Normal Viscosity Research Articles

Improvement of Sperm Quality in Hyperviscous Semen following DNase I Treatment.

Semen hyperviscosity impairs sperm motility and can lead to male infertility. This prospective study aimed at assessing the ability of exogenous DNase in improving sperm quality, taking into consideration that DNase has been found in the seminal plasma of several species and that neutrophils release chromatin in order to trap bacteria. A total of seventy-seven semen samples with high seminal viscosity (HSV) as the study group and sixty-two semen samples with normal seminal viscosity (NSV) as the control group were compared in this analysis. These semen samples were divided into three groups of receiving treatment (a) with DNase I at 37°C for 15 min, (b) by density gradient centrifugation, and (c) with a combination of the above two methods. Following a fifteen-minute treatment of hyperviscous semen, the motility of spermatozoa in 83% of semen samples increased to a statistically significant degree. On the contrary, DNase treatment of semen with normal viscosity had no such effects. The above treatment was also accompanied by a significant increase in the percentage of normal spermatozoa, resulting in a major decrease of the teratozoospermia index. Comparison between semen samples that underwent density gradient centrifugation following DNase I treatment, to those collected after density gradient treatment alone, showed that in the first case the results were more spectacular. The evaluation of each preparation in terms of yield (% total progressively motile sperm count after treatment in relation to the initial total sperm count) revealed that the combined approach resulted in 29.8% vs. 18.5% with density treatment alone (p=0.0121). DNase I treatment results in an improvement of sperm motility and morphology and could be beneficial to men with hyperviscous semen in assisted reproduction protocols.

Conformational and rheological properties of a quaternary ammonium salt of curdlan

This study investigated the chain conformation, microstructure, and rheological properties of a quaternary ammonium salt of curdlan (Qcurd) in aqueous medium. Results showed that Qcurd exhibited typical polyelectrolyte behavior in pure water, and the normal viscosity character was observed in 0.1 M NaCl aqueous solution. The weight-average molecular weight (Mw), z-average radius of gyration (Rg), hydrodynamic radius (Rh), conformational parameter (α), characteristic constant (a) and structure parameter (ρ) for Qcurd were determined as 8.08 × 104 g/mol, 26.7 nm, 15.0 nm, 0.54, 0.62, and 1.78, respectively, indicating that Qcurd existed as a flexible chain conformation in 0.1 M NaCl solution, verified by atomic force microscopy. Qcurd exhibited more pronounced shear-thinning behavior at higher concentrations. The flow behavior of Qcurd at different concentrations and temperature was well evaluated by power-law model and Arrhenius equation. Dynamic tests revealed that Qcurd showed oscillatory behaviors between a dilute solution and a weak elastic gel.

Asymptotic expansion and Padé approximants for acceleration-driven Poiseuille flow of a rarefied gas: Bulk hydrodynamics and rheology.

The perturbation expansion technique is employed to solve the Boltzmann equation for the acceleration-driven steady Poiseuille flow of a dilute molecular gas flowing through a planar channel. Neglecting wall effects and focusing only on the bulk hydrodynamics and rheology, the perturbation solution is sought around the channel centerline in powers of the strength of acceleration. To make analytical progress, the collision term has been approximated by the Bhatnagar-Gross-Krook kinetic model for hard spheres, and the related problem for Maxwell molecules was analyzed previously by Tij and Santos [J. Stat. Phys. 76, 1399 (1994)JSTPBS0022-471510.1007/BF02187068]. The analytical expressions for hydrodynamic (velocity, temperature, and pressure) and rheological fields (normal stress differences, shear viscosity, and heat flux) are obtained by retaining terms up to tenth order in acceleration, with one aim of the present work being to understand the convergence properties of the underlying perturbation series solutions. In addition, various rarefaction effects (e.g., the bimodal shape of the temperature profile, nonuniform pressure profile, normal-stress differences, and tangential heat flux) are also critically analyzed in the Poiseuille flow as functions of the local Froude number. The hydrodynamic and rheological fields evaluated at the channel centerline confirmed the oscillatory nature of the present series solutions (when terms of increasing order are sequentially included), signaling the well-known pitfalls of asymptotic expansion. The Padé approximation technique is subsequently applied to check the region of convergence of each series solution. It is found that the diagonal Padé approximants for rheological fields agree qualitatively with previous simulation data on acceleration-driven rarefied Poiseuille flow.

Butane dihedral angle dynamics in water is dominated by internal friction

The dihedral dynamics of butane in water is known to be rather insensitive to the water viscosity; possible explanations for this involve inertial effects or Kramers' turnover, the finite memory time of friction, and the presence of so-called internal friction. To disentangle these factors, we introduce a method to directly extract the friction memory function from unconstrained simulations in the presence of an arbitrary free-energy landscape. By analysis of the dihedral friction in butane for varying water viscosity, we demonstrate the existence of an internal friction contribution that does not scale linearly with water viscosity. At normal water viscosity, the internal friction turns out to be eight times larger than the solvent friction and thus completely dominates the effective friction. By comparison with simulations of a constrained butane molecule that has the dihedral as the only degree of freedom, we show that internal friction comes from the six additional degrees of freedom in unconstrained butane that are orthogonal to the dihedral angle reaction coordinate. While the insensitivity of butane's dihedral dynamics to water viscosity is solely due to the presence of internal friction, inertial effects nevertheless crucially influence the resultant transition rates. In contrast, non-Markovian effects due to the finite memory time are present but do not significantly influence the dihedral barrier-crossing rate of butane. These results not only settle the character of dihedral dynamics in small solvated molecular systems such as butane, they also have important implications for the folding of polymers and proteins.

Internal Viscosity-Dependent Margination of Red Blood Cells in Microfluidic Channels.

Cytoplasmic viscosity-dependent margination of red blood cells (RBC) for flow inside microchannels was studied using numerical simulations, and the results were verified with microfluidic experiments. Wide range of suspension volume fractions or hematocrits was considered in this study. Lattice Boltzmann method for fluid-phase coupled with spectrin-link method for RBC membrane deformation was used for accurate analysis of cell margination. RBC margination behavior shows strong dependence on the internal viscosity of the RBCs. At equilibrium, RBCs with higher internal viscosity marginate closer to the channel wall and the RBCs with normal internal viscosity migrate to the central core of the channel. Same margination pattern has been verified through experiments conducted with straight channel microfluidic devices. Segregation between RBCs of different internal viscosity is enhanced as the shear rate and the hematocrit increases. Stronger separation between normal RBCs and RBCs with high internal viscosity is obtained as the width of a high aspect ratio channel is reduced. Overall, the margination behavior of RBCs with different internal viscosities resembles with the margination behavior of RBCs with different levels of deformability. Observations from this work will be useful in designing microfluidic devices for separating the subpopulations of RBCs with different levels of deformability that appear in many hematologic diseases such as sickle cell disease (SCD), malaria, or cancer.

A luminescent bimetallic iridium(iii) complex for ratiometric tracking intracellular viscosity.

A luminescent bimetallic iridium probe C10 was developed through a long soft carbon chain linkage to achieve ratiometric detection of viscosity. C10 features high sensitivity and selectivity for viscosity. More importantly, C10 is living cell permeable and can be employed to distinguish cancer cells from normal cells and track viscosity changes during MCF-7 cell apoptosis.

Influence of Ink Viscosity Level on Tone Value Increase in Sheet-Fed Offset Printing

Purpose - Dot gain is caused by ink spreading around halftone dots. Several factors can contribute to the increase in halftone dot area. As printing pressure can squeeze the ink out of its dot shape causing gain, ink viscosity is a contributing factor with coated papers, higher viscosity inks can resist the pressure better than lowest viscosity ink. Halftone dots can also be surrounded by a small circumference of ink. Each halftone dot has a microscopic relief, and ink will fall off the edge before being eliminated entirely by the fountain solution in the case of sheet-fed offset printing. The lithographic inks behavior necessitates viscosity measurement over the full range of shear rates that inks can encounter in use, this range is very wide since very low shear rates are encountered in removing ink from the can and in the ink duct, whereas exceedingly high rates of shear exist in the roller nips of fast running presses. The aim of this research is to determine the influence of the different ink viscosity levels on tone value increase of final prints in sheet-fed offset printing. Design/Methodology/Approach - Three different ink viscosity levels were used with each inking system on each printing unit, to examine tone value increase (dot gain) for sheet-fed offset printing process, measured on matte-coated paper prints. The analysis of tone values results in order to determine their dependency on ink viscosity level and which viscosity level generates the best print reproduction for the tone values. Findings - Applied ink viscosity levels influenced tone value, as well as that there was no clear trends of how print quality degrades or improve with the same ink viscosity change for tone value. Obtained mechanical dot gain values on the plates show that all tone values are reproduced correctly, without bigger increases. Taking into account ISO 12647-2:2004 standard, and reference TVI values for the prints, the most appropriate TVI values were achieved by using different ink viscosity levels for different inks, low ink viscosity level produced the best TVI values for magenta ink, normal ink viscosity level showed as a best option for cyan and yellow inks, while high ink viscosity level generated the best results for black ink.

Analysis of MYO-Inositol effect on spermatozoa motility, in hyper viscous ejaculates and in patients with grades II and III varicocele.

The goal of this study is to evaluate MYOInositol effects on spermatozoa motility, in patients' ejaculates with severe varicocele or hyper viscosity. The study included normal viscosity ejaculate from 30 patients affected by varicocele and hyper viscosity ejaculate from 33 patients without any testicular pathologies. All selected samples showed sperm concentration > 2 million/ml and progressive motility < 32%. In both groups, the pellet obtained after centrifugation in buffered medium, was divided in two aliquots, both incubated for 15 minutes at 37°C: one with MYO-Inositol and the other one, as control, only in phosphate buffered saline (PBS). Afterwards, the sperm progressive motility was assessed using Computer Assisted Sperm Analysis (CASA system). Incubation with MYO-Inositol improved sperm progressive motility in high viscosity samples compared to control group (38.9% ± 3.0 vs 24.35% ± 2.41, respectively; p ≤ 0.0001). Conversely, no statistically significant difference was observed in total sperm progressive motility in varicocele samples compared with control group (22.7% ± 2.07 vs 26.7% ± 3.31, respectively; p = 0.085). The MYO-Inositol positive effect on spermatozoa motility may depend on the type of sperm damage: heavy structural and biochemical defects which typically affects patients with varicocele are not restored by Inositol. On the contrary, MYOInositol is able to improve sperm motility in semen samples with high viscosity, since those samples show no substantial structural sperm defects.

Elucidating the flow-microstructure coupling in entangled polymer melts. Part II: Molecular mechanism of shear banding

In this study, we have elucidated the molecular origin of shear banding in the entangled polymeric melts. Specifically, it is shown that the inflection point corresponding to the stress-overshoot indicates the possibility of inhomogeneity and this combined with slow orientation relaxation in step-strain start-up experiments will lead to formation of local inhomogeneity along the velocity gradient direction. Once the aforementioned inhomogeneities are created, a localized jump in entanglement density and a commensurate jump in normal stress and viscosity will lead to formation of the incipient shear banded flow structure. To this end, number of step-strain and start-up simulations with different deformation rate ramp times in the planar Couette flow with entanglement densities ⟨Zk⟩ ≥ 17 were performed to demonstrate the effect of deformation rate ramp time on the formation of local inhomogeneities and occurrence of shear banding. It has been demonstrated that if the time scale for the deformation rate to reach its steady value is larger or on the order of the orientation relaxation time of the chain, local inhomogeneities in the velocity gradient direction will not form and the linear velocity profile will prevail. Overall, the molecular mechanism of incipient shear banding as well as its evolution to steady shear banding or to a linear velocity profile (transient shear banding) is described for the first time. Moreover, our findings are in agreement with a host of prior step-strain and start-up experiments with synthetic and natural Deoxyribonucleic acid (DNA) entangled polymeric fluids.In this study, we have elucidated the molecular origin of shear banding in the entangled polymeric melts. Specifically, it is shown that the inflection point corresponding to the stress-overshoot indicates the possibility of inhomogeneity and this combined with slow orientation relaxation in step-strain start-up experiments will lead to formation of local inhomogeneity along the velocity gradient direction. Once the aforementioned inhomogeneities are created, a localized jump in entanglement density and a commensurate jump in normal stress and viscosity will lead to formation of the incipient shear banded flow structure. To this end, number of step-strain and start-up simulations with different deformation rate ramp times in the planar Couette flow with entanglement densities ⟨Zk⟩ ≥ 17 were performed to demonstrate the effect of deformation rate ramp time on the formation of local inhomogeneities and occurrence of shear banding. It has been demonstrated that if the time scale for the deformation rate to r...

Iodide Residues in Milk Vary between Iodine-Based Teat Disinfectants.

Majority of iodine found in dairy milk comes from the diet and teat disinfection products used during milking process. The objective of this study was to evaluate the effects of 4 iodine-based teat dips on milk iodide concentrations varying in iodine level (0.25% vs. 0.5%, w/w), normal low viscosity dip versus barrier dip, and application method (dip vs. spray) to ensure safe iodine levels in dairy milk when these products are used. The iodine exposure study was performed during a 2-wk period. The trial farm was purged of all iodine-based disinfection products for 21 d during a prestudy "washout period," which resulted in baseline milk iodide range of 145 to 182 ppb. During the experiment, iodine-based teat dips were used as post-milking teat disinfectants and compared to a non-iodine control disinfectant. Milk iodide residue levels for each treatment was evaluated from composited group samples. Introduction of different iodine-based teat disinfectants increased iodide residue content in milk relative to the control by between 8 and 29 μg/L when averaged across the full trial period. However, residues levels for any treatment remained well below the consumable limit of 500 μg/L. The 0.5% iodine disinfectant increased milk iodide levels by 20 μg/L more compared to the 0.25% iodine. Compared to dip-cup application, spray application significantly increased milk iodide residue by 21 μg/L and utilized approximately 23% more teat dip. This carefully controlled study demonstrated an increase in milk iodide concentrations from iodine disinfectants, but increases were small and within acceptable limits.

Safety Appraisal of Lithium Bis(fluorosulfonyl) Imide (LiFSI) As Electrolyte Salt for Li-Ion Batteries

The success of Li-ion batteries technology relies on a careful evaluation of its safety and subsequently an ad hoc choice of battery key components such as electrolyte salts and solvents, which play a crucial role with respect to safety [1] and proper battery functioning, stabilizing interfacial reactions. The standard electrolyte consists of LiPF6 salt dissolved in carbonates solvents. Thermal instability, moisture sensitivity, and release of HF via hydrolysis of PF6 with protic species suggest a priority for the replacement of LiPF6 with new solutes with improved thermal, chemical and/or electrochemical properties. Thereby, over the past two decades, great efforts have been made hunting for such compounds and lithium imide salts have been found to be of great interest despite some limitations. Within the imide family, there is now a rapidly growing interest for lithium bis(fluorosulfonyl) imide, Li[(FSO2)2N] (LiFSI) to be used in liquid electrolyte owing to well balanced properties such as absence of release of HF under normal operation, low viscosity and high conductivity, high-rate and excellent low temperature performances. In addition storage of LiFSI salt based batteries at both high temperature and fully charged states is no more an issue [2]. The thermal stability comparative study of a fully lithiated graphite powder in presence of carbonates based electrolytes with LiPF6 and LiFSI lithium salt is presented. DSC analysis revealed quite different behaviors. In the LiPF6 case, a broad exotherm starts around 120°C, with the SEI breakdown, ending at 250°C whereas for LiFSI salt, a broad but weak peak starting around 80°C is followed by a sharp exotherm around 200°C. With the help of GC/MS, 19F NMR and ESI-HRMS analyses, the reaction mechanisms involved in these different thermal events were studied and solutions are proposed to noticeably decrease the energy released in the LiFSI case. On the other hand, detailed investigations of the combustion behavior of LiPF6 or LiFSI-based carbonate electrolytes and 1.3 Ah pouch cells were conducted with the objective of getting a better knowledge of lithium-ion battery system fire induced thermal and chemical threats. The well-controlled experimental conditions provided by the Tewarson calorimeter [3] have enabled the accurate evaluation of fire hazard rating parameters such as heat release rate and effective heat of combustion and the quantification of toxic effluents (HF, SO2, NOx…). The comparison of results of these two salts will be discussed. [1] D. Lisbona, T. Snee, Process Safety and Environmental Protection 89 (6)(2011) 434. [2] L. Li, S. Zhou, H. Han, H. Li, J. Nie, M. Armand, Z. Zhou, X. Haung, Journal of the Electrochemical Society 158 (2) (2011) A74. [3] P. Ribière, S. Grugeon, M. Morcrette, S. Boyanov, S. Laruelle, G. Marlair, Energy Environ. Sci. 5 (2012) 5271.

Relation between seminal quality and oxidative balance in sperm cells

ObjectivesInfertility is a clinical disorder affecting approximately 15% of reproductive-aged couples worldwide. Recently, the influence of oxidative stress (OS) in decreased semen quality has been discussed. OS corresponds to an imbalance between oxidants and antioxidants defenses, present in the organism. High levels of reactive oxygen species (ROS) damage biomolecules present in sperm cells and may lead to the loss of membrane integrity, DNA fragmentation or even to death by apoptosis. This study aimed to evaluate the correlation between human semen clinic parameters and parameters that assessed the presence of OS. Material and methodsA total of 32 semen samples, obtained from a randomized group of donors, were included in this study. Basic semen parameters were analyzed according to the WHO's guidelines. The total antioxidant capacity of sperm cells was measured as well as the expression of certain antioxidant proteins, namely superoxide dismutase (SOD) and glutathione peroxidase 4 (GPx4), by colorimetric techniques and immunoblotting, respectively. The effect of ROS in spermatozoa protein oxidation was analyzed by determining the presence of 3-nitrotyrosine and carbonyl groups, by slot blot. Lipid peroxidation was evaluated, by performing the thiobarbituric acid reactive substances (TBARS) assay with colorimetric tests. ResultsThe results indicated that SOD was negatively correlated with viscosity (p=0.035), volume (p=0.004) and carbonyl groups presence (p=0.005). This protein also showed a positive correlation with the presence of tail defects in sperm cells (p=0.044). In turn, GPx4 showed a negative correlation with the presence of non-progressive motile spermatozoa (p=0.012). TBARS assay revealed a negative correlation with the concentration of sperm cells (p=0.000) and the total number of spermatozoa (p=0.026), but, in turn, this assay showed a positive correlation with the volume of semen (p=0.038). ConclusionIt was concluded that the seminal quality is affected by the oxidative balance in sperm cells. The obtained results suggest that lipid peroxidation leads to a reduction in sperm concentration; antioxidant proteins protect the spermatozoa against protein oxidation and contribute to an increased sperm motility and normal semen viscosity. Thus, evaluation of oxidative parameters may be a useful tool for male infertility diagnosis and follow-up of antioxidant treatments.

Constant Stress and Pressure Rheology of Colloidal Suspensions.

We study the constant stress and pressure rheology of dense hard-sphere colloidal suspensions using Brownian dynamics simulation. Expressing the flow behavior in terms of the friction coefficient-the ratio of shear to normal stress-reveals a shear arrest point from the collapse of the rheological data in the non-Brownian limit. The flow curves agree quantitatively (when scaled) with the experiments of Boyer et al. [Phys. Rev. Lett. 107, 188301 (2011)]. Near suspension arrest, both the shear and the incremental normal viscosities display a universal power law divergence. This work shows the important role of jamming on the arrest of colloidal suspensions and illustrates the care needed when conducting and analyzing experiments and simulations near the flow-arrest transition.

Molecular Processes Leading to Shear Banding in Well Entangled Polymeric Melts.

We have performed hi-fidelity dissipative particle dynamics (DPD) simulations of shear flow of polymeric melts in a broad range of system sizes and two entanglement densities to determine the critical conditions for occurrence of both transient and steady shear banding. Here, we report, for the first time, simulation results that clearly demonstrate the consecutive steps leading to shear banding, that is, the stress overshoot drives locally inhomogeneous chain deformation and thus spatially inhomogeneous chain disentanglement; in turn, the localized jump in the entanglement density along the velocity gradient direction results in a considerable jump in normal stress and viscosity, which ultimately leads to shear banding. Overall, our observations are consistent with prior experimental studies, and an explanation for the stability of steady and transient shear banded flows is postulated based on the well-known interfacial stability mechanism of stratified polymeric fluids.

Microphase transitions of block copolymer/homopolymer under shear flow

Cell dynamics simulation is used to investigate the phase behavior of block copolymer/homopolymer mixture subjected to a steady shear flow. Phase transitions occur from transverse to parallel and then to perpendicular lamellar structure with an increase of shear rate and this is the result of interaction between the shear flow and the concentration fluctuation. Rheological properties, such as normal stress differences and shear viscosity, are all closely related with the direction of the lamellae. Furthermore, we specifically explore the phase behavior and the order parameter under weak and strong shear of two different initial states, and realize the importance of the thermal history. It is necessary to apply the shear field at the appropriate time if we want to get what we want. These results provide an easy method to create ordered, defect-free materials in experiment and engineering technology through imposing shear flow.

Total antioxidant capacity and lipid peroxidation in semen of patient with hyperviscosity.

Semen hyperviscosity (SHV) is one of the factors involved in deficiency in sperm function. This research aimed to evaluate seminal plasma total antioxidant capacity (TAC) and malondialdehyde (MDA) levels in infertile patients with hyperviscous and non-hyperviscous semen samples to understand whether hyperviscous semen is associated with oxidative damage in infertile subjects. In this cross sectional study, 59 semen samples were provided by fertile (n=12) individuals as control, infertile patients with normal viscosity (n=25) and infertile patients with hyperviscosity (n=22). After semen parameters examination, semen viscosity was studied by glass pipettes. Seminal plasma TAC and MDA levels were measured by ferric reducing of antioxidant power (FRAP) and thiobarbituric acid reaction (TBAR) methods, respectively. A probability less than 0.05 was considered statistically significant throughout the article. The mean of sperm parameters including: counts, motility and normal morphology in patients with hyperviscosity were significantly lower than those in non-hyperviscosity patients (p<0.05, p<0.01 and p<0.001, respectively). The mean of seminal plasma TAC value in seminal plasma of non-hyperviscosity patients (1710.31 ± 458.67 µmol/l) was significantly (p<0.01) higher than that of hyperviscosity group (1230.25 ± 352 µmol/l). A trend toward a higher mean of seminal plasma MDA value was estimated for hyperviscous group compared with non-hyperviscous (1.01 ± 0.41 nmol/ml vs. 0.94 ± 0.28 nmol/l); however, it was nonsignificant. Hyperviscous semen impairs seminal plasma TAC which is eventually associated with sperm membrane lipid peroxidation.

Numerical evaluation of blood viscosity affecting pulse wave propagation in a fluid-structure interaction model.

High blood viscosity often causes cardiovascular diseases, such as hypertension, atherosclerosis and thrombosis. It is proven that blood viscosity plays an important role in cardiovascular functions. In this paper, pulse wave characteristics with normal and high blood viscosities are presented in detail to evaluate how blood viscosity affects pulse wave propagation. A fluid-structure interaction is employed to solve for pulse wave characteristics. The results show that increased blood viscosity does not change the time delay of wave propagation. However, high viscosity reduces the velocity amplitude, while it enhances the pressure level. This study provides physical insight for evaluating blood viscosity leading potentially to pulse wave changes.

Study on the Remaining Oil Distribution with Domain Decomposition Simulation Method

Block 127 reservoir was a typical heavy oil reservoir with normal pressure system, high density and viscosity. The block was low production because formation water invaded seriously. Well condition and effects of measure were badly year after year. In order to clarify remaining oil distribution rule, east and west typical well group of block in 127 was chosen. Careful research in typical well group and multiple well group synthesis research method was used to research with numerical simulation method. The sub-zone sand body residual oil saturation chorizo-gram of well groups and entire block were mapped, qualitative and quantity analysis residual oil distribution rule was studied on plane and vertical. The larger and more complex structure reservoir, used to Domain decomposition method with the typical well group fine research, multi-well-group integrated research method is feasible. The knowledge of residual oil is made deeply and these works offer technique support for block heavy oil reservoir.

Mechanistic studies on the flavin-dependent N6-lysine monooxygenase MbsG reveal an unusual control for catalysis

The mechanism of Mycobacterium smegmatis G (MbsG), a flavin-dependent l-lysine monooxygenase, was investigated under steady-state and rapid reaction conditions using primary and solvent kinetic isotope effects, substrate analogs, pH and solvent viscosity effects as mechanistic probes. The results suggest that l-lysine binds before NAD(P)H, which leads to a decrease in the rate constant for flavin reduction. l-lysine binding has no effect on the rate of flavin oxidation, which occurs in a one-step process without the observation of a C4a-hydroperoxyflavin intermediate. Similar effects were determined with several substrate analogs. Flavin oxidation is pH independent while the kcat/Km and kred/KD pH profiles for NAD(P)H exhibit single pKa values of ∼6.0, with increasing activity as the pH decreases. At lower pH, the enzyme becomes more uncoupled, producing more hydrogen peroxide and superoxide. Hydride transfer is partially rate-limiting at neutral pH and becomes more rate-limiting at low pH. An inverse solvent viscosity effect on kcat/Km for NAD(P)H was observed at neutral pH whereas a normal solvent viscosity effect was observed at lower pH. Together, the results indicate a unique mechanism where a rate-limiting and pH-sensitive conformational change occurs in the reductive half-reaction, which affects the efficiency of lysine hydroxylation.

Seminal hyperviscosity is not associated with semenogelin degradation or sperm deoxyribonucleic acid damage: a prospective study of infertile couples

To investigate the association between seminal hyperviscosity, the extent of semenogelin degradation, and sperm DNA integrity (DNA fragmentation index [DFI] and high DNA stainability [HDS]) in semen from infertile couples. Prospective study. University-affiliated fertility center. Twenty-four consecutive infertile couples with moderate or high seminal viscosity (hyperviscosity group) and 25 consecutive infertile couples with normal semen viscosity (control group) undergoing standard IVF. Semen volume and seminal hyperviscosity, sperm concentration, motility, and morphology, level of semenogelin degradation (by immunoblotting), and sperm chromatin damage (by sperm chromatin structure assay and expressed as %DFI and %HDS) were evaluated. Sperm %DFI and %HDS in the hyperviscosity group and the control group and the relationship between the extent of semenogelin degradation and seminal viscosity. Semen volume in couples with moderate and high seminal viscosity was significantly lower as compared with the control group. In addition, total motility and normal morphology were significantly lower in the couples with high seminal viscosity as compared with the control group; however, there were no significant differences in sperm %DFI and %HDS between the hyperviscosity group and the control group. In addition, there was no relationship between the extent of semenogelin degradation and seminal viscosity. Our data suggest that seminal hyperviscosity (a posttesticular factor) is not an important cause of sperm DNA damage. Moreover, seminal hyperviscosity is not related to the degree of semenogelin degradation.