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Biomedical subjects

R Schreiber

Publications and source records attributed to R Schreiber.

At least 19 recordsLinked to original sources
PubMed1992

A model to estimate the expression of the dystrophin gene in muscle from female Becker muscular dystrophy carriers.

The purpose of the present investigation was to assess the possibility of building a model to estimate, through dystrophin western blotting analysis, the expression of the DMD/BMD gene in muscle from heterozygotes. Dystrophin was analysed by mixing in increasing proportions (from 0% to 100%) aliquots of solubilised muscle from BMD patients with a qualitatively abnormal dystrophin and a normal male control. The intensity of the abnormal bands, which could be detected starting with 20% of muscle from the BMD patient, increased progressively according to the affected muscle concentration. In five obligate BMD carriers, two dystrophin bands were observed (corresponding to the products from the X bearing the normal and the BMD alleles), even among those with normal serum enzyme activities. Surprisingly, in the four obligate BMD carriers related to patients in whom an additional dystrophin fragment of 250 kd was present (two of them with raised serum enzymes), this band could not be seen, suggesting that the stability or the mechanism responsible for the synthesis of abnormal dystrophin products differs in heterozygotes compared to affected patients.

Adult↗
PubMed1991

Cascade modulation by anti-tumor necrosis factor monoclonal antibody of interferon-gamma, interleukin 3 and interleukin 6 release after triggering of the CD3/T cell receptor activation pathway.

In addition to being potent immunosuppressants, anti-CD3 monoclonal antibodies (mAb) are powerful mitogens in both humans and mice. The first antibody injection consistently induced an initial monocyte-dependent T cell activation with subsequent release of both monocyte- and T cell-derived cytokines [mainly tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin (IL) 2, IL 3 and IL 6) into the circulation. This cytokine release is associated with a self-limiting, often severe, acute physical reaction in both patients and mice. We report here that a single injection of anti-TNF mAb prior to anti-CD3 administration not only neutralizes the biological activity of TNF but also strongly affects the release of other cytokines, with notably an up-regulation of IFN-gamma release and a down-regulation of IL 3 and IL 6 release. Conversely, pretreatment with anti-IFN-gamma mAb increases IL 3 and IL 6 production but does not affect TNF levels. Taken together, these data point to a pivotal role of IFN-gamma in the anti-CD3-induced cytokine cascade and reveal new regulatory pathways between TNF and IFN-gamma. With regard to the clinical implications of these findings, as anti-TNF mAb prevents anti-CD3-induced sickness in mice, whereas anti-IFN-gamma does not, such a therapeutic approach might be of value in OKT3-treated patients.

Animals↗
PubMed1991

Familial biliary atresia in three siblings including twins.

We report a North American Indian family of five children in which dizygotic twin sisters and a third sibling had biliary atresia. This is in contrast to many reports of discordant biliary atresia in twins. Added to 29 previously documented cases of familial biliary atresia, these three cases support the theory that both genetic and acquired factors play a role in the pathogenesis of this disease.

Biliary Atresia↗
PubMed1991

[An electrolyte-adapted heparin solution for the determination of blood gases and electrolytes in whole blood].

Blood gases, pH, sodium, potassium, chloride, and ionised calcium in whole blood samples can be determined simultaneously in modern instruments. Preparing syringes with conventional heparin solutions causes a relevant bias of the electrolyte concentrations (especially K+ and Ca2+) by dilution of the sample. Additionally, ionised calcium is decreased by binding to heparin. The solution described in the present paper yields a final heparin concentration of 4-6 mU/l, thus eliminating the calcium binding effect. The dilution effects are antagonised by an electrolyte composition that is similar to normal plasma. The heparin solution is commercially available.

Blood Gas Analysis↗
PubMed1991

Inter-mouse strain differences in the in vivo anti-CD3 induced cytokine release.

Triggering of the CD3 molecule by in vivo injection of the hamster anti-murine CD3 monoclonal antibody 145-2C11 in adult BALB/c mice leads to massive although transient T cell activation. High levels of tumour necrosis factor (TNF), interferon-gamma (IFN-gamma), IL-2, IL-3 and IL-6 are released into the circulation 1 to 8 h after a single 10 micrograms 145-2C11 i.v. injection. This release induces an impressive self-limited physical reaction associating hypothermia, hypomotility (as assessed by actimetry), diarrhoea, piloerection and even death when high doses (a single dose of greater than 100 micrograms/mouse injection) are administered. In vivo injection of 145-2C11 to other selected mouse strains, namely NZW, CBA/J and C3H/HeJ, induced both different cytokine release patterns and sickness. 145-2C11 induced significant release of TNF and IL-2 in all four strains. At variance, IFN-gamma was only detected in BALB/c mice sera which, in terms of physical reaction (hypothermia and hypomotility) were the most affected. Higher and long-lasting circulating IL-3/GM-CSF levels were present in CBA/J sera, correlating with a later recovery. These results underline heterogeneity in the in vivo cell activation pattern among different mouse strains, when triggering T lymphocytes via the CD3/Ti molecule as compared to exclusive targeting of monocyte/macrophages by means of lipopolysaccharide.

Animals↗
PubMed1990

Cytokine-related syndrome following injection of anti-CD3 monoclonal antibody: further evidence for transient in vivo T cell activation.

In vivo injection of the hamster anti-murine CD3 monoclonal antibody 145 2C11 into BALB/c mice induces a massive systemic release of several cytokines. Very high circulating levels of tumor necrosis factor are detected both by enzyme-linked immunosorbent assay and L-929 bioassay 90 min following a single injection of 10 micrograms/mouse 145 2C11. Peak circulating levels of exclusively T cell-derived products such as interferon-gamma, interleukin 2 and interleukin 3 are also detected 90 min to 8 h post-injection. Importantly, this cytokine release is transient since none of these cytokines are still present 12 to 24 h post-injection. In parallel to cytokine release, 145 2C11-treated mice (10 micrograms/mouse) exhibit somnolence, hypomotility (quantified by actimetry), hypothermia, diarrhea and piloerection. At this dosage, the physical reaction is not lethal and reverses in all mice by 48 h post-injection. Severe but again reversible anatomopathological changes are also observed: massive cellular depletion, necrosis and edema of lymphoid organs, leakage syndrome and inflammatory cell infiltrates of the lung, cell vacuolization, necrosis and vascular congestion of the liver. All these data are similar to the clinical and immunological manifestations of the OKT3-induced reaction in patients and, thus, provide an invaluable experimental tool to study its mechanisms and explore its prevention.

Animals↗
PubMed1990

Reduction of morbidity and cytokine release in anti-CD3 MoAb-treated mice by corticosteroids.

In keeping with the in vitro mitogenic properties of anti-CD3 MoAbs, the first injections of anti-CD3 are invariably responsible for an in vivo cellular activation. This activation induces a massive cytokine release in the circulation (TNF, IFN gamma, IL-2, IL-6, and IL-3). Paralleling this release, a severe clinical reaction occurs in OKT3-treated patients and in 145 2C11-treated mice. Corticosteroids both in vitro and in vivo inhibit the production of several cytokines involved in the anti-CD3 reaction. A single 1 mg hydrocortisone dose was administered to 145 2C11-treated mice according to different kinetics schedules. When given 1 hr prior to the anti-CD3 MoAb, hydrocortisone exerted a beneficial effect on the mouse physical reaction. Hypothermia was totally abrogated at the 4-hr time point. Diarrhea decreased by 50%. Hypomotility improved although not significantly. This improvement correlated with a major modification in the anti-CD3 pattern of cytokine release. At the 90-min blood withdrawal time point cytokine serum levels showed a 100% decrease for IFN gamma, an 88% decrease for IL-6, and 85% decrease for IL-2, and a 75% decrease for TNF. At 4 hr IL-2 serum levels were diminished by 65%; IL-6, IL-3, and IFN gamma serum levels were comparable to controls; and, interestingly, TNF was still detected, whereas it has already disappeared when 145 2C11 was administered alone. Importantly, when given more than 1 hr prior to anti-CD3 injection, corticosteroids were ineffective. To conclude, high doses of corticosteroids must be given with a precise kinetics--i.e. 1 hr prior to anti-CD3 MoAb--to achieve their maximal beneficial effect in the prevention of the anti-CD3 reaction.

Adrenal Cortex Hormones↗
PubMed1989

A specific Fc gamma receptor on cultured rat mesangial cells.

Mesangial cells represent specialized pericytes in the renal glomerulus that contribute to the regulation of a variety of glomerular functions. Recently we and others have shown that cultured mesangial cells bind and take up immune complexes in an Fc-dependent manner leading in turn to generation of PGE2, reactive oxygen, and platelet-activating factor. The present studies were designed to further characterize potential Fc-gamma R on mesangial cells. Binding assays with either monomeric or heat aggregated (HA) [125I] labeled rat subclass-specific IgG were performed at 4 degrees C for 2 h on subcultured rat mesangial cells. Monomeric rat IgG2a, IgG2b, IgG1 and HA IgG2a bound only nonspecifically. Saturable Fc-dependent binding occurred for HA IgG2b and HA IgG1 though maximal binding and affinity were much higher for IgG2b. The presence of an Fc-gamma R was confirmed by surface protein iodination of mesangial cells (MC) and immunoprecipitation with either a polyclonal or mAb 2.4G2 prepared against murine Fc-gamma R. Both antibodies precipitated a 45-kDa iodinated protein band from cultured rat MC that comigrated with that from murine macrophage J774 cells on SDS-PAGE. This protein band also reacted with the polyclonal anti Fc-gamma R antibody on immunoblots. In contrast rat renal papillary epithelial cells were negative. The 45-kDa protein recognized by the rat anti-Fc-gamma R antibody 2.4G2 probably represents the binding site for HA IgG2b, as the 2.4G2 antibody also blocked binding of HA IgG2b. By immunofluorescence microscopy all MC stained positively with the polyclonal anti-Fc-gamma R antibody. A cDNA probe for the Fc-gamma RII-alpha on murine macrophages hybridized to mRNA from cultured rat MC which was of the same size (though less abundant) as that from J774 macrophages. These results further characterize the Fc-gamma R on cultured rat MC, and raise the possibility that the mesangial Fc-gamma R may play a role in the handling of immune-complexes by the renal glomerulus.

Animals↗
PubMed1989

Sideways killing: the cytolysis of Fc receptor-bearing cells through bridging to cytolytic T lymphocytes by antibodies specific for the T-cell receptor-T3 complex.

Cytolytic T lymphocytes (CTL) cause cytolysis of foreign or virus-infected syngeneic cells when recognition of the target plus major histocompatibility complex (MHC) occurs via the T-cell receptor (TCR). The recognition event leads to intimate contact between the two cells and activation of the cytolytic effector. Activation and target cell lysis can also occur in the presence of antibodies to the TCR. This is accomplished by bridging the effector cell TCR to the target cell FcR by an anti-TCR monoclonal antibody (MoAb). Recent findings have placed the role of the FcR in this event in a questionable light. We confirm the importance of Fc gamma R by demonstrating that: (a) melanoma cells are killed by CTL clones in the presence of anti-TCR-CD3 antibodies only when the melanoma cells express the Fc gamma R on their surface; (b) native Ig, heat-aggregated Ig, or an Fc fragment from an antibody expressing the same isotype as the anti-TCR antibody can block the killing of high avidity Fc gamma RI-bearing cells mediated by anti-TCR antibody (F23.1); and (c) anti-Fc gamma R MoAb (2.4G2) and a truncated soluble Fc gamma RII molecule inhibit the killing of low-avidity Fc gamma RII-bearing cells mediated by anti-CD3 MoAb (145-2C11). Thus, we show that both high-avidity Fc gamma RI and low-avidity Fc gamma RII can mediate sideways killing depending upon the isotype of the anti-TCR antibody and the type of FcR present on the target cell surface.

Animals↗