Influence of Body Condition on Serum Metabolic Indicators of Lipid Mobilization and Oxidative Stress in Dairy Cows During the Transition Period.

The objectives of this study were to examine the influence of body condition of cows on metabolic and antioxidative status, as well as to investigate the relationship between metabolic indicators of lipid mobilization and oxidative stress during transition period. The study was conducted on 24 Holstein-Friesian dairy cows divided into 2 groups according to their body condition score (BCS) as optimal (n = 12; BCS from 3.25 to 3.75) or adipose (n = 12; BCS ≥4). Metabolic status (glucose, triglycerides, total cholesterol, HDL cholesterol, NEFA and BHB), paraoxonase-1 (PON1) and apolipoprotein A-I (ApoA-I) were analysed in sera taken on days -30, -10, -2, 0, 5, 12, 19, 26 and 60 relative to parturition. Adipose cows had significantly higher glucose concentration at parturition being significantly decreased after parturition on days 12 and 19. Total cholesterol and HDL-C concentrations were the lowest at parturition and significantly higher on days 26 and 60 after parturition in both groups of cows. Both investigated groups had significantly higher NEFA concentration from parturition until day 19 after parturition, indicating energy deficit and an increased lipid mobilization after calving. There were no significant differences in BHB concentration during transition period in both groups. No significant differences were found in PON1 activity and ApoA-I concentration during transition period in both groups of cows. However, in adipose cows, although not significantly different, PON1 was decreased from calving until day 19 after parturition indicating a disturbance in antioxidative status in adipose cows. PON1 significantly positively correlated with total cholesterol and HDL-C concentrations and negatively with NEFA indicating a strong relationship of PON1 with lipid metabolism. Significant positive correlation between NEFA and BHB in both groups of cows points out on energy deficit during transition period that cows tend to overcome by lipid mobilization providing alternative source of energy needed for parturition and lactation.

The Effect of Seasonal Thermal Stress on Lipid Mobilisation, Antioxidant Status and Reproductive Performance in Dairy Cows.

Heat stress is a major factor contributing to low fertility of dairy cows with a great economic impact in dairy industry. Heat-stressed dairy cows usually have reduced nutrient intake, resulting in a higher degree of negative energy balance (NEB). The aim of this study was to investigate the seasonal thermal effect on lipid metabolism, antioxidant activity and reproductive performance in dairy cows. Thirty-two healthy dairy heifers were included in the study. According to the ambient temperature, animals were divided into two groups: winter (N = 14) and summer season (N = 18). Metabolic parameters, paraoxonase-1 (PON1) activity and total antioxidant status (TAS) were monitored at the time of insemination (basal values) and from 1 week before until 8 weeks after calving. Number of services per conception and calving-to-conception (CC) interval were calculated from the farm recording data. Serum triglyceride, non-esterified fatty acids (NEFA) and beta-hydroxybutyrate (BHB) concentrations were significantly increased after calving in summer compared to winter, indicating higher degree of NEB in cows during summer. PON1 activity was significantly decreased after calving in both summer and winter group. TAS concentration was significantly lower in summer than that in winter. A significantly higher number of services were needed for conception in summer compared to winter, and CC interval was significantly longer in summer than that in winter as well. Additionally, reproductive performance significantly correlated with the severity of NEB, suggesting that lipid mobilization and lower antioxidant status contributed to poor reproduction ability in dairy cows during hot months.

Lipid mobilisation and oxidative stress as metabolic adaptation processes in dairy heifers during transition period.

The objective of this study was to evaluate metabolic disorders and oxidative stress in dairy heifers during the transition period. Possible relationships between lipid mobilisation indicators and oxidative stress markers were investigated as well. Nineteen dairy heifers were included in the study. Blood samples were collected at the time of estrus synchronisation in heifers, at insemination, three weeks after insemination, one week before calving, at calving and 1, 2, 4 and 8 weeks postpartum. Common metabolic parameters, beta-hydroxybutyrate (BHB), free fatty acids (FFA), paraoxonase-1 (PON1) activity and total antioxidative status (TAS) were analysed. Around insemination, no significant difference was observed in the majority of tested parameters (P>0.05). However, the transition period markedly affected the concentration of triglycerides, total cholesterol, HDL-C, BHB, FFA, TAS and PON1activity. Positive correlations between PON1 activity and total cholesterol, HDL-C and triglycerides were noted but inverse correlations with FFA, BHB and bilirubin were found indicating that PON1 activity changed with lipid metabolism and was influenced by negative energy balance. These findings suggest that lipid mobilisation and oxidative stress are part of a complex metabolic adaptation to low energy balance which reaches equilibrium later in advanced lactation.

Influence of oxidative stress and metabolic adaptation on PON1 activity and MDA level in transition dairy cows.

Serum PON1 is a HDL-associated enzyme that protects lipoproteins, both LDL and HDL, against oxidation and it is considered as an antioxidative/anti-inflammatory component of HDL. Dairy cows are highly susceptible to oxidative stress which commonly occurs in late pregnancy and early lactation. During the transition period, increased production of reactive oxygen species is associated to processes of metabolic adaptation to a low-energy balance. We investigated serum paraoxonase-1 (PON1) activity and malondialdehyde (MDA) concentration to assess the antioxidative/prooxidative status during pregnancy and the postpartum period. In order to evaluate metabolic homeostasis, common metabolic parameters (glucose, triglyceride, total cholesterol, HDL-C and albumin concentrations) were determined as well. A significantly lower PON1 activity was found in late pregnancy and early postpartum (P<0.05) compared to the first and the second trimester of pregnancy and the mid-lactation. MDA level was significantly higher (P<0.05) in the dry period compared to pregnant lactating and postpartum cows. Serum glucose concentration (P<0.001) was lower in the early and late puerperium indicating low-energy balance in the early lactation. Serum triglyceride and albumin concentrations were lower in late puerperium (P<0.001), while total cholesterol and HDL-C were lower during the dry period (P<0.05) as well as in early postpartum (P<0.001). Significant correlations of PON1 activity with glucose (P<0.05), albumin (P<0.05), total cholesterol (P<0.001) and HDL-C (P<0.001) were also found. The observed lower serum PON1 activity and higher MDA level in late pregnancy and early postpartum could indicate a prooxidants/antioxidants imbalance influenced by reproductive stress and metabolic adaptation in the transition period of dairy cows.

The effect of the zeolite clinoptilolite on serum chemistry and hematopoiesis in mice.

Zeolites are natural or synthetic crystalline alumosilicates with ion exchanging properties. Supplied in fodder, they promote biomass production and animal health. Our aim was to assess the effects of the natural zeolite, clinoptilolite, on hematopoiesis, serum electrolytes and essential biochemical indicators of kidney and liver function in mice. Two preparations differing in particle size were tested: a powderized form obtained by countercurrent mechanical treatment of the clinoptilolite (MTCp) and normally ground clinoptilolite (NGCp). Young adult mice were supplied with food containing 12.5, 25 or 50% clinoptilolite powder. Control animals received the same food ration without the clinoptilolite. After 10, 20, 30 and 40 days, six animals from each group were exsanguinated to obtain blood for hematological and serum for biochemical measurements as well as to collect femoral bone marrow for determination of hematopoietic activity. Clinoptilolite ingestion was well tolerated, as judged by comparable body masses of treated and control animals. A 20% increase of the potassium level was detected in mice receiving the zeolite-rich diet, without other changes in serum chemistry. Erythrocyte, hemoglobin and platelet levels in peripheral blood were not materially affected. NGCp caused leukocytosis, with concomitant decline of the GM-CFU content in the bone marrow, which was attributed to intestinal irritation by rough zeolite particles. The mechanically treated clinoptilolite preparation caused similar, albeit less pronounced, changes. In a limited experiment, mice having transplanted mammary carcinoma in the terminal stage showed increased potassium and decreased sodium and chloride levels, severe anemia and leukocytosis, decreased bone marrow cellularity and diminished content of hematopoietic progenitor cells in the marrow. The clinoptilolite preparations ameliorated the sodium and chloride decline, whereas the effects on hematopoiesis were erratic.

Haematological profile in healthy urban population (8 to 70 years of age).

Haematological profile for 17 constituents of blood were determined in 998 healthy school children (8-19 years old) and 2246 healthy adult persons (20-70 years old) residing permanently or at least 5 years in a defined geographic region of Zagreb, Croatia. Physiological variations corresponding to age and sex were studied as the most important factors affecting biological variation in haematological constituents of blood. In our study erythrocytes, haemoglobin and haematocrit values were not sex dependent until the age of 13 after which the values were higher in men that in women. Sedimentation rate showed sex and age related differences in the adult age with higher values in women especially after 50 years. Total leukocyte count declined with age and in adults the values were slightly lower in women. Segmented neutrophil granulocytes showed the upward trend with age whereas the lymphocyte and monocyte counts declined. Women showed slightly higher platelet count in the adult age. Based on biological variation, we have estimated the reference intervals for 17 haematological constituents of blood in order to provide medically reliable evaluation of haematological laboratory results.

External quality assessment in clinical chemistry: review of the situation in Croatia with particular reference to equipment.

The effect of the use of new flame photometers (Ciba Corning 480, Chiron, Salzburg, Austria) and multichannel analyzers (BM Hitachi 904 or BM Hitachi 911, both Boehringer GmbH, Mannheim, Germany) on analytical quality was assessed in a number of medical biochemical laboratories (n=58) at health centers and general hospitals that provide primary health care services for the respective catchment areas. The laboratories were supplied during 1996 and 1997 with new equipment, as part of the First Croatian Health Project, Primary Health Care Subproject, carried out by the Croatian Ministry of Health and Croatian Institute of Health Insurance. We evaluated analytical performance of these laboratories for 19 analytes, according to the results reported in the Croatian External Quality Assessment Program for medical biochemical laboratories, performed four times per year. Changes of percentages of particular methods used by the participating laboratories were observed for inorganic phosphate, total bilirubin, urea and creatinine. Such changes were even more pronounced for enzymes, where changes in the measurement procedure such as incubation temperature and buffers were observed in the methods used. Evaluation of method performance revealed that after the introduction of new equipment interlaboratory variation decreased, so that an increasing proportion of laboratories included in the Project produced results within the target limits.

Biological variations of human serum butyrylcholinesterase activity in a population from Zagreb, Croatia.

Biological variations of total butyrylcholinesterase activity (EC 3.1.1.8) in sera were determined in 993 healthy school children (age 8-19 years) and 2246 healthy adults (20-70 years) in a population from Zagreb, Croatia. Physiological variations corresponding to age and sex and genetically determined changes were studied as the important factors affecting biological variation in total butyrylcholinesterase activity. Based on biological variability, using a non-parametric statistical method, reference intervals for total butyrylcholinesterase activity were produced in order to provide medically reliable evaluation of laboratory results by pediatricians and clinicians in our country.

Lipoprotein (a) concentrations in school children and adolescents in Croatia.

Lipoprotein (a) concentrations in sera were determined on 536 healthy reference children and adolescents aged 8-19 years from Zagreb, Croatia. The frequency distribution showed that 20.4% boys and girls had lipoprotein (a) concentrations above 0.3 g/L what is considered as a cut-off value for the increased risk of early atherosclerosis. The results of correlation studies and factor analysis support the concept that the concentrations of lipoprotein (a) could be an independent risk factor and therefore may have a great value in the prediction of atherosclerosis early in life.

[Biologic variation in electrolytes and essential microelements in the blood of neonates and their mothers]. / Bioloska varijacija elektrolita i esencijalnih mikroelemenata u serumu zdrave novorodencadi i njihovih majki.

Serum concentration and biological variability (CVB%) of total calcium (Ca) magnesium (Mg), iron (Fe), zinc (Zn) and copper (Cu) were determined in 22 sera of maternal and umbilical cord blood in normal pregnancies. The concentrations of Ca (2.48 +/- 0.13 vs 2.27 +/- 0.13 mmol/l), Mg (0.84 +/- 0.06 vs 0.80 +/- 0.07 mmol/l), Fe (24.1 +/- 6.62 vs 10.7 +/- 4.94 mumol/l) and Zn (14.1 +/- 1.78 vs 9.1 +/- 2.21 mumol/l) in the cord sera were significantly higher than in maternal sera (p < 0.01), whereas maternal copper concentrations (36.6 +/- 4.82 vs 9.2 +/- 2.21 mumol/l), were significantly higher than in cord sera (p < 0.01). Biological variability of Ca (5.37 vs 4.84%), Mg (8.39 vs 6.69%), Fe (46.1 vs 27.3%) and Zn (24.1 vs 12.3%) values was higher in the maternal sera than the respective values in the cord sera, while the biological variability of copper in the cord sera was significantly higher than the respective value in the maternal sera (26.7 vs 12.8%). These results are in agreement with those previously reported and suggest that fetal homeostasis of Ca, Mg, Fe and Zn is at least partly independent of maternal factors.

Pediatric reference intervals for 34 biochemical analytes in urban school children and adolescents.

Concentrations of 34 biochemical constituents of sera were determined on 998 randomly selected urban school children and adolescents aged 8-18 years from Zagreb, Croatia. Reference intervals were obtained by using non-parametric methods to estimate 2.5 and 97.5 percentiles of distribution as upper and lower normal reference intervals, according to the IFCC recommendations. These were compared to reference intervals in the healthy adult population, aged 20-30 years from the same geographical area. Serum glucose, potassium, sodium, chloride, magnesium, iron, zinc, total serum proteins and electrophoretic fractions, and amylase, did not show age or sex differences; total serum bilirubin, total calcium, phosphate, high density lipoprotein cholesterol, total iron binding capacity, unsaturated iron binding capacity, copper, aspartate aminotransferase, alkaline phosphatase, cholinesterase, creatine kinase, and lactate dehydrogenase had higher reference intervals than the adult population. Urea, creatinine, urate, alanine aminotransferase, gamma-glutamyltransferase, total cholesterol and low density lipoprotein-cholesterol, and triglycerides had lower reference intervals than the adult population.

Validity of 5-aminolevulinate dehydratase activity (5-ALAD) for the discrimination of alcoholics and nonalcoholics with chronic liver disease.

Alcohol consumption decreases erythrocyte 5-ALAD activity. Our aim was to assess the diagnostic value of 5-ALAD in discriminating alcoholics from nonalcoholics among patients with chronic liver disease and to find the combination of 5-ALAD and other clinical chemical tests that best differentiates these two groups. Measurements of erythrocyte 5-ALAD activity by fluorometry and 10 other biochemical tests were performed in 205 subjects with biopsy-verified liver damage (88 alcoholics, 117 nonalcoholics). The highest six Chi-square (chi 2) test values out of the 11 tests performed were diagnostically evaluated individually and in combinations of two to five tests, according to the number of positive findings. Our results show that 5-ALAD provides the highest efficiency as an individual test, while combinations of three tests where 5-ALAD is involved, especially the combination of 5-ALAD, gamma-glutamyltransferase and mean corpuscular volume of erythrocytes, seem to be the best test combinations for discriminating alcoholics from nonalcoholics among patients with chronic liver diseases.