Tarek M. Mohamed

Oxidative stress and thyroid hormones in patients with liver diseases

BACKGROUND The liver metabolizes the thyroid hormones and regulates their systemic endocrine effects so liver disease could affect thyroid hormone metabolism. Oxidative stress could play a role in the pathogenesis and progression of liver diseases. The objective of this study was to investigate serum levels of oxidative stress and antioxidant in liver diseases as prognostic markers and know the importance of these antioxidants level in relation to thyroid hormones. METHODS Serum nitric oxide (NO), malondialdehyde (MDA) and triiodothyronine (T(3)), thyroxine (T(4)), thyroid stimulating hormone (TSH), apolipoprotein-1 (APOA1) levels and erythrocyte reduced glutathione (GSH) level and glutathione peroxidase (GSHPx) and glutathione reductase (GR) activities were determined in 20 control subjects, 13 patients with non-alcoholic steatohepatitis (NASH), 18 patients with chronic HCV, 17 patients with compensated cirrhotic HCV and 42 patients with decompensated cirrhotic HCV. RESULTS Cirrhotic patients with HCV had higher NO and MDA levels while lower T(3) and erythrocyte GSH levels, and GSHPx activity than the chronic. Serum T(3) showed negative correlation with serum NO and MDA whereas positive correlation with APOA1, GSH, and GSHPx in cirrhotic patients with HCV. CONCLUSION The measurement of the total T(3), NO, MDA, GSH reduced and GSHPx as biomarkers for liver diseases might be a beneficial tool, helping in monitoring the state of liver disease patients.

Distribution of lipases in the Gramineae. Partial purification and characterization of esterase from Avena fatua

Abstract The activity levels of esterase, lipid acylhydrolase and lipase were quantitatively screened in 23 species and cultivars of Gramineae. Their activity levels expressed as units g −1 seeds, were found to range from 10 to 123 for esterase, 0.28 to 7.67 for lipid acylhydrolase and 13.1 to 93.9 for lipase. Avena fatua , one of the grass species, exhibited the highest levels of esterase and lipase and could be potentially a good starting material for preparation of lipases. A. fatua esterase has been partially purified and characterized. Four isoenzymes, EI, EII, EIII and EIV, were separated by ion exchange chromatography. Esterases EII and EIII had Km values of 0.52 and 0.38 mM and a pH optimum at 9.0 with half maximal activities at pHs 8.5, 10 and 8, 10.5, respectively. Esterases EII and EIII had optimum activities at temperatures of 75°C and 65°C with activation energies of 3.3 and 4.3 kcal mol −1 , respectively. The enzymes were thermally stable as esterases EII and EIII retaining 39% and 23% of their activities at 90°C, respectively. Esterases EII and EIII were stimulated by Ba 2+ and Ca 2+ but were inhibited by Mn 2+ and Zn 2+ . A. fatua esterases exhibited optimum storage stability and were stable at high temperatures and alkaline pH. They possessed high affinity toward substrate and were resistant to inhibition by most divalent cations that were examined. These are important properties when considering the industrial application of these enzymes.

Studies on antiretroviral drug concentrations in breast milk: validation of a liquid chromatography-tandem mass spectrometric method for the determination of 7 anti-human immunodeficiency virus medications.

Studying the pharmacokinetics of antiretroviral drugs in breast milk has important implications for the health of both the mother and the infant, particularly in resource-poor countries. Breast milk is a highly complex biological matrix, yet it is necessary to develop and validate methods in this matrix, which simultaneously measure multiple analytes, as women may be taking any number of drug combinations to combat human immunodeficiency virus infection. Here, we report a novel extraction method coupled to high-performance liquid chromatography and tandem mass spectrometry for the accurate, precise, and specific measurement of 7 antiretroviral drugs currently prescribed to infected mothers. Using 200 μL of human breast milk, simultaneous quantification of lamivudine (3TC), stavudine (d4T), zidovudine (ZDV), nevirapine (NVP), nelfinavir (NFV), ritonavir, and lopinavir was validated over the range of 10-10,000 ng/mL. Intraday accuracy and precision for all analytes were 99.3% and 5.0 %, respectively. Interday accuracy and precision were 99.4 % and 7.8%, respectively. Cross-assay validation with UV detection was performed using clinical breast milk samples, and the results of the 2 assays were in good agreement (P = 0.0001, r = 0.97). Breast milk to plasma concentration ratios for the different antiretroviral drugs were determined as follows: 3TC = 2.96, d4T = 1.73, ZDV = 1.17, NVP = 0.82, and NFV = 0.21.

Immobilization and characterization of inulinase from Ulocladium atrum on nonwoven fabrics

Ulocladium atrum inulinase was immobilized on different composite membranes composed of chitosan/nonwoven fabrics. Km values of free and immobilized U. atrum inulinase on different composite membranes were calculated. The enzyme had optimum pH at 5.6 for free and immobilized U. atrum inulinase on polyester nonwoven fabric coated with 3% chitosan solution (PPNWF3), but optimum pH was 5 for immobilized U. atrum inulinase on polyester and polypropylene nonwoven fabrics coated with 1% chitosan solution. The enzyme had optimum temperature at 40°C for immobilized enzyme on each of polyester and polypropylene composite membranes coated with 1% chitosan, while it was 50°C for free and immobilized enzyme on polypropylene nonwoven fabric coated with 3% chitosan solution. Free U. atrum inulinase was stable at 40°C but thermal stability of the immobilized enzyme was detected up to 60°C. Reusability of immobilized enzyme was from 38 to 42 cycles of reuse; after this, the immobilized enzyme lost its activity completely. In conclusion, immobilized U. atrum inulinase was considerably more stable than the free enzyme, and could be stored for extended periods.

Anti-diabetic activity of Holothuria thomasi saponin

BACKGROUND Diabetes mellitus represents a global health problem. It characterized by hyperglycemia that induces oxidative stress leading to a generation of free radicals. A wide variety of natural products in plants and other marine animals represent antioxidant activity and other health benefits like those of sea cucumber. Therefore, this study aimed to investigate the antidiabetic activity of glycosidic compound - saponin - derived from the Egyptian sea cucumber, Holothuria thomasi. MATERIALS AND METHODS Saponin has been extracted from the Egyptian sea cucumber and confirmed by hemolysis, Salkowski tests, FT/IR, UV and GC-MS analysis. Eighty white female albino rats were divided into four equal groups. The first two groups of rats; control normal and control normal saponin-treated groups. The last two groups which were made diabetic by intraperitoneal injection of streptozotocin had one diabetic control and the other diabetic group that got 300mg/kg B.wt. of saponin extract after Thirty-five days after diabetes induction and lasted for six weeks. RESULTS The functional group of saponin extract which established with FT/IR spectroscopy demonstrated the presence of saponin in the extracted materials as shown in the peak of the functional group in relevance to the standard one. The UV spectra revealed that λmax of saponin extract was 282nm which in accordance to the standard saponin. Also, GC-MS analysis indicated that the aglycone part of saponin was methyl esters of octadecanoic acid. Saponin extract significantly decreased serum glucose, α-amylase activity, adiponectin, IL-6, TNF-α concentrations and liver L-MDA. However, serum insulin and liver glycogen levels were significantly increased as compared with the diabetic non-treated groups. The histopathological results supported that saponin extract markedly reduced the degenerative change in β-cells. CONCLUSIONS This study, therefore, depicts that the Egyptian Holothuria thomasi, sea cucumber saponin as a hypoglycemic agent with the potential to normalize aberrant biochemical parameters and preserved the normal histological architecture of the islets cells of pancreatic tissues.

Nitric Oxide Synthase and Oxidative Stress: Regulation of Nitric Oxide Synthase

Nitric oxide has been found to play an important role as a signal molecule in many parts of the organism as well as a cytotocic effector molecule of nonspecific immune response. Nitric oxide is very important functions both in helminthes and mammalian hosts. Nitric oxide may react with proteins and nucleic acids. In addition to binding to heme groups, e.g. of guanylate cyclase, hemoglobin, and cytochrome C oxidase, NO may react with nucleophilic centers like sulfur, nitrogen, oxygen and aromatic carbons. The prime target for covalent binding of NO to a functional groups in proteins under physiological condition in the presence of oxygen are SH groups. The intra-mitochondrial reaction of NO with superoxide anion yields peroxynitrite, which irreversibly modifies susceptible targets within the mitochondria, inducing oxidative and/or nitrative stresses. The signal molecule of NO is synthesized by constitutive nitric oxide synthase (cNOS). The killer molecule NO is synthesized by inducible NOS (iNOS). There is no signal or killer NO – it depends on the environments and partners involved – be very careful in that. Yes, the production is regulated in different ways. Inducible NOS is induced by numerous inflammatory stimuli, including endotoxin, cytokines and excretory/secretory products (ESP) of helminthes. ESP directly interact with the immune system and modulate host immunity. Nitric oxide is a highly reactive and unstable free radical gas that is produced by oxidation of Larginine by oxygen and NADPH as electron donor to citrulline mediated by a family of homodimer named nitric oxide synthase. In addition to Larginine-NO pathway, L-arginine is also metabolized to L-ornithine and urea by arginase enzyme. A side from blocking NO synthesis by depleting the cell of substrate for NOS, the arginase-mediated removal of Larginine inhibits the expression of inducible NOS (iNOS) by repressing the translation as well as the stability of iNOS protein. Furthermore, arginase may inhibit iNOS-mediated NO production through the generation of urea.

Potential biodegradation of crude petroleum oil by newly isolated halotolerant microbial strains from polluted Red Sea area.

Two microbial isolates from oil polluted Red Sea water in Egypt, designated as RS-Y1 and RS-F3, were found capable of degrading Belayim mix (BX) crude oil. Strains RS-Y1 and RS-F3 were assigned to the genera Lipomyces tetrasporus and Paecilomyces variotii based on their morphological and physiological characteristics. Both isolates were compared for the biodegradation of crude petroleum-oil hydrocarbons in basal salt medium supplemented with 5% (w/v) of BX-crude oil. Gas chromatography profile showed that the biodegradation of total petroleum hydrocarbons (TPHs) inoculated with L. tetrasporus (68.3%) and P. variotii (58.15%) along with their consortium (66%) significantly reduced TPHs levels as compared to the control after 30days. L. tetrasporus (44.5%) was more effective than P. variotii strain (32.89%) in reducing the unresolved complex mixtures (UCM) content from the medium. Both isolates exhibited a strong growth over a wide range of salinity (5-45g/L NaCl).

Effects of tramadol, clonazepam, and their combination on brain mitochondrial complexes

The present study is an unsubstantiated qualitative assessment of the abused drugs—tramadol and clonazepam. The aim of this study is to evaluate whether the effects of tramadol, clonazepam, and their combination on mitochondrial electron transport chain (ETC) complexes were influential at therapeutic or at progressively increasing doses. The study comprised of a total of 70 healthy male rats, aged 3 months. According to the drug intake regimen, animals were divided into seven groups: control, tramadol therapeutic, clonazepam therapeutic, combination therapeutic, tramadol abuse, clonazepam abuse, and combination abuse group. At the end of the experiment, brain mitochondrial ETC complexes (I, II, III, and IV) were evaluated. Histopathological examinations were also performed on brain tissues. The results showed that groups that received tramadol (therapeutic and abuse) suffered from weight loss. Tramadol abuse group and combination abuse group showed significant decrease in the activities of I, III, and IV complexes but not in the activity of complex II. In conclusion, tramadol but not clonazepam has been found to partially inhibit the activities of respiratory chain complexes I, III, and IV but not the activity of complex II and such inhibition occurred only at doses that exceeded the maximum recommended adult human daily therapeutic doses. This result explains the clinical and histopathological effects of tramadol, such as seizures and red neurons (marker for apoptosis), respectively.

Effects of phytate on thyroid gland of rats intoxicated with cadmium.

Cadmium (Cd) is one of the most dangerous occupational and environmental toxins. The objective of the present study is to examine the potential prophylactic effects of phytic acid (PA) on thyroid hormones of male rats intoxicated with Cd. The male albino rats were divided into five groups: group I (control) was fed with the basal diet, group II was intoxicated with Cd in drinking water, groups III, IV, and V were intoxicated with Cd in drinking water and fed with the diet containing 3.5, 7, and 10 g of PA/kg, respectively. The results indicated that the serum calcium, iron (Fe), and total Fe binding capacity levels and serum T3 and T4 in Cd-treated rats of group II were decreased when compared with the control group, while PA-administered groups with Cd showed a significant improvement when compared with the Cd-treated rats only. Serum thyroid stimulating hormone (TSH) level was significantly increased in Cd-treated rats compared with the control group, while the addition of PA in diet decreased the high levels of TSH. These results indicated a prophylactic effect of PA against Cd-induced toxicity in rats.

Purification and characterization of aspartate aminotransferase from developing embryos of the camel tick Hyalomma dromedarii.

Aspartate transaminase (AST) activity in the camel tick Hyalomma dromedarii was followed throughout embryogenesis. During purification of AST to homogeneity, ion exchange chromatography lead to four separate forms (termed I, II, III and IV). AST II with the highest specific activity was pure after chromatography on Sephacryl S-300. The molecular mass of AST II was 52 KDa for the native enzyme, composed of one subunit of 50 KDa. AST II had a Km value of 0.67 mM for α-ketoglutarate and 15.1 mM for aspartate. AST II had a pH optimum of 7.5 with heat stability up to 50°C for 15 min. The enzyme was activated by MnCl2, and inhibited by CaCl2, MgCl2, NiCl2, and ZnCl2.