Concurrent Ammonia Synthesis and Alcohol Oxidation Boosted by Glutathione-Capped Quantum Dots under Visible Light

Mother nature accomplishes efficient ammonia synthesis via cascade N2 oxidation by lightning strikes followed with enzyme-catalyzed nitrogen oxyanion (NOx -, x = 2,3) reduction. The protein environment of enzymatic centers for NOx --to-NH4 + process greatly inspires the design of glutathione-capped (GSH) quantum dots (QDs) for ammonia synthesis under visible light (440 nm) in tandem with plasma-enabled N2 oxidation. Mechanistic studies reveal that GSH induces positive shift of surface charge to strengthen the interaction between NOx - and QDs. Upon visible light irradiation of QDs, the balanced and rapid hole and electron transfer furnish GS·radicals for 2e-/2H+ alcohol oxidation and H·for 8e-/10H+ NO3 --to-NH4 + reduction simultaneously. For the first time, mmol-scale ammonia synthesis is realized with apparent quantum yields of 5.45% ± 0.64%, and gram-scale synthesis of value-added acetophenone and NH4Cl proceeds with 1:4 stoichiometry and stability, demonstrating promising multielectron and multiproton ammonia synthesis efficiency and sustainability with nature-inspired artificial photocatalysts.

Research and application of a new multilevel fuzzy comprehensive evaluation method for cold stress in dairy cows

Effective and comprehensive evaluation of cold stress is critical for healthy dairy cow breeding in the winter. Previous studies on dairy cow cold stress have considered thermal environmental factors but not physiological factors or air quality. Therefore, this study aimed to propose a multilevel fuzzy comprehensive evaluation (FCE) method for cold stress in dairy cows based on the analytic hierarchy process (AHP) and a genetic algorithm (GA). First, the AHP was used to construct an evaluation index system for cold stress in dairy cows from 3 dimensions: thermal environment (temperature, relative humidity, wind speed, and illumination), physiological factors (respiratory rate, body surface temperature), and air quality [NH₃, CO₂, inhalable particulate matter (PM₁₀)]. Second, the consistency test of the judgment matrix was transformed into a nonlinear constrained optimization problem and solved using the GA. Next, based on fuzzy set theory, the comment set and membership function were established to classify the degree of cold stress into 5 levels: none, mild, moderate, high, and extreme. Then, the degree of cold stress in cows was obtained using multilevel fuzzy comprehensive judgment. To investigate the effect of illumination indicators on cold stress in dairy cows, 24 prelactation cows from the south and north sides were selected for a 117-d comprehensive cold stress evaluation. The results showed that the mean mild cold stress durations were 605.3 h (25.22 d) and 725.5 h (30.23 d) and the moderate cold stress durations were 67.2 h (2.8 d) and 96 h (4.0 d) on the south and north sides, respectively. Simultaneously, generalized linear mixed model showed that there were significant correlations between the daily cold stress duration and milk yield, feeding time, lying time, and active steps in the cows on both sides. This method can reasonably indicate cow cold stress conditions and better guide cold protection practices in actual production.

Effects of dietary supplementation of gestating sows with adenosine 5 '-monophosphate or adenosine on placental angiogenesis and vitality of their offspring

Our previous study found that dietary nucleotide supplementation, including adenosine 5 '-monophosphate (AMP), could increase AMP content in sow milk and promote piglet growth, but its effects on placental efficiency and piglet vitality remains unknown. This experiment aimed to investigate the effects of dietary AMP or its metabolite adenosine (ADO) supplementation on sow reproductive performance and placental angiogenesis. A total of 135 sows with a similar farrowing time were blocked by backfat and body weight (BW) at day 65 of gestation, and assigned to 1 of 3 dietary treatment groups (n = 45 per treatment): basal diet, basal diet supplemented with 0.1% AMP, or 0.1% ADO, respectively. Placental analysis and the characteristics of sows and piglets unveiled that compared with control (CON) group, AMP or ADO supplementation could improve sow placental efficiency (P<0.05) and newborn piglet vitality (P<0.05), increase piglet birth weight (P<0.05), and reduce stillbirth rate (P<0.05). More importantly, AMP or ADO supplementation could increase the contents of AMP, ADO, and their metabolites in placentae (P<0.05). Meanwhile, AMP or ADO supplementation could also increase placental vascular density (P<0.05) and the expression of vascular endothelial growth factor A (P<0.05), as well as promote the migration and tube formation of porcine iliac artery endothelial cells (P<0.05). Overall, maternal dietary AMP or ADO supplementation could increase their contents in the placenta, thereby improving placental angiogenesis and neonatal piglet vitality.

Luminescent carbon dots with concentration-dependent emission in solution and yellow emission in solid state

Carbon dots (CDs) is a class of zero-dimensional carbon nanomaterials with favorable stability and optical properties. However, CDs in solid state often suffer from fluorescence quenching due to π-π stacking of conjugated systems, like most small molecules or organic dyes. Herein, we prepared the CDs that generate bright yellow luminescence in solid state without any additional matrix, meanwhile the solid CDs are inclined to assembly into spherical structure. While the CDs are dissolved in aqueous solution, the photoluminescence (PL) emission from blue to green can be realized by regulating the concentration of CDs. With the concentration increasing, the self-assembly behavior of CDs is observed in solution, which leads to the bathochromic shift of photoluminescence. Besides, the mechanism of PL conversion in this process was proposed based on the characterization results, that with the concentration of CDs rising in solution, π-π interaction was restrained while electron redistribution was induced. Consequently, a localized state II caused by electron rearrangement gradually becomes the predominant emission state, resulting in the PL emission shifting to long-wavelength region. Moreover, CDs have shown favorable potentials in the field of anti-counterfeit and multicolor bioimaging, making the CDs highly attractive for a wide variety of applications.

Review: The roles and functions of glutamine on intestinal health and performance of weaning pigs

The gut is composed of a single layer of intestinal epithelial cells and plays important roles in the digestion and absorption of nutrients, immune and barrier functions and amino acid metabolism. Weaning stress impairs piglet intestinal epithelium structural and functional integrities, which results in reduced feed intake, growth rates and increased morbidity and mortality. Several measures are needed to maintain swine gut development and growth performance after weaning stress. A large body of evidence indicates that, in weaning piglets, glutamine, a functional amino acid, may improve growth performance and intestinal morphology, reduce oxidative damage, stimulate enterocyte proliferation, modulate cell survival and death and enhance intestinal paracellular permeability. This review focuses on the effects of glutamine on intestinal health in piglets. The aim is to provide evidentiary support for using glutamine as a feed additive to alleviate weaning stress.

Stages of pregnancy and weaning influence the gut microbiota diversity and function in sows

Aims

The gut microbiota is believed to play important roles in the health of pregnant mammals, including their nutrient metabolism, immune programming and metabolic regulation. However, until recently, the shifts in gut microbiota composition and faecal and blood metabolic activity during different stages of pregnancy had not been investigated.

Methods and Results

We investigated the shifts in backfat thickness, plasma and faecal metabolites and gut microbiota on days 30, 60, 90 and 110 of pregnancy and on day 21 after parturition (weaning) in sows. The backfat thickness of sows did not significantly differ among the different stages of pregnancy. The plasma concentrations of lipid metabolites, including triacylglycerol (TG), total cholesterol, high‐density lipoprotein‐cholesterol, low‐density lipoprotein‐cholesterol and calcium were reduced (P < 0·05) during pregnancy. In addition, the concentration of these metabolites, except TG, reached their maximum at the time of weaning. We also found that Tenericutes, Fibrobacteres and Cyanobacteria varied significantly according to the stages of pregnancy in sows (P < 0·05). Most of the genera, such as Clostridiales, Desulfovibrio, Mogibacteriaceae and Prevotella, increased (P < 0·05) with the progression of pregnancy and decreased (P < 0·05) at weaning. The alpha diversity values (i.e., Shannon diversity and observed species) of sow gut microbiota increased (P < 0·05) from pregnancy to weaning. Pregnancy stages also significantly influenced (P < 0·05) the community structure (beta diversity) of gut microbiota. The progression of pregnancy was associated with changes in lipid metabolism and several carbohydrate‐degradation bacteria (i.e., Prevotella, Succinivibrio, Bacteroides and Parabacteroides).

Conclusions

Although causal links between the measured parameters remain hypothetical, these findings suggest that the increased diversity and concentration of beneficial gut microbes are associated with the metabolism of pregnant sows.

Significance and Impact of the Study

Manipulation of the sow gut microbiota composition may potentially influence metabolism and health during pregnancy.

[Clinical effect and safety of pegylated interferon-α-2b injection (Y shape, 40 kD) in treatment of HBeAg-positive chronic hepatitis B patients]

Objective: To investigate the clinical effect and safety of long-acting pegylated interferon-α-2b (Peg-IFN-α-2b) (Y shape, 40 kD) injection (180 μg/week) in the treatment of HBeAg-positive chronic hepatitis B (CHB) patients, with standard-dose Peg-IFN-α-2a as positive control. Methods: This study was a multicenter, randomized, open-label, and positive-controlled phase III clinical trial. Eligible HBeAg-positive CHB patients were screened out and randomized to Peg-IFN-α-2b (Y shape, 40 kD) trial group and Peg-IFN-α-2a control group at a ratio of 2:1. The course of treatment was 48 weeks and the patients were followed up for 24 weeks after drug withdrawal. Plasma samples were collected at screening, baseline, and 12, 24, 36, 48, 60, and 72 weeks for centralized detection. COBAS® Ampliprep/COBAS® TaqMan® HBV Test was used to measure HBV DNA level by quantitative real-time PCR. Electrochemiluminescence immunoassay with Elecsys kit was used to measure HBV markers (HBsAg, anti-HBs, HBeAg, anti-HBe). Adverse events were recorded in detail. The primary outcome measure was HBeAg seroconversion rate after the 24-week follow-up, and non-inferiority was also tested. The difference in HBeAg seroconversion rate after treatment between the trial group and the control group and two-sided confidence interval (CI) were calculated, and non-inferiority was demonstrated if the lower limit of 95% CI was > -10%. The t-test, chi-square test, or rank sum test was used according to the types and features of data. Results: A total of 855 HBeAg-positive CHB patients were enrolled and 820 of them received treatment (538 in the trial group and 282 in the control group). The data of the full analysis set showed that HBeAg seroconversion rate at week 72 was 27.32% in the trial group and 22.70% in the control group with a rate difference of 4.63% (95% CI -1.54% to 10.80%, P = 0.1493). The data of the per-protocol set showed that HBeAg seroconversion rate at week 72 was 30.75% in the trial group and 27.14% in the control group with a rate difference of 3.61% (95% CI -3.87% to 11.09%, P = 0.3436). 95% CI met the non-inferiority criteria, and the trial group was non-inferior to the control group. The two groups had similar incidence rates of adverse events, serious adverse events, and common adverse events. Conclusion: In Peg-IFN-α regimen for HBeAg-positive CHB patients, the new drug Peg-IFN-α-2b (Y shape, 40 kD) has comparable effect and safety to the control drug Peg-IFN-α-2a.

Role of surface charge on the interaction between carbon nanodots and human serum albumin

Carbon nanodots (Cdots) have aroused widespread concerns in the field of biomedical applications. In order to achieve better implications of behavior of Cdots in the biological environment, an array of spectroscopic, electrochemical and calorimetric techniques were performed to study the interaction of Cdots possessing different charges with human serum albumin (HSA) in physiological condition. Two polymer, polyethylene glycol (PEG) and polyetherimide (PEI), were applied to passivate the bare Cdots to achieve the Cdots with different surface charge, namely negatively charged PEG Cdots and positively charged PEI Cdots. The fluorescence of HSA was obviously quenched by both Cdots in a charge-independent behavior through a dynamic collision mechanism. Moreover, the association affinity of PEG Cdots or PEI Cdots bound to HSA was very close to each other. In addition, PEG Cdots with diverse content exhibited little effects on the secondary structure of HSA while only high content of PEI Cdots induced obvious conformation perturbation of HSA. The electrostatic forces dominate the association between HSA and PEI Cdots while the association of PEG Cdots to HSA is initiated by hydrophobic and van der Waals forces. Furthermore, the results of isothermal titration calorimetry revealed that both the interaction was driven by favorable entropy and enthalpy, which confirmed that these association processes are thermodynamically spontaneous. Finally, the sites marker competitive experiment showed that the association sites of Cdots with HSA exhibit a charge dependent manner, namely PEG Cdots effectively occupy the site I of HSA while the association sites of PEI Cdots are mainly located in site II.

Low-protein diet improves meat quality of growing and finishing pigs through changing lipid metabolism, fiber characteristics, and free amino acid profile of the muscle

The objective of the study was to investigate the effect of feeding reduced CP, AA-supplemented diets on meat quality in growing and finishing pigs as well as the related mechanism. In experiment 1, 18 growing pigs (36.5 kg BW) were assigned randomly and fed 1 of 3 corn-soybean meal diets containing either 18% CP (normal protein, NP), 15% CP (low protein, LP), or 12% CP (very low protein, VLP). In experiment 2, 18 finishing pigs (62.3 kg BW) were allotted randomly into 1 of the following diets: 16% CP (NP), 13% CP (LP), or 10% CP (VLP). In both experiments, the LP and VLP diets were supplemented with crystalline AA to achieve equal content of standardized ileal digestible lysine, methionine, threonine, and tryptophan. At the end of each experiment, all pigs were slaughtered to collect longissimus dorsi muscle (LM) samples. Samples were used for determining meat quality, intramuscular fat (IMF) content, fatty acid composition, free AA profile, and expression of genes for myosin heavy chain isoforms. Results showed that growing and finishing pigs fed the LP diets increased (P < 0.05) redness value of LM, while finishing pigs fed the LP and VLP diets decreased (P < 0.05) the shear force values. Compared with the NP diet, growing and finishing pigs fed lower CP diets had higher (P < 0.05) contents of IMF and MUFA, and lower (P < 0.05) contents of PUFA. Besides, higher (P < 0.05) expression levels of type I and/or IIa muscle fibers were observed in LP diet-fed growing and finishing pigs, and greater concentrations of taurine and tasty AA in VLP diet-fed growing and finishing pigs. Taken together, our results indicate that low-protein diets could positively affect meat quality of growing and finishing pigs, and likely through regulation of IMF content and fatty acid composition, fiber characteristics, and free AA profile in the muscle.

Dietary supplementation with arginine and glutamic acid enhances key lipogenic gene expression in growing pigs

Our previous study showed dietary supplementation with Arg and Glu increased intramuscular fat deposition and decreased back fat thickness in pigs, suggesting that the genes involved in lipid metabolism might be regulated differently in muscle and s.c. adipose (SA) tissues. Sixty Duroc × Large White × Landrace pigs with an average initial BW of 77.1 ± 1.3 kg were randomly assigned to 1 of 5 treatment groups (castrated male to female ratio = 1:1). Pigs in the control group were fed a basic diet, and those in experimental groups were fed the basic diet supplemented with 2.05% alanine (isonitrogenous group), 1.00% arginine (Arg group), 1.00% glutamic acid + 1.44% alanine (Glu group), or 1.00% arginine + 1.00% glutamic acid (Arg+Glu group). Fatty acid percentages and mRNA expression levels of the genes involved in lipid metabolism in muscle and SA tissues were examined. The percentages of C14:0 and C16:0 in the SA tissue of Glu group pigs and C14:0 in the longissimus dorsi (LD) muscle of Glu and Arg+Glu groups decreased ( < 0.05) compared to the basic diet group. The Arg+Glu group showed the highest ( < 0.05) hormone-sensitive lipase expression level in SA tissue and higher ( < 0.05) mRNA levels of in the LD muscle than the basic diet and isonitrogenous groups. Additionally, the mRNA level of fatty acid synthase in the Arg+Glu group was more upregulated ( < 0.05) than that of the Arg group. An increase in the mRNA level of in the biceps femoris muscle was also observed in the Arg+Glu group ( < 0.05) compared with the basic diet and isonitrogenous groups. Collectively, these findings suggest that dietary supplementation with Arg and Glu upregulates the expression of genes involved in adipogenesis in muscle tissues and lipolysis in SA tissues.

Dietary supplementation with arginine and glutamic acid modifies growth performance, carcass traits, and meat quality in growing-finishing pigs

Sixty Duroc × Large White × Landrace pigs with an average initial BW of 77.1 ± 1.3 kg were used to investigate the effects of dietary supplementation with arginine and glutamic acid on growth performance, carcass traits, and meat quality in growing-finishing pigs. The animals were randomly assigned to 1 of 5 treatment groups (12 pigs/group, male:female ratio 1:1). The pigs in the control group were fed a basal diet (basal diet group), and those in the experimental groups were fed the basal diet supplemented with 2.05% -alanine (isonitrogenous group), 1.0% -arginine (Arg group), 1% glutamic acid + 1.44% -alanine (Glu group), or 1.0% -arginine + 1.0% glutamic acid (Arg+Glu group). After a 60-d period of supplementation, growth performance, carcass traits, and meat quality were evaluated. The results showed no significant differences ( > 0.05) in growth performance and carcass traits of the pigs in the Arg group relative to the basal diet group; however, the longissimus dorsi (LD) muscle and back fat showed a decrease ( < 0.05) in the percentage of SFA. In the Glu group, the final BW, phase 1 (d 1 to 30) and phase 2 (d 31 to 60) ADFI, and average back fat thickness of the pigs decreased ( < 0.05) by 7.14%, 23.43%, 8.03%, and 33.88%, respectively, when compared with the basal diet group. Dietary Arg+Glu supplementation had no effect ( > 0.05) on the final BW, phase 2 ADFI, and average daily weight gain in pigs but decreased ( < 0.05) their phase 1 ADFI, average back fat thickness, and percentage of SFA in the LD muscle and back fat, and increased ( < 0.05) the i.m. fat (IMF) content of the LD and biceps femoris muscles when compared with the basal diet group. Furthermore, a 16% decrease in yellowness (b* value; < 0.05) was observed in the Arg+Glu group pigs when compared with the isonitrogenous group. These findings suggest that dietary supplementation with both Arg and Glu beneficially increases the IMF deposition and improves the meat color and fatty acid composition without affecting growth performance and s.c. fat in pigs, providing a novel strategy to enhance meat quality in growing-finishing pigs.

Short-term supplementation of isocaloric meals with L-tryptophan affects pig growth

L-Tryptophan (Trp) and some of its metabolites regulate the circadian rhythm in mammals. We aimed to investigate the effects of short-term supplementation of Trp in isocaloric meals on growth performance using the parameters of multiple blood biomarkers and free amino acids in growing pigs. A total of 32 Landrace × Yorkshire barrows with a mean body weight of 8.64 (±1.13) kg were randomly assigned to four groups and then fed with various concentrations of Trp diets daily. Our results showed that sequential supplementation of different concentrations of Trp in isocaloric meals decreased the feed:gain (F:G) ratio (P = 0.079) and plasma urea and albumin (P = 0.019), whereas the level of total protein did not. Among the essential and conditionally essential amino acids, the concentrations of histidine, isoleucine, proline, threonine, arginine, and valine in the plasma decreased (P < 0.05), whereas the concentrations of Trp, glycine, serine, and methionine increased (P < 0.01). In addition, concentrations of branched chain amino acids also significantly decreased (P = 0.004), while the rate of conversion of Trp to branched chain amino acids increased (P < 0.001). Taken together, we show that administration of a high concentration of Trp in breakfast with decreasing concentrations of Trp in lunch and dinner positively affected feed utilization and improved feed efficiency, at least in part, through the optimization of amino acid interconversions and nitrogen utilization.

Metabolic profiles in the response to supplementation with composite antimicrobial peptides in piglets challenged with deoxynivalenol

Deoxynivalenol (DON) causes various toxic effects in human and animals. However, our previous studies have shown that composite antimicrobial peptides (CAP) can have a protective effect in piglets challenged with DON. This study was conducted to evaluate the effect of the CAP GLAM 180# on the metabolism of piglets challenged with DON using a nuclear magnetic resonance (NMR)-based metabolomics approach. A total of 28 individually housed piglets (Duroc × Landrace × Large Yorkshire) weaned at 28 d of age were randomly assigned into 4 treatment groups (7 pigs/treatment) based on a 2 × 2 factorial arrangement that were fed, respectively, a basal diet (NC), basal diet + 0.4% CAP (basal + CAP), basal diet + 4 mg/kg DON (basal + DON), and basal diet + 4 mg/kg DON + 0.4% CAP (DON + CAP). A 7-d adaptation period was followed by 30 d of treatment. Blood samples were then collected for metabolite analysis by proton NMR (H-NMR) spectroscopy and liquid chromatography tandem mass spectrometry (LC-MS/MS). The combined results of H-NMR spectroscopy and LC-MS/MS showed that DON increased ( < 0.05) the serum concentrations of low-density lipoprotein, glycoprotein, urea, trimethylamine-N-oxide (TMAO), and lactate as well as those of almost all essential AA and some nonessential AA but decreased the concentrations of high-density lipoprotein (HDL), unsaturated lipids, citrate, choline, and fumarate compared with those in NC treatment ( < 0.05). There was a significant interaction effect ( < 0.05) of supplementation with DON and CAP on some metabolites showed that the serum concentrations of HDL, unsaturated lipids, Pro, citrate, and fumarate were greater ( < 0.05) whereas those of glycoprotein, urea, TMAO, Gly, and lactate were lower in the DON + CAP treatment compared with those in the basal + DON treatment ( < 0.05). These findings indicated that DON causes disturbances in AA, lipid, and energy metabolism and that CAP could partially attenuate the above metabolic disturbances induced by DON.

Reduced dietary protein level influences the free amino acid and gene expression profiles of selected amino acid transceptors in skeletal muscle of growing pigs

This study was conducted to evaluate the effect of reduced dietary protein level on growth performance, muscle mass weight, free amino acids (FAA) and gene expression profile of selected amino acid transceptors in different fibre type of skeletal muscle tissues (longissimus dorsi, psoas major, biceps femoris) of growing pigs. A total of 18 cross-bred growing pigs (Large White × Landrace × Duroc) with initial body weight (9.57 ± 0.67 kg) were assigned into three dietary treatments: 20% crude protein (CP) diet (normal recommended, NP), 17% CP diet (low protein, LP) and 14% CP diet (very low protein, VLP). The results indicated improved feed-to-gain ratio was obtained for pigs fed LP and NP diets (p < 0.01), while the pigs fed VLP diet showed the worst growth performance (p < 0.01). There was no significant difference in the weights of longissimus dorsi and psoas major muscle between LP and NP groups (p > 0.05). Majority of the determined FAA concentration of LP group were greater than or equal to those of NP group in both longissimus dorsi and psoas major muscle (p < 0.01). Further, the mRNA expression levels of sodium-coupled neutral amino acid transceptor 2, L-type amino acid transceptor 1 and proton-assisted amino acid transceptors 2 were higher in skeletal muscle tissue in LP group compared to those of the pigs fed NP or VLP diet. These results suggested that reduced dietary protein level (3 points of percentage less than recommended level) would upregulate the mRNA expression of amino acid transceptors to enhance the absorption of FAA in skeletal muscle of growing pigs. There seems to be a relationship between response of AA transceptors to the dietary protein level in skeletal muscle tissue of different fibre type. To illustrate the underlying mechanisms will be beneficial to animal nutrition.

Oral administration of putrescine and proline during the suckling period improves epithelial restitution after early weaning in piglets

Polyamines are necessary for normal integrity and the restitution after injury of the gastrointestinal epithelium. The objective of this study was to investigate the effects of oral administration of putrescine and proline during the suckling period on epithelial restitution after early weaning in piglets. Eighteen neonatal piglets (Duroc × Landrace × Large Yorkshire) from 3 litters (6 piglets per litter) were assigned to 3 groups, representing oral administration with an equal volume of saline (control), putrescine (5 mg/kg BW), and proline (25 mg/kg BW) twice daily from d 1 to weaning at 14 d of age. Plasma and intestinal samples were obtained 3 d after weaning. The results showed that oral administration of putrescine or proline increased the final BW and ADG of piglets compared with the control (P < 0.05). Proline treatment decreased plasma D-lactate concentration but increased the villus height in the jejunum and ileum, as well as the percentage of proliferating cell nuclear antigen (PCNA) positive cells and alkaline phosphatase (AKP) activity in the jejunal mucosa (P < 0.05). The protein expressions for zonula occludens (ZO-1), occludin, and claudin-3 (P < 0.05) but not mRNA were increased in the jejunum of putrescine- and proline-treated piglets compared with those of control piglets. The voltage-gated K+ channel (Kv) 1.1 protein expression in the jejunum of piglets administrated with putrescine and the Kv1.5 mRNA and Kv1.1 protein levels in the ileum of piglets administrated with proline were greater than those in control piglets (P < 0.05). These findings indicate that polyamine or its precursor could improve mucosal proliferation, intestinal morphology, as well as tight junction and potassium channel protein expressions in early-weaned piglets, with implications for epithelial restitution and barrier function after stress injury.

Pyrrolidine dithiocarbamate restores gastric damages and suppressive autophagy induced by hydrogen peroxide

It is well known that gastric barrier is very important for protecting host from various insults. Simultaneously, autophagy serving as a prominent cytoprotective and survival pathway under oxidative stress conditions is being increasingly recognized. Thus, this study was conducted for investigating the effect of pyrrolidine dithiocarbamate (PDTC) on gastric barrier function and autophagy under oxidative stress induced by intragastric administration of hydrogen peroxide (H2O2). The gastric tight junction proteins [zonula occludens-1 (ZO1), occludin, and claudin1], autophagic proteins [microtubule-associated protein light chain 3I(LC3I), LC3II, and beclin1], and nuclear factor kappa B (NF-κB) signaling pathway (p65 and IκB kinase α/β) were determined by Western blot. The results showed that H2O2 exposure disturbed gastric barrier function with decreased expression of ZO1, occludin, and claudin1, and reduced gastric autophagy with decreased conversion of LC3I into LC3II in mice. However, treatment with PDTC restored these adverse effects evidenced by increased expression of ZO1 and claudin1 and increased conversion of LC3I into LC3II. Meanwhile, H2O2 exposure decreased normal human gastric epithelial mucosa cell line (GES-1) viability in a concentration-dependent way. However, after being exposed to H2O2, GES-1 exhibited autophagic response which was inconsistent with our in vivo results in mice, while PDTC failed to decrease autophagy in GES-1 induced by H2O2. Simultaneously, the beneficial effect of PDTC on gastric damage and autophagy in mice might be independent of inhibition of NF-κB. In conclusion, PDTC treatment restores gastric damages and reduced autophagy induced by H2O2. Therefore, PDTC may serve as a potential adjuvant therapy for gastric damages.

Protective effect of ultrafiltered XinMaiJia extract against H₂O₂-induced injury in human umbilical vein endothelial cells through NHE1 downregulation

We examined the protective effects of ultrafiltered XinMaiJia (XMJ) extract in a hydrogen peroxide (H2O2)-induced injury model in human umbilical vein endothelial cells (HUVECs) and determined the corresponding changes in the Na(+)-H(+) exchanger (NHE1) protein content and NHE1 gene expression. H2O2-induced HUVECs were treated with different concentrations of XMJ extract and the corresponding changes in morphology, activity, membrane permeability, biochemical indicators, cytokine concentration, NHE1 protein content, and NHE1 gene expression were determined. H2O2 significantly promoted HUVEC injury, whereas ultrafiltered XMJ extract significantly improved the morphological changes in injured HUVECs, increased their activity, and decreased NHE1 gene and protein expression, as well as limited the decrease in membrane permeability and expression of intercellular adhesion molecule-1, vascular cell adhesion molecule-1, interleukin (IL)-1, IL-6, and nuclear factor-kB. Ultrafiltered XMJ extract inhibited H2O2-induced HUVEC injury by inhibiting NHE1 activity.

Feeding a diet containing resistant potato starch influences gastrointestinal tract traits and growth performance of weaned pigs

The aim was to evaluate the effects of feeding resistant potato starch (RPS) as a natural source of resistant starch to weaned pigs for 28 d immediately after weaning. Sixty piglets (Yorkshire-Landrace × Duroc) weaned at 21 ± 2 d (1:1 male:female) with an initial BW of 7.2 ± 0.78 kg were assigned in a completely randomized design to 1 of 5 dietary treatments to give 6 observations per treatment and 2 pigs per pen. Dietary treatments consisted of a negative control corn-soybean meal-wheat-wheat middlings-based diet (NC; no antimicrobial agents added) or the NC supplemented with RPS either as powder or in capsules and each included at 0.5 or 1.0% as a top-dressing on each day. Diets were formulated to meet 1998 NRC specifications. Pigs were offered the experimental diets on an ad libitum basis for 28 d and water was available at all times. The ADG, ADFI, and G:F were determined weekly. Fecal score was determined daily for 14 d after weaning. At the conclusion of study, 1 pig from each pen was randomly selected and euthanized (n = 6 per treatment) to determine visceral organ weight, digesta pH, VFA, and ammonia N (NH3-N) concentrations. Resistant potato starch supplementation improved (P < 0.001) fecal score, and pigs offered 1.0% RPS had more solid feces (P < 0.05) than those offered 0.5% RPS during the first 14 d after weaning, independent of the form of RPS. Resistant potato starch supplementation decreased (P < 0.05) ileal and cecal digesta pH regardless of the levels of RPS or mode of delivery. The total VFA concentrations in cecal digesta were greater (P < 0.05) but the molar proportion of branched-chain fatty acids were lower (P < 0.05) for pigs fed the RPS-containing diets compared with those fed the NC, irrespective of the RPS levels or the form of RPS. However, there were no differences (P > 0.10) in visceral organ weights, growth performance, and digestibilities of DM, CP, Ca, and P among treatments. The results of this experiment indicate that supplementing a weaner pig diet with at least 0.5% RPS independent of mode of delivery has the potential to enhance outcomes characteristic of a functional gut in weaned pigs without adverse effects on growth.

Effects of composite antimicrobial peptides in weanling piglets challenged with deoxynivalenol: I. Growth performance, immune function, and antioxidation capacity

The mycotoxin deoxynivalenol (DON) is a food contaminant that leads to reduced feed intake and reduced BW gain, as well as organ impairment. On the other hand, antimicrobial peptides have been shown to have positive effects on growth performance, nutrient digestibility, and immune function. The purpose of this study was to investigate the protective effects of composite antimicrobial peptides (CAP) on piglets challenged with DON. After a 7-d adaptation period, 28 individually housed piglets (Duroc × Landrace × Large Yorkshire) weaned at 28 d of age were randomly assigned to receive 1 of 4 treatments (7 pigs/treatment): negative control, basal diet (NC), basal diet + 0.4% CAP (CAP), basal diet + 4 mg/kg DON (DON), and basal diet + 4 ppm DON + 0.4% CAP (DON + CAP). On d 15 and 30 after the initiation of treatment, blood samples were collected for the determination of blood profile. Piglets were monitored for 30 d to assess performance and then were slaughtered to obtain organs for the determination of the relative weight of organs. The results showed that dietary supplementation with DON decreased (P < 0.05) ADFI, ADG, and G:F, whereas dietary supplementation with CAP improved ADG and G:F (P < 0.05). The relative weight of the kidney and pancreas was greater and the relative weight of the spleen was lighter in the DON treatment than in the other 3 treatments (P < 0.05). There were no effects (P > 0.05) on other relative weights of viscera, except the relative weight of the gallbladder, but the diamine oxidase activity in the liver decreased in DON-treated piglets (P < 0.05). Piglets in the DON treatment had increased serum concentrations of alkaline phosphatase, alanine transaminase, and aspartate aminotransferase and a dramatic decrease in total protein (P < 0.05), whereas there were no differences (P > 0.05) between the DON + CAP treatment and the other treatments. The DON treatment decreased the numbers of red blood cells and platelets, as well as the serum catalase concentrations, and decreased the serum concentrations of H2O2, maleic dialdehyde, and nitric oxide (P < 0.05). The numbers of platelets and thrombocytocrit, as well as the serum concentrations of catalase, were greater, whereas the maleic dialdehyde concentrations were decreased, in both the CAP and DON + CAP treatments compared with the other treatments (P < 0.05). Compared with the control treatment, DON decreased peripheral lymphocyte proliferation on d 15, whereas supplementation with CAP increased it on d 15 and 30 (P < 0.05). These findings indicate that CAP could improve feed efficiency, immune function, and antioxidation capacity and alleviate organ damage, and thus, it has a protective effect in piglets challenged with DON.

Effects of composite antimicrobial peptides in weanling piglets challenged with deoxynivalenol: II. Intestinal morphology and function

Deoxynivalenol (DON) affects animal and human health and targets the gastrointestinal tract. The objective of this study was to evaluate the ability of composite antimicrobial peptides (CAP) to repair intestinal injury in piglets challenged with DON. A total of 28 piglets (Duroc × Landrace × Large Yorkshire) weaned at 28 d of age were randomly assigned to receive 1 of 4 treatments (7 pigs/treatment): negative control, basal diet (NC), basal diet + 0.4% composite antimicrobial peptide (CAP), basal diet + 4 mg/kg DON (DON), and basal diet + 4 mg/kg DON + 0.4% CAP (DON + CAP). After an adaptation period of 7 d, blood samples were collected on d 15 and 30 after the initiation of treatment for determinations of the concentrations of D-lactate and diamine oxidase. At the end of the study, all piglets were slaughtered to obtain small intestines for the determination of intestinal morphology, epithelial cell proliferation, and protein expression in the mammalian target of rapamycin (mTOR) signaling pathway. The results showed that DON increased serum concentrations of D-lactate and diamine oxidase, and these values in the CAP and DON + CAP treatments were less than those in the NC and DON treatments, respectively (P < 0.05). The villous height/crypt depth in the jejunum and ileum and the goblet cell number in the ileum in the CAP and DON + CAP treatments were greater than those in the NC and DON treatments (P < 0.05). The proliferating cell nuclear antigen (PCNA) labeling indexes for the jejunum and ileum in the DON + CAP treatment were greater than those in the DON treatment (P < 0.05). The DON decreased (P < 0.05) the relative protein expression of phosphorylated Akt (Protein Kinase B) and mTOR in the jejunal and ileal mucosa and of phosphorylated 4E-binding protein 1 (p-4EBP1) in the jejunal mucosa, whereas CAP increased (P < 0.05) the protein expression of p-4EBP1 in the jejunum. These findings showed that DON could enhance intestinal permeability, damage villi, cause epithelial cell apoptosis, and inhibit protein synthesis, whereas CAP improved intestinal morphology and promoted intestinal epithelial cell proliferation and protein synthesis, indicating that CAP may repair the intestinal injury induced by DON.

Dietary supplementation with N-carbamylglutamate increases the expression of intestinal amino acid transporters in weaned Huanjiang mini-pig piglets

Weaning is associated with reduced intestinal absorptive capacity in piglets. Our previous study indicated that dietary supplementation with N-carbamylglutamate (NCG) enhanced growth performance and improved intestinal function in weaned piglets. The present study was conducted to test the hypothesis that dietary supplementation with NCG may increase the growth performance of weaned piglets by regulating the expression of intestinal nutrient transporters, thus enhancing nutrient absorption. Twenty-four Huanjiang mini-pig piglets weaned at 21 d of age (3.17 ± 0.21 kg average BW) were randomly assigned to 2 dietary treatments consisting of a basal diet and the basal diet with 0.1% NCG supplementation for a 14-d period with 6 pens per treatment and 1 male and 1 female per pen. On d 14, 1 piglet was randomly selected from each pen for blood and tissue sampling. Dietary NCG supplementation enhanced (P < 0.05) growth rate and the efficiency of feed use in weaned Huanjiang mini-pig piglets. The NCG-supplemented diet increased (P < 0.05) mRNA expression levels of Slc6a19, Slc7a9, and Slc1a1 and the protein abundance of ASCT2, B(0)AT1, b(0,+)AT, y(+)LAT1, and EAAC1 in the jejunum. Furthermore, the contents of low density lipoprotein, ammonia, urea nitrogen, and AA as well as the activity of alkaline phosphatase in plasma were all altered (P < 0.05) by supplementation with NCG. These findings indicate that dietary supplementation with NCG may improve intestinal absorptive function in weaned piglets by increasing the expression of AA transporters in the intestine.

Soybean oligosaccharides alter colon short-chain fatty acid production and microbial population in vitro

This study was conducted to the determine fermentation characteristics of soybean oligosaccharides (SBOS) in an in vitro system. Digesta collected from the colon of Huanjiang mini-pigs was used as inoculums, and SBOS (0.2 g per 10 mL fermentation broth) was used as substrate during the in vitro fermentation. The inoculum or inoculum + glucose (0.2 g) was used as negative or positive control, respectively. The slurry was fermented in an anaerobic chamber and gas production (GP) recording was taken after 48 h of incubation by referring to the moving scale on the plunger of the glass syringes, and then GP parameters, pH value, NH(3)-N content, short chain fatty acid (SCFA) levels, and microbial community in the fermentation broth were determined. For gas production parameters, pH, and fermentation product determination after 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 28, 32, 36, 42, and 48 h of incubation, SBOS and glucose demonstrated similar responses compared to control including increase maximal gas production, decreased lag time, decreased pH, and accumulation of NH(3) and increased SCFA. The exception was rate of GP, which was higher (P < 0.05) for SBOS compared with glucose. Incubation with SBOS increased (P < 0.05) the microbial diversity and population of Bifidobacterium and Lactobacillus but decreased (P < 0.05) Escherichia and Streptococcus when compared with incubation with glucose. These findings suggested that the SBOS can improve the gut microbiota balance in colon and modulate its metabolism.

Variation of As concentration between soil types and rice genotypes and the selection of cultivars for reducing As in the diet

Human exposure to toxic heavy metals via the food chain is of increasing concern. In the present study, the effects of soil type and genotype on variation in arsenic (As) concentrations of different organs were investigated by using nine rice cultivars grown in two soils, with two levels of As contamination. There were significant genotypic differences (P<0.05) in As concentrations of all organs, and As concentrations of polished grain were significantly affected by genotype and soil type. The As concentration in polished grain was higher in red paddy soil under As treatment, with range from 0.24 to 1.03 mg kg(-1), and the As concentration of three cultivars exceeded the concentration of Chinese Food Hygiene Standard (0.7 mg kg(-1)). The As concentrations in stems, leaves and polished grain were all significantly and positively correlated. The As concentrations in polished grain were positively and significantly (P<0.01) correlated with As root-grain translocation factor. The results indicated that As concentration in grain was partially governed by As uptake and the transfer of As from root to grain. The grain As concentration of the nine cultivars was significantly correlated between the two soil types at different levels of As contamination. Some genotypes, such as japonica rice (e.g. Ning jing 1 and Nan jing 32) had consistently low grain As concentrations. The results suggest the possibility of breeding the As rice cultivars to produce grain for safe consumption from soils with slight and moderate levels of As.

[Esophageal voice training and quality of life in laryngectomees]

OBJECTIVE

To evaluate the extensive and degree of physical rehabilitation improvement of the quality of life in laryngectomees.

METHODS

Forty nine patients who underwent total laryngectomies were trained by esophageal voice rehabilitation successfully. The questionnaires of performance status scale for head and neck cancer patients (PSS-HN) and the functional assessment of head and neck cancer therapy (FACT-H&N) were answered by them before esophageal voice training and 3 months after successful vocal rehabilitation.

RESULTS

Total laryngectomy deteriorated the quality of life in laryngectomees. The mean scores of PSS-HN scale and FACT-H&N questionnaire were lower than the criteria scores after patients underwent total laryngectomy, the mean score were 131. 4,90.6 respectively, the difference was significant statistically (t =53. 673, P <0.001) , (t = 67.44, P <0.001). After successful esophageal speech training, the mean scores of the laryngectomees were improved both in PSS-HN scale and FACT-H&N which were 240.4 and 103.7 respectively, the difference was significant statistically (t = 18.209, P < 0.001) , (t = 21.389, P<0.001).

CONCLUSIONS

The quality of life in laryngectomees can be improved by physical rehabilitation and the esophageal voice training.

Measuring synthesis rates of nitrogen-containing polymers by using stable isotope tracers1,2

The major N-containing polymer compounds in the body include protein, RNA, and DNA. The endogenous gastrointestinal secretions as well as the portal-drained visceral and peripheral immune responses are basic physiological functions. Elevated endogenous secretions and immune activities, as affected by developmental stages, diets, and management factors, decrease the availability of dietary nutrients for peripheral muscle synthesis and deposition. Measurements of in vivo protein, RNA, and DNA synthesis rates associated with the viscera, peripheral immune cells, and skeletal muscles should, in principle, be the sensitive biochemical and cellular endpoints for studying factors affecting nonruminant nutrition, metabolism, and growth. The selection of stable isotope tracers for precursors, routes of tracer delivery, and mass spectrometric analyses of tracer enrichments are the major methodological considerations. To measure in vivo protein, RNA, and DNA synthesis rates, oral feeding with heavy water (2H2O), and continuous infusion of [U-13C]glucose and [15N]Gly intravenously for labeling the sugar moieties ribose and deoxyribose and de novo purine base synthesis have been established. Flooding doses of tracer Phe, for example, L-[ring-2H5]Phe, via the i.p. route are reliable and cost-effective for measuring in vivo protein synthesis rates, especially for the viscera in small nonruminants. Therefore, measurements of the major N-containing polymer synthesis rates in the viscera, the peripheral immune cells, and muscles through oral feeding with 2H2O and/or i.p. flooding doses of Phe tracers are the emerging tools for studying nonruminant nutrition, metabolism, and growth under research and field test conditions.

Effect of dietary oligochitosan supplementation on ileal digestibility of nutrients and performance in broilers

The effect of dietary chitosan oligosaccharides (COS) supplementation on ileal digestibilities of nutrients and performance in broilers was assessed by feeding graded levels (0, 50, 100, 150 mg/kg) of COS. Two thousand four hundred male commercial Avian broilers (1-d-old) were assigned randomly to 5 dietary treatment groups (60 birds per pen with 8 pens per treatment). Diet A was a typical corn- and soybean meal-based diet supplemented with 6 mg/kg of an antibiotic flavomycin (positive control). Diet B was the basal diet without any supplement. Diets C, D, and E were formulated by adding 50, 100, and 150 mg/kg of COS to the basal diet, respectively. On the morning of d 21 and 42, 64 birds (8 per pen with 8 pens per treatment) from the growth trial for each age group were killed by cervical dislocation for determination of the ileal digestibilities of nutrients. Dietary supplementation with COS and antibiotic enhanced (P < 0.05) the ileal digestibilities of DM, Ca, P, CP, and all amino acids (except for alanine in the 21-d-old birds or phenylalanine, glutamate, and glycine for the 42-d-old birds). Feed efficiency was improved (P < 0.05) in response to dietary supplementation of an antibiotic or COS (150 mg/kg for d 1 to 21, and 100 and 150 mg/kg for d 21 to 42). The results demonstrate for the first time to our knowledge that dietary COS supplementation was effective in increasing the ileal digestibilities of nutrients and feed efficiency in broilers. Our findings may explain a beneficial effect of COS on chicken growth performance.

[Evaluation of sentinel lymph node in squamous cell carcinoma of the head and neck]

OBJECTIVE

To assess the feasibility of sentinel lymph node (SLN) radiolocalization in stage in head and neck squamous cell carcinoma and to gain insight as to whether the sentinel lymph node could be prognostic of regional micrometastatic disease.

METHODS

A prospective trial was made on the application sentinel lymph node radiolocalization in 10 patients with NO squamous cell carcinoma of the head and neck region. For each patient a peritumoral submucosal injection of filtered technetium 99m prepared with dextran colloid (99mTc-DX) was performed immediately. After 30 minutes, focal areas of accumulation corresponding to sentinel lymph nodes (SLN) were marked on the skin surface. The SLN was localized by lymphoscintigraphy and intraoperatively through the intact skin by a hand-held gamma-probe. SLN was defined as the count of lymph node could be detected 4 times more than that of background. Complete neck dissections were performed, and SLNs were identified for later histological evaluation and comparison to the remaining lymphadenectomy specimen.

RESULTS

SLN radiolocalization accurately identified one or more SLNs in the ten cases. 3 of 10 cases revealed occult metastatic disease. Therefore the negative metastasis rate was 30% (3/10). The positive rate of SLN and nonsentinel lymph node (NSLN) were 22.7% (5/22) and 0.4% (1/247) respectively. Serial sectioning (SS) and immunohistochemical (IHC) on SLNs would reduce the false-negative rate of sentinel lymph node biopsy (SLNB). There was no instance in which SLN was negative for micrometastatic disease while being positive in a nonsentinel lymph node.

CONCLUSIONS

SLN evaluation in NO neck in squamous cell carcinoma of the head and neck is accurately feasible and seems to adequately predict the presence of occult metastasis. Although SLN radiolocalization in head and neck squamous cell carcinoma may potentially reduce the time, cost, and morbidity of regional lymph node management, more experience with technique is required before its role can be determined.

Evaluation of mobile nylon bag technique for determining apparent ileal digestibilities of protein and amino acids in growing pigs

The mobile nylon bag technique (MNBT) may offer a simple, rapid means for assessing ileal AA digestibility of pig feed ingredients. In the present study, the effects of washing bags recovered from digesta, the amount and fineness of feeds, and feed trypsin inhibitor activity on apparent ileal digestibilities (AID) of CP and AA were determined with the MNBT. Twenty-four ileorectal anastomosed pigs (Yorkshire x Chinese Black barrows, 30 kg initial BW), of which 12 were fitted with duodenal T-cannulas, were used. Not washing the bags recovered from ileal digesta resulted in a reduction (P < 0.05) in apparent ileal digestibilities of CP and AA determined by MNBT. Washing the bags for more than 4 min overestimated (P < 0.05) the apparent ileal digestibilities of CP and AA compared with those determined with the anastomosed pigs. Sample size and fineness of grinding also affected (P < 0.05) apparent ileal digestibilities of CP determined by MNBT. The apparent ileal digestibilities of CP determined by MNBT were reduced (P < 0.05) when sample size exceeded 0.75 g and when feed was ground through screens with a mesh size of more than 1.0 mm. The closest agreement between results obtained by MNBT and a conventional ileal digestibility assay occurred when 0.75 g of feed ground through a 1.0-mm mesh screen was used per bag and bags were washed for 2 min after retrieval from digesta. Further studies are warranted to investigate the use of the mobile nylon bag technique for predicting the ileal digestibilty of AA for feeds containing antinutritional factors.

Negative inotropic and chronotropic effects of oxytocin

We have previously shown that oxytocin receptors are present in the heart and that perfusion of isolated rat hearts with oxytocin results in decreased cardiac flow rate and bradycardia. The mechanisms involved in the negative inotropic and chronotropic effects of oxytocin were investigated in isolated dog right atria in the absence of central mechanisms. Perfusion of atria through the sinus node artery with 10(-6) mol/L oxytocin over 5 minutes (8 mL/min) significantly decreased both beating rate (-14.7+/-4.9% of basal levels, n=5, P<0.004) and force of contraction (-52.4+/-9.1% of basal levels, n=5, P<0.001). Co-perfusion with 10(-6) mol/L oxytocin receptor antagonist (n=3) completely inhibited the effects of oxytocin on frequency (P<0.04) and force of contraction (P<0.004), indicating receptor specificity. The effects of oxytocin were also totally inhibited by co-perfusion with 5x10(-8) mol/L tetrodotoxin (P<0.02) or 10(-6) mol/L atropine (P<0.03) but not by 10(-6) mol/L hexamethonium, which implies that these effects are neurally mediated, primarily by intrinsic parasympathetic postganglionic neurons. Co-perfusion with 10(-6) mol/L NO synthase inhibitor (L-NAME) significantly inhibited oxytocin effects on both beating rate (-1.85+/-1.27% versus -14.7+/-4.9% in oxytocin alone, P<0.05) and force of contraction (-24.9+/-4.4% versus -52.4+/-9.1% in oxytocin alone, n=4, P<0.04). The effect of oxytocin on contractility was further inhibited by L-NAME at 10(-4) mol/L (-8.1+/-1.8%, P<0.01). These studies imply that the negative inotropic and chronotropic effects of oxytocin are mediated by cardiac oxytocin receptors and that intrinsic cardiac cholinergic neurons and NO are involved in these actions.

Concentration-dependent effects of angiotensin II on sinus rate in canine isolated right atrial preparations

To investigate the concentration-response relationship of angiotensin II with respect to its chronotropic effects, the sinus rate was recorded from canine isolated right atrial preparations perfused through the sinus node artery. Nicotine (5 x 10(-5) M) injection induced an early, atropine-sensitive bradycardic response and a more delayed propranolol-sensitive tachycardic response, suggesting that the preparations contained both cholinergic and adrenergic neurons. The former response, but not the latter, was markedly reduced in preparations in which the right atrial ganglionated plexus was removed. Positive chronotropic responses were induced by angiotensin II over a wide range of concentrations (10(-12) - 5 x 10(-6) M), with a maximum increment of 29.9 +/- 9.6 beats/min. Responses to low concentrations (angiotensin II, 10(-11) M) were monophasic and were abolished by propranolol. In contrast, the responses to higher concentrations (angiotensin II, 10(-6) M) were not abolished by propranolol and were biphasic (early response, 29.9 +/- 12.1 beats/min; later response, 18.6 +/- 9.0 beats/min), the early response being blocked by losartan (AT1 antagonist) but not the later one, both being blocked by saralasin (nonselective angiotensin II antagonist). In conclusion, the data suggest that angiotensin II exerts its stimulant effects on the heart through receptors located either on cardiomyocytes or neurons, depending on the agonist concentration.

Nongenomic effect of triiodothyronine on cell surface beta-adrenoceptors in cultured embryonic cardiac myocytes

We studied the time course of cell surface beta-adrenoceptors (BAR) in cardiomyocytes in response to a single triiodothyronine (T3) (10(-8) M) stimulation. An early first increase of BAR density was observed within 2 hr (+ 10% versus control cells, P < 0.05), and a plateau was maintained for 17-20 hr. This effect was followed by a much greater, late increase of BAR density, starting around 22 hr and lasting until 48 hr post T3 addition (+40% versus control cells; p < 0.05). Since reverse T3 studied in the same conditions had no effect in this system, we concluded that this T3 effect was specific. We hypothesized that the early response might be nongenomic because the early effect of T3 was still observed in the presence of cycloheximide (2 x 10(-5) M) whereas the late increase was totally suppressed by the drug. The early response to T3 required intact microtubules, since colchicine (2 x 10(-5) M) was able to block the increase in the cell surface BAR number, but it did not involve a change in BAR distribution between external and internal sites, as the external to total BAR ratio remained stable. The measurement of the rate of BAR disappearance from the cell surface allowed us to hypothesize that T3 induced a modification of the turnover in cell surface BAR.

In vivo effects of amiodarone on cardiac beta-adrenoceptor density and heart rate require thyroid hormones

To assess if the anti-beta-adrenergic effect and the bradycardia induced by amiodarone were mediated by thyroid hormone, we investigated these effects of amiodarone in euthyroid and hypothyroid rats. We studied control rats, thyroidectomized rats, control rats treated with amiodarone (50 mg/kg for 8 days), and thyroidectomized rats treated with amiodarone. At the end of the treatment, free thyroid hormone levels (FT4 and FT3) were determined, and cardiac beta-receptor density (Bmax) and affinity (Kd) were assayed by using (-)-[125I]iodocyanopindolol as radioligand. Resting heart rate (rHR) was also assessed every day in control and thyroidectomized rats, before and after amiodarone. In hypothyroid rats, in which free thyroxine (FT4) was not detectable and free 3,5,3'-triiodothyronine (FT3) was only 16% that of euthyroid rats, Bmax (14.1 +/- 2.5 fmol/mg, n = 7) and rHR (259 +/- 9.7 beats/min, n = 6) were significantly lowered compared with euthyroid rats (Bmax:18.4 +/- 3.4 fmol/mg, n = 7; rHR:277 +/- 4.1 beats/min, n = 5). Amiodarone treatment decreased Bmax (13.6 +/- 2.9 fmol/mg, n = 8) and rHR (252 +/- 5.5 beats/min, n = 5) only in euthyroid rats and did not produce significant cardiac effects in hypothyroid rats. (Values are given as mean +/- SD.) We conclude that a minimum serum thyroid hormone concentration is a necessary condition for amiodarone to produce some of its cardiac effects. An antagonistic reaction to thyroid hormones at the cellular level can be postulated as a mechanism of the cardiac anti-beta-adrenergic action of amiodarone.

Amiodarone decreases cardiac beta-adrenoceptors through an antagonistic effect on 3,5,3' triiodothyronine

Because surprising similarities exist between the cardiac effects of amiodarone and those observed during hypothyroidism, we tested three different mechanisms of action in rats to determine whether amiodarone might act by inducing a tissular hypothyroidism: (a) a decrease in thyroid secretion, (b) an inhibiting effect on the conversion of thyroxine (T4) to 3,5,3' triiodothyronine (T3), and (c) a direct antagonistic effect on the cellular action of T3. Five groups of rats, treated orally for 7 or 13 days, were studied: I, control (0.5 ml saline for 7 or 13 days, n = 14); II, amiodarone (50 mg/kg for 7 days, n = 5); III, iopanoic acid (100 mg/kg for 13 days, n = 7); IV, control + T3 (0.5 ml saline for 13 days and 0.5 mg/kg T3 for the last 6 days, n = 5); V, amiodarone + T3 (amiodarone 50 mg/kg for 13 days and 0.5 mg/kg T3 for the last 6 days, n = 5). Cardiac beta-adrenoceptor density (CBARD) and heart rate (HR) were the two endpoint parameters investigated. Thyroid status was evaluated by serum thyrotropin (TSH), T4, T3, rT3 concentrations and liver type I 5'-deiodinase (5'D-I) activity. Amiodarone (group II) decreased CBARD (-22%, p less than 0.05) without altering thyroid secretion and T3 serum level, whereas 5'D-I was strongly inhibited (-90%, p less than 0.01). Iopanoic acid had no effect on CBARD and HR, but deeply inhibited 5'D-I.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo effects of macrolides on thyroid hormone serum levels and on hepatic type 1 5'-deiodinase in rat. A comparative study with amiodarone, phenobarbital and propranolol

Very often, an impact on the intracellular metabolism of iodothyronines and more precisely on microsomal deiodinases is evoked to explain thyroid hormone (TH) serum level alterations occurring with numerous drugs. Among them, three at least are also known to interfere with other hepatic microsomal enzymes, amiodarone (AMI), phenobarbital (PHE) and propranolol (PRO). Starting from this statement, we have examined the effects of 5 macrolides on TH serum level and on hepatic 5' type 1 deiodinase (5'DI) in vivo in rat. Rats were treated orally for eight days either with 200 mg/kg macrolides--erythromycine (ERY), troleandomycine (TRO), josamycine (JOS), midecamycine (MID) and spiramycine (SPI)--, or with AMI (45 mg/kg), PHE (50 mg/kg) or PRO (20 mg/kg), these 3 latter drugs for comparative purpose. Total T4, T3 and rT3 were determined by RIA. Hepatic 5'DI was evaluated by measuring released radioactive iodide from a reverse T3 monolabelled with 125I used substrate. Compared to control group, ERY and TRO decreased T4 (respectively by 28 and 16%) and from these two, only TRO decreased T3 (23%). With JOS, the only major modification was an increment of T3 (26%). AMI gave a typical alteration with a high T4 (130%), a low T3 (26%) and a high rT3 (376%). 5'DI was statistically inhibited by AMI (85%), JOS (49%), TRO (43%) and ERY (35%). The other drugs showed no significant effect. So, three macrolides have both altered TH serum level and 5'DI, findings which have never been reported before. The precise mechanism of this action remains unknown and the resulting effect, being far from the one observed with AMI, tends to demonstrate, for macrolides, an absence of correlation between the extent of 5'DI inhibition and TH serum profile. Besides, comparative analysis of the results observed with macrolides, AMI, PHE and PRO argues against any relationship between 5'DI and cytochrome-P450 monooxygenases.

Amiodarone: influence of the route of administration on thyroid status and cardiac beta-adrenoceptors in the rat

The influence of 2 different routes of amiodarone (AMIO) administration, oral gavage (OG) and subcutaneous injection (SC), on the density of cardiac beta-adrenoceptors (Bmax), hepatic type I 5' iodothyronine deiodinase (5' DI) and thyroid hormone serum concentrations was studied. Compared with respective control values, AMIO treatment (50 mg/kg per day, 7 days) via both OG and SC routes significantly lowered Bmax (OG: 14.6 +/- 1.92 vs 18.2 +/- 1.03 fmol/mg and SC: 16.6 +/- 2.34 vs 19.1 +/- 2.05 fmol/mg) and 5' DI activity (from 409 to 85 and 340 to 47 fmol I-/mg per min, respectively). The SC route induced a fall in thyroid secretion and a generalized hypothyroidism (decreased serum FT4 and FT3, inhibition of body weight gain. The OG route did not modify thyroid secretion. These results demonstrated that the effects on cardiac beta-receptor density in the SC group might be due to the generalized hypothyroidism and that AMIO produced its specific cardiac effects only after oral route medication, suggesting that the oral route is the best choice for studying AMIO cardiac effects on beta-receptor density.