Ultrastructure of cholinergic synaptic terminals in the thalamic anteroventral,ventroposterior, and dorsal lateral geniculate nuclei of the rat

The principal relay nuclei of the thalamus receive their cholinergic innervation from two midbrain cholinergic groups: the pedunculopontine tegmental nucleus and the laterodorsal tegmental nucleus. The different thalamic nuclei exhibit populations of cholinergic axons which vary in density and morphology when examined at the light microscopic level. However, the ultrastructure of the cholinergic terminals in different thalamic nuclei has not been described. This study was undertaken to confirm that synaptic contacts are formed by cholinergic axons in several principal thalamic relay nuclei, to describe their ultrastructural morphology, and to identify the types of postsynaptic elements contacted by cholinergic synaptic terminals. The thalamic nuclei examined in this study are the dorsal lateral geniculate nucleus, ventroposteromedial nucleus, ventroposterolateral nucleus, and anteroventral nucleus. Our results confirm that cholinergic axons form synaptic terminals in these thalamic nuclei. Cholinergic synaptic terminals contact structures outside the characteristic synaptic glomeruli, are never postsynaptic, and have morphologies and postsynaptic targets which differ among the thalamic nuclei. In the ventroposterior nuclei, cholinergic terminals form asymmetric synaptic contacts onto larger dendrites in the extraglomerular neuropil. In the anteroventral nucleus, cholinergic terminals form both symmetric and asymmetric synaptic contacts onto dendrites and somata. Cholinergic terminals in the anteroventral nucleus are larger than those in other nuclei. In the dorsal lateral geniculate nucleus, cholinergic terminals contact both somata and dendrites in the extraglomerular neuropil, but the synaptic contacts in this nucleus are symmetric in morphology.     

All-cause and cardiovascular mortality among diabetic participants in the San Antonio Heart Study: evidence against the "Hispanic Paradox"

OBJECTIVE: The observation that Hispanics have lower all-cause and cardiovascular mortality, despite increased diabetes and obesity, lower socioeconomic status (SES), and barriers to health care, has been termed the "Hispanic Paradox." We examined the relationship between ethnicity and all-cause and cardiovascular mortality in Mexican Americans (MAs) and non-Hispanic whites (NHWs) with diabetes. RESEARCH DESIGN AND METHODS: In the San Antonio Heart Study, a prospective cohort, we compared the mortality in 554 U.S.-born MAs, 95 Mexico-born MAs, and 178 NHW participants with diabetes aged 25-72 years. Over an average of 10.4 years, 188 deaths occurred: 115 from cardiovascular disease (CVD) [death certificate ICD-9 codes 401-414 or 420-447 (excluding 427.5)]. Because of potential differences between migrants and nonmigrants, hazard ratios (HRs) were calculated comparing U.S.-born MAs and Mexico-born MAs with NHWs. RESULTS: The age- and sex-adjusted HR for all-cause mortality comparing U.S.-born MAs with NHWs was 1.66 (95% CI 1.15-2.40), while comparing Mexico-born MAs with NHWs was 1.14 (95% CI 0.63-2.06). Cardiovascular mortality HRs were 1.66 (95% CI 1.04-2.65) and 0.89 (95% CI 0.40-2.01), respectively. After adjusting for possible confounders, such as fasting glucose and diabetes duration, the hazard of all-cause and cardiovascular mortality (although not statistically significant) appeared higher in U.S.-born MAs than in the other two groups. CONCLUSIONS: We found it important to differentiate MAs by birthplace. Among diabetic participants, contrary to the prediction of the "Hispanic Paradox," compared with NHWs, U.S.-born MAs were at greater risk of all-cause and cardiovascular mortality, while Mexico-born MAs appeared to be at similar risk.     

Antagonist HIV-1 Gag Peptides Induce Structural Changes in HLA B8

In the cellular immune response, recognition by CTL-TCRs of viral antigens presented as peptides by HLA class I molecules, triggers destruction of the virally infected cell (Townsend, A.R.M., J. Rothbard, F.M. Gotch, G. Bahadur, D. Wraith, and A.J. McMichael. 1986. Cell. 44:959–968). Altered peptide ligands (APLs) which antagonise CTL recognition of infected cells have been reported (Jameson, S.C., F.R. Carbone, and M.J. Bevan. 1993. J. Exp. Med. 177:1541–1550). In one example, lysis of antigen presenting cells by CTLs in response to recognition of an HLA B8–restricted HIV-1 P17 (aa 24–31) epitope can be inhibited by naturally occurring variants of this peptide, which act as TCR antagonists (Klenerman, P., S. Rowland Jones, S. McAdam, J. Edwards, S. Daenke, D. Lalloo, B. Koppe, W. Rosenberg, D. Boyd, A. Edwards, P. Giangrande, R.E. Phillips, and A. McMichael. 1994. Nature (Lond.). 369:403– 407). We have characterised two CTL clones and a CTL line whose interactions with these variants of P17 (aa 24–31) exhibit a variety of responses. We have examined the high resolution crystal structures of four of these APLs in complex with HLA B8 to determine alterations in the shape, chemistry, and local flexibility of the TCR binding surface. The variant peptides cause changes in the recognition surface by three mechanisms: changes contributed directly by the peptide, effects transmitted to the exposed peptide surface, and induced effects on the exposed framework of the peptide binding groove. While the first two mechanisms frequently lead to antagonism, the third has more profound effects on TCR recognition.Residues 24–31 (GGKKKYKL) of the HIV-1 Gag protein p17, a region overlapping the nuclear localization site (1), have been mapped as an HLA B8–restricted epitope capable of eliciting a CTL response in HIV-1 seropositive individuals (2). Variations in the genetic sequence encoding these residues have been detected in viruses isolated from patients making a CTL response to this epitope (2, 3). Our present study focuses on four peptides which are related to the index peptide (GGKKKYKL) by single residue changes corresponding to naturally occurring variant epitope sequences, each of which has occured in more than one HLA B8 positive, HIV infected patient (Table ​(Table1,1, denoted as 3R, 5R, 7R, and 7Q). The index and variant peptides bind HLA B8 with similar affinities in vitro (4). A number of CTL clones and lines specific for this epitope have been generated from two HIV positive donors. Fig. ​Fig.11 shows data from two clones and a line demonstrating the effects that these substitutions can have in terms of recognition and antagonism. The differences between the index and the four variant HLA B8–peptide complexes have been analysed in a series of x-ray crystallographic structure determinations at 2.3 Å resolution or better. Crystallographic statistics for each of the complexes are detailed in Table ​Table1.1. In line with the binding motif deduced from several epitopes and pooled peptide sequences (5), the index peptide (residues P1–P8) is anchored in the HLA B8–binding groove by buried lysine residues at peptide positions P3 and P5 and by the COOHterminal (P8 or PC) leucine residue (see Fig. ​Fig.2).2). Conversely, the sidechains of residues P4, P7 and P6, contribute to the surface exposed for TCR recognition. The APLs thus encompass changes at residues directly exposed to TCR recognition (P7) and at buried anchor residues (P3 and P5).

Table 1

Statistics for Crystallographic Structure Determination

The relationship between distance to hospital and patient mortality in emergencies: an observational study

Objectives

Reconfiguration of emergency services could lead to patients with life‐threatening conditions travelling longer distances to hospital. Concerns have been raised that this could increase the risk of death. We aimed to determine whether distance to hospital was associated with mortality in patients with life‐threatening emergencies.

Methods

We undertook an observational cohort study of 10 315 cases transported with a potentially life‐threatening condition (excluding cardiac arrests) by four English ambulance services to associated acute hospitals, to determine whether distance to hospital was associated with mortality, after adjustment for age, sex, clinical category and illness severity.

Results

Straight‐line ambulance journey distances ranged from 0 to 58 km with a median of 5 km, and 644 patients died (6.2%). Increased distance was associated with increased risk of death (odds ratio 1.02 per kilometre; 95% CI 1.01 to 1.03; p<0.001). This association was not changed by adjustment for confounding by age, sex, clinical category or illness severity. Patients with respiratory emergencies showed the greatest association between distance and mortality.

Conclusion

Increased journey distance to hospital appears to be associated with increased risk of mortality. Our data suggest that a 10‐km increase in straight‐line distance is associated with around a 1% absolute increase in mortality.     

Patient and Primary Care Physician Satisfaction with Chest Pain Unit and Routine Care

OBJECTIVES: The chest pain unit (CPU) has been developed to improve care for patients with acute, undifferentiated chest pain. The authors aimed to measure patient and primary care physician (PCP) satisfaction with CPU care and routine care and to determine whether patient satisfaction predicted PCP satisfaction. METHODS: A CPU was established, and 442 days were randomly allocated to either CPU care or routine care. Consenting patients presenting with acute, undifferentiated chest pain were recruited and followed at two days and one month. All were given a self-completed patient satisfaction questionnaire two days after attendance (N = 972). Each patient's PCP was sent a self-completed satisfaction questionnaire during days 171-442 of the trial (N = 601). Analysis determined whether CPU care was associated with improved patient or PCP satisfaction and whether patient satisfaction predicted PCP satisfaction for three questions relating to diagnosis, treatment, and overall care. RESULTS: CPU care was consistently associated with higher scores across all patient satisfaction questions, from the perceived thoroughness of examination to care received to an overall assessment of the service received. However, CPU care achieved small improvements in only two of ten PCP satisfaction questions, concerning overall management of the patient and the amount of information about investigations performed. Furthermore, patient satisfaction did not predict PCP satisfaction in relation to diagnosis (p = 0.456), treatment (p = 0.256), or overall care (p = 0.085). CONCLUSIONS: CPU care is associated with substantial improvements in all dimensions of patient satisfaction but only minimal improvements in PCP satisfaction. Patient satisfaction was not a strong predictor of PCP satisfaction with emergency care.     

Conversion of atrial fibrillation to sinus rhythm during treatment with intravenous esmolol or diltiazem: a prospective, randomized comparison

Prior studies have suggested that intravenous diltiazem reduces the probability of spontaneous conversion of atrial fibrillation (AF) to sinus rhythm in the electrophysiology laboratory and in patients with postoperative AF. Whether diltiazem exerts the same effect in patients presenting to the emergency department (ED) with spontaneous AF is unclear. Fifty patients presenting to the ED with new-onset or paroxysmal AF and a rapid ventricular rate (>100 beats per minute) were randomly assigned to receive intravenous diltiazem or esmolol during the first 24 hours of presentation. Conversion to sinus rhythm occurred in 10 patients (42%) in the diltiazem group compared with 10 patients (39%) in the esmolol group (P = 1.0). Diltiazem does not decrease the likelihood of spontaneous conversion of AF to sinus rhythm in the ED setting.     

Early intervention in migraine with sumatriptan tablets 50 mg versus 100 mg: a pooled analysis of data from six clinical trials

BACKGROUND: In clinical trials evaluating sumatriptan in the treatment of moderate or severe migraine pain, the 50- and 100-mg doses have been comparably effective and well tolerated. OBJECTIVE: To assess the dose-efficacy relationship of sumatriptan tablets given early for mild pain, data from 6 randomized, double-blind, placebo-controlled, early-intervention studies of sumatriptan tablets 50 mg and 100 mg (5 of which have been published) were pooled for analysis. These constitute all the studies conducted to date of sumatriptan tablets prospectively given early for mild pain. METHODS: The primary efficacy end point in all the studies was the proportion of patients reporting a pain-free result (ie, mild, moderate, or severe pain reduced to none) 2 hours postdose. Other efficacy end points included the proportion of patients who were migraine free (ie, no pain and no associated symptoms of nausea, vomiting, photophobia, or phonophobia) 2 hours postdose; the proportion reporting worsening of pain (ie, moderate or severe pain) 2 hours postdose; and the proportion with a sustained pain-free result (ie, pain free from 2-24 hours postdose with no use of a second dose of study medication or of rescue medication). Tolerability was assessed by evaluating the incidence of individual adverse events. The investigators assessed each adverse event's relationship to study medication. RESULTS: The number of patients in the intent-to-treat population was 2297 (771 sumatriptan 50 mg, 759 sumatriptan 100 mg, 767 placebo). Patients' mean age ranged from 39.4 to 39.8 years across groups, and most patients were female (90%-92%) and white (89%-90%). A pain-free result 2 hours post dose was reported by significantly more patients who took either dose of sumatriptan tablets compared with placebo and by significantly more patients who took the 100-mg dose compared with the 50-mg dose (50 mg, 49%; 100 mg, 58%; placebo, 24%; P < 0.001, both sumatriptan doses vs placebo, and 100 mg vs 50 mg). A similar pattern was observed for migraine-free results 2 hours postdose (50 mg, 42%; 100 mg, 47%; placebo, 20%; P < 0.05, both sumatriptan doses vs placebo, and 100 mg vs 50 mg), worsening of pain 2 hours postdose (50 mg, 26%; 100 mg, 21%; placebo, 46%; P < 0.05, both sumatriptan doses vs placebo, and 100 mg vs 50 mg), and sustained pain-free results from 2 through 24 hours postdose (50 mg, 30%; 100 mg, 35%; placebo, 12%; P < 0.05, both sumatriptan doses vs placebo, and 100 mg vs 50 mg). Both doses of sumatriptan were well tolerated, and no dose-related trends in the incidence of individual drug-related adverse events were observed. CONCLUSIONS: In this analysis of pooled data from 6 clinical trials, sumatriptan tablets 50 mg and 100 mg administered early in a migraine attack while the pain was mild were well tolerated and significantly more effective than placebo. The 100-mg dose of sumatriptan was significantly more effective than the 50-mg dose.     

Novel nonnucleoside inhibitor of hepatitis C virus RNA-dependent RNA polymerase

A novel nonnucleoside inhibitor of hepatitis C virus (HCV) RNA-dependent RNA polymerase (RdRp), [(1R)-5-cyano-8-methyl-1-propyl-1,3,4,9-tetrahydropyano[3,4-b]indol-1-yl] acetic acid (HCV-371), was discovered through high-throughput screening followed by chemical optimization. HCV-371 displayed broad inhibitory activities against the NS5B RdRp enzyme, with 50% inhibitory concentrations ranging from 0.3 to 1.8 microM for 90% of the isolates derived from HCV genotypes 1a, 1b, and 3a. HCV-371 showed no inhibitory activity against a panel of human polymerases, including mitochondrial DNA polymerase gamma, and other unrelated viral polymerases, demonstrating its specificity for the HCV polymerase. A single administration of HCV-371 to cells containing the HCV subgenomic replicon for 3 days resulted in a dose-dependent reduction of the steady-state levels of viral RNA and protein. Multiple treatments with HCV-371 for 16 days led to a >3-log10 reduction in the HCV RNA level. In comparison, multiple treatments with a similar inhibitory dose of alpha interferon resulted in a 2-log10 reduction of the viral RNA level. In addition, treatment of cells with a combination of HCV-371 and pegylated alpha interferon resulted in an additive antiviral activity. Within the effective antiviral concentrations of HCV-371, there was no effect on cell viability and metabolism. The intracellular antiviral specificity of HCV-371 was demonstrated by its lack of activity in cells infected with several DNA or RNA viruses. Fluorescence binding studies show that HCV-371 binds the NS5B with an apparent dissociation constant of 150 nM, leading to high selectivity and lack of cytotoxicity in the antiviral assays.     

The Clinical Genome Resource (ClinGen) Familial Hypercholesterolemia Variant Curation Expert Panel consensus guidelines for LDLR variant classification

PurposeIn 2015, the American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP) published consensus standardized guidelines for sequence-level variant classification in Mendelian disorders. To increase accuracy and consistency, the Clinical Genome Resource Familial Hypercholesterolemia (FH) Variant Curation Expert Panel was tasked with optimizing the existing ACMG/AMP framework for disease-specific classification in FH. In this study, we provide consensus recommendations for the most common FH-associated gene, LDLR, where >2300 unique FH-associated variants have been identified.MethodsThe multidisciplinary FH Variant Curation Expert Panel met in person and through frequent emails and conference calls to develop LDLR-specific modifications of ACMG/AMP guidelines. Through iteration, pilot testing, debate, and commentary, consensus among experts was reached.ResultsThe consensus LDLR variant modifications to existing ACMG/AMP guidelines include (1) alteration of population frequency thresholds, (2) delineation of loss-of-function variant types, (3) functional study criteria specifications, (4) cosegregation criteria specifications, and (5) specific use and thresholds for in silico prediction tools, among others.ConclusionEstablishment of these guidelines as the new standard in the clinical laboratory setting will result in a more evidence-based, harmonized method for LDLR variant classification worldwide, thereby improving the care of patients with FH.     

Prevalence of Rotator Cuff Repairs with and Without Concomitant Subacromial Decompressions Has Not Changed

Background

Recent research from the American Board of Orthopaedic Surgery database indicates a decreasing rate of subacromial decompression (SAD) performed with rotator cuff repair (RCR) by younger orthopedic surgeons.

Questions/Purposes

The purpose of this study was to determine the rate of RCR with and without SAD and whether the rate of RCR with SAD decreased over time. Further, we set out to determine if there was significant variation in the rate of RCR with SAD by state.

Methods

Rates of RCR with and without open or arthroscopic SAD from 2010 to 2012 were determined based upon de-identified data from a national health insurance carrier. Data were normalized per 10,000 insured patients for comparative analysis.

Results

Rates of RCR with concomitant SAD were higher than RCR without SAD in each year analyzed. In patients 50 years old and older, this same significant difference was also seen for each year. The rate of RCR with or without SAD did not decrease over the 3-year time period. The rate of RCR performed concomitantly with SAD was significantly higher than RCR performed without SAD in all patient age groups combined. There was wide variation in the rate of RCR with or without concurrent SAD across states.

Conclusion

Disproving our hypothesis, the overall rate of RCR with or without SAD did not decrease over the period from 2010 to 2012. There was wide variation in the rate of RCR by state; however, this variation was not seen in the incidence of SAD performed concomitant with the RCR.