Instruct-ERIC

The race to produce vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) began when the first sequence was published, and this forms the basis for vaccines currently deployed globally. Independent lineages of SARS-CoV-2 have recently been reported: UK, B.1.1.7; South Africa, B.1.351; and Brazil, P.1. These variants have multiple changes in the immunodominant spike protein that facilitates viral cell entry via the angiotensin-converting enzyme-2 (ACE2) receptor. Mutations in the receptor recognition site on the spike are of great concern for their potential for immune escape. Here, we describe a structure-function analysis of B.1.351 using a large cohort of convalescent and vaccinee serum samples. The receptor-binding domain mutations provide tighter ACE2 binding and widespread escape from monoclonal antibody neutralization largely driven by E484K, although K417N and N501Y act together against some important antibody classes. In a number of cases, it would appear that convalescent and some vaccine serum offers limited protection against this variant.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has undergone progressive change, with variants conferring advantage rapidly becoming dominant lineages, e.g., B.1.617. With apparent increased transmissibility, variant B.1.617.2 has contributed to the current wave of infection ravaging the Indian subcontinent and has been designated a variant of concern in the United Kingdom. Here we study the ability of monoclonal antibodies and convalescent and vaccine sera to neutralize B.1.617.1 and B.1.617.2, complement this with structural analyses of Fab/receptor binding domain (RBD) complexes, and map the antigenic space of current variants. Neutralization of both viruses is reduced compared with ancestral Wuhan-related strains, but there is no evidence of widespread antibody escape as seen with B.1.351. However, B.1.351 and P.1 sera showed markedly more reduction in neutralization of B.1.617.2, suggesting that individuals infected previously by these variants may be more susceptible to reinfection by B.1.617.2. This observation provides important new insights for immunization policy with future variant vaccines in non-immune populations.

Terminating the SARS-CoV-2 pandemic relies upon pan-global vaccination. Current vaccines elicit neutralizing antibody responses to the virus spike derived from early isolates. However, new strains have emerged with multiple mutations, including P.1 from Brazil, B.1.351 from South Africa, and B.1.1.7 from the UK (12, 10, and 9 changes in the spike, respectively). All have mutations in the ACE2 binding site, with P.1 and B.1.351 having a virtually identical triplet (E484K, K417N/T, and N501Y), which we show confer similar increased affinity for ACE2. We show that, surprisingly, P.1 is significantly less resistant to naturally acquired or vaccine-induced antibody responses than B.1.351, suggesting that changes outside the receptor-binding domain (RBD) impact neutralization. Monoclonal antibody (mAb) 222 neutralizes all three variants despite interacting with two of the ACE2-binding site mutations. We explain this through structural analysis and use the 222 light chain to largely restore neutralization potency to a major class of public antibodies.

SARS-CoV-2 has caused over 2 million deaths in little over a year. Vaccines are being deployed at scale, aiming to generate responses against the virus spike. The scale of the pandemic and error-prone virus replication is leading to the appearance of mutant viruses and potentially escape from antibody responses. Variant B.1.1.7, now dominant in the UK, with increased transmission, harbors 9 amino acid changes in the spike, including N501Y in the ACE2 interacting surface. We examine the ability of B.1.1.7 to evade antibody responses elicited by natural SARS-CoV-2 infection or vaccination. We map the impact of N501Y by structure/function analysis of a large panel of well-characterized monoclonal antibodies. B.1.1.7 is harder to neutralize than parental virus, compromising neutralization by some members of a major class of public antibodies through light-chain contacts with residue 501. However, widespread escape from monoclonal antibodies or antibody responses generated by natural infection or vaccination was not observed.

Anesthetic induction with propofol commonly results in hypotension. This study explored potential mechanisms contributing to hypotension by recording cardiovascular responses including sympathetic neural activity from patients during induction of anesthesia with propofol (2.5 mg.kg-1 plus 200 micrograms.kg-1.min-1) or, for comparison, etomidate (0.3 mg.kg-1 plus 15 micrograms.kg-1.min-1). Twenty-five consenting, nonpremedicated, ASA physical status 1 and 2, surgical patients were evaluated. Measurements of R-R intervals (ECG), blood pressure (radial artery), forearm vascular resistance (plethysmography), and efferent muscle sympathetic nerve activity ([MSNA] microneurography: peroneal nerve) were obtained at rest and during induction of anesthesia. In addition, a sequential bolus of nitroprusside (100 micrograms) followed by phenylephrine (150 micrograms) was used to obtain data to quantitate the baroreflex regulation of cardiac function (R-R interval) and sympathetic outflow (MSNA) in the awake and anesthetized states. Etomidate induction preserved MSNA, forearm vascular resistance, and blood pressure, whereas propofol reduced MSNA by 76 +/- 5% (mean +/- SEM), leading to a reduction in forearm vascular resistance and a significant hypotension. Both cardiac and sympathetic baroslopes were maintained with etomidate but were significantly reduced with propofol, especially in response to hypotension. These findings suggest that propofol-induced hypotension is mediated by an inhibition of the sympathetic nervous system and impairment of baroreflex regulatory mechanisms. Etomidate, conversely, maintains hemodynamic stability through preservation of both sympathetic outflow and autonomic reflexes.

< 0.1 μg/mL) blocking receptor interaction, except for one that binds a unique epitope in the N-terminal domain. Many of these neutralizing mAbs use public V-genes and are close to germline. We dissect the structural basis of recognition for this large panel of antibodies through X-ray crystallography and cryoelectron microscopy of 19 Fab-antigen structures. We find novel binding modes for some potently inhibitory antibodies and demonstrate that strongly neutralizing mAbs protect, prophylactically or therapeutically, in animal models.

Systolic pressure variation (SPV) is defined as the difference between the maximum and minimum values of systolic blood pressure following a single positive pressure breath. An increase in the SPV is known to occur clinically during hypovolemia. This study aims to quantify SPV during graded hemorrhage in ventilated dogs, and to compare its reliability relative to other hemodynamic indicators of hypovolemia. Ten anesthetized dogs were mechanically ventilated with a fixed tidal volume. A continuously inflated vest was applied around the chest to maintain the ratio of lung to chest wall compliance similar to that of humans (0.83 +/- 0.12). SPV was further divided into delta up and delta down components relative to apneic (5 s) systolic blood pressure. Dogs were bled 5, 10, 20, and 30% of their estimated blood volume. The measured parameters best correlated to the amount of bleeding were SPV (rs = 0.993), delta down (rs = 0.981), and cardiac output (rs = 0.976). The SPV and its delta down component correlated to the degree of hemorrhage as well as the CO and the pulmonary capillary wedge pressure, and significantly better than the central venous pressure and the mean systemic blood pressure. Thus, SPV and its delta down component are accurate indicators of hypovolemia in ventilated dogs subjected to hemorrhage.

There are as yet no licensed therapeutics for the COVID-19 pandemic. The causal coronavirus (SARS-CoV-2) binds host cells via a trimeric spike whose receptor binding domain (RBD) recognizes angiotensin-converting enzyme 2, initiating conformational changes that drive membrane fusion. We find that the monoclonal antibody CR3022 binds the RBD tightly, neutralizing SARS-CoV-2, and report the crystal structure at 2.4 Å of the Fab/RBD complex. Some crystals are suitable for screening for entry-blocking inhibitors. The highly conserved, structure-stabilizing CR3022 epitope is inaccessible in the prefusion spike, suggesting that CR3022 binding facilitates conversion to the fusion-incompetent post-fusion state. Cryogenic electron microscopy (cryo-EM) analysis confirms that incubation of spike with CR3022 Fab leads to destruction of the prefusion trimer. Presentation of this cryptic epitope in an RBD-based vaccine might advantageously focus immune responses. Binders at this epitope could be useful therapeutically, possibly in synergy with an antibody that blocks receptor attachment.

Background Although the effects of propofol on cerebral metabolism have been studied in animals, these effects have yet to be directly examined in humans. Consequently, we used positron emission tomography (PET) to demonstrate in vivo the regional cerebral metabolic changes that occur in humans during propofol anesthesia. Methods Six volunteers each underwent two PET scans; one scan assessed awake-baseline metabolism, and the other assessed metabolism during anesthesia with a propofol infusion titrated to the point of unresponsiveness (mean rate +/- SD = 7.8 +/- 1.5 mg.kg-1.h-1). Scans were obtained using the 18fluorodeoxyglucose technique. Results Awake whole-brain glucose metabolic rates (GMR) averaged 29 +/- 8 mumoles.100 g-1.min-1 (mean +/- SD). Anesthetized whole-brain GMR averaged 13 +/- 4 mumoles.100 g-1.min-1 (paired t test, P &lt; or = 0.007). GMR decreased in all measured areas during anesthesia. However, the decrease in GMR was not uniform. Cortical metabolism was depressed 58%, whereas subcortical metabolism was depressed 48% (P &lt; or = 0.001). Marked differences within cortical regions also occurred. In the medial and subcortical regions, the largest percent decreases occurred in the left anterior cingulate and the inferior colliculus. Conclusion Propofol produced a global metabolic depression on the human central nervous system. The metabolic pattern evident during anesthesia was reproducible and differed from that seen in the awake condition. These findings are consistent with those from previous animal studies and suggest PET may be useful for investigating the mechanisms of anesthesia in humans.

BACKGROUND: Cardiovascular instability after intravenous induction of anesthesia may be explained partly by direct negative inotropic effects. The direct inotropic influence of etomidate, ketamine, midazolam, propofol, and thiopental on the contractility of isolated human atrial tissue was determined. Effective concentrations were compared with those reported clinically. METHODS: Atrial tissue was obtained from 16 patients undergoing coronary bypass surgery. Each fragment was divided into three strips, and one anesthetic was tested per strip in increasing concentrations (10(-6) to 10(-2) M). Strips were stimulated at 0.5 Hz, and maximum isometric force was measured. Induction agents were studied in two groups, group 1 (n = 7) containing thiopental, midazolam, and propofol, and group 2 (n = 9) consisting of etomidate, ketamine, and propofol. RESULTS: The tested anesthetics caused a concentration-dependent depression of contractility resulting in complete cessation of contractions at the highest concentrations. The IC50s (mean +/- SEM; microM) for inhibition of the contractility were: thiopental 43 +/- 7.6, propofol 235 +/- 48 (group 1), and 246 +/- 42 (group 2), midazolam 145 +/- 54, etomidate 133 +/- 13, and ketamine 303 +/- 54. CONCLUSIONS: This is the first study demonstrating a concentration-dependent negative inotropic effect of intravenous anesthetics in isolated human atrial muscle. No inhibition of myocardial contractility was found in the clinical concentration ranges of propofol, midazolam, and etomidate. In contrast, thiopental showed strong and ketamine showed slight negative inotropic properties. Thus, negative inotropic effects may explain in part the cardiovascular depression on induction of anesthesia with thiopental but not with propofol, midazolam, and etomidate. Improvement of hemodynamics after induction of anesthesia with ketamine cannot be explained by intrinsic cardiac stimulation.

Perry, M. O. M.D., F.A.C.S.; Thal, Erwin R. M.D.; Shires, G. Tom M.D., F.A.C.S. Author Information

BACKGROUND: Changes in basal temperature of > or = 1 degree C (e.g., fever-induced hyperthermia or anesthesia-related hypothermia) are a common occurrence in neurologically impaired patients. The current study tested the hypothesis that temperature changes as small as 1 degree C or 2 degrees C would significantly alter post-ischemic functional neurologic outcome and cerebral histopathology. The hypothesis was tested in a canine model of transient, complete cerebral ischemia. METHODS: After institutional approval, 21 dogs were randomly assigned to one of three temperature-specific groups: (1) a reference group maintained at 37.0 +/- 0.3 degree C (target temperature +/- range); (2) a 38.0 +/- 0.3 degree C group; or (3) a 39.0 +/- 0.3 degree C group (n = 7 per group). Complete cerebral ischemia 12.5 min in duration was produced using an established model of arterial hypotension plus intracranial hypertension. Right atrial and cranial (beneath the temporalis muscles) temperatures were maintained at the target value, beginning 20 min before ischemia and ceasing 1 h postischemia. Thereafter, temperatures were returned to 37.0 +/- 0.3 degree C in all dogs. After discharge from the intensive care environment, all dogs were placed in a temperature-controlled recovery area. Neurologic assessment was performed by a blinded observer at 24, 48, and 72 h postischemia using a 100-point scoring scale. After the 72 h examination (with the dogs anesthetized) or at the time of ischemia-related death, the brains were excised and preserved. The brains subsequently were histologically scored by a neuropathologist who was unaware of the treatment groups. All 21 dogs were included in the analysis of neurologic function; however, only dogs that survived for > or = 24 h postischemia were included in the histopathology analysis. RESULTS: Dogs were well matched for systemic physiologic variables throughout the study, with the exception of temperature. During the 72 h postischemic examination, dogs maintained at 37 degrees C were either normal or near normal. In contrast, dogs maintained at 39 degrees C were either comatose or died from ischemia-related causes. Dogs maintained at 38 degrees C were intermediate between 37 degrees C and 39 degrees C dogs. When compared with the reference group, both 38 degrees C and 39 degrees C dogs had significantly worse neurologic function scores (P < 0.01 and < 0.001, respectively) and histopathology scores (P < 0.01 for both). There also was a significant correlation between neurologic function and histopathology rank scores (rs = 0.96; P < 0.001). CONCLUSIONS: Small, clinically relevant changes in temperature (1 degree C or 2 degrees C) resulted in significant alterations in both postischemic neurologic function and cerebral histopathology. Assuming that our results are transferable to humans, the results suggest that, in patients at imminent risk for ischemic neurologic injury, body temperature should be closely monitored. Further, the clinician should aggressively treat all episodes of hyperthermia until the patient is no longer at risk for ischemic neurologic injury.

A series of 51 patients treated with 92 separate lung fields for metastatic pulmonary disease between 1958 and 1971 is reviewed. The treatment data are converted into nominal single doses (NSD) and a newly derived formula for estimated single doses (ED). The 5% incidence level of pneumonitis without dactinomycin is 770 rets (NSD) and 510 rets (ED) and with dactinomycin, 520 rets (NSD) and 450 rets (ED). A safe treatment regimen for avoiding radiation pneumonitis is 1500 rads in 10 fractions with dactinomycin and 2500 rads in 20 fractions without dactinomycin.

The authors studied the effect of thiopental in ameliorating permanent brain damage in monkeys after 16 min of global ischemia of the brain produced by a high-pressure neck tourniquet and systemic arterial hypotension. Intensive care and life support, including monitoring of physiologic variables, w

Abstract This article summarizes the current evidence for the use of gabapentinoids in the perioperative setting and provides useful clinical recommendations regarding dosing, timing, and choice of agent.

BACKGROUND: The postoperative period is associated with increased production of proinflammatory cytokines, which are known to augment pain sensitivity, among other effects. In a previous study, the authors found that patients treated with patient-controlled epidural analgesia (PCEA) exhibited attenuated proinflammatory cytokine response in the postoperative period. In the present study, the authors examined whether preemptive analgesia continued with PCEA may further attenuate the proinflammatory cytokine response and reduce pain sensitivity in the postoperative period. They compared cytokine production in two groups of patients, one receiving PCEA, the other receiving preemptive epidural analgesia continued by PCEA. METHODS: Female patients hospitalized for transabdominal hysterectomy were randomly assigned to one of two pain management techniques: PCEA or preemptive epidural analgesia followed by PCEA (PA + PCEA). Postoperative pain was assessed using the visual analog scale. Blood samples were collected before, 24, 48, and 72 h following surgery. Production of the following cytokines was assessed in stimulated peripheral blood mononuclear cells: interleukin (IL)-1beta, tumor necrosis factor alpha, IL-6, IL-1ra, IL-10, and IL-2. RESULTS: Patients of the PA + PCEA group exhibited lower pain scores throughout the 72 h postoperatively, compared with patients of the PCEA group. In patients of the PA + PCEA group in the postoperative period, production of IL-1beta, IL-6, IL-1ra, and IL-10 was significantly less elevated, while IL-2 production was significantly less suppressed. CONCLUSIONS: Proinflammatory cytokines are key mediators of illness symptoms, including hyperalgesia. The present results suggest that preemptive epidural analgesia is associated with reduced postoperative pain and attenuated production of proinflammatory cytokines.

Life sciences are yielding huge data sets that underpin scientific discoveries fundamental to improvement in human health, agriculture and the environment. In support of these discoveries, a plethora of databases and tools are deployed, in technically complex and diverse implementations, across a spectrum of scientific disciplines. The corpus of documentation of these resources is fragmented across the Web, with much redundancy, and has lacked a common standard of information. The outcome is that scientists must often struggle to find, understand, compare and use the best resources for the task at hand.Here we present a community-driven curation effort, supported by ELIXIR-the European infrastructure for biological information-that aspires to a comprehensive and consistent registry of information about bioinformatics resources. The sustainable upkeep of this Tools and Data Services Registry is assured by a curation effort driven by and tailored to local needs, and shared amongst a network of engaged partners.As of November 2015, the registry includes 1785 resources, with depositions from 126 individual registrations including 52 institutional providers and 74 individuals. With community support, the registry can become a standard for dissemination of information about bioinformatics resources: we welcome everyone to join us in this common endeavour. The registry is freely available at https://bio.tools.

* Research Trainee, Dept. of Anesthesia, Univ. of Calif. Medical Center, San Francisco (Present address: Dept. of Anesthesiology, Univ. of Miami, Miami, Florida).† Associate Professor.‡ Assistant Professor (Present address: Dept. of Anesthesia, Univ. of California, Davis).pR; Research Trainee (Lederle Fellow), Department of Anesthesia, University of California Medical Center, San Francisco (Present address: American University, Beirut, Lebanon).

The relative risk of shunting versus not shunting during carotid endarterectomy was analyzed retrospectively in 1935 cases undergoing carotid endarterectomy for carotid ulcerative stenosis. The need for shunting was based on a correlation between electroencephalographic changes and a fall in cerebral blood flow below the critical level required for adequate perfusion during the period of carotid occlusion. Patients were divided into four risk categories for surgery, based on medical and neurological risks and angiographic findings. Shunts were required in 30% of the low risk group and 56% of the high risk group. Based on the severity of reductions of cerebral blood flow during the period of carotid occlusion it is concluded that 12% of all patients would have sustained a major deficit, 15% a minor or transient deficit, and 20% a transient deficit without shunting. The risk of shunting 792 cases in this series was 0.5%. Overall minor morbidity, major morbidity, and mortality each approximated 1% in this series.

Changes in cerebral blood flow (CBF) in response to changes in PaCO2 were measured by intraaortic injection of 133Xe in 12 patients during hypothermic (23-30 degrees C) cardiopulmonary bypass. In each patient, CBF was determined at two randomly ordered levels of PaCO2 obtained by varying the rate of gas inflow into the pump oxygenator (Group I, n = 6) or by varying the percentage of CO2 added to the gas inflow (Group II, n = 6). Nasopharyngeal temperature, mean arterial pressure, pump-oxygenator flow, and hematocrit were maintained within a narrow range. In group I, a PaCO2 (uncorrected for body temperature) of 36 +/- 4 mmHg (mean +/- SD) was associated with a CBF of 13 +/- 5 ml X 100 g-1 X min-1, while a PaCO2 of 42 +/- 4 mmHg was associated with a CBF of 19 +/- 10 ml X 100 g-1 X min-1. In group II, a PaCO2 of 47 +/- 3 mmHg was associated with a CBF of 20 +/- 8 ml X 100 g-1 X min-1, and a PaCO2 of 53 +/- 3 mmHg was associated with a CBF of 26 +/- 9 ml X 100 g-1 X min-1. Within group I, the difference in CBF was significant (P less than 0.05); within group II, the difference in CBF was significant at the P less than 0.002 level. All CBF measurements were lower than those reported for normothermic, unanesthetized subjects of similar age.(ABSTRACT TRUNCATED AT 250 WORDS)