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Biomedical subjects

C Ward

Publications and source records attributed to C Ward.

At least 199 records · Page 11Linked to original sources
PubMed1987

Comparison of epidural pressure in live anesthetized and post-mortem primates.

The response of the head to impact in the posterior-to-anterior direction was investigated with live anesthetized and post-mortem primates. The study was conducted at the University of Michigan Transportation Research Institute (UMTRI) under the sponsorship of the Motor Vehicle Manufacturers Association. 3-D motion and epidural pressures were experimentally measured. Interpretation of the results by simulating the tests using a 3-D mathematical model of the primate brain was done by Dr. C. Ward. The results of the tests and the simulation are presented to demonstrate the differences found between live and post-mortem primate brains.

Animals↗
PubMed1986

Mechanism of the inhibitory effect of trifluoperazine on isoprenaline-evoked amylase secretion from isolated rat parotid glands.

We have investigated the effects of the calmodulin antagonist trifluoperazine (TFP) on amylase secretion and adenosine 3':5'-monophosphate (cyclic AMP) metabolism using incubated parotid glands of young rats. Exposing unstimulated glands to 100 microM TFP doubled the basal rate of amylase and lactate dehydrogenase (LDH) release, but had no effect on either the parotid cyclic AMP or ATP contents. Isoprenaline (1 microM) stimulated amylase secretion and increased the tissue cyclic AMP content. 100 microM TFP inhibited these responses by 46% and 33%, respectively. N6,O2-dibutyryl adenosine 3',5'-monophosphate (dibutyryl cyclic AMP) mimicked the effect of isoprenaline on amylase release but 100 microM TFP had no effect on this response. 10 microM TFP inhibited F- -stimulated adenylate cyclase activity in a subcellular fraction isolated from the parotid by 32%. We conclude that TFP may inhibit isoprenaline-evoked amylase secretion from the rat parotid by an effect on either the catalytic or regulatory subunits of adenylate cyclase.

Adenylyl Cyclases↗
PubMed1986

The search for volumetric symmetry in reconstruction of the breast after mastectomy.

The difficulty in achieving volumetric symmetry in the course of reconstruction of the breast after mastectomy is emphasised. The published methods of estimating breast volume are outlined before describing a new apparatus relying on the displacement of air within a large calibrated cylinder and which, by objective and clinical evaluation, has proved to be gratifyingly accurate. The method of achieving symmetry is illustrated in a patient originally referred with an inadequate breast mound reconstruction.

Breast↗
PubMed1986

Pulmonary veno-occlusive disease. A report of four cases.

Four cases of pulmonary veno-occlusive disease are described. Two patients, who were brothers, had respiratory tract infections. The third patient had chronic active hepatitis and coeliac disease suggesting an abnormality of the immune system; the fourth patient had no obvious cause but presented initially with systemic hypertension. Three of the cases had been diagnosed initially as primary pulmonary hypertension either on open lung biopsy or clinically. In all cases the pulmonary arteries were abnormal with medial hypertrophy, intimal fibrosis and, in some cases, thrombosis in elastic pulmonary arteries. These findings suggest that pulmonary veno-occlusive disease is not confined to veins and should be considered as a widespread pulmonary vascular disease. The range of aetiological factors indicate that it should not be considered as a single disease entity.

Adolescent↗
PubMed1986

A case-control study of twin pairs discordant for Parkinson's disease: a search for environmental risk factors.

A previous study of twins with Parkinson's disease (PD) revealed low concordance, suggesting that genetic factors play a minor role in the etiology of PD. To identify possible environmental determinants of PD while maximally controlling for hereditary factors, 31 monozygotic twin pairs discordant for PD were interviewed by telephone. Information about possible risk factors was obtained from systematic and uniform interviews with cases and controls. The only statistically significant result was less cigarette smoking by PD patients (p less than 0.05). Thirteen dizygotic discordant twin pairs were evaluated with the same techniques, but there were no statistically significant differences between affected and unaffected twins.

Female↗
PubMed1985

Smoking and coronary artery disease assessed by routine coronary arteriography.

The association between extent and duration of smoking habit and severity of coronary atheroma was examined in 387 patients undergoing routine coronary ateriography before valve replacement surgery. Total number of cigarettes smoked in life correlated significantly with severity of coronary artery disease (p less than 0.001) and number of coronary arteries with stenoses of 50% or more (p less than 0.001). Severity of coronary artery disease in current smokers was similar to that in former smokers. Multiple regression analysis showed diastolic blood pressure, cigarette consumption, age, ratio of total cholesterol to high density lipoprotein cholesterol, and history of angina to be the important predictors of severity of coronary artery disease. An estimate of the number of cigarettes smoked in life can be useful in identifying patients with coronary artery disease if used in conjunction with data on other important risk factors.

Arteriosclerosis↗
PubMed1985

The use of thick split thickness grafts from the instep in paediatric hand surgery.

In skin grafting the hand restoration of function must always be the priority, but an acceptable appearance is also important and care should be taken in selecting a skin graft that matches the recipient site. The disadvantages of some traditional donor sites are outlined. A clinical study of thick, split-thickness grafts from the instep is described from which it is concluded that a good aesthetic result can be achieved without compromising hand function--but only in children and adolescents among whom there was no donor site morbidity.

Adolescent↗
PubMed1984

DNA methylation. Inhibition of de novo and maintenance methylation in vitro by RNA and synthetic polynucleotides.

A partially purified HeLa cell DNA methylase will methylate a totally unmethylated DNA (de novo methylation) at about 3-4% the rate it will methylate a hemimethylated DNA template (maintenance methylation). Our evidence suggests that many, if not most, dCpdG sequences in a natural or synthetic DNA can be methylated by the enzyme. There is a powerful inhibitor of DNA methylase activity in crude extracts which has been identified as RNA. The inhibition of DNA methylase by RNA may indicate that this enzyme is regulated in vivo by the presence of RNA at specific chromosomal sites. The pattern of binding of RNA to DNA in the nucleosome structure and the DNA replication complex may determine specific sites of DNA methylation. An even more potent inhibition of DNA methylase activity is observed with poly(G), but not poly(C), poly(A), or poly(U). The only other synthetic polynucleotides studied which inhibit DNA methylation as well as poly(G) are the homopolymers poly(dC).poly(dG) and poly (dA).poly(dT). These results point out the unique importance of the guanine residue itself in the binding of the DNA methylase to dCpdG, the site of cytosine methylation. The surprising inhibition of the methylation reaction by poly(dA).poly(dT), which is itself not methylated by the enzyme, suggests the possible involvement of adjacent A and T residues in influencing the choice of sites of methylation by the enzyme.

Cell Nucleus↗
PubMed1984

Control of Herpes simplex virus thymidine kinase gene expression in Saccharomyces cerevisiae by a yeast promoter sequence.

This study presents the first evidence that the 5' promoter region of the Saccharomyces cerevisiae glyceraldehyde-3-phosphate dehydrogenase gene (G-3-PD) promoter will permit expression of an adjacent foreign gene. The S. cerevisiae G-3-PD promoter was linked to the herpes simplex virus--thymidine kinase (HSV-TK) gene in a shuttle plasmid capable of autonomous replication in both yeast and Escherichia coli. Since the HSV-TK gene promoter is not functional in yeast, yeast cells containing these plasmids will express the HSV-TK gene and synthesize thymidine kinase only if the yeast promoter fragment is fused to the HSV-TK gene in the proper orientation. The 5' flanking sequences necessary for the expression of heterologous eukaryotic genes in S. cerevisiae are discussed.

Base Sequence↗
PubMed1984

Angina, coronary risk factors and coronary artery disease in patients with valvular disease. A prospective study.

The relationship between coronary risk factors and coronary artery disease in patients with valvular heart disease was studied prospectively in 387 consecutive patients undergoing routine coronary arteriography prior to valve replacement. Coronary artery disease was as common in patients with mitral valve disease (31.9%) as in those with aortic valve disease (26.8%). Although it occurs more frequently in patients with angina (45.7%) significant coronary artery disease is found in 19.2% (47 of 245) of those without angina (P less than 0.001), suggesting that the presence of angina alone is an unreliable indicator of significant coronary disease. The prevalence and severity of significant coronary artery disease increases progressively as the number of coronary risk factors also increase (P less than 0.001) but the prevalence is low (3%) in patients in whom both angina and coronary risk factors are absent. These findings suggest that preoperative coronary arteriography might be omitted in this latter group of patients.

Adolescent↗
PubMed1984

Ergogenic demands of a 24 hour cycling event.

The maximal aerobic performance (VO2 max) and energy costs of cycling at various power outputs and equivalent road speeds of a highly trained endurance cyclist (age 23.4 yrs, height 1.95 m, weight 73.1 kg), were measured in the laboratory on an eddy-current cycle ergometer, and the physiological responses related to determinations made during a 24 h cycling time trial event, using continuous ECG recording from which estimates of ergogenic demands were obtained. The cyclist covered a distance of 694 km during the event at an average speed of 28.9 km.h-1 which corresponded to an equivalent oxygen cost of 38.5 ml.kg-1 min-1 and represented approximately 55% of his VO2 max. During the event, the cyclist expended an estimated 82,680 kJ of energy, of which approximately 44,278 kJ (54%) were supplied by repeated feedings of liquids, solids and semi-solids and some 38,402 kJ (46%) came from the stored energy reserves which resulted in a 1.19 kg loss of body weight during the event. The energy demands of the activity were more than three times greater than the highest recorded values of severe industrial work, and similar to the hourly rates of expenditure of shorter duration competitive events, but above the highest values reported over other extreme endurance events over the same period of time. The results thus represent near maximal levels of sustainable ergogenic effort by man over a complete 24 h cycle.

Adult↗
PubMed1984

An evaluation of the one-day NBT-PABA/14C-PABA in the assessment of pancreatic exocrine insufficiency.

The one-day NBT-PABA/14C-PABA has been performed on 58 consecutive subjects with suspected or established pancreatic disease. 23 of these were normal subjects, 12 were subsequently shown to have other gastrointestinal disease and 23 had proven pancreatic disease. A PABA excretion index (PEI) has been calculated and, using our lower limit of normality (0.61), the test has shown an overall sensitivity of 83% and specificity of 89%. False positives were a particular problem in the other gastrointestinal disease group (25%). There was a close correlation between PEI and Lundh mean tryptic activity (r = 0.89). These results indicate that this test is a satisfactory screening test for pancreatic exocrine disease and is easier to perform with less likelihood of error than many other non-invasive tests of pancreatic function.

4-Aminobenzoic Acid↗
PubMed1984

The significance of changes in blood lymphocyte populations following surgical operations.

After surgery blood lymphocyte levels fell to one-third of the pre-operative value. Since this depression was transient, and followed the peak of serum cortisol closely, it was probably due to a redistribution of lymphocytes from the blood to the tissues. The proportion of activated lymphocytes, as measured by the incorporation of 3H-thymidine in vitro without added mitogen, was substantially increased about 5-8 days after operation. The greatest number of S-phase lymphocytes was found after operation combined with blood transfusion but surgery alone and blood transfusion alone each produced significant increases. The proportions of B lymphocytes, T helper cells and T suppressor cells remained nearly constant despite the fluctuations in total lymphocyte counts. The response of lymphocytes in vitro to phytohaemagglutin (PHA) was doubled on average 7 days after surgery provided the test was performed in the patient's own serum. In pooled serum there was no consistent change in the response to PHA. It is argued that none of the observed changes necessarily signify that a phase of immunosuppression follows surgical operations.

Blood Transfusion↗
PubMed1983

A microcolorimetric assay of inorganic pyrophosphatase.

A procedure is described for the assay of inorganic pyrophosphatase in tissues by a microcolorimetric procedure, taking advantage of the marked color intensification of phosphomolybdate by malachite green. Conditions are described for optimum enzyme activity, color stability, and sensitivity. With 1-cm cuvettes the AM660 is 100,000, allowing accurate measurement of Pi in the 1-nmol range. Reaction is conducted at 25 degrees C for 10 min in 0.5 ml of a 50 mM histidine buffer, pH 7.2, containing 0.2 mM inorganic pyrophosphate and 4 mM Mg2+, terminated by addition of 0.05 ml 2.4 M HClO4, cooled in ice, and 0.45 ml of color reagent is added. After standing 10 min at 0 degrees C, the contents are transferred to 1-cm cuvettes and the absorbance is read at 660 nm. Blanks are low, nonenzymatic hydrolysis of PPi is negligible, and color is stable without addition of detergents. The high sensitivity makes this procedure well-adapted to measurement of optimal activities in crude tissue preparations.

Animals↗