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Biomedical subjects

K Hassan

Publications and source records attributed to K Hassan.

At least 55 records · Page 3Linked to original sources
PubMed1992

Southeast Asian mitochondrial DNA analysis reveals genetic continuity of ancient mongoloid migrations.

Human mitochondrial DNAs (mtDNAs) from 153 independent samples encompassing seven Asian populations were surveyed for sequence variation using the polymerase chain reaction (PCR), restriction endonuclease analysis and oligonucleotide hybridization. All Asian populations were found to share two ancient AluI/DdeI polymorphisms at nps 10394 and 10397 and to be genetically similar indicating that they share a common ancestry. The greatest mtDNA diversity and the highest frequency of mtDNAs with HpaI/HincII morph 1 were observed in the Vietnamese suggesting a Southern Mongoloid origin of Asians. Remnants of the founding populations of Papua New Guinea (PNG) were found in Malaysia, and a marked frequency cline for the COII/tRNA(Lys) intergenic deletion was observed along coastal Asia. Phylogenetic analysis indicates that both insertion and deletion mutations in the COII/tRNA(Lys) region have occurred more than once.

Asia, Southeastern↗
PubMed1992

HLA-DRw52-associated DRB1 alleles: identification using polymerase chain reaction-amplified DNA, sequence-specific oligonucleotide probes, and a chemiluminescent detection system.

Polymerase chain reaction (PCR) primers were designed to specifically amplify exon 2 of the DRw52-associated DRB1 alleles for subsequent typing by sequence-specific oligonucleotide probe (SSOP) hybridization and chemiluminescent detection. The DRw52 DRB1 group, encoding 22 of the 44 W.H.O. designated DRB1 allelic products, was divided by differential PCR with two polymorphism-directed forward primers. Based on a polymorphism at codon 13, these forward primers separate the DRw52-associated alleles into subsets; one comprised of the alleles of DR3/DRw11/DRw6 and the other of DRw8/DRw12/DRB1*1404. The DRB1 alleles in the latter subset were then defined by SSOP hybridization to the amplified DNA. The preferential amplification also resulted in SSOP definition of 15 alleles in the DR3/DRw11/DRw6 subset but some DRw11/DRw13 heterozygous allelic combinations were still unresolved. Two reverse PCR primers specific for the polymorphism at codon 86 were used to obtain amplified material to which SSOP reactivity provided definitive identification of the ambiguous heterozygotes.

Adult↗
PubMed1992

Acute leukaemia in children--French-American-British (FAB) classification and its relation to clinical features.

A retrospective study of 45 patients of acute leukaemia in children (15 years age), in relation to FAB classification, is presented. Acute lymphoblastic leukaemias (ALL) were commoner than acute myeloid leukaemias (AML), with an ALL:AML ratio of 4.63:1. Amongst ALL, L1 was the most frequent type (59%), followed by L2 (35%) and L3 (5.4%), respectively. FAB types M2, M3, M4 and M5 were diagnosed in 2 patients each. An analysis of clinical features in relation to FAB classification is also presented.

Acute Disease↗
PubMed1991

Deletion in erythrocyte band 3 gene in malaria-resistant Southeast Asian ovalocytosis.

Southeast Asian ovalocytosis (SAO) is a hereditary condition that is widespread in parts of Southeast Asia. The ovalocytic erythrocytes are rigid and resistant to invasion by various malarial parasites. We have previously found that the underlying defect in SAO involves band 3 protein, the major transmembrane protein, which has abnormal structure and function. We now report two linked mutations in the erythrocyte band 3 gene in SAO: (i) a deletion of codons 400-408 and (ii) a substitution, A----G, in the first base of codon 56 leading to substitution of Lys-56 by Glu-56. The first defect leads to a deletion of nine amino acids in the boundary of cytoplasmic and membrane domains of band 3. This defect has been detected in all 30 ovalocytic subjects from Malaysia, the Philippines, and two unrelated coastal regions of Papua New Guinea, whereas it was absent in all 30 controls from Southeast Asia and 20 subjects of different ethnic origin from the United States. The Lys-56----Glu substitution has likewise been found in all SAO subjects. However, it has also been detected in 5 of the 50 control subjects, suggesting that it represents a linked polymorphism. We conclude that the deletion of codons 400-408 in the band 3 gene constitutes the underlying molecular defect in SAO.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1991

Nonhypercholesterolemic effects of a palm-oil diet in Malaysian volunteers.

The effects on serum lipids of diets prepared with palm olein, corn oil, and coconut oil supplying approximately 75% of the fat calories were compared in three matched groups of healthy volunteers (61 males, 22 females, aged 20-34 y). Group I received a coconut-palm-coconut dietary sequence; group II, coconut-corn-coconut; and group III, coconut oil during all three 5-wk dietary periods. Compared with entry-level values, coconut oil raised the serum total cholesterol concentration greater than 10% in all three groups. Subsequent feeding of palm olein or corn oil significantly reduced the total cholesterol (-19%, -36%), the LDL cholesterol (-20%, -42%%) and the HDL cholesterol (-20%, -26%) concentrations, respectively. Whereas the entry level of the ratio of LDL to HDL was not appreciably altered by coconut oil, this ratio was decreased 8% by palm olein and 25% by corn oil. Serum triglycerides were unaffected during the palm-olein period but were significantly reduced during the corn-oil period.

Adult↗
PubMed1991

Comparison between flowcytometry and immunoperoxidase staining for the enumeration of lymphocyte subsets.

Immunoperoxidase staining was compared with flowcytometry for the enumeration of lymphocyte subsets. The percentages obtained for peripheral blood lymphocytes using immunoperoxidase (CD3 = 76 CD4 = 27.9, B = 10.7 CD4/CD8 = 1.8) differed significantly from those obtained by flowcytometry (CD3 = 65.7 CD4 = 39.4, CD8 = 25.6, B = 16.7, HLA DR = 11.9 CD4/CD8 = 1.54) for certain subsets (CD3, CD4, B). There was no significant difference in lymphocyte subsets between children and adults using the same method. These differences are probably due to the different methods used to prepare lymphocytes for analysis. Other factors that should also be considered are the presence of CD4 antigen on monocytes and CD8 on natural killer cells.

Flow Cytometry↗
PubMed1990

Molecular defect of the band 3 protein in southeast Asian ovalocytosis.

BACKGROUND: Southeast Asian ovalocytosis is a form of hereditary elliptocytosis in which the red cells are rigid and resistant to malaria invasion. The underlying molecular defect is unknown. METHODS AND RESULTS: We studied the red cells of 54 patients with ovalocytosis and 122 normal controls. We found that ovalocytes contain a structurally and functionally abnormal band 3 protein, the principal transmembrane protein of red cells. The structural lesion of ovalocyte band 3 was revealed by limited proteolytic cleavage of the protein, which produced fragments of abnormal size that were derived from the cytoplasmic domain of the protein. The structural lesion was present in all the subjects with ovalocytosis but none of the controls. This region of band 3 serves as the principal binding site for the membrane skeleton, a submembrane protein network composed of ankyrin, spectrin, actin, and protein 4.1. The structural defect is dominantly inherited, being tightly linked with the inheritance of ovalocytosis (the probability of linkage is in excess of 10 million to 1). Ovalocyte band 3 bound considerably more tightly than normal band 3 to ankyrin, which connects the membrane skeleton to the band 3 protein. This tight binding of ovalocyte band 3 to the underlying skeleton containing ankyrin was directly confirmed in intact cells by the finding that ovalocyte band 3 had markedly reduced lateral mobility in the membrane. CONCLUSIONS: The red cells in Southeast Asian ovalocytosis carry a structurally and functionally abnormal band 3 protein. This molecular defect may underlie the increased rigidity of the red cells and their resistance to invasion by malaria parasites.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1990

Molecular characterization and nonradioactive detection of beta-thalassemia in Malaysia.

The spectrum of beta-thalassemia mutations in Malaysia has been determined in 45 beta-thalassemia chromosomes using dot blot hybridization of the polymerase chain reaction amplified DNA and direct DNA sequencing. Eleven different molecular defects, including those previously detected in Chinese, Asian Indians, and American blacks, and a novel frameshift mutation causing beta zero-thalassemia were detected. Since this novel mutation, a T deletion in codon 15 creates a new restriction site for EcoRII enzyme; the mutation could be detected by EcoRII digestion of the appropriate amplified fragment. The results of the present study provide additional information on the molecular heterogeneity of beta-thalassemia in this population. We also demonstrated the nonradioactive detection method of the beta-thalassemia mutation based upon the digoxigenin-labeled oligonucleotide probes.

Base Sequence↗
PubMed1990

Platelet function studies in women on oral contraceptive pills.

A study was conducted on a total of 100 women attending the Family Planning Clinic in Kuala Lumpur. 50 took combined low-dose estrogen and progesterone pills for a year or more and the other 50 used different methods of birth control. Platelet aggregation, ATP release, Thromboxane B2, and 6-keto-prostaglandin F1alpha estimations were made to evaluate the effect of oral contraceptives (OCs) on platelet function and prostanoid production. The results showed no significant differences in the parameters measured in the 2 groups investigated. These findings are comparable to those reported by other studies, suggesting relatively low risk, if any, of thrombosis in OC users.

Asia↗
PubMed1990

Hepatotoxicity to different antituberculosis drug combinations.

Hepatotoxicity to different combinations of anti-tuberculosis drugs containing, Rifampicin (R), Streptomycin (S), Isoniazid (H), Pyrazinamide (Z) and Myambutol (E) is described in 47 patients who completed 6 to 9 months therapy. Seven cases (15%) showed signs of toxicity and in 4 patients (8.5%) the drugs had to be withdrawn. Two patients developed hepatitis, one with jaundice and the other with fever and deranged liver functions, while others 2 developed severe hypersensitivity reactions. Burning palms, difficulty in micturition, itching and giddiness were complained of by one patient each, which settled in due course without recourse to withdrawal of drugs.

Antitubercular Agents↗
PubMed1990

Cytogenetic studies in women with primary amenorrhea.

Cytogenetic investigations were carried out on 117 women with primary amenorrhea who had been referred to our Genetics Laboratory by clinicians throughout Malaysia, after exclusion of other causes of the disorder. Thirty-six cases (31%) showed numerical or structural abnormalities of the sex chromosomes. These can be broadly classified into 4 main types, namely, presence of a Y chromosome (14%), X-chromosome aneuploidies (8%), structural anomalies of the X-chromosome (7%) and lastly, presence of a marker chromosome (2%). Mosaics constituted 17% of the abnormalities observed, always in association with a 45,X cell line. There was no observable correlation between the phenotype of the patients and their respective abnormal karyotypes. The aetiological role of sex chromosomal abnormalities in these amenorrheic women is discussed.

Adolescent↗
PubMed1989

The erythrocyte sedimentation rate, C-reactive protein, plasma fibrinogen and viscosity in chronic renal disease patients with infection.

The sensitivity of the C-reactive protein (CRP) measurement as an indicator for infection in patients with chronic renal disease was compared to that of ESR, fibrinogen and plasma viscosity measurements. The ESR, fibrinogen and plasma viscosity did not correlate with the presence of infection, whereas the CRP level was elevated in the majority of patients with infection/fever and decreased when fever subsided.

Adolescent↗
PubMed1988

Clinical, genetic and fertility studies of Indians with beta S-globin gene and the influence of Hb S on Plasmodium falciparum malaria infection.

Clinical studies were carried out on mild Indian sickle cell anaemia in Malaysia, and genetic and fertility studies were carried out on 101 families with and without sickle-cell haemoglobin (Hb S). The Indian sickle cell anaemia patients reached adulthood, and pregnancies and deliveries were uneventful without blood transfusion. There was no foetal wastage and the number of children produced was not significantly different from that in families without Hb S. 28 Indian patients hospitalized with Plasmodium falciparum malaria infection were also examined for their beta S genotype. P. falciparum malaria infection occurred much more frequently in individuals without Hb S than in Hb S carriers.

Adolescent↗