ABSTRACT
Gender variations in health literacy have implications for engagement in preventive behaviours and the uptake of health services, especially in areas such as the Caribbean where there are marked disparities in life expectancy and health service utilization. A self-reported questionnaire was used to examine men's concepts of health, their help-seeking behaviours and their functional and interactive health literacy. Two hundred and forty-eight men across the life course participated at three sites in Trinidad. Data were analysed using descriptive statistics, with free-text responses analysed thematically. Men were concerned about, and accepted responsibility for their own health but social norms concerning sickness and masculinity were barriers to accessing health services. Almost one-third (31.5%) sought advice from a healthcare service when they were last sick because they were prompted to do so by their wife/partner or family. Levels of functional and interactive health literacy were not high among older men, who were reliant on healthcare professionals to communicate health messages. There was an age divide in e-health literacy. There is little published evidence on men's health literacy, particularly from Caribbean countries such as Trinidad and Tobago. This study highlights the importance of the design and implementation of specific policies focusing on men's health. A major challenge is to engage with men who do not access health services.
Subject(s)
Health Knowledge, Attitudes, Practice , Health Literacy/statistics & numerical data , Men's Health , Adolescent , Adult , Aged , Health Services/statistics & numerical data , Humans , Male , Masculinity , Middle Aged , Surveys and Questionnaires , Telemedicine , Trinidad and TobagoABSTRACT
Background Rheumatoid arthritis is a chronic and common inflammatory autoimmune disease. This primarily involves the synovia of the joints, but can cause many extra-articular manifestations as well, including peripheral ulcerative keratitis (PUK) and necrotising scleritis. These are often a threat to vision; they significantly compromise not only the eye's structural integrity but are also important for prognosis and need urgent management. History and signs Three cases of peripheral ulcerative keratitis associated with rheumatoid arthritis were recorded in the electronic databank of the Jules Gonin Uveitis Clinic, two with necrotising scleritis and peripheral ulcerative keratitis and one with only peripheral ulcerative keratitis. They were all followed at Jules Gonin Eye Hospital (Lausanne, Switzerland), conjointly with the Department of Rheumatology at the Centre Hospitalier Universitaire Vaudois (Lausanne, Switzerland). Therapy and Outcome Good initial therapeutic response was observed in the two patients who received rituximab therapy. The patient who received only high dose corticosteroid developed massive colon perforation as well as acute renal insufficiency a few days after her ocular event. Conclusion From our limited number of patients, we found that the two patients who received the induction therapy with rituximab were stabilised from an ocular standpoint; however, rituximab had to be switched to other molecules, either due to other systemic symptoms from the disease itself or due to adverse effect of this treatment. This contributes to the increasing number of reports that rituximab can be an effective treatment for refractory ocular complications of rheumatoid arthritis (RA), at least as an induction therapy.
Subject(s)
Arthritis, Rheumatoid/diagnosis , Arthritis, Rheumatoid/drug therapy , Corneal Ulcer/diagnosis , Corneal Ulcer/drug therapy , Rituximab/administration & dosage , Scleritis/diagnosis , Scleritis/drug therapy , Aged , Aged, 80 and over , Antirheumatic Agents/administration & dosage , Arthritis, Rheumatoid/complications , Corneal Ulcer/complications , Diagnosis, Differential , Female , Humans , Immunosuppressive Agents/administration & dosage , Scleritis/complications , Treatment OutcomeABSTRACT
Anaphylaxis has been defined as a 'severe, life-threatening generalized or systemic hypersensitivity reaction'. However, data indicate that the vast majority of food-triggered anaphylactic reactions are not life-threatening. Nonetheless, severe life-threatening reactions do occur and are unpredictable. We discuss the concepts surrounding perceptions of severe, life-threatening allergic reactions to food by different stakeholders, with particular reference to the inclusion of clinical severity as a factor in allergy and allergen risk management. We review the evidence regarding factors that might be used to identify those at most risk of severe allergic reactions to food, and the consequences of misinformation in this regard. For example, a significant proportion of food-allergic children also have asthma, yet almost none will experience a fatal food-allergic reaction; asthma is not, in itself, a strong predictor for fatal anaphylaxis. The relationship between dose of allergen exposure and symptom severity is unclear. While dose appears to be a risk factor in at least a subgroup of patients, studies report that individuals with prior anaphylaxis do not have a lower eliciting dose than those reporting previous mild reactions. It is therefore important to consider severity and sensitivity as separate factors, as a highly sensitive individual will not necessarily experience severe symptoms during an allergic reaction. We identify the knowledge gaps that need to be addressed to improve our ability to better identify those most at risk of severe food-induced allergic reactions.
Subject(s)
Allergens/immunology , Anaphylaxis/diagnosis , Anaphylaxis/etiology , Food Hypersensitivity/diagnosis , Food/adverse effects , Anaphylaxis/epidemiology , Animals , Food Handling/legislation & jurisprudence , Food Handling/methods , Food Handling/standards , Food Hypersensitivity/epidemiology , Food-Processing Industry/legislation & jurisprudence , Food-Processing Industry/standards , Humans , Prognosis , Risk Assessment , Severity of Illness IndexABSTRACT
Hypertrophic osteoarthropathy is sometimes the paraneoplasic manifestation of cancer of pulmonary origin. It is rarely present in case of breast cancer, even at a metastatic stage. In its complete form, this entity includes periostitis (predominantly bilateral and affecting upper and lower limbs), digital clubbing and, rarely, arthritis. We report the case of a female patient with metastatic breast cancer and an incomplete form of hypertrophic osteoarthropathy, clearly asymetric and without digital clubbing.
Subject(s)
Bone Neoplasms/complications , Bone Neoplasms/secondary , Breast Neoplasms/pathology , Carcinoma, Ductal, Breast/complications , Carcinoma, Ductal, Breast/secondary , Osteoarthropathy, Secondary Hypertrophic/etiology , Aged , Female , HumansABSTRACT
BACKGROUND: BRAF V600E mutation has been reported to show a high specificity for papillary thyroid carcinoma (PTC). Using this marker to upgrade 'indeterminate' or 'suspicious' thyroid fine needle aspiration (FNA) cytology to 'malignant' could potentially allow one-stage therapeutic total thyroidectomy. METHODS: For a 14-month period, FNA cytology specimens in the Thy3-5 categories, which are the UK equivalents of indeterminate (Thy3a, atypical; Thy3f, follicular), suspicious for malignancy (Thy4) and malignant (Thy5) in the Bethesda System, underwent BRAF mutation testing by melt curve analysis. The results were correlated with histology. RESULTS: We tested 123 cytology specimens of which 12 (9.8%) failed. The BRAF mutation rate in the remainder was 16.2% (18/111), with 93 showing the wild-type. Seventeen mutations were V600E and one was non-V600E. The rate of mutation increased significantly (P < 0.0001 if Thy3a and Thy3f were combined) with the cytology category: 1/42 Thy3a (2.4%), 1/36 Thy3f (2.8%), 4/15 Thy4 (26.7%), 12/18 Thy5 (66.7%). All BRAF mutations correlated with PTC on histology, except for one recurrent PTC without histology. One mutation-positive case with Thy3a cytology showed the target lesion to be a 10-mm follicular adenoma on histology with an immediately adjacent 4-mm micro-PTC, in a patient who did not require total thyroidectomy. CONCLUSION: BRAF mutational analysis by melt curve analysis is feasible in routine thyroid cytology, and in our series had a 100% specificity for PTC in subsequent histology. The application of BRAF analysis could be useful for indeterminate cytology, but we suggest that it would be most appropriate and cost-effective for Thy4/suspicious cases, for which it could enable one-stage therapeutic surgery in the context of multidisciplinary discussion. In contrast, the sensitivity is low and there is no role for avoiding diagnostic thyroid surgery if wild-type BRAF is found.
Subject(s)
Biopsy, Fine-Needle , Carcinoma/genetics , Proto-Oncogene Proteins B-raf/genetics , Thyroid Gland/pathology , Thyroid Neoplasms/genetics , Carcinoma/pathology , Carcinoma, Papillary , DNA Mutational Analysis , Humans , Mutation , Neoplasm Staging , Nucleic Acid Denaturation/genetics , Thyroid Cancer, Papillary , Thyroid Neoplasms/pathology , Thyroid Nodule/genetics , Thyroid Nodule/pathologyABSTRACT
Increases in the demand and price for industrial metals, combined with advances in technological capabilities have now made deep-sea mining more feasible and economically viable. In order to balance economic interests with the conservation of abyssal plain ecosystems, it is becoming increasingly important to develop a systematic approach to spatial management and zoning of the deep sea. Here, we describe an expert-driven systematic conservation planning process applied to inform science-based recommendations to the International Seabed Authority for a system of deep-sea marine protected areas (MPAs) to safeguard biodiversity and ecosystem function in an abyssal Pacific region targeted for nodule mining (e.g. the Clarion-Clipperton fracture zone, CCZ). Our use of geospatial analysis and expert opinion in forming the recommendations allowed us to stratify the proposed network by biophysical gradients, maximize the number of biologically unique seamounts within each subregion, and minimize socioeconomic impacts. The resulting proposal for an MPA network (nine replicate 400 × 400 km MPAs) covers 24% (1 440 000 km(2)) of the total CCZ planning region and serves as example of swift and pre-emptive conservation planning across an unprecedented area in the deep sea. As pressure from resource extraction increases in the future, the scientific guiding principles outlined in this research can serve as a basis for collaborative international approaches to ocean management.
Subject(s)
Conservation of Natural Resources , Mining , Biodiversity , Oceans and SeasABSTRACT
We observed, for the first time, solar neutrinos in the 1.0-1.5 MeV energy range. We determined the rate of pep solar neutrino interactions in Borexino to be 3.1±0.6{stat}±0.3{syst} counts/(day·100 ton). Assuming the pep neutrino flux predicted by the standard solar model, we obtained a constraint on the CNO solar neutrino interaction rate of <7.9 counts/(day·100 ton) (95% C.L.). The absence of the solar neutrino signal is disfavored at 99.97% C.L., while the absence of the pep signal is disfavored at 98% C.L. The necessary sensitivity was achieved by adopting data analysis techniques for the rejection of cosmogenic {11}C, the dominant background in the 1-2 MeV region. Assuming the Mikheyev-Smirnov-Wolfenstein large mixing angle solution to solar neutrino oscillations, these values correspond to solar neutrino fluxes of (1.6±0.3)×10{8} cm{-2} s^{-1} and <7.7×10{8} cm{-2} s{-1} (95% C.L.), respectively, in agreement with both the high and low metallicity standard solar models. These results represent the first direct evidence of the pep neutrino signal and the strongest constraint of the CNO solar neutrino flux to date.
ABSTRACT
BACKGROUND: Although patients with Alzheimer's disease and other cognitive-related neurodegenerative disorders may benefit from early detection, development of a reliable diagnostic test has remained elusive. The penetration of digital voice-recording technologies and multiple cognitive processes deployed when constructing spoken responses might offer an opportunity to predict cognitive status. OBJECTIVE: To determine whether cognitive status might be predicted from voice recordings of neuropsychological testing. DESIGN: Comparison of acoustic and (para)linguistic variables from low-quality automated transcriptions of neuropsychological testing (n = 200) versus variables from high-quality manual transcriptions (n = 127). We trained a logistic regression classifier to predict cognitive status, which was tested against actual diagnoses. SETTING: Observational cohort study. PARTICIPANTS: 146 participants in the Framingham Heart Study. MEASUREMENTS: Acoustic and either paralinguistic variables (e.g., speaking time) from automated transcriptions or linguistic variables (e.g., phrase complexity) from manual transcriptions. RESULTS: Models based on demographic features alone were not robust (area under the receiver-operator characteristic curve [AUROC] 0.60). Addition of clinical and standard acoustic features boosted the AUROC to 0.81. Additional inclusion of transcription-related features yielded an AUROC of 0.90. CONCLUSIONS: The use of voice-based digital biomarkers derived from automated processing methods, combined with standard patient screening, might constitute a scalable way to enable early detection of dementia.
Subject(s)
Cognitive Dysfunction , Humans , Cognitive Dysfunction/diagnosis , Language , Sensitivity and Specificity , Biomarkers , CognitionABSTRACT
Heterostructures are central to the efficient manipulation of charge carriers, excitons and photons for high-performance semiconductor devices. Although these can be formed by stepwise evaporation of molecular semiconductors, they are a considerable challenge for polymers owing to re-dissolution of the underlying layers. Here we demonstrate a simple and versatile photocrosslinking methodology based on sterically hindered bis(fluorophenyl azide)s. The photocrosslinking efficiency is high and dominated by alkyl side-chain insertion reactions, which do not degrade semiconductor properties. We demonstrate two new back-infiltrated and contiguous interpenetrating donor-acceptor heterostructures for photovoltaic applications that inherently overcome internal recombination losses by ensuring path continuity to give high carrier-collection efficiency. This provides the appropriate morphology for high-efficiency polymer-based photovoltaics. We also demonstrate photopatternable polymer-based field-effect transistors and light-emitting diodes, and highly efficient separate-confinement-heterostructure light-emitting diodes. These results open the way to the general development of high-performance polymer semiconductor heterostructures that have not previously been thought possible.
ABSTRACT
The rate of neutrino-electron elastic scattering interactions from 862 keV (7)Be solar neutrinos in Borexino is determined to be 46.0±1.5(stat)(-1.6)(+1.5)(syst) counts/(day·100 ton). This corresponds to a ν(e)-equivalent (7)Be solar neutrino flux of (3.10±0.15)×10(9) cm(-2) s(-1) and, under the assumption of ν(e) transition to other active neutrino flavours, yields an electron neutrino survival probability of 0.51±0.07 at 862 keV. The no flavor change hypothesis is ruled out at 5.0 σ. A global solar neutrino analysis with free fluxes determines Φ(pp)=6.06(-0.06)(+0.02)×10(10) cm(-2) s(-1) and Φ(CNO)<1.3×10(9) cm(-2) s(-1) (95% C.L.). These results significantly improve the precision with which the Mikheyev-Smirnov-Wolfenstein large mixing angle neutrino oscillation model is experimentally tested at low energy.
ABSTRACT
BACKGROUND: Antipsychotics are perceived to be over-used in the management of behavioural problems in people with an intellectual disability (ID). Published guidelines have set good practice standards for the use of these drugs for behavioural indications. We sought to identify the range of indications for which antipsychotic drugs are prescribed in people with ID and to audit clinical practice against the standards. METHOD: Data were collected from the clinical records of individuals with ID who were under the care of mental health services in the UK, and prescribed an antipsychotic drug. RESULTS: The sample comprised 2319 patients from 39 clinical services. Twenty-seven per cent of the patients had a diagnosis of a psychotic illness (ICD-10 F20-29) and 27% an affective illness (ICD-10 F30-39). The proportion who did not have a psychiatric diagnosis ranged from 6% of those with borderline/mild ID to 21% of those with severe/profound ID. Overall, the most common indications for prescribing an antipsychotic drug were comorbid psychotic illness, anxiety and agitation, and a range of behavioural disturbances. The prevalence of use of antipsychotic drugs to manage challenging behaviour in the absence of concomitant mental illness increased with the severity of ID and accounted for almost half of prescriptions in those with severe/profound ID. Adherence to the audit standards related to documentation of clinical indications and review of efficacy was high. Side effect monitoring was less assiduous. CONCLUSIONS: In clinical practice, most prescriptions for antipsychotic drugs in people with ID are consistent with the evidence base and the overall quality of prescribing practice, as measured against recognised standards, is good, although in some patients potentially remedial side effects may not be detected and treated.
Subject(s)
Antipsychotic Agents/therapeutic use , Attention Deficit and Disruptive Behavior Disorders/drug therapy , Intellectual Disability/drug therapy , Mental Disorders/drug therapy , Mental Health Services/statistics & numerical data , Adolescent , Adult , Aged , Attention Deficit and Disruptive Behavior Disorders/epidemiology , Comorbidity , Evidence-Based Medicine/standards , Evidence-Based Medicine/statistics & numerical data , Female , Humans , Intellectual Disability/epidemiology , Male , Mental Disorders/epidemiology , Mental Health Services/standards , Middle Aged , Practice Patterns, Physicians'/standards , Practice Patterns, Physicians'/statistics & numerical data , United Kingdom/epidemiology , Young AdultABSTRACT
Mitosis in human cells is initiated by the protein kinase Cdc2-cyclin B1, which is activated at the end of G2 by dephosphorylation of two inhibitory residues, Thr14 and Tyr15. The G2 arrest that occurs after DNA damage is due in part to stabilization of phosphorylation at these sites. We explored the possibility that entry into mitosis is also regulated by the subcellular location of Cdc2-cyclin B1, which is suddenly imported into the nucleus at the end of G2. We measured the timing of mitosis in HeLa cells expressing a constitutively nuclear cyclin B1 mutant. Parallel studies were performed with cells expressing Cdc2AF, a Cdc2 mutant that cannot be phosphorylated at inhibitory sites. Whereas nuclear cyclin B1 and Cdc2AF each had little effect under normal growth conditions, together they induced a striking premature mitotic phenotype. Nuclear targeting of cyclin B1 was particularly effective in cells arrested in G2 by DNA damage, where it greatly reduced the damage-induced G2 arrest. Expression of nuclear cyclin B1 and Cdc2AF also resulted in significant defects in the exit from mitosis. Thus, nuclear targeting of cyclin B1 and dephosphorylation of Cdc2 both contribute to the control of mitotic entry and exit in human cells.
Subject(s)
CDC2 Protein Kinase/metabolism , Cell Cycle/physiology , Cell Nucleus/metabolism , Cyclin B/metabolism , DNA Damage , Mitosis/physiology , Adenoviridae , Amino Acid Sequence , CDC2 Protein Kinase/biosynthesis , Cyclin B/biosynthesis , Cyclin B1 , Epitopes , G1 Phase , G2 Phase , HeLa Cells , Humans , Kinetics , Phosphorylation , Proto-Oncogene Proteins c-myc/biosynthesis , Recombinant Fusion Proteins/biosynthesis , Recombinant Fusion Proteins/metabolism , S Phase , Time Factors , TransfectionABSTRACT
The first step of assembly of the nicotinic acetylcholine receptor (AChR) of adult skeletal muscle is the specific association of the alpha subunit with either delta or epsilon subunits to form a heterodimer with a ligand-binding site. Previous experiments have suggested that het erodimer formation in the ER arises from interaction between the luminal, NH2-terminal domains of the subunits. When expressed in COS cells with the delta subunit, however, the truncated NH2-terminal domain of the subunit folded correctly but did not form a heterodimer. Association with the delta subunit occurred only when the NH2-terminal domain was retained in the ER and was tethered to the membrane by its own M1 transmembrane domain, by the transmembrane domain of another protein, or by a glycolipid link. In each case, the ligand-binding sites of the resulting heterodimers were indistinguishable from that formed when the full-length alpha subunit was used. Attachment to the membrane may promote interaction by concentrating or orienting the subunit; alternatively, a membrane-bound factor may facilitate subunit association.
Subject(s)
Intracellular Membranes/metabolism , Receptors, Nicotinic/chemistry , Amino Acid Sequence , Animals , Binding Sites , Brefeldin A , Bungarotoxins/metabolism , COS Cells , Cyclopentanes/pharmacology , Dimerization , Endoplasmic Reticulum/chemistry , Glycosylphosphatidylinositols/analysis , Ligands , Mice , Molecular Sequence Data , Peptide Fragments/chemistry , Peptide Fragments/metabolism , Protein Conformation , Protein Folding , Protein Synthesis Inhibitors/pharmacology , Receptors, Nicotinic/metabolismABSTRACT
We report that the small GTPase, ADP-ribosylation factor 6 (ARF6), is present only on the apical surface of polarized MDCK epithelial cells. Overexpression of a mutant of ARF6, ARF6-Q67L, which is predicted to be in the GTP-bound form, stimulates endocytosis exclusively at this surface. Surprisingly, overexpression of the mutant ARF6-T27N, which is predicted to be in the GDP-bound form, also stimulated apical endocytosis, though to a lesser extent. ARF6-stimulated endocytosis is inhibited by a dominant-negative form of dynamin, or a dominant-negative hub fragment of clathrin heavy chain, indicating that it is mediated by clathrin. Correspondingly, overexpression of either mutant of ARF6 leads to an increase in the number of clathrin-coated pits at the apical plasma membrane. When ARF6-Q67L is overexpressed in the presence of the dominant-negative dynamin, the ARF6-Q67L colocalizes with clathrin and with IgA bound to its receptor. We conclude that ARF6 is an important modulator of clathrin-mediated endocytosis at the apical surface of epithelial cells.
Subject(s)
ADP-Ribosylation Factors/metabolism , Cell Polarity , Clathrin/metabolism , Endocytosis , Epithelial Cells/cytology , ADP-Ribosylation Factor 6 , ADP-Ribosylation Factors/genetics , Animals , Cell Line , Clathrin/genetics , Clathrin Heavy Chains , Coated Pits, Cell-Membrane/metabolism , Coated Pits, Cell-Membrane/ultrastructure , Dogs , Dynamins , Epithelial Cells/metabolism , Epithelial Cells/ultrastructure , GTP Phosphohydrolases/genetics , GTP Phosphohydrolases/metabolism , Genes, Dominant/genetics , Guanosine Diphosphate/metabolism , Guanosine Triphosphate/metabolism , Immunoglobulin A/immunology , Kidney , Microscopy, Electron , Mutation , Peptide Fragments/genetics , Peptide Fragments/metabolism , Recombinant Proteins/genetics , Recombinant Proteins/metabolismABSTRACT
A role for dynamin in clathrin-mediated endocytosis is now well established. However, mammals express three closely related, tissue-specific dynamin isoforms, each with multiple splice variants. Thus, an important question is whether these isoforms and splice variants function in vesicle formation from distinct intracellular organelles. There are conflicting data as to a role for dynamin-2 in vesicle budding from the TGN. To resolve this issue, we compared the effects of overexpression of dominant-negative mutants of dynamin-1 (the neuronal isoform) and dynamin-2 (the ubiquitously expressed isoform) on endocytic and biosynthetic membrane trafficking in HeLa cells and polarized MDCK cells. Both dyn1(K44A) and dyn2(K44A) were potent inhibitors of receptor-mediated endocytosis; however neither mutant directly affected other membrane trafficking events, including transport mediated by four distinct classes of vesicles budding from the TGN. Dyn2(K44A) more potently inhibited receptor-mediated endocytosis than dyn1(K44A) in HeLa cells and at the basolateral surface of MDCK cells. In contrast, dyn1(K44A) more potently inhibited endocytosis at the apical surface of MDCK cells. The two dynamin isoforms have redundant functions in endocytic vesicle formation, but can be targeted to and function differentially at subdomains of the plasma membrane.
Subject(s)
Endocytosis/physiology , GTP Phosphohydrolases/physiology , Protein Isoforms/physiology , Adenoviridae/genetics , Animals , Biological Transport , Cell Line , Cell Polarity , Dogs , Dynamin I , Dynamins , GTP Phosphohydrolases/genetics , Gene Expression Regulation/drug effects , Genetic Vectors , HeLa Cells , Humans , Kidney , Microscopy, Fluorescence , Protein Isoforms/genetics , Recombinant Fusion Proteins/metabolism , Tetracycline/pharmacologyABSTRACT
Passage of proteins across membranes during export from their site of synthesis to their final destination is mediated by leader peptides that paradoxically exhibit a unity of function in spite of a diversity of sequence. These leader peptides act in at least two stages of the export process: at entry into the pathway and subsequently during translocation across the membrane. How selectivity is imposed on the system in the absence of a consensus among the sequences of leader peptides is the main issue discussed here.
Subject(s)
Cell Membrane/metabolism , Models, Biological , Protein Sorting Signals/physiology , Proteins/metabolism , Amino Acid Sequence , Biological Transport , Escherichia coli/metabolism , Protein Conformation , Protein Precursors/metabolism , Structure-Activity RelationshipABSTRACT
An in vitro assay for the interaction of SecB, a molecular chaperone from Escherichia coli, with polypeptide ligands was established based on the ability of SecB to block the refolding of denatured maltose-binding protein. Competition experiments show that SecB binds selectively to nonnative proteins with high affinity and without specificity for a particular sequence of amino acids. It is proposed that selectivity in binding is due to a kinetic partitioning of polypeptides between folding and association with SecB.
Subject(s)
ATP-Binding Cassette Transporters , Bacterial Proteins/metabolism , Carrier Proteins/metabolism , Escherichia coli Proteins , Escherichia coli , Monosaccharide Transport Proteins , Amino Acid Sequence , Binding, Competitive , Kinetics , Ligands , Maltose/metabolism , Maltose-Binding Proteins , Protein ConformationABSTRACT
Most proteins destined for export from Escherichia coli are made as precursors containing amino-terminal leader sequences that are essential for export and that are removed during the process. The initial step in export of a subset of proteins, which includes maltose-binding protein, is binding of the precursor by the molecular chaperone SecB. This work shows directly that SecB binds with high affinity to unfolded maltose-binding protein but does not specifically recognize and bind the leader. Rather, the leader modulates folding to expose elements in the remainder of the polypeptide that are recognized by SecB.