Frequency-dependence of myocardial energetics in failing human myocardium as quantified by a new method for the measurement of oxygen consumption in muscle strip preparations

Diastolic dysfunction at high heart rates may be associated with increased myocardial energy consumption. Frequency-dependent changes of isometric force and oxygen consumption (MVO2) were investigated in strip preparations from endstage failing human hearts exhibiting various degrees of diastolic dysfunction. MVO2 was determined by a new method which was validated. When stimulation rate was increased from 40 to 200 min-1 (n=7), developed force decreased from 16.5+/-4.3 to 7.9+/-2.9 mN/mm2 (P<0.01), diastolic force increased from 15.9+/-3.2 to 22.0+/-3.0 mN/mm2 (P<0.01), and total MVO2 increased from 2.6+/-0.6 to 4.7+/-0.9 ml/min/100 g (P<0.025). Resting MVO2 and resting force were 1.8+/-0.4 ml/min/100 g and 15.9+/-3.0 mN/mm2, respectively. After addition of 30 mm 2,3-butanedione monoxime (BDM) to inhibit crossbridges, resting MVO2 and resting force decreased by 46% (P<0.05) and 15% (P<0.01), respectively, indicating the presence of active force generation in unstimulated failing human myocardium. In each muscle preparation, there was a significant correlation between force-time integral (FTI) and total MVO2 (r=0.96+/-0.01). The strength of these correlations did not vary with the contribution of diastolic FTI to total FTI. The ratio of activity related MVO2 to developed FTI, an inverse index of the economy of contraction, increased depending on the rise of diastolic FTI at higher stimulation rates. In conclusion, in failing human myocardium, diastolic force development is occurring at the same energy expenditure as systolic force generation. Therefore, in muscle preparations with disturbed diastolic function economy of contraction decreases with higher stimulation rates, depending on the rise of diastolic force.     

Determination of the viremia threshold for dental cross-infection in a mouse model

An animal model of dental virus transmission was developed using the lactate dehydrogenase-elevating virus (LDV) of mice to study cross infection. Mouse-to-mouse cross-infection was carried out by scaling the teeth of LDV-infected donor mice with dental instruments, immediately prior to using the contaminated instruments on the teeth of recipient indicator mice. The level of donor viremia was found to correlate with the rate of virus cross-infection, with a viremia threshold level of 10(7.5) ID50/ml observed for dental cross-infection. The blood volume transferred during dental cross-infection was approximately 10(-4) to 10(-5) ml, demonstrating the inefficiency of virus cross-infection, since deposition of about 1000 virions on dental instruments was associated with the threshold limit. Virus transferred during dental cross-infection rapidly entered the blood circulation, showing that dental cross-infection was not dependent on an oral infection. The results from these model studies predict the general inefficiency of dental instrument virus cross-infection, and a further reduced likelihood of dental cross-infection with appropriately cleaned instruments.     

Identification of domains involved in superantigenicity of streptococcal pyrogenic exotoxin F (SpeF)

Coronary artery angioplasty or bypass is being performed for increasing numbers of patients in their seventh, eighth, ninth and even tenth decades of life. Because of the cost involved, justification for performing these procedures in the elderly has become a topic of daily discussion among those responsible for funding healthcare. Both silent and overt coronary artery disease (CAD) are more common in the population over 65 years of age. Because CAD in the elderly often presents in an atypical manner, diagnosis of the disease is frequently delayed. Partly because of the delayed diagnosis and partly because of cost considerations, coronary arterial bypass (CABG) is more often performed as an emergency procedure in the elderly with the results that both operative mortality and costs are increased over those observed in a younger population. Nevertheless, it is clear that performance of coronary revascularization procedures in the elderly can both prolong life and improve the quality of life beyond what can be achieved using alternative methods of treatment. Greater efforts directed toward detection of ischemic heart disease in the these patients and earlier, elective surgery could significantly reduce both the mortality and disability associated with CAD in the elderly.     

Does oral experience terminate ingestion?

Using data from studies of ingestive behavior in developing rat pups we demonstrate how oral experience can contribute to the termination of ingestion. In rat pups, repeated oral stimulation with sweet solutions causes a decline in oral responsiveness. The diminished responsiveness is specific to the flavor of the stimulus experienced orally and can persist for several hours. We suggest that this experience-based decrement in responsiveness is best considered "oral habituation" and that oral habituation largely accounts for the onset of satiety. Post-ingestive feedback signals may have their influence through the oral habituation process or act in the context of oral habituation. Oral habituation is also shown to depend on the pattern of stimulus presentation, a phenomenon that adds considerable complexity to assessing the contributions of oral experience to satiety. The concept of oral habituation may be useful in understanding the immediate control of ingestion and the moment-to-moment expression of ingestive behavior in adult animals.     

Characteristic Anthocyanin Pattern from Onions and other Allium spp

Three red onion (Allium cepa) cultivars, top onion (A. cepa var. vivi-parum), A. altaicum and chive (A. schoenoprasum) contained several or all of the following anthocyanins: 3-(6′-malonyl-3′-glucosylglucoside), 3-(3′,6′-dimalonylglucoside), 3-(6′-malonylglucoside), 3-(3′-malonyl-glucoside), 3-(3′-glucosylglucoside) and 3-glucoside of cyanidin. Trace amounts of two pelargonidin derivatives and the 3,5-diglucosides of cyanidin and peonidin were for the first time reported in red onion. Carbon NMR data showed that the sugars of the 3-(6′-malonyl-3′-glu-cosylglucoside), 3-(6′-malonylglucoside) and 3-glucoside of cyanidin were pyranoses. Substitution either by sugar or acid in the sugar 3-position of an anthocyanin has never been reported outside the genus Allium.     

网络存储的发展历程及新兴的iSCSI

目前SAN和NAS存储正在迅速发展，DAS的生存空间越来越小。今天超过1／3的存储是网络化的，如果不是因为FC的高成本和复杂性．这个数字还会更大。iSCSI是IETF一种新的标准协议．它将SCSI命令压缩到TCP／IP包．使数据块在IP网络上传播。和FC-SAN相比．高速千兆iSCSI耙SCSI、以太网和TCP／IP结合起来，具有许多优势．如建立在稳定和熟悉的标准上；较低的总拥有成本，安装和维修费用很低；较高程度的可操作性，减少了异构网络和电缆．使用一般的以太网交换机而不是特殊的FC交换机；等等。