Hyaline Droplets Research Articles

SEMI-QUANTITATIVE IMMUNOHISTOCHEMICAL ANALYSIS OF MALE RAT-SPECIFIC α2u-GLOBULIN ACCUMULATION FOR CHEMICAL TOXICITY EVALUATION

We purified male rat urinary alpha(2u)-globulin, prepared the antibody in rabbits, and improved an immunohistochemical detection method using this antibody for male rat-specific alpha(2u)-globulin accumulation appearing as hyaline droplets in the kidneys. Our prepared antibody reacted specifically with alpha(2u)-globulin in both immunohistochemical and Western blotting analyses, furthermore, and the graded immuno-reactivities on the slide were well associated with computational image analyzing results. Using this method, we retrospectively analyzed the renal sections from the toxicity studies of 12 nephrotoxic chemicals, which had already been conducted under the Japanese Existing Chemicals Survey Program. We demonstrated that the hyaline droplets induced by treatment with 10 chemicals (1,4-dibromobenzene, dicyclopentadiene, 3,4-dimethylaniline, 1,4-dicyanobenzene, tetrahydrothiophene-1,1-dioxide, 1,3-dicyanobenzene, acenaphthene, 3,4-dichloro-1-butene, 3a,4,7,7a-tetrahydro-1H-indene and 3,5,5-trimethylhexan-1-ol) were directly associated with alpha(2u)-globulin accumulation. This immunohistochemical method is convenient for applying, even retrospectively, paraffin sections from general toxicity studies and could be useful for qualifying male rat-specific hyaline droplets consisting of alpha(2u)-globulin and renal risk in humans.

Effect of Betulonic Acid and Its Derivative [3-Oxo-20(29)-Lupene-28-Oyl]-3-Aminopropionic Acid on Liver Structure in Mice with RLS Lymphoma

Morphological study of the effects of semisynthetic derivatives of betulin (betulonic acid and [3-oxo-20(29)-lupene-28-oyl]-3-aminopropionic acid) on the liver of CBA/Lac mice with transplanted RLS lymphoma was studied in the control and after cytostatic polychemotherapy. The number of small focal necroses decreased, while the counts of hepatocytes in a state of slight hyaline droplet degeneration increased. Morphometry of the main elements of liver parenchyma showed that alanine amide derivative of betulonic acid decreases the severity of necrotic and degenerative changes in the liver parenchyma, induced by cytostatic polychemotherapy. Betulonic acid exhibited no appreciable hepatoprotective effect under these conditions.

Water-borne diclofenac affects kidney and gill integrity and selected immune parameters in brown trout ( Salmo trutta f. fario)

The detection of residues of various pharmaceuticals in surface waters during the last two decades has prompted concerns about possible adverse effects of this kind of pollution on aquatic organisms. The objective of the present study was to investigate effects of the non-steroidal anti-inflammatory drug diclofenac, one of the pharmaceuticals most prevalent in surface waters, on brown trout ( Salmo trutta f. fario), a salmonid species native to German rivers. Brown trout were exposed to 0.5, 5 and 50 μg/L diclofenac for 7, 14 and 21 days, whereby the lowest exposure concentration is comparable with concentrations commonly found in the aquatic environment. Fish exposed to diclofenac displayed significantly reduced haematocrit levels after 7 and 14 days of exposure. After 21 days, trout were examined for histopathological alterations, whereby diclofenac exposure resulted in increased monocyte infiltration in the liver, telangiectasis in gills, and the occurrence of interstitial hyaline droplets, interstitial proteinaceous fluid and mild tubular necrosis in trunk kidney. Concurrent immunohistological analysis revealed an increase of granulocyte numbers in primary gill filaments, as well as granulocyte accumulation and increased major histocompatibility complex (MHC) II expression in kidney, suggestive of an inflammatory process in these organs. Moreover, the ability of diclofenac to hinder the stimulation of prostaglandin E 2 synthesis was shown in head kidney macrophages of brown trout in vitro. These findings support the hypothesis that environmental exposure of fish to diclofenac provokes the same mechanism of action in these non-target organisms as previously described for mammalian species and can thus lead to similar (possibly adverse) effects. In general, the present study suggests that exposure of brown trout to diclofenac in concentration ranges commonly found in the environment can result in adverse effects in various organs and possibly compromise the health of affected fish populations.

Thirteen‐week Inhalation Toxicity of p‐Dichlorobenzene in Mice and Rats

Subchronic inhalation toxicity of p-dichlorobenzene (p-DCB) was examined by exposing BDF1 mice and F344 rats of both sexes (6 h/d and 5 d/wk) to inhalation of 25, 55, 120, 270 or 600 ppm (v/v) p-DCB vapor for 13 wk. The exposure to p-DCB vapor retarded the growth rate in the male mice, and induced hepatotoxicity in the mice and rats of both sexes and renal and hematological toxicity in the male rats. Hepatotoxicity was characterized by increased liver weight, hepatocellular hypertrophy, and increased serum levels of total cholesterol. Liver necrosis and increased serum levels of AST and ALT were observed in the exposed mice, whereas these changes, which indicate hepatocellular death, did not occur in any of the exposed rats. p-DCB-induced renal lesions occurred only in the male rats. Hyaline droplets were observed in the proximal tubular epithelial cells, and were stained positively with anti-alpha2u-globulin, suggesting excessive accumulation of alpha2u-globulin in the epithelial cells. Granular casts were formed in the tubular lumen, resulting from the necrotic desquamation of the renal tubular epithelium. Papillary mineralization in the renal pelvis and increased serum levels of BUN and creatinine were noted. These renal changes indicated alpha2u-globulin nephropathy. Decreases in red blood cell counts, hemoglobin concentration, hematocrit and mean corpuscular volume and increased spleen weight occurred in the exposed male rats. The NOAEL was 120 ppm for the hepatic endpoint in mice and for the renal endpoint in rats. The maximum tolerated dose for a 2-yr bioassay inhalation study of rodent carcinogenicity was estimated to be 300 ppm, based on the present results.

Nephrotoxicity of a novel antineoplastic platinum complex, nedaplatin: a comparative study with cisplatin in rats

The present study was designed to characterize the nephrotoxicity induced by the antineoplastic platinum complex nedaplatin (NDP) in rats of different ages in comparison with cisplatin (CDDP). A single dose of 15 mg/kg NDP or 7.5 mg/kg CDDP was administered intravenously to 8-, 11-, or 15-week-old male and female SD rats, which were then sacrificed after ten days. Body weight decreases were observed for both drugs, in direct relation to age. CDDP treatment markedly increased urinary excretion of NAG, gamma-GTP, LDH and protein, with peaks on day 4 and complete or partial recovery on day 7; NDP increased NAG, LDH and protein excretion, but to a lesser extent, and these elevations were generally more marked for females. CDDP increased plasma creatinine and BUN in males and females of all age groups at necropsy. No apparent changes were seen following NDP treatment except in the 15-week-old rats. These results also show that NDP is less nephrotoxic than CDDP. CDDP-treated rats showed remarkable proximal tubular lesions in the renal cortex and corticomedullary region, and the papillary lesions were minor. On the other hand, the NDP-induced nephrotoxicity was morphologically characterized by hyaline droplet changes (electron microscopically, hyperplasia of lysosomes), necrosis or hyperplasia of the collecting duct epithelium in the renal papilla and the epithelium covering the papilla. Cortical lesions, indicated by slight tubular dilatation, were found only in the animals with papillary lesions. In summary, NDP is a promising second-generation platinum complex with reduced nephrotoxicity.

Occurrence of hyaline droplets in renal biopsy specimens: an ultrastructural study

Hyaline droplets are apical cytoplasmic vesicles containing an accumulation of electron-dense amorphous materials surrounded by a unit membrane. Hyaline droplets may originate from apical vesicles after conversion to osmotic vesicles and loss of internally lined glycocalyx. They are found in the proximal tubular epithelium in biopsies from patients with renal diseases; however, their biological importance is not well understood. We reviewed ultrastructural pathology records of 140 renal biopsy patients to determine the occurrence and relevance of hyaline droplets. Of the cases, 14 (10%) showed the presence of hyaline droplets in proximal tubular epithelium. The distribution of cases were 8 of the 19 (42%) with minimal change nephritic syndrome, 2 of the 37 (5%) with IgA nephropathy, 2 of the 4 (50%) with membranous glomerulonephropathy, 1 of the 4 (25%) with tubulointerstitial nephritis, and 1 of the 1 (100%) with acute renal failure. The droplets were frequently found in male patients (86%), never in children, and were mostly associated with tubular necrosis (8 of 14 cases; 56%). Many hyaline droplets were observed in the cytoplasm of necrotic proximal tubular epithelial cells, and even when tubular necrosis was not evident, the proximal tubular epithelial cells containing hyaline droplets showed degenerated microvilli and decreased basal interdigitations. These results suggest that hyaline droplets could be one marker of renal tubular necrosis and a sign of functional disorder of protein reabsorption by degenerating proximal tubular epithelium.

Two-Week Oral Toxicity Study of 1,4-Dichloro-2-Nitrobenzene in Rats and Mice

Subacute toxicity of 1,4-dichloro-2-nitrobenzene (DCNB) was examined by feeding F344 rats and BDF1 mice of both sexes a diet containing DCNB at 625, 1250, 2500, 5000 or 10,000 ppm (w/w) for 2 weeks. All DCNB-fed rats survived to the end of the 2-week administration period, but 2 male and 6 female mice fed 10,000 ppm died during this period. The subacute toxicity was characterized by lesions affecting the liver, kidney, testis and hematopoietic system. The liver was the most responsive to DCNB, as evidenced by a dose-related increase in relative liver weight in rats and mice and centrilobular hypertrophy of hepatocytes in mice. An alteration in liver-associated lipid metabolism was suggested from the concomitant increases in serum concentrations of total cholesterol and phospholipid. A lower confidence limit of the benchmark dose yielding the response with 10% extra risk (BMDL10) for the relative liver weight indicated that rats were more responsive to DCNB than mice. The kidney lesion was characterized by alpha2upsilon-globulin-accumulated hyaline droplets in the renal tubular epithelial cells only in male rats, as indicated by positive anti-alpha2upsilon-globulin immunohistochemical staining. Testicular and hematopoietic lesions appeared at higher dose levels than did the liver and kidney lesions.

A TWO-GENERATION REPRODUCTIVE TOXICITY STUDY OF DICYCLOHEXYL PHTHALATE IN RATS

The reproductive toxicity of dicyclohexyl phthalate (DCHP) was evaluated in a two generation test in which male and female Sprague-Dawley (SD) rats of parental (F0) and F1 generation were exposed to DCHP in the diet at concentrations of 0 (control), 240, 1200 or 6000 ppm. With regard to the effects on the F0 and F1 parental animals, changes included inhibition of body weight gain and food consumption, diffuse hypertrophy of hepatocytes, and hypertrophy of thyroidal follicular epithelial cells at the doses of 1200 ppm and 6000 ppm. The following changes were observed in the 6000 ppm group: increase weights of the liver and thyroid, increased hyaline droplets in the renal proximal tubular epithelium (F0 and F1 males), reduction of prostatic weight (F1 males), and diffuse and/or focal atrophy of testicular seminiferous tubules (F1 males). In addition, slight prolongation of the estrous cycle was noted in the F0 females of the 6000 ppm group, along with reduced spermatid head counts in the testes (homogenation-resistant spermatids) in F1 male receiving doses of 1200 ppm or 6000 ppm. It is thought that the prolonged estrous cycle was secondary to the suppression of body weight gain. There were no test substance related changes in clinical signs and reproductive capability (mating, fertility, gestation and birth index), or in data for the delivery and lactational periods, or serum hormone levels. With regard to effects on the offspring, inhibition of body weight gain was found in the F1 and F2 6000 ppm, and decrease of anogenital distance (AGD) and appearance of areola mammae were observed in the F1 male 6000 ppm and F2 male receiving doses of 1200 ppm or 6000 ppm. No effects of DCHP treatment on the offspring were observed on results of clinical signs, the number of the pups delivered, sex ratio, viability, physical development, reflex and response tests, external abnormalities, organ weights, or necropsy findings. From the present study of DCHP administered to rats over two-generations, the no observed effect level (NOEL) for effects on the parental animals including the endocrine system, is considered to be 240 ppm. With regard to the reproductive toxicological effects on the parental animals, the NOEL is 240 ppm for males and 1200 ppm for females. For offspring, the NOEL values are concluded to be 240 ppm for males and 1200 ppm for females.

Thirteen-Week Oral Toxicity Study of l,4-Dichloro-2-Nitrobenzene in Rats and Mice

Subchronic toxicity of 1,4-dichloro-2-nitrobenzene (DCNB) was examined by feeding F344 rats and BDF mice of both sexes a diet containing 1,481, 2,222, 3,333, 5,000 or 7,500 ppm DCNB (w/w) for 13 wk. Oral administration of DCNB in feed to rats and mice retarded growth rates and induced subchronic toxicity affecting the liver, kidney, testes and blood. Liver and kidney were most responsive to DCNB. BMDL10 values for relative liver weight were 12.0 and 22.6 mg/kg/d for male and female rats, respectively, and 88.7 and 94.4 mg/kg/d for male and female mice, respectively. Increased liver weights and centrilobular hypertrophy of hepatocytes were observed in the DCNB-fed rats and mice of both sexes. Both increased serum activities of AST and ALT and liver necrosis occurred in the DCNB-fed mice. Increased incidences of hyaline droplets and granular casts in the proximal renal tubules were observed only in the DCNB-fed male rats, indicating alpha2v-globulin nephropathy. Eosinophilic droplets in the renal tubular cells and increased BUN concentrations occurred in the DCNB-fed female rats. DCNB-induced testicular and hematologic changes were noted in rats and mice. On the basis of these results, the highest dose level for the 2-yr bioassay study of rodent carcinogenicity was determined to be 2,000 ppm.

EVALUATION OF A TWO-GENERATION REPRODUCTION TOXICITY STUDY ADDING ENDOPOINTS TO DETECT ENDOCRINE DISRUPTING ACTIVITY USING LINDANE

A two-generation reproduction toxicity study in rats adding extra endpoints to detect endocrine disrupting activity was conducted using lindane by dietary administration at 0, 10, 60, and 300 ppm, for investigation of its utility. The extra endpoints included anogenital distance (AGD), nipple development, sexual maturation (vaginal opening and preputial separation), estrous cycle, spermatogenesis, sex organ weights, and blood hormone concentrations (thyroid and sex hormones). F1 offspring were examined for emotionality (open field test), motor coordination (rotarod test), as well as learning and memory (pole-climbing test). Hepatic drug-metabolizing enzyme activities were also measured. The results revealed general toxicological effects on parental animals, influence on reproductive function, and altered development of offspring; however, they did not demonstrate any distinct changes in the extra endpoints for detection of endocrine disrupting activity. Adult toxicity was observed in both F0 and F1 animals, including suppressed body weight gain and reduced food consumption in both sexes, and deaths of females at 300 ppm. Convulsions and irritability were observed during the perinatal period in pregnant F1 females given 300 ppm. Pathological examination revealed increased liver weights and centrilobular hepatocellular hypertrophy in both sexes and generations at 10 or 60 ppm and above; in addition, increased kidney weights and increased hyaline droplets in the proximal tubule epithelium, and basophilic renal tubules in males were noted at 10 ppm and above. Pituitary weights were decreased in F0 females and in F1 males and females and adrenal weights were increased in F1 males and females at 300 ppm; however, no histological changes were observed, and manifestations suggesting endocrine disrupting activity related to these changes were lacking. Hypertrophy of the thyroid follicular epithelium in F0 females at 300 ppm and in F1 males at 60 and 300 ppm, and decreases in T3 and/or T4 in both sexes and generations at 300 ppm were presumed to be secondary changes associated with the induction of hepatic drug-metabolizing enzymes. Blood hormone analysis revealed no changes in sex hormones attributable to lindane in males or females. Hepatic drug-metabolizing enzyme activities were increased dose-dependently from 10 ppm in both sexes and generations, with the rise in BROD activity being the most prominent. There were also increases in MROD, EROD, T-6beta-OH, and T4-UDP-GT activities (BROD >> EROD > MROD, T-6beta-OH, T4-UDP-GT). This suggests that while lindane most strongly induces CYP2B, it also upregulates a number of other drug metabolizing enzymes, such as CYP1A, CYP3A, and UDP-GT. As for effects on reproductive function, lack of maternal behavior, including lactation and retrieval behavior, and consequent total litter loss were observed in F1 dams at 300 ppm. There were no effects of lindane on the estrous cycle, spermatogenesis, mating, fertility, pregnancy, or parturition. Neonatal toxicity was observed in both sexes and generations, including suppressed body weight gain at 60 and 300 ppm, and decreased thymus and spleen weights without histological change at 300 ppm. The postnatal survival rate in F2 offspring was decreased due to lack of maternal behavior in dams at 300 ppm.

A thirteen week dietary toxicity study with 7-hydroxymatairesinol potassium acetate (HMRlignan) in rats

Plant lignan 7-hydroxymatairesinol (7-HMR) is a novel precursor of the mammalian lignan enterolactone. A 13 week toxicity study at dietary levels of 0, 0.25, 1, and 4% (w/w) of potassium acetate complex of 7-HMR (HMRlignan) was conducted in the Wistar rat. These dietary levels resulted in an average daily intake of 160, 640, and 2600 mg HMRlignan/kg body weight/day, respectively. A considerable systemic exposure of HMRlignan was verified by dose-related increases in plasma total (conjugated and unconjugated) concentration of 7-HMR and metabolites enterolactone, 7-hydroxyenterolactone, and matairesinol. Enterolactone appeared to be the major metabolite. Most (>96%) of the circulating 7-HMR and enterolactone was in conjugated form as measured from the low-dose rat plasma samples. HMRlignan exposure did not significantly affect clinical signs, ophthalmoscopy or neurobehavioural observations, and motor activity. Transient reductions in food intake and body weight gain in the mid-and high-dose group were ascribed to decreased palatability of the test feed. Only in males of the high-dose group the body weights remained slightly reduced throughout the study. In the high-dose group the number of thrombocytes (females), and total white blood cell count (males) were increased. Plasma triglycerides were dose-dependently depressed in males of all test groups and in females of the mid- and high-dose group, while plasma total cholesterol, and phospholipids were decreased in high-dose males. These changes, which have also been reported for other (flaxseed) lignans, were not considered to represent adverse effects. The relative weight of the kidneys was increased in males of the high-dose group. The weight of the full and empty caecum showed dose-related increases in males of all treatment groups and in females of the high-dose group. Absolute ovary weights were decreased in all treatment groups while decreases in relative ovary weights were confined to the mid- and high-dose group. In addition, a marginal lengthening of the estrus cycle was noted in high-dose females. Apart from prevention of hyaline droplet nephropathy in all high-dose male rats, there were no treatment-related histopathological alterations. It was concluded that HMRlignan showed weak antiestrogen-like activity which may be mediated through enterolactone metabolite. Based on declined ovary weight, the no observed adverse effect level of HMRlignan was set at 0.25% in feed corresponding to 160 mg/kg body weight/day.

Ultrastructural changes in various organs of the fish Puntius gonionotus fed cadmium‐enriched cyanobacteria

The accumulation and toxicity of cadmium in Puntius gonionotus fish that consumed the cyanobacterium Spirulina platensis contaminated with cadmium were studied. Fish were fed cadmium-contaminated cells for 4 weeks, after which cadmium accumulation in various organs was determined. The highest cadmium content was found in the kidney (56.0 microg Cd/g wet weight). Cadmium was not detected in the gill during the entire 4 weeks of cadmium feeding. Histopathological alteration of cells was observed in the gill, kidney, and liver. The results showed that dietary cadmium caused hypertrophy and edema of gill filaments. Coagulative necrosis and karyolysis of the nucleus were observed in the kidney. Vacuoles and hyaline droplets had accumulated in the epithelial cells of the proximal tubule. In the liver vacuolation of the cytoplasm, infiltration of macrophages, and focal necrosis were found. The ultrastructural changes that occurred in the cells of different organs were similar. These included a proliferation of vacuoles and lysosomes, formation of myelin bodies, degranulation, vesiculation, and dilation of rough endoplasmic reticulum, as well as swelling of mitochondria with loss of cristae.

Toxic effects of the non-steroidal anti-inflammatory drug diclofenac*1Part I: histopathological alterations and bioaccumulation in rainbow trout

Human and veterinary pharmaceuticals have been shown to occur in considerably high amounts in sewage treatment plant (STP) effluents and surface waters. The non-steroidal inflammatory drug diclofenac represents one of the most commonly detected compounds. Information concerning possible ecotoxicological risks of the substance are rather scarce. So far there are no data available on its possible effects in fish after prolonged exposure. In order to evaluate sublethal toxic effects of diclofenac in fish, rainbow trout ( Oncorhynchus mykiss ) exposed to diclofenac concentrations ranging from 1 μg/L to 500 μg/L over a 28 day period were investigated by histopathological methods. In addition, diclofenac residues in various organs were analyzed by means of gas chromatography/mass spectrometry (GC/MS). The histopathological examinations of diclofenac-exposed fish revealed alterations of the kidney such as an hyaline droplet degeneration of the tubular epithelial cells and the occurrence of an interstitial nephritis. In the gills, the predominant finding consisted in a necrosis of pillar cells leading to damage of the capillary wall within the secondary lamellae. The lowest observed effect concentration (LOEC) at which both renal lesions and alterations of the gills occurred was 5 μg/L. In contrast, the light microscopical examination of the liver, the gastro-intestinal tract, and the spleen did not reveal any histopathological alterations neither in diclofenac-exposed fish nor in solvent controls or control individuals. Chemical analysis showed a concentration-related accumulation of diclofenac in all organs examined. The highest amounts could be detected in the liver, followed by the kidney, the gills and the muscle tissue. Dependent on the diclofenac concentration used, the bioconcentration factors (BCF) were 12–2732 in the liver, 5–971 in the kidney, 3–763 in the gills, and 0.3–69 in the muscle respectively. From the present findings it can be assumed, that prolonged exposure in environmentally relevant concentrations of diclofenac leads to an impairment of the general health condition of fish.

Toxic effects of the non-steroidal anti-inflammatory drug diclofenacPart II. Cytological effects in liver, kidney, gills and intestine of rainbow trout (Oncorhynchus mykiss)

In the present study, cytopathology was investigated in the liver, kidney, gills and gut of rainbow trout ( Oncorhynchus mykiss ) exposed to five different concentrations (1, 5, 20, 100 and 500 μg/L) of the anti-inflammatory drug diclofenac under laboratory conditions. The lowest observed effect concentration (LOEC) for cytological alterations in liver, kidney and gills was 1 μg/L. In the gut, however, no diclofenac-induced cytopathology occurred. As the most prominent reactions induced by diclofenac (1) in the kidney, a severe accumulation of protein in the tubular cells (so called hyaline droplet degeneration), macrophage infiltration and structural alterations (dilation, vesiculation) of the endoplasmic reticulum (ER) in the proximal and distal renal tubules were observed. Furthermore, shortening of podocytes and their retraction from the basal lamina, a thickening of the basal lamina, the formation of desmosomes, and necrosis of endothelial cells in the renal corpuscles occurred; (2) in the liver, the most striking reactions were the collapse of the cellular compartmentation as well as the glycogen depletion of hepatocytes; (3) in the gills, pillar cell necrosis, hypertrophy of chloride cells, and epithelium lifting became evident in the secondary lamellae.

Toxic effects of the non-steroidal anti-inflammatory drug diclofenac: Part II. Cytological effects in liver, kidney, gills and intestine of rainbow trout ( Oncorhynchus mykiss)

In the present study, cytopathology was investigated in the liver, kidney, gills and gut of rainbow trout ( Oncorhynchus mykiss) exposed to five different concentrations (1, 5, 20, 100 and 500 μg/L) of the anti-inflammatory drug diclofenac under laboratory conditions. The lowest observed effect concentration (LOEC) for cytological alterations in liver, kidney and gills was 1 μg/L. In the gut, however, no diclofenac-induced cytopathology occurred. As the most prominent reactions induced by diclofenac (1) in the kidney, a severe accumulation of protein in the tubular cells (so called hyaline droplet degeneration), macrophage infiltration and structural alterations (dilation, vesiculation) of the endoplasmic reticulum (ER) in the proximal and distal renal tubules were observed. Furthermore, shortening of podocytes and their retraction from the basal lamina, a thickening of the basal lamina, the formation of desmosomes, and necrosis of endothelial cells in the renal corpuscles occurred; (2) in the liver, the most striking reactions were the collapse of the cellular compartmentation as well as the glycogen depletion of hepatocytes; (3) in the gills, pillar cell necrosis, hypertrophy of chloride cells, and epithelium lifting became evident in the secondary lamellae.

Toxic effects of the non-steroidal anti-inflammatory drug diclofenac: Part I: histopathological alterations and bioaccumulation in rainbow trout

Human and veterinary pharmaceuticals have been shown to occur in considerably high amounts in sewage treatment plant (STP) effluents and surface waters. The non-steroidal inflammatory drug diclofenac represents one of the most commonly detected compounds. Information concerning possible ecotoxicological risks of the substance are rather scarce. So far there are no data available on its possible effects in fish after prolonged exposure. In order to evaluate sublethal toxic effects of diclofenac in fish, rainbow trout ( Oncorhynchus mykiss) exposed to diclofenac concentrations ranging from 1 μg/L to 500 μg/L over a 28 day period were investigated by histopathological methods. In addition, diclofenac residues in various organs were analyzed by means of gas chromatography/mass spectrometry (GC/MS). The histopathological examinations of diclofenac-exposed fish revealed alterations of the kidney such as an hyaline droplet degeneration of the tubular epithelial cells and the occurrence of an interstitial nephritis. In the gills, the predominant finding consisted in a necrosis of pillar cells leading to damage of the capillary wall within the secondary lamellae. The lowest observed effect concentration (LOEC) at which both renal lesions and alterations of the gills occurred was 5 μg/L. In contrast, the light microscopical examination of the liver, the gastro-intestinal tract, and the spleen did not reveal any histopathological alterations neither in diclofenac-exposed fish nor in solvent controls or control individuals. Chemical analysis showed a concentration-related accumulation of diclofenac in all organs examined. The highest amounts could be detected in the liver, followed by the kidney, the gills and the muscle tissue. Dependent on the diclofenac concentration used, the bioconcentration factors (BCF) were 12–2732 in the liver, 5–971 in the kidney, 3–763 in the gills, and 0.3–69 in the muscle respectively. From the present findings it can be assumed, that prolonged exposure in environmentally relevant concentrations of diclofenac leads to an impairment of the general health condition of fish.

Inhalation two-generation reproductive toxicity study of methyl isobutyl ketone in rats.

To evaluate whether methyl isobutyl ketone (MIBK) affects reproductive performance, a two-generation reproduction study was conducted. MIBK was administered to 30 Sprague-Dawley rats/sex/group via whole-body inhalation at concentrations of 0, 500, 1000, or 2000 ppm, 6 h daily, for 70 days prior to mating. F(0) and F(1) females were exposed from mating through gestation day 20 and from postnatal day 5; F(2) litters were maintained through postnatal day 21. No treatment-related mortality of adult animals occurred. There was a dose-related increase in adult animals with no or a decreased response to a sound stimulus at 1000 and 2000 ppm; however, no adverse clinical signs occurred 1 h after exposure, suggesting this was a transient sedative effect. Clinical signs of central nervous system (CNS) depression in the pups were observed and one F(1) pup died after initial exposure to 2000 ppm on postnatal day 22; subsequently exposure was delayed until postnatal day 28. Decreased body weight gain and slight decreased food consumption were observed during the first 2 weeks of exposure in both generations at 2000 ppm. There were no adverse effects on male and female reproductive function or landmarks of sexual maturation. Increased F(0) and F(1) liver weights with associated centrilobular hypertrophy occurred in rats at 2000 ppm, indicative of an adaptive response. Increased male kidney weights at all exposure concentrations, associated with hyaline droplets, were indicative of male rat-specific nephropathy. Other than acute sedative effects, the no-observed-adverse-effect level (NOAEL) for parental systemic effects (excluding male rat kidney) was 1000 ppm, based on transient decreased body weight and food consumption; for reproductive effects, 2000 ppm, the highest concentration tested; and for neonatal toxicity, 1000 ppm (based on acute CNS depressive effects).

Slc7a9-deficient mice develop cystinuria non-I and cystine urolithiasis

Cystinuria is a common recessive disorder of renal reabsorption of cystine and dibasic amino acids that results in urolithiasis of cystine. Cystinuria is caused by defects in the amino acid transport system b0,+ (i.e. the rBAT/b0,+AT heteromeric complex). Mutations in SLC3A1, encoding rBAT, cause cystinuria type A, characterized by a silent phenotype in heterozygotes (phenotype I). Mutations in SLC7A9, encoding b0,+AT, cause cystinuria type B, in which heterozygotes in most cases hyperexcrete cystine and dibasic amino acids (phenotype non-I). To facilitate in vivo investigation of b0,+AT in cystinuria, Slc7a9 knockout mice have been generated. Expression of b0,+AT protein is completely abolished in the kidney of Slc7a9-/- mice ('Stones'). In contrast, Stones expressed significant amounts of rBAT protein, which is covalently linked to unidentified light subunit(s). Stones mice present a dramatic hyperexcretion of cystine and dibasic amino acids, while Slc7a9+/- mice show moderate but significant hyperexcretion of these amino acids (phenotype non-I). Forty-two per cent of Stones mice develop cystine calculi in the urinary system. Calculi develop during the first month of life and grow throughout the life span of the animals. Histopathology in kidney reveals typical changes for urolithiasis (tubular and pelvic dilatation, tubular necrosis, tubular hyaline droplets and chronic interstitial nephritis). The fact that some Stones mice, generated in a mixed genetic background, develop cystine calculi from an early age, while others do not develop them in their first year of life, suggests the involvement of modifier genes in the lithiasis phenotype. Thus, Stones provide a valid model of cystinuria which can be used in the study of genetic, pharmacological and environmental factors involved in cystine urolithiasis.

A Fast Histochemical Staining Method to Identify Hyaline Droplets in the Rat Kidney

A Fast Histochemical Staining Method to Identify Hyaline Droplets in the Rat Kidney

Alpha 2u-globulin nephropathy and carcinogenicity following exposure to decalin (decahydronaphthalene) in F344/N rats.

Decalin (decahydronaphthalene) is a widely used industrial solvent known to cause male rat-specific alpha2u-globulin nephropathy. In this project, 13-week and two-year inhalation studies of decalin were conducted consecutively in both sexes of F344/N rats. The key objectives were to (1) characterize the 13-week toxicity of decalin in rats, with an emphasis on nephropathy in males; (2) compare the kidney concentrations of decalin, 2-decalone, and alpha2u-globulin in males over 2 to 13 weeks of decalin exposure; and (3) correlate male rat nephropathy observed in the 13-week study with renal carcinogenicity in the two-year study. F344 rats (M/F) were exposed via whole-body inhalation to 0, 25, 50, 100, 200, or 400 ppm decalin for 13 weeks. Urine was collected at weeks 2 and 6 for creatinine and decalol analyses and at week 12 for clinical urinalysis. Right kidneys were collected from male rats at weeks 2 and 6 and from both sexes at week 13, homogenates were prepared using the whole kidney, and these homogenates were analyzed for alpha2u-globulin, decalin, and 2-decalone. Left kidneys were evaluated for histopathology and cell proliferation utilizing a proliferating cell nuclear antigen technique and counting proximal renal tubular epithelial cells to determine cell labeling indices. Necropsies and histopathologic evaluations were performed at week 13. Decalin exposure caused increases in kidney weight, urinalysis parameters (protein, AST, LDH), kidney alpha2u-globulin concentration, and proximal convoluted renal tubular cell proliferation in males. These changes were accompanied by microscopic lesions (accumulation of hyaline droplets in cortical tubules, regeneration of proximal tubular epithelium, and granular casts in medullary tubules) clearly linked to alpha2u-globulin nephropathy. Both decalin and 2-decalone were related to increased alpha2u-globulin in male kidneys. Kidney concentrations of decalin, 2-decalone, and alpha2u-globulin in exposed females were negligible, while females excreted greater amounts of decalol metabolites in urine than males at weeks 2 and 6. There were no exposure-related microscopic lesions in females. For chronic exposure, F344 rats were exposed via whole-body inhalation to 0, 25, 50 (males only), 100, or 400 ppm decalin for two years. Chronic exposure induced a spectrum of nonneoplastic and neoplastic lesions in the renal cortex of males, ranging from regenerative lesions of chronic nephropathy to tubular carcinomas. Incidences of renal tubular adenoma, tubular carcinoma, combined tubular adenomas and carcinomas, cortical tubular hyperplasia, hyaline droplet accumulation, hyperplasia of pelvic epithelium, and mineralization in renal papilla were increased in exposed males compared to controls. There was a clear increase in the mean severity of chronic nephropathy in decalin-exposed males. It was concluded that the carcinogenic effect on the renal cortical epithelium of male rats exposed to decalin was related to increased turnover of this epithelium, resulting from the cytotoxic effects of alpha2u-globulin accumulation in the renal cortical tubular cell cytoplasm.