Specific Interaction Sites Determine Differential Adsorption of Protein Structural Isomers on Nanoparticle Surfaces.

In biological systems, nanoparticles (NPs) elicit bioactivity upon interaction with proteins. As a result of post-translational modification, proteins occur in a variety of alternative covalent forms, including structural isomers, which present unique molecular surfaces. We aimed at a detailed description of the recognition of protein isomeric species by NP surfaces. The transient adsorption of isomeric ubiquitin (Ub) dimers by NPs was investigated by solution NMR spectroscopy. Lys63- and Lys48-linked Ub2 were adsorbed by large anionic NPs with different affinities, whereas the binding strength was similar in the cases of smaller particles. After the incorporation of paramagnetic tags into NPs, the observed site-resolved paramagnetic footprints provided a high-resolution map of the different protein surfaces binding to NPs. The approach described could be extended to further protein isoforms and more specialized NP systems to allow better control of the interactions between NPs and protein targets.

Alzheimer's disease-associated ubiquitin mutant Ubb+1: Properties of the carboxy-terminal domain and its influence on biomolecular interactions.

Ubb+1, a ubiquitin (Ub) mutant protein originating from misreading of the Ub B gene, is found accumulated in brain tissues of Alzheimer's disease patients. The mutant attracts strong interest due to its possible participation in the molecular events leading to neurodegeneration. Ubb+1 is composed of the globular domain of Ub, linked to a 19-residue C-terminal peptide. Based on NMR relaxation and solvent accessibility measurements we obtained new insight into the molecular properties of Ubb+1. We further determined the thermal stability of Ubb+1 in the monomeric form, and in Lys48- and Lys63-linked dimers. Finally, we explored the influence of the C-terminal fragment on the interactions of Ubb+1 with an isolated UBA2 domain and with membrane mimics. Our data indicate that the C-terminal fragment of Ubb+1 is overall highly flexible, except for a short stretch which appears less solvent-exposed. While influencing the hydrodynamic properties of the globular domain, the fragment does not establish long-lived interactions with the globular domain. It results that the structure and stability of Ub are minimally perturbed by the peptide extension. However, binding to UBA2 and to membrane mimics are both affected, exemplifying possible changes in biomolecular recognition experienced by the disease-associated Ubb+1 compared to the wild-type protein.

Molecular differences between human liver fatty acid binding protein and its T94A variant in their unbound and lipid-bound states.

Liver fatty acid binding protein (L-FABP) is an abundant cytosolic protein playing a central role in intracellular lipid trafficking. The L-FABP T94A variant, originating from one of the most common polymorphisms in the FABP family, is associated with several lipid-related disorders. However, the molecular factors that determine the observed functional differences are currently unknown. In our work, we performed a high resolution comparative molecular analysis of L-FABP T94T and L-FABP T94A in their unbound states and in the presence of representative ligands of the fatty acid and bile acid classes. We collected residue-resolved NMR spectral fingerprints of the two variants, and compared secondary structures, backbone dynamics, side chain arrangements, binding site occupation, and intermolecular contacts. We found that threonine to alanine replacement did not result in strongly perturbed structural and dynamic features, although differences in oleic acid binding by the two variants were detected. Based on chemical shift perturbations at sites distant from position 94 and on differences in intermolecular contacts, we suggest that long-range communication networks in L-FABP propagate the effect of amino acid substitution at sites relevant for ligand binding or biomolecular recognition.

Identification of primary and secondary UBA footprints on the surface of ubiquitin in cell-mimicking crowded solution.

Despite significant advancements in our understanding of ubiquitin-mediated signaling, the influence of the intracellular environment on the formation of transient ubiquitin-partner complexes remains poorly explored. In our work, we introduce macromolecular crowding as a first level of complexity toward the imitation of a cellular environment in the study of such interactions. Using NMR spectroscopy, we find that the stereospecific complex of ubiquitin and the ubiquitin-associated domain (UBA) is minimally perturbed by the crowding agent Ficoll. However, in addition to the primary canonical recognition patch on ubiquitin, secondary patches are identified, indicating that in cell-mimicking crowded solution, UBA contacts ubiquitin at multiple sites.

Intralipid in acute caffeine intoxication: a case report.

Caffeine is arguably the most widely used stimulant drug in the world. Here we describe a suicide attempt involving caffeine overdose whereby the patient's severe intoxication was successfully treated with the prompt infusion of Intralipid. A 19-year-old man was found in an agitated state at home by the volunteer emergency team about 1 h after the intentional ingestion of 40 g of caffeine (tablets). His consciousness decreased rapidly, followed quickly by seizures, and electrocardiographic monitoring showed ventricular fibrillation. Advanced life support maneuvers were started immediately, with the patient defibrillated 10 times and administered 5 mg epinephrine in total and 300 + 150 mg of amiodarone (as well as lidocaine and magnesium sulfate). The cardiac rhythm eventually evolved to asystole, necessitating the intravenous injection of epinephrine to achieve the return of spontaneous circulation. However, critical hemodynamic instability persisted, with the patient's cardiac rhythm alternating between refractory irregular narrow complex tachycardia and wide complex tachycardia associated with hypotension. In an attempt to restore stability we administered three successive doses of Intralipid (120 + 250 + 100 mg), which successfully prevented a severe cardiovascular collapse due to a supra-lethal plasma caffeine level (>120 mg/L after lipid emulsion). The patient survived without any neurologic complications and was transferred to a psychiatric ward a few days later. The case emphasizes the efficacy of intravenous lipid emulsion in the resuscitation of patients from non-local anesthetic systemic toxicity. Intralipid appears to act initially as a vehicle that carries the stimulant drug away from heart and brain to less well-perfused organs (scavenging mechanism) and then, with a sufficient drop in the caffeine concentration, possibly as a tonic to the depressed heart.

Body art among minority high school athletes: prevalence, interest and satisfaction; parental knowledge and consent.

Of 997 minority high school students, 8.6% had tattoos and 8% piercings (excluding earlobes); 21% with tattoos and 59% with piercings would not repeat the experience. Fifty-eight percent with tattoos and 43% with piercings reported parental knowledge before the procedure; 75% and 80%, respectively, were asked for proof of parental consent.

Condom use in incarcerated adolescent males: knowledge and practice.

BACKGROUND: Information is limited on how well adolescents use condoms and where they learn how. OBJECTIVE: The objective of this study was to determine how often incarcerated males used condoms incorrectly and where, how, and from whom they learned condom use. STUDY: This study consisted of an interviewer-administered survey during intake physicals at a juvenile detention center. Results were based on self-report; condom use models were not used. RESULTS: During usual use among 141 males, errors included failure to secure the condom to the penis on withdrawal (37%), loss of erection before condom removal (18%), and failure to leave space at the tip (14%). Learning occurred at home (27%), school (23%), probation/detention facilities (14%), and community programs (3.4%). Subjects learned from educators/counselors (37%), family (27%), and friends (6.9%). Methods of learning included reading the package insert (45%), demonstrations (39%), explanations (33%), and media (19%). CONCLUSIONS: These adolescents had relatively few condom errors. Common methods of learning correct condom use included observing a demonstration, reading the package insert, and hearing an explanation. The last 2 methods are easy to implement.

The epidemiology of sexually transmitted infections in adolescents.

This article addresses the epidemiology of several common sexually transmitted infections (STIs) in adolescents. Chlamydia is a common occurrence in adolescents, more so than is gonorrhea, but both are of particular concern because they may cause pelvic inflammatory disease. Many experts recommend screening for chlamydia in sexually active adolescents, particularly females. Trichomonas vaginalis is significant as a marker for risk of contracting other STIs and because of its association with pregnancy complications and with increased risk of transmission of HIV. Genital herpes simplex virus (HSV) infection, which usually has been caused by HSV-2, is a common finding in adolescents, and it now is caused also by HSV-1 in some populations. Human papillomavirus (HPV), though widespread in adolescents, usually is a self-limited infection, and malignancy resulting from HPV is a rare occurrence in this age group. The least common of the diseases discussed below is syphilis, but a recent sharp increase in incidence has occurred in men who have sex with men.

Self-assessment of circumcision status by adolescents.

In epidemiologic studies of the relation between circumcision and sexually transmitted infections, it is necessary to rely on self-report of circumcision status. The purpose of this 2002 study in Houston, Texas, was to determine whether adolescent males could make correct self-reports. During physical examinations, adolescents were asked whether they were circumcised. The authors then examined the adolescents' genitalia. Circumcision status was recorded as complete (glans penis fully exposed), partial (glans partly covered), or uncircumcised (glans completely covered). The mean age of the 1,508 subjects was 15.0 (standard deviation, 1.63) years; 64% were Black, 29% Hispanic, and 7% White. Forty-nine percent had full, 1% partial, and 50% no circumcision. Of the 738 fully circumcised subjects, 512 (69%) considered themselves circumcised, 54 (7%) considered themselves uncircumcised, and 172 (23%) did not know. Of the 751 uncircumcised youth, 491 (65%) described themselves as uncircumcised, 27 (4%) reported being circumcised, and 233 (31%) did not know. The sensitivity of self-report among those who thought they knew their status was 90.5%, and the specificity was 94.8%; 27% did not know their status. In this population, self-report of circumcision status did not result in accurate information mainly because many adolescents were unsure of their status.

Assessment of competencies in physicians-in-training through the delivery of a community-based health curriculum using distance learning.

Academic physicians must master the elements of curriculum development and evaluation specific to defined competencies in postgraduate medical education. Six fellows in primary care medicine, working as a peer group with a faculty mentor, designed and evaluated a distance-learning project that included resident physicians. Professionalism, interpersonal skills and systems-based medical practice skills were measured with original instruments designed by the peer group. By the process of evaluation and revision in a peer-group setting and with mentorship from program faculty, experiential learning enhanced the training of future academic physicians. This paper describes the background, process and statistical results of their work.