Glutamate Dehydrogenase Activity Research Articles

Drought, Salinity, and Low Nitrogen Differentially Affect the Growth and Nitrogen Metabolism of Sophora japonica (L.) in a Semi-Hydroponic Phenotyping Platform.

Abiotic stresses, such as salinity, drought, and nutrient deficiency adversely affect nitrogen (N) uptake and assimilation in plants. However, the regulation of N metabolism and N pathway genes in Sophora japonica under abiotic stresses is unclear. Sophora japonica seedlings were subjected to drought (5% polyethylene glycol 6,000), salinity (75mM NaCl), or low N (0.01mM NH4NO3) for 3weeks in a semi-hydroponic phenotyping platform. Salinity and low N negatively affected plant growth, while drought promoted root growth and inhibited aboveground growth. The NH4+/NO3− ratio increased under all three treatments with the exception of a reduction in leaves under salinity. Drought significantly increased leaf NO2− concentrations. Nitrate reductase (NR) activity was unaltered or increased under stresses with the exception of a reduction in leaves under salinity. Drought enhanced ammonium assimilation with increased glutamate synthase (GOGAT) activity, although glutamine synthetase (GS) activity remained unchanged, whereas salinity and low N inhibited ammonium assimilation with decreased GS activity under salt stress and decreased GOGAT activity under low N treatment. Glutamate dehydrogenase (GDH) activity also changed dramatically under different stresses. Additionally, expression changes of genes involved in N reduction and assimilation were generally consistent with related enzyme activities. In roots, ammonium transporters, especially SjAMT1.1 and SjAMT2.1a, showed higher transcription under all three stresses; however, most nitrate transporters (NRTs) were upregulated under salinity but unchanged under drought. SjNRT2.4, SjNRT2.5, and SjNRT3.1 were highly induced by low N. These results indicate that N uptake and metabolism processes respond differently to drought, salinity, and low N conditions in S. japonica seedlings, possibly playing key roles in plant resistance to environmental stress.

Interplay of hydrogen peroxide and nitric oxide: systemic regulation of photosynthetic performance and nitrogen metabolism in cadmium challenged cyanobacteria.

In the present study, thepotential role of hydrogen peroxide (H2O2) and nitric oxide (NO) has been well recorded in the induction of cadmium (Cd) stress tolerance in cyanobacteria. In this regard, H2O2 and SNP (sodium nitroprusside, NO donor), were applied to Nostoc muscorum and Anabaena sp. exposed to Cd (6µM) stress, to analyze different physiological and biochemical parameters. Results revealed that treatment of Cd reduced the growth, pigment contents, photosynthetic oxygen yield and performance of PS II photochemistry (decreased chlorophyll a fluorescence parameters, i.e., ФPo, Ψo, ФEo, PIABS along with Fv/Fo and increased the energy fluxparameters, i.e., ABS/RC, TRo/RC, ETo/RC, DIo/RC along with Fo/Fv. Similarly, uptake of nitrate (NO3 -) and nitrite (NO2 -), as well as the activities of nitrate and ammonia assimilating enzymes along with carbohydrate content, were severely affected by Cd toxicity and notwithstanding this, glutamate dehydrogenase (GDH) activity exhibited reverse trend. Exogenous application of a very low dose (1µM) of H2O2 (only for 3h) and NO (SNP; 10µM) notably counteracted Cd-induced toxicity. Nevertheless, the positive impact of H2O2 got reversed under the treatment of PTIO (NO scavenger) and LNAME (inhibitor of nitric oxide synthase; NOS) while NO could work efficiently even in the presence of NAC (H2O2 scavenger) and DPI (inhibitor of NADPH oxidase); hence indicated towards the H2O2 mediated NO signaling in averting Cd induced toxicity in test cyanobacteria. In conclusion, current finding demonstrated a positive cross-talk between H2O2 and NO for providing tolerance to cyanobacteria against Cd stress.

Matrix and Sampling Effects on Quantification of Protein Biomarkers of Drug-Induced Liver Injury.

Macrophage colony stimulating factor 1 receptor (MCSF1R), osteopontin (OPN), high-mobility group protein B1 (HMGB1), glutamate dehydrogenase (GLDH), keratin 18 (K18), and caspase-cleaved keratin 18 (ccK18) are considered promising mechanistic biomarkers for the diagnosis of drug-induced liver injury. Here, we aim to elucidate the impact of the sample matrix and handling on the quantification of these emerging protein biomarkers. We investigated effects such as time from collection to centrifugation during serum (± gel) or EDTA plasma preparation on two assay platforms: immunoaffinity liquid chromatography mass spectrometric assays and sandwich immunoassays. Furthermore, we measured GLDH activity with an enzymatic activity assay. Matrix effects were observed particularly for HMGB1 and MCSF1R. HMGB1 levels were higher in serum than in plasma, whereas higher concentrations of MCSF1R were observed in plasma than in serum. A comparison of sample collection to centrifugation time ranging from 15 to 60 min demonstrated increasing levels of HMGB1 in serum, while MCSF1R, OPN, GLDH, and ccK18 concentrations remained stable. Additionally, there was a poor correlation in HMGB1 and ccK18 levels between serum and plasma. Considering the observed matrix effects, we recommend plasma as a matrix of choice and cross-study comparison studies to be limited to those using the same matrix.

Cr (VI)-induced oxidative damage impairs ammonia assimilation into organic forms in Solanum lycopersicum L.

Chromium (Cr) is a dangerous metal that has been found in the environment in high amounts as the result of numerous human activities, with proven negative effects on various organisms, including plants. The exposure of some plant species to this metal resulted in reduced growth, impaired nutrient uptake, and led to an overproduction of reactive oxygen species (ROS), ultimately causing oxidative damage. Nevertheless, studies regarding the impact of Cr on nitrogen (N) metabolism, the main limiting factor for plant growth, either directly or through the occurrence of oxidative stress, are scarce. Thus, this work aimed to explore the interplay between ammonia (NH4+) assimilation, redox homeostasis and antioxidant (AOX) system of tomato plants exposed to increased concentrations of Cr (VI) (0, 5 and 10 µM). The results revealed that Cr (VI) induced biometric damages, with roots being the most affected organ. Glutamine synthetase (GS) was differentially influenced by the metal at the gene expression, protein and activity levels, whereas glutamate dehydrogenase (GDH) activity was enhanced. Moreover, in Cr (VI)-treated plants, the observed oxidative damage was dependent on metal concentration and plant organ, with a differential accumulation of ROS and a generalized increase of lipid peroxidation (LP) recorded, being paired with an overall failure of the enzymatic antioxidant (AOX) system. Still, the non-enzymatic AOX component had a relevant role in the protection of plants against Cr (VI). Overall, the obtained results suggest that Cr (VI)-mediated plant growth reduction resulted from the occurrence of oxidative stress, coupled with the lack of enzymatic AOX defense, which, consequently, affected the NH4+ assimilatory route.

A potential role of Sirtuin3 and its target enzyme activities in patients with ovarian endometrioma

Objective Sirtuin3 (SIRT3) is a NAD+-dependent major mitochondrial deacetylase. In this study, we aimed to investigate SIRT3 levels and their target enzyme activities, including glutamate dehydrogenase (GDH), succinate dehydrogenase (SDH), and manganese superoxide dismutase (MnSOD), also to determine the antioxidant capacity and oxidative stress in tissue, mitochondria and serum samples in ovarian endometrioma patients. Methods We collected serum and endometrioma tissue samples from 30 patients. In the control group, we collected serum and eutopic endometrial tissue samples from 26 women without endometriosis. Results SIRT3 levels were significantly decreased in endometrioma tissue samples compared to the control group. There was no statistically significant difference in SIRT3 levels between patient and control serum samples. Furthermore, there was a decrease in GDH and SDH enzyme activities in both endometrioma tissue homogenate and mitochondria. MnSOD activity was decreased in tissue homogenate but increased in mitochondria and there was no difference in serum. While total SOD activity was decreased, CuZnSOD activity was increased in both tissue and serum samples. Besides these, total antioxidant capacity and advanced oxidation protein products (AOPP) levels were decreased in endometrioma tissue and mitochondria, but there was no difference in serum. Conclusions Our results suggested that decreased levels of SIRT3 in endometrioma may be an important factor in the weakening of mitochondrial energy metabolism and antioxidant defense in endometriosis. We think that SIRT3 deficiency may be an important factor underlying the pathogenesis of endometriosis. More detailed studies are needed to reveal the relationship between SIRT3 and metabolism and oxidative stress in ovarian endometrioma.

Coordination of nitrogen uptake and assimilation favours the growth and competitiveness of moso bamboo over native tree species in high-NH4+ environments

Phenotypic plasticity and competitive strength are major mechanisms determining the success of invasive species and are influenced by abiotic factors. A rise in the ratio of ammonium (NH4+) to nitrate (NO3−) in soils is frequently associated with the invasion of bamboo into broad-leaved evergreen forests. However, the influence of soil nitrogen (N) chemistry on plant growth and interspecific competition in the context of invasion remains insufficiently studied. In the present work, differences in plasticity and interspecific competition between native tree species in broad-leaved evergreen forests and invasive bamboo in response to different N forms were investigated using seedlings grown in a controlled environment. We show that moso bamboo responded positively and strongly to increased soil NH4+/NO3− ratios, while the native tree species Sapium sebiferum, Camellia oleifera, and Machilus pauhoi responded negatively and exhibited limited plasticity. Native tree species growth was significantly inhibited in the presence of moso bamboo under high-NH4+ conditions, whereas native tree species were less affected by interspecific competition when NO3− was supplied as the sole N source. By contrast, moso bamboo growth was significantly inhibited, followed by seedling death, in both monoculture and in mixed culture with prolonged NO3− treatment. All species tested exhibited significantly higher rates of 15NH4+ than 15NO3− uptake, but the Michaelis constant (Km) for 15NH4+ uptake was lower in moso bamboo, indicating higher substrate affinity. Nitrate reductase (NR) and nitrite reductase (NiR) activities showed no inducible effects in moso bamboo compared to the induction response seen in the native tree species in response to NO3−. Activities of glutamine synthetase (GS), glutamate synthase (GOGAT), and glutamate dehydrogenase (GDH) significantly increased with NH4+ provision in roots of moso bamboo, contrasted by a less plastic response in the native tree species. Enhanced ammonification and reduced nitrification in soils is typically observed during bamboo invasion and appears to create a positive soil-plant feedback loop that, due to highly flexible and opportunistic NH4+-acquisition pathways, favours bamboo fitness and invasion into native forests when NH4+ is the dominant N form.

Systemic implications of metallic foreign body syndrome in dairy cattle

This study aimed to evaluate the systemic implications of 37 cattle with traumatic reticulitis, evaluating clinical, laboratory, ultrasonographic and necroscopic changes. A clinical, laboratory and ultrasonographic examination was performed, and the animals were distributed in reticuloperitonitis (GI; n=21) and reticulopericarditis (GII; n=16) traumatic, based on necropsy findings. Blood samples were taken for haematological tests, serum total protein, albumin, globulin, gamma glutamyltransferase (GGT), aspartate aminotransferase (AST), glutamate dehydrogenase (GLDH), creatinine, urea, cortisol, creatine kinase (CK), creatine kinase-MB (CK-MB), cardiac troponin-I (cTn-I), plasma glucose and L-lactate. The abdominocentesis was productive in eight GI (n=8) and seven GII (n=7) animals, allowing the evaluation of physical, cytological and biochemical characteristics of the peritoneal fluid as a total protein, albumin, GLDH, AST, GGT, glucose and L-lactate. Changes in behavior, appetite, dehydration and temperature were observed, most expressive in GII. Hematology showed neutrophilic leukocytosis with regenerative left shift and hyperfibrinogenemia in both groups. Increased globulin, L-lactate concentration and serum GGT, GLDH, CK and CK-MB activity were observed, as well as significant elevation of cTnI (p=0.0190) in GII. In the peritoneal fluid exudate was observed in both groups and a higher concentration of L-lactate in relation to plasma. Ultrasound revealed retocular, cardiac, hepatic and splenic abnormalities. The anatomopathological lesions confirmed the ultrasound findings of both groups. The understanding of the syndrome helps in the diagnosis, as well as the adoption of preventive measures, minimizing the economic impact caused to the dairy cattle breeding.

Enzymatic and fecundity evaluation of Fasciola hepatica exposed to different doses of γ- irradiation in Ethiopian sheep

The upshot of γ-irradiated Fasciola hepatica infection on the activity of plasma glutamate dehydrogenase (GLDH) and γ-glutamyl transpeptidase (GGT) was evaluated in 36 sheep infected with a single dose of 30, 60, 120, and 240 grays and those kept as negative and positive control over 17 weeks. During this period, serum and faecal samples, as well as body weight gains, were taken at weekly intervals. Furthermore, the effects of the irradiation dose (500) for oral vaccination and on the recovery of adult flukes were assessed following primary infection. Eggs were first detected in the faeces of infected sheep on week 8 post-infection. The parasite viability was severely affected by doses of γ-irradiation of 120 Gy or 240 Gy. In the aforementioned doses, relatively low numbers of mature flukes of about 60 (17.1%) and 38 (10.8%) were recovered than the control group, respectively. The sensitized lambs also showed less hepatic damage compared with the controls as indicated by lower levels of the serum enzyme glutamate dehydrogenase and γ- glutamyl transferase significant body weight loss was observed between weeks 6 and 8 post-infection followed by a steady increase of the mean weight of infected animals across time. In conclusion, vaccination of sheep with γ irradiated metacercariae of F. hepatica appeared to affect the number and development of the fluke population resulting in reduced hepatic damage during migration, reduced fecundity after patency, as measured by worm and egg counts, levels of serum glutamate dehydrogenase and γ- glutamyl transferase.

L‐glutamate inhibits blue mould caused by Penicillium expansum in apple fruits by altering the primary nitrogen and carbon metabolisms

SummaryAlthough several studies have shown the ability of l‐glutamate (glutamate) to mitigate the stress imposed by pathogens, the underlying mechanism is still in its infancy. To gain further knowledge, this study focussed on the effect of glutamate on primary nitrogen and carbon metabolisms during apple‐Penicillium expansum interaction. The obtained result showed that glutamate could effectively restrict blue mould rot development in apples, but had no direct impact on fungal growth in vitro. The application of glutamate increased the level of nitrogen in apples, resulting in a disrupted balance of carbon and nitrogen. Consistently, the key enzymes glutamine synthetase (GS) and glutamate synthase (GOGAT) involved in the GS/GOGAT cycle, and the deaminating activity of glutamate dehydrogenase (GDH), forming 2‐oxoglutarate and ammonium from glutamate, were promptly stimulated by glutamate. Interestingly, glutamate led to considerable consumption of the tricarboxylic acid (TCA) cycle intermediates, such as isocitric acid and citric acid, accompanied by the enhancement of malate dehydrogenase and succinate dehydrogenase activities. Collectively, exogenous application of glutamate might confer blue mould resistance in apples, at least in part, by redirecting host’s primary nitrogen and carbon metabolisms, such as the activation of the GS/GOGAT cycle, deaminating activity of GDH and the TCA cycle.

The Plant Growth-Promoting Fungus MF23 (Mycena sp.) Increases Production of Dendrobium officinale (Orchidaceae) by Affecting Nitrogen Uptake and Assimilation.

Dendrobium officinale Kimura et Migo is a traditional and scarce medicinal orchid in China. Mycorrhizal fungi could supply nitrogen (N) to orchids for seed germination and seedling recruitment. However, the N transport mechanism between orchids and the fungus is poorly understand. Early studies found that the fungus MF23 (Mycena sp.) could promote the growth of D. officinale. To better dissect the molecular interactions involved in N transport between D. officinale and MF23, transcriptome and metabolome analyses were conducted on conventional and mycorrhizal cultivations of D. officinale. Moreover, validation tests were carried out in the greenhouse to measure net fluxes of and of roots by a non-invasive micro-test technology (NMT), determine N assimilation enzyme activity by the ELISA, and analyze the expression level of differentially expressed genes (DEGs) of N transporters and DEGs involved in N metabolism by RT-qPCR. Combined transcriptome and metabolome analyses showed that MF23 may influence N metabolism in D. officinale. The expression of DoNAR2.1 (nitrate transporter-activating protein), DoAMT11 (ammonium transporter), DoATFs (amino acid transporters), DoOPTs (oligopeptide transporters), and DoGDHs (glutamate dehydrogenases) in symbiotic D. officinale was upregulated. NMT results showed a preference for in D. officinale and indicated that MF23 could promote the uptake of and, especially for . ELISA results showed that MF23 could increase the activity of glutamine synthetase (GS) and glutamate dehydrogenase. This study suggested that MF23 increases the production of D. officinale by affecting N uptake and assimilation capacity.

Associations between the metabolic status of the cow and colostrum quality as determined by Brix refractometry

Supplying newborn calves with immunoglobins is critical for their health and a daily challenge in the dairy industry. Among various factors determining colostrum quality, the prepartum metabolic status of the cow might be of particular importance. The objective of this observational cross-sectional study was to evaluate relationships between cow-level variables and the colostrum quality as determined by Brix refractometry. A total of 873 cows of varying breed and parity from 124 German dairy herds were included in the study, and blood and urine samples were taken 3 to 1 wk before the expected calving date. Effectively, samples were collected on average 8.2 d (geometric mean) before calving, ranging from 2 to 45 d. The final variable set included body condition score, lameness score, breed, parity, vaccination of the cow, the activity of glutamate dehydrogenase and aspartate aminotransferase, the urine concentration of creatinine, net acid-base excretion, the serum concentration of cholesterol and calcium, and the difference in albumin and total protein concentration. Generalized linear mixed effects regression models with hierarchically structured random effects (cow within herd) using the maximum likelihood method were fitted to the data to identify associations between the Brix value as an outcome and cow-level variables as predictors. Cows entering second parity had lower Brix values compared with cows entering third or greater parity, and prepartum vaccination of cows led to higher Brix values compared with nonvaccinated cows. Cows with a moderate to high lameness score had lower Brix values than cows with low-grade lameness. An increase of glutamate dehydrogenase serum activity and serum calcium concentration were associated with lower Brix values, whereas an increase in the difference of total protein and albumin serum concentration led to higher Brix values. In conclusion, the metabolic health of the cow affects colostrum quality and may cause failure of passive immunoglobulin transfer as well as impaired calf health.

Clinical and pathologic features of acute bovine liver disease in Australia.

Acute bovine liver disease (ABLD) is a sporadic hepatic disease affecting cattle in southern Australia, characterized histologically by striking periportal hepatocellular necrosis. The cause of ABLD is unknown; however, the seasonality and acute presentation of outbreaks suggest mycotoxin involvement. We describe here the clinical and pathologic findings of ABLD in 45 naturally affected cattle from 13 outbreaks occurring from 2010 to 2019 in Victoria, Australia. Outbreaks occurred in herds located along the southern coastal plain of Victoria and were observed most frequently in lactating dairy cattle. Clinical signs commonly included a combination of mild photosensitization, progressive neurologic signs, and hypogalactia, which preceded death by ≤ 48 h. All affected animals had marked elevations in activities of glutamate dehydrogenase, aspartate aminotransferase, and gamma-glutamyl transferase. At autopsy, the most common lesions were serosal petechiae and/or gastrointestinal hemorrhage, and hepatomegaly with a pronounced hepatic reticular pattern. The principal histologic lesion was widespread-severe periportal hepatocellular coagulative necrosis and erythrocyte pooling-which often extended to massive necrosis. Lesions in other organs were uncommon. Our study of ABLD suggests involvement of a potent hepatotoxin that is either directly cytopathic or requires bioactivation by periportal-specific enzymes.

Metabolic and endocrine responses to short-term nutrient imbalances in the feed ration of mid-lactation dairy cows

Short-term imbalances of dietary nutrients occur during natural fluctuations in roughage quality (e.g. on pasture) or temporal shortages of supplementary feed components. In contrast to a deficiency, macronutrients (i.e. carbohydrates, proteins, lipids) beyond the adequate supply with other nutrients may, for instance, alter milk composition, increase BW or result in a greater excretion of nitrogen. Especially dairy cows with a moderate performance, in mid- or late lactation, or in extensive farming systems may be exposed to imbalanced rations. A better understanding of metabolic and endocrine responses depending on macronutrient supply may help to precisely feed dairy cows. The present study investigated short-term metabolic and endocrine responses to different levels of concentrates formulated to particularly provide one major macronutrient source (carbohydrates, proteins or lipids). Based on parity number, lactational stage, milk yield and BW, nine mid-lactating cows (211 ± 19 days in milk) were grouped into three blocks of three animals each. Concentrates (aminogenic: rich in CP and nitrogen sources; glucogenic: high content of carbohydrates and glucogenic precursors; lipogenic: high lipid content) were fed in addition to hay in a factorial arrangement at increasing levels from 2.5 to 7.5 kg/d during 9 d. Milk yield, BW and feed intake were recorded daily. Blood and milk were sampled every 3 d at the end of each concentrate level. Milk fat, protein, lactose and urea contents were determined. In blood, concentrations of various metabolites, endocrine factors and enzyme activities (e.g. glucose, non-esterified fatty acids (NEFAs), β-hydroxybutyrate, urea, cholesterol, triglycerides, insulin, glucagon, aspartate aminotransferase (ASAT), gamma-glutamyltransferase (GGT) and glutamate dehydrogenase activity (GLDH)) were measured. Milk yield, milk composition and BW were not affected by type and level of concentrates. Feed intake increased in cows with greater amounts of the aminogenic and lipogenic concentrate compared with the glucogenic concentrate. Milk and plasma urea concentrations were elevated in the aminogenic and to a lesser extent in the lipogenic treatment compared with the glucogenic treatment. Glucose concentrations in plasma were not affected by treatments, whereas insulin and glucagon increased, and NEFA concentrations decreased only in cows fed 7.5 kg/d aminogenic concentrate compared with the glucogenic and lipogenic treatment. Activities of ASAT, GGT and GLDH as well as the total antioxidant capacity were not affected by diets. In conclusion, immediate metabolic and endocrine responses were observed due to the short-term dietary changes. Particularly, a surplus of nitrogen supply via the aminogenic diet affected metabolic responses and stimulated insulin and glucagon secretion.

Hepatic effects of rumen-protected branched-chain amino acids with or without propylene glycol supplementation in dairy cows during early lactation

Essential amino acids (EAA) are critical for multiple physiological processes. Branched-chain amino acid (BCAA) supplementation provides energy substrates, promotes protein synthesis, and stimulates insulin secretion in rodents and humans. Most dairy cows face a protein and energy deficit during the first weeks postpartum and utilize body reserves to counteract this shortage. The objective was to evaluate the effect of rumen-protected BCAA (RP-BCAA; 375 g of 27% l-leucine, 85 g of 48% l-isoleucine, and 91 g of 67% l-valine) with or without oral propylene glycol (PG) administration on markers of liver health status, concentrations of nonesterified fatty acids (NEFA) and β-hydroxybutyrate (BHB) in plasma, and liver triglycerides (TG) during the early postpartum period in dairy cows. Multiparous Holstein cows were enrolled in blocks of 3 and randomly assigned to either the control group or 1 of the 2 treatments from calving until 35 d postpartum. The control group (n = 16) received 200 g of dry molasses per cow/d; the RP-BCAA group (n = 14) received RP-BCAA mixed with 200 g of dry molasses per cow/d; the RP-BCAA plus PG (RP-BCAAPG) group (n = 16) received RP-BCAA mixed with 200 g of dry molasses per cow/d, plus 300 mL of PG, once daily from calving until 7 d in milk (DIM). The RP-BCAA and RP-BCAAGP groups, on average (± standard deviation), were predicted to receive a greater supply of metabolizable protein in the form of l-Leu 27.4 ± 3.5 g/d, l-Ile 15.2 ± 1.8 g/d, and l-Val 24.2 ± 2.4 g/d compared with the control cows. Liver biopsies were collected at d 9 ± 4 prepartum and at 5 ± 1 and 21 ± 1 DIM. Blood was sampled 3 times per week from calving until 21 DIM. Milk yield, dry matter intake, NEFA, BHB, EAA blood concentration, serum chemistry, insulin, glucagon, and liver TG and protein abundance of total and phosphorylated branched-chain ketoacid dehydrogenase E1α (p-BCKDH-E1α) were analyzed using repeated measures ANOVA. Cows in the RP-BCAA and RP-BCAAPG groups had lower liver TG and lower activities of aspartate aminotransferase and glutamate dehydrogenase during the first 21 DIM, compared with control. All cows, regardless of treatment, showed an upregulation of p-BCKDH-E1α at d 5 postpartum, compared with levels at 21 d postpartum. Insulin, Met, and Glu blood concentration were greater in RP-BCAA and RP-BCAAPG compared with control during the first 35 DIM. Therefore, the use of RP-BCAA in combination with PG might be a feasible option to reduce hepatic lipidosis in dairy cows during early lactation.

Effects of S-adenosyl methionine and essential phospholipids on serum biochemical parameters in simulated acute liver disease in late pregnancy

AIM: Liver diseases, developing in late pregnancy, remains a very important problem in obstetrics. In present study, the aim was to evaluate the effectiveness of monotherapy by essential phospholipids and by S-adenosyl methionine for simulated acute liver pathology during pregnancy using the biochemical parameters of blood serum.
 STUDY DESIGN AND METHODS: Acute liver injury was simulated in rats from 15th to 18th day of pregnancy using tyloxapol (300 mg / kg daily). As drugs for monotherapy, Essentiale (Sanofi-Aventis, France) and Heptral (Abbott srl, Italy) were used separately and were administered to rats daily from the 16th to the 18th day of pregnancy (50 mg / kg and 35 mg / kg, respectively). On the 19th day of pregnancy, blood serum biochemical parameters were analyzed.
 RESULTS: In the model, the concentrations of triglycerides and cholesterol were sharply increased, which can be caused not only by the inhibitory effect of tyloxapol on the lipoprotein lipase of the lumen of blood vessels, but also by damage to liver cells with the accumulation of lipids in them. The activities of aminotransferases (ALT, AST), glutamate dehydrogenase and lactate dehydrogenase were statistically significantly increased. In healthy pregnant rats, the activity of alkaline phosphatase (ALP) decreased from 15th to 19th day of gestation, but under the treatment by tyloxapol in some cases the increase of ALP activity was observed. After using essential phospholipids in the model of acute liver injury, normal values of ALT and ALP activities were observed, and a significant decrease in triglycerides was revealed, which did not reach the normal values. After using S-adenosyl methionine in this model, the significant changes in blood serum parameters were not observed. By themselves, the drugs change several biochemical parameters in the serum of healthy pregnant rats. Heptral increases urea levels and Essentiale appears to increase AST activity.
 CONCLUSION: The use of essential phospholipids or S-adenosyl methionine as monotherapy in a model of acute liver damage in late pregnancy has demonstrated their low efficiency. It is possible that the combined use of drugs is necessary to increase the effectiveness. The use of S-adenosyl methionine should be carried out under the control of the urea level and glutamate dehydrogenase activity in serum. While using essential phospholipids, it is advisable to control the AST activity.

Ammonium transporter PsAMT1.2 from Populus simonii functions in nitrogen uptake and salt resistance

Ammonium (NH4+) is a primary nitrogen (N) source for many species, and NH4+ uptake is mediated by various transporters. However, the effects of NH4+ transporters on N uptake and metabolism under salt stress remain unclear. In the present study, we investigated the expression characteristics and transport function of PsAMT1.2 in Populus simonii and its role in ammonium uptake and metabolism under salt stress. PsAMT1.2 was localized in the plasma membrane highly expressed in the roots. Heterologous functionality tests demonstrated that PsAMT1.2 mediates NH4+ permeation across the plasma membrane in yeast mutants, restoring growth. A short-term NH4+ uptake experiment showed that PsAMT1.2 is a high-affinity NH4+ transporter with a Km value of 80.603 μM for NH4+. Compared with the wild type (WT, Populus tremula × Populus alba INRA 717-IB4 genotype), PsAMT1.2-overexpressing transgenic poplar grew better, with higher increases in stem height and relative chlorophyll content under both control and salt-stress conditions. PsAMT1.2 overexpression significantly increased the total NH4+ concentration and total N of whole plants under salt stress. The glutamate synthase (GS), glutamine synthetase (GOGAT) and glutamate dehydrogenase (GDH) activities and the total amino acids largely increased in the roots of PsAMT1.2-overexpressing transgenic plants compared with the WT plants under control conditions, suggesting that PsAMT1.2 overexpression promotes NH4+ assimilation and metabolism in poplar roots. Consistent with the increased total amino acid content, GS1.3, GS2 and Fd-GOGAT expression was upregulated in the roots and leaves of the PsAMT1.2-overexpressing transgenic plants compared with the WT plants under salt stress. Collectively, PsAMT1.2 encodes a high-affinity NH4+ transporter crucial to NH4+ uptake and metabolism under salt stress.

Adjunction of the Lipase Inhibitor Orlistat Improves Grape Seed Extract Neuroprotection against Brain Ischemia/Reperfusion Injury in Rats

Abstract: Aim: Stroke is a public health concern for which there is currently no prophylaxis. In this study, we assessed the protective effect of Grape Seed Extract (GSE) and Orlistat (ORL) against brain ischemia/reperfusion (I/R) injury. Methods: Adult male Wistar rats were treated either with GSE (2.5 g/kg), ORL (4 mg/kg) or both drugs for one week and ischemia performed during 30 min by a bilateral common carotid artery occlusion (BCCAO), followed by 60 min reperfusion. Rats were then sacrificed, their whole brain used for infarct size determination using TTC staining or dissected into cortex, hippocampus and cerebellum for biochemical analysis of I/R-induced oxidative stress and energy failure. Results: In the three brain regions of interest, I/R disturbed protein carbonylation, xanthine oxidase (XO), catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities, as well as intracellular mediators as hydrogen peroxide (H2O2), calcium and iron. Furthermore I/R altered energy fueling through the decrease of α-ketoglutarate dehydrogenase (α-KGDH) and fumarase (FH) together with mitochondrial complexes I and II along with glutamatergic excitotoxicity through glutamate dehydrogenase (GDH) and glutamine synthetase (GS) activities into cortex and hippocampal areas but not into cerebellum. In addition I/R affected mitochondrial viability as assessed by MTT staining and the moonlighting apoptosis inducer glyceraldehyde-3- phosphate dehydrogenase (GAPDH). Conclusion: Interestingly, GSE prevented efficiently the deleterious effects of I/R and the best protection was obtained when combining the two drugs, especially within cortex and hippocampus compartments. Thus, adjunction of ORL to GSE treatment is a promising strategy to improve neuroprotection from stroke. Key words: Brain I/R, GSE, Orlistat, Neuroprotection, Energy failure.

Disruption of endoplasmic reticulum homeostasis exacerbates liver injury in clinically ketotic cows

Disruption of endoplasmic reticulum (ER) homeostasis, a condition termed "ER stress," contributes to the development of liver injury in nonruminants. Because liver injury is a prominent pathological feature associated with overproduction of ketone bodies in dairy cows with ketosis, understanding the ER stress state and its functional consequences on liver injury is of particular interest. Here, 30 multiparous cows (within 3 wk postpartum) classified based on blood β-hydroxybutyrate (BHB) as healthy (n = 15, BHB <0.6 mM) or clinically ketotic (n = 15, BHB >3.0 mM) were used. Compared with healthy cows, ketotic cows had greater levels of serum fatty acids and activities of serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, γ-glutamyl transferase, and glutamate dehydrogenase but lower serum glucose. Furthermore, dairy cows with ketosis had greater protein abundance of ER stress markers in liver tissue, including protein kinase RNA-like ER kinase (PERK), inositol-requiring protein-1α (IRE1α), and cleaved activating transcription factor-6 (ATF6). Cows with ketosis also had higher mRNA levels of hepatic 78-kDa glucose-regulated protein (GRP78) and spliced X-box binding protein 1 (sXBP1). These data confirmed an enhanced ER stress state in clinically ketotic cows. To explore whether enhanced hepatic ER stress was induced by elevated ketone bodies and the possible contribution of ER stress to liver injury, in vitro experiments were then performed using isolated primary calf hepatocytes treated with incremental concentrations of BHB (0, 0.6, 1.2, 3.0, and 4.8 mM) for 12 h with or without overexpression of GRP78 (the master regulator of unfolded protein response). Phosphorylation levels of PERK and IRE1α proteins, level of cleaved ATF6 protein, and mRNA abundance of GRP78 and sXBP1 in hepatocytes increased after treatment with high (3.0 and 4.8 mM) BHB, indicating a mechanistic link between excessive BHB and enhanced hepatic ER stress. Furthermore, treatment with 3.0 and 4.8 mM BHB markedly elevated activities of aspartate aminotransferase and alanine aminotransferase in cell supernatant, indicating exacerbated hepatocyte damage after ER stress was enhanced. Overexpression of GRP78 attenuated both BHB-induced ER stress and the ensuing cellular damage, suggesting that hepatocyte damage caused by excessive BHB can be mediated via enhanced ER stress. Overall, the present study revealed that ER stress may exacerbate liver injury development in clinically ketotic cows, underscoring the biological relevance of this pathway in the context of liver injury.

Dietary tryptophan requirement of northern snakehead, Channa argus (Cantor, 1842)

The optimum dietary tryptophan requirement has not been estimated for northern snakehead (Channa argus Cantor, 1842) despite being considered the main limiting essential amino acid in many cereal grain ingredients. A 70-day feeding trial was carried out to determine the dietary tryptophan requirement using 540 juvenile fish (10.21 ± 0.11 g) randomly distributed into 18 net cages with six treatments and three replicates. Six extruded isonitrogenous (48.56% protein) and isoenergetic (19.72 KJ of gross energy g−1) diets containing 0.19%, 0.30%, 0.39%, 0.48%, 0.59% and 0.68% L-tryptophan were prepared. Fish were hand-fed twice daily at apparent satiation level. The results indicated that final weight, weight gain (WG), specific growth rate (SGR), feed efficiency (FE), protein efficiency ratio (PER), the crude protein content in dorsal muscle, glutamate dehydrogenase activity and glutamate oxaloacetate transaminase activity in liver were significantly improved, with increases in dietary tryptophan up to 0.48%. The content of Methionine, Histidine, Threonine, Glycine, Phenylalanine and Glutamic acid in dorsal muscle of fish was also markedly affected by the dietary tryptophan levels. On the other hand, fish fed with 0.39% dietary tryptophan had the highest pepsin activity, which was significantly higher than that in fish fed with 0.59% and 0.68% dietary tryptophan, however, the glutamate pyruvate transaminase activity significantly increased until the dietary tryptophan level increased to 0.68%. Based on the second-degree polynomial regression analysis of SGR and FE against dietary tryptophan levels, the optimum dietary tryptophan requirement for C. argus was respectively estimated to be 0.46% and 0.45% of the diet, corresponding to 0.95% and 0.93% of dietary protein.

Hepatogenous photosensitisation in cows grazing turnips (Brassica rapa) in South Africa.

Holstein cows on a farm in the Humansdorp district, Eastern Cape province, South Africa, developed reddened, painful teat skin 3 days after grazing a mixed forage crop dominated by bulb turnip (Brassica rapa, Barkant cultivar). The crop was grazed 45 days after planting and 10% of the herd developed symptoms. More characteristic non-pigmented skin lesions started manifesting 1–2 days after the appearance of the teat lesions. Affected cows had elevated serum activities of gamma-glutamyl transferase, glutamate dehydrogenase and aspartate aminotransferase. These blood chemistry findings confirmed a secondary (hepatogenous) photosensitivity. As a result of the severity of the teat and skin lesions, seven cows were slaughtered and tissue samples from five of them were collected for histopathological examination. Liver lesions in cows that were culled 3 or more weeks after the onset of the outbreak showed oedematous concentric fibrosis around medium-sized bile ducts and inflammatory infiltrates in portal tracts. Characteristic lesions associated with other known hepatobiliary toxicities were not found. No new cases were reported 5 days after the cattle were removed from the turnips. The sudden introduction of the cows, without any period of transitioning or adaptation to grazing turnips, as well as the short latent period, clinical signs of photosensitisation, blood chemistry and histopathology, confirmed a diagnosis of Brassica-associated liver disease, a condition seen in New Zealand but not previously described in South Africa. Brassica forage crops are potentially toxic under certain conditions and farmers must be aware of these risks.