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Biomedical subjects

G Just

Publications and source records attributed to G Just.

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

Faculty practice: nurse educators' views and proposed models.

Faculty practice is an issue that has been extensively debated, yet no consensus about its definition, purposes, or implementation has yet been achieved among nurse educators. This nationwide survey of a random sample of 909 AD and BSN educators was designed to elicit concepts of faculty practice and to find how and why faculty are implementing practice. Sixty percent of the sample are practicing nursing; the reason most frequently given was to maintain clinical skills. The 40% not practicing stated lack of time as the primary reason. Responses demonstrated no differences between AD and BSN educators regarding definition, implementation, and motivation for faculty practice. As a result of the survey, a definition of faculty practice has been formulated and conceptual models of faculty practice delineated. The models that have been developed are the Nurse-Researcher Model, Nurse-Clinician Model, and Nurse-Consultant Model.

Humans↗
PubMed1988

[Visceral leishmaniasis (kala-azar) in acquired immunodeficiency syndrome (AIDS)].

A 32-year-old homosexual with AIDS, who until 1985 was a frequent traveller to South America and mediterranean countries, had recurrent bouts of fever, splenomegaly, arthralgias as well as granulocytopenia and anaemia. Liver and bone-marrow punctures were performed to exclude malignant lymphoma and (or) a mycobacterial infection. Both biopsies revealed Leishmania donovani. During administration of sodium stibogluconate (Pentostam) the fever disappeared for a time and there was clinical improvement, but further treatment was limited because of thrombocytopenia. In patients with AIDS who have splenomegaly with nonspecific fever, visceral leishmaniasis must be considered in the differential diagnosis even outside of endemic regions.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Synthesis of diadenosine 5',5'''-P1,P4-tetraphosphate (AppppA) from adenosine 5'-phosphosulfate and adenosine 5'-triphosphate catalyzed by yeast AppppA phosphorylase.

A novel way of enzymatic synthesis of diadenosine 5',5"'-P1,P4-tetraphosphate (AppppA), which does not involve aminoacyl-tRNA synthetases, has been discovered. Yeast AppppA alpha, beta-phosphorylase catalyzes irreversible conversion of adenosine 5'-phosphosulfate (APS) and ATP into AppppA according to the equation APS + ATP----AppppA + sulfate. In this reaction, the enzyme exhibits a broad pH optimum (between 6 and 8) and requires Mn2+, Mg2+, or Ca2+ ions for activity, with Mn2+ being twice as effective as Mg2+ or Ca2+ at optimal concentration (0.5 mM). The Km values computed for APS and ATP are 80 microM and 700 microM, respectively. The rate constant for the AppppA synthesis is 3 s-1 (pH 8.0, 30 degrees C, 0.5 mM MgCl2). Some ATP analogues like ppppA, GTP, adenosine 5'-(alpha, beta-methylenetriphosphate), and adenosine 5'-(beta, gamma-methylenetriphosphate), but not dATP, UTP, or CTP, are also substrates for AppppA phosphorylase and accept adenylate from APS with the formation of AppppA, AppppG, Appp(CH2)pA, and App(CH2)ppA, respectively. Functional versatility of yeast AppppA phosphorylase may provide a link between metabolism of AppppA on one hand and metabolism of APS and phosphate on the other and raises the possibility of participation of AppppA in regulation of metabolism of APS and/or inorganic phosphate in yeast.

Adenine Nucleotides↗
PubMed1987

The binding of adenosine(5')tetraphospho(5')adenosine to calf thymus histones measured by non-equilibrium dialysis.

Binding of adenosine(5')tetraphospho(5')adenosine (Ap4A) to histones of calf thymus was investigated by non-equilibrium dialysis. Histone H1 interacts with the dinucleotide via two strong sites and competes with Mg2+ ions. Intrinsic dissociation constants were 1.6 +/- 0.1 microM and 11 +/- 1 microM for zero and 0.4 mm-Mg2+ concentration respectively. Binding of poly(dT) and of other nucleotides to histone H1 was measured in an [3H]Ap4A-competition assay. The tendency to form complexes among nucleotides was highest for bisnucleoside tetraphosphates and decreased in the order poly(dT) greater than or equal to Ap4A approximately Gp4G greater than Ap4 much greater than Ap3A approximately Ap5A greater than or equal to ATP, GTP and dTTP. The co-ordination complex derived from Ap4A and cis-diammine-dichloroplatinum(II) was not reactive. The other histones of calf thymus also bound Ap4A with affinities decreasing in the order H4 approximately H3 greater than H1 greater than H2b greater than H2a. Ap4A stimulated the exchange of histone H1 between nucleosomes, but this effect was referred to ionic strength. It did not bind to assembled nucleosomes. Binding of Ap4A to histone H1 was decreased by salt (NaCl). At physiological saline concentration the value of the dissociation constant is commensurable with the value of the Ap4A concentration in the nucleus and thus indicative of complex-formation in vivo.

Adenine Nucleotides↗
PubMed1987

[Cryptosporidium infections in AIDS].

Investigations for cryptosporidia were carried out on 250 fecal samples from 131 HIV-positive patients between December 1985 and July 1986 with kinyoun carbolfuchsin staining. Cryptosporidial oocysts could be detected in six homosexual men. All of the cryptosporidia excretors had symptoms of enteritis. The clinical course and the prognosis depended on the immunological resistance of the host. Five patients with pronounced immune defect had therapy-resistant chronic diarrhea. In one patient with a slight immune defect, the cryptosporidial infection cured spontaneously. A spacial separation of cryptosporidia excretors and patients with weakened resistance is to be considered in view of the possible severe progress form with low tendency to cure and the still lacking specific chemotherapy.

Acquired Immunodeficiency Syndrome↗
PubMed1986

In vitro competition between adenosine(5')tetraphospho(5')adenosine and deoxyribonucleic acid in the reaction with diamminedichloroplatinum(II).

Competition between adenosine(5')tetraphospho(5')adenosine (Ap4A) and DNA for the synthesis of adducts with the cis or trans isomer of diamminedichloroplatinum(II) was measured in the presence and absence of magnesium and spermidinium ions. Reaction products were analysed by circular dichroism, poly(ethyleneimine) thin-layer chromatography and reversed-phase chromatography. Competition was affected by the oligovalent cations that bound specifically to the dinucleotide. Platination of DNA was favoured under all conditions. Chromatin was less competitive. The mechanism was kinetic competition, DNA reacting considerably faster than Ap4A. Platinum(II) did not exchange between adducts and free DNA and Ap4A, respectively. On that basis only low amounts of Ap4A adducts were estimated to be formed under conditions of clinical chemotherapy. The cis and trans isomers of diamminedichloroplatinum(II) were equally effective. Platinum(II) adducts of Ap4A were neither degraded by Ap4A-specific pyrophosphohydrolases nor by phosphodiesterase nor in the presence of unfractionated extract of calf thymus. Unphysiologically high concentrations of Crotalus durissus phosphodiesterase I were required for hydrolytic splitting, the amount of which was similar for both platinum(II) isomer adducts. The results suggest that Ap4A platinum(II) adducts might accumulate during chemotherapy of cancer treatment.

Adenine Nucleotides↗