Synthesis and in vitro antitumor activity of oligonucleotide-tethered and related platinum complexes

Three classes of hydroxy-tethered platinum(II) complexes have been synthesized from K(2)PtCl(4) and appropriate amino alcohols. A sequence of selective oxidation and hydrolysis has been developed to prepare hydroxy-tethered platinum(IV) complexes. A novel procedure for the synthesis of amminetrichloroplatinate(II) anion has been generated and used to synthesize a number of monohydroxy-tethered nonchelating platinum complexes. These tethered platinum complexes, including hydroxy-tethered, phosphoramidite-tethered, and monodeoxyribonucleotide-tethered platinum(II) and -(IV) complexes, have been examined in vitro for antitumor activity in both leukemia and ovarian cancer cell lines. Activity of some of these complexes was similar to cis-platin, and most of them showed much better potency than carboplatin. We observed an interesting structure-activity correlation for platinum(II) complexes for both PA-1 and SK-OV-3 ovarian cancer cell lines. However, platinum(IV) complexes showed much more diversified response among cancer cell lines studied. We observed enhanced selectivity among different cancer cell lines for some agents. The most promising is the monodeoxyribonucleotide-tethered platinum(IV) complex, which is the first analogue of the conjugates between a platinum fragment and monodeoxyribonucleotides, showing antitumor activity and selectivity among the cell lines. Finally, the p53 status of the cells appears to contribute to the effectiveness of these agents in that cells harboring wild-type p53 appear to be more sensitive to these agents.

Biotransformation of D-limonene to (+) trans-carveol by toluene-grown Rhodococcus opacus PWD4 cells

The toluene-degrading strain Rhodococcus opacus PWD4 was found to hydroxylate D-limonene exclusively in the 6-position, yielding enantiomerically pure (+) trans-carveol and traces of (+) carvone. This biotransformation was studied using cells cultivated in chemostat culture with toluene as a carbon and energy source. The maximal specific activity of (+) trans-carveol formation was 14.7 U (g of cells [dry weight])(-1), and the final yield was 94 to 97%. Toluene was found to be a strong competitive inhibitor of the D-limonene conversion. Glucose-grown cells did not form any trans-carveol from D-limonene. These results suggest that one of the enzymes involved in toluene degradation is responsible for this allylic monohydroxylation. Another toluene degrader (Rhodococcus globerulus PWD8) had a lower specific activity but was found to oxidize most of the formed trans-carveol to (+) carvone, allowing for the biocatalytic production of this flavor compound.

Purine analogs as CDK enzyme inhibitory agents: a survey and QSAR analysis

Characterization of the cell cycle has introduced CDKs and other proteins as possible targets for inhibition of cell proliferation, such as, CDK1 and CDK2, whose inhibition may be useful in the treatment of proliferative disorders. Structure-activity analyses have been instrumental in the design and discovery of potent CDK inhibitors, such as purine analogs, which have increased in potency from the micromolar to the nanomolar level. X-ray crystallography and molecular modeling have provided evidence that these compounds act on the CDK target enzyme. Selected CDK inhibitors have successfully entered clinical trials. Further characterization of the cell cycle to identify molecular targets to inhibit cell proliferation, QSAR and SAR studies, and clinical trials may expedite the development of CDK inhibitors for therapeutic use. The ultimate goal of these studies is to determine whether specific CDKs, CDK1 or CDK2, are enzymes essential to cell proliferation that can be targeted for treatment of proliferative disorders. CDK1 and CDK2 are viable molecular targets for cancer therapies based on isolated-enzyme inhibition by CDK inhibitors, successful clinical trials of CDK1 and CDK2 inhibitors, and x-ray crystallographic confirmation of CDK inhibitors binding to the putative target enzyme active site. It is now reported that CDK1 inhibitory activities of purine analogs correlate with the physiochemical parameters of purine analogs. Enzyme inhibition [1-5], clinical trials (see Tab. 1), x-ray crystallographic [4, 6, 7] and QSAR correlation studies are evidence that specific CDK1 and/or CDK2 inhibitors are potentially useful agents for various cell-proliferation disorders. A brief overview of the cell cycle precedes a literature review of clinical applications of CDK inhibitors, followed by a new QSAR study, and a SAR and molecular modeling discussion.

Caspase-dependent cytosolic release of cytochrome c and membrane translocation of Bax in p53-induced apoptosis

Activation of p53 induces apoptosis in various cell types. However, the mechanism by which p53 induces apoptosis is still unclear. We reported previously that the activation of a temperature-sensitive mutant p53 (p53(138Val)) induced activation of caspase 3 and apoptosis in Jurkat cells. To elucidate the pathway linking p53 and downstream caspases, we examined the activation of caspases 8 and 9 in apoptotic cells. The results showed that both caspases were activated during apoptosis as judged by the appearance of cleavage products from procaspases and the caspase activities to cleave specific fluorogenic substrates. The significant inhibition of apoptosis by a tetrapeptide inhibitor of caspase 8 and caspase 9 suggested that both caspases are required for apoptosis induction. In addition, the membrane translocation of Bax and cytosolic release of cytochrome c, but not loss of mitochondrial membrane potential, were detected at an early stage of apoptosis. Moreover, Bax translocation, cytochrome c release, and caspase 9 activation were blocked by the broad-spectrum caspase inhibitor, Z-VAD-fmk and the caspase 8-preferential inhibitor, Ac-IETD-CHO, suggesting that the mitochondria might participate in apoptosis by amplifying the upstream death signals. In conclusion, our results indicated that activation of caspase 8 or other caspase(s) by p53 triggered the membrane translocation of Bax and cytosolic release of cytochrome c, which might amplify the apoptotic signal by activating caspase 9 and its downstream caspases.

Transcellular signaling and pharmacological modulation of thrombin-induced production of plasminogen activator inhibitor-1 in vascular smooth muscle cells

Thrombin formation is increased at the sites of vascular injury. Previous studies by our group and other groups indicated that the generation of plasminogen activator inhibitor-1 (PAI-1), the major physiological inhibitor for plasminogen activators, from cultured vascular smooth muscle cells (SMC) is elicited by thrombin. The present study demonstrates that the thrombin receptor, pertussis toxin-sensitive G protein, genistein-sensitive tyrosine kinase, phospholipase C, and protein kinase C may be involved in thrombin-induced PAI-1 production in cultured baboon aortic SMC. Forskolin and 8-bromo-cyclic AMP inhibited thrombin-induced PAI-1 production in cultured SMC. Treatment with hirulog-1, a synthetic thrombin receptor inhibitor, suppressed thrombin-induced PAI-1 generation at mRNA and protein levels in SMC. The results of the present study suggest that transmembrane receptor and multiple signal transduction systems are involved in thrombin-induced increase in PAI-1 transcription in vascular SMC. The production of PAI-1 stimulated by thrombin in vascular SMC may be pharmacologically modulated by thrombin receptor inhibitor.

A simplified method to prepare PCR template DNA for screening of transgenic and knockout mice

Polymerase chain reaction (PCR) amplification of DNA is the most widely used technique for screening of large numbers of genetically engineered transgenic or knockout mice (Mus musculus). In this report, we present a new DNA preparation procedure for running diagnostic PCR. In this procedure, mouse ear tissue was used directly for PCR after the tissue underwent brief digestion in a solution containing only proteinase K. Using this method, we have successfully screened several lines of single, double, and triple transgenic and knockout mice. The results are reliable and reproducible. The advantage of this new method is that DNA purification by organic extraction or isolation kit was omitted. DNA purification is the limiting factor in terms of time and money when screening transgenic and knockout mice by PCR. In addition, using ear instead of tail tissue can reduce distress of animals because the samples can be obtained when the mice are labeled by ear punch.

[Construction of luciferase reporter plasmid which is under the control of dioxin-responsive enhancers]

To improve the bio-detection of dioxin-type chemicals, we constructed a plasmid containing reporter under the control of dioxin-responsive enhancer. After connected the enhancer from the plasmid pHAV with the MMTV promoter of the plasmid pCatM, the connected segment was linked with the luciferase vector. Then the recombinant plasmid was transfected to the HepG2 human hepatoma cell line, and the luciferase activity was induced by 2,3,7,8-TCDD. The result suggested that expression of the recombinant luciferase was controlled by the dioxin-responsive enhancer, and there were a linear relationship between the activity of luciferase and certain range of 2,3,7,8-TCDD concentration. It is promising that the transfected cell line could be used for rapid screen and semi quantitation of dioxin-type chemicals, and a standard and routine method for the detection of dioxin-type chemicals by this recombinant plasmid is being under way.

Hirulog-like peptide reduces balloon catheter injury induced neointima formation in rat carotid artery without increase in bleeding tendency

Vascular restenosis is one of the major concerns for the management of coronary artery disease using therapeutic vascular procedures. Treatments with thrombin-specific inhibitors, hirudin or hirulog-1, reduced ischemic events in coronary artery disease patients. Early started and prolonged infusions of these thrombin inhibitors partially prevented balloon catheter injury induced restenosis or neointima formation in experimental animal models, but increased the bleeding tendency. Hirulog-like peptide (HLP) was rationally designed to enhance the inhibition of the binding of thrombin to its receptor with less interruption of coagulation activity in comparison to hirulog-1. A single infusion of HLP for 4 h started 0.5 h before balloon catheter injury reduced neointima formation by 36% in rat carotid artery compared to vehicle controls. Tail bleeding time and activated partial thromboplastin time during HLP infusion were not significantly different from vehicle controls, but were significantly shorter than during heparin or hirulog-1 infusion. HLP treatment attenuated the expression of platelet-derived growth factor in the neointima of injured arteries. HLP also inhibited thrombin-induced thymidine incorporation in cultured baboon aortic smooth muscle cells. The findings suggest that HLP may substantially inhibit balloon catheter injury induced neointima formation without noticeable increase in bleeding tendency in rats. The inhibition by HLP of the expression of platelet-derived growth factor and of the smooth muscle cell proliferation in the vascular wall potentially contributes to the preventive effect of the new thrombin inhibitor on injury-induced neointima formation in the vascular wall.

Hepatitis B virus (HBV) virion and covalently closed circular DNA formation in primary tupaia hepatocytes and human hepatoma cell lines upon HBV genome transduction with replication-defective adenovirus vectors

Hepatitis B virus (HBV), the causative agent of B-type hepatitis in humans, is a hepatotropic DNA-containing virus that replicates via reverse transcription. Because of its narrow host range, there is as yet no practical small-animal system for HBV infection. The hosts of the few related animal viruses, including woodchuck hepatitis B virus and duck hepatitis B virus, are either difficult to keep or only distantly related to humans. Some evidence suggests that tree shrews (tupaias) may be susceptible to infection with human HBV, albeit with low efficiency. Infection efficiency depends on interactions of the virus with factors on the surface and inside the host cell. To bypass restrictions during the initial entry phase, we used recombinant replication-defective adenovirus vectors, either with or without a green fluorescent protein marker gene, to deliver complete HBV genomes into primary tupaia hepatocytes. Here we show that these cells, like the human hepatoma cell lines HepG2 and Huh7, are efficiently transduced by the vectors and produce all HBV gene products required to generate the secretory antigens HBsAg and HBeAg, replication-competent nucleocapsids, and enveloped virions. We further demonstrate that covalently closed circular HBV DNA is formed. Therefore, primary tupaia hepatocytes support all steps of HBV replication following deposition of the genome in the nucleus, including the intracellular amplification cycle. These data provide a rational basis for in vivo experiments aimed at developing tupaias into a useful experimental animal system for HBV infection.

Disialoganglioside GD3 is selectively expressed by developing and mature human mast cells

BACKGROUND

Disialoganglioside GD3 is expressed on the surface of selected cell types. Anti-GD3 mAb administered to human subjects with malignant melanoma produces signs and symptoms of immediate hypersensitivity reactions.

OBJECTIVE

The expression of GD3 by human mast cells was assessed during mast cell development in vitro and in samples of lung and skin.

METHODS

GD3 on tissue- and in vitro-derived mast cells was analyzed after double labeling of cells for tryptase (G3 mAb) or Kit (YB5.B8 mAb) and GD3 (R24 mAb). Glycolipids in extracts of fetal liver-derived mast cells were examined by using high-performance thin-layer chromatography.

RESULTS

Flow cytometry showed that the percentage of GD3+ cells increased in parallel to Kit+ cells during the recombinant human stem cell factor-dependent development of fetal liver-derived mast cells. Double-labeling experiments showed that GD3+ cells were also surface Kit+ and granule tryptase positive, identifying them as mast cells in preparations of lung-, skin-, fetal liver-, and cord blood-derived cells. The major acidic glycolipid detected was NeuAcalpha2-8NeuAcalpha2-3Galbeta1-4Glcbeta1-1'Cer (GD3). Among peripheral blood leukocytes, only basophils and about 10% of the T cells were labeled with anti-GD3 mAb. Anti-GD3 mAb-conjugated magnetic beads were used to purify mast cells to greater than 90% purity from dispersed skin cells enriched to approximately 12% purity by means of density-dependent sedimentation but were less proficient for dispersed human lung mast cells, most likely because of other cell types that express GD3.

CONCLUSION

GD3 is expressed on the surface of developing human mast cells in parallel to tryptase in secretory granules and, like Kit, can serve as a target for their enrichment by immunoaffinity techniques.

Neurological abnormalities in a knock-in mouse model of Huntington's disease

Mice representing precise genetic replicas of Huntington's disease (HD) were made using gene targeting to replace the short CAG repeat of the mouse Huntington's disease gene homolog (HDH:) with CAG repeats within the length range found to cause HD in humans. Mice with alleles of approximately 150 units in length exhibit late-onset behavioral and neuroanatomic abnormalities consistent with HD. These symptoms include a motor task deficit, gait abnormalities, reactive gliosis and the formation of neuronal intranuclear inclusions predominating in the striatum. This model differs from previously described HDH: knock-ins by its method of construction, longer repeat length and more severe phenotype. To our knowledge, this is the first knock-in mouse model of HD to show increased glial fibrillary acidic protein immunoreactivity in the striatum, suggesting that these mice have neuronal injury similar to that found early in the course of HD. These mice will serve as useful reagents in experiments designed to reveal the molecular nature of neuronal dysfunction underlying HD.

Efficacy and effect of SI17 therapy on pancreatic polypeptide in vascular and tension-type headache

BACKGROUND AND PURPOSE

Vascular and tension-type headache is most commonly encountered, and SI17 therapy has been tested to treat headache with good results. The efficacy of SI17 therapy for vascular and tension-type headache was compared and the effect of SI17 therapy on pancreatic polypeptide (PP) was studied.

MATERIALS AND METHODS

29 cases of vascular headache (20 cases in acute attack during the trial) and 27 cases of tension-type headache (19 cases in acute attack) were enrolled in the study. Plasma PP level before and 4th day after treatment was measured by radioimmunoassay.

RESULTS

SI17 therapy is better for the treatment of vascular headache. Vascular headache with higher PP level and tension-type headache with normal PP level had good therapeutic results.

CONCLUSION

The clinical efficacy is better for vascular headache with the increase of vagus tension and for tension-type headache with normal vagus tension.

Intracellular vitamin D binding proteins: novel facilitators of vitamin D-directed transactivation

Previously recognized intracellular proteins with an affinity for vitamin D metabolites include the vitamin D receptor and the cytochrome P-450-based vitamin D metabolizing mixed-function oxidases. We recently characterized a third set of high-capacity, intracellular vitamin D binding proteins (IDBPs) in the inducible heat shock protein-70 (hsp-70) family. Here we report the cloning and expression of cDNAs coding for two IDBPs. The full-length cDNAs for IDBP-1 and IDBP-2 demonstrated 95% and 94% nucleotide homology, respectively, with the cDNAs for human constitutively expressed heat shock protein 70 (hsc-70) and hsp-70. Transient expression of the IDBP cDNAs in a vitamin D-responsive primate cell line increased extractable 25-hydroxylated vitamin D metabolite-IDBP-binding 25-fold. Transfection experiments also demonstrated that the majority of the constitutively expressed 25-hydroxylated vitamin D metabolite binding activity was attributable to expression of the hsc-70-related IDBP-1 and that metabolite binding activity sublocalized to the highly conserved ATP-binding/ATPase domain of hsp-70s. Stable overexpression of IDBP-1 in wild-type cells enhanced vitamin D-directed responsiveness of endogenous vitamin D-24-hydroxylase, osteopontin, and osteocalcin genes by several-fold over that observed in cells transfected with an empty vector. These results suggest that IDBP-1 facilitates the intracellular localization of active vitamin D metabolites and vitamin D receptor-mediated transactivation.

Glycation amplifies lipoprotein(a)-induced alterations in the generation of fibrinolytic regulators from human vascular endothelial cells

Increased lipoprotein(a) [Lp(a)] in plasma is an independent risk factor for premature cardiovascular diseases. The levels of glycated Lp(a) are elevated in diabetic patients. The present study demonstrated that glycation enhanced Lp(a)-induced production of plasminogen activator inhibitor-1 (PAI-1), and further decreased the generation of tissue-type plasminogen activator (t-PA) from human umbilical vein endothelial cells (HUVEC) and human coronary artery EC. The levels of PAI-1 mRNA and its antigen in the media of HUVEC were significantly increased following treatments with 5 microgram/ml of glycated Lp(a) compared to equal amounts of native Lp(a). The secretion and de novo synthesis of t-PA, but not its mRNA level, in EC were reduced by glycated Lp(a) compared to native Lp(a). Treatment with aminoguanidine, an inhibitor for the formation of advanced glycation end products (AGEs), during glycation normalized the generation of PAI-1 and t-PA induced by glycated Lp(a). Butylated hydroxytoluene, a potent antioxidant, inhibited native and glycated Lp(a)-induced changes in PAI-1 and t-PA generation in EC. The results indicate that glycation amplifies Lp(a)-induced changes in the generation of PAI-1 and t-PA from venous and arterial EC. This may attenuate fibrinolytic activity in blood circulation and potentially contributes to the increased incidence of cardiovascular complications in diabetic patients with hyperlipoprotein(a). EC-mediated oxidative modification and the formation of AGEs may be implicated in glycated Lp(a)-induced alterations in the generation of fibrinolytic regulators from vascular EC.

Impact of antioxidants and HDL on glycated LDL-induced generation of fibrinolytic regulators from vascular endothelial cells

Hyperglycemia and dyslipoproteinemia are biochemical markers of diabetes mellitus (DM). Elevated levels of plasminogen activator inhibitor-1 (PAI-1) with and without reduction of tissue plasminogen activator (tPA) in plasma have been frequently found in patients with DM. Our previous studies indicated that glycation enhances low density lipoprotein (LDL)-induced production of PAI-1 and further decreases tPA generation in vascular endothelial cells (ECs). The present study demonstrated that treatment with antioxidants, butylated hydroxytoluene or vitamin E, blocked native LDL- and glycated LDL-induced changes in PAI-1 and tPA generation in ECs. Native or glycated high density lipoprotein (HDL) did not significantly alter tPA generation in ECs. Glycated but not native HDL (>/=100 microg/mL) moderately increased PAI-1 release from ECs. Cotreatment with native or glycated HDL inhibited LDL-induced or glycated LDL-induced changes in PAI-1 and tPA generation in ECs. The abundance of conjugated dienes was increased in glycated or EC-modified LDL. Treatment with butylated hydroxytoluene, vitamin E, or HDL reduced the abundance of conjugated dienes in glycated or EC-modified LDL. The effects of antioxidants and HDL on LDL-induced or its glycated LDL-induced changes in the generation of PAI-1 and tPA were also found in cultured human coronary artery ECs. The findings of the present study suggest that antioxidants and HDL may attenuate native LDL- or glycated LDL-induced changes in the generation of fibrinolytic regulators from vascular ECs, which possibly results from their inhibition on the lipid peroxidation of LDL particles. Treatment with antioxidants or hypolipidemic agents potentially improves fibrinolytic activity and reduces thrombotic tendencies in patients with DM.

Heme: a regulator of rat hepatic tryptophan 2,3-dioxygenase?

The hepatic cytosolic hemoprotein tryptophan 2,3-dioxygenase (TDO) is the rate-limiting enzyme in tryptophan catabolism and thus plays a key role in regulating the physiological flux of tryptophan into relevant metabolic pathways. The TDO protein is induced by corticosteroids such as dexamethasone (DEX) and is stabilized by its prosthetic heme. In rats, acute chemically induced hepatic heme depletion reduces the functional hepatic TDO levels to 25-30% of basal levels within 1 h, and this decrease persists beyond 28 h of heme depletion at which time only 25-30% of the protein is available for heme incorporation. Since this could stem from impaired de novo synthesis and/or instability of the newly synthesized apoTDO protein in the absence of heme, we examined the specific role of heme in these events in a previously validated rat model of acute hepatic heme depletion triggered by the P450 suicide substrate 3, 5-dicarbethoxy 2,6-dimethyl-4-ethyl-1,4-dihydropyridine. We now show that exogenous heme can reverse the functional impairment of the enzyme observed during hepatic heme depletion and fully restore the impaired DEX-mediated induction of the enzyme to normal. Furthermore, through Northern/slot blot analyses coupled with nuclear run-on studies, we now document that this heme regulation of TDO is exerted primarily at the transcriptional level. Immunoblotting analyses also reveal corresponding changes in the TDO protein, thereby establishing that heme is necessary for DEX-inducible TDO mRNA transcription and subsequent translation. Thus, the TDO gene may contain heme-regulatory elements in addition to the reported glucocorticoid-responsive elements. Together, these findings suggest that clinically, hepatic heme deficiency may enhance the tryptophan flux into synthetic (serotonergic) pathways, not only by depriving prosthetic heme for a functionally competent TDO hemoprotein, its primary catabolic enzyme, but also by impairing the de novo synthesis of this enzyme.

Locus-specific contig assembly in highly-duplicated genomes, using the BAC-RF method

Polyploidy, the presence of multiple sets of chromosomes that are similar but not identical, complicates both chromosome walking and assembly of sequence-ready contigs for many plant taxa including a large number of economically-significant crops. Traditional 'dot-blot hybridization' or PCR-based assays for identifying BAC clones corresponding to a mapped DNA landmark usually do not provide sufficient information to distinguish between allelic and non-allelic loci. A restriction fragment matching method using pools of BAC DNA in combination with dot-blots reveals the locus specificity of individual BACs that correspond to multi-locus DNA probes, in a manner that can efficiently be applied on a large scale. This approach also provides an alternative means of mapping DNA loci that exploits many advantages of 'radiation hybrid' mapping in taxa for which such hybrids are not available. The BAC-RF method is a practical and reliable approach for using high-density RFLP maps to anchor sequence-ready BAC contigs in highly-duplicated genomes, provides an alternative to high-density robotic gridding for screening BAC libraries when the necessary equipment is not available, and permits the expedient isolation of individual members of multigene or repetitive DNA families for a wide range of genetic and evolutionary investigations.

Protein kinase C-beta mediates lipoprotein-induced generation of PAI-1 from vascular endothelial cells

Elevated levels of low-density lipoproteins (LDL) and lipoprotein(a) [Lp(a)] have been considered strong risk factors for atherosclerotic cardiovascular disease. Increased production of plasminogen activator inhibitor-1 (PAI-1) has been implicated in the development of thrombosis and atherosclerosis. Previous studies by our group and others demonstrated that oxidation enhances LDL- and Lp(a)-induced production of PAI-1 in human umbilical vein endothelial cells (HUVEC). The present study examined the involvement of protein kinase C (PKC) and its isoform in vascular endothelial cells (EC) induced by native or oxidized LDL and Lp(a). Treatment with Lp(a) or LDL transiently increased PKC activity at 15 min and 5.5 h after the start of lipoprotein treatment in EC. Copper-oxidized LDL and Lp(a) induced greater PKC activation in EC compared with comparable forms of those lipoproteins. Additions of 1 microM calphostin C, a PKC-specific inhibitor, at the beginning or > or =5 h, but not > or = 9 h, after the initiation of lipoprotein treatment, blocked native and oxidized LDL- or Lp(a)-induced increases in PKC activity and PAI-1 production. Treatment of LDL, Lp(a), or their oxidized forms was induced in translocation of PKC-beta1 from cytosol to membrane in HUVEC. Treatments with 60 nM 379196, a PKC-beta-specific inhibitor, effectively prevented PAI-1 production induced by LDL, Lp(a), or their oxidized forms in HUVEC and human coronary artery EC. The results suggest that activation of PKC-beta may mediate the production of PAI-1 in cultured arterial and venous EC induced by LDL, Lp(a), or their oxidized forms.

The p44S10 locus, encoding a subunit of the proteasome regulatory particle, is amplified during progression of cutaneous malignant melanoma

Gene amplification is frequently present in human tumors, although specific target genes relevant to many amplified loci remain unidentified. An expression cloning assay enabled identification of a candidate oncogene derived from human chromosome 3p14.1. The cDNA retrieved from morphologically transformed cells contained the full-length protein coding region and detected an abundant transcript in the same cells. Sequence analysis revealed identity with the wild-type sequence of p44S10, a highly conserved subunit of the 26S proteasome that exhibits similarity to the Arabidopsis fus6/cop11 family of signaling molecules. p44S10 gene copy number and mRNA expression were increased in association with segmental 1.8 - 11-fold chromosomal gains in cutaneous malignant melanoma cell lines (5/13; 40%) and tumors (2/40; 5%), and in breast cancer MCF-7 cells. Likewise, malignant progression of human radial growth phase WM35 melanoma cells was associated with amplification and increased expression of endogenous p44S10, and increased expression of p44S10 was sufficient to induce proliferation of WM35 cells in vivo. The results demonstrate segmental copy number gains within chromosome 3p in cutaneous malignant melanoma and suggest that deregulation of a proteasome regulatory particle subunit may contribute to the malignant phenotype.

Caco-2 cell permeability vs human gastro-intestinal absorption: QSPR analysis

The aim of this study is to elucidate quantitative structure-permeability relationship (QSPR) of various organic molecules through Caco-2 cells, and to ascertain the relationship between gastrointestinal (GI) absorption in humans and Caco-2 cell permeability. Caco-2 cell permeability and human GI absorption data were obtained from the literature. The maximum hydrogen bond-forming capacity corrected for intra-molecular H-bonding (Hbc) and Lien's QSAR model were used in this study. The latest CQSAR software was utilized in calculating the logarithm of partition coefficient in octanol/water (Clog P) and in deriving all regression equations. For 51 compounds, a significant correlation was obtained between Caco-2 cell permeability (log Pcaco-2) and Hbc, octanol/PBS (phosphate buffered saline, pH 7.4) distribution coefficient (log Doct), log MW and an indicator variable (I) for the charge, with a correlation coefficient of 0.797. When these compounds were divided into three subgroups, namely neutral, cationic and anionic compounds, much better correlations (r = 0.968, 0.915 and 0.931, respectively) were obtained using different combinations of various physico-chemical parameters. A plot of human GI absorption vs. Caco-2 cell permeability obtained from different laboratories reveals that Caco-2 cell permeability cannot be used to precisely predict human GI absorption for compounds with Pcaco-2 below 5 x 10(-6) cm/s, due to interlaboratory and experimental variabilities, and the lack of a simple correlation between human GI absorption and Caco-2 cell permeability. Caco-2 cell permeability may be estimated from the structures of drug molecules using the above-mentioned physicochemical parameters. In general, for compounds with Pcaco-2 above 5 x 10(-6) cm/s, human GI absorption ranges from 50 to 100%. This is generally acceptable for development into oral dosage form. For the compounds with Pcaco-2 below 5 x 10(-6) cm/s, careful interpretation of caco-2 cell permeability and use of internal standard for comparison are recommended. Otherwise, good drug candidates may be excluded due to incorrectly predicted poor absorption.

Covalent attachment of DNA to glass supports using a new silane coupling agent and chemiluminescent detection

A new kind of silane coupling agent, N-(beta-aminoethyl)-gamma-aminopropyl triethoxysilane, was used for DNA direct attachment on the surfaces of glass supports, then the immobilized DNA was hybridized with horseradish peroxidase (HRP)-labeled probe, and detected by using enhanced chemiluminescent method. In comparison with gamma-aminopropyl triethoxysilane, the detection limits (S/N) of DNA were 10 pg and 75 pg respectively. Several experimental conditions of DNA attach-ING to glass supports were investigated, and the system of hybridization of nucleic acid on the surfaces of glass supports was developed.

Inhibition of herpes simplex virus type 1 and adenovirus type 5 by heterocyclic Schiff bases of aminohydroxyguanidine tosylate

Eleven heterocyclic Schiff bases of aminohydroxyguanidine tosylate (SB-AHGs), compounds I-XI, were tested for antiviral activity against herpes simplex virus type 1 (HSV-1) and adenovirus type 5 (Ad 5) via plaque reduction and virus yield reduction assays. This work was undertaken to test the hypothesis that low molecular weight SB-AHGs (MW < 235 for the free SB) make better antiviral agents than high MW SB-AHGs (MW > 300). The plaque reduction assay method demonstrated that three compounds, I, VII and IX, had moderate activity against HSV-1, with 50% inhibitory concentration (IC50) values of 38.0, 23.5 and 52.1 microM, respectively. Against Ad 5, compounds I, VIII and XI exhibited moderate activity, with IC50 values of 52.7, 19.3 and 5.1 microM, respectively. Among the compounds screened, compound I (1-[(3'-hydroxy-6'-methyl-2'-pyridyl)methylene]amino-3-hydroxyguanidi ne tosylate) was the most promising antiviral candidate, with selectivity indices (SI) of 10.2 (HSV-1) and 7.6 (Ad 5), respectively. Virus yield reduction assays indicated that compound I had less antiviral potency against HSV-1 than against Ad 5. The antiviral effects of compound I at a high input virus multiplicity of infection (MOI > 5) indicated that compound I had effective anti-adenoviral activity at 24 h post infection. This work demonstrated that some of SB-AHGs only have moderate antiviral activities against Ad 5 and HSV-1 viruses. In general, low MW SB-AHGs have low cytotoxicities to the host cells.

Disruption of the telomerase catalytic subunit gene from Arabidopsis inactivates telomerase and leads to a slow loss of telomeric DNA

Telomerase is an essential enzyme that maintains telomeres on eukaryotic chromosomes. In mammals, telomerase is required for the lifelong proliferative capacity of normal regenerative and reproductive tissues and for sustained growth in a dedifferentiated state. Although the importance of telomeres was first elucidated in plants 60 years ago, little is known about the role of telomeres and telomerase in plant growth and development. Here we report the cloning and characterization of the Arabidopsis telomerase reverse transcriptase (TERT) gene, AtTERT. AtTERT is predicted to encode a highly basic protein of 131 kDa that harbors the reverse transcriptase and telomerase-specific motifs common to all known TERT proteins. AtTERT mRNA is 10-20 times more abundant in callus, which has high levels of telomerase activity, versus leaves, which contain no detectable telomerase. Plants homozygous for a transfer DNA insertion into the AtTERT gene lack telomerase activity, confirming the identity and function of this gene. Because telomeres in wild-type Arabidopsis are short, the discovery that telomerase-null plants are viable for at least two generations was unexpected. In the absence of telomerase, telomeres decline by approximately 500 bp per generation, a rate 10 times slower than seen in telomerase-deficient mice. This gradual loss of telomeric DNA may reflect a reduced rate of nucleotide depletion per round of DNA replication, or the requirement for fewer cell divisions per organismal generation. Nevertheless, progressive telomere shortening in the mutants, however slow, ultimately should be lethal.

Analysis of cyclophosphamide and five metabolites from human plasma using liquid chromatography-mass spectrometry and gas chromatography-nitrogen-phosphorus detection

An assay method for the quantification of cyclophosphamide (CY) and five metabolites from human plasma is presented. The procedure is adapted to the chemical properties of the compounds of interest: non-polar compounds are extracted into methylene chloride, concentrated and analyzed by GC-NPD after derivatization, and the remaining aqueous fraction is deproteinated with acetonitrile-methanol prior to separation via reversed-phase HPLC and detection using atmospheric pressure ionization (API)-MS. Standard curves are linear over the required range and reproducible over five months. Plasma concentration-time profiles of CY and metabolites from a patient receiving CY by intravenous infusion (60 mg/kg, once a day for two days) are presented.

[Chemical composition of essential oil from leaves of litsea cubeba and its antifungal activities]

The 24 chemical constituents of the essential oil extracted from the leaves of Litsea cubeba have been identified by means of GC-MS technique. Among which, alpha-cis-ocimene(25.11%), 3,7-dimethyl-1,6-octadien-3-ol(16.85%) and n-transnerolidol (13.89%) were the principal components. In vitro this oil had a manifest antifungal activities with MIC between 0.03-0.4 microliter/ml for utilized pathogenic fungi and 1.0-2.0 microliters/ml for moulds.

[Chemical constituents of the essential oil from the fruits of Lindera glauca and its antifungal activities]

The chemical constituents of the two essential oils extracted from the fruits of Lindera glauca by hydrodistillation and petroleum ether have been studied by means of GC-MS. Among which, 32 kinds of constituents were identified in distilling oil and 22 kinds in solvent oil. The main components in distilling oil were n-carpric acid (25.39%), germacrene A (10.71%), n-dodecanole acid (10.08%), epishyobunol acetate (7.29%) and caryophyllene oxide (5.44%), and in solvent oil were camphene (17.55%), 3,6,6-trimethyl-2-norpinene (16.85%), capric acid, ethyl ester (13.61%), eucalyptol (8.10%), and alpha-cis-ocimene (7.38%), In vitro the distilling oil exhibited more manifest antifungal properties than the solvent oil with MIC between 0.03-0.5 ml/L for pathogenic fungi species and 1.0-1.5 ml/L for moulds. Almost having not contained the sesquiterpenoids and their derivatives in the solvent oil maybe were a reason of poor inhibitory.

Oncogene expression cloning by retroviral transduction of adenovirus E1A-immortalized rat kidney RK3E cells: transformation of a host with epithelial features by c-MYC and the zinc finger protein GKLF

The function of several known oncogenes is restricted to specific host cells in vitro, suggesting that new genes may be identified by using alternate hosts. RK3E cells exhibit characteristics of epithelia and are susceptible to transformation by the G protein RAS and the zinc finger protein GLI. Expression cloning identified the major transforming activities in squamous cell carcinoma cell lines as c-MYC and the zinc finger protein gut-enriched Kruppel-like factor (GKLF)/epithelial zinc finger. In oral squamous epithelium, GKLF expression was detected in the upper, differentiating cell layers. In dysplastic epithelium, expression was prominently increased and was detected diffusely throughout the entire epithelium, indicating that GKLF is misexpressed in the basal compartment early during tumor progression. The results demonstrate transformation of epithelioid cells to be a sensitive and specific assay for oncogenes activated during tumorigenesis in vivo, and identify GKLF as an oncogene that may function as a regulator of proliferation or differentiation in epithelia.

[The effect of granule-rhinitis on allergic nasal mucosa]

OBJECTIVE

To investigate the effect of granule-rhinitis on allergic rhinitis.

METHOD

Experimental guinea pigs with allergic rhinitis were treated with granule-rhinitis. During the total course of treatment, sneezing and nasal itching were observed and recorded and then compared quantitatively with those of the control groups. Histological changes of the nasal mucosa were observed.

RESULT

The various symptoms of allergic rhinitis were obviously relieved in the treatment group. Granule-rhinitis reduced inflammatory cell infiltration, particularly decreased the number of mast cells and eosinophils in the superficial layers of the nasal mucosa, and reduced the release of mediators from mast cells. It diminished the vasodilatation in nasal mucosa.

CONCLUSION

Granule-rhinitis is effective in the treatment of allergic rhinitis.

Down-regulation of the expression of O-acetyl-GD3 by the O-acetylesterase cDNA in hamster melanoma cells: effects on cellular proliferation, differentiation, and melanogenesis

The composition of the gangliosides of hamster melanoma cells is closely related to their cellular growth and degree of differentiation, with slow-growing, highly differentiated melanotic melanoma MI cells expressing GM3 and fast-growing, undifferentiated amelanotic Ab melanoma cells having a preponderance of GD3 and O-acetyl-GD3. To study the putative function of O-acetyl-GD3, we established stably transfected AbC-1 amelanotic hamster melanoma cells with O-acetylesterase gene from influenza C virus to hydrolyze the O-acetyl group from O-acetyl-GD3. The content of O-acetyl-GD3 in the transfected cells expressing O-acetylesterase gene was reduced by >90%. These O-acetyl-GD3-depleted cells differed from the parental ones in their cellular morphology, growth behavior, and melanogenesis activity. The absence of O-acetyl-GD3 in the transfected cells was accompanied by increased thick dendrite formation with an enlarged cell body, which is in striking contrast to the control cells, which were rounded and flattened, with few processes. Their growth was significantly slower than that of the control cells. They also demonstrated significantly lower tyrosinase activity and melanogenic potential. We suggest that the enhanced expression of melanoma-associated O-acetyl-GD3 ganglioside may stimulate cellular growth and suppress certain differentiated phenotypes such as dendrite formation but not melanogenesis.

[GC-MS analysis and inhibitory activity of the essential oil extracted from the leaves of Lindera communis]

The essential oil isolated from the dried leaves of Lindera communis was analyzed by means of gas chromatography-mass(GC-MS) technique, the structures of 23 chemical components were identified from it in total, among these, (-)-spathulenol(relative content 22.50%), endo-1,3,3-trimethyl-2-norbornanol, acetate (10.06%), caryophyllene oxide (6.74%) and germacrene B(6.71%) were the main constituents. And also the oil in vitro exhibited manifest antifungal and antibacterial activities against 4 fungi pathogen species and 4 bacterial species with MIC between 0.08-0.8 ml/l.

Antiviral tannins from two Phyllanthus species

Seven ellagitannins isolated from Phyllanthus myrtifolius and P. urinaria (Euphorbiaceae) have been shown, for the first time, to be active against Epstein-Barr virus DNA polymerase (EBV-DP) at the microM level. All these compounds have the same moiety of a corilagin, and differ from each other by different substitutions at C-2 and C-4 of the glucose core. SAR analysis and molecular modeling reveal that the essential pharmacophore of these tannins resides in the corilagin moiety. The outer complex carboxylic acid moieties appear to act only as auxopharmacore.

Quantitative structure-activity relationship analysis of phenolic antioxidants

In this report, the quantitative structure-activity relationship (QSAR) analyses of substituted phenols, vitamin E derivatives and flavonoids are presented. Two models have been derived using calculated parameters such as the heat of formation (Hf), the energy of the lowest unoccupied molecular orbital of radicals (E(lumo-r)) the energy of the highest occupied molecular orbital of the parent compounds (E(homo)) and the number of hydroxyl groups (OH). These models can be used to estimate the redox potentials or antioxidant activities of new substituted phenolic compounds or vitamin E derivatives. The Trolox equivalent antioxidant capacities (TEACs) of 42 different flavonoids are found to be mainly governed by the number and location of hydroxyl groups on the flavonoid ring system.

Strategy for cross-protection among Shigella flexneri serotypes

Based upon the lipopolysaccharide (LPS) structure and antigenicity of Shigella group B, a strategy for broad cross-protection against 14 Shigella flexneri serotypes was designed. This strategy involves the use of two S. flexneri serotypes (2a and 3a), which together bear the all of the major antigenic group factors of this group. The novel attenuated strains used in these studies were S. flexneri 2a strain CVD 1207 (DeltaguaB-A DeltavirG Deltaset1 Deltasen) and S. flexneri 3a strain CVD 1211 (DeltaguaB-A DeltavirG Deltasen). Guinea pigs were immunized with an equal mixture of these strains and later challenged (Sereny test) with a wild-type S. flexneri serotype 1a, 1b, 2b, 4b, 5b, Y, or 6 strain of demonstrated virulence in the same model. Guinea pigs that were immunized with these two vaccine strains produced serum and mucosal antibodies that cross-reacted with all the S. flexneri serotypes tested (except of S. flexneri serotype 6) as assessed by enzyme-linked immunosorbent assay, immunoblotting, and slide agglutination. Furthermore, the combination vaccine conferred significant protection against challenge with S. flexneri serotypes 1b, 2b, 5b, and Y but not with serotypes 1a, 4b, or (as predicted) 6.

Inhibition of human aldehyde dehydrogenase 1 by the 4-hydroxycyclophosphamide degradation product acrolein

In a previous study, we observed that the elimination clearance of 4-hydroxycyclophosphamide (HCY) in patients receiving cyclophosphamide (CY) 60 mg/kg/day by 1-h i.v. infusion for 2 consecutive days decreased from day 1 to day 2 due to an apparent decrease in human aldehyde dehydrogenase 1 (ALDH1) activity. Here, the mechanism for the decrease in ALDH1 activity after CY administration was investigated. In human liver cytosol incubations, HCY inhibited ALDH activity mainly through its degradation product acrolein, whereas carboxyethylphosphoramide mustard inhibited ALDH activity only at supraclinical concentrations. Other CY metabolites evaluated, phosphoramide mustard and chloroacetaldehyde, did not inhibit ALDH. The inhibition of ALDH1 activity by acrolein in incubations with human erythrocyte ALDH1 was competitive with a Ki of 0.646 microM. The inhibition was independent of preincubation time and reversible by dialysis. The percentage of inhibition of ALDH1 activity in vivo by acrolein in patients receiving CY was calculated based on the in vitro Ki of acrolein, the in vitro Km of HCY, and the in vivo peak blood concentrations of HCY and acrolein. The calculations indicated that the activity of ALDH1 was inhibited by 85, 88, and 91% on days 1, 2, and 3 (24 h after the dose on day 2) of CY administration, respectively. The increase in ALDH1 inhibition with time is consistent with the decrease in HCY elimination clearance and the increase in HCY area under the plasma concentration time curve with time.

A new system for rapid measurement of ATP

The paper introduces a new type instrument for rapid measuring ATP. The system consists of a micromodule ATP sensor and an instrument for measuring weak light transmitted by optic fiber. The micromodule ATP sensor mainly is composed of enzyme membrane, a probe and a bundle of optic fiber. The instrument measuring weak light consists of photomultiplier, high voltage power, pulse amplifier and counter. The instrument was characterized by simple structure, small size, rapid response time (< 5s), high sensitivity (10(-12) mol/L), stable performance (measuring the same sample for 50 times, CV < 5%), long enzyme storage time (> 3 months).

QSAR analysis of polyamine transport inhibitors in L1210 cells

PURPOSE

In this paper, the authors attempt to construct a mathematical model to correlate the biological activities of 63 polyamine transport inhibitors in L1210 cells with their physicochemical parameters.

METHOD

The inhibitory constants (Ki) were obtained from the published work of Bergeron et al. Non-weighted least square method was used in deriving the regression equations with a BMDP program. An AM1 subroutine of the HyperChem program was used to optimize the geometry and calculate the molecular dipole moments and the distance between two terminal amino groups. A CQSAR program was used to calculate Clog P (oct./w.).

RESULTS

A good correlation (r2 = 0.81) was obtained by using a five-parameter equation including the distance between two terminal amino groups (d), the number of cationic charge (Charge), molecular weight (MW), dipole moment (mu), and hydrogen bond forming ability (Hb).

CONCLUSION

This model accounts for 81% of the variance in the data and can be used to estimate transport-inhibitory activity of many other polyamine analogues. It gives some quantitative information about the relationship between the polyamine analogues' function as transport inhibitors and their molecular structures.

Pharmacokinetics of cyclophosphamide and its metabolites in bone marrow transplantation patients

OBJECTIVES

To characterize the pharmacokinetics of cyclophosphamide and 5 of its metabolites in bone marrow transplant patients and to identify the mechanism of the increase in 4-hydroxycyclophosphamide area under the plasma concentration-time curve (AUC) from day 1 to day 2 of cyclophosphamide administration.

METHODS

Cyclophosphamide was administered by intravenous infusion (60 mg/kg over 1 hour, once a day) for 2 consecutive days to 18 patients. Cyclophosphamide and 4-hydroxycyclophosphamide concentration time data on day 1 and day 2 were fitted to a model to estimate 4-hydroxycyclophosphamide formation (CLf) and elimination (CLm) clearances. Erythrocyte aldehyde dehydrogenase-1 activity was measured ex vivo just before the first cyclophosphamide infusion was started (0 hours) and 24 hours after the second cyclophosphamide infusion (48 hours).

RESULTS

From day 1 to day 2, the AUC of cyclophosphamide, deschloroethyl cyclophosphamide and phosphoramide mustard decreased 24.8%, 51%, and 29.4% (P < .02), the AUC of 4-hydroxycyclophosphamide and carboxyethylphosphoramide mustard increased 54.7% and 25% (P < .01), whereas the AUC of phosphoramide mustard was not significantly changed (P > .3). The CLf of 4-hydroxycyclophosphamide increased 60% (P < .001), its CLm decreased 27.7% (P < .001), and the fraction of cyclophosphamide dose converted to 4-hydroxycyclophosphamide increased 16% (P < .001) from day 1 to day 2. The activity of patient erythrocyte aldehyde dehydrogenase-1 decreased 23.3% (P < .02) from 0 hours to 48 hours.

CONCLUSIONS

The AUC of 4-hydroxycyclophosphamide increased from day 1 to day 2 as a result of increased formation and decreased elimination clearances of 4-hydroxycyclophosphamide. Aldehyde dehydrogenase-1 activity appears to decline as a consequence of cyclophosphamide administration.

Manganese inhibits mitochondrial aconitase: a mechanism of manganese neurotoxicity

The symptoms of Mn-induced neurotoxicity resemble those of Parkinson's diseases. Since iron (Fe) appears to play a pivotal role in pathophysiology of Parkinson's disease, we set out to test the hypothesis that alterations in Fe-requiring enzymes such as aconitase contribute to Mn-induced neurotoxicity. Mitochondrial fractions prepared from rat brain were preincubated with MnCl2 in vitro, followed by the enzyme assay. Mn treatment significantly inhibited mitochondrial aconitase activity (24% inhibition at 625 microM to 81% at 2.5 mM, p<0.05). The inhibitory effect was reversible and Mn-concentration dependent, and was reversed by the addition of Fe (0.05-1 mM) to the reaction mixture. In an in vivo chronic Mn exposure model, rats received intraperitoneal injection of 6 mg/kg Mn as MnCl2 once daily for 30 consecutive days. Mn exposure led to a region-specific alteration in total aconitase (i.e. , mitochondrial+cytoplasmic): 48.5% reduction of the enzyme activity in frontal cortex (p<0.01), 33.7% in striatum (p<0.0963), and 20.6% in substantia nigra (p<0.139). Chronic Mn exposure increased Mn concentrations in serum, CSF, and brain tissues. The elevation of Mn in all selected brain regions (range between 3.1 and 3.9 fold) was similar in magnitude to that in CSF (3.1 fold) rather than serum (6. 1 fold). The present results suggest that Mn alters brain aconitase activity, which may lead to the disruption of mitochondrial energy production and cellular Fe metabolism in the brain.

Influence of glycation on LDL-induced generation of fibrinolytic regulators in vascular endothelial cells

Hyperglycemia and dyslipidemia are two biochemical markers of diabetes mellitus. Increased incidence of cardiovascular disease and impaired fibrinolytic activity have been found in diabetic subjects. Previous studies have demonstrated that low density lipoproteins (LDLs) stimulate the production of plasminogen activator inhibitor-1 (PAI-1) and reduce the generation of tissue plasminogen activator (tPA) in vascular endothelial cells (ECs). The present study investigated the effect of glycated LDL on the production of PAI-1 and tPA in cultured human umbilical vein ECs (HUVECs). Glycation increased the abundance of glucitollysine and conjugated dienes in LDL and amplified the overproduction of PAI-1 and the reduction in tPA generation from HUVECs induced by LDL. The steady-state levels of PAI-1 mRNA in glycated LDL-treated ECs were significantly higher than those in native LDL-treated cells. Actinomycin D blocked the increase in PAI-1 generation induced by glycated LDL. Glycated LDL did not significantly reduce the levels of tPA mRNA but attenuated de novo synthesis of tPA in ECs. Treatment with 25 mmol/L aminoguanidine, an antioxidant and inhibitor of the formation of advanced glycation end products, during glycation normalized glycated LDL-induced generation of PAI-1 and tPA in ECs. The results of the present study indicate that glycation enhances the production of PAI-1 and attenuates tPA synthesis in ECs induced by LDL, which may contribute to the increased incidence of cardiovascular complications in diabetes. Formation of advanced glycation end products or peroxidation may be involved in glycated LDL-induced alterations in the generation of fibrinolytic regulators from ECs.

Regulation of human mast cell beta-tryptase: conversion of inactive monomer to active tetramer at acid pH

At neutral pH, human mast cell beta-tryptase is stabilized in its enzymatically active, tetrameric form by heparin, and resists inhibition by biologic protease inhibitors. After dissociation of beta-tryptase from heparin, active tetramers rapidly convert to inactive monomers in an isotonic, neutral pH environment. Although reversible transition states probably exist during this conversion, once inactive monomers form, addition of heparin fails to reconstitute active tetramer at neutral pH. The current study shows that complete reactivation of inactive monomers can occur at acidic pH in a heparin-independent manner. The respective rate-determining steps for formation of tetramer and active enzyme from inactive monomers exhibit second and first order kinetics based on an analysis of initial reaction rates. The optimal pH for tetramer formation and reactivation is about 6, suggesting His residues play a critical role. The optimal ionic strength equivalent is 160 mM NaCl; and the optimal temperature range is 22 degrees C to 37 degrees C. We propose a sequential three-step reactivation process at acidic pH, dimerization of monomers (rate-determining second order step), rapid formation of inactive tetramers, and slow formation of active tetramers (overall rate-determining first order step). Whether reactivation of human beta-tryptase occurs at extracellular or intracellular sites, where the pH is acidic in vivo, should be considered.

Determination of lamotrigine in biologic materials by a simple and rapid liquid chromatographic method

Lamotrigine (LTG), a newly introduced antiepileptic drug, appears to have potential therapeutic advantages for the treatment of patients with partial-onset seizures. Increasing clinical application and research of LTG demand a simpler and more rapid analytical procedure to determine LTG concentration in body fluids and tissues. The authors have developed an effective one-step procedure for sample preparation followed by high-performance liquid chromatography (HPLC) to quantitate LTG in plasma, urine, and brain tissues. Body fluids and brain homogenates were treated with cold acetonitrile to precipitate protein. The samples were fractionated on a 250 x 4.6 mm C18 reversed-phase column with an isocratic mobile system consisting of potassium phosphate buffer, acetonitrile, and methanol (70:16:14). The method had a LTG detection limit of 0.02 microg/ml in plasma and 0.03 microg/ml in urine. The coefficients of variation were <2.7% for intraday and 4.2% for interday analyses. The recovery of LTG added to plasma, urine, and brain homogenate ranged from 98% to 100%. The method was applied to a clinical study to determine plasma and urine concentrations of LTG in subjects receiving a single oral dose of LTG. The calculated pharmacokinetic parameters were comparable to those previously reported. The method proved to be simple, fast, reproducible, and useful in clinical investigation and monitoring of LTG concentrations.

Clinical observation on vertical transmission of human papillomavirus

OBJECTIVE

To observe the possibility of maternal-fetal vertical transmission of human papillomavirus (HPV) via amniotic fluid.

SUBJECTS AND METHODS

Specimens of cervical secretions from 30 pregnant women were obtained during the third trimester before rupture of membrane, and specimens of pharyngeal secretions of their neonates were obtained 12-48 h after birth. Amniotic fluids were collected in 13 pregnant women during cesarean section. The presence of HPV types 6, 11, 16, 18, 31, 33, 35, 38 deoxyribonucleic acid were detected by consensus polymerase chain reaction.

RESULTS

HPV deoxyribonucleic acid was found in 16 cervical secretions, 14 pharyngeal secretions and in 3 amniotic fluids, the positive rate was 53.3%, 46.7%, 23.1% respectively. The pharyngeal secretion was also HPV positive in one of the three neonates from the amniotic fluid positive mothers.

CONCLUSION

The results indicate that HPV can be transmitted in utero through amniotic fluid and cesarean section can not protect the neonates against vertical transmission completely.

Dihydroorotate dehydrogenase inhibitors: quantitative structure-activity relationship analysis

PURPOSE

The main purpose of this study is to analyze the quantitative structure-activity relationship of two series of dihydroorotate dehydrogenase inhibitors (leflunomide and quinoline carboxylic acid analogues), and to determine the structural requirements for optimum activity of these analogues.

METHODS

A new CQSAR program was used in deriving regression equations and calculating the octanol/water partition coefficient and the molar refractivity values. The molecular modeling was performed using the HyperChem program.

RESULTS

Statistically significant correlations were obtained using a combination of 3-4 parameters. The structural requirements for optimum activity and critical regions for the inhibitory activity of dihydroorotate dehydrogenase were identified.

CONCLUSIONS

The quantitative structure-activity relationship analysis demonstrated that two series of dihydroorotate dehydrogenase inhibitors may bind to different binding sites on the enzyme. These results provide a better understanding of dihydroorotate dehydrogenase inhibitor-enzyme interactions, and may be useful for further modification and improvement of inhibitors of this important enzyme.

Development of HIV protease inhibitors: a survey

In the treatment of infections caused by rapidly mutating viruses like human immunodeficiency virus (HIV), combination therapy with multiple drugs acting by different mechanisms offers several advantages over monotherapy. It may provide: synergistic effect, possible reduction of dosages and side-effects, and reduction of the chance of drug resistance. In the past few years, hundreds of HIV protease inhibitors have been synthesized and tested in order to overcome the limitations of reverse transcriptase inhibitors like zidovudine and others. In this review, emphasis is placed on the development of HIV protease inhibitors as antiviral agents against HIV, and structure-activity relationship analysis of saquinavir and related compounds. Limitations of some protease inhibitors and ways to overcome the shortcomings are presented. Among these many protease inhibitors four have been marketed during 1995-1997. They are saquinavir, ritonavir, indinavir and nelfinavir. Their different structural features, important physicochemical, pharmacokinetic and clinical profiles are presented in a table form for easy comparison. It is hoped that in the future new drugs based on additional mechanisms can be developed for the treatment of AIDS.

Human tryptase fibrinogenolysis is optimal at acidic pH and generates anticoagulant fragments in the presence of the anti-tryptase monoclonal antibody B12

Human tryptase is uniquely regulated by its association with heparin and resists inhibition by biological protease inhibitors. The effects of pH and B12, an IgG anti-tryptase mAb, on cleavage of the synthetic substrate tosyl-Gly-Pro-Lys-p-nitroanilide and of the biological substrate fibrinogen by tryptase were examined. Tosyl-Gly-Pro-Lys-pnitroanilide cleavage was optimal at neutral pH and was inhibited by the B12 mAb at acidic and neutral pH values. At pH 7.5, inhibition was reversible and noncompetitive. In contrast, the optimal pH for tryptase to cleave fibrinogen was acidic. B12 dramatically enhanced the rate and extent that tryptase cleaved all three fibrinogen subunits at pH 6.0 to 6.5, but inhibited these activities at neutral pH. Major fibrinogen cleavage fragments generated at acidic pH by the B12:tryptase complex were identical with those made by plasmin. Thus, at acid pH, tryptase alone destroyed the ability of fibrinogen to clot, while the B12:tryptase complex increased the rate of fibrinogenolysis and also generated the anticoagulant, fragment D. The acidic pH optimum for tryptase fibrinogenolysis may direct this activity to tissue sites of inflammation. A putative biological equivalent to B12 would limit tryptase fibrinogenolytic activity at sites of neutral pH, such as blood, but would augment activity at acidic sites.

[Simultaneous spectrophotometric determination of three-component mixture by two partial least squares methods]

Two partial least squares methods, classical partial least squares (PLS) and partial least squares based on a kernel algorithm (KPLS), were studied for simultaneous determination of a three-component mixture. Three programs called SPGRAFA, SPGRPLS and SPGRKPLS were designed to perform the calculations. Eight error functions were calculated for deducing the number of factors. Because the size of the kernal matrix was much smaller than the original data matrix, the KPLS applied to calculating the matrix with many wavelengths and fewer number of samples. Experimental results showed both methods to be successful even there was overlap of spectra and agreed well.