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Biomedical subjects

B Hoffman

Publications and source records attributed to B Hoffman.

At least 109 records · Page 6Linked to original sources
PubMed1987

Minoxidil-induced systemic lupus erythematosus.

A patient treated for two months with the antihypertensive agent minoxidil developed pleural and pericardial effusions in association with a positive antinuclear antibody titer. No evidence of central nervous system or renal involvement was present, and results of specific tests for idiopathic systemic lupus erythematosus, including anti-double-stranded DNA and anti-Smith antibodies, were negative. Complement levels were normal. The patient's clinical picture improved and titers of antinuclear antibody decreased after discontinuation of minoxidil therapy, suggesting that minoxidil induced a lupus-like syndrome in this patient.

Aged↗
PubMed1982

Effects of taxol and Colcemid on myofibrillogenesis.

To determine the relationship between thin filaments, Z-bands, microtubules, intermediate filaments (IFs), T-tubules, and sarcoplasmic reticulum (SR) during myofibrillogenesis, myotubes were selectively depleted of their myofibrils with 12-tetradecanoylphorbol 13-acetate (TPA) and then were allowed to regenerate in (i) normal medium, (ii) taxol, and (iii) Colcemid. Myofibrils assembled in normal medium formed typical A-, I-, Z-, M-, and H-bands and associated IFs, T-tubules, and SR. Myofibrils assembled in taxol formed "A-bands" of aligned thick filaments interdigitating with long microtubules and "I-bands" consisting only of microtubules. These unprecedented sarcomeres lacked thin filaments, Z-bands, and associated IFs and SR. "Solitary A-bands," consisting exclusively of laterally aligned bipolar thick filaments 1.6 microM in length without either thin filaments or microtubules, were observed. Myofibrils assembled in Colcemid formed all myofibrillar components in the absence of microtubules but these did not achieve rigorous lateral alignment. Colcemid and taxol induced the formation of patchy Z-bands that invariably served as insertion sites for thin filaments, irrespective of the presence or absence of adjacent thick filaments. Z-bands may function as actin-organizing centers for each sarcomere.

Actins↗
PubMed1982

Zinc and copper binding proteins in human milk.

The proteins binding zinc and copper in human milk have been fractionated and identified, and the distribution of these trace elements among the different binding compounds has been determined. Casein was separated by ultracentrifugation and was found to contain 14% (range 5 to 21%) of the total zinc content in the milk and 28% (range 7 to 48%) of the total copper. Another zinc- and copper-binding protein was isolated by gel filtration and ion-exchange chromatography and identified as serum albumin by gel electrophoresis. Serum albumin in breast milk binds 28% of total zinc and 39% of total copper. The remainder of Zn and Cu was found to be in a low molecular weight form (29% (range 24 to 36%) of Zn; 24% (range 15 to 47%) of Cu) or associated to the fat (29% (range 20 to 45%) of Zn; 9% (range 1 to 21% of Cu). It is hypothesized that association constants of the different binding compounds as well as their concentrations will determine the relative distribution of zinc and copper among them and may affect bioavailability of these elements for the infant.

Breast Feeding↗
PubMed1981

Reversion from deficiency of galactose-1-phosphate uridylytransferase (GALT) in an SV40-transformed human fibroblast line.

Control SV40-transformed human fibroblasts can be readily adapted to growth on medium containing galactose as sole hexose source (galactose-MEH). However, most cells from a line of SV40-transformed skin fibroblasts from a patient with galactosemia (galactose-1-phosphate uridylyltransferase (GALT) deficiency) died in galactose-MEM. Surviving cells of this line either grew in completely sugar-free media or had acquired significant amounts of GALT activity. Two presumptive revertant cell lines with GALT activity were characterized in detail. The expression of GALT in these two lines was stable in nonselective conditions. Each had different reaction maximum velocities with respect to uridine diphosphoglucose (UDPg) concentration as compared to residual activity in the parental cell strain or control cells. Both appeared to demonstrate heat-inactivation profiles for GALT than differed from the parental cells or controls. UDPG concentration was found to significantly alter the thermostability of GALT. A competitive radioimmunoassay for GALT showed that these two lines had amounts of the GALT protein comparable to that of the parental cell strain or control cells. The electrophoretic mobility of GALT from the two presumptive revertants was found to differ from control cells. It was concluded that structural gene changes were probably responsible for the apparent reversion in these lines.

Cell Line↗
PubMed1975

Bacteriophage P22 virion protein which performs an essential early function. I. Analysis of 16-ts mutants.

The product of gene 16 of phage P22, P16, is a head protein. P16 does not play an essential role in phage assembly since particles formed without this protein appear normal by electron microscopy examination (Botstein et al., 1973). P16 is essential when the particle infects a cell in the following cycle of infection (Botstein et al., 1973; King et al., 1973). We have characterized a mutant of P22 carrying a temperature-sensitive allele of gene 16. This mutant has previously been referred to as P22 25-ts (Levine et al., 1970, 1972) and P22 X-ts (Bezdek and Soska, 1970, 1973). P22 16-ts behaves as an early mutant at the nonpermissive temperature. Temperature shift experiments show that P16 of the infecting virion acts within the first 10 min at 25 C and that gene 16 product is required late in the latent period for incorporation into infectious phage. Induction does not require P16 for the production of particles. Particles produced either in a P22 16-ts thermal shift-up infection or after induction of 16-ts lysogens at 41 C are missing P16 and are, therefore, defective. P16 in P22 16-ts virions formed at the permissive temperature appears to be heat labile; it is inactivated after infection at 41 C. A simple assay for defective particles based on a complementation test is described.

DNA, Viral↗
PubMed1975

Bacteriophage P22 virion protein which performs an essential early function. II. Characterization of the gene 16 function.

P16 is a virion protein and, as such, is incorporated into the phage head as a step in morphogenesis. The role of P16 in assembly is not essential since particles are formed without this protein which appear normal by electron microscopy. P16 is essential when the particle infects a cell in the following cycle of infection. In the absence of functional P16, the infection does not appear to proceed beyond release of phage DNA from the capsid. No known genes are expressed, no DNA is transcribed, and the host cell survives the infection, continuing to grow and divide normally. The P16 function is required only during infection for the expression of phage functions. Induction in the absence of P16 proceeds with the expression of early and late genes and results in particle formation. P16 must be incorporated during morphogenesis into progeny particles after both infection and induction for the progeny to be infectious. The P16 function is necessary for transduction as well as for infection. Its activity is independent of new protein synthesis and it is not under immunity control. P16 can act in trans, but appears to act preferentially on the phage or phage DNA with which it is packaged. The data from complementation studies are compatible with P16 release from the capsid with the phage DNA. In the absence of P16 the infection is blocked, but the phage genome is not degraded. The various roles which have been ruled out for P16 are: (i) an early regulatory function, (ii) an enzymatic activity necessary for phage production, (iii) protection of phage DNA from host degradation enzymes, (iv) any generalized alteration of the host cell, (v) binding parental DNA to the replication complex, and (vi) any direct involvement in the replication of P22 DNA. P16 can be responsible for: (i) complete release of the DNA and disengagement from the capsid, (ii) bringing the released DNA to some necessary cell site or compartment such as the cytoplasm, (iii) removal of other virion proteins from the injected DNA, and (iv) alterations of the structure of the injected DNA.

Adsorption↗