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Card E, Bellini SG, Williams DP, Patten EV. Current Dietetic Internship Admission Criteria and Selection Processes: Results From an Electronic Survey of Directors. J Acad Nutr Diet 2023; 123:643-654.e6. [PMID: 35998866 DOI: 10.1016/j.jand.2022.08.126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 07/26/2022] [Accepted: 08/18/2022] [Indexed: 10/15/2022]
Abstract
BACKGROUND Members of the dietetics profession have been discussing and confronting the lack of diversity within the profession. The Academy of Nutrition and Dietetics is committed to diversity and inclusion efforts. OBJECTIVE Our aim was to determine current admission criteria and practices used by Dietetic Internships (DIs) across the United States. DESIGN This was a cross-sectional study using electronic survey with open and close-ended items conducted in the fall of 2020. PARTICIPANTS The electronic survey was distributed to 261 DI directors. Statistical analysis performed Descriptive statistics were calculated for each variable using SPSS software. Six topically related open-ended items were analyzed through a qualitative thematic approach. RESULTS DI directors (n = 89) were primarily female (n = 76) and White (n = 77). Most admissions process and criteria decisions were made by committees. Directors (n = 79) reported using a predefined rubric/scoring system for candidate evaluation. Many (n = 60) indicated not using Graduate Record Examination scores. All reported considering Didactic Program in Dietetics' grade point average; personal statement quality; professional interests and goals; and type and quantity of previous dietetics-related work and volunteer experience. The admission factors rated (on a 7-point scale) most important were quality of interview (mean = 6.03), Didactic Program in Dietetics' grade point average (mean = 5.67), type of work and volunteer experience (mean = 5.62), quality of personal statement (mean = 5.5), recommender comments (mean = 5.41), and quantity of work and volunteer experience (mean = 5.40). Most (n = 80) indicated that they were satisfied with their selection processes. CONCLUSIONS Educators should continue refining admissions processes as professional gatekeepers, consider reducing application fees, diversifying and training selection committees, re-evaluating admission criteria, and assessing how criteria weights.
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Richards R, Brown LB, Williams DP, Eggett DL. Developing a Questionnaire to Evaluate College Students' Knowledge, Attitude, Behavior, Self-efficacy, and Environmental Factors Related to Canned Foods. J Nutr Educ Behav 2017; 49:117-124.e1. [PMID: 27876324 DOI: 10.1016/j.jneb.2016.10.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 09/19/2016] [Accepted: 10/02/2016] [Indexed: 06/06/2023]
Abstract
OBJECTIVE Develop a questionnaire to measure students' knowledge, attitude, behavior, self-efficacy, and environmental factors related to the use of canned foods. METHODS The Knowledge-Attitude-Behavior Model, Social Cognitive Theory, and Canned Foods Alliance survey were used as frameworks for questionnaire development. Cognitive interviews were conducted with college students (n = 8). Nutrition and survey experts assessed content validity. Reliability was measured via Cronbach α and 2 rounds (1, n = 81; 2, n = 65) of test-retest statistics. Means and frequencies were used. RESULTS The 65-item questionnaire had a test-retest reliability of .69. Cronbach α scores were .87 for knowledge (9 items), .86 for attitude (30 items), .80 for self-efficacy (12 items), .68 for canned foods use (8 items), and .30 for environment (6 items). CONCLUSIONS AND IMPLICATIONS A reliable questionnaire was developed to measure perceptions and use of canned foods. Nutrition educators may find this questionnaire useful to evaluate pretest-posttest changes from canned foods-based interventions among college students.
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Affiliation(s)
- Rickelle Richards
- Department of Nutrition, Dietetics, and Food Science, Brigham Young University, Provo, UT.
| | - Lora Beth Brown
- Department of Nutrition, Dietetics, and Food Science, Brigham Young University, Provo, UT
| | - D Pauline Williams
- Department of Nutrition, Dietetics, and Food Science, Brigham Young University, Provo, UT
| | - Dennis L Eggett
- Department of Statistics, Brigham Young University, Provo, UT
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Williams DP, Joseph N, Sones E, Chetluru S, Hillecke TK, Thayer JF, Koenig J. Effects of Body Mass Index on Parasympathetic Nervous System Reactivity and Recovery Following Orthostatic Stress. J Nutr Health Aging 2017; 21:1250-1253. [PMID: 29188886 DOI: 10.1007/s12603-016-0817-8] [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] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Vagally mediated heart rate variability (vmHRV), defined as the beat-to-beat fluctuations in a heart series mediated by the vagus nerve, serves as a non-invasive index of parasympathetic nervous system (PNS) activity. Lower resting state vmHRV is associated with greater body mass index (BMI), providing a psychophysiological pathway linking obesity with health and disease. However little research has been conducted to examine how BMI may influence PNS reactivity to orthostatic stress. The present study sought to explore this in a sample of 59 individuals (44 females, mean age = 24.37 years, age range 19-65 years). VmHRV was measured throughout the 5-minute baseline (sitting), orthostatic (standing), and recovery (sitting) conditions. Individuals were stratified into low (BMI < 20), moderate (BMI 20-25), and high (BMI > 25) BMI groups. Results indicate that the high BMI group had a greater decrease in vmHRV from baseline to standing in comparison to the moderate BMI group. Furthermore, the low BMI group showed lower vmHRV during recovery compared to baseline, suggesting that these individuals did not fully recover from the standing position. Taken together, these results extend previous literature showing that those with low and high BMI can show different yet maladaptive patterns of vmHRV in response to orthostatic stress.
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Affiliation(s)
- D P Williams
- D. Williams , Department of Psychology, The Ohio State University, 1835 Neil Avenue, Columbus, OH, 43210, USA: Tel: + 1 614 688 5793. E-mail address:
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Williams DP, O'Brien S, Doran E, Price AJ, Beard DJ, Murray DW, Beverland DE. Early postoperative predictors of satisfaction following total knee arthroplasty. Knee 2013; 20:442-6. [PMID: 23777807 DOI: 10.1016/j.knee.2013.05.011] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Revised: 04/26/2013] [Accepted: 05/22/2013] [Indexed: 02/02/2023]
Abstract
BACKGROUND Despite the excellent total knee arthroplasty (TKA) results reported using traditional outcome measures, dissatisfaction rates of up to 30% are reported following surgery. Although several preoperative factors have been identified as possible predictors of satisfaction, there is conflicting evidence. Identification of dissatisfaction in the early postoperative assessment may therefore be an alternative consideration. METHODS We examined the relationship between 12-month satisfaction, and early post-operative outcomes in a cohort of 486 TKA patients. Preoperative, and postoperative outcome measures at 3- and 12-months (Oxford knee score, pain score, SF12, and knee motion), were analysed and compared between patients who were satisfied and dissatisfied at 12-months following TKA. Mean scores, and postoperative change in scores were calculated. Postoperative outcomes were examined for correlation with satisfaction, and multivariate logistic regression models used to identify potential predictors of dissatisfaction. RESULTS Overall satisfaction was 77.0%. No preoperative differences were observed between groups. Dissatisfaction was associated with worse postoperative status across all outcome measures (p<0.001), except the 3-month SF12-physical component (p=0.052). Dissatisfied patients demonstrated minimal further improvement or even worsening of outcome scores between 3- and 12-months postoperatively (p<0.02). Both the 3-month OKS (OR=1.15, p<0.001), and knee flexion (OR=1.03, p=0.009) were significant predictors of subsequent 12-month satisfaction. CONCLUSIONS Dissatisfaction following TKA is associated with worse outcomes as early as 3months following surgery, with minimal further improvement subsequently achieved at 12-months. Early postoperative assessment following TKA should therefore be considered, including clinical assessment, to identify those patients at risk of dissatisfaction.
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Affiliation(s)
- D P Williams
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, United Kingdom.
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Abstract
The aim of this study was to review the early outcome of the Femoro-Patella Vialla (FPV) joint replacement. A total of 48 consecutive FPVs were implanted between December 2007 and June 2011. Case-note analysis was performed to evaluate the indications, operative histology, operative findings, post-operative complications and reasons for revision. The mean age of the patients was 63.3 years (48.2 to 81.0) and the mean follow-up was 25.0 months (6.1 to 48.9). Revision was performed in seven (14.6%) at a mean of 21.7 months, and there was one re-revision. Persistent pain was observed in three further patients who remain unrevised. The reasons for revision were pain due to progressive tibiofemoral disease in five, inflammatory arthritis in one, and patellar fracture following trauma in one. No failures were related to the implant or the technique. Trochlear dysplasia was associated with a significantly lower rate of revision (5.9% vs 35.7%, p = 0.017) and a lower incidence of revision or persistent pain (11.8% vs 42.9%, p = 0.045). Focal patellofemoral osteoarthritis secondary to trochlear dysplasia should be considered the best indication for patellofemoral replacement. Standardised radiological imaging, with MRI to exclude overt tibiofemoral disease should be part of the pre-operative assessment, especially for the non-dysplastic knee.
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Affiliation(s)
- D P Williams
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Botnar Research Centre, University of Oxford, Windmill Road, Oxford OX3 7LD, UK.
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Williams DP, Price AJ, Beard DJ, Hadfield SG, Arden NK, Murray DW, Field RE. The effects of age on patient-reported outcome measures in total knee replacements. Bone Joint J 2013; 95-B:38-44. [PMID: 23307671 DOI: 10.1302/0301-620x.95b1.28061] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We present a comparison of patient-reported outcomes (PROMs) in relation to patient age, in patients who had received a total (TKR) or unicompartmental knee replacement (UKR). The outcome was evaluated using the Oxford knee score (OKS), EuroQol (EQ-5D) and satisfaction scores. Patients aged 65 to 84 years demonstrated better pre-operative function scores than those aged < 65 years (OKS, p = 0.03; EQ-5D, p = 0.048) and those aged ≥ 85 years (OKS, p = 0.03). Post-operative scores were comparable across age groups, but a linear trend for greater post-operative improvement in OKS and EQ-5D was seen with decreasing age (p < 0.033). The overall mean satisfaction score at six months was 84.9, but those aged < 55 years exhibited a lower mean level of satisfaction (78.3) compared with all other age groups (all p < 0.031). The cumulative overall two-year revision rate was 1.3%. This study demonstrates that good early outcomes, as measured by the OKS and EQ-5D, can be anticipated following knee replacement regardless of the patient's age, although younger patients gain greater improvement. However, the lower satisfaction in those aged < 55 years is a concern, and suggests that outcome is not fully encapsulated by the OKS and EQ-5D evaluation, and raises the question whether the OKS alone is an appropriate measure of pain and function in younger, more active individuals.
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Affiliation(s)
- D P Williams
- University of Oxford, Nuffield Department of Orthopaedics, Rheumatology & Musculoskeletal Sciences, Windmill Road, Oxford OX3 7LD, UK.
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Abstract
The Oxford knee score (OKS) is a validated and widely accepted disease-specific patient-reported outcome measure, but there is limited evidence regarding any long-term trends in the score. We reviewed 5600 individual OKS questionnaires (1547 patients) from a prospectively-collected knee replacement database, to determine the trends in OKS over a ten-year period following total knee replacement. The mean OKS pre-operatively was 19.5 (95% confidence interval (CI) 18.8 to 20.2). The maximum post-operative OKS was observed at two years (mean score 34.4 (95% CI 33.7 to 35.2)), following which a gradual but significant decline was observed through to the ten-year assessment (mean score 30.1 (95% CI 29.1 to 31.1)) (p < 0.001). A similar trend was observed for most of the individual OKS components (p < 0.001). Kneeling ability initially improved in the first year but was then followed by rapid deterioration (p < 0.001). Pain severity exhibited the greatest improvement, although residual pain was reported in over two-thirds of patients post-operatively, and peak improvement in the night pain component did not occur until year four. Post-operative OKS was lower for women (p < 0.001), those aged < 60 years (p < 0.003) and those with a body mass index > 35 kg/m(2) (p < 0.014), although similar changes in scores were observed. This information may assist surgeons in advising patients of their expected outcomes, as well as providing a comparative benchmark for evaluating longer-term outcomes following knee replacement.
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Affiliation(s)
- D P Williams
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, BOTNAR Research Centre, University of Oxford, Windmill Road, Oxford OX3 7LD, UK.
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Park BK, Laverty H, Srivastava A, Antoine DJ, Naisbitt D, Williams DP. Drug bioactivation and protein adduct formation in the pathogenesis of drug-induced toxicity. Chem Biol Interact 2010; 192:30-6. [PMID: 20846520 DOI: 10.1016/j.cbi.2010.09.011] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 09/06/2010] [Accepted: 09/07/2010] [Indexed: 02/06/2023]
Abstract
Adverse drug reactions (ADRs) remain a major complication of drug therapy and can be classified as 'on-target' or 'off-target' (idiosyncratic) reactions. On-target reactions can be predicted from the known primary or secondary pharmacology of the drug and often represent an exaggeration of the pharmacological effect of the drug. In contrast, off-target adverse reactions cannot be predicted from knowledge of the basic pharmacology of the drug. The exact mechanisms of idiosyncratic drug reactions are still unclear; however it is believed that they can be initiated by chemically reactive drug metabolites. It is well known that xenobiotics can undergo metabolic bioactivation reactions which have the potential to cause cellular stress and damage. Bioactivation of drugs is thought to have the potential of initiating covalent linkages between cellular protein and drugs which can be recognised by the adaptive immune system in the absence of detectable cellular stress. This process cannot yet be predicted in pre-clinical models or discovered in clinical trials. Because of this hazard perception, the formation of chemically reactive metabolites in early drug discovery remains a serious impediment to the development of new medicines and can lead to withdrawal of an otherwise effective therapeutic agent. The fear of such reactions occurring at the post-licensing stage - when such problems first become evident - is a major contribution to drug attrition. The first step towards such methodology has been the development of chemically reactive metabolite screens. The chemical basis of drug bioactivation can usually be rationalised and synthetic strategies put in place to prevent such bioactivation. However, there is no simple correlation between drug bioactivation in vitro and adverse drug reactions in the clinic. Such a chemical approach is clearly limited by the facts that (a) not all drugs that can undergo bioactivation by human drug-metabolising enzymes are associated with hypersensitivity in the clinic and (b) drug bioactivation may not always be a mandatory step in drug hypersensitivity. To predict such reactions in early drug development, it will require an integrated understanding of the chemical, immunological and genetic basis of adverse drug reactions in patients, which in turn will depend on the development of novel in vitro experimental systems.
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Affiliation(s)
- B K Park
- MRC Centre for Drug Safety Science, Institute of Translational Medicine, Department of Molecular and Clinical Pharmacology, University of Liverpool, Sherrington Buildings, Ashton Street, Liverpool L69 3GE, UK.
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Abstract
Adverse drug reactions, in particular drug-induced hepatotoxicity, represent a major challenge for clinicians and an impediment to safe drug development. Novel blood or urinary biomarkers of chemically-induced hepatic stress also hold great potential to provide information about pathways leading to cell death within tissues. The earlier pre-clinical identification of potential hepatotoxins and non-invasive diagnosis of susceptible patients, prior to overt liver disease is an important goal. Moreover, the identification, validation and qualification of biomarkers that have in vitro, in vivo and clinical transferability can assist bridging studies and accelerate the pace of drug development. Drug-induced chemical stress is a multi-factorial process, the kinetics of the interaction between the hepatotoxin and the cellular macromolecules are crucially important as different biomarkers will appear over time. The sensitivity of the bioanalytical techniques used to detect biological and chemical biomarkers underpins the usefulness of the marker in question. An integrated analysis of the biochemical, molecular and cellular events provides an understanding of biological (host) factors which ultimately determine the balance between xenobiotic detoxification, adaptation and liver injury. The aim of this review is to summarise the potential of novel mechanism-based biomarkers of hepatic stress which provide information to connect the intracellular events (drug metabolism, organelle, cell and whole organ) ultimately leading to tissue damage (apoptosis, necrosis and inflammation). These biomarkers can provide both the means to inform the pharmacologist and chemist with respect to safe drug design, and provide clinicians with valuable tools for patient monitoring.
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Affiliation(s)
- D J Antoine
- Department of Pharmacology & Therapeutics, MRC Centre for Drug Safety Science, University of Liverpool, Liverpool, UK.
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Roberts PJ, Williams DP, Sabert H, Mangan BJ, Bird DM, Birks TA, Knight JC, Russell PSJ. Design of low-loss and highly birefringent hollow-core photonic crystal fiber. Opt Express 2006; 14:7329-7341. [PMID: 19529102 DOI: 10.1364/oe.14.007329] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A practical hollow-core photonic crystal fiber design suitable for attaining low-loss propagation is analyzed. The geometry involves a number of localized elliptical features positioned on the glass ring that surrounds the air core and separates the core and cladding regions. The size of each feature is tuned so that the composite core-surround geometry is antiresonant within the cladding band gap, thus minimizing the guided mode field intensity both within the fiber material and at material/air interfaces. A birefringent design, which involves a 2-fold symmetric arrangement of the features on the core-surround ring, gives rise to wavelength ranges where the effective index difference between the polarization modes is larger than 10(-4). At such high birefringence levels, one of the polarization modes retains favorable field exclusion characteristics, thus enabling low-loss propagation of this polarization channel.
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Affiliation(s)
- P J Roberts
- BlazePhotonics Ltd, University of Bath Campus, Claverton Down, Bath BA2 7AY, United Kingdom.
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Williams DP, Garcia-Allan C, Hanton G, LeNet JL, Provost JP, Brain P, Walsh R, Johnston GI, Smith DA, Park BK. Time course toxicogenomic profiles in CD-1 mice after nontoxic and nonlethal hepatotoxic paracetamol administration. Chem Res Toxicol 2005; 17:1551-61. [PMID: 15606129 DOI: 10.1021/tx049846x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [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: 11/30/2022]
Abstract
Adverse drug reactions are a major clinical problem. Drug-induced hepatotoxicity constitutes a large percentage of these reactions. A thorough understanding of the genetic events, specifically, the early "decision-making" processes underlying biological changes caused by drugs and metabolites, is required. To assist in the understanding of these events, we have employed the model hepatotoxin, paracetamol (APAP), and GeneChip technology to investigate global genetic events seen after nontoxic and toxic doses in the mouse. Mice were dosed [vehicle, nontoxic APAP (1 mmol/kg), and toxic APAP (3.5 mmol/kg)], and individual hepatic RNA samples were hybridized to separate chips to determine interanimal variation. Statistical analysis detected 175 CD-1 mouse genes that were significantly regulated (P < 4.1 x 10(-6)), and nonsignificant genes were discarded. For clarity, the significantly regulated genes were then binned into categories according to their major function-antioxidant, glutathione, metabolism, transcription, immune, and apoptosis. There was no hepatic stress observed after dosing 1 mmol/kg APAP, when measured by serum alanine aminotransferase levels. Hepatic toxicity was observed at both 4 and 24 h after a 3.5 mmol/kg dose of APAP. Time course expression profiles for selected genes have been created. These results demonstrate that most active gene expression occurs around 4 h after a toxic dose of APAP. Down-regulation of these genes is observed over 24 h, coinciding with the development of overt toxicity. These data provide a deeper understanding of the in vivo time course of physiological responses of the liver to chemical stress and provide a logical step forward for the investigation of new chemical entities demonstrated positive in chemically reactive metabolite screens. The complete data set can be viewed at http://www.ebi.ac.uk/arrayexpress/. The accession number is E-MEXP-82.
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Affiliation(s)
- D P Williams
- Department of Pharmacology and Therapeutics, University of Liverpool, Sherrington Building, Ashton Street, P.O. Box 147, Liverpool, Merseyside L69 3GE, United Kingdom.
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Couny F, Sabert H, Roberts P, Williams DP, Tomlinson A, Mangan B, Farr L, Knight J, Birks T, Russell PS. Visualizing the photonic band gap in hollow core photonic crystal fibers. Opt Express 2005; 13:558-563. [PMID: 19488385 DOI: 10.1364/opex.13.000558] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The light radiated from the guided mode of a hollow core photonic crystal fiber into free space is measured as a function of angle and wavelength. This enables the direct experimental visualization of the photonic band gap and the identification of localized modes of the core region.
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Williams DP, Kitteringham NR, Naisbitt DJ, Pirmohamed M, Smith DA, Park BK. Are chemically reactive metabolites responsible for adverse reactions to drugs? Curr Drug Metab 2002; 3:351-66. [PMID: 12093355 DOI: 10.2174/1389200023337423] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [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: 11/22/2022]
Abstract
Low molecular weight organic chemicals can be transformed by normal drug-metabolising systems into short-lived metabolites that are inherently reactive towards cellular macromolecules. There is direct evidence that the formation of such chemically reactive metabolites may lead to mutagenesis, carcinogenicity, apoptosis and necrosis in both cell and animal models. A number of drugs associated with non-pharmacological drug toxicities in man have been shown to undergo bioactivation either in vivo or in vitro. We have therefore examined the evidence for the role of reactive metabolites in the three most common drug-induced toxicities: hepatotoxicity, skin reactions and blood dyscrasias.
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Affiliation(s)
- D P Williams
- Department of Pharmacology and Therapeutics, The University of Liverpool, Liverpool, UK
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Abstract
Adverse drug reactions are a major clinical problem and often preclude drug administration. Drug hypersensitivity (or allergy) represents one of the most severe and unpredictable reactions associated with drug therapy. Our current understanding of drug hypersensitivity is based on the hapten hypothesis of immune recognition of drugs by T cells. The onset of hypersensitivity involves drug bioactivation, covalent binding, followed by uptake, antigen processing and T cell proliferation. There is convincing evidence that drugs associated with a high incidence of hypersensitivity are converted to protein reactive intermediates by the normal processes of drug metabolism and stimulate a cellular immune response in sensitive individuals. Until recently, however, there has been little evidence to relate the formation of a reactive metabolite to the initiation of a cellular immune response. The purpose of this review is to detail recent advances in our understanding of the complex mechanisms of drug hypersensitivity, and using severe skin reactions as an example, assess recent evidence that supports the hapten hypothesis of drug hypersensitivity.
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Affiliation(s)
- D J Naisbitt
- Department of Pharmacology and Therapeutics, University of Liverpool, Liverpool, UK.
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Snow CM, Williams DP, LaRiviere J, Fuchs RK, Robinson TL. Bone gains and losses follow seasonal training and detraining in gymnasts. Calcif Tissue Int 2001; 69:7-12. [PMID: 11685427 DOI: 10.1007/s00223-001-0014-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2000] [Accepted: 02/23/2001] [Indexed: 10/26/2022]
Abstract
The response of the human skeleton to high magnitude loading and unloading is poorly understood. Our aim was to evaluate changes in bone mineral density (BMD) in a group of intercollegiate gymnasts (n = 8, age = 18.6+/-0.8 years) over 24 months that included two 8-month competitive seasons and two 4-month offseasons. BMD of the hip, spine, and whole body was evaluated by DXA (Hologic QDR-1000/W) at baseline, 8, 12, 20, and 24 months. Results indicated significant seasonal trends in BMD of the femoral neck, trochanter, total hip, lumbar spine, and whole body. Specifically, there was a strikingly consistent pattern of bone density increases over the training seasons followed by clear declines in the offseasons. Increases at the spine were 3.5% and 3.7% followed by declines of 1.5% and 1.3% in the offseasons. Total hip BMD increased 2.3% and 1.9% during the competitive seasons followed by decreases of 1.5% and 1.2% in the offseasons. We observed a significant 24-month increase of 4.3% in spine BMD but no significant overall change at the hip. In conclusion, the human skeleton demonstrated a measurable response to high magnitude loading and unloading that was consistent across bone sites over 24 months of observation.
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Affiliation(s)
- C M Snow
- Bone Research Laboratory, Oregon State University, Corvallis 97331, USA
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Williams DP, Pirmohamed M, Naisbitt DJ, Uetrecht JP, Park BK. Induction of metabolism-dependent and -independent neutrophil apoptosis by clozapine. Mol Pharmacol 2000; 58:207-16. [PMID: 10860943 DOI: 10.1124/mol.58.1.207] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.2] [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: 11/22/2022] Open
Abstract
Clozapine, an atypical antipsychotic used in the treatment of refractory schizophrenia, causes neutropenia and agranulocytosis in 3 and 0.8% of patients, respectively. Clozapine undergoes bioactivation to a chemically reactive nitrenium ion, which has been shown to cause neutrophil cytotoxicity. To define further the mechanism of cell death, we have investigated the toxicity of clozapine, its stable metabolites, and its chemically reactive nitrenium ion to neutrophils and lymphocytes. Clozapine was able to induce neutrophil apoptosis at therapeutic concentrations (1-3 microM) only when it was bioactivated to the nitrenium ion. The parent drug caused apoptosis at supratherapeutic concentrations (100-300 microM) only. Neutrophil apoptosis induced by the nitrenium ion, but not by the parent drug itself, was inhibited by antioxidants and genistein and was accompanied by cell surface haptenation (assessed by flow cytometry) and glutathione depletion. Dual-color flow cytometry showed that neutrophils that were haptenated were the same cells that underwent apoptosis. No apoptosis of lymphocytes was evident with the nitrenium ion or the parent drug, despite the fact that the former caused cell surface haptenation, glutathione depletion, and loss of membrane integrity. Demethylclozapine, the major stable metabolite in vivo, showed a profile that was similar to, although less marked than that observed with clozapine. N-oxidation of clozapine or replacement of the nitrogen (at position 5) by sulfur produced compounds that were entirely nontoxic to neutrophils. In conclusion, the findings of the study expand on potential mechanisms of clozapine-induced cytotoxicity, which may be of relevance to the major forms of toxicity encountered in patients taking this drug.
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Affiliation(s)
- D P Williams
- Department of Pharmacology and Therapeutics, The University of Liverpool, United Kingdom.
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Gibbs MD, Reeves RA, Farrington GK, Anderson P, Williams DP, Bergquist PL. Multidomain and multifunctional glycosyl hydrolases from the extreme thermophile Caldicellulosiruptor isolate Tok7B.1. Curr Microbiol 2000; 40:333-40. [PMID: 10706665 DOI: 10.1007/s002849910066] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [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: 11/25/2022]
Abstract
DNA sequencing techniques have revealed widespread molecular diversity of the genomic organization of apparently closely related bacteria (as judged from SSU rDNA sequence similarity). We have previously described the extreme thermophile Caldicellulosiruptor saccharolyticus, which is unusual in possessing multi-catalytic, multidomain arrangements for the majority of its glycosyl hydrolases. We report here the sequencing of three gene clusters of glycosyl hydrolases from Caldicellulosiruptor sp. strain Tok7B.1. These clusters are not closely linked, and each is different in its organization from any described for Cs. saccharolyticus. The catalytic domains of the enzymes belong to glycosyl hydrolase families 5, 9, 10, 43, 44, and 48. The cellulose binding domains (CBDs) of these enzymes from Caldicellulosiruptor sp. Tok7B.1 are types IIIb, IIIc, or VI. A number of individual catalytic and binding domains have been expressed in Escherichia coli, and biochemical data are reported on the purified enzymes for cellulose degradation encoded by engineered derivatives of celB and celE.
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Affiliation(s)
- M D Gibbs
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
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Abstract
Interest in lipases from microorganisms, animals, and plants has greatly increased in the past decade due to their applications in biotransformations and organic syntheses. We are reporting the purification and characterization of two lipases from the fungus, Ophiostoma piliferum, a saprophytic organism commonly found on wood. A major and a minor lipase have been co-purified by hydrophobic interaction chromatography on octyl sepharose FF, followed by ion exchange chromatography on Q sepharose FF. The lipases bound very tightly to octyl sepharose resulting in greater than 100-fold purification in this one step. The major lipase has a molecular weight of approximately 60 kDa, a pI of 3.79, and is glycosylated as determined by PAS staining. The minor lipase, which composes 10% of the total protein, has a pI of 3.6, and molecular weight of approximately 52 kDa and did not stain with the PAS reagent. Deglycosylation of the major lipase produced two proteins of lower molecular weight, a 55 kDa protein and a 52 kDa protein. The deglycosylated protein at 52 kDa co-migrates with the minor lipase on SDS-PAGE gels. N-terminal amino acid sequencing of the major and minor lipases indicated both lipases have the same N-termini and MALDI-TOF mass spectral analysis showed similar peptide patterns. Available data indicate that the lipases are derived from the same protein and appear to differ in their post-translational modification as evidenced by their pIs and molecular weight difference. The pH rate profile and thermal stability were determined for the purified O. piliferum lipase and were consistent with a mesophilic lipase. In aqueous solution, the lipases exhibited a higher rate of hydrolysis for p-nitrophenylbutyrate (C4) than for p-nitrophenylstearate (C18), which is an unexpected result.
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Affiliation(s)
- T S Brush
- Clariant Corporation, Biotechnology Research Division, Lexington, MA 02421, USA.
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Naisbitt DJ, Williams DP, O'Neill PM, Maggs JL, Willock DJ, Pirmohamed M, Park BK. Metabolism-dependent neutrophil cytotoxicity of amodiaquine: A comparison with pyronaridine and related antimalarial drugs. Chem Res Toxicol 1998; 11:1586-95. [PMID: 9860505 DOI: 10.1021/tx980148k] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.7] [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: 11/30/2022]
Abstract
Life-threatening agranulocytosis and hepatotoxicity during prophylactic administration of amodiaquine have led to its withdrawal. Agranulocytosis is thought to involve bioactivation to a protein-reactive quinoneimine metabolite. The toxicity of amodiaquine and the lack of cheap drugs have prompted a search for alternative antimalarial agents. The aim of this study was to determine the metabolism and neutrophil toxicity of amodiaquine, pyronaridine, and other related antimalarial agents. Horseradish peroxidase and hydrogen peroxide were used to activate drugs to their respective quinoneimine metabolites. Metabolites were trapped as stable glutathione conjugates, prior to analysis by LC/MS. Amodiaquine was metabolized to a polar metabolite (m/z 661), identified as a glutathione adduct. Tebuquine was converted to two polar metabolites. The principal metabolite (m/z 686) was derived from glutathione conjugation and side chain elimination, while the minor metabolite gave a protonated molecule (m/z 496). Only parent ions were identified when chloroquine, cycloquine, or pyronaridine was incubated with the activating system and glutathione. Calculation of the heat of formation of the drugs, however, demonstrated that amodiaquine, tebuquine, cycloquine, and pyronaridine readily undergo oxidation to their quinoneimine. None of the antimalarial compounds depleted the level of intracellular glutathione (1-300 microM) when incubated with neutrophils alone. Additionally, with the exception of tebuquine, no cytotoxicity below 100 microM was observed. In the presence of the full activating system, however, all compounds except chloroquine resulted in depletion of the level of glutathione and were cytotoxic. Pretreating the cells with glutathione and other antioxidants inhibited metabolism-dependent cytotoxicity. In summary, our data show that amodiaquine and related antimalarials containing a p-aminophenol moiety undergo bioactivation in vitro to chemically reactive and cytotoxic intermediates. In particular, pyronaridine, which is currently being investigated in humans, was metabolized to a compound which was toxic to neutrophils. Thus, the possibility that it will cause agranulocytosis in clinical practice cannot be excluded, and will require careful monitoring.
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Affiliation(s)
- D J Naisbitt
- Department of Pharmacology and Therapeutics, The University of Liverpool, P.O. Box 147, Liverpool L69 3BX, U.K
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20
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Williams DP, Pirmohamed M, Naisbitt DJ, Maggs JL, Park BK. Neutrophil cytotoxicity of the chemically reactive metabolite(s) of clozapine: possible role in agranulocytosis. J Pharmacol Exp Ther 1997; 283:1375-82. [PMID: 9400013] [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: 02/05/2023] Open
Abstract
Clozapine is associated with a 0.8% incidence of agranulocytosis. Bioactivation to an unstable protein-reactive metabolite, identified as a nitrenium intermediate, has been implicated in the toxicity. In this study, we investigated whether the reactive metabolite is cytotoxic toward polymorphonuclear leukocytes and mononuclear leukocytes using horseradish peroxidase and H2O2 to generate the metabolite in situ. In the absence of a full metabolizing system (i. e., lack of horseradish peroxidase and/or H2O2), clozapine (0-100 microM) and its stable metabolites were not cytotoxic. With a full metabolizing system, both clozapine (30 microM) and demethylclozapine exhibited cytotoxicity toward polymorphonuclear leukocytes (50.7 +/- 7.7% and 17.6 +/- 1.2% cell death, respectively) and mononuclear leukocytes (36.6 +/- 2.1% and 24.6 +/- 4.1%, respectively), whereas clozapine N-oxide was not cytotoxic. Exogenous glutathione (GSH), N-acetylcysteine and ascorbic acid all protected the cells. Bioactivation of clozapine and demethylclozapine, but not the N-oxide, was accompanied by depletion of intracellular GSH. [14C]Clozapine was metabolized to the previously identified C6 and C9 glutathionyl conjugates; GSH conjugates were also detected when demethylclozapine and clozapine N-oxide were bioactivated by horseradish peroxidase and H2O2. In conclusion, using a novel in vitro assay, we have shown that clozapine and its stable metabolites are not cytotoxic per se but are bioactivated to cytotoxic metabolites. The cytotoxic metabolite of clozapine is identical to the protein-reactive metabolite that has been characterized previously. These cytotoxic metabolites may play an important role in the pathogenesis of clozapine agranulocytosis; the mechanism by which this occurs is currently being investigated.
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Affiliation(s)
- D P Williams
- Department of Pharmacology and Therapeutics, University of Liverpool, Liverpool L69 3BX, UK
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Longo SR, Williams DP. Bilateral fascia iliaca catheters for postoperative pain control after bilateral total knee arthroplasty: A case report and description of a catheter technique†. Reg Anesth Pain Med 1997; 22:372-7. [PMID: 9223205 DOI: 10.1016/s1098-7339(97)80014-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [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: 10/23/2022]
Abstract
BACKGROUND AND OBJECTIVES The pain following total knee arthroplasty can be associated with significant morbidity, especially in the elderly. Regional anesthetic techniques attenuate or eliminate postoperative pain, which may reduce this morbidity. METHODS A 74-year-old patient with history of an epidural abscess underwent elective bilateral total knee arthroplasty for degenerative joint disease. Bilateral lumbar plexus catheters were placed via the fascia iliaca compartments. Lidocaine was infused postoperative through both catheters, and serum lidocaine levels were followed. RESULTS The patient received significant postoperative pain relief based on physical and subjective examination. There were no complications or untoward effects related to the technique. CONCLUSION Lumbar plexus blockade with continuous local anesthetic infusion via the fascia iliaca compartment is an effective means of providing postoperative analgesia after total knee arthroplasty when epidural analgesia is contraindicated.
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Affiliation(s)
- S R Longo
- Department of Anesthesia, Pennsylvania State University, Milton S. Hershey Medical Center, Hershey 17033, USA
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Wilson AS, Williams DP, Davis CD, Tingle MD, Park BK. Bioactivation and inactivation of aflatoxin B1 by human, mouse and rat liver preparations: effect on SCE in human mononuclear leucocytes. Mutat Res 1997; 373:257-64. [PMID: 9042408 DOI: 10.1016/s0027-5107(96)00205-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [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: 02/03/2023]
Abstract
The purpose of this study was to investigate the use of human and animal subcellular liver fractions in an in vitro evaluation of carcinogenic risk. The bioactivation and bioinactivation of the known genotoxic carcinogen aflatoxin B1 by human, mouse and rat liver preparations was investigated using the SCE assay in human lymphocytes as a genotoxic endpoint. There was a 10-fold variation in SCE response (1.1-11.6 SCE/Cell) in human mononuclear leucocytes (MNLs) after aflatoxin B1 was activated by human liver microsomes (n = 6). Activation correlated with the CYP1A2 phenotype of livers (r = 0.8; p < 0.05), but there was no correlation with either GST M1 genotype or epoxide hydrolase phenotype. Mouse liver microsomes activated aflatoxin B1 to a greater extent [(1 micro M) 12.8 +/- 2.51 SCE/Cell] than either rat [(10 micro M) 12.0 +/- 3.84 SCE/Cell or human (L25) [(10 micro M) 8.8 +/- 2.00 SCE/Cell liver microsomes. The addition of mouse liver cytosol and reduced glutathione (GSH) significantly (p < 0.001) reduced aflatoxin B1-dependent genotoxicity, whereas the addition of either human or rat cytosol (+GSH) was without effect. These data indicate that species variation in both bioactivation and bioinactivation can exist. Therefore there is a necessity for careful selection of activation systems from species whose biochemical profile reflects that of man.
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Affiliation(s)
- A S Wilson
- Department of Pharmacology and Therapeutics, University of Liverpool, UK
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Abstract
The toxicity of naphthalene and its metabolites has been investigated in vitro. Both naphthalene and its metabolite 1-naphthol were bioactivated by human hepatic microsomes to metabolite(s) which were toxic to mononuclear leucocytes (MNL). However 1-naphthol was more cytotoxic than naphthalene (49.8 +/- 13.9% vs. 19.0 +/- 10.0% cell death; P < 0.01), indicating that the toxicity of naphthalene is dependent on the bioactivation of 1-naphthol. CYP2E1-induced rat liver microsomes increased metabolism of naphthalene by 13% compared to control microsomes with a concomitant increase in both 1-naphthol and dihydrodiol formation. The cytotoxicity of naphthalene but not of 1-naphthol was increased by CYP2E1 induction, indicating that separate enzymes are involved in the bioactivation of 1-naphthol. The metabolites of 1-naphthol, 1,2-naphthoquinone (51.4 +/- 6.6% cell death) and 1,4-naphthoquinone (49.1 +/- 3.4% cell death) were directly toxic to MNL and depleted glutathione to 1.0% of the control levels. Both quinones were also genotoxic to human lymphocytes. In contrast, the primary metabolite of naphthalene, the 1,2-epoxide (0-100 microM) was neither cytotoxic nor genotoxic, and did not deplete glutathione. In conclusion, our data suggests that the cytotoxicity and genotoxicity of naphthalene is associated with the formation of quinones from 1-naphthol rather than naphthalene-1,2-epoxide.
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Affiliation(s)
- A S Wilson
- Department of Pharmacology and Therapeutics, University of Liverpool, UK
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Williams DP, Going SB, Milliken LA, Hall MC, Lohman TG. Practical techniques for assessing body composition in middle-aged and older adults. Med Sci Sports Exerc 1995; 27:776-83. [PMID: 7674884] [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: 01/26/2023]
Abstract
The purpose of this study was to compare the relationships of anthropometric, bioelectrical impedance analysis (BIA), and near infrared interactance (NIR) measurements with a multiple-component (MC) criterion estimate of body composition derived from body density (D), body water (W), and bone mineral (B) in 48 white adults aged 49-80 yr. Relative errors of predicting the MC criterion from the practical measurements were determined by simple regressions within gender and calculated as the SEE divided by the criterion mean and expressed as a percentage. Relative errors were lowest for the BIA variable, height2/resistance (4.8-5.0%), higher for body mass index and the sum of 10 skinfold thicknesses (7.0-14.5%), and highest for NIR-derived optical density readings at the biceps and the sum of 10 sites (10.8-15.8%). Due to the low relative prediction error for height2/resistance, sex-specific BIA formulas for estimating fat-free mass from D, W, and B (FFM-DWB) were developed. The SEEs for predicting FFM-DWB from BIA, weight, and age were both 1.5 kg in women and men. Because BIA is not limited to ambulatory subjects, it is concluded that BIA may be a particularly useful, practical technique for estimating body composition in older adults.
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Affiliation(s)
- D P Williams
- Stanford Center for Research in Disease Prevention, Palo Alto, CA 94304, USA
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25
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Jabara HH, Vercelli D, Schneider LC, Williams DP, Genbauffe FS, Poisson LR, Waters CA, Geha RS. Interleukin-4 receptor expression by human B cells: functional analysis with a human interleukin-4 toxin, DAB389IL-4. J Allergy Clin Immunol 1995; 95:893-900. [PMID: 7722171 DOI: 10.1016/s0091-6749(95)70134-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [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]
Abstract
BACKGROUND Studies of human IgE-secreting B cells have proven difficult because of the small size of this population. We have used an interleukin-4 (IL-4) fusion toxin to detect functionally IL-4 receptor (IL-4R) expression on B cells involved in IgE synthesis. METHODS In diphtheria toxin IL-4 (DAB389IL-4) the receptor-binding domain of diphtheria toxin has been replaced with human IL-4. DAB389IL-4 cytotoxicity depends on IL-4R binding and internalization. RESULTS Addition of DAB389IL-4 inhibited IgE synthesis induced by IL-4+ anti-CD40 monoclonal antibody or hydrocortisone. IgE inhibition resulted from DAB389IL-4 B-cell cytotoxicity because DAB389IL-4 inhibited IL-4-independent B-cell proliferation. Thus induction of human IgE synthesis involves IL-4R+ cells. In contrast, terminally differentiated, IgE-producing B cells no longer express functional IL-4R because DAB389IL-4 only modestly inhibited ongoing IgE synthesis by B cells from patients with hyper-IgE states and only minimally affected IL-4-induced IgE synthesis in normal B cells when the toxin was added at day 7. Pokeweed mitogen-induced IgM synthesis was sensitive to early but not to late addition of DAB389IL-4. Thus the loss of functional IL-4R immunoglobulin-secreting B cells is independent of isotype switching. CONCLUSIONS IgE-secreting B cells no longer express functional IL-4R. Therapies for allergic disease that target the IL-4R would not affect IgE-secreting B cells but may block the recruitment of B cells into the IgE-secreting pool. For optimal benefits this approach may be combined with therapies that target IL-4R-, IgE-secreting B cells.
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Affiliation(s)
- H H Jabara
- Division of Immunology, Children's Hospital, Boston, MA 02115, USA
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Williams DP, Going SB, Lohmon TG, Wattigney WA, Berenson GS. 990 ASSOCIATION OF CHANGES IN BODY COMPOSITION AND CHD RISK FACTORS FROM EARLY TO LATER LIFE. Med Sci Sports Exerc 1994. [DOI: 10.1249/00005768-199405001-00992] [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: 11/21/2022]
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Chadwick DE, Williams DP, Niho Y, Murphy JR, Minden MD. Cytotoxicity of a recombinant diphtheria toxin-granulocyte colony-stimulating factor fusion protein on human leukemic blast cells. Leuk Lymphoma 1993; 11:249-62. [PMID: 7505148 DOI: 10.3109/10428199309087002] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [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: 01/25/2023]
Abstract
Granulocyte colony-stimulating factor (G-CSF) is a potent stimulator of the growth of normal and malignant hematopoietic cells and synergizes with other factors such as interleukin-3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF). The action of G-CSF is mediated through a specific membrane receptor, however it is not clear if all of the effects of G-CSF are direct or indirect. As a step towards addressing this problem, a recombinant diphtheria toxin (DT)-related human G-CSF fusion protein has been constructed and purified from E. coli. The 70,000 dalton chimeric protein has immunologic determinants characteristic of both DT and G-CSF. At high concentrations, DAB486-G-CSF is cytotoxic towards G-CSF-dependent OCI/AML1 cells, but not factor independent OCI/AML3 cells; colony formation by G-CSF-responsive leukemic blasts from a patient with acute myeloblastic leukemia (AML) was also inhibited. The G-CSF fusion toxin displayed ADP-ribosyltransferase activity in a cell-free system. Genetic conjugation of G-CSF to an enzymatically inactive DT mutant, CRM197, resulted in a 200-fold reduction in the ability of G-CSF to stimulate normal bone marrow colony formation. These results suggest that fusion of G-CSF to DT sequences interferes with some of the activity but not the specificity of the ligand binding domain of the molecule. Nevertheless, DAB486-G-CSF may be included with the increasing number of other toxin-hormone fusion proteins whose toxicity is directed towards specific receptor-bearing cells, and may represent a novel approach towards the study and treatment of leukemia.
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Affiliation(s)
- D E Chadwick
- Division of Molecular and Cell Biology, Ontario Cancer Institute, Toronto, Canada
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28
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Hewitt MJ, Going SB, Williams DP, Lohman TG. Hydration of the fat-free body mass in children and adults: implications for body composition assessment. Am J Physiol 1993; 265:E88-95. [PMID: 8338157 DOI: 10.1152/ajpendo.1993.265.1.e88] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Previous studies have shown that children have a higher aqueous fraction of the fat-free body mass (FFM) than young adults. In older adults, methodological differences among studies limit evaluation of potential age-related differences in the water content of the FFM (W/FFM). Therefore, we determined W/FFM in 28 healthy white prepubescent children (age = 5-10 yr), 31 young adults (age = 22-39 yr), and 62 older adults (age = 65-84 yr), using 2H2O dilution to estimate total body water and a multicomponent approach based on body density, total body water, and regional bone mineral density to estimate FFM. To quantify the extent to which variation in W/FFM affects percent fat estimation error, differences in percent fat between our multicomponent approach and the Siri two-component model were related to W/FFM. Prepubescent children (72.7 +/- 1.6%) and older adults (72.5 +/- 1.4%) were found to have significantly higher (P < 0.01) mean W/FFM than young adults (70.8 +/- 1.2%). Differences in percent fat between the multicomponent and two-component models ranged from -10 to 6% fat and were significantly associated with W/FFM (r = -0.62, P < 0.0001). We conclude that prepubescent children and older adults, on average, have a higher W/FFM than young adults, and that, in adults, individual differences in W/FFM account for a substantial portion of the percent fat estimation errors associated with the use of two-component body composition models.
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Affiliation(s)
- M J Hewitt
- Department of Exercise and Sport Sciences, University of Arizona, Tucson 85721
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Williams DP, Boyden TW, Pamenter RW, Lohman TG, Going SB. Relationship of body fat percentage and fat distribution with dehydroepiandrosterone sulfate in premenopausal females. J Clin Endocrinol Metab 1993; 77:80-5. [PMID: 8325963 DOI: 10.1210/jcem.77.1.8325963] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Dehydroepiandrosterone (DHEA) has an antiobesity effect in rodents, and elevated endogenous levels of its sulfate ester (DHEAS) are associated with reductions in risk for cardiovascular disease (CVD) in men. To examine the association of body fat and fat distribution, established correlates of CVD and CVD risk factors, with circulating DHEAS levels in women, we measured trunk and limb skinfold thicknesses and circumferences, total and regional body fat from dual energy x-ray absorptiometry (DXA), and serum levels of DHEAS in 96 healthy Caucasian females aged 28-39 yr. Body mass index, percentage fat from DXA and the waist-to-hip ratio were not significantly correlated (r < or = 0.15, P > or = 0.156) with serum DHEAS levels, regardless of statistical control for age, smoking behavior, and fasting status. However, the ratio of trunk/total skinfold thicknesses (r = 0.23, P = 0.030) and the percentage of total fat located on the trunk from DXA (r = 0.32, P = 0.002) were positively correlated with DHEAS, whereas the ratio of leg/total skinfold thicknesses (r = -0.25, P = 0.015) and the percentage of total fat located on the legs from DXA (r = -0.25, P = 0.015) were inversely correlated with DHEAS after adjusting for age, smoking, and fasting status. With the exception of the trunk/total skinfold thickness ratio, the correlations of DXA- and skinfold-derived estimates of fat distribution remained significant (P < or = 0.033) even after further adjustment for percentage fat or body mass index. It is concluded that increased amounts of total fat located on the trunk and decreased amounts of total fat located on the legs are associated with increased serum DHEAS concentrations in normally menstruating females.
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Affiliation(s)
- D P Williams
- Department of Exercise and Sport Sciences, University of Arizona, Tucson 85721
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Going SB, Massett MP, Hall MC, Bare LA, Root PA, Williams DP, Lohman TG. Detection of small changes in body composition by dual-energy x-ray absorptiometry. Am J Clin Nutr 1993; 57:845-50. [PMID: 8503351 DOI: 10.1093/ajcn/57.6.845] [Citation(s) in RCA: 122] [Impact Index Per Article: 3.9] [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: 01/31/2023] Open
Abstract
The ability of dual-energy x-ray absorptiometry (DEXA) to detect small changes in body composition was studied in 17 men and women during a dehydration-rehydration protocol. Scale weight (BW) and total mass (TM) from DEXA were highly related (r > 0.99) as were estimates of fat-free mass (r = 0.99) and percent fat (r = 0.97) from DEXA and densitometry. Changes in BW of approximately 1.5 kg due to fluid loss and gain were highly correlated (r = 0.90) with both changes in TM and soft-tissue mass (STM) by DEXA but less so (r = 0.67) with changes in lean-tissue mass (LTM). Mean changes in TM, STM, and LTM were not different (P > 0.05) from changes in BW. Estimates of bone mass and fat were unaffected by changes in hydration. We conclude that DEXA is able to detect small individual changes in TM and STM and is also useful for detecting group changes in LTM.
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Affiliation(s)
- S B Going
- Department of Exercise and Sport Sciences, University of Arizona, Tucson 85721
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Williams DP, Boyden TW, Pamenter RW, Lohman TG, Going SB. 35 RELATIONSHIP OF BODY FAT PERCENTAGE AND FAT DISTRIBUTION WITH DEHYDROEPIANDROSTERONE SULFATE IN PREMENOPAUSAL FEMALES. Med Sci Sports Exerc 1993. [DOI: 10.1249/00005768-199305001-00036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Williams DP, Going SB, Massett MP, Lohman TG, Bare LA, Hewitt MJ. Aqueous and mineral fractions of the fat-free body and their relation to body fat estimates in men and women aged 49-82 years. Basic Life Sci 1993; 60:109-13. [PMID: 8110088 DOI: 10.1007/978-1-4899-1268-8_25] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- D P Williams
- Department of Exercise and Sport Sciences, University of Arizona, Tucson 85721
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Landgraf BE, Goldstein B, Williams DP, Murphy JR, Sana TR, Smith KA, Ciardelli TL. Recombinant interleukin-2 analogs. Dynamic probes for receptor structure. J Biol Chem 1992; 267:18511-9. [PMID: 1526987] [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: 12/27/2022] Open
Abstract
Interleukin-2 (IL-2) and its receptor complex have become one of the most studied members of a growing family of protein hormones characterized by structural similarities in both ligands and their receptors. Structure-function studies of IL-2 have been complicated by the multimeric nature of its receptor. Two receptor subunits (55- and 75-kDa type I cell surface proteins) can participate to form the high affinity binding site. Although the IL-2 is apparently unique in some respects, similar subunit cooperativity has now been shown to be a common feature for other members of this receptor family. The availability of cell lines expressing the individual IL-2 receptor subunits has allowed detailed analysis of subunit binding characteristics. Results regarding the relationship of molecular recognition at each subunit to the mechanism of ligand binding at the high affinity site, however, have led to different interpretations. In this study we have employed previously prepared C-terminal IL-2 mutant proteins to examine receptor binding at all three classes using a variety of equilibrium and kinetic techniques. These results indicate that the high affinity IL-2 receptor complex includes the p55/p75 heterodimer prior to IL-2 binding and that both receptor subunits participate simultaneously in ligand capture.
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Williams DP, Going SB, Lohman TG, Harsha DW, Srinivasan SR, Webber LS, Berenson GS. Body fatness and risk for elevated blood pressure, total cholesterol, and serum lipoprotein ratios in children and adolescents. Am J Public Health 1992; 82:358-63. [PMID: 1536350 PMCID: PMC1694353 DOI: 10.2105/ajph.82.3.358] [Citation(s) in RCA: 349] [Impact Index Per Article: 10.9] [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: 12/27/2022]
Abstract
BACKGROUND Recent studies have shown considerable variation in body fatness among children and adolescents defined as obese by a percentile rank for skinfold thickness. METHODS We examined the relationship between percent body fat and risk for elevated blood pressure, serum total cholesterol, and serum lipoprotein ratios in a biracial sample of 3320 children and adolescents aged 5 to 18 years. Equations developed specifically for children using the sum of subscapular (S) and triceps (T) skinfolds were used to estimate percent fat. The S/T ratio provided an index of trunkal fat patterning. RESULTS Significant overrepresentation (greater than 20%) of the uppermost quintile (UQ) for cardiovascular disease (CVD) risk factors was evident at or above 25% fat in males (32.2% to 37.3% in UQ) and at or above 30% fat in females (26.6% to 45.4% in UQ), even after adjusting for age, race, fasting status, and trunkal fat patterning. CONCLUSIONS These data support the concept of body fatness standards in White and Black children and adolescents as significant predictors of CVD risk factors. Potential applications of these obesity standards include epidemiologic surveys, pediatric health screenings, and youth fitness tests.
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Affiliation(s)
- D P Williams
- Department of Exercise and Sport Sciences, University of Arizona, Tucson 85721
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Kiyokawa T, Williams DP, Snider CE, Waters CA, Nichols JC, Strom TB, Murphy JR. Protein engineering of DAB-IL-2 fusion toxins to increase biologic potency. Ann N Y Acad Sci 1991; 636:331-9. [PMID: 1793218 DOI: 10.1111/j.1749-6632.1991.tb33463.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- T Kiyokawa
- Evans Department of Clinical Research, Boston University Medical Center, Massachusetts 02118
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Abstract
Paul Ehrlich first suggested the simple and elegant concept of creating specific cell toxins or "magic bullets" through the fusion of cell-specific antibodies and toxins. In practice it has proven difficult to create safe and effective "magic bullets." In the past several years, several immunotoxins have been applied to clinical testing. These immunotoxins have been created by the biochemical coupling of cell- or lineage-specific monoclonal antibodies to plant toxins or fragments thereof. These immunotoxins have been used to treat bone marrow transplant recipients and patients with autoimmune disorders. In recent years, another strategy has also been pursued to create hybrid toxins. Rather than use antibodies as the targeting moiety, cytokines have been used to target a select population of cells bearing a high copy number of receptors for the specific cytokine. Rather than biochemically couple a cytokine to the toxin, the cytokine and toxin are fused by a peptide bond established via genetic engineering. A prototype IL-2 diphtheria toxin-related fusion protein is now being tested in the clinic for treatment of hematopoietic malignancies and autoimmune disorders.
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Affiliation(s)
- T B Strom
- Department of Medicine, Beth Israel Hospital, Harvard Medical School, Boston, Massachusetts 02215
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Kiyokawa T, Williams DP, Snider CE, Strom TB, Murphy JR. Protein engineering of diphtheria-toxin-related interleukin-2 fusion toxins to increase cytotoxic potency for high-affinity IL-2-receptor-bearing target cells. Protein Eng 1991; 4:463-8. [PMID: 1881872 DOI: 10.1093/protein/4.4.463] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We have used site-directed insertion and point mutagenesis in an attempt to increase the cytotoxic potency and receptor-binding affinity of the diphtheria-toxin-related interleukin-2 (IL-2) fusion toxins. Previous studies have demonstrated that both the DAB486-IL-2 and DAB389-IL-2 forms of the fusion toxin consist of three functional domains: the N-terminal fragment-A-associated ADP-ribosyltransferase, the hydrophobic-membrane-associating domains, and the C-terminal receptor-binding domain of human IL-2. By insertion mutagenesis we have increased the apparent flexibility of the polypeptide chain between the membrane-associating domains and the receptor-binding domain of this fusion toxin. In comparison to DAB486-IL-2, the cytotoxic potency of the insertion mutants was increased by approximately 17-fold for high-affinity IL-2-receptor-bearing cell lines in vitro. Moreover, competitive displacement experiments using [125I]rIL-2 demonstrate that the increase in cytotoxic potency correlates with an increase in receptor-binding affinity for both the high and intermediate forms of the IL-2 receptor.
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Affiliation(s)
- T Kiyokawa
- Evans Department of Clinical Research, University Hospital, Boston, MA 02118
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38
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Landgraf BE, Williams DP, Murphy JR, Smith KA, Ciardelli TL. Conformational perturbation of interleukin-2: a strategy for the design of cytokine analogs. Proteins 1991; 9:207-16. [PMID: 2006138 DOI: 10.1002/prot.340090306] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [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: 12/29/2022]
Abstract
Interleukin-2 (IL-2) is a representative of a growing family of small proteins termed lymphokines which are responsible for mediating cell differentiation, growth and function in the immune system. Many of these proteins are being evaluated for their clinical potential. From the perspective of drug development, structure-function analysis of these molecules and their receptors require the use methodologies different than those traditionally employed for small peptides and other natural products. However, similar pharmacologic principles apply and an understanding of ligand-receptor interactions and the associated responses is required in order to efficiently pursue agonist and antagonist design. Although IL-2 is a protein of only 133 amino acid residues for which a low resolution X-ray structure does exist, the complexity of its receptor system has provided an added challenge to structure-function studies. Consequently, little is known concerning the receptor contact residues for this protein. We have attempted to utilize established principles of protein and peptide structure to manipulate the conformation of IL-2 in a manner which has provided analogs helpful for receptor interaction studies. These proteins have not only providing useful information on the nature of the IL-2 receptor but have also revealed potential strategies for the design of IL-2 agonists and antagonists.
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Affiliation(s)
- B E Landgraf
- Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, New Hampshire 03756
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39
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Williams DP, Wen Z, Watson RS, Boyd J, Strom TB, Murphy JR. Cellular processing of the interleukin-2 fusion toxin DAB486-IL-2 and efficient delivery of diphtheria fragment A to the cytosol of target cells requires Arg194. J Biol Chem 1990; 265:20673-7. [PMID: 2243114] [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: 12/30/2022] Open
Abstract
We have used site-directed mutagenesis to examine the role played by Arg191, Arg193, and Arg194 of the fusion toxin DAB486-IL-2 in the intoxication of high affinity interleukin-2 receptor-bearing T-lymphocytes. These arginine residues are positioned in the proteolytically sensitive 14-amino acid loop subtended by the disulfide bond between Cys187 and Cys202 in this fusion toxin. DAB486-IL-2 was formed by the genetic substitution of the native diphtheria toxin receptor binding domain with human interleukin-2 (Williams, D.P., Parker, K., Bacha, P., Bishai, W., Borowski, M., Genbauffe, F., Strom, T.B., and Murphy, J.R. (1987) Protein Eng. 1, 493-498). We demonstrate that substitution of Arg194 with Gly results in a 1000-fold loss of DAB486-IL-2 potency. Since trypsin "nicking" of the Gly194 mutant restores biologic activity, we conclude that Arg194 is required for the cellular processing of the fusion toxin which results in the release of fragment A into the cytosol.
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Affiliation(s)
- D P Williams
- Evans Department of Clinical Research, Boston University Medical Center, Massachusetts 92118
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40
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Strom TB, Anderson PL, Rubin-Kelley VE, Williams DP, Kiyokawa T, Murphy JR. Immunotoxins and cytokine toxin fusion proteins. Semin Immunol 1990; 2:467-79. [PMID: 2104283] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Paul Ehrlich first suggested the simple and elegant concept of creating specific cell toxins or 'magic bullets' through the fusion of cell specific antibodies and toxins. In practice it has proven difficult to create safe and effective 'magic bullets'. In the past several years, several immunotoxins have been applied to clinical testing. These immunotoxins have been created by the biochemical coupling of cell or lineage specific monoclonal antibodies to plant toxins or fragments thereof. These immunotoxins have been used to treat bone marrow transplant recipients and patients with autoimmune disorders. In recent years, another strategy has also been pursued to create hybrid toxins. Rather than use antibodies as the targeting moiety, cytokines have been used to target a select population of cells bearing a high copy number of receptors for the specific cytokine. Rather than biochemically couple a cytokine to the toxin, the cytokine and toxin are fused by a peptide bond established via genetic engineering. A prototype IL-2 diphtheria toxin-related fusion protein is now being tested in the clinic for treatment of hematopoietic malignancies and autoimmune disorders.
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Affiliation(s)
- T B Strom
- Department of Medicine, Beth Israel Hospital, Harvard Medical School, Boston, MA 02215
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41
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Williams DP, Wen Z, Watson RS, Boyd J, Strom TB, Murphy JR. Cellular processing of the interleukin-2 fusion toxin DAB486-IL-2 and efficient delivery of diphtheria fragment A to the cytosol of target cells requires Arg194. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(17)30556-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Wszolek ZK, Williams DP, Kyle RA. Benedykt Dybowski--physician, explorer, scientist, political prisoner. Mayo Clin Proc 1990; 65:1381. [PMID: 2214885 DOI: 10.1016/s0025-6196(12)62151-x] [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: 12/30/2022]
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Williams DP, Snider CE, Strom TB, Murphy JR. Structure/function analysis of interleukin-2-toxin (DAB486-IL-2). Fragment B sequences required for the delivery of fragment A to the cytosol of target cells. J Biol Chem 1990; 265:11885-9. [PMID: 2195027] [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: 12/30/2022] Open
Abstract
We have used cassette and deletion mutagenesis to analyze the structural features of fragment B-related sequences in the fusion toxin DAB486-IL-2 (where IL-2 represents interleukin-2) that are necessary for the efficient delivery of fragment A to the cytosol of target cells. We demonstrate that whereas an intact disulfide bond between Cys461 and Cys471 may be required for the cytotoxic action of native diphtheria toxin, this bond is not required for the cytotoxic action of DAB486-IL-2. The in-frame deletion of the 97 amino acids from Thr387 to His485 of DAB486-IL-2 increases both the potency and the apparent dissociation constant (Kd) of the resulting fusion toxin for high affinity interleukin-2 receptor-bearing target cells. In contrast, the inframe deletion of either the 191 amino acids between Asp291 and Gly483 or the 85 amino acids between Asn204 and Ile290 results in a 1000-fold loss in potency. These regions contain the putative membrane-spanning regions and the amphipathic membrane surface-associating regions of fragment B, respectively. These results indicate that the efficient delivery of the ADP-ribosyltransferase from DAB486-IL-2 to the cytosol requires the membrane-associating domains of fragment B. This function has been postulated to play a role in the diphtherial intoxication of eukaryotic cells. However, unlike native diphtheria toxin, fragment B sequences distal to Thr387 do not enhance the potency of DAB486-IL-2.
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Affiliation(s)
- D P Williams
- Evans Department of Clinical Research, Boston University Medical Center, Massachusetts 02118
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Carney MD, Tessler HH, Peyman GA, Goldberg MF, Williams DP. Sympathetic ophthalmia and subretinal neovascularization. Ann Ophthalmol 1990; 22:184-6. [PMID: 2369029] [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] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We report a case of sympathetic ophthalmia with subretinal neovascularization of the macula. The subretinal neovascularization developed after penetrating trauma to the fellow eye. The occurrence of subretinal neovascularization in sympathetic ophthalmia is not surprising since disintegrative changes and breaks in Bruch's membrane have been reported in sympathetic ophthalmia. Subretinal neovascularization has also been reported in Vogt-Koyanagi-Harada syndrome, which is histopathologically similar to sympathetic ophthalmia.
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45
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Dever GE, Thomson CD, Williams DP, Kornegay DD. Physician supply and distribution in Georgia. J Med Assoc Ga 1989; 78:553-7. [PMID: 2769102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Physician supply in Georgia must be considered an urgent issue. Several important points must be recognized and addressed. The lowest physicians rates are in the more rural county population groupings. The only county population grouping with a surplus of physicians is in the over 150,000 population. The majority of physicians are concentrated in the metropolitan counties. Sixteen percent of all physicians practice in the 134 counties having less than 50,000 population. The majority of physicians are in primary care specialties. Family practice is the most dominant specialty in rural areas. By the year 2000, Georgia can expect to add 5,600 physicians due to growth. By the year 2000, Georgia can expect to lose 2,600 physicians due to retirement. Family practitioners are the most uniformly distributed of the specialties examined. They are also the specialty most needed. The average age of Georgia physicians is 46. General surgeons are in the oldest average age group (50), whereas internists are in the youngest (44). Older physicians are concentrated in the more rural areas. A significant number of all physicians are over age 55. The majority of these will be retired by the year 2000. Physicians over age 65 represent 9.2% of all physicians from the survey. In Georgia, 13.6% of all physicians were Foreign Medical School Graduates. They tend to locate their practices in medically underserved areas. The specialty choices most frequently favored by FMGs are: pediatrics, internal medicine, family practice, and obstetrics/gynecology. A total of 71.2% of all physicians accept Medicare patients; 83.8% accept Medicare patients. Ninety-two percent of all obstetricians accept obstetric patients, but this participation is threatened by problems with malpractice insurance.
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46
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Williams DP, Regier D, Akiyoshi D, Genbauffe F, Murphy JR. Design, synthesis and expression of a human interleukin-2 gene incorporating the codon usage bias found in highly expressed Escherichia coli genes. Nucleic Acids Res 1988; 16:10453-67. [PMID: 3060845 PMCID: PMC338917 DOI: 10.1093/nar/16.22.10453] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.5] [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: 01/03/2023] Open
Abstract
A synthetic gene encoding human interleukin-2 (IL-2) was designed such that the codon usage bias resembled that found in highly expressed Escherichia coli genes. The percentage of preferred codons was increased from 43% in the native cDNA sequence to 85% in the synthetic sequence. The cDNA and synthetic IL-2 genes were placed under the control of the trc promoter and expressed in E. coli JM101. While Northern blot analysis of IL-2 mRNA from each genetic construct demonstrated equivalent message half-lives, immunoblot and bioactivity analyses showed the synthetic gene to direct the synthesis of up to 16 times more IL-2 than the native cDNA sequence.
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Affiliation(s)
- D P Williams
- Evans Department of Clinical Research, University Hospital, Boston, MA
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Abstract
Two patients who were treated with lithium for psychiatric illness developed primary position downbeat nystagmus. Previous reports have suggested that lithium causes this type of nystagmus, but other known causes were present in most cases. Several months after stopping the lithium, one patient had marked resolution, while the second patient had only minimal improvement. Valproate sodium proved to be useful in suppressing the nystagmus in the second patient. Lithium carbonate is a cause of primary position downbeat nystagmus. The nystagmus may be permanent or require several months of abstinence for improvement.
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Affiliation(s)
- D P Williams
- Department of Neurology, Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, NC 27103
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48
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Bacha P, Williams DP, Waters C, Williams JM, Murphy JR, Strom TB. Interleukin 2 receptor-targeted cytotoxicity. Interleukin 2 receptor-mediated action of a diphtheria toxin-related interleukin 2 fusion protein. J Exp Med 1988; 167:612-22. [PMID: 3126255 PMCID: PMC2188856 DOI: 10.1084/jem.167.2.612] [Citation(s) in RCA: 193] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The IL-2 toxin-mediated inhibition of protein synthesis in high affinity IL-2-R-positive murine and human T cell lines has been examined. Both excess free IL-2 and mAb to the Tac epitope of the p55 subunit of IL-2-R are shown to block the action of IL-2 toxin; whereas, agents that interact with other receptors or antigens on the T cell surface have no effect. We show that IL-2 toxin, like diphtheria toxin, must pass through an acidic vesicle in order to intoxicate target T cells. Finally, we demonstrate that the IL-2 toxin-mediated inhibition of protein synthesis in both human and murine T cells that bear the high affinity IL-2-R is due to the classic diphtheria toxin fragment A-catalyzed ADP ribosylation of elongation factor 2.
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Affiliation(s)
- P Bacha
- Seragen, Inc., Hopkinton, Massachusetts 01748
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49
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Murphy JR, Williams DP, Bacha P, Bishai W, Waters C, Strom TB. Cell receptor specific targeted toxins: genetic construction and characterization of an interleukin 2 diphtheria toxin-related fusion protein. J Recept Res 1988; 8:467-80. [PMID: 3133472 DOI: 10.3109/10799898809049005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We have genetically replaced the diphtheria toxin receptor binding domain with a DNA insert encoding the T-cell growth factor interleukin-2 (IL-2). The toxin-related IL-2 fusion gene encodes a 70,586 dalton protein, pro-IL-2-toxin. The mature form of IL-2-toxin is exported to the periplasmic space of recombinant Escherichia coli and has a molecular weight of 68,086. IL-2-toxin has been partially purified from periplasmic extracts of recombinant E. coli, and it is shown to contain immunologic determinants intrinsic to both its diphtheria toxin and IL-2 components. The chimeric toxin is targeted toward IL-2 receptor bearing T-cells in vitro.
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Affiliation(s)
- J R Murphy
- Evans Department of Clinical Research, University Hospital, Boston, MA 02118
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50
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Williams DP, Parker K, Bacha P, Bishai W, Borowski M, Genbauffe F, Strom TB, Murphy JR. Diphtheria toxin receptor binding domain substitution with interleukin-2: genetic construction and properties of a diphtheria toxin-related interleukin-2 fusion protein. Protein Eng 1987; 1:493-8. [PMID: 3334101 DOI: 10.1093/protein/1.6.493] [Citation(s) in RCA: 166] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We have genetically replaced the diphtheria toxin receptor binding domain with a synthetic gene encoding interleukin-2 (IL-2) and a translational stop signal. The diphtheria toxin-related T-cell growth factor fusion gene encodes a 70 586-d polypeptide, pro-IL-2-toxin. The mature form of IL-2-toxin has a deduced mol. wt of 68,086 and is shown to be exported to the periplasmic compartment of Escherichia coli (pABI508), and contain immunologic determinants intrinsic to both its diphtheria toxin and IL-2 components. IL-2-toxin has been purified from periplasmic extracts of recombinant strains of E. coli (pABI508) by immunoaffinity chromatography using immobilized anti-IL-2. The purified chimeric toxin is shown to selectively inhibit protein synthesis in IL-2 receptor bearing targeted cells, whereas cell lines which do not express the IL-2 receptor are resistant to IL-2-toxin action.
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Affiliation(s)
- D P Williams
- Evans Department of Clinical Research, University Hospital, Boston University Medical Center, MA 02118
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