Minimizing macrovessel signal in cerebral perfusion imaging using independent component analysis.

The pronounced susceptibility effect of macrovessels in MR bolus-tracking studies induces spots of artificially high blood flow and volume in perfusion parameter images. These high-intensity regions impede the detection of perfusion changes and lead to elevated perfusion parameters in adjacent tissues. The purpose of this work was to explore postprocessing methods to reduce the influence of macrovessel signal in dynamic MRI. After data reduction was performed with the use of a principal component analysis (PCA), an independent component analysis (ICA) was applied to separate signal components of different compartments. Based on this decomposition, the dynamic time series were reconstructed with minimized contributions of macrovessel signal and noise. The influence of the temporal resolution and signal-to-noise ratio (SNR) of the source data were investigated by means of a simulation study. A region-of-interest (ROI)-based analysis of corrected and uncorrected in vivo data demonstrated that the influence of arteries and veins was reduced at least by 50%, while gray matter (GM) and white matter (WM) tissues were nearly unaffected by the correction process. Hemodynamic parameter images of the cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) were calculated from corrected and uncorrected scans. The corrected parameter images showed a clearly reduced macrovessel signal and an improved perceptibility of microvascular perfusion changes compared to the uncorrected ones.     

Comparison of Simulated and in-Vivo Plasma Levels of Cilastatin Following Intravenous in-Line Drug Administration

The primary objective of this work was to establish a method to simulate the plasma levels of cilastatin, a model drug, following an intravenous in-line delivery scheme. In-vivo data in dogs obtained from this work were used to demonstrate the validity of the proposed approach. The in-line drug delivery system consists of a drug containing device which is placed between a large volume parenteral and a patient. Numerous advantages have been identified for this automatic in-line reconstitution delivery system. The numerical convolution integral algorithm was used in this work to perform plasma profile simulation. The results indicated that the simulated cilastatin plasma profile following in-line delivery closely agreed with the in-vivo data.     

Cerebral perfusion assessment by bolus tracking using hyperpolarized 13C.

Cerebral perfusion was assessed with 13C MRI in a rat model after intravenous injections of the 13C-labeled compound bis-1,1-(hydroxymethyl)-1-13C-cyclopropane-D8 in aqueous solutions hyperpolarized by dynamic nuclear polarization (DNP). Since the tracer acted as a direct signal source, several of the problems associated with techniques based on traditional dynamic susceptibility contrast (DSC) MRI contrast agents were avoided. Maps of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) were calculated. The MTT was determined to be 2.8 +/- 0.8 sec. However, arterial partial-volume effects in the animal model prevented accurate absolute quantification of CBF and CBV. It was demonstrated that depolarization of the hyperpolarized 13C tracer via relaxation and the imaging sequence had little influence on CBF assessment when the time resolution of the imaging sequence was short compared to the MTT. However, CBV and MTT were increasingly underestimated as MTT or the depolarization rate increased if depolarization was not taken into account. With a modified bolus-tracking theory depolarization could be compensated for, assuming that the depolarization rate was known. Three separate compensation methods were investigated experimentally and by numerical simulations.     

Testosterone in a Cyclodextrin-Containing Formulation: Behavioral and Physiological Effects of Episode-like Pulses in Rats

Testosterone, administered in the form of an inclusion complex with 2-hydroxypropyl--cyclodextrin by subcutaneous injection, enters the circulation in a manner markedly similar to the natural episodic release by the testes. The effects of a regimen of once-a-day administration of complexed testosterone to adult (castrated or intact) rats and to senescent (intact) rats were investigated. Although this procedure left the castrated animals with concentrations of circulatory hormone far below physiological levels for much of the day, a significant improvement in androgen-sensitive behavior and physiology was obtained. Furthermore, the testosterone effects were more pronounced when high doses were used periodically rather than when the same total amount of testosterone was equally divided among doses. The same supplementation to intact rats intensified androgen-sensitive behavior and physiology over normal levels. In senescent rats uniform pulses of the testosterone complex also improved behavior and physiology. Specifically, spermatogenesis was stimulated and, notably, the treatment increased muscle weight without substantial enlargement of the prostate. Since the testosterone–cyclodextrin complex also can be effectively administered as a sublingual tablet, the data suggest that similar regimens may be recommended for elderly men suffering from decreases in muscle mass.     

三种补肾方对老年大鼠下丘神经递质的影响

目的：观察三种补肾方对24个月龄老年大鼠下丘氨基酸类神经递质的影响.方法：采用反相高效液相色谱(HPLC)荧光法、受体放射分析法、RT PCR法测定大鼠下丘的氨基酸递质含量、受体特异性结合量及受体亚单位的mRNA表达.结果：24个月龄大鼠下丘存在兴奋/抑制失衡,表现为下丘γ 氨基丁酸(GABA)能抑制作用减弱,可能与耳鸣发病率随年龄增长而增加有关.补肾息鸣经验方使24个月龄大鼠下丘氨基酸类神经递质介导的抑制作用上调和兴奋作用下调；左归丸及右归丸使24个月龄大鼠下丘兴奋性与抑制性氨基酸类神经递质(Asp、Tau、GABA)含量均有明显上升.结论：对肾虚耳鸣的治疗应在补肾的基础上结合开窍活血等药物.     

丙泊酚及氯胺酮持续泵注与间断静注的静脉全麻比较

目的比较丙泊酚复合氯胺酮静脉泵注与间断静注的静脉全麻效果及安全性。方法　20例ASA　I～II级静脉全麻手术患者随机为I、II组,每组10例,I组为丙泊酚及氯胺酮分次静注组,II组为丙泊酚及氯胺酮持续静脉泵注组。两组术前3分钟静注丙珀酚0.6mg/kg,氯胺酮1mg/kg。I组术中当麻醉转浅时静注丙泊酚(0.6mg/kg)和(或)氯胺酮(1mg/kg),Ⅱ组术中以微泵泵注丙泊酚(1～3mg·kg-1·h-1),氯胺酮(2～4mg·kg-1·h-1)。记录麻醉前至手术进行1小时每隔5分钟测得的平均动脉压(MAP)、呼吸(R)及脉搏氧饱和度(SpO);整个手术过程中麻醉药用量。结果2麻醉期间I组MAP、R波动大,Ⅱ组较平稳;I组有4例SpO下降至88%～94%;Ⅱ组所有病人SpO达98%～100%以上,22两组比较差异有显著性。Ⅱ组人均氯胺酮及丙泊酚用量显著多于Ⅰ组。结论　氯胺酮及丙泊酚微泵泵注给药麻醉效果好,术中BP和R平稳,麻醉药用量少,安全性好。     

Bolus Calculators

Matching meal insulin to carbohydrate intake, blood glucose, and activity level is recommended in type 1 diabetes management. Calculating an appropriate insulin bolus size several times per day is, however, challenging and resource demanding. Accordingly, there is a need for bolus calculators to support patients in insulin treatment decisions. Currently, bolus calculators are available integrated in insulin pumps, as stand-alone devices and in the form of software applications that can be downloaded to, for example, smartphones. Functionality and complexity of bolus calculators vary greatly, and the few handfuls of published bolus calculator studies are heterogeneous with regard to study design, intervention, duration, and outcome measures. Furthermore, many factors unrelated to the specific device affect outcomes from bolus calculator use and therefore bolus calculator study comparisons should be conducted cautiously. Despite these reservations, there seems to be increasing evidence that bolus calculators may improve glycemic control and treatment satisfaction in patients who use the devices actively and as intended.     

恒速滴注法在高龄卧床管饲患者中的应用效果

目的探讨恒速滴注法在高龄卧床管饲患者中的应用效果。方法2010年5月至2011年8月，方便性抽样选择在解放军总医院住院治疗的携带鼻胃管或鼻肠管行胃肠营养的老年患者60例，按入院先后分为观察组和对照组各30例，观察组采用恒速滴注法管饲肠内营养乳剂，对照组采用常规管饲方法即分次推注法，观察并比较两组患者堵管、腹胀、腹泻、反流、误吸等并发症的发生率。结果观察组患者发生堵管、反流及误吸的例数均少于对照组，差异均有统计学意义（均P〈0．05）；发生腹胀与腹泻的例数与对照组比较，差异无统计学意义（均P〉0．05）。结论恒速滴注法肠内营养可有效满足高龄长期卧床患者的营养需求，预防和减少并发症的发生，推荐在临床广泛应用。