1,721,101 research outputs found
Daily rhythms of serum lipids in dogs: influence of lighting and fasting cycles
No full textCircadian clock organize a wide array of metabolic functions in a coherent daily schedule and ensure synchrony of this schedule with environmental rhythms. Daily rhythmicity of lipid metabolism has been described in rodents and ruminants. We examined daily level variations of serum lipids (NEFA, triglycerides, phospholipids, total cholesterol and total lipids) in healthy dogs, particularly focusing on their temporal relationship to lighting and fasting cycles. While serum NEFA levels did not change across the day, we showed daily variations in levels of total lipids, total cholesterol, phospholipids, and triglycerides in dogs maintained under 12L:12D cycles and fed a single meal in the day. Interestingly, only the rhythmic pattern of triglycerides respond to a shift of the 12L:12D cycle suggesting a cardinal role of a light-entrained circadian oscillator in its generation. To investigate whether temporal variations in serum lipids depend to physiological post-prandial changes, we measured lipid levels in fasted dogs. Rhythms of total lipids, total cholesterol, phospholipids, and triglycerides vanished when dogs were food deprived indicating that these rhythms are driven by the digestive process. The serum NEFA pattern in fasted dogs had a different trend: levels were significantly high during fasting than after food intake. The increase of NEFA concentrations during fasting may reflect the adipose tissue NEFA mobilization mediated by the decrease in insulin with its lypolitic effects. To know the existence of daily lipid rhythmicity is a fundamental necessity to understand the metabolism of the dog, an animal model frequently used for research in metabolic pathophysiology
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Daily rhythmicity of core and surface temperatures of sheep kept under thermoneutrality or in the cold
No full textWe compared the daily rhythms of body core temperature and surface temperature in 10 Comisana ewes housed at thermoneutrality (25 °C) and in the cold (9 °C). Core temperature was measured with a rectal probe, whereas surface temperature (in the eye, forehead, and foot) was measured by infrared thermog- raphy, at 3 h intervals for 27 consecutive hours under each condition. We found a robust rhythm of core temperature, whose amplitude doubled from 0.2 °C at thermoneutrality to 0.4 °C in the cold. The surface temperatures were all lower than core temperature and exhibited weaker but significant daily rhythmic- ity. At thermoneutrality, foot temperature (an indicator of vasodilation in the service of heat loss) peaked 3 h before rectal temperature. Studies on other species are needed to clarify whether the latency between the peaks of the oscillations in foot and core temperature vary in a species-specific manner and are responsible for the generation of the core temperature rhythm
Daily rhythmicity of circulating melatonin is not endogenously generated in the horse
No full textMelatonin secretion exhibits daily rhythmicity in many vertebrate species. In mammals, the rhythmicity is believed to result from two related processes: inhibition of pineal activity by environmental light during the day and stimulation of pineal activity by the master circadian clock at night. While circadian modulation of melatonin secretion under constant environmental conditions has been documented in numerous mammalian species, no extensive survey has been conducted. In this study, we investigated daily/circadian rhythmicity of plasma melatonin concentration, as well as of body temperature and of plasma sodium concentration, in horses maintained under a light-dark cycle and in extended darkness. All three variables exhibited robust 24-h rhythmicity under the light- dark cycle. Whereas rhythmicity of body temperature and sodium concentration persisted in extended darkness, rhythmicity of melatonin concentration did not. These findings strongly suggest that melatonin secretion in the horse is not under circadian control and is modulated only by environmental light
Circadian intraocular pressure rhythms in athletic horses under different lighting regime
No full textThe present study was undertaken to investigate the existence of intraocular pressure (IOP) rhythms in athletic thoroughbred horses maintained under a 24 h cycle of light and darkness (LD) or under constant light (LL) or constant dark (DD) conditions. We identified an IOP circadian rhythm that is entrained to the 24 h LD cycle. IOP was low during the dark phase and high during the light phase, with a peak at the end of the light phase (ZT10). The circadian rhythm of IOP persisted in DD (with a peak at CT9.5), demonstrating an endogenous component in IOP rhythm. As previously shown in other mammalian species, horse IOP circadian rhythmicity was abolished in LL. Because tonometry is performed in horses for the diagnosis of ophthalmologic diseases, such as glaucoma or anterior uveitis, the daily variation in IOP must be taken into account in clinical practice to properly time tests and to interpret clinical findings
Metabolic changes in dairy cows at different lactation class during the transition period
No full textModification of some haematological and haematochemical parameters in horse during long distance rides.
No full textThe aim of this study was to evaluated the effect of the low-intensity long-lasting trial on some haematological and haematochemical parameters during an international endurance race. Six clinically healthy and regularly trained Sella Italiana mares were used. On blood sample collected at rest, at 30 km, and 30’ after the trial, haematological (Red Blood Cell, Haemoglobin, Haematocrit; Mean Corpuscolar Volume, Mean Corpuscolar Hemoglobin, Mean Corpuscolar Hemoglobin Concentration, White Blood Cell and Platelets), and haematochemical parameters (Glucose, Aspartate aminotransferase, Total protein and protein fraction (albumin, α1-globulins, α2-globulins, β-globulins and γ-globulins), Triglycerydes, Cholesterol, Creatinine, Urea, Potassium, Sodium and Chloride) were assessed. One way repeated ANOVA showed a statistical significant effect of low-intensity long-lasting trials on the following parameters: Red Blood Cell (p≤0.009), Haematocrit (p≤0.031), Mean Corpuscolar Hemoglobin Concentration (p≤0.013), White Blood Cell (p<0.0001), Platelets (p<0.0001), α1-globulins (p≤0.038) and γ-globulins (p≤0.009), Creatinine (p≤0.023) and Potassium (p≤0.012). Our results confirm the effects of endurance trial on horse metabolism, underlining that haematological and haematochemical profiles could be an useful index for the prevention of many typical diseases of the athlete horse other than in the assessment of the fitness of the endurance horse
Food anticipatory activity e ritmi giornalieri di alcuni parametri fisiologici nella pecora e nel cavallo
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