Use of an aromatase inhibitor for ovarian synchronization in cattle

Letrozole is a third-generation aromatase inhibitor approved for use in post-menopausal women to treat hormone-responsive breast cancer. Letrozole is used off-label in women for the induction of ovulation and for use in ovarian stimulation. The overall objective of this thesis was to determine the effect of letrozole on ovarian function using the bovine model. In the first study, letrozole was formulated into a silicone intravaginal device consisting of a small or a large surface area compared to a wax-based device or a control intravaginal device given for 8 days in pubertal heifers. The large-surface area device resulted in the greatest plasma letrozole concentration throughout the treatment period. The biological effect on the ovaries was also most profound in the large surface area group where the dominant follicle was largest at the time of device removal and plasma estradiol concentrations decreased the most during device insertion. In the second study, letrozole residues in milk were characterized in lactating dairy cattle. A silicone letrozole-releasing device (LRD) was inserted for 4 days, blood and milk sampling were performed at 12-hour intervals, and a partial validation for letrozole in milk was done using tandem mass spectrometry. Although letrozole was detected in milk, maximum concentration of letrozole was significantly lower in milk than in plasma. There were no differences in the elimination half-life or time to maximum concentration for letrozole in milk or plasma. The objective of the third study was to determine if letrozole would increase the superovulatory response in cattle. Non-lactating cows were given an LRD or a sham device at the time of transvaginal follicular ablation to induce wave emergence. At wave emergence, cows were given 8 doses of follicle-stimulating hormone at 12-hour intervals and were artificially inseminated 48 hours after prostaglandin (PGF). The LRD group exhibited estrus significantly later and estrus was more synchronous than the sham group. However, the LRD group had a lower proportion of quality one embryos and transferable embryos than the sham group. The objective of the fourth study was to characterize the effect of letrozole on follicular function and oocyte competence in cattle in three experiments. In the first experiment, transvaginal ablation was done to induce wave emergence and an LRD or sham device was given for 4 days followed by follicular aspiration to obtain granulosa cells for gene expression. In the second experiment following a 4-day LRD or sham device, frequent blood collections were done for analysis of plasma luteinizing hormone (LH) concentrations. Oocytes were collected that were either immediately denuded and stained or underwent 24 hours of in vitro maturation followed by staining. In the last experiment, following aspiration, oocytes were subjected to in vitro maturation, fertilization, and culture. There was no difference between treatments for gene expression from granulosa cells. Heifers in the LRD group had a significantly higher LH area under the curve and pulse amplitude than the sham group. The oocytes from the LRD group in vitro matured for 24 hours had the highest proportion of oocytes in the MII stage than the other groups. The LRD group following in vitro fertilization had a greater proportion of blastocysts and transferable embryos than the sham group. The objectives of the fifth study were to determine the interval to ovulation following LRD treatment, compare an LRD-based synchronization to commercially used protocols for fixed-time artificial insemination (FTAI), and to develop a new LRD designed to reduce vaginitis and increase letrozole release. In the first experiment, a 4-day LRD was given at random stages of the estrous cycle followed by PGF at device removal. Cattle (n=10/group; 6 groups) were given GnRH at 48- or 60-hours after PGF, or no GnRH. In the second experiment, the 48-hour interval from PGF to GnRH following a 4-day LRD treatment was chosen for a FTAI trial to compare pregnancy per AI (P/AI). In the third experiment, heifers (n=10/group) were given a newly designed LRD or an LRD designed in study one and frequent blood sampling was performed along with assessment of vaginitis. The 48-hour GnRH cow group ovulated more synchronous than the other groups. Following FTAI, the LRD group had significantly lower P/AI than the other two protocols. The newly designed LRD significantly increased plasma letrozole concentrations and numerically lowered the vaginitis score at device removal. The objectives of the last study were to determine the: interval to estrus following a 4-day LRD or sham device and PGF at device removal, effect of estrous cycle stage when letrozole treatment was initiated on P/AI, and to compare a newly developed LRD protocol to a progesterone-based protocol. Following PGF, no difference was detected in the interval to estrus between the LRD and sham groups. When LRD treatment was initiated during the proestrus period, it did not prevent ovulation. However, treatment during the metestrus period resulted in the highest P/AI. There was no difference in P/AI between a newly developed LRD-based protocol compared to a progesterone-based protocol. In summary, we have determined that intravaginal letrozole treatment can control ovarian function in cattle. Letrozole is not deleterious on the ability of the oocyte to undergo fertilization and can be used for FTAI protocols in cattle. Future studies should address the effect of letrozole during the proestrus period

(Ne)využívání civilní odbornosti příslušníků aktivní zálohy : Nevyužitá příležitost personálních kvalit

Text předkládá výsledky výzkumuzaměřenéhona využívání civilní odbornosti příslušníků Aktivní zálohy ze strany Armády České republiky. Vrámci řešení výzkumu bylo zjištěno, že až na malou skupinu úzce specializovaných jednotek Aktivní zálohy nedochází ani khlubšímu zjišťování civilní odbornosti uvlastních členů ani uchazečů.Text sums up outcomes of researcher focused on utilizing civilian expertise during their service in Czech Army Active Reserve Forces. The main outcome is that Czech Army is not aware of individual civilian expertise of its reservist and except small group of highly specialized units the armed forces are noteven interested in this matter

Strategies for oocyte collection and in vitro embryo production in free-roaming bison herds

Wood bison (Bison bison athabascae) are a threatened subspecies native to North America. Endemic disease in the largest and most genetically diverse wood bison population in Wood Buffalo National Park has resulted in strict monitoring of populations and restricted the transfer of genetics to outside the park. To safeguard the future of wood bison, we are establishing a germplasm biobank through the use of advanced reproductive techniques. Recovery of embryos and semen collected from at-risk populations would reunite bison herds separated by time and space to produce healthy offspring and restore the genetic diversity of wood bison. The recovery of cumulus oocyte complexes (COC) from wild, free-roaming bison herds requires the use of minimal handling COC collection protocols. The following studies (Chapters 2 – 6) investigated novel approaches to improve in vitro embryo production (IVP) through a field-friendly approach. Chapter 2 investigated the effects of in vitro maturation, conventional morphologic COC grading and minimal handling ovarian superstimulation (sustained release follicle stimulating hormone [FSH]) on nuclear and cytoplasmic characteristics of bison COC and IVP through a 3D computer-assisted quantitative assessment. A greater proportion of active mitochondria was located in the central region of the ooplasm and greater mitochondrial clustering was present in low quality oocytes than high quality oocytes. However, additional analysis is required to characterize mitochondria distributions without quantitative software analysis. The bison oocytes had a high incidence of large lipid droplets similar to extended FSH starvation groups in cattle. Unfortunately, the minimal handling ovarian superstimulation treatments implemented in the present study did not increase the number of COC collected or improve embryo production rates. Chapter 3 investigated the effects of ovarian synchronization and a single dose superstimulation protocol using equine chorionic gonadotrophin (eCG) for COC collection and IVP in wood bison. A single dose of 5,000 IU eCG increased the number and size of follicles available for COC collection, more than doubled the number of COC collected for IVP and resulted in the production of more embryos than other groups (approximately 2 embryos per bison). Nonsuperstimulated COC collections done after follicle wave synchronization resulted in greater embryo production than collections done at random stages of the follicular wave. Repeated COC collections after successive wave synchronization resulted in similar follicular counts and embryo production rates within individuals. The greatest number of follicles aspirated, COC collected, and embryos produced occurred in the anovulatory season. Chapter 4 investigated the effects of restraint (lateral recumbency after chemical immobilization vs standing position in a hydraulic chute) and follicular wave status (random vs synchronized) on COC collection efficiency in non-superstimulated bison. It examined the effects of superstimulation treatment (single dose of eCG vs multiple doses of FSH plus human chorionic gonadotrophin [hCG]) and method of administration (field dart vs manual injection) on COC collection efficiency and IVP. The COC collections were done as effectively on sedated recumbent bison as those restrained in a standing position in a hydraulic chute. Ovarian superstimulation using the single-dose eCG protocol was as effective as a multiple-dose FSH protocol and field darting was an effective method of administering superstimulation treatments. The use of ovarian superstimulation resulted in greater IVP efficiencies than random, non-stimulated collections (3.1 vs 1.1 embryos per bison). Chapter 5 investigated the effects of reproductive status (non-pregnant, pregnant, and prepubertal), advancing gestation (pregnant bison, 90- vs 120- days) and follicular wave status (random vs synchronized) on ovarian follicles, COC collection and IVP. Oocytes were collected and embryos were produced from bison at both 90- and 120- days of gestation, but the position of the ovaries at the more advanced stage reduced COC collection efficiency. Yearling pre-pubertal bison provided the most promise as COC donors in the field. They had the highest number of follicles available for aspiration and produced a similar number of embryos (approximately 1 freezable embryo per collection) compared to non-pregnant mature bison. Yearling pre pubertal bison are available for collection throughout the winter season without the limitations imposed by advanced stages of pregnancy or unknown pregnancy status. Chapter 6 investigated the effect of in vitro wood bison embryo characteristics (stage of development, grade, and freeze day) on the post-thaw viability of pre-implantation IVP embryos characterized by microscopic morphology and establishment of pregnancy after embryo transfer. Morphologic grading was positively related to quantitative viability characteristics, with higher quality embryos having less cryo-damage and higher cell counts than low quality embryos. Morulae survived cryopreservation with less damage than blastocysts, and subsequent transfer resulted in a higher pregnancy rate at 30-days and lower pregnancy loss between 30 to 60 days than blastocysts. The vitrification method of cryopreserving embryos resulted in a pregnancy rate similar to the transfer of fresh embryos. The study produced nine pregnancies at 30 days postovulation, of which 6 made it to term and the birth of five calves. In conclusion, COC collection and IVP methods and procedures investigated throughout this thesis have made COC collection from wild, free-roaming herds a feasible task. Bison stakeholders may now implement these techniques to access inaccessible bison genetics in and around Wood Buffalo National Park

Seasonal Movements and Distribution of Steller’s Eiders (Polysticta stelleri) Wintering at Kodiak Island, Alaska

We used satellite telemetry in 2004–06 to describe the annual movements and habitat use of a segment of the Pacific population of Steller’s Eiders (Polysticta stelleri) that winters at Kodiak Island, Alaska. Information about broad-scale patterns of seasonal distribution and links among annual cycle stages is critical for interpreting population trends and developing conservation strategies. We captured birds in Chiniak Bay at Kodiak Island in late February and early March and monitored the movements after departure from Kodiak Island of 24 satellite-tagged birds: 16 after-second-year (ASY) age class females, one second-year age class female, and seven ASY males. All birds used the same intercontinental migration corridor during spring, but routes and chronology of spring migration appeared to vary by year and among individuals. Sixteen of the 24 birds that were tracked migrated to breeding areas along the Arctic coast of Russia from the Chukotka Peninsula to the Taymyr Peninsula; five birds, assumed to be non-breeding, spent the summer in nearshore waters of Russia and Alaska; and the remaining three birds either died during spring migration or had failed transmitters. Thirteen birds were tracked to molt sites that were broadly distributed along the coast of Alaska. Molt sites included St. Lawrence Island, the Kuskokwim Shoals, Kamishak Bay, and three sites along the Alaska Peninsula. Twelve of these 13 birds returned to Kodiak Island to winter, and a single male wintered on the Alaska Peninsula. Steller’s Eiders marked during winter at Kodiak Island were widely distributed during the breeding season, but a large proportion of marked birds returned to molting and wintering areas in two years of the study.De 2004 à 2006, nous avons recouru à la télémétrie satellitaire pour décrire l’utilisation de l’habitat et les mouvements annuels d’un segment de la population d’eiders de Steller (Polysticta stelleri) dans la région du Pacifique, eiders qui hivernent sur l’île Kodiak, en Alaska. Il est essentiel d’obtenir des données sur les tendances à grande échelle de la répartition saisonnière et des liens entre les divers stades du cycle annuel de ces oiseaux afin d’être en mesure d’interpréter leurs tendances démographiques et d’élaborer des stratégies de conservation. Nous avons capturé des oiseaux dans la baie Chiniak de l’île Kodiak vers la fin février et le début mars. Après notre départ de l’île Kodiak, nous avons surveillé les mouvements de 24 oiseaux pistés par satellite : 16 femelles de plus de deux ans, une femelle de deux ans et sept mâles de plus de deux ans. Tous les oiseaux ont emprunté le même couloir de migration intercontinental au printemps, mais les routes et la chronologie de la migration printanière semblaient varier d’une année à l’autre et d’un individu à l’autre. Seize des24 oiseaux pistés ont migré vers des aires de reproduction situées le long de la côte arctique de la Russie, depuis la presqu’île de Tchoukotkae jusqu’à la presqu’île de Taïmyr; cinq oiseaux, probablement non reproducteurs, ont passé l’été dans les eaux côtières de la Russie et de l’Alaska, tandis que les trois autres oiseaux sont morts pendant la migration printanière ou étaient dotés de transmetteurs défectueux. Treize oiseaux ont été repérés à des sites de mue largement répartis le long de la côte de l’Alaska. Parmi ces sites, notons ceux de l’île Saint-Laurent, du haut-fond de Kuskokwim, de la baie de Kamishak et de trois autres sites le long de la péninsule de l’Alaska. Douze de ces 13 oiseaux sont retournés à l’île Kodiak pour passer l’hiver, et un seul mâle a hiverné dans la péninsule de l’Alaska. Les eiders de Steller qui ont été marqués à l’île Kodiak pendant l’hiver étaient largement répartis pendant la saison de reproduction, mais une grande proportion d’oiseaux pistés sont retournés aux aires de mue et d’hivernage au cours des deux années visées par l’étude

An analysis of the effects of summer school programs

Includes bibliographical references

Mathematical model of electric kart

Tato práce se zabývá vytvořením matematického modelu elektrické motokáry při jízdě na závodním okruhu, pro použití při návrhu parametrů. Klíčový bod pro sestavení matematického modelu je identifikování jízdních odporů na současné elektrické motokáře Katedry elektromechaniky a výkonové elektroniky, Fakulty elektrotechnické, Západočeské Univerzity. Za tímto účelem jsou vypočítány momenty setrvačnosti, čelní plocha motokáry, součinitele aerodynamického odporu a valivého odporu. Tyto hodnoty jsou aplikovány při výpočtech jízdních odporů motokáry třídy Superkart divize 1 v sestaveném simulačním modelu. Na základě vytvořeného matematického modelu elektrické motokáry je simulována jízda na závodním okruhu za účelem návrhu parametrů při zachování konkurenceschopnosti se závodními stroji.Katedra aplikované elektroniky a telekomunikacíObhájenoThis Thesis deals with implementing a mathematical model of an Electric Go-kart driven on a racing track. The model should be used in order to design some important parameters. The key objective for the development of this mathematical model is to define all motion resistances of the Electric Go-kart available at the Department of Electromechanics and Power Electronics, Faculty of Electrical Engineering, University of West Bohemia in Pilsen. To develop this mathematical model, values for these parameters, moment of inertia, front part of go-kart, the coefficients of aerodynamic resistance and rolling resistance were computed. These values were further applied in the calculations of the road resistances of the go-kart class Superkart Division 1 in the developed simulation model. Conditions on a real racing circuit are simulated by the developed mathematical model, to design parameters of the Go-kart competitive to other racing machines

An Analysis of the HESI A2 Examination as a Predictor of Persistence in the Radiography Program at Chippewa Valley Technical College

Plan BStudents graduating from allied health programs, such as radiography, are in high demand to fulfill workforce needs. The program’s goal is to graduate as many qualified students as possible. In addition, nationally accredited radiography programs are required to meet specific benchmarks related to items such as program completion rate. The purpose of this study was to analyze the Health Education Systems, Inc. Admission Assessment (HESI A2) examination scores as a predictor of persistence of students in the Chippewa Valley Technical College radiography program. The data was collected ex post facto and contained HESI A2 exam scores from program students in cohorts from 2019 to 2022. Students’ GPA of select required program general education courses and socioeconomic status were analyzed in relation to the HESI A2 exam scores. A regression analysis was used to evaluate the relationship between independent and dependent variables. The results of this study attempted to explain the relationship between HESI A2 exam scores and student persistence in the radiography program, the relationship between the HESI A2 exam and GPA of select required general education courses, and the relationship between the HESI A2 exam and socioeconomic status of the students. The findings from this study emphasize the importance of the HESI A2 exam as a predictor of persistence in the radiography program. In conclusion, the research study provides program faculty and administration necessary information to continue to rely on the HESI A2 exam scores as a prerequisite for program entry