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Biomedical subjects

C Howard

Publications and source records attributed to C Howard.

At least 73 records · Page 4Linked to original sources
PubMed1988

Fibrin seal adhesive versus nonabsorbable microsuture in peripheral nerve repair.

Although nonabsorbable microsuture is the material most often used in human peripheral nerve repair, it is capable of eliciting a foreign body reaction, impairing vascularity, and potentially disrupting axonal regeneration. Sutureless methods, including fibrin seal adhesive, may offer an alternative to traditional suture techniques. This study compared the efficacy of fibrin seal with nylon microsuture in tibial microneurorrhaphy on 28 adult New Zealand white rabbits (14 with 10-0 monofilament nylon suture and 14 with fibrin seal). Each rabbit was reexplored at 1, 6, 12, and 18 weeks. The criteria used to compare the two methods were operative time, clinical function, electrophysiologic measures, and histologic findings. Fibrin seal repairs required less time to execute (p less than 0.01) but were inferior in mean conduction amplitude (p less than 0.01) and with respect to histologic criteria. Fibrin seal also appeared less effective in maintaining nerve approximation. We do not believe that fibrin seal provides a superior alternative to nonabsorbable suture in primary nerve repair in this experimental model.

Animals↗
PubMed1988

The management of congenital dislocation of the hip in the newborn.

We describe the results of a policy of highly selective splintage for CDH, using knee plasters. No child suffered because splintage was withheld. In those who were treated the results were satisfactory and the proportion who required a subsequent operation was extremely low. Avascular necrosis was not a significant problem. The method, although a little more time consuming, appears to offer significant advantages over current alternatives.

Hip Dislocation, Congenital↗
PubMed1987

Violence in sleep: medico-legal issues and two case reports.

Reported cases of violence during sleep are reviewed. Two new cases are reported where the subjects were charged respectively with attempted murder and murder; both were acquitted on the grounds of non-insane automatism. Clinical features and aetiological factors are analysed. The legal concepts surrounding non-insane automatism are discussed and criticized.

Adolescent↗
PubMed1987

Linear nevus sebaceous syndrome. A review.

We report a case of linear nevus sebaceous syndrome with large areas of calcification involving multiple layers of the posterior aspects of both eyes. This patient had a normal neurological examination despite dysplastic brain changes. We discuss and review the multiple clinical presentation and embryopathogenesis of this disorder.

Calcinosis↗
PubMed1985

The role of high levels of dietary fat in 7,12-dimethylbenzanthracene-induced mouse mammary tumorigenesis: lack of an effect on lipid peroxidation.

The effects of dietary fat on 7,12-dimethylbenzanthracene (DMBA)-induced mammary tumorigenesis were examined in BALB/c female mice. In the first experiment, BALB/c mice were treated with a total dose of 1, 3, or 6 mg DMBA to induce mammary tumors. One week after the last dose of DMBA, the mice were placed on a 5% (LF) or 20% (HF) corn oil semi-purified diet. The 20% corn oil diet resulted in a significantly decreased mean tumor latency period in each of the three groups of mice (p less than 0.05). However, the mammary tumor incidences at 11 months after DMBA treatment were the following: 6 mg DMBA (LF-14/32, HF-17/32); 3 mg DMBA (LF-13/50, HF-14/50); 1 mg (LF-2/50, HF-6/50). In the second experiment, prolonged hormonal stimulation by pituitary isografts, but not a HF diet, enhanced the incidence of mammary tumors in BALB/c mice given a threshold dose of DMBA (0.5 mg). In a further attempt to examine the mechanism of the enhancing effects of dietary fat, lipid peroxidation was measured in the microsomal-mitochondrial fractions of the mammary glands by two assays; measurements of conjugated dienes and TBA reactants (malonyldialdehyde). The high fat diet had no effect on the levels of conjugated dienes in mammary cell membrane preparations and decreased the levels of TBA reactants (malonyldialdehyde). The results indicated that a high fat diet did not lead to enhanced levels of lipid peroxidation in preparations of microsomal mitochondrial membranes from mouse mammary glands. The implications of these results are discussed with respect to the role of dietary fat as a promoter of mouse mammary tumorigenesis.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1984

Natural frequency of fracture fragments in the assessment of tibial fracture healing.

The natural frequency of fracture fragments has been measured at various times in the course of healing of 11 midshaft tibial fractures. The major fragments manifest different frequencies which are themselves distinct from that of the intact bone. It has been shown that the difference in frequency between the major fragments falls with time, so that the separate frequencies approach a common value which corresponds with the healed state. The results have been used to construct a model healing curve, against which other tibial fractures can be compared.

Adolescent↗
PubMed1984

Increased leucine flux in short-term fasted human subjects: evidence for increased proteolysis.

Plasma leucine concentration increases with short-term fasting in normal humans. In previous studies using an 18-h constant infusion of [2H3]leucine, a 15% decrease in the rate of appearance (Ra) of leucine was observed between 15 and 30 h of fasting. However, incorporation of labeled leucine into and subsequent release from body protein could result in an apparent decrease in leucine Ra. The present studies were undertaken to determine the rate of leucine N and carbon flux in short-term fasted human subjects in using an experimental design that would minimize potential recycling of label. Six normal subjects were infused with [15N]- and [2H3]leucine for two 4-h periods (0600 to 1000 h and 2000 to 2400 h) during a 30-h fast. Between the 15th and 30th h of fasting, plasma leucine concentration (102 +/- 10 to 169 +/- 18 microM, P less than 0.01) and leucine C (1.46 +/- 0.05 to 1.64 +/- 0.10 mumol X kg-1 X min-1, P less than 0.05) and leucine N (1.93 +/- 0.14 to 2.49 +/- 0.26 mumol X kg-1 X min-1, P less than 0.05) flux increased, whereas the metabolic clearance rates of leucine C and N decreased (P less than 0.01 and less than 0.05, respectively). Therefore, when isotope recycling is minimized with short periods of isotope infusion, leucine flux increases between 15 and 30 h of fasting. Because the only source of leucine in the postabsorptive periods is body protein, we conclude that the rate of whole-body proteolysis is increased in short-term fasting in humans.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Glucose production and utilization in children with glycogen storage disease type I.

Glucose turnover rates were estimated with [2H2]glucose in five children with glycogen storage disease type I (GSD I) during sequential withdrawal of an infusion of glucose to determine whether their hypoglycemia was the result of decreased glucose production or increased rates of glucose utilization. Plasma glucose concentrations were 78 +/- 5 mg/dl during infusion of glucose at 6 mg X kg-1 X min-1 and decreased to 53 +/- 3 and 45 +/- 7 mg/dl during the 3 and 1.5 mg X kg-1 X min-1 glucose infusions, respectively. Total glucose flux during the 6 mg X kg-1 X min-1 glucose infusion was 7.3 +/- 0.7 mg X kg-1 X min-1 and decreased with reduction in the rate of glucose infused. Endogenous glucose production increased with each decrease in the rate of exogenous glucose infused. Following discontinuation of glucose infusion, endogenous glucose production was 3.9 +/- 0.3 mg X kg-1 X min-1, a value that was lower (P less than 0.05) than that observed in overnight-fasted normal children (6.3 +/- 0.3 mg X kg-1 X min-1) but not statistically different from the Ra of normal children fasted for 30 h (4.1 +/- 0.5 mg X kg-1 X min-1). Thus, children with GSD have glucose production rates that are 40% lower than those of normal children fasted overnight but equal to those of normal children fasted 30 h. Rates of glucose utilization during the 6 mg X kg-1 X min-1 glucose infusion were higher (0.05 less than P less than 0.1) than those of overnight-fasted normal children, despite lower plasma glucose concentrations when expressed on a body weight basis but not when expressed on the basis of estimated brain weight.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Hydroxybutyric Acid↗
PubMed1983

Effects of ketosis on glucose flux in children and adults.

Sequential glucose flux studies were carried out in five normal and six epileptic children and ten adult volunteers using [6,6-2H2]glucose to determine the effect of ketosis on carbohydrate homeostasis in children and adults. All subjects were studied after 14 and 30-38 h of fasting while consuming a normal diet and the epileptic children under 14 h of fasting while consuming an isocaloric ketogenic diet (75% fat wt/wt). Glucose flux, when expressed per kilogram body weight, was inversely correlated with the degree of ketosis in children (P less than 0.001) and in adults (P less than 0.01), but not when both children and adults were considered together (r = 0.078). When glucose flux was corrected for estimated brain weight, the relationship between glucose flux and ketonemia was linearly related in children (P less than 0.001), in adults (P less than 0.02), and when all subjects were considered together (P less than 0.001). The inverse relationship between ketonemia and glucose flux corrected for estimated brain mass is consistent with a partial replacement of glucose by ketone bodies for cerebral metabolism and may provide a more rational means of expressing glucose flux data to take into account the higher brain-to-body ratio in children.

Acidosis↗