Gentamicin nephrotoxicity in rats. I. Acute biochemical and ultrastructural effects.

This investigation characterizes the acute biochemical and ultrastructural alterations within the rat kidney following the single injection of 10, 40, 80, or 160 mg. of gentamicin per kilogram of rat weight. Gentamicin was given intraperitoneally and rats were killed 80 minutes later. To assess a possible inhibitory effect upon protein synthesis 3H-leucine was injected 20 minutes postantibiotic and renal cortex was assayed for whole tissue and the protein fraction amino acid uptake. To exclude the possibility of gentamicin-induced lysosomal membrane instability with subsequent release of acid hydrolases, the activity of acid phosphatase was assayed in the supernatant and the residue of cortical homogenates containing the lysosomal fraction. Ultrastructural changes were concomitantly studied. To determine the intracellular localization of gentamicin, levels of the antibiotic were measured in subcellular fractions of cortical homogenates obtained from rats 2 hours following a single subcutaneous injection of 20 mg. of gentamicin per kilogram of rat weight. No gentamicin-induced alterations either of protein synthesis or of acid phosphatase distribution were demonstrated. Ultrastructural changes were most marked at 160 mg. per kg. consisting mainly of dilation of the endoplasmic reticulum, altered mitochondria, and increased cytosegresomes. Significant quantities of gentamicin were distributed within the nuclear, mitochondrial, and microsomal fractions. These studies indicate that although cytoplasmic alterations are prominent within the proximal tubular epithelial cells, they are not likely the result of either inhibition of protein synthesis or release of acid phosphatase from lysosomes.     

Malakoplakia of the prostate: a morphological and biochemical study.

A case of malakoplakia of the prostate is presented. Electron microscopic appearances support the origin of the Michaelis-Gutmann bodies from phagolysosomes in the histiocytes characteristic of the lesion. Biochemical analysis revealed the presence of muramic acid in the prostate with malakoplakia. This amino sugar is characteristic of bacterial cell walls and despite the absence of demonstrable bacteria in the affected tissues indicates the involvement of bacteria in the disease process.     

Time and dose-response study of the effects of vanadate on rats: morphological and biochemical changes in organs

Vanadate at a dosage level of 0.9 mg V/kg per day produced acute toxic signs in rats when injected subcutaneously for 16 days. These signs were weakness, loss of appetite, dehydration, significant reduction in body weight, nose bleeding, and death. The pathological and biochemical changes were most severe in kidney tissue. The kidney lesions were bilateral and multifocal. At two days, degenerative and necrotic changes of the tubular and glomerular epithelium, thickening of glomerular membrane, vascular congestion, and edema were observed. At five days, proliferation of tubular epithelial and interstitial cells was observed. At 12 days, the cellular proliferation in both cortex and medulla was significantly greater. Fibrosis was observed at glomerular tuft, preglomeruli, pretubules, and interstitium (cortex and medulla). At 25 days, the collagen deposition reached the highest level in all regions, cellular proliferation decreased, and thickening of the arteriolar wall became prominent. The renal lesions were coupled with changes in the levels of protein, RNA, DNA, and hydroxyproline. At 40 days, the kidney showed signs of recovery. Blood urea nitrogen levels were significantly elevated at 2-25 days post-treatment. Stained tissue sections from liver, lung, heart, spleen, thymus, lymph nodes, testes, and adrenal glands of the treated rats were examined microscopically and appeared normal. Biochemically, significant changes (p less than .05) in protein, RNA, DNA, and hydroxyproline were also observed in these organs. At lower dosage (0.6 mg V/kg per day for 16 days), similar but less severe pathological and biochemical changes in kidneys and other organs were observed. At 0.3 mg V/kg per day for 16 days, the changes in the tissues were detected only at the biochemical level. These results indicate that the toxic effects of vanadium are cumulative and that vanadium-produced fibrosis in tissues is dose-dependent.     

Dose-related protecting effects of vitamin C in gentamicin-induced rat nephrotoxicity: a histopathologic and biochemical study

Gentamicin remains the mainstay in treatment of gram-negative infections, despite its potential ototoxicity and nephrotoxicity. In this study, we investigated dose-related protecting effects of vitamin C against gentamicin-induced rat nephrotoxicity. Hence, 50 male albino Wistar rats were randomly divided into five equal groups to receive a corresponding dose of either normal saline as control, vitamin C (200 mg/kg/bw, i.m.) or gentamicin alone (80 mg/kg/bw, i.m.) or in combination with vitamin C at low dose (200 mg/kg/bw, i.m.; LVG) and high dose (600 mg/kg/bw, i.m.) for 9 days. Daily administration of gentamicin at a dose of 80 mg/kg resulted in a significant increase in oxidative stress in renal tissues and plasma and a concomitant decrease in the creatinine clearance and renal blood flow as result of early hemodynamic toxicity. Histopathological examinations revealed acute tubular necrosis with hyaline cast formation triggered by gentamicin over 9 days of experiment, in addition to interstitial nephritis and tubular epithelial loss. Further biochemical studies showed protecting effects of supplemented vitamin C at a high dose, including slowdown in the urinary enzyme activity, a significant decrease in plasma lipid peroxidation, and an increased tissue superoxide dismutase activity with recovery in the glomerular hemodynamicity and the ATPase activity up to 50% when compared to controls and low-dose rats (LVG). In high-dose animals, normal glomerular and tubular function on recovery from toxic renal failure led us to conclude that antioxidant properties of vitamin C consistently increase with dose intensity. The present study also provided evidence that high dose of vitamin C prevented both functional and histological renal changes induced by gentamicin in rats, more efficient than low dose of the vitamin.     

A morphological study of the effects of ozone on rat lung. I. Short-term exposure

In order to determine the effects of ozone on lungs and the course of cell renewal after damage, young male rats were exposed to 3 ppm of ozone for 4 hr. They were killed at 1, 6, 12, and 18 hr and 1, 2, 3, 4, 7, and 14 days after exposure. One hour before the killing, dividing cells were labeled with tritiated thymidine. Type 1 cells of centriacinar location and bronchiolar cells were severely damaged after exposure. Labeling indices of type 2 cells and bronchiolar nonciliated cells increased 1 day after exposure. Hyperplasia of type 2 cells and bronchiolar nonciliated cells was observed 2 and 3 days after exposure. Ciligenesis of bronchiolar ciliated cells occurred 4 days after exposure. Our study shows that injured type 1 cells are repaired by proliferation of type 2 cells and that injured bronchiolar ciliated and Clara cells are repaired by proliferation of bronchiolar nonciliated cells. These undifferentiated cells are probably progenitors of ciliated cells and Clara cells, and some nonciliated cells are in a transitional form between nonciliated and type 2 cells.     

A morphological study of the effects of 5-hydroxytryptamine and indomethacin on rat mesenteric venules.

A method is described for preparing venules of the rat mesentery for electron microscopy after the application of 5-hydroxytryptamine (5-HT) and pretreatment with indomethacin. Local application of 5-HT caused the leakage of colloidal carbon and the emigration of leucocytes into the venule wall. 5-HT also caused endothelial cells to bulge and their nuclei to contort. It increased the number of protrusions on both the luminal and abluminal surfaces of the endothelium and increased the width of the subendothelial space, and the degree of vesiculation in the endothelial cells. Systemic treatment with indomethacin significantly decreased the amount of carbon passing through the endothelium after the local application of 5-HT, but enhanced some of the other effects of 5-HT. Thus it increased the bulging of endothelial cells and contortion of their nuclei, and further increased the number of surface protrusions and the subendothelial space. It had no effect on the emigration of leucocytes resulting from the application of 5-HT.     

Remnant kidney pathology after five-sixth nephrectomy in rat. I. A biochemical and morphological study.

In Wistar male rats, hypertension was induced by 5/6 nephrectomy (5/6N). Body weight, blood pressure measurements, morphological and biochemical changes were followed (at four weekly intervals) for 12 weeks after 5/6N. Renal function was assessed by daily total urinary protein (TUP), plasma creatinine concentration [(Cr)p] and creatinine clearance rate. Plasma renin concentration (PRC), aldosterone concentration and erythrocyte content of sodium [Na]E and potassium [K]E were also investigated. Significant increases in systolic blood pressure (SBP), TUP, [(Cr)p] and [Na]E occurred after 4, 8, and 12 weeks of 5/6N. Progressive glomerulosclerosis (GSC), tubular atrophy and interstitial fibrosis were observed. Positive correlations were found between GSC and SBP and TUP. Positive correlations were also found between SBP and [Na]E and [(Cr)P]. PRC was not increased and showed no correlation with SBP. It is concluded that 5/6N produced hypertension associated with a series of morphological and biochemical alterations in kidney structure and function. In this model, mechanisms other than the renin-angiotensin system may be involved.     

Human pulmonary hypoplasia. Statistical, morphological, morphometric, and biochemical study.

Human pulmonary hypoplasia was studied statistically and pathologically in a large series of autopsy cases. Multiple logistic regression analysis indicated five independent risk factors from 10 statistically significant factors for pulmonary hypoplasia: (1) hydrops fetalis; (2) renal anomalies; (3) hernia, including diaphragmatic hernia and omphalocele; (4) skeletal anomalies; and (5) abnormalities of amniotic fluid, such as oligohydramnios and polyhydramnios. The characteristics of pulmonary hypoplasia for each factor were defined by morphological, morphometric, and biochemical methods. All bronchiolar branching, acinar complexity, and acinar maturation were retarded in hypoplastic lungs with hydrops fetalis, renal anomalies, affected side of diaphragmatic hernia, omphalocele, and skeletal anomalies. Only acinar complexity and maturation were impaired in the lung with oligohydramnios due to prolonged rupture of membranes. The pathogenesis of pulmonary hypoplasias should be considered differently with each associated anomaly and time of impairment. While impairment in early gestational stage before 16 weeks' gestation results in both reduced bronchiolar branching and retarded acinar development, that, at late stage, influences only acinar development.     

维生素E对镉中毒小鼠睾丸生精细胞保护作用的形态学研究

目的探讨维生素E(VitaminE,VE)对慢性镉中毒小鼠睾丸生精细胞损伤的保护作用。方法3月龄昆明种雄性小鼠60只,随机分3组:镉组(每次CdCl22mg/kg,皮下注射,每周2次,共3个月),VE组(染镉同时给VEl0mg·kg-1·d-1,灌胃)和正常对照组(注射等量生理盐水),用光镜、电镜观察生精细胞形态变化,并对精原细胞和精子的超微结构进行立体定量分析。结果(1)与正常对照组比较,镉组小鼠睾丸均受损,根据受损程度可分为轻、中、重3型;精原细胞胞核和精子头内细胞核的平均截面积、平均体积和平均表面积等形态参数值均显著缩小(P<0.05);(2)VE组:大部分小鼠睾丸的形态结构接近正常,仅少部分小鼠的睾丸受到轻、中型损伤;精原细胞胞核和精子头内细胞核的平均截面积、平均体积和平均表面积等形态参数值与正常对照组的相应值接近,无显著性差异(P>0.05)。结论VE对镉引起的小鼠生精细胞形态的损伤有一定保护作用。     

Protective effects of melatonin against spinal cord injury induced oxidative damage in rat kidney: A morphological and biochemical study

Spinal cord injury (SCI) induced oxidative stress affects multiple organ systems including the kidney. We studied the possible protective effects of melatonin on SCI-induced oxidative damage in renal tissues of rats. Wistar albino rats (n = 24) were exposed to SCI and divided into vehicle- or melatonin-treated SCI groups. Melatonin was administred intraperitoneally at a dose of 10 mg/kg for seven days. Renal tissues were investigated by light and electron microscopy. Furthermore, tissue malondialdehyde (MDA) and glutathione (GSH) levels and myeloperoxidase (MPO) and superoxide dismutase (SOD) activities were also determined. In the vehicle-treated SCI group, the renal histology was disturbed compared to controls, whereas the melatonin-treated SCI group showed significantly reduced degeneration of renal tissue as seen by both light and electron microscopy. MDA levels, MPO and SOD activities were increased and GSH levels were decreased in the vehicle-treated SCI group compared to controls. On the other hand, decreased MDA levels and MPO activities and increased GSH levels were observed in the melatonin-treated SCI group compared to vehicle-treated SCI group. These results showed that experimentally induced SCI caused oxidative stress in the rat kidney, whereas melatonin treatment reduced oxidative stress, suggesting that it may be used as a complementary therapy of renal problems occurring following SCI.     

Choice of tests in the biochemical assessment of nephrotoxicity in dogs and rats: A study with maleic acid

Urinalysis represents a useful tool in the evaluation of new pharmaceutical agents acting on the kidney, during preclinical toxcological studies. In the present study, we studied the response of urinary creatinine, LDH, AAP, ALP, β-GAL, GGT, NAG and protein excretion to a single intravenous dose of maleic acid (25 mg/kg for dogs and 100 mg/kg for rats). Enzymes were selected based on their association with renal toxicity and their localisation within the renal tubule. They included lysosomal, brush border and cytosolic enzymes. In male dogs, increases in enzyme excretion occurred within 2 h of maleic acid administration, peaked 3 h after dosing, and returned towards, or to, predose value at 24 h. Marked increases in enzyme levels occurred only for LDH and GGT (10-fold or more). Additionally, there was a marked increase in total protein excretion whereas creatinine excretion decreased. In male rats, the only major difference from control was a higher 0–24 h protein excretion rate (approximately 2-fold). Moderate increases were also present for ALP, GGT and LDH (< 2-fold). In female rats, there was a marked increase in urinary excretion of proteins and LDH, GGT, NAG and ALP (8–13-fold when compared to controls). There were only moderate increases (2-fold or less) in β-GAL and AAP. Creatinine was unaffected by the treatment. Histopathological examination of the kidney revealed moderate to severe proximal tubular necrosis in dogs and minimal to moderate tubular necrosis in rats. Overall, urinary GGT, LDH, total protein and creatinine concentrations are the most sensitive biochemical indicators of maleic acid nephrotoxicity in dogs. For rats, in addition to LDH excretion, total proteins, NAG, GGT and ALP can be considered to be sensitive markers of renal injury. In the light of these results and those reported in literature, it was concluded that the response of urinary markers of nephrotoxicity is heavily dependent on the nephrotoxic agent, the dose, species, sex and study design. Consequently, a range of markers should be examined in order to identify the most useful. Presented at ECCP97, Breda.     

Multiple hormone producing islet cell carcinomas of the pancreas. A morphological and biochemical investigation.

Biochemical, light, and electron microscopic studies of two multiple hormone producing metastic islet cell carcinomas of the pancreas are presented. Both tumors initially produced symptoms referable to a single hormone and over a period of years produced two other endocrine active polypeptides. The tumor in case 1 had been studied electron microscopically six years previously and had demonstrated no significant ultrastructural changes since then. The tumor in case 2 contained secretory granules of markedly varying size and density, suggesting a formation of packaged precursor molecules of possibly all three hormones. The pathogenesis of these tumors is discussed in light of recent evidence concerning the origin of endocrine cells.