Molecular characterization of commercial porcine factor VIII concentrate

Commercial porcine factor VIII concentrate (Hyate:C) is effective in treatment of patients with hemophilia A who have circulating antibodies to factor VIII. The molecular forms of factor VIII in the concentrate were identified and evaluated in light of the known properties of porcine and human factor VIII. The factor VIII in the concentrate was isolated by tandem chromatography on gelatin-Sepharose and monoclonal anti-factor VIII-Sepharose. The factor VIII was 1% of the protein mass of the concentrate when calculated by either quantity of protein recovered or by radioimmunoassay. Both functional assay and Western blotting of the crude concentrate indicated that maximum coagulant function was achieved by proteolytic activation of procofactor forms of factor VIII. The factor VIII can be fractionated by cation-exchange high-performance liquid chromatography (HPLC) into two or three species of heterodimers depending on the lot. The specific activity of the purified porcine factor VIII was 550 U/mg using pooled porcine plasma at 1 U/mL as a standard. From this value, a factor VIII concentration in normal pig plasma of 2 micrograms/mL was calculated. This agreed well with a value of 3 micrograms/mL obtained by radioimmunoassay (RIA) of factor VIII in porcine plasma. In contrast, reported values for human factor VIII average 5800 U/mg, resulting in a calculated concentration in plasma of 0.2 microgram/mL. The finding that porcine plasma contains a significantly higher circulating mass of factor VIII than human plasma appears to explain previous difficulties in comparing porcine and human factor VIII in standard assays.     

Cloning of glycoprotein IIIa cDNA from human erythroleukemia cells and localization of the gene to chromosome 17

Platelet aggregation requires the binding of adhesive proteins such as fibrinogen to the heterodimer of membrane glycoproteins IIb (GPIIb) and IIIa (GPIIIa). Human erythroleukemia (HEL) cells synthesize both GPIIb and GPIIIa. Using poly(A+) RNA purified from HEL cells, we constructed a cDNA library in the lambda gt10 phage vector. This library was screened with a 38mer oligonucleotide derived from a platelet GPIIIa peptide, and three overlapping cDNAs were isolated. The three inserts encompassed 3.5 kilobases (kb), including the entire coding region of mature GPIIIa (2,286 basepairs, bp) and 1.3 kb of 3' untranslated sequence. All 222 residues determined directly from platelet GPIIIa tryptic peptides exactly matched the HEL cell-deduced amino acid sequence. The HEL cell sequence matched a previously reported endothelial cell cDNA sequence except for eight nucleotides. Five of these nucleotide differences were silent changes consistent with genetic polymorphisms. The other three differences resulted in changes in the deduced amino acid sequence of GPIIIa; reexamination of the endothelial cell cDNA sequence in these three areas revealed that it is actually identical to the HEL cell sequence. The virtual identity of the endothelial and HEL cell cDNA sequences provides direct evidence that GPIIIa is a subunit common to cell-adhesion receptors present in more than one cell type. We localized the gene for GPIIIa to chromosome 17, the same chromosome to which we had previously mapped the gene for GPIIb.     

Nonheme iron in sickle erythrocyte membranes: association with phospholipids and potential role in lipid peroxidation

Previous studies documented the abnormal association of heme and heme proteins with the sickle RBC membrane. We have now examined RBC ghosts and inside-out membranes (IOM) for the presence of nonheme iron as detected by its formation of a colored complex with ferrozine. Sickle ghosts have 33.8 +/- 18.2 nmol nonheme iron/mg membrane protein, and sickle IOM have 4.3 +/- 3.0 nmol/mg. In contrast, normal RBC ghosts and IOM have no detectable nonheme iron. The combination of heme and nonheme iron in sickle IOM averages nine times the amount of membrane- associated iron in normal IOM. Kinetics of the ferrozine reaction show that some of this nonheme iron on IOM reacts slowly and is probably in the form of ferritin, but most (72% +/- 18%) reacts rapidly and is in the form of some other biologic chelate. The latter iron compartment is removed by deferoxamine and by treatment of IOM with phospholipase D, which suggests that it represents an abnormal association of iron with polar head groups of aminophospholipids. The biologic feasibility of such a chelate was demonstrated by using an admixture of iron with model liposomes. Even in the presence of tenfold excess adenosine diphosphate, iron partitions readily into phosphatidylserine liposomes; there is no detectable association with phosphatidylcholine liposomes. To examine the bioavailability of membrane iron, we admixed membranes and t-butylhydroperoxide and found that sickle membranes show a tenfold greater peroxidation response than do normal membranes. This is not due simply to a deficiency of vitamin E, and this is profoundly inhibited by deferoxamine. Thus, while thiol oxidation in sickle membranes previously was shown to correlate with heme iron, the present data suggest that lipid peroxidation is related to nonheme iron. In control studies, we did not find this pathologic association of nonferritin, nonheme iron with IOM prepared from sickle trait, high-reticulocyte, postsplenectomy, or iron-overloaded individuals. These data provide additional support for the concept that iron decompartmentalization is a characteristic of sickle RBCs.     

Impact of residential medication management reviews on anticholinergic burden in aged care residents

Objectives:

The primary objective of this study was to investigate the impact of Residential Medication Management Reviews (RMMRs) on anticholinergic burden quantified by seven anticholinergic risk scales.

Design:

Retrospective analysis.

Setting:

Accredited pharmacists conducted RMMRs in aged-care facilities (ACFs) in Sydney, Australia.

Participants:

RMMRs pertained to 814 residents aged 65 years or older.

Measurements:

Anticholinergic burden was quantified using seven scales at baseline, after pharmacists’ recommendations and after the actual GP uptake of pharmacists’ recommendations. Change in the anticholinergic burden was measured using the Wilcoxon sign rank test.

Results:

At baseline, depending on the scale used to estimate the anticholinergic burden, between 36% and 67% of patients were prescribed at least one regular anticholinergic medication (ACM). Anticholinergic burden scores were significantly (p?<?0.001) lower after pharmacists’ recommendations as determined by each of the seven scales. The reduction in anticholinergic burden was also significant (p?<?0.001) after GPs’ acceptance of the pharmacists’ recommendations according to all scales with the exception of one scale which reached borderline significance (p?=?0.052).

Conclusion:

Despite the limitations of the retrospective design and differences in the estimation of anticholinergic burden, this is the first study to demonstrate that RMMRs are effective in reducing ACM prescribing in ACF residents, using a range of measures of anticholinergic burden. Future studies should focus on whether a decrease in anticholinergic burden will translate into improvement in clinical outcomes.     

T1‐weighted fluid‐attenuated inversion recovery and T1‐weighted fast spin‐echo contrast‐enhanced imaging: A comparison in 20 patients with brain lesions

T1‐weighted fluid‐attenuated inversion recovery (FLAIR) sequence is a relatively new pulse sequence for intracranial MR imaging. This study was performed to compare the image quality of T1‐weighted FLAIR with the T1‐weighted FSE sequence. Twenty patients with brain lesions underwent T1‐weighted fast spin‐echo (FSE) and T1‐weighted FLAIR during the same imaging session. Four quantitative and three qualitative criteria were used to compare the two sequences after contrast. Two of four quantitative criteria pertained to lesion characteristics: lesion to white matter (WM) contrast‐to‐noise ratio (CNR) and lesion to cerebrospinal fluid (CSF) CNR, and two related to signals from normal tissue: grey matter to WM CNR and WM to CSF CNR. The three qualitative criteria were conspicuousness of the lesion, the presence of image artefacts and the overall image contrast. Both T1‐weighted FSE and FLAIR images were effective in demonstrating lesions. Image contrast was superior in T1‐weighted FLAIR images with significantly improved grey matter‐WM CNRs and CSF‐WM CNRs. The overall image contrast was judged to be superior on T1‐weighted FLAIR images compared with T1‐weighted FSE images by all neuroradiologists. Two of three reviewers considered that the FLAIR images had slightly increased imaging artefacts that, however, did not interfere with image interpretation. T1‐weighted FLAIR imaging provides improved lesion‐to‐background and grey to WM contrast‐to‐noise ratios. Superior conspicuity of lesions and overall image contrast is obtained in comparable acquisition times. These indicate an important role for T1‐weighted FLAIR in intracranial imaging and highlight its advantage over the more widely practiced T1‐weighted FSE sequence.     

Refrigerated storage of lyophilized and rehydrated, lyophilized human red cells

Human red cells (RBCs) were collected in CPDA-1 and then freeze-dried in lyoprotective solution. The lyophilized RBCs were then stored at -20 degrees C for 7 days. At the end of the storage period, the lyophilized RBCs were rehydrated and washed in dextrose saline. The washed, reconstituted, lyophilized RBCs were resuspended in final wash solutions of ADSOL, CPDA-1, or a special additive solution containing glucose, citrate, phosphate, adenine, and mannitol, and then they were stored at 4 degrees C for an additional 7 days. The main purpose of this study was to determine whether human RBCs can be lyophilized in such a manner that normal metabolic, rheologic, and cellular properties are maintained during rehydration and subsequent storage in standard blood bank preservative solutions. Our results show that reconstituted, lyophilized RBCs maintained levels of ATP, 2,3 DPG, lactate, and cellular properties that are equal to or better than those in control nonlyophilized RBCs stored for a comparable period in CPDA-1. Reconstituted, lyophilized RBCs stored at 4 degrees C after rehydration also show better maintenance of ATP, 2,3 DPG, and lactate than do control RBCs stored in the same preservative solutions for comparable periods.     

Minor head trauma-induced sporadic hemiplegic migraine coma

Familial hemiplegic migraine is a severe, rare subtype of migraine. Gene mutations on chromosome 19 have been identified in the calcium channel, voltage-dependent, P/Q type, alpha-1A subunit gene (chromosome 19p13) for familial hemiplegic migraine. Recently a gene mutation (Serine-218-Leucine) for a dramatic syndrome associated with familial hemiplegic migraine, commonly named "migraine coma", has implicated exon 5 of this gene. The occurrence of trivial head trauma, in such familial hemiplegic migraine patients, may also be complicated by severe, sometimes even fatal, cerebral edema and coma occurring after a lucid interval. Sporadic hemiplegic migraine shares a similar spectrum of clinical presentation and genetic heterogeneity. The case report presented in this article implicates the involvement of the Serine-218-Leucine mutation in the extremely rare disorder of minor head trauma-induced migraine coma. We conclude that the Serine-218-Leucine mutation in the calcium channel, voltage-dependent, P/Q type, alpha-1A subunit gene is involved in sporadic hemiplegic migraine, delayed cerebral edema and coma after minor head trauma.     

Genetic investigation of methylenetetrahydrofolate reductase (MTHFR) and catechol-O-methyl transferase (COMT) in multiple sclerosis

Multiple sclerosis (MS) is a chronic neurological disease characterized by central nervous system (CNS) inflammation and demyelination. The C677T substitution variant in the methylenetetrahydrofolate reductase (MTHFR) gene has been associated with increased levels of circulating homocysteine and is a mild risk factor for vascular disease. Higher blood levels of homocysteine have also been reported in MS. Thus, the C677T mutation of the MTHFR gene may influence MS susceptibility. Noradrenaline, a neurotransmitter believed to play an immunosupressive role in neuroinflammatory disorders, is catabolized by catechol-O-methyl transferase (COMT). The COMT G158A substitution results in a three- to four-fold decreased activity of the COMT enzyme, which may influence CNS synaptic catecholamine breakdown and could also play a role in MS inflammation. We tested DNA from Australian MS patients and unaffected control subjects, matched for gender, age and ethnicity. Specifically, we genotyped the MTHFR C677T and the COMT G158A mutations. Genotype distributions showed that the homozygous mutant MTHFR genotype (T/T) and the COMT (H/H) genotype were slightly over-represented in the MS group (16% versus 11% and 24% versus 19%, respectively), but both variations failed to reach statistical significance (P=0.15 and P=0.32, respectively). Hence, results from the present study do not support a major role for either functional gene mutation in MS susceptibility.