The effect of nitric oxide donors and L-arginine on the gastric electrolyte barrier.

The potential difference across the stomach wall (PD) is determined by the gastric mucosal barrier. The decrease in the PD evoked by "the barrier breakers", e.g. aspirin, ethanol or bile acids is believed as a sensitive index of the mucosal damage. The effect of glyceryl trinitrate (GTN), isosorbide dinitrate (IDN) and molsidomine (MOL)--all exogenous donors of nitric oxide (NO), as well as L-arginine (L-ARG), which is a substrate for NO-synthase and Nomega-nitro-L-arginine (L-NNA), a non-selective NO synthase inhibitor on the gastric electrolyte barrier were studied against the gastric damage induced by ethanol. All NO donors given intragastrically alone caused only moderate, not significant changes in the PD and failed to affect the mucosal barrier, while L-NNA slightly decreased the PD. The NO donors and L-arginine applied as pretreatment prior to ethanol resulted in diminishing of its damaging action that was similar for all these drugs, while L-NNA intensified both the injury and the drop in the PD values caused by ethanol. In summary, our results showed the protective effect of endogenous nitric oxide from L-ARG and that originating from GTN, MOL and IDN on the gastric electrolyte barrier, supporting involvement of nitric oxide in the mechanism of gastric protection in the stomach.

[Changes in electrical potentials of gastric mucosa during various types of experimental hypoxia]. / Zmiany potencjalów elektrycznych blony sluzowej zoladka w warunkach doswiadczalnej hipoksji wywolanej róznymi czynnikami.

In experiments performed on anaesthetized male and female Wistar rats the effects of different types of hypoxia on the electrical potential difference (PD) between the inner and the outer sides of the gastric wall were examined. The PD was determined by mean of the Digital Multimeter VC-10T, Unitra, and the calomel electrodes connected with the KCl-agar bridges. There were four series of experiments carried out in which hypoxia was produced by: I--low atmospheric pressure (hypobaric hypoxia) corresponding with the altitudes of 2500, 5500, 8500 and 10,500 m above sea level, II--1 min. nitrogen breathing (anoxic anoxia), III--bleeding ca. 1% of the body weight (anemic hypoxia), IV--the gastric vessels ligation (ischemic hypoxia). There were also performed the adequate control experiments of each series. In all types of hypoxia (I--IV) a decrease in the PD was observed. The value and rate of this decrease were dependent on the type, grade, duration and rate of hypoxia. In the conditions of the hypobaric hypoxia simulated altitude 10,500 m only evoked the statistically significant PD drops, by 31%. The nitrogen breathing caused the PD decrease by 23% and the anemic hypoxia by 18%. In the ischemic hypoxia the total disappearance of the potential difference (PD = 0 mV) was observed. In the control experiments small non significant fluctuations, not exceeding 4%, occurred only. The decrease in the PD of the gastric wall observed during hypoxia could be explained by the changes in the membrane transport e.g. the back-diffusion of Na+, Cl-, and H+ ions.

Internal validation of a telemedical system for monitoring patients with chronic respiratory diseases.

One of the most promising and innovative developments in medicine are telemedical systems. The system PulmoTel 2010 and its internal validation are presented, focusing on the system architecture, hardware, software and communication solutions. PulmoTel 2010 consists of a distant server managing users and medical devices, as well as data transmission, processing, storage and presentation. The server cooperates with home units used by patients, capable of performing lung function tests. All the elements communicate via the Internet, however other media, as wire and mobile telephony, can be additionally applied in regions with a less developed infrastructure. Internal validation of the system was performed using data generated by application simulating features of a home unit. It demonstrated an appropriate operation of the overall system and fulfillment of the main objectives of the project.

The effect of ethanol-caffeine interaction on the gastric mucosal barrier.

Potential difference across the stomach wall (PD) is determined by the gastric mucosa electrolyte barrier. The decrease in the PD caused by the "barrier breakers" e.g. aspirin, alcohol and cholic acids is a sensitive index of mucosal damage. We studied the effect of interaction between alcohol and caffeine on the PD in the anesthetized rats. The intragastric administration of 1 ml of 40 vol.% ethanol solution decreased the PD by 39%, of 10 mg of caffeine sodium benzoate by 22% and the simultaneous administration of alcohol and caffeine by 53%. These results indicate that caffeine may enhance the damaging effect of alcohol on the gastric mucosal barrier.

Light-transmittance predictions under multiple-light-scattering conditions. I. Direct problem: hybrid-method approximation.

Our aim is to present a method of predicting light transmittances through dense three-dimensional layered media. A hybrid method is introduced as a combination of the four-flux method with coefficients predicted from a Monte Carlo statistical model to take into account the actual three-dimensional geometry of the problem under study. We present the principles of the hybrid method, some exemplifying results of numerical simulations, and their comparison with results obtained from Bouguer-Lambert-Beer law and from Monte Carlo simulations.

Light-transmittance predictions under multiple-light-scattering conditions. II. Inverse problem: particle size determination.

Our aim is to present the application of the hybrid method presented in part I to an inverse procedure to determine particle size and concentration under multiple-scattering conditions. The hybrid method is introduced as a combination of the four-flux method with coefficients obtained from Monte Carlo statistical simulations to take into account the actual three-dimensional geometry. Then an inversion scheme is expanded to enable the application of the hybrid method to particle size and concentration determination. We present the inversion method as well as exemplifying results of spectrum inversions.

Interference of psychotropic drugs with the injuring action of ethanol on gastric mucosal barrier.

The aim of this study was to establish whether some psychotropic drugs, applied to patients under influence of alcohol, may potentiate its damaging action on gastric mucosal barrier. A sensitive index of such damage is a decline of the potential difference (PD) across the stomach wall. The experiments were carried out on Wistar rats of either sex, anesthetized with urethane-chloralose. The PD values were assayed with an apolarization method. The investigated solutions were administered intragastrically by gavage. Ethanol at a concentration of 40% v/v depressed PD by 39%. The investigated psychotropic drugs did not change PD by themselves but given in combination with ethanol caused significant decline of PD: diazepam (0.4 mg/kg) by 58%, chlorpromazine (6.7 mg/kg) by 59%, imipramine (2 mg/kg) by 48%, amitriptyline (4 mg/kg) by 49%, phenytoin (4 mg/kg) by 53%, pyridinol (0.3 mg/kg) by 58%. Intragastric administration of water did not change PD. The results indicate that while psychotropic drugs given alone do not affect significantly the gastric mucosal barrier, they may potentiate the damaging action of ethanol on this barrier.