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Biomedical subjects

M Baur

Publications and source records attributed to M Baur.

At least 19 recordsLinked to original sources
PubMed2005

Phase I/II study of oral etoposide plus GM-CSF as second-line chemotherapy in platinum-pretreated patients with advanced ovarian cancer.

The aim of this phase I/II study was to determine the maximum tolerated dose (MTD) and the dose-limiting toxicities of chronic oral etoposide given on days 1-10 followed by rescue with subcutaneous (s.c.) granulocyte-macrophage colony-stimulating factor (GM-CSF) on days 12-19 as second-line chemotherapy in platinum-pretreated patients (pts) with advanced ovarian carcinoma. Cohorts of three to six pts were treated with doses of oral etoposide from 750 mg m(-2) cycle(-1) escalated to 1250 mg m(-2) cycle(-1) over 10 days, every 3 weeks. Subcutaneous GM-CSF, 400 mug once daily, days 12-19, was added if dose-limiting granulocytopenia was encountered. In total, 18 pts with a median Karnofsky index of 80% (range, 70-100%) and a median time elapsed since the last platinum dose of 10 months (range, 1-24 months), 30% of whom showed visceral metastases, were treated at four dose levels (DLs) of oral etoposide on days 1-10 of each cycle as follows: DL 1, 750 mg m(-2) cycle(-1), without GM-CSF, three pts; DL 2, 1000 mg m(-2) cycle(-1), without GM-CSF, three pts; DL 3, 1000 mg m(-2) cycle(-1), with GM-CSF, six pts; and DL 4, 1250 mg m(-2) cycle(-1), with GM-CSF, six pts. All pts were assessable for toxicity and 16 pts for response. Dose-limiting toxicity (DLT) was reached at DL 4 by three of six pts, showing World Health Organization (WHO) toxicity grade 4. One patient died from gram-negative sepsis associated with granulocytopenia grade 4. Two more pts developed uncomplicated granulocytopenia grade 4. Thus, we recommend that DL 3 can be used for further phase II evaluation (i.e. oral etoposide 1000 mg m(-2) cycle(-1), days 1-10, followed by s.c. GM-CSF 400 mug, days 12-19). The clinical complete or partial responses in each patient cohort were: DL 1, one of three pts; DL 2, one of three pts; DL 3, three of five pts; and DL 4, two of five pts. In conclusion, in this phase I/II study, we defined the MTD and the dose recommended for the therapy with oral etoposide given over 10 days followed by s.c. GM-CSF in platinum-pretreated patients with advanced ovarian cancer. Our data demonstrate encouraging activity of this regimen and strongly support its further investigation in a phase II study.

Administration, Oral↗
PubMed2004

Influence of human recombinant interferon-alpha2a (rhIFN-alpha2a) on altered lymphocyte subpopulations and monocytes in Behcet's disease.

OBJECTIVE: In Behçet's disease (BD), several abnormalities of lymphocyte subpopulations have been described. Standard treatment comprises immunosuppressive drugs. We successfully treated 50 patients with ocular BD with interferon-alpha2a (IFN-alpha2a) (response rate 92%), although this is counterintuitive because IFN-alpha is immunostimulatory and can sometimes even induce autoimmune diseases such as systemic lupus erythematosus or rheumatoid arthritis. The aim of the present study was to elucidate the immunomodulatory effects that IFN-alpha might exert on peripheral blood mononuclear cells (PBMC) in BD by examining changes in the distribution of lymphocyte subpopulations under IFN-alpha2a treatment. METHODS: Fourteen patients with ocular BD were evaluated before and at weeks 4 and 24 of IFN-alpha treatment and compared with 10 healthy controls. PBMC were stained with monoclonal antibodies and measured by flow cytometry. RESULTS: Compared with the controls there is a significant elevation of monocytes (CD14(+)), CD8(+)/gammadelta T cells, CD3(+)/gammadelta T cells, natural killer (NK) cells (CD56(+)/CD16(+)) and activated/regulatory T cells (CD4(+)/CD25(+) and CD8(+)/CD25(+)) in patients with active BD before treatment with IFN-alpha2a. Numbers of naïve T cells (CD8(+)/CD45(+)RA(+)/RO(-), CD4(+)/CD45(+)RA(+)/RO(-)) were significantly lower. Under therapy, NK cells, CD8(+)/gammadelta T cells and CD3(+)/gammadelta T cells decreased significantly, whereas B cells increased. The previously reduced expression of HLA class I on monocytes in HLA-B51-positive patients rose to levels comparable to HLA-B51-negative patients. CONCLUSION: These results implicate the participation of NK cells and gammadelta T cells, especially CD8(+)/gammadelta T cells, in the pathogenesis of BD and may explain one mechanism by which IFN-alpha2a exerts therapeutic effects. Alternatively, they may result indirectly from remission induction by IFN-alpha2a. The reduced expression of HLA class I on monocytes in HLA-B*51-positive patients might reflect an impaired expression of and antigen presentation by HLA-B*51.

Adult↗
PubMed2004

[Mitochondrial A1555G mutation. Molecular genetic diagnosis in sporadic cases of non-syndromic hearing impairment].

BACKGROUND: The A1555G mutation in mitochondrial DNA is the cause of hearing impairment in about 50% of all carriers. The severity and onset of this impairment is predominantly affected by the use of aminoglycosides. PATIENTS AND METHODS: A total of 391 patients displaying sporadic, non-syndromic, mild to severe hearing impairment were analyzed for the A1555G mutation using molecular genetic methods. RESULTS: We analysed additional family members of the two patients (0.5% of the total) who had the mutation. All maternal relatives carried the mutation, but only three individuals from the two families displayed a variable sensorineural hearing loss. CONCLUSION: The A1555G mutation is infrequently involved as a genetic cause of sporadic, non-syndromic hearing impairment. Nevertheless, based on the variable clinical outcome of hearing impairment and the possibility of preventive steps, a genetic test in this patient subgroup is indicated.

DNA Mutational Analysis↗
PubMed2002

Easy and effective--web-based information systems designed and maintained by physicians: experience with two gynecological projects.

It is well established that medical information sources develop continuously from printed media to digital online sources. To demonstrate effectiveness and feasibility of decentralized performed web-based information sources for health professionals, two projects are described. The information platform of the German Working Group for Information Technologies in Gynecology and Obstetrics (AIG) and the information source concerning the German Registry for in vitro fertilization (DIR) were implemented using ordinary software and standard computer equipment. Only minimal resources and training were necessary to perform safe and reliable web-based information sources with a high correlation of effectiveness in costs and time exposure.

Data Collection↗
PubMed2002

Effective salvage therapy with carboplatin/mitomycin C in metastatic breast cancer.

BACKGROUND: Alternative and effective drug regimens in patients with metastatic breast cancer progressing after adriamycin- and taxoid-containing regimens are urgently needed. PATIENTS AND METHODS: In a phase II trial, 43 heavily pretreated patients with metastatic breast cancer were treated with both carboplatin 200 mg/m(2) i.v. and mitomycin C 10 mg/m(2) i.v. on day 1 every 4 weeks. In case of granulocytopenia or thrombocytopenia below grade 3 according to NCI-CTC, the carboplatin dosage was escalated to 300, 400, and 450 mg/m(2) in the next treatment cycle. RESULTS: During the first 3 cycles the dose intensity of carboplatin could be increased from a mean of 50 to 74 mg/m(2)/week. Beyond this value the carboplatin dose intensity decreased because of hematotoxicity. Based on an intention-to-treat analysis, 9 of 43 patients responded to therapy (21%; 95% CI = 10.04-36.04) including 2 complete and 7 partial responses. 15 patients had no change, 13 progressed, and 6 patients were considered nonevaluable. The median time to progression was 3 (range 0-12) months. NCI-CTC grade 3 or 4 granulocytopenia was observed in 14 patients, grade 3 or 4 thrombocytopenia occurred in 32, grade 3 infections in 3, grade 3 hemorrhage in 1, and grade 3 cardiac dysrhythmias in 1 of the patients. CONCLUSIONS: In anthracycline/ taxoid-pretreated patients, salvage treatment with a combination of carboplatin and mitomycin C seems to be effective and associated with foreseeable toxicity. Based on our results with an intraindividual dose escalation of carboplatin, a dosage of 300 mg/m(2) in combination with mitomycin C 10 mg/m(2) every 4 weeks seems to represent a recommendable starting dose for future studies.

Adult↗
PubMed2001

Docetaxel extravasation.

We report on an accidental extravasation of docetaxel given intravenously as chemotherapy in a cancer patient. The extravasate was immediately diluted subcutaneously with saline, in addition to which hypothermia (ice-packs) was implemented and topical dimethylsulfoxide (DMSO) was applied three times every 45 min. Corticosteroids and diclofenac were also administered. Dermatitis developed immediately but had disappeared within 24 h. Notably, dermatopathological changes were absent on days 2-4, minimal on day 5, and increased thereafter. Dermatitis developed as a late symptom, resulting in brown discoloration and skin hyperplasia. No plastic surgical intervention was necessary. We propose that isotonic saline, topical DMSO and local hypothermia may have restricted the inflammation and tissue necrosis induced by the extravasation of docetaxel. Repetitive topical application of DMSO beyond the day of extravasation had no additional benefit.

Aged↗
PubMed2001

Prognostic significance of liver metastases as first site of generalisation in patients with breast cancer--a retrospective analysis.

Of 672 patients with metastatic breast cancer, 24 evaluable patients with primary liver metastases were analysed with regard to their prognostic variables and survival. In 50% of these patients, liver metastases were found within the first 8.5 months after the diagnosis of breast cancer. The median survival of 10 months (range 0-60+ months) was extremely unfavourable. The median survival of hormone-receptor-positive patients (11 months) was significantly longer than that of patients with hormone-receptor-negative tumours (4 months) (P = 0.025). Patients with elevated lactate dehydrogenase (LDH), glutamic-oxaloacetic transaminase (GOT) (> 50 U/I), or bilirubin levels at diagnosis had a significantly shorter median survival than patients with normal laboratory parameters (P = 0.001, P = 0.047, and P = 0.056, respectively). This retrospective study confirms the short survival time for breast cancer patients with liver metastases as initial site of relapse. Hormone-receptor status and the laboratory parameters LDH, GOT, and bilirubin were identified as important prognostic factors for survival.

Breast Neoplasms↗
PubMed2001

Family-based association test method: age of onset traits and covariates.

We apply different family-based association test (FBAT) statistics for age of onset traits to the Genetics Analysis Workshop 12, problem 2 data. To evaluate different FBAT statistics we used the software package FBAT, which allows one to evaluate any test statistic that can be expressed as the sum of products between an arbitrary function of an offspring's genotype with an arbitrary function of the offspring's phenotype even if there are missing parental information. For single nucleotide polymorphisms (SNPs) in gene 1, our age-of-onset FBAT test based on the exponential model is significantly more powerful than the test by Mokliatchouk et al. [Hum Hered 51:46-53, 2000], which is based on the Cox model. We suggest incorporating covariates into FBAT statistics by replacing the trait values by their regression residuals. For the age of onset trait statistics we find that deviance residuals have much more power than "plain" martingale residuals. We discuss why for SNPs in gene 1, the usual affectation status trait, which underlies the transmission disequilibrium test (TDT), has higher power than the age-of-onset trait. We find only weak evidence (p = 0.0002) that marker D06G032 is associated with the affectation status.

Adult↗
PubMed1999

Organotypic keratinocyte cocultures in defined medium with regular epidermal morphogenesis and differentiation.

Skin equivalents formed by keratinocytes cocultured with fibroblasts embedded in collagen lattices represent promising tools for mechanistic studies of skin physiology, for pharmacotoxicologic testing, and for the use as skin substitutes in wound treatment. Such cultures would be superior in defined media to avoid interference with components of serum or tissue extracts. Here we demonstrate that a defined medium (supplemented keratinocyte defined medium) supports epidermal morphogenesis in organotypic cocultures equally well as serum-containing medium (mixture of Ham's F12 and Dulbecco's modified Eagle's medium), as documented by hallmarks of the epidermal phenotype studied by immunofluorescence and electron microscopy. In both cases regularly structured, orthokeratinized epithelia evolved with similar kinetics. Morphology in mixture of Ham's F12 and Dulbecco's modified Eagle's medium was slightly hyperplastic, and keratins 1 and 10 synthesis less co-ordinated than in supplemented keratinocyte defined medium, but a consistently inverted sequence of expression of keratins 1 and 10 was found in either medium. The late differentiation markers filaggrin, involucrin, keratin 2e, and transglutaminase 1 corresponded in their typical distribution in upper suprabasal layers. Keratin 16 persisted under both conditions indicating the activated epidermal state. Keratinocyte proliferation was comparable in both media, whereas fibroblast multiplication and proliferation was delayed and reduced in supplemented keratinocyte defined medium. In both media, ultrastructural features of epidermal differentiation as well as reconstitution of a basement membrane occurred similarly. Immature lamellar bodies and cytoplasmatic vacuoles, however, indicated an impaired lipid metabolism in supplemented keratinocyte defined medium. Nevertheless, these defined organotypic cocultures provide a suitable basis for in vitro skin models to study molecular mechanisms of tissue homeostasis and for use in pharmacotoxicologic testing.

Animals↗
PubMed1998

Cyclopropane-derived peptidomimetics. Design, synthesis, evaluation, and structure of novel HIV-1 protease inhibitors.

Toward establishing the general efficacy of using trisubstituted cyclopropanes as peptide mimics to stabilize extended peptide structures, the cyclopropanes 20a-d were incorporated as replacements into 9-13, which are analogues of the known HIV-1 protease inhibitors 14 and 15. The syntheses of 20a-d commenced with the Rh2[5(S)-MEPY]4-catalyzed cyclization of the allylic diazoesters 16a-d to give the cyclopropyl lactones 17a-d in high enantiomeric excess. Opening of the lactone moiety using the Weinreb protocol and straightforward refunctionalization of the intermediate amides 18a-d gave 20a-d. A similar sequence of reactions was used to prepare the N-methyl-2-pyridyl analogue 28. Coupling of 20a-d and 28 with the known diamino diol 22 delivered 9-13. Pseudopeptides 9-12 were found to be competitive inhibitors of wild-type HIV-1 protease in biological assays having Kis of 0.31-0.35 nM for 9, 0.16-0.21 nM for 10, 0.47 nM for 11, and 0.17 nM for 12; these inhibitors were thus approximately equipotent to the known inhibitor 14(IC50 = 0.22 nM) from which they were derived. On the other hand 13 (Ki = 80 nM) was a weaker inhibitor than its analogue 15 (Ki = 0.11 nM). The solution structures of 9 and 10 were analyzed by NMR spectroscopy and simulated annealing procedures that included restraints derived from homo- and heteronuclear coupling constants and NOEs; because of the molecular symmetry of9 and 10, a special protocol to treat the NOE data was used. The final structure was checked by restrained and free molecular dynamic calculations using an explicit DMSO solvent box. The preferred solution conformations of 9 and 10 are extended structures that closely resemble the three-dimensional structure of 10 bound to HIV-1 protease as determined by X-ray crystallographic analysis of the complex. This work convincingly demonstrates that extended structures of peptides may be stabilized by the presence of substituted cyclopropanes that serve as peptide replacements. Moreover, the linear structure enforced in solution by the two cyclopropane rings in the pseudopeptides 9-12 appears to correspond closely to the biologically active conformation of the more flexible inhibitors 14 and 15. The present work, which is a combination of medicinal, structural, and quantum chemistry, thus clearly establishes that cyclopropanes may be used as structural constraints to reduce the flexibility of linear pseudopeptides and to help enforce the biologically active conformation of such ligands in solution.

Binding Sites↗
PubMed1998

13C-NOESY-HSQC with Split Carbon Evolution for Increased Resolution with Uniformly Labeled Proteins.

Two new pulse sequences are presented for the recording of 2D 13C-HSQC and 3D 13C-NOESY-HSQC experiments, containing two consecutive carbon evolution periods. The two periods are separated by a z-filter which creates a clean CxHz-quantum state for evolution in the second period. Each period is incremented (in a non-constant-time fashion) only to the extent that the defocusing of carbon inphase magnetization through J-coupling with neighboring carbons remains insignificant. Therefore, 13C homonuclear J-couplings are rendered ineffective, reducing the loss of signal and peak splitting commonly associated with long 13C evolution times. The two periods are incremented according to a special acquisition protocol employing a 13C-13C gradient echo to yield a data set analogous to one obtained by evolution over the added duration of both periods. The spectra recorded with the new technique on uniformly 13C-labeled proteins at twice the evolution time of the standard 13C-HSQC experiment display a nearly twofold enhancement of resolution in the carbon domain, while maintaining a good sensitivity even in the case of large proteins. Applied to the IIAMan protein of E. coli (31 kDa), the 13C-HSQC experiment recorded with a carbon evolution time of 2 x 8 ms showed a 36% decrease in linewidths compared to the standard 13C-HSQC experiment, and the S/N ratio of representative cross-peaks was reduced to 40%. This reduction reflects mostly the typical loss of intensity observed when recording with an increased resolution. The 13C-NOESY-HSQC experiment derived from the 13C-HSQC experiment yielded additional NOE restraints between resonances which previously had been unresolved. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

Epidermal differentiation and basement membrane formation by HaCaT cells in surface transplants.

The immortal human keratinocyte line HaCaT has been employed in many studies as paradigm for epidermal keratinocytes. In order to demonstrate its potential to form stable epidermal structures in response to connective tissue, this was challenged in surface transplants on nude mice, where normal keratinocytes rebuild a typical epidermis within two weeks. During the initial regeneration phase (day 1-4) multilayered but poorly organized epithelia formed with proliferating cells in all layers in analogy to normal keratinocytes. Similarly, with tissue consolidation (around day 7) proliferation was reduced and restricted to cells in basal position marked by keratin K14 and beta1-integrin immunostaining. The strong suprabasal reaction for K1 and K10, the appearance of the late markers K2e, filaggrin and loricrin as well as the polarized distribution of alpha2beta1 and alpha3beta1 indicated advancing tissue normalization (day 14). Keratinization further improved at around three weeks switching from the initial parakeratotic to the regular orthokeratotic type which was prominent at six weeks. Accordingly, most ultrastructural features typical for epidermis or normal keratinocyte grafts were detectable including a complete basement membrane (BM) with regular attachment structures. Matrix- and BM-components appeared sequentially with marked linear deposition of laminin-5 (day 4) followed by accumulation of collagen-IV and 'classical' BM-laminin between one and two weeks. With the general codistribution of integrin alpha6beta4 and BM-molecules (day 14) collagen-VII lining of BM became prominent, while epithelium and host connective tissue were still separated by the collagen matrix. In accordance with the delayed orthokeratinization, wound-matrix molecules (fibronectin, tenascin) persisted longer than in normal keratinocyte transplants. Finally, grafts of long-term passaged (no. 310) cells demonstrated a remarkable stability in the expression of epidermal markers. Thus, the immortalized HaCaT cells reveal a generally high competence to realize an epidermal phenotype in a natural environment and appear therefore qualified for in vitro studies on structural and regulatory aspects of keratinocyte physiology and pathology.

Animals↗
PubMed1997

A comparison of recombinant hirudin with a low-molecular-weight heparin to prevent thromboembolic complications after total hip replacement.

BACKGROUND: Patients who undergo total hip replacement have a high risk of thromboembolic complications. Recombinant hirudin (desirudin), a specific inhibitor of thrombin, represents a new development in antithrombotic therapy. We compared the efficacy and safety of desirudin with those of a low-molecular-weight heparin (enoxaparin) for the prevention of thromboembolic complications in patients undergoing primary total hip replacement. METHODS: Both treatments, which were assigned in a randomized, double-blind manner, were started preoperatively: enoxaparin on the evening before surgery, and desirudin within 30 minutes before the start of surgery. The dose of desirudin was 15 mg subcutaneously twice daily, and the dose of enoxaparin was 40 mg subcutaneously once daily. The duration of treatment was 8 to 12 days. Deep-vein thrombosis was verified by bilateral venography performed at the end of the treatment period or earlier, if there were clinical signs of deep-vein thrombosis. RESULTS: At 31 centers in 10 European countries, 2079 eligible patients were randomly assigned to receive desirudin or enoxaparin. A total of 1587 patients were included in the primary analysis of efficacy. In the desirudin group, as compared with the enoxaparin group, there was a significantly lower rate of proximal deep-vein thrombosis (4.5 vs. 7.5 percent, P=0.01; relative reduction in risk, 40.3 percent) and a lower overall rate of deep-vein thrombosis (18.4 vs. 25.5 percent, P=0.001; relative reduction in risk, 28.0 percent). The safety profiles were similar in the two treatment groups. CONCLUSIONS: When administered 30 minutes before total hip replacement surgery, desirudin is more effective than enoxaparin in preventing deep-vein thrombosis.

Adolescent↗
PubMed1997

The meiotic recombination hot spot created by the single-base substitution ade6-M26 results in remodeling of chromatin structure in fission yeast.

The G -->T transversion mutation, ade6-M26, creates the heptanucleotide sequence ATGACTG, which lies close to the 5' end of the open reading frame of the ade6 gene in Schizosaccharomyces pombe. The mutation generates a meiosis-specific recombination hot spot and a binding site for the Mts1/Mts2 protein. We examined the chromatin structure at the ade6 locus in the M26 strain and compared it to that of the wild-type and hot spot-negative control M375. Micrococcal nuclease (MNase) digestion and indirect end-labeling methods were applied. In the M26 strain, we detected a new MNase-hypersensitive site at the position of the M26 mutation and no longer observed the phasing of nucleosomes seen in the wild-type and the M375 strains. Quantitative comparison of MNase sensitivity of the chromatin in premeiotic and meiotic cultures revealed a small meiotic induction of MNase hypersensitivity in the ade6 promoter region of the wild-type and M375 strains. The meiotic induction of MNase hypersensitivity was enhanced significantly in the ade6 promoter region of the M26 strain and also occurred at the M26 mutation site. The formation of the MNase-sensitive region around the heptamer sequence was abolished by the introduction of single-nucleotide substitutions in the heptamer sequence, which also abolish hot spot activity and binding of Mts1/Mts2. These data suggest that Mts1/Mts2 binding to the heptamer sequence results in a chromatin structure suitable for the recruitment of a meiosis-specific recombination function or functions.

Chromatin↗
PubMed1997

Octreotide combined with goserelin in the therapy of advanced pancreatic cancer--results of a pilot study and review of the literature.

The two hormone analogues octreotide and goserelin have been shown to decelerate growth of human pancreatic cancer in vitro and in vivo. The objective of this pilot study was to investigate the efficacy and toxicity of the combination of these two agents in patients with advanced pancreatic cancer. Octreotide was injected subcutaneously in dosages increasing weekly, starting with 50 micrograms twice daily, until the level of maintenance therapy of 500 micrograms three times a day was reached. In addition, 3.8 mg goserelin acetate was administered subcutaneously at monthly intervals. A median of 7 cycles (range 1-27 cycles) were applied; 13 out of 14 patients entered into the study were evaluable for response and all 14 were evaluated for toxicity. In one patient with initially non-resectable pancreatic cancer, systemic therapy yielded a partial remission lasting 9 months. The degree of tumour regression then allowed a consecutive macroscopic radical tumour resection followed by an additional 6 months of no evidence of disease while the same drug combination was continued. In an additional 9 patients, no change of disease was observed, in some cases for a remarkably long time (up to 27 months). Nevertheless, the objective response rate of 7% (95% confidence interval 0 +/- 21%) was low. In 5 patients a clear improvement in their performance status was seen soon after the start of therapy; 3 patients showed progression of the disease at first evaluation or earlier and 1 patient was not evaluable at the time of study assessment. According to the product-limit method of Kaplan and Meier, the time to progression was 3.0 +/- 1.8 months [median +/- asymptotic standard error (ASE)] and overall survival was 6.0 +/- 1.5 months (median +/- ASE). Toxicity was rare and only of mild to moderate degree. Overall, the regimen under investigation did not meet the criteria for sufficient antitumoural effectiveness. Nevertheless, this study reinforces the concept that pancreatic cancer is principally responsive to endocrine therapy and therefore the further investigation of hormonal manipulation seems worth while in the future.

Aged↗