Mature B-NHL in children, adolescents and young adults: current therapeutic approach and emerging treatment strategies.

Mature B cell lymphomas account for approximately 60% of all cases of non-Hodgkin lymphoma (NHL) in children and adolescents and includes Burkitt lymphoma (BL), diffuse large B cell lymphoma (DLBCL) and other less common histologies. The outcome for patients treated with modern regimens in resource-intensive settings is excellent. Improvements in care have been accomplished through enhanced supportive therapy, including tumour lysis management and incremental refinement of chemotherapy backbones via cooperative group clinical trials in which patients receive risk group-specific intensive chemotherapy. More recent trials have established the safety and efficacy of immunotherapy. Ongoing work is required to address the substantial burden of acute therapy-related toxicity, as well as the identification of effective therapies for those patients with relapsed and refractory disease, for whom outcomes remain very poor. In this review we will summarize the results from recent therapeutic clinical trials, describe the evidence to support the inclusion of rituximab and review the rationale for the investigation of several new categories of novel agents for mature B cell lymphomas in children and adolescents.

The twin arginine translocation system is essential for aerobic growth and full virulence of Burkholderia thailandensis.

The twin arginine translocation (Tat) system in bacteria is responsible for transporting folded proteins across the cytoplasmic membrane, and in some bacteria, Tat-exported substrates have been linked to virulence. We report here that the Tat machinery is present in Burkholderia pseudomallei, B. mallei, and B. thailandensis, and we show that the system is essential for aerobic but not anaerobic growth. Switching off of the Tat system in B. thailandensis grown anaerobically resulted in filamentous bacteria, and bacteria showed increased sensitivity to some ß-lactam antibiotics. In Galleria mellonella and zebrafish infection models, the Tat conditional mutant was attenuated. The aerobic growth-restricted phenotype indicates that Tat substrates may play a functional role in oxygen-dependent energy conservation. In other bacteria, aerobic growth restriction in Tat mutants has been attributed to the inability to translocate PetA, the Rieske iron-sulfur protein which forms part of the quinol-cytochrome c oxidoreductase complex. Here, we show that PetA is not responsible for aerobic growth restriction in B. thailandensis. However, we have identified an operon encoding 2 proteins of unknown function (BTH_I2176 and BTH_I2175) that play a role in aerobic growth restriction, and we present evidence that BTH_I2176 is Tat translocated.

Superoxide dismutase C is required for intracellular survival and virulence of Burkholderia pseudomallei.

Burkholderia pseudomallei is an intracellular pathogen and the causative agent of melioidosis, a life-threatening disease of humans. Within host cells, superoxide is an important mediator of pathogen killing. In this study, we have identified the B. pseudomallei K96243 sodC gene, shown that it has superoxide dismutase activity, and constructed an allelic deletion mutant of this gene. Compared with the wild-type, the mutant was more sensitive to killing by extracellular superoxide, but not to superoxide generated intracellularly. The sodC mutant showed a markedly decreased survival in J774A.1 mouse macrophages, and reduced numbers of bacteria were recovered from human polymorphonuclear neutrophils (PMNs) when compared with the wild-type. The numbers of wild-type or mutant bacteria recovered from human diabetic neutrophils were significantly lower than from normal human neutrophils. The sodC mutant was attenuated in BALB/c mice. Our results indicate that SodC plays a key role in the virulence of B. pseudomallei, but that diabetics are not more susceptible to infection because of a reduced ability of PMNs to kill by superoxide.

Neurodegenerative central nervous system Langerhans cell histiocytosis and coincident hydrocephalus treated with vincristine/cytosine arabinoside.

BACKGROUND: Central nervous system (CNS) complications of Langerhans cell histiocytosis (LCH) include mass lesions and a neurodegenerative (ND) syndrome with ataxia, dysarthria, dysmetria, learning and behavior difficulties and/or characteristic changes on brain MRIs. Hydrocephalus has rarely been reported in LCH. LCH lesions of the orbit, mastoid and temporal bones ("CNS-Risk" lesions) and diabetes insipidus predispose patients to ND-CNS-LCH. Treatment options have been limited and only a case series using trans-retinoic acid (ATRA) and intravenous immunoglobulin (IVIG) have been published. METHODS: We have used cytosine arabinoside (ARA-C) with or without vincristine to treat eight patients with ND-CNS LCH. PATIENTS: Seven male children and one young adult male with clinical and radiologic ND-CNS-LCH were treated with a regimen of vincristine 1.5 mg/m(2) on day 1 and ARA-C 100 mg/m(2) daily for 5 days or ARA-C alone monthly for 4-19 months. Seven patients were evaluated with an ataxia rating scale (ARS) and all with serial MRIs of the brain. RESULTS: Five of seven patients had decreases in their ARS scores and/or decreased T2 hyperintense lesions on MRI images. Grade 2 neutropenia was the most frequent adverse event. Vincristine-associated neuropathy occurred in two patients. Hydrocephalus caused symptoms and signs that confounded the diagnosis and management of ND-CNS-LCH in all four patients affected with both. CONCLUSIONS: Subtle changes in neurologic function may be complicated by hydrocephalus. Vcr/ARA-C or ARA-C were an effective therapies for some ND-CNS LCH patients. A clinical trial using this and possibly other modalities such as IVIG or ATRA should be done.

Galleria mellonella as a model system to test the pharmacokinetics and efficacy of antibiotics against Burkholderia pseudomallei.

Mammalian models of infection are paramount to elucidating the mechanisms of bacterial pathogenesis and are also used for evaluating the efficacy of novel antimicrobials before the commencement of human trials. In this study, Galleria mellonella was used to determine the efficacy of antibiotics towards a Burkholderia thailandensis infection in G. mellonella larvae. Kanamycin, imipenem, ceftazidime, doxycycline and ciprofloxacin could all provide some protection when given 1 h before challenge with B. thailandensis; however, at 2 h or 6 h post challenge, imipenem and kanamycin were unable to rescue larvae. The most effective antibiotic for the prevention or treatment of disease was ceftazidime. Pharmacokinetic properties of a single dose of these antibiotics in G. mellonella larvae were also determined, and it was demonstrated that this model is useful for approximating the antibiotic response in humans. The G. mellonella model was used to screen a panel of novel antimicrobials for activity towards B. thailandensis and Burkholderia pseudomallei, and three novel compounds with antibiotic activity were identified. These results support the hypothesis that G. mellonella can be used to screen antimicrobial efficacy. This is the first study to determine the pharmacokinetic parameters of clinically relevant antibiotics in this model system.

Failure to treat obstructive hydrocephalus with endoscopic third ventriculostomy in a patient with neurodegenerative Langerhans cell histiocytosis.

The second most frequent central nervous system involvement pattern in Langerhans cell histiocytosis (LCH) is a rare condition documented in a number of reports called "neurodegenerative LCH" (ND-LCH). Magnetic resonance images confirming the presence of the disease usually demonstrate striking symmetric bilateral hyperintensities predominantly in the cerebellum, basal ganglia, pons, and/or cerebral white matter. The authors here describe for the first time in the literature a patient with ND-LCH and concomitant hydrocephalus initially treated using endoscopic third ventriculostomy (ETV). This 9-year-old boy, who had undergone chemotherapy for skin and lung LCH without central nervous system involvement at the age of 10 months, presented with acute ataxia, headaches, and paraparesis and a 1-year history of gradually increasing clumsiness. Magnetic resonance images showed obstructive hydrocephalus at the level of the aqueduct of Sylvius and signs of ND-LCH. After registering high intracranial pressure (ICP) spikes with an intraparenchymal pressure monitor, an ETV was performed. A second ETV was required months later because of ostomy occlusion, and finally a ventriculoperitoneal shunt was placed because of ostomy reocclusion. Endoscopic third ventriculostomy was initially considered the treatment of choice to divert cerebrospinal fluid without leaving a ventriculoperitoneal shunt and to obtain biopsy specimens from the periinfundibular recess area. The third ventriculostomy occluded twice, and an endoscopic aqueduct fenestration was unsuccessful. The authors hypothesized that an inflammatory process related to late ND disease was responsible for the occlusions. Biopsy specimens from the infundibular recess and fornix column did not show histopathogical abnormalities. Increased ICP symptoms resolved with cerebrospinal fluid diversion. This case is the first instance of ND-LCH with hydrocephalus reported in the literature to date. Shunt placement rather than ETV seems to be the favorable choice in relieving elevated ICP.