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Biomedical subjects

S Bartlett

Publications and source records attributed to S Bartlett.

At least 37 records · Page 2Linked to original sources
PubMed1993

Hexachlorobenzene toxicity in the monkey primordial germ cell without induced porphyria.

Hexachlorobenzene is a persistent chlorinated organic chemical that has been detected in many tissues from a variety of species including human ovary and human ovarian follicular fluid. When administered in high dosage to nonhuman primates, hexachlorobenzene causes destruction of ovarian primordial germ cells in association with systemic toxicity. The purpose of these experiments was to assess relative ovarian germ cell sensitivity at much lower dosages of hexachlorobenzene that do not produce systemic effects and additionally to evaluate oocyte function by means of the response to superovulation, fertilization, and embryo cleavage during a cycle of in vitro fertilization in the cynomolgus monkey. Hexachlorobenzene in dosages of 0.1, 1.0, and 10.0 mg/kg/day was administered orally by gelatin capsule for 90 days. There was a dose-dependent accumulation of HCB in serum and other tissues without any change in the serum estradiol response to human menopausal gonadotropin, oocyte recovery, oocyte maturation, oocyte fertilization in vitro, and early embryo cleavage rate. There was a dose-related toxic effect observed in primordial germ cells at the lowest dose despite no evidence of systemic or hepatic effects. As there were no changes in the urinary porphyrin excretion, the mechanism of hexachlorobenzene ovotoxicity may be distinct from hexachlorobenzene-induced cytochrome P-450-dependent inhibition of uroporphobilinogen decarboxylase in the liver, although such intraovarian metabolism cannot be excluded.

Animals↗
PubMed1992

Relationship of dieting history to resting metabolic rate, body composition, eating behavior, and subsequent weight loss.

This study examined the relationship of dieting history to resting metabolic rate, body composition, and subsequent weight loss in 50 obese women. A preliminary study showed that the women were able to report with satisfactory reliability the number of diets in which they had engaged (mean = 4.9 +/- 0.5), as well as the total weight loss resulting from these diets (mean = 55.9 +/- 6.0 kg). We found no evidence that weight cycling, as measured by either of these variables, was associated at baseline with a reduced resting metabolic rate or an increased percentage of body fat. Nor did we find that weight cycling was associated with smaller weight losses in a prospective trial in which subjects were treated by very-low-calorie diet and behavior therapy. The clinical implications of these findings are discussed, as are the methodological problems encountered in conducting research on this topic.

Adipose Tissue↗
PubMed1991

Protein metabolism after abdominal surgery: effect of 24-h extradural block with local anaesthetic.

We have studied the effect of intraoperative and postoperative (24 h) extradural block with local anaesthetic on whole body protein turnover (stable isotope methodology) and urinary excretion of urea nitrogen, adrenaline, noradrenaline and cortisol in a group of well nourished elderly patients undergoing colorectal surgery who received a constant nutritional intake before (7 days) and after (4 days) surgery. One group (control, n = 8) received routine anaesthetic and surgical care. Patients in the test group (extradural, n = 9) received extradural bupivacaine, and sensory block (T4-S5) was maintained during and after surgery for a period of 24 h. Whole body protein breakdown and amino acid oxidation increased significantly after surgery in both groups (P less than 0.05), but the increase in protein breakdown in the extradural group was significantly less than that in the control group. Urinary excretion of urea nitrogen, adrenaline and noradrenaline increased in the control group after surgery, whilst the increase in the extradural group was very small. In contrast, urinary excretion of cortisol increased significantly in both groups after surgery. We conclude that extradural block maintained for 24 h after surgery significantly minimized postoperative protein breakdown without compromising whole body protein synthesis.

Abdomen↗
PubMed1991

Childhood asthma and the indoor environment.

To investigate the influence of indoor air quality on respiratory health, a questionnaire-based study of 17,962 Canadian schoolchildren in kindergarten through grade 2 was carried out in 1988. The present report focuses on associations between several indoor environmental factors and childhood asthma. Increased reports of physician-diagnosed asthma were significantly associated (p less than 0.001) with exposure to environmental tobacco smoke (OR = 1.4), living in a damp home (OR = 1.5), the use of gas for cooking (OR = 2.0) and the use of a humidifier (OR = 1.7). Wheezing without a diagnosis of asthma also was associated (p less than 0.01) with environmental tobacco smoke (OR = 1.4, home dampness (OR = 1.6) and humidifier use (OR = 1.4), but not with gas cooking. Thus, several modifiable risk factors for respiratory illness may exist in Canadian homes. Further research is required to determine the nature of these cross-sectional observations.

Air Pollution, Indoor↗
PubMed1990

Chorioretinal folds and a macular hole secondary to craniofacial surgery.

Chorioretinal folds have been reported as a result of many intraocular and extraocular inflammatory processes or tumors. Visual loss is usually secondary to a combination of the underlying process and chorioretinal folds involving the macula. We report a patient who developed decreased vision, metamorphopsia, chorioretinal folds, and a lamellar macular hole secondary to global compression by a bone fragment. The chorioretinal folds regressed and his vision stabilized following surgical decompression. Chorioretinal folds and lamellar macular hold formation are previously unrecognized complications of reconstructive craniofacial surgery.

Adult↗
PubMed1989

Increased plasma carnitine in severe alcohol dependence.

Carnitine plays a central role in lipid metabolism. There have been several suggestions that carnitine metabolism is affected in alcoholism. In the present study plasma carnitine levels in severely dependent alcoholic patients were investigated. The results show that total and free plasma carnitine in 11 out of 14 patients were raised above those found in normal control subjects. This may be indicative of changes central to the disease process. We suggest that plasma free carnitine represents a useful test which can be added to those currently used to assess alcohol dependence.

Adult↗
PubMed1987

Staged use of soft-tissue expansion and lower thoracic advancement flap in breast reconstruction.

A single patient is presented in whom breast reconstruction after mastectomy for breast cancer has been achieved by sequential use of soft-tissue expansion followed by permanent silicone implant placement and thoracic flap advancement to define the inframammary fold. This procedure may play a useful role in patients in whom other, more complex methods of breast reconstruction are not selected or indicated and in particular in patients in whom bilateral silicone implants are utilized.

Adult↗
PubMed1985

Shape sensing for computer aided below-knee prosthetic socket design.

Shape sensing is useful in the computer aided prosthetic fitting process for two purposes. 1. To input characteristic prosthetic shapes that have been developed over the years through the experience of prosthetists. 2. To provide an accurate and rapid measurement of the anatomical shape of the stump. This paper describes two instruments which have been built to meet these objectives.

Amputation Stumps↗
PubMed1984

Strain differences among inbred mice in protein kinase C activity.

A protein kinase was identified in mouse organs whose activity is strictly dependent on the presence of Ca++ and phosphatidylserine when assayed at pH 6, and thus has the characteristics of protein kinase C. The relative order of specific activities was brain greater than spleen greater than lung greater than heart, an order similar to that found previously for rat organs. Mice from seven strains had the same level of protein kinase C activity, but strain A/J had half as much activity in each organ as did the other strains. F1 hybrid mice resulting from a cross between A/J and BALB/cByJ mice had levels of activity intermediate to the parental strains, indicating additive inheritance of this genetic difference.

Animals↗
PubMed1984

The influence of renal function on lactate and glucose metabolism.

The relationship of lactate metabolism to renal function was studied in the isolated perfused rat kidney. A new radioisotopic method has been developed that enables the simultaneous measurement of lactate production and consumption in the presence of physiological concentrations of both lactate and glucose. In kidneys from fed rats, when glucose was absent, lactate production was only 12 mumol/h per g dry wt, and in kidneys from starved rats there was no lactate production, indicating that neither the phosphoenolpyruvate/pyruvate substrate cycle nor other analogous cycles for the recycling of lactate carbon are operating in the intact kidney cortex. Lactate production from glucose occurred at a high rate, at the same time as lactate consumption, demonstrating that lactate recycling between renal cortex and medulla can occur in the intact kidney. Lactate production from glucose correlated with glomerular filtration rate (P less than 0.001), urine flow rate (P less than 0.01) and sodium reabsorption (P less than 0.05). There was significant basal lactate production at zero glomerular filtration rate. Lactate consumption was not correlated with any renal function. When Na+ reabsorption was inhibited with the diuretic frusemide, or when filtration was entirely prevented (the 'non'-filtering kidney'), lactate production was decreased by 39% and 50% respectively. Basal lactate production determined in this way was the same as that calculated above by linear regression. Prevention of filtration, but not the addition of frusemide, significantly inhibited lactate consumption. It is concluded that glycolysis is required for medullary Na+ transport, and that some different transport function(s) require lactate oxidation.

Animals↗
PubMed1984

Monitoring response to chemotherapy of intact human tumours by 31P nuclear magnetic resonance.

10 kidneys bearing adenocarcinoma (hypernephroma), 1 ureteric tumour, 2 Wilms' tumour from patients undergoing nephrectomy, and normal human and animal kidneys were preserved and later tested to see whether normothermic blood perfusion restored glomerular filtration, oxygen consumption, and energy metabolism, as monitored by 31P nuclear magnetic resonance (NMR). NMR spectra of normal human kidney and of renal tumours were characteristic of kidney in other species (rat, rabbit, and dog), with six principal resonances assigned to adenosine monophosphate, inorganic phosphate (Pi), glycerophosphoryl choline, gamma, alpha, and beta adenosine triphosphate and an intrarenal pH 7.0-7.2. 7 out of 9 hypernephromas and 1 of the 2 Wilms' tumours produced an additional resonance at +4.2 ppm. This peak was absent from all normal kidney spectra and may represent Pi in a specific and highly acidic environment (pH 6.1-6.5) found in actively metabolising human tumours. Furthermore, in 1 tumour (out of 5 tested) the +4.2 ppm peak rose rapidly after the addition of chemotherapeutic agents to the perfusing blood. This observation may indicate drug sensitivity of this one tumour. The results suggest that 31P NMR imaging may be used to monitor therapeutic response during regional perfusion of malignant tumours in man.

Animals↗
PubMed1984

Carnitine as a possible adjunct in parenteral feeding.

Carnitine is necessary for the transport of fatty acids across the inner mitochondrial membrane, and depletion in response to Intralipid infusion has previously been demonstrated. This study investigates whether orally administered L-carnitine increases tolerance to a lipid load given intravenously. Eight patients with active inflammatory bowel disease, being treated with intravenous prednisolone, were studied. Intralipid was infused on two occasions. Triglycerides and ketone bodies rose in a reproducible manner. Carnitine did not influence these changes. Carnitine excretion rose after an oral dose indicating that carnitine was absorbed, but carnitine excretion was increased in the steroid-treated individuals and rose after oral prednisolone in two healthy subjects. It is concluded that under the conditions of this study oral carnitine is without demonstrable effect on the handling of an intravenous lipid load.

Journal Article↗
PubMed1983

Energetics of sodium transport in the kidney. Saturation transfer 31P-NMR.

31P-NMR has been used to quantify inorganic phosphate (Pi) and high-energy phosphates in the isolated, functioning perfused rat kidney, while monitoring oxygen consumption, glomerular filtration rate and sodium reabsorption. Compared with enzymatic analysis, 100% of ATP, but only 25% of ADP and 27% of Pi are visible to NMR. This is indicative that a large proportion of both ADP and Pi are bound in the intact kidney. NMR is measuring free, and therefore probably cytosolic concentrations of these metabolites. ATP synthesis rate, measured by saturation transfer NMR shows the P:O ratio of 2.45 for the intact kidney. This is close to the theoretical value, suggesting the NMR visible pool is that which is involved in oxidative phosphorylation. The energy cost of Na transport, calculated from the theoretical Na:ATP of 3.0 exceeded the measured rate of ATP synthesis. Instead, Na:ATP for active transport in the perfused kidney was 12. Since the phosphorylation potential ( [ATP]/[ADP]X[Pi] ) by NMR was 10 000 M-1, the free-energy of ATP hydrolysis was 52 kJ/mol. Using this figure, the rate of ATP hydrolysis observed could fully account for the observed rate of sodium reabsorption.

Adenine Nucleotides↗
PubMed1983

Acute mountain sickness, antacids, and ventilation during rapid, active ascent of Mount Rainier.

A double-blind randomized study of 45 climbers on Mt. Rainier was conducted to test the effectiveness of antacids in preventing acute mountain sickness. All 45 climbed to 3353 m, and 31 continued to the summit. Ten climbers listed acute mountain sickness as the reason for not attaining the summit. Of symptoms monitored throughout the climb, neither headache, nausea, dizziness, pounding heart, nor shortness of breath differed in severity between antacid-treated and placebo-treated groups. In both groups vital capacity decreased significantly with ascent (p less than 0.05), while peak flow (p less than 0.005) and minute ventilation (p less than 0.001) increased significantly. The 7 climbers with the most severe AMS symptom scores above 4000 m had significantly lower peak flow at sea level prior to ascent compared with the other 25 climbers who completed sea level tests (p less than 0.005). The results of this study fail to document efficacy for antacid use for the prevention of acute mountain sickness.

Adult↗
PubMed1983

Postoperative hypocalcemia - its relation to operative techniques.

The relationship between the type of operation for primary hyperparathyroidism and the incidence of postoperative hypocalcemia has not been completely elucidated. The pre- and postoperative serum calcium concentrations in 107 patients with this disease who were operated upon for the first time utilizing several different procedures were evaluated. Group 1. Prior to 1978, our aim was the excision of an adenoma, if present, and any other questionably enlarged parathyroid glands. All other appearing glands that could be found were biopsied. If parathyroid normal hyperplasia was present clinically, three and one-half glands were removed. Group 2. (1980 through 1981). A bilateral neck exploration was performed. If an adenoma was present, this was removed. However, only one or two other parathyroid glands were biopsied. The last normal appearing gland was intentionally left undisturbed. If hyperplasia was present, 2 glands were resected and remnants of two other glands were left in situ. Following their initial neck exploration, 52 of 57 (91%) Group 1 patients were cured. During the first 4 postoperative days, 48% had one or more serum calcium values of 7.9 mg/dl or lower (our criterion for significant postoperative hypocalcemia). None had permanent hypoparathyroidism, however. Their serum calcium concentrations fell to the same level whether one, two or three glands were excised. All 50 patients in Group 2 were cured by their initial neck exploration. Only 26% developed serum calcium values of 7.9 mg/dl or lower (p less than 0.05. when compared to Group 1). However, one patient who had the removal of a large substernal goiter and a parathyroid adenoma has manifested prolonged hypocalcemia. Our data demonstrate that by performing a more conservative operation, transient postoperative hypocalcemia can be lessened. Furthermore, it is quite suggestive that excessive parathyroid biopsy may be deleterious and should be avoided.

Adenoma↗
PubMed1982

Invited commentary: an overview of pancreas transplantation--biologic aspects.

The clinical results of vascularized pancreas transplants have improved somewhat during the last 5 years, the but technical problems of handling the pancreatic duct remain difficult. Clinical isolated islet allografts have rarely if ever succeeded. Rejection appears to be a more severe problem in pancreas or islet transplants than in other pancreas transplants. Nevertheless, if nonendocrine cells can be completely removed, transplanted beta-cells might have prolonged survival, since they probably lack Ia antigens that may be necessary to evoke an immune response. An additional biologic problem is the possible destruction (independent of rejection) of transplanted islet cells by autoimmune insulitis. This has been found to occur in spontaneously diabetic rats who received transplanted islets. Study of this animal model may provide important clues to the etiology and treatment or prevention of diabetes.

Animals↗