Comparison of isoflurane effects on motor evoked potential and F wave

BACKGROUND

Volatile anesthetics produce surgical immobility by suppressing the motor system. The anesthetic action site in the motor pathway is unclear. Anesthetic effects on the whole and the lower portion of motor pathway can be studied by measuring the motor evoked potentials (MEP) and the F wave. This study measured the effect of isoflurane on the MEP and the F wave.

METHODS

With institutional review board approval, we studied 12 adult patients with American Society of Anesthesiologists physical status I or II. After intubation, anesthesia was maintained with nitrous oxide/oxygen and propofol infusion. MEPs were elicited by transcranial electrical stimuli (train-of-five pulse; stimuli intensity 40-160 mA) through electrodes placed in the scalp at C3/C4 positions and recorded at the anterior tibialis muscle with an Axon Sentinel-4EP monitor. F waves were elicited by an electrode fixed over the posterior tibial nerve at the medial malleolus and recorded at the abductor hallucis muscle. After end-tidal concentration of isoflurane was maintained at 0.5% for 20 min, the MEP and F wave were measured again. MEP and F-wave changes before and after isoflurane were analyzed using paired Wilcoxon test with Bonferroni correction. The difference between the changes in MEP and F wave was analyzed using Friedman's test.

RESULTS

Motor evoked potential amplitudes (median, 205 microV; 25th-75th percentiles, 120-338 microV), F-wave amplitude (median, 100 microV; 25th-75th percentiles, 64.2-137.5 microV), and F-wave persistence (59 +/- 29%) were decreased to 0 microV (0-15 microV), 49 microV (12.4-99.6 microV), and 30 +/- 31%, respectively, by 0.5% isoflurane. MEP amplitude suppression was different from the changes in F-wave amplitude and persistence (P < 0.02).

CONCLUSIONS

Isoflurane 0.5% suppresses the motor pathway by decreasing both MEP and F wave. The MEP is suppressed more than the F wave.

Identification of the functional domain in the transcription factor RTEF-1 that mediates alpha 1-adrenergic signaling in hypertrophied cardiac myocytes

Cardiac myocytes respond to alpha(1)-adrenergic receptor stimulation by a progressive hypertrophy accompanied by the activation of many fetal genes, including skeletal muscle alpha-actin. The skeletal muscle alpha-actin gene is activated by signaling through an MCAT element, the binding site of the transcription enhancer factor-1 (TEF-1) family of transcription factors. Previously, we showed that overexpression of the TEF-1-related factor (RTEF-1) increased the alpha(1)-adrenergic response of the skeletal muscle alpha-actin promoter, whereas TEF-1 overexpression did not. Here, we identified the functional domains and specific sequences in RTEF-1 that mediate the alpha(1)-adrenergic response. Chimeric TEF-1 and RTEF-1 expression constructs localized the region responsible for the alpha(1)-adrenergic response to the carboxyl-terminal domain of RTEF-1. Site-directed mutagenesis was used to inactivate eight serine residues of RTEF-1, not present in TEF-1, that are putative targets of alpha(1)-adrenergic-dependent kinases. Mutation of a single serine residue, Ser-322, reduced the alpha(1)-adrenergic activation of RTEF-1 by 70% without affecting protein stability, suggesting that phosphorylation at this serine residue accounts for most of the alpha(1)-adrenergic response. Thus, these results demonstrate that RTEF-1 is a direct target of alpha(1)-adrenergic signaling in hypertrophied cardiac myocytes.

Differential incorporation of 1-beta-D-arabinofuranosylcytosine and 9-beta-D-arabinofuranosylguanine into nuclear and mitochondrial DNA

The anti-leukemic nucleoside analogs 1-beta-D-arabinofuranosylcytosine (araC) and 9-beta-D-arabinofuranosylguanine (araG) are dependent on intracellular phosphorylation for pharmacological activity. AraC is efficiently phosphorylated by deoxycytidine kinase (dCK). Although araG is phosphorylated by dCK in vitro, it is a preferred substrate of mitochondrial deoxyguanosine kinase. We have used autoradiography to show that araC was incorporated into nuclear DNA in Molt-4 and CEM T-lymphoblastoid cells as well as in Chinese hamster ovary cells. In contrast, araG was predominantly incorporated into mitochondrial DNA in the investigated cell lines, without detectable incorporation into nuclear DNA. These data suggest that the molecular targets of araG and araC may differ.

DNA ligase IV deficiency in mice leads to defective neurogenesis and embryonic lethality via the p53 pathway

DNA ligase IV (LIG4) is a nonhomologous end-joining (NHEJ) protein used for V(D)J recombination and DNA repair. In mice, Lig4 deficiency causes embryonic lethality, massive neuronal apoptosis, arrested lymphogenesis, and various cellular defects. Herein, we assess potential roles in this phenotype for INK4a/ARF and p53, two proteins implicated in apoptosis and senescence. INK4a/ARF deficiency rescued proliferation/senescence defects of Lig4-deficient fibroblasts but not other phenotypic aspects. In contrast, p53 deficiency rescued embryonic lethality, neuronal apoptosis, and fibroblast proliferation/senescence defects but not lymphocyte development or radiosensitivity. Young Lig4/p53 double null mice routinely died from pro-B lymphomas. Thus, in the context of Lig4 deficiency, embryonic lethality and neuronal apoptosis likely result from a p53-dependent response to unrepaired DNA damage, and neuronal apoptosis and lymphocyte developmental defects can be mechanistically dissociated.

[Detection of core promoter mutations in chronic hepatitis B]

OBJECTIVE

To study the core promoter mutation in chronic hepatitis B and its effect on viral serology.

METHODS

HBV core promoter gene fragments were amplified by using mismatched PCR combined with a restriction fragment length polymorphism assay. The PCR products were digested with Bcl I and subjected to electrophoresis on agarose gels.

RESULTS

We investigated the core promoter mutation in 89 patients with HBV DNA positive. The patterns of restriction fragment length polymorphism (RFIP) of the core promoter gene were distinguished and verified by direct sequencing. The combined mutations of nucleotides (nt) 1762 and 1764 in the core promoter from A to T and G to A were detected in 47 individuals, 21 of 43 HBeAg positive patients and 26 of 46 anti- HBe positive cases were found infected with this combined mutant. These two groups showed no significant difference (P > 0.05). The combined mutation was found in 11 of the 15 patients with medium and severe chronic hepatitis. In 5 chronic hepatitis B patients with coexistence of wild-type and mutant a tendency of superior accumulation of mutant was found.

CONCLUSIONS

This study suggests that the core promoter mutations commonly exist in Chinese chronic hepatitis B patients. The mutation can only reduce the pre-core mRNA transcribing efficiency, but cannot discontinue the synthesis of HBeAg. The effect on serology in this mutation is different from that in pre-core stop 28 mutation. The superior accumulation of mutations seems relating to the degree of chronic liver disease.

A homolog of mammalian antizyme is present in fission yeast Schizosaccharomyces pombe but not detected in budding yeast Saccharomyces cerevisiae

MOTIVATION

The antizymes (AZ) are proteins that regulate cellular polyamine pools in metazoa. To search for remote homologs in single-celled eukaryotes, we used computer software based on hidden Markov models. The most divergent homolog detected was that of the fission yeast Schizosaccharomyces pombe. Sequence identities between S.POMBE: AZ and known AZs are as low as 18-22% in the most conserved C-terminal regions. The authenticity of the S.POMBE: AZ is validated by the presence of a conserved nucleotide sequence that, in metazoa, promotes a +1 programmed ribosomal frameshift required for AZ expression. However, no homolog was detected in the completed genome of the budding yeast Saccharomyces cerevisiae. Procedural details and supplementary information can be found at http://itsa.ucsf.edu/ approximately czhu/AZ.

The membrane anchor influences ligand binding two-dimensional kinetic rates and three-dimensional affinity of FcgammaRIII (CD16)

Kinetic rates and affinity are essential determinants for biological processes that involve receptor-ligand binding. By using a micropipette method, we measured the kinetics of human Fcgamma receptor III (CD16) interacting with IgG when the two molecules were bound to apposing cellular membranes. CD16 is one of only four eukaryotic receptors known to exist natively in both the transmembrane (TM, CD16a) and glycosylphosphatidylinositol (GPI, CD16b) isoforms. The biological significance of this anchor isoform coexistence is not clear. Here we showed that the anchor influenced kinetic rates; compared with CD16a-TM, CD16a-GPI bound faster and with higher affinities to human and rabbit IgGs but slower and with lower affinity to murine IgG2a. The same differential affinity patterns were observed using soluble IgG ligands. A monoclonal antibody bound CD16a-GPI with higher affinity than CD16a-TM, whereas another monoclonal antibody reacted strongly with CD16a-TM but weakly with CD16a-GPI. No major differential glycosylation between the two CD16a isoforms was detected by SDS-polyacrylamide gel electrophoresis analysis. We suggest a conformational difference as the mechanism underlying the observed anchor effect, as it cannot be explained by the differing diffusivity, flexibility, orientation, height, distribution, or clustering of the two molecules on the cell membrane. These data demonstrate that a covalent modification of an Ig superfamily receptor at the carboxyl terminus of the ectodomain can have an impact on ligand binding kinetics.

3Beta-hydroxy-6-aza-cholestane and related analogues as phosphatidylinositol specific phospholipase C (PI-PLC) inhibitors with antitumor activity

6-Aza steroid analogues were synthesized as PI-PLC inhibitors. The most active compound, 3beta-hydroxy-6-aza-cholestane (1) showed potent PI-PLC inhibition (IC50 = 1.8 microM), similar to that of the commercially available steroid analogue U73122 (IC50 = 1-2.1 microM). Compound 1 exhibited significant growth inhibition effects (IC50 = 1.3 microM in each case) against MCF-7 and HT-29 cancer cells in in vitro cell culture. Compound 1 also inhibited the in vitro adhesion and transmigration of HT-1080 fibrosarcoma cells at 2.5 and 5.0 microM, respectively. In vivo, compound 1, at 1 mg/kg/day, reduced the volume of MCF-7 tumors in xenograft models, without weight loss in mice. Structure activity relationships of this series of compounds revealed that a hydrophobic cholesteryl side chain, 3beta-hydroxy group and a C-6 nitrogen containing a hydrogen atom at position-6 are crucial for activity. N-Maleic amidoacid derivative 11 also exhibited weak inhibition (IC50 = 16.2 microM).

Expression and regulation of mRNAs for insulin-like growth factor-I receptor and LH receptor in corpora lutea

Relationship between insulin-like growth factor-I receptor (IGF-IR) and luteinizing hormone receptor (LHR) mRNA expression as well as their regulation was determined in rat corpora lutea (CL). In the CL of estrous cycle rat, LHR mRNA positive CL expressed high level of mRNA of IGF-IR. While the expression of LHR mRNA decreased on estrus, the CL still expressed relatively high level of IGF-IR mRNA. In pseudopregnant rat CL, the expression level of LHR mRNA was low on day 1, the most intense signals were detected on day 8, the signals of LHR mRNA became undetectable on day 14. In contrast to LHR expression, the high level of IGF-IR mRNA was observed in pseudopregnant CL of day 1, and thereafter its signals were detected from day 2 to day 14. Pregnant rat CL expressed both LHR and IGF-IR mRNAs. IGF-I stimulated LHR expression in CL. PGF(2alpha) inhibited expression of IGF-IR and LHR. PGE(2) negated the inhibiting effects of PGF(2alpha). These data suggest that IGF-I may be involved in regulating CL function, and maintaining CL structure through changes in expression of its receptors. Inhibited expression of IGF-IR by PGF(2alpha) may be part of mechanisms for regression of CL.

Cell-specific, activation-dependent regulation of neutrophil CD32A ligand-binding function

Neutrophils express 2 low-affinity FcgammaR, FcgammaRIIIB (CD16B), and FcgammaRIIA (CD32A). CD16B is a glycosyl-phosphatidyl inositol-anchored molecule, whereas CD32A is a polypeptide-anchored molecule. These 2 receptors also differ in their signaling. The biological significance of coexpression of 2 FcgammaRs with distinct membrane anchors and signaling capacities is not clearly understood. Using neutrophils from a CD16B-deficient donor and normal neutrophils treated with anti-CD16 monoclonal antibodies, the authors demonstrated that affinity modulation of CD32A is one of the mechanisms by which neutrophils regulate their FcgammaR-dependent functions. Neutrophils isolated from a CD16B(- )donor rosetted poorly with sheep erythrocytes opsonized with rabbit IgG (EA) (12% +/- 2% versus 80% +/- 6% for control) and were unable to mediate immunophagocytosis. However, activation of CD16B(-) neutrophils with fMLP, a bacterial chemotactic peptide, increased the CD32A-dependent EA rosetting to 58%. The CD32A-dependent rosetting of fMLP-activated normal neutrophils also increased nearly 5-fold, but there was no increase in CD32A expression. The CD32A-dependent immune complex (IC) binding was also increased in activated neutrophils. This affinity regulation was not observed with CD32A expressed on Chinese hamster ovary cells. These results suggest that in resting neutrophils CD32A is in a low-affinity state and that these cells primarily engage CD16B for IC binding. However, once the neutrophils are activated, the CD32A is converted to a high-affinity state that leads to CD32A-dependent ligand binding and signaling. These results suggest that neutrophils adopt a novel strategy to engage the 2 different FcgammaR selectively during physiologic and pathologic conditions to carry out their functions efficiently.

Kinetics and mechanics of cell adhesion

Cell adhesion is mediated by specific interaction between receptors and ligands. Such interaction provides not only physical linkage but also communication between the cell and its environment. The kinetics and mechanics of cell adhesion are coupled, because force can influence the formation and dissociation of receptor-ligand bonds. The kinetic rates and their force dependence determine how likely, how rapidly and how strongly cells bind as well as how long they remain bound. Since adhesion molecules are linked to apposing cellular membranes, their interaction is governed by two-dimensional (2D) kinetics. This is in contrast to the three-dimensional (3D) binding of soluble ligands to cell surface receptors. Unlike the 3D case in which many methods are available for measuring kinetic rates, not until recently have the 2D kinetic rates become experimentally measurable. In this review, I will discuss the recent progress in the experimental methods that enable quantification of the relevant kinetic and mechanical parameters, the fundamental concepts that underlie the physics of the biological phenomena, and the mathematical models that relate functions to the intrinsic properties of the adhesion molecules.

Screening of novel epilepsy-related genes and isolation and identification of cDNAs

Twenty cDNA differential fragments were isolated from the hippocampus of rats in epileptic state using mRNA differential display technique. Four fragments were sequenced and compared with the known sequences in the Genebank, which showed that ERG8, ERG11, ERG12 had no significant identity to any known sequences; ERG14 had 64%-69% identity to microtubulin-associated protein of the rat. Because the differential expression of these genes was caused by epilepsy inducer coriaria lactone (CL) and anti-epilepsy drug MK-801 and ERG8 might be a novel candidate epilepsy gene; ERG11 and ERG12 might be novel candidate anti-epilepsy genes. Since the microtubulin-associated protein is closely associated with the collateral sprouting of mossy fibers in the hippocampus of seizured rat, the high expression of ERG14 in the early stage of epilepsy might predict the growth of axon and formation of synapse.

Effect of coriaria lactone on membrane potential of hippocampal neurons in rats

Intracellular recording method of electrophysiology was used to study the effect of microinjection of coriaria lactone (CL) into hippocampus on membrane potential of hippocampal neurons in rats. The membrane potential in 34 neurons of 12 rats were recorded. The results showed that CL induced depolarization of all of 34 neurons examined. Among the 34 neurons, 15 had paroxysmal depolarization accompanied by spike discharge in cluster and spike discharge in cluster ceased when membrane was hyperpolarized, 7 showed continuous depolarization accompanied by continuous spike discharge and 12 had only depolarizing response. The results suggest that injection of CL into hippocampus may lead to an increase of excitability of local neurons accompanied by different patterns of epileptioform discharge.

Double labeling immunoelectron microscopic study on the synaptic connections between glutamic acid neurons and GABA neurons in the hippocampus of rats

In order to explore the roles of different neurotransmitters in epileptic pathogenesis, the synaptic connections between glutamic acid (Glu) neurons and GABA neurons in normal rat hippocampus were studied by pre-embedding double labeling immunoelectron microscopy. The GABA immunoreaction was first demonstrated by chromogen DAB, then the Glu immunoreaction was demonstrated by molybdic acid-TMB method. After being stabilized by DAB-cobalt chloride, the sections were processed for electron microscopic embedding. Under electron microscope, there were many Glu immunoreaction-positive neurons in the pyramidal layer of hippocampal CA1 area and some GABA immunoreaction-positive neurons with pyramidal or polygonal perikarya in the pyramidal, polymorphic and radiant layer of CA1 area. There were also symmetric dendro-axonic synapses formed by GABA-positive dendrites and Glu-positive axons in the polymorphic layer and symmetric axo-dendrites synapses formed by GABA-positive axons and Glu-positive dendritic in the radiant layer. In addition, there were symmetric autoregulatory axo-dendritic synapses between Glu-positive axons and dendrites and autoregulatory axo-axonic synapses (both symmetric and asymmetric) between GABA-positive axons. Above mentioned results, for the first time, showed that there were complex synaptic regulatory relationships between excitatory Glu neurons and inhibitory GABA neurons in the hippocampal CA1 area, thereby, providing ultrastructural evidence for different neurotransmitters participating in epileptic pathogenesis.

The effect of coriaria lactone on NMDA receptor mediated currents in rat hippocampal CA1 neurons

To investigate the exact mechanism of epileptogenesis induced by coriaria lactone (CL), the effect of CL on NMDA receptor mediated current (IAsp) in rat hippocampal CA1 neurons was investigated by using nystatin perforated whole-cell patch clamp. 10(-6)-10(-4) mol/L Asp acted on NMDA receptors and elicited an inward current (IAsp) at a holding potential (VH) of -40 mV in presence of 10(-6) mol/L glycine and absence of Mg2+ extracellularly. CL enhanced NMDA receptor mediated current induced by Asp, but had no effect on threshold concentration, EC50, Hill coefficient as well as maximal-effect concentration and reversal potential of IAsp. The effect had no relationship with holding potential. These results showed that CL could enhance NMDA receptor mediated current to increase [Ca2+]i of neurons by acting on Gly site, thereby inducing epilepsy.

Quantification of porcine follicle-stimulating hormone receptor messenger ribonucleic acid by reverse transcription-competitive polymerase chain reaction

An easy and reliable method was developed for construction and quantification of competitive templates, which shared the same sequence as the amplified target DNA except for a 20-bp insertion in the middle by recombinant polymerase chain reaction (PCR). Among the advantages of competitive PCR is that any predictable or unpredictable variable that affects amplification has the same effect on both target and competitor species and that the final ratio of amplified products reflects exactly the initial targets. The utilization of a thermostable reverse transcriptase in the RT step was proposed to overcome the problem of the efficiency of target cDNA synthesis. In addition, to obtain reliable measurements, it was recommended to perform four PCR with amounts of competitive template flanking the concentration of the target mRNA.

[Study on expression of disaccharide residue and its significance in lung cancer tissues.]

BACKGROUND

To study the expression of disaccharide residu (D-Galactose-beta-(1v3)-N-Acetyl- galactosamine) in lung cancer.

METHODS

Surgical dissected samples from 109 cases of lung cancer and 87 cases of lung benign diseases were fixed in 4 % formaldehyde and embeded in parafin. Disaccharide residue was examined by galactose oxidase-Schiff's method.

RESULTS

The positive rate of bronchial submucous glands from patients with lung cancer was 71. 76 %(61/ 85) , and the positive rate of bronchial submucous gland from patients with benign pulmonary diseases was 71. 83 %(51/ 71) . There was no significant difference between two groups (Chi-Square = 0. 0026 , P > 0. 9) . Among 94 cases of lung cancer tissues , the positive rate of adenocarcinoma was 36. 11 %(13/ 36) , and the other lung cancer were negative reaction.

CONCLUSIONS

The study showed that disaccharide residue was expressed in submucous glands of bronchial submuca in both patients with pulmonary benign or malignant diseases , and only expressed in partial adenocarcinoma tissues among the pulmonary carcinoma. It has not enough evidence to differentiate benign from malignant diseases of lung.

Analysis of competition binding between soluble and membrane-bound ligands for cell surface receptors

Binding of the Fc portion of IgG coated on targets to Fcgamma receptors (e.g., CD16) expressed on leukocytes (i.e., 2D binding) is an initiating step for immune responses such as phagocytosis or antibody-dependent cellular cytotoxicity. In vivo, circulating leukocytes are exposed to plasma IgG. The competition from soluble IgG (i.e., 3D binding) may affect the 2D binding. Many cell surface receptors, CD16 included, have soluble counterparts. While their physiological significance is not clear, receptor-based competitive inhibition therapy, in which soluble receptors, ligands, and their analogs are employed to compete with surface-bound receptors and ligands to prevent unwanted adhesion, is widely used to treat various diseases. To provide a quantitative basis for design of these therapeutic approaches, we developed a mathematical model for 2D and 3D competition binding. The model relates cell-surface adhesion (in the presence and absence of dislodging forces) to the concentration of the soluble competitor, the densities of the surface-bound receptors and ligands, as well as the binding affinities of the 2D and 3D interactions. Binding of CD16-expressing cells to an IgG-coated surface in the presence of a soluble competitor (IgG or anti-CD16 antibody) was quantified by a centrifugation assay. The agreement between experiment and theory supports the validity of the model, which could be useful in predicting the efficacy of the competitor.

[Identification study on pig's hoofnail]

The identification characteristics of pig's hoofnail on properties and tissue slice was initially probed from the viewpoint of identification in this paper in order to make basis for the systematic research on replacing Squama manitis.

[Transposition of Tn5096 in a agricultural antibiotic 120 roducer Streptomyces hygrospinocus var. beijingensis RF220]

No transformant was obtained when pCZA168(bla, tsr, Tn5096, ColEI rep. Strep repts) was used to transform S. hygropinocus RF220. pIJ702 isolated from S. hygroscopicus N103 was transformed into RF220 at a low frequency. pIJ702 plasmid was cured in RF220 transformant and it was re-transformed into its cured FR220 strain, but the transformation frequency was not increased significantly, suggesting that restriction-modification system in FR220 was existent and complicated. Four transformants containing pCZA168 were obtained, when the RF220 strain was grown in medium with ampicillin, glycine and the protoplast was stored at -70 degrees C. Restriction analysis of plasmid from transformants indicated that the DNA fragment from E. coli in pCZA168 was deleted. With transposition of Tn5096, two mutants blocked in antibiotic biosynthesis of 120 and some mutants with variation in antibiotic level were obtained, this showed that the Tn5096 transposed in different positions of chromosomal DNA in RF220 and resulted in the production of 120 in different level.

Intra-arterial blood pressure reference ranges, death and morbidity in very low birthweight infants during the first seven days of life

OBJECTIVES

We aimed to: (1) assess the association of average, low, high and variable mean blood pressure (mbp) on death and the common morbidities of very low birthweight infants, and in doing so, (2) to derive representative reference ranges for mbp in very low birthweight infants.

STUDY DESIGN

This five year retrospective study assessed 1 min computer recordings of intra-arterial mbp in 232 very low birthweight infants over the first 7 days of life in a tertiary NICU. Four measures of mbp were assessed: average, variability, maximum (per time period), and percentage of time with a mean blood pressure less than the infant's gestation. Correlation was made with death and the development of intraventricular haemorrhage (IVH), periventricular leukomalacia (PVL) and retinopathy of prematurity (ROP).

RESULTS

The mbp increased with increasing birthweight and postnatal age (though with a slight decrease on days 6 and 7). Birthweight, gestation and colloid support (adjusted for birthweight and gestation) were the only factors significantly associated with mbp. IVH was predominantly associated with a low and variable mbp on the day IVH was noted or the day before. PVL and ROP were not associated with blood pressure.

CONCLUSIONS

These reference ranges include more infants and data than previously published and relate mbp in this cohort to morbidity and mortality. They could assist clinicians in judging appropriate mbp for birthweight.

[Expression of glycoprotein hepatitis C virus in mammalian cell and application of purified protein for detection of antibody against E2 in hepatitis C patients]

OBJECTIVE

E2 glycoprotein of hepatitis C virus was expressed in mammalian cell and purified for detection of antibody against E2 in hepatitis C patients.

METHODS

E2/NS1 gene derived from HCV was inserted into expression vector containing six His tag. The recombinant plasmid was transfected into mammalian cells to express E2 glycoprotein expression. E2 glycoprotein was purified by affinity chromophotography. The purified protein was used to establish EIA method for detection of antibodies against E2 in hepatitis C patients.

RESULT

Expressed E2 glycoprotein was 7.0 x 10(4). Purification of the purified E2 protein was 90.2%. Twenty-nine patients were anti-E2 antibody positive(82.9%).

CONCLUSION

It was the first time to establish EIA method for detection of anti-E2 antibody by purified E2 glycoprotein in China. E2 glycoprotein expressed in mammalian cells had good immunogenity and could increase the sensibility of anti-HCV detection. It suggests that E2 glycoprotein may be useful for development of new anti-HCV reagents.

[Analysis of genome character and amino acid residues 2,209 to 2,248 of NS5 A region of hepatitis C virus in relation to the response to interferon therapy]

OBJECTIVE

To observe nucleotide sequence variations and amino acid residues 2,209 to 2,248 of the NS5 A region of hepatitis C virus in relation to interferon therapy in Chinese patients infected with HCV genotype 1b.

METHODS

We collected sera from 22 patients infected with HCV genotype 1b, performed nested RT-PCR using extracted serum RNA from sera, amplified NS5 A region 2,209 to 2,248 and sequenced the PCR product directly. The deduced amino acid sequences were compared with the corresponding region of the HCV-J prototype strain.

RESULTS

Only 4 isolates were intermediate type, and no mutant type was found. In 18 patients treated with IFN-alpha, only 4 were HCV RNA negative at present, No correlation was found between amino acid mutation and IFN response.

CONCLUSION

Variations in the NS5 A region between amino acid residues 2,209 to 2,248 failed to predict IFN response in Chinese patients infected with HCV genotype 1b. IFN may accelerate nucleotide variation but has little influence on amino acid variations.

Tyrosine replacement in P-selectin glycoprotein ligand-1 affects distinct kinetic and mechanical properties of bonds with P- and L-selectin

Selectins are adhesion molecules that initiate tethering and rolling of leukocytes on the vessel wall. Rolling requires rapid formation and breakage of selectin-ligand bonds that must have mechanical strength to resist premature dissociation by the forces applied in shear flow. P- and L-selectin bind to the N-terminal region of P-selectin glycoprotein ligand-1 (PSGL-1), a mucin on leukocytes. To define determinants on PSGL-1 that contribute to the kinetic and mechanical properties of bonds with selectins, we compared rolling of transfected preB cells expressing P- or L-selectin on transfected cell monolayers expressing wild-type PSGL-1 or PSGL-1 constructs with substitutions in targeted N-terminal residues. Rolling through P- or L-selectin required a Thr or Ser at a specific position on PSGL-1, the attachment site for an essential O-glycan, but required only one of three nearby Tyr residues, which are sites for Tyr-SO(3) formation. The adhesive strengths and numbers of cells rolling through P- or L-selectin were similar on wild-type PSGL-1 and on each of the three PSGL-1 constructs containing only a single Tyr. However, the cells rolled more irregularly on the single-Tyr forms of PSGL-1. Analysis of the lifetimes of transient tethers on limiting densities of PSGL-1 revealed that L-selectin dissociated faster from single-Tyr than wild-type PSGL-1 at all shears examined. In sharp contrast, P-selectin dissociated faster from single-Tyr than wild-type PSGL-1 at higher shear but not at lower shear. Thus, tyrosine replacements in PSGL-1 affect distinct kinetic and mechanical properties of bonds with P- and L-selectin.

Cloning of mouse mitochondrial thymidine kinase 2 cDNA

Phosphorylation of anti-viral nucleoside analogs by mitochondrial thymidine kinase 2 (TK2) has been implicated as a mechanism for the mitochondrial toxicity caused by several of these compounds. We have cloned the cDNA of mouse TK2 and shown that the enzyme is targeted to the mitochondria when expressed in fusion with the green fluorescent protein. This is the first report on the cloning of a mitochondrial TK2 and will contribute to elucidate the role of TK2 in the pharmacological activation of nucleoside analogs.