John Sealy Hospital

BACKGROUND: The use of androgen-deprivation therapy for prostate cancer has increased substantially over the past 15 years. This treatment is associated with a loss of bone-mineral density, but the risk of fracture after androgen-deprivation therapy has not been well studied. METHODS: We studied the records of 50,613 men who were listed in the linked database of the Surveillance, Epidemiology, and End Results program and Medicare as having received a diagnosis of prostate cancer in the period from 1992 through 1997. The primary outcomes were the occurrence of any fracture and the occurrence of a fracture resulting in hospitalization. Cox proportional-hazards analyses were adjusted for characteristics of the patients and the cancer, other cancer treatment received, and the occurrence of a fracture or the diagnosis of osteoporosis during the 12 months preceding the diagnosis of cancer. RESULTS: Of men surviving at least five years after diagnosis, 19.4 percent of those who received androgen-deprivation therapy had a fracture, as compared with 12.6 percent of those not receiving androgen-deprivation therapy (P<0.001). In the Cox proportional-hazards analyses, adjusted for characteristics of the patient and the tumor, there was a statistically significant relation between the number of doses of gonadotropin-releasing hormone received during the 12 months after diagnosis and the subsequent risk of fracture. CONCLUSIONS: Androgen-deprivation therapy for prostate cancer increases the risk of fracture.

The inducible cyclooxygenase, COX-2, has been associated with vascular inflammation and cellular proliferation. We have discovered that hypoxia increases expression of the COX-2 gene in human vascular endothelial cells in culture independent of other stimuli. Western analysis of human umbilical vein endothelial cells (HUVEC) revealed a greater than 4-fold induction of protein by hypoxia (1% O2). The steady-state level of COX-2 mRNA was correspondingly elevated by both Northern blot and reverse transcriptase-polymerase chain reaction analysis. Using electrophoretic mobility shift assays with antibody supershifting, we also found that hypoxia causes increased binding of NF-kappaB p65 (Rel A) to the one out of the two NF-kappaB consensus elements in the COX-2 promoter which is closest to the transcription start site of the COX-2 gene. Transfection of an immortalized human microvascular endothelial cell line (HMEC-1) with mutation reporter gene constructs and HUVEC with both mutation and deletion reporter gene constructs suggested that transcription of the COX-2 gene was enhanced by hypoxia. In transcription factor decoy experiments, hypoxic HUVEC were exposed in culture to 20 microM of the same NF-kappaB element found to bind NF-kappaB protein. The wild type transcription factor decoy prevented hypoxic induction of COX-2, presumably by binding with cytoplasmic p65; however, mutated or scrambled oligonucleotides did not prevent the increase in COX-2 protein expression by hypoxia. Thus, the intracellular signaling mechanism that leads to induction of COX-2 by hypoxia includes binding of p65 to the relatively 3' NF-kappaB consensus element in the COX-2 upstream promoter region in human vascular endothelial cells.

Nearly forty years ago Curran & MacIntosh (1962) presented experimental evidence for a model of water transport that would satisfy a question posed by such famous physiologists as Heidenhain and Reed before the turn of the century: how can the intestine accomplish transport of water from one isotonic compartment (the bowel lumen) to another (the blood)? Curran, who was a superb experimentalist as well as a theoretician, had previously shown that water transport bore a linear relationship to solute (Na+) transport. He and MacIntosh then demonstrated that a three-compartment model (see Fig. 1) would allow movement of fluid from compartment I to III as long as compartment II contained a solution hypertonic to I and III, and as long as the permeabilities (reflection coefficients) of the membranes A and B, which separated the compartments, were finite with B greater than A. They used cellophane for membrane A and sintered glass for membrane B in their model. The biological counterparts to these membranes were thought to be the tight junctions (TJ) of the epithelial cells for membrane A, the basement membrane (BM) for membrane B and the intercellular space (ICS) for compartment II. Active Na+ transport along the basolateral membrane of the epithelial cell into the ICS was proposed as the active solute's transport step driving the passive flow of water from I to III. Diamond's ‘standing gradient’ hypothesis of water movement was a later variation of this model (Diamond, 1978). Thus, the mystery of the special driving force, or ‘treibkraft’ moving water across the intestinal wall was solved: it was ‘compartmentalized’ osmotic pressure. Curran and MacIntosh's model system for water transport (right) is shown with proposed biological counterparts in the colonic mucosa (left). SMS, subepithelial myofibroblastic syncytium with reticular fibrils. These models of water transport were adequate to explain isotonic transport, i.e. an absorbant osmolality that was essentially isotonic with the luminal fluid and with the plasma. It was subsequently shown that the distal colon could transport fluid hypertonically, i.e. an absorbate with osmolalities of 500–1000 mosmol (kg H2O)−1. Furthermore, such hypertonic transport was necessary to dehydrate the faecal mass in the distal colon. Naftalin and colleagues have proposed that the development of hypertonic water transport allows the distal colonic crypts to act as suction devices capable of dehydrating faeces (Naftalin et al. 1999). Given known hydraulic permeabilities of the epithelial cell membranes and rates of Na+ transport, it has been difficult to imagine how the distal colon could create an osmotic gradient in the ICS sufficient to accomplish the formation of hard faeces. The two papers by Naftalin and colleagues (Naftalin et al. 1999; Naftalin & Pedley, 1999) in this issue of TheThe Journal of Physiology shed light on this question by proposing a role for the myofibroblast-reticular sheath (which they call the fibronexus). This ‘sheath’ forms a second fenestrated ‘membrane’ just under the fenestrated BM in the intestine and probably most epithelial tissues (Toyoda et al. 1997). Heretofore, this myofibroblastic syncytium had been thought only to influence intestinal secretion through prostaglandin (cyclic AMP)-mediated sensitization of intestinal epithelial cells to Ca2+-mediated secretogogues (Berschneider & Powell, 1992). Using confocal microscopy to identify this ‘sheath’ and a fluorescent probe for Na+, these investigators show that it presents a diffusion barrier to Na+ that correlates well with the gut segments that are able to transport hypertonically. These experiments suggest that the reflection coefficient of the BM is such that this barrier is adequate for isotonic transport, but that the myofibroblast-reticular sheath serves as an additional diffusion barrier in series with the BM in order to accomplish hypertonic transport. Alternatively, it may be that it is the myofibroblast-reticular sheath, and not the BM, which represents the basolateral diffusion barrier for either isotonic or hypertonic transport. The investigators have also shown a correlation between the barrier function of this sheath and a high renin-angiotensin II-aldosterone state brought about by dietary Na+ depletion. It has been previously known that such a state greatly increases distal colonic Na+ transport by increasing the resistance of the tight junctions and by increasing expression of amiloride-sensitive Na+ channels and Na+,K+-ATPase on the apical and basolateral membranes of the distal colonocyte. Naftalin and colleagues propose that this sodium depletion state also leads to greater osmotic transport, through angiotensin II- or aldosterone-induced activation of the myofibroblasts with increased synthesis and secretion of reticulin fibrils, resulting in changes in the reflection coefficient of this myofibroblast-reticular membrane. These investigators give increased verification and clearer biological counterparts to a model of transport proposed nearly half a century ago. It remains to be determined if this myofibroblast-reticular sheath has such a transport function in all electrolyte and water transporting epithelia. It appears that the syncytium of myofibroblasts exists under the epithelial BM in all transporting epithelia where it has contractile functions and growth, differentiation and wound repair functions. This syncytium will be the subject of considerable investigation over the next few years.

Physiological studies of the type we have described, when performed in patients with the WPW syndrome, can yield diagnostic information regarding the mechanism of arrhythmia, demonstrate functional properties of therapeutic import, facilitate therapeutic decision-making about drug regimens and presumptively localize the site of pre-excitation as a basis for possible surgical intervention. Based on our experience, we feel that in selected patients, surgical correction of the WPW syndrome is entirely feasible, and can be accomplished in the majority of patients in whom free wall A-V connections are present. The continuing challenge of identification and correction of septal accessory pathways directs our present work with the WPW syndrome.

Interleukin-6 (IL-6) is a multifunctional cytokine expressed by angiotensin II (Ang II)-stimulated vascular smooth muscle cells (VSMCs) that functions as an autocrine growth factor. In this study, we analyze the mechanism for Ang II-inducible IL-6 expression in quiescent rat VSMCs. Stimulation with the Ang II agonist Sar1 Ang II (100 nmol/L) induced transcriptional expression of IL-6 mRNA transcripts of 1.8 and 2.4 kb. In transient transfection assays of IL-6 promoter/luciferase reporter plasmids, Sar1 Ang II treatment induced IL-6 transcription in a manner completely dependent on the nuclear factor-kappaB (NF-kappaB) motif. Sar1 Ang II induced cytoplasmic-to-nuclear translocation of the NF-kappaB subunits Rel A and NF-kappaB1 with parallel changes in DNA-binding activity in a biphasic manner, which produced an early peak at 15 minutes followed by a nadir 1 to 6 hours later and a later peak at 24 hours. The early phase of NF-kappaB translocation was dependent on weak simultaneous proteolysis of the IkappaBalpha and beta inhibitors, whereas later translocation was associated with enhanced processing of the p105 precursor into the mature 50-kDa NF-kappaB1 form. Pretreatment with a potent inhibitor of IkappaBalpha proteolysis, TPCK, completely blocked Sar1 Ang IIAng II-induced NF-kappaB activation and induction of endogenous IL-6 gene expression, which indicated the essential role of NF-kappaB in mediating IL-6 expression. We conclude that Ang II is a pleiotropic regulator of the NF-kappaB transcription factor family and may be responsible for activating the expression of cytokine gene networks in VSMCs.

The Mexican Health and Aging Study (MHAS) was designed to prospectively evaluate the impact of disease on the health, function and mortality of adults over the age of 50 in both urban and rural areas of Mexico. The overall goal of the study is to examine the ageing process and its disease and disability burden in a large representative panel of older Mexicans, using a wide socioeconomic perspective. The study protocols and survey instruments are highly comparable to the U.S. Health and Retirement Study (HRS).The MHAS 2001 baseline is a nationally and urban-rural representative survey of individuals born in 1951 or earlier. Three waves of data have been collected so far: baseline in 2001 and follow-ups in 2003 and 2012. In 2012, the study added a representative sample of the population from the 1952-62 birth cohorts. A fourth wave will be collected in 2015.The data files and documentation are available free of charge at the study website [www.MHASweb.org] in English and [www.ENASEM.org] in Spanish.

Two candidate human orthologs of Escherichia coli MutM/Nei were recently identified in the human genome database, and one of these, NEH1, was characterized earlier (Hazra, T. K., Izumi, T., Boldogh, I., Imhoff, B., Kow, Y. W., Jaruga, P., and Dizdaroglu, M. (2002) Proc. Natl. Acad. Sci. U. S. A. 99, 3523-3528). Here we report characterization of the second protein, originally named NEH2 and now renamed NEIL2 (Nei-like). The 37-kDa wild-type NEIL2 expressed in and purified from E. coli has DNA glycosylase/AP lyase activity, primarily for excising oxidative products of cytosine, with highest activity for 5-hydroxyuracil, one of the most abundant and mutagenic lesions induced by reactive oxygen species, and with lower activity for 5,6-dihydrouracil and 5-hydroxycytosine. It has negligible or undetectable activity with 8-oxoguanine, thymine glycol, 2-hydroxyadenine, hypoxanthine, and xanthine. NEIL2 is similar to NEIL1 in having N-terminal Pro as the active site. However, unlike NEIL1, its expression was independent of the cell cycle stage in fibroblasts, and its highest expression was observed in the testes and skeletal muscle. Despite the absence of a putative nuclear localization signal, NEIL2 was predominantly localized in the nucleus. These results suggest that NEIL2 is involved in global genome repair mainly for removing oxidative products of cytosine.

We have previously shown that the natriuretic effect of rat atrial extract (AE) may be due, perhaps entirely, to its powerful renal hemodynamic actions. The present study was undertaken to test the hypothesis that mammalian atria contain a substance that behaves as a functional antagonist of endogenous vasoconstrictors, by examining the direct effects of AE and extensively purified atrial "natriuretic" factor on the contractile response of rabbit aortic rings to angiotensin II (AII), norepinephrine (NE), and K+-induced depolarization. Dose-response curves to AII and NE (i.e., change in tension vs log hormone concentration) were determined in the absence or presence of boiled AE or ventricular extracts (VE). Increasing concentrations of boiled AE caused a progressive right-ward shift of the AII and NE dose-response curves, whereas VE was without effect. A similar inhibitory effect was produced after extensive purification of atrial natriuretic factor by gel filtration and reversed-phase high performance liquid chromatography (HPLC). It appeared that this factor antagonized AII-induced contractility to a greater degree than that of NE. Moreover, the partially purified factor also inhibited the contraction induced by depolarization with 15 mM KCl in a concentration-dependent manner. These studies show that a substance present in the atria, but not ventricles, blocks both hormone- (receptor) and depolarization- (nonreceptor) induced vasoconstriction in aortic rings. Moreover, this antagonism is retained following extensive purification of an atrial factor that induces natriuresis in the intact rat and isolated rat kidney, suggesting that both the vasoactive and natriuretic properties of AE may reside in a single substance.(ABSTRACT TRUNCATED AT 250 WORDS)

OBJECTIVES: To examine the association between handgrip strength and mortality in older Mexican American men and women. DESIGN: A 5-year prospective cohort study. SETTING: Five southwestern states: Texas, New Mexico, Colorado, Arizona, and California. PARTICIPANTS: A population-based sample of 2,488 noninstitutionalized Mexican-American men and women aged 65 and older. MEASUREMENTS: Maximal handgrip strength, timed walk, and body mass index were assessed at baseline during 1993/94. Self-reports of functional disability, various medical conditions, and status at follow-up were obtained. RESULTS: Of the baseline sample with complete data, 507 persons were confirmed deceased 5 years later. Average handgrip strength +/- standard deviation was significantly higher in men (28.4 kg +/- 9.5) than in women (18.2g +/- 6.5). Of men who had a handgrip strength less than 22.01 kg and women who had a handgrip strength less than 14 kg, 38.2% and 41.5%, respectively, were dead 5 years later. In men in the lowest handgrip strength quartile, the hazard ratio of death was 2.10 (95% confidence interval (CI) = 1.31-3.38) compared with those in the highest handgrip strength quartile, after controlling for sociodemographic variables, functional disability, timed walk, medical conditions, body mass index, and smoking status at baseline. In women in the lowest handgrip strength quartile, the hazard ratio of death was 1.76 (95%I = 1.05-2.93) compared with those in the highest handgrip strength quartile. Poorer performance in the timed walk and the presence of diabetes mellitus, hypertension, and cancer were also significant predictors of mortality 5 years later. CONCLUSION: Handgrip strength is a strong predictor of mortality in older Mexican Americans, after controlling for relevant risk factors.

A liquid state theory based on site–site integral equations is constructed to have the asymptotics given by angular expansion theory. This results in a theory which shows dielectric consistency, e.g., the dielectric constant as viewed from the solvent is the same as that viewed by the ions. Such consistency is lacking in other extended reference interaction site model (XRISM)-based theories and leads to unrealistic structural predictions. The Kirkwood–Buff route to thermodynamics is used and allows a physical partitioning of the terms responsible for the solvation process. Sample results for a 1–1 salt are given.

BACKGROUND: Readmissions in patients with chronic obstructive pulmonary disease (COPD) are common and costly. We examined the effect of early follow-up visit with patient's primary care physician (PCP) or pulmonologist following acute hospitalization on the 30-day risk of an emergency department (ER) visit and readmission. METHODS: We conducted a retrospective cohort study of fee-for-service Medicare beneficiaries with an identifiable PCP who were hospitalized for COPD between 1996 and 2006. Three or more visits to a PCP in the year prior to the hospitalization established a PCP for a patient. We performed a Cox proportional hazard regression with time-dependent covariates to determine the risk of 30-day ER visit and readmission in patients with or without a follow-up visit to their PCP or pulmonologist. RESULTS: Of the 62 746 patients admitted for COPD, 66.9% had a follow-up visit with their PCP or pulmonologist within 30 days of discharge. Factors associated with lower likelihood of outpatient follow-up visit were longer length of hospital stay, prior hospitalization for COPD, older age, black race, lower socioeconomic status, and emergency admission. Those receiving care at nonteaching, for-profit, and smaller-sized hospitals were more likely to have a follow-up visit. In a multivariate, time-dependent analysis, patients who had a follow-up visit had a significantly reduced risk of an ER visit (hazard ratio [HR], 0.86; 95% confidence interval [CI], 0.83-0.90) and readmission (HR, 0.91; 95% CI, 0.87-0.96). CONCLUSION: Continuity with patient's PCP or pulmonologist after an acute hospitalization may lower rates of ER visits and readmission in patients with COPD.

BACKGROUND: National and population-based information on the increase in patient care by hospitalists in the United States is lacking. METHODS: Using a 5% sample of Medicare beneficiaries in 1995, 1997, 1999, and the period from 2001 through 2006, we identified 120,226 physicians in general internal medicine who were providing care to older patients in 5800 U.S. hospitals. We defined hospitalists as general internists who derived 90% or more of their Medicare claims for evaluation-and-management services from the care of hospitalized patients. We then calculated the percentage of all inpatient Medicare services provided by hospitalists and identified patient and hospital characteristics associated with the receipt of hospitalist services. RESULTS: The percentage of physicians in general internal medicine who were identified as hospitalists increased from 5.9% in 1995 to 19.0% in 2006, and the percentage of all claims for inpatient evaluation-and-management services by general internists that were attributed to hospitalists increased from 9.1% to 37.1% during this same period. Accompanying the increase in care by hospitalists was an increase in the percentage of all hospitalized Medicare patients who were treated by general internists (both hospitalists and traditional, non-hospital-based general internists), from 46.4% in 1995 to 61.0% in 2006. In a multilevel, multivariable analysis controlling for patient and hospital characteristics, the odds of receiving care from a hospitalist increased by 29.2% per year from 1997 through 2006. In 2006, there was marked geographic variation in the rates of care provided by hospitalists, with rates of more than 70% in some hospital-referral regions. CONCLUSIONS: These analyses of data from Medicare claims showed a substantial increase in the care of hospitalized patients by hospitalist physicians from 1995 to 2006.

Skeletal muscle atrophy during bed rest is attributed, at least in part, to slower basal muscle protein synthesis (MPS). Essential amino acids (EAA) stimulate mammalian target of rapamycin (mTORC1) signaling, amino acid transporter expression, and MPS and are necessary for muscle mass maintenance, but there are no data on the effect of inactivity on this anabolic mechanism. We hypothesized that bed rest decreases muscle mass in older adults by blunting the EAA stimulation of MPS through reduced mTORC1 signaling and amino acid transporter expression in older adults. Six healthy older adults (67 ± 2 yr) participated in a 7-day bed rest study. We used stable isotope tracers, Western blotting, and real-time qPCR to determine the effect of bed rest on MPS, muscle mTORC1 signaling, and amino acid transporter expression and content in the postabsorptive state and after acute EAA ingestion. Bed rest decreased leg lean mass by ∼4% (P < 0.05) and increased postabsorptive mTOR protein (P < 0.05) levels while postabsorptive MPS was unchanged (P > 0.05). Before bed rest acute EAA ingestion increased MPS, mTOR (Ser(2448)), S6 kinase 1 (Thr(389), Thr(421)/Ser(424)), and ribosomal protein S6 (Ser(240/244)) phosphorylation, activating transcription factor 4, L-type amino acid transporter 1 and sodium-coupled amino acid transporter 2 protein content (P < 0.05). However, bed rest blunted the EAA-induced increase in MPS, mTORC1 signaling, and amino acid transporter protein content. We conclude that bed rest in older adults significantly attenuated the EAA-induced increase in MPS with a mechanism involving reduced mTORC1 signaling and amino acid transporter protein content. Together, our data suggest that a blunted EAA stimulation of MPS may contribute to muscle loss with inactivity in older persons.

Metastable aldehydes produced by lipid peroxidation act as 'toxic second messengers' that extend the injurious potential of free radicals. 4-hydroxy 2-nonenal (HNE), a highly toxic and most abundant stable end product of lipid peroxidation, has been implicated in the tissue damage, dysfunction, injury associated with aging and other pathological states such as cancer, Alzheimer, diabetes, cardiovascular and inflammatory complications. Further, HNE has been considered as a oxidative stress marker and it act as a secondary signaling molecule to regulates a number of cell signaling pathways. Biological activity of HNE depends on its intracellular concentration, which can differentially modulate cell death, growth and differentiation. Therefore, the mechanisms responsible for maintaining the intracellular levels of HNE are most important, not only in the defense against oxidative stress but also in the pathophysiology of a number of disease processes. In this review, we discussed the significance of HNE in mediating various disease processes and how regulation of its metabolism could be therapeutically effective.

The Paramyxovirus respiratory syncytial virus (RSV) is the primary etiologic agent of serious epidemic lower respiratory tract disease in infants, immunosuppressed patients, and the elderly. Lower tract infection with RSV is characterized by a pronounced peribronchial mononuclear infiltrate, with eosinophilic and basophilic degranulation. Because RSV replication is restricted to airway epithelial cells, where RSV replication induces potent expression of chemokines, the epithelium is postulated to be a primary initiator of pulmonary inflammation in RSV infection. The spectrum of RSV-induced chemokines expressed by alveolar epithelial cells has not been fully investigated. In this report, we profile the kinetics and patterns of chemokine expression in RSV-infected lower airway epithelial cells (A549 and SAE). In A549 cells, membrane-based cDNA macroarrays and high-density oligonucleotide probe-based microarrays identified inducible expression of CC (I-309, Exodus-1, TARC, RANTES, MCP-1, MDC, and MIP-1 alpha and -1 beta), CXC (GRO-alpha, -beta, and -gamma, ENA-78, interleukin-8 [IL-8], and I-TAC), and CX(3)C (Fractalkine) chemokines. Chemokines not previously known to be expressed by RSV-infected cells were independently confirmed by multiprobe RNase protection assay, Northern blotting, and reverse transcription-PCR. High-density microarrays performed on SAE cells confirmed a similar pattern of RSV-inducible expression of CC chemokines (Exodus-1, RANTES, and MIP-1 alpha and -1 beta), CXC chemokines (I-TAC, GRO-alpha, -beta, and -gamma, and IL-8), and Fractalkine. In contrast, TARC, MCP-1, and MDC were not induced, suggesting the existence of distinct genetic responses for different types of airway-derived epithelial cells. Hierarchical clustering by agglomerative nesting and principal-component analyses were performed on A549-expressed chemokines; these analyses indicated that RSV-inducible chemokines are ordered into three related expression groups. These data profile the temporal changes in expression by RSV-infected lower airway epithelial cells of chemokines, chemotactic proteins which may be responsible for the complex cellular infiltrate in virus-induced respiratory inflammation.

OBJECTIVES: To describe the amount and patterns of ambulatory activity in hospitalized older adults over consecutive hospital days. DESIGN: Observational cohort study. SETTING: University teaching hospital Acute Care for Elderly (ACE) unit. PARTICIPANTS: Adults aged 65 and older (N = 239) who wore a step activity monitor during their hospital stay. MEASUREMENTS: Total number of steps per 24-hour day. Mean daily steps were calculated based on number of days the step activity monitor was worn. RESULTS: Mean age was 76.6 ± 7.6; 55.1% of participants were female. Patients took a mean number of 739.7 (interquartile range 89-1,014) steps per day during their hospital stay. Patients with shorter stays tended to ambulate more on the first complete day of hospitalization and had a markedly greater increase in mobility on the second day than patients with longer lengths of stay. There were no significant differences in mean daily steps according to illness severity or reason for admission. CONCLUSION: Objective information on patient mobility can be collected for hospitalized older persons. Findings may increase understanding of the level of ambulation required to maintain functional status and promote recovery from acute illness.

PURPOSE OF REVIEW: We provide an update on the recent advances in nutrition research regarding the role of protein intake in the development and treatment of sarcopenia of aging. RECENT FINDINGS: Specific muscle mass, strength and function cut-points for the diagnosis of sarcopenia have been identified. There is mounting evidence, as highlighted by multiple consensus statements, that the Recommended Dietary Allowance (0.8 g/kg body weight) may be inadequate to promote optimal health in older adults. Recent research indicates that in addition to total daily protein intake the timing of protein intake is also important to best stimulate muscle protein synthesis, and maintain muscle mass and function in older adults. SUMMARY: Recent evidence suggests that the Recommended Dietary Allowance for protein is inadequate, and that the timing and distribution of protein consumption throughout daily meals may be as important as the total quantity. Research has continued to advance our understanding of protein's effects on muscle metabolism; however, there remains a need for large, long-term, randomized clinical trials examining whether the positive effects of dietary protein on muscle metabolism seen in acute studies will translate over the long term into gains of muscle mass, function, and the overall health of older adults.

In this study we found that, in 31 normal subjects, close to 90% of circulating arginine vasopressin (AVP), measured by radioimmunoassay, was associated with platelets. By using routine methods of centrifugation, which do not completely separate platelets, the normal range of plasma vasopressin was higher by twofold than the normal range in platelet-free plasma prepared by differential centrifugation, which was 1.4 +/- 1.0 sd pg/ml. Platelet vasopressin was 12.9 +/- 5.7 pg/ml. Patients with congestive heart failure had, on average, an elevated platelet-free plasma AVP, as did two patients with thrombocytopenia and one with thrombocytosis. Patients with essential hypertension had slightly high levels of platelet-free plasma AVP and demonstrated an abnormal inverse relationship between platelet-free plasma AVP and serum osmolality. Immunoreactive platelet vasopressin was slightly low in patients with essential hypertension and was subnormal in patients with congestive heart failure. These studies demonstrate that platelets normally present in centrifuged plasma cause an overestimation of the plasma vasopressin levels. Until the physiological meaning of plasma and platelet-bound AVP is understood, studies of circulating vasopressin should probably assess both plasma and platelet AVP levels.

Antibody cocktails represent a promising approach to prevent SARS-CoV-2 escape. The determinants for selecting antibody combinations and the mechanism that antibody cocktails prevent viral escape remain unclear. We compared the critical residues in the receptor-binding domain (RBD) used by multiple neutralizing antibodies and cocktails and identified a combination of two antibodies CoV2-06 and CoV2-14 for preventing viral escape. The two antibodies simultaneously bind to non-overlapping epitopes and independently compete for receptor binding. SARS-CoV-2 rapidly escapes from individual antibodies by generating resistant mutations in vitro, but it doesn't escape from the cocktail due to stronger mutational constraints on RBD-ACE2 interaction and RBD protein folding requirements. We also identified a conserved neutralizing epitope shared between SARS-CoV-2 and SARS-CoV for antibody CoV2-12. Treatments with CoV2-06 and CoV2-14 individually and in combination confer protection in mice. These findings provide insights for rational selection and mechanistic understanding of antibody cocktails as candidates for treating COVID-19.

Cryothermia, a new technique for definitive treatment of the pre-excitation syndrome, is described in two patients. The first patient presented with a normal P-R interval with a delta wave and reciprocating tachycardia. Preoperative electrophysiologic study suggested a free-wall atrioventricular connection on the left posterior atrioventricular (A-V) groove. At surgery, epicardial mapping confirmed the site of pre-excitation on the posterior left ventricular (LV) wall. An electrogram arising from the accessory pathway (AP) was recorded at the site of earliest ventricular activation. Interatrial delay combined with an apparently long accessory pathway to the ventricle caused the P-R interval to appear normal. Local pressure abolished pre-excitation. The site of early ventricular activation was cooled to -60 degrees C with a specially designed cryoprobe. All evidence of pre-excitation and arrhythmias disappeared. The second patient presented with a refractory reciprocating tachycardia and was found to have an AP in the septum capable of only retrograde conduction. Retrograde conduction was abolished by applying a temperature of 0 degrees C to the anulus at this site during tachycardia. Conduction over the AP and reciprocating tachycardia returned with rewarming. Ablation of the AP was obtained by applying a temperature of -60 degrees C for 90 seconds on two occasions to the same area. The His bundle was not injured.