KDBI: Kinetic Data of Bio-molecular Interactions database.

Understanding of cellular processes and underlying molecular events requires knowledge about different aspects of molecular interactions, networks of molecules and pathways in addition to the sequence, structure and function of individual molecules involved. Databases of interacting molecules, pathways and related chemical reaction equations have been developed. The kinetic data for these interactions, which is important for mechanistic investigation, quantitative study and simulation of cellular processes and events, is not provided in the existing databases. We introduce a new database of Kinetic Data of Bio-molecular Interactions (KDBI) aimed at providing experimentally determined kinetic data of protein-protein, protein-RNA, protein-DNA, protein-ligand, RNA-ligand, DNA-ligand binding or reaction events described in the literature. KDBI contains information about binding or reaction event, participating molecules (name, synonyms, molecular formula, classification, SWISS-PROT AC or CAS number), binding or reaction equation, kinetic data and related references. The kinetic data is in terms of one or a combination of the following quantities as given in the literature of a particular event: association/dissociation or on/off rate constant, first/second/third/. order rate constant, equilibrium rate constant, catalytic rate constant, equilibrium association/dissociation constant, inhibition constant and binding affinity constant. Each entry can be retrieved through protein or nucleic acid or ligand name, SWISS-PROT AC number, ligand CAS number and full-text search of a binding or reaction event. KDBI currently contains 8273 entries of biomolecular binding or reaction events involving 1380 proteins, 143 nucleic acids and 1395 small molecules. Hyperlinks are provided for accessing references in Medline and available 3D structures in PDB and NDB. This database can be accessed at http://xin.cz3.nus.edu.sg/group/kdbi/kdbi.asp.

Pulse Oximeter-Derived Pleth Variability Index is a Reliable Indicator of Cardiac Preload in Patients Undergoing Liver Transplantation.

BACKGROUND: Accurate estimation of cardiac preload during liver transplantation is essential. The right ventricular end-diastolic volume index (RVEDVI) is recognized as a good preload indicator in patients undergoing liver transplantation. Recently, dynamic variation parameters including pleth variability index (PVI) have been used as predictors of fluid responsiveness. However, the correlation between PVI and preload status has not been well studied. We evaluated the relationship between PVI and RVEDVI during liver transplantation. METHODS: Eighteen patients undergoing liver transplantation were enrolled in this study. Data of hemodynamic parameters including PVI derived by Masimo Rainbow SET Pulse CO-Oximeter, central venous pressure (CVP), pulmonary arterial occlusion pressure (PAOP), and RVEDI were obtained at 10 defined time points throughout liver transplantation. The correlation between RVEDVI and CVP, PAOP, and PVI was analyzed using Spearman rank test. We also investigated the ability of PVI to accurately differentiate RVEDVI <123 or >142 mL/m(2) using receiver operating characteristic (ROC) analysis. RESULTS: There was fair to good correlation between PVI and RVEDVI (correlation coefficient = -0.492, P < .001). The correlation coefficient between CVP, PAOP, and RVEDVI was 0.345 and 0.463, respectively. A 13.5% cutoff value of PVI estimated the RVEDVI <123 mL/m(2) (area under the curve [AUC] = 0.762). A 12.5% cutoff value of PVI estimated the RVEDVI >142 mL/m(2) (AUC = 0.745). CONCLUSIONS: PVI presented as a reliable estimate of preload status and may be a useful predictor of fluid responsiveness in patients undergoing liver transplantation.

Accuracy and Trending of Continuous Noninvasive Hemoglobin Monitoring in Patients Undergoing Liver Transplantation.

BACKGROUND: Shift in large fluid volumes and massive blood loss during liver transplantation frequently leads to rapid changes in hemoglobin (Hb) concentration; thus, to ensure adequate tissue oxygenation, accurate and rapid determination of Hb concentration is essential in transplant recipients. The Radical-7 Pulse CO-Oximeter provides a noninvasive and continuous way to monitor Hb concentration (SpHb) in real time and is an ideal candidate for use during liver transplantation. In this study, we assessed the relationship between SpHb and total Hb (tHb) obtained from arterial blood samples during surgery. METHODS: Forty patients undergoing liver transplantation were enrolled in this study. tHb and time-matched SpHb were measured at 5 different phases throughout surgery. Paired SpHb and tHb levels were assessed using linear regression, Bland-Altman analysis, and the Critchley polar plot method. RESULTS: A total of 161 paired measurements with sufficient signal quality were analyzed. The correlation between SpHb and tHb was 0.59 (P < .001). Bland-Altman analysis revealed that a bias between SpHb and tHb was 2.28 g/dL, and limits of agreement (LoA) were from -0.78 to 5.34 g/dL. Trending analysis showed that 87% of data were located within the acceptable trending area, indicating that the trending ability was not satisfied. CONCLUSIONS: The Radical-7 Pulse CO-Oximeter was not sufficient to monitor Hb levels and trends during liver transplantation surgery in our cohort. In particular, in critical patients and in those with low Hb levels, invasive Hb measurement should be used for assessment.

Cardiac Output Assessed by the Fourth-Generation Arterial Waveform Analysis System Is Unreliable in Liver Transplant Recipients.

BACKGROUND: Liver transplant recipients often have violent hemodynamic fluctuation during surgery that may be related to perioperative and postoperative morbidity. Because there are some considerations for the risk of the pulmonary arterial catheter (PAC), the conventional invasive device for cardiac output (CO) measurement, a reliable and minimally invasive alternative is required. We validated the reliability of CO measurements with the use of a minimally invasive FloTrac system with the latest fourth-generation algorithm in liver transplant recipients. METHODS: Forty liver transplant recipients without atrial fibrillation, valvular pathology, or intracardiac shunt were recruited in this prospective, observational study. CO values measured by use of PAC with continuous thermodilution method (COTh) and FloTrac devices (COFT) were collected simultaneously throughout the operation for reliability validation. RESULTS: Four hundred pairs of CO data points were collected in total. The linear regression analysis showed a high correlation coefficient (73%, P < .001). However, the percent error between COTh and COFT was 42.2%, which is worse than the established interchangeability criterion of 30%. The concordance rates were calculated at 89% and 59% by 4-quadrant plot and polar plot analysis, respectively. Neither met the preset validation criteria (>92% for the 4-quadrant plot and >90% for polar plot analyses). CONCLUSIONS: Our study demonstrates that the CO measurements in liver transplant recipients by the latest FloTrac system and the PAC do not meet the recognized interchangeability criterion. Although the result showed improvement in linear regression analysis, it failed to display a qualified trending ability.

An automatic diagnostic system for CT liver image classification.

Computed tomography (CT) images have been widely used for liver disease diagnosis. Designing and developing computer-assisted image processing techniques to help doctors improve their diagnosis has received considerable interests over the past years. In this paper, a CT liver image diagnostic classification system is presented which will automatically find, extract the CT liver boundary and further classify liver diseases. The system comprises a detect-before-extract (DBE) system which automatically finds the liver boundary and a neural network liver classifier which uses specially designed feature descriptors to distinguish normal liver, two types of liver tumors, hepatoma and hemageoma. The DBE system applies the concept of the normalized fractional Brownian motion model to find an initial liver boundary and then uses a deformable contour model to precisely delineate the liver boundary. The neural network is included to classify liver tumors into hepatoma and hemageoma. It is implemented by a modified probabilistic neural network (PNN) [MPNN] in conjunction with feature descriptors which are generated by fractal feature information and the gray-level co-occurrence matrix. The proposed system was evaluated by 30 liver cases and shown to be efficient and very effective.

Shape from texture: estimation of planar surface orientation through the ridge surfaces of continuous wavelet transform.

In this correspondence, a method is proposed for estimating the surface orientation of a planar texture under perspective projection based on the ridge of a two-dimensional (2-D) continuous wavelet transform (CWT). We show that an analytical solution of the surface orientation can be derived from the scales of the ridge surface. A comparative study with an existing method is given.

Characteristics of Hebbian-type associative memories having faulty interconnections.

The performance of Hebbian-type associative memories (HAMs) in the presence of faulty (open- and short-circuit) synaptic interconnections is examined and equations for predicting network reliability are developed. The results show that a network with open-circuit interconnection faults has a higher probability of direct convergence than a network with short-circuit interconnection faults when the fraction of failed interconnections is small and the short-circuit signal is large. The results are extended to the case where network attraction radius is considered. Under certain assumptions, it is found that the expected numbers of neurons with b, b-1, b-2,. . .,1 input error bits in their state update are equal. Because of the capability of error correction, an asynchronous HAM is also found to have a higher probability of direct convergence than a synchronous HAM. Using these results, network reliability and generalization capability can be estimated when both the interconnection faults and the number of error bits in the probe vectors are taken into account.

Reliability characteristics of quadratic Hebbian-type associative memories in optical and electronic network implementations.

The performance capability of quadratic Hebbian type associative memories (QHAM's) in the presence of interconnection faults is examined, and equations for predicting the probability of direct convergence P(dc) given a fraction of interconnection faults are developed. The interconnection faults considered are the equivalent of open circuit and short circuit synaptic interconnections in electronic implementations. Our results show that a network with open circuit interconnection faults has a higher probability of direct convergence P (dc) than a network with short circuit interconnection faults, when the fraction of failed interconnections p is small and the short circuit signal G is large. Certain values of G are found to have only mild effects on network performance degradation. Network reliability characteristics taking the generalization capability into account are also analyzed. All of these results are compared with those of Hebbian type associative memories (HAM's), which have linear association network models. Our results indicate that QHAM's have much higher network capacity and fault tolerance capability in the presence of interconnection faults. However, the fault tolerance to input errors in QHAM's is much less than that of HAM's.

Endometrium estimation in a sequence of ultrasonic images.

In this paper a novel algorithm for motion estimation of the endometrium in a sequence of ultrasonic images is presented. The algorithm used is based on the criterion that a pixel of a motion object at different times has a different gray value. The motion estimation includes motion frequency and thickness; the former one is determined by the detection of change of a pixel value in a sequence of images during a given time period, and the latter is the result of the object's dimension divided by its extended width. The algorithm has been tested on synthetic and real images, and the results are encouraging.

A hierarchical model for PACS.

In this paper, a hierarchical model for Picture Archiving and Communication Systems (HPACS) is presented and implemented at Taichung Veterans General Hospital (TCVGH) in Taiwan. Despite the fact that the HPACS is built on the architecture of the second generation PACS, it offers many improved features and has advantages over the second generation PACS, such as the user security control, fast resource dispatch and efficient resource management. This HPACS can be used as a reference model for a hospital with any scale-size. The real implementation of HPACS is currently undertaken in the Taichung Veterans General Hospital (TCVGH), Taiwan, Republic of China and consists of four phases with the first two phases already completed. It is the first pilot system ever to be implemented successfully in a large-scale hospital in Taiwan. The experiences have illustrated the great promise of the HPACS in the future.