Amino Acid Infusion Research Articles

Amino acids and the kidney; friends or foes?

Acute kidney injury (AKI) is common in hospitalized patients and is independently associated with morbidity and mortality. Moreover, AKI increases the risk of chronic kidney disease, which is a major healthcare problem. Currently, no single therapy has been proven to be effective in preventing AKI. The role of amino acids in the context of kidney function and AKI prevention has been controversial and most of the evidence is available from nutritional studies. However, knowledge of amino acids in recruiting renal functional reserve and their potential role to protect renal function under stress has recently expanded. The nephroprotective effects of amino acids were first postulated in 1973. Recently, this strategy gained renewed interest and has been more extensively studied, reintroducing their use in clinical situations characterized by a high incidence of AKI. Intravenous amino acids administration for kidney protection is now supported by a large multinational randomized double-blind controlled trial in cardiac surgery and by experimental and observational data. All such data support the rationale for a biologically and clinically important nephroprotective effect. The infusion of amino acids was recently found to reduce the incidence of AKI in cardiac surgery patients and surgical patients. This strategy for the protection of renal function is supported by a multicenter, international, double-blind randomized trial, with a huge potential for additional application in several clinical fields. Several mechanisms of action support the robustness of these findings and are summarized in this manuscript.

Comparison of Nutritional Outcomes between Different Techniques of Intradialytic Amino Acid Infusion in Patients on Hemodialysis: A Randomized Controlled Trial

Comparison of Nutritional Outcomes between Different Techniques of Intradialytic Amino Acid Infusion in Patients on Hemodialysis: A Randomized Controlled Trial

A Prospective Study on Role of IV Amino Acid Infusion in Improving Pregnancy Outcome in Cases of Oligohydramnios

A Prospective Study on Role of IV Amino Acid Infusion in Improving Pregnancy Outcome in Cases of Oligohydramnios

Does amino acid infusion improve kidney outcomes in patients at high risk for postsurgical AKI?

Does amino acid infusion improve kidney outcomes in patients at high risk for postsurgical AKI?

Dosimetric implications of kidney anatomical volume changes in 177Lu-DOTATATE therapy

IntroductionThis study aims to evaluate the use of CT-based whole kidney parenchyma (WKP) segmentation in 177Lu-DOTATATE dosimetry. Specifically, it investigates whether WKP volumes change during treatment and evaluates the accuracy of applying a single delineated WKP volume for dosimetry. Furthermore, it aims to determine the cause of WKP volume changes—whether caused by radiation or amino acid infusion—by comparing them with spleen volume changes as a marker for radiation-induced alterations.MethodsSPECT/CT images of 18 patients were acquired over the abdomen approximately 4 h (h) (D0), 24 h (D1), 48 h (D2) and 168 h (D7) post-administration of 177Lu-DOTATATE. CT guided WKP volumes were measured before (baseline) and during treatment. Kidney activity concentrations at each time point were derived from CT-segmented WKP overlaid on SPECT scans. The accuracy of using WKP segmentation from a single CT for all time points was assessed against the gold standard of segmenting each WKP individually. Time-integrated activity calculations were based on a tri-exponential curve fit of the kidney activity concentration over time. Kidney absorbed doses were estimated under the assumption of local energy deposition. Additionally, the impact of various partial volume correction methods on dosimetry was evaluated.ResultsWhole-kidney parenchyma (WKP) volumes, ranging from 31 to 243 mL, showed a gradual increase from baseline (mean ± SD = 130.6 ± 46.1 mL) at the initial time points D0 (138.5 ± 44.7 mL) and D1 (139.4 ± 41.6 mL), followed by a slight decrease at D2 (132.8 ± 44.5 mL) and a further decrease at D7 (129.2 ± 42.7 mL). The volume increase at D0 and D1 was statistically significant. Spleen volume did not change during treatment, suggesting that amino acid infusion rather than irradiation effects caused WKP volume changes. Bland-Altman analysis revealed WKP volume biases of 8.77% (D0 vs. BL), 10.77% (D1 vs. BL), 1.10% (D2 vs. BL), and 1.10% (D7 vs. BL), with corresponding uncertainties of 24.4%, 23.6%, 25.4%, and 25.4%, respectively. When WKP segmentation from a single CT is applied across all SPECTs, these WKP volume changes could overestimate the activity concentration and mean absorbed doses up to 4.3% and 2.5%, respectively. The absorbed dose uncertainties using a recovery coefficient (RC) of 0.85 for single-time-point WKP delineation increase the absorbed dose uncertainty by 4% compared to the use of patient-specific RCs and time specific segmentation of WKP volumes.ConclusionsKidney volume exhibited significant variation form D0 to D7, affecting the precision of dosimetry calculation, primarily due to errors in whole-kidney parenchyma (WKP) delineation. Notably, using WKP segmentation from a single CT scan applied to sequential SPECT images introduce further uncertainty and may lead to an overestimation of the absorbed dose. The fluctuations in kidney volume are most likely attributable to amino acid infusion.

Amino Acid Infusion for Perioperative Functional Renal Protection: A Meta-analysis

ObjectiveAcute kidney injury (AKI) is a common perioperative complication. To date, no single intervention has been proven effective for AKI prevention in this setting. However, intravenous amino acids (AA) administration may recruit renal functional reserve and, thereby, attenuate the perioperative loss of glomerular filtration rate. Accordingly, we performed a meta-analysis to assess the efficacy of AA infusion for perioperative renal functional protection. MethodsWe performed a meta-analysis of controlled studies in perioperative patients (P) evaluating intravenous AA infusion (I) versus any comparator (C). The primary outcome was AKI at longest follow-up (O). We performed a random effects meta-analysis on the relative risk (RR) scale to assess the effect of AA infusion. We used a Bayesian approach to estimate the probability of benefit (RR<1) for the primary outcome. Secondary outcomes included renal-replacement therapy, serum creatinine, and estimated glomerular filtration rate. Tertiary outcomes included mechanical ventilation duration, intensive care unit and hospital length of stay and mortality. (PROSPERO: CRD42024547225). ResultsWe identified 15 studies (14 RCTs and one prospective before-after study) reporting at least one outcome of interest (4,544 patients), with six studies (4,084 patients) reporting the primary outcome. AKI occurred 504/2,041 (24.7%) in AA patients vs 614/2,041 (30.1%) in controls (RR=0.66; 95% CI, 0.47 to 0.94; I2=50%; p=0.02), which corresponded to a 99.1% probability of AKI reduction with AA. Moreover, coherent with such findings, AA reduced serum creatinine, and hospital length of stay, and increased eGFR. ConclusionsThis meta-analysis suggests that AA administration likely reduces the perioperative incidence of AKI.

Glucagon Resistance in Individuals With Obesity and Hepatic Steatosis Can Be Measured Using the GLUSENTIC Test and Index.

Increased plasma levels of glucagon (hyperglucagonaemia) promote diabetes development but is also observed in patients with metabolic dysfunction-associated steatotic liver disease (MASLD). This may reflect hepatic glucagon resistance towards amino acid catabolism. A clinical test for measuring glucagon resistance has not been validated. We evaluated our glucagon sensitivity (GLUSENTIC) test, consisting of two study days: a glucagon injection and measurements of plasma amino acids, and an infusion of mixed amino acids and subsequent calculation of the GLUSENTIC index (primary outcome measure) from measurements of glucagon and amino acids. To distinguish glucagon-dependent from insulin-dependent actions on amino acid metabolism, we also studied patients with type 1 diabetes (T1D). The delta-decline in total amino acids was 49% lower in MASLD following exogenous glucagon (p=0.01), and the calculated GLUSENTIC index was 34% lower in MASLD (p<0.0001), but not T1D (p>0.99). In contrast, glucagon-induced glucose increments were similar in controls and MASLD (p=0.41). The GLUSENTIC test and index may be used to measure glucagon resistance in individuals with obesity and MASLD.

Effects of abomasal infusion of branched-chain amino acids or branched-chain keto-acids on liver function, inflammation, and oxidative stress in multiparous fresh cows

Reduced liver function, increased oxidative stress, and inflammation in early lactation negatively impact lactation performance and health of fresh cows. Previous findings from our group demonstrated that branched-chain amino acids (BCAA) infusion improved lactation performance and branched-chain ketoacids (BCKA) infusion decreased liver triglyceride (TG) in fresh cows. The objectives of this study were to determine the effect of BCAA and BCKA on blood and liver biomarkers of liver function, oxidative stress, and inflammation as well as expression of genes regulating inflammation and antioxidant metabolism in the liver. Thirty multiparous Holstein cows were used in a randomized block design receiving continuous abomasal infusion for 21 d after parturition. Treatments (10 cows each) were control (CON), cows abomasally infused with 0.9% saline; BCA, cows abomasally infused with BCAA (67 g valine, 50 g leucine, and 34 g isoleucine); and BCK, cows abomasally infused with BCKA (77 g ketovaline, 57 g ketoleucine, and 39 g ketoisoleucine). All cows were randomly assigned to treatments after parturition and received the same diet throughout the experimental period. Blood was collected at 3, 7, 14, and 21 d postpartum for liver function, oxidative stress, and inflammation biomarker profiling. Liver was also harvested on 7, 14, and 21 d postpartum for quantification of glutathione, protein carbonylation, and expression of genes. ANOVA was conducted for all data using PROC GLIMMIX in SAS. No treatment differences were observed for liver function biomarkers (bilirubin, gamma-glutamyl transferase, and aspartate aminotransferase). Cows receiving BCAA had lower blood NO2- and NO3- concentrations compared with CON. A tendency for lower advanced oxidized protein products was also observed in BCA cows compared with CON. Additionally, on d 7, BCA cows had lower protein carbonylation in the liver compared with CON. In contrast, BCK cows had higher plasma thiol and albumin, as well as liver reduced and total glutathione compared with CON cows. Compared with CON, BCK cows had higher expression glutathione reductase in the liver. Overall, these results suggest favorable alterations in oxidative stress and inflammation status in fresh cows receiving BCAA or BCKA infusion during the first 3 weeks of lactation, which likely contributed to previously-observed changes in lactation performance and liver TG concentrations. Future work is required to evaluate the interrelated metabolism of BCAA and BCKA to better understand their effects on oxidative and immune metabolism.

Short-term parenteral infusions with high-osmolality amino acid solutions can be safely administered through peripheral catheters in dogs treated for hypoaminoacidemia-related conditions.

To compare complications between central and peripheral administration of high-osmolarity (approx 700 to 1,000 mOsm/L) amino acid (± lipid) infusions. 18 client-owned dogs diagnosed with aminoaciduric canine hypoaminoacidemic hepatopathy syndrome or superficial necrolytic dermatitis receiving parenteral amino acid ± lipid infusions. In this retrospective case series, medical records were reviewed for administration route (central vs peripheral), catheter details and infusion characteristics (product osmolarity, concurrent lipid administration, infusion volume, duration, and rate), and complications for each infusion. 18 dogs received 277 infusions (median, 8.5; range, 1 to 84). Effective infusion osmolarities were 683 mOsm/L in 22% of infusions, 791 mOsm/L in 8%, 802 mOsm/L in 2%, 837 mOsm/L in 45%, and 998 mOsm/L in 23% (65% peripheral, 35% central). Most (n = 230 [83%]) infusions were given peripherally. The osmolarities of solutions administered by each route (P = .53), the infusion rate indexed to body weight (P = .17), or the lipid infusion rates indexed to body weight (P = .89) did not differ. One dog suffered 2 complications in 63 infusions-1 mild, 1 severe-both occurring with peripheral infusions. Thus, the overall complication rate was 2 of 277 (0.9%) infusions. Short-term peripherally administered amino acid ± lipid infusions < 1,000 mOsm/L confer little risk compared to centrally administered infusions. Additional studies are needed to determine the safety of infusions with longer durations. Due to the relative ease of peripheral catheterization, clinicians should consider this route for medically managing aminoaciduric canine hypoaminoacidemic hepatopathy syndrome and superficial necrolytic dermatitis in dogs.

The physiological basis of renal nuclear medicine.

Renal physiology underpins renal nuclear medicine, both academic and clinical. Clearance, an important concept in renal physiology, comprises tissue uptake rate of tracer (tissue clearance), disappearance rate from plasma (plasma clearance), appearance rate in urine (urinary clearance) and disappearance rate from tissue. In clinical research, steady-state plasma clearances of para-amino-hippurate and inulin have been widely used to measure renal blood flow (RBF) and glomerular filtration rate (GFR), respectively. Routinely, GFR is measured at non-steady state as plasma clearance of a filtration agent, such as technetium-99m diethylenetriaminepentaacetic acid. Scaled to three-dimensional whole body metrics rather than body surface area, GFR in women is higher than in men but declines faster with age. Age-related decline is predominantly from nephron loss. Tubular function determines parenchymal transit time, which is important in renography, and the route of uptake of technetium-99m dimercaptosuccinic acid, which is via filtration. Resistance to flow is defined according to the pressure-flow relationship but in renography, only transit time can be measured, which, being equal to urine flow divided by collecting system volume, introduces further uncertainty because the volume is also unmeasurable. Tubuloglomerular feedback governs RBF and GFR, is regulated by the macula densa, mediated by adenosine and renin, and can be manipulated with proximal tubular sodium-glucose cotransporter-2 inhibitors. Other determinants of renal haemodynamics include prostaglandins, nitric oxide and dopamine, while protein meal and amino acid infusion are used to measure renal functional reserve. In conclusion, for measuring renal responses to exogenous agents, steady-state para-amino-hippurate and inulin clearances should be replaced with rubidium-82 and gallium-68 EDTA for measuring RBF and GFR.

A Randomized Trial of Intravenous Amino Acids for Kidney Protection.

Acute kidney injury (AKI) is a serious and common complication of cardiac surgery, for which reduced kidney perfusion is a key contributing factor. Intravenous amino acids increase kidney perfusion and recruit renal functional reserve. However, the efficacy of amino acids in reducing the occurrence of AKI after cardiac surgery is uncertain. In a multinational, double-blind trial, we randomly assigned adult patients who were scheduled to undergo cardiac surgery with cardiopulmonary bypass to receive an intravenous infusion of either a balanced mixture of amino acids, at a dose of 2 g per kilogram of ideal body weight per day, or placebo (Ringer's solution) for up to 3 days. The primary outcome was the occurrence of AKI, defined according to the Kidney Disease: Improving Global Outcomes creatinine criteria. Secondary outcomes included the severity of AKI, the use and duration of kidney-replacement therapy, and all-cause 30-day mortality. We recruited 3511 patients at 22 centers in three countries and assigned 1759 patients to the amino acid group and 1752 to the placebo group. AKI occurred in 474 patients (26.9%) in the amino acid group and in 555 (31.7%) in the placebo group (relative risk, 0.85; 95% confidence interval [CI], 0.77 to 0.94; P = 0.002). Stage 3 AKI occurred in 29 patients (1.6%) and 52 patients (3.0%), respectively (relative risk, 0.56; 95% CI, 0.35 to 0.87). Kidney-replacement therapy was used in 24 patients (1.4%) in the amino acid group and in 33 patients (1.9%) in the placebo group. There were no substantial differences between the two groups in other secondary outcomes or in adverse events. Among adult patients undergoing cardiac surgery, infusion of amino acids reduced the occurrence of AKI. (Funded by the Italian Ministry of Health; PROTECTION ClinicalTrials.gov number, NCT03709264.).

#2287 Impact of renal reserve before donation in post-transplant renal function of donors and recipients

Abstract Background and Aims The influence of Renal Reserve (RR), i.e. its presence or absence, in post-transplant renal function both in living kidney donors and recipients is unknown. The presence of RR in donors may be beneficial in terms of better renal function both for the donor and recipient after transplantation. In the other hand, the absence of RR in donors might indicate a lower renal endowment and so predispose to lower GFR post-transplantation in donors and recipients. However, little evidence is available in this field. Method In a previous study (ERA Abstract 2023, #3737) we described in a group of 52 potential living kidney donors, the presence (24-46%), absence (13-25%) or use (15-29%) of RR before donation. The latter was defined as the lack of increase in GFR after stimulation in patients with basal GFR &amp;gt; 100 mL/min. GFR was measured before and after transplantation by the clearance of iohexol with dried blood spots. Presence of RR was defined as an increase &amp;gt;10% of basal GFR after IV amino acid infusion. GFR was unadjusted to body surface area (BSA). In this follow-up study we investigated the impact of the presence, absence or use of RR before donation in GFR 12 months after transplantation, both in donors and recipients. Results Of the 52 pairs of donors and recipients, renal transplantation was performed in 21 who also had 12 months of follow-up. Before transplantation 9 donors had RR, 4 did not and 8 had RR in use. Pre-transplant GFR was 95 ± 15 ml/min, 89 ± 6 ml/min and 127 ± 16 ml/min in donors with RR, without RR and with RR in use, respectively. At 12 months after kidney donation, GFR was higher in donors who had RR in use before donation: 79 ± 12 ml/min, compared with those with RR: 65 ± 9 ml/min (p = 0.048) and those without RR 59 ± 10 (p = 0.03). In recipients, GFR was comparable between those who had a donor with RR or RR in use: 72 ± 19 ml/min vs 68 ± 12 ml/min (p = ns), whereas both groups had higher GFR than those recipients whose donors had no RR before donation 53 ± 5 ml/min, although of borderline signification (p = 0.07). Non parametric tests were used. No major complications after transplantations such as rejections or surgical complications, etc, that could alter GFR were observed. Conclusion The presence or use of RR may determine a better renal function 12 months after donation both for donors and recipients. This is a preliminary study and we acknowledge that the low number of cases is a limitation and so, these results require further studies.

Efficiency of succinylated gelatin and amino acid infusions for kidney uptake reduction of radiolabeled αvβ6-integrin targeting peptides: considerations on clinical safety profiles

Purpose68Ga-Trivehexin is an investigational PET radiopharmaceutical (NCT05799274) targeting αvβ6-integrin for PET imaging of carcinomas. 177Lu-D0301 is a structurally related therapeutic peptide tetramer. However, it showed considerable kidney uptake in rodents, impeding clinical applicability. We therefore evaluated the impact of different kidney protection strategies on the biodistribution of both agents in normal and tumor-bearing mice.MethodsEx-vivo biodistribution of 68Ga-Trivehexin (90 min p.i.) and 177Lu-D0301 (90 min and 24 h p.i.) was determined in healthy C57BL/6N and H2009 (human lung adenocarcinoma) xenografted CB17-SCID mice without and with co-infusion of 100 µL of solutions containing 2.5% arginine + 2.5% lysine (Arg/Lys), 4% succinylated gelatin (gelofusine, gelo), or combinations thereof. Arg/Lys was injected either i.p. 30 min before and after the radiopharmaceutical, or i.v. 2 min before the radiopharmaceutical. Gelo was administered either i.v. 2 min prior activity, or pre-mixed and injected together with the radiopharmaceutical (n = 5 per group). C57BL/6N mice were furthermore imaged by PET (90 min p.i.) and SPECT (24 h p.i.).ResultsKidney uptake of 68Ga-Trivehexin in C57BL/6N mice was reduced by 15% (Arg/Lys i.p.), 25% (Arg/Lys i.v.), and 70% (gelo i.v.), 90 min p.i., relative to control. 177Lu-D0301 kidney uptake was reduced by 2% (Arg/Lys i.p.), 41% (Arg/Lys i.v.), 61% (gelo i.v.) and 66% (gelo + Arg/Lys i.v.) 24 h p.i., compared to control. Combination of Arg/Lys and gelo provided no substantial benefit. Gelo furthermore reduced kidney uptake of 177Lu-D0301 by 76% (90 min p.i.) and 85% (24 h p.i.) in H2009 bearing SCID mice. Since tumor uptake was not (90 min p.i.) or only slightly reduced (15%, 24 h p.i.), the tumor/kidney ratio was improved by factors of 3.3 (90 min p.i.) and 2.6 (24 h p.i.). Reduction of kidney uptake was demonstrated by SPECT, which also showed that the remaining activity was located in the cortex.ConclusionsThe kidney uptake of both investigated radiopharmaceuticals was more efficiently reduced by gelofusine (61–85%) than Arg/Lys (25–41%). Gelofusine appears particularly suitable for reducing renal uptake of αvβ6-integrin targeted 177Lu-labeled peptide multimers because its application led to approximately three times higher tumor-to-kidney ratios. Since the incidence of severe adverse events (anaphylaxis) with succinylated gelatin products (reportedly 0.0062–0.038%) is comparable to that of gadolinium-based MRI or iodinated CT contrast agents (0.008% and 0.04%, respectively), clinical use of gelofusine during radioligand therapy appears feasible if similar risk management strategies as for contrast agents are applied.

Combination of Parenteral Amino Acid Infusion and Intermittent Loading Exercise Ameliorates Progression of Postoperative Sarcopenia in Rat Model.

Postoperative sarcopenia is associated with poor outcomes in hospitalized patients. However, few studies have focused on short-term postoperative sarcopenia. Furthermore, the influence of nutritional management using amino acids (AAs) comprising a peripheral parenteral nutrition (PPN) solution and its combination with exercise (Exc) is unclear. Hence, we established a postoperative sarcopenic rat model to evaluate the effects of parenteral AA infusion combined with Exc on skeletal muscles and investigate the underlying mechanisms involved in the amelioration of muscle atrophy. Male F344 rats underwent surgery followed by hindlimb suspension (HS) for 5 days. The rats were divided into AA (-), AA (+), AA (-)-Exc, and AA (+)-Exc groups. They were continuously administered a PPN solution with or without AA at 98 kcal/kg/day. The Exc groups were subjected to intermittent loading for 1 h per day. Postoperative sarcopenic rats exhibited decreased muscle strength and mass and an upregulated ubiquitin-proteasome system, autophagy-lysosome system, and fast-twitch fiber-related genes, especially in the AA (-) group. The AA (+)-Exc group exhibited attenuated decreased muscle strength, increased gastrocnemius mass, and a suppressed upregulation of muscle atrophy- and fast-twitch fiber-related genes. Therefore, parenteral AA infusion combined with Exc may be effective in preventing postoperative sarcopenia in hospitalized patients.

Fatal coinfection of blastocystosis and intestinal trichomoniasis in a rhesus macaque (Macaca mulatta).

A 3-year-old male rhesus macaque was presented at Referral Veterinary Polyclinic-Teaching Veterinary Clinical Complex, with a chief complaint of chronic diarrhoea and swelling of dependent body parts. The patient's history indicates that the monkey had been experiencing diarrhoea for the past month, with 2-3 episodes of vomiting in the last 2days. Additionally, oedema has developed within the last 2weeks. The clinical examination findings revealed dullness and depression, the mucus membrane appeared pale, with a temperature-102.1°F, a respiration rate-28/min, and a heart rate-92/min. The capillary refill time was 4s. During the physical examination, the animal exhibited oedema on the dependent part of the body and faecal staining around the perineum along with loose yellow stool. Direct saline and iodine mount faecal smear examination revealed the presence of many motile pear-shaped flagellated protozoa and round vacuolated Blastocystis organisms. Giemsa-stained faecal smear cytology confirmed the presence of Pentatrichomonas sp. and Blastocystis sp. along with many microbes. The faecal culture was negative for all pathogenic microbes. The case was diagnosed as co-infection Blastocystosis and intestinal trichomoniasis. The treatment was initiated with a combination of sulfamethoxazole + trimethoprim @ 35mg/kg body weight and metronidazole @25mg/kg administered orally once daily for 7days. Supportive therapy includes hematinic injection (iron sorbitol, folic acid and vitamin B12) @ 1ml total dose, administered intramuscularly on alternate days for four occasions as well as intravenous infusion of crystalline amino acid @ 5ml total dose on alternate days for four occasions. To manage vomition, injection ondansetron was administered@0.5mg/kg intramuscularly, twice daily for 3days and H2 blockers, including injection ranitidine@2mg/kg intramuscularly twice daily for 3days. Electrolyte and probiotic supplementation were administered orally. After 7days of therapy, the oedema had significantly improved and episodes of vomition were stopped but there was no significant improvement in the episode of diarrhoea and consistency of faeces. Unfortunately, on the 10th day of therapy, the animal suddenly collapsed. Understanding the virulence pattern of opportunistic protozoa in primates is crucial, and identifying suitable therapeutic candidates to prevent fatal outcomes is the need of the hour, especially considering protozoal infections as an important differential diagnosis in gastrointestinal tract-related ailments. Our study successfully demonstrated the co-occurrence of blastocystosis and intestinal trichomoniasis, both uncommon infections with potential zoonotic implications.

Abomasal infusion of branched-chain amino acids or branched-chain keto-acids alter lactation performance and liver triglycerides in fresh cows

BackgroundDairy cows are at high risk of fatty liver disease in early lactation, but current preventative measures are not always effective. Cows with fatty liver have lower circulating branched-chain amino acid (BCAA) concentrations whereas cows with high circulating BCAA levels have low liver triglyceride (TG). Our objective was to determine the impact of BCAA and their corresponding ketoacids (branched-chain ketoacids, BCKA) on production performance and liver TG accumulation in Holstein cows in the first 3 weeks postpartum.MethodsThirty-six multiparous Holstein cows were used in a randomized block design experiment. Cows were abomasally infused for the first 21 d postpartum with solutions of 1) saline (CON, n = 12); 2) BCA (67 g valine, 50 g leucine, and 34 g isoleucine, n = 12); and 3) BCK (77 g 2-ketovaline calcium salt, 57 g 2-ketoleucine calcium salt, and 39 g 2-ketoisoleucine calcium salt, n = 12). All cows received the same diet. Treatment effects were determined using PROC GLIMMIX in SAS.ResultsNo differences were detected for body weight, body condition score, or dry matter intake averaged over the first 21 d postpartum. Cows receiving BCK had significantly lower liver TG concentrations compared to CON (6.60% vs. 4.77%, standard error of the mean (SEM) 0.49) during the first 3 weeks of lactation. Infusion of BCA increased milk yield (39.5 vs. 35.3 kg/d, SEM 1.8), milk fat yield (2.10 vs. 1.69 kg/d, SEM 0.08), and lactose yield (2.11 vs. 1.67 kg/d, SEM 0.07) compared with CON. Compared to CON, cows receiving BCA had lower plasma glucose (55.0 vs. 59.2 mg/dL, SEM 0.86) but higher β-hydroxybutyrate (9.17 vs. 6.00 mg/dL, SEM 0.80).ConclusionsOverall, BCAA supplementation in this study improved milk production, whereas BCKA supplementation reduced TG accumulation in the liver of fresh cows.Graphical

Preanalytical impact on the accuracy of measurements of glucagon, GLP-1 and GIP in clinical trials

Background Plasma concentrations of glucagon, GLP-1 and GIP are reported in numerous clinical trials as outcome measures but preanalytical guidelines are lacking. We addressed the impact of commonly used blood containers in metabolic research on measurements of glucagon, GLP-1 and GIP in humans. Methods Seventeen overweight individuals were subjected to an overnight fast followed by an intravenous infusion of amino acids to stimulate hormonal secretion. Blood was sampled into five containers: EDTA-coated tubes supplemented with DMSO (control), a neprilysin inhibitor, aprotinin (a kallikrein inhibitor) or a DPP-4 inhibitor, and P800 tubes. Plasma was kept on ice before and after centrifugation and stored at −80 Celsius until batch analysis using validated sandwich ELISAs or radioimmunoassays (RIA). Results Measures of fasting plasma glucagon did not depend on sampling containers, whether measured by ELISA or RIA. Amino acid-induced hyperglucagonemia was numerically higher when blood was collected into P800 tubes or tubes with aprotinin. The use of p800 tubes resulted in higher concentrations of GLP-1 by RIA compared to control tubes but not for measurements with sandwich ELISA. Plasma concentrations of GIP measured by ELISA were higher in control tubes and negatively affected by P800 and the addition of aprotinin. Conclusions The choice of blood containers impacts on measurements of plasma concentrations of glucagon, GLP-1 and GIP, and based on this study, we recommend using EDTA-coated tubes without protease inhibitors or P800 tubes for measurements of glucagon, GLP-1 and GIP in clinical trials.

High-protein diet with excess leucine prevents inactivity-induced insulin resistance in women

Background and aimsMuscle inactivity leads to muscle atrophy and insulin resistance. The branched-chain amino acid (BCAA) leucine interacts with the insulin signaling pathway to modulate glucose metabolism. We have tested the ability of a high-protein BCAA-enriched diet to prevent insulin resistance during long-term bed rest (BR). MethodsStable isotopes were infused to determine glucose and protein kinetics in the postabsorptive state and during a hyperinsulinemic-euglycemic clamp in combination with amino acid infusion (Clamp+AA) before and at the end of 60 days of BR in two groups of healthy, young women receiving eucaloric diets containing 1 g of protein/kg per day (n=8) or 1.45 g of protein/kg per day enriched with 0.15 g/kg per day of BCAAs (leucine/valine/isoleucine=2/1/1) (n=8). Body composition was determined by Dual X-ray Absorptiometry. ResultsBR decreased lean body mass by 7.6±0.3% and 7.2±0.8% in the groups receiving conventional or high protein-BCAA diets, respectively. Fat mass was unchanged in both groups.At the end of BR, percent changes of insulin-mediated glucose uptake significantly (p=0.01) decreased in the conventional diet group from 155±23% to 84±10% while did not change significantly in the high protein-BCAA diet group from 126±20% to 141±27% (BR effect, p=0.32; BR/diet interaction, p=0.01; Repeated Measures ANCOVA). In contrast, there were no BR/diet interactions on proteolysis and protein synthesis Clamp+AA changes in the conventional diet and the high protein-BCAA diet groups. ConclusionA high protein-BCAA enriched diet prevented inactivity-induced insulin resistance in healthy women.

Perioperative Intravenous Amino Acid Infusion in Major Urologic Surgery.

Post-operative acute kidney injury (PO-AKI) is a serious complication that may occur after major abdominal surgery. The administration of intravenous perioperative amino acids (AAs) has been proven to increase kidney function and has some beneficial effects to prevent PO-AKI. The aim of this study was to establish if the perioperative infusion of AAs may reduce the incidence of PO-AKI in patients undergoing major urological minimally invasive surgery. From a total of 331 patients, the first 169 received perioperative crystalloid fluids and the following 162 received perioperative AA infusions. PO-AKIs were much higher in the crystalloid group compared to the AA group (34 vs. 17, p = 0.022) due to a lower incidence of KDIGO I and II in the AA group (14 vs. 30 p = 0.016). The AA group patients who developed a PO-AKI presented more risk factors compared to those who did not (2 (2-4) vs. 1 (1-2), p = 0.031) with a cut-off of 3 risk factors in the ROC curve (p = 0.007, sensitivity 47%, specificity 83%). The hospital length of stay was higher in the crystalloid group (p < 0.05) with a consequent saving in hospital costs. Perioperative AA infusion may help reduce the incidence of PO-AKI after major urological minimally invasive surgery.

Amino acid–dependent regulation of insulin-like peptide signaling is mediated by TOR and GATA factors in the disease vector mosquito Aedes aegypti

Aedes aegypti female mosquitoes require vertebrate blood for their egg production and consequently they become vectors of devastating human diseases. Amino acids (AAs) and nutrients originating from a blood meal activate vitellogenesis and fuel embryo development of anautogenous mosquitoes. Insulin-like peptides (ILPs) are indispensable in reproducing female mosquitoes, regulating glycogen and lipid metabolism, and other essential functions. However, how ILPs coordinate their action in response to the AA influx in mosquito reproduction was unknown. We report here that the AA/Target of Rapamycin (TOR) signaling pathway regulates ILPs through GATA transcription factors (TFs). AA infusion combined with RNA-interference TOR silencing of revealed their differential action on ILPs, elevating circulating levels of several ILPs but inhibiting others, in the female mosquito. Experiments involving isoform-specific CRISPR-Cas9 genomic editing and chromatin immunoprecipitation assays showed that the expression of ilp4ilp6, and ilp7 genes was inhibited by the GATA repressor (GATAr) isoform in response to low AA-TOR signaling, while the expression of ilp1ilp2ilp3ilp5, and ilp8 genes was activated by the GATA activator isoform after a blood meal in response to the increased AA-TOR signaling. FoxO, a downstream TF in the insulin pathway, was involved in the TOR-GATAr-mediated repression of ilp4ilp6, and ilp7 genes. This work uncovered how AA/TOR signaling controls the ILP pathway in modulation of metabolic requirements of reproducing female mosquitoes.