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Biomedical subjects

R Haas

Publications and source records attributed to R Haas.

At least 127 records · Page 7Linked to original sources
PubMed1998

Apolipoprotein A-I induced amyloidosis.

Amyloidosis is characterized by extracellular deposits of protein fibrils with a high content of beta-sheets in secondary structure. The protein forms together with proteoglycans amyloid fibrils causing organ damage and serious morbidity. Intact apolipoprotein A-I (apoA-I) is an important protein in lipid metabolism regulating the synthesis and catabolism of high density lipoproteins (HDL). Usually, apoA-I is not associated with amyloidosis. However, four naturally occurring mutant forms of apoA-I are known so far resulting in amyloidosis. The most important feature of all variants is the very similar formation of N-terminal fragments which were found in the amyloid deposits (residues 1-83 to 1-94). The new insights in the understanding of the association of apoA-I with HDL, its metabolism, and its hypothesized structural findings may explain a common mechanism for the genesis of apoA-I induced amyloidosis. Here we summarized the specific features of all known amyloidogenic variants of apoA-I and speculate about its metabolic pathway, which may have general implications for the metabolism of apoA-I.

Amyloidosis↗
PubMed1998

Gas chromatographic determination of aromatic amines in water samples after solid-phase extraction and derivatization with iodine. I. Derivatization.

A new method for the selective determination of aromatic amines is presented, which is based on the solid-phase extraction at pH 9 and subsequent derivatization of the analytes to the corresponding iodobenzenes. These can selectively and sensitively be determined with gas chromatography and electron-capture detection. Separation of at least 30 compounds in a single chromatographic run in 30 min is possible. With this method, 56 aromatic amines were investigated, and only in six cases no derivatives were obtained. Limits of quantitation were between 0.5 and 8 micrograms 1(-1), but may still be lowered with higher sample volumes or different injection techniques. The application to water samples revealed the suitability for the investigation of ground, leachate and wastewater.

Amines↗
PubMed1998

Oligodeoxyribonucleotide uptake in primary human hematopoietic cells is enhanced by cationic lipids and depends on the hematopoietic cell subset.

The use of antisense oligodeoxyribonucleotides (ODN) is a potential method to switch off gene expression. The poor cellular uptake of ODN in primary cells still is a limiting factor that may contribute to the lack of functional efficacy. Various forms of cationic lipids have been developed for efficient delivery of nucleic acids into different cell types. We examined the two cationic lipids DOTAP and DOSPER to improve uptake of ODN into primary human hematopoietic cells. Using a radiolabeled 23-mer, ODN uptake into blood-derived mononuclear cells could be increased 42- to 93-fold by DOTAP and 440- to 1,025-fold by DOSPER compared with application of ODN alone. DOTAP was also effective for delivery of ODN into leukocytes within whole blood, which may resemble more closely the in vivo conditions. As assessed by fluorescein isothiocyanate-conjugated ODN both cationic lipids enhanced cytoplasmic accumulation of ODN in endosome/lysosome-like structures with a partial shift of fluorescence to the whole cytoplasm and the nucleus following an incubation of 24 hours. ODN uptake by cationic lipids into different hematopoietic cell subsets was examined by dual-color immunofluorescence analysis with subset-specific monoclonal antibodies. We found a cell type-dependent delivery of ODN with greatest uptake in monocytes and smallest uptake in T cells. CD34+ cells, B cells, and granulocytes took up ODN at an intermediate level. Uptake of ODN into isolated CD34+ cells could be increased 100- to 240-fold using cationic lipids compared with application of ODN alone. Stimulation of CD34+ cells by interleukin-3 (IL-3), IL-6, and stem cell factor did not significantly improve cationic lipid-mediated ODN delivery. Sequence-specific antisense effects in clonogenic assays could be shown by transfection of bcr-abl oncogene-directed antisense ODN into primary cells of patients with chronic myelogenous leukemia using this established protocol. In conclusion, cationic lipids may be useful tools for delivery of antisense ODN into primary hematopoietic cells. These studies provide a basis for clinical protocols in the treatment of hematopoietic cells in patients with hematologic malignancies and viral diseases by antisense ODN.

Antibodies, Monoclonal↗
PubMed1998

Decreased numbers of circulating B cells in myeloma patients with reduction after conventional chemotherapy.

Reports of high numbers of circulating monotypic B cells in patients with multiple myeloma (MM) have recently been published. These cells, which were identified by their expression of CD19, were reported to be resistant to conventional chemotherapy and to represent the source of relapse. We examined blood samples from 48 patients before and 53 patients after glucocorticoid containing chemotherapy by dual color flow cytometry. The absolute count of CD19+B cells in patients before treatment (212.6+/-24.8 x 10(6)/l) was decreased compared to normal controls (P = .038). In the post-treatment group, circulating B cells were highly significantly lower than in untreated patients (45.23+/-6.69 x 10(6)/l. P < .001). This reduction was also seen in 26 patients, that were followed during chemotherapy. The cytoplasmic kappa/lambda ratio was within normal range before and after treatment with no difference according to the light chain isotype of the paraprotein. We conclude that circulating B cells are not increased in patients with MM, that the majority of these cells are polyclonal, and that conventional chemotherapy effectively reduces circulating B cells without leading to dominance of resistant monotypic cells.

ADP-ribosyl Cyclase↗
PubMed1998

Genetic monitoring of malathion-exposed agricultural workers.

The aerial application of malathion over large urban populations in Southern California during the early 1990s raised concerns about adverse health effects, including the potential to cause genetic damage. Workers in the Mediterranean fruit fly eradication program, which involved application of malathion as ground treatment, were studied to examine micronucleus formation and mutation frequencies assessed by the glycophorin A (GPA) assay. In the 1992 pilot project the mean micronuclei level appeared higher in lymphocytes of exposed workers (n = 13) compared to controls (n = 4) (20.1 +/- 7.1 vs 14.3 +/- 7.2 respectively, P = 0.09). During the 1993 season, neither of the cohorts examined showed a higher level of micronuclei in workers exposed to malathion compared to unexposed, nor did the pooled total (n = 53; means = 17.8 +/- 7.2 vs 18.5 +/- 6.3, respectively), even after adjustment by multiple regression. The GPA variant frequency was not associated with malathion exposure in any of the cohorts. These results suggest that any potential risk of genotoxic damage from exposure to malathion is relatively low, but other assays may be more sensitive, and the sample size was small.

Adult↗
PubMed1998

Delineation of cell cycle state and correlation to adhesion molecule expression of human CD34+ cells from steady-state bone marrow and peripheral blood mobilized following G-CSF-supported chemotherapy.

Treatment with a combination of chemotherapy and G-CSF leads to the release of hematopoietic stem cells from the bone marrow (BM) to the peripheral blood (PB), where they can be harvested for transplantation. Premobilization BM CD34+ cells were reported to proliferate actively, while virtually none of the mobilized PB CD34+ cells were in the S/G2M phase. We were interested in elucidating the cell cycle state further and in investigating the role of adhesion molecule expression on marrow-adherent and circulating CD34+ cells during different phases of the cell cycle. Consecutive premobilization BM and leukapheresis product (LP) samples were obtained from 14 patients following G-CSF-supported chemotherapy. Steady-state BM and LP CD34+ selected cells were triple-stained for CD34, for DNA using the intercalating dye 7-aminoactinomycin D, and for Ki-67, cyclins, or adhesion antigens. Ki-67 is expressed in all phases of the cell cycle except G0 and was found in 69.14%+/-3.46% (mean +/- standard error [SE]) of BM CD34+ cells and 62.78%+/-3.37% of LP CD34+ cells, while in BM significantly more CD34+/Ki-67+ cells were in the S/G2M phase of the cell cycle than in LP (8.6%+/-0.9% versus 1.8%+/-0.3%, respectively, p = 0.0001). Therefore, most circulating mobilized CD34+ cells are in the G1 phase, similar to their steady-state BM counterparts. Cyclin A became detectable in the 2n DNA peak. As expected, a higher proportion of CD34+/cyclin A+/S/G2M cells was found in BM than in LP (p < 0.05). Antigen density of the cyclins D3 and D2 tended to be higher on LP than on BM CD34+ cells, while D1 was found at low levels in similar density. The adhesion antigens CD18, CD49b, CD49d, CD49e, CD58, and CD62L were expressed in a significantly higher proportion of S/G2M-phase than in G0/G1-phase CD34+ cells. The strongest association to the proliferative status was observed for CD49d, which was coexpressed by 85.9% +/-2.6% (BM) or 90.8%+/-2.5% (LP) of CD34+/S/G2M cells, whereas a distinct CD34+/CD49d-/S/G2M population could not be detected. The average coexpression of the other antigens was 57% (CD49e, CD18) or lower. Our results demonstrate that the majority of PB CD34+ cells mobilized following G-CSF-supported chemotherapy and steady-state BM CD34+ cells are in the late G1 phase of the cell cycle and show a correlation between the expression of adhesion receptors and cell cycle status of CD34+ cells in both BM and LP.

Adult↗
PubMed1998

Protection of hematopoietic stem cells from chemotherapy-induced toxicity by multidrug-resistance 1 gene transfer.

An increased chemotherapeutic dose intensity is believed to translate into higher survival rates among cancer patients. Pancytopenia is the dose-limiting toxic result of most anticancer agents. Overexpression of the human multidrug resistance 1 (MDR1) gene in transgenic animals resulted in complete myeloprotection against high doses of cytostatic drugs. Stem cell research, vector development, and experimental pharmacology are uniting their efforts in an attempt to achieve a similar effect in human hematopoietic stem cells. This article gives an overview of the crucial steps involved, from retroviral vector design and optimization of viral titers to vector uptake, gene integration, and expression. The authors' own results are presented with special regard in vitro and in vivo assays for the detection of hematopoietic stem cell transduction.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1998

Peripheral blood progenitor cell transplantation in multiple myeloma following high-dose melphalan-based therapy.

The objective of our study was to evaluate the efficacy and toxicity of a high-dose melphalan-based therapy with or without total body irradiation (TBI) followed by peripheral blood progenitor cell (PBPC) transplantation in patients with multiple myeloma. Between June 1992 and June 1996, 104 patients (71 male, 33 female) with a median age of 51 years (range 30-65 years) underwent transplantation at our center. PBPC were mobilized using high-dose chemotherapy followed by treatment with G-CSF. Fifty patients were treated with TBI+melphalan 140 mg/m2 while 54 patients received melphalan 200 mg/m2. Following PBPC autografting, the median time to attainment of platelets > or = 20 x 10(9)/l and neutrophils > or = 0.5 x 10(9)/l was 11 and 14 days, with no difference between the treatment groups. In the TBI group significantly longer periods of total parenteral nutrition were required due to the occurrence of severe mucositis. Two patients from the TBI group died of transplantation-related complications. Following high-dose treatment, remission state improved in 43 out of 102 patients. No statistically significant advantage in reaching complete or partial remission was observed with TBI+high-dose melphalan compared to the treatment with high-dose melphalan alone. The optimal high-dose treatment, with particular reference to the inclusion or omission of TBI, should be prospectively investigated.

Adult↗
PubMed1998

The influence of the spring activator on the mobility of the lower jaw in traumatically injured patients.

For functional rehabilitation and improvement of mandibular mobility, 14 patients with dislocated collum or collum fracture dislocations were treated with a spring activator after surgical-conservative treatment. With an interincisal distance of < 12 mm, therapy was started with a loop spring. The average age of the patients was 26.6 years. Eight patients showed additional traumatic injuries, 2 patients were seriously polytraumatically injured. The clinical investigations referring to the maximum mouth opening and maximal interincisal distance resulted in a good to very good functional rehabilitation in all cases. The average maximal interincisal distance of 31.7 mm at the beginning of the spring activator therapy could be increased to 47.3 mm. The largest increase of the maximal interincisal distance was observed after 4 weeks of therapy. The type of reaction, however, differed interindividually. Three patients showed a spontaneous improvement of the interincisal distance within the first 2 to 3 weeks of removal of intermaxillary fixation, whereas 7 patients showed no improvement or only slightly improved values until insertion of the spring activator. An enlargement of the interincisal distance could be achieved in almost every patient within a relatively short period of time despite a drastically reduced mouth opening. Consequently, because of its mode of action in the form of a neuromuscular influence, the spring activator is especially suitable for the functional rehabilitation of patients with fractures of the condylar process.

Activator Appliances↗
PubMed1998

The human immunodeficiency virus (HIV)-type 1 coreceptor CXCR-4 (fusin) is preferentially expressed on the more immature CD34+ hematopoietic stem cells.

In synergy with the CD4 antigen, the chemokine receptor CXCR-4 functions as a coreceptor for T-cell-tropic HIV-1 strains. Using two- and three-color immunofluorescence analysis, we examined the expression of CXCR-4 on CD34+ cells in 21 samples obtained from leukapheresis (LP) products of cancer patients who underwent G-CSF-supported cytotoxic chemotherapy. In addition, eight samples from bone marrow (BM) were obtained. CXCR-4 was expressed on the surface of CD34+ cells from samples of both hematopoietic sources. The mean proportion of CD34+/CXCR-4+ cells from LP products was 1.7-fold greater in comparison with those from bone marrow (65.9+/-4.1% vs. 37.5+/-8.6% [+/- SEM], p < 0.05). For an intraindividual comparison, LP products and bone marrow from six patients were obtained on the same day, confirming the significantly greater proportion of CD34+ cells coexpressing CXCR-4 cells in LP products. In order to examine whether the CXCR-4 expression was related to the stage of maturation and differentiation of CD34+ cells, six samples from LP products and four samples from bone marrow were assessed using three-color immunofluorescence analysis. We found that the subset of CD34+/CD38low and CD34+/HLA-DRlow cells representing a population of more immature progenitor cells were brightly positive for CXCR-4, while there was a decrease in the level of CXCR-4 expression in the population of CD34+/HLA-DRbright and CD34+/CD38bright cells. Based on the assessment of ten LP products, we found that the mean proportion of CD34+ cells coexpressing CD4 and CXCR-4 was 6.2+/-2.3% [+/- SEM], suggesting that a small population of CD34+ cells are, in principle, susceptible for an infection with T-cell-tropic HIV-1 strains. In conclusion, our data suggest that CXCR-4 is present on the surface of hematopoietic progenitor cells--particularly more primitive CD34+ cells. CXCR-4 could play a role in the homing of CD34+ cells to stromal elements of the bone marrow via its natural ligand stromal-derived factor-1 (SDF-1).

Antigens, CD↗
PubMed1998

A case of mu heavy-chain disease associated with hyperglobulinemia, anemia, and a positive Coombs test.

We report here for the first time a patient with mu heavy-chain disease (HCD), hyperimmunoglobulinemia, and a positive direct antiglobulin test (DAT, Coombs test). The heavy-chain diseases involve the proliferation of lymphoplasma cells of B cell origin and are characterized by the production of incomplete heavy chains devoid of light chains. The association of mu heavy-chain disease with either hyperglobulinemia or a positive DAT has not been reported in the literature to date. In this patient, immunofixation of serum proteins with monospecific antisera to alpha-, gamma-, mu,- or delta-chains and to kappa- and lambda-chains revealed a precipitation band with antibody to IgM, but not with kappa and lambda light-chain antibodies, indicating mu heavy-chain disease. Hyperglobulinemia was present, which is very uncommon for HCD. A DAT of the patient's red blood cells (RBC) was found to be strongly positive for anti-IgG but negative for anti-IgM, -IgA, -C3c, and -C3d. However, when the eluate from the patient's red blood cells was investigated with nephelometry, it was found to contain antigens reactive with anti-y as well with anti-mu-antiserum. When a DAT was performed with a randomly chosen test cell incubated with the eluate, the antibody-containing eluate was shown to react with anti-IgG as well as with anti-IgM-antiserum. In summary, the eluate from the patient's RBCs contained IgG and an immunoglobulin structure reactive with anti-IgM in an RBC agglutination assay as well as with anti-mu antiserum in a nephelometric investigation. Whether this IgM on the patient's erythrocytes is penta- or oligomeric, complete IgM, or the heavy chain cannot be concluded from these observations.

Aged↗
PubMed1998

Hemolytic properties and riboflavin synthesis of Helicobacter pylori: cloning and functional characterization of the ribA gene encoding GTP-cyclohydrolase II that confers hemolytic activity to Escherichia coli.

Various strains of Helicobacter pylori were able to lyse erythrocytes from sheep, horse, and human when grown on blood agar. The hemolysis did not depend on the production of the vacuolating cytotoxin VacA as demonstrated by the hemolytic behavior of an isogenic vacA-negative mutant strain. The hemolytic activity could be detected in cell-free supernatants and was not regulated by iron. To isolate genes coding for proteins involved in the destruction of erythrocytes, a plasmid-based DNA library was screened for expression of lytic activity on blood agar. This approach revealed that the H. pylori ribA gene confers hemolytic properties to Escherichia coli. The ribA gene encodes the enzyme GTP-cyclohydrolase II [EC 3.5.4.25] that catalyzes the initial step in the synthesis of riboflavin. The predicted amino acid sequence of the H. pylori RibA protein showed a high degree of similarity to equivalent enzymes from microorganisms and from plants. The single gene on a plasmid restored riboflavin synthesis in a ribA mutant of E. coli and induced hemolytic activity. Furthermore, ribA overexpression was associated with the production of a fluorescent yellow molecule that was not identical with riboflavin. Hemolysis was also seen for the ribA gene from E. coli, indicating that this feature was not specific for the H. pylori gene. The presence of ribA in various H. pylori strains was confirmed by Southern blot hybridization and by polymerase chain reaction with specific primers. This analysis revealed that microdiversity exists within the DNA region upstream from ribA, which was further confirmed by nucleotide sequence analysis.

Amino Acid Sequence↗
PubMed1998

Tandem and triple high-dose chemotherapy with autologous stem cell rescue in metastatic breast cancer.

The purpose of this phase II study was to evaluate the therapeutic efficacy and toxicity of a tandem or triple high-dose chemotherapy (HDC) with autologous peripheral blood stem cell transplantation (PBSCT) in patients with metastatic breast cancer (MBC) as first line chemotherapy. Conventional chemotherapy consisted of two cycles of epirubicin 120 mg/m2 and ifosfamide 7500 mg/m2 in the case of tandem HDC and one cycle of paclitaxel 135 mg/m2, epirubicin 90 mg/m2 and ifosfamide 6000 mg/m2 in the case of triple HDC. Tandem HDC was composed of two cycles of epirubicin 180 mg/m2, ifosfamide 12000 mg/m2 and carboplatin 900 mg/m2. In the case of triple HDC, paclitaxel 180 mg/m2, etoposide 1500 mg/m2 and thiotepa 600 mg/m2 was added as the third cycle. Patients with tandem HDC (n = 20) were evaluable for both survival and toxicity, and patients with triple HDC (n = 21) only for toxicity because of short-term follow-up. Both tandem and triple HDC were well tolerated and could be safely administered. Non-hematological WHO grade 3 or 4 toxicities were mucositis (8), temporary renal insufficiency (1), myocardial infarction (1), and neuropathy (1). No toxic death occurred. The Kaplan-Meier estimates for 44-months without progression and the overall survival were 12% and 38% respectively. The median survival was 22 months (95% CI: 7.4-51.7 months) and the median progression-free interval 14 months (95% CI: 5.1-43.7 months). In a population with an unfavorable prognosis, tandem HDC showed similar efficacy as to that described in other phase II studies. Triple HDC seems not to improve patient outcome compared to tandem HDC, but a long-term follow up is required.

Adult↗
PubMed1998

A stable shuttle vector system for efficient genetic complementation of Helicobacter pylori strains by transformation and conjugation.

A versatile plasmid shuttle vector system was constructed, which is useful for genetic complementation of Helicobacter pylori strains or mutants with cloned genes of homologous or heterologous origin. The individual plasmid vectors consist of the minimal essential genetic elements, including an origin of replication for Escherichia coli, a H. pylori-specific replicon originally identified on a small cryptic H. pylori plasmid, an oriT sequence and a multiple cloning site. Shuttle plasmid pHel2 carries a chloramphenicol resistance cassette (catGC) and pHel3 contains a kanamycin resistance gene (aphA-3) as the selectable marker; both are functional in E. coli and H. pylori. The shuttle plasmids were introduced into the H. pylori strain P1 by natural transformation. A efficiency of 7.0 x 10(-7) and 4.7 x 10(-7) transformants per viable recipient was achieved with pHel2 and pHel3, respectively, and both vectors showed stable, autonomous replication in H. pylori. An approximately 100-fold higher H. pylori transformation rate was obtained when the shuttle vectors for transformation were isolated from the homologous H. pylori strain, rather than E. coli, indicating that DNA restriction and modification mechanisms play a crucial role in plasmid transformation. Interestingly, both shuttle vectors could also be mobilized efficiently from E. coli into different H. pylori recipients, with pHel2 showing an efficiency of 2.0 x 10(-5) transconjugants per viable H. pylori P1 recipient. Thus, DNA restriction seems to be strongly reduced or absent during conjugal transfer. The functional complementation of a recA-deficient H. pylori mutant by the cloned H. pylori recA+ gene, and the expression of the heterologous green fluorescent protein (GFP) in H. pylori demonstrate the general usefulness of this system, which will significantly facilitate the molecular analysis of H. pylori virulence factors in the future.

Colistin↗
PubMed1998

A minimally invasive second-stage procedure for single-tooth implants.

The natural look of dental restorations has become a universally claimed treatment objective, especially when single-tooth gaps are restored with implants. A harmonious gingival margin is crucial to achieve this goal. This article presents a new procedure for exposure of single-tooth implants that yields a favorable esthetic result in the visible maxillary regions because of the simple type of incision used. The procedure consists of two incisions: the first incision makes it possible to find out the implant position and the second incision shapes the mucous membrane according to local supply. The second incision also prevents the soft tissue from tearing after careful stretching and subsequent pressing of the supraimplant mucosa. There is minimal soft tissue traumatization, and as a result, healing time can be reduced to 1 week and an appealing esthetic result can be reached.

Dental Implantation, Endosseous↗