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.

Prolactin and cortisol levels in various paroxysmal disorders in childhood.

The hormonal response of the anterior pituitary to various epileptic and nonepileptic events in children was studied. Postictal serum prolactin and cortisol levels were measured in 17 children with epilepsy, 23 with febrile seizures, and 10 with syncope or breath-holding spells. The levels were compared with those of 30 children with nonspecific fever, and 23 afebrile children served as control subjects. Significantly higher (P less than .01) prolactin levels (26.5 +/- 3.3 ng/mL, mean +/- SEM) were found in the epileptic group, compared with levels in children with febrile seizures (13.2 +/- 1.0 ng/mL), fever (11.2 +/- 0.9 ng/mL), syncope (7.3 +/- 0.9 ng/mL), and the control group (7.9 +/- 0.6 ng/mL). In contrast, serum cortisol levels were nonspecifically elevated in the epileptics and patients with febrile seizures or fever only. These findings suggest that elevated prolactin levels may be found after epileptic seizures and much less after febrile seizures, but not after breath-holding spells or syncopal events. Cortisol secretion appears to be nonselectively triggered by all stressful events, such as epileptic and febrile seizures, and fever. Elevated prolactin levels (greater than 15 ng/mL) associated with seizures may help in differentiating epileptic from febrile seizures or syncope.

Krabbe disease: increased incidence in a highly inbred community.

Krabbe disease (globoid cell leukodystrophy) was found with very high incidence (6/1,000 live births) in a large Druze kindred in Israel. The clinical data on 12 of the affected children demonstrated clinical variability even though these children are homozygous for the same mutation by descent from a common ancestor.

Johanson-Blizzard syndrome: clinical spectrum and further delineation of the syndrome.

We report on 2 patients with Johanson Blizzard syndrome and review the literature, in an attempt to further characterize the clinical spectrum of this disorder.

Ultrastructural abnormalities of liver cells in Reye's syndrome.

Electon microscopic observations were made on liver biopsy specimens from nine infants and children diagnosed as having Reye's syndrome by clinical, laboratory, and light microscopic criteria. In addition to excessive fat content, mitochondrial abnormalities were the most frequent abnormal finding in the liver. However, no correlation could be established between the severity of mitochondrial changes and clinical or biochemical data, and two patients with low levels of the first two urea cycle enzymes showed only mild mitochondrial abnormalities. Nonspecific or artifactual factors have been suggested to explain the mitochondrial changes. However, the data of this study suggest that most of the reported mitochondrial abnormalities are not artifacts, and that they can be helpful in the ultrastructural diagnosis of Reye's syndrome.

The scale of myocardial involvement in varicella myocarditis.

Two patients with varicella myocarditis are described. An arrhythmia associated with complete recovery occurred in the first patient whereas intractable congestive heart failure complicated by hemiplegia resulted in a fatal outcome in the other case. We stress the extent of myocardial involvement produced by the herpes zoster virus in the setting of varicella.

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.

Ocular abnormalities in chronic familial hyperphosphatasemia.

The ocular findings in two patients with Chronic Familial Hyperphosphatasemia are described in detail. They consist mainly of abnormal pigmentation, the presence of retinal folds of variable degree, and angioid streaks. It is suggested that these changes are in relationship to abnormal collagen metabolism and that CHF is not only a bone dysplasia but a more generalized condition with variable extraskeletal manifestations.

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.

Ultrastructural pathology of iron overload.

The study of the ultrastructural changes in the iron-laden organism has indicated the presence of a number of 'defensive' features, best understood if examined according to a concept of biological levels. At the molecular level, the main features are: the increased capacity of cells to bind toxic, inorganic iron to a specific storage protein, apoferritin, which becomes visible due to its iron-containing, electron-opaque core; since iron itself is involved in the de-repression of apoferritin synthesis, the number of assembled ferritin molecules depends on the amount of unbound iron present in the cell; there is a maximal, cell line-specific concentration of cytosolic ferritin; ferritin particles have a variable iron content, with richer molecules having a tendency to form clusters. At the cellular level, the transport of ferritin into the lysosomal compartment with formation of ferritin and haemosiderin-containing siderosomes enables further segregation of iron and permits cell survival even in the new steady-state of cytosiderosis. When siderosomes increase beyond a cell line-specific concentration, signs of organelle alteration followed by cellular death are noted. At the tissue level, the contributory ultrastructural observations include finding of early intercellular fibrosis, atypical (amorphous) iron deposition, as well as the accessibility of a detailed assessment of iron distribution in various cell types, i.e. endothelium, parenchymal cells, RE cells. The ultrastructural study of material obtained from human subjects with various stages of iron overload and of experimental animals facilitates the understanding of the process of iron overload itself and of the ensuing cellular damage. The recent emphasis on iron as a putative contributory factor in infections, as well as its role in neoplasia, has provided new directions for research, both clinical and experimental. Ultrastructural observations, combined with biochemical, immunological and biophysical investigations, are mandatory for providing answers to the numerous pending questions related to iron metabolism. Sequential electron microscopic studies of iron-laden cells enable the evaluation of chelating agents in either clinical or experimental conditions.

Iron and neoplasia: ferritin and hemosiderin in tumor cells.

Elevated serum ferritin levels have been reported in patients with malignant tumors and especially in those with neuroblastoma or breast carcinoma. The presence of the iron-storing compounds ferritin and hemosiderin in these tumors was therefore investigated. Some neuroblastomas, mostly of patients with advanced stages of disease, contained numerous ferritin particles randomly dispersed in the cytosol. Iron was also seen as ferritin clusters in the cytosol and as ferritin or hemosiderin in siderosomes. Morphometric study of ferritin particles as well as of the features of the siderosomes enabled the identification of two major types of iron-containing cells. In breast carcinoma most electron-opaque iron was found in siderosomes, with few ferritin particles being in the cytosol. The study points toward the hitherto unrevealed ultrastructure of cytosiderosis in neoplasms, the biological importance of which remains largely unknown.

Biological and ultrastructural aspects of iron overload: an overview.

The morphologic aspects of iron overload have been studied in human subjects, mammals, and birds with spontaneous overload, in a variety of experimental animals, and also in cell cultures. Reviewed here are the contributions of electron microscopy to the understanding of the iron-loading process, as reported during the last 12 years. The electron-density of ferrihydrite cores located within the protein shell of the ferritin molecule enabled its identification within either cytosol or lysosomes (siderosomes) of iron-exposed cells. The process of (holo)ferritin assembly, its transfer into siderosomes, and its degradation to hemosiderin can be followed in various cells. Siderosomes display cell-line-specific ultrastructural features, and different cell types show varying iron-segregating capacity. The study of experimental animals and cultured cells show that an iron-rich milieu may be damaging, probably through iron-catalyzed lipid peroxidation. Recent ultrastructural studies stress the value of describing initial alterations as opposed to the irrelevant end-stage findings. Further efforts should be directed toward elucidating the origin of iron in neonatal hemochromatosis, the role of iron in infection and neoplasia, and the nature and role of brain iron.

Primary hyperoxaluria type I: ultrastructural observations in liver biopsies.

The liver ultrastructure of four patients with the peroxisomal disease primary hyperoxaluria type I has been investigated. In all cases, peroxisomes of normal appearance were present in the parenchymal cells, except that they were somewhat reduced in number and size. In all patients, conspicuous lipofuscin was present, presumably resulting from the various metabolic disturbances to which the livers were subjected during the course of their disease. Considerable hepatocyte iron overloading was found in the three patients who had been hemodialyzed and/or had blood transfusions. Whether the relatively mild peroxisomal abnormalities (as compared to other peroxisomal diseases, such as Zellweger's syndrome) found in these hyperoxaluric patients are related directly to the peroxisomal deficiency of alanine:glyoxylate aminotransferase, or whether they are a secondary phenomenon, resulting from the consequent metabolic disturbance, remains to be elucidated.

Therapy of acute bacterial infections with cefaclor in a pediatric population: an open assessment.

Cefaclor, a new semisynthetic cephalosporin, was given orally as a suspension to 22 infants and children with acute otitis media and or/other infections, mainly of the respiratory tract, suspected to be of bacterial origin. The drug was found to be very easily accepted by the patients, and no side effects were encountered. Most patients became asymptomatic within 48 hours. Cefaclor is active against most bacteria producing acute otitis media, including ampicillin-resistant Hemophilus influenzae, and seems to be an effective bactericidal agent in the treatment of upper respiratory tract infections. Caution is recommended when used in bacteremic infants who do not respond promptly to therapy, in view of the poor cerebrospinal fluid levels of the drug and the danger of meningitis.

Ferritin in human liver cells of homozygous beta-thalassaemia: ultrastructural observations.

Homozygous beta-thalassaemia is a disease in which there is a progressive iron overload from infancy to death in early adulthood. Liver biopsies from 10 patients in various stages of this disease were examined by electron microscopy. A number of round or oval lysosomal structures, containing lamellae different from myelin figures, were seen in all patients, including those with minimal iron overload. Ferritin molecules were seen either in relationship with the lamellae forming arrays, or in paracrystalline arrangement, or with no organized form. There were practically no ferritin molecules in sub-cellular compartments other than cell sap and lysosomes. The density of cell sap ferritin was constant beyond infancy, but the number of iron-laden lysosomes increased with age. The stages in the process of iron seclusion, seen even in advanced phases of iron overload, are described. Ferritin is thought to accumulate in lysosomes by a transmembraneous movement, but other explanations are considered.