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Biomedical subjects

J Alexandre

Publications and source records attributed to J Alexandre.

At least 37 records · Page 2Linked to original sources
PubMed1998

[Apical hypertrophic cardiomyopathy associated with coronary artery disease].

A fifty-nine year old man, known to have hypertrophic cardiomyopathy, presented worsening of angina. Multivessel coronary artery disease was diagnosed, and he underwent myocardial revascularization (mammary and two safenous grafts were implanted) with good evolution and reduction of left atrium dimension.

Arterial Occlusive Diseases↗
PubMed1998

[Cancer of the kidney in the adult].

Renal cell carcinoma is a frequent disease. Recently, its incidence has been rising. Kidney tumors are detected more frequently by the newer radiologic techniques, but the diagnosis is steel difficult and occurs often late in the natural history of the disease. A high proportion of patients have metastases at diagnosis or after initial surgery. Many types of systemic therapy have been studied but resistance to radiotherapy and chemotherapy is the rule. There is a potential role for immunomodulation in the inhibition of tumor growth but clinical issue remain uncertain. In this review we discuss recent developments in epidemiology, histologic classification, tumor biology, methods of diagnosis, surgical techniques and immunotherapy for patients with metastatic disease.

Adult↗
PubMed1997

[High-dose methotrexate and cerebral neurotoxicity. Apropos of a case of arachnoiditis].

BACKGROUND: High-dose methotrexate has been used as a therapeutic strategy in osteosarcoma for 20 years. Cerebral neurotoxicity is frequent. CASE REPORT: A 21-year-old patient with non-metastatic osteosarcoma was given high-dose methotrexate prior to surgery. He developed subacute encephalitis and arachnoiditis after intravenous injection of methotrexate. COMMENTS: Although pharmacokinetic monitoring and leucovorin rescue is helpful in controlling systemic toxicity, cerebral toxicity with acute, subacute or delayed reactions may occur, depending on the administration route and use of the folate antagonist. Generally, acute arachnoiditis and subacute encephalitis are reversible and occur respectively after intrathecal methotrexate and intravenous high-dose methotrexate, while the chronic delayed leukoencephalopathy usually begins several months after a combination regime using intrathecal methotrexate, intravenous methotrexate and cerebral irradiation.

Adult↗
PubMed1997

6-Day continuous infusion of high-dose ifosfamide with bone marrow growth factors in advanced refractory malignancies.

Ifosfamide is an analogue of cyclophosphamide active in the treatment of numerous tumours. Although its use by continuous infusion seems to be responsible for less toxicity, differences of efficacy and toxicity, observed according to its doses and schedules of administration, still remain debated. The objective of this study was to assess the toxicity of high-dose ifosfamide given by continuous infusion over 6 days and its therapeutic activity in various advanced tumours. Twenty-six patients were treated with 14 g/m2 ifosfamide, an equal dose of MESNA, and routine granulocyte- or granulocyte/macrophage-colony-stimulating factor during the intercycle. Courses were repeated every 3 weeks until disease progression or unacceptable toxicity occurred; 75 cycles were administered. The mean number of cycles per patient was 3 (range 1-11). Extrahaematological toxicity was manageable in most patients, WHO grade II or more neurological (5 patients) and renal (5 patients) toxicities occurring in those heavily pretreated with platinum compounds and presenting peritoneal disease. WHO grade III or more neutropenia occurred in 60% of cycles, while grade III-IV thrombocytopenia and anaemia were observed in 19% of them. Three partial responses (germ-cell tumour, chondrosarcoma, soft-tissue sarcoma) and one complete response (metastatic osteosarcoma) were assessed, all in patients with tumours refractory or resistant to standard-dose ifosfamide, which underlines the possibility of circumventing the resistance to ifosfamide given in conventional schedules. The present results confirm previous reports of changes in the therapeutic index of ifosfamide according to its dose and administration schedule.

Adolescent↗
PubMed1997

A gene involved in both protein secretion during growth and starvation-induced development encodes a subunit of the NADH:ubiquinone oxidoreductase in Myxococcus xanthus.

The secretion of numerous proteins during vegetative growth of Myxococcus xanthus, and the multicellular development cycle induced upon starvation of these bacteria, are partially interrelated in so far as mutants impaired in extracellular protein production are unable to undergo development. We have cloned and sequenced a gene in which a Tn5 insertion leads to a decrease in the production of most, if not all, extracellular proteins, and prevents development and sporulation. The deduced protein is homologous to the putative ubiquinone-binding subunit of bacterial and mitochondrial NADH:ubiquinone oxidoreductases (complex I). This is the first example of the presence of this complex in a bacterium from subclass delta of the proteobacteria. This gene is expressed during growth and during early development. As its disruption by Tn5 does not impair growth of the mutant strain, we assume the presence of a second alternative NADH oxidoreductase, and suggest that the phenotypic alterations caused by the mutation are due to a decrease in the proton-motive force.

Bacterial Proteins↗
PubMed1997

Human T-cell lymphotropic virus-1-positive T-cell leukemia/lymphoma in a child. Report of a case and review of the literature.

Adult T-cell leukemia/lymphoma is a monoclonal T-cell neoplasm associated with human T-cell lymphotropic virus-1 (HTLV-1) that occurs almost exclusively in adults. This report concerns a Romanian girl who had recurrent skin eruptions since infancy, subcutaneous tumors in childhood, and peripheral blood lymphocytosis, which initially developed at the age of 12 years. The circulating lymphocytes were of helper T-cell immunophenotype. Serologic studies demonstrated a number of HTLV-1 antigens in the child and her mother, and molecular analyses revealed monoclonal T-cell-receptor gamma gene rearrangement and detectable HTLV-1 proviral DNA. Conventional cytogenetic studies revealed a t(3;6)(q23;q27) chromosome translocation in most of the neoplastic cells. The patient initially responded well to interferon alfa therapy and showed regression of skin lesions and diminished lymphocytosis, but 4 years later, she developed massive lymphadenopathy and leukemic infiltration of the breast. At last clinical follow-up, at the age of 17 years, the patient had stable low-level peripheral lymphocytosis and subcutaneous tumors while being continuously treated with interferon alfa. Our review of the literature revealed six additional children with HTLV-1-associated T-cell leukemia/lymphoma, including one case with a similar clinical presentation and ethnic background. To our knowledge, the t(3;6)(q23;q27) translocation identified in this patient's neoplasm has not been previously reported in adult T-cell leukemia/lymphoma cases and may explain the early onset of disease. Although adult T-cell leukemia/lymphoma is rare in Romania, the identification of healthy carriers and vertical transmission raise the possibility that Romania might be an endemic region for HTLV-1 infection.

Base Sequence↗
PubMed1996

Hypothyroid patients showing shortened responsiveness to oral iodized oil have paradoxically low serum thyroglobulin and low thyroid reserve. Thyroglobulin/thyrotropin ratio as a measure of thyroid damage.

In Central Africa, all of northern Zaire is very severely deficient in iodine. A peculiar feature of this endemia is that iodine deficiency and the ensuing thyroid gland stimulation not only leads to goitre formation but also to progressive thyroid involution and to myxoedematous cretinism. An iodine supplementation trial based on oral administration of small doses of iodine was made in 81 schoolchildren. All of them received a small dose of iodine (0.1 ml containing 48 mg) per os and the thyroid status was followed during 4 months. Blood and urine samples were collected at the start of the study, then 2 weeks, 2 months and 4 months after iodine administration. Before iodine supplementation the mean urinary iodine level was 0.18 +/- 0.02 micromol/l, and 10% of the subjects had a urinary iodine level below 0.08 micromol/l. Fifty-two percent of the subjects had a serum thyrotropin (TSH) level above 10 mU/l. All the subjects responded to the administration of iodine. and all of them recovered a euthyroid status. Most of them were still euthyroid at the end of the study. However. within 4 or even 2 months, some subjects (15 % of the total) reverted to hypothyroidism. At the entry of the study these subjects were all hypothyroid and had elevated TSH and paradoxically low serum thyroglobulin (TG) values. In myxoedematous cretins living in the same area, even lower serum TG levels were found. Together with the absence of goitre, a paradoxically low serum TG Suggests a low thyroid reserve, and in the present case a reduced amount of functional thyroid tissue. We show that the serum TG/TSH ratio may be used as a predictive index of thyroid reserve and of positive response to iodine administration. These data further suggest that thyroid damage is not confined to myxoedematous cretins. but is widely distributed in the phenotypically normal population. Widely distributed thyroid damage may render iodine prophylaxis based on oral administration unpredictable.

Administration, Oral↗
PubMed1996

[Bladder neoplasms and cyclophosphamide. Apropos pf 3 cases amd review of the literature].

We report three new cases of bladder cancer occurring in patients treated by cyclophosphamide (Endoxan): two patients had Waldenström disease and were treated during 7.5 and 7 years respectively (total received dose of 220 and 190 g respectively). The third patient was treated for autoimmune erythroblastopenia and the bladder cancer occurred 5 years after treatment by cyclophosphamide (39 g during 3.3 years). Bladder cancers after cyclophosphamide treatment are generally transitional cell carcinomas. They are observed after an oral treatment, generally given for more than one year. A cumulative dose of more than 20 g is the principal risk factor, with a median interval from treatment to tumor of 7 years. No other risk factor has been identified (tobacco, age, sex, hemorrhagic cystitis). The relative risk of bladder cancer is estimated between 7 and 9, and seems proportional to the cumulative dose of cyclophosphamide. The first hypothesis to explain bladder cancer occurrence is a carcinogenic effect of one of the cyclophosphamide metabolites, acrolein, but the immunosuppressive effect of cyclophosphamide may play a role. The risk of secondary bladder cancer implies to limit the use of cyclophosphamide, particularly in non malignant disease, and to closely watch the patient especially by way of annual cystoscopy.

Aged↗
PubMed1990

Effect of d-myo-Inositol 1,4,5-Trisphosphate on the Electrical Properties of the Red Beet Vacuole Membrane.

The effect of channel opening in the tonoplast by d-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P(3)] has been examined on red beet (Beta vulgaris) vacuoles. Patch-clamp measurements of the vacuolar potential and current were performed on vacuoles isolated in 0.1 micromolar free Ca(2+) medium. With vacuoles clamped at +30 millivolts, the Ins(1,4,5)P(3) induced changes in current were depending on the Ca(2+) buffer strength in the external medium. The spontaneous depolarization of vacuoles in which H(+)-pumps were activated by 5 millimolar MgATP was increased from +6 to +18 millivolts by 1 micromolar Ins(1,4,5)P(3). We have interpreted our data by assuming that even with 2 millimolar EGTA to buffer Ca(2+) at 0.1 micromolar in the external medium, Ins(1,4,5)P(3) released enough Ca(2+) from the vacuole to produce an accumulation of this ion near the tonoplast. Apart from their dependency with free Ca(2+) in the cytoplasm, the electrical properties of the tonoplast could be depending on the Ins(1,4,5)P(3) and Ca(2+) buffer values in the cytoplasm.

Journal Article↗
PubMed1987

Microelectrode Measurements on Red Beet Vacuole : Biological Effect of Na OR NO(3) Ions, Diffusing from the Microelectrode.

Glass microelectrodes filled with 3 molar KCl are widely used to measure intracellular potentials and it is usual to try to minimize their electrolyte loss. In these experiments we have used the ionic leak of our microelectrodes, filled with various salt solutions, to introduce a given ion into the red beet vacuole. This allowed us to show that NO(3) (-) ions reduce the magnitude of the current spectral density while they do not change the resistance of the tonoplast. This is true when NO(3) (-) is either added to the external medium or used as the microelectrode filling solution. This can be interpreted by a NO(3) (-) effect on the vacuolar side of the tonoplast, resulting in an inhibition of the ion transporting ATPase. Replacing K(+) by Na(+) ions in the medium has no effect on tonoplast resistance (R(s)). On the contrary, when ions leaking from the microelectrode are H(+), Li(+) or K(+), R(s) is close to 4 kilohm square centimeter, whereas R(s) is of the order of 30KOmega square centimeter when Na(+) are the leaking ions. We also found a possible correlation between the presence of a Lorentzian in the current spectral density (cut-off frequency = 2 hertz) and a Cl(-) efflux from the vacuole. This could be explained by the existence of Cl(-) channels on the tonoplast.

Journal Article↗
PubMed1986

Electrical noise measurements on red beet vacuoles : another way to detect the ATPase activity.

The vacuolar potential (V(vac)) and its fluctuations were recorded in red beet vacuoles (Beta vulgaris L.). Measurements with vacuoles in their suspension medium gave V(vac) = 10 +/- 2 millivolts (referred to the external medium) when 3 molar KCl microelectrodes were used. Buffering the microelectrode filling solution at pH 7.7 reversed the sign of the potential: V(vac) = -7 +/- 2 millivolts. The magnitude of the potential fluctuations was lowered by dilution (5-1000 times) with the suspension medium containing components released by the cells during the mechanical preparation. Fluctuations were decreased by 50 millimolar KNO(3) while they were enhanced by 5 millimolar ATP-Mg. No noticeable change in membrane resistance was detected. The presence of an ATPase bound to the tonoplast may explain the recorded noise spectra. These spectra imply a close connection between the rate of ATPase functioning and the magnitude of ionic fluxes across the tonoplast. It is suggested that noise analysis could be used to detect ATPase (or related enzyme) activity in vacuoles. Possible use of H(+) diffusion through a buffered microelectrode, to modify intravacuolar pH, is also suggested.

Journal Article↗
PubMed1985

Voltage Noise in Acer pseudoplatanus Cells : Basic Cellular Noise and Gramicidin a Induced Noise.

The present contribution is devoted to studying the electrical noise of Acer pseudoplatanus cells in culture suspensions. Spontaneous voltage noise of the cells was recorded by means of a microelectrode inserted in the vacuole. The small signal impedance of the cell was measured so that it was possible to study the intensity spectra of the noise. We recorded intensity spectra with cells incubated in 10(-3) molar gramicidin A. Difference spectra showed characteristics of a channel noise. By using the calculated conductance of gramicidin A in an artificial membrane, and by simplifying assumptions for the ionic transports through plasmalemma and tonoplast, we were able to estimate the electrochemical potential difference for K(+) ions across the plasmalemma (3.2 +/- 1 millivolt).

Journal Article↗
PubMed1982

Absence of islet alpha cell function in pancreatectomized patients.

Plasma immunoreactive glucagon, C-peptide and substrates (glucose, lactate, and alanine) were measured in 21 pancreatectomized patients and 28 patients with chronic calcifying pancreatitis during arginine infusion. Results were compared with those obtained in control and in insulin-dependent diabetic subjects, and in pancreatectomized subjects receiving a combined infusion of glucagon and arginine or somatostatin and arginine. Plasma immunoreactive glucagon in the pancreatectomized patients was 230 +/- 26 pg/ml (control subjects 100 +/- 13 pg/ml, p less than 0.001), but was unchanged following arginine or somatostatin. Following ethanol extraction of plasma it became undetectable. Similar results were obtained in patients with chronic pancreatitis. In contrast to the insulin-dependent diabetic subjects, no changes in blood glucose, lactate, and alanine concentrations were found during arginine infusion in the pancreatectomized or pancreatitis patients. Addition of glucagon restored the metabolic response to arginine in the pancreatectomized patients. Our results confirm previous smaller studies that in pancreatectomized patients, A cell function is absent or insignificant.

Adult↗