Michael C. R. Davies

Promoting the psychological well-being of refugee children

Meeting the mental health needs of Somali refugee children in Wales creates significant difficulties for service provision. Some case examples are provided. The children’s needs, the services received and the plight of refugee children are discussed in the context of the following key areas: (i) the child (aspects of development); (ii) the referred problem; (iii) the war/refugee context; (iv) Somali culture; and (v) the host culture. Developmental factors relating to the vulnerability of refugee boys in the host culture are identified. Based on their experiences and with the benefit of recent literature, the authors recommend a coordinated and culturally sensitive approach to the care of refugee children and their families.

Effects of 5-hydroxytryptamine agonists and antagonists on the responses of rat spinal motoneurones to raphe obscurus stimulation

1 The excitability of lumbar spinal motoneurones was studied in halothane‐anaesthetized rats by recording with microelectrodes the amplitude of the population spike evoked antidromically by stimulation of the cut ventral roots. 2 Electrical stimulation of the nucleus raphe obscurus for 1 min at 20 Hz increased the population spike amplitude and, as shown by intracellular recording, depolarized motoneurones. This response could be mimicked by microinjection of dl‐homocysteic acid into raphe obscurus but the response was not present in animals pretreated wtih the 5‐hydroxytryptamine (5‐HT) neurotoxin 5,7‐dihydroxytryptamine (5,7‐DHT). 3 Microiontophoretically applied 5‐HT had very similar effects on the extracellularly recorded population spike to those caused by stimulation of the raphe obscurus. These responses to 5‐HT were larger in 5,7‐DHT‐pretreated animals. 4 The effects of 5‐HT were potently mimicked by iontophoretically applied 5‐carboxamidotryptamine but 8‐hydroxy‐2‐(di‐n‐propylamino) tetralin (8‐OH‐DPAT) was without effect. 5 Antagonists were applied by microiontophoresis and also by intravenous injection. Ketanserin, the selective 5‐HT2 antagonist, did not antagonize the effects of 5‐HT. Neither did the 5‐HT3‐receptor antagonist MDL 72222 or the selective 5‐HT1 binding ligand cyanopindolol. 6 The non‐selective 5‐HT1/5‐HT2‐receptor antagonist methysergide was an effective antagonist of both the effects of 5‐HT and the response to raphe obscurus stimulation. Methysergide did not reduce the excitatory effects of noradrenaline. 7 It is concluded that 5‐HT application and stimulation of raphe obscurus increase the excitability of motoneurones by an action on a 5‐HT1‐like receptor which appears to be different from the 5‐HT1A‐and the 5‐HT1B‐binding sites characterized by others.

Evidence for excitatory 5‐HT2‐receptors on rat brainstem neurones

1 The technique of microiontophoresis was used to investigate the identity of the receptor mediating the excitatory effects of 5‐hydroxytryptamine (5‐HT) upon neurones in the midline of the medullary brainstem of the rat in vivo. 2 The 5‐HT1‐like receptor agonists 5‐carboxamidotryptamine (5‐CT) and 8‐hydroxy‐2‐(di‐n‐propylamino) tetralin (8‐OH‐DPAT) failed to excite the majority of neurones excited by 5‐HT. The mobilities of 5‐CT and 8‐OH‐DPAT when tested in vitro were found not to differ significantly from that of 5‐HT, suggesting that the lack of effect of these agonists was not due to a lower rate of release from the microelectrodes. 3 The excitatory responses to 5‐HT were attenuated by the 5‐HT2‐receptor antagonists ketanserin and methysergide when applied microiontophoretically or administered intravenously (0.3 and 1 mg kg−1 respectively). Excitatory responses to glutamate and noradrenaline were not reduced. 4 The 5‐HT3‐receptor antagonist MDL 72222 failed to attenuate selectively the excitatory response to 5‐HT when applied either by microiontophoresis or administered intravenously (1 mg kg−1). 5 Microiontophoretic application of the α1‐adrenoceptor antagonist prazosin did not attenuate excitatory responses to either 5‐HT or noradrenaline. Intravenously administered prazosin (0.8 mg kg−1) also failed to attenuate excitatory responses to 5‐HT, but did block excitatory responses to noradrenaline. 6 These results suggest that 5‐HT2‐receptors, but not 5‐HT1‐like receptors, 5‐HT3‐receptors or α1‐adrenoceptors, are involved in the excitatory response of midline medullary neurones to 5‐HT.

Rates and processes of periglacial solifluction: an experimental approach

Cold room physical modelling of periglacial solifluction processes on an experimental slope of 12° is described, and data on soil temperatures, surface frost heave, thaw consolidation, downslope soil movement and porewater pressures over seven freeze–thaw cycles are presented. These data are analyzed in the context of laboratory determination of the rheometry of the experimental soils at high moisture contents. It is concluded that the observed thaw-induced solifluction represents pre-failure soil shear strain and results from loss of strength due to the combined effects of raised porewater pressures during thaw consolidation and upward seepage pressures as water flows towards the surface away from the thaw front. An investigation of the rheometry of thawing soils offers the prospect of an analytical model to predict rates and depths of periglacial solifluction.

Interactions of Carbenicillin and Ticarcillin with Gentamicin

The in vitro inactivation of gentamicin by carbenicillin and a new semisynthetic penicillin, ticarcillin (BRL 2288), has been demonstrated. Gentamicin half-lives have been studied in eight patients with end-stage renal failure, and a 25 to 74% reduction in half-life has resulted from the concomitant administration of therapeutic doses of carbenicillin and ticarcillin.

Gelifluction: observations from large-scale laboratory simulations.

Despite extensive field studies, progress in understanding gelifluction processes has been limited. Controlled laboratory simulation experiments offer an alternative and potentially extremely effective approach. Such an experiment is described here. It was conducted on a 12° slope formed of two natural soils, one a fine sandy silt derived from slate bedrock, the second a gravelly silty sand derived from mudstone bedrock. Continuous measurements were made of soil temperatures, porewater pressures, frost heave, thaw settlement, and downslope displacements of the soil surface over seven freeze/thaw cycles. Two-dimensional vectors of soil surface movements together with evidence from excavated displacement columns suggest that gelifluction occurred only during thaw consolidation of the upper parts of the soil profile; thawing of the deeper layers caused thaw consolidation but little downslope displacement. Cryogenic processes are shown to cause progressive decreases with depth in void ratio and moisture content and increases in undrained shear strength within the continuous soil matrix that separates ice lenses. Since self-weight stress levels are low, thawing leads to significant shear strain only in the softer, wetter near-surface soil layers.

Laboratory measurement of the shear strength of ice-filled rock joints

Abstract To assess the safety against failure of rock slopes in cold regions, such as high mountain areas, where stability is potentially maintained by ice in rock discontinuities, the shear strength of ice-filled rock joints was investigated in a series of direct shear-box tests. To permit control and repeatability, the experiments were conducted using simulated rock specimens. These were cast in the laboratory using high-strength concrete. Laboratory measurements showed that at a constant rate of shearing, the interface shear strength between ice and a joint surface of repeatable roughness is a function of both temperature and normal stress.

Evidence for depressant 5‐HT1‐like receptors on rat brainstem neurones

1 The technique of microiontophoresis was used to evaluate the contribution of 5‐HT1‐like, 5‐HT2‐ and 5‐HT3‐receptors to the depressant effects of 5‐hydroxytryptamine (5‐HT) on neurones in the midline of the medullary brainstem of the rat in vivo. 2 Depressant responses to 5‐HT were resistant to antagonism by the 5‐HT2‐receptor antagonist ketanserin and the 5‐HT3‐receptor antagonist MDL 72222 applied either microiontophoretically or administered systemically. 3 Microiontophoretic or systemic administration of the 5‐HT antagonist metergoline, which shows nanomolar affinity for the 5‐HT1‐binding site, also failed to attenuate the depressant responses to 5‐HT. 4 Systemic administration of high doses of methysergide (30–40 mg kg−1) attenuated the depressant responses to 5‐HT but did not block depressant responses to GABA or excitatory responses to glutamate. 5 The depressant effects of 5‐HT were potently mimicked by the 5‐HT1‐like receptor agonists 5‐carboxamidotryptamine and 8‐OH‐DPAT. 6 These results indicate that neither 5‐HT2‐receptors nor 5‐HT3‐receptors are involved in the depressant effects of 5‐HT on midline brainstem neurones. The depressant effects of 5‐carboxamidotryptamine (5‐CT) and 8‐hydroxy‐2‐(di‐n‐propylamino) tetralin (8‐OH‐DPAT) and blockade of the response to 5‐HT by high doses of methysergide suggests the involvement of 5‐HT1‐like receptors. The lack of effect of metergoline, however, indicates that this receptor may be different from any of the 5‐HT1 binding sites yet described.

An experimental design for laboratory simulation of periglacial solifluction processes

An experimental slope of gradient 12° was constructed, comprising two 5 m × 2 m × 0·3 m contiguous strips of natural soils. Soil freezing and thawing took place from the surface downwards in an open hydraulic system, water being supplied at the base of each soil. Thermal conditions, porewater pressures and soil displacements were monitored using a PC-based logging system, with readings taken at half-hourly intervals. Soil surface displacements due to frost heave and solifluction were measured using linear voltage displacement transducers. Soil temperatures were determined using thermistors and semiconductor temperature sensors. Antifreeze-filled miniature ceramic-tipped pressure transducers were used to determine porewater pressure variations. The potential of this experimental approach for precise monitoring of mass movement processes associated with thawing of ice-rich soils is demonstrated.

Constructing Mental Health Services for Looked after Children

Recent years have seen a welcome series of government measures aimed at meeting the mental health needs of looked after children. However, as Eddy Street and Mike Davies argue in this paper, there remains a clear lack of integration of models of ‘good practice’ among childcare and mental health professionals. Taking into consideration the ‘tiered model’ recommended by the NHS Health Advisory Service report (1995), the authors advocate a developmental approach through the implementation of a multi-disciplinary service that combines the best of psychiatric, psychological, social work and childcare perspectives.