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Biomedical subjects

B L Brown

Publications and source records attributed to B L Brown.

At least 109 records · Page 6Linked to original sources
PubMed1983

A possible role for calmodulin in human thyroid cell metabolism.

A protein which shared several characteristics with authentic calmodulin was extracted from human thyroid homogenates. The protein bound to fluphenazine--Sepharose and could be specifically eluted using EGTA. The eluted protein had a u.v. spectrum characteristic of calmodulin and migrated like authentic calmodulin with a calcium-dependent shift on sodium dodecyl sulphate polyacrylamide-gel electrophoresis. Calmodulin in thyroid cell extracts was shown to be biologically active, measured by its ability to activate a calmodulin-deficient cyclic GMP phosphodiesterase; this activation could be inhibited by trifluoperazine. A possible role for calmodulin in the action of TSH on the thyroid was demonstrated by studying the effects of phenothiazines and the naphthalene sulphonamide, W7, a more specific calmodulin inhibitor, on TSH-stimulated cyclic AMP levels in cultured thyroid cells. The phenothiazines and W7 were found to inhibit the accumulation of cyclic AMP in response to TSH in a concentration-dependent manner although low concentrations of W7 enhanced TSH-stimulated cyclic AMP accumulation.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1981

Stimulation of the adenylate cyclase of A B16 melanoma cell line by pro-opiocortin-related peptides--a structure-activity study.

The ability of alpha-melanotrophin (alpha-MSH or ACTH 1-acetyl-13 amide) and other structurally related peptides derived from the common precursor, pro-opiocortin, to stimulate adenylate cyclase activity in a pigmented B16 mouse melanoma was investigated. The peptides ACTH 1-39, ACTH 1-24, alpha-MSH, ACTH 1-13 amide and beta-MSH all stimulated the enzyme to a similar maximal extent and with similar potency (ED50 = 1.3 . 10(-6) M) except that ACTH 1-39 was slightly less potent (ED50 = 5 . 10(-6) M). ACTH 4-10 (ED50 = 4 . 10(-5) M) and gamma-MSH (ED50 = 5 . 10(-6) M) were partial agonists. ACTH 1-10 was no more effective than ACTH 4-10 in stimulating the enzyme whereas ACTH 1-13 amide was a full agonist. The peptides beta-endorphin and its derivatives, Met-enkephalin and melanotrophin potentiating factor (MPF), failed to stimulate the enzyme. We suggest that the B16 melanoma requires not only the sequence ACTH 4-10 but also some part of the sequence ACTH 11-13, or a similar sequence in the terminal portion of beta-MSH, for full activation of the receptor-linked enzyme.

Adenylyl Cyclases↗
PubMed1981

Risk management.

A practicing hospital administrator explores how a risk management program can function effectively in a hospital setting. Risk management is defined and methods of planning, developing, and organizing a practical risk management program are outlined. Certain principles are presented to ensure its effectiveness and the advantages and disadvantages of such a program are discussed in this article.

Financial Management↗
PubMed1981

In vitro host range of equine infectious anemia virus.

Equine infectious anemia virus (EIAV) was successfully inoculated onto cell cultures of canine and feline origin, resulting in chronic infections in these cultures. Infection of equine cell cultures, which were the previous sole in vitro source demonstrated for virus production, was also performed for comparative purposes. Determination of the nature of the virus produced in the heterologous as well as the equine cells was accomplished in several ways. SDS-PAGE of purified virus from the different cell lines indicated very similar protein composition. Immunological identity was observed in gel diffusion tests employing an antiserum to the major core protein (p24) of equine-derived EIAV. Competition radioimmunoassays also indicated similar antigenicity in the viruses derived from the several cell lines. Strong relatedness was further demonstrated by hybridization of viral RNAs to EIAV complementary DNA. These data indicate that EIAV has an amphotropic cell culture host range and that the viruses isolated from the permissive lines were similar.

Animals↗
PubMed1981

Lack of effect of angiotensin on levels of cyclic AMP in isolated adrenal zona glomerulosa cells from the rat.

The effects of pure [Asp1,Val5]- and [Asn1,Val5]-angiotensin II and also [des-Asp1,Ile5]-angiotensin II (angiotensin III) on cyclic AMP and steroid outputs by dispersed rat capsular cells, comprising 95% zona glomerulosa and 5% zona fasciculata cells, have been studied. The results showed that [Asp1, Val5]-and [Asn1, VAl5]-angiotensin II, at doses between 2.5 X 10(-11) and 2 X 10(-4) mol/l, which produced typical increases in steroidogenesis, failed to increase output of cyclic AMP. This lack of effect was observed whether the nucleotide was measured by radioimmunoassay or by adrenal binding protein and under the same conditions in which 8.4 mM-K+ consistently increased the output of cyclic AMP. Instead the results showed a small but significant decrease in cyclic AMP output with angiotensin II. Similar results were obtained with incubations for 60 rather than 120 min and with medium containing a concentration of 5 or 40 g bovine serum albumin/l. Although the levels of cyclic AMP were generally higher in the presence of the phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine, the same decrease relative to basal outputs was observed with angiotensin II which increased steroidogenesis. Angiotensin III also failed to increase output of cyclic AMP at doses (2.5 X 10(-9) to 2.5 X 10(-6) mol/l) which produced increases in steroid output equivalent to those with angiotensin II. These results indicate that angiotensin II and III can act through a cyclic AMP-independent mechanism.

Adrenal Glands↗
PubMed1981

The determination of the sex of an individual from a dried bloodstain using radioimmunoassay of testosterone, progesterone, and estradiol-17 beta.

A radioimmunoassay (RIA) technique was developed for the purpose of determining the sex of an individual by measuring the steroids testosterone (T), progesterone (P), and estradiol-17 beta (E2) in dried bloodstains. The steroid values from a single bloodstain are reported as ratios T/P, T/E2, and P/E2. The results reported include data on the validation of this technique, results of analysis of 146 duplicate bloodstains representing 112 samples from females and 34 samples from males as controls, and results of analysis of 114 duplicate bloodstains representing 60 from females and 54 from males that were submitted as a blind study to test the accuracy of this RIA technique in determining the sex of an individual from a dried bloodstain.

Blood Stains↗
PubMed1981

Intrauterine meconium aspiration.

Two hundred consecutive autopsies of stillborn infants were reviewed. Twenty-five cases of histologically evident amniotic fluid aspiration were identified. Among these 25 cases, 8 had identifiable intraalveolar meconium. The clinical setting and histologic features of these cases are reviewed, and the significance of intrauterine meconium aspiration is discussed.

Adult↗
PubMed1980

Thyroid hormone relationships in the fetal and newborn lamb.

Plasma thyroxine (T4) and reverse triiodothyronine (rT3) concentrations have been measured in chronically catheterised sheep fetuses during the last third of gestation. In some animals T4 and rT3 concentrations fell before delivery but there was no change in the t4/rT3 ratio. In several serially sampled fetuses a small rise in plasma triiodothyronine concentration has been demonstrated in the days preceding delivery. Infusion of cortisol to fetuses commencing at 130 days of gestation (term 147 days) with the simultaneous administration of progesterone to delay labour resulted in changes in T4 and rT3 concentrations which were similar to those normally seen at term. The nature of the changes in the peripheral metabolism of T4 around the time of birth are discussed.

Animals↗