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Biomedical subjects

R W Siebers

Publications and source records attributed to R W Siebers.

At least 19 recordsLinked to original sources
PubMed2002

House dust mite allergen levels in university student accommodation in Dunedin.

AIM: To quantify the levels of Dermatophagoides pteronyssinus (Der p1) in different university student accommodation in Dunedin, and to assess relationships with housing characteristics and housekeeping practices. METHODS: Dwellings (n=178) were randomly selected from a database of first year university students in Dunedin. Dust samples were collected from both bed and the bedroom floor by standardised procedures. Der p1 levels were quantified by monoclonal antibody ELISA techniques. Details of housing characteristics, occupancy and housekeeping practices were obtained by questionnaire. RESULTS: Geometric mean (95% confidence intervals) Der p1 allergen levels from bedroom floors were: family homes (n=61) 5.58 (3.73-8.36) microg/g; student flats (n=43) 3.89 (2.49-6.07) microg/g; halls of residence (n=74) 0.26 (0.16-0.43) microg/g. Der p1 allergen levels from beds were: family homes 15.85 (9.78-26.57) microg/g; student flats 10.5 (6.41-17.19) microg/g; halls of residence 3.25 (2.33-4.54) microg/g. In all accommodation lower levels of Der p1 were found on the floor compared to the bed (p<0.005). Halls of residence had significantly lower Der p1 levels in both bed and floor (p<0.0005). Higher levels of Der p1 were associated with longer duration of occupancy, a history of condensation or mold in the accommodation, failure to use a hot wash for sheets, mattress age greater than one year and infrequent vacuuming of the bedroom floor. CONCLUSIONS: Wide variations in Der p1 levels were observed between different forms of student accommodation. Higher levels of Der p1 are found in family homes than in student flats or halls of residence.

Antigens, Dermatophagoides↗
PubMed1998

House dust mite allergen accumulation on sheepskins.

AIM: Sheepskins, which are often used as infant bedding in New Zealand, are known to harbour large quantities of house dust mites and their allergens. In this study we determined the rate of accumulation of the house dust mite allergen, Der p 1 on new sheepskins, and the effects of washing and dry cleaning on its removal. METHODS: New sheepskins were placed on living-room floors (n = 6) and mattresses (n = 6) in six domestic dwellings in Wellington. Sheepskin dust samples were collected by vacuuming before placement, and at two, four and six weeks, after which they were warm-washed. They were replaced for a further six weeks, then dry-cleaned. Dust samples were collected before and after washing and dry-cleaning, and from mattresses and living-room floors. Dust samples were analysed for Der p 1 by double monoclonal antibody ELISA. RESULTS: Der p 1 levels rapidly increased in sheepskins placed on living-room floors and mattresses to a geometric mean level (range) of 9.0 micrograms/g (1.1-102.2) and 29.4 micrograms/g (5.3-131.1) at six weeks, respectively. After warm-water washing and replacement for a further six weeks, these levels were higher at 75.5 micrograms/g (50.1-260.4) and 31.9 micrograms/g (11.1-75.2), respectively. Sheepskin Der p 1 accumulation correlated with mattress (r = 0.78), and living-room floor Der p 1 levels (r = 0.94). Warm water washing and dry-cleaning reduced sheepskins Der p 1 levels by a mean of 79.2% and 95.3%, respectively. CONCLUSIONS: Sheepskins rapidly accumulate house dust mite allergens from the domestic environment. Due to very high levels and rapid accumulation of Der p 1, sheepskins as infant bedding should be discouraged for infants at risk of sensitisation to house dust mites. If they are to be used then it is important that they are washed or dry-cleaned regularly.

Allergens↗
PubMed1997

The effect of frequent vacuum cleaning on the house dust mite allergen, Der p 1 in carpets: a pilot study.

AIM: To determine the effect of frequent vacuum cleaning of carpets on Der p 1, the major group one allergen of the house dust mite Dermatophagoides pteronyssinus. METHODS: Nine rooms and three hallways in the resident medical officers quarters at Wellington Hospital were regularly vacuum cleaned (daily, except weekends) over a five week period. Dust samples were collected before and at weekly intervals for Der p 1 measurement by a double monoclonal antibody ELISA technique. RESULTS: Der p 1 concentrations progressively declined from an initial geometric mean level (95% CI) of 4.47 micrograms/g fine dust (0.11-21.73) to 1.83 micrograms/g (0.29-9.57) after five weeks, a mean reduction of 48.0% (31.7-65.5). Similarly when expressed per unit area Der p 1 levels declined from 6.35 micrograms/m2 (1.15-35.16) to 1.66 micrograms/m2 (0.33-9.04), a mean reduction of 68.5% (58.6-78.3). CONCLUSIONS: Frequent vacuum cleaning over a short time significantly reduces house dust mite allergen levels in carpets. Larger long term trials are warranted to determine if greater reductions are possible that would be beneficial to house dust mite sensitive individuals.

Animals↗
PubMed1994

Increase in haematocrit in borderline hypertensive men.

1. Haematologic parameters were measured in untreated borderline hypertensive (BHT) men, and weight and age matched with normotensive men to determine whether previously described increased haematocrit (Hct) in established hypertension is evident in borderline hypertension. 2. Haematocrit was significantly increased in BHT men (mean 0.46, s.d. 0.032) compared with normotensive men (mean 0.43, s.d. 0.014) and correlated significantly with mean arterial pressure in this group (r = 0.67, P = 0.036) independent of weight. 3. The correlation of blood pressure with Hct in BHT men supports the concept that increased Hct may contribute to increased blood viscosity and thus to raised arterial pressure.

Adult↗
PubMed1994

Nebulized beta 2-adrenoceptor agonists do not affect plasma selenium or glutathione peroxidase activity in patients with asthma.

We investigated whether the beta 2-agonists fenoterol and salbutamol decreased plasma selenium and glutathione peroxidase activity in patients with asthma as this may partially explain the findings of reduced selenium status in asthmatic patients. Nine patients with asthma were studied on 3 occasions and inhaled either fenoterol (5 mg), salbutamol (5 mg) or ipratropium bromide (0.5 mg) administered by nebulization using a randomized, double blind, crossover design. Plasma selenium, glutathione peroxidase activity and potassium were measured prior to drug administration and at 15, 30 and 60 minutes after drug. None of the drugs had any effect on plasma selenium or glutathione peroxidase activity. Ipratropium bromide did not affect plasma potassium. Both beta 2-agonists significantly decreased plasma potassium. The mean (SD) maximum decrease was -0.79 (0-18) mmol/l for fenoterol and -0.26 (0-03) mmol/l for salbutamol (both p < or = 0.01) confirming systemic absorption of the drugs. beta 2-agonists are unlikely to be responsible for the reduced selenium status found in some patients with asthma.

Adrenergic beta-2 Receptor Agonists↗
PubMed1993

Nurses' attitudes and concerns pertaining to HIV and AIDS.

A pilot study was conducted to identify nurses' attitudes and concerns pertaining to the care of people with human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS). Data were collected using an anonymous, voluntary questionnaire, which was made available to all nurses at a Wellington Area Health Board (New Zealand) hospital. Of 562 nursing staff, 286 (51%) responded, of which 74 (25.9%) had previously attended an HIV/AIDS workshop for Area Health Board staff. Of those staff handling blood, 132 (49.4%) always wore gloves, and only half of the respondents (n = 148, 51%) treated all body fluids as potentially HIV positive. The possible attrition rate from nursing positions in the canvassed hospital was 2.8%, with a further 43 (15.0%) undecided about resigning from their post. Only 36 nurses (12.5%) believed the employer did not provide adequate safety measures. The provision of education regarding HIV/AIDS, by the employer, was considered inadequate by 61 (21.3%) respondents. This study demonstrates that further safety and education needs should be attended to or reinforced.

AIDS Serodiagnosis↗
PubMed1993

Transmembrane in vitro and in vivo sodium-lithium countertransport in New Zealand Maori.

1. Erythrocytic sodium-lithium (Na-Li) countertransport (CT) was measured in normotensive Maori and non-Maori by in vitro and in vivo methods to determine its relationship to erythrocytic hypernatraemia previously identified in Maori. 2. In vivo and in vitro CT rates were correlated within race and were similar between races. Countertransport rate was correlated with erythrocytic sodium concentration only in Maori. 3. The findings suggest the possibility of a genetically determined alteration in CT stoichiometry in Maori.

Adult↗
PubMed1992

Attitudes and concerns amongst laboratory staff regarding handling of HIV positive biological specimens.

AIMS: to ascertain attitudes and concerns of laboratory staff towards handling of HIV positive biological samples. METHOD: an anonymous questionnaire regarding various aspects of biological sample handling was distributed to laboratory staff from the Wellington Area Health Board laboratories. RESULTS: of a total of 133 laboratory staff (response rate: 56.4%), five were seriously considering leaving, and another ten would have chosen another career if given prior information in regard to handling HIV positive biological samples. Of the responders, 22.8% and 38.3% considered that their employer does not provide adequate safety measures and education respectively in regard to HIV. CONCLUSIONS: handling of HIV positive biological samples does not greatly contribute to attrition amongst laboratory staff. Given the concern of laboratory staff for safety and education in regard to HIV, a continuous in-service educational programme would be desirable.

Attitude of Health Personnel↗
PubMed1991

Lack of evidence for beta-2 receptor selectivity: a study of metaproterenol, fenoterol, isoproterenol, and epinephrine in patients with asthma.

In order to investigate the pharmacodynamic selectivity of a number of beta-receptor agonists currently used in asthma, we compared the pulmonary and extrapulmonary effects of repeated inhalations of epinephrine, fenoterol, isoproterenol, and metaproterenol in 12 patients with asthma in a randomized double-blind crossover study. The drugs were administered from metered-dose inhalers at 15-min intervals for five doses (total dose, 10 puffs of each compound). Measurements of heart rate, blood pressure, total electromechanical systole (as a measure of inotropic response), QTc interval, plasma potassium, and FEV1 were made 5 min after each dose and 30 min after the final dose. Fenoterol and metaproterenol had significantly greater inotropic, electrocardiographic, chronotropic, and hypokalemic effects than did both isoproterenol and epinephrine. There was no difference in the bronchodilating effect of metaproterenol, fenoterol, or isoproterenol although these agents caused a significantly greater increase in FEV1 than did epinephrine. The concept of increasing beta-2 selectivity for metaproterenol and fenoterol compared with isoproterenol are not supported in the clinical setting.

Adrenergic beta-Agonists↗
PubMed1991

Platelet indices: intra-individual variation in pre- and post-menopausal females.

Blood platelet counts and mean platelet volumes were determined at weekly intervals for eight weeks in 13 pre-menopausal and 11 post-menopausal females. Samples were analysed exactly two hours after blood collection on a Coulter S plus VTM particle counter. Pre-menopausal platelet counts were slightly higher than post-menopausal counts at each week, but the count was not affected by the menstrual cycle, intra-individual variation showing mean coefficients of variation (CV) of 7.4% and 5.2% respectively. The mean platelet volume was similar in pre- and post-menopausal groups at each week and showed little variability over time (mean CV 2.7% and 3.3%, respectively). Platelet parameters show little variability over time in either group and with no cyclical effects of menstruation apparent.

Blood Platelets↗