Synthesis and electrochemical properties of environmental free l-glutathione grafted graphene oxide/ZnO nanocomposite for highly selective piroxicam sensing

A simple and reliable strategy was proposed to engineer the glutathione grafted graphene oxide/ZnO nanocomposite (glutathione-GO/ZnO) as electrode material for the high-performance piroxicam sensor. The prepared glutathione-GO/ZnO nanocomposite was well characterized by X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). The novel nanocomposite modified electrode showed the highest electrocatalytic activity towards piroxicam (oxidation potential is 0.52 V). Under controlled experimental parameters, the proposed sensor exhibited good linear responses to piroxicam concentrations ranging from 0.1 to 500 μM. The detection limit and sensitivity were calculated as 1.8 nM and 0.2 μA/μM·cm², respectively. Moreover, it offered excellent selectivity, reproducibility, and long-term stability and can effectively ignore the interfering candidates commonly existing in the pharmaceutical tablets and human fluids even at a higher concentration. Finally, the reported sensor was successfully employed to the direct determination of piroxicam in practical samples.     

Simultaneous enantioseparation and simulation studies of atenolol,metoprolol and propranolol on Chiralpak® IG column using supercritical fluid chromatography

Enantioseparation of three β-blockers, i.e., atenolol, metoprolol and propranolol, was studied on amylose tris(3-chloro-5-methylphenylcarbamate) immobilized chiral stationary phase using supercritical fluid chromatography (SFC). The effect of organic modifiers (methanol, isopropanol and their mixture), column temperature and back pressure on chiral separation of β-blockers was evaluated. Optimum chromatographic separation with respect to resolution, retention, and analysis time was achieved using a mixture of CO₂ and 0.1% isopropyl amine in isopropanol: methanol (50:50, V/V), in 75:25 (V/V) ratio. Under the optimized conditions, the resolution factors (R_s) and separation factors (α) were greater than 3.0 and 1.5, respectively. Further, with increase in temperature (25–45 °C) and pressure (100–150 bars) there was corresponding decrease in retention factors (k), α and R_s. However, a reverse trend (α and R_s) was observed for atenolol with increase in temperature. The thermodynamic data from van''t Hoff plots revealed that the enantioseparation was enthalpy driven for metoprolol and propranolol while entropy driven for atenolol. To understand the mechanism of chiral recognition and the elution behavior of the enantiomers, molecular docking studies were performed. The binding energies obtained from simulation studies were in good agreement with the elution order found experimentally and also with the free energy values. The method was validated in the concentration range of 0.5–10 μg/mL for all the enantiomers. The limit of detection and limit of quantitation ranged from 0.126 to 0.137 μg/mL and 0.376–0.414 μg/mL, respectively. The method was used successfully to analyze these drugs in pharmaceutical preparations.     

Overoxidized poly(3,4-ethylenedioxythiophene)–gold nanoparticles–graphene-modified electrode for the simultaneous detection of dopamine and uric acid in the presence of ascorbic acid

An innovative, ternary nanocomposite composed of overoxidized poly(3,4-ethylenedioxythiophene) (OPEDOT), gold nanoparticles (AuNPs), and electrochemically reduced graphene oxide (ERGO) was prepared on a glassy carbon electrode (GCE) (OPEDOT–AuNPs–ERGO/GCE) through homogeneous chemical reactions and heterogeneous electrochemical methods. The morphology, composition, and structure of this nanocomposite were characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The electrochemical properties of the OPEDOT–AuNPs–ERGO/GCE were investigated by cyclic voltammetry using potassium ferricyanide and hexaammineruthenium(III) chloride redox probe systems. This modified electrode shows excellent electro-catalytic activity for dopamine (DA) and uric acid (UA) under physiological pH conditions, but inhibits the oxidation of ascorbic acid (AA). Linear voltammetric responses were obtained when DA concentrations of approximately 4.0–100 μM and UA concentrations of approximately 20–100 μM were used. The detection limits (S/N=3) for DA and UA were 1.0 and 5.0 μM, respectively, under physiological conditions and in the presence of 1.0 mM of AA. This developed method was applied to the simultaneous detection of DA and UA in human urine, where satisfactory recoveries from 96.7% to 105.0% were observed. This work demonstrates that the developed OPEDOT–AuNPs–ERGO ternary nanocomposite, with its excellent ion-selectivity and electro-catalytic activity, is a promising candidate for the simultaneous detection of DA and UA in the presence of AA in physiological and pathological studies.     

An ionic liquid supported CeO2 nanoparticles–carbon nanotubes composite-enhanced electrochemical DNA-based sensor for the detection of Pb2+

An electrochemical sensor incorporating a signal enhancement for the determination of lead (II) ions (Pb²⁺) was designed on the basis of the thrombin-binding aptamer (TBA) as a molecular recognition element and ionic liquid supported cerium oxide (CeO₂) nanoparticles–carbon nanotubes composite modification. The composite comprises nanoparticles CeO₂, multi-wall carbon nanotubes (MWNTs) and hydrophobic room temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF₄). The electrochemical sensors were fabricated by immersing the CeO₂–MWNTs–EMIMBF₄ modified glassy carbon electrode (GCE) into the solution of TBA probe. In the presence of Pb²⁺, the TBA probe could form stable G-quartet structure by the specific binding interactions between Pb²⁺ and TBA. The TBA-bound Pb²⁺ can be electrochemically reduced, which provides a readout signal for quantitative detection of Pb²⁺. The reduction peak current is linearly related to the concentration of Pb²⁺ from 1.0×10^–8 M to 1.0×10^–5 M with a detection limit of 5×10^–9 M. This work demonstrates that the CeO₂–MWNTs–EMIMBF₄ nanocomposite modified GCE provides a promising platform for immobilizing the TBA probe and enhancing the sensitivity of the DNA-based sensors.     

Heterogeneous vancomycin-intermediate among methicillin resistant Staphylococcus aureus

Background

Hetero-resistance vancomycin intermediate Staphylococcus aureus (hVISA) is phenotype, which on in-vitro susceptibility test is vancomycin susceptible (VSSA) but has a minority population of vancomycin intermediate (VISA). hVISA is responsible for vancomycin treatment failure. Population Analysis Profile- Area under Curve (PAP-AUC) is a test for detection of hVISA; however, this test is unsuitable for clinical microbiology laboratory. Tests, such as Brain Heart Infusion Agar with 6 μg/ml vancomycin (BHIA6V), E test and Macromethod E Test (MET) are available; however reported to have variable results.

Methods

58 clinical isolates of Methicillin resistant S aureus (MRSA) having MIC of vancomycin more than 1 μg/ml by E test and agar dilution were analyzed by PAP-AUC, BHIA6V and MET.

Result

The prevalence of hVISA was 6.9%. hVISA isolates were having vancomycin E test MIC >2 μg/ml. Sensitivity of BHIA6V, MET and E test with MIC >2 μg/ml were 0.75, 0.67 and 1.0 respectively; however, positive predictive values (PPV) were 0.43, 0.4 and 0.27 respectively with PAP-AUC. PAP-AUC ratio correlated with MIC by E test and MET.

Conclusions

There is need for screening MRSA isolates showing in-vitro vancomycin susceptibility ≤2 μg/ml by agar dilution method for detection of hVISA. PAP-AUC test is unsuitable for routine laboratory testing. BHIA6V, MET and E test can be used for screening, however have low PPV.     

Carbon dots derived from Poria cocos polysaccharide as an effective “on-off” fluorescence sensor for chromium (VI) detection

Chromium is a harmful contaminant showing mutagenicity and carcinogenicity. Therefore, detection of chromium requires the development of low-cost and high-sensitivity sensors. Herein, blue-fluorescent carbon quantum dots were synthesized by one-step hydrothermal method from alkali-soluble Poria cocos polysaccharide, which is green source, cheap and easy to obtain, and has no pharmacological activity due to low water solubility. These carbon quantum dots exhibit good fluorescence stability, water solubility, anti-interference and low cytotoxicity, and can be specifically combined with the detection of Cr(VI) to form a non-fluorescent complex that causes fluorescence quenching, so they can be used as a label-free nanosensor. High-sensitivity detection of Cr(VI) was achieved through internal filtering and static quenching effects. The fluorescence quenching degree of carbon dots fluorescent probe showed a good linear relationship with Cr(VI) concentration in the range of 1–100 μM. The linear equation was F₀/F = 0.9942 + 0.01472 [Cr(VI)] (R² = 0.9922), and the detection limit can be as low as 0.25 μM (S/N = 3), which has been successfully applied to Cr(VI) detection in actual water samples herein.     

Synergy of drug combinations in treating multidrug-resistant Pseudomonas aeruginosa

Background

With the emergence of metallo-betalactamases (MBL) in Pseudomonas aeruginosa (P. aeruginosa), the value of carbapenem, the drug of last resort, is being severely compromised. Curtailing the use of carbapenems becomes paramount if resistance is to be reined in.

Aims

To study the role of synergy between combinations of drugs as an alternative treatment choice for P. aeruginosa. Synergy was studied between combinations of levofloxacin with piperacillin-tazobactam and levofloxacin with cefoperazone-sulbactam by time-kill and chequerboard techniques.

Methods

P. aeruginosa were tested for antibiotic susceptibility by the disc diffusion assay (260 isolates) and E-test (60 isolates). Synergy testing by chequerboard and time-kill assays was performed with combinations of piperacillin-tazobactam with levofloxacin (11 isolates) and cefoperazone-sulbactam with levofloxacin (10 isolates).

Results

Nearly all isolates were susceptible to piperacillin-tazobactam (96.1 per cent), followed by piperacillin (78.5 per cent). Seventy-one isolates (27.3 per cent) were found to be multidrug resistant and 19.6 per cent were ESBL producers. MIC₅₀ of amikacin was 32μg/ml and MIC₉₀ was 64μg/ml. MIC₅₀ and MIC₉₀ of cefoperazone-sulbactam was 32μg/ml and 64μg/ml, and for levofloxacin it was 10μg/ml and 240μg/ml, respectively. Piperacillin-tazobactam had MIC₅₀ and MIC₉₀ of 5μg/ml and 10μg/ml, respectively. Synergy was noted in 72.7 per cent isolates for levofloxacin and piperacillin-tazobactam combination, the remaining 27.3 per cent isolates showed addition by both chequerboard and time-kill assay. For levofloxacin and cefoperazone-sulbactam, only 30 per cent isolates had synergy, 40 per cent showed addition, 20 per cent indifference, and 10 per cent were antagonistic by the chequerboard method.

Conclusion

The combination of levofloxacin and piperacillin-tazobactam is a good choice for treatment of such strains.     

Triptolide ameliorates lipopolysaccharide-induced acute lung injury in rats

Background

Acute lung injury (ALI) is a serious clinical syndrome with a high rate of mortality. In this study, the effects of triptolide on lipopolysaccharide (LPS)-induced ALI in rats were investigated.

Methods

Sixty-five male Sprague Dawley rats(approved by ethics committee of the First Affiliated Hospital of Soochow University) were randomly divided into five groups. The control group was injected with 2.5 mL saline/kg body weight via the tail vein and intraperitoneally with 1% dimethyl sulfoxide (DMSO) (n = 5). The L group was administered with 0.2% LPS dissolved in saline (5 mg/kg) to induce ALI via the tail vein (n = 15). The TP1, TP2, and TP3 groups were treated as rats in the L group and then intraperitoneally injected with 25, 50, and 100 μg triptolide/kg body weight, respectively (15 rats per group). Blood samples from the left heart artery were taken for blood gas analysis at 1 hour before injection and at 1, 3, 6, and 12 hours after saline and DMSO administration in the control group, LPS injection in the L group, and triptolide injection in the TP1, TP2, and TP3 groups. Lung wet-to-dry weight (W/D) ratio, diffuse alveolar damage (DAD) score, TNF-α levels, and mRNA and protein expression of toll-like receptor 4 (TLR4) were analyzed.

Results

Compared with the control group, the arterial partial pressure of oxygen (PaO₂) declined (P <0.05), the W/D ratio and DAD score increased (P <0.05), and TNF-α levels in serum and bronchoalveolar lavage fluid (BALF) and mRNA and protein expression of TLR4 were significantly increased in the L group (P <0.05). Compared with the L group, PaO₂ significantly increased in the TP2 and TP3 groups (P <0.05), while the W/D ratio and DAD score were significantly decreased in the TP2 and TP3 groups (P <0.05). TNF-α levels and mRNA and protein expression of TLR4 were significantly decreased in the TP2 and TP3 groups compared with the L group (P <0.05).

Conclusions

Triptolide can ameliorate LPS-induced ALI by reducing the release of the inflammatory mediator TNF-α and inhibiting TLR4 expression.     

Effect of insulin-induced hypoglycemia on the serum concentrations of thyroxine, triiodothyronine and reverse triiodothyronine

The effect of insulin-induced hypoglycemia on serum thyroid hormone concentrations was studied in nine healthy individuals. Before, during and after the hypoglycemia blood samples were taken for measurement of the concentrations of glucose, thyroxine (T₄), triiodothyronine (T₃), reverse triiodothyronine (rT₃), catecholamines and pituitary hormones.

There was no change in the mean serum T₄ level (± the standard error of the mean) of 67 ± 2 μg/l. However, the T₃ concentrations rose from a mean basal level of 1.86 ± 0.06 μg/l to a mean peak of 2.51 ± 0.21 μg/l (P < 0.01) at 45 minutes after the insulin injection, and the rT₃ concentrations fell from a mean basal level of 0.184 ± 0.008 μg/l to a mean nadir of 0.171 ± 0.022 μg/l (not a significant change). The mean peak epinephrine level was 545 ± 103 ng/l and it occurred between 30 and 45 minutes after the insulin injection; the mean peak norepinephrine level was 584 ± 114 ng/l and it occurred between 30 and 90 minutes after the injection. The growth hormone levels reached a mean peak of 26.1 ± 4.8 μg/l and the plasma cortisol levels rose to 215 ± 9 μg/l. The mean basal prolactin level was 8.5 ± 0.9 μg/l; in five subjects there was a rise to a mean peak of 50.6 ± 14.6 μg/l, whereas in the remaining four no significant increase occurred. No correlation was found between the changes in the serum T₃ concentration and any of the other factors studied.

It was concluded that acute hypoglycemia is associated with a rapid increase in the serum T₃ concentration.

     

Highly sensitive electrochemical determination of rutin based on the synergistic effect of 3D porous carbon and cobalt tungstate nanosheets

Rutin, a flavonoid found in fruits and vegetables, is a potential anticancer compound with strong anticancer activity. Therefore, electrochemical sensor was developed for the detection of rutin. In this study, CoWO₄ nanosheets were synthesized via a hydrothermal method, and porous carbon (PC) was prepared via high-temperature pyrolysis. Successful preparation of the materials was confirmed, and characterization was performed by transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. A mixture of PC and CoWO₄ nanosheets was used as an electrode modifier to fabricate the electrochemical sensor for the electrochemical determination of rutin. The 3D CoWO₄ nanosheets exhibited high electrocatalytic activity and good stability. PC has a high surface-to-volume ratio and superior conductivity. Moreover, the hydrophobicity of PC allows large amounts of rutin to be adsorbed, thereby increasing the concentration of rutin at the electrode surface. Owing to the synergistic effect of the 3D CoWO₄ nanosheets and PC, the developed electrochemical sensor was employed to quantitively determine rutin with high stability and sensitivity. The sensor showed a good linear range (5–5000 ng/mL) with a detection limit of 0.45 ng/mL. The developed sensor was successfully applied to the determination of rutin in crushed tablets and human serum samples.     

Relative Bioavailability of Rifampicin in Four Chinese Fixed-dose Combinations Compared with Rifampicin in Free Combinations

Background:

Decreases in the bioavailability of rifampicin (RFP) can lead to the development of drug resistance and treatment failure. Therefore, we investigated the relative bioavailability of RFP from one four-drug fixed-dose combination (FDC; formulation A) and three two-drug FDCs (formulations B, C, and D) used in China, compared with RFP in free combinations of these drugs (reference), in healthy volunteers.

Methods:

Eighteen and twenty healthy Chinese male volunteers participated in two open-label, randomized two-period crossover (formulations A and C) or one three-period crossover (formulations B and D) study, respectively. The washout period between treatments was 7 days. Bioequivalence was assessed based on 90% confidence intervals, according to two one-sided t-tests. All analyses were done with DAS 3.1.5 (Mathematical Pharmacology Professional Committee of China, Shanghai, China).

Results:

Mean pharmacokinetic parameter values of RFP obtained for formulations A, B, C, and D products were 11.42 ± 3.41 μg/ml, 7.86 ± 5.78 μg/ml, 13.05 ± 6.80 μg/ml, and 16.18 ± 3.87 μg/ml, respectively, for peak plasma concentration (C_max), 91.43 ± 30.82 μg·h⁻¹ ·ml⁻¹, 55.49 ± 37.58 μg·h⁻¹ ·ml⁻¹, 96.50 ± 47.24 μg·h⁻¹ ·ml⁻¹, 101.47 ± 33.07 μg·h⁻¹ ·ml⁻¹, respectively, for area under the concentration-time curve (AUC_{0−24 h}).

Conclusions:

Although the concentrations of RFP for formulations A, C, and D were within the reported acceptable therapeutic range, only formulation A was bioequivalent to the reference product. The three two-drug FDCs (formulations B, C and D) displayed inferior RFP bioavailability compared with the reference (Chinese Clinical Trials registration number: ChiCTR-TTRCC-12002451).     

Bi2O3/ZnO nanocomposite: Synthesis,characterizations and its application in electrochemical detection of balofloxacin as an anti-biotic drug

In the present work, a chemically modified electrode has been fabricated utilizing Bi₂O₃/ZnO nanocomposite. The nanocomposite was synthesized by simple sonochemical method and characterized for its structural and morphological properties by using XRD, FESEM, EDAX, HRTEM and XPS techniques. The results clearly indicated co-existence of Bi₂O₃ and ZnO in the nanocomposite with chemical interaction between them. Bi₂O₃/ZnO nanocomposite based glassy carbon electrode (GCE) was utilized for sensitive voltammetric detection of an anti-biotic drug (balofloxacin). The modification amplified the electroactive surface area of the sensor, thus providing more sites for oxidation of analyte. Cyclic and square wave voltammograms revealed that Bi₂O₃/ZnO modified electrode provides excellent electrocatalytic action towards balofloxacin oxidation. The current exhibited a wide linear response in concentration range of 150–1000 nM and detection limit of 40.5 nM was attained. The modified electrode offered advantages in terms of simplicity of preparation, fair stability (RSD 1.45%), appreciable reproducibility (RSD 2.03%) and selectivity. The proposed sensor was applied for determining balofloxacin in commercial pharmaceutical formulations and blood serum samples with the mean recoveries of 99.09% and 99.5%, respectively.     

Salvianolic Acid B Down-regulates Matrix Metalloproteinase-9 Activity and Expression in Tumor Necrosis Factor-α-induced Human Coronary Artery Endothelial Cells

Background:

Salvianolic acid B (Sal B) is a bioactive water-soluble compound of Salviae miltiorrhizae, a traditional herbal medicine that has been used clinically for the treatment of cardiovascular diseases. This study sought to evaluate the effect of Sal B on matrix metalloproteinase-9 (MMP-9) and on the underlying mechanisms in tumor necrosis factor-α (TNF-α)-activated human coronary artery endothelial cells (HCAECs), a cell model of Kawasaki disease.

Methods:

HCAECs were pretreated with 1–10 μmol/L of Sal B, and then stimulated by TNF-α at different time points. The protein expression and activity of MMP-9 were determined by Western blot assay and gelatin zymogram assay, respectively. Nuclear factor-κB (NF-κB) activation was detected with immunofluorescence, electrophoretic mobility shift assay, and Western blot assay. Protein expression levels of mitogen-activated protein kinase (c-Jun N-terminal kinase [JNK], extra-cellular signal-regulated kinase [ERK], and p38) were determined by Western blot assay.

Results:

After HCAECs were exposed to TNF-α, 1–10 μmol/L Sal B significantly inhibited TNF-α-induced MMP-9 expression and activity. Furthermore, Sal B significantly decreased IκBα phosphorylation and p65 nuclear translocation in HCAECs stimulated with TNF-α for 30 min. In addition, Sal B decreased the phosphorylation of JNK and ERK1/2 proteins in cells treated with TNF-α for 10 min.

Conclusions:

The data suggested that Sal B suppressed TNF-α-induced MMP-9 expression and activity by blocking the activation of NF-κB, JNK, and ERK1/2 signaling pathways.     

In?vitro vancomycin susceptibility amongst methicillin resistant Staphylococcus aureus

Background

Vancomycin is drug of choice for treatment of Methicillin Resistant Staphylococcus aureus (MRSA) infections. S. aureus with reduced vancomycin susceptibility (SA-RVS) is on rise. Current guidelines of detection of SA-RVS are based on MIC (Minimum Inhibitory Concentration) by broth or agar dilution methods. Vancomycin MIC by E test (Epsilometer Test) is an alternative. A study was undertaken to know the prevalence of SA-RVS and compare vancomycin MIC by agar dilution and E test.

Methods

A prospective study was undertaken at tertiary care hospital; 232 clinical MRSA isolates were included. Vancomycin MIC was undertaken by agar dilution method and E test.

Results

All isolates were sensitive to Linezolid. Two MRSA isolates had vancomycin MIC ≥4 μg/ml; vancomycin MIC50 and MIC90 of MRSA isolates was 0.5 and 0.2 μg/ml respectively by agar dilution method. There was agreement over 93.5% isolates in vancomycin susceptibility by agar dilution and E test. E test had sensitivity and positive predictive value of 1.0 (CI – 0.34–1.0) and 0.5 (CI – 0.17–0.83) respectively compare to agar dilution method.

Conclusions

MRSA isolates continues to be susceptible to vancomycin and Linezolid. E test was found equally suitable in initial screening for vancomycin susceptibility. Due to geographic variation in prevalence, there is need of ongoing surveillance of SA-RVC.     

Molecular nature of alpha-globin genes in the Saudi population

Alpha-thalassemia (α-thal) is a disorder caused by the deletion of single or double α-globin genes, and/or point mutations in the α-globin genes. There are 2 common types of α-globin genes; HBA2 and HBA1. Recently, it has been discovered that the HBA2 gene is replaced by a unique HBA12 gene convert in 5.7% of the Saudi population. The α-globin genes have been emerging as a molecular target for the treatment of β-thalassemia (β-thal). Hence, it is essential to understand the molecular nature of α-globin genes to treat the most prevalent hemoglobin disorders, such as sickle cell disease, α-thal, and β-thal prevalent in the Kingdom of Saudi Arabia. Thirty-two different α-globin genotypes have been observed in the Saudi population. This review outlines the classification of the α-globin genes on the basis of their molecular nature and complex combinations of α-globin genes, and their variants predominant in Saudis.Thalassemia (alpha [α] and beta [β]) and sickle cell disease (SCD) are the most prevalent hemoglobin disorders in the Kingdom of Saudi Arabia.1-11 Alpha-thalassemia (α-thal) is a disorder caused by the deletion of single or double α-globin genes, and/or point mutations in the α-globin genes.10 Alpha-thalassemia phenotype varies from very mild or microcytic hypochromic anemia to a lethal form of hemolytic anemia, depending on the type of molecular defects in α-globin genes.10 Alpha-globin genes are of 2 types; hemoglobin alpha 1 (HBA1) and hemoglobin alpha 2 (HBA2). The HBA1 and HBA2 genes are located in the p arm (short arm) of chromosome 16 at region one, band 3, and sub-band 3. Altogether there are 4 genes (α₁α₂/α₁α₂) in a person corresponding to 4 α-globin proteins. Out of the 4 α-globin genes, 2 are inherited from the father, and others from the mother. Loss of single or all of these genes results in different types of α-thal. The α-globin protein is a subunit of hemoglobin, which is a larger protein in red blood cells (RBC) that carries oxygen throughout the body. Alpha-globin proteins of HBA2 and HBA1 genes are nearly identical. Alpha-globin protein is subunit of fetal hemoglobin (HbF), which is active only in the human fetus and in the newborn period until roughly 6 months old. Exceptionally, in non-transfusion dependent β-thal cases, HbF is elevated and active throughout life. Reduced synthesis of α-globin protein ameliorates the clinical severity of β-thallassemia. Alpha-globin is an emerging molecular target for treatment of β-thal.12 Hence, it is essential to understand the different types of globin genes and its variants prevalent in Saudi population.

The α-globin genes in Saudis

A number of research reports were available on the analysis of mutations and deletion in the α-globin genes from Saudi population.1-11,13-20 Commonly, α-globin genes are of 2 types (HBA2 and HBA1), while in Saudis it is of 3 types namely HBA2 (α₂), HBA1 (α₁), and HBA12 (α₁₂).8 The HBA12 is a new convert of the HBA2 gene, discovered in Saudis. The HBA2 has been replaced with HBA12 in 5.7% of Saudi population.8 The poly A mutation [AATAAA>AATAAG] (41%), and the α^3.7 α⁺ heterozygous deletion are the most reported mutations and deletion in Saudi population. Co-inheritance of α-globin gene and β-globin gene mutations are prevalent in Saudis.7-9

The α-globin gene conversion

A recent study by Borgio et al8 using direct sequencing of HBA1 and HBA2 in Saudis revealed a new gene, which was very closely related to the common α-globin genes (HBA1 and HBA2). They named the new gene as 2_. They clearly described that the formation the HBA12 was formed by the combination of HBA1 and HBA2 gene sequences through a process called gene conversion (Figure 1). Gene conversion is the process of the transfer of genetic material unidirectionally from a donor to an acceptor.21 Gene conversion between the 2 homologous α-globin genes is common.8 The HBA12 gene has the region starting -6bp until 581bp (3’ promoter, exon1, IVSI, exon2, and 5’IVSII) from HBA1 gene, and 774bp (3’enhancer) onwards from HBA2 gene.8 The region in-between 581bp and 774bp (3’ IVSII, exon 3’, and 5’ enhancer) were matching with HBA1 and HBA2, hence this region was considered as an indistinguishable region.8 The α-globin protein from HBA12 gene is not available in the literature, detailed studies are needed to confirm the similarity of HBA12 protein with the α-globin protein of HBA2 and HBA1 genes.Open in a separate windowFigure 1An image showing 3 types of globin genes prevalent in the Saudi population: HBA2 (α2), HBA1 (α1), and HBA12 (α12). The α2 gene is colored in nut brown and α1 gene is colored in violet. The undistinguished sequences (α1 or α2 ?) are colored in black. Reproduced and modified from: Borgio JF, AbdulAzeez S, Al-Nafie AN, Naserullah ZA, Al-Jarrash S, Al-Madan MS, et al. A novel HBA2 gene conversion in cis or trans: “α12 allele” in a Saudi population. Blood Cells Mol Dis 2014; 53: 199-203.8 With permission from Elsevier.A total of 5.7% of the study population including sickle cell trait, hemophilia-A patient, SCD patients, and β-thal major patients were reported to have the new gene convert, α₁₂ gene. The inheritance of the HBA12 gene was proven on an elaborated family study, any one of the parent of individual with HBA12 was a carrier for the HBA12 gene. The HBA12 gene was reported to be co-inherited with any one of the common α-globin gene defects like α^3.7 deletion, ααα^3.7 triplications, and α^4.2 deletion, but not always. The reported HBA12 gene from Saudis was distinguishably different from the α-globin patch works, such as α₂₁₂ and α₁₂₁.8 Except the nullizygous, all the other 3 types (hemizygous α₁-/α₁α₁₂, heterozygous α₁α₂/α₁α₁₂, and homozygous α₁α₁₂/α₁α₁₂) of zygosities were observed for the α₁₂ gene from Saudi population. α-globin gene convert was highly prevalent in the Saudis due to the high percentage of consanguinity. Slight increase in mean corpuscular volume, elevated HbF (α₂γ₂), and reduced HbA₂ (α₂δ₂) were noted on the subjects with α₁₂ gene convert.8

Alpha₁₂ and HbA₂

Deep analysis by Borgio et al8 revealed the influence of the α₁₂ gene on the level of hemoglobin A₂ (HbA₂). Subgrouping the population with the α₁₂ gene into 6 groups (HbS^carrier; β-thal^carrier; β-thal^major/α-thal^carrier; SCD^+ve, and α-thal^carrier; HbS^carrier α-thal^carrier; and Normal^{No α-thal&β-thal}) by the authors was able to identify the reduced level of HbA₂ in the first 5 groups with α₁₂ gene.8 Thorough investigation on the large-scale micromapping of phenomics for this α₁₂ gene is mandatory to uncover the hematologic effects of the new α₁₂ gene.

Alpha-globin genotypes

The term “α-globin genotype” refers to the genetic makeup of an individual’s complete set of α-genes. Two alleles (α/α) at each α-globin gene position is called diploid. In general, 2 pairs of alleles from 2 α-globin genes, α₁/α₁ (HBA1) and α₂/α₂ (HBA2) represents the genotype (α₁α₂/α₁α₂) of an α-globin gene. In terms of Saudi population, the HBA2 gene has been replaced with HBA12 gene convert, a pair of alleles α₁₂/α₁₂ of an α-globin gene convert, HBA12 specific to Saudis represents the genotype, α₁α₁₂/α₁α₁₂. Hence there are 3 genotypes, α₁α₂/α₁α₂, α₁α₂/α₁α₁₂, and α₁α₁₂/α₁α₁₂ are the possible normal genotypes in Saudi population (7,15 Alpha-globin genotype of each individual contributes to its α-thal phenotype. On the basis of genotypes, α-thal can be classified into 4 types, group one: deletion of 4 α-globin genes, termed Hb Bart’s; group 2: deletion of 3 α- globin genes, called HbH disease; group 3: deletion of 2 α- globin genes, named α-thal trait; group 4: deletion of one α-globin gene, designated α-thal Silent (Figure 2). Two particular identical alleles are described as homozygous (for example, α^3.7 homozygous deletion -α^3.7/-α^3.7), and if the 2 alleles differ, it is termed as heterozygous (for example, α^3.7 heterozygous deletion -α^3.7/αα). Hemizygous (for example, α₁-^4.2/α₁α₁₂) form of α-globin genotypes were also reported from Saudis.8 Severity of the α-thal disorder is indirectly proportional to the number of functional α-globin genes. The severities of α-thal tend to be more in group one results from the loss of all 4 α-globin genes, while signs and symptoms are almost nil in group 4 (Figure 2). Techniques for the updated genotyping (the process of determining a genotype) of α-globin genes in Saudis for the proper diagnosis should be given to health professional.

Table 1

Alpha-globin genotypes prevalent in Saudi population according to various studies in Saudi Arabia.Open in a separate windowOpen in a separate windowFigure 2Molecular types of thalassemia and types of globin gene deletions prevalent in the Saudi population. Filled boxes of genes α1, α2, and α12 indicates normal genes, while empty boxes of genes α1, α2, and α12 indicate the deleted genes.

Down regulation factors of the α-globin gene expression

In general, down regulation of the expression of the α-globin genes due to mutations in ATRX (α-thal x-linked mental retardation) gene, usually lead to α-thal like phenotype.22,23 Very recently, there were 4 novel mutations (IVS I-5(G→C), Cd39(C→T), c.623delA, and c.848T>C) on ATRX gene reported in Saudi population. The 2 exonic mutations (c.623delA and c.848T>C) were reported in patients co-inherited with α-globin genes mutations.9 The study is a clear alarm that the α-thal-like phenotype in Saudi population may be due to mutations in α-globin genes, or in ATRX gene. It seems reasonable to suggest that screening for the presence of mutations in the ATRX gene along with mutations in the HBA2, HBA1, and HBA12 genes are essential for proper identification of the disease burden in this population.The main limitation of this review is that, some of the articles dealing with α-thal within the Saudi population were not publicly accessible full text scholarly articles. Health sector professional should keep themselves updated with the genotyping techniques for α-globin and ATRX genes in Saudis. The very high frequency of α-thal, SCD, and β-thal in the Kingdom and their co-inheritance obliges the addition of sequence based testing system for HBA2, HBA1, HBA12, and ATRX genes along with the existing pre-marital testing program, to detect the risk for the offspring of affected individuals.In conclusion, large-scale screening is mandatory to identify the influence of point mutations and deletion on the phenotype of Saudi population. In-depth, the studies on the prevalence of the sequence variations in α₁₂ and their influence on the phenotypes are needed. Comparative studies on the protein structure and molecular modeling of α₁, α₂, and α₁₂ have to be initiated. Specific diagnostic kits for Saudi population should be developed to identify the sequence defects in α₁, α₂, and α₁₂ genes. The clinical effects due to the changes in α-globin gene expression from the α₁₂ gene should be studied at large-scale. Cellular studies are needed to understand the process of down regulation of α-globin gene expression due to ATRX gene mutation in Saudis.     

Follow-up of N400 in the Rehabilitation of First-episode Schizophrenia

Background:

The N400 component of event-related potentials (ERP) has recently drawn widespread attention at home and abroad. This study was to explore the relationship between N400 changes and risperidone treatment and rehabilitation in first-episode schizophrenia (FES).

Methods:

ERP component N400 was recorded by Guangzhou Runjie WJ-1 ERP instruments, in 58 FES before and 6 months, 15 months after risperidone treatment, and in 62 normal controls. The patients’ syndromes were assessed by Positive and Negative Syndrome Scale (PANSS). And the stimuli are Chinese sentences with matching (congruent) or mismatching (incongruent) ending words.

Results:

N400 latencies were prolonged, and amplitudes were decreased in Cz, Pz, Fz, C3, C4, in FES compared with in NC, before treatment. The prolonged N400 latencies and decreased amplitudes were negatively correlated with the patients’ positive scale and total scale of PANSS. There are significant differences of N400 amplitudes and latencies in 6 months and 15 months follow-up after treatment. Before treatment, 6 months and 15 months after treatment, N400 latencies are 446 ± 35 ms, 440 ± 37 ms, 414 ± 31 ms (F = 9.72, P < 0.01) in incongruent situation; N400 amplitudes are 5.2 ± 4.6 μV, 5.7 ± 4.8 μV, 7.3 ± 5.0 μV (F = 2.06, P > 0.05) in congruent situation, and 8.5 ± 5.9 μV, 10.1 ± 5.0 μV, 11.9 ± 7.0 μV (F = 3.697, P < 0.05) in incongruent situation.

Conclusions:

N400 could be used to predict the effects of treatment of schizophrenia to some degree. The linguistic and cognitive impairment in schizophrenia can be improved by antipsychotic drugs.     

Dexmedetomidine-midazolam versus Sufentanil-midazolam for Awake Fiberoptic Nasotracheal Intubation: A Randomized Double-blind Study

Background:

Awake fiberoptic intubation (AFOI) is usually performed in the management of the predicted difficult airway. The aim of this study was to evaluate the feasibility of dexmedetomidine with midazolam (DM) and sufentanil with midazolam (SM) for sedation for awake fiberoptic nasotracheal intubation.

Methods:

Fifty patients with limited mouth opening scheduled for AFOI were randomly assigned to two groups (n = 25 per group) by a computer-generated randomization schedule. All subjects received midazolam 0.02 mg/kg as premedication and airway topical anesthesia with a modified “spray-as-you-go” technique. Group DM received dexmedetomidine at a loading dose of 0.5 μg/kg over 10 min followed by a continuous infusion of 0.25 μg·kg⁻¹·h⁻¹, whereas Group SM received sufentanil at a loading dose of 0.2 μg/kg over 10 min followed by a continuous infusion of 0.1 μg·kg⁻¹·h⁻¹. As necessary, since the end of the administration of the loading dose of the study drug, an additional dose of midazolam 0.5 mg at 2-min intervals was given to achieve a modified Observers’ Assessment of Alertness/Sedation of 2–3. The quality of intubation conditions and adverse events were observed.

Results:

The scores of ease of the AFOI procedure, patient''s reaction during AFOI, coughing severity, tolerance after intubation, recall of the procedure and discomfort during the procedure were comparable in both groups (z = 0.572, 0.664, 1.297, 0.467, 0.895, and 0.188, respectively, P > 0.05). Hypoxic episodes similarly occurred in the two groups, but the first partial pressure of end-tidal CO₂ after intubation was higher in Group SM than that in Group DM (45.2 ± 4.2 mmHg vs. 42.2 ± 4.3 mmHg, t = 2.495, P < 0.05).

Conclusions:

Both dexmedetomidine and sufentanil are effective as an adjuvant for AFOI under airway topical anesthesia combined with midazolam sedation, but respiratory depression is still a potential risk in the sufentanil regimen.     

Vitamin B12 Content of Circulating Leukocytes as an Aid in the Differentiation of the Acute Leukemias

From 25 patients with acute leukemia 116 specimens of leukocytes were assayed microbiologically for total vitamin B₁₂ to determine if variation in vitamin B₁₂ content would help in differentiating the acute leukemias. The mean cell vitamin B₁₂ levels (μμg./10⁸ cells) in the different types of leukemia were: lymphoblastic 464, myeloblastic 1058 and monocytic 200. Cell vitamin B₁₂ levels above the normal range (100-800 μμg./10⁸ cells) are suggestive of myeloblastic leukemia. The only elevated cell vitamin B₁₂ levels comparable to those found in myeloblastic leukemia were in reticulum cell leukemia, and this type of leukemia was not difficult to diagnose morphologically. Blast cells contained more vitamin B₁₂ than mature cells of the same series; there was a significant positive correlation between the percentage of blast cells and cell levels of total vitamin B₁₂ in both lymphoblastic and myeloblastic leukemia.     

Effect of Inhaled Budesonide on Interleukin-4 and Interleukin-6 in Exhaled Breath Condensate of Asthmatic Patients

Background:

Studies of interleukin (IL)-4 and IL-6 in the exhaled breath condensate (EBC) of asthmatic patients are limited. This study was to determine the effect of inhaled corticosteroid (ICS) treatment on IL-4 and IL-6 in the EBC of asthmatic patients.

Methods:

In a prospective, open-label study, budesonide 200 μg twice daily by dry powder inhaler was administered to 23 adult patients with uncontrolled asthma (mean age 42.7 years) for 12 weeks. Changes in asthma scores, lung function parameters (forced expiratory volume in 1 s [FEV₁], peak expiratory flow [PEF], forced expiratory flow at 50% of forced vital capacity [FEF₅₀], forced expiratory flow at 75% of forced vital capacity, maximum mid-expiratory flow rate) and the concentrations of IL-4 and IL-6 in EBC were measured.

Results:

Both asthma scores and lung function parameters were significantly improved by ICS treatment. The mean IL-4 concentration in the EBC was decreased gradually, from 1.92 ± 0.56 pmol/L before treatment to 1.60 ± 0.36 pmol/L after 8 weeks of treatment (P < 0.05) and 1.54 ± 0.81 pmol/L after 12 weeks of treatment (P < 0.01). However, the IL-6 concentration was not significantly decreased. The change in the IL-4 concentration was correlated with improvements in mean FEV₁, PEF and FEF₅₀ values (correlation coefficients −0.468, −0.478, and −0.426, respectively).

Conclusions:

The concentration of IL-4 in the EBC of asthmatic patients decreased gradually with ICS treatment. Measurement of IL-4 in EBC could be useful to monitor airway inflammation in asthmatics.