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[Optimization and diagnostic accuracy of computerized tomography with tridimensional spiral technique in the study of craniostenosis].

INTRODUCTION: Conventional Computed Tomography (CT) with three-dimensional (3D) reconstructions is considered the most complete and accurate imaging modality to diagnose craniosynostosis. However, the introduction of Spiral CT (SCT) opened new possibilities for 3D studies of the skull in pediatric patients with craniosynostosis. The purpose of our study is two fold: first, to optimize the scanning and imaging parameters to obtain diagnostic images in a single spiral scan; second, to assess the diagnostic accuracy of such images in the identification of normal and abnormal cranial vault sutures. MATERIAL AND METHODS: Seventy-eight pediatric patients (age range: 1-35 months; mean: 11.8 months) with craniosynostosis were submitted to SCT of the head. The images were acquired with the following parameters: 3- and 5-mm nominal slice thickness, 5-6 mm/s table feed (pitch 1-2), 165 mAs and 120 kV. Two different algorithms and increases were used for image reconstructions. A first set of images was reconstructed with 2-mm increases and a soft tissue algorithm: these images were used for brain studies and for 3D reconstructions. A second set of slices was reconstructed with 5-mm increases and a bone algorithm to visualize the sutures of the axial plane. The 3D images were processed with the Shaded Surface Display software with threshold values ranging 120-150 HU. All images were acquired with a single spiral scan lasting less than 30 seconds. Two blinded radiologists analyzed the 3D and the planar images independently to evaluate the course and depth of each cranial suture. The sensitivity, specificity and diagnostic accuracy of both 3D and planar SCT images were evaluated. The frequency of artifacts (the Lego effect, boiled egg, pseudoforamina, movement, and chainsaw artifacts) and their influence on the final diagnosis were studied on 3D SCT images. RESULTS: The diagnostic accuracy rates of 3D SCT images, by suture, were: sagittal 90.7%, metopic 100%, left lamboid 90.9%, right lamboid 93.9%, left coronal 85.7%, right coronal 91.1%. The diagnostic accuracy rates of the axial images, by suture, were: sagittal 90.7%, metopic 95.5%, left lamboid 86.4%, right lamboid 90.9%, left coronal 83.7%, right coronal 91.1%. The interobserver agreement on 3D images was: sagittal 91.1%, metopic 100%, left lamboid 88.9%, right lamboid 91.1%, left coronal 88.9%, right coronal 84.4%. The Lego effect artifact was the most frequent one (82%) and affected image evaluation in 6.3% of cases. CONCLUSIONS: Our results prove that 3D SCT is a very accurate technique for identifying normal and abnormal sutures and presents many advantages over conventional 3D CT in the examination of pediatric patients with craniosynostosis. The quality of 3D SCT images was adequate and the artifacts did not affect the final diagnostic yield significantly.

Child, Preschool↗
PubMed2005

Identification of transient renal autoregulatory mechanisms using time-frequency spectral techniques.

Identification of the two principal mediators of renal autoregulation from time-series data is difficult, as both the tubuloglomerular feedback (TGF) and myogenic (MYO) mechanisms interact and share a common effector, the afferent arteriole. Moreover, although both mechanisms can exhibit oscillations in well-characterized frequency bands, these systems often operate in nonoscillatory states not detectable by frequency-domain analysis. To overcome these difficulties, we have developed a new approach to the characterization of the TGF and MYO systems. A laser Doppler probe is used to measure fluctuations in local cortical blood flow (CBF) in response to spontaneous changes in blood pressure (BP) and to large imposed perturbations in BP, which elicit strong, simultaneous, transient, oscillatory blood flow responses. These transient responses are identified by high-resolution time-frequency spectral analysis of the time-series data. In this report, we compare four different time-frequency spectral techniques (the short-time Fourier transform (STFT), smoothed pseudo Wigner-Ville, and two recently developed methods: the Hilbert-Huang transform and time varying optimal parameter search (TVOPS)) to determine which of these four methods is best suited for the identification of transient oscillations in renal autoregulatory mechanisms. We found that TVOPS consistently provided the best performance in both simulation examples and identification of the two autoregulatory mechanisms in actual data. While the STFT suffers in time and frequency resolution as compared to the other three methods, it was able to identify the two autoregulatory mechanisms. Taken together, our experience suggests a two level approach to the analysis of renal blood flow (RBF) data: STFT to obtain a low-resolution time-frequency spectrogram, followed by the use of a higher resolution technique, such as the TVOPS, if even higher time-frequency resolution of the transient responses is required.

Algorithms↗
PubMed1989

[Electrocardiographic findings in a school-age population using a computerized system: calculation of standard norms for heart rate and PR, QRS, and QT intervals].

We evaluated some ECG parameters (HR, P-R, Q-R-S, Q-T) in a healthy school-age population. One-thousand-eight-hundred and ninety children ranging in age from 5 to 12 coming from different zones of the city of Naples were studied. On physical examination all subjects were free from cardiac disease. A computerized ECG (Muse 12SL System Marquette) was performed on every subject. One-hundred and seventy-four of the 1890 children were excluded from statistical analysis because of ectopic rhythm (junctional rhythm or wandering pacemaker) or poor quality of the recording. Of the 1716 children included in the study, 837 were male and 879 were female. The computerized ECG 12SL System Marquette registers an ECG record consisting of all 12 classical ECG leads acquired simultaneously over a 10 second period. Each individual complex can be analyzed in all leads by the computer. An interpretation using this extended record, along with an ECG record of conventional length, is presented to the physician for review. The first step in computerized ECG analysis is Q-R-S identification, then P wave identification, beat classification, rhythm analysis, morphology analysis, complex alignment and computation of median complex. All parameters were divided for sex and age and gathered into tables. The variability of P-R, Q-R-S, Q-T versus HR were also evaluated. The following conclusions were drawn: 1) Sex is a very important variable in the parameters examined. Males have a much slower HR, greater Q-R-S duration, and longer Q-T interval when compared to females. 2) As age increases, HR slowly decreases, while P-R, Q-R-S and Q-T intervals increase.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1980

Factors affecting the differential counting of human lymphocyte subpopulations in blood smears.

We have previously used the antibody-mediated binding of bacteria to identify Ig-bearing cells and the natural binding of bacteria to identify several lymphocyte subpopulations. By using bacteria this identification can be carried out in conventional blood smears since bacteria are small and easily distinguished from all blood elements. To develop a standardized method for identification of lymphocyte subpopulations that may become useful in clinical laboratories, we investigated here several parameters that might affect the safety and accuracy of the test, and that might simplify the procedure. We found that: (1) the rosettes formed between bacteria and lymphocytes cannot be disrupted by vigorous handling; (2) the ability fo form rosettes is a stable property of the bacterial strains; (3) for optimal results the blood sample must not be stored for more than 4 hr at 25 degrees C and the entire procedure must be performed in medium supplemented with 6% bovine serum albumin; (4) a large excess of anti-Ig antibody is required for the optimal coating of bacteria to detect Ig-bearing cells; (5) both the antibody-coated bacteria and formaldehyde-fixed bacteria can be stored at 4 degrees C or at -20 degrees C for at least 6 months; (6) the buffy coat from the blood sample can be used instead of the whole blood to reduce the time required for reading the smears; and (7) some of the pathogenic bacteria can be killed by autoclaving without modifying their binding properties. A complete and simple method which uses the bacterial adherence for the identification of lymphocyte subpopulations in blood smears is presented.

Antibodies, Anti-Idiotypic↗
PubMed2004

Two-dimensional electrophoresis for the isolation of integral membrane proteins and mass spectrometric identification.

Acrylamide concentration, urea content, and the trailing ion used for sodium dodecyl sulfate (SDS)-gels modify electrophoretic protein mobilities in a protein-dependent way. Varying these parameters we coupled two SDS-gels to a two-dimensional (2-D) electrophoresis system. Protein spots in 2-D gels are dispersed around a diagonal. Hydrophobic proteins are well separated from water-soluble proteins which is the essential advantage of the novel technique. Mass spectrometric identification of previously unaccessible hydrophobic proteins is now possible.

Animals↗
PubMed2006

Reliability of conformational measurements in the horse using a three-dimensional motion analysis system.

REASONS FOR PERFORMING STUDY: The importance of a reliable method for conformation studies is generally acknowledged, but there are only limited data on the accuracy and precision of current assessment methods. OBJECTIVES: To assess (1) the accuracy and repeatability of marker placement, (2) influence of stance of the horse on conformational parameters, (3) practicality of a computerised motion analysis system and (4) to compare the computerised motion analysis system to photographic systems of assessment. METHODS: Twenty-eight reflective markers placed over anatomical landmarks were located in 3D using a computerised motion analysis system and their coordinates used to calculate segment lengths and joint angles. Four experiments, involving a cadaver study, a series of repeated measures on a single Thoroughbred and repeat measurements on 108 racehorses were performed. RESULTS: Identification of anatomical landmarks was found to introduce the biggest variation in the measurements for proximal conformation parameters with the interoperator being larger than intraoperator variation. Length measurements were least influenced by stance, with distal interphalangeal and metacarpo/metatarsophalangeal joint angles being the most variable. In some measurements, the variation between stances within a horse proved to be almost as large as between horses, rendering these parameters less useful as predictors of performance or orthopaedic health. CONCLUSIONS: A computerised motion analysis system allows 3D assessment of conformation with high accuracy and precision. It eliminates 3 major sources of error associated with photography-based methods and increases accuracy of conformational assessment by allowing repeat measurements in a relatively short period. POTENTIAL RELEVANCE: Studies on conformation should be viewed in the light of the limitations of the measurement technique used. The presented method maximises accuracy and precision and is a valuable basis for future studies investigating the effect of conformation on performance or orthopaedic health.

Animals↗
PubMed1985

The use of multidimensional perceptual models in the selection of sonar echo features.

The development of an accurate and efficient sonar-target classification system depends upon the identification of a set of signal features which may be used to discriminate important classes of signals. Feature selection can be facilitated through the identification of perceptual features used by human listeners in discriminating relevant sonar echoes. This study was conducted to establish a more reliable means of identifying perceptual features in terms of physical signal parameters as an initial step toward the development of an automatic sonar-target classification system. The results of an experiment involving eight subjects and six sonar echoes are presented. A model of the perceptual structure of these echoes was derived from subject similarity judgments using a multidimensional scaling (MDS) technique. It was found that three perceptual features accounted for the similarity judgments made by the human listeners. Echoes modified along candidate physical dimensions were employed to aid in the identification of perceptual dimensions in terms of physical signal parameters. The three perceptual features could be associated with signal parameters involving the amplitude envelope of the echoes.

Auditory Perception↗
PubMed2006

Matrix effects on accurate mass measurements of low-molecular weight compounds using liquid chromatography-electrospray-quadrupole time-of-flight mass spectrometry.

Liquid chromatography (LC) with high-resolution mass spectrometry (HRMS) represents a powerful technique for the identification and/or confirmation of small molecules, i.e. drugs, metabolites or contaminants, in different matrices. However, reliability of analyte identification by HRMS is being challenged by the uncertainty that affects the exact mass measurement. This parameter, characterized by accuracy and precision, is influenced by sample matrix and interferent compounds so that questions about how to develop and validate reliable LC-HRMS-based methods are being raised. Experimental approaches for studying the effects of various key factors influencing mass accuracy on low-molecular weight compounds (MW < 150 Da) when using a quadrupole-time-of-flight (QTOF) mass analyzer were described. Biogenic amines in human plasma were considered for the purpose and the effects of peak shape, ion abundance, resolution and data processing on accurate mass measurements of the analytes were evaluated. In addition, the influence of the matrix on the uncertainty associated with their identification and quantitation is discussed. A critical evaluation on the calculation of the limits of detection was carried out, considering the uncertainty associated with exact mass measurement of HRMS-based methods. The minimum concentration level of the analytes that was able to provide a statistical error lower than 5 ppm in terms of precision was 10 times higher than those calculated with S/N = 3, thus suggesting the importance of considering both components of exact mass measurement uncertainty in the evaluation of the limit of detection.

Calibration↗
PubMed1999

In vitro osteoblastic differentiation of human bone marrow cells in the presence of metal ions.

For periods up to 21 days human bone marrow was cultured in control conditions that favor the proliferation and differentiation of osteoblastic cells. The effect of AISI 316L corrosion products and the corresponding major separate metal ions (Fe, Cr, and Ni) were studied in three different phases of the culture period in order to investigate the effects of metal ions in cell populations representative of osteoblastic cells in different stages of differentiation. Toxicity consequences of the presence of metal ions in bone marrow cultures were evaluated by biochemical parameters (enzymatic reduction of MTT, alkaline phosphatase activity, and total protein content), histochemical assays (identification of ALP-positive cells and Ca and phosphates deposits), and observation of the cultures by light and scanning electron microscopy. Culture media were analyzed for total and ionized Ca and P and also for metal ions (Fe, Cr, and Ni). The presence of AISI 316L corrosion products and Ni salt in bone marrow cultures during the first and second weeks of culture significantly disturbs the normal behavior of these cultures, interfering in the lag phase and exponential phase of cell growth and ALP expression. However, the presence of these species during the third week of culture, when expression of osteoblastic functions occurs (mineralization process), did not result in any detectable effect. Fe salt also disturbs the behavior of bone marrow cell cultures when present during the lag phase and proliferation phase, and a somewhat compromised response between the normal pattern (control cultures) and intense inhibition (AISI 316L corrosion products and Ni salt-added cultures) was observed. Fe did not affect the progression of the mineralization phase. Osteogenic cultures exposed to Cr salt (Cr3+) presented a pattern similar to the controls, indicating that this element does not interfere, in the concentration studied, in the osteoblastic differentiation of bone marrow cells. Quantification of metal ions in the culture media showed that Cr (originated from AISI 316L corrosion products but from not Cr3+ salt) and Ni (originated from AISI 316L corrosion products and Ni salt) appear to be retained by the bone marrow cultures.

Alkaline Phosphatase↗
PubMed1992

Validation of PTSD measures for older combat veterans.

This study evaluated three nosologically similar older groups (Older PTSD, POW, and Older Psychiatric) and a group of Younger PTSD veterans from Vietnam. Group membership was derived from index admission diagnoses and clinical validation of status. Groups were compared on the MMPI, PTSD measures, background variables, health measures and an outcome measure. Results showed that the Older PTSD group is closer to the Younger PTSD group than to the other groups on the MMPI and PTSD measures and also that members of this group remain in the hospital longer than do members of the other older groups. Parameters of effective test classification showed the PTSD measures to be helpful in correct identification of this disorder for the older groups.

Age Factors↗
PubMed1995

Continuous and discontinuous domains: an algorithm for the automatic generation of reliable protein domain definitions.

An algorithm is presented for the fast and accurate definition of protein structural domains from coordinate data without prior knowledge of the number or type of domains. The algorithm explicitly locates domains that comprise one or two continuous segments of protein chain. Domains that include more than two segments are also located. The algorithm was applied to a nonredundant database of 230 protein structures and the results compared to domain definitions obtained from the literature, or by inspection of the coordinates on molecular graphics. For 70% of the proteins, the derived domains agree with the reference definitions, 18% show minor differences and only 12% (28 proteins) show very different definitions. Three screens were applied to identify the derived domains least likely to agree with the subjective definition set. These screens revealed a set of 173 proteins, 97% of which agree well with the subjective definitions. The algorithm represents a practical domain identification tool that can be run routinely on the entire structural database. Adjustment of parameters also allows smaller compact units to be identified in proteins.

Actins↗
PubMed2000

A New Method for the Characterization of Electrically Conducting Liquid Bridges.

An electrical conductance technique is employed in investigating the behavior of constant volume liquid bridges when their length is altered. The liquid bridges are edge-pinned between two vertical, identical rods with a variable separation distance. Rods of different radius, material, and edge geometry are examined as they play a role in the response of the system. It is shown that liquid bridge volume and rod radius are the parameters that mainly influence the conductance signal. A mathematical framework is developed for the identification of the geometrical characteristics of liquid bridges explicitly from conductance data. The role of gravity is discussed in both the experiments and the theoretical analysis. The theoretical predictions obtained show a close agreement with measurements. Copyright 2000 Academic Press.

Journal Article↗
PubMed2003

[Auditory brainstem responses evoked by direct mechanical stimulation of the ossicular chain. Objective preoperative testing of candidates for implantable hearing aids].

BACKGROUND AND OBJECTIVE: The function of several implantable hearing systems is based on the vibratory excitation of the ossicular chain. For preoperative testing, malleus vibration audiometry has been described [7]. In special cases, it could be desirable to perform objective testing before implantation. We therefore studied the auditory brainstem responses (ABR) evoked by vibratory stimulation of the ear drum. METHOD: The ABR evoked by vibratory and acoustical click stimulation were recorded in 20 subjects with normal hearing at four different stimulus intensities. For the vibratory stimulation (v-ABR), the transducer rod was brought into mechanical contact with the eardrum under microscopic control. This setup was further used for the determination of the individual subjective threshold. The v-ABR were compared to conventional ABR recordings. RESULTS: In all subjects, the v-ABR could clearly be identified. At high stimulus levels, the complete wave pattern was observed in 15 of 20 cases. There is no essential difference between v-ABR and conventional ABR with respect to the incidence and parameters of the potentials. At high stimulus levels, a pronounced stimulus artefact impedes the identification of wave I in some cases. Moreover, the quality of v-ABR is limited by the uncomfortable situation and incomplete relaxation of the subject. CONCLUSIONS: The measurement of vibratory evoked ABR is practicable without hazards for the patient and it yields reliable results. The hearing threshold for click stimuli can be determined from the incidence and amplitude of the responses. The loudness associated with the click stimuli can be estimated from the response latency. Therefore, the investigation of v-ABR not only gives evidence of the individual suitability for implantable hearing aids but its outcome may also be useful as an orientation for the postoperative fitting.

Acoustic Stimulation↗
PubMed2002

The rapid identification of organic colorants by UV/vis spectroscopy.

A rapid UV/vis spectroscopic method for the identification of organic colorants by the use of Gaussian analysis is presented. Sets of parameters are obtained for the screening with a low number of data. An optical distance using line positions and intensities is defined as a measure for the similarity of UV/vis spectra.

Journal Article↗
PubMed2004

Comparative analysis of nodal upstaging between colon and rectal cancers by sentinel lymph node mapping: a prospective trial.

PURPOSE: Sentinel lymph node mapping accurately predicts nodal status in > 90 percent of melanoma and breast and colorectal cancers. However, because of anatomic differences, sentinel lymph node mapping of rectal cancers has been considered inaccurate and difficult relative to colon. A prospective study was undertaken to identify differences in sentinel lymph node mapping between patients with colon cancer and those with rectal cancer. METHODS: At operation 1 to 3 ml of 1 percent isosulfan blue dye was injected subserosally around colon cancers. The first to fourth blue-staining nodes seen within ten minutes of injection were marked as sentinel lymph nodes. For cancer of the mid-rectum to low rectum, the dye was injected submucosally via rigid scope and spinal needle. The mesorectum was dissected ex vivo to identify blue nodes nearest the tumor as sentinel lymph nodes. Multilevel microsections of sentinel lymph nodes were stained with hematoxylin and eosin and immunostained for cytokeratin, and standard examination of the entire specimen was performed. RESULTS: There were 407 consecutive patients (336 with colon and 71 rectum). The sentinel lymph nodes were identified in 99.1 percent of colon and 91.5 percent of rectal patients (P < 0.0001). Skip metastases were found in 3.6 percent of colon vs. 2.8 percent of rectal patients (P = 0.16). Occult micrometastases were found in 13.4 percent of colon vs. 7.0 percent of rectal patients (P = 0.24). Except for success rates, no other parameters were statistically different between colon and rectum. Lower success in sentinel lymph node identification in rectal cancer may have been related to neoadjuvant chemoradiation received in all six of the patients with sentinel lymph node mapping failures. CONCLUSION: Despite higher success rates in sentinel lymph node identification for colon patients, sentinel lymph node mapping was highly successful (91.5 percent) in rectal patients. Nodal upstaging, skip metastases, and occult metastases were similar.

Aged↗
PubMed1979

Experience in treating two hundred and eighty-eight patients with endometrial carcinoma from 1968 to 1972.

The results in treatment of 288 patients with endometrial carcinoma (1968 to 1972) were compared to results achieved in a similar series of 236 patients (1962 to 1967) at The University of Alberta, Edmonton, Alberta, Canada. The overall 5 year survival rate for the 524 patients was 76.1% (75.4% when Stage 0 is excluded), with generally better results in the more recent series except in treating Stage II disease. The overall 5 year survival rate for Stage I disease in the more recent series was 89.1%. Parameters for assessing a prognosis and management plan are indicated, with emphasis on the identification of high-risk Stage I cases.

Adenocarcinoma↗
PubMed1980

Effect of stage of diestrus and number of cloprostenol (ICI 80, 996) injections on intervals to estrus, LH peak and ovulation in heifers.

Intervals to the onset of estrus, luteinizing hormone (LH) peak and ovulation were compared in diestrous heifers after each of two cloprostenol treatments. Diestrous heifers were grouped at the first treatment (T1) according to day of the cycle, with heifers on days 5 through 8 designated as early diestrus and heifers on days 9 through 17 designated as late diestrus. Cloprostenol treatment was repeated (T2) 11 days after T1, at which time heifers in both groups were at similar stages of the estrous cycle. Visual observation, identification of the preovulatory LH peak, and rectal palpation were utilized to estimate data parameters. Split-plot analysis of variance showed a significant treatment x group interaction (P < .05). Time from prostaglandin treatment to the onset of estrus was similar for the early diestrous group after T1 (x = 53.1 hours ) and the early and late diestrous groups after T2 (x = 49.4 hours and 45.4 hours respectively). This interval was longer (P < .05) for the late diestrous group after T1 (x = 60.8 hours ) than for either group after T2, but not different from that for the early diestrous group after T1. Serum progesterone concentrations were higher (P < .05) at the time of T1 in the late diestrous group (x = 5.8 ng/ml ) than in the early diestrous group (x = 3.0 ng/ml ) or in either group at the time of T2 (x = 2.8 and 3.2 ng/ml respectively). Over all heifers, the synchrony of the onset of estrus was more precise (P < .05) after T2 than T1. Intervals from the onset of estrus to ovulation were not affected by group or treatment (overall mean = 24.4 +/- 1.0 hours, n = 42). We conclude that different recommendations for appointment artificial insemination (AI) may be indicated depending on the number of prostaglandin injections which are used in a prostaglandin synchronization program prior to insemination.

Journal Article↗
PubMed1991

Hormonal modulation of plant growth: the role of auxin perception.

The organisation of growth and development in vascular plants appears to be highly adapted to meet the specific demands of a sessile, autotrophic habit. Many of the characteristic features of plant development are associated with the activities of five groups of phytohormones. Each of the phytohormones has the ability to influence fundamentally a remarkable variety of developmental and physiological processes. This ability has been widely documented but remains to be explained. Here we describe how recent breakthroughs in the analysis and understanding of eucaryotic signal transduction are being applied, in conjunction with technical advances in molecular genetics, to elucidate the molecular basis of the phytohormonal properties of auxin. Both auxin concentration, and the sensitivity of plant cells to this phytohormone have been implicated as important parameters in auxin action. We describe recent molecular biological approaches to assess the contribution made by each of these parameters. Emphasis is given to a description of recent genetic and biochemical progress towards identification of the molecular targets of the auxin signal and the molecular components involved in its subsequent transduction.

Endoplasmic Reticulum↗