计算女性青年人体环节体积的二元回归方程

目的：直接测算女性青年人体各环节体积。方法：采用CT-图像分析法，对50例女性样本(18—23岁)进行全身CT-横断层扫描、影像分析和测算。结果：获得了样本各环节的长度和体积等惯性数据并建立了以身高、体重为自变量的直接计算青年人体各环节体积的二元回归方程。结论：为直接确定女性青年人体的体积分布提供了可靠的手段。     

计算中国男性人体环节质量的多元回归方程

目的：确定中国男性青年人体惯性参数模型，建立直接计算中国男性青年人体各环节质量的多元回归方程。方法：采用CT图像分析仪测算法，对中国男性样本(18～23岁)进行体态参数测定、全身CT横断层扫描、影像分析、数据测算并进行逐步回归，筛选、确定重要变量。结果：设计了由15个环节组成的中国男性青年人体数学模型，建立了以身高，体重，环节长度、宽度、围度等为自变量的直接计算中国男性青年人体各环节质量的多元回归方程。结论：为直接计算中国男性青年人体整体及各环节的质量提供了可靠的手段。     

计算中国男性人体体段转动惯量的多元回归方程的研究

目的测算并确定中国男性青年人体惯性参数及其数学模型,建立计算中国男性青年人体体段转动惯量的多元回归方程。方法采用CT—图像分析仪测算法,对50例中国男性样本(18～23岁)进行体态参数测定、全身CT横断层扫描、影像分析、测算,并进行逐步回归分析。结果获得了50例中国男性青年人体样本各体段转动惯量数据,设计了由15个体段组成的中国男性青年人体数学模型,并据此推导、建立了以身高,体重,体段长度、宽度、围度等为自变量的直接计算中国男性青年人体转动惯量的多元回归方程。结论为直接从个体的体态参数来推算人体各体段的转动惯量参数提供了可靠的手段。     

Development of a mechanical testing assay for fibrotic murine liver

In this article, a novel protocol for mechanical testing, combined with finite element modeling, is presented that allows the determination of the elastic modulus of normal and fibrotic murine livers and is compared to an independent mechanical testing method. The novel protocol employs suspending a portion of murine liver tissue in a cylindrical polyacrylamide gel, imaging with a microCT, conducting mechanical testing, and concluding with a mechanical property determination via a finite element method analysis. More specifically, the finite element model is built from the computerized tomography (CT) images, and boundary conditions are imposed in order to simulate the mechanical testing conditions. The resulting model surface stress is compared to that obtained during mechanical testing, which subsequently allows for direct evaluation of the liver modulus. The second comparison method involves a mechanical indentation test performed on a remaining liver lobe for comparison. In addition, this lobe is used for histological analysis to determine relationships between elasticity measurements and tissue health. This complete system was used to study 14 fibrotic livers displaying advanced fibrosis (injections with irritant), three control livers (injections without irritant), and three normal livers (no injections). The moduli evaluations for nondiseased livers were estimated as 0.62 +/- 0.09 kPa and 0.59 +/- 0.1 kPa for indenter and model-gel-tissue (MGT) assay tests, respectively. Moduli estimates for diseased liver ranged from 0.6-1.64 kPa and 0.96-1.88 kPa for indenter and MGT assay tests, respectively. The MGT modulus, though not equivalent to the modulus determined by indentation, demonstrates a high correlation, thus indicating a relationship between the two testing methods. The results also showed a clear difference between nondiseased and diseased livers. The developed MGT assay system is quite compact and could easily be utilized for controlled evaluation of soft-tissue moduli as shown here. In addition, future work will add the correlative method of elastography such that direct controlled validation of measurement on tissue can be determined.     

Precise measurement of vertebral bone density using computed tomography without the use of an external reference phantom

Bone density measurement by quantitative computed tomography (QCT) commonly uses an external reference phantom to decrease scan-to-scan and scanner-to-scanner variability. However, the peripheral location of these phantoms and other phantom variables is also responsible for a measurable degradation in accuracy and precision. Due to non-uniform artifacts such as beam hardening, scatter, and volume averaging, the ideal reference phantom should be as close to the target tissue as possible. This investigation developed and tested a computer program that uses paraspinal muscle and fat tissue as internal reference standards in an effort to eliminate the need for an external phantom. Because of their proximity, these internal reference tissues can be assumed to reflect more accurately the local changes in the x-ray spectra and scatter distribution at the target tissue. A user interactive computerized histogram plotting technique enabled the derivation of reproducible CT numbers for muscle, fat, and trabecular bone. Preliminary results indicate that the use of internal reference tissues with the histogram technique may improve reproducibility of scan-to-scan measurements as well as inter-scanner precision. Reproducibility studies on 165 images with intentional region-of-interest (ROI) mispositioning of 1.5, 2.5, or 3.5 mm yielded a precision of better than 1% for normals and 1% to 2% for osteoporotic patients--a twofold improvement over the precision from similar tests using the standard technique with an external reference phantom. Such improvements in precision are essential for QCT to be clinically useful as a noninvasive modality for measurement of the very small annual changes in bone mineral density.     

Development of an artificial vertebral body using a novel biomaterial,hydroxyapatite/collagen composite

Hydroxyapatite/collagen (HAp/Col) composites having a bone-like nanostructure were synthesized and shaped into implants. This study was designed to develop an artificial vertebra system using this novel implant for anterior fusion of the cervical spine. Anterior fusion was carried out on 6 beagle dogs with the implants adsorbing rhBMP-2 (400 microg/ml). and 9 dogs with the implants without rhBMP-2. In 3 dogs of the rhBMP-treated group, as well as 6 dogs of the non-rhBMP-treated group, the implant was fixed with a poly-L-lactide plate and 2 titanium screws. Implants were taken out after 13 weeks from each 3 dogs in the rhBMP(-):plate(-). rhBMP(-):plate(+) and rhBMP(+):plate(+) groups. Also, the implants were removed from each 3 dogs in the rhBMP(-):plate(+) and rhBMP(+):plate(+) groups after 24 weeks. Histological and radiographical analysis suggested that since the larger part of the composite material was absorbed within 13 weeks, reduction of the intervertebral distance was caused, and that enhancement of callus formation and bone bridging by rhBMP-treatment was effective to prevent collapse of the implant, even though an effect of anterior plate-fixation was not obvious. The HAp/Col implant adsorbing rhBMP-2 may be a suitable replacement for the existing ceramics in anterior interbody fusion of the cervical spine.     

Comparison of linear regression and probit analysis for detecting H-reflex threshold in individuals with and without spinal cord injury

A major challenge to understanding spinal reflex organization in health and disease is identifying sensitive measures of reflex excitability. The purpose of this study was to determine whether linear regression or probit analysis techniques are more sensitive for detecting H-reflex and M-wave threshold and for identifying differences in H-reflex threshold in individuals with and without spinal cord injury (SCI). Soleus H-reflex recruitment curves were generated in 9 individuals with SCI and 20 able-bodied individuals. H-reflex and M-wave threshold was estimated using three different methods, two that used linear regression of H-reflex peak-to-peak amplitude and one that used probit analysis of quantal H-reflexes. Results indicate that in both groups all three techniques were equally sensitive for detecting H-reflex but not M-wave threshold. When H-reflex threshold was normalized to M-wave threshold, different techniques provided different estimates of H-reflex threshold. However, between-group differences (SCI vs. able-body) in H-reflex and M-wave threshold were not affected by the measurement techniques that were compared in this study. We conclude that these techniques provide equally sensitive estimates of H-reflex but not M-wave threshold in persons with and without SCI. Hence, caution should be used when interpreting normalized and non-normalized values of H-reflex threshold.     

Development and pilot testing of a disease management program for low literacy patients with heart failure

Development and pilot testing of a disease management program for low literacy patients with heart failure. BACKGROUND: Randomized trials have shown that disease management programs can reduce hospitalizations and improve symptoms for patients with congestive heart failure. We sought to create and pilot test such a program for patients with low literacy skills. METHODS: We used focus groups and individual cognitive response interviews (CRIs) to develop an educational booklet for low literacy patients with heart failure. We incorporated the booklet into a disease management intervention that also included an initial individualized 1-h educational session and scheduled supportive phone calls that were tapered over 6 weeks. We then conducted a 3-month before-after study on patients with low literacy skills (<9th grade literacy level) in a university internal medicine clinic to test the acceptability and efficacy of our program. Outcomes of interest included heart failure-related knowledge, self-care behavior and heart failure-related symptoms measured on the Minnesota Living with Heart Failure (MLwHF) scale. RESULTS: Twenty-five patients were enrolled and 23 (92%) completed 3-month follow-up. Mean age was 60 years (range 35-74), 60% were men, 60% were African-American, and 74% had household income under $15,000 per year. The median reading level was fifth grade with 32% reading at or below the third grade level. Mean knowledge score at baseline was 67% and did not improve after the intervention. The proportion of patients reporting weighing themselves daily increased from 32% at baseline to 100% at 12 weeks. Mean improvement on the MLwHF scale was 9.9 points over the 3-month trial (95% CI: 0.5, 19.2), which corresponds to an improvement in one class on the New York Heart Association heart failure scale. CONCLUSION: A heart failure disease management program designed specifically for patients with low literacy skills is acceptable and is associated with improvement in self-care behavior and heart failure related symptoms.     

A layer-specific three-dimensional model for the simulation of balloon angioplasty using magnetic resonance imaging and mechanical testing

A detailed understanding of the mechanical procedure of balloon angioplasty requires three-dimensional (3D) modeling and efficient numerical simulations. We have developed a 3D model for eight distinct arterial components associated with specific mechanical responses. The 3D geometrical model is based on in vitro magnetic resonance imaging of a human stenotic postmortem artery and is represented by nonuniform rational B-spline surfaces. Mechanical tests of the corresponding vascular tissues provide a fundamental basis for the formulation of large strain constitutive laws, which model the typical anisotropic, highly nonlinear, and inelastic mechanical characteristics under supraphysiological loadings. The 3D finite-element realization considers the balloon–artery interaction and accounts for vessel-specific axial in situ prestretches. 3D stress states of the investigated artery during balloon expansion and stent deployment were analyzed. Furthermore, we studied the changes of the 3D stress state due to model simplifications, which are characterized by neglecting axial in situ prestretch, assuming plane strain states, and isotropic material responses, as commonly utilized in previous works. Since these simplifications lead to maximum stress deviations of up to 600%—where even the stress character may interchange—the associated models are, in general, inappropriate. The proposed approach provides a tool that has the potential (i) to improve procedural protocols and the design of interventional instruments on a lesion-specific basis, and (ii) to determine postangioplasty mechanical environments, which may be correlated with restenosis responses. © 2002 Biomedical Engineering Society. PAC2002: 8719Rr, 8761Lh, 8710+e     

Assessing the analytic validity of molecular testing for Huntington disease using data from an external proficiency testing survey

PurposeDocumenting high analytic validity of the molecular diagnostic test for Huntington disease is important because of counseling implications. This dominantly inherited adult onset disorder (prevalence of three or more per 100,000) is characterized by chorea, ataxia, and personality changes. The molecular basis is excessive CAG repeats in the HTTgene.MethodsExternal proficiency testing survey results for Huntington disease were extracted (2003–2010). Analytic interpretations and CAG repeat lengths were compared with published performance criteria.ResultsBetween 2008 and 2010, 33 US participating laboratories reported clinical test interpretations. Analytic validity was high (sensitivity: 99.5%, 95% confidence interval: 97.1–99.9%; specificity: 99.2%, 95% confidence interval: 97.1–99.9%). Repeat length errors occurred in 2.6% (95% confidence interval: 1.8–3.8%) of 1,060 allelic challenges, with most being minor or from a single participant. Past performance (2003–2007) was similar. The 23 international participants had more total repeat length errors (17.5%, 95% confidence interval: 14.6–20.7%). Further analyses indicated that assessment criteria can be relaxed without jeopardizing analytic validity.ConclusionAnalytic validity is high for Huntington disease testing among US laboratories. International survey participants had lower analytic validity and a higher proportion of poorly performing laboratories. The reasons for this are unclear.Genet Med 2012:14(1):69–75     

Development of a heart failure filter for Medline: an objective approach using evidence-based clinical practice guidelines as an alternative to hand searching

Background  

Heart failure is a highly debilitating syndrome with a poor prognosis primarily affecting the elderly. Clinicians wanting timely access to heart failure evidence to provide optimal patient care can face many challenges in locating this evidence.     

Development of an animal experimental model for a bileaflet mechanical heart valve prosthesis

The objective of this study was to develop a pre-clinical large animal model for the in vivo hemodynamic testing of prosthetic valves in the aortic position without the need for cardiopulmonary bypass. Ten male pigs were used. A composite valved conduit was constructed in the operating room by implanting a prosthetic valve between two separate pieces of vascular conduits, which bypassed the ascending aorta to the descending aorta. Prior to applying a side-biting clamp to the ascending aorta for proximal grafting to the aortic anastomosis, an aorta to femoral artery shunt was placed just proximally to this clamp. The heart rate, cardiac output, Vmax, transvalvular pressure gradient, effective orifice area and incremental dobutamine stress response were assessed. A dose-dependent increase with dobutamine was seen in terms of cardiac output, Vmax, and the peak transvalvular pressure gradient both in the native and in the prosthetic valve. However, the increment was much steeper in the prosthetic valve. No significant differences in cardiac output were noted between the native and the prosthetic valves. The described pre-clinical porcine model was found suitable for site-specific in-vivo hemodynamic assessment of aortic valvular prosthesis without cardiopulmonary bypass.     

Development of a new concept automatic frequency controller for an ultrasmall C-band linear accelerator guide

We are developing a four-dimensional, image-guided radiotherapy system with a gimbaled x-ray head. The system has pursuing irradiation capability in addition to precise irradiation capability, owing to its agile x-ray head. The moving x-ray head requires a very small C-band accelerator guide. The heat intensity of the accelerator guide is much higher than that of conventional S-band medical linear accelerators. The resonance frequency varies over almost 1.0 MHz with a thermal time constant of about 30 s. An automatic frequency controller (AFC) is employed to compensate for this variation in resonance frequency. Furthermore, we noted that fast AFC response is important for step-and-shoot intensity modulation radiotherapy (IMRT), in which the beam is turned on and off frequently. Therefore, we invented a digital AFC, based on a new concept, to provide effective compensation for the thermal characteristics of the accelerator guide and to ensure stable and optimized x-ray treatment. An important aspect of the performance of the AFC is the capture-frequency range over which the AFC can seek, lock on to, and track the resonance frequency. The conventional, analog AFC used in S-band medical linear accelerators would have a capture-frequency range of about 0.9 MHz, if applied to our accelerator guide, and would be inappropriate. Conversely, our new AFC has a capture-frequency range of 24 MHz, which is well suited to our accelerator guide. The design concept behind this new AFC has been developed and verified. A full prototype system was constructed and tested on an existing accelerator guide at the rated x-ray output (500 cGy/min) of our radiotherapy system, with a pulse-repetition frequency of 300 Hz. The AFC acquired the resonance frequency of the accelerator guide within 0.15 s after beam-on, and provided stable tracking and adjustment of the frequency of the microwave source to the resonance frequency of the accelerator guide. With a planned improvement of the initialization of the AFC it should be able to acquire the resonance frequency within 33 ms.     

Corneal reinforcement using an acellular dermal matrix for an analysis of biocompatibility, mechanical properties, and transparency

The aim of this study was to analyze the viability of using an acellular dermal matrix (ADM) as a reinforcement material for peripheral corneal thinning disease. The complete removal of cell components was confirmed by hematoxylin and eosin (H&E) and 4',6-diamidino-2-phenylindole (DAPI) staining. Transmission electron microscopy determined that the stromal structure was well preserved. Uniaxial tests revealed that the ADM had strong mechanical properties. After being implanted into rabbit cornea the ADM showed no sign of rejection and even achieved good transparency 24weeks post-surgery. H&E staining demonstrated that keratocytes grew in the ADM and the ADM-cornea interface became blurry. Picrosirius red staining revealed great changes of collagen in the ADM. Uniaxial testing of the reinforced cornea showed better mechanical strength than the normal rabbit cornea, but this did not exhibit statistical significance. These results suggest that ADM is a worthy candidate for future exploration as a reinforcement material for peripheral corneal thinning problems.     

Analysis of tissue optical coefficients using an approximate equation valid for comparable absorption and scattering.

New photosensitizers activated by longer wavelengths than 630 nm light used with Photofrin II are under evaluation by various groups for the treatment of malignancies. Any increase in tumour volume destroyed by these agents as compared to Photofrin II will be partly determined by tissue penetrance at the longer wavelengths. Attenuation coefficients were measured for various tissues at 630 nm and the more penetrative near infrared wavelength of 789 nm. A new model of light propagation in tissue is shown to be accurate for arbitrary ratios of absorption and scattering, by comparison with a rigorous solution to the transport equation. Absorption and transport scattering coefficients of tissues at 630 and 789 nm were obtained by fitting this model to optical attenuation measurements. In vitro tissues included bovine heart, kidney and tongue, pig liver and fat, and chicken muscle; in vivo tissues included Dunning R3327-AT and R3327-H tumours. The penetration depth was found to be 1.35-2.25 times greater at 789 than 630 nm, depending on tissue type. The greatest differences in penetration between the two wavelengths were in the highly pigmented tissues. These substantial increases in penetration in the infrared may be important in future applications of photodynamic therapy.     

Development of an immunochromatographic strip assay for ractopamine detection using an ultrasensitive monoclonal antibody

A sensitive gold nanoparticle immunochromatographic strip assay and indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) were developed for the detection of ractopamine (RCT), a beta-adrenergic agonist. The immunogen and coating antigen were synthesized by the carbodiimide method and conjugated with keyhole limpet hemocyanin and ovalbumin, respectively. The highly sensitive and specific monoclonal antibody was prepared for RCT, with a 50% inhibition concentration of 0.05?ng/ml and had no cross-reactivity with other beta-adrenergic agonists. An ultrasensitive and rapid immunochromatographic strip assay was developed with an RCT cutoff value of 2?ng/ml. Both developed methods can be used for RCT detection in swine urine.     

Photonuclear target systems for producing clinically useful quantities of 11C using an electron linear accelerator

Described in this paper are what we believe to be the first practical photonuclear target systems for production of 11C containing CO and CO2 using bremsstrahlung produced from an electron linear accelerator similar to certain radiotherapy accelerators. This is a continuation of work reported earlier concerning a similar target system presently being used for production of 15O-O2. The 11C producing systems utilized liquid carbon dioxide, liquid cyclohexane, and liquid glacial acetic acid target materials. The carbon dioxide and glacial acetic acid target materials produced principally a 11C-CO product material. The cyclohexane target material produced a 11C-hydrocarbon product which was then oxidized to CO2. Target activity yields for these systems, normalized to a 20-cm-long by 10-cm-diam target chamber irradiated in a bremsstrahlung field produced by a 26-MeV, 100-microA electron beam, were 1.9 X 10(8) Bq (5 mCi) at 7.4 X 10(8) Bq g-1 (20 mCi g-1) for carbon dioxide, 1.4 X 10(8) Bq (3.8 mCi) at 3.7 X 10(10) Bq g-1 (1 Ci g-1) for cyclohexane, and 7.4 X 10(8) Bq (20 mCi) at 3.7 X 10(10) Bq g-1 (1 Ci g-1) for glacial acetic acid.     

Development of an ectopic site for islet transplantation, using biodegradable scaffolds

Clinical islet transplantation in liver has achieved normoglycemia. However, this site may not be ideal for islet survival. To create a more optimal site for islet transplantation, we have developed a construct with biodegradable scaffolds. Islets were seeded in scaffolds and transplanted into the epididymal fat pad of diabetic BALB/c mice. Controls included islets transplanted underneath the kidney capsule or into the fat pad without scaffolds. All animals with islets in scaffolds or the kidney became normoglycemic and maintained this metabolic state. When islets were transplanted without scaffolds the time to achieve normoglycemia was significantly increased and less than 45% of mice survived. An oral glucose tolerance test was performed on the scaffold and kidney groups with similar blood glucose levels and area under the curve values between the groups. Grafts were removed at more than 100 days posttransplantation and all animals became hyperglycemic. There was no significant difference in insulin content between the grafts and all grafts were well vascularized with insulin-positive beta cells. Therefore, islets in scaffolds function and restore diabetic animals to normoglycemic levels, similar to islets transplanted underneath the kidney capsule, suggesting scaffolds can be used to create a site for islet transplantation.