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PubMed1988

Hydrodynamic function of ten prosthetic heart valves in the aortic position.

The hydrodynamic function of five mechanical, four pericardial and one porcine size 23 mm aortic prosthetic valves has been analysed by measuring pressure differences, regurgitation and energy losses in our pulsatile flow test rig. St Jude Medical, Hancock pericardial and Mitral Medical pericardial valves had the lowest pressure drop. Calculations of total energy loss showed that the Bjork-Shiley monostrut had similar overall function to the above valves, while the Ionescu-Shiley Standard, Ionescu-Shiley Low Profile, Omniscience and Duromedics valves had slightly greater total energy losses. The Bjork-Shiley spherical disc and Wessex Medical porcine valve had the greatest energy losses. The function of the newer designs of pericardial valves compared well with the mechanical valves currently available.

Bioprosthesis↗
PubMed2005

Liver-targeted gene therapy by SV40-based vectors using the hydrodynamic injection method.

Efficient reconstitution of defective genes in hepatocytes could be used to treat various liver and systemic diseases through gene therapy. To explore the potential of SV40-based vectors in liver gene therapy, we constructed SV/luc, an SV40 T-antigen replacement transduction vector, that was propagated on COS and COT cells, which supply the SV40 T-antigen in trans. For liver targeting, BALB/C mice were injected via the tail vein with SV/luc stocks containing 3 x 10(6) to 10(8) transducing units in a volume of 1-2 ml. Luciferase activity was monitored with a light-detection cooled charged-coupled device (CCCD) camera, which enables continuous in vivo measurement of luc expression. The SV40 vector proved to be efficient in gene delivery to the liver, leading to long-term (> or =107 days) transgene expression in hepatocytes. Optimal results were obtained with 3 x 10(6) to 3 x 10(7) transducing units. The hydrodynamic vector delivery method caused transient liver inflammatory changes, with full recovery within days. Low levels of SV40-neutralizing antibodies were detected in the sera of treated mice; however, there was no indication of vector or transgene-specific cellular immune responses. Vectors packaged in vitro, using recombinant capsid proteins and plasmid DNA, were also effective in liver transduction. These results suggest that SV40 vectors may be useful for liver gene therapy.

Alanine Transaminase↗
PubMed2006

Blocking monoclonal antibodies specific for mouse IFN-alpha/beta receptor subunit 1 (IFNAR-1) from mice immunized by in vivo hydrodynamic transfection.

Herein we report the generation of mouse monoclonal antibodies (mAbs) specific for the IFNAR-1 subunit of the mouse interferon-alpha/beta (IFN-alpha/beta) receptor (MAR1 mAbs) that block type I IFN receptor signaling and biologic response induction in vitro and in vivo. These mAbs were generated from Ifnar1 (/) mice immunized by in vivo hydrodynamic transfection with a plasmid encoding the extracellular domain (ECD) of murine IFNAR-1. All MAR1 mAbs bound native receptor expressed on cell surfaces and immunoprecipitated IFNAR-1 from solubilized cells, and two mAbs also detected IFNAR-1 by Western blot analysis. in vitro, the mAbs prevented ligand-induced intracellular signaling and induction of a variety of type I IFN-induced biologic responses but had no effect on IFN-gamma-induced responses. The most effective in vitro blocker, MAR1-5A3, also blocked type I IFN-induced antiviral, antimicrobial, and antitumor responses in vivo. We also explored whether murine IFNAR-1 surface expression required the presence of Tyk2. In contrast to Tyk2-deficient human cell lines, comparable IFNAR-1 expression was found on primary cells derived either from wild-type or Tyk2 (/) mice. These mAbs represent much needed tools to more clearly elucidate the biochemistry, cell biology, and physiologic function of the type I IFNs and their receptor in mediating host-protective immunity and immunopathology.

Animals↗
PubMed1993

An improved mathematical model of hydrodynamical self-cleansing of pulmonary alveoli.

In the present paper we postulate a hydrodynamical mechanism of pulmonary alveoli cleansing and explain the role of the lung surfactant system in this phenomenon. Then a new, significantly refined mathematical model of the dynamics of the layer lining alveoli is derived and tested numerically in order to check theoretically whether the mechanism postulated can explain the phenomenon observed and to establish the influence of various physicochemical and physiological parameters on the rate of alveolar cleansing. The results obtained confirmed our hypothesis and two examples of the model verification were also shown.

Humans↗
PubMed2002

Wettable and unsinkable: the hydrodynamics of saccate pollen grains in relation to the pollination mechanism in the two New Zealand species of Prumnopitys Phil. (Podocarpaceae).

The pollination mechanism of most genera of the Podocarpaceae involves inverted ovules, a pollination drop and bisaccate pollen grains. Saccate grains have sometimes been referred to as 'non-wettable' due to their buoyant properties, while non-saccate pollen grains have been described as 'wettable'. The hydrodynamic properties of saccate pollen grains of seven podocarp species in five genera, Dacrydium Sol. ex G. Forst., Dacrycarpus (Endl.) de Laub., Manoao Molloy, Podocarpus L'Hér. ex Pers. and Prumnopitys Phil. have been tested in water, together with saccate and non-saccate pollen of four other conifer genera, Cedrus Trew (Pinaceae), Cephalotaxus Siebold & Zucc. ex Endl. (Cephalotaxaceae), Cupressus L. (Cupressaceae) and Phyllocladus Rich. ex Mirb. (Phyllocladaceae), and spores of three fern species and one lycopod species. All four spore types studied were non-wettable, whereas the bisaccate and trisaccate pollen types, like all other conifer pollen types, were wettable, enabling the grains to cross the surface tension barrier of water. Once past this barrier, grain behaviour was governed by presence or absence of sacci. Non-saccate and vestigially saccate grains sank, whereas saccate grains behaved like air bubbles, floating up to the highest point. In addition, the grains were observed to float in water with sacci uppermost, consistent with the suggestion that distally placed sacci serve to orientate the germinal furrow of the pollen grain towards the nucellus of an inverted ovule. Observations of pollen grains in the pollen chambers of naturally pollinated Prumnopitvs ovules confirmed this. The combination of buoyancy and wettability in saccate pollen has implications for the efficiency of the typical podocarp pollination mechanism.

Biomechanical Phenomena↗
PubMed1997

The hydrostatic and hydrodynamic volumes of polyols in aqueous solutions and their sweet taste.

The tastes and solution properties of sugar alcohols were studied in an attempt to illuminate the mechanism of sweet taste chemoreception. The SMURF method was used to measure tastetime-intensity of aqueous solutions of sugar alcohols and the results were interpreted using the Stevens power function and kinetic parameters. The apparent molar volumes, apparent specific volumes, partial molar volumes, partial specific volumes and intrinsic viscosities of the solutions were studied. Apparent molar volume reflects the size of the molecule in a hydrostatic state whereas intrinsic viscosity gives a measure of the size of the molecules in a hydrodynamic state. Generally the apparent molar volumes of the polyols are 6-13% greater than those of the parent sugars, indicating less interaction with the water structure. Apparent specific volume values can predict taste quality, and the average apparent specific volume for the sugar alcohols studied fits within the central part of the sweet range, i.e. 0.5-0.68 cm3/g, which accords with their ability to elicit a pure sweet taste response. Intensities and persistences of sweetness in the polyols followed the same trend as intrinsic viscosities.

Adult↗
PubMed2003

Inducing long-term survival with lasting anti-tumor immunity in treating B cell lymphoma by a combined dendritic cell-based and hydrodynamic plasmid-encoding IL-12 gene therapy.

In a previous study we showed that immunization with dendritic cells (DC) pulsed with idiotype (Id) fused with CD40 ligand (CD40L) could break the tolerance to Id which is expressed on B lymphoma cells and restored the responsiveness of T(h) cells, and, subsequently, induced IgG antibody response. However, this treatment had no therapeutic effect. In the present study, we found that using a hydrodynamic transfection-based technique, a high level of IL-12 production was noticed as early as 7 h after administering plasmid encoding IL-12 (pIL-12) and persisted at a detectable level for at least 9 days. In evaluating the efficacy of DC-based and/or IL-12 gene-based therapy in the treatment of 38C13 B cell lymphoma, it was found that either treatment alone was ineffective. However, a combined treatment induced 100% long-term survival. Furthermore, a long-lasting anti-tumor immunity was induced in these mice which resisted further tumor challenge at 58 days after initial inoculation. The surviving mice showed a strong IFN-gamma-producing T(h) cell response and humoral antibody response, but there were no detectable cytotoxic T lymphocytes. The antibody from the immune sera mediated a complement-dependent lysis of tumor cells that was tumor specific. Furthermore, immunization of mice with DC-based vaccine and pIL-12 treatment elicited higher levels of anti-Id IgG titer and an enhanced IgG2a response which increased the efficacy in mediating 38C13 tumor lysis. On examining the mechanism for this isotype change, we found that IFN-gamma production by CD4(+) T cells is not the only determining factor for achieving a successful therapy. DC-based treatment alone could induce the increase of IFN-gamma production, but lacked any therapeutic effect. The deciding factor appears to be the abrogation of IL-4 production that was achieved by combing with IL-12 gene therapy. Our study provides a basis for exploring the combined use of cytokines or cytokine genes in DC-based treatment for achieving effective cancer immunotherapy.

Animals↗
PubMed2006

Identification of the regulatory region of the L-type pyruvate kinase gene in mouse liver by hydrodynamics-based gene transfection.

Expression of L-type pyruvate kinase (L-PK) is upregulated in the liver by dietary carbohydrate. Previously, 3 carbohydrate/insulin response elements were identified in the 5'-flanking region of the L-PK gene up to bp -170. Studies of the 5'-flanking region beyond bp -183 in transgenic mice suggested that other regulatory elements may be present upstream of bp -183, but the positions of these elements were uncertain. In the present study, the existence of regulatory regions of the L-PK gene responding to stimulation by feeding was examined using in vivo hydrodynamics-based gene transfection (HT) in mouse liver. The firefly-luciferase (FL) gene, fused with various lengths of the 5'-flanking region of the L-PK gene, was introduced into mouse liver by HT. The mice had free access to a high-carbohydrate diet. In liver homogenate, luciferase activity of pL-PK(-1467)-FL (which included the 5'-flanking region from bp -1467 to +17), was markedly stimulated by feeding. 5'-Deletion up to bp -1065 caused only minor changes in luciferase activity, but further deletion up to bp -690 and bp -203 caused significant, gradual decreases in activity. Further analyses utilizing 5'-deletion mutants indicated the existence of positive regulatory regions that respond to stimulation by feeding between bp -1065 and -945, and between -300 and -203 on the L-PK gene. These results suggest that unidentified cis-acting DNA elements exist in the upstream region of the L-PK gene, and that HT is a useful approach for detecting regulatory regions of genes expressed in the liver.

Animals↗
PubMed1986

The stiffness of dsRNA: hydrodynamic studies on fluorescence-labelled RNA segments of bovine rotavirus.

The sedimentation coefficients of dsRNA segments of bovine rotavirus were determined in the analytical ultracentrifuge. The eleven segments were separated by preparative gel electrophoresis, and isolated by elution from gel pieces. The RNA was labelled by the intercalating fluorescent dye ethidium bromide at a ratio bound dye per base pair between 0.003 to 0.018. The analytical ultracentrifuge was equipped with a fluorescence recording optics. Sedimentation coefficients could be determined with amounts of RNA as little as 8 ng. All sedimentation coefficients were extrapolated to zero-concentration, zero-dye binding, and zero-impurities from the preparative gel electrophoresis. The hydrodynamic model of flexible cylinders was applied for the interpretation of the sedimentation coefficients. All dsRNA segments of rotavirus (663-3409 base pairs) and the dsRNA5 of cucumber mosaic virus (335 base pairs) fit the model of a "worm-like" or flexible cylinder with a persistence length of 1125 A and a hydrated diameter of 30 A. The results are compared with data from the literature on the persistence lengths of the B- and Z-forms of dsDNA and of viroids.

Animals↗
PubMed1988

An elongated model of the Xenopus laevis transcription factor IIIA-5S ribosomal RNA complex derived from neutron scattering and hydrodynamic measurements.

The precise molecular composition of the Xenopus laevis TFIIIA-5S ribosomal RNA complex (7S particle) has been established from small angle neutron and dynamic light scattering. The molecular weight of the particle was found to be 95,700 +/- 10,000 and 86,700 +/- 9000 daltons from these two methods respectively. The observed match point of 54.4% D2O obtained from contrast variation experiments indicates a 1:1 molar ratio. It is concluded that only a single molecule of TFIIIA, a zinc-finger protein, and of 5S RNA are present in this complex. At high neutron scattering contrast radius of gyration of 42.3 +/- 2 A was found for the 7S particle. In addition a diffusion coefficient of 4.4 x 10(-11) [m2 s-1] and a sedimentation coefficient of 6.2S were determined. The hydrodynamic radius obtained for the 7S particle is 48 +/- 5 A. A simple elongated cylindrical model with dimensions of 140 A length and 59 A diameter is compatible with the neutron results. A globular model can be excluded by the shallow nature of the neutron scattering curves. It is proposed that the observed difference of 15 A in length between the 7S particle and isolated 5S RNA most likely indicates that part(s) of the protein protrudes from the end(s) of the RNA molecule. There is no biochemical evidence for any gross alteration in 5S RNA conformation upon binding to TFIIIA.

Animals↗
PubMed1998

Quantitative analysis of polymerase chain reaction using anisotropy ratio and relative hydrodynamic volume of fluorescence polarization method.

The method based on the combination of polymerase chain reaction (PCR) and fluorescence polarization is presented. A targeted DNA was amplified with a 5'-fluorescein labeled primer, using a 256 bp DNA fragment of stx2 gene in Escherichia coli O157:H7 (188-443 bp) as a template. The fluorescence anisotropy of the 5'-fluorescein labeled primer increased upon the polymerization through Taq polymerase. The conversion of primer to PCR product was quantitatively monitored by anisotropy ratio and relative hydrodynamic volume. This system was also applied to the determination of E.coli O157:H7.

Bacterial Toxins↗
PubMed1982

Nanosecond fluorometric investigation of hydrodynamic properties of adenosine triphosphatase from thermophilic bacterium PS3.

The soluble portion (TF1) of proton-translocating ATPase from thermophilic bacterium PS3 was labeled with a fluorescent dye N-(1-pyrene)maleimide. The decay of fluorescence anisotropy of the adduct showed that TF1 in aqueous solution was characterized by a volume of equivalent sphere of 1,120 nm3. This value is 2.4 times the volume calculated from the molecular weight and partial specific volume, indicating a non-spherical shape and/or extensive hydration. A prolate ellipsoid with an axial ratio of 2 to 3 is suggested as a first approximation of the shape of hydrated TF1. The presence or absence of ATP, ADP, or Mg2+ did not alter the volume of the equivalent sphere appreciably; the probable conformational change of TF1 induced by these ligands does not lead to a gross alteration of its hydrodynamic properties.

Adenosine Triphosphatases↗
PubMed2003

Penetration of surface-inoculated bacteria as a result of electrically generated hydrodynamic shock wave treatment of boneless skinless chicken breasts.

The top surface of boneless skinless chicken breasts was inoculated with either green fluorescent protein (GFP)-labeled Escherichia coli (E. coli-GFP) or rifampicin-resistant E. coli (E. coli-Rif) and subjected to electrically generated hydrodynamic shock wave treatment (HVADH). Cryostat sampling in concert with laser scanning confocal microscopy or plating onto antibiotic selective agar was used to determine if HVADH treatment resulted in the movement of the inoculated bacteria from the outer inoculated surface to the interior of intact boneless skinless chicken breasts. In HVADH-treated boneless skinless chicken breasts, marker bacteria were detected within the first 200 microm below the inoculated surface, 50 to 100 microm beyond the depth of untreated surface inoculated boneless skinless chicken breasts. The exact depth at which the marker bacteria were found was dependent on the cryostat sampling distance used. These results suggest that HVADH treatments affect the movement of surface bacteria.

Animals↗
PubMed1996

Development of an atmospheric 222Rn concentration model using a hydrodynamic meteorological model: I. One-dimensional practical model.

A one-dimensional numerical model for 222Rn transport in an atmospheric boundary layer was developed. The model consists of two parts: a prognostic hydrodynamic model including a turbulence closure model and an atmospheric diffusion model for 222Rn. The first part predicts meteorological conditions to provide the second part with vertical turbulence conditions which affects the vertical motion of 222Rn near the Earth's surface. Calculations with the model are compared with 222Rn concentrations measured during a variety of meteorological conditions, from clear days with high radiation and low winds to cloudy days of low radiation with high winds. The model's results represent well the typical diurnal variations of the 222Rn concentrations.

Air Pollutants, Radioactive↗
PubMed1996

Development of an atmospheric 222Rn concentration model using a hydrodynamic meteorological model: II. Three-dimensional research-purpose model.

This paper describes a new type of three-dimensional numerical model for 222Rn transport in an atmospheric boundary layer. The model is a combination of a prognostic hydrodynamic meteorological model including a turbulence closure model and an atmospheric diffusion model for 222Rn. The first part provides the second part with the meteorological conditions needed for calculations of the 222Rn transport and diffusion. The model is capable of giving consideration to horizontal source distribution, complex terrain, and non-uniform and non-steady atmosphere. The model's results were compared with 222Rn field measurements in a mountain-valley area and represented qualitatively a typical diurnal variation of the 222Rn concentration in nocturnal drainage flows. The model was also applied to the transport of 222Rn in a seacoast area. These results indicated that the model could be effective as a research tool for numerical analysis of 222Rn behavior under various atmospheric conditions.

Air Pollutants, Radioactive↗
PubMed2004

Partial nephrectomy with fibrin glue repair: measurement of vascular and pelvicaliceal hydrodynamic bond integrity in a live and abbatoir porcine model.

PURPOSE: Some of the challenges during partial nephrectomy include control of bleeding and repair of the pelvicaliceal system. Fibrin tissue sealants have recently been used to achieve hemostasis and collecting system closure in open and laparoscopic partial nephrectomy. However, there exist little data regarding the intrinsic strength of the bond, especially when applied to the vasculature and the urinary collecting system of the transected kidney. We examined the hydrodynamic bond integrity of a commercially available fibrin tissue sealant in a live porcine animal model undergoing partial nephrectomy. MATERIALS AND METHODS: Open partial nephrectomy was performed in 19 porcine renal units. Collecting system entry was confirmed by methylene blue instillation into the proximal ureter. Fibrin tissue sealant was used to repair 16 renal units, that is 8 kidneys hardened in vivo for 10 minutes and 8 hardened in vivo for 60 minutes. In an additional 3 renal units monopolar electrocautery was used to achieve hemostasis (no fibrin glue used). The strength of vasculature repair was performed by infusing saline into the renal artery (renal vein ligated) and measuring pressure at bond rupture. Similarly the integrity of pelvicaliceal repair was evaluated by retrograde infusion of saline into the collecting system via the proximal ureter and measurement of pressure at bond rupture. RESULTS: Fibrin tissue sealant was successful in achieving prompt hemostasis and it was subjectively superior to cautery alone with regard to bleeding control. Mean renal vascular and pelvicaliceal burst pressure for fibrin sealant treated kidneys was 378 (median 420) and 166 mm Hg (median 170), respectively. There was no significant difference in 10 vs 60-minute hardening times in treated kidneys. In comparison, vascular and pelvicaliceal burst pressure for nontreated (cautery alone) kidneys was 230 (median 220) and 87 mm Hg (median 90), respectively. CONCLUSIONS: Commercially available fibrin tissue sealants can provide supraphysiological renal parenchyma and collecting system sealing pressures after partial nephrectomy. This information supports the potential use of fibrin sealants during open and laparoscopic partial nephrectomy.

Abattoirs↗
PubMedDate not supplied

Hydrodynamic and static performance evaluation of the moving-actuator type biventricular assist device, AnyHeart.

This study evaluated the hydrodynamic characteristics and efficiency of the moving-actuator type implantable biventricular assist device (BVAD), AnyHeart. A blood analog made of 52% glycerin and 48% water was used to simulate the density and viscosity of blood. The maximum pump flow was 9 L/min with 28.8 watts of power input, and the maximum electrical-to-hydraulic power conversion efficiency was approximately 11% at a pump flow of 3.5 L/min. The pump was able to generate 4 L/min output against 100 mm Hg afterload with less than 9 watts of power input. In addition to the overall system efficiency, the inner subpart power conversion efficiency was also evaluated. The system was subdivided according to system mechanism into three major parts: motor part, actuator part, and blood sac part. In normal working conditions (4 L/min, 100 mm Hg) with the AnyHeart, the total system efficiency was 8%, with subpart efficiencies of 50%, 85%, and 19% for motor part, actuator part, and blood sac part, respectively. The pump performance assessed in the in vitro Donovan-type mock circulation loop test was acceptable as a BVAD in terms of flow and pressure.

Blood Viscosity↗
PubMedDate not supplied

Numerical investigation on hydrodynamics and biocompatibility of a magnetically suspended axial blood pump.

A newly designed magnetically suspended axial blood pump is presented, in which a 5 degrees-of-freedom rotor is suspended by using two conical active magnetic bearings, each with a four-pole stator. The preferred configuration could provide a rather large moment of inertia to increase the rotating stability of the suspended rotor in the pump. The hydrodynamic performance and internal flow fields in the pump are investigated by computational fluid dynamics. The pump head flow characteristics and the efficiency-Q curves at various rotating speeds are obtained, and the detailed flow fields in the pump are determined numerically. The distribution of shear stress, including Reynolds shear stress, is studied and discussed. Also, special attention is given to the small clearance between the rotor and the pump shell where the reversed secondary flow is formed and can flush out the clearance to avoid the flow stagnations. The secondary flow as well as the magnetic bearings can reduce thrombus in the pump. To check the biocompatibility of the pump further, the hemolysis indexes of the pump are estimated on the basis of the computed results.

Blood Pressure↗