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208 records · Page 12Linked to original sources
PubMed2003

TLC and HPLC characteristics of desacetylmatricarin, leucodin, achillin and their 8alpha-angeloxy-derivatives.

Five guaianolides, including two pairs of isomers, from a Hungarian taxon of the Achillea millefolium group were characterized analytically. Different chromatographic systems on TLC and HPLC were developed for the analysis of these compounds. TLC of leucodin, 8alpha-angeloxy-leucodin, achillin, 8alpha-angeloxy-achillin and desacetylmatricarin was performed on silica gel using dichloromethaneacetone and cyclohexane-ethylacetate mixtures as mobile phases. HPLC on stationary phases as LiChrospher RP2, LiChrospher RP8, LiChrospher RP18e, Hypersil BDS C18 and Aquasil C18 required isocratic and gradient systems with different methanol-water mixtures as mobile phases. The presented RF values and retention times allow the identification of the respective 2-oxo-guaianolides which are marker substances for certain non-proazulene containing species. Their TLC and HPLC fingerprints are compared to those of proazulene containing species and are relevant for quality control.

Achillea↗
PubMed1992

[Direct injection of plasma to determine gliquidone in plasma using HPLC column switching technique].

An automated clean up and concentration method by column switching is described for the assay of gliquidone, a hypoglycemic agent, in plasma. The system uses Merck Lichroprep RP2 (25-40 microns) as short precolumn packing material for on--line clean up and concentration. A Shimpack CLC--ODS (5 microns) is used as analytical column. Water is used as the pretreatment mobile phase and a mixture of methanol--isopropanol--0.2 mol/L ammonium acetate solution (61:5:34) is used as the analytical mobile phase. The plasma is diluted with a solution of 0.2 mol/L acetic acid and injected directly on the precolumn. The low speed of 0.2 ml/min of pretreatment mobile phase during transfer of plasma sample on the precolumn can get recovery of 80.7%. The detection is at 310 nm and the detection limit is 30 ng/ml plasma. The procedure is simple and automatic.

Chromatography, High Pressure Liquid↗
PubMed2003

Postsynaptic protein kinase A reduces neuronal excitability in response to increased synaptic excitation in the Drosophila CNS.

Previous work has identified a role for synaptic activity in the development of excitable properties of motoneurons in the Drosophila embryo. In this study the underlying mechanism that enables two such neurons, termed aCC and RP2, to respond to increased exposure to synaptic excitation is characterized. Synaptic excitation is increased in genetic backgrounds that lack either a cAMP-specific phosphodiesterase (EC:3.1.4, dunce) or acetylcholinesterase (EC:3.1.1.7, ace), the enzyme that terminates the endogenous cholinergic excitation of these motoneurons. Analysis of membrane excitability in aCC/RP2, in either background, shows that these neurons have a significantly reduced capability to fire action potentials (APs) in response to injection of depolarizing current. Analysis of underlying voltage-gated currents show that this effect is associated with a marked reduction in magnitude of the voltage-dependent inward Na+ current (INa). Partially blocking INa in these motoneurons, using low concentrations of TTX, demonstrates that a reduction of INa is, by itself, sufficient to reduce membrane excitability. An analysis of firing implicates an increased AP threshold to underlie the reduction in membrane excitability observed because of heightened exposure to synaptic excitation. Genetic or pharmacological manipulations that either elevate cAMP or increase protein kinase A (PKA) activity in wild-type aCC/RP2 mimic both the reductions in membrane excitability and INa. In comparison, increasing cAMP catabolism or inhibition of PKA activity is sufficient to block the induction of these activity-dependent changes. The induced changes in excitability can be rapid, occurring within 5 min of exposure to a membrane-permeable cAMP analog, indicative that threshold can be regulated in these neurons by a post-translational mechanism that is dependent on phosphorylation.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMedDate not supplied

The chromatographic data in QSAR assay of TIQs derivatives with beta2-adrenergic activity.

We performed QSAR analysis of beta2-adrenergic activity and chromatographic data of 4,6,8-trihydroxy-, 6,7-dihydroxy- and 6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline derivatives. TLC plates (silica gel NP 60F(254) and silica gel RP2 60F(254) silanised precoated), impregnated with solutions of analogues of the selected amino acids were used as beta2-agonistic and antagonistic interaction models. QSAR analysis of the beta2-adrenergic activity and the chromatographic data of the solutes were made. A correlation between biological data and behaviour of the examined compounds in a chromatographic modifiable environment (S1-S3) was investigated by the linear regression analysis method.

Adrenergic beta-Agonists↗
PubMed2005

Detection of giardine gene in local isolates of Giardia duodenalis by polymerase chain reaction (PCR).

Giardia duodenalis is an intestinal parasite that causes diarrhoea and malabsorption in children. The parasite also infects AIDS patients with a weak immune system. A study was carried out on six local isolates of Giardia duodenalis (110, 7304, 6304, M007, 2002 and 6307) from faeces of Orang Asli patients admitted to the Gombak Hospital. WB, a reference pathogenic strain from human and G. muris from a wild mouse, were commercially obtained from the American Type Culture Collection (ATCC). All the isolates were cultured axenically in TYI-S-33 medium. Two sets of primers were used for the techniques: primers LP1 and RP1 and primers LP2 and RP2. The sets of primers amplified giardine gene of 171 bp and 218 bp in sizes respectively. The study showed that the two sets of primers could detect G. duodenalis to the genus and species level specifically.

Animals↗
PubMed1983

[Identification of hemoglobin D Punjab (beta 121 glu replaced by gln) in an Austrian family. Sequence analysis of the abnormal tryptic peptide beta XTp13].

In the course of a screening programme for gestational diabetes an abnormal haemoglobin fraction was detected by high-performance liquid chromatography (HPLC), used for Hb A1c-quantification. Cellulose acetate electrophoresis revealed a heterozygote haemoglobinopathy with approximately equal amounts of Hb A1 and of an abnormal haemoglobin which migrated in the position of Hb S under the conditions used. Preparative separation of these haemoglobin components was performed by use of a DEAE-cellulose column and standard conditions. alpha- and beta-chains were isolated with CM-sepharose and buffer containing 8M urea. The abnormal component of the aberrant haemoglobin was found to be the beta-chains in reconstitution experiments with globin-chains and haemin. A tryptic hydrolysate of the isolated abnormal beta-chains was analysed by means of HPLC and a C2 reverse phase (RP2). Rechromatography of the abnormal fractions on a C18 reverse phase (ODS) led to a pure preparation of peptide beta XTp13. The amino acid sequence analysis of this peptide showed an exchange of glutamic acid to glutamine in position beta 121 (beta 121 Glu----Gln). By these means evidence was obtained for the existence of a heterozygote Hb D Punjab state in the observed patient.

Adult↗
PubMed1994

Determination of fluconazole by direct injection of plasma and high performance liquid chromatography with column switching.

High performance liquid chromatography with column switching has been developed for the determination of fluconazole in plasma. The plasma samples were injected onto a precolumn packed with LiChromprep RP2(25-40 microns) after simple dilution with a solution of 0.2 mol.L-1 acetic acid. Distilled water was used to wash out protein and other polar components in plasma. After switching, the concentrated fluconazole was eluted in the back-flush mode onto a Shimpack CLC-ODS column with methanol--0.2 mol.L-1 ammonium acetate (pH 2.7) (50:50) as mobile phase. Purge solutions were used for clean-up and for regenerating the precolumn. The method showed a good precision and excellent recovery. The detection limit was 0.12 micrograms.ml-1 plasma. The RSD's (intra- and interday) were less than 6.3%. The method has been successfully used to determine bioavailability and pharmacokinetics of fluconazole in Chinese volunteers.

Adult↗
PubMed1994

Genetic analysis of a kindred with X-linked mental handicap and retinitis pigmentosa.

A kindred is described in which X-linked nonspecific mental handicap segregates together with retinitis pigmentosa. Carrier females are mentally normal but may show signs of the X-linked retinitis pigmentosa carrier state and become symptomatic in their later years. Analysis of polymorphic DNA markers at nine loci on the short arm of the X chromosome shows that no crossing-over occurs between the disease and Xp11 markers DXS255, TIMP, DXS426, MAOA, and DXS228. The 90% confidence limits show that the locus is in the Xp21-q21 region. Haplotype analysis is consistent with the causal gene being located proximal to the Xp21 loci DXS538 and 5'-dystrophin on the short arm of the X chromosome. The posterior probability of linkage to the RP2 region of the X chromosome short arm (Xp11.4-p11.23) is .727, suggesting the possibility of a contiguous-gene-deletion syndrome. No cytogenetic abnormality has been identified.

Adolescent↗
PubMed1996

A recombination outside the BB deletion refines the location of the X linked retinitis pigmentosa locus RP3.

Genetic loci for X-linked retinitis pigmentosa (XLRP) have been mapped between Xp11.22 and Xp22.13 (RP2, RP3, RP6, and RP15). The RP3 gene, which is responsible for the predominant form of XLRP in most Caucasian populations, has been localized to Xp21.1 by linkage analysis and the map positions of chromosomal deletions associated with the disease. Previous linkage studies have suggested that RP3 is flanked by the markers DXS1110 (distal) and OTC (proximal). Patient BB was thought to have RP because of a lesion at the RP3 locus, in addition to chronic granulomatous disease, Duchenne muscular dystrophy (DMD), mild mental retardation, and the McLeod phenotype. This patient carried a deletion extending approximately 3 Mb from DMD in Xp21.3 to Xp21.1, with the proximal breakpoint located approximately 40 kb centromeric to DXS1110. The RP3 gene, therefore, is believed to reside between DXS1110 and the proximal breakpoint of the BB deletion. In order to refine the location of RP3 and to ascertain patients with RP3, we have been analyzing several XLRP families for linkage to Xp markers. Linkage analysis in an American family of 27 individuals demonstrates segregation of XLRP with markers in Xp21.1, consistent with the RP3 subtype. One affected mate shows a recombination event proximal to DXS1110. Additional markers within the DXS1110-OTC interval show that the crossover is between two novel polymorphic markers, DXS8349 and M6, both of which are present in BB DNA and lie centromeric to the proximal breakpoint. This recombination places the XLRP mutation in this family outside the BB deletion and redefines the location of RP3.

Adult↗