A modular micro-fluidic platform for cells handling by dielectrophoresis

The physical manipulation of biological cells is of vital importance in the development of miniaturized systems for biological analyses. Dielectrophoresis (DEP) has been reported as a promising method for cell manipulation without physical contact, since it exploits the dielectric properties of cells suspended in a micro-fluidic sample, under the action of high-gradient electric fields. In view of a more extended use of DEP phenomena in lab-on-chip devices, we have worked on a silicon-based platform with microfabricated electrodes, which can offer integrated solutions for a wide variety of applications, customizable for specific user needs. The platform is composed of several functional units, organized in characterization modules for the dielectric analysis and in cell manipulation stages that can be rearranged on a single chip, depending on the target application. It, therefore, represents a complete and innovative research solution, suitable for industrial applications. The non-uniform electric field for cell manipulation is generated by micro-electrodes, patterned on the silicon substrate of micro-fluidic channels, using standard micro-fabrication techniques. Numerical and parametrical modelling using the finite element method was performed to simulate the electric field distribution, quantify the DEP force and, thus, to optimize the geometry of each functional module. In this paper, we report preliminary experimental results obtained by testing some fabricated units using Saccharomyces cerevisiae cells and sheep red blood cells. A system based on the combination of some selected modules is, finally, proposed for sorting cell subpopulations.     

CUDCP-affiliated clinical psychology student views of their science training.

Scientist-practitioner models of clinical psychology training emphasize the quality of science training that students receive, but student views on this topic have not been adequately explored. The current study reports findings of a large-scale survey distributed to 163 clinical psychology doctoral programs affiliated with CUDCP. Student representatives from 55 programs (34%) returned responses from a total of 611 students. Although this response rate was not ideal, a number of important patterns in student perspectives emerged. The overwhelming majority indicated that science training was very important to them. Overall, students reported experiencing a fairly balanced emphasis on science and clinical work, and endorsed receiving a good amount of high-quality training in science. However, discrepancies were noted in the degree to which science training in some areas is emphasized versus desired. Implications for training experiences are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mouse cerebellar granule cell differentiation: electrical activity regulates the GABAA receptor alpha 6 subunit gene

GABAA receptor alpha6 subunit gene expression marks cerebellar granule cell maturation. To study this process, we used the Deltaalpha6lacZ mouse line, which has a lacZ reporter inserted into the alpha6 gene. At early stages of postnatal cerebellar development, alpha6-lacZ expression is mosaic; expression starts at postnatal day 5 in lobules 9 and 10, and alpha6-lacZ is switched on inside-out, appearing first in the deepest postmigratory granule cells. We looked for factors regulating this expression in cell culture. Membrane depolarization correlates inversely with alpha6-lacZ expression: granule cells grown in 25 mM [K+]o for 11-15 d do not express the alpha6 gene, whereas cultures grown for the same period in 5 mM [K+]o do. This is influenced by a critical early period: culturing for >/=3 d in 25 mM [K+]o curtails the ability to induce the alpha6 gene on transfer to 5 mM [K+]o. If the cells start in 5 mM [K+]o, however, they still express the alpha6-lacZ gene in 25 mM [K+]o. In contrast to granule cells grown in 5 mM [K+]o, cells cultured in 25 mM [K+]o exhibit no action potentials, mEPSCs, or mIPSCs. In chronic 5 mM [K+]o, factors may therefore be released that induce alpha6. Blockade of ionotropic and metabotropic GABA and glutamate receptors or L-, N-, and P/Q-type Ca2+ channels did not prevent alpha6-lacZ expression, but inhibition of action potentials with tetrodotoxin blocked expression in a subpopulation of cells.     

Highly controlled gene expression using combinations of a tissue-specific promoter, recombinant adenovirus and a tetracycline-regulatable transcription factor

The arterial baroreceptor reflex system is one of the most powerful and rapidly acting mechanisms for controlling arterial pressure. The purpose of the present review is to discuss data relating sympathetic activity to the baroreflex control of arterial pressure in two different experimental models: neurogenic hypertension by sinoaortic denervation (SAD) and high-renin hypertension by total aortic ligation between the renal arteries in the rat. SAD depresses baroreflex regulation of renal sympathetic activity in both the acute and chronic phases. However, increased sympathetic activity (100%) was found only in the acute phase of sinoaortic denervation. In the chronic phase of SAD average discharge normalized but the pattern of discharges was different from that found in controls. High-renin hypertensive rats showed overactivity of the renin angiotensin system and a great depression of the baroreflexes, comparable to the depression observed in chronic sinoaortic denervated rats. However, there were no differences in the average tonic sympathetic activity or changes in the pattern of discharges in high-renin rats. We suggest that the difference in the pattern of discharges may contribute to the increase in arterial pressure lability observed in chronic sinoaortic denervated rats.     

Gas gangrene due to Clostridium septicum in a patient with an occult colonic neoplasm. A case report and review of the literature

The study included 30 IHD patients with primary hypercholesterolemia (22 males and 8 females). 18 and 12 patients have received a single daily dose of fluvastatin 20 and 40 mg, respectively, in the evening for 12 weeks. The drug effect was assessed by changes in the clinical status, lipid spectrum, transport-metabolic and absorption-secretory functions of the liver. IHD patients with hypercholesterolemia were found to have dysfunction of the hepatobiliary system. Fluvastatin treatment reduced the level of total cholesterol (Ch), LDLP Ch, triglycerides. HDLP Ch levels remained unchanged. Atherogenic lipoproteins aggregation diminished. Positive changes occurred in hepatic metabolism: bilirubin concentrations lowered, serum albumin went up, absorption-secretory function of hepatocytes normalized, hepatic mono-oxidase system activated. Fluvastatin-related hepatic damage was not reported in the course of 12-month follow-up.     

The effect of temperature and moderate electric field pre-treatment on carotenoid extraction from Heterochlorella luteoviridis

Moderate electric field (MEF) was evaluated as a pre-treatment (0–180 V) to carotenoid extraction at four different temperatures (30, 40, 50 and 60 °C) followed by a extraction step using ethanol/water as solvent (75% of ethanol, v/v). During the extraction step, samples were collected at 1, 5, 30, 40 and 50 min. Results showed that MEF allowed higher carotenoid concentration at the beginning of the extraction step at 30, 40 and 50 °C, leading to better extraction results along the extraction time. A different behaviour was observed at 60 °C probably due to the thermal effects on the cell and to carotenoids thermal degradation. The highest extraction yield, 86% of the total carotenoid content (compared to exhaustive extraction), was achieved at both 40 and 50 °C with the MEF pre-treatment, indicating that a high extraction yield can be obtained even at relatively low temperatures (40 °C).     

Hyperthyroidism and production of precocious involution in the mammary glands of lactating rats

This study investigated the influence of chronic hyperthyroidism on mammary function in lactating rats and the effects on their pups. Thyroxine-treated (10 microg per 100 g body weight per day; hyperthyroid (HT)) or vehicle-treated rats were mated 2 weeks after the start of treatment and killed with their litters on days 7, 14 and 21 of lactation. Serum concentrations of triiodothyronine (T(3)) and tetraiodothyronine (T(4)) increased in thyroxine-treated rats. In HT mothers, serum prolactin decreased on day 7 and day 14 of lactation, whereas insulin-like growth factor I (IGF-I) and progesterone concentrations decreased, and corticosterone increased on day 7 of lactation. In HT pups, T(4) concentration increased on day 7 and day 14 of lactation, whereas T(3) increased only on day 14 of lactation, and growth hormone increased on day 7 of lactation. Mammary prolactin binding sites did not vary, but there was an increase in the binding sites in the liver on day 14 of lactation in thyroxine-treated rats. In an acute suckling experiment, thyroxine-treated rats released less oxytocin, growth hormone and prolactin and excreted less milk than did control rats. Mammary casein, lactose and total lipid concentrations in thyroxine-treated rats were similar to those of control rats on day 14 of lactation. Histological studies of the mammary glands showed an increased proportion of alveoli showing reduced or no lumina and cells with condensed nuclei on day 14 and day 21 of lactation; the TdT-mediated dUTP nick-end labelling (TUNEL) test revealed an increase in apoptosis in alveolar cells on day 21 of lactation in thyroxine-treated rats. Expression of SGP-2, a gene expressed during mammary involution, increased in thyroxine-treated rats on day 14 and day 21 of lactation, whereas expression of insulin-like growth factor binding protein 5, a proapoptotic signal, was unchanged. Bcl-2, which promotes survival of mammary gland epithelial cells was unchanged, whereas expression of IGF-I, which also promotes survival of mammary gland epithelial cells, increased on day 21 of lactation in thyroxine-treated rats. These results indicate that thyroxine treatment produces some milk stasis as a result of impairments in suckling induced release of oxytocin that may initiate the first stage of mammary involution, increasing apoptosis in a gland that is otherwise actively producing and secreting milk.     

Torsional strength comparison between two assembling techniques for aluminium drill pipe to steel tool joint connection

Two techniques for assembling an aluminium drill pipe to a steel tool joint were investigated: ‘hot’ assembling and ‘cold’ assembling. During hot assembling a difference of temperature between the two parts is exploited to impose contact interferences and then to obtain a friction bond that generates torsional strength. Hot assembling is ordinarily used. The cold assembling technique is introduced here as an alternative. During cold assembling connection make up, the contact interferences are obtained by imposing an external torque. This technique requires a proper lubricating compound between the mating surfaces, in order to reduce the torque required to make up the connection. After lubricating compound curing, the coefficient of static friction rises and a high torsional strength of the connection is obtained. Full scale experimental tests were performed both on hot assembled connections and on cold assembled connections. Cold assembling showed higher torsional strength than hot assembling; moreover cold assembling does not expose the aluminium alloy to high temperature, that can be a risk for the aluminium alloy microstructure. However, the use of the compound can be a reason of cold assembling torsional strength scatter.     

New TiNiSi-type RMgAg and RMgPd with R=Ca, Yb, and MgZn2-type Ca(Mg,Ag)2 compounds

The phases CaMgAg, YbMgAg, CaMgPd, and YbMgPd were synthesized by melting the constituent metals in sealed tantalum crucibles and by annealing at 1023 K. All the samples were homogeneous, and the crystallographic analysis, which was performed by powder and singlecrystal techniques, shows that the four compounds are isotypic and belong to the orthorhombic TiNiSi type. Magnetic measurements showed that YbMgAg and YbMgPd behave like Pauli paramagnets, according to the divalency of Yb in both phases. Within the Ca-Mg-Ag system, the existence range of the MgZn₂-type phases in the Mg-rich CaMg_2−x Ag _x pseudobinary system goes from CaMg₂ to CaMg_1.6Ag_0.4. Another stability region of the MgZn₂ structure occurs around the Ag-rich composition (Ca_0.94Mg_0.06)(Ag_1.60Mg_0.40), where magnesium replaces both the Ca and Ag atoms.