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Open access

M. Jaskowski, K. Pieła and L. Błaz

Abstract

The influence of the number of extrusion steps in KoBo method (at the same total extrusion ratio of λ = 100) on structure, mechanical properties and work hardening characteristics of AlMg4.5 and AlMg4.5Mn (AA5083) alloys was investigated. It was found that one-step extrusion leads to the formation of recrystallised structure of the material, while the use of two-step extrusion yields a fibrous structure of a “mixed” type, i.e. containing areas where the intensive recovery effects are associated with partially recrystallised structure. As a consequence, the strength properties of the latter extrudate are much higher in both as extruded state and after the subsequent cold rolling. In all cases, the tensile stress-strain curves of the extrudates show the flow stress serrations that are typical for the Portevin - LeChatelier (P-L) effect. In a few tensile tests, the P-L effect was preceded by the plastic flow instability being typical for the occurrence of Lüders bands. Both AlMg4.5 and AlMg4.5Mn extruded wires show a monotonic increase of the work hardening that results from the following cold deformation in the groove rolling.

Open access

K. Pieła, L. Błaz and M. Jaskowski

Abstract

Commercial purity aluminum was extruded by means of KoBo method at varied processing parameters. Received extrudates, with different mechanical and electrical properties and work hardening behavior, were obtained. It was found, that some conditions of KoBo extrusion process such as low initial billet temperature, low extrusion rate and low frequency of oscillating die lead to extremely high strength and high electrical resistivity of the material. The absence of work hardening (up to 40% strain) during subsequent groove rolling is also a specific feature of received materials. It was suggested that mentioned features are related to the development of overbalance concentration of point defects (clusters) generated during the extrusion process. During following cold rolling of the extrudate, mentioned defects annihilate at gliding dislocations and make the dislocation climbing and their rearrangement easier. Therefore, until the exhaustion of this mechanism, the hardening of material during cold rolling is very limited. Following increase of the material strengthening at higher rolling strains point to the return of the material to its typical behavior observed for cold deformed aluminum produced by conventional hot extrusion.

Open access

Jan Olechnowicz and Jędrzej M. Jaśkowski

Abstract

The objective of this study was to present a relationship between mastitis in the post-calving period and fertility traits of dairy cows. The threshold of 200,000 cells/ml for somatic cell count is used as a reference for healthy quarters of the cow’s udder. The genetic correlation between mastitis and somatic cell count is strong (from 0.7 to 0.8). Although heritability for fertility traits is low (from 0.01 to 0.02), the genetic standard deviation for mastitis varies from 1.2 to 7.0 percentage units, suggesting that genetic gain can be achieved by selecting for mastitis. Results of this study suggest that mastitis in the postpartum period can have a markedly negative impact on the reproductive performance of dairy cows. The synergistic effect of common conditions (somatic cell count, body condition score and lameness score) or other factors (e.g. heat stress, fertility management, the presence of repeat breeders) also lowers fertility of cows. Production of milk with fewer than 100,000 cells/ml leads to improved health and fertility in the cows.

Open access

D. Bukowska, B. Kempisty, M. Jackowska, M. Woźna, P. Antosik, H. Piotrowska and J. Jaśkowski

Differential expression of epidermal growth factor and transforming growth factor beta isoforms in dog endometrium during different periods of the estrus cycle

Both epidermal growth factor (EGF) and transforming growth factor (TGF) play an important physiological role in the processes of proliferation and differentiation of several different cell types. However, the expression profiles of these factors in domestic bitches endometrium are still poorly recognized. The aim of the present study was to identify and analyze the differential expression of these factors in various stages of the estrus cycle.

Endometrial tissue from proestrus (n=17), estrus (n=10), day 10 diestrus (n=15), day 35 diestrus (n=18) and anestrus (n=25) was collected soon after ovariohysterectomy. Total RNA was isolated from the endometrium by means of Chomczyński and Sacchi method, treated by DNase I, and reverse-transcribed into cDNA. Quantitative analysis of EGF, TGFβ1, TGFβ2, and TGFβ3 cDNA was performed by real-time quantitative polymerase chain reaction (RT-PCR).

EGF expression in canine endometrium was increased in the estrus stage as compared to proestrus (p<0.05), day 10 diestrus (p<0.05), day 35 diestrus (p<0.01) and anestrus (p<0.001). We also found the differences in EGF expression between day 10 and day 35 of estrus as well as between day 35 of estrus with anestrus (p<0.05, p<0.01, respectively). The TGFf1 transcript contents were also higher in estrus as compared to other stages (p<0.01). The TGFβ2 and TGFβ3 in the estrus stage was increased compared to proestrus, day 10 diestrus, day 35 diestrus and anestrus (p<0.05).

We proved that expression of EGF and TGFβ transcript isoforms is related to the phase of estrus in bitches and therefore may be regulated by specific hormone concentrations during these periods. Our results confirm the hypothesis that these growth factors play a role in the regulation of biochemical changes in the endometrial tissues during the estrus cycle.

Open access

D. Bukowska, B. Kempisty, M. Jackowska, M. Woźna, P. Antosik, H. Piotrowska and J. Jaśkowski

Analysis of integrins and vascular endothelial growth factor isoforms mRNA expression in the canine uterus during perimplantation period

Integrins are the major receptors within the extracellular matrix (ECM) that mediate several functions connected with cell life and metabolism, such as cell adhesion, migration, cytoskeletal organization, proliferation, survival, and differentiation. A vascular endothelial growth factor (VEGF) is one of the most important angiogenic factors. It has been suggested that the expression of this gene may play crucial physiological roles in reproductive organs.

All investigated endometrial tissues were isolated on day 10-12 after mating. Control bitches, used in this study, were in metestrus, which was determined according to the vaginal cytology and progesterone level in blood. Early pregnancy was verified by flushing the uterine horns with PBS. Total RNA was isolated from the bitches endometrium by means of the Chomczyński and Sacchi method, treated by DNase I, and reverse-transcribed into cDNA. A quantitative analysis of integrins α2b, β2 and β3, VEGF 164, 182 and 188 cDNA was performed by RT-PCR.

In results we have shown an increased expression of all investigated genes (integrins α2b, β2 and β3, VEGF 164, 182, and 188) in pregnant bitches uterus as compared to non-pregnant females (p<0.001).

Our results indicated that the expression of genes encoding integrins and vascular endothelial growth factors is different in relation to the time of the embryo implantation and it is increased in the first period of this process. This may be associated with the induction of specific mechanisms responsible for receptivity of uterus following the embryo attachment. In addition, all of investigated genes are up-regulated in a pregnancy-specific manner and the increased expression of these genes may regulate the uterus function during the implantation of canine embryos.

Open access

Agata Józefiak, Mariusz Woźniak and Jędrzej M. Jaśkowski

Abstract

MERS (Middle East Respiratory Syndrome) is a viral disease of the respiratory system caused by coronaviruses (CoV), which can be contagious to both animals and humans. It was first described in 2012 in Saudi Arabia and very quickly its occurrence was found in European countries. Initially, it was associated with mild changes within the respiratory system, until a new type of virus was isolated in a patient with severe pneumonia and renal failure, who died. The study showed a close relationship between the virus isolated from the patient’s cells with HKU4 and HKU5 coronaviruses, previously isolated from bats. The presence of the same virus was found in a patient from Qatar with a similar clinical image. MERS infections, despite relatively low infectivity, are characterized by high mortality (30%). It is believed that the most likely source of the virus for humans are camels. The objective of this article is to review and discuss data on the risk factors of MERS-CoV zoonotic transmission from animals to humans.

Open access

D. Bukowska, B. Kempisty, H. Piotrowska, P. Zawierucha, K. Brussow, J. Jaśkowski and M. Nowicki

The in vitro culture supplements and selected aspects of canine oocytes maturation

The maturation of oocytes is one of the most important steps determining their developmental competence. Due to the low percentage of oocytes of bitches that reach the MII stage, searching for reagents that may stimulate the growth and maturation of oocytes is still present in this species of mammals. The most important media supplements include gonadotropins (LH, FSH, hCG), growth factors (IGF, TGF, EGF, FGF), progesterone and follicular fluid. It is suggested that the supplement of EGF, and/or follicular cells may have an important influence on the percentage of cells that reach the MII stage. Despite plenty of research based on the improvement of bitch oocytes in vitro culture, the results obtained are still unsatisfactory. Moreover, in the long stages of canine oocytes maturation many molecular and morphological modifications (including changes in mitochondria structure and configuration in the cytoplasm) are involved.

In this article, the influence of selected media supplements on the efficiency of bitch oocytes in vitro maturation was described. The molecular and morphological modifications during canine oocytes maturation were also considered in the text.

Open access

J.M. Jaśkowski, M.P. Polak, A. Marszałek, K. Nowak, H. Frąckowiak and J. Olechnowicz

Abstract

Bovine neonatal pancytopenia (BNP), a newly emerged syndrome of discussed etiology in calves, has been diagnosed since 2006. Here we describe first cases of BNP in Poland. Between September 2008 and April 2011, 62 cases of BNP were diagnosed in dairy calves. Bleeding skin lesions were mostly pronounced in summer and early autumn. Severe thrombocytopenia was observed in all sick animals. All calves came from herds vaccinated against BVDV infection with PregSure BVD vaccine (Pfizer). Substitution of colostrum from dams of BNP positive calves with colostrum from dams from herds free of BNP was the only effective measure to avoid new cases in affected herds.

Open access

Marta Rybska, Sandra Knap, Katarzyna Stefańska, Maurycy Jankowski, Agata Chamier-Gliszczyńska, Małgorzata Popis, Michal Jeseta, Dorota Bukowska, Paweł Antosik, Bartosz Kempisty and Jędrzej M. Jaśkowski

Abstract

The superfamily of transforming growth factors β (TGF-β) consists of cytokines that are crucial in regulating the organism’s biological functions and includes three isoforms of TGF-β protein, Anti-Müllerian Hormone (AMH), inhibin A and B, activins, 20 bone morphogenetic proteins (BMP1-20) and 9 growth factors (GDF1-9). Their signal transduction pathway involves three types of membrane receptors that exhibit a serine/threonine kinase activity, as well as the Smad proteins. After ligand binding, the Smad proteins are phosphorylated and translocated to the nucleus, where they interact with transcription factors and affect gene expression. TGF-β family members are involved in cell growth and differentiation, as well as chemo-taxis and apoptosis, and play an important role during an inflammation. Defects in TGF-β proteins or in their signalling pathway underlie many severe diseases, such as systemic lupus, systemic scleroderma, bronchial asthma, atherosclerosis, hyperthyroidism or cancer. These factors are also crucial in mammal reproductive functions, as they are involved in folliculogenesis, steroidogenesis, ovulation, maternal-embryo interaction, embryo development and uterine decidualization. Their defects result in issues with fertility. This review focuses on the relevance of TGF-β family members in a mammal reproduction with an emphasis on three TGF-β isoforms, inhibins A and B, GDF-9 and their signal transduction pathway.

Open access

Marta Rybska, Sandra Knap, Maurycy Jankowski, Blanka Borowiec, Michal Jeseta, Dorota Bukowska, Paweł Antosik, Michał Nowicki, Maciej Zabel, Bartosz Kempisty and Jędrzej M. Jaśkowski

Abstract

Ovarian cysts remain to be one of the most common and serious problems in reproduction of farm animals, as well as humans. Apart from causing the fall in reproductive potential of the ovaries, occupying the place in which folliculogenesis and oogenesis occur, they also cause hormone imbalances, by preventing corpus luteum formation, hence lowering the amount of steroid hormone production. While singular cysts rarely affect fertility, hormone fluctuations that are associated with their presence promotes their multiplication, which usually has more adverse effects. While the cysts are easily detectable in humans, possessing distinct echography while examined by ultrasound, multiple factors prevent widespread use of effective detection methods among large herds of farm animals. Because of lack of noticeable symptoms of early stages of such malignancies, they rarely get detected before the animal stops to exhibit symptoms of heat. That causes scientific research to be focused on not only methods of detection, but also the ways to negate the effects of ovarian cysts and bring the affected specimen back to reproductive potential. Despite that, high costs of diagnosis and treatment, cause them to be uncommon on commercial farms. As lack of fertility eliminates animals from breeding purposed herds, ovarian cysts persist as a cause of large losses of the animal husbandry business. Continuous research, focused on natural examples of ovarian cysts should be conducted, in order to improve methods of detection, prevention, treatment and recovery from the effects of ovarian cysts.