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J Thompson

Publications and source records attributed to J Thompson.

At least 91 records · Page 5Linked to original sources
PubMed2000

Spin correlation in t&tmacr; production from p&pmacr; collisions at radicals = 1.8 TeV

The D0 collaboration has performed a study of spin correlation in t&tmacr; production for the process t&tmacr;-->bW(+)&bmacr;W-, where the W bosons decay to enu or &mgr;nu. A sample of six events was collected during an exposure of the D0 detector to an integrated luminosity of approximately 125 pb(-1) of sqrt[s] = 1.8 TeV p&pmacr; collisions. The standard model (SM) predicts that the short lifetime of the top quark ensures the transmission of any spin information at production to the t&tmacr; decay products. The degree of spin correlation is characterized by a correlation coefficient kappa. We find that kappa>-0.25 at the 68% confidence level, in agreement with the SM prediction of kappa = 0.88.

Journal Article↗
PubMed2000

A transgenic mouse line that develops early-onset invasive gastric carcinoma provides a model for carcinoembryonic antigen-targeted tumor therapy.

In an attempt to obtain suitable in vivo models for optimizing new tumor therapy strategies for intestinal adenocarcinomas, carcinoembryonic antigen (CEA) promoter/SV40 T antigen gene constructs have been used to generate transgenic mice. One transgenic line (L5496), which contains a 424-bp CEA promoter/SV40 T antigen transgene, exclusively developed multi-focal carcinomas in the pyloric region of the stomach in 100% of the offspring. Tumors were already observable in 37-day-old animals as dysplastic cell foci within the mucosal layer. In 50-day-old mice, the tumor mass was mainly restricted to the mucosa with invasive growth into the submucosal tissue. The animals became moribund at 100-130 days of age due to blockage of the pylorus. At this time, the tumor had penetrated into the duodenum and had invaded all tissue layers within the stomach. In contrast to most other stomach tumor models, this one perfectly matches the development of the most common stomach cancers found in humans. Furthermore, after crossing these mice with mice that are transgenic for the human CEA gene, the double transgenic offspring revealed expression of CEA in the resulting tumors. Thus, as well as being a model for studying gastric carcinoma development and prevention, this system should provide a useful preclinical model for CEA-targeted gastric tumor therapy.

Animals↗
PubMed2000

Isolated photon cross section in p&pmacr; collisions at radicals = 1. 8 TeV

We report a new measurement of the cross section for the production of isolated photons with transverse energies ( E(gamma)(T)) above 10 GeV and pseudorapidities |eta|<2.5 in p&pmacr; collisions at sqrt[s] = 1.8 TeV. The results are based on a data sample of 107.6 pb(-1) recorded during 1992-1995 with the D0 detector at the Fermilab Tevatron collider. The background, predominantly from jets which fragment to neutral mesons, was estimated using the longitudinal shower shape of photon candidates in the calorimeter. The measured cross section is in good agreement with the next-to-leading order QCD calculation for E(gamma)(T) greater, similar36 GeV.

Journal Article↗
PubMed2000

Search for second-generation leptoquark pairs in &pmacr;p collisions at radicals = 1.8 TeV

We have searched for second-generation leptoquark (LQ) pairs in the &mgr;&mgr;+jets channel using 94+/-5 pb(-1) of &pmacr;p collider data collected by the D0 experiment at the Fermilab Tevatron during 1993-1996. No evidence for a signal is observed. These results are combined with those from the &mgr;nu+jets and nunu+jets channels to obtain 95% confidence level (C.L.) upper limits on the LQ pair production cross section as a function of mass and beta, the branching fraction of a LQ decay into a charged lepton and a quark. Lower limits of 200(180) GeV/c(2) for beta = 1(1 / 2) are set at the 95% C.L. on the mass of scalar LQ. Mass limits are also set on vector leptoquarks as a function of beta.

Journal Article↗
PubMed2000

Measurement of the W boson mass using electrons at large rapidities

We report a measurement of the W boson mass based on an integrated luminosity of 82 pb(-1) from p&pmacr; collisions at sqrt[s] = 1.8 TeV recorded in 1994-1995 by the D0 detector at the Fermilab Tevatron. We identify W bosons by their decays to enu, where the electron is detected in the forward calorimeters. We extract the mass by fitting the transverse mass and the electron and neutrino transverse momentum spectra of 11 089 W boson candidates. We measure M(W) = 80.691+/-0.227 GeV. By combining this measurement with our previously published central calorimeter results from data taken in 1992-1993 and 1994-1995, we obtain M(W) = 80.482+/-0.091 GeV.

Journal Article↗
PubMed2000

Expression of an anti-CD3 single-chain immunotoxin with a truncated diphtheria toxin in a mutant CHO cell line.

ADP-ribosylating immunotoxins are generally expressed in Escherichia coli and then refolded in vitro. Because the efficiency of the in vitro refolding process decreases with the number of protein domains and internal disulfide bonds, these immunotoxins have been generally limited to single-chain monovalent structures. We now show that using the hamster cell line CHO K1 RE1.22c (J. M. Moehring and T. J. Moehring, 1979, Somat. Cell Genet. 5, 453-468) that has been mutated to ADP-ribosylation insensitivity, a level of 4 microg/ml of a truncated anti-T cell immunotoxin, DT390-scFvUCHT1, can be secreted into the medium. This immunotoxin is glycosylated at the two potential N-linked glycosylation sites in the toxin moiety: positions 16-18 in the A chain and residues 235-237 in the B chain. The glycosylated immunotoxin is relatively nontoxic (IC(50) 4.8 x 10(-10) M). Removal of the N-linked oligosaccharides by N-glycosidase F treatment or mutations at the two N-linked glycosylation sites results in a highly active immunotoxin with an IC(50) of 4 x 10(-12) M toward CD3(+) Jurkat cells. This is a 12-fold increase in toxicity over the same immunotoxin harvested from E. coli periplasm without refolding. A single Asn(235) Ala mutation that removed the B chain glycosylation was nearly as toxic as the double mutant. This suggests that B chain glycosylation is the major cause for the loss of toxicity.

Animals↗
PubMed2000

Strong immunostaining for myogenin in rhabdomyosarcoma is significantly associated with tumors of the alveolar subclass.

Rhabdomyosarcomas are a heterogeneous group of tumors with respect to their molecular basis, degree of differentiation, histology, and clinical behavior. Because of the wide variation of tumor morphology, it is often difficult to distinguish between the distinct subtypes of rhabdomyosarcomas. By using cryosections of tumor specimens and immunohistochemistry, in the present study we show that strong expression of myogenin in rhabdomyosarcoma is associated with alveolar histology (P = <0.0001, Fisher's exact test). Although staining for myogenin was observed in 22 of 26 rhabdomyosarcomas, all alveolar rhabdomyosarcomas (nine of nine) showed high levels of staining for myogenin, as defined by the frequency and intensity of staining of the tumor cells. The staining pattern suggests that the tumor cells are clonally derived from myogenin-positive progenitor cells. In contrast, most embryonal rhabdomyosarcomas (13 of 15) were either negative or showed a low level of staining for myogenin. In these tumors a larger proportion of tumor cells were distinctly negative for myogenin. Six of seven alveolar rhabdomyosarcomas that strongly stained for myogenin were also positive for Pax3-7/Forkhead (FKHR) by polymerase chain reaction/reverse transcriptase-polymerase chain reaction. One of two embryonal rhabdomyosarcomas that strongly stained for myogenin was retrospectively found to be positive for Pax3/FKHR transcripts. Quantitative analysis for myogenin by Western blotting using a smaller subset of rhabdomyosarcomas revealed that in general there was a good correlation between immunohistochemical staining and Western blotting (P = 0.01, Pearson Correlation), although the former technique was more sensitive for detecting tumors with low levels of the protein. On average, alveolar rhabdomyosarcomas expressed at least threefold more myogenin than embryonal rhabdomyosarcomas. Our data show that staining for myogenin will be a simple, rapid, and accurate adjunct for distinguishing between alveolar and embryonal rhabdomyosarcomas. We propose that embryonal rhabdomyosarcomas result from an early block in myogenesis, before the expression of myogenin. In contrast, we propose that alveolar rhabdomyosarcomas either originate from a late block in myogenesis (after expression of myogenin) or that the pathological mechanisms involved in these neoplasms also induce strong expression of this protein.

Antibodies, Monoclonal↗
PubMed2000

Carcinoembryonic antigen family members CEACAM6 and CEACAM7 are differentially expressed in normal tissues and oppositely deregulated in hyperplastic colorectal polyps and early adenomas.

Four members of the carcinoembryonic antigen (CEA) family, CEA, CEACAM1 (BGP), CEACAM6 (NCA-50/90), and CEACAM7 (CGM2), are coexpressed in normal colorectal epithelia but are deregulated in colorectal cancers, where they could play a role in tumorigenesis. As a basis for functional studies, their expression patterns in normal tissues first need to be clarified. This is well documented for CEACAM1 and CEA but not for CEACAM6 or CEACAM7. We have now carried out immunohistochemical expression studies on 35 different organs, using CEACAM6-specific (9A6) and CEACAM7-specific (BAC2) monoclonal antibodies. CEACAM7 was only found on the apical surface of highly differentiated epithelial cells in the colorectal mucosa and on isolated ductal epithelial cells within the pancreas. CEACAM6 was expressed in granulocytes and epithelia from various organs. CEACAM6 and CEACAM7 expression correlated with apoptosis at the table region of the normal colon, and both were absent from highly proliferating cells at the base of colonic crypts. CEACAM6 revealed a broader expression zone in proliferating cells in hyperplastic polyps and adenomas compared with normal mucosa, whereas CEACAM7 was completely absent. Down-regulation of CEACAM7 and up-regulation of CEACAM6 expression in hyperplastic polyps and early adenomas represent some of the earliest observable molecular events leading to colorectal tumors.

Adenoma↗
PubMed2000

Properties and crystal structure of a beta-barrel folding mutant.

A mutant of a beta-barrel protein, rat intestinal fatty acid binding protein, was predicted to be more stable than the wild-type protein due to a novel hydrogen bond. Equilibrium denaturation studies indicated the opposite: the V60N mutant protein was less stable. The folding transitions followed by CD and fluorescence were reversible and two-state for both mutant and wild-type protein. However, the rates of denaturation and renaturation of V60N were faster. During unfolding, the initial rate was associated with 75-80% of the fluorescence and all of the CD amplitude change. A subsequent rate accounted for the remaining fluorescence change for both proteins; thus the intermediate state lacked secondary structure. During folding, one rate was detected by both fluorescence and CD after an initial burst phase for both wild-type and mutant. An additional slower folding rate was detected by fluorescence for the mutant protein. The structure of the V60N mutant has been obtained and is nearly identical to prior crystal structures of IFABP. Analysis of mean differences in hydrogen bond and van der Waals interactions did not readily account for the stability loss due to the mutation. However, significant average differences of the solvent accessible surface and crystallographic displacement factors suggest entropic destabilization.

Animals↗
PubMed2000

Electrostatic interaction between charybdotoxin and a tetrameric mutant of Shaker K(+) channels.

The scorpion toxin, Charybdotoxin (CTX), blocks homotetrameric, voltage-gated K(+) channels by binding near the outer entrance to the pore in one of four indistinguishable orientations. We have determined the pH-dependence of CTX block of a tetrameric Shaker potassium channel with a single copy of a histidine replacing the wild-type phenylalanine at position 425. We compared this pH-dependence with that from homotetrameric channels with four copies of the mutation. We found that protonation of a single amino acid at position 425 had a large effect on the affinity of the channel for CTX-much larger than expected if only one of the four CTX binding orientations was disrupted. The pK(a) for the H(+)-ion induced protection from CTX block indicates that the electrostatic environment near position 425 is likely basic in nature, perhaps because of the proximity of lysine 427. We also examined the pH-dependence of block of channels with one and four copies of the histidine mutation by CTX containing neutralizing mutations of four basic residues on the active face of the toxin. The results suggested an orientation of CTX on the channel that places three of the positively charged CTX residues very near three of the four Shaker 425 positions.

Animals↗
PubMed2000

Recruitment strategies in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial: the first six years.

The Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial has a total enrollment goal of almost 150,000 participants. These participants are being recruited at ten screening centers across the United States. All screening centers tested recruitment methodologies during a 1-year pilot phase. The main phase of recruitment was planned to take place over a 3-year period. The majority of participants are being recruited during the main phase of the study. Each of the screening centers tailors recruitment to its individual catchment area. Recruitment strategies in the PLCO trial are described. As the trial began, several protocol changes were made to help to increase enrollment. The National Cancer Institute (NCI) initiated recruitment efforts at the national level. The individual screening centers describe some of the specific recruitment experiences encountered. As the study progressed, the NCI implemented special initiatives to increase the enrollment of minority participants.

Aged↗
PubMed2000

Assessment of gastric electrical activity and autonomic function among diabetic and nondiabetic patients with symptoms of gastroesophageal reflux.

Gastroesophageal reflux disease (GERD) may present differently in patients with diabetes mellitus (DM) than in nondiabetics (NDM). We compared three tests in two patient groups with GERD symptoms: a DM group (n = 10) and a NDM group (n = 13). The tests were 24-hr esophageal pH, autonomic function testing (AFT), and electrogastrography (EGG). Analysis of the 23 patients revealed the DM group had normal 24-hr pH values (9 of 10 patients, mean pH 3.1 +/- 1.7), while NDM displayed abnormal pH values (9 of 13 patients, mean pH 21.2 +/- 5.9). AFT results were abnormal in DM (demonstrating cholinergic/ adrenergic dysfunction), but normal in NDM. EGG values were abnormal in both groups (mean 3.31 +/- 0.1 in each). We conclude that in GERD-symptomatic patients, those with DM frequently have normal 24-hr pH, but abnormal autonomic functioning, in contrast to NDM, who have abnormal 24-hr pH but normal autonomic function. Both groups had identically abnormal mean EGG values.

Autonomic Nervous System↗
PubMed2000

Molecular, serological and genetic studies on two new HLA-DRB1 alleles--HLA-DRB1*0704 and HLA-DRB1*1507.

Two new HLA-DRB1 alleles (DRB1*0704 and DRB1*1507) were detected during routine polymerase chain reaction (PCR)-based typing of two Caucasoid bone marrow panel donors due to apparent DRB1* "blanks" being associated with unexpected DRB4, DRB5 and DQB1 alleles. HLA-DRB1*0704 differed from DRB1*0701 by five consecutive nucleotides at positions 217 to 221 of exon 2 encoding two amino acids substitutions of tyrosine to asparagine at codons 77 and valine to tyrosine at codon 78. DRB1*1507 differed from DRB1*1501 by a single nucleotide at position 127 encoding an amino acid substitution of phenylalanine to tyrosine at codon 47. Their specificities were unequivocally assigned by serology as HLA-DR7 and DR15, respectively, and family and population studies allowed their likely HLA-A,B,C,DR,DQ and complement (Bf, C4A, C4B) bearing haplotypes to be identified. No further examples were found in 19,113 HLA-DR,DQ typed donors from the Welsh Bone Marrow Donor Registry indicating that both these alleles have a phenotype frequency of <0.01% and a gene frequency of <0.00003.

Alleles↗
PubMed2000

Assessment and documentation of bowel care management in palliative care: incorporating patient preferences into the care regimen.

Nurses in a palliative care unit (PCU) recognized that there were several inconsistencies relating to assessment and documentation of patient preferences in bowel care management. Although bowel care is recognized as of key importance to the wellbeing of palliative care patients, there is little evidence in current literature about accommodation of patient preferences in bowel care management. A questionnaire was developed to assess whether patient preferences were elicited on admission to the PCU, were documented, and were included in the bowel care regimen. Data were collected from 100 patients in two PCUs in Australia. The findings suggested that little was assessed or documented about bowel care management on admission except functional or pharmacological information. According to patients in the study, their preferences were seldom incorporated into the bowel care regimen. Lack of documentation of bowel care preferences was also found following an audit of patient notes. Techniques for eliciting information, awareness of alternative or complementary methods of bowel care and better documentation procedures are all recommended for inclusion in nursing practice in the palliative care setting.

Adult↗