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Biomedical subjects

K M Hassan

Publications and source records attributed to K M Hassan.

16 recordsLinked to original sources
PubMed2001

Satellite 2 methylation patterns in normal and ICF syndrome cells and association of hypomethylation with advanced replication.

Mutation in the DNMT3B DNA methyltransferase gene is a common cause of ICF (immunodeficiency, centromeric heterochromatin, facial anomalies) immunodeficiency syndrome and leads to hypomethylation of satellites 2 and 3 in pericentric heterochromatin. This hypomethylation is associated with centromeric decondensation and chromosomal rearrangements, suggesting that these satellite repeats have an important structural role. In addition, the satellite regions may have functional roles in modifying gene expression. The extent of satellite hypomethylation in ICF cells is unknown because methylation status has only been determined with restriction enzymes that cut infrequently at these loci. We have therefore developed a bisulfite conversion-based method to determine the detailed cytosine methylation patterns at satellite 2 sequences in a quantitative manner for normal and ICF samples. From our sequence analysis of unmodified DNA, the internal repeat region analyzed for methylation contains an average of 17 CpG sites. The average level of methylation in normal lymphoblasts and fibroblasts is 69% compared with 20% in such cells from ICF patients with DNMT3B mutations and 29% in normal sperm. Although the mean satellite 2 methylation values for these groups do not overlap, there is considerable overlap at the level of individual DNA strands. Our analysis has also revealed a pattern of methylation specificity, suggesting that some CpGs in the repeat are more prone to methylation than other sites. Variation in satellite 2 methylation among lymphoblasts from different ICF patients has prompted us to determine the frequency of cytogenetic abnormalities in these cells. Although our data suggest that some degree of hypomethylation is necessary for pericentromeric decondensation, factors other than DNA methylation appear to play a major role in this phenomenon. Another such factor may be altered replication timing because we have discovered that the hypomethylation of satellite 2 in ICF cultures is associated with advanced replication.

Animals↗
PubMed2001

Ear, nose and throat manifestations of relapsing polychondritis in a child.

Relapsing polychondritis is a rare disorder, that can present initially to Otolaryngologists and can easily be overlooked due to its relative rarity and atypical initial symptoms and signs. Here we report on a 12-year-old schoolboy who presented initially with ear, nose and throat manifestations, including stridor, cough, hoarseness, sore throat and fever. The other clinical signs such as nasal tip, depression and softening of right auricle, developed subsequently. The clinical features, laboratory investigations, diagnostic criteria and treatment options were discussed with a brief review of literature.

Antirheumatic Agents↗
PubMed2001

Cerebral venous thrombosis in a patient of paroxysmal nocturnal haemoglobinuria following aplastic anaemia.

A young lady who had aplastic anaemia presented for cerebral venous thrombosis after five years of follow up. She was diagnosed to have paroxysmal nocturnal haemoglobinuria. She had received immunosuppressive therapy with methylprednisolone, cyclosporine-A, anti-lymphocyte globulin, danazol and pregnenolone. The relation between aplastic anaemia, paroxysmal nocturnal haemoglobinuria and cerebral venous thrombosis is discussed. The role of immunosuppressive therapy for aplastic anaemia in causation of paroxysmal nocturnal haemoglobinuria is reviewed.

Adult↗
PubMed2001

Disseminated tuberculosis with ocular tuberculoma and disseminated candidiasis in acquired immunodeficiency syndrome.

A 39 years man presented with painless progressive loss of vision and proptosis of left eye associated with constitutional symptoms. He was diagnosed to have acquired immunodeficiency syndrome (AIDS) with disseminated tuberculosis (TB) and invasive candidiasis. The proptosis was due to a retrobulbar mass. The uncommon occurrence of retrobulbar tuberculoma and invasive candidiasis is discussed and relevant literature is reviewed.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Allergic fungal rhinosinusitis: report of 4 cases from Saudi Arabia.

Allergic fungal rhinosinusitis is a newly recognized clinical entity of chronic rhinosinusitis. Over the past 3 years, 4 such patients were treated in our hospital. The clinical and pathological features of these 4 cases which merited the criteria for such diagnosis, are described. All the 4 cases had history of nasal polyps, asthma, or both with radiographical evidence of pansinusitis. Histologically, the thick greenish-brown inspissated material specimens which were collected and submitted to the laboratory showed, eosinophils, Charcot-Leyden crystals but no fungal elements were detected on routine hematoxylin and eosin sections and no tissue invasion was noted. However, scanty aspergillus hyphae were detected on sections stained with silver. All 4 cases grew Aspergillus flavus only from the swabs and no other fungi were seen and all were treated by surgical debridement, aeration, oral itraconazole with no steroids.

Adolescent↗
PubMed1997

Synthesis of some biologically active agents derived from thieno[2,3-d]pyrimidine derivatives.

The key compound 1-amino-8-iminocyclopenta[b]thieno[2,3-d]pyrimidine (5g) was prepared by reaction of 2-amino-3-cyano cyclopenta[b]thiophene (1) with triethyl orthoformate followed by cyclization with hydrazine hydrate in ethanol. Refluxing of 1 with triethyl orthoformate in the presence of acetic anhydride gave an unexpected product 2. while reaction with aromatic amines gave the condensation products 4a-c. Reaction of 5g with formic acid, other formate derivatives, ethoxymethylenemalononitrile and ethyl ethoxymethylenecyanoacetate gave the same product cyclopentathieno-[2,3-d]-1,2,4-triazolo[3,2-f]pyrimidine 6. Compound 7 was prepared by different methods. Treatment of 5g with dicarbonyl compounds gave the triazol derivatives 8-11. Reaction of 5g with phenyl isothiocyanate, carbon disulphide and ethyl chloroformate gave the corresponding derivatives 12-14, respectively. Condensation of 5g with some selected aromatic and heterocyclic aldehydes, acetone, N-acetyl isatin and isatin gave the condensation products 15a-e, 16-18, respectively in good yields. Many of the synthesized compounds were tested in vitro for their inhibitory activity against a variety of bacteria such as: Serratia rhodnii, Bacillus cereus, Staphylococcus citreus and Pseudomonas aeruginosa and fungi such as: Aspergillus flavus, Penicillium chrysogenum and Alternaria alternarta. Some compounds showed modest activity.

Anti-Bacterial Agents↗
PubMed1995

Some pharmacological studies on Artemisia herba-alba (Asso.) in rabbits and mice.

The aqueous extract of Artemisia herba-alba Asso. (Compositae) produced an initial hyperglycaemia which was followed by hypoglycaemia in normoglycaemic and alloxan-treated rabbits and mice. The extract (0.39 g/kg) significantly increased gastrointestinal transit time and the reaction time to thermal stimuli but had no effect on the activity of alkaline phosphatase or concentrations of creatinine and urea in plasma. Histopathological examination indicated mild hydropic degeneration in hepatocytes and proximal convoluted tubules. The duodenum showed mild oedema of the substantia of the mucosal propria. The plant extract showed weak antimicrobial activity.

Alloxan↗
PubMed1993

Ammonia-independent modifications of the background EEG signal and paradoxical enhancement of epileptic abnormalities in EEG after acute administration of valproate to epileptic patients.

The effects on the background quantitative EEG (power spectral analysis) and concentration of valproate in plasma were studied after single-dose (14.3-33.3 mg/kg) oral administration in 12 epileptic patients with generalized nonconvulsive or partial seizures. An increase of the amplitude of the background EEG (diffuse and preponderant on anterior scalp areas) and a decrease of the 12.5-32.0 Hz relative power (limited to the posterior electrode deviations) were observed; the increase in the EEG total power was paralleled by a definite increment in incidence of epileptic phenomena in the EEG. Both effects proved unrelated to shifts in vigilance or changes in the concentration of ammonia or serum glucose in plasma and confirm previous observations from superimposable study designs. These findings are qualitatively opposite to those observed during long-term treatment at comparable doses and are suggested to reflect a direct CNS action of acute administration of valproate.

Adolescent↗
PubMed1992

Placebo effects in standard human neuropharmacological studies: effects of physiological variations of blood glucose and ammonia concentration on the electrophysiology of the visual system.

The effects on retinal and cortical visual evoked phenomena of the stimulus intensity/spatial frequency and of the spontaneous, physiological blood glucose/ammonia fluctuations were investigated comparatively in a pilot study on young male volunteers. Flash ERG and flash OPs to 5 different stimulus intensities and pattern VECP to 3 spatial frequencies were recorded at 2-hour intervals during a standard acute pharmaco-EEG experimental session (8 h) with administration of placebo; glucose and ammonia blood concentration levels were assessed concomitantly. The effects of the stimulus intensity/spatial frequency were statistically defined for each amplitude/latency measure by nonlinear regression analysis and were removed by computing the residuals from the regression function, which were then tested separately versus the glucose/ammonia concentration by linear regression. Glucose/ammonia statistically significant effects on the visual system were detected at concentration levels within the range of normality and were representative of a nonnegligeable portion of the data overall variance. These effects were selective on retinal/cortical evoked phenomena and it is conceivable that physiological or pathological metabolic changes might account for a still underestimated source of individual variability in human neuropharmacological studies otherwise adequately controlled.

Adult↗
PubMed1991

Cryptosporidiosis among children attending the Maternity and Paediatrics Teaching Hospital, Wad Medani, Central Region, Sudan.

Modified Ziehl Neelson staining technique was used to identify Cryptosporidium species oocysts in stool specimens. Faecal samples from 166 children with diarrhoea and from a control of 95 children, were submitted for examination. 13 children from among those with diarrhoea and none from the control group were found to have Cryptosporidium species oocysts. The majority of these 13 positive children presented with abdominal pain, nausea, low grade fever and anorexia.

Animals↗