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Biomedical subjects

C Bullen

Publications and source records attributed to C Bullen.

At least 19 recordsLinked to original sources
PubMed2006

The effects of chemisorption on the luminescence of CdSe quantum dots.

We report on the effects of Lewis bases and other ligands on radiative recombination in CdSe quantum dots (QDs) in several solvents. Long-chain primary amines are found to be the most efficacious capping agents for CdSe QDs in nonpolar solvents. Primary alkylamines are superior to secondary and tertiary alkylamines. The kinetics of chemisorption and desorption in less polar solvents, such as hexane or chloroform, are temperature controlled and obey a Langmuir isotherm. Mercaptan adsorption also obeys a Langmuir isotherm, and alkylmercaptans rapidly displace amines, leading to luminescence quenching. In more polar solvents, such as toluene, ligands desorb, leading to luminescence quenching. It is proposed that surface Cd vacancies function as nonradiative recombination centers. The adsorption of a Lewis base to the QD raises the surface vacancy energy close to, or above, the conduction band edge and eliminates electron capture by the surface vacancies. Solvent polarity has a strong effect on luminescence since the solvent determines the extent of ligand adsorption to the QD surface.

Journal Article↗
PubMed2001

Presenting features of meningococcal disease, public health messages and media publicity: are they consistent?

AIMS: To investigate whether the presenting features of meningococcal disease as promoted in public health awareness material and in the print media accurately reflect the clinical features in patients admitted to Auckland hospitals with meningococcal disease January 1998 to June 1999. METHODS: Hospital record, public health message and newspaper article review, with analysis by presenting feature, age group and disease complex. RESULTS: The most common presenting features were fever (95%), rash (65%), vomiting and nausea (64%), lethargy (62%), headache (44%), refusing food and drink (35%), irritability (33%), muscle ache and joint pains (27%) and stiff neck (26%). Public health messages gave appropriate emphasis to the key features, whereas newspaper articles under-emphasised these. The term 'meningitis' was used more frequently in newspapers (65%) than in public health messages (30%), despite meningitis alone presenting less frequently (38% of cases) than meningococcal septicaemia, and having a less serious prognosis. CONCLUSIONS: Presenting features currently noted in the Ministry of Health's health education resource material are appropriate. Public health specialists dealing with the media should ensure that appropriate messages are incorporated into media reports. A greater use of the term 'meningococcal disease' by both public health agencies and media would convey to the public the message that this disease has a spectrum of presenting features, with those of septicaemia more common, but also indicating an even greater need for urgency of action than with 'classical' meningitic features.

Adolescent↗
PubMed2000

Taking public health to the streets: the 1998 Auckland Meningococcal Disease Awareness Program.

Since 1991, New Zealand has experienced a dramatic increase in cases of serogroup B meningococcal disease. Early in 1998, a program was initiated in Auckland to raise awareness among high-risk communities about the early clinical features of meningococcal disease and appropriate action to take. The campaign was conducted largely through door-to-door visiting by Maori and Pacific Islands lay educators, who visited more than 11,000 households and engaged more than 9,000 people in discussion. Significantly greater awareness was found in people visited by lay educators than those not visited. For the first time in 5 years, there were no meningococcal deaths among the target population for the 6 months from the start of the campaign. Home visiting by lay educators is an effective and highly acceptable means of communicating important health information to populations at high risk of meningococcal disease in New Zealand and should be considered for other public health campaigns.

Community Health Workers↗
PubMed1998

Cardiovascular disease risk factors in 65-84 year old men and women: results from the Auckland University Heart and Health Study 1993-4.

AIM: To describe the distribution of the major cardiovascular risk factors among older men and women in the Auckland region, New Zealand. METHODS: Means and prevalences of the major cardiovascular risk factors were estimated for non-Maori, non-Pacific Islands men and women in the age groups 65-74 and 75-84 years using data from the 1993-4 survey of the University of Auckland Heart and Health Study, a cross-sectional, population-based study of cardiovascular risk factors. RESULTS: 996 people aged 65-84 years participated, with men and women and the two ten-year age groups almost equally represented. Fewer than half engaged in regular leisure time physical activity; around 35% were overweight (BMI 25-30) and 10% were obese (BMI > 30). Total mean cholesterol levels were higher in women and 46% of women had a cholesterol level > or = 6.5 mmol/L compared with only 17% of men. However, total cholesterol:HDL ratios were higher among men. Age and sex differences in blood pressure were small. Around 50% had raised blood pressure (BP > 150/90) or were currently on antihypertensive medication; only 8% smoked; around 6% were diabetic. Almost 8% had three or all of four major modifiable cardiovascular risk factors (elevated blood pressure, total cholesterol:HDL ratio > or = 6.5, current smoking and physical inactivity). CONCLUSIONS: These results are broadly comparable to those from other Western populations. Differences between 65-74 and 75-84 year age groups are few but important differences in cholesterol, smoking and physical activity between older men and women are noted. These findings indicate that there is considerable potential for prevention of cardiovascular disease among older people.

Aged↗
PubMed1997

Ethnic differences in coronary heart disease case fatality rates in Auckland.

Data from the Auckland Coronary or Stroke (ARCOS) study for the years 1983 to 1992 were analysed to describe 28-day case fatality rates from coronary heart disease among Europeans, Maori and Pacific Islands people in Auckland, New Zealand. The case fatality rate was consistently higher in each age group and for both sexes among Maori and Pacific Islands people than in Europeans. Age-standardised case fatalities for Maori and Pacific Islands people were similar at around 65 per cent, compared with around 45 per cent among Europeans, and these differences were not explained by ethnic differences in possible underreporting of nonfatal myocardial infarction, in socioeconomic status, smoking, symptoms or past myocardial infarction. There was evidence of a more rapid progression of acute coronary events to a fatal outcome among Maori and Pacific Islands people, partly explained by delays in access to life support and coronary care: greater proportions of Pacific Islands people than Maori or Europeans who died did so within an hour of onset of symptoms (56 per cent of Pacific Islands people, 47 per cent of Maori, 45 per cent of Europeans). Pacific Islands and Maori people with acute coronary events took longer to reach a coronary care unit (mean times: Pacific Islands people 8.6 hours, Maori 7.4 hours, Europeans 6.7 hours, P < 0.05), although the median times were not significantly different; life-support units were used by a majority of Pacific Islands people and Europeans (57 per cent and 55 per cent, respectively), compared with only 46 per cent of Maori, but hospital care was similar for the three groups. Further qualitative and quantitative research is needed to investigate the reasons for these ethnic disparities in case fatality rates.

Adult↗
PubMed1996

Ethnic differences in blood pressure: findings from the Fletcher Challenge-Auckland University Heart and Health Study.

AIMS: To investigate the determinants of ethnic differences in blood pressure, hypertension and the prevalence of additional risk factors for cardiovascular disease among a New Zealand population. METHODS: Baseline data from the Fletcher Challenge-University of Auckland Heart and Health Study were analysed for ethnic differences in blood pressure, and the likelihood of those with hypertension having other major cardiovascular disease risk factors was estimated. RESULTS: Maori and Pacific Islands participants had mean diastolic blood pressure up to 3 mmHg higher than Europeans, but Pacific Islands people had mean systolic blood pressure 3-4 mmHg lower than Europeans and Maori respectively. After adjustment for age and gender almost 20% of Maori, 16% of Pacific Islands and 11% of European people were classified as hypertensive. Adjustment for body mass index and alcohol consumption almost eliminated ethnic differences in blood pressure, and body mass index was found to be the single most important modifiable determinant of raised blood pressure. Greater proportions of Maori (15%) and Pacific Islands people (14%) with hypertension had multiple additional cardiovascular risk factors compared with Europeans (8%), but similar proportions were on antihypertensive drug treatment. CONCLUSIONS: Efforts to reduce obesity have the potential to significantly reduce raised blood pressure among Maori and Pacific Islands people. Overall cardiovascular risk is more likely to be higher in Maori and Pacific Islands people than in Europeans with hypertension, indicating that greater proportions of Maori and Pacific Islands people with high blood pressure should be receiving treatment.

Adult↗
PubMed1993

A comparison of the laryngeal mask airway and Guedel airway, bag and facemask for manual ventilation following formal training.

Ten volunteers, with no previous experience of resuscitation, were formally trained in the use of the laryngeal mask airway and the oropharyngeal airway (Guedel), bag and facemask for manual ventilation of the lungs in 104 fit, anaesthetised adults. They then used both airways in turn. The order of insertion was randomly allocated, and the times taken for insertion were also recorded. Ventilation for each airway was deemed to be successful if an increase in end-tidal carbon dioxide partial pressure did not occur and arterial oxygen saturation remained greater than 90%. Success rates for the laryngeal mask airway and the Guedel airway, bag and facemask were 87% and 43% respectively (p < 0.001) and the average insertion times were 27.4 s (SEM 1.5) and 15.8 s (SEM 0.50) (no significant difference), respectively. The laryngeal mask airway proved to be easier to use for manual ventilation than the Guedel airway, bag and mask for inexperienced personnel who had received a period of formal training in both techniques.

Education, Nursing↗
PubMed1990

Renal replacement therapy in the ICU: the role of continuous arteriovenous haemodialysis.

Conventional haemodialysis is not available on all intensive care units (ICUs) and there are relatively few renally trained nurses able to run haemodialysis machines. Continuous arteriovenous haemodialysis provides effective renal replacement therapy for critically ill patients in the ICU. Unlike continuous arteriovenous haemofiltration it provides sufficient control over electrolyte, solute and water balance to obviate the need for additional treatment with intermittent conventional haemodialysis.

Acute Kidney Injury↗
PubMed1988

A severe coagulopathy following volume replacement with hydroxyethyl starch in a Jehovah's Witness.

Blood volume was maintained by an infusion of hydroxyethyl starch 2000 ml (Hespan: HES) during and for the first 28 hours after a major orthopaedic operation in a 13-year-old girl who was a Jehovah's Witness. This was responsible for a generalised clinical haemorrhagic state, an acquired coagulopathy associated with a shortened thrombin, prolonged prothrombin and activated partial thromboplastin times, and an acquired von Willebrand syndrome. The coagulation, after cessation of the infusion of HES, did not become normal until approximately 72 hours later.

Adolescent↗
PubMed1986

Conservative management of an impacted incisor.

There are several techniques available to the practitioner for the treatment of impacted, fully developed teeth. These techniques often involve surgical and/or orthodontic manipulation of the affected tooth. A more conservative approach was used in the case presented here, involving a boy who was 12 years 5 months old. An odontoma was surgically removed and the impacted tooth was allowed to erupt without the aid of external forces.

Child↗
PubMed1985

The haemostatic effects of hydroxyethyl starch (HES) used as a volume expander.

Hydroxyethyl starch (HES 450.000/0.7; Hespan 6.0 g/100 ml) was compared with standard crystalloid solutions in postoperative volume replacement in 20 patients undergoing routine orthopaedic surgery. The HES group showed no clinical evidence of haemorrhage and no laboratory evidence of significant haemostatic defects as assessed by standard coagulation tests, platelet aggregation and fibrinogen concentrations. There was a slight shortening in the thrombin time and a smaller increase in post-operative FVIII RAg and FVIII RCof levels in the HES group. HES is a safe and effective volume expander for postoperative use.

Adolescent↗