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Biomedical subjects

M Kaufmann

Publications and source records attributed to M Kaufmann.

At least 145 records · Page 8Linked to original sources
PubMed1998

New endocrine approaches in the treatment of breast cancer.

As a result of tamoxifen becoming the first endocrine compound with proven activity in breast cancer, a. broad spectrum of new substances have been tested and several are now available for clinical use. New pure antiestrogens show no estrogenic activity as a result of different receptor binding, and some other derivatives of tamoxifen demonstrate varied toxicity profiles. The second and third generation of aromatase inhibitors can selectively inhibit the aromatase enzyme in the peripheral tissue and perhaps even in tumor cells. Gonadotrophin-releasing hormone (GnRH)-analogues can suppress ovarian function in premenopausal patients and thus prevent surgical ovarectomy. The value of a new group of anti-progestional substances has not yet been clarified. In this overview the most important compounds are reviewed for efficacy and toxicity in breast cancer patients.

Antineoplastic Agents, Hormonal↗
PubMed1998

Luteinizing hormone-releasing hormone analogues in early breast cancer: updated status of ongoing clinical trials.

In the year 2000, the ongoing meta-analysis of the Early Breast Cancer Trialists' Collaborative Group will be updated to include additional data from over 4000 patients treated with luteinizing hormone-releasing hormone analogues, principally goserelin. Four major international trials are currently in progress to evaluate the safety and efficacy of goserelin in comparison with the current standard treatments in early breast cancer, which are chemotherapy or tamoxifen. This paper provides an outline of the protocols and main objectives of the Zoladex Early Breast Cancer Research Association (ZEBRA) trial (goserelin versus cyclophosphamide-methotrexate-5-fluorouracil [CMF]), the Cancer Research Campaign (CRC) trial (goserelin versus tamoxifen versus the combination of goserelin and tamoxifen versus no further treatment), the International Breast Cancer Study Group (IBCSG) VIII trial (goserelin versus CMF versus CMF followed by goserelin) and the Eastern Cooperative Oncology Group (ECOG)/South Western Oncology Group (SWOG) trial (cyclophosphamide-doxorubicin-5-fluorouracil [CAF] versus CAF followed by goserelin versus CAF followed by goserelin plus tamoxifen). Preliminary results are expected from the CRC trial in 1998 and from the ZEBRA and ECOG/SWOG trials in 1999. Results from the wide range of comparator regimens, treatment durations and patient subgroups investigated in these trials will greatly increase the clinical database and should help to define the optimum role for goserelin in the treatment of early breast cancer in premenopausal women.

Antineoplastic Agents, Hormonal↗
PubMed1998

Propofol-induced relaxation of rat mesenteric arteries: evidence for a cyclic GMP-mediated mechanism.

Experiments were designed to evaluate whether guanosine 3',5'-cyclic monophosphate (cGMP)-mediated mechanisms contribute to vasodilation via propofol in rat mesenteric resistance arteries. Ring segments were suspended in the myograph system for isometric tension recording, and responses to propofol were tested in the presence and absence of methylene blue (MB), an inhibitor of guanylate cyclase. At concentrations > or = 1 microM, propofol caused concentration-dependent relaxation of vessel rings precontracted with U46619 (a thromboxane analog). The effect was not affected by N-monomethyl-L-arginine (L-NMMA; 50 microM). MB (5 microM) reversed propofol-induced vasodilation by 30% (p < 0.001). In contrast, MB has no effect on nifedipine-inhibited vasocontraction. The propofol-induced relaxation was further tested in rings incubated in Ca2+-free solution. U46619-induced contractions were significantly reduced by propofol (40 microM) but not by nifedipine (1 microM). Propofol reduced to a similar degree the contractions obtained to exogenously added calcium chloride in the absence and the presence of MB. Furthermore, propofol (10-100 microM) increased cGMP content in cultured bovine vascular smooth-muscle cells. Soluble guanylate cyclase inhibitors, such as MB and LY83583, attenuated this effect. This investigation suggests that propofol-induced relaxations in small arteries, in addition to inhibition of calcium influx, are mediated by increases of cGMP in the smooth muscle cells.

Animals↗
PubMed1998

Apparent increased prevalence of high-level aminoglycoside-resistant Enterococcus durans resulting from false identification by a semiautomated software system.

Identification of enterococci by using a semiautomated system (PASCO; Difco Laboratories, Detroit, Mich.) in the AHEPA University Hospital, Thessaloniki, Greece, revealed a high proportion of Enterococcus durans, particularly among isolates highly resistant to gentamicin and streptomycin. When 14 isolates were further tested by a conventional biochemical scheme and by PCR, all were reidentified as Enterococcus faecalis. Antibiotic resistance and pulsed-field gel electrophoresis patterns showed that unrelated strains were misidentified.

Anti-Bacterial Agents↗
PubMed1998

[Preoperative chemotherapy of breast carcinoma].

Preoperative chemotherapy represents the standard procedure in inflammatory breast cancer. However, only recently it could be demonstrated that preoperative chemotherapy is beneficial even for patients with operable primary breast cancer. The number of breast conserving surgeries could be increased significantly. Furthermore this in vivo chemosensitivity assay can provide important prognostic as well as predictivy informations. Preoperative chemotherapy is not associated with an increased risk for the patients as outcome is similar to patients with conventional adjuvant treatment. We investigated new regimens to improve this type of chemotherapy and reached a remission rate of 93% with a combination of adriamycin and docetaxel (ADoc). A randomized study (GEPARDO-study) comparing ADoc with ADoc + tamoxifen has recently been started in Germany by the German Adjuvant Breast Cancer Study Group (GABG).

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1998

Spontaneous apoptosis in ovarian cancer: an unfavorable prognostic factor.

Apoptosis and cell proliferation play important roles in the cellular response to chemotherapy, and may have prognostic value. The percentage of apoptotic cells [apoptotic index (AI)] was evaluated in ovarian carcinomas of 25 patients by the terminal desoxynucleotidyl transferase-mediated dUTP-nick end labeling (TUNEL) technique. All patients were surgically treated and received postoperatively chemotherapy consisting of cytoxan and cisplatin or carboplatin. As a marker of proliferation the mRNA expression of histone H3 in tumor tissue was determined. In addition, tumor vascularity was assessed by immunohistochemistry and factor VIII. Patients with high AI had significantly shorter survival times (p=0. 0001) or recurrence-free intervals (p=0.004) than patients with low AI. No significant relationship was found between AI and histone H3 mRNA expression, however, an inverse correlation of AI with microvessel density was detected. Tumors with high AI had significantly lower microvessel count than tumors with low AI (p=0. 002). The obtained data suggest that AI can be predictive of treatment outcome in ovarian cancer.

Antineoplastic Agents↗
PubMed1998

Transforming growth factor-beta stimulates urokinase expression in tumor-associated macrophages of the breast.

Recent studies have shown that urokinase (uPA) is an independent prognostic marker in breast cancer. uPA plays a key role in the degradation of tumor matrix and promotes tumor progression. Macrophage expression of uPA appears to be important in this context. Our objective in the present study was to provide evidence that tumor growth factor-beta (TGF-beta) released from breast cancer cells markedly up-regulates uPA expression in tumor-associated macrophages (TAMs). TAMs from 32 breast carcinomas were cultured. Blood monocytes from healthy donors and breast cancer patients as well as tissue macrophages from patients with fibrocystic changes of the breast were also examined. After TGF-beta incubation, uPA levels were tested by ELISA, and uPA mRNA levels were determined by Northern blot analysis. TGF-beta receptor and uPA cell surface fluorescence intensities were determined by flow cytometry; TGF-beta receptors were determined by Western blot analysis. Protein kinase-C dependence was also examined, and immunohistochemical stainings for uPA and TGF-beta were performed. We have demonstrated that TGF-beta markedly up-regulates basal uPA expression (mRNA and protein) in TAMs but only modestly increases uPA production in blood monocytes and tissue macrophages. Exposure of macrophages to TGF-beta1 led to a rapid and sustained increase in uPA mRNA levels, which was independent of de novo protein synthesis and completely inhibited by actinomycin D. H7 markedly reduced the ability of TGF-beta to stimulate uPA expression. Likewise, okadaic acid potentiated the ability of TGF-beta to up-regulate macrophage uPA expression. We suggest that TAMs are more responsive to TGF-beta stimulation than are blood monocytes and tissue macrophages because of different TGF-beta receptor densities. TGF-beta stimulates transcription of the uPA gene, increases uPA-mRNA stability, and activates uPA expression via protein kinase-C-dependent mechanisms. The ability of TGF-beta to induce macrophage uPA expression may provide an indirect mechanism by which this growth factor stimulates angiogenesis. It may be, therefore, that TAMs promote tumor progression and tumor angiogenesis.

Breast Neoplasms↗
PubMed1997

Parathyroid hormone-related protein (PTHrP) inhibits proliferation of Chinese hamster ovary cells stably transfected with a PTH/PTHrP receptor cDNA.

The effect of parathyroid hormone-related protein (PTHrP) on proliferation was examined in Chinese hamster ovary (CHO) cells transfected with a PTH/PTHrP receptor encoding cDNA. Treatment with chicken PTHrP(1-36) (chPTHrP) lowered the cell number to 49 +/- 2% of untreated controls after 6 days with a half-maximal effect at 1 nM. The effect was mimicked by human (h) PTH(1-34), Br-cAMP and forskolin, but not by the receptor antagonist hPTH(3-34). Reduction of cell number was accompanied by increased PTH/PTHrP receptor expression and persistently activated adenylyl cyclase, together with altered cell morphology from epithelial to spindle-like forms, clustered growth and increased phosphate uptake. chPTHrP increased [Ca2+]i, but failed to activate membrane bound protein kinase C (PKC). Pretreatment with chPTHrP did not affect phorbol ester stimulated PKC activity, and chPTHrP or serum evoked increases in [Ca2+]i. In conclusion, PTHrP induced inhibition of proliferation and altered cell morphology is mediated by increased adenylyl cyclase rather than by PKC-dependent mechanisms in CHO cells.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1997

Unstable proteins: how to subject them to chromatographic separations for purification procedures.

The chromatographic separation of an unstable protein is often a challenge to the scientist working in the field of life sciences. Especially for the purification of sensitive enzymes, making use of conventional chromatographic techniques is difficult and frequently results in a complete loss of biological activity of the target protein. This report summarizes some general strategies that may help to keep unstable proteins in their native conformation during the rather harsh conditions of a purification procedure. In this context, a recently developed hollow fiber membrane module, suitable for performing on-line dialysis, is introduced and examples of its application to liquid column chromatography are given. Many innovative separation techniques, characterized by dramatic improvements in both performance and separation time, have recently been developed. Since the chromatographic separation of unstable proteins requires the use of modern state-of-the-art equipment and technology, emphasis is given to newly developed separation techniques such as expanded bed adsorption, perfusion chromatography, protein free flow electrophoresis and the use of tentacle gels. In addition, examples of recently published purifications of unstable proteins are discussed with respect to strategies ensuring the preservation of the native protein structure during chromatographic separation.

Adsorption↗
PubMed1997

Comparison of estrogen receptor DNA binding in untreated and acquired antiestrogen-resistant human breast tumors.

Preliminary studies have suggested that measuring the ability of immunoreactive 67-kDa estrogen receptor (ER) to bind DNA and form in vitro complexes with its cognate estrogen response element (ERE) might serve to identify breast tumors most likely to respond to antiestrogens like tamoxifen. Data from two different surveys of untreated primary breast tumors confirmed that only 67% (74 of 111) of ER-positive tumors express a receptor capable of forming ER-ERE complexes by gel-shift assay, with tumors of lower ER content having significantly reduced ER DNA-binding frequency (56%) relative to those of higher ER content (82%; P = 0.007). In contrast to these untreated tumors, a panel of 41 receptor-positive breast tumors excised after acquiring clinical resistance to tamoxifen during either primary (n = 26) or adjuvant therapy (n = 15) showed a significantly greater ER DNA-binding frequency, with nearly 90% capable of forming ER-ERE complexes (P < 0.02). To assess experimentally whether ER DNA-binding function is altered during the development of antiestrogen resistance, nude mouse MCF-7 tumor xenografts were analyzed before and after the acquisition of in vivo resistance to either tamoxifen or a pure steroidal antiestrogen, ICI 182,780. Tamoxifen-resistant MCF-7 tumors retained full expression of 67-kDa DNA-binding ER, and despite a markedly reduced ER content in the ICI 182,780-treated tumors, the expressed ER in these antiestrogen-resistant tumors exhibited full ability to form ER-ERE complexes. These findings indicate that breast tumors with acquired antiestrogen resistance continue to express ER of normal size and DNA-binding ability and suggest that the failure of antiestrogens to arrest tumor growth during emergence of clinical resistance results from an altered gene-regulatory mechanism(s) other than ER-ERE complex formation.

Animals↗
PubMed1997

Rapid analysis of distinctive CD44 RNA splicing preferences that characterize colonic tumors.

In normal tissues, the steady-state level of CD44 mRNA is low, and the variety of alternatively spliced transcripts produced by this complex gene is limited. Conversely, increased and disorderly expression of this gene has been observed in a number of types of cancer. This study analyzed the order in which the CD44 variant exons are spliced together in gastrointestinal tumor cell lines and in 20 colonic carcinomas and matched normal mucosa. We used a PCR-based assay to analyze specific exon junctions at the boundary of the standard and variant regions of the CD44 gene transcripts. This revealed characteristically different splicing preferences in colonic tumor and normal tissues. The junction of exon 5 to exon 8 appeared to be the most prevalent in normal mucosa, whereas the presence of junctions between exon 5 and either exon 7, 9, or 11 were increased markedly in tumor samples. These observations demonstrate that the unusual variety of CD44 transcripts in cancer cells results from the fidelity of alternative splicing mechanisms being compromised and are potentially useful as tumor cell markers in diagnostic assays.

Blotting, Southern↗
PubMed1997

Melanoma-inhibiting activity, a novel serum marker for progression of malignant melanoma.

Melanoma-inhibiting activity (MIA) was isolated previously as a small soluble protein secreted from malignant melanoma cell lines in vitro. In vivo, highly restricted expression patterns in melanocytic tumors were identified. We therefore quantitated serum levels of MIA protein by means of a nonradioactive ELISA and investigated whether MIA provides a clinically useful parameter in patients with malignant melanomas. Here, we report enhanced MIA serum levels in 13 and 23% of patients with stage I and II disease, respectively, and in 100% with stage III or IV disease. Compared with S-100 and soluble intercellular adhesion molecule 1 serum levels in these patients, MIA was the most sensitive marker. Response to therapy in stage IV disease correlated with changes in MIA serum levels. Measuring repeatedly sera of 350 patients with a history of stage I or II melanoma during follow-up, we detected 32 patients developing positive MIA values. At the time of serum analysis, 15 of them had developed metastases, and one presented with metastatic disease 6 months later. In contrast, none of the patients with normal MIA serum levels developed metastases during the follow-up period of 6-12 months. In conclusion, MIA represents a novel serum marker for systemic malignant melanoma revealing the highest sensitivity and specificity among currently available markers. Useful clinical applications include staging of primary melanomas, detection of progression from localized to metastatic disease during follow-up, and monitoring therapy of advanced melanomas.

Adult↗
PubMed1997

[Risk of hepatitis C virus infection in medical occupations].

Following the introduction of sensitive and specific tests for the detection of hepatitis C virus (HCV) infection studies could be performed to determine the risk to acquire a HCV infection in medical professions. The aim of this report is to summarize the knowledge in this field, especially regarding the risk of transmission of HC virus by injuries with infected material, such as needles. The risk to acquire a HCV infection following needlestick injuries was found to be markedly lower than the risk for transmission of hepatitis B virus infection. In 7 studies from different countries this risk has been found to be between zero to a maximum of 10% (average 2%). When the frequency of HCV infection was studied in occupational groups in hospital (nurses, technical assistants, doctors), it did not differ significantly compared to the prevalence in general population. These and other findings concerning the risk of transmission of HCV infections (between spouses, mother/newborns) clearly show that the risk of transmission of HCV infection is markedly lower than that of HBV infection. These facts should be considered in judging of applications for the recognition of HCV infection as occupational disease.

Adult↗
PubMed1997

Multifunctional tryptophan-synthesizing enzyme. The molecular weight of the Euglena gracilis protein is unexpectedly low.

After developing a suitable procedure to produce large amounts of Euglena gracilis as well as a reliable protocol to purify the multifunctional tryptophan-synthesizing enzyme derived from it (Schwarz, T., Bartholmes, P., and Kaufmann, M. (1995) Biotechnol. Appl. Biochem. 22, 179-190), we here describe structural and catalytic properties of the multifunctional tryptophan-synthesizing enzyme. The kinetic parameters kcat of all five activities and Km for the main substrates were determined. The relative molecular weight under denaturing conditions as judged by SDS-polyacrylamide gel electrophoresis is 136,000. Cross-linking as well as gel filtration experiments revealed that the enzyme exists as a homodimer. Neither intersubunit disulfide linkages nor glycosylations were detected. On the other hand, the polypeptide chains are blocked N-terminally. Complete tryptic digestion of the protomer, high pressure liquid chromatography separation of the resulting peptides, and N-terminal sequence analysis of homogenous peaks as judged by matrix-assisted laser/desorption ionization time-of-flight mass spectrometry was performed. Depending on the sequenced peptides, alignments to all entries of the SwissProt data base resulted in both strong sequence homologies to known Trp sequences and no similarities at all. Proteolytic digestion under native conditions using endoproteinase Glu-C uncovered one major cleavage site yielding a semistable, N-terminally blocked fragment with a molecular weight of 119,000. In addition, an increase in beta-elimination accompanied by a decrease in beta-replacement activity of the beta-reaction during proteolysis was observed.

Amino Acid Sequence↗
PubMed1997

Expression of CD44V2 in transitional cell carcinoma of the urinary bladder and in urine.

CD44 is the principal cell surface receptor for hyaluronate. Variant forms of the receptor, produced by alternative splicing, have been found to be associated with tumor progression in a variety of cancers. Based on investigations at the RNA level, it has recently been proposed that expression of CD44 variant V2 was present in urothelial cancer but not in normal urothelium. Since a distinctive marker for urothelial cancer would be extremely useful, frozen sections of normal urothelium and urothelial cancer were examined for expression of standard CD44 and CD44V2. Frozen sections of specimens of 35 patients with transitional cell carcinoma of the bladder, 16 specimens of normal bladder and 5 ureters were examined. Immunohistochemical staining was performed using a polyclonal antibody to CD44V2 (PAB CD44V2), a monoclonal antibody to CD44V2 (MAB CD44V2) and a monoclonal antibody to CD44S (MAB CD44S). CD44V2 and CD44S were also measured in lysates of urine sediments from 21 patients by enzyme-linked immunoabsorbent assay (ELISA). All investigated transitional cell carcinomas expressed CD44V2. There was no differentiation between invasive and noninvasive carcinoma. CD44V2 was also expressed in normal urothelium. Standard CD44 was expressed by the transitional cell carcinoma, normal urothelium, musculature and interstitial tissue. The amount of CD44V2 and CD44S in lysates of urine sediments is not correlated to diagnosis. In contrast to investigations at the RNA level, CD44V2 on the protein level seems not to be a distinctive marker for urothelial cancer. Therefore, CD44V2 will not be a useful diagnostic marker for detection of transitional cell carcinoma.

Antibody Specificity↗