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Biomedical subjects

D Chou

Publications and source records attributed to D Chou.

At least 37 records · Page 2Linked to original sources
PubMed1996

Integrating instruments and the laboratory information system.

Significant progress has been made over the last 30 years in the interfacing of automated analytical instruments with laboratory information systems (LIS). Much of the progress has resulted from technology advances in microelectronics, improvements in information systems, implementation of bar code recognition in instruments, and better communications between instrument vendors, LIS vendors, and users. Further improvements, however, should be possible through a more consistent user interface(s), better integration into the laboratory work-flow, and interfaces that allow the LIS to query instruments regarding their internal operating status. These improvements are needed to extract improvements in productivity that are expected from the laboratory.

Clinical Laboratory Information Systems↗
PubMed1996

Internet: road to heaven or hell for the clinical laboratory?

The Internet started as a research project by the Department of Defense Advanced Research Projects Agency for networking computers. Ironically, the networking project now predominantly supports human rather than computer communications. The Internet's growth, estimated at 20% per month, has been fueled by commercial and public perception that it will become an important medium for merchandising, marketing, and advertising. For the clinical laboratory, the Internet provides high-speed communications through e-mail and allows the retrieval of important information held in repositories. All this capability comes at a price, including the need to manage a complex technology and the risk of instrusions on patient privacy.

Clinical Laboratory Information Systems↗
PubMed1995

Cloning of a highly conserved human protein serine-threonine phosphatase gene from the glioma candidate region on chromosome 19q13.3.

Allelic loss studies have suggested that a glioma tumor suppressor gene resides in a 425-kb region of chromosome 19q, telomeric to D19S219 and centromeric to D19S112. Exon amplification of a cosmid contig spanning this region yielded four exons with high homology to a rat protein serine-threonine phosphatase from a cosmid approximately 100 kb telomeric to D19S219. Isolation of a near full-length cDNA from a human fetal brain cDNA library revealed a protein serine-threonine phosphatase with a tetratricopeptide motif, almost identical to human PPP5C (PP5) and highly homologous to rat PPT. Northern blotting demonstrated expression in most tissues, including brain. Primary and cultured gliomas were studied for genetic alterations in this gene using pulsed-field gel electrophoresis, routine Southern blots, and genomic DNA-and RNA-based single-strand conformation polymorphism analysis. Genomic alterations were were not detected in any of the gliomas, and all studied gliomas expressed the gene, suggesting that this phosphatase is not the putative chromosome 19q glioma tumor suppressor gene.

Amino Acid Sequence↗
PubMed1995

Cellular proliferation and infiltration following interstitial irradiation of normal dog brain is altered by an inhibitor of polyamine synthesis.

PURPOSE: The objectives of this study were to quantitatively define proliferative and infiltrative cell responses after focal 125I irradiation of normal brain, and to determine the effects of an intravenous infusion of alpha-difluoromethylornithine (DFMO) on those responses. METHODS AND MATERIALS: Adult beagle dogs were irradiated using high activity 125I sources. Saline (control) or DFMO (150 mg/kg/day) was infused for 18 days starting 2 days before irradiation. At varying times up to 8 weeks after irradiation, brain tissues were collected and the cell responses in and around the focal lesion were quantified. Immunohistochemical stains were used to label astrocytes (GFAP), vascular endothelial cells (Factor VIII), polymorphonuclear leukocytes (PMNs; MAC 387) and cells synthesizing deoxyribonucleic acid (DNA) (BrdU). Cellular responses were quantified using a histomorphometric analysis. RESULTS: After radiation alone, cellular events included a substantial acute inflammatory response followed by increased BrdU labeling and progressive increases in numbers of capillaries and astrocytes. alpha-Difluoromethylornithine treatment significantly affected the measured cell responses. As in controls, an early inflammatory response was measured, but after 2 weeks there were more PMNs/unit area than in controls. The onset of measurable BrdU labeling was delayed in DFMO-treated animals, and the magnitude of labeling was significantly reduced. Increases in astrocyte and vessel numbers/mm2 were observed after a 2-week delay. At the site of implant, astrocytes from DFMO-treated dogs were significantly smaller than those from controls. CONCLUSIONS: There is substantial cell proliferation and infiltration in response to interstitial irradiation of normal brain, and these responses are significantly altered by DFMO treatment. Although the precise mechanisms by which DFMO exerts its effects in this model are not known, the results from this study suggest that modification of radiation injury may be possible by manipulating the response of normal cells to injury.

Analysis of Variance↗
PubMed1995

Chromosome 19q deletions in human gliomas overlap telomeric to D19S219 and may target a 425 kb region centromeric to D19S112.

Chromosome 19q harbors a tumor suppressor gene that is involved in astrocytoma, oligodendroglioma and mixed glioma tumorigenesis. We had previously mapped this gene to an approximately 5 megabase region of chromosome 19q13.2-13.3 between APOC2 and HRC. To narrow the location of this tumor suppressor further, we studied 138 gliomas for loss of allelic heterozygosity at six microsatellite polymorphisms between APOC2 and HRC, including a newly described polymorphism in the ERCC2 gene. Allelic loss occurred in 48 gliomas (35%), including 25 of 41 oligodendroglial tumors (61%). Four cases had proximal breakpoints within the APOC2-HRC region, two telomeric to ERCC2 and two telomeric to D19S219. In addition, one of the latter tumors had an interstitial deletion between D19S219 and D19S112, a distance of only 425 kilobases surrounding the DM (myotonic dystrophy) gene. These findings suggest that the glioma tumor suppressor on chromosome 19q maps to 19q13.3, telomeric to D19S219 and perhaps centromeric to D19S112. The data exclude a number of candidate genes from 19q13.2-13.3, including a putative phosphatase gene and the DNA repair/metabolism genes ERCC1, ERCC2 and probably LIG1.

Base Sequence↗
PubMed1986

Application of the EXPERT consultation system to accelerated laboratory testing and interpretation.

The EXPERT consultation system-building tool, a knowledge-based artificial intelligence program developed at Rutgers University, has been applied to the development of a laboratory consultation system facilitating sequential laboratory testing and interpretation. Depending on the results of a basic panel of laboratory tests, the system requests that specific secondary tests be performed. Input of these secondary findings can result in requests for tertiary testing, to complete the database necessary for interpretation. Interpretation of all results is based upon final inferences from the collected findings through a series of rules, a hierarchical network that yields an efficient production system not easily obtained through conventional programming. The rules included in this model are based upon initial results for total protein, calcium, glucose, total bilirubin, alkaline phosphatase, lactate dehydrogenase, aspartate aminotransferase, thyroxin, hemoglobin, mean corpuscular volume, and the concentrations of four drugs. Pertinent clinical history items included are jaundice, diabetes, thyroid disease, medications, and ethanol. Implementing this system in a laboratory-based accelerated testing program involving outpatients maximized the effective use of laboratory resources, eliminated useless testing, and provided the patient with low-cost laboratory information.

Adolescent↗
PubMed1986

Robotic sample preparation evaluated for the immunochemical determination of cardiac isoenzymes.

A general-purpose bench-top laboratory robot was programmed to perform sample preparation for immunoprecipitative and immunoinhibitory determinations of cardiac isoenzymes with commercial kits. Run size could be varied from 1 to 24 patients' samples, and was determined by the robot without prompting. The robot placed the processed samples into a sample rotor for dried transfer to a batch centrifugal analyzer. Robotic precision compared well with that of manual performance of the same procedures at four concentrations of lactate dehydrogenase (EC 1.1.1.27) isoenzyme 1 activity and at one of two concentrations of creatine kinase (EC 2.7.3.2.) isoenzyme MB activity; for the other creatine kinase MB concentration, use of the robot significantly improved precision. Results for 100 samples from patients after open-heart surgery were highly correlated with manually obtained results for both isoenzyme determinations (r less that 0.96 each). Time to completion for small run sizes for either approach was comparable about 25 min. For larger batches, robotic run time increased rapidly, to 169 min for 24 patients' samples vs 41 min by manual assay.

Autoanalysis↗
PubMed1980

Interference by the 4-hydroxylated metabolite of propranolol with determination of metanephrines by the Pisano method.

Measurements of urinary metanephrines by the Pisano procedure (Clin. Chim. Acta 5: 406, 1960) are unreliable in patients who are taking propranolol owing to the presence of 4-hydroxypropranolol in the urine. Three properties of this propranolol metabolite lead to interference: (a) it is absorbed and eluted from ion-exchange resins under the conditions Pisano used for metanephrine isolation, (b) at high pH it absorbs at 350 to 360 nm, and (c) it is oxidized by periodate to a substance with negligible absorption in this region. Because 350 to 360 nm is the wavelength used to quantitate vanillin, the product formed from periodate oxidation of metanephrines, and because the unoxidized eluate is used as a specimen blank, the presence of 4-hydroxypropranolol spuriously decreases the measured urinary metanephrines; this has special significance because patients being tested for increased metanephrines are also likely to be receiving propranolol for hypertension.

Chromatography, Ion Exchange↗
PubMed1977

Is 2-dimethylaminoethanol (deanol) indeed a precursor of brain acetylcholine? A gas chromatographic evaluation.

Acute administration of deanol-p-acetamidobenzoate (Deaner; deanol) has been reported to elevate brain choline (CH) and acetylcholine (ACh) levels. We have developed a specific and sensitive gas chromatographic assay to measure deanol levels in tissue and have applied this assay to our studies of the effect of acute deanol administration on deanol, ACh and Ch levels in rodent brains. Details of the method are described in this text. This procedure is quantitative and yields reproducible results over a wide range of deanol concentrations (0.30-200 nmol). Seven endogenous and pharmacological parameters have been studied using this procedure. In control rodent brain, liver, heart, lung and plasma, we detected no free endogenous deanol (less than 1 nmol/g). After deanol administration, we were able to detect deanol in tissue and have attempted to determine a relationship between these levels and values of ACh in the same tissue. Regardless of deanol pretreatment time (1-30 minutes) or doses (33.3-3000 mg/kg i.p.) used, we detected no increase in mouse whole brain ACh levels. Likewise, there was no detectable elevation in ACh levels in rat whole brain, cortex, striatum or hippocampus after a 15-minute pretreatment with 550 mg/kg of deanol (i.p.). The only elevation in ACh levels which we detected occurred selectively in the striatum of mice pretreated with a massive dose (900 mg/kg i.p.) of deanol for 30 minutes. This selective increase in striatal ACh levels oculd not, however, be related to levels of deanol in the striatum because there was no greater accumulation of deanol in the striatum than in other brain areas tested or in whole brain. These data do not confirm the results of other investigators who reported elevations in whole brain or striatal ACh levels after acute administration of lower doses of deanol. The data emphasize the need for further investigation into the mode of action of deanol and question its suggested role as an immediate precursor of ACh synthesis in the central nervous system.

Acetylcholine↗
PubMed1974

Penetration of Bdellovibrio bacteriovorus into host cells.

Electron microscopy reveals that, in Bdellovibrio infection, after the formation of a passage pore in the host cell wall, the differentiated parasite penetration pole is associated with the host protoplast. This firm contact persists throughout the parasite penetration and after this process is completed. In penetrated hosts this contact is also apparent by phase microscopy. The association between the walls of the parasite and the host at the passage pore, on the other hand, is transient. Bdellovibrio do not penetrate hosts whose protoplast and cell walls are separated by plasmolysis, or in which the membrane-wall relationship is affected by low turgor pressure. It is concluded, therefore, that for penetration to occur it is essential that the host protoplast be within reach of the parasite, so that a firm contact can be established between them. A penetration mechanism is proposed that is effected by forces generated by fluxes of water and solutes due to structural changes in the infected host envelope. These forces cause a differential expansion of the host protoplast and cell wall and their separation from each other around the entry site, while the parasite remains firmly anchored to the host protoplast. Consequently, the parasite ends up enclosed in the expanded host periplasm. The actual entry, therefore, is a passive act of the parasite.

Bacteria↗