Circulating amino acids in blood plasma during the peripartal period in dairy cows with different liver functionality index.

The liver functionality index (LFI) measures the changes of albumin, cholesterol, and bilirubin concentrations between 3 and 28 d postpartum. This composite index, based on variables with direct relevance to liver-specific plasma protein synthesis (albumin), hepatic/intestinal lipoprotein synthesis (cholesterol), and clearance of breakdown products of heme catabolism (bilirubin), provides a tool for evaluating manifestations of hepatic disease. Both energy and protein metabolism are likely to be affected by various physiological challenges in this period but have not been tested systematically. The present study was conducted to profile AA in cows with high or low LFI during the peripartal period and relate this to production outcomes. Eighteen multiparous cows were used from -21 through 28 d around parturition and divided retrospectively into the high or low LFI group. Blood samples were obtained on -21, -14, -7, 1, 3, 7, 10, 14, 17, 21, and 28 d relative to calving, and biomarkers and AA in plasma were measured. Grouping based on LFI resulted in 8 cows with high LFI (HLFI) and 10 cows with low LFI (LLFI). Although the temporal response in dry matter intake (DMI, 16.3 kg/d) and body condition score (2.56) did not differ, cows with high compared with low LFI had greater overall milk production (37.9 vs. 32.9 kg/d) although energy-corrected milk yield did not differ (42.6 vs. 38.7 kg/d). As expected, cows grouped as LLFI had lower cholesterol and albumin but greater bilirubin after calving compared with HLFI animals. Despite similar temporal responses in DMI between groups, concentrations of total AA were greater in HLFI, particularly after calving. Although concentrations of total essential AA (EAA) and branched-chain AA did not differ with LFI status, cows in HLFI had greater concentrations of Thr and Ile postpartum. Nearly all plasma AA concentrations followed the general trend of a nadir at 1d after calving followed by a gradual increase to prepartal levels before 28 d. Glycine was the only AA exhibiting a gradual increase in concentration through the transition, with a maximum at 7d postpartum followed by a gradual decrease. We detected no effect of LFI status on plasma Lys, which decreased markedly from -21d to calving, followed by an increase to prepartal values by d7. In contrast, concentrations of Met and His decreased markedly between -21 and 10d and did not reach prepartal values by 28 d. The marked decrease in Gln concentration after calving regardless of LFI might compromise immune function during this period. Overall, the results indicate the existence of an association among inflammation, liver function postpartum, and AA plasma concentrations, irrespective of temporal differences in DMI. Cows with better indices of liver function produced more milk and maintained greater concentrations of total AA and some EAA such as Thr and Ile. Whether these AA played a direct role in the greater milk production remains to be determined.

Experience from the Argentine Pegvisomant Observational Study: preliminary data.

The GH receptor antagonist pegvisomant is an efficient agent to achieve biochemical control of acromegaly in those cases refractory to surgery and medical therapy with somatostatin analogs. We conducted an observational multicenter study consisting of data collection in accordance with the standard management of patients with acromegaly in everyday practice. We reviewed the medical records of 28 patients, 23 females, who were treated with pegvisomant due to the lack of biochemical response or intolerance to the somatostatin analogs. The objective was to monitor long-term safety and efficacy of the antagonist. 82% of the patients had previous pituitary surgery, 53.6% radiotherapy and 96.4% received medical therapy for acromegaly. Only 19.2% of the patients had pituitary residual tumor size larger than 1 cm, the remainder harbored a microadenoma or no visible tumor in the pituitary images. In terms of biochemical efficacy, IGF-I levels decreased to normal ranges in 45% and 58.8% of patients after 3 and 6 months of treatment, respectively, the daily mean dose of pegvisomant being 9.6+/-1.1 mg. Adverse events, potentially related to pegvisomant were reported in 6 patients (21.4%), local injection site reaction and elevated liver enzymes being the most frequent. Tumor size did not show enlargement in the evaluated population (15 patients) during the period of the study. This paper presents preliminary data from a small observational study in Argentina which represents the first database in our country.

Plasma paraoxonase, health, inflammatory conditions, and liver function in transition dairy cows.

Paraoxonase (PON) is a liver protein with hydrolase activity that is released into the blood stream. Paraoxonase may serve as an index of liver function because it is drastically reduced in chronic liver damage. Sixty-seven periparturient dairy cows were used to evaluate the relationship between plasma PON, health problems, inflammatory conditions, and liver function. Baseline plasma PON concentrations during the first 30 d in milk (DIM) were retrospectively used to group cows into quartiles. Metabolic profile, lipid metabolites (e.g., nonesterified fatty acids, beta-hydroxybutyrate), inflammatory indices (haptoglobin, ceruloplasmin), low and high density lipoprotein cholesterol, vitamin A, vitamin E, reactive oxygen metabolites, total antioxidants, and PON in plasma were measured 2 wk before to 8 wk after calving. Weekly milk yield, body condition score, and all health problems were recorded. After parturition (7 DIM), cows in the lower PON group had the lowest plasma concentrations of negative acute phase proteins compared with the higher PON group for retinol binding protein (23.2 +/- 2.86 vs. 36.0 +/- 2.96 microg/dL of vitamin A), albumin (31.6 +/- 0.73 vs. 33.9 +/- 0.75 g/L), total cholesterol (2.04 +/- 0.30 vs. 2.45 +/- 0.42 mmol/L), and the highest concentrations of haptoglobin (0.67 vs. 0.24 +/- 0.03 g/L; positive acute phase protein) and globulins (37.2 vs. 32.3 +/- 1.4 g/L). Plasma bilirubin was highest in the cows (10.1 vs. 6.2 +/- 0.6 micromol/L) in the lowest PON quartile. Plasma PON was negatively correlated with haptoglobin (r = -0.39) and bilirubin (r = -0.42) and positively correlated with retinol binding protein (r = 0.54), albumin (r = 0.38), and cholesterol (r = 0.55) fractions. A total of 82.3% of cows in the lower quartile and no cows in the upper quartile experienced serious inflammation. Lower quartile cows produced 28.1 +/- 10.3 kg of milk/d; whereas upper quartile cows produced 38.3 +/- 7.7 kg of milk/d during the first 30 DIM. A reduction in the ability of the liver to cope with the increased metabolic demand near parturition in dairy cows can be diagnosed using changes in baseline plasma PON.