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Hyperinsulinemia concurrent with hypoglycemia is one of a myriad of physiological changes typically experienced by lactating dairy cows exposed to heat stress, the consequences of which are not yet well defined or understood. Therefore, the objective of this experiment was to separate the production-related effects of hyperinsulinemia with hypoglycemia from those of a hyperthermic environment. Multiparous lactating Holstein cows (n = 23; 58 ± 4 d in milk, 3.1 ± 0.3 lactations) were housed in temperature-controlled rooms and all were subjected to 4 experimental periods as follows: (1) thermoneutral (TN; temperature-humidity index of 65.1 ± 0.2; d 1-5), (2) TN + hyperinsulinemic-hypoglycemic clamp (HHC; insulin infused at 0.3 µg/kg of BW per h, glucose infused to maintain 90 ± 10% of baseline blood glucose for 96 h; d 6-10), (3) heat stress (HS; temperature-humidity index of 72.5 ± 0.2; d 16-20), and (4) HS + euglycemic clamp (EC; glucose infused to reach 100 ± 10% of TN baseline blood glucose for 96 h; d 21-25). Cows were fed and milked twice daily. Feed refusals were collected once daily for calculation of daily dry matter intake, and milk samples were collected at the beginning and end of each period for component analyses. Circulating insulin concentrations were measured in daily blood samples, whereas glucose concentrations were measured more frequently and variably in association with clamp procedures. Rectal temperatures and respiration rates were greater during HS than TN, as expected, and states of hyperinsulinemia and hypoglycemia were successfully induced by the HHC and high ambient temperatures (HS and EC). Feed intake differed based upon thermal environment as it was similar during TN and HHC periods, and declined for HS and EC. Milk production was not entirely reflective of feed intake as it was greatest during TN, intermediate during HHC, and lowest during HS and EC. All milk components differed with the experimental period, primarily in response to the thermal environment. Interestingly, TN baseline glucose concentrations were highly correlated with the change in glucose from TN to HS, and were related to glycemic status during HS. Furthermore, although few in number, those cows that failed to become hypoglycemic during HS tended to have a greater reduction in milk yield. The work presented here addresses a critical knowledge gap by broadening our understanding of the physiological response to heat stress and the related changes in glycemic state. This broadened understanding is fundamental for the development of novel, innovative management strategies as the dairy industry is compelled to become increasingly efficient in spite of global warming.
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Doenças dos Bovinos , Transtornos de Estresse por Calor , Hiperinsulinismo , Hipoglicemia , Insulinas , Animais , Glicemia , Bovinos , Dieta/veterinária , Feminino , Transtornos de Estresse por Calor/veterinária , Resposta ao Choque Térmico , Temperatura Alta , Hiperinsulinismo/veterinária , Hipoglicemia/veterinária , Hipoglicemiantes/farmacologia , Lactação/fisiologia , LeiteRESUMO
BACKGROUND: Treatment of ST-elevation myocardial infarction (STEMI) has improved over the years. Current challenges in the management of STEMI are achievement of early reperfusion and the prevention of microvascular injury. Sonothrombolysis has emerged as a potential treatment for acute myocardial infarction, both for epicardial recanalisation as well as improving microvascular perfusion. This study aims to determine safety and feasibility of sonothrombolysis application in STEMI patients in the ambulance. METHODS: Ten patients with STEMI will be included and treated with sonothrombolysis in the ambulance during transfer to the PCI centre. Safety will be assessed by the occurrence of ventricular arrhythmias and shock during sonothrombolysis intervention. Feasibility will be assessed by the extent of protocol completion and myocardial visibility. Efficacy will be determined by angiographic patency rate, ST-elevation resolution, infarct size and left ventricular volumes, and function measured with cardiovascular magnetic resonance imaging, and contrast and strain echocardiography. A comparison will be made with matched controls using an existing STEMI database. DISCUSSION: Sonothrombolysis is a novel technique for the treatment of cardiovascular thromboembolic disease. The first clinical trials on its use for STEMI have demonstrated promising results. This study will be the first to examine the feasibility of in-ambulance sonothrombolysis for STEMI. TRIAL REGISTRATION: EU Clinical Trials Register (identifier: 2019-001883-31), registered 2020-02-25.
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INTRODUCTION: Infective endocarditis (IE) is associated with a high in-hospital and long term mortality. Although progress has been made in diagnostic approach and management of IE, morbidity and mortality of IE remain high. In the latest European guidelines, the importance of the multi-modality imaging in diagnosis and follow up of IE is emphasized. AIM: The aim was to provide information regarding mortality and adverse events of IE, to determine IE characteristics and to assess current use of imaging in the diagnostic workup of IE. METHODS: This is a prospective observational cohort study. We used data from the EURO-ENDO registry. Seven hospitals in the Netherlands have participated and included patients with IE between April 2016 and April 2018. RESULTS: A total of 139 IE patients were included. Prosthetic valve endocarditis constituted 32.4% of the cases, cardiac device related IE 7.2% and aortic root prosthesis IE 3.6%. In-hospital mortality was 14.4% (20 patients) and one-year mortality was 21.6% (30 patients). The incidence of embolic events under treatment was 16.5%, while congestive heart failure or cardiogenic shock occurred in 15.1% of the patients. Transthoracic and transoesophageal echocardiography were performed most frequently (97.8%; 81.3%) and within 3 days after IE suspicion, followed by 18Ffluorodeoxyglucose positron emission tomography/computed tomography (45.3%) within 6 days and multi-slice computed tomography (42.4%) within 7 days. CONCLUSION: We observed a high percentage of prosthetic valve endocarditis, rapid and extensive use of imaging and a relatively low in-hospital and one-year mortality of IE in the Netherlands. Limitations include possible selection bias.
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Fresh pork color is a function of pigment, and the pH and temperature conditions in the carcass postmortem. To explore the role of scald on color development, carcasses (n = 16) were subjected to either a 4- or 8-min scald. Semimembranosus (SM) muscle samples were collected before and after scalding, and at 24 h postmortem. A 50% reduction in scald time resulted in lighter color (L*) across the muscle early postmortem (P < 0.001), yet the 8-min scald treatment was lighter (P = 0.001) at 24 h. An interaction between scald time and sampling time showed in an increase in L* values at 4-min immediately following scald (P < 0.001). Two-hundred carcasses were then subjected to a modified scald time (6.5 min, or 7.5 min) in an industrial setting. Lowering scald time failed to recapitulate results. In fact, darker meat (L* value; P = 0.0166) was noted in the SM across longer scalds. These data suggest modest changes in scald time may not be responsible for changes in pork quality development.
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Carne de Porco , Carne Vermelha , Animais , Suínos , Temperatura , Fatores de Tempo , Músculo Esquelético/fisiologia , Carne , Concentração de Íons de HidrogênioRESUMO
Variations in color, though a quality frustration, are common across the face of fresh and processed hams. Herein, we measured objective color across the semimembranosus (SM) muscle early postmortem and at 1440 min, then compared these differences against biochemical and metabolic characteristics responsible for pork quality development. Color (L*, a*) differed (P < 0.001) by zone and time but no interaction was evident. Lactate content and pH were highly correlated (R2 = 0.92) at 30 min, but weakened (R2 = 0.161412) by 1440 min. Lactate anaplerosis was not responsible for this lack of relationship. Glycolytic potential also differed across zone (P < 0.001) and time (P < 0.005). Differences in myoglobin expression and abundance, as well as mitochondrial DNA were notable (P < 0.05) across zone. These data suggest inherent differences in SM muscle are key determinants of ham color variation, while postmortem metabolism may play a lesser role in driving this quality attribute.
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Músculos Isquiossurais , Carne , Animais , Cor , Glicólise , Concentração de Íons de Hidrogênio , Carne/análise , Músculo Esquelético/metabolismo , Mioglobina/metabolismo , SuínosRESUMO
In this study, we present a successful simple method for printing and finishing of polyester and cotton fabrics using gold and silver nanoparticles (Au-NPs and Ag-NPs, respectively) as stable, fast colorants and functional components. The surface plasmon resonance (SPR) bands of the colloidal gold and silver NPs were observed at λ max 520 nm and 450 nm, respectively, indicating the presence of spherical Au-NPs and Ag-NPs, which was further confirmed by TEM analysis. The printed samples were subjected to SEM, XRD and EDX analyses. The SEM images and EDX spectra unequivocally confirmed the existence of embedded NPs on the fabric surfaces. Both the cotton and polyester samples possessed excellent color fastness, as indicated from the color fastness test. The functional properties of the printed fabrics indicated that the incorporation of Au-NPs and Ag-NPs into the fabrics simultaneously imparted multifunctional properties such as stable brilliant colors, highly durable antimicrobial activity and very good UV-protection properties.
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PURPOSE OF THE STUDY: Short-term functional results and long-term outcome in terms of stability and wear greatly depend on the precision of the bone cuts. We wanted to know whether conventional ancillaries are still competitive in terms of accuracy in comparison with computer-assisted navigation systems. A few comparative studies favor navigation, but have generally only included a small number of patients. We studied radiographically a prospective consecutive series of 300 total knee prostheses (Innex, Zimmer) implanted with the conventional technique by the same operator. MATERIAL AND METHODS: A telegonometric view in the upright position and a short lateral view were obtained in all patients. In the AP view, implants were measured in comparison with the mechanical axis of the femur (F) and the tibia (T). On the lateral view, the prosthesis-tibial shaft angle (PT) was measured from the proximal portion of the tibial shaft and the prosthesis-femoral shaft angle (PF) from the distal portion of the femur. The same operator made all measurements using the same optimal conditions. The series included 178 women and 122 men, mean age 72 +/- 8 years who presented genu varum (n = 248 knees) and genu valgum (n = 52 knees): degenerative disease (n = 238), polyarthritis (n = 4), hemophilic arthropathy (n = 3), necrosis (n = 3), revision of unicompartmental prosthesis (n = 8), and osteotomy (n = 44). RESULTS: The standard x-ray protocol was performed at two months in all patients. The mechanical axis (HKA) was 179.4 +/- 2.4 degrees (range 173-186 degrees) and was +/- 3 degrees in 87% of knees with no difference for varum and valgum. F was 90.1 +/- 1.4 degrees (87-95), with +/- 3 degrees for 98.7%. T was 89.3 +/- 1.5 degrees (85-94) with +/- 3 degrees for 95.6%. PF was 88.6 +/- 1.6 degrees (84-93) for 87%, PT was 87 +/- 2 degrees (81-93) with +/- 3 degrees for 94%. The four cuts were within +/- 3 degrees for 227 prostheses (77%), within +/- 2 degrees for 156 (52%) and within +/- 1 degrees for 56 (18%). Measurements made again one year after implantation for 203 knees gave the same results. Operative time for implantation was 68 +/- 23 minutes for implantation and 85 +/- 23 minutes including complete closure (less than 60 minutes for 68 knees). DISCUSSION: The accuracy of each cut was satisfactory on average with a small standard deviation. Recent data in the literature show that the accuracy in our series is comparable with that obtained currently with navigation systems. In light of this experience, it can be seen that better precision can be achieved for each of the cuts. CONCLUSION: The accuracy of conventional instrumentation systems is still comparable with that obtained with computer-assisted surgery. The purpose of this study was not to question the benefit of navigation, but to establish a basis upon which progress can be measured. The results enabled a more realistic comparison of the precision of navigation systems and also can be comforting for operators still using conventional ancillaries.
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Artroplastia do Joelho/métodos , Articulação do Joelho/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Artrite/cirurgia , Artroplastia do Joelho/instrumentação , Feminino , Fêmur/diagnóstico por imagem , Fêmur/cirurgia , Seguimentos , Hemartrose/cirurgia , Humanos , Artropatias/cirurgia , Prótese Articular , Articulação do Joelho/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Osteoartrite/cirurgia , Osteonecrose/cirurgia , Osteotomia , Estudos Prospectivos , Radiografia , Reoperação , Cirurgia Assistida por Computador , Tíbia/diagnóstico por imagem , Tíbia/cirurgia , Resultado do TratamentoRESUMO
The German IVF Register (Deutsches IVF-Register [D.I.R]) has been collecting and publishing data on the use of IVF and related methods in Germany since 1982. It is the only institution which provides information for all of Germany on procedures and their success rates. For this reason it plays an important role in the provision of information to the public, to patients, political decision-makers and the scientific community. However, the register does not have the data of all centers offering treatment in Germany nor does it have complete datasets on all reported treatments. The register accepts retrospective data entries, it does not publish the success rates of individual centers and up until 2015 it did not provide a summary of information which was suitable for non-specialists. The D.I.R has been the focus of criticism in the past. Even today, the information it provides to the scientific community, the public, political decision-makers and potential patients on the outcomes of assisted reproduction is insufficient. The documentation of reproductive medicine procedures in other countries is much more meaningful.
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Basic principles governing skeletal muscle growth and development, from a cellular point of view, have been realized for several decades. Skeletal muscle is marked by the capacity for rapid hypertrophy and increases in protein content. Ultimately, skeletal muscle growth is controlled by 2 basic means: 1) myonuclear accumulation stemming from satellite cell (myoblast) proliferation and 2) the balance of protein synthesis and degradation. Each process underlies the rapid changes in lean tissue accretion evident during fetal and neonatal growth and is particularly sensitive to nutritional manipulation. Although multiple signals converge to alter skeletal muscle mass, postprandial changes in the anabolic hormone insulin link feed intake with enhanced rates of protein synthesis in the neonate. Indeed, a consequence of insulin-deficient states such as malnutrition is reduced myoblast activity and a net loss of body protein. A well-characterized mechanism mediating the anabolic effect of insulin involves the phosphatidylinositol 3-kinase (PI3K)-mammalian target of rapamycin (mTOR) signaling pathway. Activation of mTOR leads to translation initiation control via the phosphorylation of downstream targets. Modulation of this pathway by insulin, as well as by other hormones and nutrients, accounts for enhanced protein synthesis leading to efficient lean tissue accretion and rapid skeletal muscle gain in the growing animal. Dysfunctional insulin activity during fetal and neonatal stages likely alters growth through cellular and protein synthetic capacities.
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Insulina/metabolismo , Desenvolvimento Muscular , Músculo Esquelético/crescimento & desenvolvimento , Transdução de Sinais , Animais , Endocrinologia , Fosfatidilinositol 3-Quinases/metabolismo , Fosforilação , Biossíntese de Proteínas , Serina-Treonina Quinases TOR/genética , Serina-Treonina Quinases TOR/metabolismoRESUMO
Background: Patients increasingly use the internet as a source of medical information before initial contact with doctors and during treatment. This applies to reproductive medicine too, where the internet could offer patients the chance to inform themselves in advance about specific procedures and the treatment centres that offer them. In this way it could potentially contribute to informed patient decision-making. This article analyses the web presence of German fertility treatment centres with respect to the provision of information on success rates, risks and side effects of treatment. Methods: Analysis of published success rates and information on the risks and adverse effects of IVF and related methods on German IVF centre websites. Results: Over half of the 129 centres (62.02â%) state a general success rate or their own institution's success rate. Less than a quarter (24.03â%) states their own institution's pregnancy rate and only 7.75â% their own birth rate. The published success rates are mostly pregnancy rates (pregnancy per embryo transfer), which by definition are higher than baby take-home-rates creating unrealistic expectations. Only 61 centres (47.29â%) mention risks and side effects of the procedures offered, and that in varying detail. Only 7 centres (5.43â%) provide information on the risk of psychological stress associated with unsuccessful fertility treatment. Conclusion: There is insufficient opportunity for women and their partners to inform themselves adequately on the internet in advance of treatment about available treatment methods, their success rates and associated risks/side effects; this applies both to specific facilities as well as to the procedures in general. In contrast to other countries, in Germany there is a lack of discussion on content requirements for fertility treatment facility websites.
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The profile of 137Cs, due to Chernobyl accident, in undisturbed soil was measured experimentally over the years 1987 to 1994 and was found to remain practically fixed in the upper 30 cm of soil since 1987. Total deposition of 137Cs at the site was 20 kBq m-2, and approximately 80% of that is in the upper 10 cm. The profile has two slopes in semilogarythmic scale, i.e., it appears as the sum of two exponentials. The contribution of weapons fallout is found to be negligible. Pure diffusion and diffusion-advection models of cesium migration are investigated. It is found that the pure diffusion model cannot reproduce the double slope, while the diffusion advection model can.
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Radioisótopos de Césio/análise , Modelos Teóricos , Reatores Nucleares , Liberação Nociva de Radioativos , Poluentes Radioativos do Solo/análise , Geografia , Grécia , Matemática , Monitoramento de Radiação/métodos , Fatores de Tempo , UcrâniaRESUMO
Following the Chernobyl accident, an area of â¼1000 m(2) in the University farm of the Aristotle University of Thessaloniki was considered as a test ground for radioecological measurements. The radiocesium deposition in this area, due to the Chernobyl accident, was 20 kBq m(-2). The profile of (137)Cs in the soil of this area was measured systematically from 1987 to 2012. The form of the profile has changed over the years. During the 1987-2000 period the (137)Cs distribution was reproducible by a sum of two exponentials. However, at least since 2005 the (137)Cs distribution can be successfully fitted by a single exponential function. The long-time (â¼27 y) evolution study of the (137)Cs distribution in soil permit one to extract with the use of a simple compartment model, the mean vertical migration velocity of (137)Cs. Vertical migration of (137)Cs in soil is a very slow process. The mean vertical migration velocity is estimated to be 0.14 cm y(-1).The relative good comparison between the time dependence of the (137)Cs distribution in soil and the model predictions indicate that the simple model used is realistic.
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Radioisótopos de Césio/análise , Acidente Nuclear de Chernobyl , Modelos Teóricos , Monitoramento de Radiação , Cinza Radioativa/análise , Poluentes Radioativos do Solo/análise , Grécia , Humanos , Doses de Radiação , Fatores de TempoRESUMO
Se conoce como fibromatosis desmoide a la proliferación fibroblástica clonal que surge de partes blandas y se caracteriza por un crecimiento infiltrativo, localmente invasivo y con tendencia a la recurrencia local, pero con baja capacidad de metastatizar. Es un patología infrecuente en la edad padiatrica, sobre todo en la localización de cabeza y cuello. su tratamiento esta en discusión entre la cirugía radical, la conducta expectante y la radio o quimioterapia. Se presenta el caso clínico de un varón de 4 años de edad con diagnostico de fibromatosis desmoide laterocervical de cuello, adyacente a paquete vascular yugulocarotideo, en el cual se practico con éxito la resección total.
Desmoid fibromatosis is a fibroblastic monoclonal proliferation of soft tissues, and is characterized by an infiltrative growth, locally invasive and with tendency to local recurrence, but with a low metastatic capacity . It is an uncommon condition in pediatric patients, especially in head and neck locations. The treatment is under discussion between radical surgery, expectant management and radio or chemotherapy. We report the clinical case of a 4 years old male with a diagnosis of laterocervical desmoid fibromatosis of the neck, adjacent to a vascular jugulocarotide package, in which the total resection was successfully performed.
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Humanos , Masculino , Pré-Escolar , Radioterapia , Fibromatose Agressiva/cirurgia , Fibromatose Agressiva/terapia , Tratamento Farmacológico , Margens de Excisão , Neoplasias de Cabeça e Pescoço/patologiaRESUMO
Metacarpal tuberculosis is a very rare form of the disease; it represents 1% of all bone sites. The diagnosis is often difficult because of the non-specific nature of the clinical examination and X-rays. Specialised morphological investigations are a capital contribution, but histology is diagnostic. Specific chemotherapy, combined with a bony debridement, generally allows desiccation of the bacilli in the lesions and the fixation of bone lesions. We report a case with the intention of pointing out the rarity of this location, the difficulty of diagnosis that may be encountered, and to highlight the severity of bone lesions that are mainly due to their late diagnosis.
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Ossos Metacarpais/microbiologia , Ossos Metacarpais/patologia , Tuberculose Osteoarticular/diagnóstico , Adulto , Antituberculosos/uso terapêutico , Biópsia , Neoplasias Ósseas/diagnóstico , Desbridamento , Diagnóstico Tardio , Diagnóstico Diferencial , Seguimentos , Humanos , Masculino , Índice de Gravidade de Doença , Resultado do Tratamento , Tuberculose Osteoarticular/tratamento farmacológico , Tuberculose Osteoarticular/patologia , Tuberculose Osteoarticular/cirurgiaRESUMO
This study aimed to establish the relationship between ME intake and energy and nutrient absorption across the portal-drained viscera (PDV) of forage-fed beef steers. Eight Angus (328 +/- 40 kg of BW) steers were surgically fitted with portal, mesenteric arterial, and mesenteric venous catheters, and were fed alfalfa cubes in a replicated 4 x 4 Latin square design with 4 levels of energy intake between 1 and 2 times maintenance energy requirements. On d 28 of each experimental period, p-aminohippuric acid was infused to measure blood and plasma flow across the PDV, and blood samples (1 every hour, for 6 h) were collected simultaneously from arterial and venous catheters for net absorption measurements. Oxygen utilization, and therefore energy utilization, increased (P < 0.05) linearly in relation to ME intake. Glucose net uptake was unaffected, but lactate net release increased linearly in response to ME intake (P < 0.05). Net absorption of all AA except tryptophan, glutamate, and glutamine increased linearly with ME intake (P < 0.05). The constant net absorption of glutamate and glutamine indicated increased net utilization of these AA when dietary supply was increased. These data provide quantitative measures of the PDV effects on energy and AA availability for productive tissues, and suggest that the greater net utilization of some AA when ME intake is increased could relate to their catabolism for energy production. Prediction estimates of small intestinal AA absorption, based on the Cornell Net Carbohydrate and Protein System (CNCPS), exceeded observed net AA PDV absorption. Mean bias represented the greatest proportion (87 to 96%) of the deviation between individual AA absorption and observed net AA PDV absorption, suggesting that the CNCPS model may be used to predict AA net absorption when factors describing AA utilization by the PDV are applied to model predictions.
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Fenômenos Fisiológicos da Nutrição Animal , Bovinos/metabolismo , Trato Gastrointestinal/metabolismo , Medicago sativa , Modelos Biológicos , Sistema Porta/fisiologia , Aminoácidos/sangue , Animais , Glicemia/metabolismo , Ingestão de Alimentos/fisiologia , Ingestão de Energia , Trato Gastrointestinal/irrigação sanguínea , Hemoglobinas/metabolismo , Absorção Intestinal , Ácido Láctico/sangue , Masculino , Consumo de Oxigênio/fisiologia , Ácido p-Aminoipúrico/farmacologiaRESUMO
The aims of this study were 1) to determine whether transfer of blood urea to the gastrointestinal tract (GIT) or the efficiency of capture of urea N within the GIT is more limiting for urea N salvage, and 2) to establish the relationship between plasma urea concentration and recycling of urea N to the GIT. We used an i.v. urea infusion model in sheep to elevate the urea entry rate and plasma concentrations, thus avoiding direct manipulation of the rumen environment that otherwise occurs when feeding additional N. Four growing sheep (28.1 +/- 0.6 kg of BW) were fed a low-protein (6.8% CP, DM basis) diet and assigned to 4 rates of i.v. urea infusion (0, 3.8, 7.5, or 11.3 g of urea N/d; 10-d periods) in a balanced 4 x 4 Latin square design. Nitrogen retention (d 6 to 9), urea kinetics([(15)N2]urea infusion over 80 h), and plasma AA were determined. Urea infusion increased apparent total tract digestibility of N (29.9 to 41.3%) and DM (47.5 to 58.9%), and N retention (1.45 to 5.46 g/d). The plasma urea N entry rate increased (5.1 to 21.8 g/d) with urea infusion, as did the amount of urea N entering the GIT (4.1 to 13.2 g/d). Urea N transfer to the GIT increased with plasma urea concentration, but the increases were smaller at greater concentrations of plasma urea. Anabolic use of urea N within the GIT also increased with urea infusion (1.43 to 2.98 g/d; P = 0.003), but anabolic use as a proportion of GIT entry was low and decreased (35 to 22%; P = 0.003) with urea infusions. Consequently, much (44 to 67%) of the urea N transferred to the GIT returned to the liver for resynthesis of urea (1.8 to 9.2 g/d; P < 0.05). The present results suggest that transfer of blood urea to the GIT is 1) highly related to blood urea concentration, and 2) less limiting for N retention than is the efficiency of capture of recycled urea N by microbes within the GIT.
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Nitrogênio da Ureia Sanguínea , Digestão/fisiologia , Sistema Digestório/metabolismo , Ovinos/metabolismo , Ureia/sangue , Aminoácidos/sangue , Ração Animal , Fenômenos Fisiológicos da Nutrição Animal , Animais , Dieta/veterinária , Nitrogênio/metabolismo , Ureia/administração & dosagemRESUMO
Genomic investigations in animals have begun to reveal the metabolic and physiological functions of genes and protein products. However, a thorough understanding of the genomic roadmaps will require investigative approaches that yield qualitative and quantitative information on the activities, fluxes, and connectivity of pathways involved in nutrient use in farm animals; that is, the metabolic phenotype. Recently, the commercial availability of stable isotope (13C, 15N, 2H)-labeled compounds and highly accurate mass spectrometers has made it possible to probe the details of metabolic pathways involved in macronutrient use. For years, the biological sciences have exploited uniformly 13C-labeled substrates (e.g., glucose, amino acids, nucleic acids) and 13C-mass isotopomer distribution (MID) in their metabolic investigations, whereas their use in the animal sciences is very limited. When [U-13C] substrates are fed, infused, or added to cell incubations, the 13C-skeletons distribute throughout metabolic networks. 13C-Mass isotopomer distribution in intermediates and end products of the pathways provides a signature of the fluxes and activities of pathway enzymes traveled by the precursor molecule. This paper highlights aspects of animal nutrition and metabolism in which [U-13C] substrates and MID can be applied to investigations of amino acid, carbohydrate, and fat metabolism. We will focus on [U-13C] glucose as a tracer in chickens, fish, sheep, and cell cultures to investigate the interconnectivity of the pathways of macronutrient and nucleic acid metabolism, and provide demonstration of the central position of the Krebs cycle in preserving metabolic flexibility via anaplerotic and cataplerotic sequences. Exploitation of this approach in animal sciences offers endless opportunities to provide missing details of the biochemical networks of nutrient use that may prove to be strictly under genomic control.