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H J Hassan

Publications and source records attributed to H J Hassan.

9 recordsLinked to original sources
PubMed1992

PCR analysis of HIV-1 sequences and differential immunological features in seronegative and seropositive haemophiliacs.

We have compared the immunological features of two matched groups of seronegative and seropositive haemophilia A individuals. Both groups were exposed from 1981 to 1985 to comparable amounts and batches of FVIII concentrates not subjected to virus inactivation procedures, and had therefore a 100% probability of receiving HIV-contaminated material. The presence of proviral HIV-1 sequences was evaluated by PCR in the DNA from peripheral blood lymphocytes and/or monocytes. After hybridization with specific probes, DNA from all seropositive haemophiliacs revealed HIV sequences; no HIV sequences were observed from the DNA of seronegative patients, even after two rounds of amplification, thus suggesting that these patients were not affected by a latent HIV infection. Seronegative/PCR- and seropositive/PCR+ patients showed a normal and reduced number of CD4+ lymphocytes, and a slight and marked increase of CD8+ cells respectively. Activated T cells expressing the HLA-DR antigen were elevated in both groups. Interestingly, a significant reduction of circulating CD56+/CD3- NK lymphocytes was observed only in seropositive haemophiliacs, whereas NK lymphocytes with CD56+/CD3+ phenotype were within normal levels in both groups. In seropositive patients no correlation was found between the number of CD4+ and CD56+/CD3- lymphocytes. The marked reduction of CD56+/CD3- lymphocytes observed in seropositive haemophiliacs in addition to the CD4+ cell depletion may represent a key pathogenetic factor which facilitates the onset and/or the progression of HIV-1 infection in haemophiliacs, and is related to the capacity of HIV to infect NK cells.

Antigens, CD↗
PubMed1990

Blood coagulation factors in human embryonic-fetal development: preferential expression of the FVII/tissue factor pathway.

The expression of a number of blood coagulation factors (F) (FX, FIX, FVIII, FVII, alpha-, beta-, gamma-fibrinogen chains, protein C, and antithrombin III [AT III]) was analyzed at RNA and protein level in 5- to 10-week-old human embryos and fetuses. FX, FIX, and FVII were also analyzed at protein level. Total and poly(A)+ RNA, extracted from embryonic-fetal (FL) and adult liver (AL), were analyzed by dot and Northern blot hybridization with specific cDNA probes. The results indicate that: (1) the size of the messenger RNAs of these factors is equivalent in FL and AL; (2) in the 5- to 10-week period, their abundance in FL increases from 30% to 50% of the adult level except for FIX (from 2% to 10%) and FX (always 100% of the adult value). Western blot analysis of FIX, FX, and FVII in 5- to 10-week soluble liver proteins and 6- to 8-week plasma showed a low level of FIX versus a higher concentration of both FVII and FX, when compared with corresponding adult values, ie, a liver protein level of 10% versus 100% and a plasma concentration level of 10% versus 40%. Although little is known so far on the activity and the functional role of the clotting factors in early human ontogenic development, these studies suggest an activation of FX via the FVII/tissue factor activity rather than the FIXa/FVIIIa phospholipid complex in human embryonic and early fetal life.

Blood Coagulation Factors↗
PubMed1990

Carrier detection for hemophilia B: evaluation of multiple polymorphic sites.

DNA analysis was performed in families with hemophilia B. Restriction fragment length polymorphisms (RFLPs) produced by endonucleases Taql, Xmnl, and Ddel were studied by two factor IX genomic probes, F9(VIII) and F9(XIII). Fifty-seven subjects from ten families were investigated; of them, 31 were carriers (11 obligate and 20 potential). Of the potential carriers, ten displayed laboratory features allowing for a phenotypic diagnosis of heterozygosity. Segregation analysis of the markers was informative in 19/20 potential carriers, which belong to nine of the ten studied families. Among the potential carriers, Taql allowed the carriership assessment in 15 (78.9%), Xmnl in 15 (94.7%), and Ddel in two (10.4%). Diagnosis was not possible in one family since a homozygosity in the key individuals with all the employed enzymes (Taql, Xmnl, Ddel, + BamHI) was found. Hemophilia B syndrome in two families likely results from a new mutation. In one family, a first-trimester prenatal diagnosis was performed. The use of RFLP analysis allowed us to improve genetic counseling as compared with the phenotypic evaluation by clotting factor assays. Indeed, evaluation of RFLP increased by 26% the carriership assessment of the potential carriers of the hemophilia B trait.

DNA Probes↗
PubMed1988

Factor X Roma: a congenital factor X variant defective at different degrees in the intrinsic and the extrinsic activation.

A factor X molecular variant was identified in a 13-year-old girl affected by a bleeding tendency. Factor X antigen levels and activation by Russel's viper venom (tested both by clotting and amidolytic assays) were normal. Factor X crossed immunoelectrophoresis was found to be identical to that of the control plasma. Factor X functional activity was low (3% of the normal) if tested by PTT-derived assays, whereas it was found at intermediate levels (about 30-50% of the normal) if measured by prothrombin time-derived assays. The defect in the extrinsic activation was more clearly disclosed using as activating agent thromboplastin from ox brain. The factor X of the patient was completely adsorbed by aluminum hydroxide. The parents of the propositus (first degree cousins) showed factor X functional levels compatible with a condition of heterozygosity for the abnormality. This factor X molecular variant appears different from the other ones so far described and was named 'Factor X Roma'.

Adolescent↗
PubMed1988

Multiple polymorphic sites in factor X locus.

The structure of factor X (FX) gene was analyzed in five FX deficient pedigrees with four different variants of the disease, as well as in 50 normal subjects. Genomic DNA from the deficient patients and the normal controls was digested with 12 restriction endonucleases and hybridized with a FX cDNA probe. The results seemingly exclude gross gene deletions or rearrangements in the deficient patients. A variety of polymorphic sites (ie, EcoRI, HindIII, PstI, PvuII, TaqI) was observed within the FX locus and their relative frequency was established. Intriguingly, a highly polymorphic region for the PvuII endonuclease was identified and located approximately 3 kilobases (kb) from the last 3' exon. These polymorphisms allowed us to analyze the allelic segregation in a FX deficient family and to identify a homozygous subject.

Adult↗
PubMed1987

Hereditary thrombophilia: identification of nonsense and missense mutations in the protein C gene.

The structure of the gene for protein C, an anticoagulant serine protease, was analyzed in 29 unrelated patients with hereditary thrombophilia and protein C deficiency. Gene deletion(s) or gross rearrangement(s) was not demonstrable by Southern blot hybridization to cDNA probes. However, two unrelated patients showed a variant restriction pattern after Pvu II or BamHI digestion, due to mutations in the last exon: analysis of their pedigrees, including three or seven heterozygotes, respectively, with approximately 50% reduction of both enzymatic and antigen level, showed the abnormal restriction pattern in all heterozygous individuals, but not in normal relatives. Cloning of protein C gene and sequencing of the last exon allowed us to identify a nonsense and a missense mutation, respectively. In the first case, codon 306 (CGA, arginine) is mutated to an inframe stop codon, thus generating a new Pvu II recognition site. In the second case, a missense mutation in the BamHI palindrome (GGATCC----GCATCC) leads to substitution of a key amino acid (a tryptophan to cysteine substitution at position 402), invariantly conserved in eukaryotic serine proteases. These point mutations may explain the protein C-deficiency phenotype of heterozygotes in the two pedigrees.

Amino Acid Sequence↗
PubMed1985

Intragenic Factor IX restriction site polymorphism in hemophilia B variants.

This study includes 47 normal subjects and 25 hemophilia B patients without inhibitor(s), showing different factor IX coagulant activity and antigen levels. Genomic DNA, digested with various restriction endonucleases, was hybridized with two different factor IX probes, ie, the cDNA and the subgenomic probe for the intragenic TaqI polymorphic site. cDNA restriction patterns suggest absence of gross rearrangements and/or deletions in all hemophilic patients. The frequency of the X chromosome bearing the TaqI polymorphic site is 0.32 +/- 0.09 in hemophilic subjects v 0.36 +/- 0.06 in normal control subjects, the latter value being comparable to that reported for the normal British population. No association between this polymorphism and hemophilia B variants has been observed, thus indicating that a wide spectrum of mutations underlies this blood-clotting disorder and particularly each of its variants.

Cloning, Molecular↗
PubMed1985

Hemophilia B with inhibitor: molecular analysis of the subtotal deletion of the factor IX gene.

The structure of factor IX gene was analyzed in a hemophilia B patient with inhibitor. Genomic DNA, digested with a variety of restriction endonucleases, was hybridized with the cDNA and various genomic factor IX probes. A large subtotal deletion of the gene was observed. The borders of the deletion span from a approximately 125 nucleotide region within the last exon to an unknown domain at least 7.5 kb upstream from the first exon: it thus involves approximately 33 kb of the factor IX locus. The abnormal gene was inherited by the daughter of the propositus, who showed both the normal and the deleted allele.

Chromosome Deletion↗