Veterinary Medical Center

BACKGROUND: Pimobendan is effective in treatment of dogs with congestive heart failure (CHF) secondary to myxomatous mitral valve disease (MMVD). Its effect on dogs before the onset of CHF is unknown. HYPOTHESIS/OBJECTIVES: Administration of pimobendan (0.4-0.6 mg/kg/d in divided doses) to dogs with increased heart size secondary to preclinical MMVD, not receiving other cardiovascular medications, will delay the onset of signs of CHF, cardiac-related death, or euthanasia. ANIMALS: 360 client-owned dogs with MMVD with left atrial-to-aortic ratio ≥1.6, normalized left ventricular internal diameter in diastole ≥1.7, and vertebral heart sum >10.5. METHODS: Prospective, randomized, placebo-controlled, blinded, multicenter clinical trial. Primary outcome variable was time to a composite of the onset of CHF, cardiac-related death, or euthanasia. RESULTS: Median time to primary endpoint was 1228 days (95% CI: 856-NA) in the pimobendan group and 766 days (95% CI: 667-875) in the placebo group (P = .0038). Hazard ratio for the pimobendan group was 0.64 (95% CI: 0.47-0.87) compared with the placebo group. The benefit persisted after adjustment for other variables. Adverse events were not different between treatment groups. Dogs in the pimobendan group lived longer (median survival time was 1059 days (95% CI: 952-NA) in the pimobendan group and 902 days (95% CI: 747-1061) in the placebo group) (P = .012). CONCLUSIONS AND CLINICAL IMPORTANCE: Administration of pimobendan to dogs with MMVD and echocardiographic and radiographic evidence of cardiomegaly results in prolongation of preclinical period and is safe and well tolerated. Prolongation of preclinical period by approximately 15 months represents substantial clinical benefit.

Scrub typhus is a life-threatening zoonosis caused by Orientia tsutsugamushi organisms that are transmitted by the larvae of trombiculid mites. Endemic scrub typhus was originally thought to be confined to the so called "tsutsugamushi triangle" within the Asia-Pacific region. In 2006, however, two individual cases were detected in the Middle East and South America, which suggested that the pathogen was present farther afield. Here, we report three autochthonous cases of scrub typhus caused by O. tsutsugamushi acquired on Chiloé Island in southern Chile, which suggests the existence of an endemic focus in South America. (Funded by the Chilean Comisión Nacional de Investigación Científica y Tecnológica and the Wellcome Trust.).

In this study, atmospheric nonequilibrium plasmas were generated with six gas species using a multi-gas plasma jet.

ABSTRACT A survey was made of 284 canine and 298 feline fractures admitted to a metropolitan small animal hospital over a 2‐year period. Approximately 80% of fractures occurred in animals less than 3‐years old. Males were more commonly involved than females in both species. Road accidents were the main cause of fracture but falls and crush injuries were more common in dogs than cats. Bones most commonly affected in the cat were femur (28·2%), pelvis (24·8%) and mandible (11·4%), and in the dog radius and ulna (17·3%), pelvis (15·8%), femur (14·8), and tibia (14·8%). Forty percent of fractures were treated conservatively or by external fixation, 46·8% by internal fixation, and 13‐1% were not treated. Results were satisfactory in 96·7% of treated cases.

The use of chemical compounds benefits society in a number of ways. Pesticides, for instance, enable foodstuffs to be produced in sufficient quantities to satisfy the needs of millions of people, a condition that has led to an increase in levels of life expectancy. Yet, at times, these benefits are offset by certain disadvantages, notably the toxic side effects of the chemical compounds used. Exposure to these compounds can have varying effects, ranging from instant death to a gradual process of chemical carcinogenesis. There are three stages involved in chemical carcinogenesis. These are defined as initiation, promotion and progression. Each of these stages is characterised by morphological and biochemical modifications and result from genetic and/or epigenetic alterations. These genetic modifications include: mutations in genes that control cell proliferation, cell death and DNA repair--i.e. mutations in proto-oncogenes and tumour suppressing genes. The epigenetic factors, also considered as being non-genetic in character, can also contribute to carcinogenesis via epigenetic mechanisms which silence gene expression. The control of responses to carcinogenesis through the application of several chemical, biochemical and biological techniques facilitates the identification of those basic mechanisms involved in neoplasic development. Experimental assays with laboratory animals, epidemiological studies and quick tests enable the identification of carcinogenic compounds, the dissection of many aspects of carcinogenesis, and the establishment of effective strategies to prevent the cancer which results from exposure to chemicals.

OBJECTIVE: To determine the proportion of dogs with thoracolumbar intervertebral disk herniation (IVDH) that successfully recovered following hemilaminectomy and fenestration, the time to ambulation (TTA) in affected dogs after surgery, and the frequency of urinary and fecal incontinence in recovered dogs and to document long-term complications. DESIGN: Retrospective case series. ANIMALS: 831 dogs with thoracolumbar IVDH treated by hemilaminectomy and concomitant disk fenestration by the same surgeon. PROCEDURES: For all dogs, neurologic deficits before surgery had been assessed with a modified grading system. Dogs were reexamined after surgery over a period of 3 to 6 months, and follow-up evaluation was performed at > 12 months. The proportion of dogs that neurologically improved after surgery, TTA, and incidence of fecal or urinary incontinence in recovered dogs were compared among dogs with various grades of neurologic dysfunction before surgery. RESULTS: Of 831 dogs, 122 had unsuccessful outcomes and 709 had successful outcomes. Of 620 dogs with intact deep nociception before surgery, 606 (97.7%) were ambulatory after surgery. Despite maintaining the ability to walk, 7 dogs were judged to have an unsuccessful outcome because the severity of ataxia did not improve. Of 211 paraplegic dogs with loss of deep nociception, 110 (52.1%) dogs became ambulatory after surgery. Long-term complications included incontinence, permanent neurologic deterioration, and self-mutilation. Dogs with paraplegia before surgery had a higher frequency of urinary or fecal incontinence, compared with dogs that were ambulatory. CONCLUSIONS AND CLINICAL RELEVANCE: Prognosis for dogs with thoracolumbar IVDH that retain deep nociception in at least 1 of the pelvic limbs or tail before surgery was good.

PURPOSE: Cyclooxygenase inhibitors show promise in chemoprevention and therapy of certain carcinomas, an effect that may be additive to that of standard chemotherapy. The purpose of this study was to evaluate the efficacy of combined therapy using the cyclooxygenase inhibitor, piroxicam, and mitoxantrone against a relevant canine model of human invasive bladder cancer. EXPERIMENTAL DESIGN: Fifty-five dogs with transitional cell carcinoma of the urinary bladder were enrolled in this nonrandomized one-armed prospective multi-institutional clinical trial. Mitoxantrone was administered i.v. (5 mg/m(2)) every 21 days for four treatments, and piroxicam was administered p.o. (0.3 mg/kg/day) for the study duration. Tumor staging was performed at baseline, day 42 and every 3 months after protocol completion. Endpoints included time-to-treatment failure and survival time (ST). RESULTS: Response data were available for 48 dogs and included one complete response, 16 partial responses, 22 with disease stabilization, and 9 with progressive disease for an overall 35.4% measurable response rate. Subjective improvement occurred in 75% of treated dogs. Median time-to-treatment failure and ST were 194 and 350 days, respectively. Using censoring and end point definitions similar to those of previous reports of dogs treated with piroxicam alone, the median ST in this study was 291 days, compared with 181 days with piroxicam alone. Diarrhea and azotemia were the most common treatment complications. CONCLUSIONS: Mitoxantrone/piroxicam induced remission more frequently than previously reported for either drug as a single agent in this canine model of invasive human transitional cell carcinoma. Additional evaluation of these drugs in combination protocols should be explored.

Rats infected with the intestinal nematode Nippostrongylus brasiliensis have crypt hyperplasia with villous atrophy in affected areas of the small intestine. In thymus-deprived (B) rats the course of infection is prolonged but, despite the presence of many worms in the intestinal lumen, villi and crypts appear largely normal. This suggests that the tissue damaged associated with N. brasilliensis infection is caused, not by the worms, but by a local thymus-dependent immune reaction. There is some evidence to implicate lymphocytes rather than antibodies in this reaction. It is already know that T-cell-associated damage to the small intestine, such as occurs in allograft rejection, produces subtotal villous atrophy. The present findings suggest that when T cell react locally with helminth antigens a similar type of damage occurs. The presence of a local cell-mediated immune reaction may be the common factor which causes villous atrophy and crypt hyperplasia in many small intestinal diseases, eg, viral enteritis, giardiasis, cow's milk allergy, and coeliac disease.

As community efforts to reduce the overpopulation and euthanasia of unwanted and unowned cats and dogs have increased, many veterinarians have increasingly focused their clinical efforts on the provision of spay-neuter services. Because of the wide range of geographic and demographic needs, a wide variety of spay-neuter programs have been developed to increase delivery of services to targeted populations of animals, including stationary and mobile clinics, MASH-style operations, shelter services, community cat programs, and services provided through private practitioners. In an effort to promote consistent, high-quality care across the broad range of these programs, the Association of Shelter Veterinarians convened a task force of veterinarians to develop veterinary medical care guidelines for spay-neuter programs. These guidelines consist of recommendations for general patient care and clinical procedures, preoperative care, anesthetic management, surgical procedures, postoperative care, and operations management. They were based on current principles of anesthesiology, critical care medicine, infection control, and surgical practice, as determined from published evidence and expert opinion. They represent acceptable practices that are attainable in spay-neuter programs regardless of location, facility, or type of program. The Association of Shelter Veterinarians envisions that these guidelines will be used by the profession to maintain consistent veterinary medical care in all settings where spay-neuter services are provided and to promote these services as a means of reducing sheltering and euthanasia of cats and dogs.

OBJECTIVE: To evaluate treatment outcome in dogs with separation anxiety and owner compliance with and perception of effectiveness of discharge instructions. DESIGN: Cohort study. ANIMALS: 52 dogs with separation anxiety. PROCEDURE: Sex, age at which the owner obtained the dog, age at which separation anxiety was first noticed, age at behavioral examination, and discharge instructions were obtained from medical records of each dog. Between 6 and 64 months after the behavioral examination, owners were contacted by telephone and questioned about the outcome of treatment, their compliance with discharge instructions, and their perception of the effectiveness of each instruction. RESULTS: Thirty-two (62%) dogs had improved, whereas 20 were the same, were worse, or had been euthanatized or given away. Mixed-breed dogs were significantly less likely to improve than purebred dogs. Compliance varied according to discharge instruction. Significantly fewer dogs with owners that were given > 5 instructions improved or were cured, compared with those with owners given fewer instructions. Twenty-seven dogs were also treated with amitriptyline or other medication; 15 (56%) improved. CONCLUSIONS AND CLINICAL RELEVANCE: Owners complied with instructions that involved little time such as omitting punishment and providing a chew toy at the time of departure. Owners were also willing to increase the dog's exercise but were not willing to uncouple the cues of departure from real departures or desensitize the dog to impending departure. Administration of psychoactive medication may be necessary to augment behavior modification techniques designed to reduce separation anxiety in dogs.

A new subspecies, Staphylococcus schleiferi subsp. coagulans, was isolated from the external auditory meatus of dogs suffering from external ear otitis and is described on the basis of studies of 21 strains. Phenotypic studies showed that these strains are more closely related to Staphylococcus intermedius than to other staphylococci, but DNA hybridization studies indicated that they are closely related to Staphylococcus schleiferi N850274T. On the basis of biochemical distinctiveness (positive test tube coagulase test and different carbohydrate reactions) and the etiological importance (frequent isolation from otitis specimens from dogs) of these strains, we propose to classify them as a subspecies of S. schleiferi. The strains of this new subspecies are coagulase tube test, beta-hemolysin, and heat-stable nuclease positive but clumping factor negative. A simple scheme for the differentiation of S. schleiferi subsp. coagulans from the other coagulase-positive staphylococci is presented. The type strain is GA211 (= JCM 7470).

OBJECTIVES: We aimed to validate and determine the accuracy of a new sandwich ELISA for canine N-terminal pro-B-type natriuretic peptide (NT-proBNP) in the discrimination of canine patients with cardiac disease from those with respiratory disease and to determine the effect of confounding variables on NT-proBNP concentrations. METHODS: Validation studies for the new assay were undertaken. Concentrations of N-terminal atrial natriuretic peptide (NT-proANP) and NT-proBNP in both ethylenediaminetetraacetic acid (EDTA) plasma and serum were estimated in samples from 77 dogs at a laboratory blinded to the clinical status of the patient. The diagnostic accuracy of the each sample type and test was evaluated using receiver operating characteristic curves. The effect of age, gender and indicators of renal function was evaluated using a multivariate regression analysis. RESULTS: Concentrations of NT-proBNP in both serum and plasma accurately discriminated dogs with respiratory disease from those with cardiac disease, with an optimum cut-off concentration of 210 pmol/l. NT-proBNP concentrations were unaffected by sample type. Increasing creatinine concentration is associated with increasing concentration of NT-proBNP. Age and gender were not found to have significant effects on natriuretic peptide concentrations in this population. CLINICAL SIGNIFICANCE: Canine NT-proBNP appears to be a useful marker of the presence of cardiac disease, although concentrations must be interpreted in the light of the patient's renal function.

A total of 1235 tracheal aspirates taken from 724 thoroughbreds in race training, aged from two to 10 years, were examined cytologically and bacteriologically. An inflammation scoring system on a scale of 0 to 9 was devised to allow the severity of lower airway disease to be assessed from the cytological results. The inflammation scores were closely related to the isolation of bacteria (P<0.001), and the most common bacterial isolates were Streptococcus zooepidemicus, Streptococcus pneumoniae and Pasteurella/Actinobacillus-like species. Lower airway disease was less common in older horses (P = 0.031), and the groups at highest risk were the two- and four-year-olds. Lower airway inflammation was more common in the four-year-olds at National Hunt yards than in the four-year-olds at flat racing yards (P = 0.040, odds ratio = 3.80).

The prevalence of syringomyelia was investigated in a sample population of 555 Cavalier King Charles spaniels. All dogs, which were declared by their owners to be showing no clinical signs of syringomyelia, underwent MRI to determine the presence or absence of the condition. Data were analysed by logistic regression to determine the effects of sex and age on the prevalence of syringomyelia. Only increased age was found to have a significant effect. The prevalence of syringomyelia was 25 per cent in dogs aged 12 months, increasing to a peak of 70 per cent in dogs aged 72 months or more.

Information is provided on the productivity and economic impacts of PRRS disease in the U.S. breeding herd and growing pig herd. The total annual loss from PRRS in U.S. breeding herds was estimated at $302.06 million, i.e., $52.19 per breeding female or $2.36 per pig weaned. The majority of the loss in the breeding herd was due to reduced revenue ($300.4 million) resulting from weaning 8.3 million fewer pigs. Combining the losses in the breeding and growing pig herds resulted in 9.9 million fewer pigs, or 2.41 billion fewer pounds of pork (carcass weight), sold per year in the U.S. The estimated annual loss in the growing pig herd was $361.8 million or $62.52 per breeding female. As in the breeding herd, lost revenue of $1.62 billion, rather than increased cost, was the primary source of losses attributed to PRRS. With PRRS, costs were lowered by $1.25 billion because fewer pigs and pounds of pork were produced, thereby partially offsetting the lost revenue. In summary, the estimated total cost of PRRS in the U.S. national breeding and growing pig herd was at $664 million annually ($1.8 million per day). In addition, information on veterinary costs, biosecurity costs, and other costs from the survey of expert opinion were used to estimate these annual costs attributed to PRRS virus. The additional veterinary costs were estimated to be $140.11 million annually. The annual biosecurity and other outbreak related costs attributed to PRRS were estimated to be $191.86 million and $145.82 million, respectively. The total additional costs attributed to PRRS for veterinary, biosecurity and other outbreak related costs were $477.79 million annually.

BACKGROUND: Invasive urothelial carcinoma (iUC) is a major cause of death in humans, and approximately 165,000 individuals succumb to this cancer annually worldwide. Comparative oncology using relevant animal models is necessary to improve our understanding of progression, diagnosis, and treatment of iUC. Companion canines are a preferred animal model of iUC due to spontaneous tumor development and similarity to human disease in terms of histopathology, metastatic behavior, and treatment response. However, the comprehensive molecular characterization of canine iUC is not well documented. In this study, we performed transcriptome analysis of tissue samples from canine iUC and normal bladders using an RNA sequencing (RNA-Seq) approach to identify key molecular pathways in canine iUC. METHODS: Total RNA was extracted from bladder tissues of 11 dogs with iUC and five healthy dogs, and RNA-Seq was conducted. Ingenuity Pathway Analysis (IPA) was used to assign differentially expressed genes to known upstream regulators and functional networks. RESULTS: receptor EP2), which is consistent with the therapeutic efficiency of cyclooxygenase inhibitors in canine iUC. Similar to human iUC, canine iUC exhibited upregulated ERBB2 and downregulated TP53 pathways. Biological functions associated with cancer, cell proliferation, and leukocyte migration were predicted to be activated, while muscle functions were predicted to be inhibited, indicating muscle-invasive tumor property. CONCLUSIONS: Our data confirmed similarities in gene expression patterns between canine and human iUC and identified potential therapeutic targets (PTGER2, ERBB2, CCND1, Vegf, and EGFR), suggesting the value of naturally occurring canine iUC as a relevant animal model for human iUC.

Glycolytic glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a multifunctional protein that also mediates cell death under oxidative stress. We reported previously that the active-site cysteine (Cys-152) of GAPDH plays an essential role in oxidative stress-induced aggregation of GAPDH associated with cell death, and a C152A-GAPDH mutant rescues nitric oxide (NO)-induced cell death by interfering with the aggregation of wild type (WT)-GAPDH. However, the detailed mechanism underlying GAPDH aggregate-induced cell death remains elusive. Here we report that NO-induced GAPDH aggregation specifically causes mitochondrial dysfunction. First, we observed a correlation between NO-induced GAPDH aggregation and mitochondrial dysfunction, when GAPDH aggregation occurred at mitochondria in SH-SY5Y cells. In isolated mitochondria, aggregates of WT-GAPDH directly induced mitochondrial swelling and depolarization, whereas mixtures containing aggregates of C152A-GAPDH reduced mitochondrial dysfunction. Additionally, treatment with cyclosporin A improved WT-GAPDH aggregate-induced swelling and depolarization. In doxycycline-inducible SH-SY5Y cells, overexpression of WT-GAPDH augmented NO-induced mitochondrial dysfunction and increased mitochondrial GAPDH aggregation, whereas induced overexpression of C152A-GAPDH significantly suppressed mitochondrial impairment. Further, NO-induced cytochrome c release into the cytosol and nuclear translocation of apoptosis-inducing factor from mitochondria were both augmented in cells overexpressing WT-GAPDH but ameliorated in C152A-GAPDH-overexpressing cells. Interestingly, GAPDH aggregates induced necrotic cell death via a permeability transition pore (PTP) opening. The expression of either WT- or C152A-GAPDH did not affect other cell death pathways associated with protein aggregation, such as proteasome inhibition, gene expression induced by endoplasmic reticulum stress, or autophagy. Collectively, these results suggest that NO-induced GAPDH aggregation specifically induces mitochondrial dysfunction via PTP opening, leading to cell death. Glycolytic glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a multifunctional protein that also mediates cell death under oxidative stress. We reported previously that the active-site cysteine (Cys-152) of GAPDH plays an essential role in oxidative stress-induced aggregation of GAPDH associated with cell death, and a C152A-GAPDH mutant rescues nitric oxide (NO)-induced cell death by interfering with the aggregation of wild type (WT)-GAPDH. However, the detailed mechanism underlying GAPDH aggregate-induced cell death remains elusive. Here we report that NO-induced GAPDH aggregation specifically causes mitochondrial dysfunction. First, we observed a correlation between NO-induced GAPDH aggregation and mitochondrial dysfunction, when GAPDH aggregation occurred at mitochondria in SH-SY5Y cells. In isolated mitochondria, aggregates of WT-GAPDH directly induced mitochondrial swelling and depolarization, whereas mixtures containing aggregates of C152A-GAPDH reduced mitochondrial dysfunction. Additionally, treatment with cyclosporin A improved WT-GAPDH aggregate-induced swelling and depolarization. In doxycycline-inducible SH-SY5Y cells, overexpression of WT-GAPDH augmented NO-induced mitochondrial dysfunction and increased mitochondrial GAPDH aggregation, whereas induced overexpression of C152A-GAPDH significantly suppressed mitochondrial impairment. Further, NO-induced cytochrome c release into the cytosol and nuclear translocation of apoptosis-inducing factor from mitochondria were both augmented in cells overexpressing WT-GAPDH but ameliorated in C152A-GAPDH-overexpressing cells. Interestingly, GAPDH aggregates induced necrotic cell death via a permeability transition pore (PTP) opening. The expression of either WT- or C152A-GAPDH did not affect other cell death pathways associated with protein aggregation, such as proteasome inhibition, gene expression induced by endoplasmic reticulum stress, or autophagy. Collectively, these results suggest that NO-induced GAPDH aggregation specifically induces mitochondrial dysfunction via PTP opening, leading to cell death.

Interleukin-1β (IL-1β) is a proinflammatory cytokine that plays a central role in inflammatory bowel disease (IBD). In order to elucidate the mechanism of motility disorders frequently observed in IBD, we investigated the long term effects of IL-1β on rat ileal smooth muscle contractility by using an organ culture system. When ileal smooth muscle strips were cultured with IL-1β (10 ng/ml), contractions elicited by high K+ and carbachol were inhibited in a time-dependent manner. IL-1β more strongly inhibited the carbachol-induced contractions than high K+ with decreasing myosin light chain phosphorylation. In the α-toxin-permeabilized ileal muscle, carbachol with GTP or guanosine 5′-3-O-(thio)triphosphate increased the Ca2+ sensitivity of contractile elements, and this G protein-coupled Ca2+ sensitization was significantly reduced in the IL-1β-treated ileum. Among the functional proteins involved in the smooth muscle Ca2+ sensitization, CPI-17 expression was significantly reduced after the culture with IL-1β, whereas the expressions of RhoA, ROCK-I, ROCK-II, MYPT-1, myosin light chain kinase, and myosin phosphatase (PP1) were unchanged. The phosphorylation level of CPI-17 by carbachol was low in accordance with the decrease in CPI-17 expression due to IL-1β treatment. In contrast, constitutively phosphorylated MYPT-1 was also decreased in the IL-1β-treated muscles. These results suggest that long term treatment with IL-1β decreases either CPI-17 expression or MYPT-1 phosphorylation, which may result in an increase in myosin phosphatase activity to reduce force generation. Based on these findings, we consider IL-1β to be an important mediator of gastrointestinal motility disorders in IBD, and CPI-17 and MYPT-1 are key molecules in the decreased smooth muscle contractility due to IL-1β. Interleukin-1β (IL-1β) is a proinflammatory cytokine that plays a central role in inflammatory bowel disease (IBD). In order to elucidate the mechanism of motility disorders frequently observed in IBD, we investigated the long term effects of IL-1β on rat ileal smooth muscle contractility by using an organ culture system. When ileal smooth muscle strips were cultured with IL-1β (10 ng/ml), contractions elicited by high K+ and carbachol were inhibited in a time-dependent manner. IL-1β more strongly inhibited the carbachol-induced contractions than high K+ with decreasing myosin light chain phosphorylation. In the α-toxin-permeabilized ileal muscle, carbachol with GTP or guanosine 5′-3-O-(thio)triphosphate increased the Ca2+ sensitivity of contractile elements, and this G protein-coupled Ca2+ sensitization was significantly reduced in the IL-1β-treated ileum. Among the functional proteins involved in the smooth muscle Ca2+ sensitization, CPI-17 expression was significantly reduced after the culture with IL-1β, whereas the expressions of RhoA, ROCK-I, ROCK-II, MYPT-1, myosin light chain kinase, and myosin phosphatase (PP1) were unchanged. The phosphorylation level of CPI-17 by carbachol was low in accordance with the decrease in CPI-17 expression due to IL-1β treatment. In contrast, constitutively phosphorylated MYPT-1 was also decreased in the IL-1β-treated muscles. These results suggest that long term treatment with IL-1β decreases either CPI-17 expression or MYPT-1 phosphorylation, which may result in an increase in myosin phosphatase activity to reduce force generation. Based on these findings, we consider IL-1β to be an important mediator of gastrointestinal motility disorders in IBD, and CPI-17 and MYPT-1 are key molecules in the decreased smooth muscle contractility due to IL-1β. Interleukin-1β (IL-1β) 1The abbreviations used are: ILinterleukinIBDinflammatory bowel diseaseMLCmyosin light chainMLCKmyosin light chain kinaseGTPγSguanosine 5′-3-O-(thio)triphosphatePP1myosin phosphataseDTTdithiothreitolPBSphosphate-buffered salinePVDFpolyvinylidene difluoridePKCprotein kinase CiNOSinducible NO synthasePIPES1,4-piperazinediethanesulfonic acidDBP12-deoxyphorbol 13-isobutyratePKNprotein kinase N. is a proinflammatory cytokine that activates many immune and inflammatory cells. It is produced by various cell types, including monocytes/macrophages, neutrophils, endothelial cells, and smooth muscle cells. The biological actions of IL-1β are regulated at a transcriptional and post-transcriptional level. Expression of IL-1β is regulated by activation of mitogen-activating protein kinase and transcriptional repressors. In addition, as post-transcriptional regulation, IL-1 receptor antagonist, which is produced by the same cells as IL-1β itself, competitively counteracts the actions of IL-1β (1.Dinarello C.A. Cytokine Growth Factor Rev. 1997; 8: 253-265Crossref PubMed Scopus (615) Google Scholar). interleukin inflammatory bowel disease myosin light chain myosin light chain kinase guanosine 5′-3-O-(thio)triphosphate myosin phosphatase dithiothreitol phosphate-buffered saline polyvinylidene difluoride protein kinase C inducible NO synthase 1,4-piperazinediethanesulfonic acid 12-deoxyphorbol 13-isobutyrate protein kinase N. Motility disorders of the gastrointestinal tract are extremely important clinically because they can lead to systemic disease. Intestinal inflammation results in a disturbance of motility in human and in animal models, which may reflect an alternation in the function of smooth muscle and/or the enteric nervous system (2.Vermillion D.L. Huizinga J.D. Riddell R.H. Collins S.M. Gastroenterology. 1993; 104: 1692-1699Abstract Full Text PDF PubMed Scopus (107) Google Scholar). Elevated IL-1β levels are frequently seen in both mucosa and the muscle layer during acute and chronic intestinal inflammation, including inflammatory lesions of patients with forms of inflammatory bowel disease (IBD) such as Crohn's disease and ulcerative colitis (3.Rogler G. Andus T. World J. Surg. 1998; 22: 382-389Crossref PubMed Scopus (457) Google Scholar, 4.Vrees M.D. Pricolo V.E. Potenti F.M. Cao W. Arch. Surg. 2002; 137: 436-445Crossref Google Scholar). As for the IL-1β-producing cells in the intestinal smooth muscle layer during chronic intestinal inflammation, it is attractive to consider resident macrophages, which are regularly distributed with a network structure in the subserosa, at the level of the myenteric plexus, and inside the muscle layer (5.Mikkelsen H.B. Thuneberg L. Rumessen J.J. Thorball N. Anat. Rec. 1985; 213: 77-86Crossref PubMed Scopus (78) Google Scholar, 6.Hori M. Kita M. Torihashi S. Miyamoto S. Won K.J. Sato K. Ozaki H. Karaki H. Am. J. Physiol. 2001; 280: G930-G938Crossref PubMed Google Scholar, 7.Bauer A.J. Schwarz N.T. Moore B.A. Turler A. Kalff J.C. Curr. Opin. Crit. Care. 2002; 8: 152-157Crossref PubMed Scopus (89) Google Scholar). Regarding the short term action of IL-1β, IL-1β has been reported to inhibit smooth muscle contractility by modulating the release of acetylcholine, norepinephrine, and substance P, all of which are neuromediators located in the rat myenteric plexus. However, these inhibitory effects disappear within a few hours (8.Main C. Blennerhassett P. Collins S.M. Gastroenterology. 1993; 104: 1648-1654Abstract Full Text PDF PubMed Scopus (76) Google Scholar, 9.Hurst S. Collins S.M. Am. J. Physiol. 1993; 264: G30-G35PubMed Google Scholar, 10.Hurst S.M. Stanisz A.M. Sharkey K.A. Collins S.M. Gastroenterology. 1993; 105: 1754-1760Abstract Full Text PDF PubMed Google Scholar). In contrast, concerning the chronic effects of IL-1β on intestinal motility, few data are available in published reports. The main reason for this lack of data is the difficulty of keeping the smooth muscle phenotype in cultured cells, i.e. smooth muscle cells in culture rapidly lose their contractile phenotype (11.Chamley-Campbell J. Campbell G.R. Ross R. Physiol. Rev. 1979; 59: 1-61Crossref PubMed Scopus (1266) Google Scholar). One explanation for this loss is that the absence of extracellular matrix constituents accelerates a change of phenotype to that of proliferative smooth muscle (12.Li X. Tsai P. Wieder E.D. Kribben A. Van Putten V. Schrier R.W. Nemenoff R.A. J. Biol. Chem. 1994; 269: 19653-19658Abstract Full Text PDF PubMed Google Scholar, 13.Thyberg J. Int. Rev. Cytol. 1996; 169: 183-265Crossref PubMed Google Scholar). Therefore, because of the presence of a surrounding matrix, an organ culture system is effective for use in assessing the long term effects of IL-1β on modification of intestinal smooth muscle functions. In vascular diseases such as arteriosclerosis, it is well known that many inflammatory cytokines, including IL-1β and growth factors, affect vascular smooth muscle differentiation (14.Ross R. N. J. PubMed Scopus Google Scholar). muscle cells change a contractile to a proliferative which in to a change in the expression levels of contractile proteins such as and myosin in a in force M. M. K. K. S. M. H. M. 1993; PubMed Scopus Google Scholar, S. A. R. P. Biol. 1997; PubMed Scopus Google Scholar). These observed in vascular proliferative disease been well in using organ culture in which been with a of various growth H. Sato K. M. Ozaki H. S. H. K. Karaki H. PubMed Scopus Google Scholar). muscle contractile system is regulated by myosin light chain phosphorylation, which is by the activity and myosin phosphatase activity Rev. Physiol. PubMed Scopus Google Scholar). receptor contractile are to Ca2+ to a phosphorylation and force at a Ca2+ level M. Karaki H. 1998; PubMed Scopus Google Scholar, J. Physiol. Scopus Google Scholar, G. J. Physiol. 2001; PubMed Scopus Google Scholar). that a RhoA, and a role in Ca2+ The activates which in a of myosin phosphatase the myosin phosphatase the receptor also activates The phosphatase M. S. M. 1997; PubMed Scopus Google Scholar, S. M. M. J. PubMed Scopus Google which in myosin As a phosphorylation is to a at a In addition, it that CPI-17 phosphorylation can also be produced by or after the receptor T. M. M. J. Physiol. Scopus Google Scholar, M. M. J. T. K. K. T. PubMed Scopus Google Scholar, T. M. J. T. M. H. K. M. K. T. PubMed Scopus (78) Google Scholar). In the using an organ culture we investigated long term treatment with IL-1β can affect the contractile of ileal smooth muscle, and it the contractile that long term of IL-1β the force due to activation of G protein-coupled by myosin phosphatase activity the in CPI-17 and MYPT-1 in intestinal smooth muscles. and and treatment were in with the of the of and are with the for the and of the of were by a to the and of the was and in were the of the smooth The strips were to culture with with and and The culture were at in an of and The was smooth muscle strips were as of strips were in which and was also to The high K+ was by with These were with at and was with a of the muscle strips was to a a of for in a or was to high K+ were by the of the of the the of muscle was force is in of muscle was by the intestinal smooth muscle strips with as T. S. K. J. Biol. Chem. 264: Full Text PDF PubMed Google Scholar, J. M. C. PubMed Scopus Google Scholar). The K+ and Ca2+ were by an of The of for Ca2+ was to be force was by an a of at were by of Ca2+ strips of rat were in to to and and to and and to and and to CPI-17 and MYPT-1 and dithiothreitol and of for at at the was used for the RhoA, ROCK-II, MYPT-1, and or of proteins rat were in and of or was to was proteins were to a The was with phosphate-buffered saline and with as a for at of by J. of MYPT-1 CPI-17 and were with as the at the with for were with for protein was using phosphatase or The were as using an was as R.A. Am. J. Physiol. PubMed Google the of the during contractions by high K+ and the strips were in and The strips and were to The strips were in and of protein were on of The proteins were by and to The were for in and with of by J. of as the at the with for phosphatase was with for as were using phosphatase The were as using an MYPT-1 and CPI-17 was the of the during contractions by the strips were in and The strips and were to The strips were in and of proteins rat were in and or was to was proteins were to a The was with and with as a for at MYPT-1 and CPI-17 were with as the at the with for were with for protein was using phosphatase or The were as using an used are as GTP and are as The the and the was by of by all than were to be As a we a of the long term effects of IL-1β in rat ileal In the layer of ileal smooth muscle smooth muscle cells were in an In the layer of either or IL-1β-treated (10 for of the smooth muscle cells were also in the that the was after the culture in with or IL-1β for in the the effects of chronic treatment with IL-1β on contractility in to high K+ and carbachol in the rat ileum. The high and carbachol-induced contractions were well in the cultured in for as reported in intestinal K. P. Am. J. Physiol. 1997; PubMed Google Scholar, PubMed Scopus Google Scholar). In contrast, in the presence of IL-1β, contractions elicited by high K+ and carbachol were inhibited in a time-dependent and the of was in the carbachol-induced contractions than the high The of IL-1β that and IL-1β of contractile in ileal smooth cultured for also to IL-1β the for of carbachol to contractions in ileal smooth muscle cultured with or IL-1β for and also in was in and IL-1β-treated IL-1β, In vascular smooth IL-1β has been to expression that results in a of contractile force R. A. PubMed Scopus Google Scholar, Am. J. Physiol. 1998; Google Scholar). expression is with the expression of S. M. R. P. G. PubMed Scopus Google Scholar, M. Kita M. Torihashi S. Miyamoto S. Won K.J. Sato K. Ozaki H. Karaki H. Am. J. Physiol. 2001; 280: G930-G938Crossref PubMed Google Scholar, D.L. J. PubMed Scopus Google Scholar). Therefore, we the effects of NO synthase and also (10 on smooth muscle contractility that been by IL-1β treatment. high to the NO was to the A. Am. J. Physiol. 1996; Google Scholar). on the carbachol-induced contractions in both and with IL-1β for In addition, change the carbachol-induced contractions in with or IL-1β. (10 affect the carbachol-induced contractions of smooth muscle cultured with or IL-1β These results are in treatment with both and the reduced high contractions elicited by IL-1β treatment of the of NO NO synthase and (10 on carbachol contractions in rat ileal smooth muscle cultured with or IL-1β (10 for (10 in a the phosphorylation of which the contractions of smooth As in the levels of phosphorylation in IL-1β-treated strips in the the When contractions were in to treatment with carbachol for the phosphorylation levels significantly In the IL-1β-treated the levels of phosphorylation by carbachol were significantly than in the IL-1β, of the with high K+ for also increased phosphorylation, and this was significantly reduced by the IL-1β treatment IL-1β, in α-toxin-permeabilized muscle, functional proteins in are and Ca2+ can be in order to Ca2+ sensitivity and the contractility of the contractile T. S. K. J. Biol. Chem. 264: Full Text PDF PubMed Google Scholar, J. M. C. PubMed Scopus Google Scholar). In the muscle the of Ca2+ As in in Ca2+ of the contractions by of the muscle with carbachol in the presence of GTP increased the contractions elicited by The Ca2+ sensitization by carbachol with GTP in the presence of Ca2+ was significantly reduced by the IL-1β treatment IL-1β, of carbachol with the of also significantly increased the Ca2+ sensitivity of the contractile and the level of contractile force was significantly decreased by IL-1β treatment IL-1β, the effects of an of on contractions in the muscle with In both and IL-1β-treated the contractile force by Ca2+ was significantly increased by However, the of of the contractile force was than that of the In addition, the force by Ca2+ with was significantly decreased by the IL-1β treatment. the contractile force by Ca2+ The force by Ca2+ was significantly decreased by the IL-1β treatment IL-1β, in Expression of the protein expression of and the of the the expression of in the cultured after the culture in When muscle was with IL-1β in the expression of was significantly the In addition, the expression of IL-1β, IL-1β, and IL-1β, change after the IL-1β treatment these results suggest the that IL-1β treatment the mechanism for the G protein-coupled Ca2+ sensitization of the contractile Therefore, we the expression levels of proteins involved in the Ca2+ sensitization of smooth the in the the expression of change after the culture in When muscle was with IL-1β in for the expression change The expressions of and also and IL-1β-treated and As in the expression of MYPT-1 in IL-1β-treated that in However, CPI-17 protein expression in was significantly reduced in the with IL-1β for MYPT-1 of smooth muscle, the activates which in MYPT-1 to myosin phosphatase Therefore, we the MYPT-1 phosphorylation in carbachol-induced contractions in rat ileum. time-dependent phosphorylation of MYPT-1 at in rat with carbachol MYPT-1 was in the using MYPT-1 MYPT-1 was phosphorylated the and the level of phosphorylation of MYPT-1 significantly change within after with after the the MYPT-1 phosphorylation was significantly the effects of kinase (10 and and on the phosphorylation of MYPT-1 with carbachol for MYPT-1 phosphorylation in the presence of carbachol was inhibited by to the of which was significantly than the and also inhibited the carbachol-induced phosphorylation of MYPT-1 to and In the we also the effects of and (10 on MYPT-1 phosphorylation in the MYPT-1 phosphorylation be using this MYPT-1 CPI-17 an to Ca2+ sensitization by consider the CPI-17 phosphorylation which is by also by and which to an of myosin phosphatase activity In the in to the MYPT-1 phosphorylation, phosphorylated CPI-17 at was in the of the with carbachol increased the levels of CPI-17 phosphorylation at within with these levels for the effects of and (10 on the phosphorylation of CPI-17 by inhibited the carbachol-induced phosphorylation of CPI-17 in the to that this can the phosphorylated of inhibited the carbachol-induced CPI-17 phosphorylation carbachol with more inhibited the phosphorylation to In addition, also significantly inhibited the phosphorylation of CPI-17 to The of IL-1β on of MYPT-1 and the effects of IL-1β treatment on the MYPT-1 phosphorylation in cultured in for with or IL-1β. In the cultured for treatment with carbachol for change the phosphorylated MYPT-1 In the IL-1β-treated the MYPT-1 phosphorylated at the was significantly than that in also the CPI-17 phosphorylation in the cultured in for CPI-17 was phosphorylated in the cultured of carbachol increased the phosphorylation level at In accordance with the decrease in the of the of the phosphorylated of CPI-17 in the muscle with carbachol for was significantly in IL-1β-treated than in In the we the chronic effects of IL-1β on ileal smooth muscle contractility in an organ culture and we that treatment with IL-1β for smooth muscle important of this was that IL-1β more strongly carbachol-induced contractions than contractions by with high It has been that inducible NO synthase is in intestinal or vascular smooth muscle to IL-1β or R. A. PubMed Scopus Google Scholar, Am. J. Physiol. 1998; Google Scholar). In rat ileal smooth muscle, IL-1β has been to in activity and the decreases in muscle contractility A. Am. J. Physiol. Google Scholar). Therefore, we NO ileal is involved in the decrease in However, the of contractions was by of the with an of and/or a of the NO It has also been reported that and IL-1β expression in macrophages, in an increase in the release of to muscle M. Kita M. Torihashi S. Miyamoto S. Won K.J. Sato K. Ozaki H. Karaki H. Am. J. Physiol. 2001; 280: G930-G938Crossref PubMed Google Scholar, M. K. J. 1998; Google Scholar, S. Ozaki H. M. Kita M. S. Karaki H. Biol. PubMed Scopus Google Scholar). However, a the decrease in These results suggest the that the of muscle force may be by a change in the muscle contractility is regulated by phosphorylation the system Rev. Physiol. PubMed Scopus Google Scholar). Therefore, we the effects of IL-1β on the levels of phosphorylation by carbachol and high the levels of phosphorylation were in and IL-1β-treated the phosphorylation by carbachol at was significantly in the muscle with IL-1β for than in the muscle In with the data that high contractions are inhibited by IL-1β treatment the inhibitory effects of IL-1β on high phosphorylation were to be These results suggest that IL-1β may smooth muscle contractions at the level of the of phosphorylation for the Ca2+ sensitization of contractile As in the it is that receptor Ca2+ sensitization is by at i.e. the and the M. Sato K. Miyamoto S. Ozaki H. Karaki H. J. 1993; PubMed Scopus Google Scholar, H. Ozaki H. M. M. K. K. Miyamoto S. H. Won K.J. Sato K. Rev. 1997; Google Scholar, K. R. J. Physiol. 1994; Scopus Google Scholar, M. S. M. T. J. Physiol. 1994; 104: PubMed Scopus Google Scholar, K. A. T. S. K. H. K. J. Biol. Chem. Full Text PDF PubMed Google Scholar). In intestinal smooth it has been reported that carbachol GTP or force at Ca2+ sensitization A. K. G. J. Physiol. 1996; Scopus Google Scholar, K. K. M. P. J. Physiol. Scopus Google Scholar). an of also Ca2+ sensitization in the T. K. S. N. J. PubMed Scopus Google Scholar, J. 1996; PubMed Scopus Google Scholar). In the in rat with we that carbachol with GTP or results in Ca2+ sensitization of contractile was also to Ca2+ sensitization in the the of Ca2+ sensitization was than that by carbachol GTP or with the results results that the Ca2+ sensitization by carbachol with GTP or is significantly reduced by IL-1β treatment. In contrast, IL-1β significantly inhibited Ca2+ sensitization These results that long term treatment with IL-1β may affect the than the activates which to the phosphorylation of MYPT-1, a of myosin phosphatase J. Physiol. Scopus Google Scholar, G. J. Physiol. 2001; PubMed Scopus Google Scholar, M. T. H. T. T. T. H. K. J. M. S. 1997; PubMed Scopus Google Scholar, M. K. 2001; 22: Full Text Full Text PDF PubMed Scopus Google Scholar). The phosphorylated MYPT-1 the of myosin phosphatase in Ca2+ MYPT-1 at and phosphorylation at is to be for the of myosin phosphatase activity J. M. K. N. M. T. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). The results that MYPT-1 at is phosphorylated to level in the However, the with carbachol change MYPT-1 phosphorylation in during which the contractile a of the for with carbachol significantly increased MYPT-1 phosphorylation, was than These results with of the in the and T. M. M. J. Physiol. Scopus Google and the N. M. J. PubMed Scopus Google Scholar). Therefore, we that MYPT-1 phosphorylation an role in the Ca2+ sensitization by receptor in rat ileum. we a the of MYPT-1 phosphorylation and contractions in the we that the levels of MYPT-1 phosphorylation were significantly reduced by IL-1β the also the It is that decreased levels of the constitutively phosphorylated MYPT-1 change the which may result in a of phosphorylation with the It has been reported that MYPT-1 phosphorylation is regulated by than including A. S. A. 2001; PubMed Scopus Google A. J. 2002; PubMed Google Scholar, A. C. P. M. J. 2002; PubMed Scopus Google and A. R. K. M. 2001; PubMed Scopus Google Scholar). T. M. M. J. Physiol. Scopus Google reported that MYPT-1 phosphorylation in the is inhibited by the in the presence of phosphorylation of However, in the ileal smooth muscle, and and kinase inhibited the MYPT-1 phosphorylation in the that MYPT-1 is phosphorylated by the in the smooth muscle of rat ileum. is to the of MYPT-1 phosphorylation in rat and this may the of the mechanism in the decreased contractions in to IL-1β. the CPI-17 at which activity to Ca2+ sensitization M. S. M. 1997; PubMed Scopus Google Scholar, S. M. M. J. PubMed Scopus Google Scholar, L. M. M. T. J. Physiol. 1998; Scopus Google Scholar, T. M. D.L. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). However, on in M. M. J. T. K. K. T. PubMed Scopus Google reported that CPI-17 is a for In addition, T. M. M. J. Physiol. Scopus Google reported that CPI-17 phosphorylation is by a It has also been reported that can CPI-17 in T. M. J. T. M. H. K. M. K. T. PubMed Scopus (78) Google Scholar). These results suggest the that the and/or may also be involved in carbachol-induced contractions in rat ileum. In the in the rat CPI-17 was phosphorylated in the the of carbachol phosphorylated CPI-17 at and the phosphorylation levels were well for during the carbachol These results are with results T. M. M. J. Physiol. Scopus Google Scholar, N. M. J. PubMed Scopus Google in smooth and suggest that CPI-17 phosphorylation may a role in the carbachol-induced Ca2+ sensitization in rat ileum. in the ileal smooth muscle, inhibited the carbachol-induced increase in CPI-17 phosphorylation by inhibited the phosphorylation more than that also may be by activation may also be involved in the phosphorylation of rat because was to significantly inhibit the phosphorylation of CPI-17 The important of this is that CPI-17 expression was decreased by in ileal with IL-1β to Ca2+ sensitization of contractile proteins such as RhoA, MYPT-1, and In accordance with the decrease in CPI-17 the phosphorylated CPI-17 after carbachol was These results strongly suggest that of CPI-17 expression plays a role in the decreased Ca2+ after long term treatment with IL-1β. As in the chronic effects of IL-1β reduced high the inhibitory was than that in carbachol-induced the effects of IL-1β on high we the effects on contractions in the In the muscle with the IL-1β treatment significantly inhibited the contractile force by in the α-toxin-permeabilized muscle are to be by the increased activity of phosphatase this As because MYPT-1 activity in the was decreased after the IL-1β constitutively MYPT-1 activity may to the system in the α-toxin-permeabilized as an It is that the decrease in the force observed in the muscle may at in be by the decreased activity of the MYPT-1 It has been reported M. H. S. M. J. 2002; PubMed Scopus Google Scholar, K. M. M. T. K. Ozaki H. Karaki H. J. PubMed Scopus Google that the also the is for the high In addition, and S. N. N. M. PubMed Scopus Google reported the presence of activation of in high In the rat was to significantly inhibit high contractions in ileal by These suggest the that IL-1β an of high contractions by the In the we the chronic effects of IL-1β on gastrointestinal motility, as in an organ culture system. IL-1β expression is significantly increased in both mucosa and the muscle layer during intestinal inflammation in such as Crohn's disease and ulcerative colitis (3.Rogler G. Andus T. World J. Surg. 1998; 22: 382-389Crossref PubMed Scopus (457) Google Scholar, 4.Vrees M.D. Pricolo V.E. Potenti F.M. Cao W. Arch. Surg. 2002; 137: 436-445Crossref Google Scholar). In these motility disorders of the gastrointestinal tract are frequently and is to be extremely important as it can lead to systemic disease. In the we that long term to IL-1β a inhibitory action in intestinal muscle many such as the role of the IL-1β-producing cell in the muscle to the and the presence of with inflammatory that the decrease in muscle was in to treatment with an M. K. H. and H. and we are the of in In the results for the that long term treatment with IL-1β contractions in rat ileal smooth is by a of phosphorylation that is to the decreased activity of the proteins of myosin phosphatase such as CPI-17 and These increase of the motility disorders of the gastrointestinal tract in are to J. T. and K. of for the of

In the study presented here, we aimed to describe the epidemiological, clinical and pathological findings of 51 canine cases with histologically-verified diagnoses of primary cardiac hemangiosarcoma (HSA). The medical data for each dog, including signalment, presenting complaints, physical examination findings, results of various diagnostic testing performed and method of treatment, were checked. In addition, all 51 cases were re-examined pathologically. The tumor occurred most frequently in older Golden Retrievers, followed by Maltese dogs and Miniature Dachshunds. Mass lesions of HSA were found more commonly in the right auricle (RAu) (25/51) and right atrium (RA) (21/51), and the RA masses were significantly (P<0.001) larger than the RAu masses. The echocardiographic detection rate of masses in the RAu group (60%; 15/25) was significantly lower than that in the RA group (95%; 20/21). Survival time was significantly (P<0.05) longer for 5 dogs that received adjuvant chemotherapy after tumor resection than for 12 dogs that did not. In this series, the Maltese (9/51) and Miniature Dachshund (7/51), as well as the Golden Retriever, were represented more frequently than other breeds. The lower echocardiographic detection rate of RAu masses compared with RA masses may be related to tumor size and/or location. The significantly longer survival time for dogs receiving adjuvant chemotherapy indicates that postoperative chemotherapy could be useful for dogs with cardiac HSA.

BACKGROUND: The safety of chronically administered intrathecal morphine has been questioned. Therefore, the authors examined the behavioral and neurologic effects and neurotoxicity of continuous intrathecal morphine administration in sheep. METHODS: Groups of three sheep were implanted with intrathecal infusion systems for the continuous administration of morphine (3, 6, 9, 12, or 18 mg/day) or saline at a fixed infusion rate of 1.92 ml/day beginning approximately 7 days after implantation. Sheep were examined daily for any changes in behavior or neurologic function. After 28-30 days, the animals were humanely killed. Cerebrospinal fluid samples were collected and analyzed for protein, erythrocytes and leukocytes, and morphine content. The spinal cord and meninges with the catheter in situ was removed en bloc and fixed in formalin for histologic analysis. RESULTS: Unilateral hind-leg gait deficits were observed in two of three animals in each of the 12- and 18-mg/day dose groups. Gross and microscopic evaluation of spinal cord tissue from these animals revealed intradural-extramedullary inflammatory masses that compressed the spinal cord at the catheter-tip and mid-catheter areas. This inflammation was ipsilateral to extremities that exhibited gait deficits and had acute and chronic cellular components. CONCLUSIONS: The toxicity of intrathecal morphine seems to be dependent on the amount of morphine infused, although the effects of dose versus concentration cannot be clearly distinguished in this study. Intrathecal morphine doses of 12- 18 mg/day produced inflammatory masses extending from the catheter tip down the length of the catheter within the subarachnoid space. Doses of 6-9 mg/day produced mild-to-moderate inflammation 5 cm cranial to the catheter tip. A dose of 3 mg/day produced no neurotoxicity and spinal histopathologic changes that were equivalent to those observed in the saline-treated animals.