Measurement of Electron-Neutrino Charged-Current Cross Sections on ^{127}I with the COHERENT NaIνE Detector

Using an 185-kg NaI[Tl] array, COHERENT has measured the inclusive electron-neutrino charged-current cross section on ^{127}I with pion decay-at-rest neutrinos produced by the Spallation Neutron Source at Oak Ridge National Laboratory. Iodine is one the heaviest targets for which low-energy (≤50  MeV) inelastic neutrino-nucleus processes have been measured, and this is the first measurement of its inclusive cross section. After a five-year detector exposure, COHERENT reports a flux-averaged cross section for electron neutrinos of 9.2_{-1.8}^{+2.1}×10^{-40}  cm^{2}. This corresponds to a value that is ∼41% lower than predicted using the MARLEY event generator with a measured Gamow-Teller strength distribution. In addition, the observed visible spectrum from charged-current scattering on ^{127}I has been measured between 10 and 55 MeV, and the exclusive zero-neutron and one-or-more-neutron emission cross sections are measured to be 5.2_{-3.1}^{+3.4}×10^{-40} and 2.2_{-0.5}^{+0.4}×10^{-40}  cm^{2}, respectively.

The ACE2 receptor accelerates but is not biochemically required for SARS-CoV-2 membrane fusion

The SARS-CoV-2 coronavirus infects human cells via the ACE2 receptor. Structural evidence suggests that ACE2 may not just serve as an attachment factor but also conformationally activate the SARS-CoV-2 spike protein for membrane fusion. Here, we test that hypothesis directly, using DNA-lipid tethering as a synthetic attachment factor in place of ACE2. We find that SARS-CoV-2 pseudovirus and virus-like particles are capable of membrane fusion without ACE2 if activated with an appropriate protease. Thus, ACE2 is not biochemically required for SARS-CoV-2 membrane fusion. However, addition of soluble ACE2 speeds up the fusion reaction. On a per-spike level, ACE2 appears to promote activation for fusion and then subsequent inactivation if an appropriate protease is not present. Kinetic analysis suggests at least two rate-limiting steps for SARS-CoV-2 membrane fusion, one of which is ACE2 dependent and one of which is not. Since ACE2 serves as a high-affinity attachment factor on human cells, the possibility to replace it with other factors implies a flatter fitness landscape for host adaptation by SARS-CoV-2 and future related coronaviruses.

Single-Virus Fusion Measurements Reveal Multiple Mechanistically Equivalent Pathways for SARS-CoV-2 Entry

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) binds to cell surface receptors and is activated for membrane fusion and cell entry via proteolytic cleavage. Phenomenological data have shown that SARS-CoV-2 can be activated for entry at either the cell surface or in endosomes, but the relative roles in different cell types and mechanisms of entry have been debated. Here, we used single-virus fusion experiments and exogenously controlled proteases to probe activation directly. We found that plasma membrane and an appropriate protease are sufficient to support SARS-CoV-2 pseudovirus fusion. Furthermore, fusion kinetics of SARS-CoV-2 pseudoviruses are indistinguishable no matter which of a broad range of proteases is used to activate the virus. This suggests that the fusion mechanism is insensitive to protease identity or even whether activation occurs before or after receptor binding. These data support a model for opportunistic fusion by SARS-CoV-2 in which the subcellular location of entry likely depends on the differential activity of airway, cellsurface, and endosomal proteases, but all support infection. Inhibition of any single host protease may thus reduce infection in some cells but may be less clinically robust. IMPORTANCE SARS-CoV-2 can use multiple pathways to infect cells, as demonstrated recently when new viral variants switched dominant infection pathways. Here, we used single-virus fusion experiments together with biochemical reconstitution to show that these multiple pathways coexist simultaneously and specifically that the virus can be activated by different proteases in different cellular compartments with mechanistically identical effects. The consequences of this are that the virus is evolutionarily plastic and that therapies targeting viral entry should address multiple pathways at once to achieve optimal clinical effects.

Experimental testing of a prototype cantilevered liquid-nitrogen-cooled silicon mirror

This report presents testing of a prototype cantilevered liquid-nitrogen-cooled silicon mirror. This mirror was designed to be the first mirror for the new soft X-ray beamlines to be built as part of the Advanced Light Source Upgrade. Test activities focused on fracture, heat transfer, modal response and distortion, and indicated that the mirror functions as intended.

Effect of arginine supplementation on the morphology and function of intestinal epithelia, and serum concentrations of amino acids in pigs exposed to heat stress

The exposure of pigs to heat stress (HS) appears to damage their intestinal epithelia, affecting the absorption of amino acids (AA). Arg is involved in the restoration of intestinal epithelial cells but HS reduces Arg intake. The effect of dietary supplementation with Arg on morphology of intestinal epithelia, AA transporter gene expression, and serum concentration (SC) of free AA in HS pigs were analyzed. Twenty pigs (25.3 ± 2.4 kg BW) were randomly assigned to two dietary treatments: control (0.81% Arg), wheat-soybean meal diet supplemented with L-Lys, L-Thr, DL-Met and L-Trp, and the experimental diet where 0.16% free L-Arg was supplemented to a similar control diet (+Arg). All pigs were individually housed and exposed to HS, fed at libitum with full access to water. The ambient temperature, recorded at 15-min intervals during the 21-d trial, ranged on average from 29.6 to 39.4 °C within the same day. Blood samples were collected on d18 at 1600 h (ambient temperature peak); serum was separated by centrifugation. At the end of the trial, five pigs per treatment were sacrificed to collect samples of mucosa scratched from each small intestine segment. The expression of AA transporters in intestinal mucosa and the SC of AA were analyzed. Villi height was higher (P < 0.01) in duodenum, jejunum, and ileum but the crypt depth did not differ between the control and the +Arg pigs. Supplementation of L-Arg increased the mRNA coding for the synthesis of the cationic AA transporter b 0,+ (P < 0.01) and the neutral AA transporter B 0 (P < 0.05) in duodenum by approximately five-folds and three-folds, respectively, but no effect on mRNA abundance was observed in jejunum and ileum. The supplementation of L-Arg increased serum Arg, His, Met, Thr, Trp, and urea (P < 0.05); tended to increase Val (P < 0.10), but did not affect Ile, Lys, Leu, and Phe. These results indicate that supplementing 0.16% L-Arg to the control diet may help to improve the function of the small intestine epithelium, by increasing the villi height, the abundance of AA transporters, and the SC of most indispensable AA in pigs exposed to HS conditions. However, the lack of effect of supplemental Arg on both Lys SC and weight gain of pigs suggests that increasing the Lys content in the +Arg diet might be needed to improve the performance of HS pigs.

Corticosteroids and tocilizumab reduce in-hospital mortality in severe COVID-19 pneumonia: a retrospective study in a Spanish hospital

Background

There is an urgent need to reduce mortality of COVID-19. We examined if corticosteroids and tocilizumab reduce risk for death in patients with severe pneumonia caused by SARS-CoV-2.

Methods

A retrospective cohort study was performed in a single university hospital. All adult patients admitted with confirmed severe COVID-19 pneumonia from 9 March to 9 April 2020 were included. Severe pneumonia was defined as multi-lobar or bilateral pneumonia and a ratio of oxygen saturation by pulse oximetry to the fraction of inspired oxygen (SpFi)<315. All patients received antiviral and antibiotic treatment. From March 26, patients also received immunomodulatory treatment with corticosteroids (methylprednisolone 250 mg/day for 3 days), or tocilizumab or both. In-hospital mortality in the entire cohort and in a 1:1 matched cohort sub-analysis was evaluated.

Results

255 patients were included, 118 received only antiviral and antibiotic treatment while 137, admitted after March 26, also received immunomodulators. In-hospital mortality of patients on immunomodulatory treatment was significantly lower than in those without [47/137(34.3%) vs. 69/118(58.5%), (p < .001)]. The risk of death was 0.44 (CI, 0.26–0.76) in patients receiving corticosteroids alone and 0.292 (CI, 0.18–0.47) in those treated with corticosteroids and tocilizumab. In the sub-analysis with 202 matched patients, the risk of death was 0.356 (CI 0.179–0.707) in patients receiving corticosteroids alone and 0.233 (0.124–0.436) in those treated with the combination.

Conclusions

Combined treatment with corticosteroids and tocilizumab reduced mortality with about 25% in patients with severe COVID-19 pneumonia. Corticosteroids alone also resulted in lower in-hospital mortality rate compared to patients receiving only antiviral and antibiotic treatment. Corticosteroids alone or combined with tocilizumab may be considered in patients with severe COVID-19 pneumonia.

Comparison of effectiveness and discontinuation of interferon-free therapy for hepatitis C in prison inmates and noninmates

Chronic hepatitis C treatment with direct acting antiviral (DAA) therapy during incarceration is an attractive option, due to its short duration and to the possibility of directly observed treatment or supervision. The aim of this study is to compare the effectiveness and rates of discontinuation of DAA treatment in prisoners and nonprisoners. We studied all patients treated in the 10 prisons of Catalonia and at 3 public hospitals in the Barcelona area between 1 January 2015 and 30 April 2016. We analysed sustained viral response (SVR) and rates of discontinuation through intention-to-treat and modified-intention-to-treat analyses, the latter excluding discontinuations due to release from prison. One hundred and eighty-eight inmates and 862 noninmates were included. Prisoners were significantly younger than nonprisoners, with higher proportions of men, drug users, HIV infection, genotypes 1a and 3 and more treatment with psychiatric drugs. Overall, 98.4% of patients completed treatment. The discontinuation rate was low, but higher in inmates (3.7% vs 1.2% noninmates; P = .003) and in community patients >65 years old (2.8% vs 1.2% in under 65 seconds; P = .008). Among the inmates, 7 (42.8%) discontinuations were due to release. SVR was 93.1% in inmates vs 96.5% in noninmates (P = .08) by intention-to-treat and 95.1% vs 96.5% (P = .37) by modified intention-to-treat. Virologic failure rates were similar (3.8% vs 3% in noninmates; P = .60). SVR, virologic failure and discontinuation rates were similar in inmates and noninmates. Currently, prisons are considered a priority for the implementation of DAA. Improved coordination between penitentiary and community health systems would help to ensure therapeutic continuity in released prisoners.

Increased dietary protein or free amino acids supply for heat stress pigs: effect on performance and carcass traits

Heat stress (HS) pigs reduce their voluntary feed intake (VFI) and ingestion of indispensable amino acids (AA). Increasing the dietary crude protein (CP) content may help to correct the reduced AA intake by HS pigs, but it may further increase their body heat load. Increasing the AA intake by adding free AA to the diet does not affect the heat load of HS pigs. Two 21-d experiments were conducted. In Exp. 1, 30 pigs (31.1 ± 1.2 kg initial body weight) were used to determine the performance depression because of HS. Treatments were: thermo neutral pigs fed a 22% CP control diet (TN-C); HS pigs fed the control diet (HS-C); HS pigs fed a 14% CP, AA supplemented diet (HS-AA). HS pigs had lower ADG and Lys utilization efficiency, and consumed 20 and 25% less Lys and Thr, respectively, than the TN-C pigs (P < 0.05). In Exp. 2 (comparative slaughter), 25 pigs (33.6 ± 0.65 kg initial body weight) were used to evaluate the effect of extra dietary AA either as protein-bound or free AA on the performance and carcass traits of HS pigs. Treatments were: control wheat-SBM-free Lys, Thr and Met diet (CON); diet with 30% more CP than CON (HSxP); diet added with free AA to contain at least 25% more of each AA than the recommended level (HSxAA). Ambient temperature (AT) ranged from 27.7 to 37.7°C, and body temperature (39.9 to 41.2°C) followed a similar daily pattern as the AT did. There was no dietary treatment effect on daily feed and NE intake (P > 0.10), but the Lys, Thr, and Met intake was higher in pigs fed the HSxP or HSxAA diets than in pigs fed the CON diet (P < 0.05). The daily weight gain (ADG) was not affected (P > 0.10) but G:F tended to be higher and the Lys utilization efficiency (ADG, g/g Lys intake) tended to be lower in HSxP pigs than in CON pigs (P < 0.10). The HSxAA pigs had higher ADG (P < 0.05), and tended to have higher weight of hot carcass and leg muscle, and the weight gain of hot carcass and leg muscle than the CON pigs (P < 0.10). The weight and daily weight gain of loin muscle was higher in the HSxAA than in the HSxP pigs (P < 0.05). Kidney weight and serum urea in HSxP pigs were higher than in CON and HSxAA pigs, but spleen weight was higher in HSxAA pigs than in CON and HSxP pigs (P < 0.05). These results confirm that HS reduces the VFI, and show that increased levels of AA either as free or protein-bound do not additionally reduce the VFI of HS pigs. These also show that extra free AA supply rather than protein-bound AA better ameliorate the reduced growth performance of HS pigs.

Reconsidering the 'Decline' of Dental Student Empathy within the Course in Latin America

INTRODUCTION

The controversy over the presence of empathic decline within the course in students of medicine, dentistry and health sciences in general, has not fully been studied. This controversy could be partially solved if massive studies of empathy levels are made in similar cultural, social and economic contexts.

MATERIAL AND METHODS

Empathy levels within the course were studied in eighteen dental schools from six countries in Latin America (2013). The mean of the empathy levels were used to study the behavior between first and fifth academic years. The values of empathy levels within the course were observed by applying the Jefferson Scale of Physician Empathy, the Spanish version. All these studies were cross-sectional. The value of means observed, were subjected to regression studies and further adjustment curves were obtained and the coefficient of determination were calculated.

RESULTS

Six different models of behavior were observed, which found that five of them suffer empathic decline within the course, but with different final results: in some the decline persists until the fifth academic year and in others, this decline 'recovers' persistently until the fifth academic year. The sixth model is characterized by a constant and persistent increase of levels of empathy within the course until the last academic year.

DISCUSSION

There are six different models for the behavior of means of levels of empathy within the course evaluated by a common methodology in eighteen dental schools from six countries of Latin America. These findings support the existence of variability of empathic response and a comprehensive approach is needed to find the causes that give rise to this variability.

CONCLUSION

In dental students of Latin America, there is variability in the behavior of the distribution in means between the academic years of the dentistry schools examined in this study.

First Dark Matter Search Results from the XENON1T Experiment

We report the first dark matter search results from XENON1T, a ∼2000-kg-target-mass dual-phase (liquid-gas) xenon time projection chamber in operation at the Laboratori Nazionali del Gran Sasso in Italy and the first ton-scale detector of this kind. The blinded search used 34.2 live days of data acquired between November 2016 and January 2017. Inside the (1042±12)-kg fiducial mass and in the [5,40]  keV_{nr} energy range of interest for weakly interacting massive particle (WIMP) dark matter searches, the electronic recoil background was (1.93±0.25)×10^{-4}  events/(kg×day×keV_{ee}), the lowest ever achieved in such a dark matter detector. A profile likelihood analysis shows that the data are consistent with the background-only hypothesis. We derive the most stringent exclusion limits on the spin-independent WIMP-nucleon interaction cross section for WIMP masses above 10  GeV/c^{2}, with a minimum of 7.7×10^{-47}  cm^{2} for 35-GeV/c^{2} WIMPs at 90% C.L.

Search for Electronic Recoil Event Rate Modulation with 4 Years of XENON100 Data

We report on a search for electronic recoil event rate modulation signatures in the XENON100 data accumulated over a period of 4 yr, from January 2010 to January 2014. A profile likelihood method, which incorporates the stability of the XENON100 detector and the known electronic recoil background model, is used to quantify the significance of periodicity in the time distribution of events. There is a weak modulation signature at a period of 431_{-14}^{+16} day in the low energy region of (2.0-5.8) keV in the single scatter event sample, with a global significance of 1.9σ; however, no other more significant modulation is observed. The significance of an annual modulation signature drops from 2.8σ, from a previous analysis of a subset of this data, to 1.8σ with all data combined. Single scatter events in the low energy region are thus used to exclude the DAMA/LIBRA annual modulation as being due to dark matter electron interactions via axial vector coupling at 5.7σ.

Effect of heat stress on the endogenous intestinal loss of amino acids in growing pigs

Heat stress (HS) increases the death of intestinal cells in pigs, which, in turn, may elevate the endogenous intestinal loss (EIL) of proteins and AA. An experiment was conducted to analyze the effect of HS on the AA composition of intestinal endogenous proteins and the EIL of AA in pigs. Eight pigs (25.2 ± 1.2 kg initial BW) were surgically implanted with T-type cannulas at the end of the small intestine. After surgery recovery, during the subsequent 7 d, all pigs were adapted to a protein- and AA-free diet and trained to consume the same amount of feed twice a day. All pigs were housed under thermoneutral (TN) conditions (22 ± 2°C) during this time. The following day, all pigs were still under TN conditions and ileal content was collected during 12 consecutive hours, at the end of which and for the following 8 d the pigs were exposed to natural HS conditions (31 to 37°C). Ileal content was collected again on d 2 (HS at d 2 [HSd2]) and 8 (HS at d 8 [HSd8]). Body temperature (BT) was measured in another group of 8 pigs every 15 min during the whole study. The average BT at HSd2 (39.6°C) was higher ( < 0.05) compared with both TN conditions (38.6°C) and HSd8 (38.8°C), but it did not differ between TN conditions and HSd8. The AA composition of endogenous intestinal protein was not affected by HS. The EIL of Arg and His were greater ( < 0.05) and the EIL of Thr and Phe tended to be greater ( ≤ 0.10) at HSd2 than in TN conditions; the EIL of Pro was greater ( = 0.01) at HSd8. The EIL of the remaining AA was not affected by HS. Although HS increased the EIL of Arg and His within the first 2 d, it appeared that normal EIL was shortly reestablished. These data show that acute HS does not affect the AA composition of intestinal endogenous proteins in growing pigs and that the EIL of AA may not be critical in growing pigs acclimated to high ambient temperature. Nevertheless, the increased EIL of Arg and Thr at HSd2 indicate that HS might affect the integrity of the intestinal epithelium of pigs during the first day of their exposure to high ambient temperature.

Effect of heat stress on the serum concentrations of free amino acids and some of their metabolites in growing pigs

Exposure to heat stress (HS) may affect the intestinal epithelia of pigs, resulting in impaired digestive and absorptive capacity. The serum concentration (SC) of free AA in pigs can be used as indicators of their availability. This study was conducted with 12 crossbred (Landrace × Hampshire × Duroc) pigs (29.0 ± 2.8 kg initial BW) distributed into 2 groups to analyze the SC of free AA and some AA metabolites in pigs exposed to HS conditions. The treatments were pigs housed under natural HS conditions in a room with no ambient temperature control (23.6 to 37.6°C, HS) and pigs housed at thermoneutral conditions (24 ± 2°C), feed restricted to a level similar to that of their HS counterparts. All pigs received a wheat-soybean meal diet. Blood samples were collected at both the absorptive (2.5 h after a meal) and postabsorptive (10.0 h after a meal) phase. At the absorptive phase, the SC of free Arg, Leu, Lys, Phe, Thr, and Trp were lower ( < 0.05) and the SC of His, Val, Ala, Pro, Ser, and Tyr tended to be lower ( < 0.10) in HS pigs. At the postabsorptive phase, the SC of free Arg, His, Met, Asn, Gln, and Tyr were higher ( < 0.05) but the SC of Ala was lower ( < 0.01) and the SC of Pro tended to be lower ( < 0.10) in HS pigs. The absorptive SC of carnosine, ornithine (Orn), and Tau were lower ( < 0.05) and of citrulline (Cit), cystathionine, and urea tended to be lower ( < 0.10) in HS pigs. The postabsorptive SC of 3-methyl-His, homo-Cys, OH-Lys, and OH-Pro increased ( = 0.05) and of Cit tended to increase ( = 0.10) but that of carnosine and sarcosine ( < 0.05) decreased in HS pigs. The results of this study show a marked and differential effect of HS on the SC of AA. These data indicate that HS negatively affects the digestive and absorptive capacity of pigs and that the metabolism of some AA is modified in pigs to counteract the negative effects of the HS.

Safe Reduction in CD4 Cell Count Monitoring in Stable, Virally Suppressed Patients With HIV Infection or HIV/Hepatitis C Virus Coinfection

BACKGROUND

It has been suggested that routine CD4 cell count monitoring in human immunodeficiency virus (HIV)-monoinfected patients with suppressed viral loads and CD4 cell counts >300 cell/μL could be reduced to annual. HIV/hepatitis C virus (HCV) coinfection is frequent, but evidence supporting similar reductions in CD4 cell count monitoring is lacking for this population. We determined whether CD4 cell count monitoring could be reduced in monoinfected and coinfected patients by estimating the probability of maintaining CD4 cell counts ≥200 cells/µL during continuous HIV suppression.

METHODS

The PISCIS Cohort study included data from 14 539 patients aged ≥16 years from 10 hospitals in Catalonia and 2 in the Balearic Islands (Spain) since January 1998. All patients who had at least one period of 6 months of continuous HIV suppression were included in this analysis. Cumulative probabilities with 95% confidence intervals were calculated using the Kaplan-Meier estimator stratified by the initial CD4 cell count at the period of continuous suppression initiation.

RESULTS

A total of 8695 patients were included. CD4 cell counts fell to <200 cells/µL in 7.4% patients, and the proportion was lower in patients with an initial count >350 cells/µL (1.8%) and higher in those with an initial count of 200-249 cells/µL (23.1%). CD4 cell counts fell to <200 cells/µL in 5.7% of monoinfected and 11.1% of coinfected patients. Of monoinfected patients with an initial CD4 cell count of 300-349 cells/µL, 95.6% maintained counts ≥200 cells/µL. In the coinfected group with the same initial count, this rate was lower, but 97.6% of coinfected patients with initial counts >350 cells/µL maintained counts ≥200 cells/µL.

CONCLUSIONS

From our data, it can be inferred that CD4 cell count monitoring can be safely performed annually in HIV-monoinfected patients with CD4 cell counts >300 cells/µL and HIV/HCV-coinfected patients with counts >350 cells/µL.

Dietary levels of protein and free amino acids affect pancreatic proteases activities, amino acids transporters expression and serum amino acid concentrations in starter pigs

The dietary contents of crude protein and free amino acids (AA) may affect the protein digestion and AA absorption in pigs. Trypsin and chymotrypsin activities, AA serum concentrations and expression of AA transporters in the small intestine of pigs fed a low protein, AA-supplemented (19.2%, LPAA) or a high protein (28.1%, HP), wheat-soybean meal diet were measured in two 14-d trials. The LPAA diet contained free L-Lys, L-Thr, DL-Met, L-Leu, L-Ile, L-Val, L-His, L-Trp and L-Phe. All pigs were fed the same amount of feed (890 and 800 g/d for trial 1 and 2 respectively). In trial 1, samples of mucosa (duodenum, jejunum and ileum) and digesta (duodenum and jejunum) were collected from 14 pigs (17.2 ± 0.4 kg); in trial 2, blood samples were collected from 12 pigs (12.7 ± 0.3 kg). The trypsin and chymotrypsin activities in both intestinal segments were higher in pigs fed the HP diet (p < 0.01). Trypsin activity was higher in jejunum than in duodenum regardless the dietary treatment (p < 0.05). Pigs fed the LPAA diet expressed more b^0,+ AT in duodenum, B⁰ AT1 in ileum (p < 0.05), and tended to express more y⁺ LAT1 in duodenum (p = 0.10). In pigs fed the LPAA diet, the expression of b^0,+ AT was higher in duodenum than in jejunum and ileum (p < 0.01), but no difference was observed in pigs fed the HP diet. Ileum had the lowest b^0,+ AT expression regardless the diet. The serum concentrations of Lys, Thr and Met were higher in LPAA pigs while serum Arg was higher in HP pigs (p < 0.05). Serum concentrations of AA appear to reflect the AA absorption. In conclusion, these data indicate that the dietary protein contents affect the extent of protein digestion and that supplemental free AA may influence the intestinal site of AA release and absorption, which may impact their availability for growth of young pigs.

Search for Event Rate Modulation in XENON100 Electronic Recoil Data

We have searched for periodic variations of the electronic recoil event rate in the (2-6) keV energy range recorded between February 2011 and March 2012 with the XENON100 detector, adding up to 224.6 live days in total. Following a detailed study to establish the stability of the detector and its background contributions during this run, we performed an unbinned profile likelihood analysis to identify any periodicity up to 500 days. We find a global significance of less than 1σ for all periods, suggesting no statistically significant modulation in the data. While the local significance for an annual modulation is 2.8σ, the analysis of a multiple-scatter control sample and the phase of the modulation disfavor a dark matter interpretation. The DAMA/LIBRA annual modulation interpreted as a dark matter signature with axial-vector coupling of weakly interacting massive particles to electrons is excluded at 4.8σ.

Expression of genes coding for selected amino acid transporters in small intestine, liver, and skeletal muscle of pigs fed excess branched-chain amino acids

Excess Leu reduces the availability of Ile and Val in pigs likely by reducing absorption of the latter amino acids (AA). Twenty-four crossbred pigs were used to evaluate the effect of excess Leu alone or with surplus Ile and Val on the expression of cationic (b(0),(+)AT and CAT1) and neutral (B(0)AT1) AA transporters in the small intestine, liver, and skeletal muscle. Dietary treatments included: 1) basal diet; 2) basal plus 0.43% L-Leu (excess Leu); 3) basal plus 0.43% Leu, 0.20% L-Ile, and 0.25% L-Val (excess Leu, Ile, and Val). The basal diet contained 0.90% standardized ileal digestible Lys, as well as crystalline L-Lys, L-Thr, DL-Met, L-Trp, L-Leu, L-Ile, L-His, and L-Val. Diets 2 and 3 contained 52% more Leu and diet 3 contained 42% more Ile and Val compared with the basal diet. Excess Leu or excess Leu, Ile, and Val reduced b(0),(+)AT expression in the jejunum (P < 0.05) but had no effect in the ileum and liver. Excess Leu increased CAT1 expression in the ileum but reduced expression in the liver (P < 0.05). Excess Leu, Ile, and Val increased (P < 0.05) B(0)AT1 expression in the jejunum and tended to increase (P = 0.10) expression in the ileum. In general, b(0),(+)AT expression was higher but CAT1 expression was lower in the jejunum than in the ileum; B0AT1 was similarly expressed in the jejunum and ileum. Excess Leu or any branched-chain AA affects AA transporter expression, which may affect the absorption and availability of AA for animal growth.

Low-protein amino acid-supplemented diets for growing pigs: effect on expression of amino acid transporters, serum concentration, performance, and carcass composition

Pigs fed protein-bound AA appear to have a higher abundance of AA transporters for their absorption in the jejunum compared with the duodenum. However, there is limited data about the effect of dietary free AA, readily available in the duodenum, on the duodenal abundance of AA transporters and its impact on pig performance. Forty-eight pigs (24.3 kg initial BW) distributed in 4 treatments were used to evaluate the effect of the CP level and form (free vs. protein bound) in which AA are added to diets on the expression of AA transporters in the 3 small intestine segments, serum concentration of AA, and performance. Dietary treatments based on wheat and soybean meal (SBM) were 1) low-CP (14%) diet supplemented with L-Lys, L-Thr, DL-Met, L-Leu, L-Ile, L-Val, L-His, L-Trp, and L-Phe (LPAA); 2) as in the LPAA but with added L-Gly as a N source (LPAA+N); 3) intermediate CP content (16%) supplemented with L-Lys HCl, L-Thr, and DL-Met (MPAA); and 4) high-CP (22%) diet (HP) without free AA. At the end of the experiment, 8 pigs from LPAA and HP were sacrificed to collect intestinal mucosa and blood samples and to dissect the carcasses. There were no differences in ADG, ADFI, G:F, and weights of carcass components and some visceral organs between treatments. Weights of the large intestine and kidney were higher in HP pigs (P < 0.01). Expression of b(0,+) in the duodenum was higher in pigs fed the LPAA compared with the HP diet (P= 0.036) but there was no difference in the jejunum and ileum. In the ileum, y+ L expression tended to be higher in pigs fed the LPAA diet (P = 0.098). Expression of b(0,+) in LPAA pigs did not differ between the duodenum and the jejunum, but in HP pigs, the expression of all AA transporters was higher in the jejunum than in the duodenum or ileum (P < 0.05). The serum concentration of Arg, His, Ile, Leu, Phe, and Val was higher but serum Lys and Met were lower in pigs fed the HP diet (P < 0.05). These results indicate that LPAA can substitute up to 8 percentage units of protein in HP wheat-SBM diets without affecting pig performance; nonessential N does not seem to be limiting in very low-protein wheat-SBM diets for growing pigs. Also, the inclusion of free AA in the diet appears to affect their serum concentration and the expression of the AA transporter b0,+ in the duodenum of pigs.

Gene expression, serum amino acid levels, and growth performance of pigs fed dietary leucine and lysine at different ratios

We examined 96 pigs (28.1 ± 0.83 kg) to analyze the effect of Leu:Lys ratios on expression of the cationic amino acid transporters b(0,+) and CAT-1 in the jejunum and liver as well as myosin expression in 2 muscles to estimate the optimum standardized ileal digestible (SID) Leu:Lys ratio for growth rate and efficiency. A wheat-and wheat bran-based diets were formulated to meet the requirements of SID amino acids other than Leu (0.70%) and Lys (0.80%). L-Leu was added to the basal diet in 5 SID Leu:Lys ratios (88, 100, 120, 140, and 160% in diets 1-5). Tissue samples were collected from 8 pigs with ratios of 88, 120, and 160%. Relative expression of b(0,+), CAT-1, and myosin was analyzed. b(0,+) expression in the jejunum was higher but lower in the liver of pigs with the 120% ratio compared to those with the 88 or 160% ratio; myosin expression in longissimus dorsi was also higher in pigs with the 120% ratio (P < 0.05). CAT-1 was lower in the jejunum and longissimus dorsi of pigs with 120 or 160% ratios than in pigs with 88%. Serum concentration of nearly all amino acids decreased with excess dietary Leu (P < 0.05). The SID Leu:Lys of 104 and 109% optimized average daily gain and feed conversion ratio, respectively. Thus, the dietary Leu:Lys ratio affects the expression of genes coding for amino acid transporters and myosin, the availability of Lys, and the growth rate and efficiency in pigs.

Effect of L-lysine on expression of selected genes, serum concentration of amino acids, muscle growth and performance of growing pigs

Lysine (Lys) is the first limiting amino acid (AA) in most feed formulations for pigs and most abundant, along with leucine, in muscle proteins. An experiment was conducted with 17 pigs (17.7 ± 0.05 kg initial BW) to identify a role of dietary Lys in the control of protein synthesis in pigs. Fourteen pigs were randomly assigned to one of the two wheat-based dietary treatments: Lys-deficient, 3.0 g/kg (DEF) and Lys-adequate, 10.8 g/kg (ADE). Samples from jejunum mucosa, liver, Longissumus and Semitendinosus muscles, and blood were collected. The other three pigs were sacrificed at the beginning of the trial to measure basal carcass composition. Weight gain, gain:feed ratio, Lys intake and loin eye area were greater in ADE than in DEF pigs (p < 0.01). Muscle-related carcass characteristics were better, and myosin heavy chain IIb expression (MyHC IIb) in Semitendinosus was higher in ADE than in DEF pigs. Expression of AA transporters CAT-1 was lower (p < 0.05), serum Lys was higher and serum Val was lower in pigs fed the ADE diet. The higher muscularity, MyHC IIb expression in Semitendinosus muscle and Lys serum of pigs fed the ADE diet suggest that Lys increases growth rate not only by functioning as protein construction unit but also as potential control of the protein synthesis process.

Effect of L-valine supplementation to a wheat-based diet with leucine excess on performance, gene expression, and serum concentration of amino acids

Excess Leu in the diet reduces the expression of the cationic AA transporter b(0,+), absorption of Lys and Arg, feed intake, and ADG of pigs. Because Val competes with Leu for absorption, surplus Val may correct some of these effects. An experiment was conducted to analyze the effect of surplus Val in a basal wheat (Triticum aestivum) diet fortified with free Lys, Thr, and Met and containing excess Leu and Ile on performance, expression of genes encoding b(0,+), and serum concentrations of AA. Sixteen pigs (30.3 ± 2.1 kg BW) were used. Treatments were wheat based with excess Leu and Ile (T1) and T1 plus 0.44% L-Val (T2). At the end of the 21-d study, 12 pigs were euthanized; jugular blood was collected to analyze serum AA and jejunal mucosa to measure expression of b(0,+). Surplus Val increased (P < 0.05) ADG and G:F and serum Val, Lys, and Arg but did not affect (P > 0.10) b(0,+) expression. Although analyzed Val content in the basal diet was lower than calculated, the increased serum Lys and improved pig performance may suggest that excess Leu limits Val availability and that surplus Val could correct some of the negative effects of excess Leu.

Growth performance, diet nutrient digestibility, and bone mineralization in weaned pigs fed pelleted diets containing thermostable phytase

Traditional supplemental dietary phytase loses activity during steam pelleting. The thermal tolerance and bioefficacy of a phytase product with a thermoprotective coating [coated phytase (C-phytase)] was compared in mash and pelleted diets to a traditional, uncoated phytase (U-phytase) added to a negative control (NC) diet, formulated with reduced dietary Ca and P, and compared with a corn-soybean meal based positive control (POC) diet. Growth performance, nutrient digestibility, and third metacarpal bone characteristics were response variables. Weaned pigs (n = 56; 8.20 ± 0.5 kg initial BW; 28 d of age) were individually housed and randomly allotted to 1 of 7 diets for 21 d. The diets were 1) POC mash, 2) NC mash, 3) NC pelleted at 90°C, 4) NC mash + 500 U/kg U-phytase, 5) NC mash + 500 U/kg C-phytase, 6) NC + 500 U/kg C-phytase pelleted at 80°C, and 7) NC + 500 U/kg C-phytase pelleted at 90°C. The POC and NC diets were formulated to be isoenergetic and isolysinic. The content of Ca and available P was 1.01 and 0.40% and 0.83 and 0.22% in the POC and NC diets, respectively. Pig BW and feed intake were measured on d 7, 14, and 21, and feces were collected for 2 d. On d 21, pigs were killed and ileal digesta and the third metacarpal bone collected. Pigs fed POC had greater (P < 0.05) ADG, G:F, P digestibility, and bone mineralization but lower (P < 0.01) energy digestibility than pigs fed NC. Pelleting the NC diet did not improve performance, nutrient digestibility, or P use. Adding the U-phytase to NC mash diet increased (P < 0.05) ADG, G:F, apparent ileal digestibility (AID) of CP and Ile, Leu, Phe, Thr, Val, and Ser, and apparent total tract digestibility (ATTD) of P compared with pigs fed NC. Pigs fed C-phytase in NC mash diets had increased (P < 0.05) G:F and an AID of CP and AA and ATTD of P compared with pigs fed NC but not different than pigs fed U-phytase NC mash diets. Pigs fed pelleted NC diet with C-phytase had a greater (P < 0.05) ATTD of P and energy than pigs fed mash NC diet with C-phytase but had similar growth performance, AID of CP and AA, and bone mineralization to pigs fed U-phytase. In conclusion, release and bioefficacy of phytase after pelleting was not affected by the thermal protective coating.

Effect of excess levels of lysine and leucine in wheat-based, amino acid-fortified diets on the mRNA expression of two selected cationic amino acid transporters in pigs

An experiment was conducted to evaluate the effect of excess levels of Leu and Lys on the expression of b(0,+) and CAT-1 mRNA in jejunum, liver and the muscles Longissimus dorsi (LDM) and Semitendinosus (STM). Twenty pigs with an average initial BW of 16.4 ± 1.7 kg were used in a Randomized Complete Block. Dietary treatments (T) were as follows: T1, basal diet; T2, basal plus 3.5 g l-Lys/kg diet; T3, basal plus 1.5 g l-Leu/kg diet; T4, basal plus 3.5 g l-Lys plus 1.5 g l-Leu/kg diet. Diets in T1 and T3 met 100% the requirement of Lys for pigs within the 10 to 20 kg body weight range; diets in T2 and T4 contained 35% excess of Lys. Also, diets in T1 and T2 supplied 104%, whereas diets in T3 and T4 supplied 116% the requirement of Leu. The expression of b(0,+) in jejunum was reduced (p = 0.002) because of the supplementation of l-Leu, but l-Lys supplementation had no effect (p = 0.738). In contrast, the expression of b(0,+) in STM (p = 0.012) and liver (p = 0.095) was reduced by the high level of Lys, but Leu had no effect (p > 0.100). CAT-1 expression in STM increased by high Lys (p = 0.023) and Leu (p = 0.007) levels. In liver, the expression of CAT-1 substantially increased (p = 0.001) because of Lys. In conclusion, excess levels of dietary Lys and Leu affect the expression of cationic amino acid transporters, and this effect varies depending on the studied tissue.

Effect of phytase and xylanase supplementation or particle size on nutrient digestibility of diets containing distillers dried grains with solubles cofermented from wheat and corn in ileal-cannulated grower pigs

Nutrient digestibility in distillers dried grains with solubles (DDGS) is limited by physical constraints such as particle size and by biochemical limitations such as phytate and fiber or nonstarch polysaccharides (NSP). To determine the separate effects of these limitations on nutrient digestibility, ground DDGS (383 µm) supplemented with phytase (0 or 250 units/kg of feed) and xylanase (0 or 4,000 units/kg of feed) was evaluated in a 2 × 2 factorial arrangement of treatments together with unground DDGS (517 µm) and an N-free diet in a 6 × 6 Latin square. Cofermented wheat and corn DDGS contained 8.6% moisture, 31.0% CP, 1.04% Lys, 8.0% ether extract, 2.0% starch, 40% NDF, and 0.85% P (as-is basis). Diets contained 43.7% DDGS as the sole source of AA; the digesta from pigs fed the N-free diet served to subtract basal endogenous AA losses and as control for energy digestibility. Six ileal-cannulated barrows (37.1 ± 0.8 kg of BW) were fed 6 diets at 2.8 × maintenance for DE in six 9-d periods. Feces and ileal digesta were collected for 2 d each. The apparent ileal digestibility (AID) of GE and apparent total tract digestibility (ATTD) of GE and NDF were 2.3, 0.5, and 5.1%-units greater (P < 0.05) for the ground than unground DDGS diet, respectively. Consequently, the ATTD of GE was 1.3%-units greater (P < 0.05) and the DE content was 0.06 Mcal/kg greater (P < 0.05) for ground than unground DDGS, respectively. Grinding of DDGS did not affect (P > 0.05) the ATTD of crude fiber, ADF, P, and Ca in diets. Grinding of DDGS increased (P < 0.05) the AID of most AA in diets including Lys, Met, and Thr by 6.9, 1.1, and 1.7%-units, respectively. Grinding of DDGS increased (P < 0.05) the SID of Lys by 6.2%-units and SID content of Lys and Thr by 0.06 and 0.02%-units, respectively. Phytase and xylanase did not interact (P > 0.05) to affect nutrient digestibility. Phytase increased (P < 0.001) the ATTD of P by 10.5%-units, but did not affect (P > 0.05) AA digestibility. Xylanase did not affect nutrient digestibility. In conclusion, particle size is an important physical characteristic affecting digestibility of energy and AA, but not P in DDGS. Phytate in DDGS limits digestibility of P, but not energy and AA. The substrate for xylanase in DDGS did not hinder energy and AA digestibility.

207 EFFECT OF LOCATION AND STAGE OF THE DOMINANT FOLLICLE ON OVULATION AND PREGNANCY RATES IN ALPACAS

Gestation in camelids occurs in the left horn regardless of whether ovulation has taken place in the left or right ovary, suggesting uterine embryo migration (Fernandez-Baca S et al. 1970 Biol. Reprod. 3, 243-251). On the other hand, we have previously documented (Ratto MH et al. 2003 Theriogenology 60, 1645-1656) that more than 90% of llamas with the presence of a follicle ≥6 to 7 mm in diameter, regardless of their stage of development, did accept the copula and ovulate after mating. However, it is unknown whether these oocytes are competent to achieving acceptable pregnancy rate. This study was designed to determine the effect of location of the preovulatory dominant follicle (right or left ovary) on ovulation and pregnancy rates and to evaluate the effect of stage of ovarian follicle development at mating (growing, maintenance, and regression) on ovulation rate and embryo survival in alpacas. In Experiment 1, nonlactating alpacas (4-6 years of age) weighing 55 to 75 kg were randomly assigned to 1 of 2 groups according to the location of the dominant follicle detected by ultrasonography: right ovary [right dominant follicle (RDF); n = 96] or left ovary [left dominant follicle (LDF); n = 108]. Ovulation and pregnancy diagnoses were assessed by ultrasonography on Days 2 (Day 0 = mating) and 30, respectively. Ovulation was defined as the sudden disappearance of a large follicle (≥6 mm) that was detected during the ultrasonographic examination 24 to 36 h after mating. Ovulation rates (96.5 and 96.3% for RDF and LDF, respectively) and pregnancy rates (60.2 and 56.7% for RDF and LDF, respectively) rates did not differ (P = 0.9) among groups. In Experiment 2, nonlactating alpacas (4-8 years of age) weighing 60 to 80 kg (n = 4116) were submitted to ultrasound-guided follicle ablation to synchronize follicular wave emergence and, after daily ultrasonography examination, were randomly assigned to the following groups according to the growth phase and diameter of the dominant follicle: early growing (G1; 5-6 mm, n = 27), mid-growing (G2; 7-12 mm, n = 30); static (G3; 7-12 mm, n = 430), or regressing (G4; 12-7 mm, n = 29). All alpacas were mated with a proven male, except 5 alpacas from G1 that rejected the sire. The ovarian response was determined by ultrasound examinations that were carried out on Day 2 (ovulation rate), Day 9 (CL size), and Day 35 (presence of embryonic vesicle or embryo). Ovulation was determined as described in Experiment 1. No differences were detected in ovulation rate among groups (95, 96, 100, and 96%, respectively; P = 0.8) or in CL size (10.3 ± 0.8; 11.7 ± 0.6; 11.1 ± 0.8; and 11.1 ± 0.9 mm, respectively; P = 0.6). Pregnancy rate was highest in G2 (65.5%), intermediate in G1 (52.4%) and G3 (53.3%), and lowest in G4 (42.9%; P < 0.05). Results suggest that location of the dominant follicle has no influence on ovulation and pregnancy rates and that although mating during the regressing phase of the dominant follicle has no effect on ovulation, pregnancy rate may be compromised. This study was supported by DID-UACH, Universidad Austral de Chile.