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Biomedical subjects

G A Robinson

Publications and source records attributed to G A Robinson.

At least 73 records · Page 4Linked to original sources
PubMed1976

Ovarian 125I transference in the laying Japanese quail: apparent stimulation by FSH and lack of stimulation by TSH.

Six-hour accumulations of 125I were measured in the growing oocytes and thyroids of laying Japanese quail injected with 0.002 to 2 mg. of FSH or 0.004 to 4 I.U. of TSH per day for six days. FSH at 0.2 and 2 mg./day increased the 125I content of the growing oocytes to 1.4 times the control values. The numbers and the total weights of these growing oocytes doubled. The egg-laying rate remained unchanged. The FSH-induced apparent stimulation of 125 I transference was seen as a consequence of the increase in oocyte material rather than to a direct effect of FSH on the membranes of the avarian follicular cells. TSH did not increase the transference of 125I.

Animals↗
PubMed1975

Rate of thyroxine secretion by male and laying Japanese quail: identification of the radioactive thyroxine degradation component of the multiphasic 131-I curve.

Counting of radioactivity in Japanese quail in vivo showed a rapid loss of 131-I from the body 12-24 h after the i.v. injection of [131-I]thyroxine (T4), followed by a period of slow decrease in counting rates to 96 h. From comparison of these [131-I]T4 curves with curves for 131-iodide-injected birds and from counts on serum and other tissues in vitro it was concluded that, for Japanese quail, the T4 secretion rate should be calculated using serum samples taken during the first 12 h. Using this time period, the parameters measured were: T4 distribution space, laying hens 45-7 and mature cocks 26-7 and mature cocks 26-3 ml/100 g body weight; fractional degradation rate for T4, hens 5-73 and cocks 3-12/day; serum T4 concentration (Tetrasorb-125 method), hens 1-20 plus or minus 0-07 and cocks 1-34 plus or minus 0-05 (S.E.M.) mug/100 ml (n= 16); T4 secretion rate, hens 3-14 and cocks 1-10 mug/100 g/day.

Animals↗
PubMed1975

The kinetics of hematopoiesis in the light horse II. The hematological response to hemorrhagic anemia.

Hemorrhagic anemia was experimentally produced in three Standardbred horses by removing approximately 63% of the red cell mass and the accompanying plasma during a three day interval. Red cell parameters were examined daily for 45 days and then weekly until termination of the experiment 250 days after production of the anemia. Leukocytes, platelets and bone marrow aspirates were examined at regular intervals for 25 days after the final phlebotomy. At 24 hours after the last bleeding, 75-selenomethionine was injected intravenously to measure the lifespan of the newly produced erythrocytes. The erythrocyte lifespan was found to be 139 days as compared to the 155 day erythrocyte lifespan for three normal standardbred horses measured previously by similar techniques. The maximum decrease in erythrocyte numbers occurred four, two and two days following the last phlebotomy to 43, 39 and 44% of the original values. The prebleeding erythrocyte levels were regained at approximately 63, 91 and 98 days respectively. During the initial 45 days post phlebotomy the maximum increase in mean cell colume was 2, 4 and 7 mj-3 respectively. During the recovery period there was erythrocyte production of 6.84, 6.99, and 6.12 x 10-9 cells/kg/day. At the same time the absolute production of hemoglobin was 44.6, 50.0, and 51.0/gm/day or on a relative basis 0.096, 0.114 and 0.113 gm/kg/day.

Anemia↗
PubMed1975

The kinetics of hematopoiesis in the light horse III. The hematological response to hemolytic anemia.

The hematological response to acetylphenylhydrazine hemolytic anemia was studied in three standardbred horses. The lifespan of erythrocytes produced during the most severe phase of the anemia were measured with 75-selenomethionine and found to be 144 days as compared to the 139 day lifespan in response to hemorrhagic anemia or 155 days in normal standardbred horses measured previously using the same technique. The erythrocyte counts returned to initial values in 42 days (37, 34 and 54 days) a mean erythrocyte production of 6.4 times 10-12 erythrocytes/day. The mean hemoglobin production was 0.31 gm/kg body weight/day as compared to 0.11 gm Hb/kg/day previously observed in response to hemorrhagic anemia. The mean increase in erythrocyte mean cell volume was 12 mu-3 during the acute response phase to hemolytic anemia in contrast to the absence of a significant increase in the mean cell volume as previously observed during response to hemorrhagic anemia. Free Heinz bodies separated from erythrocytes during the acute phase could not be differentiated from platelets on the hemocytometer counting chamber with standard techniques.

Anemia, Hemolytic↗
PubMed1974

The kinetics of hematopoiesis in the light horse. I. The lifespan of peripheral blood cells in the normal horse.

Three Standardbred horses were given 0.2 mg (1 mCi) of (75)selenomethionine intravenously and a second group of three were given 10 mCi of tritiated diisopropylfluorophosphate (0.5 mg) intravenously. Observations on labeled cells were continued for 250 days after radioselenium injection and 160 days after tritium injection. The lifespan of erythrocytes using (75)selenmethionine was 155 +/- 10 days and 148 +/- 7.8 days using tritiated diisopropylfluorophosphate. There was no significant difference at the 10% level between the lifespans, using these labels. The uptake of radioselenium into erythrocytes reached a mean maximum of 11.5% at 82 +/- 18.9 days after injection of the label. There was an elution of from 17.6% of the injected dose of tritium label down to 7.5% eight days after injection of this isotope. From this study both of these labels appear to be satisfactory for determining the erythrocyte lifespan of the horse. The mean time of the curve of mean radioselenium activity of peripheral blood leukocytes for the three horses was 5.54 days and the lifespan of these cells was seven days. The mean lifespan of peripheral blood leukocytes of the three horses after in vivo labelling with tritiated diisopropylfluorophosphate was 17.3 hours. No specific labelling was found in bone marrow or peripheral blood cells at this level of tritium labelling by dipping emulsion autoradiography. The mean lifespan of equine platelets for three horses using radioselenomethionine was 9.2 days and the mean lifespan of equine platelets using tritiated diisopropylfluorophosphate was 6.6 days in a group of three horses.

Animals↗
PubMed1974

Studies with radioactive endotoxin. I. Clearance of 51Cr-labelled endotoxin from the blood of calves.

The clearance of (51)Cr-labelled Pseudomonas endotoxin from the blood was studied in calves in a nontolerant and in an endotoxin-tolerant state. Calves were rendered tolerant to the toxic effects of the endotoxin by four daily intravenous injections of endotoxin at the dose rate of 5 microg/kg body weight. Clearance of a small amount of (51)Cr-endotoxin from the blood of nontolerant calves was almost complete within three minutes of injection and was not significantly faster in tolerant calves. The lungs and liver were the major organs involved in clearance of endotoxin from the blood. The (51)Cr label was slowly excreted by the kidneys. Neither platelets nor leukocytes were demonstrated to participate in endotoxin clearance in calves. (51)CrCl(3) was injected into control calves. Relative to the distribution and loss of labelled endotoxin, the (51)CrCl(3) was cleared slowly from the blood, was distributed uniformly throughout the body and was excreted rapidly.

Animals↗