Search PubMed⌕ Search

Biomedical subjects

H Weiser

Publications and source records attributed to H Weiser.

At least 19 recordsLinked to original sources
PubMed2001

Topical application of vitamin A reverses metaplasia of rat vaginal epithelium: a rapid and efficient approach to improve mucosal barrier function.

Retinyl palmitate and its metabolites retinol and retinoic acid control growth and epithelial differentiation. Systemic or local vitamin A deficiency induced by malnutrition, continuous chemical irritation or locally induced by inflammation causes squamous metaplastic changes in the epithelium of mucous membranes. We demonstrate that in an animal model topically applied retinyl palmitate can be taken up by the mucosal cells independently from the systemic supply. Under in vivo conditions metabolic changes in vaginal epithelium of rats were shown to be reversed by treatment with topical retinyl palmitate. - After only two days treatment squamous metaplastic vaginal epithelium in rats shows a reversal of the epithelium into a normal phenotype which continues after cessation of the treatment for 7 to 11 days. Higher concentrations and longer retention times lead to a statistically significant (p = 0.025) increase in the protection time. These data demonstrate that squamous changes induced by vitamin A deficiency can be totally reversed with topically applied retinyl palmitate.

Administration, Topical↗
PubMed1999

Expression patterns of complex glycoconjugates and endogenous lectins during fetal development of the viscerocranium.

Experimental evidence suggests that carbohydrates and their corresponding receptors (endogenous lectins) decode biological information. Therefore, the expression of complex oligosaccharides--the potential ligand part of this recognition system--during chondrogenesis and osteogenesis was determined in the viscerocranium of fetal rats by mapping the staining patterns of exogenous lectins. Results were compared with the expression of bone- and/or cartilage-specific core proteins and the binding profiles of neoglycoconjugates. These synthetic tools make possible the localization of sugar-ligand-binding sites. The spatial and temporal distribution patterns of glycoconjugates were highly dynamic and demonstrated a clear correlation with characteristic morphological modifications. The glycobiological characterization of precartilage mesenchymal cells revealed distinct differences compared to prospective bone anlagen. Especially the binding of the exogenous lectin from Griffonia simplicifolia II, that selectively visualized prechondral aggregations, reveals that regulation of early chondral growth is at least phenomenologically correlated with a relatively atypical oligosaccharide composition terminating with N-acetylglucosamine.

Animals↗
PubMed1998

Impaired responses to sweet taste in vitamin A-deficient rats.

In brief-exposure, two-choice preference tests (sucrose solution v water), vitamin A-deficient (VAD) rats exhibited a decreased preference for sucrose relative to control rats. There was no difference in total fluid intake from both choices between the two groups, nor was any significant difference found in circumvallate taste papilla keratin size. It is concluded that the impaired preference for sucrose in VAD rats is due to a specific impairment in taste sensation rather than general malaise.

Animals↗
PubMed1997

Stabilization of rat heart mitochondria by alpha-tocopherol in rats.

alpha-Tocopherol (alpha-T) acts by different mechanisms: scavenging free oxygen radicals (FOR) and stabilizing membranes; both may contribute to the prevention of the pathogenesis of diseases like cardiovascular events. The present work shows that alpha-T breaks the vicious cycle generated by damaged mitochondria. The latter stimulate the immune system increasing FOR formation that leads to more damaged mitochondria. alpha-T inhibits lipid peroxidation induced by recombinant human tumor necrosis factor (rh-TNF). Polymorphonuclear neutrophils (PMN) are activated by TNF to produce FOR causing lipid peroxidation of cardiomyocyte membranes. Since TNF is used as a therapeutic agent against certain tumors, treating patients with alpha-T could protect them against systemic side effects of TNF.

Animals↗
PubMed1997

Interaction of vitamins E and K: effect of high dietary vitamin E on phylloquinone activity in chicks.

To determine the influence of vitamin E on phylloquinone activity, one day-old chicks were raised on a masch diet supplemented with different amounts of vitamin E for 31 days. In chicks fed a diet high in vitamin E (4000 mg allrac-alpha-tocopheryl acetate/kg) but adequate in vitamin K (0.14 mg phylloquinone/kg) a threefold increase in prothrombin time and an increase in mortality rate (five out of twelve animals died from increased bleeding tendency) was observed. The inhibiting effect of high dietary vitamin E on procoagulant factors could be prevented by increasing dietary phylloquinone supplementation. Weight development, and feed utilization were insignificantly different in chicks fed different amounts and ratios of vitamins E and K1. Plasma and liver alpha-tocopherol levels correlated with dietary amounts of vitamin E. Increased phylloquinone levels in the diet did not significantly influence alpha-tocopherol concentrations in plasma and liver, but coagulopathy caused by high vitamin E intake could be reversed.

Animals↗
PubMed1996

Recognition of laparoscopic bile duct injuries by intraoperative ultrasonography.

BACKGROUND: The purpose of this study was to investigate the possibility of detecting bile duct injuries using laparoscopic intraoperative ultrasound (LIOU). METHODS: Fifty bile duct injuries were created using laparoscopic techniques in ten farmer pigs. The lesions created were: (1) partial occlusion, (2) complete occlusion (1 clip), (3) complete occlusion (2 clips), (4) transection between clips, (5) excision between clips. RESULTS: All injuries were easily visualized using LIOU. The relation of clips impinging upon or occluding the bile duct was readily visualized on LIOU in all cases. In some cases it was difficult to distinguish between partial and complete occlusion. It was also difficult to distinguish between transection and excision due to retraction of the severed bile duct. CONCLUSIONS: In cases of iatrogenic occlusion of the bile duct involving hemoclips (including transection or excision between clips), LIOU is a potentially useful modality that may allow earlier recognition and repair. Further studies are needed to evaluate the efficacy of LIOU in detection of bile duct injuries that do not involve hemoclips.

Animals↗
PubMed1996

Biodiscrimination of the eight alpha-tocopherol stereoisomers results in preferential accumulation of the four 2R forms in tissues and plasma of rats.

According to the USP, 2R,4'R,8'R-alpha-tocopheryl acetate (RRR-alpha-TAc) is 1.36 times more active than all-rac-alpha-tocopheryl acetate (all-rac-alpha-TAc). The all-rac form contains 12.5% each of the stereoisomers RRR, RRS, RSR, RSS, SSS, SSR, SRS and SRR, which display different biopotencies. In the present study, female rats fed a vitamin E-deficient diet were administered 0.82 mg of all-rac-alpha-TAc or 0.60 mg of RRR-alpha-TAc daily for up to 90 d. alpha-Tocopherol concentrations in liver, brain, adipose tissue and plasma were not significantly different among groups on treatment d 64 and 90. Thus, equipotent dosages of all-rac-alpha-TAc or RRR-alpha-TAc resulted in equimolar alpha-tocopherol plasma and tissue concentrations. A comparison with rats administered tocopherol-free placebo showed that plasma and tissue alpha-tocopherol of alpha-TAc-treated rats represented alpha-tocopherol uptake during the repletion period. The eight individual alpha-tocopherol stereoisomers in tissues and plasma were determined by chiral HPLC and capillary gas chromatography. Rats treated with all-rac-alpha-TAc preferentially accumulated the four 2R alpha-tocopherol stereoisomers (15-22% each, sum of all 2R = 70-86%) in tissues and plasma. The remaining 14-30% were 2S stereoisomers with a predominance of the SRS form. In conclusion, all-rac-alpha-TAc administration led to the presence of all eight alpha-tocopherol stereoisomers in rat liver, brain, adipose tissue and plasma. The four 2R stereoisomers including RRR-alpha-tocopherol were equally and significantly enriched. This confirmed that the configuration at C-2 of the alpha-tocopherol molecule has a major impact on stereoisomer biodiscrimination. Furthermore, the results are in agreement with the hypothesis that for alpha-tocopherol stereoisomers, biopotency differences are related to corresponding differences of alpha-tocopherol concentrations.

Adipose Tissue↗
PubMed1996

Long-term administration of high dose vitamin A to rats does not cause fetal malformations: macroscopic, skeletal and physicochemical findings.

A rat model was used to investigate whether high oral doses of vitamin A lead to fetal malformations and to what extent retinyl esters (RES) are transferred from the mother to the fetuses. Retinol and RES concentrations in plasma behave similarly in rats and humans. When high concentrations of vitamin A are administered, plasma retinol concentrations remain relatively constant, whereas plasma RES increased in parallel with the dose. To achieve an elevation from approximately 150 to > 1525 nmol x L(-1) in the experimental group before mating, female Ibm: RORO (spf) rats were fed a maintenance diet enriched with 15.2 x 10(3) retinol equivalents (RE) x kg(-1) at the start and increased stepwise to 52.5 x 10(3) for a total of 8 mo. A parallel subgroup was maintained to measure progress in experimental rats without interference by blood taking. Rats of the control group received the basal diet analyzed to contain 4.5 x 10(3) RE x kg(-1). Before mating the mean body weights of experimental and control rats were not significantly different. All-trans, 13-cis, 4-oxo-all-trans and 5,6-epoxy-all-trans retinoic acid (RA) concentrations were determined in maternal and fetal plasma. With high vitamin A intake, 4-oxo- and 5,6-epoxy RA concentrations were significantly higher in the fetuses than in their mothers. Although these high intakes of vitamin A by the rat dams resulted in high maternal and fetal plasma concentrations of vitamin A and its metabolites, fetal malformations were not observed. This may be due to the fact that circulating RES are not teratogenic and that after crossing the placental barrier, they are stored mainly in fetal liver.

Abnormalities, Drug-Induced↗
PubMed1996

Modulation of the glycoconjugate expression in the tracheo-bronchial epithelium during sustained hypovitaminosis A.

The aim of this study was to determine the influence of sustained marginal vitamin A deficiency on the morphology of glycoconjugate expression in the tracheobronchial epithelium of guinea pigs. The distribution of oligosaccharide chains was investigated by applying a panel of 24 lectins. Glycosaminoglycans were detected by histochemical techniques. Number as well as morphology of ciliated cells showed no significant alterations in hypovitaminosis A. In contrast, the quantity of goblet cells was constantly decreased. A considerable reduction of secretory granules was also observed in these cells. Cytomembranes of ciliated cells (especially in the area of ciliar extensions) showed constant alterations in the patterns of lectin binding in vitamin A-depleted guinea pigs. Our results demonstrate a significant augmentation of accessibility of fucosyl molecules in proximal domains of glycoconjugates of ciliary membranes, whereas the presence of mannose structures seemed unchanged. In distal bronchioli, terminal N-acetylgalactosamine molecules were expressed. During marginal vitamin A deficiency, ciliary cells were specially labelled by GSA I(B), indicating presentation of terminal galactose molecules in alpha-position. Additionally, the cytoplasm of epithelial cells demonstrated enhanced concentrations of polyantennary oligosaccharide core structures. Staining of epithelial cells by VVA was restricted to control specimens. Abundance of N-acetylglucosamine residues on the non-reducing terminus of oligosaccharides was significantly enhanced in the connective tissue of depleted animals as demonstrated by the binding patterns of GSA II. We suggest that altered oligosaccharide patterns may contribute to enhanced predisposition to tracheobronchial infection in marginal vitamin A deficiency.

Animals↗
PubMed1995

Characterization of glycoconjugate expression during development of Meckel's cartilage in the rat.

The staining patterns of 24 biotinylated lectins were analyzed in serial sections of the mandible of 13- to 21-day-old rat embryos by means of the avidin-biotin-peroxidase method. A ubiquitous distribution of binding sites was demonstrated after incubation with Con A (Canavalia ensiformis), DSL (Datura stramonium; except bone matrix), and WGA (Triticum vulgare). ECL (Erythrina cristagalli), GSL I (Griffonia simplicifolia), SJA (Saphora japonica), VVL (Vicia villosa), DBA (Dolichus biflorus), UEA I (Ulex europeus), and LTA (Lotus tetragonobolus) were constantly negative. In early stages of development, GSL II (Griffonia simplicifolia II) was a selective marker of prechondral blastema. In contrast, PNA (Arachis hypogaea) did not stain condensing mesenchyme. During chondrogenesis of Meckels's cartilage a general decrease of lectin binding was observed. Mature cartilage matrix was constantly negative. Chondrocytes were marked by the lectins PSA (Pisum sativum), WGA, PHA-E, and PHA-L (Phaseolus vulgaris E and L). A strong GSL II binding was restricted to the mesial-superior region of the perichondrium. In later stages, several lectins revealed significant differences between preskeletal ("central") areas and the remaining ("peripheral") mesenchyme. A clear binding reaction was noted in central regions by applying LEA (Lycopersicon esculentum) and STL (Solanum tuberosum), while the peripheral tissue was only faintly stained. Developing bone was specifically marked by succinylated WGA (sWGA). The lectins LCA (Lens culinaris) and RCA (Ricinus communis) bound to fibers and extracellular matrix of the connective tissue. Jacalin (Artocarpus integrifolia) and SBA (Glycine max) binding sites were found in macrophages. Affinity of VAA (Viscum album) increased parallel with maturation of endothelial cells. Specific lectin-binding patterns revealed no correlation with the distribution of glycosaminoglycans. The results demonstrate a general reduction of oligosaccharide structures during development of Meckel's cartilage. From our observations we conclude that intralaminar glucose and/or mannose sequences as well as terminal sialic acid molecules are ubiquitously distributed, while terminal alpha-fucose was constantly negative. Lectin-binding patterns of macrophages may reflect the presence of specifically linked terminal galactose. Our findings indicate that oligosaccharides terminating in N-acetylglucosamine are bone-specific. The significance of the restricted staining of the perichondrium by GSL II remains to be elucidated.

Animals↗
PubMed1995

Glycoconjugate expression of chondrocytes and perichondrium during hyaline cartilage development in the rat.

Alterations in the expression of glycoconjugate structures during cartilage development in the chondrocranium, nasal skeleton, Meckel's cartilage, limb buds, vertebral bodies and ribs were investigated comparatively in 13 to 21-d-old rat embryos. The binding patterns of 24 biotinylated lectins were analysed in serial sections and compared with results obtained using histochemical methods. Proteoglycan distribution, assessed by conventional staining procedures, was not associated with lectin binding sites. During early fetal development, hyaluronate concentrations were enhanced in areas of prospective chondrogenesis. With few exceptions, the lectins showed a general increase in intensity of binding to mesenchymal structures. Con A (Canavalia ensiformis), DSL (Datura stramonium), and WGA (Triticum vulgare) displayed a ubiquitous distribution of binding sites. After incubation with LCA (Lens culinaris), PSA (Pisum sativum), STL (Solanum tuberosum), and VAA (Viscum album), characteristic differences in binding intensity between focal areas of developing mesenchyme were seen. DBA (Dolichus biflorus), ECL (Erythrina cristagalli), GSL I (Griffonia simplicifolia), LTA (Lotus tetragonobolus), SJA (Saphora japonica), UEA I (Ulex europaeus) and VVL (Vicia villosa) consistently failed to bind. During chondrogenesis a general reduction of lectin staining was detected. In early stages of development GSL II (Griffonia simplicifolia) was a specific marker of the prechondral blastema in the viscerocranium. PNA (Arachis hypogaea) selectively labelled the prevertebral blastema. In contrast, condensing mesenchyme of limb buds and viscerocranium was not stained. Using RCA (Ricinus communis), it was possible to distinguish chondroblasts from mature cells. All chondrocytes were stained by PSA, PHA-E, PHA-L (Phaseolus vulgaris E and L), and WGA, whereas Con A, LCA, and GSL II detected distinct differences between cartilage with different localisations. Cartilage matrix was constantly negative. Applying GSL II it was possible to distinguish specific segments of the perichondrium. From our results we conclude that especially high mannose oligosaccharides are amplified during development. Terminal sialic acid molecules, branched intralaminar glucose and/or mannose, respectively, internal galactose-(beta 1,4)-N-acetylglucosamine sequences as well as galactose-(beta 1,3)-N-acetylgalactosamine sequences in a preterminal position are diffusely distributed in mesenchymal tissue. In contrast, no evidence for the presence of terminal GlcNAc(beta 1,4)GlcNAc sequences and terminal alpha-fucosyl residues in (1,2) or (1,3)-linkage was obtained. Chondrogenesis appears to be correlated with a general reduction in the extent of expression of oligosaccharide structures. No proof of terminal N-acetylgalactosamine and alpha-galactose moieties was found, whereas our staining results document the expression of terminal beta-galactose structures in restricted areas of the developing mesenchyme.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylglucosamine↗
PubMed1994

Distribution patterns in glycoconjugate expression during the development of the rat palate.

The distribution of complex carbohydrate structures during the embryonic development of the rat palate was analysed by examining lectin-binding patterns in serial paraffin and cryostat sections. With few exceptions, the binding patterns showed a general increase in lectin receptors in the more developed stages of palatogenesis. High mannose oligosaccharides were especially amplified during development. Terminal fucose molecules were not expressed. In contrast, terminal sialic acid molecules were ubiquitously distributed in epithelial and mesenchymal tissues. Non-sialylated terminal N-acetylglucosamine was specifically restricted to evolving bone matrix. Before palatal fusion, quantitative but not qualitative differences were detected between oral, nasal, and medial-edge epithelial surfaces. The only exception was LCA, which specifically marked epithelial cells at the tip of palatal shelves. A very selective affinity for Jacalin was demonstrated in the oral epithelium of the palate after day 16, suggesting the presence of sialylated terminal galactose-(beta-1,3)-N-acetylgalactosamine. PNA specifically marked the basal lamina of the oral side of palatal processes. The binding patterns of DBA, GSL IA, SBA, and VVA indicated that the epithelium of the tongue is characterized by terminal alpha- and beta-galactose residues, whereas palatine cells possess only molecules with beta-anomery. During palatogenesis, glycosaminoglycans patterns were significantly modified. Our data suggest that alteration of complex carbohydrate structures may play a central role in modulating cell-cell and cell-matrix interactions. The significance of these findings, however, remains to be elucidated.

Acetylglucosamine↗
PubMed1994

[The effect of vitamin C and zinc on the copper-induced increase of cadmium residues in swine].

In commercial pig fattening, copper is added to the feed in amounts that greatly exceed the requirements of the animals. On the one hand, this improves weight gain, but on the other, as we were able to recently prove, the retention of the heavy metal cadmium rises in the kidney, in the liver and in muscle. In a feeding experiment with female and male castrated piglets, we tried to counter the copper-induced rise in cadmium (175 mg Cu/kg feed) by adding zinc or vitamin C to the diet. While addition of 100 or 200 mg zinc per kg of diet had no influence, the addition of 1000 mg vitamin C reduced the elevated cadmium values in the kidneys and livers to values only determined with a low copper supplementation of 35 mg copper per kg of feed. This positive vitamin C effect not only occurs in cases of high copper supplementation (175 mg Cu/kg feed); when the pigs were given only 35 mg copper per kg of feed, vitamin C also reduced the cadmium content in the organs by 35 to 40%. This indicates that vitamin C improves the quality of food gained from animals for human consumption in both conditions.

Animal Feed↗
PubMed1994

Vitamin B6 deficiency experimentally-induced bone and joint disorder: microscopic, radiographic and biochemical evidence.

In the present study the effect of pyridoxine deficiency on the ultrastructure and morphology of bone and its metabolism was examined in the rapidly growing chick. Pyridoxine-deficient animals had tibias of reduced dry weight and cortical thickness. Histomorphometry demonstrated a disproportionately high eroded surface, lower amount of osteoid tissue and reduced mineralized trabecular width. Anterior-posterior radiographs of the tibiotarsometatarsal joint showed reduced secondary ossification centres and coarse trabeculation. Decalcified metaphyseal cartilage showed irregular trabeculas and a markedly reduced amount of Fast-green counterstain matrix suggesting that there is less collagen present and in turn less availability for matrix to be laid down for later calcification. Plasma activity of the bone alkaline phosphatase isoenzyme (EC 3.1.3.1) was decreased. Plasma Ca and PO4 levels did not vary. The present bone study referring to a pseudo-lathyritic state in which collagen maturation is not completely achieved supports the hypothesis that pyridoxine is an essential nutrient for the connective tissue matrix.

Alkaline Phosphatase↗
PubMed1994

Effects of dietary proteins and yeast Saccharomyces cerevisiae on vitamin B6 status during growth.

Male rapidly growing broiler chicks were fed a moderate (22%) or a high protein (30%) well-balanced diet containing yeast Saccharomyces cerevisiae (2%) and consisting of soy protein isolate (Soyamin) or a purified amino acid mixture. The vitamin B6 status was assessed according to the in vitro stimulated activity of aspartic aminotransferase (activation coefficient; AC) and pyridoxal phosphate concentrations in plasma and erythrocytes. No weight difference was found between age-matched control and B6-deficient animals fed the Soyamin diet containing yeast. None of the deficient animals presented signs of malfunctions of the central nervous system. These animals grew well and their skeletal development was normal after 6 weeks of age. Due to the presence of yeast, increasing dietary protein intake did not augment the metabolic requirement for pyridoxine. The removal of yeast from the Soyamin diet provoked a severe symptomatic deficiency (AC 1.5). It seemed that yeast did more than promoting growth. It also protected against a lack of vitamin B6: feed utilization was not impaired. The present study showed that a low level of 0.6 mg vitamin B6/kg in a corn-Soyamin diet containing yeast was adequate to maintain normal growth and to avoid neurological symptoms. The pyridoxine requirement for normal growth and absence of convulsions has been reported to be approximately 3 mg/kg diet.

Animal Feed↗
PubMed1994

[Relationship between plasmatic lipids and fat soluble vitamins in Guatemalan periurban elderly].

The levels of plasmatic lipids and fat liposoluble vitamins were measured in 107 elderlies (29% males, 71% females) who were residents of a poor periurban neighborhood of Guatemala City. The age ranged between 60-103 years (means +/- sd 69 +/- 8). The mean and sd for the plasmatic levels of lipids and vitamins were (ranges in parenthesis): cholesterol 220 +/- 42 mg/dl (128 to 428); triglycerides: 189 +/- 92 mg/dl (54 to 513); retinol 50 +/- 16 ug/dl (4.5 to 103); beta-carotene 17 +/- 12 ug/dl (12 to 60), tocopherol 1.32 +/- 0.36 mg/dl (0.54 to 2.46). A significant correlation was found in both sexes between cholesterol and retinol (r = 0.3, p < 0.05) and cholesterol and tocopherol (r = 0.4, p < 0.05), triglycerides and retinol (r = 0.3, p < 0.05). Cholesterol and beta-carotene was also significant in women (r = 0.5, p < 0.05). The correlation between triglycerides and beta-carotene by gender was not significant.

Aged↗
PubMed1994

Effects of modifying dietary protein in the presence and absence of vitamin B6, on the regulation of plasma calcium and phosphorus levels--positive impact of yeast Saccharomyces cerevisiae.

Vitamin B6 status has been assessed according to the activation coefficient (AC) of plasma aspartic aminotransferase (AST) activity. Fast-growing male one-day-old broiler chicks, divided into two groups (supplemented with pyridoxine or not), were fed a soy protein isolate (Soyamin) or a purified amino acid diet containing or not Saccharomyces cerevisiae yeast (2%), primarily used to promote the growth of the B6-deficient animals. In one experiment, the protein level of the diet has been increased to augment the metabolic demand for PN. The B6-deficient Soyamin diet B containing yeast produced a mild deficiency (without incidence of morbidity and mortality) and the deficiency was severe (appearance of neurological symptoms after 10 days, AC 1.5) when yeast was deleted (diet A). The inclusion of yeast in both Soyamin and amino acid diets significantly increased plasma Ca and Pi levels (p < 0.001) whereas increasing the protein intake (diet C) had an inverse effect, reflecting an inhibitory effect on intestinal absorption of these minerals. Changes in plasma Ca and Pi levels due to dietary treatments were summarized in terms of their theoretical ion product. The amino acid diet D produced the lowest Ca x Pi ion product and the highest value was obtained with the yeast-containing diets B and E, regardless of the vitamin B6 intake and the dietary protein source. Plasma Ca and Pi levels were simultaneously elevated in severe vitamin B6 deficiency (diet A) as compared to control group (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗