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Biomedical subjects

A C Walker

Publications and source records attributed to A C Walker.

At least 19 recordsLinked to original sources
PubMed2001

Potential role of endothelin receptor antagonists in the setting of cardiopulmonary bypass: relevance to myocardial performance.

The ET system is activated in cardiac surgical setting as evidenced by elevated systemic and myocardial ET-1 levels after coronary bypass grafting surgery which requires hypothermic cardioplegic arrest and cardiopulmonary bypass. Increased ET-1 may influence a number of clinical parameters in this setting. First, ET-1 may directly modulate myocardial contractile performance in the early postoperative period resulting in LV dysfunction and a complex postoperative course. Second, elevated ET-1 levels may exacerbate increased pulmonary vascular resistance and contribute to the development of transient pulmonary hypertension following bypass. Finally, augmented postoperative ET-1 levels could contribute to changes in the caliber and flow of vascular conduits used for coronary bypass. In this review, a current perspective on the ET system in the setting of cardiopulmonary bypass grafting surgery is provided and the potential use of ET receptor antagonists in this setting is discussed.

Animals↗
PubMed1997

Malnutrition and microcephaly in Australian aboriginal children.

OBJECTIVE: To examine the association between malnutrition and microcephaly in the first two years of life. DESIGN: Cross-sectional study. SETTING AND PARTICIPANTS: Royal Darwin Hospital (a tertiary referral centre); 157 of 165 previously studied Aboriginal children aged under two years who were admitted with diarrhoea between May 1990 and April 1991. Birth weight, birth length, birth head circumference, admission head circumference and admission nutritional status were examined. Nutritional status was categorised according to World Health Organization (WHO) criteria for wasting (thinness) and stunting (shortness). Microcephaly on admission was defined as a head circumference less than the second percentile on Australian reference charts. Small-for-gestational-age (SGA) and birth microcephaly were defined as being less than the tenth percentile for an Australian hospitalised population, corrected for gestational age at confinement. Low birth weight (LBW) was defined as less than 2500 g. MAIN OUTCOME MEASURE: Microcephaly on admission. RESULTS: Of the 157 children, 76 (48%) were wasted, 36 (23%) stunted and 37 (24%) microcephalic on admission. A total of 26 (17%) children had been of LBW, 17 (11%) SGA and 21 (13%) microcephalic at birth. On univariate analysis, microcephaly on admission was associated with wasting (crude odds ratio [OR], 3.91; 95% confidence interval [CI], 1.6-9.7; P < 0.005), but not stunting. There were no significant associations between microcephaly on admission and LBW, being SGA, microcephaly at birth, age or sex. With multivariate analysis, birth head circumference was significantly associated with microcephaly on admission (adjusted OR, 3.62; 95% CI, 1.28-10.23; P < 0.05), as was wasting (adjusted OR, 4.38; 95% CI, 1.88-10.20; P < 0.001). CONCLUSIONS: Wasting was significantly associated with microcephaly, independent of intrauterine growth retardation (as measured by being SGA) and LBW. As malnutrition in critical periods of both intra- and extrauterine development may have irreversible effects on intellectual potential and behaviour, the emphasis on improved nutrition must begin during pregnancy, and should continue in infancy and early childhood.

Analysis of Variance↗
PubMed1997

Helicobacter pylori serology and the management of young dyspeptics: a UK survey of gastroenterologists and general practitioners with an interest in gastroenterology.

AIM: To survey the current use of Helicobacter pylori serology for pre-endoscopy screening and management of young dyspeptics amongst gastroenterologists and general practitioners with an interest in gastroenterology in the United Kingdom. METHODS: A postal questionnaire was sent to 536 members of the British Society of Gastroenterology and 164 members of the Primary Care Society in Gastroenterology. RESULTS: Of those who responded (66%), 25% of general practitioners and 17% of gastroenterologists were using H. pylori serology as a screening test for young dyspeptics. General practitioners and gastroenterologists differed in their use of serology to guide management strategies (P < 0.0003): general practitioners eradicate infection from sero-positive patients prior to endoscopy (92%), whilst the majority of gastroenterologists endoscope sero-positive patients before treatment (55%). More gastroenterologists (89%) would re-test all or selected patients to assess eradication compared to general practitioners (45%). 106 different drug regimes were being used as first line treatment. CONCLUSIONS: H. pylori serology as a pre-endoscopy screening test for young dyspeptic patients was used by only a fifth of respondents. There were wide variations in attitudes and practice in the way H. pylori serology was used in the management of young dyspeptics. Trials comparing clinical outcome and cost-effectiveness of different serology-based strategies are needed.

Adult↗
PubMed1996

The 'expert' nurse comforter: perceptions of medical/surgical patients.

An interpretative study of Australian adult medical-surgical patients' experiences and perceptions of comfort and discomfort in hospital uncovered a number of themes. One theme, patients' perceptions of and experiences with nurses they called 'good' or 'expert', is the subject of this paper. Informants provided brief vignettes of 'expert' nurses and glimpses of skilled nursing that depicted nurses as important sources of comfort and well-being. Nurses who 'knew what they were doing' in intensive care units and in high-dependency, medical-surgical, postnatal and short-stay wards were reassuring, caring and 'expert'. Informants' descriptions of expert nursing are briefly compared with descriptions found in the professional nursing literature. Because nursing work is poorly understood and because it is immensely comforting for patients to know that nurses are both competent and caring, nursing comfort and safety work deserve to have a higher profile in the public perception of nursing.

Adult↗
PubMed1995

Malnutrition among rural aboriginal children in the Top End of the Northern Territory.

OBJECTIVE: To calculate the minimum prevalence of malnutrition among rural Aboriginal children under two years of age in the Top End of the Northern Territory (NT) using World Health Organization (WHO) criteria. METHODS: We calculated weight-for-height and height-for-age Z-scores (WHO-endorsed references) for all children under two years who were admitted to hospital with diarrhoeal disease between May 1990 and April 1991. Weights recorded 48 hours after admission were used to allow for acute dehydration. Malnutrition was defined in terms of "wasting" and "stunting" when weight-for-height and height-for-age were more than two standard deviations below the median of the WHO reference population. The denominator population was calculated from NT Department of Health and Australian Bureau of Statistics data. RESULTS: From an average population of no more than 480 children under two years, 34% were admitted to hospital at least once with diarrhoeal disease in the 12 months; 59% were malnourished (wasting alone, 36%; stunting alone, 10%; both, 13%). In the study period an estimated minimum of 20% of all Aboriginal children in the Top End were malnourished (wasted, 12%; stunted, 3%; both, 5%). CONCLUSIONS: The 20% prevalence of malnutrition is many times higher than would be expected statistically, and higher than in many underdeveloped countries. International relief agencies regard a prevalence of wasting in children of more than 8% as a nutritional emergency. We urge that programs to alleviate the poor socioeconomic conditions, and mechanisms for early detection and intervention in childhood malnutrition, be offered to Aboriginal communities.

Diarrhea, Infantile↗
PubMed1995

Impact of culture on pain management: an Australian nursing perspective.

Pain assessment and pain management are complex tasks. Knowledge and beliefs of patients, physicians, and nurses about pain are key determinants of clinical decision making. Despite new theoretical insights, routine approaches to pain assessment and management persist in practice. Culture is a potent force in shaping beliefs, behavior, and meaning about pain. In health care contexts, there may be conflict between care and cure and differing perceptions about the role and status of nurses that impinge on the provision of pain relief. The article explores aspects of culture, knowledge, and belief and their influence on pain management from an Australian perspective.

Attitude of Health Personnel↗
PubMed1995

Diagnosing idiopathic dystonia: must it take so long?

Idiopathic dystonia is a chronic, disabling movement disorder. This study attempted to verify anecdotal evidence that sufferers experience delay in achieving a correct diagnosis. A survey of 133 patients revealed that diagnosis after first seeking help required a mean of 3.8 years. Diagnostic latency varied considerably, with 22 per cent of respondents reporting a diagnostic latency of more than five years, while a further 22 per cent reported a latency of one month or less, with a sample median of 1.5 years. Respondents consulted a mean of 8.3 practitioners, including a mean of 2.1 general practitioners and 1.6 neurologists. Results were consistent with reports of lengthy diagnostic delays and inappropriate referrals. Greater awareness of dystonia and referral of suspected cases to a neurologist interested in movement disorders are recommended.

Adolescent↗
PubMed1993

Hominid radius from the middle Pliocene of Lake Turkana, Kenya.

A nearly complete left radius, KNM-ER 20419, was recovered from middle Pliocene sediments east of Lake Turkana, Kenya in 1988. Ape-like characteristics of the fossil include an eccentrically positioned articular fovea, relatively long radial neck, wide distal metaphysis, and large brachioradialis crest. The robustness of the radial neck in proportion to the radial head, and the semilunar shape of the distal diaphysis, however, clearly distinguish KNM-ER 20419 as hominid. The distal articular surface possesses a larger area for radius-lunate articulation than for radius and scaphoid, a radiocarpal arrangement that is associated with increased wrist adduction among quadrumanous climbers. Since this morphology is also found in hylobatids, Pongo, and other early australopithecines, it is argued to be plesiomorphic for hominoids. This further supports the argument that vertical climbing was an important locomotor behavior among both early hominoids and our more immediate prebipedal ancestors.

Animals↗
PubMed1991

Similarities in Aegyptopithecus and Afropithecus facial morphology.

Recently discovered cranial fossils from the Oligocene deposits of the Fayum depression in Egypt provide many details of the facial morphology of Aegyptopithecus zeuxis. Similar features are found in the Miocene hominoid Afropithecus turkanensis. Their presence is the first good evidence of a strong phenetic link between the Oligocene and Miocene hominoids of Africa. A comparison of trait lists emphasizes the similarities of the two fossil species, and leads us to conclude that the two fossil genera share many primitive facial features. In addition, we studied facial morphology using finite-element scaling analysis and found that the two genera show similarities in morphological integration, or the way in which biological landmarks relate to one another in three dimensions to define the form of the organism. Size differences between the two genera are much greater than the relatively minor shape differences. Analysis of variability in landmark location among the four Aegyptopithecus specimens indicates that variability within the sample is not different from that found within two samples of modern macaques. We propose that the shape differences found among the four Aegyptopithecus specimens simply reflect individual variation in facial characteristics, and that the similarities in facial morphology between Aegyptopithecus and Afropithecus probably represent a complex of primitive facial features retained over millions of years.

Animals↗
PubMed1989

Rheumatic heart disease in aboriginal children in the Northern Territory.

Data on 33 Aboriginal children with rheumatic heart disease who attended the Royal Darwin Hospital over a four-year period were examined. Mitral-valve incompetence was the most-common valvular lesion that occurred as a result of rheumatic heart disease and was present in 30 children. Mitral stenosis was present in 17 children and was accompanied by incompetence in all cases; it was present by the age of 13 years in more than half the children. Five children died in the period of the study and four of these had mitral stenosis as part of their valvular abnormality. Rheumatic heart disease is a significant cause of morbidity and mortality in Aboriginal children in the Northern Territory.

Adolescent↗
PubMed1988

Morphology of Turkanapithecus kalakolensis from Kenya.

The type specimen of Turkanapithecus kalakolensis recently recovered from northern Kenya preserves a partial cranium and mandible. This specimen, together with postcranial elements that are probably associated with it, and two additional specimens are described. The collection is compared with other Miocene hominoids.

Animals↗
PubMed1988

Morphology of Afropithecus turkanensis from Kenya.

Forty-six specimens of a large Miocene hominoid, Afropithecus turkanensis, recently recovered from northern Kenya preserve many morphological details that are described. The specimens include cranial, mandibular, and postcranial parts. They are compared briefly with other Miocene hominoids. It is suggested that Afropithecus may have affinities with Heliopithecus, Kenyapithecus, and the large hominoid from Moroto and Napak, although it is noted that the comparative material is limited in the number of common anatomical parts preserved.

Animals↗
PubMed1986

Low birthweight and mortality in Australian Aboriginal babies at the Royal Darwin Hospital: a 15 year study.

A retrospective analysis was made of all births at the Royal Darwin Hospital from 1 January 1969 to 31 December 1983. The births were divided into weight categories and racial groups (Aboriginal and non-Aboriginal). The study showed that there was a 23.2% incidence of low birthweight (LBW) babies (less than 2500 g) in Aboriginals compared with an incidence of 6.4% in non-Aboriginals. It was found that Aboriginals had a better chance of surviving the neonatal periods than non-Aboriginals of the same birthweight for all birthweights up to 2500 g. It is suggested that this occurred because most LBW Aboriginals were more mature than their birthweight would have suggested. The perinatal and neonatal mortality, however, remains high in the Aboriginal babies and this can also be attributed to the high incidence of LBW babies in this group, and perhaps to the limited use of antenatal care by the Aboriginal mothers.

Australia↗
PubMed1986

Reactions to radiographic contrast media: an attempt to detect specific anti-contrast medium antibodies in the sera of reactor patients.

A radioimmunoassay was used in an attempt to detect specific anti-contrast medium antibodies in the sera of a group of 68 patients who reacted to radiographic contrast media and a group of 30 age-, sex- and disease-matched control patients who did not react. No evidence of specific antibodies of the IgG or IgE classes was demonstrated in these two groups. The results suggest the lack of an antibody-mediated aetiology for reactions to radiographic contrast media.

Antibodies↗
PubMed1984

Kinin activation as a predictive assay for adverse reactions to radiographic contrast medium.

The rate of conversion in vitro, of prekallikrein to kallikrein has been measured in 74 reactors to contrast medium and 70 controls. The conversion rate is significantly more rapid in reactors than controls. There was no difference in C1-esterase inhibitor and factor XII levels between reactors and controls. This retrospective investigation suggests that prekallikrein/kallikrein conversion rate may form the basis of a test for differentiating between reactors and non-reactors.

Adolescent↗