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Biomedical subjects

E A Shaw

Publications and source records attributed to E A Shaw.

At least 19 recordsLinked to original sources
PubMed1989

Anaesthetic induction in children: the effects of maternal presence on mood and subsequent behaviour.

Forty-nine children, aged from 1 to 9 years, undergoing elective surgery under general anaesthesia, were studied in two groups. In one group, each child's mother was present during induction of anaesthesia, whereas in the other group no parent was present. Children's moods and cooperation during waiting and induction periods did not differ significantly between the groups, neither was the incidence of technical difficulties with anaesthetic induction different. Induction took longer (P = 0.005) if the mother was present. Mothers, when present, were calm and supportive to their children, with one exception. No mother was critical or interfering. Each child's behaviour was assessed by questionnaire pre-operatively and 4 weeks post-operatively. There was a significant overall improvement in behaviour scores post-operatively. There were no significant differences in direction or magnitude of behaviour changes between the two groups.

Affect↗
PubMed1988

Comparison of atracurium-induced neuromuscular blockade in neonates, infants and children.

The potency of atracurium was determined in neonates, infants and children during thiopentone-fentanyl-nitrous oxide in oxygen anaesthesia using single dose-response curves. The effective doses producing 50% depression of the first twitch of the train-of-four were significantly lower in neonates and infants than in children (82 and 112 v. 135 micrograms kg-1). Following a standard dose of atracurium 0.5 mg kg-1, 95% depression of the first twitch occurred more rapidly in neonates than in children (0.9 v. 1.4 min), while recovery to 10% of the control twitch height occurred more rapidly in neonates than in the other two groups (22.7 v. 29.7 and 28.6 min). It is concluded that neonates and infants require less atracurium to produce a given degree of neuromuscular blockade compared with older children. However, prompt recovery can be expected in all healthy paediatric patients following a standard intubating dose of atracurium 0.5 mg kg-1.

Anesthesia, General↗
PubMed1985

Transformation of sound-pressure level from the free field to the eardrum presented in numerical form.

In an earlier work [E. A. G. Shaw, J. Acoust. Soc. Am. 56, 1848-1861 (1974)], self-consistent families of curves which best fitted the experimental data from 12 studies were presented to show the average sound-pressure transformation from the free field to the human eardrum in the horizontal plane. Tabulated values of azimuthal dependence at 15-deg intervals in azimuth and transformation to the eardrum at 0 degree azimuth are given at 43 selected frequencies between 0.2 and 12 kHz. These values are self-consistent within 0.1 dB.

Humans↗
PubMed1985

Abnormal thyroid hormone binding to serum proteins in ob/ob and db/db genetically obese mice.

Sera from ob/ob and db/db genetically obese mice exhibited abnormal nonspecific (no antibody present) binding measurements in T4 and T3 RIAs employing dextran-charcoal separations. They also showed decreased charcoal uptake compared to sera of lean controls in a conventional charcoal T4 uptake binding test. After correction for the abnormal nonspecific binding and after extraction of serum, mean serum T4 concentrations were similar in control and ob/ob mice. Mean serum T3 concentrations differed significantly (85 ng/dl in controls and 178 ng/dl in ob/ob) when a correction for altered binding in the T3 assay was made, but not when extracted serum was assayed (109 ng/dl in lean and 124 ng/dl in ob/ob). Dialyzable fractions of T4 and T3 were significantly reduced in both ob/ob and db/db mice. Free T4 concentrations were 0.82 +/- 0.05 (+/- SE) ng/dl in control and 0.61 +/- 0.05 ng/dl in ob/ob sera (P less than 0.01). Polyacrylamide gel electrophoresis showed increased binding of tracer T4 and T3 in ob/ob and db/db sera to a postalbumin with mobility similar to that of human T4-binding globulin. In ob/ob sera, this appeared to result from an increased binding capacity of the postalbumin. After in vivo iv injection of tracer T4 and T3 to ob/ob and lean control mice, analysis of tissue and plasma radioactivity showed that, except for T4 in cerebral cortex, tissue to plasma T4 and T3 ratios were lower in cerebral cortex, cerebellum, and liver of ob/ob mice. In summary, these data show increased binding of T4 and T3 to a postalbumin in two strains of genetically obese mice and, in the ob/ob strain, complex relationships between tissue and serum concentrations of thyroid hormones.

Animals↗
PubMed1984

Iodothyronine deiodination reaction types in several rat tissues: effects of age, thyroid status, and glucocorticoid treatment.

Two types of iodothyronine 5'-deiodination have been characterized previously in rat tissues. They can be distinguished by inhibition of type I but not type II by 6-n-propylthiouracil, by the relative suitability of T4 and rT3 as substrates, rT3 much better than T4 for type I and T4 as good as, or better than, rT3 for type II, and by the concentration of T4 required to inhibit deiodination of rT3, 1-10 microM for type I and 1-10 nM for type II. Type I activity (6-n-propylthiouracil sensitive) is most abundant in liver and kidney. Type II activity has, to date, been identified only in the pituitary, central nervous system, and brown adipose tissue. Iodothyronine tyrosyl deiodination has also been identified in homogenates of rat brain, liver, and placenta. It is not clear how many different enzymes carry out this latter reaction. In the present studies, we have extended previous work by determining maturational patterns of the deiodinating pathways in several thyroid hormone-responsive rat tissues, possible modulation of those patterns by glucocorticoids, and the age of onset of responsivity of the deiodinases to hypothyroidism. Iodothyronine 5'-deiodinating activity was found in rat lung and eye, and the reaction was all or nearly all type I in both. Activity in the eye was virtually absent from the lens and vitreous humor. In immature rat cerebrum, pituitary, lung, and eye, between gestational day 17 and postnatal day 21, there was a uniform pattern of an increase in type I 5'-deiodination activity over time, until adult levels were attained. The ages at which adult activity levels were reached varied from tissue to tissue, however. Type II activity was present at the earliest ages tested in the cerebrum (gestational day 17), pituitary, and brown adipose tissue (day of birth). In cerebral cortex, type II activity was highest at day 21 postnatally and equal at birth and in adulthood, and in pituitary and brown adipose tissue it was higher in adulthood than at birth. T3 tyrosyl ring deiodinating activity was several times greater in homogenates of eye and placenta than in cerebral homogenates. In all three tissues, there was similar, dose-dependent inhibition of [125I]T3 tyrosyl deiodination by 5 nM and 20 nM nonradioactive T3. In the eye and brain, T3 tyrosyl deiodination rates decreased progressively with age from gestational day 17 to postnatal day 7.(ABSTRACT TRUNCATED AT 400 WORDS)

Adipose Tissue, Brown↗
PubMed1984

Type II iodothyronine 5'-deiodination by human and rat placenta in vitro.

T4 and rT3 5'-deiodination were measured in human and rat placental homogenates. rT3 5'-deiodination rates were reduced 5-40% by 1 mM 6-n-propylthiouracil (PTU), but T4 5'-deiodination was not affected by 1 mM PTU. In human tissue, homogenates of the chorionic membrane decidua had greater PTU-insensitive activity than homogenates of trophoblastic tissue or amnion. In the rat placenta, basal zone homogenates had greater activity than homogenates of placental labyrinth or amnion. The distribution of 5'-deiodinating activity in placental structures differed from that of T3 tyrosyl ring deiodinating activity in both species. PTU-insensitive rT3 5'-deiodinating activity was enriched in particulate subcellular fractions, but not in cytosol. Kinetic studies of T4 5'-deiodination using particulate fractions from human chorionic membrane decidua and rat basal zone showed a sequential kinetic pattern when the dithiothreitol concentration was varied, with apparent Michaelis constants (Km) and 50% inhibitory concentrations for T4 of 2.1-3.2 nM, and for rT3 of 9-15 nM. Thus, PTU-insensitive iodothyronine 5'-deiodination in rat and human placenta is very similar to, or the same as, that termed type II activity in rat anterior pituitary, central nervous system, and brown adipose tissue. These results extend the range of tissues in which type II iodothyronine 5'-deiodination has been identified, and strengthen the applicability to man of studies of iodothyronine deiodination in the rat.

Animals↗
PubMed1982

Estimation of acoustical energy reflectance at the eardrum from measurements of pressure distribution in the human ear canal.

At frequencies greater than 2 kHz the acoustic impedance at the human eardrum is an unreliable indicator of the behavior of the middle ear system because of the complicated configuration of the ear canal and tympanic membrane. The energy reflectance at the eardrum, however, when obtained from measurement of the standing wave ratio (SWR) in the canal, is relatively insensitive to irregularities in the anatomical layout at the higher frequencies. Measurements of sound pressure distribution in 13 normal ear canals have been analyzed in a critical manner to provide new values of SWR, with estimates of error, between 5 and 10 kHz. At the higher frequencies these values tend to be appreciably greater than those previously reported. At 8 kHz, for example, the new values of SWR range between 18 and 24 dB as compared with earlier values which are in the vicinity of 13 dB. The correspondingly greater values of energy reflectance (60%-78%, as compared with 40%) are more consistent with known properties (mass, size, vibrational patterns) of the human eardrum. These results are applicable to the development of network models representing the middle ear system.

Acoustic Stimulation↗
PubMed1971

Airway obstruction.

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Airway Obstruction↗