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Biomedical subjects

S Larsson

Publications and source records attributed to S Larsson.

At least 73 records · Page 4Linked to original sources
PubMed2000

Energy saving electron pathways in proteins.

This paper is a contribution to the discussion of whether the general architecture of electron transfer sites in blue copper proteins is mainly a result of the structural preferences of the metal ion or is induced by the protein. Although the site is probably stable only when protected by the protein, there appears to be no strain from the latter on the structure in the vicinity of the copper atom. For an operative redox site it is further required that the geometry of the site is acceptable for both oxidation states, to avoid high reorganization energy. The site must also be connected to the outer world by suitable tunneling pathways. The blue copper sites appear to fulfill these requirements, but it is difficult to assess the role of evolutionary pressure to form electron transfer proteins in general.

Bacterial Proteins↗
PubMed2000

The aetiology and epidemiology of clavicular fractures. A prospective study during a two-year period in Uppsala, Sweden.

In a prospective study, the age- and gender-specific incidence and features of clavicular fractures were studied during 1989 and 1990. The population at risk consisted of about 200,000 individuals aged 15 or above in the county of Uppsala, Sweden. There were 187 clavicular fractures in 185 patients corresponding to an annual incidence of 50/100,000 (males 71/100,000, women 30/100,000). Males were significantly younger and sustained comminuted fractures more often than women. The fracture incidence decreased with age in both genders, although the reduction was significant only in men. Bicycle accidents most frequently caused clavicular fractures in both genders, whereas sports activities were significantly more common in men. Right and left clavicles were almost as frequently fractured, and a direct fall on the shoulder was the most frequent mechanism of injury for both genders. There was no difference between genders in the anatomical location with about three of four fractures occurring through the middle part and one of four through the acromial part of the clavicle. Ninety-five percent healed uneventfully, while non-union developed in 5% - evenly distributed between the middle part of the clavicle and the acromial part.

Accidents, Traffic↗
PubMed2000

Randomized clinical trial of laparoscopic versus open fundoplication: blind evaluation of recovery and discharge period.

BACKGROUND: There is a widespread belief that introduction of the laparoscopic technique in antireflux surgery has led to easier postoperative recovery. To test this hypothesis a prospective randomized clinical trial with blind evaluation was conducted between laparoscopic and open fundoplication. METHODS: Sixty patients with gastro-oesophageal reflux disease were randomized to open or laparoscopic 360 degrees fundoplication. The type of operation was unknown to the patient and the evaluating nurses after operation. RESULTS: The operating time was longer in the laparoscopy group, median 148 versus 109 min (P < 0.0001). The need for analgesics was less in the laparoscopically operated patients, 33.9 versus 67.5 mg morphine per total hospital stay (P < 0.001). There was no significant difference in postoperative nausea and vomiting. On the first day after operation patients in the laparoscopy group had better respiratory function: forced vital capacity 3.2 versus 2. 2 litres (P = 0.004) and forced expiratory volume 2.6 versus 2.0 litres (P = 0.008). Postoperative hospital stay was shorter in the laparoscopic group, median (range) 3 (2-6) versus 3 (2-10) days (P = 0.021). No difference was found in the duration of sick leave. CONCLUSION: Laparoscopic fundoplication was associated with a longer operating time, better respiratory function, less need for analgesics and a shorter hospital stay, while no reduction in the duration of postoperative sick leave was found compared with open surgery.

Adult↗
PubMed2000

Authors' reply

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Journal Article↗
PubMed2000

Lower airway bacterial colonization in asymptomatic smokers and smokers with chronic bronchitis and recurrent exacerbations.

Bacterial colonization of the lower airways in patients with chronic bronchitis (CB) has been described mainly in patients with co-existing chronic obstructive pulmonary disease (COPD). Although smoking has been identified as a risk factor for bacterial colonization it is not known whether asymptomatic smokers (AS) can be colonized. The aim of this study was to study lower airway bacterial colonization in smokers with stable CB and recurrent exacerbations and compare with AS and healthy never-smokers (NS). Thirty-nine smokers with CB and recurrent exacerbations (median FEV1 85% of predicted normal), 10 AS and 10 NS, underwent bronchoscopy and a two-step bronchoalveolar lavage (BAL) procedure where the first portion (20 ml, 'pre-BAL') was recovered separately from the rest (140 ml, 'BAL'). The degree of oropharyngeal contamination of pre-BAL and BAL samples was evaluated by cytology. Semiquantitative bacterial cultures were performed on all samples. Higher bacterial numbers than 10(3) colony-forming units (cfu) x ml(-1) in BAL were found only in the two smoking groups. Using 10(3) cfu x ml(-1) as cut-off, 6/10 (60%) in the AS-, and 7/35 (20%) in the CB-group were colonized in the lower airways. In all, 29% of all smokers had bacterial colonization. Only bacteria belonging to the normal oropharyngeal flora were found. The proportion of samples with oropharyngeal contamination was significantly lower in BAL than in pre-BAL (5% vs. 21%, P=0.039). The proportion of sterile samples was significantly higher in BAL than in pre-BAL (49% vs. 26%, P=0.002). Lower airway bacterial colonization was found both in asymptomatic smokers and in patients with CB. Colonization with potential respiratory pathogens is uncommon in patients with CB and recurrent exacerbations without severe airflow obstruction. The two-step BAL procedure seems to decrease oropharyngeal contamination.

Adult↗
PubMed2000

Management of extensive lesions of the aortic arch: review of 42 consecutive cases.

This retrospective study reviews the long-term results in aortic arch surgery. Forty-two consecutive patients (44-74 years) were operated on between 1980 and 1995. Nineteen patients had acute dissections of the aortic arch, 11 had chronic dissections and 12 had aneurysms. Twenty patients were given emergency surgery and 22 were operated on electively. Reconstruction of the aortic arch alone (31%) or with other aortic segments (69%) was performed during antegrade cerebral perfusion (81%) or circulatory arrest (17%). Sixteen patients died during the first 30 days (38%). Early mortality rates were 60% in emergencies and 18% in elective cases. Early mortality in the group with aneurysms was 33% and 40% in patients in the dissection group. Long-term follow-up to July 1998 is now complete. Twelve patients (28%) died during the follow-up period; 4 of these deaths were due to a rupture of the descending aorta. Three patients (11.5%) underwent late reoperations on the remaining aorta, without operative mortality. We recommend careful follow-up of patients with aortic arch disease and, when indicated, surgery to avoid the rupture of the remaining aorta.

Adult↗
PubMed2000

Gabapentin versus vigabatrin as first add-on for patients with partial seizures that failed to respond to monotherapy: a randomized, double-blind, dose titration study. GREAT Study Investigators Group. Gabapentin in Refractory Epilepsy Add-on Treatment.

PURPOSE: Our objective was to compare the efficacy and safety of gabapentin and vigabatrin as first-line add-on treatment in patients with partial epilepsy. METHODS: This was a multicenter, double-blind, randomized dose titration study. After baseline assessment and randomization, the dose could be increased if seizures persisted and reduced if side effects occurred. Health-related quality of life was assessed at baseline and at the end of the study. By a protocol amendment post hoc, all randomized patients were offered a standardized perimetry examination at the end of the study. Improvement rate was the proportion of patients with a reduction of seizure frequency of at least 50% during an 8-week period without any adverse events causing withdrawal. RESULTS: One hundred two patients were randomized and analyzed on an intent-to-treat basis. The improvement rate was 48% in the gabapentin group and 56% in the vigabatrin group. The improvement rate, when per protocol criteria were fulfilled, was 57% in the gabapentin group and 59% in the vigabatrin group. The proportion of seizure-free patients was 31% in the gabapentin group and 39% in the vigabatrin group. There was no difference in quality-of-life scores between the groups. Perimetry after termination of the study on 64 patients showed abnormal results in 3 of 32 patients in the vigabatrin group. CONCLUSION: Approximately one third of the patients in both groups became seizure-free. Although no major differences were seen in terms of the improvement rate between the groups, equivalence between the two drugs was not found.

Acetates↗
PubMed2000

Storage of platelets in additive solutions: effects of phosphate.

BACKGROUND AND OBJECTIVES: In a previous study, low adenine nucleotide levels and a reduced rate of glycolysis were found in platelet concentrates (PCs) prepared by apheresis and stored in a platelet additive solution (PAS). Our objective was to investigate whether the use of PAS with or without phosphate can influence platelet metabolism in a similar way. MATERIALS AND METHODS: The in vitro effects of storage in either plasma or a PAS (T-Sol or PAS-III, both containing citrate, acetate and sodium chloride, PAS-III containing also phosphate) of buffy-coat-derived pooled platelet concentrates (BC-PCs) and apheresis platelets were investigated. The use of PAS implies inclusion of some plasma (20 or 35%). Paired studies over 7 days included investigation of cell counts, pH, PO2, PCO2, bicarbonate, glucose, lactate, adenine nucleotides, and extracellular adenylate kinase activity as a marker for disintegration of platelets. The expected concentration of phosphate in T-Sol is 0.6-1.8 mmol/l (with CPD plasma) and 0.2-0.6 mmol/l (with ACD plasma), and in PAS-III, 15-25 mmol/l (calculated values). RESULTS: BC-PCs were compared during storage in 35% CPD plasma and 65% PAS (T-Sol or PAS-III) (experiment 1), or alternatively 20% CPD plasma and 80% PAS (T-Sol or PAS-III) (experiment 3). In both studies, PAS-III shows similar and significantly higher rates of glycolysis in terms of consumption of glucose (0.06 vs. 0.04 mmol/day/10(11) platelets) and production of lactate (0.11 vs. 0.07 mmol/day/10(11) platelets) compared with T-Sol. Levels of pH and adenine nucleotides were similar when 35% plasma was used. With only 20% plasma, significantly higher levels of adenine nucleotides were found with PAS-III compared to T-Sol. The storage of apheresis platelets in 35% ACD plasma and 65% PAS (either T-Sol or PAS-III) (experiment 5) gave significantly higher values for PAS-III compared to T-Sol with regard to consumption of glucose (0.08 vs. 0.06 mmol/day/10(11) platelets), production of lactate (0.14 vs. 0.11 mmol/day/10(11) platelets) and adenine nucleotide levels. CONCLUSION: With respect to apheresis PCs stored in media containing ACD plasma, our results suggest that the differences found are related to the concentration of phosphate. The results for BC-PCs stored in media containing CPD plasma suggest that PAS-III is preferable to T-Sol as the PAS at plasma concentrations below 35%. The mechanism behind the phenomena observed with BC-PCs is not known.

Blood Platelets↗
PubMed2000

Inhibitory effect of N-acetylcysteine on adherence of Streptococcus pneumoniae and Haemophilus influenzae to human oropharyngeal epithelial cells in vitro.

BACKGROUND: Bacterial adherence to mucosal and epithelial cell structures is of importance for the persistence of bacteria in the airways. Cigarette smoking and chronic bronchitis are associated with increased bacterial adherence. N-Acetylcysteine (NAC) medication reduces the number of infectious exacerbations in patients with chronic bronchitis, and NAC medication has been associated with low intrabronchial bacterial numbers. OBJECTIVE: We investigated whether NAC influences bacterial adherence as a possible mechanism behind its clinical effects. METHODS: Highly adhering test strains of Streptococcus pneumoniae and Haemophilus influenzae were used to investigate the influence of four pharmacological compounds on adherence to oropharyngeal epithelial cells in vitro. Adhesion assays were performed both during short-term exposure to, as well as after long-time incubation with, NAC, lidocaine, hydrocortisone and terbutaline at concentrations not inhibiting bacterial growth. RESULTS: Only NAC showed a significant inhibitory effect on adhesion of H. influenzae during short-term incubation. After long-term incubation, both NAC and hydrocortisone inhibited bacterial adhesion for both strains in a dose-dependent manner. When NAC's effect on three different strains of S. pneumoniae and four strains of H. influenzae was studied, inhibition of bacterial adhesion was found for three strains of each species. CONCLUSIONS: NAC lowers bacterial adhesion in vitro to oropharyngeal epithelial cells in doses equivalent to that is being used clinically. This effect might be a contributory mechanism behind the reduction of infectious exacerbations in chronic bronchitis patients.

Acetylcysteine↗
PubMed2000

Influence of lignocellulose-derived aromatic compounds on oxygen-limited growth and ethanolic fermentation by Saccharomyces cerevisiae.

Phenolic compounds released and generated during hydrolysis inhibit fermentation of lignocellulose hydrolysates to ethanol by Saccharomyces cerevisiae. A wide variety of aromatic compounds form from lignin, which is partially degraded during acid hydrolysis of the lignocellulosic raw material. Aromatic compounds may also form as a result of sugar degradation and are present in wood as extractives. The influence of hydroxy-methoxy-benzaldehydes, diphenols/quinones, and phenylpropane derivatives on S. cerevisiae cell growth and ethanol formation was assayed using a defined medium and oxygen-limited conditions. The inhibition effected by the hydroxy-methoxy-benzaldehydes was highly dependent on the positions of the substituents. A major difference in inhibition by the oxidized and reduced form of a diphenol/quinone was observed, the oxidized form being the more inhibitory. The phenylpropane derivatives were examined with respect to difference in toxicity depending on the oxidation-reduction state of the gamma-carbon, the presence and position of unsaturated bonds in the aliphatic side chain, and the number and identity of hydroxyl and methoxyl substituents. Transformations of aromatic compounds occurring during the fermentation included aldehyde reduction, quinone reduction, and double bond saturation. Aromatic alcohols were detected as products of reductions of the corresponding aldehydes, namely hydroxy-methoxy-benzaldehydes and coniferyl aldehyde. High molecular mass compounds and the corresponding diphenol were detected as products of quinone reduction. Together with coniferyl alcohol, dihydroconiferyl alcohol was identified as a major transformation product of coniferyl aldehyde.

Aerobiosis↗
PubMed2000

Introduction: community action research and the prevention of alcohol problems at the local level.

Many community action projects from around the world exist to reduce alcohol problems at the local level. The role of research within this international movement is discussed within this introduction for the entire special issue on community action research in alcohol problem prevention. Previous community prevention programs have utilized a variety of prevention strategies: (a) an educational approach which focuses on changing behavior through changes in knowledge, attitudes, and information; and (b) an environmental approach which focuses on changing behavior through changes in the social and economic systems within a community. Many projects have used both approaches. This special issue provides a current overview of many types of community action projects from different countries and summarizes what has been learned to date from these experiences.

Alcoholism↗
PubMed2000

To prevent alcohol problems in Europe by community actions--various national and regional contexts.

The European transformation during the 1990s, concerning political, economic, social and cultural changes, has made alcohol policy in many countries very fragile and uncertain because of new social and economic conditions and decreasing power of national governments. On this background, regions, municipalities, nongovernmental organizations and the civic society are to play a more prominent role in the European alcohol policy arena. In December 1997 the first European research and evaluation symposium on community action alcohol programs was held in Malmö, Sweden. The themes were: Research-based evaluation of community action programs; The interaction between local, national, and European prevention strategies; Local programs in schools, workplaces, health sectors, primary health care, and other community contexts; The role of citizens' movements, consumer organizations, women's groups, and other voluntary organizations; Local political action. This paper is the first attempt to summarize the similarities and differences in the programs presented at the symposium.

Alcohol Drinking↗
PubMed2000

Time trends in alcohol habits. Results from the Kirseberg project in Malmö, Sweden.

This paper reports on a pilot demonstration to implement an alcohol consumption reduction project in the community of Kirseberg, located in the city of Malmö, Sweden. The objective is to present data on time trends in alcohol use habits and alcohol-use-related problems in the Kirseberg population and to discuss potential effects of the alcohol prevention activities. It was possible to implement an alcohol consumption prevention community program successfully. The analysis of time trends in alcohol use habits and alcohol-use-related problems was, however, mainly inconclusive, but indicated a decrease in alcohol consumption and alcohol-use-related problems among young and middle-aged men.

Adult↗
PubMed2000

The effect of implant design and bone density on maximum torque and holding power for femoral neck fracture devices.

BACKGROUND AND AIMS: Displacement of internally fixed femoral neck fractures due to implant migration is a common problem. This in vitro study was performed to compare maximum torque and holding power for five different implants. MATERIAL AND METHODS: Synthetic porous material with low, medium or high density was used to simulate cancellous bone. The tested implants included three conventional screws (AO, Olmed, Hansson), one screw with threads and a barb (Hybrid), and a pin with a hook (LIH). RESULTS: The Hansson screw provided higher maximum torque in low and medium density blocks when compared with the other implants (p < 0.0001) followed by LIH, Hybrid, Olmed, and AO. For high-density blocks there was no significant difference between Hansson and Hybrid screws, both with significantly higher torque than the other implants. The maximal pullout in low-density blocks differed significantly between all five implants with the Hansson screw providing the highest holding power. For medium and high-density blocks the conventional screws had significantly higher pullout resistance compared with the Hybrid and LIH. CONCLUSION: The in vitro model used seemed to provide reproducible and clinically relevant results. There was a good correlation between material density and holding power for all implants. Screws inserted without predrilling provided higher maximal torque while maximal pull out load seemed less affected by predrilling being used or not.

Bone Density↗
PubMed1999

Telomere loss in peripheral blood mononuclear cells may be moderately accelerated during highly active antiretroviral therapy (HAART).

It has been speculated that infection with HIV-1 may lead to a significant increase in turnover, and subsequent exhaustion, of immune repopulation. Given that telomeric DNA is lost on mitotic replication, telomere lengths can be used as an indirect gauge of this rate. We have analyzed the mean telomere restriction fragment lengths in peripheral blood mononuclear cells (PBMC) from 31 patients with established, though mainly untreated, HIV infection and found them to be no different than those among healthy controls. Our results are in line with several findings in CD4+ cell fractions but contradict a previous report suggesting that telomere shortening contributes to immune failure. Interestingly, after approximately 2 years of subsequent aggressive antiretroviral treatment we found a telomere reduction corresponding to a loss of about 250 base pairs per year; this is roughly tenfold above that predicted from healthy individuals. This could partly result from nucleoside analogue inhibition of the natural telomere replacement enzyme, telomerase-a reverse transcriptase inducible in certain hematopoietic cells. However, this may also indicate accelerated cell replacement on initiation of optimal therapeutic regimes or result from changes in the composition of the PBMC pool. These results suggest careful monitoring of telomere lengths during long-term HAART.

Adult↗
PubMed1999

Dose-response resistance to HIV-1/MuLV pseudotype virus ex vivo in a hairpin ribozyme transgenic mouse model.

We have investigated the efficacy of a hairpin ribozyme targeting the 5' leader sequence of HIV-1 RNA in a transgenic model system. Primary spleen cells derived from transgenic or control mice were infected with HIV-1/MuLV pseudotype virus. A significantly reduced susceptibility to infection in ribozyme-expressing transgenic spleen cells (P = 0.01) was shown. Variation of transgene-expression levels between littermates revealed a dose response between ribozyme expression and viral resistance, with an estimated cut off value below 0.2 copies of hairpin ribozyme per cell. These findings open up possibilities for studies on ribozyme efficacy and anti-HIV-1 gene therapy.

Animals↗
PubMed1999

Arthroscopic lavage reduced the recurrence rate following primary anterior shoulder dislocation. A randomised multicentre study with 1-year follow-up.

Young individuals have a high recurrence rate following non-operative treatment of traumatic primary anterior shoulder dislocation. The present multicentre study was undertaken to find out whether the results could be improved by using arthroscopic lavage as treatment. Sixty patients aged 16-30 years, with traumatic primary anterior shoulder dislocation were randomised into two groups. One group was treated with arthroscopic lavage within 10 days, while the other group was treated non-operatively. Rehabilitation was otherwise identical. At 1-year follow-up, 4 of 30 patients (13%) in the lavage group had had redislocation compared with 13 of 30 (43%) in the group treated non-operatively (P = 0.01). The difference in recurrence rate was more pronounced in younger patients. The functional outcome according to the Rowe shoulder score was better in the lavage group (P = 0.003), as was the anterior stability according to the apprehension test (P = 0.008). We conclude that arthroscopic lavage reduced the recurrence rate and produced a better functional outcome at 1-year follow-up than the non-operative treatment in young individuals.

Absenteeism↗