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Biomedical subjects

J Resnick

Publications and source records attributed to J Resnick.

At least 37 records · Page 2Linked to original sources
PubMed1983

Interaction of single-strand binding protein and RecA protein at the single-stranded DNA site.

Escherichia coli single-strand binding protein (SSB), which participates in DNA replication, also plays a role in DNA repair and induction of SOS functions. We show that the formation of RecA-dATP-single-stranded DNA complexes is influenced by the presence of SSB. In equilibrium reactions with limiting bacteriophage fd DNA, the mutant SSB113 protein competes more effectively than SSB with RecA protein for sites on the DNA. This result can account for the inability of strain ssb113 to amplify RecA protein synthesis and induce lambda prophage. SSB fails to displace RecA protein completely, even at very high concentrations. Both proteins inhibit the dATPase activity of RecA protein in spite of a large proportion of RecA protein still complexed to single-stranded DNA. Analysis of the multiple RecA protein activities and how they respond to the presence of SSB suggests that they fall into two distinct classes. Those that are enhanced by SSB (proteolysis and strand assimilation) and those inhibited by SSB (NTPase, reannealing of complementary single-stranded DNA). We propose a two-state model of conformational change of RecA protein, affected by the number of available free bases in single-stranded DNA relative to the number of RecA monomers, that would explain the choice of mutually exclusive catalytic activities.

Bacterial Proteins↗
PubMed1983

Intravenous treatment of hypokalemic periodic paralysis.

Acute attacks of weakness in patients with hypokalemic periodic paralysis can usually be treated with oral potassium preparations. Occasional patients, however, require intravenous (IV) potassium administration. We studied a patient with hypokalemic periodic paralysis to determine the effect of using 5% glucose as a diluent for potassium administration during acute attacks of weakness. Administration of IV potassium chloride in 5% glucose (50 mEq/L) was associated with a worsening of strength and no rise in potassium level. Intravenous potassium in 5% mannitol was associated with a rise in potassium and improvement in strength. This study confirms the hazard of using glucose-containing solutions for correction of hypokalemia.

Adult↗
PubMed1982

Cobalt: an effector of E. coli recA protein activity.

Studies of cation requirements in the recA-catalyzed proteolysis of lambda repressor and strand assimilation reactions have demonstrated that Co2+ significantly enhances both activities. In the presence of 4mM MgCl2, the optimal concentration of CoCl2 for proteolysis was 1mM. 2mM Co2+ increased the rate and extent of D-loop formation as measured by membrane filtration. Cobalt did not replace Mg2+ for the ssDNA-dependent ATPase activity of recA, and did not affect the rate of hydrolysis of ATP, measured over a wide range of DNA concentrations. Cobalt did prevent the Mg-dependent ssDNA renaturation catalyzed by recA protein. Membrane filter binding assays established that Co2+ increases the affinity of recA protein for ssDNA with ATP, dATP, or ATP gamma S as cofactors. The dissociation of recA protein from ssDNA-nucleoside triphosphate complex was much slower with CoCl2. This metal provides an excellent tool for dissecting the various activities inherent in recA protein.

Adenosine Triphosphatases↗
PubMed1982

Escherichia coli single-strand DNA binding protein from wild type and lexC113 mutant affects in vitro proteolytic cleavage of phage lambda repressor.

In Escherichia coli, the single-strand DNA-binding protein (SSB) is required for DNA replication. A mutation of the ssb gene, lexC113, imparts to the cells UV sensitivity and inability to induce lambda prophage and to amplify recA protein, indicating participation of SSB in DNA repair and viral induction processes. We report the effect of purified SSB, isolated from wild-type and lexC113 strains, on the recA-mediated proteolysis of lambda repressor in vitro. (i) These proteins abolished the inhibition produced by excess single-strand DNA and (ii) in the presence of the binding proteins, the apparent stoichiometry--1 monomer of recA to 6 nucleotides of single-strand DNA [Craig, N. L. & Roberts, J. W. (1980) Nature (London) 283, 26-30] was no longer observed. (iii) At the optimal concentration--1 protein monomer to 8 nucleotides--they increased the rate and extent of repressor cleavage at all single-strand DNA concentrations, including that observed at the apparent optimal DNA concentration. (iv) At binding protein/nucleotide ratios greater than or equal to 1:3, SSB from lexC113 inhibited repressor cleavage while that from wild type did not. (v) These results are consistent with the notion that SSB is probably involved in the induction of prophages in vivo.

Bacterial Proteins↗
PubMed1980

Induction of prophage lambda without amplification of recA protein.

The requirement for amplified synthesis of recA protein in the UV-promoted induction of coliphage lambda was studied. We confirmed that a low concentration of rifampicin inhibited specifically the increased synthesis of recA protein after an inducing treatment (Satta and Pardee, 1978). Under these conditions, using an optimal dose of UV, E. coli lysogens were induced, producing active phage. The drug delayed the onset of induction and with increasing concentrations affected the yield of phage, but all the cells lysed. The results established that induction can proceed without amplification of recA protein synthesis.

Bacteriophage lambda↗
PubMed1978

Interaction of bacteriophage lambda repressor with nonoperator DNA containing single-strand gaps.

In direct binding assays, purified lambdaind+ repressor displayed high affinity for nonoperator DNA containing single-strand gaps. Its affinity for this same DNA but completely double-stranded, nicked, or denatured was considerably lower. In contrast, purified lambdaind- repressor had 1/10th the affinity for the gapped DNA, a level comparable to that of purified lac repressor. In the presence of limiting amounts of ind+ repressor, nonoperator DNA containing gaps could be shown to compete effectively with lambda DNA for binding of repressor. A previous model of lambda induction [Sussman, R. & Ben-Zeev, H. (1975) Proc. Natl. Acad. Sci. USA 72, 1973--1976], based on the assumption that this phenomenon involves the binding of repressor to lesions in the host DNA, is reevaluated in the light of the data reported here.

Binding Sites↗
PubMed1978

Renal transplantation in a patient with lipoatrophic diabetes. A case report.

A patient with congenital generalized lipodystrophy developed nephrotic syndrome with progressive renal glomerulosclerosis attributed to diabetic nephropathy. Renal transplantation was performed and the patient was discharged with normal renal function. Marked hyperlipidemia (17,500 mg/dl) persisted. One month later renal malfunction developed, and an open renal biopsy was performed when there was no response to antirejection therapy. Massive lipid deposition in renal tubular cells with tubular necrosis and hemorrhage was present but only minimal evidence of graft rejection. Rejection therapy was tapered and renal function stabilized. Death occurred 2 months later because of pulmonary sepsis. Patients with generalized lipodystrophy and severe hyperlipidemia may be at an unusually high risk for renal homograft destruction.

Adult↗
PubMed1973

The association of respiratory infection, recurrent hematuria, and focal glomerulonephritis with activation of the complement system in the cold.

The study of the activation of C3, C5, and C7 associated with the conversion of C3 in the serum of a 9-yr old girl after incubation at 0 degrees C for 6-8 h without utilization of C1, C4, and C2 is described. The patient has upper respiratory infections associated with recurrent gross hematuria, focal glomerulonephritis, and transient renal insufficiency. Histological lesions demonstrated the presence of B1c globulin IgA and properdin in the glomeruli. The activation of complement (C) in the cold requires the patient's IgA. Removal of IgA from the serum by immunoadsorption prevents activation and conversion of C3. Bactericidal and phagocytic activity is also impaired after incubation. C3 proactivator (C3PA) level is reduced before and after incubation. Properdin level drops after incubation. These findings suggest that the activation of C3 which is demonstrable in vitro may be a continuous process in vivo.

Child↗
PubMedDate not supplied

A pilot study of the prevalence of herpes genitalis among selected groups of patients seeking care in a family practice center.

Herpes genitalis is typically studied in patient panels identified at specialized sexually transmitted disease clinics or with information obtained from herpes self-help groups. This article reports the results of a descriptive pilot study of the prevalence of herpes genitalis in family practice. The feasibility of obtaining psychosexual information on sexually transmitted diseases from more than 600 patients from five family practice practices was assessed. These initial data show that in the family practices participating in this study: 1) genital herpes is a low prevalence disease; 2) psychosocial adjustment to the disease among infected persons is usually reported as good, apart from sexual effects; and 3) close to 30% of the study population reported having prior sexually transmitted diseases. Problems involved in generalizing the results of this research and the limitations of conducting collaborative clinical research in family practice settings are reviewed.

Activities of Daily Living↗