Amino acid substitutions within the leucine zipper domain of the murine coronavirus spike protein cause defects in oligomerization and the ability to induce cell-to-cell fusion

The murine coronavirus spike (S) protein contains a leucine zipper domain which is highly conserved among coronaviruses. To assess the role of this leucine zipper domain in S-induced cell-to-cell fusion, the six heptadic leucine and isoleucine residues were replaced with alanine by site-directed mutagenesis. The mutant S proteins were analyzed for cell-to-cell membrane fusion activity as well as for progress through the glycoprotein maturation process, including intracellular glycosylation, oligomerization, and cell surface expression. Single-alanine-substitution mutations had minimal, if any, effects on S-induced cell-to-cell fusion. Significant reduction in fusion activity was observed, however, when two of the four middle heptadic leucine or isoleucine residues were replaced with alanine. Double alanine substitutions that involved either of the two end heptadic leucine residues did not significantly affect fusion. All double-substitution mutant S proteins displayed levels of endoglycosidase H resistance and cell surface expression similar to those of the wild-type S. However, fusion-defective double-alanine-substitution mutants exhibited defects in S oligomerization. These results indicate that the leucine zipper domain plays a role in S-induced cell-to-cell fusion and that the ability of S to induce fusion may be dependent on the oligomeric structure of S.

AP180 and AP-2 interact directly in a complex that cooperatively assembles clathrin

Clathrin-coated vesicles are involved in protein and lipid trafficking between intracellular compartments in eukaryotic cells. AP-2 and AP180 are the resident coat proteins of clathrin-coated vesicles in nerve terminals, and interactions between these proteins could be important in vesicle dynamics. AP180 and AP-2 each assemble clathrin efficiently under acidic conditions, but neither protein will assemble clathrin efficiently at physiological pH. We find that there is a direct, clathrin-independent interaction between AP180 and AP-2 and that the AP180-AP-2 complex is more efficient at assembling clathrin under physiological conditions than is either protein alone. AP180 is phosphorylated in vivo, and in crude vesicle extracts its phosphorylation is enhanced by stimulation of casein kinase II, which is known to be present in coated vesicles. We find that recombinant AP180 is a substrate for casein kinase II in vitro and that its phosphorylation weakens both the binding of AP-2 by AP180 and the cooperative clathrin assembly activity of these proteins. We have localized the binding site for AP-2 to amino acids 623-680 of AP180. The AP180/AP-2 interaction can be disrupted by a recombinant AP180 fragment containing the AP-2 binding site, and this fragment also disrupts the cooperative clathrin assembly activity of the AP180-AP-2 complex. These results indicate that AP180 and AP-2 interact directly to form a complex that assembles clathrin more efficiently than either protein alone. Phosphorylation of AP180, by modulating the affinity of AP180 for AP-2, may contribute to the regulation of clathrin assembly in vivo.

[Enhancing effect of Chinese herbal medicine mixture on peripheral blood lymphocyte proliferation and interleukin-2 production in patients of burn]

OBJECTIVE

To study the regulatory effect of Chinese herbal medicine mixture (CHMM) on cell-mediated immune function in patients of burn.

METHODS

Patients of burn were treated with CHMM and the therapeutic effect was evaluated by their peripheral blood T-lymphocyte (PBL) proliferation and interleukin-2 (IL-2) production determination.

RESULTS

The PBL proliferation began to increase after 5 days of medication and the response was significant between the 10th to 20th day, which was in accordance with the change of IL-2 production.

CONCLUSION

CHMM has immune regulatory effect on cell-mediated immune function in patients of burn.

[The design of a reflection sensor of NIRS tissue oximetry]

A design of the reflection light-electric Sensor suited to monitoring the statues of tissue blood oxygen on the surface of body is described. The designed sensors have been used too to detect blood oxygen statues of brain and muscle respectively, and many useful informations have been acquired Therefore The above-mentioned design is reasonalle and Feasikle.

Adenovirus-mediated delivery of the Gax transcription factor to rat carotid arteries inhibits smooth muscle proliferation and induces apoptosis

Adenovirus-mediated gene delivery in animal models of vascular injury has provided insights into the mechanisms underlying vessel wall pathologies. We have previously demonstrated that overexpression of the Gax transcription factor inhibits neointimal formation in rat and rabbit models of arterial injury. Here, we evaluate potential mechanisms for the reduction in stenotic lesion size due to Gax overexpression. At 3, 7 and 14 days after injury the Ad-Gax-infected arteries displayed a marked decrease in medial vascular smooth muscle cell number (3 days, 54% reduction P < 0.01; 7 days, 41% reduction P < 0.003; 14 days, 49% reduction P < 0.02). At 3 days after injury, PCNA expression was attenuated in the Ad-Gax-treated vessels compared with control vessels (65% reduction P < 0.02), indicating a reduction in cellular proliferation. At 7 days and 14 days after injury Ad-Gax-infected arteries exhibited elevated number of TUNEL-positive medial VSMCs compared with control-treated arteries (7 days, 9.2-fold increase P < 0.03; 14 days, 17.2-fold increase P < 0.03), indicating an induction of apoptotic cell death. These data suggest that deregulated Gax expression induces first cell cycle arrest and then apoptosis in the vascular smooth muscle cells that contribute to the neointimal layer. Therefore, the efficacy of this therapeutic strategy appears to result from the ability of the Gax transcriptional regulator to modulate multiple cellular responses.

Adenovirus-mediated delivery of fas ligand inhibits intimal hyperplasia after balloon injury in immunologically primed animals

BACKGROUND

Adenoviral constructs have been used for studies of injury-induced vascular hyperplasia in immunologically naive laboratory animals, but their usefulness for intra-arterial gene therapy may be limited by the prevalence of preexisting immunity to adenovirus in the patient population. Here, we explored the efficacy of adenovirus-mediated transfer of Fas ligand, a cytotoxic gene with immunomodulatory properties, in inhibiting injury-induced vascular lesion formation in both naive and immunologically primed animals.

METHODS AND RESULTS

Lesion formation was evaluated in balloon-injured carotid arteries of naive and adenovirus-immunized rats that were infected with adenoviral constructs expressing Fas ligand (Ad-FasL), the cyclin-dependent kinase inhibitor p21 (Ad-p21), or beta-galactosidase (Ad-betagal). In naive rats, Ad-FasL induced apoptosis in medial vascular smooth muscle cells and inhibited intimal hyperplasia by 60% relative to Ad-betagal-treated vessels (P<0.05), whereas the cytostatic agent Ad-p21 decreased lesion size by 58% (P<0.05). In animals preimmunized with an adenoviral vector containing no transgene, Ad-FasL significantly inhibited neointima formation (73% reduction, P<0.05), but Ad-p21 failed to inhibit neointima formation relative to controls. Immunologically primed rats displayed robust T-cell infiltration in Ad-p21- and Ad-betagal-treated vessels, but T-cell infiltration was markedly attenuated in Ad-FasL-treated vessels.

CONCLUSIONS

Our data demonstrate that adenovirus-mediated Fas ligand delivery can inhibit intimal hyperplasia in both immunologically primed and naive animals, whereas the efficacy of an adenovirus-mediated p21 delivery is limited to immunologically naive animals. This study documents, for the first time, the therapeutic efficacy of intravascular adenoviral gene transfer in animals with preexisting immunity to adenovirus.

Viral myocarditis: identification of five differentially expressed genes in coxsackievirus B3-infected mouse heart

Differences in host susceptibility to viral myocarditis caused by a given strain of coxsackievirus B3 (CVB3) are known to be largely related to host genetic factors. Little is known, however, about the key genes that encode determinants (mediators) of myocarditis development or the nature of injury. To identify these genes and further understand the molecular mechanisms of the disease process, we have used a murine model and the differential display technique to fingerprint mRNAs from CVB3-infected mouse hearts. Total RNA was extracted from hearts of 4- and 10-week-old A/J(H-2(a)) mice at day 4 after CVB3 infection, and mRNAs were detected by reverse transcriptase-polymerase chain reaction and subsequently analyzed on polyacrylamide DNA sequencing gels. The differentially displayed bands were confirmed by Northern hybridization using the bands as cDNA probes. Twenty-eight upregulated or downregulated bands were selected from the sequencing gels; among these, 2 upregulated and 3 downregulated cDNA fragments were confirmed by Northern hybridization. DNA sequence analysis and GenBank searching have determined that 4 of the 5 candidate genes are homologous to genes encoding Mus musculus inducible GTPase, mouse mitochondrial hydrophobic peptide (a subunit of NADH dehydrogenase), mouse beta-globin, and Homo sapiens cAMP-regulated response element binding protein (CREB) binding protein (CBP), respectively. The remaining candidate gene matches an unpublished cDNA clone, M musculus Nip21 mRNA (GenBank accession number, AF035207), which is homologous to human Nip2, a Bcl-2 binding protein. Our data suggest preliminarily that both structural and nonstructural genes are involved in myocarditis development. For the structural gene, beta-globin, we further confirmed its downregulation at the protein level by measuring the mean cell volume of red blood cells and found it was marginally reduced in the CVB3-infected group (P<0.06), with no change in hemoglobin concentration. Cardiac myoglobin concentration was also measured and found to be decreased (P<0.005), with a parallel decrease in total soluble protein in the CVB3-infected mouse myocardium (P<0.01). We also noted that the ratio of myoglobin to total protein was not significantly changed; this may be due to the downregulation of additional genes in the host heart, a number being observed on the differential display gels. The significant downregulation of beta-globin major gene expression in the heart may be relevant to impaired cardiac function in both the early and late postinfection period. The other identified nonstructural genes are known to be involved in regulation of gene expression, signal transduction pathways, and apoptotic cell death. The altered expression of structural and nonstructural genes may play important roles in the mediation of myocarditis development and perhaps other pathological processes in the heart.

Reversal of GATA-6 downregulation promotes smooth muscle differentiation and inhibits intimal hyperplasia in balloon-injured rat carotid artery

The GATA-6 transcription factor is expressed in quiescent vascular smooth muscle cells (VSMCs) in culture, and levels of its transcript are rapidly downregulated on mitogen stimulation. In this study, we demonstrate that the GATA-6 transcript, protein, and DNA-binding activity are downregulated in rat carotid arteries on balloon injury. Downregulation was detected at 1 and 3 days after injury and recovered by 7 days. To assess the role of GATA-6 downregulation in injury-induced vascular lesion formation, adenoviral vectors were used to express wild-type human GATA-6 cDNA (Ad-GATA6) or an inactive mutant cDNA that lacks a portion of the zinc-finger domain (Ad-GATA6DeltaZF). Adenovirus-mediated GATA-6 gene transfer to the vessel wall after balloon injury partially restored the levels of GATA-6 protein and DNA-binding activity to before injury levels. The local delivery of Ad-GATA6 but not Ad-GATA6DeltaZF inhibited lesion formation by 46% relative to saline control and 50% relative to a control adenovirus that expressed lacZ. Local delivery of Ad-GATA6 also reversed changes in the expression patterns of smooth muscle myosin heavy chain, smooth muscle alpha-actin, calponin, vinculin, metavinculin, and proliferating cell nuclear antigen that are associated with injury-induced VSMC phenotypic modulation. These data indicate that the injury-induced downregulation of GATA-6 is an essential feature of VSMC phenotypic modulation that contributes to vessel lesion formation.

A Chinese triconodont mammal and mosaic evolution of the mammalian skeleton

Here we describe a new triconodont mammal from the Late Jurassic/Early Cretaceous period of Liaoning, China. This new mammal is represented by the best-preserved skeleton known so far for triconodonts which form one of the earliest Mesozoic mammalian groups with high diversity. The postcranial skeleton of this new triconodont shows a mosaic of characters, including a primitive pelvic girdle and hindlimb but a very derived pectoral girdle that is closely comparable to those of derived therians. Given the basal position of this taxon in mammalian phylogeny, its derived pectoral girdle indicates that homoplasies (similarities resulting from independent evolution among unrelated lineages) are as common in the postcranial skeleton as they are in the skull and dentition in the evolution of Mesozoic mammals. Limb structures of the new triconodont indicate that it was probably a ground-dwelling animal.

Early cell loss after angioplasty results in a disproportionate decrease in percutaneous gene transfer to the vessel wall

Acute cell loss has been documented following angioplasty of normal rat and rabbit arteries. Here we analyzed the effects of balloon injury intensity on early cellular loss in single- and double-injury models and how it influences the efficiency of percutaneous gene delivery to the vessel wall. Rabbits underwent bilateral iliac angioplasties (n = 52) with 2.5-mm (balloon-to-artery [B/A] ratio, 1.08 to 1.13) and 3.0-mm (B/A ratio, 1.29 to 1.34) balloons. In the single-injury model, the 3.0-mm balloon induced a 61% reduction in medial cellularity at 3 days postinjury (p < 0.001) while the 2.5-mm balloon did not produce significant cell loss. In the double-injury model, the effects were more pronounced, with 35% (p < 0.01) and 91% (p < 0.001) reductions in medial cellularity at 3 days with the 2.5- and 3.0-mm balloons, respectively, but neointimal cellularity was decreased only with the 3.0-mm balloon (37% reduction, p = 0.025). Adenovirus-mediated beta-galactosidase gene delivery with a channel balloon (n = 24) revealed that larger balloon-to-artery ratios decreased both absolute levels and relative frequencies of transgene expression in the vessel wall. In the single-injury model, gene transfer efficiency was 4.2+/-1.1 and 1.3+/-0.25% (p < 0.05) for the small and large balloons, respectively. In the double-injury model, gene transfer efficiency was 6.6+/-1.6 and 2.3+/-0.8% (p < 0.05) in the neointima and 4.1+/-1.2 and 2.6+/-1.2% (p = NS) in the media for the small and large balloon, respectively. We conclude that early cell loss is dependent on the intensity of the injury in both single- and double-injury models of balloon angioplasty, with greater frequencies of cell loss occurring in the media than in the neointima. In both models, larger balloon-to-artery ratios result in disproportionate reductions in percutaneous adenovirus-mediated gene delivery.

Hyperglycemia inhibits insulin activation of Akt/protein kinase B but not phosphatidylinositol 3-kinase in rat skeletal muscle

Sustained hyperglycemia impairs insulin-stimulated glucose utilization in the skeletal muscle of both humans and experimental animals--a phenomenon referred to clinically as glucose toxicity. To study how this occurs, a model was developed in which hyperglycemia produces insulin resistance in vitro. Rat extensor digitorum longus muscles were preincubated for 4 h in Krebs-Henseleit solution containing glucose or glucose + insulin at various concentrations, after which insulin action was studied. Preincubation with 25 mmol/l glucose + insulin (10 mU/ml) led to a 70% decrease in the ability of insulin (10 mU/ml) to stimulate glucose incorporation into glycogen and a 30% decrease in 2-deoxyglucose (2-DG) uptake, compared with muscles incubated with 0 mmol/l glucose. Glucose incorporation into lipid and its oxidation to CO2 were marginally diminished, if at all. The alterations of glycogen synthesis and 2-DG uptake were first evident after 1 h and were maximal after 2 h of preincubation; they were not observed in muscles preincubated with 25 mmol/l glucose + insulin for 5 min. Preincubation for 4 h with 25 mmol/l glucose in the absence of insulin produced a similar although somewhat smaller decrease in insulin-stimulated glycogen synthesis; however, it did not alter 2-DG uptake, glucose oxidation to CO2, or incorporation into lipids. Studies of insulin signaling in the latter muscles revealed that activation of Akt/protein kinase B (PKB) was diminished by 60%, compared with that of muscles preincubated in a glucose-free medium; whereas activation of phosphatidylinositol (PI) 3-kinase, an upstream regulator of Akt/PKB in the insulin-signaling cascade, and of mitogen-activated protein (MAP) kinase, a parallel signal, was unaffected. Immunoblots demonstrated that this was not due to a change in Akt/PKB abundance. The results indicate that hyperglycemia-induced insulin resistance can be studied in rat skeletal muscle in vitro. They suggest that impairment of insulin action in these muscles is related to inhibition of Akt/PKB by events that do not affect PI 3-kinase.

Skeletal muscle regulatory proteins enhance F-actin in vitro motility

Using an in vitro motility assay, we have investigated the effects of rabbit skeletal muscle regulatory proteins, troponin and tropomyosin, on the gliding of F-actin filaments or F-actin filaments containing these regulatory proteins. We demonstrate that Ca2+ does not affect the motility of F-actin gliding on HMM, but does in the presence of skeletal muscle tropomyosin and troponin. We conclude that Ca2+ affects motility through troponin because, like F-actin, F-actin-Tm filaments show no Ca(2+)-dependence to their gliding speeds. Furthermore, there is a large enhancement of the gliding speed (about 75%) in the presence of skeletal muscle tropomyosin, troponin + saturating Ca2+ over that seen with F-actin filaments. This enhancement is not due to the action of tropomyosin alone as skeletal muscle tropomyosin without troponin enhances the speed little (about 5%) over that of F-actin. Thus troponin confers Ca2+ sensitivity to the motility and, additionally, potentiates motility greatly along with tropomyosin in the presence of saturating Ca2+. When [HMM] is varied, the decline in speed of F-actin seen at low HMM density is changed little by tropomyosin in the F-actin-Tm filaments. These data show that the skeletal regulatory proteins interact with F-actin to enhance the interaction with HMM particularly in the presence of troponin and saturating Ca2+ and enhance the gliding speed in the in vitro motility assay as they potentiate the ATPase activity in the isolated proteins. This enhancement of speed in the motility assay cannot be ascribed to tropomyosin alone.

[The protective role of heat shock gene expression on hydrogen peroxide induced pulmonary alveolar macrophages]

The aim of this study is to determine whether heat-induced heat shock gene expression in rat pulmonary alveolar macrophages (PAMs) would protect PAMs against hydrogen peroxide (H2O2)-mediated cell killing. In response to sublethal heat shock at 42 degrees C for 2 h, the cells synthesized heat shock protein 70 kD (HSP70) and other different molecular weight heat shock proteins, which were detected with gel electrophoresis after [35S]-methionin labeling cellular protein and Western blotting analysis in PAMs. Northern blot analysis showed the induction of HSP70 mRNA with heat shock treatment. Futhermore, with heat shock, there was a significant increment of survival cells after H2O2 (1,2,3 mmol.L-1, 45 min) exposure. This increase was blocked both by Cycloheximide and by Actinomycin D, and was associated with inhibition of synthesis of HSP70 protein and transcription of HSP70 mRNA. These results strongly suggest that expression of heat shock gene (especially HSP70 gene) plays an important role in the intracelluar mechanism of cytoprotection against H2O2 in rat PAMs.

[The effects of deferoxamine on bovine pulmonary endothelial cell injury induced by hydrogen peroxide]

The effect of deferoxamine (DFX), the ferric iron chelator, on bovine pulmonary endothelial cell (BPAEC) injury induced by hydrogen peroxide (H2O2) was examined in vitro. It was found that, when compared with unpretreated cells, H2O2-induced the release of lactate dehydrogenase and the production of thiobarbituric acid reactive substances were decreased, at the meantime the cellular activites of catalase and superoxide dismutase were maintained in DFX (2 mmol.L-1) pretreated BPAECs challenged by 1 mmol.L-1 H2O2. These data indicate that DFX provided almost complete protection against H2O2-mediated cytotoxicity. This suggests that intracellular iron may play an essential role in the endothelial cell injury mediated by H2O2.

[The expression of CD11a and CD11b on leucocytes in cerebral thrombosis]

This study sought to understand the mechanism for the increased adhesion of leucocytes and endothelial cells in ischemic stroke. 20 patients with acute cerebral thrombosis and 20 healthy subjects as controls for expression of CD11a and CD11b (adhesion molecules on surface of leucocytes) were tested in vitro by flow cytometry (FCM) method. The results showed that compared with the control group, the patient group had significantly higher rates for expression of CD11a on monocytes, granulocytes and lymphocytes (P < 0.05). The CD11b expression in the patient group was positively elevated on monocytes and granulocytes (P < 0.05), but it was of lower positive rate on lymphocytes and no statistical difference was noted between the patient and control groups. These indicate that the expression of CD11a and CD11b on leucocytes increases in cerebral ischemic damage; thus adhesion of leucocytes and endothelial cells obviously increases. This change may aggravate post-ischemic delayed neuronal death.

[The surgical treatment of tetralogy of fallot in 136 adults]

OBJECTIVE

To summarize the experience of surgical treatment of tetralogy of Fallot (TOF) in adults.

METHOD

From April 1975 to December 1997, 136 adult patients underwent total corrective repair of tetralogy of Fallot. The patient age ranged from 14 to 52 years old. The ventricular septal defects were closed with Dacron patch in 112 patients, with pericardial patch in 24 patients. A right ventricular outflow patch was required to eliminate right ventricular outflow tract obstruction in 126 patients.

RESULT

Five patients died during hospitalization, with a hospital mortality of 3.68%. Four early postoperative deaths were due to severe low cardiac output syndrome.

CONCLUSION

In view of current improved and standardized techniques, we conclude that the total corrective repair of TOF may have an excellent result in adult patients.

Diffusion-based learning theory for organizing visuo-motor coordination

A diffusion-based learning theory is presented and applied to organize the visuomotor coordination of an eye-hand system which has redundant motion degree of freedom (dof). This theory considers the spatial optimality of the coordination: to minimize the end-effector position error of the eye-hand system as well as the differentiation of the joint angles with respect to the end-effector positions over all the bounded work space. By introducing variational methods with respect to the space, we derive a partial differential equation (PDE) of the joint angles with respect to the work space. The equation includes a diffusion term. For the given boundary conditions and the initial conditions, it can be solved uniquely, and the solution is a well organized map. From the motor learning point of view, our approach contains both the aspects of supervised learning as well as self-organization. Firstly, we assume that the forward relation from the hand system's joint angles to its end-effector positions can be obtained using supervised learning, and at the boundary of the work space, the supervisor can provide correct joint information. Then, by evolving the diffusion equation, we organize the visuomotor coordination. We show the effectiveness of this approach using a 3-dof scale manipulator. The problems of how to realize the visuomotor map; how to utilize the resultant map in several motions; and what are the influences of the initial conditions on the map formation and the relation to the boundary conditions are also discussed using computer simulations. Our approach has three advantages: (1) it does not require too many trial motions for the eye-hand system; (2) during the map formation process, it requires only the local interactions between each node; and (3) it guarantees the final map's spatial optimality over all the bounded work space.

Electron dose calculation using multiple-scattering theory: a hybrid electron pencil-beam model

We have embedded the bipartition model into Fermi-Eyges multiple-scattering theory to produce a more accurate hybrid electron pencil-beam model, by using the fact that away from the edges of a large field, the electron distribution function exactly equals that for an infinitely wide electron beam. The bipartition model calculates various electron transport quantities in a homogeneous or horizontally layered medium with very high accuracy, for an infinitely broad beam. In our hybrid model, we use the bipartition model to calculate the longitudinal part of the pencil-beam distribution function, and the Fermi-Eyges theory to calculate its transverse part. Doing this allows calculation not only of dose distribution, but also of such quantities as electron fluence distribution, energy spectrum, angular distribution, and electron-charge distribution. Using the hybrid electron pencil-beam model, we have calculated the dose distribution for collimated electron beams and compared them with experimental data, for rectangular fields.

"Propylene spaced" allyl tin reagents: a new class of fluorous tin reagents for allylations under radical and metal-catalyzed conditions

A new generation of propylene-spaced fluorous allyltin reagents [(Rf(CH2)3)3SnCH2CH = CH2] is described. These succeed in radical allylations where their lower homologs (ethylene-spaced) fail, and they provide improved performance in transition metal catalyzed allylations. The reagents and byproducts are readily separated by simple fluorous-organic liquid-liquid or solid-liquid extractions.

Alpha2-adrenergic agonists selectively activate extracellular signal-regulated kinases in Müller cells in vivo

PURPOSE

Alpha2-adrenergic agonists have specific and selective effects on the retina to induce expression of basic fibroblast growth factor and to protect photoreceptors. This work explores the signaling pathway that mediates these effects.

METHODS

Alpha2-adrenergic agonists xylazine and clonidine were administered systemically to male adult Sprague-Dawley rats. The activation state of extracellular signal-regulated kinases (ERKs) in the retina was assessed by immunoblot analysis, using antibodies that specifically recognize the dually phosphorylated forms of p44/p42 ERKs. Localization of phosphorylated ERKs was determined by immunocytochemistry.

RESULTS

Intramuscular injection of 6 mg/kg xylazine induced an increase in ERK phosphorylation in the retina within 30 minutes that lasted 3 hours. Xylazine induced ERK phosphorylation at 1 mg/kg and reached a maximum at 10 mg/kg. Injection of clonidine also induced ERK phosphorylation in the retina. Yohimbine, a specific alpha2-adrenergic antagonist, completely prevented the induction of ERK phosphorylation. Immunocytochemical studies showed that the increase in ERK phosphorylation occurred mainly in Müller cells. In the brain, xylazine injection resulted in a decrease in ERK phosphorylation.

CONCLUSIONS

Our results indicate that systemically administered alpha2-adrenergic agonists selectively activate ERKs in retinal Müller cells. The induced activation of ERKs in Müller cells is probably one of the early events that result in photoreceptor protection. These results also indicate that Müller cells are unique in response to alpha2-adrenergic agonists and imply a role for Müller cells in alpha2-adrenergic agonist-induced photoreceptor protection.

[Detection of HGV NS5 antigen in liver tissue of patients with chronic liver disease]

OBJECTIVE

To investigate the existence of hepatitis G virus (HGV) in liver tissue.

METHODS

HGV NS5 antigen was detected by immunohistochemical method in paraffin-embeded liver tissue of autopsy patients with chronic liver disease.

RESULTS

Among 110 samples, 32.7% (36/110) had been detected out HGAg in their liver. When serologica marker was used, the detection rate was 21% (4/19) in HNA-E, 36% (25/69) in HBV and 32% (7/22) in HCV infectious group, respectively. HGAg expression in hepatocytes was also found pathologically in 22% of 45 patients with active cirrhosis, 43% of 47 patients with hepatocellular carcinoma, and 33% of 18 patients with chronic fulminent hepatitis. The staining signal of HGV NS5 antigen was mainly located in the cytoplasm of liver or neoplasm cells, and the positive cells were distributed diffusely in pseudolobule or liver tissues.

CONCLUSION

The infection of viral G is often seen in liver tissue of patients with chronic liver disease.

The gene 4 of rice yellow stunt rhabdovirus encodes the matrix protein

The complete nucleotide sequence of the gene 4 of rice yellow stunt rhabdovirus (RYSV) was determined from cDNAs corresponding to the viral genomic RNA. Gene 4 is 913 nucleotides (nt) long, comprising a 17-nt untranslated 5' region, a 786-nt open reading frame encoding a polypeptide with a molecular mass of 29,125 Da, and a 110-nt untranslated 3' region. Western blot analysis of the RYSV proteins using the antiserum raised against the protein expressed from the cloned gene in Escherichia coli indicates that gene 4 encodes the M protein of RYSV. Comparisons of the deduced amino acid sequence of the M protein of RYSV with those of other rhabdoviruses revealed no significant homologies. However, it shared a similar basic property and a similar distribution of charges with the other rhabdovirus matrix proteins and showed a relatively closer relationship to the sonchus yellow net virus (SYNV) M1 protein.

A dimeric 14-3-3 protein is an essential cofactor for Raf kinase activity

cRaf-1 is a mitogen-activated protein kinase that is the main effector recruited by GTP-bound Ras in order to activate the MAP kinase pathway. Inactive Raf is found in the cytosol in a complex with Hsp90, Hsp50 (Cdc37) and the 14-3-3 proteins. GTP-bound Ras binds Raf and is necessary but not sufficient for the stable activation of Raf that occurs in response to serum, epidermal growth factor, platelet-derived growth factor or insulin. These agents cause a two- to threefold increase in overall phosphorylation of Raf on serine/threonine residues, and treatment of cRaf-1 with protein (serine/threonine) phosphatases can deactivate it, at least partially. The role of 14-3-3 proteins in the regulation of Raf's kinase activity is uncertain and is investigated here. Active Raf can be almost completely deactivated in vitro by displacement of 14-3-3 using synthetic phosphopeptides. Deactivation can be substantially reversed by addition of purified recombinant bacterial 14-3-3; however, Raf must have been previously activated in vivo to be reactivated by 14-3-3 in vitro. The ability of 14-3-3 to support Raf activity is dependent on phosphorylation of serine residues on Raf and on the integrity of the 14-3-3 dimer; mutant monomeric forms of 14-3-3, although able to bind Raf in vivo, do not enable Raf to be activated in vivo or restore Raf activity after displacement of 14-3-3 in vitro. The 14-3-3 protein is not required to induce dimerization of Raf. We propose that dimeric 14-3-3 is needed both to maintain Raf in an inactive state in the absence of GTP-bound Ras and to stabilize an active conformation of Raf produced during activation in vivo.

Glycophorin variants and contents of sialic acid and total sulfhydryl groups on erythrocyte membranes of residents in a malaria hyperendemic area

OBJECTIVE

To conduct a screening survey of glycophorin (GP) variants and observe the content changes of sialic acid (SA) and total sulfhydryl (SH) groups on the erythrocyte membranes among residents in a tertian malaria hyperendemic area of Guizhou Province.

METHODS

GP variants were detected in the erythrocyte hemolysates of 173 local residents at two villages of Libo County by SDS-PAGE on 10% to 15% gradients gel and Western immunoblotting. Their SA and total SH group contents were estimated in erythrocyte membranes by spectrophotometric methods. 114 healthy subjects in Changsha and 49 individuals at a neighbouring village of the above area showing low morbidity of malaria served as normal and endemic controls respectively.

RESULTS

Three distinct types of GP variants were found among 19 propositi in this hyperendemic area. The incidence of GP variants was 7.9% (8/101) at Yaolu Village whose population was mainly composed of Yao ethnic group; while that of Buyi ethnic group at Maolan Village was higher (15.3%; 11/72). The erythrocyte membrane contents of SA in residents at both villages exhibited a very significant tendency of decline (P < 0.01), whereas those of total SH groups increased prominently in residents of Yaolu Village only (P < 0.05).

CONCLUSIONS

The frequency of GP variants in this hyperendemic area does not depend upon the severity of malarial prevalence. The evident reduction of SA contents in the residents may be related to the breaking down of the SA residues on membrane GPs by the invasion of Plasmodium vivax.

[The effects of Chinese medicine herb mixture on cell-mediated immune functions and four kinds of acute-phase reaction proteins in burn patients]

OBJECTIVE

To search for immunomodulators to improve postburn immune function disorder.

METHOD

We studied the Chinese medicinal herbs. On the basis of previous data, we prepared a kind of Chinese medicinal herbal mixture and studied its effects in vivo and in vitro.

RESULT

The mixture could restore the cell-mediated immune response such as the production of interleukin 2 and the T cell proliferative ability, and could also adjust the levels of serum acute-phase reaction proteins, i.e, haptoglobin, prealbumin, transferrin and alpha 1-acid glycoprotein.

CONCLUSION

The Chinese herbal mixture showed immune regulatory effects on body defence imbalance and also on acute phase reaction proteins in burn patients.

Roles in cell-to-cell fusion of two conserved hydrophobic regions in the murine coronavirus spike protein

The spike (S) protein of coronavirus mouse hepatitis virus (MHV), mediates attachment and fusion during viral entry and cell-to-cell fusion later in infection. By analogy with other viral proteins that induce cell fusion the MHV S protein would be expected to have a hydrophobic stretch of amino acids that serves as a fusion peptide. Sequence analysis suggests that the S protein falls within the group of fusion proteins having internal rather than N-terminal fusion peptides. Based on the features of known viral fusion peptides, we identified two regions (PEP1 and PEP2) of MHV-A59 S2 as possible fusion peptides. Site-directed mutagenesis and an in viro cell-to-cell fusion assay were used to evaluate the roles of PEP1 and PEP2, as well as a third previously identified putative fusion domain (PEP3) in membrane fusion. Substitution of bulky hydrophobic residues with charged residues within PEP1 affects the fusion activity of the S protein without affecting processing and surface expression. Similar substitutions within PEP2 result in a fusion-negative phenotype; however, these mutant S proteins also exhibit defects in protein processing and surface expression which likely explain the loss of the ability to induce fusion. Thus PEP1 remains a candidate fusion peptide, while PEP2 may play a significant role in the overall structure or oligomerization of the S protein. PEP3 is an unlikely putative fusion peptide since it is not conserved among coronaviruses and nonconservative amino acid substitutions in PEP3 have minimal effects on cell-to-cell fusion.

Generation of constitutively active recombinant caspases-3 and -6 by rearrangement of their subunits

Caspases play a major role in the transduction of the apoptotic signal and execution of apoptosis in mammalian cells. Ectopic overexpression of the short prodomain caspases-3 and -6 precursors in mammalian cells does not induce apoptosis. This is due to their inability to undergo autocatalytic processing/activation and suggests that they depend on the long prodomain caspases for activation. To investigate directly the apoptotic activity of these two caspases in vivo, we engineered constitutively active recombinant caspases-3 and -6 precursors. This was achieved by making contiguous precursor caspases-3 and -6 molecules, which have their small subunits preceding their large subunits. Unlike their wild type counterparts, these recombinant molecules were capable of autocatalytic processing in an in vitro translation reaction, suggesting that they are catalytically active. They were also capable of autoprocessing and inducing apoptosis in vivo independent of the upstream caspases. Furthermore, their autocatalytic and apoptotic activities were inhibited by the pancaspase inhibitor z-VAD-fluoromethylketone, but not by CrmA or Bcl-2, thus directly demonstrating that the targets of inhibition of apoptosis by CrmA and Bcl-2 are upstream of caspases-3 and -6. Since caspases-3 and -6 are the most downstream executioners of apoptosis, the constitutively active versions of these caspases could be used at very low concentrations in gene therapy model systems to induce apoptosis in target tissues or tumors.

Structural studies of synthetic peptide fragments derived from the HIV-1 Vpr protein

Vpr, one of the accessory gene products of the human immunodeficiency virus-1 (HIV-1) genome, exhibits diverse biological characteristics. Vpr functions as a transcriptional activator of HIV and heterologous promoters. It is capable of arresting cells in cell cycle progression and plays a crucial role in the infection of macrophages. Despite the wealth of information available on the biological aspects of Vpr, the structure of Vpr remains poorly understood. To gain insight into the structure-function relationship of Vpr, peptides corresponding to putative helical regions of Vpr were synthesized and their structures determined by circular dichroism (CD) spectroscopy. The CD studies confirmed the predicted helical structures of these peptides. Based on the data, a hypothetical model for the structure of Vpr was proposed which displays an anti-parallel alpha-helix core structure reminiscent of a helix-loop-helix motif. These findings are consistent with the results from mutational studies of Vpr and provide a plausible structural basis to further investigate the multiple functions of Vpr as a viral protein.

[Study on telomeric association in nasopharyngeal carcinoma]

The chromosomal telomeric association in peripheral blood lymphocytes from 25 untreated patients with nasopharyngeal carcinoma (NPC) and in NPC cell lines (CNE) was investigated by using chromosome G banding technique. The cell telomeric association rate of patients (35.07%) was found to be higher than that of controls(20.27%) (P < 0.01), while in the two groups the distributions of chromosomes involved were approximately the same (P > 0.05). The telomeric association rates of patients were significantly higher than those of control in chromosomes 1, 2, 3, 4, 7, 11, 15, and 17(P < 0.05). In NPC lines (CNE), 94% of the cell division phases showed telomeric association. Chromosomes 2, 3, 5, 11 and 16 had higher frequencies of association than other chromosomes. The most frequent telomeric association was single chromatid association.

[Modulated effects of prostaglandin E2 on endothelin production of alveolar macrophages in rats]

Using radioimmunoassay, we studied the endothelin (ET) production of alveolar macrophages(AM) of the rats. The results showed that: (1) a basal amount of ET which was time-dependent (r = 0.7415, P < 0.01) was detected in supernatant of cultured unstimulated AM; (2) lipopolysaccharide (LPS), PMA, or A23187 could increase the ET production of AM (P < 0.01) (3) calmodulin antagonist W7 reduced the ET production of LPS or A23187-stimulated AM (P < 0.05, P < 0.01), but did not effect that of PMA-stimulated AM; protein kinase C inhibitor H7 attenuated the effect of PMA on ET production (P < 0.01), but did not effect LPS on ET production; (4) prostaglandin E2 (PGE2) inhibited the ET production of LPS-stimulated (P < 0.05) and PMA-stimulated AM (P < 0.05); cyclooxygenase inhibitor indomethacin enhanced the effect of LPS on ET production (P < 0.01), but did not effect PMA on ET production. We conclude that AM is an important source of ET in the lungs both at physiologic and pathologic situation there are two pathways of signal transduction for factors stimulating ET production of AM, i.e., PKC-dependent and Ca(2+)-calmodulin-dependent pathways; the autocrine PGEs from AM shows a negatively modulated effect on ET production of AM.

Reduction of vein graft intimal hyperplasia and preservation of endothelium-dependent relaxation by topical vascular endothelial growth factor

PURPOSE

Recent evidence suggests that vascular endothelial growth factor (VEGF), in addition to stimulating angiogenesis, also serves a repair/maintenance or survival function, modulating various aspects of endothelial cell function. This study was designed to examine the effect of VEGF pretreatment in a model of vein graft intimal hyperplasia.

METHODS

Reversed jugular vein-to-common carotid artery interposition grafts were constructed in New Zealand White rabbits. White rabbits. Vein conduits were immersed in solution containing 500 micrograms rhVEGF165 or saline solution for 20 minutes before implantation. Twenty-eight days later the vein grafts and contralateral control jugular veins were harvested for either histologic or isometric tension studies.

RESULTS

VEGF-treated vein grafts showed a 23% reduction in intimal area (0.76 +/- 0.07 mm2 vs 0.98 +/- 0.06 mm2; p = 0.028) and a 30% reduction in intimal thickness (62 +/- 6 microns vs 89 +/- 5 microns; p = 0.001) when compared with control grafts. After precontraction with norepinephrine, the maximal relaxation to acetylcholine (endothelium-dependent, receptor-mediated agonist) for control vein grafts was 0%, whereas for VEGF-treated vein grafts it was 25% +/- 9% (p < 0.05 vs control grafts). The maximal relaxation to the calcium ionophore A23187 (endothelium-dependent, receptor-independent agonist) was also greater in VEGF-treated grafts than in control grafts (172.3% +/- 19.4% vs 122.5% +/- 13.7%; p < 0.05). There was no difference in the response to sodium nitroprusside (endothelium-independent agonist) between the two groups.

CONCLUSIONS

A single topical application of VEGF before implantation reduces intimal hyperplasia and improves endothelial function in a rabbit vein graft model. Further evaluation of this simple strategy to improve vein graft patency appears warranted.

Characterization of troponin-C interactions in skinned barnacle muscle: comparison with troponin-C from rabbit striated muscle

Previously it was shown that when troponin-C (TnC) is extracted from barnacle myofibrillar bundles they lose their Ca2+ sensitivity, which can be restored by adding back barnacle TnC (either isoform, BTnC1 or BTnC2). Thus barnacle muscle shows thin filament regulation, as does rabbit psoas skeletal muscle. In this paper we compare the interactions of barnacle and rabbit fast muscle TnC in their respective muscles. We demonstrate that muscle fibres from the giant barnacle, Balanus nubilus, contain about 186 microM kg-1 muscle tissue of BTnC1 plus BTnC2 compared to about 91 microM kg-1 of TnC in rabbit psoas muscle fibres. Extraction of BTnC is achieved using similar low ionic strength, low divalent ion Ca(2+)-low Mg2+ conditions which are required for TnC extraction in rabbit psoas skinned muscle fibres; extraction was prevented by 1 mM Mg2+. Full reconstitution of Ca(2+)-sensitivity was achieved by adding back BTnC (1 + 2, or 2). Reconstitution of barnacle muscle with rabbit fast skeletal TnC (RTnC) was more complex, with partial recovery of Ca(2+)-sensitivity with reconstitution in the presence of 3 mM Mg2+ and more fully with reconstitution in the presence of activating Ca2+ (pCa 4.0). This suggests that the barnacle TnC-TnI (troponin I) recognition sites may be more complex than in rabbit because the barnacle sites appear to have at least two different conformations or types, in which one recognizes RTnC in the presence of Mg2+ and the other only in the presence of Ca2+ and Mg2+. This is consistent with the presence of several TnI isoforms in barnacle striated myofibrils. RTnC has two C-terminal Ca(2+)-Mg2+ binding sites that are thought to be involved in the Mg(2+)-sensitive binding of RTnC in rabbit muscle, yet it has been suggested that this site in barnacle muscle does not bind Mg2+, even though Mg2+ stabilizes BTnC binding in barnacle muscle. Consistent with this stabilizing action of Mg2+, using fluorescent probes IAANS or IAE on isolated BTnC2 we demonstrate that BTnC2 binds both Ca2+ and Mg2+, but the data do not suggest direct competition. Consistent with the C-terminal sites on BTnC being Ca(2+)-specific, BTnC1 + 2 could only reconstitute low levels of force (about 1/3) in TnC-extracted rabbit skinned muscle fibers in the presence of pCa 4.0 (not just Mg2+) and only at low ionic strengths (0.09 M). Ca(2+)-activation of contraction was further examined using fluorescently labelled BTnC2 (labelled with IANBD) incorporated into skinned barnacle myofibrillar bundles. Maximal Ca2+ binding produced structural changes in BTnC which resulted in a 45% decrease in the fluorescence compared to the value at pCa 9.2. The magnitude of the fluorescence decrease paralleled the increase in force with increasing Ca2+. The Hill fits to the data gave pCa1/2 and n of 5.61 +/- 0.02 and 2.06 +/- 0.12 for force, and 5.52 +/- 0.02 and 1.88 +/- 0.10 for fluorescence. Removing MgATP to induce rigor in the fibre decreased BTnC2-NBD fluorescence only about 11%, but the addition of Ca2+ in rigor further decreased the fluorescence to a slightly larger extent than under maximal Ca2+ activating conditions. These fluorescence changes are qualitatively similar to the fluorescence enhancement seen with Ca(2+)-activation and rigor with RTnCDanz exchanged into rabbit psoas skinned muscle fibres. The data support a similar model for Ca(2+)-activation of force in barnacle muscle and in rabbit psoas skeletal muscle fibres.

[The immune response in rats immunized systemically by the surface protein antigen P1 from streptococcus mutans conjugated with procholeragenoid]

This study was carried out to observe the antibody responses in rats after they were immunized with the surface protein P1 of streptococcus mutans when a special adjuvant was used. Antigen P1 was conjugated covalently with procholeragenoid (PCG), and then Sprague Dawley rats were immunized with P1 or the conjugated antigen P1-PCG subcutaneously or intragastrically. Anti-P1 antibody level was assayed at different time points by ELISA. The results showed that the levels of anti-P1 SIgA antibody in saliva rose when P1-PCG was given subcutaneously or intragastrically; the antibody level following the subcutaneous injection was higher and lasted longer, compared with that following the intragastric administretion. The level of anti-P1 IgG antibody in serum only rose when the rats were immunized subcutaneously. These results implied that mucosal immune response or humoral immune response could be induced subcutaneously when PCG was used as an adjuvant.

A new symmetrodont mammal from China and its implications for mammalian evolution

A new symmetrodont mammal has been discovered in the Mesozoic era (Late Jurassic or Early Cretaceous period) of Liaoning Province, China. Archaic therian mammals, including symmetrodonts, are extinct relatives of the living marsupial and placental therians. However, these archaic therians have been mostly documented by fragmentary fossils. This newfossil taxon, represented by a nearly complete postcranial skeleton and a partial skull with dentition, is the best-preserved symmetrodont mammal yet discovered. It provides a new insight into the relationships of the major lineages of mammals and the evolution of the mammalian skeleton. Our analysis suggests that this new taxon represents a part of the early therian radiation before the divergence of living marsupials and placentals; that therians and multituberculates are more closely related to each other than either group is to other mammalian lineages; that archaic therians lacked the more parasagittal posture of the forelimb of most living therian mammals; and that archaic therians, such as symmetrodonts, retained the primitive feature of a finger-like promontorium (possibly with a straight cochlea) of the non-therian mammals. The fully coiled cochlea evolved later in more derived therian mammals, and is therefore convergent to the partially coiled cochlea of monotremes.

[The experimental studies of immune response of antigen-extracted bovine cancellous bone grafting]

Xenogeneic bone grafting is an alternative to autogeneic bone grafting, but the intense immune rejection makes its clinical practice limited. We performed lymphocytes proliferation assay, enzyme-linked immunosorbent assay, and histological observation to evaluate the levels of cellular and humoral immunity, and the tissue reaction to the grafting of BALB/c mice receiving fresh bovine cancellous bone (FCB), antigen-extracted bovine massive cancellous bone (MCB), antigen-extracted bovine granular cancellous bone (GCB). Lymphocyte proliferation was increased in an early phase of the grafting and persisted for a long period in FCB group. Meanwhile higher levels of specific antibody were detected. In MCB and GCB groups, lymphocyte proliferation and specific antibody production were not ascended and no significant difference was observed between MCB and GCB groups in these immunological responses. There were no appreciable histologic signs of immune or foreign body reaction both in MCB and GCB groups. The results suggested that MCB, GCB were characterized less antigenicity and can be used as osteoconductive material or a carrier of bone growth factors.

[Determination of sulpride in human plasma by high performance liquid chromatography]

This paper describes a reliable method for the pharmacokinetic study of Sulpride in human plasma by reversed-phase high performance liquid chromatography. To compensate the loss of Sulpride during the extraction procedure we used an internal standard very similar in chemical structure and UV absorbance to those of Sulpride. The mobile phase was methanol-water-acetic acid (60:30:1) with a flow rate of 1.2 mL/min. A UV detector was used at 290 nm. The linear range was 5-100 mg/L and the detectable limit was 1.0 mg/L. The recovery and RSD were 97.95%-99.96% and 2.6%-5.1% respectively. The results showed that this method is a sensitive and accurate one which makes the pharmacokinetic study of Sulpride possible. If the concentration was too low to be detected by UV monitor, a fluorescence detector could be used with the excitation wavelength at 299 nm and emission at 342 nm. We analyzed the plasma samples from 30 day-treated psychotic patients and got the satisfactory results.

[Effects of different dilution of specific antibodies against the cell surface protein P1 of S. mutans MT 6R upon its adherence]

The sera and saliva were obtained from BALB/C mice by injection of the cell surface protein P1 and Freud's adjuvant. High antibody titers were showed in the sera and saliva by an enzyme-linked immunosorbent assay. Different dilution of the specific antibodies against the protein P1 of S. mutans had different inhibition effects on adhering of S. mutans MT 6R. Adherence of streptococcus mutans MT 6R on saliva-coated hydroxyapatite was reduced significantly by using sera and salivary antibodies in dilution of 1:1, 1:2, 1:4, 1:8, 1:16, 1:32 (P < 0.05).

[Effects of specific antibodies against the cell surface protein P1 of streptococcus mutans MT 6R upon adhered streptococci]

The sera and saliva were obtained from BALB/C mice by injection of the cell surface protein P1 and Freud's adjuvant. High antibody titers were showed in the sera and saliva by an enzyme-linked immunosorbent assay. The cells of S. mutans (serotype c, e and f) adhered on saliva-coated hydroxyapatite could be detached by the antibodies of the protein P1 of S. mutans MT 6R including in the sera and saliva (P < 0.05), but the antibodies had no influence on the cells of S. cricetus AHT, S. sobrinus OMZ176, S. sobrinus 6715 and S. rattus BHT (P > 0.05).

Awareness of donor alloantigens in antiadhesion therapy induces antigen-specific unresponsiveness to islet allografts

BACKGROUND

Antiadhesion therapy using monoclonal antibodies (mAbs) to adhesion molecules in vivo has been shown to produce significant prolongation of graft survival in various transplantation models. However, it remains unclear whether antiadhesion therapy operates by merely blocking adhesion between antigen-presenting cells and T cells physically and/or by blocking costimulatory signals while preserving signals mediated through T-cell receptors in vivo. We examined antigen-specific T-cell responses during and after antiadhesion therapy.

METHODS

BALB/c islets were transplanted into the renal subcapsular space of streptozotocin-induced diabetic C57BL/6 mice given anti-lymphocyte function-associated antigen (LFA)-1 and/or anti-intercellular adhesion molecule-1 mAb treatment. The animals bearing surviving islet allografts were challenged with BALB/c or third-party islets on day 7 or more than 100 days after transplantation.

RESULTS

Islet allografts were acutely rejected in untreated animals, with a mean survival time (MST) of 19+/-8 days. Administration of anti-LFA-1 mAb induced significant prolongation of graft survival with a mean survival time of 72+/-33 days, and half of the allografts showed indefinite survival. The animals given anti-LFA-1 mAb alone 7 days before transplantation showed acute rejection of BALB/c islets, whereas a significant number of animals given anti-LFA-1 mAb and the BALB/c islet allograft simultaneously accepted secondary BALB/c islets, but rejected third-party islets. Likewise, most of the animals bearing long-term functioning BALB/c allografts for more than 100 days accepted secondary BALB/c islets, but rejected C3H islets acutely. Interestingly, the spleen cells from these animals transferred unresponsiveness to BALB/c islets into the 2.5-Gy x-irradiated recipients, whereas those from naive animals induced acute rejection.

CONCLUSIONS

These results indicate that anti-LFA-1 mAb treatment prevents T-cell activation leading to rejection, but results in a T-cell receptor engagement leading to antigen-specific unresponsiveness maintained by transferrable suppressor cells.

Vascular endothelial growth factor attenuates myocardial ischemia-reperfusion injury

BACKGROUND

Hypoxic endothelial cell activation plays a key role in the myocardial dysfunction resulting from ischemia-reperfusion injury. Recent evidence suggests that vascular endothelial growth factor (VEGF) may, in addition to promoting angiogenesis, modulate various aspects of endothelial function and repair. We examined whether administration of VEGF in the cardioplegic solution might have a beneficial effect on myocardial ischemia-reperfusion injury in an isolated rat heart model.

METHODS

Hearts from Sprague-Dawley rats were perfused with Krebs-Henseleit solution in a modified Langendorff apparatus. Percent recovery of cardiac output, coronary flow, stroke work, and percent increase in coronary vascular resistance were measured after 2 hours of global ischemia and 40 minutes of reperfusion. Coronary effluent was collected after ischemia and reperfusion for measurement of creatine kinase.

RESULTS

Hearts receiving cardioplegia solution containing 125 microg VEGF showed significantly improved recovery of cardiac output, coronary flow, and stroke work, and significantly reduced coronary vascular resistance compared with hearts receiving hyperkalemic cardioplegia only (p < 0.05). Coadministration of a nitric oxide synthase inhibitor attenuated the VEGF-induced cardiprotective effects. Hearts treated with VEGF released significantly less creatine kinase compared with control hearts.

CONCLUSIONS

Addition of VEGF to hyperkalemic cardioplegia protects against myocardial ischemia-reperfusion injury in the isolated rat heart.

Further characterization of the major and minor rabbit FMO1 promoters and identification of both positive and negative distal regulatory elements

Previously, two promoters were identified for the rabbit FMO1 gene: a major, upstream promoter (P0) that initiates transcription from exon 0 and a second, minor promoter (P1) located approximately 200 bp downstream and initiating transcription from exon 1. Transcription initiation from the P0 promoter results in elimination of the exon 1 leader sequence from the mature transcript. In this report, we further define the major promoter and identify several positive and negative upstream regulatory domains employing deletion analysis and transient expression in HepG2 cells. Of interest, P0 and P1 were equally active in these assays. A 49-bp fragment spanning position -41 to +8 was found essential for the activity of P0 and also capable of basal transcriptional activity. Interestingly, this same 49-bp region was found necessary for P1 activity. Upstream of P0, three positive regulatory regions (positions -348 to -176, -757 to -584, and -1196 to -829) and two negative regulatory regions (positions -2120 to -1724 and 829 to -757) were identified using deletion mutants. Both P0 and P1 share the most proximate, positive regulatory domain but were regulated differentially by more distal 5' sequences. In addition to the upstream regulatory sequences, a potent negatively acting element was observed within intron 1. Using DNA fragments representing the most potent positive (position -348 to -176) and negative (position -829 to -757) regulatory sequences as probes, we demonstrate the formation of multiple specific DNA/protein complexes with protein factor(s) present in HepG2 nuclear extract.

Molecular modeling of interleukin-8 receptor beta and analysis of the receptor-ligand interaction

A structural model of interleukin-8 receptor type beta (IL-8R-beta) was constructed based on the structure of bacteriorhodopsin. High temperature molecular dynamics simulations were performed to search the possible conformations of loop regions in IL-8R-beta which recognize the ligand. The crystal structure of interleukin 8 (IL-8) was used as a geometric constraint of the extracellular loop regions of IL-8R-beta in the conformational search. 500 complex structures were extracted from the dynamics trajectory and five plausible models were selected based on the binding energy and known experimental data. To study further the interaction between IL-8R-beta and its ligands, the complex of IL-8R-beta and platelet factor 4 (PF4) C-terminal peptide was also modeled by molecular dynamics simulations. From these models, the N-terminus, extracellular domain 3 and extracellular domain 4 of IL-8R-beta were found to be important for ligand binding. Key residues of these regions involved in ligand binding were characterized. These models provide insight into the structural basis of biological activity of IL-8 and PF4 and may guide the design of potential therapeutic agents targeting IL-8 receptors. Furthermore, the approach developed from this study may have implications for the understanding of other chemokine receptor-ligand interactions that have been recently suggested to be involved in HIV infection.

[Diagnosis and surgical management of 22 patients with congenital coronary artery fistula]

Twenty-two patients underwent surgical treatment of coronary artery fistulas. The right coronary artery was the most common vessel of origin (68.2%), and the most frequent drainage site was the right ventricle (45.4%). The operation was performed with the use of extracorporeal circulation in 21 patients. Only one patient underwent distal ligation without the use of extracorporeal circulation. The absence of operative mortality and severe postoperative complication provide clear indications for surgical treatment. In view of currently improved and standardized techniques of extracorporeal circulation, we believe that it should be employed routinely.

Expression of herpes virus thymidine kinase in Neurospora crassa

The expression of thymidine kinase in fungi, which normally lack this enzyme, will greatly aid the study of DNA metabolism and provide useful drug-sensitive phenotypes. The herpes simplex virus type-1 thymidine kinase gene ( tk ) was expressed in Neurospora crassa. tk was expressed as a fusion to N.crassa arg-2 regulatory sequences and as a hygromycin phosphotransferase-thymidine kinase fusion gene under the control of cytomegalovirus and SV40 sequences. Only strains containing tk showed thymidine kinase enzyme activity. In strains containing the arg-2 - tk gene, both the level of enzyme activity and the level of mRNA were reduced by growth in arginine medium, consistent with control through arg-2 regulatory sequences. Expression of thymidine kinase in N.crassa facilitated radioactive labeling of replicating DNA following addition of [3H]thymidine or [14C]thymidine to the growth medium. Thymidine labeling of DNA enabled demonstration that hydroxyurea can be used to block replication and synchronize the N.crassa mitotic cycle. Strains expressing thymidine kinase were also more sensitive than strains lacking thymidine kinase to anticancer and antiviral nucleoside drugs that are activated by thymidine kinase, including 5-fluoro-2'-deoxyuridine, 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-iodouridine and trifluorothymidine. Finally, expression of thymidine kinase in N. crassa enabled incorporation of bromodeoxyuridine into DNA at levels sufficient to separate newly replicated DNA from old DNA using equilibrium centrifugation.

A natural motif approach to protein design: a synthetic leucine zipper peptide mimics the biological function of the platelet factor 4 protein

The design of smaller functional mimics of large proteins has long been an important challenge. In this study we use the natural leucine zipper as a structural template to design a 31-residue peptide analog that mimics the function of the larger platelet factor 4 (PF4) protein. The heparin binding activity of PF4 has been introduced into an unrelated leucine zipper sequence only by virtue of incorporating four lysines of PF4. Circular dichroism and binding experiments have shown that the designed leucine zipper peptide adopts a stable helical conformation and shows significant PF4-like heparin binding activity. These results strongly suggest that the lysine residues play an important role in the binding of PF4 to heparin. The de novo generation of the PF4 function in a designed leucine zipper peptide demonstrates that the leucine zipper motif is a useful scaffold for the design of functional peptides and proteins.

Clinical observations on 278 cases of cervical spondylopathy treated with electroacupuncture and massotherapy

From Dec. 1990 to Dec. 1993, 278 cases of cervical spondylopathy were treated with electroacupuncture and massotherapy. The cure rate was 82.7%; but in the control group, it was only 61%, indicating that electroacupuncture may enhance the cure rate (P < 0.05). Of the 278 cases treated by three to five sessions, the pain and numbness disappeared in about 96% of the patients.

Active nuclear transport of chicken lipovitellin-2

Chicken lipovitellin-2 is a small, approximately 30 kDa yolk protein, derived from the intracellular breakdown of the precursor protein vitellogenin. In principle, lipovitellin-2 is small enough to directly diffuse into the nucleus. Our results, however, demonstrate that its nuclear transport is an active process which can be inhibited by wheat germ agglutinin, chilling, and energy depletion. The N-terminal sequence analysis identifies chicken lipovitellin-2 beginning at Ala1544 in the C-terminal region of vitellogenin yielding of protein of 30,982 Da.

Cingulate cortex synaptic terminal proteins and neural cell adhesion molecule in schizophrenia

The neuronal organization and patterns of afferent innervation are abnormal in the cingulate cortex in schizophrenia, and associated changes in synaptic terminals could be present. A panel of monoclonal antibodies was defined with biochemical and fusion protein studies as detecting syntaxin (antibody SP6), synaptophysin (antibody SP4) and synaptosomal-associated protein-25 (antibody SP12). These antibodies and a polyclonal antibody reactive with neural cell adhesion molecule were used to investigate the cingulate cortex in schizophrenia. Immunocytochemistry indicated that syntaxin immunoreactivity had a considerably wider distribution than synaptophysin. Overall, multivariate analysis indicated increased synaptic terminal protein immunoreactivity in schizophrenia compared to controls (P=0.004). Controlled for age and post mortem interval, syntaxin immunoreactivity was significantly elevated in schizophrenia (P=0.004), and neural cell adhesion molecule immunoreactivity was also elevated (P=0.05). The neural cell adhesion molecule to synaptophysin ratio was increased (P=0.005), possibly indicating the presence of less mature synapses in schizophrenia. Elevated syntaxin immunoreactivity is consistent with increased glutamatergic afferents to the cingulate cortex in schizophrenia, and combined with the neural cell adhesion molecule to synaptophysin ratio results suggests that synaptic function in this region in schizophrenia may be abnormal.