Sclerosing hemangioma of the lung in a young woman with cutaneous melanoma: the role of electron microscopy in preventing an erroneous diagnosis of metastasis

A young woman with a melanoma of the left forearm was found to have a right lung mass. This was initially interpreted as metastatic melanoma on the basis of clinical, radiographic, and light microscopic features, together with positive staining of tumor cells with antibody HMB-45. Electron microscopic examination performed for confirmation of the diagnosis revealed no evidence of melanocytic differentiation. Instead, there were features suggestive of the alternative diagnosis of sclerosing hemangioma (SH). This diagnosis was confirmed with additional immunocytochemical stains. To the authors' knowledge this is the first report of HMB-45 positivity in SH. This case illustrates a potentially disastrous diagnostic pitfall in interpreting lung tumors in patients with melanoma, and the vital role of electron microscopy in resolving conflicting and/or misleading immunocytochemical results.     

Tubular ultrastructure in acute renal failure in man: Epithelial necrosis and regeneration

Summary It is not clear whether tubular cell necrosis is present or not in acute renal failure (ARF) of ischaemic type (acute tubular necrosis). In order to get quantitative data, using precisely defined criteria for tubular cell necrosis, 25 renal biopsies from 24 patients with ARF (11 obtained in the active phase, 14 in the early recovery period) were compared with 12 control biopsies. In all 1959 proximal cells and 1603 distal cells were analysed by electron microscopy. Cellular disintegration was very rare in all groups. Shrinkage necrosis (apoptosis) was not present in the proximal tubules of the controls and was rare in ARF (1.6–2.1%). In the distal tubules of controls 2.7% of all cells showed shrinkage necrosis. The incidence in ARF was not significantly increased. Non-replacement sites in distal tubules (probablyloci where cells have recently been desquamated) were significantly increased in number (5.2%) in the active phase in ARF compared to controls and recovery. The relative number of regenerating cells was not increased.These data show that there is no widespread necrosis of tubular cells in ARF. The increased incidence in distal tubules of focal, denuded areas of the basement membrane in the active phase of ARF indicates a slightly increased desquamation of cells and/or a failure to cover such sites by adjacent cells. This process is not restricted to the brief induction phase of ARF but continues during the whole active phase.     

Electron microscopic detection of tin accumulation in biliopancreatic concrements after induction of chronic pancreatitis in rats by di-n-butyltin dichloride

The organotin compound di- n -butyltin dichloride (DBTC) is able to induce an acute and later a chronic pancreatitis in rats. In previous papers the authors demonstrated this DBTC pancreatitis as a rat model for an interstitial pancreatitis with tendency to transduction to the chronic form. DBTC is excreted according to its lipophilic nature by liver and bile. Therefore, the bilio-pancreatic main duct is necrotized by the tin-loaded bile. The duct system is blocked by cell debris and later by epithelial proliferations. In the chronic phase, numerous rats develop concrements in the main duct. In the present paper, the authors report about bacterial growth in some bilio-pancreatic concrements. Whereas the electron microscopic detection of tin by energy-dispersive X-ray analysis (EDX) in SEM or electron energy loss spectroscopy (EELS) in TEM was negative in the parenchyma of pancreas and liver, some concrements with bacterial cells were positive for this element. Tin mapping with energy spectroscopic imaging (ESI) in TEM demonstrated the congruency of tin signals and electron-dense particles inside these bacteria and of electron-dense accumulations in the matrix of these concrements. The low content of tin in pancreatic and liver tissue and the higher quantity of tin inside the bacterial contaminated concrements were supported by atomic absorption spectrophotometry (AAS). The paper discusses the long time preservation of tin in the concrements as an action of heavy-metal-accumulating bacteria, which should be classified in the future by bacteriological methods.     

Neuropeptide Y in the olfactory system, forebrain and pituitary of the teleost, Clarias batrachus

Distribution of neuropeptide Y (NPY)-like immunoreactivity in the forebrain of catfish Clarias batrachus was examined with immunocytochemistry. Conspicuous immunoreactivity was seen in the olfactory receptor neurons (ORNs), their projections in the olfactory nerve, fascicles of the olfactory nerve layer in the periphery of bulb and in the medial olfactory tracts as they extend to the telencephalic lobes. Ablation of the olfactory organ resulted in loss of immunoreactivity in the olfactory nerve layer of the bulb and also in the fascicles of the medial olfactory tracts. This evidence suggests that NPY may serve as a neurotransmitter in the ORNs and convey chemosensory information to the olfactory bulb, and also to the telencephalon over the extrabulbar projections. In addition, network of beaded immunoreactive fibers was noticed throughout the olfactory bulb, which did not respond to ablation experiment. These fibers may represent centrifugal innervation of the bulb. Strong immunoreactivity was encountered in some ganglion cells of nervus terminalis. Immunoreactive fibers and terminal fields were widely distributed in the telencephalon. Several neurons of nucleus entopeduncularis were moderately immunoreactive; and a small population of neurons in nucleus preopticus periventricularis was also labeled. Immunoreactive terminal fields were particularly conspicuous in the preoptic, the tuberal areas, and the periventricular zone around the third ventricle and inferior lobes. NPY immunoreactive cells and fibers were detected in all the lobes of the pituitary gland. Present results describing the localization of NPY in the forebrain of C. batrachus are in concurrence with the pattern of the immunoreactivity encountered in other teleosts. However, NPY in olfactory system of C. batrachus is a novel feature that suggests a role for the peptide in processing of chemosensory information.     

Quantitative study of the apical nerve fibers of adult and juvenile rat molars

The rat molar has become an important model for studies of interactions between nerves and the pulp-dentin complex, yet there is only limited quantitative information on the number and size distribution of axons entering the roots of this tooth. This study was undertaken to provide such a detailed characterization of the apical innervation of the rat molar. An additional objective was to compare the apical nerve composition of young, recently erupted rat molars with that of mature teeth in order to determine whether there is ongoing maturation of the innervation after the teeth have attained functional occlusion. A complete census was made of the nerve fibers entering the roots of both mature and recently erupted juvenile mandibular first molars in Sprague-Dawley rats. Each of the four roots of the first molars was processed for electron microscopy of thin sections near the apex. The majority of intradental nerve fibers entered the molar via the two larger (mesial and distal) roots. Within the apical root pulp, most, but not all, axons occurred within well-defined fascicles associated with blood vessels. Molars from adult animals (age 4 months) had a mean total of 232 (S.D. = 49, N = 7 teeth) myelinated fibers and 806 (S.D. = 143) unmyelinated axons entering the four roots. Fibers exceeding the Aδ size range (circumference ≥ 19 μm) accounted for only 4% of the myelinated axons at the apex. Molars from juvenile animals (age 4 weeks) had fewer myelinated fibers (mean 176, S.D. 18, N = 8), but more unmyelinated axons (mean 1,174, S.D. 160) than adults. The mean ratio of unmyelinated axons to myelinated axons was 6.6:1 for juveniles compared to 3.5:1 for adults. Juvenile teeth contained no myelinated fibers that exceeded 19 μm in circumference. These results indicate that the innervation of the rat molar resembles that of teeth of non-rodent mammals in that (1) innervation density is high, (2) there is a high ratio of unmyelinated axons, and (3) most of the myelinated fibers are of thin caliber. Furthermore, it appears that after the molar erupts, maturation of the nerve fiber composition continues with processes that include both a marked decrease in the number of unmyelinated axons and an increase in the number and size heterogeneity of myelinated fibers. © 1994 Wiley-Liss, Inc.     

Type VI collagen in mouse masseter tendon,from osseous attachment to myotendinous junction

Background and Methods: The association of masseter tendon type VI collagen with other extracellular matrix (ECM) components was examined from osseous attachment to myotendinous junction by immunohistochemistry and transmission electron microscopy with ATP treatment and enzyme digestion. Results: In the tendon proper, fibrocytes extended their processes among bundles of striated collagen fibrils and associated with adjacent cells through amorphous materials, thus forming a three-dimensional network. The amorphous or filamentous material was observed around the fibrocyte cell body and along the cell processes, where the localization of type VI collagen was confirmed by immunohistochemistry using anti-type VI collagen antibody. After treatment with 20 mM adenosine 5′-triphosphate (ATP), 100 nm periodic fibrils, an aggregated form of type VI collagen, were formed in the place where amorphous or filamentous material was present before the treatment. In myotendinous junction, the ATP-aggregated periodic fibrils were observed to associate with the external lamina of the muscle cells as well as among junctional tendon collagen fibrils. In the tendonbone boundary, ATP-aggregated periodic fibrils were observed around fibrocartilage-like cells in the uncalcifying area but not in the calcification front. Prolonged ATP treatment or hyaluronidase predigestion caused the formation of type VI collagen periodic fibrils in the area near the calcified matrix. Conclusions: The distribution of type VI collagen in mouse masseter tendon is different in different anatomical position. This may reflect the different functional demand for this collagen. © 1995 Wiley-Liss, Inc.     

Effect of inhibitors of electron transport and oxidative phosphorylation on trypanosoma cruzi respiration and growth

Antimycin A and 2-heptyl-4-hydroxyquinoline N-oxide, two specific inhibitors of the b-c₁ segment of the respiratory chain, affected the respiration of Trypanosoma cruzi epimastigote forms. The half-maximum inhibitory concentration were about 0.05 and 0.04 μg/mg cells (dry wt.), respectively. The maximum effect of antimycin (about 80% inhibition of respiration) was at about 0.1 μg antimycin/mg cells. Differential spectrophotometry of T. cruzi epimastigotes in the presence of antimycin, cyanide (or sulfide) and uncouplers, revealed the presence of functional cytochromes aa₃, b and c₅₅₈. In the stationary growth phase respiration by T. cruzi was completely inhibited by cyanide and effectively ihibited by sulfide, but in the expontential growth phase respiration was about 20% insensitive to 5 mM cynaide. Cyanide- and antimycin-insensitive respiration was completely inhibited by salicylhydroxamic acid (2 mM).Antimycin inhibited the operation of the tricarboxylic acids cycle in T. cruzi, as shown by the lesser production of ¹⁴CO₂ and by the modification of ¹⁴C distribution in epimastigotes incubated with [1-¹⁴C]glucose, [2-¹⁴C]acetate or NaH¹⁴CO₃. The inhibition of electron transport by antimycin increased the rate of the fumarate reductase reaction, an alternative electron pathway for the oxidation of reduced pyridine nucleotides.Addition of carbonyl cyanide 3-chlorophenylhydrazone to epimastigotes increased the rate of respiration and promoted the oxidation of reduced cytochrome b components, thus showing that these components are subjects to respiratory (acceptor) control. Pentachlorhenol similarly affected the cytochrome b redox level but did not modify the rate of respiration. The uncouplers released N,N′-dicyclohexycarbodiimide inhibition of respiration, and uncouplers and cyanide significantly decreased the ATP level in epimastigotes. The combined effects of the assayed inhibitors on respiration, cytochrome b redox level, ATP content and energy charge confirmed the operation of oxidative phosphorylation in T. cruzi epimastigotes. Antimycin, uncouplers and N,N′-dicyclohexylcarbodiimide inhibited growth of T. cruzi, thus proving the essential role of oxidative phosphorylation for the parasite.     

Inspissation of pancreatic zymogen material in cystic fibrosis

Cystic fibrosis is characterized by the elaboration of abnormal, thick, tenacious mucus resulting in obstructive disease in sites such as the lung and pancreas. In the pancreas, acinar plugs of mucus have been reported as the earliest recognizable morphologic lesion in cystic fibrosis. Since mucus is not normally elaborated within the pancreatic lobular tissue, the mechanism of accumulation of mucus in acini is enigmatic. To investigate this phenomenon, well-preserved autopsy pancreatic tissue was studied ultrastructurally. This study demonstrated very prominent mucous metaplasia in these diseased organs. Acinar plugs, though, developed before mucous metaplasia. Subsequent histochemical study was performed, which demonstrated that the early acinar plugs exhibited the same staining properties as zymogen granules and were distinct from the staining pattern of mucus in pancreatic tissue of cystic fibrosis patients. These findings, then, indicate that zymogen material, not mucus, becomes inspissated in the acini of the pancreas in early cystic fibrosis, and that subsequent mucous metaplasia occurs as the obstruction and exocrine atrophy progress.     

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.     

外源性三磷酸腺苷对人胃腺癌SGC-7901细胞的生物学效应

本文报道外源性三磷酸腺苷(ATP)对人胃腺癌SGC-7901细胞系增殖的抑制效应。在SGC-7901细胞的培养基质内加入ATP后,细胞生长明显受阻抑,4天以后,抑制率可达80％以上;癌细胞质膜上的3′,5′环腺苷酸磷酸二酯酶(cAMP-PDEase)活性明显下降,而细胞内的cAMP和纤维粘连蛋白的免疫荧光强度却明显增强。癌细胞多呈梭形,微绒毛减少,表面较光滑,呈现癌细胞向正常方向逆转的表型特征。本文还就ATP作用的机理进行了讨论。