关于人体信号和医学超声信号

一、引言 疾病的危险程度可以分为高、中、低三等.目前临床检查手段又可分为侵入及损伤、微侵入及微损伤、非侵入及无损伤,显然非侵入及无损伤的检查手段受到各种患者和健康检查者的欢迎.见表1.     

激光多普勒微血流测定以及临床应用

<正> 用激光多普勒血流仪(下称LDF)测微区血流的优点:可反映被测微区组织自然状态的供血情况,微血管内血细胞压积不过分增高时,其输出信号和血细胞流量线性关系好。非侵入、无损伤、无痛苦,可实时或连续测量,设备及操作简便。其缺点:测得结果仅是一个相对的流量或相对的容积速度;血细胞压积过高时输出     

MRI中T2WI高信号长度与急性颈脊髓损伤程度相关性研究

目的：探讨MRI中T2WI高信号长度与急性颈脊髓损伤程度的关系。方法：急性颈脊髓损伤患者37例,其中脊髓完全损伤19例,不完全损伤18例。全部病人均于伤后1～7天行MRI检查,于T2加权矢状位成像上选取高信号最长层面量取其长度,并分析其与颈脊髓损伤程度的关系。结果：急性颈脊髓损伤患者颈髓矢状面T2WI高信号长度,脊髓完全性损伤组明显高于不完全性损伤组（P〈0．01）。结论：MRI是临床诊断急性脊髓损害程度及评估其预后的良好的无创性检测方法。     

用线性预测分析膝部的振动信号

目前用于膝部软骨疾病的诊断方法是侵入式的,并且导致许多危险。于是需要发展一种安全的、客观的、非侵入的方法用于早期诊断、定位和改善膝部软骨的疾病。此法是建立在对正常运动情况下关节头处两关节面之间的摩擦造成的振动的分析的基础上的,本文研究了发展此法的可能性。用线性预测建立的模型可以对膝部振动信号     

呼吸信号检测技术研究现状

呼吸检测方法主要分为接触式和非接触式2大类.接触式检测方法包括容积式呼吸检测法、速度式呼吸检测法、温度检测法、位移检测法、阻抗检测法、可穿戴技术和睡眠床垫等.这些方法属于无创检测且技术成熟,但都需要电极或传感器直接或间接接触人体,使人体受到一定的约束或限制,不适合用于严重烧伤患者和新生儿的呼吸监测.非接触式检测利用电磁波、光等媒介,使用无需与人体接触的电极或传感器,可在人体自然状态下对呼吸信号进行非接触检测,特别是基于红外线和生物雷达的非接触检测方法,已成为国内外研究的热点,可用于临床、社区医疗及家庭监护.     

磁敏感加权成像对脑血管疾病的诊断价值研究

目的:分析3.0T磁共振(MRI)磁敏感加权成像(SWI)检查在脑血管疾病诊断中的应用价值.方法:选取2021年6月至2021年12月本院收治的82例脑血管疾病患者的临床资料,患者均经数字减影血管造影确诊为脑血管疾病.其中脑梗死25例,脑血管畸形35例,脑肿瘤14例,神经变性性疾病8例.所有患者均进行MRI常规及SWI检查.分析对比SWI对脑血管疾病诊断的准确性;SWI对脑血管疾病患者病灶的检出率;对比不同脑血管疾病MRI常规及SWI表现.结果:SWI对脑血管疾病断准确性为85.36％,MRI常规检查为50.00％,SWI明显高于MRI常规检查(P<0.05);82例患者经脑血管造影确诊存在病灶97个,SWI检查检出90个(93.81％)明显高于MRI常规检查(80.41％)(P<0.05).①脑梗死/脑出血MRI检查可见:脑梗死患者在T1WI上显示低信号、T2WI高信号;SWI检查显示主体为低信号,部分患者见有混杂高信号.②脑血管畸形MRI检查可见SWI可见病灶部位存在有高密度的散在条状、点状低信号.③脑肿瘤MRI检查可见在SWI图像中病灶部位为低信号,14例患者中病灶边界清晰11例,不清晰3例.④神经变性性疾病SWI检查显示患者病变显示为苍白球及黑质部位呈现多发异常低信号的铁沉淀.结论:3.0T磁共振SWI检查可了解脑部血管分布、结构、铁沉积等情况,对脑血管疾病诊断效能好,在临床早期筛查诊断中具有一定的应用前景.     

低场强MRI可首选诊断膝关节隐匿性骨折

背景：MRI检查可以早期确诊隐匿性骨折,低场强磁共振成像还具有专有线圈使图像更清晰的优点。 目的：分析低场强MRI在膝关节隐匿性骨折诊断中的应用价值。 方法：回顾性分析45例经手术、关节镜检查或临床证实的膝关节隐匿性骨折患者低场强MRI情况。 结果与结论：45例病例在X射线平片正侧位上均未见异常,而低场强MRI检查均呈现T1WI呈低信号,T2WI呈高信号,在STIR上病灶与正常骨组织的对比度更高,显示出不同部位隐匿性骨折的病变部位、范围及形态,其中34例伴交叉韧带、副韧带及半月板撕裂。提示低场强MRI能敏感显示创伤性膝关节隐匿性骨折的病变特点及严重程度,诊断准确,同时能发现膝关节韧带、肌腱及软骨的损伤,为首选检查手段。     

磁共振成像评价膝关节半月板损伤

背景：传统的影像学检查方法在膝关节半月板损伤诊断方面有很大的局限性,难以检测膝关节半月板的全部情况。 目的：以磁共振成像评价膝关节半月板损伤。 方法：回顾性分析以往经临床治疗证实的膝关节半月板损伤患者,分析其磁共振成像征象的特征并分级,显示半月板受损情况,与关节镜或手术结果进行对照研究。 结果与结论：膝关节半月板损伤的磁共振成像中,Ⅰ级表现为不与半月板关节面接触的点状或圆形高信号,Ⅱ级表现为半月板内出现水平或斜行的线样或条状高信号影,但未达到半月板关节面缘,Ⅲ级表现为半月板内线条样或复杂形态高信号影延伸至半月板的关节面,可伴有半月板形态的改变。磁共振成像作为一种无创性的检查手段,能清楚地显示半月板变性和撕裂,正确地诊断半月板损伤的部位、形态及严重程度,这对临床确定治疗方案有非常重要的指导价值。     

低场MRI对膝关节半月板损伤诊断的临床价值

目的 探讨低场MRI在膝关节半月板损伤中的诊断价值.材料和方法 搜集我院2007年2月-6月间,进行MRI检查的141例151个膝关节,进行半月板损伤诊断的回顾性分析.检查序列包括冠状面FSET2WI、矢状面SET1WI、FSET2WI及STIRE.结果低场MRI显示正常半月板内可以见似三角型或片状高信号,不延伸至关节面或游离缘,临床症状不明显;损伤半月板除信号改变外,其形态可全部或局部不规则,常同时伴关节组成骨及关节软骨、滑膜囊、软组织等的异常信号,临床症状明显.本组资料中,MRI诊断半月板损伤130个,14个膝关节外院行关节镜检查,12个证实有半月板撕裂.低场MRI对半月板撕裂的诊断率85.7%.结论 低场MRI能较好的显示膝关节半月板损伤,能对其进行损伤分级,显示损伤的特点和严重程度,为临床选择合适的治疗方案提供依据.     

信号响应性基因载体及其应用研究

获得合适的基因载体是基因治疗取得成功的关键因素之一。由于病毒载体存在安全隐患问题,人们致力于非病毒载体的研究,但其递送效果仍不理想。为了提高其基因递送效率,改善其靶向性及特异性,并调控其在体内及细胞内的动态,研发具有响应机体内外各种物理、化学及生物信号功能的非病毒载体,逐渐形成了一个重要的研究方向,受到学术界与产业界的极大关注。本文从信号的性质及来源上,将非病毒基因载体分为响应外部物理信号和响应内部化学与生物信号;从响应模式上,将其分为响应单一信号和响应多种信号。系统阐述了此类载体的结构特点、作用机理,并对其研究进展和实际应用进行了综合评述。     

A point mutation in CD28 distinguishes proliferative signals from survival signals

Upon interaction with its ligand, B7, CD28 becomes phosphorylated on tyrosines. One tyrosine in particular (Y170 in mouse CD28, Y173 in human CD28) has received much attention. This is because it permits CD28 to recruit SH2-containing signaling molecules, including phosphoinositide 3 kinase, Grb2 and Gads. Using mice we employed a transgenic approach to express a tyrosine-->phenylalanine mutant form of CD28 that uncouples these SH2-mediated interactions from CD28. The CD28 mutant is unable to up-regulate expression of the prosurvival protein Bcl-xL, rendering the T cells more susceptible to radiation-induced death. Nonetheless, this mutated form of CD28 still prevents the induction of anergy and promotes T cell proliferation, interleukin 2 secretion and B cell help. Thus, we describe a single point mutation within the CD28 cytoplasmic domain that uncouples signals required for proliferation and survival.     

Clonal induction of helper T cells: conversion of specific signals into nonspecific signals

The mechanism by which murine helper T cells specific for sheep erythrocytes (SRC) or horse erythrocytes (HRC) exert their effect in an antibody response has been studied in a specific in vitro helper assay in which T cells specific for SRC (TSRC) do not support an antibody response against HRC and in which T cells specific for HRC (T'HRC) do not support an antibody response against SRC. Either population of helper T cells can support an antibody response to both antigens if the homologous and an unrelated antigen are present at the same time. The helper effect is mediated by stable soluble products, the induction of which is antigen specific and independent of B cells. To exclude T cell-T cell interactions, pure populations of specific helper T cells were obtained by long-term culture in vitro of in vivo primed T cells followed by single cell cloning. Clones of T'SRC or T'HRC are highly specific both in vitro and in vivo. For in vivo experiments syngeneic nude mice, selectively and specifically reconstituted with cloned helper T cells, were used. While specific helper T cells can also provide help in vitro for an unrelated antigen, in vivo only specific T cell help is revealed.     

Electrically evoked myoelectric signals.

Electrical stimulation of the nervous system is attracting increasing attention because of the possibilities it offers for physiological investigations, clinical diagnosis, muscle function assessment, noninvasive muscle characterization, and functional control of paralyzed extremities. Parameters of the myoelectric signal evoked by surface stimulation of a muscle motor point or by stimulation of a nerve trunk by means of implanted electrodes provide information about muscle performance and properties if the stimulation artifact is properly removed or suppressed. Comparison of these parameters with those obtained during voluntary contractions provides additional insight into muscle physiology. The relationships between myoelectric signal amplitude parameters, spectral parameters, and conduction velocity are discussed with special reference to muscle fatigue. This review focuses on a few methodological aspects concerning electrical stimulation of the peripheral nervous system, detection, and processing of the electrically evoked myoelectric signals in skeletal muscles. The state of the art of the following issues is discussed: (1) properties of voluntary and electrically evoked myoelectric signals; (2) techniques for evoking and detecting myoelectric signals; (3) techniques for suppression of stimulation artifacts; (4) effect of stimulation waveforms and electrode properties; (5) signal processing techniques for electrically evoked myoelectric signals; (6) physiological significance of myoelectric signal variables; (7) order of recruitment of motor units during electrical stimulation; (8) myoelectric manifestations of fatigue in electrically stimulated muscles; (9) assessment of crosstalk by electrical stimulation; and (10) applications in sport, rehabilitation, and geriatric medicine.     

微波激励热声信号采集系统

为了能够成功采集和提取微波脉冲照射生物组织所产生的微弱热声信号,实现对组织的微波热声成像,开发出了一种热声信号数据采集系统.制作了增益105dB、带宽3MHz的可调增益信号预处理器,结合软件设计解决了四通道大数据量保存问题;通过对LabVIEW和C语言进行混合编程实现数字式平均计算,对强噪声背景中的信号进行消噪处理,解决了平均计算过程中的数据漂移问题,这种方法还能够去除奇异信号从而获得更为准确的结果;最后通过实验对微波激励的信号进行采集和分析.实验结果证明本采集系统完全可以满足微波热声成像中热声信号采集的要求.达到预期效果.     

Cell signals transduced by complement

The complement system is composed of soluble blood plasma proteins and cell membrane proteins. A major function of the soluble complement proteins is to bind to and destroy invading pathogens. The membrane proteins of the complement system are divided into complement receptors and complement regulatory proteins. Complement receptors on phagocytic cells promote binding and engulfment of pathogens coated with complement opsonins, whereas complement regulatory proteins protect healthy tissues from accidental damage by the soluble complement proteins. Upon binding of complement proteins or protein fragments that are generated during complement activation, these receptors and regulatory proteins transduce various signals into cells bearing them. The complement membrane attack complex C5b-9 binds to cell membranes, independent of any receptor, and also activates multiple signaling pathways. The receptor-dependent and -independent signals transduced by complement components are of great consequence to health and disease. Complement plays an important role in immunoregulation by activating B and T lymphocytes. It may also exert pro- or anti-apoptotic effects on various cell types. At sublytic doses, the complement membrane attack complex has wide-range effects on many cell types leading to cellular responses, such as secretion, adherence, aggregation, chemotaxis and even cell division. Sublytic complement also induces increased cell resistance to lytic doses of complement. Finally, certain pathogens take advantage of complement membrane proteins to gain entry into cells. The emerging data on these complement-related signaling pathways is hereby described.