Casson fluid model for pulsatile flow of blood under periodic body acceleration

Pulsatile flow of a Casson fluid under the influence of a periodic body acceleration has been studied in this paper. An implicit finite difference numerical procedure has been used to analyze the flow. Applicability of this method has been checked by comparing the obtained results with the analytical solution for Newtonian flow and explicit scheme solution. The agreement between the implicit and explicit scheme solutions and the analytical solution is good (error less than 1%). Flow variables have been computed at three locations in cardiovascular system (wide (femoral) and narrow (arteriole and coronary) tubes). Effects of yield stress, tube radius and pressure gradient combined, body acceleration amplitude and frequency etc., on flow have been studied. The following observations have been made: (i) Initial transient time It changes with yield stress in narrow tubes are insignificant, whereas in wide tubes It decreases with yield stress; (ii) The axial velocity and fluid acceleration variations with yield stress are uniform (changes only quantitatively, profiles shape remain same) in narrow tubes, whereas in wide tubes these variations are non-uniform (profiles change qualitatively as well as quantitatively); (iii) Yield stress effects on wall shear amplitude are insignificant in narrow tubes (congruent to 0.3% in arteriole and congruent to 6% in femoral); and (iv) For Newtonian fluid, mean flow rate does not change with body acceleration amplitude a0 and frequency fb but it increases (decreases) with a0(fb) for Casson fluid.     

Analysis of the enzymatic activity of individual subcellular particles of Acetabularia mediterranea.

A simple procedure is described for quantitative spectrophotometric analysis of individual subcellular particles; the procedure is based upon the method proposed earlier to measure the optical density of microdroplets in capillary flow cells. The activity of malate dehydrogenase (MDH) was determined in individual chloroplasts, nuclei, nucleoli, and nuclear membranes of the unicellularalga Acetabularia. Chloroplasts are markedly heterogeneous in their enzymatic activity. A high MDH activity is characteristic of nuclei, insignificant activity is found in nuclear membranes, and no activity is present in nucleoli.     

Computational Fluid Dynamics (CFD) study of the 4th generation prototype of a continuous flow Ventricular Assist Device (VAD)

The continuous flow ventricular assist device (VAD) is a miniature centrifugal pump, fully suspended by magnetic bearings, which is being developed for implantation in humans. The CF4 model is the first actual prototype of the final design product. The overall performances of blood flow in CF4 have been simulated using computational fluid dynamics (CFD) software: CFX, which is commercially available from ANSYS Inc. The flow regions modeled in CF4 include the inlet elbow, the five-blade impeller, the clearance gap below the impeller, and the exit volute. According to different needs from patients, a wide range of flow rates and revolutions per minute (RPM) have been studied. The flow rate-pressure curves are given. The streamlines in the flow field are drawn to detect stagnation points and vortices that could lead to thrombosis. The stress is calculated in the fluid field to estimate potential hemolysis. The stress is elevated to the decreased size of the blood flow paths through the smaller pump, but is still within the safe range. The thermal study on the pump, the blood and the surrounding tissue shows the temperature rise due to magnetoelectric heat sources and thermal dissipation is insignificant. CFD simulation proved valuable to demonstrate and to improve the performance of fluid flow in the design of a small size pump.     

Membrane Filter Technique for Enumeration of Pseudomonas aeruginosa

A membrane filter procedure for the quantitation of Pseudomonas aeruginosa (mPA procedure) has been developed. Through the use of inhibitors and an elevated incubation temperature, the level of background microbial flora was decreased approximately 10,000-fold. Using P. aeruginosa cells suspended in sea water and held for 24 hr, between 70 and 100% of the „viable” cells could be recovered by the mPA procedure. Assay variability was found to be insignificant. The recoveries of P. aeruginosa from surface (fresh and salt) waters, potable waters, and sewage by the mPA procedure exceeded those obtainable by current methods. Subsequent to its development and evaluation, the mPA procedure was used at three other laboratories for the enumeration of P. aeruginosa in potable and recreational waters and in sewage samples. It was found amenable to routine use, and confirmation of typical colonies approached 100%.     

Evaluation of a rapid fractionation procedure of rabbit reticulocytes after digitonin or hypotonic hemolysis for the study of enzyme and metabolite distributions

A rapid centrifugation procedure following cell lysis with either digitonin or short hypotonic shock in EDTA containing solutions was evaluated, applicable for investigations of enzyme and metabolite compartmentations in intact rabbit reticulocytes. The application of the digitonin disruption seems to be restricted to cell suspensions containing up to 40% reticulocytes only, whereas the hypotonic lysis can be used with practically pure reticulocytes, too. The distribution of markers revealed that an almost complete cell disruption, sufficient separation into pellet and supernatant fraction and satisfactory preservation of mitochondrial intactness could be achieved under appropriate conditions. The suitability of the proposed method in studies on reticulocyte energy metabolism is further supported by the almost insignificant ATP splitting during the entire procedure.     

Nucleoside diphosphate kinase at the cell surface of neoplastic human cells in culture

Strong evidence is given that a nucleoside diphosphate kinase is present to some extent on the surface of intact neoplastic cells in culture. Experiments could be performed with cells cultured in a few plates to which an incubation medium was added. The cells were firmly attached to the supporting medium and remained viable during the incubation procedure. Determinations of lactate dehydrogenase were carried out to rule out any possible contamination from the culturing medium as well as from the cell interior. From these analyses, a procedure was developed which easily removed the last traces of the culturing medium and which showed that there was no leakage of intracellular lactate dehydrogenase during the incubation procedure. There was a rather insignificant diffusion of nucleoside diphosphate kinase into the incubation medium. In common with other nucleoside diphosphate kinases, the glioma cell surface enzyme seemed to be nonspecific with regard to nucleotide substrates.     

A proposal to improve the efficiency of index selection by “rounding”

Summary This paper describes a rounding procedure to improve the efficiency of index selection. The procedure involves performing canonical variate analysis on the phenotypic and genotypic variances of a group of traits estimated from a progeny test experiment. The eigenvectors corresponding to the significant eigenvalues are used to transform the original traits into a set of independent variables. The selection index is then constructed based on the new set of variables. The efficiency of the new index is expected to be improved by rounding off the variables associated with the insignificant eigenvalues.     

Multiscale models of the hybrid palliation for hypoplastic left heart syndrome

A less-invasive procedure that combines interventional stent placement in the ductus arteriosus and surgical banding of the branch pulmonary arteries has been recently introduced in the treatment of the hypoplastic left heart syndrome (HLHS). The hemodynamic behaviour of this hybrid approach has not been examined before in a mathematical model. In this study, a mathematical model of the hybrid procedure for HLHS is described, applying a multiscale approach that couples 3D models of the area of the surgical operation and lumped parameter models of the remaining circulation. The effects of various degrees of pulmonary banding and different stent sizes inserted in the ductus arteriosus on pulmonary-systemic flow ratio, cardiac output and oxygen delivery were assessed. Computational results suggest that balanced systemic and pulmonary blood flow and optimal systemic oxygen delivery are sensitive to the degree of pulmonary arterial banding and not to the size of the ductal stent.     

Analysis of the structure and composition of individual lipoplex particles by flow fluorometry

A flow fluorometric approach to study cationic lipoid-DNA complexes is presented. The approach uses standard flow cytometry equipment and common fluorescent dyes (BODIPY and ethidium homodimer-2) to detect both lipoid and DNA content in individual particles. In addition, a procedure that allows determination of whether or not liposomes remain intact is described. The procedure is based on monitoring the retention of a polar tracer that has been preloaded into its aqueous compartment. Sample preparation, instrument setup, data analysis, and methodological limitations are described. Applications of the procedure to cationic lipoid-DNA complexes are described, and illustrations are given for the determination of how the lipoid content, composition, and structure of individual lipoplexes in a population evolve over time, starting at about 1 min after DNA and vesicles are mixed. Analogous procedures can be applied to other heterogeneous particles and supramolecular structures.     

Evaluation of Liquid Nitrogen Storage for Preservation of Group A Streptococcal M Protein-Sensitized Sheep Red Blood Cells

Streptococcal M protein-sensitized sheep red blood cells stored in liquid nitrogen showed insignificant change in titer when tested against homologous antisera over a 6-month period. This method eliminates much of the preparation time required for the passive hemagglutination procedure and increases the reproducibility of the test.     

Treatment of coronary artery aneurysms by percutaneous sealing with bovine-pericardium-covered stents

The clinical significance of coronary artery aneurysms is briefly discussed. Until recently, surgical excision was the only treatment available. Single-case reports have documented aneurysm exclusion with vein-covered stents using 10 or 11 F. guiding catheters. This paper reports four patients with coronary artery aneurysms which were successfully excluded with the use of a novel pericardium-covered stent which is less invasive and shortens procedure time compared with the use of an autologous vein-grated stent and can be deployed using 8 F. or 9 F. guiding catheters. Short-term (five- to eight-month) clinical follow-up has been event-free in all patients, and in three patients six-month follow-up angiography has shown insignificant luminal loss.     

A potentiometric method of quantitative analysis of rifampicin

A potentiometric procedure for assay of rifampicin was developed. The procedure implies titration of rifampicin as a monofunctional acid by sodium hydroxide solution (0.1 mol/l) in 75 per cent aqueous methanol. The constant ionic strength of the solution is provided by addition of KCl until its concentration is 0.1 mol/l, the titrant concentration being 10 times higher than the antibiotic concentration in the solution. This provides a precise determination of the concentration ionization constant of the antibiotic as a monofunctional acid (pKa 7.33 +/- 0.01) and an insignificant dilution of the antibiotic solution during the titration promoting precise and reproducible results. The procedure error is 0.20 per cent. The variation coefficient is 0.27 per cent.     

Membrane Filter Procedure for Enumerating the Component Genera of the Coliform Group in Seawater

A facile, quantitative, membrane filter procedure (mC) for defining the distribution of coliform populations in seawater according to the component genera was developed. The procedure, which utilizes a series of in situ substrate tests to obviate the picking of colonies for identification, also provides an estimate of the total coliform density. When pure cultures of Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae were suspended in seawater and held at 4 C for 24 h, between 56 and 100% of the cells which grew on nutrient agar spread plates at 35 C could be recovered by the mC procedure. Confirmation as coliforms of typical colonies from natural samples was about 95%. Assay variability was found to be insignificant. The recovery of coliforms from marine waters by the mC procedure was comparable to those obtainable by current methods. Klebsiella was differentiated by the urease reaction and E. coli by its ability to form indole. The confirmation frequencies for colonies designated as Klebsiella and E. coli by the in situ tests approached 95% for the former and 98% for the latter.     

Blood flow distribution in the branches of frog mesentery arterial microvessels]

The blood flow distribution in 49 arterial branchings of the mesentery (R. temporaria) was investigated (D of the trunk = 25.7 + 0.0 mum). Linear rate was measured by the impulse digital chronometry of the intervals of the erythrocyte transit time. The geometric characteristics of the branching was determined in vivo, on photographs. An asymmetric structure of the investigated branching was shown; branch 1 had the inner initial cross-section which was 2.2 times greater than that of branch 2 and lesser turning angles (29 and 59 degrees). The blood flow in branch 1 was three times greater than the blood flow in branch 2; this was due to its greater inner initial cross-section and a higher linear rate. According to calculations, the blood flow resistance of the branch-turn was insignificant in the general blood flow resistance of branches; therefore the turning angle of the branches could not serve as an important regulator of the volume of the blood flowing in them. An experimentally revealed association between the blood flow in the branches, their radius and their turning angles is well described by equations of the "optimal" model of the vessel branching.     

Subnucleolar location of fibrillarin and variation in its levels during the cell cycle and during differentiation of plant cells

The nucleolar protein fibrillarin has been studied in onion cells; it is detected as an Mr 37,000 protein by immunoblotting using a human autoimmune serum. Quantitative immunoelectron microscopy showed that most fibrillarin is localized in the transition zone between the fibrillar center (FC) and the dense fibrillar component (DFC) as well as in the priximal zone of the DFC, where the labeling shows a gradual decrease out-ward until it reaches insignificant levels in the distal zone of the DFC. Thus, fibrillarin is not uniformly distributed throughout the DFC of plant cells. This result supports the hypothesis that the morphologically homogeneous DFC may not be uniform in function; it is also in agreement with the hypothesized vectorial flow of ribosome biogenesis through the same compartments. Data are also presented showing that the amount of fibrillarin increase when nucleolar activity increases in G2, and probably decreases when nucleolar activity decreases during differentiation.     

7-Amino-actinomycin D as a specific fluorophore for DNA content analysis by laser flow cytometry

A technique for DNA amount determination by flow cytometry based on the use of 7-amino-actinomycin D (7-amino-AMD), a fluorescent analogue of antibiotic actinomycin has been investigated, and a particular staining procedure has been developed. The procedure includes short fixation in 70% ethanol and staining for 20 min in 10(-5)M solution of 7-amino-AMD at pH7. The results of DNA content measurements are very reproducible. The histograms obtained have a coefficient of variation less than 3%. The absorption maximum of the complex of 7-amino-AMD with DNA is situated in the green spectrum region, making this stain particularly suitable for argon laser flow cytometry.     

The effect of insignificant characters on the multivariate analysis of simple patterns of geographic variation

The multivariate analysis of a set of significant characters portrays a simple geographic cline which is evident even when very few characters are used. The effect of adding insignificant characters to the set of significant characters is studied, as is the effect of replacing significant characters by insignificant characters. The former (addition) causes only a slight decline in congruence between patterns of geographic variation but the latter (replacement) causes a substantial decline in congruence. The congruence between patterns of geographic variation obtained by multivariate analysis of independent character sets is plotted against character number and gives an S-shaped relationship when insignificant or significant plus insignificant characters are used. This is distinct from the convex asymptotic curve obtained when only significant characters are used. In spite of the reduction in congruence caused by the use of insignificant characters, multivariate analysis of insignificant characters consistently revealed the 'same' geographic pattern (i.e. 'cline') as the set of significant characters. However, it required 10 times as many insignificant characters to achieve this.     

Genetic processes in rural populations of the Tomsk region (migration characteristics)]

The results of analysis of genetic and demographic structure of two village communities of Tomsk region are presented. Migration processes were shown to play important role in forming genetic structure of populations; less than 20% of inhabitants of the communities under study were born in those populations, where they live at present. These village communities are characterized by high values of gametic contribution of the populations situated outside Tomsk region, by intervillage heterogeneity of gene flow structure and by insignificant gametic exchange between the populations. The portions of heterolocal and international marriages offsprings increased from elder to younger groups of inhabitants.     

The ultrastructure of the blood vessels of Branchiostoma lanceolatum (Pallas) (Cephalochordata)

Summary The ultrastructure of the blood vessels in the caudal region of Branchiostoma is described in specimens injected with indian ink. None of the vessels have endothelial cells delimiting the luminal surface. The vessels are delimited either by dense connective tissue or by the characteristic basement lamella underneath the basal lamina of the myocoelic epithelium. It is proposed that the main blood flow in the caudal region follows different pathways depending on the activity of the animal. During swimming the muscle activity of the caudal muscles may have the effect that more blood flows from the aorta to the myoseptal plexi and is drained to the caudal vessel. In the resting animal it is possible that the blood flow through the myosepta is insignificant, and that the caudal blood flow is more or less restricted to the direct connections between the aorta and the caudal vessel: the dorsoventral anastomosis and the segmental connecting vessels.Supported by a grant from the Danish Natural Science Research Council     

Dynamics of benthic communities in the Central Depression of the Barents Sea

Based on the data collected in five marine expeditions of the Murmansk Marine Biological Institute from 2002 through 2007, the spatial and temporary variability of benthic communities in the Central Depression of the Barents Sea (licensed plot of the Shtokmanovskoe condensed gas deposit) has been analyzed. The range of quantitative characteristics and the variability of species composition of deep-water zoobenthos have been determined. The influence of an insignificant change in the collecting method on the obtained results has been examined.