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Biomedical subjects

A Angel

Publications and source records attributed to A Angel.

At least 127 records · Page 7Linked to original sources
PubMed1977

The effect of gestational age on intralipid tolerance in newborn infants.

Tolerance to intravenously administered Intralipid was studied in 18 newborn infants aged 4 to 8 days and gestation 27 to 40 weeks. Clearance of a bolus injection of Intralipid from plasma was an exponential function following first order kinetics. Less mature infants had a clearance rate less than half that seen in more mature infants. Free fatty acids rose more rapidly and were maintained above fasting levels throughout the study in the immature group, probably because of impaired utilization of free fatty acid. The slower clearance of Intralipid in immature infants may be related to lipoprotein lipase deficiency secondary to their limited adipose tissue mass.

Clinical Trials as Topic↗
PubMed1977

A pharmacological study of the spontaneous convulsive activity induced by 1,2-dihydroxybenzene (catechol) in the anaesthetized mouse.

1. The convulsive activity induced by catechol has been examined in anaesthetized mice either by determining the CD50 for the convulsions in drug-treated and control animals, or by studying the effects of various drugs on the total whole body activity. 2. The results indicate that catecholamines play no part in the mechanism of action of catechol. Drugs which alter cerebral catecholamine levels had no effect on the convulsions, nor did the alpha- and beta-adrenoceptor blocking drugs. 3. 5-Hydroxytryptamine (5-HT) could possibly be important, though results with drugs which either change brain 5-HT levels, or block 5-HT receptors were inconsistent. 4. gamma-Aminobutyric acid also appears not to be involved in the mechanism of action of catechol. 5. The results strongly suggest that catechol primarily activates a central cholinergic system, in that muscarinic and nicotinic receptor blocking drugs inhibit, and anticholinesterases potentiate the convulsions.

Acetylcholine↗
PubMed1977

Insulin-like effects of fluoroacetate on lipolysis and lipogenesis in adipose tissue.

Hormone-stimulated lipolysis in adipose tissue was inhibited by fluoroacetate and there was a concomitant decrease in both the basal and hormone-stimulated cyclic AMP levels. Adenylate cyclase (EC 4.6.1.1) activity in membrane preparations was inhibited by fluoroacetate. There was no influence of fluoroacetate on the low Km cyclic AMP phosphodiesterase (EC 3.1.4.17) activity. The rate of glucose conversion to fatty acids was increased when adipose tissue was incubated in the presence of fluoroacetate. The outputs of pyruvate and lactate into the incubation medium were decreased at this time, suggesting decreased tissue pyruvate levels and a site of activation of lipogenesis distal to pyruvate formation. Pyruvate dehydrogenase (EC 1.2.4.1) activity was increased twofold in adipose tissue incubated in the presence of fluoroacetate. This was attributed to a fluoroacetate-induced inhibition of pyruvate dehydrogenase kinase, the enzyme responsible for inactivating the pyruvate dehydrogenase complex. Glucose transport was increased to a small but significant degree by fluoroacetate. In addition, both the tissue content of citrate and its release into the incubation medium were increased, suggesting that fluoroacetate resulted in an inhibition of aconitase (EC 4.2.1.3). The tissue ATP content was unchanged. Because the antilipolytic and lipogenic effects of fluoroacetate parallel those of insulin, they may share a common mechanism.

Adipose Tissue↗
PubMed1976

The effect of Intralipid on the estimation of serum bilirubin in the newborn infant.

After noting rises in measured serum billirubin in premature infants undergoing parenteral nutrition, a series of experiments was designed to ascertain the effect of the presence of Intralipid on the actual laboratory analysis. It has been shown that the most commonly used spectrophotometric analysis of bilirubin and the estimation of direct bilirubin by micromethods are affected by the presence of Intralipid in the specimens. Centrifugation of the blood samples at 15,000 rpm for 10 minutes and analysis of the aqueous layer overcomes, in both methods, the interference and error introduced by the presence of Intralipid chylomicrons in patient sera. Alternatively spurious bilirubin measurements due to hyperlipidemia may be avoided by using a bilirubinometer equipped with a filter which eliminates the effect of Intralipid interference.

Bilirubin↗
PubMed1975

Sensorimotor cortical representation in the rat and the role of the cortex in the production of sensory myoclonic jerks.

1. After administration of 1,2-dihydroxybenzene (catechol) to anaesthetized rats, rabbits and cats, a reflex jerk consisting of three distinct components was evoked in the limb muscles by peripheral stimulation. The second component of the jerk in the forelimb muscles of all three animals was specifically abolished by lesions confined to the contralateral forelimb sensorimotor cortex. 2. These lesions had no effect on the second response in either the hind limbs or in the forelimb ipsilateral to the lesion. The first and third responses were also unaffected. 3. Lesions in the cat hind-limb cortex abolished the contralateral hind-limb second response, but not the ipsilateral hind-limb or forelimb response. 4. In the rat and rabbit, unilateral hind-limb sensorimotor lesions were ineffective in completely abolishing the second response in the contralateral hind-leg muscles, and in addition, reduced the probability of occurrence of the response in the ipsilateral hind leg. Bilateral lesions abolished the response. 5. Re-investigation of the sensory and motor representation of the hind limb in the rat cortex revealed that this is bilateral in nature. Short-latency cortical responses (ca. 7-0 msec) could be evoked in one cortex by stimulation of either hind paw. The geometric centre of the cortical area from which these responses could be recorded was identical for each hind paw. 6. After catechol injection, stimulation of the cortical surface with single anodal shocks of threshold strength produced responses at similar latency (ca. 8-0 msec) in both hind limbs. 7. The behaviour of the second response after cortical lesions corresponds closely with the pattern of the somatosensorimotor cortical representation. The latency of the response is such as to allow its production by a long-loop cortical reflex, and this possibility is discussed.

Animals↗
PubMed1975

An analysis of the representation of the forelimb in the ventrobasal thalamic complex of the albino rat.

1. Glass micro-electrodes have been used to record from a total of 998 units situated in the ventrobasal thalamic complex in the deeply anaesthetized albino rat. 2. Of these units 889 responded to electrical stimulation of the contralateral forelimb and fifty-one to the contralateral hind limb. The remaining units consisted of those with receptive fields on the trunk, head and those which responded to stimulation of more than one limb. Only the latter group of units showed any spontaneous activity in the absence of intentional stimulation. 2. Of the units which responded to electrical stimulation of the contralateral forelimb the receptive fields, modality and latencies of response were accurately determined for 505 units. The mean latency to supramaximal stimulation at the wrist was 4.49 (+/- 0.04 S.E. of mean) msec; and to mechanical stimulation (for 146 of these units) at the centre of the receptive field 6.58 (+/- 0.12) msec. The modalities were distributed as follows: light pressure, 391; heavy pressure, 47; hair movement, 40; claw sensitive, 15 and joint movement, 12 units. 4. The forelimb representation within the ventrobasal thalamic complex was somatotopically organized, the over-all appearance being that of an incompletely closed fist, palmar surface uppermost, thumb media, with the wrist caudal and the digital tips rostral and dorsal. 5. The central projection was distorted, some parts showing expanded representation, notably the tips of digits II and III and the medial wrist pad. Other parts were contracted, e.g. the wrist, forearm and shoulder. 6. Units with receptive fields consisting of the whole of a walking pad had shorter mean latencies, to tactile stimulation, than those whose field was a single spot on a pad. 7. Units were found to show an abolute unresponsive time to the second of a pair of identical supramaximal electrical stimuli of up to 50 msec, and a relative unresponsive time which could last up to 500 msec. The absolute unresponsive and relative unresponsive times to the second of a pair of tactile stimuli was shorter being 30 and 150 msec respectively. 8. The effect of decortication was to increase the excitability of thalamic units to peripheral stimulation both in the initial and later discharges.

Action Potentials↗