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排序方式: 共有305条查询结果,搜索用时 15 毫秒
1.
M N Melo P Williams N M Rocha E H Babá W Mayrink M S Michalick C A da Costa M Dias P A Magalh?es 《Memórias do Instituto Oswaldo Cruz》1987,82(4):557-561
Attempts have been made to characterize two strains of Leishmania that became infective to golden hamsters only after they had been maintained for several years in a chemically defined culture medium. Observations were made on the growth rates of promastigotes in vitro, course of infection in hamsters, morphology of amastigotes, and electrophoretic mobility patterns of eight isoenzymes. Information was obtained about the buoyant densities of n-DNA and k-DNA, and one strain was tested against monoclonal antibodies. The identity of both strains remains obscure. 相似文献
2.
A. Shteyer D. Gazit I. Binderman I. A. Bab 《In vitro cellular & developmental biology. Plant》1987,23(1):15-20
Summary Cells of the dental papilla are capable of odontoblastic, fibroblastic, and endothelial differentiation and formation of dentin
and the dental pulp. In the present study dental papilla cells, obtained from human tooth buds (HDP cells), were cultured
in vitro through 3 to 7 passages. After exposure to prostaglandin E2 there was a marked decrease in intracellular cyclic AMP (cAMP) levels as compared to hormone-free controls. Parathyroid hormone
and calcitonin had stimulatory effects with 1 and 2 log increases in cAMP, respectively. The HDP cells showed moderate activity
of alkaline phosphatase, 1 log higher than that of hamster kidney fibroblasts (BHK 13) and 1 log lower than that of osteoblastic
osteosarcoma cells (ROS 17/2). When cultured for 4 or 8 wk in diffusion chambers (DC) implanted in athymic mice, many of the
HDP cells underwent odontoblastic morphodifferentiation with very long, single processes extending into the matrix. This matrix
contained banded and unbanded collagen fibers. Neither light nor electron microscopy of the DC content revealed mineral deposits.
These results suggest that HDP cells have an intrinsic potential for partial odontoblastic differentiation; inductive signals
like those originating from odontogenic epithelium are probably essential for the completion of hard tissue formation. 相似文献
3.
Summary Taurine which has antioxidant effects is also known to have effects on cell proliferation, inflammation and collagenogenesis. The aim of this study was to investigate the effect of taurine on incisional skin wounds.The mice incised on the dorsal area were divided into control and experimental groups. Saline was injected intraperitoneally to half of the animals in the control group and locally applied to the other half. Fifty mM taurine solution was given intraperitoneally to the first half of the experimental animals and locally to the second half of the experimental group.After four days of treatment, malondialdehyde (MDA) and histamine levels as well as the tensile strength of the wound tissue were measured. Structural alterations in epidermis and dermis were histologically evaluated.The locally administreated taurine significantly increased wound tensile strength by decreasing the MDA and histamine levels and prevented the degranulation of the mast cells. These observations suggest that taurine may be useful on wound healing. 相似文献
4.
Rositsa S. Milcheva Svetlozara L. Petkova Pavol Dubinsky Zuzana Hurniková Pavel Babál 《Biologia》2009,64(1):180-186
The in situ identification of carbohydrate structures in Trichinella spiralis intestinal larvae, adults and L1 muscular larvae was carried out by lectin histochemistry, with emphasis on the O-linked
glycans. The absence of reactivity with two lectins-TML and MAL indicated that Trichinella spiralis does not synthesize sialic acid. Reactivity with HPA, VVL-B4, PNA and UEA-I staining suggested that T. spiralis synthesizes and expresses on its cuticle O-linked glycans analogous to Tn-antigen (GalNAc-α-Ser/Thr), T-antigen (Gal-β1,3-GalNAc-α-Ser/Thr) and also structures analogous to A-blood group antigens (GalNAc-α1,3-Gal-β1,3(4)-(Fuc-α1,2-)-R). Expression of the saccharidic moieties is stage-specific. Blood group-A and T-antigen structures were identified
on the cuticle of the intestinal and muscular larvae. The Tn-antigen structure was missing in the intestinal larvae. Appropriate
ligands for WGA were not identified in the adult individuals. The obtained results may contribute to a better understanding
of the glycobiology of this parasitic nematode in relation to occupation of its intracellular niche. The presence of saccharidic
structures analogous to some of those expressed on the intestinal epithelial cells may serve as a protective shield on the
surface of the parasite. 相似文献
5.
A method for perfusion of isolated canine tibia is described. With this procedure the influence of different albumins on the uptake of tritiated 25-hydroxyvitamin D3 (3H-25(OH)D3) by the tibia has been studied. Bovine serum albumin at 1% concentration seems to be optimum for this system. This experimental approach seems to be useful for the study of mineral metabolism. 相似文献
6.
Irazú Contreras Marina T. Shio Annabelle Cesaro Philippe A. Tessier Martin Olivier 《PLoS neglected tropical diseases》2013,7(9)
The myeloid-related proteins (MRPs) 8/14 are small proteins mainly produced by neutrophils, which have been reported to induce NO production in macrophages. On the other hand, Leishmania survives and multiplies within phagocytes by inactivating several of their microbicidal functions. Whereas MRPs are rapidly released during the innate immune response, their role in the regulation of Leishmaniasis is still unknown. In vitro experiments revealed that Leishmania infection alters MRP-induced signaling, leading to inhibition of macrophage functions (NO, TNF-α). In contrast, MRP-primed cells showed normal signaling activation and NO production in response to Leishmania infection. Using a murine air-pouch model, we observed that infection with L. major induced leukocyte recruitment and MRP secretion comparable to LPS-treated mice. Depletion of MRPs significantly reduced these inflammatory events and augmented both parasite load and footpad swelling during the first 8 weeks post-infection, as also observed in MRP KO mice. On the contrary, mouse treatment with recombinant MRPs (rMRPs) had the opposite effect. Collectively, our results suggest that rapid secretion of MRPs by neutrophils at the site of infection may protect uninfected macrophages and favor a more efficient innate inflammatory response against Leishmania infection. In summary, our study reveals the critical role played by MRPs in the regulation of Leishmania infection and how this pathogen can subvert its action. 相似文献
7.
This study describes and recognises, using histological and microscopical examinations on a morphometrical basis, several gonad traits through the early life stages of Chiton articulatus and C. albolineatus. Gonadal ontogenesis, gonad development stages, sexual differentiation, onset of the first sexual maturity, and growth sequences or “early life stages” were determined. In addition, allometry between lengths and body weight pooled for both sexes per each chiton were calculated using equation Y = aXb. A total of 125 chitons (4≤TL≤40 mm, in total length “TL”) were used. All allometric relations showed a strong positive correlation (r), close to 1, with b-values above three, indicating an isometric growth. Gonadal ontogenesis and gonad development stages were categorised into three periods (“Pw” without gonad, “Pe” gonad emergence, and “Pf” gonadal sac formed) and four stages (“S0” gametocytogenesis, “S1” gametogenesis, “S2” mature, and “S3” spawning), respectively. Compound digital images were attained for each process. Periods and stages are overlapped among them and between species, with the following overall confidence intervals in TL: Pw 6.13–14.32 mm, Pe 10.32–16.93 mm, Pf 12.99–25.01 mm, S0 16.08–24.34 mm (females) and 19.51–26.60 mm (males), S1 27.15–35.63 mm (females) and 23.45–32.27 mm (males), S2 24.48–40.24 mm (females) and 25.45–32.87 mm (males). Sexual differentiation (in S0) of both chitons occurs first as a female then as a male; although, males reach the onset of the first sexual maturity earlier than females, thus for C. articulatus males at 17 mm and females at 32 mm, and for C. albolineatus males at 23.5 mm and females at 28 mm, all in TL. Four early life stages (i.e., subjuvenile, juvenile, subadult, and adult) are described and proposed to distinguish growth sequences. Our results may be useful to diverse disciplines, from developmental biology to fisheries management. 相似文献
8.
Lêda N. Regis Ridelane Veiga Acioli José Constantino Silveira Jr. Maria Alice Varjal Melo-Santos Wayner Vieira Souza Candida M. Nogueira. Ribeiro Juliana C. Serafim. da Silva Antonio Miguel Vieira Monteiro Cláudia M. F. Oliveira Rosangela M. R. Barbosa Cynthia Braga Marco Aurélio Benedetti Rodrigues Marilú Gomes N. M. Silva Paulo Justiniano Ribeiro Jr. Wagner Hugo Bonat Liliam César de Castro Medeiros Marilia Sa Carvalho André Freire Furtado 《PloS one》2013,8(7)
Aedes aegypti has developed evolution-driven adaptations for surviving in the domestic human habitat. Several trap models have been designed considering these strategies and tested for monitoring this efficient vector of Dengue. Here, we report a real-scale evaluation of a system for monitoring and controlling mosquito populations based on egg sampling coupled with geographic information systems technology. The SMCP-Aedes, a system based on open technology and open data standards, was set up from March/2008 to October/2011 as a pilot trial in two sites of Pernambuco -Brazil: Ipojuca (10,000 residents) and Santa Cruz (83,000), in a joint effort of health authorities and staff, and a network of scientists providing scientific support. A widespread infestation by Aedes was found in both sites in 2008–2009, with 96.8%–100% trap positivity. Egg densities were markedly higher in SCC than in Ipojuca. A 90% decrease in egg density was recorded in SCC after two years of sustained control pressure imposed by suppression of >7,500,000 eggs and >3,200 adults, plus larval control by adding fishes to cisterns. In Ipojuca, 1.1 million mosquito eggs were suppressed and a 77% reduction in egg density was achieved. This study aimed at assessing the applicability of a system using GIS and spatial statistic analysis tools for quantitative assessment of mosquito populations. It also provided useful information on the requirements for reducing well-established mosquito populations. Results from two cities led us to conclude that the success in markedly reducing an Aedes population required the appropriate choice of control measures for sustained mass elimination guided by a user-friendly mosquito surveillance system. The system was able to support interventional decisions and to assess the program’s success. Additionally, it created a stimulating environment for health staff and residents, which had a positive impact on their commitment to the dengue control program. 相似文献
9.
The effect of orally or intraperitoneally administered particulate 1,3-β-d-glucan (PBG), carboxymethylglucan (CMG) or sulfoethylglucan (SEG), obtained from the culture filtrate ofSaccharomyces cerevisiae, on the functions of murine peritoneal adherent cells (PC) (peroxidase activity, nitric oxide synthesis), on relative organ
mass and on proliferation of splenocytes was determined. The modulating activities after parenteral and non-parenteral administration
of these polysaccharides were compared. Significant enhancement of NO production was observed only afterin vitro cultivation of PC in the presence of lipopolysaccharide (LPS) in groups of mice treated repeatedly orally with CMG, PBG and
SEG at a dose of 50 mg/kg body mass. Peroxidase activity increased significantly after repeated oral administration of CMG
and PBG at doses 150 and 50 mg/kg, SEG 150 mg/kg body mass. The peroxidase activity and NO synthesis in mice given a single
intraperitoneal injection of glucans (15 mg/kg body mass) were slightly higher than those after oral administration. Neither
a significant enhancement of relative organ mass nor enhancement of the proliferative response of splenocytes toin vitro added stimuli (LPS, phytohemagglutinin) after repeated oral or single intraperitoneal administration of β-glucans was observed. 相似文献
10.
Svingor A Kardos J Hajdú I Németh A Závodszky P 《The Journal of biological chemistry》2001,276(30):28121-28125
3-isopropylmalate dehydrogenase (IPMDH) from the psychrotrophic bacterium Vibrio sp. I5 has been expressed in Escherichia coli and purified. This cold-adapted enzyme is highly homologous with IPMDHs from other organisms, including mesophilic E. coli and thermophilic Thermus thermophilus bacteria. Its molecular properties are similar to these counterparts. Whereas the E. coli and T. thermophilus enzymes are hardly active at room temperature, the Vibrio IPMDH has reasonable activity below room temperature. The thermal stabilities, conformational flexibilities (hydrogen-deuterium exchange), and kinetic parameters of these enzymes were compared. The temperature dependence of the catalytic parameters of the three enzymes show similar but shifted profiles. The Vibrio IPMDH is a much better enzyme at 25 degrees C than its counterparts. With decreasing temperature i.e. with decreasing conformational flexibility, the specific activity reduces, as well; however, in the case of the Vibrio enzyme, the residual activity is still high enough for normal physiological operation of the organism. The cold-adaptation strategy in this case is achieved by creation of an extremely efficient enzyme, which has reduced but still sufficient activity at low temperature. 相似文献