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Grunau B, Tom J, Asamoah-Boaheng M, O’Brien SF, Drews SJ, Sediqi S, Lavoie PM, Barakauskas V, Goldfarb DM. Sensitivity of the Elecsys Nucleocapsid Assay for the Detection of Preceding SARS-CoV-2 Infections. Open Forum Infect Dis 2022; 9:ofac349. [PMID: 35937649 PMCID: PMC9350617 DOI: 10.1093/ofid/ofac349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 07/24/2022] [Indexed: 11/26/2022] Open
Abstract
Nucleocapsid serological assay sensitivity to identify severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections among vaccinees and for Omicron cases is unclear. In this prospective study, the Elecsys nucleocapsid assay was 89% sensitive in identifying SARS-CoV-2 infections 14–607 days pre–blood collection. Sensitivity was similar when comparing by vaccination status, and in Omicron (vs pre-Omicron) cases.
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Affiliation(s)
- Brian Grunau
- Centre for Health Evaluation & Outcome Sciences, St. Paul’s Hospital , Vancouver , Canada
- Department of Emergency Medicine, University of British Columbia , Vancouver , Canada
- British Columbia Emergency Health Services , Vancouver, British Columbia , Canada
| | - Janessa Tom
- British Columbia Emergency Health Services , Vancouver, British Columbia , Canada
| | - Michael Asamoah-Boaheng
- Department of Emergency Medicine, University of British Columbia , Vancouver , Canada
- Faculty of Medicine, Memorial University of Newfoundland , St. John’s , Canada
| | | | - Steven J Drews
- Canadian Blood Services , Ottawa , Canada
- Laboratory Medicine and Pathology, University of Alberta , Edmonton , Canada
| | - Sadaf Sediqi
- Department of Pathology and Laboratory Medicine, University of British Columbia , Vancouver , Canada
| | - Pascal M Lavoie
- Department of Pediatrics, University of British Columbia , Vancouver , Canada
| | - Vilte Barakauskas
- Department of Pathology and Laboratory Medicine, University of British Columbia , Vancouver , Canada
| | - David M Goldfarb
- Department of Pathology and Laboratory Medicine, University of British Columbia , Vancouver , Canada
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Burch JB, Tom J, Zhai Y, Criswell L, Leo E, Ogoussan K. Shiftwork impacts and adaptation among health care workers. Occup Med (Lond) 2009; 59:159-66. [DOI: 10.1093/occmed/kqp015] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Lim D, Seliktar R, Farrell E, Tom J, Nunes L, Sun W, Wee J. Loading conditions and bone formation in the GH region of the shoulder. Conf Proc IEEE Eng Med Biol Soc 2007; 2004:5092-5. [PMID: 17271463 DOI: 10.1109/iembs.2004.1404407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The present study investigates how loading of the shoulder effect the formation of the trabeculae in the subarticular region of the gleno-humeral joint. Bone morphology was determined from scapular cadaveric specimens and finite element (FE) analysis was employed to analyse principal stress trajectories. Boundary conditions corresponded to five functional activities were considered. The results show deviations of the computed trajectories from actual trabecular lines obtained from the bone specimens ranged on average from 10% to 17%. Each activity produced different regional deviation corresponding to the specific loading condition. This study concludes that certain loading conditions are more significant in explaining the formation of the trabecular architecture. The results also suggest that due to the extra sensitivity of the front and the rear aspects of the "lateral region" to the loading conditions, these regions may be more indicative in reflecting shoulder injuries.
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Affiliation(s)
- D Lim
- School of Biomed. Engineering, Drexel University, Philadelphia, PA, USA
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Abstract
Progeny from self-pollinations and intrapopulation crosses were examined in Schiedea viscosa to determine the extent of inbreeding depression in this highly selfing species. Progeny of interpopulation crosses were also investigated to determine whether deleterious alleles have been fixed in populations of S. viscosa. There was no inbreeding depression at early life history stages, including seeds per capsule, seed mass, or germination. Inbreeding depression was detected for the later life history stage of fruit biomass, although not for survival or life span. Heterosis for vegetative biomass and fruit biomass was detected in progeny from crosses between populations. Levels of inbreeding depression in S. viscosa are low relative to out-crossing species of Schiedea, especially when early life history stages are compared.
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Affiliation(s)
- S G Weller
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697, USA.
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Tom J, Forrest W, Chang RK. 391 FACTORS AFFECTING OXYGEN PULSE IN CHILDREN DURING CARDIOPULMONARY EXERCISE TESTING. J Investig Med 2005. [DOI: 10.2310/6650.2005.00005.390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Medintz IL, Berti L, Emrich CA, Tom J, Scherer JR, Mathies RA. Genotyping energy-transfer-cassette-labeled short-tandem-repeat amplicons with capillary array electrophoresis microchannel plates. Clin Chem 2001; 47:1614-21. [PMID: 11514394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
BACKGROUND Genetic analysis of microsatellite DNA is a powerful tool used in linkage analysis, gene mapping, and clinical diagnosis. To address the expanding needs of studies of short tandem repeats (STRs), we demonstrated high-performance STR analysis on a high-throughput microchannel plate-based platform. METHODS Energy-transfer-cassette-labeled STR amplicons were separated and typed on a microfabricated 96-channel radial capillary array electrophoresis (CAE) microchannel plate system. Four-color detection was accomplished with a laser-excited confocal fluorescence rotary scanner. RESULTS Multiplex STR analysis with single base-pair resolution was demonstrated on denaturing polyacrylamide gel media. The high-throughput multiplex capabilities of this genetic analysis platform were demonstrated by the simultaneous separation of STR amplicons representing 122 samples in ninety-six 5.5-cm-long channels in <8 min. Sizing values obtained for these amplicons on the CAE microchannel plate were comparable to those measured on a conventional commercial CAE instrument and exhibit <1% sizing variance. CONCLUSIONS Energy-transfer-cassette labeling and microfabricated CAE microchannel plates allow high-performance multiplex STR analyses.
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Affiliation(s)
- I L Medintz
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
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Berti L, Medintz IL, Tom J, Mathies RA. Energy-transfer cassette labeling for capillary array electrophoresis short tandem repeat DNA fragment sizing. Bioconjug Chem 2001; 12:493-500. [PMID: 11459452 DOI: 10.1021/bc000155w] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Energy-transfer (ET) dye-labeled primers significantly improve fluorescent DNA detection because they permit excitation at a single common wavelength and they produce well separated and intense acceptor dye emission. Recently, a new ET cassette technology was developed [Berti, L. et al. (2001) Anal. Biochem. 292, 188-197] that can be used to label any PCR, sequencing, or other primer of interest. In this report we examine the utility of this ET cassette technology by labeling seven different short tandem repeat (STR) specific primers with each of the four ET cassettes and analyzing the PCR products generated on a MegaBACE-1000 capillary array electrophoresis system. More than 60 amplicons were generated and successfully analyzed with the ET cassette-labeled primers. Both forward and reverse primers were labeled for multiplex PCR amplification and analysis. Single base pair resolution was achieved with all four ET cassettes. This ET cassette-primer labeling procedure is ideally suited for creating four-color fluorescent ET primers for STR and other DNA assays where large numbers of different loci are analyzed including sequencing, genetic identification, gene mapping, loss of heterozygosity testing, and linkage analysis.
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Affiliation(s)
- L Berti
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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Medintz I, Wong WW, Berti L, Shiow L, Tom J, Scherer J, Sensabaugh G, Mathies RA. High-performance multiplex SNP analysis of three hemochromatosis-related mutations with capillary array electrophoresis microplates. Genome Res 2001; 11:413-21. [PMID: 11230165 PMCID: PMC311034 DOI: 10.1101/gr.164701] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2000] [Accepted: 01/02/2001] [Indexed: 01/02/2023]
Abstract
An assay is described for high-throughput single nucleotide polymorphism (SNP) genotyping on a microfabricated capillary array electrophoresis (CAE) microchip. The assay targets the three common variants at the HFE locus associated with the genetic disease hereditary hemochromatosis (HHC). The assay employs allele-specific PCR (ASPCR) for the C282Y (845g->a), H63D (187c->g), and S65C (193a->t) variants using fluorescently-labeled energy-transfer (ET) allele-specific primers. Using a 96-channel radial CAE microplate, the labeled ASPCR products generated from 96 samples in a reference Caucasian population are simultaneously separated with single-base-pair resolution and genotyped in under 10 min. Detection is accomplished with a laser-excited rotary four-color fluorescence scanner. The allele-specific amplicons are differentiated on the basis of both their size and the color of the label emission. This study is the first demonstration of the combined use of ASPCR with ET primers and microfabricated radial CAE microplates to perform multiplex SNP analyses in a clinically relevant population.
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Affiliation(s)
- I Medintz
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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Abstract
BACKGROUND Controversy regarding the timing for the repair of tetralogy of Fallot centers around initial palliation versus primary repair for the symptomatic neonate/young infant and the optimal age for repair of the asymptomatic child. We changed our approach from one of initial palliation in the infant to one of primary repair around the age of 6 months, or earlier if clinically indicated. We examined the effects of this change in protocol and age on outcomes. METHODS AND RESULTS The records of 227 consecutive children who had repair of isolated tetralogy of Fallot from January 1993 to June 1998 were reviewed. The median age of repair by year fell from 17 to 8 months (P:<0.01). The presence of a palliative shunt at the time of repair decreased from 38% to 0% (P:<0.01). Mortality (6 deaths, 2. 6%) improved with time (P:=0.02), with no mortality since the change in protocol (late 1995/early 1996). Multivariate analysis for physiological outcomes of time to lactate clearance, ventilation hours, and length of stay, but not death, demonstrated that an age <3 months was independently associated with prolongation of times (P:<0.03). Each of the deaths occurred with primary repair at an age >12 months. The best survival and physiological outcomes were achieved with primary repair in children aged 3 to 11 months. CONCLUSIONS On the basis of mortality and physiological outcomes, the optimal age for elective repair of tetralogy of Fallot is 3 to 11 months of age.
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Affiliation(s)
- G S Van Arsdell
- Division of Cardiac Surgery and Cardiology, The Hospital for Sick Children, Toronto, University of Toronto, Toronto, Canada.
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Nusrat A, Chen JA, Foley CS, Liang TW, Tom J, Cromwell M, Quan C, Mrsny RJ. The coiled-coil domain of occludin can act to organize structural and functional elements of the epithelial tight junction. J Biol Chem 2000; 275:29816-22. [PMID: 10887180 DOI: 10.1074/jbc.m002450200] [Citation(s) in RCA: 159] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Occludin is an integral membrane protein that has been suggested to play a role in the organization and dynamic function of the epithelial tight junction (TJ). A number of other proteins have also been described to localize to the TJ. We have used a novel bait peptide method to investigate potential protein-protein interactions of the putative coiled-coil domain of occludin with some of these other TJ proteins. A 27-amino acid peptide of the human occludin sequence was synthesized, biotinylated at the N terminus, and modified to contain a photoactive moiety at either its hydrophobic or hydrophilic surface. These bait peptides were alpha-helical in solution, characteristic of coiled-coil structures. Photoactivation studies in the presence and absence of control peptides were used to assess the potential interactions in polarized sheets of a human intestinal cell line T84. Although a large number of proteins associated with the TJ or that are known to be involved in regulatory events of epithelial cells failed to be specifically labeled, occludin itself, ZO-1, protein kinase C-zeta, c-Yes, the regulatory subunit of phosphatidylinositol 3-kinase, and the gap junction component connexin 26 were specifically labeled. Our data demonstrate the potential of one specific domain of occludin, contained within 27 amino acids, to coordinate the binding of proteins that have been previously suggested to modulate TJ structure and function.
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Affiliation(s)
- A Nusrat
- Epithelial Pathobiology Research Unit, Department of Pathology and Laboratory Medicine, Emory University, Atlanta, Georgia 30322, USA
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Suggett S, Kirchhofer D, Hass P, Lipari T, Moran P, Nagel M, Judice K, Schroeder K, Tom J, Lowman H, Adams C, Eaton D, Devaux B. Use of phage display for the generation of human antibodies that neutralize factor IXa function. Blood Coagul Fibrinolysis 2000; 11:27-42. [PMID: 10691097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
The use of libraries of phage-displayed human single-chain antibody fragments (scFv) has become a new, powerful tool in rapidly obtaining therapeutically useful antibodies. Here, we describe the generation of human scFv and F(ab')2 directed against the gamma-carboxyglutamic acid (Gla) domain of coagulation factor IX. A large library of human scFv, displayed either on M13 phage or expressed as soluble proteins, was screened for binding to human Gla-domain peptide (Tyr1-Lys43). Among a panel of scFv that bound to the factor IX-Gla domain, six scFv clones recognized full-length factor IX and exhibited strong inhibitory activity of factor IX in vitro. After reformatting as F(ab')2, the affinity for factor IX of three selected clones was determined: 10C12 Kd = 1.6 nmol/l, 13D1 Kd = 2.9 nmol/l, and 13H6 Kd = 0.46 nmol/l. The antibodies specifically bound to factor IX and not to other coagulation factors, as assessed by enzyme-linked immunosorbent-type and human plasma clotting assays. The complementarity determining region amino acid sequences of clones 10C12 and 13D1 only differed at a single residue, whereas 13H6 showed little homology, suggesting that 13H6 binds to a different epitope within the factor IX-Gla domain. Despite the slightly lower affinity of 10C12 F(ab')2 versus 13H6 F(ab')2, 10C12 was consistently more potent than 13H6 in prolonging the activated partial thromboplastin time (APTT), in inhibiting platelet-mediated plasma clotting, and in inhibiting factor X activation by the intrinsic Xase complex. Finally, 10C12 F(ab')2 also recognized and neutralized factor IX/factor IXa of different species, as demonstrated by the specific APTT prolongation of dog, mouse, baboon and rabbit plasma. In summary, the results validate the usefulness of scFv phage-displayed libraries to rapidly generate fully human antibodies as potential new therapeutics for thrombotic disorders.
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Affiliation(s)
- S Suggett
- Department of Antibody Technologies, Genentech, Inc., South San Francisco, CA 94080, USA
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Tom J, Tom L. Tibiofibular diastasis in the injured ankle. Am Fam Physician 1998; 58:864, 866. [PMID: 9767723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
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Abstract
The purpose of this study was to test the hypothesis that specific cytokines are involved in the initiation and evolution of the fibrotic process in adhesive capsulitis of the shoulder. After approval from the Institutional Review Board, biopsies of shoulder capsule and synovium were collected during shoulder arthroscopy from 19 patients with adhesive capsulitis, 14 patients with nonspecific synovitis and no fibrosis or clinical evidence of adhesive capsulitis, and seven patients undergoing surgery for another pathology who had a normal capsule and synovium. Immunohistochemical localization with monoclonal antibodies to transforming growth factor-beta and its receptor, platelet-derived growth factor and its receptor, basic fibroblast growth factor, interleukin-1 beta, tumor necrosis factor-alpha, and hepatocyte growth factor was performed using standard immunoperoxidase techniques. The frequency of cytokine staining was correlated with the clinical diagnosis. Synovial cells, fibroblasts, T-cells, and B-cells were identified with specific antibodies, and newly synthesized matrix was examined for type-I and type-III collagen by immunohistochemical staining. The predominant cell types present were synovial cells and fibroblasts. Staining for type-III collagen in adhesive capsulitis tissues indicated new deposition of collagen in the capsule. There was staining for transforming growth factor-beta and its receptor, platelet-derived growth factor and its receptor, interleukin-1 beta, and tumor necrosis factor-alpha in adhesive capsulitis and nonspecific synovitis tissues, compared with minimal staining in normal capsule. Staining was more frequent in synovial cells than in capsular cells. The frequency of cell and matrix staining for transforming growth factor-beta, platelet-derived growth factor, and hepatocyte growth factor was greater in adhesive capsulitis tissues than in those from patients with nonspecific synovitis. No difference in the frequency of staining between primary (idiopathic) and secondary adhesive capsulitis was found. The results of this study indicate that adhesive capsulitis involves both synovial hyperplasia and capsular fibrosis. Cytokines such as transforming growth factor-beta and platelet-derived growth factor may be involved in the inflammatory and fibrotic processes in adhesive capsulitis. Matrix-bound transforming growth factor-beta may act as a persistent stimulus, resulting in capsular fibrosis. Understanding the basic pathophysiology of adhesive capsulitis is an important step in the development of clinically useful antifibrotic agents that may serve as novel treatments for patients with this conditions.
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Affiliation(s)
- S A Rodeo
- Laboratory for Soft Tissue Research, Hospital for Special Surgery, New York, NY 10021, USA.
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Abstract
The serine protease, subtilisin BPN', was engineered to cleave proteins after tribasic sequences in a manner that resembles the substrate specificity of furin, one of the mammalian subtilisin homologs that processes prohormones. As a starting point we used a double mutant of subtilisin BPN' (N62D/ G166D) that showed substantial preference for cleaving after sequences having consecutive dibasic residues (namely, at the P1 and P2 substrate positions) [Ballinger et al. (1995) Biochemistry 34, 13312-13319]. Additional specificity for basic residues was engineered at the P4 position by introducing subtilisin-to-furin substitutions at three hydrophobic residues that composed the S4 subsite (Y104, I107, and L126). Initial attempts to incorporate a Y104D or I107E mutation or the Y104D/I107E double mutation into the dibasic specific enzyme failed to generate the processed enzyme. The problem was traced to the inability of the mutant prosubtilisins to process themselves and fold correctly. Replacing the natural processing site sequence (AHAY) with a good furin substrate sequence (RHKR) resulted in expression of the triple subtilisin mutant (N62D/Y104D/G166D) we call "furilisin". Furilisin hydrolyzes synthetic tribasic substrates (succinyl-RAKR-pNA or succinyl-KAKR-pNA) with high catalytic efficiency (kcat/K(m) > 3 x 10(5) M-1 s-1) and discriminates in favor of Arg versus Ala at the P4 position by a factor of 360. The overall specificity change versus the wild-type enzyme was dramatic. For example, succinyl-RAKR-pNA was cleaved approximately 60000 times faster than succinyl-AAPF-pNA, a good substrate for wild-type subtilisin. Similarly, furilisin was inhibited (K1* = 29 nM) by a variant of the turkey ovomucoid third domain inhibitor that contained an engineered furin substrate site (RCKR decreases) [Lu et al. (1993) J. Biol. Chem. 268, 14583-14585] and not by one having a good wild-type subtilisin substrate sequence (ACTL decreases). Interestingly, the extreme changes in substrate specificity resulted from substantial synergy between the engineered subsites. These studies provide a basic example of how to manipulate substrate specificity in a modular fashion, thereby creating an engineered-enzyme that may be useful as a protein processing tool.
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Affiliation(s)
- M D Ballinger
- Department of Protein Engineering, Genentech, Inc., South San Francisco, California 94080, USA
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Jin H, Li B, Cunningham B, Tom J, Yang R, Sehl P, Thomas GR, Ko A, Oare D, Lowe DG. Novel analog of atrial natriuretic peptide selective for receptor-A produces increased diuresis and natriuresis in rats. J Clin Invest 1996; 98:969-76. [PMID: 8770869 PMCID: PMC507512 DOI: 10.1172/jci118881] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Atrial natriuretic peptide (ANP) binds to natriuretic peptide receptor-A (NPR-A), a membrane guanylyl cyclase, and to natriuretic peptide receptor-C (NPR-C), which plays a role in peptide clearance. Rat ANP (rANP) mutants that bind rat NPR-A selectively over rat NPR-C were isolated from randomized libraries of rANP-display phage by differential panning. One variant was identified with reduced NPR-C binding; rANP (G16R, A17E, Q18A) [rANP(REA18)]. Synthetic rANP(REA18) was equipotent with rANP in stimulating cGMP production from cloned rat NPR-A (ED50 = 1.8 nM) and was reduced in NPR-C binding by approximately 200-fold. When infused into conscious rats at 0.325 microg/min for 30 min rANP elicited an identical decrease in blood pressure compared with 0.25 microg/min of rANP(REA18), however the natriuretic (P < 0.05) and diuretic (P = 0.07) responses to rANP(REA18) were greater. These data are consistent with a role for NPR-C as a local decoy receptor attenuating NPR-A effects in the kidney, where these receptors are coexpressed. Improved NPR-A specificity could provide more effective natriuretic peptides for treatment of acute renal failure or heart failure.
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Affiliation(s)
- H Jin
- Department of Cardiovascular Research, Genentech, Inc., South San Francisco, California 94080, USA
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Abstract
The bacterial serine protease, subtilisin BPN', has been mutated so that it will efficiently and selectively cleave substrates containing two consecutive basic (dibasic) residues. Mutants were designed on the basis of both the structure of subtilisin BPN' and considerations of sequence differences between it and eukaryotic homologs, Kex2, PC2, and furin, which are known to cleave dibasic substrates. These eukaryotic proteases have high sequence homology to one another but differ substantially from subtilisin BPN' in loops that interact with the substrate. When these loops were grafted into subtilisin BPN', the mutated enzyme could not be expressed, presumably due to destabilization of the folded enzyme. We noted that several neutral residues in subtilisin BPN' (Gly 166, Ser 33, and Asn 62) that are positioned to interact with a dibasic substrate are acidic residues at analogous positions in Kex2. Mutating these residues individually to either Glu or Asp in subtilisin BPN' resulted in systematic shifts in substrate specificity (kcat/Km) toward basic residues and away from the natural preference for hydrophobic substrates. A combination mutant, where Asn 62 was changed to Asp and Gly 166 was changed to Asp (N62D/G166D), had a larger than additive shift in specificity toward dibasic substrates. This unexpectedly large change was confirmed by detailed analysis with a variety of synthetic substrates. Additional substrate determinants were revealed by sorting a library of phage particles (substrate phage) containing five contiguous randomized residues. This method identified a particularly good substrate (Asn-Leu-Met-Arg-Lys) that was selectively cleaved in the context of a fusion protein by the N62D/G166D subtilisin.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M D Ballinger
- Department of Protein Engineering, Genentech, Inc., South San Francisco, California 94080, USA
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Tom L, Thomassen E, Tom J. Late recognition of a rectal tear associated with a pelvic fracture. A case report. J Bone Joint Surg Am 1995; 77:1291. [PMID: 7642677 DOI: 10.2106/00004623-199508000-00023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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Jackson DY, Burnier J, Quan C, Stanley M, Tom J, Wells JA. A designed peptide ligase for total synthesis of ribonuclease A with unnatural catalytic residues. Science 1994; 266:243-7. [PMID: 7939659 DOI: 10.1126/science.7939659] [Citation(s) in RCA: 221] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
An engineered variant of subtilisin BPN', termed subtiligase, which efficiently ligates esterified peptides in aqueous solution, was used for the complete synthesis of ribonuclease (RNase) A that contains unnatural catalytic residues. Fully active RNase A (124 residues long) was produced in milligram quantities by stepwise ligation of six esterified peptide fragments (each 12 to 30 residues long) at yields averaging 70 percent per ligation. Variants of RNase A were produced in which the catalytic histidines at positions 12 and 119 were substituted with the unnatural amino acid 4-fluorohistidine, which has a pKa of 3.5 compared to 6.8 for histidine. Large changes in the profile of the pH as it affects rate occurred for the single and double mutants with surprisingly little change in the kcat for either the RNA cleavage or hydrolysis steps. The data indicate that these imidazoles function as general acids and bases, but that the proton transfer steps are not rate-limiting when the imidazoles are present in their correct protonation states. These studies indicate the potential of subtiligase for the blockwise synthesis of large proteins.
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Affiliation(s)
- D Y Jackson
- Department of Protein Engineering, Genentech, Inc., South San Francisco, CA 94080
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Mordan LJ, Burnett TS, Zhang LX, Tom J, Cooney RV. Inhibitors of endogenous nitrogen oxide formation block the promotion of neoplastic transformation in C3H 10T1/2 fibroblasts. Carcinogenesis 1993; 14:1555-9. [PMID: 7689037 DOI: 10.1093/carcin/14.8.1555] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The endogenous production of nitric oxide (NO) and its role in the neoplastic transformation of C3H 10T1/2 mouse fibroblasts were investigated. NO production, as indicated by NO2- in the culture medium, was increased in cells initiated with 3-methylcholanthrene or stimulated with the combination of interferon-gamma (IFN gamma, 10 ng/ml) plus bacterial lipopolysaccharide (LPS, 1 micrograms/ml). NO2- was detectable within 24-48 h of IFN gamma/LPS treatment and accumulated to micromolar concentrations within 4 days. NO production was inhibited in a dose-dependent manner by analogs of L-arginine in which the terminal guanidino nitrogen is blocked, consistent with NO production by the oxidative deamination of L-arginine by nitric oxide synthase (NOS). IFN gamma/LPS-stimulated cells expressed a 4.4 kb mRNA which hybridized to a probe for the mouse macrophage-inducible NOS. Expression of the rat cerebellar constitutive NOS was not detected in these cells. Arginine analogs added to the culture medium during the post-confluence promotional stages of the C3H 10T1/2 transformation assay blocked the formation of transformed foci in a dose-dependent manner comparable to their inhibition of NO production. These data demonstrate that C3H 10T1/2 mouse fibroblasts are a useful model for the study of the effects of endogenous NO production in carcinogenesis and suggest that NO plays a significant role in the promotional phase of neoplastic transformation of these cells.
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Affiliation(s)
- L J Mordan
- Molecular Oncology Program, University of Hawaii, Manoa, Honolulu 96813
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Abstract
Maize (Zea mays L.) cytosolic 6-phosphogluconate dehydrogenase isozymes (EC 1.1.1.44; 6-PGD) are encoded by unlinked loci Pgd1 and Pgd2. Two families from a Robertson's Mutator line were isolated which have no detectable expression of Pgd2. These Pgd2-null mutants and a Pgd1-null line were used to generate plants homozygous for null alleles at both cytosolic 6-PGD loci. The specific activity of 6-PGD in the double-null mutant was between 20 and 30% of wild-type levels in root extracts. The double-null mutant was reproductively viable in a moderate environment, suggesting that wild-type levels of cytosolic 6-PGD activity are not essential for growth. Isozyme dimer ratios in roots, leaves, and scutellum were binomial and reflected the wild-type gene copy number. 6-PGD isozymes showed tissue- and cell type-specific expression.
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Affiliation(s)
- J Bailey-Serres
- Department of Botany and Plant Sciences, University of California, Riverside 92521
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21
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Abstract
To assess the efficacy of operative and nonoperative therapy of small bowel obstruction (SBO) in patients with a previous diagnosis of cancer, a review of 54 cases was carried out. The 32 men and 22 women had a mean age of 58 years. At presentation with SBO, 26 patients (48%) had known recurrent cancer. Forty patients were initially treated nonoperatively; 11 (28%) had resolution of their SBO after a mean of 7 days of nasogastric suction. Five of 11 patients developed recurrent SBO prior to death. Thirty-seven patients underwent laparotomy, 14 on the day of admission and 23 after failure of nasogastric suction. Twenty-five of 37 (68%) had obstruction due to recurrent carcinoma. Small bowel obstruction due to recurrent cancer occurred earlier (21 +/- 5 months) than SBO from benign causes (61 +/- 18 months; p < 0.01). Mean survival for patients with malignant obstruction (5 +/- 1 month) was significantly shorter than for those with benign obstruction (50 +/- 10 months; p < 0.001). The 30-day and in-hospital mortality rates for the 25 surgically treated patients with malignant SBO were 24% and 28%, respectively; in 9 of 25 (36%), the obstruction failed to fully resolve. The only factor predictive of in-hospital mortality was obstruction secondary to cancer (p < 0.05). The median posthospital survival for surgically treated patients with malignant SBO was only 2.5 months. We conclude that: (1) patients should be given an initial trial of nonoperative therapy; (2) patients with no known recurrence or a long interval to the development of SBO should be aggressively treated with early surgery if nonoperative treatment fails; and (3) for patients with known abdominal recurrence in whom nonoperative therapy fails, the results of surgical palliation are grim. Innovative approaches are needed to maximize palliation while also limiting morbidity and mortality.
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Affiliation(s)
- J A Butler
- Department of Surgery, Harbor-UCLA Medical Center, Torrance 90502
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22
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Abrahmsén L, Tom J, Burnier J, Butcher KA, Kossiakoff A, Wells JA. Engineering subtilisin and its substrates for efficient ligation of peptide bonds in aqueous solution. Biochemistry 1991; 30:4151-9. [PMID: 2021606 DOI: 10.1021/bi00231a007] [Citation(s) in RCA: 171] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Protein engineering techniques were used to construct a derivative of the serine protease subtilisin that ligates peptides efficiently in water. The subtilisin double mutant in which the catalytic Ser221 was converted to Cys (S221C) and Pro225 converted to Ala (P225A) has 10-fold higher peptide ligase activity and at least 100-fold lower amidase activity than the singly mutated thiolsubtilisin (S221C) that was previously shown to have some peptide ligase activity [Nakatsuka, T., Sasaki, T., & Kaiser, E.T. (1987) J. Am. Chem. Soc. 109, 3808-3810]. A 1.5-A X-ray crystal structure of an oxidized derivative of the double mutant (S221C/P225A) supports the protein design strategy in showing that the P225A mutation partly relieves the steric crowding expected from the S221C substitution, thus accounting for its improved catalytic efficiency. Stable and synthetically reasonable alkyl ester peptide substrates were prepared that rapidly acylate the S221C/P225A enzyme, and aminolysis of the resulting thioacyl-enzyme intermediate by various peptides is strongly preferred over hydrolysis. The efficiency of aminolysis is relatively insensitive to the sequence of the first two residues in the acyl acceptor peptide whose alpha-amino group attacks the thioacyl-enzyme. To obtain greater flexibility in the choice of coupling sites, a set of three additional peptide ligases were engineered by introducing mutations into the parent ligase (S221C/P225A) that were previously shown to change the specificity of subtilisin for the residue nearest the acyl bond (the P1 residue). The specificity properties of the parent ligase and derivatives of it paralleled those of wild type and corresponding specificity variants.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- L Abrahmsén
- Department of Protein Engineering, Genentech, Inc., South San Francisco, California 94080
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23
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Kenley RA, Hamme KJ, Lee MO, Tom J. Silica-based size exclusion chromatography to characterize the decapeptide nafarelin in a controlled-release pharmaceutical formulation. Anal Chem 1987; 59:2050-4. [PMID: 2960251 DOI: 10.1021/ac00144a009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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24
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Bradshaw SD, Cohen D, Katsaros A, Tom J, Owen FJ. Determination of 18O by prompt nuclear reaction analysis: application for measurement of microsamples. J Appl Physiol (1985) 1987; 63:1296-302. [PMID: 3115954 DOI: 10.1152/jappl.1987.63.3.1296] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
A method is described for the routine determination of 18O concentrations in microsamples of biological fluids. The method utilizes the prompt nuclear reaction 18O(p, alpha o)15N, and 846-keV protons from a 3-MeV Van de Graaff Accelerator are focused on approximately 2,000-A-thick Ta2O5 targets prepared by anodic oxidation from 50-microliter samples of water distilled from blood or other biological fluids. The broad cross section of the resonance peak for this nuclear reaction (47 keV) ensures high yields, especially at small reaction angles, and the high-energy alpha particles produced by the reaction (4 MeV) are readily separated from scattered protons by the use of an aluminized Mylar foil of suitable thickness. Background levels of 18O (0.204 atom%) can be detected with run times of approximately 5-8 min, and the sensitivity of the method is of the order of 0.05 atom %. Experimental error due to sample preparation was found to be 1.7%, and counting errors were close to theoretical limits so that total error was of the order of 2.5%. Duplicate samples were analyzed by use of the 18O(p, alpha o)15N reaction at Lucas Heights, Australia, and the 18O(p,n)18F reaction by the method of Wood et al. (Anal. Chem. 47: 646-650, 1975) at the University of California, Los Angeles, and the agreement was excellent (y = 1.0123x - 0.0123, r = 0.991, P less than 0.001). The theoretical limitations and the general applicability of the method in biological studies designed to estimate the rate of metabolism of free-ranging animals are discussed.
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Affiliation(s)
- S D Bradshaw
- Zoology Department, University of Western Australia, Perth
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25
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Andrews WH, Poelma PL, Wilson CR, Abeyta C, Chu GS, Cruz L, Dorrett L, English L, Estela LA, Guarino P, Hayden MA, Haymond RE, Heagy J, Hoffman CD, Kallander K, Krout DJ, Landry WL, Latt T, Ludwig SG, Martinez EE, McDonald RL, McKee CR, Melanson DE, Otto LA, Palmieri MJ, Roderick CN, Sado PN, Sawai E, Stout DK, Tardio JL, Tom J, Twohy CW, Wagner D, White WD, Wong P. Comparative Efficiency of Brilliant Green, Bismuth Sulfite, Salmonella-Shigella, Hektoen Enteric, and Xylose Lysine Desoxycholate Agars for the Recovery of Salmonella from Foods: Collaborative Study. J AOAC Int 1981. [DOI: 10.1093/jaoac/64.4.899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
The relative efficiency of brilliant green (BG), bismuth sulfite (BS), Salmonella-Shigella (SS), xylose lysine desoxycholate (XLD), and Hektoen enteric (HE) agars for the recovery of Salmonella from 5 foods was collaboratively studied in 11 laboratories. The analytical efficiency of various paired combinations of the 5 agars was statistically compared according to 3 parameters: (1) productivity or recovery of Salmonella, (2) rate of enumeration of cultures that were false positive for Salmonella, and (3) rate of enumeration of false-negative reactions. In descending order of productivity, the sequential rankingwasBS, XLD, HE, BG, and SS agars. In ascending order, the rates of false-positive reactions based on a statistical analysis of paired agar combinations was HE, BS, BG and XLD (tie), and SS agars. Analogously, in ascending order, the sequence of false-negative reaction rates was BS, XLD, HE, BG, and SS agars. The combination of BS, XLD, and HE agars is more efficient for recovery of Salmonella from foods than is the present official combination of BG, BS, and SS agars. The revision of official final action method 46.054 to replace the combination of BG, BS, and SS agars with a combination of BS, XLD, and HE agars has been adopted official first action.
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Affiliation(s)
- Wallace H Andrews
- Food and Drug Administration, Division of Microbiology, Washington, DC 20204
| | - Paul L Poelma
- Food and Drug Administration, Division of Microbiology, Washington, DC 20204
| | - Clyde R Wilson
- Food and Drug Administration, Division of Microbiology, Washington, DC 20204
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Hannam AG, Siu W, Tom J. A comparison of monopolar and bipolar pulp-testing. Dent J 1974; 40:124-8. [PMID: 4521439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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