Physiological effects of dynamic work on a bicycle ergometer combined with different types of static contraction

Summary The effects on heart rate, oxygen uptake, and pulmonary ventilation of muscular exercises, including both dynamic contractions, either simple or combined, were studied in 4 male subjects, aged 21 to 23 years. The dynamic work consisted in cycling on an ergometric bicycle at three power levels: 40, 80, and 100 W. The static work consisted in pushing against, pulling and holding with the arms a 6, 9, 12, or 18 kg load. The physiological effects are expressed as cardiac cost (HR), oxygen cost (VO₂) and ventilation cost (V). The physiological cost of the combined work increases according to the cycling power and to the isometric load developed. A statistical analysis shows that the costs of combined work are not different from the sum of the costs of the static and dynamic contractions measured separately. Thus, the physiological responses to the combinations investigated are of an additive type.     

Impact of Breast Density on Computer-Aided Detection in Full-Field Digital Mammography

The goal of this study was to evaluate the performance of a computer-aided detection (CAD) system in full-field digital mammography (Senographe 2000D, General Electric, Buc, France) in finding out carcinomas depending on the parenchymal density. A total of 226 mediolateral oblique (MLO) and 186 craniocaudal (CC) mammographic views of histologically proven cancers were retrospectively evaluated with a digital CAD system (ImageChecker V2.3 R2 Technology, Los Altos, CA, USA). Malignant tumors were detected correctly by CAD in MLO view in 84.85% in breasts with parenchymal tissue density of the American College of Radiology (ACR) type 1, in 70.33% of the ACR type 2, in 68.12% of the ACR type 3, and in 69.70% of the ACR type 4. For the CC view, similar results were found according to the ACR types. Using the chi-square and McNemar tests, there was no statistical significance. However, a trend of better detection could be seen with decreasing ACR type. In conclusion, there seems to be a tendency for breast tissue density to affect the detection rate of breast cancer when using the CAD system.     

Design and application of sensor for recording sounds over human eye and nose

The recording of sounds over the oribt of the eye has been found to be useful in the detection of intracranial aneurysms. A hydrophone for auscultation over the eye has been developed and is tested under controlled conditions. The tests consist of measurement over the eyes in three healthy volunteers at rest, during voluntary breathing, during eyeball movements and during sustained orbicular muscular contractions. Furthermore, measurements are performed at the side of the nose. Major features of the hydrophonic transducer are high sensitivity to physiological sounds and a high degree of insensitivity to environmental sounds propagated through the air. It can be concluded that the hydrophone may be useful for the early detection of intracranial aneurysms and also for apnoea detection.     

Pyrosequencing for detection of mutations in the connexin 26 (GJB2) and mitochondrial 12S RNA (MTRNR1) genes associated with hereditary hearing loss

Hereditary hearing loss (HHL) is one of the most common congenital disorders and is highly heterogeneous. Mutations in the connexin 26 (CX26) gene (GJB2) account for about 20% of all cases of childhood deafness, and approach 50% in documented recessive cases of non-syndromic hearing loss. In addition, a single mitochondrial DNA mutation, mt1555A>G, in the 12S rRNA gene (MTRNR1), is associated with familial cases of progressive deafness. Effective screening of populations for HHL necessitates rapid assessment of several of these potential mutation sites. Pyrosequencing links a DNA synthesis protocol for determining sequence to an enzyme cascade that generates light whenever pyrophosphate is released during primer strand elongation. We assessed the ability of Pyrosequencing to detect common mutations causing HHL. Detection of the most common CX26 mutations in individuals of Caucasian (35delG), Ashkenazi (167delT), and Asian (235delC, V37I) descent was confirmed by Pyrosequencing. A total of 41 different mutations in the CX26 gene and the mitochondrial mt1555A>G mutation were confirmed. Genotyping of up to six different adjacent mutations was achieved, including simultaneous detection of 35delG and 167delT. Accurate and reproducible results were achieved taking advantage of assay flexibility and experimental conditions easily optimized for a high degree of standardization and cost-effectiveness. The standardized sample preparation steps, including target amplification by PCR and preparation of single-stranded template combined with automated sequence reaction and automated genotype scoring, positions this approach as a potentially high throughput platform for SNP/mutation genotyping in a clinical laboratory setting. .     

Detection of DNA from infectious laryngotracheitis virus by colourimetric analyses of polymerase chain reactions

A combination of the polymerase chain reaction and a novel ELISA-type DNA colourimetric assay (developed from studies with a retrovirus from man) was used in a preliminary study to detect DNA from avian infectious laryngotracheitis virus. The method is sensitive, specific and easy to perform. Since it can be readily adapted for the detection of DNA from other sources it could be useful for the identification of a variety of pathogens from other species of veterinary importance.     

“Smart” Materials for Biosensing Devices: Cell-Mimicking Supramolecular Assemblies and Colorimetric Detection of Pathogenic Agents

Mimicking cell membrane and the biomolecular recognition associated with membranes represents a great technical challenge, yet it has opened doors to innovative diagnostic and therapeutic methods. Our work has focused on design and synthesis of a class of smart materials exploiting biological principals for use in biosensors: these materials are functional polymeric assemblies that mimic the cell membrane and conveniently report the presence of pathogens with a color change. Biologically active cell membrane components are incorporated into conjugated polymers with desirable optical properties and the binding of the target molecules onto the material triggers conformational and electronic shifts that are reflected in a chromatic change (a so-called biochromic shift) that is conveniently observed and recorded. Langmuir–Blodgett thin films and vesicle bilayers provide ideal configurations for precise delivery of the biological binding entity to the sensing interface, and for control of molecular orientation for effective biomolecular interaction. Polydiacetylenic membrane-mimicking materials containing cell surface receptor gangliosides and sialic acid residues, respectively were formulated into these architectures and used for colorimetric detection of bacterial toxins and influenza virus. One advantage of these biochromic conjugated polymer (BCP) sensors is that their molecular recognition and signal transduction functionalities are resident in a single functional unit, making them amenable to convenient microfabrication and use.     

Real-time automatic extraction of lumen region and boundary from endoscopic images

A new approach to the automatic extraction of the lumen region and its boundary for gastrointestinal (GI) endoscopic images is presented. First, a quasi region of interest, the darker regions of the image, is segmented using a region splitting scheme termed progressive thresholding. The centre of mass of this segmented region acts as a seed for further processing. Then the lumen region is obtained using a region growing technique called the integrated neighbourhood search (INS). A new quad structure based technique is introduced to enhance the INS speed significantly. A back projection algorithm is suggested to optimise the search for pixels belonging to the lumen region and boundary. A boundary-thinning algorithm is also proposed to remove the redundant pixels from the lumen boundary and to generate a connected single pixel width boundary. The proposed approach does not need a priori knowledge about the image characteristics. The experimental results indicate that the proposed technique enhances the speed of conventional INS by 45.5% to 28.6% based on the lumen size varying from 22,709 pixels to 4947 pixels. The main advantage of the proposed technique is its high-speed response that facilitates real-time analysis of endoscopic images.     

Experimental rat model for therapeutic retinal pigment epithelium transplantation—unequivocal microscopic identification of human donor cells by in situ hybridisation of human-specific Alu sequences

Transplantation of retinal pigment epithelial (RPE) cells is discussed as a possible therapeutic approach for retinal degeneration. Xenogeneic transplantation of human RPE cells in animal models has been studied extensively. Various methods have been used to identify the graft cells, but these methods interfere with cell behaviour so that the monitored physiological post-transplantation course may be influenced. In the present study, we applied a method for an unequivocal identification of the graft cells without interfering cell metabolism or behaviour using in situ hybridisation (ISH) of human specific Alu sequences. Visualisation of the strong extended nuclear signal of Alu sequences was much easier than that of the small nuclear signals of donor-specific sex chromosome probes. With Alu probe, even single graft cells can be identified and their development can be observed in short-term and long-term studies. With this procedure, we could prove that donor cells were injected correctly into the subretinal space by a special injection technique that we developed previously. In combination with immunohistochemistry, donor cells could be clearly discriminated from macrophages, which contained phagocytosed donor cell fragments. Application of these ISH methods for species-specific identification was valuable for follow-up-studies of RPE transplantation.     

Rapid molecular cytogenetic analysis of X-chromosomal microdeletions: Fluorescence in situ hybridization (FISH) for complex glycerol kinase deficiency

Diagnosis of X-chromosomal microdeletions has relied upon the traditional methods of Southern blotting and DNA amplification, with carrier identification requiring timeconsuming and unreliable dosage calculations. In this report, we describe rapid molecular cytogenetic identification of deleted DNA in affected males with the Xp21 contiguous gene syndrome (complex glycerol kinase deficiency, CGKD) and female carriers for this disorder. CGKD deletions involve the genes for glycerol kinase, Duchenne muscular dystrophy, and/or adrenal hypoplasia congenita. We report an improved method for diagnosis of deletions in individuals with CGKD and for identification of female carriers within their families, using fluorescence in situ hybridization (FISH) with a cosmid marker (cosmid 35) within the glycerol kinase gene. When used in combination with an Xq control probe, affected males demonstrate a single signal from the control probe, while female carriers demonstrate a normal chromosome with two signals, as well as a deleted chromosome with a single signal from the control probe. FISH analysis for CGKD provides the advantages of speed and accuracy for evaluation of submicroscopic X-chromosomal deletions, particularly in identification of female carriers. In addition to improving carrier evaluation, FISH will make prenatal diagnosis of CGKD more readily available. © 1995 Wiley-Liss, Inc.     

Detection and analysis of gastrointestinal sounds in normal and small bowel obstructed rats

This study is aimed at detecting gastrointestinal sounds (GIS) and correlating their characteristics with gastrointestinal (GI) conditions. The central hypotheses are that GIS generation depends on the motility patterns and the mechanical properties of the gut, and that changes in those result in measurable differences in GIS. An animal model which included both healthy rats and those with small bowel obstruction (SBO) was developed. The acoustic bursts, of GIS were detected by amplitude thresholding the signal envelope. Three methods of envelope estimation were proposed and evaluated. Envelope estimation using a Hilbert transform was found to produce the best results in the current application. The duration and dominant frequency of each detected GIS event was estimated and clear differences between healthy and diseased rats were discovered. In the control state, GIS events were found to consistently be of relatively short duration (3–65ms). Although the majority of events in the SBO state had similar short duration, infrequent longer events were also detected and appeared to be pathognomonic. Long duration events (>100 ms) occurred in each of seven obstructed, but in none of 14 non-obstructed, cases (p<0.001). It is concluded that GIS analysis may prove useful in the non-invasive, rapid, and accurate diagnosis of SBO.