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Biomedical subjects

D J Hartmann

Publications and source records attributed to D J Hartmann.

At least 55 records · Page 3Linked to original sources
PubMed1992

Interleukin-1 alpha as a potent inhibitor of gonadotropin action in porcine Leydig cells: site(s) of action.

The effects of interleukin on testicular steroidogenesis have been studied in several laboratories, most often by using cultured rat Leydig cells. Several reports have indicated that interleukin-1 beta (IL-1 beta), but not interleukin-1 alpha (IL-1 alpha), exert a potent effect on gonadotropin action in rat Leydig cells. By using cultured porcine Leydig cells as a model, we found that IL-1 alpha (and to a lesser extent IL-1 beta), contrary to previous reports, is a potent inhibitor of LH/hCG steroidogenic action; and we further localized the steroidogenic biochemical step(s) affected by IL-1 alpha. IL-1 alpha inhibited hCG-induced testosterone secretion (about 67%) in a dose- and time-dependent manner. Half maximal and maximal effects were obtained with 4 U/ml (approximately 0.4 ng/ml, 0.3 x 10(-10) M) and 20 U/ml (approximately 2 ng/ml, 1.4 x 10(-10) M) of IL-1 alpha, respectively. The inhibitory effect of IL-1 alpha on gonadotropin action was detected at 6 h and was maximal after 24 h of treatment with the cytokine. The IL-1 alpha inhibitory effect was more potent than that of IL-1 beta: the maximal inhibitory effect of IL-1 beta was obtained with 400 U/ml. Subsequent investigations indicated that IL-1 alpha inhibited different biochemical steps involved in gonadotropin-induced testicular steroidogenesis. In this context, although IL-1 alpha appears to inhibit Leydig cell membrane functions (through a decrease in LH/hCG binding and gonadotropin-induced cAMP production), the antigonadotropin action of the cytokine is probably exerted predominantly at a step(s) located beyond cAMP formation.(ABSTRACT TRUNCATED AT 250 WORDS)

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1992

The role of fibroblasts in dermal vascularization and remodeling of reconstructed human skin after transplantation onto the nude mouse.

The vascularization and the dermal remodeling of two different types of human skin reconstructed "in vitro" and grafted onto the nude mouse were studied. They were composed of human keratinocytes grown either on a human acellular deepidermized dermis (DED), or on a lattice composed of human fibroblasts embedded in bovine type I collagen, a living dermal equivalent (LDE). At different stages after grafting, the transplants were harvested and processed for an immunohistological study with species-specific and non-species-specific antibodies. At one month after grafting, the two types of grafted dermis contained blood vessels whose vascular basement membranes were labeled with a mouse-specific anti-type IV collagen antibody. With an antibody specific for human type IV collagen, a constant labeling of the vascular basement membrane was only observed in the LDE containing fibroblasts. In the DED, a constant association of the mouse endothelial cells with human type IV collagen was observed at early stages after grafting. At later stages, the human type IV collagen progressively disappeared. On the other hand, the dermal-epidermal junction underneath the human epidermis contained human type IV collagen in the two types of reconstructed skin. Labeling with the species-specific antibodies directed against human or murine type I collagen showed that the ratio murine type I collagen versus human type I collagen increased with time, suggesting that the DED is progressively invaded by mouse fibroblasts that produce the mouse collagen. On the other hand, in the LDE, the preexisting bovine type I collagen became progressively undetectable while both human type I collagen and elastic fibers were deposited by numerous human fibroblasts. Mouse type I collagen was not detected. Altogether, these observations made by grafting human skin reconstructed "in vitro" onto the nude mouse should be interesting for evaluating the usefulness of grafting a dermal substrate together with the epidermal sheet in the treatment of burns.

Animals↗
PubMed1992

Serum type I collagen and N-terminal peptide of type III procollagen in patients with alcoholic liver disease: relationship to liver histology.

This study compared, in patients with alcoholic liver disease, the serum concentration of N-terminal peptide of type III procollagen and of a novel serum marker, type I collagen, with liver histological data and assessed the role of these markers in the diagnosis and follow-up of liver changes. Ninety-six patients (mean age 51 years, 61 men and 35 women) were included. All had alcoholic liver disease diagnosed on usual clinical, biochemical, and histological criteria. Two histological scores, one for alcoholic hepatitis and one for fibrosis, were established. Serum N-terminal peptide of type III procollagen and type I collagen were assayed by liquid phase radioimmunoassay. Significant correlations between serum type I collagen and score of fibrosis (r = 0.34, p less than 0.001) and between serum N-terminal peptide of type III procollagen and score of alcoholic hepatitis (r = 0.60, p less than 0.0001) were noted. There was no significant correlation between serum aminotransferases and the score of alcoholic hepatitis. In 25 patients with alcoholic hepatitis reassessed between 3 and 6 months, serum N-terminal peptide of type III procollagen significantly decreased (p less than 0.05) as did the score of alcoholic hepatitis, but serum type I collagen and the score of fibrosis were not modified. These serum markers of collagen metabolism could be useful for the assessment and follow-up in patients with alcoholic liver disease.

Adult↗
PubMed1992

Transforming growth factor beta 1 inhibits gonadotropin action in cultured porcine Sertoli cells.

In the present study, we have tested the effects of transforming growth factor beta 1 (TGF beta 1) on FSH action toward aromatase activity and lactate production in cultured Sertoli cells isolated from immature porcine testes. Whereas treatment of Sertoli cells with FSH resulted in a dose-dependent increase (about 7-fold) in aromatase activity (conversion of testosterone into estradiol) (ED50 = 80 ng/ml FSH), the addition of TGF beta 1 reduced this gonadotropin action. The inhibitory effect of TGF beta 1 on FSH aromatase activity was dose dependent (ED50 = 0.1 ng/ml, 4 pM TGF beta 1) with a maximal decrease (about 40%) observed after a long term (48-h) treatment. TGF beta 1 exerted its inhibitory effect on FSH action at the level(s) of cAMP accumulation, exerting no apparent effect on the gonadotropin receptor or at a site(s) related to cAMP action. TGF beta 1 (2 ng/ml) significantly (P less than 0.002) reduced (52% decrease) FSH-stimulated cAMP levels in cultured porcine Sertoli cells. However, such an inhibitory effect of the growth factor was no longer observed when stimulation of cAMP accumulation with FSH occurred in the presence of methyl isobutyl xanthine (0.5 mM), an inhibitor of cAMP-phosphodiesterase activity. This observation suggests that TGF beta 1 decreased cAMP levels by increasing catabolism of the cyclic nucleotide through an enhancement of cAMP-phosphodiesterase activity. The inhibitory effect of TGF beta 1 was not limited to the action of FSH on aromatase activity but also extended to the gonadotropin action (mediated by cAMP) on lactate production. As for the inhibitory effect of TGF beta 1 on FSH-induced aromatase activity, the inhibitory effect of the growth factor on FSH-stimulated lactate production was dose and time dependent with a maximal decrease (about 30%) observed in the picomolar range (1 ng/ml, 40 pM) after 48 h treatment with TGF beta 1. In conclusion, the present study demonstrates that TGF beta 1 attenuates FSH action on Sertoli cell activity and that such inhibitory action is potentially exerted through a decrease in cAMP levels. Because of the local production of TGF beta 1, it is suggested that the effects of the growth factor reported here might be exerted in the context of the testicular paracrine mechanisms.

1-Methyl-3-isobutylxanthine↗
PubMed1992

Exploration of the relationship between choral singing and successful aging.

This paper describes a retirement village community chorus of 49 with the goal of understanding the place of choral activities in the lives of these older people. Group musical activity provides a link to previous satisfying experiences and serves as a preventive measure against alienation. However, the nature of the activity may be consistent with a willingness to give up some inner directedness. Additional research is recommended since the present design with a comparison group of 49 non-choral members did not allow separation of effects of selection from those of activity.

Adaptation, Psychological↗
PubMed1992

Two-site direct immunoassay specific for active renin.

A sensitive immunoradiometric assay, without an enzymatic step and specific for active human renin, was developed with use of two monoclonal antibodies (MAbs). In this assay system, the first MAb was coupled to magnetic beads (Magnogel); the second one, directed against the active form of the enzyme, was radiolabeled with 125I. The specificity of this assay was demonstrated in experiments measuring the active plasma renin concentration in the presence or absence of inactive renin. The assay, performed in two steps, was sensitive enough to detect 0.9 pg of renin per tube (3.5 ng/L). Intra- or interassay CVs were < 10%. Concentrations of active plasma renin measured in normotensive subjects were between 7 and 40 ng/L.

Adult↗
PubMed1991

Lack of adjuvanticity of human recombinant interleukin-1 beta in collagen induced arthritis in rats.

We investigated the influence of human recombinant interleukin-1 beta (hrIL-1 beta) on the time-course of collagen induced arthritis (CIA) when injected concomitantly with the arthritogenic emulsion. Three sensitizing procedures were compared. The control group received type II collagen only. The other groups differed by the adjunction of demonstrated (MDP) or potential (IL-1 beta) adjuvant. No adjuvant effect of IL-1 was observed as judged on clinical or radiological scores. On the contrary, MDP significantly worsened the lesions of the injected right hindpaw, and increased the incidence of CIA. Surprisingly, humoral response to type II collagen was decreased in the group receiving IL-1 beta. This might be explained by a non specific increase of antigen clearance.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1991

Morphological and immunocytochemical characterization of cultured rat incisor cervical epithelial cells.

Epithelial cells from the cervical loop of the rat incisor were isolated by co-culture of apical explants with growth-arrested 3T3 fibroblasts. The epithelial phenotype of the expanding outgrowths was confirmed 10 days after the seeding of the explants by phase-contrast microscopy and immunocytochemical identification of cytokeratins. After 3 weeks in culture, the epithelial cells covered the entire surface of the coverslips and were then passaged. Subcultures gave rise to a confluent sheet within 10-12 days. Light and electron microscopy showed that confluent cervical epithelial cells generally reconstituted a bi-layered structure similar to Hertwig's epithelial sheath. Epithelial cells from the rat palate, cultured and subcultured according to the same procedure, organized themselves in 5-6 cell layers, the upper cells having generally a squamous morphology. Synthesis of extracellular matrix molecules by rat incisor cervical epithelial cells was studied with specific antibodies. These cells failed to produce type I collagen, but synthesized all the major basement membrane components (type IV collagen, laminin, heparan sulphate proteoglycan and fibronectin). These observations suggest that the culture conditions allowed the reconstitution of a typical Hertwig's epithelial sheath by rat incisor cervical epithelial cells.

Animals↗
PubMed1991

Odontoblast-like cytodifferentiation of human dental pulp cells in vitro in the presence of a calcium hydroxide-containing cement.

The cement produced microcrystals of calcite by reaction with culture medium supplemented with calf serum. Human dental pulp cells seeded on such a substrate preferentially adhered and aggregated around the microcrystals. Immunofluorescence and immunogold labelling revealed a high affinity of serum fibronectin molecules for the calcite crystals. At 4 weeks in culture, the cells had various features of differentiated odontoblasts, notably nuclear polarization, typical appearance of the Golgi apparatus, synthesis of type I collagen and absence of type III, and apical accumulation of actin and vimentin. These cells also elaborated a collagenous extracellular matrix which did not mineralize.

Adolescent↗
PubMed1991

Serum type I collagen and N-terminal peptide of type III procollagen in chronic hepatitis. Relationship to liver histology and conventional liver tests.

The aim of this study was to compare serum N-terminal peptide of type III procollagen to aminotransferases and gamma-globulins as a marker for histological activity in patients with chronic hepatitis and to assess the role of type I collagen, a new serum marker, as a marker of fibrosis in these patients. Sixty patients with biopsy-proven chronic hepatitis were included in this study. Liver disease was virus B-related in 29, autoimmune in five, drug-induced in five, and of unknown etiology in 21. Each biopsy was independently assessed by two liver pathologists. Two histological scores, a score of activity and a score of fibrosis, were established. Serum N-terminal peptide of type III procollagen and type I collagen were assayed by liquid phase RIA. Significant correlations were noted between serum N-terminal peptide of type III procollagen and scores of activity (r = 0.70, p less than 10(-4)) and fibrosis (r = 0.45, p = 0.0005), and between serum type I collagen and scores of activity (r = 0.46, p = 0.0004) and fibrosis (r = 0.67, p less than 10(-4)). When the correlation between scores of activity and fibrosis (r = 0.52, p = 10(-4)) was considered by partial correlation, serum N-terminal peptide of type III procollagen was correlated with the score of activity (r = 0.63, p less than 10(-3)) but not with the score of fibrosis, and serum type I collagen was correlated with the score of fibrosis (r = 0.58, p less than 10(-3)), but not with the score of activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

A state-wide assessment: marital stability and client outcomes.

This paper presents results of Missouri's first statewide evaluation of alcohol and drug treatment programs. The study utilized a 1-year follow-up sample of 242 respondents to explore the nature and patterns of post-treatment functioning. This paper focuses on the impact of client marital stability on post-treatment substance use. The data supported the expected result that marital status was related to post-treatment relapse. Further analysis suggests that transitional periods between marriage and divorce are especially important in understanding the pattern of relapse after treatment. Multivariate analysis indicates that the marital status effect is important both directly and in interaction with program completion. The data suggest that attention to transitional states and interpersonal functioning should be incorporated into client follow-up.

Adolescent↗
PubMed1991

Modulation of human dermal fibroblast extracellular matrix metabolism by the lymphokine leukoregulin.

The effect of leukoregulin, a 50-kD lymphokine with unique antitumor properties, was studied in vitro on several fibroblast functions. Leukoregulin did not inhibit fibroblast proliferation, as measured by cell enumeration and [3H]thymidine incorporation, and had no cytotoxic effect in terms of increased membrane permeability detected by trypan blue exclusion, two of the major leukoregulin actions on tumor cells. Leukoregulin induced a dose-dependent decrease in collagen synthesis, demonstrated by decreased [3H]proline incorporation into collagenase-digestible protein, as early as 6 h after the addition of the lymphokine to human fibroblasts. Leukoregulin inhibited the synthesis of both type I and type III collagen, as measured by SDS-PAGE and by specific radioimmunoassay. Neutralizing antibodies to interleukin-1 alpha, interleukin-1 beta, tumor necrosis factor-alpha, and interferon-gamma failed to alter the effect of leukoregulin on collagen synthesis, attesting that leukoregulin action was not due to contamination by these cytokines. Inhibition of collagen synthesis occurred concomitantly with increased secretion of prostaglandin E2 and a transient rise in intracellular cyclic AMP content, peaking at 6 h. However, blocking prostaglandin synthesis with indomethacin did not counteract inhibition of collagen synthesis by leukoregulin, demonstrating independence of this action of leukoregulin from cyclooxygenase metabolites. Leukoregulin also stimulated glycosaminoglycan production in a dose-dependent manner, affecting the synthesis of hyaluronic acid as the major fibroblast-derived extracellular glycosaminoglycan. In addition, secretion of neutral proteases (collagenase, elastase, caseinase) was increased. These observations indicate that leukoregulin is able to regulate synthesis of molecules critical to the deposition of the extracellular matrix by nontransformed nonmalignant fibroblasts.

Antineoplastic Agents↗
PubMed1991

Comparative effects of interleukin-1 and tumor necrosis factor-alpha on collagen production and corresponding procollagen mRNA levels in human dermal fibroblasts.

The effects of recombinant human Interleukin-1 alpha (IL-1 alpha), Interleukin-1 beta (IL-1 beta), and Tumor Necrosis Factor-alpha (TNF-alpha) on collagen biosynthesis were studied in vitro using dermal fibroblast cultures. Both forms of IL-1 and TNF-alpha induced a dose-dependent inhibition of both types I and III collagen synthesis, as measured by radioimmunoassay, gel electrophoresis, or collagenase-sensitive material. This effect was accompanied by a significant release of prostaglandin E2 into the culture medium. However, indomethacin, a potent inhibitor of prostaglandin synthesis, could not prevent the inhibitory effect of the three cytokines on collagen synthesis. Measurement of type I and type III procollagen mRNA levels in IL-1 treated cells revealed that both IL-1 alpha and IL-1 beta were potent enhancers of procollagen gene expression at pretranslational level. On the other hand, TNF-alpha was found to reduce the steady-state levels of type I and III procollagen mRNA in a dose-dependent manner. Quantitation of IL-1 beta and TNF-alpha transcripts following TNF-alpha treatment of fibroblasts indicated that this cytokine can induce IL-1 beta gene expression in these cells. By contrast, TNF-alpha mRNA remained at a constant level after TNF-alpha exposure. These data suggest that IL-1 and TNF-alpha, two cytokines that share several biologic activities, modulate collagen deposition in dermal fibroblasts by mechanisms that are clearly different: TNF-alpha appears to act at a transcriptional level to inhibit collagen synthesis, whereas IL-1 inhibitory action involves important translational regulation, still unknown, that counterbalances its stimulatory effect on procollagen mRNA levels. Moreover, our data suggest the existence of local fibroblastic cytokine production that may be involved in the modulation of extracellular matrix deposition.

Adult↗
PubMed1991

Changes in the elastic tissue of the non-sun-exposed skin of cigarette smokers.

Biopsies were taken from the upper and inner arm of 10 60-year-old male cigarette smokers and compared with 10 age-matched controls who were non-smokers. The mean relative area, number and thickness of the elastic fibres were significantly increased in the cigarette smokers compared to the controls. These results were confirmed using antibodies to elastin or the microfibrillar component of elastic tissue. In the smokers the broader and more fragmented elastic fibres in the skin were not as intensely stained as those of the non-smokers and the ultrastructural alterations of the elastic fibres were similar to those in solar elastosis.

Antibodies↗
PubMed1991

Tumor necrosis factor alpha inhibits gonadotropin action in cultured porcine Leydig cells: site(s) of action.

In the present study, we have tested the direct effects of tumor necrosis factor-alpha (TNF-alpha) on basal and human (h)CG-stimulated testosterone secretion by cultured purified Leydig cells isolated from immature porcine testes. TNF-alpha reduced (as much as 90% decrease) hCG-stimulated, but not basal testosterone secretion in a dose- and time-dependent manner. The maximal and half-maximal effects were, respectively, 3.75 ng/ml (2.2 x 10(-10) M) and 0.66 ng/ml (3.9 x 10(-11) M) of TNF-alpha after 48 h treatment. TNF-alpha antagonizes the gonadotropin hormonal action by affecting at least two types of biochemical steps. First, TNF-alpha reduced LH/hCG binding to a maximal decrease of 45% obtained with 2 ng/ml of TNF-alpha after 48 h of treatment. TNF-alpha also inhibited (44% decrease) hCG-stimulated cAMP production in optimal conditions (20 ng/ml, 72 h). Second, TNF-alpha significantly (P less than 0.001) reduced testosterone secretion stimulated with 8-bromo-cAMP (3 x 10(-3) M) in a similar range (86% decrease) to that observed with the gonadotropin. Such an observation indicates that the antigonadotropic action of the cytokine is exerted in a predominant manner at a step(s) located beyond cAMP formation. Furthermore, incubation of Leydig cells with 22R-hydroxycholesterol (5 micrograms/ml, 2 h) reversed most of the inhibitory effect of TNF-alpha on androgen production. Indeed, the TNF-alpha (20 ng/ml, 72 h) inhibitory effect on testosterone production was limited to about 20% (P less than 0.03) in Leydig cells supplied with 22R-hydroxycholesterol. Such a moderate effect of the cytokine in the presence of 22R-hydroxycholesterol compared with that observed when androgen secretion was stimulated with the gonadotropin (up to 90% inhibition) indicate that TNF-alpha acts by dramatically reducing cholesterol substrate availability in the mitochondria. Such an effect of TNF-alpha is directly exerted on Leydig cells since TNF-alpha receptors (dissociation constant approximately 5.4 x 10(-10) M) are present in primary cultures of purified porcine Leydig cells. Together, the present findings show that in Leydig cells TNF-alpha antagonizes the gonadotropin action on testosterone formation predominantly through a decrease in the availability of cholesterol substrate in the mitochondria.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1991

Aminoterminal propeptide of type III procollagen: a marker of disease activity in schistosomal patients.

The serum concentration of aminoterminal propeptide of type III procollagen was measured in 44 Egyptian healthy controls and 29 patients with hepatosplenomegaly originating from endemic areas for schistosomiasis in Egypt. Patients were classified into two main groups according to the histopathological pattern of the liver biopsy: patients with active schistosomal liver fibrosis and patients with inactive schistosomal liver fibrosis. Serum aminoterminal propeptide of type III procollagen levels were elevated in most of patients with active fibrosis but not in those with inactive schistosomiasis. From the present work, it is suggested that aminoterminal propeptide of type III procollagen can be used as a marker for active fibrogenesis in patients with schistosomal liver fibrosis.

Adolescent↗
PubMed1991

Isolation and characterization of rat alveolar bone cells.

Samples of rat alveolar bone were first treated by collagenase digestion and then used as explants for cell culture. The cells obtained were subcultured and characterized by morphological and functional criteria. Their alkaline phosphatase activity was increased after incubation in 1,25-(OH)2 vitD3 10(-8) M whereas with gingival cells it did not change. The bone derived-cells organized nodular structures, synthesized type I collagen, Gla-protein, few type III collagen, and fibronectin. In the defined culture conditions no mineralization was observed. However, the method used allows to obtain cells from rat alveolar bone displaying some features of the osteoblastic phenotype.

Alveolar Process↗