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Biomedical subjects

M Berlin

Publications and source records attributed to M Berlin.

At least 19 recordsLinked to original sources
PubMed1992

Mercury distribution in the rat brain after mercury vapor exposure.

Brown Norwegian rats were exposed to mercury vapor at a concentration of approximately 1 mg/m3 for 5 weeks 24 hr/day 7 days a week and 6 hr/day 3 days a week, respectively. The total mercury absorption was calculated to 264 and 35 micrograms per week and 100 g body weight. The mean blood mercury concentration was 0.25 +/- 0.03 and 0.09 +/- 0.01 microgram/g, and the total concentration in the brain was 5.03 +/- 0.73 and 0.71 +/- 0.10 microgram/g tissue, respectively. The mercury distribution in the brains was examined using a method based on chemographic principles. Mercury was found primarily in the neocortex, in the basal nuclei, and in the cerebellar Purkinje cells. This distribution pattern corresponded to the pattern of inorganic mercury described after exposure to methyl mercury. Distribution of mercury after administration of different mercury compounds is discussed.

Administration, Inhalation↗
PubMed1992

Birth weight of children and cadmium accumulation in placentas of female nickel-cadmium (long-life) battery workers.

In a retrospective epidemiological study on the birth weight of 266 children of 137 female workers in a nickel-cadmium battery factory, 157 children of workers occupationally exposed to cadmium were compared with 109 born to non-occupationally exposed workers. No effect of cadmium exposure on birth weight was detected, but a statistically significant effect on birth weight of smoking during pregnancy was observed. In a prospective study on the same population of female battery workers, 27 placentas were collected and the cadmium distribution and concentration in tissue subsamples determined. Placental cadmium concentrations were positively correlated with maternal blood cadmium. The cadmium concentration in placentas ranged from < 0.002 to 0.095 microgram/g (wet weight), the mean concentration +/- SD was 0.021 +/- 0.022 microgram/g (wet weight). Morphological and ultrastructural studies of placental tissues did not reveal any effect of cadmium. This study did not provide any evidence in support of the hypothesis that the placenta may be the critical organ in exposure to cadmium.

Adolescent↗
PubMed1989

Excimer laser ablation of the human lens at 308 nm with a fiber delivery system.

A 308 nm excimer laser has been used with a fiber delivery system to perform ablation of the human lens. Preliminary results demonstrate the system's ability to ablate lens nucleus and cortex selectively, preserving the anterior and posterior capsules. The total delivered energy necessary to ablate a human lens ranged from 35 to 63 joules. Laser tissue interaction and ablation rates were computed for the different components of the human lens (capsule, cortex, nucleus) for the operatively useful energy densities (fluences). Operative experience suggests that cortex and nucleus can be ablated while preserving the capsule if an adequate irrigation and aspiration system is developed. These results also suggest that this modality may be adequate for performing endocapsular cataract extraction. Laser tissue interactions were also computed at variable distances between the fiber tip and tissue. As this distance increased, the spread of the beam increased and a significant increase in energy was necessary to induce tissue ablation. This was due to the decrease in fluence with increasing distance to the target tissue and/or the absorption and scattering of the delivered energy within a short distance from the fiber tip by the ablated material. Evidence of a sonic effect was also present.

Aged↗
PubMed1979

Biological threshold limits for benzene based on pharmacokinetics of inhaled benzene in man.

Volunteers were exposed to benzene, 2--10 ppm, under controlled conditions up to 6 h a day during five consecutive days. The accumulation and elimination of benzene was measured by determination of benzene concentration -- down to 0.001 ppm -- in exhaled breath. From these observations, a multicompartment model, which approximately describes the kinetics of benzene elimination and accumulation has been designed. On the basis of this model, benzene concentrations in breath, corresponding to exposure levels of benzene, have been estimated. Thus, at a daily exposure to 10 ppm the exhaled benzene concentration in the morning after a day of exposure will not exceed 0.1 ppm.

Aerosols↗
PubMed1978

Interaction between selenium and inorganic mercury.

Data on mercury and selenium interaction in the mammalian body are reviewed. Experimental data from studies on rats show that selenium interacts with mercury metabolism and toxicity after exposure to mercuric mercury. Autopsy data from workers exposed to mercury vapor indicate an association between mercury and selenium retention in the central nervous system, suggesting the formation of a mercury-selenium complex. In animal experiments, mercuric mercury interferes with selenium metabolism and toxicity. Available data do not, at present, permit deduction as to whether additional selenium intake in man, exposed to mercury vapor or mercuric mercury, will have any effect, beneficial or adverse.

Animals↗
PubMed1976

Aging and the central nervous system.

This review of the literature on aging and the central nervous system attempts to cover the basic perameters investigated at both human and infrahuman levels for the better part of the last century. The results have indicated that there is a rather considerable lack of consistency in the data both within the frame of reference of a single species, and with regard to intraspecies comparisons. We have suggested that possible reasons for the contradictory findings would rest upon variability in techniques employed but, perhaps more importantly, on the failure of investigators in this area to standardize terminology. It is suggested that such a standardization might well be one of the more useful things to be accomplished in order to facilitate the interpretation of future work. The literature review first dealt with gross, i.e., macroscopic changes in brain morphology that could correlate with age, and then covered changes at the microscopic level. Finally, a brief review of the literature with regard to the biochemistry of aging was carried out. Implications of the data were noted where appropriate.

Aging↗
PubMed1975

Distribution and metabolism of 2,4,5,2', 5'-pentachlorobiphenyl.

Single doses of 2,4,5,2',5-pentachlorobiphenyl uniformly labeled with 14-C have been administered intravenously and orally to mice. Whole-body autoradiograms and scintillation counting of tissue samples have shown that most radioactivity leaves the circulation for the tissues within one hour. Peak concentrations varied, being highest in brown fat, which after 24 hours comprised the major reservoir of the unchanged compound in the body. Radioactivity disappeared rather rapidly drom most other tissues, although the longest retention occurred in bronchial epithelium and some parts of the renal tubules. The excretion of radioactivity was mainly through the bile, into feces, with a half-time of six days. There was little unchanged compound in the feces, the major metabolite was a hydroxylated derivative, both free and conjugated.

Adipose Tissue, Brown↗
PubMed1975

Dose-dependence of methylmercury metabolism. A study of distribution: biotransformation and excretion in the squirrel monkey.

The distribution and excretion of different body burdens of methylmercury (MeHg) have been investigated in the squirrel monkey. In monkeys given weekly 0.8 mg/kg doses, orally, of 203-MeHg, a linear correlation was observed between the concentrations of radioactive Hg in the blood and brain to as much as a blood concentration of 1 mug/gm. Above this level, the ratio of concentration in the brain and blood was increased. The total Hg concentration in bile collected from the bile duct was 10% to 30% of that in blood, while the concentration in bile from the gallbladder approached that in the blood. The total Hg concentration in feces was always more than ten times that in urine. Biotransformation of MeHg to inorganic mercury has been demonstrated; in the liver about 20% of the total mercury was inorganic, in the kidney 50%, and in the bile 30% to 85%. In the brain less than 5% of the total mercury was inorganic. After a single 0.8 mg/kg dose, orally, of 203-MeHg, the halftime for total Hg in blood was 49 plus or minus 2.8 days, and in the whole body 134 plus or minus 2.7 days. During the first four days after dosing, the decrease in blood concentration was more rapid than that occurring later, due to a redistribution within tissue compartments. A differential distribution of MeHg within the brain has been demonstrated in animals that showed clinical signs of intoxication.

Animals↗
PubMed1975

Neurotoxicity of methylmercury in squirrel monkeys. Cerebral cortical pathology, interference with scotopic vision, and changes in operant behavior.

Blood mercury was raised to levels exceeding 1,000 ng/gm by weekly oral doses of methylmercury hydroxide to squirrel monkeys. Operant behavior tests were employed and neurological signs were recorded on film. Sudden visual disturbance occured with subacute exposure. Prolonged exposure resulted in impaired coordination with impairment of scotopic vision and possibly also sensory disturbances. Scotopic vision was tested by determining the critical fusion intensity (cfi) at 10 cps. An increase in cfi was the earliest neurological sign appearing in some monkeys months before other signs could be detected. Poisoned monkeys exhibited typical cerebral cortical lesions. The visual cortex was invariably involved. Extension to adjacent cortical areas increased with increasing duration of exposure and increasing brain mercury. The microgram per gram brain tissue was the lowest concentration of methylmercury seen wiht morphological lesions.

Animals↗