Chronic treatment with statins increases the availability of selenium in the antioxidant defence systems of hemodialysis patients

ProjectOxidative stress (OS) is enhanced in hemodialysis (HD) patients. Lipid peroxidation and oxidative damage to glycids, proteins and nucleic acids are the main consequences of OS and are associated with increased cardiovascular risk. Vitamin E and glutathione peroxidase (GSH-Px) represent the main antioxidant systems in human cells. Selenium (Se), bound to the active sites of GSH-Pxs, plays a critical role in this antioxidant defence system. Statins are widely used and extensively investigated in the prevention of cardiovascular disease, notably in high-risk subjects. Several studies show antioxidant effects of statins not related to their lipid-lowering action. Our study aimed to compare serum Se concentration in ESRD patients on maintenance HD and in homogeneous healthy subjects and to investigate whether chronic treatment with statins may interfere with serum Se concentration in HD patients.ProcedureA total of 103 HD patients and 69 healthy subjects were enrolled; HD patients were divided into patients who were not treated with statins (group A) and patients who assumed statins since 6 months at least (group B). Serum Se was determined by atomic absorption spectrometry.ResultsSerum Se was significantly lower in HD patients of group A compared with healthy subjects (81.65±19.66 Vs. 96.47±15.62 mcg/L, p<0.0040). However, in HD patients who assumed statins serum, Se was significantly higher than in HD patients who did not (111.83±18.82 vs. 81.65±19.66 mcg/L, p<0.0001).ConclusionsOur results suggest that in HD patients chronic treatment with statins is related to higher-serum Se concentration.     

YKL-40 in patients with end-stage renal disease receiving haemodialysis

Purpose: This study aimed to determine serum YKL-40 in patients with end-stage renal disease (ESRD) on haemodialysis (HD) and to evaluate the prognostic value of serum YKL-40.

Methods: Patients >18?years on maintenance HD were included. Serum YKL-40 was measured using ELISA before and after a single HD treatment.

Results: A total of 306 patients were included. Median serum YKL-40 concentration was 238?µgL^?1 (IQR: 193–291?µgL^?1) before HD treatment and 198?µgL^?1 (IQR: 147–258?µgL^?1) after HD treatment, which corresponded to age-corrected 93th percentile in healthy subjects. All-cause mortality after 2.8?years was 35.9%. Patients with serum YKL-40 in the highest quartile compared with the lowest quartile had a univariate HR of 4.0 (95% CI: 2.2–7.3, p?p?=?0.01) in multivariate analysis. Time-dependent receiver operating characteristic curves showed that serum YKL-40 after HD treatment had significant higher area under the curves from 90?d (p?=?0.004) and throughout the rest of the follow-up period when compared to serum YKL-40 before HD treatment.

Conclusion: YKL-40 was highly elevated in patients with ESRD on HD, and dialysis reduced serum YKL-40 concentrations approximately one-sixth. YKL-40 measured after dialysis was independently associated with mortality in HD patients.     

The Growth Attainment,Hematological, Iron Status and Inflammatory Profile of Guatemalan Juvenile End-Stage Renal Disease Patients

BackgroundStunting, anemia and inflammation are frequently observed in children with end-stage renal disease (ESRD).ObjectivesTo assess anthropometric, hematological and inflammatory data and to study their potential interrelationship in Guatemalan juveniles undergoing hemodialysis (HD) and peritoneal dialysis (PD).Methods54 juveniles 7–20 years of age were recruited in FUNDANIER, Guatemala City: 27 on HD and 27 PD. Hemoglobin, serum iron, transferrin, serum transferrin receptor (sTfR), serum ferritin, transferrin saturation and iron-binding capacity, white blood cell count (WBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), as well as IL-6, IL-1 and TNF-α, weight and height were determined by standard methods. Hepcidin–25 (Hep-25) was assessed by weak cation exchange time-of-flight mass-spectrometry.Results92% and 55% of HD and PD children, respectively, were stunted and 95% and 85% were anemic. Among iron status biomarkers, serum ferritin was massively increased and significantly higher in the HD group compared to the PD group. Hep-25 was also greatly elevated in both groups. 41% of HD patients showed increments in three or more inflammatory biomarkers, while it was 2 or less in all PD subjects.ConclusionsThe degree of stunting, the prevalence and severity of anemia in Guatemalan juvenile ESRD far exceed the national statistics for this low-income Central American country. Ferritin and Hep-25 concentrations were elevated, with the latter to an extraordinary magnitude. Additional biomarkers of inflammation not directly related to iron status were elevated as well. The role of both disease- and environment-related factors in combination best explains the magnitude of the biomarker abnormalities.     

Factors Affecting Cerebral Oxygenation in Hemodialysis Patients: Cerebral Oxygenation Associates with pH,Hemodialysis Duration,Serum Albumin Concentration,and Diabetes Mellitus

BackgroundPatients undergoing hemodialysis (HD) often develop cerebral disease complications. Furthermore, cerebral regional saturation of oxygen (rSO₂) was previously reported to be significantly lower in HD patients than in healthy subjects. We aimed to identify the factors affecting the cerebral rSO₂ in HD patients.MethodsFifty-four HD patients (38 men and 16 women; mean age, 67.7 ± 1.2 years, HD duration, 6.5 ± 1.9 years) were recruited. Cerebral rSO₂ was monitored at the forehead before HD using an INVOS 5100C (Covidien Japan, Tokyo, Japan).ResultsThe rSO₂ levels were significantly lower in HD patients compared with healthy controls (49.5 ± 1.7% vs. 68.9 ± 1.6%, p <0.001). Multiple regression analysis showed that cerebral rSO₂ independently associated with pH (standardized coefficient: -0.35), HD duration (standardized coefficient: -0.33), and serum albumin concentration (standardized coefficient: 0.28). Furthermore, the rSO₂ was significantly lower in HD patients with diabetes mellitus (DM), compared with patients without DM (46.8 ± 1.7% vs. 52.1 ± 1.8%, p <0.05).ConclusionsIn HD patients, cerebral rSO₂ was affected by multiple factors, including pH, HD duration, and serum albumin concentration. Furthermore, this is the first report describing significantly lower levels of rSO₂ in HD patients with DM than in those without DM.     

Urgent-Start Peritoneal Dialysis and Hemodialysis in ESRD Patients: Complications and Outcomes

BackgroundSeveral studies have suggested that urgent-start peritoneal dialysis (PD) is a feasible alternative to hemodialysis (HD) in patients with end-stage renal disease (ESRD), but the impact of the dialysis modality on outcome, especially on short-term complications, in urgent-start dialysis has not been directly evaluated. The aim of the current study was to compare the complications and outcomes of PD and HD in urgent-start dialysis ESRD patients.MethodsIn this retrospective study, ESRD patients who initiated dialysis urgently without a pre-established functional vascular access or PD catheter at a single center from January 2013 to December 2014 were included. Patients were grouped according to their dialysis modality (PD and HD). Each patient was followed for at least 30 days after catheter insertion (until January 2016). Dialysis-related complications and patient survival were compared between the two groups.ResultsOur study enrolled 178 patients (56.2% male), of whom 96 and 82 patients were in the PD and HD groups, respectively. Compared with HD patients, PD patients had more cardiovascular disease, less heart failure, higher levels of serum potassium, hemoglobin, serum albumin, serum pre-albumin, and lower levels of brain natriuretic peptide. There were no significant differences in gender, age, use of steroids, early referral to a nephrologist, prevalence of primary renal diseases, prevalence of co-morbidities, and other laboratory characteristics between the groups. The incidence of dialysis-related complications during the first 30 days was significantly higher in HD than PD patients. HD patients had a significantly higher probability of bacteremia compared to PD patients. HD was an independent predictor of short-term (30-day) dialysis-related complications. There was no significant difference between PD and HD patients with respect to patient survival rate.ConclusionIn an experienced center, PD is a safe and feasible dialysis alternative to HD for ESRD patients with an urgent need for dialysis.     

Alteration of plasma total F2-isoprostanes before and after hemodialysis in end-stage renal disease patients

F(2)-isoprostanes are derived in vivo principally from the following: (1) the formation of positional peroxyl radicals of arachidonic acid, (2) endocyclization to prostaglandin G(2)-like structures, and (3) reduction to PGF(2)-like compounds. F(2)-isoprostanes have been proposed as biomarkers of lipid peroxidation, oxidative stress status, and the oxidation of low-density lipoprotein (LDL). Using gas chromatography-ion trap-mass spectrometry, we studied how hemodialysis (HD) affects plasma total F(2)-isoprostanes. We examined the plasma total F(2)-isoprostanes in end-stage renal disease (ESRD) patients, before HD, after HD, between HD, and in control subjects. Plasma concentrations of total F(2)-isoprostanes were significantly higher in the after HD ESRD patients than the before hemodialysis ESRD patients (P < 0.05). There is no difference between before HD ESRD patients and normal controls. Moreover, a positive or negative correlation was seen between LDL and plasma total F(2)-isoprostanes (P < 0.001), and between age and plasma total F(2)-isoprostanes (P < 0.001). This study indicates HD treatment may be the major contributor of oxidative stress in ESRD patients.     

Methylated arginines and nitric oxide in end-stage renal disease: impact of inflammation,oxidative stress and haemodialysis

Abstract

Objectives: To determine whether inflammation (C-reactive protein, CRP), oxidative stress (malondialdehyde, MDA) or haemodialysis (HD) affect associations between asymmetric (ADMA), symmetric (SDMA) dimethylarginine, NG-monomethyl-L-arginine (L-NMMA) and nitrite/nitrate (NOx) in end-stage renal disease (ESRD).

Method: Metabolites were measured pre-HD, after 1 hour and end-HD in 40 ESRD patients (age 63?±?14 years).

Results: Positive associations between NOx and ADMA (p?=?0.04), SDMA (p?<?0.001) and L-NMMA (p?=?0.04) were observed pre-HD. Associations weakened during HD but were not significantly influenced by CRP or MDA.

Conclusions: HD, oxidative stress or inflammation did not significantly affect the positive associations between methylated arginines and NOx in ESRD.     

腹膜透析和血液透析对终末期肾脏疾病患者钙磷代谢及微炎症状态的影响

目的:探讨腹膜透析(PD)和血液透析(HD)对终末期肾脏疾病(ESRD)患者钙磷代谢及微炎症状态的影响。方法:选择2016年1月~2017年2月我院收治的ESRD患者94例为研究对象,采用随机数字表法分为PD组(47例)和HD组(47例),PD组给予非卧床持续性PD治疗,HD组给予HD治疗,治疗6个月后比较两组血清钙磷代谢水平和微炎症状态,并统计两组并发症的发生率。结果:治疗6个月后,两组血清钙水平与治疗前相比显著升高,血清磷水平显著降低(P0.05),但HD组与PD组比较无差异(P0.05);治疗6个月后,两组血清C-反应蛋白(CRP)水平较治疗前明显升高,且HD组高于PD组,差异有统计学意义(P0.05),治疗6个月后,两组降钙素原(PCT)水平与治疗前相比显著降低,差异有统计学意义(P0.05),但HD组与PD组比较无差异(P0.05);PD组感染、低蛋白血症的发生率高于HD组,HD组高血压、心律失常、充血性心衰的发生率高于PD组,差异均有统计学意义(P0.05)。结论:PD和HD治疗均可改善ESRD患者钙磷代谢紊乱,但两者都将加剧患者微炎症反应,其中HD对患者微炎症状态的影响更大。     

A quantitative study of the biotransformation of insulin-enhancing VO2+ compounds

Potentiometric (pH titrations) and spectroscopic (electron paramagnetic resonance) methods have been used to determine the thermodynamic stability constants of the various VO²⁺ complexes formed after the interaction of four insulin-enhancing vanadium compounds, [VO(6-mepic)₂], cis-[VO(pic)₂(H₂O)], [VO(acac)₂], and [VO(dhp)₂], where 6-mepic, pic, acac, and dhp indicate the deprotonated forms of 6-methylpicolinic acid, picolinic acid, acetylacetone, and 1,2-dimethyl-3-hydroxy-4(1H)-pyridinone, with high molecular mass [human serum apotransferrin (hTf) and human serum albumin (HSA)] and low molecular mass (lactate) components of blood serum. In particular, log β values for the formation of (VO)hTf (13.0 ± 0.5), (VO)₂hTf (25.5 ± 0.5), (VO)HSA (9.1 ± 1.0), (VO) ₂ ^d HSA (20.9 ± 1.0), cis-VO(dhp)₂(hTf) (25.5 ± 0.6), cis-VO(dhp)₂(HSA) (25.9 ± 0.6), (VO)hTf(lact) (14.5 ± 0.8), (VO)₂hTf(lact)₂ (28.5 ± 0.8), (VO)hTf(pic) (15.6 ± 0.8), and (VO)₂hTf(pic)₂ (30.4 ± 0.8) were determined. The values of the stability constants were used to compare the calculated composition of ternary and quinary systems with that recently proposed by some of us through electron paramagnetic resonance and density functional theory methods (Sanna et al. in Inorg. Chem. 49:174–187, 2010) and to predict the distribution of VO²⁺ ion in blood serum when one of the four insulin-enhancing vanadium compounds studied, [VO(carrier)₂], is administered.     

Serum vanadium concentrations in different sports modalities

AimsThe aim of this study was to compare serum vanadium (V) concentrations between athletes of different sports modalities and people who did not practise physical exercise regularly.MethodsOne hundred and twenty-one subjects divided into a control group (CG; n = 37; 1.75 ± 0.03 m; 79.45 ± 10.20 kg; 24.72 ± 6.06 years) and an athletes’ group (AG; n = 84; 1.77 ± 0.05 m; 66.34 ± 6.12 kg; 19.57 ± 1.95 years) participated in this research. AG were classified by sports modality: aerobic (AE; n = 26), anaerobic (ANA; n = 22); aerobic-anaerobic (AE-ANA; n = 36). Serum V concentrations were analysed by inductively coupled plasma mass spectrometry.ResultsAG showed higher V concentrations compared to CG (p < 0.01). AE obtained higher concentrations compared to ANA and AE-ANA (p < 0.05).ConclusionsPhysical training could increase serum V levels. Specifically, aerobic sports modalities could increase serum V levels to a greater extent than other sports modalities.     

An observational study on disturbed peripheral circadian rhythms in hemodialysis patients

The quality of life of hemodialysis (HD) patients is hampered by reduced nocturnal sleep quality and excessive daytime sleepiness. In addition to the sleep/wake cycle, levels of circadian biomarkers (e.g. melatonin) are disturbed in end-stage renal disease (ESRD). This suggests impaired circadian clock performance in HD patients, but the underlying mechanism is unknown. In this observational study, diurnal rhythms of sleep, serum melatonin and cortisol concentrations and clock gene mRNA expression are compared between HD patients (n?=?9) and healthy control subjects (n?=?9). In addition, the presence of circulating factors that might affect circadian rhythmicity is tested in vitro with cell culture experiments. Reduced sleep quality (median sleep onset latency [interquartile range] of 23.9 [17.3]?min for patients versus 5.0 [10] minutes for controls, p?<?0.01; mean (± SD) sleep efficiency 70.2?±?8.1% versus 82.9?±?10.9%, p?=?0.02 and mean awake minutes after sleep onset 104.8?±?27.9 versus 54.6?±?41.6 minutes, p?= 0.01) and increased daytime sleepiness (mean Epworth Sleepiness Score of 10.0?±?4.8 versus 3.9?±?2.0, p?<?0.01) were confirmed in HD patients. Reduced nocturnal melatonin concentrations (1 AM: 98.1 [122.9] pmol/L versus 12.5 [44.2] pmol/L, p?= 0.019; 5 AM: 114.0 [131.6] pmol/L versus 11.8 [86.8] pmol/L, p?= 0.031) and affected circadian control of cortisol rhythm and circadian expression of the clock gene REV-ERBα were found. HD patient serum had a higher capacity to synchronize cells in vitro, suggesting an accumulated level of clock resetting compounds in HD patients. These compounds were not cleared by hemodialysis treatment or related to frequently used medications. In conclusion, the abovementioned results strongly suggest a disturbance in circadian timekeeping in peripheral tissues of HD patients. Accumulation of clock resetting compounds possibly contributes to this. Future studies are needed for a better mechanistic understanding of the interaction between renal failure and perturbation of the circadian clock.     

Impaired Orthostatic Response in Patients With Type 2 Diabetes Mellitus After 48 Hours of Bed Rest

ObjectiveTo compare the effect of bed rest on orthostatic responses of patients with type 2 diabetes mellitus and nondiabetic control subjects.MethodsSix patients with type 2 diabetes and 6 nondiabetic control subjects underwent 48 hours of bed rest and 48 hours of ambulatory activity in randomized order. A 10-minute tilt test was conducted before and after each period of hospitalization, and cardiovascular responses to 80° head-up tilt were analyzed with use of a 2-factorial (study group and bed rest condition) analysis of variance design. We hypothesized that patients with diabetes would experience more severe changes in orthostatic response after bed rest.ResultsNo significant differences in orthostatic responses were observed before bed rest between control subjects and patients with diabetes. After bed rest, control subjects had a greater (P = .01) increase in heart rate during tilt in comparison with before bed rest (before versus after bed rest, 9 ± 4 versus 24 ± 7 beats/min) and maintained their blood pressure during tilt. After bed rest, patients with diabetes did not have a compensatory increase in heart rate and had a greater (P = .02) decline in systolic blood pressure during tilt in comparison with before bed rest (before versus after bed rest, -7 ± 10 versus -21 ± 11 mm Hg). Their arm and leg skin vasomotor responses (laser Doppler flowmetry) during tilt were not altered after bed rest and were similar to those in control subjects before and after bed rest.ConclusionCardiac neuropathy in patients with type 2 diabetes may prevent a compensatory heart rate response after bed rest deconditioning and result in a more severe orthostatic response. A greater decrease in blood pressure with upright tilt is evident after a relatively short period of bed rest. (Endocr Pract. 2009;15:104-110)     

The Association Between Severity of Vitamin D Deficiency and Hashimoto's Thyroiditis

ObjectiveThe relation between vitamin D and autoimmune disorders has long been investigated regarding the important roles of this hormone in immune regulation. We evaluated 25-hydroxyvitamin D (25OHD) status in subjects with Hashimoto’s thyroiditis (HT) and healthy controls.MethodsGroup-1 included 180 euthyroid patients (123 females/57 males) with HT who were on a stable dose of L-thyroxine (LT). A total of 180 sex-, age-, and body mass index (BMI)-matched euthyroid subjects with newly diagnosed HT were considered as Group-2, and 180 healthy volunteers were enrolled as controls (Group-3). All 540 subjects underwent thyroid ultrasound and were evaluated for serum 25OHD, anti-thyroid peroxidase (anti- TPO), and anti-thyroglobulin (anti-TG) levels.ResultsGroup-1 had the lowest 25OHD levels (11.4 ± 5.2 ng/mL) compared to newly diagnosed HT subjects (Group-2) (13.1 ± 5.9 ng/mL, P = .002) and to control subjects (15.4 ± 6.8 ng/mL, P<.001). Serum 25OHD levels directly correlated with thyroid volume (r = 0.145, P<.001) and inversely correlated with anti-TPO (r = -0.361, P<.001) and anti-TG levels (r = -0.335, P<.001). We determined that 48.3% of Group-1, 35% of Group-2, and 20.5% of controls had severe 25OHD deficiency (<10 ng/mL). Female chronic HT patients had the lowest serum 25OHD levels (10.3 ± 4.58 ng/mL), and male control subjects had the highest (19.3 ± 5.9 ng/mL, P<.001).ConclusionsWe demonstrated that serum 25OHD levels of HT patients were significantly lower than controls, and 25OHD deficiency severity correlated with duration of HT, thyroid volume, and antibody levels. These findings may suggest a potential role of 25OHD in development of HT and/or its progression to hypothyroidism. (Endocr Pract. 2013;19:479-484)     

Association between trace elements in serum from bipolar disorder and schizophrenia patients considering treatment effects

BackgroundImbalances in metal concentrations have been suggested to contribute to the pathophysiology of different brain disorders, such as bipolar disorder (BD) and schizophrenia (SCZ).ObjectivesThe aim of this exploratory study is to evaluate the association between the concentrations of macro/trace elements in serum from BD and SCZ patients considering the effects from different treatments.MethodsEleven subjects with SCZ, seven with BD treated with lithium (BDL) and eight subjects with BD treated with other medications except lithium (BDN) were recruited for the study, as well as eleven healthy controls (HC). Serum concentrations of eleven macro/trace elements (Se, Zn, Fe, K, Ca, Mg, P, Al, Cu, Mn, and Ni) were determined using inductively coupled plasma mass spectrometry (ICP-MS).ResultsSe and Zn concentrations were significantly lower for patients with SCZ and BD in comparison to HC by one-way ANOVA test. Moreover, serum concentrations for Fe were significantly higher (p < 0.05) in BDN (548 ± 92 μg L⁻¹) and SCZ (632 ± 279 μg L⁻¹) in comparison to HC (421 ± 121 μg L⁻¹). A significant negative correlation was reported between Se and Fe in BDL group (r = −0.935, p < 0.05). In addition, a significantly higher Cu/Zn ratio was determined in SCZ group against HC (ratio = 2.4, p = 0.028).ConclusionsThe obtained results suggest that the imbalance in Fe concentrations is an effect of BD treatment. Lithium is supposed to have an antagonist effect for Se in BDL patients. A negative correlation reported between Fe and BMI in SCZ group could be related to antipsychotic treatment and the Cu/Zn ratio reported could be considered as a suggesting parameter to relate oxidative stress to SCZ. Future studies including larger number of patients with SCZ and BD before and after treatment are necessary to confirm the investigative results presented herein.     

Spectroscopic evaluation of synthesized 5β-dihydrocortisol and 5β-dihydrocortisol acetate binding mechanism with human serum albumin and their role in anticancer activity

Our study focus on the biological importance of synthesized 5β-dihydrocortisol (Dhc) and 5β-dihydrocortisol acetate (DhcA) molecules, the cytotoxic study was performed on breast cancer cell line (MCF-7) normal human embryonic kidney cell line (HEK293), the IC₅₀ values for MCF-7 cells were 28 and 25 μM, respectively, whereas no toxicity in terms of cell viability was observed with HEK293 cell line. Further experiment proved that Dhc and DhcA induced 35.6 and 37.7% early apoptotic cells and 2.5, 2.9% late apoptotic cells, respectively, morphological observation of cell death through TUNEL assay revealed that Dhc and DhcA induced apoptosis in MCF-7 cells. The complexes of HSA–Dhc and HSA–DhcA were observed as static quenching, and the binding constants (K) was 4.7 ± .03 × 10⁴ M^?1 and 3.9 ± .05 × 10⁴ M^?1_, and their binding free energies were found to be ?6.4 and ?6.16 kcal/mol, respectively. The displacement studies confirmed that lidocaine 1.4 ± .05 × 10⁴ M^?1 replaced Dhc, and phenylbutazone 1.5 ± .05 × 10⁴ M^?1 replaced by DhcA, which explains domain I and domain II are the binding sites for Dhc and DhcA. Further, FT-IR, synchronous spectroscopy, and CD results revealed that the secondary structure of HSA was altered in the presence of Dhc and DhcA. Furthermore, the atomic force microscopy and transmission electron microscopy showed that the dimensions like height and molecular size of the HSA–Dhc and HSA–DhcA complex were larger compared to HSA alone. Detailed analysis through molecular dynamics simulations also supported greater stability of HSA–Dhc and HSA–DhcA complexes, and root-mean-square-fluctuation interpreted the binding site of Dhc as domain IB and domain IIA for DhcA. This information is valuable for further development of steroid derivative with improved pharmacological significance as novel anti-cancer drugs.     

Forskolin-loaded human serum albumin nanoparticles and its biological importance

Abstract

In this study, forskolin-loaded human serum albumin nanoparticles (FR-HSANPs) were successfully prepared by incorporation and affinity-binding methods. FR-HSANPs were characterized by transmission electron microscope that most of them are circular in shape and size is around 340?nm. The drug loading was more than 88% and further sustained release profiles were observed as it is 77.5% in 24?h time. Additionally, the cytotoxicity results with HepG2 cells indicated that FR-HSANPs showed significantly higher cytotoxicity and lower cell viability as compared to free forskolin (FR). Furthermore, to understand the binding mechanism of human serum albumin (HSA) with forskolin resulted from fluorescence quenching as a static mechanism and the binding constant is 6.26?±?0.1?×?10⁴ M^?1, indicating a strong binding affinity. Further, association and dissociation kinetics of forskolin–HSA was calculated from surface plasmon resonance spectroscopy and the binding constant found to be K_forskolin = 3.4?±?0.24?×?10⁴ M^?1 and also fast dissociation was observed. Further, we used circular dichroism and molecular dynamics simulations to elucidate the possible structural changes including local conformational changes and rigidity of the residues of both HSA and HSA–forskolin complexes.

Communicated by Ramaswamy H. Sarma     

Enrichment of cysteinyl adducts of human serum albumin

We report a method to enrich cysteinyl adducts of human serum albumin (HSA), representing biomarkers of exposure to systemic electrophiles. Because the major site of HSA adduction is the single free sulfhydryl group at Cys34, we used thiol-affinity resins to remove mercaptalbumin (i.e., unadducted HSA) from the cysteinyl adducts. Electrospray ionization mass spectrometry was used to detect mercaptalbumin and HSA-Cys34 modifications before and after enrichment of HSA. Differences in adduct content were detected across samples of freshly isolated, archived, and commercial HSA. Cysteinylated and glycosylated adducts were present in all samples, with abundances decreasing in the following order: commercial HSA > archived HSA > fresh HSA. After enrichment of HSA, mercaptalbumin was no longer observed in mass spectra. The ratios of HSA adducts post-/preenrichment, quantified via the Bradford assay and gel electrophoresis, were 0.029 mg adducts/mg HSA in fresh HSA and 0.323 mg adducts/mg HSA in archived HSA. The apparent elevation of adduct levels in archived samples could be due to differences in specimen preparation and storage rather than to differences in circulating HSA adducts. We conclude that thiol-affinity resins can efficiently remove mercaptalbumin from HSA samples prior to characterization and quantitation of protein adducts of reactive systemic electrophiles.     

Supramolecular interaction of 6-shogaol,a therapeutic agent of Zingiber officinale with human serum albumin as elucidated by spectroscopic,calorimetric and molecular docking methods

Background6-Shogaol, one of the main bioactive constituents of Zingiber officinale has been shown to possess various therapeutic properties. Interaction of a therapeutic compound with plasma proteins greatly affects its pharmacokinetic and pharmacodynamic properties.PurposeThe present investigation was undertaken to characterize the interaction between 6-shogaol and the main in vivo transporter, human serum albumin (HSA).MethodsVarious binding characteristics of 6-shogaol–HSA interaction were studied using fluorescence spectroscopy. Thermal stability of 6-shogaol–HSA system was determined by circular dichroism (CD) and differential scanning calorimetric (DSC) techniques. Identification of the 6-shogaol binding site on HSA was made by competitive drug displacement and molecular docking experiments.ResultsFluorescence quench titration results revealed the association constant, K_a of 6-shogaol–HSA interaction as 6.29 ± 0.33 × 10⁴ M⁻¹ at 25 ºC. Values of the enthalpy change (−11.76 kJ mol⁻¹) and the entropy change (52.52 J mol⁻¹ K⁻¹), obtained for the binding reaction suggested involvement of hydrophobic and van der Waals forces along with hydrogen bonds in the complex formation. Higher thermal stability of HSA was noticed in the presence of 6-shogaol, as revealed by DSC and thermal denaturation profiles. Competitive ligand displacement experiments along with molecular docking results suggested the binding preference of 6-shogaol for Sudlow's site I of HSA.ConclusionAll these results suggest that 6-shogaol binds to Sudlow's site I of HSA through moderate binding affinity and involves hydrophobic and van der Waals forces along with hydrogen bonds.     

Increased oxidative stress and altered serum macro-minerals and trace elements levels are associated with coronary artery disease

BackgroundThis study was designed to evaluate the serum malondialdehyde (MDA), non-enzymatic antioxidants (vitamin A and C), macro-minerals (magnesium and calcium), and trace elements (zinc, copper, and iron) levels in patients with coronary artery disease (CAD) and to explore their role in disease progression.MethodsThis prospective case-control study was comprised of 40 CAD patients and 40 healthy volunteers as cases and control subjects, respectively. The level of lipid peroxidation was assessed by measuring the serum MDA level using a UV spectrophotometer. The levels of vitamins A and C were determined by high-performance liquid chromatography (HPLC) and UV spectrophotometric method, respectively. Atomic absorption spectroscopy (AAS) was used to measure serum macro-minerals (Mg and Ca) and trace elements (Zn, Cu, and Fe) concentrations.ResultsThe mean age of CAD patients and control subjects was 53.90 ± 2.22 and 37.03 ± 1.50 years, respectively. This study revealed significantly higher concentrations of MDA (p < 0.01) and lower concentrations of vitamin A (p < 0.01), and vitamin C (p < 0.05) in the CAD patients than in control subjects. The mean values of Mg, Cu, Zn, Ca, and Fe were 11.67 ± 0.64, 1.17 ± 0.03, 0.43 ± 0.02, 107.38 ± 1.81, and 1.66 ± 0.04 μg/mL, respectively for the CAD patients and 19.38 ± 0.65, 1.07 ± 0.02, 0.87 ± 0.02, 94.29 ± 1.89, and 1.52 ± 0.05 μg/mL, respectively for the controls and the differences were significant (p < 0.05) between the patients and controls.ConclusionFrom these findings, we can suggest that there is a strong association of CAD with an elevated level of MDA, depleted levels of antioxidants, and altered macro-minerals and trace elements concentrations.     

Reduced Parathyroid Hormone-Stimulated 1,25-Dihydroxyvitamin D Production in Vitamin D Sufficient Postmenoposual Women with Low Bone Mass and Idiopathic Secondary Hyperparathyroidism

ObjectiveDistinguishing secondary hyperparathyroidism (sHPT) from eucalcemic primary hyperparathyroidism (EC-pHPT) is important. The objective of this study was to measure parathyroid hormone (PTH)-stimulated production of 1α,25-dihydroxyvitamin D (1,25[OH]₂D) in early postmenopausal patients with idiopathic sHPT, who also fit the criteria for EC-pHPT, compared to age-matched controls.MethodsIn this pilot case-control study, postmenopausal women aged 44 to 55 years with normal serum calcium (Ca), glomerular filtration rate (GFR) ≥65 mL/min, and 25-hydroxyvitamin D (25[OH]D) ≥75 nmol/L (30 ng/mL) were given an 8 hour infusion of PTH(1-34), 12 pmol/kg/h. Patients (n = 5) had elevated PTH, normal 1,25(OH)₂D, and no hypercalciuria. Controls (n = 5) had normal PTH. At baseline, 4, and 8 hours, serum Ca, creatinine (Cr), phosphorus (P), 1,25(OH)₂D, fibroblast growth factor (FGF23), and 24,25(OH)₂D as well as urine Ca, P, Cr, and cAMP/GFR were measured. The fractional excretion of calcium (FeCa) and tubular reabsorption of phosphorus (TMP)/GFR were calculated.ResultsPatients had lower 1,25(OH)₂D levels (± SD) than controls at 4 (39.8 ± 6.9 versus 58.8 ± 6.7; P = .002) and 8 hours (56.4 ± 9.2 versus 105 ± 2.3; P = .003) of PTH infusion, attenuated after adjusting for higher body mass index (BMI) in patients (P = .05, .04), respectively. The 24,25(OH)2D levels were lower in patients than controls (1.9 ± 0.6 versus 3.4 ± 0.6, respectively; P = .007). No differences were seen in serum Ca or P, urine cAMP/GFR, TRP/GFR, FeCa, or PTH suppression at 8 hours (patients 50%, controls 64%).ConclusionVitamin D sufficient patients who fit the criteria for EC-pHPT had reduced PTH-stimulated 1,25(OH)₂D compared to controls, partially attributable to their higher BMI. Other causes of reduced 1,25(OH)₂D production ruled out were excessive catabolism of vitamin D metabolites, elevated FGF23, and CYP27B1 mutation. Elevated BMI and idiopathic reduced PTH-stimulated 1,25(OH)₂D production should be considered in the differential of sHPT. (Endocr Pract. 2013;19:91-99)