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Biomedical subjects

A Davis

Publications and source records attributed to A Davis.

At least 235 records · Page 13Linked to original sources
PubMed1993

The feasibility of evoked otoacoustic emissions as an in-patient hearing check after meningitis.

The desirability of finding children with hearing impairment after bacterial meningitis as soon as possible prompted us to examine the feasibility of using evoked otoacoustic emissions (EOAE) as an in-patient check of hearing status in children recovering from bacterial meningitis. Sixty-six episodes of bacterial meningitis were studied. Traces could be recorded for only 54.7% of ears. All children subsequently found to have sensorineural hearing impairment who were tested with EOAE, failed the screening test. The low coverage of the screening test and the predicted low specificity due to the high incidence of conductive hearing impairments, lead us to conclude that, with the technology currently available, the measurement of EOAE after bacterial meningitis is not a practical method for a pre-discharge check of hearing. Every effort must still be made to ensure all children are referred for an appropriate auditory assessment.

Adolescent↗
PubMed1993

Hearing impairment in children after bacterial meningitis: incidence and resource implications.

A retrospective review over ten years of childhood cases of bacterial meningitis treated in two hospitals in Nottingham revealed 301 cases: 88.4% of these children survived. The audiological and clinical hospital records of the survivors were examined to see if the children had been assessed for hearing impairment following the illness. Results indicate that 202/261 (77.4%) of the survivors remaining in the local area had had a formal hearing assessment. Fifteen of these children (7.4% of those assessed) suffered some degree of sensorineural or mixed hearing loss as a direct consequence of meningitis. The impairments ranged from mild unilateral to profound bilateral and the affected children were aged between 0 (i.e. infection at birth) to 15 years. The data indicate that bacterial meningitis of any type can result in sensorineural hearing impairment of any degree in a child of any age. A significantly increased risk of hearing impairment was found for children aged less than one month or over 5 years, for children with associated hydrocephalus, for children admitted between October and March, for those in hospital longer than 16 days and for those with a cerebro-spinal fluid glucose concentration of < or = 2.2 mmol/l. No differential increased risk was noted for different causative pathogens. Abnormal tympanograms indicative of conductive hearing impairment were measured at the first visit in 45% of children attending for hearing assessment. These conductive losses resolved in 75% of cases. These data suggest that an English health district, with a total population of 250,000, would need to provide annual resources for about 30-40 appointments for children after meningitis. Over a period of 5 years it might provide hearing aids for three children and a cochlear implant for one child. Bacterial meningitis is the single most important cause of acquired sensorineural hearing impairment in children and every attempt should be made to assess the child's hearing as soon after recovery as possible.

Acoustic Impedance Tests↗
PubMed1993

Cloning of cDNAs encoding the alpha and beta subunits of rat casein kinase 2 (CK-2): investigation of molecular regulation of CK-2 by androgens in rat ventral prostate.

Casein kinase 2 (CK-2) is a ubiquitous messenger-independent protein serine/threonine kinase that has been implicated in the control of cell growth and proliferation. By employing androgen action in the prostate as a model of growth control, we have previously documented that androgens modulate prostatic CK-2 activity in a tissue specific manner. Here we have investigated the role of transcriptional control of prostatic CK-2 in androgenic regulation of its activity. We first cloned and sequenced full length cDNAs encoding the alpha and beta subunits of rat CK-2. The cDNA sequence encoding the alpha subunit corresponded with previously reported sequences for other species, as well as with the derived partial amino acid sequence reported for a rat cDNA. The cloned cDNA for rat CK-2-beta subunit, not reported previously, was also identical in amino acid sequence to that of other species. The cDNAs for alpha and beta subunits were employed as probes to examine the effects of altered androgenic status on transcription of mRNAs for the subunits of prostatic CK-2. Androgen deprivation caused a slow decline in transcription of the a subunit, so that no change was noted at 24 h postcastration; however, at later periods of androgen deprivation a progressive but relatively slow decline was apparent. Administration of a single dose of 5 alpha-dihydrotestosterone (5 alpha-DHT) to 6-d castrated animals did not elicit an early expression of new mRNAs for CK-2-alpha and beta subunits. However, a significant expression of mRNAs for the two subunits was apparent at 8 h (i.e., later stages of the prereplicative phase) reaching a peak in the proliferative phase of prostatic growth (i.e., at 24-48 h) following androgen administration. These data suggest that androgenic regulation of CK-2 gene transcription is not an early event related to androgen action, but is substantial in the prereplicative phase of prostatic cell proliferation mediated by androgen. Further, androgenic stimulation of the mRNA expression for the alpha and beta subunits of CK-2 appears to be differential.

Amino Acid Sequence↗
PubMed1993

Standardizing the clinical content of a third-year family medicine clerkship.

BACKGROUND: The increasing presence of family medicine as a required clinical experience during medical school has created a need to provide quality experiences for a large number of students. Use of community private practices is one way to address this need. An important issue with this approach is standardization of clinical content among diverse teaching sites. This paper investigates whether students on required one-month family medicine clerkships occurring at university and private practice sites obtain comparable experiences. METHODS: The experiences of 185 third-year medical students were compared in the following areas: patient volume, patient mix, and performance on end-of-clerkship oral and written examinations. RESULTS: Of the 20 core problems seen most frequently by students, four were seen by significantly different numbers of university and private practice students overall; only two remained significantly different when analysis was restricted to the second half of the reporting period. Differences between the number of university and private practice students seeing the minimum targeted number of patients per session were nonsignificant (P = .895), as were differences between the two groups' oral and written examination scores (P = .507 and P = .595, respectively). CONCLUSIONS: We found that clinical content of a required third-year clerkship could be successfully standardized, as measured by patient volume, mix, and student performance on examinations.

Clinical Clerkship↗
PubMed1993

[Fresh osteochondral transplants in the treatment of advanced giant cell tumors].

Eighteen patients with advanced giant cell tumors were treated with complete tumor resection and reconstruction using fresh osteochondral allografts. All patients had one or more of the following indications for tumor resection (as opposed to curettage): tumor recurrence, pathological fracture, or destruction of the subchondral bone plate. At the 4- to 16-year follow-up (mean 9 years), two grafts were revised to a second fresh graft because of fracture, one graft was converted to an allograft implant composite and two joints were fused because of infection. The functional results were assessed in 14 patients: 9 were good or excellent, 4 fair and 1 poor. We conclude that the fresh osteochondral allograft is a viable treatment alternative to prosthetic replacement in advanced benign, aggressive bone tumors.

Adult↗
PubMed1993

Increasing inter-rater agreement on a family medicine clerkship oral examination--a pilot study.

BACKGROUND AND OBJECTIVES: Although oral examinations are a traditional measure of student performance during clinical clerkships, concerns have been expressed about poor inter-rater reliability on these examinations. This study examines inter-rater agreement in a family medicine clerkship oral examination. METHODS: Our study analyzed oral examination scores awarded to a class of 98 junior medical students by three categories of examiner (the clerkship director, full-time faculty, and third-year residents). For each student, the difference among the three examiners' raw scores was compared using a Cronbach statistic. Mean scores for the year awarded by each of the three groups of examiners were compared using a correlation coefficient and paired t tests. For students with high inter-rater disagreement, examiner narrative comments and types of questions on which raters disagreed were analyzed. RESULTS: Overall inter-rater agreement was high (Cronbach's alpha = .875). Paired t tests were nonsignificant between residents and faculty but were significant between residents and the clerkship director and between faculty and the clerkship director. In the small subset of students with little inter-rater agreement, no clear trends were identified to explain reasons for evaluator disagreement. CONCLUSION: High levels of inter-rater agreement on a clerkship oral examination can occur when several measures to increase inter-rater agreement are used.

Adult↗
PubMed1992

Genetic manipulation of the mouse via gene targeting in embryonic stem cells.

Gene targeting applied to totipotent embryonic stem (ES) cells is a very powerful means of creating highly specific mutations of genes in the mouse. The successful application of this technology is however constrained by both the types of mutations that can be generated at a target locus and the ability to reconstruct a germline chimera from the manipulated cells. We have developed two cell lines that can be routinely transmitted through the germline of chimeras after cloning and prolonged selection in tissue culture. We have also established a variety of methods for generating non-selected mutations at the X-linked hprt locus in ES cells. Our observations at this locus have enabled us to generate successfully a subtle mutation at the non-selectable Hox-2.6 locus.

Animals↗
PubMed1992

Prepubertal initiation of sexual experiences and older first partner predict promiscuous sexual behavior of delinquent adolescent males--unrecognized child abuse?

Sexual experiences of 1580 delinquent adolescent males ages 9-19 years admitted to a juvenile detention center from January 1985 to July 1990 were determined through a structured health history interview. A total of 89.6% admitted to prior sexual activity; 26.8% claimed sexual experience by age 11 years. Only 3.2% reported sexual abuse or incest. Of 334 sexually active adolescents who revealed both age of their first partner and their age of first intercourse, 42% had their first experience with a female 2 or more years older. Males who had their first sexual experience before age 11 years or with a female 2 or more years older, reported significantly larger numbers of sexual partners in their lifetime and during the year preceding their incarceration. Girls with similar first sexual experiences in terms of age of initiation and age difference from partner are considered to be abused. Practitioners who work with children and adolescents need to recognize the possibility of sexual activity among pre-adolescent males and to be aware of its implications.

Adolescent↗
PubMed1992

Modifying the mouse: design and desire.

Genetic modification of endogenous genes in mice has become possible by applying gene targeting techniques to embryonic stem (ES) cells and using specific clones of cells to generate mice. Despite the experimental opportunities offered by the creation of organisms with specific genetic changes, there are considerable technical obstacles which can confound the routine implementation of this technology. This review addresses some recent advances in the ability to construct mice with a variety of genetic modifications. These include an increased understanding of the basic cell biology and in vitro growth characteristics of ES cells, which has facilitated germ line transmission of manipulated clones on a routine basis. The techniques that are used to isolate "targeted" clones of ES cells have been summarized, and the current status of strategies which have been successfully used to make very specific modifications of the genome are discussed.

Alleles↗
PubMed1992

A national model of faculty development in addiction medicine.

Increasing the number of faculty with expertise in addiction medicine is one of the challenges facing the medical community in the 1990s. To meet this challenge, the Society of Teachers of Family Medicine created a faculty development course to increase the expertise of family practice faculty involved in teaching residents. The authors describe the development, implementation, and consequences of the five-day intensive course that was taught to 165 participants at ten sites in 1990. The participants' self-reporting before and three months after the course showed significant increases in the numbers of participants who taught addiction medicine in eight of 11 clinical situations. The authors conclude that the course represents a model of faculty development in addiction medicine that is applicable to other specialties and health professions.

Evaluation Studies as Topic↗
PubMed1992

Coexpression of the simian immunodeficiency virus Env and Rev proteins by a recombinant human adenovirus host range mutant.

Recombinant human adenoviruses (Ads) that replicate in the intestinal tract offer a novel, yet practical, means of immunoprophylaxis against a wide variety of viral and bacterial pathogens. For some infectious agents such as human immunodeficiency virus (HIV), the potential for residual infectious material in vaccine preparations must be eliminated. Therefore, recombinant human Ads that express noninfectious HIV or other microbial proteins are attractive vaccine candidates. To test such an approach for HIV, we chose an experimental model of AIDS based on simian immunodeficiency virus (SIV) infection of macaques. Our data demonstrate that the SIV Env gene products are expressed in cultured cells after infection with a recombinant Ad containing both SIV env and rev genes. An E3 deletion vector derived from a mutant of human Ad serotype 5 that efficiently replicates in both human and monkey cells was used to bypass the usual host range restriction of Ad infection. In addition, we show that the SIV rev gene is properly spliced from a single SIV subgenomic DNA fragment and that the Rev protein is expressed in recombinant Ad-SIV-infected human as well as monkey cells. The expression of SIV gene products in suitable live Ad vectors provides an excellent system for studying the regulation of SIV gene expression in cultured cells and evaluating the immunogenicity and protective efficacy of SIV proteins in macaques.

Adenoviridae↗
PubMed1992

Faecal unconjugated bile acids in patients with colorectal cancer or polyps.

The unconjugated faecal bile acid profiles of 14 patients with colorectal cancer, nine patients with polyps and 10 controls were compared using gas liquid chromatography, controlling for such confounding variables as cholecystectomy, gall stones and hepatic function. Patients with adenomatous polyps had a higher concentration of faecal bile acids (5.23 mumol/g, 2.16-13.67 (median, range) v 1.96, 0.91-6.97; p = 0.016) lithocholic acid (2.41, 0.88-3.22 v 1.07, 0.38-2.03; p = 0.013) and total secondary bile acids (5.23, 2.16-13.4 v 1.96, 0.73-6.63; p = 0.02) compared with control subjects. Patients with colorectal cancer had an increased (p = 0.029) proportion of secondary faecal bile acids (mol%) compared with controls (100, 96.5-100 v 95.19, 81.73-100) and the ratios of the primary bile acids, cholic and chenodeoxycholic acid, to their respective derivatives (secondary bile acids) were significantly lower in cancer patients compared with control and patients with polyps (p = 0.034 to 0.004). This study lends further support to the theory that bile acids may play a role in the development of polyps and colorectal cancer.

Adenocarcinoma↗
PubMed1992

Improving resources for foster care.

The number of foster children and their psychological and medical morbidity are growing. To gain insight into how to recruit and retain foster homes, characteristics of 64 foster families were determined by interview. Foster parents had low-to-moderate incomes, were approaching middle age, had underutilized home space, and wanted more children. Most enjoyed foster care and planned to continue. Twenty-three percent of the 64 had half of all foster children in the study in their homes at interview and had cared for seven times as many children in the past, including 66% of all the teens and 83% of all the handicapped children who had been in the 64 homes. These "high providers" functioned like group homes for mentally handicapped individuals. Adapting the group-home concept to foster homes could improve care, especially for children with special needs.

Adult↗
PubMed1992

Fresh osteochondral allografts for post-traumatic defects in the knee. A survivorship analysis.

Fresh osteochondral allografts were used to repair post-traumatic osteoarticular defects in 92 knees. At the time of grafting, varus or valgus deformities were corrected by upper tibial or supracondylar femoral osteotomies. A survivorship analysis was performed in which failure was defined as the need for a revision operation or the persistence of the pre-operative symptoms. There was a 75% success rate at five years, 64% at ten years and 63% at 14 years. The failure rate was higher for bipolar grafts than for unipolar and the results in patients over the age of 60 years were poor. The outcome did not depend on the sex of the patient and the results of allografts in the medial and lateral compartments of the knee were similar. Careful patient selection, correction of joint malalignment by osteotomy, and rigid fixation of the graft are all mandatory requirements for success. We recommend this method for the treatment of post-traumatic osteochondral defects in the knees of relatively young and active patients.

Adolescent↗
PubMed1992

Clinical pure-tone versus three-interval forced-choice thresholds: effects of hearing level and age.

Hearing threshold levels were measured at 2 kHz using both a standard clinical procedure and a three-interval forced-choice procedure. The 240 subjects (aged 50-75 years) embraced both normal hearing and symmetrical sensorineural hearing impairment. The sample was carefully constructed to dissociate hearing threshold level from age, by oversampling the young impaired and the older normally hearing. The forced-choice threshold was found to be generally acuter than the clinical threshold. This was related to increasing severity of hearing loss at 1.7 dB per 10 dB HL and to age at 1.6 dB HL per 10 years. Hearing threshold accounted for 12% of the variance in the discrepancy between the two types of threshold, while age accounted for only 4% due to the narrow range used. After control for these thresholds and age, there were also significant associations with a self-estimate of hearing ability and with the neuroticism score from a personality questionnaire. When interpreting epidemiological findings, particularly in longitudinal studies, the separation between sensory and cognitive factors in threshold measures needs to be considered. The obtained discrepancies as a function of hearing level and age were applied to a statistical model for population prevalences for hearing impairment. The results suggested that the choice of method could have material effects on overall prevalence estimates and on the magnitude of the apparent age effect.

Age Factors↗
PubMed1992

Hearing impairments in middle age: the acceptability, benefit and cost of detection (ABCD).

The major epidemiological investigations of hearing impairment, disability and handicap show that the elderly are the group most disabled by their hearing impairment. There is considerable debate concerning the most efficient way of reducing this inevitable burden of age-related hearing impairments in the next generation. Early fitting of 'targeted' individuals with hearing aids may help but there are a large number of methodological problems associated with conducting and evaluating such a programme of research (especially retrospectively). The logical prerequisite to early fitting as a means of reducing later disability is to ascertain the acceptability of and benefit given by intervention at this early stage. This study therefore set out to investigate the age/sex register provided by the primary physician (GP) as an appropriate base to identify candidates for early aid fitting among a sample of middle-aged patients (50-65 years) living in Roath, Cardiff. Of the 662 who replied to an initial contact letter (1050 were on the age/sex register), 21 already possessed hearing aids. After screening and examination 66 people were offered some form of management which was accepted by 43 during the course of the study. Aid use thereby increased from about 3% to over 9% in this middle-aged group. A 2 year follow-up indicated continued use of the aids, and benefit on a speech reception task was measured. The cost of detecting those who might benefit was calculated using a two-question 'paper and pencil' screen as the first step. A national programme for Wales would cost at least 188,000 pounds per annum at 1990 prices over an initial 5 year span if a criterion which aimed to find at least 45 dB HTL impairments over mid-frequencies was implemented. For a criterion of 35 dB the cost would be 378,000 pounds pa.

Auditory Threshold↗
PubMed1992

The epidemiology of childhood hearing impairment: factor relevant to planning of services.

In the Nottingham District Health Authority we found that one in 943 babies born between 1983-1986 have a sensorineural or mixed hearing impairment (at 50 dB HL or greater in the better ear averaged over the frequencies 0.5, 1, 2, 4 kHz) that is either congenital or progressive in nature. If this figure is broken down between non-neonatal intensive care unit babies and neonatal intensive care unit (NICU) graduates, we find that one in 174 NICU graduates have a hearing impairment compared with one in 1278 non-NICU babies. Excluding from the non-NICU baby population those with a known family history of hearing impairment, and those with a known relevant syndrome at birth, there is a 10.2 to 1 odds ratio for babies in NICU to have such hearing impairments compared to this restricted 'normal' baby population. In addition NICU babies with a hearing impairment were considerably more likely to have another disability (odds ratio 8.7 to 1). Acquired sensorineural or mixed impairments comprised about 9% of the children with impairments by 3 years of age. Twenty per cent of the patients seen at the Children's Hearing Assessment Centre (CHAC) with better-ear impairment of 95 dB HL or greater had acquired hearing impairments. The mean age of referral for congenital hearing impairments was found to be a function of severity and NICU status. For children with better-ear hearing impairments of 80 dB HL or greater, the mean and median ages of referral were both 8 months (s.d. 4 months).

Audiometry, Pure-Tone↗