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Lau B, Samant R, E C, Gallant V, Tam T. 2357. Int J Radiat Oncol Biol Phys 2006. [DOI: 10.1016/j.ijrobp.2006.07.766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Lau B, Bretaud S, Huang Y, Lin E, Guo S. Dissociation of food and opiate preference by a genetic mutation in zebrafish. GENES BRAIN AND BEHAVIOR 2006; 5:497-505. [PMID: 17010096 DOI: 10.1111/j.1601-183x.2005.00185.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Both natural rewards and addictive substances have the ability to reinforce behaviors. It has been unclear whether identical neural pathways mediate the actions of both. In addition, little is known about these behaviors and the underlying neural mechanisms in a genetically tractable vertebrate, the zebrafish Danio rerio. Using a conditioned place preference paradigm, we demonstrate that wildtype zebrafish exhibit a robust preference for food as well as the opiate drug morphine that can be blocked by the opioid receptor antagonist naloxone. Moreover, we show that the too few mutant, which disrupts a conserved zinc finger-containing gene and exhibits a reduction of selective groups of dopaminergic and serotonergic neurons in the basal diencephalon, displays normal food preference but shows no preference for morphine. Pretreatment with dopamine receptor antagonists abolishes morphine preference in the wildtype. These studies demonstrate that zebrafish display measurable preference behavior for reward and show that the preference for natural reward and addictive drug is dissociable by a single-gene mutation that alters subregions of brain monoamine neurotransmitter systems. Future genetic analysis in zebrafish shall uncover further molecular and cellular mechanisms underlying the formation and function of neural circuitry that regulate opiate and food preference behavior.
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Wu Y, Lau B, Smith S, Troyan K, Barnett Foster DE. Enteropathogenic Escherichia coli infection triggers host phospholipid metabolism perturbations. Infect Immun 2004; 72:6764-72. [PMID: 15557596 PMCID: PMC529104 DOI: 10.1128/iai.72.12.6764-6772.2004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Enteropathogenic Escherichia coli (EPEC) specifically recognizes phosphatidylethanolamine (PE) on the outer leaflet of host epithelial cells. EPEC also induces apoptosis in epithelial cells, which results in increased levels of outer leaflet PE and increased bacterial binding. Consequently, it is of interest to investigate whether EPEC infection perturbs host cell phospholipid metabolism and whether the changes play a role in the apoptotic signaling. Our findings indicate that EPEC infection results in a significant increase in the epithelial cell PE level and a corresponding decrease in the phosphatidylcholine (PC) level. PE synthesis via both the de novo pathway and the serine decarboxylation pathway was enhanced, and de novo synthesis of phosphatidylcholine via CDP-choline was reduced. The changes were transitory, and the maximum change was noted after 4 to 5 h of infection. Addition of exogenous PC or CDP-choline to epithelial cells prior to infection abrogated EPEC-induced apoptosis, suggesting that EPEC infection inhibits the CTP-phosphocholine cytidylyltransferase step in PC synthesis, which is reportedly inhibited during nonmicrobially induced apoptosis. On the other hand, incorporation of exogenous PE by the host cells enhanced EPEC-induced apoptosis and necrosis without increasing bacterial adhesion. This is the first report that pathogen-induced apoptosis is associated with significant changes in PE and PC metabolism, and the results suggest that EPEC adhesion to a host membrane phospholipid plays a role in disruption of host phospholipid metabolism.
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Sivak O, Lau B, Patankar N, Wasan KM. Unidirectional Inhibition of Lipid Transfer Protein I-Mediated Transfer of Cholesteryl Esters Between High-Density and Low-Density Lipoproteins by Amphotericin B Lipid Complex. Pharm Res 2004; 21:2336-9. [PMID: 15648266 DOI: 10.1007/s11095-004-7686-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
PURPOSE The purpose of this study was to determine whether Fungizone or amphotericin B lipid complex (ABLC; ABELCET) affects the transfer of cholesteryl ester (CE) by lipid transfer protein I (LTP I; also known as cholesteryl ester transfer protein) between HDL and LDL (bidirectional transfer HDL to LDL and LDL to HDL). METHODS Increasing concentrations of either Fungizone or ABELCET (1.25-12.5 microg AmpB/ml) were incubated with HDL and [3H]CE-LDL or [3H]CE-HDL and LDL (the amount of each fraction added was equivalent to 10 microg of cholesterol) and LTP I in delipidated human plasma at 37 degrees C for 90 min. As a positive control, TP2, a monoclonal antibody directed against LTP-1, was added instead of drug. After incubation, manganese and phosphate reagents were then added to precipitate out all of the LDL. The supernatant, consisted of only HDL, was counted for radioactivity to determine the amount of CE transferred from LDL. Similarly, the precipitate consisted of only LDL, was counted for radioactivity to determine the amount of CE transferred from HDL. RESULTS For Fungizone, the transfer of cholesteryl ester (CE) between HDL and LDL were not significantly different compared to nontreated controls. For ABELCET, CE transfer from HDL to LDL was significantly decreased at 12.5 microg AmpB/ml compared to control. However, transfer from LDL to HDL was not significantly different compared to non-treated controls. Similar results were observed with the major lipid component of ABELCET, dimyristoylphosphatidylcholine. CE transfer from HDL to LDL and LDL to HDL was significantly decreased when using the positive control (TP2). CONCLUSIONS Fungizone does not affect LTP I-mediated transfer of CE between HDL and LDL. ABELCET inhibits transfer from HDL to LDL, but has no effect on CE transfer from LDL to HDL. This uni-directional inhibition may contribute to the high recovery of AmpB in HDL but the very low presence of drug in the LDL fraction following ABELCET incubation.
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Bissell D, Burton J, Lau B, Marcolini E. Correlation between plasma B-Type natriuretic peptide and N-Terminal Pro–B-Type natriuretic peptide in dyspneic emergency and hospitalized patients. Ann Emerg Med 2004. [DOI: 10.1016/j.annemergmed.2004.07.245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Hu J, Pang JCS, Tong CYK, Lau B, Yin XL, Poon WS, Jiang CC, Zhou LF, Ng HK. High-resolution genome-wide allelotype analysis identifies loss of chromosome 14q as a recurrent genetic alteration in astrocytic tumours. Br J Cancer 2002; 87:218-24. [PMID: 12107846 PMCID: PMC2376105 DOI: 10.1038/sj.bjc.6600430] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2002] [Revised: 04/23/2002] [Accepted: 05/03/2002] [Indexed: 11/09/2022] Open
Abstract
Diffusely infiltrative astrocytic tumours are the most common neoplasms in the human brain. To localise putative tumour suppressor loci that are involved in low-grade astrocytomas, we performed high-resolution genome-wide allelotype analysis on 17 fibrillary astrocytomas. Non-random allelic losses were identified on chromosomal arms 10p (29%), 10q (29%), 14q (35%), 17p (53%), and 19q (29%), with their respective common regions of deletions delineated at 10p14-15.1, 10q25.1-qter, 14q212.2-qer, 17p11.2-pter and 19q12-13.4. These results suggest that alterations of these chromosomal regions play important roles in the development of astrocytoma. We also allelotyped 21 de novo glioblastoma multiforme with an aim to unveil genetic changes that are common to both types of astrocytic tumours. Non-random allelic losses were identified on 9p (67%), 10p (62%), 10q (76%), 13q (60%), 14q (50%), and 17p (65%). Allelic losses of 10p, 10q, 14q and 17p were common genetic alterations detectable in both fibrillary astrocytomas and glioblastoma multiforme. In addition, two common regions of deletions on chromosome 14 were mapped to 14q22.3-32.1 and 14q32.1-qter, suggesting the presence of two putative tumour suppressor genes. In conclusion, our comprehensive allelotype analysis has unveiled several critical tumour suppressor loci that are involved in the development of fibrillary astrocytomas and glioblastoma multiforme. Although these two types of brain tumours are believed to evolve from different genetic pathways, they do share some common genetic changes. Our results indicate that deletions of chromosome 14q is a recurrent genetic event in the development of astrocytoma and highlight the subchromosomal regions on this chromosome that are likely to contain putative tumour suppressor genes involved in the oncogenesis of astrocytic tumours.
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Abul-Milh M, Wu Y, Lau B, Lingwood CA, Barnett Foster D. Induction of epithelial cell death including apoptosis by enteropathogenic Escherichia coli expressing bundle-forming pili. Infect Immun 2001; 69:7356-64. [PMID: 11705908 PMCID: PMC98822 DOI: 10.1128/iai.69.12.7356-7364.2001] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2001] [Accepted: 09/17/2001] [Indexed: 12/29/2022] Open
Abstract
Infection with enteropathogenic Escherichia coli (EPEC) is a major cause of severe infantile diarrhea, particularly in parts of the developing world. The bundle-forming pilus (BFP) of EPEC is an established virulence factor encoded on the EPEC adherence factor plasmid (EAF) and has been implicated in both localized adherence to host cells and bacterial autoaggregation. We investigated the role of BFP in the ability of EPEC binding to kill host epithelial cells. BFP-expressing strains killed all three cell lines tested, comprising HEp-2 (laryngeal), HeLa (cervical), and Caco-2 (colonic) cells. Analysis of phosphatidylserine expression, internucleosomal cleavage of host cell DNA, and morphological changes detected by electron microscopy indicated evidence of apoptosis. The extent of cell death was significantly greater for BFP-expressing strains, including E2348/69, a wild-type clinical isolate, as well as for a laboratory strain, HB101, transformed with a bfp-carrying plasmid. Strains which did not express BFP induced significantly less cell death, including a bfpA disruptional mutant of E2348/69, EAF plasmid-cured E2348/69, HB101, and HB101 complemented with the locus of enterocyte effacement pathogenicity island. These results indicate a direct correlation between BFP expression and induction of cell death, including apoptosis, an event which may involve the targeting of host cell membrane phosphatidylethanolamine.
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Khursigara C, Abul-Milh M, Lau B, Girón JA, Lingwood CA, Barnett Foster DE. Enteropathogenic Escherichia coli virulence factor bundle-forming pilus has a binding specificity for phosphatidylethanolamine. Infect Immun 2001; 69:6573-9. [PMID: 11598024 PMCID: PMC100029 DOI: 10.1128/iai.69.11.6573-6579.2001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The bundle-forming pilus (BFP) of enteropathogenic Escherichia coli (EPEC), an established virulence factor encoded on the EPEC adherence factor (EAF) plasmid, has been implicated in the formation of bacterial autoaggregates and in the localized adherence of EPEC to cultured epithelial cells. While understanding of the pathogenic mechanism of this organism is rapidly improving, a receptor ligand for BFP has not yet been identified. We now report, using both solid-phase and liposome binding assays, that BFP expression correlates with phosphatidylethanolamine (PE) binding. In a thin-layer chromatogram overlay assay, specific recognition of PE was documented for BFP-expressing strains, including E2348/69, a wild-type EPEC clinical isolate, as well as a laboratory strain, HB101, transformed with a bfp-carrying plasmid. Strains which did not express BFP did not bind PE, including a bfpA disruptional mutant of E2348/69, EAF plasmid-cured E2348/69, and HB101. E2348/69 also aggregated PE-containing liposomes but not phosphatidylcholine- or phosphatidylserine-containing liposomes, while BFP-negative strains did not produce aggregates with any tested liposomes. Purified BFP preparations bound commercial PE standards as well as a PE-containing band within lipid extracts from human epithelial cells and from E2348/69. Our results therefore indicate a specific interaction between BFP and PE and suggest that PE may serve as a BFP receptor for bacterial autoaggregation and may promote localized adherence to host cells, both of which contribute to bacterial pathogenesis.
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Gange SJ, Mellors JW, Lau B, Detels R, Phair JP, Muñoz A, Margolick JB. Longitudinal patterns of HIV type 1 RNA among individuals with late disease progression. AIDS Res Hum Retroviruses 2001; 17:1223-9. [PMID: 11559421 DOI: 10.1089/088922201750461276] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Longitudinal measurements of plasma HIV RNA were analyzed using novel segmented regression models for 62 men in the Multicenter AIDS Cohort Study who at enrollment in 1985 were HIV seropositive and who had stable CD4+ lymphocyte counts and no clinical disease progression for a 6-year period between 1985 and 1991. Through 1996, 20 of the men developed clinical AIDS or died (late progressors) and 42 remained asymptomatic (nonprogressors). Using segmented regression model methods, we estimated, for each individual, the time when a change in HIV RNA trajectory was most likely to have occurred. Prior to this time, late progressors and nonprogressors had stable plasma HIV RNA levels, although the mean level in late progressors was 0.42 log10 copies/ml higher than in nonprogressors (p = 0.018). Furthermore, late progressors showed significant increases in HIV RNA levels of 0.23 log10 copies/ml/year (1.7-fold increase/year). This increase in HIV RNA in the late progressors began approximately 1.1 years prior to the onset of their decline in CD4+ lymphocytes, and 4.8 years prior to the onset of AIDS. These results provide evidence that an increase in the slope of plasma levels of HIV RNA is a sign of incipient progression of HIV disease.
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Lau B. The role of global negative self-evaluations in the influence of body weight on weight and eating concerns. Eat Weight Disord 2001; 6:25-31. [PMID: 11300542 DOI: 10.1007/bf03339748] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The aim of this study was to test a model based on the assumption that a social comparison-process of body mass index could lead to weight and eating concerns by lowering self-evaluation. Three hundred and ninety-five girls from five age cohorts (in grades five through nine at the time of data collection) participated in a questionnaire-based study. Support for a model where global negative self-evaluations played a mediating role was found among the oldest girls who perceived slimness norms among their peers. Among girls not perceiving a norm of thinness, and among younger girls perceiving such a norm, the model found no support. The proposed model gives an explanation of how the dynamic process of social norms of thinness, body weight and self-evaluation, can cause some girls to become concerned about their body weight.
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Abstract
In a sample of Norwegian adolescents (n = 1117) 27, 4% of the girls and 9% of the boys reported that they were dieting. Using multiple regression analyses, we were able to predict 50% of girls dieting behavior and 24% of boys dieting behavior. Psychological concerns relating to weight and eating (WEC) as well as perceptions of feeling fatter than others were the only significant predictors of dieting in girls, whilst dieting in boys could also be predicted by their Body Mass Index. Dieting girls who scored high on the Weight and Eating Concerns Inventory were found to suffer constipation and binge eating attacks more often than other dieting girls. This was taken as an indication that these girls were at risk of developing an eating disorder.
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Abstract
The aim of the present study was to test the properties of an instrument that assesses concerns about weight and eating without reference to dieting behavior. A short instrument, the Weight and Eating Concerns Inventory (WECI) was examined in a sample of 569 boys and 548 girls aged 11 to 15 years. Confirmatory factor analyses with LISREL showed a better fit with a version of the instrument that did not include a reference to dieting behavior, compared to a version that included such a reference. This was true for both boys and girls, irrespective of their age group. However, the results indicated that both versions should be used with caution for young boys. The internal consistency of the WECI (that is, the version without reference to dieting) was satisfactory, ranging from 0.78 to 0.86 for girls and from 0.68 to 0.73 for boys. The WECI correlated quite substantially with negative self-evaluations and depression for boys and girls in all the age groups assessed, suggesting that high scores on the WECI may indicate a problem that goes beyond worries or concerns, and should be taken seriously. In general, girls reported more of these concerns than boys, and the correlation between the WECI and dieting was stronger among girls compared to boys.
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Kömüves LG, Shen WF, Kwong A, Stelnicki E, Rozenfeld S, Oda Y, Blink A, Krishnan K, Lau B, Mauro T, Largman C. Changes in HOXB6 homeodomain protein structure and localization during human epidermal development and differentiation. Dev Dyn 2000; 218:636-47. [PMID: 10906782 DOI: 10.1002/1097-0177(2000)9999:9999<::aid-dvdy1014>3.0.co;2-i] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
HOX homeodomain proteins are master developmental regulators, which are now thought to function as transcription factors by forming cooperative DNA binding complexes with PBX or other protein partners. Although PBX proteins exhibit regulated subcellular localization and function in the nucleus in other tissues, little data exists on HOX and PBX protein localization during skin development. We now show that the HOXB6 protein is expressed in the suprabasal layer of the early developing epidermis and throughout the upper layers of late fetal and adult human skin. HOXB6 signal is cytoplasmic throughout fetal epidermal development, but substantially nuclear in normal adult skin. HOXB6 protein is also partially nuclear in hyperproliferative skin conditions, but appears to be cytoplasmic in basal and squamous cell carcinomas. Although all three PBX genes are expressed in fetal epidermis, none of the three PBX proteins exhibit nuclear co-localization with HOXB6 in either fetal or adult epidermis. RNA and protein data suggest that a truncated HOXB6 protein, lacking the homeodomain, is expressed in undifferentiated keratinocytes and that the full-length protein is induced by differentiation. GFP-fusion proteins were used to demonstrate that the full-length HOXB6 protein is localized to the nucleus while the truncated protein is largely cytoplasmic. Taken together, these data suggest that during epidermal development the truncated HOXB6 isoform may function by a mechanism other than as DNA binding protein, and that most of the nuclear, homeodomain-containing HOXB6 protein does not utilize PBX proteins as DNA binding partners in the skin. Published 2000 Wiley-Liss, Inc.
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Anastos K, Gange SJ, Lau B, Weiser B, Detels R, Giorgi JV, Margolick JB, Cohen M, Phair J, Melnick S, Rinaldo CR, Kovacs A, Levine A, Landesman S, Young M, Muñoz A, Greenblatt RM. Association of race and gender with HIV-1 RNA levels and immunologic progression. J Acquir Immune Defic Syndr 2000; 24:218-26. [PMID: 10969345 DOI: 10.1097/00126334-200007010-00004] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
CONTEXT HIV-1 RNA and lymphocyte subset levels are the principal indications for antiretroviral treatment. Past reports have differed with regard to the effect of gender and race on these measures and in measures of disease progression. OBJECTIVE To assess racial and gender differences in HIV-1 RNA levels and CD4+ lymphocyte decline. DESIGN A longitudinal study based in the two largest HIV natural history cohort studies conducted in 7 metropolitan areas of the United States. RESULTS In all, 1256 adult women and 1603 adult men for whom multiple data points were available prior to initiation of antiretroviral therapy were included. Women were more likely to be nonwhite, to have a history of injection drug use, and to have HIV-associated symptoms. After adjustment for differences in measurement method, baseline CD4+ cell count, age, and clinical symptoms, HIV-1 RNA levels were 32% to 50% lower in women than in men at CD4+ counts >200 cells/mm3 (p <.001) but not at CD4+ cell counts <200 cells/mm3. HIV-1 RNA levels were also 41% lower in nonwhites than in whites (p <.001) and 21% lower in persons reporting a prior history of injection drug use (p <.001). Women had more rapid declines in CD4+ cell counts over time than men (difference in slope of 46 cells/year) and nonwhite individuals had slower decline in CD4 cell counts than whites (difference of 39 cells/year). CONCLUSIONS Both race and gender influence the values of HIV-1 RNA and the rate of HIV-1 disease progression as indicated by decline in CD4 cell counts over time. These effects could provide clues regarding the factors that influence HIV-disease progression and may indicate that guidelines for therapy should be adjusted for demographic characteristics.
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Lau B. Global negative self-evaluations, weight and eating concerns and depressive symptoms: a prospective study of adolescents. Eat Weight Disord 2000; 5:7-15. [PMID: 10840651 DOI: 10.1007/bf03353432] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
A longitudinal study with four sequential cohorts of girls and boys in early to mid-adolescence (n = 607) was used to assess adolescent changes in global negative self-evaluation, depressive symptoms and weight and eating concerns. The effects of these areas on one another over time were also assessed. Over the six months between the two data collection times, both the girls and the boys experienced an improvement in depressive symptoms, while the boys also experienced a decrease in weight concerns. The results indicated that global negative self-evaluations could predict weight and eating concerns in boys and girls, while weight concerns could predict depressive symptoms in girls. These results are of particular interest, since these relationships have not been previously examined in a longitudinal study.
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Lau B, Macdonald PM. Determination of the pKa of membrane-bound N,N-dimethylsphingosine using deuterium NMR spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1237:37-42. [PMID: 7619840 DOI: 10.1016/0005-2736(95)00083-f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Deuterium nuclear magnetic resonance (2H-NMR) spectroscopy was applied to determine the pKa of the protein kinase C (PKC) inhibitor, N,N-dimethylsphingosine (DMS), when bound to lipid bilayers composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). The quadrupolar splittings from the deuterium labels at the alpha- and the beta-choline positions of the headgroup of POPC responded to the presence of DMS in a manner indicative of an accumulation of cationic charges near the surface plane occupied by the phospholipid phosphate group. Both quadrupolar splittings varied linearly with the amount of added DMS at pH 7.0. Conversely, at pH 10.0 DMS had virtually no influence on either quadrupole splitting, an effect attributed to titration of the dimethyl amino group of DMS to its neutral form. A DMS titration curve was obtained by quantifying the change in the quadrupolar splittings as a function of pH. The pKa of membrane-bound DMS was extracted from this 2H-NMR data by simulating the quadrupole splitting-titration curve for different values of the pKa, yielding a pKa of 8.8 after non-linear least squares fitting.
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Hamel E, Grégoire L, Lau B. 5-HT1 receptors mediating contraction in bovine cerebral arteries: a model for human cerebrovascular '5-HT1D beta' receptors. Eur J Pharmacol 1993; 242:75-82. [PMID: 8223939 DOI: 10.1016/0014-2999(93)90012-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We report on the pharmacological profile of the 5-HT receptor which induces contraction of the bovine isolated cerebral arteries. Several 5-HT receptor agonists were tested for their ability to induce vasoconstriction in bovine pial arteries and their potencies were compared to that of 5-HT. The rank order of agonist potency can be summarized as 5-carboxamidotryptamine (5-CT) = RU 24969 > or = 5-HT > sumatriptan > alpha-methyl-5-HT > methysergide > 2-methyl-5-HT > ((+-)-2-dipropylamino-8-hydroxy-1,2,3,4-tetrahydronaphthalene (8-OH-DPAT). Only methysergide induced a contraction which was smaller than that elicited by 5-HT. Antagonists with selective affinity at 5-HT1A/1B (propranolol), 5-HT1C (mesulergine), 5-HT2 (ketanserin, mianserin) and 5-HT3 (MDL 72222) sites were inactive to block the 5-HT-induced contraction. In contrast, the 5-HT1/5-HT2 receptor antagonists methiothepin and metergoline inhibited the 5-HT-induced response with relatively high affinity (pA2 = 8.16 +/- 0.26 and 6.73 +/- 0.05, respectively). Overall, this pharmacological profile indicated clearly that a 5-HT1 receptor, most closely related to the 5-HT1D subtype, is responsible for the 5-HT-induced contraction of bovine cerebral arteries. Correlation analysis of the potencies of a series of 5-HT receptor agonists and antagonists in bovine and human cerebrovascular preparations showed a highly significant positive correlation (r = 0.94, P = 0.0051).(ABSTRACT TRUNCATED AT 250 WORDS)
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Kreuttner A, Lau B, Mann L, Mattes E, Miller R, Stuber M, Stocker K. Holographic interferometry for the display of shock wave induced deformations and vibrations—A contribution to laser lithotripsy. Lasers Med Sci 1993. [DOI: 10.1007/bf02547878] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Lau B, Mattes E. Compact holographic camera without vibration insulation using a 670-nm semiconductor laser. APPLIED OPTICS 1992; 31:4738-4741. [PMID: 20725486 DOI: 10.1364/ao.31.004738] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A compact camera for holography and holographic interferometry is presented. Owing to its simple and rigid construction, vibration insulation is not necessary. The use of a semiconductor laser with a wavelength of 670 nm permits the use of common holographic recording materials. The only optical components of this camera are a beam splitter and a deflection mirror. As an example of the application of this camera, holographic surface contouring is demonstrated.
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Beetke E, Wenzel B, Lau B, Bienengräber V. [Direct capping of the artificial exposed pulp in teeth with deep caries]. STOMATOLOGIE DER DDR 1990; 40:246-9. [PMID: 2270589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We carried out clinical and histological investigations on teeth with superficial and deep caries in which we made an artificial exposure of the pulp to check the reactivity of the endodont. After one year we observed using clinical and x-ray methods successful treatment in 93.4% of the teeth. Histologically the number of successful treatment was 100.0% in teeth with superficial caries and 80.0% in teeth with deep caries.
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Abstract
Oxidative photosensitization was used to characterize the conformational-dependent reactivity of various structures formed by oligonucleotides 14-15 nucleotides in length. The rate and product composition from a single hit process was analyzed using quantitative ion exchange chromatography under native and denaturing conditions. The primary damage incurred under aerobic acetone sensitization was base oxidation that, in turn, would induce strand scission upon a secondary treatment with piperidine. The reactive intermediates of this process were not consistent with diffusible radical species or singlet oxygen, as indicated by isotope and quenching studies. Derivatization was most likely initiated through a type I photoprocess with a direct interaction between DNA bases and excited state acetone preceding an irreversible oxidation step. This dominant reaction demonstrated no obvious sequence or site specificity for initial modification; the relative reactivity among the oligonucleotides did not correspond to any simple trend of base composition or near neighbor analysis. Likewise, the steric requirements of base modification allowed for similar rates of oxidation for single-strand, helical, and aberrant forms of DNA. Hybridization of the most reactive oligonucleotides, however, did suppress their relative single-strand vs double-strand reactivity by as much as fourfold.
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Bailey A, Lau B, Watson ID, Stewart MJ. Determination of ephedrine bioavailability. Clin Chem 1988; 34:427-8. [PMID: 3342527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Lau B, Jäger G, Lippl U. Myelo-monocytic differentiation potential of the CALLA-positive Nalm 6M1 cell line. Eur J Haematol 1987; 38:156-61. [PMID: 2954849 DOI: 10.1111/j.1600-0609.1987.tb01155.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Nalm 6M1 cells, derived from an acute lymphoblastic leukemia of the non-T, non-B type, are known to possess characteristics of early B-lymphocytes. In order to determine whether these cells are able to differentiate along the granulocyte-monocyte pathway, they were cultured in diffusion chambers, and classified according to morphological, cytochemical and immunological criteria. On the basis of this characterization, Nalm 6M1 cells positively labeling with monoclonal anti-human granulocyte or monocyte-specific antibodies were observed in all cases. These immunological changes were accompanied by the appearance of cells positive for the naphthyl-AS-D-chloroacetate esterase reaction. However, no changes in the blast-like appearance of the cultured cells were seen. From these data, we conclude that Nalm 6M1 cells already committed to the B-cell lineage retain their capacity to develop cellular markers of the granulocyte-monocyte series.
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Dörmer P, Ucci G, Lau B, Haas RJ, Janka GE. In vivo production of childhood acute lymphoblastic leukemia cells in relation to ploidy and immunological subtype. Leuk Res 1984; 8:587-95. [PMID: 6332241 DOI: 10.1016/0145-2126(84)90007-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Eighteen pretreatment cases of acute lymphoblastic leukemia (ALL) in children were investigated by quantitative autoradiography in order to determine the labeling index (LI) as well as the DNA synthesis time (ts). The ploidy of the leukemic blasts was evaluated by Feulgen-microphotometry. The group consisted of 12 cases expressing the common ALL (CALL) antigen only, while 6 showed varying degrees of development along the T-cell axis. The latter subgroup was taken together and termed T-ALL for the sake of simplicity. By dividing LI by ts the fractional birth rate (FBR) was derived representing the percentage of the total leukemic cell mass newly formed per unit of time. The present study confirms a previous investigation in which a higher LI was detected in association with hyperdiploidy. It shows that ts is simultaneously prolonged, while the DNA synthesis rate remains unchanged. This proves that in hyperdiploid cases the longer ts is caused by a larger amount of DNA to be synthesized. The FBR is the same for eu- and hyperdiploid, as well as for CALL and T-ALL cases, and there is no correlation between the FBR and the white blood cell count. So far, ALL is the only type of leukemia in which a prolongation of ts has been demonstrated in comparison to normal human lymphatic cells. This prolongation is not caused primarily by differences in ploidy. The type of growth is accumulative, since the relative rate of cell production is lower than normal. As a finding of practical importance, the labeling index is shown to correlate quite closely with the FBR. In this cell system the LI can thus be used as a parameter reflecting the rate of relative cell production.
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