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91.
The effect of culture medium from fibroblast cultures of cystic fibrosis (CF) patients and healthy controls on the elemental composition of fibroblasts was investigated by X-ray microanalysis. Exposure of normal fibroblasts to culture medium from CF fibroblasts caused an increase in calcium level. Exposure of CF fibroblasts to culture medium from normal cells caused an increase of the sodium content of CF cells to approximately normal levels; the calcium level of the CF fibroblasts, however, remained abnormally high. The results may indicate that CF fibroblasts lack a factor needed for the regulation of sodium transport. CF fibroblast medium apparently contains a factor that interferes with the regulation of calcium transport. 相似文献
92.
Bo Hellman Janove Sehlin Inge-Bert Täljedal 《Pflügers Archiv : European journal of physiology》1978,378(2):93-97
Microdissected pancreatic islets of noninbredob/ob-mice were used to study ionic effects on the lanthanum-nondisplaceable45Ca2+ uptake by islet cells. Omission of Mg2+ from the incubation medium had no effect, but the45Ca2+ uptake was increased by omission of Na+ and decreased by omission of K+. Excess Mg2+ (1.2–15 mM) inhibited and excess K+ (4.7–25 mM) stimulated the45Ca2+ uptake in a concentration-dependent manner. Stimulation of45Ca2+ uptake in Na+-deficient islets was associated with an enhancement of the basal insulin release. Total abolishment of glucose-stimulated45Ca2+ uptake in K+-deficient islets did not preclude a significant secretory response to glucose. It is concluded that the lanthanum-nondisplaceable45Ca2+ uptake shows a partial correlation to insulin release. 相似文献
93.
The peptide melittin, the main constituent of bee venom is a potent stimulus for the generation of an eosinophil chemotactic factor (ECF) from human polymorphonuclear neutrophils, rat mast cells and rat peritoneal cells depleted in mast cells. Optimal EFC induction required a sublytic activation of the cells. With each cell type the kinetics of ECF generation were similar in that after an early rise in activity a steep fall off occurred at later times of incubation suggesting a mechanism of inactivation. The induction of ECF by melittin is increased in the presence of calcium. The polar portion of the melittin molecule (aminoacids 20–26) is responsible for the generation of the chemotactic activity. Other peptides of honey bee venom such as the mast cell degranulating peptide (MCD) or apamine do not initiate ECF release. It appears that melittin leads to ECF induction via the phospholipase A2-arachidonic acid dependent pathway of cell activation. Our data suggests that the lipid mediator ECF can be obtained from phagocytes and mast cells thus indicating the interdependence of inflammatory reactions. 相似文献
94.
Małgorzata Niezgódka Joanna Mikulska Maciej Ugorski Janusz Boratyński Józef Lisowski 《Molecular immunology》1981,18(3):163-172
Characterization of the human placental membrane receptor for human 125I-IgG is described. The receptor bound specifically both monomers and aggregates of human IgG. Human colostral IgA, bovine, sheep, pig, and horse IgG were not bound. No effect of pH in the range 6.6–7.4, ionic strength in the range 0.1–0.5, and temperature between 4 and 45°C on the binding was found. A water-soluble fraction containing the active receptor (glycoprotein fraction-PGP) was obtained from the placental membranes using lithium diiodosalicylate. The solubilized receptor interacted with IgG better at 4°C than at 20°C or 37°C. The results on replacement of monomeric IgG by aggregated IgG, and vice versa, suggest that both monomers and aggregates of human IgG, were bound to the same receptor sites. The apparent association constant for monomeric human IgG was 0.86 ± 0.2 × 107 mole?1, and 2.0 ± 0.16 × 1015 IgG molecules were bound per l mg of the membrane protein. Formaldehyde (0.1%), 2-mercaptoethanol (50 mM), and periodate (4 mM) showed no effect on the binding properties of the membrane-bound and on the solubilized receptor, as well. Higher concentrations of periodate (10 mM or 20 mM) decreased the binding of IgG to membranes but showed no effect on the water-soluble receptor. Both the membrane-bound and the solubilized receptor were sensitive to papain. Pronose abolished the receptor activity after prolonged proteolysis only. Neuraminidase did not affect the activity of the receptor. The decrease of the binding activity of the membrane-bound receptor by trypsin and phospholipase C was due to a release of a material containing an active receptor. No effect of trypsin or phospholipase C on the activity of solubilized receptor was observed. The results obtained suggest a protein character of the placental Fc receptor. After electrophoresis of 125I-labeled solubilized receptor in polyacrylamide gel in the presence of SDS, 2 major protein peaks with molecular weights of 74,000 and 104,000 and 3 minor peaks with molecular weights of 56,000, 144,000, and 163,000 were found. 相似文献
95.
Johan H. Baert Rikke J. Veys Kristien Ampe Jan A. De Boever 《International journal of experimental pathology》1996,77(2):73-78
It has recently been shown that triclosan protects the human skin from the inflammation that may be caused by exposure to sodium lauryl sulphate (SLS). The aim of the present study was to examine whether triclosan can protect the hamster cheek pouch mucosa from the irritation caused by exposure to SLS. After four daily applications of a paste containing SLS, the epithelium of the hamster cheek pouch showed consistently prominent structural changes, especially basal hyperplasia, acanthosis, hypergranulosis, and hyperkeratosis. Identical morphological changes were also observed after applications of a paste containing SLS together with triclosan. In contrast, after applications of a paste containing triclosan alone, the cheek pouch mucosa revealed a histological structure essentially similar to the non-treated control mucosa. From these results, we may conclude that SLS, but not triclosan, irritates the hamster cheek pouch epithelium. Moreover, triclosan does not protect the cheek pouch mucosa against structural changes induced by SLS. It must be taken into account that triclosan does not always offer protection against the side-effects of SLS. 相似文献
96.
Jean Valmier Michel Simonneau Sylvie Boisseau 《Pflügers Archiv : European journal of physiology》1989,414(3):360-368
The electrophysiological properties of a subset of dorsal root ganglion (DRG) neurons microdissected from 12-day-old (E12) mouse embryos and acutely isolated were analyzed as soon as 3 after their isolation. Two classes of neurons were defined according to their mean diameter. The larger diameter class was examined in this study. They display uniform cytoskeletal properties with co-expression of vimentin and neurofilament triplet proteins. Patch-clamp methods also revealed a homogeneous and limited repertoire of ionic channels that included (1) a TTX-sensitive Na+ current whose properties are similar to that reported in mature mammalian neurons, and (2) two types of K+ currents that can be compared with the delayed rectifier (I
k
) and the transient (I
a) potassium currents found in other mammalian preparations. It may be possible to use this in vitro model to examine the development of new types of currents, such as Ca2+ currents during neuronal growth and differentiation. 相似文献
97.
In vitro biosynthesis and core glycosylation of the histidine-rich protein of Plasmodium lophurae 总被引:2,自引:0,他引:2
We have characterized the early biosynthetic forms of the histidine-rich protein (HisRP), a major, granule-bound protein (Mr 58 000) of the avian malarial parasite Plasmodium lophurae. We have translated poly(A)-containing, size-selected parasite mRNA in the wheat germ cell-free system in the presence of [3H]histidine. HisRP was synthesized as a larger precursor (Mr 63 000). When dog pancreas microsomal membranes were present in the cell-free system during translation, a still larger form of HisRP (Mr 66 000) was detected. This larger form was segregated into the dog pancreas microsomal vesicles and was core glycosylated. Presumably, it corresponds to an intermediate form located in the parasite rough endoplasmic reticulum (RER). The difference in the Mr of approx. 8 000 between this RER associated 'pro' form and the granule-bound, mature form of HisRP suggests that proteolytic processing occurs upon transport from the RER to the granule. Segregation and core glycosylation were strictly coupled to translation and were not observed upon posttranslational addition of microsomal membranes. Thus, the early events in the biosynthesis of HisRP are similar to those established for secretory and lysosomal proteins. 相似文献
98.
A. A. Nekrasova E. A. Zharova R. I. Sokolova 《Bulletin of experimental biology and medicine》1977,83(4):456-458
Direct correlation was found in intact rats between the kallikrein activity of the urine, on the one hand, and the diuresis, sodium excretion, and ability of the kidneys to concentrate the urine on the other hand. Small doses of indomethacin (2 mg/kg for 5 days) increased the kallikrein activity of the urine four-fold and, at the same time, increased the diuresis; large doses (5 mg/kg for 5 days) lowered the kallikrein activity of the urine and halved the diuresis, reduced the sodium excretion by two-thirds, and depressed the ability of the kidneys to concentrate the urine. Indomethacin may perhaps modify the synthesis not only of prostaglandins, but also of kallikrein, and this is reflected in the state of the kidney function.All-Union Cardiological Scientific Center, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR E. I. Chazor.) Translated from Byulleten' Éxperimental'noi Biologii i Meditsiny, Vol. 83, No. 4, pp. 399–400, April, 1977. 相似文献
99.
Revenko SV Borovik AS Makhan'kov YV 《Bulletin of experimental biology and medicine》2003,135(6):521-525
Signals of individual muscle vasoconstrictor efferents of gastrocnemius muscle were recorded in narcotized cat during rise and fall of systemic arterial pressure induced by phenylephrine and sodium nitroprusside, respectively. In control, mean discharge rate of these efferents was 2.0±0.4 Hz. Phenylephrine (45 g/kg) increased arterial pressure from 120.3±4.2 to 170.7±8.2 mm Hg. This increase was accompanied by a short-term (5-10 sec) decrease in discharge rate of muscle vasoconstrictor efferents to 0.5±0.3 Hz followed by virtually complete recovery of muscle discharge rate against the background of increased arterial pressure. Sodium nitroprusside (30 g/kg) decreased arterial pressure from 132.8±6.2 to 64.1±4.3 mm Hg. Under these conditions the discharge rate of vasoconstrictor efferents increased to 3.5±0.6 Hz and remained at this level throughout the hypotension period (2-3 min). Unloading of baroreceptors (occlusion of the carotid artery) increased the discharge rate of muscle vasoconstrictor efferents throughout the occlusion period (up to 30 sec). Thus, blood pressure rise and drop induced asymmetric by their duration changes in the discharge responses of muscle vasoconstrictor efferents. Phenylephrine increased asymmetry of the vasoconstrictor component of the baroreflex and induced cumulative rise of discharge rate of muscle vasoconstrictor efferents in response to a series of short-term reversible blood pressure jumps caused by repeated occlusions of the abdominal aorta. Our findings extend our knowledge on the efferent component of the baroreflex regulation and on possible mechanisms of hypertension. 相似文献
100.
Starkus JG Varga Z Schönherr R Heinemann SH 《Pflügers Archiv : European journal of physiology》2003,447(1):44-54
Potassium channels are regulated by protons in various ways and, in most cases, acidification results in potassium current reduction. To elucidate the mechanisms of proton-channel interactions we investigated N-terminally truncated Shaker potassium channels (Kv1 channels) expressed in Xenopus oocytes, varying pH at the intracellular and the extracellular face of the membrane. Intracellular acidification resulted in rapid and reversible channel block. The block was half-maximal at pH 6.48, thus even physiological excursions of intracellular pH will have an impact on K+ current. The block displayed only very weak voltage dependence and C-type inactivation and activation were not affected. Extracellular acidification (up to pH 4) did not block the channel, indicating that protons are effectively excluded from the selectivity filter. Channel current, however, was reduced greatly due to marked acceleration of C-type inactivation at low pH. In contrast, inactivation was not affected in the T449V mutant channel, in which C-type inactivation is impaired. The pH effect on inactivation of the wild-type channel had an apparent pK of 4.7, suggesting that protonation of extracellular acidic residues in Kv channels makes them subject to pH regulation. 相似文献