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排序方式: 共有211条查询结果,搜索用时 31 毫秒
1.
Nanocrystalline platinum with different morphologies is synthesized via electrochemical deposition technique. The nucleation mechanism and its structural effect over the electrodeposited Pt on carbon electrodes have been systematically studied. Powder X-ray diffraction, X-ray photoelectron spectroscopy, and field-emission scanning electron microscopy are employed to study nucleation, oxidation states, and Pt structure growth on a carbon electrode. This study reports significant development of Pt metal nanoparticles with different morphologies such as a sphere, flower, core-flower, and rod-like structure directly fabricated on carbon electrode while tuning the deposition parameters such as current density, time, temperature, pH during the deposition process. The proposed electrochemical route represents a superior fabrication procedure for large-scale electrode fabrication compared to a conventional method for preparing membrane electrode assemblies for fuel cell stacks.  相似文献   
2.
Urinary tract injuries during obstetric intervention   总被引:11,自引:0,他引:11  
A retrospective case record review of obstetric urinary tract injury in the Grampian region from 1976 to 1993 identified 16 cases of bladder injury (0.1 per 1000 deliveries, 1.4 per 1000 caesarean sections and four cases of ureteric injury (0.03 per 1000 deliveries, 0.27 per 1000 caesarean sections). Diagnosis of bladder injury was immediate, but of ureteric injury often delayed. Although the injury rates are lower than previously reported and previously reported risk factors not confirmed, this audit has resulted in guidelines for junior staff, compliance with which will be monitored, and every case of urinary tract injury will be reviewed.  相似文献   
3.
The complete nucleotide sequence of the large polymerase (L) protein of the avian metapneumovirus subgroup C strain Colorado was determined. The L protein gene of avian pneumovirus Colorado isolate (APV-C) was 6173 nucleotides in length from the gene-start to the gene-end and encoded a polypeptide of 2005 amino acids in length. The length of the L protein of APV-C was exactly the same as that of human metapneumovirus (hMPV) and one amino acid longer than the L protein of APV subgroup A. The L protein of APV-C showed 80% amino acid identity with the L protein of hMPV, but only 64% amino acid identity with the L protein of APV-A. The nucleotide and deduced amino acid sequences were compared with the corresponding sequences of eleven other paramyxoviruses. All six domains characteristic of paramyxovirus L proteins were also observed in the L protein of APV-C. All the polymerase core motifs in domain III were conserved to nearly 100% in the metapneumoviruses. Similarly, the putative ATP-binding motif in domain VI was completely conserved among the metapneumoviruses and differed in length, by one intermediate residue, from other paramyxoviruses. Phylogenetic analysis of the different L proteins also revealed a closer relationship between APV-C and hMPV.  相似文献   
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This study reports on the association of genetic variants selected from previous genome‐wide association studies for type 2 diabetic nephropathy in south Indians. Eight variants were genotyped in 601 type 2 diabetic subjects without nephropathy (DM) and 583 type 2 diabetic subjects with nephropathy (DN) by MassARRAY. The minor allele frequencies of rs11643718 SLC12A3 variant and rs741301 ELMO1 variant were significantly different between DM and DN groups (P = 0.029 and 0.016, respectively). A combined analysis showed that the subjects carrying the risk genotypes of both these variants (GG of rs11643718 + AG/AA of rs741301) had a significant association with DN with an odds ratio [adjusted for age, sex, Body Mass Index (BMI), HbA1c, and systolic Blood Pressure (BP)] of 1.73 (1.30–2.30, P = 1.72 × 10–4) as compared to subjects carrying all other genotype combinations. This is the first study to report a significant association of the SLC12A3 rs11643718 and ELMO1 rs741301 (Single nucleotide Polymorphism) SNPs with diabetic nephropathy in south Indians.  相似文献   
7.
After multiple discrete introductions of influenza A(H1N1)pdm09 virus into Sri Lanka, the virus was transmitted among humans, then swine. The spread of virus between geographically distant swine farms is consistent with virus dispersal associated with a vehicle used for swine transportation, although this remains unproven.  相似文献   
8.
The absence of preexisting neutralizing antibodies specific for the novel A (H7N9) influenza virus indicates a lack of prior human exposure. As influenza A virus–specific CD8+ T lymphocytes (CTLs) can be broadly cross-reactive, we tested whether immunogenic peptides derived from H7N9 might be recognized by memory CTLs established following infection with other influenza strains. Probing across multiple ethnicities, we identified 32 conserved epitopes derived from the nucleoprotein (NP) and matrix-1 (M1) proteins. These NP and M1 peptides are presented by HLAs prevalent in 16–57% of individuals. Remarkably, some HLA alleles (A*0201, A*0301, B*5701, B*1801, and B*0801) elicit robust CTL responses against any human influenza A virus, including H7N9, whereas ethnicities where HLA-A*0101, A*6801, B*1501, and A*2402 are prominent, show limited CTL response profiles. By this criterion, some groups, especially the Alaskan and Australian Indigenous peoples, would be particularly vulnerable to H7N9 infection. This dissection of CTL-mediated immunity to H7N9 thus suggests strategies for both vaccine delivery and development.Emerging unexpectedly in February 2013, the H7N9 influenza A virus (IAV) has thus far caused 137 human infections with 45 deaths (1). Clinical manifestations include major respiratory compromise, multiorgan failure, and exceedingly high serum cytokine and chemokine levels (2). Although May through September saw only five such cases, two more were recorded in October (1), indicating that H7N9 may return during the northern winter. Furthermore, the presence of a natural avian reservoir and the severity of the disease emphasized the need to focus on protective immunity. Most patients had contact with poultry within a week before clinical onset (2), suggesting that domestic birds are the source (2, 3). Even so, the potential for person-to-person spread is highlighted by ferret experiments (4) and instances of infection via close family contact (3). A very real concern is that further mutations may facilitate human-to-human transmission (5).Evidence from animal (6) and human studies (79) suggests that, in the absence of neutralizing antibodies (NAbs), preexisting memory CD8+ T lymphocytes (CTLs) directed at conserved and/or cross-reactive IAV peptide + class I HLA (pHLA1) epitopes can diminish disease severity. The recall of IAV-specific CTLs promotes recovery manifested by milder symptoms, diminished virus shedding and transmission (6, 7). A comprehensive analysis of the 2009 pandemic H1N1 IAV (H1N1pdm-2009) indicated that CTL memory provided some protection for the antibody naïve (9). Thus, cross-reactive CTL memory generated after a prior encounter with seasonal or pandemic IAVs, or by a CTL-directed vaccine, could potentially limit the severity of an H7N9 pandemic.The present analysis probes the extent of preexisting CTL immunity in populations that have not been exposed to the H7N9 virus. This potential for CTL recall is defined for HLA1s that are differentially prominent in various ethnicities. Using an evolutionary and immunological approach, we show substantial levels of immunogenic peptide conservation for nucleoprotein (NP) and matrix-1 (M1), with estimated coverage according to known HLA1 presentation profiles ranging between 16% and 57% of the global population. Overall, the findings support the view that it is important to consider developing vaccines with a T cell–based component that has the potential to protect against severe novel IAV infections. Furthermore, given that some ethnicities, including Australia’s Indigenous and Alaskan people, show evidence of a diminished HLA1-related response capacity, it is essential that health policy development and planning gives such groups priority in IAV vaccination campaigns. The 2009 H1N1 pandemic caused higher attack rates and morbidity among Indigenous populations in the Americas, New Zealand, and Australia (10).  相似文献   
9.
Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal tumors with immunohistochemical co‐expression of melanocytic and myoid markers. Vaginal PEComas have been described in only nine cases so far. We describe the case of a 65‐year‐old female with a large growth in the left lateral vaginal wall. Biopsy imprint smears showed dispersed tumor cells with anisonucleosis, multinucleation, and bizarre forms, suggestive of a malignant tumor. Histopathology, however, showed perivascular arrangement of clear epithelioid cells, focal necrosis, intracellular brown pigment in few cells, and mitotic activity at 2 to 3 per 50 high power fields. Immunohistochemical positivity for vimentin, HMB‐45, S‐100 protein, desmin, and MyoD1 assisted in rendering a final pathological diagnosis of malignant PEComa of the vagina. Further work‐up revealed metastatic deposits in liver and retroperitoneal lymph nodes. PEComa arising in vagina is an unusual phenomenon with the malignant variant being an extremely rare tumor. Awareness of the characteristic morphology and utilization of a panel of immunohistochemical stains are mandatory to be able to make a precise diagnosis and appropriate prognostication.  相似文献   
10.
PSAPP mice expressing the ‘Swedish’ amyloid precursor protein and the M146L presenilin 1 mutations are a well‐characterized model for spontaneous amyloid β plaque formation. Centella asiatica has a long history of use in India as a memory enhancing drug in Ayurvedic literature. The study investigated whether Centella asiatica extract (CaE) can alter the amyloid pathology in PSAPP mice by administering CaE (2.5 or 5.0 g/kg/day) starting at 2 months of age prior to the onset of detectable amyloid deposition and continued for either 2 months or 8 months. A significant decrease in amyloid β 1–40 and 1–42 was detectable by ELISA following an 8 month treatment with 2.5 mg/kg of CaE. A reduction in Congo Red stained fibrillar amyloid plaques was detected with the 5.0 mg/kg CaE dose and long‐term treatment regimen. It was also confirmed that CaE functions as an antioxidant in vitro, scavenging free radicals, reducing lipid peroxidation and protecting against DNA damage. The data indicate that CaE can impact the amyloid cascade altering amyloid β pathology in the brains of PSAPP mice and modulating components of the oxidative stress response that has been implicated in the neurodegenerative changes that occur with Alzheimer's disease. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
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