Biomedical subjects

T V Olah

Publications and source records attributed to T V Olah.

35 records · Page 2Linked to original sources

PubMed1996

Pharmacokinetics and food interaction of MK-462 in healthy males.

A study was conducted to assess the safety, tolerability, and pharmacokinetics of single intravenous (IV) doses of 5-90 micrograms kg-1 of MK-462, and the effect of food on the pharmacokinetics of MK-462 administered orally to healthy males. Results of this study indicate that IV doses of MK-462 from 5 to 90 micrograms kg-1 are well tolerated. The disposition kinetics of MK-462 were linear for IV doses up to and including 60 micrograms kg-1. The values of the plasma clearance (CL), steady-state volume of distribution (Vss), plasma terminal half-life (t1/2), and mean residence time in the body (MRT) of MK-462 averaged 1376 mL min-1, 140 L, 1.8 h, and 1.7 h, respectively, and remained essentially constant over the dosage range of 10-60 micrograms kg-1 of IV MK-462. However, as the dose increased from 60 to 90 micrograms kg-1, the mean value of the apparent CL decreased from 1376 to 807 mL min-1. Thus, elimination of MK-462 was dose dependent in this dosage range. Based on the disposition decomposition analysis (DDA), it was shown that the Vss value of MK-462 remained essentially constant over the dosage range of 10-90 micrograms kg-1 of IV MK-462. The following values of two dose-independent parameters were also calculated by using DDA: distribution clearance (CLd) = 2028 mL min-1, and mean transit time in the peripheral tissues (MTTT) = 0.74 h. The mean values of AUC, Cmax, tmax, and apparent t1/2 of MK-462 in 12 subjects each receiving a 40 mg tablet of MK-462 without breakfast were 330 ng.h mL-1, 77 ng mL-1, 1.6 h, and 1.8 h, respectively. Although administration of a standard breakfast prior to dosing increased the AUC value (by approximately 20%) of MK-462 and delayed its absorption, there were no significant effects of the meal on the values of Cmax and apparent t1/2 of MK-462.

Absorption↗

PubMed1996

Pilot study of MK-462 in migraine.

MK-462 is a potent, selective 5HT1D receptor agonist which may be useful in treating acute migraine. We conducted a double-blind placebo-controlled inpatient study to assess the preliminary efficacy and safety of oral doses of MK-462 20 mg (n = 8) and 40 mg (n = 36) vs placebo (n = 21), administered to 65 male and post-menopausal female migraine patients aged 22-51 with moderate or severe migraine headache. Headache severity and functional disability were measured at 0.5, 1, 1.5, and 2 h post-dose. The 20 mg dose was well tolerated and 4/8 patients obtained relief in headache severity at the 2 h time point. The 40 mg dose was well tolerated and was significantly (p < 0.05) superior to placebo at the 1.5 and 2 h time points (with 27/36 or 75% obtaining relief at 2 h compared to 7/21 or 33% for placebo). Adverse events occurred in 50% of patients on 20 mg MK-462, 72% of those on 40 mg MK-462, and in 52% of placebo-treated subjects. The most common adverse events associated with MK-462 were drowsiness (20 mg 12%; 40 mg 44%; placebo 24%), dry mouth (40 mg 36%; placebo 19%), and lightheadedness/dizziness (40 mg 17%; placebo 10%). Based on these preliminary results, MK-462 appears worthy of continued study for the treatment of acute migraine.

Adult↗

PubMed1995

The development and cross-validation of methods based on radioimmunoassay and LC/MS-MS for the quantification of the class III antiarrhythmic agent, MK-0499, in human plasma and urine.

An analytical method based on radioimmunoassay (RIA) has been developed for the determination of the antiarrhythmic agent, MK-0499, in plasma and urine. Owing to the potency of the drug, the specificity of this assay in human plasma could not be adequately determined using conventional RIA procedures. A highly specific procedure, based on LC/MS-MS, was developed to cross-validate the RIA. The lower quantifiable limits of the RIA and LC/MS-MS-based methods were 0.05 and 0.013 ng ml-1, respectively. Cross-validation data, compared using paired student's t-test regression analysis, showed excellent correlation between methods. The mass spectrometric assay was also used to simultaneously measure plasma concentrations of unlabeled and 14C-labeled MK-0499 following administration of the drug at high specific activity to volunteers.

Animals↗

PubMed1994

A rapid and specific assay, based on liquid chromatography-atmospheric pressure chemical ionization mass spectrometry, for the determination of MK-434 (a 5 alpha-reductase inhibitor) and its metabolites in plasma.

MK-434 is a new 5 alpha-reductase inhibitor. A sensitive and specific assay based on combined liquid chromatography-mass spectrometry (LC-MS) has been developed for the determination of this compound in plasma. The analyte was isolated from plasma by solid-phase extraction on a C18 cartridge. A related substance, L-654,066, was used as the internal standard. Extracts were separated on a 5-cm C18-reversed-phase high performance liquid chromatography column interfaced via the heated nebulizer probe to a corona discharge chemical ionization source. The mass spectrometer was operated in the positive ion MS-MS mode. The method had sufficient sensitivity, precision, accuracy, and selectivity for the analysis of clinical samples containing MK-434 and its two principal metabolites at concentrations in the range 0.5-50 ng ml-1. The chromatographic run time was < 5 min.

5-alpha Reductase Inhibitors↗

PubMed1994

Determination of L-691,121, a new class III antiarrhythmic, and its principal metabolite in plasma by differential radioimmunoassay.

A sensitive and specific method based on radioimmunoassay (RIA) has been developed for the analysis of L-691,121, a new antiarrhythmic agent, and its major metabolite, L-692,199, in plasma. Two RIAs using immunogens and radioligands prepared from different derivatives of L-691,121 were used in conjunction to determine both parent compound and metabolite concentrations by solving simultaneous equations, since neither assay alone was adequately specific. Variable cross-reactivity factors were incorporated into the calculations to correct for non-parallel drug and metabolite displacement curves. The direct assay using 30 microliters of plasma is sensitive to 0.1 ng ml-1 and has sufficient precision, accuracy and specificity for the analysis of clinical samples.

Animals↗

PubMed1994

Determination of MK-383, a non-peptide fibrinogen receptor antagonist, in human plasma and urine by radioimmunoassay.

MK-383 is a novel, non-peptide fibrinogen receptor antagonist. A sensitive and specific radioimmunoassay has been developed for the determination of this drug candidate in plasma and urine. The immunogen was prepared by coupling to albumin via the N-hydroxysuccinimide ester from which the radioligand was also prepared by reaction with [I125]iodotyrosine. The method was specific and no immunoreactive material other than the parent drug was detectable in plasma and urine from dosed volunteers. This direct assay, using 5 microliters of plasma or 0.5 microliter of urine, is sensitive to 1 and 10 ng ml-1, respectively, without matrix interference and has sufficient sensitivity, specificity, accuracy, and precision for the analysis of clinical samples.

Animals↗

PubMed1993

Incorporation of dinitrophenyl derivatives of proteins S6, S13, S16, and S18 into the 30 S subunit of Escherichia coli ribosomes by total reconstitution.

This is the third paper in a series (Olah, T. V., Olson, H. M., Glitz, D. G., and Cooperman, B. S. (1988) J. Biol. Chem. 263, 4795-4800; Olson, H. M., Olah, T., Cooperman, B. S., and Glitz, D. G. (1988) J. Biol. Chem. 263, 4801-4806) describing the use of 2,4-dinitrophenyl (DNP) derivatives of Escherichia coli 30 S ribosomal proteins to locate the positions of these proteins within the 30 S subunit by immune electron microscopy. In it we describe the derivatization of proteins S6, S13, S16, and S18 with [3H]2,4-dinitrofluorobenzene, identify the nature of the derivatized amino acids within each protein, and demonstrate that each DNP protein, denoted DNP-Sx, can be taken up into a reconstituted 30 S subunit when added to a reconstitution mixture containing 16 S rRNA and total 30 S protein depleted in Sx. We further demonstrate that each DNP-Sx binds within the 30 S subunit in a position identical or similar to that of the unmodified Sx protein, as judged by its meeting one or more of the following three criteria: (i) unmodified Sx competes with the uptake of DNP-Sx into 30 S subunits; (ii) DNP-Sx restores functional activity to those single protein omission reconstitution particles lacking full activity; (iii) DNP-Sx induces the uptake of proteins into 30 S subunits that depend on the presence of Sx. The fourth paper in this series (Montesano-Roditis, L., McWilliams, R., Glitz, D. G., Olah, T. V., Perrault, A. R., and Cooperman, B. S. (1993) J. Biol. Chem. 268, 18701-18709), which follows this one, describes the localization of the DNP-Sx proteins within the 30 S subunit by immune electron microscopy.

Amino Acids↗

PubMed1993

Placement of dinitrophenyl-modified ribosomal proteins in totally reconstituted Escherichia coli 30 S subunits. Localization of proteins S6, S13, S16, and S18 by immune electron microscopy.

Purified Escherichia coli ribosomal proteins S6, S13, S16, and S18 were dinitrophenylated at their amino termini and/or at one or more internal lysine residues. Each dinitrophenyl protein was then separately incorporated into reconstituted small ribosomal subunits. Modified proteins were localized on the 30 S subunit surface by electron microscopy of reconstituted subunits complexed with antibodies to dinitrophenol (DNP). DNP protein S13 was placed on the subunit head above the platform and on the surface that faces the large subunit. DNP-S18 was localized to the subunit platform below the tip and in a region associated with binding to 50 S subunits. DNP proteins S6 and S16 were both localized near the junction of the subunit body and platform; DNP-S6 was available to antibody in 70 S ribosomes and was placed on the cytoplasm-facing side of the subunit in an area that overlaps the platform and body of the particle. DNP-S16 in 70 S ribosomes was not bound by antibody. It was localized to the 30 S body near its junction with the platform and on the surface facing the 50 S particle. The results complement and clarify data obtained using other approaches.

Antigen-Antibody Complex↗

PubMed1993

Determination of the beta-adrenergic blocker timolol in plasma by liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.

A method based on LC-MS-MS has been developed for the determination of timolol in plasma using the (CD3)3-labelled species as the internal standard. Timolol is isolated from plasma by a simple solid-phase extraction and converted to its oxazolidin-2-one prior to analysis on a 50 x 4.6 mm reversed-phase high-performance liquid chromatography column packed with SynChropak, C18, 5 microns. The column eluate is passed by means of a heated nebulizer interface into a corona discharge atmospheric pressure chemical ionization source where the analyte and its internal standard are detected using multiple reaction monitoring (MRM). The very high specificity of this technique permits chromatographic run times of less than 2 min. The method has a lower quantifiable limit of 0.5 ng ml-1, with intra- and inter-day relative standard deviations less than 10%, and enables the determination of timolol in plasma after ocular administration to volunteers.

Calibration↗

PubMed1993

Determination of MK-852, a new fibrinogen receptor antagonist, in plasma and urine by radioimmunoassay.

MK-852 is a novel fibrinogen receptor antagonist. A sensitive and specific radioimmunoassay has been developed for the determination of this drug candidate in plasma and urine. The immunogen was prepared by coupling to albumin via a dinitrophenylene bridge and the radioligand by reaction of the drug with the 125I-labelled Bolton-Hunter reagent. The method was specific and no immunoreactive material other than parent drug was detectable in plasma from dosed volunteers. The direct assay using 0.05 ml of plasma is sensitive to 0.2 ng ml-1 without matrix interference and has sufficient sensitivity, precision, accuracy, and selectivity for the analysis of clinical samples. The lower quantifiable limit in (diluted) urine is 50 ng ml-1.

Amino Acid Sequence↗

PubMed1992

Determination of L-365,260, a new cholecystokinin receptor (CCK-B) antagonist, in plasma by liquid chromatography/atmospheric pressure chemical ionization mass spectrometry.

L-365,260 is a novel cholecystokinin receptor antagonist. A sensitive and specific liquid chromatographic/mass spectrometric assay has been developed for the determination of the drug in plasma using the CD3-labeled species as the internal standard. Plasma extracts were separated on a 3 cm C18 reverse-phase high-performance liquid chromatography column. The column eluate passed, by means of a heated nebulizer interface, into a corona discharge atmospheric chemical ionization source. The mass spectrometer was operated in the positive ion tandem mass spectrometric mode. The method has sufficient sensitivity, specificity, precision, accuracy and selectivity for the determination of drug concentrations in clinical samples. The chromatographic run time is less than 2 min.

Benzodiazepinones↗

PubMed1992

Determination of L-654,066, a new 5 alpha-reductase inhibitor in plasma by liquid chromatography/atmospheric pressure chemical ionization mass spectrometry.

L-654,066 is a new 5 alpha-reductase inhibitor. A sensitive and specific assay based on combined liquid chromatography/mass spectrometry has been developed for the determination of this drug candidate in plasma. The analyte was isolated from plasma by solid-phase extraction on a C-18 cartridge. A related substance, L-683,838, was used as the internal standard. Extracts were chromatographed on a 5 cm C18 reverse-phase high-performance liquid chromatography column interfaced via the heated nebulizer probe to a corona discharge chemical ionization source. The mass spectrometer was operated in the positive ion tandem mode. The method has sufficient sensitivity, precision, accuracy and selectivity for the analysis of clinical samples containing L-654,066 at concentrations in the range 0.5-20 ng ml-1. The chromatographic run time is less than 2 min.

Azasteroids↗

PubMed1991

The protein composition of reconstituted 30S ribosomal subunits: the effects of single protein omission.

Using reverse phase HPLC, we have been able to quantify the protein compositions of reconstituted 30S ribosomal subunits, formed either with the full complement of 30S proteins in the reconstitution mix or with a single protein omitted. We denote particles formed in the latter case as SPORE (single protein omission reconstitution) particles. An important goal in 30S reconstitution studies is the formation of reconstituted subunits having uniform protein composition, preferably corresponding to one copy of each protein per reconstituted particle. Here we describe procedures involving variation of the protein:rRNA ratio that approach this goal. In SPORE particles the omission of one protein often results in the partial loss in uptake of other proteins. We also describe procedures to increase the uptake of such proteins into SPORE particles, thus enhancing the utility of the SPORE approach in defining the role of specific proteins in 30S structure and function. The losses of proteins other than the omitted protein provide a measure of protein:protein interaction within the 30S subunit. Most of these losses are predictable on the basis of other such measures. However, we do find evidence for several long-range protein:protein interactions (S6:S3, S6:S12, S10:S16, and S6:S4) that have not been described previously.

Chromatography, High Pressure Liquid↗

PubMed1988

Incorporation of single dinitrophenyl-modified proteins into the 30 S subunit of Escherichia coli ribosomes by total reconstitution.

In this first of two consecutive papers, the main objective of which is to present a new approach to the systematic localization of individual proteins located in the Escherichia coli ribosome by immunoelectron microscopy, we describe the derivatization of several purified 30 S proteins (S12, S21, S14, S19, S18, S17) with 2,4-[3,5-3H]dinitrofluorobenzene at pH 7.4 and 8.4 and the uptake of each dinitrophenylated protein in place of the corresponding unmodified protein into totally reconstituted 30 S subunits. Reverse-phase high performance liquid chromatography is used to purify the proteins, to separate and characterize the products of 2,4-[3,5-3H]dinitrofluorobenzene modification, and to analyze the protein composition of the reconstituted subunits. The extent of dinitrophenyl (DNP) modification is estimated by both radioactivity and integrated peak areas, using dual wavelength monitoring at 214 and 360 nm. DNP derivatives of each of the six proteins are efficiently incorporated into reconstituting 30 S subunits. Incorporation of any of the six DNP-modified proteins does not interfere with binding of Phe-tRNA(Phe) in a poly(U)-dependent manner. This result, as well as data showing that unmodified protein competes with DNP-protein for uptake during reconstitution, provide evidence that each DNP-protein occupies the same position in 30 S subunit as does unmodified protein. In general, for a given protein, unmodified and/or less modified forms are incorporated in preference to more modified forms. Modification of protein S19 at pH 7.4 proceeds with selective formation of one derivative in high yield. Reverse-phase high performance liquid chromatography analysis of acid hydrolysates of a purified sample of this derivative, as well as of peptides derived from it by digestion with Staphylococcus aureus protease, show the N-terminal proline to be the predominant site of DNP-derivatization.

Amino Acids↗

PubMed1988

Immune electron microscopic localization of dinitrophenyl-modified ribosomal protein S19 in reconstituted Escherichia coli 30 S subunits using antibodies to dinitrophenol.

Escherichia coli small ribosomal subunits have been reconstituted from RNA and high performance liquid chromatography-purified proteins including protein S19 that had been modified at its amino-terminal proline residue with 1-fluoro-2,4-dinitrobenzene. As detailed in the accompanying paper (Olah, T. V., Olson, H. M., Glitz, D. G., and Cooperman, B. S. (1988) J. Biol. Chem. 263, 4795-4800), dinitrophenyl (DNP)-S19 was efficiently incorporated into the site ordinarily occupied by S19. Antibodies to DNP bound effectively to the reconstituted subunits and did not cause dissociation of the modified protein from the subunit. Electron microscopy of the immune complexes was used to localize the modified protein on the subunit surface. More than 95% of the antibody binding sites seen were consistent with a single location of protein S19 on the upper portion or head of the subunit, on the surface that faces the 50 S particle in a 70 S ribosome, and in an area relatively distant from the subunit platform. The S19 site is close to the region in which 30 S subunits are photoaffinity labeled with puromycin. Protein S19 is thus near protein S14 in the small subunit and in proximity to the peptidyl transferase center of the 70 S ribosome.

Antibodies↗

PubMedDate not supplied

Metabolism of 3-[2-(benzoxazol-2-yl)ethyl]-5-ethyl-6-methylpyridin-2 (1H)-one (L-696,229), an HIV-1 reverse transcriptase inhibitor, by rat liver slices and in humans.

Healthy subjects were administered single oral doses of 800 mg or 400 mg 3-[2-(benzoxazol-2-yl)ethyl]-5-ethyl-6-methylpyridin-2(1H)-o ne (L-696,229), a nonnucleoside inhibitor of the human immunodeficiency virus-type 1 (HIV-1) reverse transcriptase (RT). Plasma or urine samples were collected over a period of 48 hr. Pooled plasma (0.5-6 hr) and urine (0-24 hr) samples were analyzed by HPLC-UV and HIV-1 RT inhibition assay using poly rC.dG as a template primer. The parent compound and several common metabolites were detected in both samples. The metabolic profiles were also similar to those obtained from a rat liver slice incubation with [3H]L-696,229. The in vitro metabolites were identified by NMR and MS as 5 alpha-hydroxyethyl- (major), 5,6-dihydrodiol-, 6'-hydroxy-, 6-hydroxymethyl-, and 5-vinyl analogs, and a benzoxazole ring hydrolysis product. Most of the significant metabolites in human plasma and urine were found to be identical to the in vitro metabolites, as established by HPLC-UV and MS. Hydrolysis of the plasma and urine with beta-glucuronidase/sulfatase indicated the presence of significant amounts of conjugates of the parent compound and 5 alpha-hydroxyethyl metabolite. Most of the other primary metabolites were also present in conjugated forms, albeit in small quantities. In addition, two secondary metabolites were isolated and identified from the hydrolyzed urine as 5-acetyl-6'-hydroxy- and 5 alpha-hydroxyethyl-6-hydroxymethyl- analogs.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗

PubMedDate not supplied

Biotransformation of 5-chloro-3-phenylthioindole-2-carboxamide (L-734,005) in rhesus monkeys and rat liver microsomes to a potent HIV-1 reverse transcriptase inhibitor.

Rhesus monkeys were dosed orally with 10 mg/kg 5-chloro-3-phenylthioindole-2-carboxamide (L-734,005), a nonnucleoside human immunodeficiency virus type 1 (HIV-1) reverse transcriptase inhibitor, in polyethylene glycol 300. Plasma samples from these monkeys demonstrated greater bioactivity in an HIV-1 reverse transcriptase inhibition assay than anticipated from the parent compound concentrations as determined by an HPLC-UV assay. One major and three minor metabolites, as well as the parent compound, were detected in the plasma. One of the minor metabolites was determined to be several-fold more active, and the major metabolite one-half as active as the parent compound in the inhibition assay. Identical metabolites were formed during an incubation of L-734,005 with rat liver microsomes. The most active minor metabolite was identified as a sulfone analog (L-737,126) of the parent compound by NMR and MS analyses. The less active major metabolite and two relatively inactive minor metabolites were similarly identified as the sulfoxide, 4-hydroxythiophenyl and 6-hydroxyindole analogs of L-734,005. The synthetic sulfone analog was highly potent against HIV-1, with a 95% inhibitory concentration of 3.0 nM for the spread of virus infection in a cell culture.

Animals↗