Homozygous cystathionine beta-synthase deficiency, combined with factor V Leiden or thermolabile methylenetetrahydrofolate reductase in the risk of venous thrombosis

Severe hyperhomocysteinemia in its most frequent form, is caused by a homozygous enzymatic deficiency of cystathionine beta-synthase (CBS). A major complication in CBS deficiency is deep venous thrombosis or pulmonary embolism. A recent report by Mandel et al (N Engl J Med 334:763, 1996) postulated factor V Leiden (FVL) to be an absolute prerequisite for the development of thromboembolism in patients with severe hyperhomocysteinemia. We studied 24 patients with homocystinuria caused by homozygous CBS deficiency from 18 unrelated kindreds for FVL and for the 677C-->T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene and investigated their possible interaction in the risk of venous thrombosis. Thrombotic complications were diagnosed in six patients, of whom only one was a carrier of FVL. On the contrary, thermolabile MTHFR caused by the 677C-->T mutation, was frequently observed among homocystinuria patients, especially among those with thromboembolic complications: three of six homocystinuria patients who had suffered from a thromboembolic event had thermolabile MTHFR. These data indicate that FVL is not an absolute prerequisite and probably not even a major determinant of venous thrombosis in homocystinuria, but, interestingly, thermolabile MTHFR may constitute a significant risk factor for thromboembolic complications in this inborn error of methionine metabolism.     

The activity of the high-affinity K+ uptake system Kdp sensitizes cells of Escherichia coli to methylglyoxal

Expression of the Kdp system sensitizes cells to methylglyoxal (MG) whether this electrophile is added externally or is synthesized endogenously. The basis of this enhanced sensitivity is the maintenance of a higher cytoplasmic pH (pHi) in cells expressing Kdp. In such cells, MG elicits rapid cytoplasmic acidification via KefB and KefC, but the steady-state pHi attained is still too high to confer protection Lowering pHi further by incubation with acetate increases the sensitivity of cells to MG.     

Causes of death in Canadians with haemophilia 1980-1995. Association of Hemophilia Clinic Directors of Canada

The life expectancy of individuals with haemophilia was close to that of the general population in the early 1980s. Since then, life expectancy has decreased, due to transfusion-transmitted virus infections. Deaths in individuals with haemophilia were investigated by analysing 2450 records from the Canadian Hemophilia Registry, for the years 1980-1995. Deaths were tabulated by age, year and cause, and compared with that of the Canadian male population by calculating standardized mortality ratios (SMRs). The median life expectancy at 1 year of age was calculated for various subpopulations and the impact of various population characteristics was assessed by survival regression modelling. There were 359 deaths and the annual number of deaths increased significantly after 1986. Risk factors were seropositivity to human immunodeficiency virus (relative risk 16.7, 95% CI 11.1-25.1), severe haemophilia (1.9, 1.3-2.7) and moderate haemophilia (1.8, 1.2-2.6). In HIV antibody negative individuals, the overall death rate was not increased (SMR 0.9, 95% CI 0.7-1.1) and only haemorrhage was significantly increased. In HIV antibody positive individuals, causes of death which were significantly increased were acquired immunodeficiency syndrome, liver failure, haemorrhage, lymphoma, liver cancer, nonspecific infections, and trauma or violence. Deaths due to the acquired immunodeficiency syndrome accounted for only 66% of the excess deaths in individuals who were HIV antibody positive. Life expectancy has markedly decreased since the onset of the HIV epidemic. The impact of HIV is underestimated by considering only deaths due to the acquired immunodeficiency syndrome; other HIV-linked causes need also to be considered.     

'Rescue' after failed thrombolysis for acute myocardial infarction

Prompt restoration of coronary artery patency in acute myocardial infarction is associated with substantial improvements in morbidity and mortality. The pivotal role of thrombolysis and aspirin in achieving these goals is well established. However, despite the success of thrombolytic therapy in large trials, clinical assessment in individual patients often suggests that reperfusion has not occurred after initial therapy. This review considers the validity of such bedside predictions and discusses whether such patients should be managed differently.     

Imaging of abdominal manifestations of melanoma

Despite an increasing incidence of melanoma in this country, innovative new therapies are allowing patients to receive aggressive experimental treatments. Diagnostic imaging remains crucial for tumor staging and for follow-up of patients being treated with these protocols. Because metastases occur in the abdomen and pelvis in approximately 60% of patients, it is important to accurately identify all sites of tumor spread. A variety of imaging techniques are used to image these patients, with CT currently being used for staging purposes and to guide diagnostic biopsies. Other imaging techniques, such as MR, ultrasound, and fluoroscopy, are currently reserved for investigating specific complications of melanoma, such as vascular invasion, hemorrhage from a tumor, and small bowel involvement, including intussusception. Recently, whole body positron emission tomography (PET) imaging using 2-deoxy-2-fluoro-D-glucose (FDG) has been shown to be highly accurate in assessing patients with metastatic malignant melanoma. This review illustrates the spectrum of manifestations of metastatic melanoma throughout the abdomen and pelvis, including solid organ, hollow lumen, and retroperitoneal involvement, and demonstrates some of the typical and atypical manifestations that may be identified.     

Human herpesvirus-6 infection in liver transplant recipients: documentation of pathogenicity

In the posterior partially edentulous jaw, implants may be used to supplement existing natural dentition. Frequently, the maxillary sinuses and the mandibular nerve preclude the fabrication of freestanding implant-retained prostheses. However, if an implant and a natural abutment are combined, a fixed prosthesis can be fabricated, restoring the arch into the premolar area. The histories of three patients with attachments connecting implant-retained ceramotitanium crowns with crowns on natural abutments are described. A design for a rigid custom-made attachment for the Br?nemark system, using standard components with a machine-duplication, spark-erosion technique, is suggested.