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Biomedical subjects

R L Cook

Publications and source records attributed to R L Cook.

41 records · Page 3Linked to original sources
PubMedDate not supplied

Heterodera glycines: density-based gradient separation of eggs.

An efficient technique was developed for separating early and late stages of embryonic development in eggs of Heterodera glycines. This technique takes advantage of density changes that occur during embryogenesis in the developing embryo and egg to partition the egg within a sucrose step gradient. Sorted samples of eggs separated with 82% enrichment for pre-gastrula early embryos and 93% enrichment for first and second stage unhatched juveniles as late embryos. Subpopulations enriched for either developmental stage are available for use in generating stage-specific cDNA libraries, normalization of subpopulations to synchronize development, biochemical characterization, and many other uses.

Animals↗
PubMedDate not supplied

Emerging role of lactobacilli in the control and maintenance of the vaginal bacterial microflora.

The vaginal microflora of healthy asymptomatic women consists of a wide variety (two to five isolates at any one time) of anaerobic and aerobic bacterial genera and species dominated by the facultative, microaerophilic, anaerobic genus Lactobacillus. That the vaginal flora forms part of a dynamically changing ecosystem is evident from the variable prevalence and population levels of each bacterial species detected with repetitive longitudinal sampling, with pregnancy, and with stage in the menstrual cycle. This review emphasizes the role that vaginal lactobacilli may play in control of the vaginal microflora and maintenance of the normal state. Lactobacilli possess many antagonistic properties and produce many metabolites that may be important in maintaining dominance in the vagina. Contradictory data from previous studies regarding the impact of factors such as contraception, catamenial products, and physiologic elements on the vaginal microflora are due in part to poor study design and differences in methodology. Well-designed and controlled investigations with large numbers of individuals in each group are needed, and the limitations of the methodology for such investigations must be considered. Studies of the normal flora, exploring the interaction of lactobacilli and other bacterial species, must be performed before the pathologic processes resulting in vaginitis or systemic sequelae are investigated.

Bacteria↗
PubMedDate not supplied

Abnormal hormone levels in men with coronary artery disease.

Plasma concentrations and urinary excretions of various hormones and hormone metabolites were measured in four groups. Group 1 was composed of 13 men with prior myocardial infarction; Group 2 contained 35 clinically normal men; Group 3 consisted of 44 men with normal coronary arteriograms; and Group 4 was composed of 25 men with severe coronary artery disease shown on arteriogram but no infarction. There were four major findings: Group 1 had significantly higher 24-hour mean plasma concentrations of estrone (E1), dehydroisoandrosterone (DHA), and dehydroisoandrosterone sulfate (DHAS) than Group 2, while Group 3 had the same levels as Group 4; Group 4 had significantly lower urinary excretion of androsterone glucuronide (AG) than Group 3, while Group 1 excreted normal amounts. There are three possible explanations for these findings: 1) myocardial infarction occurring in men with coronary artery disease may elevate the plasma levels of E1, DHA, and DHAS and eliminate the preinfarction depression of urinary AG levels; 2) higher than average levels of E1, DHA, DHAS, and AG may favor the development of infarction in men with coronary artery disease; 3) higher than average levels of E1, DHA, DHAS, and AG may favor survival from any infarction that occurs in men with coronary artery disease. Experimental and epidemiological evidence seems to favor the third possibility.

Adult↗
PubMedDate not supplied

Psychosocial responses to myocardial infarction.

This paper has presented some psychosocial factors believed to contribute to the incidence of coronary artery disease. In addition to the recognized risks, Type A behavior was identified as particularly predisposing to the incidence of CAD. A pattern of psychosocial responses to MI, as a symptomatic manifestation of CAD, was discussed in relation to a specific patient and to the nursing interventions employed. These responses are not peculiar to individuals who suffer an MI, but are common human responses to threat by illness or injury, and as such present a challenge to nurses for appropriate therapeutic intervention.

Anxiety↗