Prevalence of hepatitis G virus RNA in the sera of patients with HIV infection

OBJECTIVE

The routes of transmission of the hepatitis G virus (HGV) are similar to those responsible for infection with HIV. We sought to evaluate the prevalence of HGV RNA in the sera of HIV-infected patients.

METHODS

The sera of 157 HIV-infected patients were assayed by reverse transcriptase-polymerase chain reaction (RT-PCR) using established primers for HGV. Patients were divided into group 1 (positive circulating hepatitis B surface antigen [HBsAg]), group 2 (positive anti-hepatitis C virus [HCV] antibody) and group 3 (without markers for HBV or HCV).

RESULTS

The overall prevalence of HGV RNA was 22%; prevalence was higher in group 1 (49%) than in groups 2 (16%) or 3 (7%). Patients with positive HGV RNA had laboratory values similar to HGV RNA-negative patients except for higher CD4 counts. Patients with an estimated risk duration of < or = 14 years were more likely to be HGV RNA-positive than patients at risk for >15 years. HGV RNA was found as frequently in patients with a homosexual lifestyle as in injection drug users (IDU). Multivariable analysis showed that the presence of HBsAg was the strongest factor associated with the presence of HGV RNA in serum.

CONCLUSIONS

Patients with HIV and HBV coinfection are significantly more likely to be HGV RNA-positive. Patients with a risk factor duration for >15 years were less likely to be HGV RNA-positive, pointing to a decrease in HGV RNA prevalence over time. This study supports the notion that homosexual lifestyle, in addition to injection drug usage and blood product transfusion, is a risk factor for HGV infection.

A method of limited replication for the efficient in vivo delivery of adenovirus to cancer cells

Replication-deficient viral vectors are currently being used in gene transfer strategies to treat cancer cells. Unfortunately, viruses are limited in their ability to diffuse through tissue. This makes it virtually impossible to infect the majority of tumor cells in vivo and results in inadequate gene transfer. This problem can be addressed by allowing limited viral replication. Limited viral replication facilitates greater penetration of virions into tissue and can improve gene transfer. We have developed a strategy of limited viral replication using AdRSVlaclys, a chemically modified E1-deleted adenovirus, to codeliver an exogenous plasmid encoding the adenovirus E1 region. This system allows one round of viral replication. We examined the effect of this limited adenovirus replication in vitro and in vivo. In culture, codelivery of virus and pE1 resulted in a large increase in infected cells when compared with control cells exposed to virus and pUC19. In experiments on nude mice bearing HeLa ascites tumors, intraperitoneal injection of AdRSVlaclys/pE1 resulted in a significantly higher percentage of infected HeLa cells as compared with the PBS controls (p < 0.05) or the AdRSVlaclys/pUC19 controls (p < 0.01). These data demonstrate that the transcomplementation of replication-deficient adenovirus with exogenous E1 DNA leads to limited replication, and this controlled replication enhances gene transfer efficiency of adenovirus in vivo.

Levels of HIV RNA are quantitatively related to prior weight loss in HIV-associated wasting

Thirty-three patients referred to a wasting clinic were evaluated to assess whether levels of HIV RNA were related to the magnitude of prior weight loss. Their median RNA level was 46,887 gene copies/ml (range, <200-510,070 gene copies/ml) at the time of referral. Patients had lost 10.5 +/- 6.4 kg over 461 +/- 304 days. RNA levels were correlated with the absolute amount and percentage of weight lost as well as the difference in body mass index (BMI) at the prior maximal and minimal recorded weights (r = 0.7, 0.67, 0.69; p = .0001 for the comparisons). The magnitude of these changes increased across strata of HIV RNA levels (p < or = .004), previously defined as associated with increasing risk for disease progression. The other parameter that could be associated with weight loss was the CD4 lymphocyte count (r = -0.43; p = .01). Low levels of testosterone and measures of body cell mass, fat free mass, or fat mass within 6 weeks of the RNA level could not be related to weight loss, change in BMI, or RNA levels. Thirty-two of the patients had chronic, relentless weight loss; in 15 of these subjects, no apparent secondary opportunistic complications were associated with weight loss or gastrointestinal symptoms to impair energy intake. Levels of HIV replication appear to be causally related to the magnitude of weight loss in some patients with wasting.

Influence of quantity of lymph-vascular space invasion on the risk of nodal metastases in women with early-stage squamous cancer of the cervix

OBJECTIVE

To determine if the quantity of lymph-vascular space invasion influences the risk of pelvic nodal metastases in women with early-stage cervical squamous carcinoma.

METHODS

Between 1991 and 1997, 105 women with stages IA2, Ib, and IIa squamous carcinoma of the cervix underwent radical hysterectomy and pelvic lymphadenectomy. The histopathology slides were prospectively reviewed. If lymph-vascular space invasion (LVSI) was present, the amount was quantified in four ways: percentage of cervical histopathologic sections containing LVSI, percentage of sections with tumor containing LVSI, total number of foci of LVSI, and maximal number of foci of LVSI in 10 high-powered fields. These measures of LVSI were correlated with the risk of nodal metastases.

RESULTS

Seventy-three (70%) women had tumors with LVSI. Of these, 23 had pelvic nodal metastases. All women with nodal metastases had tumors with LVSI. Using logistic regession, independent predictors of nodal metastases were depth of cervical stromal invasion (P = 0.01) and tumor size (P = 0.04). LVSI was also a significant predictor of nodal metastases based on the Mantel-Haenszel test (P = 0.01). In women whose tumors contained LVSI, logistic regression identified tumor size (P = 0.004) and LVSI in > 45% of all cervical histopathologic sections (P = 0.002) as significant predictors of nodal metastases.

CONCLUSION

The quantity of LVSI, as defined by the percentage of all cervical histopathologic sections containing LVSI, correlates significantly with the risk of nodal metastases in women with early-stage squamous carcinoma of the cervix.

A pilot randomized, controlled trial of the effect of iron depletion on long-term response to alpha-interferon in patients with chronic hepatitis C

BACKGROUND/AIMS

Some studies have suggested that hepatic iron may influence the response to interferon therapy in chronic hepatitis C patients. We conducted this randomized, controlled trial to evaluate the effect of iron depletion on: (1) aminotransferase activity and hepatitis C RNA levels; and (2) response to interferon therapy in 38 patients with elevated alanine aminotransferase levels and who were HCV RNA positive.

METHODS

Seventeen patients underwent a 500-ml phlebotomy every 2 weeks until iron deficiency was achieved. Patients were then started on a 6-month course of alpha-interferon 2b (3 mu tiw). Controls were 21 patients who were monitored for a 6- to 8-week period without phlebotomy prior to interferon therapy. Response to interferon was defined as loss of serum HCV RNA by reverse transcriptase-polymerase chain reaction. Serum HCV RNA was quantitated by bDNA technique.

RESULTS

Alanine aminotransferase levels decreased in 15/17 patients after phlebotomy. Mean alanine aminotransferase fell from 156.8 to 89.7 U/l (p=0.008). Changes in iron indices and alanine aminotransferase after phlebotomy were not accompanied by changes in HCV RNA levels. In control patients, neither alanine aminotransferase nor HCV RNA levels changed during the observation period. At the end of 24 weeks of interferon therapy, 7/17 phlebotomized patients had a response, compared to 6/21 control patients (p=ns). After 6 months of follow-up, 5/17 phlebotomized patients remained HCV RNA negative, in contrast to only 1/21 controls (p=0.07).

CONCLUSIONS

Iron depletion led to a reduction in aminotransferase levels; this was not accompanied by changes in levels of hepatitis C RNA. There may be an improvement in the sustained response to interferon therapy, but this requires confirmation.

Risk of residual invasive disease in women with microinvasive squamous cancer in a conization specimen

OBJECTIVE

To quantify the risk of residual invasion when cervical conization reveals microinvasive squamous carcinoma and to determine whether any factors affect this risk.

METHODS

We reviewed the charts and histopathology slides of 87 women who underwent a conization that contained microinvasive squamous carcinoma, followed by either a repeat conization or hysterectomy. Depth of invasion, number of invasive foci, and status of the internal margin and post-conization endocervical curettage (ECC) were assessed. The findings were correlated with the presence of residual invasion.

RESULTS

Significant predictors of residual invasion included status of the internal margin (residual invasion present in 22% of women with an involved margin versus 3% with a negative margin; P < .03) and the combined status of the internal margin and post-conization ECC (residual invasion in 4% of patients if both negative, 13% if one positive, and 33% if both positive; P < .015). Depth of invasion and number of invasive foci in the conization specimen were not significant. The power of this study to detect a 25% difference in the risk of residual invasion was 73% for depth of invasion and 75% for number of invasive foci.

CONCLUSION

Women with microinvasive squamous carcinoma in a conization specimen in which both the internal conization margin and post-conization ECC are negative have a low risk of residual invasion and are candidates for follow-up or simple hysterectomy. If either the internal margin or the post-conization ECC contains dysplasia or carcinoma, the risk of residual invasion is high and warrants repeat conization before definitive treatment planning.

Developmental and environmental regulation of tissue- and cell-specific expression for a pea protein farnesyltransferase gene in transgenic plants

Farnesylation mediates membrane targeting and in vivo activities of several key regulatory proteins such as Ras and Ras-related GTPases and protein kinases in yeast and mammals, and is implicated in cell cycle control and abscisic acid (ABA) signaling in plants. In this study, the developmental expression of a pea protein farnesyltransferase (FTase) gene was examined using transgenic expression of the beta-glucuronidase (GUS) gene fused to a 3.2 kb 5' upstream sequence of the gene encoding the pea FTase beta subunit. Coordinate expression of the GUS transgene and endogenous tobacco FTase beta subunit gene in tobacco cell lines suggests that the 3.2 kb region contains the key FTase promoter elements. In transgenic tobacco plants, GUS expression is most prominent in meristematic tissues such as root tips, lateral root primordia and the shoot apex, supporting a role for FTase in the control of the cell cycle in plants. GUS activity was also detected in mature embryos and imbibed embryos, in accordance with a role for FTase in ABA signaling that modulates seed dormancy and germination. In addition, GUS activity was detected in regions that border two organs, e.g. junctions between stems and leaf petioles, cotyledons and hypocotyls, roots and hypocotyls, and primary and secondary roots. GUS is expressed in phloem complexes that are adjacent to actively growing tissues such as young leaves, roots of light-grown seedlings, and hypocotyls of dark-grown seedlings. Both light and sugar (e.g. sucrose) treatments repressed GUS expression in dark-grown seedlings. These expression patterns suggest a potential involvement of FTase in the regulation of nutrient allocation into actively growing tissues.

Clinical correlates of interferon gamma production in patients with tuberculosis

To determine if the capacity to produce interferon (IFN) gamma is related to the clinical manifestations of tuberculosis, we correlated Mycobacterium tuberculosis-induced IFN-gamma production by peripheral blood mononuclear cells (PBMCs) with clinical, radiographic, and laboratory variables for 63 human immunodeficiency virus (HIV)-negative patients and 43 HIV-positive patients with tuberculosis. For HIV-negative patients whose chest radiographs showed moderately advanced disease, the mean IFN-gamma concentration +/- SD was 1,639 +/- 388 pg/mL, whereas that for patients with far-advanced disease was 327 +/- 100 pg/mL (P = .0001). For HIV-infected patients who had only pleuropulmonary disease, the mean IFN-gamma concentration was 1,002 +/- 257 pg/mL, whereas that for patients with disease outside the lungs and pleura was 149 +/- 55 pg/mL (P = .0004). Multivariate analysis confirmed that the radiographic extent of disease and the site of disease were the only independent predictors of IFN-gamma production in HIV-negative and HIV-infected patients (P < or = .001). We conclude that reduced IFN-gamma production by PBMCs is a marker of severe tuberculosis in both HIV-negative and HIV-infected patients with tuberculosis.

Carboplatin as a radiation sensitizer in locally advanced cervical cancer: a pilot study

Radiation therapy is the mainstay in treatment of locally advanced cervical carcinoma. Several chemotherapeutic agents have been used as radiation sensitizers in the treatment of cervical cancer in an effort to improve local response and survival. A prospective study was designed to evaluate carboplatin as a radiosensitizer in advanced cervical cancer. Standard radiotherapy techniques were used to treat patients with Stage IIA-IIIB cervical cancer. Intravenous carboplatin was administered twice weekly concurrent with external beam radiation. Of 22 evaluable patients, there were 19 complete responders of whom 15 remain alive: 11 patients were alive and disease free at last visit for a median duration of 15 months follow-up (range, 4-43 months) and 4 patients remain alive with disease for a median duration of 17 months (range, 3-55 months). Seven have died, one of whom was without evidence of disease. There were no treatment-related deaths and no grade 4 toxicity. The most significant adverse effect was hematologic resulting in four patients with grade 3 neutropenia or anemia. There were no fistulae or late gastrointestinal or genitourinary complications. This pilot study suggests that carboplatin administered with standard radiation is safe, well-tolerated, and thus may be useful as a radiation sensitizer in the treatment of locally advanced cervical cancer.

CD4 cell counts in human immunodeficiency virus-negative patients with tuberculosis

We evaluated 85 human immunodeficiency virus (HIV)-negative patients with tuberculosis for clinical features and CD4 cell counts. Thirty-seven patients had low CD4 cell counts (mean +/- SD, 341 +/- 116 cells/microL), and 48 patients had normal CD4 cell counts (mean +/- SD, 830 +/- 254 cells/microL). CD4 cell counts were most strongly correlated with total lymphocyte counts (r = 0.84). If total lymphocyte count was excluded, depressed CD4 cell counts were significantly associated with low serum albumin levels, extensive pulmonary disease, low body-mass index, and low hematocrit. Of these four variables, multivariate linear discriminant analysis revealed that the serum albumin level was the best single predictor of low CD4 cell counts and that the other three variables did not improve predictive value. Because these four variables are markers of severe tuberculosis, these findings suggest that disease severity is associated with greater depression of the total lymphocyte and CD4 cell counts. The CD4 cell counts returned to normal levels in most patients after 1 month of therapy.

Tyrosine phosphorylation of Pyk2 is selectively regulated by Fyn during TCR signaling

The Src family protein tyrosine kinases (PTKs), Lck and Fyn, are coexpressed in T cells and perform crucial functions involved in the initiation of T cell antigen receptor (TCR) signal transduction. However, the mechanisms by which Lck and Fyn regulate TCR signaling are still not completely understood. One important question is whether Lck and Fyn have specific targets or only provide functional redundancy during TCR signaling. We have previously shown that Lck plays a major role in the tyrosine phosphorylation of the TCR-zeta chain and the ZAP-70 PTK. In an effort to identify the targets that are specifically regulated by Fyn, we have studied the tyrosine phosphorylation of Pyk2, a recently discovered new member of the focal adhesion kinase family PTK. We demonstrated that Pyk2 was rapidly tyrosine phosphorylated following TCR stimulation. TCR-induced tyrosine phosphorylation of Pyk2 was selectively dependent on Fyn but not Lck. Moreover, in heterologous COS-7 cells, coexpression of Pyk2 with Fyn but not Lck resulted in substantial increases in Pyk2 tyrosine phosphorylation. The selective regulation of Pyk2 tyrosine phosphorylation by Fyn in vivo correlated with the preferential phosphorylation of Pyk2 by Fyn in vitro. Our results demonstrate that Pyk2 is a specific target regulated by Fyn during TCR signaling.

T cell antigen receptor signal transduction

The T cell antigen receptor (TCR) initiates signal transduction by activating multiple cytoplasmic protein tyrosine kinases (PTKs). Considerable progress in the field of TCR signal transduction has been made in three areas recently: first, in understanding the structure and function of the PTK ZAP-70; second, in the elucidation of the function of the substrates and pathways downstream of the PTKs; and third, in the identification of molecules that negatively regulate TCR signalling.

Protein farnesyltransferase in plants: molecular characterization and involvement in cell cycle control

Farnesylation is required for membrane targeting, protein-protein interactions, and the biological activity of key regulatory proteins, such as Ras small GTPases and protein kinases in a wide range of eukaryotes. In this report, we describe the molecular identification of a plant protein farnesyltransferase (FTase) and evidence for its role in the control of the cell cycle in plants. A pea gene encoding a homolog of the FTase beta subunit was previously cloned using a polymerase chain reaction-based strategy. A similar approach was used to clone a pea gene encoding a homolog of the FTase alpha subunit. The biochemical function of the pea FTase homologs was demonstrated by the reconstitution of FTase enzyme activity using FTase fusion proteins coexpressed in Escherichia coll. RNA gel blot analyses showed that levels of FTase mRNAs are generally higher in tissues, such as those of nodules, that are active in cell division. The relationship of FTase to cell division was further analyzed during the growth of suspension-cultured tobacco BY-2 cells. A biphasic fluctuation of FTase enzyme activity preceded corresponding changes in mitotic activity at the early log phase of cell growth. Moreover, manumycin, a specific inhibitor of FTase, was effective in inhibiting mitosis and growth in these cells. Using synchronized BY-2 cells, manumycin completely blocked mitosis when added at the early S phase but not when added at the G2 phase. These data suggest that FTase is required for the plant cell cycle, perhaps by modulating the progression through the S phase and the transition from G1 to the S phase.

Effect of supplementary antioxidant vitamin intake on carotid arterial wall intima-media thickness in a controlled clinical trial of cholesterol lowering

BACKGROUND

There is accumulating experimental, epidemiological, and clinical evidence of an association between anti-oxidant vitamin intake and reduced risk of coronary heart disease. Using data from the Cholesterol Lowering Atherosclerosis Study (CLAS), we explored the association of self-selected supplementary antioxidant vitamin intake on the rate of progression of early preintrusive atherosclerosis.

METHODS AND RESULTS

CLAS was an arterial imaging trial in which nonsmoking 40- to 59-year-old men with previous coronary artery bypass graft surgery were randomized to colestipol/niacin plus diet or placebo plus diet. The rate of progression of early preintrusive atherosclerosis was determined in 146 subjects using high-resolution B-mode ultrasound quantification of the distal common carotid artery far wall intima-media thickness (IMT). From the nutritional supplement database, 22 subjects had an on-trial average supplementary vitamin E intake of > or = 100 IU per day (high users) and 29 subjects had an average on-trial supplementary vitamin C intake of > or = 250 mg per day (high users). Within the placebo group, less carotid IMT progression was found for high supplementary vitamin E users when compared with low vitamin E users (0.008 versus 0.023 mm/y, P = .03). No effect of vitamin E within the drug group was found. No effect of vitamin C within the drug or placebo group was found.

CONCLUSIONS

Supplementary vitamin E intake appears to be effective in reducing the progression of atherosclerosis in subjects not treated with lipid-lowering drugs while the process is still confined to the arterial wall (early preintrusive atherosclerosis).

TCR-gamma delta cells in CD3 zeta-deficient mice contain Fc epsilon RI gamma in the receptor complex but are specifically unresponsive to antigen

Unlike TCR-alpha beta cells, TCR-gamma delta cells express a distinct member of the zeta family, the gamma-chain of Fc epsilon RI (Fc epsilon RI gamma) within the TCR complex. To study the role of the Fc epsilon RI gamma-chain in TCR-gamma delta cells, a TCR-gamma delta transgenic mouse (G8) has been crossed with CD3 zeta-chain-deficient mice (G8.zeta-/-). Thy-1+ spleen and lymph node cells of these animals expressed low levels of CD3/TCR. These results suggested that the zeta-chain is required for effective TCR transport to the cell surface. In contrast, intraepithelial TCR-gamma delta cells of G8.zeta-/- mice expressed high levels of TCR. Immunoprecipitation with anti-CD3 showed that Fc epsilon RI gamma-chains were associated with the TCR complex in T cells isolated from zeta-deficient mice. Although the Fc epsilon RI gamma-expressing T cells proliferated in response to stimulation by TCR-specific Abs including anti-CD3 epsilon, anti-pan gamma delta, and anti-V gamma 2 mAb, the G8.zeta-/- T cells did not respond to the G8-specific Ag (T10b), anti-Thy-1 mAb, or Con A. The unresponsiveness to the Ag was not due to the reduced TCR expression, because intraepithelial TCR-gamma delta cells from the zeta-deficient mice did not respond to Ag. The inability of the G8.zeta-/- T cells to respond to Ag could not be overcome by providing an anti-CD28 costimulatory signal or by adding exogenous rIL-2. Taken together, our data suggest that the Fc epsilon RI gamma-chain associates with the TCR-gamma delta complex in the absence of the zeta-chain, but it is not able to substitute for the zeta-chain for effective transport of TCR to the cell surface or functional responses to Ag.

TCR-gamma delta cells in CD3 zeta-deficient mice contain Fc epsilon RI gamma in the receptor complex but are specifically unresponsive to antigen

Unlike TCR-alpha beta cells, TCR-gamma delta cells express a distinct member of the zeta family, the gamma-chain of Fc epsilon RI (Fc epsilon RI gamma) within the TCR complex. To study the role of the Fc epsilon RI gamma-chain in TCR-gamma delta cells, a TCR-gamma delta transgenic mouse (G8) has been crossed with CD3 zeta-chain-deficient mice (G8.zeta-/-). Thy-1+ spleen and lymph node cells of these animals expressed low levels of CD3/TCR. These results suggested that the zeta-chain is required for effective TCR transport to the cell surface. In contrast, intraepithelial TCR-gamma delta cells of G8.zeta-/- mice expressed high levels of TCR. Immunoprecipitation with anti-CD3 showed that Fc epsilon RI gamma-chains were associated with the TCR complex in T cells isolated from zeta-deficient mice. Although the Fc epsilon RI gamma-expressing T cells proliferated in response to stimulation by TCR-specific Abs including anti-CD3 epsilon, anti-pan gamma delta, and anti-V gamma 2 mAb, the G8.zeta-/- T cells did not respond to the G8-specific Ag (T10b), anti-Thy-1 mAb, or Con A. The unresponsiveness to the Ag was not due to the reduced TCR expression, because intraepithelial TCR-gamma delta cells from the zeta-deficient mice did not respond to Ag. The inability of the G8.zeta-/- T cells to respond to Ag could not be overcome by providing an anti-CD28 costimulatory signal or by adding exogenous rIL-2. Taken together, our data suggest that the Fc epsilon RI gamma-chain associates with the TCR-gamma delta complex in the absence of the zeta-chain, but it is not able to substitute for the zeta-chain for effective transport of TCR to the cell surface or functional responses to Ag.

The prognostic utility of the Silicone Study Classification System. Silicone Study Report 9. Silicone Study Group

OBJECTIVE

To evaluate the reproducibility and the prognostic utility of the Retina Society and Silicone Study Classification Systems in eyes after surgery for severe proliferative vitreoretinopathy (PVR).

DESIGN

Subgroup analysis of the Silicone Study--a randomized, multicentered, surgical trial.

SETTING

Community and university-based ophthalmology clinics.

MATERIALS

Three hundred forty eyes with preoperative and intraoperative evaluations using both systems of grading PVR (reproducibility study), and 287 eyes with preoperative and intraoperative evaluations using both systems of grading PVR and with a 24-month follow-up examination (prognosis study).

INTERVENTIONS

Vitrectomy for PVR with long-acting perfluoropropane gas or silicone oil as the intraocular tamponade.

OUTCOME MEASURES

Retinal reattachment, visual acuity ( > or = 5/200), intraocular pressure, corneal clarity, and the need for reoperation.

RESULTS

The reproducibility of the Silicone Study Classification System was 64% (type of contraction), 77% (number of clock hours), 67% (posterior PVR), 88% anterior and posterior PVR), and 94% (anterior, posterior, and subretinal PVR). The reproducibility of the Retina Society Classification System was 99%. Using the Silicone Study Classification System, location of PVR predicted visual acuity (P=.004, chi 2 test for trend) and hypotony (P=.03, chi 2 test for trend). Using the Retina Society Classification System, the grade of PVR predicted only visual acuity (P=.01, chi 2 test for trend). For eyes with anterior and posterior PVR, there was a decreasing trend in successful visual acuity outcome with increasing severity of PVR (from C-3 to D-3, P=.02, chi 2 test for trend).

CONCLUSIONS

Although the classification of PVR using the Silicone Study classification System was not reproducible for the type of contraction or for posterior PVR, identification of the anteroposterior extent of the PVR was prognostic of visual acuity and hypotony at 24 months. The joint knowledge of the location of PVR (using the Silicone Study Classification System) and the tightness of the funnel for retinas with 9 to 12 clock hours involved by fixed folds (using the Retina Society Classification System) has prognostic utility for eyes with anterior and posterior PVR.

Dominant-negative zeta-associated protein 70 inhibits T cell antigen receptor signaling

Zeta-associated protein (ZAP)-70 is a cytoplasmic protein tyrosine required for T cell antigen receptor (TCR) signaling and development. Mutations in ZAP-70 result in severe combined immunodeficiency in humans. ZAP-70 interacts with the TCR by binding to tyrosine-phosphorylated immunoreceptor tyrosine-based activation motifs (ITAMs) present in the invariant subunits of the TCR complex. Here we report that two ZAP-70 mutants devoid of kinase activity, generated either by a point mutation in the kinase domain to create an inactive kinase, or by truncation of the entire kinase domain (SH2[N+C]), functioned as dominant-negative mutants to specifically suppress TCR-mediated activation of NFAT, a nuclear factor essential for inducible interleukin 2 gene expression. Biochemical studies with the SH2(N+C) mutant showed that it also blocked early TCR signaling events, such as p95vav tyrosine phosphorylation, extracellular signal-regulated kinase 2 activation, and the association of a number of tyrosine-phosphorylated proteins with growth factor receptor-binding protein 2 (GRB2). The inhibitory effects of the SH2(N+C) mutant revealed that it requires an intact phosphotyrosine-binding site in its COOH-terminal SH2 domain. Using a CD8-zeta chimeric receptor to analyze the interaction of the SH2(N+C) mutant with ITAMs of TCR-zeta, we found that this mutant was constitutively bound to the hyperphosphorylated CD8-zeta chimera. These results indicate that tyrosine-phosphorylated ITAM is the target for the action of this dominant-negative mutant, suggesting that the assembly of a functional receptor signaling complex on ITAMs is a critical proximal TCR signaling event leading to downstream activation.

Administration of Escherichia coli endotoxin to rat increases liver mass and hepatocyte volume in vivo

We have established, in vivo, an increase in liver mass and hepatocyte volume after a single intraperitoneal administration, to fasted rats, of Escherichia coli lipopolysaccharide (0127:B8) at 3 mg/kg. The phenomenon was time- and dose-dependent and could be prevented by treatment with polyclonal antiserum against tumour necrosis factor-alpha (TNF-alpha) before the endotoxin injection. Endotoxin caused an increase of 26% in the hepatic mass compared with fasted controls at 24 h. An increase of 27% in the hepatic water content underlay the altered hepatic mass which could not be accounted for by a change in the volume of hepatic blood and/or interstitial fluid (measured in vivo), suggesting an expansion in the hepatocellular volume. This is supported by an increase of 25% in the K+ content of the endotoxic livers. Morphometric study confirmed a 15% increase in hepatocyte volume after endotoxin administration. The data are discussed in the light of possible metabolic effects of increased hepatocyte volume.

[Serogroups, virulence and hemolytic activity of Aeromon as hydrophila which caused fish bacterial septicaemia]

A new infected disease called bacterial septicaemia occurred in cyprinid fish throughout China during 1989-1992. A. hydrophila was known as the most important pathogen of this harmful disease. Thirty-three strains of A. hydrophila, most isolated from moribund fishes, were serogrouped by tube-agglutination with rabbit antisera. Most of the isolates could be grouped into two serotypes, TPS-30 and PBJS-76. These two groups could be found not only in Zhejiang province but in other province in south China. It can be concluded that the two serogroups were the main Aeromonas groups caused this fish disease. These isolates were virulent to Carassius auratus, with LD50 values of 10(4) to 10(6). The hemolytic activity ranged from titers of 1/8 to 1/16. No relationship were observed with the hemolytic activity and virulence.

Activation of hepatic glutaminase in the endotoxin-treated rat

The basis for the accelerated hepatic utilization of glutamine that occurs during endotoxemia was investigated. In rats treated with Escherichia coli lipopolysaccharide, glutaminase activity, measured in membranes of freezed-thawed liver mitochondria, was unchanged compared with that of controls. However, flux through glutaminase in intact mitochondria was increased more than 3.5-fold by the endotoxin treatment. The effect was associated with an increase in the sensitivity of glutaminase flux to phosphate, an activator of the enzyme. These findings are similar to the activation of glutaminase by glucogenic hormones. We, therefore, propose that the increased hepatic consumption of glutamine during endotoxemia is due to an activation of glutaminase that is only evident in intact mitochondria.

Induction of lytic pathways in T cell clones derived from wild-type or protein tyrosine kinase Fyn mutant mice

The OVA-reactive CD4+ Th1 clones and alloreactive CD8+ clones derived from wild-type or fyn-/- mice serve as model systems which have allowed us to investigate several aspects of the molecular events associated with T cell-mediated cytotoxicity, including 1) the differential utilization of two distinct cytolytic pathways by CD4+ Th1 clones and CD8+ CTL, 2) a comparison of the pathways of lysis induced by stimulation of the TCR or by alternative stimuli, 3) the requirement of Fyn for derivation of antigen-specific T-cell clones having properties of CD4+ Th1 and CD8+ CTL cells 4) the differential requirement of Fyn in the induction of responses by TCR and the alternative stimuli. Stimulation through the TCR, either by APC bearing relevant antigen or by immobilized anti-CD3 mAb, resulted in comparable levels of target cell lysis by clones from both wild-type and fyn-/- mice. These clones also utilize the Fas pathway to lyse target cells. Thus, Fyn does not appear to be required for expression of the Fas pathway when triggered through the TCR. In contrast, lysis of target cells by T-cell clones lacking Fyn was deficient when stimulated through Thy-1 or Ly-6C (using mAb) or with Con A or phorbol ester as compared to clones derived from wild-type mice. The basis for the defect in response to stimulation through the GPI-linked molecules appears to be a signaling defect which affects all of the functional responses we measured, while the defect in response to Con A stimulation appears to affect lysis but not lymphokine production. Thus, Fyn expression is selectively required for efficient activation of the Fas pathway of lysis through Thy-1, Ly-6C, and by Con A or phorbol ester in these T-cell clones. CD8+ clones derived from fyn-/- mutant mice, like clones derived from wild-type mice, display antigen-specific lysis, and appear to express perforin message and perforin protein. A Ca(++)-dependent (presumably perforin/exocytosis) component and Fas component of lysis was detected in CD8+ clones derived from fyn-/- mutant mice. Thus, Fyn is not required for expression of these components of antigen specific lysis by CD8+ alloreactive CTL clones. It appears that CD8+ clones that use multiple lytic mechanisms may selectively employ the perforin or Fas-based pathway depending on properties of the target cell or stimulus.(ABSTRACT TRUNCATED AT 400 WORDS)

Differential requirement for protein tyrosine kinase Fyn in the functional activation of antigen-specific T lymphocyte clones through the TCR or Thy-1

The protein tyrosine kinase Fyn has been shown to be involved in signal transduction through the TCR and the glycosyl-phosphatidylinositol-linked surface molecule Thy-1 expressed on T cells. In this study, we examine the requirement for Fyn expression in signaling through the TCR or Thy-1 using a panel of Ag-specific T cell clones derived from fyn-/- mutant mice. These clones do not express normal Fyn protein, as measured by immune-complex kinase reaction using anti-Fyn Ab. Stimulation through the TCR, either by APC bearing relevant Ag or by immobilized anti-CD3 mAb, resulted in comparable levels of proliferation, lymphokine production, and cytolysis by clones from both wild-type and fyn-/- mice. In contrast, stimulation through Thy-1, using soluble (or cross-linked) anti-Thy-1 mAb, was deficient, as measured by these responses. Thus, Fyn expression is selectively required for functional activation through Thy-1 in these T cell clones.

Differential requirement for protein tyrosine kinase Fyn in the functional activation of antigen-specific T lymphocyte clones through the TCR or Thy-1

The protein tyrosine kinase Fyn has been shown to be involved in signal transduction through the TCR and the glycosyl-phosphatidylinositol-linked surface molecule Thy-1 expressed on T cells. In this study, we examine the requirement for Fyn expression in signaling through the TCR or Thy-1 using a panel of Ag-specific T cell clones derived from fyn-/- mutant mice. These clones do not express normal Fyn protein, as measured by immune-complex kinase reaction using anti-Fyn Ab. Stimulation through the TCR, either by APC bearing relevant Ag or by immobilized anti-CD3 mAb, resulted in comparable levels of proliferation, lymphokine production, and cytolysis by clones from both wild-type and fyn-/- mice. In contrast, stimulation through Thy-1, using soluble (or cross-linked) anti-Thy-1 mAb, was deficient, as measured by these responses. Thus, Fyn expression is selectively required for functional activation through Thy-1 in these T cell clones.

Anergic T-lymphocyte clones have altered inositol phosphate, calcium, and tyrosine kinase signaling pathways

Full activation of TH1 helper T lymphocytes requires ligation of the specific T-cell antigen receptor (TCR) and a second signal provided by costimulator molecule(s) expressed on particular antigen-presenting cells. Stimulation via the TCR complex alone generates a subsequent unresponsive state characterized by an inability to produce interleukin 2. We report here that such anergic cells exhibit multiple alterations in TCR-associated signaling. The basal levels of intracellular free calcium and phosphatidylinositol 1,4,5-trisphosphate are elevated in anergic cells, and the levels fail to increase significantly upon subsequent restimulation. Examination of phospholipase C-gamma 1 reveals evidence for post-translational modification, correlating with increased tyrosine phosphorylation of the molecule. Tyrosine phosphorylation of additional substrates identified from whole-cell lysates also is altered compared to untreated cells, suggesting a modification in net tyrosine kinase activity. Although the level of kinase activity present in TCR/CD3 or Lck immunoprecipitates is modestly altered after induction of anergy, there is a dramatic increase in specific Fyn-associated tyrosine kinase activity in anergic cells and increased phosphorylation of a 110-kDa protein that is coimmunoprecipitated with Fyn. These results are consistent with a model in which anergic TH1 lymphocytes display a fundamental alteration in TCR-mediated tyrosine kinase activity, associated with changes in phospholipase C-gamma 1, inositol phosphates, and intracellular free calcium.

The gamma chain of the high-affinity receptor for IgE is a major functional subunit of the T-cell antigen receptor complex in gamma delta T lymphocytes

T-cell activation is a consequence of the clonotypic T-cell antigen receptor (TCR) binding to an antigen followed by signal transduction via the invariant subunits of the TCR/CD3 complex. gamma delta TCR cells are a small subset of T cells that populate both the epithelial and lymphoid tissues and have unique antigen specificity and function. However, the composition of invariant chains within the gamma delta TCR/CD3 complex has not been well characterized. Here we report that, unlike the majority of alpha beta T cell, gamma delta T cells isolated from spleen and intestinal epithelial tissue express high levels of the gamma chain of the high-affinity receptor for IgE (Fc epsilon RI gamma) as one invariant subunit of their TCR/CD3 complex. Fc epsilon RI gamma exists as both a homodimer and a heterodimer associated with the TCR zeta chain. Moreover, stimulation of the gamma delta TCR results in rapid tyrosine phosphorylation of Fc epsilon RI gamma. Our results suggest that utilization of distinct receptor signaling components may enable the coupling of antigen stimulation to the activation of different signal transduction pathways in alpha beta and gamma delta T cells.

Mutagenicity of the bile of dogs with an experimental model of an anomalous arrangement of the pancreaticobiliary duct

To learn the reasons for the high incidence of biliary carcinoma in patients with anomalous arrangement of the pancreaticobiliary duct (APBD) mutagenicity of the bile of APBD-modeled dogs that had received a dorsal pancreatico-cholecystostomy was assayed by the Ames Salmonella mutation test. The bile from two out of 18 APBD dogs was mutagenic for Salmonella typhimurium strain TA98 under the condition of metabolic activation by rat liver S9 fraction, while the bile from 17 normal dogs was not mutagenic. Furthermore, the bile from five APBD dogs i.p. administered 1-nitropyrene (1-NP), which is a typical environmental mutagen, was more mutagenic for strain TA98 than that from 1-NP-treated normal dogs. The bile from the APBD dogs had very high amylase activity, indicating that the bile contained pancreatic juice as a result of the pancreatico-cholecystostomy. When pancreatic juice from a normal dog was added to the bile from 1-NP-treated normal dogs, mutagenicity of the bile increased 1.6- to 2.0-fold. Furthermore, sulfatase increased the mutagenic activity of the bile in the presence of the pancreatic juice. HPLC revealed that the bile from a 1-NP-treated APBD dog contained mutagenic 1-nitro-6/8-hydroxypyrene and 1-nitro-3-hydroxypyrene, while bile from a 1-NP-treated normal dog did not contain these deconjugated products. The pancreatic juice from a normal dog had very high gamma-glutamyltransferase (GGT) and aminopeptidase activities and low sulfatase activity, but it had no beta-glucuronidase activity. In addition, the bacteria that easily infect the biliary duct of APBD dogs, Escherichia coli, Klebsiella, Enterobacter and Proteus, had high beta-glucuronidase activity. In particular, Klebsiella showed a very high sulfatase activity. These results suggest that pancreatic juice enzymes and bacteria infecting the biliary duct deconjugate the detoxified mutagens in the bile and induce mutagenicity of the bile from APBD dogs or APBD patients.

Multiple components of the T cell antigen receptor complex become tyrosine-phosphorylated upon activation

Triggering of the multicomponent T cell antigen receptor (TCR) complex results in several biochemical processes which are critical for the functional activation of T lymphocytes. One common process is the tyrosine phosphorylation of several proteins, including the TCR zeta chain. Here we show that in addition to TCR zeta, other subunits (CD3 gamma, CD3 delta, and CD3 epsilon) of the TCR complex can also be tyrosine-phosphorylated in response to antigen receptor stimulation. This rapid phosphorylation was detected in several mature murine T cell subsets, including CD4+ type 1 and 2 helper cells (TH1 and TH2). Therefore, tyrosine phosphorylation of multiple TCR components in addition to TCR zeta may be an important event during the initiation of the signaling cascade leading to T cell activation.

A rapid method for detection of flavivirus antigens: staphylococcal co-agglutination test using monoclonal antibodies to Japanese encephalitis virus

Staphylococcus aureus rich in protein A when coated with monoclonal antibodies (MoAb) to Japanese encephalitis virus (JEV) gave a highly specific reaction with flavivirus antigens. The bacteria coated with JEV species-specific MoAb gave a strong co-agglutination with fifty-six JEV isolates from various parts of China, but no co-agglutination with Murray Valley encephalitis (MVE) and Kunjin (Kun) virus antigens. The flavivirus- and subgroup-specific MoAbs were reactive with MVE and Kun, as well as with the majority of the JEV strains. Blocking test with homologous MoAbs abolished co-agglutination further confirming its specificity. Numerous virus particles were observed on the surface of MoAb-coated staphylococci under the electron microscope after co-agglutination. The test appeared rapid, specific, simple to perform, and useful for rapid detection and identification of flaviviruses.