Closely related colon cancer cell lines display different sensitivity to polyunsaturated fatty acids, accumulate different lipid classes and downregulate sterol regulatory element-binding protein 1

N-6 polyunsaturated fatty acids (PUFAs) may be associated with increased risk of colon cancer, whereas n-3 PUFAs may have a protective effect. We examined the effects of docosahexaenoic acid (DHA), eicosapentaenoic acid and arachidonic acid on the colon carcinoma cell lines SW480 derived from a primary tumour, and SW620 derived from a metastasis of the same tumour. DHA had the strongest growth-inhibitory effect on both cell lines. SW620 was relatively more growth-inhibited than SW480, but SW620 also had the highest growth rate in the absence of PUFAs. Flow cytometry revealed an increase in the fraction of cells in the G2/M phase of the cell cycle, particularly for SW620 cells. Growth inhibition was apparently not caused by increased lipid peroxidation, reduced glutathione or low activity of glutathione peroxidase. Transmission electron microscopy revealed formation of cytoplasmic lipid droplets after DHA treatment. In SW620 cells an eightfold increase in total cholesteryl esters and a 190-fold increase in DHA-containing cholesteryl esters were observed after DHA treatment. In contrast, SW480 cells accumulated DHA-enriched triglycerides. Arachidonic acid accumulated in a similar manner, whereas the nontoxic oleic acid was mainly incorporated in triglycerides in both cell lines. Interestingly, nuclear sterol regulatory element-binding protein 1 (nSREBP1), recently associated with cell growth regulation, was downregulated after DHA treatment in both cell lines. Our results demonstrate cell-specific mechanisms for the processing and storage of cytotoxic PUFAs in closely related cell lines, and suggest downregulation of nSREBP1 as a possible contributor to the growth inhibitory effect of DHA.

Gut luminal microdialysis of glycerol as a marker of intestinal ischemic injury and recovery

OBJECTIVE

To evaluate microdialysis as a method to assess different degrees of intestinal damage and recovery during ischemia and reperfusion; to evaluate information obtained from microdialysis catheters in the peritoneum, the gut wall, and the gut lumen.

DESIGN

Randomized, controlled animal experiment.

SETTING

University laboratory animal center.

SUBJECTS

Twenty-seven domestic pigs.

INTERVENTIONS

The superior mesenteric artery was cross-clamped for 60 mins (n = 14) or 120 mins (n = 10) followed by 2 or 4 hrs of reperfusion. Three pigs served as controls.

MEASUREMENTS AND MAIN RESULTS

Intestinal mucosal integrity was assessed by morphometry, adenosine triphosphate in the gut wall, and permeability of C-polyethylene glycol. Lactate, glycerol, pyruvate, and glucose were measured by microdialysis. Changes in adenosine triphosphate, permeability, or lactate did not correlate to different extents of intestinal damage caused by 60 or 120 mins of ischemia. During the reperfusion period, pigs with 60 mins of intestinal ischemia showed a faster recovery of these variables than pigs with 120 mins of intestinal ischemia. Glycerol increased with increasing duration of the ischemic insult. After 60 mins of intestinal ischemia, glycerol in the gut lumen decreased toward baseline but remained high after 120 mins of intestinal ischemia. There was a good correlation between gut luminal glycerol and recovery of mucosal damage throughout the reperfusion period. In the peritoneal cavity, both glycerol and lactate decreased to baseline relatively shortly after onset of reperfusion independent of the duration of intestinal ischemia.

CONCLUSIONS

Microdialysis of glycerol provides information about the extent and severity of intestinal damage after ischemia and about the ensuing recovery. The gut lumen is to be preferred as a site for placement of microdialysis catheters.

Intestinal injury after thoracic aortic cross-clamping in the pig

BACKGROUND

The mucosal surface epithelium is an essential part of the functional intestinal barrier, but its structural response to ischemia/reperfusion is only partly characterized. The purpose of this study was to provide a detailed morphological evaluation of intestinal surface epithelium after aortic cross-clamping.

MATERIAL AND METHODS

Pigs were subjected to thoracic aortic cross-clamping for 60 min and subsequent reperfusion for 120 min. Tissue blood flow and high-energy phosphates were measured with microspheres and HPLC, respectively. Urinary excretion of (14)C polyethylene glycol (MW 4000 Da) (PEG-4000), loaded into an intestinal loop, provided an index of intestinal permeability.

RESULTS

Jejunal blood flow was restored at 10 min after aortic declamping. Denudation of the basement membrane of the intestinal villi tips, as a consequence of epithelial shedding, increased markedly during the initial 60 min of reperfusion (P = 0.002). During the following 45 min, the denuded basement membrane was partly covered with low cuboidal and squamous-shaped cells extending lamellipodia over a wavy basement membrane. Restoration of ATP at 60 min after aortic declamping correlated inversely to the extent of denuded basement membrane (r = 0.75, P = 0.032). Permeability of PEG-4000 increased markedly after aortic declamping and was linearly correlated to the area of denuded basement membrane (r = 0.87, P = 0.01).

CONCLUSIONS

Reperfusion for 2 h after aortic cross-clamping is associated with initial aggravation of ischemia-induced injury in the porcine jejunum, but thereafter with restitution of the surface epithelium. Restoration of ATP may be important to avoid intestinal injury after ischemia. Increased permeability of a macromolecule in response to reperfusion is closely correlated to injury of the surface epithelium.

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.

In vivo MRI of olfactory ensheathing cell grafts and regenerating axons in transplant mediated repair of the adult rat optic nerve

The purpose of the present study was to use magnetic resonance imaging (MRI) as a tool for monitoring transplant-mediated repair of the adult rat visual pathway. We labelled rat olfactory ensheathing cells (OECs) using micron-sized particles of iron oxide (MPIO) and transplanted them by: i) intravitreal injection (ivit) and ii) intra-optic nerve (ON) injection (iON) in adult rats with ON crush (ONC) injury. We applied T(2)-weighted MRI and manganese-enhanced MRI (MEMRI) to visualise transplanted cells and ON axons at specific times after injury and cell engraftment. Our findings demonstrate that ivit MPIO-labelled OECs are unequivocally detected by T(2)-weighted MRI in vivo and that the T(1)-weighted 3D FLASH sequence applied for MEMRI facilitates simultaneous visualisation of Mn(2+-) enhanced regenerating retinal ganglion cell (RGC) axons and MPIO-labelled OEC grafts. Furthermore, analysis of MRI data and ultrastructural findings supports the hypothesis that iON OEC transplants mediate regeneration and remyelination of RGC axons post injury.

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.

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)

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.

Transepithelial transport of morphine and mannitol in Caco-2 cells: the influence of chitosans of different molecular weights and degrees of acetylation

The object of this study was to compare the effect of chitosans of different number-average molecular weights (MWs) and degrees of acetylation (FA) on transepithelial transport of morphine in Caco-2 cells. Caco-2 monolayers on polycarbonate (PC) membranes (0.5cm2) were incubated with morphine (10μ) or mannitol (55μ) for 180 min. Samples for analysis of morphine (LCMSMS) and mannitol (liquid scintillation) were drawn at 45, 90, 120 and 180 min. Transepithelial electrical resistance (TEER) and transmission electron microscopy were used to monitor cell integrity. In controls, morphine transport was half that of mannitol. Chitosans affected the transport of morphine and mannitol similarly. For chitosans with similar FA (0.32-0.43) and varying MWs (7–200 kD), transport was increased at MWs of 29 kD or more. Among chitosans of similar MWs (180–300 kD) and varying FA (0.01-0.61), those with the highest Fa (0.61) had the least effect, while chitosans with Fa/MW 0.01/250 and 0.17/300 promoted the greatest transport. An FA/MW of 0.32/200 and 0.43/170 induced a high and stable transport rate. Chitosans may enhance transepithelial transport of morphine by the same mechanism as for mannitol. Chitosans with FA of 0.3-0.4 and MW of approx. 200 kD seem favourable in this respect.

Labelling of olfactory ensheathing cells with micron-sized particles of iron oxide and detection by MRI

A crucial issue in transplant-mediated repair of the damaged central nervous system (CNS) is serial non-invasive imaging of the transplanted cells, which has led to interest in the application of magnetic resonance imaging (MRI) combined with designated intracellular magnetic labels for cell tracking. Micron-sized particles of iron oxide (MPIO) have been successfully used to track cells by MRI, yet there is relatively little known about either their suitability for efficient labelling of specific cell types, or their effects on cell viability. The purpose of this study was to develop a suitable MPIO labelling protocol for olfactory ensheathing cells (OECs), a type of glia used to promote the regeneration of CNS axons after transplantation into the injured CNS. Here, we demonstrate an OEC labelling efficiency of >90% with an MPIO incubation time as short as 6 h, enabling intracellular particle uptake for single-cell detection by MRI without affecting cell proliferation, migration and viability. Moreover, MPIO are resolvable in OECs transplanted into the vitreous body of adult rat eyes, providing the first detailed protocol for efficient and safe MPIO labelling of OECs for non-invasive MRI tracking of transplanted OECs in real time for use in studies of CNS repair and axon regeneration.

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.

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.

CDw75 antigen expression in breast lesions

Alterations on the cell surface of the oligosaccharide portion of glycoproteins and glycolipids are thought to play a role in tumorigenesis. Sialyltransferase catalyzes the incorporation of sialic acid to the carbohydrate group of glycoconjugates. Sialyltransferase has been found elevated in different tumour tissues and in the serum of cancer patients. In the present study we have examined the expression of the beta-galactosyl alpha 2,6-sialyltransferase requiring epitope CDw75, with the monoclonal antibody HH2. 142 breast lesions were included. 21% of the carcinomas in situ and 35% of the invasive carcinomas showed a diffuse cytoplasmic staining. Seven cases of invasive carcinomas also showed a distinct membrane immunoreactivity. We found no correlation between reactivity for CDw75 in malignant lesions and their metastatic potential. Only five out of 11 primary tumours with metastases expressed CDw75 in the primary tumour. In the benign lesions, there was a positive reaction in proliferating lesions, e.g. intraductal papillomas (2 out of 3 cases) and in epithelial proliferations in fibrocystic disease (10 out of 14 cases). None of the four fibroadenomas and phyllodes tumours and only one out of 22 cases of normal breast tissues showed immunoreactivity for HH2. In the malignant lesions, CDw75 was more frequently expressed in the carcinomas of high malignancy grade. The high frequency of immunoreactivity among the benign breast lesions can be indicative of activation of the epithelial cells.

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.

Post-ischaemic restituted intestinal mucosa is more resistant to further ischaemia than normal mucosa in the pig

OBJECTIVE

Ischaemic preconditioning may protect the intestine from subsequent prolonged ischaemia. This study evaluates whether a much longer initial ischaemia, encountered clinically, may modify intestinal resistance to further ischaemia in a pig model.

MATERIAL AND METHODS

After cross-clamping of the superior mesenteric artery for 1 h, the intestine was either reperfused for 8 h or a second cross-clamping for 1 h was performed at 4 h of reperfusion. Based on microarray analysis of intestinal samples at 1, 4 and 8 h of reperfusion, mRNA of selected genes was measured with QRT-PCR.

RESULTS

The first ischaemic period caused exfoliation of surface epithelial cells from the basement membrane comprising about 90 % of the villi tips, a marked increase in permeability and depletion of ATP. The second ischaemic challenge caused about 30 % less denudation of the basement membrane (p = 0.008), no increase in permeability (p = 0.008) and less depletion of ATP (p = 0.039). mRNAs for superoxide dismutase 2, heat shock proteins and signal transducer and activator of transcription 3, which may protect against ischaemia/reperfusion injury, were up-regulated throughout the reperfusion period. mRNAs for matrix metalloproteinase 1, connexin 43 and peripheral myelin 22, which may be associated with cell migration or tight junctions, showed a particular up-regulation at 4 h of reperfusion.

CONCLUSION

One hour of initial ischaemia followed by 4 h of reperfusion is associated with increased intestinal resistance to further ischaemia. The differential regulation of genes identified in this study provides working hypotheses for mechanisms behind this observation.

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.

Contrast medium concentration in epithelial mucosal cells after colonic instillation of lodixanol: a semiquantitative study indicating the route of permeation

RATIONALE AND OBJECTIVES

Studies have shown that water-soluble radiographic contrast media may be useful as intestinal permeability probes. The current study was undertaken to provide information about the route by which such a permeability probe crosses the mucosal epithelium.

MATERIALS AND METHODS

The authors administered 3 mL of iodixanol (iodine, 320 mg/mL) by means of an enema into the colons of (a) rats with experimental colitis induced 14 days earlier and (b) normal rats. At various intervals after the enema, laparotomy was performed and the colon was identified and longitudinally split immediately before cryofixation, without prior interruption of circulation. Freeze-dried cryosections were studied by means of electron microscopy and x-ray microanalysis.

RESULTS

Approximately equal concentrations of iodine were found intracellularly and between the epithelial cells of the colonic mucosa. Ninety percent of analyzed cells had a normal sodium-potassium ratio and low levels of intracellular chlorine, indicating intact cell membranes. Nevertheless, many of these cells, in specimens from both normal rats and rats with colitis, contained high intracellular iodine concentrations.

CONCLUSION

The transcellular route seems to be at least as important as the paracellular route for permeation of the highly water-soluble molecule iodixanol through the mucosal epithelium of both normal and inflamed rat colon. This finding may contradict previous findings in other water-soluble substances.

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.

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.