Amyloidogenicity and aggregate cytotoxicity of human glucagon-like peptide-1 (hGLP-1).

The potential of human glucagon-like peptide-1 (hGLP-1) as a therapeutic agent is limited by its high aggregation propensity. We show that hGLP-1 forms amyloid-like structures that are preceded by cytotoxic aggregates, suggesting that aggregation of biopharmaceuticals could present a cytotoxic risk to patients besides the reported increased risk in immunogenicity.

Mapping the folding pathway of an immunoglobulin domain: structural detail from Phi value analysis and movement of the transition state.

BACKGROUND: Do proteins that have the same structure fold by the same pathway even when they are unrelated in sequence? To address this question, we are comparing the folding of a number of different immunoglobulin-like proteins. Here, we present a detailed protein engineering phi value analysis of the folding pathway of TI I27, an immunoglobulin domain from human cardiac titin. RESULTS: TI I27 folds rapidly via a kinetic intermediate that is destabilized by most mutations. The transition state for folding is remarkably native-like in terms of solvent accessibility. We use phi value analysis to map this transition state and show that it is highly structured; only a few residues close to the N-terminal region of the protein remain completely unfolded. Interestingly, most mutations cause the transition state to become less native-like. This anti-Hammond behavior can be used as a novel means of obtaining additional structural information about the transition state. CONCLUSIONS: The residues that are involved in nucleating the folding of TI I27 are structurally equivalent to the residues that form the folding nucleus in an evolutionary unrelated fibronectin type III protein. These residues form part of the common structural core of Ig-like domains. The data support the hypothesis that interactions essential for defining the structure of these beta sandwich proteins are also important in nucleation of folding.

The folding nucleus of a fibronectin type III domain is composed of core residues of the immunoglobulin-like fold.

To identify the contacts that stabilise the rate-limiting transition state for folding of FNfn10 (the tenth fnIII domain of human fibronectin), 42 mutants have been analysed at 29 positions across this domain. An anomalous response to mutation means that structure formation in the A, B and G strands cannot be evaluated by this method. In all the residues analysed, phi-values are fractional and no completely structured region is observed. The analysis reveals that hydrophobic residues from the central strands of the beta-sandwich form a large core of interactions in the transition state. Brønsted analysis shows that the stabilisation energy from the amino acid side-chains in the transition state is approximately 40 % of that in the native state. The protein folds by a nucleation-condensation mechanism, and tertiary interactions within the core make up the folding nucleus. Local interactions, in turns and loops, are apparently much less significant. Comparison with an homologous domain from human tenascin (TNfn3), shows that FNfn10 has a more extended, structured transition state spanning three different "layers" of the beta-sandwich. The results support the hypothesis that interactions in the common structural core guide the folding of these domains.

Two proteins with the same structure respond very differently to mutation: the role of plasticity in protein stability.

As part of a systematic study of the folding of protein structural families we compare the effect of mutation in two closely related fibronectin type III (fnIII) domains, the tenth fnIII domain of human fibronectin (FNfn10) and the third fnIII domain of human tenascin (TNfn3). This comparison of the two related proteins allows us to distinguish any anomalous response to mutation. Although they have very similar structures, the effect of mutation is very different. TNfn3 behaves like a "typical" protein, with changes in free energy correlated to the number of contacts lost on mutation. The loss of free energy upon mutation is significantly lower for FNfn10, particularly mutations of residues in the A, B and G strands. Remarkably, some of the residues involved are completely buried and closely packed in the core. In FNfn10 the regions of the protein that can accommodate mutation have previously been shown to be mobile. We propose that there is a "plasticity" in the peripheral regions of FNfn10 that allows it to rearrange to minimise the effect of mutations. This study emphasises the difficulties that might arise when making generalisations from a single member of a protein family.

Atomic force microscopy reveals the mechanical design of a modular protein.

Tandem modular proteins underlie the elasticity of natural adhesives, cell adhesion proteins, and muscle proteins. The fundamental unit of elastic proteins is their individually folded modules. Here, we use protein engineering to construct multimodular proteins composed of Ig modules of different mechanical strength. We examine the mechanical properties of the resulting tandem modular proteins by using single protein atomic force microscopy. We show that by combining modules of known mechanical strength, we can generate proteins with novel elastic properties. Our experiments reveal the simple mechanical design of modular proteins and open the way for the engineering of elastic proteins with defined mechanical properties, which can be used in tissue and fiber engineering.

Folding studies of immunoglobulin-like beta-sandwich proteins suggest that they share a common folding pathway.

BACKGROUND: Are folding pathways conserved in protein families? To test this explicitly and ask to what extent structure specifies folding pathways requires comparison of proteins with a common fold. Our strategy is to choose members of a highly diverse protein family with no conservation of function and little or no sequence identity, but with structures that are essentially the same. The immunoglobulin-like fold is one of the most common structural families, and is subdivided into superfamilies with no detectable evolutionary or functional relationship. RESULTS: We compared the folding of a number of immunoglobulin-like proteins that have a common structural core and found a strong correlation between folding rate and stability. The results suggest that the folding pathways of these immunoglobulin-like proteins share common features. CONCLUSIONS: This study is the first to compare the folding of structurally related proteins that are members of different superfamilies. The most likely explanation for the results is that interactions that are important in defining the structure of immunoglobulin-like proteins are also used to guide folding.

Patient care following carotid endarterectomy.

Individuals with carotid artery disease often enter the health care system for surgery. Since carotid endarterectomy is a surgical procedure with associated risks, it is essential for health care providers to understand operative interventions and cardiac and neurologic responses to provide competent postoperative care.

Mechanical and chemical unfolding of a single protein: a comparison.

Is the mechanical unraveling of protein domains by atomic force microscopy (AFM) just a technological feat or a true measurement of their unfolding? By engineering a protein made of tandem repeats of identical Ig modules, we were able to get explicit AFM data on the unfolding rate of a single protein domain that can be accurately extrapolated to zero force. We compare this with chemical unfolding rates for untethered modules extrapolated to 0 M denaturant. The unfolding rates obtained by the two methods are the same. Furthermore, the transition state for unfolding appears at the same position on the folding pathway when assessed by either method. These results indicate that mechanical unfolding of a single protein by AFM does indeed reflect the same event that is observed in traditional unfolding experiments. The way is now open for the extensive use of AFM to measure folding reactions at the single-molecule level. Single-molecule AFM recordings have the added advantage that they define the reaction coordinate and expose rare unfolding events that cannot be observed in the absence of chemical denaturants.

Impaired verbal communication during short-term oral intubation.

PURPOSE: To describe the experience of impaired verbal communication during short-term oral intubation in surgical critical care patients. METHODS: Semi-structured interviews (N = 10) FINDINGS: Patients identified feelings related to discomfort, fear, and frustration. Patients desired to communicate messages regarding pain and discomfort, difficulty breathing, length of intubation, use of restraints, family, physical status, and suctioning. CONCLUSION: Findings can be used to educate patients and families and develop patient-driven communication tools.

Neurotrauma family interventions.

TOPIC: Family responses to neurotrauma PURPOSE: To highlight the role of trauma nurses in providing education and support to families of neurotrauma patients SOURCES: Published literature and clinical experience CONCLUSIONS: Family-centered care can provide many positive outcomes: e.g., reduced stress, decreased anxiety, decreased powerlessness, increased understanding and support. The success of the patient's rehabilitation often depends on the care and involvement of their families.

Hope and a health-promoting lifestyle in persons with Parkinson's disease.

The purpose of this study was to determine relationships between hope and a health-promoting lifestyle in adults with varying stages of Parkinson's disease (PD) using a descriptive, correlational design. The sample of 42 adults, recruited from a PD educational symposium and support groups, completed the Herth Hope Index (HHI) and Health-Promoting Lifestyle Profile II (HPLP II). Significant correlations were found between hope and a total health-promoting lifestyle and spiritual growth and interpersonal relations subscales. Highest subscale means were in interpersonal relations and nutrition and the lowest mean was in physical activity. Despite a chronic, progressive neurological disease, adults in this study perceived themselves as hopeful and engaged in a health promoting lifestyle.

Health promotion in chronically ill older adults.

As the average life expectancy increases, older adults will be living longer with chronic illnesses. Health promotion is a multidimensional concept that applies to all individuals regardless of age of disability. As the needs of healthcare consumers change, neuroscience nurses are challenged to redefine health, aging, disability and health promotion. Strategies are needed to expand the knowledge base of health promotion including research, partnerships and communication.

Challenges in patient and family care following an unsuccessful suicide attempt.

According to the dictionary, challenge is a stimulating or interesting task or problem. But neuroscience nurses can offer a more comprehensive definition, especially in the context of caring for a patient and their family after an unsuccessful suicide attempt. This situation stimulates our thinking about why individuals try to take their lives, how suicide is attempted and what we, as nurses, can do to turn a hopeless situation into one of hope.

Collaborative efforts in achieving patient outcomes in central cord injury syndrome in the acute care setting.

Central cord injury results in motor impairment that is more prominent in the upper extremities than lower extremities with greater distal than proximal weakness. This altered health status directly impacts an individual's self care abilities. The combined focus of nursing care and occupational therapy delivered in a collaborative approach facilitates progress toward independence. An individual who has experienced central cord damage may be able to walk but not be able to eat, toilet, or dress without assistance. Most basic needs cannot be met independently without use of the arms. This type of injury has major implications for self care abilities.

Hope: implications for neuroscience nursing.

Hope is a response of patients and families to actual and potential health problems. The study of this phenomenon in neuroscience populations is limited. Facilitating hope in the health care setting results from an understanding of its definition and significance to nursing, multidisciplinary origins and scientific investigations. Nursing interventions should include attention to the environment, goals, relationships, change and energy.

Deep vein thrombosis and pulmonary emboli in neuroscience patients.

Patients with neurologic dysfunction, particularly spinal cord-injured and stroke patients, are at risk for developing thromboembolic complications due to a variety of factors, especially impaired mobility. Venous stasis, altered coagulability and endothelial vessel damage create a triad of pathophysiological changes that place patients at risk for developing deep vein thrombosis. Prophylactic use of pneumatic compression boots is highly recommended while administration of anticoagulants remains controversial and varied. Inferior vena cava filters are placed in patients who are high risk for pulmonary emboli. Nursing interventions focus on assessments of risk potential and clinical signs and symptoms and implementation of prevention strategies.

Pharmacological interventions for agitation in head-injured patients in the acute care setting.

Agitation following head injury challenges nurses to provide patient safety and participation in daily care and therapies. Diagnosis of the underlying disorder which causes agitative behavior is essential for rapid and successful treatment. A combination of pharmacological and nonpharmacological interventions are required to achieve this expected outcome. Propofol, lorazepam, midazolam and haloperidol are medications most commonly utilized in this patient care situation. The patient's sedation level should be monitored to avoid oversedation which may interfere with respiration and neurological status. Nurses need to understand the actions and adverse effects of these agents in order to advocate their proper usage in the agitated head-injured population.

Continuous duodenal infusions of levodopa.

Infusion of carbidopa/levodopa or levodopa through a duodenal tube can facilitate increased mobility and functional ability in individuals with Parkinson's disease when conventional drug therapy is unsuccessful in achieving desired outcomes. Therapy requires appropriate patient selection, ongoing assessment of the patient's physical and emotional needs and collaboration between the patient, nurses and physicians. Determining the amount of medication required to achieve the desired outcomes takes time. Implantable pumps may be a future strategy. Future research should focus on patient and family coping throughout hospitalization and at home so the emotional needs of this specific population can be met.

Nasopharyngeal angiofibroma: a case study.

Juvenile angiofibromas, most commonly found in adolescent males, are vascular lesions that occur in the nasopharynx and extend into other areas of the skull. Presenting signs and symptoms include epistaxis, nasal obstruction and nasal drainage. Computed tomography and magnetic resonance imaging are the primary diagnostic tests. Angiography is used for vascular mapping and preoperative embolization. Total surgical resection is the goal of treatment. Nursing care includes developmental considerations with a focus on comfort, neurological assessment and patient and family education.