Islatravir Is Not Expected to Be a Victim or Perpetrator of Drug-Drug Interactions via Major Drug-Metabolizing Enzymes or Transporters.

Islatravir (MK-8591) is a nucleoside reverse transcriptase translocation inhibitor in development for the treatment and prevention of HIV-1. The potential for islatravir to interact with commonly co-prescribed medications was studied in vitro. Elimination of islatravir is expected to be balanced between adenosine deaminase-mediated metabolism and renal excretion. Islatravir did not inhibit uridine diphosphate glucuronosyltransferase 1A1 or cytochrome p450 (CYP) enzymes CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6, or 3A4, nor did it induce CYP1A2, 2B6, or 3A4. Islatravir did not inhibit hepatic transporters organic anion transporting polypeptide (OATP) 1B1, OATP1B3, organic cation transporter (OCT) 1, bile salt export pump (BSEP), multidrug resistance-associated protein (MRP) 2, MRP3, or MRP4. Islatravir was neither a substrate nor a significant inhibitor of renal transporters organic anion transporter (OAT) 1, OAT3, OCT2, multidrug and toxin extrusion protein (MATE) 1, or MATE2K. Islatravir did not significantly inhibit P-glycoprotein and breast cancer resistance protein (BCRP); however, it was a substrate of BCRP, which is not expected to be of clinical significance. These findings suggest islatravir is unlikely to be the victim or perpetrator of drug-drug interactions with commonly co-prescribed medications, including statins, diuretics, anti-diabetic drugs, proton pump inhibitors, anticoagulants, benzodiazepines, and selective serotonin reuptake inhibitors.

A Phase 1 Study to Evaluate the Drug Interaction Between Islatravir (MK-8591) and Doravirine in Adults Without HIV.

BACKGROUND AND OBJECTIVES: Islatravir (MK-8591) is a novel nucleoside analogue in development for the treatment and prevention of HIV-1 infection. Doravirine is a non-nucleoside reverse transcriptase inhibitor indicated for the treatment of HIV-1 infection. This study evaluated the pharmacokinetics, safety, and tolerability of islatravir and doravirine coadministration in a double-blind, placebo-controlled, randomized, fixed-sequence study. METHODS: Adult participants without HIV infection were administered oral doravirine 100 mg (n = 10) or placebo (n = 4) once daily (QD) for 5 days, immediately followed by oral islatravir 2.25 mg (n = 10) or placebo QD (n = 4) for 14 days; islatravir 2.25 mg and doravirine 100 mg QD, or placebo QD, were then coadministered for 5 days. Pharmacokinetic and safety data were collected. RESULTS: Doravirine geometric least-squares mean ratios (90% confidence intervals (CIs)) of (doravirine + islatravir)/doravirine for the area under the plasma drug concentration-time curve over 24 h (AUC0-24h), maximum plasma concentration (Cmax), and plasma concentration at 24 h post-dose (C24h) were not meaningfully impacted. Islatravir geometric least-squares mean ratios (90% CI) of (islatravir + doravirine)/islatravir for AUC0-24h and Cmax were both close to unity, 1.06 (1.01, 1.12) and 1.08 (0.91, 1.27), respectively. All study regimens were generally well tolerated. CONCLUSION: These results indicate that coadministration of islatravir and doravirine had no clinically meaningful effect on the pharmacokinetics of either drug, and support further clinical investigation of islatravir in combination with doravirine for the treatment of HIV-1 infection.

Effects of islatravir (4'-ethynyl-2-fluoro-2'-deoxyadenosine or EFdA) on renal tubular cells and islatravir's interactions with organic anion transporters.

Islatravir (ISL; 4'-ethynyl-2-fluoro-2'-deoxyadenosine or EFdA) is a novel reverse transcriptase translocation inhibitor and has a unique structure and high antiviral activity against wild-type and multidrug resistant HIV strains. In this study, we investigated whether islatravir (ISL) can cause kidney damage compared to tenofovir disoproxil fumarate (TDF) and tenofovir (TFV). We also investigated interactions of these drugs with organic anion transporters (OATs). There is a large gap in ISL concentration between the pharmacological dose to proximal tubular cells and the clinical dose. ISL is unlikely to be taken up via OAT1 or OAT3; therefore, OAT1 and OAT3 may not be involved in the injury to tubular cells. Present data strongly suggests that ISL is not toxic to proximal tubules because blood levels of ISL are not high enough to cause kidney damage in the clinical setting.

Cross-sectional and longitudinal associations between urinary zinc and lung function among urban adults in China.

BACKGROUND: Exposure to zinc was suggested to be associated with pulmonary damage, but whether zinc exposure affects lung function remains unclear. OBJECTIVES: To quantify the association between urinary zinc and lung function and explore the potential mechanisms. METHODS: Urinary zinc and lung function were measured in 3917 adults from the Wuhan-Zhuhai cohort and were repeated after 3 years of follow-up. Indicators of systemic inflammation (C reactive protein), lung epithelium integrity (club cell secretory protein-16) and oxidative damage (8-hydroxy-2'-deoxyguanosine and 8-isoprostane) were measured at baseline. Linear mixed models were used to estimate the exposure-response relationship between urinary zinc and lung function. Mediation analyses were conducted to assess mediating roles of inflammation and oxidative damage in above relationships. RESULTS: Each 1-unit increase in log-transformed urinary zinc values was associated with a 35.72 mL decrease in forced vital capacity (FVC) and a 24.89 mL decrease in forced expiratory volume in 1 s (FEV1) in the baseline analyses. In the follow-up analyses, there was a negative association between urinary zinc and FVC among participants with persistent high urinary zinc levels, with an estimated change of -93.31 mL (95% CI -178.47 to -8.14). Furthermore, urinary zinc was positively associated with restrictive ventilatory impairment. The mediation analyses suggested that C reactive protein mediated 8.62% and 8.71% of the associations of urinary zinc with FVC and FEV1, respectively. CONCLUSION: Urinary zinc was negatively associated with lung function, and the systemic inflammation may be one of the underlying mechanisms.

Dynamic Changes in DNA Damage and Repair Biomarkers with Employment Length among Nickel Smelting Workers.

Our study explored the dynamic changes in and the relationship between the DNA damage marker 8-hydroxy-2'-deoxyguanosine (8-OHdG) and the DNA repair marker 8-hydroxyguanine DNA glycosidase 1 (hOGG1) according to the length of occupational employment in nickel smelting workers. One hundred forty nickel-exposed smelting workers and 140 age-matched unexposed office workers were selected from the Jinchang cohort. The 8-OHdG levels in smelting workers was significantly higher than in office workers (Z=-8.688, P<0.05) and the 8-OHdG levels among nickel smelting workers in the 10-14 y employment length category was significantly higher than among all peers. The hOGG1 levels among smelting workers were significantly lower than those of non-exposed workers (Z=-8.948, P<0.05). There were significant differences between employment length and hOGG1 levels, with subjects employed in nickel smelting for 10-14 y showing the highest levels of hOGG1. Correlation analysis showed positive correlations between 8-OHdG and hOGG1 levels (r=0.413; P<0.01). DNA damage was increased with employment length among nickel smelting workers and was related to the inhibition of hOGG1 repair capacity.

8-Oxo-7,8-dihydroguanine and 8-oxo-7,8-dihydro-2'-deoxyguanosine concentrations in various human body fluids: implications for their measurement and interpretation.

8-Oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) is the most investigated product of oxidatively damaged DNA lesion that has been associated with the development of aging, cancer and some degenerative diseases. Here, we present the first liquid chromatography-tandem mass spectrometry method that enables the simultaneous measurement of its repair products in plasma and saliva, namely 8-oxo-7,8-dihydroguanine (8-oxoGua) and 8-oxodGuo. Using this method, we investigated the underlying transport mechanism of the repair products of oxidatively damaged DNA between cellular compartments and biological matrices. Plasma, saliva and urine samples were collected concurrently from 57 healthy subjects. Various deproteinization methods were evaluated, and the precipitants acetonitrile and sodium hydroxide-methanol were, respectively, selected for plasma and saliva samples due to their effect on recovery efficiencies and chromatography. The mean baseline concentrations of 8-oxoGua and 8-oxodGuo in plasma were demonstrated to be 0.21 and 0.016 ng/mL, respectively, while in saliva they were 0.85 and 0.010 ng/mL, respectively. A relatively high concentration of 8-oxoGua was found in saliva with a concentration factor (CF, concentration ratio of saliva to plasma) of 4 as compared to that of 8-oxodGuo (CF: 0.6), implying that 8-oxoGua in plasma may be actively transported to saliva, whereas 8-oxodGuo was most dependent on a passive diffusion. Good correlations between urine and plasma concentrations were observed for 8-oxoGua and 8-oxodGuo, suggesting that blood was a suitable matrix in addition to urine. Significant correlation between 8-oxoGua and 8-oxodGuo in urine was only observed when the concentrations were not corrected for urinary creatinine, raising the issue of applicability of urinary creatinine to adjust 8-oxoGua concentrations.

Metformin decreases serum 8-hydroxy-2'-deoxyguanosine levels in polycystic ovary syndrome.

OBJECTIVE: To learn whether metformin treatment affects oxidative stress as measured by serum concentrations of 8-hydroxy-2'-deoxyguanosine (8-OHdG). DESIGN: Double-blind, randomized, placebo-controlled trial. SETTING: University outpatient clinic. PATIENT(S): The study cohort consisted of 50 obese women (body mass index [BMI] ≥ 27 kg/m(2)) and 60 nonobese patients (BMI <27 kg/m(2)), mean age was 27.7 ± 4.0 SD years. INTERVENTION(S): Randomization to receive metformin or placebo for 3 months. MAIN OUTCOME MEASURE(S): Serum levels of 8-OHdG before and after medical treatment. RESULT(S): The levels of 8-OHdG were equal at baseline in the placebo and metformin groups. Obese women had higher baseline serum concentrations of 8-OHdG. Levels of 8-OHdG were statistically significantly reduced with metformin treatment, especially in obese patients with polycystic ovary syndrome. This study was a secondary subanalysis of a previously conducted prospective multicenter, randomized, placebo-controlled study on the effects of metformin on miscarriage, pregnancy, and miscarriage rates. CONCLUSION(S): Metformin treatment, compared with placebo, statistically significantly decreased 8-OHdG levels in women with polycystic ovary syndrome. CLINICAL TRIAL REGISTRATION NUMBER: NCT00994812.

Distributions and ranges of values of blood and urinary biomarker of inflammation and oxidative stress in the workers engaged in office machine manufactures: evaluation of reference values.

BACKGROUND: Interleukins, interferons and oxidative DNA products are important biomarkers assessing the inflammations and tissue damages caused by toxic materials in the body. We tried to evaluate distributions, reference values and age related changes of blood levels of inflammatory cytokines, C-reactive protein (CRP), IgE and urine levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG) among workers in a cohort study evaluating the health influences of toner particles. METHODS: A total of 1366 male workers under age 50 years (age 19-49 years; 718 exposed and 648 not exposed to toner particles) in a cross sectional study of 1614 (categorized as 809 exposed and 805 not exposed, age 19-59 years) workers in a photocopier company has been followed prospectively as the cohort. Blood levels of interleukin (IL)-4, IL-6, IL-8, interferon-γ (IFN-γ), CRP, IgE and urine 8-OHdG were measured annually for 5 years. RESULTS: Reference values of the biomarkers are; CRP: 0.01-0.63×10(-2) g/L, IgE: 6-1480 IU/mL, IL-4: 2.6-76.1 pg/mL, IL-6: 0.4-4.9 pg/mL and 8-OHdG: 1.5-8.2 ng/mgCr. We could not evaluate reference values for IL-8 and IFN- γ because most of the values were below the sensitivity limits (2.0 pg/mL and 0.1 IU/mL, respectively). There were no differences of the biomarker levels between the toner exposed and the control workers. We observed a statistically significant age related decrease of serum IL-4 levels. CONCLUSIONS: This is the first report assessing the distributions and reference values of inflammatory biomarker levels in a large scaled cohort. We observed age related changes of some of the biomarkers. We could not detect any differences of the studied biomarker values between the toner exposed and the control workers.

Neonatal screening for severe combined immunodeficiency caused by an adenosine deaminase defect: a reliable and inexpensive method using tandem mass spectrometry.

BACKGROUND: Adenosine deaminase (ADA)-severe combined immunodeficiency (SCID) is an SCID caused by a defect in the enzyme adenosine deaminase. It is usually fatal in infancy because of severe recurrent infections. When diagnosis is made, permanent damage caused by infections or by metabolites is often present. Gene therapy, bone marrow transplantation, or enzyme therapy might be effective if performed early. ADA-SCID complies with all the criteria for inclusion in a newborn screening program. However, screening methods are still expensive or provide a non-negligible number of indeterminate results. OBJECTIVE: The aim of the present study was to develop a simple, reliable, and inexpensive method for diagnosis of ADA-SCID by using dried blood spot (DBS) samples taken at birth. Cost per test was calculated, including the cost for reagents, equipment, and operators. METHODS: DBS samples from 4 patients with genetically confirmed ADA-SCID and 12,020 DBS samples from healthy newborns were examined. Adenosine and 2'-deoxyadenosine were tested by using tandem mass spectrometry (PCT EP2010/070517). RESULTS: The mean levels of adenosine and 2'-deoxyadenosine were 7.8 ± 3.1 and 8.5 ± 6.0 µmol/L, respectively, in affected children; adenosine was found at 0.23 ± 0.09 µmol/L, whereas 2'-deoxyadenosine was never detected in healthy control subjects (adenosine: P < 10(-6) [95% confidence limit, 7.59-7.78] and 2'-deoxyadenosine: P < 10(-6) [95% confidence limit, 8.65-8.82] for control subjects vs patients with ADA-SCID). No indeterminate or false-positive results were found. Cost per test was €0.01 ($0.013). A pilot population-based newborn screening for ADA-SCID has started in Tuscany, Italy. CONCLUSION: Tandem mass spectrometry can be used for diagnosis of one of the most frequent form of SCID at a negligible cost.

Beneficial effects of cordycepin on metabolic profiles of liver and plasma from hyperlipidemic hamsters.

In this study, (1)H NMR-based metabonomics was applied to evaluate the beneficial effects of cordycepin (3'-deoxyadenosine), a natural monomer compound, on endogenous metabolic profiles of liver and plasma from hyperlipidemic Syrian golden hamsters. Hyperlipidemia was successfully established in hamsters fed by a high-fat diet for 2 weeks. The hyperlipidemic hamsters were treated with an oral administration of simvastatin (2 mg kg(- 1)) or cordycepin (140 mg kg(- 1)) for consecutive 4 weeks. The metabolic profiles of plasma and intact liver tissues were established using (1)H NMR spectroscopy. The results showed higher contents of lipids (triglyceride and cholesterol), lactate, acetate, alanine, glutamine together with lower contents of choline-containing compounds (e.g. phosphocholine, phosphatidylcholine, and glycerophosphocholine), glucose, and glycogen in plasma and liver samples from hyperlipidemic hamsters than those in controls. Cordycepin afforded a little lipid-regulating activity on plasma but more beneficial effects on liver, implicating that cordycepin might have a protective effect on liver under fatty liver condition.

Aberrations in one-carbon metabolism induce oxidative DNA damage in sporadic breast cancer.

The authors investigated the role of dietary micronutrients and eight functional polymorphisms of one-carbon metabolism in modulating oxidative stress in sporadic breast cancer. PCR-restriction fragment length polymorphism (RFLP) and PCR-amplified fragment length polymorphism (AFLP) methods were used for genetic analysis in 222 sporadic breast cancer cases and 235 controls. Standardized food frequency questionnaire was used for dietary micronutrient assessment. 8-oxo-2'-deoxyguanosine (8-oxodG), folate, and estradiol were estimated using commercial ELISA kits. Reverse-phase HPLC coupled with fluorescence detector was used for plasma homocysteine analysis. Total glutathione was estimated using Ellman's method. Reduced folate carrier 1 (RFC1) G80A and methylenetetrahydrofolate reductase (MTHFR) C677T were associated with risks of 1.34 (95% CI 1.01-1.79)- and 1.84 (95% CI 1.14-3.00)-folds, respectively, for sporadic breast cancer while cytosolic serine hydroxymethyl transferase (cSHMT) C1420T was associated with reduced risk (OR 0.71, 95% CI 0.53-0.94). Significant increase in plasma 8-oxo-2'-deoxyguanosine (P < 0.004) and homocysteine (P < 0.0001); and significant decrease in total glutathione (P < 0.01) and dietary folate (P = 0.006) was observed in cases than in controls. Oxidative DNA damage showed direct association with menopause (P = 0.02), RFC1 G80A (P < 0.05) and homocysteine (P < 0.0001); and inverse association with dietary folate (P < 0.0001), plasma folate (P < 0.0001), cSHMT C1420T (P < 0.05) and glutathione (P < 0.001). To conclude, the aberrations in one-carbon metabolism induce oxidative stress in sporadic breast cancer either by affecting the folate pool or by impairing remethylation.

Clear differences in levels of a formaldehyde-DNA adduct in leukocytes of smokers and nonsmokers.

Formaldehyde is considered carcinogenic to humans by the IARC, but there are no previous reports of formaldehyde-DNA adducts in humans. In this study, we used liquid chromatography-electrospray ionization-tandem mass spectrometry to quantify the formaldehyde-DNA adduct N(6)-hydroxymethyldeoxyadenosine (N(6)-HOMe-dAdo) in leukocyte DNA samples from 32 smokers of >or=10 cigarettes per day and 30 nonsmokers. Clear peaks coeluting with the internal standard in two different systems were seen in samples from smokers but rarely in nonsmokers. N(6)-HOMe-dAdo was detected in 29 of 32 smoker samples (mean +/- SD, 179 +/- 205 fmol/micromol dAdo). In contrast, it was detected in only 7 of 30 nonsmoker samples (15.5 +/- 33.8 fmol/micromol dAdo; P < 0.001). The results of this study show remarkable differences between smokers and nonsmokers in levels of a leukocyte formaldehyde-DNA adduct, suggesting a potentially important and previously unrecognized role for formaldehyde as a cause of cancer induced by cigarette smoking.

Elevated level of 8-oxo-7,8-dihydro-2'-deoxyguanosine in leukocytes of BRCA1 mutation carriers compared to healthy controls.

Carriers of BRCA1 mutation face highly increased risk of breast and ovarian cancer and some studies with cell culture suggest that the encoded protein may be involved in oxidatively damaged DNA repair. However, no studies concerning a possible link between oxidatively damaged DNA and BRCA1 deficiency have been conducted with the mutations carriers. Therefore, to assess an involvement of BRCA in oxidative damage to DNA in the present study a broad spectrum of parameters reflecting oxidative stress/DNA damage were analyzed in 3 subject groups; (i) carriers of BRCA1 mutations without symptoms of the disease; (ii) patients with breast or ovarian cancer with the mutations and (iii) the group of healthy subjects recruited from among close relatives of the group of carriers without symptoms of the disease. We found that the endogenous levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in leukocytes DNA and excretion rates of urinary 8-oxodG were significantly higher in the cancer patients than in the healthy carriers. Similarly, to the cancer patient group, 8-oxodG level in leukocytes DNA is significantly higher in the carriers group in comparison with control group. That the control group comprised close relatives of the carriers gives further credit to our finding. Since we did not observe substantial differences in the analyzed markers of oxidative stress between the controls and the carriers, the observed increase in the level may be a result of a deficiency in the repair of 8-oxodG.

Typical signature of DNA damage in white blood cells: a pilot study on etheno adducts in Danish mother-newborn child pairs.

The impact of DNA damage commonly thought to be involved in chronic degenerative disease causation is particularly detrimental during fetal development. Within a multicenter study, we analyzed 77 white blood cell (WBC) samples from mother-newborn child pairs to see if imprinting of DNA damage in mother and newborn shows a similar pattern. Two adducts 1,N(6)-ethenodeoxyadenosine (epsilondA) and 3,N(4)-ethenodeoxycytidine (epsilondC) were measured by our ultrasensitive immunoaffinity (32)P-post-labeling method. These miscoding etheno-DNA adducts are generated by the reaction of lipid peroxidation (LPO) end products such as 4-hydroxy-2-nonenal with DNA bases. Mean epsilondA and epsilondC levels when expressed per 10(9) parent nucleotides in WBC-DNA from cord blood were 138 and 354, respectively; in maternal WBC-DNA, the respective values were 317 and 916. Thus, the DNA-etheno adduct levels were reliably detectable and about two times lower in child cord blood, the difference being significant at P < 0.0004. Analysis of epsilondA and epsilondC levels in cord versus maternal blood WBC showed strong positive correlations (R(2) approximately 0.9, P < 0.00001). In conclusion, LPO-induced DNA damage arising from endogenous reactive aldehydes in WBC of both mother and newborn can be reliably assessed by epsilondA and epsilondC as biomarkers. The high correlation of etheno adduct levels in mother and child WBC suggests that a typical signature of DNA damage is induced similarly in fetus and mother. Prospective cohort studies have to reveal whether these two WBC-DNA adducts could serve as risk indicator for developing hematopoietic cancers and other disorders later in life.

Effect of Cordyceps militaris supplementation on sperm production, sperm motility and hormones in Sprague-Dawley rats.

Cordyceps species have been traditionally used as for the enhancement of sexual function, but its direct evidence is lacking. We investigated the spermatogenic effect of Cordyceps militaris (CM) as supplementation with CM mycelium to 7-week-old male Sprague-Dawley (SD) rats. Ninety rats (30 for each group) were selected to regular diet or diet supplemented with CM mycelium (1% and 5%) for 6 weeks. Epididymal sperm were collected from 6 animals per group at each interval of observation. They were allowed to recover for one week. The quality and quantity of sperm were compared in these rats. The CM supplementation resulted in an increase of serum cordycepin concentration (n = 6, each group) that correlated with treatment time and the cordycepin level was significantly higher (p < 0.05) in 5% group as compared to 1% group at the 5th and 6th week. Epididymal sperm count was enhanced significantly from the control, at the 5th week and peaked at the 6th week in both groups supplemented with CM (each time point, n = 6; p < 0.05) and maintained for 2 weeks after stopping the treatment. Increased serum testosterone and estradiol-17 (E2) concentrations were found in rats with the CM supplementation (p < 0.05), but not other hormones such as follicle stimulating hormone (FSH), luteinizing hormone (LH) or prolactin. Importantly, percentages of motile sperm cells were also enhanced significantly (p < 0.05) paralleled the serum testosterone pattern from the supplement groups as compared to the control group. Taken together, these results indicate that supplementation with CM improves sperm quality and quantity in rats.

Total antioxidant status and 8-hydroxy-2'-deoxyguanosine levels in gingival and peripheral blood of periodontitis patients.

INTRODUCTION: The aim of this study was to determine 8-OHdG concentration as a biomarker of oxidant-induced DNA damage and to assess total antioxidant status (TAS) in gingival and peripheral blood during periodontal lesion. MATERIALS AND METHODS: The study included 56 untreated periodontitis patients (26 with aggressive periodontitis, and 30 with chronic periodontitis (CP). The control group consisted of 25 healthy volunteers without pathological changes in the periodontium. Competitive ELISA was used to measure 8-OHdG. A colorimetric method based on the reduction of ABTSo+ radical cation generation was used to measure TAS. RESULTS: Significantly higher 8-OHdG concentrations were detected in the gingival blood in both groups of patients with periodontitis than in the control group. Subjects with CP had significantly decreased TAS levels in the gingival blood compared with the control group. A significantly decreased TAS level in the peripheral blood in both patient groups compared with the control group was found. Significant positive correlation between TAS levels in venous and gingival blood in all the periodontitis patients and in the CP group was observed. CONCLUSIONS: The oxidative burst in periodontitis may lead to significant local damage to nucleic acids. The significantly decreased TAS level in the gingival blood of CP patients compared with the healthy subjects suggests the possibility of a significant decrease in local antioxidant system capacity during the course of periodontitis. The decreased TAS level in the peripheral blood in the group of all patients with periodontitis may be one of the pathogenic mechanisms underlying the links between periodontal disease and several systemic diseases for which periodontitis is regarded as a independent risk factor.

2'-Deoxy-4'-C-ethynyl-2-fluoroadenosine: a nucleoside reverse transcriptase inhibitor with highly potent activity against all HIV-1 strains, favorable toxic profiles and stability in plasma.

A working hypothesis to solve the critical problems of existing HAART was proposed. The study based on the hypothesis proved the validity of the hypothesis and resulted in the development of 2'-deoxy-4'-C-ethynyl-2-fluoro-adenosine (4'Ed2FA), a nucleoside reverse transcriptase inhibitor (NRTI) with highly potent activity against all HIV-1 strains, very favourable toxic profiles, and stability in plasma.

8-hydroxy-2-desoxyguanosine serum concentrations as a marker of DNA damage in patients with classical galactosaemia.

BACKGROUND: Classical galactosaemia is caused by a deficiency of galactose-1-phosphate uridyl transferase, resulting in high galactose (Gal), galactose-1-phosphate (Gal-1-P) and galactitol blood levels. Galactose/lactose restriction intake is the only treatment. 8-hydroxy-2-desoxyguanosine (8-OHdG) is a marker of oxidized DNA damage. AIM: Since galactosaemia outcome is closely related to restriction of Gal intake, we aimed to evaluate correlations between Gal-1-P, total antioxidant status (TAS) and 8-OHdG blood levels in galactosaemic patients on poor or strict diet. METHODS: Venous blood samples were obtained from galactosaemic patients (n = 11) on poor diet (group A) and after 30 d on strict diet (group B). Twenty-eight healthy children were the controls. Gal-1-P and TAS were evaluated in their blood spectrophotometrically and 8-OHdG with an immunoassay. RESULTS: TAS was significantly decreased (905 +/- 112 micromol/l) in patients on a "loose diet" (group A) as compared to those when restored to their diet (group B) (1,340 +/- 112 micromol/l, p < 0.001) and controls (1,558 +/- 115 micromol/l, p < 0.001). As expected, Gal-1-P levels were remarkably increased in group A. 8-OHdG level was twofold higher (0.25 +/- 0.03 ng/ml) in group A than that of group B (0.11 +/- 0.04 ng/ml) and threefold higher than that of the controls (0.08 +/- 0.02 ng/ml). TAS and Gal-1-P inversely correlated to 8-OHdG (r= -0.802, p < 0.001), whereas Gal-1-P positively correlated to 8-OHdG (r = 0.820, p < 0.001) in all the groups. CONCLUSION: a) Low TAS and high Gal-1-P levels are implicated with high 8-OHdG blood levels in galactosaemic patients; b) 8-OHdG may be a sensitive biomarker of DNA damage in patients with classical galactosaemia.

Pharmacokinetic/pharmacodynamic modelling of the anti-hyperalgesic and anti-nociceptive effect of adenosine A1 receptor partial agonists in neuropathic pain.

The objective of this investigation was to characterise the pharmacokinetic-pharmacodynamic correlation of adenosine A1 receptor partial agonists in the chronic constriction injury model of neuropathic pain. Following intravenous administration of 8-methylamino-N6-cyclopentyl-adenosine (MCPA; 10 mg/kg) and 2'deoxyribose-N6-cyclopentyl-adenosine (2'dCPA; 20 mg/kg), the time course of the effect on the mechanical paw pressure threshold was determined in conjunction with plasma concentrations. Population pharmacokinetic/pharmacodynamic analysis was applied to derive individual concentration-effect relationships. A composite model consisting of an E(max) model for the anti-hyperalgesic effect in combination with a linear model for the anti-nociceptive effect accurately described the concentration-effect relationship. For both compounds, a full anti-hyperalgesic effect was observed. The values of the EC50 for the anti-hyperalgesic effect were (mean+/-S.D.): 3170+/-1460 and 2660+/-1200 ng/ml for MCPA and 2'dCPA versus 178+/-51 ng/ml for the reference full agonist 5'deoxyribose-N6-cyclopentyl-adenosine (5'dCPA). The values of the slope for the anti-nociceptive effect were 1.9+/-0.30 and 1.2+/-0.20 g.microl/ng, respectively, versus 55+/-8 g microl/ng for 5'dCPA. Adenosine A1 receptor partial agonists behave as full agonists with regard to the anti-hyperalgesic effect in neuropathic pain, but the anti-nociceptive effect is diminished.

Capillary electrophoresis in diagnosis and monitoring of adenosine deaminase deficiency.

BACKGROUND: The diagnosis and monitoring of severe combined immunodeficiency disease (SCID) attributable to adenosine deaminase (ADA) deficiency requires measurements of ADA, purine nucleoside phosphorylase (PNP), and S-adenosyl-L-homocysteine-hydrolase (SAHH) activity and of deoxyadenosine metabolites. We developed capillary electrophoresis (CE) methods for the detection of key diagnostic metabolites and evaluation of enzyme activities. METHODS: Deoxyadenosine metabolites were separated in 30 mmol/L sodium borate-10 mmol/L sodium dodecyl sulfate (pH 9.80) at 25 degrees C on a 60-cm uncoated capillary. For determination of enzyme activities, substrate-product separation and measurements were carried out in 20 mmol/L sodium borate (pH 10.00) at 25 degrees C on a 42-cm uncoated capillary. RESULTS: Deoxynucleotides and deoxyadenosine were readily detectable in erythrocytes and urine, respectively. Both methods were linear in the range 2-500 micro mol/L (r >0.99). Intra- and interassay CV were <4%. Enzyme activities were linear with respect to sample amounts in the incubation mixture and to incubation time (r >0.99 for both). In erythrocytes from healthy individuals, mean (SD) ADA activity was 5619 (2584) nmol/s per liter of packed cells. In erythrocytes of SCID patients at diagnosis, ADA activity was 56.9 (48.3) nmol/s per liter of packed cells; SAHH activity was also much reduced. PNP activity was similar in patients and controls. CONCLUSIONS: CE can be used to test ADA deficiency and enables rapid assessment of ADA expression in hematopoietic cells of SCID patients during therapy.