Progress in the histomorphometry of the microcirculatory system

Following a short review of the limits set to the procedures applied so far to measure quantitative changes in wall tissue of microvessels, a new measuring method is presented. It detect morphological reactions of the microcirculatory system on the grounds of changes in the numerical density of selectively visualized microvessels and their classification according to the external diameter by means of the automatic microscopic image analysing system QUANTIMET. Influences of structurally based and/or postmortal changes of the lumen wideness on the measurement are excluded by the automatic subtraction of the lumen area.     

Use of the television analysing system in the studies on microcirculation]

In the experiments on anesthetized rats the television analysing system (LEITZ-TAS) was used for evaluation of quantitative structure-functional characteristics of microcirculation under intravital conditions and the development of microvessel network, for measuring geometric parameters of microvessels and blood flow change in them, as well as to define the degree and spreading of the disturbances in the vessel wall permeability.     

A general purpose computerized display and analysis system for image processing in nuclear medicine.

In this work a general purpose image processor is described, which takes into account the special features and the various requirements for analysing images in nuclear medicine. A new approach for system structure involving encoding and representing medical images is given. This encoder, which is part of the image processor, is efficient especially for long-term storage and for certain pattern recognition in medical imaging. In this processor a statistical package is incorporated for collecting medical statistics using the acquired patient data. This information is used together with the encoder for an automated diagnostic system.     

Microvessel diameter estimation: error bias correction of serial measurements

The assessment of vessel patency can be substantially improved by serial microvessel diameter measurements taken successively along an extensive length of the vessel. It is possible to avoid making the a priori assumptions about the existence or location of local constriction sites implicit in single diameter measurements. The problem then becomes one of making sense of tens or hundreds of measurements for each vessel. Equivalent diameter is defined here as as the diameter of a uniform circular cylinder of the same length as the original vessel, and having the same total resistance. Direct computation of the equivalent diameter, without taking measurement errors into account, leads to an underestimation of the true equivalent diameter even if the individual diameter measurements were not biased. We have developed a method for effectively eliminating this bias. It has been applied to serial microvessel diameter measurements of the guinea pig cochlea, automatically measured using an image analysis system. In this report, the results were developed for diameter estimates with an approximate gaussian distribution; however the method is readily extended to other error distributions. Convergence of the bias compensation was rapid. Use of the new method is advisable with as few as three diameter estimates per vessel.     

Quantification of angiogenesis by a computerized image analysis system in renal cell carcinoma

OBJECTIVE: To ascertain whether tumor angiogenesis quantitated by a computerized image analysis system correlates with clinical outcome in renal cell carcinoma. STUDY DESIGN: Microvessels were immunohistochemically labeled with antibodies to CD34 in sections from 62 cases of renal cell carcinoma. Computerized image analysis was used to evaluate the mean microvessel count (MMC) and mean percentage microvessel area (MPMA). RESULTS: MMC ranged from 19.3 to 315.0, while MPMA was 0.6-17.9%. There was a highly significant correlation between MMC and MPMA (r = .867, P < .01). Although MMC and MPMA decreased with increasing nuclear grade and TNM stage, this difference failed to achieve statistical significance. No statistically significant differences in survival were found for MMC or MPMA. CONCLUSION: Our results indicate that computerized image analysis can evaluate accurately tumor angiogenesis, but tumor angiogenesis in renal cell carcinoma does not provide significant prognostic information in renal cell carcinoma.     

Numerical simulation of blood flow in the left ventricle and aortic sinus using magnetic resonance imaging and computational fluid dynamics

Understanding cardiac blood flow patterns has many applications in analysing haemodynamics and for the clinical assessment of heart function. In this study, numerical simulations of blood flow in a patient-specific anatomical model of the left ventricle (LV) and the aortic sinus are presented. The realistic 3D geometry of both LV and aortic sinus is extracted from the processing of magnetic resonance imaging (MRI). Furthermore, motion of inner walls of LV and aortic sinus is obtained from cine-MR image analysis and is used as a constraint to a numerical computational fluid dynamics (CFD) model based on the moving boundary approach. Arbitrary Lagrangian–Eulerian finite element method formulation is used for the numerical solution of the transient dynamic equations of the fluid domain. Simulation results include detailed flow characteristics such as velocity, pressure and wall shear stress for the whole domain. The aortic outflow is compared with data obtained by phase-contrast MRI. Good agreement was found between simulation results and these measurements.     

The fluid shear stress distribution on the membrane of leukocytes in the microcirculation

Recent in-vivo and in-vitro evidence indicates that fluid shear stress on the membrane of leukocytes has a powerful control over several aspects of their cell function. This evidence raises a question about the magnitude of the fluid shear stress on leukocytes in the circulation. The flow of plasma on the surface of a leukocyte at a very low Reynolds number is governed by the Stokes equation for the motion of a Newtonian fluid. We numerically estimated the distribution of fluid shear stress on a leukocyte membrane in a microvessel for the cases when the leukocyte is freely suspended, as well as rolling along or attached to a microvessel wall. The results indicate that the fluid shear stress distribution on the leukocyte membrane is nonuniform with a sharp increase when the leukocyte makes membrane attachment to the microvessel wall. In a microvessel (10 microns diameter), the fluid shear stress on the membrane of a freely suspended leukocyte (8 microns diameter) is estimated to be several times larger than the wall shear stress exerted by the undisturbed Poiseuille flow, and increases on an adherent leukocyte up to ten times. High temporal stress gradients are present in freely suspended leukocytes in shear flow due to cell rotation, which are proportional to the local shear rate. In comparison, the temporal stress gradients are reduced on the membrane of leukocytes that are rolling or firmly adhered to the endothelium. High temporal gradients of shear stress are also present on the endothelial wall. At a plasma viscosity of 1 cPoise, the peak shear stresses for suspended and adherent leukocytes are of the order of 10 dyn/cm2 and 100 dyn/cm2, respectively.     

基于虚拟仪器技术的血管壁动态信息无创检测与辅助诊断系统

为了在体外无损地实现对血管壁动态信息、心电和心音信号等医学信息多参数的综合同步检测以及分析和处理,利用虚拟仪器技术设计了血管壁动态信息多参数的无创检测辅助诊断系统．该系统硬件平台由信号输入模块、信号调理模块以及采集卡等三大模块组成。软件系统由开发虚拟仪器的流行软件LabVIEW编写,实现了数据的采集、实时显示、分析处理和存储等。初步的临床检测结果证实了本无创检测系统的可行性和临床应用的前景,为功能性无创辅助诊断与血管壁弹性（硬化）程度有关的血管疾病提供了一种新的方法。     

Non-contacting electrode system for the measurement of strain generated potentials in bone

Current methods employing contact electrodes for the measurement of the electromechanical properties of bone produce errors in the measurement due to the effects of polarization at the bone-electrode interface, and the flow of electric charges in the bone measuring circuit. In addition, signal artefacts may result from the movement of an electrode in contact with a specimen undergoing mechanical deformation. The principles for a non-contacting method, based on charge induction on a conductive plate placed in the field of a charged body (bone), and the resulting non-contacting electrode system are presented in this paper. The new electrode enabled measurement of strain generated potentials (SGP) in bone with minimal effect from the measuring circuit and provided new results previously masked by contacting measurement methods. Furthermore, the new electrode is a potential tool for further investigation of the in vitro electromechanical behaviour of bone, particularly in partially hydrated specimens and in vivo, thereby avoiding invasive methods or use of ionizing radiation.     

Determination of the filamentous cyanobacteria Planktothrix rubescens in environmental water samples using an image processing system

Cyanobacteria occur in surface waters worldwide. Many of these produce peptides and/or alkaloids, which can present a risk for animal and human health. Effective risk assessment and management requires continuous and precise observation and quantification of cyanobacterial cell densities. In this respect, quantification of filamentous Planktothrix species is problematic. The aim of this study was to develop an automated system to count filamentous Planktothrix rubescens using image processing. Furthermore, this study aimed to assess optimum sample volumes and filament density for measurement precision and to validate image processing measurement of P. rubescens for an effective risk assessment.Three environmental samples and one cultured sample of P. rubescens were collected by filtration onto nitrocellulose filters. Filament lengths were determined using fluorescence microscopy combined with an image processor. Cell density could be calculated from the resulting images. Cyanobacteria could easily be discriminated from algae via their fluorescence properties. The results were found to be independent of the mode of image acquisition. The precision of total filament length determination was dependent on the total filament length on the filter, i.e. analyses of highest precision could be expected for filters containing 2000–20,000 μm filaments per mm². When using suitable filtration volumes, the detection limits of the described method are sufficient for an effective risk assessment. To summarise, this procedure is a fast, easy and accurate method to determine cell densities of filamentous P. rubescens in water samples without costly and tedious manual handling.     

Evaluation of image analysis and laser granulometry for microbial cell sizing

A direct cell size measurement technique and an image analysis based sizing method were developed. The former consisted of a manual size measurement of the two-dimensional cell images on a video screen, with automatic data recording. This method was chosen as the reference. The latter, a semiautomatic method took advantage of a commercial computer program designed for image processing and particle morphology analysis. It gave average and median size values which were compatible with the manual method. However, the performance of these time consuming methods is limited. Hence, the laser granulometry technique, intrinsically far more powerful while capable of analysing millions of sample objects in a short time delay, was applied. The comparison revealed that this method gives too low size values, particularly in disagreement with the known dimensions of the bacterial (Zymomonas mobilis) cells. A size correction method was developed to realign the granulometry results ofZ. mobilis cell samples with those of the direct manual measurement method.     

Optical aspect of deformation analysis in the bone-denture complex

The aim of this study was to register and measure any deformation of mandible models under load. The method for full field measurement of strain is done by using the ARAMIS three-dimensional image correlation system. The system uses two digital cameras that provide a synchronized stereo view of the specimen and the results show the complete strain field during the tests. The biggest deformation values were just under the working force of the biggest intensity 500 N, and for the region of the lower second premolar the deformation is 625 microm. The following study is presented that highlight the use of stereometric measuring system for modern research. It is shown that this measuring methodology can capture the trends of the experiments.     

Segmentation of moving images by the human visual system

 New segments appearing in an image sequence or spontaneously accelerated segments are band limited by the visual system due to a nonperfect tracking of these segments by eye movements. In spite of this band limitation and acceleration of segments, a coarse segmentation (initial segmentation phase) can be performed by the visual system. This is interesting for the development of purely automatic segmentation algorithms for multimedia applications. In this paper the segmentation of the visual system is modelled and used in an automatic coarse initial segmentation. A suitable model for motion processing based on a spectral representation is presented and applied to the segmentation of synthetic and real image sequences with band limited and accelerated moving foreground and background segments. Received: 1 August 1995/Accepted in revised form: 25 February 1997     

Vascular response of the rabbit bladder to chronic partial outlet obstruction

Partial outlet obstruction of the rabbit urinary bladder results, initially, in a rapid increase in bladder mass and remodeling of the bladder wall. Previously, it was shown that this response was characterized by serosal growth (thickening) which was apparent after 1 day of obstruction, before any visible vascularization was observed. After 1 week of obstruction, significant microvessel formation was seen in the transition region between the detrusor smooth muscle and the thickening serosa; after 2 weeks the entire serosa was vascularized.In this study we investigated the effect of chronic (4 week) partial outlet obstruction on microvessel density and distribution in the bladder wall immunohistochemically using CD31 as a marker for vascular endothelium. Transverse sections of bladder wall were examined after 4 weeks of no surgery, sham surgery or partial obstruction.The microvessel density of the obstructed rabbit bladder mucosa and detrusor smooth muscle increased relative to augmentation of these compartments while new vessels appeared in the thickening serosa. Although vessel density did not change with obstruction a significant shift in mean vessel circumference to the left occurred indicating a significant increase in the number of microvessels and small vessels consistent with angiogenesis.     

Quantitative electronic analysis of chromosome autoradiographs using a television image analysing computer

A quantitative method for analysis of chromosome autoradiographs, using a TV image analysing computer (Leitz Classimat) is described. The principle of the method is based on an integrated measurement of silver grain areas, selected by grey value discrimination. The areas are shown to be representative for the amount of radioactive substance present, and are suitable for comparison of different grain densities over chromosomes.     

Cesar: A computer supported measurement system for the enhancement of diagnostics and quality in cytology

In the following presentation, the concept of the CESAR Cytology system (CE11 Screen and Analysing Routine system) is introduced, which unlike conventional systems also comprehensively integrates human empiric knowledge in the evaluation and interpretation of the measurement results. For this purpose CESAR is especially equipped with an object-oriented data base. Due to its special structure graphical presentations of the measurement or classification results (histograms, scatterplots) can be used as directories of a cell image data base. In this way the numerical results can be ‘translated’ into cell images with a similar content of information, but which are far better suited to be compared with the empirical knowledge of the human brain.     

Microperfusion Technique to Investigate Regulation of Microvessel Permeability in Rat Mesentery

Experiments to measure the permeability properties of individually perfused microvessels provide a bridge between investigation of molecular and cellular mechanisms regulating vascular permeability in cultured endothelial cell monolayers and the functional exchange properties of whole microvascular beds. A method to cannulate and perfuse venular microvessels of rat mesentery and measure the hydraulic conductivity of the microvessel wall is described. The main equipment needed includes an intravital microscope with a large modified stage that supports micromanipulators to position three different microtools: (1) a beveled glass micropipette to cannulate and perfuse the microvessel; (2) a glass micro-occluder to transiently block perfusion and enable measurement of transvascular water flow movement at a measured hydrostatic pressure, and (3) a blunt glass rod to stabilize the mesenteric tissue at the site of cannulation. The modified Landis micro-occlusion technique uses red cells suspended in the artificial perfusate as markers of transvascular fluid movement, and also enables repeated measurements of these flows as experimental conditions are changed and hydrostatic and colloid osmotic pressure difference across the microvessels are carefully controlled. Measurements of hydraulic conductivity first using a control perfusate, then after re-cannulation of the same microvessel with the test perfusates enable paired comparisons of the microvessel response under these well-controlled conditions. Attempts to extend the method to microvessels in the mesentery of mice with genetic modifications expected to modify vascular permeability were severely limited because of the absence of long straight and unbranched microvessels in the mouse mesentery, but the recent availability of the rats with similar genetic modifications using the CRISPR/Cas9 technology is expected to open new areas of investigation where the methods described herein can be applied.     

Quantifying whole bladder biomechanics using the novel pentaplanar reflected image macroscopy system

Optimal bladder compliance is essential to urinary bladder storage and voiding functions. Calculated as the change in filling volume per change in pressure, bladder compliance is used clinically to characterize changes in bladder wall biomechanical properties that associate with lower urinary tract dysfunction. But because this method calculates compliance without regard to wall structure or wall volume, it gives little insight into the mechanical properties of the bladder wall during filling. Thus, we developed Pentaplanar Reflected Image Macroscopy (PRIM): a novel ex vivo imaging method to accurately calculate bladder wall stress and stretch in real time during bladder filling. The PRIM system simultaneously records intravesical pressure, infused volume, and an image of the bladder in five distinct visual planes. Wall thickness and volume were then measured and used to calculate stress and stretch during filling. As predicted, wall stress was nonlinear; only when intravesical pressure exceeded ~ 15 mmHg did bladder wall stress rapidly increase with respect to stretch. This method of calculating compliance as stress vs stretch also showed that the mechanical properties of the bladder wall remain similar in bladders of varying capacity. This study demonstrates how wall tension, stress and stretch can be measured, quantified, and used to accurately define bladder wall biomechanics in terms of actual material properties and not pressure/volume changes. This method is especially useful for determining how changes in bladder biomechanics are altered in pathologies where profound bladder wall remodeling occurs, such as diabetes and spinal cord injury.

     

Investigations into the application of a process for the determination of microbial activity in biofilms

The formation of biofilms in a waste paper medium was studied in a pilot plant by analysing the redox potential in the biofilm. Miniaturised redox electrodes were applied at the reactor wall/biofilm phase boundary. With this measurement set-up, it was possible to demonstrate the effectiveness of biocides and thus to avoid under- and over-doses with these agents. The redox signals measured were correlated with reference methods, such as colony-forming units and dehydrogenase activity.     

Method to classify xylem cell types using cross sectionsof 1-year-old branches in Mediterranean woody species

Measurements of anatomical parameters of wood are of great interest both for eco-physiological purposes and for technological applications. The aim of this paper is to describe a new method for classifying and measuring cell lumen of xylem, analysing cross sections under the light microscope. The proposed method is based on the application of digital image analysis on images of the cross sections of xylem in combination with graphical and statistical methods. The methodology was tested on 1-year-old branches of several woody species, both trees and shrubs, occurring in a Mediterranean natural ecosystem in southern Italy. The development of the procedure was based on statistical comparison between data collected according to four procedures: (a) manual identification and measurement of lumen diameter of conduits on longitudinal sections; (b) manual identification and measurement of lumen diameter of conduits on cross sections; (c) manual identification and measurement of lumen area of conduits on cross sections; and (d) automatic measurement of lumen area of conduits on cross sections. The influence of image resolution and that of the position of the selected area on cell classification and measurements were ascertained. The proposed method was proved to be specific to woody structures and allowed the construction of a model-graph that is species-specific. Interpretation of the model-graphs allows classification and hence measurement of identified cells.