[Application of branch-first technique in total thoracic aorta replacement: short and medium term effect of 11 cases]

Objective: To examine the short and medium term effect of branch-first technique in total thoracic aorta replacement. Methods: The clinical data of eleven patients with ascending aortic aneurysms or type A aortic dissection+Crawford Ⅰ or Ⅱ total thoracoabdominal aortic aneurysm who were treated at Department of Cardiovascular Surgery in Henan Province Chest Hospital from January 2018 to July 2021 were retrospectively analyzed. There were 7 males and 4 females, aging (38±5) years (range: 28 to 45 years), 7 cases of whom were diagnosed with Marfan syndrome, 1 case was diagnosed with coarctation of aorta. Operations were performed under mild hypothermic and branch-first technique. Firstly, the middle and small incision in the chest was combined with the 6th intercostal incision in the left posterior lateral side. Secondly, four branches artificial blood vessels were anastomosed with the brachiocephalic artery to ensure the blood supply to the brain. After the circulation was blocked, intracardiac and aortic proximal operations were performed. Intercostal artery reconstruction and thoracic descending aorta replacement were completed after opening circulation. Results: The operative time of this group was (645.9±91.7) minutes (range: 505 to 840 minutes). One case had cerebral infarction and 1 case had chylothorax. The patients were followed up 4 to 47 months, 1 patient underwent thoracic and abdominal aorta+iliac artery resection and replacement due to the progression of abdominal aortic aneurysm 3 months after operation. Intercostal artery obstruction occurred in 2 cases, and the rest lived well. Conclusions: One-stage whole thoracic aorta replacement with branch-first technique has satisfactory results in the short and medium term, with no risk of residual aortic aneurysm rupture. It is an effective treatment for young and organs function well patients with complex aortic lesions.

278 Awardee Talk: Progesterone Regulates the Abundance of Mrnas and Proteins Involved in Polyamine Metabolism in the Sheep Endometrium

Agmatine and polyamines (putrescine, spermidine, and spermine), metabolites of L-arginine, are important for development of mammalian conceptuses. The objective of this study was to determine if exogenous progesterone administered during the pre-implantation period, which accelerates conceptus development, alters the expression of mRNAs and proteins involved in the metabolism of agmatine and polyamines in the sheep uterus during pregnancy. Mature Suffolk ewes were bred to fertile rams and assigned randomly to be treated with daily i.m. injections of either 1ml corn oil (CO;n=28) or 25mg progesterone in corn oil (P4;n=20) from Day 1.5 through Day 8 after breeding (Day 0). Ewes were hysterectomized on Day 9, 12, or 125 of gestation and endometrial samples were collected. The expression of candidate mRNAs was quantified using qPCR and proteins localized using immunohistochemistry. On Day 9 of pregnancy, the expression of mRNAs for AMD1 (P < 0.01), ASL (P < 0.01), and SLC12A8 (P < 0.05) was greater in endometria of P4-treated compared to CO-treated ewes. The expression for MAT2B mRNA was greater (P < 0.001) for P4-treated compared to CO-treated ewes on both Days 9 and 12. On Day 125 of gestation, endometria from P4-treated ewes tended to have greater expression of SAT1 (P < 0.10) mRNA compared to CO-treated ewes. In contrast, the expression of AMD1(P < 0.01), MAT2B (P < 0.05), OAT (P < 0.05), SMOX (P < 0.05), and SLC12A8 (P < 0.05) mRNAs was lower in endometria from P4-treated compared to CO-treated ewes on Day 125. Exogenous P4 appeared to increase the relative abundance of SAT1 and SMOX proteins in the uterine luminal and glandular epithelia on Day 125 of pregnancy. These results suggest that early administration of progesterone may alter the biosynthesis of agmatine and polyamines in the sheep uterus during the pre-implantation period of pregnancy with potential ‘programming’ effects manifested in late pregnancy.

219 Evaluation of Dietary Arginine Supplementation to Increase Placental Nutrient Transporters of Aged Mares

Nine pregnant mares (18.2 ± 0.7 y; 493.82 ± 13 kg BW) were used to test the hypothesis that dietary supplementation of arginine would enhance placental vascularity and nutrient transport throughout gestation in aged mares. Mares were balanced by age, BW, and stallion pairing, and randomly assigned to one of two dietary treatments consisting of supplemental L-arginine (50 mg/kg BW; n=5) or L-alanine (100 mg/kg BW; n=4; isonitrogenous control). Mares were individually fed concentrate top-dressed with the respective amino acid treatment plus ad libitum access to Coastal bermudagrass hay. Treatments began on d 14 of gestation and were terminated at parturition. Mare BW, BCS, and rump fat were determined every 28 d and concentrate adjusted accordingly. Parturition was attended with foaling variables and placental measures recorded. Placental tissue from the pregnant horn underwent histological analyses to assess cell-specific localization of vascular endothelial growth factor (VEGF) and cationic amino acid transporter 1 (CAT1) proteins. Semiquantitative analyses were performed using 10 non-overlapping images per sample fixed in a 10X field (Fiji ImageJ v1.2). Data were analyzed using SAS PROC MIXED procedure. BW increased (P < 0.01) in all mares with advancing gestation. BW, BCS, and gestation length of mares were not influenced (P > 0.05) by supplemental arginine. Compared with arginine-supplemented mares, control mares had a thicker rump fat layer (P < 0.01) at parturition. Body length, height, and BW of foals at birth, as well as placental weight, volume, and positive staining for VEGF and CAT1 at parturition were not affected (P > 0.05) by maternal arginine supplementation. These results indicate dietary arginine supplementation (50 mg/kg BW) is safe for gestating mares and promotes mobilization of white adipose tissue. A larger number of mares is required to determine effects of supplemental arginine on embryonic/fetal survival and growth in mares.

P15.11.A 18F-Fluciclovine PET/CT to distinguish radiation necrosis from tumour progression in brain metastases treated with stereotactic radiosurgery: results of a prospective pilot study

Background

Amino acid PET radiopharmaceutical, 18F-fluciclovine, shows increased uptake in brain tumors relative to normal tissue and may be a useful tool for detecting recurrent brain metastases. Here, we report results from a prospective pilot study evaluating the use of 18F-fluciclovine PET/CT to distinguish radiation necrosis from tumour progression among patients with brain metastases treated with stereotactic radiosurgery (SRS).

Material and Methods

The primary objective was to estimate the accuracy of 18F-fluciclovine PET/CT in distinguishing radiation necrosis from tumour progression. The trial included adults with brain metastases who underwent SRS and presented with a follow up MRI brain (with DSC MR perfusion) which was equivocal for radiation necrosis versus tumour progression. Within 30 days of equivocal MRI brain, patients underwent an 18F-fluciclovine PET/CT (Siemens mCT) acquired 5-15 min post-injection with images generated by PSF reconstruction. Quantitative metrics for each lesion were documented and lesion to normal brain SUVmean ratios were calculated. The reference standard for diagnosis of radiation necrosis vs tumour progression was clinical follow up with MRI brain every 2-4 months until multidisciplinary consensus or tissue confirmation.

Results

Of 16 patients enrolled between 7/2019-11/2020, 1 patient died prior to diagnosis, allowing 15 evaluable subjects with 20 lesions. Primary histology was NSCLC in 9 (45%) lesions, breast in 7 (35%), melanoma in 3 (15%), and endometrial in 1 (5%). The final diagnosis was radiation necrosis in 16 (80%) lesions and tumour progression in 4 (20%). SUVmax was a statistically significant predictor of tumour progression (P = 0.011), with higher SUVmax values indicative of tumour progression. The area under the ROC curve was 0.833 (95% CI: 0.590, 1.0). A cutoff of 4.3 provided a sensitivity to identify tumour progression of 1.0 (4/4) and specificity to rule out tumour progression of 0.63 (10/16). SUVmean (P = 0.018), SUVpeak (P = 0.007), and SUVpeak/normal (P = 0.002) also reached statistical significance as predictors of tumour progression, with higher SUVmax values indicative of tumour progression. SUVmax/normal (P = 0.1) and SUVmean/normal (P = 0.5) were not statistically significant. The AUC for SUVmax was not significantly higher than the AUCs for the other quantitative variables (P-values > 0.2).

Conclusion

In this prospective pilot study, 18F Fluciclovine PET/CT demonstrated promising accuracy to distinguish radiation necrosis from tumour progression among patients with brain metastases previously treated with SRS. Using SUVmax, a cutpoint of 4.3 provided a sensitivity of 1.0 and specificity of 0.63. Confirmatory phase II and III studies are ongoing.

Creatine metabolism at the uterine-conceptus interface during early gestation in sheep†

Ruminant conceptuses that elongate and attach to the uterine luminal epithelium (LE) to establish pregnancy require a large amount of ATP. The creatine (Cr)-creatine kinase (CK)-phosphocreatine (PCr) system re-generates ATP in dividing and migrating cells such as the conceptus trophectoderm cells. However, little is known about metabolism of Cr within uterine and conceptus tissues in livestock species during early gestation. In this study, Suffolk ewes were ovariohysterectomized on Day 9, 12, 15, 16, 17, 18, 20 or 21 of pregnancy (n = 2-5 animals/per day) to investigate metabolites, mRNAs, and proteins of the Cr-CK-PCr system at uterine-conceptus interface. Amounts of Cr and guanidinoacetate (GA) in uterine flushings increased between Days 12 and 17 of pregnancy. Endometrial expression of mRNAs for GA formation (AGAT), Cr synthesis (GAMT), and Cr/PCr utilization (CKB) was greater on Days 17 and 21 than on Days 9 and 12 of pregnancy. Immunoreactive AGAT was detected in uteri only on Day 21 but not in uteri or conceptuses at earlier days of pregnancy. GAMT, SLC6A8, and CKs were expressed in uterine luminal and glandular epithelia. Immunoreactive CKs (CKB, CKM and CKMT1) appeared greater on Day 9 than Day 17 of pregnancy. Immunoreactive GAMT and CKs appeared greater in trophectoderm of conceptuses on Day 20 than on Day 15 of pregnancy whereas the opposite was observed for that of SLC6A8. This study provides insights into cell-, tissue-, and time-specific metabolism of Cr at the uterine-conceptus interface suggesting a role for the Cr-CK-PCr system in ovine conceptus development and implantation.

Dietary L-arginine supplementation increases the hepatic expression of AMP-activated protein kinase in rats

The goal of this study was to elucidate the molecular mechanisms responsible for the anti-obesity effect of L-arginine supplementation in diet-induced obese rats. Male Sprague-Dawley rats were fed either a low-fat or high-fat diet for 15 weeks. Thereafter, lean or obese rats were pair-fed their same respective diets and received drinking water containing either 1.51% L-arginine-HCl or 2.55% L-alanine (isonitrogenous control) for 12 weeks. Gene and protein expression of key enzymes in the metabolism of energy substrates were determined using real-time polymerase-chain reaction and western blotting techniques. The mRNA levels of hepatic fatty acid synthase and stearoyl-CoA desaturase were reduced (P < 0.05) but those of hepatic AMP-activated protein kinase-α (AMPKα), peroxisome proliferator activator receptor γ coactivator-1α, and carnitine palmitoyltransferase I (CPT-I), as well as skeletal muscle CPT-I were increased (P < 0.05) by L-arginine treatment. The protein expression and activity of hepatic AMPKα markedly increased (P < 0.05) but the activity of hepatic acetyl-CoA carboxylase (ACC) decreased (P < 0.05) in response to dietary L-arginine supplementation. Collectively, our results indicate that liver is the major target for the action of dietary L-arginine supplementation on reducing white-fat mass in diet-induced obese rats by inhibiting fatty acid synthesis and increasing fatty acid oxidation via the AMPK-ACC signaling pathway. Additionally, increased CPT-I expression in skeletal muscle may also contribute to the enhanced oxidation of long-chain fatty acids in L-arginine-supplemented rats.

Inhibition of SHMT2 mRNA translation increases embryonic mortality in sheep

The one-carbon metabolism (OCM) pathway provides purines and thymidine for synthesis of nucleic acids required for cell division, and S-adenosyl methionine for polyamine and creatine syntheses and the epigenetic regulation of gene expression. This study aimed to determine if serine hydroxymethyltransferase 2 (SHMT2), a key enzyme in the OCM pathway, is critical for ovine trophectoderm (oTr) cell function and conceptus development by inhibiting translation of SHMT2 mRNA using a morpholino antisense oligonucleotide (MAO). In vitro treatment of oTr cells with MAO-SHMT2 decreased expression of SHMT2 protein, which was accompanied by reduced proliferation (P = 0.053) and migration (P &lt; 0.05) of those cells. Intrauterine injection of MAO-SHMT2 in ewes on Day 11 post-breeding tended to decrease the overall pregnancy rate (on Days 16 and 18) compared to MAO-control (3/10 vs 7/10, P = 0.07). The three viable conceptuses (n = 2 on Day 16 and n = 1 on Day 18) recovered from MAO-SHMT2 ewes had only partial inhibition of SHMT2 mRNA translation. Conceptuses from the three pregnant MAO-SHMT2 ewes had similar levels of expression of mRNAs and proteins involved in OCM as compared to conceptuses from MAO-control ewes. These results indicate that knockdown of SHMT2 protein reduces proliferation and migration of oTr cells (in vitro) to decrease elongation of blastocysts from spherical to elongated forms. These in vitro effects suggest that increased embryonic deaths in ewes treated with MAO-SHMT2 are the result of decreased SHMT2-mediated trophectoderm cell proliferation and migration supporting a role for the OCM pathway in survival and development of ovine conceptuses.

3D-Stacked Multistage Inertial Microfluidic Chip for High-Throughput Enrichment of Circulating Tumor Cells

Whether for cancer diagnosis or single-cell analysis, it remains a major challenge to isolate the target sample cells from a large background cell for high-efficiency downstream detection and analysis in an integrated chip. Therefore, in this paper, we propose a 3D-stacked multistage inertial microfluidic sorting chip for high-throughput enrichment of circulating tumor cells (CTCs) and convenient downstream analysis. In this chip, the first stage is a spiral channel with a trapezoidal cross-section, which has better separation performance than a spiral channel with a rectangular cross-section. The second and third stages adopt symmetrical square serpentine channels with different rectangular cross-section widths for further separation and enrichment of sample cells reducing the outlet flow rate for easier downstream detection and analysis. The multistage channel can separate 5 μm and 15 μm particles with a separation efficiency of 92.37% and purity of 98.10% at a high inlet flow rate of 1.3 mL/min. Meanwhile, it can separate tumor cells (SW480, A549, and Caki-1) from massive red blood cells (RBCs) with a separation efficiency of >80%, separation purity of >90%, and a concentration fold of ~20. The proposed work is aimed at providing a high-throughput sample processing system that can be easily integrated with flowing sample detection methods for rapid CTC analysis.

Ovine conceptus homogenates metabolize fructose for metabolic support during the peri-implantation period of pregnancy

Roles of fructose in elongating ovine conceptuses are poorly understood, despite it being the major hexose sugar in fetal fluids and plasma throughout gestation. Therefore, we determined if elongating ovine conceptuses utilize fructose via metabolic pathways for survival and development. Immunohistochemical analyses revealed that trophectoderm and extra-embryonic endoderm express ketohexokinase and aldolase B during the peri-implantation period of pregnancy for conversion of fructose into fructose-1-phosphate for entry into glycolysis and related metabolic pathways. Conceptus homogenates were cultured with 14C-labeled glucose and/or fructose under oxygenated and hypoxic conditions to assess contributions of glucose and fructose to the pentose cycle (PC), tricarboxylic acid cycle, glycoproteins, and lipid synthesis. Results indicated that both glucose and fructose contributed carbons to each of these pathways, except for lipid synthesis, and metabolized to pyruvate and lactate, with lactate being the primary product of glycolysis under oxygenated and hypoxic conditions. We also found that: 1) conceptuses preferentially oxidized glucose over fructose (P < 0.05); 2) incorporation of fructose and glucose at 4 mM each into the PC by Day 17 conceptus homogenates was similar in the presence or absence of glucose, but incorporation of glucose into the PC was enhanced by the presence of fructose (P < 0.05); 3) incorporation of fructose into the PC in the absence of glucose was greater under oxygenated conditions (P < 0.01); and 4) incorporation of glucose into the PC under oxygenated conditions was greater in the presence of fructose (P = 0.05). These results indicate that fructose is an important metabolic substrate for ovine conceptuses.

Dietary supplementation with branched-chain amino acids enhances milk production by lactating sows and the growth of suckling piglets

Background

Under current dietary regimens, milk production by lactating sows is insufficient to sustain the maximal growth of their piglets. As precursors of glutamate and glutamine as well as substrates and activators of protein synthesis, branched-chain amino acids (BCAAs) have great potential for enhancing milk production by sows.

Methods

Thirty multiparous sows were assigned randomly into one of three groups: control (a corn- and soybean meal-based diet), the basal diet + 1.535% BCAAs; and the basal diet + 3.07% BCAAs. The ratio (g/g) among the supplemental L-isoleucine, L-leucine and L-valine was 1.00:2.56:1.23. Diets were made isonitrogenous by the addition of appropriate amounts of L-alanine. Lactating sows had free access to drinking water and their respective diets. The number of live-born piglets was standardized to 9 per sow at d 0 of lactation (the day of parturition). On d 3, 15 and 29 of lactation, body weights and milk consumption of piglets were measured, and blood samples were obtained from sows and piglets 2 h and 1 h after feeding and nursing, respectively.

Results

Feed intake did not differ among the three groups of sows. Concentrations of asparagine, glutamate, glutamine, citrulline, arginine, proline,  BCAAs, and many other amino acids  were greater (P < 0.05) in the plasma of BCAA-supplemented sows and their piglets than those in the control group. Compared with the control, dietary supplementation with 1.535% and 3.07% BCAAs increased (P < 0.05) concentrations of free and protein-bound BCAAs, glutamate plus glutamine, aspartate plus asparagine, and many other amino acids in milk; milk production by 14% and 21%, respectively; daily weight gains of piglets by 19% and 28%, respectively, while reducing preweaning mortality rates by 50% and 70%, respectively.

Conclusion

Dietary supplementation with up to 3.07% BCAAs enhanced milk production by lactating sows, and the growth and survival of their piglets.

Elongating porcine conceptuses can utilize Glutaminolysis as an Anaplerotic pathway to maintain the TCA cycle

During the peri-implantation period of pregnancy, the trophectoderm of pig conceptuses utilize glucose via multiple biosynthetic pathways to support elongation and implantation, resulting in limited availability of pyruvate for metabolism via the TCA cycle. Therefore, we hypothesized that porcine trophectoderm cells replenish TCA cycle intermediates via a process known as anaplerosis, and that trophectoderm cells convert glutamine to α-ketoglutarate, a TCA cycle intermediate, through glutaminolysis. Results demonstrate: 1) that expression of glutaminase (GLS) increases in trophectoderm and glutamine synthetase (GLUL) increases in extra-embryonic endoderm of conceptuses, suggesting that extra-embryonic endoderm synthesizes glutamine, and trophectoderm converts glutamine into glutamate; and 2) that expression of glutamate dehydrogenase 1 (GLUD1) decreases and expression of aminotransferases including PSAT1 increase in trophectoderm, suggesting that glutaminolysis occurs in the trophectoderm through the GLS-aminotransferase pathway during the peri-implantation period. We then incubated porcine conceptuses with 13C-glutamine in the presence or absence of glucose in the culture media, and then monitored the movement of glutamine-derived carbons through metabolic intermediates within glutaminolysis and the TCA cycle. The accumulation of 13C-labeled carbons significantly increased in glutamate, α-ketoglutarate, succinate, malate, citrate, and aspartate in the absence of glucose in the media. Collectively, our results indicate that during the peri-implantation period of pregnancy, the proliferating and migrating trophectoderm cells of elongating porcine conceptuses utilize glutamine via glutaminolysis as an alternate carbon source to maintain TCA cycle flux.

Impact of probiotic Limosilactobacillus reuteri DSM 17938 on amino acid metabolism in the healthy newborn mouse

We studied the effect of feeding a single probiotic Limosilactobacillus reuteri DSM 17938 (LR 17938) on the luminal and plasma levels of amino acids and their derivatives in the suckling newborn mouse, using gas chromatography and high-performance liquid chromatography. We found that LR 17938 increased the relative abundance of many amino acids and their derivatives in stool, while it simultaneously significantly reduced the plasma levels of three amino acids (serine, citrulline, and taurine). Many peptides and dipeptides were increased in stool and plasma, notably gamma-glutamyl derivatives of amino acids, following ingestion of the LR 17938. Gamma-glutamyl transformation of amino acids facilitates their absorption. LR 17938 significantly upregulated N-acetylated amino acids, the levels of which could be useful biomarkers in plasma and warrant further investigation. Specific fecal microbiota were associated with higher levels of fecal amino acids and their derivatives. Changes in luminal and circulating levels of amino acid derivatives, polyamines, and tryptophan metabolites may be mechanistically related to probiotic efficacy.

The "ideal protein" concept is not ideal in animal nutrition

Amino acids (AAs) are required for syntheses of proteins and low-molecular-weight substances with enormous physiological importance. Since 1912, AAs have been classified as nutritionally essential amino acids (EAAs) or nonessential amino acids (NEAAs) for animals. EAAs are those AAs that are either not synthesized or insufficiently synthesized de novo in the organisms. It was assumed that all NEAAs (now known as AAs that are synthesizable in animal cells de novo [AASAs]) were formed sufficiently in animals and were not needed in diets. However, studies over the past three decades have shown that sufficient dietary AASAs (e.g. glutamine, glutamate, glycine, and proline) are necessary for the maximum growth and optimum health of pigs, chickens, and fish. Thus, the concept of "ideal protein" (protein with an optimal EAA pattern that precisely meets the physiological needs of animals), which was originally proposed in the 1950s but ignored AASAs, is not ideal in animal nutrition. Ideal diets must provide all physiologically and nutritionally essential AAs. Improved patterns of AAs in diets for swine and chickens as well as zoo and companion animals have been proposed in recent years. Animal-sourced feedstuffs supply abundant EAAs and AASAs (including glutamate, glutamine, glycine, proline, 4-hydroxyproline, and taurine) for diets of swine, poultry, fish, and crustaceans to improve their growth, development, reproduction, and health, while sustaining global animal production. Nutritionists should move beyond the "ideal protein" concept to consider optimum ratios and amounts of all proteinogenic AAs in diets for mammals, birds, and aquatic animals, and, in the case of carnivores, also taurine.

Equine enterocytes actively oxidize l-glutamine, but do not synthesize l-citrulline or l-arginine from l-glutamine or l-proline in vitro

In livestock species, the enterocytes of the small intestine are responsible for the synthesis of citrulline and arginine from glutamine and proline. At present, little is known about de novo synthesis of citrulline and arginine in horses. To test the hypothesis that horses of different age groups can utilize glutamine and proline for the de novo synthesis of citrulline and arginine, jejunal enterocytes from 19 horses of three different age groups: neonates (n = 4; 7.54 ± 2.36 d of age), adults (n = 9; 6.4 ± 0.35 yr), and aged (n = 6; 22.9 ± 1.0 yr) with healthy gastrointestinal tracts were used in the present study. Enterocytes were isolated from the jejunum and incubated at 37 °C for 30 min in oxygenated (95% O2/5% CO2) Krebs bicarbonate buffer (pH 7.4) containing 5 mM D-glucose and 0 mM, 2-mM L-[U-14C]glutamine, or 2 mM L-[U-14C]proline plus 2 mM L-glutamine. Concentrations of arginine, citrulline, and ornithine in cells plus medium were determined using high-performance liquid chromatography. Results indicate that the rate of oxidation of glutamine to CO2 was high in enterocytes from neonatal horses, but low in cells from adult and aged horses. Enterocytes from all age groups of horses did not degrade proline into CO2. Regardless of age, equine enterocytes formed ornithine from glutamine and proline, but failed to convert ornithine into citrulline and arginine. Because arginine is an essential substrate for the synthesis of not only proteins, but also nitrogenous metabolites (e.g., nitric oxide, polyamines, and creatine), our novel findings have important implications for the nutrition, performance, and health of horses.