Attention deficit hyperactivity disorder and environmental toxic metal exposure in the United Arab Emirates

No systematic studies have been carried out on the effects of toxic metals on childhood behavior in the Gulf Region including the UAE. The relationship between blood levels of heavy metals and Attention Deficit Hyperactivity disorder (ADHD) were explored in school-aged children of UAE and it was found that increased blood concentrations of lead (Pb), manganese (Mn) and zinc (Zn) were significantly associated with ADHD. The findings suggest that monitoring for exposure to heavy metal levels and education on potential child health hazards related to them are indicated.

Overexpression of apolipoprotein E4 increases kainic-acid-induced hippocampal neurodegeneration

Apolipoprotein E (apoE) has an intricate biological function in modulating immune responses and apoE isoforms exhibit diverse effects on neurodegenerative and neuroinflammatory disorders. In the present study, we investigated the individual roles of apoE isoforms in the kainic acid (KA)-induced hippocampal neurodegeneration with focus on immune response and microglia functions. ApoE2, 3 and 4 transgenic mice as well as wild-type (WT) mice were treated with KA by intranasal route. ApoE4 overexpressing mice revealed several peculiarities as compared with other transgenic mice and WT mice, i.e. (1) they had more severe KA-induced seizures than apoE2 and 3 mice, (2) they exhibited neuron loss in hippocampus that was higher than in apoE2, 3 and WT mice, (3) KA administration resulted in higher counts of their head drops in the cross-area of elevated plus-maze, (4) they showed lower KA-induced rearing activity than apoE2 mice in the open-field test, (5) their KA-induced microglial expression of MHC-II and CD86 was elevated compared to apoE3 mice, (6) the KA-induced increase of microglial iNOS was higher than that in the other groups of mice, and (7) the TNF-α and IL-6 expression was decreased 7 days after KA application compared to untreated mice and mice treated 1 day with KA. However, the signaling pathway of NFκB or Akt seemed not to be involved in apoE-isoform dependent susceptibility to KA-induced neurotoxicity. In conclusion, over-expression of apoE4 deteriorated KA-induced hippocampal neurodegeneration in C57BL/6 mice, which might result from a higher up-regulation of microglia activation compared to apoE2 and 3 transgenic mice and WT mice.

Medicinal Chemistry and Actions of Dual and Pan PPAR Modulators

Peroxisome proliferator-activated receptor (PPAR) agonists are used as adjunct therapy in the treatment of diabetes mellitus. Fibrates, including fenofibrate, gemfibrozil, benzafibrate, ciprofibrate, and clofibrate act on PPAR alpha to reduce the level of hypertriglyceridemia. However, agonists (ligands) of PPAR-beta/delta receptors, such as tesaglitazar, muraglitazar, ragaglitazar, imiglitazar, aleglitazar, alter the body's energy substrate preference from glucose to lipids and hence contribute to the reduction of blood glucose level. Glitazones or thiazolidinediones on the other hand, bind to PPAR-gamma receptors located in the nuclei of cells. Activation of PPAR-gamma receptors leads to a decrease in insulin resistance and modification of adipocyte metabolism. They reduce hyperlipidaemia by increasing the level of ATP-binding cassette A1, which modifies extra-hepatic cholesterol into HDL. Dual or pan PPAR ligands stimulate two or more isoforms of PPAR and thereby reduce insulin resistance and prevent short- and long-term complications of diabetes including micro-and macroangiopathy and atherosclerosis, which are caused by deposition of cholesterol. This review examines the chemical structure, actions, side effects and future prospects of dual and pan PPAR agonists.

The effect of oxime reactivators on muscarinic receptors: functional and binding examinations

The antidotal treatment of organophosphorus poisoning is still a problematic issue since no versatile antidote has been developed yet. In our study, we focused on an interesting property, which does not relate to the reactivation of inhibited acetylcholinesterase (AChE) of some oximes, but refers to their anti-muscarinic effects which may contribute considerably to their treatment efficacy. One standard reactivator (HI-6) and two new compounds (K027 and K203) have been investigated for their antimuscarinic properties. Anti-muscarinic effects were studies by means of an in vitro stimulated atrium preparation (functional test), the [(3)H]-QNB binding assay and G-protein coupled receptor assay (GPCR, beta-Arrestin Assay). Based on the functional data HI-6 demonstrates the highest anti-muscarinic effect. However, only when comparing [(3)H]-QNB binding results and GPCR data, K203 shows a very promising compound with regard to anti-muscarinic potency. The therapeutic impact of these findings has been discussed.

APOE ε3 attenuates experimental autoimmune neuritis by modulating T cell, macrophage and Schwann cell functions

Human apolipoprotein E (apoE) is a 34.2kDa glycosylated protein with three isoforms (apoE2, apoE3 and apoE4). Experimental autoimmune neuritis (EAN), an animal model for human Guillain-Barré syndrome, is an immune-mediated experimental disorder of the peripheral nervous system (PNS). Increased susceptibility to EAN in apoE deficient mice has been previously found. To elucidate the isoform-dependent effects of apoE on EAN, we used human apoE2, E3 and E4 transgenic mice (Tg) immunized with P0 peptide 180-199, as well as T cell proliferation test, macrophage and Schwann cell (SC) cultures to investigate the effects of apoE isoforms on the functions of T cells, macrophages and SCs both under naïve conditions and in EAN. Clinical signs of EAN were most severe in wild type (WT) C57BL/6 mice and apoE4 Tg mice, followed by apoE2 Tg mice and apoE3 Tg mice (WT≈E4>E2>E3, p<0.01). At the nadir of EAN, spleen weight and lymphocyte proliferation were in line with the clinical severity of the disease. Proliferation tests of purified T cells from naive mice stimulated with phytohemagglutinin or interleukin-12 showed isoform-specific differences (WT≈E4>E3≈E2, p<0.01). Macrophages from both naïve and EAN mice produced nitric oxide upon inflammatory stimulation with lipopolysaccharide, interferon-γ, polyinosinic:polycytidylic acid or combinations thereof, in an isoform-dependent manner (WT≈E4>E2>E3, p<0.01). Generalized intervention with 1400W, a specific inducible nitric oxide synthase inhibitor, significantly suppressed the clinical course of EAN in apoE2, E3 and E4 Tg mice and in WT mice. During the recovery stage of disease, the highest expression of CD178 (FasL) on SCs was found in apoE3 Tg mice. Our data support an isoform-dependent effect of apoE on EAN. This might be due to the isoform-specific effects of apoE on functions of T cells, macrophages and SCs, which contribute to the distinct clinical courses of EAN. ApoE3 might not only inhibit the onset and suppress the clinical severity of EAN, but also enhance the termination of immune responses in the PNS.

Nigella sativa extract as a potent antioxidant for petrochemical-induced oxidative stress

Various beneficial properties has been attributed to Nigella sativa, including its antioxidant potential. Previously, it was reported that supercritical fluid extraction (SFE) could be used to obtain N. sativa extract rich in antioxidants. In the present study, N. sativa extracts prepared using the previously optimized SFE as well as the traditional Soxhlet extraction approaches were analyzed for various known antioxidants. N. sativa extracts were found to prevent protein carbonyl formation as well as depletion of intracellular glutathione (GSH) in fibroblasts exposed to toluene. Furthermore, partially purified SFE and Soxhlet fractions could prevent loss of hepatic GSH in toluene-induced oxidative stressed Wistar rats as well as in L929 fibroblasts. The results showed that SFE-produced N. sativa extract is richer in antioxidants than the Soxhlet approach. It was also shown using preparative silica gel and reverse phase chromatography that different fractions of SFE-extracted or Soxhlet-extracted N. sativa had different levels of protective effects with regards to GSH depletion in vivo as well as in cell culture. Although fractions rich in thymoquinone were found to be most potent in terms of antioxidant capacity, the data indicates that the protective effects of N. sativa may not only be due to thymoquinone, but perhaps other antioxidants.

Attenuation of stress-induced gastric lesions by lansoprazole, PD-136450 and ranitidine in rats

Combining restraint with cold temperature (4°C) consistently induces gastric ulceration in rats after 3.5 h. The cold restraint-stress (CRS) method provides a suitable model for acute ulcer investigations. This study compares the antiulcer activities of lansoprazole (a proton pump inhibitor), PD-136450 (CCK(2)/gastrin receptor antagonist) and ranitidine (histamine H(2) receptor antagonist) on CRS-induced gastric ulcers in rats. The results have shown that lansoprazole, which is a potent anti-secretory agent, provides complete protection in this model of ulcer formation. The use of indomethacin pretreatment to inhibit the prostaglandin (PG) synthesis and N(G)-nitro L-arginine methyl ester (L-NAME) pretreatment to inhibit nitric oxide synthase did not alter the lansoprazole-induced inhibition of ulcer index obtained in the untreated Wistar rats indicating that these two systems were not involved in the activation of lansoprazole. PD-136450, an effective anti-secretory agent against gastrin- but not dimaprit-induced stimulation, evoked a dose-dependent inhibition of CRS-induced gastric ulcers. The results show that both PG and nitric oxide pathways can influence the inhibitory effect of PD-136450 against CRS-induced gastric ulcer. The antiulcer activities of both lansoprazole and PD-136450 were compared to that of ranitidine. The results showed that ranitidine was more potent than lansoprazole and PD-136450 in inhibiting CRS-induced gastric ulcers and its effect was shown to be influenced by PG as well as nitric oxide synthase. The results of this study have demonstrated that although lansoprazole, PD-136450 and ranitidine were protective against CRS-induced gastric ulcers, the antiulcer activities of PD-136450 and ranitidine involved both PG and nitric oxide pathways, while lansoprazole acted independently of these two systems during CRS.

High dose epoetin beta in the first weeks following renal transplantation and delayed graft function: Results of the Neo-PDGF Study

Erythropoietin promotes nephroprotection in animal models of ischemia-reperfusion injury. Neorecormon and Prevention of Delayed Graft Function (Neo-PDGF) is a French open-label multicenter randomized study to evaluate the effect of high doses of epoetin beta (EPO-beta) during the first 2 weeks of renal transplantation on renal function in patients at risk for delayed graft function (DGF). One hundred and four patients were included in the study. Patients randomized in treatment group (A) received four injections of EPO-beta (30.000 UI each), given before surgery and at 12 h, 7 days and 14 days posttransplantation. Patients randomized in control group (B) did not receive EPO-beta. Immunosuppression included induction with basiliximab and maintenance therapy with steroids, mycophenolate mofetil and tacrolimus. At 1 month posttransplant, the estimated glomerular filtration rate (MDRD formula) was 42.5 +/- 19.0 mL/min in the EPO-beta group and 44.0 +/- 16.3 mL/min in the control group (p = ns). The frequency of DGF was similar in both groups (32% vs. 38.8%; p = ns). No difference in the incidence of serious adverse events was observed. (ClinicalTrials.gov number, NCT00815867.).

Medicinal chemistry of antiviral/anticancer prodrugs subjected to phosphate conjugation

Certain xenobiotics are given in the "prodrug" form. Either the human body, or one compartment of the body, or the targeted virus itself metabolizes the prodrug into its active form. The bioprecursor form of drugs is used for a wide variety of reasons, namely: to make drug penetration into the target organ (mainly to the brain through the blood-brain-barrier) possible, eliminate unpleasant taste, alter (either increasing or decreasing) the half life of the active component or supply more than one active components to the body.

Changes in tissue levels of growth hormone, insulin-like growth factor-I, and somatostatin in the femurs of hind-limb immobilized rats

Immobilization of an extremity causes skeletal muscle atrophy and a dramatic increase in bone resorption. Growth hormone (GH) is known to play an important role in bone remodeling mediated in part by local insulin-like growth factor-I (IGF-I). In this study, we investigated changes in the levels of GH and IGF-I peptide in bone extracts from the femur after hind-limb immobilization for 5 days, 2, 4, and 8 weeks. The levels of somatostatin, which interacts with GH, were also measured in the bone extracts. GH levels increased after 8 weeks of hind-limb immobilization whereas the IGF-I concentrations increased after 2 weeks, but returned to control levels at 4 weeks, and decreased after 8 weeks of immobilization. The somatostatin levels in the bone extracts increased only after 8 weeks of hind-limb immobilization. Our findings suggest that, after hind-limb immobilization, changes in the concentrations of GH, IGF-I, and somatostatin in bone may mediate bone resorption either directly or through interaction with other factors.

The next generation of cholinesterase inhibitors

Clinical trials with tacrine (THA) have resulted in elevations of liver enzymes in Alzheimer patients that showed improvement. In an effort to minimize these side effects several THA analogues were synthesized. These analogues were compared to THA in biochemical as well as behavioural studies. The biochemical effects of these drugs on plasma cholinesterase activity and cholinergic receptors as well as the effect of these drugs on spatial learning in adult rats were examined. It is possible that some of these analogues with more potent cholinergic effect than THA might be the next generation of cholinesterase inhibitors which can be useful in the treatment of Alzheimer's disease.

Chronic lymphocytic leukemia: a hazardous condition before kidney transplantation

Long-term survival of patients with chronic lymphocytic leukemia (CLL) is over 10 years, and such patients are thus potential kidney recipients in the case of superimposed end-stage renal disease. However, the renal and patient outcome in this condition is unknown. We report the charts of four patients with CLL who were engrafted in France with a deceased-donor kidney and underwent routine triple immunosuppressive therapy. The results show that these patients developed severe infectious episodes (fatal in one case) and tumoral complications including rapid progression of CLL in two cases. Moreover, the graft may be infiltrated and damaged by monoclonal B cells: one patient lost his graft 14 months after transplantation. Various therapeutic options (modifications of the immunosuppressive regimen, anti-CD20 antibodies, irradiation of the graft) showed little (if any) efficacy. Therefore, we believe that CLL is a too hazardous condition to envisage solid organ transplantation with a routine immunosuppressive regimen, and we propose a more appropriate approach.

Estrogen receptor alpha gene polymorphism and breast cancer

Estrogen and estrogen receptors play important roles in the proliferation and development of breast cancer. Several genetic alterations identified in the estrogen receptor alpha gene (ESR1) are thought to influence the expression or function of this protein, and many have been evaluated for their role in breast cancer predisposition. The aim of this study was to evaluate the role of the C325G single nucleotide polymorphism (SNP) in the ESR1 in predisposition to breast cancer. The candidate SNP C325G in ESR1, exon 4 was genotyped in breast cancer patients and in healthy controls that were age and sex matched. Genotyping was performed using both single-stranded conformational polymorphism (SSCP) and a higher throughput allelic discrimination method using real-time PCR. Data on clinical features and demographic details were collected. Significant association of breast cancer risk was shown in the subgroup of women 50 years and younger who had the C allele (OR: 2.28, 95% CI: 1.10-4.72) (P= 0.03). However, the overall susceptibility to breast cancer was not significant, although all estimates were in the direction of a higher risk in women with CC genotypes. This study found significant evidence that polymorphism within the low penetrance ESR1 is associated with breast cancer susceptibility in women of 50 years or younger. There is also an indication that G allele is protective (compared to C allele).

TNF-alpha receptor 1 deficiency enhances kainic acid-induced hippocampal injury in mice

The exact role of TNF-alpha in excitotoxic neurodegeneration of the brain is unclear. To address this issue, the kainic acid (KA)-induced hippocampal injury model, a well-characterized model of human neurodegenerative diseases, was used in TNF-alpha receptor 1 (TNFR1)-knockout (TNFR1-/-) mice in the present study. After nasal application of a single dose of 40 mg of KA per kilogram body weight, TNFR1-/- mice showed significantly more severe seizures than the wild-type mice. In addition, obvious neurodegeneration, enhanced microglia activation, and astrogliosis in the hippocampus, as well as increased locomotor activity, were found in TNFR1-/- mice compared with the wild-type controls 8 days after KA delivery. Moreover, CC chemokine receptor 3 expression on activated microglia was increased 3 days after KA treatment in TNFR1-/- mice, as measured by flow cytometry. These data suggest that TNF-alpha may play a protective role through TNFR1 signaling.

Trace element composition of plasma and breast milk of well-nourished women

A wide variation in the composition of breast milk has been reported from various countries. This study was undertaken to determine the trace element content of breast milk and plasma in lactating women. Mothers of children 4 weeks to 80 weeks in age, were studied. Blood and breast milk from the mothers were analysed for trace element content. Prepared samples were analysed using ICP-MS. 209 women agreed to take part in the study, 68 of whom were from the UAE and 124 were other nationalities (17 did not fill the this part of the questionnaire). Ninety-seven infants were male. The concentration of different trace elements in blood and breast milk were little different between women from the UAE and those from outside the UAE. Molybenum, chromium and arsenic significantly increased with increasing age of the infant, while manganese, copper and zinc significantly decreased with increasing age of the infant. The trace element concentrations of breast milk and maternal blood were comparable to published values. Normal values for plasma and breast milk trace metal concentrations have been obtained for UAE women.