Citations

While the subcellular organisation of mitochondria is likely to influence many aspects of cell physiology, its molecular control is poorly understood. Here, we have investigated the role of the retrograde motor protein complex, dynein-dynactin, in mitochondrial localisation and morphology. Disruption of dynein function, achieved in HeLa cells either by over-expressing the dynactin subunit, dynamitin (p50), or by microinjection of an anti-dynein intermediate chain antibody, resulted in (a) the redistribution of mitochondria to the nuclear periphery, and (b) the formation of long and highly branched mitochondrial structures. Suggesting that an alteration in the balance between mitochondrial fission and fusion may be involved in both of these changes, overexpression of p50 induced the translocation of the fission factor dynamin-related protein (Drp1) from mitochondrial membranes to the cytosol and microsomes. Moreover, a dominant-negative-acting form of Drp1 mimicked the effects of p50 on mitochondrial morphology, while wild-type Drp1 almost completely restored normal mitochondrial distribution in p50 over-expressing cells. Thus, the dynein/dynactin complex plays an unexpected role in the regulation of mitochondrial morphology in living cells, by controlling the recruitment of Drp1 to these organelles.

ABSTRACT Introduction The optimal approach for identification and evaluation of the sexual problems in men and women in primary care or general medicine practice has not been consensed. Aim To provide recommendations/guidelines concerning state-of-the-art knowledge for clinical evaluation and management strategies in the evaluation and treatment of sexual dysfunction in men and women, emphasizing evidence-based medicine and a patient-centered framework. Methods An International Consultation in collaboration with the major urology and sexual medicine associations assembled over 200 multidisciplinary experts from 60 countries into 17 committees. Committee members established specific objectives and scopes for various male and female sexual medicine topics. The recommendations concerning state-of-the-art knowledge in the respective sexual medicine topic represent the opinion of experts from five continents developed in a process over a 2-year period. Concerning the Clinical Evaluation and Management Strategies Committee, there were 12 experts from five countries. Main Outcome Measure Expert opinion was based on grading of evidence-based medical literature, widespread internal committee discussion, public presentation and debate. Results Three concepts underlie sexual medicine management: (i) adoption of a patient-centered framework for evaluation and treatment; (ii) application of the principles of evidence-based medicine in diagnostic and treatment planning; and (iii) use of a unified management approach in men and women. When taken together, these three principles provide a balanced and integrated approach to sexual dysfunction management. Common algorithms for diagnosis and management of men and women with sexual dysfunction, brief sexual symptom checklists, basics in history and physical examination, indications for specialized referral and development of a follow-up strategy are presented. Conclusions More research is needed in understanding the role of evidence-based and patient-centered medicine in the clinical evaluation and management strategies of men and women with sexual dysfunction.

In normal human skin fibroblasts (HSFs), fluorescent glycosphingolipid analogues are endocytosed and sorted into two pools, one that is recycled to the plasma membrane and one that is transported to the Golgi complex. Here, we investigated glycosphingolipid recycling in Niemann-Pick type A and C lipid storage disease fibroblasts (NPFs). Cells were incubated with a fluorescent analogue of lactosylceramide (LacCer) at 16°C to label early endosomes (EEs), shifted to 37°C, and lipid recycling was quantified. Using dominant negative rabs, we showed that, in normal HSFs, LacCer recycling was rapid (t1/2∼8 min) and mainly rab4-dependent. In NPFs, LacCer recycling was delayed (t1/2∼30–40 min), and rab4-dependent recycling was absent, whereas rab11-dependent recycling predominated. Transferrin recycling via the rab4 pathway was similarly perturbed in NPFs. Compared with normal HSFs, EEs in NPFs showed high cholesterol levels and an altered organization of rab4. In vitro extraction of rab4 (but not rab11) with GDP dissociation inhibitor was severely attenuated in NPF endosomal fractions. This impairment was reversed with cholesterol depletion of isolated endosomes or with high-salt treatment of endosomes. These data suggest that abnormal membrane recycling in NPFs results from specific inhibition of rab4 function by excess cholesterol in EEs.

ABSTRACTIsoniazid (INH), a front-line antituberculosis agent, is activated by mycobacterial catalase-peroxidase KatG, converting INH into bactericidal reactive species. Here we investigated the requirements and the pathway of nitric oxide (NO˙) generation during oxidative activation of INH byMycobacterium tuberculosisKatG in vitro. We also provide in vivo evidence that INH-derived NO˙ can inhibit key mycobacterial respiratory enzymes, which may contribute to the overall antimycobacterial action of INH.