PubMed Health⌕ Search

Biomedical subjects

N van der Merwe

Publications and source records attributed to N van der Merwe.

6 recordsLinked to original sources
PubMed2000

The hunters and the hunted revisited.

The dietary niches of extinct animals, including hominids and predators, may be constrained using stable carbon isotope ratios in fossil tooth enamel.(13)C/(12)C ratios of many of the primates abundant in the faunal assemblages of Members 1 and 2 at Swartkrans, including cercopithecoids and Australopithecus (Paranthropus) robustus, and a range of other possible prey species, have been reported previously. Resulting suggestions of a mixed, or omnivorous, diet for A. robustus raise questions about niche overlap with coeval, larger brained Homo. Here we present(13)C/(12)C data from Homo and several large predators including Panthera pardus, Dinofelis sp., Megantereon cultridens and Chasmoporthetes nitidula in Member 1, and P. pardus and P. leo in Member 2, in order to compare the two hominid species and to determine likely predators of the various primates and other macrovertebrates. Results for three Homo cf. ergaster individuals are indistinguishable from those of A. robustus, showing that proportions of C(3)- and C(4)-based foods in their diets did not differ. P. pardus, Megantereon and Crocuta are shown to be likely predators of the hominids and Papio baboons in Member 1, while the Dinofelis individual concentrated on prey which consumed C(4)grasses. The hunting hyaenid C. nitidula preyed on either mixed feeders or on a range of animals across the spectrum of C(3)and C(4)variation. The data from Members 1 and 2 confirm a shift in leopard diets towards animals that consumed C(4)grasses.

Animals↗
PubMed1999

The use of a rating instrument to teach and assess communication skills of health-care workers in a clinic in the Western Cape.

Research in health communication shows communication to be an important aspect of successful health-care. Moreover, training courses which provide feedback have been shown to improve health professionals' ability to conduct successful interviews. This article describes a rating instrument which was developed in order to facilitate teaching and assessing the communication aspects of health-care interviews. The instrument was found to be useful in a training programme offered to nursing staff of a TB Clinic in Mitchells Plain, Western Cape. The instrument appears as Table 1. In the Table categories of communication behaviours, each indicating an important aspect of the interaction, are given as the six headings. These are: establishing rapport and respect listening receptively confirming the patient sharing control informing effectively and checking perceptions. Within each category the more detailed specific behaviours are listed, allowing for close analysis of a care-giver's interviewing skill. The article briefly discusses the importance in effective communication between the care-giver and patient of each category of behaviours given in the instrument, supported by evidence from research. Lastly the article describes a "case study" on how the instrument has been successfully used in a training programme.

Clinical Competence↗
PubMed1997

Communication with TB patients; a neglected dimension of effective treatment?

Previous research has shown that patients who are satisfied with their interactions with a health provider tend to adhere to treatment. This study sets out to investigate the quality of the communication in the interactions between clinic nurses at a Western Cape clinic and newly notified tuberculosis patients. Routine interviews between clinic nurses and tuberculosis patients were video-recorded, transcribed and analysed, using a qualitative instrument devised by the researchers. The interactions were evaluated as being essentially nurse-centred; there was an unequal distribution of control, poor receptivity to the patient and little confirmation of the patient. The nursing staff received a period of training in communication skills. After this training their interviews with patients revealed a significant shift towards a more patient-centred approach, resulting in mutual satisfaction of nurse and patient. Training in communication skills should be introduced at TB clinics, in order to improve patients' adherence to therapy.

Analysis of Variance↗
PubMed1987

Mitochondrial Ca2+ fluxes and levels during ischaemia and reperfusion: possible mechanisms.

It has been shown that myocardial ischaemia depresses the uptake and enhances the release of Ca2+ by mitochondria. Reperfusion of the ischaemic areas may result in a further deterioration of the above processes. Despite these marked changes in Ca2+ fluxes, reperfusion has been shown always to be associated with a marked increase in mitochondrial Ca2+ content. To explain the latter observation, it has been proposed that reperfusion promotes respiration-supported mitochondrial Ca2+ uptake in preference to ADP phosphorylation. To evaluate this hypothesis, the effect of exogenous ADP on mitochondrial respiration-linked Ca2+ uptake was investigated in control, ischaemic and ischaemic-reperfused hearts. The results show that ADP significantly depresses mitochondrial Ca2+ uptake in all three preparations, indicating that Ca2+ is not taken up preferentially to ADP phosphorylation in reperfused tissue. It is suggested that reperfusion-induced increased mitochondrial Ca2+ levels are probably not due to increased respiration-linked Ca2+ uptake, but rather to augmented conversion of ionized Ca2+ to calcium phosphate which does not participate in ionic fluxes.

Adenosine Diphosphate↗
PubMed1985

Mitochondrial phospholipid composition and microviscosity in myocardial ischaemia.

Normothermic ischaemic arrest of the isolated perfused rat heart causes profound changes in mitochondrial ultrastructure. Since the mitochondrial membranes contain a high percentage of phospholipids, an evaluation of the effect of different periods of ischaemia on mitochondrial phospholipid content and fatty acid composition was made. The results showed that ischaemia had no effect on the content of the different phospholipid classes and no correlation was observed between ultrastructural changes and mitochondrial phospholipid content. However, the phospholipid fatty acid composition of several phospholipids showed marked changes. For example, with lysophosphatidylcholine a progressive increase in the percentage saturated fatty acids was observed with increasing periods of ischaemia, while a reduction occurred in lysophosphatidylethanolamine. To determine whether the ischaemia-induced changes in mitochondrial phospholipid fatty acid composition had an effect on the physical properties of the membrane, the microviscosity of mitochondrial preparations was studied, using the lipophilic probe, 1,6-diphenyl-1,3,5-hexatrine. Mitochondria isolated from ischaemic hearts showed a progressive increase in fluorescence polarization with longer periods of ischaemia, indicating an overall increase in microviscosity. This phenomenon may be responsible for the increased mitochondrial fragility which is characteristic of ischaemic damage.

Animals↗