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41.
Greenlee MW; Koessler M; Cornelissen FW; Mergner T 《Cerebral cortex (New York, N.Y. : 1991)》1997,7(3):253-267
Visual discrimination and short-term recognition memory for computer-
generated random patterns were explored in 23 patients with a postsurgical
lesion in one of the cortical hemispheres. Their results are compared with
those of 23 age-matched volunteers. In a same- different forced-choice
discrimination task, d' and log beta (measures of sensitivity and bias), as
well as reaction time (RT) were determined. All participants viewed
patterns defined either by luminance contrast or isoluminant red-green
color contrast, the amplitude of which was adjusted to be 10 times the
respective detection threshold level. Block patterns consisting of a 6 x 6
matrix of light and dark (red and green) checks were randomly configured on
each presentation. They were presented in pairs, randomly in two visual
quadrants for a duration of 200 msec. Three presentation conditions were
used: simultaneous presentation of reference and test stimulus, sequential
presentation with a short delay (interstimulus interval, ISI = 3 s), and
sequential presentation with a long delay (ISI = 6 s). The results indicate
that patients with a lesion in the occipitotemporal cortex, the superior
temporal cortex and the frontal cortex were significantly impaired on both
luminance-contrast and color-contrast pattern discrimination. Patients with
damage in the anterior inferotemporal cortex showed no overall impairment.
The results suggest that performance in visual discrimination and
recognition memory tasks rely on distributed neural processes with more
than one neocortical location.
相似文献
42.
Tamoxifen (TAM) is a nonsteroidal antiestrogenic drug that is widely used for the treatment of estrogen receptor-dependent breast cancer. An increased risk of endometrial cancer in some patients treated with TAM has been linked to the metabolic formation of alpha-hydroxytamoxifen (alpha-OHTAM) and its subsequent sulfation. Alpha-OHTAM has been found to be a substrate for rat and human hydroxysteroid sulfotransferases (STa and SULT2A1, respectively). Since stereochemistry plays an important role in the interactions of hydroxysteroid sulfotransferases with their substrates, we have now investigated the interactions of each of the stereoisomers of alpha-OHTAM with highly purified recombinant STa and SULT2A1. Methods for the preparation of the enantiomers of E- and Z-alpha-OHTAM were developed. When each of the four enantiomers was examined with rat STa, E-(+)-alpha-OHTAM was the only substrate for the enzyme, whereas E-(-)-alpha-OHTAM, Z-(+)-alpha-OHTAM, and Z-(-)-alpha-OHTAM were inhibitors of the sulfation of E-(+)-alpha-OHTAM catalyzed by STa. The dissociation constants for the alpha-OHTAM enantiomers indicated that they bound to STa with similar affinity, but only the E-(+)-enantiomer was a substrate. In contrast to the results obtained with rat hydroxysteroid sulfotransferase STa, all enantiomers of alpha-OHTAM were substrates for the human SULT2A1. Moreover, kcat/Km values with SULT2A1 were higher with the Z enantiomers than with the E enantiomers. As a result of the potential for interconversion of the E and Z geometric isomers upon metabolism, the sulfation of the Z isomers may be of greater concern in human tissues than has been previously assumed. 相似文献
43.
M W Duffel T P Binder L Hosie H A Baden J A Sanders S A Knapp J Baron 《Molecular pharmacology》1991,40(1):36-44
Aryl sulfotransferases catalyze the formation of sulfuric acid esters from a diverse group of endogenous and xenobiotic organic chemicals. The isoenzyme of aryl sulfotransferase in livers of male Sprague-Dawley rats that exhibits the most varied substrate specificity is aryl sulfotransferase IV. A new method for the purification to homogeneity of aryl sulfotransferase IV was developed that, when compared with previously described procedures, provided a greater than 10-fold increase in total yield of enzyme/g of tissue. Homogeneous aryl sulfotransferase IV was used to prepare polyclonal antibodies in male New Zealand White rabbits. Results of immunochemical analyses demonstrated that these antibodies reacted with only a single protein in rat hepatic 100,000 x g supernatant fractions and, further, that the immunoreactive protein had the isoelectric point and subunit molecular mass characteristic of aryl sulfotransferase IV. Immunohistochemical analyses demonstrated that aryl sulfotransferase IV is present in hepatocytes throughout the liver, although centrilobular cells contain a significantly greater (p less than 0.01) amount of aryl sulfotransferase IV than do either midzonal or periportal cells, in which similar levels of the enzyme are found. 相似文献
44.
45.
We examined differences in approaches to HIV-related infection control practices in two university teaching hospitals in the United States and Nigeria. Health care workers (n = 202 in Nigeria and 186 in the USA) responded to a previously validated measure of infection control practices. There were significant differences in the estimated probability of treating a person with HIV disease (higher in USA), and a greater probability of peer ridicule as a way of enforcing group norms on infection control in Nigeria. Peer enforcement of norms was significantly lower in the USA. In both countries, more precautions would be taken if it was known that the patient was HIV infected. Infection control practices were more likely to be followed in the USA compared with Nigeria if they were praised for this activity, if appropriate facilities (sharps containers, gloves, etc.) were nearby, and if they felt that infection control procedures were effective. These data point to the importance of normative social pressures in Nigeria and of knowing the patient is HIV infected in the USA and feeling that infection control procedures are effective ways of avoiding occupational HIV infection. The role of normative pressures and assumptions about HIV infection status as well as cues and availability of facilities for infection control appear to differ between these health care workers in Nigeria and the USA. 相似文献
46.
47.
阿片受体拮抗剂在TNF-α所致体温升高中的作用 总被引:1,自引:0,他引:1
为探索细胞介素TNF-α升体温效应与下丘脑前部、视前区(POAH)中的阿片受体的关系。应用脑神经核团微量注射方法给自由状态下的雄性SD大鼠POAH区微量注射TNF-α致热源。给药前30min分别用通常阿片受体拮抗剂Nal(10~20μg)和特异性阿片受体μ、δ和κ的拮抗剂CTAP(1.0~2.5μg)、NTI(0.25~0.5μg)和nor-BNI(0.1~3μg)对POAH做预处理。结果:单独给TNF-α可致剂量相关的体温升高△T(1℃~1.4℃);经Nal10μg,CTAP1.0μg和NTI0.5μg处理后使TNF-α的升体温效应减弱;用Nal20μg,CTAP2.5μg和NTI0.25μg处理后可完全阻断TNF-α所致的体温升高;nor-BNI(0.1~3μg)对TNF-α的升体温效应无影响。 相似文献
48.
49.
Long-term follow-up of autoantibody profiles in black female lupus patients and clinical comparison with Caucasian and Asian patients 总被引:5,自引:4,他引:1
The aim was to determine whether the autoantibody profile in Black female
lupus patients is associated with clinical subsets, fluctuates over time
and/or reflects disease activity. A clinical comparison with Caucasian and
Asian patients matched for age of onset and disease duration was also
undertaken. Up to seven serial bleeds from Black female lupus patients who
had been followed up for periods of 3.15 yr were tested for antibodies to
Ro/SSA, La SSB. Sm, RNP and ribosomal P using ELISA research assays.
Significant differences in both clinical and serological profiles between
the ethnic groups were found. Varying aspects of disease activity were
linked to anti-DNA (renal, cardiovascular, global score), anti-ribosomal P
(musculoskeletal, haematology) and anti-Sm (general) antibodies. There are
differences in clinical and serological profiles amongst systemic lupus
erythematosus patients of different ethnic origin. However, using the BILAG
system, relatively few antibodies were found to reflect disease activity
accurately in serial measurements.
相似文献
50.