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Biomedical subjects

S Becker

Publications and source records attributed to S Becker.

At least 415 records · Page 23Linked to original sources
PubMed1980

Antral gastrin concentration in gastric ulcer disease. The finding of high concentrations in a few patients.

Antral gastrin concentratin (AGC) was measured in forceps biopsy specimens of prepyloric mucosa obtained at endoscopy in 65 patients with various kinds of gastric ulcer and in 31 nonulcer control patients. AGC in 32 patients with a lesser curvature gastric ulcer, 10.0 +/- 2.0 (mean +/- 1 SE) ng gastrin/mg tissue was significantly less (P < 0.01) than AGC in 31 nonulcer control patients, 14.4 +/- 1.4. AGC was similar to the control values in 23 patients with a pyloric channel ulcer, 15.2 +/- 1.7; 5 patients with a greater curvature ulcer, 15.0 +/- 4.8; and 3 patients with both duodenal and gastric ulcers, 15.8 +/- 0.7. AGC was significantly greater (P < 0.01) than the control values in 3 patients with a vagotomy and pyloroplasty and a gastric ulcer, 29.8 +/- 5.0. In contrast with most lesser curvature gastric ulcer patients who had low AGC, 3 gastric ulcer patients had antral gastrin values which were about three times the mean AGC of the controls. Two of these patients had fasting serum gastrin values which were more than twice the mean control fasting serum gastrin. Meal-stimulated integraed gastrin responses in these 3 patients ranged from three to nine times the mean control response. These findings suggest that a high AGC may account for a few instances of increased serum gastrin concentrations in gastric ulcer patients.

Adult↗
PubMed1980

Defective cytotoxic T-cell generation in Moloney murine sarcoma virus-infected A/Sn mice.

Cytotoxic T-cells (CTL) could not be detected in spleen cell suspensions from Moloney murine sarcoma virus (M-MuSV)-induced tumor-bearing A/Sn and (A/Sn X C57BL/6) F1 mice, with the A/Sn-derived natural killer (NK)-sensitive YAC-1 lymphoma cells used as targets. However, spleen T-cells from tumor-bearing (A/Sn X C57Bl/6)F1 mice were efficient killers against C57BL/6-derived RBL-5 cells. When tested for viral antigens by sera from mice with regressing atumors, YAC-1 and RBL-5 cells cross-reacted. The anti-RBL-5 effect of spleen cells from A/Sn X C57BL/6)F1 tumor bearers was blocked in cold target competition experiments by YAC-1 cells, which suggested the expression of a CTL target structure on YAC-1 cells. The activity against YAC-1 cells in spleen suspensions of both tumor-bearing and control (A/Sn X C57BL/6)F1 mice seemed to be an NK phenomenon entirely, because blocking occurred neither with RBL-5 cells nor with freshly prepared YAC lymphoma cells, both of which have low sensitivity to NK effects. Spleen cells from (A/Sn X C57BL/6)F1 regressors were stimulated to a secondary CTL response in vitro by YAC-1 and RBL-5 cells, which further indicated that YAC-1 cells express the M-MuSV-specific CTL target structure. These experiments also showed that YAC-1 cells could be lysed by CTL. YAC-1 cells did not induce a secondary response in A/Sn regressors, which indicated a lack of M-MuSV-induced CTL memory cells in this strain. The result was not due to a general unreactivity of A/Sn mice against YAC-1 cells, because spleen cells from YAC-1-immunized mice exhibited strong T-cell-mediated anti-YAC-1 activity after in vitro cultivation. Thus tumor regression seems to occur without the production of CTL in A/Sn mice.

Animals↗
PubMed1980

Mathematical model of steroidogenesis in rat and rabbit testes.

The purpose of this study was to develop a mathematical model of testicular steroidogenesis which could not only predict steroid secretion but also could be implemented to test the validity of assumptions used in studies of testicular testosterone biosynthesis in rats and rabbits. Since the two predominant fates of testicular steroids are metabolism and secretion, we hypothesized that the data for construction of the model could be observed testicular steroid secretions and that these data could then be used to elucidate intratesticular steroid conversions. Equations based on steroid secretion by testes perfused in vitro were developed to estimate transition probabilities corresponding to steroid secretion or conversion. The model was tested by comparing the predicted steroid secretion rates with those observed for control testes perfused in vitro. In addition, the transition probabilities determined by the model were used to indicate the predominant series of reactions for converting pregnenolone to testosterone. The results presented herein confirm the capability of the model to predict steroid secretion rates and to predict preferred pathways for testosterone biosynthesis in maximally stimulated testes perfused in vitro. Moreover, the model construction required only algebra and steady-state measurements.

Animals↗
PubMed1980

Non-T-cell-mediated cytotoxicity in mice with tumors induced by Moloney murine sarcoma virus (M-MuSV). II. Granulocyte-mediatd cytotoxicity against autochthonous target cells isolated from M-MuSV-induced tumors.

Experiments were performed in A/Sn and A/WySn mice to determine the specificity, organ distribution, and further characteristics of the small non-T-cells that infiltrate Moloney murine sarcoma virus (M-MuSV)-induced tumors and are capable of killing the autochthonous M-MuSV-infected tumor target cells. Continuous bovine serum albumin density gradient separation proved to be the most effective method of enriching the cytotoxic cells. Increase in cytotoxic activity, measured by both the 51Cr release assay and the microcytotoxicity test, paralleled the increase in the proportion of polymorphonuclear leukocytes in mice bearing M-MuSV-induced tumors also contained myeloperoxidas-positive cytotoxic effector cells. The cytotoxic activity appeared to be nonspecific. Various mouse tumor lines as well as allogeneic fibroblasts were sensitive to these effector cells. The only target cell type not affected was the syngeneic fibroblast. In addition to the tumor mass, cytotoxic cells were found in the bone marrow, blood, and spleens of mice bearing M-MuSV-induced tumors. Only bone marrow cells from normal mice exhibited cytotoxic activity. Thus cells of the myelopoietic series may be important in fighting M-MuSV-induced tumors by way of their direct cytotoxic effects on the infected cells.

Animals↗
PubMed1979

Studies of the psychosocial adjustment of the hearing-impaired: I. Adolescents and their families a pilot study.

There is a general pessimistic view found in the literature that defends a hypothesis that the consequences of a severe hearing impairment on psychosocial development aare many and severe. This pilot study of 20 adolescents who had experienced a profound hearing impairment from birth had the purpose of clarifying this issue. The findings of the study were not compatible with such pessimism. It is concluded that the teaching of an oral means of communication which facilitates education within a mainstreamed system, is compatible with good psychosocial adjustment. To confirm this optimism and to delineate the variables in good development, further study employing comparison groups is needed.

Achievement↗
PubMed1979

Imitation in EMR boys: model competency and age.

The effects of model age and competence on the imitation behavior of 80 EMR boys were investigated. Subjects viewed a videotape in which either an adult or a peer performed a motor task with either high or low competence. In addition, the models engaged in four different kinds of off-task social behavior. The results indicated that the boys imitated the off-task social behavior emitted by high-competent and peer models more than low-competent and adult models. In addition, high-competent models were imitated more than were low-competent models on the motor-skill task, but no significant age effect was found. The efficacy of modeling as an instructional strategy was discussed, and we concluded that EMR boys should be exposed to competent models, especially peers, who emit a repertoire of adaptive behavior.

Age Factors↗
PubMed1978

Immune responses to weakly immunogenic virally induced tumors. I. Overcoming low responsiveness by priming mice with a syngeneic in vitro tumor line or allogeneic cross-reactive tumor.

This report describes model systems which show low primary in vitro syngeneic cytotoxic responses to a Moloney-induced YAC tumor (syngeneic in A mice) and a Rauscher-induced RBL5 tumor (syngeneic in C57BL/6 mice) and examines different approaches to overcome these defects. Two major findings were obtained: (a) spleen cells from A mice, injected with tumor cells from an in vitro tumor line YAC-1, derived from YACL, could generate a significant syngeneic cytotoxic response. In contrast, spleen cells from A mice injected with tumor cells from the in vivo tumor line failed to generate a syngeneic cytotoxic response. Thus, tumor cells from the in vitro line were more immunogeneic that those from the in vivo line. (b) Spleen cells from A mice which were injected with the cross-reactive allogeneic tumor RBL5, could generate significant cytotoxic responses to the syngeneic tumors YAC and YAC-1. Similarly, spleen cells from C57BL/6 mice injected with the cross-reactive allogeneic tumor YAC-1, could generate a significant cytotoxic response to the syngeneic tumor RBL5. Thus, cross-reactive allogeneic tumors could stimulate syngeneic cytotoxicity. The theoretical and the practical implications of these studies are discussed.

Animals↗
PubMed1978

Platelet activation: a new biological activity of guinea-pig C3a anaphylatoxin.

3H-serotonin-release from labelled gp-platelets is established as a sensitive method for testing a new biological activity of gp-C3a anaphylatoxin in an autologous situation. Time-, dose- and temperature-dependent release reactions as well as specific inhibition by carboxypeptidase B and anti-C3a antibodies show that C3a is a potent and specific inducer of platelet activation. Inactive C3a does not induce 3H-serotonin-release but specifically inhibits the action of C3a on platelets.

Anaphylatoxins↗
PubMed1978

Demonstration of high-affinity binding sites for C3a anaphylatoxin on guinea-pig platelets.

3H-serotonin release from guinea-pig platelets was demonstrated to be the consequence of C3a binding to these cells. A Scatchard analysis of dose-response data of the 125I-C3a binding pattern to guinea-pig platelets pointed to the existence of binding sites with high and low affinity for the C3a molecule (HA and LA receptors). HA receptors are specific for C3a with intact C-terminal arginine. whereas C3adesarg only interacts with LA receptors. The release of serotonin may be induced by a combined reaction of C3a with HA receptors and LA receptors on the platelet membrane.

Anaphylatoxins↗
PubMed1978

Modulation of sensitivity to natural killer cell lysis after in vitro explantation of a mouse lymphoma.

On the basis of studies indicating that natural killer (NK) cells of the mouse can selectively kill certain syngenetic, allogeneic, and xenogeneic tumor cells in short-term Cr release assays and that cell lines established in vitro are more sensitive than the corresponding ascites tumor cells passaged in vivo, the kinetics of the modulation to increased sensitivity was studied after in vitro explanation of the A/Sn mouse-derived YAC ascites lymphoma. Sensitivity to NK lysis appeared after 3 weeks of culturing and reached the level of the continuously cultured line after 2 months. With the more sensitive competition assay, a change could be demonstrated as early as 2--24 hours of culture. The expression of the Moloney murine leukemia virus-determined, cell-surface antigen, measured by quantitative absorption with intact cells, increased in parallel with the NK sensitivity. In contrast, the H-2 alloantigen concentration decreased during in vitro culture.

Animals↗