Role of ß3 subunit of the GABA type A receptor in triple negative breast cancer proliferation, migration, and cell cycle progression.

Triple negative breast cancer (TNBC) is known for its heterogeneous nature and aggressive onset. The unresponsiveness to hormone therapies and immunotherapy and the toxicity of chemotherapeutics account for the limited treatment options for TNBC. Ion channels have emerged as possible therapeutic candidates for cancer therapy, but little is known about how ligand gated ion channels, specifically, GABA type A ligand-gated ion channel receptors (GABAAR), affect cancer pathogenesis. Our results show that the GABAA ß3 subunit is expressed at higher levels in TNBC cell lines than non-tumorigenic cells, therefore contributing to the idea that limiting the GABAAR via knockdown of the GABAA ß3 subunit is a potential strategy for decreasing the proliferation and migration of TNBC cells. We employed pharmacological and genetic approaches to investigate the role of the GABAA ß3 subunit in TNBC proliferation, migration, and cell cycle progression. The results suggest that pharmacological antagonism or genetic knockdown of GABAA ß3 subunit decreases TNBC proliferation and migration. In addition, GABAA ß3 subunit knockdown causes cell cycle arrest in TNBC cell lines via decreased cyclin D1 and increased p21 expression. Our findings suggest that membrane bound GABAA receptors containing the ß3 subunit can be further developed as a potential novel target for the treatment of TNBC.

Adult Organophosphate and Carbamate Insecticide Exposure and Sperm Concentration: A Systematic Review and Meta-Analysis of the Epidemiological Evidence.

BACKGROUND: Evidence of the negative impacts of contemporary use insecticides on sperm concentration has increased over the last few decades; however, meta-analyses on this topic are rare. OBJECTIVES: This investigation assessed the qualitative and quantitative strength of epidemiological evidence regarding adult exposure to two classes of contemporary use insecticides-organophosphates (OPs) and N-methyl carbamates (NMCs)-and sperm concentration using robust and reproducible systematic review and meta-analysis methods. METHODS: Three scientific databases (PubMed, Scopus, and Web of Science), two U.S. government databases (NIOSHTIC-2 and Science.gov), and five nongovernmental organization websites were searched for relevant primary epidemiological studies published in any language through 11 August 2022. Risk of bias and strength of evidence were evaluated according to Navigation Guide systematic review methodology. Bias-adjusted standardized mean difference effect sizes were calculated and pooled using a three-level, multivariate random-effect meta-analysis model with cluster-robust variance estimation. RESULTS: Across 20 studies, 21 study populations, 42 effect sizes, and 1,774 adult men, the pooled bias-adjusted standardized mean difference in sperm concentration between adult men more- and less-exposed to OP and NMC insecticides was -0.30 (95% CI: -0.49, -0.10; PSatt<0.01). Sensitivity and subgroup analyses explored statistical heterogeneity and validated the model robustness. Although the pooled effect estimate was modified by risk of bias, insecticide class, exposure setting, and recruitment setting, it remained negative in direction across all meta-analyses. The body of evidence was rated to be of moderate quality, with sufficient evidence of an association between higher adult OP and NMC insecticide exposure and lower sperm concentration. DISCUSSION: This comprehensive investigation found sufficient evidence of an association between higher OP and NMC insecticide exposure and lower sperm concentration in adults. Although additional cohort studies can be beneficial to fill data gaps, the strength of evidence warrants reducing exposure to OP and NMC insecticides now to prevent continued male reproductive harm. https://doi.org/10.1289/EHP12678.

The association between lead exposure and crime: A systematic review.

Prior research has demonstrated an association between lead exposure and criminal behavior at the population-level, however studies exploring the effect of lead exposure on criminal behavior at the individual-level have not been reviewed systematically. The intent of this study is to complete a systematic review of all studies assessing individual-level exposures to lead and the outcomes of crime and antisocial behavior traits. We included peer reviewed studies that were published prior to August 2022 and were classified as cohort, cross-sectional, or case-control. Studies measuring the outcomes of crime, delinquency, violence, or aggression were included. The following databases were searched using a standardized search strategy: ProQuest Environmental Science Database, PubMed, ToxNet and the Public Affairs Information Service (PAIS). Seventeen manuscripts met our inclusion criteria. Blood lead was measured in 12 studies, bone lead in 3 studies, and dentine lead levels in 2 studies. This systematic review identified a wide range of diverse outcomes between exposure to lead at multiple windows of development and later delinquent, criminal and antisocial behavior. A review of all potential confounding variables included within each study was made, with inclusion of relevant confounders into the risk of bias tool. There is limited data at the individual level on the effects of prenatal, childhood, and adolescent lead exposure and later criminal behavior and more evidence is necessary to evaluate the magnitude of the associations seen in this review. Our review, in conjunction with the available biological evidence, suggests that an excess risk for criminal behavior in adulthood exists when an individual is exposed to lead in utero or in the early years of childhood. The authors report no conflict of interest and no funding source. Clinical trial registration: PROSPERO ID: CRD42021268379.

Association between increasing agricultural use of 2,4-D and population biomarkers of exposure: findings from the National Health and Nutrition Examination Survey, 2001-2014.

BACKGROUND: 2,4-Dichlorophenoxyacetic acid (2,4-D) is one of the most extensively used herbicides in the United States. In 2012, 2,4-D was the most widely used herbicide in non-agricultural settings and the fifth most heavily applied pesticide in the US agricultural sector. The objective of this study was to examine trends in 2,4-D urinary biomarker concentrations to determine whether increases in 2,4-D application in agriculture are associated with increases in biomonitoring levels of urine 2,4-D. METHODS: Data from the National Health and Nutrition Examination Survey (NHANES) with available urine 2,4-D biomarker measurements from survey cycles between 2001 and 2014 were utilized. Urine 2,4-D values were dichotomized using the highest limit of detection (LOD) across all cycles (0.40 µg/L or 0.4 ppb). Agricultural use of 2,4-D was estimated by compiling publicly available federal and private pesticide application data. Logistic regression models adjusted for confounders were fitted to evaluate the association between agricultural use of 2,4-D and urine 2,4-D level above the dichotomization threshold. RESULTS: Of the 14,395 participants included in the study, 4681 (32.5%) had urine 2,4-D levels above the dichotomization threshold. The frequency of participants with high 2,4-D levels increased significantly (p < .0001), from a low of 17.1% in 2001-2002 to a high of 39.6% in 2011-2012. The adjusted odds of high urinary 2,4-D concentrations associated with 2,4-D agricultural use (per ten million pounds applied) was 2.268 (95% CI: 1.709, 3.009). Children ages 6-11 years (n = 2288) had 2.1 times higher odds of having high 2,4-D urinary concentrations compared to participants aged 20-59 years. Women of childbearing age (age 20-44 years) (n = 2172) had 1.85 times higher odds than men of the same age. CONCLUSIONS: Agricultural use of 2,4-D has increased substantially from a low point in 2002 and it is predicted to increase further in the coming decade. Because increasing use is likely to increase population level exposures, the associations seen here between 2,4-D crop application and biomonitoring levels require focused biomonitoring and epidemiological evaluation to determine the extent to which rising use and exposures cause adverse health outcomes among vulnerable populations (particularly children and women of childbearing age) and highly exposed individuals (farmers, other herbicide applicators, and their families).

An in vitro model of tumor heterogeneity resolves genetic, epigenetic, and stochastic sources of cell state variability.

Tumor heterogeneity is a primary cause of treatment failure and acquired resistance in cancer patients. Even in cancers driven by a single mutated oncogene, variability in response to targeted therapies is well known. The existence of additional genomic alterations among tumor cells can only partially explain this variability. As such, nongenetic factors are increasingly seen as critical contributors to tumor relapse and acquired resistance in cancer. Here, we show that both genetic and nongenetic factors contribute to targeted drug response variability in an experimental model of tumor heterogeneity. We observe significant variability to epidermal growth factor receptor (EGFR) inhibition among and within multiple versions and clonal sublines of PC9, a commonly used EGFR mutant nonsmall cell lung cancer (NSCLC) cell line. We resolve genetic, epigenetic, and stochastic components of this variability using a theoretical framework in which distinct genetic states give rise to multiple epigenetic "basins of attraction," across which cells can transition driven by stochastic noise. Using mutational impact analysis, single-cell differential gene expression, and correlations among Gene Ontology (GO) terms to connect genomics to transcriptomics, we establish a baseline for genetic differences driving drug response variability among PC9 cell line versions. Applying the same approach to clonal sublines, we conclude that drug response variability in all but one of the sublines is due to epigenetic differences; in the other, it is due to genetic alterations. Finally, using a clonal drug response assay together with stochastic simulations, we attribute subclonal drug response variability within sublines to stochastic cell fate decisions and confirm that one subline likely contains genetic resistance mutations that emerged in the absence of drug treatment.

Motorcycle safety after-dark: The factors associated with greater risk of road-traffic collisions.

The effect of ambient light level on road traffic collisions (RTCs) involving a motorcycle was investigated. Data were drawn from the STATS19 database of UK reported RTCs for the period 2005-2015. To isolate the effect of ambient light (daylight vs darkness) an odds ratio was used to compare RTCs at specific times of day in the weeks either side of the Spring and Autumn clock changes. This work extended previous studies by using a more precise method for distinguishing between RTCs in daylight and after dark, thus avoiding the ambiguity of twilight. Data for four-wheel motor vehicle (FWMV) RTCs were also investigated to provide a datum. As expected, the risk of an RTC occurring was significantly higher after dark compared to daylight for both motorcycles and FWMVs. Investigation of contextual factors suggests that risk after dark is significantly higher for motorcycles compared to FWMVs for RTCs with two-vehicles, on roads with low speed limits (≤30 mph), at T-junctions, and junctions controlled by a give way sign. These are the situations where visual aids for increasing conspicuity after dark have the greater potential for reducing motorcycle RTCs.

Author Correction: Proteomic and Transcriptomic Changes in Hibernating Grizzly Bears Reveal Metabolic and Signaling Pathways that Protect against Muscle Atrophy.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Proteomic and Transcriptomic Changes in Hibernating Grizzly Bears Reveal Metabolic and Signaling Pathways that Protect against Muscle Atrophy.

Muscle atrophy is a physiological response to disuse and malnutrition, but hibernating bears are largely resistant to this phenomenon. Unlike other mammals, they efficiently reabsorb amino acids from urine, periodically activate muscle contraction, and their adipocytes differentially responds to insulin. The contribution of myocytes to the reduced atrophy remains largely unknown. Here we show how metabolism and atrophy signaling are regulated in skeletal muscle of hibernating grizzly bear. Metabolic modeling of proteomic changes suggests an autonomous increase of non-essential amino acids (NEAA) in muscle and treatment of differentiated myoblasts with NEAA is sufficient to induce hypertrophy. Our comparison of gene expression in hibernation versus muscle atrophy identified several genes differentially regulated during hibernation, including Pdk4 and Serpinf1. Their trophic effects extend to myoblasts from non-hibernating species (including C. elegans), as documented by a knockdown approach. Together, these changes reflect evolutionary favored adaptations that, once translated to the clinics, could help improve atrophy treatment.

Age of first exposure to American football and long-term neuropsychiatric and cognitive outcomes.

Previous research suggests that age of first exposure (AFE) to football before age 12 may have long-term clinical implications; however, this relationship has only been examined in small samples of former professional football players. We examined the association between AFE to football and behavior, mood and cognition in a large cohort of former amateur and professional football players. The sample included 214 former football players without other contact sport history. Participants completed the Brief Test of Adult Cognition by Telephone (BTACT), and self-reported measures of executive function and behavioral regulation (Behavior Rating Inventory of Executive Function-Adult Version Metacognition Index (MI), Behavioral Regulation Index (BRI)), depression (Center for Epidemiologic Studies Depression Scale (CES-D)) and apathy (Apathy Evaluation Scale (AES)). Outcomes were continuous and dichotomized as clinically impaired. AFE was dichotomized into <12 and ⩾12, and examined continuously. Multivariate mixed-effect regressions controlling for age, education and duration of play showed AFE to football before age 12 corresponded with >2 × increased odds for clinically impaired scores on all measures but BTACT: (odds ratio (OR), 95% confidence interval (CI): BRI, 2.16,1.19-3.91; MI, 2.10,1.17-3.76; CES-D, 3.08,1.65-5.76; AES, 2.39,1.32-4.32). Younger AFE predicted increased odds for clinical impairment on the AES (OR, 95% CI: 0.86, 0.76-0.97) and CES-D (OR, 95% CI: 0.85, 0.74-0.97). There was no interaction between AFE and highest level of play. Younger AFE to football, before age 12 in particular, was associated with increased odds for impairment in self-reported neuropsychiatric and executive function in 214 former American football players. Longitudinal studies will inform youth football policy and safety decisions.

Life in the fat lane: seasonal regulation of insulin sensitivity, food intake, and adipose biology in brown bears.

Grizzly bears (Ursus arctos horribilis) have evolved remarkable metabolic adaptations including enormous fat accumulation during the active season followed by fasting during hibernation. However, these fluctuations in body mass do not cause the same harmful effects associated with obesity in humans. To better understand these seasonal transitions, we performed insulin and glucose tolerance tests in captive grizzly bears, characterized the annual profiles of circulating adipokines, and tested the anorectic effects of centrally administered leptin at different times of the year. We also used bear gluteal adipocyte cultures to test insulin and beta-adrenergic sensitivity in vitro. Bears were insulin resistant during hibernation but were sensitive during the spring and fall active periods. Hibernating bears remained euglycemic, possibly due to hyperinsulinemia and hyperglucagonemia. Adipokine concentrations were relatively low throughout the active season but peaked in mid-October prior to hibernation when fat content was greatest. Serum glycerol was highest during hibernation, indicating ongoing lipolysis. Centrally administered leptin reduced food intake in October, but not in August, revealing seasonal variation in the brain's sensitivity to its anorectic effects. This was supported by strong phosphorylated signal transducer and activator of transcription 3 labeling within the hypothalamus of hibernating bears; labeling virtually disappeared in active bears. Adipocytes collected during hibernation were insulin resistant when cultured with hibernation serum but became sensitive when cultured with active season serum. Heat treatment of active serum blocked much of this action. Clarifying the cellular mechanisms responsible for the physiology of hibernating bears may inform new treatments for metabolic disorders.

Isotopic Incorporation and the Effects of Fasting and Dietary Lipid Content on Isotopic Discrimination in Large Carnivorous Mammals.

There has been considerable emphasis on understanding isotopic discrimination for diet estimation in omnivores. However, discrimination may differ for carnivores, particularly species that consume lipid-rich diets. Here, we examined the potential implications of several factors when using stable isotopes to estimate the diets of bears, which can consume lipid-rich diets and, alternatively, fast for weeks to months. We conducted feeding trials with captive brown bears (Ursus arctos) and polar bears (Ursus maritimus). As dietary lipid content increased to ∼90%, we observed increasing differences between blood plasma and diets that had not been lipid extracted (∆(13)Ctissue-bulk diet) and slightly decreasing differences between plasma δ(13)C and lipid-extracted diet. Plasma Δ(15)Ntissue-bulk diet increased with increasing protein content for the four polar bears in this study and data for other mammals from previous studies that were fed purely carnivorous diets. Four adult and four yearling brown bears that fasted 120 d had plasma δ(15)N values that changed by <±2‰. Fasting bears exhibited no trend in plasma δ(13)C. Isotopic incorporation in red blood cells and whole blood was ≥6 mo in subadult and adult bears, which is considerably longer than previously measured in younger and smaller black bears (Ursus americanus). Our results suggest that short-term fasting in carnivores has minimal effects on δ(13)C and δ(15)N discrimination between predators and their prey but that dietary lipid content is an important factor directly affecting δ(13)C discrimination and indirectly affecting δ(15)N discrimination via the inverse relationship with dietary protein content.

A protocol for the isolation and cultivation of brown bear (Ursus arctos) adipocytes.

Brown bears (Ursus arctos) exhibit hyperphagia each fall and can become obese in preparation for hibernation. They do this without displaying the physiological problems typically seen in obese humans, such as Type 2 diabetes and heart disease. The study of brown bear hibernation biology could therefore aid in the development of novel methods for combating metabolic diseases. To this end, we isolated mesenchymal stem cells from subcutaneous fat biopsies, and culture methods were developed to differentiate these into the adipogenic lineage. Biopsies were taken from 8 captive male (N = 6) and female (N = 2) brown bears, ages 2-12 years. Plastic adherent, fibroblast-like cells were proliferated and subsequently cryopreserved or differentiated. Differentiation conditions were optimized with respect to fetal bovine serum content and time spent in differentiation medium. Cultures were characterized through immunostaining, RT-qPCR, and Oil red O staining to quantify lipid accumulation. Adiponectin, leptin, and glycerol medium concentrations were also determined over the course of differentiation. The culturing protocol succeeded in generating hormone-sensitive lipase-expressing, lipid-producing white-type adipocytes (UCP1 negative). Serum concentration and time of exposure to differentiation medium were both positively related to lipid production. Cells cultured to low passage numbers retained similar lipid production and expression of lipid markers PLIN2 and FABP4. Ultimately, the protocols described here may be useful to biologists in the field investigating the health of wild bear populations and could potentially increase our understanding of metabolic disorders in humans.

Induction of Dectin-1 and asthma-associated signal transduction pathways in RAW 264.7 cells by a triple-helical (1, 3)-ß-D glucan, curdlan.

People living in damp buildings are typically exposed to spore and mycelial fragments of the fungi that grow on damp building materials. There is experimental evidence that this exposure to triple-helical (1, 3)-ß-D glucan and low molecular weight toxins may be associated with non-atopic asthma observed in damp and moldy buildings. However, the mechanisms underlying this response are only partially resolved. Using the pure (1, 3)-ß-D glucan, curdlan, and the murine macrophage cell line, RAW 264.7, there were two objectives of this study. The first was to determine whether signal transduction pathways activating asthma-associated cell signaling pathways were stimulated using mouse transduction Pathway Finder(®) arrays and quantitative real-time (QRT) PCR. The second objective was to evaluate the dose and temporal responses associated with transcriptional changes in asthma-associated cytokines, the signal transduction receptor gene Dectin-1, and various transcription factor genes related to the induction of asthma using customized RT-PCR-based arrays. Compared to controls, the 10(-7) M curdlan treatment induced significant changes in gene transcription predominately in the NFkB, TGF-ß, p53, JAK/STAT, P13/AKT, phospholipase C, and stress signaling pathways. The 10(-8) M curdlan treatment mainly induced NFkB and TGF-ß pathways. Compared to controls, curdlan exposures also induced significant dose- and time-dependent changes in the gene translations. We found that that curdlan as a non-allergenic potentiator modulates a network of transduction signaling pathways not only associated with TH-1, TH-2, and TH-3 cell responses including asthma potentiation, but a variety of other cell responses in RAW 264.7 cells. These results help provide mechanistic basis for some of the phenotypic changes associated with asthma that have been observed in in vitro, in vivo, and human studies and open up a hypothesis-building process that could explain the rise of non-atopic asthma associated with fungi.

Lipid infusion in the management of poisoning: a report of 6 canine cases.

Intravenous administration of lipid is a relatively new treatment in the management of toxicity from lipophilic compounds. It is used in human medicine in the treatment of toxicity from lipophilic local anaesthetics and cardiotoxic drugs and can result in dramatic improvement in clinical status. We present six cases of poisoning in dogs successfully treated with lipid infusion after ingestion of ivermectin (3), moxidectin (2) and baclofen (1). The dogs ranged in age from eight weeks to 14 years, and weighed 4-30 kg. Intravenous lipid therapy was started between six and eight hours and 22 hours after ingestion, and all the dogs responded well. In four dogs, there was clinical improvement within one hour; one had improved within two hours and the other within 4.5 hours of lipid administration. The only adverse effect of lipid infusion reported was mild swelling and pain after extravasation in one case which resolved with conservative management. All the dogs were discharged within 24-52 hours after exposure (7-46 hours after the start of lipid administration), and none developed any apparent sequelae.

What women want - quantifying the perception of hair amount: an analysis of hair diameter and density changes with age in caucasian women.

BACKGROUND: It has long been known that women lose satisfaction with their hair with ageing. Our data show that caucasian women perceive a decrease in hair amount in their mid 40s with a further decrease in the mid to late 50s, which leads to this dissatisfaction. Neither loss of density (hairs per cm(2) ) nor shaft diameter alone can fully account for this perception. A new metric, 'hair amount', is proposed as a quantitative metric combining the impact of both density and diameter on the perception of hair loss. OBJECTIVES: Creation of a single parameter combining the contribution of diameter and density to perception of female age-related hair loss. METHODS: In total, 1099 caucasian women (ages 18-66 years) with self-perceived hair loss and 315 caucasian women (ages 17-86 years) with no complaint of hair loss were evaluated. Scalp hair diameter was measured using optical fibre diameter and image analysis. Scalp hair density was measured by phototrichogram with manual or automated counting. RESULTS: Parietal scalp hair diameter increased from ages 20 to 40-45 years, then decreased. Hair density was highest in the youngest group, age 20-30 years, and decreased thereafter with increasing rate. In women self-perceiving hair loss, the rate of decrease in density was significantly faster than for women with no self-perception of hair loss. The combined metric 'hair amount' was relatively constant at younger ages, increasing very slightly to age 35 years, then decreasing significantly. CONCLUSIONS: Increasing hair shaft diameter offsets decreasing hair density through the mid 30s. After that, a lower rate of diameter increase combined with the decrease in density begins to significantly impact the perception of hair amount so that thinning becomes increasingly more noticeable in the mid 40s to the mid to late 50s. Quantitative determination of hair amount is a useful tool to combine the contributions of hair density and diameter to women's perception of age-related hair loss.

Effects of low molecular weight fungal compounds on inflammatory gene transcription and expression in mouse alveolar macrophages.

The inflammatory potential and molecular mechanisms underscoring inflammatory responses of lung cells to compounds from fungi that grow on damp building materials is poorly understood in vitro. In this study we evaluated the effect of pure fungal compounds on potentiating acute inflammatory response in primary mouse alveolar macrophages (AMs) and tested the hypothesis that AM responses to low molecular weight fungal compounds exhibit temporal and compound specificity that mimic that observed in the whole lung. Transcriptional responses of 13 inflammation/respiratory burst-associated genes (KC=Cxcl1, Cxcl2, Cxcl5, Cxcl10, Ccl3, Ccl112, Ccl20, IL-1ß, Il-6, ifi27 Tnfα, iNOS and Blvrb) were evaluated in mouse AMs exposed to a 1ml (10(-8)mol) dose of either pure atranone C, brevianimide, cladosporin, curdlan, LPS, neoechinulin A & B, sterigmatocystin or TMC-120A for 2h, 4h and 12h PE using customized reverse transcription (RT)-PCR based arrays. Multianalyte ELISA was used to measure expression of 6 pro-inflammatory cytokines common to the transcriptional assays (Cxcl1, Cxcl10, Ccl3, IL1ß, Ifn-λ and Tnf-α) to determine whether gene expression corresponded to the transcription data. Compared to controls, all of these compounds induced significant (≥2.5-fold or ≤-2.5-fold change at p≤0.05) time- and compound-specific transcriptional gene alterations in treatment AMs. The highest number of transcribed genes were in LPS treatment AMs at 12h PE (12/13) followed by neoechinulin B at 4h PE (11/13). Highest fold change values (>30) were associated with KC, Cxcl2, Cxcl5 and IL1ß genes in cells exposed to LPS. Compound exposures also induced significant (p≤0.05) time- and compound-specific pro-inflammatory responses manifest as differentially elevated Cxcl1, Cxcl10, Ccl3, Ifn-λ and Tnf-α concentrations in culture supernatant of treatment AMs. Dissimilarity in transcriptional responses in AMs and our in vivo model of lung disease is likely attributable to whole lung vs. isolated cell responsive and dose differences between the two studies. The results not only indicate that low molecular weight compounds from fungi that grow in damp built environments are potently pro-inflammatory in vitro, it further highlights the important role AMs play in innate lung defence, and against exposure to low molecular weight fungal compounds. These observations further support our position that exposure to low molecular weight compounds from indoor-associated fungi may provoke some of the inflammatory health effects reported from humans in damp building environments. They also open up a hypothesis building process that could explain the rise of non-atopic asthma associated with fungi.

Hair breakage by combing and brushing--a comment on: T. A. Evans and K. Park, A statistical analysis of hair breakage. II. Repeated grooming experiments, J. Cosmet. Sci., 41, 439-456 (2010).

Literature dealing with the mechanisms of hair breakage in combing and brushing published so far has been reviewed as a background for the critical evaluation of the method and data analysis of the paper "Statistical Analysis of Hair Breakage. II" by Evans and Park (1). Accumulated knowledge about hair breakage in these grooming processes indicates that hair breakage in combing and brushing results from tangling, looping, knotting, and impact loading. Fatiguing, though responsible for some weakening of the fiber in the grooming process, it is unlikely to be a significant factor in hair breakage in combing and brushing.

Increased cardiac alpha-myosin heavy chain in left atria and decreased myocardial insulin-like growth factor (Igf-I) expression accompany low heart rate in hibernating grizzly bears.

Grizzly bears (Ursus arctos horribilis) tolerate extended periods of extremely low heart rate during hibernation without developing congestive heart failure or cardiac chamber dilation. Left ventricular atrophy and decreased left ventricular compliance have been reported in this species during hibernation. We evaluated the myocardial response to significantly reduced heart rate during hibernation by measuring relative myosin heavy-chain (MyHC) isoform expression and expression of a set of genes important to muscle plasticity and mass regulation in the left atria and left ventricles of active and hibernating bears. We supplemented these data with measurements of systolic and diastolic function via echocardiography in unanesthetized grizzly bears. Atrial strain imaging revealed decreased atrial contractility, decreased expansion/reservoir function (increased atrial stiffness), and decreased passive-filling function (increased ventricular stiffness) in hibernating bears. Relative MyHC-α protein expression increased significantly in the atrium during hibernation. The left ventricle expressed 100% MyHC-ß protein in both groups. Insulin-like growth factor (IGF-I) mRNA expression was reduced by ∼50% in both chambers during hibernation, consistent with the ventricular atrophy observed in these bears. Interestingly, mRNA expression of the atrophy-related ubiquitin ligases Muscle Atrophy F-box (MAFBx) and Muscle Ring Finger 1 did not increase, nor did expression of myostatin or hypoxia-inducible factor 1α (HIF-1α). We report atrium-specific decreases of 40% and 50%, respectively, in MAFBx and creatine kinase mRNA expression during hibernation. Decreased creatine kinase expression is consistent with lowered energy requirements and could relate to reduced atrial emptying function during hibernation. Taken together with our hemodynamic assessment, these data suggest a potential downregulation of atrial chamber function during hibernation to prevent fatigue and dilation due to excessive work against an optimally filled ventricle, a response unpredicted by the Frank-Starling mechanism.

Multicity HIV seroprevalence in street youth, Ukraine.

We conducted the first systematic, community-based, multicity assessment outside the USA of HIV seroprevalence, risk factors and linkage into clinical services among 929 street youth. After city-wide mapping, we used time-location sampling and randomly selected 74 venues in Odesa, Kyiv and Donetsk, Ukraine. Rapid HIV testing with post-test counselling was offered to all eligible youths aged 15-24 years. Overall, 18.4% (95% confidence interval 16.2-20.2) were HIV positive and 85% had previously unknown status. Rates were identical by sex. Subgroups with highest rates included orphans (26%), youths with histories of exchanging sex (35%), sexually transmitted infections (STIs) (37%), injection drug use (IDU) (42%) and needle sharing (49%). Independent predictors, similar across age groups and city, included being orphaned, time on the street, history of anal sex, STIs, exchanging sex, any drug use, IDU and needle sharing. Two-thirds (68%) of HIV-positive youths were linked to services. This high-risk population has many immediate needs.