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Biomedical subjects

E Mathews

Publications and source records attributed to E Mathews.

14 recordsLinked to original sources
PubMed2000

Voltage-gated calcium channels direct neuronal migration in Caenorhabditis elegans.

Calcium signaling is known to be important for regulating the guidance of migrating neurons, yet the molecular mechanisms underlying this process are not well understood. We have found that two different voltage-gated calcium channels are important for the accurate guidance of postembryonic neuronal migrations in the nematode Caenorhabditis elegans. In mutants carrying loss-of-function alleles of the calcium channel gene unc-2, the touch receptor neuron AVM and the interneuron SDQR often migrated inappropriately, leading to misplacement of their cell bodies. However, the AVM neurons in unc-2 mutant animals extended axons in a wild-type pattern, suggesting that the UNC-2 calcium channel specifically directs migration of the neuronal cell body and is not required for axonal pathfinding. In contrast, mutations in egl-19, which affect a different voltage-gated calcium channel, affected the migration of the AVM and SDQR bodies, as well as the guidance of the AVM axon. Thus, cell migration and axonal pathfinding in the AVM neurons appear to involve distinct calcium channel subtypes. Mutants defective in the unc-43/CaM kinase gene showed a defect in SDQR and AVM positioning that resembled that of unc-2 mutants; thus, CaM kinase may function as an effector of the UNC-2-mediated calcium influx in guiding cell migration.

Amino Acid Sequence↗
PubMed1999

Splicing of alpha 1A subunit gene generates phenotypic variants of P- and Q-type calcium channels.

P-type and Q-type calcium channels mediate neurotransmitter release at many synapses in the mammalian nervous system. The alpha 1A calcium channel has been implicated in the etiologies of conditions such as episodic ataxia, epilepsy and familial migraine, and shares several properties with native P- and Q-type channels. However, the exact relationship between alpha 1A and P- and Q-type channels is unknown. Here we report that alternative splicing of the alpha 1A subunit gene results in channels with distinct kinetic, pharmacological and modulatory properties. Overall, the results indicate that alternative splicing of the alpha 1A gene generates P-type and Q-type channels as well as multiple phenotypic variants.

Alternative Splicing↗
PubMed1991

Perinatal mortality rate in a south Indian population.

Perinatal mortality rate was assessed for 13964 consecutive births in SAT Hospital, Trivandrum, South India, during a period of one year. The overall perinatal mortality rate was 42.75, stillbirth rate 24.41 and early neonatal mortality rate 18.79. The perinatal mortality rate in multiple pregnancy was 156.65. Preventable causes of perinatal mortality still make a major contribution to perinatal deaths in developing countries.

Female↗
PubMed1987

Activation of blood coagulation in Crohn's disease. Increased plasma fibrinopeptide A levels and enhanced generation of monocyte tissue factor activity.

We have examined the relationships among activation of blood coagulation, generation of monocyte procoagulant activity, and clinical activity in patients with Crohn's disease. Subclinical activation of blood coagulation was measured using a radioimmunoassay for fibrinopeptide A. Fibrinopeptide A levels were strongly correlated with the level of disease activity as measured by the Crohn's disease activity index. Patients with active disease who were successfully treated either medically or surgically demonstrated a reduction of fibrinopeptide A levels. Failure of fibrinopeptide A to return to the normal range predicted an early relapse. Monocyte tissue factor generation was assessed in both unstimulated and lipopolysaccharide-stimulated mononuclear cell cultures obtained from the peripheral blood of patients with Crohn's disease. A strong correlation (r = 0.89) was observed between plasma fibrinopeptide A levels and monocyte tissue factor generation. These results suggest that monocyte procoagulant generation may contribute to the activation of blood coagulation in this inflammatory bowel disease. Moreover, fibrinopeptide A levels in Crohn's disease may provide a useful quantitative measure of inflammatory activity.

Adolescent↗
PubMed1984

Dietary modification of fatty acid and prostaglandin synthesis in the rat. Effect of variations in the level of dietary fat.

Dietary supplements with safflower oil, linseed oil, cod liver oil and hydrogenated coconut oil were given to rats at levels of 5, 20 and 40 energy % to simultaneously assess the effects of both type and level of dietary fat on tissue fatty acid composition and prostanoid synthesis. There was no significant change in weight gain or blood pressure between the dietary groups after the 4-week dietary regimen. The liver oil and linseed oil diets depressed the arachidonic acid content of kidney phospholipids at all levels of supplementation. The arachidonic acid content of plasma lipids was significantly elevated in animals on the safflower oil diet at 20 and 40 energy % while those on the same level of liver oil diet showed a marked reduction in arachidonic acid. Whole blood synthesis of thromboxane B2 varied significantly at all levels of fat supplementation, with the 20 energy % safflower oil fed group showing maximally enhanced thromboxane B2 production compared to the coconut oil group (P less than 0.001). Conversely, the liver oil groups showed depressed thromboxane B2 synthesis at 20 and 40 energy % (P less than 0.01) compared to the coconut oil group and at 5 energy % compared to the safflower oil group (P less than 0.05). Production of 6-ketoprostaglandin F1 alpha and prostaglandin E2 by incubated kidney homogenates only differed significantly between the dietary groups at 40 energy %. Urinary excretion of 6-ketoprostaglandin F1 alpha was increased by 45% and 55% in rats fed the safflower oil diet at 20 and 40 energy %, respectively compared to the saturated fat diet, while in the liver oil groups excretion was reduced by 20% and 32%. Dietary suppression of prostanoid synthesis is explained in part by changes in available arachidonic acid and competitive inhibition of cyclooxygenase by (n - 3) fatty acids. Thus, minor changes in dietary fat can readily alter tissue fatty acid composition, but both the extent and nature of changes in phospholipid and prostanoid metabolism vary markedly according to the tissue site.

6-Ketoprostaglandin F1 alpha↗
PubMed1984

An inhibitory effect of dietary polyunsaturated fatty acids on renin secretion in the isolated perfused rat kidney.

The influence of dietary modification of polyunsaturated fatty acids (PUFA) on renin secretion, renal vascular tone and prostanoid excretion was studied in isolated perfused rat kidneys under basal conditions and in response to angiotensin II. After a four-week regimen of diets enriched with safflower oil, linseed oil or saturated fat, providing 20% of total energy intake (20 energy %), the animals which were fed linseed oil showed a significant fall in the proportion of arachidonic acid in renal phospholipids and a reduction in urinary prostaglandin excretion. In comparison with the other dietary groups, linseed oil feeding also resulted in a consistently lower renal vascular tone with increasing doses of angiotensin II. Under basal conditions both the PUFA-fed groups had significantly lower renal venous renin secretion rates relative to the saturated fat-fed control group. Infusion of angiotensin II (10 ng/min) suppressed renin secretion and abolished significant differences between the groups. As both the control group and the safflower oil group excreted similar levels of urinary prostaglandins, these results suggest that dietary enrichment with 20 energy % PUFA alters renin secretion by a prostaglandin-independent mechanism and that this may contribute to the lower blood pressures observed in these animals compared with the saturated fat-fed control group.

6-Ketoprostaglandin F1 alpha↗
PubMed1971

Role of genes 46 and 47 in bacteriophage T4 reproduction. I. In vivo deoxyribonucleic acid replication.

Functional proteins coded by genes 46 and 47 are required for (i) continuation of deoxyribonucleic acid (DNA) synthesis in the late period of T4 infection and (ii) production of normal, late replicating DNA which contains strands with a sedimentation coefficient in alkaline sucrose greater than that of mature DNA (73S). Continued DNA synthesis in the late period in the absence of functional genes 46 or 47 can be achieved by inhibiting late protein synthesis either by using bacterio-phage with a second mutation in gene 55 or by adding chloramphenicol to the culture before the decline in the rate of DNA synthesis. However, when functional 46/47 proteins are absent throughout infection, no strands with a sedimentation coefficient greater than 73S (in alkaline sucrose) are produced. This is the case even when DNA synthesis is allowed to continue. DNA arrest is accompanied by conversion of rapidly sedimenting, replicating DNA to slower sedimenting forms. When 46/47 is absent from the beginning of infection, the conversion product has a smaller sedimentation coefficient than mature DNA both in neutral and alkaline sucrose. When DNA arrest occurs midway in infection by heat-inactivating the ts46 enzyme, the conversion product has a sedimentation coefficient (i) the same as mature DNA in both neutral (63S) and alkaline sucrose if capsid assembly is allowed to take place and (ii) close to 63S in neutral sucrose but heterogenous and relatively greater (up to 100S) in alkaline sucrose if capsid assembly is inhibited. The structure of this DNA is unknown.

Centrifugation, Density Gradient↗
PubMedDate not supplied

How is your water? An interdisciplinary approach to management of biofilm in dental unit waterlines.

Much new information has become available as interest has grown in issues of biofilm formation and dental unit water quality. This interest is combined with a growing concern for occupational safety and for patients with diminished resistance. A review of recent literature spurred interest amongst the staff of The Hamilton-Wentworth Regional Public Health Department to carry out a quality audit of the dental unit water quality in clinics operated by the Department's Dental Services. Water testing was carried out, and problems with biofilm formation and water quality were identified. An interdisciplinary consultation process helped identify problems, offered possible solutions and made decisions on appropriate action to be taken. Some conservative interventions were successfully implemented even while it was recognized that more involved interventions were also needed. Repeat testing was carried out until the water quality in the clinical waterlines reached acceptable levels. Biofilm management to ensure water quality for both patients and staff, is now an integral part of quality management in the Hamilton-Wentworth Regional Dental Clinics.

Biofilms↗