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Biomedical subjects

M R Krigman

Publications and source records attributed to M R Krigman.

At least 55 records · Page 3Linked to original sources
PubMed1975

Acute lead encephalopathy in the guinea pig.

Acute lead encephalopathy was induced in adult guinea pigs with daily oral doses of lead carbonate. Cerebral capillaries were examined by electron microscopy, and the blood-brain barrier (B-BB) evaluated with Evans blue and horseradish peroxidase. Brain lead levels were also determined during the developing encephalopathy. There was no cerebral capillary alteration or demonstrable B-BB dysfunction. Brain lead concentrations increased over the 5-day period. The encephalopathy in the absence of any vascular alteration suggests that lead can produce a primary toxic effect at the neuronal level.

Animals↗
PubMed1975

Blood-brain barrier dysfunction in acute lead encephalopathy: a reappraisal.

Acute lead encephalopathy was induced in adult guinea pigs by administering daily oral doses of lead carbonate. During the development of the encephalopathy, the structural and functional integrity of the blood-brain barrier was evaluated with electron microscopy and tracer probes. Blood, cerebral gray matter, liver, and kidney were analyzed for lead, calcium, and magnesium content. The animals regularly developed an encephalopathy after four doses of lead. There were no discernible pathomorphologic alterations in the cerebral capillaries or perivascular glial sheaths. Furthermore, no evidence of blood-brain barrier dysfunction was demonstrated with Evans blue-albumin complex or horseradish peroxidase. Blood-brain barrier permeability to radiolead was not increased in the intoxicated animals. During the development of the encephalopathy there was a progressive rise in the lead concentration in all tissues. Concurrently, there was a significant rise in brain calcium. These results suggest that the encephalopathic effects of lead may be mediated directly at the neuronal level.

Animals↗
PubMed1975

The effects of chronic oral methyl mercury exposure on the lysosome system of rat kidney. Morphometric and biochemical studies.

This report describes morphometric and biochemical changes in the renal lysosome system of rats exposed to 3, 5, or 10 p.p.m. concentrations of methyl mercury hydroxide in their drinking water for 4 weeks. Increased numbers of dense, granular lysosomes, previously found to contain mercury, were observed in tubule cells of rats receiving the 3 and 5 p.p.m. dose levels but not those of the 10 p.p.m. group. Tubule cells from animals given the 10 p.p;m. dose level displayed proteinaceous vacuoles with dense crystalloid structures, apical cytoplasmic extrusion, and cellular degeneration; Mitochondrial swelling within tubule cells of treated animals showed a marked dose-response relationship. Renal microsomal activity levels of ss-glucuronidase were strongly inhibited by methyl mercury hydroxide exposure at all dose levels, whereas the activity levels of acid phosphatase were unchanged. Lysosomal beta-glucuronidase was also inhibited by methyl mercury hydroxide exposure, whereas lysosomal acid phosphatase showed approximately a 2-fold increase in activity. The results are discussed in relation to the role of lysosomes in mediating the nephrotoxic effects of methyl mercury and other toxic trace metals.

Acid Phosphatase↗
PubMed1974

Effect of lead intoxication on the postnatal growth of the rat nervous system.

Lead encephalopathy was induced in developing Long-Evans rats by adding lead carbonate (4% w/w) to the diet of nursing mother immediately after delivery. The morphological and biochemical features of cerebral ontogenesis were studied in 30-day-old rats. By the 30th postnatal day, the overall effect of lead intoxication was retardation of brain growth. The mass of both the cerebral gray and white matter was appreciably reduced in the lead rats without any reduction in cell populations. While the neuronal population was preserved, the growth of neurons was reduced and their maturation retarded. The retarded neuronal growth was characterized by the limited proliferation of processes in the neuropil and by the reduction in the number of synapses per neuron. However, synaptogenesis was neither delayed nor perturbed but reduced by the limited development of neuronal dendritic fields. The myelination was altered and its cerebral content significantly reduced. The effect of lead on myelination was one of hypomyelination. The hypomyelination appears to be primarily related to retarded growth and maturation of the neuron and is not a reflection of a defect in the myelinating glia or a delay in the initiation of myelination.

Animals↗