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Biomedical subjects

S Hall

Publications and source records attributed to S Hall.

At least 271 records · Page 15Linked to original sources
PubMed1978

Assignment of tra cistrons to EcoRI fragments of F sex factor DNA.

We describe here the cloning of single EcoRI fragments from the tra region of F DNA using ColE1::Tn3 as vector. These plasmids, as well as the series of Skurray et al. (Proc. Natl. Acad. Sci. U.S.A. 73:64-68, 1976), have been used to refine the map positions of tra cistrons on the F factor as well as to define a new DNA transfer cistron, traM. The current map of the tra cistrons is presented. None of the known tra cistrons, with the exception of traG, straddles an EcoRI site. The EcoRI site at 82 kilobases splits the traG cistron into two portions, an operator-proximal portion necessary for F pilus synthesis and an operator distal portion involved in conjugation itself. The operon structure of the tra cistrons was reevaluated, and we found that traI is at least partially independent of transcription of the traA to traD operon.

Conjugation, Genetic↗
PubMed1978

Fetal and placental growth in the rat following differential reduction of litter size.

The effects on fetal and placental growth of differential litter size reduction on day 10 (LR10) and day 13 (LR13) were determined in the rat. LR10 resulted in significant increments in placental weight, fetal body and brain weight, and brain protein content in the survivors at day 21. A marginal effect on brain cellularity (DNA) was observed. Values for these parameters generally followed the extent of reduction. Placenta weight was also related to original litter size. In contrast, LR13 which was associated with survival of supernumerary placentae (those without a fetus) produced no growth enhancement. Prenatal development was discussed in terms of general systemic influences and hormonal regulatory mechanisms.

Animals↗
PubMed1978

Epidemiologic investigation of employees chronically exposed to methylene chloride. Mortality analysis.

A large male employee population with continuous low level work exposures to methylene chloride for up to 30 years was examined for mortality experience using non-concurrent prospective and proportionate mortality techniques. Mortality of the study group was consistent with industrial controls and less than the New York State general population. Life table analysis of the 1964 methylene chloride exposed cohort was followed through 1976 and demonstrated age group specific probabilities or 13 year survivorship equal to or better than that of three control male populations: Kodak Park, New York State, and United States.

Adolescent↗
PubMedDate not supplied

Frequency and significance of antibody to double-stranded DNA in chronic active hepatitis.

To assess the frequency and significance of immunoglobulin G antibody to double-stranded DNA in chronic active hepatitis, 99 patients with severe disease were tested for the antibody by an enzyme-linked immunosorbent assay of established sensitivity and specificity. Antibody was detected in 56 patients (57%) and occurred with similar frequency in patients with autoimmune (64%), idiopathic (46%) and type B (43%) disease. The mean serum level of antibody was higher in autoimmune disease but it was not significantly different from that in the other diagnostic categories. Patients with and without the antibody could not be distinguished by clinical, laboratory or histologic findings. Responses to corticosteroid therapy and mortality were unrelated to antibody status. In five patients, the antibody disappeared after corticosteroid treatment and induction of histologic remission. We conclude that immunoglobulin G antibody to double-stranded DNA is frequently present in patients with severe chronic active hepatitis. Patients with autoimmune disease may have higher antibody levels than others, but the presence of antibody does not connote a disease of specific etiology, unique presentation or different behavior. The prevalence of the finding and its disappearance after corticosteroid therapy suggest that it is a nonspecific manifestation of inflammatory activity.

Adrenal Cortex Hormones↗
PubMedDate not supplied

Oestrogenic activity of benzylparaben.

Previous work has demonstrated that the alkyl esters of p-hydroxybenzoic acid (parabens) possess oestrogenic activity, which increases with length of alkyl chain from methylparaben to n-butylparaben and with branching in the alkyl chain from n-butylparaben to isobutylparaben. This study reports on the oestrogenic activity of benzylparaben in a variety of assays in vitro and in vivo. Benzylparaben was able to displace [(3)H]oestradiol from cytosolic oestrogen receptor (ER) of MCF7 human breast cancer cells by 22% at 1000-fold molar excess, by 40% at 10,000-fold molar excess, by 57% at 100 000-fold molar excess and by 100% at 1,000,000-fold molar excess. It was able to increase expression of a stably transfected oestrogen responsive reporter gene (ERE-CAT) in MCF7 cells after 24 h at 10(-5)M/10(-4)M and after 7 days at 10(-6)M/10(-5)M/10(-4)M. Proliferation of MCF7 cells could be increased by 10(-6)M/10(-5)M benzylparaben and this could be inhibited by 10(-7)M pure anti-oestrogen ICI 182,780, indicating that growth effects were ER mediated. Further evidence for ER-mediation was provided from the ability of benzylparaben to increase the growth of a second oestrogen-dependent human breast cancer cell line ZR-75-1, but not the oestrogen-insensitive MDA-MB-231 cell line. When tested in the presence of 10(-10)M 17beta-oestradiol, benzylparaben gave no antagonist response on the growth of either MCF7 or ZR-75-1 cells. Finally, benzylparaben could increase uterine weight in the immature mouse following topical application of three daily doses of 33 mg to dorsal skin. These results demonstrate that the oestrogenicity of methylparaben can be increased by the addition of an aryl group as well as by lengthening or branching the alkyl grouping.

Administration, Topical↗
PubMedDate not supplied

Mammalian tachykinins stimulate rat uterus by activating NK-2 receptors.

Neurokinin A (NKA), substance P (SP), and neurokinin B (NKB) enhanced the contractile force of uterine preparations from estrogen-treated rats. Neurokinin A was more and NKB less potent than SP. The actions of SP were enhanced by phosphoramidon (1 microM) but were unaffected by captopril (10 microM) or bestatin (10 microM). The actions of the peptides were enhanced in the combined presence of phosphoramidon, captopril, and bestatin; the potency order remained NKA > SP > NKB. Atropine inhibited responses to NKB but not to NKA, and slightly reduced those to SP. Specific binding of [125I]-iodohistidyl-neurokinin A (INKA) to uterine membranes was displaced by the tachykinins with a potency order of NKA > SP > NKB. These findings indicate that in the rat uterus 1) tachykinins act at an NK-2 receptor, and that another tachykinin receptor on cholinergic nerves may also be present; and 2) endopeptidase-24.11 participates in the inactivation of the tachykinins.

Animals↗
PubMedDate not supplied

Intraoperative hypotension due to unrecognized bleeding from a continuous spinal catheter site.

We recently cared for a patient who had a rare complication from a continuous spinal catheter: extensive bleeding around the catheter insertion site. This complication went unrecognized intraoperatively because the bleeding was hidden from view. The possible etiologies for this bleeding are discussed, as well as methods to recognize this complication before significant bleeding occurs.

Anesthesia, Spinal↗