A method for locating gradual changes in time series.

A variation to the change-point problem is addressed. The classical problem involves locating abrupt changes in the mean value of a signal. In contrast, a generalisation to gradual changes with constant speed is considered, which frequently occurs in biomedical signal-processing tasks. Formulas are derived that are easy to adopt by application scientists. The estimation quality is investigated theoretically and using Monte Carlo simulations. Results show that the change-point estimates were close to their true values. In contrast, a systematic error of approximately half the change duration occurred when the gradual nature of the signal was neglected.     

A portal vein cannulation technique for drug discovery in mice

One approach to understanding how orally administered drugs are absorbed and metabolized involves measuring compound concentrations in portal vein blood and in systemic circulation at various time points. In mice, blood samples are generally collected through terminal bleeding, a process that requires a large number of mice and is susceptible to variation between individuals. The authors developed a portal vein cannulation procedure for serial bleeding in the mouse, using a modified catheter containing a stainless steel stylet that is implanted directly in the portal vein. To demonstrate the technique, they orally administered two different compounds to mice and obtained blood samples from the tail vein and portal vein at different time points. They analyzed compound concentrations using liquid chromatography-tandem mass spectrometry. The technique refines existing methods for pharmacokinetic studies in the mouse and reduces the number of mice required.     

A new modified canine model of portal vein thrombosis

Portal vein thrombosis (PVT) is a common complication of liver cirrhosis. Gao et al. [1] reported that the prevalence of PVT in patients with cirrhosis is 8.82%. With the rapid developments in image-based diagnostic technology, the diagnosis rate of PVT is gradually increasing [2]. A follow-up study of 1243 patients with cirrhosis revealed that the cumulative incidences of PVT at 1, 3, and 5 years are 4.6%, 8.2%, and 10.7%, respectively [3]. PVT is a life-threatening factor for patients with cirrhosis, leading to portal hypertension and aggravating gastrointestinal hemorrhage [4]. The prevention of PVT has become a focus of clinical concern nowadays. It is well known that the establishment of animal models is the basis of scientific research. However, it is currently difficult to establish PVT models in large animals. Thereby, the establishment of a stable PVT animal model to study PVT is urgent and significant. We successfully established a new canine model of PVT involving the injection of an autologous thrombus through an indwelling catheter in the portal vein. This model is reliable for further studies of surgical treatment and drug therapy for PVT.