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Biomedical subjects

R Thomas

Publications and source records attributed to R Thomas.

At least 739 records · Page 41Linked to original sources
PubMedDate not supplied

Multiregion contact systems for modelling STD epidemics.

This paper elicits properties of some multiregional contact systems for STD infections that are intended to assist the understanding of disease control strategies. To this end, a space-time SIS model is described that maintains the symmetry of contact that is inherent in the formation of sexual partnerships. It is demonstrated how the characteristic stability conditions of this model provide a framework for understanding the potential for sustained transmission after the introduction of the agent into a given region. Then, more complex SI specifications are derived that are particularly relevant to the transmission of HIV. These extensions include the introduction of alternative modes of travel and behavioural adaptations made in response to the circulation of HIV and the incidence of AIDS. The discussion suggests some additions to the systems that might enhance their applicability in practice.

Contact Tracing↗
PubMedDate not supplied

Human papillomavirus-11-associated recurrent respiratory papillomatosis is more aggressive than human papillomavirus-6-associated disease.

The aim of this study was to determine whether viral type (HPV-6 vs. HPV-11) could predict the clinical course of recurrent respiratory papillomatosis in children. Viral typing, using the polymerase chain reaction, was performed on laryngeal biopsies of 61 patients treated at Children's Hospital of Michigan. HPV-6 was detected in 29 of the patients' biopsies and HPV-11 in 32 biopsies. HPV-11 was more common among the African-American patients than among Caucasians (P = 0.001). Patients with HPV-11 were diagnosed at a younger age (36.2 vs. 48.2 months; P = 0.04) and were more likely to have active disease (P = 0.0311) at the time of this study. They tended to have longer periods of disease activity (8 years vs. 5 years; P = 0.026), required more surgical procedures (42 procedures/patient vs. 13.6; P = 0.02), and more procedures per patient, per year (2.9 vs. 5.3; P = 0.0164). Three of the patients infected with HPV-11 developed invasive papillomatosis and bronchogenic squamous cell carcinoma, and two of these patients died of disease. Our findings suggest that HPV-11 infection confers a more aggressive course to recurrent respiratory papillomatosis.

Child↗
PubMedDate not supplied

Proposed in situ secondary ion mass spectrometry on Mars.

Secondary ion mass spectrometry is a powerful analytical tool, which has the potentiality, through molecular ion emission, of detecting minor phases, as well as the unique capability of directly measuring isotope abundances in mineral or organic phases without any prior physical, chemical or thermal processing. Applied to the in situ analysis of the Martian regolith, it can provide evidence of the presence of carbonates and, by inference (if carbonates constitute significant deposits), of past liquid water--a necessary condition for the development of life. In addition, oxygen isotopic composition of carbonates preserves a record of the temperature at which this phase precipitated and may therefore help decipher the past climatology of Mars. Detection of a carbon isotopic composition shift between carbonates and organic matter (on Earth, the result of a kinetic fractionation effect during photosynthesis) would provide a definite clue regarding the existence of a past biochemical activity on Mars.

Carbon Isotopes↗
PubMedDate not supplied

GH responses to growth hormone releasing factor in depression.

The growth hormone (GH), thyrotrophin (TSH) and prolactin response to growth hormone releasing factor (GRF) was investigated in 18 patients suffering from major depression with melancholia and in 18 age- and sex-matched normal controls. There was no significant difference in the GH response to GRF stimulation between the patients and controls and in neither subject group was there a demonstrable TSH or prolactin response to GRF. These findings indicate that the pathophysiology underlying the blunted GH response to pharmacological challenge, demonstrated in other studies, must lie at a suprapituitary level.

Depressive Disorder↗
PubMedDate not supplied

Use of the IDEIA ELISA to detect Chlamydia psittaci (ovis) in material from aborted fetal membranes and milk from ewes affected by ovine enzootic abortion.

The IDEIA ELISA was used to detect Chlamydia psittaci (ovis) antigen in ewes' milk to which were added serial dilutions of chlamydiae titrated as inclusion forming units (ifus) in McCoy cell tissue culture. The test was able to detect as few as 35 ifus/ml of the organism. The ELISA was then used to detect chlamydial antigen in fetal membranes and milk from ewes clinically affected with ovine enzootic abortion (OEA). The results were compared with results of isolation of chlamydiae in McCoy cell tissue culture from the same material. The fetal membranes of 17 of 19 ewes were positive for chlamydia when tested with the ELISA but chlamydia could be cultured from only 15 of them. Milk samples from 26 ewes which had aborted between 1 and 34 days previously were tested: chlamydiae could not be cultured from any of them and only one was positive when tested by the ELISA. The results show that the IDEIA ELISA is a sensitive test for the detection of C. psittaci (ovis) antigens. The positive results to this test for the three samples from which chlamydiae could not be cultured suggest that the test is not as specific as culture or that it detected dead organisms. Chlamydiae do not appear to be excreted in the milk of ewes affected with OEA.

Abortion, Veterinary↗
PubMedDate not supplied

A comparison of the Cohen-Mansfield agitation inventory with the CERAD behavioral rating scale for dementia in community-dwelling persons with Alzheimer's disease.

In a group of 242 community-dwelling patients with Alzheimer's disease (AD), a longitudinal comparison was made of two caregiver-administered instruments for assessment of behavioral disturbance; the Cohen-Mansfield Agitation Inventory (CMAI) and the CERAD Behavioral Rating Scale for Dementia (BRSD). We examined records of the 206 patients with baseline and 12-month follow-up data for the CMAI and the BRSD who also had tests of cognitive (Mini-mental State; MMSE) and global function (Clinical Dementia Rating; CDR and Functional Assessment Staging; FAST). Among 114 AD subjects, the correlation between total CMAI at baseline and 1 month readministration was 0.83 (p < 0.0001). In the same subjects, stratified into 5 groups by MMSE scores, the correlations between BRSD baseline and 1-month scores ranged from 0.70-0.89 (p < 0.0001). There was high correlation between total scores of both instruments at baseline and 12 months. In addition, all CMAI subscales except Verbally Aggressive correlated significantly with total BRSD score at both time points. At baseline, BRSD subscales for irritability/aggression, behavioral dysregulation and psychotic symptoms and at 12 months, irritability/aggression and behavioral dysregulation correlated with total CMAI scores. Neither scale changed significantly over 1 year, but there was wide individual variation. CMAI and BRSD scores correlated with 1-year change in the FAST, but not with MMSE or CDR (which weighs cognition heavily), suggesting that behavioral disturbance may be more strongly related to ability to manage activities of daily living (executive function) than to other aspects of cognition. The CMAI and BRSD appear to be interchangeable as measures of agitation, with the CMAI possibly more useful for patients who lack language and the BRSD more sensitive to apathy and depression.

Activities of Daily Living↗
PubMedDate not supplied

Malignant oncocytoma of the nasal cavity: a case report.

Malignant oncocytoma is a rare clinical entity and is most commonly seen in the salivary glands. Its occurrence in the nasal cavity is extremely rare, and only 4 such cases have been reported in the literature. The authors report one such case in a 60-year-old woman, which presented as a slow-growing nasal mass arising from the nasal septum, with no lymph node metastasis, which was successfully managed by a combined modality of treatment-surgery followed by radiation therapy. The relevant literature has been reviewed. The case is discussed as a possible differential diagnosis for a mass in the nose.

Adenoma, Oxyphilic↗