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Biomedical subjects

C Marchal

Publications and source records attributed to C Marchal.

216 records · Page 12Linked to original sources
PubMedDate not supplied

Hyperthermia and cytotoxic drugs. Possible use of lanthanum as a potentiator of hyperthermia.

Recent studies indicate that differences in membrane fluidity may account for differences of thermal sensitivity. This possibility was studied by using lanthanum, a trivalent cation which is known to displace calcium in a number of biological systems, to modify the structural framework of cell membranes and consequently their biological properties. With Ehrlich ascites cells trypan blue exclusion uptake of 86Rb, 42K and 45Ca, indicate an increase of plasma cell permeability by La3+. The reduction of 86Rb and 42K uptake by tumour cells with La3+ appears to be independent of temperature. The increase of 45Ca2+ influx in the presence of lanthanum plus hyperthermia seems related to an important loss of cell viability. The enhancement of hyperthermia lethality by concentrations of lanthanum over 0.5 mM after 2 h at 44 degrees C has been demonstrated using HeLa S3 cells using a standard cloning technique. In vivo experiments have been performed on C3H mice bearing rhabdomyosarcoma using ultrasound heating at 44-46 degrees C. The results show a remarkable inhibition of tumour growth and a significant increase of the survival time after only one hyperthermia session of 30 min combined with one intratumoural injection of 1 mM lanthanum chloride.

Animals↗
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Practical interstitial method of heating operating at 27.12 MHz.

A practical interstitial capacitive method of heating using thin flexible coated electrodes operating at 27.12 MHz is described. Advantages compared to classical interstitial methods are: uniform heating, control of the inserted length, compatibility with curie therapy, simplicity and low cost. The electrode geometry could be designed according to tumour site and volume. Restriction of longitudinal heating to a part of the wire is also possible. A simple matching circuit can be connected to the active wires to obtain a standing wave ratio (SWR) of less than 1.5. Individual power regulation of the electrode should be used and is feasible at this frequency. Numerical, experimental and clinical results demonstrate the practical value of this method.

Animals↗
PubMedDate not supplied

Dielectric properties of gelatine phantoms used for simulations of biological tissues between 10 and 50 MHz.

The use of gelatine phantoms for simulating the dielectric properties of human tissues is suggested. These phantoms are mainly made of gelatine and water and are therefore readily prepared at a low cost. They can be poured into moulds and adopt various shapes depending on the organ to be simulated. In addition, their preservation is not critical. We have studied, at 10, 27 and 50 MHz, the variations of relative permittivity and conductivity as a function of temperature between 15 and 50 degrees C. What is shown is that those values vary both as a function of gelatine concentrations and as a function of temperature. For example, at 37 degrees C and 27 MHz, variations of relative permittivity from 87 to 100 and variations of the conductivity from 0.27 to 0.45 S/m for concentrations of 10% to 40% are observed. At the above frequency, the permittivity of human and animal tissues range between 95 and 180 and the conductivity between 0.4 and 0.6 S/m. Furthermore, the addition of sodium chloride at variable concentrations enables both conductivity and permittivity values to be modified. We propose, as 'muscle-equivalent' phantoms at 27 MHz, a phantom consisting of 20% gelatine with an electrical conductivity from 0.27 to 0.48 S/m and a relative permittivity from 90 to 93 at temperatures between 15 and 50 degrees C. These gelatine, water and sodium chloride phantoms are adapted for easy and cheap simulation of most human tissues in a temperature range from 15 to 50 degrees C, for frequencies from 10 to 50 MHz.

Electric Conductivity↗
PubMedDate not supplied

Breast carcinoma located in ectopic breast tissue: a case report and review of the literature.

Ectopic breast tissue usually develops along the mammary ridge. The incidence of this anomaly has been reported as high as 6%. Malignant development is rare. A case of carcinoma of aberrant breast tissue, located in the axilla is described. Mammographies of the ectopic breast performed few years before the diagnosis of carcinoma are presented and also those done for the diagnosis of the tumor. A literature study was performed on carcinoma and ectopic breast tissue. Considering high frequence of node involvements for these cases, the optimal therapeutic strategies are discussed.

Antineoplastic Combined Chemotherapy Protocols↗
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[Updating 1999 of Standards, Options and Recommendations (SOR) for the clinical use of erythropoietin in oncology. FEDERATION OF THE FRENCH CANCER CENTRES (FNCLCC)].

CONTEXT: The < > (SOR), started in 1993, are a collaborative project between the Federation of the French Cancer Centres (FNCLCC), the 20 French Cancer Centres and specialists from French Public Universities, General Hospitals and Private Clinics. The main objective is the development of clinical practice guidelines to improve the quality of health care and outcomes for cancer patients. The methodology is based on literature review and critical appraisal by a multidisciplinary experts group, with feedback from specialists in cancer care delivery. The initial guidelines are being updated in case of new evidence. OBJECTIVES: To update the clinical practice guideline [39] with definitions of new Standards, Options and Recommendations for the use of recombinant human erythropoietin (rHuEPO) in oncology. METHODS: Data have been identified by literature search using Medline, Current Contents, Embase, Cancerlit (march 1996-march 1999). The main end points considered were hemoglobin level, haematocrit, quality of life, transfusion requirements, incidence and length of hospital stays, efficacy of cancer treatment, safety and costs. Once the guideline was updated and defined, the document was submitted to 42 reviewers for peer review, and to the medical committees of the 20 French Cancer Centres for review and agreement. RESULTS: The new key recommendations are: 1) The use of recombinant human erythropoietin in oncology is an alternative to treat chemotherapy-induced anemia when the chemotherapeutic regimen contains platinum; 2) Cancer-induced anemia reduces patients' quality of life. Treatment of anemia by transfusions of erythropoietin may improve quality of life; 3) We recommend assessment of haemoglobin levels during radiation therapy and the possible use of erythropoietin to optimise the efficacy of radiation therapy; 4) Erythropoietin is effective in others pathologies (multiple myeloma, non-Hodgkin lymphoma, non-platinum based chemotherapy.) and also in pediatric patients but the risk/benefit ratio for anemia therapy (i.e. transfusion or erythropoietin therapy) must be analysed for each individual; 5) We recommend an economic analysis of the need of erythropoietin within the context of the french health care system.

Anemia↗
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Determination of estrogen and progesterone receptors in endometrial adenocarcinomas. Comparison between dextran-coated charcoal and immunoenzymatic methods on curettage biopsies.

Estrogen receptors (ER) and progesterone receptors (PR) were determined on curettages from women with endometrial adenocarcinoma. The results obtained with the enzyme immunoassay (EIA) and the dextran-coated charcoal (DCC) assay were compared. A highly significant correlation was obtained between these methods for the ER measurement (Rs = 0.91). For PR determination, the Rs value between EIA and DCC assay was 0.57 and the mean value of PR-DCC is significantly higher than the mean value of PR-EIA. These results suggest that EIA is a suitable method for ER measurement. For PR determination on curettage material the DCC assay seems more accurate than EIA.

Adenocarcinoma↗
PubMedDate not supplied

[Molecular bases of virulence in Neisseria gonorrhoeae].

Gonorrhea remains of clinical concern, due to its frequency, complications, sequelae, increasing prevalence of antibiotic-resistant strains and absence of vaccine. A better understanding of the first stages of infection as well as of mechanisms of escape to immune response appears important. Many pathogenic bacteria express pili on their all surfaces. These structures mediate binding of bacteria to host tissues. Furthermore, gonococcal pili are submitted to a high rate antigenic variation, allowing the escape to host immune response. Pilin antigenic variation occurs by DNA recombination between one of the silent partial variant gene segments and an expressed pilin genes. We have shown that transformation of living bacteria by DNA liberated from lysed cells is a critical strep for antigenic variation. This constitutes the first specific function for a DNA transformation system. Piliation and virulence can change with culture conditions. This observation suggests that pilin expression would be subjected to an adaptative response. We have identified and characterized two genes which act in trans to regulate pilus expression. They determine synthesis of a response regulator and a membrane located sensor. They appear to regulate expression of other genes, possibly also involved in virulence. We present evidence for several environmental factors which may control the degree of piliation.

Antigenic Variation↗
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Sensitivity to taxoid derivatives of a newly established human endometrioid ovarian adenocarcinoma radioresistant cell line.

An endometrioid ovarian adenocarcinoma cell line CAVEOC-2 was characterized. Maintained in monolayered culture, CAVEOC-2 cells exhibited a 33-hr doubling time. When xenografted into nude mice, these cells produced fast growing tumors. Colony-forming efficiency in agar was 50%. DNA index was 1.5 and cytogenetic analysis showed a triploid karyotype. CAVEOC-2 cells did not express mdr-1 gene and were chemosensitive to doxorubicin (IC50 = 1.82 +/- 0.76 mumol/l), paclitaxel (IC50 = 3.33 +/- 0.26 nmol/l) and docetaxel (IC50 = 0.68 +/- 0.28 nmol/l), while they showed an intermediate sensitivity to cisplatin (IC50 = 9.40 +/- 1.02 mumol/l). CAVEOC-2 cells seemed highly radioresistant (SF2 = 0.81, alpha = 0.02 Gy-1, beta = 0.025 Gy2, and MID = 4.31 Gy). Activities of glutathione S transferase and gamma-glutamyl transpeptidase were respectively 23.5- and 3.4- fold higher than those of sensitive A2780 cell line. These characteristics make the CAVEOC-2 cells a suitable model for the study of human endometrioid ovarian adenocarcinoma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
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Deletion of 11 amino acids in tuberin associated with severe tuberous sclerosis phenotypes: evidence for a new essential domain in the first third of the protein.

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder displaying a large spectrum of symptoms. Linkage studies have shown two loci, TSC1 in 9q34 and TSC2 in 16p13.3, to be involved in the disease. The TSC2 gene, composed of 41 exons, has been isolated and is shown to encode a protein, tuberin, from a 5.5-kb transcript. Mutation screening for both clinical diagnosis and identification of functional domains within the tuberin is in progress. In this study we identify a 33-bp in-frame deletion (1462del33) in the mRNA which segregates in two unrelated French families with severe TSC phenotypes. The corresponding 11 amino acids deletion (aa 482-492) is shown to result from two different splice site mutations at exon 14 and, when compared with the position of two previously described missense mutations, indicates a novel functionally important region of the protein.

Amino Acid Sequence↗