[Karyomegalic interstitial nephritis: an atypical case]

Karyomegalic interstitial nephritis (KIN) is a rare disease entity that was first described by Burry in 1974. The prevalence of this disease is less than 1% and its pathogenesis is unclear. KIN is characterized by chronic tubulointerstitial nephritis associated with enlarged tubular epithelial cell nuclei, which leads to progressive decline of renal function. The disease has no known treatment. Here, we report on a 50-year-old female patient who presented with asymptomatic progressive decline of renal function. Renal biopsy demonstrated chronic tubulointerstitial nephritis with markedly enlarged and hyperchromic nuclei of tubule epithelial cells the hallmark of karyomegalic nephritis. Clinical and pathologic findings of this case are discussed in light of the available literature.

Ultrasound findings of BK polyomavirus-associated nephropathy in renal transplant patients

BK polyomavirus (BKV) is an emerging pathogen in immunocompromised patients. BKV infection occurs in 1-9 % of renal transplants and causes chronic nephropathy or graft loss. Diagnosis of BKV-associated nephropathy (BKVAN) is based on detection of viruria then viremia and at least a tubule-interstitial nephritis at renal biopsy. This paper describes the ultrasound and color Doppler (US-CD) features of BKVAN. Seventeen patients affected by BKVAN were studied using a linear bandwidth 7-12 MHz probe. Ultrasound showed a widespread streak-like pattern with alternating normal echoic and hypoechoic streaks with irregular edges from the papilla to the cortex. Renal biopsy performed in hypoechoic areas highlighted the typical viral inclusions in tubular epithelial cells. Our experience suggests a possible role for US-CD in the non-invasive diagnosis of BKVAN when combined with blood and urine screening tests. US-CD must be performed with a high-frequency linear probe to highlight the streak-like pattern of the renal parenchyma.

[Ultrasound-guided renal biopsy: evaluation of different models of biological simulator]

Percutaneous ultrasound-guided renal biopsy is the gold standard for diagnosis and treatment of renal diseases. Recently, many studies strongly support the role of renal biopsy for the management of small renal mass. The experience of the operator is crucial in reducing the incidence of major complications. The use of simulators can accelerate the learning curve in those individuals who train in renal biopsy. We describe four simple and affordable phantoms for renal biopsy. The first two simulators were constructed by a porcine kidney wrapped in perirenal fat or covered by a flap of abdominal skin. The third simulator was constructed by embedding a porcine kidney in a turkey breast and olives to simulate the presence of small tumors. For the fourth model, we used the loin of a pork. Given the encouraging results of our in vitro study, we believe that simulators allow trainees to familiarize themselves with the handling of the equipment in an environment that is risk-free when compared to the clinical scenario.

[Acute anemia in high digestive hemorrhage. Margins of security for their handling without transfusion of red globules]

Red cells transfusion in the patient with acute hemorrhage, must be evaluated in a risk/benefit rate context. The present tendencies appoint that the use of the hematocrit "magic" number is unsafe and uncertain to decide a red cell transfusion. We have conducted a prospective randomized and controlled trial in 60 patients with acute digestive hemorrhage without haemodynamic failure. We realized two groups: 1) control group: the target of transfusion in these patients was the hematocrit value of > or = 28%. 2) treatment group: these patients were supported with normovolemic haemodilution with crystalloid solutions until a hematocrit value of 21%. All patients have endoscopic diagnosis and they went evaluated across the study with clinic and laboratory controls. Both groups were significative differences in the hematocrit value. We did not see differences between the groups in the hospital stay neither the rate of organs failure. We find difference between the groups in the amount of red cell units (0.61 +/- 0.87 vs. 2.14 +/- 1.10; treatment and control respectively, P < 0.001). The APACHE score was greater in the treatment group. This supports that the oldest patients, who probably have least physiologic reserve, could be treated without complications. Acute hemorrhage-normovolemic haemodilution-digestive hemorrhage transfusion.

Intracellular calcium signalling and vascular reactivity in Bartter's syndrome

We investigated patients affected by Bartter's syndrome in the attempt to localize the intracellular defect mediating the reduced intracellular Ca2+ mobilization that may be responsible for the decreased vascular reactivity characteristic of Bartter's syndrome. Using the formylmethionyl-leucyl-phenylalanine (fMLP) receptor system, which causes, intracellular calcium release, we investigated fMLP-stimulated intracellular inositol 1,4,5-trisphosphate (IP3) production as well as the number and affinity of fMLP receptors in neutrophils from Bartter's syndrome patients and healthy controls. Scatchard plot analysis of radioactive fMLP binding to neutrophils indicated that there were no differences in either cell receptor number and affinity for ligand between healthy controls (n = 5) and patients with Bartter's syndrome (n = 5): 6,151 +/- 1,431 vs. 7,112 +/- 2,566 receptors/cell; K(D): 0.446 +/- 0.14 vs. 0.454 +/- 0.09 pM of fMLP. 5- and 10-second fMLP-stimulated intracellular IP3 production was instead reduced in patients affected by Bartter's syndrome: 2.479 +/- 1.07 vs. 4.073 +/- 1.04 nmol/10(7) cells at 5 s (n = 8; p < 0.01); 1.673 +/- 0.741 vs. 3.766 +/- 1.348 nmol/10(7) cells at 10 s (n = 8; p < 0.005). The results of this study indicate that the anomaly of intracellular calcium mobilization in patients with Bartter's syndrome arises from a defect at the postreceptor level. The anomalous calcium signalling that takes place in Bartter's syndrome may provide a mechanism for the hyporesponsiveness to pressor stimuli characteristic of these patients.

Nifedipine can preserve renal function in patients undergoing aortic surgery with infrarenal crossclamping

Sixteen patients diagnosed with an aneurysm of abdominal aorta or Leriche disease underwent elective aortic surgery involving crossclamping of infrarenal aorta (ICC). These patients were randomized into two equal groups and 8 patients were infused with nifedipine starting from the isolation of aorta until the end of surgery (group A) while another 8 patients were infused with low-dose dopamine (group B) over the same surgical course. Plasma endothelin (ET) was measured before the induction of anesthesia, at the beginning and at the end of the clamp period and at the end of the operation. Intraoperatively, creatinine clearance and urinary excretion of PGE2, 6-keto PGF1 alpha and TxB2 were also determined before, during and after aortic crossclamping. Preoperative GFR as well as preinduction cardiac index (CI) and pulmonary capillary wedge pressure (PCWP) of the two groups did not differ. During cross-clamping plasma ET rose significantly in both groups. However, after clamp removal, plasma ET decreased in group A while it remained elevated in group B. Urinary excretion of TxB2, PGE2 and 6-keto PGF1 alpha increased during clamp in both groups, but the ratio of PGE2 + 6-keto PGF1 alpha/TxB2 during and after clamp was significantly higher in group A than in B. Postclamp creatinine clearance decreased in group B, and increased in group A; postoperative value of GFR was unchanged in group A and decreased significantly in group B. In conclusion, infusion of nifedipine, in contrast to dopamine, prevented the decrease of GFR in patients undergoing aortic surgery. This effect could be mediated by a nifedipine modulation of ET vascular synthesis and/or a preferential renal synthesis of vasodilating prostanoids.

Endothelium-derived vasoactive substances in Bartter's syndrome

An imbalance between endothelium-derived vasoactive substances such as endothelin and endothelium-derived nitric oxide (NO) might be viewed as a possible determinant of vascular hyporeactivity. To check this possibility the authors evaluated the role of endothelin and NO in the reduced vascular reactivity of Bartter's syndrome. Plasma immunoreactive endothelin (22.07 +/- 7.06 vs 13.80 +/- 1.43 pmol/L, P < 0.011), urinary excretion of NO2- (0.28 +/- 0.10 vs 0.15 +/- 0.02, mumol/mumol of urinary creatinine, P < 0.01) and NO3- (0.17 +/- 0.07 vs 0.09 +/- 0.02 mumol/mumol of urinary creatinine, P < 0.011), and forearm resting blood flow (FRBF) (6.67 +/- 1.69 vs 4.30 +/- 0.38 mL/m'/100 mL, P < 0.005) were increased in patients with Bartter's syndrome in comparison with normal controls (C). No difference in postischemic maximal FBF was found (34.14 +/- 4.67 vs 31.35 +/- 2.86 mL/minute/100 mL), while patients showed a slower recovery after peak flow (PF) (77.57 +/- 61.35 vs 9.42 +/- 3.69 seconds, P < 0.013). Higher plasma endothelin supports the defect in vascular reactivity of Bartter's syndrome already shown for angiotensin II and norepinephrine and is in keeping with the altered intracellular calcium signaling previously demonstrated by the authors in this syndrome. The increased excretion of NO2- and NO3- in this syndrome, together with the higher FRBF and the slower recovery of the FBF and PF, argues in favor of an increased NO synthesis in Bartter's syndrome and of assigning it a role in the vascular hyporeactivity of Bartter's syndrome.