Search PubMed⌕ Search

Biomedical subjects

R Whitehead

Publications and source records attributed to R Whitehead.

At least 37 records · Page 2Linked to original sources
PubMed1992

Postprandial thermogenesis in lactating and non-lactating women from The Gambia.

Postprandial thermogenesis was assessed by indirect calorimetry in 32 Gambian women classified into three groups as follows: 12 non-pregnant non-lactating and 10 lactating women studied during the dry season and 10 lactating women studied during the rainy season. The test meal consisted of a typical Gambian breakfast and its energy content corresponded to 30% of the individual's resting metabolic rate (RMR)/24 h. During the dry season, the postprandial thermogenesis of the lactating women averaged 6.0 +/- 0.4% of the test meal energy content and was similar to that observed in the non-pregnant non-lactating women studied during the same season (5.8 +/- 0.3%). In contrast, the postprandial thermogenesis of lactating women studied during the rainy, nutritionally unfavourable season was found to be significantly lower (4.9 +/- 0.5%). There was no significant difference in the pre- and postprandial respiratory quotients among groups. This leads to the conclusion that lactation does not alter the thermogenic response to food and that the reduction in postprandial thermogenesis observed in lactating women during the wet season constitutes an adaptive response to energy deficit allowing a saving of energy in periods of food restriction.

Adolescent↗
PubMed1991

Seasonal changes in 24-h and basal energy expenditures in rural Gambian men as measured in a respiration chamber.

Adaptation of 24-h energy expenditure (24-h EE) to seasonal variations in food availability was studied, by using a respiration chamber, in 18 rural Gambian men on three occasions: period 1--at the end of the rainy season, which is characterized by low food availability; period 2--during the nutritionally favorable dry season; and period 3--at the onset of the following rainy season. From periods 1 to 2 body weight increased by 2.8 +/- 0.4 kg, and a rise in 24-h EE was observed (from 8556 +/- 212 kJ/d to 9166 +/- 224 kJ/d), which was correlated to weight change (r = 0.73, P less than 0.001). During period 3, 24-h EE averaged 8740 +/- 194 kJ/d. Diet-induced thermogenesis increased significantly from periods 1 to 2 (5.9 +/- 0.5% to 8.2 +/- 0.8%) and subsequently decreased to 3.6 +/- 0.6% during period 3. In rural Gambian men, metabolic adaptations in response to seasonal changes in food availability are reflected by a decrease in body weight, mainly manifested by a loss of fat-free mass accompanied by a decreased 24-h EE and a lowered diet-induced thermogenesis.

Adult↗
PubMed1991

A new procedure to assess the energy requirements of lactation in Gambian women.

The combined 24-h energy expenditure (24-h EE) of mother and child was measured with a respiratory chamber (indirect calorimeter) in a group of 16 lactating Gambian women and was compared with that of a control group of 16 nonpregnant, nonlactating (NPNL) Gambian women. Breast-milk production (738 +/- 47 g/d: mean +/- SE) was adequate to allow a normal rate of growth of their 2-mo-old babies (28.0 +/- 2.4 g/d). The combined 24-h EE (mother and child) was higher (8381 +/- 180 kJ/d. P less than 0.001) than that of NPNL women (6092 +/- 121 kJ/d). Two-thirds of this differences could be attributed to the child's EE and one-third to a greater spontaneous physical activity of lactating women. The energy retained by the child for growth in conjunction with the calorimetric measurements allowed the calculation of the extra energy requirements for lactation, which were found to be 2100 kJ/d. These results confirm the values of the current dietary recommendations for lactation, based on the energy cost of milk production.

Adult↗
PubMed1991

Stimulation by human chorionic gonadotropin of prostaglandin synthesis by early human placental tissue.

Successful establishment of pregnancy is dependent on inhibition of clotting and suppression of the maternal immune response at the feto-maternal interface. Early human placental production of prostacyclin (PGI2) and prostaglandin E2 (PGE2) may be important in this process. To examine the possible role of these PGs, we studied PGE and 6-keto-PGF1 alpha (stable metabolite of PGI2) synthesis in human placental (9-17 weeks gestation) organ cultures, and monolayer cultures of purified trophoblasts. PGE2 appeared to be the major protanoid formed. Other arachidonic acid metabolites identified in placental organ culture were 6-keto-PGF1 alpha, thromboxane B2, PGF2 alpha, leukotriene B4, 5(S)-hydroxyeicosatetraenoic acid (5-HETE), 12-HETE, and 15-HETE. The synthesis of PGE and 6-keto-PGF1 alpha altered with gestation and was maximal in the younger placentas. Arachidonic acid (33 microM) stimulated and indomethacin (28 microM) inhibited PG production. hCG, including physiological concentrations, stimulated PGE and 6-keto-PGF1 alpha synthesis in placental organ cultures. This effect was most striking in the 9-12 week placentas, compared to 15-17 week placentas. A similar hCG-induced stimulation of PGE production occurred in monolayer cultures of trophoblasts. The addition of TSH, FSH, and LH indicated that this effect was specific for hCG. These data suggest that hCG may have a biological role in the regulation of PG synthesis in early human placenta.

6-Ketoprostaglandin F1 alpha↗
PubMed1991

Is human lactation a particularly efficient process?

The recommended dietary allowances of many expert committees (UK DHSS 1979, FAO/WHO/UNU 1985, USA NRC 1989) have set out the extra energy requirements necessary to support lactation on the basis of an efficiency of 80 per cent for human milk production. The metabolic efficiency of milk synthesis can be derived from the measurements of resting energy expenditure in lactating women and in a matched control group of non-pregnant non-lactating women. The results of the present study in Gambian women, as well as a review of human studies on energy expenditure during lactation performed in different countries, suggest an efficiency of human milk synthesis greater than the value currently used by expert committees. We propose that an average figure of 95 per cent would be more appropriate to calculate the energy cost of human lactation.

Adult↗
PubMed1990

Twenty-four-hour energy expenditure and basal metabolic rate measured in a whole-body indirect calorimeter in Gambian men.

By use of a respiration chamber, 24-hour energy expenditure (EE), diet-induced thermogenesis (DIT), and basal and sleeping EE were measured in 20 young rural Gambian men during the "hungry" season (weight, 60.8 +/- 1.4 kg) and in a group of 16 European men matched for body composition (weight, 66.9 +/- 1.9 kg). The 24-h EE was lower in Gambian than in European men (2047 +/- 46 vs 2635 +/- 74 kcal/d, p less than 0.001, respectively). Basal EE and sleeping EE were also lower in Gambian than in European men (1.05 +/- 0.02 vs 1.25 +/- 0.02 kcal/min and 1.0 +/- 0.02 vs 1.18 +/- 0.02 kcal/min, p less than 0.01, respectively). DIT was blunted in Gambian compared with European men (6.3 +/- 0.6% vs 12.1 +/- 0.5%, p less than 0.001 respectively). The net efficiency of walking was greater in Gambian than in European men (23.2 +/- 0.3% vs 20.1 +/- 0.4%, p less than 0.001, respectively). A low basal and sleeping EE, a reduced DIT, and a high work efficiency are important energy-sparing mechanisms in Gambian men, which allow them to cope with a marginal level of dietary intake during the hungry season.

Adult↗
PubMed1989

Morphometric analysis of nuclear features, ploidy status, and staging in rectal carcinoma.

Recently, several flow cytometric studies have shown that the nuclear DNA content in colorectal carcinoma gives prognostic information which is independent of that provided by the histological characteristics of the tumour. In this study the nuclear DNA content and nuclear morphology of 39 cases of surgically resected rectal adenocarcinoma were measured in Feulgen-stained histological sections by video image analysis and 97 per cent were aneuploid. Dukes' stage correlated better with the morphometric data than did other classification systems. The extent of local spread and the growth pattern at the invasive margin of the tumour, which are of known prognostic importance, were significantly related to some nuclear features. Discriminant analysis of the nuclear morphometric data alone was highly successful in predicting these tumour characteristics. The results suggest that routine application of this technique to tumour biopsies may be of value in patient management since it provides stage-related information which cannot be obtained by conventional histopathological assessment.

Adenocarcinoma↗
PubMed1989

Cephalometric and cineradiographic study of deviant resonance in hearing-impaired speakers.

To study physiological basis for deviant resonance in hearing-impaired speakers, cephalometric roentgenography and cineradiography were applied to analyze oral/pharyngeal relationships during vowels produced in isolation and within a sentence context. The films, synchronized with sound recording, were traced and measured for 10 normal hearing and 4 hearing-impaired women with deviant resonance. Vocal tract conformations and dimensions were defined by measures of the lips, tongue, mandible, velum, hyoid bone, epiglottis, and laryngeal sinus. Means, standard deviations, and analyses of variance were applied to facilitate descriptions and comparisons between the groups. The hearing-impaired speakers had near normal lip openings for /i/ and /u/ but more open positions for /a/. The tongue tended to retract for the front vowel and front for the back vowel /u/. For high vowels, most of the hearing-impaired speakers had an elevated hyoid, an unusually large vertical dimension between hyoid and laryngeal sinus, and a retracted tongue root, which was associated with a marked retraction or deflection of the epiglottis toward the pharyngeal wall. The cine analysis of the normal hearing speakers showed rather well defined and consistent shifts in tongue position for the front vowels produced in the sentence context. The hearing-impaired speakers with deviant resonance showed greater variation among speakers in tongue body position and a significant retrusion of the dorsum of the tongue at a site significantly lower than observed in hearing speakers. The consistent tongue root retraction during static as well as dynamic speech production is interpreted as support for Boone's hypothesized cause of pharyngeal resonance in speech of the hearing impaired.

Adult↗
PubMed1988

Campylobacter-like organisms and Candida in peptic ulcers and similar lesions of the upper gastrointestinal tract: a study of 247 cases.

Campylobacter-like organisms were detected by light microscopy in association with 57 of 102 (56%) of gastric ulcers, all the gastric erosions associated with gastritis, three of five (60%) of gastric erosions without gastritis, five of 13 (39%) of mild superficial gastritis and two of 36 (6%) of normal gastric mucosa. They were also seen in four of 20 (20%) of duodenal ulcers, but not in duodenal erosions with duodenitis or normal duodenal biopsy specimens. They were seen in association with 12 of 64 (19%) of cases of Barrett's oesophagus. Moniliasis was seen in nine of 78 (12%) of the gastric ulcers in which campylobacter-like organisms were found, and the incidence of moniliasis was three of 15 (20%) in association with duodenal ulcers when ulcer debris was present in biopsy material, and in association with six of 25 (24%) of cases of Barrett's oesophagus. These findings do not support the hypothesis that campylobacter-like organisms cause inflammatory and ulcerative lesions of the upper gastrointestinal tract.

Barrett Esophagus↗
PubMed1987

The morphogenesis of the human Paneth cell. An immunocytochemical ultrastructural study.

In human duodenal mucosa Paneth cells originate away from the base of crypts and migrate towards the base during maturation. The earliest cells in the Paneth cell lineage could be identified by labelling of lysozyme in the Golgi apparatus. Specific labelling for lysozyme was present in the rough endoplasmic reticulum, Golgi apparatus, condensing vacuoles, granules and many lysosomes of mature Paneth cells. The maturation of the Paneth cell is accompanied by an increase in the content of lysozyme in the secretory granules and with senescence lysozyme diffuses into the cytoplasm.

Cell Differentiation↗
PubMed1987

Correlation of nuclear ploidy with histology in adenomatous polyps of colon.

Histological sections of adenomatous polyps of the colon showing carcinoma were studied by video image analysis. Nuclear DNA content and morphology were measured in regions identified as either dysplasia, carcinoma confined to the mucosa, or carcinoma invading the muscularis mucosa. Where carcinoma was present, areas of dysplasia in the same polyp were found to have similar distributions of nuclear DNA content and size, supporting the notion that adenomatous polyps becomes cancer. The method can be used to detect those regions in sections of adenomatous polyps with the most severe nuclear abnormality.

Adenocarcinoma↗
PubMed1986

Non-carcinoid epithelial tumours of the appendix--a proposed classification.

Examination of 33 cases of non-carcinoid epithelial tumours of the appendix and a review of the previous literature has led us to propose a new classification of these lesions. It is based on nomenclature currently used for similar mucosal proliferations in the colon, facilitating communication between pathologists and clinicians with respect to their nature and possible behaviour. The use of the term "mucocele" to describe any lesion in which there is mucinous distension of the appendiceal lumen, irrespective of the type of underlying mucosal pathology, is now largely discredited. Yet, although a resemblance of some appendiceal lesions to similar lesions in the colon has been recognized, current terminology is still confused by the use of "cystadenoma". We have been able to place all of the known non-carcinoid appendiceal mucosal tumours into 4 main diagnostic categories, these being--adenoma, hyperplasia, mixed adenoma/hyperplasia and adenocarcinoma, and propose these terms as the basis for a new classification.

Adenocarcinoma↗
PubMed1986

Gastric hemorrhage due to ruptured arteriovenous malformation (Dieulafoy's disease).

Dieulafoy's disease is one of the less common causes of significant hematemesis and/or melena. It occurs most frequently in middle-aged and elderly males, but both sexes and all ages may be affected. Histopathologically the lesion found is variable but includes the classical single large tortuous artery as well as thin-walled venous anomalies, and mixtures of these two. We present 4 cases of this condition.

Adult↗