Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “phasing”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,117 records · Page 62Linked to original sources
PubMed2003

A new type of chemically bonded phase for reversed-phase HPLC.

A new type of ether-bonded packing for reversed-phase HPLC (RP-HPLC) was synthesized by reacting 1-octanol with beta-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, followed by coupling the product onto porous silica. The prepared packing was characterized by elemental analysis, solid-state 13C NMR, and Fourier transform infrared (FT-IR) spectroscopy. Chromatographic evaluations were performed by using a mixture of organic compounds as the analyte and methanol-water as binary mobile phase. The influence of the composition of organic modifier on the retention behavior of basic compounds was studied. The hydrolytic stability of the packing between pH 2.5-7.5 was also investigated. The results showed that the new stationary phase has excellent chromatographic properties and good hydrolytic stability.

Journal Article↗
PubMed1982

Phase I and early phase II studies on human urinary colony stimulating factor.

This report demonstrates the first trial for the clinical application of human urinary colony stimulating factor (CSFHU) which was highly purified and well characterized in our laboratory. In the Phase I study, 6 healthy volunteers were administered with 2.5 x 10(5) to 10(6) units of CSFHU intravenously. CSFHU did not show any severe side effects, although slight depression of maximum blood pressure was observed in the group injected with 10(6) units CSFHU and one volunteer who received 5 x 10(5) units CSFHU complained sweating and itching during the infusion. In the Phase II study, six cases suffering from leukocytopenia induced by anticancer drugs or irradiation were treated with 7 day intravenous CSFHU injections. Although recovery of leukocyte number was not observed in the group injected with 7 x 10(6) units CSFHU, complete or partial recovery of leukocyte and granulocyte number was observed in the group injected with 1.3 to 1.4 x 10(7) units CSFHU. Phase II study in a large scale is under way to evaluate further the effectiveness of CSFHU on leukocytopenic patients.

Adolescent↗
PubMed1984

Studies related to the metabolism of anabolic steroids in the horse: the phase I and phase II biotransformation of 19-nortestosterone in the equine castrate.

The metabolism of 19-nor[4-14C]testosterone has been studied in the equine castrate. Following XAD-2 extraction of aliquots of the 0-24 h urine samples, the glucuronic acid and sulphate conjugates were separated by Sephadex LH-20 column chromatography. After hydrolysis of the conjugates, the neutral phase I metabolites of 19-nortestosterone were extracted, purified and identified by g.l.c.-mass spectrometry. In phase I metabolism stereospecificity was observed in the reduction of the A-ring with the formation of the 5 alpha, 3 beta-isomers of estranediol. Epimerization at C-17 and hydroxylation at C-16 were the other major pathways. In phase II metabolism the C-17 alpha steroid epimers were predominantly conjugated with glucuronic acid and the C-17 beta epimers with sulphuric acid. One animal showed a slight variation in metabolism with a tendency towards the formation of polar metabolites.

Animals↗
PubMed1998

The human phase response curve (PRC) to melatonin is about 12 hours out of phase with the PRC to light.

Melatonin's timekeeping function is undoubtedly related to the fact that it is primarily produced during nighttime darkness; that is, melatonin and light occur at opposite times. The human phase response curve (PRC) to melatonin appears to be about 12h out of phase with the PRC to light. These striking complementarities, together with light's acute suppressant effect on melatonin production, suggest that a function for endogenous melatonin is to augment entrainment of the circadian pacemaker by the light-dark cycle. The melatonin PRC also indicates correct administration times for using exogenous melatonin to treat circadian phase disorders.

Adult↗
PubMed2000

Rifapentine and isoniazid in the continuation phase of a 6-month regimen. Interim report: no activity of isoniazid in the continuation phase.

SETTING: Clinical trial amongst 762 patients with newly diagnosed pulmonary tuberculosis in Hong Kong. After an initial 2 months of a four-drug intensive phase consisting of streptomycin, isoniazid, rifampicin and pyrazinamide (SHRZ), a random allocation in continuation to once-weekly rifapentine + isoniazid (HRp1), HRp1 given in 2 of every 3 weeks (HRp1.2/3), or to three times weekly isoniazid + rifampicin (HR3). OBJECTIVE: Interim report evaluating progress of study and the role of isoniazid in the continuation phase. METHODS: Kaplan-Meier analysis and response of patients related to susceptibility of pretreatment organisms to isoniazid and to rate of isoniazid acetylation determined by NAT2 genotyping. RESULTS: In the 30-month follow-up, rates for adverse treatment events (failure and relapse) were 4.2% in the HR3, 10.2% in the HRp1 and 11.2% in the HRp1.2/3 series (P = 0.02 for HR3 vs HRp1 and P = 0.01 for HR3 vs HRp1.2/3). Occurrence of adverse events was not related to initial susceptibility to isoniazid nor to the rate of acetylation of isoniazid. CONCLUSIONS: The two rifapentine regimens had similar final rates of adverse events which were unsatisfactory. Isoniazid had little or no activity in the continuation phase, indicating that no improvement of the continuation regimen is likely to be obtained by alteration of the isoniazid dosage.

Acetylation↗
PubMedDate not supplied

Optimization of the separation of some Chelidonium maius L. alkaloids by reversed phase high-performance liquid chromatography using cyanopropyl bonded stationary phase.

The high-performance liquid chromatographic method using two stationary phases: RP-18 and cyanopropyl silica for the analysis of some alkaloids in Chelidonium maius L. extracts is performed. The extract was chromatographed using a mobile phase composed of an organic modifier (acetonitrile, methanol, tetrahydrofuran or 1,4-dioxan), phosphate buffer and sodium octadecylsulfate or di (2-ethyl hexyl) orthophosphoric acid (HDEHP) as ion-pairing reagents. The influence of the different kind of stationary phase and organic modifiers on retention has been compared. In order to improve the selectivity of separation and peak shape, gradient elution was applied.

Alkaloids↗
PubMed2002

[Differences in gene expression between Taxus chinensis cells during Taxol-synthesis phase and those during non-Taxol-synthesis phase].

In plant, evocation of secondary metabolism is associated with complex biochemical and molecular events that are regulated by developmental and environmental factors. In order to get more information about Taxol biosynthesis, comparison of mRNA populations from Taxus chinensis cells during Taxol-synthesis phase and those during non-Taxol-synthesis phase were performed by mRNA differential display. The results suggested that genes specifically expressed in the Taxol-synthesis phase might be involved in Taxol biosynthesis.

Gene Expression Regulation, Developmental↗
PubMed2003

[Analysis of the polymorphic alleles of genes encoding phase 1 and phase 2 detoxication enzymes in patients with endometriosis].

Polymorphysms of the three genes encoding phase 1 (CYP1A1, mEPH1, and CYP2E2) and the three genes encoding phase 2 (NAT2, GSTM1, and GSTT1) xenobiotic detoxication enzymes were typed by use of PCR in 74 patients with extragenital endometriosis. Distribution of the CYP1A1, mEPHX1, CYP2E1, NAT2, and GSTM1 polymorphic alleles in the patient group corresponded to that in the control group. At the same time, functionally defective genotypes GSTM1 0/0, NAT2 S/S; GSTM1 0/0, GSTT1 0/0; and GSTT1 0/0, NAT2 S/S were three, four and eight times more frequent among the patients than in healthy individuals. This observation suggests the existence of a distinct association between the functionally defective alleles of the phase 2 xenobiotic detoxication and endometriosis. Possible mechanisms underlying this association are discussed. It is suggested that typing of the NAT2, GSTM1, and GSTT1 genes can be useful for the assessment of the predisposition to endometriosis.

Alleles↗
PubMedDate not supplied

Phase transfer catalysis in solid phase peptide synthesis. Preparation of cyclo[Xxx-Pro-Gly-Yyy-Pro-Gly] model peptides and their conformational analysis.

Relatively small cyclic peptides that contain functionalized side chains provide interesting model compounds for studying side chain-side chain interactions, peptide backbone flexibility (especially if X-Pro bonds are included), and as potential enzyme mimetics. In order to develop more efficient synthetic routes to compounds such as cyclo(Xxx-Pro-Gly-Yyy-Pro-Gly), using the Merrifield method, we have investigated several orthogonal solid phase synthesis strategies and contrasted the use of two solid phase peptide-resin cleavage techniques for preparing partially protected linear sequences. Phase transfer catalysis using tetrabutyl ammonium hydrogen sulfate in THF with saturated aqueous K2CO3 provides peptide acid salts in which most of the common protecting groups (Arg(NO2), Tyr(Bzl), Z-Lys, Lys(Boc), and Glu(tBu)) are not affected. Using 500 MHz proton NMR, peptides having a cyclo (L-L-Gly-L-L-Gly) sequence generally display two conformers in DMSO-d6 with the major isomer being the bis-cis conformer, while the minor form contains two beta turns. For peptides with a cyclo(D-L-Gly-L-L-Gly) sequence, the major conformer contains one cis and one trans X-Pro bond and one Type II beta turn, as previously predicted for related structure by Kopple and others.

Catalysis↗
PubMed2004

Influence of inorganic mobile phase additives on the retention, efficiency and peak symmetry of protonated basic compounds in reversed-phase liquid chromatography.

Inorganic eluent additives affect the retention of protonated basic analytes in reversed-phase HPLC. This influence is attributed to the disruption of the analyte solvation-desolvation equilibria in the mobile phase, also known as "chaotropic effect". With an increase of counteranion concentration analyte retention increases with concomitant decrease in the tailing factor. Different inorganic counteranions at equimolar concentrations affect protonated basic analyte retention and peak symmetry to varying degrees. The effect of the concentrations of four different inorganic mobile phase additives (KPF6, NaClO4, NaBF4, NaH2PO4) on the analyte retention, peak symmetry, and efficiency on a C8-bonded silica column has been studied. The analytes used in this study included phenols, toluene, benzyl amines, beta-blockers and ophthalmic drugs. The following trend in increase of basic analyte retention factor and decrease of tailing factor was found: PF6- > ClO4- approximately BF4- > H2PO4-. With the increase of the counteranion concentration greater analyte loading could be achieved and consequently an increase in the apparent efficiency was observed until the maximum plate number for the column was achieved. At the highest concentration of counteranions, the peak efficiency for most of the basic compounds studied was similar to that of the neutral markers. In contrast, the neutral markers, such as phenols, showed no significant changes in retention, efficiency or loading capacity as counteranion concentration was increased.

Algorithms↗
PubMed1990

Phase-shifting effects of bright morning light as treatment for delayed sleep phase syndrome.

Bright light has recently been shown to have phase-shifting effects on human circadian rhythms. In this study we applied this effect to 20 patients with delayed sleep phase syndrome (DSPS) who were unable to fall asleep at conventional clock times and had a problem staying alert in the morning. In a controlled treatment study, we found that 2 h of bright light exposure in the morning together with light restriction in the evening successfully phase advanced circadian rhythms of core body temperature and multiple sleep latencies in these patients. This finding corroborates the importance of light for entraining human circadian rhythms.

Arousal↗
PubMed1975

Phase II to phase I conversion of Coxiella burneti in immunosuppressed mice.

Coxiella burneti strains 48 and Nine Mile, serologically in phase II, changed their antigenic properties and virulence for guinea pigs and mice upon passaging in immunosuppressed mice. Conversion to phase I of these strains in a system lacking antibody response throws doubt on the importance of specific antibodies in phase variation of C. burneti.

Animals↗
PubMed1989

Effects of dietary benzo(a) pyrene on intestinal phase I and phase II drug metabolizing systems in normal and vitamin A-deficient rats.

Feeding of vitamin A-deficient diet to male weanling rats for 10 weeks caused significant increase in the activities of Phase I enzyme system, i.e., cytochrome P-450, cytochrome b5 and arylhydrocarbon hydroxylase in the proximal, middle and distal segments of the intestine. Of the Phase II enzymes studied, UDP-glucuronyltransferase showed significant decrease whereas glutathione S-transferase showed significant increase. Treatment with benzo(a)pyrene caused greater induction in the levels of Phase I enzymes in deficient animals as compared to controls. In contrast to this, benzo(a)pyrene treatment induced the level of UDP-glucuronyltransferase in control rats more than in deficient rats. Intestinal NADPH cytochrome C-reductase and glutathione S-transferase remained insensitive to benzo(a)pyrene induction.

Animals↗
PubMed1978

[Pharmacological effects of phase-I- and phase-II-metabolites of triamterene (author's transl)].

Since triamterene (TA) is rapidly metabolized to hydroxytriamterene (OH-TA) and then to its sulfuric acid ester (OH-TA-ester) the question arose whether the metabolites are still effective on ion transport as is triamterene. The effect of the metabolites was studied in microperfusion experiments on the rat submaxillary duct, which resembles the distal nephron and is considered the site of action of triamterene. Added to the lumen the phase-I- as well as the phase-II-metabolites decreased reabsorption of Na+, secretion of K+, and yielded an accumulation of HCO3-. These effects of the metabolites were produced by equimolar concentrations and are almost identical to those of native triamterene. In conclusion, the phase-II-metabolite must be considered to be essentially responsible for the natriuresis and antikaliuresis observed after oral administration of triamterene.

Animals↗
PubMedDate not supplied

[Phase transition studies of model and biological membranes. I. Use of hydrophobic fluorescent probes for studying phase transitions in liposomes].

Phase transition induced by temperature changes in liposomes prepared from synthetic dimyristoyl-(DML), dipalmytoyl-(DPL) and distearyl-(DSL) lecithins and also from equimolar mixture of DML and DPL and mixtures of DPL and cholesterol were studied with fluorescent probes such as 3-metoxybenzantron (MBA) and dimetylaminocholkone (DMC). The significant changes of fluorescence intensity and maximum position of MBA and DMC were found in the regions of phase transitions at 23, 42, 54 and 31c in liposomes from DML, DPL, DSL and mixture of DML and DPL, respectively. Cholesterol incorporation into liposomes from DPL led to a decrease of transition temperature and cooperativity for these liposomes. At cholesterol concentration of 20 mol. percent or more the transition disappeared completely. It is concluded that MBA and DMC can be used for the investigation of biological membranes phase transitions.

Cholesterol↗
PubMed1981

Phase-shift markers in the genus Bordetella: loss of cytochrome d-629 in phase IV variants.

The respiratory electron transport chain of Bordetella pertussis was examined in whole cell suspensions using difference spectra obtained at room temperature. Phase I (virulent) strains were found to possess cytochromes a-603, b-560, c-550, d-629 and cytochrome o. Cytochrome c-553, previously reported (Sutherland, 1963) was not detected and was assumed to be masked by the alpha-peaks for c-550 and b-560. Phase IV (avirulent) strains and C-mode cells (phase I strains grown in the presence of 20 mM MgSO4) were deficient in cytochrome d-629 and appeared to have higher levels of cytochromes a-603, b-560, c-550 and cytochrome o. Preliminary data indicate that B. parapertussis and B. bronchiseptica have electron transport chains similar to that of B. pertussis.

Bordetella↗
PubMedDate not supplied

Comparison of human and rhesus monkey in vitro phase I and phase II hepatic drug metabolism activities.

Twelve human and six rhesus monkey liver samples were analyzed in vitro for phase I metabolism and phase II conjugation activity. Of the eight P-450-dependent activities measured, only N-nitrosodimethylamine N-demethylase activity was not significantly different between the two species. Coumarin 7-hydroxylase activity was greater in the human as compared with the rhesus monkey samples, whereas erythromycin N-demethylase, benzphetamine N-demethylase, pentoxyresorufin O-dealkylase, ethoxycoumarin O-deethylase, and ethoxyresorufin O-deethylase activities were significantly greater in rhesus monkey microsome samples (p < or = 0.01). Cimetidine S-oxygenation and chlorpromazine N-oxygenation were 2.1- and 2.6-fold higher in rhesus monkey samples. Of the seven microsomal and cytosolic phase II activities measured, only 17 alpha-ethynylestradiol glucuronidation was significantly higher in the human samples. The genetic polymorphism for isoniazid acetylation was evident only in the human samples, with activities varying 200-fold. This study shows that, although the rhesus monkey is often used by the pharmaceutical industry as a representative mammalian species for drug testing, the in vitro metabolic capabilities of the human and rhesus monkey drug metabolizing enzymes are different.

Animals↗
PubMed1997

[Myocardial wall motion analysis with phase shift imaging: cine phase contrast technique].

MR imaging can be used to measure proton velocity directly as a phase shift with the bipolar gradient method. This method is applied in MR angiography as a phase contrast(PC) technique. We attempted to evaluate myocardial motion utilizing the PC technique. With the cine PC technique, 16-cardiac phased 3D velocity images of the myocardium were obtained. In normal subjects, the myocardial velocity throughout the cardiac cycle were changes regular in space as well as in time, and there was no inconsistency between the motion directions. Whereas, in cases with myocardial infarction, 3D velocity images revealed some regions with zero velocity and/or some regions which showed reverse direction motions compared with the surrounding normal myocardium.

Heart↗