Presence of Extracellular Alpha-Synuclein Aggregates Trigger Astrocytic Degeneration Through Enhanced Membrane Rigidity and Deregulation of Store-Operated Calcium Entry (SOCE) into the Endoplasmic Reticulum

α-Synuclein has a critical role in Parkinson's disease, but the mechanism of how extracellular α-synuclein aggregates lead to astrocytic degeneration remains unknown. Our recent study in astrocytes highlighted that α-synuclein aggregates undergo lower endocytosis than the monomeric-form, even while displaying a higher impact on glutathione-machinery and glutamate-metabolism under sublethal conditions. As optimal intracellular calcium levels are essential for these functions, we aimed to study the effect of extracellular α-synuclein aggregates on ER calcium entry. We assessed the association of extracellular aggregated-α-synuclein (WT and A30P/A53T double-mutant) with the astrocytic membrane (lipid rafts) and studied its effects on membrane fluidity, ER stress, and ER calcium refilling in three systems-purified rat primary midbrain astrocyte culture, human iPSC-derived astrocytes, and U87 cells. The corresponding timeline effect on mitochondrial membrane potential was also evaluated. Post-24 h exposure to extracellular WT and mutant α-synuclein aggregates, fluorescence-based studies showed a significant increase in astrocyte membrane rigidity over control, with membrane association being significantly higher for the double mutant aggregates. α-Synuclein aggregates also showed preferentially higher association with lipid rafts of astrocytic membrane. A simultaneous increase in ER stress markers (phosphorylated PERK and CHOP) with significantly higher SOCE was also observed in aggregate-treated astrocytes, with higher levels for double mutant variant. These observations correlate with increased expression of SOCE markers, especially Orai3, on plasma membrane. Alterations in mitochondrial membrane potential were only noted post-48 h of exposure to α-synuclein aggregates. We therefore suggest that in astrocytes, α-synuclein-aggregates preferentially associate with lipid rafts of membrane, altering membrane fluidity and consequently inducing ER stress mediated by interaction with membrane SOCE proteins, resulting in higher Ca2+ entry. A distinct cascade of events of sequential impairment of ER followed by mitochondrial alteration is observed. The study provides novel evidence elucidating relationships between extracellular α-synuclein aggregates and organellar stress in astrocytes and indicates the therapeutic potential in targeting the association of α-synuclein aggregates with astrocytic membrane.

A rapid and simple resazurin assay to detect minimum inhibitory concentrations of first-line drugs for Mycobacterium tuberculosis isolated from cerebrospinal fluid

OBJECTIVES

Central nervous system tuberculosis (CNS-TB) is a devastating manifestation of TB. The most common form of CNS-TB is tuberculous meningitis. Drug-resistant TB poses a major threat to the control of TB worldwide. Timely treatment dramatically improves the outcome. Colorimetric techniques for drug susceptibility testing based on the oxidation-reduction principle give results quick and are less expensive. The objectives of this study were to compare the susceptibility of Mycobacterium tuberculosis isolated from cerebrospinal fluid to four first-line drugs using the MGIT automated mycobacterial detection system and the resazurin assay (RA) as well as to estimate the minimum inhibitory concentrations (MICs) by RA.

METHODS

A total of 42 M. tuberculosis isolates were analysed for their susceptibilities by MGIT and RA.

RESULTS

Of the 42 isolates, 35 gave concordant results with both methods. Agreement between the two tests for streptomycin and rifampicin was 100% with a Fleiss' kappa (κ) value of 1, whereas for isoniazid and ethambutol agreement was 92.86% and 90.48%, respectively, with κ values of 0.853 and 0.738.

CONCLUSION

The RA appears to be a good alternative to the automated MGIT technique in resource-limited settings.

Mitochondrial functions of RECQL4 are required for the prevention of aerobic glycolysis-dependent cell invasion

Germline mutations in RECQL4 helicase are associated with Rothmund-Thomson syndrome, which is characterized by a predisposition to cancer. RECQL4 localizes to the mitochondria, where it acts as an accessory factor during mitochondrial DNA replication. To understand the specific mitochondrial functions of RECQL4, we created isogenic cell lines, in which the mitochondrial localization of the helicase was either retained or abolished. The mitochondrial integrity was affected due to the absence of RECQL4 in mitochondria, leading to a decrease in F1F0-ATP synthase activity. In cells where RECQL4 does not localize to mitochondria, the membrane potential was decreased, whereas ROS levels increased due to the presence of high levels of catalytically inactive SOD2. Inactive SOD2 accumulated owing to diminished SIRT3 activity. Lack of the mitochondrial functions of RECQL4 led to aerobic glycolysis that, in turn, led to an increased invasive capability within these cells. Together, this study demonstrates for the first time that, owing to its mitochondrial functions, the accessory mitochondrial replication helicase RECQL4 prevents the invasive step in the neoplastic transformation process.

No demonstrable benefit for coronal alignment outcomes in PSI knee arthroplasty: A systematic review and meta-analysis

AIM

A systematic review and meta-analysis of clinical studies assessing alignment outcomes in patient-specific instrumented (PSI) knee arthroplasty was conducted.

MATERIALS AND METHODS

PRISMA compliant data was extracted from literature databases up to January 2014.

RESULTS

Twenty-six studies met the inclusion criteria, reporting a total of 1792 knees. Twenty-three studies reported alignment outcomes in the coronal plane, 11 in the sagittal plane. In all but three series, MRI was the preoperative imaging modality. Range of mean postoperative alignment (hip-knee-ankle [HKA] angle) was 176.5 to 181.70. The proportion of three degrees of outliers showed an overall mean of 18.6%. In total, fifteen studies compared alignment outcomes between standard and PSI. From these, four studies showed significantly higher accuracy of coronal plane alignment with PSI (HKA angle). Meta-analysis of seven high-quality comparative studies demonstrated no significant increased accuracy in postoperative mechanical axis (HKA angle) with PSI. Subgroup meta-analysis of both femoral and tibial rotation was not feasible due to a low number of inclusive high-quality series.

CONCLUSIONS

PSI knee arthroplasty is shown not to confer increased accuracy in reconstituting the postoperative mechanical axis. Further studies are required to demonstrate both clinical and radiological alignment outcomes in PSI knee arthroplasty with focus upon tibial and femoral rotation.

Protective effect of curcuminoids on age-related mitochondrial impairment in female Wistar rat brain

The present study demonstrated the neuroprotective effect of curcuminoids, the active polyphenols of Curcuma longa (L.) rhizomes on mitochondrial dysfunctioning in middle aged and aged female Wistar rat brain. Rats were orally treated with curcuminoids (100 mg/kg) for 3 months and their brain was collected for evaluation of mitochondrial enzymes and complexes activity, ultra structural changes in mitochondria, neuronal nitric oxide synthase (nNOS) protein expression, adenosine triphosphate (ATP) and lipofuscin content. Significant alterations were observed in all the tested parameters in highly aged rat brain when compared with young control. Long term curcuminoids administration prevented this age associated loss of mitochondrial enzymes and complexes activity in middle aged rat brain except for malate dehydrogenase, Complex II and IV activity when compared with young control. Among aged rats, curcuminoids treatment specifically elevated isocitrate and NADH dehydrogenase, cytochrome c oxidase, Complex I and total ATP content. A significant down-regulation of nNOS protein expression along with reduced lipofuscin content was also observed in curucminoids treated middle aged and aged rats. Thus, it was suggested that curcuminoids may act as a putative drug candidate for the prevention of deleterious effects of ageing and age associated neurodegenerative disorders through amelioration of aberrant mitochondrial functioning.

Resistance pattern in drug-resistant pulmonary tuberculosis

BACKGROUND

Drug-resistant tuberculosis is an important issue for public health. There is a rise in the trend of drug-resistant tuberculosis, especially multi drug resistance (MDR), in different parts of world, India being one of the high burden countries. This study is undertaken to assess the various patterns of resistance among confirmed drug resistant pulmonary tubercular patients and to initiate second line anti tubercular treatment.

AIMS AND OBJECTIVES

To assess various resistance patterns among confirmed drug resistant pulmonary tubercular patients and for the initiation of appropriate drug regimens in our setup.

STUDY DESIGN

An observational prospective study.

MATERIALS AND METHODS

This study was conducted at Rajiv Gandhi Institute of Chest Diseases, Bangalore between January 2005 and November 2010. A total of 309 drug resistant tuberculosis cases were studied. Sputum culture and drug sensitivity were carried out at National Tuberculosis Institute. Drug sensitivity testing done for all first line drugs, except pyrazinamide, by using LJ media.

RESULTS

In this study, out of 309 patients, MDR pattern was observed in 224 (72%), of which 20 (6.47%) had resistance only to isoniazid (INH) and rifampicin (RMP), 58 (18.7%) had resistance to INH, RMP, and either of the other first line drugs streptomycinor ethambutol and 146 (47.25%) had resistance to all first line drugs. Poly drug resistance pattern was observed in 72 (23.3%) and Mono drug resistance in 13 (4.2%).

CONCLUSION

In the present study the most common pattern observed is MDR with predominant resistance to INH. There is a rise in the number of drug resistant tuberculosis cases, especially MDR. Hence close monitoring of drug resistant pattern is required to formulate designs of different regimens in the treatment of drug resistant tuberculosis; especially MDR-TB based on accredited laboratory reports, in a specialized center which is very much essential for the betterment of the patients and the community.

Pattern of drug-resistance and treatment outcome in multidrug-resistant pulmonary tuberculosis

AIMS AND OBJECTIVES

To study the pattern of drug-resistance and treatment outcomes among patients with confirmed multidrug-resistant pulmonary tuberculosis (MDR-PTB).

METHODS

A prospective study was conducted at Rajiv Gandhi Institute of Chest Diseases, Bengaluru, Karnataka, India. Between January 2005 and December 2008, 224 confirmed MDR-PTB cases were studied for various drug-resistance patterns, and their treatment outcomes were analysed until November 2010. Sputum culture and drug sensitivity tests (DST) were carried out at National Tuberculosis Institute, Bengaluru; DST was done for all first-line drugs except pyrazinamide.

RESULTS

Of the 224 MDR-PTB patients, 146 (65.2%) were resistant to all first-line drugs, 39 (17.4%) to isoniazid, rifampicin and streptomycin; 19 (8.5%) to isoniazid, rifampicin and ethambutol; and 20 (8.9%) to isoniazid and rifampicin. Among them, 145 (64.7%) patients were cured, 5 (2.2%) had treatment-failure, 10 (4.4%) died, and 64 (28.5%) defaulted. Among 145 cured cases, 100 (69%) were resistant to all first-line drugs, 23 (16%) to isoniazid, rifampicin and streptomycin, 11(8%) to isoniazid, rifampicin and ethambutol, and 11(8%) to isoniazid and rifampicin.

CONCLUSIONS

The most common pattern observed in this study was resistance to all four first-line drugs followed by resistance to isoniazid, rifampicin and streptomycin. Patients resistant to all first-line drugs had early sputum culture conversion and better cure rate as compared to other resistance patterns.

Dysmyelinating neuropathy in benign form of megalencephalic leukoencephalopathy with subcortical cysts: a novel observation from south India

A 37-year-old gentleman presented with macrocephaly since early childhood and progressive impairment of motor and cognitive functions. Magnetic resonance imaging revealed extensive white matter involvement and frontotemporal subcortical cysts. Absent ankle jerk and abnormal nerve conduction study raised a possibility of associated peripheral neuropathy. Sural nerve biopsy was suggestive of dysmyelinating neuropathy. This report serves to expand the clinical spectrum of this rare leukodystrophy.