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Biomedical subjects

F Gudat

Publications and source records attributed to F Gudat.

179 records · Page 10Linked to original sources
PubMedDate not supplied

delta Antigen in hepatitis B: immunohistology of frozen and paraffin-embedded liver biopsies and relation to HBV infection.

The finding that the recently described hepatitis B (HB)-associated delta antigen (delta Ag) is preserved in pronase-treated, formalin-fixed paraffin sections allowed a combined prospective and retrospective immunohistological study of its occurrence in 571 liver biopsies. Among 116 frozen biopsies (69 HBAg seropositive, 47 HBAg seronegative) and 455 paraffin-embedded biopsies (296 HBAg seropositive, 159 HBAg-negative), delta Ag was found in 10 HBAg seropositive patients. With the exception of 1 patient with chronic persistent HB, all had chronic-active HB and none had acute HB; 5 patients were i.v. drug abusers. In follow-up biopsies, the delta Ag persisted with HBsAg for as long as 6 years. The expression of delta Ag showed similarities to the HBcAg system including nuclear localization, mixed nuclear cytoplasmic expression, and coexistence with anti-delta in blood. The findings are compatible with the hypothesis that delta Ag represents a transmissible, defective viral agent which requires HBV as a helper and may modulate, but not terminate, ongoing HBV infection.

Antigen-Antibody Complex↗
PubMedDate not supplied

Demonstration of albumin receptors on isolated human hepatocytes by light and scanning electron microscopy.

The presence of albumin receptors on the plasma membrane of isolated human hepatocytes was investigated employing albumin-coupled latex minibeads. Hepatocyte-latex reaction was visualized by phase contrast and scanning electron microscopy. The experiments demonstrate that hepatocytes exhibit binding activity for polymeric and monomeric forms of glutaraldehyde-treated albumin. Additionally, the reaction was shown to be species-nonspecific. These findings support the hypothesis that polymerized albumin may act as a bridge between receptors on hepatitis B virus and human hepatocytes.

Cell Membrane↗
PubMedDate not supplied

Prevalence and significance of anti-HBc IgM (radioimmunoassay) in acute and chronic hepatitis B and in blood donors.

Anti-HBc IgM was determined by a modified radioimmunoassay (RIA) in 35 patients with acute hepatitis B, 35 patients with chronic hepatitis B (7 with chronic persistent, and 28 with chronic active hepatitis), 157 HBsAg positive blood donors, and in 143 HBsAg negative but anti-HBc positive donors. The results of the RIA test were compared with those obtained by an ELISA technique. In chronic hepatitis, anti-HBc IgM was correlated with the occurrence of HBeAg, anti-HBe, Dane particles in the serum, HBsAg, and HBcAg in liver tissue and with biochemical and histological degrees of hepatic inflammatory activity. In acute self-limited hepatitis B, anti-HBc IgM (RIA and ELISA) was initially positive in all 35 patients. Twelve months after the acute illness, 94% of the patients were negative for anti-HBc IgM in the RIA test with only one patient showing a persistence of up to 18 months, whereas in the ELISA test anti-HBc IgM persisted in 17% of the patients over 2 years. In chronic hepatitis, the occurrence of anti-HBc IgM (RIA) showed a strong relation with the inflammatory activity, the anti-HBc IgM positive patients revealing a significantly more severe liver disease than did anti-HBc IgM negative patients. Anti-HBc IgM (RIA), however, did not correlate with the occurrence of HBeAg and Dane particles in the serum and HBcAg in liver tissue of patients with chronic hepatitis. Of the 157 HBsAg positive blood donors, anti-HBc IgM (RIA) could be demonstrated in 10 (6%), but in none of the 143 HBsAg negative, but anti-HBc positive donors, as compared to 43 (27%) and 9 (6%), respectively, in the ELISA test. Comparing the two test methods, the RIA exhibits higher specificity than did the ELISA due to a better blocking of nonspecific reactions, but possibly somewhat lower sensitivity. In this form, however, the RIA test is a more useful tool in the diagnosis of the different forms of hepatitis B virus infection and in determining the severity of chronic hepatitis B.

Blood Donors↗
PubMedDate not supplied

Nuclear particles of non-A, non-B type in healthy volunteers and patients with hepatitis B.

In an electron microscopic study, nuclear aggregates of virus-like spherical and tubular particles measuring 20 to 29 nm in diameter were found in 5 of 7 clinically healthy volunteers with normal liver histology, 6 of 10 patients with hepatitis B and 17 of 18 patients with hepatitis non-A, non-B. The incidence of hepatocytes containing nuclear particles was approximately 0.5 to 2% in all three groups. We conclude that these nuclear particles are not specific ultrastructural markers of hepatitis non-A, non-B in man as originally claimed for experimental hepatitis non-A, non-B in chimpanzees.

Adolescent↗
PubMedDate not supplied

Electron microscopy of isolated human hepatocytes. (Micromethods for scanning and transmission electron microscopy).

We have investigated, by scanning and transmission electron microscopy (SEM and TEM), the cell surface morphology of isolated human hepatocytes. For this purpose, liver cells were mechanically isolated from surgical or needle liver biopsies, fixed in 3% glutaraldehyde and post-fixed in 2% osmium tetroxide. In order to handle a low number of cells, a particular procedure for harvesting hepatocytes on coverslips has been developed for SEM and an in situ embedding procedure in polyethylene-embedding capsules was applied for TEM. A rough membrane exhibiting short, uniform microvilli and pores of 0.1 mu in diameter was the main feature of isolated liver cells. Furthermore, single hepatocytes showed no polarity and junctional or bile canaliculus remnants were rarely observed. However, differences in surface configuration were noted in relation to culture conditions, such as oxygen and temperature during isolation procedures. SEM, when controlled by TEM for intracellular preservation, is proposed as a reliable method for screening small quantities of hepatocyte suspensions, for intact cells and for the study of surface configuration under experimental conditions.

Cells, Cultured↗
PubMedDate not supplied

Intralipid-based short-term total parenteral nutrition does not impair small intestinal mucosa-related cellular immune reactivity in the healthy rat.

BACKGROUND: The lipid component of total parenteral nutrition (TPN) has reportedly been associated with trophic effects on the intestinal mucosa and suppressive effects on the immune system. METHODS: We have challenged these hypotheses using a 7-day TPN rodent model comparing the effects of isocaloric, isonitrogenous lipid-based (TPN-lipid, 50% of calories as long-chain triacylglycerol) and carbohydrate-based TPN (TPN-CH, 100% of calories as carbohydrates) on mucosal morphology and immune function. Enterally fed animals were included to establish a baseline for immunologic read-outs. The study was performed in healthy, metabolically stable animals to avoid interference by septic or trauma-related stress factors. RESULTS: Both TPN regimens resulted in a significantly smaller weight gain (TPN-lipid, 29.8 +/- 4.0 g; TPN-CH, 30.3 +/- 4.4 g) compared with enterally fed reference animals (49.2 +/- 3.2 g; p = .007), with no difference in nitrogen balance between the TPN groups. Mucosal sucrase activity was significantly lower in both TPN groups (TPN-lipid, 8.8 +/- 1.0 x 10(-7) katal per gram (kat/g) of protein; CH: 11.9 +/- 1.6 x 10(-7) kat/g of protein) compared with enteral feeding (17.4 +/- 0.9 x 10(-7) kat/g of protein; ANOVA: p = .0007). Morphometric analysis of the small intestine revealed no differences between the two TPN groups although a significantly depressed villus height in the TPN-lipid group could be observed in comparison to enterally fed reference rats (TPN-lipid, 0.47 +/- 0.02; TPN-CH, 0.50 +/- 0.01; enteral, 0.56 +/- 0.02 mm; ANOVA: p = .0298). Light and electron microscopy revealed a normal surface architecture in all three groups of rats. Cellular immune reactivity was evaluated using a novel specific immunization protocol: animals were immunized against OVA 4 weeks before TPN. OVA-induced lymphoproliferative responses and phenotypic data from draining popliteal and mesenteric lymph nodes were evaluated after the different regimens. Results did not differ among the three groups. CONCLUSIONS: In healthy rodents, short-term lipid-based and carbohydrate-based TPN regimens lead to limited mucosal atrophy with preserved surface architecture compared with enteral feeding. However, peripheral and mesenteric cellular immune responsiveness after both TPN regimens remained comparable to enterally fed reference animals. Therefore, mesenteric and systemic cellular immune reactivity does not appear to be impaired by lipid-based or carbohydrate-based TPN.

Animals↗
PubMedDate not supplied

Glutamine peptide-supplemented long-term total parenteral nutrition: effects on intracellular and extracellular amino acid patterns, nitrogen economy, and tissue morphology in growing rats.

Glutamine (GLN) is a nonessential amino acid that is not included in current regimens for parenteral nutrition because of its chemical instability. This study tested the hypothesis that GLN supplementation during long-term total parenteral nutrition (TPN) (3 weeks) would enhance GLN availability, thereby improving nitrogen economy and growth in a growing rat model: Standard TPN delivering 300 kcal/kg per day (lipid:carbohydrate = 1.1) including 2.1 g of nitrogen per kilogram per day in an all-in-one solution was compared with an isonitrogenous, isocaloric, and isovolemic TPN regimen with 0.29 g of nitrogen per kilogram per day substituted by GLN derived from the dipeptides glycyl-GLN and alanyl-GLN (TPN GLN). Enterally fed controls were included. Analysis was confined to nonbacteremic animals with negative blood culture, in which extracellular and intracellular amino acid concentrations including GLN, nitrogen balance, serum protein concentrations, growth, and histologic sections of liver and small-bowel mucosa (light and scanning electron microscopy) were evaluated. Hepatic intracellular GLN concentrations were significantly lower, in animals receiving GLN-free TPN (11.7 +/- 1.6 nmol/mg fat-free dry and solid tissue mass, n = 9) compared with both GLN-supplemented TPN (16.0 +/- 3.0, n = 7) and enteral feeding (18.2 +/- 1.8, n = 6) (p < .001). Corresponding results were found for intracellular GLN concentrations in skeletal muscle (TPN standard 12.5 +/- 3.1, TPN GLN 14.7 +/- 3.1, enteral control 17.3 +/- 2.3, p < .05), intestinal mucosa, and spleen as well as for plasma concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMedDate not supplied

Analysis of proliferative activity using Ki-67 on cervical precancerous lesions and the relationship to p53 expression.

Neoplastic cell growth rate and the p53 expression have been recently analysed in invasive cervical carcinoma. Samples of 20 specimens with normal cervical epithelium and 73 specimens of dysplasia and carcinoma in situ (CIS) were immunostained with monoclonal antibodies to p53 and Ki-67 to examine the interrelationship between p53, Ki-67 and HPV status in cervical intraepithelial neoplasm. The presence of HPV was assessed by in situ DNA hybridization. Of dysplasias and CIS 79% were HPV positive. The growth rate of neoplastic cells was significantly correlated to the histological grade and the HPV status. The highest proliferation was found in poorly differentiated HPV 16/18 positive precancerous lesions. The analysis of the p53 expression showed no difference between various histological grades. However, the p53 oncoprotein was expressed significantly lower in HPV 16/18 positive neoplasms. The assessment of neoplastic cell growth rate offers a potentially valuable approach to predicting biological behaviour in intraepithelial neoplasms.

Biomarkers, Tumor↗