Biomedical subjects

W Janusz

Publications and source records attributed to W Janusz.

At least 19 recordsLinked to original sources

PubMed2006

Successive interaction of pairs of soluble organics with nanosilica in aqueous media.

Successive interaction of different pairs of water-soluble polymers (poly(ethylene glycol) (PEG), poly(vinyl pyrrolidone) (PVP), poly(vinyl alcohol) (PVA)), proteins (bovine serum albumin (BSA), ovalbumin, gelatin, and ossein), and smaller organics such as lecithin (1-stearoyl-2-oleoyl phosphatidylcholine, SOPC) and Aethonium (1,2-ethylene-bis(N-dimethyl carbodecyl oxymethyl) ammonium dichloride) with nanosilicas A-300 (S(BET)=232 and 297 m(2) g(-1)) and A-50 (S(BET)=52 m(2)g(-1)) was studied using dynamic light scattering, adsorption, and infrared (FTIR) spectroscopy methods. Time-dependent rearrangement of particle size distributions (PSDs) depicts appearance of both smaller and larger aggregates for silica/PEG(I-first adsorbate)/BSA(II-second adsorbate) and silica/PVP(I)/BSA(II) (i.e., BSA adsorbs onto PEG/silica or PVP/silica) than that for silica/organic compound I. However, in the cases of PVA(I)-BSA(II) and PVA(I)-SOPC(II) a similar effect is not observed because only increased aggregation occurs. The successive equilibrium adsorption of similar pairs shows a diminution of the adsorption of the second compound (gelatin, ovalbumin) with increasing amount of the first adsorbed polymer (PEG or PVP).

Journal Article↗

PubMed2005

Coadsorption of Cd(II) and oxalate ions at the TiO2/electrolyte solution interface.

The study of the adsorptions of cadmium and oxalate ions at the titania/electrolyte interface and the changes of the electrical double layer (edl) structure in this system are presented. The adsorption of cadmium or oxalate ions was calculated from an uptake of their concentration from the solution. The concentration of Cd(II) or oxalate ions in the solution was determined by radiotracer method. For labeling the solution 14C and 115Cd isotopes were used. Coadsorption of Cd(II) and oxalic ions was determined simultaneously. Besides, the main properties of the edl, i.e., surface charge density and zeta potential were determined by potentiometer titration and electrophoresis measurements, respectively. The adsorption of cadmium ions increases with pH increase and shifts with an increase of the initial concentration of Cd(II) ions towards higher pH values. The adsorption process causes an increase of negatively charged sites on anatase and a decrease of the zeta potential with an increase of initial concentration of these ions. The adsorption of oxalate anions at the titania/electrolyte interface proceeds through the exchange with hydroxyl groups. A decrease of pH produces an increase of adsorption of oxalate ions. The processes of anion adsorption lead to increase the number of the positively charged sites at the titania surface. However, specific adsorption of bidenate ligand as oxalate on one surface hydroxyl group may form inner sphere complexes on the metal oxide surface and may overcharge the compact part of the edl. The presence of oxalate ions in the system affects the adsorption of Cd(II) ions on TiO2, increasing the adsorption at low pH range and decreasing the adsorption at high pH range. Using adsorption as a function of pH data, some characteristic parameters of adsorption envelope were calculated.

Journal Article↗

PubMed2005

Morphology and surface properties of fumed silicas.

Several series of fumed silicas and mixed fumed oxides produced and treated under different conditions were studied in gaseous and liquid media using nitrogen and water adsorption-desorption, mass spectrometry, FTIR, NMR, thermally stimulated depolarization current (TSDC), photon correlation spectroscopy (PCS), zeta potential, potentiometric titration, and Auger electron spectroscopy methods. Aggregation of primary particles and adsorption capacity (Vp) decrease and hysteresis loops of nitrogen adsorption-desorption isotherms becomes shorter with decreasing specific surface area (S(BET)). However, the shape of nitrogen adsorption-desorption isotherms can be assigned to the same type independent of S(BET) value. The main maximum of pore size distribution (gaps between primary nonporous particles in aggregates and agglomerates) shifts toward larger pore size and its intensity decreases with decreasing S(BET) value. The water adsorption increases with increasing S(BET) value; however, the opposite effect is observed for the content of surface hydroxyls (in mmol/m2). Associative desorption of water (2(SiOH)-->SiOSi+H2O) depends on both the morphology and synthesis conditions of fumed silica. The silica dissolution rate increases with increasing S(BET) and pH values. However, surface charge density and the modulus of zeta-potential increase with decreasing S(BET) value. The PCS, 1H NMR, and TSDC spectra demonstrate rearrangement of the fumed silica dispersion depending on the S(BET) value and the silica concentration (C(SiO2)) in the aqueous suspensions. A specific state of the dispersion is observed at the C(SiO2) values corresponding to the bulk density of the initial silica powder.

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PubMed2003

Study of interaction of proteins with fumed silica in aqueous suspensions by adsorption and photon correlation spectroscopy methods.

The interaction of fumed silica A-300 (S(BET) = 297 m2 g(-1)) with bovine serum albumin (prepared by different methods), ovalbumin, human hemoglobin, and gelatin as a function of pH, salinity, and concentrations of components in aqueous medium was studied by adsorption and photon correlation spectroscopy (PCS) methods. Comparison of equilibrium (incubation time t(i) approximately 1 h) adsorption of proteins on A-300, minute (t(i) approximately 1 min) flocculation rate, and the particle size distributions measured by the PCS method shows different rearrangement of particle swarms depending on pH, salinity, and concentration of proteins, especially at pH close to IEP of silica or proteins. The electrokinetic mobility of protein/silica swarms is greater than that of individual components at pH far from the IEP of proteins. Changes in the Gibbs free energy (DeltaG) on protein adsorption depend on pH (-DeltaG is minimal at pH 2, close to the IEP of silica, and maximal at pH between the IEP of protein and silica), concentration (-DeltaG is maximal at C(p) between 1 and 6 mg/ml), type of proteins, and their preparation technique.

Journal Article↗

PubMed2002

Characteristics of modified Cab-O-Sil in aqueous media.

Fumed silica Cab-O-Sil HS-5 grafted with 3-aminopropyldimethylsilyl (APDMS), butyldimethylsilyl (BDMS), octadecyldimethylsilyl (ODDMS), and trimethylsilyl (TMS) groups of different concentrations were studied using photon correlation spectroscopy, electrophoresis, potentiometric titration, and nitrogen adsorption methods. Calculations of both electrophoretic mobility and zeta potential were performed taking into consideration the topological structure of "porous" aggregates of primary particles of fumed silica using two different approaches. Changes in surface charge density and the textural, aggregative, and electrophoretic characteristics of modified silicas depend on the type of grafted OSC, its chain length, polarity, and surface concentration. Particle swarms of initial and modified silicas in aqueous suspension are typically characterized by bimodal size distributions between 20 and 300 nm (aggregates) and 1-3 microm (agglomerates of aggregates). The difference between parameter values computed according to the Smoluchowski theory and improved approaches increases with increasing pH and is concordant for both mobility and zeta potential.

Journal Article↗

PubMed2001

[Treatment of intracranial aneurysms during pregnancy].

Aneurysmal subarachnoid hemorrhage (SAH) during pregnancy is rare but serious obstetric complication. SAH occurs more often in primiparae and in the third trimester of pregnancy. The hemodynamic and endocrine changes play an important role in the growth and rupture of aneurysms. There are no differences in the clinical course of SAH among pregnant and non-pregnant patients. Subarachnoid hemorrhage during pregnancy may be confused with eclampsia. The confirmation of the diagnosis is made by computed tomography (CT) or lumbar puncture and cerebral angiography. Ruptured intracranial aneurysms should be treated as they would be in patients who are not pregnant. When the aneurysm is successfully clipped, the pregnancy can be allowed to progress to term. In these cases the vaginal delivery is preferred by most clinicians. Caesarean section would be indicated in several circumstances: when the clinical state of mother is severe (coma, brain stem damage), if the aneurysm is diagnosed at term of labour, if the interval between the neurosurgical treatment of aneurysm and labour is less than 8 days.

Adult↗

PubMed2000

Highly Dispersed X/SiO(2) and C/X/SiO(2) (X=Alumina, Titania, Alumina/Titania) in the Gas and Liquid Media.

Fumed oxides, such as silica, alumina, titania, and mixed X/silicas (X=Al(2)O(3) (AS), TiO(2) (TS), CVD-TiO(2), Al(2)O(3)/TiO(2) (AST)), pristine or covered by carbon deposits formed due to pyrolysis of cyclohexene, were studied using nitrogen adsorption-desorption, photon correlation spectroscopy particle sizing, and electrophoresis. A significant influence of the nature of surface-active sites and structural features of oxides (individual silica, mixed fumed, or prepared using chemical vapor deposition (CVD)) on the pyrolysis of cyclohexene is observed with respect to the pore size distributions due to differences between primary particles in aggregates and on their outer surfaces in the filling of channels by pyrocarbon, resulting also in a decrease in fractal dimension. Structural characteristics and dependences of the particle size distribution and electrokinetic potential of X/SiO(2) and C/X/SiO(2) on the pH of aqueous suspensions suggest that the carbon deposit covers mainly acidic sites at the X/SiO(2) interfaces and X phase patches possessing catalytic activity in pyrolysis, as the negative charge of particles is reduced by pyrocarbon grafting. Copyright 2000 Academic Press.

Journal Article↗

PubMed1997

Investigation of the Electrical Double Layer in a Metal Oxide/Monovalent Electrolyte Solution System

Adsorption of the monovalent cations Cs+ and Na+ from mixed solutions of NaCl and CsCl at the TiO2(anatase)/water interface was studied. Higher adsorption of Cs+ than Na+ was observed from solutions of similar electrolyte concentration. The surface ionization and complexation constants of surface hydroxyl groups were determined using potentiometric titration data. Results for the adsorption of Cs+ and Na+ from mixed electrolyte solutions showed that these ions adsorb at different distances from the metal oxide surface.

Journal Article↗

PubMed1992

Influence of flunarizine, nicardipine and nimodipine on the anticonvulsant activity of different antiepileptic drugs in mice.

Only flunarizine (40 mg/kg, i.p.) significantly raised the threshold for electroconvulsions in mice (ear-clip electrodes, 0.2 sec stimulus duration, tonic hindlimb extension as an endpoint), whilst nicardipine and nimodipine (up to 80 mg/kg) was ineffective in this respect. Further, flunarizine (10 and 20 mg/kg) potentiated the efficacy of carbamazepine and valproate against maximum electroshock (50 mA)-induced seizures and, in the dose of 20 mg/kg, enhanced that of diphenylhydantoin. In addition, this calcium channel inhibitor was without influence upon the total levels of these antiepileptics in plasma. Nicardipine (5 and 10 mg/kg) and nimodipine (10 and 20 mg/kg) increased the protective potential of carbamazepine and nimodipine (20 mg/kg) also decreased the ED50 of diphenylhydantoin against maximum electroshock. However, nicardipine distinctly increased the level of carbamazepine in plasma, whilst nimodipine did not affect the level of both antiepileptics in plasma. The combined treatment of calcium channel inhibitors and antiepileptic drugs, providing a 50% protection against maximum electroshock, did not significantly change the motor performance of mice in the chimney test, when compared with antiepileptic drugs, given alone at their ED50s, against maximum electroshock-induced convulsions. The present results give further support to the idea of the combined use of some calcium channel inhibitors and antiepileptic drugs in the treatment of human epilepsy.

Animals↗

PubMed1991

Influence of CGS 15943 A (a nonxanthine adenosine antagonist) on the protection offered by a variety of antiepileptic drugs against maximal electroshock-induced seizures in mice.

CGS 15943 A (a nonxanthine adenosine antagonist) was studied on the protective efficacy of carbamazepine (60 min prior to the convulsive test), diazepam (60 min), diphenylhydantoin (120 min), phenobarbital (120 min), and valproate (30 min) against maximal electroshock-induced convulsions in mice. Moreover, the influence of the adenosine antagonist on 2-chloroadenosine (1 mg/kg, 20 min prior to the test)- and valproate (250 mg/kg, 30 min)-induced inhibitions of locomotor activity was also studied. CGS 15943 A (1 mg/kg) was given 15 min before both tests and all the drugs were administered i.p.. The adenosine antagonist (1 mg/kg) remained without influence upon the protective activity of all studied antiepileptics, reflected by their respective ED50 values against maximal electroshock. However, both 2-chloroadenosine and valproate-induced inhibitions of locomotor activity were attenuated by CGS 15943 A, which alone did not affect this parameter. However, CGS 15943 A (5 mg/kg) diminished the protection offered by diphenylhydantoin, increasing its ED50 value from 13 to 16 mg/kg. It may be concluded that the protection provided by common antiepileptic drugs against electroconvulsions seems independent of adenosine-mediated inhibition. In the case of diphenylhydantoin, one may suggest the involvement of purinergic transmission in the final anticonvulsant effect.

Adenosine↗

PubMed1990

Differential effects of agents enhancing purinergic transmission upon the antielectroshock efficacy of carbamazepine, diphenylhydantoin, diazepam, phenobarbital, and valproate in mice.

L-phenylisopropyladenosine (L-PIA; a preferential A1 adenosine agonist-0.05 mg/kg) offered no protection against electroconvulsions in mice but potentiated the anticonvulsant action of diazepam and valproate against maximal electroshock-induced seizures, decreasing the respective ED50 values from 9.5 to 4.0 mg/kg and from 250 to 185 mg/kg. However, it remained without effect on the protective activity of phenobarbital, carbamazepine and diphenylhydantoin. 5'-N-ethylcarboxamidoadenosine (NECA; a preferential A2 adenosine agonist-0.5 mg/kg) potentiated the efficacy of valproate. On the other hand, NECA (1 mg/kg) diminished the anticonvulsant action of phenobarbital (ED50 was elevated from 16.5 to 20.5 mg/kg), possessing no effect upon the protective action of carbamazepine. In addition, papaverine (20 mg/kg) significantly enhanced the protective efficacy of valproate and up to 40 mg/kg remained without influence upon the protective action of carbamazepine. However, papaverine (20 and 40 mg/kg) inhibited the anticonvulsive potential of phenobarbital. In the light of the results obtained A1 and A2 adenosine receptor-mediated events seem to possess different influences upon the protective effects of antiepileptic drugs.

Adenosine↗

PubMed1989

Effect of aminophylline upon the protective activity of common antiepileptic drugs and their plasma levels in mice.

Aminophylline (50 mg/kg) decreased the protective efficacy of carbamazepine (20 mg/kg), diphenylhydantoin (8-12 mg/kg), phenobarbital (20 and 25 mg/kg), and valproate (250 and 300 mg/kg) against electroconvulsions in mice. On the other hand, aminophylline (5 mg/kg) was devoid of such activity. Plasma levels of antiepileptic drugs were measured with the help of the Abbott TDx analyzer and after administration of carbamazepine (20 mg/kg), diphenylhydantoin (10 mg/kg), phenobarbital (25 mg/kg), and valproate (250 mg/kg) were as follows: 8.61, 6.48, 24.3 and 329 micrograms/ml, respectively. Aminophylline (50 mg/kg) remained without any significant influence upon these plasma levels. This may lead to the conclusion that aminophylline-induced reversal of antiepileptic drug activity is not dependent upon a pharmacokinetic mechanism and probably occurs at the neuronal level.

Aminophylline↗

PubMed1989

The role of the central serotonergic system in pilocarpine-induced seizures: receptor mechanisms.

Modification of central serotonergic transmission resulted in alterations of pilocarpine convulsive activity in male Wistar rats. Seizure activity was increased after pizotifen injection and the latency period to onset of convulsions was shortened in animals pretreated with mianserine and quipazine. Stimulation of 5-HT1A receptors with 8-hydroxy-di-N,N-propylaminotetralin (8-OH-DPAT) and blockade of 5-HT1B receptors with cyanopindolol resulted in seizure protection. Intracerebroventricular injections of 5,6-dihydroxytryptamine (5,6-DHT) did not change the protective effect of cyanopindolol. Other agents specifically affecting serotonergic receptors, the agonists 1-(3-chlorophenyl)piperazine (mCPP) and 5-methoxytryptamine (5-MT) and the antagonists spiperone, metergoline, methysergide, cyproheptadine and metoclopramide, did not influence pilocarpine-induced seizures. In conclusion, the present study suggests that the inhibition of pilocarpine-induced seizures may be mediated by stimulation of 5-HT1A and by blockade of 5-HT1B receptors, located probably on the cholinergic terminals.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed1987

Inhibition of aminophylline-induced convulsions in mice by antiepileptic drugs and other agents.

Common antiepileptic drugs and agents affecting different neurotransmitter systems were studied against aminophylline (280 mg/kg i.p.)-induced convulsions in mice. All drugs and agents were administered i.p. Diazepam and phenobarbital antagonized the whole seizure pattern and the respective ED50 values for the clonic phase were 3.5 and 62 mg/kg. Valproate at 500 mg/kg protected fewer than 50% of mice against the clonic phase. The remaining antiepileptics (acetazolamide, up to 1,000 mg/kg; carbamazepine and diphenylhydantoin, up to 50 mg/kg; ethosuximide, 500 mg/kg and trimethadione, 400 mg/kg) were totally ineffective in this respect. Propranolol (up to 20 mg/kg), baclofen (20 mg/kg), gamma-hydroxybutyric acid (300 mg/kg), aminooxyacetic acid (20 mg/kg), clonidine (up to 0.2 mg/kg), ketamine (30 mg/kg), atropine (20 mg/kg), papaverine (50 mg/kg) and L-phenylisopropyladenosine (2 mg/kg) did not affect the clonic phase either. Only antagonists of N-methyl-D-aspartic acid excitation, 2-amino-5-phosphonopentanoic acid and 2-amino-7-phosphonoheptanoic acid afforded protection against aminophylline-induced clonic seizure activity. The results show that aminophylline convulsions are relatively resistant to antiepileptic drugs and suggest that antagonists of excitatory transmission are potential antiaminophylline drugs.

2-Amino-5-phosphonovalerate↗

PubMed1976

Quantitative electrocardiography during extended space flight: the second manned Skylab mission.

To assess the effects of space flight on cardiac electrical properties, vectorcardiograms (VCG) were obtained on the Skylab crew at regular intervals during the 59-d flight (SL3) and during the pre- and postflight periods. The Frank lead system was used and observations were made at rest; during 25%, 50%, and 75% of maximum exercise; during a short pulse of exercise (150 W, 2 min); and after exercise. Data from 47 in-flight tests were analyzed by computer and compared to preflight and postflight values. A statistically significant increase in QRS maximum vector magnitude (all SL3 crewman); and an increase in resting PR interval (all SL3 crewmen) occurred. During exercise, the PR interval did not differ from preflight. Exercise heart rates in flight were same as preflight, but increased in the immediate postflight period. No major changes in QRS, T, or ST vector direction occurred. The scientist pilot had premature ventricular beats sporadically during the flight. This astronaut also had intermittent periods of atrioventricular junctional rhythm throughout the flight. The increase in QRS maximum vector magnitude resembles the electrocardiographic changes associated with athletic conditioning and may be related to increased ventricular volume secondary to centripetal shifts of fluid and/or the in-flight isotonic exercise program. Prolongation of the PR interval at rest with normalization of exercise suggests that there was increased vagal tone or suppressed sympathetic influence during the flight.

Adult↗

PubMedDate not supplied

Influence of different methylxanthines on the anticonvulsant action of common antiepileptic drugs in mice.

The protective activity of carbamazepine (CBZ, 60 min before testing), phenobarbital (PB, 120 min), phenytoin (PHT, 120 min), and valproate (VPA, 30 min) alone or concurrent with methylxanthine derivatives was evaluated against maximal electroshock-induced seizures (MES) in male mice. All drugs were administered intraperitoneally (i.p.), and the protection offered by antiepileptic drugs (AEDs) was expressed as ED50 in mg/kg. Caffeine sodium benzoate in doses of 0.0595-0.476 mmol/kg (11.55-92.4 mg/kg) distinctly reduced the anticonvulsant efficacy of PB, in the highest dose tested with an increase in ED50 value from 19.5 to 38 mg/kg. This methylxanthine derivative in the dose range of 0.119-0.476 mmol/kg (23.1-92.4 mg/kg) also efficiently inhibited the protective action of PHT. When combined with caffeine (0.238 and 0.476 mmol/kg), the ED50 of PHT was raised from 12 to 17 and 24 mg/kg, respectively. In doses of 0.238 and 0.476 mmol/kg, caffeine also diminished the efficacy of CBZ and VPA, and at the highest dose tested the methylxanthine elevated the respective ED50s from 13 to 20.5 mg/kg and from 270 to 420 mg/kg. Generally caffeine sodium benzoate (up to 0.476 mmol/kg) did not affect the plasma levels of studied AEDs, and only at 0.476 mmol/kg did it significantly decrease the level of PHT. Among the other methylxanthines, pentoxifylline (0.238-0.476 mmol/kg; 66.3-132.5 mg/kg) and diprophylline (0.952 mmol/kg; 242.1 mg/kg) inhibited the protective potential of PHT and the respective ED50s were raised from 12 to 16.5, 15.5, and 14 mg/kg. No significant alterations in PHT plasma levels were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

[Metastatic tumors in vertebral canal].

Medical records of patients suffering from spinal cord or cauda equina compression secondary to metastatic tumour of the spinal canal were reviewed. Out of 55 patients treated in the Department of Neurosurgery in Lublin throughout 1976-1996 for metastatic disease of the spinal canal, forty were operated on. Clinical symptoms, methods of treatment and course of disease in this last group of patients were analysed. It showed that the great majority of patients are admitted to the neurosurgical department with severe neurological deficits. Eighty percent of patients (n = 40) presented with deterioration of gait and 67.5% had retention of urine, 72.5% had sphincter disturbances. The series comprised patients with carcinoma of the lung (22.5%), kidney (7.5%), prostate (7.5%), neoplastic disease of the lymphatic system (12.5%) and other malignant neoplasm accounting for 62.5%. As a general rule, decompressive laminectomy was carried out. Surgery was usually performed as an emergency in order to arrest progression of neurological deficits and to prevent irreversible damage to the roots and spinal cord. The tumours were usually extradural, located in the lower part of the thoracic spine and invading surrounding tissues, including bone. Histological diagnosis of spinal tumour as a metastasis preceded diagnosis of a primary tumour, but in 1/3 of cases histology could not indicate of the primary malignancy. There are substantial differences in the clinical course of a metastasis in the thoracic and lumbosacral spine. Own experience indicates that surgery of spinal metastases in patients with severe neurological deficits has a very limited effectiveness.

Adult↗

PubMedDate not supplied

Synthesis and some central pharmacological properties of new derivatives of 2,3-dihydroimidazo[1,2-a]pyrimidine-6-carboxylic acid.

Twenty one derivatives of 2,3-dihydroimidazo[1,2-a]pyrimidine-6-carboxylic acid (6 n-butyl amides and 15 free acids) bearing the aromatic ring in position 1 or 2 were obtained. They were synthesized by aminolysis or hydrolysis of respective ethyl esters. Pharmacological studies on the central action of eight compounds 1, 2, 4, 5, 7, 8, 9 and 10 were carried out on mice and rats. The most active compounds, producing sedation and hypothermia, and 1, 2 and 5. The compounds decreased amphetamine-induced hyperactivity. Besides, compound 2 exerted analgesic effect in mice.

Animals↗