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33.
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
34.
Kirsty Brown Patrick FW. Chien Benjie Tang 《Obstetrics, Gynaecology and Reproductive Medicine》2019,29(8):213-218
Surgical technology has advanced to a level where most gynaecological operations can be performed laparoscopically. Performing laparoscopic surgery requires a degree of surgical skill and structured training is required. A mixture of simulation training and supervised clinical training is required to acquire the skills to perform laparoscopic surgery competently. Attending good quality training courses will enhance the required skills and allow practice of these procedures before attempting these procedures on patients. A patient-centred approach should be adopted when counselling patients pre-operatively, particularly when choosing the route of a procedure. Structured training in technical and non-technical skills is essential. 相似文献
35.
M E Larimer A P Turner B K Anderson J S Fader J R Kilmer R S Palmer J M Cronce 《Journal of studies on alcohol》2001,62(3):370-380
OBJECTIVE: The current study tested the efficacy of a brief intervention designed to reduce drinking and drinking-related consequences among first-year fraternity members. METHOD: Twelve fraternities were randomly assigned to receive either a motivational enhancement intervention with individual and housewide feedback components (n = 6 houses) or a treatment-as-usual control condition (n = 6 houses). Individual feedback was delivered either by peer interviewers or professional research staff. Participants were assessed during their pledge (first) year of house membership and during a follow-up period 1 year later. RESULTS: Of the participants who completed follow-up (N = 120), fraternity members who received the brief intervention reported significant reductions in alcohol use (total average consumption) and typical peak blood alcohol concentrations when compared with fraternity members in the control condition. No differences in drinking-related consequences were observed. Fraternity members who received their individualized feedback from peer interviewers and professional members of the research staff reported similar outcomes. CONCLUSIONS: Results provide support for the efficacy of a brief motivational enhancement intervention in reducing drinking within this high-risk population. The cost-effective use of peer interviewers appears to be a promising strategy for delivering individualized prevention programming in college populations. 相似文献
36.
In contrast to the murine system, long-term hamster bone marrow suspension cultures maintain proliferation of both pluripotent and committed stem cells in the absence of an adherent layer and without addition of exogenous factors, such as hydrocortisone. Addition of pokeweed-mitogen-stimulated hamster spleen conditioned medium (SCM) to these long-term suspension cultures produces an increase in the number of mixed colonies assayed in soft-agar, These mixed colonies, which contained four cell lineages--granulocytic, erythroid, megakaryocytic, and macrophage--could be generated from cells grown in suspension for over 6 mo. Addition of SCM also induces an initial rapid expansion of the myeloid compartment, and this expansion results in 70% of the cells being terminally differentiated granulocytes. In contrast, addition of SCM to hamster bone marrow cultures containing both adherent cells and hematopoietic stem cells produced no change in the number of mixed colonies generated in the culture. This system allows the in vitro study of the process of stem cell proliferation and differentiation and also provides a means to examine the relationship of adherent and supernatant bone marrow populations. 相似文献
37.
Invasion of erythrocytes by Plasmodium falciparum malaria parasites: evidence for receptor heterogeneity and two receptors 总被引:19,自引:0,他引:19
Plasmodium falciparum malaria parasites with different capabilities of invading sialic acid-deficient erythrocytes were identified. Thai-2 parasites cultured in Tn erythrocytes invaded neuraminidase-treated and Tn erythrocytes twice as efficiently as Thai-2 parasites cultured in normal erythrocytes and seven to ten times more efficiently than a cloned line of Camp parasites cultured in normal erythrocytes. All three parasite lines required sialic acid for optimal invasion, but Thai-2 parasites cultured in Tn erythrocytes invaded neuraminidase- treated erythrocytes with 45% efficiency whereas Camp parasites invaded neuraminidase-treated erythrocytes with less than 10% efficiency. P falciparum malaria parasites probably possess two receptors: one that binds to a sialic acid-dependent ligand and another that binds to a sialic acid-independent ligand. Parasites may differ in the quantity or affinity of their receptors for the sialic acid-independent ligand. 相似文献
38.
Faltynek CR; Princler GL; Rossio JL; Ruscetti FW; Maluish AE; Abrams PG; Foon KA 《Blood》1986,67(4):1077-1082
Patients with hairy cell leukemia (HCL) and chronic lymphocytic leukemia (CLL) were treated with recombinant interferon alpha A (rIFN- alpha A). The binding of iodinated recombinant interferon-alpha to baseline samples of peripheral blood mononuclear cells (PBMCs) from the leukemia patients was compared with clinical responsiveness to rIFN- alpha A. HCL patients (8/10) responded to rIFN-alpha A therapy, whereas none (0/10) of the CLL patients studied responded. The PBMCs from the eight responsive HCL patients bound approximately twice as much iodinated interferon as the PBMCs from nonresponsive CLL patients. This difference was due to more high-affinity receptors per cell with no difference in the affinity of the interferon-receptor interaction. However, because PBMCs from HCL patients were larger than PBMCs from CLL patients, the cell surface receptor density was similar. The leukemic cells from one of the two nonresponsive HCL patients bound iodinated interferon similarly to the cells from the responsive HCL patients, whereas the leukemic cells from the other nonresponsive HCL patient bound considerably less. The rapidity of response of the HCL patients did not correlate with the level of binding of iodinated interferon. Our results suggest that the absolute number of interferon receptors per cell may be only one of several important parameters in the response to rIFN-alpha A therapy, and that the responsiveness of a particular lymphoproliferative disease or a particular patient to rIFN- alpha A therapy cannot be predicted or explained solely by the degree of interaction between IFN and its cell surface receptor. 相似文献
39.
Nonhomogeneous distribution of leukemia in the bone marrow during minimal residual disease 总被引:2,自引:0,他引:2
In a rat model (BNML) for human acute myelocytic leukemia the distribution of leukemic cells in bone marrow samples from various sites was investigated, using monoclonal antibodies (MoAbs) and flow cytometry. Rats were studied before chemotherapy as well as thereafter, ie, in the "minimal residual disease" (MRD) phase. Bone marrow from different types of bones was analyzed from each animal. Before treatment, the ratio of the measured extreme values (ie, highest/lowest value) for leukemic cell frequencies in bones from individual rats ranged from 3.7 to 11.7. During the MRD phase the ratios of the extremes ranged from a factor of 36 to more than 13,000 from one rat to another. The variability between bones of comparable size was estimated by studying the ribs from each individual animal. Within individuals the extremes differed by a factor of 1.2 to 4.0 before chemotherapy and from 2.4 to greater than 320 after chemotherapy. The variability within the marrow cavity of a single bone was determined by analyzing multiple samples from femoral bones cut into slices. The leukemic cell frequency appeared to vary considerably, ie, before treatment from 1.7 to 7.3 and during MRD from 4 to 28,000. The presented data may contribute to understanding the sometimes conflicting observations in leukemic patients. Improvement of methods for detecting MRD will not automatically lead to a more accurate estimation of the total tumor burden. The reliability of diagnoses based on the analysis of single bone marrow aspirates appears to be highly questionable. 相似文献
40.
High-level expression and purification of a recombinant human erythropoietin produced using a baculovirus vector 总被引:1,自引:0,他引:1
Conditions presently have been established for the high-level expression and simplified purification of recombinant human erythropoietin produced in Spodoptera frugiperda cells. Expression, as mediated by infection with a recombinant baculovirus, was accomplished in suspension culture using reduced levels of serum and media supplements experimentally determined to provide optimum levels of factor production (500,000 U/L). Purification of this recombinant human erythropoietin to virtual homogeneity (greater than or equal to 99%) was accomplished via a simple three-step procedure involving isocratic elution from DEAE-Sephacel, reverse-phase high performance liquid chromatography (HPLC) on a C4 medium, and the single-step elution of purified hormone from concanavalin A agarose. Overall, an 890-fold purification was accomplished with a recovery of 80% as assayed in vitro. Biologically, this purified erythropoietin is highly active, possessing a specific activity in vitro of 200,000 U/mg protein. Chemically, this erythropoietin (molecular weight [mol wt] 26,200) appears exceptionally uniform in its oligosaccharide constitution (30%) as contrasted with heterogeneously glycosylated erythropoietins derived from mammalian cells (mol wt 30,000 to 38,000; 40% to 50% complex-type oligosaccharide). Thus, human erythropoietin as presently produced in an insect cell line comprises not only an abundant source of highly active, readily purified hormone for studies of its mechanism of action and cell surface receptor, but also represents a uniquely homogeneous form that should prove advantageous for direct structural analyses. 相似文献