Biomedical subjects

D Ménard

Publications and source records attributed to D Ménard.

At least 19 recordsLinked to original sources

PubMed2006

Exciton formation and annihilation during 1D impact excitation of carbon nanotubes.

Near-infrared electroluminescence was recorded from unipolar single-wall carbon nanotube field-effect transistors at high drain-source voltages. High resolution spectra reveal resonant light emission originating from the radiative relaxation of excitons rather than heat dissipation. The electroluminescence is induced by only one carrier type and ascribed to 1D impact excitation. An emission quenching is also observed at high field and attributed to an exciton-exciton annihilation process and free carrier generation. The excitons' binding energy in the order of 270 meV for 1.4 nm SWNTs is inferred from the spectral features.

Journal Article↗

PubMed2005

Efficacy of chloroquine-proguanil malaria prophylaxis in a non-immune population in Bangui, Central African Republic: a case-control study.

A case-control study was conducted to evaluate the efficacy of the combination of chloroquine plus proguanil as malaria prophylaxis in a non-immune population living in the Central African Republic. Cases were patients presenting with a malaria attack confirmed by a positive blood film and/or an HRP2 positive antigen test at the Pasteur Institute of Bangui. Two control subjects were included per case: one was a relative or close friend and the other was matched to the patient with respect to the length of stay. A questionnaire assessing malaria prophylaxis habits and malarial risk factors over the 2-month period prior to inclusion in the study was given to 48 cases and 96 controls. A conditional logistic regression was used to identify risk factors. The efficacy of the chloroquine plus proguanil regimen was found to be high (95.5%, 95% CI 74.0-99.2%) in this country known for high chloroquine resistance. Our data lend some support to the use of chloroquine plus proguanil in Bangui, and the protective efficacy of chloroquine plus proguanil should now be studied prospectively as part of a randomised controlled trial of various prophylactic drugs.

Adolescent↗

PubMed2001

The polymorphism at codon 54 of the FABP2 gene increases fat absorption in human intestinal explants.

Based on titration microcalorimetry and Caco-2 cell line transfection studies, it has been suggested that the A54T of the FABP2 gene plays a significant role in the assimilation of dietary fatty acids. However, reports were divergent with regard to the in vivo interaction between this polymorphism and postprandial lipemia. We therefore determined the influence of this intestinal fatty acid-binding protein polymorphism on intestinal fat transport using the human jejunal organ culture model, thus avoiding the interference of various circulating factors capable of metabolizing in vivo postprandial lipids. Analysis of DNA samples from 32 fetal intestines revealed 22 homozygotes for the wild-type Ala-54/Ala-54 genotype (0.83) and 10 heterozygotes for the polymorphic Thr-54/Ala-54 genotype (0.17). The Thr-encoding allele was associated with increased secretion of newly esterified triglycerides, augmented de novo apolipoprotein B synthesis, and elevated chylomicron output. On the other hand, no alterations were found in very low density lipoprotein and high density lipoprotein production, apolipoprotein A-I biogenesis, or microsomal triglyceride transfer protein mass and activity. Similarly, the alanine to threonine substitution at residue 54 did not result in changes in brush border hydrolytic activities (sucrase, glucoamylase, lactase, and alkaline phosphatase) or in glucose uptake or oxidation. Our data clearly document that the A54T polymorphism of FABP2 specifically influences small intestinal lipid absorption without modifying glucose uptake or metabolism. It is proposed that, in the absence of confounding factors such as environmental and genetic variables, the FABP2 polymorphism has an important effect on postprandial lipids in vivo, potentially influencing plasma levels of lipids and atherogenesis.

Absorption↗

PubMed2001

Gastric cancer cell lines as models to study human digestive functions.

The present investigation aims at defining the functional status of several gastric cancer cell lines in order to assess their usefulness as adequate cellular models to study the regulation of gastric digestive functions. Compared to AGS, Hs746t and KATO-III cells, NCI-N87 exhibited an unique differentiation status. They formed coherent monolayers expressing E-cadherin and ZO-1 junctional proteins; their integrity and epithelial morphology were maintained at post-confluency for up to 10 days. All cell lines synthesized PAS-reactive (mucous-type) glycoconjugates. However, only NCI-N87 cells expressed MUC6 glycoprotein suggesting a mucopeptic phenotype. Immunostaining, enzymatic assays, Western blotting and Reverse Transcriptase polymerase chain reaction (RT-PCR) revealed that all cell lines contained varying levels of pepsinogen (Pg5) and human gastric lipase (HGL). Only NCI-N87 cells were able to express zymogens at higher levels, in granule-like structures, and to efficiently secrete both HGL and Pg5. The addition of epidermal growth factor (EGF) to post-confluent NCI-N87 cells, which exhibit an abundant membrane staining for EGF-receptors, modulated HGL activity without affecting Pg5. In conclusion, this investigation enlightens the potential usefulness of the gastric cell line NCI-N87 as a model for elucidating the cellular and molecular mechanisms involved in the regulation of human gastric epithelial functions.

Blotting, Western↗

PubMed2001

Expression of CYP27A, a gene encoding a vitamin D-25 hydroxylase in human liver and kidney.

Vitamin D3 (D3) is not active but must be hydroxylated at C-25 in liver before acquiring its hormonal potential in the kidney. The sterol-27 hydroxylase (gene symbol: CYP27A) catalyses the oxidation of sterol side chain in bile acid synthesis but the enzyme is also known as a D3-25 hydroxylase. The study examined the expression of the gene encoding CYP27A in adult and fetal human livers and kidneys. Thirty-nine adults (18 men and 21 women; mean age 58 years in men and 57 years in women) and three normal fetuses gestational age 17-19 weeks were studied. Tissue CYP27A mRNA and serum 25OHD concentrations were measured. Normal specimens: CYP27A transcript was found to be higher in adult than in fetal livers but its expression was similar in adult and fetal kidneys. In fetuses, no difference was observed between CYP27A levels in livers and kidneys. In adult livers CYP27A levels were higher in women than in men. Hepatic CYP27A mRNA and serum 25OHD concentrations were both found to be higher in summer than in winter. Multiple linear regression analyses indicate that the season of the year and the serum 25OHD concentrations (but not 1,25(OH)2D concentrations) are the best predictors of CYP27A mRNA abundance in normal adult livers. In situ hybridization illustrates a clear label in hepatocytes which increases in intensity in the perivenous region of the hepatic acinus. Pathological specimens: In one man with an hepatic carcinoma there was a very large increase in CYP27A (> 1000 fold) compared to the level found in the normal liver. In that patient, serum 25OHD concentrations were found to be high considering the level of CYP27A mRNA in the normal hepatic area suggesting that the neoplastic tissue contributed to the C-25 hydroxylation of vitamin D. Specimens obtained from two patients suffering from focal hepatic hyperplasia indicate that in one case the level of CYP27A mRNA was twice as high in the pathological than in the normal area while in the other its levels were similar in both areas. No difference in the CYP27A transcript was observed between specimens obtained from normal areas and those obtained form either an hepatic adenoma or from two intrahepatic colonic metastases. CYP27A is present not only in the human adult liver but also in the adult kidney, and in the fetal liver and kidney. Our findings illustrate that CYP27A can be significantly upregulated in certain pathological situations such as in hepatic carcinoma and that the neoplastic tissue could contribute to the circulating concentration of 25OHD.

Adenoma↗

PubMed2001

Immunolocalization, ontogeny, and regulation of microsomal triglyceride transfer protein in human fetal intestine.

To examine the multiple stages of lipoprotein packaging during development, we studied localization, ontogeny, and regulation of microsomal transfer protein (MTP), a crucial protein for lipid transport. With the use of immunofluorescence, MTP was identified in villus and crypt epithelial cells in different regions of human fetal intestine, including colon. Staining was detected as early as the 13th wk of gestation in all gut segments and was almost entirely confined to the columnar epithelial cells of the jejunum and colon. Unlike immunofluorescence, which provides qualitative but not quantitative information on MTP signal, enzymatic assays revealed a decreasing gradient from proximal small intestine to distal, as confirmed by immunoblot. Activity of MTP in small intestinal explants cultured for different incubation periods (0, 4, 8, and 24 h) peaked at 4 h but remained insensitive to different concentrations of oleic acid. Also, a trend toward increasing MTP activity was observed at 20-22 wk of gestation. Finally, in strong contrast to jejunal efficiency, colonic explants displayed impaired lipid production, apolipoprotein biogenesis, and lipoprotein assembly, in association with poor expression of MTP. These findings provide the first evidence that human fetal gut is able to express MTP and emphasize the distinct regional distribution, regulation by oleic acid, and ontogeny of MTP.

Adult↗

PubMed2001

Coordinated control of fetal gastric epithelial functions by insulin-like growth factors and their binding proteins.

The influence of insulin-like growth factors (IGFs) and their binding proteins (IGFBPs) on human gastric functions are unknown. This study was undertaken to evaluate the ability of fetal gastric mucosa to produce IGFBPs and to test the effects of IGF-I, IGF-II, and synthetic truncated IGFs that do not interact with IGFBPs on epithelial cell proliferation and glandular zymogenic function. Western blots, Far Western blots, and immunohistochemistry were performed to characterize the expression of IGFBP-1 to -6 and IGF-I receptor. The effects of growth factors on DNA synthesis and lipase and pepsin activities were determined in gastric explants maintained in serum-free organ culture. All gastric epithelial cells expressed the IGF-I receptor. IGFBP-2 to -6 were produced endogenously, and they were differentially localized along the foveolus-gland axis and modulated in culture. Exogenous IGF-I and IGF-II were able to reduce lipase activity without affecting pepsin, whereas they exerted different effects on cellular proliferation: IGF-I was stimulatory and IGF-II had no influence. Illustrating the complex regulatory effect that IGFBPs exert on IGF bioactivity, both truncated IGF-I and IGF-II stimulated DNA synthesis more than IGF-I. Moreover, the striking difference in mitogenic activity between truncated and native forms of IGF-II probably reflects the abundance of IGFBP-2 and IGFBP-6, two IGF-II carriers, in the foveolus/neck region, including the proliferative compartment. This study provides new evidence for the involvement of an intragastric IGF/IGFBP system in the fine regulation of epithelial cell division and also in the control of zymogen synthesis. Moreover, the specific influence of IGF-II as a mitogen appears to be tightly regulated by IGFBP isoforms preferentially associated with this growth factor and proliferative cells.

Blotting, Western↗

PubMed2001

[Toxoplasmosis, rubella, syphilis, hepatitis B and HIV infection in women being followed for pregnancy in a population on the east coast of New Caledonia ].

In view of the sparse available data concerning the main infectious illnesses screened for during pregnancy (toxoplasmosis, rubella, syphilis, hepatitis B virus and HIV) in the Northern Province and generally throughout New Caledonia, we decided to undertake a retrospective study based on the files of pregnant women having consulted between September 1996 and September 1999 in the East-Coast provincial hospital (New-Caledonia). First, we wished to estimate the prevalence of toxoplasmosis, rubella, syphilis, hepatitis B virus and HIV Second, we wished to specify the main characteristics of these pregnant women, to trace the evolution of seroprevalence over the study time period and consider the influence of various factors such as age, place of residence and professional occupation. The biological study of these pregnancies was hindered by the fact that approximately half of women consult only from the second trimester of their pregnancy. This result underlines the importance of emphasising efforts aiming to bring women to consult earlier and of improving the regularity and also the interpretation of serological tests (especially for toxoplasmosis serology). Within this population, we found the following percentages of seroprevalence: for toxoplasmosis between 83.6% and 89.6% (zone of hyperendemla), for rubella between 91.6% and 95.8%, for syphilis between 7% and 12.4%, for hepatitis B virus between 61.8% and 76% (for women immune to hepatitis B, the frequency of acquisition of immunity by viral infection was understood between 64.3% and 80.3%) and for HIV 0%. The hepatitis B surface antigen (HbsAg) carrier rate was estimated between 1.7% and 4.9%. Following and informing pregnant women of the risk of toxoplasmosis appears to be of key importance as well as screening HbsAg carriers in order to limit viral transmission to the foetus.

Female↗

PubMed2000

Neuropeptide FF attenuates allodynia in models of chronic inflammation and neuropathy following intrathecal or intracerebroventricular administration.

Experiments were conducted to explore the effects of Neuropeptide FF acting at spinal and supraspinal sites in models of chronic inflammatory or neuropathic pain and of acute pain. Neuropeptide FF was administered intrathecally (i.t.; 10.0, 25.0 and 50.0 nmol) or intracerebroventricularly (i.c.v.; 10.0, 12.5 and 15.0 nmol) either 24 h after inflammation-inducing injections of Freund's Complete Adjuvant in one hind paw or 7 days after unilateral sciatic nerve constriction. Evoked pain was assessed by measuring the withdrawal response threshold (in grams of pressure) to a mechanical stimulus applied to the plantar surface of the injured paw. Neuropeptide FF dose-dependently attenuated the allodynic response (i.e., withdrawal from a normally innocuous stimulus) to mechanical stimulation in the inflammatory and neuropathic model following i.t. (ED50=20.86 nmol and ED50=18.91 nmol, respectively) and i.c.v. (ED50=12.31 nmol and ED50=11.68 nmol, respectively) administration. Pretreatment with naloxone (2.0 mg/kg; s.c.) attenuated the anti-allodynic effect of i.t. or i.c.v. Neuropeptide FF in rats experiencing inflammatory, but not neuropathic pain. In contrast, Neuropeptide FF administered i.t. (10.0, 25.0 and 50.0 nmol) or i.c.v. (10.0, 12.5 and 15.0 nmol) had no effect on the response to acute thermal or mechanical stimulation. Neuropeptide FF injected i.t. or i.c.v. in inflamed or neuropathic rats did not produce any sign of motor dysfunction. These results suggest that Neuropeptide FF acting at spinal and supraspinal sites plays a role in modulating chronic, but not acute pain. Furthermore, the results suggest that the anti-allodynic effect of Neuropeptide FF is mediated indirectly by naloxone-sensitive opioid mechanisms in rats subjected to inflammatory, but not neuropathic pain.

Animals↗

PubMed2000

Developmental aspects of lipid and lipoprotein synthesis and secretion in human gut.

This review article focuses on the ontogeny and the regulatory mechanisms involved in the modulation of the intracellular events governing the assembly and delivery of lipoproteins in human gut. The human fetal intestine organizes villi covered with well-differentiated enterocytes during the end of the first trimester in utero. One striking event is the formation of villi in the colonic mucosa similar to those of the small intestine. The small intestine exhibits very early (14-20 weeks) the capacity to absorb lipids, to elaborate most of the major lipoprotein classes (chylomicrons, very-low-density lipoproteins, low-density lipoproteins, high-density lipoproteins), and to efficiently export these lipoproteins from the intestinal cells. The ontogenic changes of lipid and lipoprotein synthesis are correlated with specific patterns of regulatory enzymes (HMG-CoA reductase, ACAT, MGAT) that are representative of key patterns such as the cholesterol pathway, cholesterol esterification, and neutral lipid pathway. The human fetal colon also has the capability to synthesize lipids, lipoproteins, and apolipoproteins. However, comapred with the small intestine, it is much less efficient at exporting these lipoproteins. Epidermal growth factor, insulin, and hydrocortisone, which are known modulators of the brush border digestive functions of the human gut, differentially modulate the synthesis and secretion of lipoproteins in the small intestine and colon. The use of human fetal gut represents a unique model to further our understanding of the complex biosynthetic molecular events essential for the formation and secretion of lipoproteins relevant to human intestine, both in normal or pathological conditions.

Animals↗

PubMed2000

Establishment of culture systems of human gastric epithelium for the study of pepsinogen and gastric lipase synthesis and secretion.

A main purpose of gastric secretion pertains to the digestion of dietary proteins and involves the release of pepsinogens by the fundic and antral mucosa. Over the last decade, data on human gastric physiology has expanded to equally include a significant role in fat digestion. Characteristics of human gastric lipase (HGL) such as optimum acid pH, resistance to proteolysis and non requirement of bile salts or cofactors, are advantageous in gastric lipolysis. Furthermore, the importance of HGL increases in the context of perinatal physiology and pathological situations where secretion of HGL could compensate, to some extent the depressed pancreatic activities. It is therefore important to understand the regulatory mechanisms involved in the synthesis and secretion of human gastric digestive enzymes. The establishment of an organ culture technique as well as a novel primary culture system of human gastric epithelium permitted us to demonstrate that Pg5 and HGL are colocalized in human chief cells and both digestive enzymes are efficiently synthesized and secreted in explants and primary cultures. Pepsin activity rises at the cellular level while its secretion remains constant. In contrast, cellular lipase activity drastically diminishes while being preferentially secreted. This nonparallelism supports the concept that Pg5 and HGL are differently regulated in culture. Furthermore, EGF downregulates HGL expression at the mRNA level via the p42/44(MAPK) pathway without affecting Pg5. Future studies should be designed to fully understand the cellular and molecular mechanisms involved in regulating HGL activity in normal and pathological conditions.

Cell Culture Techniques↗

PubMed2000

Expression of integrin subunits correlates with differentiation of epithelial cell lineages in developing human gastric mucosa.

Laminins may play important roles in gastric gland development due to the differential localization of their alpha chains in human fetal fundic (oxyntic) mucosa. To extend this hypothesis, the current investigation was undertaken to compare the anatomical and cellular distribution of epithelial integrin subunits with those of laminin alpha chains in the human stomach at different ages (8-22 weeks of gestation) using indirect immunofluorescence. In the body, fundus and antrum regions, the beta1 and alpha6 subunits were associated with the entire epithelium at all developmental stages in the same way as laminin chains (alpha1/alpha5) detected with 4C7 monoclonal antibody. By contrast, the alpha3 and beta4 subunits of alpha3beta1 and alpha6beta4 integrins together with the laminin alpha3-chain were concentrated in the surface and foveolus compartments composed of differentiating mucous cells. Most importantly, the alpha2 integrin subunit was expressed in a rather complex pattern: (1) it was located at the base and at cell-cell boundaries of surface/foveolar epithelium, (2) was specifically repressed in differentiating parietal cells, and (3) its expression increased in maturing glands, where it became concentrated at the basal pole of epithelial cells simultaneously exhibiting a strong reactivity for laminin-2 (alpha2-chain). Taken altogether, our observations provide new evidence for the implication of different laminins and their receptors in the development of all human gastric epithelial lineages, surface mucous cells or glandular cells. The coordinated expression of alpha2 and alpha3 integrin subunits as well as the cellular re-distribution of alpha2beta1 integrin likely represent key events for the differentiation of glandular secretory cell types, especially maturing chief cells responsible for the synthesis/secretion of gastric digestive enzymes in fundic-type glands.

Antigens, CD↗

PubMed2000

Transmission of tuberculosis in the prison of Antananarivo (Madagascar).

The prevalence of tuberculosis in the Antananarivo prison is 16 times higher than that in the general population of Madagascar. We compared the clustering of Mycobacterium tuberculosis strains within and outside the prison and studied the transmission of strains in the prison. M. tuberculosis strains isolated in 1994 to 1995 from 146 prisoners and from 260 nonprisoner patients from Antananarivo were typed using the genetic markers IS6110 and direct repeat. We compared the strains isolated from prisoners and nonprisoners and found that the clustering rate was higher within (58.9%) than outside the prison (40%) suggesting that the transmission rate was higher in prison. Of the 146 incarcerated patients, 82 were grouped into 22 clusters. We checked for possible tuberculosis transmission between prisoners with identical strains by epidemiological investigation of the various prison clusters. We found that 9.5% of the incarcerated patients could have been sources of infection and that only 15.1% could have been infected in the prison. One hundred and twenty-seven prison patients were new cases. Epidemiological data suggested that 37% of them resulted from a reactivation of an old infection, due to poor living conditions or recent transmission from an index case outside the prison.

Adolescent↗

PubMed2000

Differential expression of peroxisome proliferator-activated receptors (PPARs) in the developing human fetal digestive tract.

We investigated the spatiotemporal distributions of the different peroxisome proliferator-activated receptor (PPAR) isotypes (alpha, beta, and gamma) during development (Week 7 to Week 22 of gestation) of the human fetal digestive tract by immunohistochemistry using specific polyclonal antibodies. The PPAR subtypes, including PPARgamma, are expressed as early as 7 weeks of development in cell types of endodermal and mesodermal origin. The presence of PPARgamma was also found by Western blotting and nuclease-S1 protection assay, confirming that this subtype is not adipocyte-specific. PPARalpha, PPARbeta, and PPARgamma exhibit different patterns of expression during morphogenesis of the digestive tract. Whatever the stage and the gut region (except the stomach) examined, PPARgamma is expressed at a high level, suggesting some fundamental role for this receptor in development and/or physiology of the human digestive tract.

Antibody Specificity↗

PubMed2000

Functional characterization of the keratinocyte growth factor system in human fetal gastrointestinal tract.

Keratinocyte growth factor (KGF) is a paracrine growth factor whose mRNA has been detected in human adult and rodent gut tissues together with its associated receptor. Our objectives were to assess the presence of immunoreactive KGF ligand and receptor proteins in human fetal gastrointestinal (GI) tract segments and to evaluate the role of exogenous KGF on cell proliferation and intestinal digestive functions. KGF (26-28 kD doublet) was identified in esophagus, stomach, small intestine, and colon by Western blot. Its receptor (135 kD) was ubiquitously detected in proliferative and differentiated epithelial cells of each GI segment by use of indirect immunofluorescence (anti-bek, anti-K-sam). The addition of KGF to explants cultured in serum-free conditions greatly stimulated DNA synthesis in all GI tract tissues. The growth factor up-regulated intestinal sucrase-isomaltase and gamma-glutamyl-transpeptidase activities in jejunal explants, whereas it down-regulated these activities in colon explants. It is suggested that the KGF system likely represents an important paracrine pathway that is able to stimulate cell proliferation in all segments of the human fetal GI tract and to differentially regulate intestinal digestive functions.

Blotting, Western↗

PubMed2000

John's story: an application of the Calgary Family Intervention Model.

This article resulted from both authors sharing their professional experience; it illustrates an application of the Calgary Family Assessment Model (CFAM) and Calgary Family Intervention Model (CFIM) by Lorraine Wright and Maureen Leahey (1994). Indeed, some of the theoretical concepts presented by these authors were used to guide our analysis of the clinical situation. This brief intervention, consisting of four meetings, aimed to promote family coping during the palliative phase. Throughout each of the meetings, the nurse illustrates the principles guiding therapeutic conversations with the family, i.e. generating hypotheses, circularity, and neutrality. Through her intervention, she facilitates the continuation of the story, but without John.

Adaptation, Psychological↗

PubMed2000

Human crypt intestinal epithelial cells are capable of lipid production, apolipoprotein synthesis, and lipoprotein assembly.

The recent availability of spontaneously proliferating, non-transformed human crypt intestinal epithelial cells (HIEC) affords an opportunity to investigate lipid metabolism in undifferentiated enterocytes. The major purpose of this study was to explore the capability of undifferentiated crypt cells to synthesize, assemble, and secrete lipids and apolipoproteins. HIEC were cultured in medium with 5% fetal bovine serum for 5 to 21 d. The cells were clearly able to incorporate [(14)C]oleic acid (dpm/mg protein) into triglycerides (128,279 +/- 16,988), phospholipids (30, 278 +/- 2,107), and cholesteryl esters (2,180 +/- 207). Although improvement in lipid secretion was noted with prolongation of cell culture periods, low efficiency of lipid export (10.3 +/- 2.2% of intracellular content) characterized the HIEC. All phospholipid classes were elaborated, with phosphatidylcholine accounting for 79. 3 +/- 1.3% of cellular phospholipids. Chylomicrons were the dominant (46.4%) lipoproteins secreted, followed by high, low, and very low density lipoproteins (HDL, LDL, and VLDL) comprising 22.5, 20.2, and 10.8% of the total, respectively. HIEC elaborated most of the major apolipoprotein (apo) classes (A-I, A-IV, B-100, C, and E), but were less efficient in producing apoB-48. In contrast to the production of apoA-I and C as early as 5 days after confluence, apoA-I and A-IV were maximally expressed at 11 d. Culture media accumulated much more apoB-100 than apoB-48 (B-48/B-100 ratio 0.21 +/- 0.03), reflecting limited apoB mRNA editing. HIEC demonstrated both endogenous cholesterol synthesis and LDL receptor expression. Cholesterol synthesis was sensitive to 25-hydroxycholesterol and mevinolin, but unresponsive to LDL treatment, suggesting independent regulation pathways. In contrast, LDL inhibited receptor activity. The present findings provide the first solid evidence that immature HIEC are capable of key fat absorptive functions of well-differentiated enterocytes. The intracellular mechanisms required for lipid and apolipoprotein synthesis as well as for lipoprotein assembly are already present in intestinal crypt cells. These cells also retain the capacity for sterol enzyme and receptor expression. However, certain limitations, especially apoB-48 production and lipoprotein secretion as well as unresponsiveness of cholesterol synthesis to LDL, may be ascribed to the lack of differentiation.

Animals↗

PubMed1999

A new primary culture system representative of the human gastric epithelium.

The gastric pit-gland unit is a highly dynamic and compartimentalized structure which assumes important key functions such as acid secretion, digestion of dietary proteins and triglycerides, protection, and epithelial restitution following injury. However, in vitro models representative of the intact gastric epithelium are still lacking. The current study was undertaken to investigate the possibility of generating such primary cultures from human fetal stomach. The use of Matrisperse, a nonenzymatic solution, allowed complete dissociation of the epithelial layer and the maintenance for at least 7 days of all gastric epithelial cell types in primary culture on plastic. Indirect immunofluorescence and Western blot analyses confirmed the purity of epithelial cultures, composed of 60% mucus-secreting cells, 25% zymogenic chief cells, 5% parietal cells, and a small proportion of mitotic precursors. Their functionality was demonstrated by the presence of zonulae occludens and adherens at cell to cell contacts, [(3)H]thymidine incorporation, Periodic acid Schiff staining, and expression of growth factor receptors (EGF/TGFalpha, IGF1, HGF, KGF), gastric H(+)/K(+)-ATPase, pepsinogen (Pg5), and human gastric lipase (HGL). Chief cells were able to produce and secrete both Pg5 and HGL and to respond to EGF treatment. In conclusion, we developed a new primary culture system of human gastric epithelium characterized for the first time by the absence of added matrix and the maintenance of functional chief cells. It represents an experimental breakthrough that will serve applications in investigating the actions of hormones, mesenchymal growth factors, and basement membrane proteins on human gastric functions in vitro.

Adult↗