Numerical profile correction of microwave cavity resonance spectroscopy measurements of the electron density in low-pressure discharges.

Low-temperature plasmas are widely studied in laboratory environments and form the backbone of many industrial processes. Highly energized electrons enable processes such as ionization, dissociation, and plasma chemical reactions, while the heavy species, such as neutral gas atoms and molecules, remain near room temperature. Hence, understanding the electron dynamics is crucial to the control and optimization of plasmas and their applications. In this contribution, we investigated the impact of electron density profile correction on microwave cavity resonance spectroscopy (MCRS) as a diagnostic tool for low-pressure discharges. Following standard practice, we first obtained a volume-averaged electron density by assuming a uniform plasma in the interpretation of the MCRS diagnostic technique. Second, we compare the experiments with a numerical model solved using PLASIMO software to evaluate the predictive capabilities. Third, we obtained profile-corrected electron densities by means of incorporating the numerically obtained distribution of the electron density and the numerical solution for the resonant microwave electric field in the interpretation of the experimental data using MCRS. Although the volume-averaged data agree closely with the electron density found from the numerical model, it is shown that implementing the spatial distribution of the electron density and the microwave electric field leads to a significant correction to the experimental data. The developed strategy could easily be implemented in other situations deploying MCRS as a non-invasive technique for measuring the electron density.

Lupus-specific kidney deposits of HSP90 are associated with altered IgG idiotypic interactions of anti-HSP90 autoantibodies.

Previous studies have shown that autoantibodies to heat shock protein 90 (HSP90) are elevated in a significant proportion of patients with systemic lupus erythematosus (SLE) who are more likely to have renal disease and a low C3 level. Using samples from 24 patients, we searched for glomerular deposits of HSP90 in renal biopsy specimens from seven patients with lupus nephritis and 17 cases of glomerulonephritis from patients without SLE. Positive glomerular immunofluorescent staining for HSP90 was observed in six of seven cases of SLE and positive tubular staining in two of seven SLE patients. The staining for HSP90 was granular in nature and was located in subepithelial, subendothelial and mesangial areas. None of the non-SLE renal biopsies revealed positive staining for HSP90 deposition. Further we showed the presence of anti-HSP90 IgG autoantibodies in IgG from sera of patients with SLE as well as in normal human IgG (IVIg). In normal IgG this autoreactivity could be adsorbed almost completely on F(ab')2 fragments from the same IgG preparation, coupled to Sepharose and could be inhibited by the effluent obtained after subjecting normal IgG to HSP90 affinity column. These findings indicate that anti-HSP90 natural autoantibodies are blocked by idiotypic interactions within the IgG repertoire. Unlike natural autoantibodies, anti-HSP90 IgG from SLE patients' sera were only moderately adsorbed on F(ab')2 fragments of normal IgG. These results demonstrate that immunopathogenesis of lupus nephritis is associated with HSP90 (as an autoantigen) and that the pathology is associated with altered idiotypic regulation of the anti-HSP90 IgG autoantibodies.

Autoimmune thyroid disorders in juvenile chronic arthritis and systemic lupus erythematosus.

The appearance of autoimmune thyroiditis in the course of other autoimmune diseases, which do not affect specific organs (systemic lupus erythematosus, Sjögren syndrome, rheumatoid arthritis and others), is more frequent than is usually believed. Nevertheless, it is scarcely studied, especially in children. The purpose of this study was to look for autoimmune lesions of the thyroid gland in children suffering from juvenile chronic arthritis (JCA) and systemic lupus erythematosus (SLE). Twenty seven children having JCA and twelve children with SLE, aged 5 to 18 years, were enrolled into study. In all of them the disease was in an active phase. The serum levels of total thyroid hormones (T3, T4) and TSH, thyroid antibodies (TAB and MAB) and antinuclear antibodies (ANAB) were analyzed using respectively fluoroimmunologic, microhemagglutination and indirect immunofluorescention tests. According to our results, autoimmune thyroiditis was found in 12 out of 27 children with JCA (44.4%); 85.2% of them were euthyroid, 11.1% had a compensated hypothyroidism, and 3.7% had Hashi-toxicosis. From a clinical point of view, very interesting was the combination of JCA, autoimmune thyroiditis and pseudoxanthoma elasticum in a 13-year old girl. Positive thyroglobulin antibodies (1:80-1:5120) were found in 17 out of 27 cases of JCA (63%). The microsomal antibodies were elevated (1:100-1:1600) in 7 out of 27 (25.9%); antinuclear antibodies (1:80-1:640) were detected in 15 out of 27 cases of JCA (55.5%). A simultaneous elevation of all three kinds of antibodies was found in 14.8% of children with JCA, and of TAB and MAB--in 18.5%. Thyroid gland disorders were detected also in children suffering from SLE. Thyroglobulin antibodies were positive (1:80-1:5120) in 7 out of 12 cases. Antinuclear antibodies (1:320-1:2560) were detected in 8 out of 12 cases (66.7%). The serum levels of T3, T4 and TSH were in the reference limits in all children with SLE. The present study suggests that involvement of the thyroid gland is not uncommon in autoimmune disease in Autoimmune thyroiditis can occur in association with other autoimmune diseases, affecting some organs or systems, such as the insulin-dependent diabetes mellitus, pernicious anaemia, thrombocytopenia, vitiligo, as well as some chromosomal aberrations--Turner's syndrome, Noonan's syndrome and Down's disease [1]. The appearance of autoimmune thyroiditis together with other autoimmune diseases which do not affect specific organs (such as systemic lupus erythematosus, Sjögren syndrome) is the reason to classify them in a common subgroup of the autoimmune polyendocrine syndromes--type IIID [2]. The rheumatic diseases are--more frequently than suspected--associated with autoimmune thyroiditis, but this connection is not well studied. The literature offers very scarce information on the problem, especially for the childhood. The purpose of this study was to look for autoimmune lesions of the thyroid gland in children suffering from juvenile chronic arthritis (JCA) and systemic lupus erythematosus (SLE).

Prevalence of IgM-, IgA- and IgG-rheumatoid factors in seronegative polyarticular disease compared to pauciarticular disease in juvenile chronic arthritis as measured by ELISA.

OBJECTIVE: To determine the prevalence of the rheumatoid factor isotypes measured by enzyme-linked immunosorbent assay (ELISA) in polyarticular and pauciarticular juvenile chronic arthritis (JCA), and evaluate the diagnostic test qualities. PATIENTS AND METHODS: 53 patients with JCA (20 with seronegative polyarticular disease at onset, 21 with pauciarticular onset and course of disease and 12 with extended pauciarticular disease), as well as 125 control children (58 healthy controls and 67 patients with other diseases) were tested. ELISA for the detection of IgM-, IgA- and IgG-isotypes of RFs was used. The diagnostic characteristics of the tests were evaluated by means of clinical epidemiology methods. RESULTS: The prevalence of the ELISA for IgG-, IgA-, and IgM-RF for JCA patients vs all controls at optimal cut-off titres was 13%, 29%, and 32%, respectively. The test for IgG-RF was established to be of no significance. IgA-RF had higher prevalence in the polyarticular and extended pauciarticular form, 40% and 33%, respectively. IgM-RF showed a prevalence of 55% for the polyarticular and 42% for the extended pauciarticular form. No significant prevalence has been found in the pauciarticular form. CONCLUSION: Our results indicate that ELISA for IgG-RF is of no diagnostic value for JCA. The ELISAs for IgM- and IgA-RFs demonstrated a diagnostic significance for the polyarticular and extended pauciarticular form. Juvenile chronic arthritis (JCA) is a heterogeneous disease which encompasses different forms defined by the type of onset. There is evidence, supported by immunogenetic studies that the various subgroups may represent distinct disease entities [1, 2]. Numerous immunological abnormalities have been detected in JCA, but the most characteristic serological findings are ANA and IgM-rheumatoid factor, thought to be useful in the classification of patients and their management. Antinuclear antibodies are universal in JCA, most commonly found in children with early onset pauciarthritis and late onset seropositive polyarthritis [1, 2, 3]. In contrast, the IgM-rheumatoid factor, measured by conventional agglutination techniques, is a hallmark only of polyarthritis with late onset resembling adult rheumatoid arthritis. This group of patients with "seropositive" disease represents less than 20% of all JCA children. Of those patients with "seronegative" disease 20-30% have a systemic onset and the remainder have either a pauciarticular or polyarticular form [2, 3]. Following the introduction of more sensitive techniques, it has already been established that rheumatoid arthritis (RA) patients' sera contain not only the "classical" 19S IgM-RF, but also other isotypes of the rheumatoid factor (RF). A number of studies have emphasized the presence of IgG-, IgA-, IgM- and even IgE- RF in patients with "seronegative" RA [4, 5, 6]. The aim of this study is to determine the prevalence of IgG, IgM and IgA RFs and to attempt at evaluating the diagnostic and prognostic qualities of the ELISA-tests for rheumatoid factor isotypes in polyarticular and pauciarticular forms at onset of JCA.

Binding of phenylbutazone to human serum albumin. Characterization and identification of binding sites.

The quantitative parameters characterizing the binding of phenylbutazone (CAS 50-33-9) to human serum albumin are determined using the circular dichroism titration method and a combined mathematical approach. The values of affinity constants obtained are in good agreement with those found in the literature. The characterization and identification of binding sites is also performed. A conclusion is derived that phenylbutazone can be used as a model compound for investigation of ligand-macromolecule interactions.

Modelling of indometacin and diclofenac sodium binding to the molecule of human serum albumin.

Modelling of the binding of two non-steroidal anti-inflammatory drugs, indometacin (CAS 53-86-1) and diclofenac sodium (CAS 15307-79-6) to the molecule of human serum albumin is presented. The models are based on the data obtained using difference spectroscopic technique. Speculations were made concerning the structural properties of the drugs and albumin molecules as well as the type of chemical interactions taking part in the drug-albumin binding. The proposed approach represents a more detailed investigation on the mechanism of drug-protein interactions.

Binding of ketoprofen to human serum albumin studied by circular dichroism.

The protein binding of ketoprofen has been studied using circular dichroism titration method as well as the new algorithm proposed by the authors for the treatment of data obtained. The quantitative parameters association constants (k) and number of binding sites (N) have been determined. It is proved that the protein binding of Ketoprofen is going through separate stages and the number of binding sites probably arises. It is acceptable that a high affinity binding takes place primarily (kI = 3.8 x 10(6) l.mol-1). Later, due to the conformational changes in the protein molecule the binding areas are modified and the number of binding sites considerably arises (NI = 3.5 and NII = 14), while the binding affinity reduces 100-fold (kII = 5.10(4) l.mol-1). The number of binding sites has been studied and an identification of the chromophore taking part in the drug-protein interaction has been performed on the base of UV- and CD spectra. A mechanism of the interaction is proposed which coincides with the stepwise binding model.

Comparative effects of the anticholinesterase drug galanthamine on the mechanical activity of isolated rat jejunum and ileum.

1. The effects of cumulatively applied galanthamine hydrobromide (0.1-300 microM) on the mechanical activity of isolated proximal jejunum and distal ileum were studied. 2. Galanthamine was found to increase the spontaneous mechanical activity and exert by itself an enhancement of the smooth muscle tone in the two segments, both effects being more pronounced in ileum than in jejunum. 3. The galanthamine-induced augmentation of the spontaneous mechanical activity was tetrodotoxin (TTX)-sensitive, whereas the contractile effect of the drug on the tone was TTX-insensitive in both segments. 4. The present results showed not only quantitative differences in the tonic effects of galanthamine in both intestinal segments but they suggest some qualitative differences in cholinergic neuronal control along the gastro-intestinal tract.

Gastrointestinal loss of galanthamine hydrobromide in rats in-situ.

The disappearance kinetics of the acetylcholinesterase inhibitor galanthamine hydrobromide from the gastrointestinal tract of male Wistar rats, 200-250 g, in-situ has been examined. After 30 min the galanthamine loss was 16% in the stomach (pH 2), 54-85% in the duodenum and the successive small intestinal segments (pH 6.8), 43% in the colon and 76% in the rectum. Compared with the other segments, the disappearance rate was higher in the terminal ileum (0.38 x 10(-2) mg cm-1 min) and in the rectum (1.27 x 10(-2) mg cm-1 min). In the proximal jejunum, terminal ileum and rectum the disappearance rate was linearly dependent on the galanthamine dose (range 0.5-4 mg, 2-16 mg kg-1). The results suggest that when administered orally, rapid galanthamine absorption could be expected all over the gastrointestinal tract due mainly to the passive diffusion mechanism.

Pharmacokinetics of galanthamine hydrobromide after single subcutaneous and oral dosage in humans.

Galanthamine hydrobromide (Nivalin, dose 10 mg) was given subcutaneously and orally to 8 volunteers. Galanthamine and its metabolites were quantified in plasma and urine by reversed-phase HPLC. An unusual two-stage absorption and biexponential drug decline were observed. Galanthamine plasma peaks (1.24 micrograms/ml after subcutaneous and 1.15 micrograms/ml after oral doses) were reached 2 h following administration, the t1/2(beta) values being 5.70 and 5.26 h, respectively. Minor epigalanthamine and galanthaminone plasma levels were detected. An almost complete urinary recovery of galanthamine and its metabolites was obtained within 72 h. The plasma AUC, Cmax, tmax and ka suggest that the subcutaneous and oral Nivalin formulations are bioequivalent.

Pharmacokinetics of vephylline--a new N-substituted theophylline derivative.

Vephylline (7,2-bis-2-hydroxyethylamino-1, 3-dimethylxanthine tartarate) is a xanthine derivative with high bronchodilating activity, low toxicity, and weak effects on the central nervous system. The aim of this study is to determine the pharmacokinetic parameters of vephylline after intravenous and oral (in solution and in tablets) administration to rabbits. Vephylline (dose 50 mg/kg b.w. intravenousely and orally in solution and dose 53.5 mg/kg b.w. in the form of tablets) is administered to the rabbits in an autocontrol crossover design at 7-days intervals. After the intravenous administration the distribution is relatively fast (t1/2 alpha = 3.28h). High values of the apparent volume of distribution--12.15 1/kg suggest tissue accumulation. Elimination is considerably slower (t1/2 beta = 19,00 h) than distribution. After oral administration of the drug in solution the absorption half-life is short and the bioavailability is relatively high. Peak plasma levels are attained at the first hour. The differences in the distribution and elimination patterns for vephylline and theophyline could determine a longer effect for the new bronchodilating drug. The results are discussed in regard to the future clinical application of vephylline.

In vitro metabolism of galanthamine hydrobromide (Nivalin) by rat and rabbit liver homogenate.

The metabolism of galanthamine hydrobromide (Nivalin) was investigated in rat and rabbit liver homogenates. Experiments were carried out varying several parameters of incubation: substrate (galanthamine hydrobromide, galanthamine, galanthaminone and epigalanthamine), cofactor enrichment (NADPH, NADP/G-6-P, NAD), pH (7.4 and 9.3), time of incubation. Substrates and metabolites were identified and quantitatively determined by GC/MS. In vitro metabolism in rat liver homogenate was negligible. The experiments with rabbit liver homogenate indicated, that galanthamine was actively metabolised the major metabolites being the oxidised product - galanthaminone, and the isomer of galanthamine - epigalantamine. The experimental results show that the metabolism of galanthamine is substrate and product stereoselective.

Pharmacokinetics of galanthamine hydrobromide (Nivalin) following single intravenous and oral administration in rats.

A study on galanthamine hydrobromide (Nivalin) pharmacokinetics was carried out on male Wistar rats following single intravenous and oral administration. Plasma samples were collected after decapitation of the animals. The drug concentrations were determined spectrophotofluorometrically. A two-compartment open model was found to describe best the experimental data. Galanthamine has an elimination half-life of 40-50 min, a volume of distribution over 2 liters/kg, a plasma clearance of about 2 liters/h X kg and an oral bioavailability of about 65%.

Modeling of pharmacokinetic and pharmacodynamic behavior of nivalin in anaesthetized cats.

The pharmacokinetic behaviour of nivalin (galanthamine hydrobromide) and its effect on the contractile response of electrically stimulated m. tibialis anterior were simultaneously studied after an i.v. administered dose of 3 mg/kg in cats. The determination of some basic pharmacokinetic parameters revealed that nivalin was distributed in a large volume (Vss = 2.17L/kg) and was quickly eliminated (t0.5 of elimination was 1.7 h), the area under the plasma concentration-time curve (AUC was 5.93 micrograms . h/ml and the total clearance (CL) - 1.05 L/h . kg. The pharmacological effect appeared almost instantly after nivalin administration, went through a maximum and slowly decreased for a period of 1.5-2 hours. Linear and logarithmic-logistic functions were used to detect the correlation between the pharmacokinetic and the pharmacodynamic data. The calculated correlation coefficients showed that the linear function better described the relationship between plasma concentrations and tibial muscle contractile response than the logarithmic-logistic function. In comparison with the classical anticholinesterase drugs nivalin showed some advantages concerning its pharmacokinetics, namely the prolonged residence in the cat's body and, as a result, a longer-lasting pharmacological effect.

Correlations between the pharmacological effects and the pharmacokinetic behaviour of tetraminol.

Tetraminol (trans-2-hydroxyethylamino-3-hydroxy-5,8-dimethoxy-1,2,3, 4-tetrahydronaphthalene hydrochloride) is a newly synthesized antihypotensive agent. Its pressor activity is accompanied by a compensatory slowing down of heart rate. Changes in plasma levels after intravenous administration of 1 and 2 mg/kg b.w. to rats and rabbits can be fitted to a two-compartment open pharmacokinetic model (previous communications). Experiments were carried out with simultaneous registration of effects on blood pressure (R1) and heart rate (R2). Mathematical treatment of data for R1 and R2 revealed that changes with time can be described by biexponential equations of the type: R1i = A1i.e-a1it+B1i..e-a21t. Three different ways to correlate the data from the pharmacological and pharmacokinetic experiments were tried: 1) For the time interval during which the pharmacological response changes in the range Rimax- 20 to Rimax- 80% there exists a linear relationship with a high degree of statistical significance between the changes in the effects and plasma levels. 2) In the lambda 1-phase of the drug distribution there also exists a linear relationship between the effects and plasma levels. This is so because Tetraminol exhibits its pressor effect by direct stimulation of alpha-adrenergic receptors in the walls of the peripheral blood vessels. 3) Most suitable for expressing the relationship which exists between the pharmacological effects and the plasma concentration of Tetraminol for the entire time interval is the nonlinear function of the type: Ri/(Rimax - Ri) = QiCsi.

Quantum mechanical conformational analysis of heterocyclic analogues of norephedrine.

Studies on the conformation of several structural analogues of norephedrine, thiophene, carbazole and furan, were carried out using the differential PCILO method. The erythro-forms of these compounds possess minima on the conformation map corresponding to a gauche conformation with synclinal H-atoms. This result is in good agreement with the proton-proton coupling constants found in previous NMR-studies. H-NMR-studies suggest for the threo-isomers of the studied molecules an equilibrium between the trans- and gache-conformations of the ethanolamine chain. Present calculations agree fairly well with this result. All the studied molecules possess conformational minima corresponding to the folded form of the side chain believed responsible for the physiological activity of norephedrine. The distances between "N" and 'O' atoms in this preferred conformation correspond to the model proposed by Kier and Pullman for alpha-adrenergic receptors.

An ab initio study of electronic factors in metabolic hydroxylation of aliphatic carbon atoms.

The monooxygenase-mediated hydroxylations of aliphatic carbon atoms are known to be regioselective for positions alpha to heteroatoms or to pi systems (aromatic rings, carbon-carbon double bonds, carbonyl groups). Ab initio calculations (STO-3G and in some cases 4-31G) were performed on model molecules, indicating that the Mulliken overlap populations (taken as indices of electron bond densities) of Calpha-H bonds being regioselectively hydroxylated are larger than Cbeta-H and Cgamma-H overlap populations. These results support the hypothesis that metabolic C-hydroxylations occur by insertion of an activated oxygen species of electrophilic nature, probably oxene.

Release of highly soluble substances from inert matrices in cases of two-sided attack of the solvent.

The present work is an extension of some of our earlier investigations on the release of soluble substances in inert matrices. There have been described the cases of two-sided attack on the inert matrices (PVC and PE) by the solvent. The theoretical considerations of the cases for the two-sided attack were experimentally confirmed. The values of the diffusion coefficients, which correspond to the calculated ones in the cases of one-sided attack, were calculated as well.