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Biomedical subjects

S Becker

Publications and source records attributed to S Becker.

At least 361 records · Page 20Linked to original sources
PubMed1985

Phagocytosis by receptors for C3b (CR1), iC3b (CR3), and IgG (Fc) on human peritoneal macrophages.

Human peritoneal macrophages (HPM) obtained via laparoscopy were examined for the presence and functional capacity of complement and Fc receptors. Between 5 and 20 ml of peritoneal fluid containing 1-2 X 10(6) macrophages/ml was available for each study. Macrophages made up 80-95% of the cells in the fluid. Fc and C3 receptors on HPM were characterized by rosette formation with, and phagocytosis of, IgG- and C3-coated sheep erythrocytes (E). ElgG were bound by 82% and ingested by 63% of HPM, with 4-15 E ingested/HPM. The HPM formed rosettes with EC3b (56%) and EC3bi (71%) but not EC3d,g or EC3d. Antibodies to complement receptors type 1 (CR1) and type 3 (CR3) inhibited rosette formation with EC3b and EC3bi, respectively, indicating that HPM possessed separate and distinct receptors for the C3b and iC3b ligands. In 60% of the samples studied, HPM demonstrated the ability to ingest both EC3b and EC3bi, as well as ElgG. Because of the heterogeneous nature of the cells obtained in peritoneal fluid, due to their progressive change from monocytelike cells into mature macrophages, HPM were separated by 1 g velocity sedimentation into fractions of increasing maturity. They were then examined for phagocytosis via Fc and complement receptors. Fc receptor mediated phagocytosis occurred throughout the monocyte-to-macrophage maturation sequence, while the ability of HPM to ingest via CR1 and CR3 was maturation dependent, with ingestion via CR3 occurring before CR1, in a manner analogous to in vitro differentiation of monocyte-derived macrophages.

Erythrocytes↗
PubMed1985

Interferon-gamma accelerates immune proliferation via its effect on monocyte HLA-DR expression.

The effect of interferon-gamma (IFN-gamma) on antigen-induced and autologous proliferative responses has been investigated. The enhanced proliferative response, which resulted in the presence of IFN-gamma, was found to be the consequence of the increased density of HLA-DR induced on the accessory cells. The enhanced proliferation was at least partly due to a shift in the proliferation time course. The response to tetanus toxoid peaked 1-2 days earlier when IFN-gamma-treated monocytes acted as accessory cells than when untreated monocytes presented the antigen. Modulation of the level of DR by preincubation of the monocytes with anti-DR antibody with and without IFN-gamma demonstrated that both autologous and antigen-driven proliferation was influenced in proportion to the level of DR expressed at the time of stimulation. These experiments point to the importance of IFN-gamma in inducing an accelerated immune response via its effect on the density of DR expression on the accessory cell.

Adjuvants, Immunologic↗
PubMed1985

Disappearance and reappearance of resident macrophages: importance in C. parvum-induced tumoricidal activity.

We have investigated the role of resident macrophages in the early tumoricidal response to C. parvum. The bacteria were labeled with FITC and resident cells were labeled in situ with blue fluorescent covaspheres to enable subsequent monitoring of cellular changes by flow cytometry. Macrophages disappeared within 5 hr of administration of bacteria. At 24 hr, fibrinous adhesions containing double labeled macrophages were observed at numerous sites on the peritoneum. Macrophages associated with large numbers of bacteria, levels of beads similar to control animals, and elevated plasminogen activator-like activity did not reappear in washings in significant numbers until 72 hr. Thus, the large bacteria-containing cells that account for the majority of the early tumoricidal activity are likely to be derived from resident macrophages.

Animals↗
PubMed1985

Effects of season and illness on the dietary intake of weanlings during longitudinal studies in rural Bangladesh.

Longitudinal, quantitative studies of the dietary intake of 70 weanlings between five and 30 months of age from two Bangladeshi villages have been analyzed to determine the effects of season and illness on dietary intake. During 1014 days of observation, all foods consumed by the children were weighed by a field worker present in the home; 24-hour breast milk intake was estimated from 12-hour test weighings. Inter-individual differences explained 29% to 50% of the variance in consumption of selected nutrients and foods during 632 studies conducted when children were free from diarrhea and fever. Multiple linear regressions controlling for inter-individual differences indicated that 60-day seasonal periods explained a significant proportion of the variation in intake. Average energy consumption (kcal/kg/d) was approximately one-third greater during the post-harvest periods than during the pre-harvest monsoon period. Breast milk intake varied similarly even after controlling for age-related decreases. Consumption of rice and wheat, the major non-breast milk sources of energy and protein, had distinct seasonal patterns, thus limiting the overall seasonal variability in cereal intake. Older children, particularly boys, benefited more from the post-harvest relative abundance of food. The intake of most nutrients was significantly depressed by approximately 10% during febrile illnesses. Minor decreases in intake with other illnesses were not statistically significant.

Age Factors↗
PubMed1985

Identification of intracellular factor XIII in human monocytes and macrophages.

Factor XIII is a blood protransglutaminase that is distributed in plasma and platelets. The extracellular and intracellular zymogenic forms differ in that the plasma zymogen contains A and B subunits, while the platelet zymogen has A subunits only. Both zymogens form the same enzyme. Erythrocytes, in contrast, contain a tissue transglutaminase that is distinct from Factor XIII. In this study other bone marrow-derived cells were examined for transglutaminase activity. Criteria that were used to differentiate Factor XIII proteins from erythrocyte transglutaminase included: (a) immunochemical and immunohistochemical identification with monospecific polyclonal and monoclonal antibodies to Factor XIII proteins, (b) requirement for thrombin cleavage to express activity, (c) pattern of fibrin cross-linking catalyzed by the enzyme, and (d) different electrophoretic mobilities in nondenaturing gel systems. By these criteria human peripheral blood monocytes, peritoneal macrophages, and monocytes maintained in culture contain an intracellular protransglutaminase that is the same as platelet Factor XIII. The monocyte-macrophage protein is thrombin-sensitive, and under appropriate conditions there is no enzyme expression without activation of the zymogen. Both the monocyte-macrophage zymogen and enzyme have the same electrophoretic mobilities as platelet Factor XIII zymogen and enzyme. Antibody to A protein reacts with the monocyte-macrophage protein. B protein is not associated with this intracellular zymogen. By immunoperoxidase staining monocyte-macrophage protein seems to be localized in the cytoplasm, similar to the known cytoplasmic distribution of platelet and megakaryocyte Factor XIII. These procedures were also used to study populations of human granulocytes and lymphocytes, and protransglutaminase activity was not observed in these cells.

Acyltransferases↗
PubMed1984

Accentuated cyclic activation of peritoneal macrophages in patients with endometriosis.

Peritoneal fluid was collected from 107 women undergoing laparoscopic sterilization or diagnostic laparoscopy for evaluation of infertility. Cells consisting mainly of macrophages were separated and subjected to sophisticated flow fluorocytometric analysis. In this way more detailed information was obtained about activational characteristics of the pelvic macrophage population during the menstrual cycle. In normal women the macrophages, as compared to peripheral monocytes, showed evidence of elevated baseline activation, and a gradual increase in several markers occurred during the menstrual cycle. Cells increased in size, lost their ability to stain for myeloperoxidase, and increased in activity of both endoenzymes and ectoenzymes. These results suggest that female peritoneal macrophages are continuously responding to stimuli. The macrophage irritation was much more pronounced in women with mild endometriosis. This accentuated cyclic activation may represent an inflammatory response to bleeding from ectopic implants or retrograde menstruation or may be a consequence of some defect in the cell-mediated immune response in endometriosis.

Ascitic Fluid↗
PubMed1984

Influence of interferon on human monocyte to macrophage development.

The effect of interferon-alpha (Wellferon) on human monocyte to macrophage maturation in vitro has been investigated. Cell volume and three markers, acid phosphatase, leucine aminopeptidase, and phagocytosis, which increase with maturation, have been studied employing recently developed flow cytofluorometric techniques. The increase in cell volume and in the expression of all three markers was inhibited in a dose-dependent manner in monocyte cultures given 50-300 U/ml of interferon within 2 hr of culture initiation. An initial dose of 300 U/ml of interferon, removed from the cultures after 24 hr, was as effective in inhibiting the development of each of the markers as three 100 U pulses on three consecutive days, and as effective as 300 U interferon left in throughout the culture period. Histogram analysis of marker expression indicated that all monocytes, and not a subpopulation, were affected by the interferon. Cytotoxic activity of freshly isolated monocytes rapidly decayed when the cells were cultured under standard maturation conditions. The addition of interferon to the cultures prevented the loss of this activity while also preventing the development of more mature cells. It appears that maintenance of the cytotoxic state is one influence of interferons; however, it may be that these cells have also been directed toward alternate pathways of macrophage differentiation.

Acid Phosphatase↗
PubMed1984

[Attitudes and beliefs of medical and psychology students with regard to treatment with psycholtropic drugs].

Attitudes and assumptions of medical and psychology students in regard to psychotropic medication were assessed my means of a content analytic method. The students were in clinical training. Psychology students were compared with medical students. Attitudes related to psychopharmaca were compared with those related to antiepileptics. Results show that psychopharmaca are mainly criticized, that judgments are based on misinformation and presented with much emotional commitment. Negative judgements also generalize on the prescribing physicians. Consequences for the education of students are discussed.

Anticonvulsants↗
PubMed1984

Malnutrition is a determining factor in diarrheal duration, but not incidence, among young children in a longitudinal study in rural Bangladesh.

Diarrhea and malnutrition are common in young children in developing countries and a reciprocal relationship has been postulated with diarrhea leading to malnutrition and malnutrition predisposing to diarrhea. To investigate the importance of malnutrition as a determining factor in diarrheal illnesses, data were analyzed from a longitudinal community-based study done in rural Bangladesh. Children classified by nutritional status according to a variety of anthropometric indicators were prospectively evaluated for incidence, duration, and etiology of diarrhea. Children with low weight for length had longer durations of diarrhea than better nourished children; however, children of differing nutritional status had similar diarrheal incidences. The duration of diarrhea, including that associated with enterotoxigenic Escherichia coli and Shigella, increased progressively as nutritional status indicators worsened. These results suggest that nutritional interventions alone are unlikely to reduce the high incidence of diarrhea, but that efforts to improve nutritional status may have a beneficial effect on the duration of diarrhea and its unfavorable nutritional consequences.

Animals↗
PubMed1984

Effects of diarrhea associated with specific enteropathogens on the growth of children in rural Bangladesh.

Village-based surveillance data from longitudinal studies in rural Bangladesh have been used to evaluate the nutritional consequences of infectious diseases, including diarrhea due to specific pathogens. The prevalences of specific illnesses were related to the ponderal and linear growth of young children for 2-month and 1-year periods. Of the common illnesses, only diarrhea had a significant inverse relationship with increments of weight during 2-month periods and of length during 1 year. Diarrhea accounted for 20% of the difference in linear growth between the study children and the international reference population during the first 5 years of life. Diarrhea associated with enterotoxigenic Escherichia coli had a significant negative effect on the bimonthly weight gain of children in this community and shigellosis had the strongest negative effect on bimonthly and annual linear growth. Control of diarrhea due to enterotoxigenic E coli and Shigella would not only substantially diminish diarrheal morbidity but would also improve the growth of children and thereby reduce the prevalence of protein-energy malnutrition.

Bangladesh↗
PubMed1984

Interferons as modulators of human monocyte-macrophage differentiation. I. Interferon-gamma increases HLA-DR expression and inhibits phagocytosis of zymosan.

The development of HLA-DR (Ia) expression in the presence and absence of interferon-gamma was monitored in monocyte-macrophage cultures. Overnight incubation with doses as low as 5 U/ml gave elevated values for Ia expression and the maximum increase was obtained with 200 U/ml. In contrast interferon-alpha had only a slight effect on the expression of Ia at doses as high as 2000 U/ml. The increase seen at 24 hr was maintained during the first 2 days of culture. The interferon-gamma-treated cells expressed four to five times more Ia than fresh monocytes. During the same time, monocytes cultured in the absence of interferon expressed approximately two times the amount of fresh monocytes. When the surface density of Ia was calculated, the interferon-gamma-treated monocytes expressed twice that of the untreated cells. Major changes in morphology and size occurred between days 3 and 4 of monocyte to macrophage development. Consequently a rapid increase in Ia expression took place; however, when the surface density was calculated this value increased only slightly when the monocytes matured to macrophages. The interferon-gamma-treated cells continued to express more total Ia as well as having increased surface density of this antigen. Interferon-gamma was also added to monocyte-macrophages several days after culture initiation (days 3, 4, and 5). Despite being in different stages of maturation, the cells responded to the interferon with increased Ia expression and surface density. The phagocytic activity of opsonized zymosans was also monitored. In contrast to Ia expression, this activity was downregulated by interferon-gamma, and the lower levels of phagocytosis were maintained through the 7 days of observation. Thus, interferon-gamma appears to change the differentiation pathway of the monocyte. The signal stimulates an increased level of Ia that may assist in the initiation of immune responses, and at the same time downregulates the scavenger role of removing opsonized particles. Once the monocyte has received this specific signal it continues to develop in a pathway different from that of the nontreated monocytes.

Cell Differentiation↗