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PubMed1994

Simulation of multiple isotropic spin-trap EPR spectra.

A computer program has been developed for fitting EPR data with multiple free radicals as formed in biochemical and chemical spin-trapping systems. Simulation of these spectra requires as many as 40 independent parameters, creating a chaotic analysis environment. Accurate simulation of these systems is essential for correct identification of the free radicals, which often show only slight differences in spin-Hamiltonian parameters. This method consists of rule-based perturbations with trial and error calculations and has proven successful in several applications. Details of the algorithm, example data, and a discussion of the difficulties of this analysis are presented in this report.

Algorithms↗
PubMed1998

Improved identification of mycobacteria by using the microbial identification system in combination with additional trimethylsulfonium hydroxide pyrolysis.

The MIDI automated Microbial Identification System (MIS) uses gas chromatography (GC) analysis of whole-cell fatty acid methyl esters (FAMEs) between 9 and 20 carbons in length to characterize a wide range of bacterial genera and species, including mycobacteria. Mycolic acid cleavage products (MACPs) with chain lengths of C22 to C26 are not released by MIDI sample preparation of mycobacteria. Therefore, the MIS library search report often matches several mycobacterial species without any significant difference in the similarity indices. The problem is solved by adding trimethylsulfonium hydroxide (TMSH) instead of sodium sulfate in the last step of sample preparation, thus allowing the identification of MACPs in addition to FAMEs. Only one GC run parameter has to be changed: the temperature program must be extended from 260 to 310 degrees C. The MIS library search report for the identification of bacteria is not disturbed by TMSH. The combination of conventional library search report with the information of typical MACP patterns yields significantly better discrimination of mycobacterial species than the MIDI method allows.

Chromatography, Gas↗
PubMed1992

Decomposition-based qualitative experiment design algorithms for a class of compartmental models.

Qualitative experiment design, to determine experimental input/output configurations that provide identifiability for specific parameters of interest, can be extremely difficult if the number of unknown parameters and the number of compartments are relatively large. However, the problem can be considerably simplified if the parameters can be divided into several groups for separate identification and the model can be decomposed into smaller submodels for separate experiment design. Model decomposition-based experiment design algorithms are proposed for a practical class of large-scale compartmental models representative of biosystems characterized by multiple input sources and unidirectional interconnectivity among subsystems. The model parameters are divided into three types, each of which is identified consecutively, in three stages, using simpler submodel experiment designs. Several practical examples are presented. Necessary and sufficient conditions for identifiability using the algorithm are also discussed.

Algorithms↗
PubMed1997

Identification of high- and low-risk patients before liver transplantation: a prospective cohort study of nutritional and metabolic parameters in 150 patients.

The clinical relevance of malnutrition and hypermetabolism in end-stage liver disease, as well as their effects on survival after liver transplantation (LTx), are largely unknown. This study investigates the prognostic value of nutritional and metabolic parameters obtained before LTx for survival after LTx. One hundred fifty patients with end-stage liver disease undergoing LTx were assessed prospectively and followed for a mean period of 46 +/- 16 months after LTx. All patients were randomized into a study group and a validation group, each comprising 75 patients. Body composition analysis (24-hour urinary creatinine excretion, anthropometry, bioelectrical impedance analysis), deviation of measured from predicted resting energy expenditure (deltaREE), year of transplantation, and several variables known to be of prognostic relevance in patients with liver disease undergoing conservative treatment were analyzed. Kaplan-Meier and log rank analysis showed that hypermetabolic patients (deltaREE > +20%) and patients with a body cell mass (BCM) < 35% of body weight tended to have reduced survival after LTx. A risk profile on the basis of deltaREE and BCM identified patients with high risk (5-year survival rate, 54%) and low risk (5-year survival rate, 88%; P < .01). The predictive power of this risk profile was independent of the presence of ascites and clinical edema, and its validity was confirmed in the validation group (P < .01). The Child-Pugh score was not of prognostic value. We conclude that a poor nutritional state, as well as hypermetabolism, adversely affects survival after LTx. These potentially treatable presurgical factors deserve close attention in interventional studies.

Adult↗
PubMed2005

Toward identification of the compound I reactive intermediate in cytochrome P450 chemistry: a QM/MM study of its EPR and Mössbauer parameters.

Quantum mechanical/molecular mechanical (QM/MM) methods have been used in conjunction with density functional theory (DFT) and correlated ab initio methods to predict the electron paramagnetic resonance (EPR) and Mossbauer (MB) properties of Compound I in P450(cam). For calibration purposes, a small Fe(IV)-oxo complex [Fe(O)(NH(3))(4)(H(2)O)](2+) was studied. The (3)A(2) and (5)A(1) states (in C(4)(v)() symmetry) are found to be within 0.1-0.2 eV. The large zero-field splitting (ZFS) of the (FeO)(2+) unit in the (3)A(2) state arises from spin-orbit coupling with the low-lying quintet and singlet states. The intrinsic g-anisotropy is very small. The spectroscopic properties of the model complex [Fe(O)(TMC)(CH(3)CN)](2+) (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) are well reproduced by theory. In the model complexes [Fe(O)(TMP)(X)](+) (TMP = tetramesitylporphyrin, X = nothing or H(2)O) the computations again account for the observed spectroscopic properties and predict that the coupling of the (5)A(1) state of the (FeO)(2+) unit to the porphyrin radical leads to a low-lying sextet/quartet manifold approximately 12 kcal/mol above the quartet ground state. The calculations on cytochrome P450(cam), with and without the simulation of the protein environment by point charges, predict a small antiferromagnetic coupling (J approximately -13 to -16 cm(-)(1); H(HDvV) = - 2JS(A)S(B)) and a large ZFS > 15 cm(-)(1) (with E/D approximately 1/3) which will compete with the exchange coupling. This leads to three Kramers doublets of mixed multiplicity which are all populated at room temperature and may therefore contribute to the observed reactivity. The MB and ligand hyperfine couplings ((14)N, (1)H) are fairly sensitive to the protein environment which controls the spin density distribution between the porphyrin ring and the axial cysteinate ligand.

Cytochrome P-450 Enzyme System↗
PubMed1993

Identification of patients with impaired hepatic drug metabolism using a limited sampling procedure for estimation of phenazone (antipyrine) pharmacokinetic parameters.

Phenazone (antipyrine) 1g was given by short intravenous infusion to 62 study participants (10 healthy drug-free volunteers and 52 patients with chronic liver disease). A Bayesian approach was developed to determine the individual pharmacokinetic parameters of phenazone. Statistical characteristics of the population pharmacokinetic parameters were first evaluated for 30 patients. When combined with 1 plasma drug concentration from members of the second group, these led to a Bayesian estimation of individual pharmacokinetic parameters for the remaining 32 individuals. Total clearance computed by Bayesian estimation was compared with maximal likelihood estimation of this parameter, the classical procedure. No statistically significant differences were found. Performance of the developed methodology was evaluated by computing bias and precision. The mean error was 0.0477 L/h. The precision of the prediction of this parameter (0.155 L/h) remained lower than the interindividual standard deviation (0.765 L/h). This procedure enables the estimation of individual pharmacokinetic parameters for phenazone. In this study, numerous laboratory tests were performed. A highly significant correlation (p < 0.001) was found between phenazone clearance and the prothrombin time, albumin, gamma-globulin, factor V, antithrombin III, fibrinogen and total bilirubin. Discriminant analysis determined that protein, alkaline phosphatase, creatininaemia and gamma-globulin had more significant discriminating power and gave better prognostic results than those seen with the Child-Pugh test.

Adult↗
PubMed1999

Identification of Theileria buffeli/orientalis and Babesia bigemina in Apulian cattle using molecular techniques and study of changes in blood parameters.

Recently several cases of theileriosis due to the haemoprotozoan Theileria buffeli/orientalis have been recorded in the Apulian region, Italy. In this area other tick-borne pathogens were usually identified such as Anaplasma marginale and Babesia bigemina. Outbreaks were recorded showing that these pathogens can be observed separately or in mixed infections. Sub-clinical cases and carrier animals were also previously identified. A lack of specific techniques could not rule out the presence of other haemoparasites such as T. annulata, B. divergens, B. bovis, Ehrlichia phagocytophila and E. bovis. Moreover little is known about the tick species involved in the dissemination of these diseases. Therefore more powerful techniques to specifically identify Theileria or Babesia species have been recently developed. A PCR technique and reverse line blotting (RLB) system to specifically identify six Theileria species and three Babesia species were used. T. buffeli/orientalis and B. bigemina were the only pathogens observed in the targeted animals. The authors also present some changes in blood parameters for the animals followed during this study.

Animals↗
PubMed1989

Immunoelectron microscopic identification of human AA-type amyloid: exploration of various monoclonal AA-antibodies, methods of fixation, embedding and of other parameters for the protein-A gold method.

Using the postembedding protein-A gold technique ten monoclonal antibodies directed against amyloid-A protein (AA) were examined by immunoelectron microscopy to identify amyloid-A (AA) amyloid fibrils in plastic-embedded renal tissue of five patients and two controls. Two monoclonal antibodies (mc1, mc20) specifically labeled these amyloid deposits; two additional ones (mc4, mc13) bound with an intermediate rabbit anti-mouse IgG antiserum. These monoclonal anti-AA antibodies clearly separate amyloid fibrils from morphologically similar fibrils in the vicinity. Employing varying embedding media, fixation techniques, as well as etching and staining protocols, we adapted this method for the immunoelectron microscopic identification of AA-type amyloid fibrils and for the antigenic diagnosis of AA-type amyloid on routinely processed ultrathin sections.

Amyloidosis↗
PubMed1998

Time domain method to identify simultaneously parameters of the windkessel model applied to the pulmonary circulation.

Lumped models are frequently used to provide a satisfactory description of the hemodynamic properties of the pulmonary vasculature. The purpose of this study is to describe a method to identify simultaneously the parameters values of windkessel models components. The following equation was used to obtain R1 (characteristic resistance), R2 (peripheral resistance), C (total compliance) and L (inertance): [formula: see text] where ki are the following functions of L, R1, R2 and C: [formula: see text] To assess the accuracy of the method, estimates of R1, R2, and C were compared to characteristic impedance Rc, vascular resistance PVR and pulmonary arterial compliance Cd respectively computed from referenced methods. Comparison between R1 and Rc, PVR and R1 + R2, C and Cd were obtained in 5 anaesthetised pigs during basal conditions and after endotoxin-shock. The results indicate that in both conditions, comparisons evidenced highly significant correlations between values computed by the different approaches (p < 0.0001). Although our method yielded to consistently lower values than values provided by referenced methods, the results were concordant with respect to the expected response of pulmonary vasculature to endotoxin insult. We conclude that our method of identification is suitable for the assessment of lumped parameters windkessel model estimates. The main interest is that actual resistance and compliance values can be obtained easily and simultaneously by a global method approach.

Animals↗
PubMedDate not supplied

[Distribution of D1S80 alleles in a random sample of the population of the Russian Federation].

The distribution of alleles of chromosomal locus D1S80 was studied within a random selection of population of the Russian Federation. Typing was made for 255 persons who were not blood relatives and who lived in 56 Russia's regions. A correlation was found between the observed frequencies of genotypes and those theoretically expected and estimated on the basis of the hypothesis of Hardy-Weinberg equilibrium. The main population characteristics of locus D1S80, i.e. probability of an incidental coincidence of a genotype, discriminating potential, polymorphism factor, potential excluding cases of incorrectly named parents and mean value of paternity index, were estimated to evaluate the efficiency of the locus as a molecular-genetic marker in solving the identification tasks applicable to Russia's population. The obtained descriptive data on the distribution of alleles of the studied locus in Russia's population can be used to determine the needed estimated parameters in interpreting the results of forensic molecular-genetic identification examinations.

Alleles↗
PubMed2003

The power and promise of population genomics: from genotyping to genome typing.

Population genomics has the potential to improve studies of evolutionary genetics, molecular ecology and conservation biology, by facilitating the identification of adaptive molecular variation and by improving the estimation of important parameters such as population size, migration rates and phylogenetic relationships. There has been much excitement in the recent literature about the identification of adaptive molecular variation using the population-genomic approach. However, the most useful contribution of the genomics model to population genetics will be improving inferences about population demography and evolutionary history.

Genetics, Population↗
PubMed1989

[Echocardiographic diagnosis of acute graft rejection in heart transplant patients under cyclosporin therapy].

Though endomyocardial biopsy has remained the gold standard for diagnosing acute cardiac rejection (AR), this invasive method does not provide adequate means for close monitoring of the rejection process. In order to assess the usefulness of M-Mode- and two-dimensional (2D) echocardiography for the noninvasive diagnosis of AR in heart transplant recipients on cyclosporin, 45 patients (mean age 40.6 +/- 8.8 years, 19.9 +/- 14.4 months postoperatively) were evaluated prospectively. Mean observation time was 9.1 +/- 4.8 months. Echocardiographic examination techniques were strictly standardized; besides measurements of left (LV) and right ventricular (RV) diastolic wall thickness and of the isovolumic relaxation time, computerized frame-by-frame-analysis was applied to LV short axis cross sections for the determination of diastolic cavity cross-sectional area and extent and mean velocity of systolic and diastolic area change. To account for technical and biological variability, 95%-confidence limits were calculated for each parameter from two rejection-free examinations, allowing identification of significant changes during AR. In this study, 36 biopsy-proven AR occurred in 19 patients. Compared to control values, mean heart rate increased from 86.2 +/- 10.2 to 94.6 +/- 15.1 b/min (p less than 0.05), diastolic septal + posterior wall thickness from 21.2 +/- 4.1 to 24.9 +/- 6.2 mm (p less than 0.001) and RV free wall thickness from 6.3 +/- 1.1 to 8.9 +/- 1.8 mm (p less than 0.001). Isovolumic relaxation time decreased from 73.2 +/- 14.4 to 54.8 +/- 16.6 ms (p less than 0.001), diastolic cross-sectional area from 12.8 +/- 2.0 to 11.1 +/- 2.2 cm2 (p less than 0.05), relative area change from 65.8 +/- 9.8 to 49.1 +/- 14.4% (p less than 0.001) and systolic and diastolic area change velocities from 28.1 +/- 7.8 and 41.8 +/- 8.5 cm2/s to 18.9 +/- 5.6 and 28.6 +/- 9.2 cm2/s, respectively (p less than 0.001). Though significant changes occurred during AR, most measurements remained within the normal range. Thus, in individual patients, AR could only be suspected in comparison to the control measurements. None of the examined parameters allowed to establish the diagnosis of AR in all instances. However, when the measurements of all parameters were considered together, 35 of the 36 AR diagnosed by biopsy could also be identified by echocardiography, including all requiring intensified immunosuppressive therapy. Mild AR was not always detected, and the differential diagnosis between LV hypertrophy and AR required an endomyocardial biopsy in some instances.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed2005

Cross-spectral analysis of cardiovascular variables in supine diabetic patients.

Cardiovascular autonomic neuropathy in diabetes is associated with a high risk of mortality, which makes its early identification clinically important. An easy method for identification of subjects with autonomic dysfunction would be of clinical benefit. We evaluated the autonomic function in 28 diabetic patients and 21 control subjects recording 12 min time series of heart period (RR) and systolic arterial pressure (SAP, Finapres) during supine rest and 60 degrees head-up tilt. The power of the high (respiratory) and low (LF approximately 0.1 Hz) frequency oscillations was quantified by spectral analysis. The central frequency of the LF oscillations (LF_freq), phase shift, and the transfer function gain between RR interval and SAP fluctuations were provided by cross-spectral analysis, and measured at the point of maximal coherence. In the supine position 15 patients (LF-) displayed atypical LF variability with the LF_freq being shifted towards lower frequencies (about 0.06 Hz). They also showed larger phase angle, lower values or even absence of coherence and smaller transfer function gain between RR and SAP fluctuations. 13 patients (LF+) and the controls showed the LF_freq around 0.1 Hz, higher coherence and transfer function gain values. The orthostatic maneuver induced the expected changes in the spectral parameters (increase in the LF components of both RR and SAP and decrease in the HF variability of RR) into the LF+ patients and all the control subjects and abnormal response in the other 15 LF-patients. These findings indicate that diabetic subjects with uncharacteristic response to the orthostatic test present abnormal LF variability already in the supine position. Crossspectral parameters while supine may be used for the identification of these subjects.

Adult↗
PubMed2006

Correlates of Type 2 diabetes mellitus in children, adolescents and young adults in north India: a multisite collaborative case-control study.

AIMS: In this study we describe the clinical, anthropometric and biochemical characteristics of patients with early onset Type 2 diabetes mellitus (T2DM) (< 30 years of age) and compare them with healthy, non-diabetic individuals. METHODS: In this multisite collaborative study, 51 patients with T2DM (40 male, 11 female) and 69 non-diabetic individuals of similar age and gender distribution (controls) as the cases (46 male and 23 female) were investigated. The following parameters were measured; anthropometry [body mass index (BMI), waist circumference, waist-hip ratio (WHR) and skin-fold thickness at four sites], percentage body fat (%BF) and lipid profile. RESULTS: The mean (SD) age of diagnosis of T2DM was 21.4 (6.1) years. A significantly higher number of cases had a history of T2DM in first-degree relatives as compared with controls (82.3 vs. 23.2%, P < 0.001). The mean values and the prevalence of abnormal values of measures of generalized obesity (BMI and %BF) and abdominal obesity (waist circumference and WHR) were significantly higher in cases as compared with controls. Hypertriglyceridaemia [OR (95% CI): 4.6 (1.1-20.0)], high WHR [7.9 (2.5-24.4)] and family history of T2DM [7.3 (2.3-23.0)] were independently associated with T2DM. Age and gender adjusted odds ratios of T2DM were 23.3 (5.2-103.6), 37.7 (9.0-158.5) and 86.4 (17.0-438.5), respectively, with the following set of risk factors; hypertriglyceridaemia and high WHR, hypertriglyceridaemia and family history of T2DM, and high WHR and family history of T2DM. Finally, the presence of all three risk factors increased the odds of T2DM to 112.1 (10.8-1164.7). CONCLUSIONS: Early identification of the simple clinical, anthropometric and biochemical parameters which are strongly associated with early onset T2DM in young Asian Indians may be useful for primary prevention.

Adolescent↗
PubMedDate not supplied

Modes and classes of modes of action of physiologically active substances of receptor type under conditions of screening.

Questions of the identification of the type of pharmacological activity of physiologically active substances (PAS) with a receptor type of action under conditions of screening are examined. IN accordance with current concepts of the theory of the recognition of modes, the type of action of PAS was identified by establishing a set of criteria ("vectors of modes") characteristic of the effect of known substances and by selecting methods of comparing them with the vectors of the modes of the compounds being tested. Test parameters recorded by the the functional multiparametric method permitting identification of the type of the effects and an evaluation of their quantitative manifestations with the framework of a single experimental approach were used as the unknown set of criteria. The method of describing the relative change in the parameters from the dose as the vectors of action was used and the function of proximity (similarity).

Animals↗
PubMed2004

Treatment of relapsed/refractory multiple myeloma with thalidomide-based regimens: identification of prognostic factors.

We evaluated the predictive value of several parameters, including the International Staging System (ISS) for myeloma, in patients with advanced disease treated with thalidomide-based regimens (TBR). We analyzed 119 patients, from 3 phase II studies. Patients with pretreatment beta2 microglobulin<3.5 mg/l and albumin 3.5 g/dl were scored ISS stage 1, patients with beta2 microglobulin<3.5 mg/l and albumin<3.5 g/dl or beta2 microglobulin 3.5-5.5 mg/l regardless of albumin levels were scored ISS stage 2, patients with beta2 microglobulin>5.5 mg/l ISS stage 3. ISS stage was 1, 2 and 3 in 45, 32 and 23% of patients respectively. Seventy-four patients (62%) achieved at least partial response. Median progression-free and overall survival were 8 months and 19.5 months respectively. ISS stage, serum LDH and performance status were independent predictive factors for survival. Based on these 3 variables a scoring system was developed with survival times of 38.1, 28.8 and 5.8 months for scores 0, 1 and 2 respectively. The ISS staging system was highly predictive for overall survival of patients with advanced myeloma treated with TBR. With the addition of performance status and serum LDH, a simple scoring system was developed which may help select patients likely to benefit from TBR.

Adult↗
PubMed1987

[Total parenteral nutrition and evaluation of nutritional status for the identification of patients at high risk].

The importance of using standardised parameters in pre-operative patient assessment is emphasised. This will identify nutritional deficiencies that are often unrecognised but play a decisive part in the patients' post-operative course. Above all such an assessment enables the clinician to administer the appropriate restorative treatment especially in the elderly patient.

Anthropometry↗
PubMed2003

Software for automated analysis of DNA fingerprinting gels.

Here we describe software tools for the automated detection of DNA restriction fragments resolved on agarose fingerprinting gels. We present a mathematical model for the location and shape of the restriction fragments as a function of fragment size, with model parameters determined empirically from "marker" lanes containing molecular size standards. Automated identification of restriction fragments involves several steps, including: image preprocessing, to put the data in a form consistent with a linear model; marker lane analysis, for determination of the model parameters; and data lane analysis, a procedure for detecting restriction fragment multiplets while simultaneously determining the amplitude curve that describes restriction fragment amplitude as a function of mobility. In validation experiments conducted on fingerprinted and sequenced Bacterial Artificial Chromosome (BAC) clones, sensitivity and specificity of restriction fragment identification exceeded 96% on restriction fragments ranging in size from 600 base pairs (bp) to 30,000 bp. The integrated suite of software tools, written in MATLAB and collectively called BandLeader, is in use at the BC Cancer Agency Genome Sciences Centre (GSC) and the Washington University Genome Sequencing Center, and has been provided to the Wellcome Trust Sanger Institute and the Whitehead Institute. Employed in a production mode at the GSC, BandLeader has been used to perform automated restriction fragment identification for more than 850,000 BAC clones for mouse, rat, bovine, and poplar fingerprint mapping projects.

Animals↗