Tetrodotoxin blocks native cardiac L-type calcium channels but not CaV1.2 channels expressed in HEK cells.

Tetrodotoxin (TTX) has been believed for a long time to be a selective inhibitor of voltage-gated fast Na(+) channels in excitable tissues, including mammalian myocardium. Recently TTX has been shown to block cardiac L-type Ca(2+) current (ICa,L). Furthermore, this inhibition was ascribed to binding of TTX to the outer pore of the Ca(2+) channel, contributing to the selectivity filter region. In this study the TTX-sensitivity of Cav1.2 channels, expressed in HEK cells, was tested using the whole cell version of the patch clamp technique and compared to the TTX-sensitivity of native canine ICa,L. Cav1.2 channels mediate Ca(2+) current in ventricular myocardium of various mammalian species. Surprisingly, TTX failed to inhibit Cav1.2 current up to the concentration of 100 µM - in contrast to ICa,L - in spite of the fact that the kinetic properties of the ICa,L and Cav1.2 currents were similar. The possible reasons for this discrepancy are discussed. Present results may question the suitability of a single pore-forming channel subunit, expressed in a transfection system, for electrophysiological or pharmacological studies.

Erythropoiesis-stimulating agent withdrawal and oxidative stress in hemodialysis.

AIMS: Variation of the action of erythropoiesis-stimulating agent (ESA) may modify oxidative stress in hemodialyzed (HD) patients. Our aim was to follow changes of oxidative stress during withdrawal and subsequent resumption of ESA therapy. PATIENTS AND METHODS: After a 14-day suspension of epoietin-beta treatment, 11 HD patients received epoietin-beta and 10 patients darbepoietin-alpha. The whole blood oxidized and reduced glutathione (GSSG, GSH) and erythrocyte malondialdehyde (E-MDA) concentrations and the erythrocyte superoxide dismutase (E-SOD) and catalase (E-CAT) activities were determined before the ESA-free interval (baseline) and at Weeks 2, 6, 10 and 14. RESULTS: In both groups, the ratios GSSG/ GSH were increased at Weeks 2 and 6 (p < 0.001). The E-MDA levels were elevated (p < 0.01) and the E-SOD activities were decreased (p < 0.001) at Week 6. By Week 14, these markers had returned to the baseline, whereas the GSH (p < 0.001) and E-CAT activity levels (p < 0.001) had increased. CONCLUSIONS: An increase in oxidative stress was revealed by the ratio GSSG/GSH directly after the short-term withdrawal of epoietin-b therapy in HD. This new finding may have implications in conditions involving transiently depressed ESA action. For both ESAs, the early phase of readministration was associated with similarly increased oxidative stress, with a subsequent return to the baseline level.

Use of glucose consumption rate (GCR) as a tool to monitor and control animal cell production processes in packed-bed bioreactors.

For animal cell cultures growing in packed-bed bioreactors where cell number cannot be determined directly, there is a clear need to use indirect methods that are not based on cell counts in order to monitor and control the process. One option is to use the glucose consumption rate (GCR) of the culture as an indirect measure to monitor the process in bioreactors. This study was done on a packed-bed bioreactor process using recombinant CHO cells cultured on Fibra-Cel disk carriers in perfusion mode at high cell densities. A key step in the process is the switch of the process from the cell growth phase to the production phase triggered by a reduction of the temperature. In this system, we have used a GCR value of 300 g of glucose per kilogram of disks per day as a criterion for the switch. This paper will present results obtained in routine operations for the monitoring and control of an industrial process at pilot-scale. The process operated with this GCR-based strategy yielded consistent, reproducible process performance across numerous bioreactor runs performed on multiple production sites.

The roles of platelet function, thromboxane, blood lipids and nitric oxide in hypertension of children and adolescents.

The roles of platelet function, plasma lipids and nitric oxide (NO) were studied in adolescent patients with essential hypertension (JEHT group), with chronic renal failure (CRF) associated with hypertension (CRFH group), and CRF patients with normal blood pressure (CRF group), as compared with normal controls (cont. group). Platelet aggregation and the thromboxane B(2)(TxB(2)) level were significantly higher in the JEHT and CRFH groups as compared with the cont. group, whereas they were significantly lower in the CRF group. On the other hand, the platelet cAMP level was significantly lower in the JEHT and CRFH groups than in the cont. group. The plasma NO level was significantly higher only in the JEHT as compared with the cont. group (120 +/- 39 and 89 +/- 21 microM, respectively). The plasma total cholesterol, triglyceride and LDL cholesterol concentrations were normal in the JEHT group, but high in the CRF and CRFH group, the HDL cholesterol level was lower in the CRF and CRFH groups as compared with the cont. and JEHT groups. There was a positive correlation between the platelet aggregation and the TxB(2)level and between the BP and the platelet aggregation. In conclusion, hyperlipidaemia is commonly present in uraemia with haemodialysis, but is not specific for hypertension in children, while an increased platelet function is frequently associated with hypertension. The increased NO level might play a compensatory role in JEHT.

Rare case of the utero-vesical fistula caused by intrauterine contraceptive device.

The vesico-uterine fistula is a very rare disease. There have only been 150-200 causes. We are reporting on a case in which the chronic fistula was caused by an IUD having been placed 4 years ago and it "wandered" through the bladder. A 30 year-old patient in 1992 and IUD was inserted. She had gynecological controls twice, in 1993 last time. She has problem of urination very often. A cyclical bladder bleeding drew the attention to the disease. In ambulanterely performed cystoscopy we found an IUD perforating towards the interior of bladder in the borderline of its bottom and back wall and was situated in the bladder with its 3/4. We have removed it with forceps. After six weeks of expectation and strict observation did we want to manage the fistula after having consolidated the symptoms of the inflamed surroundings. During the operation we have noticed a wallment size mass of scar between the uterus and the bladder expanding to the height of the orifice of the uterus. The scarily fixed bladder has been separated from the cervix and the scarry wall of the fistula has been cut out. We have brained the cervix towards the vagina and then we've sutured the cervix and the bladder with Dexon 'O' treat, as well. We have interposed a surgical net between the cervix and the bladder followed by blood-clotting and peritonisation. We should take the follows into consideration: careful separation, fine operative technique, and strong well absorbing thread as well as trying to keep the organ. In our opinion the bioplast--interpositum used on our case maker the efficiency of the operation higher.

[Retrospective study 10 years after plastic surgery for sacrococcygeal pilonidal sinus]. / Sacrococcygealis sinus pilonidalis miatt végzett plasztikai eljárásunk eredményességének 10 éves utánvizsgálata.

The authors give a brief summary on the etiology and pathomechanism of the sacrococcygeal pilonidal sinus. They have distinguished the congenital, cystic deformation (dermoid cyst) from the pilonidal sinus which is considered to be an adventitious illness. During ten years (1976-1985) 208 patients were operated on with the method the authors applied. Only one early recurrence was registered and 7.2% of the patients recovered from secondary healing. Delayed recurrences were analysed according to questionnaires. From 151 of the questionnaires only three male patients complaints referred to delayed recurrence.

[Percutaneous nephropexy]. / Percutan nephropexia.

We present a new, minimally invasive method for the treatment of nephroptosis. We are suggesting the more spreaded use of this method after the good results we found during the long term observation of our 40 patients with percutaneous nephropexy.