Early experience with computed tomographic angiography in microsurgical reconstruction

Preoperative angiography is frequently used in the planning of microsurgical reconstruction. However, several potentially devastating complications can result from angiography, including arterial occlusion and pseudoaneurysm. Computed tomographic angiography is a relatively new technique that can provide detailed information about vascular anatomy as well as soft and bony tissue without the risks of traditional angiography. In addition, three-dimensional image reconstruction uniquely demonstrates anatomical relationships among blood vessels, bones, and soft tissue. Fourteen computed tomographic angiograms were obtained in 10 patients undergoing microsurgical reconstruction of the head and neck, lower extremity, or upper extremity. The average patient age was 46.9 years (range, 22 to 67 years). Charges related to the computed tomographic procedure were compared with those of conventional preoperative imaging for microsurgical repair. At our institution, the average computed tomographic angiogram charge was 1140 US dollars, whereas the average charge for traditional arteriography was 3900 US dollars. When compared with intraoperative evaluation, computed tomographic angiograms demonstrated clinically relevant surgical anatomy. No complications were noted for the radiographic procedure or after free flap reconstruction. Computed tomographic angiography provides high-resolution, three-dimensional arterial, venous, and soft-tissue imaging without the risks of traditional angiogram and at a lower cost.     

3-D reconstruction of early preimplantation mouse embryo

Method of 3-D reconstruction approaches for early mouse embryo in preimplantation stages was modified. The developed technique is based on application of light microscopy of serial thin sections and well known soft operating. The designed method enabled us 1) to get serial sections of a single mouse embryo; 2) to create an orthogonal system independent on the sample for orientation of virtual sections. The adequacy of 3-DR protocol was checked on reconstruction of air bubbles embedded in epoxy resin as a model of sphere.     

海草形态、生长的种间差异及其相关生长关系

海草是海洋沉水高等植物,属典型的根茎克隆植物.根状茎直径和分株重分别是其个体大小的第一、二表征指标,个体大小是海草重要的种间识别特征.对海草6个形态构件指标和18个生长指标的综合分析表明:果实大小、单株叶面积、分株重具有显著的种特异性;分株发出的时间差、水平根状茎分枝率、叶年产量、分株寿命和垂直茎分枝率是海草种特异性最强的5个生长动态指标,海草生长动态的差异主要体现在克隆生长能力强弱和分株生活史长短上;大海草趋于游击型克隆构型,而小海草则趋于密集型,但小海草Cymodocea nodosa例外;大海草基株水平扩展能力较小海草差.海草个体大小与生长特征的相关生长关系表明:随个体的增大,海草在有机构件生长上表现出两相邻叶、相邻分株、相邻节发出的时间差延长,分株、叶、茎寿命延长的特点;在克隆生长水平上表现出根状茎节间长变短、延伸速率降低,分枝率和根状茎上年产分株数降低,分枝角度变小和间隔子增大的趋势;在克隆片段水平上表现为生理整合性增强;在种群层面则表现出生物量增大和种群密度降低的特点.因此,海草个体大小对其形态、生长特征、克隆构型、种群密度和生产力起到了决定作用.大小海草不同的形态、生长动态和克隆构型特征导致它们的生存策略及生态功能也不同,这一点可能对海草场修复基础理论研究具有一定的指示作用.     

Nuclear medicine: single-photon-emission computed tomographic imaging of the bone

The Scientific Board of the California Medical Association presents the following inventory of items of progress in nuclear medicine. Each item, in the judgment of a panel of knowledgeable physicians, has recently become reasonably firmly established, both as to scientific fact and important clinical significance. The items are presented in simple epitome and an authoritative reference, both to the item itself and to the subject as a whole, is generally given for those who may be unfamiliar with a particular item. The purpose is to assist busy practitioners, students, research workers, or scholars to stay abreast of these items of progress in nuclear medicine that have recently achieved a substantial degree of authoritative acceptance, whether in their own field of special interest or another.The items of progress listed below were selected by the Advisory Panel to the Section on Nuclear Medicine of the California Medical Association, and the summaries were prepared under its direction.     

Cellular development of a nematode: 3-D computer reconstruction of living embryos

Summary Embryos of the free-living soil nematodeCaenorhadditis elegans are capable of developing normally outside the mother; we have monitored this process in isolated embryos by light microscopy and recorded it on video tape. The size and position of each nucleus were entered into a computer at short time intervals from the 2- to 102-cell stages. Models were reconstructed in which nuclei are represented by spheres and assigned different colors and patterns according to lineage membership. Three-dimensional reconstructions aid visualization of the spatial arrangement of nuclei and demonstrate the small degree of positional variance among individuals. The dynamic processes of nuclear growth during the cell cycle, division, migration, and patern formation can be quantitatively analyzed. Our knowledge of the complete embryonic lineage allows the correlation of nuclear behavior with eventual cellular fate.     

Anatomical and computed tomographic studies of the pancreatic tail

The location of the pancreatic tail in the lienorenal ligament and its relationship to the splenic hilus were studied in 32 computed tomography (CT) scannings and in 37 autopsy specimens. We found several anatomical variations in both study groups: the pancreatic tail did not penetrate the lienorenal ligament in 24% of the autopsy specimens and in 37.5% of the CT group. The tail was adjacent to the splenic hilus in 29.7% of the autopsies and in 25% of the CT group. We classified the anatomical variations into 4 categories, three of which could be well demonstrated on CT with satisfactory correlation to the anatomical findings of the autopsy specimens.     

3-D analysis of the Plasmodium falciparum Maurer's clefts using different electron tomographic approaches

The human malaria parasite Plasmodium falciparum exports a large number of proteins into its host erythrocyte to install functions necessary for parasite survival. Important structural components of the export machinery are membrane profiles of parasite origin, termed Maurer's clefts. These profiles span much of the distance between the parasite and the host cell periphery and are believed to deliver P. falciparum-encoded proteins to the erythrocyte plasma membrane. Although discovered more than a century ago, Maurer's clefts remain a mysterious organelle with little information available regarding their origin, their morphology or their precise role in protein trafficking. Here, we evaluated different techniques to prepare samples for electron tomography, including whole cell cryo-preparations, vitreous sections, freeze-substitution and chemical fixation. Our data show that the different approaches tested all have their merits, revealing different aspects of the complex structure of the Maurer's clefts.     

3-D reconstruction of bluetongue virus tubules using cryoelectron microscopy.

Bluetongue virus (BTV) forms tubules in infected mammalian cells. These tubules are virally encoded entities which can be formed with only one protein, NS1. The NS1 protein does not form a part of virus particles, and its function in viral infection is uncertain. Expression of the NS1 gene in insect cells by recombinant baculovirus yields high amounts of NS1 tubules (ca. 50% of cellular proteins) which are morphologically and immunologically similar to authentic BTV NS1 and can be isolated to about 90% purity. The structure of these synthetic NS1 tubules was investigated by cryoelectron microscopy. NS1 tubules are on average 52.3 nm in diameter and up to 100 nm long. The structure of their helical surface lattice has been determined using computer image processing to a resolution of 40 A. The NS1 protein is about 5.3 nm in diameter and forms a dimer-like structure, so that the tubules are composed of helically coiled ribbons of NS1 "dimers," with 21 or 22 dimers per turn. The surface lattice displays P2 symmetry and forms a one-start helix with a pitch of 9.1 nm. The NS1 tubules exist in two slightly different pH-dependent conformational states.     

3-D reconstruction of biological objects using underwater video technique and image processing

This paper describes a 3-D reconstruction method which allows accurate measurements of volume, surface area and other morphometric measurements of three-dimensional biological objects, without removing them from the sea. It represents a novel approach based on multiple views (eight resulted to be sufficient) from underwater video images and a new image processing procedure (MOD3D), whose application has met the basic requirements (i.e. to work on images recorded in turbid waters, with nonuniform lighting, to investigate large areas and in reasonable time, etc.) imposed when operating in the marine environment with simple, easy-to-use and nonprofessional equipment. It is a noninvasive, nondestructive and in the field fast method, thus suitable for sampling also at relevant depth, whose applicability has specifically been set up for a range of growth forms from massive to submassive and irregularly shaped. The accuracy of the method was assessed using models with three levels of 3-D complexity: simple, moderate and complex morphology. A high accuracy of volume measurements made through MOD3D image analysis software was achieved when compared with the laboratory water displacement method, which represents the most accurate method for volume measurement, with an overall mean percent error of about 1.7% (S.D. 2.2%). For all three levels of morphologic complexity, no significant differences (p>0.05) were found. Volume measurements obtained in field based on geometric approximation resulted rough, with significant differences from the MOD3D values (p<0.05). The geometric approximation was lower than MOD3D for simple and moderate morphology, and variable for complex morphology. For all three models, MOD3D values for surface area computation were consistently lower (mean error 13%) than the foil-wrapping values (p<0.05), due to overlap error when foil wrapping. Two applications were made with the bryozoan Pentapora fascialis and the coral Cladocora caespitosa to quantify carbonate standing stock and biomass of these two carbonate framework builders, whose importance has been recently recognised among the temperate sublittoral benthic species. Time required for the 3-D reconstruction method (about 3 h) makes it suitable for routine application particularly for relatively large area investigations, with irregularly shaped objects on rough substrate and several biological objects within the area.     

A statistical approach to computer processing of cryo-electron microscope images: virion classification and 3-D reconstruction

The scattering density of the virus is represented as a truncated weighted sum of orthonormal basis functions in spherical coordinates, where the angular dependence of each basis function has icosahedral symmetry. A statistical model of the image formation process is proposed and the maximum likelihood estimation method computed by an expectation-maximization algorithm is used to estimate the weights in the sum and thereby compute a 3-D reconstruction of the virus particle. If multiple types of virus particle are represented in the boxed images then multiple 3-D reconstructions are computed simultaneously without first requiring that the type of particle shown in each boxed image be determined. Examples of the procedure are described for viruses with known structure: (1). 3-D reconstruction of Flockhouse Virus from experimental images, (2). 3-D reconstruction of the capsid of Nudaurelia Omega Capensis Virus from synthetic images, and (3). 3-D reconstruction of both the capsid and the procapsid of Nudaurelia Omega Capensis Virus from a mixture of unclassified synthetic images.