[New method for the isolation of astroglial cells and oligodendrocytes]

Based on the different properties of cellular adhesions, developmental time-courses and growth pattern of astroglial cells and oligodendrocytes, a method of isolating glial cells in vitro was developed. The observations under inverted light microscope and scan electronic microscope identified that the morphology of isolated cells were consistent with the previous description. Immunocytochemical examination showed the expressions of markers, the glial fibrillary acidic protein (GFAP) of astroglia cells and the myelin basic protein (MBP) of oligodendrocytes were consistent with the isolated cells. All parameters showed that the isolated glial cells were pure, and the new methods were easy and reliable.

[A study on ovariectomized goat osteoblast culture in vitro]

Osteoblasts were isolated from the frontal parietal bone of ovariectomized goat and were confirmed by testing for multiple biological features. The results showed that the goat osteoblasts cultured had the typical morphological feature of osteoblasts, the activity of alkaline phosphatase, and the ability of calcification in vitro. Also, the results proved that these goat osteoblasts in vitro had the same function and features as those in vivo. The experimental techniques in this study have provided a useful system for researches in bone metabolism.

Protection of rabbits from viral challenge by gene gun-based intracutaneous vaccination with a combination of cottontail rabbit papillomavirus E1, E2, E6, and E7 genes

In this study, cottontail rabbit papillomavirus infection of domestic rabbits was used as an animal model to develop papillomavirus early gene-based vaccines. Groups of rabbits were intracutaneously vaccinated with single papillomavirus early genes E1, E2, E6, and E7 or with a combination of these four genes. Only a fraction of rabbits were protected from subsequent viral challenge when vaccinated with the E1 or E6 gene. Viral tumor growth in those rabbits vaccinated with the E1 or E2 gene was suppressed compared to that in controls. In contrast, seven of nine rabbits vaccinated with the combination of the E1, E2, E6, and E7 genes were completely protected against viral challenge. These data indicated that intracutaneous genetic vaccination with the combination of the E1, E2, E6, and E7 genes can be an effective strategy for immunoprophylaxis of papillomavirus infection.

[Antihypertensive study of xingnao qingxuan recipe]

OBJECTIVE

To observe the effect of decreasing blood pressure of Xingnao Qingxuan Casuples.

METHOD

The blood pressure in normal and anesthetised cats was examined with direct method, the blood pressure in the conscious SHR was obtained by indirect method.

RESULTS

Duodenuos administration(id) of XQC of 2.8 g/kg produced a decrease of blood pressure in normal cats; XQC of 1.4, 2.8 and 5.6 g/kg once a day for 14 days produced a dose-dependent reduction of blood pressure in SHR, 3-4 days after administration the blood pressure returned to the level before but the change was not significant. With gastric administration of XQC of 2.8 and 5.6 g/kg for 3 times, the incubation period of eyeball tremor induced by chloroform by dropping into the ear was prolonged by 14.4% and 13.0%, and the keeping time shortened by about 33.3% and 23.3% respectively. Brain basic arterial spasm induced by KCl or 5-HT in dog was relaxed obviously by XQC in vitro experiment.

CONCLUSION

XQC has the effect of reducing blood pressure resisting dizziness, which is related to the diastole of brain blood vessel.

[Intestinal blood perfusion improved by early enteral feeding in burned rat]

OBJECTIVE

To explore the mechanism of intestinal blood perfusion improved by early enteral feeding after burn injury.

METHODS

Wistar rats were inflicted with 30% total body surface area full thickness flame burn and randomly divided into three groups: burned control (B), burned and early feeding (EF), and normal control (C). The content of endothelin (ET), nitric oxide (NO), vasoactive intestinal peptide (VIP), and intestine mucosal blood flow (IMBF) were determined at postburn 0, 3, 6, 12, 24, 48 hours.

RESULTS

The content of ET, NO, VIP in small intestine as well as the ratio of ET/NO, ET/VIP were increased significantly and the IMBF was decreased markedly postburn. In EF group, ET, ET/NO and ET/VIP were significantly lower (P < 0.05, P < 0.01), and NO, VIP as well as IMBF were higher than those in B group (P < 0.05, P < 0.01). There were negative correlation between ET/NO, ET/VIP and IMBF (r(1) = -0.95, P < 0.01; r(2) = -0.87, P < 0.01).

CONCLUSIONS

The mechanism of intestinal blood perfusion improved by early enteral feeding may be correlated with increased NO, VIP and decreased ET induced by foods stimulating intestinal nerve.

Development of keratoacanthomas and squamous cell carcinomas in transgenic rabbits with targeted expression of EJras oncogene in epidermis

Activated ras genes have been frequently identified in both benign and malignant human tumors, including keratoacanthoma and squamous cell carcinoma. In this study, we developed two lines of transgenic rabbits in which the expression of EJras has been specifically targeted to the rabbit epidermal keratinocytes, using the upstream regulatory region of cottontail rabbit papillomavirus. All of the F1 transgenic progenies developed multiple keratoacanthomas at about 3 days after birth. The rabbits developed an average of 20 tumors, which usually reached the size of approximately 1 cm in diameter and then spontaneously regressed in about 2 months, similar to keratoacanthoma regression in humans. In addition, up to 18% of the rabbits then developed squamous cell carcinoma at about 5 months of age. The expression of EJras was detectable in all of the keratoacanthomas and squamous cell carcinomas. These results strongly support the involvement of the ras oncogene in both the initiation and regression of keratoacanthoma, and in the development of squamous cell carcinomas. These novel transgenic rabbits, with their consistent tumorigenic phenotype at an early age, high similarity to the human lesions, and easy accessibility for examination, manipulation, biopsy, and treatment, should provide a unique model system for studying ras activation-related tumor initiation, regression, and progression, and for evaluating antitumor therapies.

Growth factors and gene expression in cultured rat hepatocytes

BACKGROUND/AIM

The aim of this study was to evaluate the effect of replication on function variables in cultured hepatocytes.

METHODS

Isolated rat hepatocytes were cultured in HCM medium and plated on collagen-coated dishes at cell densities from 0.2 x 10(5) (subconfluent) to 1.0 x 10(5) x cm(-2) (confluent) with and without addition of hepatocyte growth factor, epidermal growth factor and insulin-like growth factor-I. The synthesis rate was measured for DNA, albumin, urea, and glucose together with mRNA levels (Northern blots) for albumin, urea cycle enzymes, and acute phase and "house-keeping" proteins.

RESULTS

In subconfluent culture the synthesis of DNA and urea was higher (118% and 112%, respectively), and of albumin and glucose lower (40% and 67%, respectively) than in confluent culture. The mRNA levels of carbamoylphosphate synthase, argininosuccinate synthetase, argininosuccinate lyase, arginase, a2-macroglobulin, beta-fibrinogen, and albumin were lower (23%, 58%, 77%, 33%, 12%, 50%, and 51%, respectively) in subconfluent culture compared with confluent culture. Relatively increased levels were found for beta-actin (109%) and alpha-tubulin (136%). In subconfluent culture hepatocyte growth factor increased the DNA synthesis rate 6-fold, epidermal growth factor 3-fold, and insulin-like growth factor-I 2-fold; that of albumin, urea and glucose was not increased significantly. In confluent culture the effect of growth factors on synthesis rates was not significant, and the growth factors had little influence on mRNA levels.

CONCLUSIONS

Hepatocytes produce urea at the same rate in subconfluent as in confluent culture in spite of a lower mRNA level of urea cycle enzymes. Hepatocyte growth factor and epidermal growth factor increase DNA synthesis markedly in subconfluent culture only, without significantly changing the ratio between subconfluent and confluent culture of other variables. This suggests that active replication is not an important cause of the relatively low liver-specific function of hepatocytes in subconfluent culture.

Characterization of the meta-cleavage compound hydrolase gene involved in degradation of the lignin-related biphenyl structure by Sphingomonas paucimobilis SYK-6

Sphingomonas paucimobilis SYK-6 has the ability to transform a lignin-related biphenyl compound, 2,2'-dihydroxy-3,3'-dimethoxy-5, 5'-dicarboxybiphenyl (DDVA), to 5-carboxyvanillic acid (5CVA) via 2, 2',3-trihydroxy-3'-methoxy-5,5'-dicarboxybiphenyl (OH-DDVA). In the 4.9-kb HindIII fragment containing the OH-DDVA meta-cleavage dioxygenase gene (ligZ), we found a novel hydrolase gene (ligY) responsible for the conversion of the meta-cleavage compound of OH-DDVA to 5CVA. Incorporation of 18O from H218O into 5CVA indicated there was a hydrolytic conversion of the OH-DDVA meta-cleavage compound to 5CVA. LigY exhibited hydrolase activity only toward the meta-cleavage compound of OH-DDVA, suggesting its restricted substrate specificity.

[Study on telomerase inhibition by ribozyme targeted to telomerase RNA component]

OBJECTIVE

To evaluate the possibility of using ribozyme technology for telomerase inhibition and cancer therapy.

METHODS

A hammer head ribozyme (telomerase ribozyme, teloRZ) directed against the RNA component of human telomerase (hTR) was designed and synthesized to serve as a telomerase inhibitor. An in vitro transcription plasmid and a eukaryotic expression plasmid containing teloRZ gene were constructed. In vitro cleavage reaction was carried out by mixing the ribozyme RNA with DIG-labeled-hTR in different reaction conditions. Cleavage bands were detected by digoxin chemilumines- cent assay. The eukaryotic expression plasmid was inducted into HeLa cells by lipofectamine; the telomerase activities and bio-characteristics of HeLa cells were detected continuously.

RESULTS

teloRZ showed a specific cleavage activity against the telomerase RNA component used as template. The in vitro cleavage ratio reached about 60%. The telomerase activities of cells expressing teloRZ dropped to eight times; the doubling times became longer and apoptosis ratios became higher with increasing population doublings (PDS); at 19-20 PDS 95% cells showed apoptosis.

CONCLUSION

These findings support the potential use of this ribozyme against immortalized cancer cells.

[Expression of multidrug resistance-associated protein (MRP) and lung resistance protein (LRP) in human rectal carcinomas and its clinical significance]

OBJECTIVE

To investigate the expression and clinical significance of multidrug resistance-associated protein(MRP) and lung resistance protein(LRP) in rectal carcinoma.

METHODS

Fiftyseven paraffin embeded primary rectal carcinoma specimens were examined by immunohistochemical staining.

RESULTS

Of the 57 tumour specimens examined, 28(49.1%) and 24(42.1%) were positively immunostaned for MRP and LRP, respectively. Co-expression of the two proteins was observed in 10(17.5%) specimens. Positive immunostaning of either of the two proteins was not correlated with cell differentiation and Dukes stage (P > 0.05). Patients with MRP-positive tumours had shorter survival than MRP-negative patients (P < 0.05). No such correlation was found for LRP expression, nor was found between MRP and LRP expression.

CONCLUSION

Positive MRP expression in rectal carcinoma appears to be an independant factor of prognostic significance. To examine its expression may help guide rational comprehensive therapy of rectal carcinoma.

Polymeric gadolinium chelate magnetic resonance imaging contrast agents: design, synthesis, and properties

We have synthesized and evaluated five series of polymeric gadolinium chelates which are of interest as potential MRI blood pool contrast agents. The polymers were designed so that important physical properties including molecular weight, relaxivity, metal content, viscosity, and chelate stability could be varied. We have shown that, by selecting polymers of the appropriate MW, extended blood pool retention can be achieved. In addition, relaxivity can be manipulated by changing the polymer rigidity, metal content affected by monomer selection, viscosity by polymer shape, and chelate stability by chelator selection.

[Cross reaction of Trichinella spiralis larva antigens with sera of schistosomiasis japonica]

Cross reactions of T. spiralis muscular larva antigens (TsMLA) against several sera from patients with other parasitic diseases by ELIB (enzyme-linked immunoblotting technique) were studied. The proteins of 31-100 KDa were recognized by sera of two cases of acute schistosomiasis, while proteins of 44/45, 51/53, 62/64 and 100 KDa were recognized by sera of 11 cases of chronic schistosomiasis. The proteins of 60 KDa showed varied cross reactions against sera of five kinds of patients with other parasitic diseases (filariasis, hookworm diseases, paragonimiasis, ascariasis and clonorchiasis). Only the proteins of 45 KDa were recognized by six of fifteen cases of normal human sera. All of > 29 KDa proteins were recognized by sera of rabbit infected by T. spiralis. It is suggested that there were many antigens in Trichinellen muscular larva which shared in common with several other parasites. The cross reactions of TsMLA against Schistosoma japonicum may be differentiated on the positive reaction bands of 44/45, 51/53, 62/64 and 100 KDa proteins which was specific to the chronic schistosomiasis using the TsMLA by means of ELIB.

Mechanisms of growth stimulation by suramin in non-small-cell lung cancer cell lines

PURPOSE

Suramin, a polysulfonated naphthylurea, has been shown to be effective in the treatment of several cancers. We have reported that suramin, at dose concentrations higher than 140 microM, exerts growth-stimulatory effects in several non-small-cell lung cancer (NSCLC) cell lines. The purpose of this study was to examine the mechanisms by which suramin exerts this growth-stimulatory effect in NSCLC cells.

METHODS

NCI-H596 cells were treated with agarose-immobilized suramin, directly or by addition on cell culture inserts, after which growth was determined by [3H]thymidine incorporation. PPADS, a specific purinergic receptor antagonist, was used to determine whether suramin acts via purinergic receptors. The effect of suramin on epidermal growth factor receptor (EGFR) was determined by analyzing receptor phosphorylation and dimerization. XAMR 0721, a suramin analogue containing only one of the two polysulfonated arms, was also analyzed for its effects on growth and EGFR activation.

RESULTS

Agarose-immobilized suramin stimulated NCI-H596 cell growth, but only when added directly to the cells. When the suramin-conjugated beads were added to the cells on cell culture inserts, which preclude an interaction with the cell surface but allow interaction with the culture medium, there was no effect on proliferation. PPADS had no effect on the growth stimulation by suramin; however suramin treatment resulted in rapid phosphorylation and dimerization of EGFR. Treatment with XAMR 0721 did not affect growth or tyrosine phosphorylation and dimerization of EGFR.

CONCLUSIONS

Suramin need not enter NCI-H596 cells to exert its growth-stimulatory effect, nor is this effect mediated by an interaction with soluble growth factors. Rather, it appears that suramin acts via an interaction with EGFR, but not with purinergic receptors.

Interaction of tissue transglutaminase with nuclear transport protein importin-alpha3

Tissue transglutaminase is a multifunctional enzyme which has been involved in the regulation of cell growth, differentiation, and apoptosis. Recently, nuclear localization of tTG has been reported indicating the potential of active nuclear transport. In this study we use the yeast two-hybrid assay and co-immunoprecipitation to show that tTG interacts with the nuclear transport protein importin-alpha3. Using electron microscopy we demonstrate that nuclear expression of tTG in a non-small cell lung cancer cell line is induced by retinoic acid (RA). These data suggest that importin-alpha3 could mediate active nuclear transport of tTG which may be important for the regulation of critical cellular processes.

Detection and sequence analysis of borna disease virus p24 RNA from peripheral blood mononuclear cells of patients with mood disorders or schizophrenia and of blood donors

Borna disease virus (BDV) p24 RNA was detected in the peripheral blood mononuclear cells (PBMCs) of psychiatric patients and blood donors by nested reverse transcriptase PCR (RT-PCR). The prevalences of BDV p24 RNA in patients with mood disorders (4%) and schizophrenia (4%) were not significantly different from that in blood donors (2%). This finding was inconsistent with previous reports that showed either a high prevalence or absence of BDV p24 RNA in patients with psychiatric disorders. The differences in BDV p24 RNA prevalence in these studies may be due to differences in the criteria for positivity, the number of PBMCs used for RNA extraction, or the amount of RNA tested for nested RT-PCR or to laboratory contamination. Sequence analysis of BDV p24 RNA from the PBMCs of patients and blood donors showed a high nucleotide sequence conservation but definite nucleotide mutations compared with horse BDV p24 RNA sequences. In comparison with human BDV p24 RNA sequences previously reported from Japan and Germany, there were several positions with silent nucleotide mutations among these clones.

Effects of anti-IL-4 receptor monoclonal antibody on in vitro T cell cytokine levels: IL-4 production by T cells from non-atopic donors

IL-4 is a pleiotropic cytokine which is involved in the development of atopic diseases. Only limited data exist on IL-4 production in humans, and the relative contribution to atopy of either unbalanced IL-4 production, or increased IL-4-responsiveness of target cells, is still unknown. The use of a MoAb to the IL-4 receptor alpha-chain (IL-4Ralpha) enabled us to demonstrate that IL-4 production in vitro is usually underestimated, due to in vitro consumption, even in cultures of purified T cells. When IL-4 consumption was blocked, it became evident that CD80 and CD86 both provide effective costimulatory signals for high IL-4 production. Moreover, we found that even stimulation with a soluble antigen (tetanus toxoid) induces IL-4 production by T cells from healthy non-atopic donors. Both sets of data imply that IL-4 is not required for IL-4 production by memory and/or effector T cells. Our data further show that endogenous IL-4 activity modulates IL-10 and interferon-gamma production by T cells in opposite directions. The use of this receptor-blocking antibody will thus be helpful for in vitro studies on IL-4 regulation. Consumption of IL-4 by different cell types during in vitro cultures might have interfered with previous attempts to quantify IL-4 production by human T cells.

[Observations on rat's muscle at various postmortem intervals by scanning electron microscopy]

The aim of this study was to observe the morphological changes of muscle in the process of rigor mortis. The quadriceps of 40 rats at various postmortem intervals were observed under the scanning electron microscope (SEM) and the light microscope by phosphtungstic acid-haematoxylin staining. The results showed that the striations of muscle were blurred within 4 hours, but they became apparent from 6 hours to 24 hours after death. The authors suggest that this phenomenon be associated with the increased resistance of muscle against the postmortal changes. The observations by scanning electron microscopy and light microscopy have revealed that the muscles do contract in the process of rigor mortis because the distance between two Z lines shortens and the I band narrows, compared with those in anaesthetised animals. The basic biochemical process for the formation of rigor mortis is the same as that of muscle contraction except that the former happens postmortem and the latter antemortem.

[Investigation of an Legionnaires' disease outbreak associated with contaminated air-conditioning]

An outbreak of upper respiratory infection (influenza-like syndrome) took place among the staff members of a large office building in Beijing, June, 1997. To understand the cause of the outbreak, with a case-control study with serological antibodies detection against serogroup 1 to 14 of Legionnaires' disease bacteria (LDB) and bacteriological test and culture on samples collected from the air-conditioning system of the office building was performed. The findings showed that the attack rates of tonsillitis and upper respiratory infection were 61.86% and 34.62% respectively. The relation was statistically significant between the symptoms of fever and tonsillitis in the cases (chi 2 = 77.88, P < 0.01). The positive rates of LDB antibodies on serogroups 9, 10, 12, 14 were 45.94% in the cases of upper respiratory infection and 3/15, 6/17, 0/15, 1/16 respectively in the four controls groups. Condensied water samples from an air-conditioning system showed that Legionella Pneumophila was positive. Evidence showed that it was an outbreak resulting from LDB serogroup 9 and 12, accompanied by upper respiratory infection related to air-conditioning system contaminated by LDB. This was the first report Lp infection associated with an air-conditioning system in China.

Identification of a membrane-associated inhibitor(s) of epidermal growth factor-induced signal transducer and activator of transcription activation

Many growth factors, including epidermal growth factor (EGF), can activate the signal transducer and activator of transcription (STAT) signaling pathway. Here, we demonstrate that STAT activation by EGF treatment is conditional. EGF activates STAT1 and STAT3 in A431 but not in HeLa and PC12 cells. Using a reconstituted in vitro STAT activation system, we have identified and partially purified a potential inhibitor (s) that is membrane-associated and can block STAT activation induced by EGF in vitro. However, this inhibitor has no effect on STAT complexes after they are formed. We have further shown that this inhibitor(s) also exists in many other cancer cell lines, suggesting that blocking the STAT activation during growth factor signal transduction may play a significant role in the development of many kinds of cancers.

A brief history of diagnostic cytology

Being a discipline specialized for diagnosis of tumors, diagnostic cytology has a history of over 100 years. By exploring the origin, development and its formative process, valuable and special information which are helpful to the general investigation of tumor cases and screening of such patients can be provided.

Cloning of a Sphingomonas paucimobilis SYK-6 gene encoding a novel oxygenase that cleaves lignin-related biphenyl and characterization of the enzyme

Sphingomonas paucimobilis SYK-6 transforms 2,2'-dihydroxy-3,3'-dimethoxy-5,5'-dicarboxybiphenyl (DDVA), a lignin-related biphenyl compound, to 5-carboxyvanillic acid via 2,2',3-trihydroxy-3'-methoxy-5,5'-dicarboxybiphenyl (OH-DDVA) as an intermediate (15). The ring fission of OH-DDVA is an essential step in the DDVA degradative pathway. A 15-kb EcoRI fragment isolated from the cosmid library complemented the growth deficiency of a mutant on OH-DDVA. Subcloning and deletion analysis showed that a 1.4-kb DNA fragment included the gene responsible for the ring fission of OH-DDVA. An open reading frame encoding 334 amino acids was identified and designated ligZ. The deduced amino acid sequence of LigZ had 18 to 21% identity with the class III extradiol dioxygenase family, including the beta subunit (LigB) of protocatechuate 4,5-dioxygenase of SYK-6 (Y. Noda, S. Nishikawa, K.-I. Shiozuka, H. Kadokura, H. Nakajima, K. Yano, Y. Katayama, N. Morohoshi, T. Haraguchi, and M. Yamasaki, J. Bacteriol. 172:2704-2709, 1990), catechol 2,3-dioxygenase I (MpcI) of Alcaligenes eutrophus JMP222 (M. Kabisch and P. Fortnagel, Nucleic Acids Res. 18:3405-3406, 1990), the catalytic subunit of the meta-cleavage enzyme (CarBb) for 2'-aminobiphenyl-2,3-diol from Pseudomonas sp. strain CA10 (S. I. Sato, N. Ouchiyama, T. Kimura, H. Nojiri, H. Yamane, and T. Omori, J. Bacteriol. 179:4841-4849, 1997), and 2,3-dihydroxyphenylpropionate 1,2-dioxygenase (MhpB) of Escherichia coli (E. L. Spence, M. Kawamukai, J. Sanvoisin, H. Braven, and T. D. H. Bugg, J. Bacteriol. 178:5249-5256, 1996). The ring fission product formed from OH-DDVA by LigZ developed a yellow color with an absorption maximum at 455 nm, suggesting meta cleavage. Thus, LigZ was concluded to be a ring cleavage extradiol dioxygenase. LigZ activity was detected only for OH-DDVA and 2,2',3,3'-tetrahydroxy-5,5'-dicarboxybiphenyl and was dependent on the ferrous ion.

[Morphologic changes of red blood cells in various conditions under scanning electron microscope]

To study the changes of RBC in various conditions, blood clots elapsed 6 days in water and air and bloodstains stored in variant time were observed under Scanning Electron Microscope (SEM). The results showed that the morphology of RBC elapsed 6 days in water and air seemed to retain their integrity. They were measured 5, 48-5, 88 microns in diameter, whereas the RBC in the bloodstains stored 14 years were obviously disfigured and some appeared membrane cracking. However, the structure of RBC membrane was well recognized under the SEM. The morphological changes under the SEM and the forensic significance of the RBC were discussed.

Smoking and the development of Warthin's tumour of the parotid gland

The smoking history was surveyed in 160 consecutive patients with Warthin's tumour of the parotid gland in order to investigate the relationship between smoking and the development of this tumour. Two hundred cases of middle-aged or elderly normal persons and 163 consecutive patients with pleomorphic adenoma in the parotid gland served as controls. The percentage of smoking in patients with Warthin's tumour (96.3%) was much higher than that of middle-aged or elderly normal persons (25.5%) and in patients with pleomorphic adenoma (26.4%). Moreover, the amount of smoking was greater and the smoking history was longer in patients with Warthin's tumour. When the male and female patients were analysed respectively, the same result was shown. This case-control study suggests that smoking may be one of the aetiologic factors associated with the development of Warthin's tumour.

Cyclosporin A increases IFN-gamma production by T cells when co-stimulated through CD28

Despite its calcineurin-inhibiting properties, cyclosporin A (CsA) can not inhibit IL-2 production when T cells are co-stimulated by CD80/CD86 on the antigen-presenting cells. We studied the in vitro effect of CsA on IFN-gamma production. Anti-CD3 monoclonal antibody (mAb) was used as the primary stimulus for activation of purified human T cells. A stimulating anti-CD28 mAb, or CD80 or CD86 on stably transfected P815 cells, provided the co-stimulatory signal. IL-2 production was hardly affected by CsA under these stimulating conditions, while IFN-gamma (at the protein and mRNA level) was markedly stimulated by CsA. The use of anti-CD3 or phorbol 12-myristate 13-acetate with ionomycin as the primary stimulus, together with costimulation through either CD28 or CD2 using transfectants with the appropriate ligands, allowed us to demonstrate that the resistance of IFN-gamma production to inhibition by CsA required both CD3 and CD28 triggering. Inhibition of IL-10 production, and to a lesser degree of IL-4 production, by CD4+ cells was responsible for the enhancement of IFN-gamma production in the presence of CsA. In conclusion, IFN-gamma production by CD28-co-stimulated CD4+ T cells is resistant to inhibition by CsA and can even be facilitated by CsA as a result of removing a negative regulatory signal which is mainly IL-10 mediated. This finding might have implications for immunosuppressive strategies based upon the use of CsA.

Serum deprivation-induced apoptosis in cultured porcine granulosa cells is characterized by increased expression of p53 protein, Fas antigen and Fas ligand and by decreased expression of PCNA

Although serum deprivation induces apoptosis in several cell lines, biochemical characterization of the apoptosis in primary granulosa cells (GCs) induced by serum deprivation has rarely been reported. In the present study, GCs from small follicles of porcine ovaries were precultured under a serum-containing condition for seven days, then stepped down to a serum-free condition and cultured for the subsequent two days. GCs were subjected to DNA fragmentation and immunoblot analyses. Data indicated that serum deprivation induced GC apoptosis characterized by DNA laddering, which was associated with decreased expression of proliferating cell nuclear antigen (PCNA) and increased expression of p53 protein, Fas antigen and Fas ligand. Serum deprivation also resulted in an increase in a 115 kDa protein expression despite no detectable expression of a 66 kDa c-myc protein. This suggests that serum removal from primary GCs may activate multiple apoptotic pathways such as a p53-associated pathway and a Fas-Fas ligand pathway.

Pertussis toxin-sensitive G proteins influence nitric oxide synthase III activity and protein levels in rat heart

Inhibitory G protein activity (Gi) and nitric oxide (NO) modulate muscarinic-cholinergic (MC) inhibition of cardiac beta-adrenergic inotropic responses. We hypothesized that Gi mediates MC-NO synthase (NOS) signal transduction. Isoproterenol (0.2-0.8 microg/min) and acetylcholine (1 microM) were administered to isolated perfused rat hearts pretreated with saline (controls; n = 8) or pertussis toxin (PT; 30 microg/kg intraperitoneally 3 d before study; n = 20). PT abrogated in vitro ADP-ribosylation of Gi protein alpha subunit(s) indicating near-total decrease in Gi protein function. Isoproterenol increased peak +dP/dt in both control (peak isoproterenol effect: +2, 589+/-293 mmHg/s, P < 0.0001) and PT hearts (+3,879+/-474 mmHg/s, P < 0.0001). Acetylcholine reversed isoproterenol inotropy in controls (108+/-21% reduction of +dP/dt response, P = 0.001), but had no effect in PT hearts. In controls, NG-monomethyl-L-arginine (100 microM) reduced basal +dP/dt, augmented isoproterenol +dP/dt (peak effect: +4,634+/-690 mmHg/s, P < 0.0001), and reduced the MC inhibitory effect to 69+/-8% (P < 0.03 vs. baseline). L-arginine (100 M) had no effect in controls but in PT hearts decreased basal +dP/dt by 1, 426+/-456 mmHg/s (P < 0.005), downward-shifted the isoproterenol concentration-effect curve, and produced a small MC inhibitory effect (27+/-4% reduction, P < 0.05). This enhanced response to NO substrate was associated with increased NOS III protein abundance, and a three- to fivefold increase in in vitro calcium-dependent NOS activity. Neomycin (1 microM) inhibition of phospholipase C did not reverse L-arginine enhancement of MC inhibitory effects. These data support a primary role for Gi in MC receptor signal transduction with NOS in rat heart, and demonstrate regulatory linkage between Gi and NOS III protein levels.

[Analysis of the major components in cannabis by capillary gas chromatography]

A capillary GC method for the simultaneous determination of cannabidiol (CBD), tetrahydrocannabinol (THC), and cannabinol (CBN) in cannabis is described. The major components in cannabis were extracted with chloroform. After being concentrated by evaporation, the residue was dissolved in methanol. The resulting solution was used for analysis. The conditions for determination were: FID detector, HP-5 capillary column, 10 m x 0.53 mm x 2.65 microns film, column temperature 220 degrees C. The recoveries of the three major components were 97.3%-104.0%(CBD), 97.3%-106.6%(THC) and 95.3%-102.4% (CBN). The coefficients of variation are less than 3%. The limit of detection for the three components was 0.2 mg/L, and their linearity was in the range of 20-120 mg/L. Identification of each component was achieved by comparison of retention times with the standards. This method has the advantages of simplicity, rapidity, sensitivity and accuracy.

[Polymerase chain reaction associated with dig-labelled DNA hybridization of mip gene to identify new isolated Legionella pneumophila strains]

OBJECTIVE

By testing mip gene, one highly conservative virulence gene of Legionella pneumophila (Lp), as targets of polymerase chain reaction (PCR) and Digoxin-labelled probe hybridization to establish a rapid, specific and sensitive gene analysis method that can identify new isolated suspected bacteria strains as Lp.

METHOD

Abstracting all the CDC reference Lp strains' and none-Lp Legionella strains' DNA, as well as the domestic isolated Lp strains' and some non-Legionella control bacteria's DNA as templates, then were processed. All the positive PCR products(if no PCR amplicons were available, the original whole DNA should be detected) were hybridized with Digoxingen-labelled mip gene probe in dot-blot procedure.

RESULT

All the tested Lp strains had positive PCR and hybridization results, at the same time, all none-Legionella bacteria and none-Lp Legionella strains got negative results. 6 of 26 isolates were identified as Lp strains by this method.

CONCLUSION

Such a Lp strain identification procedure shows high specificity and sensitivity (nearly 100%, in this study), and mean-while can be completed in a relative short time. Surely, this method can be largely available and has a potential value in diagnosis of clinical Legionellosis cases and pursuing the pathogen during Legionnaires' disease outbreaks.

IL-12 up-regulates CD40 ligand (CD154) expression on human T cells

IL-12 is a heterodimeric cytokine produced by APC that promotes the development of CD4+ Th1 cells and their IFN-gamma production after TCR/CD3 triggering. We here investigated the capacity of IL-12 to modify the expression on T cells of CD40 ligand (CD40L or CD154), a molecule transiently expressed on activated T cells and known to be of utmost importance for cognate interaction with B cells and for activation of dendritic cells and macrophages. Our data demonstrate that IL-12 up-regulates CD40L expression on anti-CD3-activated human peripheral blood T cells. For optimal induction of CD40L, IL-12 synergizes with IL-2 as well as with other costimulatory interactions, such as B7/CD28. The effect of IL-12 was observed at both the protein and the mRNA level. T cells costimulated by IL-12 provided more efficient help for IL-4-dependent B cell proliferation and for IgG production than when activated in the absence of IL-12. This helper activity was blocked by an mAb against CD40L, indicating that the effect of IL-12 on B cells is mediated indirectly through CD40L. The data thus suggest that the effects of IL-12 on cellular and humoral immune responses are partly mediated through CD40L induction.

[Effects of early enteral feeding on nitric oxide synthase activity in small intestine in burned rat]

OBJECTIVE

Our previous studies have proved that early enteral feeding could improve intestine blood flow after burn injury. But the mechanism was far from being clarified. This study was attempted to explore the effects of early enteral feeding on nitric oxide synthase (NOS) activity in burned rat small intestine and the relationship between the intestine mucosa blood flow (IMBF) and the activity of NOS.

METHODS

The rats were randomly divided into three groups: burned control (B), burned and early enteral feeding (EF), and normal control (C). The activity of NOS including constitute NOS(cNOS) and inducible NOS(iNOS), and the IMBF were determined at postburn 0, 3, 6, 12, 24, 48 hours.

RESULTS

It was found that cNOS activity and IMBF were decreased markedly postburn, and there was positive correlation between cNOS and IMBF (r = 0.97, P < 0.01). But the activity of iNOS, total NOS were increased significantly postburn, they had no correlation to the IMBF. In EF group cNOS activity and the IMBF were significantly higher, the iNOS was obviously lower than that of B group and there was no significant difference of total activity of NOS between two groups.

CONCLUSION

Our results suggested that NOS which is catalyzed from cNOS may play main role in adjusting IMBF. By using early enteral feeding the activity of cNOS is increased and the ischemic state in small intestine is improved after burn injury.

[Application of diode laser in the operation of retinal diseases]

OBJECTIVES

To evaluate the effects of diode laser photocoagulation applied on 43 cases of various kinds of fundus diseases with media opacity and on 40 cases during vitreo-retinal surgery.

METHODS

Indirect ophthalmoscope laser photocoagulator was used for fundus diseases, and endolaser used during surgery.

RESULTS

Vision was improved in 24.7% of the eyes, and was unchanged in 62.9% of the eyes. The neovascularization in proliferative diabetic retinopathy regressed in 78.3% of the eyes. All the retinal holes were closed.

CONCLUSIONS

Diode laser can be used for treatment of some retinal diseases and in the operation. Good results can be obtained in the eyes with some extent of media opacity. No obvious side-effect was observed.

Redefining the separation factor: a potential pathway to a unified separation science

Understanding the separation process in capillary electrophoresis (CE) leads to the unification of the theories for separation science. While the separation of analytes is governed by equilibria in chromatography, and by (centrifugal) field in ultracentrifugation, the separation in CE is governed by both equilibria and (electric) field. Therefore, a comprehensive separation theory that describes the separation process of analytes in CE should be able to describe the separation processes in both chromatography and ultracentrifugation. In this paper, we propose that individual capacity factors for each analyte species be used to describe the migration behavior of an analyte. The effect of field on each analyte species, as well as the effect of equilibria are considered in deriving a generalized equation that is applicable for all separation techniques. The separation factor defined at present does not directly relate to the migration rates of the analytes, and therefore can not be used in a generalized theory. We propose that the ratio of the migration rates of a pair of analytes (gamma) should be used as the separation factor, instead of the ratio of the two capacity factors. When gamma is used to describe the separation of two closely migrating analytes, all separation techniques have the same resolution equation.

Ligation of CD2 provides a strong helper signal for the production of the type 2 cytokines interleukin-4 and -5 by memory T cells

In this study, we investigated the efficiency of costimulatory signaling provided by anti-CD2 monoclonal antibodies (mAbs) for the production of type 1 (IL-2 and IFN-gamma) and type 2 (IL-4, IL-5, and IL-10) cytokines by human T cells. We cultured purified human T cells (freshly isolated from blood) with immobilized anti-CD3 mAb, either alone or in combination with anti-CD28 or anti-CD2 mAbs. When compared with the standard costimulatory signal anti-CD28, anti-CD2 mAbs (9-1 plus 9.6) were shown to be more potent costimulators of IL-4 production and to have similar activity for IL-5 production, but to be less potent for costimulation of IL-2, IL-10, and IFN-gamma production. IL-4 production was completely inhibited by cyclosporin A or by blocking IL-2 activity and its receptor. IL-4 and IL-5 were produced by CD45RO+ T cells but not by CD45RA+ T cells, indicating that anti-CD2 in this system costimulated type 2 cytokine production by differentiated memory cells. In the presence of IL-12, the cytokine profile was shifted to high IFN-gamma and IL-10 production and IL-4 and IL-5 production were slightly inhibited. Our data thus suggest that CD2 ligation plays an important role in the upregulation of Th2-like T cell activity (especially IL-4 production), but they also show that this effect is strongly modulated by IL-12, resulting in predominant IL-10 and IFN-gamma production instead.

Preparation and Organized Assembly of Nanoparticulate TiO2-Stearate Alternating Langmuir-Blodgett Films

Nanoparticulate TiO2-stearate Langmuir-Blodgett-type monolayers and multilayers were directly obtained by using TiO2 hydrosol as the subphase. The surface pressure-versus-surface area isotherms showed that the monolayer could be compressed to a mean molecular area of 0.25 nm2. The monolayer was transferred onto a CaF2 or Si substrate at a dipping speed of 18 cm/min and surface pressure of 25 mN/m. It exhibited Y-type multilayer films over the range investigated (1-30 layers) with a transfer ratio of 1.0 &plusmn; 0.1. FTIR transmission spectra and linear infrared dichroic spectra provided evidence of the formation of a stable organic/inorganic alternating multilayer with nanoparticulate TiO2 between the organic monolayers. There is only slight absorption in the range of the C;equals;O stretching vibration band of the carboxylic group with the 3- and 6-nm TiO2 nanoparticles. This means that TiO2 particles are packed closely; i.e., the surface coverage is very high. A possible structure consists of layers of nanoparticles in close-packed form with two stearate ion layers inbetween. But it can be seen that there are some carboxylic groups (1700 cm-1) not connected to the 20-nm TiO2 nanoparticle. Electron microscopic (TEM) images of TiO2-stearate monolayers show that high-coverage monolayers were obtained when the surface pressure increased to 25 mN/m and the dipping speed to 18 cm/min. Copyright 1997Academic Press

Interleukin 12 and B7/CD28 interaction synergistically upregulate interleukin 10 production by human T cells

Interleukin 12 (IL-12) is a heterodimeric cytokine which promotes the development of Th1 cells and their interferon gamma (IFN-gamma) production after TCR/CD3 triggering. Previous reports indicate that IL-12 synergizes with accessory signalling through B7/CD28 interaction in inducing proliferation and IFN-gamma production by human T cells. In this study, we investigated the capacity of IL-12 to modify cytokine synthesis by freshly purified human peripheral blood T cells stimulated with anti-CD3 as the primary signal and with CD80 on transfected mouse cells as an accessory signal. Our data demonstrate that IL-12 indeed synergizes with B7/CD28 interaction, not only in inducing IFN-gamma production, but also in enhancing IL-10 synthesis in a dose-dependent manner. In contrast, IL-4 and IL-5 production were slightly inhibited by IL-12. The effect of IL-12 on the secretion of IL-10 was confirmed by stimulating T cells in the absence of accessory cells with immobilized anti-CD3 mAb and soluble anti-CD28 mAb. CD80 and IL-12 mainly costimulated CD4+CD45RO+ T cells but not CD8+ or CD45RA+ T cells to produce IL-10. Cyclosporin A (CsA) partially inhibited, and a neutralizing anti-IL-2 mAb in combination with anti-IL-2R mAbs (anti-Tac and Mik beta1) strongly reduced IL-10 production. On the other hand, IL-12 did not affect IL-2 production. The data thus suggest a model in which optimal IL-10 production by stimulated peripheral blood T cells results from the co-operation of IL-12, B7/CD28 interaction and the ensuing IL-2 activity.

Chronic nicotine treatment up-regulates alpha3 and alpha7 acetylcholine receptor subtypes expressed by the human neuroblastoma cell line SH-SY5Y

Chronic exposure to nicotine has been reported to increase the number of nicotinic acetylcholine receptors (AChRs) in brain. The mechanism of up-regulation for the alpha4beta2 AChR subtype, which accounts for the majority of high affinity nicotine binding in mammalian brain, has previously been shown to involve a decrease in the rate of alpha4beta2 AChR turnover. Here, we report an investigation of the extent and mechanism of nicotine-induced up-regulation of alpha3 AChRs and alpha7 AChR subtypes expressed in the human neuroblastoma cell line SH-SY5Y. Up-regulation of human alpha3 AChRs and alpha7 AChRs, unlike alpha4beta2 AChRs, requires much higher nicotine concentrations than are encountered in smokers; the extent of increase of surface AChRs is much less; and the mechanisms of up-regulation are different than with alpha4beta2 AChRs. The mechanisms of up-regulation may be different for alpha3 AChRs or alpha7 AChRs. Chronic treatment with nicotine or carbamylcholine, but not d-tubocurarine, mecamylamine, or dihydro-beta-erythroidine, induced a 500-600% increase in the number of alpha3 AChRs but only a 30% increase in alpha7 AChRs. Chronic nicotine treatment did not increase affinity for nicotine or increase the amount of RNA for alpha3 or alpha7 subunits. The effect of nicotine on up-regulation of alpha7 AChRs was partially blocked by either d-tubocurarine or mecamylamine. The effect of nicotine treatment on the number of alpha3 AChRs was only slightly blocked by the antagonists d-tubocurarine, mecamylamine, or dihydro-beta-erythroidine at concentrations that efficiently block alpha3 AChR function. Most of the nicotine-induced increase in alpha3 AChRs was found to be intracellular. The alpha3 AChRs, which accumulate intracellularly, were shown to have been previously exposed on the cell surface by their susceptibility to antigenic modulation. The data suggest that chronic exposure to nicotine may induce a conformation of cell surface alpha3 AChRs that at least in this cell line are consequently internalized but not immediately destroyed.

Quantitative description of analyte migration behavior based on dynamic complexation in capillary electrophoresis with one or more additives

A comprehensive theory is proposed to describe the migration behavior of analytes in capillary electrophoresis (CE) when one or more additives are present in the buffer solution. This theory amalgamates and extends the previous work done by others. The capacity factor (k') in this theory is defined as the product of the equilibrium constant and the additive concentration, thus, k' changes linearly with additive concentration. The net electrophoretic mobility of an analyte is a function of k', therefore, it can be changed by varying the additive concentration. Three parameters are needed to predict the mobility of an analyte in a one-additive CE system: the mobility of the free analyte, the mobility of the complex, and the equilibrium constant for the analyte-additive interaction (which determines the fraction of the free analyte at different additive concentrations). When additives are used, the change in viscosity obscures this relationship, therefore, a viscosity correction factor is required to convert all mobilities to an ideal state where the viscosity remains constant. The migration behavior of an analyte in a solution with multiple additives can be predicted and controlled, once the equilibrium constants of the interactions between the analyte and each of the additives are obtained separately. beta-Cyclodextrin and hydroxypropyl-beta-cyclodextrin are used as additives and the migration behavior of phenol, p-nitrophenol, and benzoic acid are studied as a model system to verify this theory. When the necessary viscosity correction factor is included, the net electrophoretic mobilities of the analytes obtained from experimental results agree with the values predicted by the theory based on dynamic complexation. Although only experiments with one and two additives were carried out to verify the theory, the equations apply to situations when more than two additives are used. The relationship between the theories of electrophoresis and chromatography is clarified.

Life events and anxiety in Chinese medical students

The authors studied a sample of 537 Chinese medical students aged 15-21 years using Zung's Self-Rating Anxiety Scale (SAS) and a life events checklist. The results showed that test pressure, less free time, peer competition, failure in a test, and financial problems were the most common stressful experiences for medical students during the previous 12 months. Social and personal problems were rated the highest on scores of perceived stress. Of all students, 12.5% scored over the cut-off point on the SAS previously established to indicate risk of psychiatric disorder. Using a stepwise regression analysis, it was shown that poor health status, little physical exercise, financial problems in the family, test pressure, conflict with classmates, the personality trait of introversion, getting up late in the morning, and freshman status were independently associated with the presence of anxiety.

Analysis of west African hunters for foamy virus infections

Foamy viruses are a genus of complex retroviruses that infect a wide variety of mammals. However, a clear association with any disease process has yet to be proven for these viruses. A higher human seroprevalence was reported in African populations, perhaps due to exposure to simian foamy viruses (SFV) endemic in primates. However, the earlier serologic surveys were not confirmed by studies employing nucleic acid amplification. Foamy virus infections of humans clearly do occur as rare zoonoses among primate center or laboratory workers exposed to captive primates or their blood. We sought to detect foamy virus infections in a cohort of humans also presumed to be exposed to SFV, i.e., West African hunters. We constructed recombinant vaccinia viruses that expressed human foamy virus (HFV) Gag or Env polyproteins in mammalian cells. The sera from 17 monkey hunters or several controls were tested in radioimmunoprecipitation assays (RIPAs) against the recombinant HFV proteins. Chimpanzee sera or HFV-positive human sera immunoprecipitated gp130, the HFV Env precursor, as well as p74, the HFV Gag polyprotein. None of the hunters' sera recognized both of these recombinant proteins. We then employed a nested polymerase chain reaction (PCR) analysis of the hunters' DNA but also failed to detect foamy virus infections. Therefore, by utilizing a recombinant RIPA and a nested PCR assay, we have not identified foamy virus infections occurring naturally in hunters exposed to wild monkeys in West Africa.

Immortalization of inbred rabbit keratinocytes from a Shope papilloma and tumorigenic transformation of the cells by EJ-ras

An immortalized cell line of keratinocytes, named SPG1-3, was established from a papilloma induced from cottontail rabbit papillomavirus (CRPV)-infected inbred rabbit skin. The cells have reached 60 passages in culture and are still growing well, but they are not tumorigenic in athymic mice. Although CRPV DNA was present as extrachromosomal episomes in the papilloma from which the cell line was derived from a single colony of keratinocytes, there was no CRPV DNA detectable in the cells. Three sub-cell lines of SPG1-3EJ, SPG1-3EJ1 and SPG1-3EJ2 were then established from the EJ-ras transfected SPG1-3 cells. All of the three sub-lines contained both EJ-ras DNA and a 1.2 kb transcript of EJ-ras, and they are malignantly tumorigenic in athymic mice. These data indicate that CRPV genome and its expression might be essential for the initiation and maintenance of neoplasia, but not for the maintenance of immortalization of the tumor-derived cells. In addition, some oncogenes such as EJ-ras may play an essential role in tumorigenic and malignant conversion of the immortalized cells. These cell lines derived from inbred rabbit skin may provide a useful in vitro system for better understanding of the oncogenic processes of papillomavirus-involved neoplastic progression by transfecting the cells with CRPV genes and serial transplantation to the inbred rabbits for studying host immune responses to the viral oncogenic potential.

Organization of 'nanocrystal molecules' using DNA

Patterning matter on the nanometre scale is an important objective of current materials chemistry and physics. It is driven by both the need to further miniaturize electronic components and the fact that at the nanometre scale, materials properties are strongly size-dependent and thus can be tuned sensitively. In nanoscale crystals, quantum size effects and the large number of surface atoms influence the, chemical, electronic, magnetic and optical behaviour. 'Top-down' (for example, lithographic) methods for nanoscale manipulation reach only to the upper end of the nanometre regime; but whereas 'bottom-up' wet chemical techniques allow for the preparation of mono-disperse, defect-free crystallites just 1-10 nm in size, ways to control the structure of nanocrystal assemblies are scarce. Here we describe a strategy for the synthesis of 'nanocrystal molecules', in which discrete numbers of gold nanocrystals are organized into spatially defined structures based on Watson-Crick base-pairing interactions. We attach single-stranded DNA oligonucleotides of defined length and sequence to individual nanocrystals, and these assemble into dimers and trimers on addition of a complementary single-stranded DNA template. We anticipate that this approach should allow the construction of more complex two- and three-dimensional assemblies.

Assembly of human neuronal nicotinic receptor alpha5 subunits with alpha3, beta2, and beta4 subunits

Nicotinic acetylcholine receptors formed from combinations of alpha3, beta2, beta4, and alpha5 subunits are found in chicken ciliary ganglion neurons and some human neuroblastoma cell lines. We studied the co-expression of various combinations of cloned human alpha3, beta2, beta4, and alpha5 subunits in Xenopus oocytes. Expression on the surface membrane was found only for combinations of alpha3beta2, alpha3beta4, alpha3beta2alpha5, and alpha3beta4alpha5 subunits but not for other combinations of one, two, or three of these subunits. alpha5 subunits assembled inside the oocyte with beta2 but not with alpha3 subunits or other alpha5 subunits. alpha5 subunits coassembled very efficiently with alpha3beta2 or alpha3beta4 combinations. The presence of alpha5 subunits had very little effect on the binding affinities for epibatidine of receptors containing also alpha3 and beta2 or alpha3 and beta4 subunits. The presence of alpha5 subunits increased the rate of desensitization of both receptors containing also alpha3 and beta2 or alpha3 and beta4 subunits. In the case of receptors containing alpha3 and beta4 subunits, the addition of alpha5 subunits had little effect on the responses to acetylcholine or nicotine. However, in the case of receptors containing alpha3 and beta2 subunits, the addition of alpha5 subunits reduced the EC50 for acetylcholine from 28 to 0.5 microM and the EC50 for nicotine from 6.8 to 1.9 microM, while increasing the efficacy of nicotine from 50% on alpha3beta2 receptors to 100% on alpha3beta2alpha5 receptors. Both alpha3beta2 and alpha3beta2alpha5 receptors expressed in oocytes sedimented at the same 11 S value as native alpha3-containing receptors from the human neuroblastoma cell line SH-SY5Y. In the receptors from the neuroblastoma alpha3, beta2, and alpha5 subunits were co-assembled, and 56% of the receptor subtypes containing alpha3 subunits also contained beta2 subunits. The beta2 subunit-containing receptors from SH-SY5Y cells exhibited the high affinity for epibatidine characteristic of receptors formed from alpha3 and beta2 or alpha3, beta2, and alpha5 subunits rather than the low affinity exhibited by receptors formed from alpha3 and beta4 or alpha3, beta4, and alpha5 subunits. Nicotine, like the structurally similar toxin epibatidine, also distinguishes by binding affinity two subtypes of receptors containing alpha3 subunits in SH-SY5Y cells. The affinities of alpha3beta2 receptors expressed in oocytes were similar to the affinities of native alpha3 containing receptors from SH-SY5Y cells for acetylcholine, cytisine, and 1,1-dimethyl-4-phenylpiperazinium.

Accessory signaling by CD40 for T cell activation: induction of Th1 and Th2 cytokines and synergy with interleukin-12 for interferon-gamma production

The interaction of CD40 ligand (CD40L) on activated T cells with CD40 on B cells, monocytes and dendritic cells is essential for humoral immunity and for up-regulation of antigen-presenting cell (APC) functions, as a result of signaling through CD40. There are also some indications that after interaction with CD40, CD40L can directly signal T cells. In this study we demonstrate that upon stimulation of human peripheral blood T cells through the T cell receptor (TCR)/CD3 complex, CD40/CD40L interaction strongly enhances the production of Th1 cytokines such as interleukin (IL)-2 and interferon (IFN)-gamma and Th2 cytokines such as IL-4, IL-5 and IL-10 by a direct effect on T cells. Furthermore, CD40/CD40L interaction synergizes with IL-12 in selectively enhancing IFN-gamma production by purified anti-CD3-stimulated T cells. These effects were observed at both the protein and the mRNA level. Both CD4+ and CD8+ T cells were able to produce IFN-gamma in the presence of helper signals from IL-12 and CD40, although CD8+ T cells were less active. Since CD40/CD40L interaction also up-regulates IL-12 production and B7 expression by APC, our results suggest that CD40/CD40L interaction is bidirectional, and promotes activation of both APC and T cells.