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Biomedical subjects

N M Hassan

Publications and source records attributed to N M Hassan.

8 recordsLinked to original sources
PubMed2006

Changes of antioxidants levels in two maize lines following atrazine treatments.

Growth and antioxidants levels of shoot of 10-d-old maize lines (Zea mays L. Hybrid 351 and Giza 2) differentially responded to atrazine treatment at the recommended field dose (RFD) during the following 20 d. Atrazine significantly reduced shoot fresh and dry weights but significantly accumulated H(2)O(2), lipid peroxides and carbonyl groups in Giza 2 during the whole experiment; an effect that prolonged with either elapse of time or increasing the herbicide dose. Meanwhile, ascorbic acid (AsA) and reduced glutathione (GSH) contents were significantly decreased along with significant inhibitions in activities of superoxide dismutase (SOD; EC 1.15.1.1), catalase (CAT; EC 1.11.1.6), ascorbate peroxidase (APX; EC 1.11.1.7), guaiacol peroxidase (GPX; EC 1.11.1.7), and glutathione-S-transferase (GST; EC 2.5.1.18). Similar responses were observed in Hybrid 351 only during the first 12 d, and seemed to be overcome thereafter. These findings indicate an induced oxidative stress in maize following atrazine treatments. Such state appeared to be counterbalanced in Hybrid 351 but continued in Giza 2 concluding Giza 2 as more susceptible to atrazine than Hybrid 351. Therefore, the differential susceptibility of Giza 2 to atrazine is related to deficiency in antioxidant levels.

Antioxidants↗
PubMed2000

Determinants of case fatality rates of meningococcal disease during outbreaks in Makkah, Saudi Arabia, 1987-97.

We studied case-fatality rates (CFRs) among cases of meningococcal disease (MCD) admitted to Makkah (Saudi Arabia) hospitals during the period 1988-97. Of 483 cases, 431 (89.2%) were due to strains of serogroup A, 31 (6.4%) to serogroup W135, 16 (3.3%) to serogroup C, and 5 (10%) to serogroup B. Eighty-one patients died (case fatality rate (CFR)) 16.8%, 95% CI 13.5%, 20.4%). The CFR in infections due to serogroup A strains was 14.8%, and for other serogroups it was 32.7% (95% CI 20.3%, 47.1%). The CFR of MCD due to N. meningitidis serogroup A increased steadily with age (P<0.05). Seeking first medical help at a foreign Hajj medical mission and being treated in a non-specialized hospital were associated with a higher case fatality rate.

Adolescent↗
PubMed2000

Quinolizidine alkaloids from Sophora alopecuroides.

A new matrine-type alkaloid, 7alpha-hydroxysophoramine (1), was isolated from the aerial parts of Sophora alopecuroides together with eight known alkaloids, 12beta-hydroxysophocarpine (2), sophoramine (3), 14beta-hydroxymatrine, matrine, sophoridine, sophocarpine, adenocarpine, and baptifoline. The structures of compounds 1-3 were confirmed through single-crystal X-ray diffraction analysis.

Alkaloids↗
PubMed1996

Analysis and purification of phorbol esters using normal phase HPLC and photodiode-array detection.

For the first time a normal-phase HPLC method using photodiode-array detection is described for the analysis and purification of phorbol esters. The use of the method is demonstrated with examples of 10 different tigliane and daphnane esters (TPA, DOPP, DOPPA, Sap A, Sap B, Sap C, Sap D, Thy A, Ro and Rx). Both analytical and semipreparative techniques were developed. The method has been used in the final purification of DOPP and Rx from plant extracts. The method can be employed in the areas of phytochemistry, biochemistry and pharmacology/toxicology, where small samples of the toxic materials are required for research.

Chromatography, High Pressure Liquid↗
PubMed1993

Molecular modelling of tumour-promoting and non-promoting diterpene esters and molecular co-ordinates of the potent irritant resiniferatoxin.

The lowest energy conformer of seventeen diterpenes, representing five different phorbol and daphnane diterpene nuclei, has been generated. TPA possessed the highest minimum free energy of these compounds; all other compounds possessed a lower minimum free energy. Compounds based on the resiniferonol nucleus possessed the lowest minimum free energy (9.4-16.6% of that of TPA). The molecular co-ordinates of the non-promoting but potent irritant resiniferatoxin (Rx) are also reported. These studies may be important in elucidation of the biochemical mechanisms of action of diterpene esters, including an understanding of the interactions of diterpene esters with the phorbol ester binding domain of the protein kinase C isoform family.

Carcinogens↗
PubMed1985

The pathology of the spleen in steroid-treated immune thrombocytopenic purpura.

The spleen is a central organ in the pathophysiology of immune thrombocytopenic purpura (ITP). Splenic lymphoid tissue synthesizes anti-platelet IgG, and splenic cordal macrophages destroy platelets coated with anti-platelet antibodies. The morphologic features of the spleen in this disease reflect this splenic function: hypertrophied lymphoid follicles with secondary germinal centers in the white pulp, with perivascular plasma cells in the red pulp and evidence of increased platelet phagocytosis in cords of the Billroth. Foamy macrophages and evidence of a variable degree of extramedullary hematopoiesis also have been noted. The authors have studied 17 spleens removed for therapeutic purposes in patients with proven ITP previously treated with varying amounts of corticosteroids. In all cases there was little or no morphologic evidence of follicular hyperplasia or plasmacytosis. However, platelet sequestration and phagocytosis were demonstrated easily in all cases, both in histologic sections and in touch imprints. The authors' findings indicate that morphologic evidence of lymphoid activation characteristic in spleens from patients with ITP usually is ablated by prior corticosteroid therapy but that the characteristic platelet sequestration and phagocytosis persists.

Adult↗