Artificial barriers prevent genetic recovery of small isolated populations of a low-mobility freshwater fish.

Habitat loss and fragmentation often result in small, isolated populations vulnerable to environmental disturbance and loss of genetic diversity. Low genetic diversity can increase extinction risk of small populations by elevating inbreeding and inbreeding depression, and reducing adaptive potential. Due to their linear nature and extensive use by humans, freshwater ecosystems are especially vulnerable to habitat loss and fragmentation. Although the effects of fragmentation on genetic structure have been extensively studied in migratory fishes, they are less understood in low-mobility species. We estimated impacts of instream barriers on genetic structure and diversity of the low-mobility river blackfish (Gadopsis marmoratus) within five streams separated by weirs or dams constructed 45-120 years ago. We found evidence of small-scale (<13 km) genetic structure within reaches unimpeded by barriers, as expected for a fish with low mobility. Genetic diversity was lower above barriers in small streams only, regardless of barrier age. In particular, one isolated population showed evidence of a recent bottleneck and inbreeding. Differentiation above and below the barrier (FST = 0.13) was greatest in this stream, but in other streams did not differ from background levels. Spatially explicit simulations suggest that short-term barrier effects would not be detected with our data set unless effective population sizes were very small (<100). Our study highlights that, in structured populations, the ability to detect short-term genetic effects from barriers is reduced and requires more genetic markers compared to panmictic populations. We also demonstrate the importance of accounting for natural population genetic structure in fragmentation studies.

Fitness to drive in cognitive impairment--a quantitative study of GPs' experience.

Assessing fitness to drive is part of the role of general practitioners. Cognitive impairment may affect an individual's ability to drive safely. The aims of our study were to question GPs about their experience of assessing patients with cognitive impairment for driving fitness and to explore their attitudes to this role. We carried out a quantitative cross-sectional anonymous postal survey of 200 GPs in counties Galway, Mayo and Roscommon. Ethical approval was obtained from the Irish College of General Practitioners. Data was analysed using Epi Info. The response rate was 62.5% (n=125). 86 (68.8%) GPs used guidelines when assessing fitness to drive in cognitive impairment. 83 (66.4%) respondents formally assess cognitive function. 52 (41.6%) GPs would certify someone as fit to drive with verbal restrictions. 102 (81.6%) respondents feel confident in assessing fitness to drive. 98 (78.4%) GPs have referred patients for further assessment.

Queen quality, performance, and winter survival of imported and domestic honey bee queen stocks.

Canadian beekeepers have faced high colony mortality each winter over the last decade. Frequently citing "poor queen quality" as a top contributing factor to colony loss, Canadian beekeepers report needing to replace half their queens each year. Domestic queen production exists throughout Canada but is limited due to the short season and can be further limited when colony mortality is high. Consequently, Canadian beekeepers import over 260,000 queens annually, primarily from locations with warmer climates. In this study, newly mated imported queens from Hawaii (USA) and New Zealand were compared to domestic Canadian queens produced in British Columbia; these stocks were evaluated on their morphological and sperm storage characteristics. Stock quality was also evaluated in the field at two locations in Alberta, Canada over two production seasons. Our results show initial variation in queen morphology and fertility among imported and domestic queen stocks. Most striking, the New Zealand queens weighed 10-13% less than the Hawaii and British Columbia queens, respectively upon arrival. Colony performance over a two-year field study suggests: (1) brood pattern solidness has a positive nonlinear correlation with honey production regardless of queen stock and environment; (2) environment (i.e., apiary location) and queen stock variably predict colony health and productivity depending on year; specifically, apiary site appears to be a stronger predictor of colony health and productivity than queen stock in year one, but in year two, queen stock appears to be a stronger predictor than apiary site; (3) high clinical symptoms of chalkbrood may explain the prevalence of poor brood patterns in colonies headed by queens from New Zealand; (4) domestic queens are 25% more likely to survive winter in Alberta than imported queens. Therefore, it is important to consider possible mismatches in disease immunity and climate conditioning of imported queen stocks heading colonies in temperate regions that face drastically different seasonal climates and disease ecology dynamics.

Assessment of differences in HLA-A, -B, and -DRB1 allele mismatches among African-American and non-African-American recipients of deceased kidney transplants.

Among recipients of deceased donor kidney transplants, African-Americans experience a more rapid rate of kidney allograft loss than non-African-Americans. The purpose of this study was to characterize and quantify the HLA-A, -B, and -DRB1 allele mismatches and amino acid substitutions at antigen recognition sites among African-American and non-African-American recipients of deceased donor kidney transplants matched at the antigen level. In recipients with zero HLA antigen mismatches, the degree of one or two HLA allele mismatches for both racial groups combined was 47%, 29%, and 11% at HLA-DRB1, HLA-B, and HLA-A, respectively. There was a greater number of allele mismatches in African-Americans than non-African-Americans at HLA-A (P < .0001), -B (P = .096), and -DRB1 loci (P < .0001). For both racial groups, the HLA allele mismatches were predominantly at A2 for HLA-A; B35 and B44 for HLA-B; but multiple specificities for HLA-DRB1. The observed amino acid mismatches were concentrated at a few functional positions in the antigen binding site of HLA-A and -B and -DRB1 molecules. Future studies are ongoing to assess the impact of these HLA mismatches on kidney allograft loss.

Statistics of transmitter release at nerve terminals.

This review presents an historical account of the developments of the statistical analysis of quantal transmission over the past half century and of the progress made in using this approach to reveal new properties of nerve terminals. In the early 1950s, Katz and his colleagues showed that evoked transmitter release occurred in quanta at the neuromuscular junction, opening up the study of transmitter release at nerve terminals to statistical analysis. In the subsequent two decades attempts were made to see if evoked quantal release could be described by binomial or compound binomial statistics, as originally suggested by Katz, and to relate the parameters of the statistic to various structures of the nerve terminal. During this period two hypotheses were enunciated, namely the 'vesicle hypothesis', which states that quanta arise as a consequence of the packaging of transmitter in vesicles; and the 'active zone hypothesis', which states that vesicles undergo exocytosis at discrete sites on the nerve terminal. Unsuccessful attempts were made to relate the binomial parameter n to the elements in these hypotheses, that is to the number of active zones possessed by the terminal or the number of vesicles available for release at these zones. This difficulty was part resolved in the late 1970s with the application of non-uniform binomial statistics to transmitter release from nerve terminals, in which n is the number of active zones each with their individual probabilities, p(j). Autocorrelation functions were subsequently introduced to detect if transmitter release is quantised at a particular nerve terminal. Statistical methods which would allow discrimination between different models of transmitter release over the active zones of a terminal were then developed. The introduction of maximum likelihood estimation procedures then allowed estimates to be made of the parameters in the statistical models of quantal release. The application of these procedures to experimental data from a variety of nerve terminals provided evidence for the concept that each synapse, taken as possessing a single active zone, possesses its own individual probability of secretion of a quantum by the exocytosis of a vesicle. In the late 1960s Stevens introduced the first stochastic approach to the analysis of the kinetics of the release of a quantum of transmitter at the neuromuscular junction following an impulse. In the subsequent decades this was developed into an explicit theory for the interaction of proteins involved in regulated exocytosis of a vesicle at an active zone. The parameters were the number of transition steps in the release process (k), each occurring at the same rate (alpha), with the possibility of each of these steps becoming blocked at the same rate (gamma). Maximum likelihood estimation procedures could then be used to obtain these parameter values. The discovery was made in the 1990s of the core proteins of the SNARE complex that govern regulated exocytosis. This offers the possibility in the near future of identifying the kinetic interaction of these proteins with the parameters of the stochastic process of exocytosis which confer a particular probability on individual synapses.

Note: A portable laser induced breakdown spectroscopy instrument for rapid sampling and analysis of silicon-containing aerosols.

A portable instrument has been developed for measuring silicon-containing aerosols in near real-time using laser-induced breakdown spectroscopy (LIBS). The instrument uses a vacuum system to collect and deposit airborne particulate matter onto a translatable reel of filter tape. LIBS is used to analyze the deposited material, determining the amount of silicon-containing compounds present. In laboratory testing with pure silica (SiO2), the correlation between LIBS intensity for a characteristic silicon emission and the concentration of silica in a model aerosol was determined for a range of concentrations, demonstrating the instrument's plausibility for identifying hazardous levels of silicon-containing compounds.

Ninety-day perioperative complications of pediatric robotic urological surgery: A multi-institutional study.

BACKGROUND: Robotic technology is the newest tool in the armamentarium for minimally invasive surgery. Individual centers have reported on both the outcomes and complications associated with this technology, but the numbers in these studies remain small, and it has been difficult to extrapolate meaningful information. OBJECTIVES: The intention was to evaluate a large cohort of pediatric robotic patients through a multi-center database in order to determine the frequency and types of complications associated with robotic surgery for pediatric reconstructive and ablative procedures in the United States. STUDY DESIGN: After institutional review board approvals at the participating centers, data were retrospectively collected (2007-2011) by each institute and entered into a RedCap(®) database. Available demographic and complication data that were assigned Clavien grading scores were analyzed. RESULTS: From a cohort of 858 patients (880 RAL procedures), Grade IIIa and Grade IIIb complications were seen in 41 (4.8%); and one patient (0.1%) had a grade IVa complication. Intraoperative visceral injuries secondary to robotic instrument exchange and traction injury were seen in four (0.5%) patients, with subsequent conversion to an open procedure. Grade I and II complications were seen in 59 (6.9%) and 70 (8.2%) patients, respectively; they were all managed conservatively. A total of 14 (1.6%) were converted to an open or pure laparoscopic procedure, of which, 12 (86%) were secondary to mechanical challenges. DISCUSSION: It is believed that this study represents the largest and most comprehensive description of pediatric RAL urological complications to date. The results demonstrate a 4.7% rate of Clavien Grade IIIa and Grade IIIb complications in a total of 880 cases. While small numbers make it difficult to draw conclusions regarding the most complex reconstructive cases (bladder diverticulectomy, bladder neck revision, etc.), the data on the more commonly performed procedures, such as the RAL pyeloplasty and ureteral reimplantation, are robust and more likely represent the true complication rate for these procedures when performed by highly experienced robotic surgeons. CONCLUSION: Pediatric robotic urologic procedures are technically feasible and safe. The overall 90-day complication rate is similar to reports of laparoscopic and open surgical procedures. COMPLICATIONS: n (%) Life threatening (IVa): 1 (0.1%) Requiring radiologic and or surgical intervention (IIIa and IIIb): 41 (4.8%) Secondary to robotic system: 4 (0.5%) Mechanical failure leading to conversion: 14 (1.6%).

Detection of anti-HLA antibody by flow cytometry in patients with a left ventricular assist device is associated with early rejection following heart transplantation.

BACKGROUND: Patients with a left ventricular assist device (LVAD) as a bridge to heart transplantation (HT) often have elevated levels of panel reactive antibodies (PRA). The clinical significance of anti-human histocompatibility leukocyte antigen (HLA) antibodies detected by flow cytometry in PRA negative patients remains unclear. METHODS: Eighteen patients who underwent LVAD placement as a successful bridge to HT had standard anti-human globulin complement-dependent cytotoxicity and retrospective flow cytometry assays performed to detect class I anti-HLA antibodies. A positive flow result was defined as a fluorescent ratio of 23:1 versus a negative control. RESULTS: Six patients had anti-HLA antibodies detected by flow cytometry. Univariate analysis demonstrated more moderate-severe rejection episodes (ISHLT > or = IIIA) at 2 months (0.83+/-0.75 vs. 0; P=0.04) and a trend toward decreased time to first rejection (61+/-17 vs. 225+/-62 days; P=0.06) in these patients. No differences were observed in donor-recipient HLA mismatch or 1 year Kaplan-Meier survival between patients with or without anti-HLA antibodies. CONCLUSION: Despite a negative PRA, LVAD patients with class I anti-HLA antibodies detected by flow cytometry have a greater incidence of moderate-severe rejection in the first 2 months after HT. Flow cytometry may be a useful clinical tool in screening PRA negative LVAD patients before transplantation. Patients with positive anti-HLA antibody screening by flow cytometry may require more intensive immunosuppression in the early post-HT period.

Congenital hereditary (juvenile X-linked) retinoschisis. Histopathologic and ultrastructural findings in three eyes.

One surgically enucleated and two postmortem eyes were obtained from two related men with congenital hereditary retinoschisis. A periodic acid-Schiff-positive amorphous material was identified within the retina adjacent to the schisis cavities. Ultrastructural examination of this material showed numerous extracellular filaments, measuring approximately 11 nm in diameter. Similar filaments were found in the vitreous in all three globes and in a normal globe. We believe that the intraretinal filaments are produced by defective Müller cells and that their extracellular accumulation may lead to degeneration of cells and subsequent schisis formation.

Pre- and post-employment median nerve latency in pork processing employees.

There is some controversy regarding the relationship between development of median nerve dysfunction and employment activities. We performed nerve conduction studies of median nerve function on individuals before and after starting employment in the pork processing industry. After working an average of 64 days, employees (n = 45) showed significant prolongation of median motor and sensory nerve latency when comparing initial and final testing results in both dominant and non-dominant hands (P = < 0.01 to 0.03). A similar trend was found when testing a smaller group of employees (n = 17) who were already working (mean of 3 days), though this did not generally reach statistical significance. This study supports the conclusion that prolongation of median motor and sensory nerve latency can occur within as little as 2 months after beginning employment in the pork processing industry.

Peer networks among heavy, regular and infrequent drinkers prior to marriage.

OBJECTIVE: Research has consistently demonstrated that, among adolescents, the characteristics of one's peers are important predictors of substance abuse. The impact of the peer network on adult drinking, however, has received considerably less attention. The purpose of the present study was to examine social network characteristics that are associated with heavy drinking in adulthood prior to marriage. METHOD: Couples were recruited at the time of their first marriage. Husbands and wives were each given identical questionnaire packets to complete at home, independently, as well as a postage-paid envelope for packet return. A broad range of constructs was assessed; included were personality characteristics, relationship functioning, drinking behavior and social network characteristics. Complete data were obtained from 471 husbands and 471 wives. RESULTS: The social networks of heavy-drinking men, compared to men drinking regularly or infrequently, were younger, more likely to be male and unmarried and consisted of friends rather than family or others. For both men and women, "drinking buddies" accounted for nearly 75% of the heavy drinkers' peer networks. The overall ratings of support and conflict created by peers did not differ according to drinking group, for either men or women. CONCLUSIONS: Prior to marriage, the social networks of heavy drinkers differ considerably from the networks of regular or infrequent drinkers with regard to the drinking patterns of their peers. An important finding was that heavy drinkers appear to experience a similar level of emotional, financial and practical support from their peer network compared to regular or infrequent drinkers.

Preparing samples for the recording of infrared spectra from synthetic fibers.

An improved technique for recording infrared spectra from minute amounts of synthetic fibers by using KBr micropellets is described. The procedure is the same for all commonly encountered synthetic fiber varieties; hence, no preliminary identification is required.

2,4-D adsorption to biochars: effect of preparation conditions on equilibrium adsorption capacity and comparison with commercial activated carbon literature data.

Batch isotherm experiments were conducted with chars to study adsorption of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). Chars generated from corncobs, bamboo and wood chips in a laboratory pyrolyzer at 400-700 °C were compared with traditional kiln charcoals collected from villages in S/SE Asia and with activated carbons (ACs). 2,4-D uptake by laboratory chars obtained from bamboo and wood chips after 14 h of pyrolysis at 700 °C, from wood chips after 96 h of pyrolysis at 600 °C, and one of the field-collected chars (basudha) was comparable to ACs. H:C and O:C ratios declined with pyrolysis temperature and duration while surface area increased to >500 m(2)/g. Increasing pyrolysis intensity by increasing temperature and/or duration of heating was found to positively influence adsorption capacity yield (mg(2,4-D/g(feedstock))) over the range of conditions studied. Economic analysis showed that high temperature chars can be a cost-effective alternative to ACs for water treatment applications.

Paraneoplastic isolated myelopathy: clinical course and neuroimaging clues.

OBJECTIVE: To report the clinical phenotype and outcome of isolated paraneoplastic myelopathy. METHODS: We systematically reviewed clinical, serologic, and MRI data for 31 patients (20 female) who presented with an isolated myelopathy and coexisting cancer: carcinoma (lung, 9; breast, 7; kidney, 2; thyroid, 2; ovary/endometrium, 2), melanoma (2), or other cancer (3), or a paraneoplastic autoantibody with strong cancer association (amphiphysin-immunoglobulin G [IgG], 9; collapsin response-mediator protein 5-IgG, 9; Purkinje-cell cytoplasmic autoantibody type 1, 2; antineuronal nuclear autoantibody [ANNA]-1, 1; ANNA-3, 1). RESULTS: Of 31 patients who presented with a progressive myelopathy, symptom onset was subacute in 16 (52%). The median age was 62 years. CSF abnormalities included elevated protein (>45 mg/dL), 22; pleocytosis, 15; excess oligoclonal bands (normal <4), 7. MRI cord abnormalities identified in 20 patients were longitudinally extensive (>3 vertebral segments), 14; symmetric tract or gray matter-specific signal abnormality, 15 (enhancing in 13). Myelopathy preceded cancer diagnosis in 18 patients (median interval 12 months; range 2-44). After myelopathy onset, 26 patients underwent oncologic treatment, immunosuppressive treatment (median delay to commencing immunotherapy 9.5 months [range 1-54]), or both; only 8 improved (31%). At last neurologic evaluation (median interval after onset 17 months; range 1-165 months), 16 patients (52%) were wheelchair-dependent (median time from onset to wheelchair 9 months [range 1-21]). Ten patients died after a median of 38 months from symptom onset (range 7-152). CONCLUSION: Symmetric, longitudinally extensive tract or gray matter-specific changes on spinal MRI should raise suspicion for a paraneoplastic myelopathy. Resulting disability is often severe. Only a minority of patients improve with treatment.