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Biomedical subjects

L Scott

Publications and source records attributed to L Scott.

At least 487 records · Page 27Linked to original sources
PubMed1989

Scheduling lectures in a teaching hospital.

A modelling technique has been devised that can be used to assist in scheduling lectures for medical students in teaching hospitals. The model takes into account the various clinical commitments that are faced by students and the fact that some of these commitments have a fixed timetable while others are relatively flexible. A simple model is framed for the conflict caused by a particular lecture period in terms of the number of commitments which clash. A computer program has been written that produces graphical output illustrating the effects of various scheduling options. The output from the computer program can be used by decision-makers to examine different options for scheduling lectures and also to explore the effects of rescheduling other clinical activities where there is flexibility so to do.

Computer Simulation↗
PubMed1989

Inhibition of ovarian cancer cell proliferation in vivo and incorporation of 3H-thymidine in vitro after follicle regulatory protein administration.

Follicle regulatory protein immunoreactivity and biologic activity were measured in ascites from a patient with juvenile granulosa cell tumor. Microscopic examination of immunohistochemical staining of a juvenile granulosa cell tumor with anti-follicle regulatory protein antisera showed homogeneous cytosolic expression of follicle regulatory protein throughout the tumor. Tumor cells were injected subcutaneously into nude mice. Partially purified follicle regulatory protein (50 micrograms/day) was then injected daily for 10 days, or for 25 days once the tumor became palpable. Treatment with follicle regulatory protein significantly slowed the rate of tumor growth with both treatments. To test the tissue specificity of the effect, a metastatic, well-differentiated endometrial adenocarcinoma was also grown in nude mice. Follicle regulatory protein treatment did not alter the rate of tumor growth. An in vitro clonigenic assay confirmed these in vivo results. Partially purified follicle regulatory protein had a biphasic effect on the proliferation of juvenile granulosa tumor cell but did not affect the proliferation of endometrial adenocarcinoma cells. Clonigenic assays were performed on five ovarian adenocarcinomas passaged in vitro, and these tumor cells exhibited a biphasic response to follicle regulatory protein. Immunoneutralization studies showed that this biphasic response was due to impurities in the follicle regulatory protein preparations. The longer the exposure of the tumor cells to follicle regulatory protein, the greater the degree of inhibition of proliferation. In summary, administration of follicle regulatory protein slowed tumor growth through a direct effect on the tumor cell rather than an indirect effect on the hormonal or immune status of the host.

Adenocarcinoma↗
PubMed1988

Effects of tolmetin sodium dihydrate on normal and postsurgical peritoneal cell function.

Recent studies utilizing intraperitoneal (i.p.) administration of NSAIDs to rabbits after surgical injury to the parietal peritoneum demonstrated macrophage involvement. NSAIDs are known to inhibit the metabolism of arachidonic acid to prostaglandins, which in turn modulate a variety of macrophage functions. Studies presented here examine the effects of tolmetin administration on peritoneal resident and post-surgical leukocyte functions, such as phagocytosis, the release of superoxide anion and tumoricidal activity. Rats, either non-surgical or following peritoneal surgery, were injected i.p. with tolmetin. At various times after treatment, the rats were sacrificed and peritoneal cells collected by lavage. The phagocytic capability of peritoneal leukocytes was transiently decreased 5-7 days after the administration of tolmetin to normal animals. However, administration of tolmetin during surgery extended the length of time that phagocytic capability was enhanced. In non-surgical controls, there was an elevation in superoxide anion release and tumoricidal activity 24 h after tolmetin administration. Superoxide anion release was suppressed at days 5 and 7 after treatment, but returned to control levels by day 14. Intraoperative administration of tolmetin significantly elevated superoxide anion release at days 3 and 5, phagocytosis at days 7 and 14 and tumoricidal activity at day 3. These studies suggest that compounds which suppress prostaglandin synthesis can modulate the function of resident and post-surgical peritoneal cells.

Animals↗
PubMed1988

Inflammatory pseudotumors in children.

Inflammatory pseudotumors are so named because they mimic malignant tumors clinically and radiologically. Most often seen in the lungs of young adults, they consist of localized proliferations of mononuclear inflammatory cells and myofibroblasts. There are scattered reports of these tumors occurring in various sites in children. We report five cases of these rare lesions in children; four arising intraabdominally and one in the lung. In contrast to the usual presentation in adulthood, these children were all previously healthy. One child, with the tumor arising from the urinary bladder, was originally diagnosed as having a malignant sarcoma and underwent pelvic exenteration and chemotherapy for this subsequently-proven benign lesion. Local recurrence occurred in one case. Total excision is indicated and is usually possible without unacceptable morbidity. Our cases and a review of the literature point out the importance of pathologic differentiation of these lesions from malignancy with early appropriate surgery.

Child↗
PubMed1987

A comparative study of the rate-limiting enzymes of cholesterol synthesis, esterification and catabolism in the alloxan-induced diabetic rat and rabbit.

1. Hyperlipidaemia is associated with diabetes mellitus. 2. A comparison of cholesterol synthesis and utilization in alloxan-induced diabetic rats and rabbits revealed that interspecies differences existed only in the response of the key enzymes regulating cholesterol utilization, namely cholesterol 7 alpha-hydroxylase and ACAT in the liver and intestine respectively. 3. The activity of cholesterol 7 alpha-hydroxylase was enhanced in diabetic rats but was markedly reduced in diabetic rabbits. 4. Intestinal ACAT activity, though unchanged in diabetic rats was reduced in diabetic rabbits. 5. Such species differences in cholesterol utilization may underlie the different degree of susceptibility to hypercholesterolaemia that exists between these two species.

Animals↗
PubMed1987

A comparative study of the rate-limiting enzymes of cholesterol synthesis, esterification and catabolism in the rat and rabbit.

1. The rat and rabbit are amongst the animal models most widely used in the study of human atherosclerosis, a disease state correlating with disturbances in cholesterol metabolism. 2. In order to relate the key regulatory enzymes of cholesterol synthesis, esterification and catabolism in the rat and rabbit to their differing degree of susceptibility to atherosclerosis, enzyme levels and their properties were determined in liver and intestine of both species. 3. Hepatic HMG CoA reductase and cholesterol 7 alpha-hydroxylase levels were significantly higher in the rat than in the rabbit, while intestinal HMG CoA reductase activity in the two species was comparable. Conversely, the capacity to esterify cholesterol as measured by ACAT activities was considerably greater in both sites in the rabbit compared to the rat. 4. The data suggest that differences in the key regulatory enzymes of cholesterol metabolism in both liver and intestine may reflect different methods of cholesterol utilization in the two species.

Animals↗
PubMed1987

Changes in collagen fibril diameters across artery walls including a correlation with glycosaminoglycan content.

Collagen fibril diameters were measured at regular intervals across the walls of numerous arteries from human, pig and rat. In all vessels the smallest fibrils (mean-fibril diameters of 30-40 nm) occurred in the intima and inner media and the largest fibrils (MFDs 50-100 nm) in the outer adventitia. Between these two regions fibrils progressively increased in size. Circumferential and axial fibrils were of similar size and showed similar patterns of increase. At each sample site there was a range of diameters and frequency distributions were often multimodal with peaks 8 nm, or multiples of 8 nm, apart. Amounts of total and individual glycosaminoglycans (GAG) were determined at regular intervals across the wall of pig aorta and total and sulphated GAG levels were also determined at intervals across rat carotid artery using autoradiographic detection of incorporated [3H] glucosamine and 35S. In both vessels there was a strong correlation between decreasing GAG and increasing MFDs and over a narrow MFD range of 40 to 60 nm. These results demonstrate that collagen fibril diameters are excellent indicators to GAG levels and may be useful for making predictions about GAG levels in areas too small to sample biochemically.

Adult↗
PubMed1986

Carcinoma of the colon--association with low dietary vitamin A in females: preliminary communication.

Seventeen patients with non-metastatic carcinoma of the colon (9 male, 8 female) were compared with age- and sex-matched controls in a study examining the relationship of diet and altered cholesterol metabolism with carcinoma of the colon. Bile acid excretion in the faeces was significantly less in cancer patients (P less than 0.001), and a significantly lower intake of retinol (P less than 0.01) and vitamin A (P less than 0.05) was demonstrated in female cancer patients. There was no difference between patients and controls in hepatic cholesterol enzyme activity or in fasting plasma lipid levels.

Aged↗
PubMed1985

Selenium prevents mercuric chloride induced acute osmoregulatory failure without glutathione peroxidase involvement in the black bullhead (Ictalurus melas).

The relationship between coelomic injections of mercuric chloride doses and osmoregulatory responses was measured. Response parameters were weight increases and blood osmolarity decreases 72 hr after dose administration. Massive edema and large decreases in blood osmolarity could be completely prevented by subcutaneous injections of equimolar sodium selenite. Mercury induced damage did not involve alterations of either selenium-dependent or non-selenium-dependent glutathione peroxidase activities.

Animals↗
PubMed1982

Effect of pregnancy on gastrointestinal transit.

In order to evaluate the possible effects of pregnancy-associated sex steroids on gastrointestinal function, we determined gastrointestinal transit times and sex steroid levels in 15 women during the third trimester of their pregnancies and again 4--6 weeks following delivery when gastrointestinal function had symptomatically returned to normal. Gastrointestinal transit time from ingestion of a liquid lactulose meal to its delivery to the cecum was determined by monitoring breath hydrogen concentrations at 10-min intervals. Gastrointestinal transit times were significantly prolonged in the third trimester of pregnancy, when progesterone and estradiol levels were increased, compared to the postpartum period. This study supports previous findings which suggest that increasing levels of progesterone and estradiol affect gastrointestinal function and therefore may contribute to gastrointestinal symptoms that often occur in pregnant women.

Adult↗
PubMed1982

Organ culture of rat carotid artery: maintenance of morphological characteristics and of pattern of matrix synthesis.

Segments of rat carotid artery were maintained in serum-free or serum-supplemented medium for 2 wk, and at intervals of 3, 7, and 14 d the morphology and pattern of matrix synthesis were compared to those in vivo. In serum-free medium and 0.2% serum both the endothelium and the smooth muscle cells (SMC) could be maintained with a minimum of change for 7 d and without substantial change for 14 d. In 2% and 10% serum there was little change for the first 3 d, but subsequently there was a progressive overlapping of the endothelial cells to produce a 3 to 4 layered cell sheet, often separated from the subendothelial matrix; the SMC, however, did not appear to proliferate or migrate and in general retained their typical cellular features for the full time in culture. The synthesis of matrix components was measured by autoradiographic detection of incorporated [H]glucosamine and 35S. At all time periods and serum concentrations the percentage distribution for each label across the arterial wall was found to be similar to that in live animals injected with the same labels. [3H]Glucosamine predominated in the endothelium and the narrow subendothelial layer, which together make up the intima, whereas 35S predominated in the media. In vitro more than 50% of the [3H]glucosamine in the intima and 40% in the adjacent first layer of the media was susceptible to Streptomyces hyaluronidase. As the morphology of both cell types and their synthesis of matrix components could be maintained in organ culture without substantial change we believe that the rat carotid artery may be a suitable model for the investigation of factors affecting arterial structure.

Animals↗
PubMed1982

Relaxation training and cognitive redirection strategies in the treatment of acute pain.

Relaxation training, relaxation instructions, and redirection of attention techniques were compared to a no-treatment control in the treatment of acute ischemic pain. Relaxation instructions were ineffective in reducing state anxiety, verbally reported pain or distress or pain measured during presentation of the stimulus by cross-modality matching. Relaxation training was effective in reducing distress during presentation of the stimulus and verbally reported pain. The attention-redirection technique reduced pain as measured by cross-modality matching. The interaction hypothesis was supported, re. the two measures of distress during presentation of the painful stimulus. As externality increased, the effectiveness of relaxation training increased. However, there was no consistent decrease in distress for subjects high on externality in the relaxation instruction group.

Attention↗