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Biomedical subjects

D Clark

Publications and source records attributed to D Clark.

At least 73 records · Page 4Linked to original sources
PubMed1999

Environmental health officers' understanding about an aboriginal environmental health worker program in the Northern Territory.

OBJECTIVE: To explore environmental health officers' (EHOs) perception that a program to train Aboriginal people as environmental health workers in 10 remote Northern Territory communities was not operating well. METHOD: Phenomenography, an approach within the qualitative domain, was used to explore 15 EHOs' understanding about the program during 1996-97. Respondents came from four of the Territory's five operational districts. RESULTS: Respondents were unclear about worker roles and responsibilities within the program. Perceptions about their own skills as trainers in a cross-cultural context inhibited their abilities to support the program effectively. CONCLUSIONS: Addressing the support, orientation and professional development needs of EHOs will enhance program effectiveness. IMPLICATIONS: Support staff should be adequately prepared and trained before a new program is commenced.

Allied Health Personnel↗
PubMed1999

Molecular mapping of chromosome 2 deletions in murine radiation-induced AML localizes a putative tumor suppressor gene to a 1.0 cM region homologous to human chromosome segment 11p11-12.

Radiation-induced acute myeloid leukemias (AMLs) in the mouse are characterized by chromosome 2 deletions. Previous studies showed that a minimal deleted region (mdr) of approximately 6.5 cM is lost from one homologue in chromosome 2-deleted AMLs. An AML tumor suppressor gene is proposed to map within this mdr. In this study, we refine the mdr to a I cM interval between markers D2Mit126 and D2Mit185 by microsatellite analysis of 21 primary radiation-induced F I AMLs. The construction of a partial yeast artificial chromosome (YAC) contig spanning the mdr and the location of six known genes indicated that the 1 cM mdr is homologous to human 11p11-12, a region implicated in some human AMLs. Screening of five cell lines derived from primary radiation-induced AMLs for homozygous loss of microsatellites and genes mapping within the mdr revealed loss of both copies of the hemopoietic tissue-specific transcription factor Sfpi1(PU.1/Spi1) in one cell line. Studies of primary and F1 AMLs failed to implicate Sfpi1 as the AML tumor suppressor gene. YAC contig construction, together with data suggesting that the critical gene flanks Sfpi1, represents significant progress toward identifying an AML tumor suppressor gene.

Animals↗
PubMed1998

Perturbation of nucleosome structure by the erythroid transcription factor GATA-1.

The ability of transcription factors to gain access to their sites in chromatin requires the disruption or displacement of nucleosomes covering the promoter, signalled by the generation of a nuclease hypersensitive site. We characterise here the alterations in nucleosome structure caused by binding of the erythroid factor GATA-1 to a nucleosome carrying GATA-1 sites. DNase I and micrococcal nuclease probes show that GATA-1 binding causes extensive, cooperative breakage of the histone/DNA contacts to generate a complex very similar to that formed by the factor with free DNA. The only region which differs is confined to about 50 bp surrounding the nucleosome dyad axis which appears to be the domain of residual contact between the DNA and histone octamer. Despite considerable breakage of the histone/DNA contacts, the complex is completely stable in solution, and disruption of the nucleosome is entirely reversible: it is regenerated quantitatively upon removal of the transcription factor. Moreover, the histone 2A/2B component of the octamer does not exchange to external competitor. We suggest that formation of this complex may be a step in the generation of a fully hypersensitive site in vivo over regulatory elements containing GATA family binding sites.

Animals↗
PubMed1998

Do non-dopaminergic neurons in the ventral tegmental area play a role in the responses elicited in A10 dopaminergic neurons by electrical stimulation of the prefrontal cortex?

It is rapidly becoming apparent that the prefrontal cortex (PFC) plays a major role in controlling the activity of midbrain dopaminergic (DA) neurons. We have previously demonstrated that electrical stimulation of the PFC elicits inhibition-excitation (IE) and excitation (E) activity patterns in DA neurons in the ventral tegmental area (VTA; A10 cell group). Since non-DA neurons in the VTA are cortically innervated, synapse upon DA neurons and appear to have an inhibitory impact, we determined the extent to which the responses of these neurons to stimulation of the PFC could account for the responses seen in DA neurons upon cortical stimulation. Stimulation of the PFC (0.25 mA and 1.0 mA) elicited three categories of response in the majority of VTA non-DA neurons. Types I and II were characterised by a short-to-moderate latency excitation (referred to as "early excitations"), in the latter case preceded by inhibition. Type III responses consisted of inhibition in the absence of an early excitation. Elements of these responses were compared with the temporal characteristics of key elements of responses elicited in DA neurons by PFC stimulation. Although the early excitations in non-DA neurons preceded the inhibitions in DA neurons exhibiting IE responses, the early excitations began approximately 100 ms before the inhibitions in DA neurons and often ended several tens of milliseconds before the inhibitions began, making a causal relationship between these events unlikely. The inhibitions in Type III responses, combined with the inhibitions which followed the early excitations in many Type I and II responses, showed temporal characteristics that suggested a possible causal relationship with the excitations in DA neurons exhibiting E responses, but not those exhibiting IE responses. However, since the excitatory phases of E and IE responses appear to be homologous, the lack of involvement of non-DA neurons in the excitatory phase of IE responses tends to cast doubt on the involvement of non-DA neurons in the excitation during E responses. In fact, the most coherent impression that emerges is that non-DA neurons in the VTA do not influence the activity of A10 DA neurons on a short time-scale (i.e. phasically), but instead may influence activity on a longer time-scale (i.e. tonically).

Action Potentials↗
PubMed1998

Inter and intra-species-related differences in the regulation of the cardiac autonomic system.

The heart rate response to isoproterenol (HR-Iso), density and affinity (kd) of beta-adrenergic (beta-AR) and muscarinic (M2) receptors were compared among three rodents with different generation-life histories of confinement and of high altitude exposure. The European guinea pig (Cavia porcellus) (EGp), a laboratory animal that arrived in Europe after the Spanish Conquest of South America and the Peruvian guinea pig (C. porcellus) (PGp), a semi-wild animal that came from the altiplano to sea level at least 25 generations ago, were used for intra-species comparison. Wistar rats (WR) were used for inter-species comparison as representative of a typical sea level laboratory animal. The HR-Iso was lower in EGp than in the PGp. The PGp showed the highest beta-AR density (P < 0.0005) and the highest beta-AR kd values (P < 0.0005) when compared to both EGp and WR groups (beta-AR Bmax (fmol mg-1 prot), WR, 19 +/- 4; Egp, 34 +/- 10; PGp, 74 +/- 15. beta-AR kd (pM), WR, 24 +/- 10; Egp, 17 +/- 7; PGp, 39 +/- 14). In contrast, PGp showed lower M2 receptor density values than the EGp (P < 0.0005). The WR had the highest M2 receptor densities (M2 Bmax (fmol mg-1 prot), WR, 188 +/- 15; Egp, 147 +/- 9; PGp, 118 +/- 6 and M2 kd (pM), WR, 65 +/- 12; Egp, 67 +/- 6; PGp, 92 +/- 2). The inter and intra-species differences found may be related to their respective history of confinement rather than to their history of exposure to high altitude.

Altitude↗
PubMed1998

Are computerized interviews equivalent to human interviewers? CIDI-Auto versus CIDI in anxiety and depressive disorders.

BACKGROUND: The equivalency of the Composite International Diagnostic Interview delivered by human interviewers (CIDI) and its computerized version (CIDI-Auto) was examined for anxiety and depressive disorders. METHODS: Subjects were 40 patients at an Anxiety Disorders Clinic and 40 general medical practice attenders. The CIDI-Auto and CIDI were administered in counterbalanced order on the same day and measures of computer attitudes and the acceptability of the two interview formats were also taken. RESULTS: The CIDI-Auto and the CIDI were found to be equally acceptable to subjects on the dimensions of comfort and preference, while the CIDI-Auto was rated as less embarrassing but too long in comparison with the CIDI. The agreement between the two formats was acceptable with kappa values for ICD-10 diagnoses being above 0.65 and for DSM-III-R diagnoses above 0.5 except for two diagnoses (generalized anxiety disorder and dysthymia). Discrepancies between the two formats were predicted by computer attitudes and not by computer experiences or the tendency to respond in a socially desirable fashion. CONCLUSIONS: It is concluded that the CIDI-Auto in its self-administered form is an acceptable substitute for the CIDI for suitable subjects.

Adult↗
PubMed1998

Palliative care in chronic obstructive airways disease: a needs assessment.

The view that palliative care should move beyond cancer is widely endorsed, however, there remains a lack of clarity about the level at which this should occur. In order to target the palliative approach effectively, the value of more detailed and localized needs assessment becomes apparent. This paper provides evidence from a study commissioned by a department of public health, where the focus was the palliative care needs of an individual with chronic obstructive airways disease (COAD). Over a six-month period, 63 individuals in the district were interviewed about their experiences of living with COAD and the services utilized, using a combination of qualitative and quantitative research methods. The findings revealed a poor quality of life, relating to a high degree of social isolation and emotional distress, associated with low physical functioning and disability, and physical symptoms. Current service provision focused on acute exacerbations. Consequently, there is a need to manage the health and social care interface more effectively, with a shift in emphasis from reactive ad hoc provision, which is where the palliative approach to care could be best suited to meet the needs identified.

Aged↗
PubMed1998

Intrabony neurilemmoma: diagnosis and management.

The authors present a case of a mandibular neurilemmoma discovered on routine radiographic examination of an asymptomatic young woman. The lesion was surgically removed and there was no radiographic evidence of recurrence. A review of the literature is presented and the differential diagnosis, prognosis and treatment of this benign neurogenic tumor are discussed.

Adult↗
PubMed1998

Unmet health care needs. Comparison of rural and urban senior center attendees.

Rural-dwelling older adults are in poorer health and have less access to health care resources than urban older adults. However, little is known about specific unmet needs which exist for urban and rural populations. This study compared self-reported health status, use of services, and unmet health care needs of 106 elderly individuals residing in rural and urban settings to determine if these variables differed based on geographic location. Data were gathered on the three dependent measures using the Elderly Health Care Needs Assessment Questionnaire. Findings revealed rural older adults were not in poorer self-reported health (chi 2 = 1.85, p = .60). However, a t test showed rural subjects were significantly poorer in objective health as measured by the number of reported symptoms (t = 224, p = .02). Despite having a greater number of specific health complaints, these rural elderly individuals did not use significantly more services (t = 1.16, p = .24) or report more unmet needs (chi 2 = 3.67, p = .055), thereby reinforcing traditional views of rural older adults being in poorer health but also more self-reliant in matters related to health care. The results of this study provide information which will improve nursing practice in rural and urban settings and provide direction for further research.

Aged↗
PubMed1998

Assessment of a new through-the-eyelid technique for 'A' scan ultrasound ocular axial length measurement.

This study evaluated the repeatability both within one session and between two sessions of a new technique of axial length measurement using 'A' scan ultrasound through the eyelids. The validity of the technique was assessed by comparing the results to those taken through the cornea. The new technique was very reliable, the mean difference between two readings at the first visit being 0.01 mm and between the two visits being 0.01 mm with 95% of differences between two readings in both cases being less than two standard deviations. The axial length measurements through the lid were a mean of 0.05 mm longer than the corneal measurements. The standard deviation of the difference between the two forms of measurement was 0.16 mm and 95% of axial length readings through the eyelid were within two standard deviations (+/- = 0.32 mm) of the corneal measurement. Providing strict criteria are applied to the quality of the 'A' scan images we believe that satisfactory axial length values may be obtained using this technique.

Anisotropy↗