Osteoclast-poor human osteopetrosis due to mutations in the gene encoding RANKL.

Autosomal recessive osteopetrosis is usually associated with normal or elevated numbers of nonfunctional osteoclasts. Here we report mutations in the gene encoding RANKL (receptor activator of nuclear factor-KB ligand) in six individuals with autosomal recessive osteopetrosis whose bone biopsy specimens lacked osteoclasts. These individuals did not show any obvious defects in immunological parameters and could not be cured by hematopoietic stem cell transplantation; however, exogenous RANKL induced formation of functional osteoclasts from their monocytes, suggesting that they could, theoretically, benefit from exogenous RANKL administration.

A prospective survey on incidence, risk factors and therapy of hepatic veno-occlusive disease in children after hematopoietic stem cell transplantation.

BACKGROUND AND OBJECTIVES: Veno-occlusive disease (VOD) is one of the most frequent complications after stem cell transplantation. We conducted a prospective survey of 244 hematopoietic stem cell transplants in children to determine the incidence of VOD, its main risk factors, treatment and effect on the transplant. DESIGN AND METHODS: Two hundred and forty-four hematopoietic stem cell transplants (HSCT) performed in 220 pediatric patients from 1993 to 2003 were evaluated. The series included 127 males and 93 females with a median age of 6.7 years at the time of transplantation. RESULTS: VOD was diagnosed following 26 of the 244 transplants (cumulative incidence 11%), but a higher incidence was found in patients with at least one known risk factor for VOD (cumulative incidence 20%). In multivariate analysis, risk factors for VOD were age < 6.7 years; type of VOD prophylaxis, and busulphan-containing conditioning regimens. Routine treatment of VOD was based on supportive care and, starting from 1999, defibrotide was used. All patients were monitored with daily Doppler ultrasound-(US) for early diagnosis of inversion of portal blood flow. Twelve patients developed inversion of portal flow (9 had severe VOD; 3 had moderate VOD) and were promptly started on fibrinolytic and anticoagulant therapy with heparin and recombinant tissue plasminogen activator (rt-PA). Hepatic flow reverted to normal in all 12 patients; only 4 patients ultimately developed multiorgan failure and died. The transplant-related-mortality (TRM) rate in patients with or without inversion of portal flow was 33% vs 7%, (p=0.1). The TRM in patients with or without VOD was 19% vs 8% (p=0.001). INTERPRETATION AND CONCLUSIONS: This study showed that younger age, type of VOD prophylaxis, and busulphan-based conditioning regimens are independent risk factors for VOD. Inversion of portal flow was found in 9 of 10 patients with severe VOD. Doppler US monitoring may be helpful in early identification of the patients with VOD-induced inversion of portal flow who might benefit from therapy with heparin and rt-PA.

Prolonged thromboprophylaxis with oral anticoagulants after total hip arthroplasty: a prospective controlled randomized study.

BACKGROUND: The optimal duration of thromboprophylaxis after major orthopedic surgery is controversial. Although oral anticoagulants are still widely used for the prevention of venous thromboembolism after hip replacement, to our knowledge no study has assessed the benefit of prolonging anticoagulation beyond the hospital stay. METHODS: Consecutive patients who had received warfarin sodium prophylaxis after total hip arthroplasty were randomized to stop taking the drug at the time of hospital discharge or to continue taking it for 4 more weeks. The rate of symptomatic and asymptomatic venous thromboembolic events (as shown by compression ultrasonography of the proximal-vein system) occurring during the study period was compared between the 2 groups. The study was prematurely terminated after the inclusion of the first 360 patients because a statistically significant and clinically relevant superiority of extended over short-term thromboprophylaxis was observed. RESULTS: Objectively confirmed venous thromboembolic complications were recorded in 10 patients: 9 (5.1%) in the group of 176 control patients, and 1 (0.5%) in the group of 184 patients who continued the warfarin treatment. The absolute difference in the incidence of events was 4.57% (95% confidence interval [CI], 1.15-7.99). The relative risk of venous thromboembolism developing in control patients compared with patients assigned to extended thromboprophylaxis was 9.4 (95% CI, 1.2-73.5). The number needed to treat was 22. Major bleeding developed in 1 patient who was randomized to the extended prophylaxis group (0.5%; 95% CI, 0.02-3.0) compared with none in the control group. CONCLUSION: Extending prophylaxis with warfarin for a few more weeks beyond the hospital stay has the potential to considerably improve the outcome of patients who undergo hip arthroplasty.

The role of Helicobacter pylori in children with chronic idiopathic thrombocytopenic purpura.

Recent reports have suggested that Helicobacter pylori infection may be a causative agent of adult chronic idiopathic thrombocytopenic purpura (cITP) and antimicrobial treatment may increase platelet counts. As there is limited experience in pediatric age, we investigated the prevalence of H. pylori infection and the effects of H. pylori eradication therapy in a series of children with cITP. Twenty-four children with cITP were investigated for H. pylori infection using the C-urea breath test or H. pylori fecal antigen. In cases of H. pylori infection, antimicrobial treatment was given with amoxicillin, clarithromycin, and proton pump inhibitors. Response was assessed at 6 months and defined as complete (platelet count >150x10/L) or partial (platelet count between 50 and 150x10/L). H. pylori infection was found in 8 patients (33%) and 3 of them showed a response after eradication therapy, but 2 of them relapsed later on. Two patients had a spontaneous increase in platelet count in the group of H. pylori-negative patients. Given that spontaneous improvements in platelet count can occur in children with cITP, we were unable to demonstrate that H. pylori plays a major role in cITP occurring in pediatric age.