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C Toma

Publications and source records attributed to C Toma.

At least 37 records · Page 2Linked to original sources
PubMed1996

Effect of Vibrio cholerae non-O1 protease on lysozyme, lactoferrin and secretory immunoglobulin A.

The effect of Vibrio cholerae non-O1 protease on host defense proteins (lysozyme, secretory immunoglobulin A and lactoferrin) was studied in relation to its virulence mechanism. The proteins treated with the protease were analysed by SDS-PAGE. There was no influence of the protease on lysozyme. The protease cleaved lactoferrin into two fragments of 50 kDa and 34 kDa. N-terminal amino acid sequencing of these fragments revealed that the cleavage site was near the hinge region, between serine 420 and serine 421. This cleavage could affect the transition from open to closed configuration which is involved in iron binding and release. The anti-bacterial activity of lactoferrin was not affected by protease treatment. Secretory immunoglobulin A yielded a 42-kDa protein as the cleavage product. The susceptibility of secretory immunoglobulin A to V. cholerae non-O1 protease suggests a mechanism by which bacteria might evade the effect of this immunoglobulin.

Amino Acid Sequence↗
PubMed1996

Activation of potassium currents by inhibitors of calcium-activated chloride conductance in rabbit portal vein smooth muscle cells.

1. The conventional whole-cell recording technique was used to study the effects of the chloride channel inhibitors ethacrynic acid, anthracene-9-carboxylic acid (A-9-C) and indanyloxyacetic acid (IAA) on membrane currents in rabbit portal vein smooth muscle cells at a holding potential of 0 mV. 2. Using a pipette solution that contained 1 x 10(-4) M 1,2-bis (2-aminophenoxy)-ethane-N,N,N,N,-tetraacetic acid (BAPTA) and a normal bathing solution the addition of ethacrynic acid (2 x 10(-4) M to 1 x 10(-3) M) inhibited spontaneous transient outward currents (STOCs) and evoked a concentration-dependent current at a holding potential of 0 mV. A similar current was activated by IAA (5 x 10(-4) M to 1 x 10(-3) M) but not by A-9-C (1-5 x 10(-3) M) at a holding potential of 0 mV. 3. The amplitude of the current evoked by ethacrynic acid and IAA was linearly related to potential between -30 and 0 mV and displayed outward rectification at positive potentials. The current induced by A-9-C was evident only at potentials positive to +20 mV. 4. Glibenclamide (1 x 10(-5) M) abolished the current evoked by ethacrynic acid and IAA at potentials negative to +10 mV and partially inhibited the current positive to +10 mV. The glibenclamide-insensitive current at positive potentials was completely inhibited by 1 x 10(-3) M TEA. The A-9-C-evoked current was insensitive to glibenclamide and abolished by 1 x 10(-3) M TEA. 5. The glibenclamide-sensitive current activated by ethacrynic acid was not sustained and declined to control levels in the continued presence of ethacrynic acid. However, the outwardly rectifying current recorded at +50 mV was well maintained over the same period. 6. Outwardly rectifying currents evoked by ethacrynic acid and A-9-C were observed with a pipette solution containing 1 x 10(-2) M BAPTA in cells bathed in Ca-free extracellular solution containing 5 x 10(-4) M BAPTA and 1 x 10(-5) M cyclopiazonic acid. 7. It is concluded that all three chloride-channel blockers activated an outwardly rectifying, TEA-sensitive current. Moreover, ethacrynic acid and IAA evoked an additional glibenclamide-sensitive current which was present at all potentials between -30 and +50 mV.

Animals↗
PubMed1996

Cloning and genetic analysis of the Vibrio cholerae aminopeptidase gene.

The structural gene for the Vibrio cholerae leucine aminopeptidase (lap) was cloned and sequenced. The cloned DNA fragment contained a 1,503-bp open reading frame potentially encoding a 501-amino-acid polypeptide with a calculated molecular mass of 54,442 Da. The deduced amino acid sequence of the entire protein showed high homology with the sequence of Vibrio proteolyticus leucine aminopeptidase. The residues potentially involved in binding the zinc ions were completely conserved in the V. cholerae aminopeptidase as well as in the V. proteolyticus aminopeptidase. The recombinant protein was partially purified and characterized. The molecular mass was estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to be 34 kDa, suggesting a processing of the protein to acquire the mature form. The protease showed maximum activity at pH 9.0 and was thermostable at 70 degrees C. The substrate leucyl-p-nitroanilide was cleaved by the protease, and its activity was inhibited by EDTA and bestatin. These results suggested that the protein was a leucine aminopeptidase. The PCR analysis of lap gene distribution showed that it was widely distributed among the V. cholerae strains. It was not present in the other species examined.

Amino Acid Sequence↗
PubMed1995

Enhanced serum levels of thiobarbituric-acid-reactive substances in diabetes mellitus.

PURPOSE: To investigate whether serum levels of lipid peroxides measured as thiobarbituric-acid-reactive substances (TBARS) differ in type I and type II diabetic patients, whether serum levels correlate with late sequelae of diabetes, and whether serum levels of free vitamin E correlate with levels of lipid peroxidation by-products. PATIENTS AND METHODS: The relationship among lipids, glycosylated hemoglobin A1c (HbA1c), lipid peroxides measured as TBARS, and free vitamin E was determined in 158 patients. Fifteen of the 77 patients with type I diabetes and 39 of the 81 patients with type II diabetes had clinically apparent peripheral vascular disease or coronary artery disease, or both. RESULTS: Compared with control subjects, serum levels of TBARS were found to be significantly elevated (P < 0.001) in diabetic patients, and type II diabetic patients had significantly higher levels (P < 0.001) than type I patients. Both type I and type II diabetic patients with good metabolic control (HbA1c < 6.5%) had significantly lower (P < 0.005) TBARS levels than patients with poor metabolic control, but all groups had higher levels than the control group. Type II patients with angiopathy had significantly higher levels of TBARS than patients without angiopathy. Free vitamin E levels in control subjects and diabetic patients did not differ statistically. CONCLUSION: Serum levels of TBARS were significantly increased in all patients suffering from diabetes mellitus, whereby TBARS levels did not depend on the total amount of circulating lipids. It can be suggested that the enhanced lipidperoxidation is contributed to an increased formation of free radicals in diabetes mellitus.

Adult↗
PubMed1995

Effects of tyrosine kinase inhibitors on the contractility of rat mesenteric resistance arteries.

1. A pharmacological characterization of tyrosine kinase inhibitors (TKI) belonging to two distinct groups (competitors at the ATP-binding site and the substrate-binding site, respectively) was performed, based on their effects on the contractility of rat mesenteric arteries. 2. Both the ATP-site competitors (genistein and its inactive analogue, daidzein) and the substrate-site competitors (tyrphostins A-23, A-47 and the inactive analogue, A-1) reversibly inhibited noradrenaline (NA, (10 microM)) and KCl (125 mM) induced contractions, concentration-dependently. Genistein was slightly but significantly more potent than daidzein; the tyrphostins were all less potent than genistein, and there were no significant differences between the individual potencies. The tyrosine kinase substrate-site inhibitor bis-tyrphostin had no inhibitory effect. 3. Genistein, daidzein, A-23 and A-47 each suppressed the contraction induced by Ca2+ (1 microM) in alpha-toxin permeabilized arteries. A-1 and bis-tyrphostin had little or no effect on contraction of the permeabilized arteries. 4. Genistein was significantly more potent than daidzein with respect to inhibition of the contraction induced by 200 nM Ca2+ in the presence of NA (100 microM) and GTP (3 microM). The effect of A-23, A-47, A-1 and bis-tyrphostin was similar in permeabilized arteries activated with Ca2+ (200 nM) + NA (100 microM) + GTP (3 microM) and permeabilized arteries activated with 1 microM Ca2+. 5. Genistein (30 microM) reduced the fura-2 measured intracellular calcium activity ([Ca2+]j) in arteries stimulated with NA but had no effect on [Ca2+]i in arteries stimulated with KCl (125 mM).6. The potent effect of the TKIs in this study is consistent with a role for tyrosine kinases in the mechanisms which regulate both cytoplasmic Ca2+ levels and the effect of Ca2+ on the contractile apparatus in smooth muscle cells in resistance arteries. However, the results must be interpreted cautiously because the enzyme inhibitors may have a poor specificity in intact tissues and because the presumed inactive analogues had potent effects.

Animals↗
PubMed1994

The protective potency of two commonly used cardioplegic solutions on cultured endothelial cells exposed to free-oxygen radicals injury.

Human umbilical vein endothelial cells were incubated with Bretschneider and St. Thomas II cardioplegic solution followed by a stimulation with cumene hydroperoxide (CHPO), which was used as an oxygen radicals generating agent. A statistically significant decrease of intracellular high energy phosphates (adenosine-5-trisphosphate: ATP; creatine phosphate: CP) compared to controls was observed in response to Bretschneider cardioplegia and CHPO. Furthermore, significant rises in prostaglandin I2 (prostacyclin; PGI2) production and lipidperoxidation were measured. The authors failed to record such alterations of endothelial cell metabolism for the St. Thomas II cardioplegic solution. They could also demonstrate that the cellular protection against oxygen radicals exerted by the St. Thomas II solution is attributable to procaine. The enhanced cytotoxicity of CHPO observed in presence of the Bretschneider solution was found to be partially caused by its constituent L-histidine, which led to significant decreases of high energy phosphates and increased lipidperoxidation when cells were subsequently treated with CHPO. However, alterations of high energy phosphate content initiated by CHPO and amplified by the Bretschneider solution could not be inhibited by adding procaine. Simultaneous pretreatment of cells with the Bretschneider solution and procaine and stimulation with CHPO resulted in decreases of ATP and CP, as observed using the Bretschneider cardioplegia alone.

Adenosine Triphosphate↗
PubMed1993

Midterm experience with the cementless Zweymueller system. Results of a minimum five-year follow-up study.

Eighty-five patients with 96 cementless press-fit hip implants were followed over a period of at least 5 years postoperatively. The average Harris score was 87.5 points. One socket had to be exchanged 4 years postoperatively because of aseptic loosening. Additionally, 5 sockets developed radiolucent lines, one of them totally around the socket, but without signs of subsidence progression. In no case was a change of the stem necessary; one stem subsided 4 mm within the first postoperative year but was stable at the last follow-up investigation. One patient was personally dissatisfied with the outcome of the operation. No implant-specific complications such as breakage of the implant, breakage or crack of the stem, or blasting of the pelvic girdle by socket-screwing were observed.

Activities of Daily Living↗
PubMedDate not supplied

[Cement-free Zweymüller hip system. Results of a 5-year follow-up study].

85 patients with 96 cementless pressfit hip implants were followed over a period of at least 5 years postoperatively. Average Harris score was 87.5 points. One socket had to be exchanged because of aseptic loosening. Additionally, 5 implants developed radiolucent lines, only one of them totally around the socket. In no case an exchange of the stem was necessary; one stem initially sank by 4 mm axially but was stable at the last follow-up investigation. Only one patient personally is dissatisfied with the outcome of the operation. In no case, implant specific complications such as breakage of the implant, breakage or crack of the stem, or shattering of the pelvic girdle by acetabular-screwing could be observed.

Adult↗
PubMedDate not supplied

Role of intracellular calcium for noradrenaline-induced depolarization in rat mesenteric small arteries.

We have investigated the effect of intracellular calcium levels for membrane potential during noradrenaline application in isolated small arteries. Rat mesenteric small arteries were mounted for isometric tension measurement. Smooth muscle membrane potentials were measured by conventional intracellular electrodes, and intracellular calcium concentration was measured using Fura-2 fluorescence. Under control conditions, noradrenaline caused contraction and depolarization from -55.5 to -29.3 mV. In intact arteries, depleting intracellular calcium stores with thapsigargin caused smooth muscle hyperpolarization and inhibited contraction to noradrenaline. In de-endothelialized vessels, thapsigargin still depleted calcium stores, but did not affect either the depolarization or contraction caused by noradrenaline. In noradrenaline-activated vessels, inhibition of calcium influx by amlodipine caused tension and calcium levels to fall to near-baseline levels, but membrane potential returned by only 55%. Treatment with a combination of thapsigargin, D-600 and BAPTA-AM inhibited the tension and calcium responses to noradrenaline, but the membrane potential response was reduced by only 34%. Acute reduction of extracellular chloride concentration caused similar, small depolarization at rest and during noradrenaline exposure. It is concluded that an elevation of intracellular calcium concentration is not essential for noradrenaline depolarization, although part of the depolarization is associated with the raised intracellular calcium level.

Amlodipine↗
PubMedDate not supplied

[The use of echography in the diagnosis of autoimmune thyropathies].

Ultrasonography is a first line method in thyroid imaging. The aim of this study was to evaluate the usefulness of thyroid ultrasonography in the diagnosis of thyroid autoimmune diseases (TAD): Graves' disease (GD) and autoimmune thyroiditis (AT)--Hashimoto's and atrophic thyroiditis. Ultrasonography was performed with a 7.5 MHz transducer in 1033 consecutive patients. The excluding criteria was nodular goiter, irrespective of its function. Thyroid volume was calculated using the formula of a rotating ellipsoid. Hypoechogenicity was appreciated using a qualitative scale: 1 = absent, 2 = mild, 3 = moderate, 4 = marked. In patients with TAD thyroid hypoechogenicity was significantly higher than in normal subjects (2.5 +/- 1 in GD and 2.7 +/- 1 in AT, vs. 1.2 +/- 0.6 in normal subjects, p < 0.0001). The specificity of the test in identifying TAD was 91.4%, the sensitivity was 68.6% for GD and 80.8% for AT, positive predictive value was 91.5%, and negative predictive value 91.5%. Ultrasonography is useful in identifying patients with probable autoimmune thyroid diseases, being useful in epidemiological studies and having an important contribution in confirmation of the diagnosis.

Adult↗
PubMedDate not supplied

[The prognostic factors for survival in advanced forms of non-small-cell lung cancer].

UNLABELLED: This study attempted to determinate the prognostic value for survival of various clinical, biological and therapeutical prognostic factors in patients with non-resectable non-small cell lung cancer (NSCLC). METHOD: We performed a retrospective study on 236 patients with histologically proved unresectable NSCLC. We collected 36 variable and analysed them by univariate and multivariate methods in order to establish their influence on survival. RESULTS: The global estimated median survival time was 10 month. In univariate analysis were significantly related to survival: age (> 60 years), weight loss (> 5%), local extend of of disease, Karnofsky performance index (< 70%), stage of disease (stage IIIA vs. IIIB, IV), hemoglobinemia (< 10 g%), calcemia, platelet count, radiotherapy total dose (< 50 Gy), Cisplatin chemotherapy. In a Cox regression model, the explanatory variables were: age > 60 years, Karnofsy performance index 70%, stage IIIB and IV, thoracic total radiotherapy dose < 50 Gy. These results led to a classification of the patients into three subgroups (prognostic index). CONCLUSION: We confirm by our analysis the role of independent factors for survival and we obtained three prognostic groups, the best one needs a radio-chemotherapy association.

Aged↗