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Biomedical subjects

R Haas

Publications and source records attributed to R Haas.

At least 19 recordsLinked to original sources
PubMed1992

Treatment of relapsed or refractory adult acute lymphocytic leukemia.

Sixty-six adult patients were treated for relapsing or refractory acute lymphocytic leukemia (ALL). The induction treatment consisted in a (1) first phase with vindesine 3 mg/m2 intravenously (IV) on days 1, 8, and 15; daunorubicin 45 mg/m2 IV on days 1, 8, and 15; erwinia-asparaginase 10,000 U/m2 IV on days 7, 8, 14, and 15; and prednisone 60 mg/m2 orally on days 1 to 21 and a (2) second phase with cytarabine 3000 mg/m2 as a 3-hour infusion two times a day on days 1 to 4 (in patients greater than 50 years of age we used 1000 mg/m2), and etoposide 100 mg/m2 IV on days 1 to 5. Side effects of induction Phase I were predominantly hematologic with subsequent infections. In Phase II, some patients additionally had gastrointestinal, cutaneous, ocular, and hepatic toxicity. Five patients died during Phase I and another died during Phase II. Five of these patients had T-cell ALL. Thirty-four (64%) of 54 patients in their first relapse had a complete remission (CR) with a median disease-free survival (DFS) of 2.9 months. The median overall survival (OAS) was 6.6 months. Seven of 12 patients with primary refractory disease, a second relapse, or relapse after bone marrow transplantation (BMT) had a CR. The CR rate and survival after first relapse was significantly better in patients with a preceding CR of more than 18 months compared with those with a shorter preceding remission. The leukocyte count was a second significant but not independent risk factor. There was a negative correlation between the leukocyte count and the duration of the preceding CR. The duration of the preceding CR was the major prognostic factor for survival in multivariate analysis. Twenty-two patients received BMT. None of nine patients with autologous BMT is alive and disease-free; 5 of 13 who underwent allogeneic BMT are. It was concluded that this treatment efficiently induced remission with tolerable toxicity. The remission duration should be improved by optimized consolidation treatment.

Adult↗
PubMed1992

Cloning and genetic characterization of a Helicobacter pylori flagellin gene.

Helicobacter pylori produces polar sheathed flagella, which are believed to be essential for the bacterial colonization of the human gastric mucosa. Here we report on the cloning and genetic characterization of a H. pylori gene encoding the subunit of the flagellar filament, the flagellin. Screening of a genomic library of H. pylori with an oligonucleotide probe derived from the N-terminal amino acid sequence of purified flagellin resulted in a recombinant plasmid clone carrying the flagellin-encoding gene flaA on a 9.3 kb Bg/II fragment. The nucleotide sequence of flaA revealed an open reading frame of 1530 nucleotides, encoding a protein with a predicted molecular mass of 53.2 kDa, which is similar in size with the purified flagellin protein in SDS-polyacrylamide gel electrophoresis. Sequence alignment of H. pylori flagellin (FlaA) with other bacterial flagellins demonstrates a high degree of similarity in the amino-terminal and carboxy-terminal regions, including those of the closely related genus Campylobacter (56% overall identity with Campylobacter coli flaA), but little homology in the central domain. Southern hybridizations of chromosomal DNA with flaA-specific probes did not reveal the presence of additional homologous flagellin genes in H. pylori. Sequence analysis of the flaA flanking regions and mapping of the flaA mRNA start site by a primer extension experiment indicated that transcription of the gene is under the control of a sigma 28-specific promoter sequence in H. pylori. The region upstream of the flaA promoter is subject to local DNA modification, resulting in the masking of two out of three closely linked HindIII restriction sites in the chromosome of strain 898-1. Escherichia coli strains harbouring the recombinant plasmid did not produce full-length flagellin and data obtained with FlaA fusion proteins using an E. coli plasmid expression system suggest that a distinct nucleotide sequence in the gene interferes with productive translation of this protein in E. coli.

Amino Acid Sequence↗
PubMed1992

Silent pilin genes of Neisseria gonorrhoeae MS11 and the occurrence of related hypervariant sequences among other gonococcal isolates.

Pilin variation in Neisseria gonorrhoeae depends on a family of variant genes that undergo homologous, intragenic recombination. This work focuses on the repertoire of silent variant pilin genes in strain MS11, which contribute to the extensive variation of the expressed gene copy. A total of 17 silent copies were identified, which are, to varying degrees, truncated at their 5' coding region and grouped in seven distinct pil loci. Most silent copies belong to loci pilS1, pilS2 and pilS6, which contain six, two and three silent copies, respectively, tandemly arranged. The pilS5 and pilS7 loci each contain only a single copy. In addition, two silent copies are associated with each of the two pilE loci. By comparison with sequences present in the expressed gene of other variants of the same strain, it is suggested that each silent locus is capable of donating variant sequences into the expression locus and, thus, each silent copy can contribute to the variability of pilin expression. Often, concomitant with changes in the expressed copy, the silent copies of the pilE1 locus undergo recombinations as well. Analyses of unrelated clinical isolates of N. gonorrhoeae reveal homologies of hypervariant pilin sequences with those present in strain MS11, suggesting a limited diversity of such sequences within the gonococcal population and the existence of substantial functional constraints on the variability of pilin and pili. The data further indicate that hypervariant pilin sequences are subject to horizontal exchange and interstrain recombination.

Bacterial Outer Membrane Proteins↗
PubMed1992

Interaction of two variable proteins (PilE and PilC) required for pilus-mediated adherence of Neisseria gonorrhoeae to human epithelial cells.

Pili confer the initial ability of Neisseria gonorrhoeae to bind to epithelial cells. Pilin (PilE), the major pilus subunit, and a minor protein termed PilC, reportedly essential for pilus biogenesis, undergo intra-strain phase and structural variation. We demonstrate here that at least two different adherence properties are associated with the gonococcal pili: one is specific for erythrocytes, which is virtually unaffected by PilE variation, and another is specific for epithelial cells, and is modulated in response to the variation of PilE. Based on this finding, mutants of a recA- strain were selected that had lost the ability to bind to human cornea epithelial cells (A-) but retained the ability to form pili (P+) and to agglutinate human erythrocytes (H+). The adherence-negative mutants failed to produce detectable levels of PilC1 or PilC2 proteins, representing piIC phase variants generated in the absence of RecA. The A- pilC phase variants were indistinguishable from their A+ parents and spontaneous A+ revertants with regard to the amount of PilE produced and its electrophoretic mobility, the degrees of piliation and haemagglutination, and the pilE nucleotide sequence. These data demonstrate a central role for PilC in pilus-mediated adherence of N. gonorrhoeae to human epithelial cells and further indicate that neither PilC1 nor PilC2 is obligatory for the assembly of gonococcal pili.

Amino Acid Sequence↗
PubMed1992

Production of Neisseria gonorrhoeae pili (fimbriae) in Pseudomonas aeruginosa.

Pseudomonas aeruginosa K/2PfS, when transformed with an expression plasmid harboring the pilin gene (pilE1) of Neisseria gonorrhoeae MS11, was able to express and assemble gonococcal pilin monomers into surface-associated pili, as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoblotting, and immunoelectron microscopy. Concomitant with the expression of gonococcal pili in P. aeruginosa was the virtual loss of production of P. aeruginosa K/2PfS pili normally associated with the host cell.

Amino Acid Sequence↗
PubMed1992

Thrombosis of difficult intracranial aneurysms by the endovascular placement of platinum-Dacron microcoils.

Patients with symptomatic aneurysms that are not excluded from the cerebral circulation have a poor prognosis. Standard treatment is surgical exploration with direct clipping of the aneurysm. Because of their large size or relationship to the base of the skull, some aneurysms may not be suitable for direct surgical clipping and may require alternative treatment modalities. A prospective clinical and radiological study of seven patients treated with the endovascular placement of platinum-Dacron microcoils to exclude the aneurysm from the cerebral circulation is reported. The seven patients ranged in age from 37 to 63 years; four were women. At completion of the endovascular procedure, total occlusion of the aneurysm with preservation of the parent artery had been achieved in four patients and 90% occlusion of the aneurysm in two. In the seventh patient, occlusion of the internal carotid artery resulted in the patient's death. At the 6-month follow-up review, both patients with an aneurysm less than 20 mm in size had persistent aneurysm thrombosis; however, the two patients with giant aneurysms had partial recanalization. Both required repeat thrombosis of their aneurysm with the placement of additional microcoils, one at 6 weeks and one at 6 months. These two patients have persistent aneurysm thrombosis at 12 months following their second procedure. The patient mortality rate for this study was 14%, while the procedure mortality/morbidity rate was 9%. It is concluded that thrombotic aneurysm therapy of difficult aneurysms is a safe procedure and will have a place in the treatment of selected aneurysms.

Adult↗
PubMed1992

Recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) subsequent to chemotherapy improves collection of blood stem cells for autografting in patients not eligible for bone marrow harvest.

Fourteen patients with relapsed Hodgkin's disease responded to a salvage therapy with Dexa-BEAM (dexamethasone, BCNU, etoposide, Ara-C and melphalan). In seven patients a continuous i.v. infusion with recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) was started subsequent to Dexa-BEAM (+rhGM-CSF) while the other seven patients received no hemopoietic growth factor (-rhGM-CSF). It was our objective to study the impact of rhGM-CSF on the collection of blood-derived hemopoietic stem cells in patients with extensive prior chemo- and radiotherapy not eligible for marrow harvest. Compared to baseline, we observed a significant increase of colony-forming units granulocyte-macrophage (CFU-GM) in the peripheral blood of patients receiving rhGM-CSF (p less than 0.05). On average, the yield of total nucleated cells and CFU-GM collected per single leukapheresis was 2.2 and 2.4-fold higher in the rhGM-CSF-treated patients respectively (p less than 0.05). With rhGM-CSF the interval from the start of chemotherapy to the end of blood stem cell collection could be reduced by 6 days (p less than 0.05). Following the CBV pretransplant regimen (cyclophosphamide, BCNU, etoposide), the reinfusion of rhGM-CSF-exposed stem cells resulted in a shorter time of leukocyte recovery (p less than 0.05). The number of CFU-GM/kg body weight transplanted was found to be predictive for the time of neutrophil recovery (p less than 0.05). In patients with bone marrow hypoplasia or fibrosis, rhGM-CSF as part of an effective salvage therapy improves the collection of blood stem cells that are capable of restoring hemopoiesis after high-dose pretransplant therapy.

Adult↗
PubMed1991

Etoposide in acute leukemia. Past experience and future perspectives.

Etoposide as a single agent is active in relapsed and refractory acute myelogenous leukemia (AML), with complete responses (CR) rates of 10% to 25%. The drug has been safely combined with cytarabine, azacytidine, vinca alkaloids, and anthracyclines, inducing remission rates of 20% to 60% in patients with previously treated AML. The experience with etoposide in acute lymphoblastic leukemia is less extensive, but the drug seems to be active in combination with cytarabine or aclacinomycin. In addition, etoposide is combined with cytarabine and anthracyclines for the primary treatment of AML. The response rates thus achieved are comparable with those obtained with standard regimens. A Phase I/II trial was initiated to study the efficacy of the NOVE combination (mitoxantrone [10 mg/m2/d, days 1 to 5] plus etoposide [100 mg/m2/d for 3, 4, or 5 days] in patients with refractory AML. The results showed that extended duration of etoposide administration is associated with higher CR rates. Overall, a CR rate of 43% was achieved in 61 patients. A sequential regimen with IDAC (idarubicin/cytarabine) and NOVE was designed for primary treatment of adult patients with AML. Cycles of IDAC or NOVE are applied depending on response. The results of the pilot study with this strategy were encouraging with 18 of 20 patients achieving CR. Further studies are under way to verify the efficacy of this strategy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

L-pilin variants of Neisseria gonorrhoeae MS11.

Phase- and antigenic variation of pilin expression in Neisseria gonorrhoeae is based on the genetic exchange between silent pilin genes (pilS) and the pilin expression locus (pilE). Similarly, the non-piliated L-variants of strain MS11, which show an increased resistance to certain antibiotics, are the result of recombination with the pilE locus. However, this recombination is atypical in that pilE(L) carries a tandem arrangement of a complete pilin gene and additional partial pilin genes under the control of the same pilE promoter. Since the two pilin gene copies are tandemly arranged and are often in the same translational frame, oversized pilin molecules are produced, which do not assemble into pili. The tandem gene copies introduced in a pilE(L) locus originate from silent loci where they are already joint. Upon reversion to the P+ phenotype the L-variants lose one pilin gene copy from the pilE(L) in a process reminiscent of the deletion events that otherwise lead to the formation of the non-revertible and non-piliated Pn mutants of MS11 gonococci. Thus deletion of pilin genes from pilE can be regarded as a third mechanism of pilin variation in gonococci.

Amino Acid Sequence↗
PubMed1991

Utilization of recombinant human GM-CSF to enhance peripheral progenitor cell yield for autologous transplantation.

Evidence has accumulated which indicates that efficacy of chemotherapy correlates with dose intensity and with total dose. For most cytotoxic agents, the major limiting factor for escalation of dose intensity is myelotoxicity. Attempts have been made to circumvent myelotoxicity by autologous bone marrow transplantation. Recently, it has been demonstrated that progenitors enriched from the peripheral blood can also be used successfully for autografting. The concentration of progenitor cells in peripheral blood is lower than that in bone marrow but myelosuppressive chemotherapy or hematopoietic growth factors, or a combination of both can be exploited to enhance the progenitor cell yield. The studies reported here are sequential. In the first study, eight patients with advanced Hodgkin's disease received myelosuppressive regimen consisting of cytarabine (100 mg/m2/12h SC days 1 to 5) and daunorubicin (45 mg/m2/d, days 3 and 4). Progenitor cell leukapheresis was performed during the rebound phase of hematopoiesis. All eight patients were treated with super-dose chemotherapy with progenitor cell transplantation. One patient died of CNS toxicity 48 days after transplantation but all other seven had sustained engraftment. In the second study, human recombinant GM-CSF (at 250 micrograms/m2/d as continuous infusion) was administered to twelve patients. Leukapheresis was started at a white blood count (WBC) of greater than 10 x 10(9)/L and the dosage of rhGM-CSF adjusted to keep the WBC between 10 x 10(9)/L and 20 x 10(9)/L. The median duration of rhGM-CSF application was 11.5 days and a median number of six leukaphereses performed. The median increase in the number of granulocyte-macrophage colony forming units (CFU-GM)/ml of peripheral blood was 8.5 fold.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Mitoxantrone/high-dose Ara-C and recombinant human GM-CSF in the treatment of refractory non-Hodgkin's lymphoma. A pilot study.

Previous study has shown that the combination of mitoxantrone (Novantrone, NO) and Ara-C (AC) (NOAC) was active in refractory non-Hodgkin's lymphoma (NHL) but myelosuppression was dose-limiting. In a pilot study, we investigated the effects of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) after NOAC chemotherapy in patients with refractory NHL. NO was applied at a dosage of 10 mg/m2/day on days 2 and 3 and AC at 3 g/m2/12h on days 1 and 2. RhGM-CSF was administered at 250 ug/m2/day as a continuous i.v. infusion from day 6 until the neutrophils were greater than 3.0/nl for 3 consecutive days. Twenty-three patients from five of the nine participating centers were treated with NOAC chemotherapy plus rhGM-CSF, whereas 14 patients from the other four centers received chemotherapy alone. With rhGM-CSF, the median duration of severe neutropenia (less than 0.5/nl) after NOAC was 8 days versus a median of 13 days without rhGM-CSF (P = 0.0058), and that of thrombocytopenia (less than 20.0/nl), 3 days versus 7 days (P greater than 0.4, NS). The rates of infections and stomatitis were 25% and 17%, respectively, for patients treated with rhGM-CSF as compared to 53% (P = 0.0547, NS) and 60% (P = 0.0078), respectively, without rhGM-CSF. The following side effects were associated with the administration of rhGM-CSF: pleural and/or pericardial effusions in five patients, thrombosis in two patients, bone pain in two patients, and respiratory distress syndrome in one patient. A complete remission was achieved in nine of the 23 patients treated with NOAC plus rhGM-CSF, and in two of the 14 patients treated with chemotherapy alone. The median survival of patients treated with rhGM-CSF was not reached at 400 days and seemed to be longer than that of patients treated with chemotherapy alone (median, 109 days; P = 0.036). RhGM-CSF after chemotherapy can be applied safely to patients with NHL, shorten the period of severe cytopenia, reduce the rates of stomatitis, and did not seem to cause adverse effects on response.

Adolescent↗
PubMed1990

Activation of lymphocytes induced by recombinant human granulocyte-macrophage colony-stimulating factor in patients with malignant lymphoma.

To investigate effects of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) on lymphoid cells in vivo, we monitored changes in absolute lymphocyte counts, plasma concentrations of soluble interleukin-2 receptor (sIL-2R) and soluble cytotoxic/suppressor (sCD8) antigens, and phenotypic changes of surface membrane antigens of peripheral mononuclear cells from 14 patients with malignant lymphoma treated with rhGM-CSF. Eight of the 14 patients had relapsed or had refractory non-Hodgkin's lymphoma (NHL) and received rhGM-CSF after intensive chemotherapy with novantrone (NO) and high-dose Ara-C (AC) (NOAC) as salvage regimen. Six other patients with NHL or Hodgkin's disease (HD) were in complete remission and treated with rhGM-CSF to enhance peripheral hematopoietic progenitor cell harvest for autografting. An increase in absolute lymphocyte count at the zenith of leukocyte elevation and a drastic increase in concentration of sIL-2R from a median of 565 U/mL to 6,700 U/mL on rhGM-CSF infusion were found in all patients. There was also a moderate increase in sCD8 levels from a median of 277 U/mL to 470 U/mL. Ten patients were available for serial studies of phenotypic changes in surface membrane antigens. A significant increase in CD25+ (IL-2R+) (P = .0020) and CD4+ (P = .0137) lymphocytes was observed in all patients, but no significant change in CD3+, CD8+, TCR delta 1+, or CD19+ cells. Elevations in absolute lymphocyte counts or in concentrations of sIL-2R or sCD8 were not observed in four other patients during recovery from intensive chemotherapy without rhGM-CSF support. Our results provide evidence that administration of rhGM-CSF might activate lymphocytes in vivo. The impact of this activation on the remission rate and duration, as well as survival in patients with NHL, warrants further investigation.

Antigens, CD↗
PubMed1990

Molecular analysis of periodontal pathogens.

Both Bacteroides gingivalis and Actinobacillus actinomycetemcomitans have been implicated in the destruction of periodontal tissues. To understand better the role putative virulence factors from the two bacterial species may play in an infection, the collagenase gene from Bact. gingivalis and the leucotoxin gene from A. actinomycetemcomitans were cloned. As it is intended to generate strains carrying defined mutations in these genes for in vitro and in vivo experiments, extensive restriction mapping and sequence analyses of these clones are being undertaken. Furthermore a conjugation system for Bact. gingivalis and A. actinomycetemcomitans will be established.

Actinobacillus↗
PubMed1990

Phagocytic response modifying reactivity of enzymatic cell wall digests of Nocardia opaca.

Aqueous extracts (ENOCW) and enzymatic digests of purified Nocardia opaca cell wall fragments, virtually free of muramyl peptides, were monitored for their phagocytic response modifying reactivity on polymorphonuclear leucocytes, separated or unseparated in whole human blood. In the presence of ENOCW a 74% increased production of superoxide during the respiratory burst of TPA-activated polymorphonuclear leukocytes was observed, as compared to the unprimed control. Delipidation of this preparation resulted in a further increase in reactivity (144%). Even in the presence of whole human blood, as a model for competitive binding in biological fluids, an enhanced generation of superoxide by TPA activated blood phagocytes remained detectable. A 37-75% decreased phagocytic reactivity in samples of HIV-seropositive blood was considerably restored in the presence of ENOCW.

Acridines↗