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PubMed1962

Studies on the cornea. I. The fine structure of the rabbit cornea and the uptake and transport of colloidal particles by the cornea in vivo.

Physiological studies have demonstrated that ions, as well as large molecules such as hemoglobin or fluorescein, can diffuse across and within the cornea. Most of the substrates for corneal metabolism are obtained from aqueous humor filling the anterior chamber. In order to receive its nutrients and in order to maintain its normal conditions of hydration, the avascular cornea must transport relatively large amounts of solute and solvent across the cellular layers which cover this structure. It has been suggested in the past that there may be a morphological basis for the transport of large amounts of solvents and solutes by cells by the mechanism of pinocytosis. The use of electron-opaque markers to study fluid movements at the electron microscope magnification level was described by Wissig (29). The present study describes the fine structure of the normal rabbit cornea and the pathways of transport of colloidal particles by the cornea in vivo. Rabbit corneas were exposed in vivo to suspensions of saccharated iron oxide, thorium dioxide, or ferritin by injection of the material into the anterior chamber. In other experiments thorium dioxide or saccharated iron oxide was injected into the corneal stroma, producing a small bleb. Particles presented at the aqueous humor surface of the rabbit corneal endothelium are first attached to the cell surface and then pinocytosed. It appears that the particles are carried around the terminal bar by an intracellular pathway involving the pinocytosis of the particles and their subsequent transport in vesicles to the lateral cell margin basal to the terminal bar. Particles introduced at the basal surface of the endothelium (via blebs in the corneal stroma) are apparently carried through the endothelial cells in membrane-bounded vesicles without appearing in the intercellular space. There appears to be free diffusion of these particles through Descemet's membrane and the corneal stroma. The stromal cells take up large quantities of the particles when blebs are injected into the stroma.

Animals↗
PubMed1978

Anatomy of germinal centers in mouse spleen, with special reference to "follicular dendritic cells".

Lymphocyte proliferation in germinal centers (GC's) is thought to be triggered by antigen retained extracellularly on the surface of special "dendritic" cells. The anatomy and function of these cells have not been studied directly or in detail. We therefore examined mouse spleen GC's developing in response to sheep erythrocyte stimulation. We found that distincitve "follicular dendritic cells" (FDC's) were present in both the GC and adjacent mantle region of secondary follicles. The large, irregularly shaped nucleus, containing little heterochromatin, allowed for the light microscope (LM) identification of FDC's. By EM, the cell was stellate in shape sending out long, thin sheets of cytoplasm which could fold and coil into complex arrays. The processes were coated extracellularly by an amorphous electron-dense material of varying thickness, as well as particulates including variable numbers of virions. The FDC cytoplasm lacked organelles of active secretory and endocytic cells, such as well-developed rough endoplasmic reticulum (RER) and lysosomes. These anatomical features readily distinguished FDC's from other cell types, even those that were extended in shape. To pursue these descriptive findings, we injected three electron-dense tracers i.v. and sacrificed the mice 1 h-10 days thereafter. Colloidal carbon, colloidal thorium dioxide (cThO2), and soluble horseradish peroxidase (HRP) were actively sequestered into the vacuolar system of macrophages but were interiorized only in trace amounts by FDC's. Therefore, FDC's are not macrophages by cytologic and functional criteria. FDC's did display a unique property. Both colloidal carbon and thorium dioxide, which are nonimmunogens, could be visualized extracellularly on the cell surface for several days. The meaning of this is unclear, but the association of colloid with FDC's appeared to slow the movement of particulates through the extracellular space into the GC proper. FDC's were not readily identified in splenic white pulp lacking GC's. They must develop de novo then, possibly from novel dendritic cells that we have identified in vitro (Steinman, R. M., and Z. A. Cohn. 1973. J. Exp. Med. 137:1142-1162).

Animals↗
PubMed1980

Phagosome-lysosome fusion. Characterization of intracellular membrane fusion in mouse macrophages.

Several approaches have been used to study the determinants of phagosome-lysosome fusion in intact mouse macrophages. Lysosomes were labeled with the fluorescent vital dye acridine orange and the rate and extent of their fusion with yeast-containing phagosomes was monitored by fluorescence microscopy. Fusion was also assayed by electron microscopy, using horseradish peroxidase or thorium dioxide as a marker for secondary lysosomes. Good agreemen samples with an enzymatic marker, and thorium dioxide-labeled samples evaluated by stereology. The rate of usion as assayed by fluorescence was not affected by the number of particles ingested, serum concentration, or prior uptake of digestible or nondigestible substances. With this assay it was possible to observe the rate of fusion separate from and uninfluenced by the phagocytic rate. Both the rate and extent of fusion were dramatically increased after several days in culture and similar changes were found by use of the EM assays. Fusion was strongly affected by incubation temperature, having a Q10 of 2.5 No detectable fusion occurred below 15 degrees C, and this inhibition was rapidly reversed when cells were returned to 37 degrees C.

Cells, Cultured↗
PubMed2006

Natural radionuclides in the rocks of the Valle del Cervo Pluton in Piedmont.

Monitoring of the gamma radiation in Valle del Cervo Pluton was performed by determining U and Th contents in the main rock types cropping out over the entire area and pertaining to the granitic complex, syenitic complex and monzonitic complex. In particular, syenitic rocks were largely used as building and ornamental materials (e.g. Sienite della Balma). All the samples are fresh and do not present joints or fractures filled with U minerals. In the crushed samples the activity of uranium varies from 346 to 764 Bq/kg. Concentration of thorium varies from 202 to 478 Bq/kg. For all the analysed rocks uranium activity is higher than thorium one. The lowest value of radioactive concentration is referred to rocks of the granitic complex. The most active rocks are syenites. The data confirm the high activities of Valle del Cervo rock types, strongly connected with high K content of the source magma (geochemical signature); on the contrary, the activity seems to be not related to the location of the samples.

Air Pollution, Indoor↗
PubMed2001

Diapiric flow at subduction zones: a recipe for rapid transport.

Recent geochemical studies of uranium-thorium series disequilibrium in rocks from subduction zones require magmas to be transported through the mantle from just above the subducting slab to the surface in as little as approximately 30,000 years. We present a series of laboratory experiments that investigate the characteristic time scales and flow patterns of the diapiric upwelling model of subduction zone magmatism. Results indicate that the interaction between buoyantly upwelling diapirs and subduction-induced flow in the mantle creates a network of low-density, low-viscosity conduits through which buoyant flow is rapid, yielding transport times commensurate with those indicated by uranium-thorium studies.

Journal Article↗
PubMedDate not supplied

[Importance of studying exposure of the population to radon and its daughters].

INTRODUCTION: Radon and thoron are naturally-occurring radioactive gases, which are products of uranium and thorium decay series, respectively. Uranium and thorium occur widely in the environment, in rocks, soil, air, water, building materials, humans, etc. Radon daughters in the air are predominantly attached to aerosols. A minor part, normally less than 10%, occurs as unattached atoms or ions. The relative distribution of attached daughters in indoor air and equilibrium factor depend on many variables, such as the decay constant, the concentration and size distribution of aerosols and ventilation rates. Increased ventilation decreases the concentration of radon and daughters in the air. OCCURRENCE: Concentration of radon, thoron and their decay products in the air indoors, in mines or houses, is higher than outdoors. In houses, the level of radon daughters may be enhanced by radon from radium rich building materials, landfill, soil and bedrock under the house, radon rich water and by poor ventilation. CONCLUSION: In recent years, several evaluations of human health risks and estimations have been made in regard to the dose-response relationship and lung cancer risk attributable to inhaled radon daughters. Inhalation of radon and thoron daughters leads to deposition in the human respiratory tract and consequent irradiation. Deposition depends on various factors, such as the size distribution of aerosols to which the daughter products of radon are attached, and fraction of unattached daughters. On average, the dose to the basal cell layer in the lung is about 5 to 8 times higher than the dose in the pulmonary region.

Air Pollutants, Radioactive↗
PubMed1990

Cholangiocarcinoma occurring after childhood radiotherapy for Wilm's tumor.

Some patients have been given radioactive thorium dioxide as an intravascular contrast agent. Retained particles of thorium in the liver have chronically irradiated hepatic tissues and sometimes caused cholangiocarcinomas and other malignancies. We studied a young woman who developed cholangiocarcinoma in liver tissue which was included in the field of external beam therapy given for Wilm's tumor some twenty years earlier. Radiation-induced cholangiocarcinoma may not necessarily require chronic exposure to ionizing radiation.

Adenoma, Bile Duct↗
PubMed1979

Angiosarcoma of the spleen: a report of two cases and review of the literature.

Results of the ultrastructural study of one of two cases of splenic angiosarcoma established the blood vessel origin of this tumor. Fifty-three previously reported cases were reviewed. None of the 55 patients had a history of exposure to thorium dioxide, vinyl chloride, or arsenic, which are known to be associated with hepatic angiosarcoma and other tumors. A comparison of the splenic and hepatic angiosarcomas showed that tumors not associated with exogenous material frequently involve the spleen and liver simultaneously, and that tumors associated with thorium dioxide, vinyl chloride, or arsenic commonly involve the liver with sparing of the spleen.

Adult↗
PubMed1988

Thorotrast-associated gliosarcoma. Including comments on thorotrast use and review of sequelae with particular reference to lesions of the central nervous system.

The occurrence of a glioblastoma with sarcoma, a gliosarcoma, in the left frontal-temporal area of a 49-year-old woman with a history of Thorotrast exposure, is described. Thorotrast-laden histiocytes and free Thorotrast material were found in both components of the tumor. An overlying, adherent dural cranial lesion was found to contain massive deposits of Thorotrast embedded in a dense fibrotic and sclerotic stroma with focal calcification. These features are typical of "Thorotrastoma." Thorotrast stains greenish-brown with hematoxylin and eosin and appears as refractile granular particles of relatively uniform size either within histiocytes or as free material. The radioactivity of the deposits was confirmed through the use of a scintillation counter, and 232 thorium was definitively identified though the use of scanning electron microscopy with energy-dispersive X-ray analysis. Immunohistochemical studies of the tumor demonstrated glial fibrillary acid protein (GFAP) immunoreactivity in areas of glioma and focal vimentin and actin immunoreactivity in areas of sarcoma. Thorotrast-associated lesions of the central nervous system (CNS) are infrequently reported, and a Thorotrast-associated gliosarcoma has not yet been reported. The use of Thorotrast, its radiobiology, and sequelae are reviewed with particular emphasis on lesions occurring in the CNS.

Brain Neoplasms↗
PubMed1984

Efficacy of different DTPA treatment schedules for removal of 234Th from simulated wounds in rats.

The translocation of 234Th from a simulated wound site and the efficacy of DTPA administration, as a function of the thorium compound injected as well as the DTPA treatment schedule, have been investigated in rats. Much more 234Th injected as citrate was translocated from the injection site than after administration as nitrate, whereas the distribution pattern of 234Th translocated to the various tissues was nearly identical for both 234Th compounds. Combined local and systematic treatment with DTPA was equally or more effective than each of the treatments alone in reducing the retention of 234Th at the injection site and in the organs.

Animals↗
PubMed1963

ENDOTOXIN-INDUCED TOLERANCE TO TOXIC MANIFESTATIONS OF CANDIDA ALBICANS.

Hasenclever, H. F. (National Institutes of Health, Bethesda, Md.) and William O. Mitchell. Endotoxin-induced tolerance to toxic manifestations of Candida albicans. J. Bacteriol. 85:1088-1093. 1963.-Mice exposed to 425 r total body irradiation failed to become tolerant to Candida albicans toxicity after injection with lipopolysaccharide. Mice injected with lipopolysaccharide and then X-rayed did not demonstrate the tolerant state. An injection of thorium dioxide in mice that had previously received tolerance-inducing amounts of lipopolysaccharide rendered them as susceptible to acute C. albicans toxicity as control mice. A bimodal manifestation of tolerance was noted. Groups of mice given single injections of lipopolysaccharide at 6 or 1 days before challenge demonstrated high levels of tolerance, whereas the tolerance in mice given a single dose at 3 days was negligible. The bimodal effect was not observed in tolerant mice challenged with lipopolysaccharide. Injections of viable or nonviable pathogenic fungi known to produce tolerance to the toxicity of C. albicans in recipient mice did not produce tolerance to lipopolysaccharide. Serum from mice injected with lipopolysaccharide showed in vitro inhibitory activity for C. albicans.

Animals↗
PubMed2002

[Synthesis and spectral characterization of U(VI) and Th(IV) complexes of thenoylpyrazolone-ethylenediamine].

Two novel bis-schiff base complexes [UO2 (PMTHP)2en] and [Th(PMTHP)2en(NO3)2] have been synthesized, where (PMTHP)2en = N,N'-bis[(1-phenyl-3-methyl-5-oxo-5-pyrazolinyl)- 2-thenoylmethylidyne] ethylenediamine, and characterized by elemental analysis, IR, UV-Vis, 1H NMR, 13C NMR and molar conductance measurements. The results show that the bis-schiff base is a quadridentate ligand and the nitrate a bidentate ligand, and the uranyl and thorium ions exhibit coordination of six and eight in the complexes, respectively.

Chelating Agents↗
PubMed1975

Malignant peritoneal mesothelioma after cholangiography with thorotrast.

Reported is a 59-year-old patient, who died of a peritoneal mesothelioma 36 years after contamination with thorotrast of the peritoneal cavity during cholangiography at cholecystectomy. Eleven years before death, the right kidney had to be removed for hydronephrosis due to fibrous stenosis of the pyeloureteral junction, because of thorium dioxide deposits.

Cholangiography↗
PubMed1979

Thorotrast-associated sarcoma of bone: A case report and review of the literature.

An osteosarcoma developed near the right lesser trochanter of a 55-year-old woman. The neoplasm fulfilled the generally accepted criteria for a Thorotrast related malignancy. Strengthening this relationship was the occurrence of the tumor in an unusual location and uncommon age group. Thorium was confirmed both in the tumor and in bone marrow histiocytes by its characteristic x-ray spectrum. Including this case only twelve Thorotrast-associated neoplasms of bone have been reported. The mean latency period after Thorotrast administration was 26 years. Regression analysis revealed that latency period and Thorotrast dose are inversely related. All tumors were reported to be sarcomas. Six osteosarcomas, one fibrosarcoma, one chondrosarcoma, and one undifferentiated sarcoma were proven histologically. All patients, for whom follow-up was given, had died of the tumor. The reasons behind the low frequency of reported Thorotrast-associated bone malignancies may be the low concentration of 232Th and radioactive daughters in bone, long latency period or the general lack of knowledge concerning the possible relationship between Thorotrast and bone tumors. Statistical association between Thorotrast injection and bone sarcoma is shown. The criteria for the diagnosis of Thorotrastosis are discussed as well as the long term deleterious effects. The distribution of Thorotrast within the body is discussed as well as the associated radiographic changes.

Adult↗
PubMed1992

Endocytic pathways in the olfactory and vomeronasal epithelia of the mouse: ultrastructure and uptake of tracers.

Mammalian olfactory neurons possess a well-developed system of endocytic vesicles, endosomes, and lysosomes in their dendrites and perikarya. Vomeronasal neurons are similar and also contain much perikaryal agranular endoplasmic reticulum (AER). Olfactory supporting cells contain endocytic vesicles and endosomes associated closely with abundant fenestrated AER, and vesicles and numerous large dense vacuoles are present basally. Vomeronasal supporting cells have little AER, and few dense vacuoles occur in their bases. In olfactory neurons, ultrastructural tracers (0.08% horseradish peroxidase, thorium dioxide, ferritin) are endocytosed by olfactory receptor endings and transported to the cell body, where their movement is halted in lysosomes. Higher concentrations (1%) of horseradish peroxidase penetrate olfactory receptor plasma membranes and intercellular junctions. In olfactory supporting cells, endocytosed tracers pass through endosomes to accumulate in dense basal vacuoles. These observations indicate that olfactory sensory membranes are rapidly cycled and that endocytosed materials are trapped within the epithelium. It is proposed that in the olfactory epithelium, endocytosis presents redundant odorants to the enzymes of the supporting cell AER to prevent their accumulation, whereas in the vomeronasal epithelium the receptor cells carry out this activity.

Animals↗
PubMed1978

Long-term survival with thorotrast cervical granuloma.

Thorium dioxide, a radioactive contrast material, was commonly used for cerebral angiography prior to recognition of its radiation hazard. Extravasation of the material into the extravascular tissue in the neck results in granuloma formation, thorotrastoma, long-term morbidity, and an increased incidence of benign and malignant tumors. We report our experience with the management of 2 patients who underwent cerebral angiography with thorotrast more than 25 years ago. Aggressive surgical excision of involved tissue is warranted to ameliorate symptoms and diminish the risk of malignancy.

Adult↗
PubMed1995

Lack of apparent excess of malignant mesothelioma but increased overall malignancies of peritoneal cavity in Japanese autopsies with Thorotrast injection into blood vessels.

The carcinogenicity of thorium dioxide sol (Thorotrast), an X-ray contrast medium used in 1930-1955, in the liver and bone marrow has been established and agrees well with the effects of a high dosage of alpha radiation in the organs. Recently, however, German and Danish epidemiologic studies have shown excess mesotheliomas in the pleura and peritoneum that are unlikely to have been heavily irradiated by alpha particles. To confirm these observations, we examined the incidence of the cancer in those who underwent Thorotrast injections into blood vessels (n = 370) by using autopsy files of the Japanese Thorotrast study. Only one malignant mesothelioma of the peritoneum was registered, whereas three peritoneal or retroperitoneal sarcomas were observed. Thus, our study did not find any increment of mesothelioma in Thorotrast patients. However, when we took the pleuroperitoneal and retroperitoneal malignancies altogether, the incidence (4/370 = 1.1%) was five times more frequent than that (344/162,000 = 0.2%) in the controls (P < 0.005). Clinicopathological data of the four cases are also presented.

Adult↗
PubMed1985

Natural radioactivity in Indian tea.

The paper presents the results of measurements on tea samples collected during 1962 and 1973-1983 period for their natural radioactivity content. The radioisotopes studied under this programme are radium-226, thorium-228, and potassium-40. Tea was found to contain higher concentration of these radionuclides compared to other foodstuffs having vegetative origin. Interpretation for higher concentrations in tea compared to other foodstuffs is briefly given on the basis of agroclimatic conditions.

India↗