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Biomedical subjects

G Bengtsson

Publications and source records attributed to G Bengtsson.

At least 19 recordsLinked to original sources
PubMed2003

Effects of carbon substrate enrichment and DOC concentration on biodegradation of PAHs in soil.

AIMS: Two common reasons to explain slow environmental biodegradation of polycyclic aromatic hydrocarbons (PAHs), namely lack of appropriate carbon sources for microbial growth and limited bioavailability of PAHs, were tested in a laboratory bioassay using a creosote-contaminated soil. METHODS AND RESULTS: The soil, containing a total of 8 mg g-1 of 16 PAHs, was sieved and incubated in bottles for 45 days. The first explanation was tested by enrichment with the analogue anthracene and the non-analogue myristic acid, and both failed to stimulate degradation of all PAHs except anthracene. The second explanation was tested by addition of different concentrations of dissolved organic carbon (DOC), with effects depending on the DOC concentration and the molecular size of the PAH. The degradation was enhanced from 10 to 35% for 12 PAHs when the soil was saturated. The degraded amounts of individual PAHs were proportional to their concentration in the soil. CONCLUSIONS: The slow in situ degradation of PAHs was enhanced by more than three times by adding water as a solvent. Addition of DOC facilitated the degradation of four- to six-ring PAHs. SIGNIFICANCE AND IMPACT OF STUDY: Bioremediation of PAH-contaminated sites may be facilitated by creating water-saturated conditions but retarded by addition of other carbon substrates, such as analogue compounds.

Biodegradation, Environmental↗
PubMed2002

Persistent toxic chemicals: more than Stockholm persistent organic pollutants.

Schafer and Kegley bring up the important issue of excessive chemicals exposure of children. However, they do not consider in depth the "cumulative and simultaneous exposures faced by children, (.) moving beyond the chemical-by-chemical approach of the past", as quoted from the US Environmental Protection Agency national agenda to protect children from environmental health threats. Existing evidence for contamination by many substances beyond those dealt with in the article calls for additional protective measures. These could include an extra margin of exposure by a factor of 10 to cover cumulation of chemicals, for adults and children alike.

Child↗
PubMed2001

Provitamins and vitamins D₂and D₃in Cladina spp. over a latitudinal gradient: possible correlation with UV levels.

Provitamin D2, vitamin D2 and vitamin D3 were identified in the thallus of a lichen species, Cladina arbuscula (Wallr.) Hale and W.L. Culb. The identification of vitamin D3 was supported by: (1) co-chromatography in both reverse and straight phase HPLC (high performance liquid chromatography), (2) ultraviolet absorption spectrum, and (3) molecular ion peaks demonstrated by ESI (electrospray ionisation) mass spectrometry. The contents of vitamin D3 range from 0.67 to 2.04 μg g⁻¹ dry matter in the thalli of C. arbuscula specimens grown under different natural conditions, while provitamin D3 could not be detected. The ranges for provitamin D2 and vitamin D2 were 89-146 and 0.22-0.55 μg g⁻¹ dry matter, respectively, while the contents of provitamin D3 were below the detection limit (0.01 microg g(-1) dry matter). When C. arbuscula thalli collected at different latitudes from northern Finland to Greece were compared, a positive correlation of vitamin D2 and D3 contents with modelled UV-B radiation at the collection sites was found. A single sample of C. rangiferina from northern Finland gave much higher values for the vitamins. A possible reason could be the lower content of UV-B absorbing pigment in the latter species.

Ascomycota↗
PubMed2001

Contribution of suspended and sorbed groundwater bacteria to degradation of dissolved and sorbed aniline.

The influence of sorption on the mineralisation of 50 pg aniline l(-1) was examined in an aquifer material under batch conditions. The study was designed to distinguish the rates and extent of biodegradation of the sorbed and the dissolved trace organic and the contribution of sorbed and suspended bacteria to the degradation. Four different mathematical models were developed with different assumptions about the partitioning of aniline degradation and bacterial activity between the solid and the aqueous phases. The models were developed by combining an expression for logistic growth of the degrading population with Michaelis-Menten kinetics for the transformation of aniline. It was tested by a series of laboratory experiments conducted with 14C-labelled aniline, aseptically treated aquifer sand and filter-sterilised groundwater in different proportions and bacteria isolated from pristine groundwater. Model evaluation of the experimental data suggested that the fate of aniline was mainly controlled by suspended bacteria degrading both the dissolved and sorbed fractions. The degradation was slow, with a first-order degradation rate equal to 10(-6) h(-1).

Aniline Compounds↗
PubMed2001

Post-deposition transport of radionuclides in fruit.

This paper considers two main pathways for contamination of fruit by radionuclides: (i) absorption after deposition directly to exposed fruit surfaces, and (ii) absorption after deposition to other exposed plant surfaces followed by translocation to fruit. The aim is to collect the available information on fruit from temperate regions, identify the factors affecting post deposition processes in fruit plant systems, identify gaps in knowledge and give recommendations for future work. The majority of information available on above-ground absorption and further translocation to fruit concerns 134Cs and 85Sr in soluble form in apple, strawberry and grapevine. In general, 85Sr is absorbed and translocated to a lesser extent than is 134Cs. The rate of absorption and translocation depends on the physiological stage and age of the plant, and varies between different plant species and varieties.

Absorption↗
PubMed2001

Degradation of dissolved and sorbed 2,4-dichlorophenol in soil columns by suspended and sorbed bacteria.

The influence of sorption of bacteria, as well as 2,4-dichlorophenol (2,4-DCP), on the mineralization of 100 microg l(-1) of the organic compound was examined in an aquifer material under advective flow conditions (column displacement technique). The study was designed to distinguish the rates and extent of biodegradation of the sorbed and the dissolved trace organic and the contribution of sorbed and suspended bacteria to the degradation. The degradation of dissolved 2,4-DCP was significantly faster than the degradation of the same compound sorbed to the solids, and suspended bacteria degraded the dissolved compound at a higher rate than sorbed bacteria, also on a per cell basis. The suspended bacteria degraded 8-12% of the added dissolved 2.4-DCP, while sorbed bacteria made a smaller contribution by degrading about 5% of sorbed 2,4-DCP. No degradation was seen with sorbed 2,4-DCP and suspended bacteria, and a marginal contribution was made by sorbed bacteria on the degradation of dissolved 2,4-DCP (<0.4%).

Bacteria↗
PubMed1995

Effects of hyperosmolar glucose, prostaglandin-F2 alpha and 15-methyl-prostaglandin-F2 alpha on human placental cells in vitro.

The objective of this study was to assess the ability of certain drugs, used for local injection therapy of ectopic pregnancy, to suppress the activities of cultured human placental cells. Placental cells from legal first trimester abortions were prepared by collagenase treatment and density gradient centrifugation. The cells were exposed to hyperosmolar glucose (500 mg/ml), 15-methyl-prostaglandin-F2 alpha (15-m-PGF2 alpha; 10(-7) to 10(-3) mol/l) and prostaglandin-F2 alpha (PGF2 alpha; 10(-5) to 5 x 10(-3) mol/l) for 30 min on days 2-4 after seeding. The effects on the secretion of human chorionic gonadotrophin (HCG) and progesterone, as well as on the protein content per culture well, were measured. Hyperosmolar glucose was the most effective drug and caused a marked decrease of the protein content in the culture wells and a reduction of progesterone secretion. Of the two prostaglandins, only 15-m-PGF2 alpha affected the viability of the cells and reduced the protein content of the wells. The clinical effectiveness of the two groups of drugs seems to be similar but certain in-vitro effects are different. Thus in vivo they may act on different target tissues. Against this background, the combination of hyperosmolar glucose and prostaglandins might be an interesting approach for local injection therapy for tubal pregnancy.

Carboprost↗
PubMed1993

What is a reasonable cost for protection against radiation and other risks?

In Sweden, the National Audit Bureau is encouraging attempts at discussing the costs of protection. For many years, a government authority considering new regulations must provide the government with background material illustrating the costs, the expected benefits, and other aspects of the decision. Direct costs should be stated together with nonquantifiable factors indicated by a valuation of whether their consequences are positive or negative. Applied to radiation protection, this includes discussion of the resources worth spending in order to prevent a case of serious radiation injury. If the marginal cost for a protective measure is < 5 million Swedish crowns (5 MSEK: approximately 1 million U.S. dollars) per prevented case, the radiation protection authority considers the measure to be strongly justified. If the cost exceeds 25 MSEK per case, then very strong reasons are required for implementation of the measure. In the intermediate interval, measures are particularly justified if the marginal costs are in the lower end and the total societal cost of the protection is of little concern at the national economical level. The interval 5-25 MSEK per case corresponds to 0.4-2 MSEK person-sievert-1. Resource allocation for health protection in general, ethical aspects, and practical difficulties in assessing costs and risks are briefly discussed in the paper. Priorities in Swedish radiation protection are presented and a case study for the use of carbon fiber cassettes in x-ray diagnostics is given as an example.

Cost-Benefit Analysis↗
PubMed1993

Biopotency of vitamin E in lucerne meal for chickens.

In order to estimate the biopotency of vitamin E in lucerne/alfalfa meal in comparison to that of dl-alpha-tocopheryl acetate (dl-alpha-Ta; all-rac-alpha-Ta) a study was conducted with newly hatched White Leghorn male chicks. An increase in the vitamin E level in the liver and plasma, and the prevention of nutritional encephalomalacia (NE) were used as criteria for biopotency. After a vitamin E depletion period of one week posthatching, the chicks continued on a semipurified, vitamin E free basal diet without vitamin E supplementation, or were repleted with graded levels of that vitamin for six weeks, provided as extracted lucerne oil or as dl-alpha-Ta. High performance liquid chromatography (HPLC) with fluorescence detection was used for the analysis of the vitamin E homologues. The diagnosis of NE was based on clinical and histopathological observations. A significant increase (P < 0.05) in vitamin E content in the liver and plasma was observed in response to dietary supplementation with both vitamin E sources. The linear increase both in the liver and plasma storage assays was associated with a reduced incidence of NE. The disease was totally prevented by a dietary supplement of 7.50 and 5.40 mg vitamin E/Kg feed provided as dl-alpha-Ta or lucerne oil, respectively. The natural biopotency of the vitamin E in lucerne meal compared with that of dl-alpha-Ta in the liver and plasma storage assays and in the prevention of NE was 123, 105 and 99%, respectively, as calculated by the slope ratio technique.

Animal Feed↗
PubMed1992

Low-dose oral methotrexate as second-line therapy for persistent trophoblast after conservative treatment of ectopic pregnancy.

The aim of this study was to evaluate the efficacy of methotrexate as second-line treatment for ectopic pregnancy. Oral methotrexate was used in 15 patients with evidence of persistent trophoblast after conservative laparoscopic surgery for tubal pregnancy. The treatment was successful in 14 of 15 cases, and the mean time for decline of serum hCG to nonpregnant levels was 24 days. In the remaining case, hCG continued to rise. Side effects were noticed, even at a low dosage, but only in those subjects not receiving citrovorum rescue. As an alternative to a second operation, oral methotrexate appears to be an effective and well-tolerated therapy for persistent trophoblast.

Chorionic Gonadotropin↗
PubMed1991

Introduction: present knowledge on the effects of radioactive contamination on pregnancy outcome.

This introduction gives a brief review of the effects on pregnancy outcome that might follow radioactive contamination of the environment. These include miscarriages, congenital anomalies, damage to the central nervous system expressed through reduced intelligence and a risk of tumours late in life. Knowledge is fragmentary and field studies are difficult, which lends weight to the attempts at studying the effects of the Chernobyl accident in Europe which are the subject of the present symposium.

Accidents↗
PubMed1989

Nitrate reduction in a groundwater microcosm determined by N gas chromatography-mass spectrometry.

Aerobic and anaerobic groundwater continuous-flow microcosms were designed to study nitrate reduction by the indigenous bacteria in intact saturated soil cores from a sandy aquifer with a concentration of 3.8 mg of NO(3)-N liter. Traces of NO(3) were added to filter-sterilized groundwater by using a Darcy flux of 4 cm day. Both assimilatory and dissimilatory reduction rates were estimated from analyses of N(2), N(2)O, NH(4), and N-labeled protein amino acids by capillary gas chromatography-mass spectrometry. N(2) and N(2)O were separated on a megabore fused-silica column and quantified by electron impact-selected ion monitoring. NO(3) and NH(4) were analyzed as pentafluorobenzoyl amides by multiple-ion monitoring and protein amino acids as their N-heptafluorobutyryl isobutyl ester derivatives by negative ion-chemical ionization. The numbers of bacteria and their [methyl-H]thymidine incorporation rates were simultaneously measured. Nitrate was completely reduced in the microcosms at a rate of about 250 ng g day. Of this nitrate, 80 to 90% was converted by aerobic denitrification to N(2), whereas only 35% was denitrified in the anaerobic microcosm, where more than 50% of NO(3) was reduced to NH(4). Assimilatory reduction was recorded only in the aerobic microcosm, where N appeared in alanine in the cells. The nitrate reduction rates estimated for the aquifer material were low in comparison with rates in eutrophic lakes and coastal sediments but sufficiently high to remove nitrate from an uncontaminated aquifer of the kind examined in less than 1 month.

Journal Article↗