三维重建及3D打印技术在骨盆三维特征测量准确性研究

目的　研究分析尸体骨盆与其三维重建数字化模型及3D打印实体模型的三维特征测量结果差异。 方法　选择1具中年男性骨盆标本,根据骨盆的生理学结构特点在骨盆标本表面选取并固定共计14个特征点,并使用三坐标仪测量并记录特征点的三维坐标;使用CT设备对固定了特征点的骨盆标本进行1.0 mm的断层扫描;使用三维医学图像软件（Delta Medical Studio,DMS）对获取的扫描图像进行三维重建,并记录特征点的三维坐标;使用3D打印设备（熔融沉积成型,FDM）及光固化成型（Stereo Lithography Appearance,SLA）打印三维重建模型,三坐标仪测量记录特征点的三维坐标;通过记录的三维坐标分别计算尸体标本、数字模型、3D打印实体模型的特征点之间的距离及夹角;从最大误差、平均误差、t值验证等角度分析三组数据的误差情况。 结果　三维重建数字化骨盆模型的特征测量距离的平均误差约为0.5 mm,角度平均误差约为0.35 o;3D打印模型相对于骨盆标本的距离测量的平均误差约为0.8~1.1 mm,角度平均误差约为0.4°~0.5°。 结论 三维重建模型和3D打印实体模型对于骨盆术前的参考及测量精度方面具备可靠性,可根据实际需求选择3D打印模型作为骨盆术前规划的参考。     

三维重建及3D打印技术在骨盆三维特征测量准确性研究

目的　研究分析尸体骨盆与其三维重建数字化模型及3D打印实体模型的三维特征测量结果差异。 方法　选择1具中年男性骨盆标本,根据骨盆的生理学结构特点在骨盆标本表面选取并固定共计14个特征点,并使用三坐标仪测量并记录特征点的三维坐标;使用CT设备对固定了特征点的骨盆标本进行1.0 mm的断层扫描;使用三维医学图像软件（Delta Medical Studio,DMS）对获取的扫描图像进行三维重建,并记录特征点的三维坐标;使用3D打印设备（熔融沉积成型,FDM）及光固化成型（Stereo Lithography Appearance,SLA）打印三维重建模型,三坐标仪测量记录特征点的三维坐标;通过记录的三维坐标分别计算尸体标本、数字模型、3D打印实体模型的特征点之间的距离及夹角;从最大误差、平均误差、t值验证等角度分析三组数据的误差情况。 结果　三维重建数字化骨盆模型的特征测量距离的平均误差约为0.5 mm,角度平均误差约为0.35 o;3D打印模型相对于骨盆标本的距离测量的平均误差约为0.8~1.1 mm,角度平均误差约为0.4°~0.5°。 结论 三维重建模型和3D打印实体模型对于骨盆术前的参考及测量精度方面具备可靠性,可根据实际需求选择3D打印模型作为骨盆术前规划的参考。     

A three dimensional approach for quantifying resultant loading at the knee

Background

Clinical effectiveness of lateral wedges for knee osteoarthritis is inconsistent across studies. One explanation is that knee loading is not fully described by the peak frontal-plane knee moment. The purpose of this study was to propose a 3D resultant approach to describing moments at the knee and evaluate how this moment changes in response to lateral wedges.

Examination of spinal column vibrations: a non-invasive approach

Summary Accelerations of vertebrae during whole-body vibration (WBV) are used in occupational biomechanics for the prediction of internal stress. To avoid invasive techniques, a method for the calculation of bone accelerations was developed using measurements on the skin. The soft tissue between spinous processes L3 and T5 and miniature accelerometers stuck to the skin over them was modelled by a simple Kelvin element, whose parameters i.e. angular natural frequency _n4 and critical damping describe an approximate transfer function between the bone (input) and the skin surface (output). The parameters were determined from free damped oscillations of the accelerometer-skin complex in the Z-axis, and depended significantly on the factors subject and point of measurement. In one subject, the time courses of bone accelerations during sinusoidal WBV (4.5 and 8 Hz; 1.5 m·s^–2 RMS) were calculated using separate transfer functions for each of 11 different spinal levels. Since the output signals on the skin were non-sinusoidal, the skin accelerations had to be treated with an inverse transfer function in the frequency domain. A comparison of accelerations measured on the skin and predicted for the bone mainly indicates that absolute peak values of bone accelerations are smaller and occur earlier. Both kinds of acceleration hint at differences in WBV-induced internal stress within the spine.     

The molecular basis of allergenicity: comparative analysis of the three dimensional structures of diverse allergens reveals a common structural motif.

BACKGROUND: Although a large number of allergens have been characterised, the structural, functional, and biochemical features that these molecules have in common, and that could explain their ability to elicit powerful IgE antibody responses, are still uncertain. Recently, there has been considerable interest in the role of the cysteine protease activity of the house dust mite allergen Der p 1 in biasing the immune response in favour of IgE production. AIMS:To search for remote homologues of Der p 1 with sequences similar to the 30 conserved amino acids surrounding the catalytic cysteine residue (Cys34). METHODS: Potential homologues were analysed by examining their three dimensional structures and multiple sequence alignments using the programs PROPSEARCH, ClustalW, GeneDoc, and Swiss Pdb Viewer. RESULTS: Diverse allergens (for example, the plant cysteine protease papain, the transport protein lipocalin Mus m 1, and the ragweed allergen Amb a 5) have a similar structural motif; namely, a groove resembling the substrate binding groove of Der p 1. The groove is located inside an alpha-beta motif, between an alpha helix on one side and an antiparallel beta sheet on the other side. A similar common motif (a cysteine stabilised alpha-beta fold) can also be found in some toxins and defensins. CONCLUSION: Allergens of diverse sources have a common structural motif, namely a groove located inside an alpha-beta motif, which could potentially serve as a ligand binding site.     

Detection of maedi-visna virus in the kidneys of naturally infected sheep

Infections with maedi-visna virus (MVV) cause progressive inflammation in different organs, mainly the lung, mammary gland, brain and joints. The aim of the present study was to investigate whether the kidney represents a viral target in natural MVV infection. For this, kidney samples from 13 sheep naturally infected with MVV were examined by histology, polymerase chain reaction (PCR), and immunohistochemistry. The kidneys of nine animals showed membranoproliferative glomerulonephritis and interstitial nephritis. The inflammatory infiltrate consisted of lymphocytes, plasma cells and macrophages. Interestingly, lymphoid follicles resembling those known to occur in other MVV-infected tissues were observed. Lung tissue from the same animals had typical MVV lesions, such as lymphofollicular hyperplasia and interstitial pneumonia. Maedi-visna proviral DNA sequences were detected in renal and lung tissue samples from these nine sheep by PCR, and the specificity of the amplified products was further verified by DNA sequencing. Moreover, MVV-specific immunohistochemistry revealed viral antigen in affected kidneys and lungs. These results suggest that the kidney may be a common target in natural MVV infection, and raise the issue of the role of this organ in the disease.     

Distribution of the neural crest cells in the heart of birds: a three dimensional analysis

Summary The distribution of neural crest derived cells (NC) in the heart of quail-chick chimeric embryos was analyzed three-dimensionally after computer reconstruction. During the division of the truncus arteriosus into the aorta and the pulmonary trunk, ventral and dorsal columns of NC-derived cells were found in the truncal swellings. These columns were elongations from the aorticopulmonary (AP) septum. The dorsal column extended more proximally than did the ventral column. Around hatching, NC-derived cells located between the proximal aorta and the pulmonary trunk, differentiated into cartilage and connective tissue. They formed a part of the cardiac skeleton. A small number of NC-derived cells were scattered in the cusps of the arterial valves. Cells derived from the right NC were located around the aorta and the right arch arteries but not around the distal pulmonary trunk and the left arch arteries. At the proximal level, cells derived from the rigth NC were located in both the dorsal and ventral columns. These results suggest that the AP septum is mainly formed by NC-derived cells, right and left NC cells migrating into assigned areas in the heart. Location of two columns of NC-derived cells may support a translocation hypothesis for the AP septum during truncal division.     

Accessory muscle in the hypothenar region: a functional approach.

An accessory muscle was found in the hypothenar region on both hands during routine cadaver dissection. This muscle originated from the tendon of the flexor carpi radialis, crossed the palma manus region superficially and inserted together with the abductor digiti minimi muscle into the ulnar aspect of the basis of the fifth proximal phalanx. The muscle was supplied by one branch arising from the main trunk of the ulnar nerve. Abnormalities of the hypothenar muscles have been described by many authors with a focus on their structural aspects, but there is not enough data about the possible functions they could induce. In our study, we try to elucidate the functions of this accessory muscle. We did not name the variant muscle as it has various functions, each similar to that of individual hypothenar muscles.     

Three dimensional stress analysis of diabetic insole: a finite element approach.

Current research in foot biomechanics includes studies on prevention of recurrence of neuropathic foot ulcers. This paper attempts to prescribe accommodative insoles, which reduce plantar pressure levels particularly under the hallux. There is little quantitative information available regarding the effects of insole materials on reduction of plantar pressure. The insole models available in the literature are mostly two-dimensional (2-D). Hence, there is a need to develop a 3-D model with actual geometry which includes sufficient details. In this study a three-dimensional (3-D) model of the insole was constructed. A linear and non-linear static analysis using finite element method (FEM) was performed. Results were compared for different materials such as Silicon Gel, Plastozot, Polyfoam, and Ethinil Vinyl Acetate (EVA). Our 3-D finite element model was constructed using 16170 ten-node tetrahedral, mixed U-P (displacement-pressure), hyperelastic, solid elements. Four different hyperelastic and foam materials were used and compared and the loading condition was based on the mid-stance phase of the gait. This research has shown that most of these materials are very effective in terms of reduction of plantar stress concentrations. The technique used in this research provides a promising approach to understanding of behavior of insole materials and suggests a design guideline for therapeutic footwear and orthoses.     

Exploring the borders of the schizoaffective spectrum: a categorical and dimensional approach

BACKGROUND: Schizoaffective disorder has long been considered as an intermediate condition between major mood disorders and schizophrenia, however, the nature of the relationship to these diagnoses remains unclear. We aimed at examining the nature of such a relationship in a mixed sample of psychotic disorders by using a dimensional and categorical approach to psychopathology. METHODS: Six-hundred and sixty psychotic inpatients were assessed for lifetime ratings of mania, depression, psychosis and incongruence, diagnosed according to Research Diagnostic Criteria, and classified as having nonaffective psychosis without mood syndromes (n=429), nonaffective psychosis with mood syndromes (n=101), schizoaffective disorder mainly schizophrenic (n=41), schizoaffective disorder mainly affective (n=42) or mood disorder with psychotic symptoms (n=47). We tested for associations of illness-related features including risk factors, premorbid, clinical and outcome variables with classes of disorders and lifetime ratings of psychopathology, and examined the relative contribution of categorical and dimensional representations of psychopathology in explaining disease characteristics. RESULTS: While categories at the extreme end of the psychotic spectrum meaningfully differed across a number of the illness-related variables, no substantial discontinuity was apparent between adjacent categories of psychotic disorders. Risk factors, premorbid adjustment, clinical features and impairment appeared to be present in a mostly monotonic continuous fashion from nonaffective psychoses to mood disorders with psychotic features. The overall association pattern of illness-related variables with mood and psychotic syndromes was largely independent of specific diagnostic categories, and the dimensional approach was neatly superior to the traditional diagnostic approach in explaining the characteristics of the illness. LIMITATIONS: This was a cross-sectional study with retrospective assessment of illness-related-variables and lifetime psychopathology. CONCLUSION: The results are compatible with the notion of the schizoaffective spectrum and with a continuum model of the psychotic illness.     

Experiential avoidance as a functional dimensional approach to psychopathology: an empirical review

The construct of experiential avoidance has become more frequently used by clinical researchers. Experiential avoidance involves the unwillingness to remain in contact with private experiences such as painful thoughts and emotions and is often proposed to be critical to the development and maintenance of psychopathology. This review summarizes the empirical studies on experiential avoidance as a factor in the etiology of maladaptive behavior and its relationship to specific diagnostic categories. Although some of the current literature suggests that experiential avoidance may be implicated in various forms of psychopathology, a fundamental limitation of this research is the lack of theoretical integration and refinement with regard to operationalizing and assessing experiential avoidance. Future studies should attempt to understand the core processes involved in experiential avoidance better, and then clearly operationalize the construct and determine its incremental validity relative to other constructs.     

The child bipolar questionnaire: a dimensional approach to screening for pediatric bipolar disorder

BACKGROUND: The Child Bipolar Questionnaire (CBQ) is a rapid screener with a Core Index subscale of symptom dimensions frequently reported in childhood-onset bipolar disorder (BD) and scoring algorithms for DSM-IV BD, with and without attention-deficit/hyperactivity disorder (ADHD), and the proposed Narrow, Broad, and Core phenotypes. This report provides preliminary data on the reliability and validity of the CBQ. METHOD: Test-retest and inter-rater reliability of the CBQ were assessed. The ability of CBQ screening diagnoses and of the CBQ Core Index subscale to effectively predict diagnostic classification by structured interview was assessed using the K-SADS P/L. RESULTS: Preliminary test-retest data showed excellent reliability for both the CBQ total score (r = 0.82) and the Core Index subscale (r = 0.86). Preliminary validity data was also promising. CBQ screening algorithms performed with a specificity of 97% and a sensitivity of 76% in classifying subjects with K-SADS P/L diagnosis of BD vs. no BD. The Core Index subscale had excellent agreement with K-SADS P/L diagnosis (k = 0.84) in classifying BD, ADHD-only, and no diagnosis and demonstrated 100% sensitivity and 86% specificity in classifying BD vs. no BD. LIMITATIONS: This preliminary data is from a sample enriched with bipolar disorder cases. Further validation is needed with samples in which childhood-onset BD is rarer and diagnoses more diverse. CONCLUSIONS: The CBQ shows potential for rapid and economically feasible identification of possible childhood-onset BD cases as defined by DSM-IV criteria as well as by alternate disease phenotypes. Further validation studies will focus on inpatient and outpatient samples with a broader range of variability.     

Early ontogeny of catecholaminergic structures in the sheep brain

Summary The localization of tyrosine hydroxylase was studied in the brain of sheep foetus during early ontogeny using immunohistochemistry. The first immunoreactive neurons appeared very early since they were found on day 30 of pregnancy in the medioventral part of the mesencephalic flexure. The distribution of the different catecholaminergic groups of neurons was similar to the adult's after 75 days of pregnancy. The latest group to appear was the A₁₂ group.Comparison of the development of the sheep foetus with rodents or primates, more commonly studied, is difficult because of its different development. It seems, however, that catecholaminergic structures appear earlier in sheep and rodents than in human. Considering the early appearance of these transmitters in the central nervous system, their role on brain development has to be studied in the futureAbbreviations used in the text ACTH adrenocorticotropin hormone - BSA bovine serum albumin - FLM fascicules longitudinales mediales - FITC fluorescein isothiocyanate - FSH follicle stimulating hormone - LH luteinizing hormone - LPH lipotropin hormone - PBS phosphate buffered saline - TH tyrosine hydroxylase - TH-IR tyrosine hydroxylase immunoreactive Abbreviations used in the figures AI adhesio interthalamica - BO bulbus olfactorius - CA commissura anterior - Cer cerebellum - cf cervical flexure - ChO chiasma opticum - CM corpus mamillare - COL colliculi - CP commissura posterior - Ep epiphysis (pineal gland) - FMT fasciculus mamillothalamicus - FR fasciculus retroflexus - Hyp hypophysis;mf, mesencephalic flexure - NO nervus opticus - P pons - pf pontic flexure;tg, tongue - I-II lateral ventricles - III third ventricle - IV fourth ventricle     

Simulation model of cardiac three dimensional accelerometer measurements

A miniaturized accelerometer sensor attached to the heart may be applied for monitoring cardiac motion. Proper understanding of the sensor measurements is required for successful development of algorithms to process the signal and extract clinical information. In vivo testing of such sensors is limited by the invasive nature of the procedure. In this study we have developed a mathematical simulation model of an accelerometer attached to the heart so that testing initially may be performed on realistic, simulated measurements. Previously recorded cardiac motion by sonomicrometric crystals was used as input to the model. The three dimensional motion of a crystal attached to the heart served as the simulated motion of the accelerometer, providing the translational acceleration components. A component of gravity is also measured by the accelerometer and fused with the translational acceleration. The component of gravity along an accelerometer axis varies when the axis direction slightly rotates as the accelerometer moves during the cardiac cycle. This time-varying gravity component has substantial effects on the accelerometer measurements and was included in the simulation model by converting the motion to prolate spheroidal coordinates where the axis rotation could be found. The simulated accelerometer signal was filtered and integrated to velocity and displacement. The resulting simulated motion was consistent with previous accelerometer recordings during normal and ischemic conditions as well as for alterations of accelerometer orientation and patient positions. This suggests that the model could potentially be useful in future testing of algorithms to filter and process accelerometer measurements.     

Body fat and skinfold thicknesses: A dimensional analytic approach

Background: Body fat may be estimated from skinfold thickness measurements (Skfs), but current prediction equations are dimensionally inconsistent and do not properly allow for the influence of body size on fat mass.

Aim: To find a dimensionally correct formula relating fat content to Skfs and body size.

Subjects and methods: 285 African children aged 9–11 years, with fat content measured by dual-energy X-ray absorptiometry, were studied. Because least-squares regression parameters can be a misleading guide to true functional relationships, the real data were compared with simulated data sets conforming to a dimensionally correct statistical model.

Results: The data are consistent with functional relationships such that fat mass is proportional to Skf×height². The mean ratio (fat mass)/(Skf×height²) is 6% higher in the girls than in the boys.

Discussion: Appropriately, Skf×height² has the dimensions of fat mass/density. Height² has no obvious physical significance and a more meaningful expression might be ‘height×X', where X corresponds to some measure of body width or girth.

Conclusion: In formulae for predicting fat mass, multiplying Skfs by height² gives better estimates, especially for the tallest and shortest individuals. Fat mass, rather than percentage body fat (%BF), is best taken as the variable initially predicted.