[Chemoprotection of transfer of multidrug resistance gene into human hematopoietic progenitor cell]

OBJECTIVE

To observe the effect of the transfer of multidrug resistance gene (mdr1) into human hematopoietic progenitor cells (HPC) on the chemoprotection.

METHODS

Human CD34+ cells served as a target of mdr1 gene transfer. Retroviral vector SF-mdr containing human total length mdr1cDNA was introduced into packing cells GP-envAM12 by liposome-mediated transfection. The mdr1 gene was transduced into human CD34+ cells by retroviral supernatants of packing cells. The integration and expression of the mdr1 gene and its protein (P170) in transduced cells were determined by PCR, RT-PCR, and flow cytometry. The drug resistance of chemotherapy in transduced HPC was determined by culturing colonies.

RESULTS

The mdr1 gene was integrated and expressed in transduced CD34+ cells. The efficiency of mdr1 gene transfer was 10%-14%. Compared with untransduced controls, within a certain range of drug concentration, the number of drug-resistant colony in transduced HPC for taxol, doxorubicin, VCR and VP16 were increased by 3.6 +/- 2.1 fold, 2.9 +/- 0.3 fold, 1.9 +/- 0.4 fold, and 3.5 +/- 0.5 fold, respectively.

CONCLUSION

The transfer of the mdr1 gene into human HPC can increase the drug resistance of the transduced cells to corresponding chemotherapeutic drugs that may provide some degree of chemoprotection for HPC.

[Exploration of factors increasing transfer efficiency of retroviral mediated multidrug resistance gene (mdr1) into human CD(34)(+) cells]

OBJECTIVE

To explore factors influencing transfer of retroviral mediated multidrug resistance gene (mdr1) into human CD(34)(+) cells.

METHODS

Transduction efficiency in the presence of different combinations of cytokines and human bone marrow stromal cells plus cytokines were determined by flow cytometry (FCM). Drug resistance was evaluated by plating yields of cultured hematopoietic progenitor cells. The effect of Taxol at different concentrations on mdr1 gene transfer cells was determined by FCM.

RESULT

Transduction efficiency in the presence of SCF + FL + IL-3 was higher than that in other combinations of cytokines (SCF + IL-6 + IL-3, SCF + IL-6 + IL-3 + Tpo, SCF + IL-3). Transduction efficiency (20.5%) in the presence of bone marrow stromal cells plus cytokines (SCF + FL + IL-3) was higher than that (15.2%) without stromal cells, and the number of drug-resistant colony-forming cells was more in the former than in the latter. The percentage of CD(34)(+) cell with the gene transduction at 10 ng/ml Taxol reached 38.5%.

CONCLUSION

Human bone marrow stromal cells plus cytokines (SCF + FL + IL-3) is more effective in enhancing mdr1 gene transduction. Taxol at a certain concentration can enrich mdr1 gene transferred cells.

Conformationally constrained substance P analogues: the total synthesis of a constrained peptidomimetic for the Phe7-Phe8 region

A lactam-based peptidomimetic for the Phe7-Phe8 region of substance P has been synthesized. The synthesis used an anodic amide oxidation to selectively functionalize the C5-position of a 3-phenylproline derivative. The resulting proline derivative was coupled to a Cbz-protected phenylalanine, and an intramolecular reductive amination strategy used to convert the coupled material into a bicyclic piperazinone ring skeleton. The net result was a dipeptide building block that imbedded one of two proposed receptor bound conformations for the Phe7-Phe8 region of substance P into a bicyclic ring skeleton. The building block was then converted into a constrained substance P analogue with the use of solid-phase peptide synthesis. A similar intramolecular reductive amination strategy was used to synthesize a substance P analogue having only Phe7 constrained, and the original 3-phenylproline was converted into a substance P analogue having only Phe8 constrained. All of the analogues were examined for their ability to displace substance P from its NK-1 receptor.

Ontogenic profile of the expression of the mu opioid receptor gene in the rat telencephalon and diencephalon: an in situ hybridization study

The developmental profile of mu (mu) opioid receptor gene expression has been characterized in the embryonic, postnatal and adult rat brain by in situ hybridization histochemistry. By ED12, mu opioid receptor mRNA was detectable in the deep neuroepithelium of the cortical plate. In the developing rat central nervous system (ED13-PD40), transcripts were seen over numerous telencephalic and diencephalic structures, such as the olfactory bulb, caudate-putamen, nucleus accumbens, amygdaloid complex, hippocampal formation, hypothalamus and thalamus. In the vast majority of brain regions examined, the developmental profile of the mu opioid receptor gene expression is similar to that of its translated protein as established using receptor autoradiography. Once a hybridization signal is detected in the prenatal period, it gradually increased to reach maximal levels during the second and third postnatal weeks. By the end of the third postnatal week, mu opioid receptor mRNA levels decreased to reach amounts seen in adulthood. Our study demonstrates that mu opioid receptor gene expression is seen very early on in the embryonic rat brain with transient increases observed during the critical period of neurogenesis, neuronal migration and synaptogenesis, suggesting a role of this opioid receptor subtype in brain developmental processes.

[Establishment of a high germline competent C57BL/6J ES cell line]

Eleven ES cell lines from C57BL/6J mice were established, with the primary culture of mice embryos as feeder cells and 1 x 10(3) units Leukemia Inhibitory Factor (LIF) in the DMEM (high glucose) medium. The frequency of establishment was 9.6%. Five of these ES cell lines were demonstrated karyotypically normal with diploid composition of over 70%. They shared the characteristics of early embryonic cells: positive for alkaline phosphatase activity and oct4 gene expression. They also showed high potency to differentiate into wide types of cells in vivo. Following injection of the blastocysts, three of them showed abilities to give rise to chimeras and MESPU35 cell line was identified to have high efficiency of colonization into the germline. The clones of MESPU35 cells maintained the germline competence and the mutant clone also retained the high potency to participate into the development of embryos. MESPU35 cells can serve as a valuable vehicle for the production of mutant mice.

Expression of GIRK (Kir3.1/Kir3.4) channels in mouse fibroblast cells with and without beta1 integrins

G protein-activated K+ channel (GIRK) subunits possess a conserved extracellular integrin-binding motif (RGD) and bind directly to beta1 integrins. We expressed GIRK1/GIRK4 channels labeled with green fluorescent protein in fibroblast cell lines expressing or lacking beta1 integrins. Neither plasma membrane localization nor agonist-evoked GIRK currents were affected by the absence of beta1 integrins or by incubation with externally applied RGD-containing peptide. Mutation of the aspartate (D) of RGD impaired currents, GIRK glycosylation, and membrane localization, but the interaction with beta1 integrins remained intact. Thus, beta1 integrins are not essential for functional GIRK expression; and the GIRK-integrin interactions involve structural elements other than the RGD motif.

[Establishment of two ES cell lines with good germline contribution]

Nine embryonic stem cell lines have been established from mouse strain 129/ter. Three of the nine ES cell lines were karyotypically normal. The nine cell lines showed some difference in the growth rate and the differential competence. Chimeras were made by injecting the ES cells into C57BL/6J blastocysts, and the germline compositions of the chimeras were detected by mating them with albino ICR mice. The results indicated that ES cell line MESPU21 and MESPU22 were both highly germline-competent. Comparing with other ones, these two cell lines both were karyotypically normal and propagated fast. The tissue composition of the teratocarcinomas derived from these cell lines appeared paralle to the results of chimera production. Careful manipulation during the process of ES cell establishment was helpful to obtain good cell lines.

[Regulation of gene co-expression after bicistronic retrovirus-mediated gene transfer into human cord blood CD34+ cells]

OBJECTIVE

To compare internal SV40 early promoter with IRES of the in regulatory effect on gene co-expression after retrovirus-mediated gene transfer into human cord blood CD34+ cells.

METHODS

Based on pLXSN, vectors pLESN and pLEIN carrying EGFP and neo gene, distinguished by the in sequences between two, genes, were constructed. After liposome-mediated gene transfer into packaging cells, high-titre virus supernatant was obtained. After supernatant infection in vitro, transduced cells were cultured in CFC assay.

RESULTS

FACS analysis demonstrated that 10% of human cord blood CD34+ cell were infected in vitro. All of G418 resistant colonies demonstrated green fluorescence in LEIN group, while only 41.1% in LESN group.

CONCLUSION

IRES is superior to SV40 promoter for the guarantee of co-expression in bicistronic retrovirus-mediated gene therapy in human cord blood CD34+ cells.

[Study of conformation of serum albumin by FTIR]

This paper used the FTIR method to study the spectra of bovine serum albumin (BSA) and its solution. The secondary structure and conformation was assigned by FTIR-deconvolution analysis. The result indicated that BSA secondary structure in solid is different from in aqueous solution. As the decrease of BSA concentration from 3.241 x 10(-1) to 4.032 X 10(-2) g X mL(-1), the amide I band components at 1 609.84, 1 633.85,1 653.69, 1 681.16 and 1 694.88 cm(-1) shifted to 1 608. 24, 1 638.36, 1 656.10, 1 674.87 and 1 690.78 cm(-1), respectively, the component at 1 621.50 cm(-1) unchanged.

[Acute toxicity of Stephania cepharantha]

The acute toxicity of Stephania cepharantha was studied, LD50 of aqueous extract of its wet and dry root tuber oral were 41.4 g/kg and 22.9 g/kg respectively.

[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.

Expression of HBV Pre S1 peptide in E. coli and product characterization

HBV Pre S1 sequence is supposed to play an important role in the infection of HBV. Presence of Pre S1/anti-Pre S1 in serum has valuable clinical implications. In order to improve the study of Pre S1, Pre S1 sequence was overexpressed in E. coli as a fusion protein with MBP (Maltose-binding protein), and anti-Pre S1 antiserum was elicited in rabbits by Pre S1-MBP purified by affinity chromatography. The recombinant plasmid constructed from pMAL-cRI expressed the 106aa Pre S1 sequence at the C terminal of MBP by tac promoter. The resulting protein is about 54 kD in size. Western-blot analysis confirmed its reactivity with antiserum derived from synthetic Pre S1 peptide and serum from patients with acute hepatitis B (AHB). ELISA showed that Pre S1-MBP and Dane particles purified from AHB patient's serum reacted with antiserum against synthetic Pre S1 peptide, and this reaction was specifically inhibited by synthetic Pre S1 peptide. ELISA also demonstrated that antiserum against Pre S1-MBP reacted with synthetic Pre S1 peptide, but not with synthetic HCV peptide or HEV peptide.

[Comparative test on spawn culture materials of Poria cocos]

It saves much time, work and timber when Poria cocos spawn is made from cottonseed hulls and pine sawdust. Compared with the yields from pine wood chip, the difference is not significant.

Active site-directed double mutants of dihydrofolate reductase

Variants of dihydrofolate reductase (DHFR), which confer resistance to antifolates, are used as dominant selectable markers in vitro and in vivo and may be useful in the context of gene therapy. To identify improved mutant human DHFRs with increased catalytic efficiency and decreased binding to methotrexate, we constructed by site-directed mutagenesis four variants with substitutions at both Leu22 and Phe31 (i.e., Phe22-Ser31, Tyr22-Ser31, Phe22-Gly31, and Tyr22-Gly31). Antifolate resistance has been observed previously when individual changes are made at these active-site residues. Substrate and antifolate binding properties of these "double" mutants revealed that each have greatly diminished affinity for antifolates (> 10,000-fold) yet only slightly reduced substrate affinity. Comparison of in vitro measured properties with those of single-residue variants indicates that double mutants are indeed significantly superior. This was verified for one of the double mutants that provided high-level methotrexate resistance following retrovirus-mediated gene transfer in NIH3T3 cells.

Diagnosis of hepatitis C Virus (HCV) infection by antigen-capturing ELISA

BACKGROUND

Hepatitis C virus (HCV) is a major cause of non-A non-B hepatitis. Detection of circulating antibodies against HCV by enzyme-linked immunosorbent assay (ELISA) has provided the main approach for the diagnosis of HCV infection. Most ELISA kits use a mixture of core, NS3, NS4 and NS5 antigen as capture antigens and enzyme-labeled goat anti-human IgG as conjugate.

OBJECTIVES

To establish an ELISA system based on the antigen-capturing principle, using a recombinant chimeric polyprotein containing four HCV antigenic components as antigen.

STUDY DESIGN

HCV antigens were expressed in Escherichia coli as chimeric polyprotein either in inclusion bodies or in soluble form. Protein expressed in inclusion bodies was used as solid-phase antigen, and the antigen expressed in a soluble form was used as enzyme conjugate after being labeled with horseradish peroxidase (HRP).

RESULTS

Genes coding HCV antigens were cloned and sequenced, chimeric polyproteins containing four immunodominant components (core, NS3, NS4 and NS5) were expressed in E. coli both in soluble and in inclusion body form. These two chimeric proteins retained the antigenicity of HCV antigens. Antibody-capturing ELISA using the chimeric antigens showed a sensitivity of 97% (97/100) and a specificity of 98% (97/99) using the reference panel from the National Institute for the Control of Pharmaceutic and Biological Products of China (NICPBC); the same assay showed a sensitivity of 97.9% (48/49) and a specificity of 100% (43/43) using the self-established reference panel. Antigen-capturing ELISA was set up using the antigen labeled with horseradish peroxidase as conjugate, and was shown to be as sensitive as (97.9%) and more specific than (100%) antibody-capturing ELISA using the reference panel in this work. The antigen-capturing ELISA also showed a high accordance (98.9%) with UBI HCV enzyme immunoassay (EIA) 4.0 kits (United Biomedical Inc. USA).

CONCLUSION

Antigen-capturing ELISA provided a convenient, sensitive and more specific approach for the diagnosis of hepatitis C virus infection.

The weaver mutation changes the ion selectivity of the affected inwardly rectifying potassium channel GIRK2

The weaver mutation in mice has recently been identified as a single base-pair mutation in the Girk2 gene, which encodes a G-protein-activated inwardly rectifying potassium channel, GIRK2. The mutation results in a Gly to Ser substitution at residue 156, in the putative pore-forming region of the potassium channel. In the present study, we used Xenopus oocytes to express mutant GIRK2, and to characterize the effects of the mutation on the channel. The mutation results in a loss of the normal high selectivity for K+ over Na+, with little effect on other channel properties such as activation by the mu opioid receptor. The resulting increase in basal Na+ permeability causes a marked depolarization of oocytes expressing the mutant GIRK2 protein. This result was observed even when the mutant GIRK2 was coexpressed with GIRK1, a situation more analogous to that seen in vivo. Thus, the increased Na+ permeability and resulting depolarization may contribute to the pathology of cerebellar granule cells and substantia nigra dopaminergic neurons observed in the weaver mice.

Recurrent varicose veins after short saphenous vein surgery: a duplex ultrasound study

Recurrent venous reflux in the popliteal fossa of patients with recurrent varicose veins following short saphenous vein surgery was assessed in 70 limbs using a duplex scanner. Incompetence of the short saphenous vein was found to be the main source (61%) of venous reflux in the popliteal fossa (43/70). The recurrence or persistence of the short saphenous vein was subdivided into four types: an intact saphenopopliteal junction, as well as an intact short saphenous vein in 20 limbs (type I): varicosities in the popliteal fossa communicating with a short saphenous vein stump in 11 limbs (type II); a residual short saphenous vein communicating with the popliteal vein via a tortuous recurrent vein in eight limbs (type III); and a segment of residual short saphenous vein with no communication with the popliteal vein in four limbs (type IV). Incompetence of a gastrocnemius vein was involved in 24 cases (34%), an incompetent popliteal area vein in one (1.4%), popliteal vein incompetence in 15 (21%), and popliteal fossa varicosities communicating with the long saphenous system in two (3%). Of 12 limbs tested pre- and postoperatively, a high termination of the short saphenous vein was demonstrated in four of seven residual incompetent short saphenous veins. Duplex scanning is recommended to assess recurrent venous reflux in the popliteal fossa. It can be used to determine the level of an incompetent saphenopopliteal junction and the level of the termination of any other incompetent vein in the management of varicose veins recurring after a short saphenous vein operation.

Combined semiclosed iliac endarterectomy and distal arterial reconstruction for multilevel arterial disease

Semiclosed iliac endarterectomy in combination with an infrainguinal vascular reconstruction has been used over the past decade in the treatment of lower-limb ischaemia. Although the early results of this combination of operations were known, the durability of the external iliac endarterectomy had not been assessed and so an effort was made to review all surviving patients by duplex scanning. Between 1985 and 1993, 48 patients (51 limbs) underwent combined semiclosed iliac endarterectomy and infrainguinal vascular reconstruction for iliac and femoropopliteal occlusive disease. Some 49% of operations were performed for limb salvage. An iliofemoral bypass graft was required twice because of failure of the endarterectomy. A variety of distal arterial reconstructions was employed. One patient required a major amputation and there were two deaths. Mean (s.d.) ankle/brachial indices (ABI) rose from 0.54 (0.14) to 0.85 (0.25) after surgery. Some 85% of the patients who underwent operation for claudication became symptom free; 83% of patients who underwent operation for limb-threatening ischaemia became symptom free or improved to mild claudication during an average of 29 months follow-up. During the follow-up period five patients underwent a further procedure because of restenoses of the external iliac artery. A duplex scanning study was performed in 22 of the 51 limbs an average of 36 months after surgery. External iliac artery stenotic lesions were found in the area of the endarterectomy in three patients. Endarterectomy of the external iliac artery from the groin is an alternative for some patients with iliac arterial disease. In a patient scheduled for an infrainguinal bypass, when an unexpectedly greater degree of athermoma is found at operation in the common femoral and external iliac arteries, this operation may be performed. The durability of the operation as assessed by follow-up duplex scan is quite acceptable.

Expression of the neuropeptide Y Y1 receptor mRNA in the human brain: an in situ hybridization study

Using cRNA in situ hybridization, the regional distribution of mRNA encoding the human Y1 receptor was investigated in the normal human brain and compared with the autoradiographic distribution of putative Y1/[125I][Leu31,Pro34]PYY binding sites. Surprisingly, relatively high levels of Y1 receptor mRNA, distributed in a ty laminar fashion, were detected in the frontal and temporal cortices; laminae I, IV and VI were particularly enriched. The claustrum and nucleus of the medial geniculate body also revealed high levels of Y1 receptor mRNA signals. Moderate levels of specific hybridization were detected in the caudate nucleus, putamen, nucleus accumbens, amygdaloid nuclei, and arcuate and paraventricular nuclei of the hypothalamus. In all these regions, only very low levels of specific [125I][Leu31,Pro34]PYY binding were detected with the exception of the dentate gyrus of the hippocampal formation which expressed rather high levels of both the Y1 receptor mRNA and its translated protein. Accordingly, the human brain can express the Y1 receptor mRNA but this may not necessarily translate into a functional receptor as revealed by low specific binding levels observed in most regions.

Functional expression and signaling properties of cloned human parathyroid hormone receptor in Xenopus oocytes. Evidence for a novel signaling pathway

Expression of human parathyroid hormone receptor (hPTHR) was obtained in Xenopus oocytes. Receptor function was detected by hormone stimulation of endogenous Ca2+-activated Cl- current. This current was blocked by injected, but not by extracellular, EGTA, confirming that the hPTHR activates cytosolic Ca2+ signaling pathways. PTH responses were acutely desensitized but were regained in 6 12 h. Injection of cAMP or analogues had no effect on either responsiveness or desensitization to hPTH. The hPTH response was more sluggish than seen with serotonin 5-hydroxytryptamine (5-HT2C) receptor. In oocytes co-expressing both hPTHR and 5-HT2C receptors, homologous desensitization was seen, but cross-desensitization was not observed. Injection of inositol 1,4,5-trisphosphate (InsP3) elicited a fast inward current similar to that induced by serotonin, and complete cross-desensitization occurred between the InsP3 and 5-HT2C responses. Desensitization by hPTH did not affect responses to either InsP3 or serotonin, but cells desensitized to injected InsP3 still responded strongly to PTH. Oocytes did not respond to either cADPR or NAADP+, but NADP+ and analogues were found to be potent inhibitors of PTH signaling. We suggest that PTH cytosolic Ca2+ signaling in oocytes either involves a novel signaling system or proceeds through a Ca2+ compartment whose responsiveness is regulated in a novel way.

Outcome of patients with symptomless carotid bruits: a prospective study

Knowledge of the natural history of symptomless carotid artery disease is important in determining the best preventative treatment for symptom-free patients. To document the progression of carotid artery disease and the clinical course of a symptomless population, 336 patients with symptom-free carotid bruits were prospectively followed up initially with oculoplethysmography and subsequently with duplex scanning. During a mean follow-up of 4.87 years, eight patients (2.4%) suffered a stroke. Thirty-seven (11.0%) experienced transient ischaemic attacks (TIAS). The cumulative event rate (TIA plus stroke) was 13.4% (45/336). The annual event rates were 0.48% for stroke, 2.26% for TIA and 2.75% for all ischaemic events. In a subgroup of 69 high-grade carotid stenoses (80-99%), 31 carotid endarterectomies were performed before the development of a TIA or stroke and 21 after the development of symptoms, while 17 lesions were followed-up non-operatively. The total event rate (TIA and stroke) was significantly greater in the non-operated compared with the operated arteries (51.0% versus 6.4% at 5 years, P=0.0034). However, most of the events which occurred in the non-operated group were TIAs (85.7%) rather than stroke. There was no difference In the death rate of the two groups (P>0.05). Review of serial duplex studies performed on 540 carotid arteries revealed that 382 arteries (70.7%) remained unchanged and 158 (29.3%) showed disease progression. Forty-four of the 540 arteries became symptomatic (TIA or stroke). In 29 of the 44, the event occurred without any change in diameter of the artery, while in 15 there was a change of at least one category greater stenosis. In 39 patients, the stenosis was at least 40% and in five the stenosis was under 40%. Nine events occurred in the patients with severe contralateral carotid stenoses (>60%). The incidence of TIA (32.2%), stroke (6.8%) and death (18.6%) was higher in patients with internal carotid artery stenoses in excess of 80% than in those with lesions between 0 and 79% stenosis (P<0.0001, P= 0.0367 and P=0.0236, respectively). In this study the incidence of cerebrovascular events was higher in patients with high-grade internal carotid artery disease, and the preservation of neurological status in patients with symptomless high-grade carotid artery stenosis was improved by carotid endarterectomy, although the overall mortality remained unchanged.

Expression of multidrug resistance-associated protein (MRP) mRNA in blast cells from acute myeloid leukemia (AML) patients

A specific and quantitative reverse-transcription polymerase chain reaction (RT-PCR) assay was developed for measuring the mRNA of the multidrug resistance-associated protein (MRP). A region corresponding to bp 3897-4471 of MRP cDNA is amplified, which encompasses approximately half of the second nucleotide-binding domain (NBD2). In two multidrug resistant (MDR) sublines of the HL-60 human acute myeloid leukemia (AML) cell line which overexpress MRP but not P-glycoprotein, the assay detects elevated levels of MRP mRNA (4- to 8-fold) relative to the drug-sensitive parental cells (designated HL-60/W). Blast cells from 24 patients with AML were also studied for MRP expression using this RT-PCR method. Expression of MRP was normalized for that of beta-actin in the blast cells, which was also determined by RT-PCR. All of these blast cell samples had MRP expression that was detectable after 35 PCR cycles. Eighteen of these patients samples had levels of expression of MRP mRNA equal to or less than that expressed by HL-60/W cells. In six patient blast cell specimens, the expression of MRP mRNA was up to 1.7-fold higher than that of HL-60/W cells. In 21 specimens, the steady-state intracellular accumulation of daunorubicin (1 microgram/ml, 3h) was also determined. The blast cells with MRP mRNA expression higher than HL-60/W had a lower median accumulation of daunorubicin compared to those whose MRP expression was less than HL-60/W, suggesting a functional defect in drug transport in the cells with higher MRP expression; a similar trend toward lower daunorubicin accumulation was also noted in the one-third of samples that displayed the highest expression of MDR1 mRNA (also determined by RT-PCR). These studies illustrate the range of expression of MRP in AML blast cell specimens. The identification of MRP overexpression in MDR AML cell lines and in some AML patient blast cells with low intracellular daunorubicin accumulation warrants further study of MRP as a component of clinical drug resistance in AML.

Expression of the neuropeptide Y Y1 receptor in human embryonic kidney 293 cells: ligand binding characteristics, in situ hybridization and receptor autoradiography

The human neuropeptide Y Y1 receptor cDNA was transfected into human embryonic kidney 293 (HEK 293) cells and used to determine the selectivity of newly developed Y1 and Y2 radioligands in a model which expresses a single NPY receptor subtype. The Y1 receptor probe, [125I][Leu31,Pro34]PYY, binds with high afinity (KD of 0.4-0.6 nM) to Y1-transfected HEK 293 cells whereas the Y2 radioligand, [125I]PPY3-36 failed to demonstrate any significant labelling. Only non-selective (PYY) or selective Y1 receptor agonists behaved as potent competitors for [125I][Leu31,Pro34]PYY binding in transfected cells. Additionally, the efficacy of the transfection method used was evaluated at both the transcriptional and translational levels. In situ hybridization revealed the heterogeneous distribution of the NPY Y1 receptor mRNA expressed in transfected HEK 293 cells. Similarly, the levels of NPY Y1 binding sites per transfected cell varied as shown using [125I][Leu31,Pro34]PYY receptor autoradiography. Taken together, these results demonstrate that HEK 293 cells transfected with the NPY Y1 receptor cDNA expressed both the related receptor mRNA and protein albeit at different levels depending upon each transfected cell. Additionally, these data further establish the selectivity of the newly developed Y1 and Y2 radioligands.