PubMed Health⌕ Search

Biomedical subjects

G B Gerber

Publications and source records attributed to G B Gerber.

At least 55 records · Page 3Linked to original sources
PubMed1983

The effects of a fractionated gamma irradiation on life shortening and disease incidence in BALB/c mice.

BALB/c male mice (12 weeks old) were exposed to a single or fractionated exposure of 137Cs gamma rays. The fractionated dose was split into 10 equal doses delivered at an interval of 1 day. The causes and possible causes of spontaneous death were ascertained by autopsy and histological examination, and the data were treated by competing risk analysis. Life shortening followed a linear dose dependency and was about the same for fractionated (38.1 +/- 3.1 days/Gy) as for single (46.2 +/- 4.3 days/Gy) exposure. Death from tumor disease was enhanced and that from nonstochastic lung and kidney diseases was reduced after fractionated compared to single exposure.

Animals↗
PubMed1983

Life shortening and disease incidence in BALB/c mice following a single d(50)-Be neutron or gamma exposure.

Male BALB/c mice, 12 weeks old, were given a single exposure of either 137Cs gamma rays or d(50)-Be neutrons at a dose rate of 3 Gy/min. The animals were kept until death, and causes of death or possible causes of death were ascertained by autopsy and histology. The data were evaluated by competing risk methods. The survival time dose-effect curve for both types of exposure was linear and did not differ significantly (slopes: 55.8 +/- 4.0 days/Gy for neutrons and 46.2 +/- 4.3 days/Gy for gamma rays). The incidence of different diseases also was similar for both groups except that more carcinomas, sarcomas, and myeloid leukemias seemed to occur after neutron exposure and that nonstochastic lung and kidney diseases seemed to arise at lower doses.

Animals↗
PubMed1982

Transfer of antimony and arsenic to the developing organism.

The transfer of 73As and 125SB to the developing mouse organism was studied in the following ways. a)A diet containing the isotopes was given from the day of the vaginal plug and the radioactivity in uterus, ovaries and different maternal organs was determined 2,4, and 6 days after initiation of feeding. b)The isotopes were injected i.p. during organogenesis at day 12, and the transfer into the fetus as well as activity in maternal organs were followed for a period of 7 days. c)The radioactive diet was supplied during the entire pregnancy and 15 days thereafter. The radioactivity in the females was followed for 150 days, that in the litter for 50 days. Components of turnover of less than a day, less than a week and several months can be discerned in the adult for both isotopes and transfer to the fetus occurs during organogenesis. Less antimony than arsenic is transferred from food during fetal life. After birth, arsenic as well as antimony are taken up by the newborn via the milk.

Animals↗
PubMed1982

Interactions: dose effect relationships and isoeffect curves.

Interaction from several agents, i.e., a greater or smaller effects than expected from the sum of the individual effects can be of essentially two types: a) The agents could act in parallel on the same target, and a term depending on the doses of the agents involved would have to be added to the individual dose effect relationships (parergic interaction). b) The agents could act at different points in the chain of events leading to the observed effect, and the action of the second agent, the promotor, would be, at least in part, contingent on the action of the first inducer agent so that the dose effect relationships are linked in a multiplicative manner (metergic interaction). The dose effect surfaces for interaction depend on the type of dose effect relationship of the individual agents. Formulas are given for the general cases and are exemplified in graphs. Typical isobolic diagrams are also illustrated. These formulas may be adapted to experimental data by means of non-linear regression or maximum-likelihood analysis.

Computers↗
PubMed1981

The in vitro radiosensitivity of hemopoietic stem cells from control and preirradiated infant mice.

The radiosensitivity of hemopoietic stem cells isolated from infant mice (6 or 9 days of life), of infant preirradiated mice (exposed to 126 rad on day 6 and assayed at day 9 of life) and of adult C57/Bl mice was assayed on the basis of their capacity to form spleen colonies and to incorporate iododeoxyuridine after transplantation into heavily irradiated hosts. Stem cells of infant non-irradiated mice have a DO of 115 rad compared to 72 rad for adult mice whereas the DO of preirradiated infant mice has diminished to 80 rad. No significant difference was seen between spleen and bone marrow cells or between total cells and cells not sensitive to 3H-thymidine. It is postulated that this sensitization of stem cells caused by a preirradiation is responsible for the greater mortality of infant mice after fractionated exposure compared to a single one.

Aging↗
PubMed1981

Carcinogenicity, mutagenicity and teratogenicity of nickel.

Nickel is widely used in the metallurgical industry, and although not released extensively into the environment, may represent a hazard to human health. Owing to their low absorption from the gastrointestinal tract, nickel compounds, except nickel carbonyl, are essentially non-toxic after ingestion. Epidemiological investigations and experimental studies have demonstrated that certain nickel compounds are extremely potent carcinogens after inhalation, but also that the carcinogenic risk is limited to conditions of occupational exposure. The relatively small number of mutagenicity studies performed up to now do not yet allow definite conclusions as to whether nickel is mutagenic. Nickel can cross the placenta and has embryotoxic and teratogenic properties. The principal hazard of nickel to man, beside its carcinogenicity, however, is its ability to provoke reactions of sensitization.

Animals↗
PubMed1981

Development of glycolipids and gangliosides in lead treated neonatal rats.

Lead (0.01% or 0.1% in the diet) was given to rats from conception to an age of 14, 21 or 32 days, and the development of brain cerebrosides, sulfatides and gangliosides was followed. Animals which had received 0.1% lead displayed a marked retardation in the onset and a reduction in the final level (at 32 days) of the lipids characteristic for the myelination process (cerebrosides and sulfatides). A slight decrease was also seen in the level of gangliosides at 32 days. It is suggested that certain aspects of lead encephalopathy might be explained by the toxic effects of lead on the glia population and the consequent interference with normal formation of myelin.

Animals↗
PubMed1981

The effect of beta blockade on the reaction of pressure and mesenteric flow to biogenic amines in normal and X-irradiated rats.

A beta-blocker, propranolol, was infused to control and irradiated rats the 1st and 3rd day after 2-kR X-ray irradiation. Blood pressure and mesenteric blood flow were recorded during infusion of biogenic amines (noradrenaline, dopamine, serotonin, acetylcholine and histamine). After beta-blockade, there was intensified increase in pressure and decrease in flow with increased overshoot after infusion of noradrenaline, no effect on the increase in pressure and flow after dopamine, but an enhanced increase in pressure and decrease in flow after serotonin. No effect on the decrease in pressure and flow was seen after acetylcholine, and a greater decrease in pressure and flow, after histamine. Irradiation altered the vascular reactivity, mainly for noradrenaline, serotonin and histamine.

Acetylcholine↗
PubMed1980

Stem cell kinetics in spleen and bone marrow after single and fractionated irradiation of infant mice.

The number and type of stem cells in spleen and bone marrow of mice were determined after exposure to a single dose of 150 R on day 6, to a single dose of 500 R on day 6 or day 9 or to a fractionated dose of 150 R + 350 R on day 6 and 9. The stem cells were assayed on the basis of colony forming units (CFU) in spleen and of incorporation of iododeoxyuridine in spleen and bone marrow of lethally irradiated host mice. During the first months of life, the number of stem cells in non-irradiated mice increases markedly in bone marrow and slightly in spleen. Irradiation causes a long-lasting depression in stem cells, particularly in bone marrow and affecting preferentially erythropoietic precursor cells. Following a dose of only 150 R, the number of CFU in bone marrow is still below control levels 24 days later. An exposure to 500 R fractionated between day 6 and 9 has a markedly greater effect on stem cells in the spleen than the same dose given in a single application either at day 6 or 9.

Age Factors↗
PubMed1980

Iron incorporation after single and fractionated irradiation of infant mice.

The erythropoiesis in control and irradiated infant mice was investigated on the basis of incorporation of iron into hemopoietic organs and blood. Iron incorporation in bone marrow increased from the second week of life reflecting the maturation of the marrow whereas that in the spleen showed only minor changes. Irradiation of infant mice on day 6 or 9 caused a bone marrow syndrome characterized by an impaired iron incorporation into hemopoietic tissues and blood, by a reduced utilization of serum iron, and particularly by a delayed maturation of the erythropoietic functions of bone marrow. Fractionated irradiation not only had a greater effect on mortality but also caused a more severe and long lasting depression of erythropoiesis than a single dose.

Animals↗
PubMed1980

[Effect of phenoxybenzamine on mesenteric blood flow in irradiated rats].

Reactivity of the superior mesenteric artery has been studied in rat Wistar by infusion of biogenic amines (noradrénaline, dopamine, serotonin, acetylcholine and histamine) in presence of phenoxybenzamine. A decrease in reactivity of the post-synaptic alpha receptor located on the mesenteric vascular smooth muscle cell was seen three days after irradiation by 2 Kr.

Animals↗
PubMed1979

Chromosomal aberrations in bone-marrow cells of mice given a normal or a calcium-deficient diet supplemented with various heavy metals.

Mice kept on a normal (1.1% calcium) or low-calcium (0.03%) diet were exposed for one month to zinc chloride (0.5% Zn), lead acetate (0.5% Pb) or cadmium chloride (0.06% Cd) or to a mixture of these salts at half the above concentrations. These concentrations, given in a poor calcium diet, represent an LD 50/30 days. After the mice were killed bone-marrow cells were assayed for chromosomal aberrations, and serum calcium was determined. Chromosomal aberrations were detected in the mice maintained on a low-calcium diet and exposed to lead, zinc or a mixture of lead, zinc and cadmium. The possible mechanism for the synergistic action on genetic effects of the lack of calcium and intoxication by heavy metals are discussed, and it is recommended that routine attention be given to the state of calcium metabolism in heavy-metal intoxication.

Animals↗