Umut Taşdemir

Effects of various cryoprotectants on bull sperm quality, DNA integrity and oxidative stress parameters ☆

The objectives of this study was to compare the effects of type and concentration of cryoprotectants glycerol (G), ethylene glycol (EG) and dimethyl sulfoxide (DMSO) on the plasma membrane and DNA integrity as well as antioxidant activity of cryopreserved Eastern Anatolian red bull sperm. Ejaculates were collected from the three bulls using an artificial vagina twice a week. The ejaculates were pooled to increase the semen volume for replication and to eliminate variability among the evaluated samples. The pooled ejaculates were also split into seven equal experimental groups and diluted with the modified base extender to a final spermatozoa concentration of 15×10(6)/ml. The extended samples were cooled slowly to 4°C and equilibrated for 4h. They were then loaded into 0.25ml French straws and frozen using a digital freezing machine at 3 programmed rates: -3°C/min from +4°C to -10°C, -40°C/min from -10°C to -100°C, and -20°C/min from -100°C to -140°C. Thereafter, the straws were plunged into liquid nitrogen at -196°C. Frozen straws were thawed individually at 37°C for 30s in a water bath to analyse progressive motility and sperm motion characteristics as well as membrane integrity using hypo-osmotic swelling test. Biochemical assays were performed in a spectrophotometer using commercial kits. DNA damage was evaluated by Comet Assay using Image Analysis System. 6% G exhibited the greatest percentages of CASA (43.7±2.92%) and progressive (26.4±2.64%) motilities when compared to the other groups (P<0.001). 6% G and 6% EG showed the greatest values of preserved membrane integrity (P<0.001). 6% DMSO and 3% EG + 3% DMSO resulted in greater chromatin damage than the other groups (P<0.001). The antioxidant activities of GPx, GSH, and CAT as well as the total antioxidant activity were affected by the type of cryoprotectant; notably, 2% G+2% EG+2% DMSO yielded the lowest activities when compared to the other groups (P<0.001). In conclusion, no advantages were found in using EG or DMSO to replace G in bull sperm cryopreservation. Freezing with cryoprotectant 6% G yielded the best post-thaw sperm characteristics for Eastern Anatolian Red bull spermatozoa.

Formulation of zolmitriptan sublingual tablets prepared by direct compression with different polymers: In vitro and in vivo evaluation

First-pass metabolism can be overcome by sublingual drug delivery, and quick drug entry into the systemic circulation can be obtained. In certain diseases such as migraine therapy, taking fast pharmacological response is an important criteria. In this study, zolmitriptan sublingual tablets were prepared by direct compression method using different mucoadhesive polymers such as hydroxypropyl methyl cellulose, chitosan and sodium carboxy methyl cellulose at a concentration range of 0.5-5% to reduce flushing action of saliva and provide enough time for drug to be absorbed. Tablets were evaluated for the physical properties, and optimum formulations were chosen for in vivo studies to carry on sheep model. The tablets disintegrated rapidly, and dissolution tests revealed that zolmitriptan was dissolved from the formulation within the compendial limits. This especially showed us that the concentration range of polymers is in acceptable limit. It was also concluded that microcrystalline cellulose, spray-dried lactose and sodium starch glycolate are the appropriate excipient and formulated in good proportions. In vivo studies indicated that formulation containing 5% chitosan has the maximum C(max) and AUC and minimum t(max) values (p<0.05). As a result, sublingual tablet administration of zolmitriptan formulated with appropriate excipients and especially with chitosan seems promising alternative to traditional routes.

Cryopreservation of bull sperm: Effects of extender supplemented with different cryoprotectants and antioxidants on sperm motility, antioxidant capacity and fertility results

The objectives of this study were to compare glycerol (G) and ethylene glycol (EG) at different concentrations and trehalose (T) or cysteine (C; with/without) in Tris extender for cryopreservation of bull semen. Twenty-four ejaculates obtained from three bulls were included in the study. Each ejaculate was divided into four equal aliquots and diluted using both of the Tris extenders with G (5% or 7%) or EG (3% or 5%). After that, each extenders were divided into three equal aliquots and diluted using both of the 5 mM C or 25 mM T, and control (without additives) was cooled to 4 ° C and frozen in 0.25 ml French straws. The addition of 3% and 5% EG without antioxidants resulted in the least Computer-Assisted Sperm motility Analysis (CASA) motility as compared with the other groups. Treatment with 25 mM T in 3% EG beneficially effected acrosome morphology as compared with the other groups. Also, treatment with 3% EG with 25 mM T and 5% EG resulted in a greater rate of total abnormalities. Treatment with 3% G yielded a slightly greater percentage of membrane integrity by Hypo-Osmotic Swelling Test (HOST) assessment than that of the other groups. Treatment with 3% EG with 5 mM C resulted in the greatest concentration of malondialdehyde (MDA). The glutathione peroxidase (GPx) antioxidant activity was increased in the C-treatment groups when compared to the other groups. Treatment with 5% EG and 5 mM C resulted in less chromatin damage and detrimental impacts on tail moment. Treatment with 5% EG led to greater non-return rates of inseminated cows. However, this result was not considered to be statistically important.

Comparing ethylene glycol with glycerol and with or without dithiothreitol and sucrose for cryopreservation of bull semen in egg-yolk containing extenders☆

There are few studies performed for investigating the roles of different ratio and cryoprotectants with dithiothreitol or sucrose on sperm motility characteristics and antioxidant capacities of post-thawed bull spermatozoa. The objectives of this study were to compare glycerol (G) and ethylene glycol (EG) at different concentrations as cryoprotectants and dithiothreitol (D) or sucrose (S) (with/without) as antioxidants in Tris extender for cryopreservation of bull semen. Twenty-four ejaculates obtained from three bulls were included in the study. Each ejaculate was split into four equal aliquots and diluted using both of the Tris extenders with glycerol (5% or 7%) or ethylene glycol (3% or 5%). After that, each extenders were split into three equal aliquots and diluted using both of the dithiothreitol 5mM or sucrose 25 mM, and control (without additives) was cooled to 4 °C and frozen in 0.25-ml French straws. when compared to control, different doses cryoprotectants and antioxidants addition no significantly increased the percentages of post-thaw sperm progressive and motitilities, acrosome abnormality and plasma membrane integrity (P>0.05). However, EG3+S yielded the greatest percentages of the total abnormality (P<0.05). As regard to antioxidant activities G7 and EG5 led to lowest MDA activity with or without D or S but, these results were not supported to the GPx activity (P<0.01). The sperm motion characteristics such as VAP, VCL, ALH and BCF gave significantly different results (P<0.05). When compared the DNA integrity, different doses cryoprotectants without antioxidants addition significantly increased the percentages of the tail intensity and tail moment (P<0.05). There were no significant differences observed in non-return rates among all treatment groups (P>0.05).

Effect of cholesterol loaded cyclodextrin on semen cryopreservation of Aksaray Malakli shepherd dogs of different ages

The objective of the study was to determine the effect of cholesterol-loaded cyclodextrin (CLC) on the quality parameters of semen from Aksaray Malakli Shepherd dogs of different age groups. Forty-eight male dogs were divided into 3 groupings according to their ages (young age (Y): ≤3 years, n: 20; middle age (M): 4-6 years, n: 20; old age (O): ≥7 years; n: 8). The sperm-rich portion of the ejaculate from each dog was divided into four aliquots and extended with either tris as a control (C) or tris loaded with 0.5, 1.0, and 1.5 mg/120 × 106 CLC as low (L), intermediate (I), and high (H) doses, respectively. Following equilibration for at least half an hour, the straws were frozen in nitrogen vapor and then stored in liquid nitrogen at least for 48 h. Later, the frozen straws were thawed in a water bath for spermatological evaluation. Significant differences were observed between different age groups in terms of the spermatological parameters (p < 0.05). The evidence suggests that increasing age is associated with poor in-vitro spermatological parameters and CLC was able to protect the acrosome integrity from cryo-damage during the freeze-thawing process. Better semen freezability characteristics were obtained at young ages, considering the overall parameters.