Biomedical subjects
Publications and source records attributed to B Glick.
An avian equivalent of the mammalian thyroid isthmus appeared in thiouracil-treated (.1% in feed from hatching to 6 and 8 weeks of age) chickens. In two experiments in which chickens were fed a diet containing thiouracil, thyroid tissue was found connecting the thyroid glands. Histological examination of the connecting tissue revealed that it was of the same cellular composition as the thyroid glands.
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Bursal secretory cells have been studied with light and electron microscope after prolonged carrageenan treatment. Intravenous injected carrageenan decreased the number of secretory cells as early as 4 days after the first carrageenan administration. Degranulation of the secretory cells may have made it difficult to identify these cells. The discharge of granules from the secretory cells was indicated by the appearance of a large amount of extracellular substance on the cell surface. The carrageenan may have accelerated the IgM-IgG switch after immunization with Salmonella O antigen. The rapid IgM-IgG switch was preceded by degranulations of the secretory cells. Therefore, the secretory products of the cells might have contributed to the switch. The number of secretory cells in the carrageenan-treated birds increased by the secondary immunization. Many of these secretory cells were immature and located close to the corticomedullary border. The young cells revealed a large blastlike nucleus and bulky cytoplasm with granules surrounding the cytocentrum and Golgi zone.
Forty-two pairs of maternal and cord plasma vitamin C levels were determined after term, preterm, and multiple gestation pregnancies and 95 determinations of plasma ascorbate were performed on 36 premature infants who were fed a recommended infant formula throughout the first month of life. There were no significant changes of the cord or maternal ascorbate levels or of the cord/maternal ascorbate ratio between term, preterm, and multiple gestation cases. A significant negative correlation was found between the maternal ascorbate levels and the cord/maternal ascorbate ratio, supporting previous observations that high fetal blood levels of vitamin C are maintained even in cases where the maternal vitamin nutrition is poor. A rapid decline from cord levels was evident during the first week of life, followed by maintenance of relatively low plasma ascorbate levels, despite supplementation of recommended vitamin nutrition. Further monitoring of ascorbate levels in premature infants is suggested for better adjustment of the recommendations for vitamin C supplementation.
We have investigated the molecular basis for a 25- to 30-fold overexpression of the c-Ki-ras oncogene in a mouse bone marrow-derived, early myeloid cell line, 416B. Southern blot hybridizations revealed that the 416B cells contain a rearranged c-Ki-ras gene in addition to an apparently normal gene. Molecular cloning and DNA sequence analyses demonstrated that the rearrangement involves the insertion of a 3.5-kilobase-pair segment of Friend virus that includes the envelope gene (env) and 3' long terminal repeat. The Friend provirus is positioned between a 5' nontranslated exon (exon phi) and the first coding exon (exon 1) of the c-Ki-ras gene in the same transcriptional orientation. Results of RNA blot analyses indicate that transcription from the rearranged gene initiates at a promoter that excludes sequences in exon phi. The data support the hypothesis that enhanced c-Ki-ras expression in the 416B cells results from integration of a Friend provirus within this gene.
Lymphoid tissue, immunity and erythropoiesis in bone marrow were studied in chickens which had received air cell applications of cyclophosphamide (Cy) between 16 and 18 days of their embryonic development. The bursae from the Cy-treated birds were reduced significantly in size, deficient in bursal follicles, and lacked lymphocytes. The agglutinin level of sheep red blood cells of birds treated with Cy (2 mg) as 16, 17 and 18-day embryos was significantly lower than controls. While these Cy-treated birds lacked IgG antibody to sheep red blood cells, about 50% of the Cy birds produced unspecific IgG. Cy treatment did not suppress the graft-versus-host response. Cy did not change the absolute number of lymphocytes, granulocytes or erythroid series of cells in the bone marrow but did eliminate plasma cells. Since some of the Cy-treated birds did not produce specific agglutinin but made Ig, one would have to conclude that the presence of the bursa was not obligatory for Ig synthesis, but that the bursal microenvironment may be a prerequisite for synthesis of specific antibody.
The development of the bursa of Fabricius was studied in normal and testosterone-treated embryos. The bursal anlage appears on the 5th day of incubation as an outgrowth of the dorso-caudal wall of the cloaca. By Day 7, the bursal lumen is present and separated from the anal invagination by a thin epithelial membrane. Shortly after this developmental state, the epithelial membrane disappears and the bursal lumen freely communicates with the amniotic cavity. The remnant of the bursal anlage forms the ventral wall of the anal invagination that is actually the bursal duct. Disappearance of the remnant of the bursal anlage, which takes place after the 16th day of incubation, allows the bursa to join the cloaca. Bursal folds appear on the 10th day of incubation. Mesenchymal cells then differentiate into dark and light cells. The dark cells, between 11 and 14 days of incubation, mobilize in the mesenchymal network and assemble in small groups under the epithelial rudiment of the folds. They, then, enter the epithelium where they induce bud formation. During the assemblage of dark cells beneath the epithelium and their emigration into the epithelium, they acquire cytoplasmic granules that resemble avian secretory cells. The light cells do not associate with the epithelium. They may be the precursors of cortical reticular cells. The differentiation of dark cells is inhibited in the presence of testosterone. Therefore, the failure of bud formation and subsequent follicular formation in the bursa of testosterone-treated embryos may be attributed to the elimination of an induction signal supplied by the differentiated dark cells of the mesenchyme.
The effects of three routes of antigen administration, intravenous, intraperitoneal, and intramuscular, were compared in New Hampshire chicks. Chicks were injected with sheep red blood cells (SRBC) or Brucella abortus (BA) at 29 or 34 days of age. Agglutinin response was determined on Days 3, 5, 7, and 12 postimmunization. Route of injection affected total antibody titers to SRBC significantly at all stages of the response. Sex and age effects were not significant. Brucella abortus antibody titers were significantly influenced by age but not by sex and route.
A recombinant library of double minute chromosomal DNA, enriched in specific sequences that are amplified in Y1 mouse adrenal tumor cells, was used as a source of material to explore the structure and expression of amplified cKi-ras genes in these cells. From DNA sequence analysis of these cloned fragments, we found no evidence for the presence of point mutations previously demonstrated to be associated with activation of the transforming potential of ras genes. A comparison of the mouse gene with that of the homologous human cKi-ras2 gene reveals 94% nucleotide sequence homology within the coding regions and 97% homology for the predicted amino acid composition. Like the human gene, the mouse cKi-ras gene contains alternative 3' coding exons. Blot hybridization analyses of RNA revealed a preferential utilization of the more 3' of the two fourth coding exons in the generation of Y1 cKi-ras transcripts.
Surgical bursectomy resulted in cellular depletion of the periellipsoid white pulp, confirming its bursa dependency. Also, in bursectomized birds, the ellipsoid could not be identified, although a small number of abnormal ellipsoid-associated cells (EAC) were observed in the periellipsoid region. The most characteristic finding was the degeneration of the EAC. Degeneration of EAC indicated that the intact bursa was mandatory for normal differentiation of cells of the periellipsoid white pulp into EAC. The promoting effect of the bursa might take place by a bursal hormone. The histological impairment of the EAC was followed by reduced carbon binding and migrating capabilities. Bursectomy resulted in a shift in bacterial phagocytosis in that many cells of the periellipsoid phagocytosed Salmonella. The reduced heterophil infiltration of the ellipsoid in bursectomized birds might be explained by the impaired granular content of the EAC. The impaired migration capability of the EAC might contribute to the low number of germinal centers in bursectomized birds.
Avian peripheral blood and embryonic spleen cells were prepared for cell flow cytometry. The Ortho Spectrum III was the flow cytometer used in these experiments. The major objectives were to identify the location of lymphocytes and granulocytes in the cytogram displayed by flow cytometry, to develop a technique which would allow the collection of granulocytes relatively free of other cell types and to characterize the cell cycle within these cell populations. The cytogram of fresh avian cells developed in the Ortho Spectrum III revealed three characteristic cell clusters. Peripheral blood or embryonic spleen cells were separated on a Ficoll-Hypaque double density gradients into two distinct layers and a pellet. Light microscopic examination revealed the top layer of cells to be primarily lymphocytes while the middle layer of cells was granulocytes. Presentation of the cells from these layers to the Ortho Spectrum III revealed that granulocytes made up Cluster 3 while lymphocytes were included in the other clusters. The Ortho Spectrum III was employed to determine the presence of G1 (pre-DNA synthesis), S (DNA synthesis), and G2/M (post-DNA synthesis and mitosis) phases of cells in Clusters 1 and 2 and Cluster 3. While all the cells from peripheral blood were in G1, the embryonic spleen revealed cells in G1, S and G2/M in both Clusters 1 and 2 and Cluster 3.
Four very-low-birth-weight infants developed localized intestinal perforations after enteral administration of indomethacin. The clinical picture and histologic findings were unlike those seen in necrotizing enterocolitis.
Neonatal intussusception in premature infants is uncommon and may mimic other abdominal disorders. We present a case of intussusception in a very low birthweight neonate. Presenting signs initially suggested necrotizing enterocolitis and meconium disease, and the diagnosis was confirmed at laparotomy.
A small, double-blind crossover study compared the efficacy of aminophylline and doxapram in ventilator weaning of eight premature infants recovering from respiratory distress syndrome (RDS). Although neither drug was significantly better than the other, four infants were weaned from mechanical ventilation after drug administration. It is suggested that drugs stimulating the respiratory center may aid in shortening the duration of mechanical ventilation in premature infants recovering from RDS.
We have described two cases in which persistent fetal circulation was mistakenly diagnosed because umbilical artery catheters were placed in too high a position. In one case, repeated doses of tolazoline were given unnecessarily. While high placement of umbilical artery catheters is commonly accepted, misplacement may not always be apparent on routine AP chest films taken to confirm catheter positioning.
We have described the lymphocyte migration through the sinus wall of the lymph node. The sinuses showing lymphocyte migration are located in a given area of the node that might be comparable with the T-dependent deep cortex of the mammalian lymph nodes. The lymphocyte migration takes place through the cytoplasm of the endothelial cell presumably by formation of the transendothelial channels, which are produced by vesicles of the endothelial cell. The intensive vesiculation preceding the formation of transendothelial channels might indicate the direction of the migration. The absence of vesicles in the endothelial cell and the dilated intercellular space between the lymphocyte and endothelial cell suggest that the lymphocyte in the sinus wall may be "resting". The presence of the multivesicular body in the pseudopod or in the vicinity of the pseudopod of the lymphocyte may contribute to the migration.
Cell flow cytometry was used to assess the life cycle of embryonic lymphocytes. Cells were prepared for flow cytometry by fixation for 30 min in a final concentration of 70% ethyl alcohol, treated with ribonuclease (50 to 70 Kunitz/ml) and incubated for 30 min. in propidium iodide. Our data demonstrated that bursal lymphocytes from 20-day embryos (DE) exhibited significantly fewer cells in pre-DNA (deoxyribonucleic acid) and more cells in DNA synthesis (S) than thymic cells from 20 DE, and thymic lymphocytes from 16 DE expressed a more active S than bursal cells. Lymphocytes were separated from granulocytes by a Ficoll-hypaque double density gradient. The DNA cycle of bursal lymphocytes was more easily disrupted with cyclophosphamide (Cy) than the DNA cycle of thymic lymphocytes. However, unfractionated splenic cells from embryos treated with Cy revealed a greater percentage of cells in S and post-DNA synthesis and mitosis than splenic cells from control embryos. Because the splenic cells of Cy-treated embryos were predominantly immature granulocytes, it was concluded that Cy stimulated myelopoiesis in the spleen.
Analysis in a cell flow cytometer (Ortho Spectrum III, Ortho Inst.) of single cell suspensions from the bursa and thymus of 20-day embryos revealed two distinct cell clusters. The two clusters were less apparent after fixation of the cells in paraformaldehyde and assumed a comet-like appearance at 30 min fixation in ethyl alcohol (EA). The G (postmitotic), S [deoxyribonucleic acid (DNA) synthesis], and G2/M (premitotic and mitotic) phases of the life cycle were visualized in two cell flow cytometers (Ortho Spectrum III and FACS IV, Bectin Dickinson) after treating the cells with EA, ribonuclease (RNase), and propidium iodide (PI, a fluorescent dye). Bursal cell suspensions exposed to the EA-RNase-PI protocol and stored for 3 weeks in phosphate-buffered saline showed minor changes in the G1 coefficient of variation, G1, and S percentages, but marked changes in these parameters occurred after 6 weeks of storage. Thymic cells treated in a similar fashion could not be maintained for 3 weeks. Bursal and thymic cells may remain in the EA for one day and possibly as long as 7 days prior to preparing them for DNA life cycle analysis. Paraformaldehyde was not a satisfactory cell fixative for assessing a cell's DNA life cycle.