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Biomedical subjects

C Owen

Publications and source records attributed to C Owen.

At least 55 records · Page 3Linked to original sources
PubMed1996

The misting characteristics of spectacle lenses.

When a spectacle wearer enters a warm environment after having been in a cooler one, his/her spectacles may 'mist up' due to the formation of condensation on the lens surface. Both the physical properties of the spectacle lens and a number of environmental factors determine how long spectacles take to demist. The relative misting performance of crown glass, CR39 and polycarbonate spectacle lenses were assessed using a novel technique. A box in which the environmental conditions could be controlled was used first to cool the lens and then to warm it. This change in temperature caused condensation to form on the lens surface. By projecting the image of a grating through the lens onto a linear array of photodiodes it was possible to measure the contrast transmission of the spectacle lens as it demisted. Each lens type misted and demisted in a characteristic way. The polycarbonate lens demisted more rapidly than the CR39 lens which, in turn, demisted more rapidly than the glass lens. This indicates that polycarbonate spectacle lenses should be used in conditions where the adverse effects of spectacle misting need to be minimised.

Eyeglasses↗
PubMed1995

Structure of bacterial flagellar filaments at 11 A resolution: packing of the alpha-helices.

Recent advances in the analysis of electron micrographs of frozen, hydrated bacterial filaments have allowed us to average data from more than 150 images and to reconstruct the bacterial flagellar filament of Salmonella typhimurium at a resolution of approximately 11 A. In addition to the outermost features seen in earlier lower resolution maps of the filament, we find a pair of concentric tubes which surround a approximately A diameter channel at the center of the structure. The walls of these tubes are composed of rod-like features which we have interpreted as columns of individual alpha-helices stacked end-to-end. Each column runs approximately parallel to the helix axis. The wall of the innermost tube, at a radius of approximately 20 A, is formed from 11 such columns. The wall of the second tube is formed from 22 columns which occur alternately at radii of approximately 43 and approximately 47 A. The two concentric tubes are held apart by spacers. These are short, rod-like features, which run approximately parallel to the helix axis. We have interpreted these as additional alpha-helices. By symmetry, each flagellin monomer contributes an alpha-helix to the inner tube, two alpha-helices to the outer tube and a fourth alpha-helix to the spacer. We have tentatively assigned one type of alpha-helix in the outer tube to the approximately 30 C-terminal residues of flagellin while the remaining three alpha-helices are assigned to the approximately 70 N-terminal residues. This interpretation of the reconstruction is consistent with available biochemical, biophysical and amino acid sequence information. We also present details of improved methodology to extract and evaluate the original data and also to assess the statistical significance of features in the three-dimensional map.

Bacterial Proteins↗
PubMed1995

The nature of ophthalmic services, and the education and qualifications of nurses: a national survey.

This paper reports on a national survey undertaken by the Royal College of Nursing (RCN) Ophthalmic Nursing Forum to assess, first, the nature of ophthalmic services and, second, skill-mix and educational opportunities of nurses working with ophthalmic patients. A questionnaire was formulated and tested by members of the committee, with research and statistical support from the School of Nursing Studies, University of Manchester. The questionnaire was sent to the total population of ophthalmic units/hospitals in the UK (n = 168). Following descriptive statistical data analysis it was concluded that in smaller units, that is those with less than 18 beds (NB mean number of beds = 18), less than one in four nurses holds an ophthalmic qualification. Some respondents identified that in 10 instances no nurses held an ophthalmic qualification and that on 12 further occasions only one nurse held a relevant ophthalmic qualification. There are insufficient numbers of nurses holding ophthalmic qualifications. The implications of this situation are discussed and recommendations made.

Career Mobility↗
PubMed1994

Resuscitation in cancer. Comparison of patient and health staff preferences.

One hundred oncology patients from a major teaching hospital and their treating health staff were studied in the second phase of research examining attitudes towards cardiopulmonary resuscitation (CPR). A descriptive approach was used incorporating semistructured interviews of patients and established questionnaire measures, examining knowledge of and attitude towards disease and treatment, psychological functioning, and current and projected attitude toward resuscitation. Health staff also participated in a semistructured interview. This phase of the project focused particularly on a direct comparison of patient and staff assessments. In current circumstances, 10% of patients refused resuscitation. This was associated with disease of good prognosis. In a future hypothetical deteriorated scenario presented to patients, 39% declined resuscitation. This was associated with a past history of suicidal behavior. In current circumstances, health staff designated 14% of patients "Do-Not-Resuscitate" (DNR)--this was associated with a number of variables considered to predict poor outcome in resuscitation. In the future scenario, staff designated 54% of patients DNR--this was associated again with poor resuscitation outcome variables, but also independently, with a past psychiatric history. Comparison of patient and health staff preferences for resuscitation showed moderate yet significant concordance in current circumstances but not in the future scenario. The findings indicate firstly the feasibility of discussing resuscitation preferences with seriously ill patients and secondly an urgent need to improve patient and staff discussions regarding resuscitation, as staff and patients' attitudes to resuscitation differ.

Adult↗
PubMed1993

Gender inequalities in health: social position, affective disorders and minor physical morbidity.

Research has consistently reported a female excess of minor physical morbidity and affective disorders compared to men. Using data from a national cross sectional survey of British women and men aged 18-59, this paper explores three prominent explanations for these patterns: that the female excess is due to problems associated with menstruation and the menopause; that it is 'caused' by the social positions which women occupy in contemporary western societies; and that the excess of affective disorders is 'caused' by women's social positions but that their higher rate of physical illness is psychosomatic in origin. The analysis presented here suggests that problems with menstruation and the menopause cannot explain gender inequalities in minor illness. Similarly the argument that the female excess of minor physical illness is psychosomatic is not supported, indeed, there is evidence that women's experience of minor physical illness may 'cause' their higher rates of affective disorders. Finally, with a few exceptions, the relationship between minor illness and four dimensions of social positions--marital status, employment status, social class and income--were broadly the same for women and men but in each social position category, women report higher rates of both types of ill health than men. It is concluded that present measures of these social positions do not capture the differing experiences of women and men and that more gender sensitive measures are needed if gender inequalities in minor illness are to be understood.

Female↗
PubMed1993

A 13-A map of the actin-scruin filament from the limulus acrosomal process.

We have determined the structure of the actin-scruin filament to 13-A resolution using a combination of low-dose EM and image analysis. The three-dimensional map reveals four actin-actin contacts: two within each strand and two between strands. The conformation of the actin subunit is different from that in the Holmes et al. (1990) model as refined by Lorenz et al. (1993). In particular, subdomain II is tilted in a similar way to that seen by Orlova and Egelman (1993) in F-Mg2(+)-ADP actin filaments in the absence of Ca2+. Scruin appears to consist of two domains of approximately equal volume. Each scruin subunit cross-links the two strands in the actin filament. Domain I of scruin contacts subdomain I of actin and makes a second contact at the junction of subdomains III and IV. Domain II of scruin contacts actin at subdomains I and II of a neighboring actin subunit. The two scruin domains thus bind differently to actin.

Acrosome↗
PubMed1993

Study of the proliferation in human gastric mucosa after in vivo bromodeoxyuridine labelling.

Studies to measure human gastric crypt or gland cell proliferation may have a number of practical clinical applications in relation to both benign and malignant gastric conditions. Bromodeoxyuridine (BrdUrd) labels human gastric mucosal cells in the S phase. Computer aided data analysis of labelled mucosa allows static proliferative indices to be estimated, including the crypt labelling index (LI), the peak labelling position, the distribution of labelled cells and indirectly the crypt growth fraction. Multiparameter flow cytometric analysis of labelled nuclei allows the S phase duration (Ts) of mucosal cells to be estimated. Specimens of histologically normal gastric body (GB, n = 16) and antral mucosa (GA, n = 10) were obtained from 25 patients with gastric carcinomas who received a bolus dose of 250 mg BrdUrd between 3.0 and 15.7 hours before surgery. Tissue sections were stained by an immunohistochemical method and subjected to detailed counting of up to 50 longitudinal crypts per specimen. The total crypt labelling index was calculated by a grid counting method. A significant difference existed between the proliferative compartments of gastric antral and body mucosa measured by a number of criteria. The median lengths of the crypts were 137 cells (GB) and 188 cells (GA). The median peak labelling positions were cell 26 (GB) and cell 61 (GA) from the crypt orifice. The mean crypt labelling indices were 2.8% (GB) and 4.8% (GA). The mean Ts of GA cells was 7.7 hours and of GB cells was 10.8 hours.

Adult↗
PubMed1992

Resuscitation. Patient and staff attitudes in the context of cancer.

One hundred oncology and hematology cancer patients from a major teaching hospital and their treating doctors were studied regarding their attitudes toward cardiopulmonary resuscitation (CPR). A descriptive approach was used, incorporating semistructured interviews of patients and medical staff and established questionnaire measures, examining knowledge of and attitudes toward disease and treatment, and projected attitude toward CPR and current psychological functioning. One-third of the patient sample anticipated a time when they would not consent to cardiopulmonary resuscitation. This was significantly associated with good disease prognosis. Patients with a psychiatric past history were also overrespresented. It appears that patient attitude to treatment withdrawal and refusal of CPR is related to disease progression and likely to change over time. This supports a dynamic and evolving model of advance directives rather than any fixed decree. Medical staff reported that they planned to provide half the sample with intensive medical treatment (including Intensive Care support in the event of their cardiac arrest), and 32% were designated for ward-based resuscitation only. Eighteen percent would not be resuscitated. These patients were older, had more treatment side effects, and a poorer quality of life. Those patients with either a psychiatric past history or higher ratings of depressive affect were also overincluded in the doctors' "Do-Not-Resuscitate" (DNR) group. These results suggest that there are other qualitative factors (e.g., current psychological functioning and past psychiatric history) that contribute to DNR decisions beyond the usual disease-based criteria seen in formal DNR protocols.

Adult↗
PubMed1992

Activation of a cryptic streptomycin-resistance gene in the Bacteroides erm transposon, Tn4551.

Bacteroides compound transposons encoding erm resistance are highly homologous but previous studies have shown some divergence of Tn4551. Results presented here describe a novel Tn4551 streptomycin-resistance gene, aadS, that was phenotypically silent in wild-type Bacteroides. However, aadS expression could be activated by a trans-acting chromosomal mutation. The aadS-encoded peptide displayed significant homology to Gram-positive streptomycin-dependent adenyltransferases, and enzymatic analysis confirmed the production of this activity. Examination of the nucleotide sequence showed that 200 bp upstream of aadS, the DNA base composition changed abruptly from 31% G+C to 48% G+C. These two regions were demarcated by a DNA sequence with homology to the recombination hot spots reported for Tn21 and the Bacteroides ermFU gene and to sequences at the ends of the chromosomal Bacteroides conjugal element, XBU4422.

Amino Acid Sequence↗
PubMed1992

OH marketing--Part 1: The background.

OH practitioners are being asked to justify their services within organisations. In the first of two articles Christine Owen and Dr Victor Newman discuss ways of developing new approaches to the marketing of occupational health.

Cost-Benefit Analysis↗
PubMed1991

Formal complaints against general practitioners: a study of 1000 cases.

This study was carried out to determine the reasons given by patients in making formal complaints against general practitioners. A sample of 1000 complaints made by UK patients about general practitioner principals over the period 1982-89 was randomly selected from the computer database of the Medical Protection Society and retrospectively analysed. Thirteen categories of criticism were identified. The most common circumstance in which patients complained was when they believed there had been failure to visit. In nearly one third of cases the complaints were associated with the death of a patient. In a quarter of the letters it was clear that the patient's motive for complaining was concern to protect other patients. General practitioners should bear in mind that in declining to visit they could be inviting criticism, particularly if the patient dies.

Clinical Competence↗
PubMed1984

Nifedipine blocks sleep induction by flurazepam in the rat.

Previous studies have implicated the benzodiazepine receptor in the sleep-inducing effects of these widely used hypnotics, but the effector mechanism of this process is poorly understood. There is also in vitro evidence that benzodiazepines enhance calcium entry into synaptosomal preparations, leaving open the possibility that altered calcium flux may be involved in their actions. In order to explore this hypothesis, we administered intraventricular nifedipine, a calcium blocking agent. It was found that pretreatment with a dose of nifedipine which by itself does not affect sleep will prevent sleep induction by flurazepam in rats. Effects on anticonvulsant properties of flurazepam or anxiolytic effects of diazepam were not apparent. This suggests that changes in calcium channel function may be involved in the hypnotic action of benzodiazepines.

Animals↗
PubMed1984

Continuities of common behaviour problems in preschool children.

This paper describes the prevalence of behaviour problems in 2 populations of preschool children in London, and the continuities over time of common problems. Night waking was the most common problem under the age of 2, being reported in 21% of 1-year-olds. Just under half of these night wakers were still waking at 18 months, and from 18 months to 2 years just over half the children continued waking The continuities of feeding problems were stronger after the age of 2 years, with poor appetite being reported to persist more than food fads. Over 2 years the most common problem reported was temper tantrums, and 45% of the children having frequent tantrums at 2 years were still having frequent tantrums at 3 years. The implications for services and the need for intervention studies are discussed.

Child Behavior Disorders↗