Spectrum of inherited bleeding disorders from Western India.

OBJECTIVE: The study was undertaken to assess the magnitude and diversity of different bleeding disorders in Western India. MATERIALS AND METHODS: 768 cases referred to our Institute for evaluation of an underlying bleeding diathesis were investigated appropriately to detect the cause of the abnormal hemostatic function. RESULTS: 630 patients were diagnosed to have hereditary bleeding diathesis. Amongst these, 598 patients had a coagulation disorder while only 32 patients had a platelet function abnormality. Amongst the coagulation disorders, hemophilia A (70.5%) was the most common disorder followed by hemophilia B (14%) and VWD (10.8%). Glanzman's thrombasthenia (84.3%) was the most common platelet function disorder followed by Bernard-Soulier syndrome (12.5%). Some rare disorders have also been diagnosed. CONCLUSION: In spite of their apparent rarity, India has a substantial number of cases of inherited bleeding disorders. A large number of these patients is referred to many tertiary care institutions. It is therefore desirable that district hospitals must develop their laboratories to detect most of these disorders so that the patients need not travel long distances to get an appropriate diagnosis and proper management. All 1st degree female relatives of severe and moderate hemophilia must get factor assays done because some of them may be vulnerable to post-procedural or post-traumatic bleeding.

Development of inhibitors in patients with haemophilia from India.

Four hundred and seven patients (352 haemophilia A and 55 haemophilia B) were investigated for the presence of factor VIII and IX inhibitors. Twenty-four out of 292 severe and two out of 36 moderate haemophilia A patients showed the presence of inhibitors. The mean age at development of inhibitors was 17.7 years (range 6-52 years). In 12 patients the inhibitors were detected due to suboptimal response to factor replacement therapy (symptomatic) and in the remaining 14 patients the inhibitors were detected during the routine screening of the patients' samples for inhibitors. They had, however, responded well to the usual doses of factor concentrates and there was no suspicion in these patients that they had developed an inhibitor (asymptomatic). There were two families in which the inhibitors were detected in more than one family member. The level of inhibitors in symptomatic patients ranged from 2.2 Bethesda units (BU) mL(-1) to 460.6 BU mL(-1), and in asymptomatic patients it ranged from 0.8 BU mL(-1) to 3.2 BU mL(-1). The inhibitors persisted in all patients except one, who developed an inhibitor postoperatively for a brief period of 3 months. All these patients were followed up from first factor exposure and were tested for inhibitors at least twice a year. The mean number of exposure days before they developed inhibitors was 47.5 exposure days (range 17-98 exposure days). No inhibitors appeared after more than 100 exposure days in any of the patients. When 50 consecutive patients were investigated for intron 22 inversions of the factor VIII gene, 17 patients were found to be positive for inversions (10 proximal inversion; seven distal inversion) out of whom four patients developed inhibitors, three patients belonging to the same family. Out of 35 haemophilia B patients, only one patient developed an inhibitor. The overall prevalence of inhibitors was thus 8.2%, which is similar to the reports from western countries, prior to the introduction of highly purified factor concentrate therapy.

Combined factor V and VIII deficiency in Indian population.

The clinical and haematological heterogeneity in cases of the rare combined factor V and VIII deficiency has not been reported so far from India. Nine such cases belonging to five unrelated families have been analysed in the present study for the various haematological and clinical parameters. A very mild clinical presentation is seen in all these cases. The clinical manifestations, however, do not correlate with the plasma levels of these factors.

Organothallium(III) reagents for modification of biomacromolecules: irreversible labelling of phosphoglycerate kinase from rabbit muscle.

Organothallium(III) reagents, by analogy with organomercurials, have been found to rapidly label phosphoglycerate kinase from rabbit muscle. By use of a radio-labelled version of p-methylphenylthallium(III) bis-trifluoroacetate (MPT) the inhibition was shown to be irreversible by the criterion of gel filtration desalting. The rate of labelling was shown to depend on the temperature, enzyme and thallium reagent concentrations, and the presence or absence of the various substrates of the enzyme. The structure and oxidation state of the thallium reagent used affected the extent of modification by the compounds MPT, o-carboxyphenylthallium(III) bis-trifluoroacetate, thallic trifluoroacetate and thallous acetate. A number of pieces of evidence implicate cysteine residues in the labelling, including changes in the free thiol titre of the enzyme on thalliation, model studies on the interaction of thiols (e.g. glutathione) with thallium(III) and thallous materials, the lack of inactivation of phosphoglycerate kinase from yeast (which has only one thiol residue distant from the active site), and the partial restoration of enzymic activity by treatment of thalliated enzyme with sulphydryl reducing agents. Substrate protection studies showed that modification of rabbit muscle phosphoglycerate kinase by MPT was fully prevented by 3-phosphoglycerate and partially by MgATP. The latter protected only against the fast phase of thallic modification, the slower phase being unaffected. The presence of MgADP potentiated the labelling by MPT. No evidence of an MgADP-induced conformational change in the enzyme could be obtained from fluorescence or circular dichroic spectroscopies, although changes of the native spectra were noted on thalliation by MPT alone. The cross-linking potential of these arylthallium(III) reagents is discussed along with conformational changes required to trigger the hinge-movement between the N- and C-domains of the protein.

Organothallium(III) reagents for modification of biomacromolecules: interaction of thallium derivatives with transfer RNA.

As an extension of work on the inhibition of enzymes by arylthallium(III) reagents, the thallium analogues of the organomercurials, we have studied the interactions of these molecules with transfer RNA. In contrast to thallous acetate, thallium(III) derivatives (thallic trifluoroacetate, p-methylphenylthallium(III) bis-trifluoroacetate (MPT) and o-carboxyphenylthallium(III) bis-trifluoroacetate) bound to Escherichia coli tRNA. The interaction was fully reversible upon Sephadex G-25 gel filtration, and binding constants and stoichiometries were evaluated by a number of procedures. The likely site of interaction was shown to be the thiouridine residue (s4U8) based on changes induced by MPT on the absorbance around 330 nm. No changes in stacking interactions could be detected from the absorption or circular dichroic spectra. The detailed structure of the groups on thallium(III) affected the interaction with tRNA. Thalliation at s4U8 affects the absorbance at 335 nm and the amino-acid uptake capacity of E. coli tRNAPhe in parallel, the latter being progressively inhibited by increasing amounts of MPT. In a model nucleoside system, uridine disulphide is probably formed from reduced thiouridine by the oxidative action of the Tl(III) reagents. No evidence of cross-linking of E. coli tRNA molecules under gel electrophoretic conditions was obtained in contrast to the model nucleoside. The easily reversible interaction of MPT with sulphur sites in E. coli tRNA contrasts with the stable (to gel filtration) bonds formed between MPT and (thiol) sites in enzymes.