Determinants of valve gating in collecting lymphatic vessels from rat mesentery

Secondary lymphatic valves are essential for minimizing backflow of lymph and are presumed to gate passively according to the instantaneous trans-valve pressure gradient. We hypothesized that valve gating is also modulated by vessel distention, which could alter leaflet stiffness and coaptation. To test this hypothesis, we devised protocols to measure the small pressure gradients required to open or close lymphatic valves and determine if the gradients varied as a function of vessel diameter. Lymphatic vessels were isolated from rat mesentery, cannulated, and pressurized using a servo-control system. Detection of valve leaflet position simultaneously with diameter and intraluminal pressure changes in two-valve segments revealed the detailed temporal relationships between these parameters during the lymphatic contraction cycle. The timing of valve movements was similar to that of cardiac valves, but only when lymphatic vessel afterload was elevated. The pressure gradients required to open or close a valve were determined in one-valve segments during slow, ramp-wise pressure elevation, either from the input or output side of the valve. Tests were conducted over a wide range of baseline pressures (and thus diameters) in passive vessels as well as in vessels with two levels of imposed tone. Surprisingly, the pressure gradient required for valve closure varied >20-fold (0.1-2.2 cmH(2)O) as a passive vessel progressively distended. Similarly, the pressure gradient required for valve opening varied sixfold with vessel distention. Finally, our functional evidence supports the concept that lymphatic muscle tone exerts an indirect effect on valve gating.     

A model of a radially expanding and contracting lymphangion

The lymphatic system is an extensive vascular network featuring valves and contractile walls that pump interstitial fluid and plasma proteins back to the main circulation. Immune function also relies on the lymphatic system's ability to transport white blood cells. Failure to drain and pump this excess fluid results in edema characterized by fluid retention and swelling of limbs. It is, therefore, important to understand the mechanisms of fluid transport and pumping of lymphatic vessels. Unfortunately, there are very few studies in this area, most of which assume Poiseuille flow conditions. In vivo observations reveal that these vessels contract strongly, with diameter changes of the order of magnitude of the diameter itself over a cycle that lasts typically 2-3s. The radial velocity of the contracting vessel is on the order of the axial fluid velocity, suggesting that modeling flow in these vessels with a Poiseuille model is inappropriate. In this paper, we describe a model of a radially expanding and contracting lymphatic vessel and investigate the validity of assuming Poiseuille flow to estimate wall shear stress, which is presumably important for lymphatic endothelial cell mechanotransduction. Three different wall motions, periodic sinusoidal, skewed sinusoidal and physiologic wall motions, were investigated with steady and unsteady parabolic inlet velocities. Despite high radial velocities resulting from the wall motion, wall shear stress values were within 4% of quasi-static Poiseuille values. Therefore, Poiseuille flow is valid for the estimation of wall shear stress for the majority of the lymphangion contractile cycle.     

Identification of extremely halophilic archaea associated with adult <Emphasis Type="Italic">Artemia urmiana</Emphasis>

The brine shrimp, Artemia is the dominant macrozooplankton present in many hypersaline environments. Artemia urmiana is the only macroscopic organism in Urmia Salt Lake (Iran), and the high salinity of the lake makes it a suitable environment for halophilic archaea too. Because of common environment for Artemia and extreme halophiles; this investigation is concentrated on studying the relationship between Artemia and halophilic archaea in Urmia Lake. In this study first the procedure of arhaea isolation was done. Then, isolated strains were sub-cultured and DNA was extracted and amplified by PCR using specific primers for amplifying archaeal 16S rRNA. The amplified archeal DNA fragments were purified, and sequenced. 16S rRNA sequences were compared to known sequences using the NCBI BLAST program. Sequences relating to Halorubrum, Haloarcula and Halobacterium species were identified in Urmia Salt Lake water and Artemia adults and the phylogenetic tree of different species was constructed. Only Halorubrum species were present in association with Artemia. They belong to Halobacteriaceae family of archeae which are isolated from different salt lakes in different parts of world and we could show their existence in adult Artemia, another organism living in hypersaline enviroments.     

Ultrafiltration of highly concentrated antibody solutions: Experiments and modeling for the effects of module and buffer conditions

Although ultrafiltration is currently used for the concentration and formulation of nearly all biotherapeutics, obtaining the very high target concentrations for monoclonal antibody products is challenging. The objective of this work was to examine the effects of the membrane module design and buffer conditions on both the filtrate flux and maximum achievable protein concentration during the ultrafiltration of highly concentrated monoclonal antibody solutions. Experimental data were obtained using both hollow fiber and screened cassettes and in the presence of specific excipients that are known to alter the solution viscosity. Data were compared with predictions of a recently developed model that accounts for the complex thermodynamic and hydrodynamic behavior in these systems, including the effects of back‐filtration arising from the large pressure drop through the module due to the high viscosity of the concentrated antibody solutions. Model calculations were in good agreement with experimental data in hollow fiber modules with very different fiber length and in screened cassettes having different screen geometries. These results provide important insights into the key factors controlling the filtrate flux and maximum achievable protein concentration during ultrafiltration of highly concentrated antibody solutions as well as a framework for the development of enhanced ultrafiltration processes for this application. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:692–701, 2016     

Delivery of Beneficial Microbes via Seed Coating for Medicinal and Aromatic Plant Production: A Critical Review

Journal of Plant Growth Regulation - Medicinal and aromatic plants (MAPs) producing a myriad of chemicals can be utilized in numerous sectors such as pharmaceutical products, feed and food...     

On a Poorly Known Rookery of Green Turtles (<Emphasis Type="Italic">Chelonia mydas</Emphasis>) Nesting at the Chabahar Beach,Northeastern Gulf of Oman

There is a poorly known rookery of green turtles (Chelonia mydas) nesting in sandy beaches of Chabahar town, northeastern Gulf of Oman, Iran.This study has been carried out to evaluate nesting activity of this small rookery in 2014 nesting season (June to October). In this study, total clutches were collected and transferred to an artificial hatchery. The peak of nesting occurred from the third parts of August to the end of September. Mean CCL was 106.3 ± 6 cm and mean CCW was 94.5 ± 5 cm. Females laid on average of 99.42 ± 47.8 eggs per clutch. The mean inter-nesting interval was 18.5 days. The observed clutch frequency was 3.4. Mean hatching success was 36.63 ± 4.1%. The incubation period was 61.07 ± 5.4 days. Nest status evaluation represented that major causes for the failure was unhatched egg with no obvious embryo followed by unhatched eggs with obvious but undeveloped embryos > unhatched eggs with developed embryos > hatched eggs but dead embryos. The results achieved in this study are a valuable contribution to cognition of the reproductive ecology of the green turtle population globally and regionally.     

DNA force-extension curve under uniaxial stretching

Single-molecule experiments indicate that a double-stranded DNA (ds‐DNA) increases in length if put under tension greater than 10 pN; beyond this point, its conformation can no longer be described using an inextensible worm-like chain model. For this purpose, a general sequence-dependent elastic model for tensions greater than 10 pN and for both single-stranded (ss) and ds‐DNA is proposed, and the effective elastic bending and torsional rigidities are determined from experiments to characterise their deformation. The key to this progress is that the bending and torsional deformations of the DNA backbones, the base-stacking interactions and the hydrogen bond force between the complementary base pairs are quantitatively considered in this model. Moreover, this simple elastic model can be used to globally fit to the abrupt B–S experimental transition data over a wide range of DNA molecule extensions. Based on this robust model, further study may be warranted on the mechanical response of ss- and ds‐DNA molecules.     

Solubilization of organic and inorganic phosphates by three highly efficient soil bacterial isolates

Screening soil samples collected from a diverse range of slightly alkaline soil types, we have isolated 22 competent phosphate solubilizing bacteria (PSB). Three isolates identified as Pantoea agglomerans strain P5, Microbacterium laevaniformans strain P7 and Pseudomonas putida strain P13 hydrolyzed inorganic and organic phosphate compounds effectively. Bacterial growth rates and phosphate solubilization activities were measured quantitatively under various environmental conditions. In general, a close association was evident between phosphate solubilizing ability and growth rate which is an indicator of active metabolism. All three PSB were able to withstand temperature as high as 42°C, high concentration of NaCl upto 5% and a wide range of initial pH from 5 to 11 while hydrolyzing phosphate compounds actively. Such criteria make these isolates superior candidates for biofertilizers that are capable of utilizing both organic and mineral phosphate substrates to release absorbable phosphate ion for plants.     

Effect of metformin and celecoxib on cytotoxicity and release of GDF‐15 from human mesenchymal stem cells in high glucose condition

Mesenchymal stem cells (MSCs) have therapeutic potential for treatment of diabetes. However, in vitro behavior of MSCs in high glucose condition as well as presence of glucose lowering agents is not fully understood. Because MSCs have an important role in tissue repair, we examined the effects of metformin and celecoxib on viability of MSCs in different glucose conditions. MSCs, from umbilical cord blood, were cultured in normoglycemic (glucose 5.5 mM), midglycemic (glucose 10 mM), and hyperglycemic (glucose 25 mM) conditions, and the cell viability was evaluated by MTT assay. The cytotoxicity and secretion of GDF‐15 were further tested in MSCs treated with metformin and celecoxib in various glucose concentrations. Our results showed that high glucose condition lowered viability of MSCs. Metformin treatment also inhibited proliferation of MSCs, but its toxicity was not changed in high glucose condition. Celecoxib induced cytotoxicity in MSCs, and the toxicity was increased in high glucose condition. Metformin and celecoxib induced release from MSCs; however, high glucose inhibited the metformin‐induced GDF‐15 release. These findings suggested that metformin did not increase the cytotoxicity of high glucose condition in MSCs. Moreover, celecoxib treatment in diabetic condition can reduce the viability of MSCs to proliferate and regenerate perhaps via change in release of GDF‐15.     

Serum IL-10 involved in morphine tolerance development during adjuvant-induced arthritis

Opioid receptors play an important role in modulation of hyperalgesia in inflamed tissues, but chronic morphine application induces such side effects as tolerance. There is near communications between cytokines and mu opioid receptor expression. This study was aimed to assess the role of serum IL-10 in morphine tolerance development during adjuvant-induced arthritis. Adjuvant arthritis (AA) was induced on day 0 by single injection of Complete Freund’s Adjuvant (CFA) into the rats’ hindpaw. Hyperalgesia, edema, and spinal mu opioid receptor (mOR) variations were assessed on 0, 7, 14, and 21 days of the study. For assessment of the morphine tolerance development, morphine effective dose (4 mg/kg) was administered from the 14th day after CFA injection and continued until the morphine post-dose paw withdrawal latency (PWL); it did not significantly differ from the baseline. For assessment of the effects of IL-10 on tolerance induction, a neutralizing dose (ND50) of anti-IL-10 was administered daily during different stages of the study. AA induction in the right hindpaw of rats resulted in unilateral inflammation and hyperalgesia within 21 days of the study. Anti-IL-10 antibody administration in the AA rats induced marked elevation of hyperalgesia compared to the AA control group. Our data also indicated that morphine effective anti-hyperalgesic dose significantly decreased in the AA rats compared to the control group, which this symptom was aligned with spinal mu opioid receptor (mOR) expression increase during AA. Moreover, there was a significant difference in morphine tolerance induction between the AA and control rats, and our results also demonstrated that IL-10 played an important role in tolerance-induction process. It can be concluded that morphine tolerance slowly progressed when administered morphine effective dose was reduced during AA chronic inflammation. On the other hand, it seems that increased level of serum IL-10 may affect morphine tolerance development during inflammation.