Cluster phases of decorated micellar solutions with macrocyclic ligands

An aqueous self-assembled micellar system (sodium dodecyl sulfate, SDS, decorated with various adhesive sites, cryptand Kryptofix 222 and crown ether 18-Crown-6 molecules) has been investigated by dynamic light scattering (DLS) and small angle x-ray scattering (SAXS) to have insights into the micellar structure, the micellar interactions, and the aggregation properties of the system. DLS demonstrates the existence of populations of aggregates in the submicrometer/micrometer range, while the Guinier analysis of the SAXS curves helps in detailing objects smaller than 30 nm. The aggregates of micelles are here named cluster phases of micelles (CPMs). Considering that SDS micelles in water do not aggregate at low concentration, it is shown that macrocyclic ligands induce the SDS micelle aggregation as a function of the concentration (i.e., investigated ligand/SDS molar ratios are 5.0, 1.5, 1.0, and 0.5) and hydrophobicity of the adhesive sites. The sizes and the percentages of the micelles and the CPMs have been monitored to test the stability and reversibility of the system. DLS results clearly show that the aggregation processes of the decorated micelles are reproducible at time intervals of the order of 1 month, while the stability may not be entirely maintained after a year. As an issue of particular relevance, the higher the ligand/surfactant molar ratio, the larger are the CPMs induced. The K222 ligand results in being more effective in promoting the micellar aggregation than 18C6 as a consequence of the different hydrophobicity.

Prevention of acute renal failure post-contrast imaging in cardiology: a randomized study

BACKGROUND

The contrast-induced nephropathy (CIN) is the third most common cause of acute renal failure (ARF) and the worsening in a pre-existing chronic renal failure (CRF), with a foreseeable increase of morbidity, mortality, length of the stay in hospital and, as a consequence, of the health costs. We studied the effectiveness of N-acetylcysteine (NAC) associated with sodium bicarbonate (Na2HCO3) infusion in order to prevent CIN in patients undergoing coronary angiography with administration of contrast medium.

MATERIALS AND METHODS

296 patients with indication to perform coronary angiography were included in a randomized, observational study. All patients were randomly assigned to receive pre- and post-contrast hydration with 1500 ml of 0.9% saline solution infusion (Group A) or NAC (1200 mg × 2 days) + Na2HCO3 (Group B). The primary end-point was to examine CIN appearance, defined as a raise in serum values of Cr (Creatinine) ≥ 0.5 mg/dl or ≥ 25% within 24-72 hours after the exposure to the contrast medium.

RESULTS

It has been observed a frequency of CIN of 9.4% in Gr. A compared to 7.2% in Gr. B. Nevertheless, when we put these results through a more accurate screening according to gender, degree of raise in creatinine levels and the extent of change in GFR (glomerular filtration rate), we observed a very different behaviour. In patients with normal Cr and CrCl (Clearance of Creatinine) the frequency of CIN was similar in both group A and B (approximately 5%). In patients with normal Cr but reduced ClCr the use of NAC was more effective than hydration in preventing CIN (0% vs 18% in prevalence respectively in B and A group). In patients with moderately reduced Cr and CrCl, hydration with saline solution was more effective than NAC + Na2HCO3 (8.6% vs 17.6%) while in patients with severe CRF the combined use of NAC + Na2HCO3 showed off to be very successful in preventing CIN compared to the merely hydration (0% vs 50%).

CONCLUSIONS

In patients affected by severe CRF who are undergoing investigations with contrast medium administration, such as coronary angiography, the combined use of NAC + Na2HCO3 infusion significantly reduces the risk of developing CIN. In other circumstances the final result is related to the degree of previous GFR or creatinine values alteration or to gender. In such situations the combined use of both substances is more questionable and sometimes ineffective.

The role of extracellular conditions during CaCo-2 cells growth: a preliminary study for numerical model validation

OBJECTIVES

One important limitation in cell therapy protocols, and regenerative medicine (an innovative and promising strategy for different pathologies treatment), is the lack of knowledge about cells engraftment, proliferation and differentiation. In order to allow an efficient and successful cell transplant, it is necessary to predict the logistics, economic and timing issues during cellular injection. It has been reported that several parameters, such as cells number, temperature and extracellular pH (pH0) value can influence metabolic pathways and cellular growth. Numerical analysis and model can help to reduce and understand the effects of the above environmental conditions on cell survival. The aim of this paper is to develop the first step of cells transplantation in order to identify "in vitro", which parameters can be useful to develop and validate a numerical model, able to evaluate "in vivo" cells engraftment and proliferation.

MATERIAL AND METHODS

We studied the variation of extracellular parameters--such as medium volume, buffer system, nutrient concentrations and temperature on human colon carcinoma cells (CaCo-2) "in vitro culture"--pursuing the goal of understanding in deeper details cellular processes such as growth, metabolic activity, survival and pH0.

RESULTS

Results showed that CaCo-2 cells growth and mortality increase after two days in culture when cells were suspended in 3.5 ml volume to respect of 10 ml volume. Different temperature values influenced CaCo-2 cells growth and metabolic activity showing a direct relationship with the volume of the medium.

CONCLUSIONS

Our results describe as CaCo-2 cell growth, metabolic activity, mortality and extracellular pH were influenced by extracellular parameters, enabling us to develop and validate a numerical model to be use to predict cells engraftment and proliferation.

Myocardial ischemia in cocaine-user with anomalous origin of the left circumflex coronary artery

The prevalence of anomalous coronary artery is approximately 0.6-1.7% in patients who undergo coronary angiography. These anomalies may cause angina, acute myocardial infarction, syncope and sudden death. Cocaine abuse is now a major health hazard: more than 5 million of Americans are current users. Cocaine abuse can result in coronary artery vasocostriction and the association between cocaine abuse, myocardial ischemia and infarction in the absence of coronary artery disease has been reported. We report the case of a patient with a story of nasally inhaled cocaine abuse presented with exertional chest pain and a perfusion defect of the anterior and inferior-lateral walls of the left ventricle during myocardial perfusion SPECT. The anomalous origin of the left circumflex coronary artery from the righ sinus of Valsalva was detected during coronary angiography and confirmed by the multislice computed tomography (MSCT). Although the coronary angiography is the gold standard of cardiac imaging technique for the diagnosis of coronary artery disease the identification of anomalous coronary arteries is frequently difficult with conventional coronary angiography because of the lack of 3-dimensional (3D) information related to the course of the coronary arteries to the great vessels. The MSCT provides a high spatial resolution, which allows a successful identification of the congenital coronary artery anomalies. This case report provides further a supportive evidence for the role of MSCT in the detection of the coronary artery anomalies.

Elasticity/distensibility of the ascending aorta: basal conditions and simulated conditions from space flights

INTRODUCTION

The hysto-morfological composition of the ascending aorta wall gives to the vessel its characteristic elasticity/distensibility, which is deteriorated due to both physiological (age) and pathological events (hypertension, diabetes, dyslipidemia). This contributes to reduce the wall elasticity and to occurrence of cardiovascular events.

MATERIALS AND METHODS

Thirty young healthy subjects (20 males, 10 females, age <30 yr), were subjected to different postural conditions with and without Lower Body Negative Pressure (LBNP) with conventional procedures, to simulate the microgravity conditions in space flight. During this procedure the cardiovascular parameters and the aorta elasticity were assessed with ecocardiography.

RESULTS

The observation of results and statistical comparison showed that despite different hemodynamic conditions and with significant variation of blood pressure related to posture, elasticity/distensibility did not change significantly.

DISCUSSION

The elasticity/distensibility of arterial vessels is the result of two interdependent variables such as blood pressure and systolic and diastolic diameters. While blood pressure and heart rate vary physiologically in relation to posture, the compensation of the vessel diameters modifications maintains the aortic compliance invariate. Therefore, in young healthy people, despite the significant postural and the sudden pressure changes (equivalent to parietal stress) aortic compliance does not alter. This behavior might be related to the low rate of cardiovascular events that are present in healthy people aged under 30 yrs.

Implementation on a desktop computer of the real time feedback control loop of a scanning probe microscope

A software package has been developed to implement the real time feedback control loop needed in scanning probe microscopy on a general purpose desktop computer of the current high-speed/multicore generation. The main features of the implementation of both the feedback loop and the control of the experiment on the same computer are discussed. The package can work with several general purpose data acquisition boards and can be extended in a modular way to further board models; timing performance has been tested with several hardware configurations and some applications common in scanning probe microscopy. The package is available under an Open Source license.

Dynamic light scattering and atomic force microscopy imaging on fragments of beta-connectin from human cardiac muscle

In order to investigate the protein folding-unfolding process, dynamic light scattering (DLS) and atomic force microscopy (AFM) imaging were used to study two fragments of the muscle cardiac protein beta-connectin, also known as titin. Both fragments belong to the I band of the sarcomer, and they are composed of four domains from I(27) to I(30) (tetramer) and eight domains from I(27) to I(34) (octamer). DLS measurements provide the size of both fragments as a function of temperature from 20 up to 86 degrees C, and show a thermal denaturation due to temperature increase. AFM imaging of both fragments in the native state reveals a homogeneous and uniform distribution of comparable structures. The DLS and AFM techniques turn out to be complementary for size measurements of the fragments and fragment aggregates. An unexpected result is that the octamer folds into a smaller structure than the tetramer and the unfolded octamer is also smaller than the unfolded tetramer. This feature seems related to the significance of the hydrophobic interactions between domains of the fragment. The longer the fragment, the more easily the hydrophobic parts of the domains interact with each other. The fragment aggregation behavior, in particular conditions, is also revealed by both DLS and AFM as a process that is parallel to the folding-unfolding transition.

A study of the ionic conduction of mica surface by admittance spectroscopy

The ionic conduction on the surface of humid mica has been analyzed by admittance spectroscopy as a function of relative humidity for different surface treatments. Measurements at low frequency indicate that water adsorption proceeds first in the form of a strongly adsorbed uniform thin layer, then with the formation of highly inhomogeneous thick aggregates.

Mitochondrial optic neuropathies: how two genomes may kill the same cell type?

Ocular involvement is a prevalent feature in mitochondrial diseases. Leber's hereditary optic neuropathy (LHON) and dominant optic atrophy (DOA) are both non-syndromic optic neuropathies with a mitochondrial etiology. LHON is associated with point mutations in the mitochondrial DNA (mtDNA), which affect subunit genes of complex I. The majority of DOA patients harbor mutations in the nuclear-encoded protein OPA1, which is targeted to mitochondria and participates to cristae organization and mitochondrial network dynamics. In both disorders the retinal ganglion cells (RGCs) are specific cellular targets of the degenerative process. We here review the clinical features and the genetic bases, and delineate the possible common pathomechanism for both these disorders.