Biomedical subjects

R Haas

Publications and source records attributed to R Haas.

At least 37 records · Page 2Linked to original sources

PubMed2001

Markers for carcinogenicity among butadiene-polymer workers in China.

We examined a spectrum of genotoxic and other outcomes in 41 butadiene-polymer production workers and 38 nonexposed controls, in China, to explore the role of butadiene in human carcinogenesis. Among butadiene-exposed workers, median air exposure was 2 ppm (6-h TWA), due largely to intermittent high-level exposures. Compared to unexposed subjects, butadiene-exposed workers had greater levels of hemoglobin N-(2,3,4-trihydroxybutyl)valine (THBVal) adducts (P<0.0001), and adduct levels tended to correlate, among butadiene-exposed workers, with air measures (P=0.03). Butadiene-exposed workers did not differ, however, from unexposed workers with respect to frequency of uninduced or diepoxybutane-induced sister chromatid exchanges, aneuploidy as measured by fluorescence in situ hybridization of chromosomes 1, 7, 8 and 12, glycophorin A variants or lymphocyte hprt somatic mutation. Also among the exposed, greater THBVal levels were not associated with increases in uninduced sister chromatid exchanges, aneuploidy, glycophorin A, or hprt mutations. Butadiene-exposed workers had greater lymphocyte (P=0.002) and platelet counts (P=0.07) and lymphocytes as a percent of white blood cells were moderately correlated with greater THBVal levels (Spearman's rho=0.32, P=0.07). Among butadiene-exposed workers, several serum cytokines correlated with THBVal adduct levels. Overall, the study demonstrated exposure to butadiene in these workers, by a variety of short-term and long-term measures, but did not show specific genotoxic effects, at the chromosomal or gene levels, related to that exposure.

Air Pollutants, Occupational↗

PubMed2001

Outpatient treatment of multiple myeloma with a combination of vincristine, Adriamycin and dexamethasone.

Patients with relapsed multiple myeloma (MM) have been shown to respond to a combination therapy consisting of vincristine, Adriamycin (doxorubicin) and high-dose dexamethasone (VAD). Because of the low hematological toxicity of the VAD regimen, this combination is frequently chosen for tumor reduction prior to high-dose therapy and blood stem cell transplantation. This study was designed to examine the efficacy and complications of outpatient VAD treatment. Over a period of 6 years, 103 outpatients with MM were treated with VAD chemotherapy administered by microprocessor-controlled infusion pumps via intravenous polyurethane catheters equipped with a safety valve. Response to treatment, treatment-associated complications and infections were documented and analyzed. In 85 of the 103 patients, tumor reduction by more than 25% was found. In 8 patients an occlusion occurred as a result of kinking of the central venous catheter in the subcutaneous segment. In two treatment cycles the infusions had to be stopped because of irreversible catheter occlusion. Twenty patients were hospitalized because of complications, which were infectious in 12 and noninfectious in 8. Severe infectious complications (> or =WHO grade III) occurred in 5.6% of the treatment cycles. Thus, continuous infusion of VAD over 96 h can be performed on an outpatient basis with a low complication rate.

Adult↗

PubMed2001

Combining G-CSF with a blockade of adhesion strongly improves the reconstitutive capacity of mobilized hematopoietic progenitor cells.

OBJECTIVE: Mobilization of hematopoietic progenitor cells is achieved mainly by application of growth factors and, more recently, by blockade of adhesion. In this report, we describe the advantages of a combined treatment with granulocyte colony-stimulating factor (G-CSF) and anti-VLA4 (CD49d)/anti-CD44 as compared to treatment with the individual components. MATERIALS AND METHODS: Mobilization by intravenous injection of anti-CD44, anti-VLA4, or G-CSF was controlled in spleen and bone marrow with regard to frequencies of multipotential colony-forming unit (C-CFU), marrow repopulating ability, long-term reconstitution, recovery of myelopoiesis, and regain of immunocompetence. RESULTS: Mobilization by anti-CD44 had a strong effect on expansion of early progenitor cells in the bone marrow, while the recovery in the spleen was poor. In anti-CD49d-mobilized noncommitted and committed progenitors, progenitor expansion was less pronounced, but settlement in the spleen was quite efficient. Thus, anti-CD44 and anti-CD49d differently influenced mobilization. Accordingly, mobilization and recovery after transfer were improved by combining anti-CD44 with anti-CD49d treatment. Mobilization by G-CSF was most efficient with respect to recovery of progenitor cells in the spleen. However, when transferring G-CSF-mobilized cells, regain of immunocompetence was strongly delayed. This disadvantage could be overridden when progenitor cells were mobilized via blockade of adhesion and when expansion of these mobilized progenitor cells was supported by low-dose G-CSF only during the last 24 hours before transfer. CONCLUSION: Mobilization of pluripotent progenitor cells via antibody blockade of CD44 or CD49d or via G-CSF relies on distinct mechanisms. Therefore, the reconstitutive capacity of a transplant can be significantly improved by mobilization regimens combining antibody with low-dose G-CSF treatment.

Animals↗

PubMed2001

Tandem high-dose chemotherapy in high-risk primary breast cancer: a multivariate analysis and a matched-pair comparison with standard-dose chemotherapy.

Stem cell-supported high-dose chemotherapy (HDCT) is currently being evaluated in patients with high-risk primary breast cancer (HRPBC), as defined by extensive axillary lymph node involvement. Conclusive results from randomized studies with sufficient patient numbers and follow-up are pending. We retrospectively analyzed 144 HRPBC patients enrolled in a single-arm trial of tandem HDCT at the University of Heidelberg to evaluate the prognostic value of nodal ratio, HER2/neu status, and cytokeratin-positive bone marrow cells and to compare the outcomes of these patients with those of a conventionally treated control group of 91 patients matched by nodal ratio, tumor size, combined hormone-receptor status, and HER2/neu status. The tandem HDCT regimen consisted of 2 cycles of induction chemotherapy followed by 2 cycles of blood stem cell-supported high-dose ifosfamide, 12 g/m2; carboplatin, 900 mg/M2; and epirubicin, 180 mg/m2. Conventionally treated patients received a regimen containing anthracycline without taxanes (52 patients) or CMF (cyclophosphamide, methotrexate, and 5-flurouracil; 39 patients). With a median follow-up of 3.8 years, disease-free, distant disease-free, and overall survival rates were 62%, 65%, and 84%, respectively. In univariate analysis, besides the hormone receptor status (P = .007), HER2/neu overexpression was the strongest predictor of earlier death (P = .017). In multivariate analysis, a nodal ratio of > or =0.8 was found to be the only independent predictor of relapse (relative risk [RR] = 2.09; 95% confidence interval [CI], 1.21-3.60; P = .008) and only the absence of hormone receptors was associated with earlier death (RR = 3.59; 95% CI, 1.45-8.86; P = .006). Despite a trend toward later distant relapse after HDCT compared with standard-dose chemotherapy with a median follow-up of 3 years (P = .059), thus far, matched-pair analysis has not demonstrated significantly better survival rates after HDCT in all matched patients (P = .786) or in the subgroups of anthracycline-treated patients and patients with and without overexpression of HER2/neu. So far, the follow-up time has been too short to draw definite conclusions; however, patients with a nodal ratio of > or =0.8, receptor-negative tumors, or HER2/neu overexpression are at high risk for relapse and death, irrespective of the kind of adjuvant chemotherapy.

Adolescent↗

PubMed2001

Lethal photosensitization for decontamination of implant surfaces in the treatment of peri-implantitis.

Peri-implantitis is considered to be a multifactorial process involving bacterial contamination of the implant surface. A previous study demonstrated that a combination of toluidine blue O (100 microgram/ml) and irradiation with a diode soft laser with a wavelength of 905 nm results in an elimination of Porphyromonas gingivalis (P. gingivalis), Prevotella intermedia (P. intermedia), and Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) on different implant surfaces (machined, plasma-flame-sprayed, etched, hydroxyapatite-coated). The aim of this study was to examine the laser effect in vivo. In 15 patients with IMZ implants who showed clinical and radiographic signs of peri-implantitis, toluidine blue O was applied to the implant surface for 1 min and the surface was then irradiated with a diode soft laser with a wavelength of 690 nm for 60 s. Bacterial samples were taken before and after application of the dye and after lasing. The cultures were evaluated semiquantitatively for A. actinomycetemcomitans, P. gingivalis, and P. intermedia. It was found that the combined treatment reduced the bacterial counts by 2 log steps on average. The application of TBO and laser resulted in a significant reduction (P<0.0001) of the initial values in all 3 groups of bacteria. Complete elimination of bacteria was not achieved.

Adult↗

PubMed2001

Bicortical titanium screws for critical orthodontic anchorage in the mandible: a preliminary report on clinical applications.

Critical anchorage during orthodontic treatment in the mandible needs both time and effort and patient compliance. In 8 patients, 12 bicortical titanium screws (BIS) were used as anchorage units for orthodontic molar protraction. The criteria for patient selection were: critical anchorage in the lower jaw (i.e. retraction of anterior teeth undesirable) and molar extraction sites. After insertion of the screws in local anesthesia, orthodontic forces were applied immediately. One screw worked loose and had to be removed before the end of treatment. Problems encountered included impingement of the screw head and slight inflammatory reactions of the surrounding mobile mucosa, which necessitated premature removal of two screws. After healing, a new insertion site was chosen. Further treatment was uneventful. Anchorage for orthodontic forces as described offers several advantages. The total treatment time is reduced as the screws can be loaded immediately. The line of action of the orthodontic force coincides with the level of the center of resistance of the molar resulting in a favorable translatory tooth movement. Treatment does not depend on patient cooperation.

Adolescent↗

PubMed2001

Treatment of severe steroid refractory acute graft-versus-host disease with infliximab, a chimeric human/mouse antiTNFalpha antibody.

Acute graft-versus-host disease (aGVHD) is a serious complication of allogeneic peripheral blood stem cell transplantation (PBSCT). Patients with severe aGVHD not responding to treatment with steroids have a poor prognosis. We treated four patients with severe aGVHD refractory to steroids with infliximab, a chimeric human/mouse antiTNFalpha antibody. Patients (CML 2, MM 1, AML 1) developed grade III-IV GVHD at a median of 34 days (range 15-76) after myeloablative PBSCT (two), donor lymphocyte infusion for relapsed CML (one) or non-myeloablative PBSCT (one), respectively. All patients had severe intestinal involvement in addition to skin and/or liver disease and had received treatment with high-dose steroids (four) for a median of 11 days (range 5-17) in addition to CsA (four) and MMF (three). Infliximab (10 mg/kg) was given once a week until clinical improvement. In three of four patients a complete resolution of diarrhea and significant improvement of skin and liver disease were observed. Two patients received one, one patient two and one patient three infliximab infusions. At present two patients are alive >200 days after therapy, one with limited cGVHD. Two patients died, one of progressive malignant disease without GVHD and one of refractory GVHD. Infliximab is apparently an active drug for the treatment of aGVHD.

Acute Disease↗

PubMed2001

Natural transformation competence in Helicobacter pylori is mediated by the basic components of a type IV secretion system.

Helicobacter pylori (Hp), a Gram-negative bacterial pathogen and aetiologic agent of gastroduodenal disease in humans, is naturally competent for genetic transformation. Natural competence in bacteria is usually correlated with the presence of type IV pili or type IV pilin-like proteins, which are absent in Hp. Instead, we recently identified the comB operon in Hp, carrying four genes tentatively designated as orf2, comB1, comB2 and comB3. We show here that all ComB proteins and the 37-amino-acid Orf2 peptide display significant primary sequence and structural homology/identity to the basic components of a type IV secretion apparatus. ComB1, ComB2 and ComB3, now renamed ComB8, ComB9 and ComB10, correspond to the Agrobacterium tumefaciens VirB8, VirB9 and VirB10 proteins respectively. The peptide Orf2 carries a lipoprotein motif and a second cysteine residue homologous to VirB7, and was thus designated ComB7. The putative ATPase ComB4, encoded by the open reading frame hp0017 of strain 26695, corresponds to virB4 of the A. tumefaciens type IV secretion system. A Hp comB4 transposon insertion mutant was totally defective in natural transformation. By complementation of a Hp DeltacomB deletion mutant, we demonstrate that each of the proteins from ComB8 to ComB10 is absolutely essential for the development of natural transformation competence. The putative lipoprotein ComB7 is not essential, but apparently stabilizes the apparatus and modulates the transformation efficiency. Thus, pathogenic type I Hp strains contain two functional independent type IV transport systems, one for protein translocation encoded by the cag pathogenicity island and one for uptake of DNA by natural transformation. The latter system indicates a possible novel mechanism for natural DNA transformation in bacteria.

Amino Acid Sequence↗

PubMed2001

Systematic mutagenesis of the Helicobacter pylori cag pathogenicity island: essential genes for CagA translocation in host cells and induction of interleukin-8.

Helicobacter pylori (Hp) carries a type IV secretion system encoded by the cag pathogenicity island (cag-PAI), which is used to: (i) translocate the bacterial effector protein CagA into different types of eukaryotic cells; and (ii) induce the synthesis and secretion of chemokines, such as interleukin-8 (IL-8). The cag-PAI in Hp 26695 consists of 27 putative genes, six of which were identified as homologues to the basic type IV secretion system represented by the Agrobacterium tumefaciens virB operon. To define the role and contribution of each of the 27 genes, we applied a precise deletion/insertion mutagenesis procedure to knock out each individual gene without causing polar effects on the expression of downstream genes. Seventeen out of 27 genes were found to be absolutely essential for translocation of CagA into host cells and 14 out of 27 for the ability of Hp fully to induce transcription of IL-8. The products of hp0524 (virD4 homologue), hp0526 and hp0540 are absolutely essential for the translocation of CagA, but not for the induction of IL-8. In contrast, the products of hp0520, hp0521, hp0534, hp0535, hp0536 and hp0543 are not necessary for either translocation of CagA or for IL-8 induction. Our data argue against a translocated IL-8-inducing effector protein encoded by the cag-PAI. We isolated a variant of Hp 26695, which spontaneously switched off its capacity for IL-8 induction and translocation of CagA, but retained the complete cag-PAI. We identified a point mutation in gene hp0532, causing a premature translational stop in the corresponding polypeptide chain, providing a putative explanation for the defect in the type IV secretion system of the spontaneous mutant.

Amino Acid Sequence↗

PubMed2001

Interaction of Helicobacter pylori with professional phagocytes: role of the cag pathogenicity island and translocation, phosphorylation and processing of CagA.

Chronic infection of the human gastric mucosa with Helicobacter pylori is a major cause of gastroduodenal pathologies, including peptic ulcerations, mucosa-associated lymphoid tissue (MALT) lymphoma and adenocarcinoma. Helicobacter pylori strains carrying the cag pathogenicity island, which encodes an active type IV protein secretion system (cag+ or type I strains), are preferentially associated with strong gastric inflammation and severe disease. We show here that cag+ H. pylori strains use the type IV secretion system to inject the bacterial protein CagA into various types of professional phagocytes, including human polymorphonuclear leucocytes (PMNs) and the human and murine macrophage cell lines THP-1 and J774A.1 CagA is rapidly tyrosine phosphorylated and proteolytically processed to generate a stable 35-45 kDa C-terminally tyrosine-phosphorylated protein fragment. H. pylori was efficiently ingested by the different types of phagocytic cells. A chromosomal deletion of the complete pathogenicity island had no significant effect on the rate of ingestion. Furthermore, the survival rate of H. pylori in the phagosome was unchanged between the wild type and a deletion mutant lacking the type IV secretion system. Thus, the type IV secretion system seems to be involved neither in active phagocytosis resistance nor in prolonged survival of the bacteria in phagocytic cells.

Animals↗

PubMed2001

Opioid use during the perianesthesia period: nursing implications.

Opioids are used extensively for pain management during the perianesthesia period. These compounds exhibit varying degrees of agonism and antagonism at mu, kappa, and Delta opioid receptors. Stimulation of these receptors cause similar and distinctive actions such as analgesia, euphoria, dysphoria, and respiratory depression. It is imperative that perianesthesia nurses have a clear understanding of opioid receptor site physiology so that maximum analgesic effects are obtained while side effects are minimized.

Analgesics, Opioid↗

PubMed2001

Role of virulence factors, cell components and adhesion in Helicobacter pylori-mediated iNOS induction in murine macrophages.

To investigate the mechanisms involved in Helicobacter pylori-mediated inducible nitric oxide synthase (iNOS) upregulation in mononuclear cells we cocultivated human THP-1 acute monocytic leukemia cells and murine J774A.1 professional macrophages with different H. pylori wild-type strains and mutants. We have shown that H. pylori-mediated iNOS induction in J774A.1 is independent of established virulence factors but dependent on direct interaction between bacteria and cells. In J774A.1, iNOS was equally upregulated by the wild-type strains J99, 26695, P12, and P1 as well as by mutants lacking the cag pathogenicity island, vacA, katA, alpAB genes and the hp0043 gene taking part in lipopolysaccharide biosynthesis when direct cell contact was allowed but not when bacteria and cells were separated by protein-permeable filter membranes. In contrast, iNOS was not induced in THP-1. This indicates that H. pylori-mediated iNOS induction in J774A.1 is independent of important virulence factors whereas cell contact is crucial which suggests a role of adhesion or phagocytosis.

Animals↗

PubMed2001

Outer membrane targeting of passenger proteins by the vacuolating cytotoxin autotransporter of Helicobacter pylori.

Helicobacter pylori produces a number of proteins associated with the outer membrane, including adhesins and the vacuolating cytotoxin. These proteins are supposed to integrate into the outer membrane by beta-barrel structures, characteristic of the family of autotransporter proteins. By using the SOMPES (shuttle vector-based outer membrane protein expression) system for outer membrane protein production, we were able to functionally express in H. pylori the cholera toxin B subunit genetically fused to the C-terminal VacA domain. We demonstrate that the fusion protein is translocated to the H. pylori outer membrane and that the CtxB domain is exposed on the H. pylori surface. Thus, we provide the first experimental evidence that the C-terminal beta-domain of VacA can transport a foreign passenger protein to the H. pylori surface and hence acts as a functional autotransporter.

Amino Acid Sequence↗

PubMed2001

Rapid and accurate determination of genotypic clarithromycin resistance in cultured Helicobacter pylori by fluorescent in situ hybridization.

Phenotypic susceptibility testing for clarithromycin by E-test and disk diffusion of 109 cultured Helicobacter pylori isolates was compared with the genotypic susceptibility determination by fluorescent in situ hybridization (FISH). No discrepancies were found between these three methods. However, FISH has the advantage of providing results after 3 h.

Anti-Bacterial Agents↗

PubMed2001

Specific detection and prevalence of Helicobacter heilmannii-like organisms in the human gastric mucosa by fluorescent in situ hybridization and partial 16S ribosomal DNA sequencing.

Gastric infection with Helicobacter heilmannii (previously known as Gastrospirillum hominis) is invariably linked with the presence of chronic gastritis and the risk of developing low-grade mucosa-associated lymphoid tissue lymphoma in humans. In contrast to Helicobacter pylori, various H. heilmannii species colonize the stomachs of domestic animals, which might be a reservoir for transmission to humans (zoonosis). To identify the number and prevalence of different H. heilmanni types in humans, we analyzed 89 gastric biopsy samples histologically identified as H. heilmannii positive by fluorescence in situ hybridization. Of these gastric specimens, 84 (94.4%) contained a single H. heilmannii type. In five samples, however, two different H. heilmannii types were detected. The most prevalent species in monoinfected samples is H. heilmannii type 1, found in 78.5% (66 of 84) of the specimens, followed by a novel H. heilmannii-like organism (HHLO), HHLO type 4, identified in 9.6% (8 of 84) of tissue sections. H. heilmannii type 2 and a further HHLO type not described before, type 3, were found in 8.3% (7 of 84) and 1.2% (1 of 84) of the monoinfected samples, respectively. Additionally, HHLO type 5 with a 16S ribosomal DNA sequence identical to that of Helicobacter salomonis was found with a prevalence of 2.4% (2 of 89). Thirteen of these biopsy samples were also investigated by a PCR approach developed for this study that allows a Helicobacter-specific amplification of a variable portion of the 16S rRNA gene and subsequent sequencing. In total, five different types of HHLOs could be identified within these samples. We conclude that humans can be infected by at least five different HHLO types, which presumably have their origin in animal species like dogs, cats, and pigs.

Biopsy↗

PubMed2001

Pattern generation for walking and searching movements of a stick insect leg. I. Coordination of motor activity.

During walking, the six legs of a stick insect can be coordinated in different temporal sequences or gaits. Leg coordination in each gait is controlled and stabilized by coordinating mechanisms that affect the action of the segmental neuronal networks for walking pattern generation. At present, the motor program for single walking legs in the absence of movement-related coordinating intersegmental influences from the other legs is not known. This knowledge is a prerequisite for the investigation of the segmental neuronal mechanisms that control the movements of a leg and to study the effects of intersegmental coordinating input. A stick insect single middle leg walking preparation has been established that is able to actively perform walking movements on a treadband. The walking pattern showed a clear division into stance and swing phases and, in the absence of ground contact, the leg performed searching movements. We describe the activity patterns of the leg muscles and motoneurons supplying the coxa-trochanteral joint, the femur-tibial joint, and the tarsal leg joints of the middle leg during both walking and searching movements. Furthermore we describe the temporal coordination between them. During walking movements, the coupling between the leg joints was phase-constant; in contrast during searching movements, the coupling between the leg joints was dependent on cycle period. The motor pattern of the single leg generated during walking exhibits similarities with the motor pattern generated during a tripod gait in an intact animal. The generation of walking movements also drives the activity of thoraco-coxal motoneurons of the deafferented and de-efferented thoraco-coxal leg joint in a phase-locked manner, with protractor motoneurons being active during swing and retractor motoneurons being active during stance. These results show that for the single middle leg, a basic walking motor pattern is generated sharing similarities with the tripod gait and that the influence of the motor pattern generated in the distal leg joints is sufficient for driving the activity of coxal motoneurons so an overall motor pattern resembling forward walking is generated.

Animals↗

PubMed2001

Comparison of double and triple high-dose chemotherapy with autologous blood stem cell transplantation in patients with metastatic breast cancer.

In patients with metastatic breast cancer (MBC), early dose intensification with multiple cycles of peripheral blood stem cell-supported high-dose chemotherapy (HDCT) seems superior to a late dose-intensification strategy. We compared the progression-free survival (PFS) and overall survival (OS) of 20 patients treated with a double (D)-HDCT regimen to 20 patients who received a triple (T)-HDCT, matched by age, estrogen receptor (ER) status, adjuvant chemotherapy, initial disease-free interval, predominant metastatic site, and number of metastatic sites. At a median follow-up of 41.5 months (range, 14-88 months) an intent-to-treat analysis showed no difference in PFS (p = 0.72) and OS (p = 0.93) between the matched patients. For all 76 patients treated within the D- or T-HDCT trial, median PFS and OS was 13 months (range, 2-78 months) and 24.5 months (range, 7-78 months), respectively. In multivariate analysis independent predictors of shorter OS included negative ER (relative risk [RR] = 3.0 [95% confidence interval (CI) 1.5-5.9]; p = 0.002), more than two metastatic sites (RR = 2.4 [95% CI 1.0-5.7]; p = 0.049) and failure to achieve complete remission/no evidence of disease (CR/NED) after HDCT (RR = 4.5 [95% CI 2.0-10.1]; p < 0.0001). These data show that early dose intensification with T-HDCT is not superior to a D-HDCT regimen in patients with MBC. ER-negative tumors, more than two metastatic sites and no CR/NED after HDCT, are associated with inferior outcome.

Adult↗

PubMed2001

Importance of CD44v7 isoforms for homing and seeding of hematopoietic progenitor cells.

The adhesion molecule CD44 consists of many isoforms of which particularly CD44v7 is of major importance in hematopoietic progenitor cell homing. An increase of progenitor cells in the periphery was observed after treating mice with a CD44v7-specific antibody, concomitant with a substantially augmented marrow-repopulating ability (MRA). Because CD44v7 is expressed on a fraction of bone marrow cells (BMC) as well as on long-term bone marrow culture-derived stromal cells, we aimed to differentiate between the functional relevance of CD44v7 on either cell type by transferring CD44v7+/+ BMC into CD44v7-/- mice and vice versa. CD44v7+/+ BMC homed poorly in the bone marrow of CD44v7-/- mice and their MRA was severely impaired. CD44v7-/- BMC, instead, exhibited an improved MRA when transferred into the CD44v7+/+ host, although their MRA remained below that of CD44v7+/+ BMC. Thus, it is predominantly, but not exclusively, expression of CD44v7 on stromal cells which supports progenitor cell homing.

Animals↗