bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermogenic drugs for the treatment of obesity: sympathetic stimulants in animal models
Authors: Dulloo A. G. , Miller D. S. 
Published: June 2005

1. Thirty-three drugs known to stimulate the sympathetic nervous system have been screened for thermogenic properties. The results presented are for seven of them.2. The drugs were tested in five animal models of obesity (genetic (mice and rats), hypothalamic (mice) and dietary (mice and rats)) as well asin leanmice. Energy-balance studies were undertaken using thecomparative-carcass technique as well as by measurement of daily oxygen consumption.3. All seven drugs in obese animals tended to reduce body-weight and fat without loss of body protein: they acted by increasing metabolic rate without increasing food intake. They were much less effective in lean animals. These findings lend support to the concept that obesity is due to a diminished activity of the sympathetic nervous system.4. Differences in the effectiveness of the drugs are discussed in relation to differences between the animal models of obesity. Ephedrine and tranylcypromine were found to be the most effective drugs in this series of experiments and a prima facie case is made for human clinical trials.
Does guar gum improve post-prandial hyperglycaemia in humans by reducing small intestinal contact area?
Authors: Blackburn N. A. , Holgate A. M. , Read N. W. 
Published: June 2005

1. The possibility that viscous polysaccharides, such as guar gum, could lower post-prandial blood glucose levels in part by restricting carbohydrate solutions to a smaller area of small intestine was investigated in twenty healthy human volunteers.2. Addition of guar gum (22.5 g/l) delayed the mouth-to-caecum transit time of a hypotonic lactulose drink, but did not affect gastric emptying.3. When a 250 ml solution containing 50 g glucose was confined to a 550 mm length of intestine by an occluding balloon attached to an intestinal tube, maximum blood glucose response was significantly reduced (P < 0.05) though only by 0.9 mmol/l.4. Addition of guar gum (36 g/l) had no effect on the distribution of a radio-labelled glucose drink (250 ml; 200 g glucose/l) in the small intestine, monitored using a gamma camera, although it significantly delayed gastric emptying (t½ (min): guar gum v. control 115 (SE 15) v. 73 (SE 8)).5. Reduced contact area is unlikely to be one of the mechanisms by which guar gum improves glucose tolerance.
Zinc metabolism in pregnant and lactating rats and the effect of varying iron: Zn in the diet
Authors: Fairweather-Tait Susan J. , Wright A. J. A. , Williams Christine M. 
Published: June 2005

1. Pregnant rats were given control (46 mg iron/kg, 61 mg zinc/kg), low-Zn (6.9 mg Zn/kg) or low-Zn plus Fe (168 mg Fe/kg) diets from day 1 of pregnancy. The animals were allowed to give birth and parturition times recorded. Exactly 24 h after the end of parturition the pups were killed and analysed for water, fat, protein, Fe and Zn contents and the mothers' haemoglobin (Hb) and packed cell volume (PCV) were measured.2. There were no differences in weight gain or food intakes throughout pregnancy. Parturition times were similar (mean time 123 (SE 15) min) and there were no differences in the number of pups born. Protein, water and fat contents of the pups were similar but the low-Zn Fe-supplemented group had higher pup Fe than the low-Zn unsupplemented group, and the control group had higher pup Zn than both the low-Zn groups. The low-Zn groups had a greater incidence of haemorrhaged or deformed pups, or both, than the controls.3. Pregnant rats were given diets of adequate Zn level (40 mg/kg) but with varying Fe:Zn (0.8, 1.7, 2.9, 3.7). Zn retention from the diet was measured using65Zn as an extrinsic label on days 3, 10 and 17 of pregnancy with a whole-body gamma-counter. A group of non-pregnant rats was also included as controls. The65Zn content of mothers and pups was measured 24–48 h after birth and at 14, 21 and 24 d of age.4. In all groups Zn retention was highest from the first meal, fell in the second meal and then rose in the third meal of the pregnant but not the non-pregnant rats. There were no differences between the groups given diets of varying Fe:Zn level. Approximately 25% of the65Zn was transferred from the mothers to the pups by the time they were 48 h old, and a further 17% during the first 14 d of lactation. The pup65Zn content did not significantly increase after the first 20 d of lactation but the maternal65Zn level continued to fall gradually.
Growth and development of rats artificially reared on different milk-substitutes
Authors: Smart J. L. , Stephens D. N. , Tonkiss J. , Auestad N. S. , Edmond J. 
Published: June 2005

1. Rat pups were artificially reared (AR) from postnatal day 4 or 5 till day 20 or 21, by fitting them with gastric cannulas through which milk-substitutes could be infused automatically.2. Three milk-substitutes were compared: milk M, the usual diet for AR studies, which was somewhat low in protein and very high in carbohydrate; milk A, which resembled rats' milk much more closely in composition; and milk isoM, which was based on the high-energy milk M but was made isoenergetic with milk A. Pups given these diets were termet ARM, ARA and ARisoM respectively. Siblings of the AR rats were left with their mothers to form a mother-reared (MR) control group. Rats were autopsied at 20 or 21 d.3. Growth in body-weight of all groups of AR pups lagged behind that of their MR siblings for about the first week of AR, but the ARM group showed complete catch-up and the ARA group partial catch-up in body-weight during the second week. ARisoM rats were growth-retarded throughout.4. Inspection of organ weights expressed relative to body-weight revealed disturbances of organ growth in all AR groups compared with MR animals. ARM rats showed excessive epididymal fat pad and liver weights, but deficits in gastrocnemius muscle, heart and adrenal weights. In contrast, ARA rats usually displayed increased spleen and stomach weights, but lower weight of interscapular brown adipose tissue. ARisoM rats had high brain, liver and stomach weights and low muscle and spleen weights relative to body-weight. All AR groups had elongated small intestines.5. Hence the patterns of abnormal organ growth differed between groups. Those shown by the ARM and ARisoM groups seemed the more seriously abnormal. The diet approximating the composition of rats' milk (milk A) appears, as intended, to be an improved milk-substitute.
Nutritional availability of amino acids from protein cross-linked to protect against degradation in the rumen
Authors: Ashes John R. , Mangan Jim L. , Sidhu Gurcharn S. 
Published: June 2005

1. Casein was labelled with pairs of radioactive amino acids, lysine, tyrosine and leucine, one with I4C and the other with 3H, by jugular infusion into lactating goats followed by isolation of the double-labelled casein from the milk. Total milk protein was similarly labelled by jugular infusion of [35S]cystine. U-14C-labelled fraction- 1 leaf protein was isolated from lucerne (Medicago sativa) grown in an atmosphere of 14C022. The proteins were treated withdifferent levels(333 and667 mmol/kgprotein) offormaldehyde, glutaraldehyde and glyoxal.3. Absorption from the small intestine was measured in sheep with fistulas in the abomasum and terminal ileum, using Cr-EDTA as the digesta flow marker, by introducing radioactive casein into the abomasum.4. Lysine, tyrosine and cystine became increasingly unavailable for absorption from the small intestine of sheep with increasing levels of aldehyde. At the lower level (333 mmol/kg) the proportions of the amino acids that were unavailable were 0.192, 0.051 and 0.123 respectively. At the higher level of formaldehyde (667 mmol/kg) the corresponding values were 0.335, 0.201 and 0.432 respectively. Leucine was not made unavailable with formaldehyde.5. The proportions of lysine, tyrosine and leucine that were unavailable were higher, on a molar basis, after treatment of the proteins with the dialdehydes glutaraldehyde and glyoxal than after treatment with formaldehyde. However, the extent of protein protection provided by the dialdehydes in the rumen, measured using an in vitro procedure, was lower.
Microbial protein synthesis in cattle given roughage–concentrate and all-concentrate diets: the use of 2,6-diaminopimelic acid, 2-aminoethylphosphonic acid and 35S as markers
Authors: Whitelaw F. G. , Eadie J. Margaret , Bruce L. A. , Shand W. J. 
Published: June 2005

1. Three steers, each fitted with a rumen cannula and a re-entrant cannula in the proximal duodenum, were offered diets consisting of a barley-based concentrate and chopped hay at a daily intake of 61 g/kg live weight0-75 given in three. equal meals. The ratio, concentrate: hay was changed from 50: 50 to 90: 10 and then to 100: O in successive periods of 12–18 weeks and the flow and composition of digesta at the duodenum was measured over 48-h periods on each dietary treatment.2. Samples of bacteria and protozoa were separated from rumen contents and the proportions of bacterial and protozoal nitrogen (N) in duodenal digesta were estimated using 2, ddiaminopimelic acid (DAPA) and 2- aminoethylphosphonic acid (AEP) as markers. On separate occasions, radioactive sulphur (35S) was infused into the rumen for 48 h and digesta collected over the final 24 h; the specific radioactivity of S in microbial and digesta fractions was used to estimate the proportions of microbial N.3. 35S gave reproducible and apparently reliable estimates of microbial protein formation: the proportion of microbial N in digesta was significantly higher (P < 0.05) for the 50:50 diet than for the other treatments but the energetic efficiency of microbial protein formation did not differ significantly between diets.4. Estimatesof bacterial N based on DAPA concentrations were highly variable and frequently impossibly high. It is suggested that many of the anomalous values were the result of non-representative sampling of the rumen microbial population and that this is particularly likely to occur when conditions within the rumen are unstable. AEP was found to be unsuitable as a marker for rumen protozoa as considerable concentrations of this substance were found also in rumen bacteria.
Methane formation in faunated and ciliate-free cattle and its relationship with rumen volatile fatty acid proportions
Authors: Whitelaw F. G. , Eadie J. Margaret , Bruce L. A. , Shand W. J. 
Published: June 2005

1. Twelve steers fitted with rumen cannulas were used in three separate experiments to investigate the effects of the presence or absence of rumen ciliate protozoa on methane production. The diet consisted of 850 g barley and 150 g protein supplement/kg, and was given in three feeds daily at a restricted level of 61 g/kg live weight0.75. Animals were defaunated initially by allowingad lib. consumption of this diet and were then maintained ciliate-free by isolation or were faunated by inoculation with a mixed ciliate suspension. Samples of rumen fluid were taken routinely for the assessment of microbial populations and for volatile fatty acid (VFA) analysis and energy and nitrogen balances and digestibility measurements were made at intervals while animals were confined in respiration chambers.2. In each experiment the rumen VFA proportions changed from a high-propionate pattern under ciliate-free conditions to a low-propionate, high-butyrate pattern in the presence of ciliates: differences between treatments were highly significant (P < 0.001). There were also marked differences between treatments in CH, production but a reliable comparison was possible only in Expt 3, in which CH4was significantly higher (P < 0.001) in the presence of a rumen ciliate population. In Expt 3 the increased loss of energy as CH4in the faunated animals amounted to 44 MJ/100 MJ energy intake.3. Stoichiometric estimates of CH4production derived from the observed VFA proportions showed good agreement with CH4production as measured in respiration chambers. On average, the stoichiometric CH4values overestimated CH4production by a factor of 1.08.4. Highly significant linear relationships (P < 0.001) were observed between the molar proportion of each major VFA and the quantity of CH4produced: the proportion of propionic acid was inversely related to CH4and showed the lowest residual standard deviation of all the relationships examined.5. The losses of energy in faeces and urine did not differ between treatments hence the increased loss of energy as CH4in the faunated animals resulted in a significant reduction in the metabolizability of the diet from 0.73 to 0.69 (P < 0.05). No significant differences were detected between treatments in heat production, apparent digestibility coefficients or N balance.6. It is suggested that the rumen ciliates, by modifying the rumen VFA proportions, are directly responsible for the increased CH4production in faunated animals.
Glucose turnover and recycling in unrestrained and unanesthetized 48-h-old fasting or post-absorptive newborn pigs
Authors: Pégorier Jean-Paul , Duée Pierre-Henri , Nunes Carlo Simoes , Peret Jean , Girard J. 
Published: June 2005

1. The metabolism of glucose has been studied in 48-h-old unanesthetized fasting and post-absorptive sucking piglets.2. Both [6-3H]- and [U-14CJglucose were administered either by a single injection method or by a primed infusion technique. The rates of glucose turnover and recycling were estimated under steady-state conditions.3. The rates of glucose turnover and recycling in 48-h-old fasting or post-absorptive piglets were not statistically different when measured using the single injection technique or the printed infusion method.4. The mean (with SE) rate of glucose turnover was 65.8 (2.5) in post-absorptive and 31.1 (1–9), μ mol/kg per min in fasted newborn pigs. Glucose utilization was linearly related to blood glucose concentration; regression analysis indicated a y-intercept of 7.2, μ mol/kg per min.5. As tested by arterio-portal differences the gut was not releasing glucose or galactose in 5 h-post-absorptive sucking newborn pigs. Thus, the higher rates of glucose turnover in post-absorptive newborn pigs compared with fasting ones suggest that hepatic glucose production is enhanced in post-ahsorptive sucking piglets.6. The mean (with SE) rates of glucose recycling were four times higher in post-absorptive piglets than in tasting ones, i.e. 14.4 (1.6) and 3.7 (0.5)% of [6-3H] glucose turnover respectively. As liver glycogen was exhausted in 48-h-old sucking piglets, this suggests that hepatic glucose production results from gluconeogenesis.
Response of male and female rats to undernutrition
Authors: Harris Patricia M. , Broadhurst R. B. , Hodgson Diane F. 
Published: June 2005

1. Female Wistar rats (5 and 11 weeks old) were either left intact or ovariectomized. Animals of each age- and treatment-group were either ad lib.-fed or undernourished for 4 weeks.2. The bodies of all animals were analysed for protein and fat and the weights, lipid synthesis rate and lipoprotein lipase (EC 3.1. 1.34) activity of four fat depots were determined.3. The well-nourished ovariectomized animals of both age-groups gained weight more rapidly than the well-nourished intact animals of the same age, but there was no effect of ovariectomy on body composition, lipid synthesis rate or lipoprotein lipase activity in either the well-nourished or the undernourished animals of either age-group.4. There was a greater efficiency of energy utilization found in the ovariectomized animals than in the intact animals regardless of age or nutritional status.
The effect of abomasal infusion of casein on acetate, palmitate and glucose kinetics in cows during early lactation
Authors: Köning Barbara A. , Oldham J. D. , Parker D. S. 
Published: June 2005

1. Four mature Friesian cows were used in a Latin square design experiment to measure the effects of abomasal casein infusion on milk production and the kinetics of glucose, acetate and palmitate in jugular venous blood.2. The basal ration contained 110 g crude protein/kg dry matter and was offered at the rate of 4 kg hay, 3 kg alkali-treated straw cubes plus 9 kg concentrates/d. Treatments were infusion of casein into the abomasum at the rate of 0, 240 or 460 g/d. The experiment started 1 week post partum. Experimental periods lasted 21 d.3. [6-3H]glucose, [9, 10-3H]palmitate and [U-14C]acetate were continuously infused into one jugular vein for measurements of whole-body flux rates.4. The yield of milk protein was increased significantly (P < 0.05) by the first increment of casein infusion, with no further increases.5. Casein infusion had no effect on blood concentrations of glucose, acetate, palmitate or growth hormone. Mean flux rate of glucose increased with each increment of casein. The effect at 460 g/d was higher (P < 0.1) than with no infusion. Flux rates of palmitate and acetate were increased (P< 0.1) by the first increment of casein. The proportion of blood bicarbonate derived from acetate increased (P < 0.05) with the first increment of casein.6. Protein status of cows early in lactation influences the dynamics of glucose and fatty acid metabolism.
Insulin response to glucose and glucose tolerance following feeding in sheep
Authors: Sasaki Y. , Takahashi H. , Aso H. , Hikosaka K. , Hagino A. , Oda S. 
Published: June 2005

1. Sheep offered a roughage diet for 4 h daily were injected intravenously with glucose before and at various times after feeding. The insulin secretory response to glucose and the rate of disappearance of injected glucose were determined.2. While the basal concentration of plasma insulin was unchanged, the base-line plasma glucose concentration tended to decrease during the meal.3. The glucose load brought about an increase in the plasma insulin concentration at each injection, but the insulin response to glucose and the rate of glucose disposal were increased during the meal.4. On varying the time of feeding between 08.00 and 16.00 hours, the increase in the insulin response to glucose and in the rate of glucose disposal always appeared to be related to the giving of food, independent of the time food was offered.5. It is concluded that feeding increases the insulin response to an intravenous glucose load even when the increase in the basal level of plasma insulin on feeding is very modest in sheep given a roughage diet. The increased insulin response and glucose disposal rate following feeding did not appear to be related to diurnal rhythms in insulin secretory activity or glucose metabolism.
Whole body and tissue fractional protein synthesis in the ovine fetusin utero
Authors: Schaefer A. L. , Krishnamurti C. R. 
Published: June 2005

1. Whole-body and tissue fractional protein synthesis rates were determined in chronically-catheterized ovine fetuses at 120–130 d of gestation following an 8 h continuous infusion of L-[U-14C]-or L-[2, 3, 5, 6-3H]tyrosine.2. From the net utilization of tyrosine by the fetus, corrected for apparent oxidation, and tyrosine concentration in the fetal carcass protein, whole-body protein synthesis was estimated to be 63 g/d per kg.3. Following 8 h of infusion of labelled tyrosine the ewes were killed and fetal tissues were removed for the determination of tyrosine specific activity. The fractional rate of protein synthesis (k3) was calculated from the specific activity ratio, protein bound: intracellular free tyrosine. Tissue k, values for the liver, kidney, lungs, brain, skeletal muscle and small intestine were 78, 45, 65, 37, 26 and 93% /d respectively.4. The absolute rate of synthesis was calculated by multiplying the tissue protein content by k2. Muscles, gastrointestinal tract, liver and lungs contributed approximately 20.5, 20.5, 14.4 and 9.4% respectively to whole- body protein synthesis.5. The efficiency of protein synthesis as expressed by the RNA activity was higher in liver, lung and brain followed by kidney, skeletal and cardiac muscle.
Hexose transport and mucosal morphology in the small intestine of the zinc-deficient rat
Authors: Southon Susan , Gee Jennifer M. , Johnson I. T. 
Published: June 2005

1. Immature male Wistar rats were given a zinc-depleted semi-synthetic diet (2 mg Zn/kg diet) for 4 weeks. Control groups received a similar diet containing 60 mg Zn/kg diet, either ad lib. or in amounts matched to the consumption of the Zn-deficient group. Rates of growth and food conversion efficiency were markedly lower in the Zn-deficient group compared to controls.2. The phloridzin-sensitive uptake of galactose and 3-0-methyl glucose by everted jejunal rings from each group was measured over a range of concentrations. Kinetic analysis revealed that the maximum transport rate (Vmax)for the uptake of both sugars was significantly higher in the Zn-deficient group than in the control groups.3. The villi, microdissected from samples of proximal jejunum, were significantly shorter and narrower across the base in the Zn-deficient group than those of the control groups, but were present in greater numbers per unit serosal area.4. The present study shows that Zn deficiency leads to significant morphological changes in rat small intestine, which are accompanied by an increase in the capacity of the tissue to take up sugars across the mucosal membrane.
The physical digestion of perennial ryegrass (Lolium perenne) and white clover (Trifolium repens) in the foregut of sheep
Authors: Moseley G. , Jones J. R. 
Published: June 2005

1. Sheep were fed once daily with 300 or 600 g dried perennial ryegrass (Lolium perenne) or white clover (Trifolium repens). Total rumen contents were sampled once daily at various intervals up to 24 h after feeding for 6 d.2. Total weight of fresh rumen contents and dry matter (DM), organic matter and particulate matter concentrations were measured and the particle size distribution of rumen contents was analysed using a wet sieving technique.3. There was a similar exponential loss of DM from the rumen with time after feeding for both perennial ryegrass and white clover. The rate of DM disappearance during the first 3 h after feeding was ten times greater for the higher intake and seven times greater for the lower intake than during the subsequent 21 h. The percentage of particulate material disappearingduring the first 3 h was greater for white clover (57% )than for perennial ryegrass (49%).4. Particle size distribution analysis of rumen contents showed that the most rapid rate of particle size reduction occurred during the first 3 h after feeding. Despite a rapid rate of breakdown there was no increase in the total weight of small particles in the rumen.5. The rate of reduction in particle size during this period was greater for white clover than perennial ryegrass.6. Microscopic examination of rumen particles showed a difference in particle geometry between white clover and perennial ryegrass which appeared to be related to anatomical features of the plant.