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Biomedical subjects

C Huber

Publications and source records attributed to C Huber.

At least 127 records · Page 7Linked to original sources

Lytic susceptibility of target cells to cytotoxic T cells is determined by their constitutive major histocompatibility complex class I antigen expression and cytokine-induced activation status.

Cytotoxic T-cell lines (TCL) were raised in vitro using stimulator cells with a defined major histocompatibility complex (MHC) mismatch and tested in a cytotoxic chromium-release assay against haemopoietic and non-haemopoietic target cells from the original stimulator. Monoclonal antibody (mAb)-blocking experiments and simultaneous determination of MHC class I, class II, lymphocyte function-associated antigen-1 (LFA-1) and intracellular adhesion molecule-1 (ICAM-1) density by quantitative radioimmunometric methods and flow cytometry on target cells demonstrated that lysis was restricted by MHC class I and dependent upon the constitutive MHC class I antigen expression. Measurements showed a high constitutive expression of class I MHC antigens on peripheral blood mononuclear cells (PBMC), but a low one on keratinocytes (K). Also, PBMC were more susceptible to lysis by TCL than K. Interferon-gamma (IFN-gamma) treatment of K resulted in increased MHC class I antigen expression and enhanced lytic susceptibility to TCL. IFN-alpha and tumour necrosis factor-alpha (TNF-alpha) treatment, which did not modulate MHC class I antigen expression on K, did not influence the amount of K lysis either. None of the cytokines tested in this analysis, however, increased the expression of MHC class I, class II, ICAM-1 and LFA-1 on PBMC. Only IFN-gamma pretreatment showed a minimal, statistically significant increase in MHC class I antigen expression. In spite of the minimal effect of IFN-gamma and no effect of IFN-alpha on class I MHC expression, pretreatment of target cells with both cytokines considerably increased their lytic susceptibility. The mechanism of cytokine-induced enhanced lytic susceptibility to TCL was not explained by increased MHC class I, LFA-1 or ICAM-1 expression, since no correlation was found between surface expression of these molecules and lytic susceptibility to TCL. These data demonstrate that: (1) the constitutive density of MHC class I antigens determines the extent of TCL lysis; (2) IFN-gamma, and not IFN-alpha or TNF-alpha controls the amount of K target cell lysis by increasing their MHC class I antigen expression; and (3) IFN-gamma and IFN-alpha control the amount of PBMC target cell lysis by a mechanism independent of MHC class I, ICAM-1 or LFA-1 expression.

Cell Adhesion Molecules

Clozapine promotes approach-oriented behavior in male mice.

Clozapine, an atypical antipsychotic agent, exerts ameliorative effects upon negative symptoms, but to date, its mechanism of action is poorly understood. We employed ethological methods to study the effects of clozapine, given 1 hour beforehand, on the social responses of (1) an individually housed male mouse exposed to an equally "matched" aggressive male opponent and (2) a group-housed "intruder" mouse exposed to an isolated, aggressive male. Encounters lasted 6 minutes. In matched pairs, mice given clozapine (0.01, 0.03, or 0.1 mg/kg s.c.) showed a significant increase in aggression without signs of stimulation. When given to intruder mice, clozapine (0.03, 0.1, or 0.3 mg/kg p.o.) markedly reduced defensive behavior and reinstated their investigative and sexual activities. The results suggest that low, nonsedating doses of clozapine counteract social withdrawal by selectively increasing "situationally appropriate" approach behavior.

Aggression

Intravenous immune globulin in chronic lymphocytic leukaemia.

The most common complication of chronic lymphocytic leukaemia (CLL) is infection, which occurs mainly in advanced stages of disease or in those patients with hypogammaglobulinaemia. Intravenous immune globulin (IVIG) has been shown to be a useful prophylactic therapy against infections in such patients. A randomized, double-blind study on 36 patients receiving either 500 mg/kg or 250 mg/kg IVIG every 4 weeks was undertaken to determine the dose regimen required. There was no significant difference in the two treatment groups and we found that CLL patients were equally protected with low-dose IVIG.

Agammaglobulinemia

[Sound frequency analysis for identification of venous air embolism].

Air emboli occurring during surgery are considered to be life-threatening incidents. With the aim of achieving acoustic identification of venous air emboli, a frequency analysis of the sounds induced by an air embolism (millwheel murmurs) as well as of all other unusual sounds, was undertaken during 20 operations, and in experiments with animals. The frequency spectra of the sounds induced by air emboli are characterised by an increase in the amplitudes in the frequency range 1,100 to 3,000 Hz, while the amplitudes of normal heart sounds continuously decrease with increasing frequency. The frequency spectrum was examined for characteristics using an electronic filter system. The sounds induced by air emboli can be clearly distinguished from normal heart sounds. During operations on patients, suction sounds occur, the frequency patterns of which are not easy to distinguish from those of embolus-induced sounds, although an acoustic distinction can be made via a stethoscope or a loudspeaker. With optimal adjustment of the filter system, 73 out of 81 (90%) embolism-related sounds were correctly identified in animal experiments. On no occasion were normal heart sounds wrongly identified as due to an embolus. However, an embolus sound was frequently mimicked by interfering sounds such as those produced by artificial respiration, and other ambiend sounds. By modifying the oesophageal catheter to achieve optimal suppression of interfering sounds, this filter system could be developed into an alarm.

Animals

Activity of P-glycoprotein in B-cell chronic lymphocytic leukemia determined by a flow cytometric assay.

BACKGROUND: Chemoresistance in some hematologic malignancies has been associated with overexpression of P-glycoprotein, which is encoded by the MDR1 gene (also known as PGY1). However, inconsistencies in data on frequency and clinical relevance of multidrug resistance in B-cell chronic lymphocytic leukemia (B-CLL) may reflect a need for improved techniques to detect this overexpression. PURPOSE: Our purpose was to measure P-glycoprotein activity in peripheral blood cells of B-CLL patients and to analyze possible clinical correlations (disease duration, prior treatment, Rai disease stage, lymphocyte counts, and disease progression). METHODS: P-glycoprotein activity was assayed in peripheral blood cells of 42 consecutive B-CLL patients (22 treated and 20 untreated). We used dual fluorescence in a flow cytometric assay that detects efflux of the fluorescent dye rhodamine 123, which is transported from the cell by the P-glyprotein pump. Leukemia cells were costained with monoclonal antibody Leu12/CD19, and rhodamine 123 efflux was measured. Expression of MDR1 and MDR3 (also known as PGY3) messenger RNA (mRNA) was quantitatively evaluated by polymerase chain reaction (PCR) in 26 cases. RESULTS: Marked rhodamine 123 efflux was observed in 34 (81%) of the 42 cases and was abolished in the presence of multidrug resistance inhibitors. Rhodamine 123 efflux was not associated with Rai stage, lymphocyte counts, duration of disease, or disease progression. Although rhodamine 123-negative cases were about equally distributed among untreated and previously treated patients, the percentage of cells with rhodamine 123 efflux was significantly lower for untreated patients than for those treated with chemotherapy regimens including at least one multidrug resistance-associated drug. MDR1 mRNA was detected in 25 of 26 cases and MDR3 mRNA in all 26. MDR1 mRNA expression was significantly correlated with rhodamine 123 efflux, whereas MDR3 mRNA expression was not significantly correlated; MDR1 and MDR3 mRNA expression was not significantly associated with Rai stage, prior treatment, or disease progresssion. CONCLUSIONS: These findings suggest that P-glycoprotein overexpression in B-CLL is intrinsic rather than acquired and that P-glycoprotein activity is enhanced after exposure to multidrug resistance-associated drugs. This enhanced activity does not seem to be associated with more aggressive disease. Our results also indicate that an assay of P-glycoprotein function combined with PCR is suitable for clinical multidrug resistance screening. IMPLICATIONS: Additional studies are needed to determine whether functional activity of P-glycoprotein, measured by rhodamine 123 efflux, is directly related to clinical drug resistance.

ATP Binding Cassette Transporter, Subfamily B, Mem

Type-I interferons are potent inhibitors of interleukin-8 production in hematopoietic and bone marrow stromal cells.

Interleukin-8 (IL-8) is produced by many cell types upon stimulation with bacterial products or inflammation-associated cytokines such as tumor necrosis factor-alpha and IL-1. Interferons (IFNs) represent another group of cytokines that are induced by similar stimuli in inflammatory reactions. We show now that type-I IFNs are potent inhibitors of IL-8 expression in vitro and in vivo. A significant reduction of both secretion of IL-8 protein and accumulation of IL-8 mRNA in vitro was observed in several cell types comprising peripheral blood mononuclear cells (PBMNC) from healthy donors and from patients with chronic myelogenous leukemia (CML), the myelomonocytic cell line THP-1, and bone marrow (BM) stromal cells as a representative model for BM microenvironment. By contrast, in lipopolysaccharide-stimulated polymorphonuclear phagocytes IFN failed to suppress IL-8 expression. In untreated patients with CML, a constitutive expression of IL-8 mRNA was detected in freshly isolated PBMNC that was markedly reduced 5 hours after therapeutic application of IFN-alpha. The mechanism of IL-8 downregulation was studied more in detail in the THP-1 cell line. The experiments showed that de novo protein synthesis was not required for the inhibitory effect. RNA decay analysis and nuclear run-on assays suggest that in THP-1 cell line the inhibition of IL-8 expression is predominantly regulated at the posttranscriptional level.

Bone Marrow

Induction of circulating IL-1 receptor antagonist by IFN treatment.

This study was undertaken to determine whether IFN induce IL-1 receptor antagonist (IL-1Ra), a specific inhibitor of IL-1. Plasma samples were obtained from healthy volunteers (n = 5) and patients with chronic hepatitis C (n = 5) treated with IFN-alpha, and from patients with renal cell carcinoma (n = 6) treated with IFN-gamma and assayed for IL-1Ra by a specific radioimmunoassay. Both types of IFN were administered subcutaneously. In vitro studies were carried out with PBMC from healthy volunteers. A single, low and nontoxic dose (1 x 10(6) U) of IFN-alpha induced circulating IL-1Ra, which reached peak levels within 12 h. This effect was dose-dependent and more pronounced with a higher dose (5 x 10(6) U). Peak IL-1Ra levels 12 h after 5 x 10(6) U IFN-alpha were 4.16 +/- 0.35 ng/ml in healthy volunteers and 5.7 +/- 0.73 ng/ml in patients with chronic hepatitis C (difference not significant). Thereafter levels declined but remained elevated for 24 h. IFN-gamma treatment led only to a modest increase of circulating IL-1Ra even at a dose of 400 micrograms; this dose, however, was associated with side effects similar to those seen after injection of 5 x 10(6) U IFN-alpha. PBMC stimulated with IFN-alpha or IFN-gamma produced IL-1Ra in vitro. The induction of IL-1Ra may contribute to the antiviral, anti-inflammatory, and antiproliferative effects of IFN.

Carcinoma, Renal Cell

The human immunoglobulin kappa locus. Characterization of the partially duplicated L regions.

The L regions are parts of the C kappa proximal (p) and distal (d) copies of the human immunoglobulin kappa locus and are therefore called the Lp and Ld regions. The two regions with their 25 V kappa genes and pseudogenes have now been cloned, thus completing the cloning of the kappa locus. Lp has been linked to the neighboring Ap and B regions, while Ld was linked to Ad. There is good evidence that at the other side of Ld, i.e. towards the centromere, the end of the locus has been reached. Most of the cloning and linking was achieved by chromosomal walking, employing cosmid and phage lambda clones. No such clones could be found for three small gaps. Two of them were closed by a polymerase chain reaction strategy; the third one was characterized by genomic blot hybridization experiments and eventually bridged by a yeast artificial chromosome clone. Early in evolution, a stretch of about 25 kb which comprised three V kappa genes near the 5' end of the L region precursor must have been duplicated, such that the later duplication of large parts of the kappa locus resulted in the appearance of two very similar three-gene regions in each, Lp and Ld. Two deletions in the central parts of the L regions, on the other hand, must have occurred after the duplication of the locus, since they are found in Lp and Ld in different positions.

Base Sequence

The V kappa genes of the L regions and the repertoire of V kappa gene sequences in the human germ line.

Only 14 of the 25 V kappa genes and pseudogenes had been found before as parts of the L regions. The cloning and linking described in the accompanying report allowed us now to assign to Lp or Ld some V kappa genes which had been found before on scattered clones. In addition the sequences of several still unknown genes are reported here, thus completing the publication of the V kappa genes of the kappa locus as far as they are potentially functional or have only one or two 1-bp defects. Of the V kappa genes of the kappa locus, 32 are potentially functional, 16 have minor defects, 3 have both potentially functional and slightly defective alleles and 25 are pseudogenes which amounts to a repertoire of 76 V kappa-related gene sequences. The V kappa genes of the L regions are, within the subgroups, particularly similar to each other, which is in part due to common evolutionary origins and in part caused by gene conversion-like events. One donor-acceptor pair could be clearly identified, since converted and not-converted alleles of the acceptor gene were found. In other cases the duplicates of the converted genes served as non-converted controls.

Alleles

Capillary zone electrophoresis of p-aminobenzoic acid derivatives of aldoses, ketoses and uronic acids.

Aldoses, ketoses and uronic acids were derivatized with p-aminobenzoic acid and separated as their borate complexes by capillary zone electrophoresis, using a capillary tube of fused silica containing 150 mM borate buffer, pH 10.0, as carrier. The electrophoretic mobilities of 22 carbohydrates were determined and found to increase with increasing stability of the borate complexes formed. Besides the number of hydroxyl groups and the presence of substituents, complex stability depended most strongly on the configuration of the three vicinal hydroxyl groups at C2, C3 and C4. On-column UV monitoring at 285 nm allowed the detection of glucose with a lower mass detection limit of 15 fmol and a concentration sensitivity of 4 microM. Reproducible quantification of carbohydrates was achieved at least in the concentration range of 0.1-10 mM in reaction solutions by the relative peak area method, using cinnamic acid as internal standard. The method was applied successfully to the determination of the monosaccharide composition of polysaccharides extracted from Radix althaeae.

4-Aminobenzoic Acid

The CD8 alpha locus is located on the telomere side of the immunoglobulin kappa locus at a distance of 2 Mb.

The immunoglobulin kappa and CD8 alpha loci had been mapped by in situ hybridization to the short arm of chromosome 2 at 2cen-p11.2 and 2p1, respectively, but probes derived from the two loci did not hybridize to the same large PFGE fragments. We have now succeeded in linking the two loci on a 3.0-Mb fragment from a partial NruI digest. A new hybridization probe located between the two loci provided additional linking fragments and allowed the distance to be determined as 2.0-2.2 Mb.

CD8 Antigens

Aggressive chemotherapy combined with G-CSF and maintenance therapy with interleukin-2 for patients with advanced myelodysplastic syndrome, subacute or secondary acute myeloid leukemia--initial results.

Aggressive chemotherapy of advanced myelodysplastic syndrome (MDS), acute myeloid leukemia (AML) evolving from MDS, subacute AML and secondary AML has usually been associated with low complete remission (CR) rates, a high incidence of early death, and low disease-free survival. We therefore have initiated a phase-III trial of aggressive chemotherapy consisting of idarubicin, cytosine arabinoside, and VP-16 to improve the CR rate. Each chemotherapy cycle is followed by G-CSF to accelerate neutrophil recovery and to reduce the incidence of infections. Until now, 19 patients with high-risk AML have been entered. The CR rate is 47%, with only one death during induction. Patients achieving CR are randomized to receive either high-dose or low-dose interleukin-2 to eliminate residual leukemic cells and to prolong the duration of remission.

Adult

IL-2, IL-3, and IFN-gamma differently affect in vivo frequencies of circulating precursors of cytotoxic T lymphocytes (CTL-P).

Experimental animal and human in vivo studies have previously demonstrated the impact of exogenous administration of various cytokines on frequencies of circulating myeloid and LAK precursor cells. For the first time we investigated whether exogenous cytokines, in the absence of antigenic challenge, may also influence frequencies of circulating antigen-specific cytotoxic T-lymphocyte precursor cells. We further asked whether triggering of autoimmune pathways as has been reported for several cytokines can be confirmed on the cellular level by demonstration of induction of autoreactive CTL-p. Limiting dilution analysis was used to determine alloreactive CTL-p frequencies in 31 patients with nonhematologic diseases before and after short-term systemic treatment with either rIL-2 (4.8 x 10(6) IU/m2 bid), rIL-3 (2.5, 5.0 or 10.0 micrograms/kg qd), rGM-CSF (5 micrograms/kg qd), rIFN-gamma (200 or 400 micrograms qd), or IFN-alpha (3 or 5 x 10(6) IU qod). Simultaneously, autoreactive CTL-p frequencies were determined by split-well analysis in 25 of these patients. We found that rIL-2 significantly expands the circulating precursor pool of alloreactive CTL (p < 0.05). rIL-3 affected CTL-p frequencies in a dose-dependent fashion. Low and intermediate doses of rIL-3 did not exhibit significant effects, whereas 10 micrograms/kg rIL-3 led to expansion of alloreactive CTL-p in the same order of magnitude as did rIL-2. This effect was statistically significant when compared with rGM-CSF (p < 0.02), which apparently had no influence on alloreactive CTL-p frequencies. In contrast to rIL-2 and rIL-3, exogenous rIFN-gamma markedly reduced the circulating precursor pool of CTL. This again was statistically significant compared with rIFN-alpha (p < 0.03), which, like rGM-CSF, did not exhibit any effects on the level of alloreactive CTL-p. Frequencies of autoreactive CTL-p were invariably below the limit of detection in our system (< 1/300,000). In conclusion, these data demonstrate that (a) short-term systemic administration of rIL-2, rIL-3, and rIFN-gamma differently affects the clone size of circulating precursors of alloreactive CTL in man, while rGM-CSF and rIFN-alpha do not exhibit measurable effects, and (b) none of the cytokines administered is capable of uncovering detectable frequencies of autoreactive CTL-p.

Autoimmunity

Treatment of 11 patients with chronic myelogenous leukemia with interferon-alpha-2C and low-dose cytosine arabinoside.

Patients with Philadelphia (Ph) chromosome-positive chronic myelogenous leukemia (CML) and on interferon (IFN)-alpha-2c treatment for at least two months were entered in the present pilot study. IFN-alpha treatment was maintained identically and cytosine arabinoside (Ara-C) was added at monthly cycles of 10 mg/m2/day for ten days subcutaneously. In the case of a leukocyte nadir above 10 G/l, the Ara-C dose was increased to 20 mg/m2/day for 10 days per month. Ten of the eleven patients entered in this study were evaluable for toxicity and response. They received a total of 87 IFN-alpha/Ara-C cycles (3-14/patient). Five patients received 1-5 cycles with Ara-C dose intensification to 20 mg/m2/day. The following gastrointestinal and hematological toxicities were attributable to Ara-C, as they had not been observed in these patients during the preceding IFN-alpha monotherapy period. Gastrointestinal side effects consisted of nausea grade 1 (n = 5) and diarrhea grade 2 (n = 1). Hematotoxicity was observed in eight patients, grade 1 in five patients and grades 2, 3 and 4 in one of the patients each. Both episodes of grades 3 and 4 toxicity were seen during dose escalation to 20 mg/m2. Small cytogenetic responses (4-14%) were observed in 3 patients and a larger one (50%) in one patient, hematological improvement or stable disease in an additional three patients. These preliminary data suggest that the combination of IFN-alpha and low-dose Ara-C is active in inducing cytogenetic responses in CML patients at an acceptable rate of toxicity and therefore warrant further investigation.

Adult

Immune response modulation by pentoxifylline in vitro.

Pentoxifylline (PTX) has recently been shown to modulate TNF-alpha production and to reduce the incidence and severity of all major complications after BMT, including mucositis, veno-occlusive disease, renal insufficiency, hypertension, and graft-versus-host disease. To analyze in detail the effect of PTX on immune complications after BMT, we investigated the immunomodulatory effect of PTX on immune responses in vitro. The continuous presence of PTX significantly reduced the proliferative response of PBMC to PHA stimulation and to alloantigens in a dose-dependent manner. Starting at concentrations of 100 micrograms/ml, PTX was able to inhibit and, at 1000 micrograms/ml, completely block mitogen-induced proliferation. Maximal inhibition of more than 90% (91 +/- 4%) was also observed at PTX concentrations of 1000 micrograms/ml in the mixed lymphocyte culture (MLR) and by addition on day 0. However, lower but still significant suppression (13 +/- 7%) was achieved at concentrations of 10 micrograms/ml PTX. The inhibitory capacity of PTX was increased by mAbs against TNF-alpha (34 +/- 5% additional suppression at 100 micrograms/ml PTX) and not reversed by the addition of rTNF-alpha. The effect of PTX on the generation of CTLs in vitro was studied in the cell-mediated lymphotoxicity assay. PTX (100 micrograms/ml) significantly inhibited (P = 0.0178) the in vitro generation of CTLs when PTX was added to the culture on day 0. PTX also showed profound modulatory properties in the NK assay, with a reduction of 23 +/- 3% in specific lysis at 10 micrograms/ml PTX and maximal reductions of 88 +/- 3% at 1000 micrograms/ml PTX. Immunomodulatory properties of PTX were not only associated with blockage of TNF-alpha, as shown by decreased mRNA expression and TNF-alpha values in the culture supernatants, but also with an impaired production of other cytokines and secondary messages such as IFN-gamma and neopterin. PTX treatment, however, did not affect IFN-alpha or IL-1 beta production, and IL-6 release was even increased. PTX, therefore, has profound immunomodulatory properties in vitro, which are associated with selective inhibition of cytokine release and can be enhanced by the addition of mAbs against TNF-alpha, but not reversed by the addition of rTNF-alpha.

Biopterins

Cytokine therapy of neoplastic and inflammatory disease.

Cytokines have been widely tested in clinical trials during recent years and beneficial responses have been observed in a variety of malignant, infectious and autoimmune diseases. Interferon-alpha induces remissions in patients with certain hematological malignancies such as hairy cell leukemia and chronic myelogenous leukemia. A proportion of patients with chronic viral hepatitis is cured upon application of interferon-alpha. Treatment with interferon-gamma reduces the number of infections in patients with chronic granulomatous disease. In addition, several chronic infections with intracellular pathogens also respond to treatment with this cytokine. With the exception of some patients with renal cell carcinoma and malignant melanoma, solid tumors are largely resistant to administration of these cytokines. Cytokine treatment has changed the outlook for a small group of patients with selected chronic diseases. However, clinical experience with cytokines is still limited and only interferons have been tested for treatment of a variety of diseases. Thus, it seems reasonable to expect that more cytokine-responsive diseases might be identified by continued research efforts.

Cytokines