Biomedical subjects
Publications and source records attributed to H Yan.
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The relationship between convolution/correlation operation and the data acquisition process of the scanning microscope and spectrometer families is analyzed. It is shown that a coordinate or event sensitive detector, and the intrinsic or extrinsic property of the specimen response, are two important factors in distinguishing the data acquisition mode of such systems. Four types of convolution- and correlation-based modes are extracted to illuminate the physical characteristics of scanning imaging and analysis systems by focusing on the probe, specimen, detector, and their relationships. Criteria for identifying these modes are explored. In addition, the physical meanings of general existing coefficients between the independent variables of convolution and correlation are investigated.
Specialized antigen-presenting cells (APC), known as dendritic cells (DC), play a pivotal role in initiating primary immune responses. Several vector systems, including adenoviral vectors, retroviral vectors, hemagglutinating virus of Japan-related vectors, and the electroporation, have been shown to transduce genes into mouse and human but not rat DC. However, there is no direct evidence to support the view that the currently used vector systems are able to transduce genes into mature DC. Inasmuch as most, if not all, gene transfer studies investigating DC or DC-related cell populations are performed employing heterogeneous-groups of cells, it is therefore important to determine the extent to which gene transduction occurs in bona fide DC. In this study, we provide evidence that none of these vector systems are able to transfer genes into mature rat DC, which are derived from bone marrow cells (BMC), driven by Flt3/Flk2 ligand and IL-6, and purified with CD161a. Nevertheless, the most efficient gene transduction was observed with developing DC progenitor cells during long-term culture of rat BMC. Successful gene transfer was achieved after 2-week culture with an HIV-based lentiviral vector system.
Evidence is provided that dendritic cells (DC) generated by either long-term bone marrow cell (BMC) culture with Flt3L and interleukin-6 (IL-6), or after short-term BMC culture with granulocyte macrophage-colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4), contain heterogeneous cell populations of admixed DC and Mphi, regardless of the cytokine source. By employing GM-CSF-independent culture systems with the aid of Flt3/Flk-2 ligand and IL-6 and phenotypic characterization of BMC-derived DC and skin Langerhans cells (LC), revealed similar phenotypes. Furthermore, CD103 (OX62), which is widely used for rat DC separation, was found to be insufficient to enrich DC, due to downregulation of the marker. In this regard, the most efficient selection of rat DC, was obtained by CD161a (NKR-P1A), a member of the C-type lectin family. Despite the phenotypic similarity with BMC-derived DC, the nucleus of LC showed a distinct morphology. A large population of DC generated by Flt3L/IL-6 from GM-CSF receptor-deficient mice by do not express NK1.1 (NKR-P1B and NKR-P1C). The profiles for BMC-derived DC were the same as for skin Langerhans cells.
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Nitrotoluenes are important intermediates in the chemical industry. 2,6-Dinitrotoluene (26DNT), 2,4-dinitrotoluene (24DNT) and 2-nitrotoluene (2NT) are carcinogenic in animals and possibly carcinogenic in humans. Thus, it is important to develop methods to biomonitor workers exposed to such chemicals. The authors have monitored the air and urine metabolite levels for a group of workers in China exposed to 24DNT, 26DNT, 2NT and 4-nitrotoluene (4NT). The metabolites 2,4-dinitrobenzylalcohol (24DNBAlc), 2-amino-4-nitrobenzoic acid (2A4NBA), 4-amino-2-nitrobenzoic acid (4A2NBA) and 2,4-dinitrobenzoic acid (24DNBA) resulting from exposure to 24DNT were found in 89, 88, 91 and 78% of the exposed workers, respectively. The metabolites 2,6-dinitrobenzylalcohol (26DNBAlc) and 2,6-dinitrobenzoic acid resulting from 26DNT exposure were found in 99 and 86% of the exposed workers, respectively. Quantitatively, 2A4NBA, 4A2NBA and 26DNBAlc were the major metabolites. The nitrobenzoic acids were the major metabolites resulting from exposure to 2NT and 4NT and were present in 96 and 73% of the exposed workers, respectively. Air concentrations of DNT and 2NT did not correlate with the levels of metabolites in the urine. In conclusion, the dinitrobenzyl alcohols and aminonitrobenzoic acids determined in the urine provided a good marker for recently absorbed dose and were intrinsically related to the bioactivation and detoxification pathways of DNT. Air measurements were not a good measure to predict internal exposure.
BACKGROUND: Currently available bedside methods for determining feeding tube placement often provide inconclusive results. Therefore, additional data are needed to assist nurses in making decisions regarding tube location. OBJECTIVES: To describe the usual concentration of bilirubin in aspirates from newly inserted feeding tubes and to determine the extent to which these measures can contribute to pH alone in correctly predicting feeding tube location. METHODS: Gastrointestinal samples for concurrent pH and bilirubin testing were obtained from adult, acutely ill patients with newly inserted small-bore feeding tubes (nasogastric, n = 209; nasointestinal, n = 228) within 5 minutes of radiographs taken to determine tube location. Respiratory samples were tested (tracheobronchial, n = 126; pleural, n = 24). pH was measured with a pH meter, and bilirubin content was assayed spectrophotometrically. Results from the pH and bilirubin tests were compared with tube location as determined by radiography. RESULTS: Mean pH levels in the lung (7.73) and intestine (7.35) were significantly higher than the mean pH level in the stomach (3.90; p < .001 for each comparison). Mean bilirubin levels in the lung (.08 mg/dl) and stomach (1.28 mg/dl) were significantly lower than the mean bilirubin level in the intestine (12.73 mg/dl; p < .001 for each). By visually inspecting distribution overlap and mean differences by tube site, results were dichotomized so that a combination of pH and bilirubin values could be used to develop a predictive algorithm. A pH of >5 and a bilirubin value of <5 mg/dl correctly identified all respiratory cases, whereas a pH >5 coupled with a bilirubin level of > or =5 mg/dl correctly identified three fourths of the intestinal cases. A pH of < or =5 coupled with a bilirubin value of <5 correctly identified more than two thirds of the gastric cases. CONCLUSIONS: Preliminary laboratory-based data indicate that appropriate use of the proposed algorithm could significantly reduce the number of x-rays needed to exclude respiratory placement and to distinguish between gastric and intestinal placement.
BACKGROUND: The purpose of this study was to determine the extent to which pepsin and trypsin concentrations in feeding tube aspirates, in addition to pH, contribute to predicting feeding tube position. METHODS: Aspirates from 742 feeding tubes (nasogastric, n = 343; nasointestinal, n = 399) were tested for pH and enzyme concentrations. Also tested were aspirates from two feeding tubes inadvertently positioned into the lung (one in the pleural space and one in the tracheobronchial tree) and 146 samples of tracheobronchial and pleural fluids collected by other methods. Enzyme assays were conducted in a research laboratory. Results of the pH and enzyme tests were compared with radiologic reports of tube location. RESULTS: Gastric fluid had a mean low pH (4.06), a high mean pepsin concentration (349.1 micrograms/mL), and a low mean trypsin concentration (19.3 micrograms/mL). In contrast, intestinal fluid had a mean high pH (7.40), a high mean trypsin concentration (143.0 micrograms/mL), and a low mean pepsin concentration (24.2 micrograms/mL). Respiratory samples also had a high mean pH (7.89) but contained little or no pepsin or trypsin. Using a logistic regression equation with all three variables to differentiate between respiratory and gastrointestinal placement, it was possible to correctly classify 100% of the respiratory cases and 93.4% of the gastrointestinal cases. Another equation used to differentiate between gastric and intestinal sites was able to classify correctly 91.2% of the gastric cases and 91.5% of the intestinal cases. CONCLUSIONS: The results clearly indicate that laboratory-determined enzyme concentrations in feeding tube aspirates are helpful in predicting tube location. Thus, it is desirable that inexpensive, simple bedside tests be developed so that they can be used in conjunction with pH measurements to help predict tube position.
By means of thin-layer chromatography (TLC), electroantennogram (EAG), gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS) and field tests, (Z)-3-tetradecenyl acetate(Z3-14:Ac), (E)-3-tetradecen-1-ol(E3-14:OH), and (Z)-3-tetradecen-1-ol(Z3-14:OH) at a ratio of 51:39:10 were identified from the female sex pheromone gland extracts of the carpenterworm, Holcocerus insularis Staudinger (Lepidoptera, Cossidae). The average amounts of Z3-14:Ac, E3-14:OH and Z3-14:OH in a single sex pheromone gland of calling moth were 7.29+/-2.72 ng, 5.72+/-2.43 ng and 1.44+/-0.56 ng, respectively. This is the first time that Z3-14:Ac was identified as a component of lepidopteran sex pheromone. Traps baited with rubber septa impregnated with Z3-14:Ac (500 microg/septum) were more effective than the traps baited with virgin female. The addition of the E3-14:OH and Z3-14:OH to rubber septa baited with Z3-14:Ac did not modify H. insularius male attraction, but E3-14:Ac slightly enhanced trap catch.
To determine the relationship of the origins of the celiac artery (CA) and superior mesenteric artery (SMA) to the vertebral bodies, and their distribution in males and females, we examined them quantitatively on the angiograms of 1,591 patients (male 1,003, female 588). Our results showed that the origins of the CA and SMA were highly variable: 14.0% of the CA originated beyond the extent of the lower half of T12 to the upper part of L1, and 24.7% of the SMA originated beyond the level of L1. The origin of the SMA was more variable than that of the CA (p < 0.01). The variation in the origin of the CA was not significantly different (p > 0.05) between males (13.4%) and females (15.1%), but a statistically significant difference (p < 0.01) between males (22.3%) and females (28.7%) was shown for the SMA. The distance between the origin of the two arteries was over 3 cm in six patients (0.4%). Our results provide a valuable reference for clinical practice.
Gene amplification is a common mechanism of proto-oncogene activation and contributes to tumor progression. Analysis of such genetic alterations is relevant to our understanding of tumor genetics and can provide prognostic information for the patients. A rapid, non-radioactive approach based on qdPCR and fluorescent DNA technique was applied for determination of int-2 and c-erbB2 gene amplification and correlated with other prognostic factors in 70 breast cancer samples. ER and PgR were analysed by immunohistochemistry. The mixed template assay showed 96% concordance between calculated and measured gene copy number. int-2 gene and c-erbB2 amplification were both found in 24% of the tumors. The amplification did not correlate with any of the other prognostic factors. 8% of the tumors showed amplification of both genes without significant correlations to any of the other parameters. The fd-PCR assay is a valuable tool for determination of amplification of int-2 and c-erbB2 genes. Therefore, more detailed information about individual tumour biology and outcome may be acquired by this routine assay and probably provide prognostic impact.