WIM/WISE NMR studies of chain dynamics in solid polymers and blends

Wideline separation (WISE) NMR with window-less isotropic mixing (WIM) is developed as a method to study the dynamics of polymers and blends. This experiment is designed to measure the dynamics of polymers through the proton lineshapes that are correlated with the carbon chemical shifts in two-dimensional NMR experiments. If the atoms experience large amplitude fluctuations that are fast compared to the dipolar broadening, then the proton lines will be narrowed relative to rigid solids. We have modified the WISE experiment by replacing the cross polarization step with WIM to quench spin diffusion during the cross polarization so that the proton linewidths can be directly related to the chain dynamics. Two-dimensional WIM/WISE has been used to measure the main-chain and side-chain dynamics in poly(n-butyl methacrylate) and blends of polystyrene and poly(vinyl methyl ether).

Crystal structure of beta-ketoacyl-acyl carrier protein synthase III. A key condensing enzyme in bacterial fatty acid biosynthesis

Beta-ketoacyl-acyl carrier protein synthase III (FabH), the most divergent member of the family of condensing enzymes, is a key catalyst in bacterial fatty acid biosynthesis and a promising target for novel antibiotics. We report here the crystal structures of FabH determined in the presence and absence of acetyl-CoA. These structures display a fold that is common for condensing enzymes. The observed acetylation of Cys(112) proves its catalytic role and clearly defines the primer binding pocket. Modeling based on a bound CoA molecule suggests catalytic roles for His(244) and Asn(274). The structures provide the molecular basis for FabH substrate specificity and reaction mechanism and are important for structure-based design of novel antibiotics.

Study of thrombopoietin for gene therapy of thrombocytopenia

Thrombopoietin (TPO) is likely to he a potent, specific and reliable medication in the treatment of thrombocytopenia. A TPO-highly-expressed plasmid pcDNA3-TPO was constructed and a primary study was made on the expression of TPO cDNA in vitro and gene transfer study for thrombocytopenia in vivo. rhTPO showed complete and stable bioactivity by a series of indicators. High expression of TPO was detected in plasma from healthy mice or thrombocytopenia mice model receiving direct intramuscular injection of pcDNA3-TPO. And the platelet level of healthy mice peaked to 1.9-fold of baseline. Mice with CTX-induced thrombocytopenia achieved profound nadirs, acceleration of recovery, even 1.8-2.0-fold supranormal levels of peripheral platelet counts. The results offered experimental support for clinical application of gene therapy for thrombocytopenia via direct intramuscular injection of TPO cDNA.

Molecular basis for triclosan activity involves a flipping loop in the active site

The crystal structure of the Escherichia coli enoyl reductase-NAD+-triclosan complex has been determined at 2.5 A resolution. The Ile192-Ser198 loop is either disordered or in an open conformation in the previously reported structures of the enzyme. This loop adopts a closed conformation in our structure, forming van der Waals interactions with the inhibitor and hydrogen bonds with the bound NAD+ cofactor. The opening and closing of this flipping loop is likely an important factor in substrate or ligand recognition. The closed conformation of the loop appears to be a critical feature for the enhanced binding potency of triclosan, and a key component in future structure-based inhibitor design.

Interaction of tyrosyl aryl dipeptides with S. aureus tyrosyl tRNA synthetase: inhibition and crystal structure of a complex

Tyrosyl aryl dipeptide inhibitors of S. aureus tyrosyl tRNA synthetase have been identified with IC50 values down to 0.5 microM. A crystal structure of the enzyme complexed to one of the inhibitors shows occupancy of the tyrosyl binding pocket coupled with inhibitor interactions to key catalytic residues.

Cooperative structural dynamics and a novel fidelity mechanism in histidyl-tRNA synthetases

The crystal structure of the Staphylococcus aureus histidyl-tRNA synthetase apoprotein has been determined at 2.7 A resolution. Several important loops in the active site either become disordered or adopt very different conformations compared to their ligand-bound states. These include the histidine A motif (Arg257-Tyr262) that is essential for substrate recognition, a loop (Gly52-Lys62) that seems to control the communication between the histidine and ATP binding sites, the motif 2 loop (Glu114-Arg120) that binds ATP, and the insertion domain that is likely to bind tRNA. These ligand-induced structural changes are supported by fluorescence experiments, which also suggest highly cooperative dynamics. A dynamic and cooperative active site is most likely necessary for the proper functioning of the histidyl-tRNA synthetase, and suggests a novel mechanism for improving charging fidelity.

The sleep disorder canine narcolepsy is caused by a mutation in the hypocretin (orexin) receptor 2 gene

Narcolepsy is a disabling sleep disorder affecting humans and animals. It is characterized by daytime sleepiness, cataplexy, and striking transitions from wakefulness into rapid eye movement (REM) sleep. In this study, we used positional cloning to identify an autosomal recessive mutation responsible for this sleep disorder in a well-established canine model. We have determined that canine narcolepsy is caused by disruption of the hypocretin (orexin) receptor 2 gene (Hcrtr2). This result identifies hypocretins as major sleep-modulating neurotransmitters and opens novel potential therapeutic approaches for narcoleptic patients.

[Experience of endoscopic sinus operation on 74 cases]

OBJECTIVE

To improve the curative effect of endoscopic sinus operation.

METHOD

The clinical data of nasal cavity and nasal sinus via endoscopic sinus operation on 74 cases (115 sides) were in summary. Of those 74 cases, 65 were followed-up over six mothes.

RESULT

It showed that 44 cases were cured, 18 were improved, 3 were ineffective. The effective rate was 95.4%. The disappearance rate of four symptons-nasal obstruction, headache, purulent nasal discharge and loss of smelling was 95.2%, 92%, 66.7% and 42.5%, respectively. The serious operative complication was absent.

CONCLUSION

It helped to raise thd effect of anesthetization to apply nasal cavity surface anesthesia, nerve block anesthesia. Paying attention to the distinguish of dissection label can help to decrease the occurance of the serious complication of the sinus ethmoidal operation. The operation which was alternatively conducted between endoscope and cavascope, according to the operation requirement, can be carried out more thoroughly and more safely. Cleaning the operation cavity after operation can promote healing.

[Study of histopathology of endometrium following termination of early pregnancy using mifepristone]

OBJECTIVE

To explore the causes of abnormal uterine bleeding following termination of early pregnancy using mifepristone.

METHODS

19 specimens were obtained by curettage on the day immediately after expulsion of gestational sac, 40 specimens on the 7th postabortal day and 20 specimens during 2-12 weeks after induced abortion using mifepristone respectively. The histopathologic changes of the specimens were observed by HE staining, and the expression of human choronic gonadotropin (hCG) and human placental lactogen (hPL) by immunohistochemical studies as well as phloxine-tartrazine staining and Gordon Sweets staining.

RESULTS

It showed that decidua shedding retarded, especially basal decidua. Immunohistochemical studies demonstrated the trophoblasts were still active and might affect pathological changes of local endometrium. The specific granules of endometrial granulocytes disappeared, together with disintegration of the reticular fibers. But in the group which curettage was indicated for abnormal bleeding 2 weeks after abortion, the main cause was incomplete abortion.

CONCLUSIONS

In addition to incomplete abortion, the retardation of decidua shedding and the impairment of endometrium regeneration were responsible for the abnormal uterine bleeding following termination of early pregnancy using mifepristone. The incomplete dissolution of the reticular fibers in basal decidua may induce decidua shedding retardation and incomplete abortion.

Purification and characterization from rat kidney membranes of a novel platelet-activating factor (PAF)-dependent transacetylase that catalyzes the hydrolysis of PAF, formation of PAF analogs, and C2-ceramide

We have previously identified two enzyme activities that transfer the acetyl group from platelet-activating factor (PAF) in a CoA-independent manner to lysoplasmalogen or sphingosine in HL-60 cells, endothelial cells, and a variety of rat tissues. These were termed as PAF:lysoplasmalogen (lysophospholipid) transacetylase and PAF:sphingosine transacetylase, respectively. In the present study, we have solubilized and purified this PAF-dependent transacetylase 13,700-fold from rat kidney membranes (mitochondrial plus microsomal membranes) based on the PAF:lysoplasmalogen transacetylase activity. The mitochondria and microsomes were prepared and washed three times, then solubilized with 0.04% Tween 20 at a detergent/protein (w/w) ratio of 0.1. The solubilized fractions from mitochondria and microsomes were combined and subjected to sequential column chromatographies on DEAE-Sepharose, hydroxyapatite, phenyl-Sepharose, and chromatofocusing. The enzyme was further purified by native-polyacrylamide gel electrophoresis (PAGE) and affinity gel matrix in which the competitive inhibitor of the enzyme, 1-O-hexadecyl-2-N-methylcarbamyl-sn-glycero-3-phosphoethanolamine was covalently attached to the CH-Sepharose. On SDS-PAGE, the purified enzyme showed a single homogeneous band with an apparent molecular mass of 40 kDa. The purified enzyme catalyzed transacetylation of the acetyl group not only from PAF to lysoplasmalogen forming plasmalogen analogs of PAF, but also to sphingosine producing N-acetylsphingosine (C2-ceramide). In addition, this enzyme acted as a PAF-acetylhydrolase in the absence of lipid acceptor molecules. These results suggest that PAF-dependent transacetylase is an enzyme that modifies the cellular functions of PAF through generation of other diverse lipid mediators.

[An experimental investigation of inhibition of interferon on lens epithelial cell growth in vitro]

OBJECTIVE

To investigate the inhibition of alpha-interferon (alpha-IFN) and gamma-interferon (gamma-IFN) on rabbit lens epithelial cell (RLEC) proliferation in vitro and their effective concentrations.

METHODS

The second and third passage of RLEC were used for assay. Various concentrations of alpha-IFN or gamma-IFN were added into the culture medium and RLECs were exposed to these drugs. After 24 and 72 hours, the inhibition of RLECs was determined by counting the RLEC numbers on a counting plate and MTT colorimetric assay.

RESULTS

Alpha-IFN and gamma-IFN may reduce the proliferation of RLECs at the concentration of 10(3) - 10(4) IU/ml. The inhibition of gamma-IFN was a little stronger than that of alpha-IFN.

CONCLUSION

The experiment provides a scientific basis for selection of drugs to prevent after cataract.

[Simultaneous determination of europium and copper in rare earth oxide by use AAS-PLS method]

Partial least squares regression was used to compensate for spectral "overlap" interference of Eu 324. 753 nm with Cu 324.754 nm in atomic absorption spectrometry. We could only use the copper element hollow-cathode lamp to simultaneous determine Eu and Cu in synthetic samples and rare earth oxide, and obtained satisfactory results.

[Effects of apoptosis of synovial lining cells on pathogenesis of osteoarthropathy]

The author counted synovial lining cells(SLCs) of apoptosis in the joints of osteoarthropathy(OA, 12 cases) and control(10 cases) patients. The counts of apoptotic SLC were investigated by gel electrophoretic analysis of DNA extracted from synovium. The apoptotic index(AI) of SLCs in OA(2.04%) was obviously higher than that in controls(0.60%); electrophorectogram of DNA revealed a characteristic ladder pattern of DNA fragments at 200 bp in the OA group. We conclude that apoptosis can be found in synovial lining layer, and the AI of SLCs in the OA group is much higher than that in the control group, implying the high turn-over rate of SLCs in OA; the increasing apoptosis of SLCs may increase lesion factors retained in joints and cause the injury of articular cartilage.

[Effect of acetylcholine receptor antibody derived from myasthenia gravis on the rat central neuronal nicotinic acetylcholine receptor]

Immunoreaction between acetylcholine receptor antibody (AChRab) derived from myasthenia gravis (MG) and neuronal nicotinic acetylcholine receptor (AChR) and the action of AChRab on rat brain stem auditory transmission were investigated by immunocytochemistry and brain stem auditory evoked potential (BAEP) in a search for abnormalities indicating central nervous system (CNS) involvement in this disorder. 25 microliters of AChRab were injected into the ventricular system of rats once every 48 hours for periods of up to a week BAEP examination was taken before and after injection of AChRab. Immunocytochemical investigation of the rat brain sections provided evidence that the neuronal nicotinic AChR like immunoreactivity is widely distributed throughout the rat CNS such as cerebral cortex, hippocampus, motor neurons in brain stem, auditory nucleus cerebellar cortex, etc. Analysis of the immunocytochemical results showed that the distribution property of AChRab in rat CNS correlated well with known neuronal nicotinic AChR subtypes e.g., alpha 7 and alpha 4. BAEP inter peak latency was significantly prolonged in rats after injection of AChRab as compared with the control rats and the rats prior to injection of AChRab. The results indicated that cerebroventricular administration of AChRab not only cause dysfunction of brain stem auditory transmission but also leads to development of experimental autoimmune MG symptoms. It is concluded that AChRab influences the rat brain stem auditory transmission and it is suggested that the pathogenic effect of AChRab is not only limited at neuromuscular junction, but also involves the central neuronal nicotinic AChR.

Antienvelope antibodies are protective against GBV-C reinfection: evidence from the liver transplant model

An assay for the detection of antibody against the second envelope (E2) protein of GB virus type C (GBV-C) has been developed. Early reports suggested that this antibody was a marker of viral clearance, yet it is unknown whether anti-E2 is protective against further GBV-C infection. The primary aims were to determine (1) if posttransplantation immunosuppression alters the prevalence of anti-E2; and (2) if anti-E2 positivity pretransplantation protects against acquisition of GBV-C infection posttransplantation. Fifty-four recipients who underwent orthotopic liver transplantation for end-stage liver disease of nonviral etiologies were tested for GBV-C RNA using a PCR-based assay and anti-E2 antibodies by an enzyme-linked immunoassay. Anti-E2 was present in 35% and in 46% of patients pre- and posttransplantation, respectively. Anti-E2 positivity pretransplantation was strongly associated with anti-E2 positivity after transplantation (P < 0.001); 83% of patients with anti-E2 prior to transplantation remained anti-E2-positive after transplantation. A negative association between presence of GBV-C viremia and presence of anti-E2 was found in all patients tested either prior to or following transplantation (P=0.03). Acquisition of GBV-C infection was significantly lower in patients who were anti-E2-positive prior to transplantation (2/13) compared to those who were anti-E2-negative (12/26) (P=0.05). It is concluded that immunosuppression does not reduce the prevalence of anti-E2 after transplantation in those who are seroreactive prior to transplantation. Anti-E2 appears to be a neutralizing antibody whose presence at the time of liver transplantation protects against acquisition of GBV-C infection in the peritransplantation period.

[Vitrectomy for treatment of retinal detachment caused by macular hole]

OBJECTIVE

To evaluate the effect of vitrectomy and autoserum for treatment of retinal detachment caused by macular hole.

METHODS

19 eyes with retinal detachment caused by macular hole were treated with gas tamponade (C(3)F(8)). The follow-up periods ranged from 6 to 24 months. In the case whose macular hole failed to heal, removal of the remains of prefoveal membrane and/or scratching at the retinal pigment epithelium (RPE) and placing autoserum for 7 minutes in the macular hole were performed.

RESULTS

Closure of macular hole was obtained in 15 eyes (80%). The postoperative visual acuity was 0.05 - 0.4. Macular hole failed to heal in 4 eyes. In one eye the remains of prefoveal membrane were removed; in another 3 eyes, in the macular hole scratching at the retinal pigment epithelium (RPE) and placing autoserum were performed and C(3)F(8) tamponade was used. Anatomical cure was obtained in all the 4 eyes. The final visual acuity was 0.1 or better.

CONCLUSION

The findings show that removal of prefoveal membrane is imperative. Scratch at RPE with placement of autoserum in the macular hole is effective for the macular hole which has failed to respond to conventional vitrectomy with air tamponade.

[Effect of melatonin on mean blood pressure and heart rate in morphine withdrawal rats]

The model of morphine dependent rats was established by gradually increasing the doses of morphine by subcutaneous injection(from 5 mg.kg-1 to 50 mg.kg-1, 5 days). The effects of melatonin(MT) on the mean arterial blood pressure(mABP) and heart rate(HR) were studied in naloxone-precipitated rats. MT was found to inhibit the hypertention and tachycardiac syndromes in morphine withdrawal rats in dose-dependent manner. The concentration of serum norepinephrine(NE) was shown to be decreased by MT. Moreover, regitine was shown to inhibit the increase of mABP in morphine withdrawal rats, but can not inhibit the increase of HR. These results suggest that the inhibitory effect of MT on hypertension and tachycardiac syndromes in morphine withdrawal rats may be mediated by the inhibitory effect of the drug on the sympathetic system.

[Bone scintigraphy in evaluating revascularization of the heat-devitalised autografts in adult dogs]

OBJECTIVE

To establish an animal model of microwave hyperthermic devitalization of long bones and compare bone scintigraphy of the devitalised bone with pathologic examination.

METHOD

16 Mongrel adult dogs were used. Enght 8 cm of one femur of each dog was exposed and isolated by heat-proof material. Two microwave antennas were inserted into the medullary cavity at a distance of 2.5 cm, and the bone was heated intermittently to maintain a surface temperature of 50 degrees C to 60 degrees C for 30 minutes. Bone scintigraphy was carried out at different postoperative time, combined with tetracycline labeling, microangiography with Indian ink and HE staining.

RESULT

About 5 cm - 6 cm of segmental femur was deprived of blood supply after devitalization which was confirmed by microangiography and negative labeling of tetracyclines. At two weeks, the devitalised bone demonstrated a cold region on the scintiscan and no revascularization in microangiography. 12 - 16 weeks after the operation, partial devitalised bone was revascularized and HE staining showed widel bone resorption and minimum formation of new bone. However, the radionuclide uptakes of the devitalised segments were greater than those of the normal femurs. At one year, the devitalised segment was well (not completely) revascularised and showed evident appositional new bone formation. The scintigraphic bone-imaging was slightly lower than that of the normal femur.

CONCLUSION

A strong positive scintiscan in early stage might demonstrate a good potential of revascularization of the heat-devitalised cortical bone rather than its viability. And the scintiscans of long-term follow-up more than one year should be more informative.

[The inhibitory effect of melatonin on morphine withdrawal syndromes and serum monoamines in morphine dependent mice]

OBJECTIVE

To observe the inhibitory effect of melatonin on morphine withdrawal syndromes and serum monoamines in morphine dependent mice.

METHODS

A physical dependent model in mice was established by subcutaneous injection of morphine. The intensity of withdrawal syndromes was evaluated according to the jumping latency and jumping times. The concentration of serum monoamines was detected with HPLC-ECD.

RESULTS

The physical withdrawal syndromes in morphine dependent mice were inhibited partly by four different doses (25, 50, 100, 200 mg/kg) of melatonin and showed a significant dose-dependent manner. The increased concentration of serum norepinephrine and dopamine in morphine-dependent mice could be reduced by large dose (100 mg/kg) of melatonin.

CONCLUSION

The jumping withdrawal syndromes and serum monoamiues in morphine-dependent mice could be inhibited partly by melatonin.

Antibodies against the GB virus C envelope 2 protein before liver transplantation protect against GB virus C de novo infection

GB virus C (GBV-C) is a newly discovered RNA virus related to the Flaviviridae family. Although GBV-C is not yet associated with any cause of liver disease, a humoral immune response against the GBV-C envelope 2 (E2) protein has been observed. Therefore, we studied the prevalence and clinical relevance of GBV-C RNA and anti-E2 antibodies in patients undergoing orthotopic liver transplantation (OLT). In addition, we tested whether the prevalence of anti-E2 antibodies may protect against GBV-C infection. Of the 182 liver recipients included in this study, 117 of these were evaluated for GBV-C recurrence or de novo infection. GBV-C RNA was detected in sera or plasma using single-tube, reverse-transcriptase polymerase chain reaction, and anti-E2 antibody was detected by enzyme immunoassay (EIA). Cumulative patient and graft survival was tested by using Kaplan-Meier analysis. The independence of prognostic values was assessed by using Cox regression analysis. Before OLT, GBV-C RNA and anti-E2 were detected in 4.0% to 28.6% and 10.0% to 68.8%, respectively, of patients suffering from different forms of chronic liver diseases. GBV-C reinfection after OLT was determined in 85.7%. Of the patients without evidence of exposure to GBV-C before OLT, 30 of 65 (46.2%) became GBV-C RNA positive after OLT. None of the 38 patients who were anti-E2 antibody positive before OLT became GBV-C RNA positive after OLT. Neither patient nor graft survival was significantly affected by the presence of either GBV-C RNA or anti-E2 antibody before OLT. Our data indicate that 1) GBV-C RNA positive patients have a high risk of reinfection after OLT, and 2) the presence of anti-E2 antibodies before OLT is associated with an absence of GBV-C infection after OLT, which may indicate a protective role of anti-E2 antibodies.

Expression and regulation of hFIX minigene and cDNA driven by beta-casein gene in mouse mammary gland

Mammary gland specific expression vectors for human clotting factor IX (hFIX) and LacZ reporter gene driven by bovine beta-casein gene were constructed. Vectors were packaged by stearylamine (SA) liposome and were transferred to lactating mice via tail vein. Both hFIX and Lac2 gene could be expressed in the mammary gland of the treated mice. The highest production of hFIX protein was 80.28 ng per mL milk, and more than 85% of hFIX protein appeared to be gamma-carboxylation and biologically active. The results suggested that the 2.0 kb sequence of beta-casein gene including promoter, exon 1 was effective to drive hFIX gene expression in mammary gland and intron 1 of beta-casein gene had an effect on the tissue specific expression. The expression level in mouse milk injected with hFIX minigene vector containing hFIX endogenous intron 1 was increased by above 3 times of that injected with hFIX cDNA vector.

Role of p53 in aziridinylbenzoquinone-induced p21waf1 expression

Quinones are the second largest family of anticancer drugs clinically used in the United States. However, their exact mode of action at the cellular and molecular level is not completely understood. We have shown earlier that the quinone 3,6-diaziridinyl-1,4-benzoquinone (DZQ) leads to the increased expression of p21waf1/cip1/sdi1 protein, an inhibitor of cyclin-dependent kinases. Because p21 has been established as an important negative regulator of the cell cycle, we further investigated the molecular basis of p21 induction by DZQ. Here we report that the induction of p21 by DZQ is regulated at the transcriptional level, and requires the activation of p53, a tumor suppressor protein. In cells that lack functional p53 protein, DZQ-mediated p21 induction is greatly diminished. However, the introduction of a wild type p53 gene into p53-negative cells restores the strong DZQ-inducibility of p21. Restoration of wild type p53 status in HL60 myeloid leukemia cells significantly increases the cells' sensitivity to the cytotoxic effects of DZQ. Thus, our results indicate that the p53-p21 pathway may play a central role in mediating the gene-regulatory and cytotoxic effects of aziridinylbenzoquinones.

[The effect of nimodipine on retinal blood flow in pregnancy induced hypertension]

OBJECTIVE

To assess the effects of nimodipine on retinal blood flow in patients with pregnancy induced hypertension (PIH).

METHODS

Fourteen patients were studied with color flow Doppler before and after 30 mg nimodipine administered orally, while other fourteen patients received intravenous magnesium sulfate as control group. Central retinal artery flow velocity waveforms were measured and pulse index (PI) were calculated.

RESULTS

Nimodipine reduced the central retinal artery PI significantly from 0.92 +/- 0.14 to 0.75 +/- 0.22. It also reduced systolic blood pressure from 20.7 +/- 2.5 kPa to 19.8 +/- 1.5 kPa and diastolic blood pressure from 14.4 +/- 2.3 kPa to 13.6 +/- 1.9 kPa.

CONCLUSIONS

Nimodipine may dilate central retinal arteries. Changes in pulsatility index in retinal arteries maybe indicative of similar changes in other cerebral vessels. Nimodipine may be another choice of PIH therapy.

[Effect of yuanhua on isolated uterine strips in unpregnant rats]

OBJECTIVE

To explore the mechanism on the effect of Yuanhua on the contractile activity of isolated uterine strips in rats under artificial oestrum.

METHOD

Isolated strips were suspended in a tissue chamber in which Yuanhua was added with some antagonists of inhibitors or without.

RESULT

Yuanhua could excite the uterine smooth muscle strips in a dose-dependent manner, but atropine, phentolamine, hexamethonium and diphenhydramine could not inhibit this exciting action. This exciting effect could be inhibited completely by verapamil and decreased by indomethacin(inhibitor of prostaglandin synthase).

CONCLUSION

The exciting effect of Yuanhua on un-pregnant rats in vitro might be related to an action on the cell membrane Ca2+ channel as well as to a partial stimulation of synthesis and release of PG.

Suicide effect on rat gliomas mediated by recombinant adenovirus thymidine kinase/acyclovir system

OBJECTIVE

To establish the replicated-deficient recombinant adenovirus-mediated thymidine kinase/acyclovir (Adtk/ACV) system and to evaluate its suicide effect on rat C6 brain gliomas in vitro and in vivo.

METHODS

The plasmid pAdtk and pJM17 were co-infected into 293 cells (adenovector packaging cells) and the results were identified by polymerase chain reaction (PCR) assay. After the glioma C6 cells were transduced by Adtk at different multiplicity of infection (MOI) and exposed to different concentrations of ACV or gancyclovir (GCV), the cell survival curves were studied, and the cell surface was observed with scanning electronic microscopy (SEM). C6 gliomas in vivo at different inoculation days were injected with Adtk intratumorally and ACV intraperitoneally daily, and the survival duration and histologic changes of the rats were observed.

RESULTS

The infectious Adtk virions had a suicide effect which was enhanced with the increase in MOIs of Adtk and ACV doses along with bystander effect. Under scanning electronic microscope, special pathologic changes were observed. ACV had a similar effect as GCV but a higher dose was used. The survival duration in day 3, day 6 and day 8 groups exceeded 90 days, and the rats in day 10 group survived 28.5 +/- 4.6 days, but the survival duration in untreated C6 group and AdLacZ/ACV (adenovirus-mediated LacZ/ACV) treated group were 16.8 +/- 3.1 and 14.0 +/- 2.2 days respectively.

CONCLUSION

Adtk/ACV system can effectively kill the rat brain gliomas in vitro and in vivo.

Polymorphism of DXS102 locus in Chinese population and its application to gene diagnosis in hemophilia B family

OBJECTIVE

To establish the polymorphism of DXS102 locus from Xq26.3-27.1 in Chinese population for the gene diagnosis in Hemophilia B family.

METHODS

DNA was extracted from blood samples obtained from Shanghai unrelated volunteer donors with phenol-chloroform method. A total of 23x chromosomes (154 from females, 80 from males) were studied. A hemophilia B family in which a hemophilia B patient has received gene therapy was analyzed. The polymorphism of DXS102 locus in Chinese population was determined with amplified fragment length polymorphisms assay (Amp-FLP), denaturing polyacrylamide gel electrophoresis, silver stain detection. Short tandem repeats (STRs) linkage analysis was used to conduct gene diagnosis in hemophilia B family.

RESULTS

Eight alleles were found at DXS102 locus, of which two alleles were first reported. The repeated number of AC dinucleotide ranges from 13 to 21. And the values of the observed heterozygosity, calculated heterozygosity and polymorphism information content(PIC) were 0.87, 0.80, 0.80 respectively. It was also found that the difference of the allele frequencies of DXS102 in Chinese and European populations was significant. By using the linkage analysis of the DXS102 locus, a family with a hemophilia B patient receiving gene therapy in 1994 was analyzed and meanwhile a carrier in that family was then detected.

CONCLUSIONS

The polymorphism of DXS102 locus reveals significant difference between Chinese and European populations. DXS102 locus can be used as a promising marker for gene diagnosis in hemophilia B family.

A model for the mechanism of human topoisomerase I

The three-dimensional structure of a 70-kilodalton amino terminally truncated form of human topoisomerase I in complex with a 22-base pair duplex oligonucleotide, determined to a resolution of 2.8 angstroms, reveals all of the structural elements of the enzyme that contact DNA. The linker region that connects the central core of the enzyme to the carboxyl-terminal domain assumes a coiled-coil configuration and protrudes away from the remainder of the enzyme. The positively charged DNA-proximal surface of the linker makes only a few contacts with the DNA downstream of the cleavage site. In combination with the crystal structures of the reconstituted human topoisomerase I before and after DNA cleavage, this information suggests which amino acid residues are involved in catalyzing phosphodiester bond breakage and religation. The structures also lead to the proposal that the topoisomerization step occurs by a mechanism termed "controlled rotation."

[Determination of the polymorphism of DXS102 locus and its application in gene diagnosis]

OBJECTIVE

To determine the polymorphism of DXS102 and use it in gene diagnosis in hemophilia B.

METHODS

Amp-FLP and linkage analysis on 234 chromosomes.

RESULTS

Eight alleles were found at DXS102 locus. The number of AC dinucleotide repeats ranged from 13 to 21. And the observed heterozygosity, calculated heterozygosity and polymorphism information content(PIC) were 0.87, 0.80 and 0.80, respectively. It was noted that the difference of the allele frequencies of DXS102 in Chinese and European populations was significant. By using the linkage analysis of the DXS102 locus, a family with a hemophilia B patient receiving gene therapy in 1994 was analyzed and a carrier in that family was then detected.

CONCLUSION

The polymorphism of DXS102 locus reveals significant difference between Chinese and European populations. DXS102 locus can be used as a promising marker for gene diagnosis in hemophilia B family.

Determination and analysis of antigenic epitopes of prostate specific antigen (PSA) and human glandular kallikrein 2 (hK2) using synthetic peptides and computer modeling

Prostate specific antigen (PSA) and human glandular kallikrein 2 (hK2), produced essentially by the prostate gland, are 237-amino acid monomeric proteins, with 79% identity in primary structure. Twenty-five anti-PSA monoclonal antibodies (Mabs) were studied for binding to a large array of synthetic linear peptides selected from computer models of PSA and hK2, as well as to biotinylated peptides covering the entire PSA sequence. Sixteen of the Mabs were bound to linear peptides forming four independent binding regions (I-IV). Binding region I was localized to amino acid residues 1-13 (identical sequence for PSA and hK2), II (a and b) was localized to residues 53-64, III (a and b) was localized to residues 80-91 (= kallikrein loop), and IV was localized to residues 151-164. Mabs binding to regions I and IIa were reactive with free PSA, PSA-ACT complex, and with hK2; Mabs binding to regions IIb, IIIa, and IV were reactive with free PSA and PSA-ACT complex, but unreactive with hK2; Mabs binding to region IIIb detected free PSA only. All Mabs tested (n = 7) specific for free PSA reacted with kallikrein loop (binding region IIIb). The presence of Mabs interacting with binding region I did not inhibit the catalytic activity of PSA, whereas Mabs interacting with other binding regions inhibited the catalysis. Theoretical model structures of PSA, hK2, and the PSA-ACT complex were combined with the presented data to suggest an overall orientation of PSA with regard to ACT.

[Effect of Acorus tatarinowii Schott. on gastrointestinal myoelectric activity in rats]

The effect of Acorus tatarinowii on the gastrointestinal myoelectric activity and mechanism in rats was studied electrio-physiologically. The result indicates that Acorus tatarinowii helps inhibit the gastrointestinal myoelectric activity. This inhibitory effect is believed to take place through the blocking of cholinergic M and non-cholinergic M receptors, and has nothing to do with adrenergic alpha and beta receptors.

[The synthesis and immunosuppressive effects of steroid-peptide linkers]

Hydrocortisone was coupled with urotoxin tripeptide UTP-A, UTP-B and UTP-C respectively yielding 4 linkers. Their bioactivities such as prolongation of heterotopic transplanted cardiac tissue survival, inhibitory effects on phagocytosis of mouse peritoneal macrophages and the influence on Con A induced proliferation of spleen lymphocytes of mouse were observed. Compared with UTP-A, UTP-B, UTP-C or hydrocortisone the linkers were more potent immunosuppressants. The results suggest that the linker of steroid-peptide may simulate the permissive action.

Active site cavity of herpesvirus proteases revealed by the crystal structure of herpes simplex virus protease/inhibitor complex

Human herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) are responsible for herpes labialis (cold sores) and genital herpes, respectively. They encode a serine protease that is required for viral replication, and represent a viable target for therapeutic intervention. Here, we report the crystal structures of HSV-1 and HSV-2 proteases, the latter in the presence and absence of the covalently bound transition state analog inhibitor diisopropyl phosphate (DIP). The HSV-1 and HSV-2 protease structures show a fold that is neither like chymotrypsin nor like subtilisin, and has been seen only in the recently determined cytomegalovirus (CMV) and varicella-zoster virus (VZV) protease structures. HSV-1 and HSV-2 proteases share high sequence homology and have almost identical three-dimensional structures. However, structural differences are observed with the less homologous CMV protease, offering a structural basis for herpes virus protease ligand specificity. The bound inhibitor identifies the oxyanion hole of these enzymes and defines the active site cavity.

Immunoassays to study prevalence of antibody against GB virus C in blood donors

Immunoassays were developed to determine the seroprevalence of antibody against human GB virus C (GBV-C). The antigenic target in each assay was a 44.6-kDa glycosylated protein representing the first 315 amino acids encoded by the GBV-C E2 gene. Sera or plasma were assayed for E2 antibody using an anti-human EIA format in which antigen-coated polystyrene beads were reacted with sample, and bound antibody was detected by addition of enzyme labelled goat anti-human IgG. The presence of anti-E2 antibody was confirmed using a sandwich EIA format in which samples were reacted with antigen coated polystyrene beads, followed by addition of solution phase biotinylated antigen. Detection of antibody captured biotinylated E2 was accomplished by addition of enzyme-conjugated anti-biotin antibody. Antibody against the E2 antigen was detected in 7.4 and 7.8% of 500 sera and 500 plasma, respectively, from US volunteers donating to a Wisconsin blood center, and in approximately 10.7% of hepatitis and retrovirus marker-negative volunteer blood donors from a Missouri blood center. The rate in 1018 sera from US commercial donors at multiple US blood centers was 36.7%. These results indicated a relatively high prevalence of GBV-C exposure in US volunteer donors, and particularly in commercial donors. The clinical implication of the high exposure rate is unclear. These immunoassays are being combined with nucleic acid detection to assess prevalence of GBV-C world wide and to determine if GBV-C plays a role as an etiologic agent.

Transmembrane insertion of the colicin Ia hydrophobic hairpin

Colicin Ia is a bactericidal protein that forms voltage-dependent, ion-conducting channels, both in the inner membrane of target bacteria and in planar bilayer membranes. Its amino acid sequence is rich in charged residues, except for a hydrophobic segment of 40 residues near the carboxyl terminus. In the crystal structure of colicin Ia and related colicins, this segment forms an alpha-helical hairpin. The hydrophobic segment is thought to be involved in the initial association of the colicin with the membrane and in the formation of the channel, but various orientations of the hairpin with respect to the membrane have been proposed. To address this issue, we attached biotin to a residue at the tip of the hydrophobic hairpin, and then probed its location with the biotin-binding protein streptavidin, added to one side or the other of a planar bilayer. Streptavidin added to the same side as the colicin prevented channel opening. Prior addition of streptavidin to the opposite side protected channels from this effect, and also increased the rate of channel opening; it produced these effects even before the first opening of the channels. These results suggest a model of membrane association in which the colicin first binds with the hydrophobic hairpin parallel to the membrane; next the hairpin inserts in a transmembrane orientation; and finally the channel opens. We also used streptavidin binding to obtain a stable population of colicin molecules in the membrane, suitable for the quantitative study of voltage-dependent gating. The effective gating charge thus determined is pH-independent and relatively small, compared with previous results for wild-type colicin Ia.

Crystal structure of varicella-zoster virus protease

Varicella-zoster virus (VZV), an alpha-herpes virus, is the causative agent of chickenpox, shingles, and postherpetic neuralgia. The three-dimensional crystal structure of the serine protease from VZV has been determined at 3.0-A resolution. The VZV protease is essential for the life cycle of the virus and is a potential target for therapeutic intervention. The structure reveals an overall fold that is similar to that recently reported for the serine protease from cytomegalovirus (CMV), a herpes virus of the beta subfamily. The VZV protease structure provides further evidence to support the finding that herpes virus proteases have a fold and active site distinct from other serine proteases. The VZV protease catalytic triad consists of a serine and two histidines. The distal histidine is proposed to properly orient the proximal histidine. The identification of an alpha-helical segment in the VZV protease that was mostly disordered in the CMV protease provides a better definition of the postulated active site cavity and reveals an elastase-like S' region. Structural differences between the VZV and CMV proteases also suggest potential differences in their oligomerization states.

Induction of p21 mediated by reactive oxygen species formed during the metabolism of aziridinylbenzoquinones by HCT116 cells

Aziridinylbenzoquinones are a group of antitumor agents that elicit cytotoxicity by generating either alkylating intermediates or reactive oxygen species. The mechanism of toxicity may not always, however, involve profound damage of cellular constituents, but may involve a cytostatic effect through interference with the cell cycle. In this context, we have examined the induction of the cell cycle inhibitor p21 (WAF1, CIP1, or sdi1), whose overexpression suppresses the growth of various tumor cells, in human tumor cells metabolizing 3,6-diaziridinyl-1,4-benzoquinone (DZQ) and its C2,C5-substituted derivatives: 2,5-bis-(carboethoxyamino) (AZQ) and 2, 5-bis-2(-hydroxyethylamino) (BZQ). Both DZQ and AZQ were effectively activated by HCT116 human colonic carcinoma cells; the activation of the former involved largely a dicoumarol-sensitive activity, whereas that of the latter appeared to be accomplished primarily by one-electron transfer reductases. BZQ was not a substrate for the dicoumarol-sensitive enzyme in HCT116 cells. Cellular activation of the first two quinones was associated with formation of oxygen-centered radicals as detected by EPR in conjunction with the spin trap 5,5'-dimethyl-1-pyrroline-N-oxide. The redox transitions of DZQ involved hydroxyl radical formation and were strongly inhibited by catalase, whereas those of AZQ showed a strong superoxide anion component sensitive to superoxide dismutase. These signals were suppressed by N-acetylcysteine with concomitant production of a thiyl radical adduct. This suggests an effective electron transfer between the thiol and free radicals formed during the activation of these quinones. DZQ and AZQ induced significantly the expression of p21 in HCT116 cells, but a 10-fold higher concentration of AZQ was required to achieve the level of induction elicited by DZQ. BZQ had little effect on p21 expression. p21 induction at both mRNA and protein levels correlated with the inhibition of either cyclin-dependent kinase activity or cell proliferation. p21 induction elicited by the above quinones was inhibited by N-acetylcysteine, whereas the non-sulfur analog, N-acetylalanine, was without effect. Catalase and superoxide dismutase did not effect p21 induction by aziridinylbenzoquinones in HCT116 cells, thus suggesting that extracellular sources of oxygen radicals generated by plasma membrane reductases have no influence in the expression of this gene. Hydrogen peroxide, a product of quinone redox cycling, elicited an increase of p21 mRNA levels in HCT116 and K562 human chronic myelogenous leukemia cells. The latter lacks p53, one of the activators of p21 transcription, thus suggesting that p21 expression can be accomplished in a p53-independent manner in these cells. This study suggests that p21 induction is mediated by an increase in the cellular steady-state concentration of oxygen radicals and that the greater effectiveness in p21 induction by DZQ may be related to its efficient metabolism by NAD(P)H:quinone oxidoreductase activity in HCT116 cells.

[Determination of puerarin in gegen ginlian tablets by RP-HPLC]

A quantitative method was developed for the determination of puerarin in Gegen Qinglian Tablets by reversed phase HPLC. Chromatographic conditions included column ODS-C18, column temperature: 35 C, UV detector: 250 nm, mobile phase: EtOH-H2O (23:77), flow rate: 1 ml/min. The number of theoretical plates calculated for puerarin peak was no less than 2000. The standard curve was linear in the concentration range of 5-80 micrograms/ml, and the correlation coefficient was 0.9999. The average recovery and the relative standard deviation were 97.6% and 1.8% respectivily.

PO149, a new member of pollen pectate lyase-like gene family from alfalfa

PO149 is a low-copy-number gene expressed in the late stages of pollen development. The promoter region contains no similarities in DNA sequence to those of other pollen-specific genes, except for a tobacco sequence (AAATGA), which occurs four times in this alfalfa gene and much further upstream than in tobacco. Four distinct TATA boxes were detected in the promoter with the distal and proximal TATA boxes being separated by a spacer of 269 nucleotides. Hairpin loop structures were found in the 5'- and 3'-untranslated regions of PO149 mRNA. The coding region of PO149 is interrupted by two introns and encodes a putative prepeptide of 450 amino acids with homology to pollen pectate lyase-like proteins and pollen allergens. The coding region also contains sequences characteristic of both a signal peptide and a nuclear localization signal.

Molecular basis for lack of expression of HLA class I antigens in human small-cell lung carcinoma cell lines

HLA class I molecules present antigenic peptides to cytotoxic T lymphocytes and thus play an important role in immune surveillance of cells infected with virus or altered by malignant transformation. Immunochemical studies have demonstrated a marked deficiency or lack of expression of class I molecules on the surface of many different types of tumor cells. It is likely that this allows these cells to escape immune surveillance. In the present study, we examined the molecular basis for lack of expression of class I antigens in small-cell lung carcinoma cell lines. Our results demonstrate that these cell lines also lacked products of MHC-encoded proteasome subunit LMP2 and the putative peptide transporter TAP1. In contrast, LMP7 and TAP2 genes were expressed in these cell lines. Pulse-chase experiments showed that class I molecules were unstable and thus not transported to the cell surface from endoplasmic reticulum. Our results suggest that antigenic peptides were not available for binding to class I alpha chains due to lack of TAP1 and LMP2 gene products. Investigations of the regulatory mechanisms of TAP1 and LMP2 genes showed that the tumor cells lacked trans -regulatory nuclear protein(s), which binds to the interferon-gamma (IFN-gamma) response element (ISRE) in the TAP1, LMP2 bidirectional intergenic promoter. Treatment of tumor cells with IFN-gamma induced ISRE-binding nuclear protein(s) and resulted in expression of TAP1 and LMP2 genes with a concomitant increase in cell-surface expression of class I molecules. Our data provide credence for a role of TAP and LMP genes in immune response.

Implantation of autologous skin fibroblast genetically modified to secrete clotting factor IX partially corrects the hemorrhagic tendencies in two hemophilia B patients

OBJECTIVE

To examine the safety and effects of gene therapy for hemophilia B by implantation of autologous fibroblasts genetically modified to secrete clotting factor IX (hFIX).

PATIENTS AND METHODS

Two hemophilia B patients LD and LW were selected from one family to accept gene transfer study. The hFIX protein of both patients were about 100 ng/ml plasma and hFIX activity was about 2%. The autologous skin fibroblasts of the two patients were genetically modified by retrovirus-mediated gene transfer with XL-IX and N2CMVIX vector (HBSF-IX). Human hFIX protein was measured by ELISA, hFIX activity was measured by one-stage clotting assay and barium citrate sorbent method. hFIX inhibitor was assayed by Bethesda methods. Human hFIX cDNA was detected by PCR. HBSF-IX cells were mixed with collagen for injection after safety assessments.

RESULTS

The HBSF-IX cells from the two patients secreted hFIX at high levels in vitro. After implantation of autologous HBSF-IX cells, no treatment-related side effects were observed. Plasma hFIX protein in both patients increased over 2 folds after several injections of HBSF-IX cells and persisted for more than 420 days. Blood clotting activity increased significantly in both patients, hemorrhagic tendencies have been partially corrected after treatment. Further elevation of hFIX can be achieved by repeating the same treatment 420 days later in Patient LD.

CONCLUSIONS

Implantation of autologous fibroblast genetically modified to secrete human hFIX offers a simple, safe and effective approach to gene therapy of hemophilia B.

Y box-binding trans-regulatory nuclear proteins and susceptibility to rheumatoid arthritis

OBJECTIVE

Inappropriately high levels of expression of HLA-DR molecules or their expression on inappropriate cells, e.g. synovial tissue and T cells, may result in an aberrant tissue-destructive immune response and thus cause susceptibility to rheumatoid arthritis (RA).

METHODS

Patients and controls were typed for HLA-DR antigens by oligonucleotide typing of PCR-amplified DNA. Trans-regulatory nuclear proteins that bind to the Y box in DRB promotors were examined by the gel-mobility shift assay.

RESULTS

We found that the trans-regulatory nuclear protein (NF-Y), which binds to the Y box in DRB promoters and which plays a dominant role on the level of the expression and inducibility of DR genes, was absent in 50% of RA patients but not in healthy individuals (0%). Furthermore, we observed that all patients (100%) either lacked the NF-Y protein and/or carried the disease susceptibility DRB1 gene, which gives the highest relative risk value (RR = 46.6; p < 1.6 x 10(-6)) reported so far for susceptibility to RA.

CONCLUSION

The absence of the trans-regulatory nuclear protein that binds to the Y box with an inverted CCAAT motif in DRB promotors and the presence of the DRB1 gene with the amino acid motif QKRAA and QRRAA cause susceptibility to RA.

High-resolution structure of the diphtheria toxin repressor complexed with cobalt and manganese reveals an SH3-like third domain and suggests a possible role of phosphate as co-corepressor

The crystal structure of diphtheria toxin repressor (DtxR) in complex with the corepressor Co2+ has been determined at 2.0 A resolution and in complex with Mn2+ at 2.2 A resolution. The structure of the flexible third domain could be determined at this high resolution. It appears to contain five antiparallel strands exhibiting a fold very similar to the SH3 domain. A superposition of 46 equivalent C alpha atoms of DtxR and alpha-spectrin SH3 resulted in an rms deviation of 3.0 A. The sequence identity is only 7%. This third domain of DtxR appears to have no interactions with the DNA binding domain nor with the metal binding domain of the repressor. Yet, flexibility in the region between the second and the third domain allows in principle significant conformational changes such as might occur upon DNA binding. The two metal binding sites in the second domain have been unraveled in considerable detail. Metal binding site 1 was well occupied in both the cobalt and manganese structures and showed a surprising sulfate ion as ligand. The sulfate was proven beyond doubt by the high peak at its position in a selenate versus sulfate difference Fourier. The presence of the intriguing sulfate ion at such a crucial position near the metal corepressor suggests the possibility that under physiological conditions phosphate may act as a "co-corepressor" for this class of metal-regulated DNA binding proteins in Corynebacteria, Mycobacteria, and related organisms. The second metal binding site is significantly different in these two DtxR structures. In the 2.0 A cobalt structure, the site is not occupied by a metal ion. In the 2.2 A manganese structure the site is well occupied, at approximately the same position as observed previously in cadmium DtxR. The ligands are Glu105, His106, the carbonyl oxygen of Cys102, and a water molecule. The reasons for differential occupancy of this site in different structures are intriguing and require further investigations.

Unique fold and active site in cytomegalovirus protease

Human herpesviruses are responsible for a variety of diseases. They are divided into three subfamilies: alpha includes herpes simplex viruses (HSV-1 and HSV-2) and varicella-zoster virus (VZV); beta includes cytomegalovirus (CMV) and human herpesvirus-6 (HHV-6); and gamma includes Epstein-Barr virus (EBV). Each virus encodes a serine protease that is essential for its replication and is a potential target for therapeutic intervention. Human CMV is a ubiquitous opportunistic pathogen that can result in life-threatening infections in congenitally infected infants, immunocompromised individuals and immunosuppressed cancer or transplant patients. Here we report the crystal structure of human CMV protease at 2.5 angstroms resolution. The structure reveals a fold that has not been reported for any other serine protease, and an active site consisting of a novel catalytic triad in which the third member is a histidine instead of an aspartic acid, or possibly a catalytic tetrad consisting of a serine, two histidines and an aspartic acid. An unusual dimer interface that is important to the protease activity has also been identified.