Two-dimensional measurement of blood flow velocity in rat arteries based on ultrasonic particle image velocimetry / 南方医科大学学报

<p><b>OBJECTIVE</b>Ultrasonic pulse wave Doppler technique for noninvasive blood flow imaging does not provide precise information of complex blood flow field, and observing two-dimensional artery blood flow field distribution provides important clinical information for cardiovascular disease.</p><p><b>METHODS</b>Ultrasonic particle image velocimetry (Echo PIV) was used to measure blood flows on B-mode ultrasonic particle image to assess the whole field velocity of the blood vessels in 5 groups of healthy rats. The reliability of Echo PIV was verified in comparison with ultrasonic Doppler method in 3 cardiac cycles.</p><p><b>RESULTS AND CONCLUSION</b>The results of Echo PIV were similar with the those of ultrasound spectral Doppler. The Echo PIV-measured peak and average velocity within 3 cardiac cycles were about 5%-10% and 2%-8% below the values measured by the ultrasonic spectral Doppler, respectively, but these differences were not statistically significant (P>0.05). As a new technique for monitoring complex blood flow in stenotic arteries, echo PIV can be used to directly and non-invasively assess whole field hemodynamic changes in blood vessels in real time and distinguish different groups of rats by velocity.</p>

Gluconate 5-dehydrogenase (Ga5DH) participates in Streptococcus suis cell division

Bacterial cell division is strictly regulated in the formation of equal daughter cells. This process is governed by a series of spatial and temporal regulators, and several new factors of interest to the field have recently been identified. Here, we report the requirement of gluconate 5-dehydrogenase (Ga5DH) in cell division of the zoonotic pathogen Streptococcus suis. Ga5DH catalyzes the reversible reduction of 5-ketogluconate to D-gluconate and was localized to the site of cell division. The deletion of Ga5DH in S. suis resulted in a plump morphology with aberrant septa joining the progeny. A significant increase was also observed in cell length. These defects were determined to be the consequence of Ga5DH deprivation in S. suis causing FtsZ delocalization. In addition, the interaction of FtsZ with Ga5DH in vitro was confirmed by protein interaction assays. These results indicate that Ga5DH may function to prevent the formation of ectopic Z rings during S. suis cell division.

Measurement method of arterial shear stress of rats model based on ultrasonic particle imaging velocimetry / 生物医学工程学杂志

The development and progression of atherosclerosis and thrombosis are closely related to changes of hemodynamics parameters. Ultrasonic pulse wave Doppler technique is normally used for noninvasively blood flow imaging. However, this technique only provides one-dimensional velocity and depends on the angle between the ultrasound beam and the local velocity vector. In this study, ultrasonic particle image velocimetry method was used to assess whole field hemodynamic changes in normal blood vessels. By using the polynomial fitting method, we investigated the velocity gradient and assessed the shear in different blood flow velocity of 10 healthy rats. It was found that using four polynomial fitting could result in optimal measurement results. The results obtained by ultrasonic particle image velocimetry accorded with the results obtained using Doppler technique. The statistical average of cyclical vessel wall shear stress was positively related to the locational mean velocity. It is proven that ultrasonic particle image velocimetry method could be used to assess directly the real-time whole field hemodynamic changes in blood vessels and was non-invasively, and should be a good prosperous technique for monitoring complex blood flow in stenotic ar- teries.

The receptors and entry of measles virus: a review / 生物工程学报

Measles virus is an enveloped virus with a non-segmented negative-sense RNA genome. Two envelope glycoproteins on the viral surface, namely hemagglutinin (H) and membrane fusion protein (F), are responsible for the virus entry into susceptible host cells. The specific interaction between H and its cellular receptors is a key step in successful virus infection, determining the infectivity and tissue tropism of the measles virus. Thus far, three H receptors have been identified, including the complement regulatory molecule CD46, the signaling lymphocyte activation molecule (SLAM) and the cell adhesion molecule Nectin-4. Here, we reviewed our molecular understanding on the recognition mechanism of these receptors by the viral H protein, aiming to promote future studies on antiviral drug design and measles virus-based oncolytic therapy.

An octamer of enolase from Streptococcus suis

Enolase is a conserved cytoplasmic metalloenzyme existing universally in both eukaryotic and prokaryotic cells. The enzyme can also locate on the cell surface and bind to plasminogen, via which contributing to the mucosal surface localization of the bacterial pathogens and assisting the invasion into the host cells. The functions of the eukaryotic enzymes on the cell surface expression (including T cells, B cells, neutrophils, monocytoes, neuronal cells and epithelial cells) are not known. Streptococcus suis serotype 2 (S. suis 2, SS2) is an important zoonotic pathogen which has recently caused two large-scale outbreaks in southern China with severe streptococcal toxic shock syndrome (STSS) never seen before in human sufferers. We recently identified the SS2 enolase as an important protective antigen which could protect mice from fatal S.suis 2 infection. In this study, a 2.4-angstrom structure of the SS2 enolase is solved, revealing an octameric arrangement in the crystal. We further demonstrated that the enzyme exists exclusively as an octamer in solution via a sedimentation assay. These results indicate that the octamer is the biological unit of SS2 enolase at least in vitro and most likely in vivo as well. This is, to our knowledge, the first comprehensive characterization of the SS2 enolase octamer both structurally and biophysically, and the second octamer enolase structure in addition to that of Streptococcus pneumoniae. We also investigated the plasminogen binding property of the SS2 enzyme.

X-ray diffraction analysis of glycoprotein D from herpes simplex virus type 2 / 生物工程学报

Glycoprotein D (gD) of Herpes simplex virus type 2 (HSV-2) is a key factor mediating the entry of HSV-2 into host cells. In order to explain the mechanism underlying the gD-mediated receptor-binding and viral entry, we performed a structural study on HSV-2 gD. The ectodomain of the gD protein encompassing residues 1 to 285 was expressed by baculovirus-infected insect cells as a secreted soluble protein with a C-terminal hexa-his tag. The protein was then purified by affinity and size-exclusion chromatography. The purified protein was successfully crystallized using the hanging-drop vapor-diffusion at 18 degrees C in a condition consisting of 0.1 mol/L Hepes pH 7.2, 5% (V/V) 2-methyl-2,4-pentanediol (MPD) and 10% PEG 10 000. The crystals diffracted to 1.8 angstroms resolution and belonged to space group P21, with unit-cell parameters alpha = 63.6, b = 55.4, c = 65.3 angstroms, beta = 96.3 degrees.

hNUDT16: a universal decapping enzyme for small nucleolar RNA and cytoplasmic mRNA

Human NUDT16 (hNUDT16) is a decapping enzyme initially identified as the human homolog to the Xenopus laevis X29. As a metalloenzyme, hNUDT16 relies on divalent cations for its cap-hydrolysis activity to remove m⁷GDP and m²²⁷GDP from RNAs. Metal also determines substrate specificity of the enzyme. So far, only U8 small nucleolar RNA (snoRNA) has been identified as the substrate of hNUDT16 in the presence of Mg²(+). Here we demonstrate that besides U8, hNUDT16 can also actively cleave the m⁷GDP cap from mRNAs in the presence of Mg²(+) or Mn²(+). We further show that hNUDT16 does not preferentially recognize U8 or mRNA substrates by our cross-inhibition and quantitative decapping assays. In addition, our mutagenesis analysis identifies several key residues involved in hydrolysis and confirms the key role of the REXXEE motif in catalysis. Finally an investigation into the subcellular localization of hNUDT16 revealed its abundance in both cytoplasm and nucleus. These findings extend the substrate spectrum of hNUDT16 beyond snoRNAs to also include mRNA, demonstrating the pleiotropic decapping activity of hNUDT16.

An unexpected similarity between antibiotic-resistant NDM-1 and beta-lactamase II from Erythrobacter litoralis

NDM-1 (New Delhi metallo-beta-lactamase) gene encodes a metallo-beta-lactamase (MBL) with high carbapenemase activity, which makes the host bacterial strain easily dispatch the last-resort antibiotics known as carbapenems and cause global concern. Here we present the bioinformatics data showing an unexpected similarity between NDM-1 and beta-lactamase II from Erythrobacter litoralis, a marine microbial isolate. We have further expressed these two mature proteins in E. coli cells, both of which present as a monomer with a molecular mass of 25 kDa. Antimicrobial susceptibility assay reveals that they share similar substrate specificities and are sensitive to aztreonam and tigecycline. The conformational change accompanied with the zinc binding visualized by nuclear magnetic resonance, Zn(2+)-bound NDM-1, adopts at least some stable tertiary structure in contrast to the metal-free protein. Our work implies a close evolutionary relationship between antibiotic resistance genes in environmental reservoir and in the clinic, challenging the antimicrobial resistance monitoring.

Quality assurance of digital mammography X-ray system / 中南大学学报(医学版)

OBJECTIVE@#To improve the performance quality of mammography X-ray system, and to decrease misdiagnoses.@*METHODS@#Quality assurance was tested and controlled from such aspect as measurement of half value layer, beam quality assessment, breast entrance exposure average glandular dose, tube tunsion accuracy and reproducibility, and radiation output.@*RESULTS@#The image contrast, mistiness and noise were optimized.@*CONCLUSION@#With the quality assurance of the digital mammography X-ray system, the variations of the performance parameters remain in the range of permission, thus improving the quality of mammography.

Development of Temperature Control System for Hyperthermia Based on PWM / 医疗卫生装备

Objective To develop a hyperthermia temperature control system for the treatment of pelvic inflammatory disease. Methods Temperature was controlled by using PWM method based on a single chip computer. The system was heated by using heating wire. In the whole cycle of T, the heating wire's work time was divided into three different stages according to different temperature of system: in the lower temperature, the duty cycle of the heating wire's work time was 100%; when the system temperature entered to a certain stage, a control variable was obtained through the PID algorithm which was used to compare the difference between the current temperature and the temperature requirements. The control variable determined the duty cycle of the heating wire's work time: the more close to the temperature required for the temperature of system, the duty cycle of the heating wire's work time was more close to 0; if the temperature exceeded a predetermined value, then the heating wire would not heat in the whole cycle. Results The accuracy of the temperature control system was ?0.2 ℃, the overshoot of the temperature control system was ?0.3 ℃, and the response time of the temperature control system was 500 seconds. Conclusion The temperature control method has high precision, small overshoot, and the right response time, which can meet the requirements of constant temperature of hyperthermia treatment. Besides, it is simple and cheap.

Key technique of embedded medical video transmission system / 医疗卫生装备

Objective To realize three key techniques in medical video transmission system including the establishment of cross-compilation environment,OSD superposition by drive equipment,the resolve of network delay of MPEG4 video stream.Methods Embedded Linux was used to programming.Results The three key techniques were realized.Conclusion The resolve of key techniques sweeps off the obstacles in the construction of medical video transmission system.

Analysis of sleeping physiological signals based on fuzzy prediction theory / 医疗卫生装备

In this article,a new approach tosleep analysis based on fuzzy prediction theory is described.This article gives a general introduction todetection and processing of biological signals with LabVIEW technique.The designed fuzzy measurement system is applied tofuzzy prediction analysis of physiological signals.The experiment results show that our method of analysis is correct.SoLabVIEW-based fuzzy prediction analysis is more helpful for early diagnosis,monitoring and prognosis assessment of some diseases.The method might reflect the sleep state of SASpatient.

Function Analysis of the Largest Lyapunov Exponent of Masseter Muscle / 医疗卫生装备

Objective To apply chaos characteristics to prediction of the unilateral mastication.Methods The paper calculated the Largest Lyapunov Exponent of the masseter muscle of some males and females with a method from small data sets,which then was processed by reusable two-factor analysis of variance.Results The results shows that the signal of the masseter muscle has chaos characteristics,the male's Largest Lyapunov Exponent is higher that the female's,and the chaos degree of the masseter muscle on both sides is consistent nearly.Conclusion The Largest Lyapunov Exponent can be used to characterize the signal of the masseter muscle.Comparative Analysis of the Largest Lyapunov Exponent on both sides can be used as reference when to predict and diagnose the unilateral mastication.

Analysis of epileptic electroencephalogram based on multi-variable state space reconstruction / 医疗卫生装备

Based on the high-dimension chaos characteristics of electroencephalogram(EEG) and the analysis by the multi-variable state space reconstruction,better estimation of the correlative dimension can be obtained by dividing the brain into two parts and using eight EEG channels as the reconstruction samples.Lorenz system was firstly tested by request of the amount of data to test the feasibility of the algorithms.After Comparing the high-dimension data of the EEG of epileptic patients with the results of control subjects,it is indicated that the multi-variable state space reconstruction is applicable in short time noise-containing time sequences to obtain reliable results and can free the researchers from the hard choice of delay time and embedding dimension.

The Experiment Research on the Influence of Some MR Parameters on Signal-to-Noise Ratio / 实用放射学杂志

Objective To research some parameters' influence on signal-to-noise ratio (SNR) of MR. Methods Magphan phantom was used to do experiments on 1.5T, 0.5T and 0.23T MRI. Scan parameters such as NEX, scan matrix and slice thickness were altered.Evaluate whether the change of SNR varied with parameter to be in accordance with the SNR law.Results (1) When spin echo pulse applied and NEX changed, the results of high field device A and B weren't in accordance with SNR theory, and high filed device C and low field device F were in accordance with SNR theory. When fast spin echo pulse applied and NEX changed, the result of device B was in accordance with SNR theory. (2) When scan matrix changed, measured value was lower than ideal value for little matrix, and vice versa. (3) The measured value was very closely to ideal value for little slice thickness. When slice thickness exceed 5 mm, the difference between the measured value and ideal value was significance.Conclusion Based on the SNR theory, the user of MRI should consider the running characteristic of MR system to select scan parameters.

Development of programming cardiac trigger apparatus and its application to myocardial contrast echocardiography / 医疗卫生装备

This paper introduces a programming cardiac trigger apparatus used for the study of quantitative measurement of myocardial blood flow with myocardial contrast echocardiography.The design of hardware circuit based on MCU and the scheme of software based on Keil C51 are mainly discussed.With stable and reliable working,this apparatus provides a kind of technical support for the study of quantitative measurement of myocardial blood flow with continuous intravenous injection of sonicated microbubbles.

Application of wireless transfer technology to medical instrument development / 医疗卫生装备

In many medical instrumentation systems, there exists a long distance between manipulation platform and host unit. Wireless data transferring between the platform and the host could be a feasible way to set parameters. This paper introduces wireless transmitter and receiver circuit based on encoder chip PT2262 and decoder chip PT22720, and presents some typical applications in medical instrument development.