A study of factors affecting nucleation and bubble growth in pressurised metered dose inhalers

Various hypotheses have been introduced to explain disintegration of the continuous liquid phase into individual droplets leading to spray formation in pressurised metered dose inhalers (pMDIs). In a practicable system, the liquid formulation to be discharged from the pressurised container needs to be nucleated to ensure spray generation. Nucleation can be described as the generation of a nucleus of the vapour phase within the bulk liquid. As a stable nucleus is formed, it grows significantly and then detaches from its nucleation site to move upwards in the liquid phase. In our research, the effects of various parameters on the nucleation of HFA227 was analysed with the aim of gaining a better understanding of bubble formation and the nucleation process in HFA propellants, including the surface geometrical properties, actuator orifice size and the mass flow rate through the orifice. Other important factors influencing the nucleation process that were considered comprised the viscosity and surface tension of the formulation, thermodynamic state variables including temperature, pressure and degree of superheat. The results highlighted the effect of surface imperfections on the rate of nucleation and bubble growth. A comparison of two different orifice sizes was made and a significant change in the shape and motion of the bubbles was observed. An intense nucleation was also observed at higher mass flow rate of HFA227 through the valve. It is anticipated that recognising the factors affecting nucleation and bubble growth of HFA227 may lead to potential routes of influencing the medical aerosol generation mechanism inside the pMDI and control the fine particle size distribution

Anatomical differences in the right and left renal arterial patterns

The aim of this study was to determine the pattern and character of the renal arteries in patients referred for preoperative or diagnostic evaluation of the renal or abdominal arteries by multi-detector computed tomography and, by comparing the arterial anatomy of the right and left kidneys, to evaluate the effect of differences in their anatomical position on the characteristics of the arteries. During a cross-sectional study from August 2005 to October 2007, 117 patients underwent contrast-enhanced 64-slice multi-detector computed tomography renal angiography in Tabriz Imam Khomeini Hospital (Parsian Centre). The number of arteries, the number of branches and the presence of accessory arteries and early branching were assessed in the renal arteries on both sides. In all, the data for 117 patients data were analysed, 76 (65%) of whom were male and 41 (35%) female. The mean of age of the patients was 39.26 ± ± 17.03 years. The mean diameters of the aorta and renal artery were 2.62 ± ± 1.55 mm and 0.62 ± 0.11 mm respectively and the distance to branching was 3.39 ± 1.59 mm. There was no significant difference in diameter between the left and right renal arteries or in the distance to branching (0.62 ± 0.11 vs. 0.61 ± 0.12 mm; p = 0.35; 3.24 ± 1.2 vs. 3.56 ± 1.77 mm; p = 0.11). An accessory artery was presented in 58 kidneys and this significantly more often occurred on the right side than on the left side: 38 of 117 (32.47%) right kidneys vs. 20 of 117 (17.09%) left kidneys (p = 0.01). There was early branching in 42 subjects (35.89%). In a comparison of early branching of the arteries of the right and left kidneys, no significant difference was found, despite the higher incidence of branching on the right side. The diameters of the right and left renal arteries and the distances to branching did not differ. Apart from width, there was no difference in kidney size. An accessory artery occurred more frequently in the right renal artery than in the left. (Folia Morphol 2008; 67: 104-110

A study of factors affecting nucleation and bubble growth in pressurised metered dose inhalers [Abstract]

A study of factors affecting nucleation and bubble growth in pressurised metered dose inhalers [Abstract

Effect of dietary honey on intestinal microflora and toxicity of mycotoxins in mice

BACKGROUND: Bee honey is a functional food which has a unique composition, antimicrobial properties and bifidogenic effect. In order to assess whether honey can inhibit the toxic effect of mycotoxins, the present study was undertaken. METHODS: Production of biomass and toxins by Aspergillus parasiticus and Aspergillus ochraceus were followed in media without and with honey. Although aflatoxins and ochratoxin A. were administrated to male Swiss albino mice up to 1 μg and 10 ng/kg body weight/day respectively. The experimental animals were fed diets without our with 10% honey for two months. The changes in colonic probiotic bacteria, determintal colon enzyme glucuronidases, and genotoxicity were followed. RESULTS: Addition of 32% in its media increased the biomass of A parasiticus, while the biomass of A. ochraceus decreased and Ochratoxin A. was not produced. When the honey was added at the ratio of 32 and 48% in the medium. No relationship was found between mycelium weight and production of mycotoxins. Oral administration of aflatoxins (mixture of B(1), B(2), G(1) and G(2)) and Ochratoxin A. induced structural and numerical chromosomal aberrations in bone marrow and germ cells of male mice, whereas, honey treatment reduced the genotoxicity of mycotoxins. Also both toxins induced histopathological changes in liver and kidney. Feeding on diet supplemented with honey improved the histopathological changes in case of aflatoxin group, but not in the case of ochratoxin A. group (except of kidney in two cases). No significant differences were found in the activity of colon β-glucuronidase between group fed diet with or without honey. On the other hand, the colon bifido bacteria and lactobacilli counts were increased markedly in group receiving diet supplemented with honey. CONCLUSION: Substituting sugars with honey in processed food can inhibit the harmful and genotoxic effects of mycotoxins, and improve the gut microflora

Nomograms of Iranian fetal middle cerebral artery Doppler waveforms and uniformity of their pattern with other populations' nomograms

<p>Abstract</p> <p>Background</p> <p>Doppler flow velocity waveform analysis of fetal vessels is one of the main methods for evaluating fetus health before labor. Doppler waves of middle cerebral artery (MCA) can predict most of the at risk fetuses in high risk pregnancies. In this study, we tried to obtain normal values and their nomograms during pregnancy for Doppler flow velocity indices of MCA in 20 – 40 weeks of normal pregnancies in Iranian population and compare their pattern with other countries' nomograms.</p> <p>Methods</p> <p>During present descriptive cross-sectional study, 1037 normal pregnant women with 20^th–40^thweek gestational age were underwent MCA Doppler study. All cases were studied by gray scale ultrasonography initially and Doppler of MCA afterward. Resistive Index (RI), Pulsative Index (PI), Systolic/Diastolic ratio (S/D ratio), and Peak Systolic Velocity (PSV) values of MCA were determined for all of the subjects.</p> <p>Results</p> <p>Results of present study showed that RI, PI, S/D ratio values of MCA decreased with parabolic pattern and PSV value increased with simple pattern, as gestational age progressed. These changes were statistically significant (P = 0.000 for all of indices) and more characteristic during late weeks of pregnancy.</p> <p>Conclusion</p> <p>Values of RI, PI and S/D ratio indices reduced toward the end of pregnancy, but PSV increased. Despite the trivial difference, nomograms of various Doppler indices in present study have similar pattern with other studies.</p

Crystal Structure of the Formin mDia1 in Autoinhibited Conformation

Formin proteins utilize a conserved formin homology 2 (FH2) domain to nucleate new actin filaments. In mammalian diaphanous-related formins (DRFs) the FH2 domain is inhibited through an unknown mechanism by intramolecular binding of the diaphanous autoinhibitory domain (DAD) and the diaphanous inhibitory domain (DID).Here we report the crystal structure of a complex between DID and FH2-DAD fragments of the mammalian DRF, mDia1 (mammalian diaphanous 1 also called Drf1 or p140mDia). The structure shows a tetrameric configuration (4 FH2 + 4 DID) in which the actin-binding sites on the FH2 domain are sterically occluded. However biochemical data suggest the full-length mDia1 is a dimer in solution (2 FH2 + 2 DID). Based on the crystal structure, we have generated possible dimer models and found that architectures of all of these models are incompatible with binding to actin filament but not to actin monomer. Furthermore, we show that the minimal functional monomeric unit in the FH2 domain, termed the bridge element, can be inhibited by isolated monomeric DID. NMR data on the bridge-DID system revealed that at least one of the two actin-binding sites on the bridge element is accessible to actin monomer in the inhibited state.Our findings suggest that autoinhibition in the native DRF dimer involves steric hindrance with the actin filament. Although the structure of a full-length DRF would be required for clarification of the presented models, our work here provides the first structural insights into the mechanism of the DRF autoinhibition