Intracerebral hemorrhage upregulates Na(+)/myo-inositol cotransporter in the rat brain

Increased frontal white matter diffusion is associated with glial metabolites and psychomotor slowing in HIV

Diffusion-weighted imaging (DWI) measures brain water diffusion that is sensitive to microscopic brain injury. A total of 11 HIV seropositive patients were compared to 14 seronegative subjects using DWI, proton magnetic resonance spectroscopy (1H MRS), and neuropsychological tests. The apparent diffusion coefficient (ADC) was significantly increased in the HIV patients, primarily in the frontal white matter (FWM; +5%, p=0.01). Diffusivity correlated positively with the glial marker myo-inositol (r=0.5, p=0.008) and negatively with cognitive performance (NPZ-8 composite score; r=-0.43, p=0.05). These findings suggest increased brain water diffusion may reflect increased glial activation or inflammation, which in turn, may contribute to the cognitive deficits in HIV patients.

Novel expression of sodium/myo-inositol co-transporter in podocytes in puromycin aminonucleoside nephrosis

BACKGROUND

How podocytes respond to injury is poorly understood, although podocyte injury in the glomerulus has been proposed as the crucial mechanism in the pathogenesis of proteinuria and focal segmental glomerulosclerosis. An increase in sodium/myo-inositol co-transporter (SMIT) transcripts, an osmoprotective gene, has been demonstrated in a variety of brain injury models. In the present study, we investigated SMIT expression in podocytes in experimental nephrosis.

METHODS

Two types of nephrosis were induced in rats: puromycin aminonucleoside (PAN) nephrosis and monoclonal antibody (mAb) 5-1-6 nephropathy. Podocyte injury was morphologically distinct in the former type of nephrosis and limited to a minimum in the latter. SMIT expression in isolated glomeruli was estimated by ribonuclease protection assay. Localization of SMIT-expressing cells in glomeruli was examined by in situ hybridization.

RESULTS

SMIT transcripts in glomeruli increased conspicuously in the nephrotic stage of PAN nephrosis, whereas the transcripts in cortices and medullae did not show significant changes. In situ hybridization revealed that podocytes were predominant cells expressing SMIT in the glomerulus. Significant increase of SMIT mRNA in the glomeruli was detected before the onset of massive proteinuria. In contrast, up-regulation of SMIT expression was not observed in mAb 5-1-6 nephropathy, whose urinary protein levels were comparable with those in the nephrotic stage of PAN nephrosis.

CONCLUSIONS

These findings suggest that SMIT expression in podocytes is not provoked by an effect of massive proteinuria but by extensive cellular injury.