In vivo pathogenic role of mutant SOD1 localized in the mitochondrial intermembrane space

Mutations in Cu,Zn superoxide dismutase (SOD1) are associated with familial amyotrophic lateral sclerosis (ALS). Mutant SOD1 causes a complex array of pathological events, through toxic gain of function mechanisms, leading to selective motor neuron degeneration. Mitochondrial dysfunction is among the well established toxic effects of mutant SOD1, but its mechanisms are just starting to be elucidated. A portion of mutant SOD1 is localized in mitochondria, where it accumulates mostly on the outer membrane and inside the intermembrane space (IMS). Evidence in cultured cells suggests that mutant SOD1 in the IMS causes mitochondrial dysfunction and compromises cell viability. Therefore, to test its pathogenic role in vivo we generated transgenic mice expressing G93A mutant or wild-type (WT) human SOD1 targeted selectively to the mitochondrial IMS (mito-SOD1). We show that mito-SOD1 is correctly localized in the IMS, where it oligomerizes and acquires enzymatic activity. Mito-G93ASOD1 mice, but not mito-WTSOD1 mice, develop a progressive disease characterized by body weight loss, muscle weakness, brain atrophy, and motor impairment, which is more severe in females. These symptoms are associated with reduced spinal motor neuron counts and impaired mitochondrial bioenergetics, characterized by decreased cytochrome oxidase activity and defective calcium handling. However, there is no evidence of muscle denervation, a cardinal pathological feature of ALS. Together, our findings indicate that mutant SOD1 in the mitochondrial IMS causes mitochondrial dysfunction and neurodegeneration, but per se it is not sufficient to cause a full-fledged ALS phenotype, which requires the participation of mutant SOD1 localized in other cellular compartments.     

Long-term safety and efficacy of rituximab in 248 adults with immune thrombocytopenia: Results at 5 years from the French prospective registry ITP-ritux

Rituximab is a second-line option in adults with immune thrombocytopenia (ITP), but the estimated 5-year response rate, only based on pooled retrospective data, is about 20%, and no studies have focused on long-term safety. We conducted a prospective multicenter registry of 248 adults with ITP treated with rituximab with 5 years of follow-up to assess its long-term safety and efficacy. The median follow-up was 68.4 [53.7-78.5] months. The incidence of severe infections was only 2/100 patient-years. Profound hypogammaglobulinemia (<5 g/L) developed in five patients at 15 to 31 months after the last rituximab infusion. In total, 25 patients died at a median age of 80 [69.5-83.9] years, corresponding to a mortality rate of 2.3/100 patient-years. Only three deaths related to infection that occurred 12 to 14 months after rituximab infusions could be due in part to rituximab. At 60 months of follow-up, 73 (29.4%) patients had a sustained response. On univariate and multivariate analysis, the only factor significantly associated with sustained response was a previous transient response to corticosteroids (P = .022). Overall, 24 patients with an initial response and then relapse received retreatment with rituximab, which gave a response in 92%, with a higher duration of response in 54%. As a result of its safety profile and its sustained response rate, rituximab remains an important option in the current therapeutic armamentarium for adult ITP. Retreatment could be an effective and safe option.     

Postvaccination morphea profunda in a child

We report a new case of postvaccination morphea profunda (MP) in a child and discuss its different clinical presentations, prognosis, and therapy and its relationship with "solitary morphea profunda." A 2-year-old healthy girl presented with an induration of the anterior aspect of the left thigh of 9 months duration. The lesion had appeared 3 months after a third dose of diphtheria-tetanus-pertussis vaccine. Cutaneous examination showed an induration of 7 × 7 cm with an "orange peel" texture after pinching the skin. Histologic examination confirmed the diagnosis of MP. Systemic steroids (1 mg/kg/day) led to the stabilization of the lesion. After 4 months of treatment, we began the concomitant use of oral methotrexate (10 mg/wk) for 2 months. Methotrexate was then continued alone for 10 months, leading to a significant regression of the induration with no relapse.     

Internal translation initiation stimulates expression of the ARF/core+1 open reading frame of HCV genotype 1b

The hepatitis C virus possesses an alternative open reading frame overlapping the Core gene, whose products are referred to as Core+1 or alternative reading frame (ARF) or F protein(s). Extensive studies on genotype HCV-1a demonstrated that ribosomal frameshifting supports the synthesis of core+1 protein, when ten consecutive As are present within core codons 9-11 whereas, in the absence of this motif, expression of the core+1 ORF is mediated mainly by internal translation initiation. However, in HCV-1b, no Core+1 isoforms produced by internal translation initiation have been described. Using constructs which contain the Core/Core+1(342-770) region from previously described HCV-1b clinical isolates from liver biopsies, we provide evidence for the synthesis of Core+1 proteins by internal translation initiation in transiently transfected mammalian cells using nuclear or cytoplasmic expression systems. Site directed mutagenesis analyses revealed that (a) the synthesis of Core+1 proteins is independent from the polyprotein expression, as we observed an increase of Core+1 protein expression from constructs lacking the polyprotein translation initiator, (b) the main Core+1 product is expressed from AUG(85), similarly to the Core+1/S protein of HCV-1a, (c) synthesis of Core+1 isoforms is also mediated from GUG(58) or under certain conditions GUG(26) internal codons, albeit at lower efficiency. Finally, comparable to HCV-1a Core+1 proteins, the HCV-1b Core+1 products are negatively regulated by core expression and the proteaosomal pathway. The expression of Core+1 ORF from HCV-1b clinical isolates and the preservation of translation initiation mechanism that stimulates its expression encourage investigating the role of these proteins in HCV pathogenesis.     

In vivo binding of the dopamine-1 receptor PET tracers [11C]NNC112 and [11C]SCH23390: a comparison study in individuals with schizophrenia

Rationale

A deficit in dopamine-1 (D₁) receptor function in the prefrontal cortex is suggested to play a role in the cognitive dysfunction observed in patients with schizophrenia. However, the results from positron emission tomography imaging studies of D₁ receptor levels in individuals with schizophrenia are mixed.

Objectives

The aim of this investigation was to determine whether the in vivo characteristics of the different D₁ receptor tracers used in previous reports, [¹¹C]SCH23390 and [¹¹C]NNC112, may have contributed to these discrepancies reported in the literature.

Methods

Eight patients with schizophrenia and 12 healthy control subjects were scanned with both [¹¹C]SCH23390 and [¹¹C]NNC112.

Results

[¹¹C]SCH23390 and [¹¹C]NNC112 binding potentials in both patients and control subjects were compared and no tracer by diagnosis interactions were observed.

Conclusions

The results of this study suggest that differences in the binding of [¹¹C]SCH23390 and [¹¹C]NNC112 observed in previous studies are not due to differences in the in vivo behavior of these tracers.     

Severe and prolonged lymphopenia observed in patients treated with bendamustine and erlotinib for metastatic triple negative breast cancer

Purpose

Triple negative breast cancers (TNBC) frequently have high epidermal growth factor receptor (EGFR) expression and are sensitive to DNA-damaging agents. Improved therapies are needed for this aggressive malignancy.

Patients and methods

We performed a phase I trial of bendamustine and erlotinib, an EGFR tyrosine kinase inhibitor, in patients with metastatic TNBC, ECOG performance status ≤2, and ≤1 prior chemotherapy for metastatic disease. Each 28-day cycle included intravenous bendamustine on days 1, 2 and oral erlotinib on days 5–21 with dose escalation according to a 3 + 3 phase I study design. Dose-limiting toxicity (DLT) was determined by toxicities related to study therapy observed during cycle 1.

Results

Eleven patients were treated, 5 on dose level 1 and 6 on dose level 2. One patient had DLT on dose level 2. However, cumulative toxicities were observed, including grade 3/4 lymphopenia in 91 % (95 % CI 0.59–0.998) with progressively decreased CD4 counts and grade ≥3 infections in 36 % (95 % CI 0.11–0.69) of patients.

Conclusions

Combination therapy with bendamustine and erlotinib causes excessive toxicity with severe, prolonged lymphopenia, depressed CD4 counts, and opportunistic infections and should not be pursued further. Future trials of bendamustine combinations in TNBC patients should account for potential cumulative lymphocyte toxicity necessitating patient monitoring during and after treatment.