Worldwide observations of remarkable deep-sea squids.
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Animals↗
Biomedical subjects
R E Young
Publications and source records attributed to R E Young.
A molecular phylogeny of the Octopoda (Mollusca: Cephalopoda) evaluated in light of morphological evidence.
In this paper we examine the phylogenetic relationships of the Octopoda utilizing molecular sequence data from the cytochrome c oxidase subunit I (COI) gene and compare results from analyses of molecular data with classifications and phylogenies based on previous morphological studies. Partial COI sequences (657 bp, excluding primers) were obtained from 28 species representing most of the diversity in the Order Octopoda, along with a sequence from the established sister taxon to the Octopoda, Vampyroteuthis infernalis. Our results exhibit a number of basic differences from inferences based on standard morphological data. We attempt to resolve these differences based on our confidence in various morphological features. An important finding is the failure of the molecular data to support the monophyly of the Octopodidae. This family contains over 90% of the species in the Suborder Incirrata and has always been difficult to define. Statistical tests constraining Octopodidae monophyly by use of parsimony and maximum-likelihood techniques suggest that all incirrates may be derived from octopodids.
Animals↗
Motor pathway analysis in HAM/TSP using magnetic stimulation and F-waves.
BACKGROUND: Tropical Spastic Paraparesis/HTLV-I Associated Myelopathy (HAM/TSP) is a chronic, progressive myelopathy endemic to the Caribbean. In HAM/TSP, peripheral motor pathways have been assessed using electromyography and nerve conduction studies; central motor pathways have been assessed to a limited extent using electrocortical stimulation. We used magnetic cortical stimulation (a painless alternative to electrocortical stimulation) and F-wave analysis to study conduction in the central and peripheral motor pathways in 18 HTLV-I seropositive, Jamaican TSP patients (ages 29-70 years; duration of symptoms 3-20 years) and 22 normal controls. METHODS: Magnetic cortical stimulation was effected using a 9 cm diameter undamped MES10 coil. F-waves and M-responses were elicited by electrical stimulation of the ulnar nerve at the wrist, and deep peroneal stimulation at the knee. Stimulation and recording of response latencies in abductor digitii minimi (ADM) and tibialis anterior (TA) were carried out using a Cadwell Excel system. RESULTS: With cortical stimulation, response latencies (TMCTs) to ADM and TA were prolonged in the patients relative to controls. F-wave and M-response latencies were unaffected, suggesting no peripheral pathology. Latency (CMCT) between cortex and lumbar cord was significantly prolonged; that between cortex and C7/T1, also, but less markedly (P < 0.0005). Amplitudes of cortically evoked responses were significantly reduced only in the lower limbs (TA). CMCT increased as the disease progressed from mild to moderate, thereafter remaining largely unchanged. CONCLUSIONS: Meta-analysis of interlaboratory control data revealed no significant differences in TMCTs between our controls and others studied using similar techniques. The observations are consistent with pathology affecting mainly the thoracolumbar cord in HAM/TSP.
Adult↗
Evolution of the Martian water cycle.
The current Martian water cycle is extremely asymmetric, with large amounts of vapor subliming off a permanent north polar water ice cap in northern summer, but with no apparent major source of water vapor in the southern hemisphere. Detailed simulations of this process with a three-dimensional circulation model indicate that the summertime interhemispheric exchange (Hadley cell) is very much stronger than transport by eddies in other seasons. As a result, water ice would be distributed globally were it not for the buffering action of regolith soil adsorption which limits the net flux of water vapor off the north polar cap to amounts that are insignificant even on the scale of thousands of years. It has been suggested that the polar layered deposits are the result of exchange on these long time scales, driven by changes in Martian orbital parameters. We therefore are conducting simulations to test the effect of varied orbital parameters on the Martian water cycle. We find that when the perihelion summer pole is charged with a polar water ice cap, large quantities of water are quickly transfered to the aphelion summer pole, setting up an annual cycle that resembles the present one. Thus, the adsorptivity of the Martian regolith may be in the narrow range where it can limit net transport from the aphelion but not the perihelion pole.
Adsorption↗
Galileo probe: in situ observations of Jupiter's atmosphere.
The Galileo probe performed the first in situ measurements of the atmosphere of Jupiter on 7 December 1995. The probe returned data until it reached a depth corresponding to an atmospheric pressure of approximately 24 bars. This report presents a brief overview of the origins and purpose of the mission. Science objectives, entry parameters and mission events, and results are described. The remaining reports address in more detail the individual experiments summarized here.
Ammonia↗
Disturbed anal sphincter function following vaginal delivery.
BACKGROUND: Recently interest in idiopathic (neurogenic) faecal incontinence has swung from denervation of the external anal sphincter to the internal sphincter. AIMS: To evaluate the effects of vaginal delivery on the internal sphincter. SUBJECTS: 1372 mothers were studied antenatally and 1202 were accepted into the study. METHODS: Sphincter pressures were measured antenatally, in the early postnatal period, and six to 10 weeks later in selected patients. RESULTS: 755 of 1202 subjects assessed antenatally were primiparous women and 447 multiparous women. Some 320 previous spontaneous vaginal deliveries (SVD) (mean 59 mm Hg) and 67 previous forceps deliveries (mean 58 mm Hg) had lower resting pressures than 755 primiparous women (mean 66 mm Hg) (p < 0.01). A total of 493 subjects were reassessed postnatally. There were 372 SVDs, 47 vacuum extractions, 20 forceps, and 54 caesarean deliveries. All vaginal deliveries but not caesarean sections dropped their resting anal pressures from antenatal values (p < 0.001). Some 227 first SVDs had a much greater fall than 145 subsequent SVDs. In 162 subjects who had undergone their first vaginal delivery and who were followed up there was some recovery but the resting pressures were still lowered at six to 10 weeks post partum. CONCLUSIONS: The first vaginal delivery causes a permanent lowering of resting anal pressures. The possible reasons for this are discussed.
Adolescent↗
Electrophysiological assessment of brain function in severe malnutrition.
Brain function in 10 severely malnourished children and matched controls was assessed using spectral analysis of electroencephalographic responses to photic driving during slow-wave sleep. The percentage power in the classical EEG broad-band domains was derived from temporo-occipital records. The malnourished group (5-23 months old; z-score height-for-age -3.2 +/- 0.3, weight-for-height -2.5 +/- 0.3) were tested on admission and on discharge from hospital. No significant differences were found between admission and discharge. Significant differences were found between malnourished and control groups, in the alpha 1 band in the undriven EEG, and in the alpha/beta 1 power ratio while driving at 8 Hz. These electrophysiological abnormalities, persisting despite somatic rehabilitation, must be associated with the chronic rather than the acute aspects of malnutrition, and can index the deviation of brain function from normality.
Body Height↗
Bioelectrical-impedance analysis as a measure of body composition in a West Indian population.
Percent body fat (%BF) was estimated in 50 males and 50 females aged 8-21 y by using hydrodensitometry (%BFd) and a bioelectrical-impedance analyzer (%BF-BIA). The sample population was racially heterogeneous, though predominantly of African origin. Percent body fat was computed from density by using an equation derived specifically for blacks. The BIA predicted %BF with r2 = 0.77 (SEE = 3.7%BF), underestimating by a mean of 1.7%BF. Residuals (%BFd - %BF-BIA) were normally distributed but were significantly correlated with age (P less than 0.01), although this effect was small. The theoretical bases for impedance analysis and for hydrodensitometry would appear for different reasons to impair applicability of these techniques to the present population and age group. However, for our population sample the BIA estimated %BF as precisely as other simple techniques applied to other populations.
Adipose Tissue↗
Antithyroid drugs in the treatment of hyperthyroidism of Graves' disease: long-term follow-up of 434 patients. Scottish Automated Follow-Up Register Group.
A study of antithyroid drug (ATD) therapy with a mean follow-up period of 10 years (range 2-25) in 434 patients with Graves' disease has been made by linking hospital records with those of a central follow-up register. The majority (89%) were treated with carbimazole and 87% received combined therapy with triiodothyronine (T3) (73%) or thyroxine (T4) (14%). Sixty-one per cent were assessed for T3 suppression tests on completion of treatment, of whom 61% (95% CL, 55-67%) suppressed. The overall 5-year cumulative proportion developing recurrent hyperthyroidism was 54-62% with rates of 26-44% in suppressed patients and 65-79% in those not suppressed. In unsuppressed patients, most (72%) of the recurrences occurred within 1 year with only an additional 10% predicted up to 10 years. In suppressed patients 30% of recurrences occurred in the first year, 60% between 1 and 5 years and a further 10% between 5 and 10 years. Suppression with T3 is probably the best and cheapest predictor of outcome but has an accuracy of only 70% for both positive and negative tests which limits its usefulness in planning long-term follow-up and surveillance. A standard format should be adopted for the analysis and reporting of follow-up studies, based on actuarial methods of estimating the cumulative proportion with recurrences or other events, to facilitate comparisons between different centres.
Adult↗
Photoreceptor evoked potentials and phototactic behaviour in Cercaria caribbea LXXI cable.
1. Transient potential changes evoked in response to light stimuli, and presumably arising from rhabdomeric eye-spots in the cercarial body, were recorded for the first time, to our knowledge, in helminth parasites. 2. Pigmented Cercaria caribbea LXXI gave a very slowly adapting response to maintained light stimulus, while a non-pigmented variety appeared to emit a stronger, rapidly adapting response to light onset. 3. Swimming towards a directional light source is disrupted by several neuropharmacological agents, which presumably disturb synaptic transmission in the nerve/muscle system. 4. The light evoked potentials were unaffected by these same agents and therefore, appeared to be directly recorded receptor potentials.
Animals↗
The effect of sub-lethal doses of dieldrin on the ventilatory and cardiac activity in two species of shrimps.
The effect of dieldrin on the heart and ventilatory activity in the shrimps Macrobranchium faustinum and Macrobrachium amazonicum was studied over 4 and 7 day exposure periods, respectively. In M. faustinum, ventilatory rate increased by 43% and heart rate by 14.4%. In M. amazonicum, the ventilatory and heart rates decreased by 21 and 6%, respectively. In M. amazonicum ventilatory reversal frequency, an index of respiratory stress, was 6.7 times higher than the control values. All the changes, except for M. amazonicum heart rate were significant at the 0.01 level of probability.
Animals↗
The effect of sub-lethal doses of dieldrin on resting and active metabolism in two species of shrimps.
The effects of dieldrin on the active (VaO2) and resting (VrO2) oxygen consumption rates of the shrimps Macrobrachium faustinum (De Sassure) and Macrobrachium amazonicum (Heller) were studied during exposure for 4 days at 0.01 p.p.b. and 7 days at 0.0002 p.p.b., respectively. The VrO2 of M. faustinum increased significantly (P less than 0.01) by 48% but the VaO2 decreased by 13%. The VrO2 and VaO2 decreased by 43 and 70%, respectively, in M. amazonicum. Thus, in both species the aerobic metabolic scope for activity decreased. The increased resting metabolic rate of the indigenous M. faustinum is ascribed to energy consuming responses which allow compensation for the effects of the stressor. The stressor may be said to have moved this species into a metabolic "zone of compensation". The decreased resting metabolic rate of the pond-cultured M. amazonicum is ascribed to greater susceptibility, more extensive metabolic breakdown and failure of compensatory responses. This species might be said to have been forced by the stressor into a metabolic "zone of collapse".
Animals↗
Ablative radioiodine therapy for hyperthyroidism: a long term follow up study.
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Follow-Up Studies↗
Mefenamic acid induced leucopenia in the elderly.
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Aged↗
Age and the daily dose of thyroxine replacement therapy for hypothyroidism.
The initial prescriptions and later adjustments of thyroxine (T4) replacement have been analysed in 2246 hypothyroid patients who have been monitored by a thyroid follow-up register for a mean period of 6 years (range 1-13 years). In 465 (21%) patients of 65 years or over, initial T4 doses were on average only 20 micrograms lower than in younger patients. However, only 40% of the elderly were taking 200 micrograms of T4/day or more, compared with 60% of the younger patients. Over 10 years, the predicted proportion of patients who have a downward adjustment of their T4 prescription is 3%, but there is no difference in recognized overtreatment between older and younger patients. The findings suggest that the majority of the elderly may receive larger doses of T4 than are required for optimal replacement. There are strong reasons for the standardization of thyroxine prescribing in the elderly and for the provision of routine surveillance of thyroxine replacement through the type of follow-up system used in this study.
Aged↗
Neural asymmetry in male fiddler crabs.
In adult male fiddler crabs, Uca pugnax, there is a marked enlargement of the 1st thoracic ganglion and its nerve root on the side of the major cheliped compared to the side of the minor cheliped. Retrograde uptake of cobalt via the cut ends of the motoneurons revealed a significant hypertrophy of their somata and dendritic fields on the major side of the ganglion compared to the minor side in the male fiddler crabs. (In female fiddler crabs which have two minor chelipeds the motoneurons were similar in size on both sides of the ganglion.) Since the number and distribution of motoneuron somata was relatively constant in the two halves of each ganglion, homologies for individual or groups of neurons could be recognized. The number of axon profiles in a cross-sectional montage of the entire nerve root of the major side in a male fiddler crab was several times greater than that of the minor side in random samples which were appropriately scaled in area. In samples of equal areas the axonal density was similar on the major and minor sides, as was also the range of axon diameters; both signify no difference in size of axons between the contralateral nerve roots. Consequently enlargement of the nerve root on the major side is due to a relative increase in the number of axons. This increase is in sensory fibers since the number of motor fibers are bilaterally constant. Thus neural asymmetry in male fiddler crabs involves hypertrophy of the motoneurons and hyperplasia of the sensory neurons associated with the enlarged condition of the major cheliped.
Animals↗
Which insulin for diabetic ketoacidosis?
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Animals↗