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Biomedical subjects

A D White

Publications and source records attributed to A D White.

53 records · Page 3Linked to original sources
PubMed1990

Features of multiple sclerosis in older patients in South Wales.

Multiple sclerosis (MS) may occur outside the commonly accepted age range. Data relating to features of MS in a population in South Wales have been analysed to find features which characterise older patients. The older patients are more severely disabled due to the accumulation of visual defects and motor signs and symptoms. The course of the disease is marked by single localised attacks with long remissions. Those with onset over 50 years deteriorate more rapidly, but in those who were over 50 at the time of interview, this did not occur. It is suggested that there is no essential difference in MS in older patients, but there may be features which reflect normal ageing and diseases commoner in old age.

Adolescent↗
PubMed1982

Type A behavior and elevated physiological and neuroendocrine responses to cognitive tasks.

Qualitatively distinct patterns of cardiovascular and neuroendocrine responses were observed in male college students during mental work and during sensory intake task performance. During mental work, Type A (coronary-prone) subjects showed greater muscle vasodilatation and more enhanced secretion of norepinephrine, epinephrine, and cortisol than Type B subjects. During sensory intake, Type A hyperresponsivity was found for testosterone and, among those subjects with a positive family history of hypertension, for cortisol. As a demonstration of combined cardiovascular, sympathetic nervous system, and neuroendocrine hyperresponsivity to specific cognitive tasks in Type A subjects, this study breaks ground in the search for mechanisms mediating the increased coronary disease risk among Type A persons.

Behavior↗
PubMed1980

A method utilizing human lymphocytes with in vitro metabolic activation for assessing chemical mutagenicity by sister-chromatid exchange analysis.

A technique using human lymphocytes together with an Ames-type microsomal (S9) activation system for testing indirect chemical mutagens has been developed and examined. The cytotoxic drug cyclophosphamide (CP), which only displays mutagenic properties after metabolic activation, was used as a test chemical and mutagenicity assessed in terms of sister-chromatid exchange (SCE) induction. Direct exposure of lymphocytes to CP and S9 mix produced increases in the yield of SCE for CP concentrations down to 10(-6) M. Exposure times of 30, 60 and 120 min commencing at the beginning of cell culture or after 48 h gave different ranges of detection and response with later treatment being more effective for SCE induction. Variations in relative proportions of the S9 mix and culture medium constituents affected the lymphocytes' tolerance of toxic factors and modified the mutagen's effect. CP pre-incubated with S9 mix for 1 h before adding to the lymphocyte cultures also produced increases in SCE levels but the method was complicated and did not reduce toxicity. Direct addition of CP and S9 mix to the lymphocytes without prior pre-incubation showed maximum sensitivity, minimum toxicity and was a simpler, more reliable technique.

Biotransformation↗
PubMed1980

In vitro induction of SCE in human lymphocytes by epichlorohydrin with and without metabolic activation.

Human lymphocytes cultured for 73 h in the presence of BrdU were exposed to epichlorohydrin (ECH) with and without metabolic activation. Cells exposed for the entire culture time without activation showed a significant dose related increase in SCE yield. Exposure for the final 25 h only showed a similar response but with increased tolerance. The presence of S9 mix significantly reduced the effect of ECH compared with a similar exposure without activation. Without activation 4 X 10(-4) M ECH produced a 3-fold increase in the incidence of SCE over the control level. However, with S9 mix a concentration of 10(-3) M ECH was required to produce such an increase indicating that S9 mix may have a detoxifying effect.

Animals↗
PubMed1977

Photochemotherapy of psoriasis using methoxsalen and sunlight. A controlled study.

Fifty-one patients with psoriasis were treated with oral methoxsalen and sunlight exposure. Twelve of these patients received either methoxsalen or placebo prior to whole-body exposure. The remainder were treated with methoxsalen and sunlight to one side of the body and sunlight alone to the other. The conventional dose of methoxsalen (0.6 mg/kg) was compared with a low dose (0.3 mg/kg). Oral methoxsalen when used in the higher dose followed by sun exposure is an effective treatment for psoriasis. Accurate ultraviolet dosimetry is essential to avoid phototoxic burns. The advantages and disadvantages of solar photochemotherapy are discussed.

Clinical Trials as Topic↗
PubMed1972

Zoonotic infections in military scout and tracker dogs in Vietnam.

Significant levels of antibodies indicative of a variety of zoonotic infections were demonstrated in sera collected from 64 U.S. military scout and tracker dogs after service in the Republic of Vietnam (RVN). Scrub typhus antibodies were found in 45% of the specimens, melioidosis in 19%, group B arbovirus in 49%, and leptospirosis in 62%. Only 38% of the seropositive reactions for leptospirosis could be related to overseas infections. Tests were conducted on paired sera obtained from 32 of the dogs before service in RVN. Significant increases in titer were demonstrated with scrub typhus, melioidosis, leptospirosis, plague, group B arbovirus, and Rickettsia canada antigens. After 2 to 6 months of service in RVN, 8 of 19 dogs developed antibody titers to at least one of four zoonotic diseases. Only 3 of 45 dogs with 7 or more months of service failed to develop antibodies to one or more of the agents. The serological findings pose questions on the potential epidemiological importance and veterinary significance of scrub typhus, group B arbovirus, leptospirosis, and melioidosis infections in dogs.

Animals↗
PubMedDate not supplied

Serum cholesterol and 20-year mortality in black and white men and women aged 65 and older in the Evans County Heart Study.

Serum cholesterol and 20-year mortality rates were studied in 396 Evans County black and white men and women who were 65 years and older and free of prevalent coronary heart disease (CHD) at baseline examination in 1960 to 1962. Previous reports on Evans County men and women younger than 65 found cholesterol levels to be significantly associated with all-cause and CHD mortality in white men, with CHD mortality in black men, and with cardiovascular disease mortality in white women. The independent role of total serum cholesterol as a predictor of CHD and all-cause mortality in the 65-and-older age group was evaluated using Cox proportional hazards models. Among white men, serum cholesterol level was positively associated with CHD mortality (relative risk of 1.54, P < 0.05 for an increment of 40 mg/dL [1.03 mmol/L], or one standard deviation in cholesterol). A significant J-shaped relationship of cholesterol with all-cause mortality was found among white men. Among black women, cholesterol was negatively associated with all-cause mortality. Neither all-cause nor CHD mortality was related to serum cholesterol among black men or white women. Although based on small numbers, the results of this study suggest that in Evans County, total serum cholesterol is an independent predictor of mortality in white men aged 65 and over, while these results should not be generalized to other race-gender groups in this cohort.

Black or African American↗