ABSTRACT
: Objective : To provide contemporary data on cancer mortality rates within the context of incidence in the population with intellectual disabilities. : Methods : Scotland's 2011 Census was used to identify adults with intellectual disabilities and controls with records linked to the Scottish Cancer Registry and death certificate data (March 2011-December 2019). The control cohort without intellectual disabilities and/or autism were used for indirect standardisation and calculation of crude incident rates/crude mortality rates, and age-sex standardised incident rate ratios/standardised mortality ratios (SIR/SMR), with 95% CIs. : Results : Adults with intellectual disabilities were most likely diagnosed cancers of digestive, specifically colorectal (14.2%), lung (9.3%), breast (female 22.9%), body of the uterus (female 9.3%) and male genital organs (male 17.6%). Higher incident cancers included metastatic cancer of unknown primary origin (female SIR=1.70, male SIR=2.08), body of uterus (female SIR=1.63), ovarian (female SIR=1.59), kidney (female SIR=1.85) and testicular (male SIR=2.49). SMRs were higher, regardless of a higher, similar or lower incidence (female SMR=1.34, male SMR=1.07). Excess mortality risk was found for colorectal (total SMR=1.54, male SMR=1.59), kidney (total SMR=2.01 u, female SMR=2.85 u), female genital organs (SMR=2.34 (ovarian SMR=2.86 u, body of uterus SMR=2.11), breast (female SMR=1.58) and metastatic cancer of unknown primary origin (female SMR=2.50 u, male SMR=2.84). : Conclusions : Adults with intellectual disabilities were more likely to die of cancer than the general population. Reasons for this may include later presentation/diagnosis (so poorer outcomes), poorer treatment/compliance or both. Accessible public health approaches are important for people with intellectual disabilities, and healthcare professionals need to be aware of the different cancer experiences faced by this population.
Subject(s)
Intellectual Disability , Neoplasms , Humans , Scotland/epidemiology , Male , Female , Neoplasms/mortality , Neoplasms/epidemiology , Intellectual Disability/epidemiology , Intellectual Disability/mortality , Adult , Incidence , Middle Aged , Retrospective Studies , Aged , Registries , Young Adult , AdolescentABSTRACT
Radial dysplasia (RD) is a congenital upper limb birth defect that presents with changes to the upper limb anatomy, including a shortened or absent radius, bowed ulna, thumb malformations, a radially deviated hand and a range of muscle and tendon malformations, including absent or abnormally shaped muscle bundles. Current treatments to address wrist instability caused by a shortened or absent radius frequently require an initial soft tissue distraction intervention followed by a wrist stabilisation procedure. Following these surgical interventions, however, recurrence of the wrist deviation remains a common, long-term problem following treatment. The impact of the abnormal soft connective tissue (muscle and tendon) anatomy on the clinical presentation of RD and the complications following surgery are not understood. To address this, we have examined the muscle, fascia and the fascial irregular connective tissue (ICT) fibroblasts found within soft connective tissues, from RD patients. We show that ICT fibroblasts isolated from RD patients are functionally abnormal when compared to the same cells isolated from control patients and secrete a relatively disordered extracellular matrix (ECM). Furthermore, we show that ICT fibroblast dysfunction is a unifying feature found in RD patients, even when the RD clinical presentation is caused by distinct genetic syndromes.
Subject(s)
Connective Tissue , Fibroblasts , Muscle, Skeletal , Humans , Fibroblasts/pathology , Connective Tissue/pathology , Muscle, Skeletal/abnormalities , Muscle, Skeletal/pathology , Male , Female , Radius/abnormalities , Radius/pathologyABSTRACT
INTRODUCTION: Cabotegravir and rilpivirine (CAB+RPV long-acting (LA)) is recommended as a treatment for HIV-1 allowing people living with HIV to receive 2 monthly injectable treatment, rather than daily pills. Providing injectable therapy in a system designed to provide and manage study participants on oral treatments poses logistical challenges namely how resources are used to accommodate patient preference within constrained health economies with capacity limitations. In this pragmatic multicentre study, we aim to understand the implementation of CAB-RPV-LA administration in two settings via mixed methods to explore perspectives of participants and the clinical team delivering CAB+RPV LA. METHODS AND ANALYSIS: Women, racially minoritised people and older people are chronically under-represented in HIV clinical trials so the ILANA trial has set recruitment caps to ensure recruitment of 50% women, 50% ethnically diverse people and 30% over 50 years of age to include a more representative study population. Using a mixed-methods approach, the primary objective is to identify and evaluate the critical implementation strategies for CAB+RPV LA in both hospital and community settings. Secondary objectives include evaluating feasibility and acceptability of CAB+RPV LA administration at UK clinics and community settings from the perspective of HIV care providers, nurses and representatives at community sites, evaluating barriers to implementation, the utility of implementation strategies and adherence. ETHICS AND DISSEMINATION: Ethical approval has been obtained from the Health Research Authority Research Ethics Committee (REC reference: 22/PR/0318). The dissemination strategy has been formulated with the SHARE Collaborative Community Advisory Board to maximise the impact of this work on clinical care and policy. This strategy draws on and leverages existing resources within the participating organisations, such as their academic infrastructure, professional relationships and community networks. The strategy will leverage the Public Engagement Team and press office to support dissemination of findings. TRIAL REGISTRATION NUMBER: NCT05294159.
Subject(s)
Anti-HIV Agents , HIV Infections , Humans , Female , Middle Aged , Aged , Male , Longitudinal Studies , HIV Infections/drug therapy , Rilpivirine/therapeutic use , Policy , United Kingdom , Anti-HIV Agents/therapeutic use , Multicenter Studies as TopicABSTRACT
BACKGROUND: This study investigated the questionable necessity of genetic testing for Fanconi anemia in children with hand anomalies. The current UK guidelines suggest that every child with radial ray dysplasia or a thumb anomaly should undergo further cost intensive investigation for Fanconi anemia. In this study we reviewed the numbers of patients and referral patterns, as well as the financial and service provision implications UK guidelines provide. METHODS: Over three years, every patient with thumb or radial ray anomaly referred to our service was tested for Fanconi Anemia. CART Analysis and machine learning techniques using Waikato Environment for Knowledge Analysis were applied to evaluate single clinical features predicting Fanconi anemia. RESULTS: Youden Index and Predictive Summary Index (PSI) scores suggested no clinical significance of hand anomalies associated with Fanconi anemia. CART Analysis and attribute evaluation with Waikato Environment for Knowledge Analysis (WEKA) showed no single feature predictive for Fanconi anemia. Furthermore, none of the positive Fanconi anemia patients in this study had an isolated upper limb anomaly without presenting other features of Fanconi anemia. CONCLUSION: As a conclusion, this study does not support Fanconi anemia testing for isolated hand abnormalities in the absence of other features associated with this blood disease.
ABSTRACT
Surgical intervention for thumb duplication can be divided into three categories: simple excision of the accessory thumb, excision of the accessory thumb with reconstruction from available "spare parts," and combining the two thumbs into one, as described by Bilhaut. This prospectively PROSPERO registered systematic review evaluates the overall, aesthetic and functional outcomes for the latter two options (reconstruction from spare parts vs. combining two thumbs into one), aiming to facilitate evidence-based decision making when addressing thumb duplication and direct future research. The review was performed in accordance with the Cochrane Handbook of Systematic Reviews and PRISMA statement. Embase, PubMed, Medline, and Cochrane databases were systematically searched. Studies offering comparisons of techniques were included. Risk of bias was assessed using the Risk of Bias In Non-randomized Studies-of Intervention tool. The quality of the evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluation. Ten retrospective observational studies were included. Data did not consistently allow analysis by procedure type. Four studies reported similar overall outcomes between techniques, while two specifically reported poor overall outcomes for the Bilhaut procedure. Two studies reported comparatively worse aesthetic outcomes for the Bilhaut procedure with four studies reporting comparatively improved functional outcomes for this procedure. Overall, interpretation of outcomes was challenging with no patient-reported outcome measures used. The quality of the evidence was universally "very low" due to all studies being at risk of methodological bias. Based on the available evidence, surgical techniques for thumb duplication correction appear comparable regarding overall outcome. There is limited evidence suggesting reconstruction with spare parts offers superior aesthetic outcomes at the expense of stability. The level of evidence is III.
ABSTRACT
BACKGROUND: Radial dysplasia (RD) is a disfiguring, potentially disabling congenital upper limb anomaly. Multiple surgical techniques are in current use, with little agreement on the optimal treatment approach. At present, no core outcome set exists specifically for RD, and the literature is dominated by retrospective case series. A recent systematic review by this group demonstrated significant heterogeneity on which outcomes are measured and how they are measured. METHODS/DESIGN: The RADIATE study will conduct a three-round online Delphi process, involving adult RD patients, the parents of children with RD, hand surgeons and hand therapists. The initial list of outcomes was drawn from our recent systematic review and will be supplemented by suggestions from the stakeholder groups. Following the Delphi process, outcomes that meet the consensus in definition will be ratified at a final consensus meeting. We will then follow the COSMIN guidelines to select outcome measurement instruments. Where appropriate, these will overlap with the outcome measures specified in the forthcoming standard set for congenital upper limb anomalies published by the International Consortium for Health Outcomes Measurement. DISCUSSION: The Radial Dysplasia Assessment, Treatment and Aetiology (RADIATE) study aims to address the uncertainty in the treatment of RD, and to begin to answer the question 'What is the most appropriate treatment of the forearm and hand for children with RD?' by establishing a core outcome set. TRIAL REGISTRATION: COMET initiative study, 902 . Registered in May 2016.
Subject(s)
Delphi Technique , Hand Deformities, Congenital/therapy , Radius/abnormalities , Adult , Aged , Clinical Protocols , Hand Deformities, Congenital/diagnosis , Hand Deformities, Congenital/etiology , Humans , Middle Aged , Outcome Assessment, Health Care , Retrospective StudiesSubject(s)
T-Box Domain Proteins/genetics , Abnormalities, Multiple/genetics , Child , Female , Gene Deletion , Heart Defects, Congenital/genetics , Heart Septal Defects, Atrial/genetics , Humans , Lower Extremity Deformities, Congenital/genetics , T-Box Domain Proteins/metabolism , Upper Extremity Deformities, Congenital/geneticsABSTRACT
OBJECTIVE: to explore student midwives' experiences of postnatal genital tract assessment within midwifery preregistration curricula. DESIGN: a single, instrumental case study design was employed involving final year student midwives. Ethical approval was gained from the Higher Education Institution at the data collection site. Sampling was purposeful and data were collected using a survey (n = 25); narrative style in depth interviews (n = 11), review of programme documentation and a student midwife / researcher data workshop. SETTING: one Higher Education Institution in the north of England. FINDINGS: three themes were identified from the data analysis, awareness of assessment methods, accessing learning opportunities and actualisation of learning. The awareness theme highlights that most students were aware of potential signs and symptoms associated with genital tract assessment and health however; difficulties were identified concerning assessment of lochia, encountering sequential assessments and recognising potential for deterioration. This awareness was influenced by access to practice based learning opportunities. Access differed due to variation in postnatal provision, service pressures and variety in mentor practices regarding selecting and creating learning opportunities. This study suggests actualisation of learning and confidence in genital tract assessment was achieved when opportunities to integrate theory and practice occurred. Actualisation was hindered by limited allocation of curriculum time specifically for postnatal maternal assessment content and assessment strategies in comparison to other aspects of midwifery knowledge. CONCLUSIONS: student midwives' experiences, awareness and learning actualisation varied in relation to the development of knowledge and confidence in maternal postnatal genital tract assessment. While clinical and theoretical learning opportunities were available, access and experience varied and limitations were identified. A number of recommendations are outlined to enhance the students learning experiences in practice and HEI settings, which address placement planning, mentor preparation, the student voice and supporting curricula documentation.
Subject(s)
Midwifery/education , Students, Nursing/psychology , Clinical Competence/standards , Curriculum/standards , Education, Nursing, Baccalaureate/methods , Education, Nursing, Baccalaureate/standards , England , Female , Humans , Maternal Health Services , Pregnancy , Qualitative Research , Surveys and Questionnaires , WorkforceABSTRACT
BACKGROUND: Radial dysplasia affects 1 in 6,000 to 8,000 births, classically presenting with a shortened, bowed ulna and radially deviated hand. The optimal treatment remains unclear, with several opposing approaches advocated. This review aims to clarify the long-term outcomes of nonsurgical and surgical treatment of the "wrist" deformity. METHODS: The Embase, MEDLINE, PubMed, Cochrane Central, ClinicalTrials.gov, and World Health Organization International Clinical Trials Registry Platform (ICTRP) databases were searched for published and unpublished studies reporting long-term outcomes of surgical or nonsurgical treatment of children with radial dysplasia. Results were not restricted by date or language. Primary outcomes were hand-forearm angle, ulnar length, and "wrist" active range of motion (ROM). Studies were assessed using the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) criteria. Data for the change in hand-forearm angle were pooled using random-effects meta-analysis, and mean differences and 95% confidence intervals were obtained. Primary outcome data at last follow-up were pooled, and means and standard deviations were obtained. The PROSPERO registration of this study was CRD42016036665. RESULTS: Of 104 studies identified, 12 were included in this review. Five were retrospective cohort studies and 7 were case series. No randomized studies were found. Study quality was low or very low according to the GRADE criteria. The hand-forearm angle of nonsurgically treated patients worsened during childhood, from 66° to 84°, whereas "wrist" active ROM, at 61°, was better than that for most surgically treated patients. Ulnar length with nonsurgical treatment was predicted to be 64% of normal, but was not directly reported. Isolated soft-tissue release provided a modest reduction in hand-forearm angle compared with nonsurgical treatment. Soft-tissue distraction with centralization or radialization achieved the best hand-forearm angle correction (16° radial deviation). Radialization maintained better "wrist" active ROM (46°) and ulnar length than centralization. Microvascular second metatarsophalangeal joint transfer yielded better reported "wrist" active ROM (83°) and good ulnar length compared with other surgical techniques, but a slightly worse hand-forearm angle (28°). CONCLUSIONS: There was low-quality evidence that soft-tissue distraction plus centralization or radialization achieved the best correction of the hand-forearm angle for children with radial dysplasia. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
Subject(s)
Hand Deformities, Congenital/diagnostic imaging , Hand Deformities, Congenital/surgery , Orthopedic Procedures/methods , Plastic Surgery Procedures/methods , Radius/abnormalities , Wrist Joint/abnormalities , Age Factors , Female , Humans , Male , Radius/diagnostic imaging , Recovery of Function , Risk Assessment , Treatment Outcome , Wrist Joint/diagnostic imagingABSTRACT
To more fully understand the molecular mechanisms responsible for variations in binding affinity with antibody maturation, we explored the use of site specific fluorine labeling and (19)F nuclear magnetic resonance (NMR). Several single-chain (scFv) antibodies, derived from an affinity-matured series of anti-hen egg white lysozyme (HEL) mouse IgG1, were constructed with either complete or individual replacement of tryptophan residues with 5-fluorotryptophan ((5F)W). An array of biophysical techniques was used to gain insight into the impact of fluorine substitution on the overall protein structure and antigen binding. SPR measurements indicated that (5F)W incorporation lowered binding affinity for the HEL antigen. The degree of analogue impact was residue-dependent, and the greatest decrease in affinity was observed when (5F)W was substituted for residues near the binding interface. In contrast, corresponding crystal structures in complex with HEL were essentially indistinguishable from the unsubstituted antibody. (19)F NMR analysis showed severe overlap of signals in the free fluorinated protein that was resolved upon binding to antigen, suggesting very distinct chemical environments for each (5F)W in the complex. Preliminary relaxation analysis suggested the presence of chemical exchange in the antibody-antigen complex that could not be observed by X-ray crystallography. These data demonstrate that fluorine NMR can be an extremely useful tool for discerning structural changes in scFv antibody-antigen complexes with altered function that may not be discernible by other biophysical techniques.
Subject(s)
Antibodies, Monoclonal/chemistry , Antigens/metabolism , Fluorine/metabolism , Muramidase/chemistry , Animals , Antibodies, Monoclonal/metabolism , Antigens/chemistry , Binding Sites, Antibody , Crystallography, X-Ray/methods , Immunoglobulin G/chemistry , Immunoglobulin G/metabolism , Isotope Labeling/methods , Mice , Molecular Dynamics Simulation , Muramidase/immunology , Muramidase/metabolism , Nuclear Magnetic Resonance, Biomolecular/methods , Protein Binding/immunology , Protein Structure, Secondary , Protein Structure, TertiaryABSTRACT
This article describes the findings from a pilot study undertaken to identify the potential benefits of a ward simulation exercise in developing the capabilities of newly qualified nurses. Eight newly qualified nurses were recruited to participate in this pilot study which was based in the Clinical Skills Centre, Ninewells Hospital, Dundee. This pilot study was performed in conjunction with NHS Tayside Practice Education Facilitators and the University of Dundee. Data collection methods involved reflective learning logs which were reviewed independently by an expert group of teachers and practitioners. A focus group session was also undertaken to understand the lived experience of the newly qualified nurse during the ward simulation exercise. Core themes (listed in order of importance) related to the professional development of newly qualified nurses that were identified through this pilot study were: an increase in confidence, development of stress management skills, improved management of the acutely unwell patient, the transfer of skills learnt in simulation to the clinical setting, development of communication skills and reflection skills. Participants in this pilot study demonstrated increased levels of confidence in their communication skills, their ability to prioritize care and to engage in collaborative teamworking.
Subject(s)
Competency-Based Education/methods , Education, Nursing, Baccalaureate/methods , Interprofessional Relations , Nursing, Team/methods , Educational Measurement/methods , Focus Groups , Humans , Nursing Education Research , Nursing Evaluation Research , Pilot ProjectsABSTRACT
BACKGROUND: Combination therapy with deferoxamine and oral deferiprone is superior to deferoxamine alone in removing cardiac iron and improving left ventricular ejection fraction (LVEF). The right ventricle (RV) is also affected by the toxic effects of iron and may cause additional cardiovascular perturbation. We assessed the effects of combination therapy on the RV in thalassaemia major (TM) using cardiovascular magnetic resonance (CMR). METHODS: We retrieved imaging data from 2 treatment trials and re-analyzed the data for the RV responses: Trial 1 was a randomized controlled trial (RCT) of 65 TM patients with mild-moderate cardiac siderosis receiving combination therapy or deferoxamine with placebo; Trial 2 was an open label longitudinal trial assessing combination therapy in 15 TM patients with severe iron loading. RESULTS: In the RCT, combination therapy with deferoxamine and deferiprone was superior to deferoxamine alone for improving RVEF (3.6 vs 0.7%, p = 0.02). The increase in RVEF was greater with lower baseline T2* 8-12 ms (4.7 vs 0.5%, p = 0.01) than with T2* 12-20 ms (2.2 vs 0.8%, p = 0.47). In patients with severe cardiac siderosis, substantial improvement in RVEF was seen with open-label combination therapy (10.5% ± 5.6%, p < 0.01). CONCLUSIONS: In the RCT of mild to moderate cardiac iron loading, combination treatment improved RV function significantly more than deferoxamine alone. Combination treatment also improved RV function in severe cardiac siderosis. Therefore adding deferiprone to deferoxamine has beneficial effects on both RV and LV function in TM patients with cardiac siderosis.
Subject(s)
Deferoxamine/therapeutic use , Hemosiderosis/drug therapy , Iron Chelating Agents/therapeutic use , Pyridones/therapeutic use , Siderophores/therapeutic use , Ventricular Dysfunction, Right/drug therapy , Ventricular Function, Right/drug effects , beta-Thalassemia/drug therapy , Adult , Analysis of Variance , Chi-Square Distribution , Deferiprone , Drug Therapy, Combination , Echocardiography, Doppler , Female , Hemosiderosis/diagnosis , Hemosiderosis/etiology , Hemosiderosis/physiopathology , Humans , Magnetic Resonance Imaging , Male , Randomized Controlled Trials as Topic , Recovery of Function , Retrospective Studies , Severity of Illness Index , Stroke Volume/drug effects , Therapeutics , Time Factors , Ventricular Dysfunction, Right/diagnosis , Ventricular Dysfunction, Right/etiology , Ventricular Dysfunction, Right/physiopathology , beta-Thalassemia/complications , beta-Thalassemia/diagnosis , beta-Thalassemia/physiopathologyABSTRACT
Congenital nail fold hypertrophy of the hallux is an uncommon abnormality affecting the periungual soft tissue of the great toe. It is usually identified at birth or shortly thereafter, and is known to spontaneously resolve in most cases. In this report, we describe the case of a 14-month-old boy presenting with nail fold hypertrophy of both great toes. The completely united skin bridge covering the nail on the right was excised and the nail folds recreated, with debulking of the left hypertrophic nail fold. We propose that management should be conservative in the first instance and that surgery should be reserved for cases in which 1) inflammation is unresponsive to conservative measures, 2) there is a dense condensation of tissue crossing the nail surface, or 3) there is significant hypertrophy persisting past 1 year of age with no signs of resolution.
Subject(s)
Hallux/surgery , Nails/pathology , Nails/surgery , Humans , Hypertrophy/congenital , Hypertrophy/surgery , Infant , MaleABSTRACT
We report the design of novel, potent cPLA(2)α inhibitors that possess an α-methyl-2-ketothiazole that acts as a serine-reactive moiety. We describe the optimization of the series for potency and metabolic stability towards ketone reduction. This was achieved by attenuating the reactivity of the ketone using a combination of electronic and steric effects.
Subject(s)
Drug Design , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Group IV Phospholipases A2/antagonists & inhibitors , Ketones/chemistry , Thiazoles/chemical synthesis , Thiazoles/pharmacology , Animals , Drug Stability , Enzyme Activation/drug effects , Enzyme Inhibitors/chemistry , HL-60 Cells , Humans , Inhibitory Concentration 50 , Ketones/chemical synthesis , Ketones/pharmacology , Magnetic Resonance Spectroscopy , Molecular Structure , Oxidation-Reduction , Rats , Serine/chemistry , Thiazoles/chemistryABSTRACT
AIMS: Myocardial T2* cardiovascular magnetic resonance (CMR) provides a rapid and reproducible measure of cardiac iron loading and is being increasingly used worldwide for monitoring of transfusion-dependent thalassaemia patients. Although myocardial siderosis (T2* <20 ms) is associated with impaired left ventricular (LV) function, little is known of its relation with right ventricular (RV) function. The aim of this study was to investigate the relationship between cardiac T2* and RV function. METHODS AND RESULTS: A retrospective analysis of 319 patients with beta-thalassaemia major presenting for their first CMR scan was performed (45.1% male, mean age 25.6 years). In patients with normal myocardial T2* (>20 ms), the RV ejection fraction (EF) was within the normal range in 98% of patients. When myocardial T2* was <20 ms, there was a progressive and significant decline in RV EF. There was a linear relationship between RV and LV EF. CONCLUSION: Myocardial iron deposition is strongly associated with RV dysfunction, which mirrors the decrease in LV function seen with worsening cardiac iron loading. Right ventricular dysfunction may play a significant role in heart failure associated with myocardial siderosis.
Subject(s)
Cardiomyopathies/diagnosis , Ventricular Dysfunction, Right/diagnosis , beta-Thalassemia/complications , Adult , Cardiomyopathies/physiopathology , Female , Heart Failure/etiology , Heart Ventricles , Hemosiderosis/complications , Hemosiderosis/physiopathology , Humans , Iron/metabolism , Magnetic Resonance Angiography , Male , Retrospective Studies , Stroke Volume , Ventricular Dysfunction, Right/physiopathology , beta-Thalassemia/physiopathologySubject(s)
B-Lymphocyte Subsets/immunology , Immunoglobulins/genetics , Self Tolerance/genetics , Self Tolerance/immunology , Animals , B-Lymphocyte Subsets/metabolism , B-Lymphocyte Subsets/pathology , Female , History, 20th Century , Immunoglobulins/metabolism , Male , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Inbred CBA , Mice, TransgenicABSTRACT
Thermodynamic and structural studies addressed the increased affinity due to L-chain somatic mutations in the HyHEL-10 family of affinity matured IgG antibodies, using ITC, SPR with van't Hoff analysis, and X-ray crystallography. When compared to the parental antibody H26L26, the H26L10 and H26L8 chimeras binding to lysozyme showed an increase in favorable DeltaG(o) of -1.2+/-0.1 kcal mol(-1) and -1.3+/-0.1 kcal mol(-1), respectively. Increase in affinity of the H26L10 chimera was due to a net increase in favorable enthalpy change with little difference in change in entropy compared to H26L26. The H26L8 chimera exhibited the greatest increase in favorable enthalpy but also showed an increase in unfavorable entropy change, with the result being that the affinities of both chimeras were essentially equivalent. Site-directed L-chain mutants identified the shared somatic mutation S30G as the dominant contributor to increasing affinity to lysozyme. This mutation was not influenced by H-chain somatic mutations. Residue 30L is at the periphery of the binding interface and S30G effects an increase in hydrophobicity and decrease in H-bonding ability and size, but does not make any new energetically important antigen contacts. A new 1.2-A structure of the H10L10-HEL complex showed changes in the pattern of both inter- and intra-molecular water bridging with no other significant structural alterations near the binding interface compared to the H26L26-HEL complex. These results highlight the necessity for investigating both the structure and the thermodynamics associated with introduced mutations, in order to better assess and understand their impact on binding. Furthermore, it provides an important example of how backbone flexibility and water-bridging may favorably influence the thermodynamics of an antibody-antigen interaction.
Subject(s)
Antibodies/chemistry , Antibodies/genetics , Immunoglobulin Light Chains/genetics , Mutation/genetics , Water/chemistry , Antibodies/immunology , Calorimetry , Crystallography, X-Ray , Glycine/chemistry , Immunoglobulin Fab Fragments/immunology , Immunoglobulin Heavy Chains/chemistry , Immunoglobulin Heavy Chains/genetics , Models, Molecular , Muramidase/chemistry , Muramidase/immunology , Pliability , Protein Structure, Secondary , ThermodynamicsABSTRACT
HyHEL-8, HyHEL-10, and HyHEL-26 (HH8, HH10, and HH26, respectively) are murine monoclonal IgG(1) antibodies which share over 90% variable-region amino acid sequence identity and recognize identical structurally characterized epitopes on hen egg white lysozyme (HEL). Previous immunochemical and surface plasmon resonance-based studies have shown that these antibodies differ widely in their tolerance of mutations in the epitope. While HH8 is the most cross-reactive, HH26 is rigidified by a more extensive network of intramolecular salt links and is highly specific, with both association and dissociation rates strongly affected by epitope mutations. HH10 is of intermediate specificity, and epitope mutations produce changes primarily in the dissociation rate. Calorimetric characterization of the association energetics of these three antibodies with the native antigen HEL and with Japanese quail egg white lysozyme (JQL), a naturally occurring avian variant, shows that the energetics of interaction correlate with cross-reactivity and specificity. These results suggest that the greater cross-reactivity of HH8 may be mediated by a combination of conformational flexibility and less specific intermolecular interactions. Thermodynamic calculations suggest that upon association HH8 incurs the largest configurational entropic penalty and also the smallest loss of enthalpic driving force with variant antigen. Much smaller structural perturbations are expected in the formation of the less flexible HH26 complex, and the large loss of enthalpic driving force observed with variant antigen reflects its specificity. The observed thermodynamic parameters correlate well with the observed functional behavior of the antibodies and illustrate fundamental differences in thermodynamic characteristics between cross-reactive and specific molecular recognition.