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Biomedical subjects

T C Evans

Publications and source records attributed to T C Evans.

At least 55 records · Page 3Linked to original sources
PubMed1987

Nontraumatic subdural hematoma in a patient with osteogenesis imperfecta and renal failure.

Intracranial hematomas in patients with osteogenesis imperfecta rarely are reported despite an increased incidence of skull fractures. We present a case of a patient with osteogenesis imperfecta but without any history of trauma or chronic anticoagulation in whom a subdural hematoma occurred during hemodialysis. Despite operative intervention, the patient died. We could find no other cases in the medical literature of a patient with osteogenesis imperfecta who had an intracranial hematoma in the absence of a skull fracture. Patients with osteogenesis imperfecta may be at high risk for intracranial bleeding from coagulation abnormalities or otherwise trivial injuries.

Adult↗
PubMed1987

Facilitated intravenous access through local application of nitroglycerin ointment.

Thirty-four patients with diminutive peripheral veins requiring peripheral IV access (PIVA) in the emergency department setting were randomly assigned to one of two treatment groups. One group of patients (Group A) received application of a bland ointment to the dorsum of the hand prior to attempts at cannulation, while the other group (Group B) received application of 2% nitroglycerin ointment to the dorsum of the hand prior to cannulation attempts. Cannulation was achieved in all 34 patients in the study, but required significantly fewer attempts in Group B patients (P = .04). No side effects of the drug were observed in any patient or any staff member applying the ointments. We conclude that application of 2% nitroglycerin ointment to the dorsum of the hand is a safe, effective method of inducing local venodilation that will ensure PIVA with significantly fewer attempts at cannulation.

Adolescent↗
PubMed1987

The use of a drug utilisation index to monitor psychotropic drug use in hospitals.

A pilot study was undertaken to monitor the use of psychotropic drugs in a psychiatric hospital unit and a comparable acute medical unit together with their out-patient clinics, during a 2 month period. Both units served the same catchment area. Using the DDD (defined daily dose) for each class of drug, an index was calculated as an indicator of usage. An index figure of less than one indicated that each patient received on average less than the DDD, whereas an index greater than one showed that each patient received an average daily dose greater than the DDD. Other patient information collected included age, sex, length of time on drug, length of admission and the number of different psychotropic drugs received during admission.

Adult↗
PubMed1986

Morphologic determinants of coronary blood flow in the hypoplastic left heart syndrome.

The diameters of the ascending aorta, coronary ostia, and proximal coronary arteries were measured in autopsy specimens from 51 infants with hypoplastic left heart syndrome and 18 normal infant heart specimens. Standard cross sections were prepared from 35 of the hypoplastic left heart syndrome hearts, and histologic indices of myocardial viability and fibrosis were determined. The diameters of the coronary arteries and ostia in hypoplastic left heart syndrome were not different from the values in control specimens. Little fibrosis was found but extensive myocardial necrosis was present. The degree of fibrosis and necrosis did not correlate significantly with any of the arterial or ostial diameters. The extent of myocardial preservation in the hypoplastic left heart syndrome, which may substantially limit the success of surgical palliation, cannot be predicted from these morphologic measurements. The observed myocardial damage appeared to be acquired postnatally, implying that early vigorous treatment of these infants may be necessary to preserve myocardial function.

Aorta↗
PubMed1986

Effects of methyl mercury on sperm oxygen consumption.

Oxygen consumption and percent motile spermatozoa were determined for semen samples from healthy male monkeys Macaca fascicularis. Methyl mercury was added to the samples, in the oxygen measurement chamber, at a concentration of 9 p.p.m. for 15 min. and then increased to 15 p.p.m. for 15-30 min. Oxygen consumption and percent motility were determined during each period. Methyl mercury addition resulted in decreased sperm motility, but we did not detect any inhibition in the rate of oxygen consumption accompanying the decreased motility. On the contrary, the rate of oxygen consumption increased at 15 p.p.m. within 15 min., while the sperm motility was close to zero. Antimycin inhibited the increased rate of oxygen consumption demonstrating the mitochondrial source of this increased rate. Oligomycin also inhibited the increased rate of oxygen consumption due to methyl mercury, thus excluding the possibility of uncoupling of mitochondrial oxidative phosphorylation. Interference with mitochondrial energy production does not seem to be the primary mechanism of methyl mercury-induced decreased spermatozoal motility. Methyl mercury interference with the dynein/microtubule sliding assembly now seems to us to be a more tenable hypothesis.

Adenosine Triphosphate↗
PubMed1985

Pyridine nucleotide transhydrogenations in yeast.

Though previously described as very low or absent in yeast, we find significant pyridine nucleotide transhydrogenation (NADPH + acetyl pyridine-NAD+----NADP+ + acetyl pyridine-NADH) activity in yeast extracts when assayed at pH 8-9, and describe here the subcellular distribution and separation of the various molecular forms contributing to the total activity in two yeast species. Gentle subcellular fractionation reveals transhydrogenase activity only in the cytosolic fraction of both Saccharomyces cerevisiae and Candida utilis while intact mitochondria and microsomes are without activity. On sucrose gradient centrifugation, this soluble cytosolic activity proves to be primarily in a high-molecular-weight (greater than 10(6)) band which has salmon-colored fluorescence on uv illumination. Sonication of the particulate subcellular fractions solubilizes substantial transhydrogenase activity from mitochondria of C. utilis (but not from S. cerevisiae) which on sucrose gradients consists of both high (greater than 10(6))- and low-molecular-weight active fractions, each with yellow-green fluorescence. Ammonium sulfate fractionation and sucrose gradient centrifugation of protein solubilized from whole yeast of both species by vigorous homogenization with glass beads confirms the presence and fluorescence of these various molecular weight forms. The relationship of these activities to other enzymatic activities (especially the mitochondrial external NADH dehydrogenase) is discussed.

Ammonium Sulfate↗
PubMed1985

Effect of iron deficiency on energy conservation in rat liver and skeletal muscle submitochondrial particles.

Submitochondrial particles prepared from liver and skeletal muscle of control and iron-deficient rats were examined for cytochrome content and for both energy-independent and energy-conserving functions. Liver submitochondrial particles appear quite resistant to iron deficiency with cytochrome content and electron-transferring or energy-conserving functions maintained at a level of 85% or better of normal. Iron-deficient skeletal muscle submitochondrial particles, in contrast, have decreased cytochrome content and only 15-20% of the normal capacity for oxidation through either complex I (NADH dehydrogenase) or complex II (succinate dehydrogenase). Energy-linked reactions which involve substrate oxidation/reduction (succinate----NAD+ reversed electron flow and succinate-driven energy-dependent transhydrogenation) are likewise markedly decreased, while ATP-driven energy-dependent transhydrogenation and mitochondrial ATPase are normal. Our data support the concept that iron deficiency leads to decreased electron-carrying capacity of iron-containing mitochondrial enzymes, with skeletal muscle being much more susceptible than liver, but that the mitochondria are otherwise normal with regard to energy conservation.

Adenine Nucleotides↗
PubMed1984

Sensitivity to retinal defocus with aspheric soft lenses--predictions and clinical validation.

The purpose of this study was to obtain a numerically accurate discrete model of the effect of front aspheric soft lenses of various asphericities on the retinal illuminance profiles within the blur circles of a model eye. A computer program was developed for a model eye based on geometrical optics. The ray density was assumed to be proportional to the flux density or illumination. Retinal illuminance profiles are calculated for several values of defocus and asphericity. These results are validated by calculations based on modulation transfer functions (MTFs), observational data from contrast sensitivity and clinical results with Cals aspheric soft lenses. The results suggest that aspheric soft lenses maximize the central illuminance of blur circles and extend the range of desensitivity to retinal defocus in the eye to 4.00 D at the largest asphericity constant investigated.

Contact Lenses, Hydrophilic↗
PubMed1975

Blood pressure changes in mice after lethal staphylococcal infection and endotoxin challenge.

A radioisotope technique has been used to determine blood pressure changes in mice after lethal staphylococcal infection and after lethal endotoxin challenge. The method was verified by making simultaneous direct measurements in rats. Mice in both groups became hypotensive to a similar level (a fall 20-30 mm Hg). This tailcuff technique is simple and reliable but is dependent upon normal tail blood flow. Spurious low pressure readings are obtained in hypothermic or chilled mice because the tail is a major thermoregulator organ. These difficulties can be overcome by warming chilled or hypothermic mice.

Animals↗