Present situation in preventing and treating liver fibrosis with TCM drugs

Considerable evidences have shown that the mechanism of TCM drugs for preventing and treating liver fibrosis is very complicated. TCM treatment can not only inhibit viral replication, ameliorate inflammation and promote blood circulation in the liver, and enhance regeneration of the hepatic cells, but also inhibit HSC proliferation, intra- and extracellular secretion, decrease the secretion of collagen and promote its degradation and re-absorption. However, most of the animal models are only suitable for studies of acute hepatitis. Establishment of cell lines suitable for studies of fibrosis is still at its initial stage. What we expect is that comprehensive clinical studies in TCM treatment of liver fibrosis will be carried out and evaluation of each datum given, both of which are of importance.

Beta-chemokine induction of activation protein-1 and cyclic AMP responsive element activation in human myeloid cells

Chemokines effect leukocyte chemotaxis and activation through their binding to specific G protein-coupled receptors. Although early steps in chemokine signal transduction pathways have been characterized, there is relatively limited information available at the transcription factor level. To that end, we have examined the binding activity on activation protein-1 (AP-1) and cyclic AMP responsive element (CRE) target sequences in human THP-1 myeloid cells after treatment with the beta-chemokine macrophage inflammatory protein (MIP-1alpha). MIP-1alpha induced both AP-1 and CRE activation. Although inhibition of protein kinase C blocked the AP-1 activity induced by this chemokine, there was no decrease in CRE activation in the presence of a protein kinase A inhibitor. Using kinase assays, it appeared that mitogen-activated protein kinase pathways were involved in CRE activation. In addition, HIV-1 infection of THP-1 cells resulted in constitutive activation of AP-1 and CRE elements but no further response to MIP-1alpha treatment. These results suggest that beta-chemokines act via protein kinase C-dependent pathways and mitogen-activated protein kinase pathways to modulate the host transcriptional response in myeloid cells, and that this response is altered by HIV infection.

Cyclic core dendrimer as a new kind of vector for gene transfer into mammalian cells

Cyclic core dendritic polymer is a new type of synthetic polymers. The ability of generation 4 of the dendrimer with a core of 1,4,7,10-tetraazacyclododecane to function as an effective gene delivery vector was investigated. Results from fluorescence in situ hybridization (FISH) show that the pCH 110 plasmid DNA was transferred into human small intestine cancer metastatic ascites (HICMA) cells induced by this kind of dendrimer as a vector. The transferred LacZ, GFP and luciferase genes were highly expressed in the transfected HICMA, COS-7 and 293 cells. These studies demonstrate that the dendrimer can transfect mammalian cells in vitro which offers an alternatively efficient method for mammalian gene transfer.

[Prediction of prognosis of patients with multiple organ dysfunction syndrome by sepsis-related organ failure assessment]

OBJECTIVE

To describe the clinical properties of multiple organ dysfunction syndromB (MODS) with sepsis-related organ failure assessment (SOFA).

METHODS

A total of 366 MODS patients admitted to the 5 participating ICUs from 1990 to 1996 were included in this study. SOFA score and demographic data were retrospectively evaluated.

RESULTS

Total maximum SOFA score, delta SOFA and admission total SOFA score exhibited a good correlation with hospital mortality rate, with the area under the ROC curve of 0.819, 0.750 and 0.616, respectively. The SOFA score for patients without organ failure was 3.7 +/- 1.2, with a mortality rate of 21.7%, and the SOFA score for patients with failure of all 6 organs was 20.2 +/- 1.4, with a mortality rate of 77.8%. A maximum score was firstly reached for respiratory system (1.41 days after admission), and last for cardiovascular system (4.89 days). Logistic regression model revealed that the central nervous system was associated with the highest relative contribution (odds ratio 1.75) to hospital outcome, followed by renal (OR 1.42), cardiovascular (OR 1.38), coagulation (OR 1.34) and respiratory (OR 1.17) systems. No independent contribution was found for the hepatic score (OR 0.99).

CONCLUSION

Total maximum SOFA score and delta SOFA can be used to quantify the progress of MODS during ICU stay.

Elevated Egr-1 in human atherosclerotic cells transcriptionally represses the transforming growth factor-beta type II receptor

Atherosclerotic lesions may progress due to a "failure to die" by vascular repair cells. Egr-1, a zinc finger transcription factor, is elevated more than 5-fold in human carotid lesions relative to the adjacent tunica media. Lesion cells in vitro also express 2-3-fold higher Egr-1 mRNA and protein levels but express much lower levels of the transforming growth factor-beta (TGF-beta) Type II receptor (TbetaR-2) and are functionally resistant to the antiproliferative effects of TGF-beta. Lesion cells fail to express a TbetaR-2 promoter/chloramphenicol acetyltransferase (CAT) construct but overexpress an Egr-1-inducible platelet-derived growth factor-A promoter/CAT construct. Transfection of Egr-1 cDNA represses TbetaR-2/CAT constructs but induces PDGF-A/CAT. Egr-1 transfection reduces the levels of TbetaR-2 and confers resistance to the antiproliferative effect of TGF-beta1. Egr-1 can interact directly with both the -143 Sp1 site and the positive regulatory element 2 (PRE2) (ERT/ets) region of the TbetaR-2 promoter. Thus, although activating a family of stress-responsive genes, Egr-1 also transcriptionally represses one of the major inhibitory pathways that restrains vascular repair.

Recurrent chromosome changes in 62 primary gastric carcinomas detected by comparative genomic hybridization

Comparative genomic hybridization (CGH) has been applied to detect recurrent chromosome alterations in 62 primary gastric carcinomas. Several nonrandom chromosomal changes, including gains of 8q (31 cases, 50%), 20q (29 cases, 47%) with a minimum gain region at 20q11. 2-q12, 13q (21 cases, 34%) with a minimum gain region at 13q22, and 3q (19 cases, 31%) were commonly observed. The regions most frequently lost included: 19p (23 cases, 37%), 17p (21 cases, 33%), and 1p (14 cases, 23%). High copy number gain (DNA sequence amplification) was detected in 6 cases. Amplification of 8q23-q24.2 and 20q11.2-q12 were observed in 3 cases. Gain of 20q and loss of 19p were confirmed by fluorescence in situ hybridization using corresponding bacterial artificial chromosomes (BAC) clones from those regions. The gain and loss of chromosomal regions identified in this study provide candidate regions involved in gastric tumorigenesis.

[Study on pathogenicity of sputum from cavity of sputum negative patients with pulmonary tuberculosis after short course chemotherapy]

OBJECTIVE

To find out whether or not the sputa of pulmonary tuberculosis(PTB) patients with cavitation but sputum negative have pathogenicity after short course chemotherapy.

METHODS

Guinea pigs were inoculated with sputa of PTB patients who were with cavitation but sputum negative after having finished short course chemotherapy. Then their body weight, enlargement of local lymph nodes and other ordinary symptom were observed. Six weeks later, pathological changes of TB in the internal organs were examined by dissecting these guinea pigs. Culture and drug resistance test of tubercle bacillus were also conducted. All of which were with negative and positive controls.

RESULTS

Of the 63 cases included, 3(5%) patients' sputa resulted in tuberculous nodulation varying in amount in lung, liver and spleen of these guinea pigs, and the culture for tubercle bacillus of these sputa was positive too.

CONCLUSIONS

5% of sputum collected from PTB patients with cavitation but sputum negative still show pathogenicity after short course chemotherapy. For the cases with drug-resistant PTB and slow sputum negative conversion, the treatment should be prolonged and tubercle bacilli in their sputa should be monitored.

Right ventricular function of patients with septic shock: clinical significance

OBJECTIVE

To understand the effect of right ventricular dysfunction on circulatory supportive therapy in patients with septic shock.

METHODS

25 patients with septic shock who were admitted consecutively to the intensive care unit (ICU) of Peking Union Medical College Hospital were observed prospectively. Hemodynamic profile of the left side and right side heart was monitored with right ventricular ejection fraction catheter and transthoracic echocardiography. Intramucosal pH (pHi) and oxygen delivery were also monitored to illustrate any relation with patient outcome.

RESULTS

Stroke volume index (SVI) and right ventricular ejection fraction (RVEF) were significantly higher in survivors than in nonsurvivors (P < 0.01 and < 0.05, respectively). The pulmonary vascular resistance index (PVRI) was significantly lower in survivors (P < 0.01). At the onset of shock, the left ventricular end-diastolic volume index (LVEDVI) of both groups was very low, and steadily increased in survivors but not in nonsurvivors. Left ventricular ejection fraction (LVEF) and systemic vascular resistance index (SVRI) decreased during treatment, which were not different in both groups. Right ventricular end-diastolic volume index (RVEDVI) increased in both survivors and nonsurvivors. Oxygen delivery of nonsurvivors was significantly lower than that of survivors. LVEDVI and RVEF were correlated with SVI in both survivors and nonsurvivors.

CONCLUSIONS

The impairment of right heart function may be more severe than that of left heart function in the patients with early septic shock. "Right heart priority" must be seriously considered in supportive treatment of patients with septic shock. The present treatment of septic shock has significant limitations, and even aggravates the existing cardiac dysfunction.

High-level expression of Egr-1 and Egr-1-inducible genes in mouse and human atherosclerosis

To understand the mRNA transcript profile in the human atherosclerotic lesion, RNA was prepared from the fibrous cap versus adjacent media of 13 patients undergoing carotid endarterectomy. cDNA expression arrays bearing 588 known genes indicated that lesions express unexpectedly high levels of the early growth response gene, Egr-1 (NGFI-A), a zinc-finger transcription factor that modulates a cluster of stress-responsive genes including PDGF and TGF-beta. Expression of Egr-1 was an average of 5-fold higher in the lesion than in the adjacent media, a result confirmed by RT-PCR, and many Egr-1-inducible genes were also strongly elevated in the lesion. Time-course analyses revealed that Egr-1 was not induced ex vivo. Immunocytochemistry indicated that Egr-1 was expressed prominently in the smooth muscle-actin positive cells, particularly in areas of macrophage infiltration, and in other cell types, including endothelial cells. Induction of atherosclerosis in LDL receptor-null mice by feeding them a high-fat diet resulted in a progressive increase in Egr-1 expression in the aorta. Thus, induction of Egr-1 by atherogenic factors may be a key step in coordinating the cellular events that result in vascular lesions.

[Clinical observation on ganrening granule in treating common cold]

OBJECTIVE

To explore the therapeutic effect of Ganrening Granule (GRN) in treating common cold.

METHODS

Four hundred cases of common cold were randomly divided into three groups, the GRN group (160 Patients), the control group (100 Patients) and the opened group (140 Patients). The changes in symptoms and body temperature of patients were observed before and after treatment by single blind method, and the therapeutic effect was assessed according to the "Guideline of Clinical Research of TCM New Drugs".

RESULTS

The markedly effective rate and total effective rate of the GRN group were 81.25% and 96.88% respectively, while those of the control group were 44.44% and 88.00% respectively. The difference between the two groups was significant (P < 0.01). GRN showed significant effect in subsiding fever.

CONCLUSION

GRN has good effect in treating common cold (Syndrome of both Weifen and Qifen). No adverse effect was found in the clinical trial.

Expression of membrane type 1-matrix metalloproteinase in laryngeal carcinoma

Membrane type 1-matrix metalloproteinase (MT1-MMP) is a member of the recently identified unique membrane-type subgroup in the matrix metalloproteinase (MMP) family. MT1-MMP has proteolytic activity against components of the extracellular matrix and activates progelatinase A (MMP-2) at the cell surface. In this study, we analyzed the expression of MT1-MMP mRNA in 45 cases of laryngeal carcinoma by RT-PCR and investigated the relationship between MT1-MMP expression and survival in 18 cases. The result showed that the expression of MT1-MMP mRNA was higher in tumor tissue than in corresponding normal tissue. The tumoral expression in clinical stage III was higher than in stage II. The tumoral expression level of MT1-MMP mRNA in patients with lymph node metastasis was signigicantly higher than those with negative lymph nodes. The patients with high expression level showed significantly poorer 5 year survival than those with low expression level. Collectively, our findings suggest that the high level of MT1-MMP expression is closely related to the invasion and metastasis of laryngeal carcinoma, and indicates poorer prognosis.

The expression of TGF-beta receptors in human atherosclerosis: evidence for acquired resistance to apoptosis due to receptor imbalance

The degree of cellularity in vascular lesions is determined by the balance between the migration and proliferation of cells relative to their rate of egress and apoptosis. Transforming growth factor-beta(1) can act as a potent antiproliferative and apoptotic factor for proliferating vascular cells. Our laboratory has previously identified cells cultured from human vascular lesions that are resistant to the antiproliferative effect of TGF-beta(1) due to an acquired mutation in the Type II receptor for TGF-beta(1). In the present studies, the expression of the Type I and II receptors in coronary and carotid atherosclerotic lesions was analysed by immunostaining, RT-PCR, and in situ RT-PCR. Levels of the Type I and Type II receptors varied widely within lesions, with the highest levels in the fibrous cap and at discrete foci within the lesion. Regions of smooth muscle-like cells (SMC) were commonly found that were Type I positive but Type II receptor negative. In 43 cell lines cultured from 126 human lesions, 84% of the lesion-derived cell (LDC) cultures exhibited functional resistance to the antiproliferative effect of TGF-beta(1). This resistance was conferred against TGF-beta(1), TGF-beta(2), and TGF- beta(3), but not interferon-gamma or mimosine. While normal SMC exhibited a four-fold increase in the rate of apoptosis after TGF- beta(1) treatment, most LDC were resistant to apoptosis in response to TGF-beta(1). Resistant cells exhibited selective loss of Type II receptor expression, and retroviral transfection of Type II receptor cDNA partially corrected the functional deficit. Thus, resistance to apoptosis may lead to the slow proliferation of resistant cell subsets, thereby contributing to the progression of atherosclerotic and restenotic lesions.

CD4 receptor-dependent entry of human immunodeficiency virus type-1 env-pseudotypes into CCR5-, CCR3-, and CXCR4-expressing human alveolar macrophages is preferentially mediated by the CCR5 coreceptor

Alveolar macrophages (AM) are important host-defense cells and targets of human immunodeficiency virus type 1 (HIV-1) infection. However, the receptors mediating HIV-1 entry into AM are not completely characterized. We observed that, in addition to CD4 receptors, AM from healthy adults expressed low levels of CCR5, CCR3, and CXCR4 chemokine receptors by flow cytometry, and specific messenger RNA was detected for all three receptors by reverse transcriptase/polymerase chain reaction. The macrophage monocytotropic (M-tropic; YU2) and dual-tropic (89.6) HIV-1 env-pseudotypes entered AM efficiently, as expected given CCR3 and CCR5 expression. However, the T-lymphocytotropic (T-tropic; HXB2) pseudotype did not enter AM despite expression of the appropriate chemokine coreceptor CXCR4. Incubation of AM with regulated on activation, normal T cells expressed and secreted (RANTES) significantly impaired entry of the M-tropic (YU2) HIV-1 pseudotype, whereas SDF-1beta or eotaxin did not impair entry. The entry of simian immunodeficiency virus (SIV) pbj1.9 env-pseudotype into AM was not blocked by RANTES, SDF-1beta, or eotaxin. The competence of these chemokine receptors for virus entry was confirmed in Cf2Th canine thymocytes cotransfected with the human CD4 and chemokine receptors. Entry of the M-tropic (YU2) HIV-1 pseudotype was shown to be mediated by either CCR3 or CCR5, the T-tropic (HXB2) HIV-1 pseudotype by CXCR4, and the dual-tropic (89.6) HIV-1 or the SIVpbj1. 9 pseudotype by CCR5, CCR3, or CXCR4. Our data indicate that the mechanisms for HIV-1 entry are both receptor-specific and cell type-specific, and that chemokine receptor expression on AM does not fully explain cell susceptibility to different virus isolates.

Glucocorticoid resistance caused by reduced expression of the glucocorticoid receptor in cells from human vascular lesions

Mechanisms that control the balance between cell proliferation and death are important in the development of vascular lesions. Rat primary smooth muscle cells were 80% inhibited by low microgram doses of hydrocortisone (HC) and 50% inhibited by nanogram concentrations of transforming growth factor-beta1 (TGF-beta1), although some lines acquired resistance in late passage. However, comparable doses of HC, or TGF-beta1, failed to inhibit most human lesion-derived cell (LDC) lines. In sensitive LDC, HC (10 microg/mL) inhibited proliferation by up to 50%, with obvious apoptosis in some lines, and TGF-beta1 inhibited proliferation by more than 90%. Collagen production, as measured by [3H]proline incorporation or RIA for type III pro-collagen, was either unaffected or increased in the LDCs by HC. These divergent responses between LDC lines were partially explained by the absence of the glucocorticoid receptor (GR) and heat shock protein 90 mRNA in 10 of 12 LDC lines, but the presence of the mineralocorticoid receptor and 11beta-hydroxysteroid dehydrogenase type II. Western blot analysis confirmed the absence of the GR protein in cells lacking GR mRNA. Immunohistochemistry of human carotid lesions showed high levels of GR in the tunica media, but large areas lacking GR in the fibrous lesion. Considering the absence of the GR in most lines, the effects of HC may be elicited through the mineralocorticoid receptor. Functional resistance to the antiproliferative and antifibrotic effects of HC may contribute to excessive wound repair in atherosclerosis and restenosis.

Recombinant adeno-associated virus-based vectors provide short-term rather than long-term transduction of primitive hematopoietic stem cells

Bone marrow stem cells collected from B6-Gpi-1a mice pretreated with 5-fluorouracil were incubated for 2 h at 37 degrees C in the presence of the recombinant adenovirus-associated virus-based vector (rAAV) SSV9. As measured in vitro immediately following transduction, SSV9 was found to be effective in transducing the primitive cobble-stone-area-forming cell (CAFC)-35 subset (60% transduction efficiency). However, this did not predict long-term expression as the presence of the transgene could not be detected six months after transplantation of 1-2 x 106 transduced bone marrow stem cells into lethally irradiated recipients. CAFC analysis of bone marrow cells and Southern blot analysis of bone marrow and spleen cells were negative, and polymerase chain reaction analysis showed less than 0.1% transduction in bone marrow cells. Therefore, based on our study we conclude that rAAV transiently transduces hematopoietic stem cells but fails to integrate into the genome, leading to the loss of the reporter gene within the first six months after transplantation in vivo.

In vitro release of 5-fluorouracil with cyclic core dendritic polymer

This paper describes the first synthesis of a series of dendritic polymers with a core of 1,4,7,10-tetraazacyclododecane. This core was allowed to react with methyl acrylate through a Michael addition and was then amidated with ethylenediamine. Repeating the two steps led to controlled molecular weight increasing and branching on the molecular level and produced four direction poly(amide-amine) dendrimers. We successfully synthesized dendrimers from generation 0. 5 to generation 5.5. Each generation was analyzed by Fourier- transform infrared (FT-IR) spectroscopy, 1H NMR and elemental analysis. Titrimetry was also used to determine the number of -NH2 of each full generation (2.0, 3.0, 4.0, 5.0). SEC (size exclusion chromatography) was performed to test the purity of G-3.0, G-4.0 and G-5.0. Parts of the outer layer -NH2 groups of the dendrimers generation 4 and generation 5 were acylated by acetic anhydride. The solubility in water of the dendrimer was thus greatly enhanced. The acetylated dendrimers were then reacted with 1-bromoacetyl-5-fluorouracil to form dendrimer-5FU conjugates. Hydrolysis of the conjugates in a phosphate buffer solution (pH 7.4) at 37 degreesC will release free 5FU. Different generation of dendrimer-5FU conjugates exert marking influence on the amount of 5FU released. The dendritic polymer seems to be a promising carrier for the controlled release of antitumor drugs.

[Analysis of critically ill patients with bacteremia]

OBJECTIVE

To study the epidemiology of bacteremia of critically ill patients and the mortality associated with bacteremia and risk factors for death in an intensive care unit.

METHOD

75 patients with 116 episodes of bacteremia were retrospectively studied.

RESULTS

The mortality rate of the patients was 43%. Staphylococci (29%), Enterococci (12%), Class I inducible beta-lactamase-producing Enterobacter (12%), extensive spectrum beta-lactamase-producing Enterobacter (10%) were the most common pathogens, among which gram-positive organisms constitute a major part. The most commonly affected organs were respiratory (77%), hepatic (53%), circulatory (53%), gastrointestinal (50%), renal (47%), central nervous (36%), and hemopoietic systems (27%). Multiple organ failure accounted for 76%. Univariate analysis revealed that the severity of underlying illness, multiple organ failure (MOF), septic shock, hepatic failure, renal failure and infection focus were the risk factors for in-hospital death (P < 0.05). Cox proportional hazard model analysis suggested central nervous system failure, septic shock, hemopoietic failure, hepatic failure and respiratory manipulation significantly affected the survival time of patients with bacteremia (P < 0.05).

CONCLUSION

Gram-positive organisms are major pathogens of bacteremia in critically ill patients. Antibiotic therapy can not prevent the occurence of bacteremia, nor can it improve the prognosis.

Recombinant adeno-associated virus vector: use for transgene expression and anterograde tract tracing in the CNS

We used a recombinant adeno-associated virus vector (AAV) to deliver a foreign gene, green fluorescent protein (GFP), into mature neurons in adult rat CNS in vivo. Microinjections of AAV as small as 50 nl transduced hundreds of neurons at the injection site. There was virtually no retrograde transport as fewer than one neuron per brain was found distant from the injection site that exhibited GFP immunoreactivity. The gene product, GFP, filled the entire neuronal cytoplasmic compartment; GFP immunoreactivity was robust in cell bodies, axons, and nerve terminals. There was no tissue damage at the injection sites or pathogenicity indicated by changes in astrocytic or microglial markers. There was no inflammatory response as judged by leukocytic invasion. Gene expression in transduced cells was robust and apparently permanent: there was no evidence of phenotypic reversion up to 12 weeks following infection. AAV is an excellent vector for introducing foreign genes into mature CNS neurons. Not only might it be an ideal vehicle for gene therapy, but also the GFP-containing AAV presents a new strategy for tracing long axonal pathways in the CNS, which is difficult with current tracers (PHAL, biotinylated dextrans).

[Catalytic spectrophotometric determination of trace manganese in theragran-M with Mn (II)-KIO4-NTA-coomassie brilliant blue G250]

A new indicator reaction is developed on the basis of manganese catalyzed oxidation of coomassie brilliant blue G250 by potassium periodate with nitrilotriaetic acid as an activator. The detection limit for manganese is 6.76 x 10(-8) g/L. The linear range of determination is 0.02-0.30 microgram/25 mL.

[Clinical study of physiologic work of breathing as a weaning parameter in mechanically ventilated patients]

OBJECTIVE

To evaluate the physiologic work of breathing (WOBphy) as a predicting Parameter of weaning and extubation.

METHODS

WOBphy was obtained by the patient's work of breathing (WOBt), minuting the imposed work of breathing (WOBimp). In weaning trial, if the patients could not meet predefined extubation criteria, but WOBphy < 0.70 J/L, the patients were also extubated immediately.

RESULTS

In a group of 28 patients who met the predefined criteria (group 1), 27 patients were successfully extubated. In another group of 13 patients who could not meet the criteria, but WOBphy < 0.70 J/L (group 2), extubation was successful in 12 patients. WOBt and WOBimp were significantly higher in group 2 (1.37 +/- 0.50 and 0.82 +/- 0.37 J/L) than group 1 (0.96 +/- 0.38 and 0.55 +/- 0.27 J/L, P < 0.05), while WOBphy was higher in group 2, but did not reach statistical significance.

CONCLUSIONS

WOBphy < 0.70 J/L may be safe as the weaning and extubation criterion and enables earlier extubation.

Genomic instability in the type II TGF-beta1 receptor gene in atherosclerotic and restenotic vascular cells

Cells proliferating from human atherosclerotic lesions are resistant to the antiproliferative effect of TGF-beta1, a key factor in wound repair. DNA from human atherosclerotic and restenotic lesions was used to test the hypothesis that microsatellite instability leads to specific loss of the Type II receptor for TGF-beta1 (TbetaR-II), causing acquired resistance to TGF-beta1. High fidelity PCR and restriction analysis was adapted to analyze deletions in an A10 microsatellite within TbetaR-II. DNA from lesions, and cells grown from lesions, showed acquired 1 and 2 bp deletions in TbetaR-II, while microsatellites in the hMSH3 and hMSH6 genes, and hypermutable regions of p53 were unaffected. Sequencing confirmed that these deletions occurred principally in the replication error-prone A10 microsatellite region, though nonmicrosatellite mutations were observed. The mutations could be identified within specific patches of the lesion, while the surrounding tissue, or unaffected arteries, exhibited the wild-type genotype. This microsatellite deletion causes frameshift loss of receptor function, and thus, resistance to the antiproliferative and apoptotic effects of TGF-beta1. We propose that microsatellite instability in TbetaR-II disables growth inhibitory pathways, allowing monoclonal selection of a disease-prone cell type within some vascular lesions.

[Primary study on the sensitivity of cytokinesis blocked micronucleus assay in CHL cells]

Studies were performed to determine the cytochalasin B induced binucleated cell percentage influenced by clastogens and aneuploidgens and to compare the efficacy of cytokinesis blocked binucleated cells for scoring micronuclei with that of the conventional mononucleated method following the treatment with mitomycin C, methyl methanesulforate, colchicin and chloral hydrate. The results showed that mitomycin C decreased the binucleated cell percentage induced by cytochalasin B, whereas colchicin increased the frequencies of binucleated cells. The frequencies of micronuclei in binucleated cells were not significantly higher than those in the conventional mononucleated cells. The results suggest that cytokinesis blocked method is not more sensitive than the conventional method for scoring micronuclei. The factors that may influence the cytokinesis blocked micronucleus assay have been discussed.

[Recombinant AAV-LMP-induced LMP specific cytotoxic response to autologous lymphoblastoid cell lines tranformed by Epstein-Barr virus]

Epstein-Barr virus is believed to be controlled in normal host by virus specific cytotoxic T lymphocytes (CTL). Although unable to eliminate EBV from the body, CTL seems to be essential in control of latently infected cells. Infusion of autologous EBV specific CTL, which can be produced in laboratory by separating lymphocytes from patients and stimulating them with EBV antigen, will provide an effective method of preventing and treating EBV-related diseases. We inserted the LMP gene of EB virus into an AAV vector pACP and packed it in Ad2 infected 293 cells by co-transfecting with plasmid Ad8, which produced the recombinant virus rAAV-LMP. The recombinant virus was used to infect stimulating cells and LMP antigen was expressed on the surface of these cells. Then the stimulating cells were irradiated and co-cultured with T lymphocytes. The EBV specific CTLs were obtained. The target cells were autologous LCLs from EBV-transformed B lymphocytes. The CTL activity was assayed by BLT activity method. The result indicated that all the four CTL strains could recognize and kill their target cells. This study has laid the technical basis for us to prevent and treat nasopharyngeal carcinoma in China with molecular biological methods.

Experimental studies on extremely low frequency pulsed magnetic field inhibiting sarcoma and enhancing cellular immune functions

The previous observation with an electron microscope showed that extremely low frequency (ELF) pulsed magnetic field (PMF) (with the maximum intensity of 0.6-2.0 T, gradient of 10-100 T*M(-1), pulse width of 20-200 ms and frequency of 0.16-1.34 Hz) inhibited the growth of S-180 sarcoma in mice and enhanced the ability of immune cell's dissolving sarcoma cells. In this study, the DNA contents of nuclei were assayed by using Faulgen Staining method. With an electron microscope and cell stereoscopy technology it was observed that magnetic field affected the sarcoma cell 's metabolism, lowered its malignancy, and restrained its rapid and heteromorphic growth. The magnetic field enhanced the cellular immune ability and the reaction of lymphocytes and plasma. Since ELF pulsed magnetic fields can inhibit the growth of sarcomas and enhance the cellular immune ability, it is possible to use it as a new method to treat cancer.

[Prospective study of central venous catheter-related sepsis in critically ill patients]

To evaluate the incidence of central venous catheter-related sepsis (CRS) in critically ill patients, we performed a prospective study of the central venous catheters (CVCs) in ICU of the Peking Union Medical College Hospital from Jan. 1995 to March 1996. Of 151 CVCs, 13 (8.6%) had CRS, with an incidence of 16.7 episodes per 1000 catheter-days. Presence of infectious focus at catheterization, catheter insertion site, duration of catheterization, and the decrease of body temperature after catheter removal correlated with definite CRS, while difficulty of insertion, body temperature at catheter removal, as well as the decrease of body temperature after catheter removal correlated well with no CRS. The study showed that CRS is a serious problem in critically ill patients. Careful manipulation of CVCs is a major determinant in reducing the incidence of CRS.

[Clinical study of systemic inflammatory response syndrome and multiple organ dysfunction syndrome in critically patients]

We defined the epidemiology of systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS) in critically ill patients, and evaluated the procession from SIRS to MODS and the therapeutic strategies. 230 patients were studied prospectively until discharge or death. On admission, the morbidity rate of SIRS was 71.3%. The mortality rate of the patients with SIRS was 18.9%. MODS was developed in 65 patients (28.3%), and 33 patients dided (50.8%). In SIRS patients with non-infectious SIRS, sepsis and septic shock, the morbidity rates of MODS were 22.8%, 61.1% and 85.7%, and the mortality rates were 11.4%, 30.6% and 50.0% respectively. The outcome of critically ill patients may be improved if SIRS is early diagnosed and the body inflammatory response is reglulated properly.

Potent inhibition of human immunodeficiency virus type 1 in primary T cells and alveolar macrophages by a combination anti-Rev strategy delivered in an adeno-associated virus vector

The rate of viral replication appears to play a pivotal role in human immunodeficiency virus type 1 (HIV-1) pathogenesis and disease progression as it outstrips the capacity of the immune system to respond. Important cellular sites for HIV-1 production include T lymphocytes and tissue macrophages. Antiviral strategies, including newer treatment modalities such as gene therapy of HIV-1-susceptible cell populations, must be capable of engendering durable inhibitory effects to HIV-1 replication in both of these primary cell types in order to be effective. Among the potential genetic targets for intervention in the HIV-1 life cycle, the Rev regulatory system, consisting of Rev and its binding site, the Rev-responsive element (RRE), stands out as particularly attractive. Rev is essential for maintaining the stability of the viral genomic RNA as well as viral mRNAs encoding key structural and regulatory proteins. Moreover, it exhibits favorable threshold kinetics, in that Rev concentrations must rise above a critical level to exert their effect. To disable Rev function, primary T cells or macrophages were transduced with anti-Rev single-chain immunoglobulin (SFv) or RRE decoy genes either singly or in combination by employing adeno-associated virus vectors and then challenged with HIV-1. By directing both a protein and a nucleic acid against the normal interaction between Rev and the RRE, this genetic antiviral strategy effectively inhibited infection by either clinical or laboratory virus isolates. These results provide a framework for novel interventions to reduce virus production in the infected host.

[Relationship between nasal airflow sensation and nasal patency]

The relationship between nasal airflow sensation and nasal patency was evaluated by means of visual analogue test and anterior rhinomanometry. It was demonstrated that there is no significant correlation between the subjective sensation of nasal airflow and objective assessment of nasal airflow resistance. The site responsible for sensing airflow is located in the nasal vestibule. The volatile agents used in traditional Chinese medicine for nasal obstruction, such as camphor and menthol, could only improve the nasal sensation of airflow without alteration of nasal airway resistance. Our results suggested that the nasal sensation of airflow could not reflect real patency completely. Therefore, assessment of subjective sensation of airflow and measurement of nasal airway resistance combined must be used in the diagnosis and treatment of nasally obstructed patients.

[The effects of vibratory acoustic stimulation on fetal heart rate and body movement of normal fetuses at different gestational ages]

OBJECTIVE

To study the effects of vibratory acoustic stimulation (VAS) on fetal heart rate (FHR) and fetal movement (FM) of normal fetu at different gestational ages.

METHOD

435 normal second and third-trimester pregnancies were studied using real time ultrasonography. FHR baseline was recorded. Then a five-second VAS was given and FM and (or) FHR was observed. The results of vibroacoustic stimulation testing (VAS-T), sound-provoked fetal movement (SPFM) and the amplitude of FHR acceleration were evaluated.

RESULTS

(1) The fetus started to response to VAS from the 24th gestational week, but most could not reach the diagnostic criteria of VAS-T. The responses of FM were normal. (2) From 28 week on, 90% of the fetu showed marked FM and acceleration of FHR after VAS. Over 98% of the term babies were reactive. (3) The detective rates of SPFM appeared significantly earlier than that of VAS-T.

CONCLUSION

It suggested that the development of fetal nervous system was matured at 28 weeks, and the development of motor nerves was earlier than that of the autonomic nerves.

[Quantitative observation of expression of proliferation cell nuclear antigen in nasopharyngeal carcinoma]

Eighty-two cases of nasopharyngeal squamous cell carcinoma and twenty-five cases of nasopharyngitis were studied by means of LAS-SP immunohistochemical method with monoclonal anti-PCNA antibody and using image pattern analysis technique; correlation analysis was performed on expression of PCNA and five-year survival rate. It was shown: 1. The cell proliferative index and pathological grading of NPC were positively correlated, and the cell proliferative index and five-year survival rate negatively correlated. 2. PCNA expression level and pathological grading of NPC were positively correlated, and PCNA expression levels and five years survival rate negatively correlated in all pathological gradings of NPC except the vesicular nucleus cell carcinoma. The results indicate that PCNA affects proliferation activity of NPC and there are bright prospects for their application in the clinic. Expression of PCNA may also become a good indicator of the prognosis of NPC and the choice of treatment.

Identification of HIV-1 determinants for replication in vivo

Pathogenic organisms are frequently attenuated after long-term culture in vitro. The mechanisms of the attenuation process are not clear, but probably involve mutations of functions required for replication and pathogenicity in vivo. To identify these functions, a direct comparison must be made between attenuated genomes and those that remain pathogenic in vivo. In this study, we used the heterochimeric SCID-hu Thy/Liv mouse as an in vivo model to define human immunodeficiency virus type 1 (HIV-1) determinants which are uniquely required for replication in vivo. The Lai/IIIB isolate and its associated infectious molecular clones (e.g., HXB2) were found to infect T cell lines but failed to replicate in the SCID-hu Thy/Liv model. When a lab worker was accidentally infected by Lai/IIIB, however, HIV-1 was isolated only from infection of primary PBMC, and not from infection of T cell lines. We hypothesized that the lab worker was exposed to a heterogeneous viral stock which had been attenuated by passage in immortalized T cell lines. Either a rare family member from this stock was selected for in vivo replication or, alternatively, an attenuated genotype dominant in vitro may have reverted to become more infectious in vivo. To address this hypothesis, we have used the SCID-hu Thy/Liv model to study the replication of HXB2 and of HXB2 recombinant viruses with HIV-1 fragments isolated from the infected lab worker. HXB2 showed no or very low levels of replication in the Thy/Liv organ. Replacement of its subgenomic fragment encoding the envelope gene with a corresponding fragment from the lab worker isolate generated a recombinant virus (HXB2/LW) which replicated actively in SCID-hu mice. The NEF mutation in the HXB2 genome is still present in HXB2/LW. Thus, the LW sequences encode HIV-1 determinants which enhance HIV replication in vivo in a NEF-independent mechanism. The specific determinants have been mapped to the V1-V3 regions of the HIV-1 genome. Six unique mutations in the V3 loop region of HXB2/LW have been identified which contribute to the increased replication in vivo.

Effects of dexamethasone, ibuprofen, and ligustrazini on lipopolysaccharides-induced tumor necrosis factor alpha production

AIM

To study the influence of dexamethasone (Dex), ibuprofen (Ibu), and ligustrazini (Lig) on lipopolysaccharides (LPS)-induced tumor necrosis factor alpha (TNF alpha) gene expression (both mRNA and protein).

METHODS

TNF alpha in supernatants of human whole blood was measured by ELISA; The TNF alpha mRNA was assessed by slot blot analysis.

RESULTS

LPS-induced TNF alpha production was in a dose-dependent manner. TNF alpha levels in the whole blood increased markedly at 3 h and peaked at 6 h. The induction of TNF alpha mRNA was very rapid, peaking at 2 h after LPS challenge. Dex exerted inhibitory effects on TNF alpha production in a dose-dependent manner. Ibu and Lig had 2-phase effects on TNF alpha release.

CONCLUSION

Dex, Ibu, and Lig affected TNF alpha gene expression, so they may be new approaches of anti-TNF alpha for treatment of sepsis.

[The relationship of non-Hodgkin's lymphoma with P16 protein expression]

The expression of P16 protein was examined in 45 cases of non-Hodgkin's lymphoma (NHL), 4 cases of reactive hyperplasia of lymph node (RHLN) and 6 cases of normal spleen with immunohistochemical staining. Positive reaction of P16 protein was observed in some lymphocytes of RHLN and splenic nodule and around splenic sinus. The positive rate of P16 protein expression in NHL was 37.8% (17/45). The positive rates of P16 protein expression for the low intermadiate- and high-grade malignancy groups were 66.7% (10/15), 37.5% (6/16) and 7.1% (1/14) respectively. There was a significant difference between the low malignancy NHL and the high malignancy NHL (P < 0.005) in expression rate of P16 protein. It suggests that P16 protein expression may be one of the important parameters in estimating the prognosis of patients with NHL.

[Invasive fungal infection in 3447 autopsy cases]

OBJECTIVE

To evaluate the prevalence of invasive fungal infection at autopsy.

METHOD

To retrospectively analyse 3447 autopsy cases in Peking Union Medical College Hospital from 1953 to 1993.

RESULTS

There were 85 cases of invasive fungal infection at autopsy among 3447 cases. The prevalence steadily increased, especially during the recent 20 years. Among the 85 cases, only 5 patients were diagnosed clinically (5.9%). The primary diseases were mainly leukemia, cancer, and sepsis. Lung was involved in 70% of the cases, and 85% of the pathogens were fungi.

CONCLUSIONS

Fungus has become a major pathogen in nosocomial infection. The prophylactic use of antifungal agents is recommended in high-risk patients because of the difficulty to establish the clinical diagnosis of invasive fungal infection.

Direct cytotoxicity of HIV-1 envelope protein gp120 on human NT neurons

A new in vitro system comprising a pure population of neurons, human NT cells, was used to characterize the direct neurotoxic effect of HIV-1 envelope protein gp120. Cytotoxicity was monitored by a quantitative assay after exposure to recombinant gp120 in the presence or absence of other reagents. Treatment of mature NT neurons with various doses of gp120 for 24 h caused a decrease of up to 27% in the number of viable cells. This neurotoxicity was abolished by co-treatment with either D-2-amino-5-phosphonopentanoic acid (APV), MK801 or nimodipine, or by culturing cells in a Ca(2+)-free environment. Taken together, these data indicate that gp120 exerts a direct neurotoxic effect by acting through NMDA receptors and Ca2+ channels.

[Nosocomial bacterial infection in comprehensive intensive care unit]

OBJECTIVE

To establish the prevalence of nosocomial bacterial infection and changes in resistance in a comprehensive intensive care unit.

METHODS

We retrospectively analyzed all the bacterial isolates of ICU, PUMC Hospital from 1989 to 1994, such as the species and resistance pattern.

RESULTS

Among all bacterial isolates, the percentage of Gram-positive cocci steadily increased (16% in 1989, 33% in 1994), while that of Gram-negative bacilli decreased (84% in 1989, 67% in 1994). The most prevalent isolates of Gram-negative pathogens were Pseudomonas aeruginosa, Acinetobacter baumanii, inducible Enterobacteriaceae and Xanthomonas maltophilia, with imipenem and amikacin as the most susceptible antibiotics. Enterococci, oxacillin-resistant Staphylococcus epidermidis and oxacillin-resistant Staphylococcus aureus accounted for 44%, 21% and 10%, respectively. The resistant rate of these three Gram-positive bacteria to vancomycin were 19%, 0% and 0%.

CONCLUSION

Understanding of the epidemiological data and changes of bacterial resistance profile is prerequisite to rational use of antibiotics, which is crucial to reducing the resistance of nosocomial infection pathogens.

Efficient transduction of human neurons with an adeno-associated virus vector

An adeno-associated virus vector containing a lacZ gene driven by a CMV immediate-early promoter (AAV beta-gal) was evaluated with respect to its transduction efficiency and integration ability in nondividing human NT neurons. A dose-dependent pattern in transduction efficiency of the AAV beta-gal was demonstrated immunocytochemically, with up to 100% of the neurons expressing the gene product. No neurotoxic effects of the vector were detected. Quantitative PCR analyses of high molecular weight cellular DNA from the transduced neurons indicated that the copy number of the AAV beta-gal genome increased gradually in a time dependent manner, suggesting a slow but progressive rate of vector integration over a period of approximately 1 week following transduction. Equal or greater transduction efficiency of the AAV beta-gal into NT neurons than into a standard target cell line indicated that the NT neurons were readily susceptible to AAV-mediated gene transfer. This study demonstrates that AAV-based vectors can efficiently transduce and stably express a foreign gene in post-mitotic human neurons.

[The correlation between gastric intramucosal pH and oxygen delivery in patients with septic shock]

We studied the correlation of intramucosal pH (pHi), oxygen delivery (DO2) and oxygen consumption (VO2) in 21 patients with septic shock, and found that pHi decreased dramatically (P < 0.05) in nonsurvivors while it had no significant change in survivors. In survivors, there was a positive correlation between pHi and DO2 (r = 0.71, P < 0.001), pHi and VO2 (r = 0.63, P < 0.001) when DO2 was below the critical level of 641 ml/min/m2. We concluded that the change of pHi is related with the prognosis of septic shock. The correlation between pHi and DO2 proves the oxygen supply dependency of VO2. The hypoxia in tissue level is the main factor which results in a high mortality of septic shock patients. pHi is a reliable and useful parameter not only for prognosis, but also for titrating the therapy in septic shock if pHi is monitored serially together with DO2.

Decreased type II/type I TGF-beta receptor ratio in cells derived from human atherosclerotic lesions. Conversion from an antiproliferative to profibrotic response to TGF-beta1

Atherosclerosis and postangioplasty restenosis may result from abnormal wound healing. The present studies report that normal human smooth muscle cells are growth inhibited by TGF-beta1, a potent wound healing agent, and show little induction of collagen synthesis to TGF-beta1, yet cells grown from human vascular lesions are growth stimulated by TGF-beta1 and markedly increase collagen synthesis. Both cell types increase plasminogen activator inhibitor-1 production, switch actin phenotypes in response to TGF-beta1, and produce similar levels of TGF-beta activity. Membrane cross-linking of 125I-TGF-beta1 indicates that normal human smooth muscle cells express type I, II, and III receptors. The type II receptor is strikingly decreased in lesion cells, with little change in the type I or III receptors. RT-PCR confirmed that the type II TGF-beta1 receptor mRNA is reduced in lesion cells. Transfection of the type II receptor into lesion cells restores the growth inhibitory response to TGF-beta1, implying that signaling remains responsive. Because TGF-beta1 is overexpressed in fibroproliferative vascular lesions, receptor-variant cells would be allowed to grow in a slow, but uncontrolled fashion, while overproducing extracellular matrix components. This TGF-beta1 receptor dysfunction may be relevant for atherosclerosis, restenosis and related fibroproliferative diseases.

HIV-1 Tat modulates invasion by a bacterial enteric pathogen into a human intestinal cell line

OBJECTIVE

To explore the possibility that an HIV-1 gene product may modulate entry of an invasive enteric pathogen into a terminally differentiated human intestinal cell line. HIV-1 Tat was selected for investigation because of its unique ability to cross cell membranes.

METHODS

After transient transfection of HT29-C1 cells with plasmids containing HIV-1 long terminal repeat (LTR)-lacZ plus a Tat expression cassette, or with a pSR-lacZ control plasmid, bacterial invasion assays were performed on both groups of cells utilizing a clinical Salmonella isolate. Assays were performed concurrently on a control group of non-transfected cells. A second series of experiments compared bacterial invasion into cells transfected with the Tat expression vector alone versus cells transfected with either an isogenic expression vector that did not make Tat, or with pSR-lacZ. Finally, the ability of exogenous Tat protein to transactivate an HIV-1 LTR-chloramphenicol acetyltransferase (CAT) plasmid which had been transfected into HT29-C1 cells and to modulate Salmonella invasion was also assessed.

RESULTS

HT29-C1 cells transfected with a Tat expression vector, either alone or in combination with another plasmid, were significantly less susceptible to bacterial invasion than cells that either did not undergo transfection, were transfected with an otherwise isogenic expression vector without Tat, or transfected with an unrelated plasmid. Duplicate experiments also demonstrated that exogenous purified Tat protein transactivated an HIV-1 LTR-CAT plasmid which had been transfected into HT29-C1 cells and inhibited Salmonella invasion compared with unexposed cells.

CONCLUSION

HIV-1 Tat inhibits Salmonella invasion of a human enterocyte cell line whether the protein is expressed intracellularly or provided exogenously.

Specific inhibition of eIF-5A and collagen hydroxylation by a single agent. Antiproliferative and fibrosuppressive effects on smooth muscle cells from human coronary arteries

Restenosis occurs in 35% of patients within months after balloon angioplasty, due to a fibroproliferative response to vascular injury. These studies describe a combined fibrosuppressive/antiproliferative strategy on smooth muscle cells cultured from human primary atherosclerotic and restenotic coronary arteries and from normal rat aortas. L-Mimosine suppressed the posttranslational hydroxylation of the precursors for collagen and for eukaryotic initiation factor-5A (eIF-5A) by directly inhibiting the specific protein hydroxylases involved, prolyl 4-hydroxylase (E.C. 1.14.11.2) and deoxyhypusyl hydroxylase (E.C. 1.14.99.29), respectively. Inhibition of deoxyhypusyl hydroxylation correlated with a dose-dependent inhibition of DNA synthesis. Inhibition of prolyl hydroxylation caused a dose-dependent reduction in the secretion of hydroxyproline-containing protein and decreased the formation of procollagen types I and III. The antifibroproliferative action could not be attributed to nonspecific or toxic effects of mimosine, appeared to be selective for the hydroxylation step in the biosynthesis of the procollagens and of eIF-5A, and was reversible upon removal of the compound. The strategy of targeting these two protein hydroxylases has important implications for the pathophysiology of restenosis and for the development of agents to control fibroproliferative diseases.

Interleukin 4 receptor signaling in human monocytes and U937 cells involves the activation of a phosphatidylcholine-specific phospholipase C: a comparison with chemotactic peptide, FMLP, phospholipase D, and sphingomyelinase

Interleukin 4 (IL-4) diminishes cytokine activation of human macrophage. IL-4 binding to monocyte IL-4R is associated with protein kinase C (PKC) translocation to a nuclear fraction. The cleavage of diacyglycerol (DAG), an activator of PKC, from membrane phospholipids was investigated to define the proximal events of IL-4R signaling. IL-4 induced a statistically significant time-and dose-dependent generation of DAG. The IL-4-triggered production of DAG was not derived from phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolysis, since neither cytosolic calcium flux nor liberation of inositol phosphates was detected in response to IL-4. Experiments were performed using [14C-methyl]choline-labeled U937 cells and monocytes to determine whether IL-4R activated phospholipase C (PLC), PLD, or PLA2 to use membrane phosphatidylcholine (PC) to form DAG. IL-4 induced a time- and dose-dependent increase of phosphocholine (pchol) with concomitant degradation of membrane PC (p < 0.05 compared with control). The finding that the peak reduction of PC was equivalent to peak production of pchol suggested that IL-4R signaling involved the activation of a PC-specific PLC. Changes in choline (chol) or lyso-PC and glycerolphosphocholine, the respective products of PC cleavage by PLD or PLA2, were not detected in IL-4-treated cells. In contrast, exogenous PLD induced an increase in chol and concomitant loss of membrane PC. Additional investigation suggested that IL-4R signaling does not involve PLD. In cells labeled with L-lyso-3-PC 1-[1-14C]palmitoyl, PLD but not IL-4, increased the production of phosphatidic acid (PA) and phosphatidyl-ethanol when pretreated with ethanol. Propranolol, an inhibitor of phosphatidate phosphohydrolase, and calyculin A, a phosphatase 1 and 2A inhibitor, blocked DAG production in response to FMLP but not to IL-4. In propranolol pretreated cells, PMA but not IL-4 triggered the production of PA and lowered the amount of DAG. Evidence that PLA2 is not coupled to IL-4R is the detection of arachidonate production in response to FMLP but not to IL-4. Furthermore, IL-4R is not coupled to sphingomyelinase (SMase) since IL-4, unlike exogenous SMase, did not generate ceramide but induced the hydrolysis of PC to pchol that was comparable to exogenous PLC. In summary, IL-4R signaling in monocytes and U937 cells involves PLC and not PLD, PLA2, or SMase, and it uses PC and not PIP2 to form DAG.

Protection of transforming growth factor-beta 1 activity by heparin and fucoidan

The transforming growth factor-beta (TGF-beta) family of proteins exert diverse and potent effects on proliferation, differentiation, and extracellular matrix synthesis. However, relatively little is known about the stability or processing of endogenous TGF-beta activity in vitro or in vivo. Our previous work indicated that 1) TGF-beta 1 has strong heparin-binding properties that were not previously recognized because of neutralization by iodination, and 2) heparin, and certain other polyanions, could block the binding of TGF-beta 1 to alpha 2-macroglobulin (alpha 2-M). The present studies investigated the influence of heparin-like molecules on the stability of the TGF-beta 1 signal in the pericellular environment. The results indicate that heparin and fucoidan, a naturally occurring sulfated L-fucose polymer, suppress the formation of an initial non-covalent interaction between 125I-TGF-beta 1 and activated alpha 2-M. Electrophoresis of 125I-TGF-beta 1 showed that fucoidan protects TGF-beta 1 from proteolytic degradation by plasmin and trypsin. While plasmin caused little, if any, activation of latent TGF-beta derived from vascular smooth muscle cells (SMC), plasmin degraded acid-activated TGF-beta, and purified TGF-beta 1, and this degradation was inhibited by fucoidan. In vitro, heparin and fucoidan tripled the half-life of 125I-TGF-beta 1 and doubled the amount of cell-associated 125I-TGF-beta 1. Consistent with this protective effect, heparin- and fucoidan-treated SMC demonstrated elevated levels of active, but not latent, TGF-beta activity.

Changes in the host range and growth potential of an HIV-1 clone are conferred by the vpu gene

vpu, alone among the genes of human immunodeficiency virus type 1 (HIV-1), is unique to this virus, with no analogous reading frame evident in the genomes of either HIV-2 or the related SIVs. Effects of vpu upon levels of virus production from infected cells have been noted, but vpu is dispensable for HIV-1 replication in vitro and its significance in the natural viral life cycle is unclear. We have now identified and characterized a major influence of vpu upon the growth and host cell range of a cloned recombinant HIV-1. This effect required the presence of a second determinant mapping to the 3' end of the env gene, and was not detected in clones incorporating an env gene derived from a different strain of the virus. This indicates that important effects of vpu may have been lost in some experimental systems because of the particular viruses used, and further suggests the involvement of a determinant in the transmembrane glycoprotein of the virus in the action of vpu.

Transforming growth factor-beta 1 is a heparin-binding protein: identification of putative heparin-binding regions and isolation of heparins with varying affinity for TGF-beta 1

Previous studies indicated that a major factor in heparin's ability to suppress the proliferation of vascular smooth muscle cells is an interaction with transforming growth factor-beta 1 (TGF-beta 1). Heparin appeared to bind directly to TGF-beta 1 and to prevent the association of TGF-beta 1 with alpha 2-macroglobulin (alpha 2-M). The present studies indicate that 20-70% of iodinated TGF-beta 1 binds to heparin-Sepharose and the retained fraction is eluted with approximately 0.37 M NaCl. Native, unlabelled platelet TGF-beta 1, however, is completely retained by heparin-Sepharose and eluted with 0.9-1.2 M NaCl. Using synthetic peptides, the regions of TGF-beta 1 that might be involved in the binding of heparin and other polyanions were examined. Sequence analysis of TGF-beta 1 indicated three regions with a high concentration of basic residues. Two of these regions had the basic residues arranged in a pattern homologous to reported consensus heparin-binding regions of other proteins. The third constituted a structurally novel pattern of basic residues. Synthetic peptides homologous to these three regions, but not to other regions of TGF-beta 1, were found to bind to heparin-Sepharose and were eluted with 0.15 M-0.30 M NaCl. Only two of these regions were capable of blocking the binding of heparin to 125I-TGF-beta. Immobilization of these peptides, followed by affinity purification of heparin, indicated that one peptide was capable of isolating subspecies of heparin with high and low affinity for authentic TGF-beta 1. The ability of TGF-beta 1 to bind to heparin or related proteoglycans under physiological conditions may be useful in understanding the biology of this pluripotent growth and metabolic signal. Conversely, a subspecies of heparin molecules with high affinity for TGF-beta 1 may be a factor in some of the diverse biological actions of heparin.

Nonrandom distribution of gp120 N-linked glycosylation sites important for infectivity of human immunodeficiency virus type 1

More than 20 consensus N-linked glycosylation sites occur in the gp120 coding sequence of most isolates of human immunodeficiency virus type 1. Based on the N-linked glycosylation pattern of a well-characterized recombinant gp120, it is likely that N-linked sugars are present at most, if not all, of the consensus glycosylation sites of the heavily glycosylated gp120. In this study, we evaluated the relative importance of each of the 24 N-linked glycosylation sites of gp120 in the molecular clone HXB2 to viral infectivity. The ability of HXB2-derived mutants, each having 1 of the 24 N-linked glycosylation sites mutated by site-directed mutagenesis, to infect CD4-positive SupT1 cells was compared with that of the wild-type virus. We found that most of the individual consensus N-linked glycosylation sites are dispensable for viral infectivity. The five consensus N-linked glycosylation sites that are likely to have important roles in infectivity are all located in the amino-terminal half of gp120, indicating that the N-linked glycosylation sites that are important for infectivity of human immunodeficiency virus type 1 are not randomly distributed in gp120. We predict that a partially glycosylated gp120 with most of the dispensable N-linked glycosylation sites removed may be a better vaccine candidate than the fully glycosylated gp120.

Role of conserved gp41 cysteine residues in the processing of human immunodeficiency virus envelope precursor and viral infectivity

All animal retroviruses whose nucleotide sequences have been determined contain two or three closely spaced cysteine residues in the extracellular domain of the env-encoded transmembrane protein. Using human immunodeficiency virus type 1 gp41 as a working model, the functional significance of these highly conserved cysteines was investigated. We report here that substituting the two conserved cysteine residues in this domain of gp41 with glycine residues resulted in the loss of viral infectivity, which could be attributed to severe impairment in the processing of gp160 precursor to gp120.