Ultrastructure of abnormal membrane inclusions in nuclei of human myocardial cells

Midgut cells alteration in gamma-irradiated beetles (Blaps polycresta, Coleoptera: Tenebrionidae)

Abstract This study was conducted to examine the effect of gamma radiation on biological specimens. Thus, our concept is to clarify that exposure to accumulated dose of 0.2 Gy gamma rays (0.66 rad/Sec. dose rate) from Cs137 source induces cellular perturbations in the midgut epithelium of the F1 progeny of Blaps polycresta, therefore affecting nutrition and growth. Beetles were reared in laboratory conditions and the newly emerged adults were irradiated with the aforementioned dose. Histological and ultrastructure anomalies of midgut cells (digestive and regenerative cells) were observed by 72 h after radiation exposure to ensure that the cells will not return to control state. Retardation in the development of the F1 progeny was also noticed and beetles died through two weeks. In the light of these observations, biological tissue act as an indicator to the continuous exposure to environmental radiation.

[Hypertrophic cardiomyopathy. Cardiomyocyte ultrastructure, the specific or stereotypic signs]

Hypertrophic cardiomyopathy (HCM) is a congenital disease caused by mutations in a number of sarcomere proteins. According to the type of mutation, clinical observations record similar clinical manifestations, myocardial pathological changes, and the timing of manifestation of the disease in HCM patients.

OBJECTIVE

To study cardiomyocyte (CMC) ultrastructural changes in the interventricular septum (IVS) of patients with HCM and evaluate their specificity for this pathology.

MATERIAL AND METHODS

IVS myocardial samples taken from 44 HCM patients aged 18-59 years at IVS myoectomy underwent an electron microscopic study. The diameter of CMCs and their nuclei was measured in semithin sections.

RESULTS

A morphometric examination of the IVS myocardium in HCM patients revealed moderate hypertrophy of CMCs and their nuclei, the diameters of which averaged 23.7±4.4 and 5.2±0.9 μm, respectively. The IVS CMCs were characterized by the ultrastructural signs of hypertrophy: the larger size and number of structures ensuring contractile and synthetic functions; the myocytes contained higher amounts of myofibrils, intermyofibrillar mitochondria, granular endoplasmic reticulum cisterns, and free ribosomes. On the contrary, some CMCs had fewer myofibrils in the perinuclear region, which is an adaptive change under hemodynamic overload conditions. In addition, a number of myocytes displayed signs of dystrophic changes: the appearance of lipofuscin granules, myelin figures, phagosomes, lipid droplets, and vacuoles, which can fill all free sarcoplasmic zones.

CONCLUSION

Ultrastructural changes characteristic of hypertrophy were found in IVS CMCs in HCM patients. In addition, there was partial myofibrillar loss and dystrophic changes in a number of myocytes, which are stereotypic compensatory-adaptive changes under hemodynamic overload conditions. All the above-mentioned changes in the CMC ultrastructure are characteristic of myocardial hypertrophy, but not specific for hypertrophic cardiomyopathy.

Incidences and range of spontaneous findings in control cynomolgus monkeys (Macaca fascicularis) used in toxicity studies

The authors performed a retrospective study to determine the incidences and range of spontaneous pathology findings in control cynomolgus monkeys. Data were collected from 570 monkeys (285 animals per sex), aged twelve to thirty-six months, from sixty regulatory studies evaluated at our laboratory between 2003 and 2009. The most common finding overall was lymphoplasmacytic infiltrates observed in the following incidence: liver (60.7%), kidneys (28.8%), heart (25.8%), salivary glands (21.2%), and stomach (12.1%). Inflammation also commonly occurred in the heart, kidneys, lungs, and stomach. The most common degenerative changes were localized fatty change in the liver, myocardial degeneration, and mineralization and pigment deposits in various tissues. Parathyroid, thyroid, and pituitary cysts; ectopic thymus in the parathyroid or thyroid gland; accessory spleen within the pancreas; and adrenohepatic fusion were among the most common congenital findings. Some incidental findings bearing similarities to drug-induced lesions were also encountered in various organs. It is hoped that the results presented here and elsewhere could form the groundwork for the creation of a reliable database of incidental pathology findings in laboratory nonhuman primates.

Alterations in myocardial cytoskeletal and regulatory protein expression following a single Doxorubicin injection

Immunochemical and ultrastructural studies of the rat heart after a single injection of doxorubicin (2.2 or 0.44 mg/kg) were performed. Ventricles were taken for the study 2 h and 3 weeks after injection. The light and electron microscopy and immunohistochemical determination of collagens of I, III, and IV types and fibronectin using specific antibodies were implied. Quantitive immunoblotting was used to analyze the expression levels of cytoskeletal and extracellular matrix proteins such as desmin, tubulin, vinculin, fibronectin, kinase-related protein (KRP or telokin), and smooth muscle/nonmuscle myosin light-chain kinase (MLCK). Doxorubicin (2.2 mg/kg) did not influence the relative volume and structure of collagen network but distinctly reduced the density of fibronectin distribution and decreased the content of tubulin, fibronectin, MLCK, and KRP. After 3 weeks, an increased density and extension of collagen network were observed, indicating the development of diffuse fibrosis whereas the content of tubulin and KRP increased above control level by 50 +/- 2.3% and 20 +/- 5.2%, correspondingly. Similar but less pronounced alterations were observed following the administration of 0.44 mg/kg doxorubicin. The content of MLCK after both doses consistently remained about 30% below its level in untreated animals. Isolated chick embryo cardiomyocytes subjected to doxorubicin responded by a 26% increase in KRP expression 4 days after whereas the level of tubulin expression remained unchanged. Thus, the damage of myocardium after a single injection of a therapeutic dose of doxorubicin was followed by an increased expression of selected cytoskeletal and extracellular matrix proteins, suggesting their involvement in cardiac reparation.

Intranuclear membranous profiles in germinoma cells--a variant of nuclear pockets and intranuclear annulate lamellae

When ultrastructurally examining 24 germinomas comprising 12 seminomas, 4 dysgerminomas, 1 mediastinal germinoma, and 7 intracranial germinomas, intranuclear membranous profiles were noticed in 17 germinomas, ranging from 20-100 nm in width and 3 microns in length. With occasional connections to the nuclear envelope through a small hole, intranuclear membranous profiles in germinoma cells were considered as clefts of the nuclear envelope. While most frequently situated under the inner nuclear membrane, they varied in configuration as well as distribution. As sequestered round mass of nuclear material, they were a variant of nuclear pockets containing nucleoplasm. Intranuclear annulate lamellae were occasionally present apart from the nuclear envelope and connected with nuclear clefts. Eleven of the twelve seminomas and 6 of the twelve non-seminomatous germinomas showed intranuclear membranous profiles, and the incidence of such profiles was much higher in seminomas than in non-seminomatous germinomas. Intranuclear membranous profiles facing the inner nuclear membrane were also noted in spermatogonia in adolescents and adults. It was suggested that intranuclear membranous profiles in germinoma cells could be structures following ones occasionally seen in spermatogonia.

Odontogenic myxoma. Surgical management and an ultrastructural study

Odontogenic myxoma is a tumor of primitive mesenchyme, probably derived from the dental apparatus. Surgical management of this benign but locally aggressive tumor is either by curettage or en bloc resection. Two cases of odontogenic myxoma of the mandible are reported. In one case, en bloc resection. Two cases of odontogenic myxoma of the mandible are reported. In one case, en block resection with immediate reconstruction was undertaken. In the second case, the neoplasm was thoroughly curetted. The first case was studied by electron microscopy. Six ultrastructural studies of seven odontogenic myxomas have been previously reported. The ultrastructural features of odontogenic epithelium that may be present in myxomas of the jaws have been examined by electron microscopy once before. Our observations are in agreement with those of other workers who suggest that the connective tissue cell is the proliferating component of the tumor and is very similar to a fibroblast but has enough ultrastructural and functional features to deserve the term myxoblast. The majority of the tumor cells are metabolically active and secretory and there is adequate evidence that the tumor matrix consists of large amounts of mucopolysaccharides. It is reasonable, therefore, to conclude that myxoblasts secrete the mucoid matrix that is so characteristic of odontogenic myxomas. Unlike normal or neoplastic fibroblasts, the myxoblasts are not engaged in abundant synthesis of banded collagen throughout the entire lesion.

Nuclear inclusions in alveolar epithelium of patients with fibrotic lung disorders

Ultrastructural study of pulmonary biopsy specimens from patients with fibrotic lung disease disclosed the presence of nuclear inclusions in 1% or less of cuboidal alveolar epithelial cells in 9 of 19 patients, including 6 of 12 patients with idiopathic pulmonary fibrosis, 2 of 3 patients with collagen-vascular disease, and 1 of 3 patients with sarcoidosis. Nuclear inclusions were not observed by ultrastructural study in 5 control patients. The inclusions consisted of masses or aggregates of tubules which probably were derived from the inner nuclear membranes. These tubules were smooth-walled, showed branchings and bifurcations, were composed of single trilaminar membranes, usually had a clear content, and ranged from 500 to 1000 A in diameter. They resembled nuclear tubules which occur in other cell types under conditions of rapid growth or specific hormonal stimulation. Statistically significant differences between the groups of patients with and without nuclear inclusions in cuboidal alveolar epithelial cells were not found with respect to smoking history, degree of fibrosis in the lung biopsy specimen, or the degree of pulmonary physiologic impairment. However, the average age of the patients having nuclear inclusions was significantly greater than that of patients not having nuclear inclusions. In addition, the frequency of indentations in the nuclei of cuboidal alveolar epithelial cells was greater in patients with nuclear inclusions than in patients without nuclear inclusions. Highly significant correlations were observed between the presence of nuclear inclusions and the presence of a) anchoring fibrils and hemidesmosomes along the basal surfaces of alveolar epithelial cells and b) multilayering of the alveolar epithelium.