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81.
NMR studies on energy metabolism of immobilized primary neurons and astrocytes during hypoxia, ischemia and hypoglycemia 总被引:1,自引:0,他引:1
Alves PM Fonseca LL Peixoto CC Almeida AC Carrondo MJ Santos H 《NMR in biomedicine》2000,13(8):438-448
Changes in high-energy phosphate metabolites (ATP and phosphocreatine) were monitored, in real time, by 31P-nuclear magnetic resonance in primary cell cultures of neurons and astrocytes during periods of hypoxia, ischemia and hypoglycemia, and also during the recovery periods following the re-establishment of standard conditions. Cells were immobilized in basement membrane gel threads and perfused with oxygen-depleted medium (oxygen concentration below 30 microM), to create hypoxic conditions, or with aerobic medium (oxygen concentration approximately 460 microM) containing different concentrations of glucose (hypoglycemia). Ischemic conditions were imposed by stopping perfusion for different periods of time (15 min to 2 h). The experimental set-up enabled the acquisition of 31P-spectra with high signal-to-noise ratio within 10-20 min for both cell types. The effect of hypoxia on glucose metabolism was assessed by 13C-NMR using [1-13C]glucose as substrate. The levels of ATP and PCr in astrocytes were unaffected during hypoxia (up to 2 h), but decreased notably under ischemia. In neurons, hypoxic periods caused a sharp drop of the ATP and PCr levels, and considerable damage to the capacity of neurons to replenish the ATP and PCr pools upon returning to normoxic conditions. However, neurons were remarkably less sensitive to ischemic conditions, the ATP and PCr pools being restored quickly, even after 2 h under challenging conditions. The data show that neurons were more resistant to ischemia than astrocytes, and suggest that the capacity to sustain the pools of ATP and PCr was part of the neuronal protective strategy. 相似文献
82.
Parra ER Canzian M Saber AM Coêlho RS Rodrigues FG Kairalla RA de Carvalho CR Capelozzi VL 《Pathology, research and practice》2004,200(10):701-705
Previous reports indicate that enlarged hilar and mediastinal lymph nodes caused by sarcoid-like reactions may develop after curative resection of cancer, and their presence does not necessarily denote neoplastic recurrence. Reports further suggest that coexisting pulmonary infiltrates in this setting may be related to sarcoidosis. In this study, we describe two patients who had resected lung and gastric cancer and who later developed pulmonary interstitial infiltrate, concurrent with progressive mediastinal lymphadenopathy initially thought to be caused by intrathoracic dissemination of their cancer. These changes were shown by open lung biopsy to be a benign, granulomatous reaction interpreted as sarcoidosis. Thus, it is important to recognize this clinical pattern when pulmonary infiltrates develop after complete treatment of cancer in an otherwise relapse-free patient and to encourage lung or lymph node biopsy in these particular settings in order to confirm a sarcoid-like reaction, thereby avoiding unnecessary chemotherapy for presumed tumor recurrence. 相似文献
83.
N. Casamitjana J. Gil E. Campos M. Santos N. Nogués A. Ribera E. Palou 《Tissue antigens》2001,58(4):269-271
We report here the identification of a novel DQB1*06 allele, DQB1*0618, found in a bone marrow donor. The new allele was detected during routine DNA-based HLA typing by an ambiguous pattern of probe hybridization, obtained by polymerase chain reaction using sequence-specific oligonucleotides (PCR-SSO). Molecular cloning and sequencing confirmed that the new allele is identical to DQB1*0609 at exon 2 except for 3 nucleotide substitutions at positions 353, 356 and 367, also found in other alleles. These nucleotide changes may explain its anomalous reactivity. 相似文献
84.
Several techniques have been developed for protein immunolocalization in meiotic cells. However, most of them include treatments that lead to cell disruption and are only suitable for prophase-I cells. We describe a novel squash procedure of cell preparation for protein immunolabelling of different meiotic stages. This procedure is an alternative to both cryosectioning and whole spreading procedures. We present results obtained in mouse spermatocytes with three different antibodies: the MPM-2 mAb against mitotic phosphoepitopes, an anticentromere serum and a polyclonal serum against the SCP3 protein of the axial elements and lateral elements of the synaptonemal complex. The procedure was tested for single and double immunolabelling. With this technique a large number of cells at different meiotic stages can be analysed. Cell stages are easily identified and cell and chromosome structures are preserved. Thus, it allows the study of chromosome behaviour and the relations hips between the different structural elements of the cell throughout meiotic divisions. Our procedure is also suitable for three-dimensional (3D) analyses and proved to be reliable in a wide range of systems including insects and mammals. In addition, the procedure may be interesting to obtain a rapid immunological diagnosis. 相似文献
85.
86.
Mammalian transforming growth factor beta1 activated after ingestion by Anopheles stephensi modulates mosquito immunity 下载免费PDF全文
Luckhart S Crampton AL Zamora R Lieber MJ Dos Santos PC Peterson TM Emmith N Lim J Wink DA Vodovotz Y 《Infection and immunity》2003,71(6):3000-3009
During the process of bloodfeeding by Anopheles stephensi, mammalian latent transforming growth factor beta1 (TGF-beta1) is ingested and activated rapidly in the mosquito midgut. Activation may involve heme and nitric oxide (NO), agents released in the midgut during blood digestion and catalysis of L-arginine oxidation by A. stephensi NO synthase (AsNOS). Active TGF-beta1 persists in the mosquito midgut to extended times postingestion and is recognized by mosquito cells as a cytokine. In a manner analogous to the regulation of vertebrate inducible NO synthase and malaria parasite (Plasmodium) infection in mammals by TGF-beta1, TGF-beta1 regulates AsNOS expression and Plasmodium development in A. stephensi. Together, these observations indicate that, through conserved immunological cross talk, mammalian and mosquito immune systems interface with each other to influence the cycle of Plasmodium development. 相似文献
87.
dos Santos CN Rocha CF Cordeiro M Fragoso SP Rey F Deubel V Desprès P 《Virus research》2002,90(1-2):197-205
We have investigated the genetic diversity of dengue type-1 (DEN-1) virus in Brazil. The full nucleotide sequences of three DEN-1 virus isolated from DEN fever (DF) and DEN hemorrhagic fever patients in northeastern Brazil in 1997 (BR/97) and one from a DF patient in the south of Brazil in 2001 (BR/01) were compared to that of the reference strain BR/90 obtained in the city of Rio de Janeiro in 1990. Sequence analysis showed that the structural proteins were remarkably conserved between all isolates. A total of 27 amino acid changes occurred throughout the non-structural proteins. Among them, nine amino acid substitutions were specific of BR/97 and BR/01 isolates, indicating that in situ evolution of these strains had occurred. Within the BR/97 and BR/01 samples, some amino acid substitutions have been previously identified in DEN-1 virus strains sequenced so far, suggesting that recombination events might have occurred. 相似文献
88.
H. de Lencastre I. Couto I. Santos J. Melo-Cristino A. Torres-Pereira A. Tomasz 《European journal of clinical microbiology & infectious diseases》1994,13(1):64-73
Fifteen pediatric patients as well as the five nursing staff of the Burn Unit of the Hospital D. Estefania in Lisbon, Portugal, were assayed at weekly intervals over a five-month period in order to identify the nature and number of methicillin-resistantStaphylococcus aureus (MRSA) clones associated with colonization and wound infection. Methicillin resistance was confirmed by amec-specific DNA probe. MRSA isolates were classified into chromosomal types (clones) on the basis of a variety of techniques: (i) ribotyping; (ii) restriction digestion by the endonucleaseClaI followed by Southern hybridization with themecA-specific DNA probe and (iii) by hybridization with Tn554; and (iv) pulsed-field electrophoresis (PFE) ofSmaI digests followed by (v) Southern hybridization with themecA DNA probe. A sixth, physiological technique (population analysis) was used to define the mode of phenotypic expression of methicillin resistance in each isolate. All isolates carried a single, common polymorph (ClaI type III) of themecA gene. Hybridization with Tn554 resolved these isolates to two novel patterns (alpha and beta), of which one (Tn554 alpha) was predominant (90 %). This pattern could be further resolved to four closely related PFE types (A through D). In contrast, all isolates with the Tn554 beta pattern belonged to an additional, grossly different PFE type E. The Tn554 beta class was also unique in that these bacteria carried themecA gene in aSmaI fragment smaller (about 170 kb) than that found in the alpha type strains (194 kb). Most isolates (83 %) showed a single heterogeneous (population analysis Class 3) mode of resistance expression. The data demonstrate the full capacity of the globally rare (ClaI type III) MRSA clone for colonization and virulence. The results also document the stability of the complex heterogeneous resistance phenotype as well as the stability of the chromosomal types under conditions of in vivo carriage over a period of several months. In a few isolates the samemecA polymorph was present in several, grossly different genetic backgrounds, suggesting horizontal transfer of themecA gene. 相似文献
89.
Suppression of thyrotropin in the low-thyroxine state of severe nonthyroidal illness 总被引:6,自引:0,他引:6
R E Wehmann R I Gregerman W H Burns R Saral G W Santos 《The New England journal of medicine》1985,312(9):546-552
In a prospective study, we assessed the role of thyrotropin in the development of the low-thyroxine state that is associated with severe illness. We measured the serum thyrotropin and thyroid hormone concentrations longitudinally in 35 patients with hematopoietic cancer or aplastic anemia who were treated by bone-marrow transplantation. In 19 patients thyroxine declined sharply after bone-marrow transplantation and was associated with a reduction of the serum thyrotropin in the 17 patients tested, often to levels below the normal range. The serum triiodothyronine level, free thyroxine index, and free thyroxine level also declined in these patients. In the patients who recovered, clinical improvement was accompanied by the return of thyrotropin and thyroid hormone concentrations to their pretreatment ranges. These and related findings suggest that the low-thyroxine state of severe illness is the result of several events, one of which is failure of the normal negative-feedback control of the pituitary-thyroid axis due to illness-associated, decreased secretion of thyrotropin. The notion that such patients are "euthyroid" must be questioned, but the possible value of thyroid hormone-replacement therapy in these circumstances remains to be determined. 相似文献
90.
Nascimento Jdos S Giambiagi-deMarval M de Oliveira SS Ceotto H dos Santos KR Bastos Mdo C 《Research in microbiology》2005,156(8):837-842
Among 363 strains of Staphylococcus aureus, 21 were shown to produce bacteriocins (Bac), antimicrobial peptides with potential biotechnological applications. This collection includes strains which are either isolated from food, patients and healthy cattle, or are involved in subclinical bovine mastitis. From these 21 strains, 17 were shown to carry closely-related 8.0-kb Bac plasmids encoding bacteriocins either identical to or similar to aureocin A70, a bacteriocin able to inhibit strains of Listeria monocytogenes, a food-borne pathogen. Such findings prompted us to investigate the genetic relationships among these Bac+ strains. To obtain more discriminatory results, a combined analysis of AP-PCR, rep-PCR, and a modified PCR technique that we designated SD-PCR was employed. The 17 Bac+ strains harboring 8.0-kb Bac plasmids exhibited seven fingerprint patterns. One such genotype was composed of 8 out of the 11 strains associated with bovine mastitis, which suggests the prevalence of a clone of Bac+ strains involved in this animal infection carrying 8.0-kb Bac plasmids. Our data support the assumption that Bac+ strains of S. aureus carrying genetically related 8.0-kb Bac plasmids do not belong to a single clone. It seems, therefore, that 8.0-kb Bac plasmids have spread horizontally among different S. aureus strains. There also seems to be genetic diversity among the remaining Bac+ strains analyzed. 相似文献