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Biomedical subjects

H Rubin

Publications and source records attributed to H Rubin.

At least 181 records · Page 10Linked to original sources
PubMed1983

Improving a pharmaceutical purchasing and inventory control system.

A method by which a pharmacy department improved its purchasing and inventory control system is described. System changes to the computerized inventory control system included implementation of a formulary, affiliation with a group purchasing association, and transfer of specified purchasing and inventory control functions to the technical staff of the purchasing department. Pharmacy maintained the decision-making authority over all vendors and dosage forms of drug products. Optimal results were achieved when the purchasing department's pharmacy buyer position was staffed with an employee who had previous experience as a clerical worker in the pharmacy. The authors state that this system has proved to be an effective, cost efficient method of purchasing and inventory control of pharmaceuticals in their hospital.

Computers↗
PubMed1982

Production of antibodies to human factor VIII in the ascitic fluid of C57BL/6J mice.

A method is described for the production of a murine antiserum to human factor VIII, and the quantitation of factor VIII related antigen using this antiserum. C57BL/6J mice were injected intraperitoneally with a mixture of factor VIII and complete Freund's adjuvant. Ascitic fluid developed after repeated innoculations for seven to eight weeks, and was subsequently tapped. Using this antiserum, factor VIII related antigen was quantitated by immunoelectrophoresis and enzyme immunoassay. This method provides a simple and economical way of producing an antiserum to factor VIII, and may also be applicable to other proteins available in submiligram quantities.

Animals↗
PubMed1982

Mg2+-sensitive alterations in Ca2+ regulation associated with cell transformation.

The intracellular Ca2+ content of nontransformed Balb/c3T3 cells is two to three times higher than that of a spontaneously transformed derivative. Depriving either cell type of extracellular Mg2+ causes a 2- to 3-fold increase in their Ca2+ content over a 24-hr period. Restoring Mg2+ to the medium decreases the Ca2+ content of the cells to their original values in about the same time. The increase in Ca2+ content is not blocked by cycloheximide suggesting that normal rates of protein synthesis are not required to produce this effect. Mg2+ deprivation also decreases the initial rate of Ca2+ efflux from the transformed cells and increases the size of the slowly exchanging fraction of Ca2+ to the levels found in the nontransformed cells. Since Mg2+ deprivation normalizes the appearance and growth behavior of the transformed cells, the possible intermediary role of Ca2+ in this normalization was studied. Large changes in extracellular Ca2+ produced large changes in the Ca2+ content of the transformed cells with little change in appearance or thymidine incorporation rate. Ca2+ deprivation did inhibit thymidine incorporation in early passage nontransformed cells; however with repeated passage, this effect decreased, as did the Ca2+ content of these cells. The possible role of Mg2+ in regulating cellular Ca2+ content and distribution is discussed, as is the relation of Ca2+ content and distribution to the development of the transformed state.

Animals↗
PubMed1982

Role of small t antigen in the acute transforming activity of SV40.

A plasmid, pHR402, containing SV40 sequences that include a truncated early region bearing an intact t-coding sequence and a functionally intact late region, was introduced into thymidine kinase deficient (tk-) mouse L cells by cotransformation with a cloned tk gene. tk+ cotransformants synthesized SV40 t but not T antigen, and no truncated T-coding sequence products were detected. The viral sequences of pHR402 were reconstituted as a virus in COS1 cells, and acute infection of untransformed mouse cells with this viral stock (SV402) also led to the appearance of t but not T or a truncated T. Abortive transformation assays of such infected cells were negative, as were those performed on the same cells infected with either of two viral mutants (dl883 and dl884), each of which leads to T but not t synthesis. However, mixed infection with SV402 and either dl883 or dl884 led to a clear abortive and permanent transformation response. Thus, at least in part, t and T appear to function in a complementary fashion in eliciting transformation expression by SV40-infected cells.

Animals↗
PubMed1982

Self-normalization of highly transformed 3T3 cells through maximized contact interaction.

Nontransformed and moderately and highly transformed BALB/c 3T3 cells maintained on small coverslips in a large volume of medium multiplied to 2, 3, and 4 times higher population density, respectively, than they did in conventional cultures. Deprivation of Mg2+ caused highly transformed cells on coverslips to assume the appearance of nontransformed cells, decrease their rate of multiplication, and stop further growth at a much lower saturation density than the same cells in physiological Mg2+. The latter cells reached a saturation density of 10(6)/cm2 and their rate of DNA synthesis decreased progressively with increased crowding. At saturation density, cells in physiological Mg2+ took on an appearance and arrangement similar to normal fibroblasts. They developed a high requirement for serum to initiate DNA synthesis. When transferred at low density, they flattened out on a plastic surface and maintained the appearance of nontransformed cells for approximately 1 day. Onset of DNA synthesis and multiplication in the transferred cells was delayed for periods characteristic of quiescent nontransformed cells stimulated by fresh medium or transfer. Cells from crowded coverslips were approximately 1/10th as efficient at colony formation when suspended in agar as cells from uncrowded coverslips. They also had a significantly lower Mg2+ content. The crowded cells returned to their transformed morphological and growth behavior 2 to 3 days after transfer at low density. We conclude that a very high degree of crowding causes highly transformed cells to revert to the phenotype of nontransformed cells. Other treatments such as deprivation of Mg2+ or inorganic orthophosphate can achieve similar results. It appears that a balanced reduction in rates of metabolism and multiplication can restore the normal phenotype to transformed cells, implying that they differ only quantitatively from nontransformed cells. The putative role of Mg2+ in the regulation of multiplication and in transformation of animal cells is discussed.

Animals↗
PubMed1982

Effect of magnesium content on density-dependent regulation of the onset of DNA synthesis in transformed 3T3 cells.

A spontaneously transformed clone of BALB/c 3T3 cells became more transformed after more than 90 passages as indicated by increased rounding of cells, multiplication to a higher saturation density, and increased ability to form colonies when suspended in agar. When the extracellular concentration of Mg2+ was sharply reduced, the highly transformed cells flattened, assumed the shape of nontransformed cells, and became regularly arranged in cohesive arrays. If crowded when deprived of Mg2+, they lost more intracellular Mg2+ than did nontransformed and early passage-transformed cells and remained at constant cell density for at least 10 days. The intracellular content of neither Na+ nor K+ changed consistently with Mg2+ deprivation, but the Ca2+ content increased more than 2-fold. The sensitivity of the onset of DNA synthesis to inhibition by Mg2+ deprivation increased with the extent of crowding of the cultures. This was demonstrated by varying population density within a single culture dish as well as from culture to culture. The loss of intracellular Mg2+ in low concentrations of extracellular Mg2+ increased with cell crowding as did the inhibition of DNA synthesis per fractional loss of intracellular Mg2+. Neither deprivation of K+ or Ca2+ nor addition of cyclic adenosine 3':5'-monophosphate produced a density-dependent inhibiton of DNA synthesis. The results indicate that a reduction of the Mg2+ content of highly transformed cells restores density-dependent inhibition of the onset of DNA synthesis, which is a characteristic property of nontransformed cells. The differences in Mg2+ retentiveness with population density may reflect differences of intracellular distribution and binding of Mg+, which could in turn explain some of the regulatory effects of population density on metabolism and growth.

Animals↗
PubMed1981

Evaluation of Mg2+ as an intracellular regulator of uridine uptake.

The rate of uptake of the nucleoside uridine increases within minutes after adding a growth stimulus to quiescent 3T3 cells. We have previously shown this uptake rate to be highly sensitive to changes in the intracellular concentration of Mg2+. In the present paper, the alteration of uptake by Mg2+ is shown to occur at the phosphorylation step - the same point at which serum acts to modulate uridine uptake. The serum stimulation of uridine uptake can be mimicked by Mg2+ alone or blocked by partially depleting cells of their Mg2+. Work with cell-free extracts shows that the uridine kinase enzyme responds to Mg2+ in a manner similar to that exhibited by whole cells whose concentrations of Mg2+ have been raised. In addition, the enzyme's inhibition by ATP is relieved by raising the Mg2+ concentration. Thymidine uptake, a reaction which does not respond quickly to mitogenic stimulation, is unaffected by alterations in Mg2+ concentration. These results are discussed in terms of a possible role for Mg2+ as an intracellular regulator of uridine uptake and other reactions of the coordinate response of cells to external effectors.

Adenosine Triphosphate↗
PubMed1981

Theophylline magnesium salicylate, a new xanthine compound.

Interaction of 1 mole of magnesium salicylate and 2 moles of theophylline in water precipitated a crystalline compound, identified as theophylline magnesium salicylate pentahydrate from analytical and supportive physicochemical data. Similarly, barium salicylate and theophylline produced theophylline barium salicylate. No precipitates were formed with calcium salicylate or strontium salicylate under the same conditions. Theophylline magnesium salicylate is not a mixture of components and differs in composition from the known theophylline calcium salicylate dihydrate. Unlike the latter compound, it is not alkaline.

Animals↗
PubMed1981

Growth regulation, reverse transformation, and adaptability of 3T3 cells in decreased Mg2+ concentration.

A nontransformed and a spontaneously transformed clone of BALB/c 3T3 cells were compared for their capacity to multiply in decreased concentrations of Mg(2+). Cells of the nontransformed clone were flat, formed regularly patterned, nonoverlapping arrays, required high serum concentration for multiplication, had a low saturation density, and did not make colonies in agar. Cells of the transformed clone were slender and spiky, formed random, overlapping arrays, multiplied in low serum concentrations, and had no fixed saturation density, and 20-30% of them formed colonies in agar. The saturation density of the nontransformed clone was decreased in a growth-limiting supply of Mg(2+) in proportion to the reduction in initial rate of multiplication. At very low Mg(2+) concentrations, saturation occurred when less than half of the surface of the dish was covered with cells. The transformed cells did not reach a stable saturation density in low Mg(2+) concentrations, but their growth rate did slow down when they became crowded, and a transient saturation density was reached at the lowest Mg(2+) concentrations that allowed multiplication. Limiting the supply of Mg(2+) caused the transformed cells to flatten and to assume a regularly patterned, non-overlapping relationship to one another, resembling that of the nontransformed cells. This also occurred in BALB/c 3T3 cells transformed by infection with Moloney mouse sarcoma virus. After 1 week in low concentrations of Mg(2+), the nontransformed cells began to multiply and to incorporate [(3)H]thymidine at a rapid rate. The transformed cells did so also and, in addition, reverted to their transformed appearance. The intracellular content of Mg(2+) was not significantly decreased when the extracellular concentration was decreased to 1/50th. The results suggest that: (a) limited contact among cells already multiplying at a reduced rate is sufficient to halt further multiplication; (b) a very small decrease in intracellular Mg(2+) content or in membrane-associated Mg(2+) causes transformed cells to assume aspects of the appearance and behavior of nontransformed cells (i.e., Mg(2+)-regulated reactions may be involved in determining the transformed phenotype); and (c) cells multiplying at a slow rate in low concentrations of Mg(2+) begin to multiply faster after about 1 week, due either to an adaptation of the cells or to a change in the cellular microenvironment.

Animals↗
PubMed1981

Restoration of normal appearance, growth behavior, and calcium content to transformed 3T3 cells by magnesium deprivation.

A spontaneously transformed clone was isolated from repeatedly passaged BALB/c 3T3 cells. The transformed cells were rounded or slender and elongated, were randomly arranged in an overlapping pattern, grew to high cell density, and had a low requirement for serum. The rates of multiplication and DNA synthesis of the nontransformed and the transformed lines were reduced for several days by drastic reduction in the Mg2+ concentration of the medium, but the rate of DNA synthesis in the Mg2+-deprived cultured increased after 6--8 days, suggesting an adaptation of the cells or a change in local environment. When maintained in very low Mg2+ concentrations the transformed cells assumed the appearance and arrangement of nontransformed cells within 1 day. The rate of DNA synthesis in the transformed cultures in 1.0 mM Mg2+ was independent of serum concentration. After 3 days of Mg2+ deprivation, however, the rate of DNA synthesis became highly dependent on both serum concentration and population density, thus resembling the growth behavior of nontransformed cells. Neither deprivation of K+ or Ca2+ nor addition of dibutyryl cyclic AMP produced these effects. The Mg2+ contents of nontransformed and transformed cells in physiological concentrations of Mg2+ were similar and only slightly reduced by incubation for 4 days in Mg2+-deficient medium. In 1.0 mM Mg2+, the Ca2+ content of the nontransformed cells was approximately 3 times higher than that of the transformed cells. After incubation in Mg2+-deficient medium, the Ca2+ contents of both cells types increased; that of the transformed cells slightly exceeded that of the nontransformed cells in Mg2+-sufficient medium. The results show that Mg2+-deprived transformed cells closely resemble nontransformed cells in appearance, requirement for serum, response to cell population density, and Ca2+ content. They also show that these parameters can be regulated coordinately by Mg2+ and support the suggestion that a defect in regulation by Mg2+ is a basic feature of the malignant transformation.

Animals↗
PubMed1980

Acute calcific quadriceps tendinitis.

Acute calcific quadriceps tendinitis can be the cause of acute periarthritis of the knee. Physical examination can detect cellulitis and a tender tendon sheath. Lateral roentgenograms of soft tissues show thickening of the tendon and sometimes small flecks of amorphous calcification within the body of the tendon near the attachment. Although hyperostosis of the patella near the tendon attachment is often present, it is well defined ossification and not associated with the acute symptoms. The amorphous calcium deposits quickly disappear during the acute tendinitis and are not detected on follow-up radiologic examination.

Acute Disease↗
PubMed1980

Identification and initial characterization of a new low-molecular-weight virus-encoded T antigen in a line of simian virus 40-transformed cells.

SV80 cells, a simian virus 40 (SV40)-transformed derivative of a strain of human fibroblasts, synthesize an 8-kilodalton anti-T reactive polypeptide in addition to large T and small t antigens. Although not observed during lytic infection carried out under a variety of conditions, an anti-T reactive molecule which comigrated with the SV80 8-kilodalton protein during sodium dodecyl sulfate-polyacrylamide gel electrophoresis was synthesized by one of five other SV40-transformed cell lines studied. The SV40 8-kilodalton protein was present in lysates of cells exposed to a brief pulse of radioactive methionine and did not accumulate during an extended chase period. This polypeptide could not by generated by mixing an unlabeled extract of SV80 cells with a labeled extract of infected monkey cells. The 8-kilodalton molecule reacts with antibody raised against homogeneous large T antigen, is present only in the cytoplasm, is not complexed with T, lacks DNA-binding properties, and is not phosphorylated. This protein could be translated in a cell-free system programmed by SV40-specific mRNA. At least two messenger species (approximately 19S and approximately 22S) directed its synthesis. Tryptic peptide analysis of [35S]methionine-labeled proteins demonstrated that the 8-kilodalton protein contains all eight of the common T/t peptides and one additional peptide not present in the maps of t or T. It lacks both of the t-unique peptides. The organization of the integrated viral sequences which encode this molecule was determined by restriction endonuclease analysis. In particular, SV80 cells contain at least two integrated SV40 genomes which are oriented in tandem, with an intervening cellular sequence..

Animals↗