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Biomedical subjects

R H Smith

Publications and source records attributed to R H Smith.

At least 181 records · Page 10Linked to original sources
PubMed1976

Turnover of plasma glucose and free fatty acids in patients on the first day after myocardial infarction.

1. The turnover of plasma glucose and free fatty acids was measured in ten patients within 24 h of the onset of symptoms of acute myocardial infarction and in two with symptoms of acute myocardial ischaemia. The measurements were repeated in seven of the patients 12-40 weeks after the acute episode. 2. Both for the patients with acute myocardial infarction alone and for all the individuals studied the turnover of glucose increased with plasma glucose concentration but was not related to the turnover of free fatty acids or the plasma concentrations of free fatty acids, insulin or total catecholamines. There was no obvious difference in the nature of the glucose turnover-concentration relationship between the patients with acute myocardial infarction, with acute myocardial ischaemia and on re-examination. 3. For all the individuals studied the turnover of free fatty acids increased with the concentration of these but was not related to the turnover of glucose or the plasma concentrations of glucose, insulin or total catecholamines. There was no obvious difference in the nature of the free fatty acids turnover-concentration relaionship between the patients with acute myocardial infarction, with acute myocardial ischaemia and on re-examination.

Adult↗
PubMed1976

Nitrogen metabolism in calves. Effect of giving different amounts of dietary casein with and without formaldehyde treatment.

I. Calves were given a basal diet of straw and flaked maize (12 g nitrogen/kg dry matter (DM)) or diets with some flaked maize replaced by untreated (UT) casein or formaldehyde-treated (FT) casein to give 19, 29 or 34 g N/kg DM. 2. At all intakes rumen ammonia concentrations were lower and amounts of total-N, non-ammonia-N and amino acid-N entering the duodenum were high when FT-rather the UT-casein supplements were given. 3. Direct measurement of casein entering the duodenum indicated that giving FT rather than UT casein led to much greater amounts of dietary casein escaping degradation in the rumen (70--90% compared to 10--20%). Calculated values for fermentable N indicated that with this low degradability diets containing FT-casein would have provided inadequate N for maximum microbial synthesis in the rumen, and this probably accounted for the marked reduction in amounts of non-casein-N entering the duodenum when FT rather than UT casein was given. 4. Amino acid patterns in duodenal digesta samples after giving the basal diet or diets containing UT-casein were similar. Giving diets containing FT-casein led to changes in this pattern which could sometimes, although not always, be accounted for by estimated differences in proportions of dietary and microbial proteins. 5. At the highest level of N intake FT-casein-supplemented diets led to significantly higher concentrations of most essential amino acids and lower concentrations of most non-essential amino acids in plasma than did UT-casein-supplemented diets. Plasma urea concentrations increased with increasing N intake but were not significantly different for UT- and FT-casein-supplemented diets.

Amino Acids↗
PubMed1976

The effect of different diets including those containing soya-bean products, on digesta movement and water and nitrogen absorption in the small intestine of the pre-ruminant calf.

1. Preruminant calves, fistulated in the abomassum and distal ileum, were given by infusion into the abomasum, at intervals of 2-3 d, single experimental feeds of cow's milk or a synthetic milk diet in which the protein source was casein or a soya-bean product. Polyethylene glycol (PEG) and phenol red were included as markers. 2. After infusion of the experimental feed, measurements were made of transit time from proximal duodenum to distal ileum and mean ileal flow-rates for the first 3 and 21 h after food residues reached the distal ileum. PEG recoveries for these two periods and net nitrogen absorption up to the distal ileum were also determined. In some experiments sodium, potassium and magnesium concentrations and numbers of viable bacteria in ileal digesta were determined. 3. Measurements of passage of digesta, recovery of marker and net N absorption did not differ greatly between calves given cow's milk and the synthetic milk diet containing casein. Compared to the casein-based diet, a diet based on heated soya-bean flour given to a calf for the first or second time produced a somewhat higher ileal flow-rate and a significantly lower net N absorption. Net N absorption was even lower when a calf received a diet containing unheated soya-bean flour. 4. Calves given the diet containing heated soya-bean flour on several occasions appeared to develop a sensitivity to the flour, and after further feeds containing it they had significantly higher rates of ileal flow (accompanied by correspondingly high rates of Na and K flow), lower small intestine transit times and lower net N absorption values than similarly fed unsensitized calves. They also had significantly lower rates of passage of marker in the first few hours after food residues reached the ileum, indicating inhibition of abomasal emptying. Over all, the changes indicated a severe disturbance in digestive function which was not caused by abnormal bacterial growth and may have been due to a gastrointestinal allergy. 5. Diets prepared from water-extracted flour and from soya-bean-protein isolate also led to digestive disturbances in sensitized calves, but those containing concentrates prepared by extracting soya-bean meal with hot aqueous ethanol did not.

Abomasum↗
PubMed1976

Effect of dietary nitrogen source on carbohydrate metabolism in the rumen of the young steer.

1. Steers, fitted with simple rumen and duodenal cannulas, were given diets of approximately equal parts of flaked maize and hay (A) (containing 16 g nitrogen/kg dry matter (DM) or diets of flaked maize and straw supplemented with decorticated groundnut meal (B), fish meal (C), or heated (D) or unheated (E) soya-bean meal (containing 24 g N/kg DM). Chromic oxide was given as a marker with the feeds, and flows of different combined sugars at the duodenum estimated from the values for sugars:marker at this site. Contributions of bacterial constituents to these flows were estimated from amounts of RNA present. 2. Rumen bacteria from steers receiving diet A contained approximately 110 g alpha-dextran-glucose/kg DM and contributed about 60 g alpha-dextran-glucose/d at the duodenum; bacteria from steers receiving diets B, C, D or E contained 25-40 g alpha-dextran-glucose/kg DM and contributed about 20-30 g alpha-dextran-glucose/d at the duodenum. There were no significant differences between different N supplements. About half the alpha-dextran-glucose, varying amounts of the mannose and galactose, and nearly all the rhamnose and ribose in duodenal digesta were contributed by the bacteria. Almost all the arabinose, xylose and cellulose-glucose was of dietary origin. 3. For steers receiving diet A, mean coefficients of digestibility between mouth and duodenum, corrected where necessary for bacterial contribution, were 0-96, 0-73, 0-58, 0-22 and 0-53 for starch-glucose, galactose, arabinose, xylose and cellulose-glucose respectively. Corresponding mean values when diets B, C, D and E were given, which did not differ significantly amongst themselves, were 0-98, 0-79, 0-81, 0-59 and 0-58. Most values for galactose, arabinose and xylose were significantly higher than the diet A values.

Animal Feed↗
PubMed1976

Infective endocarditis: a survey of cases in the South-East region of Scotland, 1969-72.

The incidence and characteristics of infective endocarditis were studied in a defined community over a four-year period. Seventy-eight cases were found, giving an incidence of 16 cases permillion per year. The commonest presenting features were those of infection; 53% had cardiac failure and 37% evidence of emboli when first seen. Twenty-three cases occurred on rheumatic heart valves, 13 on valvular prostheses, and 19 in previously normal hearts. Streptococcus viridans was the commonest organism, but there was a relatively high incidence of staphylococcal infection. Only four cases were preceded by dental manipulation, and no source for the infection was found in 46 patients. The mortality rate was 46%, cardiac failure and embolic phenomena accounting for 65% of deaths. It is unlikely that earlier diagnosis or cardiac surgery would have reduced the mortality appreciably.

Adolescent↗
PubMed1975

Concentrations of amino acids and urea in the plasma of the preruminant calf and estimation of the amino acid requirements.

1. A study was made of factors affecting the plasma concentrations of free amino acids (PAA) and urea (PU) in calves receiving liquid diets. 2. When calves were given whole milk (approximately 0-05 kg/kg live weight) at 10.00 and 17.00 hours there were marked decreases in PAA and slight decreases in PU for about 3-4 h after the morning feed. Both PAA and PU thereafter increased slightly and then remained constant for the next 10 h. In subsequent comparative experiments samples were taken 3 h after the morning feed. The variation in plasma methionine, isoleucine, leucine, phenylalanine, tyrosine and total PAA was apparently greater between than within animals. 3. In calves transferred from a diet of whole milk to one consisting of diluted whole milk supplemented with appropriate nutrients, including amino acids, but deficient in methionine, PU increased markedly and plasma methionine decreased. 4. Two calves (50-60 kg live weight) given the latter diet supplemented to give an intake of more than 4-5 g L-methionine/d together with 0-3 g cystine/d showed marked increases in plasma methionine. This was considered to correspond with the point at which methionine requirements were met and that under these conditions the methionine requirement for these calves (mean value plus or minus SE) was 4-5 plus or minus 0-2 g/d. In the same two calves PU decreased markedly with increasing levels of methionine supplementation up to 3-9 g/d and the estimated methionine requirement (mean value plus or minus SE) was 3-9 plus or minus 0-4 g/d.

Age Factors↗
PubMed1975

The effect of different feeds, including those containing soya-bean products, on the passage of digesta from the abomasum of the preruminant calf.

1. The effects of various factors on rates of flow and composition of digesta leaving the abomasum of preruminant calves were studied. The possible relation of some of these effects to the development of serum antibodies to certain dietary constituents has also been examined. Two situations were distinguished: (a) unsensitized responses, shown by calves receiving milk protein or soya-bean products for the first one or two occasions; (b) sensitized responses, shown by calves receiving certain soya-bean products, after a number of these feeds had been given. 2. For unsensitized calves, the rate of flow of total digesta from the abomasum was greater in the first few hours after a feed consisting of a mineral solution was given, than after cow's milk was given. This difference wasapparently due to differences in the composition of digesta entering the duodenum. Total digesta flows after giving synthetic milk feeds, prepared from different protein sources, were similar to those after cow's milk was given. 3. For sensitized calves, rates of flow of total digesta from the abomasum were greatly affected by the nature of the protein source used in the diet. Soya-bean flour (heated or unheated) generally caused inhibition of flow for some hours after feeding; a soya-bean protein isolate (isoelectric) had a similar but smaller effect, but a soya-bean concentrate (prepared by alcohol extraction of a soya-bean flour) and milk protein had little or no effect. The inhibition, believed to be a sign of more general disorders, appeared to be caused by a factor entering the duodenum which induced a change in the way in which the calf responded, probably as the result of a gastrointestinal allergy. 4. Calves given soya-bean flour or a soya-bean protein isolate (isoelectric) in their diets for several weeks, showed respectively high and low titres of serum antibodies to an antigen prepared from soya-bean flour. Calves given alcohol-extracted soya-bean concentrate had no similar antibodies. 5. In addition to variations in total digesta flow, dietary nitrogen compounds were held up in the abomasum to different extents after different feeds. After a whole-milk feed or a synthetic feed prepared from casein, a slow, steady release of N occurred over at least 9 h. N hold-up after giving soya-bean-containing feeds was slight for the soya-bean flour, but extremely marked for the soya-bean protein isolate (isoelectric). The latter hold-up was followed after several hours by a rapid outflow of N from the abomasum.

Abomasum↗