Regulation of presynaptic neurotransmission by macroautophagy

mTOR is a regulator of cell growth and survival, protein synthesis-dependent synaptic plasticity, and autophagic degradation of cellular components. When triggered by mTOR inactivation, macroautophagy degrades long-lived proteins and organelles via sequestration into autophagic vacuoles. mTOR further regulates synaptic plasticity, and neurodegeneration occurs when macroautophagy is deficient. It is nevertheless unknown whether macroautophagy modulates presynaptic function. We find that the mTOR inhibitor rapamycin induces formation of autophagic vacuoles in prejunctional dopaminergic axons with associated decreased axonal profile volumes, synaptic vesicle numbers, and evoked dopamine release. Evoked dopamine secretion was enhanced and recovery was accelerated in transgenic mice in which macroautophagy deficiency was restricted to dopaminergic neurons; rapamycin failed to decrease evoked dopamine release in the striatum of these mice. Macroautophagy that follows mTOR inhibition in presynaptic terminals, therefore, rapidly alters presynaptic structure and neurotransmission.

Does JC polyomavirus cause nephropathy in renal transplant patients?

INTRODUCTION

BK polyomavirus (BKV) reactivation characterized by active viruria occurs in 23%-57% of renal allograft recipients and BKV-associated nephropathy in as many as 8% of renal allograft recipients. Only a few cases of nephritis have been attributed to JC polyomavirus (JCV) with limited information about JCV replication and its impact on graft function and survival of kidney transplant patients. We sought to determine the prevalence of BKV and JCV replication, the risk factors associated with viral reactivation, and their implications for the development of polyomavirus nephropathy (PVN) among renal transplant patients.

MATERIALS AND METHODS

The study included 186 kidney transplant recipients who were transplanted between 2005 and 2009 with a 1-year follow-up. If the urine polymerase chain reaction (PCR) was positive, we performed a PCR on blood. If this was positive or renal dysfunction was present, we performed a renal biopsy.

RESULTS

Viruria was positive in 72 cases (39%) and viremia in 12 (6.5%); including, 3 patients (1.6%) who developed PVN. In the patients with viruria, BKV was detected in 47% and JCV in 46%; both were detected in 7%, although the combination of viremia and nephropathy were caused by BKV in all cases.

CONCLUSION

In renal transplant patients, the incidence of BKV and JCV viruria was similar, although in our series the JCV serotype did not cause viremia or PVN. Our experience suggested that JCV did not have the ability to cause PVN.

Renal transplantation in old recipients from expanded criteria donors selected by kidney biopsy

BACKGROUND

In Spain, the number of ideal kidney transplant donors has fallen, with at the same time an increase in the number of older recipients on the waiting list.

AIM

To analyze the results of expanded criteria cadaveric donor kidney transplants into older recipients using grafts selected by kidney biopsy.

PATIENTS AND METHODS

We studied 360 kidney transplant recipients who had been followed to December 2009: 180 in the study group and 180 in a control group composed of younger patients who received grafts from non-expanded criteria donors between 1999 and 2006. A paraffin-embedded kidney biopsy was evaluated by the percentages of sclerosed glomeruli, arteriolar hyalinosis, intimal wall thickening, interstitial fibrosis, and tubular atrophy.

RESULTS

Significant differences were observed in donor age (63.50±5.46 vs 31.90±13.29 years; P<.001) and recipient age (58.40±8.80 vs 40.71±13.23 years; P<.001). Donor renal function was significantly worse among the expanded criteria group (90.80 vs 108.11 mL/min/1.73 m2; P=.006), remaining so over time in the recipient (at 1 year: 42.08 vs 63.71 [P<.001]; at 3 years: 41.25 vs 62.31 [P<.001], and at 7 years: 38.17 vs 64.18 [P<.001]). Censored 7-year graft survivals were 73% versus 87% (P<.001) with similar patient survivals (90.5% vs 95%; P=.39).

CONCLUSIONS

Selection of expanded criteria donors by kidney biopsy resulted in good renal function as well as graft and patient survivals at 7 years in older recipients.