Noninvasive loading of the rat ulna in vivo induces a strain-related modeling response uncomplicated by trauma or periostal pressure

Adaptive changes in bone modeling in response to noninvasive, cyclic axial loading of the rat ulna were compared with those using 4-point bending of the tibia. Twenty cycles daily of 4-point bending for 10 days were applied to rat tibiae through loading points 23 and 11 mm apart. Control bones received nonbending loads through loading points 11 mm apart. As woven bone was produced in both situations, any strain-related response was confounded by the response to direct periosteal pressure. Four-point bending is not, therefore, an ideal mode of loading for the investigation of strain-related adaptive modeling. The ulna's adaptive response to daily axial loading over 9 days was investigated in 30 rats. Groups 1–3 were loaded for 1200 cycles: Group 1 at 10 Hz and 20 N, Group 2 at 10 Hz and 15 N, and Group 3 at 20 Hz and 15 N. Groups 4 and 5 received 12,000 cycles of 20 N and 15 N at 10 Hz. Groups 1 and 4 showed a similar amount of new bone formation. Group 4 showed the same pattern of response but in reduced amount. The responses in Groups 2 and 3 were either small or absent. Strains were measured with single-element, miniature strain gauges bonded around the circumference of dissected bones. The 20 N loading induced peak strains of 3500–4500 strain. The width of the periosteal new bone response was proportional to the longitudinal strain at each point around the bone's circumference. It appears that when a bone is loaded in a normal strain distribution, an osteogenic response occurs when peak physiological strains are exceeded. In this situation the amount of new bone formed at each location is proportional to the local surface strain. Cycle numbers between 1200 and 12,000, and cycle frequencies between 10 and 20 Hz have no effect on the bone's adaptive response.     

Measuring arterial strain induced by endovascular stents

Endovascular stents are expandable, fenestrated tubes that are threaded in their collapsed state through an artery to a site of occlusion, plastically enlarged and left as permanent implants to scaffold the artery open. The stent induces large-scale vascular strains that are difficult to measure in vivo and yet can be critical determinants of stent-vessel biology. A method is developed to measure the strain tensor developed on the surface of an artery as a stent is expanded in vivo. Arterial sections are marked with reference points and imaged as the stent is expanded. An axially symmetric parametric model of the artery is determined for each expansion time-point, and these reference points are back-projected onto this surface. The back-projected reference points are grouped and analysed to determine the circumferential, axial and torsional strain tensor components in each arterial subsection. The method is characterised in vitro using bovine artery segments and a latex phantom, and is then tested on rabbits to demonstrate its feasibility in vivo. In vitro experiments on stented bovine arteries show typical post-stenting strains of 0.60, -0.26, and 0.08 mm mm-1 in the circumferential, axial and torsional directions, respectively, sampled every 1 mm along the length of the stented region. Phantom experiments characterise the RMS error of system measurements as 0.1 mm mm-1. The system is shown capable of measuring strains of straight, accessible vessels in the presence of respiratory/cardiac motion and visual glare in vivo.     

A genetic analysis of the hyperthermic response to d-amphetamine in two inbred strains of mice

A genetic analysis of amphetamine-induced hyperthermia was conducted in inbred mice of the strains Balb/c and C₃H and in their F₁F₂ and backcross generations. The results of biometric analysis indicate that the effect of amphetamine on body temperature is genetically determined. The mode of inheritance characterized by a partial dominance (Balb/C over C₃H strain). However, a possible matermal effect of C₃H can overcome the dominant effect in male progenies and inhibit amphetamine hyperthermic effect.     

Differences in the response of Sprague-Dawley and Lewis rats to bezafibrate: The hypolipidemic effect and the induction of peroxisomal enzymes

The effects of bezafibrate administered at 10 and 50 mg/kg/day for 7 days to male Sprague-Dawley (SD) and Lewis rats were investigated in order to determine the interrelation between the changes in serum and hepatic lipid contents and activities of selected peroxisomal, microsomal and mitochondrial enzymes in the two rat strains. In both strains, bezafibrate effectively reduced serum and hepatic lipids, increased the liver weight, induced a proliferation of peroxisomes, and selectively elevated the activities of carnitine acetyltransferase and of the enzymes of the peroxisomal -oxidation system. Moreover, immunoblotting revealed that the drug specifically enhanced the concentration of only those peroxisomal enzymes involved in fatty acid -oxidation. The data obtained demonstrate that although the responses initiated by bezafibrate are qualitatively similar in both strains, they differ in their magnitude in a dose-dependent manner, with the Lewis strain exhibiting a more pronounced response than the SD rats. These results show that dose-dependent strain differences as well as the generally known species differences should be taken into account in pharmacological and toxicological evaluations of fibrates in rodents. Furthermore, generalization and extrapolation from rodent studies should be treated with great caution.     

The ALS Health Profile Study: quality of life of amyotrophic lateral sclerosis patients and carers in Europe

The measurement of functioning and well-being from the perspective of the patient has in recent years become central to the assessment of health and the evaluation of treatment regimes. The past decade has seen an enormous growth in the application of measures designed to assess quality of life in a vast array of medical specialities. However, the use of such measures in neurology has been relatively limited, and this has certainly been the case in amyotrophic lateral sclerosis (ALS). The European ALS Health Profile Study is a longitudinal survey of patients diagnosed with ALS or other motor neurone diseases in which patients are aksed to complete questionnaires concerning their subjective health status. Data from clinical assessments are also collected. It is intended that the information collected will provide more systematic and detailed evidence of the impact of the disease from the perspective of the patient. This contribution documents results from baseline assessment obtained from data supplied by clinicians, carers and patients themselves. Three outcome measured are assessed in this paper: the SF-36, a generic measure of well being and functioning, the ALS Functinal Rating Scale and the Carer Strain Index. The evidence presented here suggests that these measures provide a meaningful and valid picture of the impact of the disease. The data indicate that ALS has substantial adverse effects both upon the functioning and well being of patients and carers, as well as an association between the emotional health status of patients and carers, and between the physical health status of patients and carers. Received: 4 January 2000 / Received in revised form: 15 March 2000 / Accepted: 3 May 2000     

医学成像技术的进展

医学成像技术在最近几年中有了飞速的发展，新的成像方法不断涌现，已有的成像方式不断完善。从平面到立体、从局部到整体、从静态到动态、从形态到功能已成为医学成像技术发展的趋势。文中简要介绍分子成像、近红外热成像等新的成像方式。     

Clinical research on acute lumbar sprain by Qi-inducing acupuncture manipulation

目的:探讨针刺导气法治疗急性腰扭伤的临床价值.方法:将60例急性腰扭伤患者随机单盲分为两组,观察组30例,在针刺得气的基础上施以导气法治疗;对照组30例,在常规针刺得气后留针20 min.3 d后观察疗效.结果:观察组痊愈率为86.7%,对照组为43.3%,观察组痊愈率明显优于对照组(P＜0.01).结论:针刺导气法是治疗腰扭伤的一种较好的方法.     

Previously unrecognized advanced liver disease unveiled by transient elastography in patients with Haemophilia and chronic hepatitis C

Summary. Before the introduction of viral inactivation procedures and viral screening of plasma‐products, haemophiliacs were at high risk of infection with HCV. Those who acquired HCV infection in the 1980s, and are still alive today, may have developed significant liver fibrosis or cirrhosis. However, liver biopsy has not routinely been utilized in the evaluation of haemophiliacs with HCV in Denmark. The aim of this study was to investigate the prevalence of significant fibrosis/cirrhosis among haemophiliacs as evaluated by transient elastography (TE). Cross‐sectional investigation of adult patients with haemophilia A or B. TE with liver stiffness measurements (LSM) ≥8 kPa were repeated after 4–6 weeks. Significant fibrosis and cirrhosis was defined as measurements ≥8 kPa or ≥12 kPa respectively. Among 307 patients with haemophilia A or B registered at the two Haemophilia centres, 141(46%) participate in this study. Forty (28.4%) had chronic hepatitis C, 33 (23.4%) past hepatitis C and 68 (48.2%) had never been infected, at screening LSM ≥8 kPa were found in 45.7%, 24.7% and 4.6% respectively. Among patients with chronic hepatitis C significant fibrosis was confirmed in 17.1% and cirrhosis in 2.9% by repeated LSM ≥8 and ≥12 kPa respectively. The median TE‐value in never HCV‐infected haemophiliacs was comparable with what has been found in healthy non‐haemophiliacs. In Danish haemophiliacs where liver biopsy has not routinely been used for assessing severity of liver fibrosis, LSM identified advanced liver disease in one‐fifth of cases that had not been recognized during clinical follow‐up.     

Effect of Transmural Extent of the Simulated Infarction in a Left Ventricular Model on Displacement and Strain Distribution Estimated from Synthetic Ultrasonic Data

The identification of a sub-endocardial infarction is of major interest in cardiology. This study evaluates the sensitivity of selected measures to the thickness of such an infarction. Synthetic ultrasonic data (long-axis view) of left ventricular models with inclusions were generated using Field II and meshes obtained from finite-element simulations, which also provided the reference for the estimates obtained from ultrasonic data. The displacements, the first and second component of the principal strain (ε₁ and ε₂), and several measures derived from these quantities were estimated. All estimates, except for the poorly estimated ε₂, exhibited sensitivity to the presence and transmurality of the inclusion. The most sensitive was the gradient of the averaged transmural profiles of ε₁, and ε₁ averaged over the area corresponding to the transmural inclusion. The inflection point of the ε₁ profile shifted toward the outer wall with increasing thickness of the non-transmural inclusion.