PubMed Health⌕ Search

Biomedical subjects

B L Brown

Publications and source records attributed to B L Brown.

12 recordsLinked to original sources
PubMed1979

Nasal polypectomy in patients with asthma and sensitivity to aspirin.

Nasal polypectomy is safe in patients with asthma and intolerance to aspirin. Asthma should be controlled before polypectomy. Patency of the nasal airway after the operation and the effect of polypectomy on asthma are independent of severity of the asthma, history of atopy, and administration of steroids. We reviewed retrospectively the courses of 101 patients with the asthma triad who had nasal polypectomies between 1970 and 1974. Before polypectomy, 39 patients were hospitalized to control active asthma: during the postoperative hospitalization, 19 had wheezing, mostly mild. Of the 62 patients with inactive asthma, three had wheezing postoperatively. Asthmatic condition at one year after polypectomy, compared with the condition at one year before, was improved in 30 patients, worse in 14, and unchanged in the rest. Nasal airways remained good for at least one year in 60% of the patients.

Adolescent↗
PubMed1979

Implants of Supramid, Proplast, Plasti-Pore, and Silastic.

Four types of synthetic materials were implanted in 54 rabbits: Supramid, Proplast, Plasti-Pore, and Silastic. Each material was implanted into the auricle and concomitantly into the subdermis of the face. Postoperative assessment was every one to three days, while killing was done at six weeks, six months, and one year postoperatively for microscopic evaluation. Supramid mesh contains black pigment, which became incorporated within the histiocytes and giant cells around the implanted mesh by six weeks; at one year, the soft tissues were pigmented microscopically. Proplast was not extruded despite an intense and persistent histiocytic and giant-cell reaction; its black color constituted a major drawback for implantation beneath thin skin. The Plasti-Pore used in these studies was rigid and somewhat difficult to sculpture, and it induced a persistent but minor cellular reaction. Silastic was easily displaced.

Animals↗
PubMed1978

Effect of TRH and dopamine on cyclic AMP levels in enriched mammotroph and thyrotroph cells.

Populations of normal anterior pituitary cells enriched in thyrotrophs or mammotrophs prepared by velocity sedimentation were used to investigate the effect of modulators of TSH and prolactin secretion on cyclic AMP accumulation. In both thyrotroph-enriched and mammotroph-enriched fractions, IBMX increased cyclic AMP accumulation. In the presence of IBMX, TRH invoked an increase in cyclic AMP suggesting that TRH modulates cyclic AMP accumulation in both of these cell types from normal pituitary glands. In the mammotroph-rich fraction, dopamine inhibited the increase in cyclic AMP induced by TRH. In contrast however, in the thyrotroph-enriched fraction dopamine lowered neither cyclic AMP concentration nor TSH secretion. Thus the inhibiting effect of dopamine on cyclic AMP appears to be specific for prolactin-secreting cells.

1-Methyl-3-isobutylxanthine↗
PubMed1978

Induced cell aggregation and mating in Streptococcus faecalis: evidence for a bacterial sex pheromone.

Recipient strains of Streptococcus faecalis produce a trypsin sensitive, heat resistant, nuclease resistant factor, designated clumping-inducing agent (CIA) which causes strains carrying certain conjugative plasmids to aggregate. RNA and protein synthesis but not DNA synthesis are required for aggregation to occur. Recipient filtrates that contain CIA activity also induce donors to mate at high frequencies. Introduction of a transferable plasmid into strains producing CIA dramatically reduces the amount of CIA activity produced by the strain but allows the strain to respond to exogenously added CIA. Our data suggest that CIA represents a bacterial sex hormone (pheromone).

Animals↗
PubMed1977

Studies on the control and dynamics of thyrotropin secretion from isolated adenohypophyseal cells.

Thyrotropin (TSH) secretion from isolated anterior pituitary cells has been studied using the technique of cell column perifusion. The consistency in secretory rate and temporal profiles of TSH output in response to stimulation illustrated that the system is suitable for studying the kinetics of stimulation and inhibition of secretion. During perfusion TSH release was stimulated in response to a variety of secretogogues, namely TRH, raised potassium concentrations and phosphodiesterase inhibitors. The onset and termination of the secretory responses were rapid and displayed a temporally biphasic pattern of secretion. Dose-related increases in TSH output in response to TRH and consistent responses to repetitive pulses of TRH (5.5 X 10-10 M) during a 4 h period were demonstrated. Studies on the dynamics of thyroid hormone feedback on TRH-stimulated TSH secretion indicated that inhibition was manifest within 1 h and reached a maximum after 2 1/2 h during continual exposure to thyroid hormones. Isobutylmethylxanthine (IBMX) potentiated the effect of raised K+ as well as that of TRH on TSH secretion, suggesting an as yet unidentified relationship between Ca2+ and cyclic AMP.

Animals↗
PubMed1977

Analysis of plasmid deoxyribonucleic acid in a cariogenic strain of Streptococcus faecalis: an approach to identifying genetic determinants on cryptic plasmids.

Streptococcus faecalis strains ND539 and OG1 have been previously shown to be cariogenic in gnotobiotic animals. Deoxyribonucleic acid analyses have revealed the presence of a single 26-megadalton plasmid designated pAM539 in the former strain, whereas the latter strain was found to be plasmid-free. By gene transfer experiments, it was possible to construct isogenic pairs of strains that differed only with regard to the presence or absence of pAM539. Comparative studies of isogenic pairs showed that the presence of pAM539 conferred bacterial sensitivity to a bacteriocin produced by S. faecalis strain 5952.

Animals↗
PubMed1977

Characterization of plasmids determining hemolysin and bacteriocin production in Streptococcus faecalis 5952.

Two plasmids designated pOB1 and pOB2 were isolated from Streptococcus faecalis strain 5952 and found to have molecular weights of approximately 46 X 10(6) and 28 X 10(6), respectively. pOB1 was found to determine hemolytic activity and was transmissible, whereas pOB2 appeared to determine a bacteriocin that is specifically inhibitory to S. faecalis strains harboring the 26-megadalton plasmid pAM539.

Bacteriocins↗
PubMed1976

The development of adrenocorticotrophin-sensitive adenylate cyclase activity in the foetal rabbit adrenal: a correlated biochemical and morphological study.

Proliferation of the smooth endoplasmic reticulum, the site of some hydroxylating steroidogenic enzymes in foetal adrenocortical cells, is the first major change in the process of their differentiation into steroidogenic tissue. This was observed in our ultrastructural studies on foetal rabbit adrenals to begin at about day 19 of development. Morphological changes in the mitochondria, the site of production of other steroidogenic enzymes, occurred at about day 24. The elongated or rod-shaped forms of the earlier stages became flattened and rounded by this time, while the cristae were transformed from a flattened lamellar type of the earlier stages to the tubulo-vesicular form of the adult. Other changes observed included an increase in microvilli and in cell size, with a concomitant increase in thickness of the gland. Adenylate cyclase activity in foetal adrenal homogenates was assessed in response to sodium fluoride (NaF) and ACTH. All preparations responded to NaF. While good responses to ACTH were observed at days 24, 27, 28 and in the neonate, there was a lack of any significant response in the day 19 gland. Foetal ACTH was depressed by administration of cortisol, and the effects of this treatment on both the morphological changes and adenylate cyclase activity was reassessed. The response of foetal adrenals to ACTH was depressed by this treatment and differentiation of the mitochondria was arrested. These results suggest a circumscribed period for the development of ACTH-sensitive adenylate cyclase coinciding with the time at which final differentiation of the mitochondria is completed. Furthermore, both the differentiation of the mitochondria and the development of ACTH-sensitive adenylate cyclase in the foetal adrenal may be dependent on foetal ACTH secretion.

Adenylyl Cyclases↗
PubMed1975

Is "T4 toxicosis" a normal biochemical finding in elderly women?

The lack of equivalence in the distrubtion of normal ranges for free thyroxine index (FT4I) and free triiodothyronine index (FT3I) in the over sixty-five age-group, as compared with the fifteen-sixty-five age-group, supports the idea that "T4 toxicosis" is a common biochemical finding in elderly women. The disparity between FT4I and FT3I ranges was also reflected in the true free T4 and free T3 levels which were measured in some cases. These results suggest that when an increased FT4I is found in an elderly woman with cardiac disease, caution should be exercised in interpreting the result as indicating that thyrotoxicosis is the cause of the cardiac disorder. Estimation of total T3, FT3I, or free T3 seems useful in confirming euthyroidism in such cases.

Adolescent↗