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Biomedical subjects

L Thomas

Publications and source records attributed to L Thomas.

At least 163 records · Page 9Linked to original sources
PubMed1999

Effects of chirality at Tyr13 on the structure-activity relationships of omega-conotoxins from Conus magus.

The effects of chirality inversions of Tyr13 on the structure-activity relationships of omega-conotoxins MVIIA and MVIIC were examined using a combination of 2D 1H NMR spectroscopy and radioligand binding studies specific for N-type ([125I]GVIA) and P/Q-type ([125I]MVIIC) voltage-sensitive calcium channels (VSCCs). A comparison of the Halpha secondary shifts suggests that the structural scaffolds of MVIIA and MVIIC are little altered by the L- to D- inversion of Tyr13; however, the conformations of several residues in loop 2 (residues 9-14) are significantly altered. The experimentally determined 3D structure of [D-Y13]MVIIA indicates that the positions of key residues in this loop which are involved in the binding of MVIIA to the N-type VSCC (Tyr13, Arg10, and Leu11) are so changed as to render the peptide unrecognizable by its cognate ion channel. The large reduction in potency observed for MVIIA and MVIIC at both N-type and P/Q-type VSCCs is likely to stem from the change in conformation and orientation of loop 2.

Amino Acid Sequence↗
PubMed1999

Angiotensin-converting-enzyme gene insertion/deletion polymorphism and response to physical training.

BACKGROUND: The function of local renin-angiotensin systems in skeletal muscle and adipose tissue remains largely unknown. A polymorphism of the human angiotensin converting enzyme (ACE) gene has been identified in which the insertion (I) rather than deletion (D) allele is associated with lower ACE activity in body tissues and increased response to some aspects of physical training. We studied the association between the ACE gene insertion or deletion polymorphism and changes in body composition related to an intensive exercise programme, to investigate the metabolic effects of local human renin-angiotensin systems. METHODS: We used three independent methods (bioimpedance, multiple skinfold-thickness assessment of whole-body composition, magnetic resonance imaging of the mid-thigh) to study changes in body composition in young male army recruits over 10 weeks of intensive physical training. FINDINGS: Participants with the II genotype had a greater anabolic response than those with one or more D alleles for fat mass (0.55 vs -0.20 kg, p=0.04 by bioimpedance) and non-fat mass (1.31 vs -0.15 kg, p=0.01 by bioimpedance). Changes in body morphology with training measured by the other methods were also dependent on genotype. INTERPRETATION: II genotype, as a marker of low ACE activity in body tissues, may conserve a positive energy balance during rigorous training, which suggests enhanced metabolic efficiency. This finding may explain some of the survival and functional benefits of therapy with ACE inhibitors.

Adipose Tissue↗
PubMed1999

Occurrence of monosialosyl pentahexaosylceramide GalNAc-GM1 as specific tumor-associated ganglioside of human head and neck squamous cell carcinomas.

In a recent study of the ganglioside profiles of human head and neck squamous cell carcinomas versus normal tissue, one unidentified GX ganglioside was found exclusively in tumor extracts, migrating between GM1 and GD3 by thin-layer chromatography. To determine the chemical structure of this ganglioside which accounted for 3-8% of the total gangliosides, the lipid samples were pooled and separated by high-pressure liquid chromatography to obtain individual ganglioside species purified to homogeneity. The tumor-associated GX ganglioside was analyzed by gas-liquid chromatography, mass spectrometry and immunostaining on thin-layer plates with mouse monoclonal antibodies after enzymatic cleavage. The data allowed the identification of GX ganglioside as GalNAc-GM1 that has been reported as a very minor brain ganglioside in humans. Thus, GalNAc-GM1 is a specific tumor-associated ganglioside in human head and neck squamous cell carcinomas that could be potentially valuable for clinicians.

Carcinoma, Squamous Cell↗
PubMed1999

The effect of parental monetary sanctions on the vaccination status of young children: an evaluation of welfare reform in Maryland.

OBJECTIVE: To determine whether financial sanctions to Aid to Families With Dependent Children (AFDC) recipients can be used to improve vaccination coverage of young children. DESIGN: Randomized controlled trial. SETTING: Six AFDC jurisdictions in Maryland. INTERVENTION: Recipients of AFDC were randomized to the experimental or control group of the Primary Prevention Initiative. Families in the experimental group were penalized financially for failing to verify that their children received preventive health care, including vaccinations; control families were not. PARTICIPANTS: Children aged 3 to 24 months from assigned families were randomly selected for the evaluation (911 in the experimental, 864 in the control, and 471 in the baseline groups). MAIN OUTCOME MEASURES: Up-to-date for age for diphtheria and tetanus toxoids and pertussis (DTP), polio, and measles-mumps-rubella (MMR) vaccines; missed opportunities to vaccinate; and number of visits per year. ANALYSIS: Comparisons among baseline and postimplementation years 1 and 2. RESULTS: Vaccination coverage of children was low. Less than 70% of children were up-to-date for age for polio and MMR vaccines; slightly more than 50% were up-to-date for DTP vaccine. Up-to-date rates differed little among baseline, experimental, and control groups. Over time, there was a decrease in missed opportunities, and more children made at least 1 well-child visit; however, neither improvement resulted in a change in vaccination status. CONCLUSIONS: The Primary Prevention Initiative did not contribute to an increase in vaccination coverage among these children. Minimal economic sanctions alone levied against parents should not be expected substantially to affect vaccination rates.

Aid to Families with Dependent Children↗
PubMed1999

The prevalence and determinants of health care-seeking behavior for urinary incontinence in United Arab Emirates women.

The aim of this study was to determine the prevalence and sociodemographics of urinary incontinence (UI) in women in the United Arab Emirates (UAE). Women at risk, such as multiparous and climacteric women, were selected from the community (n = 200) and health-care centers (n = 200) and interviewed about inappropriate urine loss in the past 12 months, using a structured and pretested questionnaire. Of these, 81 (20.3%) admitted UI; only 25 of these (30.9%) had sought medical advice. The reasons were embarrassment (38.2%), choice of self-treatment because of low expectations from medical care (38.2%), and preferring to discuss the matter with friends, assuming that UI is normal (23.3%). Sufferers were troubled by their inability to pray (90%) and to have sexual intercourse (33.3%). Perceived causes of UI were paralysis (45%), childbirth (35.4%) and old age or menopause (33.7%). UI is common yet underreported by UAE women because of cultural attitudes and inadequate public knowledge.

Adult↗
PubMed1999

Cytoplasmic accumulation of peanut agglutinin-binding glycoconjugates in the cells of primary melanoma correlates with clinical outcome.

In an experimental model, human melanoma cell lines enriched for cells that express the glycoconjugate B-D galactose N-acetyl-D-galactosamine, which reacts with the peanut agglutinin lectin (PNA), are associated with an increase in the frequency of metastases. We previously showed that this glycoconjugate is expressed on the cells of some primary melanomas in humans and that such cells are found selectively in melanomas with a high risk for developing metastases and causing death. Using fixed archival tissues from 99 primary melanomas and lectin histochemistry, we found 65 tumors that contained melanoma cells that were PNA-positive. PNA-reactive cells were not identified in normal melanocytes or in the nevocytes of 24 nevi. PNA-reactive material accumulates adjacent to the nucleus in the area of the Golgi apparatus, initially as a tiny dot, but later in quantities sufficient to displace and indent the nucleus, producing a signet ring cell-like appearance. Tumor cells containing PNA-reactive material were associated with more evolved, deeper, and thicker tumors. Two melanomas up to Clark level II were PNA positive (20%), compared with 60% of level III, 76% of level IV, and 100% of level V. Five of 13 tumors less than 0.76 mm thick (39%) were positive, compared with 50% of tumors 0.76 to 1.49 mm thick, 64% of tumors 1.5 to 2.99 mm thick, and 85% of tumors 3 mm thick or thicker. PNA-reactivity was negatively correlated with disease-free survival (PNA-negative, 49.2+/-23 months; PNA-positive grade 1, 41.6+/-26 months and PNA-positive grade 2, 24.4+/-23 months), survival rate 5 years after initial treatment (PNA-negative, 84.8%; PNA-positive grade 1, 63.8%; and PNA-positive grade 2, 31.3%) and disease-free survival at 5 years after initial treatment (PNA-negative, 69.7%; PNA-positive grade 1, 53.2%; and PNA-positive grade 2, 25%).

Cytoplasm↗
PubMed1999

Treatment of squamous cell anal canal carcinoma with pulsed dose rate brachytherapy. Feasibility study of a French cooperative group.

BACKGROUND AND PURPOSE: To evaluate the feasibility of pulsed dose rate (PDR) brochytherapy in squamous cell anal canal carcinoma (SCACC). MATERIALS AND METHODS: In this study a series of 19 patients with SCACC were included between 1995 and 1997. All patients were treated with curative intent with external beam radiotherapy (EBRT) (44-50 Gy) and one or two cycles of concomitant fluorouracilcisplatinum. After a gap of 2-3 weeks PDR interstitial brachytherapy was performed with a rigid needles technique. The dose was between 10-25 Gy (PARIS system). RESULTS: All patients are alive. No severe grade 3-4 toxicity was encountered. One local relapse one metastatis were seen in two distinct patients. There was no dysfunction of the after loading machine. CONCLUSION: The feasibility of PDR brachytherapy appears good in SCACC. It is an attractive alternative to low dose rate brachytherapy.

Adult↗
PubMed1999

The Mitral Regurgitation Index: an echocardiographic guide to severity.

OBJECTIVES: The purpose of this study was to develop a semiquantitative index of mitral regurgitation severity suitable for use in daily clinical practice and research. BACKGROUND: There is no simple method for quantification of mitral regurgitation (MR). The MR Index is a semiquantitative guide to MR severity. The MR Index is a composite of six echocardiographic variables: color Doppler regurgitant jet penetration and proximal isovelocity surface area, continuous wave Doppler characteristics of the regurgitant jet and tricuspid regurgitant jet-derived pulmonary artery pressure, pulse wave Doppler pulmonary venous flow pattern and two-dimensional echocardiographic estimation of left atrial size. METHODS: Consecutive patients (n = 103) with varying grades of MR, seen in the Adult Echocardiography Laboratory at UCSF, were analyzed retrospectively. All patients were evaluated for the six variables, each variable being scored on a four point scale from 0 to 3. The reference standards for MR were qualitative echocardiographic evaluation by an expert and quantitation of regurgitant fraction using two-dimensional and Doppler echocardiography. A subgroup of patients with low ejection fraction (EF < 50%) were also analyzed. RESULTS: The MR Index increased in proportion to MR severity with a significant difference among the three grades in both normal and low EF groups (F = 130 and F = 42, respectively, p < 0.0001). The MR Index correlated with regurgitant fraction (r = 0.76, p < 0.0001). An MR Index > or =2.2 identified 26/29 patients with severe MR (sensitivity = 90%, specificity = 88%, PPV = 79%). No patient with severe MR had an MR Index <1.8 and no patient with mild MR had an MR Index >1.7. CONCLUSIONS: The MR Index is a simple semiquantitative estimate of MR severity, which seems to be useful in evaluating MR in patients with a low EF.

Adult↗
PubMed1999

Excision repair defect in Rothmund Thomson syndrome.

Rothmund Thomson syndrome is a rare autosomal recessive skin disorder. The main clinical feature is poikiloderma appearing in early childhood associated with skeletal abnormalities. Early occurrence of malignancies is another relevant feature. Here we describe the clinical features of 2 patients with Rothmund Thomson syndrome who were investigated for the in vitro DNA repair capacities of blood cells following UVC radiation exposure. DNA excision repair, assessed with unscheduled DNA synthesis following UVC exposure, was decreased in both patients. Such a defect might explain the patients' sensitivity to sunlight and the relatively high risk of cancer associated with this syndrome.

Adolescent↗
PubMed1999

Lichenoid cutaneous drug reaction at injection sites of granulocyte colony-stimulating factor (Filgrastim).

Colony-stimulating factors are widely used for bone marrow recovery after chemotherapy. Various cutaneous side-effects have been described in most cases involving neutrophils. We report the first case of lichenoid reaction at injection sites of granulocyte colony-stimulating factor (G-CSF) in a 40-year-old patient treated for breast cancer. The eruption cleared after drug withdrawal, no recurrence was observed after drug replacement by granulocyte-macrophage colony-stimulating factor. Mainly lymphocyte-mediated lichenoid eruption to G-CSF was shown. Cutaneous side-effects to G-CSF do not share unequivocal pathogeny based on stimulation of neutrophils.

Adult↗
PubMed1999

Development of a scale to assess nurses' knowledge of stroke: a pilot study.

OBJECTIVE: To develop and test an evidence-based scale to assess nurses' knowledge of stroke. DESIGN: Question development by a multidisciplinary group of experts in stroke. Two self-completion questionnaire surveys. SETTING: Two stroke units, one general medical and two elderly care wards in three hospitals in the North-East of England. SUBJECTS: Fifty-eight qualified nurses. INTERVENTIONS: Scale to assess nurses' knowledge of stroke. RESULTS: The overall response rate was 60%. Nurses on stroke units knew more about stroke than those in medical/elderly care wards. The scale was capable of discriminating between stroke units and medical /elderly care wards: mean difference was 4.18 (95% confidence intervals 1.68-6.69; p <0.001). Cronbach's alpha was 0.7 indicating adequate internal consistency. Item non-response did not exceed 10% for any question. CONCLUSIONS: We have developed a knowledge of stroke scale capable of discriminating between nurses based in stroke units and medical/elderly care wards, with low item non-response and adequate internal consistency. The scale is suitable for use as a component of studies evaluating the nursing of stroke patients.

Attitude of Health Personnel↗
PubMed1999

Job satisfaction and intent to continue working among individuals with serious mental illness.

This study investigated the relationship between job satisfaction and the intention to continue working in a sample of 87 individuals with psychiatric disabilities who worked in supported or supervised employment. Data were collected from respondents in Columbus, Ohio in 1996. After controlling for selected correlates (education, length of employment, contract type, social support, and attitudes concerning pay and toward work), standard multiple regression analyses indicated that job satisfaction was a significant predictor of intent to continue working. Analyses also indicated that respondents who completed high school and who said that they worked primarily for the money were less likely to want to continue working at current jobs. These findings may be used to improve the vocational success of individuals with psychiatric disabilities who work in supported and supervised employment.

Adult↗
PubMed1999

Renal handling of endogenous human chorionic gonadotrophin in preeclampsia.

OBJECTIVE: To test the hypothesis that the elevated maternal serum concentration of human chorionic gonadotrophin (hCG) in preeclampsia is due to altered renal handling of the hormone. SETTING: Department of Obstetrics and Gynecology, Al Ain Hospital, United Arab Emirates, a tertiary center affiliated with the Faculty of Medicine and Health Sciences, UAE University. METHODS: The renal clearances and handling of endogenous creatinine and human chorionic gonadotrophin were compared in 14 normotensive volunteer and 14 preeclamptic mothers who received oral hydration at 34-37 weeks' gestation. The hCG content in the placentas was estimated immunohistochemically after delivery. RESULTS: Maternal serum concentration of hCG (p = 0.0057), the placental hCG immunopositive cell (p < 0.0001), and syncytial knot counts (p < 0.0001) were significantly higher in preeclamptic mothers. The renal clearances of endogenous creatinine and hCG and fractional hCG clearance were not significantly different in both groups. Significantly increased amounts of hCG were filtered (p = 0.007) and excreted (p = 0.007) by preeclamptic mothers. Only a small but fixed proportion of the filtered load of hCG is excreted in both groups and there was a positive correlation (r = 0.5, p = 0.005) between filtered and excreted loads of hCG. CONCLUSION: The results indicate increased placental content of hCG in preeclampsia. The resultant increased maternal serum concentration is probably sustained by the mechanism of renal handling of the hormone.

Analysis of Variance↗
PubMed1999

Multicenter trial of the quantitative BTA TRAK assay in the detection of bladder cancer.

BACKGROUND: Human complement factor H-related protein (hCFHrp) is produced by several bladder cancer cell lines and may be useful as a cancer marker. The aim of this study was to compare urinary hCFHrp and cytology for the detection of bladder cancer found by cystoscopy in patients with suggestive signs, symptoms, or preliminary test results. METHODS: The BTA TRAK assay, a quantitative enzyme immunoassay for the bladder tumor-associated antigen in urine, was compared with exfoliative cytology in 220 patients (155 men, 65 women; mean age, 64.2 years) presenting with signs, symptoms, or preliminary diagnostic results suggestive of this disease. Cystoscopy was the standard of detection. RESULTS: In the 100 patients found to have bladder cancer, the overall sensitivities of the BTA TRAK assay (at a previously determined decision threshold of 14 kilounits/L) and cytology were 66% (66 of 100) and 33% (33 of 100), respectively (P <0.001). The BTA TRAK assay proved to be statistically more sensitive than cytology for tumor grades I and II and for stage Ta and T1 tumors. In contrast, the overall specificity of the BTA TRAK assay in the 120 patients without cystoscopically confirmed bladder cancer was 69% (83 of 120) and that of cytology was 99% (119 of 120; P <0.001). The specificity of the BTA TRAK assay was higher in patients without benign or malignant genitourinary disease other than bladder cancer (76%; n = 89) than in patients with these conditions. When the BTA TRAK assay and cytology were used together such that a positive result in either test was scored as positive and the results compared with those of the BTA TRAK assay alone, increases in overall sensitivity and equivalent specificity were observed. CONCLUSION: Because of its relatively high sensitivity, the BTA TRAK assay could complement cytology as an adjunct to cystoscopy in the diagnosis and follow-up of most patients with bladder cancer.

Adult↗
PubMed1999

Images within the allied health professions.

The purpose of this study was to identify the perceived images, understanding, and respect shared by employed members of six allied health professions and to determine the nature and extent of interactions these professions share as members of the hospital team. The results indicate a large variance in levels of understanding and respect among the professions. Most responded that they understood the other professions but the other professions did not understand them. The results also indicate that the professions interact on an average of no more than five hours per week, with their common interactive roles being peer relationships.

Allied Health Personnel↗
PubMed1999

This is my story: a descriptive analysis of a peer education HIV/STD risk reduction program for women living in housing developments.

Descriptive, qualitative data was collected from 30 women who participated in the Centers for Disease Control and Prevention-funded Perinatal HIV Reduction and Education Demonstration Activities (PHREDA) Project. Women were primarily heterosexual, welfare-dependent, African-American mothers. Staff trained women to conduct HIV/STD education as peer volunteers. The theory-based educational components consisted of role model stories developed by women about their experiences with HIV/STDs and discussion groups to build behavioral and communication skills. Women were given role-model stories and safer sex supplies to initiate conversations about women's health and sexual safety in their communities. PHREDA groups allowed women to identify their risk reduction, sexual, and family issues. Role model stories provided a validating medium through which high-risk women explored reproductive health risk and planned steps toward behavioral change. Descriptive data from peer volunteers can provide an important perspective on small group, peer-based community HIV/STD reduction interventions.

Black or African American↗