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Biomedical subjects

C Watts

Publications and source records attributed to C Watts.

At least 181 records · Page 10Linked to original sources
PubMed1982

Neurosurgical manpower: the physician's viewpoint.

This paper reports a national study of physicians in 24 medical and surgical specialties, and reveals the opinions of neurosurgeons and their professional colleagues with regard to the adequacy of the supply of neurosurgical manpower. Among neurosurgeons, 30.4% believe the supply to be excessive, 60.1% think it is about right, 7.5% believe that there is a shortage, and 2.0% have no opinion. Neurologists' opinions do not differ significantly from those of neurosurgeons, but physicians and surgeons in 22 other specialties are significantly less likely to regard the supply as excessive and are more likely to perceive a shortage. Primary care physicians, as a group, are most likely to perceive a shortage, and least likely to indicate an excess. Among the 24 specialties studied, 9.3% of physicians believe the supply of neurosurgeons to be excessive, 55.1% think it is about right, 22.9% believe that there is a shortage, and 12.8% have no opinion.

Attitude of Health Personnel↗
PubMed1981

Liver glycogen synthase in the developing foetal rat.

Kinetic constants for liver glycogen synthase (UDPglucose: glycogen 4-alpha-D-glucosyltransferase, EC 2.4.1.11) with respect to UDPglucose have been measured in foetal liver homogenates from samples taken during late gestation (days 17-22) and the first hours after birth. The V of the inactive form of glycogen synthase increased markedly in this period and there was a significant increase in V of the active enzyme to a maximum at day 20 of gestation. The Km for UDPglucose measured in the presence of glucose-6-P (total activity) did not vary greatly, mean values of 0.51 +/- 0.04 mM. Values derived for the inactive enzyme were almost identical. In contrast, Km values for active glycogen synthase in foetal livers during gestation were significantly higher than those for adult liver. Highest values were seen at day 19 of gestation (1.84 +/- 0.08 mM) followed by a steady fall to 0.55 +/- 0.05 mM in the newborn compared with a mean value of 0.48 +/- 0.04 mM for adult liver. Existence of a reduced affinity of active glycogen synthase for UDPglucose must be recognized when assaying the enzyme in foetal liver, particularly when extrapolating values to rates of glycogen synthesis in vivo. Data were obtained only after removal of an amylase-like contaminant from foetal liver samples which invalidated the radioassay of glycogen synthase. This work illustrates the care needed in the analysis of foetal tissue and the interpretation of resulting data when utilizing methods developed for adult tissue.

Amylases↗
PubMed1981

Membrane assembly from purified components. I. Isolated M13 procoat does not require ribosomes or soluble proteins for processing by membranes.

The coat protein of coliphage M13 is an integral protein of the host-cell cytoplasmic membrane prior to its assembly into virions. It is initially synthesized as procoat, a soluble precursor with a 23 amino acid leader sequence at its amino terminus. 35S-labeled procoat accumulates during an in vitro translation reaction that contains 35S-methionine and RNA from M13-infected cells. Radiochemically pure procoat has been isolated from in vitro translation reactions by extraction into an organic solvent and gel filtration through Sephadex LH-60. Radiochemically pure procoat can be used as substrate in rapid and quantitative assays for leader peptidase and for leader peptide hydrolase, an enzyme that degrades the leader peptide after its release from procoat. Procoat solubility, digestion by leader peptidase and processing by membranes are affected by the presence of Mg2+ ion. Isolated procoat is soluble in water at low ionic strength and mildly alkaline pH as well as in detergent solutions. It is cleaved to coat protein by purified E. coli leader peptidase and by inverted E. coli inner-membrane vesicles. These properties of the purified procoat mirror those of the procoat in crude extracts. This suggests that there are no other soluble components that are necessary for the assembly of procoat into the membrane and its conversion to coat; specifically, it provides powerful evidence that protein synthesis is not involved.

Cell Membrane↗
PubMed1981

Membrane assembly from purified components. II. Assembly of M13 procoat into liposomes reconstituted with purified leader peptidase.

The major coat protein of coliphage M13 is an integral protein of the E. coli plasma membrane prior to its assembly into new virus particles. It is generated from its precursor, procoat, by a membrane-bound leader peptidase. We now describe the reconstitution of a highly purified preparation of this enzyme into vesicles of E. coli phospholipids. These vesicles bind procoat made in vitro and procoat isolated from in vitro synthesis. Both the crude and the purified substrates were converted post-translationally to coat protein. A significant proportion of the coat protein becomes inserted into the vesicle bilayer, with the N terminus facing the vesicle interior and the C terminus exposed to the external medium. These results strongly suggest that highly purified leader peptidase from E. coli and phospholipids are the only components necessary to mediate the binding, processing and insertion of this integral membrane protein.

Coliphages↗
PubMed1981

Membrane assembly: posttranslational insertion of M13 procoat protein into E. coli membranes and its proteolytic conversion to coat protein in vitro.

The major coat protein (gene 8 product) of bacteriophage M13 is an integral membrane protein during infection of host cells. It is synthesized as a larger precursor (procoat) with a leader sequence of 23 amino acids at its amino terminus. In vivo studies have shown that procoat only inserts into the host-cell plasma membrane after its synthesis is completed. We now demonstrate that procoat can post-translationally insert into inverted cytoplasmic membrane vesicles from E. coli and can be processed proteolytically to yield coat protein. Procoat changes from an assembly-competent substrate to an incompetent (denatured) form within minutes after its synthesis; much of the procoat that accumulates during an hour of in vitro synthesis is therefore denatured. These studies emphasize the importance of stringent criteria for the demonstration of obligate cotranslational assembly.

Cell Membrane↗
PubMed1981

Glucose homeostasis during the perinatal period in normal rats and rats with a glycogen storage disorder.

The fetal rat mobilizes liver glycogen during parturition for use as a glucose source until the onset of gluconeogenesis at 2 h after birth. A rat strain (NZR/Mh) unable to mobilize liver glycogen because of a phosphorylase b kinase deficiency has been used to assess the importance of liver glycogen in glucose homeostasis of the newborn. In normal rats the mean blood glucose concentration of the fetus measured at various times up to 24 h after natural birth ranged between 3.7 and 5.4 mM. In contrast, fetuses of the affected rats were hypoglycemic before birth (2.02 +/- 0.15 mM), and by 1 h after birth the blood glucose had decreased to 0.74 +/- 0.14 mM. Concentrations increased by 4 h to 1.48 +/- 0.17 mM and by 24 h reached values not significantly different from the normal newborn rats. Changes in plasma insulin over the perinatal period were similar in both groups although concentrations were always significantly lower in the affected rts. The findings demonstrate the crucial role of the fetal liver glycogen store in the maintenance of normoglycemia in the newborn. The normal rat does not develop hypoglycemia when born naturally and left with the mother after birth (in contrast to other studies in which the newborn were taken by cesarian delivery 1 d prematurely and kept in an artificial environment without food). The rats with the glycogen storage disorder experienced severe hypoglycemia without any apparent effects, which raises questions concerning alternative fuels available to and utilized by the newborn.

Animals↗
PubMed1981

Neurosurgery in the United States: a log-diary study.

The Division of Research in Medical Education and of the University of Southern California, with the cooperation and assistance of the American Association of Neurological Surgeons and the Congress of Neurological Surgeons, has conducted a national study of the professional activities of neurological surgeons in the United States. One of a series of 24 surveys of medical and surgical specialties, the survey obtained information on patient workloads, the allocation of physician time, the characteristics of patients and the circumstances under which they were seen, patient diagnoses, and the care that was provided--including whether an operation was performed. This paper provides a selection of the findings deemed most relevant to manpower issues in neurosurgery. A later paper will examine regional differences in patient care, including the frequency with which selected surgical procedures are used for different clinical conditions.

Commission on Professional and Hospital Activities↗
PubMed1981

Relationship between visual evoked potentials and intracranial pressure.

The relationship between intracranial pressure (ICP) and latency of visual evoked potentials (VEP) was investigated in hydrocephalic patients with severe head trauma. A positive correlation of increase in latency of wave N2 (normal latency 71 +/- 9.2 msec) of the VEP with elevations in ICP was observed. A potential role for VEP in both the assessment of shunt function and the monitoring of patients with severe head injury is suggested by these findings.

Adolescent↗
PubMed1980

The characterisation of two partially purified systems for Na+-dependent amino acid transport.

Two systems mediating the transport of amino acids were studied in vesicles derived from protein-depleted membranes of pigeon erythrocytes. One system (ASC system) catalysed the Na+-dependent exchange of small neutral amino acids, such as alanine, serine and cysteine. The other system, also Na+-dependent, mediated the active transport of glycine. The ASC and glycine systems were distinguished by the sensitivity of the latter to the anion present, by the former's requirement for an exchangeable amino acid and by the inability of alanine to inhibit the transport of glycine. Preliminary results indicated that the influx of glycine was electrically silent. The only major integral protein retained in the vesicles was the band 3 protein, but that could not be unequivocally identified as the transporter.

Alanine↗
PubMed1980

The formation of vesicles retaining sodium-dependent transport systems for amino acids from protein-depleted membranes of pigeon erythrocytes.

The process of the formation of vesicles from pigeon erythrocyte membranes was studied. Mildly alkaline solutions of low ionic strength, which reduce human erythrocyte membranes to small vesicles depleted of spectrin and other proteins, have no such effect on pigeon erythrocyte ghosts. A distinct phase of removal of membrane proteins, including spectrin, began to occur only when pigeon erythrocyte membranes were exposed to 0.2 mM EDTA adjusted to pH values above 10.2. Vesicles which demonstrated Na+-dependent amino acid transport were generated between the pH values 10.8 and 11.4. The results show that peripheral proteins, notably spectrin, maintain the integrity of the pigeon erythrocyte ghost. The interaction of these proteins with the membrane is rather different from that well studied in the human erythrocyte ghost and the possible significance of this for the pigeon erythrocyte is discussed.

Alanine↗
PubMed1980

Spinal cord glioma following irradiation for Hodgkin's disease.

A 21-year-old patient, after radiation therapy to the mediastinum for Hodgkin's disease, died six years later of a spinal cord glioma, believed to be caused by irradiation therapy. That the x-ray therapy provoked neoplastic changes seems likely, although it could be coincidental.

Adult↗
PubMed1980

Glycogen-storage disease in rats, a genetically determined deficiency of liver phosphorylase kinase.

Rats from an inbred strain (NZR/Mh) were found to have high concentrations of glycogen in their livers, even after 24 h of starvation. Despite this, blood glucose concentrations were well maintained on starvation for up to 72 h. The primary defect is a deficiency of liver phosphorylase kinase, causing a lack of active glycogen phosphorylase, although total phosphorylase is normal. The intravenous injection of glucagon caused a rapid activation of cyclic AMP-dependent protein kinase in the liver, but no increase in either phosphorylase kinase or phosphorylase a activity. Although total glycogen synthase activity in the livers of affected rats was higher than normal, glycogen synthase in the active form was very low, presumably as a result of the high liver glycogen content. The condition is transmitted as autosomal recessive and, apart from hepatomegaly, the affected rats appear healthy.

Animals↗