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PubMed2005

Investigation of optimum energies for chest imaging using film-screen and computed radiography.

The purpose of the study was to compare the image quality of film-screen (FS) and computed radiography (CR) for adult chest examinations across a range of beam energies. A series of images of the CDRAD threshold contrast detail detection phantom were acquired for a range of tube potential and exposure levels with both CR and FS. The phantom was placed within 9 cm of Perspex to provide attenuation and realistic levels of scatter in the image. Hardcopy images of the phantom were scored from a masked light-box by two scorers. Threshold contrast indices were used to calculate a visibility index (VI). The relationships between dose and image quality for CR and for FS are fundamentally different. The improvements in VIs obtained using CR at 75 kVp and 90 kVp were found to be statistically significant compared with 125 kVp at matched effective dose levels. The relative performance of FS and CR varies as a function of energy owing to the different k-edges of each system. When changing from FS to CR, the use of lower tube potentials may allow image quality to be maintained whilst reducing effective dose. A tube voltage of 90 kVp is indicated by this work, but may require clinical verification.

Adult↗
PubMed1978

Verification of the optimal probabilistic basis of aural processing in pitch of complex tones.

Periodicity pitch for complex tones has been quantitatively accounted for by a two-stage process of Fourier-frequency analysis subject to random errors and significant nonlinearities, followed by an harmonic pattern recognizer that makes an optimum probabilistic estimate of the fundamental period of musical and speech sounds. The theory predicts that periodicity pitch is a multimodal probabilistic function of a given stimulus. A clear and empirically supported distinction is made between limitations on the pitch mechanism caused by the stochastic nature of aural frequency representation and by the deterministic resolution bandwidths of aural frequency analysis. This model was developed earlier [J. L. Goldstein, J. Acoust. Soc. Am 54, 1496-1516 (1973)] to account for probabilistic data on pitch errors [A. J. M. Houtsma and J. L. Goldstein, J. Acoust. Soc. Am. 51, 520 (1972)] measured with periodic stimuli comprising two successive harmonics. This paper presents new predictions by the theory that were calculated, with computer simulation where needed, for known probabilistic pitch data from stimuli comprising three to six successive harmonics. Predicted pitch errors increase with increasing errors in estimating the frequencies of stimulus harmonics and decrease as more harmonics are added to the stimulus. Optimum processor theory fully accounts for the multicomponent pitch data on the basis of similar errors in estimating component stimulus frequencies as reported earlier, thus providing further evidence for the optimum probabilistic basis of aural signal processing in pitch of complex tones.

Auditory Cortex↗
PubMed1984

Isolated rat brain capillaries possess intact, structurally complex, interendothelial tight junctions; freeze-fracture verification of tight junction integrity.

Populations of isolated brain capillaries have been proposed as useful models for in vitro studies of the blood-brain barrier. Preliminary investigations of barrier properties using such preparations of brain microvessels have suggested that the tight interendothelial junctions (zonulae occludentes) are intact and retain the impermeability to the protein tracer horseradish peroxidase, exhibited by them in vivo. The endothelial junctions of isolated capillaries are therefore assumed to be functionally "tight' in vitro. In order to determine the precise structural organization of these occluding junctions, including an estimate of their tightness (complexity), and to demonstrate a method for simple but precise assessment of junctional integrity, pellets of isolated rat brain capillaries were freeze-fractured and then replicated with platinum and carbon. The freeze-fracture images of interendothelial zonulae occludentes revealed complex arrays of intramembrane ridges and grooves characteristic of tight junctions. Longitudinal fractures of the cellular lining of capillaries exposed vast expanses of interendothelial plasma membrane interfaces and the junctional complexes situated between the cells. From such arrays, the elaborate and complex architecture of the zonulae occludentes could be readily appreciated. Situated on the PF fracture faces are 6-8 parallel ridges which display a high degree of anastomosing between adjacent strands. The EF fracture face contains grooves complementary to the PF face ridges. The zonulae occludentes of these capillary endothelial cells are similar in complexity to those reported in the literature for reptilian brain capillaries and therefore can be presumed "very tight'. This study demonstrates that freeze-fracture of pellets of brain capillaries alleviates sampling problems inherent in whole tissue preparations and, in addition, demonstrates the usefulness of freeze-fracture as a tool to monitor junction structure during in vitro investigation of the blood-brain barrier.

Animals↗
PubMed2000

[Surgical treatment of bleeding duodenal ulcer in elderly and senile patients with intraoperative verification of the diagnosis].

The method of duodenotomy performance for duodenal ulcer with hemorrhage was proposed. Duodenum was dissected longitudinally across the ampulla lower edge going all over medial edge of pars descendens, permitting not only doing the revision but revealing the hemorrhage source, securing homeostasis. The rules of local hemostasis performance were elaborated. Application of the above mentioned access prevents damage of nervi vagi duodenal anterior brunch, guaranteeing the duodenal motor-evacuation function preservation.

Aged↗
PubMed1991

Transesophageal echocardiography in patients with mechanical circulatory assistance.

Transesophageal echocardiography was used to assess myocardial function and to detect complications after mechanical circulatory support for 8 patients with cardiogenic shock. In 3 of 8 patients, serial transesophageal echocardiography documented improvement of systolic ventricular function, and it was possible to wean these 3 patients from the ventricular assist device. In all patients, transesophageal echocardiography added clinically important information including the extent of left and right ventricular dysfunction (6 patients), presence of atrial or ventricular thrombus (5 patients), presence of pericardial effusion or clot (2 patients), and verification of the position of the intravascular device (1 patient). Thus, transesophageal echocardiography may provide clinically useful information regarding both the underlying cardiac disease and potential complications from the mechanical circulatory assistance.

Adult↗
PubMed2004

The impact of tumor motion upon CT image integrity and target delineation.

Accurate planning target volume delineation is vital to the success of conformal radiation techniques such as standard three-dimensional conformal radiotherapy and intensity modulated radiation therapy. With the exception of breath-hold schemes, all current approaches acquire images while the tumor is nonstationary and, as such, are subject to the presence of motion artifacts. In lung cancer sites where tumor mobility can be significant, the detrimental effect of these motion-induced distortions on image quality and subsequently target volume delineation cannot be ignored in the pursuit of improved treatment outcomes. To investigate the fundamental nature and functional dependence of computed tomography (CT) artifacts associated with lung tumor motion, and the implications for tumor delineation, a filtered backprojection algorithm was developed in MATLAB to generate transverse CT simulation images. In addition, a three-dimensional phantom capable of mimicking the essential motions of lung tumors was constructed for experimental verification. Results show that the spatial extent of a mobile object is distorted from its true shape and location and does not accurately reflect the volume occupied during the extent of motion captured. The presence of motion also negatively impacts image intensity (density) integrity rendering accurate volume delineation highly problematic and calling into question the use of such data in CT-based heterogeneity correction algorithms for dosimetric calculation.

Algorithms↗
PubMed2006

Characterization and expression profile of CMTM3/CKLFSF3.

CMTM/CKLFSF is a novel family of proteins linking chemokines and TM4SF. In humans, these proteins are encoded by nine genes, CKLF and CMTM1-8/CKLFSF1-8. Here we report the characteristics and expression profile of CMTM3/CKLFSF3. Human CMTM3/CKLFSF3 has a high sequence identity among various species and similar characteristics as its mouse and rat homologues. Established by results both of RT-PCR and Quantitative Real-time PCR, the gene is highly transcribed in testis, leukocytes and spleen. For further verification, we generated a polyclonal antibody against human CMTM3/CKLFSF3 and found that the protein is highly expressed in the testis and some cells of PBMCs. Therefore, CMTM3/CKLFSF3 is an evolutionarily conserved gene that may have important roles in the male reproductive system and immune system. Further studies are necessary to validate its functions in the two systems.

Amino Acid Sequence↗
PubMed2004

[Wilson's disease and secondary copper hemochromatoses in hematological practice].

AIM: To characterize clinical, diagnostic and therapeutic syndromes of copper overloading in patients with hepatic lesion in combination with hemopoietic disorder. MATERIAL AND METHODS: Treatment results and diagnostic findings are presented for patients with clinical picture of liver cirrhosis, cytopenia and copper overloading. The examination included standard clinical and specific tests, morphological investigation of the bone marrow, copper metabolism in dynamics. RESULTS: A case of a patient is reported in whom Wilson's disease presented in debut with a picture of decompensated liver cirrhosis and immune thrombocytopania complicated by recurrent hemorrhagic syndrome. D-penicillomine treatment initiated ex juvantibus allowed verification of the diagnosis of Wilson's disease and achievement of marked clinical response. In another case laboratory signs of copper overloading were revealed in a patient with liver cirrhosis of viral etiology (HBsAg+) and deep cytopenia associated with uneffective hemopoiesis. Chelator therapy with D-penicillamine regressed cytopenic syndrome and improved functional capacity of the liver. CONCLUSION: Primary or secondary nature of copper overloading in patients with hepatic cirrhosis and critical cytopenia, pathogenesis of cytopenic syndrome, practical significance of copper hemochromatoses diagnosis are discussed.

Adult↗
PubMed2005

[Research advance on lake ecosystem dynamic models].

Starting with the role of system analysis in lake ecosystem research, this paper summarized the tentative procedures and softwares for studying the dynamics of lake ecosystem. There are several main stages in modeling the dynamics of lake ecosystem, namely, problems identification, mathematical formulation, computation, validation, sensitive analysis, calibration, and verification. In the modeling, selecting temporal and spatial scales is essential but complex. Since 1960s, a rapid progress has been made in modeling the dynamics of lake ecosystem, being developed from simple zero-dimension models to complex ecological-aquatic-hydrodynamic ones, among which, exergy was applied popularly as an objective function in modeling. In this paper, LakeWeb and LEEDS (Lake Eutrophication, Effect, Dose, and Sensitivity model) were analyzed as examples. In China, the development of lake ecosystem dynamic models could be traced back to 1980s, and most of them were focused on Lake Dianch, Lake Taihu, Lake Chaohu and Lake Donghu. Some softwares such as CE-QUAL-ICM, WASP, AQUATOX, PAMOLARE and CAEDYM were developed to simulate lake ecosystem dynamics, among which, CE-QUAL-ICM is more suitable for long and narrow water bodies. WASP consists of three parts, i. e., DYNHYD, EUTRO, and TOXI. AQUATOX is an ecological risk model, and the parameters are mainly calibrated in U. S. A, which has limited its further application in China. The software ECOPATH for simulating the energy flows in lakes was also described in this paper. There are still many shortages in the lake ecosystem dynamic models, e. g., the lack of sufficient monitoring data for validation, insufficient consideration of uncertainties and the role of bacteria, and inconsistent relationship with watershed changes. The uncertainties are mainly from the intrinsic uncertainties in aquatic ecosystem, in modeling, in parameters selection, and also in forecast and application. Setting up long-term monitoring and data sharing mechanism, using interpolation to make data more densely, introducing objective functions, dealing with uncertainties, and constructing watershed-lake ecosystem dynamic model could be the available ways for overcoming the shortages.

China↗
PubMed1995

The clinical significance of distortion in implant prosthodontics: is there such a thing as passive fit?

Passive fit of the implant prosthesis onto osseointegrated and functional fixtures intraorally is the "Holy Grail" of the discerning implant prosthodontist. There is growing recognition that the old and "tried" clinical procedures and laboratory fabrication methods transferred from traditional fixed and removable partial denture prosthodontics, fall short of achieving true passivity of fit. The stages of impression making, master cast, resin verification jig, waxing, investing, casting, veneer addition and finishing can all add to the final distortion of the prosthesis. Studies are emerging that report the possible distortion associated with each stage. Alternative strategies have also been suggested to by-pass these traditional stages, for example laser welding or the elimination of the impression using optical digitising and CAD-CAM. In the final analysis, totally "passive" fit is probably unachievable. The challenge is to determine a minimum level of distortion and associated stress that is acceptable and that confers adequate clinical longevity to the prosthesis. Developing clinical tests that measure stress levels intraorally as the prosthesis is fitted would be the ideal gold standard by which to judge the accuracy of fabrication procedures. This paper summarises and rationalises the growing body of literature dealing with accuracy of implant prosthodontic procedures.

Biomechanical Phenomena↗
PubMed2002

Corticosteroid therapy in pulmonary sarcoidosis: a systematic review.

CONTEXT: Corticosteroids are used in pulmonary sarcoidosis to reduce symptoms and minimize long-term damage. Spontaneous recovery is a common feature. Both the decision to initiate therapy and the treatment response may be influenced by disease severity, so trials need to use a randomized controlled design. OBJECTIVE: To assess the effect of oral and inhaled corticosteroids on chest radiograph results, symptoms, pulmonary function, and long-term outcome in pulmonary sarcoidosis. DATA SOURCES: MEDLINE, EMBASE, CINAHL, and the Cochrane Controlled Trials Register were searched all years through December 2001. Bibliographies of review articles and retrieved articles were searched, and pharmaceutical companies and authors of identified trials were contacted for other studies. There was no language restriction. STUDY SELECTION: Trials were randomized and included a control group. Participants were adults with histologic evidence of pulmonary sarcoidosis. Treatments included the use of oral and inhaled corticosteroids for at least 8 weeks. The search identified 150 studies; 9 met the inclusion criteria, but only 8 provided usable data. DATA EXTRACTION: Two reviewers assessed trial quality using the Jadad score, which evaluates the quality of randomization, blinding, and reasons for withdrawal. Data were extracted and sent to primary authors for verification. DATA SYNTHESIS: In patients with stage 2 and 3 disease, oral corticosteroids improved findings on the chest radiograph after 6 to 24 months (Peto odds ratio, 2.54; 95% confidence interval [CI], 1.69-3.81; P<.001). Forced vital capacity improved with oral corticosteroids (weighted mean difference [WMD], 4.2% predicted; 95% CI, 0.4%-7.9% predicted) and diffusing capacity also improved (WMD, 5.7% predicted; 95% CI, 1.0%-10.5% predicted). In 2 small studies of inhaled corticosteroids, there was no effect on chest radiograph and inconsistent effects on lung function in one and only a small improvement in symptoms in the other. There were no data following corticosteroid withdrawal to assess any disease-modifying effect. CONCLUSIONS: Oral corticosteroids improved results on the chest radiograph following 6 to 24 months of treatment and produced a small improvement in vital capacity and diffusing capacity. Trials of inhaled corticosteroids were small and results too inconsistent to make firm conclusions concerning their efficacy. There are no data to suggest that corticosteroid therapy alters long-term disease progression.

Administration, Inhalation↗
PubMed2004

A novel and conserved pocket of human kappa-Fab fragments: design, synthesis, and verification of directed affinity ligands.

Antibodies of type IgG may be divided into two classes, called lambda or kappa, depending on the type of light chain. We have identified a conserved pocket between the two domains CH1 and CL of human IgG kappa-Fab, which is not present in the lambda type. This pocket was used as a target docking site with the purpose of exploring the possibilities of designing affinity ligands that could function as such even after immobilization to gel. The idea of the design arose mainly from the results of the saturated transfer difference (STD-NMR) screening of 46 compounds identified by means of virtual docking of 60 K diverse compounds from the Available Chemicals Directory (ACD). Surface plasmon resonance (SPR) was used as an alternative method to monitor binding in solution. A total of 24 compounds belonging to a directed library were designed, synthesized, and screened in solution. They consist essentially of an amino acid condensed to a N,N'-methylated phenyl urea. STD-NMR results suggest that a small hydrophobic side chain in the condensed amino acid promotes binding, whereas a hydroxyl-group-containing side chain implies absence of STD-NMR signals. Three compounds of the directed library were immobilized and evaluated as chromatographic probes. In one case, using D-Pro as the condensed amino acid, columns packed with ligand-coupled Sepharose (Amersham Biosciences) retained two different monoclonal samples of kappa-Fab fragments with different variable regions, whereas a sample of monoclonal lambda-Fab fragments was not retained under similar chromatographic conditions.

Antibodies, Monoclonal↗
PubMed2003

Absence of adverse effects of severe hypoglycemia on cognitive function in school-aged children with diabetes over 18 months.

OBJECTIVE: Some children with type 1 diabetes may be at risk of cognitive impairments, but mechanisms of this effect have not been confirmed. The objective of this study was to determine whether severe hypoglycemia (SH) in children with type 1 diabetes is associated with cognitive decline over 18 months. RESEARCH DESIGN AND METHODS: A sample of 142 6- to 15-year-old children with type 1 diabetes (mean age 11.6 +/- 2.7 years) enrolled in a trial of intensive therapy (IT) or usual care (UC) were tested with the Das-Naglieri Cognitive Assessment System at baseline and after 9 and 18 months. Episodes of SH were recorded by parents and reported promptly for verification by study nurses. HbA(1c) was measured quarterly. RESULTS: Over 18 months, 58 of 142 patients (41%) experienced 111 SH episodes, with a RR of SH of 1.12 for IT over UC. Neither occurrence nor frequency of SH was associated with decline in full-scale intelligence quotient (IQ), standard scores for planning, attention, simultaneous processing, or successive processing, or scaled scores on any of eight subtests. The same findings emerged when only patients who had experienced hypoglycemic seizures or coma were included in the SH group for analyses. These effects persisted when the child's age, sex, type 1 diabetes duration, and age at diagnosis were controlled statistically. HbA(1c) during the trial was not associated with cognitive changes. CONCLUSIONS: SH did not induce adverse changes in the measures of cognitive function administered to 6- to 15-year-old children with type 1 diabetes in this study. Although SH should be avoided in all children with diabetes, these episodes did not have adverse effects on cognition in this age-group over 18 months.

Adolescent↗
PubMedDate not supplied

Expression and function of Fc gamma RII on human natural killer cells.

In this report, we present data on the expression and function of Fc gamma RII (CD32) by natural killer (NK) cells. Highly enriched NK cell populations were isolated from peripheral blood lymphocytes by negative selection and consisted of > or = 95% CD3-/CD56+ cells. Flow cytometric analyses with anti-CD32 monoclonal antibodies (mAbs) demonstrated that a small proportion of NK cells were recognized by mAbs IV.3 and 41H16. Two-color flow cytometric analysis indicated coexpression of the epitope on NK cells recognized by both these mAbs. Verification of expression of CD32 on NK cells was obtained by demonstrating coexpression of CD32 on either CD16+ or CD56+ cells. The CD32+/CD16+ and CD32+/CD56+ cells represented approximately 7 and 3% of the total, respectively. CD32 transcripts were identified from highly purified NK cells using reverse transcription-polymerase chain reaction with CD32-specific primers, followed by Southern blotting. Enhanced chemiluminescence-Western blot (ECL-WB) analysis of lysates of purified NK cells indicated that mAb IV.3 recognized a molecule of approximately 40 kD. The Fc gamma RII on NK cells was able to transduce intracellular signals in several types of assay. Cross-linking of anti-CD32 resulted in a mobilization of intracellular Ca2+, although to a lesser extent than that induced by cross-linking CD16. Both mAbs IV.3 and 41H16 were found to be capable of inducing reverse antibody-dependent cellular cytotoxicity against FcR+ target cells (e.g. P815). These data represent the first direct description of the expression and function of Fc gamma RII on human NK cells.

Antibodies, Monoclonal↗
PubMed1995

Methodological and statistical problems in the construction of composite measurement scales: a survey of six medical and epidemiological journals.

Composite measurement scales (CMS) are increasingly used in medicine to measure complex phenomena or concepts such as disease risk and severity, physical and psychological functioning and quality of life. To investigate the methodology currently used in the construction of CMS, we examined 46 studies recently published in six major medical and epidemiological journals. Important measurement properties such as measurement level, content and construct validity and reliability are often neglected. Statistical methods, particularly multivariate methods are frequently misused; verifications of model relevance and assumptions, and cross-validations to avoid overfitting are seldom performed. We propose recommendations for the construction and the presentation of CMS, to help authors and investigators to report and choose, respectively, measurement instruments for a complex phenomenon.

Data Collection↗
PubMed2004

Functional prediction of a T-DNA tagged gene of Arabidopsis thaliana by in silico analysis.

We have employed a gene-knockout approach using T-DNA tagging and in vivo gene fusion in Arabidopsis thaliana for identification and isolation of specific plant genes. Screening of about 3,000 T-DNA tagged lines resulted in identification of a mutant line (no. 197) exhibiting a significant delay in flowering. From this line a 600-bp plant DNA fragment downstream of the left T-DNA junction was cloned by inverse PCR. BLAST searching in the A. thaliana genomic database indicated a putative gene, frf (flowering regulating factor), with unknown function downstream of the T-DNA insert. Bioinformatic tools were used to predict possible protein structure and function. The protein structure predicted by fold recognition indicates that frf is a transcriptional regulator, a ligand-binding receptor responsive to steroids and hormones. Analyzing the predicted results and the phenotype of the T-DNA tagged plant we hypothesized that FRF might be involved in hormone response in A. thaliana. For verification of this hypothesis we exposed the plants of line no. 197 to gibberellic acid (GA3), a potential growth regulator in higher plants. This treatment resulted in an earlier onset of flowering, almost similar to that in wild type control plants.

Amino Acid Sequence↗
PubMed2005

Probing the mechanism of sulfoxide-catalyzed hemiacetal activation in dehydrative glycosylation.

The concept of sulfoxide-covalent catalysis has been established in the context of a versatile hemiacetal hydroxyl activation/substitution reaction for the formation of anomeric linkages. Mechanistic studies focused on the hemiacetal activation process show that this transformation proceeds in the presence of a sulfonic anhydride and an acid scavenger through the intermediacy of a glycosyl sulfonate species (10), which serves as a resting state prior to the addition of an external nucleophile and subsequent glycosidic bond formation. Successful determination of the proportion of (18)O incorporation in 10 as a function of its formation, via the technique of dynamic monitoring of (13)C-(16/18)O isotopic chemical shift perturbations, provides strong evidence that hemiacetal activation proceeds through initial nucleophilic addition of the hemiacetal hydroxyl to the S(IV)-center of putative sulfonium sulfonate 6. Further confirmation was obtained through the independent synthesis, structure verification, and (1)H NMR detection of glycosyl oxosulfonium 11 during the sulfoxide-catalyzed conversion of hemiacetal 3 to glycosyl sulfonate 10.

Acetals↗
PubMed2004

Multi-modality tissue-mimicking phantom for thermal therapy.

A tissue-mimicking phantom material has been developed for use with thermal therapy devices and techniques. This material has magnetic resonance properties (primarily T2) which change drastically upon thermal coagulation, enabling its use for device characterization and treatment verification using simple T2-weighted imaging techniques. The coagulation temperature of the phantom can be changed from 50-60 degrees C by adjusting the pH from 4.3 to 4.7. The energy absorption properties can be adjusted to match the acoustical and optical properties of tissues. T2 relaxation measurements are provided as a function of temperature, along with T2-weighted MR images to illustrate the visualization of heating patterns. A complete recipe for fabricating phantoms is provided.

Acrylic Resins↗