SEARCH · PubMed Health

Results for “MICROSCOPY, PHASE CONTRAST”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,243 records · Page 69Linked to original sources

PubMed1988

Streptozotocin toxicity to cultured pancreatic islets of the Syrian hamster.

Pancreatic islets of the Syrian golden hamster were maintained in culture for extended periods of time. Toxicity of streptozotocin in these cultures was evaluated by measurement of insulin secretion. Exposure of islets to 1 or 2 mM streptozotocin immediately following isolation resulted in a permanent and dose-related inhibition of insulin secretion. This was accompanied by islet disruption as observed by phase-contrast microscopy. Culture of islets for 24 hours before streptozotocin exposure afforded protection from toxicity. For example, exposure of freshly isolated islets to 2 mM streptozotocin resulted in complete destruction of beta cells, whereas islets similarly exposed after a 24 hr culture period continued to secrete insulin for many months. Islets maintained in culture for one week before exposure to 0.1-0.5 mM streptozotocin, however, became more sensitive than freshly isolated islets. Repeated weekly exposure of cultured islets to a "non-toxic" concentration (0.1 mM) resulted in sustained suppression of insulin secretion after 11 weeks.

Animals↗

PubMed1990

Histological evaluation of cochlear blood flow using different fixation methods.

For an accurate histological evaluation of cochlear blood flow, it is essential to fix the cochlear vessels while maintaining their physiological state. In the present study, we administered 10% CO2 to guinea pigs and then used phase-contrast microscopy to determine how two different methods of fixation influenced the cochlear vasculature. The first method of fixation employed perilymphatic perfusion in vivo, while the second one involved fixation after decapitation. Decapitation caused significant changes in the vessels of the stria vascularis, including constriction and sludging. In contrast, no sludging occurred in the perilymphatic perfusion method and erythrocyte morphology was preserved. However, dilatation of the strial blood vessels occurred after the inhalation of 10% CO2 even in the decapitation method. The results demonstrate that particular attention must be paid to the fixation method used, especially when evaluating the blood flow of the stria vascularis.

Animals↗

PubMed1996

Shear field mapping in actin networks by using magnetic tweezers.

An improved magnetic bead microrheometer based on phase contrast microscopy allowing high resolution measurements of local deformations within macromolecular network is applied to study local viscoelastic properties of cross-linked actin networks. By embedding nonmagnetic colloidal beads as probes into the networks, the spatial variation of the strain field within cross-linked actin networks can be mapped. Moreover, the Poisson ratio and shear modulus can be measured locally.

Actins↗

PubMed1976

Ultrastructural and cytochemical features of SV 40 transformed hypothalamic cell lines.

A continuous cell line was previously obtained by Simian Virus (SV) 40 transformation of primary cultures of dissociated mouse fetal hypothalami. One clone from this cell line has been previously shown to possess some of the ultrastructural features, immunological properties and synthesizing capacities of magnocellular hypothalamic neurons which secrete vasopressin and neurophysins. The present paper reports on the morphological characterization of 14 other clones or subclones of the original cell line, using the following criteria: phase contrast microscopy, electron microscopy, Gomori's aldehyde fuchsin staining, cytochemical detection of beta-glucuronidase, immunochemical staining with antisera against bovine neurophysin I, bovine neurophysin II, lys-vasopressin, oxytocin, LH-RH and TRH. The results allowed the conclusion that the clones as well as the subclones can be distributed into two groups: 1) neurosecretory neurons which all possess several of the ultrastructural and cytochemical features of the neurophysin-vasopressin synthesizing clone, and 2) primitive nerve cells which are devoid of such features but display numerous bundles of filaments. In addition some clones were found to display intermediate features between groups 1 and 2. A similar diversity was observed within clones of the original strain and subclones of a neurosecretory clone. It is suggested that the primitive clones could represent precursors of the neurosecretory clones.

Animals↗

PubMed1977

Distinction between smooth muscle, fibroblasts and endothelial cells in culture by the use of fluoresceinated antibodies against smooth muscle actin.

FITC-labelled antibodies against native actin from chicken gizzard smooth muscle (Gröschel-Stewart et al., 1976) have been used to stain cultures of guinea-pig vas deferens and taenia coli, rabbit thoracic aorta, rat ventricle and chick skeletal muscle. The I-band of myofibrils of cardiac muscle cells and skeletal muscle myotubes stains intensely. In isolated smooth muscle cells, the staining is located exclusively on long, straight, non-interrupted fibrils which almost fill the cell. Smooth muscle cells which have undergone morphological "dedifferentiation" to resemble fibroblasts with both phase-contrast microscopy and electronmicroscopy still stain intensely with the actin antibody. In those muscle cultures which contain some fibroblasts or endothelial cells, the non-muscle cells are not stained with the actin antibody even when the reactions are carried out at 37 degrees C for 1 h or after glycerination. Prefusion skeletal muscle myoblasts also do not stain with this antibody. It is concluded that the actin antibody described in this report is directed against a particular sequence of amino acids in muscle actin which is not homologous with non-muscle actin. The usefulness of this antibody in determining the origin of cells in certain pathological conditions such as atherosclerosis is discussed.

Actins↗

PubMed1989

Trypanosoma cruzi: involvement of proteolytic activity during cell fusion induced by epimastigote form.

Human erythrocytes were fused by Trypanosoma cruzi from 7 and 14 day old culture (stationary and declination phases, respectively) while only lysis was induced by 4 day old culture parasite (exponential phase). Lysis and erythrocyte fusion were studied by phase contrast microscopy, measuring of hemolysis and gel electrophoresis. The fusogenicity is Ca2+-dependent while lysis is delayed in the absence of exogenous Ca2+. The proteolysis of erythrocyte protein bands 1, 2, 2.1, 2.3 and 3 are common features of both fusion and lysis processes. Nevertheless the breakdown rate of ankyrin (band 2.1) and band 3 are different in fused or in lysed cells. The lysis process is associated with a faster degradation of band 2.1 and increase of band 2.3 than in the case of the fusion process. By contrast, degradation of band 3 occurs faster in the fusion than in the lytic event. Treatment of fusogenic parasites but not erythrocytes with TPCK, soybean trypsin inhibitor or FCS inhibited to some extent the fusion process and the decrease of bands 1, 2, 2.1, 2.3 and 3. The results suggest that proteases from fusogenic parasites may be directly or indirectly involved in the proteolysis of band 2.1 in a way related to induction of fusion.

Animals↗

PubMed1989

Cyclic AMP- and cytochalasin B-induced arborization in cultured aortic smooth muscle cells: its cytopharmacological characterization.

The present study analyzed effects of dibutyryl cyclic AMP (DB-cAMP) and cytochalasin B (CB) on the morphology of cultured aortic smooth muscle cells (SMC) from rat using phase-contrast microscopy, scanning electron microscopy, and fluorescence staining of actin filaments by the NBD-phallacidin method. The exposure of SMC to each of these agents led to rapid, extensive, and reversible (within 1-2 h of drug withdrawal) changes in their morphology including cytoplasmic arborization (stellation). The latter was preceded by (i) marginal membrane ruffles (DB-cAMP) and (ii) increased zeiotic activity (CB), which were visible within 20 min of the exposure, followed (30-90 min incubation) by a centripetal retraction of the cytoplasm and progressive development of complete or partial arborization. Further, the effects of substances interfering with the assembly-disassembly of microtubules (colchicine, taxol, lidocaine) on DB-cAMP- and CB-induced arborization were studied. None of these agents antagonized CB-induced morphological changes. Colchicine, but not lumicolchicine, taxol, or lidocaine (in a short-term study) prevented DB-cAMP-induced arborization. Taxol added to cell cultures for 24 h promoted DB-cAMP-induced arborization. Both DB-cAMP and CB resulted in the disintegration of actin filaments. The present data suggest that the arborization of cultured aortic SMC is a cytoskeleton-based process involving stabilization of microtubules and disintegration of actin filaments. Our study also suggests that the SMC arborization may represent an in vitro case of SMC stellation found in situ.

Actins↗

PubMed1988

Bone formation in vitro by stromal cells obtained from bone marrow of young adult rats.

Cells from fetal or neonatal skeleton can synthesize bone-like tissue in vitro. In contrast, formation of bone-like tissue in vitro by cells derived from adult animals has rarely been reported and has not been achieved using cells from bone marrow. We have explored development of bone-like tissue in vitro by bone marrow stromal cells. Marrow stromal cells obtained from 40-43-day-old Wistar rats were grown in primary culture for 7 days and then subcultured for 20-30 days. Cells were cultured in either alpha-minimal essential medium containing 15% fetal bovine serum, antibiotics, and 50 micrograms/ml ascorbic acid, or the above medium supplemented with either 10 mM Na-beta-glycerophosphate, 10(-8) M dexamethasone, or a combination of both. Cultures were examined using phase-contrast microscopy, undemineralized and demineralized tissue histology, histochemistry (for alkaline phosphatase activity), immunohistochemistry (for collagen type, osteonectin, and bone Gla-protein), scanning and transmission electron microscopy, energy dispersive X-ray microanalysis, and X-ray diffraction. Collagenous, mineralized nodules exhibiting morphological and ultrastructural characteristics similar to bone were formed in the cultures, but only in the presence of both beta-glycerophosphate and dexamethasone. Cells associated with the nodules exhibited alkaline phosphatase activity. The matrix of the nodules was composed predominantly of type-I collagen and both osteonectin and Gla-protein were present. X-ray microanalysis showed the presence of Ca and P, and X-ray diffraction indicated the mineral to be hydroxyapatite. The nodules were also examined for bone morphogenetic protein-like activity. Paired diffusion chambers containing partly demineralized nodules and fetal muscle were implanted intraperitonealy in rats. Induction of cartilage in relation to muscle was observed histologically after 40 days in the chambers. This finding provided further support for the bone-like nature of the nodules. The observations show that bone-like tissue can be synthesized in vitro by cells cultured from young-adult bone marrow, provided that the medium contains both beta-glycerophosphate and, particularly, dexamethasone.

Aging↗

PubMed1994

Electrically induced fusion of mammalian cells in the presence of polyethylene glycol.

Chinese Hamster Ovary (CHO) cells were fused by subjecting cell suspensions to an exponentially decaying electric pulse in the presence of polyethylene glycol (PEG), Dextran or Ficoll. PEG (MW 1,000, 3,350, 8,000, 10,000 and 18,500), Dextran (MW 71,200) and Ficoll (MW 400,000) were added to the pulsing medium. A single exponential electric pulse with peak field strength of 4 kV/cm, and a half-time of 0.72 msec was used. The combination of two techniques, PEG-induced fusion and electrofusion, resulted in highly efficient fusion of CHO cells. Fusion yields (FY) at different concentrations of these polymers were measured using phase-contrast microscopy. FY was highly dependent on the concentration of PEG in media, while the presence of Dextran and Ficoll had no influence on fusion yield. PEG with MW 8,000 was found to be the most effective in causing cell aggregation, and to give the highest FY (40%). An optimal concentration for fusion was found for PEG of each molecular weight. Diluting cells suspended in higher concentrations of PEG to these optimal concentrations after the pulse application regained the optimal FY. It was concluded that PEG-induced prepulse aggregation and moderate cell swelling immediately after the pulse were important factors in achieving high fusion yields.

Animals↗

PubMed1981

Cobalt filling of sensory projections from internal and external mouthparts in Drosophila.

Phase-contrast microscopy of 2.5 micron plastic sections reveals five different kinds of sense organs on the internal mouthparts of Drosophila melanogaster: a ventral group of sensilla on the epipharynx, three kinds of sense organs in the middle part of the sucking apparatus (the cibarium), one of them being described here for the first time, and an additional type of sensillum in the dorsal pharynx (Fig. 1). Three of these internal sense organs resembling each other structurally form similar projection patterns in the tritocerebrum, whereas external taste receptors on the labial palps show a different pattern in the suboesophageal ganglion (Fig. 12). The central projections of these internal and external sensilla were traced by applying an ethanolic solution of cobalt on the intact cuticle.

Animals↗

PubMed1987

The sequence of ultrastructural changes in cultured neurons after dendrite transection.

Cultured mouse spinal neurons were fixed at three different intervals after dendrite amputation: within the first 15 min, at 2 h and at 24 h. Dendrites were amputated at lesion distance of either 50 microns (31% probability of cell survival) or 100 microns (53% probability of cell survival) from the edge of their perikarya. When fixed within 15 min, operated neurons showed a two-phase gradient of ultrastructural damage which spread from the transection site towards the perikaryon. At 2 h after dendrite amputation all neurons operated close to their perikarya were categorized as either viable, moribund or dead, based on their appearance with phase contrast microscopy. These categories of response to physical trauma corresponded to distinctly different ultrastructural changes. Moribund neurons were filled with membrane-bound vesicles which were derived from swollen mitochondria and grossly dilated cisternae of the smooth endoplasmic reticulum. The cytoplasm of dead neurons contained large clear areas and many condensed, dark mitochondria. Both moribund and dead neurons lacked cytoskeletal elements. All of these ultrastructural changes are hypothesized to be the result of an increase in the intracellular concentrations of free calcium. Although evidence of residual mitochondrial swelling was present in some surviving neurons at 24 h, the ultrastructure of others was comparable to that of control cells. Some surviving neurons had terminal swellings at the ends of the severed neurites which were very similar to retraction balls of transected axons after CNS trauma.

Animals↗

PubMed1975

Prenatal diagnosis of I-cell disease.

A pregnancy from a family in risk of I-cell disease was monitored. The fetus was diagnosed as having I-cell disease based on the findings that (1) lysosomal enzyme activities except for acid phosphatase and alpha glucosidase were clearly elevated in amniotic fluid and were reduced in cultivated amniotic fluid cells, and (2) cytoplasmic inclusions were seen in cultivated amniotic cells by phase contrast microscopy. The accuracy of prediction was confirmed by cultured skin fibroblast of the aborted fetus.

Acid Phosphatase↗

PubMed1979

Nucleolar relationships in some Australian chironomus species.

Members of a group of Australian Chironomus species in the pseudothummi complex show wide variation in number and location of nucleolar organizing regions (NORs). The structure of these regions has been examined by phase contrast microscopy and silver banding of salivary gland polytene chromosomes. Presence of nucleoli was also checked on other types of chromosomes in some species. The contribution of the silver banding technique to nucleolar studies in these chironomid chromosomes is discussed. Nucleoli often seem to emerge from groups of (up to 9) bands. Further studies are necessary to confirm the presence of rRNA cistrons in all of these bands. Banding differences, in particular absence of bands from homologous regions of some species which have smaller nucleoli or lack particular nucleoli, have been found. In the case of Ch. tepperi, however, little banding difference is apparent in the 16B region between the N(IV)+ and N(IV)- chromosomes, although in situ hybridization (Eigenbrod 1978) shows a deletion of rRNA cistrons in the N(IV)- stock. Differences in heterochromatin amount have also been observed at different NORs. A scheme for the evolution of nucleolar-producing regions in this Chironomus group in terms of these and other known chromosomal changes is presented and discussed.

Animals↗

PubMed1980

Isolation of hepatocytes from newborn rats.

A method is described for the preparation of isolated hepatocytes from 5 day old rats, based on the procedure of Berry and Friend (1969). In contrast to the original procedure the liver of newborn rats was perfused in the reverse direction from the vena cava caudalis (pars thoracalis) to the vena portae. The cells obtained by the above method are morphologically intact as shown by electron micrographs and by phase contrast microscopy. About 85% of the isolated cells exclused trypan blue. Neonatal liver cell preparations were used for dose response studies with phallotoxins and further experimental applications in the field of phalloidin tolerance of newborns are described.

Animals↗

PubMed1990

High endocytotic and lysosomal activities in segments of rat myotubes differentiated in vitro.

Endocytosis and the lysosome system have been studied in rat myotubes differentiated in vitro. Horseradish peroxidase was used as marker for endocytosis and was found to accumulate unevenly in the myotubes. Small segments of myotubes display very high endocytotic activity. Similar segments contained numerous lysosomes, as seen by the accumulation of neutral red or histochemical staining for acid phosphatase. The segments also contained accumulations of acetylcholine receptors as determined by binding of tetramethyl rhodamine-labelled alpha-bungarotoxin. Unstained segments in living cultures could be recognized by phase-contrast microscopy since they often appeared somewhat dilated and were not as well spread on the culture surface as the main parts of the myotubes. Ultrastructurally, the segments contained an intensely proliferating tubular system in communication with the extracellular space, which therefore probably represents the developing transverse tubular system. The segments also contained endocytosed marker within large phagosomes. Contractile filaments occurred in the segments but were frequently less well-organized than in other parts of the myotubes. The described characteristics of the segments in rat myotubes differentiated in vitro bear resemblance to some of the characteristics of the denervated endplate region of adult muscle.

Animals↗

PubMed1988

Cytotoxicity of acrylamide and related compounds to mouse neuroblastoma and rat schwannoma cells.

Cytotoxicity of acrylamide and related compounds to mouse neuroblastoma N18TG-2 and rat Schwannoma RT4 cells was studied. Of nine test chemicals, acrylamide and N-hydroxymethylacrylamide were most toxic compared with others on the basis of ED50 value. Observation under phase-contrast microscopy revealed that in N18TG-2 acrylamide produced both degeneration of the cells and inhibition of cell growth, and that in RT4 it produced only inhibition of cell growth without causing any marked morphological changes. Dibutyryl cyclic AMP (dBcAMP) reduced the cytotoxicity of acrylamide to both types of cells on the basis of the dose-effect curve. Studies on the subcellular distribution of 14C-acrylamide incorporated showed that more than 90% of the total radioactivity was incorporated in the 15,000 g supernant fraction. Kinetics of acrylamide uptake by N18TG-2 cells showed that in the cells untreated with dBcAMP there were two binding sites with high and low affinity, and that after treatment with dBcAMP the site of high affinity disappeared. The situation was true for RT4 cells, the results indicating that the immature cells are more vulnerable to acrylamide than the mature cells.

Acrylamides↗

PubMed1991

Methods for improving tissue culture of human tracheo-bronchial epithelium obtained at autopsy.

Human tracheo-bronchial epithelium obtained from autopsy, surgery, and organ donation will have areas of both viable and non-viable cells. It is important in the initial establishment of epithelial explant and cell cultures that injured, non-viable mucosal epithelium not be used for the cultures. Autopsy cases selected for culture should initially be chosen on the basis of a shorter post mortem interval and cause of death in order to increase the rate of successful culture. Staining the epithelium with the vital dye, trypan blue, in combination with phase contrast microscopy of the bronchial tissues will further identify those areas of the mucosa that are enriched for viable cells. The dead, non-viable areas are trypan blue positive, while the viable areas are clear and have foci of beating, motile cilia. Treatment of the mucosal tissue with mucolytic agents to remove cell debris, dead cells, and microbes trapped in the mucus material will further improve the chances for successful culture. Human tracheo-bronchial epithelium, although non-sterile and often injured at time zero for numerous reasons, can effectively be used in vitro pathophysiology studies.

Aryl Hydrocarbon Hydroxylases↗

PubMed1995

Establishment and characterization of a new cell line from human bladder cancer (JMSU1).

A new human bladder cancer cell line designated JMSU1 has been established from malignant ascitic fluid of a 75-year-old Japanese man with bladder cancer, and maintained in culture for more than 7 years and over 240 passages. Inverted phase-contrast microscopy revealed that JMSU1 was composed of morphologically distinct cells (polygonal to spindle-shaped cells), showing morphological heterogeneity in vitro. Histological examination of xenografts showed poorly differentiated transitional cell carcinoma, resembling the original tumor. Immunohistochemical staining for cytokeratin and electron microscopic examination suggested that JMSU1 was of epithelial origin. Chromosome analysis gave a modal number of 69 with no Y chromosome. Isozyme analysis (LDH, G6PD, and NP) showed the mobility pattern of human type B. DNA fingerprint analysis demonstrated that there was no cross-culture contamination of JMSU1 during the passages. In conclusion, a newly established and well-characterized cell line, JMSU1, offers promising material for the investigation of the biological properties of bladder cancer.

Aged↗