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Biomedical subjects

G H Anderson

Publications and source records attributed to G H Anderson.

At least 145 records · Page 8Linked to original sources
PubMed1983

Nutrient control of brain neurotransmitter synthesis and function.

Dietary fluctuations in nutrient availability are factors in the regulation of brain function. Until recently the prevailing view was that brain biochemistry and function were influenced by diet only when biochemical and clinical evidence of nutrient deficiency was present. It is now clear, however, that the brain is sensitive and responsive to diet composition. Preliminary data show that variation in vitamin and mineral nutrient intakes over ranges that are considered to maintain normal nutritional status may impact on brain biochemistry, owing to their many coenzyme roles. Furthermore, the synthesis of at least five brain neurotransmitters, namely serotonin, the catecholamines, acetylcholine, histamine, and glycine responds to dietary fluctuations in availability of their nutrient precursors, tryptophan, tyrosine, choline, histidine, and threonine, respectively. Not only are these biochemical events altered by normal variations in diet composition, but considerable evidence now exists to show that the brain uses this information to regulate many functions. Future studies can be expected to continue to elucidate the links between diet, brain neurotransmission, and brain function, and to exploit the application of these links in understanding the function of the brain under normal and disease conditions.

Animals↗
PubMed1983

Trace mineral balances in preterm infants fed their own mother's milk.

Balance studies were conducted on preterm infants (birthweight, 1,500 g or less) fed their own mother's milk or formula (SMA with iron) to compare the relative adequacy of these sources for copper (Cu), iron (Fe), and zinc (Zn). Urine and stools were collected for 72 h from infants aged 1, 2, or 4 weeks while they were fed milk or formula. Infants fed SMA 24 (but not SMA 20) received Cu, Fe, and Zn intakes within the recommended range. They did not, however, achieve estimated in utero retention rates for Fe, and were in negative Cu balance; they did approach in utero retention rates for Zn. Infants fed their own mother's milk received Cu and Zn, but not Fe, in recommended amounts. They achieved in utero retention rates for Cu at each age studied and approached the estimated in utero retention rates for Zn at 4 weeks, but they retained insufficient Fe throughout. Thus, neither the infant's own mother's milk nor this particular formula provides ideal amounts of all three minerals studied--Cu, Zn, and Fe--during the 1st month of life.

Copper↗
PubMed1982

Meal composition influences subsequent food selection in the young rat.

Food selection one-half hour after the ingestion (2 g) of either a protein containing or a protein-free (carbohydrate) diet was studied in young rats. Following a 12 hr fast the rats were allowed 15 minutes to consume the meal (premeal). Thirty minutes later, they had access to two isocaloric diets that differed only in protein and carbohydrate content. During the first hour of ad lib feeding, protein intake and protein concentration selected were lower in the 45% casein prefed group compared to the carbohydrate group. A further reduction in protein intake and protein concentration occurred when the protein content of the premeal was increased to 70% from 45% casein. Rats prefed with the 70% casein diet significantly reduced their daily total food intake (12 hr) compared to either the 45% casein or carbohydrate prefed group. It is concluded that both quantity and composition of food selected is influenced by the composition of the preceding meal.

Aging↗
PubMed1982

Zinc, copper and iron content of milk from mothers of preterm and full-term infants.

Complete 24-hour expressions of milk were collected over the first month of lactation from mothers giving birth at term (FT) and prematurely (PT). Samples were analyzed for Cu, Fe and Zn concentration. Composition of PT and FT milks was similar during the first 4 weeks of lactation, but the concentrations of each mineral were higher during the first week than during the fourth week. From these data, the intakes of premature infants fed their own mother's milk were estimated and the proportion which must be absorbed and retained in order to accumulate the amounts laid down in utero were predicted. On the basis of these estimates, preterm infants who retain 25% of the Zn and 35% of the Cu in PT milk would approximate in utero accumulations. However, the Fe content of PT milk is unlikely to provide for in utero accretion rates, even if 100% absorption as achieved.

Adult↗
PubMed1982

Sulfur balances in intravenously fed infants: effects of cysteine supplementation.

Sulfur balances were completed in newborn infants parenterally fed with or without cysteine. In both groups, the preservative, potassium metabisulfite, accounted for the majority of sulfur intake (32 mg S/kg/day), while methionine intakes provided an additional 27 sulfate losses accounted for approximately 95% of the sulfur excretion, with the remainder contained in amino acids. Balance data accounted for over 99% of the sulfur infused in the unsupplemented group, but only 90% of that given to the cysteine-supplemented group. Thus, urinary excretion of sulfate generally reflects input from either inorganic or amino acid sources. Of the sulfur retained in the supplemented group, 75% was calculated to be retained in lean tissue and in increases in total body sulfate, but the distribution of the remaining 25% remains unknown. The failure to account fully for the sulfate provided to the cysteine-supplemented group, however, may be due to errors in the balance technique or due to an accumulation of cysteine or sulfate in body pools undefined by this study.

Amino Acids↗
PubMed1982

Relationships among maternal diet, serotonin metabolism at weaning, and protein selection of progeny.

Brain serotonin (5HT) metabolism in rats at weaning was examined in relation to their maternal dietary protein (PC) and tryptophan (TRP) concentration and to their protein feeding behavior. Pup brain TRP, 5HT, and 5-hydroxyindoleaceticacid (5HIAA) concentration was unaffected by maternal diet PC (10, 20, or 40%) but was increased by TRP additions (0.66 or 1.86%) to 40% casein diets. Turnover of brain 5HT, measured at weaning after probenecid injection, was inversely related to maternal diet PC (r = .54, P less than 0.05) but was not affected by TRP supplementation. Pups allowed to select from 10 and 60% casein diets selected during the first 3 days post-weaning, dietary PC which reflected the PC (r = 0.65, P less than 0.01), but not RRP content of their maternal diet, and also reflected brain 5HT turnover (r = .50, P less than 0.05), but not concentration, of their littermates. Thus, the relationship dietary PC to protein selection by the offspring is associated with maternal diet-maternal diet-induced changes in their brain 5HT turnover, at least as measured after probenecid administration.

Animals↗
PubMed1982

Self-selected meal composition, circadian rhythms and meal responses in plasma and brain tryptophan and 5-hydroxytryptamine in rats.

Relationship among food composition, plasma and brain tryptophan and 5-hydroxytryptamine (5-HT) were studied by measuring both carcadian feeding and meal responses in self-selecting rats. Under ad libitum feeding conditions in which young rats were given a choice between two isocaloric diets (0 and 60% casein) and groups were killed at 3-hour intervals throughout the day, several circadian rhythms become apparent. Protein and carbohydrate energy, the plasma tryptophan:neutral amino acid ratio (TRP:NAA) and brain TRP, but not 5-HT concentrations showed statistically significant circadian variations. During the dark hours of plasma TRP:NAA ratio and brain TRP concentrations were inversely associated with the protein concentration of meals previously selected. In meal response studies, rats were similarly given a choice of diets, but were killed 20 minutes after their selected meals. Plasma TRP:NAA ratios, brain TRP and 5-hydroxyindole levels were inversely correlated with the protein concentration of the meals selected. Absolute quantities of protein, but not carbohydrate, fat or total energy, were inversely related to the plasma TRP:NAA ratio and brain TRP concentration. It is concluded that the circadian changes in the plasma TRP:NAA ratio and in brain TRP amd 5-hydroxyindole concentrations are under the continual influences of food choices made during spontaneous feeding activity.

Amino Acids↗
PubMed1982

Dietary minerals modify the food intake suppressing effects of high casein diets fed to rats.

Food intake, growth, and urinary urea and ammonia excretion were studied in young rats undergoing adaptation to high protein diets (70% casein) containing varying amounts of potassium, sodium and chloride. Two commercial mineral mixtures were used. The Bernhart-Tomarelli (BT) mineral mixture is low in K, Na and Cl compared to the TD (modified Williams-Briggs) mineral mixture. Rats consumed significantly less food and had poor growth when fed 70% casein diets containing the BT mineral mixture. Food intake and feed efficiency improved significantly when the BT diets were supplemented with KCl and NaCl, Na acetate or K acetate but not 3-chloropropionate. Urinary urea and ammonia excretion were directly proportional to food (protein) intake. However, body weight gain during the last 3 days of the 9-day study (experiment 3) was negatively correlated with urinary ammonia nitrogen (milligrams per gram food eaten) but not with urinary urea nitrogen. It is concluded that dietary K and/or Na content affects food consumption in rats fed high casein diets. Alterations in renal capacity for handling ammonia may be responsible for the food intake enhancing effect of K or Na in rats fed a high casein diet.

Ammonia↗
PubMed1982

Prediction of plasma amino acid concentration from diet amino acid content.

The level of each plasma amino acid in male weanling rats was examined in relation to their intake from gluten, casein, synthetic amino acid, or zein diets. Plasma levels of valine, leucine, and isoleucine were found to be linearly related to the intake per gram diet regardless of the dietary source. Although levels of most other amino acids were not linearly related to intake, they were predictable if both the concentration of the amino acid in the diet and chronic level of protein intake were known. That is, a relationship, which applied to all diets, was found between the concentration of amino acid in the plasma, the concentration in the diet, and the total protein or amino acid nitrogen in the diet.

Amino Acids↗
PubMed1982

Preoperative and postoperative renin levels in coarctation of the aorta.

We studied plasma renin activity (PRA) in eight children before and after surgical correction of aortic coarctation. These eight children underwent a combination of low-sodium diet and diuresis before surgery, and PRA was measured shortly thereafter. Thirty-two to 51 months after successful surgical correction, PRA was measured again. The mean PRA was 21.4 +/- 1.3 ng/ml/hour (+/- SD) preoperatively and 5.5 +/- 1.5 ng/ml/hour postoperatively. These findings provide further evidence of the significance of increased renin-angiotensin activity in patients with aortic coarctation.

Adolescent↗
PubMed1982

The development of cystathionase activity during the first year of life.

The development of hepatic cystathionase (EC 4.4.1.1) activity is dependent both upon the gestational age of the infant and the postnatal age. Full-term infants are born with greater hepatic cystathionase activity than pre-term infants, and the activity increases rapidly after birth reaching mature levels at about 3 months of age. Prematurely born infants have lower hepatic cystathionase activity at birth and like the full-term, the activity increases after birth. Cystathionase activity is not isolated to the liver. In both premature and full-term infants, it is present in the kidneys, and adrenals, but of little significance in the pancreas. These in vitro measurements of cystathionase activity indicate that the premature infant is potentially capable of endogenous cysteine production if provided with adequate methionine.

Age Factors↗
PubMed1982

Simplified screening procedures for primary aldosteronism. Studies on the mechanism of the hyper-responsiveness to furosemide and standing.

Screening tests for primary aldosteronism were compared in 22 patients with this disorder and 140 hypertensive controls. Adequate (93-100%) sensitivity and specificity were not provided by single tests ((1) serum K, (2) furosemide-stimulated PRA, or (3) plasma aldosterone concentration (PAC) after furosemide, or (4) after 2 liters 0.9% NaCl)), but were provided by combinations: (2) + (1) or (3); (2) + (1) or (4); and by a pressor response to saralasin + (3) or (4). Mechanism of the observed excessive rise in PAC "stimulated" by furosemide and standing for 2 h was studied in the same patients. The rise in "stimulated" PAC was (a) associated with a low PRA and not reproducible by angiotensin II infusions; (b) associated with a slight but significant rise in plasma cortisol and was reproducible by ACTH infusions. It is, therefore, attributed to the effects of slight ACTH release acting on adrenal tissue with super-sensitivity of aldosterone response to ACTH.

Aldosterone↗
PubMed1982

Colposcopy, conization, and hysterectomy practices: a current perspective.

Data from the provincial cytology program has shown a progressive increase in the number of cases of cervical carcinoma in situ detected in the general population and a doubling of disease rate in third decade women, with most of the cases now in the 25- to 29-year-old age group. The introduction of a colposcopy service has led to a significant decrease in the number of diagnostic conizations performed over a 5-year period. Conization was still used for therapy in a substantial number of women despite the availability of cryotherapy and laser surgery. Eighty-five percent of all patients undergoing cone biopsy had sever dysplasia or carcinoma in situ (CIN III) on pathological examination. In 25% of patients, the conization specimen revealed either dysplasia or carcinoma in situ extending to resection margins. During review of 2249 patients, 1174 were spared a conization and were treated by either hysterectomy, cryotherapy, or laser surgery. It would appear that, although colposcopy can reduce dramatically the number of diagnostic cone biopsies, conization will still be required for therapy in a substantial number of patients.

Adult↗
PubMed1981

Iron intake of infants: the importance of infant cereals.

Since 1976 many baby foods have been reformulated and the iron used to fortify infant cereals has been changed to a more bioavailable form. Therefore, the dietary intake of iron by infants from 1 to 18 months of age was assessed in a longitudinal survey conducted in Toronto and Montreal between 1977 and 1979. Except in the 1st and 18th months the mean daily iron consumption of the infants was above that recommended in the Dietary Standard for Canada. The main source of this nutrient was infant cereals. Examination of the diets of the infants who did not have the recommended daily intake of iron showed that they did not consume sufficient amounts of infant cereals and other iron-rich foods. These results indicate that without such cereals it is difficult to provide infants with the amount of iron they need. Therefore, infants should receive these cereals during the first 2 years of life.

Biological Availability↗