[The effect analysis of tuberculosis control project loaned by World Bank in Guangdong province]

OBJECTIVE

To evaluate the effect of tuberculosis control project loaned by World Bank in Guangdong province.

METHODS

The registration and the treatment effect of pulmonary tuberculosis patients according to Guangdong tuberculosis report were analyzed.

RESULTS

The above program had been conducted widespread since 1995. Over the past five years, 601,913 cases of suspicious tuberculosis patients have been received and diagnosed, in which 111,164 infectious patients (containing 91,612 newly-attacked infectious cases) were found. Just in 1999, the number of newly-attacked infectious patients was 1.2 times to that(19,858 newly-attacked infectious cases) of 1981-1990 prior to this program. And the average cure rate of infectious patients reached to 95.2%. The cure rate showed an uptrend amounting to 97.2% from 87.6%.

CONCLUSION

Satisfactory effect have been achieved by the World-Bank loaned TB control project in Guangdong province.

Retrovirus molecular conjugates. A novel, high transduction efficiency, potentially safety-improved, gene transfer system

Two significant barriers limit the use of amphotropic retrovirus for human gene transfer protocols: 1) low transduction efficiency in cells with low receptor expression and 2) safety concerns originating from the risk of formation and propagation of replication competent virus in vivo. In principle, if ecotropic retrovirus, which is incapable of infecting human cells, could be transiently modified to effectively transduce human cells, this safety risk could be alleviated. Here we demonstrate that formation of amphotropic retrovirus polylysine molecular conjugates (aMMLV-PL) enhanced gene transfer up to 10-fold in a variety of human cell lines over the equivalent of unconjugated vector (aMMLV). The polylysine modification and formation of ecotropic retrovirus molecular conjugates (eMMLV-PL) permitted effective and stable transduction of different human cell lines as well as primary human bone marrow stroma cells at frequencies of greater than 80%. It is conceivable that this novel ecotropic-based conjugate retrovirus vector could also potentially provide enhanced safety characteristics not only over amphotropic retrovirus vectors but also over genetically tropism-modified recombinant ecotropic vectors. In contrast to genetic modifications, physical or chemical modifications are not propagated. Thus, formation of replication competent eMMLV from conjugates would be self-limited and would not result in virus propagation in humans.

Microarray analysis of Tbx2-directed gene expression: a possible role in osteogenesis

Tbx2 is a member of the developmentally important transcriptional regulatory T-box gene family, whose target genes have not been well characterized. In an attempt to identify genes that may be regulated by Tbx2, mouse cDNA microarrays were used to analyze differential gene expression profiles, comparing stably transfected NIH3T3 cells overexpressing Tbx2 and vector-transfected controls. Among 8734 genes, 107 genes were up-regulated by 2-fold or greater, and 66 genes were down-regulated by 2-fold or greater. Caveolin, pleiotrophin (osf-1), osteoblast-specific factor-2 (osf-2) and collagen type I alpha were among the genes upregulated in the Tbx2-overexpressing cells, whereas cadherin 3, tenascin C, and insulin-like growth factor binding protein 10/CYR61 (IBP10) were among the genes downregulated. Northern blot analysis confirmed the correlation of expression of several genes, including IBP10 and osf-2, in fibroblast NIH3T3 and rat osteosarcoma ROS17/2.8 cells differentially expressing Tbx2. In ROS17/2.8 cells transfected with antisense Tbx2, osf-2 was downregulated, whereas transfection of sense Tbx2 upregulated this gene. Interestingly, the expression of pleiotrophin (osf-1) and collagen I alpha with Tbx2 transfection showed an inverse regulatory correlation between NIH3T3 and ROS17/2.8 cells. Thus, Tbx2 can act as both a repressor and activator, and the cellular context can influence the effect on gene expression. Although the data do not address whether Tbx2 directly mediates the transcriptional effect, a number of candidate genes possess putative T-box gene regulatory elements. The results support the hypothesis that Tbx2 may be an important modulator of bone development. Further functional cluster analysis indicates that Tbx2 might also be involved in the regulation of cell cycle and cell adhesion.

Glucose-dependent insulinotropic peptide is an integrative hormone with osteotropic effects

Glucose-dependent insulinotropic peptide (GIP) is a gut-derived hormone known to be important in modulating glucose-induced insulin secretion. In addition, GIP receptors are widely distributed and may have effects on multiple other tissues: fat cells, adrenal glands, endothelium and brain. We have demonstrated recently that GIP also has anabolic effects on bone-derived cells. We now demonstrate that GIP administration prevents the bone loss associated with ovariectomy. We propose that GIP plays a unique role in signaling the bone about nutrient availability, indicating the importance of the gut hormones in directing absorbed nutrients to the bone, and suggesting the concept of an 'entero-osseous axis'. Thus, GIP plays an integrative role helping coordinate efficient and targeted nutrient absorption and distribution.

[Retention of selenium volatility using lime in coal combustion]

For understanding the volatility of selenium, the effect of the contents of exchangeable cations of coal on it, and the retention of selenium using CaO in coal combustion, the sequential chemistry extraction, the fixed bed and circulating fluidized bed (CFB) combustion, X-ray diffraction (XRD) and atomic fluorescence spectrometry (AFS) were undertaken. The results showed that the volatility of selenium was more than 97% in coal combustion at 815 degrees C, and the volatility of selenium was affected by the content of exchangeable cations of coal in low-middle temperature. It was identified that lime can restrain the volatility of selenium. In fixed bed combustion of coal, the retention rates of selenium volatility were between 11.6% and 50.7% using lime. In circulating fluidized bed combustion of coal, partitioning of selenium changed very much in ash of different size fraction between without lime and with lime. Comparing with combustion without lime, the content of selenium in ash from chimney was less than fourth times and that in leaching water from chimney decreased by two orders of magnitude using lime. Retention of selenium volatility using lime is so effective in coal combustion, especially in CFB combustion of coal.

Low or no antibody responses to human immunodeficiency virus type 1 Nef in infected carriers with subtype E, in contrast to subtype B that showed antibodies preferentially recognizing subtype-specific Nef epitopes

The viral accessory gene product Nef has been shown to play an important role in human immunodeficiency virus type 1 (HIV-1)-induced pathogenesis. Only little information is available regarding the differences in the host immune responses against Nef protein and its function in vivo among different subtypes of HIV-1. In the present study, we showed marked differences in the immune responses to Nef protein between subtypes B and E. The amino acid sequence in subtype E Nef showed 72% homology with that in subtype B. Most murine monoclonal antibodies obtained by immunization with subtype B or E Nef protein showed cross-reactivity with both Nef proteins (80 and 67%, respectively). Next, we focused on the immune responses among infected Japanese and Thai individuals. Subtyping of the individuals into B and E was carried out by enzyme-linked immunosorbent assay (ELISA) using synthetic peptides corresponding to the V3 loop representing the principal neutralizing domain. Most of the sera from these individuals reacted strongly with Gag p24 proteins derived from subtypes B and E at similar levels. However, the immune responses among these individuals to Nef protein were markedly different. Some subtype B-infected Japanese and Thai individuals (40 and 35%, respectively) showed higher levels of anti-Nef antibodies, although these antibodies preferentially recognized epitopes specific to subtype B. On the other hand, most of the subtype E-infected Japanese and Thai individuals showed low or no antibody responses to Nef proteins. Thus, immune responses to Nef were markedly different between subtypes B- and E-infected carriers, suggesting different function(s) for Nef in AIDS pathogenesis. Further, vaccine design must take into account the different subtypes of HIV-1.

Functional analysis of glucose-dependent insulinotropic polypeptide fusion proteins

To generate functional fluorescently tagged glucose-dependent insulinotropic polypeptide (GIP), a series of GIP expression constructs were devised. These included G1 (complete preprohormone), G2 (lacking the C-terminal extension), G3 (lacking both N- and C-terminal extensions), G4 (G2 fused to green fluorescent protein, GFP), and G5 (G3 fused to GFP). Expression of G5 in bacteria generated immunopositive GIP together with GFP fluorescence, while G4 generated only fluorescence without immunoreactivity. Transfection of NIH3T3 cells with cDNAs of G1, G3, G5, but not G2, G4, and EGFP, resulted in immunologically detectable GIP formation, although fluorescence could be detected in the latter two. GIP as well as GIP-GFP secreted by NIH3T3 cells significantly stimulated intracellular cAMP accumulation and Ca(2+) mobilization in SaOS2 cells. The GIP receptor antagonist GIP(7-30) abolished these responses. These results suggest that a GIP-GFP fusion protein seven times larger than the native peptide retains function and may be used as an in vivo probe to detect GIP receptor distribution and to explore GIP's biological roles.

Structure and dynamics of excited electronic states at the adsorbate/metal interface: C6F6/Cu(111)

Excited state electron transfer at the adsorbate/metal interface represents a key step in molecular electronic devices. The dynamics of such processes are governed by ultrafast energy relaxation which can be probed directly by time-resolved two-photon photoemission (2PPE). Using 2PPE spectroscopy we investigate the energetics and lifetimes of the unoccupied electronic states of C6F6 adsorbed on Cu(111) as a model system for electron transfer at organic/metal interfaces. With increasing C6F6 layer thickness we find a pronounced decrease in the energetic position of the lowest unoccupied state, which is accompanied by a strong increase in its lifetime as well as a decrease in the effective electron mass. The frequently employed dielectric continuum model which describes delocalized (quantum well) states within adsorbate layers does not give a consistent explanation of these findings. By adsorption of Xe overlayers onto C6F6/Cu(111) we can show that, even for one monolayer of C6F6, the excited state must be localized predominantly inside the C6F6 layer and thus originates from a molecular state (presumably an antibonding sigma* orbital). With increasing coverage this state becomes more delocalized within the adsorbate layer, which reduces the coupling to the metal substrate and thus enhances the excited state lifetime.

Molecular ratio between borna disease viral-p40 and -p24 proteins in infected cells determined by quantitative antigen capture ELISA

We developed the antigen capture enzyme-linked immunosorbent assay (ELISA) systems for quantification of Borna disease virus (BDV) major antigens, p40 and p24. Using these ELISAs, we quantified the two proteins in various BDV-infected materials, including the cell lysates and culture supernatants as well as the homogenates of experimental animal brains. The ELISAs were also applied to measure the infectious titer of BDV in persistently infected cell lines. Quantitative analysis with these ELISAs allowed us to measure the molecular ratio between the p40 and p24 in infected samples. Interestingly, the ratio of p24 to p40 in persistently infected cells was much higher than that observed in acutely infected cells although the ratios in the supernatants from both cell lines were quite similar. BDV-inoculated gerbil brain cells showed a relatively high ratio of p24 to p40 as compared with acutely infected cells. These observations suggested that the molecular ratio between the proteins strongly depended on the infectious status of BDV in the host cells. The ELISA system developed here could be a convenient method for the quantification of BDV infection and may also be beneficial for understanding viral replication and infectious status in the host cells.

Fifty-six cases of protrusion of lumbar intervertebral disc treated by penetration and oral administration of Chinese decoction plus traction

Fifty-six cases of the protrusion of the lumbar intervertebral disc in the treatment group were treated by drug-penetration and oral administration of traditional Chinese decoction plus traction, and the other 35 cases in the control group by oral administration of Chinese decoction and traction. The results showed that the cure rate in the treatment group was 83.9%, and that in the control group was 57.1%, with a statistically significant difference between the two groups (P < 0.01), indicating that the former is a more effective therapy for protrusion of the lumbar intervertebral disc.

Transforming growth factor beta inhibits the phosphorylation of pRB at multiple serine/threonine sites and differentially regulates the formation of pRB family-E2F complexes in human myeloid leukemia cells

Transforming growth factor beta (TGFbeta)1 induced dephosphorylation of pRb at multiple serine and threonine residues including Ser249/Thr252, Thr373, Ser780, and Ser807/811 in MV4-11 cells. Likewise, TGFbeta1 caused the dephosphorylation of p130, while inhibiting accumulation of p107 protein. Phosphorylated pRb was detected to bind E2F-1 and E2F-3, which appears to be a major form of pRb complexes in actively cycling cells. TGFbeta1 significantly downregulated pRb-E2F-1 and pRb-E2F-3 complexes as a result of inhibition of E2F-1 and E2F-3. In contrast, complexes of E2F-4 with pRb and with p130 were increased markedly upon TGFbeta1 treatment, whereas p107 associated E2F-4 was dramatically decreased. In agreement with these results, p130-E2F-4 DNA binding activity was dominant in TGFbeta1 treated cells, whereas p107-E2F-4 DNA binding activity was only found in proliferating cells. Our data strongly suggest that inhibition of E2Fs and differential regulation of pRb family-E2F-4 complexes are linked to TGFbeta1-induced growth inhibition. E2F-4 is switched from p107 to p130 and pRb when cells are arrested in G1 phase by TGFbeta1.

Glucose-dependent insulinotropic peptide signaling pathways in endothelial cells

Glucose-dependent insulinotropic peptide (GIP) potentiates glucose-induced insulin secretion. In addition, GIP has vasoconstrictive or vasodilatory properties depending on the vascular bed affected. In order to assess whether this effect could be related to differences in GIP receptor expression, several different endothelial cell types were examined for GIP receptor expression. GIP receptor splice variants were detected and varied depending on the endothelial cell type. Furthermore, stimulation of these cells with GIP led to cell type dependent differences in activation of the calcium and cAMP signaling pathways. To our knowledge this is the first physiological characterization of receptors for GIP in endothelial cells.

Functional parathyroid hormone receptors are present in an umbilical vein endothelial cell line

Acute parathyroid hormone exposure induces vascular smooth muscle relaxation. In contrast, continuous infusion of parathyroid hormone leads to vasoconstriction and an elevation of blood pressure. Despite the known effects of parathyroid hormone on vascular smooth muscle, possible direct effects on the vascular endothelium have not previously been investigated. Using a human umbilical vein endothelial cell line, we found that parathyroid hormone increased both intracellular calcium and cellular cAMP content in these endothelial cells. Furthermore, exposure of these cells to increasing concentrations of parathyroid hormone stimulated both [(3)H]thymidine incorporation and endothelin-1 secretion. Parathyroid hormone/parathyroid hormone-related peptide receptor mRNA could be detected at low levels in these cells. In summary, these data demonstrate that endothelium-derived cells contain functional parathyroid hormone receptors. The potential physiological role of these receptors remains to be determined.

Molecular dynamics simulation of four-alpha-helix bundles that bind the anesthetic halothane

The mutation of a single leucine residue (L38) to methionine (M) is known experimentally to significantly increase the affinity of the synthetic four-alpha-helix bundle (Aalpha(2))(2) for the anesthetic halothane. We present a molecular dynamics study of the mutant (Aalpha(2)-L38M)(2) peptide, which consists of a dimer of 62-residue U-shaped di-alpha-helical monomers assembled in an anti topology. A comparison between the simulation results and those obtained for the native (Aalpha(2))(2) peptide indicates that the overall secondary structure of the bundle is not affected by the mutation, but that the side chains within the monomers are better packed in the mutant structure. Unlike the native peptide, binding of a single halothane molecule to the hydrophobic core of (Aalpha(2)-L38M)(2) deforms the helical nature of one monomer in a region close to the mutation site. Increased exposure of the cysteine side chain to the hydrophobic core in the mutant structure leads to the enhancement of the attractive interaction between halothane and this specific residue. Since the mutated residues are located outside the hydrophobic core the observed increased affinity for halothane appears to be an indirect effect of the mutation.

Molecular dynamics simulation of a hydrated diphytanol phosphatidylcholine lipid bilayer containing an alpha-helical bundle of four transmembrane domains of the influenza A virus M2 protein

An alpha-helical bundle composed of four transmembrane portions of the M2 protein from the Influenza A virus has been studied in a hydrated diphytanol phosphatidylcholine bilayer using molecular dynamics (MD) calculations. Experimentally, the sequence utilized is known to aggregate as a four-helix bundle and act as a pH-gated proton-selective ion channel, which is blocked by the drug amantadine hydrochloride. In the presented simulation, the ion channel was initially set up as a parallel four-helix bundle. The all-atom simulation consisted of almost 16,000 atoms, described classically, using a forcefield from the CHARMM22 database. Bilayers with and without the bundle were shown to be stable throughout the nanosecond timescale of the MD simulation. Structural and dynamical properties of the bilayer both with and without the transmembrane protein are reported.

The major transition state in folding need not involve the immobilization of side chains

During protein folding in which few, if any, definable kinetic intermediates are observable, the nature of the transition state is central to understanding the course of the reaction. Current experimental data does not distinguish the relative contributions of side chain immobilization and dehydration phenomena to the major rate-limiting transition state whereas this distinction is central to theoretical models that attempt to simulate the behavior of proteins during folding. Renaturation of the small proteinase inhibitor cystatin under oxidizing versus reducing conditions is the first experimental case in which these processes can be studied independently. Using this example, we show that sidechain immobilization occurs downstream of the major folding transition state. A consequence of this is the existence of states with disordered side chains, which are distinct from kinetic protein folding intermediates and which lie within the folded state free energy well.

Two possible conducting states of the influenza A virus M2 ion channel

Molecular dynamics simulations have been performed on protonated four-helix bundles based on the 25-residue Duff-Ashley transmembrane sequence of the M2 channel of the influenza A virus. Well-equilibrated tetrameric channels, with one, two and four of the H37 residues protonated, were investigated. The protonated peptide bundles were immersed in the octane portion of a phase-separated water/octane system, which provided a membrane-mimetic environment. The simulations suggest that there could be two conducting states of the M2 channel corresponding to tetramers containing one or two protonated histidines. The more open structure of the doubly protonated state suggests it would have the higher conductance.

Osteoblast-derived cells express functional glucose-dependent insulinotropic peptide receptors

Glucose-dependent insulinotropic peptide (GIP) is a 42-amino acid peptide synthesized and secreted from endocrine cells in the small intestine. The role of GIP in coupling nutrient intake and insulin secretion, the incretin effect, is well known. We report that GIP receptor messenger RNA and protein are present in normal bone and osteoblast-like cell lines, and that high affinity receptors for GIP can be demonstrated by [125I]GIP binding studies. When applied to osteoblast-like cells (SaOS2), GIP stimulated increases in cellular cAMP content and intracellular calcium, with both responses being dose dependent. Moreover, administration of GIP results in elevated expression of collagen type I messenger RNA as well as an increase in alkaline phosphatase activity. Both of these effects reflect anabolic actions of presumptive osteoblasts. These results provide the first evidence that GIP receptors are present in bone and osteoblast-like cells and that GIP modulates the function of these cells.

Expression of BRC repeats in breast cancer cells disrupts the BRCA2-Rad51 complex and leads to radiation hypersensitivity and loss of G(2)/M checkpoint control

BRCA2 is a breast tumor suppressor with a potential function in the cellular response to DNA damage. BRCA2 binds to Rad51 through its BRC repeats. In support of the biological significance of this interaction, we found that the complex of BRCA2 and Rad51 in breast cancer MCF-7 cells was diminished upon conditional expression of a wild-type, but not a mutated, BRC4 repeat using the tetracycline-inducible system. Cells expressing a wild-type BRC4 repeat showed hypersensitivity to gamma-irradiation, an inability to form Rad51 radiation-induced foci, and a failure of radiation-induced G(2)/M, but not G(1)/S, checkpoint control. These results strongly suggest that the interaction between BRCA2 and Rad51 mediated by BRC repeats is critical for the cellular response to DNA damage.

[The effects of lead poisoning on expression of nerve growth factor gene of submandibular gland in mice]

OBJECTIVE

To study the toxicity of lead poisoning to submandibular gland and its effects on nerve growth factor (NGF) gene expression in mice.

METHODS

An experimental model with lead poisoning was established and its histopathological changes in the submandibular gland of mice were observed under light and electronic microscopes. Effects of lead poisoning on expression of NGF mRNA in submandibular gland were analyzed quantitatively by human NGF DNA probe labelled with digoxin with in situ hybridization.

RESULTS

Body weight of the mice with experimental lead poisoning reduced, and their lead levels in blood and submandibular gland increased. Lobular atrophy, fibrous hypertrophy, angiectasis of the stroma and enlargement of lobule interstitial in mouse submandibular gland with lead poisoning could be found under light and electron microscopes. Their rough surfaced endoplasmic reticulum was extended and mitochondrion swollen. Graphic analysis showed that diameters of the secretory striate ducts and granular tubules decreased in the mice with lead poisoning. Results of in situ hybridization indicated that hybridized signals in the granular and secretory striate ducts and granular tubules reduced significantly, and NGF mRNA expression decreased.

CONCLUSION

Lead is toxic to the submandibular gland of mice and can affect their NGF gene expression.

Association of BRCA1 with the hRad50-hMre11-p95 complex and the DNA damage response

BRCA1 encodes a tumor suppressor that is mutated in familial breast and ovarian cancers. Here, it is shown that BRCA1 interacts in vitro and in vivo with hRad50, which forms a complex with hMre11 and p95/nibrin. Upon irradiation, BRCA1 was detected in discrete foci in the nucleus, which colocalize with hRad50. Formation of irradiation-induced foci positive for BRCA1, hRad50, hMre11, or p95 was dramatically reduced in HCC/1937 breast cancer cells carrying a homozygous mutation in BRCA1 but was restored by transfection of wild-type BRCA1. Ectopic expression of wild-type, but not mutated, BRCA1 in these cells rendered them less sensitive to the DNA damage agent, methyl methanesulfonate. These data suggest that BRCA1 is important for the cellular responses to DNA damage that are mediated by the hRad50-hMre11-p95 complex.

The Nijmegen breakage syndrome protein is essential for Mre11 phosphorylation upon DNA damage

The Nijmegen breakage syndrome (NBS), a chromosomal instability disorder, is characterized in part by cellular hypersensitivity to ionizing radiation. Repair of DNA double-strand breaks by radiation is dependent on a multifunctional complex containing Rad50, Mre11, and the NBS1 gene product, p95 (NBS protein, nibrin). The role of p95 in these repair processes is unknown. Here it is demonstrated that Mre11 is hyperphosphorylated in a cell cycle-independent manner in response to treatment of cells with genotoxic agents including gamma irradiation. This response is abrogated in two independently established NBS cell lines that have undetectable levels of the p95 protein. NBS cells are also deficient for radiation-induced nuclear foci containing Mre11, while those with Rad51 are unaffected. An analysis of the kinetic relationship between Mre11 phosphorylation and the appearance of its radiation-induced foci indicates that the former precedes the latter. Together, these data suggest that specific phosphorylation of Mre11 is induced by DNA damage, and p95 is essential in this process, perhaps by recruiting specific kinases.

Exploration of the structural features defining the conduction properties of a synthetic ion channel

The finite-difference Poisson-Boltzmann methodology was applied to a series of parallel, alpha-helical bundle models of the designed ion channel peptide Ac-(LSSLLSL)3-CONH2. This method is able to fully describe the current-voltage curves for this channel and quantitatively explains their cation selectivity and rectification. We examined a series of energy-minimized models representing different aggregation states, side-chain rotamers, and helical rotations, as well as an ensemble of structures from a molecular dynamics trajectory. Potential energies were computed for single, permeating K+ and Cl- ions at a series of positions along a central pathway through the models. A variable-electric-field Nernst-Planck electrodiffusion model was used, with two adjustable parameters representing the diffusion coefficients of K+ and Cl- to scale the individual ion current magnitudes. The ability of a given DelPhi potential profile to fit the experimental data depended strongly on the magnitude of the desolvation of the permeating ion. Below a pore radius of 3.8 A, the predicted profiles showed large energy barriers, and the experimental data could be fit only with unrealistically high values for the K+ and Cl- diffusion coefficients. For pore radii above 3.8 A, the desolvation energies were 2kT or less. The electrostatic calculations were sensitive to positioning of the Ser side chains, with the best fits associated with maximum exposure of the Ser side-chain hydroxyls to the pore. The backbone component was shown to be the major source of asymmetry in the DelPhi potential profiles. Only two of the energy-minimized structures were able to explain the experimental data, whereas an average of the dynamics structures gave excellent agreement with experimental results. Thus this method provides a promising approach to prediction of current-voltage curves from three-dimensional structures of ion channel proteins.

Development of endothelium-dependent relaxation in canine coronary collateral arteries

BACKGROUND

Little information exists regarding development of vasomotor control mechanisms during coronary collateral artery maturation. Therefore, we studied endothelium-dependent relaxation of canine collateral arteries isolated 2, 4, and 9 months after placement of an ameroid occluder around the proximal left circumflex coronary artery.

RESULTS

Collateral arteries isolated after 2 months exhibited markedly reduced endothelium-dependent relaxation in response to acetylcholine (ACh; 10(-10) to 10(-4) mol/L) and bradykinin (BK; 10(-11) to 10(-6) mol/L) compared with relaxation of noncollateral coronary arteries (P<0.01). In contrast, endothelium-independent relaxation of collateral arteries to nitroprusside was only slightly reduced compared with relaxation of noncollateral arteries (P<0.05). Endothelium-dependent relaxation of collateral arteries isolated after 4 and 9 months was increased significantly, to the extent that relaxation to ACh and BK was not significantly different between collateral and noncollateral arteries at these periods. Inhibition of nitric oxide synthesis with NT-nitro-L-arginine methyl ester (L-NAME; 100 micromol/L) markedly inhibited ACh-induced relaxation in all noncollateral arteries and in collateral arteries isolated after 9 months. However, neither L-NAME nor indomethacin (5 micromol/L) alone inhibited ACh-mediated relaxation of collateral arteries isolated after 4 months. ACh-induced relaxation of these collateral arteries was only inhibited when arteries were preconstricted with 30 mmol/L K+ and pretreated with L-NAME and indomethacin (ie, when synthesis/effects of nitric oxide, prostaglandins, and endothelium-derived hyperpolarizing factor were inhibited).

CONCLUSIONS

Development of endothelium-dependent relaxation in canine coronary collateral arteries is not complete after 2 months. After 4 months, endothelium-dependent relaxation of collateral arteries is similar to relaxation of noncollateral arteries, but the relaxation exhibits decreased dependence on synthesis of nitric oxide and increased involvement of prostaglandins and endothelium-derived hyperpolarizing factor(s). After 9 months of development, collateral arteries exhibit normal nitric oxide-dependent relaxation, similar to noncollateral arteries.

The M2 channel of influenza A virus: a molecular dynamics study

Molecular dynamics simulations have been performed on a tetramer of the 25-residue (SSDPLVVAASIIGILHLILWILDRL) synthetic peptide [1] which contains the transmembrane domain of the influenza A virus M2 coat protein. The peptide bundle was initially assembled as a parallel alpha-helix bundle in the octane portion of a phase separated water/octane system, which provided a membrane-mimetic environment. A 4-ns dynamics trajectory identified a left-handed coiled coil state of the neutral bundle, with a water filled funnel-like structural motif at the N-terminus involving the long hydrophobic sequence. The neck of the funnel begins at V27 and terminates at H37, which blocks the channel. The C-terminus is held together by inter-helix hydrogen bonds and contains water below H37. Solvation of the S23 and D24 residues, located at the rim of the funnel, appears to be important for stability of the structure. The calculated average tilt of the helices in the neutral bundle is 27 +/- 5 degrees, which agrees well with recent NMR data.

Simulation of the HIV-1 Vpu transmembrane domain as a pentameric bundle

The transmembrane domain of oligomeric protein Vpu encoded by HIV-1 has been studied by means of a molecular dynamics simulation. A pentameric bundle of unconstrained helices (residues 6-28 of Vpu) with a water filled pore was initially assembled in a membrane mimetic octane/water system. This system was simulated, using the CHARMm19 and OPLS united atom force fields with no constraints at a temperature of 300 K and a pressure of 1 atm. For these forcefields and the initial conditions tested, the oligomeric bundle expelled most of the pore water molecules. The resulting bundle and residual waters adopt a conical structural motif with some resemblance to a potassium channel.

Perturbation of TSG101 protein affects cell cycle progression

tsg101 was recently identified as a tumor susceptibility gene by functional inactivation of allelic loci in mouse 3T3 fibroblasts. Although previous studies suggested that homozygous intragenic deletion of TSG101 is rare in breast cancer cells and specimens, the neoplastic phenotype caused by tsg101 inactivation implicated that tsg101 may play a significant role in cell growth control. Here, we characterize mouse polyclonal and monoclonal antibodies that specifically recognize the TSG101 protein (molecular mass, 46 kDa) in whole-cell lysates by straight Western blot analysis. By indirect immunofluorescence staining, TSG101 was found to be localized in the cytoplasm throughout the entire cell cycle. However, the nuclear staining increases from G1 to S phase and becomes dominant in late S phase. TSG101 is mainly distributed surrounding the chromosomes during M phase. The expression level of TSG101 is not cell cycle dependent. It is possible that the relocalization of TSG101 from the cytoplasm into the nucleus may be relevant to its function. Microinjection of both polyclonal and monoclonal antibodies specific to TSG101 into cells during G1 or S phase results in cell cycle arrest. Furthermore, overexpression of TSG101 leads to cell death, suggesting that the appropriate amount of TSG101 is critical for cell cycle progression. Taken together, these results suggest that neoplastic transformation caused by TSG101 deficiency may result from bypassing of the cell cycle checkpoints.

Molecular dynamics study of the LS3 voltage-gated ion channel

Molecular dynamics calculations have been carried out on a model of the LS3 synthetic ion channel in a membrane mimetic environment. In the absence of an external electrostatic field, the LS3 channel, which consists of a bundle of six alpha-helices with sequence Ac-(LSSLLSL)3-CONH2, exhibits large structural fluctuations. However, in the presence of the field, the bundle adopts a well defined coiled-coil structure with an inner pore of water. The observed structural changes induced by the applied field are consistent with the proposed gating mechanism of the ion channel.

Molecular dynamics simulation of a synthetic ion channel

A molecular dynamics simulation has been performed on a synthetic membrane-spanning ion channel, consisting of four alpha-helical peptides, each of which is composed of the amino acids leucine (L) and serine (S), with the sequence Ac-(LSLLLSL)3-CONH2. This four-helix bundle has been shown experimentally to act as a proton-conducting channel in a membrane environment. In the present simulation, the channel was initially assembled as a parallel bundle in the octane portion of a phase-separated water/octane system, which provided a membrane-mimetic environment. An explicit reversible multiple-time-step integrator was used to generate a dynamical trajectory, a few nanoseconds in duration for this composite system on a parallel computer, under ambient conditions. After more than 1 ns, the four helices were found to adopt an associated dimer state with twofold symmetry, which evolved into a coiled-coil tetrameric structure with a left-handed twist. In the coiled-coil state, the polar serine side chains interact to form a layered structure with the core of the bundle filled with H2O. The dipoles of these H2O molecules tended to align opposite the net dipole of the peptide bundle. The calculated dipole relaxation function of the pore H2O molecules exhibits two reorientation times. One is approximately 3.2 ps, and the other is approximately 100 times longer. The diffusion coefficient of the pore H2O is about one-third of the bulk H2O value. The total dipole moment and the inertia tensor of the peptide bundle have been calculated and reveal slow (300 ps) collective oscillatory motions. Our results, which are based on a simple united atom force-field model, suggest that the function of this synthetic ion channel is likely inextricably coupled to its dynamical behavior.

[Studies on hydrolysis of anti-HRV IgY and its oral passive immunity effect to human rotavirus]

In this paper, hens of fine breed were immunized with human rotavirus (HRV), and the anti-HRV IgY was isolated and purified from their eggs collected daily. In addition, the resistance of anti-HRV IgY to hydrolysis of gastric juice and proteases in human digestive tract, the safety of IgY and the effectiveness of IgY in clinical use were observed as well. The results showed that anti-HRV IgY has a fairly good resistance to gastroinstestinal proteases. The safety of using anti-HRV IgY was affirmed by oral administration to mice of a solution of IgY. In clinical test the IgY has been proved to be anti-HRV and, therefore, effective against infections of infant diarrhea induced by HRV.

[Experimental study of skin expansion of the grafted free vascularized skin flap]

By using retro-auricular skin after skin expansion to reconstruct auricle, often-times, the retro-auricular skin could not be expanded because of certain reasons such as having burn scar. For this purpose, a new operative technique was designed. The experiment consisted of using 15 rabbits, on one side of the back, a free vascularized skin flap was obtained. Following the anastomosis of the vessels of the flap with that of the back the flap was sutured back in situ. Two weeks after the removal of the sutures, the grafted skin flap was expanded as usual. The routine skin expansion was carried out on the contralateral side as control. The volume of expansion, change of subcutaneous blood vessels, complications from operation, and histological observation were used to compare the results of skin expansion of the two sides. The result showed that there was no significant difference between the types of skin expansion. It was concluded the grafted free vascularized skin flap had no adverse effect on skin expansion.

Identification of cellular TSG101 protein in multiple human breast cancer cell lines

tsg101 was identified as a tumor susceptibility gene by homozygous functional inactivation of allelic loci in mouse 3T3 fibroblasts. The human homologue was mapped at chromosome 11p15.1-2 and found to have intragenic deletion in 7 of 15 breast cancer specimens. To further confirm the relevance of defects in this gene to breast cancer, antibodies specific for the putative gene product were prepared and used to identify cellular TSG101 protein. The antibodies recognized a 46-kDa protein in human retinoblastoma WERI-27 cells labeled with [35S]methionine. This protein was not detected with preimmune sera. In cell fractionation studies, the 46-kDa protein cofractionating with glutathione S-transferase was found mainly in the cytoplasm. Similarly, when cells were immunostained with anti-TSG101 antibodies, fluorescence was localized in the cytoplasm of most of the cells. A full-size 46-kDa TSG101 protein was detected in a panel of 10 breast cancer cell lines and 2 normal breast epithelial cell lines with the same antibodies. Consistently, the full-length TSG101 mRNA was also detected in these breast cells using reverse transcription-PCR. These results indicate that homozygous intragenic deletion of TSG101 is rare in breast cancer cells.

[Local administration of drug during tissue expansion]

In order to shorten the expansion time and reduce complications in tissue expansion, we developed a new method using local delivery of drug during tissue expansion. The procedure commenced with placing an implant syringe between the skin and the expander. While the skin was expanded, the drugs such as prednisolone and procaine were injected under the skin from the implant syringe. We have used the method in 23 cases and compared the results with the control group of 11 cases. It was found that the new method shortened the expansion time and reduced complications. The method had definite effect and the manipulation was simple and convenient. We conclude that the method is of value to assist tissue expansion and is worth employing routinely.

A clearer distinction between HIV-1 paired isolates from peripheral blood mononuclear cells of asymptomatic carriers with and without CD8+ T-cells at nef rather than env V3 loci

In asymptomatic carriers, the vast majority of human immunodeficiency virus type 1 (HIV-1) infection is non-productive whilst the clinical stage of disease is associated with significant virus expression. Virus-specific CD8+ T-cell functions are believed to play a major role in the generation of heterogeneous virus populations and in subsequent disease progression. Here, we prepared two types of HIV-1 isolate by culturing whole and CD8+ T cell-depleted peripheral blood mononuclear cells (PBMCs) from five asymptomatic carriers. The former is expected to be escape variant populations, whereas the latter would be mixed populations including the former viruses. The analyses of Nef and Env V3 sequence variations of viruses in a total of 77 and 44 DNA clones, respectively, allowed a direct comparison to be made of the differences between the paired isolates. Comparison of Nef sequences between the paired isolates showed them to be more distinct in two carriers with a relatively stable CD4/CD8 ratio (Nos 68 and 69), than in two other carriers with similar CD4/CD8 ratios (Nos 53 and 57), or in carrier No. 67, which had an extremely lower CD4/CD8 ratio. By contrast, a distinction between the paired isolates by use of the Env V3 sequences was only apparent in the latter three carriers. These results indicate that the predominant populations of HIV-1 in Nos 68 and 69 were sensitive to selective pressure from Nef-specific CD8+ T-cells, while those in Nos 53, 57, and 67 were sensitive to pressure from V3-specific CD8+ T-cells. It is noteworthy that Nos 53 and 57 progressed to an AIDS-related complex shortly and several years after this examination. These data suggest that HIV-1-induced pathogenesis is more strongly associated with the generation of variant nef alleles than with env V3 variants, and that these arise by CD8+ T-cell pressure.

Growth dominance of a revertant virus generated during in vitro serial passage of nef frameshift mutant of HIV-1

We prepared a series of nef mutant HIV-1 with a frameshift mutation at the Xho I site by up to 50 serial transfers into MT-4 cells. Here, we studied revertants. Immunofluorescence using an anti-Nef monoclonal antibody revealed that cells first became Nef antigen-positive at the 23rd passage. The percentage of Nef antigen-positive cells gradually increased and reached almost 100% by the 27th passage. The sequence of the provirus in the cells supported the generation of a revertant. This revertant mutated at the site immediately after the initially introduced frameshift mutation. This resulted in the substitution of only three amino acids and the insertion of two, which restored the proline-rich domain, a conserved region believed essential to viral replication, at the middle of Nef. Thus, the growth dominance of the revertant virus, compared with the original nef mutant, was directly demonstrated in vitro using serial passages consisting of mixed HIV-1 populations in a single cell.

Induction of apoptosis by protease-defective particle preparations of human immunodeficiency virus type 1 is specific to a subset of U937-derived subclones

Several recent reports support the hypothesis that apoptosis occurring in leukocytes of human immunodeficiency virus type 1 (HIV-1)-infected individuals is important in progression to AIDS. Specifically, apoptosis of uninfected bystander cells appears critical in the pathogenesis of disease. Here, we present evidence that protease-defective, gp120-containing HIV-1 (L-2) particle preparations specifically induce apoptosis in cells obtained from a subset of promonocytic U937-derived subclones. The rate of apoptosis induction was inversely correlated with the susceptibility of the U937 subclones to wild-type HIV-1 infection. Three types of apoptosis experiments were performed: DNA content analysis by flow cytometry, apoptotic nuclear degradation by fluorescent microscopy and DNA fragmentation analysis by agarose gel electrophoresis. Kinetic analysis revealed that there was a slower induction of apoptosis by L-2 particle preparations than with tumor necrosis factor (TNF)-alpha or anti-Fas antibody. However, there were no significant differences in the initial binding rates of L-2 particles as well as the binding of TNF-alpha or anti-Fas antibody to the U937 subclones. The basal level of protein kinase C activity was higher in high-type subclones compared with low-type subclones. These results suggest that U937 cells can be divided into at least two subpopulations, one that permits a productive HIV-1 infection but is not subjected to L-2 particle preparation-induced apoptosis, while the other poorly replicates HIV-1 and is subjected to L-2 mediated apoptosis, although at a slower rate than found with TNF-alpha or anti-Fas antibody.

Extracellular Nef protein regulates productive HIV-1 infection from latency

In HIV-1-infected asymptomatic carriers, the vast majority of infected cells in PBMCs are believed to be latently or nonproductively infected. We have isolated a subclone (MOLT-20-2) from an infected T cell line that expressed HIV-1 Ags at a very low level. However, viral Ag expression was markedly up-regulated by stimulation with either TNF-alpha, A23187, or PMA, indicating that the subclone might provide a suitable model of HIV-1 latency. Our previous studies have shown that the carboxyl-terminal region of the extracellular form of HIV-1 Nef played an important role in the interaction of infected cells with uninfected T cells, and could induce the cytostatic state. This suggested that Nef might contribute to intracellular signal transduction through an interaction with latently infected cells. We show in this study that stimulation of MOLT-20-2 with soluble Nef leads to HIV-1 activation from latency in a dose-dependent manner. Moreover, using a total of 14 overlapping Nef-related synthetic peptides, stimulatory activity was mapped to a discrete peptide (amino acid residues 132-147) that had the potential to activate latent HIV-1. This novel Nef function was confirmed by activation of virus production from the PBMCs of asymptomatic carriers. In addition, Nef-dependent HIV-1 activation from latency was also observed in another independently derived, latently infected cell line, U1, though not in cell line ACH-2. These results extend the significance of the Nef activity in vivo to the regulation of productive HIV-1 infection from latency, and define the regions of the protein involved.