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Biomedical subjects

A Lustig

Publications and source records attributed to A Lustig.

At least 109 records · Page 6Linked to original sources
PubMed1982

Regulation of the nuclear-coded peptides of yeast cytochrome c oxidase.

We have analyzed the catabolite regulation of cytochrome oxidase by assaying changes in the synthesis of precursors of the nuclear-coded peptides (IV--VII) of cytochrome c oxidase in an in vitro reticulocyte cell-free system programmed with RNA isolated from cells grown in either glucose or raffinose. As a first step, we have characterized antibodies which bind to the precursors of subunits V and VI. Initial translation products for subunits IV and VII have also been tentatively identified by utilizing these antibodies. The messenger RNAs coding for the precursors of the nuclear-coded subunits fall in the expected size range of 8--15 S. Catabolite repression of the nuclear-coded oxidase peptides appears to be regulated by the abundance of their messenger RNAs. Translation of messenger RNA isolated from yeast cells grown on glucose indicates a coordinate and uniform increase in precursor synthesis during glucose derepression. In contrast, when RNA isolated from raffinose (derepressed) grown cells is used to direct cell-free translation, precursor abundance is high throughout growth, although the synthesis of some of the species changes in a complex pattern of ratio and abundance. These data indicate that the abundance of the messengers for the nuclear-coded precursors is regulated in a fashion dependent on the physiologic state of the cell.

Electron Transport Complex IV↗
PubMed1981

Purification of mitochondrial RNA polymerase from Saccharomyces cerevisiae.

The RNA polymerase from the mitochondria of Saccharomyces cerevisiae has been extensively purified by Sepharose 4B, heparin Sepharose 4B phosphocellulose, and DEAE-Sephadex A-50 chromatography. The activity co-sediments with a 45,000-dalton polypeptide at 6.3 S in glycerol gradients. The activity is inhibited by antibodies to the 45,000-dalton polypeptide. The activity is not inhibited by rifampicin or alpha-amanitin. It requires Mg2+ and is inhibited by elevated ionic strength and Mn2+. The most efficient template for the RNA polymerase is poly[d(AT)], with mtDNA being the preferred natural template. The RNA polymerase transcribes mtDNA from the petite strain F11 in a nonrandom manner.

DNA-Directed RNA Polymerases↗
PubMed1980

Antigen-independent binding of IgG dimers to C 1 q as studied by sedimentation equilibrium, complement fixation and electron microscopy.

Rabbit anti-SII pneumococcal polysaccharide IgG antibody was cross-linked by dithiobis (succinimidyl propionate). The IgG dimers were visualized by electronmicroscopy and resembled two Y-shaped structures connected in random orientations. The three arms of the Y's were of equal length. The six globular domains of the IgG protomers could be seen, but the Fab arms and Fc stems could not be distinguished from each other. Electron microscopy revealed that the dimers were bound to the globular heads of C 1 q. From the dependence of thee weight average molecular weight on dimer concentration, and equilibrium constant of about 10(6) M(-1) was derived for the binding of dimers to C 1 q. The number of IgG dimers which could be accommodated at a single C 1 q molecule was derived to be three. The data do not allow a clear distinction between noncooperative and cooperative binding. The binding equilibrium was independent of whether the IgG dimers were liganded with an SII nonasaccharide hapten or not. The results are at variance with an allosteric mechanism of the action of antigen in C1 activation. They lend support to the association hypothesis of complement activation. The data suggest that clusters of about six IgG molecules, connected by a multivalent antigen or arranged at the cell surface, are recognized by C 1 q with a binding constant of about 10(10) M(-1).

Animals↗
PubMed1980

[Effect of high single doses of bromocriptine in schizophrenic patients with elevated serum prolactin levels and extrapyramidal side effects associated with neuroleptic treatment (author's transl)].

The purpose of the present study was to investigate the effect of bromocriptine in single doses of 20 and 30 mg on the unwanted effects most frequently caused by neuroleptics: elevated prolactin levels and extrapyramidal disturbances. 111 chronic schizophrenics were included in the investigations, 58 of them being treated with haloperidol and 53 with chlorpromazine. It was found that a single dose of 30 mg bromocriptine brought about a statistically significant decrease in the prolactin levels of patients treated with haloperidol but produced no more than a downward tendency in patients receiving chlorpromazine (the initial prolactin levels of both groups of patients were equal.) The effect of bromocriptine on EPS disturbances was more marked in the chlorpromazine group, but side effects such as nausea and agitation also occurred more frequently in this group. These results show that there is no correlation between the reduction in prolactin levels produced by bromocriptine and an improvement in unwanted EPS effects. This supports the hypothesis that the effect of neuroleptics on the prolactin secreting cells of the anterior pituitary and their effect on the EPS are mediated by different sets of receptors.

Adult↗
PubMed1979

Kinetics of the helix-coil transition of a polypeptide with non-ionic side groups, derived from ultrasonic relaxation measurements.

Ultrasonic absorption and velocity dispersion curves have been measured in the temperature induced helix-coil transition range of poly-N5-(3-hydroxypropyl)-L-glutamine in a methanol/water mixture. The results clearly reflect an effect due to the kinetics of the conformational conversion. A practically single relaxation time is observed which passes through a maximum when plotted versus the degree of transition. This maximum occurs at definitely less than 50% helix as predicted for by the theory for the comparatively short chain length involved here. The results are discussed in relation to previous theoretical and experimental findings.

Calorimetry↗
PubMed1978

Structure and synthesis of a lipid-containing bacteriophage. Dissociation of bacteriophage PM2 into its morphological subunits.

The lipid-containing bacteriophage PM2 was dissociated stepwise in 1 M NcCl (pH 7.2)with increasing urea concentrations. In 2 M urea the following substructures could be identified: (a) a nucleocapsid containing all of the viral lipid, the DNA, proteins III and IV, plus a fraction of protein II, and (b) a second substructure respresenting particles which contained all viral elements except protein I, the spike protein. In 4 M urea the viral nucleocapsid containing all of proteins III and IV, the DNA, plus a fraction of protein II, was isolated. Upon increasing the urea concentration further, this nucleocapsid is stable up to 8.5 M urea; in 9 M urea protein III was partly dissociated from the nucleocapsid. The nucleocapsid in 4--8.5 M urea is stabilized by the addition of 0.1--3 M NaCl but dissociates if the NaCl concentration is less than 0.1 M. The nucleocapsid was also dissociated in 4--8.5 M urea at pH 4.5. The nucleocapsid structures and some intermediate morphological subunits have been analysed by physical methods, enabling us to draw some conclusions about the structure and hydration of the virus.

Amino Acids↗
PubMed1977

Comparative subcutaneous absorption of local anesthetics: lidocaine, procaine and tetracaine.

The pH partition hypothesis was applied to the absorption of ionizable local anesthetic amines through the subcutaneous (s.c.) route. Solutions of lidocaine hydrochloride (LHCl), procaine hydrochloride (PHCl) and tetracaine hydrochloride (THCl) at various pH were implanted on s.c. animal tissue through a glass absorption cell. The s.c. absorption of these drugs was evaluated from the clearances' slopes evolved by determination of the drugs' concentrations in the cell at definite intervals. The higher the pH level, these conjugated bases become more unionized and lipid partitioned resulting in increased rates of s.c. absorption. The extent of unionization is governed by the pka of each of these drugs; at the high feasible pH--procaine which is least unionized--its s.c. absorption rate is nearly a third of that of lidocaine or tetracaine. The pH effect on s.c. absorption of local anesthetics was substantiated by estimation of lethal time50 (LT50) in mice.

Animals↗
PubMedDate not supplied

The role of the head and tail domain in lamin structure and assembly: analysis of bacterially expressed chicken lamin A and truncated B2 lamins.

Nuclear lamins like cytoplasmic intermediate filament proteins exhibit a characteristic tripartite domain structure with a segmented alpha-helical rod domain flanked by an N-terminal head and a C-terminal tail domain. To examine the influence of the head and tail domains on the structure and assembly properties of nuclear lamins, we have engineered "headless," "tailless," and "rod" chicken lamin B2 cDNAs and expressed them in Escherichia coli. A full-length chicken lamin A cDNA was also expressed in E. coli, and the recombinant protein compared with the structure and assembly properties of full-length chicken lamin B2 (E. Heitlinger et al. (1991) J. Cell Biol. 113, 485-495). As with lamin B2, at their first level of structural organization, lamin A and the headless lamin B2 formed myosin-like dimers consisting of a 51- to 52-nm-long tail flanked by two globular heads at one end. Similarly, the tailless and rod lamin B2 fragments formed tropomyosin-like dimers consisting of a 51 to 52-nm-long rod. In contrast to the lateral mode of association of cytoplasmic IF dimers into four-chain tetramers, at their second level of structural organization, lamin A dimers, just as lamin B2 dimers (E. Heitlinger et al. (1991) J. Cell Biol. 113, 485-495), associated longitudinally to form polar head-to-tail polymers. Whereas dimers made of the truncated B2 headless and rod lamins had lost their propensity to associate head-to-tail, tailless lamin B2 dimers revealed an enhanced head-to-tail association. Finally, at their third level of structural organization, rather than assembling into stable 10-nm filaments, both lamin A and the three truncated B2 lamins formed paracrystalline arrays exhibiting distinct transverse banding patterns with axial repeats of either 24 or 48-49 nm depending on the species.

Animals↗
PubMedDate not supplied

Fall of cholesterol with time on dialysis: impact on atherogenicity.

The majority of patients treated for chronic renal failure die from cardiovascular complications. Lipid abnormalities in this group are thought to contribute to this high mortality. The authors have shown that hemodialysis patients with longer months on dialysis tend to have lower total cholesterol (TC) levels. This study extends data to examine lipid disturbances in 53 continuous ambulatory peritoneal dialysis (CAPD) and 126 hemodialysis patients using multivariate analysis. Longitudinal values after 9-10 months were measured in 16 CAPD patients and 52 hemodialysis patients. Analysis of covariance for all patients demonstrated an inverse correlation of TC (p = 0.003), high-density lipoprotein (HDL) cholesterol (p = 0.01), and apolipoprotein A-I levels (p less than 0.02) with months on dialysis. In addition, the TC level was higher in women (p less than 0.001) and CAPD patients (p less than 0.001), and correlated with age (p = 0.02) and albumin (p less than 0.001). HDL cholesterol was higher in blacks (p less than 0.001) but was not affected by gender, dialysis modality, age, or albumin. Diabetic status, serum parathyroid hormone, and blood pressure were not significant variables for TC or HDL-C. The atherogenic risk indicators, TC/HDL cholesterol (p less than 0.001) and apolipoprotein B (p less than 0.02) were higher in whites than in blacks. Longitudinal study revealed lower TC levels in individual hemodialysis patients (p less than 10(-6) by paired t-test), the fall being greater for patients with fewer total months on dialysis (p less than 0.04, by analysis of covariance). CAPD patients had no change in TC by paired t-test.(ABSTRACT TRUNCATED AT 250 WORDS)

Apolipoproteins↗