[Single particle source apportionment of atmospheric aerosol based on proton microprobe]

A proton microprobe with high resolution and high sensitivity was applied to analyze atmospheric aerosol in the people's park in Shanghai urban for single particle source apportionment. The results showed that the sum of the average contribution rates from the sources of soil dust, building construction dust, vehicle exhaust and metallurgical industry, which are the main pollution sources of atmospheric aerosol in Shanghai urban and surpasses 80%. Besides, about 13% of the particles could not be identified. On the basis of cluster analysis of these particles, they are preliminary known belonging to two different individual sub-pollution sources and a new unidentified pollution source.

Gene expression profile changes in initiation and progression of squamous cell carcinoma of esophagus

Tumorigenesis is a complex process involving multiple genes. As a step toward understanding the complicated changes between normal and malignant cells, this report focused on gene expression profile variations among normal and abnormal esophageal epithelium tissues. The cDNA microarray approach was used to investigate gene expression profiles of 5 different stages during initiation and progression of esophageal cancer. According to pathological characteristics, these 5 stages were normal, dysplasia I (mild dysplasia), dysplasia II (moderate dysplasia), carcinoma in situ (CIS) and squamous cell carcinoma of esophagus (SCC). Comparing and analyzing those gene expression profiles, we observed that the expression levels of many genes changed in dysplasia I and some known tumor-related genes were over-expressed or under-expressed in all 4 abnormal stages. Using principle component analysis we identified a set of genes that may play an important role in tumor development. Hybridization data were confirmed by semi-quantitative reverse transcription-polymerase chain reaction and immunohistochemistry. These results suggest that cDNA microarray technology is a useful tool to discover genes frequently involved in esophageal neoplasia and provides novel clues to diagnosis, early detection and intervention of SCC.

Helix packing of functionally important regions of the cardiac Na(+)-Ca(2+) exchanger

In a revised topological model of the cardiac Na(+)-Ca(2+) exchanger, there are nine transmembrane segments (TMSs) and two possible re-entrant loops (Nicoll, D. A., Ottolia, M., Lu, Y., Lu, L., and Philipson, K. D. (1999) J. Biol. Chem. 274, 910-917; Iwamoto, T., Nakamura, T. Y., Pan, Y., Uehara, A., Imanaga, I., and Shigekawa, M. (1999) FEBS Lett. 446, 264-268). The TMSs form two clusters separated by a large intracellular loop between TMS5 and TMS6. We have combined cysteine mutagenesis and oxidative cross-linking to study proximity relationships of TMSs in the exchanger. Pairs of cysteines were reintroduced into a cysteine-less exchanger, one in a TMS in the NH(2)-terminal cluster (TMSs 1-5) and the other in a TMS in the COOH-terminal cluster (TMSs 6-9). The mutant exchanger proteins were expressed in HEK293 cells, and disulfide bond formation between introduced cysteines was analyzed by gel mobility shifts. Western blots showed that S117C/V804C, A122C/Y892C, A151C/T815C, and A151C/A821C mutant proteins migrated at 120 kDa under reducing conditions and displayed a partial mobility shift to 160 kDa under nonreducing conditions. This shift indicates the formation of a disulfide bond between these paired cysteine residues. Copper phenanthroline and the cross-linker N', N'-o-phenylenedimaleimide enhanced the mobility shift to 160 kDa. Our data suggest that TMS7 is close to TMS3 near the intracellular side of the membrane and is in the vicinity of TMS2 near the extracellular surface. Also, TMS2 must adjoin TMS8. This initial packing model of the exchanger brings two functionally important domains in the exchanger, the alpha 1 and alpha 2 repeats, close to each other.

[Bcl-2 antisense oligodeoxyribonucleotide increases apoptosis of lung carcinoma cells induced by cisplatin]

OBJECTIVE

To study the effect of antisense oligodeoxyribonucleotide (ODN) to apoptotic suppress gene bcl-2 on apoptosis of lung carcinoma cells induced by cisplatin.

METHODS

The lung carcinoma cells expressing bcl-2 were chosen to participate in this experiment. Cultured cells were divided into 7 groups: ODN, nonsense, ODN + cisplatin, nonsense + cisplatin, cisplatin, lipofectin and control. Bcl-2 antisense or nonsense mixed with lipofectin was added into above corresponding cultured cells. After cultured for 6 hours, cisplatin was added into corresponding groups. The cells were cultured again for 16 hours. And then, the cells were smeared on slides. Apoptotic cells were labeled with TdT-mediated dUTP nick end labeling (TUNEL) method on cell smears. Apoptotic index (AI) was counted to show the percentage of apoptotic cancer cells. The immunocytochemistry was used to detect the expression of bcl-2 in carcinoma cells.

RESULTS

The bcl-2 expression of cancer cell in ODN group was significantly decreased compared to the control and nonsense groups. The AI of ODN + cisplatin group was 16.4 +/- 1.7, cisplatin group 4.1 +/- 0.8, antisense group 5.9 +/- 0.2, nonsense group 3.3 +/- 0.7, nonsense + cisplatin 7.6 +/- 1.1, lipofectin 5.1 +/- 0.9, control group 3.6 +/- 0.6. The AI of antisense + cisplatin group was significantly higher than that of other groups.

CONCLUSION

Antisense oligodeoxyribonucleotide to bcl-2 can inhibit significantly the expression of bcl-2 of lung cancer cells and increase apoptosis of cancer cells induced by cisplatin.

c-Crk, a substrate of the insulin-like growth factor-1 receptor tyrosine kinase, functions as an early signal mediator in the adipocyte differentiation process

Differentiation of 3T3-L1 preadipocytes into adipocytes is induced by a combination of inducers, including a glucocorticoid, an agent that elevates cellular cAMP, and a ligand of the insulin-like growth factor-1 receptor. Previous studies have implicated protein-tyrosine phosphatase (PTPase) HA2, a homologue of PTPase 1B, in the signaling cascade initiated by the differentiation inducers. Vanadate, a potent PTPase inhibitor, blocks adipocyte differentiation at an early stage in the program, but has no effect on the mitotic clonal expansion required for differentiation. Exposure of preadipocytes to vanadate along with the inducing agents led to the accumulation of pp35, a phosphotyrosyl protein that is a substrate for PTPase HA2. pp35 was purified to homogeneity and shown by amino acid sequence and mass analyses of tryptic peptides to be c-Crk, a known cytoplasmic target of the insulin-like growth factor-1 receptor tyrosine kinase. Transfection of 3T3-L1 preadipocytes with a c-Crk antisense RNA expression vector markedly reduced c-Crk levels and prevented differentiation into adipocytes. Studies with C3G, a protein that binds to the SH3 domain in c-Crk, showed that phosphorylation of c-Crk rendered the SH3 domain inaccessible to C3G. Taken together, these findings indicate that locking c-Crk in the phosphorylated state with vanadate prevents its participation in the signaling system that initiates adipocyte differentiation.

Dynamic process of information transmission complexity in human brains

Based on a complexity analysis of mutual information transmission of EEG developed by us [Xu J, Liu Z, Liu R, Yang Q (1997) Physica D 106: 363-374], dynamic processes of the complexity of mutual information transmission in human brains were studied. To diminish possible problems due to coarse graining preprocessing, some new measures of complexity were used. The results show that, just before and after generalized seizures, the complexities of almost all information transmission between different brain areas drop significantly; there is also a temporary decrease of complexity when subjects shift their attention. The above facts suggest that there is a transient decrease of information transmission complexity when brain state changes occur suddenly. Mental arithmetic tasks activate the left temporal lobe to exchange more information with other brain areas. The results hint that the methods used here might be an approach to observe quick processes in the living brain.

Mutations in the E1 hydrophobic domain of rubella virus impair virus infectivity but not virus assembly

Rubella virus (RV) virions contain three structural proteins, a capsid protein that interacts with viral genomic RNA to form a nucleocapsid and two membrane glycoproteins, E2 and E1. We found that substitution of either an aspartic acid residue at Gly93 (G93D) or a glycine residue at Pro104 (P104G) in the internal hydrophobic domain of E1 affected virus infectivity but not virus assembly. Viruses carrying G93D and P104G mutations had impaired infectivity, reduced 1,000-fold and 10-fold, respectively. A revertant was isolated from the G93D mutant. Sequencing analysis showed that the substituted aspartic acid residue in G93D mutant had reverted to the original glycine residue, suggesting the involvement of Gly93 in membrane fusion during viral entry.

[Protective immunity induced by anti-idiotypic monoclonal antibody NP30 of Schistosoma japonicum in goats]

OBJECTIVE

To observe the protective immunity in goats induced by active immunization with anti-idiotypic monoclonal antibody NP30 of S. japonicum.

METHODS

Goats were randomly divided into two groups. Experimental group had 12 goats. The NP30 was intramuscularly injected with a dosage of 1 000 microgram into the hind leg for three dosages continuously. The goats were challenged with cercariae eight weeks after the third immunization. Ten goats in the control group were intramuscularly injected with SP2/0 ascites and challenged with cercariae at the same time as the experimental group. All goats were killed at the twelfth week post-challenge.

RESULTS

Active immunization with NP30 could produce a protection rate of 42.78% in goats. The number of eggs in liver and feces in the goats immunized with NP30 was decreased by 35.83% and 25%, respectively. The size and number of egg granulomas in the liver were lessened obviously and the weight of the goats increased significantly.

CONCLUSION

Active immunization with NP30 could induce a good protection in goats against the infection with Schsitosoma cercariae.

Vasoactive effects of adrenotensin and its interactions with adrenomedullin

OBJECTIVE

To investigate the vasoactive effects of adrenotensin and the interactions between adrenotensin and adrenomedullin (ADM).

METHODS

Isolated rat aortic tension, rat mean arterial pressure and 3H-TdR incorporation of rat vascular smooth muscle cells were measured. Isolated rat aortas were incubated in K-H solution containing adrenomedullin or adrenotensin. The released adrenotensin or adrenomedullin (in incubation medium) from rat aortas was measured by radioimmunoassay.

RESULTS

1 x 10(-8) and 1 x 10(-7) mol/L adrenotensin augmented rat aortic tension in a dose-dependent manner (P < 0.01). An intravenous bolus injection of adrenotensin (2.5 nmol/kg, i.v.) increased the mean arterial pressure by 28% in anesthetized rats (P < 0.01). 1 x 10(-7) mol/L adrenotensin increased 3H-TdR incorporation in cultured rat vascular smooth muscle cells by 55% (P < 0.01). Adrenomedullin inhibited these activities of adrenotensin to different extents. 1 x 10(-9), 1 x 10(-8) and 1 x 10(-7) mol/L adrenotensin decreased adrenomedullin release rates by 19%, 35% and 46%, respectively (P < 0.05 or P < 0.01) and 1 x 10(-8) mol/L adrenomedullin also inhibited adrenotensin release by 45% from rat aorta (P < 0.01).

CONCLUSION

Adrenotensin is a novel peptide that elicits the activities of vasoconstriction, pressor effects and induces the proliferation of vascular smooth muscle cells. There is antagonism in vascular activities and reciprocal inhibition in the release between adrenotensin and adrenomedullin. These interactions are manifestations of intramolecular regulation of proadrenomedullin (Pro-ADM).

Anti-fecundity immunity in mice immunized with anti-idiotypic monoclonal antibody NP30 of Schistosoma japonicum

OBJECTIVE

To observe the effects of anti-fecundity and anti-embryonation immunity of anti-idiotypic monoclonal antibody NP30 of Schistosoma japonicum on female adult worm.

METHODS

The active immunization of C57BL/6 mice was conducted by means of three intraperitoneal injections of NP30. The control group was injected with SP2/0 ascites intraperitoneally.

RESULTS

On the twenty-seventh day after challenge infection, the number of eggs in the liver tissue and in uterus of the group immunized with NP30 decreased by 30.91% and by 38.55%, respectively. On the thirty-ninth day after the challenge infection, the number of mature eggs in the liver tissue of the group immunized with NP30 decreased by 66.63% and the number of dead eggs increased by 60.66%.

CONCLUSIONS

NP30, with which mice were actively immunized, possesses double effects of anti-fecundity and anti-embryonation immunity on female adult worm of Schistosoma japonicum, therefore it can be used as a promising candidate of anti-pathologic vaccine molecule against Schistosomiasis japonica.

Modified Aloe barbadensis polysaccharide with immunoregulatory activity

Aloe barbadensis polysaccharide was partially digested with cellulase and further purified by dialysis, stepwise ethanol precipitation, and size exclusion chromatography. Crude modified Aloe polysaccharide (MAP) activated macrophage cells and stimulated fibroblast growth. Under the same conditions, native Aloe barbadensis gel had no effect on macrophage activation. MAP prevented ultraviolet B (UVB) irradiation-induced immune suppression as determined by contact hypersensitivity (CHS) response in C3H/HeN mice. This in vivo activity was correlated with the activity of MAP to inhibit UVB irradiation-induced tumor necrosis factor alpha (TNF-alpha) release from human epidermoid carcinoma cells (KB cells). MAP with an average molecular weight of 80,000 Dalton (Da) contained mannose, galactose, and glucose in a ratio of 40:1.4:1.0. MAP was likely a linear, highly acetylated molecule.

[The use of interposed colon for endothoracic anastomosis in esophageal surgery]

OBJECTIVE

To study the use of interposed colon for endothoracic anastomosis in esophageal surgery.

METHODS

From May 1991 to December 1993, 28 cases were selected with carcinoma of the middle and/or lower segment of esophagus. After tumor resection, a segment of transverse colon with peduncle was anastomosed in its peristaltic direction to the two ends of the severed esophagus. The vagus nerve innervating esophagus and stomach was intact, the anastomical position of the esophagus-cardia hiatus and the stomach were preserved.

RESULTS

No anastomosis leakage, reflux esophagitis or the symptoms caused by the endothoracic stomach occured in this group. The digestive function of the patients remained good. The 1-, 3-, 5-year survical rate was 96.6%, 92.8% and 71.4%, respectively.

CONCLUSION

The interposed colon for endothoracic anastomosis is a comparatively ideal method for the reconstruction of esophagus following resection of cancer of mid and lower thind of the esophagus.

Alpha2-macroglobulin enhances the clearance of endogenous soluble beta-amyloid peptide via low-density lipoprotein receptor-related protein in cortical neurons

Apolipoprotein E and alpha2-macroglobulin (alpha2M) are genetic risk factors for late-onset Alzheimer's disease, and both bind a cell surface receptor, the low-density lipoprotein receptor-related protein (LRP). To investigate the role of LRP on preventing the accumulation of beta-amyloid peptide (A beta), we examined the effects of alpha2M on the clearance of endogenous A beta. Studies were performed in primary Tg2576 transgenic mouse cortical neuronal cultures expressing human mutant amyloid precursor protein (APP) 695. This system allowed us to follow endogenous A beta using immunoblots to detect monomeric forms of the peptide. A beta and APP levels were measured in conditioned media. We found that activated alpha2M (alpha2M*) substantially decreased soluble A beta levels and had no effect on secreted or full-length APP levels. Native alpha2M, which is not a ligand for LRP, did not affect A beta levels. The receptor-associated protein, which inhibits interaction of all ligands with LRP in vitro, prevented alpha2M*-induced decreases of soluble A beta levels. These data suggest that alpha2M* affects soluble A beta clearance rather than A beta production. Further studies showed that similar A beta clearance via an LRP-mediated pathway was observed after treatment with another LRP ligand, lactoferrin. Taken together, these data demonstrate that alpha2M* enhances the clearance of soluble A beta via LRP in cortical neurons.

[Analyze T lymphocyte subsets of HIV/AIDS patients by flowcytometer]

OBJECTIVE

Using flowcytometer (FCM) to detect CD4+, CD8+ lymphocytes in peripheral blood, combine with clinical symptoms to evaluate the HIV/AIDS patients' immune state.

METHODS

Anti-coagulated peripheral blood were obtained from 8 HIV-AIDS patients and 5 normal persons. After analyzing their total white cell counts, the whole blood was stained with two-color immunofluorescence using directly conjugated monoclonal antibody pairs, followed by lysis of red erythrocytes, fixation of lymphocytes, and analysis by flowcytometry. Multiplying the CD4 and CD8 percentages by the absolute number of lymphocytes obtained from the total white blood cell (WBC) count divide by the lymphocyte differential percentage, we got the CD4, CD8 counts.

RESULTS

The HIV/AIDS patients' CD4 counts were lower than those of normal controls'. Especially, the AIDS patients' CD4 counts were all below 200 cells/mm3 and their clinical symptoms were serious.

CONCLUSION

The HIV/AIDS patients' CD4 counts are highly correlated with their clinical symptoms. The result also shows that FCM is accurate, sensitive and reliable in CD4 count.

[Identification of mutations in the phenylalanine hydroxylase gene and exon 5 novel mutation Y166X(C-->G) in Yunnan]

OBJECTIVE

To identify the mutations of the phenylalanine hydroxylase gene in Yunnan so as to enhance the gene diagnosis of classical phenylketonuria (PKU) in that south-western province of China.

METHODS

Exons 4,5,6,7,10,11 and 12 of the phenylalanine hydroxylase(PAH) were analyzed in 13/14 children affected with classical PKU from Yunnan by using PCR-single strand conformation polymorphism (PCR-SSCP),PCR-ASO dot blot hybridization,allele specific polymerase chain reaction(ASPCR) and PCR-direct sequencing.

RESULTS

Five missense mutations, i.e. R243Q. (5/26), Y204C(3/28), G247V(1/26),R413P(2/28) and T418P(1/28);three nonsense mutations,i.e. Y166X(C-->G)(2/26),W326X(1/28) and Y356X(2/26);and one silent mutation(V399V)(2/26) were identified. The nonsense mutation Y166X(C-->G) should be a novel mutation as compared with the PAH Mutation Database.

CONCLUSION

Five kinds of popular PAH gene mutation (R243Q,Y204C,V399V,Y356X and R413P) identified in the people of Yunnan are similar to those in the northern people, but such characteristic is different from that in the southern people. This finding will enhance the efficacy in gene diagnosis of PKU and will be of reference value for studies of population and regional difference in the pattern of PAH mutation distribution.

Chronic interleukin-6 alters NMDA receptor-mediated membrane responses and enhances neurotoxicity in developing CNS neurons

Recent studies show that the cytokine interleukin-6 (IL-6) is expressed at elevated levels in the CNS in several disease states and contributes to the neuropathological process. The mechanisms through which IL-6 exerts its CNS effects are primarily unknown. We have investigated the pathophysiological effects of IL-6 on developing CNS neurons using a culture model system and a chronic treatment paradigm. Here, we show, using current- and voltage-clamp recordings, that chronic IL-6 treatment of developing cerebellar granule neurons increases the membrane and current response to NMDA and that these effects are the primary mechanism through which IL-6 produces an enhanced calcium signal to NMDA. We also show that calcium influx through voltage-sensitive calcium channels contributes to the enhanced calcium signal to NMDA in the IL-6-treated neurons in a developmentally regulated manner and that the membrane depolarization to NMDA is more sensitive to the NMDA receptor antagonist ifenprodil in the IL-6-treated neurons compared with control neurons at a late developmental stage, consistent with a larger proportion of NMDA receptors containing the NMDAR2B subunit in the IL-6-treated neurons. Additional studies show that IL-6 treatment reduces the number of granule neurons in culture and enhances neurotoxicity involving NMDA receptors. These results support a pathological role for IL-6 in the CNS and indicate that NMDA receptor-mediated functions are likely to play a critical role in neuropathological changes observed in CNS diseases associated with elevated CNS levels of IL-6.

Effects of mutations in the rubella virus E1 glycoprotein on E1-E2 interaction and membrane fusion activity

Rubella virus (RV) virions contain two glycosylated membrane proteins, E1 and E2, that exist as a heterodimer and form the viral spike complexes on the virion surface. Formation of an E1-E2 heterodimer is required for transport of E1 out of the endoplasmic reticulum lumen to the Golgi apparatus and plasma membrane. To investigate the nature of the E1-E2 interaction, we have introduced mutations in the internal hydrophobic region (residues 81 to 109) of E1. Substitution of serine at Cys82 (mutant C82S) or deletion of this hydrophobic domain (mutant dt) of E1 resulted in a disruption of the E1 conformation that ultimately affected E1-E2 heterodimer formation and cell surface expression of both E1 and E2. Substitution of either aspartic acid at Gly93 (G93D) or glycine at Pro104 (P104G) was found to impair neither E1-E2 heterodimer formation nor the transport of E1 and E2 to the cell surface. Fusion of RV-infected cells is induced by a brief treatment at a pH below 6. 0. To test whether this internal hydrophobic domain is involved in the membrane fusion activity of RV, transformed BHK cell lines expressing either wild-type or mutant spike proteins were exposed to an acidic pH and polykaryon formation was measured. No fusion activity was observed in the C82S, dt, and G93D mutants; however, the wild type and the P104G mutant exhibited fusogenic activities, with greater than 60% and 20 to 40% of the cells being fused, respectively, at pH 4.8. These results suggest that it is likely that the region of E1 between amino acids 81 and 109 is involved in the membrane fusion activity of RV and that it may be important for the interaction of that protein with E2 to form the E1-E2 heterodimer.

[Surgical treatment of aortopulmonary septal defect]

OBJECTIVE

To study the surgical treatment of aortopulmonary septal defect.

METHOD

From January 1983 to December 1996, 5 patients with aortopulmonary septal defect (APSD) (2 male and 3 female) aged from 6 to 34 years (mean 17.4 years) underwent surgical treatment. According to Mori's were classification, 5 patients belonged to type I, 2 type II and 1 type III. The diameters of the defect ranged from 1.0 to 3.0 cm. The operations were performed under moderate hypothermic cardiopulmonary bypass. Pulmonary artery incision was performed, in 3 patients while aortic incision in the other 2. All defects were repaired by Dacron patch.

RESULT

There were no operative deaths and postoperative complications. During follow-up of 10 months to 12 years, no late complications and deaths were found.

CONCLUSION

The operation should be done early as possible whenever the diagnosis is established. The surgical repair should be taken under cardiopulmonary bypass. To chose an incision on the aorta is more reasonable than on the pulmonary artery. The use the dacron patch can prevent stenosis and recanalization after operation.

[Effects of artemisia capillaris on blood glucose and lipid in mice]

The effects of Artemisia capillaris Thunb (AC) on blood glucose and lipid in mice were studied and its effective mechanism was explained. The results showed that hyperglycemic effect in aloxan-induced mice was inhibited (P < 0.01); that hyperglycemica in DM mice was decreased (P < 0.05); but the change of fasting blood glucose (FBG) in normal and hyperlipidemia mice was not significant (P < 0.05); that the level of total cholesterol (TC) and/or atherosclerotic index (AI) was decreased (P < 0.01-0.05) and the content of high density lipoprotein cholesterol (HDL-C) was increased in the above different model mice (P < 0.01-0.05). These results indicated that the AC would have the similar hypoglycemic effect as biguanide-drugs, improve endogenous and exogenous metabolic derangement in blood lipid. These suggest that AC could be used to protect and treat DM and its chronic complication.

[Expression of surfactant protein SP-A, SP-B, and SP-C mRNA in lungs of rats with bleomycin-induced pulmonary fibrosis]

OBJECTIVE

The expressions of surfactant protein (SP)SP-A, SP-B, and SP-CmRNA in lungs of rats with bleomycin-induced pulmonary fibrosis were studied.

METHOD

A single dose of bleomycin(BLM) was intratracheal injected to induce pulmonary fibrosis of rats. Animals were killed at day 3, 7, 14 and 28 after BLM administration. The total RNA was extracted from the lung tissue. The expressions of SPsmRNA were analyzed with Northern blot.

RESULT

The number of alveolar type II epithelial cells increased in BLM-administered rats. The expressions of SP-A, SP-B and SP-CmRNA decreased at day 3 after BLM administration and decreased maximally at day 7, and then began to increase at day 14 and significantly increased at day 28, though they were still below the control levels.

CONCLUSION

The results show that the changes of expressions of SP-A, SP-B and SP-CmRNA occur during the development of bleomycin-induced pulmonary fibrosis in rats and they may play a role in the pathogenesis of lung fibrosis.

Neonatal alcohol exposure reduces NMDA induced Ca2+ signaling in developing cerebellar granule neurons

Glutamatergic neurotransmission through NMDA receptors is critical for both neurogenesis and mature function of the central nervous system (CNS), and is thought to be one target for developmentally-induced damage by alcohol to brain function. In the current study we examined Ca2+ signaling linked to NMDA receptor activation as a potential site for alcohol's detrimental effects on the developing nervous system. We compared Ca2+ signals to NMDA in granule neurons cultured from cerebella of rat neonates exposed to alcohol (ethanol) during development with responses to NMDA recorded in separated control groups. Alcohol exposure was by the vapor chamber method on postnatal days 4-7. An intermittent exposure paradigm was used where the pups were exposed to alcohol vapor for 2. 5 h/day to produce peak BALs of approximately 320 mg%. Control pups were placed in an alcohol-free chamber for a similar time period or remained with their mother. After culture under alcohol-free conditions for up to 9 days, Ca2+ signaling in response to NMDA was measured using fura-2 Ca2+ imaging. Results show that the peak amplitude of the Ca2+ signal to NMDA was significantly smaller in cultured granule neurons obtained from alcohol-treated pups compared to granule neurons from control pups. In contrast, the Ca2+ signal to K+ depolarization was not depressed by the alcohol treatment. Resting Ca2+ levels were also altered by the alcohol treatment. These results show that intermittent alcohol exposure during development in vivo can induce long-term changes in CNS neurons that affect the Ca2+ signaling pathway linked to NMDA receptors and resting Ca2+ levels. Such changes could play an important role in the CNS dysfunction associated with alcohol exposure during CNS development.

[Expressions of TNF alpha, PDGF in alveolar type II epithelial cells of rats with bleomycin-induced pulmonary fibrosis]

OBJECTIVE

The expressions of TNF alpha and PDGF in alveolar type II epithelial cells of rats with bleomycin(BLM)-induced pulmonary fibrosis were studied.

METHOD

A single intratracheal injection of BLM was administrated to induce pulmonary fibrosis of rats. Animals were killed at day 3,7,14 and 28 after BLM-administration. The immunohistochemical methods were used to analyze the expressions of TNF alpha and PDGF proteins in alveolar epithelium of rats. The total RNA was extracted from the alveolar type II epithelial cells of rats and the expressions of TNF alpha and PDGF mRNA were analyzed with Northern blot.

RESULT

TNF alpha and PDGF were expressed in the alveolar type II epithelial cells of BLM-administrated rats. The expression of TNF alpha elevated in median and late-stage of the process and reached the peak at day 28. While the expression of PDGF elevated in early-stage and reached the peak at day 7. By contrast, TNF alpha and PDGF weren't expressed in the alveolar type II epithelial cells of normal controls.

CONCLUSION

The results show that the alveolar type II epithelial cell from rats with pulmonary fibrosis overexpresses TNF alpha and PDGF and they may play roles in the pathogenesis of lung fibrosis.

Functional comparison of the three isoforms of the Na+/Ca2+ exchanger (NCX1, NCX2, NCX3)

Three distinct mammalian Na+/Ca2+ exchangers have been cloned: NCX1, NCX2, and NCX3. We have undertaken a detailed functional comparison of these three exchangers. Each exchanger was stably expressed at high levels in the plasma membranes of BHK cells. Na+/Ca2+ exchange activity was assessed using three different complementary techniques: Na+ gradient-dependent 45Ca2+ uptake into intact cells, Na+ gradient-dependent 45Ca2+ uptake into membrane vesicles isolated from the transfected cells, and exchange currents measured using giant patches of excised cell membrane. Apparent affinities for the transported ions Na+ and Ca2+ were markedly similar for the three exchangers at both membrane surfaces. Likewise, generally similar responses to changes in pH, chymotrypsin treatment, and application of various inhibitors were obtained. Depletion of cellular ATP inhibited NCX1 and NCX2 but did not affect the activity of NCX3. Exchange activities of NCX1 and NCX3 were modestly increased by agents that activate protein kinases A and C. All exchangers were regulated by intracellular Ca2+. NCX1-induced exchange currents were especially large in excised patches and, like the native myocardial exchanger, were stimulated by ATP. Results may be influenced by our choice of expression system and specific splice variants, but, overall, the three exchangers appear to have very similar properties.

The development of monoclonal antibody against rhTNF and its curative effects on E. coli infected mice

Fifteen hybridoma cell lines producing monoclonal antibodies (McAb) against recombinant human tumor necrosis factor alpha (rhTNFa) have been established by fusing SP 2/0 cells with spleen cells from a BALB/c mouse immunized with rhTNFa. Following J. M. Davis's Works, semi-solid medium was used for initial cloning. Five of them were studied further. Their main chromosome numbers range were 96 to 105, all of them were IgG1 subclass. The affinities of these McAbs were estimated to be 1.25 x 10(8) mol/L, 1.12 x 10(8) mol/L, 2.34 x 10(8) mol/L, 8.55 x 10(7) mol/L, 1.04 x 10(8) mol/L, respectively. Two groups of mice challenging with E. Coli (10(7) organisms), one group treated with 2 mg/kg anti-TNF monoclonal antibody, the other did not. There was a higher survival rate in treated group, the serum TNF level was significantly lower too, and the untreated mice had severe pathologic changes in viscera.

[Studies on difference of fluorescence activity and elution order of propranolol enantiomers by reversed-phase high performance liquid chromatography]

A sensitive RP-HPLC method for the determination of propranolol enantiomers was developed. It involves the formation of the monoester of propranolol with optically pure (R,R)-O,O'-diacetyl tartaric acid anhydride (DATAAN) in a dry, aprotic solvent with an excess of trichloroacetic acid. The resulting diastereomeric monoesters were easily resolved on a Shim-pack CLC-ODS column with the mobile phase system consisting of different proportions of 2% aqueous acetic acid (adjusted with concentrated ammonia to pH 3.48) and 90% aqueous methanol. And the column effluent was monitored by a fluorescence detector (lambda(ex) 296 nm, lambda(em) 340 nm). In our experiment, a very strong difference of the fluorescence absorbance of the two diastereomers was observed. After having studied chromatographic separation conditions including pH value, ionic strength and the volume percent of organic modifier in mobile phase, we presented the different configurations of the diastereomers and an intra-molecular hydrogen bond which exists only in the (R,R,S) isomer. These could account for the obvious difference of fluorescence activity of two diastereomeric monoesters and their elution order on the reversed-phase column. Our studies show that the intra-molecular hydrogen bond plays an important role on the polarity of the diastereomeric derivatives which determines their elution order and the fluorescence absorbance of the two diastereomers.

[The curative effects of anti-TNF monoclonal antibody in E. coli infected mice]

OBJECTIVE

To evaluate effects of monoclonal antibody (McAb) against TNFa on E. coli infected mice.

METHODS

30 mice (10 week old, Kunming) were divided equally into three groups. The first group, as a control, 200 microliters saline (NS)/mouse was injected intravenously; Second group (untreated group), only E. coli (10(7) organisms/200 microliters NS) were injected intra-abdominaly; Third group (treated group), E. coli (10(7) organisms) were injected intra-abdominal and McAb against TNF alpha 2 mg/kg dissolved in 200 microliters NS were injected intravenously. After 24 h, observed the survival rate, compared the serum TNF level in blood and investigated pathology of intestine, lung and liver.

RESULTS

There was a higher survival rate in treated group, with the serum TNF level lowered significantly, and the untreated mice had severe pathologic changes in viscera.

CONCLUSION

Using anti-TNF alpha McAb was effective in reducing mortality rate in mice after infected with E. coli, but could not prevent the pathologic changes.

The Escherichia coli polB locus is identical to dinA, the structural gene for DNA polymerase II. Characterization of Pol II purified from a polB mutant

Escherichia coli DNA polymerase II (Pol II) is a member of the group B, "alpha-like" family of DNA polymerases. Pol II is encoded by the damage-inducible dinA gene and exhibits SOS induction under the control of Lex A repressor. The polB gene was originally designated as the structural gene for Pol II based on the absence of detectable Pol II activity in cell lysates prepared from a strain containing the mutant polB100 allele. Because polB and dinA mapped at different chromosomal locations, it remained an open question whether polB, in addition to lexA, might be involved in regulating the expression of Pol II. We have cloned and sequenced the polB100 mutant allele, including adjacent surrounding sequences, and have expressed the mutant dinA gene from Pol B100 on a high copy number plasmid. Our sequence data reveal that polB and dinA represent the same gene and that the original transduction mapping of polB was inaccurate. We purified the mutant Pol B100 polymerase and show that it retains 5 to 10% of the wild-type level of polymerase activity. The Pol B100 mutation, Gly401 --> Asp401, is not located within any of the five conserved domains that define group B polymerases. Pol B100 retains a wild-type level of 3' --> 5' exonuclease activity. We suggest that the normal level of exonucleolytic proofreading associated with the mutant Pol B100 enzyme may explain the repeated failures, over the past two decades, to detect phenotypes in polB mutant strains.

Escherichia coli DNA polymerase II catalyzes chromosomal and episomal DNA synthesis in vivo

We have investigated a role for Escherichia coli DNA polymerase II (Pol II) in copying chromosomal and episomal DNA in dividing cells in vivo. Forward mutation frequencies and rates were measured at two chromosomal loci, rpoB and gyrA, and base substitution and frameshift mutation frequencies were measured on an F'(lacZ) episome. To amplify any differences in polymerase error rates, methyl-directed mismatch repair was inactivated. When wild-type Pol II (polB+) was replaced on the chromosome by a proofreading-defective Pol II exo- (polBex1), there was a significant increase in mutation frequencies to rifampicin resistance (RifR) (rpoB) and nalidixic acid resistance (NalR) (gyrA). This increased mutagenesis occurred in the presence of an antimutator allele of E. coli DNA polymerase III (Pol III) (dnaE915), but not in the presence of wild-type Pol III (dnaE+), suggesting that Pol II can compete effectively with DnaE915 but not with DnaE+. Sequencing the RifR mutants revealed a G --> A hot spot highly specific to Pol II exo-. Pol II exo- caused a significant increase in the frequency of base substitution and frameshift mutations on F' episomes, even in dnaE+ cells, suggesting that Pol II is able to compete with Pol III for DNA synthesis on F episomes.

Transmission factors of schistosomiasis japonica in the mountainous regions with type of plateau canyon and plateau basin

OBJECTIVE

To provide the scientific basis for formulating the control strategies of schistosomiasis japonica in mountainous regions in China Schistosomiasis Control Programme.

METHODS

We selected Chuanxing Village in Sichuan Province and Zhonghe Village in Yunnan Province as the two pilot areas for an epidemiological investigation according to their geographical and topographical characteristics, i.e. plateau canyon and plateau basin, respectively. Concentrated-egg hatching method in nylon tissue bag and Kato-Katz technique were used for the survey on prevalence rate and intensity of infection of man and domestic animals. Questionnaires were applied to investigating the infection sources, community behavior and the socioeconomic status. Snail survey and detection of cercaria-infested water bodies were conducted using routine techniques.

RESULTS

The results showed that in the endemic areas with plateau canyon, the key infection source was cattle. The infection rate in women was higher than that in men. The pattern of water-pollution was wild feces and the pollution source was cattle feces. Snails and infectious snails were distributed over the rice fields and the resident was infected through production activities. In plateau basin, the key infection source was human beings. The infection rate in men was higher than that in women. The pattern of water pollution was fertilization. The pollution source was human feces. Snails and infectious snails were distributed over the canals and ditches and the resident was infected through production and daily activities.

CONCLUSIONS

Therefore, it was suggested that the mountainous endemic areas should be divided into two sub-types, i.e., plateau basins and plateau canyons. The different control strategies should be formulated in accordance with the environmental situations and socioeconomic factors in the two kinds of endemic areas.

Tyrosine kinase activation is an immediate and essential step in hypotonic cell swelling-induced ERK activation and c-fos gene expression in cardiac myocytes

Hypotonic stress causes rapid cell swelling and initiates various cellular adaptive processes. However, it is unknown how cells initially sense low osmolarity and convert it into intracellular signals. We investigated the signal transduction mechanism initiated by hypotonic cell swelling in cardiac myocytes using c-fos expression as a nuclear marker. Treatment of myocytes with hypotonic culture media rapidly induced c-fos expression, whereas hypertonic stress had no effect. Transfection of c-fos reporter gene constructs suggested that the hypotonic stress response element maps to the serum response element of the c-fos promoter. Hypotonic stress immediately (within 5 s) activated tyrosine kinase activity, while activation of ERK1/2 peaked at 5 min. Stress-activated kinase (JNK1) was modestly activated at 15 min, whereas HOG1 like kinase (p38) was not activated by hypotonic stress. Extensive pharmacological studies indicated that only tyrosine kinase inhibitors suppressed the hypotonic swelling-induced c-fos expression. The effect of hypotonic stress was mimicked by chlorpromazine, which is known to cause membrane deformation. These results suggest that the signaling mechanism of hypotonic stress is distinct from that of hyperosmolar stress in mammalian cells. Tyrosine kinase activation is the earliest detectable cell response and plays an essential role in hypotonic swelling-induced ERK1/2 activation and c-fos expression.

Oral HIV-I recovery in the presence of periodontal disease

OBJECTIVE

To determine whether a significant association occurs between the presence of various periodontal diseases and recoverable infectious HIV-I in the saliva of injecting drug users.

DESIGN

Five hundred and fifty-one injecting drug users were recruited from various programs associated with the Beth Israel Medical Center. Examiners were 'blinded' to the subject's HIV-I serostatus. A socio-economic and risk factors' survey was conducted and a complete oral examination, including periodontal disease indices was performed. Whole saliva and blood were collected for virus culture.

MAIN OUTCOME MEASUREMENTS

Recovery of infectious HIV-I in saliva related to presence of periodontal diseases.

RESULTS

Those HIV-I seropositive subjects with periodontal diseases did not differ from those HIV-I seropositive subjects without periodontal disease in mean age and immune status. Less than 1% of the HIV-I seropositive subjects had cultivable HIV-I in their saliva while it was present in 78% of PBMCs and 35% of the sera. There was no significant association between infectious HIV-I in saliva, serum, or PBMCs and any of the various periodontal diseases.

CONCLUSIONS

The presence of periodontal disease in HIV-I seropositive injecting drug users does not appear to be a potential risk factor for infectious HIV-I in saliva, probably due to the various anti-viral components of saliva.

Active expression of G gamma globin gene on chromosome 11 with Yunnanese A gamma delta beta)0-thalassemia deletion in MEL cells

A permanent lymphocyte cell line of a heterozygote with Yunnanese (A gamma delta beta)0-thalassemia deletion, associated with an increased production of G gamma globin in adult, was founded using Epstein-Barr virus transformation. The hybrids of the lymphocyte cell and mouse erythroleukemia cell (MEL) were achieved and the hybrids containing human chromosome 11 were selected with the monoclonal antibody 53/6. The subclones containing only either the normal or the abnormal human chromosome 11 were separated and the expression of the human globin genes was studied. Expression of the beta-globin gene, but not the G gamma and A gamma, was observed in the hybrids containing only the normal human chromosome 11, while active expression of the G gamma globin gene was observed in the hybrids containing only the abnormal human chromosome 11. These results have confirmed that the DNA deletion in the beta-globin gene cluster is the cause of persistent active expression of the G gamma globin gene in the Yunnanese mutant.

Identification of domains in rubella virus genomic RNA and capsid protein necessary for specific interaction

In rubella virus-infected cells, genomic 40S and subgenomic 24S RNAs are present in the cytoplasm of infected cells. However, encapsidation by rubella virus capsid protein is specific for 40S genomic RNA. As a first step toward understanding the assembly of rubella virus nucleocapsid at the molecular level, the interaction between capsid protein and genomic RNA was studied by Northwestern (RNA-protein) blot analysis. RNA probes prepared by in vitro transcription were used to localize the RNA sequence that participates in binding to the capsid protein. We have identified a 29-nucleotide RNA sequence (nucleotides 347 to 375) that is essential for the binding. By using overlapping synthetic peptides of capsid protein, a peptide domain (residues 28 to 56) that displays specific RNA-binding activity of capsid protein has been located. This result suggests that the specific recognition of viral RNA during rubella virus assembly involves, at least in part, the nucleocapsid protein.

Cholinergic stimulation modulates negative inotropic effect of cocaine on ferret ventricular myocardium

We tested the hypothesis that the negative inotropic effect (NIE) of cocaine is mediated, at least in part, by cholinergic stimulation and can be correlated with the degree of adenosine 3',5'-cyclic monophosphate (cAMP) dependency of the inotropic state. Cardiac myocytes were isolated from left ventricles of ferrets and loaded with the fluorescent Ca2+ indicator indo 1. Cells were placed in physiological solution containing 2.0 mM Ca2+ and stimulated at 0.5 Hz and 30 degrees C. Cocaine decreased peak cell shortening and peak intracellular Ca2+ in a concentration-dependent manner (10(-8)-10(-4) M). The concentration-response curve of cocaine was shifted significantly downward compared with those of lidocaine and procaine in the same range of concentrations. Atropine (10(-6) M) shifted the concentration-response curve of cocaine, but not those of lidocaine and procaine, rightward, with a pA2 value (7.66) similar to that obtained with carbachol (7.99). With prior addition of isoproterenol (ISO, 10(-8) M) or increased Ca2+ (4.0 mM) to increase cell shortening to the same degree (approximately 60%), cocaine and carbachol decreased contractility to a significantly greater extent in ISO-stimulated myocytes. To clarify whether these treatments changed responsiveness of the contractile elements to Ca2+, the effect of 2,3-butanedione monoxime, an agent that interferes with the interaction of myosin and actin, was tested with previous addition of ISO or increased Ca2+, and no differential effect occurred. Therefore, we postulate that 1) the NIE of cocaine on myocytes is caused by decreased Ca2+ availability; 2) this effect is due to specific stimulation of cholinergic receptors in addition to other direct myocardial (probably local anesthetic) effects; and 3) the NIE correlates with the level of cAMP dependence of the inotropic state.

Interleukin-6 selectively enhances the intracellular calcium response to NMDA in developing CNS neurons

Increasing evidence supports a role for cytokines as chemical signals in the CNS, either under normal conditions or in the pathologic state. CNS levels of the cytokine interleukin-6 (IL-6) are known to be elevated in several diseases associated with developmental disorders and may contribute to the pathological state. To investigate the potential role of IL-6 in such disorders, neuronal effects of IL-6 were examined during development using an in vitro model system, cultured rat cerebellar granule neurons. The cultures were prepared from 8 d postnatal rat pups and exposed chronically to IL-6 (5 ng/ml) by addition to the culture medium. Neuronal effects of IL-6 were assessed by a comparison of calcium signals produced in control and IL-6 treated neurons by the glutamate receptor agonists NMDA and domoate and by K+ depolarization. IL-6 treatment significantly enhanced the response to NMDA and altered the developmental pattern of NMDA sensitivity, whereas only minor changes were observed for the response to domoate and K+. Reducing extracellular calcium and depleting intracellular stores significantly decreased the amplitude of the response to NMDA in control and IL-6 treated neurons. However, the IL-6 treated neurons were significantly more sensitive to these treatments than control neurons. These results suggest that elevated levels of IL-6 can significantly alter CNS neuron development and response to excitatory transmitters, and that IL-6 pretreatment selectively enhances the intracellular calcium responses to NMDA by altering the relative contribution of extracellular calcium influx and release of calcium from stores to the calcium signal.

[Surgical treatment of primary cardiac tumors]

From Jan. 1962 to Nov. 1994, 130 patients with primary cardiac tumors were performed in Shanghai Chest Hospital. There were 48 male and 82 female patients ranging in age from 16 to 73 (average 43.8 years). 123 (94.6%) had benign and 7 (5.4%) were malignant tumor. Cardiac myoxmas accounted for 91.1% of all benign neoplasias. 5 patients with benign and 1 patient with malignant tumor died early (within 30 days of operation). Of the 4 patients who died late, 3 had had malignant disease.

Brefeldin A and monensin arrest cell surface expression of membrane glycoproteins and release of rubella virus

The maturation of rubella virus (RV) glycoproteins E2 and E1 was examined by using brefeldin A (BFA) and monensin. BFA, which induces the rapid redistribution of Golgi enzymes residing in the Golgi complex into the endoplasmic reticulum (ER), was used to locate the intracellular site for the modification of carbohydrate side-chains on RV E1 and E2 proteins. The monovalent ionophore monensin, which inhibits intracellular transport of proteins through the ER-Golgi complex, was used to block the transport of E1 and E2 glycoproteins through the Golgi complex. BFA and monensin effectively blocked the cell surface expression of RV E2 and E1 proteins, secretion of an anchor-free form of E2 and budding of RV from the plasma membrane. For O-linked glycosylation, addition of N-acetylgalactosamine and galactose to E2 protein was found to take place in the medial to the trans Golgi. A dramatic change in the intracellular distribution of RV structural proteins was observed when transfected COS cells were treated with BFA or monensin, although the proteolytic processing of RV structural protein precursor was not affected. In the presence of BFA or monensin, virus release from infected Vero cells was only 0.1% of the intracellular virus, and the intracellular virus titre decreased as well. Our results suggest that O-linked glycosylation on the E2 protein occurred in the post-ER region and the transport of RV structural proteins to the Golgi complex and post-Golgi compartment may be a rate-limiting step in RV assembly and budding.

Angiotensin II and other hypertrophic stimuli mediated by G protein-coupled receptors activate tyrosine kinase, mitogen-activated protein kinase, and 90-kD S6 kinase in cardiac myocytes. The critical role of Ca(2+)-dependent signaling

Many hypertrophic stimuli such as angiotensin II (Ang II) activate phospholipases through G protein-coupled receptors in cardiac myocytes. However, it is not known whether these stimuli also activate the tyrosine phosphorylation-dependent signaling pathway, which plays an essential role in growth factor-induced mitogenic responses in other cell types. Serine/threonine kinases such as mitogen-activated protein (MAP) kinases and 90-kD S6 kinase (RSK) are activated in response to many growth stimuli and are important downstream signaling pathways of tyrosine kinases. Therefore, we examined whether Ang II activates these protein kinases in primary cultures of cardiac myocytes and fibroblasts from neonatal rats. Ang II rapidly induced tyrosine phosphorylation of multiple proteins, including 42-, 44-, 75- to 80-, and 120- to 130-kD proteins, in both cardiac myocytes and fibroblasts. This was accompanied by an increase in tyrosine kinase activity. The 42- and 44-kD proteins were immunologically related to an extracellular signal-regulated kinase family (MAP kinases). Ang II rapidly increased kinase activity of MAP kinases and their downstream kinase, RSK. The Ang II-induced tyrosine phosphorylation and activation of MAP kinases and RSK were AT1 receptor-mediated. Activation of protein kinase C (PKC) by phorbol 12-myristate 13-acetate or an increase in intracellular Ca2+ by the Ca2+ ionophore A23187 was sufficient to cause tyrosine phosphorylation of multiple proteins and activation of MAP kinase and RSK. Although downregulation of PKC did not suppress Ang II-induced activation of MAP kinase and RSK, chelating intracellular Ca2+ by BAPTA-AM completely abolished Ang II-induced activation of these kinases. Activation of MAP kinases and RSK was also observed in myocytes stimulated with other agonists for Gq protein-coupled receptors, such as phenylephrine, norepinephrine, and endothelin 1, but not with agonists to Gs protein-coupled receptors, such as isoproterenol. These results suggest that Ang II and other hypertrophic stimuli, known to act through Gq protein-coupled receptors, rapidly cause tyrosine phosphorylation of several intracellular substrates through activation of tyrosine kinase and activate MAP kinases and RSK in cardiac myocytes as well as in cardiac fibroblasts. Furthermore, intracellular Ca2+, rather than PKC, seems to be critical for Ang II-induced activation of these protein kinases in cardiac myocytes.

Ca2+ handling and myofibrillar Ca2+ sensitivity in ferret cardiac myocytes with pressure-overload hypertrophy

Experiments were performed in aequorin-loaded left ventricular myocytes isolated from hypertrophied hearts and age-matched controls. Five to six months after postvalvular aortic banding, left ventricular hypertrophy was present, as indicated by a 97% (P < 0.001) increase in the left ventricular weight-to-body weight ratio and a 24% (P < 0.001) increase in cell width. In comparison with controls, the hypertrophied myocytes demonstrated that 1) contraction duration was prolonged by 37% (P < 0.001) and was associated with a 44% (P < 0.001) prolongation of the intracellular Ca2+ transient; 2) peak systolic shortening was decreased by 31% (P < 0.001) and was associated with a 21% (P < 0.001) decrease in peak systolic intracellular Ca2+ concentration; 3) both the peak systolic intracellular Ca2+ concentration-to-peak shortening relationship and the intracellular Ca2+ concentration-to-cell shortening relationship at the time of the peak twitch were shifted downward, suggesting a decrease in myofilament Ca2+ responsiveness; and 4) isoproterenol (5 x 10(-8) M) produced equal increases in the peak systolic intracellular Ca2+ of control and hypertrophied myocytes (88 vs. 90%; P > 0.05) in contrast to much smaller increases in the peak cell shortening (170 vs. 73%; P < 0.02) of the hypertrophied myocytes, suggesting a decrease in myofilament Ca2+ responsiveness. These data demonstrate that the hypertrophy-related abnormalities in intracellular Ca2+ handling and mechanical function, previously reported in aequorin-loaded multicellular muscle preparations, are present in isolated myocytes, arguing against changes in the interstitium as essential causative factors.

Expression and characterization of virus-like particles containing rubella virus structural proteins

Rubella virus (RV) virions contain two envelope glycoproteins (E1 and E2) and a capsid protein (C). Noninfectious RV-like particles (VLPs) containing three structural proteins were expressed in a BHK cell line (BHK-24S) by using an inducible promoter. These VLPs were found to resemble RV virons in terms of their size, their morphology, and some biological activities. In immunoblotting studies, VLPs were found to bind similarly to native RV virions with 10 of a panel of 12 RV-specific murine monoclonal antibodies. Immunization of mice with VLPs induced specific antibody responses against RV structural proteins as well as virus-neutralizing and hemagglutination-inhibiting antibodies. After immunization of mice with VLPs, in vitro challenge of isolated lymphocytes with inactivated RV and individual RV structural proteins stimulated proliferation. Our data suggest the possibility of using VLPs as immunogens for serodiagnostic assays and RV vaccines.

Mutational analysis of the arginine residues in the E2-E1 junction region on the proteolytic processing of the polyprotein precursor of rubella virus

Endoproteolytic cleavage of precursors is a key step in biosynthesis of functional proteins. The structural proteins of rubella virus are initially translated as a precursor polyprotein in the order NH2-C-E2-E1-COOH and are cleaved by host signal peptidase to yield three structural proteins. Between regions corresponding to E2 and E1 in the precursor is a region of seven amino acid residues (R-R-A-C-R-R-R) that contains a motif for stop-transfer or a possible target for trypsin-like protease cleavage. Using site-directed mutagenesis, these arginine residues, as well as the signal peptide cleavage site at the N-terminus of E1, have been mutated individually or in combination. Results from in vitro transcription/translation analysis indicated that the mutated E2E1 precursor polyproteins were translocated into the microsome and glycosylated. Expression of mutated precursor polyproteins in COS cells revealed that the cleavage of E2E1 polyprotein precursor was impaired when the signal peptide cleavage site alone or both arginine clusters were altered, whereas partial cleavage was observed in the mutants in which either one of the two arginine clusters was modified. Our data suggest that although the arginine clusters do not function as a basic protease cleavage site, they contribute to maintain the proper configuration of that region for access of cellular signal peptidase.

Differential effects of cocaine and cocaethylene on intracellular Ca2+ and myocardial contraction in cardiac myocytes

1. Isolated cardiac myocytes of the ferret were used to investigate the influence of cocaine and cocaethylene on the intracellular Ca2+ transient indicated by the indo-1 405/480 nm ratio signal, and peak cell shortening. 2. Both cocaine and cocaethylene produced significant decreases in peak intracellular Ca2+ and peak cell shortening in a dose-dependent manner. Of interest, (1) the minimally effective dose of cocaethylene was ten fold lower (10(-8)M versus 10(-7)M) than that of cocaine; (2) the log EC50 of cocaethylene was -5.99 +/- 0.13 (1.0 x 10(-6) M), which was about ten fold lower than that of cocaine (-5.02 +/- 0.11, 9.6 x 10(-6) M); and (3) 1 x 10(-4)M cocaethylene decreased the contraction amplitude by 71 +/- 7%, while the same concentration of cocaine decreased the amplitude only by 55 +/- 5%, indicating that cocaethylene is more potent than cocaine. 3. The negative inotropic effects of either cocaine or cocaethylene could be overcome by noradrenaline (approximately 5 microM) or calcium. 4. In contrast to cocaine, cocaethylene shifted the peak [Ca2+]i-peak shortening relationship downward, indicating that cocaethylene decreased myofilament Ca(2+)-responsiveness. 5. These data indicate that both cocaine and cocaethylene act directly on cardiac myocytes to produce a negative inotropic effect that is due to decreased Ca2+ availability. In contrast to cocaine, cocaethylene produces more potent inhibition by an additional action to decrease myofilament Ca(2+)-responsiveness.

The influence of N-linked glycosylation on the antigenicity and immunogenicity of rubella virus E1 glycoprotein

Rubella virus E1 glycoprotein contains three functional N-linked glycosylation sites. The role of N-linked glycosylation on the antigenicity and immunogenicity of E1 glycoprotein was studied using vaccinia recombinants expressing E1 glycosylation mutants. Expressed E1 glycosylation mutant proteins were recognized by a panel of E1-specific monoclonal antibodies in radioimmunoprecipitation, immunofluorescence, and immunoblotting, indicating that carbohydrate side chains on E1 are not involved in the constitution of epitopes recognized by these monoclonal antibodies. This observation was further supported by the fact that removal of oligosaccharides on E1 by glycosidase digestion did not significantly change the antigenicity of E1. All the glycosylation mutants were capable of eliciting anti-RV E1 antibodies. The single glycosylation mutants (G1, G2, and G3), but not the double mutant (G23) or the triple mutant (G123), were found to be capable of inducing virus neutralizing antibodies. Among the single glycosylation mutants, only G2 and G3 were active in producing hemagglutination inhibition antibodies in mice. Our findings suggest that although carbohydrate on E1 is not directly involved in the antigenic structures of E1, it is important in maintaining proper protein folding and stable conformation for expression of immunological epitopes on E1.

Role of N-linked oligosaccharides in processing and intracellular transport of E2 glycoprotein of rubella virus

The role of N-linked glycosylation in processing and intracellular transport of rubella virus glycoprotein E2 has been studied by expressing glycosylation mutants of E2 in COS cells. A panel of E2 glycosylation mutants were generated by oligonucleotide-directed mutagenesis. Each of the three potential N-linked glycosylation sites was eliminated separately as well as in combination with the other two sites. Expression of the E2 mutant proteins in COS cells indicated that in rubella virus M33 strain, all three sites are used for the addition of N-linked oligosaccharides. Removal of any of the glycosylation sites resulted in slower glycan processing, lower stability, and aberrant disulfide bonding of the mutant proteins, with the severity of defect depending on the number of deleted carbohydrate sites. The mutant proteins were transported to the endoplasmic reticulum and Golgi complex but were not detected on the cell surface. However, the secretion of the anchor-free form of E2 into the medium was not completely blocked by the removal of any one of its glycosylation sites. This effect was dependent on the position of the deleted glycosylation site.

Effects of endothelin on intracellular Ca2+ and contractility in single ventricular myocytes from the ferret and human

We investigated the role of endothelin-1 on peak intracellular Ca2+ ([Ca2+]i) and peak shortening of ventricular myocytes (loaded with indo-1/AM) from failing human hearts. 10 nM of ET-1 significantly increased the cell peak shortening (84 +/- 29%, P less than 0.05) without significantly increasing the peak [Ca2+]i (15 +/- 7%, P greater than 0.05). Further studies on ferret cardiac myocytes indicated that in addition to producing dose-dependent (0.1-10 nM) significant increases in peak shortening (max 55 +/- 6% P less than 0.01) and non-significant increases in peak [Ca2+]i (max 35 +/- 19%, P greater than 0.05), endothelin-1 significantly shifted the peak [Ca2+]i-peak shortening curve upward. The results suggest that endothelin-1 acts directly on human and ferret cardiac myocytes to produce a positive inotropic effect that may predominantly be due to an enhanced myofilament Ca2+ responsiveness.