Human fibrinogen polymorphic site analysis by restriction endonuclease digestion and allele-specific polymerase chain reaction amplification: identification of polymorphisms at positions A alpha 312 and B beta 448

In the fibrinogen molecule, a total of seven sites have been tentatively identified as polymorphic; however, disagreements about these sites have been observed among the various protein and DNA sequence data published. To allow examination of the potential polymorphic sites at the DNA level, human genomic DNA samples were prepared from 110 unrelated, healthy individuals. Either allele- specific polymerase chain reaction (ASPCR) amplification or PCR amplification followed by restriction endonuclease digestion was used to detect the presence of possible polymorphisms. Two polymorphic sites were confirmed, one at A alpha 312 (Thr/Ala) by RsaI restriction analysis, and a second at B beta 448 (Arg/Lys) by MnlI restriction analysis. Mendelian inheritance of both polymorphisms was demonstrated and allele frequencies were estimated as 0.76/0.24 and 0.85/0.15 for the A alpha 312 and B beta 448 sites, respectively. The sites at A alpha 47, A alpha 296, B beta 162, B beta 296, and gamma 88 showed no evidence of variation in any of our samples. The amino acid polymorphisms at A alpha 312 and B beta 448 reflect conservative residue changes with unknown effects on fibrinogen structure or function. An additional, previously unrecognized DNA sequence variant was detected in a single individual in the second intron of the A alpha chain using HinfI restriction analysis.     

应用微电极阵列记录技术研究抑郁大鼠整体心脏心肌电生理特性

目的研究慢性应激对抑郁大鼠心房、心室场电位时程(FAPD)的影响。方法随机将20只大鼠分为对照组、抑郁组,对抑郁组大鼠进行连续21天的慢性应激。应用微电极阵列技术(MEA)记录心房、心室肌场电位波形、心房、心室FAPD。结果抑郁组大鼠慢性应激后的糖水消耗试验、自主活动得分均明显低于对照组(P<0.01)。MEA记录技术可以记录到60个位点心房、心室肌FAPD不同的波形;抑郁组大鼠心房FAPD高于对照组(83.14±4.61msvs45.76±3.66ms,P<0.05)。两组心室肌FAPD无差异。结论慢性应激所致的抑郁可明显延长大鼠心房FAPD,这可能是抑郁导致心律失常的机制之一。     

Sucrose ingestion elicits reduced Fos expression in the nucleus accumbens of anhedonic rats

Chronic mild stress (CMS), an animal model of depression associated with anhedonia, was used to examine nucleus accumbens (NAc) activation associated with a rewarding stimulus. Following 4 weeks of CMS in rats, NAc Fos-immunoreactivity was measured after ingestion of a fixed volume of sucrose. Fewer Fos-positive neurons were observed in the NAc in CMS versus control rats. These findings have implications for the mechanisms underlying reduced responding to pleasurable stimuli associated with depression.