Validation of [13C]urea breath test for Helicobacter pylori using a simple gas chromatograph-mass selective detector

OBJECTIVE: Isotope ratio mass spectrometry (IRMS) is the accepted method for accurately measuring the 13CO2:12CO2 ratio in the non-invasive and non-radioactive [13C]urea breath test (13C-UBT) for Helicobactor pylori. The IRMS instrument, an expensive and highly specialized analyser, is rarely available. The objective of this project was to modify and validate the use of a simple bench-top gas chromatograph-mass selective detector (GC-MSD) for 13C-UBT. METHODS: Breath samples from 71 patients were taken at baseline and 30 min after ingestion of 100 mg [13C]urea. The breath samples were analysed using GC-MSD in the selected ion monitoring mode. The reference 13CO2:12CO2 ratio was from NBS19 obtained from the US National Institute of Standards and Technology. 13CO2:12CO2 ratios of the breath samples were determined. Excess delta per thousand (per mil, delta/thousand) of the 30 min sample over the baseline (deltadelta/thousand) of > or = 6deltadelta/thousand was considered H. pylori positive. Results from 13C-UBT and histology determined blind to each other were compared. RESULTS: The coefficient of variation of the reference 13CO2:12CO2 ratio was 0.06%. Using histology as the 'gold standard', the sensitivity (97.9%) and specificity (95.8%) of the GC-MSD 13C-UBT were comparable to those of other methods of H. pylori diagnosis. CONCLUSION: A gas chromatograph coupled to a mass selective detector that is available in many analytical and biomedical laboratories can be used for the 13C-UBT. This method will increase the availability and reduce the cost of this non-invasive, non-radioactive diagnostic test.     

Imaging approach to the diagnosis of pulmonary sequestration

PURPOSE: To describe the characteristic features of pulmonary sequestration (PS), to evaluate the usefulness of various imaging modalities, and to find a rational approach to accurate diagnosis. MATERIAL AND METHODS: Twenty-four patients with PS proved by operation and pathology were reviewed retrospectively. Plain chest films were done in all patients, bronchography in 3, sonography in 14, CT in 6 (including CT angiography in 1 case), MR in 8 (including MR angiography in 1 case) and aortography in 12 (including DSA in 1 case). RESULTS: Plain chest films demonstrated a solid mass in 14 patients and a cystic mass in 10. Bronchograms showed displacement of adjacent bronchi with no filling of contrast medium within the lesion in 2 cases, while another case had a blind intermediate portion of the right bronchus (hypoplasia of middle and lower lobes associated with extralobar sequestration). Sonography demonstrated a solid lung mass in 12 cases and a solid mass with cystic areas in 2, and detected vessel-like structures within the mass or in its surroundings in 12. Doppler analysis showed arterial spectral wave confirming a feeding artery. CT revealed a solid mass in all patients, a mass with low density area in 4, and emphysema surrounding the mass in 3. MR imaging depicted anomalous arteries in all patients and venous drainage in 4 cases. Aortography demonstrated anomalous systemic arterial supply to the PS in all patients. In this series, 21 cases (87.5%) were correctly diagnosed preoperatively by the imaging modalities. CONCLUSION: Plain chest films can provide a diagnostic clue to PS. Sonography, CT and MR are helpful for showing arterial blood supply and for making a definite diagnosis. We recommend a rational imaging approach for the diagnosis of PS.     

A natural kinase-deficient variant of fibroblast growth factor receptor 1

A fibroblast growth factor receptor 1 variant missing 37 amino acids from the carboxy-terminal tyrosine kinase catalytic domain was discovered in human lung fibroblasts and several other human cell lines. The receptor variant binds specifically to acidic fibroblast growth factor but has no tyrosine kinase activity. It was found that cellular transfectants expressing the fibroblast growth factor receptor 1 variant are mitogenically inactive and ligand binding to the receptor causes neither receptor autophosphorylation nor phospholipase C-gamma transphosphorylation. The fibroblast growth factor receptor 1 variant therefore represents an inactive receptor for acidic fibroblast growth factor. Since both kinase and kinase-deficient receptor forms are expressed in cells, it is conceivable that the kinase-deficient receptor plays an important role in regulating cellular responses elicited by acidic fibroblast growth factor stimulation.     

The hNT human neuronal cell line survives and migrates into rat retina

Pigs were fed a commercial conjugated linoleic acid (CLA) mixture, prepared by alkali isomerization of sunflower oil, at 2% of the basal diet, from 61.5 to 106 kg live weight, and were compared to pigs fed the same basal diet with 2% added sunflower oil. The total lipids from liver, heart, inner back fat, and omental fat of pigs fed the CLA diet were analyzed for the incorporation of CLA isomers into all the tissue lipid classes. A total of 10 lipid classes were isolated by three-directional thin-layer chromatography and analyzed by gas chromatography (GC) on long capillary columns and by silver-ion high-performance liquid chromatography (Ag+-HPLC); cholesterol was determined spectrophotometrically. Only trace amounts (<0.1%; by GC) of the 9,11-18:2 cis/trans and trans,trans isomers were observed in pigs fed the control diet. Ten and twelve CLA isomers in the diet and in pig tissue lipids were separated by GC and Ag+- HPLC, respectively. The relative concentration of all the CLA isomers in the different lipid classes ranged from 1 to 6% of the total fatty acids. The four major cis/trans isomers (18.9% 11 cis,13 trans-18:2; 26.3% 10 trans,12 cis-18:2; 20.4% 9 cis,11 trans-18:2; and 16.1% 8 trans, 10 cis-18:2) constituted 82% of the total CLA isomers in the dietary CLA mixture, and smaller amounts of the corresponding cis,cis (7.4%) and trans,trans (10.1%) isomers were present. The distribution of CLA isomers in inner back fat and in omental fat of the pigs was similar to that found in the diet. The liver triacylglycerols (TAG), free fatty acids (FFA), and cholesteryl esters showed a similar pattern to that found in the diet. The major liver phospholipids showed a marked increase of 9 cis,11 trans-18:2, ranging from 36 to 54%, compared to that present in the diet. However, liver diphosphatidylglycerol (DPG) showed a high incorporation of the 11 cis,13 trans-18:2 isomer (43%). All heart lipid classes, except TAG, showed a high content of 11 cis,13 trans-18:2, which was in marked contrast to results in the liver. The relative proportion of 11 cis,13 trans-18:2 ranged from 30% in the FFA to 77% in DPG. The second major isomer in all heart lipids was 9 cis,11 trans-18:2. In both liver and heart lipids the relative proportions of both 10 trans,12 cis-18:2 and 8 trans, 10 cis-18:2 were significantly lower compared to that found in the diet. The FFA in liver and heart showed the highest content of trans,trans isomers (31 to 36%) among all the lipid classes. The preferential accumulation of the 11 cis,13 trans-18:2 into cardiac lipids, and in particular the major phospholipid in the inner mitochondrial membrane, DPG, in both heart and liver, appears unique and may be of concern. The levels of 11 cis,13 trans-18:2 naturally found in foods have not been established.     

Thyrotoxicosis and renal tubular acidosis presenting as hypokalaemic paralysis

We report a case of oesophageal disease as the first manifestation in a patient with CREST syndrome. A 46-year-old man with achalasia-like syndrome developed CREST syndrome 4 years later. A pneumatic dilatation of the cardia was performed. After pneumatic dilatation the dysphagia and regurgitation disappeared but the patient developed reflux oesophagitis. Four years after diagnosis of oesophageal disease he presented with a clinical picture of CREST syndrome. An acute ileus and constipation developed later. After receiving medical therapy with omeprazole and cisapride the patient is free of oesophageal symptoms and bowel movements are normal. Oesophageal disease is common in patients with limited and diffuse scleroderma, but to our knowledge achalasia-like syndrome has not been previously described as the first manifestation of the systemic disease.     

Study of bending-induced strain effects on MuGFET performance

The impact of stress induced by biaxial mechanical bending on multiple-gate FET (MuGFET) performance is studied. For relatively low levels of bending-induced surface strain (/spl sim/ 0.1%), significant enhancements in the driving current can be achieved and maintained with gate-length scaling. This makes package strain a potentially attractive approach to enhancing MuGFET-based CMOS performance at low cost. For bending-induced strain, the enhancements in electron mobility and [110] hole mobility are well predicted by the piezoresistance model using the coefficients for bulk-Si, but the impact of stress on (100) hole mobility is more complex.     

Isolation and characterization of phenol-degrading denitrifying bacteria

Phenol is a man-made as well as a naturally occurring aromatic compound and an important intermediate in the biodegradation of natural and industrial aromatic compounds. Whereas many microorganisms that are capable of aerobic phenol degradation have been isolated, only a few phenol-degrading anaerobic organisms have been described to date. In this study, three novel nitrate-reducing microorganisms that are capable of using phenol as a sole source of carbon were isolated and characterized. Phenol-degrading denitrifying pure cultures were obtained by enrichment culture from anaerobic sediments obtained from three different geographic locations, the East River in New York, N.Y., a Florida orange grove, and a rain forest in Costa Rica. The three strains were shown to be different from each other based on physiologic and metabolic properties. Even though analysis of membrane fatty acids did not result in identification of the organisms, the fatty acid profiles were found to be similar to those of Azoarcus species. Sequence analysis of 16S ribosomal DNA also indicated that the phenol-degrading isolates were closely related to members of the genus Azoarcus. The results of this study add three new members to the genus Azoarcus, which previously comprised only nitrogen-fixing species associated with plant roots and denitrifying toluene degraders.     

Emergency postcoital contraception

Pancreatitis may be acute or chronic, mild or severe. Acute necrotizing pancreatitis remains the most serious form of acute pancreatitis and accounts for the majority of complications. Although there is an established nomenclature for pancreatitis and pancreatic fluid collections, such as pancreatic pseudocysts, it is not widely understood or recognized by gastroenterologists. Because the management options for the treatment of pancreatic fluid collections continues to evolve with an increased use of endoscopic therapy, gastroenterologists will be increasingly called on to treat patients with pancreatitis and its complications. This article addresses and summarizes pancreatic fluid collections and their management, with an emphasis on endoscopic drainage.