Abdullah Salih Alhomida

Methemoglobin reductase activity and in vitro sensitivity towards oxidant induced methemoglobinemia in Swiss mice and Beagle dogs erythrocytes

The NADH methemoglobin-reductase (EC 1.6.2.2) is mainly responsible for the maintenance of hemoglobin in its reduced and active state. The present study reveals the comparative status of this enzyme in normal Beagle dogs, rats, mice, mastomys and hamsters erythrocytes. The spectrophotometric and electrophoretic determinations showed that the above mentioned enzyme was deficient in the Beagle dogs erythrocytes. Furthermore, in vitro studies on the sensitivity of these rodents and Beagle dogs hemolysate towards oxidants, like primaquine and sodium nitrate, depicted a higher level of methemoglobin formation in the Beagle dogs hemolysate as compared to that of the rodent species. The deficiency of methemoglobin reductase in Beagle dogs erythrocytes could be responsible for their increased sensitivity towards oxidant induced methemoglobinemia.

Effect of mercuric chloride on various hydroxyproline fractions in rat serum.

Mercuric chloride (HgCl2) disturbs the collagen metabolism in the body which is reflected by altered hydroxyproline fractions in the serum. The aim of the present investigation was to study the effect of HgCl2 treatment on various hydroxyproline (Hyp) fractions in rat serum and the effect of 2,3-dimercapto-1-propane sulfonic acid (DMPS) treatment on serum Hyp fractions in HgCl2 treated rats. Other parameters studied included body weight, food intake, water intake and kidney weight. Doses of HgCl2 used were 0.1, 0.5, 1.0, 2.0, 3.0 mg/kg body weight and that of DMPS was 100 mg DMPS/kg body weight. All the doses of HgCl2 used caused significant (p < 0.01) alterations in free, peptide-bound and protein-bound Hyp in the serum when compared with control rats but a dose of 2 mg/kg body weight caused significant (p < 0.001) alteration even in the total serum Hyp when compared to control rats. Administration of DMPS prior HgCl2 treatment of rats sacrificed 24 h after the treatment caused a significant decrease of 52% (p < 0.01) in free Hyp when compared to similar HgCl2 treated rats. DMPS treatment with HgCl2 also caused an increase of 61% (p < 0.001) and 114% (p < 0. 001) in peptide- and protein-bound Hyp respectively, when compared to HgCl2 treated rats sacrificed 24 h after mercuric chloride and DMPS treatment. Administration of DMPS followed by HgCl2 to rats which were sacrificed 48 h later caused no significant change in the total and free Hyp when compared to HgCl2 treated rats which were sacrificed 48 h after the treatment. But there was a significant decrease of 40% (p < 0.001) in peptide-bound Hyp and an increase in of 77% (p < 0.001) in protein-bound Hyp when compared to HgCl2 treated rats sacrificed 48 h after the treatment. The present study shows that HgCl2 treatment caused significant alterations in serum Hyp fractions reflecting disturbed composition of connective tissues which were not reversed by DMPS treatment. (Mol Cell Biochem 271: 159–165, 2005)

EFFECT OF TUMOR NECROSIS FACTOR ON HEPATIC OXIDATIVE STRESS AND ANTIOXIDANT DEFENSE INDICES IN NORMAL AND PLASMODIUM YEOLII NIGERIENSIS INFECTED MICE

Background: Plasmodium yoelii nigeriensis (P. y. nigeriensis) produces lethal malaria infection in Swiss albino mice. Reactive oxygen species (ROS) such as superoxide anion, hydrogen peroxide along with endogenously produced tumor necrosis factor (TNF) have been implicated in the pathogenesis of malaria. Objective: Study the effect of TNF on hepatic oxidative stress and antioxidant defense indices in normal and P. y. nigeriensis infected mice. Methods: Mice were divided into four groups. Normal group, TNF treated group, P. y. nigeriensis infected group, and P. y. nigeriensis infected mice treated with TNF group (250 μg/kg body weight, IP). Results: TNF treatment of normal mice caused a highly significant decrease in hepatic superoxide dismutase (SOD) while changes in other oxidative stress and antioxidant defense indices were nonsignificant. On the other hand, TNF treatment of P. y. nigeriensis infected mice caused a highly significant increase in hepatic xanthine oxidase, lipid peroxidation and a significant decrease in hepatic SOD with respect to infected mice. Conclusion: These results suggest that exogenous TNF acts synergistically with P. y. nigeriensis infection to generate oxidative stress in the host and also causes an impairment of antioxidant defense enzyme such as superoxide dismutase.

A study on distribution of different hydroxyproline fractions in the bovine ocular tissues.

The purpose of this study was to determine the content of total, free, peptide-bound, protein-bound, soluble- and insoluble-collagen hydroxyproline (Hyp) in tissues of bovine eye. The results show that lens had the highest content of free Hyp. This was followed by cornea, retina, iris and aqueous humor. The difference between the Hyp content of lens and iris (p < 0.01) and aqueous humor (p < 0.001) was significant. The peptide-bound Hyp was highest in iris followed by cornea, ciliary body, sclera, lens, aqueous humor and retina. Significant differences (p < 0.001) was observed between the concentration of peptide-bound Hyp of iris and ciliary body, sclera, lens, aqueous humor and retina. Protein-bound Hyp was highest in iris, followed by ciliary body, sclera, cornea, lens, retina and aqueous humor. The difference between the protein-bound Hyp levels of iris and sclera, cornea, lens, retina and aqueous humor was significant (p < 0.001). No peptide-bound and protein-bound Hyp was detected in vitreous humor. Iris had the highest content of total Hyp. This was followed by cornea, ciliary body, sclera, lens, retina, vitreous humor and aqueous humor. The difference in the Hyp content of iris with ciliary body, sclera, lens, retina, vitreous humor and aqueous humor was significant (p < 0.001). Cornea had significantly (p < 0.001) higher content of soluble- and insoluble-collagen Hyp as compared to other tissues. This was followed by ciliary body, sclera, lens, iris and retina. Iris had the highest content of collagen. This was followed by cornea, ciliary body, sclera, lens, retina, vitreous humor and aqueous humor. The difference in the collagen content of iris with ciliary body, sclera, lens, retina, vitreous humor and aqueous humor was significant (p < 0.001).

Expression and localization of sPLA2-III in the rat CNS.

Phospholipases A2 (PLA2) are enzymes that cleave the sn-2 bond of membrane phospholipids to yield free fatty acids and lysophospholipids. Secretory PLA2-III (sPLA2-III) has been suggested to be important for neuronal differentiation, growth and survival, and is highly expressed in the spinal cord. The aim of this study is to elucidate its expression and distribution in different regions of the adult rat CNS. Quantitative RT-PCR analyses showed high levels of sPLA2-III mRNA expression in the brainstem and spinal cord and low expression in the olfactory bulb. Western blot analyses showed high level of expression in the brainstem, spinal cord and cerebral neocortex. A dense band corresponding to the catalytically active, mature/cleaved form, and a faint band corresponding to the full length sPLA2-III were detected in post-mitochondrial supernatants, from different parts of the CNS. Subcellular fractionation of spinal cord homogenates showed that sPLA2-III protein is present in the ‘light membrane/cytosol’ fraction, but not the nucleus, synaptosomal membrane or synaptic vesicle-enriched fractions. sPLA2-III was immunolocalized to neurons in the cerebral neocortex, Purkinje neurons in the cerebellar cortex, periaqueductal gray, red nucleus, spinal trigeminal nucleus and dorsal horn of the spinal cord. Electron microscopy of the spinal cord and cerebral neocortex showed that sPLA2-III was localized in dendrites or dendritic spines, that formed asymmetrical synapses with unlabeled, putatively glutamatergic, axon terminals. The localization of mature/cleaved form of sPLA2-III in postsynaptic structures suggest a physiological role of the enzyme in neurotransmission or synaptic plasticity.

The changes in various hydroxyproline fractions in aortic tissue of rabbits are closely related to the progression of atherosclerosis

BackgroundThe most important function of collagen and elastin is to induce several mechanical parameters which are known to play a dominant role in governing mechanical properties of the blood vessels. The aortic tissue of rabbit is one of the important sources of collagen and elastin. The effects of high fat diet (HFD) on the hydroxyproline (Hyp) fractions in serum and aortic tissues of rabbits and collagen content in the aortic tissues of rabbits have not been documented before. The present study was undertaken to investigate the changes in Hyp fractions in serum and aortic tissues of rabbits and collagen content in the aortic tissues of rabbits during the progression of atherosclerosis. The atherosclerotic model used in this study was the New Zealand white rabbit (male; 12 weeks old). Twenty five rabbits were individually caged, and divided into control group (NOR; n = 10) and HFD group (CHO; n = 15). The control group was fed (100 g/day) of normal (NOR) diet for a period of 15 weeks. The HFD group was fed normal diet supplemented with 1.0% cholesterol plus 1.0% olive oil (100 g/day) for the same period of time.ResultsWe found that the TC, LDLC, and TG (mg/dl) were significantly (p < 0.001) increased in HFD rabbits compared with control rabbits with percentage normalized changes of 1198%, 1591%, and 710%, respectively. The peptide-bound Hyp in the serum was significantly (P < 0.05) increased in HFD rabbits compared with control rabbits with percentage normalized change of 517% while it significantly (P < 0.01) decreased in aortic tissues of HFD rabbits compared with control rabbits with percentage normalized change of 65%. The protein-bound Hyp in the serum was significantly (P < 0.01) increased in HFD rabbits compared with control rabbits with percentage normalized change of 100%; the protein-bound Hyp in the aortic tissues of control rabbits was 235.30 ± 55.14 (Mean ± SD) while it was not detectable (ND) in HFD rabbits. Total serum Hyp showed no significant (P < 0.05) change in HFD rabbits compared with control rabbits while it was significantly (P < 0.05) decreased in aortic tissues of HFD rabbits compared with control rabbits with percentage normalized change of 73%. The total collagen was significantly (p < 0.01) decreased in aortic tissues of HFD rabbits compared with control rabbits with percentage normalized change of 73% which was supported by histological study.ConclusionsThese results suggest that percentage decrease in various Hyp fractions in aortic tissue of HFD rabbits are closely related to percentage decrease of collagen content in aortic tissues of HFD rabbits. These results also suggest that it may be possible to use the changes in various Hyp fractions in aortic tissues of rabbits as an important risk factor during the progression of atherosclerosis.

Absorption optical density as a diagnostic tool for indicating the toxicity of gold nanoparticles

Nanotechnology has recently emerged as a promising approach for treatment and diagnosis of a variety of diseases. The aim of this study was to evaluate the blood absorption spectra to assess bioaccumulation and toxic effects of 100 µl of 10 and 50 nm gold nanoparticles (GNPs) upon intraperitoneal administration in rats for periods of three and seven days. Healthy 30 male Wistar-Kyoto rats were individually caged and divided into control group (NG: n = 10), group 1 (A: infusion of 10 nm GNPs for three days; n = 5; B: infusion of 10 nm GNPs for seven days; n = 5) and group 2 (A: infusion of 50 nm GNPs for three days; n = 5; B: infusion of 50 nm GNPs for seven days; n = 5). Dose of 100 µl of 10 and 50 nm GNPs were administered intraperitonealy to the animals. The blood absorbance peaks for G1A, G1B, G2A and G2B significantly decreased compared with the control. The blood absorbance peaks for G1A significantly decreased compared with G1B; and G2A significantly decreased compared with G2B. This implies that G1A is highly reactive than G1B, and G2A is highly reactive than G2B. A significant decrease (p<0.05) in all blood absorbance peaks observed by the administration of 10 and 50 nm GNPs for periods of three and seven days compared with the control. For the same GNPs size, the accumulation of GNPs in the blood after the administration of GNPs for three days was greater than that for seven days. In addition to non-significant blood absorbance peak differences were observed with the different GNP sizes for the same period of administration of GNPs. This study suggests that the 10 nm GNPs are mostly up taken and accumulated by tissues which support the toxic effects of the smaller GNPs by tissues. However, the 50 nm GNPs are and highly accumulated in blood, suggesting the toxic effects of the larger GNPs by blood. Thus, the absorption optical density can be considered as a diagnostic tool indicating the bioaccumulation and toxicity effects of GNPs in the tissues of rats.

Effects of feeding periods of high cholesterol and saturated fat diet on blood biochemistry and hydroxyproline fractions in rabbits.

Hypercholesterolemia and hypertriglyceridemia are considered as important risk factors during the atherosclerotic process. The aim of the present investigation was to study the total cholesterol (TC), low-density lipoprotein cholesterol (LDLC), high density lipoprotein (HDL), triglyceride (TG), platelet levels and hydroxyproline fractions during the pathogenesis of atherosclerosis. For this purpose, twenty five 12-weeks, New Zealand white male rabbits, were purchased, individually caged, and divided into either control group or cholesterol-fed group. The control group (n = 10) was fed 100 g/day of normal diet, ORC-4 (Oriental Yeast Co. Ltd., Tokyo, Japan) for a period of 15 weeks. The cholesterol-fed group (n = 15) was fed a high cholesterol and saturated fat diet of ORC-4 containing 1% cholesterol plus 1% olive oil (100 g/day) for periods of 5 (group 1), 10 (group 2) and 15 (group 3) weeks. Blood sample from each animal was taken at the end of the experimental period for the biochemical analysis. The results of the present study showed that TC, LDLC, TG, HDLC and platelets were significantly (P < 0.01) increased in cholesterol-fed rabbits as compared with control rabbits. The serum hydroxyproline (Hyp) in rabbits belonging to group 1 showed no significant alteration when compared to control group. Group 2 rabbits showed a significant increase of 103% (P < 0.01) and 100% (P < 0.001) in free and protein—bound hydroxyproline fractions respectively when compared to control rabbits. However, there was no significant change in peptide—bound and total serum hydroxyproline levels as compared to the control group (P > 0.05). There was no significant (P > 0.05) decrease of free serum hydroxyproline in group 3 rabbits when compared to control rabbits. On the other hand, group 3 rabbits showed a significant increase in peptide-bound and protein- bound Hyp by 517% (P < 0.05) and 100% (P < 0.01) respectively when compared to control rabbits. However, total serum Hyp in group 3 rabbits showed no significant (P > 0.05) change when compared to control rabbits. These results suggest that feeding rabbits high cholesterol and saturated fat diet for feeding periods of 5, 10 and 15 weeks induced significant change in TC, LDLC, HDL, TG, platelet levels and various Hyp fractions in serum without any significant change in the total Hyp content.

Synergistic Effect of Quercetin and α-Lipoic Acid on Aluminium Chloride Induced Neurotoxicity in Rats

Objectives The present study was carried out to study the protective effects of quercetin and α-lipoic acid alone and in combination against aluminum chloride induced neurotoxicity in rats. Materials and Methods The study consisted of eight groups, namely, Group 1: control rats, Group 2: rats receiving aluminium chloride 7 mg/kg body weight intraperitoneal route (i.p) for two weeks, Group 3: rats receiving quercetin 50 mg/kg body weight i.p. for two weeks, Group 4: rats receiving quercetin 50 mg/kg body weight followed by aluminium chloride 7 mg/kg body weight i.p. for two weeks, Group 5: rats receiving α-lipoic acid 20 mg/kg body weight i.p. for two weeks, Group 6: rats receiving lipoic acid 20 mg/kg body weight followed by aluminium chloride 7 mg/kg body weight i.p. for two weeks, Group 7: rats receiving α-lipoic acid 20 mg/kg body weight and quercetin 50 mg/kg body weight i.p. for two weeks, and Group 8: rats receiving α-lipoic acid 20 mg/kg body weight and quercetin 50 mg/kg body weight followed by aluminium chloride 7 mg/kg body weight i.p. for two weeks. The animals were killed after 24 hours of the last dose by cervical dislocation. Results Aluminium chloride treatment of rats resulted in significant increases in lipid peroxidation, protein carbonyl levels, and acetylcholine esterase activity in the brain. This was accompanied with significant decreases in reduced glutathione, activities of the glutathione reductase, and superoxide dismutase. Pretreatment of AlCl3 exposed rats to either quercetin or α-lipoic acid also restored altered lipid peroxidation and superoxide dismutase to near normal levels. Quercetin or α-lipoic acid pretreatment of AlCl3 exposed rats improved the protein carbonyl and reduced glutathione, glutathione reductase, and acetylcholine esterase activities in rat brains towards normal levels. Combined pretreatment of AlCl3 exposed rats with quercetin and α-lipoic acid resulted in a tendency towards normalization of most of the parameters. Conclusions Quercetin and α-lipoic acid complemented each other in protecting the rat brain against oxidative stress induced by aluminium chloride.

EFFECT OF β-ARTEETHER TREATMENT ON ERYTHROCYTIC METHEMOGLOBIN REDUCTASE SYSTEM IN PLASMODIUM YOELII NIGERIENSIS INFECTED MICE

Background: The methemoglobin reductase system plays a vital role in maintaining the equilibrium between hemoglobin (Hb) and methemoglobin (MetHb) in blood. Exposure of red blood cells to an oxidative stress (pathological/physiological) may cause impairment in this equilibrium. Objective: The status of MetHb and the related reductase system was studied during Plasmodium yoelii nigeriensis (P. y. nigeriensis) infection and β-arteether treatment in mice. Methods: Mice were divided into four groups. Normal group, normal mice treated withβ-arteether, P. y. nigeriensis infected mice and P. y. nigeriensis infected mice treated with β-arteether. Results: The present investigation revealed a marked decrease in the activity of MetHb reductase, with concomitant rise in MetHb levels during P. y. nigeriensis infection in mice erythrocytes (P<0.001) as compared to normal mice. However, the activities of the associated enzymes viz., lactate dehydrogenase, glucose 6-phosphate dehydrogenase and glutathione reductase were found to be increased with progressive rise in parasitemia.β-Arteether treatment (12.5 mg/kg body weight) of infected mice (parasitemia 20–25%) from day 5 of post infection resulted in complete clearance of parasitemia on day 7 of post infection, which was accompanied by restoration of all the altered above mentioned indices to near normal levels as compared to infected mice (P<0.001). Conclusion: These results suggest that there is a marked impairment of methemoglobin and methemoglobin reductase system during P. y. nigeriensis infection in mice. β-Arteether treatment of infected mice resulted in complete clearance of parasitemia which also caused the restoration of methemoglobin and methemoglobin reductase system to near normal levels.