Biomedical subjects
Publications and source records attributed to A Faulkner.
Propionate metabolism was studied in ovine hepatocytes. The main products of metabolism were CO2, glucose, L-lactate and pyruvate. The fatty acids, butyrate and palmitate inhibited propionate oxidation; butyrate inhibited but palmitate slightly stimulated gluconeogenesis from propionate. Butyrate and palmitate also inhibited lactate and pyruvate production from both endogenous substrates and from propionate.
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The effects of intramammary injection of vincristine on milk secretion were studied in goats. Vincristine inhibited milk secretion in a dose-dependent manner, with 1 mg decreasing milk yield to approximately 40% of previous yield. The inhibition was reversible with a full recovery of milk yield within a few days. During inhibition, there were significant changes in milk composition; Na concentration increased and K and lactose concentrations decreased, while Cl concentration was unaffected. Fat, protein, citrate and Ca concentrations all increased, particularly as milk yield was recovering. The concentrations in milk of the two lactose precursors, glucose and UDP-galactose, both increased. During inhibition and recovery, the secretion rates of three major components of milk, lactose, protein and fat, were affected to a different degree, with lactose secretion being inhibited to the greatest extent. The results are discussed in relation to the action of vincristine on milk secretion. It is proposed that vincristine's actions include a specific inhibition of lactose synthesis.
Two models for pitch discrimination of harmonic complex sounds are discussed, a multiple-band probability summation model using comparisons among component frequencies, and a model in which residue pitches are compared. The second model is based on Goldstein's optimum-processor pitch theory [J. Acoust. Soc. Am. 54, 1496-1516 (1973)], and is distinguished from the multiple-band model by an internal noise process. Pitch difference limens from 2I2AFC tasks show that when the test signals comprise corresponding harmonics, relative pitch difference limens are less than the smaller relative difference limens for the component frequencies, which is consistent with the multiple-band model. The absence of corresponding harmonics significantly reduces relative pitch discriminability; this effect supports the model on Goldstein's theory. It appears that residue pitch comparisons are not used for pitch discrimination between sounds with corresponding components; rather, comparisons based on residue pitch are only employed where there are no common resolved components in the signals to be discriminated.
The effects of colchicine and vincristine on the concentration of glucose and its metabolites in milk were studied following intramammary injection of the alkaloids into one mammary gland of lactating goats. Both alkaloids decreased the rate of milk secretion from the treated gland and produced similar changes in the concentrations of various metabolites in milk. The concentrations of glucose, UDP-galactose, galactose, pyruvate and lactate increased, while those of glucose 6-phosphate and phosphoenolpyruvate decreased in milk from treated glands. The rate of milk secretion from the untreated gland increased, along with the concentrations of glucose in the milk. The changes in the concentrations of the metabolites in milk are discussed in relation to possible biochemical changes occurring in the mammary gland during the suppression of milk secretion by the alkaloids. It is suggested that, before alkaloid treatment, the rate of milk secretion was limited by intracellular glucose supply.
Concentrations of cAMP and cGMP were measured in mammary secretions of goats. [cAMP] and [cGMP] increased during late pregnancy. At the onset of copious milk secretion, [cGMP] decreased while [cAMP] increased further. After the cessation of milking in late lactation, [cGMP] increased and [cAMP] tended to decrease. During withdrawal of food for 48 hr, the rate of milk secretion fell, [cGMP] increased and [cAMP] decreased; the changes were reversed on re-feeding. During temporary inhibition of milk secretion by intramammary treatment with colchicine, [cGMP] increased while [cAMP] decreased. It is concluded that cyclic nucleotide concentrations in milk change with physiological state.
Eight ward nurses were trained to assess psychological and physical adjustment following mastectomy. Training included provision of a standard assessment form, practice interviews and audiotape feedback of performance. All nurses improved in their ability to cover salient areas, the use of relevant interviewing techniques and identification of problems. They also reported greater job satisfaction and had used their new skills with other patients. These findings, albeit with a small sample, suggest that other general nurses could, with similar training, play an important part in the early recognition of the psychological problems which can develop in cancer patients.
1. The following were measured in pieces of perirenal adipose tissue obtained from foetal lambs at about 120 days of gestation or within 3 days of term, and 9-month-old sheep: the rates of synthesis from glucose of fatty acids, acylglycerol glycerol, pyruvate and lactate; the rate of glucose oxidation to CO2 and the proportions contributed by the pentose phosphate cycle, pyruvate dehydrogenase and the tricarboxylic acid cycle; the activities of hexokinase, glucose 6-phosphate dehydrogenase, phosphofructokinase, pyruvate kinase and pyruvate dehydrogenase. 2. The total rate of glucose utilization was lower in pieces of adipose tissue from near-term lambs than 120-day foetal lambs and the pattern of glucose metabolism differed, with, for example, a much smaller proportion of glucose carbon being used for fatty acid synthesis, whereas a greater proportion of glucose oxidation occurred via the tricarboxylic acid cycle in the near-term lambs. In general, these differences in glucose metabolism were not associated with differences in the activities of the various enzymes listed above. 3. The rates of glucose utilization per fat-cell by 120-day foetal lambs and 9-month-old sheep were very similar but, again, the proportions metabolized to the various products differed. In particular, there was a smaller proportion of glucose oxidized via the pentose phosphate cycle and a greater proportion oxidized via pyruvate dehydrogenase and the tricarboxylic acid cycle in adipose tissue from foetal lambs. These differences were matched by a lower activity of glucose 6-phosphate dehydrogenase and a higher pyruvate dehydrogenase activity in fat-cells from the foetal lambs.
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1. Glucose turnover in fed and 48 h-starved lactating goats was determined during a glucose load of 500 mumol/min using a continuous infusion of [U-14C]- and [3-3H]glucose. 2. Endogenous rates of irreversible glucose turnover (i.e. total rates of irreversible glucose turnover minus the rate of exogenous glucose supply) were depressed during glucose loading by 14 and 62% in the fed and starved animals respectively. 3. Plasma glucose concentrations increased significantly by 57 and 88% in the fed and starved goats respectively. Plasma insulin concentrations increased by 108 and 128% in the fed and starved animals respectively. 4. Milk yields increased significantly (41%) in the starved animals during glucose loading, but were unaffected in fed animals. 5. In both the fed and 48 h-starved goats, mammary glucose metabolism via glycolysis and the pentose phosphate pathway appeared to be stimulated by glucose loading.
1. The following were measured in adipose-tissue pieces, obtained from 7-9 month-old sheep, before or after the tissue pieces had been maintained in tissue culture for 24 h: the rates of synthesis from glucose of fatty acids, acylglycerol glycerol, pyruvate and lactate; the rate of glucose oxidation to CO(2); the rate of glucose oxidation via the pentose phosphate pathway; the activities of hexokinase, glucose 6-phosphate dehydrogenase, phosphofructokinase, pyruvate kinase, pyruvate dehydrogenase and ATP citrate lyase; the intra- and extra-cellular water content; the concentration of various metabolites and ATP, ADP and AMP. 2. The proportion of glucose carbon converted into the various products in sheep adipose tissue differs markedly from that observed in rat adipose tissue. 3. There was a general increase in the rate of glucose utilization by the adipose-tissue pieces after maintenance in tissue culture; largest changes were seen in the rates of glycolysis and fatty acid synthesis from glucose. These increases are paralleled by an increase in pyruvate kinase activity. There was no change in the activities of the other enzymes as measured, although the net flux through all the enzymes increased. 4. Incubation of fresh adipose-tissue pieces for 2-6h led to an increase in the affinity of pyruvate kinase for phosphoenolpyruvate. 5. The rate of pyruvate production by glycolysis was greater than the activity of pyruvate dehydrogenase of the tissue. 6. The results suggest that both pyruvate kinase and pyruvate dehydrogenase have important roles in restricting the utilization of glucose carbon for fatty acid synthesis in sheep adipose tissue.
1. The rates of fatty acid and acylglycerol glycerol synthesis from acetate, glucose and L-lactate in isolated liver cells from foetal lambs at about 30 and 3 days before birth are reported. The total rates of fatty acid synthesis from endogenous precursors and added substrates, measured using 3H2O, are also reported for these liver cells. 2. The total rate of fatty acid synthesis did not differ at the two ages. Of the added substrates, acetate and L-lactate were better precursors for fatty acid synthesis than glucose under the conditions used. Endogenous precursors, probably glycogen glucose, made a substantial contribution to fatty acid synthesis. 3. Results are compared with previous studies of fatty acid synthesis in adipose tissue from foetal lambs.
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1. Glucose turnover (i.e. glucose entry and utilization rates) in fed and 48 h starved goats during pregnancy and lactation was determined using a continuous infusion of [U-14C)- and [3-3H]glucose. 2. Glucose synthesis and utilization increased during pregnancy and lactation in fed but not in starved goats. 3. Recycling of glucose-C was approximately 10% in fed animals and 15-20% in starved animals and was unaffected by the stage of pregnancy or lactation. 4. Plasma glucose concentrations were maintained during pregnancy and lactation in fed goats but decreased during 48 h starvation in pregnant goats. Little change was seen in the plasma concentration of lipids and their metabolites during pregnancy and lactation in fed goats, but increases were observed after 48 h starvation. 5. The control of glucose metabolism in ruminants during pregnancy and lactation is discussed.