Simultaneous Recruitment of Drug Users and Men Who Have Sex with Men in the United States and Russia Using Respondent-Driven Sampling: Sampling Methods and Implications

The Sexual Acquisition and Transmission of HIV Cooperative Agreement Program (SATHCAP) examined the role of drug use in the sexual transmission of the human immunodeficiency virus (HIV) from traditional high-risk groups, such as men who have sex with men (MSM) and drug users (DU), to lower risk groups in three US cities and in St. Petersburg, Russia. SATHCAP employed respondent-driven sampling (RDS) and a dual high-risk group sampling approach that relied on peer recruitment for a combined, overlapping sample of MSM and DU. The goal of the sampling approach was to recruit an RDS sample of MSM, DU, and individuals who were both MSM and DU (MSM/DU), as well as a sample of sex partners of MSM, DU, and MSM/DU and sex partners of sex partners. The approach efficiently yielded a sample of 8,355 participants, including sex partners, across all four sites. At the US sites—Los Angeles, Chicago, and Raleigh–Durham—the sample consisted of older (mean age = 41 years), primarily black MSM and DU (both injecting and non-injecting); in St. Petersburg, the sample consisted of primarily younger (mean age = 28 years) MSM and DU (injecting). The US sites recruited a large proportion of men who have sex with men and with women, an important group with high potential for establishing a generalized HIV epidemic involving women. The advantage of using the dual high-risk group approach and RDS was, for the most part, the large, efficiently recruited samples of MSM, DU, and MSM/DU. The disadvantages were a recruitment bias by race/ethnicity and income status (at the US sites) and under-enrollment of MSM samples because of short recruitment chains (at the Russian site)

Revelations About Carotid Body Function Through its Pathological Role in Resistant Hypertension

Much recent attention has been given to the carotid body because of its potential role in cardiovascular disease states. One disease, neurogenic hypertension, characterised by excessive sympathetic activity, appears dependent on carotid body activity that may or may not be accompanied by sleep-disordered breathing. Herein, we review recent literature suggesting that the carotid body acquires tonicity in hypertension. We predict that carotid glomectomy will be a powerful way to temper excessive sympathetic discharge in diseases such as hypertension. We propose a model to explain that signalling from the ‘hypertensive’ carotid body is tonic, and hypothesise that there will be a sub-population of glomus cells that channel separately into reflex pathways controlling sympathetic motor outflows

HISTAMINE RECEPTOR-MEDIATED SUSTAINED POST-EXERCISE VASODILATION IN YOUNG TRAINED AND UNTRAINED ADULTS

M.J. Luttrell, P.M. Abdala, M.R. Ely, D.C. Sieck, J.E. Mangum, J.R. Halliwill FACSM University of Oregon, Eugene, OR Histamine-mediated sustained post-exercise vasodilation in response to one hour of dynamic knee extension has been established in young, recreationally active adults. It is unknown whether endurance exercise training modifies this response in young adults. PURPOSE: The purpose of this study was to test the hypothesis that sedentary young adults have similar histamine receptor mediated sustained post-exercise vasodilator responses compared to endurance trained young adults. METHODS: A randomized, double-blind placebo-controlled crossover study including 6 endurance trained (3F, 3M; ages 18-26) and 5 sedentary (3F, 2M; ages 22-29) adults was completed. Subjects consumed either combined histamine H1 and H2 receptor blockade with 540 mg fexofenadine (Allegra, H1 receptor blocker) and 300mg ranitidine (Zantac, H2 receptor blocker), or placebo pills containing only the inactive ingredients of fexofenadine and ranitidine. Pre-exercise vascular blood flow and conductance measurements were made every 30 minutes for 90 minutes. Post-exercise measurements were made every 30 minutes for 2 hours. Subjects completed 1 hour of dynamic knee extension exercise at 60% of maximal work rate. Subject demographics and baseline variables were analyzed using independent t-tests. Post-exercise differences between groups in the blockade and placebo conditions were analyzed using a mixed model ANOVA with repeated measures. All values are reported as mean ± SE. RESULTS: The endurance trained group had higher self-reported weekly physical activity compared to the sedentary group (73.03 ± 10.5 vs. 27.4 ± 9.5 METhr/wk, p=0.012). Pre-exercise mean arterial pressure was not different between the two groups in either placebo or blockade conditions (trained placebo: 83±2, trained blockade: 84±2, sedentary placebo: 84±1, sedentary blockade: 86±3 mmHg, p=0.745). Baseline femoral vascular conductance was not different between groups in either placebo or blockade condition (p=0.905). At 60 minutes post exercise, the change in femoral vascular conductance from baseline was not different between the groups for either placebo or blockade condition, although there was a trend towards drug effect of histamine receptor blockade (p=0.192). CONCLUSION: These preliminary results suggest that there is no difference in post-exercise femoral vascular conductance between endurance trained and sedentary young adults. Supported by NIH grant HL115027

Understanding the anomalous behavior of Vegard's law in Ce1-: XMxO2 (M = Sn and Ti; 0 < x ≤ 0.5) solid solutions},

The dependence of the lattice parameter on dopant concentration in Ce1−xMxO2 (M = Sn and Ti) solid solutions is not linear. A change towards a steeper slope is observed around x ∼ 0.35, though the fluorite structure (space group Fm3m) is preserved up to x = 0.5. This phenomenon has not been observed for Ce1−xZrxO2 solid solutions showing a perfectly linear decrease of the lattice parameter up to x = 0.5. In order to understand this behavior, the oxidation state of the metal ions, the disorder in the oxygen substructure and the nature of metal–oxygen bonds have been analyzed by XPS, 119Sn Mössbauer spectroscopy and X-ray absorption spectroscopy. It is observed that the first Sn–O coordination shell in Ce1−xSnxO2 is more compact and less flexible than that of Ce–O. The Sn coordination remains symmetric with eight equivalent, shorter Sn–O bonds, while Ce–O coordination gradually splits into a range of eight non-equivalent bonds compensating for the difference in the ionic radii of Ce4+ and Sn4+. Thus, a long-range effect of Sn doping is hardly extended throughout the lattice in Ce1−xSnxO2. In contrast, for Ce1−xZrxO2 solid solutions, both Ce and Zr have similar local coordination creating similar rearrangement of the oxygen substructure and showing a linear lattice parameter decrease up to 50% Zr substitution. We suggest that the localized effect of Sn substitution due to its higher electronegativity may be responsible for the deviation from Vegard's law in Ce1−xSnxO2 solid solutions

Two New Cynodonts (Therapsida) from the Middle-Early Late Triassic of Brazil and Comments on South American Probainognathians

<div><p>We describe two new cynodonts from the early Late Triassic of southern Brazil. One taxon, <i>Bonacynodon schultzi</i> gen. et sp. nov., comes from the lower Carnian <i>Dinodontosaurus</i> AZ, being correlated with the faunal association at the upper half of the lower member of the Chañares Formation (Ischigualasto-Villa Unión Basin, Argentina). Phylogenetically, <i>Bonacynodon</i> is a closer relative to <i>Probainognathus jenseni</i> than to any other probainognathian, bearing conspicuous canines with a denticulate distal margin. The other new taxon is <i>Santacruzgnathus abdalai</i> gen. et sp. nov. from the Carnian <i>Santacruzodon</i> AZ. Although based exclusively on a partial lower jaw, it represents a probainognathian close to <i>Prozostrodon</i> from the <i>Hyperodapedon</i> AZ and to <i>Brasilodon</i>, <i>Brasilitherium</i> and <i>Botucaraitherium</i> from the <i>Riograndia</i> AZ. The two new cynodonts and the phylogenetic hypothesis presented herein indicate the degree to which our knowledge on probainognathian cynodonts is incomplete and also the relevance of the South American fossil record for understanding their evolutionary significance. The taxonomic diversity and abundance of probainognathians from Brazil and Argentina will form the basis of deep and complex studies to address the evolutionary transformations of cynodonts leading to mammals.</p></div