微型计算机在肾图中的应用

用单板计算机配合肾图仪,可自动采集肾图数据、计算并打印指标及曲线.75例病人的配对比较结果表明:计算机结果与原肾图仪无显著性差异.由此证明我们编制的应用程是合理可行的.     

粘病毒抵抗基因-1启动子88位点G/T多态性影响乙型肝炎病毒感染的自然转归

目的探讨乙型肝炎病毒（HBV）自限感染和慢性感染与粘病毒抵抗基因-1（MxA）启动子的-88位点G／T单核苷酸多态性的关系。方法收集100例抗-HBs和抗-HBc阳性的HBV自限感染者和340例慢性感染者的外周全血，提出基因组DNA；采用竞争分化聚合酶链反应技术为基础的方法进行MxA-88G／T基因分型；采用单因素Odds ratio和x^2检验等方法进行统计学分析。结果MxA-88G／G基因型（低表达型）检出率为50．2％（221／440），T／T基因型（高表达型）检出率为5．5％（24／440），G／T杂合型检出率为44．3％（195／440）。与慢性感染患者相比，自限感染患者携带较低的G／G基因型（41．0％与52．9%，P〈0．05）、G等位基因（62．5％与75．3％，P〈0．01）和较高的T／T基因型（16．0％与2．4%，P〈0．01）、T等位基因（37．5％与24．7％，P〈0．01），而两者之间的G／T杂合型差异无统计学意义。结论MxA-88G／T基因型能在一定程度上影响HBV感染的自然转归，有望成为临床上HBV感染转归的预测指标。     

SNP及其在畜牧业中的应用前景

SNP(single nucleotide polymorphisns-单核苷酸多态性)是继限制性片段长度多态性和微卫星之后，新发展起来的第3代分子标记。已成为一类新的遗传标记，广泛应用于基因定位、克隆和遗传多样性研究。本文介绍了SNP的特性、检测方法及其在畜牧业研究生产中的广泛利用前景。并提出了SNP研究中遇到的一些问题。     

Impact response of periodontal tissues

A new impact response method using a fracture of a pencil-lead to produce an excitation pulse is proposed. Impact excitations (rectangular pulse, triangular pulse and half-sine pulse) are strictly given in physical and mathematical definitions and complete solutions to the impact excitations are provided for Noyes' model of the human tooth. When a relatively long triangular pulse is applied to Noyes' model, which can express the physical characteristic of periodontal tissues, a sinusoidal damped vibration of a single degree-of-freedom model is approximately obtained. The acceleration response is characterised by the physical parameters (T, δ and A_o) and mechanical elements (m₁, c₁ and k) of which a single degree-of-freedom model is composed. By means of this method, the values of the parameters and elements in the cases of healthy maxillary, healthy mandibular and pathological mandibular incisors are obtained. The single degree-of-freedom model can express the high-frequency spectra of Noyes' model. The pathological tooth is characterised by a longer damped time constant and a larger acceleration maximum. This impact response method can effectively be applied to clinical diagnosis in view of the physical parameters and mechanical elements which have been derived.     

MRI and SPECT findings in amyotrophic lateral sclerosis

Summary MRI was performed in 21 patients and single photon emission computed tomography (SPECT) withN-isopropyl-p-¹²³I iodoamphetamine in 16 patients, to visualize upper motor neurone lesions in amyotrophic lateral sclerosis. T2-weighted MRI revealed high signal along the course of the pyramidal tract in the internal capsule and cerebral peduncle in 4 of 21 patients. SPECT images were normal in 4 patients, but uptake was reduced in the cerebral cortex that includes the motor area in 11.     

A Bayesian iterative transmission gradient reconstruction algorithm for cardiac SPECT attenuation correction

Background  High-quality attenuation maps are critical for attenuation correction of myocardial perfusion single photon emission computed tomography studies. The filtered backprojection (FBP) approach can introduce errors, especially with low-count transmission data. We present a new method for attenuation map reconstruction and examine its performance in phantom and patient data. Methods and Results  The Bayesian iterative transmission gradient algorithm incorporates a spatially varying gamma prior function that preferentially weights estimated attenuation coefficients toward the soft-tissue value while allowing data-driven solutions for lung and bone regions. The performance with attenuation-corrected technetium 99m sestamibi clinical images was evaluated in phantom studies and in 50 low-likelihood patients grouped by body mass index (BMI). The algorithm converged in 15 iterations in the phantom studies. For the clinical studies, soft-tissue estimates had significantly greater uniformity of mediastinal coefficients (mean SD, 0.005 cm⁻¹ vs 0.011 cm⁻¹; P<.0001). The accuracy and uniformity of the Bayesian iterative transmission gradient algorithm were independent of BMI, whereas both declined at higher BMI values with FBP. Attenuation-corrected perfusion images showed improvement in myocardial wall variability (4.8% to 4.1%, P=.02) for all BMI groups with the new method compared with FBP. Conclusion  This new method for attenuation map reconstruction provides rapidly converging and accurate attenuation maps over a wide spectrum of patient BMI values and significantly improves attenuation-corrected perfusion images.     

单细胞凝胶电泳技术在生殖细胞DNA损伤检测中的应用

单细胞凝胶电泳技术(SCGE)是一种快速检测单个细胞DNA损伤的实验技术,在生殖细胞DNA损伤的检测中广泛应用。本综述系统介绍了SCGE在睾丸生精细胞、支持细胞、间质细胞、卵巢细胞以及卵母细胞等生殖细胞DNA损伤检测中的应用现状,并对SCGE在生殖毒性检测中的发展提出了展望。     

Differential effects of the pyrethroid tetramethrin on tetrodotoxin-sensitive and tetrodotoxin-resistant single sodium channels

The differential effects of the pyrethroid tetramethrin on tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) single sodium channel currents in rat dorsal root ganglion (DRG) neurons were investigated using the outside-out configuration of patch-clamp technique. Channel conductances were 10.7 and 6.3 pS for TTX-S and TTX-R sodium channels, respectively, at a room temperature of 24–26°C. The single-channel current of TTX-S sodium channels at the test potential of −30 mV was −1.27 ± 0.25 pA, and was not changed after exposure to 10 μM tetramethrin (−1.28 ± 0.23 pA). The open time histogram of TTX-S single-channel currents could be fitted by a single exponential function with a time constant of 1.27 ms. After exposure to 10 μM tetramethrin, the open time histogram could be fitted by the sum of two exponential functions with time constants of 1.36 ms (τ_fast) and 5.73 ms (τ_low). The percentage of contribution of each component to the population was 62% for the fast component representing the normal channels and 38% for the slow component representing the tetramethrin modified channels. The amplitudc of TTX-R single-channel currents was slightly changed from −0.72 ± 0.14 to −0.83 ± 0.07 pA by 10 μM tetramethrin. The open time histogram of TTX-R single-channel currents could be fitted by a single exponential function with a time constant of 1.92 ms. In the presence of 10 μM tetramethrin, the open time histogram could be fitted by the sum of two exponential functions with time constants of 2.07 ms (τ_fast) and 9.75 ms (τ_slow). The percentage of contribution of each component was 15% for the fast, unmodified component and 85% for the slow, modified component. Differential effects of tetramethrin on the open time distribution of single sodium channel currents explains the differential sensitivity of TTX-S and TTX-R sodium channels.