A short daytime nap modulates levels of emotions objectively evaluated by the emotion spectrum analysis method

A novel objective technique, the emotion spectrum analysis method, was first applied to investigate emotional fluctuations before, during and after a daytime nap in eight healthy young adults (four males and four females). The subjects were allowed to freely nap between 13.00 and 14.00 h, in which stages 1 and 2 non-rapid eye movement sleep occurred on average for 5.9 and 20.8 min, respectively. Emotional components such as anger, joy, relaxation and sadness were numerically estimated on the basis of spatio-temporal behavior of 21-channel electroencephalogram and analyzed statistically. In comparison with the prenap waking level, the magnitudes of the anger, joy and relaxation components remained stably unchanged during the nap but elevated significantly during the postnap waking period. The sadness component exhibited little significant change throughout the observation period. From the results, we suggest that a short daytime nap modulates the emotions to improve the postnap mental states.

[Preliminary study of clinical scoring on prognosis of severe head-injury]

In this article, 68 cases of severly head-injured patients scoring and prognosis evaluation were reviewed. We have come to a practicable severe head injury index (SHII) for first aid: the blood pressure (Bp), pulse rate (P), respiration rate (R), degree of consciousness and reaction of the pupils are five items taken for estimation of the patients. The highest total score was 25, the lowest was 5. If the score was lasted for 2-4 hours below 7, and first aid non-responsive in 4-6 hours, the mortality and morbidity rates will be high. When the score is more than 14, the first aid salvage will be meaningful. The first aid salvage will be meaningful. The first aid had significant measing especially for those patients whose score was over 18. The detailed method of clinical scoring is shown on chart 2.

Transduction of human IL-9 receptor cDNA into TF1 cells induces IL-9 dependency and erythroid differentiation

Human growth factor-dependent cell line TF1, which lacks interleukin (IL)-9 receptors (R) and does not grow in IL-9, was transduced with a retroviral vector containing human IL-9R cDNA and a selection marker. An IL-9-dependent TF1 cell line, which could also grow in other cytokines, was established after selection in G418 and could produce mature RBC in response to cytokine stimulation. TF1 cells transduced with the same viral vector without the IL-9R insert cDNA (mock control) and then selected responded the same as nontransduced TF1 cells. They failed to grow in response to IL-9 and did not generate RBC. An increased number and size of burst-forming units-erythroid (BFU-E)-like colonies were detected from IL-9R-transduced TF1 cells, compared with mock-transduced cells, in response to erythropoietin (EPO) and IL-9. To evaluate self-renewal and differentiation capacity, colony-replating assays were performed in the presence of IL-3, GM-CSF, IL-9, and EPO. After four replatings, the cloning efficiency of IL-9R-transduced TF1 cells decreased from 98% to 38%, most likely due to terminal erythroid cell differentiation. In contrast, no change in replating efficiency was detected in mock-transduced cells. TF1 cells stably expressing IL-9R and responding to IL-9 can serve as a cell line model to study the intracellular signals mediating IL-9-induced erythroid cell proliferation and differentiation.

[Clinical pathology of Dubin-Johnson syndrome]

OBJECTIVE

To investigate the property of pigment granules in the hepatocytes in patients with Dubin-Johnson syndrome.

METHOD

Light microscopy, histochemical, immnohistochemical and electron microscopy techniques were used to study the pigment glanules and the expression of S-100 protein and HMB45 in hepatocytes.

RESULTS

Histological examination revealed normal lobular architecture and the abundont brown pigments which were chiefly seen in the centrilobular zone hepatocytes. The pigment granules were evidenced to have the characterization of both lipofuscin and melanin by histochemical staining and ultrastructural studies and to have the featurts of the melanin by immnohistochemical staining.

CONCLUSION

The results suggest that the pigment graunles are lipfuscin-melanin complex in the hepatocytes in patients with Dubin-Johnson syndrome.

Structure-based discovery of small molecule inhibitors targeted to protein tyrosine phosphatase 1B

Protein tyrosine phosphatases (PTPases) are involved in the control of tyrosine phosphorylation levels in the cell and are believed to be crucial for the regulation of a multitude of cellular functions. A detailed understanding of the role played by PTPases in various signaling pathways has not yet been achieved, and potent and selective PTPase inhibitors are essential in the quest to determine the functionality of individual PTPases. Using the DOCK methodology, we have carried out a structure-based, computer-assisted search of an available chemical database in order to identify low molecular weight, nonpeptidic PTP1B inhibitors. We have identified several organic molecules that not only possess inhibitory activity against PTP1B but which also display significant selectivity for PTP1B. This indicates that although structural features important for pTyr recognition are conserved among different PTPases, it is possible to generate selective inhibitors targeted primarily to the catalytic site. Kinetic analysis and molecular modeling experiments suggest that the PTP1B active site possesses significant plasticity such that substituted and extended aromatic systems can be accommodated. The newly identified molecules provide a molecular framework upon which therapeutically useful compounds can ultimately be based, and systematic optimization of these lead compounds is likely to further enhance their potency and selectivity.

Analysis of adenoviral transport mechanisms in the vessel wall and optimization of gene transfer using local delivery catheters

Local delivery devices have been used for adenovirus-mediated gene transfer to the arterial wall for the potential treatment of vascular proliferative diseases. However, low levels of adenoviral gene expression in vascular smooth muscle cells may pose a serious limitation to the success of these procedures in the clinic. In this study, we examined the mechanisms controlling adenoviral transport to the vessel wall, using both hydrogel-coated and infusion-based local delivery catheters, with the goal of enhancing in vivo gene transfer under clinically relevant delivery conditions. The following delivery parameters were tested in vivo: applied transmural pressure, viral solution volume and concentration, and delivery time. We found that viral particles are transported into the vessel wall in a manner consistent with diffusion rather than pressure-driven convection. Consistent with diffusion, viral concentration was shown to be the key variable for viral transport in the vessel wall and thus gene expression in vascular smooth muscle cells. A transduction level of 17.8+/-3.2% was achieved by delivering a low volume of concentrated adenoviral beta-galactosidase solution through an infusion balloon catheter at low pressure without an adverse effect on medial cellularity. Under these conditions, effective gene transfer was accomplished within a clinically relevant time frame of 2 min, indicating that longer delivery times may not be necessary to achieve efficient gene transfer.

Glass needle-mediated microinjection of macromolecules and transgenes into primary human blood stem/progenitor cells

A novel glass needle-mediated microinjection method for delivery of macromolecules, including proteins and larger transgene DNAs, into the nuclei of blood stem/progenitor cells was developed. Temporary immobilization of cells to extracellular matrix-coated dishes has enabled rapid and consistent injection of macromolecules into nuclei of CD34(+), CD34(+)/CD38(-), and CD34(+)/CD38(-)/Thy-1(lo) human cord blood cells. Immobilization and detachment protocols were identified, which had no adverse effect on cell survival, progenitor cell function (colony forming ability), or stem cell function (NOD/SCID reconstituting ability). Delivery of fluorescent dextrans to stem/progenitor cells was achieved with 52% +/- 8.4% of CD34(+) cells and 42% +/- 14% of CD34(+)/CD38(-)cells still fluorescent 48 hours after injection. Single-cell transfer and culture of injected cells has demonstrated long-term survival and proliferation of CD34(+) and CD34(+)/CD38(-) cells, and retention of the ability of CD34(+)/CD38(-) cells to generate progenitor cells. Delivery of DNA constructs (currently </= 19.6 kb) and fluorescently labeled proteins into CD34(+) and CD34(+)/CD38(-) cells was achieved with transient expression of green fluorescent protein observed in up to 75% of injected cells. These data indicate that glass needle-mediated delivery of macromolecules into primitive hematopoietic cells is a valuable method for studies of stem cell biology and a promising method for human blood stem cell gene therapy. (Blood. 2000;95:437-444)

Molecular modeling and site-directed mutagenesis of CCR5 reveal residues critical for chemokine binding and signal transduction

The CC chemokine receptor CCR5 is the receptor for several chemokines and coreceptor for the entry of HIV-1. Whereas many studies focus on CCR5 interaction with HIV-1, residues in CCR5 important for chemokine binding and subsequent signal transduction remain poorly understood. Here we use an approach combining protein structure modeling and site-directed mutagenesis to probe the structure of CCR5 and its interactions with chemokine ligands and HIV-1. Structural models of CCR5 rationalize extensive biological data about the role of CCR5 in HIV-1 envelope glycoprotein gp120 binding and HIV-1 entry. Furthermore, we carry out site-directed mutagenesis guided by structural analysis of the complex of CCR5 and a chemokine. This leads to the novel observation that certain residues, such as Tyr10 and Lys26, in the N terminus of CCR5 play a critical structural role for ligand binding and signaling. Single glycine substitution of these residues significantly decreases chemokine binding and signal transduction. These results provide new insight into the structural basis for CCR5 receptor-ligand interaction and may guide the design of novel inhibitors.

[Changes of PMN apoptosis in rabbits after burn]

OBJECTIVES

To study the dynamic changes of apoptosis of PMN from rabbits in the early stage after severe burn in vivo and investigate the effect of burn serum and wound exudate on PMN apoptosis in vitro.

METHODS

12 rabbits were randomly divided into 2 groups: control group (37 degrees C) and burn group (95 degrees C, 15 sec, III degrees 30% TBSA). Whole blood from the burn group at 0, 4, 8, 12, 24 h postburn was stained with acridine orange/ethidium bromide (AO + EB), and observed under UV microscopy. PMNs were isolated from both groups and cultured for 24 h (37 degrees C, 5% CO(2)) with normal serum (NS), burn serum (BS), and subeschar tissue fluid (STF) respectively. Morphological assessment and quantitation of apoptosis were performed with AO + EB stain and flow cytometric analysis.

RESULTS

The number of apoptotic PMN in vivo decreased in the early stage postburn. In the BS + PMN group and STF + PMN group, the percentage of apoptotic PMN reduced (vs NS + PMN group, P < 0.05) and the specific DNA "ladder" pattern for apoptotic cells was not detected by agarose gel electrophoresis. We observed that both burn serum and STF could similarly suppressed PMN apoptosis while there was no significant difference between NS + normal PMN group and NS + burn PMN group.

CONCLUSIONS

Apoptosis is inhibited in PMN from rabbits postburn in the early stage. Both burn serum and STF from rabbits postburn can inhibit PMN apoptosis in vitro.

The roles of side chain and backbone in protein structure probed with glycine- and sarcosine-rich synthetic leucine zipper peptides

The protein folding problem has long been a formidable challenge. Here we present a synthetic natural motif approach that exploits small preexisting structural models for the dissection of forces important in protein folding. An example for this approach is shown in the modification of a 31-residue leucine zipper peptide with the helix-breaking amino acid glycine and the hydrogen bond-breaking imino acid sarcosine. Circular dichroism and NMR experiments have shown that the glycine-modified leucine zipper peptide adopts a stable helical conformation similar to the native conformation while the sarcosine-modified leucine zipper peptide adopts a random coil conformation. These results provide valuable insight into the current controversy over the relative importance of long-range side chain-side chain interactions versus local backbone interactions in protein structure and suggest that the natural motif strategy may represent a useful model to study protein folding.

Regulation of smooth muscle cell migration and integrin expression by the Gax transcription factor

Homeobox transcription factors specify body plan by regulating differentiation, proliferation, and migration at a cellular level. The homeobox transcription factor Gax is expressed in quiescent vascular smooth muscle cells (VSMCs), and its expression is downregulated by vascular injury or other conditions that lead to VSMC proliferation. Previous investigations demonstrate that Gax may regulate VSMC proliferation by upregulating the cyclin-dependent kinase (cdk) inhibitor p21. Here we examined whether Gax influences VSMC migration, a key feature in the development of stenotic lesions after balloon injury. Transduction of a Gax cDNA inhibited the migratory response of VSMCs toward PDGF-BB, basic fibroblast growth factor, or hepatocyte growth factor/scatter factor. Gax expression also inhibited migration of NIH.3T3 fibroblasts and embryonic fibroblasts lacking p53. Gax was unable to inhibit the migration of fibroblasts lacking p21, but this effect could be restored in these cells by providing exogenous p21 or by overexpressing another cdk inhibitor, p16. Flow cytometric analysis implicated a Gax-mediated downregulation of alpha(v)beta(3) and alpha(v)beta(5) integrin expression in VSMCs as a potential cause for reduced cell motility. Gax specifically downregulated beta(3) and beta(5) in VSMCs in culture and after acute vascular injury in vivo. Repression of integrin expression was also found in NIH 3T3 cells and p53 knockout fibroblasts, but not in p21-knockout fibroblasts, unless these cells express exogenous p21 or p16. These data suggest that cycle progression, integrin expression, and cell migration can be regulated in VSMCs by the homeobox gene product Gax.

[Combined use of rhBMP2/BCB and free periosteum in repairing segmental defects in radii of rabbits]

OBJECTIVE

To study the efficacy of combined use of rhBMP2/BCBand free periosteal graft in repairing segmental bony defects.

METHODS

A new grafting material (rhBMP2/BCB) was made by combining recombinant human BMP2 (rhBMP2) and an antigen-free bovine cancellous bone (BCB) as a carrier. rhBMP2/BCB was used alone in conjunction with free periosteal graft to repair a 1.5 cm defect in the radius of the rabbit. The defect-repairing capability for each of the treatment modalities was assessed radiographically, biomechanically, and by densitometry and histological studies.

RESULTS

rhBMP2/BCB used alone was capable of healing the defect in large by 16 weeks, with a similar repair process and mechanism seen with RBX. Combined use of rhBMP2/BCB and free periosteal graft was superior in terms of increased amount and quality of the new bone formed at the early stage of the repair process (within 12 weeks) to rhBMP2/BCB used in isolation, with the defect basically healed by 12 weeks.

CONCLUSIONS

Both methods are effective in repairing segmental bony defects, with rhBMP2/BCB used in conjunction with free periosteal graft being most preferred, considering the satisfactory osteogenesis, osteoconduction and osteoinduction.

A neural network approach to the biopsy diagnosis of early acute renal transplant rejection

AIMS

To develop and test a neural network to assist in the histological diagnosis of early acute renal allograft rejection.

METHODS AND RESULTS

We used three sets of biopsies to train and test the network: 100 'routine' biopsies from Leicester; 21 selected difficult biopsies which had already been evaluated by most of the renal transplant pathologists in the UK, in a study of the Banff classification of allograft pathology and 25 cases which had been classified as 'borderline' according to the Banff classification in a review of transplant biopsies from Oxford. The correct diagnosis for each biopsy was defined by careful retrospective clinical review. Biopsies where this review did not provide a clear diagnosis were excluded. Each biopsy was graded for 12 histological features and the data was entered into a simple single layer perception network, designed using the MATLAB neural network toolbox. Results were compared with logistic regression using the same data, and with 'conventional' histological diagnosis. If the network was trained only with the 100 'routine' cases, its performance with either of the other sets was poor. However, if either of the 'difficult' sets was added to the training group, testing with the other 'difficult' group improved dramatically; 19 of the 21 'Banff' study cases were diagnosed correctly. This was achieved using observations made by a trainee pathologist. The result is better than was achieved by any of the many experienced pathologists who had previously seen these biopsies (maximum 18/21 correct), and is considerably better than that achieved by using logistic regression with the same data.

CONCLUSION

A neural network can provide a considerable improvement in the diagnosis of early acute allograft rejection, though further development work will be needed before this becomes a routine diagnostic tool. The selection of cases used to train the network is crucial to the quality of its performance. There is scope to improve the system further by incorporating clinical information. Other related areas where this approach is likely to be of value are discussed.

Attachment of C-terminus of SDF-1 enhances the biological activity of its N-terminal peptide

The N-terminus of stromal cell-derived factor 1 (SDF-1) is known to be a critical site for CXCR4 receptor binding and signaling. However, the functional role of other regions, in particular the C-terminal helix of SDF-1, has yet to be defined. In this study, we designed and synthesized a peptide model of SDF-1 containing its N- and C-terminal regions. The attachment of the C-terminus of SDF-1, which by itself had no activity in receptor binding and signaling, dramatically increased the effect of the N-terminal fragment in inducing chemotaxis and intracellular Ca(2+) influx in sup T1 cells compared with the peptide containing only the N-terminal sequence. The enhancement in activity was not due to the increase in receptor affinity as the N,C-terminal peptide did not show higher CXCR4 binding than the N-terminal peptide. On the other hand, the intracellular Ca(2+) influx activated by the N,C-terminal peptide, but not the N-terminal peptide, was completely abolished by the addition of heparin, suggesting that the C-terminal fragment of the peptide binds glycosaminoglycans (GAGs) and exerts an effect to modulate biological activity. These data raise the possibility that the C-terminus in native SDF-1 is one of interaction sites with GAGs and may be associated with biological function of SDF-1. Furthermore, this study demonstrates an approach for the design of novel agonists or antagonists of other chemokine receptors that possess enhanced biological activity.

The role of positively charged residues in CXCR4 recognition probed with synthetic peptides

A high positive charge is the common characteristic shared by the beta-sheet region of stromal cell-derived factor-1 (SDF-1) and CXCR4 antagonists such as ALX40-4C consisting of nine D-arginines. This raises the question that the positively charged residues may play a role in recognition of CXCR4. To test this hypothesis, two studies were carried out using synthetic peptides. In the first study, peptide analogs possessing amino acid sequences from both the N-terminus and the beta-sheet region of SDF-1 were used as models to study the functional role of the beta-sheet region of SDF-1. The attachment of positively charged residues to the N-terminal peptide sequence of SDF-1 was found to enhance the ability of the peptides in CXCR4 binding and inhibiting CXCR4-mediated T-tropic HIV-1 entry. In the second study, two peptides containing nine arginines and the N-terminal signal sequence of SDF-1 were used as models to study the receptor binding mechanism of CXCR4 antagonists of high positive charges such as ALX40-4C. One peptide did not show signaling activity as indicated by the lack of calcium influx while another peptide induced unusual calcium influx distinct from that induced by the SDF-1 N-terminal peptide. In addition, the signal induced by the SDF-1 N-terminal peptide was inhibited by ALX40-4C. Therefore, the first study provides experimental support for the role of the highly positive beta-sheet region of SDF-1 in CXCR4 binding. The second study suggests that the binding site of ALX40-4C in CXCR4 may partially overlap with that of the SDF-1 N-terminal peptide. Both findings should be valuable for the design of SDF-1 agonists and antagonists.

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.