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Biomedical subjects

R J Neale

Publications and source records attributed to R J Neale.

At least 19 recordsLinked to original sources
PubMed1989

Effects of dietary iron deficiency and tungsten supplementation on 59Fe absorption and gastric retention from 59Fe compounds in rats.

1. In vivo 59Fe absorption from intrinsically labelled Fe-containing fractions of liver and blood were measured in rats by intragastric dosing. All rats were fed on a low-Fe diet for 3 d before dosing in order to standardize the Fe status of the intestinal mucosal cells. 2. An increase in digestion time from 2 to 12 h increased 59Fe absorption (P less than 0.01) from all fractions except ferritin. 3. Fe-deficient rats when compared with essentially Fe-replete rats showed decreased gastric retention for all fractions, but increased 59Fe absorption over 2 h only from ferritin. Ferritin showed several unusual absorption characteristics. 4. Dietary tungsten supplementation of Fe-deficient rats reduced the ferroxidase activity of intestinal mucosal xanthine oxidase. In addition, gastric retention and 59Fe absorption (P less than 0.05) from all fractions were increased.

Animals↗
PubMed1988

Dietary fibre and health: the role of hydrogen production.

The biological basis for the epidemiological association between high dietary fibre intakes and reduced disease incidence in Man is not fully understood. It is proposed that molecular hydrogen, produced in quite large amounts as a by-product of colonic fermentation of dietary fibre and unabsorbed carbohydrate may play an important role. Hydrogen in the tissues may act as a powerful reducing agent (antioxidant) of potentially damaging free radical species (e.g. singlet oxygen) and in so doing, along with other antioxidants would help in the control of these potentially damaging species and their known involvement in disease causation.

Adolescent↗
PubMed1988

The excretion of large vitamin C loads in young and elderly subjects: an ascorbic acid tolerance test.

An ascorbic acid tolerance test is described for assessing vitamin C status. The test is simple to administer and suitable for elderly patients. It involves giving an oral load of 1 g ascorbic acid in water and then measuring urinary excretion of vitamin C over the next 6 h. The excretion pattern at dosing has been studied in ten young subjects. The result of the ascorbic acid tolerance test in these young subjects was significantly different after supplementation with 1 g ascorbic acid daily for 1 month. Two series of elderly patients were also studied with the ascorbic acid tolerance test. They had low initial plasma ascorbic acid levels and much less vitamin C was excreted in the urine after dosing. Seven of these elderly patients were then supplemented with 1 g ascorbic acid for 1 month. After supplementation the initial plasma levels and their response to the ascorbic acid tolerance test became similar to that seen in younger subjects.

Administration, Oral↗
PubMed1986

Pigeon (Columba L.) meat iron solubility and availability for absorption in rats.

1. The distribution of iron in 59Fe-labelled pigeon (Columba L.) leg and breast muscle and liver were determined by gel filtration. While the insoluble Fe was between 14 and 25% of the total Fe from the tissues, the haem-Fe represented 79.1% (breast) to 45% (liver) of the total Fe and ferritin was between 5.5% (breast) and 26.5% (liver) of the total Fe. 2. The tissue haem-Fe concentration was found to be lower than that determined by gel filtration using the method of Schricker et al. (1982) for non-haem-Fe and obtaining haem-Fe by difference. 3. A simulated in vitro digestion procedure showed significantly (P less than 0.01) reduced 59Fe solubility from 59Fe-labelled pigeon meat after cooking at 90 degrees for 30 min. 4. 59Fe absorption from whole pigeon meat and soluble extract was significantly reduced by cooking when given to Fe-replete rats. Cooking liver, however, slightly improved 59Fe absorption in Fe-replete rats. 5. 59Fe absorption from the separated pigeon-meat fractions (haemoproteins, ferritin and haemosiderin) was variable but considerably lower than that from whole meat. 6. The relative distribution of Fe compounds in meat, the processing conditions they are subjected to and the protein content and composition may all influence the absorption of meat-Fe to some degree.

Absorption↗
PubMed1986

Effect of soya-bean protein on meat iron solubility and absorption in rats.

1. Soya-bean proteins were used to replace 30 and 50% of the protein from 59Fe-labelled pigeon (Columba L.) and chicken meat, and the solubility of the meat 59Fe in vitro and its absorption in vivo in rats in the presence and absence of soya-bean proteins were measured. 2. Replacement of part of the chicken meat by soya-bean proteins reduced 59Fe solubility from chicken meat at all stages during simulated in vitro digestion. 3. 59Fe absorption from 59Fe-labelled chicken meat when given to both Fe-replete and Fe-deficient rats was reduced in the presence of soya-bean proteins but was unaffected by the presence of casein or bovine serum albumin. 59Fe-absorption from pigeon meat in the presence of soya-bean proteins was not reduced to the same extent as that from chicken meat. 4. There was no significant effect of soya-bean proteins on 59Fe-labelled haemoglobin Fe absorption in vivo in Fe-replete rats. 5. Absorption of 59Fe from the isolated haemoproteins from chicken meat was unaffected by soya-bean proteins but 59Fe absorption from the main non-haem-Fe fractions was strongly inhibited, particularly from haemosiderin.

Absorption↗
PubMed1979

Nutritional effects of field bean (Vicia faba L.) proteinase inhibitors fed to rats.

1. Weanling rats were fed on purified-casein diets containing active and inactive (autoclaved) field bean (Vicia faba L.) proteinase inhibitors (PI) at levels of 1.25, 2.5, 5.0 and 10 g/kg. Diets containing raw- and autoclaved-field-bean meal (FBM) were also given. The body-weight gain, protein efficiency ratio (PER); i.e. the ratio of the live weight gain in g/g of protein consumed and apparent nitrogen digestibility were determined 7, 14 and 21 d after the start of the trial. 2. Significant growth depression (P less than 0.001) was observed in rats given diets containing 2.5 g/kg PI (27--35%). In rats fed on raw FBM growth depression was severe after 7 d (57%). 3. Food intake was depressed at PI inclusion levels of 5 g/kg and higher between 14 and 21 d. 4. PER was depressed significanlty (33-44%) in rats given diets containing the active PI at all levels after 7 d. The protein utilization of all casein diets was higher than that of the FBM diets. 5. Apparent N digestibility was depressed in rats fed on diets containing 10 g/kg PI by 9 and 7% at 14 and 21 d respectively. The N digestibility of both raw and heated FBM was similar at approximately 84%. 6. It was concluded that the PI are not the main factors responsible for the growth depression observed when raw FBM is fed to rats.

Animals↗
PubMed1978

Iron availability from meat.

1. The distribution of radioactive iron in 59Fe-labelled rat muscle extract was determined using gel filtration. This showed that most (approximately 70%) of the radioactivity was associated with the heamatin compounds; myoglobin and haemoglobin. 2. Raw beef and freeze-dried rat muscle were digested in vitro, under simulated physiological conditions, and after centrifugation the supernatants fractionated by gel filtration. The soluble products were haematin Fe complexes of molecular weight above 10,000 and non-haematin Fe compounds of molecular weight below 6000, the major products being the non-haematin Fe complexes. The soluble compounds were also separated by dialysis and, in rat muscle, it was found that the low-molecular-weight non-haematin compounds accounted for more than 80% of the total soluble iron. 3. In vivo absorption studies with rats showed the Fe in a digested muscle dialysate to be more readily absorbed than that from an aqueous muscle extract which itself was more readily absorbed than the Fe from whole blood. 4. It may not, therefore, be the haemoproteins per se which are responsible for the high availability of Fe in meat, but rather the nature of their degradation products, formed by digestion within the meat environment.

Animals↗
PubMed1978

Protein quality and iron availability of intermediate moisture beef stored at 38 degrees C.

The longissimus dorsi of a bull and steer were cut into cubes 1.5 cm3 and processed to a water activity (aw) 0.85 by canning in a solution of 9.5 p. 100 sodium chloride, 0.5 p. 100 potassium sorbate and a pre-determined amount of glycerol and water for sixteen hours with continuous tumbling on an end over shaker. After partial drying the intermediate moisture (i.m.) meat pieces were stored at 38 degrees C for periods up to 24 weeks and then freeze-dried before milling and incorporation into test diets fed to rats. Protein quality of fresh cooked beef and i.m. meat stored at 38 degrees C was measured in terms of net protein utilisation (NPU). There was no significant difference in NPU between cooked beef and freshly processed i.m. beef. There were no changes in NPU of i.m. meat from bull up to 9 weeks of storage. After 3 weeks of storage of the meat from the steer however, the NPU fell to 53.0, a level characteristic of cereal protein. This fall in NPU was associated with a decrease in the levels of all essential amino acids (in the protein hydrolysate). Valine and threonine being first and second limiting amino acids. Further storage of i.m. beef after 3 weeks produced a slower rate of decrease in NPU, the value at 24 weeks being 32.1 (61 p. 100 fall). Available lysine decreased by only 15 p. 100 after twenty-four weeks, this measurement under-estimating the fall in protein quality. The decrease in solubility of the meat in SDS/beta-mercaptoethanol on storage was of similar magnitude to that of NPU. Iron availability of i.m. meat, measured by haemoglobin regeneration in rats, showed improved iron availability compared to freshly cooked beef, even though marked changes had occurred in the meat heamatin complexes.

Animals↗
PubMed1977

Endogenous loss of leucine and methionine in adult male rats.

1. The fractional rate of loss of 14C and body-weight was measured in adult male rats after giving 14C-labelled methionine or leucine and maintaining rats for 30 d on a low-protein or a specific methionine+cystine-free diet: carcasses were then analysed for protein and fat 14C radioactivity. 2. The fractional loss of 14CO2 from [14C]methionine or [14C]leucine between day 20 and day 30 was always greater than the fractional loss of body-weight. 3. Carcass protein 14C radioactivity after giving [14C]leucine was higher than after giving [14C]methionine, but fat 14C radioactivity after either 14C-labelled amino acid was only a small proportion of the total body 14C radioactivity. 4. After correction of the fractional loss of 14CO2 for urinary 14C loss, but not body-weight loss, absolute amino acid loss was calculated using published values for methionine and leucine content of rats. 5. The best estimates of endogenous amino acid loss obtained using I-14C-labelled amino acids, expressed as mg/kg body-weight 0.75 per day were leucine 79, methionine 38.

Animals↗