Biomedical subjects

C Huet

Publications and source records attributed to C Huet.

At least 19 recordsLinked to original sources

PubMed2003

Field evaluation of an improved assay using a heat-dissociated p24 antigen for adults mainly infected with HIV-1 CRF02_AG strains in Côte d'Ivoire, West Africa.

The aim of this study was to evaluate the heat-dissociated p24 antigen (HD p24 Ag) assay as an alternative low-cost tool for diagnosis of HIV-1 infection and quantitation of HIV-1 RNA levels in African adults mainly infected with HIV-1 CRF02_AG strains. One hundred seventeen plasma specimens were obtained from HIV-1-seropositive subjects enrolled in the ANRS 1220 PRIMO-CI cohort (Abidjan, Côte d'Ivoire, West Africa). Results of the HD p24 Ag assay were comparable with those of HIV-1 RNA levels quantified in the same antibody-positive plasma samples by the Amplicor HIV-1 Monitor assay (1.5 version; Roche Diagnostics, Indianapolis, IN): sensitivity, 95.7% versus 96.6%, respectively; specificity (evaluated with samples from 75 seronegative subjects), 94.7% versus 100%, respectively. HD p24 Ag and HIV-1 RNA assays were weakly correlated (Spearman coefficient correlation, r = 0.33; P < 0.001) except for HIV-1 RNA levels of >/=5 log10 copies/mL (r = 0.62; P < 0.001). Quantitation of HD p24 antigenemia in 76 plasma specimens from 14 patients treated with highly active antiretroviral therapy demonstrated weaker changes during treatment than those observed with the HIV-1 RNA assay. Follow-up of infected patients using both markers showed different results. The reliability of the HD p24 Ag assay is questionable for clinical and biologic management as a surrogate tool for measurement of HIV-1 RNA levels in Africa.

Adolescent↗

PubMed2002

Uncertainty analysis of the weighted equivalent lung dose per unit exposure to radon progeny in the home.

A parameter uncertainty analysis has been performed to derive the probability distribution of the weighted equivalent dose to lung for an adult (w(lung) H(lung)) per unit exposure to radon progeny in the home. The analysis was performed using the ICRP Publication 66 human respiratory tract model (HRTM) with tissue weighting factor for the lung, w(lung) = 0.12 and the radiation weighting factor for alpha particles, wR = 20. It is assumed that the HRTM is a realistic representation of the physical and biological processes, and that the parameter values are uncertain. The parameter probability distributions used in the analysis were based on a combination of experimental results and expert judgement from several prominent European scientists. The assignment of the probability distributions describing the uncertainty in the values of the assigned fractions (ABB, Abb, AAI) of the tissue weighting factor proved difficult in practice due to lack of quantitative data. Because of this several distributions were considered. The results of the analysis give a mean value of w(lung) H(lung) per unit exposure to radon progeny in the home of 15 mSv per working level month (WLM) for a population. For a given radon gas concentration, the mean value of w(lung) H(lung) per unit exposure is 13 mSv per 200 Bq.m(-3).y of 222Rn. Parameters characterising the distributions of w(lung) H(lung) per unit exposure are given. If the ICRP weighting factors are fixed at their default values (ABB, Abb, AAI = 0.333, 0.333, 0.333; w(lung) = 0.12; and wr = 20) then on the basis of this uncertainty analysis it is extremely unlikely (P approximately 0.0007) that a value of Hw/Pp for exposure in the home is as low as 4 mSv per WLM, the value determined with the epidemiological approach. Even when the uncertainties in the ABB, Abb, AAI, values are included then this probability is predicted to be between 0.01 to 0.08 depending upon the distribution assumed for describing the uncertainties in the ABB, Abb, AAI, values. Thus, it is concluded that the uncertainties in the HRTM parameters considered in this study cannot totally account for the discrepancy between the dosimetric and epidemiological approaches.

Administration, Inhalation↗

PubMed2002

Laminin-alpha6beta1 integrin interaction enhances survival and proliferation and modulates steroidogenesis of ovine granulosa cells.

This study aimed to determine the physiological role of laminin (LN) and its receptor, alpha(6)beta(1) integrin, in controlling the functions of granulosa cells (GC) during follicular development in sheep ovary. Immunohistochemistry experiments showed the presence of increasing levels of LN (P<0.0001), and high levels of mature alpha(6)beta(1) integrin in GC layers of healthy antral follicles during the follicular and the preovulatory phases of the estrous cycle. In vitro, the addition of a function-blocking antibody raised against alpha(6) subunit (anti-alpha(6) IgG) to the medium of ovine GC cultured on LN impaired cell spreading (P<0.0001), decreased the proliferation rate (P<0.05) and increased the apoptosis rate (P<0.05). Furthermore, addition of anti-alpha(6) IgG enhanced estradiol (E2) secretion by GC in the presence or absence of follicle-stimulating hormone (FSH), luteinizing hormone or insulin-like growth factor-I in culture medium (P<0.0001), and inhibited progesterone (P4) secretion in basal conditions or in the presence of low (0.5 ng/ml) FSH concentrations only (P<0.0001). The anti-alpha(6) IgG effect was specific to an interaction of LN with alpha(6)beta(1) integrin since it was ineffective on GC cultured on heat-denatured LN, RGD (arginine-glycine-aspartic acid) peptides and non-coated substratum. Hence, this study established that alpha(6)beta(1) integrin 1) was expressed in GC of antral follicles, 2) mediated the actions of LN on survival, proliferation and steroidogenesis of GC, and 3) was able to dramatically modulate P4 and E2 secretion by GC in vitro. It is suggested that during the follicular and the preovulatory phases of the estrous cycle, the increasing levels of LN in GC of large antral follicles might support their final development to ovulation.

Animals↗

PubMed2002

[Bacillary angiomatosis in an adult infected with HIV-1 at an early stage of immunodepression in Abidjan, Côte d'Ivoire].

Human immunodeficiency virus (HIV)-associated bacillary angiomatosis has rarely been described in Africa. We report here the first case in Côte d'Ivoire. Although in industrialised countries bacillary angiomatosis has been described in patients with low CD4 count, this episode occurred in the first year following HIV-seroconversion in an adult patient with more than 500 CD4 cells per cubic millimetre. Symptoms rapidly and totally disappeared under erythromycin treatment, although with a relapse two years after the end of the first episode. In Africa where people living with HIV often present chronic cutaneous lesions, bacillary angiomatosis may be under-diagnosed. Bacillary angiomatosis must be systematically considered in face of lesions similar to Kaposi's sarcoma. Improving knowledge on symptoms of bacillary angiomatosis in Africa should lead to better treatment and a better estimation of its true frequency which may be underestimated.

AIDS-Related Opportunistic Infections↗

PubMed2001

Size distribution, equilibrium ratio and unattached fraction of radon decay products under typical indoor domestic conditions.

In order to characterise the behaviour of radon decay products under domestic conditions, long-term measurements were carried out from May 1997 to April 1998 in a typical dwelling located in Brittany (France). In particular, the unattached fraction and equilibrium factor were continuously measured. Moreover, the size distributions of unattached and attached radon daughters were investigated by using specific instruments implemented in the laboratory. All these experiments were carried out under different typical aerosol conditions. The results evidenced the strong influence exerted by the characteristics (concentration, size) of ambient aerosol on these different parameters.

Aerosols↗

PubMed2001

Skeletal muscle cell hypertrophy induced by inhibitors of metalloproteases; myostatin as a potential mediator.

Cell growth and differentiation are controlled in many tissues by paracrine factors, which often require proteolytic processing for activation. Metalloproteases of the metzincin family, such as matrix metalloproteases and ADAMs, recently have been shown to be involved in the shedding of growth factors, cytokines, and receptors. In the present study, we show that hydroxamate-based inhibitors of metalloproteases (HIMPs), such as TAPI and BB-3103, increase the fusion of C(2)C(12) myoblasts and provoke myotube hypertrophy. HIMPs did not seem to effect hypertrophy via proteins that have previously been shown to regulate muscle growth in vitro, such as insulin-like growth factor-I, calcineurin, and tumor necrosis factor-alpha. Instead, the proteolytic maturation of myostatin (growth differentiation factor-8) seemed to be reduced in C(2)C(12) cells treated with HIMPs, as suggested by the presence of nonprocessed myostatin precursor only in hypertrophic myotubes. Myostatin is a known negative regulator of skeletal muscle growth, belonging to the transforming growth factor-beta/bone morphogenetic protein superfamily. These results indicate that metalloproteases are involved in the regulation of skeletal muscle growth and differentiation, that the proteolytic maturation of myostatin in C(2)C(12) cells may be directly or indirectly linked to the activity of some unidentified HIMP-sensitive metalloproteases, and that the lack of myostatin processing on HIMP treatment may be a mediator of myotube hypertrophy in this in vitro model.

Blotting, Western↗

PubMed2001

Extracellular matrix regulates ovine granulosa cell survival, proliferation and steroidogenesis: relationships between cell shape and function.

The extracellular matrix (ECM), constituting the follicular basal lamina and present also between follicular cells and in the follicular fluid, is believed to regulate granulosa cell (GC) function during follicular development. Ovine GCs isolated from small (1-3 mm in diameter) or large (4-7 mm in diameter) antral follicles were cultured on various pure ECM components (type I collagen, fibronectin, laminin), synthetic substrata enhancing (RGD peptides) or impairing (poly 2-hydroxyethylmethacrylate (poly-hema)) cell adhesion, or in the presence of heparin. The effects of these factors, used alone or in combination with IGF-I and/or FSH, were evaluated in terms of GC spread, survival, proliferation and steroidogenesis. When grown on type I collagen (CI) gel, poly-hema or heparin, GCs from both large and small follicles exhibited a round shape and a low proliferation rate. Compared with non-coated plastic substratum as a control, these ECM or synthetic compounds enhanced estradiol secretion and reduced progesterone secretion by large-follicle GCs. In contrast, GCs from both large and small follicles spread extensively on CI coating, fibronectin, laminin and RGD peptides. Fibronectin and laminin dramatically increased the proliferation rate and enhanced survival of GCs from both origins. Moreover, fibronectin, laminin and RGD peptides reduced estradiol secretion by large-follicle GCs. Unexpectedly, CI coating increased estradiol secretion and reduced progesterone secretion by large-follicle GCs, suggesting that type I collagen was able to maintain estradiol secretion independently of GC shape. Finally, GC responsiveness to IGF-I and FSH, in terms of proliferation and steroidogenesis, was generally maintained when cells were grown on ECM components, RGD peptides and in the presence of heparin. However, when large-follicle GCs were grown as non-adherent clusters (as observed on poly-hema) basal and IGF-I- and/or FSH-stimulated progesterone secretions were totally abolished. Overall, this study shows that GC shape, survival, proliferation and steroidogenesis can be modulated in vitro by pure ECM components in a specific and coordinated manner. It is suggested that, in vivo, fibronectin and laminin would sustain follicular development by enhancing the survival and proliferation of GCs, whereas type I collagen might participate in the maintenance of estradiol secretion in large antral follicles.

Analysis of Variance↗

PubMed2000

Binding of ADAM12, a marker of skeletal muscle regeneration, to the muscle-specific actin-binding protein, alpha -actinin-2, is required for myoblast fusion.

ADAM12 belongs to the transmembrane metalloprotease ADAM ("a disintegrin and metalloprotease") family. ADAM12 has been implicated in muscle cell differentiation and fusion, but its precise function remains unknown. Here, we show that ADAM12 is dramatically up-regulated in regenerated, newly formed fibers in vivo. In C2C12 cells, ADAM12 is expressed at low levels in undifferentiated myoblasts and is transiently up-regulated at the onset of differentiation when myoblasts fuse into multinucleated myotubes, whereas other ADAMs, such as ADAMs 9, 10, 15, 17, and 19, are expressed at all stages of differentiation. Using the yeast two-hybrid screen, we found that the muscle-specific alpha-actinin-2 strongly binds to the cytoplasmic tail of ADAM12. In vitro binding assays with GST fusion proteins confirmed the specific interaction. The major binding site for alpha-actinin-2 was mapped to a short sequence in the membrane-proximal region of ADAM12 cytoplasmic tail; a second binding site was identified in the membrane-distal region. Co-immunoprecipitation experiments confirm the in vivo association of ADAM12 cytoplasmic domain with alpha-actinin-2. Overexpression of the entire cytosolic ADAM12 tail acted in a dominant negative fashion by inhibiting fusion of C2C12 cells, whereas expression of a cytosolic ADAM12 lacking the major alpha-actinin-2 binding site had no effect on cell fusion. Our results suggest that interaction of ADAM12 with alpha-actinin-2 is important for ADAM12 function.

ADAM Proteins↗

PubMed2000

What should be included in meta-analyses? An exploration of methodological issues using the ISPOT meta-analyses.

OBJECTIVE: To explore the impact of methodologic issues on the results of meta-analyses. The following issues were examined: the type of literature search strategy used; inclusion or exclusion of non-peer-reviewed studies; the inclusion or exclusion of non-English language publications; the effect of trial quality; and the inclusion or exclusion of non-placebo-controlled studies. METHODS: The International Study of Perioperative Transfusion (ISPOT) meta-analyses were used to evaluate each of the methodologic issues. The 10 meta-analyses consisted of technologies to reduce the need for perioperative red blood cell transfusion. The number of trials for each of the meta-analyses varied from 2 to 45. Both EMBASE and MEDLINE searches were conducted, including the use of systematic search strategies. RESULTS: MEDLINE identified the vast majority of trials. Alone, MEDLINE would have missed 8 studies compared to 10 for EMBASE. Use of the systematic search strategies greatly reduced the number of articles to be reviewed compared to open searches. Type of publication, country of study origin, inclusion of non-English publications, and trial quality had very little impact on the estimates of effect. The use of placebo versus open-label control affected the magnitude of the odds ratio for two of the meta-analyses. The results of the two meta-analyses were not statistically significant if only placebo-controlled trials were included. CONCLUSIONS: While methodologic issues had very little impact on the ISPOT meta-analyses, further studies are needed in a variety of other clinical settings. Because MEDLINE, coupled with a review of the references in the identified trials, identified the vast majority of trials, one needs to consider the costs and benefits of searching EMBASE and the pursuance of unpublished and unindexed trials.

Databases, Bibliographic↗

PubMed2000

Regulation of pyc1 encoding pyruvate carboxylase isozyme I by nitrogen sources in Saccharomyces cerevisiae.

In Saccharomyces cerevisiae, the existence of PYC1 and PYC2 encoding cytosolic pyruvate carboxylase isoform I and II is rather puzzling, owing to the lack of potent differential gene regulation by the carbon sources. We report several findings indicating that these two genes are differentially regulated by the nature of the nitrogen source. In wild-type cells, the activity of pyruvate carboxylase, which is the sum of pyruvate carboxylase isoform I and II, was two- to fivefold lower in carbon medium containing aspartate, asparagine, glutamate or glutamine instead of ammonium as the nitrogen source, whereas it was 1.5- to threefold higher when the ammonium source was substituted by arginine, methionine, threonine or leucine. These enzymatic changes were independent of the nature of the carbon source and closely correlated to the changes in beta-galactosidase from PYC1-lacZ gene fusion and in PYC1 transcripts. Transfer of exponentially growing cells of the pyc2 mutant from an aspartate or a glutamate medium to an ammonium medium caused a fivefold increase in PYC1 mRNA in less than 30 min, whereas in the inverse experiment, PYC1 transcripts returned within 30 min to the low levels found in aspartate/glutamate medium. By contrast, these conditions affected neither the pyruvate carboxylase activity encoded by PYC2 nor PYC2 mRNA. Considering that changes in PYC1 expression inversely correlated with changes in alpha-ketoglutarate concentration or in alpha-ketoglutarate/glutamate ratio following the nitrogen shift experiments, and taking into account the pivotal role of this metabolite in ammonium assimilation, it is suggested that changes in alpha-ketoglutarate or in the alpha-ketoglutarate/glutamate ratio might be implicated in triggering the nitrogen effects on PYC1 expression. The physiological significance of the differential sensitivity of PYC1 and PYC2 genes with respect to the nitrogen source in the growth medium is also discussed.

Amino Acids↗

PubMed1999

Technologies to minimize blood transfusion in cardiac and orthopedic surgery. Results of a practice variation survey in nine countries. International Study of Peri-operative Transfusion (ISPOT) Investigators.

OBJECTIVES: Due to the discovery in the 1980s that blood transfusion can transmit HIV, there has been increased interest in technologies that reduce the amount of allogeneic blood used during and after surgery. These technologies include drugs (aprotinin, tranexamic acid, epsilon-aminocaproic acid, erythropoietin), devices (cell salvage), and techniques (acute hemodilution, predeposited autologous donation). The purpose of this study was to ascertain the degree of practice variation, if any, that exists for eight technologies in nine countries in orthopedic and cardiac surgery. METHODS: In each country, either all hospitals or a random sample of hospitals with medical/surgical beds were surveyed between 1995 and 1997. Two instruments were used. The first instrument was a postcard that asked recipients whether the technologies were currently being used in their hospital for orthopedic and/or cardiac surgery to reduce perioperative allogeneic transfusion. The second questionnaire elicited information regarding the degree of use both in qualitative and quantitative terms. Data were collected, entered, and analyzed in each country, with summary results submitted to the Canadian coordinating center on a standardized data collection form. RESULTS: Pharmaceuticals were generally used in a much smaller proportion of hospitals in orthopedic than in cardiac surgery. Aprotinin and tranexamic acid were the drugs most frequently used in cardiac surgery. Nonpharmacological technologies were used to a greater degree than drugs in orthopedic surgery, although there was wide variation among technologies and countries. Acute hemodilution and cell salvage were used in a greater proportion of hospitals for cardiac surgery than orthopedic surgery. CONCLUSIONS: The results of this survey indicate that there is considerable practice variation in the use of technologies to minimize exposure to perioperative allogeneic transfusion within and between countries.

Antifibrinolytic Agents↗

PubMed1998

Chronology of events accompanying follicular atresia in hypophysectomized ewes. Changes in levels of steroidogenic enzymes, connexin 43, insulin-like growth factor II/mannose 6 phosphate receptor, extracellular matrix components, and matrix metalloproteinases.

The chronology of changes in levels of some proteins known to be altered during atresia of ovarian follicles was studied in ewes hypophysectomized at the end of the follicular phase of the estrous cycle. This study was performed by quantitative immunohistochemistry and zymography on large antral follicles (diameter > 3.5 mm) normally destined to ovulate, recovered 24, 36, or 72 h after pituitary ablation. The process of atresia was followed by comparing healthy follicles from intact ewes, with early atretic follicles recovered 24 h after hypophysectomy, clearly atretic follicles recovered 36 h after hypophysectomy, and late atretic follicles recovered 72 h after hypophysectomy. The earliest events of atresia induced by hypophysectomy were detected in theca and consisted of a strong decrease in levels of fibronectin (p < 0.001) and insulin-like growth factor II/mannose 6 phosphate (IGF-II/M6P) receptors (p < 0.05), occurring within the first 24 h following pituitary ablation. In intact animals, similar changes were observed in theca of early atretic follicles, suggesting that these changes may be important events involved in the onset of follicular atresia. In parallel, intrafollicular levels of matrix metalloproteinase-2 and -9 were shown to increase as early as 24 h after hypophysectomy, and a further increase was observed until 72 h after hypophysectomy. These early events were followed by the disappearance of P450 aromatase in granulosa cells 36 h after hypophysectomy (p < 0.05), and a progressive decrease in levels of P450 17alpha-hydroxylase in the theca interna and of gap junction protein connexin-43 in granulosa cells; these markers were still detectable in late atretic follicles 72 h after hypophysectomy. The increase in levels of fibronectin, type IV collagen, laminin, and IGF-II/M6P receptors within granulosa cell layers (p < 0.05) was significant only in late atretic stages, suggesting that these changes may be consequences rather than causes of atresia.

Animals↗

PubMed1997

Changes in extracellular matrix components and steroidogenic enzymes during growth and atresia of antral ovarian follicles in the sheep.

To investigate the involvement of extracellular matrix (ECM) in folliculogenesis in the sheep, parallel changes in ECM components and key steroidogenic enzymes were studied by quantitative immunohistochemistry and immunoblotting during follicular growth and atresia. Growth of ovarian follicles from 1 to 5 mm in diameter was characterized by a progressive increase in P450 cholesterol sidechain cleavage levels in both thecal (p < 0.001) and granulosa cells (p < 0.001), an increase in P450 aromatase levels in granulosa cells of follicles larger than 3.5 mm (p < 0.001), and an increase in levels of P450 17 alpha-hydroxylase C17,20 lyase (P450(17 alpha)) in the theca interna. In addition, during follicular growth, a change in localization of cells expressing P450(17 alpha) within the theca interna was observed, positive cells being sparse within the theca interna of small follicles and specifically located close to the basal laminae in large follicles. In parallel, follicular growth was associated with an increase in levels of type I collagen in granulosa cell layers (p < 0.01) and an increase in levels of fibronectin (p < 0.05), particularly the specific ED-A alternatively spliced variant of fibronectin, in the theca externa. Follicular atresia was characterized by a loss of P450 aromatase in granulosa cells (p < 0.001) and a decrease in levels of P450(17 alpha) in the theca interna (p < 0.05). Simultaneously, levels of fibronectin (p < 0.05), particularly the ED-A variant of fibronectin, decreased in the theca externa of atretic follicles. Within the wall of granulosa cells, levels of fibronectin (p < 0.05), laminin, type IV collagen, and heparan sulfate proteoglycans strongly increased during follicular atresia. Overall, these results show that follicular growth and atresia were associated with distinct changes in levels of ECM components, suggesting that ECM components may play a role in the regulation of proliferation, differentiation, and apoptosis of follicular cells.

Alternative Splicing↗

PubMed1997

Follicular growth and ovarian dynamics in mammals.

General characteristics of female reproductive activity, such as seasonality, cyclicity and triggering of ovulation differ widely among mammals, but common mechanisms underlie ovarian function. In all mammals, follicles begin to grow from a pool of primordial follicles constituted early in life, continuously throughout the life of the female. Follicular development involves two phases. In a first phase (basal follicular growth), follicles grow slowly and follicular growth rate is tightly related to proliferation of granulosa cells. Basal follicular growth is mainly under the control of growth factors of paracrine origin. In these follicles, FSH may exert an indirect mitogenic effect on granulosa cells by enhancing expression of growth factors or growth factor receptors. In a second phase (terminal follicular growth), follicular growth is rapid and occurs by enlargement of the antrum. In addition, it is accompanied by important changes in differentiation of follicular cells. Terminal follicular development is strictly dependent on gonadotrophins. FSH plays determinant roles in enhancing granulosa cell differentiation and survival. These actions are mediated or modulated in an important way by paracrine factors, particularly steroids and growth factors. LH stimulates steroidogenesis in theca cells and sustains terminal maturation of granulosa cells in preovulatory follicles. Follicular growth, atresia and ovulation are accompanied by important tissue remodelling processes, which are under the fine control of proteinases and inhibitors of proteinases. In particular matrix metalloproteinases and their inhibitors are probably involved in the control of rapid terminal follicular growth and regression of atretic follicles as well as in follicular rupture at ovulation.

Animals↗

PubMed1996

Insulin-like growth factor-binding proteins and ovarian folliculogenesis.

In the ovary, insulin-like growth factors (IGFs) enhance both proliferation and differentiation of follicular cells by potentiating gonadotropin's actions. The biological effects of IGFs are strikingly modulated by IGF-binding proteins (IGFBPs), whose levels in follicular fluid dramatically change during folliculogenesis. Indeed, in most mammalian species, follicular growth and atresia are characterized by an increase and a great decrease in the IGFBP-3/IGFBPs < 40 kD (IGFBP-2, -4 and -5) ratio in follicular fluid, respectively. These variations result from both changes in expression of these IGFBPs by follicular cells, and in local degradation by specific intrafollicular proteases. Such changes in IGFBP levels lead to great decrease and increase in IGF bioavailability in atretic and growing healthy follicles, respectively. Hence intrafollicular IGFBPs play a key role in the regulation of follicular development by modulating IGFs and therefore gonadotropin's actions.

Animals↗

PubMed1995

[Bazex paraneoplastic acrokeratosis. Treatment with acitretin].

INTRODUCTION: Bazex paraneoplastic acrokeratosis remains a therapeutic challenge when the cancer cannot be treated. We report the third patient in which a complete clearance of the lesions was obtained with oral acitretine. CASE REPORT: A 67 year-old patient had Bazex paraneoplastic acrokeratosis. Despite a complete cancer screening, no cancer was found. A cervical lymph node metastasis was treated with surgery and radiotherapy. Because the cutaneous lesions got worse after this treatment, the patient received oral acitretine. A complete clearing of the lesions was observed within 2 months. DISCUSSION: Only 2 similar cases have been reported to our knowledge. The comparison with these 2 cases supports the efficacy of oral retinoids in this disease. The search and the treatment of the cancer remain compulsory. CONCLUSION: In some definite cases, oral retinoids can be proposed as a treatment of cutaneous lesions in Bazex paraneoplastic acrokeratosis.

Acitretin↗

PubMed1994

Comparative analysis of neutral endopeptidase (NEP) and villin gene expression during mouse embryogenesis and enterocyte maturation.

Neutral endopeptidase (Endopeptidase 24.11; NEP; neprilysin), an integral membrane protein, and villin, a major microvillar cytoskeletal actin-binding protein, are both typically associated with brush border epithelia. In this study, cRNA probes were hybridized in situ to investigate the expression of NEP and villin genes in embryo and adult mouse enterocytes. During development, villin mRNAs were easily detected in the immature digestive tract well before establishment of the brush border. In 17-day-old embryos, a transient elevation of villin mRNA occurred just prior to a dramatic increase in microvilli length and density. NEP only appeared by day 17 as the embryonic gut began to become functional. It therefore appears that the onset of transcription of specialized cytoskeletal proteins from the brush border preceded that of intrinsic membrane-bound enzyme from microvilli. In the adult intestinal fold, both mRNAs were expressed along the whole length of the villus with maximal expression at its base. In contrast, both proteins were uniformly expressed along the whole crypt-villus axis. Quantitative analysis revealed an asymmetric intracellular distribution of both mRNAs that were differentially polarized in the apical cytoplasm of enterocytes.

Age Factors↗

PubMed1993

Water handling in Caco-2 cells: effects of acidification of the medium.

Caco-2 cells were cultured on permeable supports. At confluence the minute-by-minute net water movement (Jw) was automatically recorded. Simultaneously, unidirectional [14C]mannitol, 22Na+, and/or 36Cl- fluxes and transepithelial resistances were measured. The water and mannitol permeabilities went progressively down between 9 and 16 days after seeding and then stabilized. In this last condition the hydrostatic permeability coefficient (Phydr) was 2.67 +/- 0.31 cm s-1 while the osmotic permeability coefficient (Posm) was 0.0017 +/- 0.0004 cm s-1. Phydr but not Posm was dependent on the temperature and on the presence of Na+ in the medium. A net secretory Jw was observed 16 days after seeding, in the absence of any osmotic, hydrostatic or chemical gradient. This secretory Jw was associated with net Cl- (1.43 +/- 0.43 muequiv h-1 cm-2) and Na+ (1.05 +/- 0.35 muequiv h-1 cm-2) secretions. Amiloride reduced, in open-circuit conditions, both Na+ and Cl- apical to basal fluxes, thus enhancing the net Na+ and Cl- exit. Acidification of the medium (pH 6.2) reversibly increased water and mannitol permeabilities in 10-day-old cultures. In 16-day-old cultures the same shift in medium pH did not change mannitol permeability, while stimulating water secretion. These results, obtained in the absence of supracellular structures (villae, crypts) and subepithelial components (muscular, vascular and conjunctive tissues) indicate that paracellular and transport-associated water pathways are sensitive to changes in the pH of the medium in Caco-2 cell layers.

Adenocarcinoma↗