Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 21
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
J Laryngol Otol ; 122(12): 1309-17, 2008 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18808729

RESUMO

OBJECTIVE: Recent research has indicated that sphingosine 1-phosphate plays a role in allergy. This study examined the effect of allergen challenge on the expression of sphingosine 1-phosphate receptors on the eosinophils of allergic rhinitis patients, and the effect of steroid treatment on this expression. STUDY DESIGN: A prospective, non-randomised study. METHODS: The study had three parts. Firstly, sphingosine 1-phosphate receptor expression on the eosinophils of allergic rhinitis patients and control patients was determined. Secondly, sphingosine 1-phosphate receptor expression was quantified pre- and post-allergen challenge, before and after a short course of fluticasone propionate; all patients underwent symptom scoring and peak nasal inspiratory flow measurement pre- and post-allergen challenge, both before and after steroid or saline treatment. Thirdly, the effect of sphingosine 1-phosphate on eosinophil migration was examined. RESULTS: The eosinophils of both allergic rhinitis patients and controls expressed sphingosine 1-phosphate1, 3, 4, and 5. Eosinophils from all allergic rhinitis patients demonstrated up-regulation in sphingosine 1-phosphate expression after allergen challenge. These changes were statistically very significant for sphingosine 1-phosphate1, 4, and 5, and moderately significant for sphingosine 1-phosphate3. Sphingosine 1-phosphate receptor expression up-regulation was abolished in the steroid-treated group after allergen challenge; however, the saline-treated group showed no change in sphingosine 1-phosphate receptor expression after allergen challenge. Peak nasal inspiratory flow scores were significantly diminished after allergen challenge prior to treatment, but not after a course of topical nasal steroids. Sphingosine 1-phosphate induced eosinophil chemotaxis was increased following allergen challenge in allergic rhinitis subjects. CONCLUSIONS: Local intranasal steroid therapy acts directly to block allergen-induced up-regulation of sphingosine 1-phosphate receptors on the peripheral eosinophils of allergic rhinitis patients, and this is coincident with post-challenge peak nasal inspiratory flow measurement improvements. These observations support the idea that such an increase in sphingosine 1-phosphate receptor expression is clinically relevant in allergic rhinitis, with potential consequences for eosinophil migration and survival.


Assuntos
Eosinófilos/metabolismo , Receptores de Lisoesfingolipídeo/metabolismo , Rinite Alérgica Perene/metabolismo , Administração Tópica , Adulto , Androstadienos/uso terapêutico , Movimento Celular/efeitos dos fármacos , Células Cultivadas , Eosinófilos/efeitos dos fármacos , Feminino , Fluticasona , Expressão Gênica/efeitos dos fármacos , Humanos , Masculino , Pessoa de Meia-Idade , Testes de Provocação Nasal , Estudos Prospectivos , Receptores de Lisoesfingolipídeo/administração & dosagem , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Rinite Alérgica Perene/tratamento farmacológico , Esteroides/administração & dosagem , Regulação para Cima/efeitos dos fármacos , Adulto Jovem
2.
J Dairy Sci ; 90(2): 721-30, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17235149

RESUMO

Conjugated linoleic acid (CLA) reduces milk fat synthesis in grazing dairy cows and may improve calculated net energy balance (EBAL). Study objectives were to determine whether CLA-induced milk fat depression could be utilized during times of feed restriction to improve bioenergetic and milk production parameters. Twelve multiparous rumen-fistulated Holstein cows (204 +/- 7 d in milk) were offered ad libitum (AL) or restricted (R) pasture and abomasally infused twice daily with 0 (control) or 50 g/d of CLA (CLA; mixed isomers) in a 2-period crossover design. Treatment periods lasted 10 d and were separated by a 10-d washout period. Milk and plasma samples were averaged from d 9 and 10, and EBAL was calculated from d 6 to 10 of the infusion period. Pasture restriction reduced the yield of milk (3.9 kg/d) and milk components. The CLA treatment reduced milk fat yield by 44 and 46% in AL and R, respectively. There was no effect of CLA on milk yield or milk lactose content or yield in either feeding regimen; however, CLA increased the milk protein content and yield by 7 and 6% and by 5 and 8%, in AL and R, respectively. The CLA-induced changes to milk fat and protein doubled the protein:fat ratio in both AL and R. Calculated EBAL improved following the CLA infusion (-0.44 vs. 2.68 and 0.38 vs. 3.29 Mcal/d for AL and R, respectively); however, CLA did not alter plasma bioenergetic markers. Data indicate that during short periods of nutrient limitation, supplemental CLA may be an alternative management tool to enhance protein synthesis and improve the milk protein:fat ratio and calculated EBAL in cows grazing pasture. Further studies are required to determine whether CLA is effective at improving bioenergetic and production parameters during more severe or longer term nutrient restriction.


Assuntos
Bovinos/fisiologia , Dieta , Metabolismo Energético/efeitos dos fármacos , Lactação/efeitos dos fármacos , Ácidos Linoleicos Conjugados/administração & dosagem , Abomaso/efeitos dos fármacos , Fenômenos Fisiológicos da Nutrição Animal , Animais , Suplementos Nutricionais , Ingestão de Energia , Ácidos Graxos/análise , Feminino , Concentração de Íons de Hidrogênio , Lactose/análise , Lipídeos/análise , Leite/química , Leite/efeitos dos fármacos , Proteínas do Leite/análise , Nitrogênio/análise
3.
J Laryngol Otol ; 121(4): 358-61, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-17064460

RESUMO

OBJECTIVE: The aim of this study was to compare the subjective tracheoesophageal pressure symptoms associated with substernal goitres with objective cross-sectional radiographic measurements. DESIGN: Patients with substernal goitre were questioned regarding tracheoesophageal compression symptoms and these data were analysed for correlation with radiographic and intra-operative findings. RESULTS: Twenty-six patients were included. Patients with airway symptoms including dyspnoea, stridor and coughing were more likely to have significant tracheal narrowing on pre-operative computed tomography (CT) imaging. There was also a significant correlation between the perceived severity of lump sensation in the throat and the presence of tracheal and oesophageal displacement and retrotracheal extension of the thyroid mass. CONCLUSION: Pre-operative CT measurements of tracheal and oesophageal displacement, retrotracheal extension and the degree of tracheal compression correlate well with the presence and severity of tracheoesophageal pressure symptoms. None of the radiographic findings that are exclusive to substernal goitre (percentage of substernal mass, goitre size at the level of the thoracic inlet, ratio of goitre size to the vertebral body at the thoracic inlet and retrosternal isthmus size) had any correlation with clinical symptoms in this study.


Assuntos
Obstrução das Vias Respiratórias/diagnóstico por imagem , Doenças do Esôfago/diagnóstico por imagem , Bócio Subesternal/diagnóstico por imagem , Glândula Tireoide/diagnóstico por imagem , Doenças da Traqueia/diagnóstico por imagem , Feminino , Bócio Subesternal/cirurgia , Humanos , Masculino , Pessoa de Meia-Idade , Índice de Gravidade de Doença , Inquéritos e Questionários , Tomografia Computadorizada por Raios X
4.
J Laryngol Otol ; 120(5): 393-6, 2006 May.
Artigo em Inglês | MEDLINE | ID: mdl-16563198

RESUMO

INTRODUCTION: The study sought to compare and contrast squamous cell carcinoma (SCC) of the anterior mobile tongue with SCC of the tongue base, with emphasis on clinical presentation, management and outcome. METHODS: This was a retrospective, comparative analysis of patients treated for SCC of the tongue over a 10-year period. Cox's regression model was used to assess the effect of tumour site on survival. RESULTS: The study included 142 patients, of whom 86 were treated for SCC of the anterior tongue and 56 for tongue base lesions. Patients with carcinoma of the anterior tongue tended to present with a visible lump or ulceration of the tongue, whereas the majority of patients with tongue base SCC presented with pain. Sixty per cent of anterior tongue lesions were early stage (I or II) at initial presentation as compared with 21 per cent of tongue base lesions. CONCLUSION: Patients with anterior tongue lesions had a better prognosis, but this was not statistically significant when adjusted for stage.


Assuntos
Carcinoma de Células Escamosas/patologia , Neoplasias da Língua/patologia , Adulto , Distribuição por Idade , Idoso , Idoso de 80 Anos ou mais , Carcinoma de Células Escamosas/mortalidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Prognóstico , Análise de Regressão , Estudos Retrospectivos , Distribuição por Sexo , Taxa de Sobrevida , Neoplasias da Língua/mortalidade
6.
Int J Pediatr Otorhinolaryngol ; 70(3): 425-8, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16125254

RESUMO

OBJECTIVE: This study reviews the management of children with foreign bodies in the nose or ear in an attempt to see whether these children can be successfully managed in the Accident and Emergency (A & E) Department or whether they should be directly referred to the Otolaryngology service. METHODS: The records of all children with a foreign body in either the nose or ear who presented to the Accident and Emergency Department at The National Children's Hospital over a 2-year period were reviewed. RESULTS: 82 children presented with a foreign body in the nose and 53 (65%) were successfully managed in the A & E Department. In contrast, of the 58 children with a foreign body in the ear only 4 (7%) were successfully removed in the A & E Department. CONCLUSION: Most foreign bodies in the nose can be successfully removed in the Accident and Emergency Department. In contrast there is a high failure rate in removal of foreign bodies from the ear in the A & E Department and these should be referred directly to the ENT service.


Assuntos
Acidentes , Orelha , Serviços Médicos de Emergência , Corpos Estranhos/cirurgia , Nariz , Procedimentos Cirúrgicos Otorrinolaringológicos/métodos , Adolescente , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino
7.
J Dairy Sci ; 87(2): 369-78, 2004 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-14762080

RESUMO

New Zealand Holstein-Friesian cows (n = 4) were used to quantify the importance of endogenous synthesis of cis-9, trans-11 conjugated linoleic acid (CLA) via Delta(9)-desaturase in cows fed a fresh pasture diet. The experiment was a 4 x 4 Latin square design with treatments arranged in a 2 x 2 factorial. Treatments lasted 4 d and were pasture only, pasture plus sterculic oil, pasture plus sunflower oil, and pasture plus sunflower oil plus sterculic oil. Abomasal infusion of sterculic oil inhibited Delta(9)-desaturase and decreased the concentration of cis-9, trans-11 CLA in milk fat by 70%. Using the changes in cis-9 10:1, cis-9 12:1 and cis-9 14:1 to correct for incomplete inhibition of Delta(9)-desaturase, a minimum estimate of 91% of cis-9, trans-11 CLA in milk fat was produced endogenously in cows fed fresh pasture. Dietary supplementation of a pasture diet with sunflower oil increased the proportion of long chain fatty acids in milk fat; however, the increase in vaccenic acid concentration was small (18%) and there was no increase in cis-9, trans-11 CLA concentration. Overall, results show that endogenous synthesis is responsible for more than 91% of the cis-9, trans-11 CLA secreted in milk fat of cows fed fresh pasture. However, the failure of plant oil supplements to increase the concentration of cis-9, trans-11 CLA in milk fat from pasture-fed cows requires further investigation.


Assuntos
Bovinos/metabolismo , Dieta , Ácidos Linoleicos Conjugados/biossíntese , Animais , Inibidores Enzimáticos/farmacologia , Feminino , Ácidos Linoleicos Conjugados/análise , Leite/química , Ácidos Oleicos/análise , Óleos de Plantas/administração & dosagem , Estearoil-CoA Dessaturase/antagonistas & inibidores , Estearoil-CoA Dessaturase/metabolismo , Sterculia/química , Óleo de Girassol
8.
J Dairy Sci ; 86(11): 3508-15, 2003 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-14672180

RESUMO

In lactating dairy cows, the onset of negative net energy balance (EB) at parturition causes a reduction in plasma leptin and is also associated with increased concentration of growth hormone (GH) and decreased concentration of insulin. These observations raise the possibility that opposite changes in plasma insulin and GH are partly responsible for reduced plasma leptin. To test this hypothesis, we first examined the effects of undernutrition without the confounding influence of parturition by using late lactating dairy cows fed 120% of their nutrient requirements or restricted to 33% of maintenance requirements. Plasma leptin was reduced within 24 h of feed restriction, and was associated with increased plasma GH and decreased plasma insulin. Complete food deprivation for 48 h caused similar changes in the plasma concentration of leptin. To determine if an elevation in GH is responsible for the fall in plasma leptin, dairy cows were treated with excipient or bovine somatotropin in early lactation or in late lactation. Growth hormone treatment had no significant effect on plasma leptin irrespective of stage of lactation. Finally, the effects of insulin were studied by performing euglycemic hyperinsulinemic clamps in mid-lactating dairy cows. After 96 h of hyperinsulinemia, plasma leptin was increased significantly. These data indicate that insulin regulates plasma leptin in lactating dairy cows. They also suggest that, in undernourished lactating dairy cows, reduced plasma insulin could account for a portion of the decline in plasma leptin but that elevated plasma GH is unlikely to have a major effect.


Assuntos
Bovinos/fisiologia , Hormônio do Crescimento/sangue , Insulina/fisiologia , Lactação/fisiologia , Leptina/metabolismo , Fenômenos Fisiológicos da Nutrição Animal , Animais , Bovinos/sangue , Feminino , Privação de Alimentos/fisiologia , Técnica Clamp de Glucose , Insulina/sangue , Lactação/sangue , Leptina/sangue , Parto/sangue , Parto/fisiologia , Período Pós-Parto/sangue , Período Pós-Parto/fisiologia , Distribuição Aleatória
9.
J Dairy Sci ; 86(2): 644-52, 2003 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-12647970

RESUMO

The aim of this study was to investigate the effects of conjugated linoleic acid supplementation on the synthesis of milk fat in pasture-fed Friesian cows. In four cows, a commercial mixture containing 62.3% (wt/vol) conjugated linoleic acid was infused intraabomasally to avoid rumen fermentation and biohydrogenation. The design was a 4 x 4 Latin square in which each cow received infusions of 0, 20, 40, and 80 g/d of conjugated linoleic acid mixture for 4 d. Cows were fed freshly cut ryegrass/white clover pasture ad libitum. Milk fat concentration was decreased by 36, 43, and 62% and milk fat yield was decreased by 32, 36, and 60% by the 20, 40, and 80 g of conjugated linoleic acid/d treatments. Dry matter intake, milk protein concentration, and protein yield were unaffected by treatments; however, milk yield was increased by 11% during the 40-g conjugated linoleic acid/d treatment. The effects of conjugated linoleic acid infusion were most pronounced in reducing de novo fatty acid synthesis and desaturation. Results show that the inhibitory effect of this conjugated linoleic acid mixture on milk fat synthesis occurs in pasture-fed cows, and demonstrate the potential to dramatically alter gross milk composition. This technology could offer a management tool to manipulate milk composition and energy demands of pasture-fed cows.


Assuntos
Abomaso/efeitos dos fármacos , Bovinos/fisiologia , Lactação , Ácido Linoleico/administração & dosagem , Lipídeos/análise , Leite/química , Fenômenos Fisiológicos da Nutrição Animal , Animais , Dieta , Suplementos Nutricionais , Ácidos Graxos não Esterificados/sangue , Feminino , Proteínas do Leite/análise
11.
Ir J Med Sci ; 171(1): 40-1, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-11993594

RESUMO

UNLABELLED: BACKGROUND Prenatal ultrasonography predicting airway obstruction can facilitate intrapartum management, revolutionising the approach to potential airway difficulties at birth. AIMS: This report presents the first case of this procedure attempted in Ireland. RESULT AND CONCLUSION: This case was unsuccessful in securing an airway, but the potential for intubation or tracheostomy with an intact maternal-foetal circulation provides encouragement for the management of future cases.


Assuntos
Obstrução das Vias Respiratórias/diagnóstico por imagem , Circulação Placentária , Ultrassonografia Pré-Natal , Adulto , Feminino , Humanos , Intubação Intratraqueal , Linfangioma Cístico/diagnóstico por imagem , Gravidez , Prega Vocal/anormalidades
12.
Ir Med J ; 94(7): 208, 210, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11693211

RESUMO

We designed a study to ascertain the weight and type of items carried by junior hospital doctors in their white coats. Sixty consecutive doctors entering the hospital residence were invited to participate, 54 agreed. White coat contents were itemised and weighed. Mean weight carried was 1.63 Kg. Interns and SHOs carried significantly more than registrars (P<0.01) & (P<0.05). Medical specialties carried significantly more than surgical specialties (P<0.05). There were no statistical difference between males and females. 33% carried cigarettes. Junior hospital doctors carry the equivalent of almost two 1Kg bags of sugar with them in their white coats, this added weight may contribute to increased fatigue during long hours on duty. As doctors become more senior they carry less.


Assuntos
Vestuário/estatística & dados numéricos , Corpo Clínico Hospitalar/estatística & dados numéricos , Mobilidade Ocupacional , Fadiga/etiologia , Feminino , Humanos , Masculino , Resistência Física , Obras de Referência , Estetoscópios , Carga de Trabalho
14.
Int J Pediatr Otorhinolaryngol ; 60(2): 163-5, 2001 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-11518595

RESUMO

Foreign body aspiration is a common problem in children necessitating prompt recognition and early treatment to minimize the potentially serious and sometimes even fatal consequences. We report the case of a 7 year old girl with a peanut lodged in her right main bronchus. Bronchoscopy identified the foreign body which was then removed by the combined use of a Fogarty balloon catheter and extraction forceps. This case differs from previous reports, in that the foreign body and forceps were removed separately from the balloon catheter, which theoretically should minimize the risks associated with this procedure.


Assuntos
Brônquios , Cateterismo/instrumentação , Corpos Estranhos/terapia , Broncoscopia , Cateterismo/métodos , Criança , Feminino , Seguimentos , Corpos Estranhos/diagnóstico , Humanos , Medição de Risco , Instrumentos Cirúrgicos , Resultado do Tratamento
15.
J Dairy Sci ; 83(9): 2069-74, 2000 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11003240

RESUMO

The objective of this study was to determine whether the differences in the composition of milk from cows of different beta-lactoglobulin beta-LG) phenotypes are affected by the amount of pasture available and, hence, pasture dry matter intake. Twenty-two Friesian cows of each of the AA and BB variants of the beta-LG phenotype were subjected to ad libitum grazing or restricted grazing in crossover experiments during spring (early lactation, approximately 60 d in milk) and summer (mid to late lactation, approximately 180 d in milk). Milk samples were collected from each cow at the end of each 8-d treatment period and analyzed for composition. Cows of the AA variant of the beta-LG phenotype had higher concentrations of whey protein and beta-LG, but lower concentrations of casein (CN), alpha-CN, kappa-CN (summer only), and BSA, than cows of the BB variant. Compared with cows with a restricted allowance, cows grazing ad libitum had higher milk yields and concentrations of protein, casein, whey protein, and all individual proteins except BSA and immunoglobulin. There were no interactions between effects of pasture allowance and phenotype on milk yield or composition. The data show that having adequate pasture for grazing cows is important not only to maximize milk yield, but also to optimize concentrations of protein and casein, and hence the manufacturing potential of milk. Further, the differences in composition of milk from cows of differing beta-LG phenotypes persisted during short-term restrictions in pasture allowance, and between spring and summer.


Assuntos
Fenômenos Fisiológicos da Nutrição Animal , Bovinos/genética , Lactação/genética , Lactoglobulinas/genética , Leite/química , Animais , Bovinos/fisiologia , Ingestão de Energia , Feminino , Variação Genética , Lactoglobulinas/análise , Leite/metabolismo , Proteínas do Leite/análise , Proteínas do Leite/genética , Fenótipo , Poaceae , Estações do Ano
16.
J Dairy Sci ; 83(8): 1740-9, 2000 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10984150

RESUMO

Two experiments investigated the regulation of milk protein synthesis in well-fed cows (n = 4) using 1) a hyperinsulinemic-euglycemic clamp and 2) intramammary infusion of insulin or long R3 insulin-like growth factor-I plus supplementary amino acids. In experiment 1, insulin was infused at 1.0 microg x kg BW(-1) x h(-1) to increase circulating levels fourfold, and euglycemia was maintained by infusion of glucose. An insulin clamp increased the yields of casein and whey protein both with and without supplementary amino acids. Plasma concentrations of insulin-like growth factor-I were increased and insulin-like growth factor binding protein-2 decreased during insulin clamp, while both insulin and insulin-like growth factor-I in milk were elevated by this treatment. Milk concentrations of insulin peaked on day 4, but insulin-like growth factor-I concentrations in milk peaked on day 1 of the insulin clamp. In experiment 2, intramammary infusion of insulin had no effects on any measured variables, while yields of milk, protein, and fat were slightly lower following long R3 insulin-like growth factor-I treatment. This could be associated with an increase in somatic cell count, which occurred following long R3 insulin-like growth factor-I treatment. Results from experiment 1 suggest insulin and insulin-like growth factor-I are likely candidates responsible for the increased milk protein yields during the insulin clamp. However, in experiment 2 neither hormone enhanced milk protein yield when administered using an intramammary technique.


Assuntos
Fator de Crescimento Insulin-Like I/farmacologia , Insulina/farmacologia , Proteínas do Leite/efeitos dos fármacos , Leite/efeitos dos fármacos , Abomaso , Aminoácidos/administração & dosagem , Animais , Glicemia/metabolismo , Bovinos , Indústria de Laticínios , Feminino , Técnica Clamp de Glucose , Infusões Parenterais , Insulina/administração & dosagem , Insulina/sangue , Fator de Crescimento Insulin-Like I/administração & dosagem , Leite/química , Proteínas do Leite/metabolismo , Gravidez , Fatores de Tempo
17.
J Dairy Sci ; 83(6): 1300-9, 2000 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-10877395

RESUMO

We investigated the contribution of plasma and red blood cells to amino acid (AA) supply for milk protein synthesis during a combination of treatments that included abomasal infusion of casein and AA and utilization of a hyperinsulinemic-euglycemic clamp. Treatments resulted in substantial differences in circulating concentrations of AA, mammary uptake of AA, and rates of milk protein synthesis. Arterial concentrations of all AA in plasma were highly correlated with that of whole blood. Concentrations of AA in red blood cells were either higher (Asn+Asp, Gly, His, Leu, Met, Orn, Ser, Tau, Thr, and Tyr), lower (Ala, Arg, Cit, Cys, Ile, and Val), or similar (Gln+Glu, Phe, and Pro) to that of plasma. Arteriovenous difference measurements demonstrated that interorgan transfer of AA to the mammary gland was primarily by plasma. There was little involvement of red blood cells except for small quantities of Leu, Met, and Thr to the mammary gland; this contribution was greatest for Met and accounted for 14% of the total mammary uptake. Countercurrent transport of Gln + Glu, Asn + Asp, and Pro was also evident where these AA were extracted from plasma, but were released into red blood cells as blood passed through the mammary gland. This net influx of Gln+Glu, Asn+Asp, and Pro into red blood cells was equivalent to 26, 17, and 30% of their mammary uptake from plasma. Overall, the interorgan transport of free AA for the mammary gland was predominantly by plasma, and red blood cells were limited to minor contributions in mammary uptake for a few AA. Furthermore, arteriovenous differences of essential AA across the mammary gland were highly correlated between plasma and whole blood.


Assuntos
Aminoácidos/metabolismo , Mama/metabolismo , Bovinos/fisiologia , Eritrócitos/metabolismo , Plasma/metabolismo , Animais , Feminino , Lactação/metabolismo , Proteínas do Leite/biossíntese
18.
J Dairy Sci ; 83(1): 93-105, 2000 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-10659969

RESUMO

We examined the relationships between amino acid supply, net utilization of amino acid by the mammary gland, and milk protein yield, in investigations that utilized a hyperinsulinemic-euglycemic clamp. A two-way crossed factorial design was employed. There were two 12-d periods involving abomasal infusions of either water or a mixture of casein (500 g/d) plus branched-chain amino acids (88 g/d), with a hyperinsulinemic-euglycemic clamp during the last 4 d of each period. During the clamp, insulin was infused at 1.0 microg x kg BW(-1) x h(-1) to increase circulating levels fourfold, and euglycemia was maintained by infusion of glucose. The insulin clamp treatments increased milk protein yield by 15 and 25% during abomasal infusion of water or casein plus branched-chain amino acids, respectively. Circulating concentrations of essential amino acids were reduced (33%) during insulin clamp treatments, especially branched-chain amino acids (41%). Arteriovenous difference of essential amino acids across the mammary gland was linearly related to their arterial concentrations. However, milk protein yield was not related to either arterial concentration or arteriovenous difference, for any of the essential amino acids. During insulin clamp treatments, the mammary gland was able to support the increased milk protein yields by increasing extraction efficiency of essential amino acids, mammary blood flow, and glucose uptake. Furthermore, a positive mammary balance of total amino nitrogen and carbon was maintained for all treatments. These adaptations demonstrate the unique ability of the mammary gland to adjust local conditions to allow for an adequate nutrient supply.


Assuntos
Aminoácidos/metabolismo , Bovinos/metabolismo , Insulina/farmacologia , Glândulas Mamárias Animais/metabolismo , Proteínas do Leite/biossíntese , Proteínas/farmacologia , Abomaso , Aminoácidos/sangue , Aminoácidos de Cadeia Ramificada/sangue , Aminoácidos Essenciais/sangue , Animais , Artérias , Caseínas/administração & dosagem , Feminino , Técnica Clamp de Glucose , Insulina/administração & dosagem , Glândulas Mamárias Animais/irrigação sanguínea , Glândulas Mamárias Animais/efeitos dos fármacos , Proteínas/administração & dosagem
19.
J Dairy Sci ; 82(7): 1512-24, 1999 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-10416166

RESUMO

Our study investigated the effect of insulin on the regulation of milk protein synthesis in well-fed cows (n = 4) with or without additional amino acids (AA). The design was a two-way crossed factorial with two 12-d periods involving abomasal infusions of either water or a mixture of casein (500 g/d) plus branched-chain AA (88 g/d). During the last 4 d of each period a hyperinsulinemic-euglycemic clamp was performed; insulin was infused at 1.0 microgram.kg of BW-1.h-1 to increase circulating levels fourfold, and euglycemia was maintained by infusion of glucose. Cows were fed a diet formulated to exceed requirements for metabolizable energy and protein. During abomasal water infusion, the insulin clamp increased milk protein yields by 15% (+128 g/d); when combined with abomasal infusion of casein plus branched-chain AA, milk protein yield was increased by 25% (+213 g/d). These increases resulted from equivalent increases in milk protein concentration and milk yield. Concentrations of casein and whey proteins in milk were increased by insulin clamp treatments; however, there were no major changes in the relative proportions of individual casein and whey proteins. Plasma concentrations of essential AA were reduced (-33%) during the insulin clamp treatments; effects were most dramatic for the branched-chain AA (-41%) and their keto acids (-45%). Results confirm the important regulatory role of the endocrine system in milk protein synthesis and demonstrate this potential to produce milk protein is not fully expressed.


Assuntos
Aminoácidos/farmacologia , Insulina/farmacologia , Proteínas do Leite/metabolismo , Leite/metabolismo , Abomaso , Aminoácidos/administração & dosagem , Animais , Glicemia/efeitos dos fármacos , Glicemia/metabolismo , Nitrogênio da Ureia Sanguínea , Caseínas/administração & dosagem , Bovinos , Indústria de Laticínios , Análise Fatorial , Ácidos Graxos não Esterificados/sangue , Feminino , Técnica Clamp de Glucose , Infusões Parenterais , Insulina/administração & dosagem , Insulina/sangue , Lactação , Leite/química , Leite/efeitos dos fármacos , Proteínas do Leite/análise , Fatores de Tempo
20.
J Dairy Sci ; 82(1): 161-71, 1999 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-10022018

RESUMO

Our study investigated the separate and combined effects of branched-chain amino acids (AA) and sodium caseinate on milk protein concentration and yield. Four Holstein cows (112 d in milk) were abomasally infused with water, branched-chain AA (150 g/d), sodium caseinate (600 g/d), or branched-chain AA plus sodium caseinate (44 and 600 g/d, respectively) according to a 4 x 4 Latin square design with 8-d treatment periods. Cows were fed a dry diet based on alfalfa hay and concentrates for ad libitum intake. The ration was formulated to exceed requirements for metabolizable energy and protein using the Cornell Net Carbohydrate and Protein System. Neither daily dry matter intake (24.2 +/- 0.4 kg/d; X +/- SEM) nor milk yield (32.9 +/-; 0.4 kg/d) was affected by any of the infusion treatments. Infusion of branched-chain AA had no effect on any milk production parameters, despite a 50% increase in their concentrations. Modest increases in milk protein concentration (0.1%) and milk protein yield (62 g/d) resulted from the infusion of sodium caseinate or branched-chain AA plus sodium caseinate. True protein and whey protein concentrations in milk were also marginally increased by infusion of sodium caseinate and branched-chain AA plus sodium caseinate, and infusion of branched-chain AA, sodium caseinate, or both elevated milk nonprotein N content. Plasma urea N concentrations were elevated by the sodium caseinate and branched-chain AA plus sodium caseinate treatments. No treatment effects on other plasma metabolites or hormones were observed. Our results show no benefit of supplementation with branched-chain AA and only modest effects of sodium caseinate on milk protein concentration and yield in well-fed cows.


Assuntos
Aminoácidos de Cadeia Ramificada/farmacologia , Caseínas/farmacologia , Bovinos/metabolismo , Lactação/efeitos dos fármacos , Proteínas do Leite/metabolismo , Abomaso/efeitos dos fármacos , Aminoácidos/sangue , Aminoácidos de Cadeia Ramificada/administração & dosagem , Animais , Glicemia/metabolismo , Nitrogênio da Ureia Sanguínea , Caseínas/administração & dosagem , Dieta , Ingestão de Alimentos , Feminino , Insulina/sangue , Medicago sativa , Proteínas do Soro do Leite
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...