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Biomedical subjects

G Ström

Publications and source records attributed to G Ström.

At least 19 recordsLinked to original sources
PubMed1995

Asthmatic symptoms and indoor levels of micro-organisms and house dust mites.

As a part of a worldwide investigation on the prevalence of respiratory symptoms, we have performed a study on the relationship between the indoor environment and asthma-like symptoms in the population of a central Swedish municipality. The study comprised 88 individuals, aged 20-45 years who underwent a structured interview, spirometry, a methacholine provocation test, skin-prick tests and blood samples for measurements of serum concentrations of eosinophil cationic protein (S-ECP), blood eosinophil count and total immunoglobulin E (S-IgE). In the homes, the room temperature, air humidity, respirable dust, house dust mites (HDM) and airborne micro-organisms were measured. The relative humidity in all the homes was found to be above 33%. HDM were found in 13% of homes. In the homes of the 47 subjects with asthma related symptoms, significantly higher total levels of bacteria and mould (P < 0.05) and a higher proportion of detected HDM (OR = 5.3) was found than in subjects with no asthma related symptoms, after adjustment for age, sex, smoking, indoor temperature and air humidity. HDM were found to be an independent risk factor for asthma related symptoms (OR = 7.9) and nocturnal breathlessness (OR = 6.2) (P < 0.05), while the total level of bacteria was a risk factor for asthma related symptoms and wheezing (P < 0.05). We conclude that although HDM is relatively infrequently found in the homes of central-Sweden, the presence of HDM is related to asthmatic symptoms. A relation between levels of airborne bacteria and asthma related symptoms was also found.

Adult↗
PubMed1995

Cardiovascular reactivity, Type A behavior, and coronary heart disease: comparisons between myocardial infarction patients and controls during laboratory-induced stress.

Cardiovascular responses to a series of laboratory stressors were examined in middle-aged Type A and Type B men. The subjects were 30 patients with diagnosed myocardial infarction (NYHA Class 1) and 26 age-matched healthy controls. All subjects were nonsmokers in the normotensive range, and none were on medication. Blood pressure, heart rate, forearm blood flow and resistance, and impedance cardiography-determined response variables were obtained during performance and recovery periods of both mental and physical tasks. The patients showed elevated reactivity in systolic blood pressure and cardiac output and prolonged systolic time ratio during mental stress tasks and elevated total peripheral resistance and lower cardiac output and stroke volume during physical tasks, as compared with control subjects. Thus, the difference in blood pressure reactivity between patients and controls appeared to be primarily dependent on the vascular component during physical tasks, whereas the mental tasks promoted a hemodynamic response pattern more consistent with beta adrenergic activation. Type A men, irrespective of coronary status, showed larger systolic and diastolic blood pressure response to both mental and physical stress than did Type B men.

Adult↗
PubMed1993

Thiols as peroxidase substrates.

The abilities of haem peroxidases to catalyse the oxidation of various thiols were studied using the spin-trapping electron spin resonance (ESR) technique. Myeloperoxidase, a neutrophil and monocyte enzyme, catalysed the oxidation of cysteamine, cysteine methyl, and ethyl ester and to some extent 2-mercaptoethanol and thioglycollic acid. This peroxidase poorly catalysed the oxidation of cysteine, N-acetylcysteine, penicillamine, and glutathione under the same conditions. The dependence on pH of peroxidase-catalysed thiol oxidation may indicate that the thiolate anion form is the actual peroxidase substrate. Another leucocyte peroxidase, eosinophil peroxidase, had similar catalytic properties toward thiols as myeloperoxidase. Lactoperoxidase (found in milk, saliva, and tears) and the plant horseradish peroxidase were, however, different from the aforementioned leucocyte peroxidases in their abilities to catalyse the oxidation of thiols.

Catalysis↗
PubMed1990

Evaluation of methods for enumerating microorganisms in filter samples from highly contaminated occupational environments.

Scanning electron microscopy (SEM), light microscopy (LM), epifluorescence microscopy (FM), and culture were used to assess catches of microorganisms in parallel air samples on membrane filters from heavily contaminated working environments that differed in the relative abundance of bacteria, actinomycetes, and fungal spores. Except in pig houses, estimates by SEM and LM were similar, but those by FM and culture were smaller. However, in pig houses, the fluorescent stain enabled bacteria on skin scales, not seen by SEM or LM, to be counted. Although counts obtained by culturing were always smaller than those obtained by SEM or LM, they sometimes exceeded those obtained by FM. Counts suggested that 0.1-68% of bacteria + actinomycetes and 3-98% of fungal spores were viable. However, samples for culturing may have contained larger aggregates than parallel samples collected within a sampling apparatus. All spore types recognized by LM included aggregates--those of bacteria + actinomycetes sometimes exceeding 200 units, while Wallemia sebi spore aggregates were never larger than 3 spores. The size distributions of all types approximated to log-normal, although single spores and small aggregates of bacteria + actinomycetes were perhaps underrepresented. When spores were counted directly on the filter surface, as by SEM and LM, allowance was necessary for heavier deposition of particles near the center of filters by distributing counting fields systematically over the whole filter or a sector of it. Deposition was more uniform in graphite-filled polypropylene filter holders used open-faced. Losses within filter holders and during transportation from sampling site to laboratory were small. The precision of counting spore-containing particles by LM and SEM was better than that of counting individual spores. No such difference was found for FM because many large spore-containing particles were dispersed during preparation.

Air Microbiology↗
PubMed1987

Separation of organic dust from microorganism suspensions by partitioning in aqueous polymer two-phase systems.

Conidia of Penicillium brevi-compactum and Aspergillus fumigatus, sporangiospores of Rhizopus rhizopodiformis, spores of Streptomyces griseus, and bacterial cells of Bacillus subtilis were partitioned in two-phase systems consisting of dextran, polyethylene glycol, substituted positively charged sulfonylpolyethylene glycol, and water. At a pH of 2.8 in the system, the microorganisms showed 60 to 90% affinity for the upper, polyethylene glycol-rich phase, except for cells of B. subtilis, which were entirely located in the lower, dextran-rich phase. This partition behavior was used to separate microorganisms in aqueous suspensions of peat, wood fuel chip, and straw samples from organic dust impurities prior to total count by acridine orange staining and epifluorescence microscopy. Only one extraction of the interphase and lower phase was needed to separate approximately 98% of the conidia of Penicillium chrysogenum from a suspension containing peat dust.

Bacteria↗
PubMed1986

Exercise during therapeutic beta-blockade: a two-year study in hypertensive patients.

The use of beta-adrenoceptor blocking drugs has been thought to impair physical performance. To test this statement, 12 patients with mild to moderate hypertension performed a submaximal exercise test during treatment with placebo and after 3 and 24 months of monotherapy with betaxolol, 20 to 40 mg daily. The resting heart rate and systolic and diastolic blood pressures were reduced after 3 months of treatment and the reduction was maintained 24 hours after the last dose at the 2-year visit. A 12% to 14% reduction of exercise-induced tachycardia was found, but blood pressure during exercise was reduced only in the patients with mild hypertension. However, in no patient did the working capacity decrease.

Adult↗
PubMed1986

Collection of airborne micro-organisms on Nuclepore filters, estimation and analysis--CAMNEA method.

The total number of airborne micro-organisms collected on Nuclepore filters was determined by acridine orange staining and epifluorescence microscopy. The viable fraction of the total numbers varied significantly when actinomycete and fungal spores from different environments were stored on the filter surface for 1 week, although the microflora composition was not altered. A high correlation between viable and total counts was noted in environments where the airborne flora was dominated by fungal spores, while a low correlation was found for airborne bacteria. Peak values of the total counts registered in some work environments varied between 10(7) and 10(11) micro-organisms/m3. Size analysis showed a dominating fraction of respirable micro-organisms (aerodynamical diameter less than 5 micron). The investigation shows that it is of the utmost importance to combine viable counts with total count enumeration in the study of exposure to micro-organisms in work-related situations.

Acridine Orange↗
PubMed1985

Arterial blood pressure and general sympathetic activation in essential hypertension during stimulation.

We asked whether exaggerated blood pressure (BP) reactivity in patients with essential hypertension (HT) is a sign of specific activation of the cardiovascular system or of generalized sympathetic activation. Fourteen patients with essential hypertension and 14 matched normotensive (NT) controls were subjected to tasks involving attentional demands, mental arithmetic, a cold pressor test and isometric muscular contraction. Systolic and diastolic BPs, skin and muscle blood flows, heart rate, skin conductance level and fluctuations during each task were recorded. Urine samples for determination of epinephrine and norepinephrine excretion were collected after task completion. All tasks caused BP increases in both groups. HT showed greater absolute and percentage BP reactivity than NT during isometric muscle contraction. Variables for which reactivity differences were observed were poorly correlated across tasks both in HT and NT, whereas resting values prior to each task were highly correlated in both groups. Skin conductance activity, epinephrine and norepinephrine excretion rates being examples of non-cardiovascular sympathetic nervous system (SNS) indicators did not separate HT from NT. Thus, the exaggerated pressor response in HT is not accompanied by signs of generalized SNS activation.

Blood Pressure↗
PubMed1984

Improved techniques for sampling airborne fungal particles in highly contaminated environments.

Nuclepore filters (polycarbonate) were compared with a slit sampler for the collection of airborne fungi particles. To enable high spore-concentration sampling, the slit sampler method was modified by the use of collection gels consisting of agar or glycerol/gelatin. The exposed gels were homogenized (agar) or melted (glycerol/gelatin), diluted, and spread on cultivation media. No significant difference was found between the Nuclepore filter method and the slit sampler method when glycerol/gelatin gels were used in the interval 10(3)-10(8) colony-forming units (cfu) per cubic meter. The lower trapping efficiency with agar gel was probably caused by water evaporating from the medium. The efficiency of a personal cascade impactor (Sierra) was compared with that of the Nuclepore filter method. The collection media used in the personal cascade impactor was modified for the determination of colony-forming units by moistening the collection filters with glycerol. The exposed filters were extracted with sterile water, and the suspension was diluted and spread on cultivation media. In trapping efficiency, the personal cascade impactor was similar to the Nuclepore filter method. The cut point of the personal cascade impactor showed high conformity with that of an Andersen sampler.

Air Microbiology↗
PubMed1984

Sampling of high concentrations of airborne fungi.

The paper discusses a method developed for determining airborne fungi particles in environments highly contaminated with mold fungi. The collection of airborne fungi was performed with two slit samplers. These sampling devices were found to give the highest values out of the three different types tested simultaneously. After spores had been collected with the slit samplers, the collection medium, an agar gel, was removed from the petri dishes and homogenized in a sterile 0.9% sodium chloride solution. The homogenate was diluted stepwise and spread on agar plates prior to the cultivation and the determination of viable counts. When the homogenization procedure was tested on samples collected from three different work environments, no increase or decrease in the number of colony-forming units could be detected. Storage of the homogenate at 2 degrees C over 9 d did not increase the number of viable fungal colonies.

Air Microbiology↗
PubMed1983

Muscle fibre composition in relation to blood pressure response to isometric exercise in normotensive and hypertensive subjects.

A positive relationship was demonstrated between the blood pressure and the fibre composition of the vastus muscle at rest in 17 hypertensive and 17 age- and sex-matched normotensive subjects. The hypertensive group had a higher proportion of fast twitch (FT) fibres (p less than 0.1). The circulatory response was measured during isometric exercise (IE) and cold pressor test (CPT). During IE the blood pressure increase was positively related to the percentage of FT fibres. No such relationship was demonstrated during CPT. It was thus found, particularly in hypertensive subjects, that an individual's muscle fibre profile is of importance for the blood pressure response during IE.

Adult↗