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Biomedical subjects

R Ber

Publications and source records attributed to R Ber.

At least 37 records · Page 2Linked to original sources
PubMed1989

Carp growth hormone: molecular cloning and sequencing of cDNA.

cDNA clones of the fish Cyprinus carpio growth hormone (GH) mRNA have been isolated from a cDNA library prepared from carp pituitary gland poly(A)+RNA. The nucleotide sequence of one of the carp GH cDNA clones containing an insert of 1164 nucleotides (nt) was determined. The cDNA sequence was found to encode a polypeptide of 210 amino acids (aa) including a signal peptide of 22 aa and to contain 5' and 3' untranslated regions of the mRNA of 36 and 498 nt, respectively. The carp GH presents a 63% amino acid sequence homology with the salmon GH, has structural features common with other GH polypeptides of mammalian or avian origin and contains domains of conserved sequence near the N- and C-terminal regions. Southern blot hybridization of carp genomic DNA with GH cDNA probes shows the presence of at least two GH-coding sequences in the fish genome.

Amino Acid Sequence↗
PubMed1989

Extinction of expression of the translocated myc gene in somatic cell hybrids between mouse myeloma and L-cells.

Most murine plasma-cell tumors show a t(12;15) reciprocal chromosomal translocation which truncates the first exon of one of the myc gene alleles and fuses it to one of the switch regions of the immunoglobulin (Ig) heavy-chain locus. This results in constitutive activation of the translocated myc gene and the production of smaller-sized mRNA molecules, which are initiated at new sites in the first myc intron. The normal myc allele is not expressed in these myeloma cells. We have studied the expression of the translocated myc gene in somatic cell hybrids between mouse myeloma and L-cells. Our previous findings show that Ig gene expression is extinguished in such hybrids. In the present work we found that the hybrids contain the normal and translocated myc genes. In contrast to the myeloma parental cells which express the translocated myc gene, the hybrids are similar to the L-cells in expressing only the normal myc allele. Our results suggest that the L-cell, fibroblast-like phenotype, is dominant in these hybrids, and show that the translocated myc gene is expressed in a tissue-specific manner in the context of the myeloma cell, and is not expressed when subjected to a fibroblast-like cellular environment.

Alleles↗
PubMed1989

Increasing empathy among medical students.

The objective of the research was to evaluate the short- and long-term effectiveness of teaching medical students interviewing skills. Methods of teaching communication skills included a workshop for clinical instructors, as an indirect approach, a workshop for medical students, as a direct approach, and a combination of both. Results demonstrated that in order to stimulate medical students to use supporting-interview skills, they themselves should participate in an interpersonal skills workshop. Being taught these skills by teachers who have participated in the workshop does not have the same positive effect.

Clinical Clerkship↗
PubMed1988

Dominance of resistance to the cytocidal effect of tumor necrosis factor in heterokaryons formed by fusion of resistant and sensitive cells.

The mechanisms underlying differences in vulnerability to the cytocidal effect of TNF, among various cell lines and strains, were explored by examining the response to TNF of heterokaryons formed by fusing TNF-resistant and -sensitive cells. Several combination pairs of human and murine cells, differing significantly in response to TNF toxicity, yet expressing a similar level of TNF receptors, were examined. In all combinations tested, the heterokaryons exhibited resistance to TNF toxicity, comparable, in extent, to that of the more resistant of the two parental cell lines. This dominance of resistance suggests that differences in vulnerability to TNF toxicity reflect activities which are expressed by resistant cells and are deficient in vulnerable ones, activities which perhaps protect the cell against the cytocidal effect of TNF.

Animals↗
PubMed1988

Consistent patterns of changing hormone responsiveness during continuous culture of cloned rat calvaria cells.

The loss of responsiveness to hormones in cell populations is a fundamental problem in cell biology and aging. We have studied this process in cloned rat calvaria (RC) bone cell populations maintained in exponential growth in long-term culture in alpha-minimal essential medium supplemented with fetal bovine serum. At various times after cloning, the populations were tested for their ability to respond to parathyroid hormone (PTH), prostaglandin E2 (PGE2), and L-isoproterenol (IPT) with an increase in intracellular cAMP. Clone RCB 2.2, which was originally responsive to PTH but not PGE2, maintained this characteristic throughout 14 mo of culture, after which PTH responsiveness was gradually lost and a concomitant increase in responsiveness to PGE2 was observed. Subsequently, PGE2 responsiveness was also lost; however, continued response to IPT indicated the presence of a hormone-sensitive adenylate cyclase. A similar pattern of hormone responsiveness was observed when a number of frozen stocks of RCB 2.2 cells were thawed and the cells were again maintained in continuous culture. That this pattern of phenotypic change was not unique to clone RCB 2.2 was verified by assessing the hormone responses in other independently selected clones. Although the precise time sequence for hormone response changes was not constant, in all cases the pattern of hormone response changes was similar: i.e., PTH response was always lost and PGE2 response often first increased and then also was lost, despite the maintenance of response to IPT. These data indicate that clonal hormone-responsive populations can reproducibly give rise to unresponsive populations in an ordered series of phenotypic changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Recessive genetic deregulation abrogates c-myc suppression by interferon and is implicated in oncogenesis.

In a previous study we demonstrated that many hematopoietic tumor cells are resistant to the inhibitory effects that interferon exerts on c-myc mRNA expression without losing other receptor-mediated intracellular responses (M. Einat, D. Resnitzky, and A. Kimchi, Nature [London] 313:597-600). We report here that this partial resistance was overridden in two independent stable somatic cell hybrids prepared by fusion between sensitive and resistant cells. The c-myc mRNA transcribed from the active allele of the resistant parent cell was reduced by interferon within the context of the cell hybrid. It was therefore concluded that changes in the cis-acting sequences of c-myc were not involved in this type of relaxed regulation and that resistance resulted rather from inactivation or loss of postreceptor elements which operate in trans. The growth-stimulating effect that this genetic deregulation might have on cells was tested in experimental systems of cell differentiation in which an autocrine interferon is produced. For that purpose we isolated variant clones of M1 myeloid cells which were partially resistant to alpha and beta interferons and tested their growth behavior during in vitro-induced differentiation. The resistant clones displayed higher proliferative activity on days 2 and 3 of differentiation than did the sensitive clones, which stopped proliferating. The loss of c-myc responses to the self-produced interferon disrupted the normal cessation of growth during differentiation and therefore might lead cells along the pathway of neoplasia.

Burkitt Lymphoma↗
PubMed1987

Impact of workshop on students' and physicians' rejecting behaviors in patient interviews.

The "dehumanization" process is often documented among medical students during their clinical clerkship and among physicians. This dehumanization is characterized by an increase in rejecting behaviors (manifested by sarcasm, verbal rejection, contempt, evading eye contact, and ignoring patients' verbal or nonverbal cues) and a decrease in supporting, empathic behaviors. In the study reported here, the authors observed rejecting behaviors during medical interviews and determined that participation in a workshop on supporting behaviors in the medical interview resulted in long-term decrease or abolishment of rejecting behaviors among medical students and physicians.

Attitude of Health Personnel↗
PubMed1987

Extinction of expression of immunoglobulin genes in myeloma X fibroblast somatic cell hybrids.

Adherent hybrids between immunoglobulin-producing mouse myeloma cells and fibroblasts do not produce immunoglobulin polypeptide chains. These hybrids retained the actively rearranged immunoglobulin genes of the myeloma parental cells but lacked immunoglobulin heavy- and light-chain RNA transcripts. We conclude that the shutoff of immunoglobulin production in these hybrids occurs at the transcription or early processing level.

Animals↗
PubMed1987

Effect of plasmacytoma cells on the production of granulocyte-macrophage colony-stimulating activity (GM-CSA) in the spleen of tumor-bearing mice.

Mice bearing syngeneic plasma cell tumors are characterized by elevated numbers of granulocyte-macrophage progenitors (GM-CFU) in the spleen. We investigated the role of syngeneic plasmacytomas in the hematologic response to tumor cell transplantation by assaying the production of granulocyte-macrophage colony-stimulating activity (GM-CSA) by cultured spleen cells of tumor-bearing mice and by plasmacytoma cells, alone and in coculture with spleen cells. Elevated levels of GM-CSA were detected in 7-day culture supernatants of spleen cells from Balb/c mice transplanted 2 weeks previously with syngeneic 4T00.1 plasmacytoma cells. Colony assays of spleen cells from tumor-bearing mice demonstrated the presence of both granulocyte-macrophage and tumor cell colonies. A high frequency of GM-CFU was detected in cultures which had not been supplemented with an exogenous source of GM-CSA. Significant levels of GM-CSA were detected in media conditioned by 4T00.1 plasmacytoma cells. 4T00.1-conditioned medium did not stimulate the growth of primative erythroid (BFU-E) and multilineage (CFU-GEMM) colonies, but stimulated the growth of FDC-P1 cells, thereby establishing the activity produced by 4T00.1 cells as GM-CSF. The levels of GM-CSA in media conditioned by coculturing control spleen and 4T00.1 cells were significantly higher than those detected in media conditioned by spleen cells alone. The colony frequency induced by the coculture supernatants, however, did not exceed the sum of the colonies detected in marrow cell cultures stimulated with media conditioned by control spleen and 4T00.1 cells alone. Our findings demonstrate that murine plasmacytoma cells are capable of secreting GM-CSF. They further suggest a key role for GM-CSA production by tumor cells in the hemopoietic response of mice bearing syngeneic plasma cell tumors.

Animals↗
PubMed1985

Cloning of plasmacytoma micrometastases from spleen.

Soft agarose cloning of tumor cells in spleens from mice bearing 4T00.1 plasmacytomas reveals the ubiquitous presence of micrometastases. The latter can be found in spleens of mice splenectomized as early as 4 h post subcutaneous inoculation of 4T00.1 tumor cells. The total number of potentially proliferating 4T00.1 cells in the spleen is low (approximately 100) and constant for the first 18 days, after which the number increases and reaches 7000 at 27 days post inoculation, when the tumor is greater than 20 mm in diameter. The soft agarose cloning technique detects small numbers of micrometastases in spleen, which cannot be detected by other methods.

Animals↗
PubMed1985

Subclone heterogeneity in a clonally-derived osteoblast-like cell line.

To analyze the phenotypic diversity of a clonal rat osteosarcoma cell line (ROS 17/2) we have subcloned the cell line and characterized four subclones, ROS 17/2-A.II, A.III, A.V, and A.XIV. The subclones retained many of the characteristics of the parent clone that are considered typical of normal osteoblast-like cells; they responded to parathyroid hormone and isoproterenol, and had a negligible response to prostaglandin E2 as measured by their respective changes in cyclic AMP concentration. In addition up to a 75% decrease in 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) binding was observed over a four-fold increase in cell density. The morphologies of the subclones varied from spindle-shaped, fibroblast-like to cuboidal. Doubling times varied from 24 to 48 hours, and basal alkaline phosphatase (AP) levels differed by as much as 10 times over the initial 3 months in culture. After 6 months (approximately 100 PDL), the population doubling time of subclone A.XIV decreased from approximately 48 to approximately 20 hrs and there was a 2.5 to 3-fold increase in saturation density. This cell line was designated A.XIV.1 and was compared to a thawed sample from frozen stock of the original A.XIV isolate, designated A.XIV.2. These two populations, the parent cell line (ROS 17/2) and subclone A.V had similar growth properties, but differed with respect to changes in their alkaline phosphatase activity (AP) with time in culture: that is, all clones increased AP with time but there was a three to five-fold difference in their respective AP levels at various times in culture. All clones except A.V exhibited decreased AP activity upon reaching their saturation densities.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1984

An evaluation of the short-term effects of an interpersonal skills course.

A course on interpersonal skills (IPS) has been introduced as part of the clerkship in internal medicine. The course is given in small groups (8-10 students) with two tutors attached to each group. The use of trigger films in the IPS course has been described previously (Alroy & Ber, 1982). An evaluation of the short-term (2-month) effects of the method is now reported.

Clinical Clerkship↗
PubMed1984

Fusion of plasmacytoma and host cells in vivo: selection of proliferating and nonproliferating cultures.

The double-mutant cell line 4T00.1 is derived from a plasmacytoma of a BALB/c mouse and is resistant to 6-thioguanine and ouabain. These cells were inoculated into (BALB/c X C57BL)F1 mice by different routes--sc, ip, intrasplenically, and intrathymically. The degree of tumorigenicity and pattern of tumor development were site-dependent. Intrasplenic inoculation of 10(3)-10(4) 4T00.1 cells resulted in development of large omental tumors accompanied by marked ascites. Tenfold to a thousandfold more 4T00.1 cells were required to obtain tumors by other routes. From all solid tumors and ascites and from various organs of tumor-bearing mice, which were explanted into culture in double selective medium containing hypoxanthine, aminopterin, and thymidine plus ouabain (in which only hybrids between 4T00.1 and normal cells can survive), proliferating and nonproliferating cultures were obtained. Of the 14 proliferating cultures, 9 proved to be hybrids by chromosome and H-2 isoantigen analyses and were tumorigenic when 10(6) cells were inoculated sc into syngeneic F1 mice.

Animals↗
PubMed1983

Improved efficiency of hybridoma ascites production by intrasplenic inoculation in mice.

Intrasplenic inoculation of small numbers (10(4)) of antibody-producing hybridoma cells into unprimed BALB/c mice resulted in high-titered ascites. By intrasplenic injection, the low number of cells needed to produce ascites was 2-3 logs fewer than that required by ip inoculation. Hybridoma cells suspended in the ascitic fluid could be reestablished in vitro. Furthermore, cells obtained directly from individual, cloned colonies or from previously frozen samples also resulted in high-titered ascites, if the cells were inoculated intrasplenically. This method reduces time and expense required to grow large numbers of hybridoma cells for ip-derived ascites production and allows ready recovery of frequently unstable frozen-thawed cells.

Animals↗