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Biomedical subjects

G Burns

Publications and source records attributed to G Burns.

66 records · Page 4Linked to original sources
PubMed1984

Long-term follow-up of pulse width threshold of transvenous and myo-epicardial leads.

Postoperative pulse width thresholds were measured at a constant of 5 volts in 140 patients. In 41 patients, transvenous atrial and/or ventricular leads were implanted at a median age of 13 years (3-78 yrs). Myo-epicardial leads were implanted in 99 patients at a median age of 8 3/4 years (1 wk to 76 yrs). The initial rapid rise of threshold was found to persist not longer than to the third follow-up period of 11 days to 5 weeks in all atrial and transvenous ventricular leads; in myo-epicardial ventricular leads it persisted until the period of more than 5 weeks to 6 months. During initial rise, pulse width threshold m + sem did not exceed 0.45 ms. We therefore suggest that a pulse width setting of 0.5 ms at 5 V is a safe setting for this period. In only one patient did a late rise of threshold occur. The comparison of pulse width thresholds of transvenous versus myo-epicardial leads showed lower mean values for transvenous atrial leads in each follow-up period, but the difference was not statistically significant. The pulse width thresholds of transvenous ventricular leads were significantly lower than those of myo-epicardial leads in some follow-up periods. We therefore conclude that transvenous leads have a slight advantage with regard to postoperative pulse width threshold.

Adolescent↗
PubMed1983

The blood sex hormone levels in sexually mature male atlantic salmon (Salmo salar) in the Westfield River (pH 4.7) and the Medway River (pH 5.6), Nova Scotia.

Blood samples were taken from fourteen sexually mature (ripe) male Atlantic salmon (Salmo salar), eight from the acidic Westfield river (pH 4.7) and six from the less acidic (pH 5.6) Medway river to determine if there is any difference in sex hormone production in the fish in the two rivers. The plasma levels of the two principal male sex hormones, testosterone and 11-ketotestosterone, which normally peak at functional sexual maturity, were significantly lower in salmon from the more acidic Westfield river compared to those in salmon from the Medway river. Since these fish were of the same stock, and were in the same state of sexual maturation, it is suggested that the more acidic Westfield River has affected the production and/or utilization of sex hormones in this species.

Animals↗
PubMed1983

Comparison of electrophoretic isoamylase patterns among various species.

The electrophoretic pattern of isoamylase in the serum, urine, pancreas, salivary gland, liver, and small intestine of the dog, pig, rat, hamster, and prairie dog was compared to man. Great species variation in isoamylase patterns was noted. These variations should be kept in mind when studying pancreatic disease in species other than man. It is of interest that the serum and urine isoamylase of the prairie dog was most similar to that of man.

Amylases↗
PubMed1983

Effects of amino acid infusions on cell metabolism in hemodialyzed patients with uremia.

Eighteen uremic patients received i.v. infusions of a mixture of amino acids three times per week for 3 months in an effort to improve cellular amino acid imbalance and related cell bioactivities. They were a subset of 42 uremic patients stabilized by maintenance hemodialysis and were characterized by reduced cellular levels of threonine, isoleucine, methionine, and ornithine, with increased levels of aspartate, glycine, arginine, tyrosine, and phenylalanine. Protein synthesis (3H-leucine incorporation), energy level [energy charge = (ATP + 1/2 ADP)-(ATP + ADP + AMP)], and activity of the rate-limiting glycolytic enzyme pyruvate kinase were reduced in these patients compared with 32 control normal subjects. The circulating leukocyte (88 +/- 5% granulocytes) was used as a cell model. Previously, multiple regression best-subset analysis showed that a combination of the cell levels of aspartate, valine, isoleucine, ornithine, lysine, and tryptophan could "explain" 40% of the variance in protein synthesis in these patients. Similarly, a combination of the levels of aspartate, glutamic acid, glycine, ornithine, and arginine were "predictive" of the level of energy charge. We hypothesized that protein synthesis and energy level would be improved if the amino acid infusions normalized the intracellular levels of those amino acids that were predictive of the bioactivities. After 3 months of amino acid infusions, levels of the predictive intracellular amino acids were not improved, but deviated further from baseline values. Failure to detect significant improvement in the cell bioactivities is attributed to inability to correct the imbalance in the intracellular amino acid pool.

Amino Acids↗
PubMed1977

Fetal malnutrition: an appraisal of correlated factors.

Fetal malnutrition has emerged as a significant health problem over the past decade. Present evidence suggests that maternal environment plays the major etiologic role in fetal malnutrition. The association of fetal malnutrition in mothers with chronic hypertension is well known, but fetal malnutrition is associated with maternal hypertension in less than 25 per cent of cases. Among a group of 182 pregnant women studied at midpregnancy for blood levels of vitamins, trace metals, proteins, amino acids, and parameters of maternal leukocyte energy metabolism, it was found that the concentration of 10 amino acids, alpha-1-globulin, zinc, and total carotenes had a statistically significant relationship to fetal growth. Similarly significant correlations were found for maternal leukocyte adenosine disphosphate, phosphofructokinase activity, ribonucleic acid (RNA) synthesis, and cell size. Maternal cigarette smoking was correlated with reduced fetal growth. Analysis showed that there was a significant reduction in leukocyte RNA synthesis and phosphokinase activity and in the plasma levels of 14 amino acids, and carotene in smoking mothers. This information lends support to the hypothesis that factors which affect the growth of fetal cells also will affect maternal leukocytes in a definable way.

Adolescent↗
PubMedDate not supplied

Complications common to ventricular assist device support are rare with 90 days of DeBakey VAD support in calves.

The DeBakey VAD is a miniaturized, electromagnetically driven axial flow pump intended for long-term ventricular assist. Safety and performance data from six calves implanted with the complete DeBakey VAD system are reported elsewhere; here we describe complications and necropsy findings for these same six animals, all of which survived 90 days. The study was conducted according to a uniform protocol, which included anticoagulation and antibiotic prophylaxis. Clinical complications tracked included bleeding, cardiovascular abnormalities (e.g., arrhythmias, tachycardia unrelated to pain, bradycardia), hemolysis, hepatic dysfunction, renal dysfunction, thromboembolism (neurologic or peripheral), or infection. Each adverse event was retrospectively categorized with regard to severity (mild, moderate, severe) and relationship to device. Clinical findings were confirmed by necropsy. There was no evidence of systemic infection, thromboembolism, hemolysis, or renal or hepatic dysfunction in these six animals during the study period. A single adverse event was noted in each of two of the calves. Both events were considered mild according to the predefined criteria. Bleeding related to the surgical implantation procedure and requiring reoperation occurred in one animal. The other animal had evidence of a superficial infection at the exit site of the cables on the left lateral thoracic wall; the infection did not extend into the thoracic cavity. Chronic, healed small renal infarct scars were present in several animals. Mild valvular endocardiosis was observed in two calves and mild fibroelastosis was present in the endocardium at the site of the inflow cannula in three calves; however, these lesions were not considered clinically significant. No other gross or histologic abnormalities were noted at necropsy. In conclusion, calves implanted with the complete DeBakey VAD for 90 days demonstrated few complications and had no significant necropsy findings. Complications common to ventricular assist device (VAD) support (i.e., hemolysis, infection, bleeding, thromboembolism) were rare during long-term support (90 days) with the DeBakey VAD.

Animals↗
PubMedDate not supplied

In vitro adherence of bacteria to sutures in cardiac surgery.

The adherence of bacteria to sutures used in cardiac surgery was studied by in vitro quantitative determination with [3H]-leucine-labeled Staphylococcus epidermidis, Staphylococcus aureus and Streptococcus sanguis. The adherence per unit area for staphylococci was least for monofilament polypropylene (Prolene), 3 times higher (p less than 0.05) for braided polyester (Mersiline) and greatest (10 times, p less than 0.005) for braided polyester sutures coated with polybutylate (Ethibond). Mean values for the adherence of streptococci were low for all the sutures. Sutures pretreated with human plasma showed a 12-37% increase in bacterial adherence. The cell surface hydrophobicity, surface charge and the haemagglutinating property of bacteria did not correlate with their adherence property. In view of these observations, it is suggested that: (a) the preferential adherence of staphylococci to intra-cardiac sutures may be one of the explanations for its being the commonest cause of early prosthetic valve endocarditis, (b) there is a need for a careful selection of sutures used in cardiac surgery and (c) the described in vitro assay for bacterial adherence may be used for monitoring the development of better designed sutures and the effect of incorporation of antibiotics in the sutures.

Bacterial Adhesion↗
PubMedDate not supplied

Determination of ethyl carbamate in alcoholic beverages and soy sauce by gas chromatography with mass selective detection: collaborative study.

A method using gas chromatography with mass selective detection for the determination of ethyl carbamate (EC; also known as urethane) in alcoholic beverages and soy sauce was collaboratively studied by 17 laboratories including authors' laboratories. The method uses prepacked columns for extraction of liquids with methylene chloride, and n-propyl carbamate as the internal standard. A practice sample and 6 samples of distilled spirits, fortified wines, table wines, and soy sauces were analyzed by each collaborator. Each matrix included blind duplicates of incurred and fortified EC at 3 levels. Distilled spirits contained 50-330 ng EC/g (ppb), fortified wine 40-160 ppb, table wine 10-50 ppb, and soy sauce 15-70 ppb. The ranges of the repeatability relative standard deviations, excluding outliers, were 4.03-6.63% for distilled spirits, 4.01-5.05% for fortified wine, 3.94-6.73% for table wine, and 4.70-8.49% for soy sauce. The ranges of the reproducibility relative standard deviations, excluding outliers, were 8.53-9.49% for distilled spirits, 6.84-12.02% for fortified wine, 8.86-18.47% for table wine, and 13.87-27.37% for soy sauce. Recoveries of added EC ranged from 87 to 93%. Recoveries relative to reference values, labeled as the internal standard, obtained by using gas chromatography/tandem mass spectrometry with a triple quadrupole mass spectrometer ranged from 89 to 100%.

Alcoholic Beverages↗