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Dose-response expression of kidney injury molecule-1 (KIM-1) gene in kidney cortex and its correlation with morphology and traditional biomarkers of nephrotoxicity (plasma creatinine and blood urea nitrogen, BUN) or segment-specific marker of proximal tubule injury (kidney glutamine synthetase, GSK) were studied in male rats treated with proximal tubule segment-specific nephrotoxicants. These included hexachloro-1:3-butadiene (HCBD, S(3) segment-specific), potassium dichromate (chromate, S(1)-S(2) segment-specific), and cephaloridine (Cph, S(2) segment-specific). Rats were treated with a single intraperitoneal (ip) injection of HCBD 25, 50, and 100 mg/kg, subcutaneous (sc) injection of chromate 8, 12.5, and 25 mg/kg; or ip injection of Cph 250, 500, and 1,000 mg/kg. KIM-1 gene showed a dose-dependent up-regulation induced by all segment-specific nephrotoxicants. Interestingly, magnitude of the up-regulation reflected the severity of microscopic tubular changes (degeneration, necrosis, and regeneration). Even low-severity microscopic observations were evidenced by significant gene expression changes. Furthermore, KIM-1 showed significant up-regulation even in the absence of morphological changes. In contrast, traditional and specific markers demonstrated low sensitivity or specificity. In conclusion, this study suggested KIM-1 as a sensitive molecular marker of different levels of tubular injury, and it is likely to represent a potential tool for early screening of nephrotoxicants.

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The correspondence between histopathological findings and segment-specific biomarkers was investigated in rats treated with segment-specific nephrotoxicants. Male Wistar rats were treated with a single injection of K 2 Cr 2 O 7 (25 mg/kg sc in saline), cis-Pt (10 mg/kg ip in buffered MSO) or HCBD (100 mg/kg ip in corn oil). Twenty-four and 48 hours after treatment, the rats were sacrificed and the kidneys were drawn for histopathological and biochemical evaluation, i.e., GS activity in renal cortex and PAH uptake in renal cortical slices. Histopathological findings show that cis-Pt and HCBD cause diffuse necrosis of S 3 segment of proximal tubules in the outer stripe of outer medulla, respectively. On the contrary, K 2 Cr 2 O 7 damages exclusively S 1 -S 2 segments, inducing vacuolization at 24 hr and diffuse necrosis at 48 hr after treatment. GS activity in renal tissue is significantly decreased after HCBD and cis-Pt, but not K 2 Cr 2 O 7 treatment. In contrast, PAH uptake is significantly reduced by K 2 Cr 2 O 7 , but not by cis-Pt or HCBD treatment (even if HCBD causes a slight decrease 48 hr after treatment). The evidence of this study confirms the high specificity of GS activity as marker of S 3 segment injury, that PAH uptake is prevalently active in the S 1 -S 2 segments, and that there is complete correspondence among segment-specific nephrotoxicants, biomarkers of segment-specific damage, and histopathological findings.

The present data suggest that in the guinea pig ileum during in vitro ischemia/reperfusion, NR1 protein levels increase. Such event may rely upon posttranscriptional events involving NR1 phosphorylation by PKC. Increased NR1 levels may, at least in part, explain the ability of NMDA receptors to modulate a positive feedback on ischemia/reperfusion-induced glutamate overflow.

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Severe pallid breath-holding spells (BHSs) are based on parasympathetic hyperactivity, leading to cardiac asystole, pallor, brain ischemia, loss of consciousness, and reflex anoxic seizures. In recent years, an increasing number of patients with severe pallid BHSs have been successfully treated with pacemaker implantation. We present the case of a 13-month-old girl suffering from repeated severe pallid BHSs, causing asystole, loss of consciousness, and generalized anoxic seizures. She underwent treatment with oral glycopyrrolate, an anticholinergic drug, and an oral retard preparation of theophylline. The aim of the treatment was to decrease cardiac inhibition with glycopyrrolate and to bring about a positive chronotropic effect with theophylline. In our case, the combined therapy was effective in suppressing syncope and reflex anoxic seizures associated with BHSs This avoided the need for ventricular pacemaker implantation.

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