Biomedical subjects

M E Hassan

Publications and source records attributed to M E Hassan.

5 recordsLinked to original sources

PubMed2006

Redo transanal endorectal pull-through: a preliminary study.

The aim of this study is to evaluate the safety and efficacy of the redo transanal endorectal pull-through (TEPT) for patients with persistent symptoms after pull-through for Hirschsprung's disease (HD). Seven children were included in the study, their ages ranged from 2.5 to 6 years (four males and three females). They presented with persistent obstructive symptoms after pull-through for HD, which was remediated with redo TEPT. Indications were persistent constipation, anastomotic stricture unresponsive to dilatation with or without attacks of enterocolitis. Mean follow-up period was 12 months (ranged from 8 to 16 months). Obstructive symptoms were relieved in all patients with no soiling throughout the period of follow-up. Enterocolitis developed once in two patients who responded to conservative management after hospitalization. There were no deaths and anastomotic leakage, persistent stricture and cuff abscess did not develop in our series. EMG mapping of the external anal sphincter showed a good resting and powerful squeezing pressure curve. Redo TEPT is a useful alternative procedure for persistent symptoms of HD, and it appears to be safe and effective.

Anal Canal↗

PubMed1994

Synthesis of (2R,3R,4S)-2-hydroxymethylpyrrolidine-3,4-diol from (2S)-3,4-dehydroproline derivatives.

(2R,3R,4S)-2-Hydroxymethylpyrrolidine-3,4-diol (1,4-dideoxy-1,4-imino-D-ribitol) was synthesized in five steps from N-protected (2S)-3,4-dehydroproline methyl esters. The stereoselective reaction of osmium tetraoxide with dehydroproline derivatives gave high yields of (2S,3R,4S)-3,4-dihydroxyprolines (2,3-trans-3,4-cis-3,4-dihydroxy-L-prolines) accompanied by small amounts (< 15%) of the diastereomeric (2S,3S,4R)-3,4-dihydroxyprolines (2,3-cis-3,4-cis-3,4-dihydroxy-L-prolines). The mixture of the diastereomeric glycols was converted into the isopropylidene acetals, and the isomers separated efficiently on a preparative scale. The resulting protected (2S,3R,4S)-3,4-dihydroxyproline methyl ester was reduced (LiBH4) to the 2-hydroxymethylpyrrolidine and deprotected, resulting in the production of (2R,3R,4S)-2-hydroxymethylpyrrolidine-3,4-diol in high yield and in high purity. The 1H and 13C NMR signals of the product have been unambiguously assigned using two-dimensional NMR techniques, and the identity of the title pyrrolidine confirmed by comparisons of its spectra with those reported for the authentic material.

Antiviral Agents↗

PubMed1988

A case of African histoplasmosis from Sudan.

The first authentic case of African histoplasmosis from the Sudan is reported. The patient came from Dindir, along the southern part of the Blue Nile River. He had cutaneous and visceral leishmaniasis as well as the cutaneous form of African histoplasmosis. The latter was proved by culture and histopathology to be due to Histoplasma duboisii. The fungus was confined to the skin. H. duboisii may be more prevalent, and further studies in Dindir area are needed.

Adult↗

PubMed1986

Isolation and characterization of nitrogenase-derepressed mutant strains of cyanobacterium Anabaena variabilis.

A positive selection method for isolation of nitrogenase-derepressed mutant strains of a filamentous cyanobacterium, Anabaena variabilis, is described. Mutant strains that are resistant to a glutamate analog, L-methionine-D,L-sulfoximine, were screened for their ability to produce and excrete NH4+ into medium. Mutant strains capable of producing nitrogenase in the presence of NH4+ were selected from a population of NH4+-excreting mutants. One of the mutant strains (SA-1) studied in detail was found to be a conditional glutamine auxotroph requiring glutamine for growth in media containing N2, NO3-, or low concentrations of NH4+ (less than 0.5 mM). This glutamine requirement is a consequence of a block in the assimilation of NH4+ produced by an enzyme system like nitrogenase. Glutamate and aspartate failed to substitute for glutamine because of a defect in the transport and utilization of these amino acids. Strain SA-1 assimilated NH4+ when the concentration in the medium reached about 0.5 mM, and under these conditions the growth rate was similar to that of the parent. Mutant strain SA-1 produced L-methionine-D,L-sulfoximine-resistant glutamine synthetase activity. Kinetic properties of the enzyme from the parent and mutant were similar. Mutant strain SA-1 can potentially serve as a source of fertilizer nitrogen to support growth of crop plants, since the NH4+ produced by nitrogenase, utilizing sunlight and water as sources of energy and reductant, respectively, is excreted into the environment.

Ammonia↗

PubMedDate not supplied

Two cases of ocular leishmaniasis.

Two cases of cutaneous leishmaniasis with ocular involvement are presented. The diagnostic difficulty, the possible complications and the importance of a correct diagnosis of such cases is discussed in the light of the cases presented and of previous similar case reports.

Adult↗