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S Singleton

Publications and source records attributed to S Singleton.

15 recordsLinked to original sources
PubMed2006

Testis/sperm-specific histone 2B in the sperm of donors and subfertile patients: variability and relation to chromatin packaging.

BACKGROUND: The compaction of human sperm chromatin is the result of replacement of approximately 85% of histones with protamines. Germ-line testis/sperm-specific histone 2B (TSH2B) has been detected in only approximately 30% of mature spermatozoa. Its level in the semen of subfertile patients varies; its function is unknown. We evaluated TSH2B in the sperm samples of 23 donors and 49 subfertile patients and assessed its association with chromatin compaction status. METHODS: TSH2B level was measured using immunoblotting. Chromatin packaging quality was evaluated by staining with chromomycin A3 (CMA3) which marked spermatozoa with defective packaging. To assess both TSH2B and chromatin status in the same spermatozoon, CMA3 staining and TSH2B immunolocalization were performed sequentially. RESULTS: A significant correlation (r = 0.55, P = 0.0027) was found between TSH2B level and percentage of CMA3-positive sperm in patient and donor semen samples. When individual spermatozoa were assessed for these parameters, 92% of TSH2B-containing cells were also CMA3 positive. Variation in the total sperm TSH2B level was less in donors than in patients. CONCLUSIONS: CMA3 positive staining of TSH2B-containing individual spermatozoa and a significant correlation between the total TSH2B level and CMA3 percentage in semen samples suggest a structural role for TSH2B in sperm chromatin organization. Low variability of TSH2B level in donors implies a mechanism (however unknown) regulating this parameter.

Chromatin↗
PubMed2001

A fully automated microscope bacterial enumeration system for studies of oral microbial ecology.

A fast and fully automated image analysis technique for the enumeration of fluorescence-labeled bacteria in oral sampleswas developed. This paper describes the system configuration, application strategy, automated operation, and initial validation experiments using fluorescent microspheres, bacterial cultures, in vitro grown biofilms and human dental plaque. Following a series of brief operator-controlled calibration steps, the technique automatically performs all necessary microscope operations (stage translation, focus, sampling and analysis) on slides with up to 48 wells for as many different samples. It quantifies bacteria from differential interference contrast images, images showing cells that had been labeled by immunofluorescence with monoclonal antibodies, or images with cells labeled by a fluorescent DNA stain. With all evaluated samples, close agreement between the automated system and the assessor's visual counts was observed. This novel automated image grabbing and analysis procedure is applicable to the enumeration of specific taxa in clinical samples by both immunofluorescence and fluorescent in situ hybridization.

Automation↗
PubMed1997

Methods for microscopic characterization of oral biofilms: analysis of colonization, microstructure, and molecular transport phenomena.

Assessment of the role of biofilm microstructure in biofilm-specific activities requires non-destructive measurement techniques for parameterization of structural characteristics in parallel with relevant biochemical and physiological data. This paper briefly reviews some current methods for biofilm structural analysis, with emphasis on new developments in optical imaging and mathematical modeling methods. Fluorescence imaging studies of bacterial colonization events occurring on exposed model tooth surfaces indicated that bacterial adhesion to sessile organisms was of central importance to the early colonization process and that this occurred in a non-random manner. Structural studies of mature biofilms by confocal microscopy demonstrated the spatial distribution of individual species using fluorescent antibodies. Biofilms grown under different physiological conditions exhibited differences in structure, and methods were developed for parameterizing the spatial orientations of the bacteria. Diffusive processes within biofilm microstructures were studied using a random walk model in both 2-D and 3-D. Modeling of convective flow within biofilm microstructures was achieved by application of lattice Boltzmann methodology.

Bacteriological Techniques↗
PubMed1996

Competition for tetrahydrobiopterin between phenylalanine hydroxylase and nitric oxide synthase in rat liver.

Tetrahydrobiopterin (BH4) is an important cofactor for two hepatic enzymes, inducible nitric oxide synthase (iNOS) and phenylalanine hydroxylase (PAH), and competition for BH4 between the two enzymes might limit hepatic iNOS or PAH activity. To test this hypothesis, we determined whether conversion of phenylalanine to tyrosine was modified by changes in NO synthase activity, and conversely whether NO synthesis was limited by the rate of phenylalanine conversion to tyrosine in rat hepatocytes and perfused livers. NO production was decreased only slightly, when flux through PAH was maximized in isolated perfused livers, and in isolated hepatocytes only when BH4 synthesis was inhibited. Increases in NO synthesis did not reduce tyrosine formation from phenylalanine. Phenylalanine markedly increased biopterin synthesis, whereas arginine had no effect. Thus, basal BH4 synthesis appears to be adequate to support iNOS activity, whereas BH4 synthesis is increased to support PAH activity.

Animals↗
PubMed1996

Influenza immunization rates for Louisiana Medicare beneficiaries (1993-1995): a need for interventions.

Influenza is a disease, especially in the elderly, with potentially serious health and fiscal consequences. Vaccines, even though available and proven to be efficacious for prevention, appear to be underutilized in the Medicare population. This paper highlights influenza immunization rates from 1993-1995 for Louisiana Medicare eligible beneficiaries served by Louisiana providers. The authors discuss some of the current efforts underway to increase the number of influenza vaccinations. This was a retrospective study of claims based data on Medicare beneficiaries in Louisiana. Rates were also compared to other states from published Health Care Financing Administration data over the study period. In Louisiana, from 1993-1995, approximately 31% of Medicare beneficiaries age 65 years or older received an influenza vaccination that was paid for by Health Care Financing Administration. This finding indicates an attainment of half of the Department of Health and Human Services Year 2000 goal of 60% influenza immunization rate. The rate for Medicare African-American beneficiaries was approximately one half that of Caucasian beneficiaries. Overall, the billing data indicated that female beneficiaries received influenza immunization slightly more often than male. Medicare beneficiaries aged 75 to 84 years were immunized proportionally more than other age groups. The age group with the smallest percentage of immunized beneficiaries was 85 years or older. These results and rates obtained from the National Health Information Survey and Behavioral Risk Factor Surveillance System for the state collectively indicate marked opportunity for improvement in immunization rates for the State of Louisiana. Health care providers can assist and play an integral role in interventions designed to impact on this vulnerable population in order to meet the Department of Health and Human Services Year 1996 overall goal of 56% influenza immunization rate for all persons age 65 years or older.

Aged↗
PubMed1987

Low-dose phenobarbitone as an indicator of compliance with drug therapy.

1 To assess the potential value of low-dose phenobarbitone (PB) as a marker of compliance we studied the relationship between plasma level of PB and dose (2-16 mg daily) following 3 or 4 weeks treatment in healthy volunteers (n = 26) and in-patient volunteers (n = 7). 2 Also, to simulate poor compliance, PB levels were measured in some volunteers following alternate-day (n = 6) or short-term (n = 5) treatment with similar doses. These levels, expressed as the level: dose ratios (LDRs), did not overlap with those obtained following 3 or 4 weeks of daily PB intake. 3 To evaluate the efficacy of this marker in patients taking other drugs we gave a group of out-patients (n = 24) compound tablets containing B vitamins and a small dose (16 mg) of PB; their compliance over 2-5 weeks was assessed both by measuring plasma levels of PB and residual tablet counting. 4 In the latter study, as well as providing absolute evidence of good compliance by many patients, the plasma levels of PB proved particularly valuable when non-compliant individuals 'forgot' to bring their residual tablets. 5 We suggest that phenobarbitone, in doses low enough to be non-sedative and non-enzyme inducing, is potentially useful as a pharmacological indicator of compliance with drug therapy.

Adult↗
PubMed1986

Doctors' unawareness of the drugs their patients are taking: a major cause of overprescribing?

We studied the accuracy of both hospital and general practitioners' records of current drug treatment in consecutive patients who attended a general medical review clinic. Either the hospital or the general practitioner's records (obtained in a questionnaire), or both, were inaccurate for over 70% of 59 patients interviewed with their medicine. Most of the errors were due to patients taking drugs in addition to those shown in their records. Some of these were inappropriate, and many seemed unnecessary. It appears that neither hospital doctors nor general practitioners are fully aware which drugs their patients are taking, and this may contribute to overprescribing. We believe that considerable financial savings might be made if patients brought all their medicines to every consultation.

Awareness↗