High and low levels of cottontail rabbit papillomavirus E2 protein generate opposite effects on gene expression

The papillomavirus E2 protein plays an important role in viral transcriptional regulation and replication. We chose to study the cottontail rabbit papillomavirus (CRPV) E2 protein as a transcriptional regulator because of the availability of an animal model for papilloma formation, which may be relevant for human papillomavirus (HPV) infection and replication. We studied the effect of expression levels of E2 on the long control region, which contains transcriptional promoter and enhancer elements, and synthetic E2-dependent artificial promoters in which the E2 was the dominant factor in the transcriptional activation. These experiments indicated that high levels of E2 were inhibitory and low levels were stimulatory for transactivation. In addition, we showed that the complex formed between CRPV E2 and the cognate binding site was less stable than the complex formed between HPV E2 and the same cognate binding site. Furthermore, we showed that CRPV E2 binding to its transcriptional regulatory sequence was stabilized by other proteins such as E1, which produced increments in transcriptional activation of E2-dependent genes. The data may be used to define conditions in which the rabbit model can be used for the screening of drugs which are inhibitory to the HPV and CRPV replication and gene expression.

Selenium, boron, and germanium deficiency in the etiology of Kashin-Beck disease

Concentrations of selenium (Se), boron (B), and germanium (Ge) were determined in scalp hair of children with Kashin-Beck disease (KBD), in healthy children in KBD-disease endemic areas, and in healthy children in non-KBD areas. Mean Se, B, and Ge concentrations were low in children with KBD; in hair of healthy children in KBD areas, Se levels were normal but B and Ge levels were lower than in KBD-free areas. The hair levels of B and Ge were unaffected by selenium supplementation. It is suggested that B and Ge deficiency may be contributing factors in the etiology of KBD.

[Content and activity of the focal adhesion kinase in cultured vascular smooth muscle cells enhanced by urotensin II]

Urotensin II (U II) is the most potent vasoconstrictor identified in vivo, which plays an important role in the smooth muscle cell proliferation in atherosclerosis. All available information suggests that focal adhesion kinase (FAK) is at the crossroads of multiple signaling pathways and is essential for cell proliferation. But the effect of U II on the FAK mediated signal transduction pathway is unclear. In this study, FAK content and tyrosine phosphorylation were assessed by Western blot and immunoprecipitation in cultured rat vascular smooth muscle cells. Increased protein tyrosine phosphorylation was observed within 5 min of U II 10(-7) (mol/L) addition and was maximal by 30 min, while FAK protein content showed no change during the first 30 min but it increased at 2 h reaching a plateau by 4 h, and decreased after 6 h. In addition, the elevated phosphorylation of FAK was detected upon U II stimulation at 10(-8) mol/L, being maximal at 10(-7) mol/L, but decreased at 10(-6) mol/L. Treatment of the cells with cytochalasin B (50 micromol/L), which disrupted the organization of cytoskeleton, had no influence on the increased FAK tyrosine phosphorylation in response to U sti II mulation. In order to study the relationship between FAK and mitogen-activated protein kinase, calmodulin and protein kinase C, selective inhibitors PD98059 (50 micromol/L), W7 (50 micromol/L) and H7 (50 micromol/L) were added following U II treatment. Neither PD98059 nor W7 influenced the increased FAK tyrosine phosphorylation, but H7 further increased it. These findings indicate that FAK activation is independent of the integrity of cytoskeleton and closely related to protein kinase C, but had no relation with mitogen activated protein kinase and calmodulin.

[Quantitative and immunohistochemical analysis of endothelin-1 in oral submucous fibrosis]

OBJECTIVE

This experiment is carried out to investigate roles of endothelin-1 (ET-1), a potent vasoconstrictor and mitogenic peptide, in fibrosis and collagen production.

METHODS

30 cases of oral submucous fibrosis(OSF), 10 cases of oral lichen planus (OLP) and 10 cases of normal control, were studied by means of SABC immunohistochemical method with polyclonal antisera to ET-1 and using image pattern analysis technique.

RESULTS

1. Oral mucosa from OLP and normal control expressed very little ET-1. By contrast, there was striking expression of ET-1 in oral mucosa from OSF; 2. The cellular content of ET-1 in OSF was significantly higher than that in normal control (P < 0.01), while the cellular content of ET-1 in the early and moderate stages OSF were significantly higher than that in the advanced stage(P < 0.01); 3. The cellular content of ET-1 in the early and moderate stages OSF were significantly higher than that in OLP(P < 0.01); 4. There was a significantly positive correlation between cellular contents of epithelia and interstitial(P < 0.05).

CONCLUSION

These findings suggest that cell-specific expression of ET-1 may play a role in pathogenesis of OSF.

[Histochemical study on the nitric oxide synthase in the intestinal myenteric plexus of burned rats]

OBJECTIVE

To elucidate the postburn change in the activity and the distribution of nitric oxide synthase (NOS) in rat intestinal myenteric plexus.

METHODS

The activity and distribution of NOS were quantitatively and locationally studied by histochemical staining with NADPH-diaphorase (NDP), a marker for NOS, and whole mount preparation technique.

RESULTS

NOS was widely distributed in whole intestine wall, especially in myenteric plexus. The majority of NOS positive neurons displayed either round or oval shape. There were some varicosities string of bead-like structure in the nerve fibers and which were accompanied by blood vessels and muscular fibers. There was no significant postburn change in the density of NOS positive neurons in myenteric plexus (P < 0.05). Nevertheless the NOS activity of neurons decreased obviously (P < 0.05 similar 0.01). Meanwhile, it was found after injury that there were indistinction of the structure of NOS positive neuron, more breaking of nerve fibers, leading to the lack of integral web of nerve fibers and obvious decrease of NOS positive varicosities in nerve fibers.

CONCLUSION

After burn injury, the NOS positive neural structure in myenteric plexus of rat small intestine was damaged with the decrease in NOS activity. Simultaneously, there was impairment of the releasing route of nitric oxide (NO). All these changes might be closely related to intestinal structural damage and dysfunction after burn injury.

Evolution of the family of pRN plasmids and their integrase-mediated insertion into the chromosome of the crenarchaeon Sulfolobus solfataricus

Plasmid pHEN7 from Sulfolobus islandicus was sequenced (7.83 kb) and shown to belong to the archaeal pRN family, which includes plasmids pRN1, pRN2, pSSVx and pDL10 that share a large conserved sequence region. pHEN7 is most closely related to pRN1 in this conserved region. It also shares a large variant region containing several homologous genes with pDL10, which is absent from the other plasmids. The variant region is flanked by the sequence motif TTAGAATGGGGATTC and similar duplicated motifs occur in plasmids pRN1 and pRN2, separated by a few bases. It is inferred that recombination at these sites produces the main genetic variability in the plasmid family. The conserved region of the plasmid, and duplicated copies of the motif, are also present in the genome of Sulfolobus solfataricus P2. Moreover, they are bordered by a partitioned integrase gene (int) and by a 45 bp perfect direct repeat corresponding to the downstream half of a tRNA(Val) gene. The integrase and the direct repeat are highly similar in sequence to the integrase and the chromosomal integration site (att), respectively, of the SSV1 virus, which integrates into the chromosome of Sulfolobus shibatae. Recombination at the att repeats in S. solfataricus would produce a novel plasmid, pXQ1, which carries both an intact integrase gene and a single integration site (att). This strongly suggests that the same mechanism of site-specific integration at a tRNA gene is used for both viruses and plasmids in Sulfolobus.

Quantification of the selective retention of palladium octabutoxynaphthalocyanine, a potential photothermal drug, in mouse tissues

Palladium octabutoxynaphthalocyanine (PdNc(OBu)8) is a potential photothermal therapy (PTT) agent, absorbing strongly in the near-infrared region with no ability to induce photodynamic-type sensitisation (unlike many related napthalocyanines). We report here on the application of high pressure liquid chromatography (HPLC) with near-infrared absorption detection for the determination of the tissue accumulation and clearance of PdNc(OBu)8 in a tumour-bearing mouse model (Balb/c mice with EMT6 carcinoma tumour). Due to its insolubility in aqueous-based solvents, the drug was delivered intraperitoneally in a Cremophor-containing vehicle. Good selective accumulation of the drug into the tumour versus muscle or skin is observed, with the best combination of selectivity and tumour concentration occurring at 24-72 h after drug administration. Clearance times are quite long. Comparison with other similar drugs as reported in the literature indicates that the Cremophor-containing vehicle is likely in large part responsible for the observed pharmacokinetic behaviour. This drug shows potential for PTT and will be investigated further for therapy in this animal model.

Morphine enhances interleukin-12 and the production of other pro-inflammatory cytokines in mouse peritoneal macrophages

In this study we investigated the capacity of morphine to modulate expression of cytokines in peritoneal macrophages. Mice were implanted subcutaneously with a 75-mg morphine slow-release pellet, and 48 h later resident peritoneal macrophages were harvested. Control groups received placebo pellets, naltrexone pellets, or morphine plus naltrexone pellets. Adherent cells were stimulated with lipopolysaccharide (LPS: 10 microg/mL) plus interferon-gamma (IFN-gamma: 100 units/mL) to induce cytokine production. After 24 h RNA was extracted for analysis of cytokine mRNA levels by reverse transcriptase-polymerase chain reaction, or supernatants were collected after 48 h for determination of cytokine production by enzyme-linked immunosorbent assay (ELISA). Morphine enhanced mRNA expression of interleukin (IL)-12 p40 and tumor necrosis factor alpha (TNF-alpha) compared with controls, whereas IL-10 levels were unchanged by drug treatment. ELISA data showed that both IL-12 p40 and p70 were increased by morphine. The enhancement of IL-12 at both the mRNA and protein levels was antagonized by naltrexone, indicating that the modulation of this cytokine by morphine is via a classic opioid receptor. These results are particularly interesting in light of our previous observation that 48 h after morphine pellet implantation, the peritoneal cavity is colonized with gram-negative and other enteric bacteria. The enhancement of IL-12 by morphine might be related to morphine-induced sepsis.

DNA vaccination prevents and/or delays carcinoma development of papillomavirus-induced skin papillomas on rabbits

Malignant progression is a life-threatening consequence of human papillomavirus-associated lesions. In this study, we tested the efficacy of papillomavirus early-gene-based vaccines for prevention of carcinoma development of papillomavirus-induced skin papillomas on rabbits. Rabbit skin papillomas were initiated by infection with cottontail rabbit papillomavirus (CRPV). The papillomas were allowed to grow for 3 months without any treatment intervention. Rabbits were then immunized by gene gun-mediated intracutaneous administration of four DNA plasmids encoding CRPV E1, E2, E6, and E7 genes, respectively. All eight control rabbits receiving vector alone developed invasive carcinoma within 8 to 13 months. In contrast, only two of eight vaccinated rabbits developed carcinoma at 12 and 15 months, respectively. Papilloma growth was suppressed in the majority of vaccinated rabbits but not completely eradicated. These results indicate that gene gun-mediated immunization with papillomavirus early genes may be a promising strategy for prevention of malignant progression of human papillomavirus-associated lesions in humans.

In vitro system to study realistic pulsatile flow and stretch signaling in cultured vascular cells

We developed a novel real-time servo-controlled perfusion system that exposes endothelial cells grown in nondistensible or distensible tubes to realistic pulse pressures and phasic shears at physiological mean pressures. A rate-controlled flow pump and linear servo-motor are controlled by digital proportional-integral-derivative feedback that employs previously digitized aortic pressure waves as a command signal. The resulting pressure mirrors the recorded waveform and can be digitally modified to yield any desired mean and pulse pressure amplitude, typically 0-150 mmHg at shears of 0.5-15 dyn/cm(2). The system accurately reproduces the desired arterial pressure waveform and cogenerates physiological flow and shears by the interaction of pressure with the tubing impedance. Rectangular glass capillary tubes [1-mm inside diameter (ID)] are used for real-time fluorescent imaging studies (i. e., pH(i), NO, Ca(2+)), whereas silicon distensible tubes (4-mm ID) are used for more chronic (i.e., 2-24 h) studies regarding signal transduction and gene expression. The latter have an elastic modulus of 12.4. 10(6) dyn/cm(2) similar to in vivo vessels of this size and are studied with the use of a benchtop system. The new approach provides the first in vitro application of realistic mechanical pulsatile forces on vascular cells and should facilitate studies of phasic shear and distension interaction and pulsatile signal transduction.

Factors regulating SCC antigen expression in squamous cell carcinoma of the uterine cervix

Expression of squamous cell carcinoma (SCC) antigen emerged concurrently with squamous formation of the uterine cervix and increased during the neoplastic transformation of the cervical squamous epithelium. SCC antigen expression differed considerably among the histomorphologic cell types of cervical carcinoma. Large cell nonkeratinizing carcinoma contained high levels of the antigen. In contrast, no appreciable expression of SCC antigen was observed in small cell nonkeratinizing carcinoma. The pattern of SCC antigen expression closely coincided with EGF receptor (EGF-R) expression in cervical squamous neoplasia. This suggests that the expression of SCC and EGF-R in cervical carcinoma is related to the differentiation or dedifferentiation processes of the tumor cells. SCC production by CaSki cervical epidermoid carcinoma cells was stimulated by EGF. It seems likely that an autocrine system, in which EGF serves as the signal, may exist in cervical squamous carcinoma. 17beta-estradiol and L-triiodothyronine were found to upregulate EGF-R expression, proliferative potential and SCC production in the CaSki cervical carcinoma cells.

[Studies on Legionella-contamination to the air-conditioning cooling towers in big hotels and on its seroprevalence in the related populations in Beijing]

OBJECTIVE

To understand the situation of Legionella-contamination at cooling towers of big hotel and the level of Legionella-infection among related populations in Beijing.

METHODS

Thirty-eight cooling towers of hotels were chosen for detection of Legionella. Four hundred and fourteen staff members from the hotels were selected as exposure group, with another 414 from general population as controls, for the detection of Legionella antibodies.

RESULTS

Sixteen strains of Legionella pneumophila (Lp) were isolated from 21 of the 38 cooling towers, and the predominant strain was Lp serum group 1 (50%, 8/16). The seroprevalence of Lp antibodies for the exposure group was 9.9% (41/414), comparing to 3.5% (14/414) from the control group. The difference was statistically significant (chi(2) = 14.2, P < 0.01).

CONCLUSION

Legionella was discovered in air-conditioning cooling tower of the hotels, which threatened the health to the population exposed to it.

[IL-8 and IL-10 levels in endometriosis and regulated role of neiyifang on them]

OBJECTIVE

To investigate the IL-8 and IL-10 levels in endometriosis and the regulated role of Neiyifang (NYF) on them.

METHODS

Animal models with endometriosis after Cummings method was established. IL-8 and IL-10 levels were determined in using double antibody sandwich ELISA.

RESULTS

The IL-8 levels of serum and peritoneal fluid, and peritoneal macrophage amounts were markedly higher in the untreated group than those in the control group. The weights of endometriotic tissue and peritoneal macrophage amounts were markedly lower in the treated group of NYF, compared with the untreated group. The lipopolysaccharide stimulated IL-10 secretion in peritoneal macrophages from the untreated group were significantly lower compared with the control group and the treated group of NYF.

CONCLUSION

The abnormality of IL-8 and IL-10 levels in endometriosis may be related to the pathogenesis of the disease. The therapeutical mechanism of NYF was mediated by promotion of IL-10 secretion, and further restrained the composition of inflammatory media and the growth of endometriotic tissue.

[The identification and cloning of human ubiquitin binding enzyme cDNA]

OBJECTIVE

To identify and clone the gene encoding human ubiquitin binding enzyme and study its expression spectrum.

METHODS

According to the sequence of human EST, which is highly homologous to the mouse ubiquitin conjugating enzyme (E2), primers used for library screening were synthesized to screen the human fetal brain cDNA library. The gene was analyzed by making use of bioinformatics and its expression spectrum was studied by using multiple-tissue Northern blot.

RESULTS

Two cDNA clones encoding human ubiquitin conjugating enzyme were isolated and identified. Both containing the ubiquitin conjugating domain, they were 88% identical in amino acid sequences and found to be isoforms of each other with only an exon excised from the short sequence. They belonged to a highly conserved, and widely expressed E2 enzyme family. Northern blot showed that they were expressed exclusively in heart, placenta, and pancreas while no transcripts could be detected in brain, lung, liver, skeletal muscle, or kidney.

CONCLUSIONS

The gene encoding human ubiquitin binding enzyme is expressed under both temporal and spatial control. As a key enzyme in the degradation of proteins, ubiquitin conjugating enzymes play a central role in the expression regulation on the level of post-translation.

[Effects of different nutritional support routes on the intestinal mucosa mucosainjury and renovation in burned rats]

OBJECTIVE

To compare the effects of different nutritional support routes on the intestinal mucosa in burned rats.

METHODS

Wistar rats inflicted with 30% TBSA full thickness burns were employed as the model and randomly divided into three groups: burn with enteral nutrition (EN), burn with parenteral nutrition (PN), and normal control (C). Solutions for intravenous and oral application with same volume, calorie, nitrogen and other nutrients were administered to rats in PN and EN groups, respectively. The plasma diamine oxidase (DAO) activity, the intestinal mucosa change of proliferating cell nuclear antigen (PCNA), of transmembrane electric potential difference (PD), of intestinal trefoil factor and their correlation analysis (ITF) were observed.

RESULTS

Plasma DAO activity increased obviously and PD, PCNA values, ITF content were much lower in EN, PN groups than those in C group. The ITF content, the values of PD and PCNA in EN were much higher than those in PN group, while DAO activity in EN group was obviously lower than that in PN group. In addition, ITF content was significantly negatively correlated to plasma DAO activity, and obviously positively correlated to PCNA and PD values. It is suggested that intestinal mucosa injury was much more severe in PN group than that in EN group.

CONCLUSION

Postburn intestine mucosa mucosal structural injury was related to the evident decrease of synthesis and secretion of ITF. Enteral nutrition might slow down the decrement of ITF, which could explain why EN was superior to PN in terms of decreasing intestinal mucosal injury and enhancing intestinal renovation.

[Blood transfusion, an investigation on its brief history]

Transfusion has developed as a practical clinical technique. Its development has experienced from ignorance to science and from cruelty to civilization for hundreds of year. Transfusion has made great contribution for saving lives and expanding operation coverage. To understand the history of transfusion, we can have reference to promote again the development of transfusion technique.

[Effects of IFN-alpha combined with IL-6 on cell growth and related genes expression and apoptosis of bone marrow cells from CGL patients]

OBJECTIVE

To investigate the effects of interferon-alpha (IFN-alpha) and IFN-alpha combined with interleukin-6 (IL-6) on cell growth and bcr/abl, bcl-2 and c-myc genes expression in the bone marrow mononuclear cells (MNC) from chronic granulocytic leukemia (CGL) patients.

METHODS

MNCs were cultured in liquid medium at the presence of IFN-alpha (200 U/ml) or IFN-alpha (200 U/ml) plus IL-6 (100 ng/ml). The viable cells were counted and the expression levels of beta-actin, bcr/abl, bcl-2 and c-myc genes were quantitatively detected by reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

The cell growth was markedly inhibited by IFN-alpha, but the extent of the inhibition was slightly decreased when IFN-alpha combined with IL-6. The expression levels of bcr/abl and bcl-2 gene were reduced by IFN-alpha or IFN-alpha plus IL-6. The expression of c-myc gene was inhibited by IFN-alpha but promoted by IL-6.

CONCLUSIONS

Both IFN-alpha and IFN-alpha plus IL-6 can inhibit the expression of anti-apoptosis genes, and modulate the expression of c-myc. It is the possible mechanism of IFN-alpha therapy for CGL in chronic phase.

Whole grain foods and heart disease risk

Coronary heart disease (CHD) is the leading cause of death in most developed nations and is rapidly increasing in prevalence in developing countries. Death rates from cardiovascular disease exceed 1 million annually in the United States and account for the largest disease-related cost to health with total costs estimated to exceed $120 billion per annum. Many dietary factors, including total and saturated fat consumption, fruit and vegetable intake and dietary fiber, have been shown to contribute to risk for CHD. We have systematically reviewed literature from the past 20 years evaluating an association between dietary fiber and CHD. Foods that are rich in dietary fiber, including fruits, vegetables, legumes and whole grain cereals, also tend to be a rich source of vitamins, minerals, phytochemicals. antioxidants and other micronutrients. Each of these factors may be independently contributing to the cardiovascular protective effects of fiber-rich foods.

[Influence of monkshood root-peony root combination on inflamation-induced agents and free radicals]

OBJECTIVE

To find out the effect of monkshood root and peony root on inflammation-induced agents and free radicals when used separately and in combination.

METHOD

Two drugs were made into decoctions separately and in combination, i.p., qd, for 7 d, red blood cell SOD and serum LPO were analysed and the anti-inflammatory actions were observed.

RESULTS

In an experimental rat model with inflamed paw edema induced by carrageenin or formaldehyde and in a mouse model with ear swelling induced by xylene, the anti-inflammatory effect appeared stronger when the two drugs were used in combination, especially in comparison with the use of monkshood root alone. The exudation of blood capillaries and the contents of inflammation medium PGE2 were lowered; The activity of SOD extracted from rat or mouse red blood cells was enhanced, and the serum LPO, which was high in level when monkshood root was used alone, could be declined when the two drugs were used in combination.

CONCLUSION

The drug combination is more effective in inhibiting inflammation and scavenging free radicals.

[Effect of Sophora flavescens Ait on cultured beating myocardial cells of coxsackie B3 virus infected newborn rat]

OBJECTIVE

Coxsackie B viruses (CVB3) are considered to be the most common etiologic agents of viral myocarditis. There are not any special anti-CVB3 drugs yet. From previous studies, the anti-CVB3 affect of sophora flavescens ait (SFA) had been discovered. Our experiment was to study the anti-CVB3 ability of SFA to cultured heating myocardial cells of CVB3 infected newborn rat.

METHODS

The myocardial cells were divided into four groups: 1. infected group (n = 8), infected only with CVB3, not adding SFA; 2. treated group (n =8), infected with CVB3, adding SFA (100 microg/ml); 3. drug group (n=6), adding SFA (100 microg/ml) only; 4. control group (n = 6), not infected with CVB3, not adding SFA.

RESULTS

The myocardial cells of the infected group had cell pathogenic effect (CPE) on the second day after virus inoculation, the CPE progressed rapidly from + to ++++. In contrast, no CPE in the other three groups was found. The LDH and SGOT of the infected group were higher than that in the other three groups, showing a significant difference (P <0.05). The virus titer of the infected group was higher than that of the treated group. There was no influence on normal myocardial cells if the concentration of SFA was lower than 300 microg/ml. When the concentration of SFA was 6.25 microg/ml 200 microg/ml, it showed protective effect on infected myocardial cells.

CONCLUSIONS

The results of the experiment suggest that SFA might inhibit CVB3 replication in myocardial cells.

[The expression of cathepsin-D in salivary adenoid cystic carcinoma]

OBJECTIVE

To investigate the relationship between Cathepsin-D(Cath-D) and the prognosis of patients with salivary adenoid cystic carcinoma (SACC).

METHODS

The immunoactivity of Cath-D of 52 cases with SACC was determined by immunohistochemistry method (Streptavidin-Biotin method). The relationship between Cath-D and the histological type, clinical stage, local recurrence, distant metastasis of the tumor and survival rate of the patients with SACC were analysed.

RESULTS

Statistical analysis showed that the expression levels of Cath-D were correlated positively with distant metastasis potential and clinical stage (P < 0.05), and had no significant relation with histological type, local recurrence and survival rate (P > 0.05).

CONCLUSIONS

Cath-D can facilitate invasiveness and distant metastasis of SACC; evaluation of Cath-D can act as a predictor of distant metastasis of SACC and direct the clinical treatment.

[Localization of endothelin-1 in biopsies from oral submucous fibrosis: immunoelectron microscopic study]

OBJECTIVE

To determine the endothelin-1 (ET-1) immunoreactivity in biopsies from human oral submucous fibrosis (OSF) and to investigate the relation between ET-1 and OSF.

METHODS

The localization of ET-1 in biopsies from OSF was observed with immunoelectron microscopic techniques.

RESULTS

High-density deposits existed predominantly in the cytoplasm of epithelial cells, fibroblasts and endothelial cells, but not found in the biopsies of normal controls. In the biopsies of OSF, high-density granules were lined on the cell membrane, possibly on the rough endoplasmic reticulum and the mitochondria of the epithelial cells and of the fibroblasts. But a few granules were seen in the cytoplasm of the endothelial cells of microvesseles.

CONCLUSION

ET-1 is one of the pathogenetic factors of OSF.

Interleukin-4 mediates cell growth inhibition through activation of Stat1

Interleukin-4 (IL-4) activates Stat6 (signal transducer and activator of transcription 6) and plays multiple roles in regulation of the immune system. IL-4 also triggers phosphorylation of insulin receptor substrate (IRS), leading to stimulation of cell growth. Moreover, IL-4 inhibits proliferation of a variety of cells, but the molecular mechanism of its growth inhibitory effect is not understood. In this study, we demonstrated that IL-4 inhibited cell growth of colon carcinoma cell lines (HT29 and WiDr) but promoted cell growth of Burkitt's lymphoma cell lines (BL30 and BL41) in a dose-dependent manner. The growth inhibition was not dependent on Stat6 activation, because Stat6 was activated at similar levels in all cell lines in response to IL-4. Strikingly, IL-4 activated Stat1 in colon carcinoma cell lines but not in Burkitt's lymphoma cell lines. Therefore, these results suggest that IL-4 induced Stat1 activation, resulting in growth inhibition of colon carcinoma cell lines. Importantly, we present evidence that Stat1 is necessary for IL-4-mediated growth inhibition using Stat1-deficient and Stat1-reconstituted cells. The growth inhibitory effect of IL-4 was diminished in Stat1-deficient cells, whereas it was restored in Stat1-reconstituted cells. In addition, the expression of dominant-negative Stat1 in HT29 cells led to the loss of growth inhibition in response to IL-4. Taken together, our data suggest that IL-4 activates Stat1, leading to cell growth inhibition in colon cancer cells. Thus, this study demonstrates, for the first time, a molecular mechanism by which IL-4 inhibits cell growth.

Morphine increases susceptibility to oral Salmonella typhimurium infection

This study examined the effect of morphine on oral infection with virulent Salmonella typhimurium. Animals were treated with a 75-mg slow-release morphine pellet followed by inoculation with salmonellae. Morphine markedly sensitized mice to oral infection, as assessed by survival, mean survival time, and colony culture. By 24 h after Salmonella inoculation, morphine-treated mice had a 105-fold difference in number of organisms in the Peyer's patches, compared with controls. The opioid antagonist naltrexone significantly blocked Salmonella colonization in Peyer's patches and reduced Salmonella burden in other organs, indicating that morphine acts at least in part via an opioid receptor-mediated pathway. The data show that morphine markedly potentiates Salmonella infection at the gastrointestinal portal of entry and enhances subsequent dissemination of Salmonella organisms. The results have implications for potentiating gastrointestinal opportunistic infections in intravenous drug abusers and in opioid-medicated postsurgical patients.