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Biomedical subjects

G Bennett

Publications and source records attributed to G Bennett.

At least 145 records · Page 8Linked to original sources
PubMed1981

The site of incorporation of sialic acid residues into glycoproteins and the subsequent fates of these molecules in various rat and mouse cell types as shown by radioautography after injection of [3H]N-acetylmannosamine. II. Observations in tissues other than liver.

Biochemical evidence from the preceding paper indicated that [3H]N-acetylmannosamine may be used as a fairly specific precursor for the sialic acid residues of glycoproteins (and perhaps glycolipids) in radioautographs of rat liver and duodenum. In order to study the site of incorporation of this label in cell types of various tissues, we gave 40-g rats and 15-g Swiss albino mice a single intravenous injection of 8 mCi of [3H]N-acetylmannosamine and sacrificed them after 2 and 10 min. To trace the subsequent migration of the labeled glycoproteins, we injected 40-g rats with 4 mCi of [3H]N-acetylmannosamine and sacrificed them after 20 and 30 min, 1, 4, and 24 h, and 3 and 9 d. Light microscope radioautographic analysis revealed that in a great variety of cell types the label was initially localized to the Golgi region. Electron microscope radioautographic analysis of duodenal villous columnar and goblet cells, pancreatic acinar cells and Paneth cells, from rats and mice sacrificed 10 min after injection, showed that the silver grains were localized over Golgi saccules (and adjacent secretion granules). In kidney proximal and distal tubule cells reaction was initially localized to the Golgi apparatus in some areas of the kidney cortex whereas in other areas it was more diffuse. In all cells, the proportion of silver grains over the Golgi apparatus decreased with time after injection while an increasing number of grains appeared over secretion products in secretory cells or over the plasma membrane in other cell types. Lysosomes also became increasingly labeled at later time intervals. The above results suggest that in most cell types sialic acid residues are incorporated into glycoproteins (and perhaps glycolipids), primarily in the Golgi apparatus. With time, these newly synthesized molecules migrate to secretion products, to the plasma membrane, or to the lysosomes.

Animals↗
PubMed1981

Malignant hyperthermia: current perspectives.

The incidence, etiology, clinical manifestations, and management of malignant hyperthermia (MH) are reviewed. The syndrome of MH is recognized as one of the causes of anesthesia-related deaths. It is considered pharmacogenetic because both an abnormal gene and precipitating environmental factors are necessary to produce an acute reaction. Metabolic defects, involving a derangement of calcium dynamics, appear to be the common characteristic of susceptible individuals. Calcium release and uptake from the sarcoplasmic reticulum is altered when an individual with MH is exposed to certain anesthetic agents or triggering physical and emotional stresses. Muscle rigidity, tachycardia, tachypnea, and high fever can lead to other complications and death. Management of an acute reaction of MH includes cooling methods to lower body temperature, hyperventilation, sodium bicarbonate control of acidosis, maintenance of fluid and electrolyte balance, and the administration of dantrolene sodium. A thorough family history, baseline CPKs, caffeine-halothane contracture tests, and ultramicroscopic examination of muscle biopsy specimens are recommended as screening techniques. The early administration of dantrolene sodium in acute reaction of MH has been shown to rapidly alleviate the symptoms and ensuing severe complications. Individuals with a strong family history of MH or previous episodes may be treated with oral dantrolene sodium before surgery to effectively prevent a crisis, and after surgery to prevent recurrence.

Creatine Kinase↗
PubMed1980

Psycho-social aspects of chronic pain in spinal cord injury.

The relationship between persistent pain in spinal cord injury and medical-descriptive, demographic, psychological and familial-social data was studied. Multiple linear regression and discriminant analysis were used to predict (1) presence or absence of pain; (2) severity of pain; (3) time post-injury onset of pain; (4) whether or not pain interfered with activities of daily living. The best combinations of predictor variables accounted for only 15 and 19% of the dependent measures pain vs. no-pain and onset of pain, respectively. The best combinations of predictor variables accounted for 43 and 44%, respectively of the dependent measures severity of pain and whether or not pain interfered with activities of daily living. Higher levels of subjective pain were associated with greater age, higher verbal intelligence, higher levels of anxiety and a more negative psycho-social situation. Persons who reported pain interfering with activities of daily living were more likely to be older, of higher intelligence, more depressed, clinically rated as experiencing greater levels of distress and immersed in a more negative psycho-social environment. The importance of psycho-social variables in the understanding of persistent spinal cord injury pain and the need for prospective studies along these lines are demonstrated.

Activities of Daily Living↗
PubMed1979

Prostacyclin: a solution to some problems of extracorporeal circulation. Experiments in greyhounds.

In cardiopulmonary-bypass experiments in greyhounds the effects of adding prostacyclin, prostacyclin plus heparin, and heparin alone to the extracorporeal circulation were compared. With heparin alone platelet count and function were reduced, the pressure differential across the arterial filters rose, platelet deposits were found on the arterial filters, and plasma-fibrinogen levels fell. Plasma from these dogs was toxic to fetal-mouse hearts in culture. With prostacyclin alone, fibrinogen levels fell, but the platelets were preserved. With a combination of prostacyclin and heparin, platelet count and function were maintained, there was no consumption of fibrinogen, and there was little deposition on the arterial filters.

Animals↗
PubMed1979

Comparison of droperidol, haloperidol and prochlorperazine as postoperative anti-emetics.

The results of this study demonstrate that prochlorperazine, haloperidol and droperidol are all effective post-operative anti-emetic compounds when compared to saline but vary in onset of activity and duration of action. Haloperidol has the shortest onset of action, being effective within 30 minutes of intravenous administration. Prochlorperazine has an intermediate onset of action and droperidol is the slowest of the three compounds but the only one to provide significant anti-emesis 4-24 hours following administration. Our data suggest that a combination of haloperidol and droperidol may be more effective as an anti-emetic than any one of the compounds used alone.

Droperidol↗
PubMed1978

Synthesis and migration of glycoproteins in cells of the rat thymus, as shown by radioautography after 3H-fucose injection.

Young male rats received a single intravenous injection of 3H-fucose and were killed after various time-intervals. Light- and electron-microscopic radioautographic studies of the thymus in animals killed shortly after injection showed that all of the different cell types present incorporated 3H-fucose label. The heaviest uptake occurred in macrophages and in hypertrophic epithelial cells located near the cortico-medullary border. Somewhat lighter incorporation was observed in medullary and cortical stellate epithelial cells and in cells designated as special cells, while the lightest reaction appeared over lymphocytes. In all cells the label was localized initially to the Golgi apparatus, where, presumably, it was incorporated into glycoproteins. With time, some of the labeled putative glycoproteins in all cell types migrated to the plasma membrane. In macrophages, much of the label migrated to lysosomal bodies, while in the special cells the label migrated to dense bodies which may also be of lysosomal nature. In stellate and hypertrophic epithelial cells much of the label migrated to characteristic vacuoles. The possible relationship between the observed glycoprotein synthesis in these cells and hormone production is discussed.

Animals↗
PubMed1977

Formation and turnover of plasma membrane glycoproteins in kidney tubules of young rats and adult mice, as shown by radioautography after an injection of 3H-fucose.

The formation and turnover of the glycoproteins of the plasma membrane have been investigated by quantitative radioautography in the kidney tubules of young rats and adult mice killed at various time intervals after an intravenous injection of 3H-fucose. In young (40 g) rats killed five to ten minutes after the injection, radioautographs of distal tubule cells show that the Golgi apparatus contained about 85% of the cell label. By 30 hours, only 8% of the label remained in this organnele, whereas 67% was in the plasma membrane, indicating that most of the label had migrated from Golgi apparatus to this membrane. Similarly, in proximal tubule cells, about 82% of the label was initially in the Golgi apparatus, but less than 2% remained at 30 hours, at which time 78% was in the plasma membrane. In the latter cells, the apical tubules and vacuoles became heavily labeled before the apical microvilli did and, therefore, may be involved in the transit of label from the Golgi apparatus to the microvillous membrane. The results are interpreted to mean that, in kidney tubule cells, the Golgi apparatus is the site of a continuous incorporation of fucose into glycoproteins and that these migrate to the plasma membrane. In fully formed cells, such a conclusion would imply a continuous turnover of plasma membrane glycoproteins. However, in the rapidly growing kidney of young rats many new cells are added daily, the growth of which might involve net addition as well as turnover of glycoproteins. Accordingly, the experiment has been repeated in adult mice, in which the cells are assumed to be fully formed. Furthermore, since turnover implies eventual decrease of incorporated label, some of the animals have been killed at longer intervals, up to 27 days after injection. In these adult mice, as in young rats, prompt Golgi uptake and subsequent migration of label to the plasma membrane were observed in distal and proximal tubules cells. With time the label content of the plasma membrane decreased gradually, and by 27 days had virtually disappeared. From grain counts, it is concluded that the mean half-life of glycoproteins in the apical membrane of distal tubule cells is about two days, whereas in both the apical and basal membranes of proximal tubule cells, it is slightly over three days.

Age Factors↗
PubMed1977

Secondary liposarcoma of the ovary.

This report is the first description of a secondary ovarian liposarcoma. The primary growth was in the mediastinum. The growth rate of the ovarian tumor was very rapid, but the patient died of cardiopulmonary causes. The mode of spread is discussed, and it probably occurred by transcelomic migration and surface implantation.

Adult↗
PubMed1977

A non-chromatographic radioimmunoassay of testosterone in serum.

Convenient methodology based on separation of testosterone from non-alcoholic neutral steroids by means of a sulfation procedure has been developed for the radioimmunoassay (RIA) of testosterone in male and in female serum. When coordinated with our previously published non-chromatographic procedure (1) for the RIA of estrone and 17 beta-estradiol in serum all 3 steroids can be determined in the same specimen. With only minor modification (14) progesterone also can be determined. Validation of the procedure was based on: 1. agreement between results obtained using TLC and sulfation to fractionate testosterone (r=0.99; b=1.03), 2. accurate recovery of different quatities of testosterone added to serum, 3. independence of the concentration of testosterone and volume of serum used for assay, 4. low procedural blanks (1.1+/-0.7 pg), 5. low intra-assay (4.7-4.8%) and interassay (4.8-8.8%) variability and 6. correspondence of observed values for testosterone in male serum (7.00+/-2.03 ng/ml) and in femal serum (420+/-115 pg/ml) with those reported previously by others.

Animals↗