SEM-EDX linear scanning: a new tool for morpho-compositional analysis of growth bands in urinary stones

The genesis and growth of calculi are imprinted in their structure, so the pathogenesis of lithiasis could potentially be read via proper analytical techniques. In this study, electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) is used to obtain a description of the morphology and compositional structure of a single bladder stone. This technique establishes the chemical and crystalline architecture of the urolith to assess the effect of the chemical environment on its growth. Scanning electron microscopy-backscattered electrons (SEM-BSE) images clearly show that the stone has a multilayered structure. These layers and Liesegang ring-like structures are characterized by one predominant chemical component but also by slighter compositional changes. The mean crystalline components are determined by X-ray diffraction (DRX), infrared spectroscopy (FT-IR), and Raman analysis (RMN). Elemental analysis along a radial trajectory of the calculus by EDX linear scanning (EDX-LS) also reveals the compositional structure of the layers and the spatial distribution of the main chemical components. EDX-LS data processing reveals concentration profiles that clearly show morpho-compositional growth bands, which correspond to precipitation waves and urinary concentration peaks. The width of the growth bands is independent of the radial position, layer, and element analyzed. We conclude that the bands observed are a consequence of slight changes in the biochemical composition of the urine and consequently reflect a short-term biological cycle of the renal system. This non-specific growth rate suggests that stone formation is a kinetically controlled phenomenon in which promoters of crystal cluster aggregation may have played a key role.

Risk factors for graft loss and mortality after renal transplantation according to recipient age: a prospective multicentre study

BACKGROUND

To describe the causes of graft loss, patient death and survival figures in kidney transplant patients in Spain based on the recipient's age.

METHODS

The results at 5 years of post-transplant cardiovascular disease (CVD) patients, taken from a database on CVD, were prospectively analysed, i.e. a total of 2600 transplanted patients during 2000-2002 in 14 Spanish renal transplant units, most of them receiving their organ from cadaver donors. Patients were grouped according to the recipient's age: Group A: <40 years, Group B: 40-60 years and Group C: >60 years. The most frequent immunosuppressive regimen included tacrolimus, mycophenolate mofetil and steroids.

RESULTS

Patients were distributed as follows: 25.85% in Group A (>40 years), 50.9% in Group B (40-60 years) and 23.19% in Group C (>60). The 5-year survival for the different age groups was 97.4, 90.8 and 77.7%, respectively. Death-censored graft survival was 88, 84.2 and 79.1%, respectively, and non death-censored graft survival was 82.1, 80.3 and 64.7%, respectively. Across all age groups, CVD and infections were the most frequent cause of death. The main causes of graft loss were chronic allograft dysfunction in patients <40 years old and death with functioning graft in the two remaining groups. In the multivariate analysis for graft survival, only elevated creatinine levels and proteinuria >1 g at 6 months post-transplantation were statistically significant in the three age groups. The patient survival multivariate analysis did not achieve a statistically significant common factor in the three age groups.

CONCLUSIONS

Five-year results show an excellent recipient survival and graft survival, especially in the youngest age group. Death with functioning graft is the leading cause of graft loss in patients >40 years. Early improvement of renal function and proteinuria together with strict control of cardiovascular risk factors are mandatory.

Mutations in the chloride-bicarbonate exchanger gene AE1 cause autosomal dominant but not autosomal recessive distal renal tubular acidosis

Primary distal renal tubular acidosis (dRTA) is characterized by reduced ability to acidify urine, variable hyperchloremic hypokalemic metabolic acidosis, nephrocalcinosis, and nephrolithiasis. Kindreds showing either autosomal dominant or recessive transmission are described. Mutations in the chloride-bicarbonate exchanger AE1 have recently been reported in four autosomal dominant dRTA kindreds, three of these altering codon Arg589. We have screened 26 kindreds with primary dRTA for mutations in AE1. Inheritance was autosomal recessive in seventeen kindreds, autosomal dominant in one, and uncertain due to unknown parental phenotype or sporadic disease in eight kindreds. No mutations in AE1 were detected in any of the autosomal recessive kindreds, and analysis of linkage showed no evidence of linkage of recessive dRTA to AE1. In contrast, heterozygous mutations in AE1 were identified in the one known dominant dRTA kindred, in one sporadic case, and one kindred with two affected brothers. In the dominant kindred, the mutation Arg-589/Ser cosegregated with dRTA in the extended pedigree. An Arg-589/His mutation in the sporadic case proved to be a de novo mutation. In the third kindred, affected brothers both have an intragenic 13-bp duplication resulting in deletion of the last 11 amino acids of AE1. These mutations were not detected in 80 alleles from unrelated normal individuals. These findings underscore the key role of Arg-589 and the C terminus in normal AE1 function, and indicate that while mutations in AE1 cause autosomal dominant dRTA, defects in this gene are not responsible for recessive disease.

Aminoglycoside-associated Fanconi's syndrome: an underrecognized entity

The Fanconi syndrome is an array of multiple proximal renal tubular dysfunctions occurring in association with several exogenous toxins, such as aminoglycosides. These antibiotics remain the drugs of choice in most gram-negative infections, but nephrotoxicity is the main drawback for them. Furthermore, the nephrotoxic effects may be overlooked with routine analyses. With the purpose of making physicians aware of this underrecognized complication, we are reporting here 3 cases of Fanconi's syndrome related to the administration of high-dose aminoglycosides (ranging from 3.6 to 15 g) with normal serum urea nitrogen and creatinine levels. The pattern of aminoaciduria demonstrated high increases in neutral amino acids, followed by dibasic and near-normal acidic amino acids. We also report the urinary excretion rates of total protein and beta2-microglobulin and protein electrophoresis results. We compared these cases with others reported in the literature.

Gitelman's variant of Bartter's syndrome, inherited hypokalaemic alkalosis, is caused by mutations in the thiazide-sensitive Na-Cl cotransporter

Maintenance of fluid and electrolyte homeostasis is critical for normal neuromuscular function. Bartter's syndrome is an autosomal recessive disease characterized by diverse abnormalities in electrolyte homeostasis including hypokalaemic metabolic alkalosis; Gitelman's syndrome represents the predominant subset of Bartter's patients having hypomagnesemia and hypocalciuria. We now demonstrate complete linkage of Gitelman's syndrome to the locus encoding the renal thiazide-sensitive Na-Cl cotransporter, and identify a wide variety of non-conservative mutations, consistent with loss of function alleles, in affected subjects. These findings demonstrate the molecular basis of Gitelman's syndrome. We speculate that these mutant alleles lead to reduced sodium chloride reabsorption in the more common heterozygotes, potentially protecting against development of hypertension.

Evaluation of complications due to percutaneous renal biopsy in allografts and native kidneys with color-coded Doppler sonography

We studied 142 consecutive percutaneous renal biopsies (puncturing on 73 allografts and 69 native kidneys) which were performed under continuous ultrasonic guidance, on 133 adult patients. The patients were monitored, at least, during the next 24 hours. We compared the complication rate for biopsies recording clinical and biochemical data and, the day after the biopsy, the kidney was examined with a color-coded Doppler sonography (CCDS): in real-time survey of the kidney and with spectral wave form analysis. The diagnosis of arteriovenous (AV) fistula was achieved detecting increased color saturation toward white, high peak systolic flow velocity and low resistive index in the supplying artery. Three procedures were excluded of the analyses because of incomplete data recorded, although none of them showed any remarkable complication. There was a 94.3% rate of successful biopsies. The mean +/- SEM number of glomeruli under light microscopic examination was 8.5 +/- 0.6. Complications occurred 64 times in relation to 55 patients with a higher incidence in allografts (61%) than in native kidneys (31%). Renal transplant patients showed higher serum creatinine values (5.8 +/- 0.8 vs. 3.2 +/- 0.4; p > 0.0001) and lower hematocrit (31.3 +/- 1.1 vs. 34.4 +/- 0.9; p = 0.025) than the native-kidney patients at the time of biopsy. De novo hematuria occurred in 30% of the procedures. In transplant patients, the gross hematuria incidence (9.9%) more than doubled that showed by native-kidney patients. The incidence of serious complications (hematoma, hemoperitoneum and AV fistula) was 16.5% and these were more frequent in transplant than in native kidneys.(ABSTRACT TRUNCATED AT 250 WORDS)