Exploring the role of oxidative stress and the effect of N-acetylcysteine in thiopurine-induced liver injury in inflammatory bowel disease: A randomized crossover pilot study

Thiopurine treatment is regularly complicated by drug-induced liver injury. It has been suggested that oxidative stress may play a synergistic role. To assess whether thiopurine-induced liver injury coincides with increased oxidative stress and whether co-administration with N-acetylcysteine is protective, we performed a randomized open label crossover pilot study in inflammatory bowel disease patients with thiopurine-induced increased serum liver tests. The study comprised four stages of 4 weeks. Patients received no additional therapy followed by N-acetylcysteine 1200 mg twice a day, or the other way around, alongside ongoing thiopurine treatment. The third and fourth stages comprised a washout period and thiopurine reintroduction period. Nine patients completed the study, and the addition of N-acetylcysteine decreased myeloperoxidase concentrations (33.6-24.5 pmol/L, p = 0.038). The other biomarkers remained unchanged, including thiopurine metabolites, xanthine oxidase activity, thiopurine S-methyltransferase activity and serum liver enzyme activity tests. Reintroduction of thiopurines led to an increase of F2-isoprostanes (101-157 ng/mmol, p = 0.038), but not of serum liver enzyme activity tests. Results suggests that thiopurines may increase oxidative stress and although the addition of N-acetylcysteine led to a decrease in plasma myeloperoxidase concentrations, it does not protect from thiopurine-induced increase of serum liver tests.

Early proactive monitoring of DNA-thioguanine in patients with Crohn's disease predicts thiopurine-induced late leucopenia in NUDT15/TPMT normal metabolizers

BACKGROUND

Thiopurine-induced leucopenia significantly hinders the wide application of thiopurines. Dose optimization guided by nudix hydrolase 15 (NUDT15) has significantly reduced the early leucopenia rate, but there are no definitive biomarkers for late risk leucopenia prediction.

AIM

To determine the predictive value of early monitoring of DNA-thioguanine (DNATG) or 6-thioguanine nucleotides (6TGN) for late leucopenia under a NUDT15-guided thiopurine dosing strategy in patients with Crohn's disease (CD).

METHODS

Blood samples were collected within two months after thiopurine initiation for detection of metabolite concentrations. Late leucopenia was defined as a leukocyte count < 3.5 × 109/L over two months.

RESULTS

Of 148 patients studied, late leucopenia was observed in 15.6% (17/109) of NUDT15/thiopurine methyltransferase (TPMT) normal and 64.1% (25/39) of intermediate metabolizers. In patients suffering late leucopenia, early DNATG levels were significantly higher than in those who did not develop late leucopenia (P = 4.9 × 10-13). The DNATG threshold of 319.43 fmol/μg DNA could predict late leucopenia in the entire sample with an area under the curve (AUC) of 0.855 (sensitivity 83%, specificity 81%), and in NUDT15/TPMT normal metabolizers, the predictive performance of a threshold of 315.72 fmol/μg DNA was much more remarkable with an AUC of 0.902 (sensitivity 88%, specificity 85%). 6TGN had a relatively poor correlation with late leucopenia whether in the entire sample (P = 0.021) or NUDT15/TPMT normal or intermediate metabolizers (P = 0.018, P = 0.55, respectively).

CONCLUSION

Proactive therapeutic drug monitoring of DNATG could be an effective strategy to prevent late leucopenia in both NUDT15/TPMT normal and intermediate metabolizers with CD, especially the former.

Cholesteryl ester transfer protein inhibitors in the treatment of dyslipidemia: a systematic review and meta-analysis

Cholesteryl ester transfer protein (CETP) inhibitors are gaining substantial research interest for raising high density lipoprotein cholesterol levels. The aim of the research was to estimate the efficacy and safety of cholesteryl ester transfer protein inhibitors as novel lipid modifying drugs. Systematic searches of English literature for randomized controlled trials (RCT) were collected from MEDLINE, EBASE, CENTRAL and references listed in eligible studies. Two independent authors assessed the search results and only included the double-blind RCTs by using cholesteryl ester transfer protein inhibitors as exclusively or co-administrated with statin therapy irrespective of gender in enrolled adult subjects. Two independent authors extracted the data by using predefined data fields. Of 503 studies identified, 14 studies met the inclusion criteria, and 12 studies were included into the final meta-analysis. Our meta-analysis revealed that CETP inhibitors increased the HDL-c levels (n = 2826, p<0.00001, mean difference (MD) = 20.47, 95% CI [19.80 to 21.15]) and total cholesterol (n = 3423, p = 0.0002, MD = 3.57, 95%CI [1.69 to 5.44] to some extent combined with a reduction in triglyceride (n = 3739, p<0.00001, MD = -10.47, 95% CI [-11.91 to -9.03]) and LDL-c (n = 3159, p<0.00001, MD = -17.12, 95% CI [-18.87 to -15.36]) irrespective of mono-therapy or co-administration with statins. Subgroup analysis suggested that the lipid modifying effects varied according to the four currently available CETP inhibitors. CETP inhibitor therapy did not increase the adverse events when compared with control. However, we observed a slight increase in blood pressure (SBP, n = 2384, p<0.00001, MD = 2.73, 95% CI [2.14 to 3.31], DBP, n = 2384, p<0.00001, MD = 1.16, 95% CI [0.73 to 1.60]) after CETP inhibitor treatment, which were mainly ascribed to the torcetrapib treatment subgroup. CETP inhibitors therapy is associated with significant increase in HDL-c and decrease in triglyceride and LDL-c with satisfactory safety and tolerability in patients with dyslipidemia. However, the side-effect on blood pressure deserves more consideration in future studies.

Safety of CETP inhibition

PURPOSE OF REVIEW

Cholesteryl ester transfer protein (CETP)-inhibiting drugs effectively raise HDL cholesterol. In 2007, the CETP inhibitor torcetrapib unexpectedly showed increased fatality and cardiovascular events, possibly related to increased blood pressure and aldosterone levels caused by torcetrapib. Since then, novel CETP inhibiting drugs have been investigated. This review will discuss the safety of the CETP-inhibiting drugs.

RECENT FINDINGS

The novel CETP inhibitors dalcetrapib, evacetrapib and anacetrapib did not show harmful effects on blood pressure or aldosterone levels. Ultrasound brachial artery flow-mediated vasodilation, carotid MRI and (18)F-fluordeoxyglucose PET imaging studies, showed that dalcetrapib therapy had neither harmful nor beneficial effects on endothelial function, atherosclerosis progression, or vessel wall inflammation. Recently, the clinical endpoint study investigating dalcetrapib was announced to be terminated early, after the second interim analysis showed that dalcetrapib lacked clinically meaningful efficacy.

SUMMARY

Dalcetrapib, evacetrapib and anacetrapib did not show the harmful effects on aldosterone and blood pressure that were exhibited by torcetrapib, indicating that CETP inhibition is well tolerated. So far CETP inhibition did not show beneficial effects on clinical outcome. The phase III study with anacetrapib will give final answers on whether CETP inhibition can reduce cardiovascular events.

Effects of dalcetrapib in patients with a recent acute coronary syndrome

BACKGROUND

In observational analyses, higher levels of high-density lipoprotein (HDL) cholesterol have been associated with a lower risk of coronary heart disease events. However, whether raising HDL cholesterol levels therapeutically reduces cardiovascular risk remains uncertain. Inhibition of cholesteryl ester transfer protein (CETP) raises HDL cholesterol levels and might therefore improve cardiovascular outcomes.

METHODS

We randomly assigned 15,871 patients who had had a recent acute coronary syndrome to receive the CETP inhibitor dalcetrapib, at a dose of 600 mg daily, or placebo, in addition to the best available evidence-based care. The primary efficacy end point was a composite of death from coronary heart disease, nonfatal myocardial infarction, ischemic stroke, unstable angina, or cardiac arrest with resuscitation.

RESULTS

At the time of randomization, the mean HDL cholesterol level was 42 mg per deciliter (1.1 mmol per liter), and the mean low-density lipoprotein (LDL) cholesterol level was 76 mg per deciliter (2.0 mmol per liter). Over the course of the trial, HDL cholesterol levels increased from baseline by 4 to 11% in the placebo group and by 31 to 40% in the dalcetrapib group. Dalcetrapib had a minimal effect on LDL cholesterol levels. Patients were followed for a median of 31 months. At a prespecified interim analysis that included 1135 primary end-point events (71% of the projected total number), the independent data and safety monitoring board recommended termination of the trial for futility. As compared with placebo, dalcetrapib did not alter the risk of the primary end point (cumulative event rate, 8.0% and 8.3%, respectively; hazard ratio with dalcetrapib, 1.04; 95% confidence interval, 0.93 to 1.16; P=0.52) and did not have a significant effect on any component of the primary end point or total mortality. The median C-reactive protein level was 0.2 mg per liter higher and the mean systolic blood pressure was 0.6 mm Hg higher with dalcetrapib as compared with placebo (P<0.001 for both comparisons).

CONCLUSIONS

In patients who had had a recent acute coronary syndrome, dalcetrapib increased HDL cholesterol levels but did not reduce the risk of recurrent cardiovascular events. (Funded by F. Hoffmann-La Roche; dal-OUTCOMES ClinicalTrials.gov number, NCT00658515.).

Efficacy and safety of dalcetrapib in type 2 diabetes mellitus and/or metabolic syndrome patients, at high cardiovascular disease risk

AIMS

Mixed dyslipidaemia, characterized by low levels of high-density lipoprotein cholesterol (HDL-C) and high levels of triglycerides, is common in patients with type 2 diabetes mellitus (T2DM) and/or metabolic syndrome. Dalcetrapib effectively increases HDL-C levels by modulating cholesteryl ester transfer protein (CETP) activity. The aim of this analysis was to investigate the lipid modifying efficacy and safety of dalcetrapib in patients with T2DM and/or metabolic syndrome.

METHODS

Post hoc analysis of dalcetrapib therapy in five placebo-controlled, Phase II trials (4-48 weeks of duration) involving T2DM and/or metabolic syndrome, in dyslipidaemic patients with coronary heart disease (CHD) or CHD risk equivalent.

RESULTS

Both in patients with and without T2DM and/or metabolic syndrome, dalcetrapib decreased CETP activity by 26-58% and increased HDL-C levels by 23-34%, depending on dose and duration of treatment. Dalcetrapib did not significantly affect low-density lipoprotein cholesterol (LDL-C) or apolipoprotein B levels. Treatment with dalcetrapib was generally well tolerated with a similar number of adverse events reported between patient groups and between those receiving dalcetrapib compared with placebo.

CONCLUSIONS

Dalcetrapib similarly decreased CETP activity and increased HDL-C levels in patients with and without T2DM or metabolic syndrome; the ongoing Phase III dal-OUTCOMES study will help to determine if dalcetrapib's improvement in lipid levels also reduces cardiovascular morbidity and mortality.

Cholesteryl ester transfer protein inhibition to reduce cardiovascular risk: Where are we now?

Elevated low-density lipoprotein-cholesterol (LDL-C) and reduced high-density lipoprotein-cholesterol (HDL-C) are major risk factors for the development of cardiovascular disease. One approach to raising HDL-C is to inhibit the cholesteryl ester transfer protein (CETP), a plasma protein that promotes transfer of cholesteryl esters from HDL and other lipoprotein fractions. Drugs that inhibit CETP increase HDL-C and some lower LDL-C. However, the development of torcetrapib, the first CETP inhibitor to be tested in a human clinical outcomes trial, was terminated because it caused an excess of deaths and cardiovascular events. There is evidence, however, that torcetrapib had adverse off-target effects unrelated to CETP inhibition. This has opened the way for retesting of the hypothesis that CETP inhibitors will be anti-atherogenic in studies conducted with agents such as dalcetrapib and anacetrapib that do not share the off-target effects of torcetrapib. Clinical outcome trials with dalcetrapib and anacetrapib are currently under way.

Rationale and design of dal-VESSEL: a study to assess the safety and efficacy of dalcetrapib on endothelial function using brachial artery flow-mediated vasodilatation

OBJECTIVE

Dalcetrapib increases high-density lipoprotein cholesterol (HDL-C) levels through effects on cholesteryl ester transfer protein (CETP). As part of the dalcetrapib dal-HEART clinical trial programme, the efficacy and safety of dalcetrapib is assessed in coronary heart disease (CHD) patients in the dal-VESSEL study (ClinicalTrials.gov identifier: NCT00655538), the design and methods of which are presented here. RESEARCH DESIGN AND STUDY METHOD: Men and women with CHD or CHD risk equivalent, with HDL-C levels <50  mg/dL were recruited for a 36-week, double-blinded, placebo-controlled trial. After a pre-randomisation phase of up to 8 weeks, patients received dalcetrapib 600  mg/day or placebo in addition to their existing treatments. Brachial flow-mediated dilatation (FMD) measured by B-mode ultrasound represents endothelial function and is a validated marker for early atherosclerosis and cardiovascular disease risk.

MAIN OUTCOME MEASURES

The primary efficacy outcome is change from baseline in brachial FMD after 12 weeks. The primary safety endpoint is 24-hour ambulatory blood pressure monitoring (ABPM) assessed at week 4. Secondary endpoints include brachial FMD at 36 weeks, ABPM at 12 and 36 weeks, lipid profile, CETP mass and activity, and markers of inflammation, oxidation, and cardiovascular risk. Clinical endpoints are assessed as a composite endpoint for the dal-HEART Program.

CURRENT STATUS

In 19 European clinical centres, 476 subjects met inclusion criteria and have entered the study. In conclusion, the dal-VESSEL study is the largest multicentre trial with brachial FMD ever performed. The study assesses efficacy and safety of dalcetrapib on endothelial function, blood pressure, lipids, and clinical outcomes in CHD patients with below average HDL-C and will therefore provide vital information regarding its potential role in the preventative treatment of CHD risk.

Soccer shin guard reactions: allergic and irritant reactions

In spite of the worldwide popularity of soccer among youth and the common requirement of the use of protective shin guards, reports of allergy to shin guards is sparse. This is surprising in light of the fact that this equipment is often made of materials that are reported to cause allergies, and that friction and moisture from the use of these shin guards during the sport would seem to predispose soccer players to the development of an allergic response. We present eight patients that presented for evaluation of dermatitis under their shin guards--some of which had allergy to their shin guards and some of which were diagnosed as having an irritant reaction.

Rationale and design of the dal-OUTCOMES trial: efficacy and safety of dalcetrapib in patients with recent acute coronary syndrome

BACKGROUND

Despite contemporary therapies for acute coronary syndrome (ACS), morbidity and mortality remain high. Low levels of high-density lipoprotein (HDL) cholesterol are common among patients with ACS and may contribute to ongoing risk. Strategies that raise levels of HDL cholesterol, such as inhibition of cholesterol ester transfer protein (CETP), might reduce risk after ACS. Dal-OUTCOMES is a multicenter, randomized, double-blind, placebo-controlled trial designed to test the hypothesis that CETP inhibition with dalcetrapib reduces cardiovascular morbidity and mortality in patients with recent ACS.

DESIGN

The study will randomize approximately 15,600 patients to receive daily doses of dalcetrapib 600 mg or matching placebo, beginning 4 to 12 weeks after an index ACS event. There are no prespecified boundaries for HDL cholesterol levels at entry. Other elements of care, including management of low-density lipoprotein cholesterol, are to follow best evidence-based practice. The primary efficacy measure is time to first occurrence of coronary heart disease death, nonfatal acute myocardial infarction, unstable angina requiring hospital admission, resuscitated cardiac arrest, or atherothrombotic stroke. The trial will continue until 1,600 primary end point events have occurred, all evaluable subjects have been followed for at least 2 years, and 80% of evaluable subjects have been followed for at least 2.5 years.

SUMMARY

Dal-OUTCOMES will determine whether CETP inhibition with dalcetrapib, added to current evidence-based care, reduces cardiovascular morbidity and mortality after ACS.

The role of CETP inhibition in dyslipidemia

Cholesteryl ester transfer protein (CETP) inhibitors are currently being investigated because of their ability to increase high-density lipoprotein cholesterol levels. In various metabolic settings, the relationship between CETP and lipoprotein metabolism is complex and may depend largely on the concentration of triglyceride-rich lipoproteins. Two CETP inhibitors, JTT-705 and torcetrapib, are in an advanced phase of development. Following hopeful intermediate results, a large endpoint study using torcetrapib has just been discontinued due to increased mortality in torcetrapib-treated subjects. In this review we summarize clinical data on the use of CETP inhibitors.

Microfluidic platform for single nucleotide polymorphism genotyping of the thiopurine S-methyltransferase gene to evaluate risk for adverse drug events

Prospective clinical pharmacogenetic testing of the thiopurine S-methyltransferase gene remains to be realized despite the large body of evidence demonstrating clinical benefit for the patient and cost effectiveness for health care systems. We describe an entirely microchip-based method to genotype for common single nucleotide polymorphisms in the thiopurine S-methyltransferase gene that lead to serious adverse drug reactions for patients undergoing thiopurine therapy. Restriction fragment length polymorphism and allele-specific polymerase chain reaction have been adapted to a microfluidic chip-based polymerase chain reaction and capillary electrophoresis platform to genotype the common *2, *3A, and *3C functional alleles. In total, 80 patients being treated with thiopurines were genotyped, with 100% concordance between microchip and conventional methods. This is the first report of single nucleotide polymorphism detection using portable instrumentation and represents a significant step toward miniaturized for personalized treatment and automated point-of-care testing.

Dose escalating safety study of CNS 5161 HCl, a new neuronal glutamate receptor antagonist (NMDA) for the treatment of neuropathic pain

AIMS

The purpose of the current study was to establish the safety and maximal tolerated dose of CNS 5161 HCl.

METHODS

Forty patients with chronic neuropathic pain (23 male, 17 female) were treated with escalating dosages of CNS 5161. All adverse events to study drug, blood pressure, heart rate, ECG, drug level and clinical laboratory values were monitored. Actual pain was measured on a 100-mm visual analogue scale (VAS) and ordinal verbal pain scores.

RESULTS

The most commonly occurring nervous system disorder was headache, which was found more often during placebo than during CNS 5161 HCl treatment. Visual disturbances were experienced by 16.7% of patients receiving 250 microg and by 33.3% receiving 500 microg CNS 5161 HCl, but not during placebo treatment. An increase in blood pressure was observed in 8.3% of patients receiving 250 microg and in 50% of patients receiving 500 microg CNS 5161 HCl, compared with 15.4% during placebo treatment. The study was abandoned after two patients entered the 750 microg cohort due to a sustained systolic blood pressure response. Although this study was underpowered for the confirmation of efficacy, some indications of greater pain relief after 500 microg CNS 5161 compared with placebo could be observed (change in VAS between baseline and 12 h 10 +/- 22 mm vs. 2 +/- 19 mm; P = 0.11).

CONCLUSIONS

CNS 5161 HCl was reasonably well tolerated up to 500 microg. The most common adverse events were hypertension, headache and mild visual disorders.

Allergic contact dermatitis from mercapto compounds

Despite being well-known allergens, mercaptobenzothiazole and its derivatives continue to be widely used in natural and synthetic rubber, in the mining industry, and in a variety of nonrubber products. The purpose of this article is to review the epidemiology and the clinical characteristics of allergic contact dermatitis from mercapto compounds.

The central nervous system effects, pharmacokinetics and safety of the NAALADase-inhibitor GPI 5693

AIM

The aim was to assess the central nervous system (CNS) effects, pharmacokinetics and safety of GPI 5693, an inhibitor of a novel CNS-drug target, NAALADase which is being evaluated for the treatment of neuropathic pain.

METHODS

This was a double-blind, placebo-controlled, exploratory study in healthy subjects receiving oral GPI 5693 single ascending doses of 100, 300, 750, 1125 mg with a placebo treatment randomly interspersed. An open-label, parallel extension examined the effects of food and sex on the pharmacokinetics of 750, 1125 and 1500 mg doses. Blood samples were collected for pharmacokinetic and biochemical/haematological safety analysis, vital signs, ECG and adverse event checks were performed regularly up to 48 h postdose. Postdose CNS effects were assessed using eye movements, adaptive tracking, electroencephalography (EEG), body sway and Visual Analogue Scales (VAS).

RESULTS

CNS effects were mainly observed after the 1125 mg dose, showing a significant decrease of adaptive tracking performance, VAS alertness and VAS mood, and an increase of EEG occipital alpha and theta power. Gastro-intestinal (GI) adverse effects were frequent at higher doses. No clinically significant changes in vital signs or ECG were noted during any of the treatments. The therapeutically relevant concentration range (950-11 100 ng ml(-1)) as determined from animal experiments was already reached after the 300 mg dose. C(max) after the 300 mg and 750 mg dose was 2868 and 9266 ng ml(-1) with a t(1/2) of 2.54 and 4.78 h, respectively. Concomitant food intake (with the 750 mg and 1125 mg doses) reduced C(max) by approximately 66% and AUC by approximately 40%. With concomitant food intake, the dose-normalized C(max) also decreased significantly by -5.6 (CI: -2.6 to -8.7) ng ml(-1) mg(-1). The pharmacokinetic variability was largest after the 300 mg and 750 mg dose, resulting in a SD of approximately 50% of the C(max).

CONCLUSION

NAALADase inhibition with GPI 5693 was safe and tolerable in healthy subjects. Plasma concentrations that were effective in the reversal of hyperalgesia in the chronic constrictive injury animal model of neuropathic pain were obtained at doses of 300, 750 and 1125 mg in the fasted state. Comcomitant food intake reduced C(max) and AUC. CNS effects and GI AEs increased in incidence over placebo only at the 1125 mg dose.

Miscellaneous hydrocarbon solvents

The solvents discussed in this article are common solvents not categorized as halogenated, aromatic, or botanical. The solvents discussed are categorized into two groups: hydrocarbon mixtures and single agents. The hydrocarbon mixtures discussed are Stoddard solvent, naphtha, and kerosene. The remaining solvents described are n-hexane, methyl n-butyl ketone, dimethylformamide, dimethyl sulfoxide, and butyl mercaptans. Effects common to this group of agents and their unique effects are characterized. Treatment of exposures and toxic effects of these solvents is described, and physiochemical properties and occupational exposure levels are listed.

Dietary alkyl thiol free radicals (RSS) can be as toxic as reactive oxygen species (ROS)

Harmful free-radicals, such as superoxide anion (a reactive oxygen species: ROS) are produced during aerobic respiration in all tissues because of only partial reduction of some oxygen molecules in mitochondria: this is due to one-electron reduction of each atom of oxygen, instead of four-electron reduction per molecule of oxygen to form water. Similarly, in liver, and many other tissues such as lung and brain, an electron transfer chain from NADPH to water occurs (with insertion of one oxygen atom into xenobiotic substrates) that uses cytochromes P450 (EC 1.14.14.1) as the electron acceptor. Here, futile recycling of electrons, in the absence of substrate produces the superoxide anion (*O2')--see above. Reactive oxygen species (ROS) and reactive sulfur species (RSS) may act in unison to damage biomolecules. For example, damage to biomolecules can occur by attack on phospholipid membranes, and also the targeting of DNA results in mutagenicity and associated carcinogenicity-related mutagenic damage. Free radical injury to low density lipoprotein (LDL) has been identified in the causation of atherosclerosis implicated in arterial disease, which can lead to heart attack and strokes.

Long-term effects of a novel phosphorothionate (RPR-II) on detoxifying enzymes in brain, lung, and kidney rats

The effects of a phosphorothionate, 2-butenoic acid-3-(diethoxyphosphinothioyl) methyl ester (RPR-II), on the activities of glutathione S-transferase (GST) and UDP-glucuronyltransferase (UDPGT) and the level of glutathione (GSH) were evaluated in rats after administration of RPR-II at 0.014 (low), 0.028 (medium), and 0.042 (high) mgkg(-1)day(-1) for 90 days and also at 28 days (withdrawal) after stopping treatment. Brain GST activity and GSH level decreased significantly at the high dose on the 45th and 90th days of treatment. Dose- and time-dependent decreases in GST activity and GSH was level were observed in lung at medium and high doses and in kidneys at all three doses on both the 45th and 90th days. UDPGT activity increased significantly in kidneys at the medium and high doses at 45 and 90 days. Brain and lung did not display any significant variations in UDPGT activity when compared with the control. Interestingly, the withdrawal study revealed that the effect was reversible within 28 days of cessation of treatment, when enzyme activity reverted to levels close to those of controls. The study revealed that RPR-II affected the GSH- and GST-dependent detoxification system of the treated tissues of rat and its potential to modulate the enzymes is in the order kidneys>lung>>brain. The present subacute study suggests that RPR-II may bring about physiological upsets by altering GSH- and GST-dependent events in different tissues of exposed organisms.

Efficacy and safety of a novel cholesteryl ester transfer protein inhibitor, JTT-705, in humans: a randomized phase II dose-response study

BACKGROUND

Cholesteryl ester transfer protein (CETP) mediates the transfer of neutral lipids between lipoproteins. High plasma levels of CETP are correlated with low HDL cholesterol levels, a strong risk factor for coronary artery disease. In earlier studies, JTT-705, a novel CETP inhibitor, was shown to increase plasma HDL cholesterol and to inhibit the progression of atherosclerosis in cholesterol-fed rabbits. This study describes the first results using this CETP inhibitor in humans.

METHODS AND RESULTS

In a randomized, double-blind, and placebo-controlled trial, we evaluated the efficacy and safety of daily treatment with 300, 600, and 900 mg JTT-705 in 198 healthy subjects with mild hyperlipidemia. Treatment with 900 mg JTT-705 for 4 weeks led to a 37% decrease in CETP activity (P<0.0001), a 34% increase in HDL cholesterol (P<0.0001), and a 7% decrease in LDL cholesterol (P=0.017), whereas levels of triglycerides, phospholipid transfer protein, and lecithin-cholesterol acyltransferase were unaffected. In line with the increase of total HDL, a rise of HDL2, HDL3, and apolipoprotein A-I was also noted. JTT-705 showed no toxicity with regard to physical examination and routine laboratory tests.

CONCLUSIONS

We show that the use of the CETP inhibitor JTT-705 in humans is an effective means to raise HDL cholesterol levels with minor gastrointestinal side effects (P=0.06). Although these results hold promise, further studies are needed to investigate whether the observed increase in HDL cholesterol translates into a concomitant reduction in coronary artery disease risk.

Similarity between eruptions induced by sulfhydryl drugs and acute cutaneous graft-versus-host disease after bone marrow transplantation

Cutaneous GVHD is histologically similar to eruptions induced by drugs containing a sulfhydryl group. The levels of interleukin-2 and interleukin-2 receptor were determined in a group of patients undergoing bone marrow transplantation (BMT) without graft-versus-host disease or any other complications and in a group with cutaneous graft-versus-host disease (GVHD) alone. In patients who only developed cutaneous GVHD, both interleukin-2 and inter-leukin-2 receptor levels were elevated when the disease was evident. As the elevation of these parameters became more marked, the grade of cutaneous graft versus-host disease also increased. In some patients, only one of the two parameters was elevated and the grade of graft-versus-host disease was low or no skin manifestations were seen. These findings suggest that interleukin-2 and interleukin-2 receptor act together in the development of cutaneous GVHD. This study also showed that the mechanism of cutaneous GVHD resembles that involved in the induction of eruptions by sulfhydryl-containing drugs.

Radioprotection by antioxidants

The role of reactive oxygen species in ionizing radiation injury and the potential of antioxidants to reduce these deleterious effects have been studied in animal models for more than 50 years. This review focuses on the radioprotective efficacy and the toxicity in mice of phosphorothioates such as WR-2721 and WR-151327, other thiols, and examples of radioprotective antioxidants from other classes of agents. Naturally occurring antioxidants, such as vitamin E and selenium, are less effective radioprotectors than synthetic thiols but may provide a longer window of protection against lethality and other effects of low dose, low-dose rate exposures. Many natural antioxidants have antimutagenic properties that need further examination with respect to long-term radiation effects. Modulation of endogenous antioxidants, such as superoxide dismutase, may be useful in specific radiotherapy protocols. Other drugs, such as nimodipine, propranolol, and methylxanthines, have antioxidant properties in addition to their primary pharmacological activity and may have utility as radioprotectors when administered alone or in combination with phosphorothioates.

Mortalities of workers at the Nitro plant with exposure to 2-mercaptobenzothialzole

OBJECTIVES

An update of a study of workers exposed to 2-mercaptobenzothiazole (MBT) at a rubber chemicals plant in Nitro, West Virginia is reported. The earlier study found high rates of lung cancer, prostate cancer, and bladder cancer in these workers who also had potential exposure to 4-aminobiphenyl (PAB), a potent bladder carcinogen.

METHODS

This cohort mortality study examines the mortalities of 1059 full time white male production workers employed at the plant from 1955 to 1977. A detailed exposure assessment was done on the 600 workers with exposure to MBT. Nine years of additional follow up to the previous study are added.

RESULTS

It was found that MBT workers have expected rates of lung (standardised mortality ratio (SMR) = 1.0 95% confidence interval (95% CI) 0.7 to 1.5) and prostate (SMR = 0.9, 95% CI 0.2 to 2.3) cancer. There was an excess of bladder cancer among MBT workers who had definite exposure to PAB (SMR = 27.1, 95% CI 11.7 to 53.4), and MBT workers with potential exposure to PAB (SMR = 4.3, 95% CI 1.4 to 10.0). However, there were no deaths from bladder cancer among workers with no exposure to PAB (SMR = 0.0, 95% CI 0.0 to 24.7), although there were only 0.2 deaths expected.

CONCLUSIONS

The potential confounding of exposure to an unknown portion of PAB in the MBT workers makes it impossible to evaluate risk of bladder cancer in this population at this time. However, exposure to MBT does not seem to increase the risk of most cancers including cancers of the lung and prostate.

Active oxygen species generation and cellular damage by additives of parenteral preparations: selenium and sulfhydryl compounds

We investigated the relationship between active oxygen species (AOS) generation and cultured vascular endothelial cellular damage caused by simultaneous exposure to selenium compounds and sulfhydryl compounds such as cysteine (Cys) or reduced glutathione (GSH). Selenium compounds, selenite, selenate or selenomethionine (SeMet), are added to total parenteral nutrition (TPN) and intravenously administered. We confirmed by luminol dependent chemiluminescence, an indicator of AOS generation, that selenite generates AOS in the presence of clinical concentrations of sulfhydryl compounds, 0.5 mM Cys or 0.5 mM GSH, and that the amount of AOS generated reaches the maximum when their mole ratio is 1:50. However, AOS generation was not observed after simultaneous administration of various concentrations of selenate or SeMet with sulfhydryl compounds. Moreover, simultaneous exposure to 10 microM selenite and sulfhydryl compounds was found to result in significant increases in the [3H]-adenine and lactate dehydrogenase (LDH) release rates from cells, a significant decrease in the amount of cellular protein, and enhancement of cellular damage as compared with after exposure to selenite alone. However, simultaneous exposure to 10 microM selenate or 10 microM SeMet together with sulfhydryl compounds did not induce cellular damage. These findings revealed that selenite generates AOS and causes cellular damage in the presence of sulfhydryl compounds. Accordingly, it seems better to choose selenate or SeMet instead of selenite when a selenium compound is to be added to TPN.

Influence of odour immissions from cellulose-paper industry on some health indicators

The population of the town of Stamboliisky, Bulgaria, is constantly exposed to air pollution which includes immissions of unpleasant odours like methylmercaptane, dimethylsulphide, hydrogen sulfide, etc. Most of these can cause serious olfactory damage even at concentrations well below the toxic levels. The aim of the present study was to analyse the effect of odour immissions on the health status of the people in the town of Stamboliisky.

Thimerosal positivities: patch testing to methylmercury chloride in subjects sensitive to ethylmercury chloride

The aim of this paper was to evaluate whether methylmercury chloride (MeHgCl) aq., when patch tested in a group of thimerosal-positive subjects reacting to ethylmercury chloride (EtHgCl), might be a reliable model for the better understanding of interactions between alkylmercury compounds and the skin. 19 out of 21 consecutive patients who previously had given positive patch-test reactions to both ethylmercury chloride 0.0165% eth.(EtHgCl, 0.615 mM) and MeHgCl 0.031% aq.(1.23 mM), and negative reactions to thiosalicylic acid 0.05% (3.24 mM) aq./eth. 50/50, were repatch tested to 8 microl of MeHgCl 0.031% aq. and to 8 microl of aq. solutions containing MeHgCl mixed with cysteine, glutathione, ZnSO4, MgSO4, MnSO4, ZnCl2, MgCl2 and MnCl2, respectively. The results showed that cysteine, glutathione and Zn(II) salts were able to abolish the positive reactions, demonstrating the rôle played by both thiol groups and Zn(II) itself. Patch tests concomitantly carried out in 16 out of 19 patients to 8 microl of aqueous MeHgCl and to 8 microl of aqueous solutions containing MeHgCl and MeHgCl mixed to fragment 56-61 of metallothionein I (MT I), MT I and MT II-Zn, respectively, revealed that all the MTs tested were able to reduce or to inhibit the reactions, demonstrating the effect of the thiol groups. Due to the close chemical similarities to EtHgCl and to its water solubility, MeHgCl seems to be a suitable model for evaluating the reactivity of alkylmercury compounds in the skin. We speculate that both EtHg- and MeHg-derivatives are xenobiotics with similar reactivity. However, the lack of clinical relevance of the reactions to both alkyl compounds lead us to conclude that, since environmental exposure does not seem to play a pivotal rôle, they probably have mostly to do with compounds included in in the standard series, and are elicited by reduced function of physiological SH chelators.

Diet and pemphigus. In pursuit of exogenous factors in pemphigus and fogo selvagem

Individuals with a genetic predisposition to pemphigus will develop the disease only when one or more additional factors are present. The nature of these factors is as yet unknown, but our starting point was that certain drugs (penicillamine, captopril, and rifampicin) are recognized as such factors. Since some nutrients have chemical compositions similar to these known causative drugs, these nutrients may act similarly and, therefore, nutritional factors should also be suspected. As when drugs are involved, elimination of the inciting ingredients may be crucial for management of the disease. This article discusses the possible role of nutritional ingredients in the disease process of pemphigus, including fruit, leaves, roots, seeds, and even water. Possible causative candidates are thiol, thiocyanate, phenols, and tannins.

Thimerosal positivities: the rôle of SH groups and divalent ions

For a better understanding of the mechanistic details of the interactions of organomercury compounds inside the skin, 32 subjects who previously had given positive patch-test reactions to thimerosal (TH) and negative reactions to thiosalicylic acid, were divided into 2 groups. 16 subjects were repatch tested to ethylmercury chloride (EtHgCl) and to solutions containing EtHgCl mixed with L-cysteine and glutathione, respectively. The remaining 16 were repatch tested to EtHgCl and to solutions containing EtHgCl mixed with chlorides of Zn, Mg, and Mn, respectively. The results showed that whilst L-cysteine, glutathione and ZnCl2 were able to abolish or to reduce the positive reactions to EtHgCl, chlorides of Mg and Mn were unable to do so. Patch tests revealed that in causing positive reactions to TH, EtHg probably interacted with thiol groups and with Zn ions, as in biological systems when causing toxic effects. The limited number of TH reactions in the general population, the constant presence of concomitant positive reactions to EtHgCl and MeHgCl, and the lack of cross-reactivity with other organic or inorganic mercury compounds, lead us to speculate that reactions to TH are due to organomercury alkyl compounds, and that positive subjects have a constitutively reduced capability to metabolize organomercury compounds, rather than to reveal previous exposure.

Disposition and tissue distribution of boron after infusion of borocaptate sodium in patients with malignant brain tumors

PURPOSE

In the frame of the Czech boron neutron capture therapy (BNCT) project, a clinical Phase I study of borocaptate sodium [Na2B12H11SH (BSH)] as the boron-10 delivery agent was performed to obtain data on disposition and tissue distribution of boron after an infusion of this compound, as well as to establish an optimal protocol for BNCT of malignant cerebral tumors.

METHODS AND MATERIALS

The kinetics of boron disposition after an infusion of borocaptate sodium (25 mg/kg body wt over the period of 1 h) was studied in a group of 10 patients with astrocytoma or glioblastoma of cerebral hemispheres using a modification of the Soloway-Messer colorimetric method. The boron content of tissues (tumor, healthy brain, dura mater, muscle, skin, and cranial bone) removed during the operation performed with latencies varying between 3 and 18 h was investigated by atomic emission spectrometry.

RESULTS

Compartmental analysis of boron blood concentrations has shown that in the majority of patients (four males and three females), the concentration decline can be adequately described by a two-compartment pharmacokinetic model (i.e., by a biexponential relationship). The calculated half-lives of the initial (fast) phase of the concentration decline varied between 0.85 and 3.65 h, whereas the half-life values for the terminal (slow) phase ranged between 22.2 and 111.8 h. However, in the remaining three patients (all females), the goodness of fit of the boron concentration data was significantly better when a pharmacokinetic model with three compartments was assumed. In these patients, therefore, an additional ultrafast phase with a half-life varying between 17 and 37 min was detected in the beginning of the boron blood concentration decline. On the other hand, in one of these patients, the half-life of the terminal phase was found to be 415 h (i.e., more than 17 days). Such a long persistence in the body is explained by the very high value of the total distribution volume, indicating extensive binding of BSH in peripheral tissues. Another reason may be enterohepatic recycling of BSH.

CONCLUSION

Tumor-to-blood ratios higher than 1.5, which are necessary for an effective outcome of BNCT, can be obtained only if the time interval elapsing between the onset of surgery and termination of BSH infusion is at least 12 h.

The diuretic effect of borocaptate sodium in rats and in patients with brain tumors

Kidney function changes after single-dose administration of borocaptate sodium were studied in rats and in patients with brain tumors. Changes of glomerular filtration rate (GFR) measured as 14C-inulin clearance and urine flow rate (UFR) after a slow intravenous injection of BSH (25 and 50 mg/kg b.w., respectively) were investigated in rats under pentobarbital anesthesia. The effect of BSH has been compared with that of its disulfide (BSSB) which is spontaneously generated by oxidation of BSH during storage. It was found that BSH decreases GFR in relation to dose and, in the same way, causes a temporary increase of UFR. On the other hand, BSSB (50 mg/kg) induced a large reversible decrease of GFR as well as a decrease of urine excretion. Measurements of GFR (inulin clearance), renal plasma flow (PAH clearance) and urine excretion were taken in a group of patients with brain tumors in which boron disposition after an infusion of BSH (25 mg/kg b.w. over 1 h) had been studied. An increase in urine production was the dominant effect (up to 200% of the initial value), with the alterations of GFR and RPF being of minor significance except in one patient with a GFR reduction up to almost 50% the original value. Kidney function changes after BSH or BSSB administration are supposedly related to the high retention of BSH in kidney.

Evaluation of dithiol chelating agents as potential adjuvants for anti-IL-2 receptor lead or bismuth alpha radioimmunotherapy

The dithiol chelating agents 2,3-dimercapto-1-propanesulfonic acid (DMPS) and meso-2,3-dimercaptosuccinic acid (DMSA) were evaluated for use as potential adjuvants to reduce or prevent radiotoxicity in anti-interleukin-2 receptor (IL-2R) Lead-212 or Bismuth-212 alpha-radioimmunotherapy. DMPS was less toxic than DMSA to tumor cell lines in culture. No adverse effects on the ability of an anti-IL-2R monoclonal antibody (MAb) to bind to its specific antigen were detected using DMPS or DMSA at concentrations up to 600 ug/mL in 10% or 100% mouse serum. After a 5-day oral administration of chelating agent, neither acute nor chronic toxicities on blood hematology, blood chemistry or organ weights were observed for treated mice. DMPS and DMSA were effective in accelerating whole body clearance of the gamma-emitting tracer Bismuth-206. Both chelates significantly reduced femur uptake of tracer when compared to nontreated control mice. However, only DMPS prevented early (2 h postinjection) renal accumulation. These studies support the use of DMPS as a potential adjuvant chelation therapy in Lead-212 or Bismuth-212 radioimmunotherapy protocols.

Are acantholysis and transglutaminase inhibition related phenomena?

BACKGROUND

The loss of intercellular cohesion among keratinocytes (acantholysis) may be considered the histologic marker of pemphigus. Many drugs, especially thiol drugs, proved to be able to provoke in vitro acantholysis by biochemical mechanisms interfering with the disulfide and thiol group balance. As to nonthiol drugs, the pathomechanism of acantholysis is still unexplained.

OBJECTIVE

To explain the molecular mechanism of enalapril-induced acantholysis a potential link between transglutaminase (TGase) activity and the effects of this drug was investigated.

METHODS

TGase activity in extracts from human breast skin cultured in the presence of thiopronine, captopril and enalapril were evaluated in vitro. The acantholytic potential of cystamine, a known TGase inhibitor, was also investigated.

RESULTS

Enalapril, the most powerful acantholytic drug in vitro, was found to inhibit both the purified enzyme and the TGase activity in the extracts from cultured human breast skin explants. Kinetic studies showed that enalapril inhibition was competitive with respect to the amino acceptor substrate and uncompetitive with respect to the amino donor substrate. Moreover, an acantholytic effect of cystamine on explants of normal human skin was shown.

CONCLUSIONS

These results suggest that acantholysis and the inhibition of TGase activity could be two related phenomena.

Identical HLA class II alleles predispose to drug-triggered and idiopathic pemphigus vulgaris

In pemphigus vulgaris, a dermatological autoimmune disease, specific human leukocyte antigen (HLA) class II alleles, DR4 (DRB1*0402) and DRw14 (DRB1*1401, in linkage disequilibrium with DQB1*0503), are thought to be susceptibility genes involved in the onset of the disease. We studied the HLA class II alleles (DQA1, DQB1, DRB1 and DPB1) of 6 patients with pemphigus, in whom the disease was "triggered" by drugs containing sulphydryl or another sulphur-containing group. All patients carried the DRB1*0402 susceptibility allele, and one patient also carried the second susceptibility allele, namely DQB1*0503 (in linkage with DRB1*1401). Bacterial, viral or environmental agents are suspected to trigger the onset of autoimmune diseases. Our study demonstrated the presence in patients with drug-triggered pemphigus vulgaris of the same HLA alleles thought to predispose to idiopathic pemphigus vulgaris. This finding strengthens the notion that these HLA alleles may be true disease susceptibility genes.

Pemphigus and dietary factors. In vitro acantholysis by allyl compounds of the genus Allium

BACKGROUND

Today it is generally accepted that every drug that possesses an active thiol group in its molecule is capable of inducing pemphigus in vivo and provoking acantholysis in vitro. We therefore suggested that plants, in particular those belonging to the Allium group, that contain several active compounds with stable disulfide and thiol groups in their molecule may cause the same.

OBJECTIVE

To verify this hypothesis by investigating the in vitro acantholytic effect of three compounds of garlic.

METHODS

Skin samples from donors were cultured in the presence of three compounds of garlic (i.e. allylmercaptan, allylmethylsulfide and allylsulfide) for 3 days. The skin samples were then processed for microscopic control for acantholysis.

RESULTS

Results indicate that, indeed, the three garlic compounds tested are capable of inducing acantholysis in vitro. Focal and diffuse acantholysis was observed in the specimens from 4 out of 7 donors cultured in the presence of 6 and 9 mM of each of the allyl compounds for 3 days. Interestingly, tissues from a DR4+ donor proved to be more acantholysis prone than others, showing large blistering due to diffuse acantholysis, thus indicating that individual susceptibility plays a crucial role also in vitro.

CONCLUSION

Garlic compounds with stable disulfide and thiol groups in their molecule are capable of inducing acantholysis in vitro. These findings lend further support to the theory that 'harmless' nutritional factors are capable of inducing acantholysis in vitro and possibly also in vivo. In view of these findings, it is suggested that nutritional factors should be added to the ever-growing list of exogenous factors capable of inducing pemphigus.

Boron neutron capture therapy: a guide to the understanding of the pathogenesis of late radiation damage to the rat spinal cord

PURPOSE

Before the commencement of new boron neutron capture therapy (BNCT) clinical trials in Europe and North America, detailed information on normal tissue tolerance is required. In this study, the pathologic effects of BNCT on the central nervous system (CNS) have been investigated using a rat spinal cord model.

METHODS AND MATERIALS

The neutron capture agent used was 10B enriched sodium mercaptoundecahydro-closododecaborate (BSH), at a dosage of 100 mg/kg body weight. Rats were irradiated on the thermal beam at the Brookhaven Medical Research Reactor. The large spine of vertebra T2 was used as the lower marker of the irradiation field. Rats were irradiated with thermal neutrons alone to a maximum physical absorbed dose of 11.4 Gy, or with thermal neutrons in combination with BSH, to maximum absorbed physical doses of 5.7 Gy to the CNS parenchyma and 33.7 Gy to the blood in the vasculature of the spinal cord. An additional group of rats was irradiated with 250 kVp X rays to a single dose of 35 Gy. Spinal cord pathology was examined between 5 and 12 months after irradiation.

RESULTS

The physical dose of radiation delivered to the CNS parenchyma, using thermal neutron irradiation in the presence of BSH, was a factor of two to three lower than that delivered to the vascular endothelium, and could not account for the level of damage observed in the parenchyma.

CONCLUSION

The histopathological observations of the present study support the hypothesis that the blood vessels, and the endothelial cells in particular, are the critical target population responsible for the lesions seen in the spinal cord after BNCT type irradiation and by inference, after more conventional irradiation modalities such as photons or fast neutrons.

Clinical phase-I study of Na2B12H11SH (BSH) in patients with malignant glioma as precondition for boron neutron capture therapy (BNCT)

PURPOSE

Within the European collaboration on boron neutron capture therapy (BNCT), a clinical Phase I study is being carried out to establish BNCT as an alternative treatment modality for malignant glioma (WHO III/IV). Data about the pharmacokinetics, biodistribution and toxicity of the boron compound Na2B12H11SH (BSH) are of great importance to avoid radiation damage of healthy tissue and to deliver a sufficient radiation dose.

METHODS AND MATERIALS

Twenty four patients suffering from a glioblastoma multiforme entered the study to date, infused with a maximum concentration of up to 50 mg BSH/kg. Boron concentration measurements in tissues, urine, and blood were carried out, using inductively coupled plasma-atomic spectroscopy (ICP-AES) and quantitative neutron capture radiography (QNCR). A cross-calibration of these boron determination techniques was carried out.

RESULTS

In tumor tissue, confirmed by histopathology of small biopsies, we found a consistently high but heterogeneous boron uptake. Necrotic parts contain much lower amounts of boron; normal brain tissue has shown no significant uptake. In skin, bone, muscle, and dura mater only small amounts of boron were found. In blood samples, we found biphasic kinetics, but with variations of the half-lives from patient to patient. The compound is mainly excreted through the urine, but an additional entero-hepatic pathway can be demonstrated. Systematic investigations revealed no toxic side effect of the intravenously administered BSH. Comparable data were obtained by using ICP-AES and QNCR for boron concentration measurements.

CONCLUSION

Taking into account the radiobiological considerations of the neutron beam source, we found promising facts that BNCT could be a useful irradiation method for highly malignant brain tumors. Favorable amounts of the boron compound BSH were found in tumor tissue, whereas healthy brain tissue has shown no significant uptake.

Possible nutritional factors in induced pemphigus

Today it is generally accepted that every drug that possesses an active thiol group in its molecule is capable of inducing pemphigus. Some plants, in particular those belonging to the Allium group, contain several active compounds with stable disulfide and thiol groups in their molecule. The Allium group contains many important vegetables like onion, leek and garlic. Examples of molecules with an active thiol group are: CH2 = CH-CH2-S-S-CH2-CH = CH2 (diallyl disulfide) or CH2 = CH-CH2-S(O)S-CH2-CH = CH2 (allicin). It is suggested that some foods, in particular vegetables of the Allium group that contain active thiol groups in their molecule, could contribute to the induction of pemphigus. In general, nutritional factors should be added to the list of exogenous factors that are capable of inducing pemphigus.