Setting Of Kidney Research Articles

THE DANGER OF DIGOXIN: TOXICITY WITHIN THE "THERAPEUTIC” RANGE

THE DANGER OF DIGOXIN: TOXICITY WITHIN THE "THERAPEUTIC” RANGE

Periodontitis and early mortality among adults treated with hemodialysis: a multinational propensity-matched cohort study

BackgroundPeriodontitis is associated with cardiovascular mortality in the general population and adults with chronic diseases. However, it is unclear whether periodontitis predicts survival in the setting of kidney failure.MethodsORAL-D was a propensity matched analysis in 3338 dentate adults with end-stage kidney disease treated in a hemodialysis network in Europe and South America designed to examine the association between periodontitis and all-cause and cardiovascular-related mortality in people on long-term hemodialysis. Participants were matched 1:1 on their propensity score for moderate to severe periodontitis assessed using the World Health Organization Community Periodontal Index.A random-effects Cox proportional hazards model was fitted with shared frailty to account for clustering of mortality risk within countries.ResultsAmong the 3338 dentate participants, 1355 (40.6%) had moderate to severe periodontitis at baseline. After using propensity score methods to generate a matched cohort of participants with periodontitis similar to those with none or mild periodontal disease, moderate to severe periodontitis was associated with a lower risk of all-cause (9.1 versus 13.0 per 100 person years, hazard ratio 0.74, 95% confidence interval 0.61 to 0.90) and cardiovascular (4.3 versus 6.9 per 100 person years, hazard ratio 0.67, 0.51 to 0.88) mortality. These associations were not changed substantially when participants were limited to those with 12 or more natural teeth and when accounting for competing causes of cardiovascular death.ConclusionIn contrast to the general population, periodontitis does not appear to be associated with an increased risk of early death in adults treated with hemodialysis.

Preserved Oxygenation Despite Reduced Blood Flow in Poststenotic Kidneys in Human Atherosclerotic Renal Artery Stenosis

Atherosclerotic renal artery stenosis reduces blood flow and perfusion pressures to the poststenotic kidney producing renovascular hypertension and threatening glomerular filtration rate. Little is known regarding regional tissue oxygenation in human renovascular disease that develops slowly. We compared stenotic and contralateral kidneys regarding volume, tissue perfusion, blood flow measured by multidetector computed tomography, and blood oxygen level-dependent magnetic resonance values in the cortex and medulla in 14 patients with unilateral stenosis (mean: 71% by quantitative computed tomography) and in 14 essential hypertensive patients during 150 mEq/d of sodium intake and renin-angiotensin blockade. Stenotic kidney volume was reduced compared with the contralateral kidney (118.6+/-9.9 versus 155.4+/-13.7 mL; P<0.01), as was total blood flow (269.7+/-42.2 versus 383.7+/-49; P=0.02), mainly because of reduced cortical volume. Tissue perfusion was similar but lower than essential hypertension (1.5 versus 1.2 mL/min per milliliter; P<0.05). Blood oxygen level-dependent MR at 3 T confirmed elevated R2* values (a measure of deoxyhemoglobin) in deep medullary regions in all 3 sets of kidneys (38.9+/-0.7 versus cortex 17.8+/-0.36 s(-1); P<0.0001). Despite reduced blood flow, R2* values did not differ between atherosclerotic and essential hypertensive kidneys, although furosemide-suppressible fall in medullary R2* was reduced in stenotic kidneys (5.7+/-1.8 versus 9.4+/-1.9 s(-1); P<0.05). Renal venous oxygen levels from the stenotic kidney were higher than those from essential hypertensives (65.1+/-2.2 versus 58.1+/-1.2; P=0.006). These data indicate that, although stenosis reduced blood flow and volume, cortical and medullary oxygenation was preserved under these conditions.

Hepatitis C in the setting of kidney, heart, lung, and bone marrow transplants

Hepatitis C virus (HCV) infection is a worldwide epidemic that is causing substantial morbidity and mortality in the general population. Due to inherent risks of HCV transmission through blood and tissue, solid organ and bone marrow transplant recipients have a higher incidence of HCV infection than that of the general population, especially in those transplanted prior to widespread screening for HCV in the early 1990s. The impact of HCV infection in liver transplantation is well characterized, but is less frequently discussed in kidney, heart, lung, and bone marrow transplantation. This article provides a comprehensive and current review of the literature with regard to the epidemiology, pathogenesis, outcome, and treatment of HCV infection in the setting of kidney, heart, lung, and bone marrow transplantation.

The Erythropoietin Gene Is Expressed Strongly in the Mammalian Mesonephric Kidney

In the ovine fetus at 41 days of gestation (term is 150 days), there are two sets of kidneys, mesonephrol and metanephrol. We have examined the expression of the erythropoietin (Epo) gene in both types of kidneys by competitive reverse transcriptase-polymerase chain reaction and hybridization histochemistry and compared the expression to that of the 60-day fetal metanephros. At 41 days, the Epo gene was expressed in both mesonephros and metanephros, as well as in the fetal liver. The cells expressing the Epo gene in the mesonephros were interstitial cells in the vicinity of the proximal tubules.

Why ontogeny recapitulates phylogeny.

In development, mammalian embryos successively develop notochord, somites, gill pouches and three sets of kidneys: pronephros, mesonephros and metanephros. Hence, Ernst Haeckel's dictum "ontogeny recapitulates phylogeny." The reason for this dictum appears to be the immortality of genes. Genes, once well entrenched, appear to linger for a long time even after the forfeiture of their raison d'être. The genes for dental enamel and dentin of the chicken are good examples. Furthermore, genes once doomed may resurrect themselves. For example, genes for red and green opsins of higher primates arose as alleles of the once doomed but resurrected red opsin locus.

Ultrapure polymerized bovine hemoglobin improves structural and functional integrity of the isolated perfused rat kidney.

Since it became evident that organ dysfunctions after acute hemolysis are not induced by hemoglobin per se, but by stroma-contaminated hemoglobin, solutions of ultrapure stroma-free hemoglobins were regarded to be possible substitutes for blood in transfusion medicine. We tested one of the recently developed modified bovine hemoglobins (Ultrapure polymerized bovine hemoglobin 1; UPPBHb1) in the isolated perfused rat kidney (IPRK) model, using a recirculating system. Control kidneys were perfused with a substrate-enriched Ringer solution containing hydroxyethyl starch (HES) to produce isoncotic conditions. In the experimental group HES was substituted in part by UPPBHb1 (34 g/l). For determination of functional parameters, the kidneys were perfused for 180 min. A separate set of kidneys of both groups was perfusion fixed after 80 min of perfusion which is the period of optimal function. Light and electron microscopic analysis revealed major alterations only for the outer medulla of HES kidneys. Only these suffered from a considerable extent of proximal tubular S3 damage, exhibiting condensed tubular epithelia. In the inner stripe of the outer medulla, which is the zone of greatest sensitivity to damage in the isolated perfused kidney, severe hydropic degeneration, cell detachment, and necrotic destruction of the medullary thick ascending limb were seen in the HES-perfused group, too. In the UPPBHb1 group, the medullary thick ascending limb was well preserved, and S3 showed only a minor degree of damage. UPPBHB1 kidneys were further characterized by the occurrence of intracapillary and interstitial precipitates of UPPBHb1 in inner stripe of the outer medulla and inner medulla. The glomerular filtration rate was significantly higher in UPPBHb1-perfused kidneys (870 +/- 80 vs. 630 +/- 55 microliters/min/g kidney weight for HES). Absolute reabsorption of sodium paralleled the behavior of the glomerular filtration rate. The values for renal perfusate flow and urinary flow rate did not differ significantly between both groups. Renal autoregulation was better preserved in UPPBHb1-perfused kidneys (74 +/- 6% of full autoregulatory response) than in HES-perfused controls (42 +/- 4%). Our results suggest that perfusion of isolated rat kidneys with UPPBHb1 improves kidney function and morphology, providing better oxygenation than in control kidneys. UPPBHb1 does not exert additional nephrotoxic effects on the IPRK that will exceed the noxious potential of the method itself. Thus, it must be concluded that UPPBHb1 may be an oxyphoretic blood substitute with nephroprotective characteristics when compared with nonoxyphoretic substitutes. At least, UPPBHb1 seems to be a promising candidate as oxyphoretic additive to perfusates for the IPRK model.

Transplantation of microbially contaminated cadaver kidneys.

Bacterial cultures of graft perfusion fluid were taken on 514 renal perfusions during a ten-year period. A total of 22 positive cultures were found. Two sets of kidneys were discarded because of the bacteriology report. Only two possible wound infections were found that could be attributable to the preoperative contamination even though 19 of 24 patients with "contaminated" kidneys received no antibiotics. No loss of kidneys or life was found. Of the 22 contaminated perfusates, 18 (80%) originated from other institutions although only 144 (28%) of the total kidneys that were perfused came from other institutions. The majority of cultures indicated that the organisms were skin contaminants or organisms of low virulence. Microbial contamination of perfused cadaver kidneys is uncommon (1.2% in local kidneys and 9.3% in shared kidneys). Contaminated kidneys are not a major source of infection in renal transplant recipients. Kidneys that are contaminated with frequently virulent Gram-negative bacteria, such as Escherichia coli, should be discarded. Contamination of kidneys with Gram-positive organisms should not be a contraindication for transplantation, but the patients should probably be given prophylactic antibiotics.