Metabolite collision cross section prediction without energy-minimized structures.

Matching experimental ion mobility-mass spectrometry data to computationally-generated collision cross section (CCS) values enables more confident metabolite identifications. Here, we show for the first time that accurately predicting CCS values with simple models for the largest library of metabolite cross sections is indeed possible, achieving a root mean square error of 7.0 Å2 (median error of ∼2%) using linear methods accesible to most researchers. A comparison on the performance of 2D vs. 3D molecular descriptors for the purposes of CCS prediction is also presented for the first time, enabling CCS prediction without a priori knowledge of the metabolite's energy-minimized structure.

Calcific tendonitis of the quadriceps tendon.

A 61-year-old woman presented with chronic anterior pain and stiffness in the distal left thigh. Examination revealed swelling and tenderness immediately proximal to the patella. Radiographs showed opacities in the distal anterior thigh whilst MRI identified enlargement of the distal quadriceps tendon with splayed fibres separated by solid conglomerates. Dystrophic calcification of the quadriceps tendon was diagnosed. Blood tests revealed no systemic abnormalities in calcium handling. Arthroscopy of the left knee identified calcific deposits in the supra-patella pouch with surrounding synovitis. An open debridement of the tendon was performed; biopsy of the excised tendon showed chronic tenosynovitis with dystrophic calcification without evidence of malignancy. Post-operatively her knee was braced in extension enabling progressive flexion over 4 weeks. Anterior knee pain diminished post-operatively and 10 months following surgery the patient was pain free, able to walk normally and scored 99/100 on the Fulkerson modification of the Lysholm score.

Collision cross section predictions using 2-dimensional molecular descriptors.

Traditional methods for deriving computationally-generated collision cross sections for comparisons with ion mobility-mass spectrometry data require 3-dimensional energy-minimized structures and are often time consuming, preventing high throughput implementation. Here, we introduce a method to predict ion mobility collision cross sections of lipids and peptide analogs important in prebiotic chemistry and other fields. Using less than 100 2-D molecular descriptors this approach resulted in prediction errors of less than 2%.

The reliability of measuring the density of the L1 vertebral body on CT imaging as a predictor of bone mineral density.

AIM: To determine whether the density of the L1 vertebra measured on computed tomography (CT) images correlates with the bone mineral density (BMD) as measured by quantitative computed tomography (QCT), and to determine the reliability of L1 density measurements by different observers to see if this measure could help identify patients who would benefit from formal BMD assessment. MATERIALS AND METHODS: Non-contrast CT along with a phantom for determination of BMD was performed on 30 healthy patients. The L1 density was measured by 3 observers at two time-points separated by at least 2 weeks. RESULTS: L1 density was well correlated to the QCT BMD (correlation coefficient 0.83; 95% confidence interval [CI]: 0.67-0.92). There was excellent intra- and interobserver agreement in L1 density measurements. There were excellent intra-class correlation coefficients for each observer's measurements at two separate time points with a coefficient for observer 1 of 0.94 (95% CI: 0.88-0.97) and for observer 2 and 3 of 0.99 (95% CI: 0.98-1). The interobserver measurements had an intra-class correlation coefficient of 0.98 (95% CI: 0.96-0.99). CONCLUSION: L1 vertebral density can be reliably measured on CT images and might be used as an indicator of BMD for opportunistic screening of patients with osteoporosis. Low bone density detected incidentally on CT imaging could be used to identify patients who should be further investigated and treated for osteoporosis.

Radiological imaging of congenital hand anomalies--a 6-year single-centre experience and what the hand surgeons want to know.

OBJECTIVE: Congenital hand anomalies present a rare but important physical and emotional challenge for children and parents. Radiological imaging is important for accurate diagnosis, to aid decision making and to monitor changes in the growing hand. The goal of any treatment is to help the child achieve his/her maximum potential, to provide a useful hand with attention to cosmesis. We investigated the range of congenital hand anomalies imaged in a tertiary referral centre. We examined the timing of imaging and the key clinical questions. METHODS: The radiology imaging system was searched retrospectively for radiographs of congenital hand anomalies over a 6-year period. The images were reviewed and patient demographics, diagnosis and other imaging recorded. RESULTS: Over 6 years, 85 patients had imaging. Twenty-three patients had bilateral problems and 11 had recognised syndromes. The most common abnormalities imaged were duplicated thumbs (28 %), followed by syndactyly (18 %). Children were first imaged as early as 1 day old, with the median age of initial imaging 12 months. CONCLUSIONS: Thumb duplication and syndactyly are the most common conditions for which radiographs are requested at our hospital, although overall syndactyly is considered the most common congenital hand anomaly. For a variety of reasons, children are often imaged very early, before review by the Specialist in Children's Hand Surgery (despite surgery being unlikely before 1 year of age.) We discuss the classification systems and specific issues that hand surgeons want to know from the radiologists.

Spinal chondrosarcoma arising from a solitary lumbar osteochondroma.

Chondrosarcoma is a primary malignant neoplasm of cartilage-forming cells that rarely involves the axial skeleton, typically affecting skeletally mature patients. It may arise as a primary bone tumour or as a secondary lesion from a pre-existing benign cartilaginous neoplasm such as an osteochondroma or enchondroma. We report the case of a 68-year-old female who presented with a mildly painful paraspinal mass lesion as a result of malignant degeneration of a previously unknown solitary lumbar osteochondroma into a large chondrosarcoma. The characteristic imaging findings on cross-sectional imaging techniques are reviewed and illustrated, along with an outline of relevant clinical and therapeutic aspects.

A new CT grading system for hip osteoarthritis.

OBJECTIVES: We have developed a new grading system for hip osteoarthritis using clinical computed tomography (CT). This technique was compared with Kellgren and Lawrence (K&L) grading and minimum joint space width (JSW) measurement in digitally reconstructed radiographs (DRRs) from the same CT data. In this paper we evaluate and compare the accuracy and reliability of these measures in the assessment of radiological disease. DESIGN: CT imaging of hips from 30 female volunteers aged 66 ± 17 years were used in two reproducibility studies, one testing the reliability of the new system, the other testing K&L grading and minimum JSW measurement in DRRs. RESULTS: Intra- and inter-observer reliability was substantial for CT grading according to weighted kappa (0.74 and 0.75 respectively), while intra- and inter-observer reliability was at worst moderate (0.57) and substantial (0.63) respectively for DRR K&L grading. Bland-Altman analysis showed a systematic difference in minimum JSW measurement of 0.82 mm between reviewers, with a least detectable difference of 1.06 mm. The area under the curve from ROC analysis was 0.91 for our CT composite score. CONCLUSIONS: CT grading of hip osteoarthritis (categorised as none, developing and established) has substantial reliability. Sensitivity was increased when CT features of osteoarthritis were assigned a composite score (0 = none to 7 = severest) that also performed well as a diagnostic test, but at the cost of reliability. Having established feasibility and reliability for this new CT system, sensitivity testing and validation against clinical measures of hip osteoarthritis will now be performed.

Severity mapping of the proximal femur: a new method for assessing hip osteoarthritis with computed tomography.

OBJECTIVE: Plain radiography has been the mainstay of imaging assessment in osteoarthritis for over 50 years, but it does have limitations. Here we present the methodology and results of a new technique for identifying, grading, and mapping the severity and spatial distribution of osteoarthritic disease features at the hip in 3D with clinical computed tomography (CT). DESIGN: CT imaging of 456 hips from 230 adult female volunteers (mean age 66 ± 17 years) was reviewed using 3D multiplanar reformatting to identify bone-related radiological features of osteoarthritis, namely osteophytes, subchondral cysts and joint space narrowing. Scoresheets dividing up the femoral head, head-neck region and the joint space were used to register the location and severity of each feature (scored from 0 to 3). Novel 3D cumulative feature severity maps were then created to display where the most severe disease features from each individual were anatomically located across the cohort. RESULTS: Feature severity maps showed a propensity for osteophytes at the inferoposterior and superolateral femoral head-neck junction. Subchondral cysts were a less common and less localised phenomenon. Joint space narrowing <1.5 mm was recorded in at least one sector of 83% of hips, but most frequently in the posterolateral joint space. CONCLUSIONS: This is the first description of hip osteoarthritis using unenhanced clinical CT in which we describe the co-localisation of posterior osteophytes and joint space narrowing for the first time. We believe this technique can perform several important roles in future osteoarthritis research, including phenotyping and sensitive disease assessment in 3D.

Meniscal tear evaluation. Comparison of a conventional spin-echo proton density sequence with a fast spin-echo sequence utilizing a 512 × 358 matrix size.

AIM: To determine the sensitivities, specificities, and receiver-operating characteristics (ROCs) for sagittal conventional spin-echo proton density (SE-PD) and fast spin-echo proton density (FSE-PD) sequences in the diagnosis of meniscal tears when compared to arthroscopic findings utilizing increased FSE matrix acquisition size. METHOD AND MATERIALS: Magnetic resonance imaging (MRI) studies of 97 knees (194 menisci) were independently and prospectively interpreted by two experienced musculoskeletal radiologists over four separate readings at least 3 weeks apart. Readings 1 and 2 included images in all three planes in accordance with the standard protocol with either a SE or FSE sagittal PD, at readings 3 and 4 just the SE or FSE sagittal PD sequences were reported. The FSE sequence was acquired with an increased matrix size, compared to the SE sequence, to provide increased resolution. Menisci were graded for the presence of a tear and statistical analysis to calculate sensitivity and specificity was performed comparing to arthroscopy as the reference standard. ROC analysis for the diagnosis of meniscal tears on the SE and FSE sagittal sequences was also evaluated. Reader concordance for the SE and FSE sequences was calculated. RESULTS: Sixty-seven tears were noted at arthroscopy; 60 were detected on SE and 56 on FSE. The sensitivity and specificity for SE was 90 and 90%, and for FSE was 84 and 94%, respectively, with no significant difference. ROC analysis showed no significant difference between the two sequences and kappa values demonstrated a higher level of reader agreement for the FSE than for the SE reading. CONCLUSION: Use of a FSE sagittal PD sequence with an increased matrix size provides comparable performance to conventional SE sagittal PD when evaluating meniscal disease with a modern system. The present study indicates an increased level of concordance between readers for the FSE sagittal sequence compared to the conventional SE.

Fluoroscopic insertion of post-pyloric feeding tubes: success rates and complications.

AIM: To examine the success and complication rates of radiological placement of post-pyloric feeding tubes, including those inserted with the assistance of a guide-wire. MATERIALS AND METHODS: Two hundred referrals (156 patients), between the dates of 5 April 2002 and 10 September 2004, were identified retrospectively from computerized records. Subsequently, the radiology reports and patients' notes were reviewed to evaluate the indications for post-pyloric feeding, success of placement, use of a guide-wire, and any complications. RESULTS: A post-pyloric tube was placed in the distal duodenum/jejunum in 183 (91.5%) patients and in the proximal duodenum or distal stomach in six (3%). A tube could not be inserted in 11 (5.5%) patients, and 51 (25.5%) of the insertions required the use of a guide-wire. Immediate complications were recorded in seven patients (3.5%): vomiting (n=5); hypotension and apnoea requiring naloxone (n=1) and hypoxia requiring endotracheal intubation (n=1). CONCLUSION: Radiological placement of post-pyloric feeding tubes has a success rate comparable with endoscopically placed tubes, and it rarely involves significant technique-related complications.

Outcome of hypospadias fistula repair.

Objectives To examine the long-term results of hypospadias fistula repair, the factors involved in recurrence and the outcome in cases where this has occurred. Patients and methods The study comprised 113 children undergoing urethrocutaneous fistula repair between 1984 and 1996. Most of the fistulae were closed in two to three layers, with or without a transpositional skin flap. Tunica vaginalis or a scrotal dartos flap was used in patients with inadequate vascularized tissue adjacent to the fistula. Success rates were calculated for each attempt at fistula repair until the patient was cured. Results The median (range) age at primary fistula repair was 40 (18-169) months and the median follow-up after the most recent repair 7.5 (2.3-17) years. The overall success rate of primary fistula repair was 71%. Fistulae which were >2 mm (11 of 21, 52%) were more likely to recur than were those < or = 2 mm (22 of 92, 24%). Recurrence did not relate to the initial form of hypospadias repair, to the means of skin closure nor, with the exception of multiple lesions, to the location of the fistula. The success rates of subsequent repairs were 70% at the second and 50% at the third, fourth and fifth repairs. One child was cured at the sixth attempt. The use of tunica vaginalis or scrotal dartos as a 'waterproofing' layer was limited to the third or subsequent repairs and was successful in five of six cases. Conclusion A simple layered closure with or with no transpositional skin flap is effective in 71% of repairs. For recurrent fistulae, tissues from an unscarred area (tunica vaginalis or scrotal dartos layer) should be used to cover the fistula.

Automated one-step supercritical fluid extraction and clean-up system for the analysis of pesticide residues in fatty matrices.

An automated supercritical fluid extraction and in-line clean-up system has been developed for organochlorine and organophosphate pesticide residues contained in fats. This procedure utilizes supercritical carbon dioxide modified with 3% acetonitrile at 27.58 MPa and 60 degrees C to extract and separate the pesticide residues from the fat on a C1 bonded phase preparative column at 95 degrees C. The automated C1 system recovers 86 of 117 nonpolar to moderately polar organochlorine and organophosphate pesticides from fats. Ten of the 31 pesticides not recovered through the system are not recovered through the conventional clean-up sorbent, Florisil. Pesticide residues can be separated from 0.68 g of butter fat and 0.67 g corn oil, resulting in 2.9 mg of butterfat and 2.1 mg corn oil residue co-eluting into the pesticide fraction. Also, this integrated method can extract and clean-up a 5 g sample of fatty foods containing < 18% fat and 70% moisture. The automated C1 system is reproducible and the amount of co-extracted sample residue in the pesticide fraction yields results comparable to the current methodology, which uses organic solvent extraction and gel permeation chromatography, along with a final Florisil column clean-up step. This automated C1 system simplifies the extraction and clean-up step while reducing solvent usage and hazardous waste.

Automated method for cleanup and determination of benomyl and thiabendazole in table-ready foods.

An automated solid-phase extraction (SPE) cleanup with on-line liquid chromatographic (LC) analysis was developed to determine residues of benomyl (as carbendazim) and thiabendazole in table-ready food items from the U.S. Food and Drug Administration Total Diet Study (TDS). A strong-cation-exchange cleanup of an acetone extract replaces the methylene chloride solvent partitioning steps in the procedure described in the Pesticide Analytical Manual (PAM). LC analysis is accomplished with a C8 analytical column and tandem fluorescence and UV detection. Recoveries of both analytes from 32 representative TDS foods fortified at 0.05 and 0.5 microgram/g were determined. Method precision was evaluated with triplicate recovery assays on 11 foods fortified at both levels. Accuracy was tested further by assaying 47 foods for incurred residues in parallel with the validated PAM procedure for comparison, and good agreement was found. The automated SPE method reduces solvent consumption, analysis time, and labor.

Extraction and cleanup of organochlorine and organophosphorus pesticide residues in fats by supercritical fluid techniques.

A supercritical fluid extraction and cleanup procedure was developed for separating organochlorine and organophosphorus pesticides from fats. Supercritical carbon dioxide modified with 3% (v/v) acetonitrile was used to extract the pesticides at 60 degrees C and separate the pesticides from the fats at 4000 psi and 95 degrees C on an in-line, C1 silica-based column. The extraction and cleanup procedure gave good recoveries for 43 of 62 nonpolar to moderately polar organochlorine and organophosphorus pesticides from fats, whereas 49 were recovered through conventional Florisil column cleanup before quantitation. This procedure can extract and clean up pesticide residues from 0.65 g animal-based fat and 1.0 g oils. Coeluted residues in the pesticide fraction ranged from 2.5 mg for butterfat to 0.8 mg for corn oil. Results for samples analyzed with this integrated extraction cleanup procedure were reproducible and comparable with results obtained with the current Total Diet Study methodology.

Multivessel supercritical fluid extraction of food items in Total Diet Study.

An off-line, large capacity, multivessel supercritical fluid extractor (SFE) was designed and constructed for extraction of large samples. The extractor can simultaneously process 1-6 samples (15-25 g) by using supercritical carbon dioxide (SC-CO2), which is relatively nontoxic and nonflammable, as the solvent extraction medium. Lipid recoveries for the SFE system were comparable to those obtained by blending or Soxhlet extraction procedures. Extractions at 10,000 psi, 80 degrees C, expanded gaseous CO2 flow rates of 4-5 L/min (35 degrees C), and 1-3 h extraction times gave reproducible lipid recoveries for pork sausage (relative standard deviation [RSD], 1.32%), corn chips (RSD, 0.46%), cheddar cheese (RSD, 1.14%), and peanut butter (RSD, 0.44%). In addition, this SFE system gave reproducible recoveries (> 93%) for butter fortified with cis-chlordane and malathion at the 100 ppm and 0.1 ppm levels. Six portions each of cheddar cheese, saltine crackers, sandwich cookies, and ground hamburger also were simultaneously extracted with SC-CO2 and analyzed for incurred pesticide residues. Results obtained with this SFE system were reproducible and comparable with results from organic-solvent extraction procedures currently used in the Total Diet Study; therefore, use and disposal of large quantities of organic solvents can be eliminated.

Stroke volume measurement during supine and upright cycle exercise by impedance cardiography.

This study evaluated impedance cardiography (ZCG) estimates of stroke volume (SV) during exercise. Seven subjects were studied at rest and during progressive cycle exercise in supine and upright positions. SV was determined by ZCG (SVZCG) during exercise and for the first 5 cardiac cycles following exercise. SVZCG was compared with separate measurements of SV by CO2 rebreathing (SVCO2). Static blood resistivity (p) was measured at each level of exercise. No significant differences were found between supine exercise and immediate post-exercise values for the peak of the first derivative of the impedance change (dZ/dtmax), left ventricular ejection time (LVET), or SVZCG. Small differences in dZ/dtmax and SVZCG, but not LVET, were found in exercise to post-exercise cycling in the upright position. Intra-individual SVZCG and SVCO2 were moderately correlated (upright mean r = 0.64, supine r = 0.42) from rest to 70% of peak VO2. Similar correlations were found between Pulse-O2 (VO2/heart rate, used as an index to SV) and both SVZCG (upright r = 0.73, supine r = 0.57) and SVCO2 (upright r = 0.8, supine r = 0.65). The ZCG parameters dZ/dtmax and LVET correlated better with Pulse-O2 (dZ/dtmax: upright r = 0.92, supine r = 0.73; LVET: upright r = -0.9, supine r = -0.9). SVZCG calculated with the Kubicek equation performed as well as SVCO2. ZCG might be a superior method if the inversely correlated parameters, dZ/dtmax and LVET, were not expressed as a product to calculate SV.

Analysis of organochlorine pesticide residues using simultaneous injection of two capillary columns with electron capture and electrolytic conductivity detectors.

A system has been developed that will allow low level screening of 31 organochlorine pesticide residues using simultaneous injection on 2 dissimilar capillary columns. An electron capture detector was attached to a DB-1701 column, and an electrolytic conductivity detector in the halogen mode was attached to a DB-5 column. Chlorinated pesticide amounts ranging from 0.05 ng for gamma-BHC to 1.5 ng for decamethrin can easily be quantitated and confirmed. The system can be used in either the column programmed mode or the isothermal column mode. Good reproducibility was obtained for injections in both modes. This system can easily be retrofitted to any gas chromatograph using on column or split/splitless injectors.

Enhanced supercritical fluid carbon dioxide extraction of pesticides from foods using pelletized diatomaceous earth.

Supercritical fluid carbon dioxide (SC-CO2), when used with an extraction enhancer, comprises a supercritical fluid extraction (SFE) system for extraction of pesticides and matrix components from fatty and nonfatty foods. After being mixed with the enhancer, samples ranging from 95% water to pure lipophilic oils can be extracted efficiently with SC-CO2. This extraction technique yields analyte recoveries in excess of 85% for over 30 types of pesticides at incurred levels ranging from 0.005 to 2 ppm in such diverse matrixes as carrots, lettuce, peanut butter, hamburger, and fortified butter fat and fortified potatoes. SC-CO2 provides a solvent medium that is nontoxic, nonflammable, and inexpensive while also eliminating the use and disposal of potentially carcinogenic organic solvents.