scholarly journals Navigation within host tissues: cues for orientation of Diplostomum spathaceum (Trematoda) in fish towards veins, head and eye

Parasitology ◽  
2007 ◽  
Vol 134 (7) ◽  
pp. 1013-1023 ◽  
Author(s):  
W. HAAS ◽  
C. WULFF ◽  
K. GRABE ◽  
V. MEYER ◽  
S. HAEBERLEIN
Keyword(s):  
Blood Vessels ◽  
Skin Surface ◽  
Chemical Concentration ◽  
Concentration Gradients ◽  
Diplostomum Spathaceum ◽  
Preliminary Model ◽  
Molecular Fraction ◽  
Arginine Residues ◽  
Fish Fins ◽  
Host Tissues

SUMMARYCercariae of Diplostomum spathaceum penetrate the skin of fish, and then migrate along blood vessels and tissues towards the head and the eye-lens. We studied their orientation behaviour in tail fins of guppies and in chemical concentration gradients within agar-filled choice chambers. In fins, they entered veins and orientated cranially, independent of the blood flow and living cells. In choice chambers, they were attracted by a small molecular fraction of fish serum, D-glucose (at 1, 10, and 1000 μm), D-mannose, D-maltotriose and Cl-ions, whereas D-glucosamine repelled them (even at 1·0 nm). Amino acids were not attractive, but arginine in tetrapeptides attracted at concentrations as low as 1 μm and melatonin at 0·4–4·3 pm. We suggest a preliminary model for the behaviour of diplostomula in fish fins and attracting (+) or repelling (−) host cues: (1) migration towards deeper skin layers and avoidance of skin surface, cues: Cl-ions (+ and −), glucose (+), glucosamine (−), light radiation (−); (2) orientation in cranial direction, cue: Cl-ions (+); (3) localization of blood vessels, cues: glucose (+), arginine-residues (+); (4) localization of the retina, cue: melatonin (+). A comparison with the navigation mechanisms of tissue-migrating schistosomules and hookworm larvae reveals an enormous diversity of strategies.

Heat Transfer to Blood Vessels

1980 ◽  
Vol 102 (2) ◽  
pp. 110-118 ◽  
Author(s):  
J. C. Chato
Keyword(s):  
Heat Transfer ◽  
Blood Vessels ◽  
Internal Heat ◽  
Absolute Magnitude ◽  
Skin Surface ◽  
Tissue Temperature ◽  
Single Vessel ◽  
Controlling Parameter ◽  
Order Of Magnitude ◽  
Linear Effects

Heat transfer to individual blood vessels has been investigated in three configurations: a single vessel, two vessels in counterflow, and a single vessel near the skin surface. For a single vessel the Graetz number is the controlling parameter. The arterioles, capillaries, and venules have very low Graetz numbers, Gz < 0.4, and act as perfect heat exchangers in which the blood quickly reaches the tissue temperature. The large arteries and veins with Graetz numbers over 103 have virtually no heat exchange with the tissue, and blood leaves them at near the entering temperature. Heat transfer between parallel vessels in counterflow is influenced most strongly by the relative distance of separation and by the mass transferred from the artery to the vein along the length. These two effects are of the same order of magnitude, whereas the film coefficients in the blood flow are of significant but lesser importance. The effect of a blood vessel on the temperature distribution of the skin directly above it and on the heat transfer to the environment increases with decreasing depth-to-radius ratio and decreasing Biot number based on radius. The absolute magnitude of these effects is independent of other linear effects, such as internal heat generation or a superimposed one-dimensional heat flux.

Bio-Inspired Active Electrolocation Sensors for Inspection of Tube Systems

2012 ◽  
Vol 84 ◽  
pp. 45-50 ◽  
Author(s):  
Martin Gottwald ◽  
Gerhard von der Emde
Keyword(s):  
Blood Vessels ◽  
Electric Fields ◽  
Skin Surface ◽  
Ring Electrode ◽  
Weakly Electric Fish ◽  
Atherosclerotic Lesions ◽  
Electric Image ◽  
Coronary Blood Vessels ◽  
Weakly Electric ◽  
Gnathonemus Petersii

At night, weakly electric fish Gnathonemus petersii use active electrolocation to scan their environment with self generated electric fields. Nearby objects distort the electric fields and are recognized as electric images on the electroreceptive skin surface of the animal. By analyzing the electric image, G. petersii can sense an object’s distance, dimensions and electrical properties. The principles and algorithms of active electrolocation can be applied to catheter-based sensor systems for analysing wall changes in fluid filled tube systems, for example atherosclerotic plaques of the coronary blood vessels. We used a basic atherosclerosis model of synthetic blood vessels and plaques, which were scanned with a ring electrode catheter applying active electrolocation. Based on the electric images of the plaques and the evaluation of bio-inspired image parameters, the plaque’s fine-structure could be assessed. Our results show that imaging through active electrolocation principally has the potential to detect and characterize atherosclerotic lesions.

scholarly journals Electrolyte Metabolism in HeLa Cells

1963 ◽  
Vol 46 (6) ◽  
pp. 1303-1315 ◽  
Author(s):  
Margaret Wickson-ginzburg ◽  
A. K. Solomon
Keyword(s):  
Transport System ◽  
Hela Cells ◽  
Generation Time ◽  
Chemical Concentration ◽  
Concentration Gradients ◽  
K Uptake ◽  
Initial Value ◽  
Electrolyte Metabolism ◽  
K Cells ◽  
Low K

Methods have been developed to study cellular Na, K, and Cl concentrations in HeLa cells. Cell [Na] and [K] are functions of the age of the culture. As the culture grows [K], expressed in mmols/liter cell H2O, rises from an initial value of 121 to a peak of 206 at about 4 days, and thereafter falls until it has almost returned to the initial value by the 9th day. [Na] falls as [K] rises, but there is no fixed relationship between the cellular concentrations of the two cations. There is, however, a correlation between generation time and cellular [K]. Measurements of net K uptake and net Na extrusion were carried out during 1 hour incubation at 37°C of low K cells. Both net K uptake and net Na extrusion took place against chemical concentration gradients, so that at least one transport system must be active; if the Cl distribution is passive both net K uptake and net Na extrusion are active. Studies with inhibitors of respiration and glycolysis lead to the conclusion that respiration is not required for these net transports, which appear to derive their energy from glycolytic sources.

Diagnosing Basal Cell Carcinoma by Dermatoscopy

1998 ◽  
Vol 3 (2) ◽  
pp. 62-67 ◽  
Author(s):  
David M. Carroll ◽  
Elizabeth M. Billingsley ◽  
Klaus F. Helm
Keyword(s):  
Basal Cell Carcinoma ◽  
Cell Carcinoma ◽  
Blood Vessels ◽  
Basal Cell ◽  
Skin Surface ◽  
Skin Lesions ◽  
Noninvasive Technique ◽  
Cutaneous Malignancy ◽  
Basal Cell Carcinomas ◽  
Pigmented Skin Lesions

Background: Dermatoscopy (DS) has been used primarily to evaluate pigmented skin lesions. Little information is available on DS findings of basal cell carcinoma (BCC). Dermatoscopy is a noninvasive technique that allows visualization of cutaneous features from the skin surface to the papillary dermis. Basal cell carcinoma, the most common cutaneous malignancy, is traditionally diagnosed clinically and confirmed with biopsy. Objective: To determine the dermatoscopic features of non-pigmented basal cell carcinomas. Methods: The dermatoscopic findings of 27 lesions that clinically were suspicious for BCC were analyzed. Results: Of these 27 clinically suspect lesions, the biopsies revealed BCC in 20 specimens and squamous cell carcinoma (SCC) in two specimens. Twenty of these 22 specimens had dermatoscopic findings of BCC: diffusely distributed, branching blood vessels, asymmetric, and narrow blood vessels distributed deeper in the dermis, or a milky-red corona with superficial wide blood vessels. One nodular BCC in our study showed no distinct findings. Conclusions: Many BCCs have characteristic DS findings; however, dermatoscopic examination of some tumours will not demonstrate any known characteristic findings. As such, the DS criteria we propose for BCC are best utilized as an adjunctive study of clinical impressions. Biopsy remains the definitive diagnostic tool.

scholarly journals A laboratory exercise using a physical model for demonstrating countercurrent heat exchange

2012 ◽  
Vol 36 (1) ◽  
pp. 58-62
Author(s):  
Catherine Loudon ◽  
Elizabeth C. Davis-Berg ◽  
Jason T. Botz
Keyword(s):  
Blood Flow ◽  
Heat Exchange ◽  
Blood Vessels ◽  
Physical Model ◽  
Circulatory System ◽  
Concentration Gradients ◽  
Laboratory Exercise ◽  
Permeable Barrier ◽  
Countercurrent Exchange ◽  
Physical Principles

A physical model was used in a laboratory exercise to teach students about countercurrent exchange mechanisms. Countercurrent exchange is the transport of heat or chemicals between fluids moving in opposite directions separated by a permeable barrier (such as blood within adjacent blood vessels flowing in opposite directions). Greater exchange of heat or chemicals between the fluids occurs when the flows are in opposite directions (countercurrent) than in the same direction (concurrent). When a vessel loops back on itself, countercurrent exchange can occur between the two arms of the loop, minimizing loss or uptake at the bend of the loop. Comprehension of the physical principles underlying countercurrent exchange helps students to understand how kidneys work and how modifications of a circulatory system can influence the movement of heat or chemicals to promote or minimize exchange and reinforces the concept that heat and chemicals move down their temperature or concentration gradients, respectively. One example of a well-documented countercurrent exchanger is the close arrangement of veins and arteries inside bird legs; therefore, the setup was arranged to mimic blood vessels inside a bird leg, using water flowing inside tubing as a physical proxy for blood flow within blood vessels.

Mass Transfer Performance of a Marine Zooplankton Olfactometer

2021 ◽  
Vol 143 (11) ◽  
Author(s):  
Ahmed A. Alkhafaji ◽  
Osama M. Selim ◽  
Ryoichi S. Amano ◽  
J. R. Strickler ◽  
P. Hinow ◽  
...  
Keyword(s):  
Host Finding ◽  
Chemical Concentration ◽  
Concentration Gradients ◽  
3 Dimensional ◽  
Marine Zooplankton ◽  
Chemical Gradients ◽  
Fluid Physics ◽  
Flow Domain ◽  
Chemical Distribution ◽  
Gnathiid Isopod

Abstract By adopting different methods to the inlet of a zooplankton olfactometer, the current study investigates the effect of the energy of chemical flow on the Gnathiid isopod crustaceans predicted behavior. These are mobile external parasites of fishes that have a significant impact on the health of their hosts. They rely at least in part on olfactory cues to find the host fish. To better understand host-finding dynamics in these parasites, a study was conducted with the simulations as a blueprint for developing a 3-dimensional test apparatus similar to what has been used for studying olfactory orientation in insects. The simulated olfactometer has four legs, each leg forming an inlet where fluids are introduced into the flow domain. There is one outlet at the center of the device. A mixture of water and chemicals is presented by applying a multi-component system. The shear and chemical concentration distribution were conducted to see how fluid physics plays a role in creating a chemical landscape. Computational results show distinct regions separated by high chemical concentration gradients when introducing chemicals from one leg. Changing the fluid inflow from one common inlet to three inlets shows that the chemical distribution exhibits steeper gradients than the typical inlet case, depicting that the gradual chemical concentrations can drive the animal toward the target faster. The best behavior that gives higher chemical gradients is obtained through the study when using three sub-inlets and Schmidt number between 3 and 10.

scholarly journals Application of an online ion-chromatography-based instrument for gradient flux measurements of speciated nitrogen and sulfur

2016 ◽  
Vol 9 (6) ◽  
pp. 2581-2592 ◽  
Author(s):  
Ian C. Rumsey ◽  
John T. Walker
Keyword(s):  
Ion Chromatography ◽  
Concentration Gradient ◽  
Sampling Site ◽  
Measurement Techniques ◽  
Ambient Air ◽  
Chemical Concentration ◽  
Concentration Gradients ◽  
Transfer Velocity ◽  
Surface Exchange ◽  
Chemical Concentration Gradient

Abstract. The dry component of total nitrogen and sulfur atmospheric deposition remains uncertain. The lack of measurements of sufficient chemical speciation and temporal extent make it difficult to develop accurate mass budgets and sufficient process level detail is not available to improve current air–surface exchange models. Over the past decade, significant advances have been made in the development of continuous air sampling measurement techniques, resulting with instruments of sufficient sensitivity and temporal resolution to directly quantify air–surface exchange of nitrogen and sulfur compounds. However, their applicability is generally restricted to only one or a few of the compounds within the deposition budget. Here, the performance of the Monitor for AeRosols and GAses in ambient air (MARGA 2S), a commercially available online ion-chromatography-based analyzer is characterized for the first time as applied for air–surface exchange measurements of HNO3, NH3, NH4+, NO3−, SO2 and SO42−. Analytical accuracy and precision are assessed under field conditions. Chemical concentrations gradient precision are determined at the same sampling site. Flux uncertainty measured by the aerodynamic gradient method is determined for a representative 3-week period in fall 2012 over a grass field. Analytical precision and chemical concentration gradient precision were found to compare favorably in comparison to previous studies. During the 3-week period, percentages of hourly chemical concentration gradients greater than the corresponding chemical concentration gradient detection limit were 86, 42, 82, 73, 74 and 69 % for NH3, NH4+, HNO3, NO3−, SO2 and SO42−, respectively. As expected, percentages were lowest for aerosol species, owing to their relatively low deposition velocities and correspondingly smaller gradients relative to gas phase species. Relative hourly median flux uncertainties were 31, 121, 42, 43, 67 and 56 % for NH3, NH4+, HNO3, NO3−, SO2 and SO42−, respectively. Flux uncertainty is dominated by uncertainty in the chemical concentrations gradients during the day but uncertainty in the chemical concentration gradients and transfer velocity are of the same order at night. Results show the instrument is sufficiently precise for flux gradient applications.

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