Simultaneous determination of albendazole sulfoxide enantiomers and albendazole sulfone in plasma

A high-performance liquid chromatographic method has been developed for the simultaneous determination of albendazole sulfoxide (ABZSO) enantiomers and albendazole sulfone (ABZSO₂) in human plasma. The resolution of ABZSO enantiomers and ABZSO₂ was obtained on a Chiralpak^® AD column using hexane–isopropanol–ethanol (81:14.25:4.75, v/v/v) as the mobile phase. The drugs were detected by fluorescence (λ_exc=280 nm, λ_em=320 nm). The drugs were extracted from 500 μl plasma with ethyl acetate, and after solvent evaporation, the residues were dissolved in the mobile phase and chromatographed. The method was precise and accurate for the three compounds, as judged by the coefficients of variation and relative errors observed. Linear standard curves were obtained in the concentration range of 5–2500 ng/ml for ABZSO enantiomers and 1–500 ng/ml for ABZSO₂. A typical plasma concentration–time profile is presented for one patient under treatment for neurocysticercosis.     

Dose-dependent activity of albendazole against benzimidazole-resistant nematodes in sheep: relationship between pharmacokinetics and efficacy

The relationship between the pharmacokinetic behaviour and the anthelmintic efficacy of albendazole (ABZ) against benzimidazole (BZD)-resistant nematodes was studied in sheep. A micronized ABZ suspension was orally administered at two different dose levels to sheep naturally infected with BZD-resistant gastrointestinal (GI) nematodes. The experimental animals were allocated into the following groups (n = 8): (a) untreated control; (b) orally treated with ABZ at 3.8 mg/kg b.w.; and (c) orally treated with ABZ at 7.5 mg/kg b.w. Plasma samples were obtained serially over 72 h post-treatment from both treated groups and analysed by HPLC to measure the concentrations of ABZ and its sulphoxide (ABZSO) and sulphone (ABZSO(2)) metabolites. Faecal egg counts were performed prior to treatment and at the necropsy day. All experimental animals were sacrificed 10 days after treatment to perform GI worm counts. While ABZ parent drug was not recovered in the bloodstream, ABZSO and ABZSO(2) were the molecules found in plasma. ABZSO was the metabolite measured at the highest concentrations in the bloodstream for up to 36 (treatment at 3.8 mg/kg) or 60 h (treatment at 7.5 mg/kg) post-administration. There was a proportional relationship between the administered ABZ dose and the measured plasma concentrations of both ABZ metabolites. Over a 100% increment on the plasma AUC values for the anthelmintically active ABZSO metabolite was observed at the 7.5 mg/kg compared to the 3.8 mg/kg treatment. The low efficacy patterns (< 24%) observed against the GI nematodes investigated indicate a high level of resistance to ABZ given at 3.8 mg/kg an efficacious therapeutic dose rate recommended in some countries. However, the higher and prolonged plasma drug concentration measured after the 7.5 mg/kg treatment resulted in an improved efficacy pattern (estimated by both faecal egg and adult worm counts) against most of the GI nematodes studied compared to that obtained at the lower dose rate. A direct relationship between drug pharmacokinetic behaviour and anthelmintic efficacy against BZD-resistant nematodes in sheep was shown in the current work, although individual variation precluded the observation of statistically significant differences in worm counts.     

Simultaneous liquid chromatography-tandem mass spectrometric determination of albendazole sulfoxide and albendazole sulfone in plasma

This paper describes a simple, fast, sensitive and reliable method for the simultaneous determination of albendazole sulfoxide (ASOX) and albendazole sulfone (ASON), the two most important metabolites of the drug albendazole (ABZ), in plasma samples using liquid chromatography and tandem mass spectrometry. After liquid-liquid extraction with dichloromethane, the two albendazole metabolites and the internal standard phenacetin were resolved in a CN column using the mobile phase methanol-water (4:6, v/v) acidified with 1% acetic acid. Detection by electrospray mass spectrometry was carried out in the positive ion mode. The method was linear up to 2500 and 250 ng/ml for ASOX and ASON, respectively, with mean recoveries of more than 85%. The precision and accuracy data, based on within- and between-day variations over 5 days, were lower than 15%. The quantitation limits of 0.5 and 5.0 ng/ml for ASON and ASOX are low enough for the method to be suitable for pharmacokinetic studies. Pharmacokinetic data obtained with the proposed method following oral administration of ABZ to a patient with neurocysticercosis are also reported.     

Interaction of benzimidazole anthelmintics with Haemonchus contortus tubulin: binding affinity and anthelmintic efficacy

The ability of various benzimidazoles (BZs) to bind tubulin under different conditions was assessed by determining their IC50 values (the concentration of unlabeled drug required to inhibit 50% of the labeled drug binding), Ka (the apparent equilibrium association constant) and Bmax (the maximum binding at infinite [BZ] = [drug-receptor]). The ability of unlabeled benzimidazoles--fenbendazole, mebendazole (MBZ), oxibendazole (OBZ), albendazole (ABZ), rycobendazole (albendazole sulfoxide, ABZSO), albendazole sulfone, oxfendazole (OFZ), and thiabendazole--to bind tubulin was determined from their ability to inhibit the binding of [3H]MBZ or [3H]OBZ to tubulin in supernatants derived from unembryonated eggs or adult worms of Haemonchus contortus. The binding constants (IC50, Ka, and Bmax) correlated with the known anthelmintic potency (recommended therapeutic doses) of the BZ compounds except for OFZ and ABZSO whose Ka values were lower than could be expected from anthelmintic potency. The binding of [3H]ABZ or [3H]OFZ to tubulin in supernatants derived from BZ-susceptible and BZ-resistant H. contortus was compared. [3H]ABZ demonstrated saturable high-affinity binding but [3H]OFZ bound with low affinity. The high-affinity binding of [3H]ABZ was reduced for the R strain. Tubulin bound BZ drugs at 4 degrees C with lower apparent Ka than at 37 degrees C.     

Study of the in vitro bioactivation of albendazole in human liver microsomes and hepatoma cell lines

The metabolism of albendazole (ABZ), a benzimidazole anthelminthic, was studied in either microsomal preparations of human liver biopsies or cultured human hepatoma cell lines. Metabolites were analyzed by HPLC. Our data show that microsomes from human biopsies and two human cell lines, HepG2 and Hep3B, oxidize the drug to the sulfoxide very efficiently, whereas the third cell line tested, SK-HEP-1, does not. Both cytochrome P-450 dependent monooxygenases and favin-containing monooxygenases appear to be involved in human ABZ metabolism. Using the cell line displaying the highest ABZ-metabolizing activity, HepG2, the cytotoxic and the inducing effects of the parent drug ABZ and of two primary metabolites, the sulfoxide and the sulfone were studied. These three chemicals provoked a rise in mitotic index resulting from cell division blockage at the prophase or at the metaphase (ABZ metabolites) stage, and ABZ was more cytotoxic than its metabolites. With regard to enzyme-inducing effects, our data clearly demonstrate that the sulfoxide and, to a lesser degree, the sulfone are potent inducers of some drug metabolizing enzymes (i.e., cytochrome P-488 dependent monooxygenases and UDP glucuronyltransferase), whereas ABZ fails to increase and even slightly decreases these enzymatic activities. In conclusion, the HepG2 human hepatoma cell line appears to be suitable for the study of many parameters of metabolism and action of ABZ and other structurally related compounds in humans.Abbreviations ABZ albendazole - B[a]P benzo[a]pyrene - HPLC high-performance liquid chromatography - MC 3-methylcholanthrene - MFO mixed-function oxidase - UDPGT UDP-glucuronyltransferase     

Non-disjunction events induced by albendazole in human cells

Albendazole (ABZ), a benzimidazole carbamate used for the treatment of several human helminthiases has high affinity for tubulin, which results in an inhibition of microtubule polymerization, blocking several vital processes in the parasites, such as motility and nutrient uptake. The ability of ABZ to act as mitotic spindle poison leads to a potential risk for aneuploidy induction in exposed human beings. ABZ, as well as albendazole sulphoxide (ABZSO), its main metabolite, induce micronuclei in human cells in a dose-dependent manner. Despite recognition that ABZ and ABZSO increase micronucleus frequency, their potential as inducers of non-disjunction in human cells, an event considered more frequent than chromosome loss, and one of the main mechanisms involved in aneuploidy induction, has not been evaluated. In the present work, we investigated the ability of ABZ and ABZSO to induce non-disjunction in cultured human lymphocytes. Non-disjunction was scored by chromosome-specific FISH using a classical or alpha satellite probe for chromosomes 1 and 7, respectively. Significant increase in non-disjunction events that involved either chromosome were observed in cells treated with ABZ or ABZSO. Both ABZ and ABZSO induced non-disjunction at lower concentrations than those at which MN were observed.     

Enantioselective analysis of albendazole sulfoxide in plasma using the chiral stationary phase

We present a method for the enantioselective analysis of albendazole sulfoxide (ABZSO) in plasma for application in clinical pharmacokinetic studies. ABZSO enantiomers were separated on a 5-μm Chiralcel OB-H® column (4.6 × 150 mm) using hexane:ethanol (93:7, v/v) as the mobile phase and fluorescence detection. ABZSO was extracted with chloroform:isopropanol (8:2, v/v) from 500-μl aliquots of acidified plasma, with full drug recovery. The proposed method presented quantitation limits of 20 ng/ml for (−)ABZSO and 50 ng/ml for (+)ABZSO and was linear up to a concentration of 5,000 ng/ml of each enantiomer. Chirality 9:722–726, 1997. © 1997 Wiley-Liss, Inc.     

Albendazole failure to control resistant nematodes in lambs: lack of effect of fasting-induced improvement on drug absorption

Enhanced plasma availability of albendazole sulphoxide (ABZSO), the active metabolite of albendazole (ABZ), has been described in feed-restricted sheep. The aim of the present work was to determine if the absorption-related pharmacokinetic changes derived from fasting animals prior to drug treatment would modify the clinical efficacy of ABZ against resistant gastrointestinal nematodes in lambs. Forty Corriedale lambs, naturally infected with resistant gastrointestinal nematodes, were divided into 4 groups. Controls were fed ad libitum and did not receive any drug treatment. Treated animals were fed ad libitum up to 30 min prior to treatment with ABZ (3.8 mg/kg) by the intraruminal route. The control (fasted) animals were not fed during the 24-hr period prior to the start of the experiment and did not receive any drug treatment. A second treated group of animals were fasted 24 hr prior to the treatment with ABZ, as previously described for the fed-treated group. Blood samples were collected over a period of 72 hr post-treatment from 6 animals in each treated group. Plasma samples were analyzed by high performance liquid chromatography. The pharmacokinetic parameters were statistically compared using parametric statistical tests. The estimation of the efficacy of the different treatments was performed by the fecal egg count reduction test (FECRT). Additionally, 4 animals randomly chosen from the control-fed and treated groups were killed 13 days post-treatment to evaluate the efficacy against different adult nematode parasites. The results were statistically compared by parametric and non-parametric tests. Significantly (P < 0.05) higher Cmax and AUC values were observed for both the ABZSO and ABZ-sulphone (ABZSO(2)) metabolites in the fasted compared to the fed animals. These kinetic results may be due to a fasting-induced delay in the GI transit time which increases ABZ dissolution and GI absorption. However, a poor ABZ efficacy (measured as FECRT), compatible with a high degree of nematode resistance, was obtained in both fed (48%) and fasted (49%) animals. Haemonchus contortus and Trichostrongylus colubriformis appeared as the more reluctant species with respect to ABZ treatment. The efficacy against H. contortus ranged between 37 (fed) and 54% (fasted) and against T. colubriformis between 0% (fed) and 16% (fasted). Under these experimental conditions, the fasting-induced improvement on ABZ systemic availability (>60%) did not improve its activity against nematodes with a high degree of resistance. However, the data described here for a highly resistant nematode population should not discourage the use of fasting as a practical and well-proven management tool for parasite control in ruminants.     

Efficacy of Albendazole-Chitosan Microsphere-based Treatment for Alveolar Echinococcosis in Mice

This study aimed to investigate the pharmacology and anti-parasitic efficacy of albendazole–chitosan microspheres (ABZ-CS-MPs) for established intraperitoneal infections of Echinococcus multilocularis metacestodes in an experimental murine model. Male outbred Kunming mice infected with E. multilocularis Metacestodes were administered with three ABZ formulations, namely, ABZ-CS-MPs, Liposome–Albendazole (L-ABZ), and albendazole tablet (ABZ-T). Each of the ABZ formulations was given orally at three different doses of 37.5, 75, and 150mg/kg, three times a week for 12 weeks postinfection. After administering the drugs, we monitored the pharmacological performance and anti-parasitic efficacy of ABZ-CS-MPs compared with L-ABZ, and ABZ-T treated mice. ABZ-CS-MPs reduced the weight of tissues containing E. multilocularis metacestodes most effectively compared with the ABZ-T group and untreated controls. Metacestode grown was Highly suppressed during treatment with ABZ-CS-MPs. Significantly higher plasma levels of ABZ metabolites were measured in mice treated with ABZ-CS-MPs or L-ABZ compared with ABZ-T. In particular, enhanced ABZ-sulfoxide concentration profiles were observed in the mice given 150mg/kg of ABZ-CS-MPs, but not in the mice treated with L-ABZ. Histological examination showed that damages caused disorganization of both the germinal and laminated layers of liver hyatid cysts, demolishing their characteristic structures after treatment with ABZ-CS-MPs or L-ABZ. Over time, ABZ-CS-MPs treatment induced a shift from Th2-dominant to Th1-dominant immune response. CS-MPs As a new carrier exhibited improved absorption and increased bioavailability of ABZ in the treatment of E. multilocularis infections in mice.     

Biotransformation of albendazole by fungi

Twenty-five fungal cultures were screened for their ability to transform the anthelmintic drug albendazole. A filamentous fungi Cunninghamella blakesleeana transformed albendazole to three metabolites in significant quantities. The transformation of albendazole was identified by HPLC. Based on the LC-MS-MS data, two metabolites were predicted to be albendazole sulfoxide and albendazole sulfone, the major mammalian metabolites reported previously. A new N-methylated metabolite of albendazole sulfoxide was also produced, where the methylation took place on the N-atom of the imidazole ring system. A temperature of 30°C, pH of 8 and high substrate concentrations produced highest transformation of albendazole. Among the various concentrations studied, 2% w/v of glucose produced highest transformation. The results reveal that the microbial model can be used to produce large quantities of mammalian metabolites.     

Direct separation of albendazole sulfoxide enantiomers by liquid chromatography on a chiral column deriving from (S)-N-(3,5-dinitrobenzoyl) tyrosine: application to enantiomeric assays on plasma samples

The direct enantiomeric resolution of albendazole sulfoxide (SOABZ), an anthelmintic drug belonging to the benzimidazole class, is reported on a chiral stationary phase (CSP) synthesized by covalent binding of (S)-N-(3,5-dinitrobenzoyl)tyrosine-O-(2-propen-1-yl) methyl ester on a gamma-mercaptopropyl-silanized silica gel. A comparison with the resolution achieved on commercially available Pirkle-type CSPs obtained from N-(3,5-dinitrobenzoyl) derivatives of (R)-phenyglycine or (S)-phenylalanine is described. Some structurally related chiral sulfoxides including oxfendazole (SOFBZ) are also studied. Optimization of the mobile phase nature and composition is investigated showing that a hexane-dioxane-ethanol ternary mixture affords an almost baseline resolution (Rs = 1.25); however, in this case, albendazole sulfone (SO2ABZ) is eluted between the two sulfoxide enantiomers; accordingly, a hexane-ethanol mobile phase would be preferred for biological samples containing both metabolites. The influence of temperature on the resolution is depicted with a hexane-ethanol mobile phase. Finally, application to the enantiomeric assays of SOABZ in plasmatic extracts of rat, sheep, bovin, and man after oral administration of albendazole (sulfoxidized to SOABZ and SO2ABZ) is reported. Some distortions in the enantiomeric ratios are evidenced depending on the species.     

Pharmacokinetics of oral moxidectin in individuals with Onchocerca volvulus infection

BackgroundOnchocerciasis (“river blindness”), is a neglected tropical disease caused by the filarial nematode Onchocerca volvulus and transmitted to humans through repeated bites by infective blackflies of the genus Simulium. Moxidectin was approved by the United States Food and Drug Administration in 2018 for the treatment of onchocerciasis in people at least 12 years of age. The pharmacokinetics of orally administered moxidectin in 18- to 60-year-old men and women infected with Onchocerca volvulus were investigated in a single-center, ivermectin-controlled, double-blind, randomized, single-ascending-dose, ascending severity of infection study in Ghana.Methodology/Principal findingsParticipants were randomized to either a single dose of 2, 4 or 8 mg moxidectin or ivermectin. Pharmacokinetic samples were collected prior to dosing and at intervals up to 12 months post-dose from 33 and 34 individuals treated with 2 and 4 mg moxidectin, respectively and up to 18 months post-dose from 31 individuals treated with 8 mg moxidectin. Moxidectin plasma concentrations were determined using high-performance liquid chromatography with fluorescence detection. Moxidectin plasma AUC_0-∞ (2 mg: 26.7–31.7 days*ng/mL, 4 mg: 39.1–60.0 days*ng/mL, 8 mg: 99.5–129.0 days*ng/mL) and C_max (2mg, 16.2 to17.3 ng/mL, 4 mg: 33.4 to 35.0 ng/mL, 8 mg: 55.7 to 74.4 ng/mL) were dose-proportional and independent of severity of infection. Maximum plasma concentrations were achieved 4 hours after drug administration. The mean terminal half-lives of moxidectin were 20.6, 17.7, and 23.3 days at the 2, 4 and 8 mg dose levels, respectively.Conclusion/SignificanceWe found no relationship between severity of infection (mild, moderate or severe) and exposure parameters (AUC_0-∞ and C_max), T_1/2 and T_max for moxidectin. T_max, volume of distribution (V/F) and oral clearance (CL/F) are similar to those in healthy volunteers from Europe. From a pharmacokinetic perspective, moxidectin is an attractive long-acting therapeutic option for the treatment of human onchocerciasis.     

Development and Validation of a High-Performance Liquid Chromatography–Tandem Mass Spectrometry Method for the Simultaneous Determination of Irinotecan and Its Main Metabolites in Human Plasma and Its Application in a Clinical Pharmacokinetic Study

Irinotecan is currently used in several cancer regimens mainly in colorectal cancer (CRC). This drug has a narrow therapeutic range and treatment can lead to side effects, mainly neutropenia and diarrhea, frequently requiring discontinuing or lowering the drug dose. A wide inter-individual variability in irinotecan pharmacokinetic parameters and pharmacodynamics has been reported and associated to patients’ genetic background. In particular, a polymorphism in the UGT1A1 gene (UGT1A1*28) has been linked to an impaired detoxification of SN-38 (irinotecan active metabolite) to SN-38 glucuronide (SN-38G) leading to increased toxicities. Therefore, therapeutic drug monitoring of irinotecan, SN-38 and SN-38G is recommended to personalize therapy. In order to quantify simultaneously irinotecan and its main metabolites in patients’ plasma, we developed and validated a new, sensitive and specific HPLC–MS/MS method applicable to all irinotecan dosages used in clinic. This method required a small plasma volume, addition of camptothecin as internal standard and simple protein precipitation. Chromatographic separation was done on a Gemini C18 column (3 μM, 100 mm x 2.0 mm) using 0.1% acetic acid/bidistilled water and 0.1% acetic acid/acetonitrile as mobile phases. The mass spectrometer worked with electrospray ionization in positive ion mode and selected reaction monitoring. The standard curves were linear (R² ≥0.9962) over the concentration ranges (10–10000 ng/mL for irinotecan, 1–500 ng/mL for SN-38 and SN-38G and 1–5000 ng/mL for APC) and had good back-calculated accuracy and precision. The intra- and inter-day precision and accuracy, determined on three quality control levels for all the analytes, were always <12.3% and between 89.4% and 113.0%, respectively. Moreover, we evaluated this bioanalytical method by re-analysis of incurred samples as an additional measure of assay reproducibility. This method was successfully applied to a pharmacokinetic study in metastatic CRC patients enrolled in a genotype-guided phase Ib study of irinotecan administered in combination with 5-fluorouracil/leucovorin and bevacizumab.     

三疣梭子蟹蜕皮周期中MIH基因mRNA水平与蜕皮激素浓度变化

甲壳动物的蜕皮过程被认为是由位于眼柄的X器-窦腺复合体(XO-SG)分泌蜕皮抑制激素(MIH)通过调节Y器(YO)合成蜕皮激素而调控的。通过实时荧光定量PCR(qRT-PCR)发现MIH基因在三疣梭子蟹眼柄X器-窦腺复合体中表达最强。采用qRT-PCR分析了MIH基因在三疣梭子蟹蜕皮周期中的表达变化, 结果表明; A期为(0.42±0.08)倍, B期为(1.09±0.09)倍, C期为(1.35±0.16)倍, D₀亚期为(1.00±0.10)倍, D₁亚期(0.78±0.07)倍, D₂亚期为(0.27±0.08)倍, D_3/4亚期为(0.20±0.04)倍。采用高效液相色谱-电喷雾串联质谱(LC-MS/MS)法完成了三疣梭子蟹蜕皮周期中蜕皮激素(20E)浓度变化的测定。A/B期蜕皮激素的浓度较低, 低于仪器检测限0.33 pg, C期为(1.666±0.762) ng/mL, D₀亚期为(4.047±1.5133) ng/mL, D₁亚期为(6.756±4.928) ng/mL, D₂亚期为(8.609±3.827) ng/mL, D₃亚期为(19.534±4.799) ng/mL, D₄亚期为11.616 ng/mL。在三疣梭子蟹蜕皮周期中, MIH基因表达量与血淋巴中蜕皮激素浓度呈现一定拮抗性, 揭示MIH抑制Y器合成蜕皮激素而调控着三疣梭子蟹蜕皮的发生和进行。     

An Optimized Analytical Method for the Simultaneous Detection of Iodoform,Iodoacetic Acid,and Other Trihalomethanes and Haloacetic Acids in Drinking Water

An optimized method is presented using liquid-liquid extraction and derivatization for the extraction of iodoacetic acid (IAA) and other haloacetic acids (HAA₉) and direct extraction of iodoform (IF) and other trihalomethanes (THM₄) from drinking water, followed by detection by gas chromatography with electron capture detection (GC-ECD). A Doehlert experimental design was performed to determine the optimum conditions for the five most significant factors in the derivatization step: namely, the volume and concentration of acidic methanol (optimized values  = 15%, 1 mL), the volume and concentration of Na₂SO₄ solution (129 g/L, 8.5 mL), and the volume of saturated NaHCO₃ solution (1 mL). Also, derivatization time and temperature were optimized by a two-variable Doehlert design, resulting in the following optimized parameters: an extraction time of 11 minutes for IF and THM₄ and 14 minutes for IAA and HAA₉; mass of anhydrous Na₂SO₄ of 4 g for IF and THM₄ and 16 g for IAA and HAA₉; derivatization time of 160 min and temperature at 40°C. Under optimal conditions, the optimized procedure achieves excellent linearity (R² ranges 0.9990–0.9998), low detection limits (0.0008–0.2 µg/L), low quantification limits (0.008–0.4 µg/L), and good recovery (86.6%–106.3%). Intra- and inter-day precision were less than 8.9% and 8.8%, respectively. The method was validated by applying it to the analysis of raw, flocculated, settled, and finished waters collected from a water treatment plant in China.     

The Status of Vitamin B12 and Folate among Chinese Women: A Population-Based Cross-Sectional Study in Northwest China

Objective

To assess the status of the vitamin B12 and folate of Chinese women living in northwest China.

Methods

A population-based cross-sectional study was conducted in 2008 among Chinese women aged 10–49 years living in Shaanxi province of northwest China. A stratified multistage random sampling method was adopted to obtain a sample of 1170 women. The women were interviewed for collection of their background information and their plasma vitamin B12 and folate were measured with the immunoassay method. The status of both vitamins was evaluated and the prevalence of deficiency was estimated.

Results

The median value of the women was 214.5 pg/mL for vitamin B12 and 4.6 ng/mL for folate. The urban women had a significantly higher vitamin B12 (254.1 vs. 195.9 pg/mL) but lower folate (4.4 vs. 4.7 ng/mL) than rural women. Total prevalence of deficiency was 45.5% (95% CI: 42.6%∼48.4%) for vitamin B12 and 14.7% (95% CI: 12.6%∼16.8%) for folate. About 36% of women presented vitamin B12 deficiency alone, 5.2% belonged to folate deficiency alone and 9.5% was combined deficiency in both vitamins. More than 25% of the women were in marginal vitamin B12 status (200–299 pg/mL) and 60% in marginal status of folate (3–6 ng/mL). About 75.2% of rural women with folate deficiency were deficient in vitamin B12 and 46% for urban women. Quantile regression model found decreasing coefficient of folate status across 73 different quantiles of vitamin B12, which indicated that the women with folate deficiency had lower vitamin B12 significantly compared with those with no deficiency.

Conclusions

The deficiency of vitamin B12 and folate is still prevalent among the Chinese women in northwest China. Vitamin B12 deficiency could be more serious and the improvement of poor vitamin B12 status should be invoked when practicing the supplementation of folate against the neural tube defects in northwest China.     

Statin Treatment in Hypercholesterolemic Men Does Not Attenuate Angiotensin II-Induced Venoconstriction

Experimental studies suggested that statins attenuate vascular AT₁ receptor responsiveness. Moreover, the augmented excessive pressor response to systemic angiotensin II infusions in hypercholesterolemic patients was normalized with statin treatment. In 12 hypercholesterolemic patients, we tested the hypothesis that statin treatment attenuates angiotensin II-mediated vasoconstriction in hand veins assessed by a linear variable differential transducer. Subjects ingested daily doses of either atorvastatin (40 mg) or positive control irbesartan (150 mg) for 30 days in a randomized and cross-over fashion. Ang II–induced venoconstriction at minute 4 averaged 59%±10% before and 28%±9% after irbesartan (mean ± SEM; P<0.05) compared to 65%±11% before and 73%±11% after 30 days of atorvastatin treatment. Plasma angiotensin levels increased significantly after irbesartan treatment (Ang II: 17±22 before vs 52±40 pg/mL after [p = 0.048]; Ang-(1–7): 18±10 before vs 37±14 pg/mL after [p = 0.002]) compared to atorvastatin treatment (Ang II: 9±4 vs 11±10 pg/mL [p = 0.40]; Ang-(1–7): 24±9 vs 32±8 pg/mL [p = 0.023]). Our study suggests that statin treatment does not elicit major changes in angiotensin II-mediated venoconstriction or in circulating angiotensin II levels whereas angiotensin-(1–7) levels increased modestly. The discrepancy between local vascular and systemic angiotensin II responses might suggest that statin treatment interferes with blood pressure buffering reflexes.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00154024","term_id":"NCT00154024"}}NCT00154024     

Association between Human Urotensin II and Essential Hypertension—A 1:1 Matched Case-Control Study

Objective

We aimed to evaluate the controversial association between human urotensin II and essential hypertension in untreated hypertensive cases and normotensive controls.

Methods

197 newly diagnosed hypertensive patients and 197 age- and sex-matched normotensive controls were studied. Plasma urotensin II, nitric oxide metabolites, and other traditional biomarkers were examined.

Results

Hypertensive patients had higher urotensin II [median (interquartile rang): 9.32 (7.86–11.52) ng/mL vs 8.52 (7.07–10.41) ng/mL] and lower nitric oxide metabolites [19.19 (2.55–38.48) µmol/L vs 23.83 (11.97–43.40) µmol/L] than normotensive controls. Urotensin II was positively correlated with systolic blood pressure (r = 0.169, P<0.001) and diastolic blood pressure (r = 0.113, P = 0.024) while negatively correlated with nitric oxide metabolites (r = −0.112, P = 0.027). In multivariate regression analysis, subjects in the highest quartile of urotensin II were more likely to have hypertension than those in the lowest quartile (OR, 2.58; 95% CI, 1.21–5.49). Sub-group analyses in 106 pairs of cases and controls with either both normal or both abnormal nitric oxide metabolites levels showed that the association between urotensin II levels and hypertension persisted (P value for trend = 0.039).

Conclusion

Human urotensin II is markedly associated with essential hypertension, and the association is independent of nitric oxide metabolites. Our results indicated that urotensin II might be an independent risk factor for essential hypertension.     

Temporal Relationship between Vitamin D Status and Parathyroid Hormone in the United States

Background

Interpretation of parathyroid hormone (iPTH) requires knowledge of vitamin D status that is influenced by season.

Objective

Characterize the temporal relationship between 25-hydroxyvitamin D₃ levels [25(OH)D₃] and intact iPTH for several seasons, by gender and latitude in the U.S. and relate 25-hydrovitamin D₂ [25(OH)D₂] levels with PTH levels and total 25(OH)D levels.

Method

We retrospectively determined population weekly-mean concentrations of unpaired [25(OH)D₂ and 25(OH)D₃] and iPTH using 3.8 million laboratory results of adults. The 25(OH)D₃ and iPTH distributions were normalized and the means fit with a sinusoidal function for both gender and latitudes: North >40, Central 32–40 and South <32 degrees. We analyzed PTH and total 25(OH)D separately in samples with detectable 25(OH)D₂ (≥4 ng/mL).

Findings

Seasonal variation was observed for all genders and latitudes. 25(OH)D₃ peaks occurred in September and troughs in March. iPTH levels showed an inverted pattern of peaks and troughs relative to 25(OH)D₃, with a delay of 4 weeks. Vitamin D deficiency and insufficiency was common (33% <20 ng/mL; 60% <30 ng/mL) as was elevated iPTH levels (33%>65 pg/mL). The percentage of patients deficient in 25(OH)D₃ seasonally varied from 21% to 48% and the percentage with elevated iPTH reciprocally varied from 28% to 38%. Patients with detectable 25(OH)D₂ had higher PTH levels and 57% of the samples with a total 25(OH)D > 50 ng/mL had detectable 25(OH)D₂.

Interpretation

25(OH)D₃ and iPTH levels vary in a sinusoidal pattern throughout the year, even in vitamin D₂ treated patients; 25(OH)D₃, being higher in the summer and lower in the winter months, with iPTH showing the reverse pattern. A large percentage of the tested population showed vitamin D deficiency and secondary hyperparathyroidism. These observations held across three latitudinal regions, both genders, multiple-years, and in the presence or absence of detectable 25(OH)D₂, and thus are applicable for patient care.