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Biomedical subjects

K E Tvedt

Publications and source records attributed to K E Tvedt.

15 recordsLinked to original sources
PubMed1992

Cellular differentiation in prostatic explant cultures: assessed by electron microscopy and X-ray microanalysis.

A method developed for X-ray microanalysis (XRMA) of cell monolayers cultured on Formvar film has been shown to be well suited for the study of explant cultures of human prostate. Adherence and epithelial cell outgrowth occur as readily on the formvar as on ordinary tissue culture plastic, giving rise to cultures with the same morphological characteristics. Conventional transmission electron microscopy revealed intracytoplasmic granules with the appearance of secretory vesicles. XRMA of electron-dense intracytoplasmic granules in freeze-dried cryosections showed significant local sequestration of calcium, but not of magnesium or zinc, elements that have previously been shown to colocalize with calcium in secretory granules in vivo. It is concluded that some aspects of the secretory phenotype are supported in this in vitro model. The factors regulating the expression of a differentiated phenotype in prostatic epithelium await further elucidation. XRMA may be useful in assessing the effects on secretory differentiation induced by variations in the culture conditions.

Biopsy↗
PubMed1990

Intracellular penetration and accumulation of radiographic contrast media in the rat kidney.

Radiographic iodine-containing contrast media (meglumine calcium metrizoate, iohexol and meglumine sodium ioxaglate) were injected intravenously in rats. At various intervals after exposure, in situ cryofixation of kidneys was performed. Thin, freeze-dried cryosections were examined by electron microscopy and X-ray microanalysis. In endothelial cells, erythrocytes and tubular cells high dry weight concentrations of iodine were found. Twenty-four hours after iohexol was injected, no trace of iodine was found in the plasma, microvilli or the nuclei of the tubular cells. Small organelle-like compartments in the cytoplasm of the proximal tubular cells contained high concentrations of iodine, whereas no iodine was found in the surrounding cytoplasm. Since no metabolism of contrast medium has been demonstrated, the iodine signals must be emitted from contrast medium molecules. Other elements were also measured, with the concentrations being always within the ranges found in tubular cells of control animals. The detection of intracellular contrast thus does not seem to be an artifact due to cell injury, but rather represents a physiological event in healthy cells in the rat kidney. Our results are in contradiction to the prevailing opinion that contrast media do not enter healthy cells. However, previous conclusions have been based on the use of conventional preparation methods, and the highly water soluble contrast molecules may have been lost during the different steps of fixation and processing.

Animals↗
PubMed1989

Intracellular distribution of calcium and zinc in normal, hyperplastic, and neoplastic human prostate: X-ray microanalysis of freeze-dried cryosections.

X-ray microanalysis has been performed on freeze-dried cryosections of normal, hyperplastic, and neoplastic human prostates. Needle biopsies from prostates suspected to be malignant were collected from ten patients. Seven of these patients had fully developed nodular hyperplasia, whereas the remaining three specimens were histologically classified as moderately differentiated adenocarcinomas. Prostates with normal light microscopic appearance were obtained from two brain-dead kidney donors. The concentration of calcium in secretory vesicles was found to be several orders of magnitude higher than the concentration of magnesium and zinc in all of the glands studied, which is consistent with calcium being the major cation secreted by the prostatic acinar cells. Some elderly prostates and neoplastic prostates revealed even lower mean zinc:calcium ratios in secretory vesicles. Even though both elements varied considerably, the wide variation of the zinc:calcium ratios was due mainly to variations in the concentration of zinc. Large, electron-dense bodies occasionally were found in the cytoplasm of prostatic acinar cells. These bodies contained high concentrations of sulphur which by far was the dominating element.

Adult↗
PubMed1989

Rapid freezing of small biopsies and standard for cryosectioning and X-ray microanalysis.

A method for clamp-freezing of small biopsies for ultrathin cryosectioning is described. A formvar film is used to support the specimen before freezing with a pair of pliers, precooled in liquid nitrogen. This method makes it possible to align the piece of tissue close to a drop of standard solution and freeze the two simultaneously. After clamping, the flat, frozen sample contains both the piece of tissue and the standard in one solid block, which may thus be sectioned as a whole. The method has been used in the surgical theater, yielding good results with needle biopsies of the prostate and cystoscopically obtained biopsies of bladder tumors. The time lapse between excision and freezing may be less than 30 seconds, which represents a great improvement compared with the far more time-consuming mincing of tissue and mounting of the pieces on metal pins. From the frozen specimen, a large number of sections with good morphologic characteristics may be produced. The method was evaluated with the use of rat liver and lactating mammary tissue. Directly frozen tissue with intact blood supply was compared with biopsies prepared as described. Redistribution of Ca could not be demonstrated in either specimen type. However, the results indicate that the monovalent ions are far more mobile, and a significant increase of the Na:K ratios was observed in the biopsies compared with directly frozen tissue.

Animals↗
PubMed1989

Incorporation of contrast media in cultured cells.

Monolayer cultures of human prostatic (PC-3) and cervical (NHIK 3025) carcinoma cells were grown on formvar film and exposed to moderate concentrations of contrast agents for 30 minutes to 4 hours. After the exposure period, the monolayers were quickly frozen, and cryosections were examined by electron microscopy and X-ray microanalysis. Iodine was not detected in control cells, but was found in the cells that had been exposed to iodine-containing contrast media. The amount of intracellular iodine increased with increasing exposure dose and time. Because the cells mostly presented no sign of membrane damage, our findings support the view that contrast media have the ability to enter intact cells.

Cell Nucleus↗
PubMed1988

Quick sampling and perpendicular cryosectioning of cell monolayers for the X-ray microanalysis of diffusible elements.

A quick sampling and preparation method for freezing of cell monolayers is described. The cells are grown on a large Formvar film supported by a frame of polystyrene. A polyvinylpyrrolidone (PVP) solution is applied to one side of the film forming a flat disc when frozen with a pair of pliers precooled in liquid nitrogen. The PVP solution provides the specimen with sufficient strength and may be used as an elemental standard for absolute quantification if salts of known concentrations are added. Manipulation of the cells prior to freezing is thus restricted to a minimum, which eliminates possible harmful treatments like scraping and centrifugation. The procedure is quickly performed, the freezing being completed within 30 s of the cells having been removed from the culture well. The analytical results reveal low and stable Na:K ratios. Our results confirm that cells in vitro are comparable to cells in vivo with respect to elemental composition.

Adenocarcinoma↗
PubMed1987

Subcellular concentrations of calcium, zinc, and magnesium in benign nodular hyperplasia of the human prostate: X-ray microanalysis of freeze-dried cryosections.

Biopsies from human prostates were obtained from normal and hyperplastic glands. The intracellular concentrations of calcium, zinc, and magnesium were analyzed using X-ray microanalysis of freeze-dried cryosections. Two prostate biopsies were obtained from kidney donors, ages 19 and 50 years, without any sign of benign nodular hyperplasia. The normal tissues were frozen within 15 min after circulatory arrest. The central part of biopsies from eight elderly men suffering from benign nodular hyperplasia were frozen within 30 s after excision. Adjacent tissue was processed for light microscopy and histopathological diagnosis. All samples were fresh-frozen using liquid nitrogen cooled pliers, without the use of any freeze-protection, fixation, or staining. In both the normal and the hyperplastic prostates high concentrations (up to above 100 mmol/kg dry weight) of zinc were present in electron dense bodies in the cytoplasm of the epithelial cells. Together with zinc, about equal concentrations of magnesium were found. Calcium was detected in 4 to 8 times the concentration of zinc. Significant, positive correlation between calcium and zinc as well as between calcium and magnesium in the cytoplasm was a typical finding in both normal and hyperplastic glands. In six of eight patients, older than 60 years of age, high levels of calcium (17.0-38.8 mmol/kg dry weight) were observed in the nuclei of the epithelial cells, while very low values were found in the remaining two. In the two younger cases (19 and 50 years of age), the nuclear calcium level in prostatic epithelium was relatively low (about 10 mmol/kg dry weight). These observations suggest that an increase of intranuclear calcium with advancing age may be of pathogenetic significance to growth disturbances in the prostate.

Adult↗
PubMed1985

Idiopathic haemochromatosis and eye symptoms. A case report.

A 61-year-old man with idiopathic haemochromatosis and eye symptoms is described. The examination showed microaneurysms scattered over the bulbar conjunctiva, and some discrete pigmentations in the superficial tissue in the perilimbal area. Each cornea revealed a light brown, ellipsoid opacity with the longest diameter horizontally, seemingly being located in the corneal epithelium and/or the anterior part of the stroma. A corneal biopsy was examined by light and electron microscopy. Two different types of granules were found mainly located to the Bowman's membrane. X-ray microanalysis showed no detectable amounts of iron, but high concentrations of phosphorus and calcium, and in addition magnesium in one type of the granules. Treatment with EDTA improved the vision considerably.

Conjunctiva↗
PubMed1984

A section press and low elemental support for enhanced preparation of freeze-dried cryosections.

A press- and specimen holder system is described, whereby thin, freeze-dried cryosections can be obtained more conveniently and with greater protection against contamination and harmful temperature fluctuations. The use of a grid and retainer assembly as the basic working unit, greatly facilitates low temperature work particularly when delicate grids are preferable from an analytical point of view. A new press has been constructed in order to keep the sections permanently pressed during freeze-drying and rewarming. The press also protects the sections during transfer to an external freeze-dryer.

Animals↗
PubMedDate not supplied

The c-erbB-2 protein in primary and metastatic breast carcinomas.

Material from 41 patients with primary breast carcinoma and lymph node metastases at the time of primary surgical intervention was immunostained for c-erbB-2 protein, neuron-specific enolase (NSE), and estrogen receptors. Thirty of the primary breast carcinomas were of ductal type. Six were classified as infiltrating lobular carcinomas, 2 were apocrine, 1 was mucinous, and 1 was a tubular carcinoma. One tumor could not be classified as ductal or lobular by light microscopic examination alone. The number of lymph node metastases available varied from 1 to 14 per case (median, 3.9). Nine (22%) of the primary breast carcinomas (8 ductal and 1 apocrine) expressed c-erbB-2 protein and showed c-erbB-2 gene amplification; 12 expressed NSE immunoreactivity. None expressed both markers. Estrogen receptor immunoreactivity was present in 23 of the 41 cases, including 9 of the NSE-positive cases. C-erbB2- protein-positive metastases were present in 18 cases (44%), and in 13 cases all metastases were immunostained. In 5 cases the expression of c-erbB-2 protein varied from metastasis to metastasis. NSE immunoreactivity was expressed in 10 cases, and in 3 cases with minor NSE-positive cell populations the metastatic lesions expressed c-erbB-2 protein as well. All 9 primary breast carcinomas expressing c-erbB-2 protein had lymph node metastases with c-erbB-2-immunoreactive tumor cells. Eight of the 9 c-erbB-2 protein-negative primary tumors with metastases expressing c-erbB-2 protein showed no amplification of the c-erbB-2 gene.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗