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Biomedical subjects

J Michel

Publications and source records attributed to J Michel.

At least 91 records · Page 5Linked to original sources
PubMed1995

Computerized dynamic electrocardio-respirography with psychic load: new possibilities for preventive health care.

Proceeding from the role played by psychic load as a pathogenetic factor, its mechanism of action and its predominant importance in every-day life, a computerized system-analytical method was developed by which regulatory disorders may be realized under close-to-reality psychic load as possible risk factors or precursors of organically manifest illness. The method has already been introduced for routine preventive diagnostics under the heading of dynamic electrocardiography with standardized psychic load since cardiac arrhythmia, due to psychic load, has proved to be of particular relevance to preventive health care. The conditions for preventive health care and for further elucidation of psychophysiological regulation behavior have been substantially improved by its recent expansion to the level of dynamic electrocardio-respirography which additionally enables differentiated regulation-diagnostic evaluation of the respiratory system and its close interrelations with the cardiovascular system.

Adult↗
PubMed1994

Reduction of DNA synthesis, pigment synthesis, pigmentation gene mRNA and resistance to UVB in human melanoma cells treated with analogues of a histamine (H2) agonist.

Two groups of S-[2-(N,N-dialkylamino)ethyl]isothiourea derivates which depigmented melanoma cells either with inhibition of tyrosinase (group 1, R = methyl, isopropyl) or without inhibition of tyrosinase (group 2, R = benzyl, phenyl) were studied. Treatment of human melanoma cells with non-lethal doses of group 1 drugs led to a reduction in the levels of mRNA for the pigmentation genes tyrosinase, tyrosinase-related protein-1 and Pmel 17. The group 1 drug S-[2-N,N-diisopropylamino)ethyl[isothiourea] (DINOR) (R = isopropyl) produced only moderate inhibition of DNA, RNA and protein synthesis in three cell lines during the first 24 hr of treatment, and there was no correlation between the extent of inhibition and long-term toxicity. A group 2 drug (R = benzyl) rapidly inhibited DNA synthesis in an amelanotic melanoma cell line (MM96E) sensitive to killing by the drug; association of the latter with inhibition of RNA or protein synthesis was less clear. MM96E cells were also sensitive to killing by reactive oxygen species. In pigmented melanoma cells (MM418), incorporation of [125I]thiouracil, a false precursor of melanin, increased during the first 24 hr of treatment with DINOR whereas a group 2 drug (R = phenyl) inhibited incorporation of [125I]thiouracil. Cells depigmented by treatment with drugs from either group suffered the same amount of DNA damage as pigmented cells after UVB irradiation, as judged by inhibition of DNA synthesis, but did not recover as well as pigmented cells, whether or not drug was present during recovery. The results suggested that (1) group 1 agents down-regulated message for several pigmentation genes, possibly at the transcriptional level; (2) the toxicity of group 2 drugs was related to reactive oxygen species; and (3) melanin protected cells from UVB by enhancing cellular recovery.

Blotting, Northern↗
PubMed1994

Transcriptional regulation of differentiation, selective toxicity and ATGCAAAT binding of bisbenzimidazole derivatives in human melanoma cells.

To study the relationship between the structure of minor groove ligands and their affinity for specific DNA sequences that regulate gene transcription, three analogues of the A-T-specific DNA minor groove ligands Hoechst 33258 and Hoechst 33342 were synthesized with 5, 8 or 12 carbons in an aliphatic chain attached to the phenolic oxygen of the molecule. There was a striking bimodal relationship between toxicity to HeLa cells and the lipophilicity of the five analogues, toxicity being low for the compounds with a free hydroxyl (Hoechst 33258) or a 12-carbon substituent, yet high for the 5-carbon analogue. Selective killing of human melanoma cells compared with normal fibroblasts was observed for the Hoechst analogue with a 12-carbon chain attached. Hoechst 33258 itself was selectively toxic for the MM96E melanoma cell line compared with other cell lines, induced a highly dendritic morphology, increased tyrosinase activity and tyrosinase mRNA but decreased the level of gp75 (TRP-1) mRNA; message for a third pigment gene, Pmel-17, was unchanged. Tyrosinase activity was decreased in the resistant A2058 melanoma cell line and transcription was affected to a lesser extent than in MM96E. Expression of gp75 protein and two intermediate filament proteins was inhibited by Hoechst 33258 in MM96E cells. There was no major difference in the amount of 125I-Hoechst 33258 taken up by sensitive and resistant cells. Of the five derivatives studied, the parent drug Hoechst 33258 and the 2-carbon analogue (Hoechst 33342) were found to have the most inhibitory effect on affinity of octamer binding proteins for the ATGCAAAT consensus sequence found in the promoter region of certain genes associated with proliferation and differentiation. In contrast to Distamycin A (also an A-T-specific minor groove ligand), Hoechst 33258 displaced proteins already bound to the octamer motif. The G-C ligand chromomycin A3 exhibited a different spectrum of cell toxicity and tyrosinase stimulation compared with Hoechst 33258. Chromomycin A3 but not Hoechst 33258, strongly inhibited the zinc-dependent transcriptional activity of the sheep metallothionein-Ia promoter in reporter gene assays of transfected cells. Since the six metal-responsive elements of the promoter are GC-rich, this provides independent evidence for the sequence-specificity of transcriptional inactivation by one of these drugs in melanoma cells. Overall, the results suggest that Hoechst 33258 acts by inhibiting the transcription of specific genes, cell lines evidently differing in the accessibility to drugs of certain A-T-rich sequences.

Base Sequence↗
PubMed1994

Long-term survival after chemotherapy containing platinum derivatives in patients with advanced unresectable non-small cell lung cancer. European Lung Cancer Working Party.

The study set out to determine the rate of long-term survivors (LTS) in patients treated with platinum-containing chemotherapy for advanced non-small cell lung cancer (NSCLC), to identify prognostic factors predicting long-term survival (> or = 2 years) and to report the LTS natural history. Eligible patients with advanced NSCLC treated by chemotherapy in one of seven trials conducted by the European Lung Cancer Working Party from December 1980 to August 1991 were included. All patients received cisplatin and/or carboplatin. Of these, 1052 patients were eligible and 24 variables were analysed as potential prognostic factors. Actuarial 2-year and 5-year survival rates were, respectively, 7.4 and 1.8%. All patients surviving for > or = 5 years had limited disease and were treated by complementary chest irradiation and/or surgery. Univariate prognostic factor analysis for LTS identified as significant no major weight loss, limited disease, no liver metastases, normal white blood cells and neutrophils and normal lactic dehydrogenase levels. By multivariate analysis, the only significant factor was limited disease. Objective response to chemotherapy was also found to be, as disease extent, a highly significant predictor for LTS. Thus, the two best prognostic factors for LTS were non-metastatic disease and response to chemotherapy.

Aged↗
PubMed1994

Dose-finding study of tropisetron in cisplatin-induced nausea and vomiting.

BACKGROUND: The purpose of these two studies was to define the optimal therapeutic dose of the 5-HT3 receptor antagonist tropisetron (Navoban, ICS 205-930) in cisplatin-induced nausea and vomiting. PATIENTS AND METHODS: In two multicentre, dose-finding studies of tropisetron in the prevention of cisplatin-induced emesis, cancer patients naïve to chemotherapy or who had not vomited previously were randomly assigned to tropisetron 5, 10, 20 or 40 mg (study I, 143 patients) or 2 or 5 mg (study II, 74 patients), administered as a single intravenous dose over 15 minutes just before the start of chemotherapy. RESULTS: In study I total control of acute symptoms (no nausea and no vomiting) was achieved in, respectively, 66%, 50%, 64% and 50% in the 5-, 10-, 20- and 40-mg groups of patients. A total absence of vomiting alone was seen in, respectively, 71%, 51%, 61% or 58% of patients. None of the differences were statistically significant. In study II there was total acute control in 57% of patients in the 2-mg group and 63% in the 5-mg group (p = NS). Total or major control of vomiting (< or = 2 emetic episodes) was the primary endpoint in study II and was seen in 68% of patients for the 2-mg and 86% for the 5-mg group (p = 0.055). In this study failures ( > 3 vomiting) were rescued with a second infusion of tropisetron (5-mg fixed dose). Three of 8 rescue infusions administered in the 2-mg group prevented further vomiting whereas none of 5 were successful in the 5-mg group during course 1 of chemotherapy. The most frequently reported adverse effects (over all three courses) were headache (6.0% of 217 patients) hypertension (3.7%) and diarrhoea (2.8%). None of the 25 deaths which occurred during the two studies were attributable to tropisetron. CONCLUSIONS: Thus, a single dose of tropisetron provides 24-hour protection against cisplatin-induced nausea and vomiting and is well tolerated. These studies do not allow a firm conclusion but suggest that 2 mg may be subtherapeutic and that 5 mg is as effective as higher doses.

Adult↗
PubMed1994

[Small cell bronchial cancer. Comparison of results of weekly polychemotherapy using multiple drugs with standard chemotherapy. European Lung Cancer Working Party].

The administration of multiple cytostatic drugs on a weekly basis has been proposed as a new intensive chemotherapy modality for small-cell lung cancer. The European Lung Cancer Working Party has conducted a randomized trial comparing to a standard regimen (cyclophosphamide + adriamycin + etoposide given at the cycle beginning) a weekly chemotherapy with 7 active drugs (cyclophosphamide + adriamycin + etoposide on day 1; cisplatin + vindesine on day 8; methotrexate + vincristine on day 15). A total of 215 eligible patients have been registered. There has been no significant difference between the 2 arms for response and for survival. The total relative dose-intensity has been lower in the weekly chemotherapy arm. This approach has failed to improve current results.

Adult↗
PubMed1993

Subcellular calcium localization in Toxoplasma gondii by electron microscopy and by X-ray and electron energy loss spectroscopies.

The localization of calcium in Toxoplasma gondii tachyzoites was studied at the ultrastructural level, with a cytochemical pyroantimonate precipitation method (PA) and controlled by EGTA chelating and EDX and EELS microanalyses. Appropriate conditions for material preparation, fixation and embedding, were defined. The proportion of precipitates that were either free or inside vacuoles and their distribution inside Toxoplasma appeared to be PA dose-dependent. Precipitation mainly occurred in the anterior pole of the Epon-embedded tachyzoites. EDX and EELS analyses showed that out of 30 PA precipitates inside tachyzoites, 78% contained Ca. In Melamine sections, 96% of the tachyzoites had intracellular precipitates and the membrane complex was stained; 25% of the tachyzoites inside host cells contained PA-Ca precipitates, but most of them were retained in the reticular network of the parasitophorous vacuole. Melamine embedding appeared to improve the preservation of calcium pyroantimonate precipitates.

Animals↗
PubMed1993

Multiple-drug weekly chemotherapy versus standard combination regimen in small-cell lung cancer: a phase III randomized study conducted by the European Lung Cancer Working Party.

PURPOSE: A randomized trial was conducted in patients with small-cell lung cancer (SCLC) to determine if survival can be improved by a weekly chemotherapy regimen combining various drugs. PATIENTS AND METHODS: Two hundred twenty-three patients were randomized to receive either six courses of a multiple-drug combination (MDC) regimen (Adriamycin [ADR; doxorubicin; Farmitalia Carlo Erba, Milan, Italy] 25 mg/m2 intravenously [i.v.] on day 1; etoposide [VP16] 120 mg/m2 i.v. on day 1; cyclophosphamide [CPA] 500 mg/m2 i.v. on day 1; cisplatin 60 mg/m2 i.v. on day 8; vindesine [VDS] 3 mg/m2 i.v. on day 8; vincristine [VCR] 2 mg i.v. on day 15; methotrexate [MTX] 100 mg/m2 i.v. on day 15), or a standard chemotherapy (SC) regimen (ADR 50 mg/m2 i.v. on day 1; CPA 1 g/m2 i.v. on day 1; VP16 80 mg/m2 i.v. on days 1 to 3). RESULTS: In 98 MDC-treated and 101 SC-treated assessable patients, we observed 69% and 62% objective responses rates, respectively. There was no significant difference in survival, with median durations and 2-year overall survival rates of 49 and 43 weeks and 8.5% and 7.9%, respectively. There was a significant increase in response rate in favor of MDC patients with limited disease (84% v 62%). Toxicity was tolerable, although SC was more hematotoxic, with 76% (v 59%) experiencing leukopenia and 17% (v 7%) experiencing thrombocytopenia (grades III and IV). If the cumulative doses received were nearly equal to the scheduled cumulative doses in both arms, the total relative dose-intensity (RDI) was significantly higher in the SC arm. The difference was due to increased treatment delays in the MDC arm. CONCLUSION: Weekly MDC failed to improve survival rates in patients with SCLC.

Adult↗
PubMed1993

Effect of age and duration of disease on the clinical manifestations of brucellosis. A study of 73 consecutive patients in Israel.

We describe our experience with 73 patients diagnosed with brucellosis during the years 1979-91 at two Jerusalem hospitals: Hadassah Mount Scopus (37 patients from 1979-1984) and Shaare Zedek (36 patients from 1979-1991). The patients included 32 children less than 14 years old and 41 adults; 70 of the patients were non-Jews. In all cases the pathogen was Brucella melitensis. The high proportion of children and the equal sex distribution was quite different from the age and sex distribution of brucellosis in Western countries where it is more common in adult males, and similar to that reported from other near-Eastern countries where household dairy products, and not occupational exposure, are the most common source of infection. The short duration of disease (< 2 weeks) prior to diagnosis in 70% of the patients is attributed to the ready availability of appropriate medical care, and a very high index of suspicion for brucellosis in the Jerusalem non-Jewish population. Abdominal symptoms were more common in adults, whereas enlarged lymph nodes and liver, skin rash and pharyngitis were more frequently observed in children. Some of these differences may be attributed to the very short duration of disease in most children at the time of presentation. Combination therapy with tetracycline-streptomycin or tetracycline-rifampin yielded superior results as compared with single-drug treatment in terms of early defervescence and relapse rates. The present experience underlines the importance of endemic brucellosis which still represents a significant public health problem in children and adults in Mediterranean countries.

Adolescent↗
PubMed1992

Courvoisier's sign revisited: two patients with palpable gallbladder.

More than a century ago, Courvoisier published his observation on the significance of a palpable gallbladder in the differential diagnosis of obstructive jaundice. We have described two patients with newly described conditions--AIDS-associated cholangiopathy and diet-induced cholecystitis--who had a palpable gallbladder and have discussed possible pathogenetic mechanisms.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Characterization of substance P-like immunoreactivity and tachykinin-encoding mRNAs in rat medullary thyroid carcinoma cell lines.

Rat thyroid tissue and three rat medullary thyroid carcinoma cell lines, 6-23, WE4/2, and CA77, have been examined for substance P (SP) and SP-like peptide expression. Analysis by combined HPLC and radioimmunoassay revealed the presence of SP in thyroid and 6-23 cell extracts. The presence of SP-encoding mRNAs was also detected in 6-23 cells by solution hybridization-nuclease protection analysis. SP-encoding mRNA expression was increased (fourfold) by maintaining the 6-23 cells in low serum (2%) for 4 or 10 days. The 6-23 cells also expressed other SP-like immunoreactive species, which were chromatographically and immunologically distinct from established tachykinin peptides. WE4/2 cells did not contain SP but did display SP-like immunoreactivity (SPLI), which migrated like the unidentified SPLI in 6-23 cells. CA77 cells did not contain SP or SP-encoding mRNA but did contain SPLI that migrated identically to the unidentified SPLI in the other cell lines. This novel SPLI was detected with an antiserum directed against the SP carboxyl terminus and to a lesser extent with an antiserum directed against the neurokinin A carboxyl terminus, but it showed minimal cross-reactivity using an antiserum directed against the midportion of SP. Treatment with 50 mM KCl resulted in secretion of this SPLI from CA77 cells. Gel filtration analysis demonstrated that this novel SPLI had an apparent molecular weight of approximately 1,000. These results are discussed in terms of cell lines that express tachykinin peptides and in terms of the molecular nature of the new SPLI detected in CA77 cells.

Animals↗
PubMed1992

Frequent loss of heterozygosity on chromosome 18 in ovarian adenocarcinoma which does not always include the DCC locus.

Inactivation of the DCC gene on chromosome 18 owing to loss of heterozygosity is a common finding in colorectal cancer. Because both ovarian and colon cancer are features of Lynch syndrome II, which has been provisionally mapped to chromosome 18, we hypothesized that loss of heterozygosity at the DCC locus may also occur in ovarian neoplasia. Fifty-two sporadic ovarian adenocarcinoma tumours were analysed by Southern blotting for loss of heterozygosity (LOH) at six chromosome 18 loci. Overall, tumours from 31 patients (60%) showed allelic loss at one or more of these loci. A similarly high level of LOH, 66%, was found at D17S5 (17p13.3). In contrast, moderate levels of LOH, of 31%, 39% and 33%, were found at MYCL1 (1p32), D1S57 (1p) and D14S20 (14q32.33) respectively. However, analysis of partial chromosome deletions in 11 patients indicates that the smallest region of overlap appears to exclude the DCC gene but to be between the D18S5 and D18S11 loci. This suggests that another locus, as well as or apart from DCC, may be involved.

Adenocarcinoma↗
PubMed1991

Intraoperative valvuloplasty in calcific aortic stenosis: a study comparing the mechanism of a novel expandable device with conventional balloon dilatation.

In selected patients with calcific aortic stenosis, balloon valvuloplasty is an intermediate alternative to surgery. The effect of balloon valvuloplasty to increase valve area, however, is limited and the restenosis rate is high during follow-up. To improve the results and reduce the complication rate, a new device for valvuloplasty of calcific aortic stenosis was developed. This system consists of three expandable prongs mounted on a freely movable catheter tip. To evaluate the efficacy of this new device, valvuloplasty was performed in 10 patients with severe aortic stenosis intraoperatively just prior to valve replacement. Comparison was made with the results of conventional balloon dilatation performed in an additional 20 patients during surgery. Using the new device, the relative orifice area increased from 10 +/- 3% before to 20 +/- 6% following intervention. However, in only one patient was a considerable increase of static valve area (greater than 15%) found. The results were comparable to the effect of conventional balloon dilatation, which led to an increase of orifice area from 12 +/- 7% to 24 +/- 10%. With both systems, the best results were achieved in patients with aortic stenosis and significant commissural fusion. In contrast, in bicuspid or tricuspid valves without fused commissures the effect of the intervention was limited. Because complete obstruction of the aortic valve does not occur during dilatation, this new device might be superior to conventional balloon dilatation. Preselection of patients according to the morphology of the valve seems mandatory to improve the success and reduce the complication rate of valvuloplasty in aortic stenosis.

Aged↗
PubMed1990

Experience of the Belgian Society of Medical Oncology with single-administration 5 g/m2 ifosfamide with mesna as second- or third-line therapy in advanced breast cancer.

In an ongoing phase II trial conducted in advanced breast cancer, we tested a therapy schedule consisting of continuous, 24-h infusion of 5 g/m2 ifosfamide (IFO) in 3 1 dextrose saline with mesna (MSN), repeated every 3 weeks until disease progression. Since September 1988, 16 heavily pretreated patients with advanced disease (11 with visceral lesions) considered refractory to standard chemotherapy (regimens always including cyclophosphamide) have been included. Objective partial remissions were observed in two cases (one in liver and one in soft-tissue and pleural lesions), and disease stabilization for at least 3 months occurred in four cases. No treatment-related death was recorded and tolerance was judged to be excellent (six cases) or acceptable in all instances. The haematological toxicity consisted mainly of transient leucopenia (nadirs evaluated by WHO scale as grade 3 in 43% and grade 4 in 29%), sometimes associated with thrombocytopenia (grade 3 in 7% and grade 4 in 7%). Other side effects included nausea and/or vomiting (grade 3-4 in 33%); worsening of preexisting alopecia (five cases); haemorrhagic cystitis (one case); mild, transient somnolence (two cases); and moderate fluid retention (two cases). We concluded that infusion of 5 g/m2 IFO over 24 h with MSN rescue might represent an acceptable second- or third-line salvage regimen. Close monitoring of haematological and renal function parameters is recommended. A larger number of patients will be treated in a continuation of this study to evaluate the true response rate within narrower confidence limits.

Adult↗