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Biomedical subjects

C Mendelson

Publications and source records attributed to C Mendelson.

10 recordsLinked to original sources
PubMed1995

Community empowerment in rural health care.

The Healthy Communities 2000 mandate calls for public health leaders to involve community members in setting health priorities and implementing programs in response to the national health objectives for the year 2000 (American Public Health Association, 1991). This paper describes community involvement through a community empowerment nursing intervention and evaluates its application in a rural community. A community health nursing project (AHCPR, Grant No. HS06801) with three interventions, one of which was community empowerment, was designed to address the health needs of small, rural, underserved, primarily Mexican American communities in Arizona. Community empowerment in this project was based on the community-development approach to community organization, and involved community health nurses and lay health workers, called promotoras, who are key persons in community development. The implementation of two health fairs, one the result of the community-empowerment intervention, is described and evaluated in relation to community health. The community-empowerment intervention was based on community participation and responsibility, hallmarks of the second health fair, reflecting lay expertise and cooperation among various levels of the community. Successes and limitations of the health fairs provide feedback for developing a community-empowerment intervention.

Arizona↗
PubMed1994

Effect of interstitial lung disease macrophages on T-cell signal transduction.

Some types of interstitial lung disease (ILD) are characterized by an abnormal proliferation and activation of lymphocytes in the alveolus and interstitium. Recent data have suggested that membrane signals on alveolar macrophages (AM) in normal lung play a crucial role in limiting lymphocyte activation by altering early events in receptor-mediated signal transduction in lymphocytes. In the current study fixed AM from normal volunteers and from patients with either sarcoidosis or idiopathic pulmonary fibrosis were compared for the ability to inhibit CD3-mediated increases in intracellular calcium concentration [(Ca2+)i]. All normal AM inhibited CD3-mediated increases in (Ca2+)i, whereas seven of 10 ILD AM were permissive of this early event in T-lymphocyte activation. Patients with ILD and permissive AM displayed significantly greater mean BAL lymphocytes than did those with suppressive AM (42 versus 12%, respectively). The inhibitory effect of normal AM could be partially duplicated by incubation of lymphocytes with surfactant (SF) obtained from normal lungs. Analysis of one SF component, SF protein A, in normal and in ILD AM membranes disclosed reduced SF protein A in ILD AM. These results demonstrate alterations in AM in patients with ILD and a lymphocytic alveolitis that renders AM permissive for early events in T-cell activation.

Biopsy↗
PubMed1991

Regulation of expression of the genes encoding steroidogenic enzymes.

In recent years it has become apparent that tropic hormones involved in steroidogenesis act to regulate the expression of the enzymes involved in the various steroidogenic pathways. This is particularly evident in the ovary where the episodic secretion of steroids throughout the ovarian cycle is regulated largely by changes in the levels of the particular enzymes involved in each step of the steroid biosynthetic pathways. Recently, the genes for the various cytochrome P450 species involved in ovarian steroidogenesis, namely cholesterol side-chain cleavage P450 (P450SCC), 17 alpha-hydroxylase P450 (P450(17 alpha], and aromatase cytochrome P450 (P450AROM) have been isolated and characterized, making it possible to study the regulation of expression at the molecular level. To this end, a series of chimeric constructs have been prepared in which fragments of the 5'-untranslated region of bovine P450(17 alpha) and P450SCC have been inserted upstream of the chloramphenicol acetyl transferase (CAT) and beta-globin reporter genes. These constructs have been used to transfect primary cultures of bovine luteal and thecal cells. The results indicate that cAMP responsiveness lies within defined regions of genes which do not contain a classical CRE, similar to previous results utilizing adrenal cells in culture. Furthermore, although constructs containing both the P450(17 alpha) and P450SCC 5'-upstream regions are expressed in both luteal and thecal cell cultures, only those containing the P450SCC sequences are expressed in luteal cells. Studies on the expression of P450AROM indicate that the promoter which is responsible for its expression in human placenta is not operative in the corpus luteum. Thus estrogen biosynthesis may be regulated by the differential use of tissue specific promoters, thus accounting for the complexity and multifactorial nature of the expression of this activity.

Animals↗
PubMed1975

Dependence of gonadotropin-induced steroidogenesis upon RNA and protein synthesis in the interstitial cells of the rat testis.

The effects of inhibitors of RNA and protein synthesis upon gonadotropic stimulation of testosterone and cyclic AMP production by the Leydig cellwere investigated in vitro with enzyme-dispersed interstitial cells of the rat testis. The testosterone response to human chorionic gonadotropin was abolished by cycloheximide and puromycin, and was markedly reduced by actinomycin D and cordycepin. During 3-h time studies, cycloheximide caused complete inhibition of subsequent steroid production when added at times up to 90 min after the commencement of incubation with human chorionic gonadotropin. Actinomycin D did not completely abolish the testosterone response when added at zero time, and became progressively less effective when added at later times during the incubation period. The stimulation of steroidogenesis by dibutyryl cyclic AMP was also completely abolished by cycloheximide and puromycin, and was significantly reduced by acinomycin D and cordycepin. By contrast with the marked inhibition of steroid production by cycloheximide and actinomycin D, the formation of cyclic AMP during human chorionic gonadotropin stimulation was relatively unaffected by either inhibitor. These results indicate that the stimulation of testosterone production by the Leydig cell in response to gonadotropins and dibutyryl cyclic AMP is dependent upon the synthesis of new RNA and protein moleucles. Thus, effects of gonadotropin and cyclic AMP upon both transcriptional and translational processes appear to be essential intermediate steps in the activation of testicular steroidogenesis. The rapid and complete abolition of subsequent steroid synthesis following addition of cycloheximide or puromycin to human chorionic gonadotropin-stimulated interstitial cells suggests that a relatively labile protein is formed during gonadotropin action.

Animals↗
PubMed1975

Gonadotropin binding and stimulation of cyclic adenosine 3':5'-monophosphate and testosterone production in isolated Leydig cells.

Gonadotropin binding and stimulation of cyclic adenosine 3':5'-monophosphate (cyclic AMP) formation and testosterone synthesis were studied in collagenase-dispersed interstitial cells from the adult rat testis. Binding of 125I-human chorionic gonadotropin (hCG) by isolated Leydig cells was of high affinity (Ka = 10(10) M-1) and low capacity, equivalent to approximately 6000 sites/cell. The binding data were consistent with the presence of a single order of receptors, with no interaction between binding sites. Stimulation of testosterone synthesis by increasing concentrations of hCG was completely dissociated from changes in cyclic AMP formation, and maximum activation of steroidogenesis was induced by hCG concentrations which had no effect upon cyclic AMP production. Kinetic analysis of gonadotropin-induced responses in dispersed Leydig cells also showed a marked dissociation between steroidogenesis and cyclic nucleotide formation. Low concentrations of hCG caused maximum stimulation of testosterone production which was not accompanied by a rise in cyclic AMP formation at any time after addition of gonadotropin. Higher concentrations of hCG caused marked elevations of cyclic AMP at progressively earlier time intervals, but did not alter the 20 to 30 min lag period required for induction of testosterone synthesis. These observations indicated that occupancy of gonadotropin receptors occurs over a much wider range of hCG concentration than that required for maximum steroidogenesis.

Animals↗