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At least 1,135 records · Page 63Linked to original sources
PubMed2006

[Thromboembolic events in patients after a negative computed tomography pulmonary angiogram: A retrospective study of 165 patients].

OBJECTIVE: To determine the value of computed tomography (CT) angiography of the chest as a diagnostic test to exclude pulmonary embolism and to assess compliance with diagnostic protocols for thromboembolic disease. PATIENTS AND METHODS: We retrospectively studied patients who underwent CT angiography of the chest because of suspected pulmonary embolism in 2004. All the patients were followed for 3 months. The percentage of patients diagnosed with a thromboembolic event based on an objective test during the follow-up period was determined. We analyzed the percentage of patients with a negative CT angiogram on whom additional diagnostic tests (ultrasound of the lower limbs and/or ventilation-perfusion lung scintigraphy) were performed. RESULTS: One hundred sixty-five patients underwent CT angiography of the chest because of suspected pulmonary embolism in 2004. Four of the patients were excluded from the study because they were on chronic anticoagulation therapy and a further 2 were excluded because they had a life expectancy of under 3 months. Of the remaining 159 patients, 60 had CT angiograms that were interpreted as high probability for pulmonary embolism (prevalence of 38%). Thirty-nine of the 99 patients with a negative CT angiogram experienced an objectively confirmed thromboembolic event (63% sensitivity; 95% confidence interval, 53%-73%). Other diagnostic tests were not performed in 46% of the cases. CONCLUSIONS: In our setting, a negative single-detector helical CT angiogram was not sensitive enough to exclude the diagnosis of pulmonary embolism. Furthermore, compliance with internationally accepted diagnostic protocols was far from optimal.

Aged↗
PubMed2002

PCR detection of Tetramicra brevifilum (Microspora) infection in turbot (Scophthalmus maximus L.) musculature.

This study investigated the spatial distribution of Tetramicra brevifilum spores in the musculature of infected turbot Scophthalmus maximus, with the aim of identifying the most appropriate body locations for diagnostic assays. A PCR protocol optimized for the detection of T. brevifilum spores in turbot muscle is also described. In fish showing low- and moderate-intensity infection, the spatial distribution of spores was best fitted by a negative binomial distribution, indicating a clumped spatial pattern; the negative binomial coefficient k was lower for fish with low-intensity infection, indicating a more markedly clumped pattern in these fish. In fish with high-intensity infection, the spatial distribution of spores was best fitted by the Poisson distribution, indicating a random pattern. In both low- and moderate-intensity infection, spores were present at highest density in the musculature adjoining the dorsal fins. Samples for PCR were therefore obtained from this location. PCR amplification was of the small subunit ribosomal DNA (SSUrDNA), using a pair of species-specific primers that amplify the 1250 bp product. The PCR protocol developed showed better sensitivity than microscopical techniques (detection rate by microscopy 25%, versus 42% by PCR), suggesting that it may be useful for routine screening for Tetramicra brevifilum infection in cultured turbot.

Animals↗
PubMed2001

Effects of the ionic environment, charge, and particle surface chemistry for enhancing a latex homogeneous immunoassay of C-reactive protein.

The role of the solution environment for a light-scattering, latex-particle-enhanced, homogeneous immunoassay of C-reactive protein (CRP) has been investigated in order to assess and optimize the immunoagglutination response. Latex particles of 50-170-nm sizes were covalently coupled with an IgG polyclonal antibody and subjected to an extensive optimization regime. This consisted of conditions responsible, in different degrees, for the principal attractive/repulsive forces affecting both colloidal stability and the antibody/antigen interaction: particle size, antibody concentration, ionic strength and species, pH, and amino acid chemistry of the particle surface. Careful control of these parameters was found to be necessary to achieve the desired effects of balancing high colloidal stability in the absence of antigen but promoting a rapid, sensitive, and dose-dependent agglutination with pathological serum samples. In addition, the estimation of fundamental properties governing intermolecular interaction (i.e. the "Hamaker" constant and critical coagulation concentration) was attempted to order to investigate a simple, practical means of defining a colloidal/immunoassay system under "real conditions" as well as "real time". It is concluded that because each antibody system is unique, a similar optimization should be performed in diagnostic immunoassays of this type to maximize their clinical utility.

C-Reactive Protein↗
PubMed2004

Evaluation of 2-methacryloyloxyethyl phosphorylcholine polymeric nanoparticle for immunoassay of C-reactive protein detection.

To prepare novel 2-methacryloyloxyethyl phosphorylcholine (MPC)-polymeric nanoparticle (MPC-PNP), water-soluble amphiphilic phospholipid polymer, poly [MPC-co-n-butyl methacrylate (BMA)-co-p-nitrophenyloxycarbonyl poly(ethylene glycol) methacrylate (MEONP) (PMBN)], which has active ester groups for bioconjugation on the side chains, was synthesized. MPC-PNP was prepared by a solvent evaporation technique where the poly(l-lactic acid) was used as core and PMBN was applied as an emulsifier and a surface modifier under systematical design of well-arranged phospholipids polar groups in its surface. Characteristics for MPC-PNP were thoroughly investigated with dynamic light scattering, electrophoresis light scattering, X-ray photoelectron spectroscopy, and field emission scanning electron microscopy measurements. Through a protein adsorption test, the phosphorylcholine group on the surface of MPC-PNPs, which had their active ester groups substituted by glycine, were shown to suppress the nonspecific adsorption of bovine serum albumin. These particles were used for C-reactive protein (CRP) detection, where anti-CRP monoclonal antibodies were immobilized on the MPC-PNP using the active ester group, while the remaining active ester groups were thoroughly reacted with glycine. The detection limit about serum-free CRP in the calibration curve was shown to extend from 0.01 to 10 mg/dL when anti-CRP antibody immobilized MPC-PNP was used for serum-free CRP detection. This compares favorably with measurement using polystyrene nanoparticles that were shown to detect from 0.1 to 10 mg/dL by an immunoagglutination technique. Also, for the detection of CRP in serum, MPC-PNP was shown to give the same calibration curve explained by the efficient suppression of nonspecific binding. Furthermore, denaturation of immobilizing anti-CRP antibody on the MPC-PNP hardly occurred despite increasing the temperature. It is concluded that MPC-PNP is unique due to the design of its interfacial properties, also it will perform well in a diagnostic immunoassay because of its optimized material properties.

Adsorption↗
PubMed1999

Lymph node staging in clinically localized prostate cancer.

Pelvic lymph node involvement is an adverse prognostic factor in clinically localized prostate cancer, and a knowledge of nodal status is important for patient management. Whereas nodal disease has been widely regarded as incurable, evidence is now accumulating that some men with lymph node involvement may benefit from radical multimodality treatment approaches. Pelvic nodal status may be assessed by predictive nomograms, by imaging studies and by surgery. The pros and cons of each method are discussed together with the prospects for future development. Optimal strategies combining the different diagnostic approaches for the detection of lymph node metastases are considered in the context of the changing therapeutic implications of nodal disease.

Journal Article↗
PubMed1977

[An investigation into the effect of xerographic property on tomograms (author's transl)].

The properties of xerography as they affect tomography have been studied on phantoms. It was shown that, apart from better rendering of soft tissues, there is no fundamental difference. Section thickness and unwanted shadows are not influenced either way for optimal exposures. Significant improvement in diagnostic information can only be expected, if at all, under very special circumstances.

Models, Structural↗
PubMed2005

Standardization of cardiac markers.

Developing primary reference materials to standard cardiac biomarker assays, specifically cardiac troponin I (cTnI) and B-type natriuretic peptide (BNP), as well as develop quality specifications for immunoassays to optimize clinical use, whether for diagnostics or risk assessment, have been primary goals of the IFCC Committee on Standardization of Markers of Cardiac Damage (C-SMCD). The purpose of this paper is to review the current status of standardization issues for myoglobin, creatine kinase MB, cardiac troponin I and natriuretic peptides (BNP and NT-proBNP) and quality specifications for analytical immunoassays for the worldwide, consistent clinical utilization of these and future cardiac biomarkers.

Biomarkers↗
PubMed2006

In vitro evolution of single-chain antibodies using mRNA display.

Here we describe the application of the in vitro virus mRNA display method, which involves covalent linkage of an in vitro-synthesized antibody (phenotype) to its encoding mRNA (genotype) through puromycin, for in vitro evolution of single-chain Fv (scFv) antibody fragments. To establish the validity of this approach to directed antibody evolution, we used random mutagenesis by error-prone DNA shuffling and off-rate selection to improve the affinity of an anti-fluorescein scFv as a model system. After four rounds of selection of the library of mRNA-displayed scFv mutants, we obtained six different sequences encoding affinity-matured mutants with five consensus mutations. Kinetic analysis of the mutant scFvs revealed that the off-rates have been decreased by more than one order of magnitude and the dissociation constants were improved approximately 30-fold. The antigen-specificity was not improved by affinity maturation, but remained similar to that of the wild type. Although the five consensus mutations of the high-affinity mutants were scattered over the scFv sequence, analysis by site-directed mutagenesis demonstrated that the critical mutations for improving affinity were the two that lay within the complementarity determining regions (CDRs). Thus, mRNA display is expected to be useful for rapid artificial evolution of high-affinity diagnostic and therapeutic antibodies by optimizing their CDRs.

Antibody Affinity↗
PubMed1999

Reduced kidney transplant rejection rate and pharmacoeconomic advantage of mycophenolate mofetil.

BACKGROUND: Several multinational controlled clinical trials have shown that triple therapy immunosuppressive regimens which include mycophenolate mofetil (MMF), cyclosporin A (CSA) and steroids (S) are superior compared with conventional regimens which include azathioprine (AZA), CSA and S, mainly because MMF reduces the rate of acute rejection episodes in the first 6 months after kidney transplantation. Post-marketing studies are useful to evaluate the general applicability and costs of MMF-based immunosuppressive regimens. METHODS: Based on the excellent results of the published controlled clinical trials, we have changed the standard triple therapy immunosuppressive protocol (AZA+CSA+S) to an MMF-based regimen (MMF+CSA+S) at our centre. To analyse the impact of this change in regimen, we have monitored 6-month patient and graft survival, rejection rate, serum creatinine and CSA levels, as well as the costs of the immunosuppressive and anti-rejection treatments, in 40 consecutive renal transplant recipients (MMF group) and have compared the data with 40 consecutive patients transplanted immediately prior to the change in regimen (AZA group). RESULTS: Recipient and donor characteristics were similar in the AZA and MMF groups. Patient survival (37/40; 92.5% in the AZA group vs 38/40; 95% in the MMF group), graft survival (36/40 vs 36/40; both 90%) and serum creatinine (137+/-56 vs 139+/-44 micromol/l) after 6 months were not significantly different. However, the rate of acute rejection episodes (defined as a rise in creatinine without other obvious cause and treated at least with pulse steroids) was significantly reduced with MMF from 60 to 20% (P=0.0005). The resulting cost for rejection treatment was lowered 8-fold (from sFr. 2113 to 259 averaged per patient) and the number of transplant biopsies was lowered > 3-fold in the MMF group. The cost for the immunosuppressive therapy was increased 1.5-fold with MMF (from sFr. 5906 to 9231 per patient for the first 6 months). CONCLUSIONS: The change from AZA to MMF resulted in a significant reduction in early rejection episodes, resulting in fewer diagnostic procedures and rehospitalizations. The optimal long-term regimen in terms of patient and pharmacoeconomic benefits remains to be defined.

Adult↗
PubMed1994

Prediction of persistent trophoblastic activity after local prostaglandin F2 alpha injection for ectopic pregnancy.

A total of 60 patients underwent injection of prostaglandin (PG)F2 alpha into the affected tube and corpus luteum. Two serum samples, with a mean interval of 2.1 days, were taken pre-operatively and human chorionic gonadotrophin (HCG) and progesterone were determined by fluoroimmunoassay retrospectively. Cases requiring a second intervention (n = 8) were compared with uncomplicated cases (n = 52). The receiver-operator characteristic curve was used to determine optimal discriminatory levels of each diagnostic test. Among the complicated cases, 75% had progesterone values > 20 nmol/l and 100% had a daily HCG increase > 50 IU/l. The corresponding figures for the uncomplicated cases were 17% and 23% respectively. A 'high-risk' group representing 12% of the patient material was identified, and was biochemically profiled by serum progesterone values > 20 nmol/l, together with daily HCG changes > +50 IU/l/day. These patients had an 86% risk for a second intervention. Conversely, 88% of patients had only a 4% risk for such an intervention. We conclude that the combined use of two sequential serum HCG samples and one serum progesterone sample, the last of each taken not more than 24 h pre-operatively, can predict the risk for a complicated course following local injection of 15-methyl-PGF2 alpha for small tubal pregnancies.

Chorionic Gonadotropin↗
PubMed1999

Predicting Neisseria gonorrhoeae and Chlamydia trachomatis infection using risk scores, physical examination, microscopy, and leukocyte esterase urine dipsticks among asymptomatic women attending a family planning clinic in Kenya.

BACKGROUND: Sexually transmitted infections (STIs) continue to exert a tremendous health burden on women in developing countries. Poor socioeconomic status, inadequate knowledge, lack of diagnostic facilities, and shortages of effective treatment all contribute to the high incidence of STIs. The use of clinical algorithms for the detection and management of STIs has gained widespread acceptance in settings where there are limited resources. Evaluation of these algorithms have been few, especially in women who are not recognized as members of high-risk groups. OBJECTIVES: To develop a simple scoring system based on historical and demographic data, physical findings, microscopy, and leukocyte esterase (LE) urine dipsticks to predict cervical gonococcal and chlamydial infection among asymptomatic women. METHODS: One thousand and forty-eight women attending an urban family planning clinic in Nairobi were randomly selected to participate. After the identification of factors that were associated with infection, we assigned one point each for: age 25 or younger, single status, two or more sex partners in the past year, cervical discharge, cervical swab leukocytes, and a positive LE urine dipstick. Identification of any one of these six factors gave a sensitivity of 85% and a specificity of 30% for the detection of cervical infections. A positive LE urine dipstick had a sensitivity of 63 % and a specificity of 47% when used alone and did not contribute to the identification of infection if a physical examination was performed. The application of existing clinical algorithms to this population performed poorly. CONCLUSIONS: The use of risk scores, physical examination, microscopy, and the urine LE dipstick, used alone or in combination, as predictors of gonococcal or chlamydial cervical infection was of limited utility in low-risk, asymptomatic women. Accurate diagnostic testing is necessary to optimize treatment.

Adult↗
PubMed2003

Development of broad-range 16S rDNA PCR for use in the routine diagnostic clinical microbiology service.

The aim of the present study was to develop a broad-range PCR based on bacterial 16S rDNA for use in the routine diagnostic clinical microbiology service. The optimization and validation of the assay for use on clinical specimens from normally sterile sites is described, and preliminary results are reported on the use of the assay in the clinical diagnosis of bacterial infection in 382 paediatric specimens over a 2-year period. These results are compared to those obtained by standard culture techniques and show increased diagnosis of bacterial infection when both culture and PCR are used together; 16S rDNA PCR provided the sole evidence of pathogenic infection in 71 cases. Key stages in the assay development and potential pitfalls of the technique are highlighted and the improvement the assay offers in the diagnosis of infection in the paediatric setting is discussed.

Bacteria↗
PubMedDate not supplied

Quantitative evaluation of optical coherence tomography signal enhancement with gold nanoshells.

Nanoshell-enhanced optical coherence tomography (OCT) is a novel technique with the potential for molecular imaging and improved disease detection. However, optimization of this approach will require a quantitative understanding of the influence of nanoshell parameters on detected OCT signals. In this study, OCT was performed at 1310 nm in water and turbid tissue-simulating phantoms to which nanoshells were added. The effect of nanoshell concentration, core diameter, and shell thickness on signal enhancement was characterized. Experimental results indicated trends that were consistent with predicted optical properties-a monotonic increase in signal intensity and attenuation with increasing shell and core size. Threshold concentrations for a 2-dB OCT signal intensity gain were determined for several nanoshell geometries. For the most highly backscattering nanoshells tested-291-nm core diameter, 25-nm shell thickness-a concentration of 10(9) nanoshells/mL was needed to produce this signal increase. Based on these results, we discuss various practical considerations for optimizing nanoshell-enhanced OCT. Quantitative experimental data presented here will facilitate optimization of OCT-based diagnostics and may also be relevant to other reflectance-based approaches as well.

Contrast Media↗
PubMed2002

Quality assurance in stereotactic space. A system test for verifying the accuracy of aim in radiosurgery.

A detailed quality assurance (QA) program is essential for high precision single dose irradiations. The accuracy of stereotactic radiosurgery is limited by the errors of each step in the chain for optimal treatment beginning with the diagnostic imaging and target localization leading to the dose planning and ending up with the treatment of the patient. Two main goals were followed on the way to finding a concept for a suitable and sufficient quality assurance routine. First, the chain of items in terms of a complete patient simulation should be followed and second, the stereotactic MR image data should be verified against a reference in our case stereotactic radiographic projection images. Target point verifications were performed using the so-called, unknown target method based on MRI, CT, and stereotactic projection images. A marked radiochromic film, embedded between inserts of the phantom is fixed parallel to either the xy or the xz plane of the stereotactic coordinate system. After imaging and planning, the phantom is adjusted and irradiated. At the end, the film, dyed by the radiation field around the premarked cross, is evaluated. The measured distance between the unit center point (shadow) and the localization of the marked film leads to the deviation to be minimized. This is referred to as the displacement vector. The results, evaluating 170 system tests within 5 years. show that the mean displacement vector of the complete system is 0.48 mm +/-0.23 mm (mean+/- sd). Factors having a significant influence on the overall accuracy are associated with MRI parameters. Test results based on axial images (xy plane; 0.42 mm +/- 0.24 mm) are significantly superior to coronal images (xz plane; x = 0.60 mm +/- 0.02 mm). Further on, the 3D-mpr sequence (0.40 mm +/- 0.19 mm) is significantly superior to the T1 weighted SE sequences (0.66 mm +/- 0.24 mm). Given the high mechanical accuracy of the Leksell gamma knife, the most sensitive technical factor having an influence on the overall precision of radiosurgery is the MRI study. However, using the appropriate imaging sequences and parameters the dislocation error inferred by MRI can be kept very low and restricted to the rare patient inherent distortion factors. With these precautions in mind, MRI is recommended as the imaging method of choice in radiosurgery.

Biophysical Phenomena↗
PubMed2001

Etiology of children's diarrhea in Montevideo, Uruguay: associated pathogens and unusual isolates.

We studied microorganisms associated with infant diarrhea in a group of 256 children admitted to a public pediatric hospital in Montevideo, Uruguay. Diagnostic procedures were updated to optimize detection of potential pathogens, which were found in 63.8% of cases, and to be able to define their characteristics down to molecular or antigenic type. Coinfection with two or more agents was detected in more than one-third of positive studies. Escherichia coli enteric virotypes, especially enteropathogenic E. coli (EPEC), were shown to be prevalent. Rotavirus, Cryptosporidium, Campylobacter (mainly Campylobacter jejuni), and Shigella flexneri were also often identified. Enterotoxigenic E. coli, Salmonella, and Giardia lamblia were sporadically recognized. Unusual findings included two enteroinvasive E. coli strains, one Shigella dysenteriae 2 isolate, and a non-O:1 Vibrio cholerae culture. EPEC bacteria and S. flexneri (but not Salmonella) showed unusually frequent antimicrobial resistance, especially towards beta-lactam antibiotics, which is the subject of ongoing work.

Animals↗
PubMed2002

Optimal DNA isolation method for detection of bacteria in clinical specimens by broad-range PCR.

Broad-range amplification of bacterial DNA from clinical specimens has proved useful for the diagnosis of various bacterial infections, especially during antimicrobial treatment of the patient. Optimal sample processing protocols for diagnostic broad-range bacterial PCR should release DNA from an array of target organisms with equal efficiencies and wash out inhibitory factors from various sample types without introducing bacterial DNA contamination to the amplification reaction. In the present study, two physical cell wall disintegration methods, bead beating and sonication, for enhanced detection of organisms with difficult-to-lyse cell walls were studied. The analytical sensitivities of several commercially available DNA purification kits, which were used with and without additional cell disintegration steps, were compared by using dilution series of model bacteria. Selected purification methods were used to process routine clinical specimens in parallel with the standard phenol-ether DNA extraction, and the results obtained by bacterial PCR and sequencing with the two template preparations were compared. The method with the DNA isolation kit with the lowest detection limits from the bacterial suspensions (Masterpure) did not prove to be superior to the standard method when the two methods were applied to 69 clinical specimens. For another set of 68 clinical specimens, DNA purified with a glass fiber filter column (High Pure) with an additional sonication step yielded results well in accord with those obtained by the standard method. Furthermore, bacterial DNA was detected in four samples that remained PCR negative by the standard method, and three of these contained DNA from gram-positive pathogens. Three samples were positive by the standard method only, indicating the limitations of applying any single method to all samples.

Bacteria↗
PubMed1997

A citric acid solution is an optimal test drink in the 13C-urea breath test for the diagnosis of Helicobacter pylori infection.

BACKGROUND: The 13C-urea breath test (13C-UBT) is a simple, non-invasive and reliable test for the diagnosis of Helicobacter pylori infection. The duration of the test, the timing of breath sampling, and the accuracy of the method vary according to the test meal used. AIM: To identify the optimal test meal or drink for rapid and accurate performance of the 13C-UBT for the detection of H pylori infection. PATIENTS: Eighty patients with dyspeptic symptoms were included. Of these, 48 patients had a positive H pylori status and 32 a negative one according to the results of the rapid urease test, histological examination, and culture. METHODS: A 13C-UBT was performed after an overnight fast, on three consecutive days. On each study day a different test meal or drink was given (0.1 N citric acid solution, a standard semiliquid meal, or a semiliquid fatty meal) 10 minutes before giving 75 mg 13C-urea. Breath samples were collected at 0, 15, 30, 45, and 60 minutes, and analysed by isotype ratio mass spectrometry. Results were expressed as delta (delta) and considered as positive for H pylori if the highest delta (peak) was greater than 4.0. RESULTS: The delta peak obtained with the citric acid drink in H pylori positive subjects (24.1 (SEM 1.5)) was significantly higher than that obtained with any of the semiliquid meals (13.3 (SEM 1.1) and 17.1 (SEM 1.0) respectively, p < 0.001). Furthermore, this delta peak was obtained earlier with the citric acid drink (30 (SEM 2) minutes) than with the other two meals tests (53 (SEM 2) min and 45 (SEM 2) min, p < 0.001). The sensitivity of the 13C-UBT for the diagnosis of H pylori infection was 96-100% with all three test meals. This high sensitivity was, however, obtained from 15 minutes by giving citric acid as the test drink, from 45 minutes by giving a semiliquid fatty meal, and at 60 minutes by giving the semiliquid standard meal. The specificity was 100% for all test meals. Citric acid is inexpensive and palatable to patients. CONCLUSIONS: The 13C-UBT procedure with citric acid as the test drink is superior to the previously proposed semiliquid test meals in terms of 13CO2 recovery, time requirement, and cost. In routine clinical sampling, collection at times 0 and 30 minutes seems to be optimal and gives a high diagnostic accuracy.

Administration, Oral↗
PubMed2005

The differentiation between pancreatic neoplastic cysts and pancreatic pseudocyst.

The number of small and often asymptomatic cystic lesions detected in pancreas has increased during the last decade. Historically the vast majority of the pancreatic cystic lesions were considered pseudocysts, but in recent series the incidence of various neoplastic cysts, such as intraductal papillary mucinous neoplasm, serous cystadenomas and cystic endocrine tumours, has increased. The possible malignant potential in these cystic neoplasms warrants careful diagnostic workup to choose the optimal treatment for each patient. Patient's age, symptoms and a possible history of acute or chronic pancreatitis with known aetiology together with high quality imaging studies are important in the differential diagnosis between pseudocysts and neoplastic cysts. Endoscopic ultrasound, cyst fluid analysis and positron emission tomography may be used in selected patients, but the accuracy of these methods needs further investigation.

Algorithms↗