ARCHAEOMETRY, Issue 6 2009
A. J. SHORTLAND
The Pichvnari necropolis on the Black Sea coast of Georgia lies in an area known in the late first millennium as ,Colchis', on part of the trade route leading to the Orient. The burials of the necropolis date to the late fifth century bc and frequently contain grave goods, including extremely well-preserved polychrome glass beads and core-formed vessels. This paper presents a study of these vessels both stylistically and archaeologically and using SEM,WDS and LA,ICPMS. It reveals that the vessels have compositional differences that may point to multiple manufacturing sites. One of the vessels appears stylistically unique and may exhibit one of the earliest uses of manganese as a decolorizer. Major and minor element data for the vessels suggest that they may belong to the same ,Levantine' group as many Roman glass objects, suggesting that a source of sand on the coast of the Levant could have been used in their production. The beads clearly show glass with both natron- and plant ash-based flux with distinct rare earth compositions, showing multiple sites of production, some of which were probably either in the Middle East or the Indian subcontinent. [source]

NEOLITHIC ZOOMORPHIC VESSELS FROM EASTERN MACEDONIA, GREECE: ISSUES OF FUNCTION*

ARCHAEOMETRY, Issue 3 2009
C. MARANGOU
Five fragments of Late Neolithic clay zoomorphic vessels from northern Greece have been analysed for organic residues by gas chromatography , mass spectrometry. The results showed that the containers had been used in connection with a number of substances, in particular lower terpenoids, an oil or fat, possibly fossil fuel and in one case possibly beeswax. The paper considers likely interpretations of such combinations of materials in relation to possible functions of these symbolically enhanced artefacts. It appears that substances may have been used in the vessels because of their aromatic and/or medicinal and combustible properties, possibly in order to produce light, fragrance and/or smoke. [source]

FROM SUSA TO ANURADHAPURA: RECONSTRUCTING ASPECTS OF TRADE AND EXCHANGE IN BITUMEN-COATED CERAMIC VESSELS BETWEEN IRAN AND SRI LANKA FROM THE THIRD TO THE NINTH CENTURIES AD*

ARCHAEOMETRY, Issue 3 2008
B. STERN
In contrast with artefactual studies of long-distance trade and exchange in South Asia during the Prehistoric and Early Historic periods (Ardika et al. 1993; Gogte 1997; Krishnan and Coningham 1997; Tomber 2000; Gupta et al. 2001; Ford et al. 2005), few scientifically orientated analyses have focused on artefacts from the region's Historic period. During excavations at the ancient city of Anuradhapura, Sri Lanka, a number of buff ware ceramics with a putative organic coating on the interior were recovered (Coningham 2006). Dated stylistically to between the third and ninth centuries ad, analysis of the coatings using gas chromatography,mass spectrometry (GC,MS) and stable isotope analysis (carbon and deuterium) confirmed that the coatings are bitumen,an organic product associated with petroleum deposits. There are no known bitumen sources in Sri Lanka, and biomarker distributions and isotopic signatures suggest that the majority of the samples appear to have come from a single bitumen source near Susa in Iran. The relationship between the bitumen coatings and the vessels is discussed, and it is suggested that the coatings were used to seal permeable ceramic containers to allow them to transport liquid commodities. This study enhances our knowledge of networks of trade and exchange between Sri Lanka and western Asia during Historic times. [source]

FLUID FLOW IN DISTENSIBLE VESSELS

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 2 2009
CD Bertram
SUMMARY 1Flow in single vascular conduits is reviewed, divided into distended and deflated vessels. 2In distended vessels with pulsatile flow, wave propagation and reflection dominate the spatial and temporal distribution of pressure, determining the shape, size and relative timing of measured pressure waveforms, as well as the instantaneous pressure gradient everywhere. Considerable research has been devoted to accessing the information on pathological vascular malformations contained in reflected waves. Slow waves of contraction of vessel wall muscle, responsible for transport of oesophageal, ureteral and gut contents, have also been modelled. 3The pressure gradient in a vessel drives the flow. Flow rate can be predicted both analytically and numerically, but analytical theory is limited to idealized geometry. The complex geometry of biological system conduits necessitates computation instead. Initially limited to rigid boundaries, numerical methods now include fluid,structure interaction and can simultaneously model solute transport, thus predicting accurately the environment of the mechanosensors and chemosensors at vessel surfaces. 4Deflated vessels display all phenomena found in distended vessels, but have additional unique behaviours, especially flow rate limitation and flow-induced oscillation. Flow rate limitation is widespread in the human body and has particular diagnostic importance in respiratory investigation. Because of their liquid lining, the pulmonary airways are also characterized by important two-phase flows, where surface tension phenomena create flows and determine the patency and state of collapse of conduits. 5Apart from the vital example of phonation, sustained self-excited oscillation is largely avoided in the human body. Where it occurs in snoring, it is implicated in the pathological condition of sleep apnoea. [source]

PROTECTIVE ROLE OF A NOVEL ERYTHROCYTE-DERIVED DEPRESSING FACTOR ON BLOOD VESSELS OF RENOVASCULAR HYPERTENSIVE RATS

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 5-6 2007
Huan Pang
SUMMARY 1We have isolated a novel human erythrocyte-derived depressing factor (EDDF) that has a significant antihypertensive effect in various rat models of hypertension. The aim of the present study was to examine the mechanisms of action of EDDF on vascular function in two-kidney, one-clip (2K1C) renovascular hypertensive rats. 2The EDDF was prepared from human erythrocytes. Experiments were performed in 18 male Wistar rats. The vascular ring perfusion assay and a two-photon laser scanning fluorescence microscope (TMP) were used to evaluate the vascular contractile response. The effects of EDDF on phenylephrine (PE)- and noradrenaline (NA)-induced vascular contraction were evaluated in 2K1C hypertensive rats. The proliferation and DNA synthesis in vascular smooth muscle cells (VSMC) were determined using the [3H]-TdR (thymidine) incorporation and 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays. Flow cytometry, reverse transcription,polymerase chain reaction and western blots were used to measure cell cycle and apoptotic profiles, platelet-derived growth factor (PDGF)-A expression and the activity of extracelluar signal-regulated kinase (ERK)-1/2, as well as the expression of cyclin D1 and cyclin-dependent kinase (CDK) 4. 3At 10,5 g/mL, EDDF significantly decreased the PE- and NA-induced hypertensive vascular contraction. In addition, EDDF inhibited DNA synthesis in primary VSMC from 2K1C rats. The mRNA expression of PDGF-A in VSMC was twofold higher in 2K1C rats compared with control rats, whereas EDDF significantly inhibited the increment in PDGF-A mRNA expression. In addition, EDDF inhibited the phosphorylation of ERK1/2 and decreased the expression of cyclin D1 and CDK4; p21 (Cip1) levels were increased after treatment with EDDF. 4In conclusion, EDDF inhibits VSMC proliferation in 2K1C rats through G0/G1 cell cycle arrest. The effects may be mediated, in part, by enhanced expression of p21 (Cip1) and the inhibition of ERK1/2 phosphorylation and the expression of cyclin D1/CDK4 and PDGF-A. [source]

Letter: Tent Suture: Technique for Coverage of Exposed Vessel in the Neck

DERMATOLOGIC SURGERY, Issue 10 2007
ALI HENDI MD
No abstract is available for this article. [source]

Designing the 9th-Century-AD Vessel from Bozburun, Turkey

INTERNATIONAL JOURNAL OF NAUTICAL ARCHAEOLOGY, Issue 2 2009
Matthew Harpster
During the study of the 9th-century-AD vessel from Bozburun, Turkey, this author applied Richard Steffy's methodology which emphasizes the comprehensive deconstruction and step-by-step re-assembly of a vessel. This methodology, in turn, illuminated how the Bozburun ship was assembled and designed, and how this design process created particular components of the hull. This article discusses this design process, and how by understanding it we may also understand more about the people who made the Bozburun vessel. © 2009 The Author [source]

Angiogenesis and lymphangiogenesis in bronchial asthma

ALLERGY, Issue 8 2010
A. Detoraki
To cite this article: Detoraki A, Granata F, Staibano S, Rossi FW, Marone G, Genovese A. Angiogenesis and lymphangiogenesis in bronchial asthma. Allergy 2010; 65: 946,958. Abstract Neovascularization plays a prominent role in inflammation and tissue remodeling in several chronic inflammatory disorders. Vessel number and size, vascular surface area and vascular leakage are all increased in biopsies from patients with asthma. High levels of VEGF and other angiogenic factors have been detected in tissues and biological samples of patients with asthma and correlate with disease activity and inversely with airway hyper-responsiveness. Inflammation in the lung stimulates the growth of new blood vessels and these contribute to the airway obstruction or airway hyper-responsiveness, or both. Effector cells of inflammation (human lung mast cells, basophils, eosinophils, macrophages, etc.) are major sources of a vast array of angiogenic and lymphangiogenic factors. Inhaled corticosteroids reduce vascularity and growth factor expression and might modulate bronchial vascular remodeling in asthma. Specific antagonists to VEGF and other angiogenic factors and their receptors might help to control chronic airway inflammation and vascular remodeling and offer a novel approach for the treatment of chronic inflammatory lung disorders. [source]

LDA Velocity Measurements of High-Viscosity Fluids in Mixing Vessel with Vane Geometry Impeller

THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2007
Lidija Slemenik Perse
Abstract The object of this work was to measure the velocity field in non-Newtonian fluids inside mixing vessel. The six-bladed vane rotor used for mixing was designed from rotating vane geometry of a sensor system, commonly used for rheometrical measurements of complex fluids (Barnes and Nguyen, J. Non-Newtonian Fluid Mech. 98, 1-14 (2001); Schramm, 1994). During mixing, the viscosity was determined by measuring the torque at different impeller speeds, and compared to rheologically obtained shear dependent viscosity. The velocity field was determined by LDA measurements at twelve places inside mixing vessel. It was observed that axial and radial component of the velocity were insignificant at all measurement points. On the other hand, the results showed the periodic nature of tangential component of the velocity, which was confirmed with computer-aided visualization method. Ce travail avait pour objectif de mesurer le champ de vitesse dans des fluides non newtoniens dans un réservoir de mélange. Le rotor à six pales utilisé pour le mélange a été conçu d'après la géométrie des ailettes rotatives d'un système de senseurs, communément utilisés dans les mesures rhéométriques de fluides complexes (Barnes and Nguyen, J. Non-Newtonian Fluid Mech. 98, 1-14 (2001); Schramm, 1994). Lors du mélange, on a déterminé la viscosité en mesurant le couple à différentes vitesses de turbine, puis on l'a comparée à la viscosité de cisaillement obtenue rhéologiquement. Le champ de vitesse a été déterminé par des mesures LDA à douze positions dans le réservoir de mélange. On a observé que la composante axiale et radiale de la vitesse était négligeable pour tous les points de mesure. Par ailleurs, les résultats montrent la nature périodique de la composante tangentielle de la vitesse, ce qui est confirmé par une méthode de visualisation assistée par ordinateur. [source]

The Effects of Power Law Fluid Rheology on Coil Heat Transfer for Agitated Vessel in the Transitional Flow Regime

THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2004
Eric Ricci
Abstract A CFD model of heat transfer from power-law fluids to helical cooling coils in the transitional flow regime of a baffled tank mixed with a pitched blade turbine was developed with FluentTM. The model captured local temperature and velocity gradients. Simulations were run, varying Re, Pr, K and n. The results indicate that a Sieder-Tate type correlation, with the exponent on and the coefficient in front of the Reynolds number being a function of n, is recommended for estimating ho. Also, a new two coil bank design was found to be more efficient when 450 < Re < 650. On a développé à l'aide de FluentTM un modèle CFD de transfert de chaleur pour un serpentin hélicoïdal dans un réservoir à contrepales agité par une turbine à pales inclinées dans le régime de transition, appliqué au refroidissement de fluides de loi de puissance. Le modèle permet de déterminer la température locale et les gradients de vitesse. On a effectué des simulations en variant Re, Pr, K et n. Les résultats indiquent qu'une corrélation de type Sieder-Tate, où l'exposant et le coefficient prémultiplicateur du nombre de Reynolds sont fonction de n, est recommandée pour l'estimation de ho. On a également trouvé qu'une nouvelle conception de réservoir à deux serpentins était plus efficace lorsque 450 < Re < 650. [source]

Earthen Vessels: Hopeful Reflections on the Work and Future of Theological Schools,by Daniel O. Aleshire

DIALOG, Issue 2 2010
Jonathan P. Strandjord
No abstract is available for this article. [source]

Transesophageal and Transpharyngeal Ultrasound Demonstration of Reversed Diastolic Flow in Aortic Arch Branches and Neck Vessels in Severe Aortic Regurgitation

ECHOCARDIOGRAPHY, Issue 4 2004
Deepak Khanna M.D.
In the current study, we describe an adult patient with torrential aortic regurgitation due to an aortic dissection flap interfering with aortic cusp motion, in whom a transesophageal echocardiogram with the probe positioned in the upper esophagus and transpharyngeal ultrasound examination demonstrated prominent reversed flow throughout diastole in the left subclavian, left vertebral, left common carotid, and left internal carotid arteries. Another unique finding was the demonstration of aortic valve leaflets held in the fully opened position in diastole by the dissection flap as it prolapsed into the left ventricular outflow tract, dramatically documenting the mechanism of torrential aortic regurgitation in this patient. (ECHOCARDIOGRAPHY, Volume 21, May 2004) [source]

Ontogenetically stable hydraulic design in woody plants

FUNCTIONAL ECOLOGY, Issue 2 2006
J. S. WEITZ
Summary 1An important component of plant water transport is the design of the vascular network, including the size and shape of water-conducting elements or xylem conduits. 2For over 100 years, foresters and plant physiologists have recognized that these conduits are consistently smaller near branch tips compared with major branches and the main stem. Empirical data, however, have rarely been assembled to assess the whole-plant hydraulic architecture of woody plants as they age and grow. 3In this paper, we analyse vessels of Fraxinus americana (White Ash) within a single tree. Vessels are measured from cross-sections that span 12 m in height and 18 years' growth. 4We show that vessel radii are determined by distance from the top of the tree, as well as by stem size, independently of tree height or age. 5The qualitative form for the scaling of vessel radii agrees remarkably well with simple power laws, suggesting the existence of an ontogenetically stable hydraulic design that scales in the same manner as a tree grows in height and diameter. 6We discuss the implications of the present findings for optimal theories of hydraulic design. [source]

Successful angiographic embolization of recurrent elbow and knee joint bleeds in seven patients with severe haemophilia

HAEMOPHILIA, Issue 1 2009
R. KLAMROTH
Summary., In haemophilic joints with high-grade arthropathy, bleeds occur that do not respond to replacement therapy of the deficient coagulation factor. The reason may be pathologically reactive angiogenesis in chronic synovitis. Seven patients with severe haemophilia A or haemophilia B experienced recurrent massive bleeds of one elbow joint or knee joint in the absence of trauma. After initial application of factor VIII or IX (fVIII/fIX; 50 IU kg,1 bodyweight), there was only slow and never complete relief of symptoms. Despite intensive secondary prophylaxis maintaining the plasma level of factor concentrate at minimum 50%, new massive bleeds at the same location occurred. Vascular bleeding was suspected. Angiography of the arteries was performed via the femoral artery. Vessels identified as potential bleeding sources were embolized with embolization fluid (ONYX) in eight joints (six elbow and two knee joints). Under low-dose prophylactic treatment (15 IU fVIII or fIX per kg bodyweight for three times per week), no recurrent severe bleed unresponsive to coagulation factor replacement occurred after a mean observation time of 16 months after embolization. The consumption of factor concentrate decreased to one-third of the amount consumed before embolization. In conclusion, angiographic embolization with a non-adhesive liquid embolic agent might be considered as a promising therapeutic and coagulation factor saving option in joint bleeds not responding to replacement of coagulation factor to normal levels. [source]

Coronary Artery Stenting in Vessels with Reference Diameter < 3 MM

JOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 5 2000
ALFRIED GERMING M.D.
The study included 220 consecutive patients with coronary artery stenting. In 128 patients (60.8 ± 10.2 years, 68% men), a total of 184 stents were placed in coronary vessels with a reference diameter < 3 mm (group S). One hundred thirty-four stents were implanted in 92 patients (62.9 ± 9.8 years, 82.6% men) in vessels > 3 mm (group L). There was no significant difference according to clinical baseline characteristics. The primary end point of this retrospective study was the rate of periinterventional complications (death, stent thrombosis, myocardial infarction, urgent angioplasty, or surgical revascularization). The, secondary end point was the clinical and angiographic follow-ups (restenosis, recurrent angina, further revascularization) after 3 months. Cardiac complications occurred in group S in two (1.6%) patients, two stent thromboses with urgent angioplasty, one Q-wave and one non-Q-wave infarction. There was one (1.1%) event in group L, a stent thrombosis with Q-wave infarction and urgent angioplasty. Angiography at 3-month follow-up was performed in 148 patients. Restenosis occurred in group S in 31.8% and in group L in 21.7% (NS). Data according recurrent angina and recommended surgical revascularization did not differ between both groups. In group S, significantly more angioplasties of the stented lesion were performed (23/60 patients) compared to group L (6/88) (P = 0,015). Coronary artery stenting in vessels with a reference diameter < 3 mm can be performed without a high rate of periinterventional complications. Restenosis tends to be more frequent in the small vessel group, a higher rate of reangioplasties have to be expected. The clinical follow-up is comparable to a control group. [source]

Comparison of 1- and 2-Marker Techniques for Calculating System Magnification Factor for Angiographic Measurement of Intracranial Vessels

JOURNAL OF NEUROIMAGING, Issue 4 2005
A. A. Divani PhD
ABSTRACT Background and Purpose. Accurate estimation of an intracranial vessel size is crucial during a diagnostic or therapeutic angiography procedure. The use of 1 or 2 external markers of known size is previously proposed to manually estimate the magnification factor (MF) of an intracranial vessel. The authors evaluated the use of different external marker techniques commonly used during angiographic measurements. Methods. Forty-three intracranial vessels in 17 patients were measured using 1-and 2-marker techniques. To obtain the MF, 2 metallic markers were attached to the frontal-temporal regions. The MFs for the targeted vessels were obtained from the x-ray films by measuring the image sizes of the markers and their positions with respect to the target vessel. Results. Using a phantom, the errors resulted from (a) linear interpolation of MFs, (b) linear interpolation of inverse MFs, and (c) using the MFs of 1 marker, which were 1.23% to 2.23%, 0.8% to 1.55%, and 3.85% to 14.62%, respectively. A similar trend was observed for the measurement of cerebral arteries. Conclusion. The use of 2 markers can result in a more accurate estimation of the vessel size. The use of only 1 external marker can lead to substantial error based on the location of the target vessel. Optimizing image acquisition is also crucial for accurate determination of vessel size. [source]

Assessment of a New Model for Femoral Ultrasound-guided Central Venous Access Procedural Training: A Pilot Study

ACADEMIC EMERGENCY MEDICINE, Issue 1 2010
Michael C. Wadman MD
Abstract Objectives:, Repetitive practice with feedback in residency training is essential in the development of procedural competency. Lightly embalmed cadaver laboratories provide excellent simulation models for a variety of procedures, but to the best of our knowledge, none describe a central venous access model that includes the key psychomotor feedback elements for the procedure, namely intravascular contents that allow for determination of correct needle position by either ultrasonographic imaging and/or aspiration or vascular contents. Methods:, A cadaver was lightly embalmed using a technique that preserves tissue texture and elasticity. We then performed popliteal fossa dissections exposing the popliteal artery and vein. Vessels were ligated distally, and 14-gauge catheters were introduced into the lumen of each artery and vein. The popliteal artery and vein were then infused with 200 mL of icterine/gel and 200 mL of methylene blue/gel, respectively. Physician evaluators then performed ultrasound (US)-guided femoral central venous line placements and rated the key psychomotor elements on a five-point Likert scale. Results:, The physician evaluators reported a median of 10.5 years of clinical emergency medicine (EM) experience with an interquartile range (IQR) of 16 and a median of 10 central lines placed annually (IQR = 10). Physician evaluators rated the key psychomotor elements of the simulated procedure as follows: ultrasonographic image of vascular elements, 4 (IQR = 0); needle penetration of skin, 4.5 (IQR = 1); needle penetration of vein, 5 (IQR = 1); US image of needle penetrating vein, 4 (IQR = 2); aspiration of vein contents, 3 (IQR = 2); passage of dilator into vein, 4 (IQR = 2); insertion of central venous catheter, 5 (IQR = 1); US image of catheter insertion into vein, 5 (IQR = 1); and overall psychomotor feedback of the simulated procedure compared to the evaluators' actual patient experience, 4 (IQR = 1). Conclusions:, For the key psychomotor elements of central venous access, the lightly embalmed cadaver with intravascular water-soluble gel infusion provided a procedural model that closely simulated clinicians' experience with patients. ACADEMIC EMERGENCY MEDICINE 2010; 17:88,92 © 2009 by the Society for Academic Emergency Medicine [source]

Blood Flow in Snake Infrared Organs: Response-Induced Changes in Individual Vessels

MICROCIRCULATION, Issue 2 2007
RICHARD C. GORIS
ABSTRACT Objective: In the past the microkinetics of blood flow in the infrared pit organs of pit vipers has been studied with Doppler flowmetry using various infrared stimuli such as a human hand or soldering iron at various distances, lasers of various wavelengths, etc. Quick-acting variations in blood flow were recorded, and interpreted as a cooling mechanism for avoiding afterimage in the infrared receptors. However, the Doppler measurements provided only the summation of blood flow in a number of vessels covered by the sensing probe, but did not give data on flow in individual vessels. Methods: In the present work the authors introduced into the bloodstream of Gloydius and Trimeresurus pit vipers fluorescent microspheres labeled with fluorescein isothiocyanate (FITC) contained in a solution of FITC-dextran in physiological saline. They observed the passage of the microspheres through individual pit organ vessels with a fluorescent microscope to which was attached a high-speed video camera and image intensifier. Output of the camera was recorded before, during, and after stimulus with a 810-nm diode laser. Recording was done at 250 frames/s on high-speed video apparatus and downloaded to a hard disk. Disk files were loaded into proprietary software and particles were tracked and average velocities calculated. The data were then tested for significance by ANOVA with post hoc tests. Results: A significant (p < .05) increase in blood velocity was found at the focal point of the stimulus laser, but not anywhere removed from this point. Proximal severing of the pit sensory nerves caused degeneration of the pit receptor terminals and abolished stimulus-induced blood flow changes, but did not affect normal blood flow. Conclusions: The authors conclude that the receptors themselves are directly and locally controlling the smooth muscle elements of the blood vessels, in response to heating of the receptors by infrared radiation. They speculate that the heavy vascularization constitutes a cooling system for the radiation-encoding receptors, and further that the agent of control may be a volatile neuromediator such as nitric oxide. [source]

Flow in Lymphatic Networks: Interaction between Hepatic and Intestinal Lymph Vessels

MICROCIRCULATION, Issue 4 2001
RANDOLPH H. STEWART
ABSTRACT Objective: Lymph from both the liver and intestine flows into the cisterna chyli. We hypothesized that increasing liver lymph flow would increase cisterna chyli pressure and, thereby, decrease intestinal lymph flow, potentiating intestinal edema formation. Methods: Anesthetized dogs were instrumented to measure and manipulate portal vein pressure and cisterna chyli pressure. The effects of directly increasing portal pressure with and without directly increasing cisterna chyli pressure on intestinal wet-to-dry ratio and intestinal ascites formation rate were determined. Target values for portal and cisterna chyli pressures were determined following elevation of inferior vena caval pressure to levels seen in patients with obstructive caval disease. Results: Direct elevation of portal pressure (Pport) alone to 17.5 mm Hg caused a significant increase in intestinal wet-to-dry ratio (3.98 ± 0.24 vs. 3.40 ± 0.43) and the rate of ascites formation (0.36 ± 0.12 vs. 0.05 ± 0.03 mL/g dry wt/h). Simultaneous direct elevation of cisterna chyli pressure to 6.0 mm Hg and Pport to 17.5 mm Hg caused further increases in intestinal wet-to-dry ratio (5.52 ± 1.20) and ascites formation (0.57 ± 0.11 mL/g dry wt./h). Conclusions: Inferior vena caval hypertension increases liver lymph flow that elevates cisterna chyli pressure, which inhibits intestinal lymph flow and augments intestinal edema formation. [source]

Practical Seakeeping Performance Measures for High Speed Displacement Vessels

NAVAL ENGINEERS JOURNAL, Issue 4 2006
Dr. Kadir Sariöz
The seakeeping performance of high-speed displacement vessels is generally assessed, in a probabilistic manner, by using criteria-based measures of merit. Given a set of seakeeping criteria, these measures, such as the Percentage Time of Operation (PTO) and the Seakeeping Performance Index (SPI), could provide an assessment of the operability of the vessel in a specified sea area. The criteria-based measures are based upon the probability of exceeding specified ship motions in a sea environment particular to the vessel's mission. Given the operational area of the vessel, the percentage of time the vessel operates in a particular sea state can be determined by comparing the predicted motions to the motion limiting criteria. However, because the seakeeping criteria are used in a pass/fail manner, the criteria-based procedures give no credit for reducing motions that do not exceed criteria. This may result in misleading conclusions when the relative seakeeping performance of alternative design concepts is compared. It is shown that criteria-free measures, based upon a normalized summation of critical ship responses for a range of ship speeds and wave headings in a specified sea area, may produce more reliable results when the seakeeping performance of alternative designs are compared. This approach also has the clear advantage of not requiring a set of seakeeping criteria, which is subjective in nature. To demonstrate the effect of typical measures of merit on seakeeping performance assessment, six typical high-speed displacement vessel forms are considered in a comparative analysis. Both the criteria-free and criteria-based measures of merit are employed to compare the seakeeping performance of selected vessels. The results indicate that the choice of seakeeping performance measure of merit depends on the nature of seakeeping analysis and criteria-free measures offer a simple, practical, and realistic assessment in comparative seakeeeping studies. [source]

Bridging Mucosal Vessels Associated with Rhythmically Oscillating Blood Flow in Murine Colitis

THE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 1 2008
Aslihan Turhan
Abstract Oscillatory blood flow in the microcirculation is generally considered to be the result of cardiopulmonary influences or active vasomotion. In this report, we describe rhythmically oscillating blood flow in the bridging vessels of the mouse colon that appeared to be independent of known biological control mechanisms. Corrosion casting and scanning electron microscopy of the mouse colon demonstrated highly branched bridging vessels that connected the submucosal vessels with the mucosal plexus. Because of similar morphometric characteristics (19 ± 11 ,m vs. 28 ± 16 ,m), bridging arterioles and venules were distinguished by tracking fluorescent nanoparticles through the microcirculation using intravital fluorescence videomicroscopy. In control mice, the blood flow through the bridging vessels was typically continuous and unidirectional. In contrast, two models of chemically induced inflammation (trinitrobenzenesulfonic acid and dextran sodium sulfate) were associated with a twofold reduction in flow velocity and the prominence of rhythmically oscillating blood flow. The blood oscillation was characterized by tracking the bidirectional displacement of fluorescent nanoparticles. Space,time plots and particle tracking of the oscillating segments demonstrated an oscillation frequency between 0.2 and 5.1 cycles per second. Discrete Fourier transforms demonstrated a power spectrum composed of several base frequencies. These observations suggest that inflammation-inducible changes in blood flow patterns in the murine colon resulted in both reduced blood flow velocity and rhythmic oscillations within the bridging vessels of the mouse colon. Anat Rec, 291:74,82, 2007. © 2007 Wiley-Liss, Inc. [source]

Cephalic vascular anatomy in flamingos (Phoenicopterus ruber) based on novel vascular injection and computed tomographic imaging analyses

THE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 10 2006
Casey M. Holliday
Abstract Head vascular anatomy of the greater (or Caribbean) flamingo (Phoenicopterus ruber) is investigated and illustrated through the use of a differential contrast, dual vascular injection technique, and high-resolution X-ray computed tomography (CT), allowing arteries and veins to be differentiated radiographically. Vessels were digitally isolated with segmentation tools and reconstructed in 3D to facilitate topographical visualization of the cephalic vascular tree. Major vessels of the temporal, orbital, pharyngeal, and encephalic regions are described and illustrated, which confirm that the general pattern of avian cephalic vasculature is evolutionarily conservative. In addition to numerous arteriovenous vascular devices, a previously undescribed, large, bilateral, paralingual cavernous sinus that excavates a large bony fossa on the medial surface of the mandible was identified. Despite the otherwise conservative vascular pattern, this paralingual sinus was found only in species of flamingo and is not known otherwise in birds. The paralingual sinus remains functionally enigmatic, but a mechanical role in association with the peculiar lingual-pumping mode of feeding in flamingos is perhaps the most likely hypothesis. Anat Rec Part A, 288A:1031,1041, 2006. © 2006 Wiley-Liss, Inc. [source]

Review on Mixing Characteristics in Solid-Liquid and Solid-Liquid-Gas Reactor Vessels

THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2005
Gopal R. Kasat
Abstract Mechanically agitated reactors with single and multiple impeller systems are used in the industry for the various three-phase mixing processes such as crystallization, fermentation, and hydrogenation, etc. The paper reviews the experimental work reported in the literature along with different techniques used for the measurement of the specific quantities such as minimum or critical impeller speed for solid suspension. The work critically surveys the literature and makes specific recommendations for the use of appropriate correlations and conditions to be used for the success of such equipment. This assessment will put all the relevant literature on a common footing and will help to validate work reported earlier. Les réacteurs agités mécaniquement munis d'une seule turbine et de turbines multiples sont utilisés dans l'industrie pour divers procédés de mélange triphasiques, tels que la cristallisation, la fermentation, l'hydrogénation, etc. On examine dans cet article les travaux expérimentaux présentés dans la littérature scientifique ainsi que les différentes techniques utilisées pour la mesure de quantités spécifiques, telle la vitesse de turbine minimale ou critique pour la suspension de solides. On effectue une étude critique de la littérature scientifique et on propose des recommandations pour le choix de corrélations et conditions appropriées pour une bonne utilisation de cet équipement. Cette évaluation mettra toutes les publications pertinentes à un même niveau et aidera à valider le travail présenté antérieurement. [source]

Intra-arterial Effects of Cisplatin on Microvascular Anastomoses in the Rat Model

THE LARYNGOSCOPE, Issue 8 2002
Deepak Gurushanthaiah MD
Abstract Objective To evaluate the patency of microvascular anastomoses in arteries exposed to intra-arterial cisplatin. Study Design Animal model. Methods The common iliac artery of 15 rats was injected with 150 mg/m2 cisplatin. Five rats were injected with the same volume of saline serving as physiological controls. The ipsilateral femoral artery was transected and anastomosed using microsurgical technique within 3 to 5 days. A Doppler probe was used before and after the anastomosis to assess blood flow. The vessel was re-examined on postoperative day 5. Pulsatile blood flow and the presence or absence of a Doppler signal was recorded at this time. Vessels were harvested to include the anastomosis site and fixed for histological evaluation. The contralateral femoral artery was also harvested for comparison. Results All femoral artery anastomoses in the experimental and control arm had good, pulsatile blood flow by microscopic evaluation. No thrombosed vessels were visualized, and Doppler signals remained strong at all vessel anastomoses. Histological analysis of the vessels revealed a trend toward increased inflammatory infiltrate in the walls of the vessels treated with cisplatin. We did not appreciate a functional decrease in lumen size. Conclusions Selective catheterization intra-arterial cisplatin chemotherapy does not affect the patency of vessels following a microvascular anastomosis in the rat model. The trend toward increased inflammatory response in the vessel walls may suggest the need for closer monitoring in patients treated with intra-arterial chemotherapy. [source]

Lymphatic Vessels in Pancreatic Islets Implanted Under the Renal Capsule of Rats

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 4 2006
Ö. Källskog
Transplantation of pancreatic islets necessitates an engraftment process, including revascularization of the graft. Studies of graft vasculature have demonstrated that islets become revascularized during the first post-transplant week through an angiogenic process. If this also involves lymphatic vessels is unknown. The aim of the present study was to functionally evaluate if lymphatic vessels, which are absent in endogenous islets, form after islet transplantation. To achieve this, inbred Wistar-Furth rats were transplanted with 250 syngeneic islets under the renal capsule. Intra-vital microscopy of the graft in combination with interstitial injection of Evans Blue was performed 1 week, 1 month or 9,12 months later. In all animals studied, there was drainage through intra-graft lymphatic capillaries emptying into larger lymphatic vessels associated with the renal capsule. The number was slightly lower 1 week post-transplantation. Most of the lymphatic capillaries were present in the graft stroma, rather than interspersed among the endocrine cells. In some animals, we were able to demonstrate dye in regional lymph nodes. We conclude that unlike endogenous islets, islet grafts develop a lymphatic drainage. Its functional importance and characteristics remain to be established. However, it can be speculated that immune reactions may be facilitated by the presence of lymphatic vessels. [source]

Histological Assessment of Selected Blood Vessels of the Phocid Seals (Northern Elephant and Harbour Seals)

ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 3 2010
H. Smodlaka
Summary Phocid seals exhibit vascular adaptations that allow them to undertake prolonged deep dives. These vascular adaptations are either unique to phocids, or are modified vascular equivalents to those present in terrestrial mammals. One such adaptation, the aortic bulb, is a spherical enlargement of the ascending aorta specific to phocid seals. Its histological make-up consists of a reinforced tunica media with circular and longitudinal layers of elastic fibres. This reinforcement enables multi-axial deformation of the aortic bulb, thus complementing its function as a prominent elastic reservoir or ,windkessel'. A second adaptation, the hepatic sinus, is an asymmetrical dilation of the abdominal portion of the caudal vena cava and accompanying hepatic veins. The hepatic sinus is comprised of a relatively thin tunica media, with a scant smooth muscle component. The bulk of the sinus wall is comprised of tunica adventitia. A third vascular adaptation distinctive to the phocids is the pericardial venous plexus, composed of convoluted veins circumnavigating the perimeter of the heart. Microscopically, these veins have a thick tunica media and also contain valves. Smaller arteries, venules and distinct capillary beds are observed interspersed in-between these veins. It can be hypothesized, that in seals, certain vascular embryonic development may be arrested at an earlier embryonic stage, resulting in these unusual vascular formations. These modifications play a vital role in blood pressure regulation and distribution of oxygenated blood during prolonged deep diving. The purpose of this work was to elucidate the histological aspects of these unique vascular modifications and relate them to specific function. [source]

Macroscopic Anatomy of the Great Vessels and Structures Associated with the Heart of the Ringed Seal (Pusa hispida)

ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 3 2009
H. Smodlaka
Summary The ringed seal [Pusa (Phoca) hispida], as well as other seals, exhibits unique anatomical properties when compared to its terrestrial counterparts. In the ringed seal, the most conspicuous marine adaptation is the aortic bulb. This large dilatation of the ascending aorta is comparable to that found in other seal species and marine mammals. The branches of the ascending aorta (brachiocephalic trunk, left common carotid artery and left subclavian artery) are similar to those of higher primates and man. The peculiarities of the venous system are: three pulmonary veins, a pericardial venous plexus, a caval sphincter, a hepatic sinus with paired caudal vena cavae and a large extradural venous plexus. Generally, three common pulmonary veins (right, left and caudal) empty into the left atrium. The pericardial venous plexus lies deep to the mediastinal pericardial pleura (pleura pericardica) on the auricular (ventral) surface of the heart. The caval sphincter surrounds the caudal vena cava as it passes through the diaphragm. Caudal to the diaphragm, the vena cava is dilated (the hepatic sinus), and near the cranial extremity of the kidneys, it becomes biphid. The azygos vein is formed from the union of the right and left azygos veins at the level of the 5th thoracic vertebra. Cardiovascular physiological studies show some of these anatomical variations, especially of the venous system and the ascending aorta, to be modifications for diving. This investigation documents the large blood vessels associated with the heart and related structures in the ringed seal. [source]

Relation of microvessel density with microvascular invasion, metastasis and prognosis in renal cell carcinoma

BJU INTERNATIONAL, Issue 6 2008
Esin Yildiz
OBJECTIVE To clarify the significance of microvessel density (MVD) in a retrospective investigation the relationship between the pattern of MVD (reflecting angiogenesis), and tumour stage, grade, size, and occurrence of microvessel invasion (MVI), metastasis, and cancer-specific survival (CSS) in patients who had surgery for renal cell carcinoma (RCC). PATIENTS AND METHODS Vessels were labelled in sections of formalin-fixed, paraffin-embedded tissues from 54 RCCs by CD34 immunohistochemistry. The mean MVD, expressed as the number of vessels per 10 high-power fields (HPF, ×400) were measured for each case. In addition, all pathological slides were reviewed for the presence and absence of MVI. The prognostic value of MVD and MVI was then evaluated, and correlated with the usual prognostic variables, tumour metastasis and CSS. RESULTS In a univariate analysis of CSS, the MDV tended to be lower as stage increased from pT1 to pT3, and as grade increased from G1 to G4, although it was statistically significant only for stage (P < 0.001 and 0.050, respectively). The mean MVD was higher in 42 nonmetastatic than in 12 metastatic tumours, and in 33 tumours associated with MVI than in 21 with no MVI (P < 0.001). The mean MVD was also lower and significantly different for 28 large than 26 small tumours (P = 0.005). The survival rate of patients with tumours that were small, low-stage, of higher MVD, with no MVI and metastasis was significantly higher than that of patients with large, high-stage, low MVD, with MVI and metastatic tumours (all P < 0.001). MVI was significantly more common with a decreasing trend in MVD and the presence of metastasis (Spearman rank correlation rs = ,0.68, P = 0.01, and rs = 0.39, P = 0.01, respectively). Independent prognostic factors in a multivariate analysis were: in all patients with RCC, tumour stage (P = 0.013) and metastasis (P = 0.028); in those with low MVD, MVI (P = 0.004) and metastases (P = 0.016); in those with no MVI, stage (P = 0.020); in those with MVI, MVD (P = 0.001); in those with no metastases, stage (P = 0.045); and in those with metastases, MVD (P < 0.001). No independent predictor was identified in patients with high MVD. In patients with no metastases there was a significantly shorter median CSS time in RCCs with low MVD and with MVI (P = 0.004 for both). Similarly, patients who had grade 3,4 tumours, vs those with lower MVD and with MVI, had a significantly shorter median CSS (P = 0.020 for MVD, and 0.01 for MVI). CONCLUSIONS This study suggested that MVD in RCC was inversely associated with MVI, tumour metastasis, patient survival and tumour diameter and stage, from the usual prognostic variables, but MVD was not an independent prognostic factor in multivariate analysis for all patients with RCC. Low MVD and the presence of MVI appears to be a marker for identifying patients with an adverse prognosis. [source]

Prognostic significance of tumour angiogenesis in schistosoma-associated adenocarcinoma of the urinary bladder

BJU INTERNATIONAL, Issue 1 2002
E. El Sobky
Objective To report on tumour angiogenesis and its relationship with morphological variables and prognosis in adenocarcinoma of the urinary bladder associated with schistosomiasis. Patients and methods Fifty-five vesical adenocarcinomas were evaluated from 30 men and 25 women (mean age 47.2 years, sd 8.7, range 30,65) who were followed up after radical cystectomy and urinary diversion for a mean (sd, range) of 61 (43.5, 2.7,159.5) months. Vessels were stained immunohistochemically using an antibody to the platelet endothelial cell-adhesion molecule CD31. Microvessels were counted in active areas of angiogenesis within the tumours (at ×,250) and the microvessel density (MVD) quantified using the mean of three counts. Treatment failure was defined as death from cancer or the development of local recurrence or distant metastasis. Kaplan-Meier survival curves and Cox's proportional hazard model were used to assess survival. Results The overall 5- and 10-year survival rates were 57% and 51%, respectively. The presence of lymph node metastasis and high mean vascular density (> 26) were significantly associated with a poor prognosis. The 5-year survival for patients with negative lymph nodes was 66% while no patients with positive nodes survived for 5 years (P < 0.001); the survival was 72% for patients with a low MVD and 33% for those with a high MVD (P = 0.0016). From individual results plotted against vascularity in lymph node-negative patients, there was a significantly better outcome for those with a low MVD ( 26; P = 0.0099); this significance was maintained on multivariate analysis. However, there was no significant relationship between angiogenesis and the different clinicopathological factors apart from the grade (P = 0.03); tumour stage, grade and DNA profile had no significant effect on survival in these patients. Conclusions These findings suggest that assessing angiogenesis using the MVD provides an independent predictor of survival in patients with adenocarcinoma of the urinary bladder. [source]

Endovascular management of traumatic cervicothoracic arteriovenous fistula

BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 12 2003
D. F. du Toit
Background: This study evaluated a single-centre experience with endovascular repair of traumatic arteriovenous fistula in the cervicothoracic region. Methods: Endovascular repair of 27 traumatic cervicothoracic arteriovenous fistulas was attempted between August 1998 and December 2001. Patients with active bleeding or end-organ ischaemia were excluded. Follow-up was accomplished with clinical, duplex Doppler and arteriographic evaluation after 1 month and then every 3 months. Results: Twelve patients with a major vessel injury were treated by stent-graft placement. Vessels involved were the subclavian (eight), common carotid (three) and internal carotid (one) arteries. Subclavian artery side branches were embolized in three of the eight patients. Four patients developed early type 4 endoleaks but all resolved. Treatment with stent-grafts was ultimately successful in all 12 patients. Three patients were lost to follow-up. During mean follow-up of 21 (range 3,36) months, one of the remaining patients developed a graft stenosis. Fifteen patients with minor vessel injuries were treated with arterial embolization. Vessels embolized were subclavian artery branches (four), external carotid artery and branches (seven) and vertebral arteries (four). Successful embolization was accomplished in ten of 15 patients. Conclusion: Endovascular therapy is a promising alternative to surgery for selected patients with cervicothoracic arteriovenous fistula. Copyright © 2003 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. [source]