The hepatic mitochondrial DNA depletion syndrome: ultrastructural changes in liver biopsies.

Mitochondrial respiratory chain disorders are an established cause of liver failure in early childhood. In some patients, the levels of mitochondrial DNA are markedly reduced, a condition referred to as mtDNA depletion syndrome (MDS). We report here on the ultrastructural changes in the livers of 10 infants with the hepatic form of this syndrome. All patients displayed progressive liver failure, neurological abnormalities, hypoglycemia, and lactic acidosis that warranted investigation of respiratory chain disorder in liver tissue, specifically expressing the disease. Decreased activity of respiratory chain complexes containing mtDNA-encoded subunits (complexes I, III, IV) was shown in 5 patients. Mitochondrial DNA depletion was confirmed by Southern blot analysis in the livers of 6 patients. We found hepatocytes filled with mitochondria having aspects of "oncocytic transformation," associated with numerous changes in shape, size, cristae, and matrix. The changes were virtually identical in all specimens. In many hepatocytes, microvesicular steatosis was the salient feature. Additional findings included cholestasis and focal cytoplasmic biliary necrosis (CBN), as well as cytosiderosis in hepatocytes and sinusoidal cells. In some hepatocytes the damage appeared extreme, but fibrosis was identified only in the few patients who died beyond 6 months of age. Although individual ultrastructural findings are not specific, when taken together, they show a diagnostic pattern highly suggestive of a respiratory chain disorder. In the appropriate clinical context, these findings can direct the clinician towards the diagnosis of hepatic MDS.

Localized amyloidosis in nasopharyngeal carcinoma diagnosed by fine needle aspiration and electron microscopy. A case report.

BACKGROUND: The association of amyloidosis and tumors is well known, but only rarely has it been found in the nasopharynx. Moreover, only a single case of tumor-associated amyloidosis in the nasopharynx has been diagnosed by exfoliative cytology and reported in the English-language literature. We describe a case of localized amyloidosis in metastatic nasopharyngeal carcinoma diagnosed by fine needle aspiration and confirmed by histology and electron microscopy. CASE: Bilateral neck enlargement appeared six months before consultation in a 57-year-old man. Both masses were resected, and during exploration of the nasopharynx, several blind biopsies were taken. Smears from the fine needle aspirate showed malignant epithelial cells, consistent with metastatic carcinoma, and Congo red stain showed the presence of amyloid. Histologic examination of the resected cervical masses and nasopharyngeal biopsies confirmed the diagnosis of nasopharyngeal carcinoma, nonkeratinizing variant with amyloid, and metastases in two lymph nodes. Electron microscopic examination of a lymph node showed extracellular, ribbon-like amyloid deposits as well as masses of amorphous amyloid, apparently intracellular. CONCLUSION: The origin of this form of amyloidosis is unclear in this patient since he had no other known etiologic factors for the condition. Increased awareness of the potential association of these two conditions and the use of fine needle aspiration may reveal a higher frequency than hitherto reported.

Macrophage-released proteoglycans enhance LDL aggregation: studies in aorta from apolipoprotein E-deficient mice.

Aggregated low-density lipoprotein (LDL) was shown to be present in the atherosclerotic lesion, but the mechanism responsible for its formation in vivo is not known yet. To find out whether LDL aggregation occurs in the arterial wall during atherogenesis, LDLs were extracted from the aortas of apolipoprotein E-deficient (E(0)) mice during their aging (and the development of atherosclerosis), and were analyzed for their aggregation states, in comparison to LDLs isolated from aortas of control mice. LDL isolated from aortas of E(0) mice was already aggregated at 1 month of age and its aggregation state substantially increased with age, with 3-fold elevation at 6 months of age compared to younger, 1-month-old, mice. Only minimal aggregation could be detected in LDL derived from control mice. Electron microscopy examination revealed that LDL particles from aortas of the E(0) mice were heterogeneous in their size, ranging between 20 and 300 nm. The mouse aortic LDL contained proteoglycans (PGs) and their content increased with the age of the mice, with about 2-fold higher levels than those found in LDLs derived from aortas of control mice. Macrophage-released PGs were previously demonstrated to enhance LDL aggregation in vitro. However, their involvement in LDL aggregation in vivo has not been studied yet. Thus, we next studied the effect of arterial macrophage-released PGs on the susceptibility of plasma LDL to aggregation by Bacillus cereus sphingomyelinase (SMase). Foam cell macrophages were isolated from aortas of the atherosclerotic E(0) mice at 6 months of age and were found to be loaded with cholesterol and to contain oxidized lipids. To analyze the effect of macrophage-released PGs on LDL aggregation, PGs were prelabeled by cell incubation with [35S]sulfate, followed by incubation of macrophage-released PGs with E(0) mouse plasma LDL (200 microg protein/ml) for 1 h at 37 degrees C. [35S]Sulfated PGs were found to be LDL-associated and the susceptibility of PG-associated LDL to aggregation by SMase was increased by up to 45% in comparison to control LDL. Similar results demonstrating the involvement of PGs in LDL aggregation were obtained upon incubation of LDL with increasing concentrations of PGs that were isolated from the entire aorta of E(o) mice (rather than the isolated macrophages). The stimulatory effect of macrophage-released PGs on LDL aggregation was markedly reduced when the PGs were pretreated with the glycosaminoglycan-hydrolyzing enzymes, chondroitinase ABC or chondroitinase AC, and to a much lesser extent with heparinase. We thus conclude that macrophage-released chondroitin sulfate PG can contribute to the formation of atherogenic aggregated LDL in the arterial wall.

Xanthogranulomatous appendicitis--an incidental finding of localized pathology.

The clinical, histopathological, and electron microscopic features of an unusual case of xanthogranulomatous appendicitis are reported. The patient, a 37-year-old female, presented with typical signs of acute appendicitis and the appendix appeared slightly dilated at laparatomy. The histopathological sections showed numerous xanthoma cells mixed with inspissated fecaliths. Electron microscopy disclosed the presence of xanthoma cells filled with electron-lucent lipid droplets of variable size. The ultrastructural characteristics of these cells enabled the distinction of two types of lipid-laden histiocytes, in relationship to the size of the lipid droplets. Since the lipid droplets were seen also in cells other than histiocytes, it appears that these changes are secondary to a common mechanism, comprising factors such as obstruction, hemorrhage, inflammation, and local hypoxia.

Carbonyl-iron supplementation induces hepatocyte nuclear changes in BALB/CJ male mice.

BACKGROUND/AIMS: In humans, chronic iron excess may induce hepatic fibrosis and/or hepatocellular carcinoma. This work was undertaken to investigate hepatic iron overload outcome in iron-overloaded mice. METHODS: BALB/cJ male mice received supplements of 0, 0.5, 1.5 and 3% carbonyl-iron for 2, 4, 8 and 12 months. Histological staining, immunohistochemistry using ferritin antibodies and electron microscopic studies were performed on liver. Liver iron concentration was measured biochemically. Mitotic index and hepatocyte nuclear size were evaluated on Feulgen-stained slides. RESULTS: Liver iron concentration was increased, reaching 13 times control value after 12 months in 3% iron-overloaded mice, and iron was found predominantly in hepatocytes, with a porto-centrolobular decreasing gradient. Neither hepatic fibrosis nor hepatocellular carcinoma was found. Perls' stain positive inclusions containing ferritin were found within hepatocyte nuclei in 3%-overloaded mice. Electron microscopy disclosed that inclusions consisted of ferritin particle aggregates without a limiting membrane. Mice overloaded with 3% iron for 12 months showed larger hepatocyte nuclei than control mice and a mitotic index increase with presence of abnormal tripolar mitotic figures. In addition, some iron-free hepatocytes were observed. CONCLUSIONS: Carbonyl-iron supplementation produces significant iron overload in mice but does not result in liver fibrosis or hepatocellular carcinoma after 12 months. However, nuclear changes were produced in hepatocytes, and occasional iron-free hepatocytes were observed: these may represent preneoplastic changes caused by iron overload.

Ultrastructural sequences during liver iron overload in genetic hemochromatosis.

BACKGROUND/AIMS: The pathway through which iron contributes to liver cell damage and cirrhosis in genetic hemochromatosis is not clear. The objective of the present study was to describe the ultrastructural changes in liver biopsies of patients in various stages of this condition and to correlate these with clinical, histopathological and biochemical data. METHODS: Liver biopsies from 20 patients with genetic hemochromatosis were examined by transmission electron microscopy. The use of unstained thin (60 nm) sections facilitated the identification and localization of the electron-opaque compounds ferritin and hemosiderin in various liver cells. Stained thin sections permitted evaluation of the concomitant subcellular damage and collagen deposition. The ultrastructural observations were corroborated with the histopathological findings and biochemical data. RESULTS: All patients had liver iron overload, which was classified as mild, moderate or severe. In the stage of mild overload (hepatic iron concentration HIC 93.5+/-23.3 micromol/g and hepatic iron index HII 2.3+/-0.7), cytosolic ferritin and scarce pericanalicular lysosomes (siderosomes) were seen in periportal hepatocytes (acinar zone 1), without evidence of organelle damage, and in the absence of sinusoidal cell siderosis. In moderate overload (HIC 190.8+/-41.5 micromol/g and HII 4.3+/-1.9), ferritin was identified in hepatocytes of all acinar zones, and the pericanalicular siderosomes were abundant, especially in acinar zone 1. Single hepatocytes showed organelle damage and occasional sinusoidal cells showed siderosis. In severe overload (HIC 308+/-49.0 micromol/g and HII 7.5+/-1.7), hepatocytes of all acinar zones were filled with large, hemosiderin-containing siderosomes, and changes in mitochondria, smooth and rough endoplasmic reticulum and nuclei were conspicuous. Marked sinusoidal cell siderosis and collagen deposition were observed predominantly in this stage. CONCLUSIONS: Electron microscopy has shown that during the long, latent stage of "compensated" genetic hemochromatosis, hepatocytes display only minimal subcellular changes, other than iron overload. "Decompensated" overload, characterized by extensive subcellular pathology and focal necrosis, is reached when 1) the hepatocytic siderosis is generalized (i.e. beyond pericanalicular polarization of siderosomes in hepatocytes, and beyond zone 1 in the acinus); and 2) there is evidence of massive siderosis of sinusoidal cells. These findings support the concept of a critical level of hepatic iron concentration beyond which organelle damage is conspicuous and liver cell injury may become irreversible.

The lipofuscin-iron association in pigmentosis tubae.

Pigmentosis tubae (PT) is a rare condition characterized by the presence of numerous lipofuscin-laden macrophages in the lamina propria of the fallopian tube. Two women, who also had endometriotic ovarian cysts, showed polypoid pigmented tubal mucosae. In addition to lipofuscin, occasional cells showed spotty positivity for iron. Ultrastructural examination of the tubal mucosa showed the lipofuscin-containing bodies, which were similar to lipofuscin-containing lysosomes found in other pigmented conditions. Cytoplasmatic ferritin and hemosiderin in siderosomes were observed in macrophages and endothelial cells of the lamina propria. The present study is the first to demonstrate the presence of iron-containing particles and lipofuscin in the residual bodies of PT. The origin of the excess iron is not clear, but erythrophagocytosis and an abnormal tubal environment could play a role. Iron-promoted lipid peroxidation may alter the lysosomal membranes and contribute to the excessive accumulation of lipofuscin in these cells.

Time-course of iron overload and biochemical, histopathological and ultrastructural evidence of pancreatic damage in hypotransferrinaemic mice.

1. The time course of iron overload of the pancreas in hypotransferrinaemic mice maintained on a standard rodent diet was compared with biochemical and histological markers of tissue damage. 2. Pancreatic iron levels increased linearly from weaning till 9 months of age [73.3 nmol/mg of tissue (SEM 9.9; n = 5) compared with 0.9 nmol/mg of tissue (SEM 0.1; n = 4) in age-matched controls] then decreased linearly till at least 18 months of age. 3. Investigation of tissue distribution of newly absorbed radioiron suggested that significant redistribution of iron from liver to pancreas (rather than direct dietary iron sources) must be invoked to explain the rate of pancreatic iron loading in hypotransferrinaemic mice. 4. Pancreatic epithelial cells first showed altered morphology at 9 months of age. At 12 months of age, the pancreatic epithelium had developed a micronodular appearance, with large numbers of acini replaced by atrophic, degenerated acinar cells. Increased collagen fibre deposition was evident by trichrome staining and by electron microscopy. Biochemical markers of pancreatitis (serum lipase, tissue pancreatitis-associated protein mRNA) were elevated before 9 months of age, whereas the levels of pancreatic amylase mRNA declined from 9 months of age. 5. The data suggest that iron loading of hypotransferrinaemic mouse pancreas proceeds up to a threshold level at 9 months of age followed by a progressive atrophy of secretory epithelium. The hypotransferrinaemic mouse pancreas is a useful model system for investigation of parenchymal cell damage by iron.

The application of laser microprobe mass analysis to the study of biological material.

Laser microprobe mass analysis (LAMMA) is an investigational method which is a powerful tool for the identification and quantitation of various elements present in small volumes of tissue. LAMMA is highly sensitive and capable of rapidly detecting concentrations of 1-3 p.p.m. of most metallic elements, in precisely localized cellular compartments. In order to further assess its value, cultured skin fibroblasts and biopsy tissues from human subjects and experimental animals were probed by LAMMA, and the results were correlated with ultrastructural findings. Biopsy samples were obtained from patients suffering from Gaucher disease, and from patients and animals with pathologic iron or copper metabolism. No significant abnormalities were detected in the cultured fibroblasts from patients with Gaucher disease, in contrast to the iron content of tissue biopsy Gaucher cells, which was markedly increased, apparently as a consequence of erythrophagocytosis. Particularly intense iron-related peaks were found in liver cytosiderosis due to neonatal or genetic haemochromatosis, thalassaemia major and in animal models of iron overload. An additional finding was the presence of aluminium accumulation in siderosomes of different cells. In liver biopsy samples from human Wilson's disease and from rats with an inherited disorder causing copper toxicosis, copper-containing compounds were identified and localized, and their relative concentration was estimated by LAMMA. The present study showed that LAMMA is a valuable technique for the localization and estimation of relative abundance of trace elements in various tissues containing excessive amounts of metals.

The hypotransferrinaemic mouse: ultrastructural and laser microprobe analysis observations.

Homozygote hypotransferrinaemic mice (hpx/hpx) have cytopathological features similar to those of human congenital atransferrinaemia, genetic haemochromatosis, and neonatal haemochromatosis. These conditions all have in common high levels of cytotoxic non-transferrin-bound serum iron. This study describes the ultrastructural features of iron overload in liver, pancreas, heart, and small intestine of 2- and 12-month-old hypotransferrinaemic mice. Electron microscopic studies of unstained sections showed early parenchymal cell siderosis, with accumulation of numerous ferritin particles and clusters in the cytosol, as well as ferritin and haemosiderin in lysosomes (siderosomes). In the 12-month-old animals, iron was also found in Kupffer cells and macrophages in other tissues. In addition, there were conspicuous iron-containing compounds in the bile canaliculi, and marked iron deposition in the pancreas and heart. Laser microprobe mass analysis (LAMMA) enabled localization and relative quantitation of iron deposition in subcellular compartments providing in situ documentation of iron accumulation in siderosomes and contributed in assessing total cytosolic iron in various cell types. Moreover, it demonstrated the importance and magnitude of the biliary route for iron excretion in these animals.

A new type of peroxisomal disorder with variable expression in liver and fibroblasts.

We describe two siblings, presently 5 and 9 years of age, who had neurodegenerative symptoms after the first year of life. Although they lacked clinical characteristics of a peroxisomal disorder, they had elevated levels of plasma very long chain fatty acids, pipecolic and phytanic acids, and abnormal bile acid intermediates, which suggested a generalized peroxisome deficiency disorder. Immunocytochemical study and electron microscopy of the liver disclosed absence of peroxisomes in approximately 90% of hepatocytes. However, the remaining 10% of the hepatocytes had numerous normal-looking peroxisomes containing catalase activity and catalase antigen. Alanine glyoxylate aminotransferase and the peroxisomal beta-oxidation enzymes acyl-coenzyme A oxidase and 3-ketoacyl coenzyme A thiolase were also present in the organelles. Both cell types were grouped in clusters. In contrast to most of the liver cells, fibroblasts cultured from skin biopsy specimens had normal peroxisomal functions. Thus this defect in peroxisome biogenesis is characterized by variable expression in different tissues (liver vs fibroblasts), as well as within individual cells in the same tissue (liver mosaicism). Awareness of the heterogeneity in tissue expression of peroxisomal disorders could be of critical importance in prenatal diagnosis.

Immunological diagnosis of childhood coeliac disease: comparison between antigliadin, antireticulin and antiendomysial antibodies.

The immunological markers proposed to supplement intestinal biopsy for the diagnosis of coeliac disease are antigliadin, antireticulin and antiendomysial antibodies. These antibodies have been studied separately or compared as pairs, but no prospective comparison of all three antibodies in childhood coeliac disease exists. Thirty-four confirmed coeliacs were compared with nine non-coeliacs with pathological small intestines, and 32 children with a normal intestinal histology. Sera were examined for IgG- and IgA-antigliadin antibodies (AGA) by ELISA, and for IgA-antireticulin antibodies (ARA) and IgA endomysial antibodies (EMA) by indirect immunofluorescence. In active coeliac disease, IgA-EMA was the most sensitive (97%), while IgA-AGA the least sensitive antibody (52%). The specificity of IgA-AGA, IgG-AGA, IgA-ARA, IgA-EMA was 95%, 92%, 100% and 98%, respectively. Positive predicted values of ARA and EMA were comparable (97-100%), while EMA had the highest negative predicted value (98%). Compared with IgG-AGA, IgA-EMA titres better reflected variations in dietary gluten, and correlated best with intestinal pathology. Compared with AGA and ARA sensitivity, specificity and predictive values, EMA is the most reliable serological marker for the diagnosis of coeliac disease. It reflects dietary changes in gluten and correlates best with intestinal histopathology. Therefore, it should be considered the best of the three serological tests available for childhood coeliac disease.

Serum carnitine concentrations in coeliac disease.

Carnitine is essential for muscle energy production and is required for the transport of long chain fatty acids and acyl co-enzyme A derivatives across the inner mitochondrial membrane. Recently, an absorptive transport mechanism was discovered at the small bowel level suggesting the possibility of a carnitine deficient state in patients with mucosal damage. Therefore, this study investigated carnitine concentrations in serum of patients with coeliac disease. Serum samples were obtained from 12 patients with active coeliac disease and seven with non-active disease, and compared with serum samples of 17 children with gastrointestinal symptoms but with a small bowel normal on biopsy examination and 33 normal controls. Total serum carnitine concentration was significantly lower in the patients with coeliac disease compared with the other two groups and to reference values. When the degree of atrophy of coeliac intestinal mucosa was numerically graded, serum carnitine concentrations did not correlate to the degree of the intestinal lesion but were significantly lower in the damaged intestine compared with the group with normal mucosa. It is suggested that coeliac disease should be considered as a potential cause of secondary carnitine deficiency.

Is eye cosmetic a source of lead poisoning?

Kohl is a lead-containing eye cosmetic applied to many infants in Israel and in other countries in the Middle East. Seven samples of kohl used in our region contained 17.3%-79.5% lead. We assessed 24 kohl users and 30 non-kohl users, aged 6-16 months, for blood lead, zinc protoporphyrin, hemoglobin, mean corpuscular volume (MCV), serum iron and calcium. Blood lead levels were significantly higher in the infants to whom kohl was applied (11.2 vs. 4.3 micrograms/dl, P less than 0.001) and were greater than 20 micrograms/dl in three of them. In the non-kohl users, blood lead levels were significantly higher in infants whose mothers used kohl (5.2 vs. 2.8 micrograms/dl, P less than 0.02). No significant differences were found in the other parameters. The kohl-using infants were significantly shorter at 3-5 weeks of age (P less than 0.005) but not at the time of the study. No significant differences were found in weight and head circumference at birth or at the time of the study between kohl-using infants and controls. Regression analysis showed that among the analyzed variables the infant's blood lead level was related only to the use of kohl. We conclude that application of kohl to the infant's or mother's eyes is associated with a significant increase in the infant's blood lead levels and in the minority of cases with asymptomatic lead poisoning.

Deferoxamine-induced iron mobilization and redistribution of myocardial iron in cultured rat heart cells: studies of the chelatable iron pool by electron microscopy and Mössbauer spectroscopy.

Iron mobilization by deferoxamine from iron-loaded rat heart cells in culture was studied by electron microscopy and Mössbauer spectroscopy to identify the chelatable iron pool. Studies in which iron 59 was used have shown a diminishing response to deferoxamine with increasing time intervals, which suggests a gradual transit from a more available to a less available storage iron compartment. Mössbauer spectroscopy showed that practically all iron mobilized by deferoxamine was derived from the small (less than 3.0 nm) recently acquired iron particles, which supports the "last-in, first-out" principle. Quantitation of cytosolic ferritin iron particles has shown a highly reproducible increase in cytosolic ferritin iron after deferoxamine treatment. This intracellular redistribution of iron stores is explained either by a reduced transfer of cytosolic ferritin into siderosomes or, more likely, by increased mobilization of membrane-bound iron deposits from insoluble polynuclear iron complexes in siderosomes and their subsequent incorporation into cytosolic ferritin. Thus the protective effect of deferoxamine on iron-loaded heart cells may be twofold: (1) net removal of excess iron by the formation of a stable complex of iron with deferoxamine and its secretion into the extracellular environment and (2) a shift of solubilized iron from membrane-bound deposits into the cytosol where iron is detoxified by its incorporation into the hollow shell of the ferritin protein.

Ferritin and hemosiderin in pathological tissues.

The biological importance of iron for most living cells has been under increasing attention during recent years. In addition to iron deficiency, iron overload has been recognized as a significant metabolic abnormality with potentially damaging consequences. The iron-storing compounds ferritin and hemosiderin have the unique quality of being ultrastructurally recognizable because of the electron-density of the iron concentrated within their particles. In this review, the electron microscopic features of iron overload are discussed, as found in various subcellular compartments and different types of cells and tissues. Defensive mechanisms against iron overload are exhibited by most cell lines and include: (1) the capacity of synthesis of the protein apoferritin by most cells whenever the concentration of ambient iron increases, (2) the capacity to bind toxic inorganic iron within the hollow shell of apoferritin; the transfer of the assembled iron-rich ferritin molecules into siderosomes and (3) the capability of further iron segregation within siderosomes by degradation of ferritin to hemosiderin. The study provides examples of cytosiderosis in different types of cells and tissues, as well as iron-related ultrastructural pathological changes.

The ultrastructural spectrum of lysosomal storage diseases.

After the important advances that have been made in the diagnosis of inherited lysosomal disorders with the help of biochemical-enzymic methods, the importance of electron microscopy for the identification and study of these conditions has apparently declined. Nevertheless, numerous specimens continue to be submitted for ultrastructural examination when lysosomal storage diseases are suspected. The article summarizes the present role of electron microscopy in this area and depicts typical specific findings in comparison with suggestive and nonspecific lysosomal changes. It is concluded that ultrastructural examination remains a useful and occasionally compulsory diagnostic method. In addition, it contributes to the identification of new diseases, the study of animal models of storage diseases, and the assessment of novel therapeutic methods such as bone marrow transplantation.