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M Winkelmann

Publications and source records attributed to M Winkelmann.

At least 19 recordsLinked to original sources
PubMed2005

Performance of calorimetric methods for the investigation of microbial systems in combination with additional sensors.

Calorimetric methods are used in combination with online oxygen measurement (using an amperometric sensor) and determination of the optical density (using a fibre optic sensor) to investigate microbial growth behaviour. The calorimetric curves of different batch experiments show a characteristic and reproducible course. Changes in the slope of the DeltaT-time curves indicate the effects of limiting factors on the microbial activity during the cultivation. A first limitation could be correlated with the depletion of oxygen in the medium; a second correlates with the depletion of the carbon source. Measurements of optical density in some cases provide reliable information about the growth of a microorganism culture. Our measurements show a good correlation of the universal calorimetric signal (heat-time curve) to the signal of the miniaturised photometric (OD) sensor.

Calorimetry↗
PubMed2003

Chemically patterned, metal oxide based surfaces produced by photolithographic techniques for studying protein- and cell-surface interactions I: Microfabrication and surface characterization.

Chemical patterns on smooth wafer substrates comprising areas with two different metals have been produced by vacuum metal deposition and photolithographic techniques. The combination of metals has been chosen from the series titanium (Ti), aluminium (Al), vanadium (V) and niobium (Nb), producing patterns (dots and stripes with dimensions of 50, 100 and 150 micrometer) with one of the metals as the background and with the second metal (foreground pattern) deposited on the background metal. The structure and chemical composition of the patterned surfaces were evaluated by scanning electron microscopy, X-ray photoelectron spectroscopy and imaging time-of-flight secondary-ion mass spectrometry. The surfaces proved to be geometrically well defined with the expected surface-chemical composition, i.e. a surface oxide (passive) film essentially composed of TiO(2),Al(2)O(3),V(2)O(5), or Nb(2)O(5). Ti/Ti patterned surfaces were produced as controls and found to show no chemical composition contrast. The surface roughness of the pattern was greater than that of the background by a factor of 2-3, but was still extremely smooth with Ra<2nm. The patterns serve as model surfaces for studying in vitro the behaviour of cells as well as the adsorption of serum proteins on different metal oxides, which will be reported in a companion paper. These surfaces can be used to compare and contrast the response of osteoblasts to Ti and other alloy components, such as Al, V, or Nb, which are used in load-bearing medical implants.

Aluminum↗
PubMed2003

Chemically patterned, metal-oxide-based surfaces produced by photolithographic techniques for studying protein- and cell-interactions. II: Protein adsorption and early cell interactions.

Protein adsorption and adhesion of primary human osteoblasts on chemically patterned, metal-oxide-based surfaces comprising combinations of titanium, aluminium, vanadium and niobium were investigated. Single metal samples with a homogeneous surface and bimetal samples with a surface pattern produced by photolithographic techniques were used. The physical and chemical properties of the samples have been extensively characterised and are presented in a companion paper. Here, we describe their properties in terms of cell responses during the initial 24h of cell culture. Regarding the cell number and activity there was no significant difference between any of the single metal surfaces. However the morphology of cells on vanadium surfaces became spindle-like. In contrast to the behaviour on single metal samples, cells exhibited a pronounced reaction on bimetallic surfaces that contained aluminium. Cells tended to stay away from aluminium, which was the least favoured metal in all two-metal combinations. An initial cell alignment relative to the pattern geometry was detectable after 2h and was fully developed after 18h of incubation. The organisation of f-actin and microtubules as well as the localisation of vinculin were all more pronounced on non-aluminium regions. We hypothesised that the differences in cell response could be associated with differences in the adsorption of serum proteins onto the various metal oxides. Protein adsorption experiments were performed using microscopy in conjunction with immunofluorescent stains. They indicated that both fibronectin and albumin adsorption were significantly greater on the non-aluminium regions, suggesting that differences in cellular response correlate with a modulation of the concentration of serum proteins on the surface.

Adsorption↗
PubMed2000

Elevated DNA sequence diversity in the genomic region of the phosphatase PPP2R3L gene in the human pseudoautosomal region.

The evolution, inheritance and recombination rate of genes located in the pseudoautosomal region 1 (PAR1) is exceptional within the human genome. Pseudoautosomal genes are identical on X and Y chromosomes and are not inherited in a sex linked manner. Due to an obligatory recombination event in male meiosis, pseudoautosomal genes are exchanged frequently between X and Y chromosomes. During the isolation, characterization and sequencing of a novel gene PPP2R3L, which was classified by sequence homology as a novel member of the protein phosphatase regulatory subunit families, it became apparent that cosmids of different origin harboring this gene are highly polymorphic between individuals, both at the nucleotide level and in the number.

Amino Acid Sequence↗
PubMed1997

Pseudoautosomal deletions encompassing a novel homeobox gene cause growth failure in idiopathic short stature and Turner syndrome.

Growth retardation resulting in short stature is a major concern for parents and due to its great variety of causes, a complex diagnostic challenge for clinicians. A major locus involved in linear growth has been implicated within the pseudoautosomal region (PAR1) of the human sex chromosomes. We have determined an interval of 170 kb of DNA within PAR1 which was deleted in 36 individuals with short stature and different rearrangements on Xp22 or Yp11.3. This deletion was not detected in any of the relatives with normal stature or in a further 30 individuals with rearrangements on Xp22 or Yp11.3 with normal height. We have isolated a homeobox-containing gene (SHOX) from this region, which has at least two alternatively spliced forms, encoding proteins with different patterns of expression. We also identified one functionally significant SHOX mutation by screening 91 individuals with idiopathic short stature. Our data suggest an involvement of SHOX in idiopathic growth retardation and in the short stature phenotype of Turner syndrome patients.

Adolescent↗
PubMed1997

Abnormal XY interchange between a novel isolated protein kinase gene, PRKY, and its homologue, PRKX, accounts for one third of all (Y+)XX males and (Y-)XY females.

XX males and XY females have a sex reversal disorder which can be caused by an abnormal interchange between the X and the Y chromosomes. We have isolated and characterized a novel gene on the Y chromosome, PRKY. This gene is highly homologous to a previously isolated gene from Xp22.3, PRKX, and represents a member of the cAMP-dependent serine threonine protein kinase gene family. Abnormal interchange can occur anywhere on Xp/Yp proximal to SRY. We can show that abnormal interchange happens particularly frequently between PRKX and PRKY. In a collection of 26 XX males and four XY females, between 27 and 35% of the interchanges take place between PRK homologues but at different sites within the gene. PRKY and PRKX are located far from the pseudoautosomal region where XY exchange normally takes place. The unprecedented high sequence identity and identical orientation of PRKY to its homologous partner on the X chromosome, PRKX, explains the high frequency of abnormal pairing and subsequent ectopic recombination, leading to XX males and XY females and to the highest rate of recombination outside the pseudoautosomal region.

Aneuploidy↗
PubMed1997

FISH localization of the human Y-homolog of protein kinase PRKX (PRKY) to Yp11.2 and two pseudogenes to 15q26 and Xq12-->q13.

Recently, we reported the isolation of a new subfamily of serine-threonine protein kinases. This subfamily was shown to consist of at least four members. Sequencing and FISH mapping of all 4 members now reveals that the Y-homolog (PRKY) of the previously mapped PRKX gene (Xp22.3) is located in Yp11.2, in close vicinity to AMELY. The other two copies reside on Xq12-->q13 (PRKXP2) and 15q26 (PRKXP1, containing CA repeat STS D15S87) and represent pseudogenes.

Base Sequence↗
PubMed1996

Association of primary renal non-Hodgkin's lymphoma with mesangioproliferative glomerulonephritis.

A 27-year-old male developed nonoliguric renal failure. Renal biopsy of the left kidney showed infiltration by a diffuse large-cell non-Hodgkin's lymphoma (NHL). Laparoscopy, CT scans of the abdomen and thorax, and bone-marrow biopsy revealed no further manifestations of lymphoma. Primary renal NHL was diagnosed. The patient attained complete remission with cyclophosphamide, adriamycin, vincristine, and prednisone (CHOP) chemotherapy and remained disease-free for 13 years. Eight years after his first presentation, the patient developed acute oliguric renal failure with nephrotic syndrome. Mesangioproliferative glomerulonephritis was diagnosed in a biopsy of the left kidney. Chronic hemodialysis was required until cadaver kidney transplantation was successfully performed 5 years later. Although the association of NHL and glomerulonephritis has been described several times before, to our knowledge this is the first report of glomerulonephritis in primary renal lymphoma.

Adult↗
PubMed1995

The human protein kinase gene PKX1 on Xp22.3 displays Xp/Yp homology and is a site of chromosomal instability.

We have isolated a gene, PKX1, by virtue of its position within the candidate region for chondrodysplasia punctata in Xp22.3. Although data from one patient render it unlikely that PKX1 is the CDPX gene, this gene shows several interesting features. First, PKX1 appears to encode a novel type of human protein kinase that is related to the catalytic subunit of cAMP-dependent protein kinases and has striking homology to the DC2 protein kinase from Drosophila melanogaster. Second, PKX1 is part of a family of at least four genes or pseudogenes, of which three map to the human sex chromosomes. In contrast to all other genes from the X-specific region of Xp22.3, PKX1 has a homologue on Yp rather than Yq. This is intriguing as it indicates that the single pericentric inversion event hypothesized to have occurred during primate evolution is not sufficient to explain the present X/Y-homology pattern of Xp22.3. Third, we have characterized patients with different chromosomal rearrangements in Xp22.3 or Yp and show that a high proportion of these have occurred within the PKX1 locus. This suggests that the PKX1 gene, besides harbouring a previously described hot-spot for illegitimate Xp/Yp-recombination, contains additional sequences predisposing to chromosomal breakage events.

Amino Acid Sequence↗
PubMed1994

Serum deoxythymidine kinase in myelodysplastic syndromes.

BACKGROUND: Previous studies have shown that serum levels of deoxythymidine kinase (sTK) provide useful prognostic information in various malignancies, such as Hodgkin's disease, non-Hodgkin's lymphomas, multiple myeloma, and acute myeloid leukemia (AML). METHODS: Using a radioenzyme assay, the authors determined sTK in 146 patients with primary myelodysplastic syndromes (MDS). Morphologic subtypes were refractory anemia (RA) in 18 patients, RA with ring sideroblasts (RARS) in 24, RA with excess of blasts (RAEB) in 41, RAEB in transformation (RAEB/T) in 29, and chronic myelomonocytic leukemia (CMML) in 34. RESULTS: Enzyme levels ranged from 1.1 to 829 U/microliters. One hundred fifteen (79%) patients had elevated sTK levels (more than 5 U/microliters) at the time of diagnosis. In advanced stages of MDS (RAEB, CMML, and RAEB/T) enzyme activities were higher than in early stages (RA and RARS) (P < 0.05). However, sTK levels were not correlated with the percentage of medullary blast cells. Among other parameters tested, the best correlation with sTK was found for serum lactate dehydrogenase (LDH) activity (r = 0.29; P < 0.0005). As shown by life table analysis, sTK activity at diagnosis provided useful information regarding the prognosis of patients. For patients with sTK levels of less than 10 U/microliters, actuarial survival after 2 years was 65%, compared with 33% for those with enzyme values of 10 U/microliters or greater. The 5-year cumulative survival rates were 34% and 14%, respectively (P < 0.0005). However, sTK levels at diagnosis were not useful for predicting transformation to AML. Nine of 61 (15%) patients with sTK of less than 10 U/microliters had AML develop, whereas 15 of 57 (26%) patients with sTK of 10 U/microliters or greater had disease progress to acute leukemia (chi-square, 1.64; P = 0.2). CONCLUSIONS: Considering the lack of correlation with bone marrow blasts, the authors conclude that increased sTK levels in MDS are primarily attributable to intramedullary destruction of hematopoietic precursors and do not reflect the leukemic blast cell burden. This appears similar to the ineffective hematopoiesis of vitamin B12 deficiency, which is associated with elevated levels of sTK and LDH. The data suggest that sTK is a prognostic parameter that can be used to predict the survival of patients with MDS. However, multivariate analysis shows that the predictive value of sTK is not superior to that of LDH.

Adolescent↗
PubMed1994

Results of conventional-dose cytosine arabinoside and idarubicin in elderly patients with acute myeloid leukemia.

Conventional-dose Ara-C (200 mg/m2 d 1-5) combined with idarubicin (12 mg/m2 d 1-3) was employed as remission induction and consolidation therapy in 23 elderly AML patients with a median age of 66 years (range, 60-75) with AML according to the FAB criteria (M1 n = 3, M2 n = 10, M4 n = 6, M5 n = 2, M6 n = 2), eligible for the study. In seven patients earlier MDS had been documented by previous bone marrow aspirates. The CR rate after one induction course was 65% (15/23). Toxicity was acceptable, with four patients dying during the chemotherapy-induced hypoplasia (4/23). Although 80% of the CR patients received two additional cycles of Ara-C and idarubicin as consolidation therapy, only two patients are still in continuous complete remission more than 12 months after achieving CR. The median disease-free survival of the CR patients was 11.5 months and the median survival of the entire group was 10 months. We conclude that conventional dose Ara-C/idarubicin is an effective protocol for inducing complete remission in elderly patients with AML, but that consolidation therapy consisting of two courses of the same regimen does not produce a relevant rate of long-term disease-free survival.

Acute Disease↗
PubMed1992

Treatment results of the thioether lipid ilmofosine in patients with malignant tumours.

In a multicentre study patients with liver metastases stratified to the histology of the primary tumour were investigated. A total of 102 patients with colorectal adenocarcinoma, non-small-cell lung cancer, pancreatic cancer, primary liver carcinoma and malignant melanoma were treated with the thioether lipid ilmofosine. The drug was administered orally as a tablet at a dosage of 150-300 mg/day (75 mg/tablet). The tolerability of ilmofosine was poor. There was a dose-limiting gastrointestinal toxicity with nausea, vomiting and loss of appetite (WHO grade II-IV) in 67% of patients. During the period of therapy (1-29 weeks, 8.5 weeks mean) no complete remission and no partial response were observed. We thus conclude that treatment with oral ilmofosine is not effective in patients with liver metastases due to various malignancies.

Adenocarcinoma↗
PubMed1991

A randomized controlled trial of adjuvant immunotherapy (murine monoclonal antibody 494/32) in resectable pancreatic cancer.

In a prospective randomized multicentric trial, 61 patients from six hospitals with resectable pancreatic cancer were recruited between 1987 and 1989. All patients underwent a Whipple resection. Two weeks after surgery, the patients were randomized to be given either intravenous (IV) treatment with 370 mg (100 mg loading dose, 9 x 30 mg continuing within 10 days) of monoclonal antibody (MoAb) 494/32 (Behringwerke AG, Marsburg, Germany) or no additional anti-cancer treatment. This murine immunoglobulin (Ig) G1 antibody has been shown to strongly bind to human pancreatic cancer cells and to induce an antibody-dependent cellular cytotoxicity (ADCC). Both study groups were well matched with respect to age, sex, tumor staging, and grading. Six patients suffered from minor toxicity (vomiting and abdominal pain) after immunotherapy. Ten months after the end of the recruitment period, 65% and 53% of the patients in the treatment and control groups, respectively, had died. Of the living patients, 60% and 53% are alive with recurrent or progressive cancer disease. Median survival time was 428 days (range, 248 to 510 days) and 386 days (range, 296 to 509 days) in the treatment and control groups, respectively. The authors concluded that repeated IV treatment with the antibody 494/32 is not helpful in resectable pancreatic cancer. This study provides the first controlled data on passive immunotherapy in solid cancer.

Adult↗