Biomedical subjects
P Webb
Publications and source records attributed to P Webb.
Analysis of regulatory sequences in androgen-responsive genes.
We have analysed the effect of androgens on the activity of promoters from MMTV, and the rat prostate C3(1) and mouse secretory protease inhibitor genes. MMTV promoter activity was stimulated by testosterone as well as progesterone and dexamethasone but not by oestradiol. Deletion analysis indicated that the three steroids acted through DNA sequences between nucleotides -201 and -69 upstream of the MMTV cap site. In contrast, the promoters for the C3(1) gene and the protease inhibitor gene were unaffected by testosterone in a number of cell types, including prostate cells, despite the fact that the MMTV promoter was stimulated in such cells.
The work of walking: a calorimetric study.
Experiments were designed to test the traditional assumption that during level walking all of the energy from oxidation of fuel appears as heat and no work is done. Work is force expressed through distance, or energy transferred from a man to the environment, but not as heat. While wearing a suit calorimeter in a respiration chamber, five women and five men walked for 70 to 90 min on a level treadmill at 2.5, 4.6, and 6.7 km.h-1 and pedalled a cycle ergometer for 70 to 90 min against 53 and 92 W loads. They also walked with a weighted backpack and against a horizontal load. During cycling, energy from fuel matched heat loss plus the power measured by the ergometer. During walking, however, energy from fuel exceeded that which appeared as heat, meaning that work was done. The power increased with walking speed; values were 14, 29, and 63 W, which represented 11, 12, and 13% of the incremental cost of fuel above the resting level. Vertical and horizontal loads increased the fuel cost and heat loss of walking but did not alter the power output. This work energy did not re-appear as thermal energy during 18 h of recovery. The most likely explanation of the work done is in the inter-action between the foot and the ground, such as compressing the heel of the shoe and bending the sole. We conclude that work is done in level walking.
Mapping cis-DNA regulatory elements in seminal vesicle secretion genes, prostate C3(1) gene, and the mouse mammary tumor virus-long terminal repeat DNA.
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Energy expenditure over 24 hours, thermal comfort and fat-free mass in Asian men.
Energy expenditure while sitting or sleeping was measured over 24 h in eight young Asian immigrants to France by a suit calorimeter and also by continuous measurement of respiratory gas exchange. Fat-free mass (FFM) was estimated from skinfold measurements. The energy intake per kilogram FFM of the Asians was similar to a group of well-off North Americans of larger body size but similar body composition who had been the subjects of an earlier study. In both groups thermoneutrality was controlled by adjusting the circulating water temperature of the suit calorimeter according to the subjects' preferences. The hourly energy expenditure/kg FFM was 1.2 kcal during sleep and 1.7 kcal while sitting. The mean energy expenditure/kg FFM during a quiet day was 37 kcal/d or 1.5 kcal/h. Using published equations, the estimated BMR was 1490 kcal (6.2 MJ). This estimated value agrees quite well with the BMRs of these subjects as previously determined. In the metabolic room the daily sedentary energy expenditure averaged 1.15 BMR and the energy intake averaged 1.26 BMR for the study subjects in free-living conditions in an urban environment. This is below the 1.4 X BMR currently recommended as a 'minimum' energy intake for subjects of low activity.
Identification of androgen response elements in mouse mammary tumour virus and the rat prostate C3 gene.
The effect of steroid hormones on mouse mammary tumour virus (MMTV) promoter activity has been analysed in the breast cancer cell lines ZR-75-1 and T-47D 11. Both androgens and progestins were stimulatory in both cell lines, whereas glucocorticoids were stimulatory in only ZR-75 cells. A glucocorticoid response was restored to T-47D cells by the transient expression of a glucocorticoid receptor expression vector, suggesting that endogenous receptors were limiting. The effect of androgen was mediated by a region of MMTV previously shown to be essential for glucocorticoid and progestin responses between nucleotides -201 and -69 upstream of the cap site. Similarly, the effect of androgens on the rat prostate C3(1) gene promoter was analysed in the rat prostate cell line T5. Although these cells had functional androgen receptors which could stimulate MMTV-promoter activity, they were incapable of interacting with androgen response elements to stimulate transcription from the C3(1) promoter.
Fish oil increases peripheral capillary blood cell velocity in humans.
Fish oils containing n-3 fatty acids have been shown in humans to decrease platelet aggregation in vitro, lower plasma triglycerides, and to increase bleeding time. The in vivo effects of fish oils on microcirculatory blood flow in humans has not been studied to date. Twenty-one male subjects were randomly assigned to either olive oil (n = 10) or fish oil (n = 11) supplemented groups to determine the effects of these oils on capillary blood flow velocity (CBV) in the nailfold area. The subjects were given the oils for three weeks (1.5 g oil/10 kg b.wt./day) in a single blind study design. In addition to CBV plasma lipid profiles, blood viscosity, blood pressure and platelet and erythrocyte fatty acids were also determined prior to and after the dietary intervention. Fish oil supplementation significantly increased CBV, by 1.75-fold (0.144 +/- 0.069 to 0.253 +/- 0.147 mm/s). The olive oil group remained unchanged. Increased levels of n-3 fatty acids were noted in platelets and erythrocytes of the fish compared to olive oil-supplemented groups. Blood viscosity was unaltered in both groups, however, blood pressure in the olive oil supplemented group was significantly decreased. Plasma triglycerides were significantly decreased in the fish oil supplemented group. These observations suggest that increases in CBV after fish oil supplementation are due to changes in vascular tone and not to alterations in blood pressure or blood viscosity.
24-hour energy expenditure and the menstrual cycle.
To determine whether 24-h energy expenditure changes during the menstrual cycle, 10 normally menstruating women in their 20s and 40s were measured repeatedly for periods of 36 and 46 h by simultaneous direct and indirect calorimetry. A standardized sedentary daily schedule included three meals to provide food intake equal to expenditure. Eight of the 10 women showed increases of 8-16% during the 14-day luteal phase following ovulation, a significant increase (p less than 0.00002 by direct calorimetry, p less than 0.001 by indirect calorimetry). One subjects, whose increase was 14% following ovulation, showed no significant change during a month when she took an oral contraceptive. Progesterone from the corpus luteum is the likely cause of a 9% increase in 24-h energy expenditure in normally menstruating women.
Afterdrop of body temperature during rewarming: an alternative explanation.
Afterdrop, the continued fall of deep body temperatures during rewarming after hypothermia, is thought to endanger the heart by further cooling from cold blood presumed to be returning from the periphery. However, afterdrop is not always observed, depending on the circumstances. To explore this phenomenon, mild hypothermia was induced quantitatively with a suit calorimeter, using several patterns of cooling and rewarming. When cooling was rapid and followed immediately by rewarming, there were typical afterdrops in the temperatures measured in the rectum, auditory canal, and esophagus. However, when rewarming was delayed, or when cooling had been slow and prolonged, afterdrop was not seen. Afterdrops were then observed in two physical models that had no circulation: a bag of gelatin and a leg of beef. Central layers continued to give up heat as long as the surrounding layer was cooler. These results, together with recent findings by others that peripheral blood flow is low until afterdrop is complete, make this circulatory explanation of afterdrop improbable. Alternatively, afterdrop can be explained by the way heat moves through a mass of tissue.
Paired cisternae of endoplasmic reticulum in developing ovarian oocytes of the golden hamster.
Paired cisternae of rough endoplasmic reticulum linked together by two parallel structures exhibiting periodic striations have been observed in the cytoplasm of small pre-antrum oocytes in the golden hamster. They are present only in oocytes from animals older than 3 weeks of age. Two or more such pairs may be associated with one another, and similar structures have been observed in contact with the nuclear envelope. The peak incidence of the paired membranes coincides with a sharp increase in rough endoplasmic reticulum as the oocyte commences rapid growth. A suggested role for the paired membranes in production of new endoplasmic reticulum is discussed.
Metabolizable energy of human mixed diets.
Nine subjects (four women and five men) consumed the energy required to maintain body weight for 3 weeks (control) and 1000 kcal per day less than the energy required to maintain body weight for 6 weeks (undereating). Ordinary foods were used to provide a mixed diet which was standardized as to composition and analysed by bomb calorimetry and by proximate analysis. During the third week of the control period and the third and sixth weeks of the undereating period, food, faecal and urine samples were collected for calculations of the metabolizable energy of the diets. The mean coefficients of availability of the three energy nutrients were lower than predicted by the Atwater method, between 83.8 and 88.3 for protein, between 91.6 and 93.2 for fat and between 92.5 and 94.7 for carbohydrates. The calorie to nitrogen ratio of the urine of these subjects during the balance periods varied from 4.96 to 19.05. The metabolizable energy of these mixed diets was 12 to 24 per cent less than the energy calculated from US food tables. Formulas proposed to calculate the metabolizable energy of diets differed from our analysed metabolizable energies by 6.4 per cent (Miller & Payne, 1959), 6.8 per cent (Southgate, 1975) and 0.7 per cent (Miller & Judd, 1984).
Direct calorimetry and the energetics of exercise and weight loss.
Laboratory studies using direct calorimetry, a technique which is no longer either rare or difficult, have shown no essential differences between men and women who gain weight easily and the always lean. Both groups gained weight similarly when overeating by 1,000 kcal X d-1. Thermogenic responses to eating and the energy losses in food and urine were similar in the overweight and lean. Daily sedentary energy expenditure is a function of fat-free mass, and fat-free mass increases with obesity. During exercise, calorimetry has shown that heat losses are not always exactly matched to heat production as calculated from respiratory gas exchange, but a 24-h exercise period with a cycle ergometer showed reasonable energy balance when subjects ate as much as they spent. During weight loss from restricting food intake by 1,000 kcal X d-1, calorimetry showed a 12% reduction in sedentary energy expenditure. Based on calorimetry studies and other evidence in the literature, exercise increases energy expenditure, it may eliminate the reduced energy expenditure of caloric restriction, and it can increase muscle mass and thus increase both fat-free mass and daily expenditure.
Segmental aplasia and hydrometra in a goat.
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Oncology nursing. 2. Getting to the heart of cancer.
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Getting it right--patient teaching.
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Calorimetric evaluation of the diary-respirometer technique for the field measurement of the 24-hour energy expenditure.
The results of measuring the 24-h energy expenditure by the diary-respirometer technique (factorial method) have been compared to those obtained by direct measurement of heat output and continuous recording of oxygen consumption and carbon dioxide production. Anthropometric and skinfold measurements were used to estimate lean body mass in eight male Asian subjects. They remained for 36 h in a metabolic chamber wearing a calorimeter suit. A ventilated hood and differential gas analysers were used to measure oxygen consumption and carbon dioxide production. While the subjects were sitting inactive, the KM respirometer indicated a mean energy expenditure which was significantly lower than with the calorimeter suit or with the ventilated hood. During exercise on an ergometer at 25 W and 75 W the respirometer gave readings of energy expenditure which were also significantly lower than either the ventilated hood or the calorimeter suit. The daily energy expenditure expressed in MJ for a standard body weight of 60 kg (MJ/60 kg) measured from the calorimeter suit was 9.79 MJ; from the ventilated hood, 9.51 MJ; from the diary-respirometer method, 8.30 MJ. The mean energy intake, measured for 10 consecutive d after the the subjects had left the metabolic room was 7.87 MJ, while during their stay in the metabolic room, their spontaneous intake was 7.74 MJ. The diary-respirometer technique tends to cumulate the errors from an incorrect time and motion recording and the potential lack of representativeness of the measurement of the energy cost of the activities. In the present study, it seems that the discrepancy observed between the results of the different methods can be attributed almost entirely to the underestimation of the energy cost of the activities by the respirometer. Contrary to our expectation the diary-respirometer technique does not seem to overestimate systematically the daily energy expenditure.
The exchange of matter and energy in lean and overweight men and women: a calorimetric study of overeating, balanced intake and undereating.
In this study of overeating and undereating, the terms in energy exchange were measured by 24-h direct and indirect calorimetry, bomb calorimetry of food and feces, and changes in body weight and composition; on average, the terms balanced to within 200 to 300 kcal/day. All subjects, whether habitually lean or overweight, gained weight similarly during overeating and lost similarly during undereating. Nor was there any difference in the adaptive thermogenesis of overweight and lean men and women.