Search PubMed⌕ Search

Biomedical subjects

M Wilhelm

Publications and source records attributed to M Wilhelm.

At least 109 records · Page 6Linked to original sources
PubMed1998

Some neurohistochemical properties of nerve elements in myenteric plexus of rabbit ileum: similarities and dissimilarities to the rodent pattern.

Enteric neurons have distinct neurochemical codings in each species. The basal tone of the gastrointestinal tract of the rabbit is low and produces neurally evoked pendular movements. Therefore, it might have an innervation pattern different from that of other laboratory animals. We have characterised myenteric neuron populations in rabbit ileum with neurochemical markers that are known to be associated with distinct cell types and/or fibre systems in the myenteric plexus. The density of nerve cells estimated with the NADH-diaphorase technique was about 2500 cells/cm2 and most, if not all, neurons contained microtubule-associated protein 2. NADPH-diaphorase-positive cells were numerous. One cell type was large and emitted long straight processes, whereas small cells bore thin filamentous dendrites. Neurons immunoreactive for 28-kDa calcium-binding protein were rare. Over 70% of them had very strongly labelled lamellar dendrites. Their axons were beaded and formed pericellular baskets around unstained somata. We found very few small tyrosine-hydroxylase-positive cells. The fibre network in the plexus was very strong; the axons formed many pericellular baskets. In double labelling studies, no co-localisation was revealed between the 28-kDa calcium-binding protein and NADPH-diaphorase. Some fibres containing 28-kDa calcium-binding protein formed only a few contacts on somata of NADPH-diaphorase-positive cells. None of the NADPH-diaphorase-labelled cells were found to be stained for tyrosine hydroxylase. Tyrosine-hydroxylase-positive fibres rarely made pericellular baskets on the surface of NADPH-diaphorase-positive somata. Strongly immunolabelled pericellular baskets were never observed around NADPH-diaphorase-positive cell somata. The results suggest that myenteric neurons in rabbit comprise distinct and characteristic neurochemical properties that are different from the rodent pattern. Therefore, the explanation of the motility pattern of rabbit intestine can be approached on a chemical neuroanatomical basis.

Animals↗
PubMed1998

Supernatants from quartz dust treated human macrophages stimulate cell proliferation of different human lung cells as well as collagen-synthesis of human diploid lung fibroblasts in vitro.

Silicosis is a chronic lung disease, which is caused by inhalation of silica-containing dusts, leading to pulmonary fibrosis. Alveolar macrophages play a key-role in defence against these particles entering the lung. As a result of phagocytosis, the macrophages release mediators, which are involved in various processes of inflammation and immunological defence mechanisms. We established an in-vitro test system composed of human macrophages, human pneumocyte type II cells (line A-549), human diploid lung fibroblasts (line Wi38) and human tracheobronchial epithelial cells (line BEAS-2B). With this model, we were able to study the influence of various cytokines, produced by the macrophages, on cell proliferation and collagen synthesis (only fibroblasts) of the cells in our test-system. In this report, we will summarize data obtained from our in-vitro test system on two cytokines, which are thought to be important in pathogenesis of lung fibrosis: insulin-like growth factor-1 (IGF-1) and transforming growth factor-beta (TGF-beta).

Cell Division↗
PubMed1998

Lack of interleukin 6 (IL-6) and transforming growth factor alpha (TGF-alpha) expression in chromophobe renal cell carcinomas.

We demonstrate the constitutive expression of interleukin 6 (IL-6), IL-8, granulocyte-macrophage colony-stimulating factor (GM-CSF), epidermal growth factor (EGF), transforming growth factor alpha (TGF-alpha) and epidermal growth factor receptor (EGFR) in normal kidney cells, and in the majority of renal oncocytomas, papillary and non-papillary renal cell carcinomas (RCCs) by reverse transcriptase polymerase chain reaction (RT-PCR) technique. No expression of IL-6 and TGF-alpha and variable expression of GM-CSF, IL-8, EGF and EGFR was seen in chromophobe RCCs. The lack of expression of IL-6 and TGF-alpha might be correlated with the growth pattern, poor vascularity and low malignancy of chromophobe RCCs.

Carcinoma, Papillary↗
PubMed1998

Effect of interferon-alpha therapy on bone marrow fibrosis in chronic myelogenous leukemia.

The aim of this study was to investigate the influence of interferon-alpha (IFN-alpha) on bone marrow fibrosis associated with chronic myelogenous leukemia (CML). Eighty-two bone marrow biopsies from 41 patients in chronic phase CML were stained with Snook's reticulin stain for argyrophilic fibers. Grading of reticulin fibrosis (scale of 1 to 4) was according to the quantity and pattern of distribution of reticulin. The interval between biopsies was a median of 25 months (range 12 to 40 months). Patients had been treated with IFN-alpha for at least 12 months, were still on IFN-alpha therapy during the study, and had achieved at least a complete hematological response. Before the start of IFN-alpha therapy, reticulin fibrosis was grade 1-2 in 23 patients (56%) and grade 3-4 in 18 (44%). During IFN-alpha therapy, reticulin fibrosis in bone marrow did not worsen or was reduced in 33 patients (80%) and increased by one grade in eight patients (20%). Only five patients (12%) with limited fibrosis (grade 1-2) before start of IFN-alpha therapy showed an increase towards significant fibrosis (grade 3-4), while eight of the 18 patients (44%) with grade 3-4 fibrosis achieved a decrease of fiber content in bone marrow. In summary, IFN-alpha was not associated with an enhancing effect on myelofibrosis in patients with CML and may have prevented increasing fibrosis in patients who respond to therapy.

Adult↗
PubMed1998

[Combined use of ECK-triggered 2D-phase contrast MR angiography and 2D-time-of-flight MR angiography for planning and follow up before and after vascular intervention of pelvic and leg arteries].

PURPOSE: To develop a strategy for the complete work-up of vessel lumen and vessel wall for planning and follow-up of radiological interventions of lower extremity arteries. METHODS: A total of 36 patients (21 pre-, 8 post- and 7 pre- and postinterventional) were studied. MRA studies were performed using an ECG-triggered phase contrast technique for the demonstration of intraluminal flow and an axial high resolution time-of-flight technique to assess the vascular wall. All MRA studies were analysed by intraindividual DSA comparison for the assessment of flow and wall structures. RESULTS: Combined MRA techniques provided a good correlation with DSA for the assessment of vascular flow. The kappa test revealed a value of greater than 0.61 for most on the vessel segments proving a good correlation of both methods. Orthogonal high-resolution TOF-MRA provided additional information for the assessment postinterventional wall haematomas and hard plaques. CONCLUSION: Combination of PCA to study flow and axial TOF to study wall pathology improves the usefulness of peripheral MRA.

Adult↗
PubMed1998

Comparison of free-living amoebae in hot water systems of hospitals with isolates from moist sanitary areas by identifying genera and determining temperature tolerance.

Legionella-contaminated hot water systems and moist sanitary areas in six hospitals were sampled for amoebae by following a standardized collection protocol. Genus identifications and temperature tolerance determinations were made. Amoebae identified as Hartmannella vermiformis (65%), Echinamoebae spp. (15%), Saccamoebae spp. (12%), and Vahlkampfia spp. (9%) were detected in 29 of 56 (52%) hot water samples. Twenty-three of 49 (47%) swabs obtained from moist areas were amoeba positive. The following genera were identified: Acanthamoeba (22%), Naegleria (22%), Vahlkampfia (20%), Hartmannella (15%), and Vanella (7%). The temperature tolerance of amoebae from hot water systems was strikingly different from that of amoebae from moist areas. At 44 degrees C on agar, 59% of amoebic isolates sampled from hot water systems showed growth. The corresponding value for isolates from moist areas was only 17%. Six Acanthamoeba isolates from the moist areas were considered potential pathogens. Four Hartmannella and two Saccamoeba isolates from hot water could be cultured at 53 degrees C.

Acanthamoeba↗
PubMed1998

Interactions between Ty1 retrotransposon RNA and the T and D regions of the tRNA(iMet) primer are required for initiation of reverse transcription in vivo.

Reverse transcription of the Saccharomyces cerevisiae Ty1 retrotransposon is primed by tRNA(iMet) base paired to the primer binding site (PBS) near the 5' end of Ty1 genomic RNA. The 10-nucleotide PBS is complementary to the last 10 nucleotides of the acceptor stem of tRNA(iMet). A structural probing study of the interactions between the Ty1 RNA template and the tRNA(iMet) primer showed that besides interactions between the PBS and the 3' end of tRNA(iMet), three short regions of Ty1 RNA, named boxes 0, 1, and 2.1, interact with the T and D stems and loops of tRNA(iMet). To determine if these sequences are important for the reverse transcription pathway of the Ty1 retrotransposon, mutant Ty1 elements and tRNA(iMet) were tested for the ability to support transposition. We show that the Ty1 boxes and the complementary sequences in the T and D stems and loops of tRNA(iMet) contain bases that are critical for Ty1 retrotransposition. Disruption of 1 or 2 bp between tRNA(iMet) and box 0, 1, or 2.1 dramatically decreases the level of transposition. Compensatory mutations which restore base pairing between the primer and the template restore transposition. Analysis of the reverse transcription intermediates generated inside Ty1 virus-like particles indicates that initiation of minus-strand strong-stop DNA synthesis is affected by mutations disrupting complementarity between Ty1 RNA and primer tRNA(iMet).

Base Sequence↗
PubMed1998

The genetics of renal tumors in end-stage renal failure differs from those occurring in the general population.

The genetics of renal cell tumors (RCT), which occur at a high frequency in patients with end-stage renal failure (ESRF), is not yet known. Using a fluorescence microsatellite assay and comparative genomic hybridization, 18 renal tumors obtained from nine patients with ESRF were analyzed for genetic alterations, which are known to be characteristic of common nonpapillary and papillary RCT in the general population. Deletion of chromosome 3p was detected in six nonpapillary tumors, whereas trisomies of 7 and 17 or 3, 8, and 16 were seen in four of 18 tumors. No alterations were found in four tumors, and another four tumors had unspecific changes. The fragile histidine triad (FHIT) gene is localized at the most common fragile site at chromosome 3p14.2. The FHIT and the p53 tumor suppressor gene are targets of different environmental agents. Because both toxic effect and genomic instability are implicated in the development of renal cysts in ESRF, the alteration of both genes in tumor cells was analyzed. No abnormal expression of the FHIT gene or mutation of the p53 gene were found. This study suggests that the genetics and also the morphology of some of the ESRF RCT differ from those known for RCT in the general population.

Acid Anhydride Hydrolases↗
PubMed1998

DIZE (dexamethasone, idarubicin, and continuous infusion of ifosfamide and etoposide): an effective and well-tolerated new regimen for patients with relapsed lymphoma.

We performed a phase II study of dexamethasone, ifosfamide, idarubicin and etoposide (DIZE) in patients with relapsed or refractory Hodgkin's (HL) and non-Hodgkin's lymphoma (NHL). The regimen consisted of dexamethasone (20 mg i.v. days 1-4), idarubicin (8 mg/m2 i.v. days 1+2), continuous infusion (c.i.) of ifosfamide (1,000 mg/m2 days 1-4), and c.i. etoposide (60 mg/m2 days 1-4). G-CSF (5 microg/kg) was used to support neutrophil recovery from day 5. In older patients (> 60 years) the dosage of idarubicin and ifosfamide was reduced to 75% in the initial cycle. Fourty six patients (pts) were treated with a total of 131 cycles. Sixteen pts were primary resistant and 30 were relapsed. Median age was 54.3 years (range 22-75). The median number of different prior chemotherapies was 1.7 (range 1 to 5). 31/46 (67.4%) pts had advanced disease (stage III or IV); 19/46 had B symptoms. Of 43 evaluable pts the response rate was 58.1% including 11 complete remissions (CR) and 14 partial remissions (PR). Mean duration of response was 8 months (1-30+). DIZE was more effective in relapsed than in refractory high-grade NHL (74 % vs 16.6%; p < 0.001). Of four heavily pretreated pts with HL, one obtained CR and two PR (response rate 75%). Myelosuppression was generally moderate with a mean duration of leukocytopenia < 1,000/microl of 2.5 days (range 0-18) and of thrombocytopenia < 25,000/microl 1.5 days (range 0-17). One patient died of uncontrollable infection in treatment related neutropenia. No other serious toxicities apart from alopecia were observed. We conclude that DIZE is safe and effective in heavily pretreated pts with relapsed lymphoma. The continuous infusion of cytostatic drugs such as that used in the new DIZE protocol might reduce hematotoxicity.

Adult↗
PubMed1998

NADPH-diaphorase positive myenteric neurons in the ileum of guinea-pig, rat, rabbit and cat: a comparative study.

The nitrergic system of the ileal myenteric plexus of four mammalian species was studied by means of NADPH diaphorase histochemistry which in aldehyde-fixed tissue stains only those cells that contain the constitutive, calcium-dependent nitrogen monoxide synthase isoenzyme. Since previous studies assumed minor species-specific anatomical variations, we sought similarities and differences in the nitrergic innervation pattern of the ileal musculature. In rat and guinea-pig, the ratio of nitrergic cells slightly exceeds 20%, in rabbit it is close to this number (16%), and it is lowest in cat (about 10%). The nitrergic neurons target the circular muscle layer in all investigated species where they participate in inhibitory motoric transmission. Apart from this, some elements of the sensory innervation of the circular musculature may derive from nitrergic neurons in rat and rabbit. The tertiary plexus (longitudinal muscles) is strongly supplied by NADPH diaphorase positive fibres in rat, moderately in guinea-pig and cat and not at all in rabbit. The rest of the nitrergic neurons may serve as inhibitory interneurons and control other (probably excitatory motor) neurons in the myenteric plexus. We conclude that the diverse physiological and pharmacological properties of the nitrergic system described in the small intestine in different species can be connected with the anatomical heterogeneity of its elements.

Animals↗
PubMed1997

Bimodal distribution of angiographic measures of restenosis six months after coronary stent placement.

BACKGROUND: Restenosis has been perceived as the tail end of a normal distribution of the response of the vessel to the intervention. However, recent studies have described a bimodal distribution for de novo lesions after percutaneous transluminal coronary angioplasty. This finding suggests that some lesions may be more susceptible for restenosis. Whether this holds true for a wider spectrum of lesions undergoing stent placement is not yet known. The present study analyzes the frequency distribution of angiographic indexes of restenosis 6 months after coronary stent implantation. METHODS AND RESULTS: Quantitative angiographic evaluation was performed in 1084 lesions of 1084 patients before, immediately after, and 6 months after successful Palmaz-Schatz stent placement; this represented 80.4% of patients eligible for follow-up angiography. Principal end points of the analysis were angiographic indexes of restenosis at 6 months. Twenty-two lesions that became totally occluded at follow-up were excluded from most parts of the analysis. Diameter stenosis, minimal luminal diameter (MLD), and lumen loss at 6 months did not follow a normal pattern; the bimodal pattern was demonstrated through deconvolution that yielded two separate normal components delineating two lesion populations, which developed distinctively different degrees of lumen renarrowing. The first and larger subgroup of lesions, which was less prone to restenosis, was centered around a mean value of 27% for diameter stenosis and 2.19 mm for MLD, whereas the second subgroup, with a greater tendency for restenosis, was situated around a mean value of 68% for diameter stenosis and 0.76 mm for MLD. The intersection point between the two theoretical normal distribution components was 53.5% for diameter stenosis and 1.09 mm for MLD at follow-up. CONCLUSIONS: Frequency-distribution curves of angiographic indexes of restenosis after coronary stent placement have a bimodal pattern, suggesting the existence of two distinct populations with different propensity to restenosis. These findings may encourage future efforts for the timely identification of the subset with a higher risk as the target of specific antirestenotic strategies.

Aged↗
PubMed1997

Detailed microsatellite analysis of chromosome 3p region in non-papillary renal cell carcinomas.

Multiple hemi- and homozygous interstitial deletions at chromosome 3p have been found in different types of cancer, including non-papillary renal cell carcinoma (RCC). To determine the frequency and size of deletions, we have analyzed paired normal and tumor DNA obtained from short-term cultures of 104 non-papillary RCCs with 29 microsatellite markers covering the entire chromosome 3p region. Deletion mapping provided evidence for terminal deletion, with the most distal breakpoint between loci D3S1606 and D3S3666 in 94 cases, whereas constitutional heterozygosity was retained at all loci in 4 RCCs. In 6 cases, interstitial deletions were detected. Deletion mapping detected the smallest overlapping region between loci D3S3666 and D3S1560, which corresponds to an approx. 55 cM genetic distance.

Carcinoma, Renal Cell↗
PubMed1997

Sequence comparison of the Ty1 and Ty2 elements of the yeast genome supports the structural model of the tRNAiMet-Ty1 RNA reverse transcription initiation complex.

In the reverse transcription initiation complex of the yeast Ty1 retrotransposon, interaction between the template RNA and primer tRNAiMet is not limited to base pairing of the primer binding site (PBS) with ten nucleotides at the 3' end of tRNAiMet, but three regions named boxes O, 1 and 2.1 interact with the T and D stems and loops of tRNAiMet. Sequence comparison of 33 Ty1 elements and 13 closely related Ty2 elements found in the yeast genome shows that the nucleotide sequence of all elements is highly conserved in the region spanning the PBS and the three boxes. Since the domain of the template RNA encodes a portion of protein TyA, we have calculated its amino acid profile and its nucleotide profile to evaluate the role played by nucleotide sequence conservation in the selection for TyA function and in the maintenance of base pairing interactions for the priming function of Ty1 RNA. Our results show that the nucleotide sequence conservation of Ty1 RNA is constrained not only by selection for Ty1 function but also by maintenance of a given nucleotide sequence able to base pair with the tRNAiMet in the primer-template initiation complex.

Amino Acid Sequence↗
PubMed1997

Heterogeneous terminal structure of Ty1 and Ty3 reverse transcripts.

A specific terminal structure of preintegrative DNA is required for transposition of retroviruses and LTR-retrotransposons. We have used an anchored PCR technique to map the 3'ends of DNA intermediates synthesized inside yeast Ty1 and Ty3 retrotransposon virus-like particles. We find that, unlike retroviruses, Ty1 replicated DNA does not have two extra base pairs at its 3'ends. In contrast some Ty3 preintegrative DNA molecules have two extra nucleotides at the 3'end of upstream and downstream long terminal repeats. Moreover we find that some molecules of replicated Ty3 DNA have more than two extra nucleotides at the 3'end of the upstream LTR. This observation could be accounted for by imprecise RNAse H cutting of the PPT sequence. The site of Ty1 and Ty3 plus-strand strong-stop DNA termination was also examined. Our results confirm that the prominent Ty1 and Ty3 plus-strand strong-stop molecules harbor 12 tRNA templated bases but also show that some Ty1 and Ty3 plus-strand strong-stop DNA molecules harbor less tRNA templated bases. We propose that these less than full length plus-strand molecules could be active intermediates in Ty retrotransposon replication.

DNA Replication↗
PubMed1997

[High dose chemotherapy with autologous stem cell transplantation].

Subsequent stem cell transplantation makes it possible to increase the dose of oncological chemotherapy by a factor of between three- and ten-fold. For primary treatment, the superiority of this approach vis-a-vis standard doses seems to be highly likely in the case of recurrent highly malignant lymphomas, metastatic mamma carcinomas and plasmacytomas. To date, however, the most favorable time point for high-dose chemotherapy has not yet been definitively established-not has the patient group most likely to benefit or the most effective combination of cytostatics to be used. For this reason, such treatment, even of these diseases, should not be applied outside of controlled studies, and must be viewed even more critically in the case of other diseases for which data from randomized studies are not yet available. Despite a relatively low overall level of toxicity, peripheral blood stem cell transplantation (PBSCT) still has a mortality rate--even in large centers--of 2 to 5%. Any such treatment should therefore be given only in controlled studies and in suitable centers.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1997

Duplication of an approximately 1.5 Mb DNA segment at chromosome 5q22 indicates the locus of a new tumour gene in nonpapillary renal cell carcinomas.

Previous karyotyping showed an unbalanced translocation between chromosome 3p11.2-p13 and chromosome 5q22 leading to duplication of chromosome 5q22-qter region in nonpapillary renal cell carcinomas. In order to determine the breakpoint at chromosome 5q22 at the molecular level, we have investigated 50 sporadic nonpapillary renal cell carcinomas from consecutive nephrectomies and 24 renal cell carcinomas obtained from two patients with von Hippel-Lindau disease. We used seven DNA markers mapped to and around the APC and MCC genes to detect allelic imbalance. We observed a duplication of chromosome 5q sequences in 11 of 23 informative sporadic tumours and in 18 of 24 hereditary tumours. We determined a breakpoint cluster between the APC and MCC genes at chromosome 5q22. In addition we have found a partial duplication of the smallest overlapping region of about 1.5 Mb sequences including the MCC gene in seven tumours without visible alteration of chromosome 5q in the karyotype. We suggest that this DNA segment harbours a gene or gene cluster, the altered dosage of which is important for the growth of nonpapillary renal cell carcinomas.

Blotting, Southern↗
PubMed1997

Host cell factor CD59 restricts complement lysis of Plasmodium falciparum-infected erythrocytes.

Here we demonstrate that components of the entire complement cascade are fixed on the surface of erythrocytes infected with the human malarial parasite Plasmodium falciparum. Despite the activation of lytic complement factors, no complement-mediated lysis of P. falciparum-infected erythrocytes occurred only in the absence of functional intrinsic CD59. These data suggest that the restriction of the complement attack of P. falciparum-infected erythrocytes is principally mediated by intrinsic host cell factors, in particular CD59.

Animals↗