[Synergistic interaction between Ys-96, a bisbenzylisoquinoline compound derived from Stephania tetrandra, and adriamycin or vincristine against human cancer cell lines in vitro]

OBJECTIVE

To study in vitro the anticancer interaction between Ys-96, a bisbenzylisoquinoline compound derived from Stephania tetrandra, and adriamycin or vincristine against human cancer cell lines.

METHOD

Using human breast cancer cell MCF-7 and its adriamycin-resistant cell line MCF-7/Adr, and human nasopharyngeal cancer cell KB and its vincristine-resistant cell line KBv200 in an in vitro system, anticancer interaction between Ys-96 and adriamycin or vincristine was evaluated with a method reported by Berenbaum.

RESULT

The SFIC values (sum of fractional inhibitory concentration) of the combinations with 3 different ratios between Ys-96 and adriamycin or vincristine were markedly less than 1.0, and the shapes of all the isobologram curves were concave.

CONCLUSION

The synergistic interaction between Ys-96 and adriamycin or vincristine against the above human cancer cell lines was positively observed in vitro.

Ab initio studies of some amino acid residue complexes with 4-mercaptopyridine as a model for thymitaq (AG337), an inhibitor of thymidylate synthase

The complex formed by isopentane, as a model for the isoleucine residue present in the wild-type thymidylate synthase, with 4-mercaptopyridine as a fragment of the thymidylate synthase inhibitor Thymitaq (AG337) is investigated with ab initio quantum chemical calculations at Hartree-Fock and MP2 levels, using the 3-21G* basis set. The binding energy is compared with the binding energies of 4-mercaptopyridine with amino acid residues found in mutant thymidylate synthase enzymes. As compared with isoleucine, alanine and glycine do not show binding, in agreement with enzyme-inhibition results.

[Purification and partial characterization of antagonistic proteins from Bacillus subtilis B034]

Bacillus subtilis B034, an antagonistic bacteria isolated from the phyllosphere of rice, strongly inhibits the growth of Xanthomonas oryzae pv. oryzae which causes the rice bacterial blight. Crude extract was obtained by precipitation of the cell-free culture of B034 with 70% saturated (NH4)2SO4. The suspension of the precipitate strongly inhibits Xanthomonas oryzae pv. o-ryzae, and it is thermostable, resistant to trypsin, partial sensitive to proteinase K, pronase E and chloroform. Its active pH range is wide, from 4.0 to more than 12.0, relative more stable in high pH. Two antagonistic peaks were obtained from the crude extract of B034 after Phenyl-Sepharose CL-4B, DEAE-Sephacel and FPLC Superdex 75 HR 10/30 column chromatography. One of these two peaks, named P2, was showed only single band with 50.3 kD and pI6.25 in SDS-PAGE and PAGE-IEF, respectively. The N-terminal partial sequence of protein P2 was analyzed.

New AccI polymorphism in the follicle-stimulating hormone beta-subunit gene and its prevalence in three Southeast Asian populations

A thymine-cytosine substitution was identified in exon 3 (codon 76, TAT to TAC) of the human follicle-stimulating hormone (FSH) beta-subunit gene. The nucleotide change led to creation of an AccI digestion site. The frequencies of the A allele (with AccI site) in Chinese (n = 201), Malays (n = 168) and Indians (n = 132) were 0.358, 0.333 and 0.402, respectively. The new FSH beta-subunit marker may be useful in gene tracking and association studies.

The clinical and epidemiological significance of serum PreS1/anti-PreS1 in HBV infection

OBJECTIVE

To investigate whether PreS1 antigen and/or anti-PreS1 antibody in serum might have some significance different from routine hepatitis B virus (HBV) markers in hepatitis B virus infection.

METHODS

Forty-six acute hepatitis B patients and 377 chronic persistent hepatitis patients were examined to assess the clinical significance of serum PreS1/anti-PreS1. HBV family clustering analysis was carried out in a village in Shanghai suburb area, and case-control study on role of PreS1 in HBV spreading was undertaken in Tangshan, Hebei province.

RESULTS

PreS1 in HBsAg positive sera from chronic persistent hepatitis patients correlated with HBV DNA (P < 0.05), while the presence of PreS2 in HBsAg positive sera was much more common than that of PreS1 and had no correlation with HBeAg or HBV DNA. Among 46 patients with acute hepatitis B, the appearance of anti-PreS1 antibody in serum correlated with the disappearing or decreasing of both PreS1 and ALT. In antiviral treatment, PreS1 antigen turned negative much earlier than PreS2 and HBsAg in acute hepatitis B patients' sera. Family clustering analysis suggested that people with PreS1 positive in serum were more infective than those with HBsAg positive alone (P < 0.01). The case-control study showed that chronic hepatitis B patients with PreS1 positive in serum played a much more important role in HBV spreading than those with PreS1 negative (P < 0.01) and asymptomatic HBsAg carriers (P < 0.01), and the odds ratios (OR) were 3.8 and 3.2, respectively.

CONCLUSIONS

Serum PreS1 closely correlates with active virus replication, and PreS1/anti-PreS1 status indicates the outcome of acute hepatitis B. The serum PreS1/anti-PreS1 marker is of some significance in HBV epidemiology as well.

Coimmobilization of glucoamylase and glucose isomerase by molecular deposition technique for one-step conversion of dextrin to fructose

Glucose isomerase was immobilized by itself with adsorption and coimmobilized with glucoamylase by molecular deposition technique using macroporous trimethylamine polystyrene beads. Approximately 77.5% of the enzyme added was immobilized. The pH-activity curve of the immobilized glucose isomerase was broadened, resulting in 75% retention of its maximum activity at pH 6.2. The Km of the immobilized glucose isomerase was 1.28-fold that of the soluble one. When the two enzymes were immobilized together, the system was found capable of functioning at pH 6.0 to produce fructose from starch and dextrin. At this pH, the total fructose output of the coimmobilized enzyme system after 24 h was 1.9 times that of the free enzyme system.

Cloning and characterization of a novel mammalian PP2C isozyme

PP2C is a structurally diversified protein phosphatase family with a wide range of functions in cellular signal transduction. A novel PP2C subtype, designated PP2Cdelta, was identified from a rat cDNA clone, which encodes a protein of 392 amino acid residues. While PP2Cdelta shares approximately 30% sequence identity in its catalytic domain with the mammalian PP2C, it lacks a 90-residue carboxyl-terminal sequence conserved in mammalian PP2C. Northern blot analysis showed that PP2Cdelta is widely expressed in rat tissues. The transcription of the PP2Cdelta gene was activated in response to stress, such as the addition of ethanol to the culture medium or UV irradiation of cells. Recombinant PP2Cdelta purified from bacteria exhibited a potent Mn2+-dependent serine/threonine phosphatase activity. Unlike other members of the PP2C family, the activity of PP2Cdelta was inhibited, rather than stimulated, by Mg2+. Transfection with PP2Cdelta resulted in inhibition of cell growth, precluding generation of stable 293 or CHO transfectants. Using a modified tetracycline-regulated PP2Cdelta-GFP dicistronic expression cassette, it was revealed that overexpression of PP2Cdelta blocked cell cycle progression and arrested cells at early S phase, resulting in inhibition of DNA synthesis and leading to cell death. These results suggest that PP2Cdelta plays a role in regulation of cell cycle progression via dephosphorylation of its substrates whose appropriate phosphorylation states might be crucial for cell proliferation.

Probing the folate-binding site of human thymidylate synthase by site-directed mutagenesis. Generation of mutants that confer resistance to raltitrexed, Thymitaq, and BW1843U89

Human thymidylate synthase (TS) contains three highly conserved residues Ile-108, Leu-221, and Phe-225 that have been suggested to be important for cofactor and antifolate binding. To elucidate the role of these residues and generate drug-resistant human TS mutants, 14 variants with multiple substitutions of these three hydrophobic residues were created by site-directed mutagenesis and transfected into mouse TS-negative cells for complementation assays and cytotoxicity studies, and the mutant proteins expressed and characterized. The I108A mutant confers resistance to raltitrexed and Thymitaq with respective IC50 values 54- and 80-fold greater than wild-type but less resistance to BW1843U89 (6-fold). The F225W mutant displays resistance to BW1843U89 (17-fold increase in IC50 values), but no resistance to raltitrexed and Thymitaq. It also confers 8-fold resistance to fluorodeoxyuridine. Both the kinetic characterization of the altered enzymes and formation of antifolate-resistant colonies in mouse bone marrow cells that express mutant TS are in accord with the IC50 values for cytotoxicity noted above. The human TS mutants (I108A and F225W), by virtue of their desirable properties, including good catalytic function and resistance to antifolate TS inhibitors, confirm the importance of amino acid residues Ile-108 and Phe-225 in the binding of folate and its analogues. These novel mutants may be useful for gene transfer experiments to protect hematopoietic progenitor cells from the toxic effects of these drugs.

Discrete distribution of the neuropeptide Y Y5 receptor gene in the human brain: an in situ hybridization study

The present study investigated the regional distribution of putative 'food-intake'-related neuropeptide Y Y5 receptor gene using cRNA in situ hybridization in various regions of the normal control post-mortem human brain. Interestingly, significant levels of Y5 receptor expression were detected in the hypothalamus; the arcuate nucleus being particularly enriched compared to other hypothalamic nuclei. Surprisingly, strong hybridization signals were also noted in the stratum granulosum of the dentate gyrus contrasting with lower levels of Y5 receptor transcripts in other regions of the hippocampal formation. The cerebral cortex, basal ganglia and thalamus were not enriched with Y5 receptor mRNA. It thus appears that the expression of the Y5 receptor gene in the human brain is rather restricted with enrichment in areas consistent with the involvement of this receptor type in the modulation of appetite and seizures.

[The connotation investigation of "female-male" in Chinese traditional medicine nomenclature]

The connotation investigation of "female-male" in nomenclature of Polygonum multiflorum Thunb, suggests that the female-male" in Chinese medicine nomenclature is generalized concept. It has three connotation, including correlation, relativity identity. It's concrete use of materialist dialectics in Chinese medicine.

Conformational probes for elucidating the nature of substance P binding to the NK1 receptor: initial efforts to map the Phe7-Phe8 region

Three substance P analogs with conformation constraints in the Phe7-Phe8 region have been prepared in connection with an effort to differentiate two families of potential conformations for the binding of substance P to its NK1 receptor. While the analogs did not bind the NK1 receptor with high affinity, the synthesis of the analogs demonstrated the utility of a general method for constructing piperazinone based peptidomimetics.

[Reversal effect of Ys-96, a bisbenzylisoquinoline, on adriamycin or vincristine resistance in human cancer cells in vitro]

OBJECTIVE

Reversal effect of Ys-96, a bisbenzylisoquinoline, on the resistance of human cancer cells to adriamycin or vincristine was studied in vitro.

METHOD

In an in vitro culture system of human cancer cells MCF-7 and its adriamycin-resistant line MCF-7/Ad or KB and its vincristine-resistant line KBv200, the sensitivity(IC50) of the resistant cell lines to adriamycin or vincristine was evaluated with a MTT assay.

RESULT

IC50 value of adriamycin or vincristine in combination with Ys-96 at a concentration of 1.00 mumol/L against MCF-7/Ad or KBv200 was found to be close to that of adriamycin alone or vincristine alone against the sensitive cell line MCF-7 or KB.

CONCLUSION

The drug resistance of MCF-7/Ad or KBv200 could be essentially reversed by Ys-96 at a concentration of 1.00 mumol/L.

Dynorphin A as a potential endogenous ligand for four members of the opioid receptor gene family

Dynorphin A is an endogenous opioid peptide that activates the kappa opioid receptor (KOR) with high potency. Some studies also showed that the distribution and functional activity of dynorphin A are not completely correlated with those of KOR, suggesting that dynorphin A may interact with other receptors. To investigate the possibility that dynorphin A may serve as an agonist for other opioid receptors, we took the advantage of the cloning of the three major types of opioid receptors, mu (MOR), delta (DOR) and KOR, and examined their affinity for and their activation by dynorphin A. We used mammalian cells transfected with each of the cDNA clones for the human receptors hMOR, hDOR, hKOR and showed that dynorphin A displaced [3H]-diprenorphine binding with Ki values in the nanomolar range at all three receptors. We also showed that, when hMOR, hDOR or hKOR was coexpressed with a G protein-activated potassium channel in Xenopus oocytes, dynorphin A induced a potassium current with EC50 values in the nanomolar range for all three receptors. Furthermore, we showed that the human hORLI, an opioid receptor-like receptor that has been identified as a novel member of the opioid receptor gene family, displayed dynorphin A binding and functional activation. These results indicate that dynorphin A is capable of binding to and functional activation of all members of the opioid receptor family, suggesting that, as a potential endogenous agonist, its activity in humans may involve interaction with other members of the opioid receptor family in addition to kappa receptors.

[Molecular cloning and DNA sequencing of OspC gene of two strains Borrelia burgdorferi isolated in China]

OBJECTIVE

To investigate the variation of OspC gene in two Chinese isolates of Borrelia burgdorferi.

METHODS

PCR technique was used to amplify the OspC gene from the whole cellular DNA of isolates BT01 and BJ-9011. The amplified products were inserted into plasmid pGEM-3ZF(+) and sequenced.

RESULTS

Except the signal peptide, the OspC genes of the two isolates BT01 and BJ-9011 were 579 bp and 576 bp which encode 193, 192 amino acids respectively. The nucleotide and amino acids sequence identity between the two strains was 86% and 83%. High homology exists between these Chinese isolates and several foreign isolates (PBi, PKo, B31), especially in BJ-9011. It had 99% nucleotide and amino acid sequence identified with B31.

CONCLUSION

Variations in OspC genes are noted between the two Chinese Borrelia burgdorferi isolates and foreign isolates.

Isolation and characterization of thymitaq (AG337) and 5-fluoro-2-deoxyuridylate-resistant mutants of human thymidylate synthase from ethyl methanesulfonate-exposed human sarcoma HT1080 cells

Thymidylate synthase plays an essential role in the synthesis of DNA. Recently, several new and specific thymidylate synthase inhibitors that occupy the folate binding site, including Tomudex(R), BW1843U89, and Thymitaq, have demonstrated therapeutic activity in patients with advanced cancer. In order to find drug-resistant forms of human thymidylate synthase for gene therapy applications, human sarcoma HT1080 cells were exposed to ethyl methanesulfonate and Thymitaq selection. Thymitaq-resistant clonal derived sublines were established, and analysis indicated that both gene amplification and point mutations contributed to drug resistance. Eight mutant cDNAs that were identified from Thymitaq-resistant sublines were generated by site-directed mutagenesis and transfected into thymidylate synthase-negative cells. Only K47E, D49G, or G52S mutants retain enzyme activity. Moreover, cytotoxicity studies demonstrated that D49G and G52S transfected cells, besides displaying resistance to Thymitaq with IC50 values 40- and 12-fold greater than wild-type enzyme transfected cells, respectively, also lead to fluorodeoxyuridine resistance (26- and 97-fold in IC50 values, respectively) but not to Tomudex or BW1843U89. Characterization of the purified altered enzymes obtained from expression in Escherichia coli is consistent with the cell growth inhibition results. We postulate that the D49G or G52S mutation leads to the structural perturbation of the highly conserved Arg50 loop, decreasing the binding of thymidylate synthase to the inhibitors, Thymitaq and fluorodeoxyuridylate.

Regulation of expression of neuropeptide Y Y1 and Y2 receptors in the arcuate nucleus of fasted rats

Neuropeptide Y is expressed in neurons of the hypothalamic arcuate nucleus and has been ascribed a role as a stimulant of food intake. Neuropeptide Y Y1 and Y2 receptors are also localised in the arcuate nucleus, and it has been suggested that the Y1 receptor mediates part of the effect of neuropeptide Y on feeding behaviour. In the present study, immunohistochemistry and in situ hybridization were used to investigate the effect of food deprivation on the expression of Y1 and Y2 receptors in the arcuate nucleus of the rat. Fasting for 48 h induced a decrease in the number and area of Y1 receptor immunoreactive neurons in the arcuate nucleus. Furthermore, arcuate Y1 receptor mRNA levels also decreased after food deprivation. The decrease in the number of the Y1 receptor immunoreactive neurons was partially attenuated by supplementing the drinking water with 10% glucose. In contrast, fasting did not significantly change Y2 receptor mRNA levels in the arcuate nucleus. These results support the view that Y1 receptors in the arcuate nucleus play a role in the feeding pattern induced by neuropeptide Y.

Should peri-operative infra-inguinal graft duplex scans be routinely performed?

BACKGROUND

The ability of duplex ultrasound graft surveillance to detect graft stenosis is well documented. However, the optimal time to commence duplex ultrasound graft surveillance is not clear.

METHODS

An early duplex ultrasound study was performed on 90 infra-inguinal bypass grafts within 2 weeks of surgery. Further duplex scans were performed at intervals after surgery of 1 month, 3 months, 6 months, 1 year and then annually. An ankle/brachial systolic pressure index (ABI) was performed before the infra-inguinal bypass and then 24 h after the surgery. The ABI was also routinely measured at the time of each graft duplex examination.

RESULTS

Six graft thromboses (6.7%) were demonstrated on the first graft duplex within 2 weeks of the surgery. The 24-hour postoperative resting ABI were less than 0.5 in all six cases. Significant graft stenoses (> 50%) or native artery diseases were detected in six cases (6.7%) on the first graft scan (proximal anastomosis stenosis, 1: mid-graft stenosis, 3; peroneal artery stenosis, 1; popliteal artery occlusion, 1). The resting ABI was less than 0.5 in one of these cases. Vein patch angioplasty was performed on graft stenosis in two cases following the first duplex scan. In 78 cases with either normal or minimal graft/native artery stenosis (< 50%), the resting ABI were less than 0.5 in only two cases (2.6%). The first graft duplex ultrasound examinations were technically difficult or gave a poor image in 21 cases (23.3%). During the subsequent graft duplex follow-up, seven graft thromboses were demonstrated at an average of 5.9 months after surgery (1-12 months). Significant stenosis (> 50%) was demonstrated in 10 additional cases at an average of 8.5 months after surgery (1-12 months).

CONCLUSIONS

The data of the present study do not support routine peri-operative graft duplex scanning in addition to a 1-month graft duplex scan. Early postoperative resting ABI should be routinely performed. If the resting ABI is less than 0.5, an immediate duplex scan should be carried out to assess graft integrity. A long-term non-invasive graft surveillance programme is important in the detection of graft stenosis.

Expression of Hras-p21 and keratin K13 in UVR-induced skin tumors in Sencar mice

An ultraviolet radiation (UVR)-induced Sencar mouse skin carcinogenesis model was established to investigate the expression of Hras-p21 and keratin K13 in different stages of carcinogenesis, including UV-exposed nontumor skin, papillomas, squamous-cell carcinomas (SCCs), and malignant spindle-cell tumors (SCTs). Expression of Hras-p21 and K13 was examined in paraffin-embedded tumor sections by using immunohistochemical, immunofluorescent, and double staining techniques with specific antibodies. Positive Hras-p21 staining was detected in 1/3 (33%) papillomas, 24/36 (67%) of SCCs, but not in UVR-exposed nontumor skin or SCTs. Positive staining of the malignant progression marker K13 was found in 22/36 (61%) of SCCs only. Coexpression of Hras-p21 and K13 was found in 17/36(47%) SCCs. H-ras exons 1 and 2 were amplified from skin/tumor sections by using nested polymerase chain reaction (PCR). PCR-based single-strand conformation polymorphism (SSCP) analysis and gene sequencing revealed three point mutations, one in UVR-exposed nontumor skin (codon 56), and two in SCCs (codons 13 and 21). There were no clear relationships between point mutations of H-ras and the positive staining of Hras-p21 and K13. These results indicate that overexpression of ras-p21 in conjunction with aberrant expression of K13 is a frequent event in UVR-induced SCCs in Sencar mouse skin. Point mutation of the H-ras gene appeared to be a rare event in UVR skin carcinogenesis and not to be responsible for overexpression of Hras-p21.

[PCR in detecting the correlation between infection of HBV and cholelithiasis]

OBJECTIVE

To study the correlation between cholelithiasis and the infection of HBV.

METHOD

32 formalin-fixed and paraffin-embedded gallbladder samples of cholelithiasis patients and 20 gallbladder samples of non-cholelithiasis patients were investigated using the polymerase chain reaction-Ethidium bromide (PCR-EB) assay. The 52 patients were positive to HBV serologic markers.

RESULT

The results showed that HBV-DNA was found in 13 gallbladder samples of 32 cholelithiasis patients (40.63%), significantly higher than that in 3 gallbladder samples of 20 non-cholelithiasis patients (15%).

CONCLUSION

The infection of HBV and the formation of cholelithiasis are correlated.

[Cloning and sequencing of the gene for premature beta nerve growth factor]

The entire coding sequence of premature nerve growth factor (NGF) beta subunit was amplified from Genomic DNA extracted from peripheral white blood cells of Chinese by polymerase chain reaction (PCR). The PCR products were cloned into a premade T-vector (linearized plasmid pBluescript II SK (+) with a T base at 3' terminal), followed by automatic sequencing with double strand plasmids. The nucleotide sequence coding for the mature NGF is the same as that reported by Europeans, but there is a base difference within the proper region, resulting in an amino acid replacement in premature NGF.

Comparative developmental profile of the neuropeptide Y Y1 receptor gene and protein in the rat brain

Neuropeptide Y (NPY) is one of the most abundant peptides found in the mammalian central nervous system (CNS) and plays several important roles in regulating brain function. Physiological roles of NPY in the brain are mediated by at least six receptor subtypes (Y1 to Y6). In the present study, a rat Y1 receptor cRNA probe was used for in in situ hybridization experiments in order to determine the developmental profile of this receptor mRNA and to compare it with its translated protein using receptor autoradiography with the radiolabelled ligand [125I][Leu31,Pro34]PYY. The NPY Y1 receptor mRNA is expressed as early as by the 12th day of gestation while specific [125I][Leu31,Pro34]PYY binding is observed by day 14 of gestation. Thereafter, both signals steadily increased, with Y1 receptor mRNA increasing faster than its translated protein during fetal life. The in situ hybridization signals reached a plateau around birth and remained high during the first 2 post-natal weeks to display the adult distribution by the end of the 3rd post-natal week. Similarly, specific [125I][Leu31,Pro34]PYY binding constantly increased during brain maturation and reached a plateau by the end of the 3rd post-natal week. In some brain areas, such as the cerebral cortex, specific binding declined slightly before attaining its adulthood pattern. Throughout ontogenesis, the profile of both the Y1 receptor mRNA and protein was well-matched except in hypothalamic areas where relatively higher mRNA signals were observed. Taken together, these results along with previous reports describing NPY-like immunoreactivity in the early developmental rat brain, suggest that the NPY Y1 receptor may play an important role in early brain development and maturation on the basis of its very early pattern of embryonic expression.

Chronic ultraviolet exposure-induced p53 gene alterations in Sencar mouse skin carcinogenesis model

Alterations of the tumor suppresser gene p53 have been found in ultraviolet radiation (UVR) related human skin cancers and in UVR-induced murine skin tumors. However, links between p53 gene alterations and the stages of carcinogenesis induced by UVR have not been clearly defined. We established a chronic UVR exposure-induced Sencar mouse skin carcinogenesis model to determine the frequency of p53 gene alterations in different stages of carcinogenesis, including UV-exposed skin, papillomas, squamous-cell carcinomas (SCCs), and malignant spindle-cell tumors (SCTs). A high incidence of SCCs and SCTs were found in this model. Positive p53 nuclear staining was found in 10/37 (27%) of SCCs and 12/24 (50%) of SCTs, but was not detected in normal skin or papillomas. DNA was isolated from 40 paraffin-embedded normal skin, UV-exposed skin, and tumor sections. The p53 gene (exons 5 and 6) was amplified from the sections by using nested polymerase chain reaction (PCR). Subsequent single-strand conformation polymorphism (SSCP) assay and sequencing analysis revealed one point mutation in exon 6 (coden 193, C-->A transition) from a UV-exposed skin sample, and seven point mutations in exon 5 (codens 146, 158, 150, 165, and 161, three C-->T, two C-->A, one C-->G, and one A-->T transition, respectively) from four SCTs, two SCCs and one UV-exposed skin sample. These experimental results demonstrate that alterations in the p53 gene are frequent events in chronic UV exposure-induced SCCs and later stage SCTs in Sencar mouse skin.