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Results for “object detection”

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At least 829 records · Page 46Linked to original sources
PubMed1987

A rapid, objective method for the detection of lymphocytotoxic antibodies using flow cytometry.

Whilst several centres have reported lymphocytotoxic antibody detection using single and dual fluorescent stains with analysis of the fluorescence emitted from the cell population present in a well of a multiwell plate, problems are encountered with cell concentration and light emission overlap. A method we have developed using flow cytometry produces similar values of percentage cell death using single or double staining techniques (correlation coefficient = 0.9896). This method is not influenced by slight variation in cell number or light emission overlap. The effect of introducing red cell impurities into the normal lymphocyte preparation is described.

Antilymphocyte Serum↗
PubMedDate not supplied

Objective motor response onset detection in surface myoelectric signals.

Precise detection of discrete motor events like the onsets of voluntary muscle contractions is a prerequisite for various psychophysiological approaches in sensorimotor system analysis. In biomedical research and clinical diagnosis, motor events frequently are determined from surface electromyographic (SEMG) signals by some computerized detection algorithm. However, little is known about the reliability and accuracy of these methods, which frequently rely on intuitive and heuristic criteria. Therefore, the systematic approach to computerized detection of discrete motor events from SEMG signals presented by this paper fills a basic gap in EMG signal processing. Based upon a dynamic process model for the SEMG signal, a formal detection scheme is established which incorporates the essential processing modules common to the majority of algorithms. In addition, using concepts of statistically optimal change detection in random processes, a new model-based algorithm is presented which serves as a reference for optimum performance. The validity of this concept is demonstrated for the specific example of accurate detection of muscle activation onsets in rapid voluntary contractions; the estimation error (i.e., the deviation between estimated and "true" onset time) was evaluated by statistical simulations for three representative methods. Results show a substantial decrease of performance of traditional methods in the case of highly variable dynamic muscle activation profiles and/or superimposed activation patterns (e.g., due to a secondary motor task simultaneously executed by the same muscle). The model-based approach provided significantly more accurate results, even when the exact model parameters were unknown but estimated from the SEMG signal actually measured. It is concluded that the detection algorithm has to be critically taken into consideration during interpretation of motor events resolved from SEMG signals. The process model together with the corresponding statistically optimal detector represents an efficient tool for selecting appropriate detection algorithms for a particular experimental condition, and it allows a quantitative assessment of their performance.

Algorithms↗
PubMed2006

Prevalence of RET/PTC rearrangements in thyroid papillary carcinomas: effects of the detection methods and genetic heterogeneity.

CONTEXT: RET/PTC rearrangements have been reported in papillary thyroid carcinomas with variable frequency in studies that used different detection methods. OBJECTIVE: Our objective was to determine the role of different detection methods and tumor genetic heterogeneity on RET/PTC detection. DESIGN: Sixty-five papillary carcinomas were analyzed for RET/PTC1 and RET/PTC3 using five detection methods: standard-sensitivity RT-PCR, high-sensitivity RT-PCR, real-time LightCycler RT-PCR, Southern blot analysis, and fluorescence in situ hybridization. RESULTS: RET/PTC rearrangements were detected by standard-sensitivity RT-PCR in 14 tumors. High-sensitivity RT-PCR detected RET/PTC in all of these and in 12 additional cases, where the levels of expression corresponded to one to five positive cells. Real-time LightCycler RT-PCR detected RET/PTC in 12 and Southern blot analysis in 11 tumors. By fluorescence in situ hybridization, 14 tumors were positive, including nine cases with 50-86% positive cells and five cases with 17-35% positive cells. Overall, nine (14%) tumors harbored clonal rearrangements, which were present in the majority of tumor cells and detected by all five methods. Five (8%) cases had subclonal rearrangements present in a smaller portion of tumor cells and detected by most methods. Twelve (18%) tumors had nonclonal RET/PTC that were detected only by high-sensitivity RT-PCR. No other mutations were found in tumors harboring clonal RET/PTC, whereas 60% of tumors with subclonal and 42% of tumors with nonclonal RET/PTC harbored additional mutations. CONCLUSIONS: Our data suggest that broad variability in the reported prevalence of RET/PTC rearrangement is at least in part a result of the use of different detection methods and tumor genetic heterogeneity.

Blotting, Southern↗
PubMed1997

Simultaneous detection of multiple gene expression in mouse and human individual preimplantation embryos.

OBJECTIVE: To detect simultaneously multiple gene expression in mouse and human individual embryos by reverse transcriptase-polymerase chain reaction. DESIGN: Transcripts involved in the insulin-like growth factor (IGF) system were detected in mouse and human preimplantation embryos. SETTING: An academic teaching hospital. MAIN OUTCOME MEASURE(S): Transcripts of the IGF family genes. RESULT(S): In the mouse, genes are expressed differentially and messenger RNA transcripts of maternal origin in nonfertilized ova decline gradually until the initiation of the embryonic genome transcription. Insulin-like growth factor-binding protein-2 (IGFBP)-2, -3, -4, and beta-actin transcripts appear to be initiated at the two- to four-cell stage, whereas IGFBP-1, -5, and -6 transcripts are initiated at later stages. Transcription, once initiated, appears to continue through to the blastocyst stage. In humans, almost all genes of the IGF system were expressed in preimplantation embryos. This is the first report of the assessment of IGF family transcripts in individual embryos, and introduces a novel method for research and clinical diagnosis of preimplantation embryos.

Actins↗
PubMed1997

Transvaginal color Doppler sonography of the ureteral jets: a method to detect ureteral patency.

OBJECTIVE: To evaluate the feasibility of the detection of ureteral jets into the bladder in obstetric-gynecologic patients using transvaginal color Doppler ultrasound. METHODS: Fifty-two women were recruited and categorized into four groups: 1) 20 normal nonsurgical, 2) 17 post-cesarean delivery, 3) 12 post-total abdominal hysterectomy, and 4) three with only one functional kidney or ureter. In the first three groups, transvaginal color Doppler sonography was used to evaluate the time to detection of the first jet and the number of jets in 5 minutes bilaterally. In the last group, the presence or absence of the jet was documented only on the functional side. Statistical analysis was performed using Student t test and analysis of variance followed by Tukey honestly significant difference. RESULTS: Urine jets could be detected bilaterally in all women except for those with only one functional kidney (accuracy 100%). Time to detection of the first jet did not differ significantly in the nonsurgical, cesarean, or hysterectomy patients on either the right side (P = .07) or the left side (P = .43). The total number of jets was similar in the nonsurgical and cesarean patients, but was significantly lower in the hysterectomy group (right side P = .006; left side P = .004). In the women with one functional kidney, the normal side was identified in all cases. CONCLUSION: Transvaginal color Doppler sonography is a simple, accurate technique that can be used to evaluate ureteral jets into the bladder in women. The length of time to detection of the first jet is not affected by the postoperative status. Fewer jets should be expected in women who have undergone hysterectomies. This method should be used when ureteral integrity is in question, especially after surgery.

Adult↗
PubMed1999

Spike detection II: automatic, perception-based detection and clustering.

OBJECTIVES: We developed perception-based spike detection and clustering algorithms. METHODS: The detection algorithm employs a novel, multiple monotonic neural network (MMNN). It is tested on two short-duration EEG databases containing 2400 spikes from 50 epilepsy patients and 10 control subjects. Previous studies are compared for database difficulty and reliability and algorithm accuracy. Automatic grouping of spikes via hierarchical clustering (using topology and morphology) is visually compared with hand marked grouping on a single record. RESULTS: The MMNN algorithm is found to operate close to the ability of a human expert while alleviating problems related to overtraining. The hierarchical and hand marked spike groupings are found to be strikingly similar. CONCLUSIONS: An automatic detection algorithm need not be as accurate as a human expert to be clinically useful. A user interface that allows the neurologist to quickly delete artifacts and determine whether there are multiple spike generators is sufficient.

Adolescent↗
PubMed1996

Predictive value of preschool surveillance in detecting learning difficulties.

OBJECTIVES: The Hall report specified the early detection of mild to moderate learning difficulties as one aim of child health surveillance (CHS). This study examines the efficacy of preschool CHS in the early recognition of children with these disorders. DESIGN: A retrospective case-control study. SUBJECTS: All children (n = 408) with mild to moderate learning difficulties born between 1 July 1983 and 30 June 1984 and resident in North and West Belfast. CONTROLS: 2406 birth records and 150 full child health records controlled for age and geographical area. RESULTS: The prevalence of mild to moderate learning difficulties in North and West Belfast was 16%. Only 6% of children with learning difficulties were identified by the CHS in the preschool period, although the detection rate for children eventually requiring placement in schools for moderate learning difficulties was better. Coverage of the CHS ranged from 90% at the 2 year examination to 98% at the 4 year examination. Perinatal variables associated with learning difficulties after multiple logistic regression analysis were lower social class (odds ratio (OR) 3.9), prematurity < 35 weeks (OR 3.0), male sex (OR 1.6), and birth to an unmarried mother (OR 0.6). Independent preschool variables identified by the CHS were speech delay (OR 3.3), poor parenting skills (OR 4.0), behaviour problems (OR 2.8), enuresis (OR 2.4), poor visual acuity (OR 1.8), and otitis media with effusion (OR 1.4). A statistical model for the early detection of learning difficulties using these risk factors is unable to predict accurately the children who will develop mild to moderate learning difficulties. CONCLUSIONS: The CHS as it existed from 1983 to 1989 in North and West Belfast was poorly sensitive to the detection of mild to moderate learning difficulties despite excellent coverage. An accurate predictive model for learning difficulties could not be developed from the risk factors documented by the CHS.

Case-Control Studies↗
PubMed1999

Bilateral Horner's syndrome: detection and occurrence.

OBJECTIVE: To develop a method for the detection of bilateral Horner's syndrome in patients with bilateral interruption of the cervical sympathetic pathway or widespread autonomic neuropathy. METHODS: Darkness pupil diameters and redilatation times during light reflexes have been recorded with infrared TV pupillometry in 65 healthy subjects, 47 patients with unilateral Horner's syndrome, and 20 patients with bilateral Horner's syndrome. The aetiologies of the last group were diabetic autonomic neuropathy (three cases), amyloidosis (four), pure autonomic failure (PAF) (four), dopamine-beta-hydroxylase deficiency (two), and one case each of hereditary sensory and autonomic neuropathy (HSAN) type III, carcinomatous sympathetic neuropathy, familial dysautonomia, multiple system atrophy, Anderson-Fabry disease, and anterior spinal artery thrombosis at C5,6 and one had had bilateral cervical sympathectomies. RESULTS: Darkness diameters on the affected side were below normal in 12 patients with unilateral Horner's syndrome, the measurement yielding only 26% sensitivity for detection of the condition. By contrast, the time taken to reach three quarter recovery in the light reflex (T3/4) was abnormally prolonged (redilatation lag) in 33 of the same eyes. The measurement yielded 70% sensitivity and 95% specificity for detection of the condition. In 20 cases, diagnosed on clinical grounds as having bilateral Horner's syndrome of various aetiologies, pupil diameters were abnormally small on both sides in five and on one side in three patients. Fourteen of these patients had significant redilatation lag in both eyes, five patients in one eye, and one patient had it in neither eye. Measurement of redilatation lag was therefore a more sensitive diagnostic test than pupil diameter in both unilateral and bilateral Horner's syndrome. CONCLUSIONS: Provided that the pupils are not tonic, bilateral Horner's syndrome can be diagnosed on the basis of redilatation lag. It occurs clinically in some generalised autonomic neuropathies and with interruption of the local sympathetic nerve supplies to the two eyes.

Adult↗
PubMed1994

The early detection of second primary lung cancers by sputum immunostaining. LCEWDG Investigators. Lung Cancer Early Detection Group.

STUDY OBJECTIVE: To determine whether monoclonal antibody (Mab) detection of tumor-associated antigen expressed on sputum epithelial cells precedes clinical presentation of second primary lung cancer. DESIGN SETTING/PARTICIPANTS: Eleven oncology centers collaborate in the accrual of 1,000 patients with stage I non-small cell lung cancer (NSCLC) who had undergone resection. The Mabs examined in this study (624H12, 703D4) detect two promising oncofetal/differentiation markers (ie, a difucosylated Lewis X and a 31-Kd glycoprotein antigen). INTERVENTIONS: Induced sputum specimens are evaluated for quality, then are Papanicolaou and immunostained by independent central laboratories at enrollment and annually thereafter. The predictive value of Mab markers is compared with routine morphologic study for detection of second primary lung cancer during an anticipated 3 years of accrual and 1 year of follow-up. MEASUREMENTS AND RESULTS: Five hundred eighty of an anticipated 1,000 patients have been accrued on schedule. Patients are primarily white (88.6%), former smokers (75.9%), men (55.6%), with a median age of 66.7, and joined the study at an average of 3.7 years following resection of a stage 1 NSCLC (34.4% squamous, 43.6% adenocarcinoma). Central laboratories found less dysplasia and more unsatisfactory specimens (27.3%) than do the accrual institution laboratories. Immunostaining identifies more suspicious cells than does morphologic study. However, only two second primary lung cancers (eight total deaths) have occurred to date. CONCLUSIONS: Halfway through the accrual, we describe the study design and preliminary observations. This study illustrates rational selection of carcinogenesis markers by linkage of marker expression on preneoplastic specimens with subsequent expression on tumor tissue.

Aged↗
PubMed2006

[Detection, enrichment and expansion of T lymphocytes mediating alloresponse based on cytokine].

OBJECTIVE: To detect, enrich and expand the cytokine secreting T lymphocytes after allogeneic PBMNCs stimulation. METHODS: The novel cytokine secretion assay (CKSA) was applied to detect T lymphocytes secreting IFN-gamma at single cell level in human mixed lymphocytes reaction. IFN-gamma secreting T cells were enriched by means of magnetic sorting system and expanded with OKT(3), anti-CD(3)mAb and IL-2 combination. Antigen specificity of the expanded cells was confirmed using enzyme linked immunospot assay. RESULTS: A sizable proportion of IFN-gamma secreting T lymphocytes could be detected [(1.12 +/-0.13)% compared with (0.23 +/-0.07)%] and be further enriched to (67.3 +/-10.5)%, or (93.8 +/-22.1) fold. T lymphocytes could be expanded up to 600-fold within 21-28 days and the specific IFN-gamma response of expanded cells was confirmed with stimulation of the relevant allogeneic PBMNC, which was significantly higher than the irrelevant PBMNC control. CONCLUSION: It is feasible to detect significantly increased IFN-gamma secreting T lymphocytes after allogeneic PBMNCs stimulation based on the CKSA technique at single cell level and these cells can be efficiently enriched and expanded for further research.

Antibodies, Monoclonal↗
PubMed2002

Impact of added biopsy areas on prostate cancer detection: preliminary analysis.

OBJECTIVE: To evaluate variations in prostate cancer detection relevant to the number and areas of biopsy cores. METHODS: Ninety patients with elevated prostate-specific antigen levels, abnormal physical examination findings, or both had ultrasound examinations plus biopsies. Forty-nine patients had 11 biopsies, and 41 patients had 6 biopsies. The numbers of cancers detected were compared on a patient-by-patient basis and by all biopsy sites grouped together. An analysis of the relationship between a positive gray scale sonographic finding and the presence of adenocarcinoma was done. RESULTS: On a patient-by-patient basis, 43% of patients who had 11 biopsies had adenocarcinoma. In patients who had 6 biopsies, 32% had adenocarcinoma. Thirty-eight percent of the additional cancers found in the 11-biopsy group were in 5 additional areas not sampled in the 6-biopsy group. Of the total of 539 biopsy specimens obtained in the 11-biopsy group, 56 (10%) had adenocarcinoma; 43% of these 56 were positive in the 5 additional areas not sampled in the 6-biopsy group. No statistical differences (P > .05) were found for mean age, mean prostate-specific antigen level, and mean volume in the groups with 11 and 6 biopsies. This indicated that the observed difference was not related to any of these factors. Similar pathologic data were found for patients with prostatic intraepithelial neoplasia. CONCLUSIONS: Our data indicate the added value of additional biopsy sites over the usual 6 biopsies to increase the yield of adenocarcinoma and prostatic intraepithelial neoplasia detected. The added biopsy sites of the central and midperipheral glands were areas where additional specimens positive for adenocarcinoma and prostatic intraepithelial neoplasia were obtained.

Adenocarcinoma↗
PubMed1999

Anti-p53 antibodies are rarely detected in serum of patients with rheumatoid arthritis and Sjögren's syndrome.

OBJECTIVE: To detect evidence of abnormalities of the p53 protein in autoimmune diseases. Mutation of the p53 protein may inhibit apoptosis and thereby lead to cancer and possibly play a role in the pathogenesis of autoimmune diseases. METHODS: Serum antibodies to p53 are detected in 30 to 50% of patients with cancer who have p53 mutations. Using an ELISA, we determined the prevalence of anti-p53 antibodies in the serum of 106 patients with rheumatoid arthritis (RA), 72 patients with primary Sjögren's syndrome (SS), and 14 patients with lymphoma complicating SS. The presence of anti-p53 antibodies was also measured in the synovial fluid of 16 patients with RA. Positive sera by ELISA were confirmed by immunoprecipitation. RESULTS: Serum anti-p53 antibodies were detected in 2 of 106 patients with RA. The synovial fluid of one of these 2 patients was also studied and was positive. Anti-p53 antibodies were not detected in the other synovial fluids. Serum anti-p53 antibodies were not detected in 72 patients with primary SS alone, but were present in 2 of 14 patients with lymphoma complicating SS. CONCLUSION: Our results suggest that if p53 mutations have any role in the pathogenesis of some autoimmune diseases, they are rarely associated with the presence of anti-p53 antibodies in patients with RA. In patients with SS, the presence of serum anti-p53 antibodies might be an indirect sign of the development of a lymphoma.

Arthritis, Rheumatoid↗