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Biomedical subjects

C Platt

Publications and source records attributed to C Platt.

At least 19 recordsLinked to original sources
PubMed2000

Structure and function in the saccule of the goldfish (Carassius auratus): a model of diversity in the non-amniote ear.

The vertebrate inner ear is comprised of a remarkable diversity of cell types, including several types of sensory hair cells. In amniotes (reptiles, birds, and mammals), the morphological and physiological characteristics that distinguish these cell types have been well documented, while cellular variation in the ears of non-amniotes (all other vertebrate groups) has remained underrecognized. Since non-amniotes have become increasingly popular models for developmental and genetic research, a more comprehensive understanding of structure and function in the inner ears of these species is warranted. This paper first reviews the large body of data describing the morphology and physiology of hair cells and afferent neurons in the inner ear of the goldfish (Carassius auratus). In particular, we examine the structure of the goldfish saccule, an endorgan that has been the subject of numerous investigations on audition. New data on the structural variation of synaptic bodies in saccular hair cells are also presented, and the functional implications of these data are discussed. Finally, we conclude that hair cell structure varies along the length of the goldfish saccule in a manner consistent with known physiological characteristics of the endorgan. The saccule provides an excellent model for investigating structure-function relationships in the vertebrate inner ear, as well as the development of auditory and vestibular sensory epithelia.

Animals↗
PubMed2000

Effect of a boil water notice on behaviour in the management of a water contamination incident.

In late 1998, the water supply of 878 households was affected by possible sewage contamination. A notice was issued to advise residents of the need to boil their water. This provided an opportunity to assess to what extent the boil water notice led people to avoid activities that might put them at risk of waterborne infection. A postal questionnaire sent to 350 randomly selected households in the affected area asked about timing and mode of receipt of the notice, risk behaviour (boiling water, brushing teeth, washing dishes, drinks for pets, preparation of food), and subsequent changes in drinking water consumption habits. Eighty-one per cent of the households surveyed engaged in behaviour likely to increase the risk of waterborne infection. Comments were collected from consumers on how to improve the management of future water contamination incidents.

Health Behavior↗
PubMed1999

Dysregulation of cyclin dependent kinase 6 expression in splenic marginal zone lymphoma through chromosome 7q translocations.

The increased or inappropriate expression of genes with oncogenic properties through specific chromosome translocations is an important event in the pathogenesis of B-cell lymphoproliferative diseases. Recent studies have found deletions or translocations of chromosome 7q to be the most common cytogenetic abnormality observed in SLVL, a leukemic variant of SMZL, with the q21-q22 region being most frequently affected. In three patients with translocations between chromosomes 2 and 7, the cloning of the breakpoints at 7q21 revealed that each was located within a small region of DNA 3.6 kb upstream of the transcription start site of cyclin dependent kinase 6 (CDK6). In each case the translocation event was consistent with aberrant VJ recombination between the immunoglobulin light chain region (Ig kappa) on chromosome 2p12 and DNA sequences at 7q21, resembling the heptamer recombination site. The t(7;21) breakpoint in an additional patient with splenic marginal zone lymphoma (SMZL), resided 66 kb telomeric to the t(2;7) breakpoints juxtaposing CDK6 to an uncharacterized transcript. In two of the SLVL patient samples, the CDK6 protein was found to be markedly over expressed. These results suggest that dysregulation of CDK6 gene expression contributes to the pathogenesis of SLVL and SMZL.

Aged↗
PubMed1999

Is universal screening for lead in children indicated? An analysis of lead results in Augusta, Georgia in 1997.

Pediatricians have a dilemma about whether they should do universal or targeted screening for lead in children. In order to determine whether we should continue our institution's present policy of universal screening, we analyzed 962 lead samples obtained by routine screening in the calendar year 1997, 83 children (8.6%) had elevated levels (over 10 mcg/dl) by capillary samples; of the 57 children who had follow up tests by venipuncture, 35 had abnormal levels making the incidence of elevated leads in our screened children 3.6%. Most of the abnormal levels were in African-American children living in two downtown zip codes. Based on recent AAP recommendations, in our community, targeted screening should replace universal screening.

Child↗
PubMed1996

Substance abuse and dependence in physicians: the Missouri Physicians' Health Program.

Substance abuse and dependence (alcohol and drugs) are behavioral disorders and treatable medical diseases. There is growing concern in the medical community for physicians impaired by these diseases. The Missouri Physicians' Health Program has been established to help impaired physicians return to healthy personal and professional lives. This confidential voluntary program of early referral, intervention, treatment, monitoring, and advocacy has been highly successful. The average recovery rate in this study of 146 participants was 94%.

Female↗
PubMed1993

Damage and regeneration of hair cell ciliary bundles in a fish ear following treatment with gentamicin.

Sensory hair cells in the striolar regions of the utricle and lagena of a teleost fish, the oscar (Astronotus ocellatus), were damaged following intramuscular injections of gentamicin sulfate. In order to determine whether fish can regenerate hair cells, the time course of damage and recovery was followed over a period of four weeks by scanning electron microscopy. Maximum loss of ciliary bundles occurred at about day 10 after the first of four daily injections of gentamicin (20 mg/kg) in 4-6 cm long fish. The striolar regions were almost totally denuded of ciliary bundles, and there was evidence of considerable hair cell loss. The time course for damage was longer in larger fish, but the recovery of the ciliary bundles appeared to be complete about 10 days after maximal damage was seen in both the smaller and larger fish. These data indicate that Astronotus is able to repair damage to hair cells for an extended period of time post-embryonically.

Analysis of Variance↗
PubMed1993

Zebrafish inner ear sensory surfaces are similar to those in goldfish.

The inner ear of the zebrafish (Brachydanio rerio) is very similar to that of the goldfish in its structural details, including the distribution and orientation of mechanosensory hair cell populations. Both species have been used in studying different aspects of the acoustic startle response. These structural similarities suggest that the zebrafish is a valid representative model for understanding peripheral hearing specializations in otophysan fishes.

Acoustic Stimulation↗
PubMed1990

An experiment in psychiatric community care in north Staffordshire: the experience of working with relatives of mentally-ill people.

This paper describes the changing nature of the relationship between the consumers and providers of services, following the transition from a hospital to a community-based service. One aspect of this change, the development of a relatives' group, is considered in more detail. Those attitudes and approaches which help or hinder staff working with relatives are discussed.

Adaptation, Psychological↗
PubMed1988

Early abrupt recovery from ataxia during vestibular compensation in goldfish.

1. Vestibular compensation was studied in goldfish that had had the utriculus and semicircular canal organs unilaterally removed. Characteristic postoperative behavioural deficits of postural asymmetry were quantitatively scored. Operated animals were compared with those subject to the same duration of anaesthesia and restraint during a sham operation. 2. The period of several minutes following the operation was characterized by severe postural asymmetry and locomotor ataxia. In the operated fish, but not the sham-operated ones, the eyes rolled tonically towards the operated side without nystagmus, the body was flexed towards the operated side, and any swimming was disoriented with rolling motion towards the operated side. These deficits lasted less than 30 min after revival from the anaesthesia. All three behavioral deficits ended abruptly within 1 min of each other for individual fish, and normal, nearly upright swimming was then maintained, even in the dark. 3. We interpret this recovery as one of the first stages in the central process of vestibular compensation. The unusually abrupt end of these deficits in adult goldfish compared with that in other vertebrates suggests a remarkable capacity for the central nervous system to adapt. The speed of recovery of three distinct motor outputs supports models of early compensation that utilize central modulation or gain control of existing pathways, rather than anatomical reorganization.

Animals↗
PubMed1988

Postural changes occurring during one month of vestibular compensation in goldfish.

1. Postural behavioural changes during vestibular compensation were studied in goldfish. The tilting posture induced by directional light in the dorsal light reflex (DLR) was monitored by an automated camera system. Responses were measured over a 1-month period following a partial unilateral labyrinthectomy. 2. After the fish had recovered from the ataxic stage, the first observable DLR had shifted strongly towards the operated side. This early bias decreased rapidly, then more gradually. Mean values for the DLR reached a steady state within 2 weeks. 3. Recovery rates were slowest for DLR tilts elicited by light presented from the operated side. 4. The DLR did not recover to preoperative control values for light from either the intact or operated side. Shortly after the operation, light from the operated side produced DLR values nearly double the normal; light from the intact side had an effect very little different from normal. At steady state, the light effect from the operated side had decreased from the high immediately post-ataxic levels to a level roughly 1.5 times normal, but the light effect from the intact side had increased, also reaching a level roughly 1.5 times normal. Thus the final values again show symmetry. 5. Variability appears to be an important feature of the response.

Animals↗
PubMed1987

Anatomy and differential growth of the lateral line system of the mottled sculpin, Cottus bairdi (Scorpaeniformes: Cottidae).

Scanning electron microscopy and standard histological techniques were used to describe the basic anatomy and postembryonic growth of the lateral line system of Cottus bairdi. The gross anatomy and distribution of lateral line neuromasts in canals and superficially on the skin are similar to what has been reported for many primitive actinopterygian fishes. Both canal and superficial neuromasts showed postembryonic growth in the number of hair cells and size of neuromasts, but canal neuromasts grew more elongate whereas superficial neuromast grew symmetrically. Neuromasts in the mandibular canal grew significantly faster than any other neuromasts and superficial neuromasts on the head showed the least amount of growth. Differential growth of the sculpin lateral line system may be related to the feeding behavior of the animal and to differences in the ambient levels of water noise to which larval and adult fish are exposed.

Animals↗
PubMed1986

Social class, underprivileged areas and psychiatric disorder in the city of Stoke-on-Trent.

A survey of psychiatric disorder, based on hospital inpatient records, was conducted in the City of Stoke-on-Trent, England for the year 1983. This was used to test the hypothesis that areas of lower social class and greatest underprivilege would display higher rates of inpatient admissions for psychiatric disorder than the more privileged areas of the city. The results confirmed a significant positive correlation between extent of underprivilege of an area and rates of inpatient admissions. The link between lower social class and mental disorder was not directly demonstrated.

England↗
PubMed1984

Variation in lengths of ciliary bundles on hair cells along the macula of the sacculus in two species of teleost fishes.

The sacculus is one of the end-organs of the inner ear. In many teleost fishes the sacculus is considered the major auditory organ. We have used scanning electron microscopy to examine the lengths of the ciliary bundles on hair cells in the sensory macula of the sacculus in two diverse species of teleosts. The data are presented in a form allowing direct comparison with recent data on a wide range of tetrapod auditory organs. In goldfish, the ciliary bundles are significantly longer in the caudal part of the macula than in the rostral part, but the kissing gourami shows nearly uniform ciliary bundle heights along its entire length. Based on limited data from the literature, the part of the macula responsive to lower frequencies is the part containing these taller bundles in goldfish, suggesting a parallel with the gradient of ciliary bundles and frequency response found in tetrapods.

Animals↗
PubMed1983

Retention of generalized hair cell patterns in the inner ear of the primitive flatfish Psettodes.

Flatfish are a group of uniquely asymmetrical vertebrates, lying always on one side. This postural control depends on the vestibular receptors of the inner ear. From the most primitive living flatfish, orientations of sensory hair cells in the inner ear were mapped by scanning electron microscopy. The maps of the three otolith organs, the three semicircular cristae, and the macula neglecta (newly discovered here for flatfish) show patterns that are very similar to those in many upright teleosts, particularly perches. Thus, peripheral sensory structure does not require modification for the unusual postural control of flatfish.

Animals↗
PubMed1977

Hair cell distribution and orientation in goldfish otolith organs.

Structurally diverse sensory regions occur in the otolith organs of the goldfish inner ear. Scanning electron microscopy reveals regional distinctions based on three criteria. (1) Hair cells have different sizes of apical bundles, based on thickness. In all three maculae, two central regions have hair cells with bundles significantly thicker than those in surrounding regions. (2) Hair cell population density varies, with regional aggregations present. The central regions with thick bundles have two to three times the density of surrounding regions with thin bundles, and contain 40-80% of the total hair cell number in each macula. (3) Hair cell orientation maps show that each macula has two oppositely oriented cell populations that can be separated completely, not by a zone of interspersion, but apparently by a single unbroken line. The lagena is like the utricle in having hair cells with the kinocilium on the side of the cell toward the opposition line, but in the saccule the kinocilia face away from the line, and the small macula neglecta consists of two completely separate, oppositely oriented patches. The opposition line does not divide each macula simply down its midline; instead, the line divides the regions with thich bundles into nearly equal opposing areas, except for a remarkably abrupt large loop in the line in the anterior part of the saccule. The regional structural diversity in these organs may relate to localized functional diversity of responses to tilt, vibration and sound.

Animals↗