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Biomedical subjects

M E Bell

Publications and source records attributed to M E Bell.

At least 37 records · Page 2Linked to original sources
PubMed1987

Use of platelet concentrate in eastern Ontario.

To better understand the reasons for the increasing use of platelet concentrate in Canada, we undertook a 4-month study of platelet concentrate transfusion in six eastern Ontario hospitals in 1985. A total of 4801 units of platelet concentrate were transfused on 687 occasions to 303 patients; the average number of transfusions per patient was 2.3, the average number of units per transfusion 7.0 and the average number of units per patient 15.8. The cardiovascular service used the largest proportion of units (28%), aortocoronary bypass grafting being the most common procedure. The mean pretransfusion platelet count for the medical and oncology services was about 30.0 X 10(9)/L, compared with 155.5 X 10(9)/L for the cardiovascular service. An increment in platelet count 1 hour after transfusion was noted with 238 (75%) of the transfusions for which the data were available; the average increment was 3.4 X 10(9)/L per unit of platelet concentrate transfused. When the data for patients who did not respond were excluded, the average increment was 6.9 X 10(9)/L. Single-donor platelet concentrate was requested for only half of the transfusions to which no response was detected. The current medical literature supports the appropriate use of platelet concentrate in patients with thrombocytopenia due to chemotherapy, but prophylactic platelet transfusion for patients undergoing cardiovascular bypass procedures is being questioned. We advise continued surveillance of the use of these products and re-evaluation of the aims of platelet transfusion therapy.

Blood Transfusion↗
PubMed1987

Primary carcinosarcoma: a rare cause of unilateral ureteral obstruction.

We report a case of unilateral ureteral obstruction owing to carcinosarcoma of the distal ureter. Tumor recurred 6 months after ureteronephrectomy and the patient died 2 1/2 years later. A review of the literature revealed only 3 other cases of ureteral carcinosarcoma, all of which had a similar aggressive course. Recognition and separation of this entity from the more usual transitional cell carcinoma are important because of its apparent poorer prognosis.

Aged↗
PubMed1985

Decreased incorporation of [3H]inositol and [3H]glycerol into glycerolipids of sciatic nerve from the streptozotocin diabetic rat.

The incorporation of [3H]myo-inositol into individual phosphoinositides and of [3H]glycerol into glycerolipids was determined in sciatic nerve obtained from normal and streptozotocin diabetic rats and incubated in vitro. The uptake of inositol into lipid was approximately linear with time. More than 80% of the label was present in phosphatidylinositol with the remainder divided about equally between phosphatidylinositol phosphate and phosphatidylinositol-4,5-bisphosphate. Labeling was unchanged 2 weeks after induction of diabetes, but was reduced by 32% after 20 weeks of the disease. Glycerol incorporation occurred primarily into phosphatidylcholine and triacylglycerol and was depressed up to 45% into major phosphoglycerides in nerves from both 2- and 20-week diabetic animals. Triacylglycerol labeling was also substantially decreased, and the reduction was comparable in intact and epineurium free nerve, suggesting that a metabolically active pool of this compound, which is sensitive to hyperglycemia and/or insulin deficiency, is located in or immediately adjacent to the nerve fibers. The considerable decline in incorporation of these lipid precursors in diabetic nerve may be related to impaired inositol transport and to decrease overall energy utilization by the tissue.

Animals↗
PubMed1983

Postnatal increase in the metabolism of leucine and valine.

The catabolism of tritium-labeled leucine, valine, and glycine was determined by measuring the appearance of tritium-labeled water at various postnatal and adult ages in rats. Results for leucine and valine show a marked increase in the formation of labeled water during the 3rd postnatal week. The partial exclusion of leucine and valine from brain, as a result of the blood-brain barrier, particularly enhances observation of labeled water formation in that the product (water) and precursor (amino acid) are largely separated (supporting experiments demonstrate the prior existence of the blood-brain barrier for leucine). Results for glycine indicate its extensive metabolic degradation at all postnatal ages. These data indicate that the metabolic rate of intraperitoneally administered, radioactively labeled leucine and valine changes appreciably during early postnatal development. The early postnatal manifestation of human disorders of branched-chain amino acid metabolism is consistent with the chronology of development in the rat.

Age Factors↗
PubMed1982

Synthesis of myelin, particulate, and soluble protein subfractions of rat sciatic nerve during the early stage of Wallerian degeneration: a comparison of metabolic studies using double and single isotope methods and recovery.

The recovery, electrophoretic composition and synthesis of the myelin, particulate protein and soluble protein subfractions of rat sciatic nerve were compared in normal, sham-operated, and degenerating rat sciatic nerve at one, three and five days after neurotomy. Both single and double isotope methods were used to measure changes in synthesis in vitro and double isotope methods were used in vivo. The wet weights of nerves undergoing Wallerian degeneration for 5 days increased by 40 percent compared to normal and sham-operated nerves. The recovery, specific radioactivity, and synthesis of the myelin was reduced. The effect on myelin protein synthesis was similar in vitro and in vivo. The myelin loss was relatively constant in amount (30-40 microgram) regardless of differences in nerve sizes of young and old rats, consequently the percentage of myelin loss was inversely proportional to nerve size. The recovery of particulate protein increased, its rate of synthesis remained unchanged, and accordingly the specific radioactivity was decreased. The recovery, specific radioactivity, and the rate of synthesis of the soluble protein fraction were all elevated. The protein composition of the three fractions, as analyzed qualitatively by polyacrylamide disc gel electrophoresis, remained essentially unchanged through five days of degeneration. With regard to comparisons of the single and double isotope methods, results shows that the latter are more ideally suited to measuring changes in synthesis during the non-steady state conditions that are characteristics of rapid degeneration.

Animals↗
PubMed1982

Metabolism of phospholipids in peripheral nerve from rats with chronic streptozotocin-induced diabetes: increased turnover of phosphatidylinositol-4,5-bisphosphate.

The effect of chronic streptozotocin-induced diabetes on phospholipid metabolism in rat sciatic nerve in vitro was investigated. In normal nerve incubated for 2 h in Krebs-Ringer-bicarbonate buffer containing [32P]orthophosphate, radioactivity was primarily incorporated into phosphatidylinositol-4,5-bisphosphate and phosphatidylcholine. Smaller amounts were present in phosphatidylinositol-4-phosphate, phosphatidylinositol, and phosphatidic acid. As compared to controls, phosphatidylinositol-4,5-bisphosphate in nerves from animals made diabetic 2, 10, and 20 weeks earlier accounted for 30-46% more of the isotope, expressed as a percentage, incorporated into all phospholipids. In contrast, the proportion of radioactivity in phosphatidylcholine decreased by 10-25%. When the results were expressed as the quantity of phosphorus incorporated into phospholipid, only phosphatidylinositol-4,5-bisphosphate displayed a change. The amount of isotope which entered this lipid increased 60% and 67% for 2- and 10-week diabetic animals, respectively. Increased phosphatidylinositol-4,5-bisphosphate labeling was observed when epineurial-free preparations were used or when the composition of the incubation medium was varied. Sciatic and caudal nerve conduction velocities were decreased after 10 and 20 weeks but were unchanged after 2 weeks. We conclude that an increase in the turnover of phosphatidylinositol-4,5-bisphosphate in sciatic nerve from streptozotocin-diabetic rats appears relatively early and persists throughout the course of the disease. This metabolic alteration may be related to a primary defect responsible for the accompanying deficient peripheral nerve function.

Animals↗
PubMed1981

Effects of polyamines on calcium-dependent rat brain phosphatidylinositol-phosphodiesterase.

The effect of polyamines on the ability of calcium-dependent soluble rat brain phosphatidylinositol-phosphodiesterase to hydrolyze dispersed phosphatidylinositol was examined. Putrescine and cadaverine stimulated activity at all concentrations tested. In contrast, spermine and spermidine stimulated the reaction slightly at low concentrations but caused progressively greater inhibition as their levels were further increased. Phosphatidylinositol hydrolysis was inhibited by several multivalent cations, especially lanthanum and manganese. Spermidine partially replaced the calcium requirement of the enzyme. The possibility that polyamines may play a role in the regulation in vivo of phosphatidylinositol-phosphodiesterase is discussed.

Animals↗
PubMed1980

Acinic cell tumors of minor salivary glands.

The occurrence of acinic cell tumors in the minor salivary glands of the oral cavity has, until recently, been considered exceptional. However, three recent papers have documented the details of fifty-two such cases. The purpose of the present article is to record the clinical information and histologic findings in six additional, previously unreported, examples of this tumor in the minor salivary glands.

Female↗
PubMed1980

Pattern of myelin breakdown during sciatic nerve Wallerian degeneration: reversal of the order of assembly.

Myelin sheaths of rapidly growing rats were sequentially labeled with the 3H and 14C isotopes of leucine as precursors of protein synthesis. The two injections were separated by time intervals ranging from 2 to 12 d. Wallerian degeneration was initiated by sciatic nerve neurotomy at 2 or 10 d after the second injection of radioactivity. After 5 d of degeneration, myelin was purified and the ratio of isotopes was determined in the delipidated protein. Regardless of the order in which the two isotopes were administered, the relative recovery of radioactivity resultant from the second injection was greatly reduced in degenerating nerves compared with sham-operated controls. Radioactivity incorporated from the first injection was also reduced, but to a lesser extent. Consequently, the isotope ratio corresponding to the first/second injection was greater in degenerating nerves than in controls, and the ratio increased in proportion to the time interval separating the two injections. The magnitude of the effect of degeneration was only slightly greater when degeneration was initiated 2 d after the second injection than when initiated 10 d after the last injection. Consequently, myelin disintegration rather than diminished incorporation of radioactivity accounts for the losses of radioactivity. Furthermore, the pattern of myelin degeneration preferentially involves the last myelin to be formed.

Animals↗
PubMed1979

Morphologic features of prognostic significance in uterine smooth muscle tumors: a review of eighty-four cases.

Independent microscopic review of the most cellular and pleomorphic areas of 84 smooth muscle tumors of the uterus by two pathologists yielded 23 leiomyosarcomas, 43 cellular leiomyomas, 16 bizarre leiomyomas, and two intravenous leiomyomas. Greater than 5 mitotic figures/10 high-power fields (hpf) correlated with malignant clinical behavior, but this occurred in only 75% of the leiomyosarcomas. Five cases with fewer than 5 mitoses/10 hpf pursued a malignant course. The mean age of the patients with malignant tumors (52.5 years) was similar to the mean age of those with bizarre leiomyomas (48.0 years) but those patients with cellular leiomyomas were significantly younger (42.0 years; p less than 0.01). Gross evidence of extrauterine extension was diagnostic of malignancy as was vascular invasion by anaplastic tumor. Fifteen of the 19 patients with leiomyosarcoma died of disease at an average of 28 months postoperatively. Inadequate sampling and interobserver variation are discussed.

Adult↗
PubMed1979

Lymphatic invasion in pigmented nevi.

All 124 pigmented nevi registered at the Canadian Tumour Reference Centre between July 1958 and May 1969 were reviewed. Nevus cells invading endothelial lined spaces were observed in serial sections from five cases. The significance of this finding is discussed in relation to published reports of the presence of nevus cells in lymph nodes.

Adult↗
PubMed1977

Tubal pregnancy in a 'low-risk' population: occasional association with follicular salpingitis.

Long-standing tubal inflammatory lesions occurred in 35 (14%) of 250 tubal pregnancy patients, aged from 14 to 45 yrs, encountered from 1948 to 1969 in an eastern Canadian population where clinically manifest pelvic inflammation is not prevalent and 1/180 is the approximate ratio of ectopic pregnancy to live births. Present in 24 of these 35 patients was follicular salpingitis. For most of the eccyeses, functional derangements appear likely to have been responsible more often than structural alterations of the oviducts; but possible roles for 'physiological salpingitis' in leading to tubal pregnancy may be worthy of investigation.

Adolescent↗