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Biomedical subjects

R Green

Publications and source records attributed to R Green.

At least 505 records · Page 28Linked to original sources
PubMed1975

Comparison of results of microbiologic and radioisotopic assays for serum vitamin B12 during pregnancy.

The serum vitamin B12 level falls progressively during pregnancy, when measured either by microbiologic assay or by a radioisotope dilution technique. The concentration of the vitamin assayed by radioisotope dilution was consistently higher than the value obtained by microbiologic assay. This discrepancy was greatest in early pregnancy and decreased as the duration of pregnancy increased. These results add further evidence to the hypothesis that changes in serum binders for vitamin B12 are of major significance in the pathogenesis of the observed fall in serum levels of the vitamin during pregnancy.

Biological Assay↗
PubMed1975

Regional myocardial infarction at operation. An automated system of identification.

The difference between normal and infarcted myocardium at operation cannot always be defected by inspection or palpation. Infarcted myocardium may be identified by a decrease in the amplitude of the ventricular bipolar electrogram. Although this method is reliable and reproducible, it requires a second observer's visual analysis and interpretation of the electrogram signal. This method is therefore subject to the vagaries of human observation, analysis, and accounts of rapidly changing data. We have designed and built an automated instrument to simplify the recognition of transmural infarction.

Animals↗
PubMed1975

Vitamin B12 metabolism in the fruit bat (Rousettus aegyptiacus). The induction of vitamin B12 deficiency and its effect on folate levels.

1. Vitamin B12 metabolism was studied in bats of the species Rousettus aegyptiacus, which live on an all-fruit diet in the wild. 2. There was a wide range in values for the serum vitamin B12 concentration of newly captured bats, but bats captured in the early spring had significantly higher mean serum vitamin B12 levels than bats captured in the early autumn. 3. There was an exponential decrease in serum vitamin B12 concentration with time in captivity for bats fed on a vitamin B12-deficient, all-fruit diet; the biological half-life was 80 d in serum, 109 d in liver and 164 d in kidney. 4. The main storage organ for vitamin B12 in the bats was the liver, mean content 1067 ng vitamin B12. After 50 d, injected [57Co]cyanocobalamin had equilibrated with body vitamin B12 stores, and 17% of the retained radioactivity was present in the liver. From these results it was calculated that the total body vitamin B12 content of the bat was c. 6500 ng. 5. The biological half-life of injected [57Co]cyanocobalamin was 70--88 d and the calculated daily requirement was 50--60 ng (0-2 mug/kg body-weight per d). 6. As serum vitamin B12 levels decreased, serum folate levels increased. The erythrocyte folate concentration increased significantly after 130 d on the all-fruit diet and then decreased to the initial values after 190 d. 7. Vitamin B12 metabolism in the fruit bat is similar in many respects to that of man, but on a 'weight-for-weight' basis the bat has a 5- to 15-fold greater requirement for this vitamin. 8. Vitamin B12 deficiency may be induced fairly rapidly in fruit bats fed on an all-fruit diet.

Animals↗
PubMed1975

Prevention of folate deficiency by food fortification. II. Absorption of folic acid from fortified staple foods.

The absorption of folic acid from maize, rice and bread fortified with pteroylglutamic acid was compared with that of an aqueous solution of pteroylglutamic acid in the same subjects. Feeding fortified maize and rice produced similar increments in folic acid concentration, which were approximately half those observed with the pteroylglutamic acid solution. Fortified bread produced a lower increment. Pteroylglutamic acid was found to resist destruction by boiling and baking at temperatures and times used for the conventional preparation of such foods. However, baking for longer periods resulted in a loss of folic acid activity. It is concluded that fortification of staple foods with folic acid may offer a practical adjunct to nutritional programs designed to improve the intake of essential nutrients.

Absorption↗
PubMed1975

Prevention of folate deficiency by food fortification. III. Effect in pregnant subjects of varying amounts of added folic acid.

Maise meal fortified with folic acid was administered to subjects in late pregnancy in a daily dose of either 500 or 300 mug of folic acid. Changes in hematological and folate nutritonal status were compared to those in subjects receiving 300 mug folic acid/day in tablet form, and also in subjects in a previous study who received unfortified maize meal (control group) or meal containing 1,000 mug folic acid/day. In all groups receiving folic acid, red cell and serum folate levels rose progressively, and the rate of rise increased with increasing doses of folic acid. Maize meal containing a daily dose of 500 mug folic acid produced an effect similar to that of 300 mug daily in tablet form. Maize containing 300 mug added folic acid daily was effective in preventing the progression of folate depletion in late pregnancy.

Dose-Response Relationship, Drug↗
PubMed1975

Prevention of folate deficiency by food fortification. IV. Identification of target groups in addition to pregnant women in an adult rural population.

In a rural Negro population subsisting on a predominantly maize meal diet, the incidence of folate deficiency was 43.8% in nonanaemic women in late pregnancy, 32.1% in nonpregnant women, and 18.6% in adult males. More than one-third of all subjects older than 60 were deficient. No instance of unequivocal vitamin B12 deficiency was revealed in 431 subjects sampled, and it is considered that the hazards of giving a small daily dose of folic acid in this population are negligible. These findings warrant food fortification with folic acid in this and similar population groups.

Adolescent↗
PubMed1975

Prevention of folate deficiency by food fortification. VII. The use of bread as a vehicle for folate supplementation.

Bread fortified to contain a daily dose of 900 mug folic acid was administered to patients in late pregnancy. The patients receiving the bread showed significant rise in red cell folate concentration. The rise was similar to that observed in women receiving a daily dose of 300 mug of folic acid in tablet form. It is concluded that bread may be used as a vehicle for folic acid fortification.

Africa, Southern↗
PubMed1975

Ionic requirements of proximal tubular sodium transport. I. Bicarbonate and chloride.

Simultaneous perfusion of peritubular capillaries and proximal convoluted tubules was used to study the effect of varying transepithelial ionic gradients on ionic fluxes. Results show that net sodium influx and volume flux was one-third of normal when bicarbonate was absent, no chloride gradient existed, and glucose and amino acids were absent. Addition of bicarbonate to the luminal fluid did not restore the flux to normal, but peritubular bicarbonate did restore it. A chloride gradient imposed when no bicarbonate was present could only increase the fluxes slightly, but his flux was significant even after cyanide had poisoned transport. Reversing the chloride concentration gradient decreased the net sodium and volume fluxes whether bicarbonate was present or not. Glucose had no effect on fluxes, but substitution of Na by choline abolished them entirely. It is concluded that sodium is actively transported, that a chloride concentration gradient from lumen to plasma could account for up to 20% of net transport, and that peritubular bicarbonate is necessary for normal rates of sodium and fluid absorption.

Animals↗
PubMed1975

Ionic requirements of proximal tubular sodium transport. II. Hydrogen ion.

Simultaneous perfusion to proximal convoluted tubules and peritubular capillaries was used to study the effects of different perfusion fluids on sodium reabsorption and hydrogen secretion, which was calculated as bicarbonate reabsorption and titratable acid. Results show that sodium reabsorption was not tightly coupled to hydrogen secretion. Bicarbonate stimulates both sodium reabsorption and hydrogen secretion, but Tris stimulates only sodium reabsorption. Imposing an adverse chloride gradient across the proximal tubule (C1- peritubular greater than C1- luminal) decreased sodium reabsorption but did not diminish hydrogen secretion. Diamox inhibited both net sodium and hydrogen transport. It is concluded that there is not firm linkage between sodium reabsorption and hydrogen secretion and that bicarbonate probably stimulates sodium transport by a number of mechanisms, including an effect on the sodium transport unrelated to its ability to increase hydrogen ion secretion.

Animals↗
PubMed1975

Results of direct coronary artery surgery in women.

In the past 4 years, among 260 patients receiving coronary bypass grafts for coronary artery disease and stable angina pectoris, there were 34 women (13 per cent). The operative mortality rate for women was 8 per cent (3 of 34), and one late death due to myocardial infarction occurred in spite of a patent coronary bypass graft. The intraoperative infarction rate was 20 per cent (6 per cent in men). Although preoperative cardiac pump and muscle function parameters were better in women than in men (p less than 0.05), postoperatively only 30 per cent of women showed improvement in function as compared with 50 per cent of men. At 6 to 46 months' follow-up, 84 per cent of women were free of angina in contrast with 94 per cent of men. The early (4 month) graft patency rate was 50 per cent (14 of 27 grafts), as opposed to 80 per cent (20 of 25 grafts) in men. These results indicate that, although coronary artery disease shows anatomic similarity in women and men, the result of coronary revascularization in women is inferior to that in the male population.

Adult↗
PubMed1975

Scalp avulsion.

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Adult↗
PubMed1975

A wandering bullet. Successful removal and a simple technique to prevent its migration.

Bullet migration toward and within the pulmonary circulation occurred in a case of gunshot wound to the right upper abdominal quadrant. Difficulties in locating the missile were encountered during surgical attempts to remove it. Finally, a Swan-Ganz catheter was used for pulmonary angiography. The balloon of the catheter was inflated to prevent further migration of the missile until it could be surgically removed.

Abdominal Injuries↗
PubMed1975

Vitamin B12 and its binding proteins in the serum of some wild game species.

The concentration of vitamin B12 and its binding proteins was measured in the impala, nyala, wildebeest, zebra, bushpig, warthog, and rhino, all existing in their natural state. Marked differences were found between some species. The variations observed are probably true species differences, unrelated to environmental factors.

Animals↗
PubMed1975

Normal vitamin B12 turnover in subacute combined degeneration of the spinal cord.

Vitamin B12 turnover studies were carried out in 2 patients with pernicious anemia and subacute combined degeneration of the spinal cord. The retention of a tracer dose (0.5 mug) of intravenously administered 58Co-labeled vitamin B12 in these 2 patients was measured by whole-body monitoring over periods of 94 and 134 days. Vitamin B12 turnover (per cent per day) was calculated and the results compared with normal subjects and with pernicious anemia patients having no neurologic dysfunction. The loss of radioactive-B12 from the body was described by a single exponential model, confirming that the loss of vitamin B12 takes place as though from a single pool. There was no difference in vitamin B12 turnover between the patients with subacute combined degeneration of the spinal cord and normal subjects or other pernicious anemia patients without neurologic involvement. These findings contradict the suggestion that the development of neuropathy in vitamin B12 deficiency might be related to an increased requirement for vitamin B12.

Adult↗