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Biomedical subjects

J Krupinski

Publications and source records attributed to J Krupinski.

At least 55 records · Page 3Linked to original sources
PubMed1993

A monoclonal antibody detects heterogeneity in vascular endothelium of tumours and normal tissues.

A new murine monoclonal antibody (MAb), E-9, has been raised using tissue-cultured human umbilical vein endothelial cells. The antigen recognized by this MAb is a peptide of 170 kDa under non-reducing conditions and 96 kDa under reducing conditions. MAb E-9 showed marked heterogeneity in its distribution in various tissues. The antigen recognized by it was present in vascular endothelial cells of all tumours, foetal organs and in regenerating and inflamed tissues. It stained a few normal tissues. However, with the exception of tonsils, staining tended to be weak and limited to a few blood vessels, as revealed by double staining using pan-endothelial antibody (CD31) and antibody to von Willebrand factor, another marker of vascular endothelium. Surprisingly, blood vessels within the placental villi were completely negative. The function of the antigen recognized by MAb E-9 is not known, but its evaluation and use should increase our understanding of angiogenesis.

Adult↗
PubMed1992

Molecular diversity in the adenylylcyclase family. Evidence for eight forms of the enzyme and cloning of type VI.

The conservation of amino acid sequence among types I-IV adenylylcyclase has made it possible to apply the polymerase chain reaction to examine the extent of the molecular diversity within this family of enzymes. cDNA templates from rat heart, liver, kidney, guinea pig brain and testes, and mouse skeletal muscle were amplified with primers specific to adenylylcyclase sequences. Evidence was obtained for a total of eight distinct gene products divisible into five subfamilies. Five of the products correspond to regions from cloned forms of adenylylcyclase, while three are previously unidentified. As many as seven different adenylylcyclases are expressed in rat heart, liver, and kidney based on this analysis. Two newly identified polymerase chain reaction (PCR) products were utilized to screen a rat cDNA library from H35 Reuber hepatoma cells. A 6080-nucleotide cDNA contains an open reading frame encoding the 1166-amino acid type VI protein which has a predicted topography similar to that of other adenylylcyclases. The type VI message is abundantly expressed in rat heart, kidney, and brain. Human embryonal kidney cells stably expressing the cDNA showed an enhanced response to isoproterenol that could be inhibited by carbachol in intact cells. Increases in intracellular Ca2+ contribute to the inhibitory effect of carbachol.

Adenylyl Cyclases↗
PubMed1992

Social psychiatry and sociology of mental health: a view on their past and future relevance.

The origins of social psychiatry can be traced to the age of enlightenment and to the effects of the industrial revolution. Social psychiatry deals with social factors associated with psychiatric morbidity, social effects of mental illness, psycho-social disorders and social approaches to psychiatric care. Since the end of World War II up to the early seventies it has been claimed that social psychiatry should concentrate on the fight against war, poverty, racial discrimination, urban decay and all other social ills affecting people's mental health, and that the psychiatrist should be responsible for the mental health of the society. In contrast, sociology of mental health questioned the expertise of the psychiatrist and the very existence of mental illness, claiming that it covers deviant behaviour rejected by the society. The paper refutes this approach indicating that not the existence but the perception and presentation of psychiatric illness are socially determined. Acknowledging the contribution of sociology and social sciences to psychiatry, it is suggested that the heroic period of social psychiatry and the iconoclastic approach of sociology of mental health are over. However, social psychiatry, enriched by the use of epidemiological methods, has still much to offer to the daily practice of psychiatry.

Community Mental Health Services↗
PubMed1991

Molecular cloning and characterization of a Ca2+/calmodulin-insensitive adenylyl cyclase from rat brain.

Biochemical, immunological, and molecular cloning studies have suggested the existence of multiple forms of adenylyl cyclase (EC 4.6.1.1). An adenylyl cyclase cDNA clone (type II) was isolated from a rat brain library and found to encode a protein of 1090 amino acids that was homologous to but distinct from the previously described Ca2+/calmodulin-stimulated adenylyl cyclase from bovine brain. Expression of the type II cDNA in an insect cell line resulted in an increased level of adenylyl cyclase activity that was insensitive to Ca2+/calmodulin. Addition of activated Gs alpha protein to type II-containing membranes increased enzyme activity. The mRNA encoding the type II protein was expressed at high levels in brain tissue and at low levels in olfactory epithelium and lung. The existence of multiple adenylyl cyclase enzymes may provide for complex and distinct modes of biochemical regulation of cAMP levels in the brain.

Adenylyl Cyclases↗
PubMed1991

Expression and characterization of calmodulin-activated (type I) adenylylcyclase.

A complementary DNA that encodes a bovine brain, calmodulin-sensitive (type I) adenylylcyclase has been inserted into the baculovirus genome under the control of the strong polyhedron promoter. Expression of the recombinant adenylylcyclase in Sf9 cells using recombinant baculovirus increases adenylylcyclase activity in cell membranes to 10-20 nmol.min-1.mg-1 (approximately 0.1% of membrane protein). The catalytic activity of the recombinant adenylylcyclase can be stimulated by Gs alpha, calmodulin, or forskolin, and it can be inhibited by adenosine analogs and by G protein beta gamma subunit. The specific activity of the purified recombinant protein approximates 5 mumol.min-1.mg-1. This is similar to that of the enzyme purified from bovine brain. Type I adenylylcyclase has a quasiduplicated structure. There are two membrane-spanning domains, each with six putative transmembrane helices, and there are two presumed nucleotide-binding domains that are about 55% similar to each other. No catalytic activity is detectable when each half of the adenylylcyclase molecule is expressed by itself. However, coexpression of the two halves results in considerable enzymatic activity. Interaction between the two halves of adenylylcyclase may be necessary for catalysis.

Adenylyl Cyclase Inhibitors↗
PubMed1989

Adenylyl cyclase amino acid sequence: possible channel- or transporter-like structure.

Complementary DNA's that encode an adenylyl cyclase were isolated from a bovine brain library. Most of the deduced amino acid sequence of 1134 residues is divisible into two alternating sets of hydrophobic and hydrophilic domains. Each of the two large hydrophobic domains appears to contain six transmembrane spans. Each of the two large hydrophilic domains contains a sequence that is homologous to a single cytoplasmic domain of several guanylyl cyclases; these sequences may represent nucleotide binding sites. An unexpected topographical resemblance between adenylyl cyclase and various plasma membrane channels and transporters was observed. This structural complexity suggests possible, unappreciated functions for this important enzyme.

Adenylyl Cyclases↗
PubMed1988

Insulin-dependent phosphorylation of GTP-binding proteins in phospholipid vesicles.

The involvement of GTP-binding proteins (G proteins) in insulin action has been investigated in an in vitro system. Insulin receptors that have been purified by wheat germ lectin chromatography and either tyrosine-agarose chromatography, sucrose density centrifugation, or insulin-Sepharose chromatography have been co-inserted into phospholipid vesicles with different purified G proteins. The results of these studies indicate that a specific insulin-promoted phosphorylation of two G proteins, Go and Gi, can occur in these phospholipid vesicles. Bovine retinal transducin is a poor substitute for Go and Gi, being only weakly phosphorylated by the insulin receptor, and bovine brain Gs is not a substrate. The phosphorylation of Gi and Go occurs primarily on the alpha-subunits. Under optimal conditions, about one alpha o- or alpha i-subunit is phosphorylated on a tyrosine residue for every two beta-subunits of the insulin receptor, suggesting a 1:1 interaction between these G proteins and the heterotetrameric (alpha 2 beta 2) insulin receptor molecular. The inactive (GDP-bound) form of the alpha-subunits appears to be the preferred substrate, with the phosphorylation being significantly reduced in alpha o and alpha i upon the binding of guanosine 5'-O-thiotriphosphate (GTP gamma S) and completely eliminated in the pure alpha-GTP gamma S complex of transducin. The Gi and Go proteins also cause an enhancement of the insulin-stimulated receptor autophosphorylation. This enhancement is a reflection of an increased incorporation of the insulin receptor into lipid vesicles which is induced by these G proteins. Taken together these results provide evidence for the interactions of G proteins with the insulin receptor in a lipid milieu.

Animals↗
PubMed1986

Steady-state ATP synthesis by bacteriorhodopsin and chloroplast coupling factor co-reconstituted into asolectin vesicles.

A method was developed for the co-reconstitution of bacteriorhodopsin and chloroplast coupling factor in asolectin vesicles. First, bacteriorhodopsin was reconstituted from a mixture of octyl glucoside, asolectin, and protein in the presence of ethylenediaminetetraacetic acid by passage through a Sephadex G-50 centrifuge column. Then, the purified coupling factor was reconstituted from a mixture of sodium cholate, bacteriorhodopsin vesicles, and coupling factor in the presence of Mg2+ by passage through the centrifuge column. Sucrose density-gradient centrifugation indicated a band of vesicles with slightly different positions in the gradient for maximum vesicle concentration, bacteriorhodopsin vesicle concentration, ATP synthesis, and ATP hydrolysis. The rate of light-driven ATP synthesis reaches a limiting value as the concentration of bacteriorhodopsin and the light intensity are increased. A steady-state rate of ATP synthesis of 1 mumol per mg of coupling factor X min-1 has been achieved. Apparently this rate is limited by the heterogeneity within the vesicle population and by the ability of bacteriorhodopsin to form a sufficiently large pH gradient.

Adenosine Triphosphatases↗
PubMed1985

Phase-lifetime spectrophotometry of deoxycholate-purified bacteriorhodopsin reconstituted into asolectin vesicles.

A rapid reconstitution procedure has been developed to insert deoxycholate-purified bacteriorhodopsin (bR) into asolectin vesicles. The procedure relies on the ability of the hydrophobic resin Bio-Beads SM-2 to remove octyl glucoside from a mixture of deoxycholate-purified bR, asolectin, and the detergent. Light-dependent acidification of the vesicle interior is observed with the reconstituted preparations as judged by the fluorescence quenching of an entrapped pH indicator, pyranine. Inhibition of proton pumping by the addition of LaCl3 to the external medium indicates that approximately 90% of the bR is oriented such that it pumps protons into the vesicles. Phase-lifetime spectrophotometry was used to study the relaxation processes associated with the intermediate in the photocycle of the reconstituted bR which absorbs at 410 nm. Amplitude spectra indicate that these absorbance changes are associated with the M intermediate in the bR photocycle. Two relaxation processes are observed. One is characterized by a relaxation time of approximately 4 ms and is independent of pH over the range 4.4-9.4. The longer relaxation time varies from 4 to 200 ms in the same pH range. By digitization of transients, which are observable when the actinic source is modulated at a low frequency, information about the dependence of the slower process on the light intensity and carbonyl cyanide m-chlorophenylhydrazone was obtained. The results can be interpreted in terms of two different forms of the M intermediate that decay on parallel kinetic paths. To explain the pH dependence of the decay rate, the slower decaying form must have three coupled protonation states, each with a different decay rate.

Bacteriorhodopsins↗
PubMed1984

Changing patterns of migration to Australia and their influence on the health of migrants.

Whilst before World War II migration to Australia was almost entirely from the British Isles, over 60% of post-War II migrants came from other countries other than Britain. They arrived in Australia in distinct waves: Eastern European refugees were followed by migrants from Western Europe, who were later replaced by migrants from the Mediterranean Basin and finally by Asians, initially from the Indian subcontinent, afterwards from Lebanon and most recently from Indo-China. These patterns of migration were changing the numerical size, age distribution and length of residence in Australia of the different ethnic groups. The paper describes the influence of these changes on physical and mental health of the migrants. Physical morbidity was related to 'imported diseases', to the different physical and social environment and to differences and changes in eating and other habits. Psychiatric disorders were associated with traumatic experiences encountered prior to migration, and with stresses of migration and adjustment to the new country. Thus, in evaluating the health of immigrants, one has to take into account the sources from which the migrants were drawn, their situation in the host society, their numerical growth and age distribution, as well as acculturation to the country settlement.

Adolescent↗
PubMed1984

Multidisciplinary or nondisciplinary: evaluation of staff functioning in a community mental health centre.

This paper describes the staffing aspects of an experimental community mental health centre (Melville Clinic). The different components of staff roles of members of a team consisting of different health professionals, crystallised during the three-year period with a shift from a 'nondisciplinary' to a 'multidisciplinary' approach, with preservation of 'generalised' and 'specialised', 'clinical' and 'community' roles of all staff members. The decision-making in the centre oscillated between group decisions by all staff members, and the acceptance of the leading role of the psychiatrist with the active multidisciplinary teamwork in community mental health centres.

Community Mental Health Centers↗
PubMed1984

Feasibility of discharge of chronic psychiatric patients.

In a survey of all (2795) chronic psychiatric patients resident in Victorian Mental Health Division hospitals, charge nurses were asked to assess patients' levels of physical and psychological dependence on nursing care, aggressive and difficult behaviour and their preferred future placement. The vast majority were 'old' chronic patients and nurses considered the present placement as the most appropriate for two-thirds of the surveyed population. We adopted our own criteria of placement needs, such as level of physical and psychological dependence, behavioural problems and treatment received. Of the 2795 patients, one-quarter (682) would require continuing hospital care. The remainder could be transferred, depending on their characteristics, to intensive or general nursing care homes, hostels or special accommodation houses, provided that such facilities are available and the participation of patients in various therapeutic activities was ensured.

Adult↗
PubMed1983

Phase-lifetime spectrophotometry of membranes from ion flux mutants of Halobacterium halobium.

Phase-lifetime spectrophotometry has been used to study the rate processes associated with intermediates in the photocycling pigments in membrane vesicles of mutant strains of Halobacterium halobium. Vesicles deficient in bacteriorhodopsin, but containing halorhodopsin, were monitored with light at 490 nm. Two relaxation processes, with kinetic parameters largely independent of pH over the range 6.2-7.8, were found to be associated with halorhodopsin photocycling in 4 M NaCl, 10 mM buffer at 23 degrees C. The average relaxation times are 0.94 and 11.4 ms. When vesicles deficient in both bacteriorhodopsin and halorhodopsin were monitored at 370 nm, a single relaxation process with an average relaxation time of 168 ms was detected. This process is independent of pH over the range 4.7-8.8. Examination of vesicles from ion flux mutants showed this slow process to be unrelated to halorhodopsin content and to derive from another photoreactive retinal pigment, possibly the recently described slow cycling pigment s-rhodopsin.

Bacteriorhodopsins↗