Biomedical subjects

C L Chen

Publications and source records attributed to C L Chen.

At least 127 records · Page 7Linked to original sources

PubMed1999

11,12-Epoxyeicosatrienoic acid stimulates endogenous mono-ADP-ribosylation in bovine coronary arterial smooth muscle.

The role of endogenous ADP-ribosylation in mediating the activation of the Ca(2+)-activated K(+) channels was determined in bovine coronary arteries. Endogenous ADP-ribosylation was examined by incubating coronary arterial homogenates or lysates of cultured coronary arterial smooth muscle cells with [adenylate-(32)P]NAD. Four (32)P-labeled proteins were observed at 51, 52, 80, and 124 kDa in the homogenates and lysates. This reaction was enhanced by the addition of 11,12-epoxyeicosatrienoic acid (11,12-EET), a cytochrome P450-derived eicosanoid, and GTP to the incubation. By Western blot analysis, 42- and 70-kDa proteins were recognized by specific antibodies against ADP-ribosyltransferase in the coronary arterial homogenates and smooth muscle cell lysate but not in the lysate of endothelial cells. The 52-kDa acceptor protein of endogenous ADP-ribosylation comigrated with a protein ADP-ribosylated by cholera toxin and was recognized and immunoprecipitated by an anti-G(S)alpha antibody. These results suggest that G(S)alpha is one of several acceptors of the ADP-ribose moiety. As shown by the patch-clamp technique, 11,12-EET stimulated the activation of the K(+) channels in the smooth muscle cells, and this activation was completely blocked by novobiocin, vitamin K(1), 3-aminobenzamide, and m-iodobenzylguanidine, inhibitors of endogenous mono-ADP-ribosyltransferases. We conclude that endogenous mono-ADP-ribosyltransferases are present in smooth muscle from bovine coronary arteries. These enzymes transfer ADP-ribose to the cellular proteins such as G(S)alpha and may mediate intracellular signal transduction in coronary vascular smooth muscle. In the coronary circulation, the ADP-ribosylation signaling pathway may play an important role in mediating the activation of the K(+) channels induced by 11,12-EET.

8,11,14-Eicosatrienoic Acid↗

PubMed1999

Magnetic resonance of the hepatic veins with angular reconstruction: application in living-related liver transplantation.

BACKGROUND: Preoperative mapping of the hepatic venous system of the partial liver graft is indispensable to the success of living-related liver transplantation. We assessed the accuracy of magnetic resonance (MR) venography with angular reconstruction in depicting the tributaries of the middle hepatic vein and left hepatic vein in the donors, which was essential in graft retrieval and venoplasty. METHODS: Nineteen living-related liver transplantation donors underwent a pretransplantation survey, including sonography and MRI for hepatic venous evaluation. T1-weighted images were reconstructed manually, using the inferior vena cava as a fixed point for tilting to produce an oblique plane image where both the middle hepatic vein and left hepatic vein could be demonstrated draining into the inferior vena cava. The reconstructed images of the hepatic veins were compared with preoperative sonography, intraoperative sonography, and operative findings. RESULTS: Preoperative sonography and MR findings correlated well with the operative findings in the major hepatic veins. The MR venography of the ramification of the hepatic veins has an accuracy of 93%, the sonography, 84%. Sonography is slightly inferior in the evaluation of the hepatic vein in segment 4 and the left superior hepatic vein, with an accuracy of 73% and 67%, respectively. CONCLUSION: MR venography with angular reconstruction is accurate in depicting the complex distribution of the hepatic veins of the left liver, providing important information for decision making as to the cutting plane during graft retrieval and the method of venoplasty and anastomosis. Thus, unnecessary blood loss could be avoided and vascular complications could be prevented, as these conditions would be unacceptable for a healthy living donor. We propose that MR venography, a rapid and reliable technique, is an appropriate alternative examination or complementary modality to sonography in the pretransplantation evaluation of the living donor.

Adult↗

PubMed1999

Structure-activity relationships of naturally occurring and synthetic opioid tetrapeptides acting on locus coeruleus neurons.

Intracellular recording was used to study the effects of eight opioid tetrapeptides with similar amino acid sequences, namely endomorphin-1 (Tyr-Pro-Trp-Phe-NH2), endomorphin-2 (Tyr-Pro-Phe-Phe-NH2), morphiceptin (Tyr-Pro-Phe-Pro-NH2), hemorphin-4 (Tyr-Pro-Trp-Thr), Tyr-MIF-1 (Tyr-Pro-Leu-Gly-NH2), Tyr-W-MIF-1 (Tyr-Pro-Trp-Gly-NH2), TAPS (Tyr-D-Arg-Phe-Sar) and DALDA (Tyr-D-Arg-Phe-Lys-NH2), on neurons of the rat locus coeruleus, using a submerged brain slice preparation. All the tetrapeptides inhibited the spontaneous firing of all neurons of the locus coeruleus tested. Higher concentrations also caused hyperpolarization of the neurons and a reduction in input resistance. These inhibitory effects were rapidly and completely reversed by CTAP (D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2, a selective micro-opioid receptor antagonist). The IC50 of the opioid tetrapeptides, in terms of inhibition of spontaneous firing of locus coeruleus neurons, as compared to the concentrations which produced a 5-mV hyperpolarization (HC5 mV) were calculated, giving the same rank order of potency: TAPS (IC50 = 1.9 nM, HC5 mV = 3.4 nM) > endomorphin-1 (IC50 = 8.8 nM, HC5 mV = 22.1 nM) and endomorphin-2 (IC50 = 5.3 nM, HC5 mV = 16.1 nM)> DALDA (IC50 = 20 nM, HC5 mV = 143 nM) > morphiceptin (IC50 = 65 nM, HC5 mV = 335 nM) > Tyr-W-MIF-I (IC50 = 3.8 microM, HC5 mV = 6.7 microM) > hemorphin-4 (IC50 = 6.7 microM, HC5 mV = 36.9 microM) > Tyr-MIF-1 (IC50 = 37.5 microM, HC5 mV = 76.2 microM). Comparison of the ability of endomorphin-1 and endomorphin-2 to inhibit spontaneous firing based on single-cell recordings (n = 5) showed these two peptides to be equipotent. Based on these results, the structure-activity relationships of these opioid tetrapeptides are discussed herein.

Animals↗

PubMed1999

Quantitative high-performance liquid chromatographic method for pharmacokinetic studies of the potent mast cell inhibitor 4-(4'-hydroxyphenyl)amino-6,7-dimethoxyquinazoline (WHI-P131).

The novel quinazoline derivative 4-(4'-hydroxyphenyl)amino-6,7-dimethoxyquinazoline (WHI-P131) has recently been identified as a potent mast cell inhibitor capable of preventing IgE/antigen induced cutaneous as well as systemic fatal anaphylaxis in mice. Here we describe a sensitive high-performance liquid chromatography (HPLC)-based quantitative detection method for measurement of WHI-P131 levels in plasma as well as in target mast cells. The average extraction recovery for WHI-P131 was 88.4% for plasma and 75.7% for RBL-2H3 mast cell lysates. Good linearity (r>0.999) was observed throughout the concentration range of 0.1-20 microM in plasma and 0.01-5 nmol in 5 x 10(6) cells (0.5-238 microM per cell) for WHI-P131. Intra- and inter-assay variabilities were <7% and the lowest detection limit of WHI-P131 was 0.05 microM in plasma and 0.005 nmol in 5 million cells, respectively, at a signal-to-noise ratio of approximately 2. The practical utility of this new HPLC method was confirmed in a pilot pharmacokinetic study in BALB/c mice as well as in a cellular drug uptake and disposition study in RBL-2H3 mast cells. After intraperitoneal administration of a non-toxic 40 mg/kg bolus dose of WHI-P131, the estimated maximum plasma concentration was 92.7 microM, which is approximately 1-log higher than the effective in vitro mast cell inhibitory concentrations of WHI-P131. The drug absorption was rapid with an absorption half-life of only 2.9 min and the estimated time to reach the maximum plasma concentration was 8.3 min. WHI-P131 was cleared with an apparent systemic clearance rate of 2586 ml/h/kg and an elimination half-life of 1.8 h. An intracellular exposure level (AUC) of 55 microM x h was obtained after in vitro treatment of RBL-2H3 mast cells with WHI-P131 at a 33.6 microM final concentration in culture medium. The availability of the described quantitative HPLC detection method for WHI-P131 provides the basis for further development of WHI-P131 as an anti-allergic drug through detailed pharmacodynamic studies in preclinical animal models.

Animals↗

PubMed1999

Differential serine phosphorylation regulates IkappaB-alpha inactivation.

NF-kappaB is a ubiquitous transcription factor involved in the signal transduction mechanisms of the immune response, acute phase reactions, and viral infections. NF-kappaB proteins are retained in the cytoplasm by association with an inhibitor, termed IkappaB. Studies on the regulation of mammalian IkappaB-alpha have revealed that two amino-terminal conserved phosphoserines are the target sites of incoming signals. We report that the corresponding amino-terminal phosphoserines of avian IkappaB-alpha are phosphorylation targets leading to inactivation of IkappaB-alpha upon stimulation. In addition, we show differential roles for these two serines. Mutation of serine 40 to alanine blocks all stimuli tested (TNF-alpha, phorbol ester, and anti-CD3 and anti-CD28), leading to NF-kappaB activation, while mutation of serine 36 to alanine attenuates only certain transduced signals (PMA, TNF-alpha). These novel findings support the hypothesis that the amino-terminal phosphoserine residues of avian IkappaB-alpha differentially mediate NF-kappaB signal transduction pathways and activation by distinct signals, thereby resulting in the activation NF-kappaB.

Amino Acid Substitution↗

PubMed1999

Profile of cytokine expression in nasopharyngeal carcinomas: a distinct expression of interleukin 1 in tumor and CD4+ T cells.

Nasopharyngeal carcinoma (NPC) is an epithelial cancer that is causally associated with Epstein-Barr virus (EBV) infection. NPC tumor biopsies are characterized histopathologically by an abundant infiltration of nonmalignant lymphocytes. We analyzed the expression of various cytokines in NPC tissues to investigate the interaction of the infiltrating lymphocytes and tumor cells. Analysis using reverse transcriptase-PCR revealed the expression of a panel of cytokines in the NPC biopsies: interleukin (IL)-1alpha, IL-1beta, IL-2, IL-4, IL-5, IL-6, IL-10, IFN-gamma, tumor necrosis factor-alpha, transforming growth factor-beta, and IL-1 receptor types I and II. Elevated expression of IL-1alpha and IL-1beta was observed in primary tumors and NPC metastases compared to control tissues. Interestingly, this increased expression correlated with the EBV-encoded viral IL-10 transcript. To determine which cells were responsible for producing IL-1, we determined the cellular constituents of NPC biopsies by immunoflow cytometric analysis. On the basis of data from these analyses, the three major specific cell populations, epithelial cells, CD4+ T cells, and CD8+ T cells, were selected from five NPC tumors using specific, antibody-coated paramagnetic beads. Reverse transcriptase-PCR of RNA from these fractionated cells showed that transcripts of IL-1alpha and IL-1beta were present not only in the malignant epithelial cells but also in CD4+ T cells infiltrating the tumor, a finding confirmed by immunohistochemical staining. We hypothesize that the unusual synthesis of IL-1alpha and IL-1beta by EBV-positive epithelial cells as well as by CD4+ T cells might contribute to lymphocyte infiltration and/or tumor growth during NPC development.

Biopsy↗

PubMed1999

Quantitative high-performance liquid chromatography-based detection method for calphostin C, a naturally occurring perylenequinone with potent antileukemic activity.

Calphostin C is a potent inhibitor of protein kinase C and can induce Ca2+-dependent apoptosis in human ALL cells. Further development of calphostin C will require detailed pharmacodynamic studies in preclinical animal models. Therefore, we established a sensitive and accurate high-performance liquid chromatography (HPLC)-based quantitative detection method for the measurement of calphostin C levels in plasma. Extraction of calphostin C from plasma was performed by precipitation of plasma protein using acetonitrile and an aliquot of extracted supernatant was injected onto a Hewlett-Packard HPLC system constituting a 250x4 mm LiChrospher 100, RP-18 (5 microm) in conjunction with a 4x4 mm LiChrospher 100, RP-18 guard column (5 microm). The eluted compounds were detected by diode array detection set at a wavelength of 479 nm. Acetonitrile-water containing 0.1% trifluoroacetic acid and 0.1% triethylamine (70:30, v/v) was used as the mobile phase. The average extraction recovery from plasma was 97.3%. Good linearity (r>0.999) was observed throughout the concentration range of 0.05-40 microM for calphostin C in 50 microl of plasma. Intra- and inter-assay variabilities were less than 6% in plasma. The lowest detection limit of calphostin C in 50 microl plasma was 0.02 microM at a signal-to-noise ratio of approximately 3. The availability of this assay will now permit detailed pharmacodynamic and pharmacokinetic studies of calphostin C in vivo.

Animals↗

PubMed1999

Maternal smoking and Down syndrome: the confounding effect of maternal age.

Inconsistent results have been reported from studies evaluating the association of maternal smoking with birth of a Down syndrome child. Control of known risk factors, particularly maternal age, has also varied across studies. By using a population-based case-control design (775 Down syndrome cases and 7,750 normal controls) and Washington State birth record data for 1984-1994, the authors examined this hypothesized association and found a crude odds ratio of 0.80 (95% confidence interval 0.65-0.98). Controlling for broad categories of maternal age (<35 years, > or =35 years), as described in prior studies, resulted in a negative association (odds ratio = 0.87, 95% confidence interval 0.71-1.07). However, controlling for exact year of maternal age in conjunction with race and parity resulted in no association (odds ratio = 1.00, 95% confidence interval 0.82-1.24). In this study, the prevalence of Down syndrome births increased with increasing maternal age, whereas among controls the reported prevalence of smoking during pregnancy decreased with increasing maternal age. There is a substantial potential for residual confounding by maternal age in studies of maternal smoking and Down syndrome. After adequately controlling for maternal age in this study, the authors found no clear relation between maternal smoking and the risk of Down syndrome.

Adult↗

PubMed1999

T cell receptor gene deletion circles identify recent thymic emigrants in the peripheral T cell pool.

Progenitor cells undergo T cell receptor (TCR) gene rearrangements during their intrathymic differentiation to become T cells. Rearrangements of the variable (V), diversity (D), and joining (J) segments of the TCR genes result in deletion of the intervening chromosomal DNA and the formation of circular episomes as a byproduct. Detection of these extrachromosomal excision circles in T cells located in the peripheral lymphoid tissues has been viewed as evidence for the existence of extrathymic T cell generation. Because all of the T cells in chickens apparently are generated in the thymus, we have employed this avian model to determine the fate of the V(D)J deletion circles. In normal animals we identified TCR Vgamma-Jgamma and Vbeta-Dbeta deletion circles in the blood, spleen, and intestines, as well as in the thymus. Thymectomy resulted in the gradual loss of these DNA deletion circles in all of the peripheral lymphoid tissues. A quantitative PCR analysis of Vgamma1-Jgamma1 and Vbeta1-Dbeta deletion circles in splenic gamma delta and Vbeta1(+) alphabeta T cells indicated that their numbers progressively decline after thymectomy with a half-life of approximately 2 weeks. Although TCR deletion circles therefore cannot be regarded as reliable indicators of in situ V(D)J rearrangement, measuring their levels in peripheral T cell samples can provide a valuable index of newly generated T cells entering the T cell pool.

Animals↗

PubMed1999

Inflammatory pseudotumor of the liver in Kostmann's disease.

A case in which inflammatory pseudotumor of the liver (IPTL) seemed to complicate severe congenital neutropenia (Kostmann's disease) is reported. IPTL is a rare entity, especially in childhood. The exact etiology of this lesion is unknown, but it is generally regarded as a benign, reactive inflammatory condition. Based on 15 reported pediatric cases in the literature, the causes, diagnosis, and treatment of IPTL are discussed.

Child, Preschool↗

PubMed1999

Influence of genotypes at SAA1 and SAA2 loci on the development and the length of latent period of secondary AA-amyloidosis in patients with rheumatoid arthritis.

To examine whether polymorphism at the SAA loci is associated with the development of amyloid protein A (AA)-amyloidosis, we determined the genotypes at the SAA1 and SAA2 loci in 43 AA-amyloidosis patients (amyloidosis population) and 77 patients with rheumatoid arthritis (RA) who had been ill for less than 5 years (early RA population). We also compared the frequencies of the genotypes at the SAA1 locus among 90 Korean, 95 Taiwanese, and 103 Japanese healthy subjects. The frequencies of the gamma/gamma genotype and gamma alleles at the SAA1 locus were significantly higher in the amyloidosis population than in the early RA population (34.9% versus 7.8%, and 58.1% versus 33.8%, chi2 test P=0.0001). The frequencies of the gamma allele at the SAA1 locus in Koreans, Taiwanese, and Japanese were 41.6%, 35.6%, and 37.4%, respectively. The length of the latent period of AA-amyloidosis was significantly longer in the patients with smaller numbers of the gamma allele at the SAA1 locus (Spearman's correlation coefficient: -0.42, P<0.05). On the other hand, the mean C-reactive protein (CRP) level during 2 years prior to the diagnosis of AA-amyloidosis was significantly higher in the patients with larger numbers of the gamma allele at the SAA1 locus (Spearman's correlation coefficient: 0.34, P<0.05). No significant association was found between amyloidosis and polymorphism at the SAA2 locus. We postulate that the allele SAA1gamma renders an RA patient susceptible to amyloidosis, possibly by affecting the severity of inflammation in RA.

Adult↗

PubMed1999

Anterior ankle-foot orthosis effects on postural stability in hemiplegic patients.

OBJECTIVES: To evaluate the effects of an anterior ankle-foot orthosis (AFO) on static and dynamic postural stability in hemiplegic patients. DESIGN: A cross-sectional assessment of hemiplegic subjects with and without an AFO. SETTING: Outpatient department of a rehabilitation hospital. PATIENTS: A convenience sample of 24 subjects who had been prescribed an anterior AFO. OUTCOME MEASURES: Postural sway index and postural symmetry (body weight distribution through the affected leg) when standing were measured as static postural stability. Maximal balance range in anterior-posterior and lateral directions and the affected leg's weight bearing after weight shift to affected side were measured as dynamic postural stability. RESULTS: When wearing the anterior AFO, there was no significant difference and small effect size (r<0.3) in postural sway index (p = .35), postural symmetry (p = .21), and maximal balance range in anterior-posterior direction (p = .46). There was a significant improvement and large effect size (r>0.5) in lateral weight shifting (p<.01) and weight bearing through the affected leg after weight shifted to the affected side (p<.01). CONCLUSIONS: The significant effects of the anterior AFO in long-term hemiplegic patients were on lateral weight shifting and weight bearing through affected leg after weight shifted to the affected side. Postural sway, postural symmetry, and anterior-posterior weight shifting were not significantly affected.

Adult↗

PubMed1999

WHI-05, a novel bromo-methoxy substituted phenyl phosphate derivative of zidovudine, is a dual-action spermicide with potent anti-HIV activity.

Heterosexual transmission of HIV to women is the fastest-growing mode of transmission. In a systematic effort to develop a microbicide capable of preventing HIV transmission as well as providing fertility control, novel phenyl phosphate derivatives of 3'-azido-3'-deoxythymidine (zidovudine, ZDV) have been identified that exhibit potent anti-HIV and spermicidal activities. This study reports the synthesis, characterization, and preclinical formulation of compound WHI-05, 5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-methoxyphenyl) methoxyalaninyl phosphate. The anti-HIV activities of WHI-05 and ZDV were compared by measuring p24 antigen production and reverse transcriptase activity as markers of viral replication using human peripheral blood mononuclear cells (PBMC) infected with both ZDV-sensitive and ZDV-resistant strains of HIV. The sperm immobilizing activity (SIA) of WHI-05 was compared with that of ZDV and nonoxynol-9 (N-9) by computer-assisted sperm analysis (CASA). The effect of WHI-05 on sperm membrane integrity was examined by high resolution, low voltage scanning electron microscopy (HR-LVSEM). The in vitro cytotoxicity profile of WHI-05 versus N-9 were compared using normal human vaginal, ectocervical, and endocervical epithelial cells. The in vivo vaginal tolerance, absorption, and toxicity of a 2% WHI-05 gel-microemulsion was tested in the rabbit. Whereas ZDV displayed potent anti-HIV activity but lacked SIA, WHI-05 elicited both potent anti-HIV activity and SIA. WHI-05 inhibited the replication of ZDV-sensitive as well as ZDV-resistant strains of HIV in PBMC. CASA combined with HR-LVSEM demonstrated that WHI-05-induced SIA was not associated with membrane damage. Unlike, N-9, the spermicidal activity of WHI-05 was not associated with cytotoxicity to reproductive tract epithelial cells. Repetitive intravaginal application of a 2% WHI-05 gel-microemulsion did not damage the vaginal epithelium or cause local inflammation in the rabbit model. As a potent anti-HIV agent that has spermicidal activity and is devoid of mucosal toxicity, WHI-05 shows a unique clinical potential to become the active ingredient for a vaginal contraceptive for women who are at high risk for acquiring HIV by heterosexual vaginal transmission.

Animals↗

PubMed1999

Safrole-induced oxidative damage in the liver of Sprague-Dawley rats.

Safrole is a weak hepatocarcinogen, and its carcinogenic effect has been linked to the formation of stable safrole DNA adducts. In this study, we tested whether safrole also induces oxidative damages in Sprague-Dawley rats. By single i.p. injection, safrole dose-dependently induced the formation of hepatic lipid hydroperoxides (LHP) and 8-hydroxy-2'-deoxyguanosine (8-OH-dG). The safrole-induced LHP reached peak level on day 3 and gradually returned to the basal level on day 15. On the other hand, 8-OH-dG levels from the similarly treated rats peaked on day 5 and returned to basal level on day 15. Safrole also dose-dependently induced serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities. We also examined the protective effect of vitamin E, deferoxamine and N-acetylcysteine against the safrole-induced oxidative damage. N-Acetylcysteine, the precursor of glutathione, exerted the greatest protective effect among the three antioxidants tested. In contrast, buthionine sulfoximine, the glutathione synthesis inhibitor, enhanced the safrole-induced oxidative damage, as evidenced by the elevation of LHP and 8-OH-dG levels on day 3 (P<0.05). These findings demonstrate that safrole treatment induces oxidative damage in rat hepatic tissue, and glutathione plays an important protective role. This oxidative damage may be involved in the hepatocarcinogenic effect of safrole.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1999

Characterization of residual lignin after SO(2)-catalyzed steam explosion and enzymatic hydrolysis of Eucalyptus viminalis wood chips.

The lignin component found in both water insoluble (WI) and water and alkali insoluble (WIA) fractions derived from SO(2)-impregnated steam-exploded eucalyptus chips (SEE) was isolated and characterized. Dioxane lignins with a sugar content lower than 2% (w/w) were obtained after each material was treated with commercial cellulases. The C9 formulas of both SEE-WI and SEE-WIA dioxane lignins were C(9)H(6.83)N(0.04)O(2.24)(OCH(3))(1.21)(OH(aro))(0.56)(OH(ali))(0. 77) and C(9)H(8.65)N(0.29)O(1.97)(OCH(3))(0.90)(OH(aro))(0. 46)(OH(ali))(1.02), respectively. The weight-average molecular weight (M(w)) of the SEE-WI lignin corresponded to 3.85 kDa, whereas the SEE-WIA lignin had an M(w) of 3.66 kDa for the same polydispersity of 2.4. The SEE-WIA lignin was shown to be more thermally stable than the SEE-WI lignin, requiring temperatures in the range of 520 degrees C for complete degradation. FTIR and (1)H NMR analyses of both untreated and peracetylated lignin fractions showed that (a) the alkali insoluble lignin contained a relatively higher degree of substitution in aromatic rings per C9 unit and that (b) alkaline extraction removed lignin fragments containing appreciable amounts of phenolic hydroxyl groups.

Cellulase↗

PubMed1999

Evaluation of the pharmacokinetic features and tissue distribution of the potent nonnucleoside inhibitor of HIV-1 reverse transcriptase, N-[2-(2-fluorophenethyl)]-N'-[2-(5-bromopyridyl)]-thiourea (HI-240) with an analytical HPLC method.

PURPOSE: The purpose of the present study was to examine the pharmacokinetic features and tissue distribution of N-[2-(2-fluorophenethyl)]-N'-[2-(5-bromopyridyl)]-thiourea (HI-240), a novel non-nucleoside inhibitor of HIV reverse transcriptase with potent anti-viral activity against AZT-sensitive as well as multidrug-resistant HIV-1 strains. METHODS: A sensitive and accurate high performance liquid chromatography (HPLC)-based quantitative detection method was established to measure concentrations of HI-240 in pharmacokinetic studies. The plasma concentration-time data were modeled by using the WinNonlin program to estimate the pharmacokinetic parameter values. RESULTS: HI-240 had an elimination half-life of 78.3 +/- 2.0 min after i.v. administration and 196.8 +/- 3.1 min after i.p. administration. The systemic clearance of HI-240 was 2194 +/- 61 ml/h/kg after i.v. administration and 9339 +/- 1160 ml/h/kg after i.p. administration. Following i.v. injection, HI-240 rapidly distributed to and accumulated in multiple tissues with particularly high accumulation in adipose tissue, adrenal gland, and uterus+ovary. The concentration of HI-240 in brain tissue was comparable to that in the plasma, indicating that HI-240 easily crosses the blood-brain-barrier. Following i.p. injection, HI-240 was rapidly absorbed with a t1/2ka and a tmax values of less than 10 min. Following oral administration, HI-240 was absorbed with a t1/2ka of 4.2 +/- 1.1 min and a tmax of 95.1 +/- 25.1 min. The intraperitoneal bioavailability was estimated at 23.5%, while the oral bioavailability was only 1%. CONCLUSIONS: The HPLC-based accurate and precise analytical detection method and pilot pharmacokinetic studies described herein provide the basis for advanced preclinical pharmacodynamic studies of HI-240. The ability of HI-240 to distribute rapidly and extensively into extravascular compartments and easily cross the blood-brain barrier represent significant pharmacokinetic advantages over AZT.

Administration, Oral↗

PubMed1999

Pharmacokinetics and biologic activity of the novel mast cell inhibitor, 4-(3-hydroxyphenyl)-amino-6,7-dimethoxyquinazoline in mice.

PURPOSE: The purpose of the present study was to examine the pharmacodynamic and pharmacokinetic features of the novel mast cell inhibitor 4-(3'-Hydroxyphenyl)-amino-6,7-dimethoxyquinazoline (WHI-P180) in mice. METHODS: A high performance liquid chromatography (HPLC)-based quantitative detection method was used to measure plasma WHI-P180 levels in mice. The plasma concentration-time data was fit to a single compartment pharmacokinetic model by using the WinNonlin program to calculate the pharmacokinetic parameters. A cutaneous anaphylaxis model was used to examine the pharmacodynamic effects of WHI-P180 on anaphylaxis-associated vascular hyperpermeability. RESULTS: The elimination half-life of WHI-P180 in CD-1 mice (BALB/ c mice) following i.v., i.p., or p.o. administration was less than 10 min. Systemic clearance of WHI-P180 was 6742 mL/h/kg in CD-I mice and 8188 mL/h/kg in BALB/c mice. Notably, WHI-P180, when administered in two consecutive nontoxic i.p. bolus doses of 25 mg/kg, inhibited IgE/antigen-induced vascular hyperpermeability in a well-characterized murine model of passive cutaneous anaphylaxis. CONCLUSIONS: WHI-P180 is an active inhibitor of IgE-mediated mast cell responses in vitro and in vivo. Further preclinical characterization of WHI-P180 may improve the efficacy of WHI-P180 in vivo and provide the basis for design of effective treatment and prevention programs for mast cell mediated allergic reactions.

Animals↗

PubMed1999

Pharmacokinetic features and metabolism of calphostin C, a naturally occurring perylenequinone with antileukemic activity.

PURPOSE: To examine the pharmacokinetic features and metabolism of calphostin C, a naturally occurring perylenequinone with potent antileukemic activity. METHODS: HPLC-based quantitative detection methods were used to measure calphostin C levels in lysates of leukemic cells and in plasma of mice treated with calphostin C. The plasma concentration-time data were analyzed using the WinNonlin program. In vitro esterases and a microsome P450 preparation in conjunction with a LC-MS(API-EI) system were used to study the metabolism of calphostin C. RESULTS: An intracellular exposure level (AUC0-6h) of 257 microM x h was achieved after in vitro treatment of NALM-6 cells with calphostin C at a 5 microM final concentration in culture medium. After intraperitoneal (i.p.) injection of a 40 mg/kg nontoxic bolus dose of calphostin C, the estimated Cmax was 2.9 microM, which is higher than the effective in vitro concentration of calphostin C against leukemic cells. Drug absorption after i.p. administration was rapid with an absorption half-life of 24.2 min and the estimated t(max) was 63.0 min. Calphostin C was cleared with an elimination half-life of 91.3 min. An inactive and smaller metabolite (calphostin B) was detected in plasma of calphostin C-treated mice with a t(max) of 41.3 min. Esterase (but not P450) treatment of calphostin C in vitro yielded an inactive metabolite (calphostin B) of the same size and elution profile. CONCLUSIONS: Target plasma calphostin C concentrations of potent antileukemic activity can be reached in mice at nontoxic dose levels. This pilot pharmacokinetic study of calphostin C combined with the availability of the described quantitative HPLC method for its detection in cells and plasma provide the basis for future preclinical evaluation of calphostin C and its potential as an anti-leukemic drug.

Animals↗