Stiff-person syndrome associated with cerebellar ataxia and high glutamic acid decarboxylase antibody titer

Glutamic acid decarboxylase (GAD) is the main target of humoral autoimmunity in patients with insulin-dependent diabetes mellitus (IDDM) and stiff-person syndrome. We reviewed the case of a 46-year-old woman who had cerebellar ataxia before getting stiff-person syndrome and IDDM with high anti-GAD autoantibody titers. This was a rare case in which there were both the clinical symptoms of stiff-person syndrome and cerebellar ataxia. In western blot analysis her serum reacted with 65-kDa proteins from rat cerebellum, cerebral cortex, and spinal cord. Autoantibodies to GAD may cause functional impairment of gamma-aminobutyric acid (GABA) neurons in the spinal cord as well as in the cerebellum.

Complication of oliguric acute renal failure in patients treated with low-molecular weight dextran

Acute renal failure (ARF) is a well-documented but infrequent complication in patients treated with low-molecular weight dextran (LMWD). We herein report 3 cases of oliguric ARF following the administration of dextran-40. One case developed ARF totally after 1.200 g of LMWD administration. In contrast, two cases having increased serum creatinine developed oliguria despite the acceptable therapeutic doses (totally 450 and 650 g). Contrast media was also co-administered in these patients. Plasma exchange (PE), double filtration plasmapheresis (DFPP), or continuous hemodiafiltration (CHDF) but not hemodialysis (HD) reduced circulating dextran concentrations by 35-44% during a single session. All patients completely recovered from ARF by 14-32 days after the treatment. Our cases suggested that radiocontrast could predispose to the development of LMWD-induced ARF especially in patients having pre-existing renal dysfunction. In addition, PE, DFPP and CHDF afforded a beneficial effect for removing accumulated LMWD from the circulation.

Effect of weekly or successive iron supplementation on erythropoietin doses in patients receiving hemodialysis

AIMS

To conduct a 3-month prospective study to determine the optimal way for intravenous iron supplementation in hemodialysis (HD) patients with resistance to recombinant human erythropoietin (rHuEPO) therapy due to deficient iron storage.

METHODS

Thirty-five HD patients with iron deficiency were divided into three groups: (1) patients receiving an intravenous infusion of 40 mg of iron during the first ten HD sessions (n = 12); (2) patients receiving 40 mg of iron injected once a week for 10 weeks (n = 12), and (3) patients without any iron supplementation (n = 11). The rHuEPO dosage was adjusted to maintain hemoglobin levels >10.0 g/dl, and the degree of anemia was assessed 3 months later.

RESULTS

In group 1, the hemoglobin levels were significantly increased after 4 weeks and remained increased until the end of the study (p < 0.01). In group 2, the hemoglobin levels were gradually increased until the end of the study (p < 0.01). There was no difference in the final hemoglobin values between both groups. The rHuEPO dosage was significantly decreased from 131 +/- 18 to 90 +/- 17 U/kg/week in group 1 (p < 0.01), but could not be changed in group 2 during the observation period despite a similar elevation of the serum ferritin level. In group 3, the rHuEPO doses were rather increased at the end of the study (p < 0.05).

CONCLUSION

Aggressive iron supplementation for the short term may be effective to restore rHuEPO hyporesponsiveness in HD patients with functional iron deficiency.

Amelioration of post-ischaemic renal injury by contralateral uninephrectomy: a role of endothelin-1

BACKGROUND

Previous studies showed that unilateral renal damage is attenuated by prior contralateral uninephrectomy (Nx) in ischaemia-induced acute renal failure (ARF). Since renal ischaemia increases endothelin-1 (ET-1) production in the kidney, we examined whether the alteration of renal ET-1 content may contribute to the nephrectomy-induced attenuation of renal injury.

METHODS

Ischaemic renal injury was provoked by 60-min left renal artery occlusion (RAO). Removal of the right kidney was performed just before RAO in the Nx group. Forty-eight hours after release of the clamp, renal ET-1 content was measured in both non-nephrectomized and unilaterally nephrectomized rats. We also examined the effects of a selective ET(A) receptor (FR139317) and monoclonal ET antibody (AwETN40) on the RAO-induced changes in renal haemodynamics at 2 and 48 h after RAO respectively.

RESULTS

The plasma concentration of ET-1 did not change in the two groups of ARF rats, but the cortical content of ET-1 increased to a lesser extent in Nx animals after ischaemia. Prior removal of the right kidney significantly facilitated the percentage recovery of left renal blood flow (RBF) during the first 2 h after release of the clamp. The percentage recovery of inulin clearance (Cin) by the kidney was also significantly better in Nx than sham-Nx rats at 48 h after RAO. Continuous administration of FR139317 (50 mg/kg/day) using osmotic minipumps for 3 days significantly attenuated exogenous ET-1-induced decrease in Cin and RBF. Infusion of FR139317 restored the decrease in RBF to control values during first 2 h in sham-Nx rats. However, FR139317 and AwETN40 did not ameliorate the RAO-induced decline of Cin in sham-Nx or Nx rats at 2 and 48 h after ischaemia respectively.

CONCLUSIONS

Contralateral uninephrectomy prior to ischaemia-induced ARF attenuated the increase in cortical ET-1 content and subsequent renal response to ischaemic injury. This beneficial effect of unilateral nephrectomy, however, was not mediated through well-preserved RBF due to reduced intrarenal ET-1 action.

Decreased plasma and cerebrospinal fluid glutamine concentrations in a patient with bialaphos poisoning

A 47-year-old Japanese woman undergoing maintenance hemodialysis (HD) was admitted to our hospital because of poisoning with the herbicide bialaphos. Respiratory arrest and loss of consciousness ensued rapidly, accompanied by convulsions and nystagmus. Treatment with HD and direct hemoperfusion, followed by HD alone, effectively removed bialaphos and its chief toxic metabolite (L-AMPB) from the circulation (bialaphos decreased from 0.33 to < 0.05 microg/ml and L-AMPB from 14 to 0.86 microg/ml). The glutamate concentration improved gradually after the removal of bialaphos and L-AMPB from plasma (plasma glutamate concentration: 250.4 nmol/l on day 5 to 120.6 nmol/l on day 26). Decreased glutamine concentration in cerebrospinal fluid was demonstrated for the first time as well as in plasma, indicating glutamine synthetase inhibition not only in plants but also in humans by bialaphos poisoning.

Hypercalcemia in a patient with B-cell acute lymphoblastic leukemia: a role of proinflammatory cytokine

The complication of hypercalcemia is reported to occur only in 2.5-4.8% of patients with acute lymphoblastic leukemia (ALL). We herein report a 53-year-old female patient with early B-cell ALL, complicated with extreme hypercalcemia (15.2 mg/dL). Bone X-ray revealed osteolytic changes in many locations. Serum 1,25(OH)2vitaminD3 and parathyroid hormone (PTH) levels were suppressed below normal ranges on admission. The circulating parathyroid hormone-related protein (PTHrP) value was within a normal range (< 1.1 pmol/L). Serum concentrations of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and soluble IL-2 receptor were increased to 72 pg/ml, 25.3 pg/ml, and 1469 U/ml, respectively. Following the induction chemotherapy, the serum calcium level was promptly normalized accompanied with decreases in serum TNF-alpha, IL-6 and soluble IL-2 receptor values to 34 pg/ml, 6.35 pg/ml, and 737 U/ml, respectively. Serum PTHrP values remained within detectable levels. To our knowledge, this is the first case of B-cell ALL in a patient who developed hypercalcemia with elevated concentrations of TNF-alpha, IL-6, and soluble IL-2 receptor, but not related to PTHrP. High circulating proinflammatory cytokines may have contributed to development of ALL-induced osteolysis and hypercalcemia in the present case.

Progressive renal failure and blindness due to retinal hemorrhage after interferon therapy for hepatitis C virus-associated membranoproliferative glomerulonephritis

We treated a 67-year-old Japanese woman with membranoproliferative glomerulonephritis (MPGN) and chronic active hepatitis associated with hepatitis C virus (HCV) infection. Treatment commenced with a daily dose of 6 MU IFN alpha-2b for 2 weeks, which was changed to three times weekly thereafter. After 2 weeks, HCV RNA in the serum was undetectable and there was a concomitant reduction in proteinuria. Treatment with IFN alpha-2b was discontinued because of severe headache and fever. Five weeks after the discontinuation of IFN alpha-2b, the patient experienced the sudden onset of visual loss due to retinal hemorrhage. Subsequently, proteinuria and renal function progressively deteriorated though HCV RNA was undetectable. This case exemplifies the need for careful monitoring of renal function and retinal lesions not only in patients receiving IFN but also in those following the discontinuation of IFN treatment.

Potential therapeutic effect of simvastatin on progressive renal failure and nephrotic-range proteinuria caused by renal cholesterol embolism

We report our experience with a 62-year-old Japanese man with cholesterol crystal embolism after angiographic procedures performed because of intermittent claudication. In addition to progressive renal failure and nephrotic-range proteinuria, cutaneous ischemia, consisting of livedo reticularis in the lower limbs and digital necrosis at the tip of the right toe, and fundoscopic findings showing several white spots in the branches of retinal artery were also observed. Progressive renal failure and nephrotic-range proteinuria were halted just after treatment with simvastatin. Thus, simvastatin can exert a beneficial therapeutic effect on renal cholesterol embolism.

Cytokines and cell cycle regulation in the fibrous progression of crescent formation in antiglomerular basement membrane nephritis of WKY rats

Cytokines may regulate cell proliferation by cell-cycle-regulatory proteins, in which cyclin-dependent kinase inhibitors (CDKI) inhibit cell proliferation. We investigated whether CDKI p21 or p27, both of which are potentially regulated by transforming growth factor (TGF)-beta, a key cytokine in fibrogenesis, are involved together with TGF-beta and/or platelet-derived growth factor (PDGF) in the fibrous progression of glomerular crescent formation and examined the sequential change in the cell type and the cellular background of myofibroblasts in crescent formation. Crescentic glomerulonephritis (GN) was induced by i.v. injection of rabbit antirat glomerular basement membrane antiserum in WKY rats. Animals were killed 1, 2, 3 and 4 weeks after the induction of GN, and their kidneys were processed for immunohistochemical examination. After 1 week more than 85% of glomeruli showed cellular crescents, which became fibrocellular with decreased cellularity by 4 weeks. ED 1-positive macrophages were components of crescent cells in about 44% at 1-2 weeks, and this proportion declined markedly afterwards. Alpha smooth muscle actin (alpha SMA, a marker for myofibroblasts)-positive cells were found in Bowman's epithelial cells (BEP) and in some crescent cells at 1 week, becoming major components of crescent cells by 4 weeks (about 40%). It was 2 weeks before invasion of alpha SMA-positive interstitial cells into glomeruli was evident. PDGF-B and PDGF receptor beta-positive cells, indicating possible targets for PDGF, were found in BEP adjoining crescent formation almost exclusively from 1 to 2 weeks. By contrast, both TGF-beta receptor types I- and II-positive cells, indicating possible effectors for TGF-beta, were found in BEP and crescent formation, and the percentage of these in the crescent formation did not change until 4 weeks (about 32%). Cells with positive immunostaining for proliferating cell nuclear antigen and cyclin A, markers for cell proliferation, in the crescent formation peaked in number and proportion at 1-2 weeks, then decreased. In contrast, cells with positive immunostaining for p21 and p27, CDKI, were sparse at 1 week, and then increased markedly in number and in proportion, peaking at 3 (39.6%) or 2-3 weeks (about 25-30%), respectively. The present study demonstrates that restrained expression or a transient increase in p21 and p27 may be associated with proliferation or with inhibited proliferation of crescent cells, most of which are macrophages and myofibroblasts. The action, of PDGF and TGF-beta may contribute to the recruitment of myofibroblasts into the crescent. The action of TGF-beta on crescent cells might be linked to the expression of p21 and/or p27.

Polymethylmethacrylate efficacy in reduction of renal itching in hemodialysis patients: crossover study and role of tumor necrosis factor-alpha

Pruritus is one of the major unsolved problems for patients receiving regular hemodialysis. In this study, we conducted a 6 month prospective and crossover trial to investigate the effect of polymethylmethacrylate (PMMA) membrane for renal itching. We also examined the role of the tumor necrosis factor (TNF)-alpha system for pruritus in hemodialysis patients. We assessed the degree of skin itching and measured circulating levels of TNF-alpha and soluble TNF receptors (sTNFR-I, sTNFR-II) in 19 patients using hemodialysis, complicated by prolonged severe pruritus for 6 months. Serum sTNFR-I and II levels were significantly elevated in hemodialysis patients compared to normal subjects. Serum sTNFR-II levels were significantly and negatively correlated with serum albumin (r = -0.602, p = 0.007). A significant positive relationship was also found between sTNFR-I and erythropoietin dosage (r = 0.554, p = 0.016). However, no association was found between the degree of pruritus and circulating sTNFR-I and II values. Skin itching scale was significantly decreased from 2.7 +/- 0.2 to 2.1 +/- 0.3 following the use of PMMA membrane for 3 months (p < 0.05). In contrast, there was no change in itching scales during 3 months of conventional therapy (2.2 +/- 0.3 versus 2.2 +/- 0.3, p = NS). PMMA itself did not affect serum TNF-alpha and sTNFR values as well as conventional dialyzer membranes. These findings suggested that the PMMA dialyzer can improve renal itching not mediated through the modification of the TNF-alpha system.

A case with acute renal failure complicated by Waldenström's macroglobulinemia and cryoglobulinemia

We encountered a 53-year-old man associated with acute renal failure caused by Waldenström's macroglobulinemia and type I cryoglobulinemia. Treatment with prednisolone and cyclophosphamide induced a rapid recovery from acute renal failure. Renal histology revealed endocapillary proliferation and lobular formation with scattered subendothelial, amorphous and periodic acid-Schiff (PAS)-positive materials in the glomerular capillaries which were positive for IgM on immunofluorescence study. Although the exact mechanism for pathophysiology of acute renal failure remains unknown, treatment with prednisolone and cyclophosphamide could induce a rapid recovery from acute renal failure accompanied by Waldenström's macroglobulinemia and type I cryoglobulinemia.

Tryptophan glycoconjugate as a novel marker of renal function

PURPOSE

Neither serum creatinine concentration nor creatinine clearance assess renal function accurately. Serum creatinine concentration is affected by muscle mass, and the creatinine clearance overestimates the glomerular filtration rate because of tubular secretion of creatinine. The present study was designed to determine whether serum concentrations of 2-(alpha-mannopyranosyl)-L-tryptophan (MPT), a tryptophan glycoconjugate, can be used as a marker of renal function.

METHODS

Clearances of MPT and of inulin were compared in normal rats and in rats with cisplatin-induced acute renal failure. We also compared the clearances of MPT and of creatinine with inulin clearance in 25 patients with chronic renal disease. Serum concentrations of MPT and creatinine as a function of MPT clearance were determined in 108 patients with chronic renal disease.

RESULTS

There was strong linear correlation between clearances of MPT and inulin in rats (r = 0.97) and humans (r = 0.87), indicating that renal handling of MPT is similar to that of inulin. In humans, linear regression analyses indicated that MPT was a better indicator of inulin clearance than was creatinine clearance. At the same level of renal function, serum creatinine concentrations tended to be lower in patients with less muscle mass (as indicated by a urinary creatinine excretion <1,000 mg in 24 hours) than in those who excreted >1,000 mg in 24 hours, whereas serum MPT concentrations were not affected by creatinine excretion.

CONCLUSION

MPT clearance can replace inulin clearance in the clinical setting. The serum MPT concentration is an accurate measure of renal function even in patients with diminished muscle mass, and thus is a better indicator of renal function than is the serum creatinine concentration.

Sequence of events in the glomerular capillary wall at the onset of proteinuria in passive Heymann nephritis

Proteinuria in passive Heymann nephritis (PHN) results from complement-mediated glomerular injury, since complement depletion with cobra venom factor (CVF) prevents proteinuria. However, there are no comprehensive morphological studies identifying the sites of injury leading to onset of proteinuria. To address this issue, we attempted to locate sites of injury involved in the onset of proteinuria in PHN. PHN was induced in intact Munich-Wistar rats (PHN-rats, examined at days 3, 5, and 7) and in complement-depleted rats (CVF treated, PHN-CVF-rats, examined at days 3 and 5). The distribution of endogenous albumin in the glomerular basement membrane (GBM) was studied in in situ drip-fixed glomeruli using immunogold immunocytochemistry, and glomerular anionic sites were visualized by polyethyleneimine staining. In addition, the ultrastructural localization of an epitope recognized by a proteinuria-inducing monoclonal antibody (called 5-1-6) directed against the slit diaphragm was examined. Significant proteinuria was seen in intact PHN-rats, starting at day 5. The intensity of gold labeling for endogenous albumin was significantly increased at the outermost site of the GBM (GBM interfacing foot process and the filtration slit, designated area O) at day 3 in both PHN-rats and PHN-CVF-rats in comparison to untreated controls. At day 5, labeling for albumin in area O was decreased in PHN-rats, but not in PHN-CVF-rats, where it was then higher; in PHN-rats, some areas between epithelial cells and subepithelial deposits were almost free of albumin labeling at day 7. There was no evidence of epithelial cell detachment in any group at day 5, but on day 7 limited focal detachment was seen exclusively in PHN-rats. In proteinuric rats, amorphous material that stained for albumin could be seen in the urinary space, without any exocytosis of labeling by glomerular epithelial cells. A significant reduction of intensity of staining for anionic sites was seen in parallel in both groups, but only in the regions of the lamina rara externa adjacent to subepithelial deposits. This local loss of charge might contribute to enhanced permeability to albumin in both PHN- and PHN-CVF-rats. Changes in the appearance of the filtration slits and in the density and distribution of antigen recognised by monoclonal antibody 5-1-6 were similar in PHN- and PHN-CVF-rats at day 5. Complement depletion prevented neither the reduction in anionic sites of the GBM nor the changes in the slit diaphragm observed. These data suggest that albumin leakage between the epithelial cell and the GBM (area O) could occur in PHN-rats, perhaps as a result of epithelial foot-process changes. This may be the final link in the chain of events responsible for the onset of proteinuria in PHN.

Role of atrophic tubules in development of interstitial fibrosis in microembolism-induced renal failure in rat

We explored the origin and participation of atrophic tubules in the progression of interstitial fibrosis using a new microembolic rat model of chronic renal failure in which foci of atrophic tubules with cuff-like basement membrane thickening developed at 4 weeks. Atrophic tubules, immunoreactive for vimentin and platelet-derived growth factor, were surrounded by transformed interstitial cells expressing platelet-derived growth factor receptor beta and alpha-smooth muscle actin. Some tubules in the deep cortex and the outer stripe of the outer medulla had a mosaic appearance. Tall, intact proximal tubular cells with a brush border and positivity for Phaseolus vulgaris erythroagglutinin, adjoined typical atrophic tubule cells having no brush border and an immunostaining pattern characteristic for atrophic tubules. The transformed interstitial cells expressing alpha-smooth muscle actin were located near atrophic but not intact tubular epithelial cells. Type IV collagen accumulated between damaged tubular cells and transformed interstitial cells. Heat shock protein 47 showed immunoreactivity in damaged epithelial cells and in interstitial myofibroblasts. Staining with an anti-endothelial antibody suggested damage to peritubular capillaries near atrophic tubules. By disturbance of microcirculation following microsphere injection, proximal tubular cells expressed vimentin and platelet-derived growth factor; diffusion of the latter presumably stimulated transformation of interstitial cells to myofibroblasts. Injured tubular epithelial cells and interstitial myofibroblasts both were responsible for interstitial fibrosis.

Defective electron transfer in complexes I and IV in patients with aceruloplasminemia

Aceruloplasminemia is a disorder of iron metabolism caused by mutations in the ceruloplasmin gene. It is characterized by progressive neurodegeneration of the retina, basal ganglia, dentate nucleus and cerebral cortex in association with iron accumulation in these tissues. Enzyme activities in the mitochondrial respiratory chain of the cerebral cortices of two patients were reduced to 62% and 71% for complexes I and IV. Malondialdehyde, a marker of lipid peroxidation, was three times higher than the control value and was accompanied by increased expression of superoxide dismutase 2 (Mn SOD). These findings suggest that iron-mediated free radicals contribute to the impairment of mitochondrial energy metabolism in aceruloplasminemia

New insights on the pathogenesis of hypercalcemia in primary hyperparathyroidism

The pathogenesis of hypercalcemia in primary hyperparathyroidism is attributed to increased calcium release from bone, increased calcium reabsorption in renal distal tubules, and increased intestinal calcium absorption. However, it remains unclear which factor is the main process. We encountered a 56-year-old woman with myasthenia gravis, in whom hypercalcemia and elevated serum parathyroid hormone (PTH) level were observed. Diagnosis of primary hyperparathyroidism was made. Treatment with methylprednisolone for myasthenia gravis was associated with a marked decrease in both biochemical markers of bone formation and resorption without any changes in endogenous cAMP and serum levels of calcium, PTH, and 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]. These findings suggest that the possible pathogenesis of hypercalcemia in primary hyperparathyroidism may be attributed to the increased calcium reabsorption in the kidney and the increased intestinal calcium absorption as a result of stimulated production of 1,25-(OH)2D3 in the kidney. It thus follows that the renal tubular effect rather than the skeletal effect of the PTH excess may play a pivotal role in the development of hypercalcemia in primary hyperparathyroidism.

Pruritus and hydration state of stratum corneum in hemodialysis patients

BACKGROUND

Xerosis is the most frequent cutaneous manifestation in hemodialysis (HD) patients, but the association between dry skin and pruritus remains to be clarified. Since the skin surface hygrometer can detect the changes of water content in the stratum corneum more sensitively, we re-examined the relationship between the severity of pruritus and water content in dialysis patients.

METHODS

Fifty patients who had been undergoing regular HD were examined for the degree of pruritus by clinical grading. Water contents in the stratum corneum at volar forearm and lower leg were assessed by measurement of high-frequency conductance using a skin surface hygrometer both at pre- and postdialysis.

RESULTS

Thirty-seven (74%) of dialysis patients complained of pruritus. High-frequency conductance values were significantly lower in HD patients compared to those of age-matched control subjects (n = 13) both at forearm (35.1+/-3.0 vs. 73.3+/-10.4 microS, p<0.01) and lower leg (14.2+/-1.1 vs. 52.4+/-7.5 microS, p<0.01). There was no relationship between the severity of pruritus and age, gender, HD duration, underlying renal disease, or removing fluid volume. A significant reduction of itching score was found in patients using polysulfone membrane. A single HD session using cellulose triacetate or polysulfone membrane significantly increased water content both at forearm and lower leg (p<0.05). However, the degree of pruritus did not correlate with the skin water content both at the beginning and the end of HD session, respectively.

CONCLUSION

It follows from these findings that water content in the stratum corneum was reduced in HD patients, but did not correlate with the severity of pruritus.

A patient with thrombotic microangiopathy accompanied by glomerular subendothelial electron dense deposits

A 50-year-old woman presented with thrombocytopenia, microangiopathic hemolytic anemia, and nephrotic syndrome. Although a high level of circulating immune complexes, mild hypocomplementemia, and the antinuclear antibody also were present, the criteria for collagen disease were not fulfilled. Renal biopsy demonstrated a typical thrombotic microangiopathy (TMA) involving glomeruli. There also were electron-dense deposits located just beneath the original glomerular basement membrane in the dilated subendothelial space, thought to be immune complexes following positive IgG, C1q and C3 staining on an immunofluorescent study. Corticosteroid therapy rapidly ameliorated her hematologic abnormalities and proteinuria and normalized the immunologic data. These findings strongly suggest that the TMA in this patient was induced by immune complex-associated mechanisms.

Possible involvement of myofibroblasts in cellular recovery of uranyl acetate-induced acute renal failure in rats

Cellular recovery in acute renal failure is a form of wound healing. Fibroblast-like cells or myofibroblasts are involved in wound healing. We examined the serial changes in tubular damage and origin and kinetics of regenerating cells in uranyl acetate-induced acute renal failure, with a special emphasis on interstitial myofibroblasts. Acute renal failure was induced in rats by intravenous injection of uranyl acetate (5 mg/kg). All rats received bromodeoxyuridine intraperitoneally 1 hour before sacrifice. Serial changes in the distribution of tubular necrosis and bromodeoxyuridine-incorporated or vimentin-positive regenerating cells, and their spatial and temporal relation to alpha-smooth muscle actin-positive myofibroblasts as well as ED 1-positive monocytes/macrophages were examined. Necrotic tubules initially appeared around the corticomedullary junction after uranyl acetate injection, then spread both downstream and upstream of proximal tubules. Peritubular alpha-smooth muscle actin-positive myofibroblasts appeared and extended along the denuded tubular basement membrane, establishing network formation throughout the cortex and the outer stripe of outer medulla at days 4 to 5. Tubular regeneration originated in nonlethally injured cells in the distal end of S3 segments, which was confirmed by lectin and immunohistochemical staining using markers for tubular segment. Subsequently, upstream proliferation was noted along the tubular basement membrane firmly attached by myofibroblasts. During cellular recovery, no entry of myofibroblasts into the tubular lumen across the tubular basement membrane was noted and only a few myofibroblasts showed bromodeoxyuridine positivity. The fractional area of alpha-smooth muscle actin-positive interstitium reached a peak level at day 7 in the cortex and outer stripe of outer medulla, then gradually disappeared by day 15 and remained only around dilated tubules and in the expanded interstitium at day 21. ED 1-positive monocytes/macrophages were transiently infiltrated mainly into the region of injury. They did not show specific association with initially necrotic tubules, but some of them located in close proximity to regenerating tubules. Nonlethally injured cells at the distal end of proximal tubules are likely to be the main source of tubular regeneration, and the transient appearance of interstitial myofibroblasts attached to the tubular basement membrane immediately after tubular necrosis might play a role in promoting cellular recovery in possible association with monocytes/macrophages in uranyl acetate-induced acute renal failure.

Impaired water excretion in a hyponatremic patient following thyroidectomy: causal role of glucocorticoid deficiency

We evaluated the causal role of glucocorticoid deficiency in the hyponatremia that developed in a 57-year-old Japanese man with hypothyroidism following the performance of a total thyroidectomy for laryngeal cancer. The plasma concentration of vasopressin (1.78 pg/ml) was not suppressed in the presence of hyponatremia (125 mEq/l). The urinary excretion of sodium was increased, and the plasma renin activity and plasma aldosterone concentration were suppressed. The infusion of hypertonic saline increased the plasma osmolality, but not the plasma concentration of vasopressin. An oral water load (20 ml/kg of body weight) did not suppress the plasma vasopressin level or induce diuresis. Pretreatment with hydrocortisone normalized the response of plasma vasopressin to the water load was well as the diuretic response during the hypothyroid state. The urinary excretion of 17-hydroxycorticosteroids was below normal in the hypothyroid state in the face of normal serum cortisol concentration. The correction of the hypothyroidism returned these abnormalities to normal. A disturbed metabolism of glucocorticoid may have been responsible for the hyponatremia and disturbance in plasma vasopressin regulation observed in this hypothyroid patient.