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Biomedical subjects

G B Gerber

Publications and source records attributed to G B Gerber.

At least 73 records · Page 4Linked to original sources
PubMed1979

Late changes in biochemistry and blood flow in rat brain locally exposed to 30, 40, or 60 Gy.

Rat brain was exposed to 30, 40 or 60 Gy of roentgen rays and different biochemical and physiologic parameters were assayed from one day to 2 years. The most important changes noted were an intermediate increase in DNA, an intermediate to late--dependent on dose--increase in collagen, a decrease in sialic acid, an early to intermediate increase in serotonin, an increase in cathepsin, an early depression, and intermediate enhancement and a late decrease in alpha amino isobutyrate uptake by brain, and an early reduction, an intermediate--and sometimes late--increase in blood flow. These changes suggest that all three principal systems 2n the brain, nerve cells, glia and vascular system, participate in late changes.

Age Factors↗
PubMed1979

[Development of estradiol, progesterone, and prostaglandins E and F2 alpha levels during pregnancy in mice].

17 beta estradiol, progesterone, prostaglandin E and prostaglandin F2 alpha were determined in the plasma of mice at different times of pregnancy. Estradiol displays a preimplantation peak on day 4. Other peaks are visible at the end of the implantation period (day 6) and on day 10. Progesterone increases when implantation begins (day 5). Prostaglandins increase at the beginning of pregnancy and decrease temporarily before implantation. Other peaks are also apparent for prostaglandin E on days 5.5 and 11.

Animals↗
PubMed1979

Teratogenic effects of lead in the mouse.

Female mice of the C57B1 strain were mated and given from the first day of the pregnancy a normal diet, containing 1.1% of calcium, or a calcium-deficient one, containing 0.2% of calcium. Animals of the 2 groups were injected intra-peritoneally with 15 or 35 mg of lead acetate/kg at different times of the fetal organogenesis (8th, 9th, 10th or 12th day of the pregnancy). In the normal diet group, injection of lead increases the postimplantation mortality and the rate of skeletal anomalies among the fetuses. The anomalies are restricted to the anterior part of the axial skeleton and consist essentially in the fusion of 2 or more cervical vertebrae. In addition, lead diminishes the blood calcium levels in the pregnant females. In the calcium deficient group, all these effects of lead are considerably increased and fetuses suffer a loss of weight and delayed ossification. In the animals given such a diet but non lead-injected, the fetal weight is already diminished. However, the ossification and the rate of skeletal anomalies are not affected, and the blood calcium levels of the mothers are similar to those of the control females given a normal diet.

Abnormalities, Drug-Induced↗
PubMed1978

Repair and biochemical protection in life shortening of mice exposed to fractionated X-irradiation.

Male mice of the BALB/c+ strain were exposed to X-rays at fractionation intervals of 7, 15, 30, and 60 days. One group received a mixture of radioprotectors, another AET (only 30 days fractionation), a third one served as control. The doses ranged, dependent on the treatment, from 300--1500 R. When survival was corrected for acute death, the control and AET treated animals died after an accumulated dose of about 2000 R whereas those treated with a mixture of radioprotectors died after about 4000 tr. Bone marrow failure and lung damage is the main cause of death within the initial 200 days after start of the exposure. At later times, fibrotic changes and in particular glomerulosclerosis are observed.

Animals↗
PubMed1978

Increased ALA dehydratase activity and spleen weight in lead-intoxicated rats. A consequence of increased blood cell destruction.

Lead was given in the diet (1%) to rats from birth and at different times the animals were studies for delta amino levulinic acid dehydratase (ALAD) activity, spleen weight, 59Fe incorporation in erythrocytes and 51Cr-labeled erythrocytes survival. The increased ALAD and spleen weight found after lead treatment is explained as a consequence of a shortened survival, which results in a younger age of circulating erythrocytes with higher ALAD activity.

Animals↗
PubMed1978

Heme synthesis in the lead-intoxicated mouse embryo.

Incorporation of 55Fe and of [14C]glycine was studied in control embryos and mothers and in those which had received lead in the diet from day 7 of pregnancy. Incorporation of Fe into heme of embryonic liver which increases markedly for controls on day 17 of pregnancy was depressed greatly and showed no such increase in lead-intoxicated embryos. These embryos were retarded in growth but had normal heme concentrations in body and liver. Incorporation of glycine into embryonic heme and proteins was not affected. Data on incorporation in the mothers are also presented. It is thought that the impaired synthesis of heme in lead-intoxicated embryos limits their body growth during the late phase of pregnancy.

Animals↗
PubMed1978

[Blood pressure and mesenteric blood flow in rats during the infusion of biogenic amines. Effect of supralethal irradiation].

The action of biogenic amines (noradrenaline, dopamine), infused at different concentration into the aorta of the urethane anesthetized control and irradiated rats for 2 min., was followed on the basis of systemic blood pressure and mesenteric blood flow. The mesenteric blood flow was measured by means of an electromagnetic flow meter. The changes observed i.e. after dopamine an increase in pressure and flow, after noradrenaline an increase in pressure and a decrease in flow with an increase after infusion had been stopped, correspond to those obtained in larger animals. In many, but not in all cases, the response is proportional to the log of the concentration of the amine infused. Irradiation with 2 kR, i.e. a dose which causes the animals to die from the gastrointestinal syndrome after 3 days, modified the response to dopamine and noradrenaline. The changes are, for noradrenaline, a greater pressure and a lower flow responses and for dopamine a greater pressure response at low and middle doses.

Animals↗
PubMed1977

Plasma hormone levels in normal and lead-treated pregnant mice.

Dietary lead (0.5%) was given to mice which, after mating, exhibited a vaginal plug. Estradiol, progesterone and prostaglandins E and F 2 alpha were determined in the plasma by radioimmuno assay at different times thereafter. The increase in estradiol and decrease in prostaglandins prior implantation are not greatly altered by lead treatment, whereas the subsequent increase in progesterone and later in estradiol is abolished. It is concluded that the lower number of pregnancies seen in lead-treated mothers is due to a maternal hormonal imbalance caused by lead.

Animals↗
PubMed1977

Absorption of different amino acids by an intestinal preparation from normal rats and from rats exposed to supralethal X-irradiation.

Absorption of different amino acids [lysine, alpha-amino isobutyrate (AIB), methionine, alanine, glycine] was studied in an intestinal in vivo preparation from normal and X-irradiated rats (1 and 3 days after 2000 R). Absorption of amino acids under loading and in presence of other amino acids was also followed. Lysine and AIB absorption follow a saturation kinetics with a maximal velocity of 35 and 85.6 micronmoles/min and a Kt of 10 and 67 micronmoles for lysine and AIB respectively. Interference in absorption exists not only between amino acids of the same class, but also by lysine on neutral amino acids. One day after irradiation, absorption is normal or even enhanced, although active transport appears impaired as indicated by the increase in Kt. Three days after exposure absorption, particularly the active one, is severely depressed. This is indicated by the low Vm and high Kt as well as by the fact that loading has little influence on absorption.

Alanine↗
PubMed1977

The radiosensitivity of chromosomes of rabbit lymphocytes.

Dicentrics were induced in human and rabbit lymphocytes in vitro by exposure to X-irradiation. The yields were compared with data reported in the literature. To elucidate the reasons for the different findings we have evaluated the parameters for the different models by maximum likelihood methods. From this analysis it can be concluded that the earlier claim of Bajerska and Liniecki [1] that both species have the same radiosensitivity must be discounted, and that their similarity was due to the abnormally low values these investigators observed in irradiated human lymphocytes.

Animals↗
PubMed1977

Chromosomal abnormalities in lymphocytes from monkeys poisoned with lead.

Cynomolgus monkeys (Macaca irus) were given 0, 1.5, 6 or 15 mg of lead acetate 6 days a week for 16 months. Another group, also receiving 6 mg, was kept on a low-calcium diet. Each experimental group consisted of 2 monkeys. Chromosome analysis on cultured lymphocytes was carried out after 3, 10 and 16 months of lead treatment. The frequency of severe abnormalities (dicentrics, rings, translocations and exchanges) was significantly increased only in the group on a low calcium diet, whereas "light" abnormalities (gaps and fragments) increased with time in all groups receiving lead irrespective of the diet. The blood lead data indicate the severity of the lead poisoning.

Animals↗
PubMed1977

Cytogenetic investigations on mice treated with lead.

Dietary lead at different dose levels was given to female C57B1 mice for periods up to 3 months. No severe chromosome or chromatid aberrations were observed at any dose level and the frequency of chromatid gaps increased significantly only at the highest doses. (0.5 and 1% of lead in the diet). The number of micronuclei in polychromatic erythrocytes also remained at control levels after lead treatment, whereas known mutagenic agent such as Myleran and Mitomycine C raised their incidence markedly. Taking into account also the data in the literature, it is concluded that lead per se probably has no mutagenic action on mammals.

Animals↗
PubMed1977

Chromosomal aberrations in workers professionally exposed to lead.

Chromosomes in cultured lymphocytes from the following groups were analyzed: 16 workers from a smelting plant for storage batteriers in Lyon, France; 7 workers from a factory where tin dishes are made at Nerem, Belgium; and 20 controls. The choice of the workers was made on the basis of either elevated blood lead (Lyon) or elevated urinary delta-aminolevulinic acid (Nerem). An increased number of severe aberrations--rings and dicentrics--were detected in the persons from Lyon, whereas no such aberrations but an increased number of fragments were seen in those from Nerem.

Belgium↗
PubMed1977

In vivo absorption of carbohydrates in rats with gastro-intestinal radiation syndrome.

Absorption of glucose and sucrose by intestine from supralethally irradiated rats was investigated using an in vivo preparation. An activation of glucose absorption one day day after exposure is followed by a marked fall in glucose and sucrose absorption on day 3. Experiments under different conditions of loading indicate that at 20 hours active transport of glucose is already impaired although the maximum velocity is increased. After 3 days maximum velocity and active transport decrease markedly. Inverstase activity increases after 20 hours, but this is not accompanied by an increased sucrose absorption. The defect in sucrose absorption 72 hours after irradiation is paralleled by a decrease in invertase activity.

Animals↗
PubMed1977

Biochemistry of late effects in rat lung after hemithoracic irradiation.

The right hemithorax of rats was exposed to 1 kR of roentgen rays, the animals were killed at different times, and various physiologic and biochemic parameters (DNA, protein, collagen, sialic acid, lysosomal enzymes, fibrinolytic activity, peroxides and blood flow ratio between irradiated and non irradiated lung) were determined from 1 day until 11 months after irradiation. A decrease in relative blood flow was observed from 2 weeks until 11 months, a decrease in phospholipids from one to 3 months and a decrease in fibrinolytic activity from 1 day to 11 months after irradiation. At several times a decrease in sialic acid and cathepsin D was also noted. The changes are discussed with respect to the pathogenetic mechanisms of late lung damage.

Acid Phosphatase↗