Two types of intraoral distribution of fluorotic enamel

Assessment of body composition remains a goal for the routine assessment of nutritional status of patients on long-term dialysis. Methods generally available for estimation of body fat in healthy individuals are limited by practicality and availability for use in this patient population. Anthropometry, which is cost effective and easy to perform, is limited by the lack of appropriate reference standards for patients on dialysis and artifact caused by hydration status. Bioelectrical impedance affords new opportunities for non-invasive assessment of fluid volume, its distribution, and body cell mass; estimation of fat-free mass and body fat can be affected by hydration status. Dual x-ray absorptiometry permits estimation of bone status and fat mass because changes in hydration status are reflected in estimates of fat-free mass. Evaluation of validity of techniques for fluid status and body composition assessment requires the use of appropriate reference methods and proper statistical procedures to examine error, not only between groups, but by individual. Use of body composition assessment methods together with biochemical measurements will enhance the nutritional assessment of end-stage renal disease patients on long-term hemodialysis.     

Osteocalcin and osteonectin immunoreactivity in the diagnosis of osteosarcoma

Osteosarcomas (OSAs) can be difficult to distinguish histologically from tumors with significantly different biologic potentials and treatment protocols. The correct diagnosis of OSA relies on identification of malignant osteoblasts that are capable of producing neoplastic bone. To determine the use of immunohistochemistry for the diagnosis of OSA, 106 tumors from the Massachusetts General Hospital and the University of Vermont were immunostained with monoclonal antiosteocalcin (OC) and antiosteonectin (ON) antibodies. They included 42 OSAs, 25 non-bone-forming sarcomas, 24 other malignant tumors including lymphomas, carcinomas, and melanomas, and 15 benign bone tumors. Cytoplasmic staining with OC showed 70% sensitivity and 100% specificity, while staining with ON showed 90% sensitivity and 54% specificity for bone-forming tumors, consistently staining cell types other than osteoblasts. Of the OSAs, 83% demonstrated matrix staining with one or both antibodies, whereas dense collagen was negative for both antibodies in all tumors. We conclude that tumor cell cytoplasmic staining with monoclonal OC may be helpful in distinguishing OSAs from other malignancies, and staining of extracellular matrix for OC and ON antibodies concurrently may help distinguish bone matrix from dense collagen.     

Substantial narrowing of the Niemann-Pick C candidate interval by yeast artificial chromosome complementation

Niemann-Pick disease type C (NP-C) is an autosomal recessive lipidosis linked to chromosome 18q11-12, characterized by lysosomal accumulation of unesterified cholesterol and delayed induction of cholesterol-mediated homeostatic responses. This cellular phenotype is identifiable cytologically by filipin staining and biochemically by measurement of low-density lipoprotein-derived cholesterol esterification. The mutant Chinese hamster ovary cell line (CT60), which displays the NP-C cellular phenotype, was used as the recipient for a complementation assay after somatic cell fusions with normal and NP-C murine cells suggested that this Chinese hamster ovary cell line carries an alteration(s) in the hamster homolog(s) of NP-C. To narrow rapidly the candidate interval for NP-C, three overlapping yeast artificial chromosomes (YACs) spanning the 1 centimorgan human NP-C interval were introduced stably into CT60 cells and analyzed for correction of the cellular phenotype. Only YAC 911D5 complemented the NP-C phenotype, as evidenced by cytological and biochemical analyses, whereas no complementation was obtained from the other two YACs within the interval or from a YAC derived from chromosome 7. Fluorescent in situ hybridization indicated that YAC 911D5 was integrated at a single site per CT60 genome. These data substantially narrow the NP-C critical interval and should greatly simplify the identification of the gene responsible in mouse and man. This is the first demonstration of YAC complementation as a valuable adjunct strategy for positional cloning of a human gene.     

Measurement of adenylylcyclase activity in the AV nodal region of the canine heart: evidence for inhibition by adenosine and acetylcholine

We simultaneously recorded gastric emptying of radio-opaque markers (ROMs) and monitored serial changes in plasma acetaminophen (AAP) levels to demonstrate the relationship between the ROM and the AAP methods, and we investigated the effect of a single intravenous dose of erythromycin (EM) on gastric emptying in healthy human subjects. After an overnight fast, subjects were randomized to receive either placebo or EM lactobionate (Abbott, North Chicago, IL, USA) 250 mg intravenously in a single dose, given immediately before a standard meal. Subjects ingested 1.5 g of AAP and ROMs with the test meal. A supine plain abdominal radiograph was taken 1, 2, 3, and 6 h after ingestion of the test meal. Peripheral blood samples were obtained 0, 0.5, 1, 1.5, 2, 3, and 6 h after ingestion of the test meal. EM significantly accelerated gastric emptying of ROMs. By 6 h, no markers remained in the stomach in any of the subjects in the placebo or EM groups. By 120 min, half of the ROMs had passed into the duodenum in 12.5% of subjects after placebo, whereas EM injection resulted in gastric emptying of half of the ROMs in all subjects. There was no difference in plasma AAP concentration between the placebo and EM groups. There were significant correlations between maximum plasma AAP concentration and gastric emptying of ROMs 120 min after ingestion (r = 0.546; P = 0.019), and between time of maximum plasma AAP concentration and gastric emptying of ROMs 120 min after ingestion (r = -0.568; P = 0.014). The time taken to reach the peak concentrations ranged from 30 to 90 min after ingestion, whereas most ROMs were emptied 120 min after ingestion. We conclude that the gastric emptying assessed by ROMs and by serial changes in plasma AAP level are good, non-invasive, clinically applicable tests, with a significant correlation between the two tests. A single intravenous dose of EM had a prokinetic effect on gastric emptying, assessed by ROMs, in healthy human subjects.     

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.