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H Harving

Publications and source records attributed to H Harving.

At least 19 recordsLinked to original sources
PubMed2005

House-dust mites and summer cottages.

BACKGROUND: Estimated indoor climate conditions in unheated summer cottages offers house-dust mites unfavorable temperature and feeding conditions while giving them optimum humidity conditions. We aimed to estimate the exposure level of house-dust mites in summer cottages. METHODS: A total of 37 summer cottages were sampled for house dust and storage mites in three locations and the results compared with samples from 33 patients suspected of house-dust mite allergy and living in ordinary houses. The processed dust samples were investigated by microscopy and exposure levels given as number of mites per 0.1 g dust. RESULTS: The summer cottages were without exception all heavily infested with threefold or higher concentrations of both house dust and storage mites in comparison with ordinary houses. In unheated summer cottages were found tropical high concentrations of house dust and storage mites with a median concentration of house-dust mites in mattress dust of 2000 house-dust mites/g of dust which corresponds to an average of 40 microg allergen/g of mattress dust. CONCLUSIONS: As a probable consequence of high indoor air humidity conditions in unheated summer cottages in winter, dust samples contained threefold or higher concentrations of house dust and storage mites. Indoor humidity conditions thus more than compensated for lack of continuous supply of skin scales from human beings and an unfavorable low indoor air temperature. The uniform high mite exposure in summer cottages is likely to imply disease deterioration in patients already allergic to mites.

Acaridae↗
PubMed1994

[Occurrence of housedust mites in dwellings. Relation to ventilation and humidity].

The concentration of house-dust mites (Der. spp.) was investigated in 96 Danish dwellings and bedroom air-exchange rates, humidity and temperature was measured contemporaneously in all the dwellings. A positive correlation was found between indoor air humidity and mite concentration, and an inverse correlation was found between house-dust mite concentration and indoor air-exchange. Dwellings of mite-allergic persons had a higher concentration of house-dust mites compared with those of the non-mite-allergic group. House-dust mite concentration was above the proposed limit in 76% of the homes of mite allergic persons and in 48% of the homes of non-sensitive persons. The high proportion of dwellings infested with house-dust mites, when compared with previous measurements, suggests an increased prevalence of house-dust mites in Danish dwellings. The results support the concept that reduced ventilation in dwellings involves a risk of increased house-dust mite exposure.

Air Pollution, Indoor↗
PubMed1994

Clinical efficacy of reduction in house-dust mite exposure in specially designed, mechanically ventilated "healthy" homes.

In temperate climates, energy-conserving measures may increase indoor humidity, enhancing house-dust mite (HDM) growth. Movement of families to "healthy" homes with mechanical ventilation systems reduced HDM exposure. The effect on asthma control of moving to the "healthy" homes was studied in 14 asthmatic patients allergic to HDM. Base-line evaluations of lung function, asthma symptoms, and medication requirements were made before moving and again after 5 and 15 months' residence. A control group of 11 mite-sensitive asthmatic patients who did not move were examined contemporaneously with the study group at base line and at the first follow-up investigation. After 5 months, the residents of the "healthy" homes improved in forced expiratory volume in 1 s (FEV1), medicine score, and serum IgE. These changes were significantly different from control group measurements. After 15 months, statistically significant improvements from base line were found in FEV1, average daily peak expiratory flow values, medicine score, symptom score, and serum IgE. Insignificant trends toward improvement were seen in provocation concentration of histamine and blood eosinophils. A significant relation was found between reduction in medicine score and fall in HDM exposure. The present study shows that a specific HDM-avoidance procedure can result in an overall, clinical improvement in HDM-sensitive asthmatic patients.

Adolescent↗
PubMed1994

House-dust mite exposure reduction in specially designed, mechanically ventilated "healthy" homes.

Exposure to house-dust mites (Dermatophagoides spp.) was investigated in 30 asthmatic patients before and after moving to homes with mechanical ventilation systems. Median house-dust mite concentration was 110 mites per gram of mattress dust at the initial investigation and 20 mites per gram at the first follow-up after a mean of 4.7 months in the new homes. This was lower (P < 0.05) than counts in a control group of 23 asthmatic patients that had unchanged counts. At a second follow-up, after 15.0 months, mite counts in the study group were further reduced (P < 0.01) from initial values. Among 16 patients, with initial mite counts above the recommended threshold limit value (TLV) of 100 mites per gram of dust, the mite counts fell, in most cases, below this TLV. Air-exchange rates increased (P < 0.001) from a median value of 0.40 air changes per hour (ach) to 1.52 ach at the second follow-up investigation. Furthermore, a reduction (P < 0.01) was found in indoor absolute air humidity, with a median value of 5.6 g of water/kg. No such changes were found in the control group. The present study indicates that reduction of air humidity through an increased supply of fresh air may significantly diminish and, in some cases, even eliminate house-dust mites in homes.

Air Conditioning↗
PubMed1993

House-dust mites and associated environmental conditions in Danish homes.

The concentration of house-dust mites (Dermatophagoides pteronyssinus) was investigated in 96 Danish homes with one or more members suffering from asthma. The air-exchange rates, humidity, and temperature were measured in all the homes. A positive correlation was found between indoor air humidity and mite concentration (P < 0.01), and an inverse correlation (P = 0.027) between house-dust mite concentration and indoor air-exchange was found. Homes of mite-allergic persons had a higher concentration of house-dust mites than did those of the non-mite-allergic group. House-dust mite concentration was above the proposed limit of 10 mites/0.1 g dust in 76% of the homes of persons allergic to mites and in 48% of the homes of nonsensitive persons. The high proportion of homes infested with house-dust mites suggests an increased prevalence of house-dust mites in Danish homes. The results support the concept that reduced ventilation in homes involves a risk of increased house-dust mite exposure.

Animals↗
PubMed1991

Measurement of PC20 histamine with the use of two different nebulizers and measurement of FEV1 and PEF.

Histamine challenge was performed in 19 patients using two nebulizers (PARI and Wright) and FEV1 and PEF were measured to determine PC20 histamine. FEV1 and PEF gave identical PC20 histamine values. The PARI nebulizer gave PC20 histamine values that were 2.5 doubling concentrations lower than the Wright nebulizer. The reproducibility of histamine challenge with the PARI nebulizer was studied in 15 patients and the results suggested that the challenge was reproducible within one doubling concentration of histamine.

Adolescent↗
PubMed1991

Lung function and bronchial reactivity in asthmatics during exposure to volatile organic compounds.

The purpose of the present study was to investigate whether vapors of organic solvents at low concentrations could exert an adverse effect in the lower airways. Under controlled conditions in a climate chamber, 11 persons with bronchial hyperreactivity to histamine and bronchial asthma were exposed for 90 min to a mixture of organic solvents at levels of zero, 2.5, and 25 mg/m3. During exposure to 25 mg/m3 a decrease in FEV1 to 90.7% of baseline value was measured. This was significantly different from the initial value (p less than 0.05), but not significantly different from the value found after sham exposure (FEV1, 97.4% of initial value). The decline in FEV1 during exposure to 25 mg/m3 was most pronounced in persons with high bronchial sensitivity. No changes were found in histamine reactivity after exposure, and no late reactions were registered. Ratings of discomfort showed different individual patterns ranging from no response to reactions towards both of the concentrations. The ratings indicated development of tolerance during exposure. Volatile organic compounds in concentrations found in both the work and the home environments may influence lung function and are probably of importance as bronchial irritants.

Adult↗
PubMed1990

Pulmonary function and bronchial reactivity in asthmatics during low-level formaldehyde exposure.

This study evaluated whether formaldehyde, at concentrations similar to those found in the indoor environment, could produce adverse effects on the lower airway of 15 asthmatic persons with documented bronchial hyperresponsiveness who were exposed for 90 min in a climate chamber to clean air containing formaldehyde vapor at levels of 0.85 mg/m3, 0.12 mg/m3, and 0.008 mg/m3. No significant changes in forced expiratory volume in 1 sec (FEV1), airway resistance (Raw), specific airway resistance (SRaw), and flow-volume curves could be detected during formaldehyde exposure. Furthermore, histamine challenge tests performed immediately after formaldehyde exposure showed no evidence of changes in bronchial reactivity. No late reactions were registered during the first 14-16 hr after exposure. The results suggest that residential levels of formaldehyde are of minor importance in the emergence of pulmonary symptoms. Discrepancies between the present study and previous data may be due to differences in environmental conditions.

Adolescent↗
PubMed1990

House dust mites and atopic dermatitis. A case-control study on the significance of house dust mites as etiologic allergens in atopic dermatitis.

The occurrence of house dust mites was measured in homes of 24 patients with atopic dermatitis, 30 patients with mite-sensitive asthma and 32 patients with asthma not related to house dust mites. Patients with mite-positive asthma and patients with atopic dermatitis had significantly higher exposure to house dust mites compared with patients with mite-negative asthma. For atopic dermatitis the higher exposure to house dust mites corresponded to a relative risk of 4.7 and a clear dose-response relationship was demonstrated between exposure and risk of disease in the subgroups of patients with atopic dermatitis. The present epidemiologic results support the idea that house dust mites may be an etiologic factor in a proportion of adult patients with atopic dermatitis.

Allergens↗
PubMed1989

Atopic dermatitis and the indoor climate. The effect from preventive measures.

Nine patients with atopic dermatitis (AD) were clinically evaluated before and after moving to new houses with improved air exchange, low relative humidity and optimal temperature control. During a 2-year period three clinical and subjective assessments were performed each month of disease activity, and compared with changes in suspended and respirable dust particles, room temperature, air exchange rate, concentration of house-dust mites in bedrooms, and the concentration of organic solvents in the indoor air. Ten matched patients with AD, who did not move, served as a control group. The skin condition of patients moved improved significantly after moving. The indoor climate was improved on: 1) air exchange rate, 2) relative humidity, and 3) room temperature, but the amounts of house dust mites, respirable air particles and organic solvents were unchanged. The clinical and subjective improvement in AD could not be correlated to any single indoor environmental factor. The present investigation supports the current concept, that AD may be a multifactorial disease, and that the indoor climate may be a contributing factor affecting the eczema.

Adolescent↗
PubMed1988

Terbutaline sustained-release tablets in nocturnal asthma--a placebo-controlled comparison between a high and a low evening dose.

The effects of oral treatment with terbutaline sustained-release (SR) tablets (Bricanyl Depot) were studied in nine patients who had bronchial asthma and marked diurnal variation in ventilatory function. In a randomized and double-blind study, the patients were treated with terbutaline SR 7.5 mg b.i.d., terbutaline SR 7.5 mg in the morning and 15 mg in the evening and terbutaline SR placebo b.i.d. Each treatment was given for 1 week. The nocturnal decline in the peak expiratory flow rate (PEFR) was 45% during the placebo period, 27% after the lower and 22% after the higher terbutaline SR evening dose (P less than 0.01 for both treatments compared to placebo). The mean morning PEFR was significantly higher with the high evening dose than with the low evening dose (P less than 0.01). Mild to moderate side effects were noted. The sustained-release preparation of terbutaline seems to be of clinical value in preventing or relieving nocturnal asthma and early morning dipping. The flexible dose technique, with a higher evening dose, results in further improvements in these patients.

Adult↗
PubMed1986

Red wine asthma: a controlled challenge study.

Drinking red wine may provoke bronchospasm in subjects with asthma. In order to reveal some of the possible agents involved in this reaction, 18 patients with a history of red wine-induced asthma were studied. They received, in a double-blind fashion, red wine with low sulfur dioxide (SO2) and high amine, high SO2 and high amine and low SO2 and low amine content. In each challenge, the wine was administered in stepwise increasing quantities until a total of 385 ml or a fall in peak expiratory flow of greater than 15% was reached. Nine subjects demonstrated a significant fall in peak flow in one or more challenges. In all cases the most severe reaction was observed after the wine with high SO2 content. The study suggests that SO2 is the most important factor in red wine-induced asthma. It is recommended that wine labels provide information on the SO2 content.

Adult↗
PubMed1985

Procaterol and terbutaline in bronchial asthma. A double-blind, placebo-controlled, cross-over study.

Procaterol, a new beta-2 adrenoceptor stimulant, was studied in a double-blind, placebo-controlled, cross-over trial in patients with bronchial asthma. Oral procaterol 50 micrograms b.d., procaterol 100 micrograms b.d., and terbutaline 5 mg t.i.d., were compared when given randomly in 1-week treatment periods. The best clinical effect was found with terbutaline. Both anti-asthmatic and tremorgenic effects of procaterol were dose-related. Procaterol appeared effective in the doses tested, and a twice daily regimen would appear to be suitable with this drug.

Adolescent↗