RESUMO
OBJECTIVES: This qualitative study explored public attitudes to COVID-19 vaccines in children, including reasons for support or opposition to them. STUDY DESIGN: This was a qualitative study using online focus groups and interviews. METHODS: Group and individual online interviews were conducted with a diverse sample of 24 adults in the United Kingdom to explore their views on the issue of COVID-19 vaccination in children. Data were analysed using a framework approach. RESULTS: COVID-19 vaccination in children was framed as a complex problem (a 'minefield'). Six themes emerged to explain participants views: (1) uncertainty over whether children can catch, transmit or be severely harmed by COVID-19; (2) lower risk tolerance for unknown longer term effects of the vaccine in children; (3) association of the vaccine programme with government's handling of the pandemic; (4) local social norms as a driver of hesitancy; (5) vaccinating children as a way to protect vulnerable adults; and (6) children's vaccination as parental choice. CONCLUSIONS: COVID-19 vaccination in children is perceived by members of the public as a complex issue, and many are torn or hesitant about the idea. Public health communications will need to combat this hesitancy if vaccine uptake for children is to be pursued as a public health policy.
Assuntos
COVID-19 , Vacinas , Adulto , COVID-19/epidemiologia , COVID-19/prevenção & controle , Vacinas contra COVID-19 , Criança , Humanos , Pais , SARS-CoV-2 , Vacinação , Hesitação VacinalRESUMO
The response of a large geothermal system to magmatic resurgence was analyzed by a survey of soil gas radon and elemental mercury at 600 sites in the silicic Long Valley Caldera, California. The broad geochemical anomaly over the caldera has superimposed on it a small zone of pronounced radon enrichment and mercury depletion coincident with the surface projection of a postulated dike of rising magma. Soil gas geochemistry studies can complement traditional geophysical and geodetical methods in the evaluation of potential volcanic eruption hazards.
RESUMO
Catastrophic volcanic collapse, without precursory magmatic activity, is characteristic of many volcanic disasters. The extent and locations of hydrothermal discharges at Nevado del Ruiz volcano, Colombia, suggest that at many volcanoes collapse may result from the interactions between hydrothermal fluids and the volcanic edifice. Rock dissolution and hydrothermal mineral alteration, combined with physical triggers such as earth-quakes, can produce volcanic collapse. Hot spring water compositions, residence times, and flow paths through faults were used to model potential collapse at Ruiz. Caldera dimensions, deposits, and alteration mineral volumes are consistent with parameters observed at other volcanoes.
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Eruption plumes of Mount St. Helens, Washington, showed low rates of sulfur dioxide emission, and ash leachates had low ratios of sulfur to chlorine. These data and the nonvesicularity of ash fragments are indicative of only a small eruptive magmatic component. The low amounts of soluble fluorine on the ashes pose no health problems. Violent magmatic activity is possible, and thus continued geochemical monitoring is advised.
RESUMO
The 13 November 1985 eruption of Nevado del Ruiz volcano, in Colombia, released a small volume of pyroclastic material and a disproportionately large volume of volcanic gas. Before the eruption, summit fumarole gases became less water-rich, and the sulfur/chlorine ratio increased. Remote measurements of sulfur dioxide flux after the eruption indicated active degassing at levels associated with eruptive or inter-eruptive stages of other volcanoes. Thermal water analyses revealed increases in magnesium, calcium, and potassium and an increase in the magnesium/chlorine ratio, suggesting that these elements may have been leached from new magma. Ash leachate data showed sulfate and chloride concentrations and ratios that would be expected for the late stages ofa major Plinian eruption. Water from the lahar contained high concentrations of sulfate and had a sulfur/chlorine ratio of 4.67, suggesting that water ejected from the crater lake and turbulent mixing of pyroclasts and glacial ice triggered the lahar. Microprobe analyses of pumice from this eruption and the most recent previous event showed similar mixed andesites. The uniform composition of the pumices and the unusually high ratio of gas to magma suggest that, although a new batch of magma triggered this eruption, the pumice that erupted may actually be old. Large volumes of new magma and glacial ice make the volcano dangerous and should stimulate development of an integrated long-term monitoring program to include Tolima volcano, 25 kilometers to the south.
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SETTING: Bacteriologically confirmed cases of Mycobacterium bovis in the Australian population. OBJECTIVE: To evaluate the DNA fingerprinting techniques commonly used for M. bovis on isolates from humans and determine whether they were useful for determining the origin of human infection. DESIGN: M. bovis strains isolated between 1970 and 1994 were obtained from five Australian Reference Laboratories. Four DNA fingerprinting techniques, comprising Southern hybridisation with three different probes (the insertion sequence [IS]6110, the polymorphic guanine-cytosine-rich sequence [PGRS] and the direct repeat [DR]) and a PCR-based method (spoligotyping) were used. RESULTS: The PGRS, DR and IS6110 RFLP methods identified 32, 22 and 14 different types respectively from the 45 isolates available. Spoligotyping identified 18 different types. When all methods were combined 41 different strains were identified. Clear differences were found between many isolates from Australian-born patients and those from patients born overseas. CONCLUSIONS: The PGRS RFLP method was the most effective method for typing the human strains, but a combination of methods is recommended for maximum sensitivity. Most Australian-born patients that had worked in the meat and livestock industries were infected with strains similar to those that are commonly found in Australian cattle, confirming the occupational risk in these industries. Patients born overseas were typically infected with strains genetically different from those of patients born in Australia. This suggests that patients born overseas identified with M. bovis were presenting with reactivation of infection acquired outside Australia.
Assuntos
Técnicas de Tipagem Bacteriana , Impressões Digitais de DNA , Mycobacterium bovis/classificação , Tuberculose/microbiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Austrália/epidemiologia , Bovinos , Doenças dos Bovinos/microbiologia , Doenças dos Bovinos/transmissão , DNA Bacteriano/análise , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mycobacterium bovis/genética , Polimorfismo de Fragmento de Restrição , Sensibilidade e Especificidade , Tuberculose/epidemiologia , Tuberculose/transmissão , Tuberculose/veterináriaRESUMO
Green tea possesses significant anticancer activity in numerous experimental animal models, including demonstrated protection against aryl hydrocarbon induced cancers. The aryl hydrocarbon receptor (AhR) mediates the transcriptional activation of CYP1A1 and CYP1A2. In the present study, we investigated the effects of commercially available green tea extracts (GTEs) and individual tea catechins on the function of the AhR and on CYP1A gene expression in human hepatoma HepG2 cells and primary cultures of human hepatocytes. GTEs inhibited the transcription of a human CYP1A1 promoter-driven reporter gene induced by the AhR ligand 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD) in a concentration-dependent manner and inhibited the induced accumulation of both CYP1A1 and CYP1A2 mRNAs. GTEs blocked TCDD-induced binding of the AhR to DNA in HepG2 cells and in vitro in isolated hepatic cytosol. To determine if the observed effects were due to a single green tea component, we examined the four major catechins present in GTEs. Only (-)-epigallocatechin gallate (EGCG), the most abundant catechin in green tea, was able to inhibit TCDD-induced binding of the AhR to DNA and subsequent CYP1A transcription, however EGCG alone was less effective than GTEs. We next examined GTEs and catechins for AhR agonist activity. GTEs caused a concentration-dependent increase in CYP1A1-promoter driven reporter gene activity and caused accumulation of CYP1A1 mRNA and protein, but we found that individual catechins were unable to induce the expression of CYP1A1. Our results demonstrate that GTEs as a whole exert mixed agonist/antagonist activity on the AhR, while EGCG functions as a strict AhR antagonist. Therefore, modulation of human CYP1A expression by green tea extracts can not be attributed to the action of a single tea catechin, but rather is due to the effects of a complex mixture. These findings may be useful in future studies concerning green tea as a cancer preventive agent.
Assuntos
Catequina/análogos & derivados , Catequina/farmacologia , Citocromo P-450 CYP1A1/genética , Expressão Gênica/efeitos dos fármacos , Extratos Vegetais/farmacologia , Chá/química , Animais , Carcinoma Hepatocelular/enzimologia , DNA/metabolismo , Cobaias , Humanos , Fígado/enzimologia , Neoplasias Hepáticas/enzimologia , Masculino , Camundongos , Dibenzodioxinas Policloradas/farmacologia , RNA Mensageiro/metabolismo , Receptores de Hidrocarboneto Arílico/efeitos dos fármacos , Receptores de Hidrocarboneto Arílico/fisiologia , Células Tumorais CultivadasRESUMO
Tuberculosis was diagnosed in an adult female hyrax (Procavia capensis) imported from South Africa and held in a captive colony at the Perth Zoo. An organism similar to Mycobacterium microti was isolated from the lung of this animal and the lung of an adult male hyrax in the colony. The organism was not pathogenic to rabbits or guinea pigs. Protein profiles and RFLP patterns using the probes IS6110 and pTBN12 showed both hyrax isolates were identical. These isolates were similar to a M. tuberculosis complex strain isolated from dassies (hyrax) in the late 1950s in South Africa and to M. microti, but appeared to be more closely related to the "dassie bacillus". It is likely that at least one of the hyrax was infected at the time of collection in South Africa. The finding of tuberculosis in these imported animals highlights concern over the lack of suitable tests for the detection of tuberculosis in unusual animal species such as these, and the problems that can arise as a result of the importation of infected animals.
Assuntos
Procaviídeos , Mycobacterium tuberculosis/isolamento & purificação , Tuberculose/veterinária , Animais , Animais de Zoológico/microbiologia , Austrália , Análise por Conglomerados , DNA Bacteriano/genética , Feminino , Variação Genética , Cobaias , Masculino , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/patogenicidade , Polimorfismo de Fragmento de Restrição , Coelhos , África do Sul , Tuberculose/diagnóstico , Tuberculose/microbiologia , VirulênciaRESUMO
Typing of M. bovis isolates for epidemiological purposes is possible using restriction endonuclease analysis (REA). However, the DNA fragment patterns obtained are complex and difficult to analyse due to the large number of bands produced. In an attempt to develop a less complicated typing scheme two DNA probes were used in hybridization studies to detect restriction fragment length polymorphisms (RFLP) in M. bovis. An oligonucleotide probe which matches part of the insertion sequence IS6110 produced few bands and failed to discriminate between bovine isolates of M. bovis. A probe prepared from a highly repeated DNA sequence, cloned from M. tuberculosis when used on southern blots of AluI digested M. bovis DNA, resulted in a discriminating typing scheme which was easier to perform and analyse than the REA. The RFLP typing scheme identified 27 different strains from a total of 36 isolates of M. bovis and 7 reference strains from the M. tuberculosis complex. Using REA, 24 types were identified using BclI and PvuII digests and 23 different types using BstEII digests. When results of all 3 enzyme digests were combined, the REA identified 27 types from the same strains. Ten isolates of M. bovis from 5 properties involved in an outbreak of bovine tuberculosis were all identified as the same type with both techniques.
Assuntos
Técnicas de Tipagem Bacteriana/veterinária , DNA Bacteriano/genética , Mycobacterium bovis/classificação , Mycobacterium tuberculosis/genética , Sequências Repetitivas de Ácido Nucleico/genética , Tuberculose Bovina/microbiologia , Animais , Animais Selvagens/microbiologia , Austrália/epidemiologia , Sequência de Bases , Búfalos , Bovinos , Enzimas de Restrição do DNA , Humanos , Dados de Sequência Molecular , Mycobacterium bovis/genética , Sondas de Oligonucleotídeos , Gambás , Polimorfismo de Fragmento de Restrição , Proibitinas , Focas Verdadeiras , Suínos , Tuberculose Bovina/epidemiologiaRESUMO
Thirty-five crossbred wethers were used to determine the concentrations of alpha-tocopherol in serum and tissues after oral supplementation of six different vitamin E product forms. Five wethers were assigned to each of the following treatments: 1) control, no supplemental vitamin E (C), 2) emulsifiable DL-alpha-tocopheryl acetate-dry (Rovimix E-50% SD), 3) nonemulsifiable DL-alpha-tocopheryl acetate-dry (Rovimix E-50% Ads), 4) emulsifiable DL-alpha-tocopheryl acetate-liquid (Rovimix E-40% Dispersible Liquid Concentrate [DLC]); 5) emulsifiable DL-alpha-tocopherol-liquid (Hoffmann-La Roche, E-40% DLC alcohol), 6) micellized DL-alpha-tocopheryl acetate-liquid (Bioglan, Inc., E-20%); and 7) micellized DL-alpha-tocopherol-liquid (Bioglan, Inc., E-20%). Animals were supplemented daily with 1,000 IU of their respective vitamin E sources for 56 d. Blood samples were collected daily from d 0 to 7 and weekly until d 56. Animals were subsequently killed by exsanguination after stunning and eight different tissues were collected for alpha-tocopherol analysis. There were effects of day, treatment, and day x treatment interaction on serum alpha-tocopherol. All supplemented groups were higher in serum alpha-tocopherol concentration than were the C wethers. The emulsifiable vitamin E alcohol liquid product form (Treatment 5) yielded higher (P less than .01) serum alpha-tocopherol concentration than the emulsifiable acetate liquid product (Treatment 4). Sheep on Treatment 5 reached maximum concentration on d 1, sheep on Treatment 6 on d 2, and the sheep on the remaining Treatments by d 3. Blood sera alpha-tocopherol concentrations stabilized by d 6 in all supplemented groups.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Ovinos/metabolismo , Vitamina E/farmacocinética , alfa-Tocoferol/análogos & derivados , Administração Oral , Ração Animal , Animais , Disponibilidade Biológica , Emulsões , Alimentos Fortificados , Fígado/metabolismo , Masculino , Micelas , Miocárdio/metabolismo , Pâncreas/metabolismo , Tocoferóis , Vitamina E/administração & dosagem , Vitamina E/análogos & derivados , Vitamina E/sangueRESUMO
Twenty-six pregnant ewe lambs were used to study the effect of four treatment (T 1 to 4) levels of DL-alpha-tocopheryl acetate (0, 15, 30, and 60 IU.lamb-1.d-1) supplemented 28 d prepartum through 28 d postpartum on placental and mammary gland transfer of alpha-tocopherol. Blood samples were first obtained on d 28 prepartum and thereafter with milk samples at designated intervals up to 28 d postpartum for alpha-tocopherol analyses. Similarly, blood samples were obtained from neonatal lambs on d 1 before suckling and on d 3, 14, and 28 postpartum. Ewe lamb serum tocopherol concentrations averaged .66 micrograms/mL before T administration; 28 d later averages were .93, 1.94, 2.63, and 4.07 micrograms/mL (linear, P < .05) for T 1 to 4, respectively. Supplemental vitamin E had no effect (P > .05) on serum alpha-tocopherol of neonatal lambs, indicating inefficient placental transfer. By d 3, lamb serum tocopherol increased to 1.41, 1.84, 2.43, and 4.46 micrograms/mL (linear, P < .05) for T 1 to 4 following consumption of colostrum and declined to .46, .74, 1.10, and 1.68 micrograms/mL (linear, P < .05) by d 28. On d 1 there was a linear (P < .05) treatment effect on tocopherol in colostrum, with a low concentration of 3.30 micrograms/mL for the control (T 1) and a high of 9.55 micrograms/mL for T 4.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Glândulas Mamárias Animais/metabolismo , Placenta/metabolismo , Ovinos/metabolismo , Vitamina E/análogos & derivados , Vitamina E/metabolismo , alfa-Tocoferol/análogos & derivados , Análise de Variância , Ração Animal , Animais , Antioxidantes/administração & dosagem , Antioxidantes/farmacologia , Colostro/química , Relação Dose-Resposta a Droga , Feminino , Alimentos Fortificados , Glândulas Mamárias Animais/efeitos dos fármacos , Leite/metabolismo , Placenta/efeitos dos fármacos , Período Pós-Parto/efeitos dos fármacos , Período Pós-Parto/metabolismo , Gravidez , Distribuição Aleatória , Tocoferóis , Vitamina E/administração & dosagem , Vitamina E/sangue , Vitamina E/farmacologiaRESUMO
The effects of supplemental dietary vitamin E (as DL-alpha-tocopheryl acetate; 0, 15, 30, and 60 IU/d) on serum, platelet, and muscle tocopherol and lipid (cholesterol and triglycerides) concentrations in 32 sheep were investigated in a 60-d trial. Serum, platelet, and muscle alpha-tocopherol concentrations increased linearly (P < .05) with treatment. Platelet tocopherol concentrations were more sensitive to vitamin E intake than either serum or muscle tocopherol. There were no effects on serum lipid concentrations. There were low correlations (P > .05) between serum or platelet tocopherol and either cholesterol or triglycerides or the sum of the two lipid fractions. Correlations between serum or platelet tocopherol and muscle tocopherol were also low (P > .05). Although platelet tocopherol was more sensitive to vitamin E intake than serum tocopherol, serum tocopherol concentrations can be reliably used to estimate vitamin E status. Expressing serum tocopherol relative to blood lipids did not improve the relationship between serum tocopherol and vitamin E intake.
Assuntos
Estado Nutricional , Ovinos/fisiologia , Vitamina E/normas , Animais , Plaquetas/química , Colesterol/sangue , Cruzamentos Genéticos , Alimentos Fortificados , Músculo Esquelético/química , Avaliação Nutricional , Distribuição Aleatória , Ovinos/sangue , Triglicerídeos/sangue , Vitamina E/análise , Vitamina E/sangueRESUMO
Supplementary alpha-tocopheryl acetate (vitamin E) was fed to provide none (E0), 2,000 IU/d (E2000), 5.8 IU/kg live weight (E5.8), or 8.6 IU/kg live weight (E8.6) to steers that were individually fed mainly a corn diet. Three steers were placed on each of 10 treatments: E0, E2000, E5.8, E5.8 to d 126 then E0 to d 266, E0 to d 126 then E5.8 to d 266, E8.6, grazing followed by either E0 or E8.6 all with Holstein steers; and E0 and E2000 with crossbred beef steers. During the last 100 d, vitamin E consumption (International Units/day) averaged 96 for E0, 1,840 for E2000, 2,520 for E5.8, and 3,610 for E8.6. Concentrations of alpha-tocopherol in plasma and in liver and longissimus lumborum biopsy samples obtained every 42 d were elevated (P < .01) by vitamin E supplementation. Tissue saturation was approached at these vitamin E intakes causing similar incorporation of alpha-tocopherol with both per day and per BW supplementation strategies. Maximum accretion or depletion of alpha-tocopherol in plasma and liver occurred before 42 d, but accretion required 120 d and depletion required 180 d in longissimus lumborum. Vitamin E supplementation elevated (P < .01) concentrations of alpha-tocopherol in liver, lung, subcutaneous fat, omental fat, perirenal fat, kidney, diaphragm, spinal cord, longissimus lumborum, and plasma at slaughter with maximum accretion achieved (P < .01) in lung, subcutaneous fat, kidney, diaphragm, and spinal cord. Depletion was not achieved in longissimus lumborum and spinal cord (P < .01), subcutaneous fat (P < .06), and perirenal fat (P < .08) within 140 d. Vitamin E inhibited (P < .01) oxidation at the surface and center of longissimus lumborum steaks displayed for 19 d. Lipid oxidation occurred throughout E0 steaks, but metmyoglobin accumulation occurred more rapidly (P < .01) on the surface than in the center. Myoglobin and lipid oxidation were not concurrent events. Supplementation with vitamin E increased (P < .01) alpha-tocopherol concentrations in longissimus lumborum fractions (mitochondria, microsome, cytoplasm, connective, and remainder) but, except for connective tissue, the proportional distribution of total longissimus lumborum alpha-tocopherol was not affected (P > .1) by vitamin E supplementation. Vitamin E supplementation for at least 44 d at 1,300 IU/d is expected to incorporate adequate amounts of alpha-tocopherol into muscle (3.3 micrograms/g for longissimus lumborum) to produce beef with extended color and lipid stability.
Assuntos
Bovinos/metabolismo , Metabolismo dos Lipídeos , Mioglobina/metabolismo , Vitamina E/farmacocinética , Tecido Adiposo/metabolismo , Ração Animal , Animais , Alimentos Fortificados , Fígado/metabolismo , Masculino , Carne/normas , Metamioglobina/biossíntese , Músculos/metabolismo , Oxirredução , Pigmentação , Análise de Regressão , Distribuição Tecidual , Vitamina E/administração & dosagem , Vitamina E/sangueRESUMO
Pigment and lipid oxidations were investigated in longissimus lumborum (LL), semimembranosus (SM), and gluteus medius (GM) from Holstein steers fed four doses of vitamin E (64 [control], 295, 550, or 2,173 IU/d) for two durations (42 or 126d). Vitamin E dose did not affect (P = .30) carcass quality or yield characteristics. The LL was stored in vacuum packages at 4 degrees C for 14, 28, and 56 d, and GM and SM were stored for 14 d. Increments of dose and duration of vitamin E supplementation increased (P < .001) alpha-tocopherol concentration in blood plasma and in these muscles. During simulated retail display, accumulations of metmyoglobin (METMB) and thiobarbituric acid reactive substances (TBARS) were greater (P < .01) in beef from control than in beef from supplemented steers. In cubic models, muscle alpha-tocopherol accounted for 79% of the variation in TBARS and 66% of the variation in METMB. Color display life, calculated by the METMB threshold method, revealed fewer dose and duration effects of vitamin E than were evident following analysis of variance of the METMB responses. Across durations and muscles, color display-life of fresh beef calculated by the METMB threshold method was extended (P < .05) .9 to 1.8 d by vitamin E supplementation (P < .05). Storage for 28 or 56 d caused only a slight decline (P < .001) in LL alpha-tocopherol concentration but diminished (P < .05) vitamin E effects on color display-life. Although the ranking of alpha-tocopherol accumulation was GM > SM > LL, the color display-life ranking of these muscles across vitamin E treatments was LL > SM > GM.
Assuntos
Malondialdeído/análise , Carne/normas , Músculo Esquelético/anatomia & histologia , Músculo Esquelético/química , Pigmentação/efeitos dos fármacos , Vitamina E/farmacologia , Envelhecimento/fisiologia , Animais , Bovinos , Relação Dose-Resposta a Droga , Tecnologia de Alimentos , Alimentos Fortificados , Masculino , Malondialdeído/metabolismo , Metamioglobina/análise , Metamioglobina/metabolismo , Músculo Esquelético/metabolismo , Mioglobina/análise , Mioglobina/metabolismo , Oxirredução , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo , Fatores de Tempo , Vitamina E/administração & dosagem , Vitamina E/análiseRESUMO
An experiment was conducted to evaluate the capabilities of dual photon absorptiometry (PA), radiographic photometry (RP), and ultrasound (U) to estimate bone mineral content (BMC) and bone strength of a group of bovine third metacarpals (McIII). Metacarpals were chosen for evaluating BMC and bone strength because of their accessibility and susceptibility to biomechanical stress. The right and left McIII of 14 Angus heifers (24 to 32 mo of age) were collected at slaughter and all soft tissues (including periosteum) were removed. The BMC was estimated at both the midpoint and 3 cm proximal to the midpoint on the McIII diaphysis. Metacarpals then were tested by three-point bending to determine breaking load (BL) and breaking strength (BS). Bones were reassembled and two 2-cm sections were removed, one at the midpoint and one 1 cm proximal to the midpoint section. Sections then were ashed and ash content was expressed as grams per 2-cm slice and defined as BMC. Correlation coefficients (r) between BMC vs PA, RP, and U were .908 (P less than .0001), .967 (P less than .0001), and .565 (P less than .0001), respectively; r values between BS vs PA, RP, and U were .406 (P less than .05), .429 (P less than .05), and .499 (P less than .01), respectively, and r values between BL vs PA, RP, and U were .870 (P less than .0001), .865 (P less than .0001), and .588 (P less than .001), respectively. These data indicate that noninvasive techniques are useful in predicting BMC and BL in the bovine.
Assuntos
Densidade Óssea , Osso e Ossos/fisiologia , Bovinos/fisiologia , Absorciometria de Fóton , Animais , Osso e Ossos/anatomia & histologia , Osso e Ossos/diagnóstico por imagem , Feminino , Metacarpo/anatomia & histologia , Metacarpo/diagnóstico por imagem , Metacarpo/fisiologia , Fotometria , Distribuição Aleatória , Estresse Mecânico , UltrassonografiaRESUMO
Fourteen Angus heifers (210 +/- 6 kg initial BW) were allotted randomly to either a low P (LP: .12% P, DM basis) or an adequate P (AP: .20% P, DM basis) diet fed for 14 to 16 mo under drylot conditions on concrete floors to determine the influence of dietary P on chemical, physical, and mechanical properties of bone. Three weeks postpartum, after 14 to 16 mo on their diets, heifers were slaughtered and the right and left third metacarpals (McIII) were excised; soft tissue was removed and metacarpals were frozen in .9% saline. Metacarpals were subjected to a three-point flexure test using an Instron Testing Machine with a crossload speed of 50 mm/min to determine mechanical properties. Broken McIII were reassembled and a 2-cm section was removed at point of loading for determination of chemical and physical properties. Breaking load (BL) was greater (P less than .05) for McIII from the AP than for those from LP heifers (1,348 vs 1,179 kg). Breaking strength (BS) was greater (P less than .05) for AP than for LP heifers (202.5 vs 189.2 MPa). Animals receiving AP diets had greater (P less than .01) bone mineral content (12.6 vs 11.2 g/2-cm slice) and percentage of bone ash (68.0 vs 67.2%) than did LP animals. No differences (P greater than .10) were observed between treatment groups in Ca, P, or Mg percentage in bone ash. Circular, elliptical, radiographic, and planimeter area indices all were greater (P less than .05) in AP than in LP animals (1,048, 729, 1,069, and 570 vs 932, 660, 957, and 523 mm2, respectively). These data indicate that mechanical properties of bovine third metacarpals are sensitive to dietary P and reflect P status in the bovine. Mineral content of bone was highly correlated with its mechanical and physical properties.
Assuntos
Densidade Óssea , Desenvolvimento Ósseo , Osso e Ossos/química , Bovinos/fisiologia , Fósforo/administração & dosagem , Animais , Osso e Ossos/fisiologia , Bovinos/anatomia & histologia , Feminino , Metacarpo/química , Metacarpo/fisiologiaRESUMO
Three experiments were conducted to examine the effects of vitamin E supplementation on feedlot cattle. Vitamin E supplementation did not affect feedlot performance or carcass characteristics of cattle fed a high-concentrate diet (P greater than .1). The major finding was the effectiveness of vitamin E in extending the color stability of displayed beef (P less than .01). Color stability during display of longissimus lumborum steaks from cattle supplemented with 300 IU/d for 266 d, 1,140 IU/d for 67 d, or 1,200 IU/d for 38 d was extended by 2.5 to 4.8 d. Gluteus medius steaks had an extended color display life of 1.6 to 3.8 d. The accumulation of lipid oxidation products, but not aerobic microbes, associated with displayed longissimus lumborum was suppressed for muscle from vitamin E-supplemented steers. Taste panelists detected no difference among longissimus lumborum steaks from control and vitamin E-supplemented steers but found (P less than .01) steaks aged for 21 d to be more tender than steaks aged for 7 d. Supplementing cattle with vitamin E should reduce economic losses associated with discolored beef during retail display.
Assuntos
Bovinos/crescimento & desenvolvimento , Carne/normas , Vitamina E/análogos & derivados , alfa-Tocoferol/análogos & derivados , Tecido Adiposo/efeitos dos fármacos , Tecido Adiposo/crescimento & desenvolvimento , Administração Oral , Ração Animal , Animais , Composição Corporal/efeitos dos fármacos , Cruzamento , Bovinos/genética , Cruzamentos Genéticos , Metabolismo dos Lipídeos , Masculino , Metamioglobina/metabolismo , Desenvolvimento Muscular , Músculos/efeitos dos fármacos , Mioglobina/metabolismo , Oxirredução , Pigmentação , Tocoferóis , Vitamina E/administração & dosagem , Vitamina E/farmacologiaRESUMO
Forty-three crossbred wethers weighing 35 to 60 kg were used to investigate the effect of a single i.m. injection of DL-alpha-tocopherol (DL-alpha-ol). Animals were offered 1 kg/d of a basal diet containing 25 ppm of vitamin E. Lambs were randomly assigned to one of five DL-alpha-ol injection treatments as follows: 1) control (placebo, 0 IU), 2) 125 IU, 3) 250 IU, 4) 500 IU, or 5) 1,000 IU. Blood samples were taken via jugular venipuncture on d 1 before treatment administration and thereafter at designated intervals up to 360 h postinjection. The i.m. injections of DL-alpha-ol irrespective of dose increased serum alpha-tocopherol. Results showed a dose x time interaction (P less than .0001) across all treatments. Serum alpha-tocopherol increased rapidly to maximum concentration during the first 8 to 12 h for all non-zero treatments, followed by a rapid decline to pretreatment values. The mean serum alpha-tocopherol concentration at 0 h was .69 microgram/mL. Estimated peak serum alpha-tocopherol concentrations +/- SE were 6.68 +/- 1.04, 9.62 +/- 1.04, 21.66 +/- 2.37, and 50.75 +/- 7.05 micrograms/mL for Treatments 2 through 5, respectively. Results showed a quadratic dose effect (P less than .0003) on maximum response with apparently no effect on time taken to reach this peak. There was also a quadratic dose effect (P less than .0001) on the area under the concentration-time curve. The time taken for serum alpha-tocopherol to return to pretreatment levels increased with dose (56, 64, 67, and 74 h, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Ovinos/metabolismo , Vitamina E/farmacocinética , Análise de Variância , Animais , Relação Dose-Resposta a Droga , Injeções Intramusculares/veterinária , Modelos Lineares , Masculino , Distribuição Aleatória , Vitamina E/administração & dosagem , Vitamina E/sangueRESUMO
Effects of four dietary levels of DL-alpha-tocopheryl acetate (0, 500, 1,500, and 3,000 IU.animal-1.d-1) on serum, red blood cell (RBC), and tissue alpha-tocopherol concentrations were investigated in 32 yearling cattle during an 84-d trial. Supplemental vitamin E was fed for 28 d, withdrawn for 28 d, and then resumed for another 28 d. Blood was collected on d 1 before treatment administration, d 3, and biweekly thereafter. Serum alpha-tocopherol increased rapidly from pretreatment values (1.8 micrograms/mL) with linear (P < .05) treatment effects on d 3 and 14 and cubic treatment effects on d 28. Upon withdrawal of vitamin E supplementation, serum tocopherol concentrations declined and again increased rapidly and linearly by d 84 after supplementation was resumed. Concentration of alpha-tocopherol in RBC did not respond appreciably to supplemental vitamin E. There were no vitamin E treatment effects on blood lipid fractions (cholesterol and triglycerides). When serum tocopherol was expressed relative to the sum of cholesterol and triglycerides, response to vitamin E intake followed similar trends as serum alpha-tocopherol. The relationship between serum alpha-tocopherol concentrations or serum tocopherol:cholesterol plus triglycerides ratio and vitamin E intake was linear (P < .05) for d 14, 28, and 84 and linear with liver for d 84. Serum and liver tocopherol reflected vitamin E intake and can be used reliably to estimate vitamin E status in young cattle.