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Biomedical subjects

L Israël

Publications and source records attributed to L Israël.

At least 19 recordsLinked to original sources
PubMed1998

[Malignant progression and resistance of cancer cells: an inducible survival program similar to the SOS system of unicellular organisms induced by environmental assaults].

The hypothesis discussed in this paper states that defence and survival strategies of cancer cells against therapeutic approaches are similar in their mechanisms and homologous in several genes to the SOS program known in bacteria and induced by several assaults. The almost ineluctable malignant progression and its acceleration in response to various therapies should then be considered as an inducible system inherited from prokaryotes and repressed in multicellular organisms through the anti-oncogene system. The later, weakened in case of some inherited mutations yields even in sporadic cases to repeated assaults and to the decrease with time of internal defences, including antioxidant mechanisms. This theory which presents in a new perspective the biological status of cancer in the frame of Darwinian evolution and hence the strategies able to control its progression, leads itself to some predictions and testable assertions: absence of any anti-oncogene homologues in unicellular organisms, built-in weaknesses in anti-oncogenes, existence of a common repressor and a common derepressor mechanism for several distinct genes involved in cancer and in response to an environmental assault, and finally a possible transfer of drug resistance genes in malignant cells as it is the case for bacteria submitted to stress conditions.

Bacteria↗
PubMed1997

[Combined therapies in family practice and hospitals. A controlled clinical study of a population of 162 patients with criteria of age-related memory disorders].

OBJECTIVES: To assess the combination of drug and cognitive therapy on age-associated memory impairment (AAMI). PATIENTS AND METHODS: A double-blind randomized trial was performed involving 162 patients with age-associated memory impairment selected and followed by their general practitioners. Two intervention methods-a drug and a cognitive therapy-were assessed in combination. Three randomized parallel groups of 54 patients each, aged 55 years and over, were followed and treated for 3 months. After a placebo washout period of 10 days, one group received 2.4 g of piracetam, another group, 4.8 g and the third, a placebo. RESULTS: A total of 135 patients, 45 in each group, completed the study. Combined therapy was most effective in patients whose baseline performance on memory tests was lowest. The best results were observed with piracetam combined with memory training. This result confirmed by the global impression of the principal investigator was in agreement with findings of previous double-blind placebo-controlled trials assessing the combined effect of drug treatment and memory training. CONCLUSION: This result confirmed by the global impression of the principal investigator was in agreement with findings of previous double-blind placebo-controlled trials assessing the combined effect of drug treatment and memory training.

Aged↗
PubMed1996

Temporary ex vivo inhibition of the expression of the human oncogene HER2 (NEU) by a triple helix-forming oligonucleotide.

A 28-base phosphodiester triple helix-forming oligonucleotide, mostly G and A containing, targeted to a polypurine tract interrupted by a purine-pyrimidine inversion, situated upstream from the TATA box of the promoter of the human HER2 gene, was conceived by computer modeling. The "energetically best choice" was oligo 28(C), which formed the triple helix in vitro, as proved by gel retardation and Fourier transform infrared spectroscopy. When administered as a complex with lipofectin, fluorescence confocal microscopy and electrophoresis confirmed the delivery and persistence of this unprotected oligonucleotide inside MCF7 (breast cancer) cells. At a concentration of 2 microM, the oligonucleotide reduced within 6 h the HER2 mRNA level to 42% (Northern blot) but did not interfere with the transcription of a housekeeping gene, glyceraldehyde-3-phosphate dehydrogenase. During the first day of administration at 0.22 microM, it lowered to 59% the HER2 protein in treated, as compared to nontreated, cells (ELISA). The effect was sequence specific when compared to that of five different negative controls, and it was target selective when compared to the expression of a related, nontargeted protein, the epidermal growth factor receptor. By day 2, the inhibitory effect was overcome by replenishment reactions.

Base Sequence↗
PubMed1995

Sodium phenylacetate induces growth inhibition and Bcl-2 down-regulation and apoptosis in MCF7ras cells in vitro and in nude mice.

Using a highly tumorigenic human breast cancer model (Ha-ras-transfected MCF7 cell line) we analyzed the efficacy of the differentiation-inducing agent sodium phenylacetate (NaPA), both in vitro and in vivo. NaPA-treated MCF7ras cells showed dose-dependent growth inhibition from 2.5 to 15 mM without apparent toxicity. Western blot analysis showed a Bcl-2 down-regulation after 48 h treatment with 5 mM NaPA, together with apparition of apoptotic nuclei by DAPI staining. Mice bearing MCF7ras xenografts (n = 40) were treated for 2 weeks through s.c.-delivering osmotic pumps, followed by 6 weeks of daily i.p. NaPA administration. After 3 weeks, the treated tumors showed growth arrest without regression for the whole observation time, e.g., 12 weeks. Immunohistochemical analysis showed Bcl-2 down-regulation and differentiation patterns: decrease of Ki-67 and increase of steroid receptors (estrogen and progesterone receptors) compared to controls. Cells cultured from treated tumors (II.b) displayed pseudotrabecular disposition as MCF7ras cells treated in vitro. They also showed a higher NaPA sensitivity, together with 70% Bcl-2 down-regulation as compared to the derived cells of untreated tumors (II.a). When reinjected into nude mice, II.b cells induced only one poorly vascularized, noninvasive tumor (8%) with lower proliferation index, 100% progesterone receptor positive cells, and 35% terminal deoxynucleotidyltransferase-mediated dUTP-X nick end labeling (+) nuclei, as compared to 100% induction of highly vascularized and invasive tumors with 3% terminal deoxynucleotidyltransferase-mediated dUTP-X nick end labeling (+) nuclei induced by II.a cells.

Animals↗
PubMed1995

Evidence for separate mechanisms of antiproliferative action of indomethacin and prostaglandin on MCF-7 breast cancer cells.

Indomethacin is reported to decrease the growth of many tumour cell lines. It is also known to be an anti-inflammatory agent acting by the inhibition of prostaglandin (PG) synthesis. To evaluate a clinical application as antitumoral agent, we have studied whether antiproliferative effect of indomethacin in breast cancer is related to its action on the prostaglandin production. We have observed that indomethacin as well as PGE1, PGE2, PGD2, and PGI2 inhibited the proliferation of MCF-7 breast cancer cells. As breast carcinomas were described to secrete mainly PGE2, we studied the effect of PGE2 on MCF-7 cells. These cells contain two types of binding sites for PGE2: high-affinity (Kd = 0.2 nM) and low-affinity (Kd = 20 nM) receptors. In this cell line, indomethacin and PGE2 inhibitory effects were additive. In addition, we showed that PGE2 increased the cAMP level in MCF-7 cells 30-fold (p < 0.001) while indomethacin did not change basal cAMP accumulation. Like for combination PGE2/indomethacin, the inhibitory effects of a cAMP analog (8-Br-cAMP) and indomethacin were additive. In conclusion, indomethacin inhibits the MCF-7 growth in specific manner independently of PG synthesis, PG action and cAMP accumulation.

Analysis of Variance↗
PubMed1995

Alteration of prostaglandin E receptors in advanced breast tumour cell lines.

We studied the direct effects of PGE2, often produced at high levels by mammary tumours, on three human breast cancer cell lines diversely advanced in malignancy regarding differentiation and tumorigenicity in nude mice. We evaluated PGE2 effect on cell growth, PGE2 receptor level and functionality. Our results show that PGE2 induces cAMP accumulation and inhibits the growth of the most differentiated breast cancer cells. We also demonstrate that loss and probably dysfunction of PGE2 receptors is related to an advanced tumorigenic phenotype of the cells. Thus, it seems that during progression of breast cancer, the cell growth escapes from control by PGE2. Nevertheless, it is possible to control the growth of advanced breast cancer cells in vitro by direct induction of intracellular cAMP accumulation.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1993

[Infectious complications during treatments with interleukin-2].

Between January 1989 and May 1991, 97 patients were treated with interleukin 2 in the Oncology Department of the Avicenne Hospital (Bobigny, France). IL 2 was given over 5 days by continuous infusion through an implantable port. Ten patients (4 males, 6 females), mean age 46 years (36-67) with various cancers (breast 3, kidney 1, melanoma 1, colorectal 5), developed infection: 4 local infections around the port, 1 phlebitis, 4 septicemias, 1 bacteremia were observed. In 9 cases blood cultures were positive: Staphylococcus aureus 5, Staphylococcus epidermidis 3, Streptococcus G 1. In 5 cases the same pathogen was isolated from the port and from the blood. The mean leucocyte count was 10,627/mm3 at the time of infection. The delay between the beginning of interleukin 2 treatment and the infection was 3 months. The mean dose of IL 2 administered before infection was 456 million IU. In all cases infection was controlled without lethal complication by antibiotics and catheter removal. This high incidence (8 percent) of staphylococcal infection is partly due to the skin toxicity of IL 2 and to depressed neutrophil chemotactic response. Prophylactic antibiotics are warranted during IL 2 intravenous therapy.

Adult↗
PubMed1993

[Cancer of the kidney: changes in blood lymphocyte subsets induced by treatment with interferon alpha-2b and interleukin-2r].

Twenty patients (6 females and 14 males), age range 36-70 years-old, with metastatic renal cell carcinoma (MRCC), received interferon alpha-2b (IFN-A) 10 x 10(6) units/day IM for 5 days followed by continuous i.v. infusion of interleukin-2 (IL-2) 18 x 10(6) units/day for 5 days. The median follow-up was 10 months. We observed four partial responses (20%), 13 stable (65%) and three progressive diseases (15%). The mean CD4/CD8 ratio, obtained before therapy in patients with MRCC, was compared with CD4/CD8 ratio in 51 patients with different advanced malignancy and in patients with no cancer. The CD4/CD8 ratio was higher in patients with MRCC (2.55) than in other cancers (1.474) and than in populations with no cancer (1.66 x chi 2 = 17,378). The surface phenotypes of peripheral lymphocytes were analysed by cytofluorometry in patients with MRCC during and after treatment with IFN-A and IL-2. Immune modulatory effects of therapy immediately induced a decrease of different sub-populations of lymphocytes except CD25+. Far from the first course, a rise in lymphocyte count was observed. The proliferation effect was as follows: CD4+, CD8+, CD4+ CD45RA- and CD16+ CD8- cells. Far from the second and 3rd course, the sub-populations of lymphocytes decreased, except the CD4+ and CD4- CD45RA+ cells. The CD4/CD8 ratio increased progressively during treatment. Before each course, the CD4/CD8 ratio of patients with response to treatment was higher than the CD4/CD8 ratio of patients with no response. Results were non-significant due to the small number of subjects with responses in this study.

Adult↗
PubMed1993

[Malignant melanoma of the uvea].

Intraocular melanoma is the most common primary ocular malignancy in Whites. Epidemiologic studies demonstrated the role of sun exposure as a risk for uveal melanoma. Conservative treatment techniques are indicated for localised tumors when feasible. External radiation therapy and radioactive eye plaque brachytherapy seem as effective as surgery in term of survival. High tumor doses can be safely administered with either helium or proton beams. A partial preservation of the vision is possible in most of patients. However, even for locally controlled patients, distant metastases can occur. Liver is the most frequent metastatic site, and also the first involved. Liver metastases are associated with a low response rate, to dacarbazine and nitrosourea. Recent studies using a new nitrosourea, fotemustine, administered locally through an intra-arterial catheter, show that it produces encouraging results with a good hepatic and hematologic tolerance.

Antineoplastic Agents↗
PubMed1992

[Growth factors of cultured epithelial cells of breast diseases and breast carcinoma].

Primary cultures of non-malignant human breast tissues, benign mastopathies and breast carcinomas were raised in defined culture conditions and characterized for in vitro cell proliferation. Although some mastopathies had estradiol receptors they did not respond to hormone treatment. Epidermal growth factor (EGF) was capable of stimulating the 3 types of primary culture. In contrast, dexamethasone, insulin and transferrin stimulated only the proliferation of some benign mastopathies and carcinoma cells. Cholera toxin increased the cell growth of normal tissues and mastopathies but not of carcinoma in primary cultures. Taken together, these results show that epithelial cells from mastopathies differ from one another; some are similar to non-malignant cells, whereas others are comparable to tumor cells.

Breast Diseases↗
PubMed1991

Fetal myofibroblast-like cells isolated from post-radiation fibrosis in human breast cancer.

Cells were isolated from post-radiation fibrosis biopsies of patients with recurrent breast carcinoma. These cells were identified as fibroblasts and compared with fibroblasts from normal breast tissues for their proliferative activities, chromosome number and for the presence of various components of the extracellular matrix and cytoskeleton. The proliferative activity of the fibrosis-derived fibroblasts did not significantly differ from that of normal breast fibroblasts. Both cell types required serum to grow and did not form colonies in soft agar. Cells from 2 of the 3 fibroses analyzed displayed aneuploid karyotypes with multiple structural abnormalities. All of the fibroblastic cells produced types I, III and V collagen, fibronectin and vimentin. However, in contrast to normal breast fibroblasts, fibrosis-derived cells produced high amounts of oncofetal fibronectin. In addition, fibrosis of fibroblasts also expressed the alpha-actin isoform which is specific for smooth-muscle cells. These results suggest that post-radiation fibrosis in malignant breast contains atypical fibroblasts with fetal and myofibroblastic characteristics.

Breast Neoplasms↗
PubMed1991

Growth of human breast cancer cell lines is inhibited by the somatostatin analog BIM23014.

Somatostatin has been shown to lower plasma levels of various hormones and growth factors involved in regulation of the growth of human breast cells. In the present study we examined the ability of the somatostatin octapeptide analog BIM23014 to modulate the in vitro growth of five human breast cell lines: HBL100, Hs578T, MDAMB231, T47D, and MCF7. BIM23014 inhibited the growth of the two steroid-dependent cell lines, MCF7 and T47D, in a dose-related manner. This inhibitory effect was only observed when MCF7 and T47D cells were cultivated in medium containing steroid-depleted serum. The growth of a MCF7 variant capable of growth in serum-free medium was also inhibited by BIM23014, indicating that serum factors are not required for this inhibition. In the serum-free medium, the addition of estradiol before or during treatment with BIM23014 abolished its inhibitory effects on cell growth. The studies including time course, competitive inhibition, and cross-linking of iodinated BIM23014 to its receptor revealed a specific binding on MCF7 cells and showed a single 57,000 mol wt protein band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These results support the hypothesis that BIM23014 inhibits the growth of steroid-receptor positive cells of human breast cancers through its own receptor in estradiol-free conditions.

Binding, Competitive↗
PubMed1991

[The blood-brain barrier: implications for chemotherapy in brain tumors].

The blood-brain barrier (BBB) is located between the blood and the extracellular space of the brain. This barrier is formed by the brain capillaries whose endothelial cells have tight intercellular junctions. Transcellular passage of drugs from the bloodstream to the brain occurs selectively, in a manner dependent on the ability of the molecules to penetrale through cell membranes. The blood-brain barrier is one of the main factors of chemotherapy failure in central nervous system tumors. Penetration of a molecule from the bloodstream to the brain is dependent on the compound's liposolubility, expressed by the octanol-water separation coefficient. Following intravenous administration, most drugs fail to achieve adequate levels in the central nervous system for a sufficiently long period of time. A variety of techniques have been used in an attempt to increase CNS penetration of drugs normally shut out by the blood-brain barrier: high-dose chemotherapy, intrathecal injections, intraarterial injections, induction of hyperosmolarity to make the blood-brain barrier permeable. The best results are obtained using liposoluble drugs with optimal octanol-water separation coefficients, such as fotemustine. This compound given as single drug therapy in brain metastases from malignant melanomas has yielded response rates of up to 28.2%.

Antineoplastic Agents↗
PubMed1991

[Evolution of cancer mortality. Reflexions of a physician].

Changes in cancer mortality trends in Europe and the USA are correlated with changes in the environment. Active prevention by means of antioxidants and antiproliferative agents etc should be used more extensively and advertisements regarding tobacco habits should rely more on methods intended to project a negative image of smokers. At the present time, anticancer therapies lengthen the survival of patients, which could induce bias in statistics. In the future it seems likely that they will play a greater role against cancer than early detection. Nevertheless, efforts should be made in this direction, at least with regard to young people due to the decreasing mean age of the appearance of several tumors.

Humans↗
PubMed1991

[Brain metastases of malignant melanomas].

Cerebral metastases of malignant melanoma are correlated with a very poor prognosis. Surgery of an isolated metastase can lead to a long survival but the brain lesions are frequently numerous and associated with an extracerebral diffusion. Dacarbazine (DTIC) gives a mean response rate of 21% on visceral localisations but doesn't cross the blood brain barrier (BBB). Neither do the biological response modifiers like Interleukin 2 (Il2) that leads to 25% response rate in disseminated melanoma. Nitrosoureas like carmustine (BCNU) and semustine (CCNU) have been investigated in different non randomised studies and the clinical results didn't illustrate their theorical ability to cross the BBB. Radiotherapy is also used as a palliative therapy with 7 to 16 weeks survival. Fotemustine (muphoran), a new amino acid linked nitrosourea, can give a response rate up to 28.2% in patients with cerebral metastases and the increased survival of responding patients is significant. The availability of this new drug may suggest associations with surgery and radiotherapy in the future to improve the survival of such patients.

Antineoplastic Agents↗