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排序方式: 共有701条查询结果,搜索用时 15 毫秒
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Guanine nucleotide-binding protein-coupled receptors have been shown to exist in both a high affinity agonist (HiAg) and a low affinity agonist (LowAg) state. The formation of the HiAg state is promoted by agonists, and the formation of this state of the receptor appears to be a critical factor in the generation of the effector-activating complex G alpha.GTP.Mg2+ and in the production of a stimulus. The magnitude of the difference in the affinity a compound has for the HiAg versus the LowAg state of the receptor has been related to the intrinsic activity of the compound. In this paper the HiAg and LowAg affinities (Ki) of full and partial dopamine agonists of varying levels of intrinsic activity were determined using membranes from Chinese hamster ovary cells stably transfected with the D2i receptor. The HiAg state was defined using the recently described dopamine agonist ligand [3H]U-86170, and the LowAg state was defined using [3H] raclopride plus 600 microM GTP. The LowAg/HiAg ratios for apomorphine (43), HW-165 (12.5), (-)-3-(3-hydroxyphenyl)-N-(1-propyl)piperidine [(-)-3-PPP] (4.5), terguride (1.6), SDZ-208-911 (1.2), and SDZ-208-912 (0.3) were found to correlate well with their electrophysiologically derived intrinsic activities (r = 0.92). Using this relationship, the intrinsic activity for compounds such as (+)-3-PPP (112%), quinpirole (104%), U-68553B (102%), and U-86170 (95%) was predicted to be high (greater than 90%); (-)-apomorphine (73%) was of high/moderate intrinsic activity, HW-165 (52%), (+)-apomorphine (51%), and (-)-3-PPP (34%) were in the intermediate range, and terguride (16.5%), SDZ-208-911 (11.7%), and SDZ-208-912 (-12%) were at the lower end of the intrinsic activity spectrum. The receptor state binding-determined intrinsic activity values for quinpirole (100%), U-86170F (94.8%), HW-165 (52.1%), (-)-3-PPP (34.3%), SDZ-208-911 (11.7%), and SDZ-208-912 (-12%) were found to correlate well (r = 0.908) with their maximum response (intrinsic activity), as determined using ATP-mediated increases in arachidonic acid release from CHO-D2i cells. In addition, the maximal effect of several of these compounds on rat striatal homovanillic acid (HVA) levels was determined. The drug-induced changes in tissue HVA levels were found to be consistent with the affinity-derived intrinsic activities of the drugs.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
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Bals-Pratsch M; De Geyter C; Muller T; Frieling U; Lerchl A; Pirke KM; Hanker JP; Becker-Carus C; Nieschlag E 《Human reproduction (Oxford, England)》1997,12(5):896-904
Preliminary data have suggested that female infertility due to corpus
luteum insufficiency may be caused by subclinical hypothyroidism
[exaggerated thyroid-stimulating hormone (TSH) response to thyrotrophin-
releasing hormone (TRH) stimulation]. L-Thyroxine supplementation has been
recommended to achieve pregnancies in subclinical hypothyroid women. This
controlled study was carried out in order to investigate the biochemical
diagnosis of subclinical hypothyroidism as a possible infertility factor.
Five infertile patients (aged 25-36 years) with subclinical hypothyroidism
(n = 4, stimulated TSH >20 microU/ml) or primary hypothyroidism (n = 1)
and five healthy controls (aged 22-39 years) with normal thyroid function
(stimulated TSH <15 microU/ml), regular cycles and no history of
infertility were studied in the early follicular phase. In the pre-study
evaluation, eight of 23 volunteers (34.8%) had to be excluded because of
subclinical hypothyroidism with stimulated TSH values (TSHs) >15
microU/ml. Cycle function of patients and controls was compared by the
method of LH pulse pattern analysis. Therefore blood samples were drawn
every 10 min during a 24 h period. Sleep was recorded from midnight to 7
a.m. Repetition of the TRH tests at the end of the 24 h blood sampling
period confirmed the difference in stimulated TSH values of the two study
groups. Pulse analysis for luteinizing hormone (LH), TSH and prolactin
showed no differences between patients and controls for pulse frequency,
amplitude, height, length, area under curve (AUC) and the 24 h mean. Even
the hypothyroid patient had a normal LH pulse pattern. Additional
measurement of melatonin in pooled sera every 30 min gave the
well-documented diurnal profiles during day and night for both groups.
Patients had significantly higher melatonin values at seven time points
during the night. Peaks for LH, TSH, prolactin and cortisol were correlated
with the sleep stages wake, rapid eye movement, 1 + 2 and 3 + 4. We
concluded that corpus luteum insufficiency in female infertility cannot be
explained by subclinical hypothyroidism and thus should not be treated with
L-thyroxine for fertility reasons.
相似文献
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KM Kanal NJ Hangiandreou AM Sykes HE Eklund PA Araoz JA Leon BJ Erickson 《Journal of digital imaging》2002,14(1):30-37
The aims of this work were to measure the accuracy of one continuous speech recognition product and dependence on the speaker's
gender and status as a native or nonnative English speaker, and evaluate the product's potential for routine use in transcribing
radiology reports. IBM MedSpeak/Radiology software, version 1.1 was evaluated by 6 speakers. Two were nonnative English speakers,
and 3 were men. Each speaker dictated a set of 12 reports. The reports included neurologic and body imaging examinations performed
with 6 different modalities. The dictated and original report texts were compared, and error rates for overall, significant,
and subtle significant errors were computed. Error rate dependence on modality, native English speaker status, and gender
were evaluated by performing ttests. The overall error rate was 10.3 +/- 3.3%. No difference in accuracy between men and women
was found; however, significant differences were seen for overall and significant errors when comparing native and nonnative
English speakers (P = .009 and P = .008, respectively). The speech recognition software is approximately 90% accurate, and
while practical implementation issues (rather than accuracy) currently limit routine use of this product throughout a radiology
practice, application in niche areas such as the emergency room currently is being pursued. This methodology provides a convenient
way to compare the initial accuracy of different speech recognition products, and changes in accuracy over time, in a detailed
and sensitive manner. 相似文献
10.
Acute porphyria is rare in orientals. We describe a Chinese woman with recurrent generalised tonic-clonic seizures and abdominal pain. Genomic DNA studies identified a heterozygous base substitution from guanine to adenine at nucleotide position 503, resulting in substitution of arginine by histidine at position 168 of the protein (R168H). This genetic abnormality is similar to the mutation reported in Caucasians with variegate porphyria. To the best of our knowledge, this is the first report in the English literature a Chinese patient with variegate porphyria with an identifiable mutation. A brief review of porphyria is presented. 相似文献