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51.
Fuentes V Toledano M Osorio R Carvalho RM 《Journal of biomedical materials research. Part A》2003,66(4):850-853
Our purpose in this study was to determine the microhardness of superficial and deep dentin by means of two indentation methods (Knoop and Vickers) under two different applied loads. Twelve dentin discs approximately 2-mm thick were obtained from both superficial and deep dentin by transversally sectioning the crowns of sound, extracted human third molars with a diamond blade under water irrigation. Dentin surfaces were sequentially polished, and indentations (n = 20 per surface) were performed with either Vickers indentor at loads of 300 and 500 g, respectively, or Knoop indentor at loads of 50 and 100 g, respectively. Average Vickers hardness number (VHN) and Knoop hardness number (KHN) were calculated and treated with two-way analysis of variance (ANOVA) and Student's t test. Microhardness of dentin was not influenced by the different loads applied for both indentation methods. Knoop hardness was significantly higher for superficial than for deep dentin (p < 0.05). Conversely, Vickers hardness was not significantly different for both substrates (p > 0.05). Differences in dentin hardness as a function of depth exist, but they might not be relevant, and no alteration of the distribution of stresses along the adhesive interface is expected. 相似文献
52.
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54.
Acute liver failure was induced in rats by CCl4 administration and its effects on the hepatic Krebs cycle and gluconeogenic fluxes were evaluated in situ by 13C NMR isotopomer analysis of hepatic glucose following infusion of [U-13C]propionate. In fed animals, CCl4 injury caused a significant increase in relative gluconeogenic flux from 0.80+/-0.10 to 1.34 +/-0.24 times the flux through citrate synthase (p<0.01). In 24-h fasted animals, CCl4-injury also significantly increased relative gluconeogenic flux from 1.36+/-0.16 to 1.80+/-0.22 times the flux through citrate synthase (p<0.01). Recycling of PEP via pyruvate and oxaloacetate was extensive under all conditions and was not significantly altered by CCl4 injury. CCl4 injury significantly reduced hepatic glucose output by 26% (42.8+/-7.3 vs 58.1+/-2.4 micromol/kg/min, p=0.005), which was attributed to a 26% decrease in absolute gluconeogenic flux from PEP (85.6+/-14.6 vs 116+/-4.8 micromol/kg/min, p<0.01). These changes were accompanied by a 47% reduction in absolute citrate synthase flux (90.6+/-8.0 to 47.6+/-8.0 micromol/kg/min, p<0.005), indicating that oxidative Krebs cycle flux was more susceptible to CCl4 injury. The reduction in absolute fluxes indicate a significant loss of hepatic metabolic capacity, while the significant increases in relative gluconeogenic fluxes suggest a reorganization of metabolic activity towards preserving hepatic glucose output. 相似文献
55.
Carvalho TM Ferreira AG Coimbra ES Rosestolato CT De Souza W 《Journal of submicroscopic cytology and pathology》1999,31(3):325-333
The distribution of microtubules, microfilaments, mitochondria, Golgi complex and endosomes/lysosomes was analyzed in Vero cells allowed to interact for different periods of time with the pathogenic protozoan Trypanosoma cruzi and observed by confocal laser scanning microscopy. Microtubules were revealed using a mouse monoclonal anti-alpha-tubulin antibody. Actin filaments were revealed using phalloidin-rhodamine. To identify mitochondria, endosomes/lysosomes and the Golgi complex the cells were labelled with Rhodamine 123, Lucifer yellow and C6-NBD-ceramide, respectively. During cell invasion actin filaments concentrate at the site of parasite penetration in some, but not in all cells, probably depending upon the mechanism used by the trypomastigote form to penetrate into the host cells. Following internalization the trypomastigote form gradually changes into the amastigote form, disruption of the parasitophorous vacuole membrane takes place and the amastigote form enters in direct contact with host cell structures and organelles, and starts to divide. The presence of the parasite in the cytoplasm of the host cell did not induce significant changes in the distribution of actin filaments, microtubules, the Golgi complex, mitochondria and endosomes/lysosomes during the first 48 h of infection. Amastigote forms were seen close to the microtubules. After 72 h of interaction, the number of microtubules and microfilaments around the parasites was reduced and lysosomes and mitochondria were seen in between the parasites. 相似文献
56.
Permeation of human ovarian tissue with cryoprotective agents in preparation for cryopreservation 总被引:18,自引:10,他引:18
Newton H; Fisher J; Arnold JR; Pegg DE; Faddy MJ; Gosden RG 《Human reproduction (Oxford, England)》1998,13(2):376-380
The recent improvements in the treatment of cancer by chemo- and
radiotherapy have led to a significant increase in the survival rates of
patients with malignant disease, but at the expense of distressing side
effects. One major problem, especially for younger patients, is that
aggressive therapy destroys a significant proportion of the follicular
population, which can result in either temporary or permanent infertility.
Freeze-banking pieces of ovarian cortex prior to treatment is one strategy
for preserving fecundity. When the patient is in remission, fertility
could, theoretically, be restored by autografting the thawed tissue at the
orthotopic site or by growing isolated follicles to maturity in vitro.
Recent studies have found good follicular survival in frozen-thawed human
ovarian tissue but to optimize the process an effective cryopreservation
method needs to be developed. An essential part of such a technique is to
permeate the tissue with a cryoprotectant to minimize ice formation and the
extent of this equilibration is an important determinant of post-thaw
cellular survival. In the current study, we have investigated the diffusion
of four cryoprotective agents into human tissue at both 4 degrees C and 37
degrees C. We have also studied the effect of adding different
concentrations of the non penetrating cryoprotective agent, sucrose, to the
freezing media using the release of lactate dehydrogenase as a measure of
its protective effect. At 4 degrees C propylene glycol and glycerol
penetrated the tissue significantly slower than either ethylene glycol or
dimethyl sulphoxide. At the higher temperature of 37 degrees C all four
cryoprotectants penetrated at a faster rate, however concern about enhanced
toxicity prevents the use of these conditions in practice. Thus, the
results suggest that the best method of preparing tissue for freezing is
exposure for 30 min to 1.5 M solutions of ethylene glycol or dimethyl
sulphoxide at 4 degrees C; this achieved a mean tissue concentration that
was almost 80% that of the bathing solution. We also report that the
addition of low concentrations of sucrose to the freezing medium does not
have a significant protective effect against freezing injury.
相似文献
57.
Stein TP; Oram-Smith JC; Leskiw MJ; Wallace HW; Long LC; Leonard JM 《The American journal of physiology》1976,230(5):1321-1325
58.
Evidence of genetic heterogeneity in the autosomal recessive adult forms of limb-girdle muscular dystrophy following linkage analysis with 15q probes in Brazilian families. 下载免费PDF全文
M R Passos-Bueno I Richard M Vainzof F Fougerousse J Weissenbach O Broux D Cohen J Akiyama S K Marie A A Carvalho et al. 《Journal of medical genetics》1993,30(5):385-387
The autosomal recessive limb-girdle muscular dystrophies (LGMD) represent a heterogeneous group of diseases which may be characterised by one or more autosomal loci. A gene at 15q has recently been found to be responsible for a mild form of LGMD in a group of families from the isolated island of Réunion, now classified as LGMD2. Based on results of eight out of 11 large Brazilian LGMD families of different racial background (which were informative for the closest available probe to the LGMD2 gene), we confirmed linkage to the LGMD2 gene at 15q in two of these families and exclusion in six others. These data provide the first evidence of genetic heterogeneity for the autosomal recessive limb-girdle muscular dystrophies. 相似文献
59.
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
60.
Inverse association between skin response to aeroallergens and Schistosoma mansoni infection 总被引:9,自引:0,他引:9
Araujo MI Lopes AA Medeiros M Cruz AA Sousa-Atta L Solé D Carvalho EM 《International archives of allergy and immunology》2000,123(2):145-148
BACKGROUND: Helminthic infections and allergic disease are highly prevalent in many areas of the world. It is known that IgE antibodies are involved in the pathogenesis of both helminthiasis and atopy. However, the consequences of the presence of helminthic infections in atopic patients are still not completely understood. METHODS: Subjects infected by Schistosoma mansoni with more than 200 eggs/g of feces (n = 42) and uninfected subjects (n = 133) were selected from an endemic area of schistosomiasis. The history of allergy and results of the immediate hypersensitivity prick tests with inhalant allergen extracts were registered. Total IgE and IgE specific to S. mansoni and aeroallergens were measured in serum by ELISA. RESULTS: The proportion of individuals with a positive skin test to allergens was higher in the uninfected group (24.3%) than in the group with more than 200 eggs/g of feces (4.8%). The odds of atopy (defined as a positive test for at least one of the antigens) were 5 times higher (odds ratio = 7.0; 95% confidence interval = 1.6-31.1%; p = 0.01) in the uninfected group, after taking into account the potential influence of gender and age. While there was a tendency for higher total and S. mansoni-specific IgE levels in infected patients, an opposite trend, that is higher aeroallergen-specific IgE, was observed in uninfected subjects. CONCLUSIONS: There was a strong and statistically significant inverse association between the immediate skin test response to common aeroallergens and infection by S. mansoni. The results indicate that immediate hypersensitivity reactions may be suppressed in S. mansoni-infected individuals. 相似文献