D-Lactic acidosis has been well documented in ruminants. In humans, D-lactic acidosis is very rare, but D-lactic acidosis may be more common than generally believed and should be looked for in a case of metabolic acidosis in which the cause of acidosis is not apparent. The clinical presentation of D-lactic acidosis is characterized by episodes of encephalopathy and metabolic acidosis. The entity should be considered as a diagnosis in a patient who presents with metabolic acidosis accompanied by high anion gap, normal lactate level, negative Acetest, history of short bowel syndrome or malabsorption, and characteristic neurologic manifestations. Low carbohydrate diet, bicarbonate treatment, rehydration, and oral antibiotics would be helpful in controlling symptoms.
Acid-Base Equilibrium ; Acidosis* ; Anti-Bacterial Agents ; Diagnosis ; Diet, Carbohydrate-Restricted ; Fluid Therapy ; Humans* ; Lactic Acid ; Neurologic Manifestations ; Ruminants ; Short Bowel Syndrome

In end-stage renal disease (ESRD) patients regardless of dialysis modes, i.e. maintenance hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD), potassium (K) homeostasis is regulated primarily via dialysis and extrarenal K regulation in the diverse daily K intake. However, K metabolism has been known to differ greatly between the two main methods of dialysis. Hyperkalemia is a common complication (10-24%) and the most common cause of the death (3-5%) among electrolyte disorders in patients on maintenance HD. On the contrary, hypokalemia (10-36%) is responsible for a rather common complication and independent prognostic factor on CAPD. Although excessive K intake or inadequate dialysis on maintenance HD and poor nutritional K intake on CAPD are accused without doubts upto 50% of ESRD patients as a primary cause of the K-imbalance, i.e. hyperkalemia on HD and hypokalemia on CAPD, other contributory factors including certain medications and unknown causes remain still to be resolved. Accordingly, the effects of medications as another source of K-imbalance on HD with RAS blockades and beta blockers as well as those of conventional and glucose-free dialysates (Icodextrin) for internal K-redistribution on CAPD were evaluated with reviewing the literatures and our data. Furthermore, new developments in the clinical managements of hyperkalemia on HD following the exclusion of pseudohyperkalemia before the initiation of dialysis were suggested, especially, by the comparison of the effects between mono- and dual-therapy with medications for transcellular K shifting in the emergent situation. Also, the intraperitoneal K administration via conventional glucose-containing (2.5%) and glucose-free dialysates (Icodextrin) as a specific route of K-supplementation for hypokalemia on CAPD was examined for its efficiency and the degree of intracellular K shift between these two different types of dialysates.
Dialysis ; Dialysis Solutions ; Homeostasis ; Humans ; Hyperkalemia ; Hypokalemia ; Kidney Failure, Chronic ; Metabolism ; Peritoneal Dialysis, Continuous Ambulatory* ; Potassium ; Renal Dialysis*

The anion gap in the serum is useful in the interpretation of acid-base disorders and in the diagnosis of other conditions. In the early 1980s, ion-selective electrodes for specific ionic species were introduced for the measurement of serum electrolytes. This new method has caused a shift of the anion gap from 12+/-4 mEq/L down 6+/-3 mEq/L. It is worthy for clinicians to understand the range of normal anion gap and the measuring methods for serum sodium and chloride in the laboratories that support their practice. While an increase in the anion gap is almost always caused by retained unmeasured anions, a decrease in the anion gap can be generated by multiple mechanisms.
Acid-Base Equilibrium* ; Anions ; Diagnosis ; Electrolytes ; Ion-Selective Electrodes ; Sodium

Tubulointerstitial (TI) fibrosis is a final common pathway to progressive renal injury of all forms of renal disease. However, once renal damage reaches a certain threshold, progression of renal disease is consistent, irreversible, and largely independent of the initial injury. Angiotensin (AT) II is the main effector of the renin angiotensin system (RAS) and effects that may contribute to the onset and progression of renal damage. AT II may also directly contribute to accelerate renal damage by sustaining cell growth, inflammation, and fibrosis. Interventions that inhibit the activity of the RAS are renoprotective and may retard or even halt the progression of chronic nephropathies. Unilateral ureteral obstruction suggested as a well-established experimental model of progressive interstitial expansion and fibrosis. Although technically challenging, some investigators have successfully relieved the obstruction and reported significant reduction in interstitial fibrosis severity. Drugs that modulate the RAS, such as ACE inhibitors and angiotensin type 1 (AT1) receptor antagonists, have demonstrated protective renal effects and can ameliorate fibrosis. However, neither ACE inhibitor nor AT1 receptor blockade completely suppresses progression of renal disease. Dual blockade of the RAS with ACE inhibitors and AT1 receptor blockers may provide renal benefit beyond therapy with either drug alone, due to their potential additive beneficial effect.
Angiotensin-Converting Enzyme Inhibitors ; Angiotensins* ; Fibrosis* ; Humans ; Inflammation ; Models, Theoretical ; Renin-Angiotensin System ; Research Personnel ; Ureteral Obstruction

Nephrotic syndrome and liver cirrhosis are common clinical manifestations, and are associated with avid sodium retention leading to the development of edema and ascites. However, the mechanism for the sodium retention is still incompletely understood and the molecular basis remains undefined. We examined the changes of sodium (co)transporters and epithelial sodium channels (ENaCs) in the kidneys of experimental nephrotic syndrome and liver cirrhosis. The results demonstrated that puromycin- or HgCl2?induced nephrotic syndrome was associated with 1) sodium retention, decreased urinary sodium excretion, development of ascites, and increased plasma aldosterone level; 2) increased apical targeting of ENaC subunits in connecting tubule and collecting duct segments; and 3) decreased protein abundance of type 2 11beta-hydroxysteroid dehydrogenase (11betaHSD2). Experimental liver cirrhosis was induced in rats by CCl4 treatment or common bile duct ligation. An increased apical targeting of alpha-, beta-, and gamma-ENaC subunits in connecting tubule, and cortical and medullary collecting duct segments in sodium retaining phase of liver cirhosis but not in escape phase of sodium retention. Immunolabeling intensity of 11betaHSD2 in the connecting tubule and cortical collecting duct was significantly reduced in sodium retaining phase of liver cirrhosis, and this was confirmed by immunoblotting. These observations therefore strongly support the view that the renal sodium retention associated with nephrotic syndrome and liver cirrhosis is caused by increased sodium reabsorption in the aldosterone sensitive distal nephron including the connecting tubule and collecting duct, and increased apical targeting of ENaC subunits plays a role in the development of sodium retention in nephrotic syndrome and liver cirrhosis.
11-beta-Hydroxysteroid Dehydrogenases ; Aldosterone ; Animals* ; Ascites ; Common Bile Duct ; Edema ; Epithelial Sodium Channels ; Immunoblotting ; Kidney ; Ligation ; Liver Cirrhosis* ; Liver Cirrhosis, Experimental ; Liver* ; Models, Animal* ; Nephrons ; Nephrotic Syndrome* ; Plasma ; Rats ; Sodium ; United Nations

To produce a concentrated urine, the renal medulla needs hypertonicity for the reabsorption of free water from collecting duct. The single effect that increases interstitial tonicity in the outer medulla is the active NaCl reabsorption in the thick ascending limb, while the single effect in the inner medulla is the passive efflux of NaCl through the thin ascending limb. The passive mechanism in the inner medulla requires high interstitial urea concentration. Two main groups of urea transporters (UT-A, UT-B) are present in the kidney, which maintains the high concentration of urea in the deepest portion of the inner medulla by intra-renal urea recycling. Recent studies suggest that UT-A1 in the terminal inner medullary collecting duct is up-regulated when urine or inner medullary interstitial urea is depleted in order to enhance the reabsorption of urea, while UT-A2 in the descending thin limb of loops of Henle and UT-B in the descending vasa recta are increased when outer medullary interstitial urea concentration is high, in order to prevent the loss of urea from the medulla to the systemic circulation, thereby increasing intra-renal urea recycling. This review will summarize the functions of the renal urea transporters in urine concentration mechanism and the recent knowledge about their long-term regulation.
Extremities ; Kidney ; Recycling ; Urea* ; Water

The kidney is an important organ for controlling the volume of body fluids, electrolytic balance and excretion/reabsorption of endogenous and exogenous compounds. Among these renal functions, excretion/reabsorption of endogenous and exogenous substance is very important for the maintenance of physiological homeostasis in the body. Recently discovered organic anion transporters (OAT or SLC22A) have important roles for renal functions. It is well known as drug transporter. Several isoforms belong to SLC22A family. They showed different transport substrate spectrums and different localizations within the kidney. Their gene expressions are changed by some stimulus. The functional transport properties are regulated by protein kinase C. In addition, the function of organic anion transporters are also regulated by protein-protein interaction, such as caveolin which is compositional protein of caveolae structure. In this review, we will give an introduction of organic anion transporters and its regulatory mechanisms.
Body Fluids ; Caveolae ; Caveolins* ; Gene Expression ; Homeostasis ; Humans ; Kidney ; Multidrug Resistance-Associated Proteins ; Organic Anion Transporters* ; Protein Isoforms ; Protein Kinase C ; Xenobiotics

Nitric oxide (NO) is synthesized within the adult and developing kidney and plays a critical role in the regulation of renal hemodynamics and tubule function. In the adult kidney, the regulation of NO synthesis is very cell type specific and subject to distinct control mechanisms of NO synthase (NOS) isoforms. Endothelial NOS (eNOS) is expressed in the endothelial cells of glomeruli, peritubular capillaries, and vascular bundles. Neuronal NOS (nNOS) is expressed in the tubular epithelial cells of the macula densa and inner medullary collecting duct. Furthermore, in the immature kidney, the expression of eNOS and nNOS shows unique patterns distinct from that is observed in the adult. This review will summarize the localization and presumable function of NOS isoforms in the adult and developing kidney.
Adult* ; Capillaries ; Endothelial Cells ; Epithelial Cells ; Hemodynamics ; Humans ; Kidney* ; Neurons ; Nitric Oxide Synthase ; Nitric Oxide* ; Protein Isoforms

Cyclophosphamide is clinically useful in treating malignancy and rheumatologic disease, but has limitations in that it induces hyponatremia. The mechanisms by which cyclophosphamide induces water retention in the kidney have yet to be identified. This study was undertaken to test the hypothesis that cyclophosphamide may produce water retention via the proximal nephron, where aquaporin-1 (AQP1) and aquaporin-7 (AQP7) water channels participate in water absorption. To test this hypothesis, we gave a single dose of intraperitoneal cyclophosphamide to male Sprague-Dawley rats and treated rabbit proximal tubule cells (PTCs) with 4-hydroperoxycyclophosphamide (4-HC), an active metabolite of cyclophosphamide. In the short-term 3-day rat study, AQP1 protein expression was significantly increased in the whole kidney homogenates by cyclophosphamide administration at 48 (614 +/- 194%, P < 0.005), and 96 (460 +/- 46%, P < 0.05) mg/kg BW compared with vehicle-treated controls. Plasma sodium concentration was significantly decreased (143 +/- 1 vs. 146 +/- 1 mEq/L, P < 0.05) by cyclophosphamide 100 mg/kg BW in the long-term 6-day rat study. When primary cultured rabbit PTCs were treated with 4-HC for 24 hours, the protein expressions of AQP1 and AQP7 were increased in a dose-dependent manner. Quantitative polymerase chain reaction revealed no significant changes in the mRNA levels of AQP1 and AQP7 from cyclophosphamide-treated rat renal cortices. From these preliminary data, we conclude that the proximal nephron may be involved in cyclophosphamide-induced water retention via AQP1 and AQP7 water channels. Further studies are required to demonstrate intracellular mechanisms that affect the expression of AQP proteins.
Absorption ; Animals ; Aquaporin 1 ; Aquaporins ; Cyclophosphamide ; Factor IX ; Humans ; Hyponatremia ; Kidney ; Male ; Nephrons ; Plasma ; Polymerase Chain Reaction ; Proteins ; Rats ; Rats, Sprague-Dawley ; Retention (Psychology) ; RNA, Messenger ; Sodium ; Water

Mineral metabolism abnormalities, such as low 1,25-dihydroxyvitamin D (1,25(OH)2D) and elevated parathyroid hormone (PTH), are common at even higher glomerular filtration rate than previously described. Levels of 25-hydroxyvitamin D (25(OH)D) show an inverse correlation with those of intact PTH and phosphorus. Studies of the general population found much higher all-cause and cardiovascular (CV) mortality for patients with lower levels of vitamin D; this finding suggests that low 25(OH)D level is a risk factor and predictive of CV events in patients without chronic kidney disease (CKD). 25(OH)D/1,25(OH)2D becomes deficient with progression of CKD. Additionally, studies of dialysis patients have found an association of vitamin D deficiency with increased mortality. Restoration of the physiology of vitamin D receptor activation should be essential therapy for CKD patients.
Dialysis ; Glomerular Filtration Rate ; Humans ; Kidney ; Kidney Diseases ; Parathyroid Hormone ; Phosphorus ; Receptors, Calcitriol ; Renal Insufficiency, Chronic ; Risk Factors ; Vitamin D ; Vitamin D Deficiency ; Vitamins