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排序方式: 共有482条查询结果,搜索用时 15 毫秒
1.
2.
Limited-field-of-view radio-frequency receiver antennas provide improved near-field sensitivity for magnetic resonance imaging by decreasing the antenna volume. The Helmholtz-type surface coil, consisting of two flat rings, is an organ-encompassing antenna that takes advantage of this principle to yield an improved signal-to-noise ratio (S/N). The coil was tested in a group of 50 patients and 16 healthy volunteers. Images obtained with the Helmholtz coil demonstrated quantitatively superior S/N of 2.2-fold or greater than that of comparison body coil images, as well as qualitatively superior anatomic resolution. 相似文献
3.
Genotype-phenotype correlation for nucleotide substitutions in the IgII- IgIII linker of FGFR2 总被引:6,自引:3,他引:3
4.
Uroscopy in the 21st century: high-field NMR spectroscopy 总被引:1,自引:1,他引:0
Neild GH; Foxall PJ; Lindon JC; Holmes EC; Nicholson JK 《Nephrology, dialysis, transplantation》1997,12(3):404-417
From the experiments described, it can be seen that there are different
research approaches that can be taken and these are summarized in Table 1.
Whereas much scientific research is principally hypothesis led, there
remains, nevertheless, an important place for exploratory research. High
resolution NMR can measure, directly and simultaneously, a wide range of
endogenous metabolites in biological fluids and has the unique capability
of providing structural information on the metabolites detected. It has
proved to be a powerful research tool with which to study inherited
metabolic diseases, renal disease, drug metabolism, and toxicity, and can
be used to monitor the effects of drug therapy. For instance, by using a
library of experimental toxins one can map the metabolic profile of
site-specific nephron injury. With this approach in man one could
eventually take an unknown disease such as Balkan nephropathy and predict
the initial site of tubular injury, the mode of injury and therefore the
kind of toxin capable of producing that injury. NMR spectroscopic
techniques are still advancing rapidly, with ever increasing sensitivity
and sophistication of NMR pulse sequences to enhance structural elucidation
in complex mixtures. Given the advances in directly coupled HPLC-NMR and
even HPLC-NMR-mass spectroscopy it is likely that these technologies in
conjunction with pattern recognition will make major contribution to our
understanding of renal processes and provide new diagnostic insights in the
21st century.
相似文献
5.
Introduction : Hypertrophic scar is a devastating sequel to burns and other tangential skin injuries. It follows deep dermal injuries and does not occur after superficial injuries. Nitric oxide (NO) plays many important roles in wound healing from inflammation to scar remodeling. Studies have shown that expression of nitric oxide synthase and nitric oxide production are decreased in human hypertrophic scar. However little is known about NO involvement in the early stages of hypertrophic scarring, because of the lack of an animal model. It was recently reported that the female red Duroc pig (FRDP) makes thick scar, which is similar to human hypertrophic scar. We hypothesized that NO production in wounds on the female, red Duroc pig is similar to that of human hypertrophic scar and that NO involvement in deep wounds is different from that in superficial wounds. Methods : Superficial (0.015” to 0.030”) and deep (0.045” to 0.060”) wounds were created on the backs of four FRDPs. Biopsies were collected at weeks 1.5, 4, 8 and 21 post wounding including samples of uninjured skin. Nitric oxide levels were measured with the Griess reaction assay and normalized with tissue protein level. Results : Superficial wounds healed with an invisible scar whereas the deep wounds healed with scar resembling mild hypertrophic scar. The thickness of the scars from the deep wounds was significantly greater than uninjured skin and healed superficial wounds (p < 0.01). NO levels were increased at 1.5 weeks in deep wounds compared to superficial wounds and uninjured skin (p < 0.05). At 8 weeks, NO levels in deep wounds had returned to the level of uninjured tissue and superficial wounds. By 21 weeks, NO levels had decreased significantly when compared to superficial wounds (p < 0.01). There were no differences in NO levels between uninjured skin and superficial wounds at any time point (p > 0.05). Conclusions : NO production is similar in late, deep wounds on the female, red Duroc pig to that reported in the literature for human hypertrophic scar further validating this animal model. NO production is quite different after deep wounds as compared to superficial wounds in the FRDP. Early elevation in nitric oxide production might account for excessive inflammation in deep wounds that become thick scars in the FRDP. Nitric oxide regulators and effects at early stages of scar formation should be elucidated further and the FRDP appears to be a useful model. 相似文献
6.
7.
Determination of optimal cryoprotectants and procedures for their addition and removal from human spermatozoa 总被引:9,自引:7,他引:9
The objective was to test the hypothesis that the optimal cryoprotective
agent for cryopreservation of human spermatozoa would be a solute for which
cells have the highest plasma membrane permeability, resulting in the least
amount of volume excursion during its addition and removal. To test this
hypothesis, theoretical simulations were performed using membrane
permeability coefficients to predict optimal procedures for the addition
and removal of a cryoprotectant. Simulations were performed using data from
four different cryoprotectants: (i) glycerol, (ii) dimethyl sulphoxide,
(iii) propylene glycol and (iv) ethylene glycol. Thermodynamic formulations
were applied to determine approaches for the addition and removal of 1 M
and 2 M final concentrations of cryoprotectant, allowing the spermatozoa to
maintain a cell volume within their osmotic tolerance limits. Based on
these data, ethylene glycol was predicted to be optimal for minimizing
volume excursions among the solutes evaluated. These predictions were then
experimentally tested using glycerol as the control cryoprotectant and
ethylene glycol as the experimental cryoprotectant. The results indicate
that there was a higher (P < 0.05) recovery of motile spermatozoa after
cryopreservation when using 1 M ethylene glycol than with 1 M glycerol,
supporting the hypothesis that use of the cryoprotectant for which the cell
has the highest permeability will result in higher cell survival.
相似文献
8.
P Rakoczy T Demeter L Hutchinson G F Sterrett E C Pixley J K Kulski 《Journal of virological methods》1989,25(3):325-336
The potential of using a chemically synthesized oligodeoxynucleotide as a diagnostic probe to detect human papillomavirus type 16 (HPV-16) in genital infections was evaluated by comparing it with a cloned full-length HPV-16 probe in dot-blot DNA hybridizations. An oligonucleotide sequence, 20 bases in length from the E6 region of HPV-16 (E6 oligo) and different from the DNA sequences of HPV types 6, 11 and 18 by at least 2 base pairs, was chosen for chemical synthesis. The oligoprobe, which was 5'-end labelled with [32P]dATP, was found to be specific, but approximately ten times less sensitive than the full-length radiolabelled probe of HPV-16, in dot-blot hybridizations with the DNA of HPV-6, -11, -16 and -18, HPV positive and negative cell-lines. From 36 cervical or vulval scrapes two samples were found positive with both cloned HPV-16 and oligoprobe hybridization. Of 21 samples of formalin-fixed, paraffin-embedded squamous cell carcinomas originating from anus, oesophagus, penis, colon, breast and skin only 4 anal squamous cell carcinomas were positives when hybridized with cloned HPV-16 DNA or with the oligoprobe. This study confirms that HPV-16, which is frequently associated with squamous cell carcinoma of the cervix is also strongly associated with squamous cell carcinoma of the anus. 相似文献
9.
Shichi D Kikkawa EF Ota M Katsuyama Y Kimura A Matsumori A Kulski JK Naruse TK Inoko H 《Tissue antigens》2005,66(3):200-208
Cardiomyopathy is a heart muscle disease with impaired stretch response that can result in severe heart failure and sudden death. A small proportion of hepatitis C virus (HCV)-infected patients may be predisposed to develop dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM). The molecular mechanisms involved in the predisposition remain unknown due in part to the lack of information on their genetic background. Because the human leukocyte antigen (HLA) region has a pivotal role in controlling the susceptibility to HCV-induced liver disease, we hypothesized that particular HLA alleles and/or non-HLA gene alleles within the human major histocompatibility complex (MHC) genomic region might control the predisposition to HCV-associated DCM (HCV-DCM) and/or HCV-associated HCM (HCV-HCM). Here, we present mapping results of the MHC-related susceptibility gene locus for HCV-associated cardiomyopathy by analyzing microsatellite and single nucleotide polymorphism markers. To delineate the susceptibility locus, we genotyped 44 polymorphic markers scattered across the entire MHC region in a total of 59 patients (21 HCV-DCM and 38 HCV-HCM) and 120 controls. We mapped HCV-DCM susceptibility to a non-HLA gene locus spanning from NFKBIL1 to MICA gene loci within the MHC class III-class I boundary region. Our results showed that HCV-DCM was more strongly associated with alleles of the non-HLA genes rather than the HLA genes themselves. In addition, no significant association was found between the MHC markers and HCV-HCM. This marked difference in the MHC-related disease susceptibility for HCV- associated cardiomyopathy strongly suggests that the development of HCV- DCM and HCV-HCM is under the control of different pathogenic mechanisms. 相似文献
10.
D. S. Dunn A. V. Romphruk C. Leelayuwat M. Bellgard J. K. Kulski 《Annals of human genetics》2005,69(4):364-372
Polymorphic Alu insertions (POALINs) are known to contribute to the strong polymorphic nature of the Major Histocompatibility Complex (MHC). Previous population studies on MHC POALINs were limited to only Australian Caucasians and Japanese. Here, we report on the individual insertion frequency of the five POALINs within the MHC class I region, their HLA‐A and ‐B associations, and the three and four locus alpha block POALIN haplotype frequencies in the Northeastern (NE) Thai population. Of the five POALINs, the lowest frequency was 0.018 for AluyHF and the highest frequency was 0.292 for AluyHJ and AluyHG. The strongest positive associations between the POALINs and HLA class I alleles was between AluyMICB and HLA‐B*57, AluyHJ and HLA‐A*24 and HLA‐A*01, and AluyHG and HLA‐A*02, supporting previous findings in Caucasians and Japanese. Single POALIN haplotypes were found more frequently than multiple POALIN haplotypes. However, of the seven different POALIN haplotypes within the MHC alpha block, there were only two significant differences between the NE Thais, Caucasians and Japanese. This study confirms that the MHC POALINs are in linkage disequilibrium with HLA‐A and –B alleles and that there are significant frequency differences for some of the POALINs when compared between NE Thai, Caucasians and Japanese. 相似文献