The incidence of heparin-induced thrombocytopenia in hospitalized medical patients treated with subcutaneous unfractionated heparin: a prospective cohort study

Although heparin-induced thrombocytopenia (HIT) is a known complication of intravenous unfractionated heparin (UFH), its incidence in medical patients treated with subcutaneous UFH is less well defined. To determine the incidence of HIT in this category of patients, the platelet count was performed at baseline and then every 3 +/- 1 days in 598 consecutive patients admitted to 2 medical wards and treated with subcutaneous UFH for prophylactic (n = 360) or therapeutic (n = 238) indications. The diagnosis of HIT was accepted in the case of a platelet drop of 50% or more and either the demonstration of heparin-dependent antibodies or (when this search could not be performed) the combination of the following features: (1) the absence of any other obvious clinical explanation for thrombocytopenia, (2) the occurrence of thrombocytopenia at least 5 days after heparin start, and (3) either the normalization of the platelet count within 10 days after heparin discontinuation or the earlier patient's death due to an unexpected thromboembolic complication. HIT developed in 5 patients (0.8%; 95% CI, 0.1%-1.6%); all of them belonged to the subgroup of patients who received heparin for prophylactic indications. The prevalence of thromboembolic complications in patients with HIT (60%) was remarkably higher than that observed in the remaining 593 patients (3.5%), leading to an odds ratio of 40.8 (95% CI, 5.2-162.8). Although the frequency of HIT in hospitalized medical patients treated with subcutaneous heparin is lower than that observed in other clinical settings, this complication is associated with a similarly high rate of thromboembolic events.     

Alterations in myocardial tissue factor expression and cellular localization in dilated cardiomyopathy

OBJECTIVES: We investigated the myocardial localization and expression of tissue factor (TF) and alternatively spliced human tissue factor (asHTF) in patients with dilated cardiomyopathy (DCM). BACKGROUND: Tissue factor is expressed in cardiac muscle and may play a role in maintaining myocardial structure. METHODS: Myocardial biopsies were obtained from patients with a normal or mildly impaired ejection fraction (EF) (> or =50%) and moderate to severely reduced EF (<50%). Explanted DCM hearts were also examined. Myocardial TF expression level was assessed by real-time polymerase chain reaction, TF protein by enzyme-linked immunosorbent assay, and localization by immunohistochemistry. RESULTS: We report the identification of asHTF in the human myocardium: it was located in cardiomyocytes and endothelial cells. Quantification of myocardial TF messenger ribonucleic acid in DCM revealed a decrease in the TF/glyceraldehyde-3-phosphate dehydrogenase (GAPDH) ratio (1.76 x 10(-1) +/- 6.08 x 10(-2) for EF > or =50% [n = 19] vs. 1.06 x 10(-1) +/- 5.26 x 10(-2) for EF <50% [n = 27]; p < 0.001) and asHTF/GAPDH ratio (13.91 x 10(-5) +/- 11.20 x 10(-5) for EF > or =50% vs. 7.17 x 10(-5) +/- 3.82 x 10(-5) for EF <50%; p = 0.014). Tissue factor isoform expression level was also decreased in explanted DCM hearts (p < 0.01; n = 12). Total TF protein was reduced by 26% in DCM (p < 0.05). The TF/GAPDH ratio correlated positively with the EF (r = 0.504, p < 0.0001). Immunohistochemistry showed TF localized to the sarcolemma and Z-bands of the cardiomyocytes in patients with normal EF, whereas TF was found in the cardiomyocytic cytosol around the nucleus in DCM. CONCLUSIONS: Tissue factor was down-regulated in the myocardium of DCM patients. The reduction in TF expression and change in localization may influence cell-to-cell contact stability and contractility, thereby contributing to cardiac dysfunction in DCM.     

Oral and transdermal estrogens both lower plasma total homocysteine in male-to-female transsexuals

Plasma total homocysteine (tHcy) levels are on average lower in women versus men, indicating an estrogenic effect. Oral estrogens (absorbed via the liver) may be hypothesized to have stronger effects on hepatic homocysteine metabolism than transdermal estrogens. We randomly assigned 30 male-to-female transsexuals (20-44 years old) to 4 months' administration of oral ethinyl estradiol (n=15) or transdermal 17beta-estradiol (n=15), both with the antiandrogen cyproterone acetate (CA). Ten other male controls were treated with CA only. At baseline and after 2 and 4 months, plasma tHcy was analyzed in conjunction with plasma folate. Oral ethinyl estradiol and transdermal 17beta-estradiol similarly reduced plasma tHcy (geometric mean 10.6 micromol/l [95% CI 8.2-13.9] to 7.5 [6.5; 8.8], and 11.3 [8.1; 16.4] to 8.4 [6.5; 11.1]; P<0.001 for both), whereas CA had no effects. No effects were found on folate levels. Thus, oral and transdermal estrogens decrease plasma tHcy to a similar degree (by geometric mean -26%), which suggests that a hepatic mechanism is unlikely to play an important role in the decline of tHcy levels.     

Glycoprotein Ib polymorphisms influence platelet plug formation under high shear rates

Platelet polymorphisms (Kozak, VNTR and HPA-2) within glycoprotein (GP)Ib alpha may be associated with an increased risk of arterial thrombosis. However, the functional role of these polymorphisms has not been clarified. Their influence on platelet plug formation under high shear rates was, therefore, examined in 233 healthy individuals. Collagen-adrenaline-induced closure time was shorter in carriers of the C/D versus C/C VNTR allele and in homozygotes with the (-5)T/T versus (-5)C/T Kozak genotype as determined by novel polymerase chain reaction methods. The HPA-2 genotype had no effects, and the density of GPIb alpha molecules was not influenced by GPIb alpha genotypes.     

Mutations in bone morphogenetic protein receptor 1B cause brachydactyly type A2

Brachydactyly (BD) type A2 is an autosomal dominant hand malformation characterized by shortening and lateral deviation of the index fingers and, to a variable degree, shortening and deviation of the first and second toes. We performed linkage analysis in two unrelated German families and mapped a locus for BD type A2 to 4q21-q25. This interval includes the gene bone morphogenetic protein receptor 1B (BMPR1B), a type I transmembrane serinethreonine kinase. In one family, we identified a T599 --> A mutation changing an isoleucine into a lysine residue (I200K) within the glycine/serine (GS) domain of BMPR1B, a region involved in phosphorylation of the receptor. In the other family we identified a C1456 --> T mutation leading to an arginine-to-tryptophan amino acid change (R486W) in a highly conserved region C-terminal of the BMPR1B kinase domain. An in vitro kinase assay showed that the I200K mutation is kinase-deficient, whereas the R486W mutation has normal kinase activity, indicating a different pathogenic mechanism. Functional analyses with a micromass culture system revealed a strong inhibition of chondrogenesis by both mutant receptors. Overexpression of mutant chBmpR1b in vivo in chick embryos by using a retroviral system resulted either in a BD phenotype with shortening and/or missing phalanges similar to the human phenotype or in severe hypoplasia of the entire limb. These findings imply that both mutations identified in human BMPR1B affect cartilage formation in a dominant-negative manner.     

A randomized, prospective trial of ribavirin 400 mg/day versus 800 mg/day in combination with peginterferon alfa-2a in hepatitis C virus genotypes 2 and 3

We compared the efficacy and tolerability of 24 weeks of treatment with ribavirin 800 mg/day (group A) or 400 mg/day (group B) plus peginterferon alfa-2a 180 mug/week in treatment-naive patients infected with hepatitis C virus (HCV) genotype 2 or 3. A total of 97 of 141 patients randomized to group A (68.8%, 95% confidence interval [CI] 60.5%-76.3%) and 90 of 141 patients randomized to group B (63.8; 95% CI 55.3%-71.7%) achieved a sustained virological response, defined as undetectable serum HCV RNA at the end of untreated follow-up (week 48). Among patients infected with genotype 3, the rate of sustained virological response was 67.5% (95% CI 58.4%-75.6%) in group A and 63.9% (95% CI 54.7%-72.4%) in group B, and among patients infected with genotype 2, the rate of sustained virological response was 77.8% (95% CI 54.2%-93.6%) in group A and 55.6% (95% CI 38.4%-83.7%) in group B. Relapse rates in the 2 treatment groups were similar (17% in group A and 20% in group B). The incidence of adverse events, laboratory abnormalities, and dose reductions was similar in the 2 treatment groups. CONCLUSION: The results suggest that when administered for 24 weeks with peginterferon alfa-2a, ribavirin doses of 400 and 800 mg/day produce equivalent outcomes in patients infected with HCV genotype 3.     

Subclinical impairment of brain function in chronic hepatitis C infection

BACKGROUND/AIMS: Central nervous system abnormalities such as fatigue and depression occur more frequently in chronic hepatitis C virus (HCV) infection than in many other causes of chronic liver disease. The finding that fatigue is unrelated to activity of hepatitis or mode of infection could indicate an independent effect of HCV on brain function. This study tested the hypothesis of a subclinical cognitive dysfunction in HCV-infected patients. METHODS: One-hundred untreated HCV-RNA positive biopsy-proven patients were investigated by P300 event-related potentials, a sensitive electrophysiologic test of cognitive processing. Health-related quality of life and fatigue were assessed using the SF-36 questionnaire and the Fatigue Impact Scale, respectively. RESULTS: Cognitive brain function was subclinically impaired in the cohort of HCV-infected patients as indicated by significantly prolonged P300 latencies (P=0.01 for comparison to matched healthy subjects) and reduced P300 amplitudes (P<0.001, respectively). Seventeen of the 100 HCV-infected patients had P300 latencies outside the age-adjusted normal range. Abnormal P300 characteristics were not related to the degree of histologic or biochemical activity of hepatitis, severity of fatigue or mental health impairment. CONCLUSIONS: This study demonstrates that patients with HCV infection showed a slight but significant neurocognitive impairment, possibly indicating a further extrahepatic manifestation of chronic hepatitis C.     

Genomewide production of multipurpose alleles for the functional analysis of the mouse genome

A type of retroviral gene trap vectors has been developed that can induce conditional mutations in most genes expressed in mouse embryonic stem (ES) cells. The vectors rely on directional site-specific recombination systems that can repair and re-induce gene trap mutations when activated in succession. After the gene traps are inserted into the mouse genome, genetic mutations can be produced at a particular time and place in somatic cells. In addition to their conditional features, the vectors create multipurpose alleles amenable to a wide range of post-insertional modifications. Here we have used these directional recombination vectors to assemble the largest library of ES cell lines with conditional mutations in single genes yet assembled, presently totaling 1,000 unique genes. The trapped ES cell lines, which can be ordered from the German Gene Trap Consortium, are freely available to the scientific community.