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At least 1,423 records · Page 79Linked to original sources
PubMed2002

Laser-induced fluorescence spectroscopy for in vivo diagnosis of non-melanoma skin cancers.

BACKGROUND AND OBJECTIVES: Laser-induced fluorescence spectroscopy is a non-invasive technique previously used for detection of cancer in a variety of organ systems. The objective of this study was to determine whether in vivo laser-induced fluorescence spectroscopy alone at the visible excitation wavelength of 410 nm could be used to detect non-melanoma skin cancers. STUDY DESIGN/MATERIALS AND METHODS: The system consisted of a nitrogen/dye laser tuned at 410 nm, an optical multichannel analyzer, and a fiber optic probe for excitation of tissue and collection of fluorescence emission. Two hundred and seventy nine measurements were performed from normal and abnormal tissues in 49 patients. Patients were classified as having either skin types I, II, or III. Biopsy of the abnormal tissues were then performed. Each measurement was assigned as either normal, basal cell carcinoma (BCC), squamous cell carcinoma (SCC), pre-cancerous, or benign. Total emission photon count was used as the discriminating index. A threshold value was calculated to separate normal tissue indices from indices of cancer tissues. The classification accuracy of each data point was determined using the threshold value. RESULTS: Cancers were classified 93, 89, and 78% correctly in patients with skin types I, II, and III, respectively. Normal tissues were classified 93, 88, and 50% correctly in patients with skin types I, II, and III, respectively. Using the same threshold, pre-cancerous spectra were classified 78 and 100% correctly in skin types I and III, respectively. Benign lesions were classified 100, 46, and 27% correctly in patient with skin types I, II, and III, respectively. CONCLUSIONS: In vivo laser induced fluorescence spectroscopy at 410 nm excitation and using the intensity of emission signal is effective for detection of BCC, SCC, and actinic keratosis, specially in patients with light colored skin.

Basal Cell Carcinoma↗
PubMed1989

Effects of exposure time and pulse parameters on CO2 laser osteotomies.

Two sets of experimental linear osteotomies were performed on frozen cortical bone by means of a high-power industrial CO2 laser in the rapid superpulsed mode, varying the velocity of the operating table, the mean power of the laser beam, the pulsewidth, the pulse repetition rate, and the peak power. Both the depth and the width of the osteotomies were inversely related to the velocity and directly related to the mean power and to the pulsewidth, but they were not affected by changes in the repetition rate. The depth/width ratio, which describes the profile of the osteotomies, was affected by the mean power only. These data permit greater accuracy in the planning of laser osteotomies in cortical bone when using the rapid super-pulsed mode.

Animals↗
PubMed2005

Holistic differential analysis of embryo-induced alterations in the proteome of bovine endometrium in the preattachment period.

During the peri-implantation period, molecular signaling between embryo and endometrium (layer of tissue lining the uterus lumen) is supposed to be crucial for the maintenance of pregnancy. To investigate embryo-induced alterations in the proteome of bovine endometrium in the preattachment period (day 18), we used monozygotic cattle twins (generated by embryo splitting) as a model eliminating genetic variability as a source for proteome differences. One of the twins was pregnant after the transfer of two in vitro produced blastocysts, while the corresponding twin received a sham-transfer and served as a nonpregnant control. The two-dimensional fluorescence difference gel electrophoresis (2-D DIGE) analysis of the endometrium samples of three twin pairs (pregnant/nonpregnant) revealed four proteins with significantly higher abundance (p < 10(-9)) in each sample derived from the pregnant animals: Rho GDP dissociation inhibitor beta; 20 alpha-hydroxysteroid dehydrogenase (20 alpha-HSD); soluble NADP(+)-dependent isocitrate dehydrogenase 1; and acyl-CoA-binding protein. To verify the accuracy of the 2-D DIGE quantification, the abundances of 20 alpha-HSD were quantified by a targeted cleavable isotope-coded affinity tag (ICAT) approach. The mass spectrometry-based ICAT quantification matched perfectly the results obtained by 2-D DIGE quantification, demonstrating the accuracy of our data. These results demonstrate that our model (monozygotic twins) in combination with the appropriate analytical tools is particularly suitable for the detection of the proteins involved in the embryo-maternal interactions.

Albumins↗
PubMed2006

Assessing the utility of SELDI-TOF and model averaging for serum proteomic biomarker discovery.

The SELDI-TOF technique was used to profile serum proteins from Type 1 diabetes (T1D) patients and healthy autoantibody-negative (AbN) controls. Univariate and multivariate analyses were performed to identify putative biomarkers for T1D and to assess the reproducibility of the SELDI technique. We found 146 protein/peptide peaks (581 total peaks discovered) in human serum showing statistical differences in expression levels between T1D patients and controls, with 84% of these peaks showing technical replication. Because individual proteins did not offer great power for disease prediction, we used our model averaging approach that combines the information from multiple multivariate models to accurately classify T1D and control subjects (88.9% specificity and 90.0% sensitivity). Analyses of a test subset of the data showed less accuracy (82.8% specificity and 76.2% sensitivity), although the results are still positive. Unfortunately, no multivariate model could be replicated using the same samples. This first attempt of high throughput analyses of the human serum proteome in T1D patients suggests that model averaging is a viable method for developing biomarkers; however, the reproducibility of SELDI-TOF is currently not sufficient to be used for classification of complex diseases like T1D.

Adolescent↗
PubMed1993

Data monitoring committees and capturing relevant information of high quality.

The integrity and credibility of randomized clinical trials, designed to provide a definitive evaluation of therapeutic interventions, can be substantially enhanced if periodic review of results on the relative efficacy of treatments is conducted by a data monitoring committee (DMC). The role of the DMC can include some important activities which promote obtaining relevant information of high quality. In the final stage of study development, these include review of protocol-specified study objectives and design, and review of procedures planned for capturing high-quality data and for reporting to the DMC. At analyses during the trial, these include careful review of data completeness and accuracy to assist in early detection and resolution of evolving problems.

Clinical Trials as Topic↗
PubMed1993

Analysis of cleavage-site patterns in protein precursor sequences with a perceptron-type neural network.

A method for feature extraction from protein sequences has been developed which is based on an artificial neural filter system. Amino acid sequences are analyzed with regard to physicochemical residue properties. This alternative representation of a sequence allows an interpretation of the networks' weight values in a comprehensive and biochemically meaningful way by displaying the optimized network weights in Hinton diagrams. Signal peptidase cleavage sites of E.coli periplasmic proteins, human mitochondrial precursors and chloroplast precursors from spinach have been investigated. The network for E.coli periplasmic protein precursors classified both training and test data with 100% accuracy. The interpretation of its network weights clearly confirms the "-3,-1 rule" and the existence of a hydrophobic core region starting at position -6. Further striking features and dominant positions can be found for all three types of cleavage sites.

Algorithms↗
PubMed1990

Risk factors for adverse drug reactions--epidemiological approaches.

Age by itself is not an important risk factor for ADRs. Age-related changes are the consequence of a number of individual factors, for example morbidity associated with polypharmacy, decline in renal or liver function in the elderly, hypoalbuminaemia, reduced body weight, etc. The relationship between gastrointestinal bleeding and non-steroidal anti-inflammatory drugs can be assessed globally in large cohort studies with access to computerized data, but complete accuracy requires access to the original patient records. The increase in the risk of GI bleeding in users of NSAIDs and aspirin was 50% above that in non-users. About a quarter of ADRs in hospitalized patients seem not to arise from purely pharmacological mechanisms. They are mainly due to allergic, anaphylactoid, or idiosyncratic reactions and to intolerance. In such non-pharmacological reactions, the time of exposure, reaction time, and even dosage may be important factors in identification of the causal drug. The use of benzodiazepines can be optimized by taking into account potency, time of action and the different syndromes encountered after withdrawal. Following long-term use problems of relapse and rebound are being increasingly recognized, in addition to organic withdrawal symptoms. In psychiatric patients extrapyramidal disorders due to neuroleptics are common. The rates of these ADRs differ markedly between various drugs, even after dosages and co-medications are taken into account. Epidemiological screening for potentially carcinogenic drugs can only be done in large cohorts of patients with pre-recorded full information sets as may be found in an HMO (Health Maintenance Organization). The findings of several such studies have been published in specialist cancer journals.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1977

The functional independence of response latency and accuracy: implications for the concept of conceptual tempo.

Kagan (1965a) developed the concepts of impulsive and reflective cognitive styles (conceptual tempo) to add a new dimension to the understanding and assessment of human intelligence. Although latency (the principal component of conceptual tempo) is negatively correlated with academic performance, it may not be necessary to modify latency in order to modify accuracy.. With 40 disadvantaged preschool children, it was found that reinforcing long latencies in choice tasks did not increase accuracy and vice versa, and that reinforcing both long latencies and accuracy was no more effective than reinforcing accuracy alone. These data were used to question the usefulness of the construct of conceptual tempo.

Achievement↗
PubMed1991

Maximum entropy and drug absorption.

The application of maximum entropy to the calculation of drug absorption rates was introduced in an earlier paper. Here it is developed further, and the whole procedure is presented as a problem in scientific inference to be solved using Bayes' theorem. Blood samples do not need to be taken at equally spaced intervals, and no smoothing, interpolation, extrapolation, or other preprocessing of the data is necessary. The resulting input rate estimates are smooth and physiologically realistic, even with noisy data, and their accuracy is quantified. Derived quantities such as the proportion of the dose absorbed, and the mean and median absorption times, are also obtained, together with their error estimates. There are no arbitrarily valued parameters in the analysis, and no specific functional form, such as an exponential or polynomial, is assumed for the input rate functions.

Biological Availability↗
PubMed1985

The microcomputer: an aid to paediatric parenteral nutrition.

Approximately 50% of the pharmacy man-hours committed to providing a parenteral nutrition service at the Children's Hospital, Birmingham were spent in calculations, form filling and record keeping. An increasing demand for the service, with no extra staff available, meant that the service had to be made more efficient. A 90% time saving was achieved by using a microcomputer to free the pharmacy staff from many of the laborious mathematical and clerical chores. The program was developed by a member of the nutritional care team; this meant that it was designed with the specific needs of the service in mind. In addition the detail and accuracy of patient data recording have been greatly improved.

Child↗
PubMed1995

An automated patient registration and treatment randomization system.

Centralized patient registration and treatment randomization for multicenter clinical trials has many advantages over other approaches. Our Automated Patient Registration and Treatment Randomization system is a fully automated Interactive Voice Response, microcomputer-based application which can operate unattended and is continuously available to provide patient registration and treatment randomization. Several techniques are employed to ensure security of the system and validity and accuracy of the data. Several randomization methods were implemented to support different study designs including balanced block randomization, stratified permuted block scheme, and a sophisticated randomization design based on the minimization method and Zelen's adaptive randomization method for institution balancing.

Clinical Trials as Topic↗
PubMed1999

Physical activity monitoring based on accelerometry: validation and comparison with video observation.

The objective of this feasibility study is to evaluate the use of the 'Physilog' device, an ambulatory physical-activity recorder based on acceleration measurement, for the monitoring of daily physical activities. Accelerations measured at the level of the chest and the thigh are recorded by Physilog over a period of 1 h in five normal subjects. A specially designed studio-like room allowing the performance of most usual activities of everyday life is used. A video film synchronised with the Physilog is obtained for each subject to check the accuracy of the data derived from Physilog. Based on the analysis on the average and the deviation of the acceleration signal, an algorithm is developed to classify the activities in four categories, i.e. lying, sitting, standing and locomotion. Compared with the video observations, the results from the algorithm show an overall misclassification of 10.7%, which is mainly due to confusion between dynamic activities and the standing posture. In contrast, the misclassification between postures is negligible. It is concluded that Physilog can be used in the clinical setting for the reliable measurement and long-term recording of most usual physical activities.

Activities of Daily Living↗
PubMed1983

Diuretic radionuclide urography.

Diuretic radionuclide urography is a modification of conventional renography which utilizes the administration of intravenous furosemide to distinguish dilated, non-obstructed, hydronephrotic systems from those with significant mechanical obstruction. Diagnostic patterns are derived from computer generated time-activity histograms that depict the accumulation and washout of radiotracer before and after diuretic injection. In dilated but non-obstructed systems, diuresis produces a decline in activity. In obstructed systems, there is a failure of radiotracer washout in response to diuresis and no decline in activity is observed. The procedure is applicable to patients of all ages with suspected upper urinary tract obstruction. Clinical and experimental data support the accuracy and utility of this methodology and define its limitations and pitfalls.

Animals↗
PubMed2001

Predicting the voluntary arm forces in FES-assisted standing up using neural networks.

For individuals with paraplegia, standing up requires activation of paralyzed leg muscles by an artificial functional electrical stimulation (FES) controller and voluntary control of arm forces by the individual. Any knowledge of such voluntary control, particularly its prediction, could be used to design more effective FES controllers. Therefore, artificial neural network models were developed to predict voluntary arm forces from measured angular positions of the ankle, knee, and hip joints during FES-assisted standing up in paraplegia. The training data were collected from eight paraplegic subjects in repeated standing-up trials, and divided into two categories for training and validation. The predictions of the models closely followed both the training and validation data, showing good accuracy and generalization. The comparison of the models showed that, although there are striking similarities among the voluntary controls adopted by different subjects, each subject develops his/her own 'personal strategy' to control the arm forces, which is consistent from trial to trial. The level of consistency was dependent on the experience in using FES, injury level, body weight, and other subject-specific parameters.

Adult↗
PubMed2006

[Diagnostic strategies in cases of suspected periprosthetic infection of the knee. A review of the literature and current recommendations].

Reliable confirmation of periprosthetic infection after total knee arthroplasty is a diagnostic challenge. The present work reviews published data evaluating the available diagnostic tools. Erythrocyte sedimentation rate and C-reactive protein serum levels are relatively sensitive methods with rather low specificity towards periprosthetic infection and are mainly applied to exclude infection. Studies evaluating scintigraphic methods--especially white cell scans--provide inconsistent data with varying accuracy. Consequently, white cell scans cannot be recommended as standard methods. Immunoscintigraphy with antigranulocyte antibodies and FDG-PET scans demonstrated promising results with particularly high sensitivities, but have to be validated in larger studies. Microbiological evaluation of joint aspirates proved high specificity for periprosthetic infection. However, an average of 20% of infected cases remained undetected. Nevertheless, aspiration is widely recommended for preoperative isolation of the infecting organism. Intraoperative frozen sections demonstrated excellent specificity with good sensitivity. The real accuracy of intraoperative culture and permanent histology cannot be determined due to the missing golden standard; however, a combination of both methods is recommended to define the final diagnosis. Large studies validating both methods and criteria for the final diagnosis of periprosthetic infection are necessary to optimize the diagnostic algorithm.

Arthroplasty, Replacement, Knee↗
PubMed2002

Laboratory development and field evaluation of a new diffusive sampler to collect nitrogen oxides in the ambient air.

Diffusive samplers for the determination of NO(x) and NO2 based on collection on a coated carbon paper filter have been developed. NO is first oxidized to NO2 and then collected on the reactive surface. When NO2 and NOx samplers are exposed simultaneously, NO can be calculated by difference. The sampler has been derived from a Palmes design as recently modified by Bertoni et al. for the determination of BTX (benzene, toluene, xylenes). Laboratory tests were conducted in controlled atmosphere to evaluate linearity, uptake rate, face velocity effects, sample stability, influence of relative humidity, precision and accuracy. The samplers are capable of reliable measurements of the two species at common levels of a polluted atmosphere in urban settings yielding average concentration levels over 1 month and beyond. The uptake rate of NO2 was found to be 11.7 mL/min in a very good agreement (within 5%) with the value calculated from theory. The measured uptake rate for NO(x) was determined in experiments involving sampling at different concentration levels in comparison to chemiluminescence (CL) measurements. The precision of the measurements for co-located passive samplers was better than 5%. The accuracy of the data collected is within +/-20% of the actual value measured by CL. The laboratory and field results show that the NO(x) and NO2 samplers meet the data quality goal requested by the first EU Directive 1999/30/EU for these pollutants.

Journal Article↗
PubMed2005

Development and field evaluation of a new diffusive sampler for hydrogen sulphide in the ambient air.

A diffusive sampler for the determination of hydrogen sulphide (H2S) based on collection on a paper filter coated with silver nitrate followed by optical densitometric determination of the metal sulphide was developed. Laboratory tests were conducted in controlled atmosphere to evaluate linearity, uptake rate, face velocity effects, sample stability, influence of relative humidity and of interferents, precision and accuracy. The measured uptake rate for H2S was determined in experiments involving sampling at different concentration levels in comparison to a wet standard colorimetric technique. The precision of the measurements for co-located passive samplers was lower than 15%. The accuracy of the data collected is within 20% of the actual value measured by the wet method. The sampler is capable of reliable measurements of H2S at common levels of a polluted atmosphere in urban settings yielding average concentration levels over one month and beyond. Diffusive sampling can be adopted to analyse in detail the temporal and spatial trends of H2S concentration in ambient air and in specific historic buildings or in museums.

Journal Article↗
PubMed2000

Determination of polycyclic aromatic hydrocarbons in marine sediments using a new ASE-SFE extraction technique.

In order to determine PAHs in marine sediment samples by GC/MS(SIM) a new extraction approach of ASE-SFE was evaluated using combined accelerated solvent extraction (ASE, dynamic and static mode) and supercritical fluid extraction (SFE, dynamic mode) without further purification of the sample. The solvents used for ASE-SFE were methylene chloride and carbon dioxide. The recovery data, precision and accuracy of the whole method were evaluated statistically. The average recoveries of PAHs, based on deuterated internal standards were 77% for 2-3-ring PAHs, 85% for 4-ring PAHs, 88% for 5-ring PAHs and 97% for 6-ring PAHs. The extraction time required for the ASE-SFE technique was 30 min, which is longer than in the case of independent use of ASE and shorter compared to SFE. ASE-SFE recoveries of PAHs from SRM marine sediment are comparable for (2-3-ring, 4-ring PAHs) or higher (5-ring, 6-ring PAHs) than reported for the conventional extraction methods of ASE and SFE. Method detection limits of (MDL) were statistically estimated. MDL values obtained for 15 PAHs compounds vary between 0.06 ngg(-1) and 3.54 ngg(-1).

Automation↗