Search PubMed⌕ Search

Biomedical subjects

G M Briggs

Publications and source records attributed to G M Briggs.

At least 37 records · Page 2Linked to original sources
PubMed1986

Electrophysiological properties of cultured adult rat ventricular cardiac muscle cells.

Action and resting potential characteristics of isolated adult rat myocardial cells maintained in culture for 10-28 days are described. Resting potentials averaged -76.3 +/- 2 mV in 5 mM extracellular [K+] ([K+]o). Resting potentials changed by 54.3 mV/decade change in [K+]o for concentrations greater than 5 mM. The average maximum rate of rise of action potential (Vmax) was 117.7 +/- 10 V/s with overshoots of 34.6 +/- 2.5 mV. Action potential durations (APD) to 0 and -40 mV and full repolarization were 21.8 +/- 3.9, 36.3 +/- 6.0, and 206 +/- 16.9 ms respectively. Action potential configurations were qualitatively similar to those previously reported by others for rat myocardial tissue or freshly dissociated cells. Tetrodotoxin (4 micrograms/ml) decreased Vmax to less than 24 V/s and decreased overshoot and APD. Isoproterenol (10(-8) M) decreased APD with slight elevation of the overshoot. Verapamil (10(-5) to 10(-4) M) depressed overshoot and plateau while slowing the final phase of repolarization. Verapamil (10(-4) M) depressed upstroke velocity and blocked excitability. While APDs recorded from these cultured cells are apparently longer than those reported by others for rat myocardial APDs, the values of all other electrophysiological parameters recorded are within the limits previously reported for normal rat myocardial tissue. These data indicate that adult rat myocardial cells maintained in tissue culture for 10-28 days possess electrophysiological properties and responses to pharmacological agents similar to adult rat myocardial tissue or undamaged freshly isolated cells.

Action Potentials↗
PubMed1984

Decrease in bone density in young male guinea pigs fed high levels of ascorbic acid.

These experiments were conducted to investigate the effects of high oral intakes of ascorbic acid on bone metabolism in young guinea pigs and to inquire into the mechanism mediating these effects. Male guinea pigs 14 days old fed 8.7% of ascorbic acid for 6 weeks had decreased bone density and decreased urinary hydroxyproline compared to control animals fed 0.2% of ascorbic acid. To assess whether these changes were due to the acidity of the diet or to vitamin activity, salts of ascorbic acid, salts of erythorbic acid and free erythorbic acid were fed. There were no significant bone changes in any of these groups. The results strongly indicate that the acidity of ascorbic acid plays a part in the decrease in bone density but do not rule out that some other metabolic property specific to ascorbic acid may also be implicated.

Aging↗
PubMed1983

Contrast agent-induced thrombophlebitis following leg phlebography: meglumine loxaglate versus meglumine lothalamate.

A comparison was made of the incidence of venous thrombophlebitis resulting from the use of a high-osmolality contrast medium (Conray 60%, meglumine ioxaglate) and a low-osmolality contrast medium (Hexabrix 59%, meglumine iothalamate). In 30 patients with varicose veins, Conray was injected into one leg and Hexabrix into the other. The incidence of thrombophlebitis was then determined using the iodine-125 fibrinogen uptake test in a prospective, randomized, double-blind study. There was significantly less thrombophlebitis with Hexabrix than with Conray and the authors conclude that Hexabrix is safer for phlebography. Hexabrix is also stable in solution, only slightly more expensive than Conray, and one fifth the cost of metrizamide.

Adult↗
PubMed1983

Iohexol and meglumine iothalamate in phlebography of the leg. Comparison of the tolerance.

Fifty patients were examined by ascending phlebography of both legs in a prospective, double blind, within-patient series. Each leg was randomly allocated to the examination using either iohexol 300 mg I/ml or meglumine iothalamate 280 mg I/ml as the contrast medium. Immediate side effects were recorded in all patients, and delayed effects in 45 patients. Statistical analysis using the chi-square test showed that iohexol produced significantly less immediate pain in the leg than meglumine iothalamate. Iohexol produced significantly less nausea, and vomiting during the injection than meglumine iothalamate. No significant difference was found in the incidence of delayed pain and swelling with either medium. The quality of the films produced by iohexol was significantly better than that obtained with meglumine iothalamate.

Adult↗
PubMed1982

Comparison of tri-iodoisophthaldiamide with meglumine lothalamate in phlebography of the leg.

One hundred patients were examined by ascending phlebography of both legs in a prospective, double-blind, within-patient study. Each leg was randomly allocated to the examination using either lopamidol 61% as the contrast medium. Immediate side effects were recorded in all patients, and delayed effects in 46 patients. Statistical analysis using the chi-square test showed that lopamidol produced significantly less immediate and delayed pain in the foot and the leg than Conray. Iopamidol produced significantly less nausea and vomiting during the injection than Conray. There was no significant difference in the quality of the phlebograms with either of contrast medium.

Adolescent↗
PubMed1979

Effect of glucocorticoids and calcium intake on bone density and bone, liver and plasma minerals in guinea pigs.

The purpose of this study was to see what effect glucocorticoids would have on bone density and mineral distribution in guinea pigs. Adult female guinea pigs were given prednisolone, a synthetic analogue of cortisol, for up to 24 weeks. Bone density and bone, liver and plasma levels of zinc, copper, iron, manganese, chromium, magnesium and calcium were studied in these animals. In one study, the effect of menopause was simulated by using ovariectomy. In another study, dietary calcium was varied to investigate its effect with glucocorticoids. Animals treated with 1 mg prednisolone/kg body weight showed increased femur density compared with controls, but no changes in tissue mineral concentrations. Animals fed 100 mg prednisolone/kg body weight experienced decreased femur density. Differences in effects were not observed between ovariectomized and intact animals. Bone loss was greatest in animals fed the cereal-based closed-formula diet and least in animals fed the low-calcium diet. Changes in mineral content of femurs observed in animals which lost bone mass were increased iron concentration and decreased magnesium concentration. Total liver stores of zinc and magnesium increased. Liver copper increased in concentration per gram as well as in total content. Liver concentration of manganese decreased. Plasma changes in animals fed the high level of drug were decreased iron and calcium, and increased copper. Hemoglobin and hematocrit increased with increasing drug levels. It is suggested that glucocorticoids have marked effects on mineral metabolism which may be related to the bone loss and that these effects may be modified by dietary changes.

Animals↗
PubMed1977

Zinc requirement of the young guinea pig.

The zinc requirement and signs of zinc deficiency of the young guinea pig were investigated. One-week-old Hartley guinea pigs were fed low-zinc, semipurified diets with either 30% EDTA-treated casein or 30% EDTA-treated soybean protein as the protein source. Zinc was supplemented as ZnCO3 at 0, 3, 6, 9, 12, and 60 ppm (casein diets) and 0, 5, 10, 15, 20, and 60 ppm (soybean protein diets). Specificity of zinc deficiency was determined by rapid growth response to zinc supplementation following a 4-week period of zinc depletion. Significant growth retardation and decreased feed efficiency were seen in guinea pigs fed casein diets with 3 ppm zinc or less added, or soybean diets with 5 ppm zinc or less added. Plasma zinc concentration was significantly decreased in guinea pigs fed soybean diets supplemented with 20 ppm zinc or less. Less dramatic trends of decreased plasma zinc level were seen when low-zinc casein diets were fed. Plasma alkaline phosphatase activity showed significant decreases when 9 ppm zinc or less was added to casein diets and when 20 ppm zinc or less was added to soybean protein diets. Zinc (12 ppm) added to casein diets and 20 ppm zinc added to zinc soybean protein diets supported maximal growth rate for the 3-week duration of the feeding trials.

Age Factors↗
PubMed1976

Metabolic changes in golden hamsters fed vitamin B-12-deficient diets.

Various metabolic changes were observed in male hamsters fed vitamin B-12-deficient diets with or without supplements of cobalt, methionine, and a previously untested cobalt-free pseudovitamin B-12. The effects observed after 31 weeks of consuming the vitamin B-12-deficient diets included a marked increase in the urinary excretion of both methylmalonic acid and formiminoglutamic acid, slight increases in red blood cell mean corpuscular volume, and higher tissue levels of glutathione and activities of glutathione reductase and glucose-6-phosphate dehydrogenase. Vitamin B-12 in the diet prevented these changes, as did inorganic cobalt. The cobalt-free pseudovitamin B-12 showed no vitamin B-12 activity, neither did it have any potent antagonistic effect. Methionine supplementation reversed some of the metabolic changes. Addition of inorganic cobalt to the diet resulted in a significant increase in tissue stores of vitamin B-12.

Animals↗
PubMed1975

Milk and its role in the American diet.

A decline in milk consumption is postulated as a possible factor contributing to poor nutritional status. Certain common prejudices against milk may, rightly or wrongly, act as barriers to its consumption and, therefore, to its nutritional contributions. Beliefs such as "adults don't need milk;" "raw milk is better than pasteurized milk;" "nonwhite people shouldn't drink milk;" "saturated fat and cholesterol 'cause' heart disease;" "cows are ecologically unsound;" and "nutrition doesn't sell milk" can be counteracted in light of current scientific knowledge and information. It is reaffirmed that milk, in moderation, is a desirable inclusion in most people's diets.

Adolescent↗