The estimation of protein equivalents of total nitrogen in Chinese CAPD patients: an explanatory study.

OBJECTIVE: The protein equivalent of total nitrogen appearance (PNA) formula, based on the urea nitrogen appearance (UNA), is popularly used by stable continuous ambulatory peritoneal dialysis (CAPD) patients to estimate dietary daily protein intake (DPI). However, we found that the estimated DPI was higher than that directly evaluated from the dietary records of most of our CAPD patients. Therefore, in the present study, we tried to determine possible bias in PNA estimation by UNA with a nitrogen balance study of our CAPD patients. METHODS: Thirty-one CAPD patients with stable clinical conditions were included. Their 3-day dietary records were reviewed by a dedicated dietitian to calculate their energy, protein, and nitrogen intake (NI). The nitrogen removal (NR) from urine and dialysate was measured by the Kjeldahl technique. Then, we calculated the proportion of urea nitrogen appearance (UNA) in total nitrogen appearance (TNA) and analyzed the possible factors that could affect this proportion. RESULTS: Among these patients, 17 males and 14 females, the mean age was 64.19 ± 12.42, and the dialysate drainage volume was 6700 (2540) ml/day. The percentage of UNA in TNA was 63.22 ± 6.66%. Compared with the other classic nitrogen balance studies in the CAPD population, the protein nitrogen and other nonurea nitrogen losses in this study were all lower. Based on these 31 nitrogen balance studies, we proposed a pair of new equations to estimate PNA by UNA. (1) PNA = 9.3 + 7.73 UNA; (2) PNA = PNPNA + TPL = 6.7 + 7.28 UNA + TPL. CONCLUSION: Our study suggested that the PNA formula generated from previous European studies overestimated DPI in our CAPD patients.

Feasibility of achieving different protein targets using a hypocaloric high-protein enteral formula in critically ill patients.

BACKGROUND AND AIMS: Combining energy and protein targets during the acute phase of critical illness is challenging. Energy should be provided progressively to reach targets while avoiding overfeeding and ensuring sufficient protein provision. This prospective observational study evaluated the feasibility of achieving protein targets guided by 24-h urinary nitrogen excretion while avoiding overfeeding when administering a high protein-to-energy ratio enteral nutrition (EN) formula. METHODS: Critically ill adult mechanically ventilated patients with an APACHE II score > 15, SOFA > 4 and without gastrointestinal dysfunction received EN with hypocaloric content for 7 days. Protein need was determined by 24-h urinary nitrogen excretion, up to 1.2 g/kg (Group A, N = 10) or up to 1.5 g/kg (Group B, N = 22). Variables assessed included nitrogen intake, excretion, balance; resting energy expenditure (REE); phase angle (PhA); gastrointestinal tolerance of EN. RESULTS: Demographic characteristics of groups were similar. Protein target was achieved using urinary nitrogen excretion measurements. Nitrogen balance worsened in Group A but improved in Group B. Daily protein and calorie intake and balance were significantly increased in Group B compared to Group A. REE was correlated to PhA measurements. Gastric tolerance of EN was good. CONCLUSIONS: Achieving the protein target using urinary nitrogen loss up to 1.5 g/kg/day was feasible in this hypercatabolic population. Reaching a higher protein and calorie target did not induce higher nitrogen excretion and was associated with improved nitrogen balance and a better energy intake without overfeeding. PhA appears to be related to REE and may reflect metabolism level, suggestive of a new phenotype for nutritional status. Trial registration 0795-18-RMC.

Analysis of Serum Metabolomics in Rats with Osteoarthritis by Mass Spectrometry.

Osteoarthritis is a common multifactorial chronic disease that occurs in articular cartilage, subchondral bone, and periarticular tissue. The pathogenesis of OA is still unclear. To investigate the differences in serum metabolites between OA and the control group, liquid chromatography/mass spectrometry (LC/MS)-based metabolomics was used. To reveal the pathogenesis of OA, 12 SD male rats were randomly divided into control and OA groups using collagenase to induce OA for modeling, and serum was collected 7 days after modeling for testing. The OA group was distinguished from the control group by principal component analysis and orthogonal partial least squares-discriminant analysis, and six biomarkers were finally identified. These biomarkers were metabolized through tryptophan metabolism, glutamate metabolism, nitrogen metabolism, spermidine metabolism, and fatty acid metabolism pathways. The study identified metabolites that may be altered in OA, suggesting a role in OA through relevant metabolic pathways. Metabolomics, as an important tool for studying disease mechanisms, provides useful information for studying the metabolic mechanisms of OA.

Biomarkers in critical care nutrition.

The goal of nutrition support is to provide the substrates required to match the bioenergetic needs of the patient and promote the net synthesis of macromolecules required for the preservation of lean mass, organ function, and immunity. Contemporary observational studies have exposed the pervasive undernutrition of critically ill patients and its association with adverse clinical outcomes. The intuitive hypothesis is that optimization of nutrition delivery should improve ICU clinical outcomes. It is therefore surprising that multiple large randomized controlled trials have failed to demonstrate the clinical benefit of restoring or maximizing nutrient intake. This may be in part due to the absence of biological markers that identify patients who are most likely to benefit from nutrition interventions and that monitor the effects of nutrition support. Here, we discuss the need for practical risk stratification tools in critical care nutrition, a proposed rationale for targeted biomarker development, and potential approaches that can be adopted for biomarker identification and validation in the field.

The Nitrogen Isotope Ratio Is a Biomarker of Yup'ik Traditional Food Intake and Reflects Dietary Seasonality in Segmental Hair Analyses.

BACKGROUND: The nitrogen isotope ratio (NIR) is a promising index of traditional food intake for an Alaska Native (Yup'ik) population, which can be measured in blood and hair. However, the NIR has not been calibrated to high-quality measures of Yup'ik traditional food intake. OBJECTIVES: Our primary objective was to examine associations between intakes of Yup'ik traditional food groups, including fish, marine mammals, birds, land mammals, berries, greens, and total traditional foods, and the NIR. In an exploratory analysis, we also examined whether NIR analyzed sequentially along hair could reflect dietary seasonality. METHODS: We recruited 68 participants from 2 Yup'ik communities in the Yukon Kuskokwim region of Southwest Alaska (49% female, aged 14-79 y). Participants completed 4 unscheduled 24-h food recalls over the period peak of RBC and hair synthesis preceding a specimen collection visit. The NIR was measured in RBCs ( n = 68), a proximal hair section (n = 58), and sequential segments of hair from individuals in the upper 2 quartiles of traditional food intake having hair >6 cm in length, plus 2 low subsistence participants for reference (n = 18). Diet-biomarker associations were assessed using Pearson's correlation and linear regression. RESULTS: Intakes of fish, marine mammals, berries, and greens were significantly associated with the NIR. The strongest dietary association was with total traditional food intake (R2 = 0.62), which indicated that each 1‰ increase in the RBC NIR corresponded to 8% of energy from traditional foods. Hair NIR appeared to fluctuate seasonally in some individuals, peaking in the summertime. CONCLUSIONS: Findings support the use of the RBC and hair NIR to assess total traditional food intake in a Yup'ik population. Analyses of sequential hair NIR provided evidence of seasonality in traditional food intake, although seasonal variations were modest relative to interindividual variation.

Tear glucose, creatinine, and urea nitrogen concentrations in cats with normal or increased plasma concentrations.

OBJECTIVE: The aim of the study was to determine the lacrimal fluid (LF) contents of glucose, urea nitrogen, and creatinine in cats. ANIMAL STUDIED: A total of 96 cats were included in the study. PROCEDURE: Venous blood and LF samples were collected. For LF sampling, three small polyurethane sponges were placed in the ventral fornix of both eyes. Both LF and plasma concentrations of glucose, urea nitrogen, and creatinine were quantitatively analyzed and compared. RESULT: Glucose (n = 40) and urea nitrogen concentrations (n = 42) measured in LF from both eyes highly correlated. While there was a very strong correlation (ρ = 0.97) between urea nitrogen concentrations in blood plasma and the corresponding tear levels (with the median LF urea nitrogen being 109% of that measured in plasma), the LF glucose concentrations were significantly lower than the corresponding plasma concentrations (with only 13% of the blood glucose concentration detected in the LF). The creatinine concentrations in tears were much lower than those in plasma, and LF creatinine was detectable in only 12/48 cats (25%). Hence, a comparison of the LF creatinine concentrations between both eyes or with the corresponding plasma creatinine concentration was not possible. CONCLUSION: Measurement of LF urea nitrogen concentrations in cats appears to be reliable and might have potential clinical utility. Measurement of LF glucose concentrations is less reliable but may still be useful in some cats. Creatinine is not reliably detected in the LF in cats. Further studies determining clinical utility of LF metabolites in cats and other companion animals are warranted.

Effect of surgical or immune castration on postprandial nutrient profiles in male pigs.

To avoid boar taint before slaughtering, late castration by immunisation against gonadotrophin releasing hormone or immunocastration has been developed. The current study aimed at determining whether differences in feed efficiency between castrated male (CM), immune castrated (IM) and entire male pigs (EM) can be explained by differences in nutrient plasma profiles after a meal. In this study, 24 male pigs (n = 8/type) were enrolled between 14 to 19 weeks of age. Entire and IM pigs ate less and were more feed efficient than CM pigs (p < 0.05). The postprandial plasma profiles of glucose, insulin, urea and amino acids (AA) were determined before (d -6), just after (d 8) and well after (d 16) the decrease in testicular hormones in IM pigs. For each test day, pigs were fasted overnight and subsequently fed a small meal (400 g). On d -6, postprandial profiles of plasma glucose of IM pigs did not differ from the two other types of pigs. On d 8, EM pigs had a greater average plasma glucose concentration than IM and CM pigs (p < 0.05) but the profiles did not differ. On d 16, the differences between profiles of glucose suggest a lower clearance of glucose in EM compared with IM and CM pigs. Plasma insulin did not significantly differ between the three types. Plasma urea profiles did not differ between CM, EM and IC pigs on d -6 whereas CM pigs showed higher plasma urea concentrations than EM and IM thereafter (p < 0.01). Among AA, Lys plasma concentrations were greater in CM than in EM and IM pigs on d -6, d 8 and d 16 (p < 0.05), whereas on d 16 plasma Hypro concentrations were lower in CM than in EM and IM pigs (p < 0.05). The finding that plasma glucose profiles were modified by immunocastration much faster and earlier than urea and AA profiles, suggest that the decrease in testicular hormones impacted energy metabolism more rapidly than protein metabolism.

Pharmacokinetics of glycerol phenylbutyrate in pediatric patients 2 months to 2 years of age with urea cycle disorders.

INTRODUCTION: Glycerol phenylbutyrate (GPB) is approved in the US and EU for the chronic management of patients ≥2 months of age with urea cycle disorders (UCDs) who cannot be managed by dietary protein restriction and/or amino acid supplementation alone. GPB is a pre-prodrug, hydrolyzed by lipases to phenylbutyric acid (PBA) that upon absorption is beta-oxidized to the active nitrogen scavenger phenylacetic acid (PAA), which is conjugated to glutamine (PAGN) and excreted as urinary PAGN (UPAGN). Pharmacokinetics (PK) of GPB were examined to see if hydrolysis is impaired in very young patients who may lack lipase activity. METHODS: Patients 2 months to <2 years of age with UCDs from two open label studies (n = 17, median age 10 months) predominantly on stable doses of nitrogen scavengers (n = 14) were switched to GPB. Primary assessments included traditional plasma PK analyses of PBA, PAA, and PAGN, using noncompartmental methods with WinNonlin™. UPAGN was collected periodically throughout the study up to 12 months. RESULTS: PBA, PAA and PAGN rapidly appeared in plasma after GPB dosing, demonstrating evidence of GPB cleavage with subsequent PBA absorption. Median concentrations of PBA, PAA and PAGN did not increase over time and were similar to or lower than the values observed in older UCD patients. The median PAA/PAGN ratio was well below one over time, demonstrating that conjugation of PAA with glutamine to form PAGN did not reach saturation. Covariate analyses indicated that age did not influence the PK parameters, with body surface area (BSA) being the most significant covariate, reinforcing current BSA based dosing recommendations as seen in older patients. CONCLUSION: These observations demonstrate that UCD patients aged 2 months to <2 years have sufficient lipase activity to adequately convert the pre-prodrug GPB to PBA. PBA is then converted to its active moiety (PAA) providing successful nitrogen scavenging even in very young children.

Estimating Time-averaged Serum Urea Nitrogen Concentration during Various Urine Collection Periods: A Prediction Equation for Thrice Weekly and Biweekly Dialysis Schedules.

Residual kidney urea clearance in dialysis patients typically is calculated as the per minute excretion of urea nitrogen, obtained during the 24-48 hour collection period that usually ends just prior to a dialysis session, divided by the time-averaged serum water urea nitrogen concentration during the collection period. This concentration is difficult to estimate unless a formal kinetic modeling program is being used. We used a urea kinetic modeling program to derive an equation to estimate the time-averaged serum water concentration during urine collection periods of various lengths collected during various interdialytic intervals, for 3/week or 2/week dialysis schedules. The equation to predict time-averaged serum water urea nitrogen concentration during the collection period was a function of the ratio of the duration of the predialysis collection period to the duration of the interdialytic interval during which the collection was accomplished, as well as the urea reduction ratio and predialysis serum urea nitrogen concentration of the dialysis session immediately following the end of the collection period.

Dehydroepiandrosterone Supplementation Combined with Whole-Body Vibration Training Affects Testosterone Level and Body Composition in Mice.

Dehydroepiandrosterone (DHEA), the most abundant sex steroid, is primarily secreted by the adrenal gland and a precursor hormone used by athletes for performance enhancement. Whole-body vibration (WBV) is a well-known light-resistance exercise by automatic adaptations to rapid and repeated oscillations from a vibrating platform, which is also a simple and convenient exercise for older adults. However, the potential effects of DHEA supplementation combined with WBV training on to body composition, exercise performance, and hormone regulation are currently unclear. The objective of the study is to investigate the effects of DHEA supplementation combined with WBV training on body composition, exercise performance, and physical fatigue-related biochemical responses and testosterone content in young-adult C57BL/6 mice. In this study, male C57BL/6 mice were divided into four groups (n = 8 per group) for 6-weeks treatment: sedentary controls with vehicle (SC), DHEA supplementation (DHEA, 10.2 mg/kg), WBV training (WBV; 5.6 Hz, 2 mm, 0.13 g), and WBV training with DHEA supplementation (WBV+DHEA; WBV: 5.6 Hz, 2 mm, 0.13 g and DHEA: 10.2 mg/kg). Exercise performance was evaluated by forelimb grip strength and exhaustive swimming time, as well as changes in body composition and anti-fatigue levels of serum lactate, ammonia, glucose, creatine kinase (CK), and blood urea nitrogen (BUN) after a 15-min swimming exercise. In addition, the biochemical parameters and the testosterone content were measured at the end of the experiment. Six-week DHEA supplementation alone significantly increased mice body weight (BW), muscle weight, testosterone level, and glycogen contents (liver and muscle) when compared with SC group. DHEA supplementation alone had no negative impact on all tissue and biochemical profiles, but could not improve exercise performance. However, WBV+DHEA supplementation also significantly decreased BW, testosterone level and glycogen content of liver, as well as serum lactate and ammonia levels after the 15-min swimming exercise when compared with DHEA supplementation alone. Although DHEA supplementation alone had no beneficial effect in the exercise performance of mice, the BW, testosterone level and glycogen content significantly increased. On the other hand, WBV training combined with DHEA decreased the BW gain, testosterone level and glycogen content caused by DHEA supplementation. Therefore, WBV training could inhibit DHEA supplementation to synthesis the testosterone level or may decrease the DHEA supplement absorptive capacity in young-adult mice.

Dual anti-neutrophil cytoplasmic antibody-related pauci-immune crescentic glomerulonephritis in a patient with Sjögren's syndrome.

Sjögren's syndrome is an autoimmune disease that primarily affects exocrine glands. Renal involvement of Sjögren's syndrome may lead to tubulointerstitial disease, whereas secondary glomerulopathies such as anti-neutrophil cytoplasmic antibody (ANCA)-related pauci-immune crescentic glomerulonephritis are rarely observed. In addition, crescent glomerulonephritis that is simultaneously positive for both myeloperoxidase (MPO)-ANCA and proteinase 3 (PR3)-ANCA has never been reported in Sjögren's syndrome. Here, we report a case of pauci-immune crescentic glomerulonephritis exhibiting positivity for both MPO- and PR3-ANCAs in a patient with primary Sjögren's syndrome. A 71-year-old female was hospitalized for cough, blood-tinged sputum, and dyspnea two weeks after diagnosis with Sjögren's syndrome. On admission, serum anti-nuclear antibody, anti-Ro/SS-A antibody, MPO-ANCA, and PR3-ANCA were all positive, and serum blood urea nitrogen and creatinine (Cr) levels were 42.7 and 2.9 mg/dL, respectively. On the seventh day of hospitalization, the patient's serum Cr level was 5.7 mg/dL, indicating rapidly progressive glomerulonephritis. Renal biopsy resulted in the diagnosis of ANCA-related pauci-immune crescentic glomerulonephritis, for which intravenous methylprednisolone (7 mg/kg/day) was administered for three consecutive days, followed by combination therapy with oral prednisolone (1 mg/kg/day) and intravenous cyclophosphamide (500 mg/m(2)). The patient was positive in the Schirmer's I test, and a salivary gland biopsy showed sialadenitis with lympho-plasmacytic infiltrations. On day 28 of hospitalization, the patient was discharged after amelioration of respiratory symptoms and azotemia. At 6 months after discharge, the patient continued to receive appropriate daily medications and was negative for both MPO- and PR3-ANCAs, with a slight elevation in serum Cr levels.

Short-chain fatty acids and acidic pH upregulate UT-B, GPR41, and GPR4 in rumen epithelial cells of goats.

Currently, the mechanism(s) responsible for the regulation of urea transporter B (UT-B) expression levels in the epithelium of the rumen remain unclear. We hypothesized that rumen fermentation products affect ruminal UT-B expression. Therefore, the effects of short-chain fatty acids (SCFA), pH, ammonia, and urea on mRNA and protein levels of UT-B were assayed in primary rumen epithelial cell cultures and in rumen epithelium obtained from intact goats. In vitro, SCFA and acidic pH were found to synergetically stimulate both mRNA and protein expression of UT-B, whereas NH4Cl decreased mRNA and protein levels of UT-B at pH 6.8. Treatment with urea increased both levels at pH 7.4. When goats received a diet rich in nitrogen (N) and nonfiber carbohydrates (NFC), their rumen epithelium had higher levels of UT-B, and the rumen contained higher concentrations of SCFA and NH3-N with a lower pH. An increase in plasma urea-N concentration was also observed compared with the plasma of the goats that received a diet low in N and NFC. In a second feeding trial, goats that received a NFC-rich, but isonitrogenous, diet had higher mRNA and protein levels of UT-B, and higher levels of G protein-coupled receptor (GPR) 41 and GPR4, in their rumen epithelium. The ruminal concentrations of SCFA and NH3-N also increased, while a lower pH was detected. In contrast, the serum urea-N concentrations remained unchanged. These data indicate that ruminal SCFA and pH are key factors, via GPR4 and GPR41, in the dietary regulation of UT-B expression, and they have priority over changes in plasma urea.

High True Ileal Digestibility but Not Postprandial Utilization of Nitrogen from Bovine Meat Protein in Humans Is Moderately Decreased by High-Temperature, Long-Duration Cooking.

BACKGROUND: Meat protein digestibility can be impaired because of indigestible protein aggregates that form during cooking. When the aggregates are subsequently fermented by the microbiota, they can generate potentially harmful compounds for the colonic mucosa. OBJECTIVE: This study evaluated the quantity of bovine meat protein escaping digestion in the human small intestine and the metabolic fate of exogenous nitrogen, depending on cooking processes. METHODS: Sixteen volunteers (5 women and 11 men; aged 28 ± 8 y) were equipped with a double lumen intestinal tube positioned at the ileal level. They received a test meal exclusively composed of 120 g of intrinsically (15)N-labeled bovine meat, cooked either at 55°C for 5 min (n = 8) or at 90°C for 30 min (n = 8). Ileal effluents and blood and urine samples were collected over an 8-h period after the meal ingestion, and (15)N enrichments were measured to assess the digestibility of meat proteins and the transfer of dietary nitrogen into the metabolic pools. RESULTS: Proteins tended to be less digestible for the meat cooked at 90°C for 30 min than at 55°C for 5 min (90.1% ± 2.1% vs. 94.1% ± 0.7% of ingested N; P = 0.08). However, the particle number and size in ileal digesta did not differ between groups. The appearance of variable amounts of intact fibers was observed by microscopy. The kinetics of (15)N appearance in plasma proteins, amino acids, and urea were similar between groups. The amount of exogenous nitrogen lost through deamination did not differ between groups (21.2% ± 0.8% of ingested N). CONCLUSIONS: Cooking bovine meat at a high temperature for a long time can moderately decrease protein digestibility compared with cooking at a lower temperature for a short time and does not affect postprandial exogenous protein metabolism in young adults. The study was registered at www.clinicaltrials.gov as NCT01685307.

Risk Stratification of Acute Kidney Injury Using the Blood Urea Nitrogen/Creatinine Ratio in Patients With Acute Decompensated Heart Failure.

BACKGROUND: Risk stratification of acute kidney injury (AKI) is important for acute decompensated heart failure (ADHF). The aim of this study was to determine whether clinical markers, such as the blood urea nitrogen/creatinine ratio (BUN/Cr) or BUN or creatinine values alone, stratify the risk of AKI for mortality. METHODS AND RESULTS: In all, 371 consecutive ADHF patients were enrolled in the study. AKI was defined as serum creatinine ≥0.3 mg/dl or a 1.5-fold increase in serum creatinine levels within 48 h. During ADHF therapy, AKI occurred in 99 patients; 55 patients died during the 12-month follow-up period. Grouping patients according to AKI and a median BUN/Cr at admission of 22.1 (non-AKI+low BUN/Cr, non-AKI+high BUN/Cr, AKI+low BUN/Cr, and AKI+high BUN/Cr groups) revealed higher mortality in the AKI+high BUN/Cr group (log-rank test, P<0.001). Cox's proportional hazard analysis revealed an association between AKI+high BUN/Cr and mortality, whereas the association with AKI+low BUN/Cr did not reach statistical significance. When patients were grouped according to AKI and median BUN or creatinine values at admission, AKI was associated with mortality, regardless of BUN or creatinine. CONCLUSIONS: The combination of AKI and elevated BUN/Cr, but not BUN or creatinine individually, is linked with an increased risk of mortality in ADHF patients, suggesting that the BUN/Cr is useful for risk stratification of AKI.

Disturbed release of cholecystokinin in pregnant women with hyperemesis gravidarum.

AIMS: We aimed to investigate cholecystokinin (CCK) release in pregnant women with and without hyperemesis gravidarum (HG). MATERIAL AND METHODS: In this case-control study including 40 pregnant women with HG and 40 women with healthy uncomplicated pregnancies, serum CCK levels in addition to hematological, biochemical and hormonal parameters were investigated. RESULTS: Serum CCK values were found to be significantly lower in pregnant women with HG (P < 0.001). Additionally, while serum blood urea nitrogen and free thyroxine levels were significantly higher, sodium, potassium, and thyroid stimulating hormone levels were significantly lower in women with HG than in control women. No correlation was detected between CCK and other parameters like ketonuria and thyroid function tests. CONCLUSIONS: CCK release has been found to be halved in pregnant women with HG, which supports the hypothesis that gastrointestinal motility is increased in pregnant women with HG. A causal effect remains to be confirmed.

Plasma nitrogen isotopic fractionation and feed efficiency in growing beef heifers.

Fractionation of N isotopes occurs in many metabolic reactions which causes tissue proteins to become enriched in ¹5N while urea (urine) is depleted in ¹5N relative to the diet. We investigated ¹5N enrichment of whole plasma and its relationship with feed conversion efficiency (FCE) in growing beef heifers (n 84) offered 2 kg/d of concentrates with grass silage ad libitum. Heifers were on average 299 (SD 48·3) d old and weighed 311 (SD 48·8) kg. Plasma was obtained on day 79 (n 84) of the experiment and from a subset of animals (n 20) on four occasions between days 16 and 79. Silage DM intake (DMI) averaged 4·1 (SD 0·74) kg/d and concentrate DMI was 1·72 kg/d. Mean mid-test live weight was 333 (SD 47·6) kg, daily gain was 0·53 (SD 0·183) kg, FCE (g live-weight gain/g DMI) was 0·09 (SD 0·028) and residual feed intake (RFI) was 0 (SD 0·428). N isotopic fractionation (Δ¹5N; plasma δ¹5N - diet δ¹5N) averaged 3·58 ‰ on day 79 (n 84) and 3·90 ‰ for the subset of heifers. There was no relationship between Δ¹5N and RFI. Plasma δ¹5N and Δ¹5N were related to both FCE (negative) and animal weight (positive) for the whole population, and repeatable for the subset of animals over four time points. These relationships of Δ¹5N with FCE and animal weight are consistent with the anticipated negative relationship with N-use efficiency. There is potential to use Δ¹5N to provide rapid, low-cost estimates of FCE in cattle.

Treatment of micro air bubbles in rat adipose tissue at 25 kPa altitude exposures with perfluorocarbon emulsions and nitric oxide.

INTRODUCTION: Perfluorocarbon emulsions (PFC) and nitric oxide (NO) releasing agents have on experimental basis demonstrated therapeutic properties in treating and preventing the formation of venous gas embolism as well as increased survival rate during decompression sickness from diving. The effect is ascribed to an increased solubility and transport capacity of respiratory gases in the PFC emulsion and possibly enhanced nitrogen washout through NO-increased blood flow rate and/or the removal of endothelial micro bubble nuclei precursors. Previous reports have shown that metabolic gases (i.e., oxygen in particular) and water vapor contribute to bubble growth and stabilization during altitude exposures. Accordingly, we hypothesize that the administration of PFC and NO donors upon hypobaric pressure exposures either (1) enhance the bubble disappearance rate through faster desaturation of nitrogen, or in contrast (2) promote bubble growth and stabilization through an increased oxygen supply. METHODS: In anesthetized rats, micro air bubbles (containing 79% nitrogen) of 4-500 nl were injected into exposed abdominal adipose tissue. Rats were decompressed in 36 min to 25 kPa (~10,376 m above sea level) and bubbles studied for 210 min during continued oxygen breathing (FIO2 = 1). Rats were administered PFC, NO, or combined PFC and NO. RESULTS: In all groups, most bubbles grew transiently, followed by a stabilization phase. There were no differences in the overall bubble growth or decay between groups or when compared with previous data during oxygen breathing alone at 25 kPa. CONCLUSION: During extreme altitude exposures, the contribution of metabolic gases to bubble growth compromises the therapeutic effects of PFC and NO, but PFC and NO do not induce additional bubble growth.

Nitrogen partitioning and milk production of dairy cows grazing simple and diverse pastures.

Research was conducted to examine the effects of a diverse pasture mix on dry matter intake, milk yield, and N partitioning of lactating dairy cows. A pasture containing only ryegrass and white clover (RG), or high-sugar ryegrass and white clover (HS), was compared with a diverse pasture mix (HSD) including chicory, plantain, lotus, high-sugar ryegrass, and white clover. The experiment was conducted over a 10-d period using 3 groups of 12 cows in late lactation. No difference was observed in dry matter (14.3 kg of dry matter/cow per day) or N (583 g of N/cow per day) intake between treatments. The cows grazing the HSD pasture had an increased milk yield (16.9 kg/d) compared with those grazing the simple RG and HS pastures (15.2 and 14.7 kg/d, respectively). However, no differences were observed in milk solids yield for the 3 treatments. A tendency toward greater milk protein yields in the HSD group resulted in improved N use efficiency for milk of 20.4% from the cows fed HSD, compared with 17.8 and 16.7% from cows in the RG and HS treatments, respectively. Urinary N excretion was lower from the cows fed HSD, at 353.8 g/d, compared with 438.3 and 426.6 g/d for cows fed RG and HS, respectively. These results suggest that the use of pastures containing chicory, lotus, and plantain can contribute to the goal of reducing N losses from cows in late lactation.

Induced metabolic disturbance and growth depression in rabbits infected with Eimeria coecicola.

Eimeria coecicola causes intestinal coccidiosis in rabbits and, thereby, enormous economic losses in rabbit farms. This study aimed to investigate the effect of intestinal coccidial infection, E. coecicola on metabolic status and growth of rabbits. Animals were allocated into two groups with eight rabbits each; one group was orally inoculated with saline and served as control while the other group was orally inoculated with 5 × 10(4) sporulated oocysts. On day 7 postinfection, fecal expulsion of E. coecicola oocysts is maximal (1.2 × 10(6) oocyst/g feces) and rabbits have lost approximately 23% of their weight. Infection induced a severe depletion in plasma growth hormone level. In addition, the energy metabolic status was significantly (P ≤ 0.05) altered by the infection as, both blood glucose and total lipid levels were significantly elevated with mutual depletion in carbohydrate stores in liver sections. Also, the thyroid-stimulating hormone and cortisol concentrations were raised as a consequence of the infection. Moreover, protein status was affected by the infection as both liver and plasma total proteins were significantly decreased with concurrent disturbance in the blood protein electrophoretic pattern and duplication of blood urea nitrogen concentration. Finally, the infection induced plasma electrolyte imbalance as indicated by a significant decrease in sodium, potassium, calcium, phosphorus, ferrous, and selenium ions. Our data suggested that the intestinal coccidial infection of rabbits with E. coecicola has serious effects on rabbit growth and metabolism and could disrupt endocrine and electrolyte homeostasis.