Functional Characterization of p.(Arg160Gln) PCSK9 Variant Accidentally Found in a Hypercholesterolemic Subject.

Familial hypercholesterolaemia (FH) is an autosomal dominant dyslipidaemia, characterised by elevated LDL cholesterol (LDL-C) levels in the blood. Three main genes are involved in FH diagnosis: LDL receptor (LDLr), Apolipoprotein B (APOB) and Protein convertase subtilisin/kexin type 9 (PCSK9) with genetic mutations that led to reduced plasma LDL-C clearance. To date, several PCSK9 gain-of-function (GOF) variants causing FH have been described based on their increased ability to degrade LDLr. On the other hand, mutations that reduce the activity of PCSK9 on LDLr degradation have been described as loss-of-function (LOF) variants. It is therefore important to functionally characterise PCSK9 variants in order to support the genetic diagnosis of FH. The aim of this work is to functionally characterise the p.(Arg160Gln) PCSK9 variant found in a subject suspected to have FH. Different techniques have been combined to determine efficiency of the autocatalytic cleavage, protein expression, effect of the variant on LDLr activity and affinity of the PCSK9 variant for the LDLr. Expression and processing of the p.(Arg160Gln) variant had a result similar to that of WT PCSK9. The effect of p.(Arg160Gln) PCSK9 on LDLr activity is lower than WT PCSK9, with higher values of LDL internalisation (13%) and p.(Arg160Gln) PCSK9 affinity for the LDLr is lower than WT, EC50 8.6 ± 0.8 and 25.9 ± 0.7, respectively. The p.(Arg160Gln) PCSK9 variant is a LOF PCSK9 whose loss of activity is caused by a displacement of the PCSK9 P' helix, which reduces the stability of the LDLr-PCSK9 complex.

Prolonged Background Suppression Induced by Anticonvulsants Misleading Amplitude-Integrated Electroencephalography's Interpretation: A Single Case Report.

Prognostic role of the amplitude-integrated electroencephalography (aEEG) is undeniable, but few works focused on the contribution of medications in misleading its interpretation. We report the case of an asphyxiated newborn enrolled for therapeutic hypothermia (TH) that required the simultaneous use of three anticonvulsants, whose administration resulted in a comatose state and in a switch to a flat trace on the aEEG. The prolonged flat trace on the aEEG, pointing toward a state of irreversible brain damage, led to early stop of TH to prevent therapeutic obstinacy; unexpectedly, once Midazolam was weaned off, the aEEG recovered to a discontinuous pattern. The case emphasizes the aEEG's noninfallibility and advises clinicians to consider the potential misleading effects of depressant medications on its interpretation in asphyxiated newborns undergoing TH.

Photoinduced charge separation in functional carbon-silver nanohybrids.

In recent times, nanoscience is devoting growing interest to the easy assembly of well-established nanomaterials into hybrid nanostructures displaying new emerging features. Here, we study the photophysicochemical response of binary nanohybrids obtained by the spontaneous coupling of luminescent carbon dots to silver nanoparticles with controlled surface charge. Evidence of the successful coupling is obtained by steady-state and time resolved optical measurements and further confirmed by direct imaging. We demonstrate strong interactions within nanohybrids, which can be modelled in terms of a sub-picosecond electron transfer from photoexcited carbon dots to silver nanoparticles. Accordingly, newly designed nanohybrids display significant photocatalytic performance demonstrated by the photodegradation of methylene blue under ultraviolet-visible light. Our results provide an exhaustive picture of the optical response of these self-assembled carbon-silver nanohybrids and show their promise as a new class of eco-friendly materials for light-driven catalytic applications.

Search for familial hypercholesterolemia patients in an Italian community: A real-life retrospective study.

BACKGROUND AND AIMS: Familial hypercholesterolemia (FH) is a common inherited disorder of low-density lipoprotein (LDL) catabolism that causes elevated LDL-cholesterol (LDL-C) and premature atherosclerotic cardiovascular disease (ASCVD). Despite the availability of effective treatments, FH remains underdiagnosed and undertreated. The aims of the study were to identify putative FH subjects using data from laboratory and cardiology databases, genetically characterize suspected FH patients referred to the Lipid Clinic and monitor attainment of treatment goals in identified patients. METHODS AND RESULTS: We retrieved the electronic health records of 221,644 individuals referred to laboratory for routine assessment and of 583 ASCVD patients (age ≤65) who underwent percutaneous transluminal coronary angioplasty (PTCA). We monitored the lipid profiles of subjects with LDL-C ≥ 250 mg/dl identified by laboratory survey (LS-P), PTCA patients and patients from the Lipid Clinic (LC-P). The laboratory survey identified 1.46% of subjects with LDL-C ≥ 190 mg/dl and 0.08% with LDL-C ≥ 250 mg/dl. Probable/definite FH was suspected in 3% of PTCA patients. Molecularly-confirmed FH was found in 44% of LC-P subjects. Five new LDLR mutations were identified. The 50% LDL-C reduction target was achieved by 70.6% of LC-P patients. Only 18.5% of PTCA patients reached the LDL-C < 55 mg/dl target. CONCLUSION: By using a combined approach based on laboratory lipid profiles, documented ASCVD and Lipid Clinic data, we were able to identify subjects with a high probability of being FH. Attainment of LDL-C goals was largely suboptimal. Efforts are needed to improve FH detection and achievement of lipid targets.

Cross-Lagged Relations Between Exercise Capacity and Psychological Distress During Cardiac Rehabilitation.

Background: Poorer mental health is associated with lower exercise capacity, above and beyond the effect of other cardiovascular risk factors. However, the directionality of this relationship remains unclear. Purpose: The main aim of the present study was to clarify, with a cross-lagged panel design, the relationship between psychological status and exercise capacity among patients in a cardiac rehabilitation (CR) program. Methods: A clinical sample of 212 CR patients completed exercise-capacity testing and measures of depression and anxiety (Hospital Anxiety and Depression Scale) pre-CR and post-CR. Demographic and clinical data, including BMI and smoking history, were also collected. Multivariate stepwise regression analysis was performed to identify the best predictors of exercise capacity at discharge. Structural equation modeling was utilized to quantify the cross-lagged effect between exercise capacity and psychological distress. Results: Multivariate regression analysis revealed that higher levels of psychological distress pre-CR are predictively associated with less improvement in exercise capacity post-CR, beyond the effects of age, sex, and baseline functional status. Results from structural equation modeling supported a 1-direction association, with psychological distress pre-CR predicting lower exercise capacity post-CR over and above autoregressive effects. Conclusions: Study results did not support the hypothesis of a bidirectional relationship between psychological distress and EC. High levels of psychological distress pre-CR appeared to be longitudinally associated with lower exercise capacity post-CR, but not vice versa. This finding highlights the importance of assessing and treating both anxiety and depression in the early phase of secondary prevention programs.

A Steep-Slope Transistor Combining Phase-Change and Band-to-Band-Tunneling to Achieve a sub-Unity Body Factor.

Steep-slope transistors allow to scale down the supply voltage and the energy per computed bit of information as compared to conventional field-effect transistors (FETs), due to their sub-60 mV/decade subthreshold swing at room temperature. Currently pursued approaches to achieve such a subthermionic subthreshold swing consist in alternative carrier injection mechanisms, like quantum mechanical band-to-band tunneling (BTBT) in Tunnel FETs or abrupt phase-change in metal-insulator transition (MIT) devices. The strengths of the BTBT and MIT have been combined in a hybrid device architecture called phase-change tunnel FET (PC-TFET), in which the abrupt MIT in vanadium dioxide (VO2) lowers the subthreshold swing of strained-silicon nanowire TFETs. In this work, we demonstrate that the principle underlying the low swing in the PC-TFET relates to a sub-unity body factor achieved by an internal differential gate voltage amplification. We study the effect of temperature on the switching ratio and the swing of the PC-TFET, reporting values as low as 4.0 mV/decade at 25 °C, 7.8 mV/decade at 45 °C. We discuss how the unique characteristics of the PC-TFET open new perspectives, beyond FETs and other steep-slope transistors, for low power electronics, analog circuits and neuromorphic computing.

Fatal Intoxications in the North of Portugal: 12 Years of Retrospective Analysis.

BACKGROUND: Fatal intoxications are a topic of great relevance in today's society. They typically occur by accidental or voluntary ingestion, but its characterization by a forensic perspective was not fully explored. OBJECTIVE: This study retrospectively reviews fatal intoxication cases autopsied at the northern forensic medicine services of Portugal, between 2001 and 2013. METHOD: For this purpose, we analyzed postmortem forensic medical reports with positive qualitative analysis for xenobiotics. RESULTS: A total of 27,778 autopsy reports were analyzed, of which 1,269 cases fulfilled the selection criteria, representing 4.6% of total number of individuals autopsied during the period under analysis. Men were involved in most of the cases (73.8%) and most individuals were adults with ages between 36 and 65 years old (57.0%). The highest incidences were medicines (22.9%) and alcohol (15.8%), followed by their association. Cases of fatal intoxications involving opioids come on fifth place (5.8%) namely due to accidental overdoses. Moreover, intoxications appeared as the leading cause of death in reports concerning accidental etiology, with drugs and alcohol associations having a great expression. CONCLUSION: Due to morbidity and relevant number of fatal cases, risk prevention measures, such as public health policies should be implemented to reduce the number of intoxications.

Development and initial validation of the Cardiovascular Disease Acceptance and Action Questionnaire (CVD-AAQ) in an Italian sample of cardiac patients.

Psychological inflexibility refers to the attempt to decrease internal distress even when doing so is inconsistent with life values, and has been identified as a potential barrier to making and maintaining health behavior changes that are consistent with a heart-healthy lifestyle. Disease- and behavior-specific measures of psychological inflexibility have been developed and utilized in treatment research. However, no specific measure has been created for patients with heart disease. Thus, the CardioVascular Disease Acceptance and Action Questionnaire (CVD-AAQ) was developed. The present study is aimed to evaluate the psychometric properties of the CVD-AAQ and to explore its association with measures of psychological adjustment and cardiovascular risk factors in an Italian sample of 275 cardiac patients. Exploratory factor analysis showed a structural one-factor solution with satisfactory internal consistency and test-retest reliability. The relation with other measures was in the expected direction with stronger correlations for the theoretically consistent variables, supporting convergent and divergent validity. CVD-AAQ scores were associated with general psychological inflexibility, anxiety and depression and inversely correlated with psychological well-being. Moreover, the results showed that CVD-AAQ scores are associated with two relevant risk factors for cardiac patients, namely low adherence to medication and being overweight. In sum, results suggest that the CVD-AAQ is a reliable and valid measure of heart disease-specific psychological inflexibility with interesting clinical applications for secondary prevention care.

Erros inatos do metabolismo confirmados no Hospital das Clínicas de Ribeirão Preto-SP no período de 2000 a 2008 / Inborn errors of metabolism in the Hospital of Clinics of Ribeirão Preto - SP from 2000 to 2008

Os Erros Inatos do Metabolismo (EIM) vêm sendo cada vez mais identificados nos últimos anos. A preocupação com o diagnóstico precoce decorre do foco na prevenção de deficiências, especialmente a mental. Este estudo descritivo teve por objetivo verificar diagnósticos confirmados e modalidades de tratamento utilizadas de janeiro de 2000 a dezembro de 2008. Método: foi realizada busca ativa de casos confirmados nos serviços que atendem esse tipo doença: neurologia (neuropediatria e doençasneuromusculares), pediatria (serviço de gastrologia e hepatologia) e genética clínica, além de levantamento no Serviço de Arquivo Médico do HCFMRP-USP. Foram confirmados 165 pacientes com EIM, com idades de um dia a 22 anos (mediana de um ano); 50 casos foram defeitos na síntese ou catabolismo de moléculas complexas, 65 no metabolismo intermediário, e 50 na produção ou utilização de energia. O tratamento foi instituído para 12 dos 50 pacientes do grupo I sendo reposição enzimática em 11 e transplante de medula óssea em um; todos do grupo II e III receberam orientação nutricional; 60 do grupo II receberam fórmula dietética industrializada; dos 50 do grupo III, 43 com mitocondriopatias receberam L-carnitina e coenzimas e aqueles com glicogenose, orientação sobre aporte de carbohidratos. A formação de novos recursos humanos, integração com a Rede EIM Brasil e linhas de pesquisa na área são prioridades para melhorar a acuidade na detecção e tratamento de erros inatos do metabolismo.

Inborn Errors of Metabolism have been increasingly identified in recent years. The early diagnosis focuses on prevention of disabilities, especially mental retardation. This descriptive study aims to verify confirmed diagnosis and treatment modalities in HCFMRP-USP cases from January of 2000 to December of 2008. A total of 165 patients with ages ranging from one day to 22 years (median one year) were detected. Fifty patients had synthesis or catabolism of complex molecules (group I), 65 intermediary metabolism (group II), and 50 had production or use of energy (group III) defects. Among the patients of group I, 11 had enzyme replacement therapy, and one bone marrow transplantation; for group II and III, inaddition to daily nutritional guidance for all of the patients, 60 from group II received industrialized diets; from group III, 43 with mitochondrial diseases received L-carnitine and coenzymes, and those with glycogenosis were focused mainly on the intake of carbohydrates. New human resources, integration with the Network EIM Brazil and lines of research in the area are priorities for improving the accuracy in the detection and treatment of inborn errors of metabolism.

Protein crystallization: universal thermodynamic vs. specific effects of PEG.

The interest of nucleation of protein crystals and aggregates (including oligomerization) spans from basic physics theory all the way to biophysics, nanophysics, clinical sciences, biotechnologies, food technologies and polymer-solvent interactions. Understanding nucleation within a theoretical framework capable of providing quantitative predictions and control of nucleation rates, or even the very occurrence of crystallization, is a long-sought goal of remarkable relevance to each of the above fields. A large amount of work has been aimed at such goal, but success has been so far rather limited. Work at our laboratory has more recently highlighted a direct link between nucleation rates and the universal scaling properties of concentration fluctuations occurring in the vicinity of a phase transition. The phase transition here concerned is that of non nucleated liquid-liquid demixing of the solution. This novel universality feature allows viewing nucleation processes within one and the same frame, and to capture all normalized nucleation rates on one and the same "master curve" for different proteins, as a function of one parameter only. The quantitative value of the latter is the result of the joint, non additive effects of protein composition, conformation and state (e.g. oligomers), as well as of the temperature of non nucleated liquid-liquid demixing of the solution at the given protein concentration and at the given conditions of the solution. The present work was undertaken for the purpose of ascertaining if (and if so, in what way) the universality feature can allow the quantitative prediction of nucleation rates changes caused by the addition to the solvent of additives empirically known for their strong effect on such rates, as well as the very occurrence of crystallization. To this purpose we have used PEG (polyethylene glycol), which is perhaps the most familiar and most-used additive, and have measured by static and dynamic light scattering the properties of concentration fluctuation of the system as a function of temperature, for various PEG concentration and polymerisation degrees. Experiments have shown that the action of PEG can in no way be accounted for in terms of changes of specific local contacts or of a one-to-one chaperone-like action. Instead, the effect of PEG is seen to be due to alteration of the thermodynamic properties of the solution. This leaves unchanged the universality features and consequently also the validity and predictive power of the master curve in the various conditions.

Protein aggregation/crystallization and minor structural changes: universal versus specific aspects.

Protein association covers wide interests in biophysics, protein science, and biotechnologies, and it is often viewed as governed by conformation details. More recently, the existence of a universal physical principle governing aggregation/crystallization processes has been suggested by a series of experiments and shown to be linked to the universal scaling properties of concentration fluctuations occurring in the proximity of a phase transition (spinodal demixing in the specific case). Such properties have provided a quantitative basis for capturing kinetic association data on a universal master curve, ruled by the normalized distance of the state of the system from its instability region. Here we report new data on lysozyme crystal nucleation. They strengthen the evidence in favor of universality and show that the system enters the region of universal behavior in a stepwise manner as a result of minor conformation changes. Results also show that the link between conformation details and universal behavior is actuated by interactions mediated by the solvent. Outside the region of universal behavior, nucleation rates become unpredictable and undetectably long.

Effect of T-R conformational change on sickle-cell hemoglobin interactions and aggregation.

We compare the role of a conformational switch and that of a point mutation in the thermodynamic stability of a protein solution and in the consequent propensity toward aggregation. We study sickle-cell hemoglobin (HbS), the beta6 Glu-Val point mutant of adult human hemoglobin (HbA), in its R (CO-liganded) conformation, and compare its aggregation properties to those of both HbS and HbA in their T (unliganded) conformation. Static and dynamic light scattering measurements performed for various hemoglobin concentrations showed critical divergences with mean field exponents as temperature was increased. This allowed determining spinodal data points T(S)(c) by extrapolation. These points were fitted to theoretical expressions of the T(S)(c) spinodal line, which delimits the region where the homogeneous solution becomes thermodynamically unstable against demixing in two sets of denser and dilute mesoscopic domains, while remaining still liquid. Fitting provided model-free numerical values of enthalpy and entropy parameters measuring the stability of solutions against demixing, namely, 93.2 kJ/mol and 314 J/ degrees K-mol, respectively. Aggregation was observed also for R-HbS, but in amorphous form and above physiological temperatures close to the spinodal, consistent with the role played in nucleation by anomalous fluctuations governed by the parameter epsilon = (T - T(S))/T(S). Fourier transform infrared (FTIR) and optical spectroscopy showed that aggregation is neither preceded nor followed by denaturation. Transient multiple interprotein contacts occur in the denser liquid domains for R-HbS, T-HbS, and T-HbA. The distinct effects of their specific nature and configurations, and those of desolvation on the demixing and aggregation thermodynamics, and on the aggregate structure are highlighted.

Effect of inhalation aspirin challenge on exhaled nitric oxide in patients with aspirin-inducible asthma.

BACKGROUND: A complex relationship between arachidonic acid metabolites and nitric oxide (NO) synthesis has been reported in asthma. The effects of inhaled aspirin on fractional exhaled NO (FENO) in patients with aspirin-tolerant (ATA) and aspirin-inducible (AIA) asthma compared with normal controls have been investigated. METHODS: The FENO was measured baseline, after saline and lysine-aspirin (L-ASA) bronchial challenge in 10 patients with ATA and in 10 patients with AIA [mean (PD(20)FEV(1) L-ASA): 14.7 +/- 12.7 mg], who had comparable age and baseline FEV(1). Ten healthy subjects served as controls. Sputum eosinophils were counted after saline and after L-ASA challenge in the two groups of asthmatics. RESULTS: Asthmatic patients had baseline FENO significantly higher than controls (29.7 +/- 6.8 vs 9.8 +/- 2.05 p.p.b. respectively, P < 0.0001). No difference was observed in methacholine PD(20)FEV(1) and baseline FENO between ATA and AIA patients. After L-ASA inhalation, FENO increased significantly only in patients with AIA, reaching the peak value 4 h after bronchoconstriction (from 31.1 +/- 6 to 43 +/- 4.8 p.p.b., P < 0.001), while no change was observed in patients with ATA and in controls. Sputum eosinophils increased significantly after L-ASA inhalation only in patients with AIA (from 8.1 +/- 2.7 to 11.1 +/- 2.8%, P < 0.005) and there was a significant relationship between the increase in sputum eosinophils and the increase in FENO after ASA challenge. CONCLUSION: Exhaled NO may indicate eosinophilic airway inflammation during ASA exposure in patients with ASA inducible asthma.

Irreversible formation of intermediate BSA oligomers requires and induces conformational changes.

Understanding the relation between protein conformational changes and aggregation, and the physical mechanisms leading to such processes, is of primary importance, due to its direct relation to a vast class of severe pathologies. Growing evidence also suggests that oligomeric intermediates, which may occur early in the aggregation pathway, can be themselves pathogenic. The possible cytotoxicity of oligomers of non-disease-associated proteins adds generality to such suggestion and to the interest of studies of oligomer formation. Here we study the early stages of aggregation of Bovine Serum Albumin (BSA), a non pathogenic protein which has proved to be a useful model system. Dynamic light scattering and circular dichroism measurements in kinetic experiments following step-wise temperature rises, show that the "intermediate" form, which initiates large-scale aggregation, is the result of structural and conformational changes and concurrent formation of oligomers, of average size in the range of 100-200 A. Two distinct thresholds are observed. Beyond the first one oligomerization starts and causes partial irreversibility of conformational changes. Beyond the second threshold, additional secondary structural changes occurring in proteins being recruited progress on the same time scale of oligomerization. The concurrent behavior causes a mutual stabilization of oligomerization, and of structural and conformational changes, evidenced by a progressive increase of their irreversibility. This process interaction appears to be pivotal in producing irreversible oligomers.

The influence of surface modification on the cytotoxicity of PAMAM dendrimers.

The influence of surface modification on the cytotoxicity of PAMAM dendrimers was examined using Caco-2 cells. Dendrimers were modified by conjugating either lauroyl chains or polyethylene glycol (PEG) 2000 onto the surface of cationic PAMAM dendrimers (G2, G3, G4). The cytotoxicity of unmodified dendrimers towards Caco-2 cells was appreciably higher for cationic (whole generation) compared with anionic (half generation) dendrimers and for both types increased with increasing size (generation) and concentration. A marked decrease in the cytotoxicity of cationic PAMAM dendrimers was noted when the surface was modified, with the addition of six lauroyl or four PEG chains being particularly effective in decreasing cytotoxicity. This decrease in cytotoxicity is thought to be due to a reduction/shielding of the positive charge on the dendrimer surface by the attached chains. The cytotoxicity of dendrimer-based delivery systems is likely to be very different from the parent dendrimer.

On-off transport through a thermoresponsive hydrogel composite membrane.

A novel thermoresponsive composite membrane is described through which the permeation of molecules is dependent on the temperature of the milieu. The thermoresponsive composite membranes utilise a thermosensitive crosslinked polymeric hydrogel, which possesses a volume phase transition temperature (VPTT). The hydrogel was polymerised in situ within the pores of a sintered glass filter, through which significant permeation of molecules only occurred at temperatures above the VPTT of the hydrogel. It was found that the permeation of molecules through the thermoresponsive composite membranes could be modulated by changing the environmental temperature.

Interaction of processes on different length scales in a bioelastomer capable of performing energy conversion.

This work concerns the aggregation properties of (Gly-Val-Gly-Val-Pro)(251) rec, a polypentapeptide reflecting a highly conserved repetitive unit of the bioelastomer, elastin. On raising the temperature of aqueous solutions above 25 degrees C, this polypeptide was already known to undergo concurrent conformational changes (hydrophobic folding), phase separation, and self-assembly with formation of aggregated three-stranded filaments composed of dynamic polypeptide helices, called beta-spirals. Aggregates obtained from the solution can be shaped into bands that acquire entropic elastic properties upon gamma-irradiation and can perform a variety of energy conversions. Previous studies have shown that aggregation is prompted by the (diverging) critical fluctuations of concentration occurring in the solution, in vicinity of its spinodal line. Here, we present combined circular dicroism (CD) and light scattering experiments, and independent fittings of experimental data to the theoretical spinodal and binodal (coexistence) lines. Results show the following logical and causal sequence of processes: (a) Smooth and progressive conformational changes promoted by concentration fluctuations occurring as temperature is raised "pull down" (in the temperature scale) the instability region of the solution. (b) This further promotes critical fluctuations. (c) The related locally high concentration prompts a further substantial conformational change ending in triple-helix formation and coacervation. (d) This intertwining of processes, covering different length scales (from that of individual peptides to the mesoscopic one of demixed regions), is related to the fact that solvent-induced interactions play a strong role over the entire scale span. These results concur with other recent ones in pointing out that process interactions over many length-scales probably reflect a frequent if not ubiquitous pattern in protein aggregation. This may be highly relevant to the desirable deep understanding of such phenomenon, whose interests cover many fields.

The role of solvent in protein folding and in aggregation.

We discuss features of the effect of solvent on protein folding andaggregation, highlighting the physics related to the particulate nature and the peculiar structure of the aqueous solvent, and the biological significance of interactions between solvent and proteins. To this purpose we use a generalized energy landscape of extended dimensionality. A closer look at the properties of solvent induced interactions and forces proves useful for understanding the physical grounds of `ad hoc' interactions and for devising realistic ways of accounting for solvent effects. The solvent has long been known to be a crucially important part of biological systems, and times appear mature for it to be adequately accounted for in the protein folding problem. Use of the extended dimensionality energy landscape helpseliciting the possibility of coupling among conformational changes and aggregation, such as proved by experimental data in the literature.

Polyamidoamine Starburst dendrimers as solubility enhancers.

The solubility of the hydrophobic drug ibuprofen has been compared in an aqueous solution of polyamidoamine (PAMAM) G4 dendrimer and sodium dodecyl sulphate (SDS). The PAMAM G4 dendrimer solution significantly enhanced the solubility of ibuprofen compared to 2% SDS solution. It was found that the solubility of ibuprofen in dendrimer solution was directly proportional to dendrimer concentration and inversely proportional to temperature. The influence of dendrimer solution pH on the solubility enhancement of ibuprofen suggests that it involves an electrostatic interaction between the carboxyl group of the ibuprofen molecule and the amine groups of the dendrimer molecule.

Interacting processes in protein coagulation.

A strong interest is currently focused on protein self-association and deposit. This usually involves conformational changes of the entire protein or of a fragment. It can occur even at low concentrations and is responsible for pathologies such as systemic amyloidosis, Alzheimer's and Prion diseases, and other neurodegenerative pathologies. Readily available proteins, exhibiting at low concentration self-association properties related to conformational changes, offer very convenient model systems capable of providing insight into this class of problems. Here we report experiments on bovine serum albumin, showing that the process of conformational change of this protein towards an intermediate form required for coagulation occurs simultaneously and interacts with two more processes: mesoscopic demixing of the solution and protein cross-linking. This pathway of three interacting processes allows coagulation even at very low concentrations, and it has been recently observed also in the case of a nonpeptidic polymer. It could therefore be a fairly common feature in polymer coagulation/gelation. Proteins 1999;37:116-120.