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Biomedical subjects

D Thompson

Publications and source records attributed to D Thompson.

At least 361 records · Page 20Linked to original sources
PubMed1988

Linear relationship between VO2max and VO2max decrement during exposure to acute hypoxia.

The purpose of these experiments is to test the hypothesis that exercise-induced hypoxemia at sea level in highly trained athletes might be exacerbated during acute hypoxia and therefore result in correspondingly larger decrements in maximal O2 uptake (VO2max) compared with less trained individuals. Thirteen healthy male volunteers were divided into two groups according to their level of fitness: 1) trained endurance athletes (T) (n = 7), with a VO2max range of 56-75 ml.kg-1.min-1 and 2) untrained individuals (UT) (n = 6), with a VO2max range of 33-49 ml.kg-1.min-1. Subjects performed two incremental cycle ergometry tests to determine VO2max under hypoxic conditions [14% O2-86% N2, barometric pressure (PB) = 760 Torr] and normoxic conditions (21% O2-79% N2, PB = 760 Torr). Tests were single blind, randomly administered, and separated by at least 72 h. Mean percent oxyhemoglobin saturation (%SaO2) during maximal exercise under hypoxic conditions was significantly (P less than 0.05) lower in the T group (77%) compared with the UT group (86%). Furthermore, the T group exhibited larger decrements (P less than 0.05) in VO2max (normoxic-hypoxic) compared with the UT group. Finally, a significant linear correlation (r = 0.94) existed between normoxic VO2max (ml.kg-1.min-1) and delta VO2max (normoxic-hypoxic). These data suggest that highly T endurance athletes suffer more severe gas exchange impairments during acute exposure to hypoxia than UT individuals, and this may explain a portion of the observed variance in delta VO2max among individuals during acute altitude or hypoxia exposure.

Acclimatization↗
PubMed1987

Characterization of a human osteosarcoma cell line (Saos-2) with osteoblastic properties.

This study examines the osteoblastic properties of the established human osteosarcoma cell line Saos-2. Saos-2 cells inoculated into diffusion chambers, which were implanted i.p. into nude mice, produced mineralized matrix in 4 of 6 chambers at 8 weeks. In 5 of 6 chambers there was a strong positive alkaline phosphatase reaction. In culture the alkaline phosphatase levels increased with time and cell density, reaching very high levels at confluence: 4-7 mumol/mg protein/min. The cells show a sensitive adenylate cyclase response to parathyroid hormone, 50% effective dose = 2.8 nM, which increases with cell density and is further raised by dexamethasone treatment. They also exhibit typical binding of 1-25-dihydroxyvitamin D3 to 3.2S receptor protein with an apparent Kd of 0.21 nM; the numbers of sites per cell were 3,300 at 50,000 cells/cm2 and 1,800 at 280,000 cells/cm2. The presence of osteonectin was visualized with a monoclonal antibody which revealed a reticular pattern on the cell surface. Osteonectin was also detected in the medium by Western blots, migrating at around Mr 40,000 in nonreduced gels and Mr 44,000 in reduced gels. The Saos-2 cells thus possess several osteoblastic features and could be useful as a permanent line of human osteoblast-like cells and as a source of bone-related molecules.

Adenylyl Cyclases↗
PubMed1987

Oxygen deficit-oxygen debt relationships in ponies during submaximal treadmill exercise.

The O2 deficit-O2 debt relationship in ponies was examined at two levels of treadmill exercise. Five healthy ponies exercised for 8 min at two work rates (WR):(1) 50 m/min at 6% grade and (2) 70 m/min at 12% grade. The O2 deficit and O2 debt were calculated using open-circuit measurement of pulmonary gas exchange during the transition from rest to steady-state exercise and during recovery from exercise. The O2 deficit was significantly lower (P less than 0.05) than the O2 debt at each of the two work rates. The means (+/- SEM) for the deficit and the O2 debt, respectively, in liters were: (1) low WR = 0.45 +/- 0.12; 0.92 +/- 0.13; high WR = 1.03 +/- 0.20; 1.62 +/- 0.12. Given the observation that the O2 deficit and the O2 debt are generally equal in humans during exercise below the anaerobic threshold, these findings suggest a species difference in the O2 deficit-O2 debt relationship. It is hypothesized that the difference in O2 deficit between man and pony is related to faster VO2 kinetics for the on-transient of exercise which involves a more rapid increase in cardiac output coupled with a release of splenic stored erythrocytes.

Animals↗
PubMed1987

Coalitions and conflict in the National Health Service: some implications for general management.

This paper suggests that conflict is an inescapable feature of National Health Service organisational life, and that it is legitimate area of study. It describes a number of powerful coalitions whose interactions can produce conflict as they attempt to influence the distribution of scarce resources. In particular, it focuses on the beliefs and power of a 'practitioner interests' coalition and an 'administrative ethic' coalition. To survive in this world of coalitions, NHS general managers need to assert their own positions. Are they to be agents of the existing coalitions or can they construct their own and achieve its dominance? The paper concludes by discussing how a distinctive general management coalition might emerge.

Conflict, Psychological↗
PubMed1987

Ehlers-Danlos syndrome: yet another type?

A mother and her four children had gross generalized joint laxity, with multiple dislocations and subluxations, moderate skin hyperextensibility and mild connective tissue fragility. Their condition could be categorized in the Ehlers-Danlos syndrome Type III or the familial undifferentiated hypermobility group of disorders, but differed from these conditions by virtue of the severity of articular complications and the presence of wormian bones in the skulls. We consider that these patients have an undelineated connective tissue disorder; attempts at characterization at the molecular level are underway.

Adult↗
PubMed1987

Midtrimester genetic amniocentesis in eastern Ontario: a review from 1970 to 1985.

Greater use of genetic amniocentesis in the Eastern Ontario region occurred once the results from the various national trials were published. Acceptance also paralleled an increase in the number of low parity older women having children and the centralisation and greater publicity given to our programme in the late 1970s. A centralised approach has had the positive effects of preventing unnecessary procedures, assuring appropriate patient counselling, follow up, and review, and of increasing obstetric and laboratory expertise. Advanced maternal age has been largely responsible for the increased demand for the service and accounted for an increasing proportion of tests performed, while the absolute number for several other diagnostic categories remained unchanged. We found no evidence that women with a history of previous miscarriage had a higher rate of pregnancy loss following the procedure, and comparison with a group of women who declined amniocentesis did not show that the test increased the risk of miscarriage.

Abortion, Spontaneous↗
PubMed1987

Ventilatory and blood gas dynamics at onset and offset of exercise in the pony.

The purpose of these experiments was to examine the temporal pattern of arterial carbon dioxide tension (PaCO2) to assess the relationship between alveolar ventilation (VA) and CO2 return to the lung at the onset and offset of submaximal treadmill exercise. Five healthy ponies exercised for 8 min at two work rates: 50 m/min 6% grade and 70 m/min 12% grade. PaCO2 decreased (P less than 0.05) below resting values within 1 min after commencement of exercise at both work rates and reached a nadir at 90 s. PaCO2 decreased maximally by 2.5 and 3.5 Torr at the low and moderate rate, respectively. After the nadir, PaCO2 increased across time during both work rates and reached values that were not significantly different (P greater than 0.05) from rest at minute 4 of exercise. Partial pressure of O2 in arterial blood and arterial pH reflected hyperventilation during the first 3 min of exercise. At the termination of exercise PaCO2 increased (1.5 Torr) above rest (P less than 0.05), reaching a zenith at 2-3 min of recovery. These data suggest that VA and CO2 flow to the lung are not tightly matched at the onset and offset of exercise in the pony and thus challenges the traditional concept of blood gas homeostasis during muscular exercise.

Animals↗
PubMed1987

Effects of vitamin A deficiency and repletion on rat insulin secretion in vivo and in vitro from isolated islets.

We studied the effects of vitamin A deficiency and repletion on rat insulin release and islet cellular retinol binding protein (CRBP) and cellular retinoic acid binding protein (CRABP). Biphasic insulin release from vitamin A-deficient perifused islets was markedly impaired. Release remained impaired with retinoic acid (RA) repletion, 2 micrograms/g diet compared to release from islets of rats repleted with retinol in the form of retinyl palmitate, 4 micrograms/g diet. Release normalized with RA, 8 micrograms/g diet. Vitamin A deficiency did not affect islet insulin content, cell size, number or structure. In vivo, vitamin A-deficient rats had impaired glucose-induced acute insulin release and glucose intolerance, which improved with repletion. Normal islets had greater concentrations of CRBP than CRABP; vitamin A deficiency reduced CRBP but not CRABP levels. We conclude retinol is required for normal insulin secretion. Retinoic acid may substitute for retinol in this function.

Animals↗
PubMed1987

Pyloric exclusion. Suture material of choice.

Pyloric exclusion was first reported in 1977 as a temporary method of providing duodenal decompression in an attempt to protect the duodenum in the early postoperative period during the healing phase, followed by the return of normal gastrointestinal transit. It has been adopted by several trauma centers across the country as part of their armamentarium for managing moderate to severe duodenal injuries. Most series report using a polyglycolic acid (PGA) suture in performing the exclusion, anticipating a 3- to 4-week interval before pyloric patency is re-established. A comparison of polypropylene (PP), polyglycolic acid (PGA), and polydioxanone (PDS) sutures in the dog model suggests, however, that only PDS reliably accomplishes this goal. The low (approximately 5-10%) but finite incidence of fistula formation reported with pyloric exclusion using PGA may be improved by using PDS instead.

Animals↗
PubMed1987

Measurement of oxygen uptake in the non-steady-state.

The purpose of these experiments was to develop and validate an open-circuit technique for measurement of gas exchange during the transition from rest to constant load steady-state exercise. The design of the open-circuit system employed to measure gas exchange in these experiments used a mixing chamber to collect the subject's expired ventilation where fractions of O2 and CO2 were determined via electronic gas analyzers. A gasometer was used to measure inspired ventilation and the analog signals from the two gas analyzers and the gasometer were sent to a microcomputer for computation of VO2. In calculating VO2, the mixed expired gas concentrations were matched with ventilatory volume using a previously determined time delay. To determine the validity of the open-circuit system, four subjects performed a series of 16 rest-to-work transitions on a cycle ergometer. In eight of the experiments, serial measurements of VO2 were obtained every 20 s for 3 min using the open-circuit mixing chamber system while the additional eight experiments used the Douglas bag technique. No significant difference (p greater than 0.05) existed between VO2 values calculated by the two techniques. Mean differences in VO2 between the two techniques during the first three 20-s measurement periods were 6, 53, and 63 ml, respectively. Using the Douglas bag technique as the standard, this represents a relative measurement error of 0.1%, 4.5%, and 3.6%, respectively, at the above time intervals. These data demonstrate that an open-circuit system employing a mixing chamber and the appropriate time delay to match expired gas fractions and ventilation is a sensitive means of measurement of VO2 in the non-steady-state.

Breath Tests↗
PubMed1987

Protection from radiation enteritis by an absorbable polyglycolic acid mesh sling.

Patients with malignant tumors of the pelvis who cannot be cured surgically often are treated with radiation after surgery. A devastating side effect of this treatment is radiation-associated small bowel injury (RASBI). The purpose of this study was to test the hypothesis that removal of the small bowel from the radiation field would protect it against RASBI. Twenty cebus monkeys underwent low anterior resection. In 10 animals an absorbable polyglycolic acid (PGA) mesh was sewn circumferentially around the interior of the abdominal cavity as a supporting apron, which prevented the small bowel's descent into the pelvis. The other 10 monkeys did not receive the mesh. All animals received 2000 rads by linear acceleration in a single dose. Twenty-four-hour stool fat, serum vitamin B12, and other serum values were obtained during the study. Animals were sacrificed after 1, 2, 3, 6, and 12 months, and the small bowel and rectum were examined histologically in a blind manner. Two monkeys who did not undergo surgery, or exposure to radiation served as controls. At all sacrifice periods, the animals with PGA mesh slings demonstrated normal small bowel function and histologic structure. Animals without mesh slings had abnormal stool and blood values at 1 month, and by 2 months all had died of small bowel necrosis. The animals that received the slings had no evidence of infection or obstruction, and by 6 months all evidence of the mesh was gone. Support of the small bowel out of the pelvis by an absorbable PGA mesh sling protects against RASBI and is without apparent complications.

Animals↗
PubMed1986

A survey of Campylobacter and other bacterial contaminants of pre-market chicken and retail poultry and meats, King County, Washington.

As part of a larger study to determine the flow of Campylobacter and Salmonella from food animals to humans during 1982-83, 1,936 swabs were collected for bacteriologic study from pre-market chickens, retail poultry, and other retail meats as well as from equipment and work surfaces used to process such foods. Of the 297 samples collected in a poultry processing plant, 56.6 per cent were positive for Campylobacter jejuni/coli (CJC), as were 23.1 per cent of the 862 retail chicken, and 17.2 per cent of the 29 retail game hen samples. CJC was found infrequently in retail turkey, pork, and beef samples. Contamination of retail and pre-market chicken with CJC appeared to increase as the week progressed, and in pre-market chicken, later in the day. Less than 5 per cent of the retail samples of poultry, beef, and pork were found to contain Yersinia or Salmonella. However, Salmonella was cultured from 14.8 per cent of the swabs taken from the processing plant with 68 per cent of 44 Salmonellas being isolated concurrently with CJC. Tetracycline resistance which was plasmid-mediated was the most common antibiotic resistance observed, and was carried by 23.8 per cent of all CJC isolates. Overall, 38.8 per cent of all CJC isolates were resistant to ampicillin, erythromycin, streptomycin, or tetracycline, either singly or in combination.

Animals↗