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Biomedical subjects

C Hogg

Publications and source records attributed to C Hogg.

At least 19 recordsLinked to original sources
PubMed2001

Whose interests do lay people represent? Towards an understanding of the role of lay people as members of committees.

Increasingly, lay people are appointed as members to health service committees. The term 'lay' is used loosely and the reasons for involving lay people are seldom clearly defined. This paper argues that the different roles that lay people play need to be explicitly defined in order for their contributions to be realized. Although lay members of health service committees are generally assumed to be working for patients' interests, our observations lead us to think that some lay people tend to support professionals' or managers' interests rather than patients' interests as patients would define them. We suggest that lay people fall into three broad categories: supporters of dominant (professional) interests, supporters of challenging (managerial) interests and supporters of repressed (patient) interests. These alignments should be taken into account in appointments to health service bodies. Further research is needed on the alignments and roles of lay members.

Allied Health Personnel↗
PubMed1999

[Color vision in relation to age: a study of normal values].

BACKGROUND: It is difficult to quantify thresholds in most colour vision tests, and this is especially the case for tritan hues, where a strong age-related increase of threshold has been reported. With the development of computer-graphic methods it is possible to remove brightness clues caused by lens absorption. This study attempts to give normative values for colour contrast thresholds and assess the age related changes therein. PATIENTS AND METHODS: 115 patients aged between 6 & 71 years were tested for central and peripheral colour contrast sensitivity. No patient had any systemic or eye disease. As a preliminary, heterochromatic flicker balance between the luminosities of the R and G and B and G phosphors was established, so that all colours subsequently generated were isoluminant for the person tested. Then, using a modified binary search technique, colour contrast thresholds were established using both 2 degree optotypes, for central vision, and a ring, 12.5 degrees in radius for peripheral vision. In the latter case, the observer had to name the position of the missing quadrant in the ring. Stimuli were presented for 200 msec at 1 Hz. Colours were modulated on protan, deutan or tritan colour axis. RESULTS: No correlation between age and central colour vision thresholds was observed. By contrast a significant but only minor increase of peripheral colour vision threshold was observed for the peripheral protan and tritan axis. DISCUSSION: The present system removes luminance clues from colour vision tests and permits both central and peripheral retina to be tested. The results are simple in that the influence of age can be neglected. The variability of threshold results is small, and it is easy to detect the relatively large changes associated with disease. Since high-quality monitors are standardised and calibrated, providing the stimulus parameters described are adhered to, the results given here for upper limits of normal may be used for other similar systems.

Adolescent↗
PubMed1998

Decision making: the context of nurse prescribing.

From October 1994 qualified district nurses and health visitors from eight demonstration sites in England have been able to prescribe from a limited list of formulary items. Data collected from nurses formed only one part of the evaluation of nurse prescribing. These data highlighted a number of areas where prescribing nurses were faced with difficult decisions. A number of authors have considered how both doctors and nurses make decisions, and the factors which may influence the decision making process. With reference to the literature this paper focuses on the findings related to decision making in the context of nurse prescribing.

Community Health Nursing↗
PubMed1998

Nurse-patient relationships: the context of nurse prescribing.

Nurse prescribing was initiated in the United Kingdom in October 1994 in eight demonstration sites. The evaluation of this extension to the community nurses' role explored both economic and qualitative benefits to patients, carers, nurses and other health care professionals. In this paper the impact of nurse prescribing on patients is explored. Benefits experienced by patients are described along with the difficulties encountered. The patients' views regarding nurses as prescribers are also explored. Data were collected by means of interviews with patients/carers, the focus of which was to evaluate changes associated with nurse prescribing. Patients raised a number of issues associated with their relationship with nurses. Patients valued nurses for both their accessibility and approachability, which led them to discuss health issues which would not otherwise have been brought to the attention of the general practitioner. The arguments which support the incorporation of these qualities into an expanded nursing role are presented.

Attitude to Health↗
PubMed1998

Expression of monocyte chemoattractant protein-1 in the bovine corpus luteum around the time of natural luteolysis.

Monocyte chemoattractant protein (MCP-1) is a specific chemoattractant for monocytes/macrophages that could have a role in the influx of macrophages into the corpus luteum (CL) during structural luteolysis. In this study, reverse transcription-polymerase chain reaction and in situ hybridization were used to investigate MCP-1 mRNA expression in CL collected from 18 heifers between Days 15 and 20 of the estrous cycle. There was expression of mRNA encoding MCP-1 in luteal tissue from all cows; however, expression was greater in animals that had undergone luteolysis at the time of CL collection as compared to animals in which the CL was still functional. Similarly, in situ hybridization showed greater expression of mRNA encoding MCP-1 in CL after functional luteolysis. There was also evidence of increased MCP-1 mRNA expression in an animal with a functional CL where the systemic concentration of prostaglandin F2alpha metabolite was high at the time of tissue collection. T lymphocyte populations, identified by immunohistochemistry, had a distribution similar to that of cells expressing MCP-1 mRNA within the CL, but other cell types were also involved. These results demonstrate an increase in MCP-1 mRNA after functional luteolysis in the cow, which may be related to the influx of macrophages that occurs at this time.

Animals↗
PubMed1996

The heritability of bone mineral density, ultrasound of the calcaneus and hip axis length: a study of postmenopausal twins.

Population based studies have demonstrated that having a first degree relative with a hip fracture is predictive of future hip fractures. Postmenopausal bone mineral density (BMD), ultrasound of calcaneus and hip axis length are associated with hip fracture, with the association for ultrasound and hip axis length being independent of BMD. The aim of this study was to determine the genetic component of these three important risk factors. We performed a classical twin study using 500 normal female twins, 128 identical and 122 non-identical pairs, aged 50 to 70 years. We measured bone mineral density at multiple sites, hip axis length (distance from the inner rim of the acetabulum to the greater trochanter), broadband ultrasound attenuation and velocity of sound of the calcaneus. Bone density had a strong genetic component at all sites with estimates of heritability ranging from 0.46 to 0.84. Hip axis length and velocity of sound had major genetic components with estimates of 0.62 and 0.61 respectively, which remained virtually unchanged after adjustment for bone mineral density. Broadband ultrasound attenuation had a moderate genetic component with an estimate of 0.53, which was reduced further to 0.45 after adjustment for BMD. In summary, all three bone measurements, which are independently associated with hip fracture, are independently heritable. This study suggests that a combination of different genetic factors acting on the structure, dimensions and density of bone may explain the importance of family history as a risk factor for hip fracture.

Aged↗
PubMed1993

Congenital nystagmus cosegregating with a balanced 7;15 translocation.

We report a family in which autosomal dominant congenital nystagmus cosegregates with a balanced 7;15 translocation. Ophthalmic investigation showed predominantly horizontal nystagmus with a small rotatory component and no significant loss of visual function. This finding suggests a possible localisation for autosomal dominant congenital nystagmus (McKusick 164100).

Chromosomes, Human, Pair 15↗
PubMed1993

Evidence from human electroretinogram A and off responses that color processing occurs in the cones.

PURPOSE: To investigate two apparent anomalies of the human electroretinogram: the "on" and "off" components of the cone based PIII are unequally sized, and transitions from red to green, which are electroretinographically silent, yield reverse transitions (green to red) in which a-waves develop. METHODS: Ganzfeld electroretinograms were obtained with intense 100 msec flickering flashes from red and green light-emitting diode. Such stimuli light-adapt the retina, and the responses are caused by the excitation of long and medium wavelength cones. RESULTS: In the 10-20 msec after the beginning of a flash (black to green or black to red) the beginning of rapid receptor-generated a-wave is seen. Ten to twenty milliseconds after the end of the flash, the beginning of a rapid positive-going off response, also derived from receptors can be seen. If the retina is stimulated by the abrupt change from one wavelength of light to another (eg, from "green" to "red"), at times > 20 msec after the change there are always slow changes in potential (presumably caused by postsynaptic activity) regardless of the relative intensities of red and green. However, if the two light intensities are adjusted appropriately, 10-20 msec after the transition from green to red no electroretinographic a-wave (or off response) develops--the transition is "silent." When the transition reverses (changes back from red to green), an a-wave occurs. In the same way if a red-to-green transition is made silent by altering the relative light intensities, the green-to-red reversal evokes an a-wave. This occurs for numerous pairs of red and green intensities. Rod intrusion or minor electroretinogram components do not explain this result. The relative red:green intensity in two color-anomalous subjects is different to that in three normal subjects. The rule for a silent transition is that the decrease in excitation in one cone type should be twice the increase in excitation in the second cone type. CONCLUSIONS: The most likely cause is a reduction in the amplitude of cone receptor potentials 20-50 msec after the onset of the stimulus, caused by a sign-reversing feedback mechanism such as that described in amphibians. This implies that the chromatic signals for color vision required by theorists are partly generated in the cones.

Color Perception↗
PubMed1992

The pattern electroretinogram in glaucoma and ocular hypertension.

Thirty one eyes with established glaucoma, 61 high risk ocular hypertensive (OHTs) eyes, 66 medium risk OHT eyes, 58 low risk OHT eyes, and 47 control eyes have been followed for up to 2 years by clinical examination and pattern electroretinography (PERG). The study was 'masked' so electrophysiological and clinical data were kept separate. Criteria have been devised which enable PERG measurements to distinguish all established glaucomatous eyes from all normal controls; these criteria demonstrate abnormalities in some OHT eyes, particularly those at high risk. The PERG abnormality is greatest in eyes with established glaucoma in which the intraocular pressure has been lowered by treatment. The PERG becomes smaller as the degree of clinical abnormality increases. Test-retest variability of the PERG is sufficiently low to ensure that most of those first described as abnormal continue to be so.

Adult↗
PubMed1991

Macular colour contrast sensitivity in ocular hypertension and glaucoma: evidence for two types of defect.

Colour contrast sensitivity (CCS) of a large cohort of glaucomatous patients, ocular hypertensive patients (OH), and normal persons was measured at six-month intervals during a two-year period. The OHs were graded into high, medium, and low risk groups. 69% of glaucomatous patients and 32% of all OHs had CCS thresholds greater than the mean plus 2 SDs of the controls. Satisfactory specificity and sensitivity could not be obtained by adjusting the criterion of threshold. In abnormal eyes, progressive small increases of threshold occurred during the study, but glaucomatous eyes with normal thresholds on the first visit retained normal thresholds in the subsequent visits. Although our system is very sensitive and precise, the proportion of abnormalities detected is no greater than with other techniques. In some glaucomatous patients there is a true preservation of colour vision which does not merely reflect the limitations of the test employed.

Color Perception↗
PubMed1990

Community health councils. Their role after the NHS White Paper.

Christine Hogg and Fedelma Winkler review the major and varied changes being introduced in the management of community health councils by different regional health authorities in the wake of the NHS Bill. This piecemeal approach may lead to more variations in the standards of service that individual CHCs offer the public and they argue that there needs to be a coherent policy about the role of CHCs and evaluation and monitoring of their functions.

Community Participation↗
PubMed1988

Botulinum toxin therapy for squint.

Four hundred and five patients have been treated with injections of Botulinum neurotoxin A to extraocular muscles in the Botulinum Toxin Clinic at Moorfields Eye Hospital from November 1982 until the present. The indications and outcome of therapy are described and discussed.

Adolescent↗