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Biomedical subjects

I M Shapiro

Publications and source records attributed to I M Shapiro.

At least 109 records · Page 6Linked to original sources
PubMed1983

Infection of normal human epithelial cells by Epstein-Barr virus.

Primary cultures of epithelial cells were grown from the tonsils and adenoids of patients with diseases not related to Epstein-Barr virus. The cells could not be infected by Epstein-Barr virus. Fluorescein-labeled Epstein-Barr virus and a cytofluorograph were then used to show that the epithelial cells do not have detectable receptors for the virus. However, implantation with Epstein-Barr virus receptors gave the cells the ability to bind the labeled virus. One to 5 percent of receptor-implanted cells exposed to the transforming B95-8 substrain of the virus expressed Epstein-Barr nuclear antigen. The early and viral capsid Epstein-Barr virus-determined antigens were not detected in the virus-infected cultures. The results show that normal human epithelial cells from the nasopharynx become susceptible to infection by Epstein-Barr virus when the membrane barrier resulting from the lack of viral receptors is overcome by receptor implantation.

Cells, Cultured↗
PubMed1983

Studies of nucleotides of growth-plate cartilage: evidence linking changes in cellular metabolism with cartilage calcification.

The objective of this study was to examine the nucleotides of chick growth-plate cartilage and to measure the concentration of adenine nucleotides in the pre-mineralizing and mineralizing zones. Nucleotides were isolated from the two regions using a rapid-freezing technique and the concentration of individual components was ascertained by HPLC. The actual values of ATP, ADP, and other nucleotides in cartilage was low. The lowest values were recorded in the mineralized zone. In this latter zone the energy charge ratio and the ATP/ADP ratio were depressed. This was probably due to 02-related inhibition of mitochondrial oxidative activity. Additionally, the percentage of octanoate, a short-chain fatty acid that accumulates when aerobic metabolism is disturbed, was found to have increased in the calcifying zone. These findings suggest that calcification of cartilage is associated with hypoxia-related modulation of chondrocyte metabolism.

Animals↗
PubMed1982

Initiation of endochondral calcification is related to changes in the redox state of hypertrophic chondrocytes.

The level of pyridine nucleotides (NADH and NAD+) in the mineralizing growth plate of the chick was ascertained by high-resolution scanning microfluorimetry and biochemical analysis. Scanning electron microscopy and light microscopy were used to relate the concentrations of NADH and NAD+ to stages of chondrocyte maturation. A dramatic increase was found in the relative concentration of reduced pyridine nucleotides in the hypertrophic zone. On either side of this zone, in proliferating and calcifying cartilage, there was a decrease in NADH fluorescence, and the NADH/NAD+ ratio was depressed. The finding that NADH accumulated in the tissue zone associated with the earliest deposition of bone mineral supports the hypothesis that a change in the redox state initiates tissue mineralization.

Animals↗
PubMed1982

Neurophysiological and neuropsychological function in mercury-exposed dentists.

In a study of the relation between cumulative exposure to mercury and chronic health impairment 298 dentists had their mercury levels measured by an X-ray fluorescence technique. Electrodiagnostic and neuropsychological findings in the dentists with more than 20 micrograms/g tissue mercury levels were compared with those of a control group consisting of dentists with no detectable mercury levels. 30% of the 23 high mercury dentists had polyneuropathies. No polyneuropathies were detected in the control group. The high mercury group had mild visuographic dysfunction; they also had more symptom-distress than did the control group. These findings suggest that the use of mercury as a restorative material is a health risk for dentists.

Adult↗
PubMed1982

Epstein-Barr virus (EBV) receptor implantation onto human B lymphocytes changes immunoglobulin secretion patterns induced by EBV infection.

Mosaic membrane vesicles containing both Epstein-Barr virus (EBV) receptors and Sendai virus envelope proteins were allowed to form by the previously described membrane solubilization and co-reconstitution technique. The vesicles were allowed to fuse with the membranes of normal human B lymphocytes, whereafter the cells were infected with transforming EBV (B95-8 substrain). Compared to similarly infected but otherwise unmanipulated cells, the receptor-implanted lymphocytes responded with a larger number of EBV-determined nuclear antigen positive and immunoglobulin-secreting plaque-forming cells (PFC). Moreover, there was a clear increase of the IgG/IgM PFC ratio in the receptor-implanted B lymphocytes. These results show that not all human B lymphocytes that can potentially be activated by EBV express functional EBV receptors. B lymphocytes programmed to secrete IgG appear to be more defective in this respect than IgM secretors.

Antibody-Producing Cells↗
PubMed1981

Epstein-Barr virus co-reconstituted with Sendai virus envelopes infects Epstein-Barr virus-receptor negative cells.

Epstein-Barr virus (EBV) was co-reconstituted with Sendai virus envelopes. The reconstituted "hybrid' virus could bind and penetrate into EBV-receptor negative cells. Using this approach, T-cell-derived human and mouse leukemia cells, human T-lymphocytes and mouse spleen cells were successfully infected as judged by the induction of EBV-determined antigens and stimulation of DNA synthesis. The T-cell-derived human leukemia line Molt-4, that can absorb EBV but without virus penetration, could be also infected by the reconstituted EBV.

Animals↗
PubMed1981

The detection of Epstein-Barr virus receptors utilizing radiolabelled virus.

Epstein-Barr virus (EBV) was labelled with 3H-thymidine and purified about 1000-fold from the culture medium by ultracentrifugation on 5 to 30% dextran gradients. The presence of the virus was monitored by radioactivity and Epstein-Barr virus-determined nuclear antigen (EBNA) induction in sensitive indicator cells (Ramos). Peaks for both activities occurred in the 17 to 18% dextran fractions. Unlabelled virus recovered in the peak fraction was labelled with 125I. Both thymidine and 125I-labelled purified virus bound quantitatively to receptor-positive Burkitt lymphoma-derived cell lines but not to EBV-receptor-negative T-lymphocyte-derived cell lines. Thymidine-labelled virus that was allowed to bind to Raji cells was present in the interior of briefly trypsinized cells after 3 h incubation at 37 degrees C. The results provide a convenient method for detecting the EBV receptor by radioactively labelled virus.

Burkitt Lymphoma↗
PubMed1980

Lack of Fc receptors on osteoclasts.

Fc and C3 receptors, which are characteristically present on macrophages, could not be demonstrated on osteoclasts maintained in situ on their normal substrates when assayed for by use of sheep red blood cells coated with immunoglobulin (Shapiro et al. 1979). The present study tested the hypotheses that Fc receptors are present only on the osteoclast surface adjacent to bone and that Fc receptors on osteoclasts can be uncovered by enzymes or stimulated to appear. Freeze-dried, inverted osteoclasts (and osteoblasts) obtained from the endocranium of newborn rats were tested for Fc receptors using the rosette assay and examined by scanning electron microscopy. No rosettes were observed on the surfaces of the osteoclasts that had been approximal to the bone. Bone specimens were cultured for 30 min at 37 degrees C in control medium, or in medium with the addition of 10, 50 or 100 microgram/ml trypsin, 0.5 U/ml parathyroid extract (PTE), or 0.5 or IU/ml parathyroid hormone 1--34 (PTH). Additionally, two week-old rats were injected intraperitoneally with PTE (1.5 U/g body weight or 1 USP/g body weight) or with PTH (1 U/g body weight) or with vehicle alone, 6 h before sacrifice. The specimens were assayed for Fc receptors and examined by scanning electron microscopy. Macrophages were always used as controls for the assay. No rosettes were present on osteoclasts subjected to any of these treatments. Accordingly, the hypotheses were not supported.

Animals↗
PubMed1980

Energy dispersive X-ray elemental analysis of isolated epiphyseal growth plate chondrocyte fragments.

Isolated cells of matrix fragments of freeze fractured and freeze dried growth plate from the four species was analyzed by EDX. Cells were removed from the tissue by stereoscopic microdissection using an SEM and mounted on thin film supports on TEM grids: this approach eliminated specimen X-ray background and reduced instrumental and support background levels to insignificant proportions. Chondrocyte and matrix fragments were dissected and analyzed. Cell Ca reaches EDX detectable levels in hypertrophic cells close to the mineralization front. At all stages of maturation, the cells exhibit high P; however, matrix Ca levels are elevated before P. This data suggests that the early cartilage matrix is accumulating Ca and that the cells' role in this process may be to elevate the matrix Ca and P concentration. All cells showed clear S peaks although these are reduced in late hypertrophic cells. With mineralization, matrix S levels fall, indicating a loss of sulfated proteoglycans. Matrix before mineralization contains more K than would be expected from data of previous studies. It is suggested that while this K may be bound to fixed anionic sites in the matrix, reported values for cartilage lymph and extracellular fluid should be reviewed.

Animals↗
PubMed1980

Transfer of Epstein-Barr virus receptors to receptor-negative cells permits virus penetration and antigen expression.

Epstein-Barr virus (EBV) receptors were implanted into the membranes of receptor-negative cells, using Sendai virus envelopes as vehicles. The presence of the receptors in the target cell membrane was demonstrated by monitoring the fate of radioiodinated donor membranes. Receptors could be detected for at least 36 hr after implantation. [3H]Thymidine-labeled EBV bound efficiently to receptor-implanted cells but not to control cells. Binding was inhibited by an excess of nonlabeled virus. Of the [3H]thymidine-labeled EBV DNA, 50-75% was found inside the receptor-implanted, EBV-exposed cells 24 hr after the infection. The viral genome was functionally active in B lymphocyte-derived cell lines of human, murine, and baboon origin; in T lymphocyte-derived lines of human and murine origin; in mouse fibroblasts; and in freshly explanted mouse lymphocytes, as shown by the expression of EBV-determined nuclear, early, and viral capsid antigens.

Animals↗