An increased H2O2 production and a decreased activity of several peroxisomal oxidases have previously been reported in kidneys of rats with five-sixth nephrectomy, a model for chronic renal failure. We investigated the morphological and morphometric characteristics of peroxisomes, the organelles in which an important part of cellular H2O2 metabolism is localized, in remnant kidneys 16 weeks after operation. The vast majority of renal peroxisomes were found in the epithelial cells of proximal tubules. The organelles were distributed throughout the cells. We observed a significant increase in size, perimeter and volume density of the peroxisomes as compared to normal kidneys. Elongated peroxisomes were less frequent. An inverse linear correlation between mean size and number of peroxisomes was found. In cortex homogenates, the activity of catalase, the peroxisomal H2O2-scavenging enzyme, was significantly decreased and was inversely proportional to the mean peroxisomal diameter. The observed morphological adaptations are believed to create an unfavorable situation for the enzymatic activities in remnant kidney peroxisomes.

We report a patient with fibrinogen storage disease in which there was proliferation of normal-sized peroxisomes in the hepatocytes. This phenomenon has previously been described in several acquired liver diseases, We believe that this is an adaptation response due to decreased microsomal isoenzyme activity as a result of the excess accumulation of fibrinogen in the endoplasmic reticulum.

Hepatocellular peroxisomes harbor one of the metabolic pathways for ethanol metabolism (i.e., catalase in the presence of H2O2-generating enzymes). We studied the morphometric characteristics of these organelles in 26 biopsy samples of patients with different alcohol-induced lesions (12 with steatosis, 5 with hepatitis, and 9 with cirrhosis) and compared the findings with those obtained in seven control livers. All 33 human liver biopsy samples were stained for catalase activity to facilitate peroxisomal identification. Morphometric analysis of the peroxisomes was performed on calibrated electron micrographs. The numerical density of the peroxisomes was significantly increased to 183%, whereas the mean peroxisomal diameter (dcircle) revealed a significant decrease to 89%. This resulted in a normal volume density of the peroxisomal compartment, whereas the surface density was significantly induced. Peroxisomal shape was not different between alcoholic and control livers. When alcoholic livers were divided into three subgroups according to histopathological findings, similar morphometric results were obtained when compared with control livers, although significantly was sometimes lost. No differences in peroxisomal characteristics were found among alcoholic subgroups. The mean peroxisomal diameter per human liver (alcoholic and control) was inversely correlated to the numerical density. It is concluded that the peroxisomal adaptation in human alcoholic liver is such as to create an efficient environment for a presumably increased peroxisomal metabolism.

We investigated the hepatocellular peroxisomes in 27 patients with steatosis of the liver by means of catalase cytochemistry, light and electron microscopic study, and morphometry. Seven normal human livers were used as controls. In our patients, fatty liver was mainly associated with alcohol abuse or obesity. Indications for a slight decrease in catalase activity and for a proliferation were found by visual evaluation of the peroxisomes. Morphometric analysis showed a significant decrease in mean peroxisomal diameter (to 87%) and a simultaneous significant elevation in numerical density of the peroxisomes (to 188%); this resulted in a normal volume density and a significant increase (to 133%) in surface density. However, individual differences were found. No differences in peroxisomal characteristics were found between fatty livers of different causes. A significant inverse linear correlation between mean peroxisomal diameter and numerical density was found in patients with fatty livers. Because a similar correlation was also found when control data were added to the fatty liver data, we hypothesize that the peroxisomal compartment in human fatty livers is adapted in such a way to permit the same metabolic efficiency as in control livers.

To the Editor: I want to draw your attention to the viability of the human immunodeficiency virus (HIV) in cadavers and the implications of the presence of live HIV during embalming procedures in anatomy departments and during the dissection of embalmed cadavers by students. It is the policy of anatomy departments to keep the period between the death of a patient and the embalming of the body as short as possible to minimize degeneration. Recent findings indicate that HIV in a patient who died of AIDS is still infectious at the time of the body's arrival at the anatomy department . . .

In a patient with nodular regenerative hyperplasia of the liver, peroxisomes formed rows along the sinusoidal surface of the parenchymal cells, in contrast to their homogeneous distribution in the normal liver. In some cells, peroxisomes had a perinuclear configuration. Morphometric data were compared to those of seven control livers and revealed normal values of the peroxisomal diameter, axial ratio, volume density, numerical density and surface density. Peroxisomes with cytoplasmic invaginations, protrusions and gastruloid cisternae were rare. Angular profiles were frequently found. The peculiar distribution of the peroxisomes may be linked to the deficient blood supply to the liver in nodular regenerative hyperplasia.

Male NMRI mice were fed a diet with 10% w/w Beromegan for up to three weeks. Beromegan is a commercial fish (salmon) oil preparation rich in eicosapentaenoic acid and docosahexaenoic acid. Peroxisomal beta-oxidation capacity, catalase activity, and ultrastructural morphometry of the hepatic peroxisomes were investigated. In myocardium and kidney, catalase activity, peroxisomal staining after catalase cytochemistry, peroxisomal morphology, and morphometry (in myocardium) were evaluated. In liver, we found a significant increase in peroxisomal beta-oxidation, catalase activity, and peroxisomal number already after 3 days of dietary treatment. These changes were more pronounced after 3 weeks. Peroxisomal size was not changed. Positive correlations were found between peroxisomal enzyme activities and the number but not the size of the peroxisomes, and between catalase activity and beta-oxidation capacity. The mean peroxisomal diameter per animal was inversely proportional to catalase activity measured in homogenate. In myocardium, catalase activity was increased with duration of fish oil feeding. Peroxisomal staining, number, and size were also increased when compared to controls. In kidney, no alterations were observed. Our results indicate a beneficial effect of a diet supplemented with fish oil on the peroxisomal metabolism in liver and myocardium; it differs from the changes induced by xenobiotic peroxisome proliferation.

Background. Hepatic catalase activity is decreased in patients with malignant diseases, but little is known about the organelles that contain the bulk of catalase: the peroxisomes.Methods. The authors studied the hepatocellular peroxisomes in patients with malignant diseases by means of catalase cytochemistry, light and electron microscopic study, and morphometry.Results. Under the light microscope, a decrease in catalase staining was observed in 21 of 39 patients with extrahepatic tumors. A peculiar perinuclear concentration of peroxisomes was seen by light microscopic study in 15 of 39 patients and reflected an increase in number in most patients. In one of two hepatoma livers, peroxisomes also showed this perinuclear configuration. Ultrastructural and morphometric analysis of 20 livers of patients with extrahepatic tumors revealed a decreased mean peroxisomal diameter and an increase in number. Electron microscopic study also showed peroxisomes with transparent matrical spots, cytoplasmic invaginations, protrusions, and gastruloid cisternae. In each liver, at least one of these changes was observed. In hepatoma livers, one-third of the peroxisomes revealed empty matrical spots. In one patient, peroxisomes were smaller but more numerous.Conclusions. Alterations of the peroxisomal compartment are constant findings in the livers of patients with malignant diseases, but individual differences in peroxisomal alterations are frequent.

In the liver biopsy from an 8.5-year-old girl with the biochemical characteristics of rhizomelic chondrodysplasia punctata (RCDP), but with normal limbs, normal catalase-containing peroxisomes were absent. Light microscopy after diaminobenzidine staining for catalase activity (the peroxisomal marker enzyme) and immunostaining against catalase protein indicated a cytosolic localization of the enzyme. By electron microscopy, rare and extremely large, irregularly shaped vesicles were found in the parenchymal cells. The three peroxisomal beta-oxidation enzymes (acyl-CoA oxidase, bi(tri)functional enzyme, and 3-ketoacyl-CoA thiolase) and alanine-glyoxylate aminotransferase were immunolocalized in these organelles. However, a weak to negative label was obtained after staining against catalase. Diaminobenzidine staining demonstrated a minimal catalase reaction product in some vesicles only. Morphometry revealed a corrected mean d-circle of 1.44 microns and a maximum d-circle of 2.767 microns (controls: 0.635 microns and 1.027 microns, respectively). Numerical, volume, and surface densities were reduced to 3%, 41%, and 17% of control values, respectively. The large size, irregular shape, and rarity of the organelles are morphologic features of peroxisomal "ghosts." It seems that in this patient, apart from the known peroxisomal defects in RCDP, catalase incorporation into the peroxisomes is impaired together with a normal proliferation (division) of the organelles. In the cultured skin fibroblasts from the patient, however, immuno-electron microscopy showed normal catalase-containing peroxisomes in apparently normal numbers.

The present work extends tissue investigations previously performed in rat gastric mucosa on lipid metabolism alterations caused by n-3 and n-6 fatty acid-enriched diets. Liver and heart tissues are here studied and demonstrated to undergo, upon exposure to high fat diets with various n-3/n-6 fatty acid ratio contents, biochemical and morphological changes which may be enumerated as follows: (1) Rat liver peroxisomal prostaglandin E2, fatty acid but not bile acid beta-oxidation rates are enhanced, especially upon the diet with the higher n-3/n-6 fatty acid ratio. Mitochondrial beta-oxidation rates are little or not affected by the high fat diets. (2) Rat liver carnitine acyltransferases are stimulated by the high fat diets, the more rich the n-3 fatty acid content, the more pronounced the stimulatory effect. (3) Rat heart peroxisomal and mitochondrial beta-oxidation rates were increased in animals receiving the n-3 fatty acid-enriched diet. At a low n-3/n-6 fatty acid ratio content of the diet, these oxidizing rate values were in control range. The carnitine acyltransferase activities were increased in rat heart to different extents, depending on the n-3/n-6 fatty acid ratio content of the diet. (4) Ultrastructural examination and morphometric determinations on hepatocytes from rats receiving the diets with the lowest and the highest n-3/n-6 fatty acid ratio contents disclose that in the latter case the numbers and fractional volumes of peroxisomes and mitochondria are significantly higher than in the former case.

Hepatocellular peroxisomes in 32 patients with cirrhosis were studied by means of catalase cytochemical and morphometric analysis. Seven normal human livers were used as controls. The severity of the cirrhosis was determined with the Child-Turcotte criteria. Under the light microscope, a decrease in catalase staining was observed in 12 livers. Staining showed a weak inverse correlation with severity of the cirrhotic process. Peroxisomes revealed a perinuclear configuration in 24 patients. Morphometric analysis of peroxisomes was performed on 14 cirrhotic livers and revealed a near doubling of the number of organelles, with a compensatory decrease in mean peroxisomal diameter: no appreciable change in total volume of the peroxisome compartment was found. Cytoplasmic invaginations, protrusions and gastruloid cisternae were sparse. Apparently, peroxisomal proliferation in liver cells appeared early in the cirrhotic process. In all 10 livers with a perinuclear configuration of the peroxisomes that were processed for electron microscopy, a morphometrically confirmed increase in the number of peroxisomes was observed. Peroxisomes frequently showed transparent matrical spots and angular profiles. In two patients nucleoid-containing peroxisomes were observed. Although variation between individual patients was high, peroxisomal changes were observed in each cirrhotic liver. No relationship between morphological or morphometric alterations in peroxisomal compartment on one side and the severity of the disease or the type of cirrhotic nodules on the other side was observed.

We investigated hepatic catalase activity, and morphologic and morphometric alterations of hepatocellular peroxisomes after catalase cytochemistry, in mice given a diet supplemented with 10% Beromegan, a commercial fish oil preparation, for up to three days. Fish oil is rich in docosahexaenoic acid (C22:6 (n-3)) and in eicosapentaenoic acid (20:5 (n-3)). Hepatic catalase activity showed a gradual increase in mice fed this diet, being significantly increased (136 +/- 10 UB/g liver) after three days when compared top controls (85 +/- 11 UB/g liver). Light microscopy indicated an increase in peroxisomal staining and peroxisomal proliferation. The latter observation was confirmed by ultrastructural morphometry: number, volume density and surface density of the peroxisomes were more than doubled after a three day diet containing fish oil. Peroxisomal size was not changed. These alterations are suggestive for an increased peroxisomal metabolism induced by a diet rich in poly-unsaturated fatty acids.

The liver of an 8-year-old boy with congenital total lipodystrophy was investigated by means of catalase cytochemistry and morphometry. Comparison was made with eight human control livers. Light microscopy revealed cirrhosis and steatosis. Ultrastructural changes included lipid droplets with lamellae in the periphery, cup-shaped mitochondria, and nuclear pseudoinclusions. Peroxisomes were significantly increased in number but were not enlarged; they displayed various shapes and showed a moderate heterogeneity in catalase activity. A correlation between increased lipids and peroxisomal proliferation is suggested.

Peroxisomes are ubiquitous organelles containing enzyme sequences for beta oxidation of fatty acids, synthesis of bile acids, and ether phospholipids. In the inherited peroxisomal diseases one or more enzymes are deficient in hepatic, renal, and fibroblast peroxisomes. We have examined peroxisomes by light and electron microscopy in 29 duodenal biopsy specimens (21 with normal mucosa) after staining for catalase activity, a marker enzyme. Peroxisomes were most numerous in the apices of the nucleus and at the villus base. Two types were distinguished: rounded to oval forms with a median lesser diameter of 0.23-0.31 microns, and tubular, vermiform organelles 0.1 microns thick and up to 3 microns long. Both types coexist in most patients. Tilting of sections and examination of semithin sections at 120 kV did not show connections between individual organelles. By morphometry, volume density was at least 0.45-0.62% of cellular volume, compared to 1.05% in human liver. In contrast, in four out of five individuals surface density of the peroxisomal membrane was 1.4-2.3 times higher than in control livers; this is expected to favour the exchange of metabolites. We suggest that intestinal peroxisomes contribute substantially to the breakdown of very long chain fatty acids.

The peroxisomes in the liver of four patients with alcoholic hepatitis and in six patients with drug-induced hepatitis are compared to eight control livers by catalase cytochemistry and morphometry. A decrease of catalase activity is observed in alcoholic, amitriptyline, aprindine, clomipramine and methimazole hepatitis. Peroxisomes with a heterogeneous distribution of the catalase reaction product are found in most hepatitis livers. The number of organelles is increased 1.5 to 4.2 times in alcoholic, aprindine, methimazole and phenytoin hepatitis livers. In the last case, peroxisomes are also smaller. Changes in shape are seen in all hepatitis livers; they include invaginations, tails, funnel-like constrictions and gastruloid cisternae. In aprindine, phenytoin, methimazole and two alcoholic hepatitis livers, surface density exceeds the upper control value. These data indicate a loss of catalase activity in most hepatitis livers but also peroxisomal proliferation and shape modifications. It has been proposed that the latter changes are favorable for metabolic activity.

In addition to being found in peroxisomal diseases, peroxisomal alterations are also seen in viral hepatitis, though quantitative data are lacking. Experiments were performed on BALB/c mice. These mice were infected with Mouse Hepatitis Virus type 3 or were starved. The peroxisomes were cytochemically stained for catalase. Light microscopic, ultrastructural and morphometric analysis were performed. Several peroxisomal changes were observed 24 h after infection, and these changes became more pronounced after 40 h. There was a decrease in catalase activity, which was more pronounced in some regions, in some cells and in individual organelles; and there was also the onset of a progressive decrease in the number of organelles. It is believed that peroxisomes disappear by lysis. Proliferation probably occurs simultaneously up to 40 h after infection. At 48 h, necrotic foci are found to have swollen peroxisomes, and thus destruction is enhanced. Although peroxisomes seem to be sensitive markers of hepatic injury, they show a heterogeneous reaction pattern. Our results are discussed in relation to human viral hepatitis.