Cost-effectiveness analysis of tenofovir disoproxil fumarate for treatment of chronic hepatitis B in China.

BACKGROUND: Tenofovir disoproxil fumarate (TDF) is newly available for treatment of chronic hepatitis B patients in China. To date, no study has been conducted to examine the cost-effectiveness of this treatment. The aim of this study was to estimate the cost-effectiveness of TDF versus four oral nucleos(t)ide analogs [lamivudine (LAM), adefovir (ADV), telbivudine (LdT), and entecavir (ETV)] and from a pharmacoeconomic perspective to assess current drug pricing for TDF. METHODS: Based on Chinese healthcare perspectives, a Markov model was applied to simulate the lifetime (40-year time span) costs and quality-adjusted life-years (QALYs) for five different monotherapy strategies. Two kinds of rescue combination strategies (base-case: LAM + ADV then ETV + ADV; alternative: directly using ETV + ADV) were separately considered for treatment of patients refractory to monotherapy. Model parameters (including disease transition, cost, and utility) were obtained from previous Chinese population studies. Both branded and generic drugs were separately analyzed. Study model uncertainties were assessed by one-way and probabilistic sensitivity analyses. Two-way sensitivity analysis was used to explore uncertainties between efficacy and price of TDF. RESULTS: In the base-case analysis, the lowest lifetime cost and the best cost-effectiveness ratio were obtained by ETV, which was considered the reference treatment. LAM, ADV, and LdT treatments had significantly greater costs and lower efficacies. Compared to ETV, TDF was more effective but also more expensive. The incremental cost-effectiveness ratios of TDF versus ETV were much higher than the willing-to-pay threshold of $20,466 US dollars (USD) per QALY gained (3 × gross domestic product per capita of China, 2014). TDF would be the most cost-effective strategy if the annual cost did not exceed $2260 USD and $1600 USD for branded and generic drugs, respectively. CONCLUSIONS: For Chinese chronic hepatitis B patients, ETV is still the most cost-effective strategy over TDF and other nucleos(t)ide analogs, with a threshold of $20,466 USD/QALY gained.

Cost-effectiveness of Lamivudine, Telbivudine, Adefovir Dipivoxil and Entecavir on decompensated hepatitis B virus-related cirrhosis.

OBJECTIVE: To evaluate the cost-effectiveness of lamivudine (LMV), telbivudine (LdT), adefovir dipivoxil (ADV) and entecavir (ETV) on decompensated hepatitis B virus-related cirrhosis. PATIENTS AND METHODS: 1332 patients with decompensated hepatitis B virus-related cirrhosis were randomly assigned into 5 groups with different clinical treatment including LMV treatment, LdT treatment, ADV treatment, LMV+ADV treatment and ETV treatment. And then the liver function, Child-Pugh scores, sero-conversion of HBeAg/HBeAb, polymerase gene mutations, cost-effectiveness, incremental cost-effectiveness and side effects were investigated and further analyzed. RESULTS: LMV, ADV, LdT, LMV+ADV and ETV were all effective on decreasing Child-Pugh scores and conversing negatively hepatitis B virus (HBV) DNA and HBeAg, whereas LMV+ADV and ETV more effective than LMV, ADV and LdT. HBV DNA polymerase genotypic mutations were rare in the 5 groups. The less mutation rate was found in the LMV+ADV and ETV group than in the LMV, ADV and LdT group. Compared to the cost-effectiveness and incremental cost-effectiveness ratio, ETV was the optimal selection, LMV+ADV was the alternative selection and LMV was the cheapest option. The side effects of the 5 plans were all rare and could be controlled. CONCLUSIONS: LMV, ADV, LdT, LMV+ADV and ETV were all effective on treatment of decompensated hepatitis B virus-related cirrhosis whereas ETV and LMV+ADV were recommended.

Cost-effectiveness analysis of lamivudine, telbivudine, and entecavir in treatment of chronic hepatitis B with adefovir dipivoxil resistance.

The purpose of this study was to analyze the cost-effectiveness of lamivudine (LMV), telbivudine (LdT), and entecavir (ETV) in treatment of chronic hepatitis B with adefovir dipivoxil (ADV) resistance. Two hundred and fifty-two patients were recruited and screened for resistance to ADV and randomly assigned into three groups: LMV + ADV, LdT + ADV, and ETV + ADV. The ratio of biochemical response, virological response, seroconversion of hepatitis Be antigen (HBeAg)/hepatitis Be antibody (HBeAb), viral breakthrough, and the cost and effectiveness of treatments were analyzed. A comparison of the results of the ratio of biochemical response, virological response and seroconversion of HBeAg/HBeAb, showed no statistical difference between the three groups, with the economic cost of LMV + ADV the lowest, LdT + ADV the middle, and ETV + ADV the highest. The side effects of the three plans are all rare and tolerable. LMV + ADV is the optimal rescue strategy, and LdT + ADV the alternative selection in the economically less developed regions, while ETV + ADV was used in the economically developed regions.

Quantitative assessment of Tet-induced oxidation products of 5-methylcytosine in cellular and tissue DNA.

Recent studies showed that Ten-eleven translocation (Tet) family dioxygenases can oxidize 5-methyl-2'-deoxycytidine (5-mdC) in DNA to yield the 5-hydroxymethyl, 5-formyl and 5-carboxyl derivatives of 2'-deoxycytidine (5-HmdC, 5-FodC and 5-CadC). 5-HmdC in DNA may be enzymatically deaminated to yield 5-hydroxymethyl-2'-deoxyuridine (5-HmdU). After their formation at CpG dinucleotide sites, these oxidized pyrimidine nucleosides, particularly 5-FodC, 5-CadC, and 5-HmdU, may be cleaved from DNA by thymine DNA glycosylase, and subsequent action of base-excision repair machinery restores unmethylated cytosine. These processes are proposed to be important in active DNA cytosine demethylation in mammals. Here we used a reversed-phase HPLC coupled with tandem mass spectrometry (LC-MS/MS/MS) method, along with the use of stable isotope-labeled standards, for accurate measurements of 5-HmdC, 5-FodC, 5-CadC and 5-HmdU in genomic DNA of cultured human cells and multiple mammalian tissues. We found that overexpression of the catalytic domain of human Tet1 led to marked increases in the levels of 5-HmdC, 5-FodC and 5-CadC, but only a modest increase in 5-HmdU, in genomic DNA of HEK293T cells. Moreover, 5-HmdC is present at a level that is approximately 2-3 and 3-4 orders of magnitude greater than 5-FodC and 5-CadC, respectively, and 35-400 times greater than 5-HmdU in the mouse brain and skin, and human brain. The robust analytical method built a solid foundation for dissecting the molecular mechanisms of active cytosine demethylation, for measuring these 5-mdC derivatives and assessing their involvement in epigenetic regulation in other organisms and for examining whether these 5-mdC derivatives can be used as biomarkers for human diseases.

Lung cancer biomarkers for the assessment of modified risk tobacco products: an oxidative stress perspective.

Manufacturers have developed prototype cigarettes yielding reduced levels of some tobacco smoke toxicants, when tested using laboratory machine smoking under standardised conditions. For the scientific assessment of modified risk tobacco products, tests that offer objective, reproducible data, which can be obtained in a much shorter time than the requirements of conventional epidemiology are needed. In this review, we consider whether biomarkers of biological effect related to oxidative stress can be used in this role. Based on published data, urinary 8-oxo-7,8-dihydro-2-deoxyguanosine, thymidine glycol, F2-isoprostanes, serum dehydroascorbic acid to ascorbic acid ratio and carotenoid concentrations show promise, while 4-hydroxynonenal requires further qualification.

A pilot study for the early assessment of the effects of BMS-754807 plus gefitinib in an H292 tumor model by [(18)F]fluorothymidine-positron emission tomography.

BMS-754807 is an inhibitor of insulin-like growth factor-1 receptor (IGF-1R) and insulin receptor that also represses aurora kinase. Cancers that express high levels of IGF-1/IGF-1R are sensitive to BMS-754807; however, it shows limited efficacy in non-small cell lung cancer (NSCLC) in which IGF-1R-driven signals may not be dominant factors in cell proliferation. In this study, we investigated whether a combination of BMS-754807 and gefitinib would be synergistic in H292 NSCLC and whether [(18)F]fluorothymidine ([(18)F]FLT)-positron emission tomography (PET) could predict the effects. We found that BMS-754807 synergized with gefitinib in reducing cell viability (combination index=0.38) and Akt phosphorylation, and increasing the subG1 fraction in H292 cells. BMS-754807 alone and in combination with gefitinib increased the cells in G2M phase and polyploid cells and decreased the phosphorylation of IGF-1R and histone H3. The inhibition of tumor growth by gefitinib was increased by BMS-754807 (%T/C, 17.5 % vs. 58.0 % for gefitinib alone and combined treatment, respectively), although BMS-754807 alone had little effect. The standardized uptake value by [(18)F]FLT-PET were increased in vehicle-treated mice by 73 %, minimally changed in gefitinib- or BMS-754807-treated mice, whereas decreased in co-treated mice by -48.8 % between day 0 and day 3. The combination therapy with BMS-754807 and gefitinib might be a more effective anticancer strategy than BMS-754807 alone in tumors that are less IGF-1R-dependent and that [(18)F]FLT-PET can be used to assess early therapeutic responses.

Cost-effectiveness of telbivudine versus lamivudine for chronic hepatitis B.

BACKGROUND AND AIM: Chronic hepatitis B is a highly prevalent disease worldwide, leading to serious consequences if not properly treated. Six treatment options for chronic hepatitis B are currently provided by the Brazilian public health system. Telbivudine is a nucleoside analogue that is neither included in the Brazilian clinical protocol nor in the therapeutic guidelines for chronic hepatitis B. OBJECTIVE: The aim of this study was to evaluate the cost-effectiveness of telbivudine for the viewpoint of the Brazilian public system, comparing it to lamivudine. METHODS: A Markov model was used to project lifetime complications and costs of treatment with lamivudine or telbivudine for chronic hepatitis B in both HBeAg-positive and HBeAg-negative patients. To evaluate disease progression, probabilities and utilities of virologic response, virologic resistance, compensated cirrhosis, decompensated cirrhosis, hepatocellular carcinoma, treatment, interruption of treatment, death and seroconversion were collected in systematic reviews. Costs were collected in DATASUS, ABC da Saúde and scientific literature. RESULTS: Higher rate of virologic response and seroconversion was obtained with telbivudine, and also higher values of quality adjusted life years. However lamivudine is associated with lower costs and also lower cost-effectiveness values. The incremental cost-effectiveness ratios for telbivudine, when compared with lamivudine, were US$ 30,575 and US$ 40,457, respectively for HBeAg-positive and HBeAg-negative patients. CONCLUSION: In chronic hepatitis B lamivudine is a more cost-effective or even cost-saving strategy when compared with telbivudine.

Cost-effectiveness of nucleoside analog therapy for hepatitis B in China: a Markov analysis.

OBJECTIVES: The aim of this study was to investigate the economic consequences of nucleoside analog therapy for hepatitis B treatment in China. METHODS: A cost-utility analysis of treatments for HBeAg-positive and HBeAg-negative chronic hepatitis B (CHB) was conducted using a Markov model, in which patients' yearly transitions between different health states were tracked. Patients were tracked as they moved between the following health states: CHB, HBeAg seroconversion (HBeAg-positive CHB patients can have this special health state), virologic resistance, virologic response, compensated cirrhosis, decompensated cirrhosis, hepatocellular carcinoma, liver transplantation, and death. The transition parameters were derived either from systematic reviews of the literature or from previous economic studies. Cost and utility data came from studies based on a Chinese CHB cohort. One-way sensitivity analyses as well as second-order Monte Carlo and probabilistic sensitivity analyses were performed. RESULTS: The entecavir strategy yielded the most quality-adjusted life years (QALYs) for both HBeAg-positive and HBeAg-negative patients when compared with the "no treatment," the lamivudine, the adefovir, and the telbivudine strategies. The risks of complications and mortality also decreased. In the economic analysis, the "no treatment" strategy was the least effective, whereas the entecavir strategy was both the least expensive and the most cost-effective option, followed by telbivudine and lamivudine. The probabilistic sensitivity analysis showed that the entecavir strategy would result in improved cost-effectiveness in >90% of cases at a threshold of $20,000 per QALY. In a one-way sensitivity analysis, the most influential parameters impacting the model's robustness were the utilities of the CHB and virologic response health states. CONCLUSIONS: In China, when treating both HBeAg-positive and HBeAg-negative CHB populations, entecavir is the most cost-effective option when compared with lamivudine, adefovir, and telbivudine.

Viral resistance in hepatitis B: prevalence and management.

Hepatitis B is a DNA virus affecting hundreds of millions of individuals worldwide. As the clinical sequelae of cirrhosis and hepatocellular cancer are increasingly recognized to be related to viral levels, the impetus increases to offer treatment to those previously not treated. With the development of more robust antivirals with reasonable safety profiles, long-term treatment is becoming more common. The oral nucleos(t)ide analogs have become the preferred first-line therapies for most genotypes of hepatitis B. Five are now available, all with different potencies and resistance profiles. Long-term data spanning several years are now available for most compounds in this arena. This article focuses on the common natural variants and those secondary to nucleos(t)ide therapy, as well as diagnostic methods to detect resistance.

Cost-effectiveness analysis of roadmap models in chronic hepatitis B using tenofovir as the rescue therapy.

BACKGROUND: The roadmap approach is recommended to guide chronic hepatitis B treatment. We evaluated the cost-effectiveness of various treatment strategies in the global market. METHODS: Lamivudine and telbivudine were tested in roadmap models with switch-to tenofovir if HBV was detectable at week 24 or add-on tenofovir if resistance developed at year 1. Tenofovir and entecavir were tested as continuous monotherapy. In the reference arm, lamivudine was used with add-on tenofovir if resistance developed at year 1. The primary measure of effectiveness was undetectable HBV DNA at year 2. Cost-effectiveness was measured by incremental cost-effectiveness ratio (ICER) in US dollars against the reference arm. RESULTS: In the US and Germany, costs of the reference arms were US $14,486 and US $9,998 for hepatitis B e antigen (HBeAg)-positive and US $11,398 and US $7,531 for HBeAg-negative patients, respectively. In HBeAg-positive patients, the lamivudine roadmap was most cost-effective (ICER US $15,260 in the US and US $29,113 in Germany) with comparable effectiveness (75.1%) to other strategies. In HBeAg-negative patients, tenofovir and entecavir monotherapies were most effective (91-96%) and cost-effective (ICER US $31,297-43,387 in the US and US $53,976-59,822 in Germany). In Asia, where telbivudine cost was lower, both telbivudine and lamivudine roadmaps were cost-effective in HBeAg-positive patients. Tenofovir would be most cost-effective in HBeAg-negative patients if its cost equaled that of telbivudine in Asia. CONCLUSIONS: In HBeAg-positive patients, lamivudine roadmap was most cost-effective; in Asia, telbivudine roadmap had comparable cost-effectiveness to lamivudine roadmap because of the relatively low price of telbivudine. In HBeAg-negative patients, entecavir and tenofovir monotherapies were more cost-effective than the roadmap models.

Telbivudine for the treatment of chronic hepatitis B infection.

This paper presents a summary of the evidence review group (ERG) report into the clinical effectiveness and cost-effectiveness of telbivudine for the treatment of chronic hepatitis B (CHB) in adults based upon a review of the manufacturer's submission to the National Institute for Health and Clinical Excellence (NICE) as part of the single technology appraisal (STA) process. The submission's evidence came from one randomised controlled trial (RCT) (GLOBE) of reasonable methodological quality comparing telbivudine with lamivudine. One other RCT that appeared to meet the inclusion criteria was excluded from the submission. For the primary outcome of therapeutic response telbivudine was statistically superior to lamivudine at weeks 52 and 104 for hepatitis B e antigen (HBeAg)-positive patients, and at week 104 for HBeAg-negative patients. There were statistically significant differences in favour of telbivudine for some secondary outcomes at 2 years including hepatitis B virus (HBV) DNA reduction, HBV DNA non-detectability and alanine aminotransferase normalisation though not for HBeAg-positive patients. In HBeAg-positive patients there was no significant difference between treatment groups for HBeAg loss or seroconversion at any time point. The incidence of adverse events was similar between treatments. Two RCTs comparing entecavir with lamivudine were included in the indirect comparison; however, this was poorly conducted and the results should be treated with caution. The manufacturer developed two economic models to determine the cost-effectiveness of telbivudine. Evidence on the efficacy of telbivudine and lamivudine was taken from the GLOBE trial; efficacy of adefovir was based on assumption. There was a lack of critical assessment and assurance of the quality of the data used to populate the models. The manufacturer concluded that telbivudine is a cost-effective option compared with lamivudine using evidence from the viral load model [HBeAg-positive patients/HBeAg-negative patients: mean incremental cost 19,087 pounds/49,003 pounds, mean quality-adjusted life-year (QALY) gain 1.30/4.67, incremental cost-effectiveness ratio (ICER) 14,665 pounds/10,497 pounds per QALY]. Resubmitted results after a request for clarification by the ERG gave less favourable ICERs (HBeAg-positive patients/HBeAg-negative patients: mean incremental cost 23,983 pounds/41,910 pounds, mean QALY gain 1.56/2.07, ICER 15,377 pounds/20,256 pounds per QALY). The manufacturer concluded that telbivudine is a cost-effective option (on its own or followed by adefovir) for patients who have developed resistance to first-line telbivudine treatment; however, the presentation of the results was not ideal. In conclusion, although telbivudine was statistically superior to lamivudine for most antiviral outcomes, the difference was not clinically significant; in addition, the cost-effectiveness evidence for telbivudine presented in the manufacturer's submission was limited. The NICE guidance issued as a result of the STA states that telbivudine is not recommended for the treatment of chronic hepatitis B and that people currently receiving telbivudine should have the option to continue therapy until they and their clinicians consider it appropriate to stop.

[Pharmacoeconomic evaluation of telbivudine vs. lamivudine in treating the patients with HBeAg-positive and negative chronic hepatitis B].

OBJECTIVE: To evaluate long-term cost effectiveness of telbivudine and lamivudine for the treatment of CHB. METHODS: Cost effectiveness was conducted from social health insurance perspective. A Markov model was established based on disease progression pattern and the data from the 2 years GLOBE clinical trial. The information of annual medical expenditure and quality-of-life assessment for different CHB-related diseases was obtained from literature. Incremental cost per life year or quality-adjusted life year gained was measured. RESULTS: Compared with lamivudine, the incremental cost for 1 additional QALY gained with telbivudine in treating HBeAg-positive and -negative CHB were 5403 yuan and 28239 yuan in Beijing, as well 4916 yuan and 29618 yuan in Guangzhou, respectively. According to national economic burden of CHB-related diseases, the ICER with telbivudine vs lamivudine were 1282 yuan and 31565 yuan for HBeAg-positive and -negative CHB. CONCLUSION: According to WHO recommendation for ICER threshold, telbivudine is cost effective in treating HBeAg-positive and -negative CHB, as compared to lamivudine.

On-treatment outcome prediction and adjustment during chronic hepatitis B therapy: now and future.

Studies published to date regarding on-treatment outcome prediction during chronic hepatitis B therapy were reviewed. Studies have shown that initial virological responses in terms of week 24 serum hepatitis B virus (HBV) DNA levels are associated with therapeutic outcomes of 1-year pegylated interferon-alpha and entecavir therapy, and weeks 52 or 104 of lamivudine and telbuvudine therapy. HBV DNA levels at week 48 are also associated with long-term adefovir therapy outcomes. Conceptual on-treatment adjustment and strategies have been proposed; however, this approach seems only necessary during therapy with nucleos(t)ide analogues with substantial risk of drug resistance. In addition, studies are needed to decide whether switching to or adding on a second drug, and with which drug, is the most cost-effective strategy.

Current status of nucleoside antivirals in chronic hepatitis B.

Chronic hepatitis B is a serious disease both worldwide and in the United States. There are two types of drugs available to treat chronic hepatitis B virus (HBV) infection: interferons that boost the immune system, and antiviral or nucleoside analogues that are designed to interfere with HBV DNA to prevent its replication. This review focuses on nucleoside antivirals, namely lamivudine, entecavir and telbivudine, which are widely prescribed for patients with the disease, particularly lamivudine. Additionally, current Food and Drug Administration-approved nucleoside antivirals for hepatitis B will be briefly highlighted. Comparisons are performed based on previous clinical trials from primary sources. Treatments with entecavir and telbivudine are compared with lamivudine treatment in regard to pharmacotherapy, resistance and cost-effectiveness. Outcomes varied depending on each trial, but the main findings were more favorable for entecavir and telbivudine treatments than for lamivudine treatment. It was concluded that entecavir treatment is associated with better outcomes than lamivudine in the three aspects studied. Similarly, telbivudine showed more improvements than lamivudine in all three areas. Concomitant pharmacotherapy, especially in lamivudine-refractory patients, demonstrated significant improvement in the management of chronic hepatitis B. Furthermore, the availability of hepatitis B vaccines should enable us to prevent the occurrence of the disease.

Telbivudine: a new treatment for chronic hepatitis B.

Three hundred and fifty million people worldwide are estimated to be chronically infected with hepatitis B virus. 15%-40% of these subjects will develop cirrhosis, liver failure or hepatocellular carcinoma during their life. The treatment of chronic hepatitis B has improved dramatically over the last decade merits to the advent of nucleoside/nucleotide analogues and the use of pegylated interferons. Approved drugs for chronic hepatitis B treatment include: standard interferon-alpha 2b, pegylated interferon-alpha 2a, lamivudine, adefovir dipivoxil, and entecavir. Unfortunately, these agents are not effective in all patients and are associated with distinct side effects. Interferons have numerous side effects and nucleoside or nucleotide analogues, which are well tolerated, need to be used for prolonged periods, even indefinitely. However, prolonged treatment with nucleoside or nucleotide analogues is associated with a high rate of resistance. Telbivudine is a novel, orally administered nucleoside analogue for use in the treatment of chronic hepatitis B. In contrast to other nucleoside analogues, Telbivudine has not been associated with inhibition of mammalian DNA polymerase with mitochondrial toxicity. Telbivudine has demonstrated potent activity against hepatitis B with a significantly higher rate of response and superior viral suppression compared with lamivudine, the standard treatment. Telbivudine has been generally well tolerated, with a low adverse effect profile, and at its effective dose, no dose-limiting toxicity has been observed. Telbivudine is one of the most potent antiviral agents for chronic hepatitis B virus and was approved by the FDA in late 2006.

Hyperlactataemia and lactic acidosis during antiretroviral therapy: relevance, reproducibility and possible risk factors.

OBJECTIVE: To evaluate the prevalence, outcome and possible risk factors for hyperlactataemia and lactic acidosis in HIV-positive persons receiving antiretroviral therapy. METHODS: Cross-sectional and longitudinal data from a prospectively collected clinical database. Associations with antiretroviral regimen, clinical and laboratory parameters were assessed using univariate and multivariate Cox's proportional hazards model. RESULTS: Patients naive to therapy and patients on current therapy for a minimum of 4 months were assessed. Median lactate was 1.1 mol/l in 253 untreated individuals and 1.4 mmol/l in 1239 patients stable on therapy for at least 4 months. At least two on-therapy samples were available for 750 of the 1239 individuals, taken a median 92 days apart. Lactate measurement showed a low positive predictive value of 38.9% but a high negative predictive value (98%) for normal values. Lactate was elevated > or = 2.4 mmol/l in 102 individuals on at least one occasion. In the multivariate Cox's proportional hazards model, no demographic characteristics were associated with hyperlactataemia. Didanosine-containing regimens doubled the relative hazard of hyperlactataemia compared with those sparing didanosine. Abacavir-containing regimens reduced the hazard of hyperlactataemia. Choice of thymidine analogue did not influence risk. Hyperlactataemia was associated with acid-base disturbance. Use of didanosine and female sex were over-represented amongst nine patients with severe hyperlactataemia (> 5 mmol/l) or lactic acidosis. CONCLUSIONS: Screening of lactate is of limited use in asymptomatic individuals on antiretroviral therapy. Raised lactate represents part of a spectrum of lactate and acid-base disturbance that infrequently includes lactic acidosis. Didanosine appears associated with an increased risk of hyperlactataemia.

The 2-(N-formyl-N-methyl)aminoethyl group as a potential phosphate/thiophosphate protecting group in solid-phase oligodeoxyribonucleotide synthesis.

[reaction in text] The 2-(N-formyl-N-methyl)aminoethyl deoxyribonucleoside phosphoramidite 1 has been synthesized and used in the solid-phase synthesis of an octadecathymidylic acid as a cost-efficient monomer for potential application in the preparation of therapeutic oligonucleotides. The 2-(N-formyl-N-methyl)aminoethyl group can be cleaved from oligonucleotides according to a unique thermolytic cyclodeesterification process at pH 7.0. In addition to being cost-effective, the use of 1 simplifies oligonucleotide postsynthesis processing by eliminating the utilization of concentrated ammonium hydroxide in oligonucleotide deprotection.

Assessment of DNA oxidative damage by quantification of thymidine glycol residues using gas chromatography/electron capture negative ionization mass spectrometry.

A technique to assess DNA oxidative damage by quantification of thymidine glycol residues is described. 2-Methylglycerate was released from thymidine glycol in DNA by alkaline cleavage/borodeuteride reduction, then derivatized to form a combined pentafluorobenzyl-tertbutyldimethylsilyl (PFB-TBDMS) derivative and analyzed by gas chromatography/electron capture negative ionization mass spectrometry. [2H4]Thymine glycol was used as an internal standard. The derivatization chemistry was assessed by using [14C-methyl]glycerate. Successful esterification was achieved with 75-80% yield using tetrabutylammonium sulfate-assisted anhydrous pentafluorobenzylation. The PFB-TBDMS derivative exhibits excellent chromatographic and detection properties with a detection limit of 41 amol injected on column. Freshly dissolved calf thymus DNA was used to test the method performance. The background level of thymidine glycol detected in this DNA was 11.7 +/- 0.3 x 10(-6) mol thymidine glycol per 1 mol thymidine. The thymidine glycol background in undamaged DNA establishes a lower limit of oxidative damage below which biological oxidation events would not be measured by this method. The method was linear for 4-20 micrograms DNA added per tube. The minimum measurable amount of thymidine glycol in DNA sample was 36 fmol. An increased level of thymidine glycol was measured in salmon sperm DNA which had autoxidized during storage in a refrigerated aqueous solution, 71.2 +/- 14.3 x 10(-6) mol thymidine glycol per 1 mol thymidine.

Assessment and management of the AIDS patient with neuropsychiatric disturbances.

The studies reviewed here and ongoing work indicate a primary role for psychiatry in treating patients with the acquired immunodeficiency syndrome (AIDS) and human immunodeficiency virus (HIV) infection. Those patients often have neuropsychiatric disorders concurrent with the complications of physical disease. It is important to understand the diagnostic criteria for patients with HIV-related disorders to distinguish CNS disturbances caused by infections from those psychiatric problems exacerbated by the social consequences of the syndrome. Although treatment is difficult in immunocompromised patients and treatments may cause serious side effects, many of the CNS symptoms of AIDS patients can be treated in the same way as other diseases of the CNS. Psychostimulants are the most promising therapeutic agents for AIDS patients. In the treatment of psychotic episodes, high-potency neuroleptics at low dosages have been used successfully. In all therapies, careful consideration must be given to possible adverse reactions, which may be more serious in HIV-related diseases.