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Biomedical subjects

H Themann

Publications and source records attributed to H Themann.

At least 55 records · Page 3Linked to original sources
PubMed1981

Combined effects of vinblastine and vincristine on mouse hepatocytes with respect to ultrastructural elements.

The results of a single dose of the microtubule-destroying agents vinblastine/vincristine (0.5 mg/0.05 mg) on the ultrastructural elements of mouse hepatocytes was studied using the techniques of thin-sectioning and freeze-fracture following intravenous injection of the drugs. Several cytoplasmic modifications were observed in the hepatocytes. These included the storage of lipid droplets, a heavy accumulation of autophagosomes and vacuoles with very low density lipoprotein (VLDL)-like vesicles, large glycogen fields and dilated intercellular spaces with intrahepatocytic vacuoles. The rough endoplasmic reticulum exhibited pathological changes with loss of ribosomes and the bile canaliculi exhibited in some cases the loss of microvilli as well as dilatation of the lumen. The tight junctions surrounding the bile canaliculi exhibited alterations as well. The strands were reduced in number and showed a less organized arrangement. The gap junction showed an increase in size as well as an irregular outline in contrast to controls. These findings are interpreted as non-specific toxic phenomena. However, the possibility cannot be precluded that certain phenomena, such as alterations in the cell junctions, may be attributable to specific microtubule-destroying properties of the drugs.

Animals↗
PubMed1981

Structural relationship between desmosomes and mitochondria in human livers exhibiting a wide range of diseases.

Liver biopsies from ten patients (five women and five men, aged 25-63) with a number of different diseases were studied with a transmission electron microscope. In addition to many different pathologic changes in the hepatocytes, all clinical diagnoses showed 5-70% of mitochondria with paracrystalline inclusions. A peculiar finding was that the desmosomes that join two cells had mitochondria associated with the intracytoplasmic component in both cells in 5-15% of desmosomes observed. In addition, the association involved only one side in one cell in 7-23% of desmosomes observed. Only speculation can be made regarding the function of these mitochondrial-desmosomal associations.

Adult↗
PubMed1981

New aspects of the origin of hepatocellular vacuoles. An ultrastructural study on rat and mice liver after different intoxications.

The stages of vacuolar formations in liver parenchymal cells of rats and mice following application of phalloidine, amanitine, o-phenylphenol, hexachlorophene and p-chloro-m-cresol were demonstrated by electron microscopic investigations. After treatment the intercellular spaces are markedly widened and in restricted regions exhibit large sacculi penetrating into the cytoplasm of adjacent hepatocytes. In cross-sections these invaginations frequently appear as intracellular vacuoles. Our present investigations, however, clearly demonstrate that these vacuoles are still in direct connection with the intercellular space. The vacuolar formation is more pronounced in older animals and it is suggested that an increased patho-physiological portal hypertension leads to the swelling of the intercellular space.

Aging↗
PubMed1981

Ultrastructural changes in mouse hepatocytes exposed to vinblastine sulfate with special reference to the intercellular junctions.

The effects of a single dose (0.5 mg) of the antimicrotubular drug vinblastine sulfate on the ultrastructure of mouse hepatocytes was studied by thin sectioning and freeze-fracturing after intravenous injection of the drug. The following cytoplasmic modifications occurred in the hepatocytes: storage of lipid droplets, heavy accumulation of autophagosomes and vacuoles with very low density lipoprotein (VLDL)-like vesicles, pathological changes in the mitochondria, and dilatation of the Golgi complexes. From 30 minutes onwards the bile canaliculi appeared altered. The tight junctions surrounding the bile canaliculi became permeable to lanthanum. This increased permeability was correlated with a disorganized arrangement of tight junctional strands and localized interruptions within the zonulae occludentes. In contrast to controls the gap junctions appeared more numerous and larger in size, exhibiting a high degree of pleomorphism. In the cytoplasm gap junctional vesicles could be observed indicating the removal of gap junctions from the surface by a process of internalization. We cannot establish whether the described changes are a direct or indirect effect of vinblastine sulfate treatment. In view of the antimicrotubular effect of vinblastine sulfate we hypothesize that normal formation of gap- and tight junctions is dependent directly or indirectly on intact microtubules.

Animals↗
PubMed1981

Ultrastructural alterations in the mouse liver following vincristine administration.

The damage pattern in mouse liver was investigated following a single administration of 0.15 mg vincristine sulfate using the conventional thin-section technique and freeze-fracture. Numerous cytoplasmic changes were observed. Foremost of these was the increase in autophagosomes and vacuoles with very-low-density-lipoprotein (VLDL)-like vesicles. The rough endoplasmic reticulum exhibited a vesicular structure. The mitochondria also exhibited alterations such as enlargement and polymorphism. Both the interstitium and bile canaliculi were dilated. Lanthanum penetrated into the lumen of the canaliculi, i.e. the sinusoid/canaliculus compartmentalization did not remain intact, thus permitting bile to pass into the blood. Of particular significance are the alterations in the intercellular junctions. In contrast to the controls, the tight junctions were reduced and irregularly arranged. The gap junctions exhibited hypertrophy as well as a very irregular contour. The alterations may either be attributed to non-specific toxic effects of vincristine and/or the destructive properties of the agent on microtubules.

Animals↗
PubMed1981

Structure and function of the junctional complement of spontaneous and transplanted murine mammary carcinomas.

In this study the morphology of intercellular junctions in a murine mammary adenocarcinoma and in a solid carcinoma which resulted from continuous transplantations of this spontaneous tumor are described employing the techniques of ultrathin-sectioning after conventional fixation and tannic acid fixation and freeze-fracturing. The acini of the original adenocarcinoma are separated from the intercellular spaces by tight junctions which form a narrow belt-like zonula around the adluminal parts of all epithelial cells. The apical-to-basal width of the tight junctions varies from 0.4 to 0.8 micrometer. Desmosomes and gap junctions are located close to the zonulae occludentes. The size of gap junctions ranges from small spots 0.2 micrometer in diameter to large areas approximately 1.5 micrometer in diameter. In the solid carcinoma these cellular junctions appear without acinar organization randomly between the cells. In addition, special contact zones can be observed. The contact zones seem to be the precursors of a formation plaque for gap or tight junction formation. The sizes of the gap junctions show a wide range of variation, from as small as 5 particles to as large as 0.5 micrometer in diameter. Tight junctions do not form continuous belt-like zonulae indicating that they have lost their significance as a permeability barrier. They are interpreted as mechanical links. In addition to isolated gap junctions and tight junctions there exist gap junctions adjacent to tight junction fibrils suggesting a probable biogenetic relationship of these two structures.

Adenocarcinoma↗
PubMed1980

Ultrastructural morphometric investigations on rat liver of young and adult rats after treatment with technical pentachlorophenol (PCP).

Age-dependent effects of technical pentachlorophenol (PCP) on male rat livers were investigated after a 15 day treatment with PCP, 30 mg/kg/d body weight. The liver tissues were investigated morphometrically at light and electron microscopical levels. Statistically significant alterations of nuclei and organelles of the hepatocytes were described.

Adipose Tissue↗
PubMed1980

Ultrastructural morphometric analysis of human myocardial left ventricles with mitral insufficiency. A comparison with normally loaded and hypertrophied human left ventricles.

15 biopsies of dilated and hypertrophied human left ventricles in mitral insufficient hearts were morphometrically investigated. On light and electron microscopical level the results were compared with those received from normally loaded human left ventricles and from hypertrophied human left ventricles found in hearts with aortic valve disease. The results demonstrate alterations when compared with the results from normally loaded left ventricles. The differences between normally loaded and volume loaded left ventricles are smaller than those in pressure loaded left ventricles from aortic valve diseased hearts.

Adolescent↗
PubMed1980

Thin section and freeze-fracture studies of hexachlorophene induced alterations in the rat liver with special regard to intercellular junctions.

The ultrastructural changes in the liver cells of male Wistar rats induced by the oral and intraperitoneal application of hexachlorophene (HCP) were studied by using the freeze-fracture technique and by producing ultrathin sections. The rats were given the HCP once at a dose of 30 mg/kg body weight and were sacrificed 60 hours after treatment. The enlargement of bile canaliculi, the disorganization of tight junctions and the increase in number of gap junctions were the most prominent alterations observed in the liver cells. Furthermore, an increase in the smooth and rough endoplasmic reticulum and the microbodies were found. Pathological alterations in the mitochondria were also seen. In general, the effects of the intraperitoneal application on the liver were more pronounced than the effects of the oral application.

Animals↗
PubMed1980

A correlated thin section and freeze-fracture study of o-phenylphenol-indued alterations in the rat liver.

The ultrastructural changes in the liver cells of male Wistar rats induced by oral and subcutaneous application of o-phenylphenol were studied electron microscopically using the thin section and freeze-fracture technique. The rats were given the o-phenylphenol once at a dose of 2,500 mg/kg b.w. and were sacrificed 60 h after treatment. In the orally treated animals, alterations in the nuclei and nucleoli of the hepatocytes were the most prominent alterations. Furthermore, an increase in smooth endoplasmic reticulum, lysosomes and microbodies were found. After the subcutaneous injection of o-phenylphenol enlargements of the bile canaliculi, intercellular space and pathological alterations in the mitochondria were seen. A proliferation of the smooth endoplasmic reticulum, an increase of microbodies and a decrease in the rough endoplasmic reticulum could be found. Both groups showed an increase in small intracellular fat droplets in the hepatocytes. In general, the effects of the subcutaneous application on the liver were more pronounced than the effects of the oral application. Freeze-fracture replicas exhibited a disorganization of the zonulae occludentes and an apparent increase in the number and size of gap junctions. These alterations were interpreted as an attempt of the liver cells to counteract the intracanalicular pressure and to increase the mechanical stability of the liver tissue.

Animals↗
PubMed1980

Effect of extracorporeal blood irradiation on lymphocytes and the lymphatic tissue in a goat.

In a long-term study discontinuous extracorporeal blood irradiation (ECIB) was applied to a goat using a 500 Ci-137 Caesium source. Lymphocytes of the peripheral blood were examined by light and electron microscopy. After application of a transit dose of 466,500 rad the lymphocytes in the peripheral blood were found to be decreased from 6,900/microliter to 500/microliter, revealing a complete dissolution of the nuclei in electron microscopic preparations. Histological examinations showed a severe atrophy of the whole lymphatic tissue.

Animals↗
PubMed1980

The morphologic characteristics of intercellular junctions between normal human liver cells and cells from patients with extrahepatic cholestasis.

In freeze-fracture replicas the bile canaliculi of normal human livers showed a lumen of rather constant size with parallel margins. The zonula occludens consists of a complex anastomosing network of intramembranous ridges on the P face and complementary grooves of the E face of the plasmalemma of liver parenchymal cells. The zonula occludens is usually composed of three to five ridges running parallel to the lumen of the bile canaliculus that are surrounded by a looser meshwork of variable orientation. All tight junctions observed in control replicas appeared as continuous barriers without any disruptions. Extrahepatic cholestasis produced considerable morphologic alterations in the canaliculi and tight junctions. The lumen of the canliculi enlarged, and the microvilli disappeared. Side branches, irregularities, and outpouchings of the canalicular membrane extending into the cytoplasm of the hepatocytes were frequently observed. The complexity of the branching pattern and the number of strands in the zonulae occludentes changed extensively. Junctional strands away from their usual pericanalicular location were present on the lateral surface of the plasma membrane. The altered zonulae occludents contain regions in which the strands had a fragmented appearance or were completely absent. These discontinuities in the junctional meshwork provide a direct pathway between the lumen of the bile canaliculus and the intercellular space. They strongly suggest a leakage of the canaliculosinusoidal barrier. Of further interest is the diffuse aggregation of the usually randomly distributed intramembranous particles of the P face of the plasmalemma. The aggregates consist of 10-50 individual particles. Concomitantly, the desmosomes appeared to be more numerous than normally. The number and structure of gap junctions remained unaffected. The results of this investigation are discussed in relation to those obtained after experimental bile duct ligation in rats.

Adult↗