Biomedical subjects

H Christensen

Publications and source records attributed to H Christensen.

At least 19 recordsLinked to original sources

PubMed2006

Geno- and phenotypic diversity of avian isolates of Streptococcus gallolyticus subsp. gallolyticus (Streptococcus bovis) and associated diagnostic problems.

Recently, strains of Streptococcus bovis were reclassified as Streptococcus gallolyticus. In the present study we describe for the first time an outbreak of S. gallolyticus in a broiler flock. Mortality during the first week was normal (<1%), with a final total mortality at the end of production reaching 4.3%. Specific symptoms were not observed. Postmortem pathology demonstrated enlarged and light spleens and livers accompanied by multifocal irregular necroses surrounded by a hemorrhagic zone. In addition, these birds suffered from arthritis and osteomyelitis. Strains isolated from liver and spleen lesions showed clonality as demonstrated by pulsed-field gel electrophoresis. Compared to strains representing previously derived phylogeny, including the S. bovis-S. equinus complex, the 16S rRNA-derived phylogeny of the strains investigated in this study demonstrated a paraphyletic group (S. gallolyticus) well separated from two monophyletic groups: (i) S. equinus-S. bovis plus S. infantarius and (ii) S. alactolyticus plus S. intestinalis. According to information in GenBank, none of the strains included from the two monophyletic groups have been isolated from birds. Further biochemical analyses, including tannase activity, identified for the first time avian isolates belonging to S. gallolyticus subsp. gallolyticus. However, these investigations also demonstrated a clear heterogeneity with pigeon isolates.

Animals↗

PubMed2006

Online randomized controlled trial of brief and full cognitive behaviour therapy for depression.

BACKGROUND: Effective internet-based programs for depression usually incorporate a component that provides telephone or email contact. Open access websites, without such contact, show high rates of attrition and poorer outcomes. The present study was designed as an exploratory investigation of the parameters that influence the effectiveness and retention of users on open access websites. We investigated whether brief cognitive behaviour therapy (CBT) was as effective as an extended version, whether add-on components of behaviour therapy or stress management contributed to positive outcomes, and whether longer programs were associated with greater attrition. METHOD: An online randomized controlled trial (RCT) was conducted between 13 January 2005 and 26 May 2005 (19 weeks). A total of 2794 registrants (1846 women and 948 men; median age category 35-44 years) with elevated scores on the Goldberg Depression Scale of 5.96 (S.D.=2.09) elected online to be randomized to one of six versions of a CBT website. The versions were compiled consisting of various components of brief CBT, extended CBT, behaviour strategies, stress management and problem solving. RESULTS: A total of 20.4% of participants completed the assigned intervention. The interaction of measurement occasion and treatment version was significant [F(13,131)=2.20, p=0.01]. A single module of brief introductory CBT was not effective in reducing depression symptoms. However, extended CBT with or without the addition of behaviour strategies resulted in the reduction of depression. CONCLUSIONS: Brief CBT-based interventions are not as effective as extended interventions. However, longer programs are associated with higher rates of dropout.

Adult↗

PubMed2006

Host-specific bacterial lineages in the taxon 2 and 3 complex of Pasteurellaceae.

The aim of the investigation was to determine the genetic relationship of a phenotypically diverse strain collection of epidemiologically unrelated strains from the taxon 2 and 3 complex of Bisgaard isolated from different hosts. A total of 325 isolates belonging to the taxon 2 and 3 complex of Bisgaard was characterized phenotypically in 82 characters. The genetic relationship among a subset of 60 isolates was investigated by amplified fragment length polymorphism (AFLP). The isolates were selected aiming at including the broadest diversity with regards to phenotype and host spectrum. The results suggested a statistically clear association between AFLP clusters and the host species families Columbidae (pigeon, dove), Anatidae (duck, goose) and Psittacidae (parrot, parakeet, budgerigar), respectively. This association was further supported by results from previous whole cell protein profiling and DNA:DNA hybridization studies. In conclusion, it appears that distinct genetic lineages within the taxon 2 and 3 complex of Bisgaard have evolved specificity for host bird species of different families. The observed host specificity of taxon 2 and 3 organisms may be used in future diagnostics and studies elucidating aspects of pathogenicity and epidemiology associated with the different lineages and their respective hosts.

Adaptation, Biological↗

PubMed2006

A preliminary study of the role of ducks in the transmission of Newcastle disease virus to in-contact rural free-range chickens.

The role of ducks in the transmission of Newcastle disease virus (NDV) to free-range village chicken was investigated experimentally. Newcastle disease (ND) seronegative ducklings reared in a pen were infected oronasally with velogenic NDV of intracerebral pathogenicity index (ICPI) 1.8 isolated from outbreaks in village chickens in Uganda. A first group of 3-week-old ND seronegative chicks was mixed with the ducks and they were kept together for 7 days. Both ducks and chicks were observed for ND clinical signs and any mortality, and they were bled and their sera were tested for ND antibodies by haemagglutination inhibition (HI) test. The chicks were removed, euthanized and examined for any ND lesions, while the ducks were transferred to a fresh pen and a second group of chicks was introduced and observed and treated as above. The ducks and the chicks tested positive for ND antibodies 7 days post infection and contact, respectively, but showed no clinical signs, post-mortem lesions or mortality. The mean ND antibody titre of the second group of chicks was lower than for the first group. This study has shown that although ducks can be infected with velogenic NDV, they do not show clinical signs but are able to transmit NDV to in-contact chicks. Further investigations are needed of the lack of clinical signs in the in-contact chicks and how long the ducks remain infective.

Animals↗

PubMed2006

Changing epidemiology of bacterial meningitis among adults in England and Wales 1991-2002.

We examined the epidemiology of community-acquired bacterial meningitis among adults in England and Wales between 1991 and 2002. Among 3169 cases, meningococcal infection was predominant among young adults and pneumococcal meningitis among older adults. Whilst infection due to most causes decreased, the incidence of tuberculous (TB) meningitis doubled over the 12 years. The mortality rate among meningococcal and pneumococcal infections fell from 0.45/10(5) to 0.31/10(5) (P=0.0001). This study demonstrates important changes in the epidemiology of bacterial meningitis among UK adults. Improvements in clinical management, childhood vaccination programmes and the re-emergence of tuberculosis are likely to be drivers of these changes.

Adolescent↗

PubMed2006

[Pasteurella] caballi infection not limited to horses - a closer look at taxon 42 of Bisgaard.

AIM: To investigate if taxon 42 of Bisgaard isolated from pigs represents genuine [Pasteurella] caballi, which was previously only isolated from horses. METHODS AND RESULTS: A total of 15 field isolates from horses and pigs from five different countries representing three continents were subjected to extended phenotypical characterization. Although minor differences were observed between taxon 42 and [P.] caballi, these differences did not allow phenotypic separation. Ribotyping based on HindIII digestion showed five profiles based on nine band positions. One [P.] caballi strain and two taxon 42 strains shared the same profile. Ribotyping using HpaII gave a higher diversity with nine profiles based on ten band positions. While no profiles were shared between the taxon 42 and [P.] caballi strains, pattern analysis showed that two of the taxon 42 isolates were most similar (91% similarity) with a [P.] caballi isolate. The 16S rRNA gene sequencing of one strain of taxon 42 and one strain of [P.] caballi was performed and compared with the published sequence for the type strain of [P.] caballi. The three strains showed nearly identical sequences with at least 99.8% similarity. DNA re-associations measured by the micro-well method were 79 and 77%, respectively between the type strain of [P.] caballi and two strains of taxon 42 representing distinct ribotypes and confirmed that taxon 42 belongs to [P.] caballi. CONCLUSION: The present investigation documents that [P.] caballi can be isolated from clinical respiratory specimens from pigs and the recognized association with respiratory infections in horses and horse bite infection in humans. Strains classified as taxon 42 are [P.] caballi isolated from pigs and for both pigs and horses, lesions mainly include the respiratory tract. SIGNIFICANCE AND IMPACT OF THE STUDY: The results will improve the diagnostics and progress studies of virulence and epidemiology of [P.] caballi.

Animals↗

PubMed2006

Pulmonary function, cognitive impairment and brain atrophy in a middle-aged community sample.

OBJECTIVE: To determine the relationship of lung function to brain anatomical parameters and cognitive function and to examine the mediating factors for any relationships. METHODS: A random sub-sample of 469 persons (men = 252) aged 60-64 years from a larger community sample underwent brain magnetic resonance imaging scans and pulmonary function tests (forced vital capacity, FVC, forced expiratory volume in the first second, FEV(1)). Subjects were assessed for global cognitive function, episodic memory, working memory, information processing speed, fine motor dexterity and grip strength. The magnetic resonance imaging scans were analysed for overall brain atrophy, subcortical atrophy (ventricle-to-brain ratio, VBR), hippocampal volume, and white matter hyperintensity (WMH) volume. RESULTS: FEV(1) had a significant negative correlation with overall brain atrophy and VBR in men. The FEV(1)/FVC ratio had a significant correlation with WMHs in both men and women. In regression models that controlled for sex, age, height, level of activity, smoking, chronic respiratory disease and education, FEV(1) and FVC were significant predictors of VBR but no other structural brain measure. Pulmonary function was also significantly related to information processing speed and fine motor dexterity. Male subjects with chronic respiratory disease had more deep WMHs. Path analyses to examine if structural measures mediated between lung function and cognition, and whether markers of inflammation and oxidative stress or cortisol mediated between lung function and brain measures were negative. CONCLUSIONS: Decreased lung function is related to poorer cognitive function and increased subcortical atrophy in mid-adult life. Presence of chronic respiratory disease may be related to deep WMHs in men.

Atrophy↗

PubMed2006

Growth hormone is a stimulating but not an essential factor in healing of colon. A study in GH-deficient dwarf rats.

BACKGROUND: Growth hormone (GH) has been implicated as an important factor in the healing and previous studies showed significant strength acceleration of experimental intestinal anastomoses. AIM: To study the healing of experimental colonic anastomoses in GH-deficient rats and to study the potential physiological effects of GH-substitution on healing parameters. CONCLUSION: Exogenous rhGH treatment started 7 days prior to surgery and continued until day 4 postoperatively accelerates the strength development of the experimental colonic anastomoses in dwarf rats indicating a potent role of growth hormone in colonic healing. However, GH is not essential in the healing process, since anastomotic healing in GH-deficient dwarf rats is like rats with normal pituitary function.

Anastomosis, Surgical↗

PubMed2006

A systematic review of telephone-based interventions for mental disorders.

To assess the effectiveness of telephone-based interventions for mental illness, a systematic search of the literature was conducted using the databases PsycINFO and PubMed, and the search engine Google Scholar. The search identified 14 studies evaluating telephone-based interventions in the areas of depression (n = 6), anxiety (n = 3), eating disorders (n = 3), substance use (n = 1) and schizophrenia (n = 1). Although these studies provide evidence that telephone interventions can be effective, the few studies conducted, small sample sizes and lack of randomized controlled trial methodology prevent firm conclusions from being drawn. The articles reviewed suggest that an effective telephone intervention includes clearly structured therapy sessions and homework tasks. However, further evidence using large-scale, randomized controlled trials must be obtained in order to inform government and telephone counselling agencies about the efficacy of telephone interventions.

Anxiety Disorders↗

PubMed2006

Separate and simultaneous enzymatic hydrolysis and fermentation of wheat hemicellulose with recombinant xylose utilizing Saccharomyces cerevisiae.

Fermentations with three different xylose-utilizing recombinant Saccharomyces cerevisiae strains (F12, CR4, and CB4) were performed using two different wheat hemicellulose substrates, unfermented starch free fibers, and an industrial ethanol fermentation residue, vinasse. With CR4 and F12, the maximum ethanol concentrations obtained were 4.3 and 4 g/L, respectively, but F12 converted xylose 15% faster than CR4 during the first 24 h. The comparison of separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) with F12 showed that the highest, maximum ethanol concentrations were obtained with SSF In general, the volumetric ethanol productivity was initially, highest in the SHF, but the overall volumetric ethanol productivity ended up being maximal in the SSF, at 0.013 and 0.010 g/Lh, with starch free fibers and vinasse, respectively.

Catalase↗

PubMed2006

Outbreak of E. coli O157 infection in the south west of the UK: risks from streams crossing seaside beaches.

In August 2004 seven cases of Escherichia coli O157 infection were identified in children on holiday in Cornwall, southwest England, all of whom had stayed at different sites in the area. Isolates from all seven cases were confirmed as E. coli serogroup O157 phage type 21/28. We carried out a case-control study among holidaymakers who visited the beach. A standardised questionnaire was administered by telephone to parents. They were asked where on the beach the children had played, whether they had had contact with the stream that flowed across the beach, and about their use of food outlets and sources of food eaten. Cases were more likely to have played in the stream than controls (OR [1.72- undefined]). The time spent in the stream by cases was twice spent there by controls. Cases and controls were equally exposed to other suspected risk factors. PFGE profiles for all the cases were indistinguishable. Increased numbers of coliforms were found in the stream prior to the outbreak. Cattle were found grazing upstream. We suggest that the vehicle of infection for an outbreak of acute gastrointestinal illness caused by E. coli O157 was a contaminated freshwater stream flowing across a seaside beach. The onset dates were consistent with a point source. Heavy rainfall in the days preceding the outbreak might have lead to faeces from the cattle potentially contaminated by E. coli O157 contaminating the stream, thereby leading to the outbreak. Control measures included fencing off the part of the stream in which children played, and putting up warning signs around the beach.

Bathing Beaches↗

PubMed2006

Case-control study for risk factors for Q fever in southwest England and Northern Ireland.

Q fever (Coxiella burnetti) is thought to account for 1% (700 cases) of community acquired pneumonia in the United Kingdom each year, and can result in serious complications such as endocarditis. Although outbreaks have frequently been reported worldwide, the causes are often not clearly identified and there have been few studies of risk factors in sporadic cases. We conducted a matched case-control study. Cases of acute Q fever in people aged over 15 years in southwest England and Northern Ireland were identified from January 2002 to December 2004. Controls were matched for age, sex and the general practice at which they were registered. Questionnaires asking about contact with animals, and leisure and work activities, were posted to cases and controls. Questionnaires were completed by 39/50 (78%) of the cases and 90/180 (50%) of the controls. In the single variable analysis, occupational exposure to animals or animal products was the only risk factor associated with cases at the 5% level (P=0.05, odds ratio (OR) 3.4). Long term illness appeared to be significantly protective (P=0.03, OR 0.3). In multivariable analysis the strength of association between occupational exposure and illness remained high (OR 3.6, 95% confidence interval (CI) 0.9 to 14.8) and smoking emerged as a possible risk factor. This is the first case-control study to identify occupational exposure to animals or animal products as the most likely route of infection in sporadic cases as opposed to outbreaks.

Adult↗

PubMed2005

Neuromuscular assessment in elderly workers with and without work related shoulder/neck trouble: the NEW-study design and physiological findings.

Musculoskeletal disorders in the neck and shoulder area are a major occupational concern in the European countries especially among elderly females. The aim was to assess these disorders based on quantitative EMG indicators and functional tests. 252 female computer users (45-68 years) were recruited from four European countries in two contrast groups: (1) 88 neck/shoulder (NS) cases reporting trouble in the neck and/or shoulder region for more than 30 days during the last year, and (2) 164 NS-controls reporting such trouble for no more than 7 days. Questionnaires, functional/clinical tests, and physiological recordings were performed in workplace related field studies. The results showed no differences in anthropometrics but NS-cases reported more strained head positions and more eye problems than controls. The psychosocial working factors were similar, although, NS-controls had slightly better scores on working conditions, general health, and vitality compared to cases. The NS-cases had lower maximal voluntary contraction (MVC) during shoulder elevation (mean (SD) 310 (122) N) compared to the controls (364 (122) N). During 30% MVC electromyography (EMGrms) in the trapezius muscle was lower in NS-cases (194 (105) muV) than in controls (256 (169) muV), while no differences were found regarding endurance time. Estimated conduction velocity was not different between NS-cases and -controls. Four functional computer tests were performed equally well by NS-cases and -controls, and the corresponding EMG variables also did not differ. A major finding in this large-scale epidemiological study is the significantly lower MVC in NS-cases compared with NS-controls together with lower EMGrms value at 30% MVC, while computer tasks were performed at similar relative muscle activation. The study was unable to reveal quantitative EMG indicators and functional tests that could objectively assess disorders in NS-cases.

Adult↗

PubMed2005

Determination of atorvastatin and metabolites in human plasma with solid-phase extraction followed by LC-tandem MS.

The aim of the present study was to develop a chromatographic method for the analysis of atorvastatin, o- and p-hydroxyatorvastatin (acid and lactone forms) in human plasma after administration of atorvastatin at the lowest registered dose (10 mg) in clinical studies. Sample preparation was performed by solid-phase extraction and was followed by separation of the analytes on an HPLC system with a linear gradient and a mobile phase consisting of acetonitrile, water and formic acid. Detection was achieved by tandem mass spectrometry operated in the electrospray positive ion mode. Validation of the method for the compounds for which reference compounds were available (acid forms of atorvastatin, o- and p-hydroxyatorvastatin) showed linearity within the concentration range (0.2-30 ng/ml for atorvastatin acid and p-hydroxyatorvastatin acid, and 0.5-30 ng/ml for o-hydroxyatorvastatin acid) (r2 > or = 0.99, n = 5 for all analytes). Accuracy and precision (evaluated at 0.5, 3 and 30 ng/ml for atorvastatin, p-hydroxyatorvastatin and 1, 3 and 30 ng/ml for o-hydroxyatorvastatin) were both satisfactory. The detection limit was 0.06 ng/ml for atorvastatin and p-hydroxyatorvastatin, and 0.15 ng/ml for o-hydroxyatorvastatin. The method has been successfully applied in a clinical study where atorvastatin, o- and p-hydroxyatorvastatin (both acid and lactone forms) could be detected in a 24-h sampling interval after administration of the lowest registered dose of atorvastatin (10 mg) for one week.

Atorvastatin↗

PubMed2005

Influence of age and carriage status on salivary IgA to Neisseria meningitidis.

Asymptomatic carriage of Neisseria meningitidis is common (5-35% of individuals) while the incidence of invasive meningococcal disease is fairly low (<1-5 per 100,000 per annum in Europe). Naturally acquired protective immunity may account for this difference. In this study, we investigated the relationship between anti-meningococcal salivary IgA and age and carriage. We showed that salivary IgA to a range of meningococcal antigens increased successively with age with some specificity for commonly circulating serosubtypes. In a group of 258 students 37 (14%) of whom were carriers of N. meningitidis serogroup B, higher levels of specific IgA were associated with carriage. Stratified analysis revealed a positive relationship between smoking and specific anti- N. meningitidis IgA independent of current carriage, weighted odds ratio (OR) 4.1 (95% CI 1.1-18) and OR 3.8 (95% CI 0.96-16) for reference strains B:1:P1.14 and B:4:P1.5,4 respectively. These data implicate IgA as a factor in host defence from meningococcal invasion, although the precise mechanisms remain uncertain.

Adolescent↗

PubMed2005

Comparison of the electromyographic activity in the upper trapezius and biceps brachii muscle in subjects with muscular disorders: a pilot study.

The aim of the present study was to investigate the extent to which work-related muscular disorders of the upper trapezius affect the activity of other pain-free muscles, in particular in the biceps brachii. Two groups of female subjects (age >43 years) participated in the study: seven affected subjects with self-reported disorders in the shoulder/neck region (cases) and nine healthy subjects (control group). Multi-channel electromyography (EMG) and force were recorded during maximum voluntary contractions (MVC) and during 6 min sustained contractions (at 30% MVC) of the upper trapezius and biceps brachii on the dominant side. From the EMG signals, the root mean square (RMS), median frequency (MDF) and single motor unit (MU) conduction velocity (CV) were estimated. From the force signal, the coefficient of variation was calculated. All data are presented as mean values and standard deviation. Differences between the cases and controls were found in the MVC force of the upper trapezius, which was lower in cases [253 (70) N] than in controls [357 (75) N], while the coefficient of variation of force during the sustained contraction was increased [cases 5.5 (2.2); controls 4.1 (1.9)]. The RMS (normalized to the RMS at MVC) during the 6 min sustained contractions was significantly lower in the cases than in the controls for both the upper trapezius and the biceps brachii. A tendency towards a smaller increase in the RMS with fatigue was only found in the trapezius muscle [slope: cases 6.5 (14.1) %/min, controls 10.2 (12.9) %/min]. No differences were found between the two subject groups with respect to the MDF and single MU CV in both muscles. While the lower RMS for the trapezius muscles of the cases may reflect changes at the local level, as well as in motor control, the lower biceps activity indicates a change in the central control strategies of the primarily unaffected muscle. Indications for a changed fatigability of the muscle were only found in the trapezius.

Case-Control Studies↗

PubMed2005

Activity patterns of wrist extensor muscles during wrist extensions and deviations.

Wrist extensor muscles are prone to certain focal musculoskeletal disorders for which the activation pattern of the extensor carpi radialis (ECR) and ulnaris (ECU) muscles may be important risk factors. Surface and intramuscular EMG of these muscles were recorded during isometric low-force wrist extension in semipronation and pronation as well as for ulnar/radial deviation, and were analyzed using root mean square (RMS) and decomposition methods. Despite shorter ECR length at semipronation, higher amplitudes of intramuscular EMG and of motor unit action potentials (MUAPs) were found in pronation than in semipronation. However, these changes were not detectable in the surface EMG. Higher ECR activity levels were also found during wrist extension compared to ulnar/radial deviation, and differences in the motor unit (MU) properties were found during ulnar deviation compared to radial deviation and extension. Remarkably, the MUAPs of ECR were almost twice as large as those of the ECU. Overall, the ECR muscle did not respond as predicted from biomechanical considerations, and in general activity level was higher than expected. This may partly explain why the tendon of the ECR often is associated with lateral epicondylitis.

Adult↗

PubMed2005

Age group differences in psychological distress: the role of psychosocial risk factors that vary with age.

BACKGROUND: There is continuing controversy about how age affects depression and anxiety, with a lack of consistent results across studies. Two reasons for this inconsistency are age bias in measures and different patterns of exposure to risk factors across age groups in various studies. METHOD: Data on anxiety and depression symptoms were collected in a community survey of 7485 persons aged 20-24, 40-44 or 60-64 years. These measures were investigated for factorial invariance across age groups. Data were also collected on a wide range of potential risk factors, including social, physical health and personal factors, with the aim of determining whether these factors might partly or wholly account for age group differences. RESULTS: The invariance of correlated latent factors representing anxiety and depression was examined across age groups, and a generalized measure of psychological distress was computed. Depression, anxiety and psychological distress showed a decline across age groups for females and a decline from 40-44 to 60-64 years for males. Some of these age differences were accounted for by other risk factors, with the most important being recent crises at work and negative social relationships with family and friends. CONCLUSION: Psychological distress generally declined across the age range 20-64 years and this was not attributable to measurement bias. Differential exposure to risk factors explained some, but not all, of the age group difference. Therefore other mechanisms that explain the lower level of distress in older age groups remain to be identified.

Adolescent↗