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Query: UMLS:C0009443 (cold)
 92,137 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An electron microscopic immunohistochemical localization of thyroglobulin (TG) using PAP methods has been made in 15 cases of cold follicular adenoma. All cases of follicular adenoma showed organ specific functions such as synthesis, storage, reabsorption, and hydrolysis of thyroglobulin except for an area composed of follicular cells with trabecular arrangement. Immuno-reaction product for TG was precisely demonstrated in follicular lumina, subapical vesicles and reabsorbed colloid droplets. The reaction product observed in the follicular lumen was clearly demarcated from the cytoplasm of the follicular cells by the apical plasma membrane. The subapical vesicles ranging approximately from 50 millimicrons to 300 millimicrons in diameter were rarely observed in follicular adenoma and some of them fused with the reabsorbed colloid droplets. The reabsorbed colloid droplets usually had the intense reaction product and hydrolyzed colloid droplets had a vacuole containing floccular low electron dense materials. There is no reaction product in rough endoplasmic reticulum and Golgi complexes.
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PMID:Immunoelectron microscopic localization of thyroglobulin in human follicular adenoma. 636 52

We have devised a method for the isolation of viable neuronal growth cones from neonatal rat forebrain. The method involves differential and density gradient centrifugation and exploits the relatively low buoyant density (approximately 1.018 g/cm3) of growth cones. There are no known biochemical markers for growth cones and it was necessary therefore to monitor for their presence during the isolation using transmission electron microscopy. Several criteria were used to identify isolated growth cones including the presence of filopodia, an extensive system of branching, tubular smooth endoplasmic reticulum and a region rich in microfilaments subjacent to the plasma membrane. These morphological features are similar to those of growth cones identified unequivocally in intact developing brain and in tissue culture. Electron microscopical analysis showed that greater than 90% of membrane-bound, identifiable objects in one fraction were growth cones by these criteria. The major contaminant consisted of membrane sacs and vesicles of unidentified origin. There were only small amounts of isolated rough endoplasmic reticulum and mitochondria. Isolated growth cones were roughly spherical in shape with a diameter of 1.9 +/- 0.5 micron (mean +/- 1 SD). They usually contained mitochondria, large granular vesicles and small vesicles, and occasionally contained coated vesicles, lysosomes, lamellar bodies and multivesicular bodies, and only very rarely, intermediate filaments. Occasionally, growth cones had rudimentary synapses on them. The viability of isolated growth cones was investigated by observing their behaviour in short-term culture. After a few hours in culture on poly-D-lysine-coated coverslips, growth cones flattened down and extended filopodia-like processes. This behaviour was inhibited by cytochalasin B and reversibly by cold (4 degrees C). We conclude that physiologically active growth cones can be isolated rapidly and in large numbers by the method described here.
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PMID:Isolation and partial characterisation of neuronal growth cones from neonatal rat forebrain. 649 82

Depending on the pre-experimental treatment, densities as well as sizes of particles associated with the visual membranes in the eyes of Procambarus clarkii varied. The highest mean particle density (5268 +/- 969 microns -2) and the smallest mean particle diameter (5.57 +/- 1.35 nm) were found in crayfish which had been kept in the dark for 10 weeks in aerated fresh water of 10 degrees C. Crayfish kept under a 12 h dark/light regime in water of 10 degrees C or 30 degrees C for three weeks displayed particle densities of 1076 +/- 180 and 2899 +/- 249 microns -2, respectively; particle diameters were of the order of 8 nm. Temperature did not alter the shape or the slope of the V/log I curves, but ERG recordings show that maximum spectral sensitivity was shifted from lambda max = 560 nm in cold water crayfish (10 degrees C) to lambda max = 580 nm in crayfish from the 30 degrees C tank, and that the 10 degrees C curve was somewhat narrower than the 30 degrees C curve. It is suggested that the observed shift was caused by a combination of factors, of which the following may have played key roles: (1) The filter effect of screening pigment granules and other intracellular components such as vesicles, vacuoles, endoplasmic reticulum, and mitochondria, some of which were developed to a considerably greater extent in 30 degrees C material; (2) increased membrane fluidity due to higher temperature as well as the presence of photoproducts in the light, and the 'countermeasures' taken by the visual pigment molecules to stabilize the lipid bilayer, e.g. higher density, possible 12-s-cis linkages etc.; and (3) increased regeneration or synthesis of rhodopsin due to higher metabolic activity of retinula cells at higher temperatures. Temperature-induced changes of visual pigments in a variety of organisms are discussed and evidence for the rhodopsin-aggregate model of crayfish visual pigment is presented. It is concluded that the retinula cytoplasm is involved in restoring depleted stocks of photopigment, and that the biological sense of possessing an increase in red sensitivity during the warm summer months lies in the correlation of light penetration in the natural habitat of P. clarkii and optimal exploitation of the habitat.
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PMID:The effects of temperature and light on particles associated with crayfish visual membrane: a freeze-fracture analysis and electrophysiological study. 653 77

The synthesis of functional AChRs can be described as a pathway leading from the translation of subunit mRNAs to the plasma membrane forms of extrajunctional and junctional receptors (Fig. 9). We have not included in this scheme pretranslational steps for the synthesis and processing of RNA coding for receptor subunits because very little is known about such processes. Several aspects of Figure 9 are worthy of note: It is now well established that polypeptide synthesis is initiated on free cytoplasmic polysomes and that once sufficient nascent subunits bearing signal peptides at the amino terminus is formed, polysomes assemble with the membranes of the rough endoplasmic reticulum via a mechanism that employs the signal recognition particle (Anderson et al. 1982). Nascent subunits undergo cotranslational insertion through the rough endoplasmic reticulum membrane, signal peptide removal, and core glycosylation (Anderson and Blobel 1981; Merlie et al. 1981; Anderson et al. 1982; Sebbane et al. 1983). Anderson and Blobel (this volume) have demonstrated that subunits synthesized in vitro and inserted into membrane vesicles do not undergo heterologous subunit-subunit associations. We have shown that alpha- and beta-subunits newly synthesized in vivo are not associated with each other. Our data indicate that the alpha-subunit is initially present in vivo in a conformation that is radically different from its native conformation in the mature receptor complex. We assume that beta-, gamma-, and delta-subunits also are synthesized as conformationally "immature" forms, but verification of this point must await the availability of new monoclonal antibody specificities. Our data indicate that only a fraction of the newly synthesized alpha-subunit undergoes conformational maturation to the 5S species which binds both alpha-bungarotoxin and anti-main immunogenic region monoclonal antibodies. alpha-Subunits synthesized during a 5-minute pulse labeling require 30 minutes for completion of this process. alpha-Subunits that do not undergo conformational maturation are degraded rapidly (t1/2 = 0.5 hr) ( Merlie et al. 1982). Assembly of alpha- and beta-subunits synthesized during a 5-minute pulse labeling lags for approximately 30 minutes and is not complete until 90 minutes. Finally, assembled receptors are transported to the surface and appear in the plasma membrane. These processes occur during expression of AChRs in differentiated myoblasts. We do not know how undifferentiated myogenic cells, in vivo or in tissue culture, differ with regard to any of these steps.(ABSTRACT TRUNCATED AT 400 WORDS)
Cold Spring Harb Symp Quant Biol 1983
PMID:The regulation of acetylcholine receptor expression in mammalian muscle. 658 56

A method has been developed for electron microscopic histochemical demonstration of phospholipase B, (lecithinase B, E C 3.1.1.5, lysolecithin acyl hydrolase), which hydrolyzes alpha- and beta-positions of phospholipids in mouse liver, kidney and adrenal tissues. Tissues either fixed in cold 1% paraformaldehyde or unfixed were cut into 40 micrometers frozen sections and were incubated at 37 degrees C in a medium at pH 6.6 or 4.5 containing 2 microM lysolecithin and 0.25 mM CaCl2 for 20 min. The fatty acids liberated by enzymatic hydrolysis were trapped as calcium precipitate and were converted to lead precipitate by treatment with lead nitrate. The reaction products were observed by electron microscopy to be localized on the end of the smooth endoplasmic reticulum at pH 6.6 and in lysosomes and lipid droplets at pH 4.5. It is concluded that the products showed the localization of phospholipase B activity.
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PMID:Electron microscopic demonstration of phospholipase B activity in the liver and the kidney of the mouse. 671 5

A rapid and simple method for the isolation of membranes from subcellular organelles is described. The procedure consists of diluting the organelles in ice-cold 100 mM Na2CO3 followed by centrifugation to pellet the membranes. Closed vesicles are converted to open membrane sheets, and content proteins and peripheral membrane proteins are released in soluble form. Here we document the method by applying it to various subfractions of a rat liver microsomal fraction, prepared by continuous density gradient centrifugation according to Beaufay et al. (1974, J. Cell Biol. 61:213-231). The results confirm and extend those of previous investigators on the distribution of enzymes and proteins among the membranes of the smooth and rough endoplasmic reticulum. In the accompanying paper (1982, J. Cell Biol. 93:103-110) the procedure is applied to peroxisomes and mitochondria.
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PMID:Isolation of intracellular membranes by means of sodium carbonate treatment: application to endoplasmic reticulum. 706 62

Intracellular transport and secretion of fibroin in the posterior silk gland cells of the silkworm, Bombyx mori, were investigated in relation to the radial microtubule and circular microtubule-microfilament systems of the cells. The silk glands were pulse-labelled for 3 min with [3H]glycine in vitro and then chased in media containing excess cold glycine and in some cases antimitotic reagents (colchicine or vinblastine) or cytochalasin (B or D), and the flow of the label in the glands was investigated by radioautography. It was revealed that the label initially located over the rough endoplasmic reticulum subsequently moves to the Golgi bodies to be condensed there. The secretory granules of fibroin or fibroin globules thus formed are transported via the radial microtubule system to the apical cytoplasm to be secreted there under some regulation by the circular microtubule-microfilament system. In the presence of colchicine or vinblastine, the secretion of fibroin was suppressed an marked accumulation of fibroin globules in the Golgi regions was observed, while in the presence of cytochalasin B or D the secretion was accelerated and extensive invagination of the luminal surface, which was probably due to the serial exocytosis of fibroin globules, was observed. These results suggest that the radial microtubule system and the circular microtubule-microfilament system are responsible for intracellular transport of fibroin globules from Golgi bodies to the apical cytoplasm and secretion by exocytosis at the luminal surface, respectively.
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PMID:Intracellular transport and secretion of fibroin in the posterior silk gland of the silkworm Bombyx mori. 719 44

Exposure of insect fat body to treatments which disrupt microtubules (colchicine, vinblastine sulfate and cold treatment) blocks intracellular transport between the Golgi complex and the plasma membrane but does not affect Golgi complex bead rings or transport from rough endoplasmic reticulum to the Golgi complex. Drugs which disrupt microfilaments (cytochalasins B and D) do not affect the bead rings or intracellular transport of secretory proteins at any level. Thus, intracellular transport between the rough endoplasmic reticulum and the Golgi complex and the arrangement of the beads in rings are both independent of the cytoskeleton. The ring arrangement is presumably maintained by interconnection(s) with rough endoplasmic reticulum membrane.
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PMID:The arrangement of the Golgi complex beads is not controlled by the cytoskeleton. 720 64

The seasonal variations in the ultrastructure and physiology of the epididymis of hedgehog were studied in relation to the reproductive functions. Five adult male hedgehogs were sacrificed every alternate month for one calendar year and the epididymis was fixed in Bouin's, Zenker and formol-calcium for light microscopy and in cold buffered glutaraldehyde, post-fixed in osmium tetraoxide for electron microscopy. The epididymal epithelium consists of four types of cells, the principal, the apical, the dark and the basal cells. The principal cells like other steroid synthesizing cells, contain the extensive Golgi apparatus, the smooth and the rough endoplasmic reticulum (SER and RER), the secretory vesicles and the lipid granules during the breeding season, but they are practically devoid of these cell organelles during regression, except for the retarded Golgi and moderate RER. The basal cell, on the other hand, show lipids and well developed organelles during regression but poorly developed structure in the sexually active hedgehog and possibly function as the cells storing lipids during regression and which are subsequently used at the beginning of the recrudescence. The epididymal epithelium recrudesces along with the seminiferous epithelium prior to the spermatozoa reaching the epididymal lumen, whereas the accessory sex glands which are also the extratesticular androgen dependent organs, still show regressed structure. Thus, the ultrastructural and the physiological observations suggest that the principal cells are probably the site of androgen synthesis and they become fully developed along with the cells in the testis on stimulation from the pituitary at the beginning of the recrudescence.
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PMID:Correlative study of the ultrastructure and the physiology of the seasonal regression of the epididymal epithelium in the hedgehog Paraechinus micropus. 725 98

The ultrastructure of the vesicle-containing axon profiles in the myenteric ganglia of the guinea-pig stomach was studied in specimens fixed by vascular perfusion and in specimens fixed by immersion in cold fixative after incubation in 5-hydroxydopamine. Three major types of vesicle-containing axon profile were identified in the ganglia: 1. Profiles containing numerous small, mainly shperical vesicles and only limited numbers of large dense-cored vesicles. In perfusion-fixed specimens, the small vesicles in these profiles were all clear. In specimens fixed by immersion after incubation in 5-hydroxydopamine, the profiles could be divided into three types: a) profiles containing small clear vesicles; b) profiles containing small dense-cored vesicles; c) profiles in which the small vesicles contained a peripheral rim of dense material. In these profiles, large vesicles which contained dense cores were rare. The mean diameter of the vesicles in the profiles was also significantly higher than in the profiles containing small clear vesicles. 2. Profiles containing flattened membrane-bounded structures. Reconstructions prepared from serial sections suggested that these structures represented sections through networks of smooth endoplasmic reticulum-like tubules rather than flattened vesicles. 3. Profiles containing many large dense-cored vesicles and few small clear vesicles. In perfusion-fixed specimens, the diameter of the dense-cored vesicles in these profiles was significantly higher than in the type 1 profiles. Type 1a and type 1c profiles were much more numerous than either type 2 or type 3 profiles. and type 1b profiles were few. Synaptic juctions were found in association only with type 1a profiles. Type 1a and type 1b profiles resembled cholinergic and adrenergic axon terminals. The remaining profiles may represent the terminals of different forms of peptidergic axon or of other as yet unidentified types of axon.
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PMID:Axonal terminal ultrastructure in the myenteric ganglia of the guinea-pig stomach. 739 72


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