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51.
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53.
Three classes of mutants resistant to the drug 6(p-hydroxyphenylazo)-uracil have been isolated from mutagenized cultures of CHO cells. One class of these mutants designated HPU R A exhibits a unique form of cross-resistance to bromodeoxyuridine in that it is resistant to this drug only in the presence of thymidine. The molecular basis of the BrdU resistance is unknown but does not appear to involve the known targets of the drug. An interesting feature of these mutants is that they give rise, at a high frequency, to a subpopulation of cells which are much more resistant to BrdU. 相似文献
54.
Two classes of CHO mutants resistant to the drug 6(p-hydroxyphenylazo)-uracil have been characterized. Both classes exhibited a nutritional requirement that could be satisfied by deoxypyrimidines and uridine but not other ribopyrimidines. A biochemical investigation of these mutants revealed a structural defect in ribonucleotide reductase resulting in a two- to fourfold increase in the Km for UDP and CDP. As a consequence of this lesion, the cells had imbalanced deoxypyrimidine pools and showed an increase in the rate of spontaneous mutation to 6-thioguanine resistance but not emetine resistance. 相似文献
55.
Carlo Capella Cesare Bordi Guido Monga Roberto Buffa Paolo Fontana Silvana Bonfanti Gianni Bussolati Enrico Solcia 《Virchows Archiv : an international journal of pathology》1978,377(2):111-128
Summary 10 cases of thyroid medullary carcinoma (TMC) have been studied ultrastructurally and histochemically. Well differentiated calcitonin-producing C cells were present in all tumours, being prevalent in 9 cases. 5-Hydroxytryptamine (5HT) storing cells were found in two cases, somatostatin immunoreactive cells in at least 5 cases and ACTH-immunoreactive cells in 4 cases. Ultrastructurally, at least 3 types of apparently non-C cells were observed. Type 1 cells with large, poorly osmiophilic granules resembling those of gastroenteropancreatic D cells, were present in 6 cases; they appeared to correlate well with somatostatin immunoreactive cells. Type 2 cells with large osmiophilic granules were found in 5 cases; they resembled ACTH-MSH cells of the human pituitary and may correspond to the ACTH-immunoreactive cells of light microscopy. Type 3 cells with small granules and an unknown function were found in 6 cases, always in scarce number. It is concluded that TMC, although mainly made up of C cells, usually contains large proportions of other endocrine cell types.Supported in part by grant N. 75.00630.04 from the Italian National Research Council (C.N.R.). P.F. is a fellow of the Fondazione Anna Villa Rusconi, Varese 相似文献
56.
Reiss J Bonin M Schwegler H Sass JO Garattini E Wagner S Lee HJ Engel W Riess O Schwarz G 《Molecular genetics and metabolism》2005,85(1):12-20
Molybdenum cofactor (Moco)-deficiency is a lethal autosomal recessive disease, for which until now no effective therapy is available. The biochemical hallmark of this disorder is the inactivity of the Moco-dependent sulfite oxidase, which results in elevated sulfite and diminished sulfate levels throughout the organism. In humans, Moco-deficiency results in neurological damage, which is apparent in untreatable seizures and various brain dysmorphisms. We have recently described a murine model for Moco-deficiency, which reflects all enzyme and metabolite changes observed in the patients, and an efficient therapy using a biosynthetic precursor of Moco has been established in this animal model. We now analyzed these mice in detail and excluded morphological brain damage, while expression analysis with microarrays indicates a massive cell death program. This neuronal damage appears to be triggered by elevated sulfite levels and is ameliorated in affected embryos by maternal clearance. 相似文献
57.
Hyperbaric oxygenation mitigates focal cerebral injury and reduces striatal dopamine release in a rat model of transient middle cerebral artery occlusion 总被引:16,自引:0,他引:16
Yang ZJ Camporesi C Yang X Wang J Bosco G Lok J Gorji R Schelper RL Camporesi EM 《European journal of applied physiology》2002,87(2):101-107
The usefulness of the administration of hyperbaric oxygen (HBO) in the treatment of acute focal cerebral ischemia remains
debatable. A significant association exists between focal cerebral injury and an excessive release of extracellular dopamine
(DA). In vivo microdialysis was used in the present study to examine the effect of HBO on DA release in the striatum during
ischemia and reperfusion in rats. The histological changes occurring were also evaluated. Focal cerebral ischemia was induced
by occlusion of the middle cerebral artery (MCA) using a surgically placed intraluminal filament. Control rats (n=8) were subjected to 1 h of ischemia, whilst the study rats (n=8) were in addition treated with HBO (2.8 atmospheres of absolute pressure 100% O2) during ischemia. Both groups were returned to breathing room air at normal pressure during reperfusion. Microdialysis samples
were continuously collected at 15 min intervals at 2 μl·min–1. The [mean (SE)] increase in release of striatal DA attained significance after 30 min of occlusion of MCA [170 (24)%], and
continued to increase [268 (26)% at 45 min] reaching a peak level at 60 min [672 (59)%] before returning to the baseline level
during the late reperfusion phase. There was no significant change in the level of DA in HBO treated rats during the period
of ischemia. A significant reduction in edema and neuronal shrinkage were observed by histological examination in HBO treated
rats when compared to the control rats. The results showed that HBO, when administered during ischemia, offered significant
neuroprotection in our experimental model of transient focal cerebral ischemia in the rat. The mechanism seems to imply, at
least in part, a reduced level of DA.
Electronic Publication 相似文献
58.
59.
Detection of Leishmania infantum kinetoplast DNA in laryngeal tissue from an immunocompetent patient
Guddo F Gallo E Cillari E La Rocca AM Moceo P Leslie K Colby T Rizzo AG 《Human pathology》2005,36(10):1140-1142
Mucosal leishmaniasis of the upper respiratory tract is usually associated with the visceral form or is found in immunosuppressed individuals. This report presents a case of isolated mucosal leishmaniasis in an immunocompetent patient, whose diagnosis mainly rested on histology and positive polymerase chain reaction result for Leishmania donovani in the laryngeal tissue. A 59-year-old man, who never lived outside Italy, showed a subglottic mucosal polypoid-like lesion. The typical morphological picture and positive polymerase chain reaction result for L donovani by DNA extracted from laryngeal biopsy specimens allowed the diagnosis of mucosal leishmaniasis. Specific amphotericin B therapy was started, resulting in clinical and endoscopic improvement. Increased knowledge about the histological and molecular tissue analysis of Leishmania enhances the diagnostic testing for mucosal leishmaniasis, as primary mucosal leishmaniasis may occur in both immunosuppresed and immunocompetent patients who travel to or reside in areas endemic for Leishmania. 相似文献
60.
MaxiK channel partners: physiological impact 总被引:7,自引:2,他引:7
Rong Lu Abderrahmane Alioua Yogesh Kumar Mansoureh Eghbali Enrico Stefani Ligia Toro 《The Journal of physiology》2006,570(1):65-72
The basic functional unit of the large-conductance, voltage- and Ca2 + -activated K+ (MaxiK, BK, BKCa ) channel is a tetramer of the pore-forming α-subunit (MaxiKα) encoded by a single gene, Slo , holding multiple alternative exons. Depending on the tissue, MaxiKα can associate with modulatory β-subunits (β1–β4) increasing its functional diversity. As MaxiK senses and regulates membrane voltage and intracellular Ca2 + , it links cell excitability with cell signalling and metabolism. Thus, MaxiK is a key regulator of vital body functions, like blood flow, uresis, immunity and neurotransmission. Epilepsy with paroxysmal dyskinesia syndrome has been recognized as a MaxiKα-related disorder caused by a gain-of-function C-terminus mutation. This channel region is also emerging as a key recognition module containing sequences for MaxiKα interaction with its surrounding signalling partners, and its targeting to cell-specific microdomains. The growing list of interacting proteins highlights the possibility that associations with the C-terminus of MaxiKα are dynamic and depending on each cellular environment. We speculate that the molecular multiplicity of the C-terminus (and intracellular loops) dictated by alternative exons may modulate or create additional interacting sites in a tissue-specific manner. A challenge is the dissection of MaxiK macromolecular signalling complexes in different tissues and their temporal association/dissociation according to the stimulus. 相似文献