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Biomedical subjects

L Nováková

Publications and source records attributed to L Nováková.

15 recordsLinked to original sources
PubMed2006

HPLC determination of chlorhexidine gluconate and p-chloroaniline in topical ointment.

A novel fast isocratic reversed-phase HPLC method for simultaneous determination of chlorhexidine and its degradation product p-chloroaniline was developed. Zorbax SB Phenyl column (75 mm x 4.6 mm, 3.5 microm) was used for the separation. Mobile phase composed of acetonitrile and buffer solution of 0.08 M sodium phosphate monobasic containing 5 ml of triethylamine (0.5%) and adjust with 85% phosphoric acid to pH 3.0 in ratio 35:65 (v/v) pumped isocratically at flow rate 0.6 ml min(-1) was used. UV detection was performed at 239 nm, the total analysis time was about 10 min. The method is suitable for practical routine analysis of topical ointment in the quality control laboratory.

Acetonitriles↗
PubMed2006

HPLC determination of calcium pantothenate and two preservatives in topical cream.

A RP-HPLC method for simultaneous determination of calcium pantothenate and two preservatives methylparaben and propylparaben present in topical cream was developed. Different analytical columns with various stationary phases were tested. During method development, Supelco Discovery C18 column (125 mmx4.0 mm, 5 microm) and Zorbax SB-CN column (150 mmx4.6 mm, 5 microm) were tested. Both were not convenient for analytical separation because of the co-elution of calcium pantothenate with dead volume, and problems with the peak-shape of all components. Good separation was achieved using Zorbax TSM (250 mmx4.6 mm, 5 microm) and Hypersil ODS column (250 mmx4.6 mm, 5 microm), the latter was finally used for the analysis. The analysis time was 12 min, at flow rate 0.7 ml min-1. Chromatography was performed using binary mobile phase composed of methanol and phosphoric acid, pH 2.5, 65:35 (v/v). UV detection was accomplished at 214 nm. The method was validated according to ICH guideline recommendations. The method is suitable for practical routine analysis of commercially produced topical pharmaceutical preparations.

Administration, Topical↗
PubMed2005

Development and validation of HPLC method for determination of indomethacin and its two degradation products in topical gel.

Indomethacin forms by decomposition two degradation products: 4-chlorobenzoic acid and 5-methoxy-2-methylindoleacetic acid. They have to be monitored together with an active substance both during manufacturing process and storage of pharmaceuticals. European Pharmacopoeia (Ph. Eur. 4) describes titration method for determination of indomethacin, which is not very convenient in this case for practical use. Therefore, high performance liquid chromatography is the method-of-choice enabling determination of active substance and its degradation products during one-step procedure simultaneously and automatically. We have developed a fast, simple and fully automated analytical method for determination of indomethacin and its two impurities in pharmaceutical preparation using HPLC with UV detection. Various stationary phases were tested, especially new types of Zorbax columns made by Agilent. While the conventional C18 stationary phases were not convenient enough to achieve quick and reliable separation, Zorbax-Phenyl analytical column (75 mm x 4.6 mm, 3.5 microm) enables separation of indomethacin and its two degradation products during 7.5 min. Chromatography was performed using isocratic elution with binary mobile phase composed of acetonitrile and 0.2% phosphoric acid (50:50, v/v) at flow rate 0.6 ml/min. Even faster separation of standards was obtained with analytical column Zorbax SB-CN (150 mm x 4.6 mm, 5 microm). The separation was effected with mobile phase of the same composition, only the flow rate was increased to 1.2 ml/min. The analytical run was shortened to 5 min. Both methods use detection wavelength 237 nm and both can use either ketoprofen or flurbiprofen as internal standard for quantitation. The first method was finally chosen for validation because of the occurrence of placebo interferences in the case of using Zorbax SB-CN. System suitability parameters and validation parameters including method precision, accuracy, linearity, selectivity and robustness were set up. Afterwards, the method was successfully applied for the practical determination of indomethacin and its degradation products in a topical gel and for compound degradation control during stability studies.

Administration, Topical↗
PubMed2005

Effect of phosphate on the expression of protein-Ser/Thr kinase pkg2 in Streptomyces granaticolor.

A time-correlated expression of eukaryotic-like protein Ser/Thr kinase Pkg2 of Streptomyces granaticolor was investigated by reverse transcriptase-polymerase chain reaction (RT-PCR) and by transcriptional fusion experiments. In a complex medium the activity of pkg2 promoter was constant during the life cycle. Direct RNA analysis proved the presence of corresponding pkg2 transcript. S1 nuclease protection analysis of the transcription initiation site showed that pkg2 gene is expressed as a leaderless mRNA. Under phosphate starvation the promoter activity was detectable merely in the early exponential phase. Under these conditions turning off of pkg2 promoter and cessation of pkg2 transcript level coincided with the start of granaticin production.

Catechol 2,3-Dioxygenase↗
PubMed2004

Simultaneous HPLC determination of ketoprofen and its degradation products in the presence of preservatives in pharmaceuticals.

A novel and quick high-performance liquid chromatography (HPLC) method with UV spectrophotometric detection was developed and validated for the determination of five compounds in topical gel. The described method is suitable for simultaneous determination of active component ketoprofen, two preservatives methylparaben and propylparaben and two degradation products of ketoprofen--3-acetylbenzophenone and 2-(3-carboxyphenyl) propionic acid--in a topical cream after long-term stability tests using ethylparaben as an internal standard. The chromatographic separation was performed on a 5microm Supelco Discovery C18 column (125mm x 4mm i.d., Sigma-Aldrich); the optimal mobile phase for separation of ketoprofen, methylparaben, propylparaben, degradation products 3-acetylbenzophenone and 2-(3-carboxyphenyl) propionic acid and ethylparaben as internal standard consists of a mixture of acetonitril, water and phosphate buffer pH 3.5 (40:58:2, v/v/v). At a flow rate of 1.0ml min(-1) and detection at 233nm, the total time of analysis was less than 10min. The method was applied for routine analysis (batch analysis and stability tests) of these compounds in topical pharmaceutical product.

Chromatography, High Pressure Liquid↗
PubMed1996

[Treatment of inoperable non-small cell bronchogenic carcinoma with a combination of cisplatin and vinorelbine--preliminary evaluation].

The optimal therapeutic approach to patients with inoperable non-small-cell carcinoma is still a matter of discussion. The reason is that chemotherapy improves the quality of life only in some patients. It prolongs their life only by several weeks. In recent years in this indication a new cytostatic is tested--vinorelbine which when used in monotherapy achieves a therapeutic response in 16--30%. In clinical trials of phase 2 a combination of vinorelbine and cisplatinum was most effective and therefore it was selected for the third phase of clinical trials. In the Czech Republic a clinical investigation was made with the objective to verify published data on the success of treatment, evaluate undesirable effects and consider whether it is suitable for routine use. Cisplatinum (Platidiam Lachema) was administered--80 mg/m2 on the first day, vinorelbine (Navelbine Pierre Fabre)--30 mg/m2 on the first and eighth day. The cycle was repeated on the 22nd day. All patients were treated for 12 weeks. Then followed the first evaluation and treatment was continued only in patients with regression or stabilization of the disease. In the group of 126 patients in 44 (35%) partial and in 3 (2.3%) complete therapeutic responses were obtained. In 35 (27%) the disease was evaluated during treatment as stabilized, in 38 (30%) of the patients the disease progressed despite treatment. The tolerance of treatment was, when effective antiemetic treatment was used (ondansetrone or granisetrone), relatively satisfactory.

Antineoplastic Agents↗
PubMed1992

Differential sensitivity of the brain ATP-dependent and GTP-dependent succinyl-CoA synthetase to vanadium ions. Developmental aspects.

We have recently found that both vanadate and vanadyl inhibit ATP-dependent succinyl-CoA synthetase (A-SCS) solubilized from the rat brain mitochondria. Aim of the present study was to estimate a proportion of A-SCS to G-SCS in adult and 5-day-old rat brain and their susceptibility to vanadium ions. The G-SCS to A-SCS ratio of 5-day-old brains was by 196% higher than that in adults. This is in accordance with previous observation that G-SCS is high in tissues metabolizing ketone bodies. Both G-SCS and A-SCS differ in their susceptibility towards vanadium ions. A-SCS of adult brain was more sensitive to vanadate (IC 50 1.6.10(-5) mol.l-1) than was G-SCS (IC 50 6.2.10(-5) mol.l-1). On the contrary G-SCS was more sensitive to vanadyl (IC 50 3.5.10(-4) mol.l-1) than was A-SCS (IC 50 9.0.10(-4) mol.l-1). Also autophosphorylation of G-SCS a-subunit was more resistant to vanadate than A-SCS. In contrast to the adult SCS forms, almost equal susceptibility of A-SCS and G-SCS to vanadyl and vanadate was observed in infant brains. The results suggest some structural (functional) differences between two SCS forms in adults and also between infant and adult G-SCS.

Aging↗
PubMed1991

A novel effect of vanadium ions: inhibition of succinyl-CoA synthetase.

Effect of vanadate and vanadyl ions on the ATP-dependent succinyl-CoA synthetase (A-SCS) solubilized by Lubrol-PX from the rat brain mitochondria was tested. Vanadate added to the assay medium at 10(-5) mol.l-1 and 10(-4) mol.l-1 concentrations inhibited the enzyme activity by about 50% and 94%, respectively. When the enzyme was solubilized from the mitochondria preincubated with 10(-4) mol.l-1 and 10(-3) mol.l-1 vanadate, the residual inhibitions were 55% and 100% respectively. The vanadyl cation also induced inhibition of the A-SCS activity but the effect was less expressed. At 10(-4) mol.l-1 concentration only 20% inhibition was achieved. The A-SCS solubilized from the mitochondrial subfractions (perikaryal, light and heavy synaptosomal) differed neither in the activity of A-SCS nor in the susceptibility toward action of vanadium ions. A strong dependence of the vanadate inhibition on the concentration of succinate was observed. The above effect (50% inhibition) could be demonstrated only at saturating concentration of succinate (50 mmol.l-1). The mechanism of vanadium ions action as well as differences between vanadate and vanadyl ions effects are discussed.

Animals↗
PubMed1988

Does vanadyl affect adenylate cyclase?

While the stimulatory effect of vanadate, an anion of pentavalent vanadium, on adenylate cyclase (AC) has been repeatedly demonstrated in various tissues only a few studies have been hitherto devoted to the effect of vanadyl, a cation of tetravalent vanadium, but these have provided contradictory results. In the present experiments synaptic plasma membranes from normal rat cerebral cortex were used for estimation of the vanadyl effect (in the concentration range from 10(-5) mol.1(-1) to 10(-3) mol.1(-1) on the basal adenylate cyclase activity. Four types of incubation media were used. In the presence of Tris-maleate and creatine phosphate + creatine phosphokinase (CP + CK) maximal stimulation (33%) was reached at 10(-4) mol.1(-1). In the same buffer but in absence or (CP + CK) maximum was already obtained at 10(-5) mol.1(-1) (49%); at 10(-3) mol.1(-1) no effect was observed. In Tric.HCl buffer with (CP + CK) maximal stimulation appeared at 10(-5) mol.1(-1), whereas at 10(-3) mol.1(-1) inhibition (-25%) was observed. In a medium containing Tris.HCl without (CP + CK) the biphasic nature of vanadyl effect was less markedly expressed: maximal stimulation (+55%) occurred at 10(-4) mol.1(-1). Thus vanadyl stimulates AC, but at relatively low concentrations (10(-5)-10(-4); at higher concentration it tends to exert an inhibitory action. Vanadate had a qualitatively similar effect, but the stimulation was more pronounced and the tendency to inhibition was shifted to higher concentrations.

Adenylyl Cyclase Inhibitors↗
PubMed1987

Pseudomonas aeruginosa. II. Experimental acellular vaccine of an endotoxin and anatoxin type.

The results are given of quality evaluation of endotoxin and exotoxin antigens isolated from P. aeruginosa strains. The isolates were tested by both in vitro and in vivo methods. The results of an active protection test on white mice formed the basis for the construction of an experimental Pseudomonas vaccine that protects the immunized animals against infection even by heterologous strains of P. aeruginosa.

Animals↗
PubMed1979

[Monitoring the helmintological situation in a large-scale reproduction of pigs].

In 1976 to 1978, the occurrence of helminths in a large reproduction herd of pigs was studied in different age categories of the animals kept. Six helminth species were found in 30.7% of the sows: Ascaris suum (6.6%), Oesophagostomum dentatum (24.0%), Hyostrongylus rubidus (3.3%), Trichocephalus suis (1.3%), Strongyloides ransomi (0.7%), Metastrongylus sp. (0.3%). Four- to seven-month-old auction gilts had only the eggs of A. suum (4% of all cases). No helminith eggs were found in fattened piglets. Breeding boars were invaded by the species O. dentatum, H. rubidus and Metastrongylus sp. In elite herds and in gilts introduced from these herds, a higher extensity of invasion by different helminth species was found during quarantine and the findings even included the eggs of the species Capillaria sp. The anthelmintic effectiveness of Helmirazin (SpOFA) was also tested: in A. suum its effectiveness was 77.1%, in O. dentatum 66.2%, in T. suis the preparation remained ineffective. The technology of large-scale pig breeding under the conditions of reproduction herd of the PM-013-AGP type appears to be suitable from the helminthological points of view. In the planned introduction of animals from other breeding establishments it is necessary to subject the gilts to double treatment with an effective anthelmintic.

Animals↗