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排序方式: 共有335条查询结果,搜索用时 31 毫秒
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L. FRØLUND F. MADSEN B. SCHARLING J. H. HEINIG U. GERNER SVENDSEN 《Clinical and experimental allergy》1992,22(2):219-225
This study was designed to investigate if two equivalent doses of allergen administered by different dosing regimes--two breaths and 10 breaths of each concentration--would result in the same magnitude of the early and late asthmatic response. Fifteen patients with extrinsic allergic asthma were challenged twice with either two or 10 breaths of twofold increasing allergen concentrations. The challenge was continued until a 20% decrease in FEV1 had been achieved. A non-cumulative PC20FEV1 allergen was derived, and the cumulative dose of allergen given was similarly derived. In order to assess the reproducibility of the challenge, seven patients were challenged twice with two-breath regime. The mean value of allergen PC20 obtained by the two-breath regime was 4.1 fold (95% CI: 2.3-7.1 fold) greater than those obtained by the 10-breath regime (P less than 0.05), whereas the difference was 1.4 fold (95% CI: -3.3-0.5 fold) for the cumulative dose (P greater than 0.05). A statistically significant larger magnitude of the early asthmatic response, as determined by the maximum per cent fall in FEV1, and late asthmatic response determined by the maximum per cent fall in peak expiratory flow domiciliary recorded during the following 24 hr after challenge, was observed in favour of the 10-breath regime compared to the two-breath regime (mean difference 6%, 95% CI: 0.6-11%). The reproducibility of the provocation test was acceptable (+/- 1.8 two-fold concentration difference). These results confirm the 'equivalent dose hypothesis', and demonstrates that dosage rather than concentration appears to determine the early and late asthmatic response after bronchial allergen challenge. 相似文献
4.
Short-Ti inversion-recovery pulse sequence: analysis and initial experience in cancer imaging 总被引:2,自引:0,他引:2
Inversion recovery (IR), commonly considered a pulse sequence capable of producing T1-weighted images with excellent display of normal anatomy, is versatile: The null point and peak time provide a useful, succinct summary of the properties of IR and its capacity for producing both T1- and T2-weighted images. Shortening of the inversion time (TI) and creation of a short-TI inversion-recovery (STIR) pulse sequence increases sensitivity to malignancy and other abnormalities by making the effects of prolonged T1 and T2 on signal intensity additive and by nulling the signal from fat. The authors examined over 300 patients with various malignancies and compared STIR images with T1- and T2-weighted images obtained at 0.5 T. In 43 cases, signal-difference-to-noise ratios (SD/Ns) were calculated between tumor, fat, and muscle. In general, STIR images demonstrated tumor as a conspicuously high-intensity area in a background of muted, discernible anatomic detail. The good contrast achieved with STIR sequences between tumor and fat (SD/N = 18.1) and tumor and muscle (SD/N = 12.9) consolidated into a single image the information contained separately on T1- and T2-weighted images, which facilitates efficient detection and localization of malignancy. 相似文献
5.
L. FRØLUND F. MADSEN U. G. SVENDSEN N. H. NIELSEN B. WEEKE 《Clinical and experimental allergy》1987,17(3):217-228
Standardized bronchial allergen provocation was performed twice in nineteen extrinsic, well defined, stable asthmatic patients, with an interval of median 15 days (range 14–19) to study the reproducibility of the bronchial response. Smoking and medications were withheld prior to the provocation after a rigid scheme. Ten-fold increasing concentrations of allergen solution 0.9 ml were inhaled by tidal volume breathing for 5 min with intervals of 10 min. The bronchial response to inhaled allergen was determined by forced expiratory volume in the first sec (FEV1) and by total resistance to breathing (Rt) determined by an opening interrupter method. The provocation was continued until an allergen concentration causing at least 20% decrease of the postsaline FEV1 or a 40% increase in Rt was reached. A PC20-FEV1 and a PC40-Rt was calculated by interpolation on the log-dose-response curve. The reproducibility of PC20-FEV1 allergen was high with a 95% confidence interval (CI) for a single determination being the observed value ±0.83, ten-fold concentration difference, the intraclass correlation (IC) was 0.99 and the coefficient of variation 8.46%. Concerning PC40-Rt a 95% CI for a single determination was calculated being the observed value ±0.58, ten-fold concentration difference, IC was 0.99 and the coefficient of variation was 5.79%. No significant correlation was found between differences in pre-challenge FEV1 and Rt values and the corresponding PC20-FEV1 and PC40-Rt values. Least square regression between PC20-FEV1 and PC40-R1 was performed for the first and the second provocation (P < 0.05). We conclude that bronchial allergen challenge performed in stable asthmatics is highly reproducible and as such a valuable test in the diagnosis of allergic asthma when connected with anamnesis, skin-prick test and the level of specific immunoglobulin E in peripheral blood. 相似文献
6.
The effects of antioxidant supplementation during Percoll preparation on human sperm DNA integrity 总被引:20,自引:6,他引:20
Hughes CM; Lewis SE; McKelvey-Martin VJ; Thompson W 《Human reproduction (Oxford, England)》1998,13(5):1240-1247
The integrity of sperm DNA is crucial for the maintenance of genetic
health. A major source of damage is reactive oxygen species (ROS)
generation; therefore, antioxidants may afford protection to sperm DNA. The
objectives of the study were, first, to measure the effects of antioxidant
supplementation in vitro on endogenous DNA damage in spermatozoa using the
single cell gel electrophoresis (comet) assay and, second, to assess the
effect of antioxidant supplementation given prior to X-ray irradiation on
induced DNA damage. Spermatozoa from 150 patients were prepared by Percoll
centrifugation in the presence of ascorbic acid (300, 600 microM), alpha
tocopherol (30, 60 microM), urate (200, 400 microM), or acetyl cysteine (5,
10 microM). DNA damage was induced by 30 Gy X-irradiation. DNA strand
breakage was measured using the comet assay. Sperm DNA was protected from
DNA damage by ascorbic acid (600 microM), alpha tocopherol (30 and 60
microM) and urate (400 microM). These antioxidants provided protection from
subsequent DNA damage by X-ray irradiation. In contrast, acetyl cysteine or
ascorbate and alpha tocopherol together induced further DNA damage.
Supplementation in vitro with the antioxidants ascorbate, urate and alpha
tocopherol separately has beneficial effects for sperm DNA integrity.
相似文献
7.
How to use Chlamydia antibody testing in subfertility patients 总被引:1,自引:9,他引:1
Screening for tubal factor subfertility by means of Chlamydia antibody
testing (CAT) was introduced into the initial work-up of subfertile couples
several years ago. The results reported, however, are heterogeneous, and no
uniformity exists in cut-off levels of titres, or in definitions of tubal
factor subfertility. We performed a prospective cohort study to evaluate
the implications of varying the definitions of tubal pathology and of
modifying the cut-off levels on the clinical impact of CAT in predicting
tubal factor subfertility. In 227 consecutive patients who attended our
fertility clinic, the Chlamydia IgG antibody titre was determined and
related to tuboperitoneal abnormalities at laparoscopy as a reference
standard. According to received operating characteristic (ROC) curve
analysis, a titre of 16 is the optimum cut-off level. Increasing the
cut-off level improves specificity and positive likelihood ratio (LR+), at
the expense of sensitivity and negative LR (LR-). Changing the definition
of tubal factor subfertility from unspecified tuboperitoneal abnormalities
into extensive adhesions and/or bilateral distal tubal occlusion improves
LR+, LR- and kappa significantly. We conclude that CAT is more accurate in
predicting severe distal tubal pathology than unspecified tuboperitoneal
abnormalities. Although from a statistical point of view a titre of 16 is
the optimum cut-off level, from a clinical point of view 32 or 64 may be
preferable, depending on the aim of screening and the inception cohort.
相似文献
8.
Adrenocortical Toxicity of 3-Methylsulfonyl-DDE in Mice: II. Mitochondrial Changes following Ecologically Relevant Doses 总被引:3,自引:0,他引:3
JONSSON C.-J.; RODRIGUEZ-MARTINEZ H.; LUND B.-O.; BERGMAN A.; BRANDT I. 《Toxicological sciences》1991,16(2):365-374
Transmission electron microscopy was used to characterize earlyultrastructural lesions in the adrenal zona fasciculata of femaleC57BL mice given a single ip injection of the adrenocorticolyticDDT-metabolite 3- methylsulfonyl-DDE (MCSO2-DDE Following 3mg/kg, mitochondrial changes were observed 6 hr after dosing.At 12 and 24 hr the mitochondrial changes were conspicuous,with disorganization and disappearance of central cristae. Atdoses of 6, 12, and 25 mg/kg body wt initial (6 hr) mitochondrialvacuolization was observed, followed by disappearance of mitochondria(612 mg/kg) or cellular necrosis (25 mg/kg). The metabolicactivation and binding of MeSO2-[14C]DDE in adrenal homogenateswere determined in vitro. The irreversible binding of MeSO2-[14C]to the mitochondria-containing adrenal S-9 pellet fraction was50 times higher than that to the postmitochondrial S-12 supernatantfraction. The apparent Km was 2.1 µM and the apparentVmax was 104 pmol/mg protein/30 mm for the binding of MeSO2-[14C]to S-0.3 supernatants. The irreversible protein binding wasinhibited by metyrapone (K1=1 µM) and 11-deoxycorticosterone(K1=3 µM). In conclusion, the adrenal metabolic activationof MeSO2-[14C]DDE is suggested to be mediated by a mitochondrialcytochrome P450 form, presumably P450 (11ß). A primarymitochondrial lesion develops and subsequently leads to degenerationand necrosis of the zona fasciculata. 相似文献
9.
Mika VJ Mustonen Seppo Pyrh?nen Pirkko-Liisa Kellokumpu-Lehtinen 《World journal of clinical oncology》2014,5(3):393-405
Although more widespread screening and routine adjuvant therapy has improved the outcome for breast cancer patients in recent years, there remains considerable scope for improving the efficacy, safety and tolerability of adjuvant therapy in the early stage disease and the treatment of advanced disease. Toremifene is a selective estrogen receptor modifier (SERM) that has been widely used for decades in hormone receptor positive breast cancer both in early and late stage disease. Its efficacy has been well established in nine prospective randomized phase III trials compared to tamoxifen involving more than 5500 patients, as well as in several large uncontrolled and non-randomized studies. Although most studies show therapeutic equivalence between the two SERMs, some show an advantage for toremifene. Several meta-analyses have also confirmed that the efficacy of toremifene is at least as good as that of tamoxifen. In terms of safety and tolerability toremifene is broadly similar to tamoxifen although there is some evidence that toremifene is less likely to cause uterine neoplasms, serious vascular events and it has a more positive effect on serum lipids than does tamoxifen. Toremifene is therefore effective and safe in the treatment of breast cancer. It provides not only a useful therapeutic alternative to tamoxifen, but may bring specific benefits. 相似文献
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