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PubMed2001

Symmetry measures of vestibular evoked myogenic potentials using objective detection criteria.

Vestibular evoked myogenic potentials (VEMP) has been put forward as a test to evaluate the symmetry of saccular function. In the present study, the symmetry of VEMP was evaluated in 23 healthy subjects using automatic analysis. In response to binaural clicks with a stimulus repetition rate of 4/s all subjects revealed significant VEMP on both sides. The ipsilateral response to monaural clicks was similar to the response to binaural clicks. Although there were large interindividual variations in amplitude, there were only small variations in latency. VEMP measurements were also assessed using different stimulus rates. At the higher stimulus rates there was a decrease in the VEMP amplitude but there were only small changes in the latency. These findings might suggest that amplitude measures are more likely than latency measures to reveal small vestibular lesions.

Adult↗
PubMed1999

Measures of the binaural interaction component in human auditory brainstem response using objective detection criteria.

The occurrence of binaural interaction in humans has been demonstrated using auditory brainstem response (ABR). A distinctly binaural potential, beta, is derived by subtracting the ABR recording evoked by binaural clicks from the monaural aggregate, i.e., the sum of the two corresponding ABR recordings evoked by monaural clicks. However, few clinical data are available, possibly because the beta-wave is considered an elusive response due to a low signal-to-noise-ratio. In the present study, beta-wave latency, amplitude and area were evaluated for 10 subjects with normal hearing using automatic analysis and averaging based on a large number of stimulations. The efficacy of the beta-wave measures was assessed using different stimulus rates, as binaural interaction is known to decrease with increasing stimulus rate. It was found that the beta-wave given by automatic analysis demonstrated known characteristics of binaural interaction in human ABR, i.e. the absence of binaural interaction during wave III, significant binaural interaction during wave V and a significant decrease in binaural interaction when the stimulus rate was increased. These findings suggest that a beta-wave in the binaural difference waveform can be detected and quantified using automatic analysis, thus it is suitable for clinical studies, at least for patients with normal hearing thresholds.

Adult↗
PubMed2005

Echolocation characteristics of free-swimming bottlenose dolphins during object detection and identification.

A biosonar measurement tool (BMT) was created to investigate dolphin echolocation search strategies by recording echolocation clicks, returning echoes, and three-dimensional angular motion, velocity, and depth of free-swimming dolphins performing open-water target detections. Trial start and stop times, locations determined from a differential global positioning system (DGPS), and BMT motion and acoustic data were used to produce spatial and acoustic representations of the searches. Two dolphins (LUT, FLP) searched for targets lying on the seafloor of a bay environment while carrying the BMT. LUT searched rapidly (< 10 s), produced few clicks, and varied click-peak frequency (20-120 kHz); FLP searched relatively slowly (tens of seconds) and produced many hundreds of clicks with stereotypical frequency-dependent energy distributions dominating from 30-60 kHz. Dolphins amplified target echo returns by either increasing the click source level or reducing distance to the target but without reducing source level. The distribution of echolocation click-peak frequencies suggested a bias in the dominant frequency components of clicks, possibly due to mechanical constraints of the click generator. Prior training and hearing loss accommodation potentially explain differences in the search strategies of the two dolphins.

Animal Communication↗
PubMed1978

Objective detection of reversible deficiencies in glaucoma by means of BECP.

The dynamic properties of the VECP trigger mechanism are used as a functional test for the glaucomatous eye. A light-emitting diode is used as stimulator. The test was performed under the condition of the functional isolation of the red colour mechanism (by means of selective colour adaptation technique). In any case, a delayed rise of stimulus luminance causes a delay of the VECP. This delay increases in patients with glaucoma. After a successful glaucoma operation the VECP delay diminishes again.

Color Perception Tests↗
PubMed1970

[Objective detection of the effects of radiotherapy on female patients with tumors].

The effect of therapeutical irradiation of uterus carcinoma and corpus carcinoma was measured by the intake of bromine and iodine in methanolic serum extract. It was done by electrometric titration. The irradiation causes a decrease of the level of unsaturated fatty acids and an individually different increase of the redox value.

Adenocarcinoma↗
PubMed1984

Alkaline reflux esophagitis in gastroresected patients. Objective detection with a simple isotope method.

The incidence and severity of alkaline reflux esophagitis occurring in 1129 gastroresected patients were evaluated. As far as the incidence of esophagitis are concerned, no significant difference was found after Billroth I or Billroth II type resection. Severe esophagitis developed in 62.6 per cent of patients with total gastrectomy, but never occurred when a long limb Roux-en-Y anastomosis was also performed. The majority of esophagitis was recognized within the first year after resection, so it might be supposed that not only operative procedure itself but the postoperative care period might be responsible for the development of esophagitis. It can be avoided and treated by Roux-en-Y anastomosis. Scintigraphy is a simple rapid method in the detection of gastroesophageal reflux, thus patients can be selected by it for further invasive investigation.

Duodenogastric Reflux↗
PubMed2000

Detection of object motion by a fly neuron during simulated flight.

Object detection on the basis of relative motion was investigated in the fly at the neuronal level. A representative of the figure detection cells (FD-cells), the FD1b-cell, was characterized with respect to its responses to optic flow which simulated the presence of an object during translatory flight. The figure detection cells reside in the fly's third visual neuropil and are believed to play a central role in mediating object-directed turning behaviour. The dynamical response properties as well as the mean response amplitudes of the FD1b-cell depend on the temporal frequency of object motion and on the presence or absence of background motion. The responses of the FD1b-cell to object motion during simulated translatory flight were compared to behavioural responses of the fly as obtained with identical stimuli in a previous study. The behavioural responses could only partly be explained on the basis of the FD1b-cell's responses. Further processing between the third visual neuropil and the final motor output has to be assumed which involves (1) facilitation of the object-induced responses during translatory background motion at moderate temporal frequencies, and (2) inhibition of the object-induced turning responses during translatory background motion at high temporal frequencies.

Animals↗
PubMed2000

Automatic detection of foreign objects in computed radiography.

This paper presents an effective two-step scheme for automatic object detection in computed radiography (CR) images. First, various structure elements of the morphological filters, designed by incorporating available morphological features of the objects of interest including their sizes and rough shape descriptions, are used to effectively distinguish the foreign object candidates from the complex background structures. Second, since the boundaries of the objects are the key features in reflecting object characteristics, active contour models are employed to accurately outline the morphological shapes of the suspicious foreign objects to further reduce the rate of false alarms. The actual detection scheme is accomplished by jointly using these two steps. The proposed methods are tested with a database of 50 hand-wrist computed radiographic images containing various types of foreign objects. Our experimental results demonstrate that the combined use of morphological filters and active contour models can provide an effective automatic detection of foreign objects in CR images achieving good sensitivity and specificity, and the accurate descriptions of the object morphological characteristics.

Algorithms↗
PubMed2005

[Study on the internal control on polymerase chain reaction in Yersinia pestis detection].

OBJECTIVE: For the detection of Yersinia pestis by polymerase chain reaction (PCR), internal control (IC) is required in order to prevent false negative results that might be caused by PCR inhibitors. METHODS: F1 antigen was amplified by PCR with primer F1 and the PCR product of primer F1 were cloned with TOPO TA cloning Kit. The plasmid of positive clone was then digested with HpaI. The digested plasmid and the PCR products of 16S rRNA were ligated with T(4) DNA ligase before the ligated products were transformed. Isolate plasmid DNA on positive clone and its concentration were measured. Plasmid DNA on different concentration by PCR amplification with primer F1 was analyzed and the standard concentration of IC was determined. RESULTS: Constructing an IC by inserting a 16S rRNA amplicon to the original target DNA between the two primer F1 sites, the size was longer than the target DNA. The standard concentration of IC was determined. CONCLUSION: An optimal IC concentration to increase the reliability of the PCR assays might be used to prevent false negative results and appeared to be useful for detection of Yersinia pestis.

Bacterial Proteins↗
PubMed1992

Orthopteran DCMD neuron: a reevaluation of responses to moving objects. II. Critical cues for detecting approaching objects.

1. We examine the critical image cues that are used by the locust visual system for the descending contralateral motion detector (DCMD) neuron to distinguish approaching from receding objects. Images were controlled by computer and presented on an electrostatic monitor. 2. Changes in overall luminance elicited much smaller and briefer responses from the DCMD than objects that appeared to approach the eye. Although a decrease in overall luminance might boost the response to an approaching dark object, movement of edges of the image is more important. 3. When two pairs of lines, in a cross-hairs configuration, were moved apart and then together again, the DCMD showed no preference for divergence compared with convergence of edges. A directional response was obtained by either making the lines increase in extent during divergence and decrease in extent during convergence; or by continually increasing the velocity of line movement during divergence and decreasing velocity during convergence. 4. The DCMD consistently gave a larger response to growing than to shrinking solid rectangular images. An increase compared with a decrease in the extent of edge in an image is, therefore, an important cue for the directionality of the response. For single moving edges of fixed extent, the neuron gave the largest response to edges that subtended 15 degrees at the eye. 5. The DCMD was very sensitive to the amount by which an edge traveled between frames on the display screen, with the largest responses generated by 2.5 degrees of travel. This implies that the neurons in the optic lobe that drive this movement-detecting system have receptive fields of about the same extent as a single ommatidium. 6. For edges moving up to 250 degree/s, the excitation of the DCMD increases with velocity. The response to an edge moving at a constant velocity adapts rapidly, in a manner that depends on velocity. Movement over one part of the retina can adapt the subsequent response to movement over another part of the retina. 7. For the DCMD to track and continue to respond to the image of an approaching object, the edges of the image must continually increase in velocity. This is the second important stimulus cue. 8. Edges of opposite contrasts (light-dark compared with dark-light) are processed in separate pathways that inhibit each other. This would contribute to the reduction of responses to wide-field movements.

Adaptation, Physiological↗
PubMed2005

Cardiovascular risk factors in primary care: methods and baseline prevalence rates--the DETECT program.

OBJECTIVES: DETECT is an epidemiological study in primary care to examine (a) the prevalence rates and comorbidity of diabetes mellitus, hypertension, hyperlipidaemia and coronary heart disease (CHD), and associated conditions; (b) the frequency of behavioural and clinical risk factors for onset and progression; (c) the 12-month course and outcome; and (d) the met and unmet needs for these patients. METHODS: Three-stage, cross-sectional clinical-epidemiological study with a prospective-longitudinal component in a nationally representative sample of N = 3795 primary care settings [response rate (RR): 60.2%] and N = 55518 patients (RR: 95.5%). Patients completed a standardized assessment, including questionnaires for patients and the physician and diagnostic screening measures (i.e. blood pressure, heart rate, body mass index and waist circumference assessments). A subsample of patients (N = 7519) also completed a standardized laboratory screening program and was followed-up after 12 months. Data were weighted to adjust for non-response, regional distribution and attrition. RESULTS: (1) Doctors and patients sample can be regarded as representative for primary care settings in Germany. (2) The clinician-rated point prevalence of hypertension is highest (35.5%), followed by hyperlipidaemia (29.1%), diabetes (14.1%) and CHD (12.1%); prevalence rates of each disorder as well as their co-incidence rates increase markedly with age. (3) The vast majority (78%) of all patients revealed multiple (3+) behavioural and clinical risk factors. CONCLUSION: The findings of DETECT underline the considerable burden for primary care doctors in managing a highly morbid patient population, with predominantly complex risk factor constellations, in routine care. Our data provide, in unprecedented detail, a basis for calculating age-, gender- and risk-group-adjusted risk-factor profiles in routine care.

Adolescent↗
PubMed2000

[Detection of hepatitis C virus RNA in the tissue of hepatocellular carcinoma by multiple detection system].

OBJECTIVE: Detection of hepatic HCV RNA in hepatocellular carcinoma (HCC) is difficult, since its expression is very low. Several techniques have been established. However, false positive and negative rates still exist. In this study, we applied several conventional and recently developed detection systems to determine the exact effect of HCV RNA on the development of RCC. METHODS: Immunohistochemistry for HCV core antigen and in situ hybridization for HCV RNA had been performed in 39 cases of HCC. IS-RT-PCR was applied for detection and localization of HCV RNA. We extracted microdissected liver tissues to detect HCV RNA separately in cancerous and pericancerous tissues so that the microscopic origin of the amplicons could be controlled. The serological tests including ELISA and RT-PCR for HCV also were performed in all cases. RESULTS: The positive rate by ELISA (30.8%) was not always consistent with that by RT-PCR(43.6%)from serum samples. The latter was much more sensitive and accurate to reflect existence of HCV RNA. Immunohistochemistry showed expression of RCV core antigen in 15 of 39 HCC cases. In pericancerous tissues, the signals were mainly localized in the cytoplasm of hepatocytes. However, translocated expression of HCV core protein was observed in the nuclei of tumor cells, the translocated rate was 73.3%. According to IS-RT-PCR, the positive signals were located mainly in the cytoplasm of cancer cells, the positive rate in HCC was 53.8%, expression of HCV RNA, serum HCV RNA level was detected to be low or negative. This suggested that serum HCV RNA was not always a good reflection of hepatic HCV RNA in HCC tissues. The microdissection RT-PCR described here gave an equal positive rate (59.0%) of HCV RNA in cancerous and pericancerous tissues. CONCLUSIONS: The high detection rate of HCV RNA in HCC specimens even from seronegative patients confirms the important role of HCV RNA during malignant transformation. IS-RT-PCR is a good detection and localization method to visualize HCV RNA in HCC tissues. The microdissection RT-PCR method has a distinct advantage and we anticipate this method will provide an important evidence to determine whether HCV play a direct or indirect role in hepatocarcinogenesis.

Adult↗