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101.
Cerebral blood flow relationships associated with a difficult tone recognition task in trained normal volunteers 总被引:2,自引:2,他引:0
Holcomb HH; Medoff DR; Caudill PJ; Zhao Z; Lahti AC; Dannals RF; Tamminga CA 《Cerebral cortex (New York, N.Y. : 1991)》1998,8(6):534-542
Tone recognition is partially subserved by neural activity in the right
frontal and primary auditory cortices. First we determined the brain areas
associated with tone perception and recognition. This study then examined
how regional cerebral blood flow (rCBF) in these and other brain regions
correlates with the behavioral characteristics of a difficult tone
recognition task. rCBF changes were assessed using H2(15)O positron
emission tomography. Subtraction procedures were used to localize
significant change regions and correlational analyses were applied to
determine how response times (RT) predicted rCBF patterns. Twelve trained
normal volunteers were studied in three conditions: REST, sensory motor
control (SMC) and decision (DEC). The SMC-REST contrast revealed bilateral
activation of primary auditory cortices, cerebellum and bilateral inferior
frontal gyri. DEC-SMC produced significant clusters in the right middle and
inferior frontal gyri, insula and claustrum; the anterior cingulate gyrus
and supplementary motor area; the left insula/claustrum; and the left
cerebellum. Correlational analyses, RT versus rCBF from DEC scans, showed a
positive correlation in right inferior and middle frontal cortex; rCBF in
bilateral auditory cortices and cerebellum exhibited significant negative
correlations with RT These changes suggest that neural activity in the
right frontal, superior temporal and cerebellar regions shifts back and
forth in magnitude depending on whether tone recognition RT is relatively
fast or slow, during a difficult, accurate assessment.
相似文献
102.
Comparison of nucleic acid hybridization and nucleic acid amplification using conserved sequences from the 5' noncoding region for detection of bovine viral diarrhea virus. 总被引:2,自引:1,他引:1 下载免费PDF全文
Primers and probes derived from conserved sequences located in the 5' noncoding region of pestiviruses were evaluated for detection of bovine viral diarrhea virus. With these reagents, hybridization and polymerase chain reaction tests detected 62 of 90 and 90 of 90 bovine viral diarrhea virus isolates, respectively. A quick lysis method for preparing RNA for use in polymerase chain reaction amplification also was evaluated. 相似文献
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AM Gardier I. Malagié AC Trillat C. Jacquot and F. Artigas 《Fundamental & clinical pharmacology》1996,10(1):16-27
Summary— Although a new generation of selective serotonin reuptake inhibitors (SSRIs) has been introduced in therapeutics as antidepressant drugs, a two to four week lag period still occurs between starting treatment with SSRIs and the onset of therapeutic effects in man. In vivo cerebral microdialysis can be used to measure extracellular concentrations of serotonin (5-hydroxytryptamine, 5-HT), which reflect intrasynaptic events. With the coupling of this new experimental method to very sensitive analytical assays such as liquid chromatography with electrochemical detection, it has recently been possible to obtain two major arguments supporting the hypothesis that somatodendritic 5-HT1A autoreceptors situated in the raphe nuclei play an important role in the mechanism of action of SSRIs. First, in the rat, single administration of SSRIs at low doses comparable to those used therapeutically increases extracellular 5-HT concentrations in the vicinity of the cell body and the dendrites of serotoninergic neurones of the raphe nuclei. This effect is more marked than that observed in regions rich in nerve endings (frontal cortex). The magnitude of the activation of the serotoninergic neurotransmission depends on the brain area studied and the dose of the SSRIs administered to rats. This could be explained by simultaneous activation of somatodendritic 5-HT1A autoreceptors by endogenous 5-HT in the raphe nuclei, thereby limiting the corticofrontal effects of the antidepressant. Second, SSRIs cause a larger increase in extracellular 5-HT concentrations in the nerve endings when administered chronically: 5-HT autoreceptors may have gradually desensitized during the 2–4 weeks of treatment with SSRIs. Preliminary studies of patients with depression appear to confirm these experimental results, as co-administration of a 5-HT1A autoreceptor antagonist and a SSRI accelerated the onset of the antidepressant effect (< 1 week). 相似文献
106.
WSA Smellie MRCP MRCPath D Sandler MB ChB MRCP J O'Donnell MB ChB MRCPath AC Maccuish MD FRCP 《International journal of clinical practice》1995,49(2):83-85
SUMMARY This report presents experiences in screening 350 non-insulin-dependent diabetics for hypercholesterolemia and results of 1 year's treatment. Mean serum total cholesterol was 6.4 mmol/l at screening; 46 patients whose initial total serum cholesterol was above 7.0 mmol/l attended for detailed assessment and treatment. Mean total cholesterol concentrations fell between screening and review (7.8 vs 7.1 mmol/l, P<0.01). Levels fell below 7.0 mmol/l in 13 patients with diet alone. After excluding patients with secondary dyslipidaemia (including poor diabetic control), 10 patients received lipid-lowering drug treatment. Total cholesterol and triglyceride concentrations fell significantly and the HDL/non- HDL cholesterol ratio improved on treatment. Screening diabetic patients identifies a small group of hyperlipidaemic patients, whose lipoprotein profiles improve with drug treatment. Many of those screened, however, do not ultimately require drug treatment using a cut-off of 7.0 mmol/l. 相似文献
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SUMMARY Hypertension is a major risk factor for premature death. Large outcome studies have demonstrated reduced morbidity and mortality associated with antihypertensive therapy in mixed patient populations, but data on morbidity and mortality in defined ethnic groups are lacking. Management of cardiovascular risk factors, which frequently coexist with hypertension, presents a logical management strategy in these patients. Indo-Asian patients are particularly prone to insulin resistance and non-insulin-dependent diabetes mellitus (NIDDM), which are associated in turn with potentially atherogenic lipid profiles and poor cardiovascular outcomes. Diuretics and β-adrenoceptor blockers exert theoretically adverse effects on lipid profiles and should be used with caution in Indo-Asian patients at risk of developing NIDDM. Hypertensive African-Caribbean patients are at increased risk of stroke and tend to suffer greater target organ damage, including renal dysfunction and cardiac hypertrophy. Hypertension in African-Caribbean patients is less sensitive to β-adrenoceptor blockade or ACE inhibition than in white patients. Selective α1-adrenoceptor antagonists and calcium channel blockers are equally effective antihypertensive agents in all races. While calcium channel blockers are metabolically neutral, α1-adrenoceptor blockers promote a potentially less atherogenic lipid profile. Further study of the effects of antihypertensive treatment on morbidity and mortality in ethnic groups is required, particularly in Indo-Asian patients. 相似文献
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