PINK1-dependent recruitment of Parkin to mitochondria in mitophagy

Phosphatase and tensin homolog (PTEN)-induced putative kinase 1 (PINK1) and PARK2/Parkin mutations cause autosomal recessive forms of Parkinson''s disease. Upon a loss of mitochondrial membrane potential (ΔΨ_m) in human cells, cytosolic Parkin has been reported to be recruited to mitochondria, which is followed by a stimulation of mitochondrial autophagy. Here, we show that the relocation of Parkin to mitochondria induced by a collapse of ΔΨ_m relies on PINK1 expression and that overexpression of WT but not of mutated PINK1 causes Parkin translocation to mitochondria, even in cells with normal ΔΨ_m. We also show that once at the mitochondria, Parkin is in close proximity to PINK1, but we find no evidence that Parkin catalyzes PINK1 ubiquitination or that PINK1 phosphorylates Parkin. However, co-overexpression of Parkin and PINK1 collapses the normal tubular mitochondrial network into mitochondrial aggregates and/or large perinuclear clusters, many of which are surrounded by autophagic vacuoles. Our results suggest that Parkin, together with PINK1, modulates mitochondrial trafficking, especially to the perinuclear region, a subcellular area associated with autophagy. Thus by impairing this process, mutations in either Parkin or PINK1 may alter mitochondrial turnover which, in turn, may cause the accumulation of defective mitochondria and, ultimately, neurodegeneration in Parkinson''s disease.     

Linear response of mutans streptococci to increasing frequency of xylitol chewing gum use: a randomized controlled trial [ISRCTN43479664]

Background  

Xylitol is a naturally occurring sugar substitute that has been shown to reduce the level of mutans streptococci in plaque and saliva and to reduce tooth decay. It has been suggested that the degree of reduction is dependent on both the amount and the frequency of xylitol consumption. For xylitol to be successfully and cost-effectively used in public health prevention strategies dosing and frequency guidelines should be established. This study determined the reduction in mutans streptococci levels in plaque and unstimulated saliva to increasing frequency of xylitol gum use at a fixed total daily dose of 10.32 g over five weeks.     

Cell-specific adaptation of two flaviviruses following serial passage in mosquito cell culture

West Nile Virus (WNV) is a mosquito-borne flavivirus that was introduced into the U.S. in the New York City area in 1999. Despite its successful establishment and rapid spread in a naive environment, WNV has undergone limited evolution since its introduction. This evolutionary stability has been attributed to compromises made to permit alternating cycles of viral replication in vertebrate hosts and arthropod vectors. Outbreaks of a close relative of WNV, St. Louis encephalitis virus (SLEV), occur in the U.S. periodically and are also characterized by limited genetic change overtime. We measured both phenotypic and genotypic changes in WNV and SLEV serially passaged in mosquito cell culture in order to clarify the role of an individual host cell type in flavivirus adaptation and evolution. Genetic changes in passaged WNV and SLEV were minimal but led to increased relative fitness and replicative ability of the virus in the homologous cell line C6/36 mosquito cells. Similar increases were not measured in the heterologous cell line DF-1 avian cells. These phenotypic changes are consistent with the concept of cell-specific adaptation in flaviviruses.     

Atypical ovarian hyperthecosis in a virilized postmenopausal woman

Ovarian venous concentrations of testosterone (18.7 ng/mL and 8.2 ng/mL) were three to six times higher than the peripheral concentrations (2.8 ng/mL) in a hirsute postmenopausal woman. She had cystic hyperplasia of the endometrium and atypical hyperthecosis of the ovary. Postoperatively, the testosterone levels returned to normal. From the results of the immunoperoxidase reaction, the luteinized stromal cells of the ovaries were the site of increased production of the testosterone and estradiol. By the same technic, these cells were negative for LH but strongly positive for FSH. From these data, the authors conclude that the luteinized cells were the primary source of the excessive testosterone, that the same cells were the direct and indirect (by peripheral testosterone conversion) source of estradiol, that LH was very likely not involved in the process of steroid hormone production, and that FSH may be the trophic stimulus responsible for the functional activity of the luteinized stromal cells in this virilized postmenopausal woman.     

Resuscitation with normal saline (NS) vs. lactated ringers (LR) modulates hypercoagulability and leads to increased blood loss in an uncontrolled hemorrhagic shock swine model

BACKGROUND: Lactated ringers (LR) and normal saline (NS) are used interchangeably in many trauma centers. The purpose of this study was to compare the effects of LR and NS on coagulation in an uncontrolled hemorrhagic swine model. We hypothesized resuscitation with LR would produce hypercoagulability. METHODS: There were 20 anesthetized swine (35 +/- 3 kg) that underwent central venous and arterial catheterization, celiotomy, and splenectomy. After splenectomy blinded study fluid equal to 3 mL per gram of splenic weight was administered. A grade V liver injury was made and animals bled without resuscitation for 30 minutes. Animals were resuscitated with the respective study fluid to, and maintained, at the preinjury MAP until study end. Prothrombin Time (PT), Partial Thromboplastin Time (PTT), and fibrinogen were collected at baseline (0') and study end (120'). Thrombelastography was performed at 0'and postinjury at 30', 60', 90', and 120'. RESULTS: There were no significant baseline group differences in R value, PT, PTT, and fibrinogen. There was no significant difference between baseline and 30 minutes R value with NS (p = 0.17). There was a significant R value reduction from baseline to 30 minutes with LR (p = 0.02). At 60 minutes, R value (p = 0.002) was shorter while alpha angle, maximum amplitude, and clotting index were higher (p < 0.05) in the LR versus the NS group. R value, PT, and PTT were significantly decreased at study end in the LR group compared with the NS group (p < 0.05). Overall blood loss was significantly higher in the NS versus LR group (p = 0.009). CONCLUSIONS: This data indicates that resuscitation with LR leads to greater hypercoagulability and less blood loss than resuscitation with NS in uncontrolled hemorrhagic shock.     

Mediastinal hemangioma arising in setting of partial anomalous pulmonary venous drainage to azygous vein in a 57-year-old woman

Partial anomalous pulmonary venous drainage (PAPVD) to the azygous vein and benign posterior mediastinal hemangioma in adults are both rare entities in isolation. The coexistence of these two lesions in the same patient has not been reported. We describe a unique case of PAPVD to the azygous vein in an adult woman, where the anomalous left inferior pulmonary vein transited first through a large hemangioma, and then eventuated in the azygous vein.     

The three‐year incidence of pulmonary arterial hypertension associated with systemic sclerosis in a multicenter nationwide longitudinal study in France

Objective

An algorithm for the detection of pulmonary arterial hypertension (PAH), based on the presence of dyspnea and the findings of Doppler echocardiographic evaluation of the velocity of tricuspid regurgitation (VTR) and right‐sided heart catheterization (RHC), which was applied in a large multicenter systemic sclerosis (SSc) population, estimated the prevalence of PAH to be 7.85%. The aim of this observational study was to investigate the incidence of PAH and pulmonary hypertension (PH) during a 3‐year followup of patients from the same cohort (the ItinérAIR‐Sclérodermie Study).

Methods

Patients with SSc and without evidence of PAH underwent evaluation for dyspnea and VTR at study entry and during subsequent visits. Patients in whom PAH was suspected because of a VTR of 2.8–3.0 meters/second and unexplained dyspnea or a VTR of >3.0 meters/second underwent RHC to confirm the diagnosis.

Results

A total of 384 patients were followed up for a mean ± SD of 41.03 ± 5.66 months (median 40.92 months). At baseline, 86.7% of the patients were women, and the mean ± SD age of the patients was 53.1 ± 12.0 years. The mean ± SD duration of SSc at study entry was 8.7 ± 7.6 years. After RHC, PAH was diagnosed in 8 patients, postcapillary PH in 8 patients, and PH associated with severe pulmonary fibrosis in 2 patients. The incidence of PAH was estimated to be 0.61 cases per 100 patient‐years. Two patients who exhibited a mean pulmonary artery pressure of 20–25 mm Hg at baseline subsequently developed PAH.

Conclusion

The estimated incidence of PAH among patients with SSc was 0.61 cases per 100 patient‐years. The high incidence of postcapillary PH highlights the value of RHC in investigating suspected PAH.