Biomedical subjects

B H Svensson

Publications and source records attributed to B H Svensson.

At least 19 recordsLinked to original sources

PubMed2006

Phthalate hydrolysis under landfill conditions.

Experimental data from a study using a landfill simulation reactor were used to develop and calibrate a one-dimensional distributed model of co-digestion of municipal solid waste and three phthalic acid diesters with different water solubilities. The three diesters were diethyl phthalate, dibutyl phthalate, and di-2-ethylhexyl phthalate. Two types of municipal solid wastes were assumed, easily degradable and recalcitrant. The model considered inhibition of hydrolysis of the recalcitrant fraction and phthalic acid esters, and also methanogenesis at acidic pH. The results indicated that the prolonged steady-state concentrations of the diesters in the leachates could be explained by equilibrium between physicochemical desorption and sorption processes for the three diesters. When methanogenic conditions were induced in the acidogenic landfill simulation reactor, inhibition of both hydrolysis of recalcitrant MSW and of phthalic acid esters ceased.

Hydrogen-Ion Concentration↗

PubMed2004

Methane emissions from a constructed wetland treating wastewater--seasonal and spatial distribution and dependence on edaphic factors.

Constructed wetlands for wastewater treatment have many advantages. They can be used for several purposes, for example, to reduce levels of organic matter and nutrients, and to retain toxic metals. However, most wetlands are inherently net sources of gaseous compounds like methane and nitrous oxide, which are of environmental concern due to their rapid current accumulation in the atmosphere and their potent global warming capacity. In order to determine the flux of methane from a constructed wetland a study was conducted over two growth seasons on a pilot scale wetland constructed to reduce nutrient levels in secondary treated wastewater. The emissions for the spring to autumn period averaged 141 mg CH(4)m(-2)d(-1) (S.D.=187), ranging from consumption of 375 mg CH(4)m(-2)d(-1) to emissions of 1739 mg CH(4)m(-2)d(-1). The spatial and temporal variations were large, but could be accounted for by measured environmental factors. Among these factors, sediment and water temperatures were significant in all cases and independent of the scale of analysis (r(2) up to 0.88).

Ecosystem↗

PubMed2003

Transformation of phthalates in young landfill cells.

Phthalic acid diesters are additives in a variety of materials that can end up in landfills. Leachates from a series of full-scale young landfill cells were analysed over time for dimethyl, diethyl, dibutyl, butylbenzyl, and di(2-ethylhexyl) phthalate (respectively designated DMP, DEP, DBP, BBP, and DEHP), and their corresponding monoesters monomethyl, monoethyl, monobutyl, monobenzyl, and mono(2-ethylhexyl) phthalate (MMP, MEP, MbutP, MbenzP, and MEHP, respectively), as well as o-phthalic acid (PA). One landfill cell was created in each of three consecutive years by deposition of the same type of waste in July and August. The pH, volatile fatty acids (VFAs), and total organic carbon (TOC) were measured to characterise development of the degradation phases in three landfill cells, which revealed early acidogenic to initial methanogenic stages. Analysis of the phthalate compounds showed that observed concentrations of the degradation products were below the detection limit in the acidogenic leachates but exceeded concentrations of their corresponding diesters in leachates from cells in the initial methanogenic phase. Maximum and average concentrations of phthalic acid were 50 and 23 mg/l, respectively, and the corresponding values for the other phthalates were 430 and 27 microg/l. The concentrations of all phthalates decreased during the establishment of stable methanogenic conditions.

Environmental Monitoring↗

PubMed2001

Measurements of methane emissions from landfills using a time correlation tracer method based on FTIR absorption spectroscopy.

Methane is an important climate gas contributing significantly to global warming. A large part of the anthropogenic emissions of methane comes from landfills. Due to the biogenic origin of these emissions and the inhomogeneous characteristics of landfills and their soil cover, these emissions show large spatial variation. Thus, development of reliable and cost-effective methods for measurements of these emissions is an important task and a challenge to the scientific community. Traditionally, field chamber methods have been used but also different area integrating methods based on downwind plume measurements. These measurements have been supported by meteorological data either directly from local measurements or by controlled release of tracer gas from the landfill providing the dispersion characteristics of the plume. In this paperwe describe a method,the Time Correlation Tracer method, combining controlled tracer gas release from the landfill with time-resolved concentration measurements downwind the landfill using FTIR absorption spectroscopy. The method has been tested and used on measurements at a landfill in southern Sweden over the past 1.5 years. The method has proven to be a usable method for measurements of total methane emission from landfills, and under favorable meteorological conditions we estimate an achievable accuracy of 15-30%. The real time analysis capability of the FTIR makes it possible to judge the success of the measurement already on site and to decide whether more measurements are necessary. The measurement strategy is relatively simple and straightforward, and one person can make a measurement from a medium sized landfill (1-4 ha) within a few days to a week depending on the meteorological situation.

Air Pollutants↗

PubMed1999

Degradation of phenol under meso- and thermophilic, anaerobic conditions.

Based on the results of preliminary studies on phenol degradation under mesophilic conditions with a mixed methanogenic culture, we proposed a degradation pathway in which phenol is fermented to acetate: Part of the phenol is reductively transformed to benzoate while the rest is oxidised, forming acetate as end product. According to our calculations, this should result in three moles of phenol being converted to two moles of benzoate and three moles of acetate (3 phenol + 2 CO2 + 3 H2O --> 3 acetate + 2 benzoate): To assess the validity of our hypothesis concerning the metabolic pathway, we studied the transformation of phenol under mesophilic and thermophilic conditions in relation to the availability of hydrogen. Hence, methanogenic meso- and thermophilic cultures amended with phenol were run with or without an added over-pressure of hydrogen under methanogenic and non-methanogenic conditions. Bromoethanesulfonic acid (BES) was used to inhibit methanogenic activity. In the mesophilic treatments amended with only BES, about 70% of the carbon in the products found was benzoate. During the course of phenol transformation in these BES-amended cultures, the formation pattern of the degradation products changed: Initially nearly 90% of the carbon from phenol degradation was recovered as benzoate, whereas later in the incubation, in addition to benzoate formation, the aromatic nucleus degraded completely to acetate. Thus, the initial reduction of phenol to benzoate resulted in a lowering of H2 levels, giving rise to conditions allowing the degradation of phenol to acetate as the end product. Product formation in bottles amended with BES and phenol occurred in accordance with the hypothesised pathway; however, the overall results indicate that the degradation of phenol in this system is more complex. During phenol transformation under thermophilic conditions, no benzoate was observed and no phenol was transformed in the BES-amended cultures. This suggests that the sensitivity of phenol transformation to an elevated partial pressure of H2 is higher under thermophilic conditions than under mesophilic ones. The lack of benzoate formation could have been due to a high turnover of benzoate or to a difference in the phenol degradation pathway between the thermophilic and mesophilic cultures.

Journal Article↗

PubMed1996

[Microalbuminuria in rheumatoid arthritis].

To assess the prevalence of microalbuminuria in patients with rheumatoid arthritis and its correlation with disease activity and drug treatment, we studied 65 patients with rheumatoid arthritis and 51 sex and age matched control persons. Microalbuminuria was significantly increased in patients with rheumatoid arthritis (27.7%) as compared to 7.8% in the control group. Patients with microalbuminuria had a significantly greater median duration of disease (11.2 v 7.8 years; p < 0.001). We found a significant correlation to C-reactive protein as a marker for disease activity. Also, a significant association to treatment with gold and penicillamine was found. The measurement of microalbuminuria by immunochemical methods represents a simple and sensitive test to detect subclinical renal damage and may be a sensitive indicator of disease activity in patients with rheumatoid arthritis. We suggest its use in the monitoring of patients with rheumatoid arthritis to detect early subclinical renal dysfunction and drug induced renal damage.

Adult↗

PubMed1996

Anaerobic degradation of phthalic acid esters during digestion of municipal solid waste under landfilling conditions.

Anaerobic microorganisms in municipal solid waste samples from laboratory-scale landfill reactors and a pilot-plant biogas digestor were investigated with the aim of assessing their ability to transform four commercially used phthalic acid esters (PAEs) and phthalic acid (PA). The PAEs studied were diethyl phthalate (DEP), butylbenzyl phthalate (BBP), dibutyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP). No biological transformation of DEHP could be detected in any of the experiments. Together with waste samples from the simulated landfilling conditions, the PAEs (except DEHP) were hydrolytically transformed to their corresponding monoesters. These accumulated as end products, and in most cases they were not further degraded. During incubation with waste from the biogas digestor, the PAEs (except DEHP) were completely degraded to methane and carbon dioxide. The influence of the landfill development phase on the transformations was investigated utilizing PA and DEP as model substances. We found that during both the intense and stable methanogenic (but not the acidogenic) phases, the microorganisms in the samples had the potential to transform PA. A shorter lag phase was observed for the PA transformation in the samples from the stable methanogenic phase as compared with earlier phases. This indicates an increased capacity to degrade PA during the aging phases of the municipal solid waste in landfills. No enhancement of the DEP transformation could be observed as conditions in the methanogenic landfill model changed over a year's time. The results indicate that microorganisms developing in a methanogenic landfill environment have a substantially lower potential to degrade compared with those developing in a biogas reactor.

Anaerobiosis↗

PubMed1996

Anaerobic degradation of xenobiotics by organisms from municipal solid waste under landfilling conditions.

The potential for biological transformation of 23 xenobiotic compounds by microorganisms in municipal solid waste (MSW) samples from a laboratory scale landfill reactor was studied. In addition the influence of these xenobiotic compounds on methanogenesis was investigated. All R11, 1,1 dichloroethylene, 2,4,6 trichlorophenol, dimethyl phthalate, phenol, benzoate and phthalic acid added were completely transformed during the period of incubation ( > 100 days). Parts of the initially added perchloroethylene, trichloroethylene, R12, R114, diethyl phthalate, dibutyl phthalate and benzylbutyl phthalate were transformed. Methanogenesis from acetate was completely inhibited in the presence of 2,5 dichlorophenol, whereas 2,4,6 trichlorophenol and R11 showed an initial inhibition, whenafter methane formation recovered. No transformation or effect on the anaerobic microflora occurred for R13, R22, R114, 3 chlorobenzoate, 2,4,6 trichlorobenzoate, bis(2 ethyl)hexyl phthalate, diisodecyl phthalate and dinonyl phthalate. The results indicate a limited potential for degradation, of the compounds tested, by microorganisms developing in a methanogenic landfill environment as compared with other anaerobic habitats such as sewage digestor sludge and sediments.

Anaerobiosis↗

PubMed1996

Clostridium ultunense sp. nov., a mesophilic bacterium oxidizing acetate in syntrophic association with a hydrogenotrophic methanogenic bacterium.

A syntrophic acetate-oxidizing bacterium, strain BST (T = type strain), was isolated from a previously described mesophilic triculture that was able to syntrophically oxidize acetate and form methane in stoichiometric amounts. Strain BST was isolated with substrates typically utilized by homoacetogenic bacteria. Strain BST was a spore-forming, gram-positive, rod-shaped organism which utilized formate, glucose, ethylene glycol, cysteine, betaine, and pyruvate. Acetate and sometimes formate were the main fermentation products. Small amounts of alanine were also produced from glucose, betaine, and cysteine. Strain BST grew optimally at 37 degrees C and pH 7. The G+C content of the DNA of strain BST was 32 mol%. A 16S rRNA sequence analysis revealed that strain BST was a member of a new species of the genus Clostridium. We propose the name Clostridium ultunense for this organism; strain BS is the type strain of C. ultunense.

Acetates↗

PubMed1995

Alanine as an end product during fermentation of monosaccharides by Clostridium strain P2.

The thermophilic Clostridium P2 was isolated from a semi-continuously fed reactor with high ammonium concentration. This bacterium formed substantial amounts of L-alanine as a major fermentation product from glucose, fructose and mannose. Low amounts of acetate, butyrate, carbon dioxide and hydrogen were also formed. A high partial pressure of hydrogen inhibited the degradation of the monosaccharides, whereas hydrogen removal, in the form of methanogenesis was found to be stimulatory. However, the amount of alanine produced per mole of hexose degraded did not change. Hexose degradation and alanine production were favoured by high ammonium concentrations. Nuclear magnetic resonance spectroscopy studies provided strong evidence that an active Embden-Meyerhof-Parnas pathway existed and that alanine was produced via an amination of pyruvate.

Alanine↗

PubMed1995

Stimulation of conversion rates and bacterial activity in a silage-fed two-phase biogas process by initiating liquid recirculation.

The effects of liquid recirculation on a liquefaction-acidogenic reactor in an anaerobic two-phase digesting system operating with grass-clover silage was studied during 40 days after initiating recirculation of effluent from the methanogenic reactor to the liquefaction-acidogenic reactor. An increase in alkalinity and, thus, an increase in pH from 5.2 to 6.0 occurred in the liquefaction-acidogenic reactor. During the same period, a 10-fold increase (from 0.2 to 1.9 g.l-1.h-1) in the degradation rate of mannitol and an almost 9-fold increase in the activity of hydrogenotrophic methanogens was observed. The estimated number of these bacteria increased by one order of magnitude. The average degradation rate of lactate increased 3-fold, probably as a consequence of the more efficient hydrogen consumption by the hydrogenotrophic methanogens. An observed increase in net mineralization of organic nitrogen compounds was probably the main reason for an enhanced net production of organic acids (from 0.2 to 0.9 g.l-1.d-1). The liquefaction of cellulose and hemicellulose was low from the start of recirculation (3% and 20% reduction, respectively) and did not seem to be affected by the liquid recirculation. This was in accordance with the low number of cellulose degraders (4.0 x 10(2) counts.ml-1) observed. The results from this investigation show that the initiation of liquid recirculation in silage-fed two-phase biogas processes will stimulate the activity of hydrogenotrophic methanogens in the liquefaction-acidogenic reactor. This will lead to more thermodynamically favourable conditions for acidification reactions which are dependent upon interspecies transfer of reducing equivalents.

Biodegradation, Environmental↗

PubMed1993

[Effect of pneumatic compression in connection with ergotherapeutic treatment of Colles' fracture. A clinical controlled trial].

We followed forty women with functional deficits in the wrist and hand after sustaining a Colles' fracture. The women participated in occupational therapy three times a week for three weeks. At the initial evaluation, after three weeks, and at a three month evaluation, we measured the following: range of joint movement, grip strength, hand volume (oedema), pain and ADL. There was significant improvement in most of the parameters measured after three weeks of occupational therapy, with a less significant improvement from three weeks to three months. Seventeen of the forty women received twenty minutes of intermittent pneumatic compression before occupational therapy. These patients showed significant improvement in wrist extension, compared with the control group of twenty-three patients. Occupational therapy is recommended for patients showing a functional deficit after Colles' fracture. Intermittent pneumatic compression is recommended as a supplement to occupational therapy.

Aged↗

PubMed1992

[Treatment of central facial nerve paralysis with electromyography biofeedback and taping of cheek. A controlled clinical trial].

We studied 35 patients with facial palsy after stroke, admitted to a rehabilitation hospital. We examined the patients on admission and after one, two and six months with 1) clinical evaluation of the facial function using a modified House-Brackmann scale, 2) photographs of patients with six different facial expressions; these photos were evaluated by "blinded" observers using the modified House-Brackmann scale, 3) questionnaire about patients emotional reactions to the facial paralysis and 4) facial sensation. No differences were found between a control group of 12 and a group of patients (23) training facial function 2-3 times a week, each session of 15 minutes, with EMG-biofeedback and cheek taped between training sessions. A significant improvement in facial function occurred spontaneously after one month in rehabilitation unit in the total group. After six months 2/3 of the patients had normal facial function or mild dysfunction. Patients with right-sided facial palsy showed a significantly better improvement at six months as compared to patients with left-sided facial palsy. The questionnaire showed that only half of the patients were aware of the asymmetric face. We cannot recommend training with EMG-biofeedback to patients with facial paralysis after stroke. Spontaneous remission is to be expected.

Bandages↗

PubMed1992

[Reflex dystrophy after reconstruction of the axillary artery].

Reflex sympathetic dystrophy (RSD) is a complex syndrome of pain, trophic changes and vasomotor instability affecting the limbs. Numerous theories have been suggested to explain the pathophysiology. None is universely accepted. In most of the patients reported, an antecedant event such as trauma or surgery is implicated in the initiation of symptoms. We describe a case of reflex sympathetic dystrophy developing after reconstruction of a. axillaris. To our knowledge there have only been a few previous descriptions of reflex dystrophy following vascular surgery. The mechanism of reflex sympathetic dystrophy secondary to vascular trauma is discussed. Presumely, damage to the arterial wall by trauma may initiate abnormal reflex activity and lead to RSD. We suggest that vascular surgery should be considered as a potential risk factor for the development of RSD.

Arterial Occlusive Diseases↗

PubMed1992

Low level laser therapy for myofascial pain in the neck and shoulder girdle. A double-blind, cross-over study.

In a controlled, cross-over study the effect of low level laser therapy (LLLT) was evaluated. During a five weeks period forty-seven female laboratory technicians received six laser and six placebo treatments to tender points in the neck and shoulder girdle. Subjects rated the placebo treatment significantly more beneficial than LLLT (p = .04). There was no reduction in consumption of analgesics associated with either laser or placebo treatment. The results indicate no beneficial effect of LLLT for myofascial pain.

Adolescent↗

PubMed1990

[Herpes zoster paresis. A review of the literature and case reports].

The incidence of paresis due to herpes zoster (HZ) infections are reported very differently in the literature with rates varying from 0.5 to 31%. Many of the paresis are presumed to be undiagnosed on account of topographic dissociation, variable periods from the cutaneous affection to the muscular involvement, masking of the paresis by pain, paresis of the intercostal and abdominal muscles which are not obvious and difficulties in correlating the visceral symptoms with a herpes zoster eruption. Paresis of the cranial nerves are easily diagnosed and 50% of all HZ paresis are diagnosed from this region. Early acyclovir treatment has improved the prognosis. Four cases of hypotonic herpes zoster paresis in immunocompetent persons are described and the diagnostic difficulties are discussed.

Acyclovir↗

PubMed1986

Life without oxygen: what can and what cannot?

The basic principles involved in the biotransformation of organic carbon compounds in the absence of molecular oxygen (dioxygen) are presented in this paper. The role of various electron acceptors during the breakdown of organic compounds is discussed and the metabolic end-products expected are summarized. The different biochemical possibilities and strategies for the anaerobic degradation of organic matter and the metabolic response of some organisms to anaerobiosis are elucidated. Positive and negative effects of anaerobiosis on environmentally relevant processes and their influence on man and on animals are reviewed. Finally, some examples of the biotechnological application of anaerobic processes are presented.

Anaerobiosis↗

PubMed1984

Different temperature optima for methane formation when enrichments from Acid peat are supplemented with acetate or hydrogen.

Laboratory studies of methane formation in peat samples from an acid subarctic mire in Sweden indicated the presence of a low-temperature-adapted methanogenic flora. Enrichment culture studies with ethanol, acetate, hydrogen, or a combination of these as substrate for methane formation provided evidence for the existence of two different methanogenic populations in the peat: one, unaffected by hydrogen and using acetate, with a temperature optimum at 20 degrees C; the other, oxidizing hydrogen, with a temperature optimum at ca. 28 degrees C.

Journal Article↗