Down modulation of Heymann's nephritis by mercuric chloride

The time course of Heymann's nephritis (HN), assessed on proteinuria and immunomorphology, has been compared in Lewis (LEW) rats immunized with BB alone (group A) or injected with HgCl2 and subsequently immunized in a similar manner (group B). Whereas all rats from group A developed typical HN characterized by heavy proteinuria and abundant glomerular immune deposits, rats from group B did not develop or developed a markedly attenuated form of HN; proteinuria was never detectable, immune deposits were absent or minimal. No abnormalities were found in rats injected with HgCl2 alone. In order to explain our findings, we have studied the glomerular and tubular expression of the 330 kD nephritogenic glycoprotein (gp330) as well as the corresponding antibody response. In rats receiving HgCl2, gp330 was normally expressed on BB and glomerular epithelial cells as indicated by in vitro and in vivo binding of anti-gp330 antibodies, but titers of anti-BB and anti-gp330 antibodies were considerably lower than in group A control rats. These findings therefore suggest that HgCl2 acts by its immunodepressive effect recently related to an increase in T suppressor cells. This effect is paradoxical since HgCl2 induces autoimmunity in Brown-Norway rats, and we suggest that it may be akin to observations reported in clinical practice where drugs may be immunostimulatory in some patients and immunodepressive in others. The mercury model may therefore represent a unique tool to evaluate the relationship between genetics and drug-induced immune dysregulation.     

Modification of renal cortical subcellular membrane phospholipids induced by mercuric chloride

Administration of mercuric chloride (HgCl2, 6 mg/kg) to rabbits produced renal failure, with changes in serum creatinine from 1.01 +/- 1 in controls to 6.46 +/- 0.91 mg/dl 24 hr after administration. Mitochondria isolated from HgCl2-treated rabbits exhibited alterations in acceptor control ratios, with reduction to 1.9 +/- 0.2 from 3.9 +/- 1.2 in controls. Ultrastructurally, the mitochondria showed swelling and loss of inner mitochondrial membranes. Total lipids from mitochondria of control and treated rabbits were obtained by modified Folch extraction and phospholipids analyzed by TLC. Brush border membranes and basolateral membranes were prepared from control and HgCl2-treated kidneys 2 and 24 hr after HgC12 administration. At 24 hr mitochondria showed a 36% fall in phosphatidylcholine (PC), a 36% fall in phosphatidylethanolamine (PE), and a 27% fall in cardiolipin. Brush border showed a decrease in phosphatidylserine (PS) of 29% and in PE of 40%. The basolateral membranes showed a reduction only in PE of 35%. At 2 hr post HgCl2, early changes are confined to the BBM and consist of a reduction in PE in this membrane. This changes in membrane phospholipids may be important in the functional derangements that occur at the cellular level after HgCl2 administration.     

Inhibition of experimental nephrocalcinosis with a prostaglandin synthetase inhibitor

Nephrocalcinosis was induced in a group of experimental rats by means of intraperitoneal injections of 10% calcium gluconate. Two further groups of rats were treated with indomethacin and flurbiprofen (Froben) before receiving the i.p. calcium gluconate, to study the effects of prostaglandin inhibition on the process of renal parenchymal calcification. Tissue calcification was studied by means of contact microradiography and histology. Quantitative calcium analysis was by means of energy dispersive analysis of X-rays (EDAX). There was a marked inhibition of cortical nephrocalcinosis and a significantly reduced calcium concentration (P less than 0.005) in the animals treated with a prostaglandin inhibitor compared with the animals given i.p. calcium gluconate alone. This study suggests that prostaglandins are involved in the process of renal parenchymal calcification and may be aetiologically significant in the pathogenesis of stone formation.     

Effect of mercuric chloride on membrane—bound enzymes in rat testis

Aim: To study the effect of mercuric chloride on the membrane-bound enzymes. Methods: The effect of mercuric chloride at two different doses, 1 mg/kg (low dose) and 2 mg/kg (high dose), orally for 30 days, was observed on the membrane-bound enzymes in the testis of adult albino rats. Results: Mercuric chloride significantly decreased the body weight and testis weight in the high dose group (P<0.05), but not in the low dose group. The activities of 5' nucleotidase and adenosine triphosphatases were markedly decreased (P<0.01) in the testis of both groups. Alkaline phosphatase and γ-glutamyl transferase activities were significantly increased (P<0.01) in both groups. However, the effect was more pronounced in the high than in the low dose groups. Conclusion: The dose dependent effect of mercuric chloride on these enzymes may affect the membrane characteristics and thereby the fertility of the animal. (Asian J Androl 2002 Dec; 4:309-311)     

Lipid alterations in LLC-PK1 cells exposed to mercuric chloride

We have studied the effects of HgCl2 on the lipids of LLC-PK1 (pig kidney) epithelial cells. Our results show that treatment of cells with HgCl2 caused a rapid accumulation of unesterified fatty acids (particularly arachidonic acid) and lysophospholipids. A 27-fold increase in unesterified arachidonic acid and a 17-fold increase in lysophosphatidylethanolamine (LPE) was accompanied by a 26% decline in the mass of phosphatidylethanolamine as determined by gas chromatography and lipid phosphorus assay. Similar changes were seen following HgCl2 treatment of cells whose lipids were labelled with 14C stearic acid, 3H arachidonic acid, or 14C acetate, but the radiolabelling techniques also identified an increased content of label in lysophosphatidylcholine (LPC) and a corresponding decrease in phosphatidylcholine. These alterations were accompanied by the formation of blebs on the plasma membrane and irreversible injury as indicated by electron microscopy. The possible role of unesterified fatty acids in the pathogenesis of injury was studied by adding fatty acids to the cells. The addition of unsaturated fatty acids (oleic, linoleic, or arachidonic acids) to the cells caused plasma membrane blebbing and loss of viability. Similarly, the addition of LPC or LPE to the cells resulted in cell death; however, plasma membrane blebbing did not result.     

Murine aortic aneurysm produced by periarterial application of calcium chloride

A murine abdominal aortic aneurysm model was developed by applying calcium chloride periarterially. A 13.6 mEq/10 ml calcium chloride solution was applied to the abdominal aorta of nine mice. Three mice were randomly selected at the end of the first, second, and third weeks postoperatively, and their vessel diameters were measured. The vessel diameter at the end of the first week postoperatively was 0.39 +/- 0.03 mm (mean +/- SD) pretreatment and 0.41 +/- 0.03 mm posttreatment (5.3% increase, P > 0.05). The vessel diameter at the end of the second week postoperatively was 0.48 +/- 0.03 mm pretreatment and 0.78 +/- 0.20 mm posttreatment (64% increase, P < 0.05). The vessel diameter at the end of the third week postoperatively was 0.57 +/- 0.14 mm pretreatment and 1.16 +/- 0.43 mm posttreatment (110% increase, P < 0.05). Nine other murine abdominal aortas were treated with sodium chloride, and their vessel diameters were measured in similar 7-day intervals. No measurements in this group were statistically significant when comparing pretreatment to posttreatment vessel diameters. A larger number of inflammatory infiltrates was observed in the intima and media layers of calcium-chloride-treated mice. Underlying mechanisms for this model include disrupting the elastic network within the media by calcium precipitations and activating the inflammatory response. We conclude that periarterial application of calcium chloride is a convenient and reliable model for creating abdominal aortic aneurysms in mice.     

Time course of growth factor expression in mercuric chloride acute renal failure

BACKGROUND.: Renal EGF expression decreases in varying models of acute renalfailure (ARF). We found previously that the loss of distal tubularEGF during gentamicin ARF is strongest in the cortex, whereproximal tubular injury was most severe. To gain more insightinto the mechanism underlying this apparent anatomical association,renal growth factor expression was investigated during mercuricchloride ARF, in which proximal tubular injury is most severein the outer stripe of the outer medulla (OSOM). METHODS.: Endogenous renal growth factor expression was investigated byRNA hybridization and by imrnunohistochemistry in a rat modelof mercuric chloride ARF. In addition we determined temporaland spatial profiles of tubular injury, cell proliferation,and mononuclear cell infiltration during the 3-week observationperiod. RESULTS.: Serum creatinine values were maximal 2 days after treatmentand were again normalized at day 6. Tubular injury was mostsevere in the PST and maximal at day 2. Cell proliferation wasalso highest in the PST and maximal at day 4. Three weeks aftertreatment, normal renal morphology was restored. Increased numbersof mononuclear cells appeared transiently in the renal interstitiumfrom day 1 on. Most of these cells were macrophages and T lymphocytes;macrophages surrounded preferentially the severely injured PSTin the OSOM. In analogy to gentamicin ARF, renal EGF and IGF-Igene expression were decreased early in the setting of mercuricchloride ARF. The decrease in distal tubular EGF staining wasmost pronounced in the OSOM, i.e. the anatomical area wheremercuric-chloride-induced proximal tubular injury was most severe. CONCLUSIONS.: Renal EGF and IGF-I gene expression decreases strongly duringmercuric chloride ARF. The spatial association between the initialdecrease of distal tubular EGF expression and the zone of majorproximal tubular injury could originate from metabolic alterationssecondary to oxygen starvation. A possible role of mononuclearcells remains to be determined.     

Renal antigens in mercuric chloride induced, anti-GBM autoantibody glomerular disease.

Two antibody probes were used to characterize the putative renal antigens of HgCl2-induced antiglomerular basement membrane renal disease in Brown Norway (BN) rat. The first probe was the linear immunofluorescence imparting, in vivo bound, nephritogenic antiglomerular-basement-membrane autoantibody (anti-GBM-Ab). The second probe was a rat monoclonal antibody to the B subunit of laminin that was obtained from fusion of spleen cells of HgCl2 injected BN rat. By enzyme-linked immunosorbent assay (ELISA) the anti-GBM-Ab reacted with laminin, type IV collagen, collagenase-resistant noncollagenous portion of glomerular basement membrane (GBM), saline soluble proteins of kidney cortex homogenate and fibronectin. Western blot analysis of laminin indicated that the reactive epitopes detected by both probes were on the B chain subunit but not the A subunit. In nonreduced collagenase-digested GBM the epitopes were present on 27 kD and 42 to 48 kD polypeptides. A similar pattern was seen on collagenase-digested human GBM. On rat and human GBM the patterns obtained with rat autoantibody and autoantibody from a patient with Goodpasture syndrome were similar, suggesting that some of the in vivo bound anti-GBM autoantibodies in HgCl2-induced disease in rat are directed against epitopes which are similar to the Goodpasture antigen of human. Reactive epitopes were also detected on saline soluble proteins of kidney cortex homogenate with the predominant antigen being a 31 kD polypeptide. In the saline soluble proteins the reactive polypeptides including the major 31 kD polypeptide did not originate from laminin, type IV collagen, or the collagenase-resistant noncollagenous part of GBM. The precise structural origin of soluble proteins was not defined.(ABSTRACT TRUNCATED AT 250 WORDS)     

Nephroprotective potential of selenium and taurine against mercuric chloride induced nephropathy in rats

The study was aimed to estimate whether pre-treatment with sodium selenite or taurine would reverse kidney damage induced by intraperitoneal injection of mercuric chloride in rats. Animals were divided into six groups: (1) control group; (2) sodium selenite group; (3) taurine group; (4) HgCl₂ group; (5) sodium selenite pretreated group; (6) taurine pretreated group. The results demonstrated that HgCl₂ causes significant enhancement in serum malondialdehyde (MDA), creatinine, N-acetyl-beta-d-glucosaminidase (NAG), cystatin C, nephrin and interleukin 6 (IL-6) levels accompanied with significant reduction in serum nitric oxide (NO) level. Pretreatment with sodium selenite or taurine produces significant depletion in MDA, NAG, cystatin C, nephrin and IL-6 levels in concomitant with significant elevation in serum NO level as compared to HgCl₂ group. HgCl₂ induced pathological alterations in the kidney. The ultrastructural investigation of renal cortex of HgCl₂-administered group revealed that the glomerular basement membrane is uniform, the fenestrations of endothelial cells are swollen, and the secondary foot processes appear also swollen even fused at some points. The proximal convoluted tubules showed apical short and few microvilli, while, some tubular cells showed relatively normal microvilli. In contrast, sodium selenite or taurine pretreatment could significantly reduce the pathological alterations in the kidney caused by HgCl₂ intoxication. The current results suggested that selenium and taurine possess nephroprotective efficacy due to their antioxidative capacity and anti-inflammatory activity.     

Fluorescent imaging of acute mercuric chloride exposure on cultured human kidney tubular epithelial cells

BACKGROUND: Imaging of intracellular mercuric ion is necessary for mechanism of renal toxicity of exposure to HgCl2. The distribution of Hg2+ inside a living cell, however, is still invisible due to the lack of high selective and sensitive fluorescent molecular probe for Hg2+. METHODS: A new fluorescent probe, EPNP, was applied to the cultured cells of human kidney proximal tubular epithelial cell line (HKC) in the presence of HgCl2 and some other bivalent ions. The relative fluorescence intensity of EPNP was measured and fluorescence images were taken by laser scanning confocal microscope. RESULTS: Results showed it led to an Hg2+ concentration- and time-dependent increase in fluorescence intensity, and responded weakly for some other heavy and transition metal ions. It could be seen during acute exposure on HKC cells, Hg2+ locate perinuclear, and on nuclear membrane, which was beyond what one knew before. CONCLUSION: EPNP is a real-time and on-line probe for imaging Hg2+ in a living cell due to its high selectivity and sensitivity for Hg2+ and slow bleaching/fading. Both the probe and the new results about the distribution of intracellular Hg2+ may be helpful for relevant biologic research.     

Effects of furosemide on low-dose mercuric chloride acute renal failure in the rat.

The use of potent diuretics in acute renal failure remains controversial. Both beneficial and detrimental effects have been reported. In the present study, the effects of both low and high doses of furosemide administered in the developmental and established stages of mercuric chloride-induced acute renal failure were evaluated. Both low and high doses of furosemide produced a significant diuresis when given early in the course of experimental acute renal failure. Despite this diuresis, furosemide did not modify the development of the acute renal failure. Continued administration of a low dose of furosemide had no effect on renal function; however, prolonged administration of high doses of furosemide resulted in significantly lower creatinine clearances 48 hr after induction of acute renal failure. This detrimental effect was due to sodium depletion by the diuretic since it was prevented by continuous replacement of urinary sodium losses. In the absence of sodium depletion, high doses of furosemide produced a significant diuresis, both in the developmental and established phases of acute renal failure, but it had no effect on the degree of renal functional impairment.     

Endourologic treatment of nephrocalcinosis

Calcifications of the kidney may be located free within the collecting system, attached to a papilla, trapped beneath the urothelium, or sequestered in the renal parenchyma. Extracorporeal shock wave lithotripsy has failed to render patients who presented with nephrocalcinosis stone free because of the submucosal location of some of the calculi. We report a unique case of symptomatic nephrocalcinosis in which the patient was rendered stone free using flexible ureteroscopy and intrarenal laser and electrohydraulic lithotripsy to treat both the attached and submucosal papillary calculi.     

Continuous infusion of oxalate by minipumps induces calcium oxalate nephrocalcinosis

It is hypothesized that oxalate plays an active role in calcium oxalate (CaOx) nephrocalcinosis and oxalate driven nephrolithiasis by interacting with the kidney. We developed an adjustable, nonprecursor, continuous infusion model of hyperoxaluria and CaOx nephrocalcinosis to investigate this hypothesis. Minipumps containing PBS or KOx (60–360 μmol/day; n=5–7/dose) were implanted subcutaneously in male Sprague–Dawley rats on D0 and D6. Rats were killed on D13. Oxalate excretion and CaOx crystalluria were monitored by 20+4 h urine collections. Localization and content of intrarenal crystals were determined on frozen sections using polarization and μFTIR. Oxalate excretion was significantly elevated in all KOx rats (P≤0.005). CaOx crystalluria was most persistent in the 240–360 μmol/day KOx rats, but even 60 μmol/day KOx rats showed sporadic crystalluria. One hundred percent of KOx rats had CaOx nephrocalcinosis as confirmed by μFTIR. Most crystals were localized to the lumens of the corticomedullary collecting ducts. A few crystals are localized just under the papillar urothelium. The minipump model is the first model of hyperoxaluria to provide continuous infusion of oxalate. It permits control of the levels of hyperoxaluria, crystalluria and CaOx nephrocalcinosis. The level of sustained hyperoxaluria and CaOx nephrocalcinosis induced by treatment with 360 μmol/day KOx for 13D models the conditions frequently observed in jejunoileal bypass patients. Adjustments in the length of treatment and level of hyperoxaluria may allow this model to also be used to study the oxalate driven CaOx-nephrolithiasis common in patients with hyperoxaluria due to other causes.     

单基因肾钙质沉着症的研究进展

肾钙质沉着症常与肾结石病伴发,近年来越来越多的肾钙质沉着症被发现是由单基因病所致,其发病机制尚未完全阐明。随着分子遗传学的发展,已发现30多种基因是肾钙质沉着症的致病基因。同时,随着基因检测技术的广泛开展,更多的患者得到了早期诊断和及时干预。现就单基因肾钙质沉着症的临床和基础研究进展进行综述。     

Histological and ultrastructural features of nephrocalcinosis caused by a caries-reducing diet

Twelve Osborne-Mendel rats were given, for sixty days, an anticariogenic diet where 4% of the sucrose (2.7% of the diet) was replaced by an alkali phosphate salt combination (Na₂HPO₄+NaH₂PO₄·H₂O+KH₂PO₄; mole ratios 4.65/0.52/1.00 respectively). Nephrocalcinosis occurred in every animal as small concentric calcium deposits in the medulla and as large calcified masses higher in the cortex. A slight peritubular inflammatory reaction occurred and many exfoliated cells were seen in the lumina of the collecting ducts. In the electron microscope, calcified masses seemed to erode the tubular epithelium. No mitochondrial calcification in the epithelial cells, or calcification in the tubular basement membrane, were found. The cytosomes in a few proximal tubules displayed dark condensations. The ultrastructural features were similar to those found in connection with magnesium deficiency. No calcification was found in 7 controls or in 7 rats receiving the same basic diet with a 4% bicarbonate-phosphate supplement in the sucrose for four months. The appearance of nephrocalcinosis synchronously with a caries-protecting effect and apposition of dental calculus in animals fed on diet supplemented with alkali phosphate is discussed.

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Zusammenfassung 12 Osborne-Mendel-Ratten erhielten während 60 Tagen eine antikariogene Diät, in welcher 4% der Sucrose (entsprechend 2,7% der Diät) durch ein kombiniertes Alkaliphosphatsalz (Na₂HPO₄+NaH₂PO₄·H₂O+KH₂PO₄; Mol-Verhältnis 4,65/0,52/1,00) ersetzt wurde. Bei jedem Tier fand sich eine Nephrocalcinose, die als kleine konzentrische Calciumablagerungen im Mark und als große verkalkte Massen im Cortex sichtbar war. Peritubulär entstand eine leichte entzündliche Reaktion und im Lumen der Sammelrohre wurden viele desquamierte Zellen beobachtet. Elektronenmikroskopisch betrachtet, schienen die verkalkten Massen das Tubulusepithel zu zerfressen. Es wurden weder eine Verkalkung der Mitochondrien in den Epithelzellen noch Verkalkungen der tubulären Basismembran gefunden. In einigen wenigen proximalen Tubuli zeigten sich in den Cytosomen dunkle Verdichtungen. Die Eigenschaften der Ultrastruktur waren dieselben, wie man sie im Zusammenhang mit Magnesiummangel sieht. 7 Kontrollratten und 7 Ratten mit der gleichen Grunddiät, jedoch einem Sucrosezusatz von 4% Bicarbonat-Phosphat während 4 Monaten, zeigten keine Verkalkungen.Die gleichzeitige Entstehung einer Nephrocalcinose neben dem kariesverhütenden Effekt und der Anlagerung von Zahnstein bei Ratten, die mit einer zusätzlich Alkali-Phosphat enthaltenden Diät gefüttert wurden, wird diskutiert.

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Résumé Douze rats Osborne-Mendel ont été soumis pendant soixante jours à une alimentation anticariogène, où 4% de saccharose (2,7% de l'alimentation) a été remplacé par un mélange de sels de phosphate alcalin (Na₂HPO₄+NaH₂PO₄·H₂O+KH₂PO₄; les rapports molaires sont respectivement de 4.65/0.52/1.00). Use néphrocalcinose s'est développée chez chaque animal, sous la forme de petits dépôts de calcium concentriques dans la médulla, et sous forme de larges masses calcifiées dans le cortex. Une légère réaction inflammatoire est observée dans les canalicules et des cellules desquamées sont visibles dans la lumière des conduits collecteurs. En microscopie électronique, des masses calcifiées semblent érodées l'épithélium canaliculaire. Aucune calcification de mitochondrie de cellule épithéliale et de membran basale canaliculaire n'a été observée. Les cytosomes de quelques canalicules rénaux proximaux présentent des condensations sombres. Les caractères ultrastructuraux sont identiques à ceux observés au cours d'une déficience en magnésium. Aucune calcification n'est observée chez les 7 témoins et les 7 rats, soumis pendant 4 mois au même régime contenant 4% de bicarbonate-phosphate dans le saccharose. L'apparition d'une néphrocalcinose, l'effet d'inhibition de carie et la formation de tartre dentaire sont discutés chez ces animaux, recevant une alimentation contenant un phosphate alcalin.

     

The blood-brain barrier following experimental subarachnoid hemorrhage. Part 2: Response to mercuric chloride infusion

Under controlled physiological conditions, fresh blood was injected into the cisterna magna of 10 adult cats to produce subarachnoid hemorrhage (SAH). Damage to the blood-brain barrier (BBB) was induced 30 minutes after SAH by the intracarotid injection of a 6 x 10(-5)M solution of mercuric chloride (HgCl2). A control series of five cats received the same injection of HgCl2. Intravenously injected Evans blue dye was used to indicate areas of BBB damage. The lesions were confirmed by fluorescence microscopy. All control animals showed BBB damage in the hemisphere injected with HgCl2. Of the animals in the test group with SAH, 90% were free from lesions. When lesions were present, the distribution differed from that in the control group. These results bear a similarity to the reported absence of HgCl2 lesions during the acute stages after total cerebral ischemia. This suggests that the cellular components of the BBB participate in a general metabolic inhibition following SAH.     

Inhibition of airway hyperreactivity by oxybutynin chloride in subjects with cervical spinal cord injury.

OBJECTIVE: To further investigate mechanisms of airway hyperreactivity among subjects with chronic cervical spinal cord injury (SCI), we assessed airway responsiveness to aerosolized methacholine and histamine in subjects receiving chronic oxybutynin chloride therapy, and compared the findings with those not receiving the agent. METHODS: Twenty-five male subjects with cervical SCI participated in this study; 12 were maintained on oral oxybutynin chloride and 13 served as age-matched controls. Six of the 12 subjects receiving oxybutynin were challenged with aerosolized methacholine, and six with histamine; seven of the 13 control subjects were challenged with aerosolized methacholine and the remaining six with histamine. RESULTS: All 13 control subjects and all six oxybutynin/histamine subjects exhibited a significant bronchoconstrictor response (PC20 < 8 mg/ml), whereas mean PC20 values for the oxybutynin/methacholine group were > or =25 mg/ml. CONCLUSION: Our finding that the bronchoconstrictor effects of methacholine were blocked by oxybutynin chloride while those of histamine were not suggests that oxybutynin acts primarily through anticholinergic pathways rather than by causing generalized airway smooth muscle relaxation.