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Biomedical subjects

C Bowles

Publications and source records attributed to C Bowles.

22 records · Page 2Linked to original sources
PubMedDate not supplied

Hypobaric hypoxia and villous trophoblast: evidence that human pregnancy at high altitude (3600 m) perturbs epithelial turnover and coagulation-fibrinolysis in the intervillous space.

Spatial relationships between fibrin-type fibrinoid and regions of villous trophoblast were examined in order to address two main questions: [1] is high-altitude pregnancy accompanied by changes in the sizes of trophoblast compartments (cytotrophoblast, syncytiotrophoblast, denudation sites)?, and [2] do highland placentae differ in the amounts and distribution patterns of perivillous fibrin-type fibrinoid? Placentae were collected from two ethnic groups completing term pregnancies at low (400 m above sea level; n=25) and high (3600 m; n=45) altitude in Bolivia. Masson trichrome-stained sections were sampled randomly and analysed stereologically to estimate compartment volumes and surfaces. Comparisons were drawn using variance, Chi-squared and contingency table analyses. At high altitude, birthweights were 265 g lower and placentas had a larger intervillous space (270 cf 181 cm(3)), less fibrin-type fibrinoid (4.1 cf 8.4 cm(3) by volume; 2570 cf 4430 cm(2) by surface area), less villous trophoblast (50 cf 73 cm(3)) and a smaller villous surface (5.6 cf 7.0 m(2)). Volumes were reduced in all syncytiotrophoblast compartments (with and without nuclear aggregations). Cytotrophoblast was maintained and its relative volume increased significantly (from 2.7 to 3.6 per cent of trophoblast volume). Decreases in villous surface area affected primarily thinner (nuclear aggregate-free) regions of syncytium. Regardless of altitude, fibrin-type fibrinoid was deposited non-randomly: it was preferentially located at sites of trophoblast denudation. Although no altitudinal differences in fibrin-type fibrinoid patterns were detected, absolute surfaces were diminished on denuded and thinner regions of trophoblast but not on syncytial knots or bridges. Ethnic differences at low altitude (relatively greater deposits on denudations in Amerindians) were minimized at high altitude. We conclude that pregnancy at high altitude alters the epithelial steady state (towards cytotrophoblast and away from syncytiotrophoblast) and the coagulation-fibrinolysis steady state in the intervillous space (to favour fibrinolysis over coagulation). Thinner regions of syncytiotrophoblast may be the main sites of greater fibrinolytic or anticoagulatory activity. The findings are partly consistent with results from in vitro studies which indicate that hypoxia stimulates proliferation of cytotrophoblast but impairs fusion into syncytium.

Adult↗
PubMedDate not supplied

Measure of attitude toward menopause using the semantic differential model.

A semantic differential instrument that measures adult women's attitudes toward menopause was constructed and validated. A volunteer sample of 504 women, 18 years or older, completed the pilot instrument of 45 bipolar adjective scales. A principal components factor analysis revealed 20 scales that loaded on one dominant factor; this factor accounted for 60% of the variance for the 20 scales. Cronbach alpha reliability was .96. The revised 20-scale instrument was called the Menopause Attitude Scale (MAS). A second sample of 419 women completed the MAS and one additional instrument for assessment of convergent and discriminant validity. Convergent validity was demonstrated by a correlation of r = .63 for the MAS with the Attitudes Toward Menopause Scale. Discriminant validity was demonstrated by a correlation of r = .42 for the MAS with the Attitudes Toward Old People Scale and a correlation of r = -.04 for the MAS with the Attitudes Toward Women Scale. Factor analysis of MAS scores revealed that one factor accounted for 61.5% of the variance for the 20 scales. The test-retest reliability for 39 subjects was .87. Multiple regression analysis identified age and menopausal status as significant explanatory variables for MAS scores.

Adolescent↗