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T Beringer

Publications and source records attributed to T Beringer.

16 recordsLinked to original sources
PubMed1995

Apical release of base-labile fatty acyl groups commensurate with stimulation of glycoprotein sialosyl Lewis(a) secretion in colorectal carcinoma cells.

The rate of polarized secretion of a putative adhesion ligand, sialosyl Lewis(a) (19-9), by SW1116 colorectal carcinoma cells is stimulated at least 20-fold after pre-incubation with, and the incorporation of, retinoic acid (RA). In order to investigate the possible involvement of fatty acylation in the export of the epitope, purified ligands from carcinoma-cell membranes, membrane subfractions and media were analyzed during RA-induced secretion. Incorporation of radioactivity from (3H)palmitate into membrane subfractions and purified sialosyl Lewis(a) antigenic molecular species of M(r) > 150,000 (SiaLeams) was stimulated by RA treatment. Most of the intracellular lipid radioactivity which bound to solid-phase 19-9 antibody behaved chromatographically, either like ganglioside or like NH2 OH-labile acyl groups, but most of the (3H) bound to SiaLeams of post-incubation media behaved like base-labile fatty acyl groups, or free fatty acid. Release of base-labile lipid radioactivity after 3 hr (associated with antigen) was almost exclusively into the apical media of membrane inserts. Gas-liquid chromatography/mass spec. analyses of purified Sialeams revealed the presence of palmitate (16:0), as well as stearate (18:0) and oleate (18:1) fatty acyl groups. Our results suggest that fatty acylation of SiaLeams may be co-ordinated with alterations in glycosylation and participate in directing these molecules to the apical surface. Lipid analyses were consistent with ganglioside chaperonage of SiaLeams to the apical surface, where N-fatty-acylated gangliosides remain for the most part integrated into the bilayer, but some oxyester or thioester bonds may be cleaved to permit release of SiaLeams to the apical medium.

Acylation↗
PubMed1995

Repression of the Lewis fucosyl transferase by retinoic acid increases apical sialosyl Lewis(a) secretion in colorectal carcinoma cultures.

The rate of polarised secretion of sialosyl Lewis(a)(19-9) molecular species (SiaLeams) by SW1116 colorectal carcinoma cells is stimulated at least ninefold by the presence of 3 microM retinoic acid (RA). In order to investigate the intracellular origins of this augmentation, carcinoma cell membranes, membrane subfractions, and media were studied to determine alterations in sialosyl Lewis(a) levels, oligosaccharide composition, and core structures accompanying the capacity to increase export of this epitope. We observed a nine- to twentyfold increase in sialosyl Lewis(a) epitope levels in a light membrane subfraction from RA-treated cells. Antigenic molecules of < 200,000 M(r) on acrylamide gradient gels were concentrated in two doublets in the apparent M(r) range 106,000-152,000 on Western blots. Carbohydrate analyses of oligosaccharides from SiaLeams of membrane subfractions and apical media indicated much higher fucose/mannose, fucose/sialic, fucose/sialosyl Lewis(a), fucose/total CHO, and (3H) fucose incorporation in control samples than RA samples. Western blots of samples from membrane subfractions and media indicated that, in contrast to the effect of RA on the sialosyl Lewis(a) epitope, RA treatment did not augment cysteine-rich, PDTRP, blood group H-2, blood group A, and EGF receptor-like region epitopes in the media. In addition, Northern blots using the Lewis fucosyl transferase (FTIII) cDNA showed a dramatic diminution of mRNA encoding FTIII but apparently unaltered levels of sialyl transferase (ST4) mRNA. Since subterminal fucosylation of lactosyl termini blocks terminal sialylation, we conclude that one mechanism of sialosyl Lewis(a) induction in this culture system is the lower expression of the Lewis fucosyl transferase mRNA. Therefore less subterminal fucosylation of GlcNAc permits the prior sialylation of terminal Gal beta 1-3 moieties at oligosaccharide termini destined for export from the Golgi.

Base Sequence↗
PubMed1992

[Is diagnosis of toxoplasmosis within the scope of prenatal care meaningful?].

In the course of prenatal care, the sera from 5670 pregnant women were investigated. The average infection rate in the population was 39.22%; 60.39% were seronegative. To minimise the risk involved in toxoplasmosis infection, toxoplasma-antibodies must be definitely determined during prenatal care. This should be carried out simultaneously with the determination of antibodies to the rubella virus.

Animals↗
PubMed1991

Prevention of chronic pulmonary oxygen toxicity in young rats with liposome-encapsulated catalase administered intratracheally.

The lungs and hearts of young rats exposed to 100% oxygen (O2) for 8 days (27 to 35 days of age) were studied following recovery in room air at 60 days of age using morphometric, biochemical, and physiological techniques. In an attempt to prevent chronic oxygen toxicity 153 rats had transtracheal catheters surgically implanted and were treated during the O2 exposure with daily intratracheal injections of liposome-encapsulated superoxide dismutase (SOD) and/or catalase (CAT). Oxygen exposure in this model results in chronic cardiopulmonary alterations which include pulmonary hypertension, right ventricular hypertrophy, and a decrease in number of pulmonary arterioles 25 to 50 microns in diameter with increased muscularization of their walls. The volume densities of the parenchyma, parenchymal air space, and the alveolar space are increased, while that of the combined alveolar ductal and respiratory bronchiolar space is decreased. Daily intratracheal administration of liposome-encapsulated CAT (160 U) during the O2 exposure prevented these chronic changes. Liposome-encapsulated SOD (110 U) or SOD (50 U) + CAT (70 U) did not appear to have a preventive effect. During the first 3 to 5 days following oxygen exposure the lung tissue enzymes SOD, CAT, and glutathione peroxidase markedly increased. We conclude that in the young rat animal model liposome-encapsulated CAT (160 U) given intratracheally during the period of O2 exposure is safe and will prevent the chronic vascular and parenchymal damage due to oxygen toxicity.

Animals↗
PubMed1981

Flow-pressure relationships in newborn and infant spontaneously hypertensive rats.

In flow-pressure studies of the perfused "forebody', newborn (3-12 h old) SHR demonstrated significantly lower pressures than newborn WKY at high flow rates. Newborns from dams fed high salt during pregnancy showed no significant differences in flow-pressure relationships from newborns of the corresponding strain whose dams received standard salt. At 2 weeks, SHR continued on standard salt had pressures not significantly different from those of WKY at intermediate and high flow rates. However, 2-week standard salt SHR did demonstrate significantly lower pressures at low perfusion rates than 2-week WKY. 2-week SHR on high salt showed strikingly lower pressures at high flows than 2-week standard salt SHR.

Aging↗
PubMed1981

Arterial morphometry in neonatal and infant spontaneously hypertensive rats.

Media/lumen area ratios and density of arteries and arterioles were obtained from tail sections of newborn and 2-week-old spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY) on prenatal/postnatal high salt diets or standard salt diets. Fixation was by a solution which caused minimal contraction and no differences in contractile response between SHR and WKY. Standard salt SHR of both ages demonstrated significantly greater media/lumen ratios in intermediate size arterioles but not in smaller or larger arterial categories. Prenatal high salt caused significant medial thickening in 49- to 58- micrometer arterioles of newborn SHR. Maintenance on high salt to 2 weeks caused significant medial thickening i SHR arterioles of 19-38 micrometer outside diameter. High salt significantly increased the density of terminal arterioles in 2-week SHR.

Aging↗
PubMed1976

A freeze-fracture study of sarcoplasmic reticulum from fast and slow muscle of the mouse.

Sarcoplasmic reticulum (SR) of fast extensor digitorum longus (EDL) and slow soleus (SOL) muscles of the mouse was examined by freeze-fracture techniques. A distinctive feature of sarcoplasmic reticulum from the EDL is the presence of hillocks on the A-face within the terminal cisterns. These hillocks are usually arranged in a single row which is deployed parallel to the long axis of the adjacent T-tubule. Center-to-center spacing of hillocks within a row is about 70-75 nm. Hillocks are also found scattered within the collar region. The EDL of ten week mice was characterized by sheet-like terminal and intermediate cisterns, the latter being replaced in 37 week animals by thin tubular longitudinal elements of the SR which contain no hillocks or dimples. Hillocks occur only occasionally in SR from 10 or 20 week SOL muscle. In such cases the hillocks occur singly rather than in rows as in the terminal cisterns of EDL. The predominant form of SR in the SOL contains no hillocks. Total particles in the A-face of EDL-SR (2996 particles/mu2; S.D. = +/- 287) slightly exceeded that of SOL-SR (2558 particles/mu2; S.D. = 274 8 NM). Packing density of 8 nm particles was slightly higher for EDL (750/mu2) VS. SOL (700/mu2). The possible significance of these features of SR in fast and slow muscle is discussed.

Animals↗