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PubMed1995

Identification of resting cells by dual-parameter flow cytometry of statin expression and DNA content.

Statin, a 57-kDa nuclear protein, has been recognized as a unique marker of quiescent (G0) cells; specific monoclonal antibodies (MoAb) against statin have been produced and used to label resting cells in tissue sections and in cultured cells. We present an improved method for the identification of G0 cells by dual-parameter flow cytometry of statin expression and DNA content. The appropriate technical conditions were set up by using resting and cycling human fibroblasts as a model cell system. Several fixatives proved to be suitable for the immunocytochemical detection of statin; among them, 70% ethanol was selected because this fixation procedure is suitable for DNA staining with intercalating dyes and is routinely used for the immunolabeling of proliferation markers (such as proliferating cell nuclear antigen [PCNA] and Ki-67) and of bromodeoxyuridine (BrdUrd) incorporation. Following cell permeabilization with detergent, exposure to the antistatin antibody (S-44), and indirect fluorescein isothiocyanate immunolabeling, cells were counterstained for DNA with propidium iodide and analyzed by dual-parameter flow cytometry. In cells from several animal sources (rat thymocytes and C6 glioma cells, mouse 3T3 cells, and human MCF-7 cells), under different experimental conditions, the expression of statin was found to correlate inversely with that of PCNA and Ki-67, and with the BrdUrd labeling index. In dual-parameter flow scattergrams, G0 (statin positive) cells can be discriminated from the potentially cycling (statin negative) G1 cells, i.e., within a cell fraction having the same DNA content. This approach can be envisaged as a powerful tool both for monitoring changes in the resting cell fraction and for investigating the process of G0-G1 transition in unperturbed and drug-treated cell populations.

3T3 Cells↗
PubMed2004

Identification of MRI and 1H MRSI parameters that may predict survival for patients with malignant gliomas.

Although MR imaging (MRI) and MR spectroscopic imaging (MRSI) have been applied in the diagnosis and treatment planning for brain tumors, their prognostic significance has not yet been determined. The goal of this study was to identify pre-treatment MRI and MRSI parameters for patients with malignant glioma that may be useful in predicting survival. Two populations of patients with newly-diagnosed malignant glioma were examined with MRI and three-dimensional proton ((1)H) MRSI. Thirty-nine patients (22 grade 3 and 17 glioblastoma multiforme, GBM) were studied prior to surgery, and 33 GBM patients were studied after surgery but prior to treatment with radiation and chemotherapy. Signal intensities of choline (Cho), creatine (Cr), N-acetyl aspartate (NAA), and lactate/lipid (LL) were estimated from the spectra. Recursive partitioning methods were applied to parameters that included age, histological grade, MRI and MRSI variables to generate survival trees. Patients were grouped into high and low risk categories and the corresponding Kaplan-Meier curves were plotted for comparison between groups. The parameters that were selected by recursive partitioning as being predictive of poor outcome were older age, larger contrast enhancement, higher Cho-to-Cr, higher Cho-to-NAA, higher LL and lower Cr-to-NAA abnormalities. The survival functions were significantly different between the sub-groups of patients obtained from the survival tree for both pre-surgery and post-surgery data. The results of this study suggest that pre-treatment MRI and three-dimensional (1)H-MRSI provide information that predicts outcome for patients with malignant gliomas and have drawn attention to variables that should be examined prospectively in future studies using these techniques.

Adult↗
PubMed1984

On the identification of Michaelis-Menten elimination parameters from a single dose-response curve.

This paper deals with aspects of the numerical identifiability of parameters of a model with a capacity-limited elimination rate using a single dose-response curve, namely, the prospects of being able to identify model parameters with any meaning from real data. The concept of linear bounds, first proposed by Tong and Metzler, is described and it is shown that if the Michaelis-Menten constant Km is greater than all the measured concentration values, approximation by a linear model is appropriate. At the other end of the scale, if Km is small compared with measured concentration values, the nonlinear response approximates to a zero-order curve.

Animals↗
PubMed2004

ST-recovery loop of exercise-induced ST deviation in the identification of coronary artery disease: which parameters should we measure?

This study aimed to characterize the ST-recovery loop and assess which range of heart rates (HRs) best discriminates between patients with and without significant coronary artery stenosis. Bicycle exercise tests were undertaken in 44 men and 18 women with coronary artery disease (CAD) and in 59 controls (26 men, 33 women) in the same age range with no signs of CAD. The ST level and the ST-segment slope were continuously monitored, and changes from rest to peak exercise and to 4 min after exercise, respectively, were calculated. Plotting the ST level against HR gives the STHR loop, characterized by the normalized area (NA(alpha)) circumscribed by the ST level during and after exercise from alpha% to 100% of the HR range. Eight values of alpha between 20% and 90% were investigated, and chest and extremity leads were investigated separately. Optimal alpha was found to be < or =70% in men and < or =30% in women. Change in ST-segment slope was the only parameter that gave significant additional discriminating power in both men and women once the area had been taken into account. We conclude that NA(alpha) for extremity and chest leads have similar weights, and that a substantial part of the STHR loop should be taken into consideration, especially in women. NA(30) was superior to end-exercise ST-depression and STHR loop orientation (as defined by the sign of NA(90)) in both men and women, and to ST/HR index in men, in identifying CAD.

Aged↗
PubMed2001

Accuracy of single ultrasound parameters in detection of fetal growth restriction.

The objective of this study was to evaluate the diagnostic accuracy of different single ultrasonographic parameters in predicting intrauterine growth-restricted (IUGR) babies as defined by Ponderal index at birth. Study sample composed of two sets of data from Iran and Australia. The Iranian sample consisted of 296 Iranian women. All the study women received prenatal care and delivered at Fatemieh Hospital in Shahrood, Iran. The data from 219 Australian fetuses were obtained from the ultrasound section at the Wollongong Hospital in Australia. Ultrasonographic measurements of biparietal diameter (BPD), femur length (FL), head circumference (HC), abdominal circumference (AC), amniotic fluid index (AFI), and Doppler from umbilical arteries (S/D ratio) were obtained. Only those pregnancies were included in which the estimated date of delivery (EDD) by LMP (last menstrual period) agreed within 14 days with the estimated date of delivery determined by the initial ultrasound examination. Sensitivity (SE), specificity (SP), positive predictive value (PPV) and negative predictive value (NPV) were calculated for single proposed ultrasound parameters in the Iranian and Australian samples. When different variables are compared, with a cut-off point at or below the 10th percentile AC and HC had the highest sensitivities in the Australian sample while AC was the most sensitive parameter for IUGR detection in the Iranian sample. BPD has a reasonably high sensitivity at this threshold. The AFI ratio has the lowest sensitivity in predicting IUGR in the Australian sample. Positive predictive values were low in all of the parameters in both the Iranian and Australian samples. By increasing the cut-off for PI to the 20th percentile, the sensitivity of reduced AC increased in the Australian sample while the sensitivity for an abnormal S/D ratio and reduced AFI to identify IUGR decreased. Our results indicate that reduced AC was the best single parameter in discriminating between IUGR and non-IUGR fetuses with the highest sensitivity among the proposed parameters in the both Iranian and Australian sample. However, the PPV of this parameter is low. This means that a high number of false-positive cases are detected using each parameter, which reduces the usefulness of identification. Other ultrasound obstetrical parameters may also have a reasonable level of sensitivity, however, the PPV of all parameters is low. On the whole, our results show that although the examined ultrasonographic criteria may detect a group of fetuses that need close antepartum surveillance, none of these parameters are appropriate enough to be used in isolation in clinical practice. Using single ultrasound parameters does not have high sensitivity and PPVs in detection of fetal growth restriction. This limits accuracy and utility of these tests in the detection of IUGR fetuses.

Abdomen↗
PubMed2005

Identification of critical heterodimer protein interface parameters by multi-dimensional scaling in euclidian space.

Protein subunit dimers are either homodimers (consisting of identical polypeptides) or heterodimers (consisting of different polypeptides). Protein dimers are involved in several cellular processes and an understanding of their molecular principle in complexations (subunit-subunit interaction) is essential. This is generally studied using 3D structures of homodimers and heterodimers determined by X-ray crystallography. However, the current knowledge on subunit interaction is limited due to lack of sufficient 3D dimer structures. It is our interest to study heterodimers using 3D structures to identify interaction parameters that would help in the development of a model to predict heterodimer interaction sites just from protein sequences. The efficiency of such models depends on the weighted contribution of numerous parameters characterizing heterodimer interfaces. Therefore, we studied the salient features of 111 interface parameters in 65 heterodimer structures. In this study, we applied multi-dimensional scaling for dimensionality reduction on these parameters to select the most critical ones that best characterize heterodimer interfaces. The significance of these parameters in subunit interaction is discussed.

Computational Biology↗
PubMedDate not supplied

[On the role of morphological and biochemical criteria in species identification: an example of larval dragonflies of the genus Aeshna].

Dragonflies belong to the group of organisms with numerous well-differentiated species-specific characters at the adult stage, on the one hand, and a significantly smaller number or even the absence of such characters at the early ontogenetic stages. An example of the genus Aeshna is used to show difficulties in revealing morphological and biochemical characters allowing identification of larval dragonflies belonging to closely related species of the family. Distinct morphometric characters can be found only in late-instar larvae. The presence of species-specific proteins in the homogenates of thoracic muscles provides the possibility of using biochemical tests for species identification of larvae. Infestation by parasites has no effects on the biochemical parameters studied. Species identification of the early-instar dragonfly larvae is still problematic.

Animals↗
PubMed1996

Turn/amplitude parameter changes during sustained effort.

Little is known about the effect of sustained effort on turn/amplitude parameters. Therefore, the turn/amplitude analysis was applied at contractions with 50 +/- 5% of the right biceps brachii muscle's maximum force to 31 healthy human subjects (19-67 years old), 15 patients with neuropathies (30-83 years old) and 15 patients with myopathies (16-66 years old). After 3 min of sustained contraction, turns/second (T/S) decreased by 50% in healthy human subjects and by 25% in patients with neuropathies and patients with myopathies. The amplitude/turn (A/T) increased by 25% in healthy human subjects and remained almost unchanged in pathological cases. Compared to its onset values, the ratio A/T:T/S increased by > 150% in healthy human subjects and by 50% in patients with myopathies. With decreasing T/S, the A/T increased in healthy human subjects, decreased in patients with neuropathies and stayed unchanged in patients with myopathies. With this method detection rates of 60% for patients with neuropathies and 67% for patients with myopathies were found. The most reliable turn/amplitude parameters for the identification of pathological cases were the T/S and the A/T. Evaluating these two parameters, the rate of false positive results was 3.2%. The study demonstrated changes during sustained effort to be different between sexes and between healthy human subjects and patients with neuromuscular disorders. It described turn/amplitude analysis during sustained effort as a supplemental electrophysiological device for the detection of patients with neuromuscular disorders. The method is objective, fast and reliable.

Adult↗
PubMed1999

[Prediction of increased levels of androgen in women with acne vulgaris using ultrasound and clinical parameters].

OBJECTIVE: The aim of our study was to identify clinical parameters characterizing women with acne whose dermatological problems are due to increased androgen production. Identification of these parameters would allow to indicate endocrinological examination in only a proportion of women with acne vulgaris. PATIENTS AND METHODS: A total of 54 women with acne vulgaris resistant to local treatment were enrolled in the study. The following clinical parameters were monitored: hirsutism (Ferriman-Gallway score), severity of acne, association of the severity of acne with the menstrual cycle, beginning of manifestations of acne, regularity of the menstrual cycle, presence of alopecia, age at menarche, body weight, BMI and ultrasound investigation of the ovaries. In the standard phase of the cycle, blood was collected to determine the levels of the following hormones: LH, FSH, PRL, TSH, testosterone, androstenedione, DHEA, DHEAS, SHGB. Wilcoxon's robust non-parametric paired test was employed for statistical data analysis. RESULTS: Overall, 33 (61%) women showed increased levels of at least one androgen. An irregular cycle was found in 21 (39%) women, acne severity was associated with the menstrual cycle in 16 (30%) women, 48 (89%) women had acne from menarche, 19 (35%) women had hirsutism; an ultrasound finding of polycystic ovaries was revealed in 32 (59%) women. No significant differences were found between a sub-group of women with levels of at least one androgen above the upper reference limit and the other women in the following variables: age, weight, BMI, age at menarche, ultrasound finding of polycystic ovaries, manifestation of acne from menarche, irregular cycle, hirsutism. The two groups were not different in the severity of acne. Deterioration of acne depending on the menstrual cycle was more often present in women with normal androgen levels. By contrast, a regular menstrual cycle was found to be more frequent in women with raised androgen levels, although the difference was not statistically significant. CONCLUSIONS: Clinical parameters had no association with androgen overproduction. Evaluation of clinical parameters, including severity of acne, does not allow to refer only a proportion of women with acne resistant to local treatment for endocrinological examination.

Acne Vulgaris↗
PubMed1984

Automated flow-cytometric identification of colo-rectal tumour cells by simultaneous DNA, CEA-antibody and cell volume measurements.

A new method for the automated flow-cytometric identification of colo-rectal tumour cells was developed. Fresh tissue is cut mechanically to obtain single cell suspensions. The cells are then incubated with antibodies in an indirect immunofluorescence assay for CEA (carcino-embryonic antigen) on the cell surface, and counterstained with the DNA stain propidium iodide. Monosized latex particles are added as internal standard, then cell volume, antibody fluorescence and DNA are measured simultaneously in a FLUVO-METRICELL flow cytometer. A FORTRAN IV computer program was used to determine whether aneuploid cells or cells with high density of CEA on their surface were present in the sample. All relevant data were stored automatically in a self updating data base, which is important for quality control and automated thresholding. The samples were taken from 120 different patients. A tumour sample and a sample of healthy adjacent mucosa of the same patient were available in 88 patients. 97.5% of all tumours and 88.6% of the normal mucosa samples were correctly identified. This shows for the first time that the majority of colo-rectal tumour samples can be identified by a flow cytometric measurement with automated data evaluation. The identification of tumour samples was substantially better when based on the measurement of the three parameters, compared with identification by aneuploidy (59%) or by the CEA antibody alone (91%). It will be possible to automate the measurement of the samples.

Antibodies↗
PubMed1998

Pathologic parameters in the diagnosis and prognosis of primary cutaneous melanoma.

Significant progress has been made in the last 10 years on the identification of histologic parameters that are independent predictors of melanoma prognosis, immunohistochemical markers of cells of melanocytic origin and changes in adhesion molecules, cytoskeletal proteins, growth factor receptors, cell signaling, and nuclear proliferation proteins associated with tumor progression. Histologic criteria may never be completely sufficient to predict behavior accurately, because the fundamental change that renders a cell aggressive may not be morphologically reflected and may require immunohistochemical or other molecular markers to establish behavior. To date, it is humbling that no immunohistochemical or molecular marker provides a greater predictable value for aggressive behavior than does the simple calibrated ocular micrometer to measure tumor thickness. Nevertheless, development of multiple histologic parameters with the concept of nontumorigenic RGP and tumorigenic VGP provides a reliable statistical model to predict metastases. Fortunately, nontumorigenic RGP melanomas with greater than 75% regression are rare. Thus, individual patients with melanoma without regression and without the tumorigenic VGP can be given reasonable assurance of 100% survival. Nevertheless, this assurance is based on a statistical model with a finite population studied. Additional studies are needed to confirm this model, as well as more definitive markers to precisely predict outcome for those individuals with tumorigenic VGP melanoma.

Biomarkers, Tumor↗
PubMed2006

Rapid protein identification using direct infusion nanoelectrospray ionization mass spectrometry.

Current protein identification techniques are largely based on MALDI-TOF mass fingerprinting and LC-ESI MS/MS sequence tag analysis. Here we describe an improved method for rapid protein identification that uses direct infusion nanoelectrospray quadrupole time-of-flight (nanoESI QTOF) MS. Protein digests were analyzed without LC separation using nanoESI on a QSTAR XL MS/MS system in information dependent data acquisition mode. The protein identification conditions and parameters were extensively evaluated with in-solution and in-gel digested protein samples. Rapid identification of proteins was achieved and compared directly to the results obtained on the same samples using nanoflow HPLC-MS/MS on the QSTAR system. The increased throughput, reproducibility, the high data quality, and the ease of use make the direct infusion system an efficient and affordable technique for protein identification analysis.

Chromatography, High Pressure Liquid↗
PubMed1985

Quantitative characterization of blood rheological behavior in transient flow with a model including a structure parameter.

Transient rheological behavior of blood which involves non newtonian viscosity, elasticity and thixotropy can be modelized with a Maxwell rheological state equation which depends on a structure parameter having dimension of a shear rate. Identification of the model parameters leads to use an exponential apparent shear rate step and to use recursive filters for taking into account the impulse response of the viscometer servo-control device. Typical results for a normal blood sample are given.

Blood Physiological Phenomena↗
PubMed1999

A hierarchical Bayesian approach to age-specific back-calculation of cancer incidence rates.

We propose a Bayesian hierarchical model to estimate age-specific cancer incidence per year from age-specific cancer mortality. The model is based upon the empirical Bayesian approach of Liao and Brookmeyer (1995) and extends that model by consideration of the dependence on age. The incident cases per year are considered as observations from a discrete-time stochastic process following an autoregressive structure within a Poisson regression model. The model assumes that the survival probability among those with cancer is known. We have investigated the sensitivity of the model to the choice of this distribution and have found that this is the most sensitive part of the model. By comparison the predictions of the model are relatively robust to changes in other key areas, such as the number of years an incident case contributes before death, assumptions about parameter equality for identification and the initial prior distributions. The proposed methodology has been investigated using lung cancer mortality data from Scotland. Parameter estimates were obtained through Markov chain Monte Carlo methods, implemented using BUGS.

Age Factors↗
PubMed1995

Improved prognostication in small (pT1) breast cancers by image cytometry.

Feulgen-stained samples from 460 small (pT1) primary breast cancers were investigated by means of an image analysis system. Several DNA, morphometrical and textural parameters were evaluated for each patient, and the prognostic meaning of these parameters was then investigated by the Cox regression analysis. As prognostic criterion a distant recurrence-free survival of five years was considered. All investigated DNA- and morphometrical parameters as well as several textural parameters showed a significant univariate correlation with the clinical course. In a multivariate approach the axillary nodal status was the most important prognostic parameter, followed by a morphometric parameter (anisokaryosis) and two textural parameters (runlength and co-occurrence). None of the DNA histogram derived parameters could add prognostic information in this multivariate approach. By the linear combination of the four selected variables, an individual prognostic factor was calculated. Using this factor the patients could be split into several groups according to their risk for distant metastases. Thus a low risk group of pT1 patients could be identified with a distant recurrence rate of only 2% after 5 years, and also a group of patients with a considerably worse prognosis and a 5-year distant recurrence rate of 53%. In contrast, using the nodal status as single parameter allows the identification of a low risk group of patients (pN0pT1) with a distant recurrence rate of 10.6%. Therefore, morphometrical and textural parameters can provide powerful prognostic information in small breast carcinomas and may allow a better selection of patients for adjuvant therapy.

Aged↗
PubMed2006

Feasibility study on identification of green, black and Oolong teas using near-infrared reflectance spectroscopy based on support vector machine (SVM).

Near-infrared (NIR) spectroscopy has been successfully utilized for the rapid identification of green, black and Oolong teas. The spectral features of each category are reasonably differentiated in the NIR region, and the spectral differences provided enough qualitative spectral information for identification. Support vector machine as a pattern recognition was applied to attain the differentiation of the three tea categories in this study. The top five latent variables are extracted by principal component analysis as the input of SVM classifiers. The identification results of the three tea categories were achieved by the RBF SVM classifiers and the polynomial SVM classifiers in different parameters. The best identification accuracies were up to 90%, 100% and 93.33%, respectively, when training, while, 90%, 100% and 95% when test. It was obtained using the RBF SVM classifier with sigma=0.5. The overall results ensure that NIR spectroscopy combined with SVM discrimination method can be efficiently utilized for rapid and simple identification of the different tea categories.

Feasibility Studies↗
PubMedDate not supplied

Application of HSV colour system in identification by colour of biological objects on the basis of microscopic images.

This paper demonstrates preliminary image processing with the aim of obtaining invariant signs for identification by colour. For this purpose we have used microscopic images of cell structures in coloured peripheral blood smears. The main parameter for the identification is the colouring of the respective cell structures on the basis of which we have created histograms by hue for the available cell types.

Algorithms↗