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Biomedical subjects

I M Shapiro

Publications and source records attributed to I M Shapiro.

At least 127 records · Page 7Linked to original sources
PubMed1980

Bone solubilization by mononuclear cells.

Mononuclear cells derived from chicken peripheral blood or from thioglycollate-induced mouse peritoneal exudates were found to cause calcium release from devitalized homologous bone in vitro. These mononuclear cells with osteolytic activity were adherent to plastic surfaces and were identified as being macrophages by cell surface markers and histochemical staining. Other mononuclear cells such as chicken thymocytes, nonadherent peripheral blood mononuclear cells, and chick embryo fibroblasts did not cause bone dissolution. In parallel with the active solubilization of bone mineral, 14C-label was also released from devitalized calvaria prelabeled with 14C-proline. Macrophages, inactivated by repeated freezing and thawing as well as those cultured in the presence of iodoacetate, did not solubilize bone in vitro. The degree of bone solubilization was directly related to the numbers of macrophages per culture as well as the duration of the culture period. Powdered devitalized homologous bone was used in most experiments, but macrophages were also able to solubilize bone material in vitro from devitalized calvaria and bone slabs. The addition of Escherichia coli lipopolysaccharide to cultures of bone and macrophages significantly increased the levels of calcium released from bone. The addition of parathyroid hormone and calcitonin had no effect on macrophage-mediated bone dissolution. These results suggest that viable macrophages have osteolytic activity and that this activity is modulated by an inflammatory mediator, endotoxin.

Animals↗
PubMed1979

Relationship between Epstein-Barr virus genome number, amount of nuclear antigen, and early antigen inducibility in diploid and tetraploid lymphoma cells of related origin.

In a collection of near-diploid and near-tetraploid Raji sublines and somatic Raji/Raji hybrids a linear relationship was found between the number of Epstein-Barr virus (EBV) genome copies and the relative amount of EBV-determined nuclear antigen per cell. Inducibility of the viral cycle by iododeoxyuridine and by P3HR-1 virus superinfection coulb be related to the number of resident EBV genome copies per haploid target cell. The implications of these findings are discussed.

Antigens, Viral↗
PubMed1978

Ca2+ transport by chondrocyte mitochondria of the epiphyseal growth plate.

In a study of the Ca2+ kinetics of mitochondria of chick epiphyseal chondrocytes, the rate of Ca2+ uptake was linear up to a medium Ca2+ concentration of 30 mum. The half maximal transport rate occurred at 34 mum Ca2+. The Ca2+ uptake rate, expressed as a function of time, was 35 nmoles/mg protein/min; the presence of Mg2+ had little effect on Ca2+ accumulation. While these kinetic parameters did not differ significantly from mitochondria of cells of nonmineralizing tissues, the respiratory characteristics of the chondrocyte organelles exhibited functional differences. Thus, up to 350 nmoles Ca2+/mg protein, chondrocyte mitochondria performed coupled oxidative phosphorylation. Calcium uptake was energy supported, while Ca2+ binding was low. Addition of respiratory inhibitors and uncouplers to these mitochondria resulted in a rapid loss of more than 80% of the total Ca2+. The Ca/Pi ratio of the extrudate was very similar to the ratio of the ions in cartilage septum fluid. In the most mineralized zones of the epiphyseal plate, there was little change in the state 4 respiratory rate, but nonspecific Ca2+ binding was elevated and a high percentage of the total Ca2+ was in a nonextrudable form. The results indicate that in cells preparing for mineralization, much of the total mitochondrial Ca2+ is in a form that can be transported to the calcification front. In cells close to the calcification front, nonextrudable Ca2+ may form calcium phosphate granules described by other investigators.

Animals↗
PubMed1978

X-ray fluorescence analysis of lead in teeth of urban children in situ: correlation between the tooth lead level and the concentration of blood lead and free erythroporphyrins.

The tooth lead level of 30 lead-exposed children was measured in situ using an X-ray fluorescence technique. The tooth lead concentration divided by the child's age correlated with the free erythroporphyrin (FEP) (r = 0.51) and the blood lead levels (r = 0.31). The mean tooth lead concentrations of 10 Class IV children (FEP greater than or equal to 190 micrograms/100 ml; blood lead 30-80 micrograms/ml) was 14.5 +/- 5.5 ppm/year. Reexamination of the histories of children who had been classified as Class II or III, but who had tooth lead concentrations within 1 SD of the Class IV level, indicated that many of these children could also be considered to be Class IV children. When the x-ray fluorescence technique was used to screen an urban population of 300 children, the tooth lead values indicated that 72% of the children had been exposed to low levels of environmental lead. Six percent of the children were found to have tooth lead concentrations in excess of 9 ppm/year and within 1 SD of the mean value exhibited by Class IV children. These children were considered to have a high body lead burden. The percentage of children having an elevated tooth lead level is similar to the number previously reported using exfoliated deciduous teeth.

Child↗
PubMed1978

The HLA-dependent expression of testis- organizing H-Y antigen by human male cells.

The proposal that the stable expression of organogenesis-directing plasma membrane antigens, such as testis-organizing H-Y antigen, requires beta2-microglobulin-MHC antigen dimers as anchorage sites was tested on Daudi human Burkitt lymphoma cells [46, XY, 15q-, 14q+, beta2-m(-), HLA(-)]. The H-Y antigen level of Daudi was only 20% of that of Raji and Ramos, two human male pseudodiploid Burkitt lymphoma lines that were beta2-m(+), HLA(+). When Daudi is hybridized with beta2-m(+), HLA(+) cell lines, beta2-microglobulin, supplied by the latter, is known to restore the expression of Daudi HLA antigens A10 and BW17. Such restoration of HLA antigen expression markedly elevated H-Y antigen levels in those somatic hybrids. Thus the H-Y antigen level of the Daudi x Raji 8A (male X male) hybrid became equal to that of TetraRaji--the colcemide-induced Raji tetraploid line. Two independently derived Daudi x Hela D98 (male x female) hybrids, DAD 1 and DAD 10, demonstrated even higher H-Y antigen levels comparable to that of normal male peripheral blood lymphocytes.

Antigens↗
PubMed1978

Polyploidization of Epstein-Barr virus (EBV)-carrying lymphoma lines decreases the inducibility of EBV-determined early antigen following P3HR-1 virus superinfection or iododeoxyuridine treatment.

Four tetraploid cell lines were derived from the Epstein-Barr virus (EBV)-carrying, nonproducer Burkitt lymphoma line Raji after colcemide treatment. EBV early antigen (EA) was induced by P3HR-1 virus superinfection and by iododeoxyuridine treatment. Inducibility was reduced in all tetraploid lines compared to the near-diploid counterpart. The average number of EBV genome equivalents per tetraploid cell was 60-70, compared to 50 in diploid cells. This contrasts with the EBV genome amplification previously observed in somatic cell hybrids.

Antigens, Viral↗
PubMed1977

Measurement of lead content of children's teeth in situ by x-ray fluorescence.

The central nervous system of young children is particularly sensitive to neurological damage due to excessive lead exposure. The lead stored in a tooth is permanent and related to the quantity of ingested lead. The lead is assayed by measuring the characterisitc radiation from lead in a tooth in situ irradiated with gamma rays from a cobalt-57 source. The sensitivity of the method is adequate to measure lead levels commonly associated with environmental background. The X-ray exposure to the tooth necessary for this determination is approximately one tenth of that required for a routine dental examination.

Child↗
PubMed1975

Blood-lead levels of monkeys treated with a lead-containing (N2) root canal cement: a preliminary report.

The effect of a root canal filling material on the level of lead in blood of rhesus monkeys was examined by anodic stripping voltometry. Blood-lead levels after root canal treatment with N2 cement were elevated when compared to preoperative controls. Lead 210 was incorporated into the leadfree N2 cement to identify the source of lead. Analyses of blood samples for 210Pb indicated that the lead originated from the filling material.

Animals↗
PubMed1975

Dental lead, blood lead, and pica in urban children.

Lead storage in teeth was evaluated by examining the lead concentration in deciduous teeth of 32 children whose habits of pica and state of lead exposure had been studied when they were between 1 and 3 years of age. Concentratios of lead in their teeth depended on the reported amount of paint or plaster intake and the duration of exposure. The mean dental concentration of lead in exposed children was significantly higher than the mean value in 36 controls, who presumably did not have undue exposure to lead. A difference in dental lead concentration related to living area was noted. The significant difference in lead content of teeth between the two groups, even though the concentrations of lead in blood at 8 years of age were similar, emphasizes the importance of dental lead measurments for retrospective studies of lead exposure.

Calcium Sulfate↗
PubMed1975

The lead content of teeth. Evidence establishing new minimal levels of exposure in a living preindustrialized human population.

Teeth were collected from populations differing in their degree of industrialization and from prehistoric populations. Lead analysis of dentine revealed that in contemporary teeth the lead level was related to the degree of industrialization and that in prehistoric teeth very low concentrations of lead were present. Because tooth lead reflects the body burden of lead, this result suggested that the prehistoric populations and modern nonindustrial populations were exposed to environments low in lead. Teeth from a contemporary population of nonindustrialized Indians of the Lacandon forest in Mexico contain lead in concentrations comparable with those of the prehistoric populations. Comparison of the Indian teeth with teeth from a modern industrial population reveals a 45-fold difference in median tooth lead level. This finding lends support to the hypothesis that high levels of urban lead pollution result in elevated body burdens of lead.

Adult↗