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Biomedical subjects

G Blomquist

Publications and source records attributed to G Blomquist.

At least 19 recordsLinked to original sources
PubMed2006

Inhibition of acetylcholinesterase in CSF versus brain assessed by 11C-PMP PET in AD patients treated with galantamine.

The relationship between acetylcholinesterase (AChE) activity in the CSF and brain of patients with Alzheimer's disease (AD) was investigated in 18 mild AD patients following galantamine treatment. The first 3 months of the study had a randomized double-blind placebo-controlled design, during which 12 patients received galantamine (16-24 mg/day) and six patients placebo. This was followed by 9 months galantamine treatment in all patients. Activities and protein levels of both the "read-through" AChE (AChE-R) and the synaptic (AChE-S) variants in CSF were assessed in parallel together with the regional brain AChE activity by (11)C-PMP and PET. The AChE-S inhibition was 30-36% in CSF, which correlated well with the in vivo AChE inhibition in the brain. No significant AChE inhibition was observed in the placebo group. The increased level of the AChE-R protein was 16% higher than that of AChE-S. Both the AChE inhibition and the increased level of AChE-R protein positively correlated with the patient's performance in cognitive tests associated with visuospatial ability and attention. In conclusion, AChE levels in CSF closely mirror in vivo brain AChE levels prior to and after treatment with the cholinesterase inhibitors. A positive cognitive response seems to dependent on the AChE inhibition level, which is balanced by an increased protein level of the AChE-R variant in the patients.

Acetylcholinesterase↗
PubMed2001

Dampness in buildings and health. Nordic interdisciplinary review of the scientific evidence on associations between exposure to "dampness" in buildings and health effects (NORDDAMP).

Several epidemiological investigations concerning indoor environments have indicated that "dampness" in buildings is associated to health effects such as respiratory symptoms, asthma and allergy. The aim of the present interdisciplinary review is to evaluate this association as shown in the epidemiological literature. A literature search identified 590 peer-reviewed articles of which 61 have been the foundation for this review. The review shows that "dampness" in buildings appears to increase the risk for health effects in the airways, such as cough, wheeze and asthma. Relative risks are in the range of OR 1.4-2.2. There also seems to be an association between "dampness" and other symptoms such as tiredness, headache and airways infections. It is concluded that the evidence for a causal association between "dampness" and health effects is strong. However, the mechanisms are unknown. Several definitions of dampness have been used in the studies, but all seems to be associated with health problems. Sensitisation to mites may be one but obviously not the only mechanism. Even if the mechanisms are unknown, there is sufficient evidence to take preventive measures against dampness in buildings.

Air Pollution, Indoor↗
PubMed2001

Airborne chemical compounds on dairy farms.

The chemical environment that dairy farmers are exposed to during milking was investigated. Volatile organic compounds (VOCs) were analysed and identified, and the levels of formaldehyde, ammonia and carbon dioxide were measured in eight farms in northern Sweden. Both stationary and personal samples were taken. A total of 70 VOCs were identified from the adsorbent samples, with p-cresol, 2-butanone, ethyl acetate, alpha-pinene and delta 3-carene occurring at the highest levels. All monitored levels were significantly lower for compounds having a stated highest occupational exposure level (OEL). Using multivariate techniques some differences in the composition of the workplace air between and within the farms were found. No difference was found between personal exposure and the surrounding environment in the cowshed.

Agriculture↗
PubMed2001

Recognition errors in the quantification of micro-organisms by fluorescence microscopy.

OBJECTIVES: An interlaboratory comparison of fluorescence microscopic counting of micro-organisms was carried out to assess counting errors in the measurement of micro-organisms in bioaerosols generated during handling of municipal waste. METHODS: Series of 27 replicate samples were collected in the work environment with a modified field exposure chamber. The preparation methods of three Scandinavian laboratories were compared. Four microscopists from these laboratories performed the counts which were also compared. Duplicate counting of identical microscopic fields allowed the assessment of recognition errors. RESULTS: The field exposure chamber collected replicate samples with a relative standard deviation of 5% when particles < or = 15 microm aerodynamic diameter were collected. Storage time of 40-200 days had no significant influence on the total micro-organism count. Differences between preparation methods were from 2 to 35% for bacteria, and from 15 to 35% for fungal spores when samples were analysed in Oslo; the results for fungal spore counts were significantly different (P < 0.01). These differences were not confirmed when samples were analysed in Umeå, Copenhagen and Oslo using those laboratories methods. These results can be explained by less efficient redispersion of aggregates when the Umeå and Copenhagen methods were recreated in Oslo yielding a greater number of innumerable aggregates. Differences between microscopists were minor for fungal spores (2-12%) but substantial for bacteria (4-53%). A major source of error was the recognition of bacteria which had a relative standard deviation (rsd) of 37% although a lower size limit of 0.75 microm was adopted for counting of bacteria. Fungal spores were recognised with much better precision (rsd 9%). CONCLUSIONS: Recognition errors of bacteria may be substantial and more specific fluorochromes are needed for fluorescence microscopic counting of micro-organisms.

Analysis of Variance↗
PubMed1999

Air sampling of fungal spores on filters. An investigation on passive sampling and viability.

In this study, glycerol was tested as a collection substrate for passive bioaerosol sampling. Filters (mixed cellulose acetate and nitrate) were soaked in glycerol and exposed for an aerosol from three different fungal species: Penicillum commune, Aspergillus versicolor and Paecilomyces variotii. The passive sampling method was compared with a closed-face polycarbonate filter sampling method. Exposure was performed in an exposure chamber. The total number of spores was determined by microscopic techniques, and the cultivable number was determined by cultivation on Malt Extract Agar dishes. The glycerol soaked filter demonstrated a good correlation with the closed-face sampler with regard to the total count. Spores stored in a pumped filter cassette were not affected by storage for up to 7 days. On the other hand, the culturability of the spores was markedly decreased after 1 day when stored on glycerol soaked filters.

Aerosols↗
PubMed1996

Volatile metabolites produced by two fungal species cultivated on building materials.

Two fungal species commonly found in indoor environments, Penicillium commune and Paecilomyces variotü, were cultivated on pine wood and on a combination of gypsum board and mineral wool. Air from the cultures was adsorbed on Tenax TA and analysed using thermal desorption-cold trap injection gas chromatography. Identification of the produced volatile metabolites was performed by mass spectrometry. The majority of the compounds produced were alcohols, ketones, ethers and terpenoid compounds. Commonly produced metabolites were 2-methyl-1-propanol, 3-methyl-1-butanol, 1-hexanol, 2-heptanone, 2-pentanone and 2,5-dimethyl-furan. The production was highly influenced by both medium and species.

Construction Materials↗
PubMed1995

Identification of volatile metabolites from five fungal species cultivated on two media.

Five fungal species, Aspergillus versicolor, Penicillium commune, Cladosporium cladosporioides, Paecilomyces variotii, and Phialophora fastigiata, were cultivated on two media, malt extract agar and dichloran glycerol agar. Culture flasks provided with inlet and outlet tubes were used and purified, and humidified air was constantly led through the flasks. Air samples from the cultures were sorbed on Tenax GR and analyzed by thermal desorption-gas chromatography. The produced volatile metabolites were analyzed by mass spectrometry. Various hydrocarbons, alcohols, ketones, ethers, esters, sulfur-containing compounds, and terpenes were identified. The most commonly produced substances were 2-methyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methylfuran, and dimethyl disulfide. The production was highly dependent on both medium and species.

Journal Article↗
PubMed1994

Sampling of biological particles.

Sampling strategy, sampling and analysis of different biological particles, mainly fungal spores and bacteria, are reviewed. The sampling is strongly dependent on the environment, time of year and activity at the workplace. The choice of suitable sampling equipment depends on the levels of airborne micro-organisms. For sampling in non-industrial indoor environments (< 10(6) micro-organisms m-3), slit samplers, cascade impactors and multistage impingers can be used. At high concentrations of airborne micro-organisms (> 10(6) micro-organisms m-3), other types of methods must be used because the slit samplers and cascade impactors, such as Andersen samplers, are often overloaded. Sampling using polycarbonate filters is one method that can be used. Other useful methods are, for example, multistage liquid impingers or an Aerojet General Glass Cyclone. Analysis of the filter by cultivation gives lower values than microscopy. Direct analysis of the filter by scanning electron microscopy results in values that are 2-3 times higher than those obtained by analysis using Acridine Orange staining and epifluorescence microscopy. Suspension of biological particles in liquid before microscopic analysis results in the observation of more single spores, which suggests that large spore aggregates break down during suspension.

Air↗
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↗
PubMed1989

Kinetic analysis of central [11C]raclopride binding to D2-dopamine receptors studied by PET--a comparison to the equilibrium analysis.

[11C]Raclopride binding to central D2-dopamine receptors in humans has previously been examined by positron emission tomography (PET). Based on the rapid occurrence of binding equilibrium, a saturation analysis has been developed for the determination of receptor density (Bmax) and affinity (Kd). For analysis of PET measurements obtained with other ligands, a kinetic three-compartment model has been used. In the present study, the brain uptake of [11C]raclopride was analyzed further by applying both a kinetic and an equilibrium analysis to data obtained from four PET experiments in each of three healthy subjects. First regional CBV was determined. In the second and third experiment, [11C]-raclopride with high and low specific activity was used. In a fourth experiment, the [11C]raclopride enantiomer [11C]FLB472 was used to examine the concentration of free radioligand and nonspecific binding in brain. Radio-activity in arterial blood was measured using an automated blood sampling system. Bmax and Kd values for [11C]raclopride binding could be determined also with the kinetic analysis. As expected theoretically, those values were similar to those obtained with the equilibrium analysis. In addition, the kinetic analysis allowed separate determination of the association and dissociation rate constants, kon and koff, respectively. Examination of [11C]raclopride and [11C]FLB472 uptake in brain regions devoid of specific D2-dopamine receptor binding indicated a fourth compartment in which uptake was reversible, nonstereoselective, and nonsaturable in the dose range studied.

Adult↗
PubMed1987

The normal pituitary examined with positron emission tomography and (methyl-11C)-L-methionine and (methyl-11C)-D-methionine.

Four patients with radiologically normal pituitary gland were examined with positron emission tomography after the administration of (methyl-11C)-L-methionine. On a following day the examination was repeated with (methyl-11C)-D-methionine. The accumulation rate of L-methionine in the pituitary was measured, giving a value that was about twice that of normal brain tissue. The accumulation rate of D-methionine in the pituitary was almost a factor of 10 lower than that of L-methionine. In the normal brain tissue that ratio was 2.3. The study clearly indicates that the methionine uptake in the pituitary is stereospecific. 11C-D-methionine is freely distributed in the tissue without entrapment, whereas 11C-L-methionine is irreversibly bound. It is concluded that PET with 11C-L-methionine can be used to study amino acid utilization in the pituitary.

Adult↗
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↗