Prediction of bone fracture by bone mineral density in Taiwanese

BACKGROUND AND PURPOSE

This study evaluated whether lumbar spine bone mineral density (BMDL) and the rate of change of BMDL could predict the risk of bone fracture in Taiwanese.

METHODS

In 1989, a baseline survey was carried out in Lin-Kou Township. BMDL was measured using dual photon absorptiometry in 404 healthy volunteers. In 1994/95, a second survey was conducted to reexamine the BMDL and fracture history as well as the risk factors associated with fracture in these subjects. Fractures were classified according to the causes of the injury as severe or mild trauma.

RESULTS

Of the 404 original examinees, 381 (79%) participated in the second survey. Twenty-six subjects had experienced a total of 32 fracture incidents during their lifetime and 10 subjects had experienced fracture during the observation period. After adjusting for the effect of body mass index, gender, and age, each standard deviation of decrease in BMDL was found to be associated with a significant 2.38-fold increase in the risk of mild trauma fracture, and a BMDL below the fracture threshold was associated with a 3.93-fold increase of fracture risk. Higher BMDL change rates were found in subjects with a history of fracture.

CONCLUSION

This study indicates the importance of maintaining the BMDL above the fracture threshold (1 g/cm2). The strategy for fracture prevention should be directed at prevention of age-related bone loss.

The solution structure of [d(CGC)r(amamam)d(TTTGCG)]2

The solution structure and hydration of a DNA.RNA hybrid chimeric duplex [d(CGC)r(amamam)d(TTTGCG)]2 in which the RNA adenines were substituted by 2'-O-methylated riboadenines was determined using two-dimensional NMR, simulated annealing, and restrained molecular dynamics. Only DNA residue 7T in the 2'-OMe-RNA.DNA junction adopted an O4'-endo sugar conformation, while the other DNA residues including 3C in the DNA.2'-OMe-RNA junction, adopted C1'-exo or C2'-endo conformations. The observed NOE intensity of 2'-O-methyl group to H1' proton of 4am at the DNA.2'-OMe-RNA junction is much weaker than those of 5am and 6am. The 2'-O-methyl group of 4am was found to orient towards the minor groove in the trans domain while the 2'-O-methyl groups of 5am and 6am were found to be in the gauche (+) domain. In contrast to the long-lived water molecules found close to the RNA adenine H2 and H1' protons and the methyl group of 7T in the RNA-DNA junction of [d(CGC)r(aaa)d(TTTGCG)]2, there were no long-lived water molecules found in [d(CGC)r(amamam)d(TTTGCG)]2. This is probably due to the hydrophobic enviroment created by the 2'-O-methylated riboadenines in the minor groove or due to the wider minor groove width in the middle of the structure. In addition, the 2'-O-methylation of riboadenines in pure chimeric duplex increses its melting temperature from 48.5 degrees C to 51.9 degrees C. The characteristic structural features and hydration patterns of this chimeric duplex provide a molecular basis for further therapeutic applications of DNA.RNA hybrid and chimeric duplexes with 2'-modified RNA residues.

Association of aflatoxin B(1)-albumin adduct levels with hepatitis B surface antigen status among adolescents in Taiwan

Chronic hepatitis B virus (HBV) infection and aflatoxin B(1) (AFB(1)) exposure interact synergetically to induce hepatocellular carcinoma. One suggested mechanism for this interaction is the enhanced activation of AFB(1) in chronically HBV-infected individuals. Whereas no associations between chronic HBV infection and AFB(1)-albumin adducts were observed in several studies in adults, hepatitis B surface antigen (HbsAg)-positive children were found to have elevated adducts in Gambia. To assess the association between chronic HBV infection and AFB(1)-albumin adduct level in Taiwan, 200 junior high school adolescents from 20 townships were assayed for HBsAg and AFB(1)-albumin adducts. The mean AFB(1)-albumin adduct level was higher in HBsAg-positive compared with HBsAg-negative subjects. The association between HBsAg status and AFB(1)-albumin adducts remained after multivariate adjustment. This finding additionally supports the synergetic interaction between HBV and AFB(1), but the mechanism remains to be elucidated.

Changing prevalence of hepatitis C virus genotypes: molecular epidemiology and clinical implications in the hepatitis C virus hyperendemic areas and a tertiary referral center in Taiwan

To determine the hepatitis C virus (HCV) genotype distribution in Taiwan and to clarify the relationship between genotype and the pathogenesis of HCV infection, 1,164 subjects positive for serum HCV antibodies and HCV RNA from three HCV hyperendemic areas (Masago, Tzukuan, and Taoyuan) and a tertiary referral center in Taiwan were studied during 1995-1997. HCV genotypes and viral loads were determined using Okamoto's method and branched DNA assay, respectively. Genotype 1b was the most prevalent in Tzukuan (61.9%), Taoyuan (76.9%), and the referral center (47.0%). By contrast, genotype 2a was the major HCV type in Masago (63.5%). Prevalence of genotype 1b positively and that of genotype 2a negatively correlated to age, regardless of study populations (P < 0.01). Based on multivariate analysis, the significant factors associated with the presence of cirrhosis, with or without hepatocellular carcinoma, in chronic hepatitis C patients were genotype 1b and age. In conclusion, these results underline that independent HCV outbreaks continue in HCV hyperendemic areas in Taiwan, concomitant with a changing relative prevalence of HCV genotypes in relation to age. Both the correlation of genotype 1b with age (cohort effect) and intrinsic properties of HCV genotypes are probably responsible for the association between genotype and the pathogenesis of HCV infection.

Cost-effectiveness of a school-based tobacco-use prevention program

OBJECTIVE

To determine the cost-effectiveness of a school-based tobacco-use prevention program.

DESIGN

Using data from the previously reported 2-year efficacy study of the Project Toward No Tobacco Use (TNT), we conducted a decision analysis to determine the cost-effectiveness of TNT. The benefits measured were life years (LYs) saved, quality-adjusted life years (QALYs) saved, and medical care costs saved, discounted at 3%. The costs measured were program costs. We quantified TNT's cost-effectiveness as cost per LY saved and cost per QALY saved.

INTERVENTION

A 10-lesson curriculum designed to counteract social influences and misconceptions that lead to tobacco use was delivered by trained health educators to a cohort of 1234 seventh-grade students in 8 junior high schools. A 2-lesson booster session was delivered to the eighth-grade students in the second year. The efficacy evaluation was based on 770 ninth-grade students who participated in the program in the seventh and eighth grades and in both the baseline and the 2-year follow-up survey.

RESULTS

Under base case assumptions, at an intervention cost of $16 403, TNT prevented an estimated 34.9 students from becoming established smokers. As a result, we could expect a saving of $13 316 per LY saved and a saving of $8482 per QALY saved. Results showed TNT to be cost saving over a reasonable range of model parameter estimates.

CONCLUSIONS

The TNT is highly cost-effective compared with other widely accepted prevention interventions. School-based prevention programs of this type warrant careful consideration by policy makers and program planners.

All-trans-retinoic acid increased the expression of integrin alpha5beta1 and induced "anoikis" in SMMC-7721 hepatocarcinoma cell

It is extensively shown that integrin can regulate various cellular functions, including apoptosis, probably by contributing to signal transduction processes through interaction with extracellular matrix (ECM) proteins. In the present study, DNA flow cytometric analysis demonstrated that SMMC-7721 hepatocarcinoma cells treated with 80 microM all-trans-retinoic acid (atRA) showed an increased expression of the integrin alpha5beta1, which was associated with the growth inhibition of the cells. We found that atRA treated cells showed obvious apoptosis. Then, it was postulated that the enhanced content of integrin alpha5beta1 in the absence of ligation with fibronectin (Fn) would stop transducing survival signals, and lead to decreased cell growth and apoptosis. To elucidate this hypothesis, we cultured the atRA treated cell in L-poly-lysine-coated and Fn-coated flask, respectively. The results indicated that Fn binding prevented the cells from apoptosis induced by atRA, in contrast to L-poly-lysine binding. When the transfectant with enhanced expression of integrin alpha5beta1 at the same level of atRA treated cell was cultured in L-poly-lysine-coated flask, apoptosis was triggered. However, apoptotic cell was not detected when those cells were cultured in Fn-coated flask. Meanwhile, culturing the transfectant in the antibody (against integrin alpha5 subunit)-coated flask induced 18.33% of the cells into apoptosis, which is far more than the control group. Our study suggests that increased expression of integrin alpha5beta1 on the surface of SMMC 7721 hepatocarcinoma cell treated by atRA, when unbound to Fn, would stop transducing survival signals to lead to "anoikis", and can be reverted by the interaction of integrin alpha5beta1 with Fn.

Effect of interleukin (IL)-12 and IL-15 on apoptosis and proliferation of umbilical cord blood mononuclear cells

Decreased graft-versus-host disease (GVHD) in cord blood (CB) transplantation may be attributed to the immunological immaturity and susceptibility to apoptosis of CB mononuclear cells (MNCs). Cytokines like interleukin (IL)-12 and IL-15 may be used for in vivoadministration or ex vivo expansion of lymphoid cells for more rapid recovery following stem cell transplant, and for providing a graft-versus-leukemia (GVL) effect. We investigated the effects of IL-12 and IL-15, alone or in combination on apoptosis and proliferation of both CB and adult peripheral blood (APB) MNCs, with particular emphasis on CB CD4+, CD8+ and CD56+ lymphocyte subpopulations. The results of our study indicated that: (1) the combination of IL-12+IL-15 resulted in a greater degree of CB and APB apoptosis than either cytokine alone; (2) the level of both spontaneous and cytokine-induced apoptosis by IL-12 and/or IL-15 are greater in CB MNCs than in APB MNCs using TUNEL assays; (3) IL-15 is superior to IL-12 in enhancing the proliferative response in CB and APB MNCs; (4) the combination of IL-12+IL-15, but not either cytokine alone, significantly enhanced apoptosis in CD8+ and CD56+ CB subsets, but not in CD4+ CB subsets; (5) IL-12 or IL-15 alone resulted in increased proliferation in CD4+, CD8+ and CD56+ CB subsets, with IL-12+IL-15 producing the greatest increase of proliferation in all three CB subsets; and (6) IL-15 and/or IL-12 significantly upregulate Fas (CD95) expression on CB T and NK cells. These findings may have therapeutic implications when designing cytokine therapy in patients receiving CB transplant.

[GnT-V overexpression in human hepatocarcinoma cells affects its migration and expression of cell adhesion molecules]

The purpose of this paper is to study the effect of N-acetylglucosaminyltransferase V (GnT-V) overexpression on the migration of 7721 cells and its mechanism. The abilities of migration of both 7721 cells transfected with GnT-V cDNA and 7721 cells transfected with pcDNA3 was detected, the expressions of integrin and E-cadherin which are important adhesion molecules on surface membrane and closely related to the abilities of invasion and metastasis. Cell migration abilities were measured by the agarose drop explant method. Flow cytometric analysis (FACS) was applied to determine the relative amounts of integrin alpha 5 and beta 1 subunits on the cell surface while RTPCR was carried out to determine the expression of their mRNA. The expression of E-cadherin was examined by the immunocytochemical ABC method. Western blot analysis was carried out to examine the expression of beta-catenin. GnT-V overexpression enhanced evidently the migration ability of 7721 cells and increased the amount of integrin alpha 5 subunit to 2.9 times of that of control while the amount of beta 1 subunits was not significantly changed. Besides, the expressions of E-cadherin and beta-catenin were enhanced at different levels in GnT-V/7721 cells compared with mocked. The results suggested that the overexpression of GnT-V related to the production of N-linked sugar chains could promote the expressions of integrin, E-cadherin and beta-catenin on 7721 cells so that the migration ability of tumor cells was enhanced.

Variability in aflatoxin-albumin adduct levels and effects of hepatitis B and C virus infection and glutathione S-transferase M1 and T1 genotype

Exposure to aflatoxin B1 (AFB1), an important cofactor in the etiology of hepatocellular carcinoma in Taiwan, is influenced by dietary and other factors. The present study examined the intraindividual variability in AFB1-albumin adducts, the most reliable long-term biomarker of AFB1 exposure, and whether the baseline or follow-up adduct levels and the intraindividual variability in adduct levels are modified by endogenous and environmental factors. The study measured AFB1-albumin adduct levels among 264 healthy male residents of three townships (Hu-Hsi, Ma-Kung, and Pai-Hsa) of Penghu Islets, Taiwan, at two different time points with a median interval of 1.68 years (range 1.00-3.17 years). There was a generalized reduction in the adduct levels, with the median values being 22.1 pmol/mg (range 5.0-355.8 pmol/mg) at time 1 and 14.3 pmol/mg (range 5.0-205.2 pmol/mg) at time 2. This intraindividual variability in adduct levels was inversely associated with the age of subjects and the time interval between the two blood draws. The variability in adduct levels was lower among subjects in Hu-Hsi and Pai-Hsa townships as compared to those in Ma-Kung. No significant association was observed for the intraindividual variability in AFB1-albumin adducts with regard to the season when blood was drawn. There was also no significant association between intraindividual variability and hepatitis B surface antigen, anti-hepatitis C virus (anti-HCV), glutathione S-transferase (GST) M1, or GSTT1 status. In conclusion, we found substantial intraindividual variability in the AFB1 exposure (as determined by AFB1-albumin adducts) in Taiwan, which was probably more likely related to dietary or other environmental influences rather than to endogenous factors (e.g., hepatitis B/C viral infection or GST M1/T1 genetic status).

Ultrasonic characteristics of periportal collateral circulation in hepatocellular carcinoma with portal vein invasion

Real-time ultrasound (US) was used to analyze the morphological characteristics of periportal collateral circulation (PPCC) and the hepatic artery in hepatocellular carcinoma (HCC) patients with portal vein invasion (PVI). During a 5-year interval, a total of 17 HCC patients with main portal vein thrombosis and detectable periportal vessels were collected: 14 men and 3 women, aged 27 to 76 years old. We examined these patients' periportal vessels by real-time US, then differentiated PPCC from hepatic artery by duplex Doppler US. We analyzed the morphological appearances of real-time US imaging of PPCC and the hepatic artery. Our results showed that the PPCC was always torturously worm-like in appearance on real-time US, and the hepatic artery usually had a linear channel appearance on real-time US. When these two kinds of vessels were seen simultaneously along the pathway of a thrombosed portal vein, the inner vessel was always the hepatic artery with linear channel structure, and the outer vessel was always PPCC with a torturously worm-like structure. In conclusion, real-time US is a useful and reliable modality in detecting periportal vessels and differentiating PPCC from the hepatic artery.

Genetic polymorphisms of glutathione S-transferases M1 and T1 associated with susceptibility to aflatoxin-related hepatocarcinogenesis among chronic hepatitis B carriers: a nested case-control study in Taiwan

This study was conducted to investigate the modifying effect of glutathione S-transferase (GST) M1 and T1 polymorphisms on aflatoxin-induced hepatocarcinogenesis among chronic hepatitis B virus surface antigen (HBsAg) carriers. A total of 79 HBsAg-positive cases of hepatocellular carcinoma (HCC) diagnosed between 1991 and 1997 were identified and individually matched to one or two HBsAg-positive controls on age, gender, residence and date of recruitment from the same cancer screening cohort in Taiwan. Blood samples were tested for hepatitis B and C viral markers by enzyme immunoassay and for aflatoxin B(1) (AFB(1))-albumin adducts by competitive enzyme-linked immunosorbent assay. GSTM1 and GSTT1 genotypes were determined by PCR. There was a statistically significant relationship between detectable levels of AFB(1)-albumin adducts in serum and risk of HCC among chronic HBsAg carriers, with an adjusted odds ratio (OR) of 2.0 [95% confidence interval (CI) 1.1-3.7]. In addition, the effect of aflatoxin exposure on HCC risk was more pronounced among chronic HBsAg carriers with the GSTT1 null genotype (OR 3.7, 95% CI 1.5-9.3) than those who were non-null (OR 0.9, 95% CI 0.3-2.4). The interaction between serum AFB(1)-albumin adduct level and GSTT1 genotype was statistically significant (P = 0.03). For GSTM1 the effect of aflatoxin exposure on HCC risk in those with the null genotype was also greater (adjusted OR 2.8, 95% CI 1.0-7.8) than in those with the gene present (adjusted OR 1.8, 95% CI 0.8-4.5), but the difference was not significant (P = 0.91). Notably, when the interaction between aflatoxin exposure and GSTT1 genotype was considered, aflatoxin exposure by itself was not a significant determinant of HCC risk among chronic HBsAg carriers. These results demonstrate the importance of gene-environment interactions in the multifactorial development of HCC.

Influence of hepatitis C virus on the profiles of patients with chronic hepatitis B virus infection

BACKGROUND

Hepatitis B virus (HBV) and hepatitis C virus (HCV) are the most common causes of chronic liver disease, cirrhosis and hepatocellular carcinoma. The influence of HCV infection on the clinicopathological and virological profiles of chronic HBV infection was investigated.

METHODS

A total of 100 chronic HBV carriers with histopathological diagnoses by liver biopsy were studied. Hepatitis B e antigen (HBeAg) and anti-HCV antibody were tested. Serum HCV-RNA was detected by using a nested reverse transcription-PCR assay. A branched DNA (bDNA) assay was used to detect HBV-DNA and quantitate the serum levels.

RESULTS

Eighteen (18%) of 100 patients were positive for anti-HCV and HCV-RNA. Patients with concurrent HCV and HBV infection were significantly older than those without HCV infection (P < 0.05). The positive rates of HBeAg and HBV-DNA as well as the serum levels of HBV-DNA in patients with concurrent HCV and HBV infection were significantly lower than those without concurrent HCV and HBV infection (P < 0.01, P < 0.05, and P < 0.001, respectively). By using multivariate analysis, the factors of seroconversion of HBeAg and decreasing level of HBV-DNA were significantly correlated to concurrent HCV and HBV infection in chronic HBV carriers. The factors of increasing age and concurrent HCV and HBV infection were significantly correlated to seroconversion of HBeAg.

CONCLUSIONS

The concurrent HCV and HBV infection in chronic HBV carriers might result in a suppression of HBV replication that presented with a lower level of serum HBV-DNA and HBeAg seroconversion. Nevertheless, neither more obvious increase in biochemical parameters nor histopathological progression to more advanced liver diseases was observed.

Sex differences in relation to serum hepatitis B e antigen and alanine aminotransferase levels among asymptomatic hepatitis B surface antigen carriers

This study aimed to investigate sex differences in relation to hepatitis B e antigen (HBeAg) and serum alanine aminotransferase (ALT) levels in chronic asymptomatic hepatitis B virus (HBV) infection. HBeAg and ALT level were determined in 636 asymptomatic hepatitis B surface antigen carriers. There was no significant sex differences in the age-adjusted prevalence of HBeAg. Abnormal ALT level (>45 IU/l) was more frequent in carriers with HBeAg (17.5% vs 7.6%; P = 0.001). Multivariate analysis indicated that male sex (odds ratio, 2.0; 95% confidence interval, 1.1-3.6) and HBeAg (odds ratio, 2.6; 95% confidence interval, 1.6-4.3) were independent risk factors for abnormal ALT levels. Male sex and HBeAg-positivity are independent risk factors for abnormal ALT activity in chronic HBV infection. This observation may be related to sex differences in chronic HBV infection.

An improved and easy method for the preparation of 2,2-disubstituted 1-nitroalkenes

Reactions of ketones 1, nitromethane 2, and catalytic amount of piperidine 3 in the presence of mercaptan 6 generate beta-nitroalkyl sulfides 7-9. At 0 degrees C and by the use of dichloromethane as solvent, beta-nitroalkyl sulfides 7-9 can be oxidized by m-chloroperoxybenzoic acid (m-CPBA) 10 to generate beta-nitroalkyl sulfoxides 11-13 and undergo elimination in carbon tetrachloride solution to produce medium to high yield of 2,2-disubstituted 1-nitroalkenes 5. The irreversibility of the synthetic mechanism not only can overcome the reversibility of the Henry reaction in the synthesis of 2,2-disubstituted 1-nitroalkenes 5 but also can generate the major products "exo-nitro olefins"5c-e when cyclic ketones 1c-e were used. Under similar conditions, medium to high yield of 5-substituted-2-nitromethyl-2-phenylthioadamantane 17 also can be prepared from the reaction of 5-substituted-2-adamantanones 15, nitromethane 2, piperidine 3, thiophenol 6a. The intermediate17 can be oxidized by m-CPBA 10 in dichloromethane solution and then undergo elimination at room temperature or can be dissolved in solvent, coated on silica gel, and then heated at 90-100 degrees C to generate 5-substituted-2-nitromethyleneadamantane 16.

Betel quid chewing as a risk factor for hepatocellular carcinoma: a case-control study

The role of betel quid chewing in the aetiology of hepatocellular carcinoma (HCC) was evaluated in a case-control study including 263 pairs of age- and sex-matched HCC patients and healthy controls. Serum hepatitis B surface antigen (HBsAg), and antibodies to hepatitis C virus (anti-HCV) were determined, and standardized personal interview conducted using a structured questionnaire. Multivariate analysis indicated that betel quid chewing (odds ratio (OR), 3.49; 95% confidence interval (CI), 1.74-6.96), HBsAg (OR, 16.69; 95% CI, 9.92-28.07), anti-HCV (OR, 38.57; 95% CI, 18.15-81.96), and educational duration of less than 10 years (OR, 1.71; 95% CI, 1.05-2.78) are independent risk factors of HCC. In addition, there was an additive interaction between betel quid chewing and chronic infection with either hepatitis B virus (synergy index, 5.37) or hepatitis C virus (synergy index, 1.66). Moreover, risk on HCC increased as duration of betel quid chewing increased, or amount of betel quid consumed (each P for trend < 0.0001).

Hepatoprotective effects of Arctium lappa on carbon tetrachloride- and acetaminophen-induced liver damage

The root of Arctium lappa Linne (A. lappa) (Compositae), a perennial herb, has been cultivated for a long time as a popular vegetable. In order to investigate the hepatoprotective effects of A. lappa, male ICR mice were injected with carbon tetrachloride (CCl4, 32 microl/kg, i.p.) or acetaminophen (600 mg/kg, i.p.). A. lappa suppressed the SGOT and SGPT elevations induced by CCl4 or acetaminophen in a dose-dependent manner and alleviated the severity of liver damage based on histopathological observations. In an attempt to elucidate the possible mechanism(s) of this hepatoprotective effect, glutathione (GSH), cytochrome P-450 (P-450) and malondialdehyde (MDA) contents were studied. A. lappa reversed the decrease in GSH and P-450 induced by CCl4 and acetaminophen. It was also found that A. lappa decreased the malondialdehyde (MDA) content in CCl4 or acetaminophen-intoxicated mice. From these results, it was suggested that A. lappa could protect the liver cells from CCl4 or acetaminophen-induced liver damages, perhaps by its antioxidative effect on hepatocytes, hence eliminating the deleterious effects of toxic metabolites from CCl4 or acetaminophen.

The molecular epidemiology and clinical significance of TT virus (TTV) infection in healthy blood donors from southern Taiwan

To evaluate the molecular epidemiology and clinical significance of th

Efficacy trial of Vi polysaccharide vaccine against typhoid fever in south-western China

OBJECTIVE

To test the efficacy of locally produced Vi vaccine over a time period of longer than one year.

METHODS

A double-blinded, randomized field trial was performed in Guangxi Zhuang Autonomous Region in south-western China, using 30 micrograms doses of locally produced Vi. Enrolled subjects were 3-50 years of age, although the majority (92%) were school-aged children, who have the highest rate of typhoid fever in this setting. A total of 131,271 people were systematically allocated a single dose of 30 micrograms of Vi polysaccharide or saline placebo. The study population was followed for 19 months, with passive surveillance conducted in the Ministry of Health and the Regional Health and Anti-epidemic Centre (HAEC). Clinically suspected cases of typhoid fever were confirmed by blood culture, or by serological reaction with O-antigen (Widal tests).

FINDINGS

After 19 months, there were 23 culture-confirmed cases of typhoid fever in the placebo group versus 7 cases in the Vi group (Protective efficacy (PE) = 69%; 95% CI = 28%, 87%). Most of the isolates were from school-aged children: 22 cases in the placebo group versus 6 in the Vi group (PE = 72%; 95% CI = 32%, 82%). No serious post-injection reactions were observed. The locally produced Vi polysaccharide vaccine showed levels of protective efficacy similar to those for Vi vaccine produced in industrial countries.

CONCLUSION

The slightly higher dose of vaccine did not seem to alter efficacy significantly in China.

The serological and molecular epidemiology of GB virus C/hepatitis G virus infection in a hepatitis C and B endemic area

OBJECTIVES

To investigate the serological and molecular characteristics of GB virus C/hepatitis G virus (GBV-C/HGV) infection in the hepatitis C virus (HCV)/hepatitis B virus (HBV)-endemic areas in Taiwan.

METHODS

Sera from 200 residents from Masago, an HCV/HBV-endemic community in Taiwan, and 400 blood donors were tested for GBV-C/HGV RNA by using nested reverse transcription-polymerase chain reaction and for antibodies to GBV-C/HGV E2-protein (anti-E2) by an enzyme-linked immunosorbent assay. Phylogenetic analysis of GBV-C/HGV was performed.

RESULTS

The prevalence of GBV-C/HGV viraemia, anti-E2 and GBV-C/HGV exposure among residents of Masago was significantly higher than that among donors (17.0%, 25.5% and 39.5% vs. 3.3%, 7.5% and 10.3%, respectively; all P < 0.0001). In Masago, the prevalence of GBV-C/HGV exposure was significantly higher in residents exposed to HCV than in those without HCV exposure (45.8% vs. 24.1%;P< 0.005). Based on multivariate analyses, HCV viraemia was the only significant factor associated with elevated levels of alanine aminotransferase in Masago. Phylogenetic analysis showed all 34 GBV-C/HGV isolates from Masago clustered within genotype 3.

CONCLUSIONS

GBV-C/HGV was highly prevalent in Masago, an HCV/HBV-endemic community in Taiwan. HCV viraemia played the most important clinical hepatopathic role in the area. Infections with other hepatitis viruses did not influence the anti-E2 seroconversion from GBV-C/HGV infections.

Identification and characterization of a novel gene that is upregulated in leukaemia cells by nitric oxide

Nitric oxide (NO) inhibits growth and induces differentiation in acute myeloid leukaemia (AML) cells. To identify genes associated with these processes, we studied the effect of NO on AML gene expression using the technique of Representational Difference Analysis. Exposure of HL-60 cells to the NO donor DETA-NO for 24 h induced the expression of a novel gene that was named rno (regulated by nitric oxide). Treatment of HL-60 cells with dimethyl sulphoxide induced expression of rno, but treatment with Vitamin D3 or all-trans retinoic acid did not. Upregulation of rno by NO was cGMP independent. Northern blot analysis indicated that constitutive expression of the novel gene was limited to leucocytes. Three isoforms of rno were identified. An rno cDNA clone was obtained by screening a human leucocyte library. The nucleotide sequence of the open reading frame shared significant homology with that of the human ribonuclease/angiogenin inhibitor (RI). The predicted amino acid sequence indicated that, like RI, rno is leucine and cysteine rich and is comprised of a series of repetitive elements (leucine-rich repeats) that may mediate macromolecular interactions. Enhancement of expression of rno may be a component of the process by which differentiation and growth inhibition of leukaemia cells is induced by NO.

The dynamic range for gain control of NMDA receptor-mediated synaptic transmission at a single synapse

Although the level at which NMDA receptors (NMDARs) are activated can profoundly influence the direction and extent of long-term changes in synaptic strength, the probabilistic nature of quantal release at individual synapses makes it difficult to determine the dynamic operating range of NMDAR-mediated synaptic transmission. By continually driving glutamate release from a single high-fidelity auditory synapse with bursts of high-frequency stimuli, I show here that NMDAR-mediated EPSCs exhibited incremental summation in their amplitude and did not reach a plateau until six or seven consecutive stimuli into the train. An increase in the initial quantal output, by broadening presynaptic spikes with the potassium channel blocker tetraethylammonium (TEA, 0.2 mm), slightly increased the plateau amplitude at 200/300 Hz but shifted its peak temporally toward the earlier stimuli. These results suggest that the plateau amplitude in TEA reflects the activation of the entire population of synaptic NMDARs and hence the maximal gain of NMDAR-mediated synaptic transmission. This maximum was estimated to be 3.2-fold of the basal synaptic strength, giving a 31% occupancy of synaptic NMDARs by glutamate. Thus, synaptic NMDARs possess a broad dynamic range within which the activity-dependent control of synaptic strength and plasticity can potentially be tuned by the amount of Ca(2+) influx associated with different levels of NMDAR occupancy within the same synapse.

Incidence and associated factors of neutralizing anti-interferon antibodies among chronic hepatitis C patients treated with interferon in Taiwan

BACKGROUND

The administration of interferon (IFN) could be complicated by the development of neutralizing anti-interferon antibodies (NA). This study evaluates the frequency and associated factors of NA among chronic hepatitis C patients treated with different IFNs.

METHODS

Ninety-five chronic hepatitis C patients were randomized to be treated with recombinant IFN-alpha2a (n = 28), IFN-alpha2b (n = 39) or lymphoblastoid IFN-alpha1 (n = 28) given intramuscularly, 3-6 million units, thrice weekly for 24 weeks. Serum samples collected before, during and after the cessation of treatment were checked for NA.

RESULTS

Three patients were withdrawn from treatment. All patients were negative for NA before treatment and 13 (14%) patients developed neutralizing antibodies. Of the 26 patients treated with IFN-alpha2a, 6 (23.1%) developed NA. whereas NA were detected in only 6 (15.4%) of 39 and 1 (3.7%) of 27 patients treated with IFN-alpha2b and IFN-alphanl, respectively. Age, gender, HCV genotype, ALT level, IFN total dose and liver histology were not associated with the development of NA. By using multivariate logistic regression it was shown that pretreatment HCV RNA level and IFN preparation were the two major factors related to the production of NA. The response of treatment was related to pretreatment viremia but not to the presence of NA.

CONCLUSIONS

The frequency of development of NA among Taiwanese patients with chronic hepatitis C might be related to different IFN preparations and pretreatment HCV RNA level. The response of treatment was related to pretreatment HCV RNA level but not to the presence of NA.

Status and natural course of GB virus C/hepatitis G virus infection among high-risk groups and volunteer blood donors in Taiwan

BACKGROUND

Hemophilia, thalassemia and uremia patients are at risk of parenterally transmitted infectious agents. The status and nature of the course of GB virus C/hepatitis G virus (GBV-C/HGV) infection among these groups and blood donors in Taiwan was investigated.

METHODS

Serum GBV-C HGV-RNA and antibodies to GBV-C/HGV envelope-2-protein (anti-E2) were determined in 500 blood donors and in 44 hemophilia, 37 thalassemia and 85 uremia patients. Phylogenetic analysis was performed.

RESULTS

The prevalence of GBV-C/HGV-RNA and anti-E2, respectively, was 38.6 and 27.3% in hemophilia patients, 27.0 and 27.3% in thalassemia patients, 14.1 and 10.6% in uremia patients and 3.4 and 7.2% in blood donors. The prevalence of GBV-C HGV exposure was 59.1 and 51.4% in hemophilia and thalassemia patients, respectively, which was significantly higher than that for uremia patients (22.4%; P < 0.01) and blood donors (10.2%; P < 0.001). The anti-E2 seroconversion rate was 66.7% in blood donors and 47.4, 36.8 and 34.6% in thalassemia, uremia (P < 0.05 compared with blood donors) and hemophilia (P < 0.01 compared with blood donors) patients, respectively. Discrepancies in the prevalence of GBV-C HGV and hepatitis C virus infection were found among the three risk groups. Phylogenetic analysis showed that 51 of 56 GBV-C HGV isolates clustered in group 3; the remaining five were of group 2a. Twelve of 39 viremic patients in the risk groups cleared the virus during the 4 year follow-up period; seven developed concomitant anti-E2 reactivity.

CONCLUSIONS

GB virus C hepatitis G virus infection is epidemic among risk groups and GBV-C HGV group 3 is the major strain in Taiwan. In the risk groups, approximately 18% of infections resolve with concomitant anti-E2 seroconversion within 4 years.

The epidemiology of TT virus (TTV) infection in a hepatitis C and B virus hyperendemic area of southern Taiwan

TT virus (TTV) is a newly isolated DNA virus from the serum of a patient with posttransfusion hepatitis of unknown etiology in 1997. To evaluate the clinical and molecular characteristics of TT virus (TTV) in a hepatitis C virus (HCV) and B (HBV) hyperendemic area (Masago), 200 residents were enrolled in the study. The sera were tested for alanine aminotransferase (ALT), HCV RNA and GB virus C/Hepatitis G virus (HGV) RNA, TTV DNA, HBsAg, anti-HCV and antibodies to HGV E2-protein (anti-E2). TTV DNA was positive in 99 of the 200 sera with a prevalence rate of 49.5%. The prevalence of HBsAg, anti-HCV, HCV RNA, HGV RNA, anti-E2 and HGV exposure (defined as positive for serum HGV RNA and/or anti-E2) was 38.9%, 69.5%, 64.5%, 17.0%, 25.5% and 39.5%, respectively. Neither clinical nor virological factors were associated with TTV viremia. The rate of ALT abnormality was significantly elevated in HCV RNA-positive (34.9%) than -negative (7.0%) residents (p < 0.001). HCV viremia was the only factor significantly associated with ALT elevation by multiple logistic regression (odds ratio: 6.96; 95% C.I.: 2.60-18.7). We concluded that in this HCV/HBV hyperendemic area, the prevalence of TTV DNA was high. No significant clinical factor was observed to be associated with TTV infection. TTV infection is not related to abnormal ALT levels and ALT abnormality was mainly attributable to HCV but not TTV, HBV or HGV infection.

Economic evaluation of Safer Choices: a school-based human immunodeficiency virus, other sexually transmitted diseases, and pregnancy prevention program

OBJECTIVE

To evaluate the cost-effectiveness and cost benefit of Safer Choices, a school-based human immunodeficiency virus, other sexually transmitted diseases, and unintended pregnancy prevention intervention for high school students.

METHODS

The baseline cost-effectiveness and cost benefit were derived in 4 steps: (1) estimation of intervention costs; (2) adaptation of the Bernoulli model to translate increases in condom use into cases of human immunodeficiency virus and other sexually transmitted diseases averted, and development of a model to translate increases in contraceptive use into cases of pregnancy averted; (3) translation of cases averted into medical costs and social costs averted; and (4) calculation of the net benefit of the program. Multivariable sensitivity analysis was performed to determine the robustness of the base-case results.

RESULTS

Under base-case assumptions, at an intervention cost of $105,243, Safer Choices achieved a 15% increase in condom use and an 11% increase in contraceptive use within 1 year among 345 sexually active students. An estimated 0.12 cases of human immunodeficiency virus, 24.37 cases of chlamydia, 2.77 cases of gonorrhea, 5.86 cases of pelvic inflammatory disease, and 18.5 pregnancies were prevented. For every dollar invested in the program, $2.65 in total medical and social costs were saved. Results of most of the scenarios remained cost saving under a wide range of model variable estimates.

CONCLUSIONS

The Safer Choices program is cost-effective and cost saving in most scenarios considered. School-based prevention programs of this type warrant careful consideration by policy makers and program planners. Program cost data should be routinely collected in evaluations of adolescent prevention programs.

[Determination of the active components in Chinese herb Aloe vera L. var. chinensis (Haw.) Berger by capillary zone electrophoresis]

It has been proved that the Chinese herb Aloe vera L. var. chinensis (Haw.) Berger as well as its active components showed many important pharmacology activities. In order to find an easy and low-cost method to control the quality of the herb, a CZE method for the determination of the active components aloin and aloe-emodin in Aloe vera L. var. chinensis (Haw.) Berger was developed in this work. Under the buffer conditions of 24 mmol/L phosphate (pH 10.52), applied voltage of 15 kV and detector wavelength of 254 nm, baseline separation of the active compounds in Aloe vera L. var. chinensis (Haw.) Berger was achieved and the active components were quantitatively analyzed. The linear calibration equations of the two components are: Y= -0.140 + 57.2X (r = 0.997) for aloin and Y = -0.393 + 1.08 x 10(2) X (r = 0.999) for aloe-emodin respectively. In addition, the effects of buffer pH value and organic modifier on the migration behavior of the solutes were also investigated.

Transcription factor NF-kappaB signals antianoikic function of trefoil factor 3 on intestinal epithelial cells

Transcription factor NF-kappaB has both pro-apoptotic and anti-apoptotic properties depending on the cell type. Its role in the intestinal epithelial cell has not been well elucidated. Trefoil factor 3 (TFF3) is an anti-apoptotic peptide secreted by intestinal goblet cells. Here we show that TFF3 activated NF-kappaB p50/p65 heterodimer within 1 h in IEC-18 cells (a nontransformed rat intestinal epithelial cell line). Moreover, we found that TFF3-treated IEC-18 cells are resistant to anoikis, an anchorage-related apoptosis in epithelium. In addition, the stable expression of a mutant form of the endogenous NF-kappaB inhibitor (IkappaBalpha(mut)) in IEC-18 cells results in a significant attenuation of anti-anoikic effect of TFF3. Taken together, these data indicate that (1) TFF3 is an endogenous gastrointestinal peptide with anti-anoikic property; (2) TFF3 activates NF-kappaB in enterocytes; and (3) TFF3-induced resistance to anoikis in intestinal epithelial cells is mediated by a distinct signaling cascade linked to NF-kappaB. Furthermore, our study implicates NF-kappaB as an important regulator in survival pathway of intestinal epithelial cells.

TGF-beta 1 modulated the expression of alpha 5 beta 1 integrin and integrin-mediated signaling in human hepatocarcinoma cells

Integrins are a family of cell surface adhesion molecules which mediate cell adhesion and initiate signaling pathways that regulate cell spreading, migration, differentiation, and proliferation. TGF-beta is a multifunctional factor that induces a wide variety of cellular processes. In this study, we show that, TGF-beta 1 treatment enhanced the amount of alpha 5 beta 1 integrin on cell surface, the mRNA level of alpha 5 subunit, and subsequently stimulated cell adhesion onto a fibronectin (Fn) and laminin (Ln) matrix in SMMC-7721 cells. TGF-beta 1 could also promote cell migration. Furthermore, our results showed that TGF-beta1 treatment stimulated the tyrosine phosphorylation level of FAK, which can be activated by the ligation and clustering of integrins. PTEN can directly dephosphorylate FAK, and the results that TGF-beta 1 could down-regulate PTEN at protein level suggested that TGF-beta 1 might stimulate FAK phosphorylation through increasing integrin signaling and reducing dephosphorylation of FAK. These studies indicated that TGF-beta 1 and integrin-mediated signaling act synergistically to enhance cell adhesion and migration and affect downstream signaling molecules of hepatocarcinoma cells.

Clinical evaluation of the automated COBAS AMPLICOR HCV MONITOR test version 2.0 for quantifying serum hepatitis C virus RNA and comparison to the quantiplex HCV version 2.0 test

A second-generation hepatitis C virus (HCV) quantitative assay (COBAS AMPLICOR HCV MONITOR Test, version 2.0; COBAS HCM-2) has been developed, with the intention of achieving equivalent quantification of all HCV genotypes and improving assay performance. To evaluate the clinical performance of COBAS HCM-2 and its utility in predicting the response to alpha interferon treatment, sera from 215 chronic hepatitis C patients were analyzed and the results were compared with those obtained by the Quantiplex bDNA HCV RNA, version 2.0, assay (bDNA-2). The COBAS HCM-2 had significantly greater sensitivity than bDNA-2 (94.9 versus 88.4%; P < 0.001) when performed with sera from chronic hepatitis C patients who were viremic by a qualitative PCR test. The standard deviations for the within-run and between-run reproducibilities of COBAS HCM-2 were <0. 1 and <0.2, respectively, and it showed an improved linear range between genotypes with the threefold serial dilutions tested (r(2) = 0.986 to 0.995). The COBAS HCM-2 results were positively correlated with the bDNA-2 results, but the values for COBAS HCM-2 were on average 0.96 log lower than the values for bDNA-2. The mean difference in quantification values between these two assays did not differ among samples with different genotypes (0.70 to 1.00 log). No genotype-dependent difference in viral load was observed. The pretreatment viral load was significantly lower in complete responders. By using multivariate analysis, the viral load 2 weeks after the initiation of alpha interferon treatment was the strongest predictor of a complete response. In conclusion, COBAS HCM-2 demonstrated good sensitivity, linearity, and reproducibility and efficiency equal to that of bDNA-2 for the quantification of HCV genotypes 1 and 2. Hence, this assay provides a rapid and reliable method for the quantification of HCV RNA in serum and is useful for the planning of interferon treatment.

Percutaneous ethanol injection of the supplying artery to hepatocellular carcinoma that is not amenable to conventional treatment

The purpose of this study was to evaluate the clinical usefulness of ultrasound-guided percutaneous ethanol injection of the supplying artery (PEISA) to the tumour in the palliative management of hepatocellular carcinoma (HCC) that is not amenable to conventional treatments. A total of 23 cases of HCC, measuring from 3.1 cm to larger than 15 cm (median 5.4 cm) in 17 cirrhotic patients, were treated by PEISA. PEISA was used to control rapid growth of the tumour in seven patients and to reduce abdominal discomfort caused by rapid expansion of the tumour in 10 patients. Tumours with arterial Doppler signals persisting after PEISA underwent repeated treatment. The follow-up period ranged from 2-48 months. PEISA was achieved in 69 out of 76 attempts (90.8%). The amount of ethanol injected on each occasion ranged from 2.5-33 ml. Follow-up colour Doppler scanning showed complete elimination of tumour Doppler signals in 22 out of 23 lesions (95.7%). Following treatment, one tumour disappeared, 13 tumours shrank and nine tumours were unchanged in size. All patients with abdominal discomfort had relief after treatment. The common complications of PEISA were local pain and fever. In conclusion, PEISA is effective at treating painful HCC unsuitable for conventional treatment.

Serotyping and genotyping of hepatitis C virus in Taiwanese patients with type C chronic liver disease and uraemic patients on maintenance haemodialysis

BACKGROUND

To evaluate a recombinant immunoblot hepatitis C virus (HCV) serotyping assay, which determines HCV serotypes 1, 2, and 3 by detecting type-specific antibodies to core-and NS-4-derived peptides.

METHODS

Immunoreactivity of type-specific antibodies among 173 chronic hepatitis C patients and 43 haemodialysis patients in Taiwan was examined and the serotyping results were compared with genotyping by Okamoto's method. Serial specimens from 29 patients undergoing interferon-alpha therapy were also evaluated.

RESULTS

Of the 205 specimens for which genotyping data were available, 51.2% were of serotype 1, 31.7% of serotype 2, 1.0% of serotype 3, 2.4% of either serotype 1 or 3, and the remaining 13.7% were untypable. The serotypable rate was significantly lower in haemodialysis patients than in chronic hepatitis C patients (70.0% vs 94.9%; P < 0.001). Serotyping of genotype 2b specimens was significantly more dependent on core peptide bands than other genotypes. Using genotyping as the reference, the overall sensitivity, specificity and concordance of the recombinant immunoblot HCV serotyping assay were 86.3%, 97.2% and 83.9%, respectively. However, the serotyping assay had significantly lower sensitivity (69.2%), specificity (77.8%) and concordance (53.8%) for genotype 2b specimens. Of nine HCV complete responders, one lost type-specific antibodies 6 months after the cessation of interferon-alpha treatment.

CONCLUSIONS

These results suggest that, except for less than optimal performance with immunocompromised or genotype 2b patients, the HCV serotyping assay is a practical and useful method for HCV typing in the clinical setting in Taiwan.

Epidemiology of hepatitis B virus infection in the Asia-Pacific region

There is a wide variation of hepatitis B virus (HBV) infection in the Asia-Pacific region. The prevalence of chronic HBV infection is lowest (<1%) in North America, Australia and New Zealand, 2-4% in Japan, 5-18% in China and highest (15-20%) in Taiwan as well as several other countries in South East Asia. Perinatal transmission is common in HBV-hyperendemic areas. Geographical clusters of horizontal HBV infection have been reported in both high- and low-risk countries. Common sources of infection, including iatrogenic and sexual transmission, have been implicated. Migrant studies indicate the importance of childhood environments in the determination of HBV infection. Rural urban and ethnic differences in the prevalence of HBV infection have also been reported. There has been a decrease in the prevalence of HBV infection after mass HBV vaccination programmes in some Asia-Pacific countries, which may be due to the intervention of possible transmission routes through the use of disposable syringes and needles, screening of HBV infection markers in blood banks, and prevention of high-risk tattooing, acupuncture, ear-piercing and sexual contact. A striking decrease in the incidence of HBV infection and hepatocellular carcinoma has been observed among children in Taiwan and other areas where mass vaccination programmes have been implemented.

Virologic factors related to interferon-alpha-induced thyroid dysfunction in patients with chronic hepatitis C

OBJECTIVE

Hepatitis C virus (HCV), being reported to be associated with a high prevalence of serological markers of autoimmunity in HCV-infected patients, and possibly sharing partial sequences in amino acid segments with thyroid tissue antigens, may be associated with interferon-alpha (IFN-alpha)-induced thyroid dysfunction in chronic hepatitis C patients. We conducted this study to clarify the issue.

DESIGN AND METHODS

One hundred and fifty chronic hepatitis C patients with normal baseline thyroid function were treated with IFN-alpha 2a, 2b and n1 (3-6 million Units three times weekly for 24 weeks). Pretreatment sera were tested for HCV genotype and HCV RNA levels. Serum thyrotropin, total thyroxine and free thyroxine index were performed every 4 weeks for 24 weeks followed by every 8 weeks for another 24 weeks.

RESULTS

Twenty-one (14.0%) patients developed early thyroid dysfunction (abnormal thyroid function during the first 3 months of therapy). Female gender, lower HCV RNA levels, IFN-alpha n1 and a lower IFN-alpha dose were significantly associated with early thyroid dysfunction. On multivariate analysis, gender, IFN-alpha preparation and HCV RNA levels were the significant factors associated with early thyroid dysfunction. Seven (4.7%) patients developed thyroid dysfunction during the second 3 months of IFN-alpha therapy. Taken together, 18.7% patients developed thyroid dysfunction. Female, mixed HCV genotype infection and lower HCV RNA levels were significantly associated with thyroid dysfunction. However, only gender remained significantly associated with IFN-alpha-induced thyroid dysfunction in multivariate analysis.

CONCLUSIONS

The virologic features of HCV may be associated with thyroid dysfunction in chronic hepatitis C patients treated with IFN-alpha. Nevertheless, gender still plays the most important role in IFN-alpha-induced thyroid dysfunction.

Role of serum C-reactive protein as a marker of hepatocellular carcinoma in patients with cirrhosis

BACKGROUND

The usefulness of C-reactive protein (CRP) as a tumour marker in patients with hepatocellular carcinoma (HCC) is controversial. The purpose of this study was to determine whether CRP estimation could be used to identify patients with HCC among those with cirrhosis.

METHODS

Serum levels of CRP and alpha-fetoprotein (AFP) were investigated in 122 previously untreated patients with cirrhosis and HCC. Another 76 patients with cirrhosis alone were also investigated as controls.

RESULTS

Of the subjects tested, 47.5% of patients with HCC and 39.5% of controls had elevated CRP values (> 6 microg/mL). Although using elevated CRP and/or AFP (> 20 ng/mL) as a criterion showed a significant difference between controls and patients with multiple nodular, massive, or diffuse type HCC (all P < 0.005), the clinical application of this criterion was limited because of low specificity (58%) and accuracy (all < 73%). By using receiver-operating characteristic curves no valuable threshold value of CRP was found to discriminate various types of HCC, except for distinguishing the diffuse type from controls. The CRP value of 12 microg/mL could be used as the cut-off value to differentiate diffuse-type HCC from controls (sensitivity 82.4%, specificity 82%, accuracy 82.1%, P<0.005).

CONCLUSIONS

Serum CRP is not a good marker for HCC. However, very high values of CRP in patients with cirrhosis may suggest the presence of a diffuse-type HCC.

Heterogeneous conductance levels of native AMPA receptors

The single-channel properties of AMPA receptors can affect information processing in neurons by influencing the amplitude and kinetics of synaptic currents, yet little is known about the unitary properties of native AMPA receptors in situ. Using whole-cell and outside-out patch-clamp recordings from granule cells in acute cerebellar slices, we found that migrating granule cells begin to express AMPA receptors before they arrive in the internal granule cell layer and receive synaptic input. At saturating agonist concentrations, the open probability of channels in outside-out patches from migrating cells was very high, allowing us to identify patches that contained only one or two active channels. Analysis of the single-channel activity in these patches showed that individual AMPA receptors exhibit as many as four distinguishable conductance levels. The conductance levels observed varied substantially for different channels, although on average the values fell within the range of unitary conductances estimated previously for synaptic AMPA receptors. In contrast to patches from migrating granule cells, we rarely observed directly resolvable single-channel currents in patches excised from the somata of granule cells in the internal granular layer, even though these cells gave large AMPA receptor whole-cell currents. We did, however, detect AMPA receptors with apparent unitary conductances of <1 pS in patches from both migrating and mature granule cells. Our results suggest that granule cells express a heterogeneous population of AMPA receptors, a subset of which are segregated to postsynaptic sites after synaptogenesis.

Esterase-sensitive nitric oxide donors of the diazeniumdiolate family: in vitro antileukemic activity

We have designed a novel prodrug class that is stable in neutral aqueous media but releases bioactive nitric oxide (NO) on metabolism by esterase. Diazeniumdiolates of structure R(2)N-N(O)=N-OR', in which R' = Na, were reacted with BrCH(2)OAc to convert the spontaneously NO-releasing salts 1a (R(2)N = diethylamino) and 1b (R(2)N = pyrrolidino) to prodrugs 2a (AcOM-DEA/NO) and 2b (AcOM-PYRRO/NO), respectively, where R' = CH(2)OAc. In contrast to anions 1a and 1b (half-lives in pH 7.4 phosphate at 37 degrees C of 2 min and 3 s, respectively), 2a and 2b showed only minimal decomposition after 16 h under these conditions. Very rapid hydrolysis occurred in the presence of porcine liver esterase, however, with free anion 1a being observed as an intermediate in the esterase-induced generation of NO from 2a. The potential utility of this prodrug class is illustrated with a comparison of 1 and 2 as antiproliferative agents in NO-sensitive human leukemia cell lines HL-60 and U937. While the 72-h IC(50)'s for 1a and 1b (which generate NO throughout the medium) in HL-60 cell cultures were >600 microM, those of 2a and 2b were 8.3 and 6.4 microM, respectively. This result is consistent with our hypothesis that 2 is selectively hydrolyzed to 1 and thence to NO intracellularly. For U937 cells, the 72-h IC(50) for both 2a and 2b was 53 microM. By contrast, relatively high antiproliferative IC(50)'s (>100 microM in U937 cells) were observed for analogues in which R' = CH(2)CH(2)SC(O)Me, from which acetyl and 2-mercaptoethyl groups must be successively cleaved to free the NO-releasing diazeniumdiolate function. Within 24 h at initial concentrations of 50 microM, 2a and 2b induced apoptosis in 50% and 57% of the HL-60 cells, respectively (35% and 40% of the U937 cells, respectively). The data reveal significant in vitro antileukemic activity on the part of these novel compounds. Moreover, their substantial ease-of-handling advantages over the anionic diazeniumdiolates from which they are derived suggest their use as convenient agents for probing the biological roles of NO.

Clinical application of the Quantiplex HCV RNA 2.0 and Amplicor HCV Monitor assays for quantifying serum hepatitis C virus RNA

AIM

To compare the performance characteristics and clinical application of two different technologies for quantifying serum hepatitis C virus (HCV) RNA levels.

METHODS

HCV RNA was quantified by Amplicor HCV Monitor assay (Amplicor) and Quantiplex HCV RNA 2.0 assay (bDNA-2) in 119 sera from 107 HCV infected patients.

RESULTS

Both assays had similar sensitivity (79.4% for Amplicor; 86.0% for bDNA-2), acceptable coefficients of variation (5.3% in Amplicor; 2.6% in bDNA-2), and good linearity (r2 > or = 0.98). There was a positive correlation between quantification values of both methods (r = 0.683, p < 0.001). The Amplicor values were on an average 1.76 log lower than bDNA-2 results. Male subjects and HCV genotype 1b were significantly associated with higher viral load determined by Amplicor, but not with viral load measured by bDNA-2. In 70 chronic HCV infected patients treated with interferon alfa, mean (SD) pretreatment viral load in 27 complete responders (3.47 (0.84) logs for Amplicor, 5.63 (0.58) for bDNA-2) was significantly lower than in non-responders (4.43 (1.01) logs for Amplicor, 6.10 (0.67) logs for bDNA-2; p < 0.001). Cut off points of 3.9 logs for Amplicor and 5.8 logs for bDNA-2 were determined to be the best for predicting response to interferon alfa, giving acceptable sensitivity (70.4%, 74.1%), specificity (72.1%, 65.1%), and accuracy (71.4%, 68.6%), respectively.

CONCLUSIONS

Both the Amplicor and bDNA-2 assays are clinically useful methods for HCV RNA quantification and are reliable for predicting the outcome of treatment, despite differences in absolute quantification values and in the correlation between HCV genotypes and viral load.

Redox imbalance differentially inhibits lipopolysaccharide-induced macrophage activation in the mouse liver

Endotoxemia is accompanied by significant changes in the reductive-oxidative (redox) balance of critical target organs. Redox stress has been shown to regulate the expression of proinflammatory genes that are induced by endotoxic lipopolysaccharide (LPS) in vitro; however, much less is known about the effects of redox imbalance on LPS-induced gene expression in vivo. To assess the effects of redox stress on inflammatory responses in endotoxemia, mice were treated with either diethyl maleate (DEM), a glutathione-depleting agent, or buthionine sulfoximine (BSO), an inhibitor of glutathione synthesis, and challenged with LPS. While serum tumor necrosis alpha (TNF-alpha) responses and the appearance of TNF-alpha-positive Kupffer cells in the liver were virtually eliminated by DEM or BSO treatment, the expression of both CD14 and inducible NO synthase (iNOS) by Kupffer cells was unaffected by glutathione depletion. By contrast, LPS-induced hepatocyte and hepatic sinusoidal endothelial cell iNOS expression was significantly inhibited in DEM-treated mice. Hepatocyte iNOS induced by recombinant mouse TNF-alpha was also inhibited by DEM treatment. These results indicate that the effects of oxidative stress in this organ are cell type specific and suggest that both the production and the action of TNF-alpha are substantially influenced by the redox state of the liver during endotoxemia.

Distinct kainate receptor phenotypes in immature and mature mouse cerebellar granule cells

1. Although glutamate receptors have been shown to be involved in neuronal maturation, a developmental role for kainate-type receptors has not been described. In addition, the single-channel properties of native kainate receptors have not been studied in situ. We have characterized the electrophysiological properties of native kainate receptors of granule cell neurons at two distinct stages in postnatal development, using whole-cell and outside-out patch-clamp recordings in acute cerebellar slices. 2. Kainate-type currents were detected in both immature and mature granule cells. However, noise analysis showed that the apparent unitary conductance of kainate-type channels is significantly higher in proliferating than post-migratory granule cells. The conductance and rectification behaviour of the channels in immature granule cells indicate that they contain unedited GluR5 and GluR6 subunits and are likely to be calcium permeable. 3. Single-channel kainate-type currents were observed in outside-out patches from proliferating granule cells in the external germinal layer. The kinetic behaviour of kainate receptors in immature cells was complex. Openings to multiple conductance levels were observed, although our analysis indicates that the channels spend most of their open time in a 4 pS state.

Infection with a recombinant vaccinia virus encoding myelin proteolipid protein causes suppression of chronic relapsing-remitting experimental allergic encephalomyelitis

Mice infected with a recombinant vaccinia virus (VVplp) encoding the myelin proteolipid protein (PLP) and then challenged with the encephalitogenic peptide, PLP139-151, developed a more severe acute attack vs. control mice. Following this initial acute attack, vaccinated mice had significantly less clinical disease (relapses) than control vaccinated or mock vaccinated mice. Control mice developed a relapsing-remitting disease with severe clinical relapses. During the remission state in VVplp vaccinated mice, histopathologic changes were markedly reduced in the central nervous system (CNS) vs. control vaccinated or unvaccinated mice. Inflammation was mainly limited to the meninges with a reduction of mononuclear cells in the parenchyma of the spinal cord in VVplp vaccinated and PLP139-151 challenged mice vs. control mice where inflammatory changes with demyelination was observed. During the remission period an increase in IL-4 was seen. In addition, there was significantly less T cell proliferation to PLP139-151 that was confirmed by an in vivo measurement of T cell reactivity, DTH responses. This suggests that the almost permanent remission state was dictated by a decreased responsiveness to PLP139-151 in VVplp vaccinated mice.

The role of resource allocation models in selecting clinical preventive services

OBJECTIVE

To demonstrate the potential value and current limitations of using resource allocation models for selecting health services.

DESIGN

To identify the most efficient mix of preventive services that could be offered by a managed care organization (MCO) for a fixed budget, an optimization model (greatest number of life years saved) and a cost-effectiveness model (rank order of most to least cost effective) were developed. Because of the lack of cost-effectiveness analyses that met the study criteria, only 9 preventive services were selected to demonstrate each model.

PATIENTS AND METHODS

The 2 models were applied to a hypothetical managed care population of 100,000 enrollees with age, sex, and risk distribution similar to that of the US population. Data for the input variables were obtained from cost-effectiveness studies of 9 preventive services. Model variables included the target population, percent of enrollees who received the preventive service, the cost of the preventive service, life years saved, and cost-effectiveness ratios.

RESULTS

The models demonstrated that efficient allocation of finite resources can be achieved. When budgets are limited, different premises between the 2 models may yield different health consequences. However, as the budgets were increased, results from the 2 models were more closely aligned.

CONCLUSIONS

Resource allocation models have the potential for assisting MCOs in selecting a set of preventive services that will maximize population health. Before this potential can be fully realized, additional methodological development and cost-effectiveness studies are needed. The use of resource allocation should be examined for selecting all healthcare services.

Regulation of N-methyl-D-aspartate receptor function by constitutively active protein kinase C

The ability of the constitutively active fragment of protein kinase C (PKM) to modulate N-methyl-D-aspartate (NMDA)-activated currents in cultured mouse hippocampal neurons and acutely isolated CA1 hippocampal neurons from postnatal rats was studied using patch-clamp techniques. The responses of two heterodimeric combinations of recombinant NMDA receptors (NR1a/NR2A and NR1a/NR2B) expressed in human embryonic kidney 293 cells were also examined. Intracellular applications of PKM potentiated NMDA-evoked currents in cultured and isolated CA1 hippocampal neurons. This potentiation was observed in the absence or presence of extracellular Ca2+ and was prevented by the coapplication of the inhibitory peptide protein kinase inhibitor(19-36). Furthermore, the PKM-induced potentiation was not a consequence of a reduction in the sensitivity of the currents to voltage-dependent blockade by extracellular Mg2+. We also found different sensitivities of the responses of recombinant NMDA receptors to the intracellular application of PKM. Some potentiation was observed with the NR1a/NR2A subunits, but none was observed with the NR1a/NR2B combination. Applications of PKM to inside-out patches taken from cultured neurons increased the probability of channel opening without changing single-channel current amplitudes or channel open times. Thus, the activation of protein kinase C is associated with potentiation of NMDA receptor function in hippocampal neurons largely through an increase in the probability of channel opening.

Formation of intermediate-conductance calcium-activated potassium channels by interaction of Slack and Slo subunits

Large-conductance calcium-activated potassium channels (maxi-K channels) have an essential role in the control of excitability and secretion. Only one gene Slo is known to encode maxi-K channels, which are sensitive to both membrane potential and intracellular calcium. We have isolated a potassium channel gene called Slack that is abundantly expressed in the nervous system. Slack channels rectify outwardly with a unitary conductance of about 25-65 pS and are inhibited by intracellular calcium. However, when Slack is co-expressed with Slo, channels with pharmacological properties and single-channel conductances that do not match either Slack or Slo are formed. The Slack/Slo channels have intermediate conductances of about 60-180 pS and are activated by cytoplasmic calcium. Our findings indicate that some intermediate-conductance channels in the nervous system may result from an interaction between Slack and Slo channel subunits.

High-frequency firing helps replenish the readily releasable pool of synaptic vesicles

Synapses in the central nervous system undergo various short- and long-term changes in their strength, but it is often difficult to distinguish whether presynaptic or postsynaptic mechanisms are responsible for these changes. Using patch-clamp recording from giant synapses in the mouse auditory brainstem, we show here that short-term synaptic depression can be largely attributed to rapid depletion of a readily releasable pool of vesicles. Replenishment of this pool is highly dependent on the recent history of synaptic activity. High-frequency stimulation of presynaptic terminals significantly enhances the rate of replenishment. Broadening the presynaptic action potential with the potassium-channel blocker tetraethylammonium, which increases Ca2+ entry, further enhances the rate of replenishment. As this increase can be suppressed by the Ca2+-channel blocker Cd2+ or by the Ca2+ buffer EGTA, we conclude that Ca2+ influx through voltage-gated Ca2+ channels is the key signal that dynamically regulates the refilling of the releasable pool of synaptic vesicles in response to different patterns of inputs.

Contribution of the Kv3.1 potassium channel to high-frequency firing in mouse auditory neurones

1. Using a combination of patch-clamp, in situ hybridization and computer simulation techniques, we have analysed the contribution of potassium channels to the ability of a subset of mouse auditory neurones to fire at high frequencies. 2. Voltage-clamp recordings from the principal neurones of the medial nucleus of the trapezoid body (MNTB) revealed a low-threshold dendrotoxin (DTX)-sensitive current (ILT) and a high-threshold DTX-insensitive current (IHT). 3. IHT displayed rapid activation and deactivation kinetics, and was selectively blocked by a low concentration of tetraethylammonium (TEA; 1 mM). 4. The physiological and pharmacological properties of IHT very closely matched those of the Shaw family potassium channel Kv3.1 stably expressed in a CHO cell line. 5. An mRNA probe corresponding to the C-terminus of the Kv3.1 channel strongly labelled MNTB neurones, suggesting that this channel is expressed in these neurones. 6. TEA did not alter the ability of MNTB neurones to follow stimulation up to 200 Hz, but specifically reduced their ability to follow higher frequency impulses. 7. A computer simulation, using a model cell in which an outward current with the kinetics and voltage dependence of the Kv3.1 channel was incorporated, also confirmed that the Kv3.1- like current is essential for cells to respond to a sustained train of high-frequency stimuli. 8. We conclude that in mouse MNTB neurones the Kv3.1 channel contributes to the ability of these cells to lock their firing to high-frequency inputs.

Inhibitory effect of linoleic acid on chain elongation and desaturation of 18:2 c,t isomers in lactating and neonatal rats

The previous studies showed that dietary 18:2 c,t isomers could be chain-elongated and desaturated to produce unusual 20:4 isomers. The present study was undertaken to determine the minimal amount of 18:2n-6 required to suppress the chain elongation and desaturation of 18:2 c,t isomers in the lactating and neonatal rats when animals were fed 15% partially hydrogenated canola oil diet containing 1.72% energy as 18:2 c,t isomers and varying amounts of free 18:2n-6. These diets induced marginal essential fatty acid (EFA) deficiency states (0.56% energy 18:2n-6) to EFA adequacy (2.56% energy 18:2n-6). After feeding for 50 d, the female animals were mated with males by overnight pairing. After conception, the lactating rats were killed, together with one pup from each dam, at term and day 26 of lactation. Two unusual 20:4 isomers in both maternal and neonatal liver phospholipids were identified as 20:4delta5c,8c,11c,14t and 20:4delta5c,8c,11c,15t, which were derived from 18:2delta9c,12t and 18:2delta9c,13t, respectively. The results showed that 18:2n-6 at about 2.0% of total energy in maternal diet was required to block the production of 20:4delta5c,8c,11c,14t and 20:4delta5c,8c,11c,15t in the maternal liver, whereas 18:2n-6 at about 2.5% of total energy in maternal diet was required to suppress production of these unusual 20:4 isomers in the neonatal liver.

Activation of Kv3.1 channels in neuronal spine-like structures may induce local potassium ion depletion

Spines are specialized neuronal membrane structures, often localized at sites where synaptic information is relayed from one cell to another in the central nervous system. By electron immunomicroscopy we have found that the mammalian Shaw family potassium channel Kv3.1 is localized on spine-like protrusions, adjacent to postsynaptic membranes of bushy cells in the cochlear nucleus. As direct characterization of the electrophysiological behavior of ion channels in such structures is difficult, we have used Kv3. 1-transfected CHO cells to create artificial spine-like membrane compartments. Membrane patches were sucked into microelectrodes to form small, cell-attached vesicles with dimensions comparable to those of the neuronal structures. Currents mediated by the Kv3.1 channel in these vesicles undergo rapid and complete inactivation, in contrast to their noninactivating behavior in whole-cell recordings. This apparent inactivation is caused by the rapid depletion of K+ from the vesicle and the slow refilling of K+ into the vesicle compartment from the bulk cytoplasm. Our data provide evidence that compartmentalized ionic transients can be generated in spine-like membrane structures and support the view that the localization of ion channels in spine-like structures may influence responses to synaptic stimulation.

4-Aminobiphenyl DNA damage in liver tissue of hepatocellular carcinoma patients and controls

Epidemiologic studies have suggested that cigarette smoking is a risk factor for the development of hepatocellular carcinoma (HCC). To further investigate this relation, the authors measured levels of 4-aminobiphenyl-DNA adducts by an immunoperoxidase method in surgical liver tissues obtained between 1984 and 1995 from 105 Taiwanese patients with histologically confirmed HCC and 37 Taiwanese patients with metastatic liver tumors or intrahepatic stones. Information on clinicopathologic characteristics, cigarette smoking, and alcohol drinking was abstracted from hospital charts. Mean relative staining intensity for 4-aminobiphenyl-DNA was slightly higher in tumor tissues than in nontumor tissues obtained from HCC patients. Both mean intensities were significantly higher than the mean intensity of control tissues taken from non-HCC patients. However, no difference in mean relative staining intensity was found between smokers and nonsmokers in tissues obtained from non-HCC patients, or in tumor or nontumor tissues taken from HCC cases. After stratification of the relative staining intensities of 4-aminobiphenyl-DNA adduct levels into tertiles according to the total numbers of control tissues analyzed, there was a monotonically increasing risk of HCC. Odds ratios were 4.14 (95% confidence interval (CI) 1.15-15.50) and 9.71 (95% CI 2.82-34.86) for medium and high adduct levels compared with low adduct levels, respectively. The linear relation between adduct levels in liver tissue and HCC risk was also significant after adjustment for covariates, including hepatitis B surface antigen (HBsAg) status. The multivariate adjusted odds ratios were 3.41 (95% CI 0.82-14.25) and 6.48 (95% CI 1.59-26.50) for medium and high adduct levels, respectively. Moreover, there were monotonically increasing HCC risks for higher adduct levels in both HBsAg carriers and noncarriers. The increased risk ratios were more pronounced in noncarriers than in carriers. However, because of the small numbers of subjects, especially controls positive for HBsAg, the interaction between HBsAg status and 4-aminobiphenyl-DNA adduct level was not significant. Among HCC cases, none of the clinicopathologic characteristics were associated with relative staining intensity. These results indicate that 4-aminobiphenyl exposure, which is primarily a result of cigarette smoking, plays a role in the development of HCC in humans.