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At least 415 records · Page 23Linked to original sources
PubMed1999

Cyclic expression of endothelin-converting enzyme-1 mediates the functional regulation of seminiferous tubule contraction.

The potent smooth muscle agonist endothelin-1 (ET-1) is involved in the local control of seminiferous tubule contractility, which results in the forward propulsion of tubular fluid and spermatozoa, through its action on peritubular myoid cells. ET-1, known to be produced in the seminiferous epithelium by Sertoli cells, is derived from the inactive intermediate big endothelin-1 (big ET-1) through a specific cleavage operated by the endothelin-converting enzyme (ECE), a membrane-bound metalloprotease with ectoenzymatic activity. The data presented suggest that the timing of seminiferous tubule contractility is controlled locally by the cyclic interplay between different cell types. We have studied the expression of ECE by Sertoli cells and used myoid cell cultures and seminiferous tubule explants to monitor the biological activity of the enzymatic reaction product. Northern blot analysis showed that ECE-1 (and not ECE-2) is specifically expressed in Sertoli cells; competitive enzyme immunoassay of ET production showed that Sertoli cell monolayers are capable of cleaving big ET-1, an activity inhibited by the ECE inhibitor phosphoramidon. Microfluorimetric analysis of intracellular calcium mobilization in single cells showed that myoid cells do not respond to big endothelin, nor to Sertoli cell plain medium, but to the medium conditioned by Sertoli cells in the presence of big ET-1, resulting in cell contraction and desensitization to further ET-1 stimulation; in situ hybridization analysis shows regional differences in ECE expression, suggesting that pulsatile production of endothelin by Sertoli cells (at specific "stages" of the seminiferous epithelium) may regulate the cyclicity of tubular contraction; when viewed in a scanning electron microscope, segments of seminiferous tubules containing the specific stages characterized by high expression of ECE were observed to contract in response to big ET-1, whereas stages with low ECE expression remained virtually unaffected. These data indicate that endothelin-mediated spatiotemporal control of rhythmic tubular contractility might be operated by Sertoli cells through the cyclic expression of ECE-1, which is, in turn, dependent upon the timing of spermatogenesis.

Animals↗
PubMed1996

Spontaneous mutants recovered from liver and germ cell tissue of low copy number lacI transgenic rats.

The finding of a large discordance between animal species in their response to a carcinogenic challenge, has led to the realization that the useful extrapolation of animal test data to humans requires a better understanding of animal interspecies differences. With the development of transgenic shuttle vector based animal systems we are now able to study mutation of the same genetic target in both mice and rats. We have begun to analyze mutants recovered from rat lines carrying low copy numbers of the same lambda/lacI constructs carried by the Big Blue mouse. A large database on mutations in lacI transgenic mice is already available for comparison. The data indicate that the differences between the mutations recovered from rat liver and germ cell tissues are similar to those recovered from transgenic mice, but when compared with a large database of mutations available for mice, some site-to-site differences may exist. This study represents the first interspecies look into the molecular nature of mutations in the lacI transgenic rodents.

Animals↗
PubMed2004

Injury patterns in big ten conference football.

BACKGROUND: In 1998, the National Collegiate Athletic Association legislated a decrease in the number of scrimmages and full-contact practices allowed during the spring season. HYPOTHESIS: A significantly increased risk of injury faced by the same player during the spring versus fall practice sessions does exist, but the National Collegiate Athletic Association regulations will not have the intended effect of reducing injury rates to equal or below those of the fall practice sessions. STUDY DESIGN: Retrospectively analyzed, descriptive study of prospectively collected injury surveillance data followed by a prospective, controlled, repeated-measures study after the rule change. METHODS: Phase 1: the Big Ten Conference Sports Injury Surveillance System database was reviewed from spring 1992 through fall 1997 for all reportable injuries. Phase 2: a prospective investigation was instituted from spring 1998 through fall 2000. This protocol was modified to also document updated individual player position descriptions and string as well as exposures for the old fall and spring practice categories (scrimmages, full contact, and limited contact) and the new spring practice designations (full pads with and without tackling, helmets only, spring game, and other scrimmages). RESULTS: Phase 1: There were 3950 fall injuries and 1007 spring injuries, with 469 of the 1007 attributable to the "spring risk factor." There was a statistically significant increase in injury rate in the spring (19.8) versus fall (10.6). Scrimmages (incidence density ratio = 2.4) and limited-contact practices (incidence density ratio = 2.5) showed more than twice the fall injury rate. Phase 2: There were 1502 fall injuries and 648 spring injuries, with 192 attributable to the spring risk factor. There was a 3-fold increase in injury rate in the spring (incidence density ratio = 3.2). Although the noncontact, helmets-only practices produced the lowest injury rates, the nonspring game scrimmages and the limited-contact practices defined as "practice with pads but without tackling" displayed the highest injury rates. In both spring and fall, nonplayers exhibited the highest injury rates for all string groups. CONCLUSIONS: There was and still is a statistically significant increase in spring practice injury risk. The 1998 rule change resulted in an even greater increase in spring practice injury risk. If the goal is to minimize the number of spring practice injuries, it will be best accomplished by limiting the number of scrimmages and limited-contact sessions.

Adult↗
PubMed1980

Rat lens epithelial cells in vitro. I. Observations on aging, differentiation and culture alterations.

Lens epithelial cells from rats aged 5 days were grown in long-term cultures. These cells age, differentiate and transform spontaneously. Morphological observations indicate five different stages (A-E). The epithelial character is lost after the first two passages. Elongated cells appearing afterwards are considered as cells that have started differentiation to fiberlike cells. Big flattened cells are considered as senescent cells that have lost theie proliferative capacity. Data from population kinetics also reflect these five stages. Chromosome analysis shows that three of the five stages are no longer diploid. Two alternative modes of spontaneous transformation are possible. The proliferative capacity of rat lens epithelial cells is higher than that of rat embryonic fibroblast systems.

Aging↗
PubMed2002

[Personality, accentuated traits and personality disorders. A contribution to dimensional diagnosis of personality disorders].

A dimensional diagnostic system for personality disorders (PD) postulates continuous transition from normal to disordered personalities (continuity hypothesis) and universal validity of basic personality dimensions (universal hypothesis). The present study investigates the validity of Leonhard's concept of attenuated personalities that define a conceptual link between normal personality dimensions and PD. Nine possible continuous transitions between three conceptual levels (Big Five personality factors, nine attenuated personality traits, nine PD) were tested by questionnaire data obtained from a mentally healthy (n = 166) and a clinical sample (n = 78). Both samples differed significantly in nearly all variables. However, they showed substantial similarity concerning the (in)validity of single continua and the complex structure of all variables as analyzed by multidimensional scaling. The concept of attenuated personalities could be validated for six out of nine tested continua and can be recommended for application in dimensional models of personality and personality disorders.

Adult↗
PubMed1994

Heterogeneity of human prolactin. Influence on immunoassays (RIA and IRMA).

Plasma hPRL consists of a complex mixture of molecular forms. The monomeric form, derived from the pituitary, is the main form. Others (dimeric or oligomeric) can form de novo in plasma. Recently, BBPRL (big big PRL) has been identified in some cases as an antiPRL autoantibody, but these data require further investigation. The PRL forms are differently recognized by immunoassays (IRMA and RIA) and are a source of inter-assay discrepancy.

Humans↗
PubMed2006

Recruitment issues when primary care population clusters are used in randomised controlled clinical trials: climbing mountains or pushing boulders uphill?

Cluster randomised controlled trials for health promotion, education, public health or organisational change interventions are becoming increasingly common to inform evidence-based policy. However, there is little published methodological evidence on recruitment strategies for primary care population clusters. In this paper, we discuss how choosing which population cluster to randomise can impact on the practicalities of recruitment in primary care. We describe strategies developed through our experiences of recruiting primary care organisations to participate in a national randomised controlled trial of a policy to provide community breastfeeding groups for pregnant and breastfeeding mothers, the BIG (Breastfeeding in Groups) trial. We propose an iterative qualitative approach to recruitment; collecting data generated through the recruitment process, identifying themes and using the constant comparative method of analysis. This can assist in developing successful recruitment strategies and contrasts with the standardised approach commonly used when recruiting individuals to participate in randomised controlled trials. Recruiting primary care population clusters to participate in trials is currently an uphill battle in Britain. It is a complex process, which can benefit from applying qualitative methods to inform trial design and recruitment strategy. Recruitment could be facilitated if health service managers were committed to supporting peer reviewed, funded and ethics committee approved research at national level.

Cluster Analysis↗
PubMed2004

Environmental genomics, the big picture?

The enormous sequencing capabilities of our times might be reaching the point of overflowing the possibilities to analyse data and allow for a feedback on where to focus the available resources. We have now a foreseeable future in which most bacterial species will have an annotated genome. However, we know also that most prokaryotic diversity would not be included there. On the one hand, there is the problem of many groups not being easily amenable to culture and hence not represented in culture-centred microbial taxonomy. On the other hand, the gene pools present in one species can be orders of magnitude larger than the genome of one strain (selected for genome sequencing). Contrasting with eukaryotic genomes, the repertoire of genes present in one prokaryotic cell genome does not correlate stringently with its taxonomic identity. Hence gene catalogues from one environment might provide more meaningful information than the classical species catalogues. Metagenomics or microbial environmental genomics provide a different tool that gravitates around the habitat rather than the species. Such a tool could be just the right way to complement "organismal genomics". Its potential to advance our understanding of microbial ecology and prokaryotic diversity and evolution is discussed.

Ecology↗
PubMed1992

Evidence against a pathogenetic role for endothelin in pre-eclampsia.

OBJECTIVE: To assess whether increased placental or systemic endothelin synthesis has a pathogenic role in pre-eclampsia (gestational proteinuric hypertension). DESIGN: Prospective observations study. SUBJECTS: 19 women with pre-eclampsia and 10 healthy pregnant women were studies. All were in the last trimester. MAIN OUTCOME MEASURES: Preproendothelin-1 gene expression by Northern blot analysis and generation of endothelin-1 precursor, big-endothelin-1, and endothelin isoforms, namely endothelin-1, 2 and 3, were assessed by specific radio-immunoassays, in placental tissue. Plasma endothelin-1 levels and urinary excretion of big-endothelin-1 and endothelin-1 were measured. RESULTS: Placental preproendothelin-1 gene expression and immunoreactive big-endothelin-1 and endothelin-1, 2 and 3, were comparable in placental tissue from pre-eclamptic and normal pregnant women. Plasma levels of endothelin-1 did not differ between pre-eclamptic and normal pregnancies. In contrast, urinary excretion of endothelin-1, which is likely to reflect the renal synthesis of the peptide, was significantly decreased in pre-eclamptic, as compared with normal pregnant women. This was not due to a decreased renal generation of endothelin-1 precursor, since urinary excretion of big-endothelin-1 did not differ between pre-eclamptic and normal pregnancies. These data suggest an increased renal endothelin-1 breakdown in pre-eclampsia. CONCLUSIONS: Endothelin is unlikely to play a role in the pathogenesis of pre-eclampsia. Instead, an increased renal breakdown may have a role in limiting the negative effects of other vasoactive factors on the renal circulation.

Adult↗
PubMed2004

The Fifth Nagoya International Blood And Marrow Transplantation Symposium: unlimited possibilities of hematopoietic cell transplantation: lessons from the past and prospects for the future.

In this symposium, a new concept, alloreactive NK cells regulated by KIR, was discussed extensively. There is no doubt that KIR epitope compatibility has a critical impact on the transplantation outcome; however, it is too early to determine the significance of KIR genotyping over KIR epitope assumption based on HLA type. We need to wait for a large-scale analysis to be done before we know the answer. What became clear in this meeting is that big collaborations or multicenter studies are becoming more important as sources of ethnic background data, and many other factors are found to affect clinical outcomes, making center-to-center comparisons more difficult.

Hematopoietic Stem Cell Transplantation↗
PubMed1995

CHIN building, step one: create a consensus.

The Big Three automakers long have wanted Michigan health care providers to give them outcomes data so the care companies could gauge the cost-effectiveness of the care their workers get in the Detroit area. At first, the car companies saw the fledgling Michigan Health Management Information System as the way to finally get the data they've wanted. Eventually, though, after long discussions with other network participants, the carmakers opted to scale back expectations, agreeing that the network should focus first on moving administrative transactions between health care purchasers, payers and providers.

Community Networks↗
PubMed2003

[Prevalence of atopic dermatitis in school children of Baranya county].

INTRODUCTION: The prevalence of atopic dermatitis (AD) in children has significantly increased worldwide in the past decades. Although it is well known that the number of AD patients has also been growing in Hungary no prevalence studies on a given population have been performed so far. METHODS: The present research investigated the prevalence of AD in school children by means of questionnaires. The data of 1454 (771 girls, 683 boys) children aged 6-14 years in a big city (Pécs, Hungary) and three small settlements (Bóly, Magyarbóly, Villány; Hungary) were analyzed. RESULTS: Applying the standard point values of the Schultz-Larsen questionnaire the prevalence of AD accounted for 15.1%; it was higher in the big city (16.5%) and lower in the small settlements (13.7%). In girls the prevalence of AD (15.9%) was greater than in boys (14%); this difference was more remarkable in the big city (18.2% vs. 14.8%). The first symptoms of AD appeared before the age of two in 58.8% and it was significantly higher in the big city (63.5%) as in the small settlements (52.6%). Among the 221 AD patients there were 38 patients (17.1%) with asthma and 93 (42.1%) with allergic rhinitis. The AD family (parents, brothers and sisters, great parents) proved to be positive in 72.8%. CONCLUSIONS: The results indicate the high prevalence rate of AD in school children in Baranya County, Hungary reaching or nearly approaching the significantly high values registered in the welfare countries.

Adolescent↗
PubMed1997

The position of AIDS in Pakistan, UAE and Jordan.

AIDS is a term used for Acquired Immuno-Deficiency Syndrome. It is, by definition, the end-stage disease manifestation of an infection with a virus called human immunodeficiency virus (HIV). The virus infects mainly two system of the body i.e. the immune system and central nervous system (CNS) and the occurrence of disease is due to the damage of these two systems. The statistics on AIDS are alarming, especially for Sub-Saharan Africa India. Some scientific studies indicated that upto one-third of all sexually active adults living in this region are already infected, up to 40% of all women and one in 10 to one in 5 children born in this part are actively infected with HIV and will be dead before having reached their fifth birthday. The information on HIV infected young adults were collected both from official and non-official sources of the following countries, Jordan, UAE, Pakistan. A big difference in number of patients was found between official and non-official data. Anyhow, both data (official & non-official) are alarming due to the increase in number of HIV cases. 21st century is especially dangerous to the next generation of Pakistan and Arab World because of increase in percentage of HIV cases during the last 5 years.

Journal Article↗
PubMed2000

5S ribosomal RNA.

Ribosomes have been visualized in electron micrographs in 1943 but 5S rRNA was discovered 20 years later. The next four decades witnessed big advances in our understanding of the ribosome using biochemical, genetic and low resolution structural approaches. During those times many experimental data accumulates also on 5S rRNA, but its precise function remains unknown. To understand the role of this RNA in ribosome a high-resolution structure is urgently needed. Because the ribosome is a dynamic machine, details on the interaction of 5S rRNA with proteins within entire ribosome are required. Big progress in the structural analysis of ribosome will stimulate further understanding of 5S rRNA.

Animals↗
PubMed2001

[The model of statoconia distribution in the gravity receptors of shells in ontogenesis].

Based on the experimental data of Wiederhold et al., analyzed was distribution of statoconia in gravireceptors of Biomphalaria glabrata and Aplysia californica in ontogenesis. A mathematical model of size distribution of statoconia in statocyst Biomphalaria glabrata in ontogenesis has been developed. Growth of statoconia in size is described as a process of crystallization from solution. Hypothetically, redistribution of statoconia in ontogenesis is determined by generation of new statoconia and their linear growth in size. Comparison of the resultant analytical solution of the model with published experimental data revealed a number of characteristic stages in statoconia development. Generation of new statoconia if peculiar for stage 1 and proceeds till the shell diameter (D) becomes as large as 4 mm. At D > 6 mm, statoconia distribution is driven by their size growth at a permanent rate. In the interval of delta D = 4-6 mm, statoconia undergo redistribution which is probably connected with selective dissolution of big statoconia and ensuing period of linear growth. The model is in good agreement with the literature on experimental data and, therefore, is instrumental in evaluation of changes in statoconia distribution. The authors laid out plans of further experiments in order to test the model of statoconia distribution in Biomphalaria glabrata in ontogenesis, and to get quantitative description of statoconia distribution in the gravireceptor of Aplysia californica in ontogenesis.

Animals↗
PubMed1992

Probing the big five in adolescence: personality and adjustment during a developmental transition.

The present study probed the links among Big Five personality differences, self-reported personality differences, and adjustment to school among young adolescents. We used a multimethod converging analysis, with three sources of data: (a) adolescent self-report on standardized personality inventories; (b) classroom teacher trait ratings and evaluations of adjustment; and (c) school guidance counselor evaluations of adjustment. Evaluations of adolescent adjustment were systematically related to Big Five personality differences, as assessed by both classroom teachers' and school counselors' ratings. For classroom teachers, adjustment was closely related to evaluations on the Big Five dimension of Conscientiousness. Adolescent self-report on several standardized measures was not related to adult evaluation of school adjustment. We suggest that the five-factor model may be a useful tool for probing adjustment during the transition to adolescence.

Achievement↗