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991.
The reliability of information about mothers' and fathers' education, weight and height at birth, history of diarrhoea, duration of exclusive breast feeding and age of introduction of cows' milk products, selected from a structured questionnaire used in home interviewers was examined in a sample of 38 cases and 38 controls from a study related to the risk factors of insulin-dependent diabetes mellitus. The repetition of the questions was done by telephone. The agreement between the answers of both interviewers was verified using the kappa statistic (categorical variables) and the intra-class correlation coefficient (quantitative variables). The results enable one to conclude that the information is reproducible. 相似文献
992.
Dynamic cardiac SPECT and PET can be used to measure myocardial perfusion by estimating the kinetic rate constant describing the washing of radioactive-labelled tracers from the blood to the extravascular myocardial tissue. Because of differences in photon statistics and data acquisition techniques, protocols which produce optimal estimates of the washin for dynamic cardiac PET may give suboptimal estimates if applied in dynamic cardiac SPECT. Two important factors in the estimation of washin are the shape of the tracer input function and the image acquisition interval. This study uses computer simulations to investigate the effect of varying the tracer infusion length and image acquisition interval on the bias and variance of estimates of washin obtained with dynamic cardiac SPECT and 99mTc-labelled teboroxime. Bias in parameter estimates can be introduced by aliasing, integration of the time-varying radioactivity by the detector, and detector motion. This bias can be reduced by decreasing the acquisition interval and using a longer-duration input function. However, this results in poor photon statistics, which generate large variance, and can also introduce bias in the estimates of the washin. Our studies indicate that better estimates of the washin are obtained by using an acquisition interval that is of sufficient duration to obtain adequate photon statistics even if this is at the expense of temporal resolution. The increase in bias caused by using a 10 or 20 s acquisition interval instead of a 5 s acquisition interval is minimal when compared with the reduction in variance. Variance in estimates is also reduced by using a sharp input function, resulting in higher peak counts during washin. It is also shown that the variance of estimates of the washin increases generally when faster kinetics are observed. This variance can, however, be reduced by using longer acquisition intervals. 相似文献
993.
An experimental study was undertaken in dogs with carbon tetrachloride (CCl4) intoxication to describe and follow the changes in the ultrasound appearance of the liver. Characteristic ultrasound features (enlarged liver, increased echogenicity with fine, tightly-packed echoes, and loss of echogenicity of the portal vein walls) were seen from day 2 of the experiment, culminating between days 2 and 7. Subsequently the liver gradually and almost completely regained its normal ultrasound appearance. Ultrasonographic findings corresponded to the severity of the clinicopathological parameters, and changed parallel with the results of liver biopsies. Histology of the biopsy samples revealed acute centrolobular lipid accumulation with necrobiosis and necrosis in the hepatocytes in the first stage of the disease. In the second stage, a secondary reparatory-inflammatory process and reparation in the interstitial tissue were seen. In some dogs, ill-defined hyperechoic foci were observed within the liver during the regenerative phase. Hepatic ultrasonography seems to be a reliable and relatively sensitive method for monitoring liver dystrophy with necrobiosis and lipid accumulation and to follow the course of steatosis in clinical cases. Ultrasound-guided biopsy can further improve the diagnostic accuracy of ultrasonography in liver dystrophy. 相似文献
994.
E Buratti SG Tisminetzky P D'Agaro FE Baralle 《Canadian Metallurgical Quarterly》1997,71(3):2457-2462
We report here that a human immunodeficiency virus type 1 (HIV-1)-specific neutralizing monoclonal antibody (MAb 1575) mapped to the conserved putative intracellular region from amino acid residues 735 to 752 (735-752 region) of gp41 also recognizes a region in an extracellular portion of p17. Both epitopes have a core recognition sequence (IEEE) in a nonhomologous context. The IEEE motif found in HIV-1 p17 is located in a region known as HGP-30 (residues 86 to 115) which has been previously associated with virus neutralization, cytotoxic T lymphocyte activity, and mother-to-child transmission. An analysis of available gp41 and p17 sequences demonstrates that in these regions both IEEE sequences are highly conserved in different HIV-1 clades. The presence of the IEEE epitope in p17 allows us to explain some unexpected neutralizing characteristics of MAb 1575. In addition, the gp41 735-752 region has been previously reported both in intra- and extracellular locations. Our results suggest that the extracellular location was the result of cross-reactivity with p17. 相似文献
995.
NJ Cherepy AP Shreve LJ Moore SG Boxer RA Mathies 《Canadian Metallurgical Quarterly》1997,36(28):8559-8566
Qy-excited resonance Raman spectra of the accessory bacteriochlorophylls (B), the bacteriopheophytins (H), and the primary electron donor (P) in the bacterial photosynthetic reaction center (RC) of Rhodobacter sphaeroides have been obtained at 95 and 278 K. Frequency and intensity differences are observed in the low-frequency region of the P vibrational spectrum when the sample is cooled from 278 to 95 K. The B and H spectra exhibit minimal changes of frequencies and relative intensities as a function of temperature. The mode patterns in the Raman spectra of B and H differ very little from Raman spectra of the chromophores in vitro. The Raman scattering cross sections of B and H are 6-7 times larger than those for analogous modes of P at 278 K. The cross sections of B and of H are 3-4 times larger at 95 K than at 278 K, while the cross sections of P are approximately constant with temperature. The temperature dependence of the Raman cross sections for B and H suggests that pure dephasing arising from coupling to low-frequency solvent/protein modes is important in the damping of their excited states. The weak Raman cross sections of the special pair suggest that the excited state of P is damped by very rapid (<30 fs) electronic relaxation processes. These resonance Raman spectra provide information for developing multimode vibronic models of the excited-state structure and dynamics of the chromophores in the RC. 相似文献
996.
997.
JJ Kolkman TH Falke JC Roos DH Van Dijk IM Bannink W Den Hollander MA Cuesta AS Pe?a SG Meuwissen 《Canadian Metallurgical Quarterly》1996,41(4):641-650
The accuracy of computed tomography (CT) and [99mTc]HMPAO granulocyte scintigraphy (GS) for detection of bowel localization, inflammatory activity, and complications in acute inflammatory bowel disease (IBD) was prospectively studied in 32 patients. Of each bowel segment, findings on CT and GS were scored by one blinded observer. Findings on operation or endoscopy served as the gold standard. In Crohn's disease (CD, 17 patients), CT detected bowel pathology (sensitivity 71%, specificity 98%), abscesses (sensitivity and specificity 100%), and fistulas (sensitivity 80%, specificity 100%). In CD, GS had a sensitive of 79% and a specificity of 98% for detection of inflammatory activity. The detection of complications with GS was poor. Segmental inflammatory activity correlated with endoscopy-operative findings for CT (r = 0/86, P < 0.0001) and GS (r = 0.86, P < 0.0001). In ulcerative colitis (UC, 15 patients), GS predicted proximal extension of bowel involvement better than CT. In CD, CT is Superior to GS for localization of both active and fibrostenotic bowel disease, and in detection of the abscesses and fistulas. In UC, GS showed proximal extension more accurately than CT. 相似文献
998.
999.
We developed an immunochromatographic whole-blood test (WBT) which detects antibodies to human immunodeficiency virus types 1 and 2 (HIV-1 and HIV-2) from fingerstick blood. The sensitivity and specificity of the WBT were 99.41% (1,018 confirmed positive patients) and 99.89% (941 uninfected patients), respectively (enzyme immunoassay [EIA] on serum or plasma as a reference). WBT performance was comparable to those of licensed EIAs and Western blotting, using 18 HIV-2 sera, 23 HIV-1 seroconversion panels, and a low-titer performance panel (in lieu of whole blood). 相似文献