Publications by authors named "Ioannis Nanas"

Article Synopsis
  • Global warming poses a serious threat to dairy farming by impacting cow welfare, fertility, and economic viability, especially due to increased summer temperatures even in temperate areas.
  • Dairy cows adapt to heat stress through various biological and behavioral changes, such as releasing heat shock proteins and altering hormone levels, though these adaptations are not enough to fully maintain fertility during hot seasons.
  • Despite strategies to mitigate heat stress and improve milk production, fertility rates remain low in summer because maintaining reproductive health relies on a complex interplay of energy balance and hormonal regulation.
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Flaxseed and lupin seed were offered as an alternative dietary approach in dairy cows, through the partial substitution of soybean meal. Milk production and fertility traits were investigated. A total of 330 animals were allocated into two groups, treated ( = 176) and control ( = 154).

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Article Synopsis
  • The study examined how replacing half of the soybean meal in dairy cow diets with flaxseed and lupins affects milk and cheese production.
  • Both groups of cows had similar milk yields, but the FL group produced milk with more beneficial fatty acids and lower protein carbonyls compared to the control group.
  • The resulting white cheese from the FL diet had a healthier fatty acid profile and maintained similar taste and texture characteristics to the cheese from the control group.
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  • Heat stress negatively impacts milk production and reproduction in dairy cows, leading to economic losses; certain cows have developed thermotolerance mechanisms that could be bred for improved resilience.
  • Advances in genomics allow researchers to identify genetic variations (SNPs) linked to thermotolerance, which can enhance selective breeding programs intended to produce more heat-resistant cows.
  • The study identified specific genetic markers associated with thermotolerance, particularly in genes linked to Heat Shock Proteins, suggesting paths for improving dairy cattle adaptation to heat stress.
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In this study, the transcriptome of oviductal epithelial cells and certain characteristics of their extracellular vesicles of dairy cows were described under thermoneutral and heat stress conditions. Twenty cows were compared in springtime at THI = 65.6 ± 0.

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The aims of the present study were to examine the effects of HSP70 addition in the in vitro culture medium of day 3 embryos on their developmental competence and quality. Bovine oocytes ( = 1442) were in vitro matured, inseminated and cultured for the first two days according to standardized methods. The presumptive zygotes were randomly allocated in three experimental groups: Control, C (embryos cultured at 39 °C throughout the culture period), group C41 (temperature was raised to 41 °C from the 48th to 72nd h post insemination (p.

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It is known that heat stress decreases dry matter intake in cattle with impacts on milk production and fertility. Ghrelin is an orexigenic hormone with suppressive effects on reproduction. In this study, we investigated the effects of heat stress and gestational status on ghrelin secretion and its possible associations with DMI in Holstein cattle.

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Article Synopsis
  • This study examined the impact of heat stress on pregnant dairy cows by comparing ultrasound findings in winter (group W) and summer (group S).
  • Results showed that summer cows experienced higher cortisol levels and lower progesterone, along with reduced echogenicity of the corpus luteum and placentomes.
  • Additionally, the umbilical artery's diameter and blood volume were smaller in summer cows, indicating that heat stress may negatively affect fetal blood supply and the structure of reproductive tissues.
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The negative effects of heat stress on dairy cattle's fertility have been extensively studied, but the relevant knowledge for beef cattle is rather limited. The aims of this study were to investigate the effects of HS during in vitro maturation on the developmental potential of oocytes derived from Limousine and Holstein cows and to estimate the effect of the differential gene expression of important genes in oocytes, cumulus cells and blastocysts in the growth competence between the breeds. In seven replicates, cumulus oocyte complexes from Holstein and Limousine cows were matured for 24 hr at 39°C (controls C; Hol_39, Lim_39) or at 41°C from hour 2 to hour 8 of IVM (treated T; Hol_41, Lim_41), fertilized, and presumptive zygotes were cultured for 9 days at 39°C.

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Heat shock protein 70 (HSP70) is a chaperon that stabilizes unfolded or partially folded proteins, preventing inappropriate inter- and intramolecular interactions. Here, we examined the developmental competence of in vitro matured oocytes exposed to heat stress with or without HSP70. Bovine oocytes were matured for 24 h at 39 °C without (group C39) or with HSP70 (group H39) and at 41 °C for the first 6 h, followed by 16 h at 39 °C with (group H41) or without HSP70 (group C41).

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Objectives of this study were to characterize the effects of heat stress on pregnancy associated glycoproteins (PAG) and progesterone and its involvement in embryo survival. In trial 1, blood samples collected from days 29 to 36 post insemination were examined for the comparison of PAG concentrations between winter (n = 3721) and summer (n = 2388). In trial 2, embryo losses were assessed in winter (n = 144) and in summer (n = 133), in days 31 or 32 of pregnancy.

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It is well documented that heat stress (HS) causes subfertility in dairy cows. However, during the last ten years we have been observing that, under high temperature-humidity index (THI ≥ 75), despite the overall reduced fertility, some cows conceive at the first artificial insemination (AI). Here, we examined distinctive features of cows with conserved fertility under severe HS.

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Background: Allogeneic cardiosphere-derived cells (CDCs) exert cardioprotective effects when administered intracoronarily after reperfusion in animal models of acute myocardial infarction (AMI). The "no-reflow" phenomenon develops rapidly post-reperfusion and may undermine the efficacy of cell therapy, due to poor cell delivery in areas of microvascular obstruction (MVO). We hypothesized that CDC-induced cardioprotection would be enhanced by cell administration prior to reperfusion, when microvasculature is still relatively intact, to facilitate widespread cell delivery within the ischemic area.

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Heat stress causes subfertility in cattle by inducing alterations in steroidogenic capacity, follicular function and ovulation defects, which eventually negatively affect oocyte quality and embryo survival. Here, the effects of short, moderate temperature elevation during IVM, on embryo yield, and on the expression of various genes was evaluated. In 8 replicates, cumulus oocyte complexes (COCs) were matured for 24 h at 39 °C (controls n = 605) or at 41 °C from hour 2 to hour 8 of IVM (treated, n = 912), fertilized, and presumptive zygotes were cultured for 9 days at 39 °C.

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Objective: Cardiosphere-derived cells (CDCs) have been shown to reduce infarct size after myocardial infarction (MI). In the present study we investigated the safety and efficacy of global intracoronary administration (GIA) of CDCs or CDC-conditioned medium (CM) immediately after reperfusion in a rat model of ischemia-reperfusion.

Methods: CDCs were grown from myocardial biopsies obtained from male Wistar Kyoto rats (WKY).

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The Pressure Unloading Left Ventricular Assist Vevice (PULVAD) is a novel implantable counterpulsation LVAD, designed to provide ventricular unloading with augmentation of LV performance and retention of pulsatility. We assessed the effects of the PULVAD on hemodynamics and LV mechanoenergetics in seven farm pigs with acute ischemic heart failure. The PULVAD was implanted in the thorax and was connected to the ascending aorta.

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Background: The mitochondrial Na/Ca exchanger (mNCX) has been implicated in the pathogenesis of arrhythmogenicity and myocardial reperfusion injury, rendering its inhibition a potential therapeutic strategy. We examined the effects of CGP-37157, a selective mNCX inhibitor, on arrhythmogenesis, infarct size (IS), and no reflow area (NRA) in a porcine model of ischemia-reperfusion.

Methods: Forty pigs underwent myocardial ischemia for 60 minutes, followed by 2 hours of reperfusion.

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The effect of ramipril (an angiotensin [AT]-converting enzyme inhibitor), telmisartan (an AT-II type 1 receptor blocker), or their combination on inflammation and lipid peroxidation was assessed in 37 patients with type 2 diabetes who were free of coronary artery disease. All regimens were associated with a significant reduction of C-reactive protein and oxidized low-density lipoprotein cholesterol serum levels (p <0.001).

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