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Biomedical subjects

D Hoffman

Publications and source records attributed to D Hoffman.

At least 91 records · Page 5Linked to original sources
PubMed1988

Smoking and cervical intraepithelial neoplasia: nicotine and cotinine in serum and cervical mucus in smokers and nonsmokers.

A blood sample before treatment was taken from 35 women with cervical intraepithelial neoplasia. Levels of nicotine and cotinine were analyzed by radioimmunoassay. Both cotinine and, especially, nicotine were shown to be strongly concentrated in cervical mucus compared with serum levels. These findings confirm the association shown in epidemiologic studies of smoking and cervical neoplasia. It cannot be concluded that smoking is a genuine cause of cervical neoplasia. However, the results support the concept that smoking is a true risk factor in cervical neoplasia.

Adult↗
PubMed1988

Group therapy in manic-depressive illness.

Noting the recent growth of self-help groups for manic-depressive illness and considering the scarcity of empirical studies on the effectiveness of group therapy in the treatment of this illness, this review examines the three available reports on groups and adds a fourth report on the authors' experience with a group over four-and-a-half years. The evidence argues in favor of combined lithium and group therapy. Some research questions and strategies for investigation follow.

Adaptation, Psychological↗
PubMed1987

Unusual structure, evolutionary conservation of non-coding sequences and numerous pseudogenes characterize the human H3.3 histone multigene family.

The genomic organization of the replication-independent, basally expressed, human H3.3 gene is atypical of traditional histone gene organization. The gene contains 3 introns totalling 7.8 kb and unusual direct repeats flank all three intron-exon splice junctions. The transcription initiation site was mapped by S1 nuclease protection analysis and confirms that cDNA clones previously reported were full length. Sequence similarities between regions at the 5' and 3' termini of this human gene and a chicken H3.3 gene lead us to propose that either the previous assignments of termini of the chicken gene are in error, or there are alternative transcription start and polyadenylation sites. The 85% base matching of human and chicken H3.3 3'UTR sequences for 520 bases is unprecedented among homolog 3'UTR segments, especially considering that these species are separated by over 250 Myr of evolution. We also present the sequence of three related processed human H3.3 pseudogenes and provide evidence demonstrating that most of the 20 to 30 copies of the H3.3 gene within the human genome are in fact processed pseudogenes.

Amino Acid Sequence↗
PubMed1987

Anadara ovalis hemoglobins: distinct dissociation and ligand binding characteristics.

The red cells of the arcid clam Anadara ovalis contain two electrophoretically distinct hemoglobins: Hb Major (Hb Ma) and Hb Minor (Hb Mi). The major component consists of two electrophoretically indistinguishable tetramers each composed of two heterodimers; the minor hemoblogin is a homodimer whose subunits are different from the tetramer. Functionally, Hb Ma has a higher P50, exhibits a concentration dependent oxygen affinity, has significant ligand cooperativity (n = 2.0), lacks a Bohr effect and is unaffected by ATP. HB Mi has a P50 which is lower and independent of hemoglobin concentration, shows appreciable cooperativity (n = 1.4) and exhibits no heterotropic effects. Both Hb Ma and Mi are resistant to dissociation in the presence of 1.0 M NaI, NaCl and guanidine-HCl but dissociate to monomers when converted to the aquamet but not the cyanmet derivative. The dissociation is completely inhibited by mercaptoethanol. The large number of reactive -SH groups (10-13 per tetramer) suggests that the monomerization is mediated by intra-subunit disulfide bridge formation.

Animals↗
PubMed1986

NMR measurement of intracellular water volume in rat kidney proximal tubules.

Knowledge of cell water volume is essential for the measurement of concentrations of intracellular ions and metabolites in kidney proximal tubules. We have developed a method which utilizes 35Cl-NMR as a measure of extracellular volume and 2H-NMR, in combination with a membrane-impermeable shift-reagent [Dy-DTPA]2-, as a measure of the ratio of intra- and extracellular water volumes. Measurement of extracellular volume by 35Cl-NMR is possible, since the resonance of intracellular 35Cl is too broad to be detectable in kidney cells. The 2H-NMR measurement exploits the fact that only extracellular water is in direct contact with [Dy-DTPA]2-. However, rapid exchange of water across the cell membrane results in only a single 2H2O resonance at a chemical shift which is a weighted average of the shifted extra- and unshifted intracellular water resonances. Expression of the extracellular volume as a fraction of the total volume by fCl and as a fraction of the total water-volume by fD, permits the calculation of the fractional cell-water content fw = [(1/fD)-1]/[(1/fCl)-1]. This approach was applied to proximal tubular suspensions prepared from the rat kidney. The water content was found to be 76.9 +/- 1.8% (n = 6) at 37 degrees C. Increasing extracellular osmolality from 295 to 390 mOsm/kg H2O, by addition of mannitol, decreased the water content by 21%. Our results are in good agreement with those obtained by the gravimetric method.

Animals↗
PubMed1986

The relative bioavailability of levonorgestrel and ethinyl estradiol administered as a low-dose combination oral contraceptive.

The relative bioavailability of levonorgestrel (LNG) and ethinyl estradiol (EE) administered concomitantly both as an oral tablet and as a solution was assessed in a randomized two-period crossover study in 24 healthy women. Serum concentrations were monitored for 96 h after each administration. The relative bioavailability (Fr) of LNG in the tablet with respect to the solution was 107%; thus the two formulations were bioequivalent with respect to LNG. The relative bioavailability of EE, however, was significantly lower for the tablet (Fr 83%) compared to the solution. This difference may have been due to either decreased absorption or enhanced presystemic elimination of EE from the tablet formulation.

Adult↗
PubMed1986

Hyperalimentation worksheet.

Parenteral hyperalimentation is an important means of nutritional support for critically ill patients. Calculating the amount of additives necessary for the appropriate compounding of hyperalimentations is a tedious process with many opportunities for error. A new computer program written in Pascal has been created to reduce pharmacy processing time. Menus and single-keystroke entry are implemented wherever practicable. A hard-copy printout and an individualized label are generated on command. Program testing has resulted in an 88% reduction of processing time.

Computers↗
PubMed1985

Elimination kinetics of blood lead in workers with chronic lead intoxication.

Blood lead elimination half-lives were determined for 65 patients with occupational chronic lead intoxication who were removed from exposure, treated with intravenous EDTA, and followed for periods of up to 2,419 days. The median overall blood lead elimination half-life was 619 days in patients with normal renal function and 1,907 days in patients with renal impairment. Slow-phase elimination half-lives in patients followed for longer than 5 years ranged from 1,658 to 7,189 days. Blood lead concentrations declined during periods of chelation with a mean half-life of 7 days and rebounded to near prechelation concentrations following termination of chelation with a mean doubling time of 27 days. The overall blood lead elimination half-life was positively associated with length of follow-up (p less than 0.001), age (p = 0.04), and duration of exposure (p = 0.02), but was not associated with the initial blood lead concentration following cessation of exposure or the total amount of EDTA received.

Adult↗
PubMed1985

Stressor invoked exacerbation of amphetamine-elicited perseveration.

The provocation of stimulus preservation induced by amphetamine in a Y-maze was appreciably enhanced in animals that had been exposed to uncontrollable shock, whereas controllable shock did not influence performance. The enhancement of the stimulus perseveration was evident irrespective of whether the stressor was applied immediately or 72 hr prior to the perseveration test, provided that the stimulus complex in which shock was delivered was similar to that in which the perseveration test was conducted. When the two environments were distinctively different from one another the enhancement of stimulus perseveration was evident immediately after shock exposure, but not 72 hr after shock. It is suggested that stressors may have long-term effects of amphetamine-elicited perseveration, but the expression of such an effect is dependent upon the stimulus context in which the behavior is examined. Moreover, it is suggested that evaluation of amphetamine-induced behavioral changes, and possibly amphetamine-elicited and idiopathic psychosis, should consider the stress history of the organism.

Amphetamine↗
PubMed1985

Serum dehydroepiandrosterone sulfate and the use of clomiphene citrate in anovulatory women.

Serum dehydroepiandrosterone sulfate (DHEA-S) is frequently elevated in anovulatory women. This study was carried out to determine whether the ovulatory response with clomiphene citrate (CC) in patients with elevated levels of serum DHEA-S is influenced by the pretreatment level. Also evaluated was whether this response rate was similar to or different from that of anovulatory patients who had normal levels of DHEA-S. CC was administered to 40 anovulatory patients who had elevated levels of DHEA-S. Rankit analysis of these 40 elevated DHEA-S levels indicated that two populations existed. These patients were, therefore, divided into two groups of 29 and 11 with DHEA-S levels of less than 5 and greater than 5 micrograms/ml, respectively. Fifty-nine anovulatory patients with normal DHEA-S levels were also treated with CC. Patients with elevated and normal DHEA-S levels had similar rates of ovulation with CC (75% and 78%). Among patients with elevated levels of DHEA-S, ovulation occurred in 55% of patients with levels greater than 5 micrograms/ml and 83% with levels less than 5 micrograms/ml. The dose of CC at which ovulation occurred was unrelated to the level of DHEA-S. Pregnancies occurred in 15 of the 40 patients after at least four ovulatory cycles and were not influenced by the level of DHEA-S. It is concluded that CC is effective in inducing ovulation in patients with elevated levels of adrenal androgens. However, in patients with DHEA-S levels greater than 5 micrograms/ml, the ovulatory response rate may be decreased.

Adult↗
PubMed1985

Subacute sclerosing panencephalitis: measles virus matrix protein nucleic acid sequences detected by in situ hybridization.

Subacute sclerosing panencephalitis (SSPE) is characterized by a hyperimmune state toward the polypeptides of measles virus except the matrix (M) protein. Using cloned (3H)-labeled complementary DNA probes for in situ hybridization, we found the M protein and nucleocapsid (NP) protein nucleotide sequences in glial cells and neurons of cryostat sections from two SSPE brains. In one SSPE brain, M protein was lacking, but the other measles polypeptides were present. IgG and IgM antibodies eluted from that brain lacked antibodies to M protein, but antibodies to other measles polypeptides were present. In SSPE brain, the viral M-protein defect is not a deletion of the M gene, but rather a block in gene expression.

Brain Chemistry↗