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Biomedical subjects

M Clarke

Publications and source records attributed to M Clarke.

At least 181 records · Page 10Linked to original sources
PubMed1993

Inside looking out.

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Hospital-Patient Relations↗
PubMed1993

Evaluating perinatal mortality rates: effects of referral and case mix.

OBJECTIVE: To evaluate perinatal mortality rates as a method of auditing obstetric and neonatal care after account had been taken of transfer between hospitals during pregnancy and case mix. DESIGN: Case-control study of perinatal deaths. SETTING: Leicestershire health district. SUBJECTS: 1179 singleton perinatal deaths and their selected live born controls among 114,362 singleton births to women whose place of residence was Leicestershire during 1978-87. MAIN OUTCOME MEASURE: Crude perinatal mortality rates and rates adjusted for case mix. RESULTS: An estimated 11,701 of the 28,750 women booked for delivery in general practitioner maternity units were transferred to consultant units during their pregnancy. These 11,701 women had a high perinatal mortality rate (16.8/1000 deliveries). Perinatal mortality rates by place of booking showed little difference between general practitioner units (8.8/1000) and consultant units (9.3-11.7/1000). Perinatal mortality rates by place of delivery, however, showed substantial differences between general practitioner units (3.3/1000) and consultant units (9.4-12.6/1000) because of the selective referral of high risk women from general practitioner units to consultant units. Adjustment for risk factors made little difference to the rates except when the subset of deaths due to immaturity was adjusted for birth weight. CONCLUSION: Perinatal mortality rates should be adjusted for case mix and referral patterns to get a meaningful result. Even when this is done it is difficult to compare the effectiveness of hospital units with perinatal mortality rates because of the increasingly small subset of perinatal deaths that are amenable to medical intervention.

Case-Control Studies↗
PubMed1993

Residential care for elderly people: a decade of change.

OBJECTIVE: To determine the changes between 1979 and 1990 in demography and dependency levels in elderly people in residential care. DESIGN: Censuses of those aged 65 years and over in any type of residential care at midnight on 11 December 1979 and 27 November 1990. SETTING: Leicestershire District Health Authority (population 865,133, 1991 census), coterminous with county and social services boundaries. MAIN OUTCOME MEASURES: Age, sex, length of stay, and dependency levels (measured by activities of daily living). RESULTS: In 1990 (1979), 6079 (4678) elderly people were enumerated in 241 (133) establishments, a 30% increase in the numbers of elderly people in residential care and an 82% increase in the number of establishments between 1979 and 1990. Dependency levels rose between 1979 and 1990 in all but the geriatric sector, the greatest increases being found in private residential homes where the largest percentage increase in the number of residents had occurred. CONCLUSIONS: Dependency levels in residential care have risen substantially, particularly in the private sector, even beyond levels expected from the greater numbers of elderly people. With the impending move to community care, dependency levels are likely to rise further, and more appropriate staff training and medical input to homes will become necessary.

Activities of Daily Living↗
PubMed1993

Proton pumps populate the contractile vacuoles of Dictyostelium amoebae.

Amoebae of the eukaryotic microorganism Dictyostelium discoideum were found to contain an interconnected array of tubules and cisternae whose membranes were studded with 15-nm-diameter "pegs." Comparison of the ultrastructure and freeze-fracture behavior of these pegs with similar structures found in other cells and tissues indicated that they were the head domains of vacuolar-type proton pumps. Supporting this identification, the pegs were observed to decorate and clump when broken amoebae were exposed to an antiserum against the B subunit of mammalian vacuolar H(+)-ATPase. The appearance of the peg-rich cisternae in quick-frozen amoebae depended on their osmotic environment: under hyperosmotic conditions, the cisternae were flat with many narrow tubular extensions, while under hypo-osmotic conditions the cisternae ranged from bulbous to spherical. In all cases, however, their contents deep etched like pure water. These properties indicated that the interconnected tubules and cisternae comprise the contractile vacuole system of Dictyostelium. Earlier studies had demonstrated that contractile vacuole membranes in Dictyostelium are extremely rich in calmodulin (Zhu, Q., and M. Clarke, 1992, J. Cell Biol. 118: 347-358). Light microscopic immunofluorescence confirmed that antibodies against the vacuolar proton pump colocalized with anti-calmodulin antibodies on these organelles. Time-lapse video recording of living amoebae imaged by interference-reflection microscopy, or by fluorescence microscopy after staining contractile vacuole membranes with potential-sensitive styryl dyes, revealed the extent and dynamic interrelationship of the cisternal and tubular elements in Dictyostelium's contractile vacuole system. The high density of proton pumps throughout its membranes suggests that the generation of a proton gradient is likely to be an important factor in the mechanism of fluid accumulation by contractile vacuoles.

Animals↗
PubMed1993

Factors associated with decline in function, institutionalization and mortality of elderly people.

Movements between dependency states, institutionalization and death are investigated in a general practice cohort of people aged 75 years and over with follow-up at 5 and 7 years from initial interview. Initially, 1203 people were interviewed, 1124 living in the community and 79 in institutions. By 5 years, 42% (510) had died and by 7 years 58% (700) had died. Dependency was defined as requiring help or aids with at least one activity of daily living (ADL). Of those initially independent, 34% were still independent 7 years later. Women at each age were more likely to become dependent whilst men had higher mortality. Those rating their health as fair or poor were more likely to lose independence at both 5 and 7 years than those rating their health as good. These differences remained, even after adjustment for age, sex and baseline ADL status. With the assumption that once institutionalized a person did not return to live in the community (an assumption upheld by the present data), 7% (79/1124) of those initially resident in the community were institutionalized during the 7 years; the rates for men (6%) being slightly lower than for women (7.5%).

Activities of Daily Living↗
PubMed1993

Adolescent suicide: music preference as an indicator of vulnerability.

OBJECTIVE: This preliminary study investigated possible relationships between adolescents' music preference and aspects of their psychological health and lifestyle. METHOD: Students (mean age 14.76 years) from two randomly chosen high schools completed self-report questionnaires on preferred music types and messages in the music. In addition the Youth Self-Report provided information about suicide ideation, deliberate self-harm, "depression," and "delinquency." Brief risk taking and drug taking scales were administered in addition to questions about family environment. RESULTS: A marked gender bias was shown to exist with 74% of girls preferring pop music compared with 70.7% of boys preferring rock/metal. Significant associations appear to exist between a preference for rock/metal and suicidal thoughts, acts of deliberate self-harm, "depression," "delinquency," drug taking, and family dysfunction. This was all particularly true for girls. In addition, feeling sadder after listening to the preferred music appeared to distinguish the most disturbed group. CONCLUSIONS: The authors recommend that further academic study of these associations is warranted. Both preference for rock/metal music, particularly in girls, and feeling worse after listening to the music may be indicators in adolescents of vulnerability to suicidal thoughts and actions.

Adolescent↗
PubMed1993

Developing a restraint use policy for acute care.

Restraint use has been a recent focus of attention in long-term care facilities. The Joint Commission on Accreditation of Healthcare Organizations, the Commission on Accreditation of Rehabilitation Facilities, and the Food and Drug Administration have devoted attention to the prudent use of restraints. The authors address efforts of an acute care facility to comply with these regulations.

Aged↗
PubMed1993

A case-control study to investigate the role of recent spontaneous abortion in the aetiology of neural tube defects.

Clarke et al. suggested that women who have had a spontaneous abortion are at an increased risk in their next pregnancy of producing an offspring with a neural tube defect (NTD). A matched case-control study was carried out to test the related hypothesis that a spontaneous abortion occurring in the 6-month period prior to the conception of a pregnancy (recent spontaneous abortion) is a risk factor for the development of an NTD in that pregnancy. The cases were 177 singleton pregnancies to non-primigravida Leicestershire women, which were affected by non-syndromal NTDs between 1976 and 1989. Two control pregnancies were matched with each case on intended place of delivery and date of maternal last normal menstrual period (LNMP). After adjusting for potential confounders, recent spontaneous abortion was found to be associated with a decreased relative risk of neural tube defect, odds ratio 0.46, 95% confidence interval 0.20, 1.07. The result provided little evidence in favour of the hypothesis, suggesting instead that prior spontaneous abortion has a protective effect in relation to subsequent NTD development rather than being a major risk factor in the aetiology of NTDs.

Abortion, Spontaneous↗
PubMed1993

Identification of sleep disruption and sleep disordered breathing from the systolic blood pressure profile.

BACKGROUND: Respiratory sleep studies are frequently performed to identify sleep disruption resulting from upper airway obstruction. Traditional polysomnographic studies may not detect brief recurrent sleep disruption and thus fail to recognise a significant problem when apnoea, hypopnoea, or arterial desaturation are not present. Arousal from sleep causes a transient blood pressure rise, and each inspiration causes a transient blood pressure fall. This study assesses whether these blood pressure changes are a useful indirect marker of disturbed sleep, obstructed sleep apnoea, and snoring related sleep disturbance. METHODS: Computer algorithms were developed to identify blood pressure falls caused by inspiration and rises related to arousal from 286 sleeping blood pressure samples of a consistent respiratory state drawn from 51 polysomnographic studies. From these samples, normal ranges for the number of arousal related systolic rises and the average size of the inspiratory falls were established. These were then applied prospectively to all night unedited blood pressure recordings from a further 20 subjects. RESULTS: The size of the inspiratory falls in blood pressure progressively increased from normal sleep, through snoring, to frank obstructive sleep apnoea. The 95th centile of normal was 12.5 mm Hg. The number of arousal related blood pressure rises also increased during obstructive sleep apnoea and periods of snoring with associated arousals, compared with normal undisturbed sleep, and all these periods of disturbed sleep included more than 30 such rises per hour. When these blood pressure features were examined in the 20 subjects studied prospectively, the six with a sleep related breathing disorder could all have been identified from their systolic blood pressure profile alone. CONCLUSIONS: The systolic blood pressure profile may be helpful in identifying patients with obstructive sleep apnoea, snoring with arousals, or other sleep disruption syndromes.

Adult↗
PubMed1993

Calmodulin and the contractile vacuole complex in mitotic cells of Dictyostelium discoideum.

In amoebae of the eukaryotic microorganism Dictyostelium discoideum, calmodulin is greatly enriched on membranes of the contractile vacuole complex, an osmoregulatory organelle. Antibodies specific for Dictyostelium calmodulin were used in the present study to immunolocalize the contractile vacuole complex in relation to the Golgi complex (detected with wheat germ agglutinin) and the microtubule organizing center (MTOC, detected with anti-tubulin antibodies). Cells were examined throughout the cell cycle. Double-staining experiments indicated that the contractile vacuole complex extended to the MTOC in interphase cells, usually, but not always, overlapping the Golgi complex. In metaphase and anaphase cells, the Golgi staining became diffuse, suggesting dispersal of Golgi membranes. In the same mitotic cells, anti-calmodulin antibodies labeled numerous small cortical vacuoles, indicating that the contractile vacuole complex had also become dispersed. When living mitotic cells were examined, the small cortical vacuoles were seen to be active, implying that all parts of the Dictyostelium contractile vacuole complex possess the ability to accumulate fluid and fuse with the plasma membrane. In contrast to observations reported for other types of cells, anti-calmodulin antibodies did not label the mitotic spindle in Dictyostelium. Despite this difference in localization, it is possible that vacuole-associated calmodulin in Dictyostelium cells and spindle-associated calmodulin in larger eukaryotic cells might perform a similar function, namely, regulating calcium levels.

Animals↗
PubMed1993

Vacuolar H(+)-ATPase of Dictyostelium discoideum. A monoclonal antibody study.

A Dictyostelium membrane fraction rich in vacuolar proton pumps, previously described by Nolta et al. (J. Biol. Chem. 266, 18,318-18,323, 1991), was used as the immunogen for production of monoclonal antibodies. We obtained antibodies that recognized polypeptides of 100 kDa and 68 kDa, corresponding to the two largest subunits of the vacuolar proton pump. In indirect immunofluorescence experiments, these two subunits were located on an interconnected collection of tubules and vacuoles. On frozen thin sections they were found principally on membranes of vacuoles and collections of small vesicles typically located just internal to the plasma membrane. These vesicles and vacuoles had electron-translucent lumens. No other structures in axenically grown Dictyostelium cells were labeled to a significant extent by these two antibodies. Using an affinity-purified antibody to calmodulin and a monospecific antibody to the B subunit of the chromaffin granule vacuolar ATPase, markers known to label the membranes of the contractile vacuole complex in Dictyostelium (Zhu and Clarke, J. Cell Biol. 118, 347-358, 1992; Heuser et al., J. Cell Biol. 121, 1311-1327, 1993), we showed that the 100 kDa and 68 kDa subunits had the same distribution as these two markers. Co-localization was seen in both interphase and mitotic cells. Thus, our results support the conclusion that vacuolar proton pumps are located principally on the membranes of the contractile vacuole complex in Dictyostelium. In addition, in indirect immunofluorescence experiments, these monoclonal antibodies provided improved images of the organization of the contractile vacuole system.

Animals↗
PubMed1993

Pulmonary embolus and maternal mortality in the antenatal period--evidence of a trend?

An analysis of pulmonary embolus mortality data was undertaken to investigate a putative change in maternal mortality due to pulmonary embolism in the antenatal period of pregnancy. A comparison was made of mortality due to pulmonary embolus for pregnant and non-pregnant women of reproductive age in England and Wales in the four triennia from 1976. During this period the antenatal pulmonary embolus mortality rate remained unchanged, whereas a statistically significant decline in non-pregnancy related pulmonary embolus mortality was observed. A comparison of the mortality trends between the two groups found the difference to be statistically highly significant. These findings strongly suggest that, over the twelve years investigated, women in the antenatal period of pregnancy have not benefited from the reduced risk of death from pulmonary embolus enjoyed by their non-pregnant counterparts.

England↗
PubMed1992

Social intervention and the elderly: a randomized controlled trial.

A randomized controlled trial was set up in 1985 to test the effect of social intervention over 3 years among elderly people, aged 75 and above, living alone. The sampling frame was the age/sex register of a large group practice of 12 general practitioners serving the town of Melton Mowbray, Leicestershire, England, with a list size of approximately 32,000 patients. A total of 523 elderly people living alone in 1985 were identified, interviewed, and randomized into experimental and control groups. A lay worker offered the experimental group (n = 261) individual packages of support that aimed at enhanced social contacts. The outcome measures, approximately 3 years later in 1988, were mortality; changes in physical status; demand for medical, paramedical, social, and voluntary services; and changes in a number of subjective variables (morale, loneliness, and self-perceived health). No significant differences were found for any of the variables with the exception of self-perceived health status, where the experimental group showed significantly greater improvements than did the control group. More importantly, half the elderly in this sample declined several offers of help.

Activities of Daily Living↗