Biomedical subjects

J Christensen

Publications and source records attributed to J Christensen.

At least 37 records · Page 2Linked to original sources

PubMed2001

Data-quality issues and alternative variable-screening methods in a questionnaire-based study on subclinical Salmonella enterica infection in Danish pig herds.

Our aim was to determine risk factors for subclinical Salmonella enterica infection in Danish finishing-pig herds. In this paper, the evaluation, combining and initial reduction of variables is presented, along with assessment of the hypotheses in the preliminary statistical testing. The first group of herds was selected at random with no former knowledge of S. enterica infection. Both the herd prevalence and the within-herd prevalence among these herds turned out to be low; hence, some additional herds were selected from The Danish Salmonella Control program, based on their high seroprevalence. This resulted in a hybrid case-"control" design of the study and therefore, five different methods of categorising the data were used to ensure that variables were not wrongfully excluded as a result of using an improper design. Our questionnaire focused on management, infection-limiting precautions and feed and feeding procedures. To establish the prevalence of S. enterica infection within herds at the time of the visit, 50 blood samples from each herd were collected and serologically examined. The reliability of each variable from the questionnaire was assessed and it was decided which variables should be selected, disregarded, combined with other variables and/or recoded. In the simple statistical testing (2x2 tables, cut-off: P=0.25) herds were defined as subclinically S. enterica infected if the within-herd proportion of individual pigs with OD%>10 was more than 20%. The results included questionnaires from 96 randomly selected and 39 high-seroprevalence herds and 6814 blood samples. The initial 95 variables originally included in the questionnaires were reduced to 21 by critical check, combination, recoding and preliminary screening. We failed to demonstrate "herd size" as a risk factor for subclinical S. enterica infection in pig herds.

Analysis of Variance↗

PubMed2001

Detection of monocyte/macrophage cell populations in effusions: a comparative study using flow cytometric immunophenotyping and immunocytochemistry.

The objective of the present study was to compare the efficiency of immunophenotyping using flow cytometry (FCM) and immunocytochemistry (ICC) in the detection of macrophages in serous effusions. Cytoblock sections from 90 effusions were stained for the monocyte/macrophage marker CD14, using ICC. Fresh-frozen samples of all cases were analyzed for CD14 expression, using FCM. Epithelial, lymphoid, and mesothelial cell populations were identified using antibodies against Ber-EP4, CD45, and N-cadherin, respectively. Results were compared with clinical parameters and morphological diagnosis. Thirty-nine specimens were cytologically diagnosed as malignant, containing tumor cells of nonhematologic origin, whereas 46 were interpreted as benign. Two additional specimens were diagnosed as indeterminate or suspicious for malignancy, and 3 specimens contained lymphoma cells. CD14-positive cells were detected in 85/90 (94%) of effusions using FCM, and in all 90 specimens using ICC. The percentage of CD14-positive cells was highly variable, but in some specimens was as high as 76% using FCM and 85% using ICC. A good association was observed between the two methods in the detection of CD14-positive cells (P < 0.001). The presence of macrophages in effusions showed an association with female gender, using both FCM (P = 0.002) and ICC (P = 0.011), but none with effusion site, patient age, clinical and cytological diagnosis, or presence of Ber-EP4-positive cells (P > 0.05). The presence of Ber-EP4-positive cells showed a strong association with the cytological diagnosis of malignancy (P < 0.001). In conclusion, macrophages are a significant cell population in effusions, of both benign and malignant etiology, due to both their size and their possible confusion with cancer cells. Both FCM and ICC aid in the recognition of these cells, and thus provide an effective tool for the identification of different cell populations in effusions.

Adult↗

PubMed2001

Novel PCR assay for differential detection and screening of erythrovirus B19 and erythrovirus V9.

Diagnosis of erythrovirus B19 relies on serology and the detection of viral DNA. These techniques were believed to detect all field isolates because erythrovirus B19 has been known to undergo little genetic variation (1-2%). Recently, a distinct erythrovirus isolate termed V9, markedly different from erythrovirus B19 (>11% nucleotide disparity), was isolated from a child in France suffering from transient aplastic anemia. Standard PCR assays and serological tests failed to demonstrate an acute erythrovirus B19 infection. Subsequent sequencing of the erythrovirus V9 genome shows that the nucleotide discrepancies encompass the entire genome, indicating that standard erythrovirus B19 PCR assays will not reliably detect erythrovirus V9 DNA. As a tool for studying the epidemiological role and medical importance of this erythrovirus variant, a PCR assay is described that allows simultaneous detection of, and distinction between, erythrovirus B19 and the V9 isolate. Examination of 100 erythrovirus B19 IgM positive samples as well as plasma pools representing 100,000 Danish blood donor units for the presence of B19 and V9 DNA was performed. Despite the apparent absence of erythrovirus V9 in the clinical samples at present, the DNA sequence variability demonstrates that the erythrovirus group may be more divergent than thought previously and the child harboring this isolate may herald erythrovirus V9 as a possible emerging virus.

Blood Donors↗

PubMed2001

On-pump versus off-pump coronary artery bypass: independent risk factors and off-pump graft patency.

OBJECTIVE: Current knowledge on off-pump coronary artery bypass (OPCAB) generally stems from single surgeons' experience or from series where OPCABs constituted a minor fraction of coronary operations. The present center decided to venture as far into OPCAB as possible during 1999. The present series thus represents the average surgeon's experience. METHODS: During 1999, 533 patients underwent coronary artery bypass grafting using cardiopulmonary bypass (CPB) in 368 and OPCAB in 165 including the circumflex artery (CX) area in 91. Coronary arteriography was performed before discharge in the first 103 OPCAB patients. RESULTS: The CPB and OPCAB groups differed as regards left ventricular ejection fraction (53+/-13 versus 57+/-11, P < 0.0001) and frequency of triple-vessel or left main stem disease (84 versus 32%, P < 0.0001) but were comparable as regards diabetes (12%), prior myocardial infarct (57%), unstable angina (21%), and previous heart surgery (3%). Using multivariate analyses, 30-day mortality (1.3%), P-creatine kinase myocardial band (CKMB) > 80 microg/l (11.1%), re-sternotomy for bleeding (4.5%) or dehiscense (1.7%), transitory cerebral ischemia and stroke (1.7%), supraventricular tachycardia (27.4%), and hospital stay (mean 8 days) were unrelated to off- versus on-pump surgery as well as to OPCAB in triple-vessel disease. CX branches < or = 1mm, > or = 5 distal anastomoses, prior heart surgery, right coronary artery (RCA) branches < or = 1.5mm, 8-21 days old myocardial infarct, female gender, and preoperative acute arrhythmia (among others) were identified as independent risk factors for mortality or increased CKMB in all 533 patients. The latter five risk factors were reproduced in the OPCAB group isolated. The patency in the 103 OPCABs was 95.3, 91.8, and 85.3% in the left anterior descending artery (LAD), CX, and RCA, respectively. Patency was inversely related to diameter of the grafted vessel in the LAD and CX areas, unlike the RCA area. CONCLUSIONS: The results after beating heart surgery were good also in patients with triple-vessel disease, but specific gains relative to on-pump surgery could not be shown. The independent risk factors in the OPCAB group may indicate relative contraindications for OPCAB grafting.

Adult↗

PubMed2001

Leishmanicidal, antiplasmodial, and cytotoxic activity of novel diterpenoid 1,2-quinones from Perovskia abrotanoides: new source of tanshinones.

Cryptotanshinone (1), a quinoid diterpene with a nor-abietane skeleton, and three new natural products, 1beta-hydroxycryptotanshinone (2), 1-oxocryptotanshinone (3), and 1-oxomiltirone (4), were isolated from roots of the Iranian medicinal plant Perovskia abrotanoides. Their structures were established using homo- and heteronuclear two-dimensional NMR experiments, supported by HRMS. The total amount of tanshinones isolated from dry roots of Perovskia abrotanoides was about 1.5%. The compounds exhibited leishmanicidal activity in vitro (IC(50) values in the range 18-47 microM). These findings provide a rationale for traditional use of the roots in Iran as a constituent of poultices for treatment of cutaneous leishmaniasis. The isolated tanshinones also inhibited growth of cultured malaria parasites (3D7 strain of Plasmodium falciparum), drug-sensitive KB-3-1 human carcinoma cell line, multidrug-resistant KB-V1 cell line, and human lymphocytes activated with phytohaemagglutinin A (IC(50) values in the range 5-45 microM). The toxicity of tanshinones toward the drug-sensitive KB-3-1 and the multidrug-resistant KB-V1 cells was the same, indicating that the compounds are not substrates for the P-glycoprotein drug efflux pump.

Abietanes↗

PubMed2001

Mitochondrial DNA depletion, near-fatal metabolic acidosis, and liver failure in an HIV-infected child treated with combination antiretroviral therapy.

A child with controlled human immunodeficiency virus infection presented with neurologic deterioration, lactic acidosis, and organic aciduria. Muscle biopsy revealed abnormal mitochondrial (mt) morphology, reduced mt enzyme activities, and mtDNA depletion. After adjustment of antiretroviral therapy to a regimen free of nucleoside analogs, marked improvement was seen in clinical status and mt abnormalities.

Acidosis↗

PubMed2001

The role of desmin and N-cadherin in effusion cytology: a comparative study using established markers of mesothelial and epithelial cells.

The objective of the present study was to analyze the role of the mesothelial markers desmin and N-cadherin in the diagnostic panel of serous effusions. A total of 181 pleural and peritoneal effusions consisted of 101 cases cytologically diagnosed as malignant (89 carcinomas, 12 mesotheliomas), 78 benign, and 2 inconclusive specimens. All specimens were immunostained using 11 antibodies, against epithelial membrane antigen, Ber-EP4, carcinoembryonic antigen, E-cadherin, CA 125, N-cadherin, desmin, calretinin, p53, vimentin, and CD45. After evaluation of immunocytochemistry results, 110 specimens were diagnosed as malignant (98 carcinomas, 12 mesotheliomas) and 71 as benign (56 cellular, 15 paucicellular). The presence of desmin was detected in benign mesothelial cells in 47 of 56 (84%) reactive cellular specimens compared with 1 of 12 (8%) malignant mesotheliomas and 2 of 98 (2%) carcinomas. N-cadherin was expressed in 48 of 56 (86%) reactive cases, 12 of 12 (100%) mesotheliomas, and 47 of 98 (48%) carcinomas. In carcinomas, N-cadherin expression was most often seen in ovarian carcinoma but was also found in other carcinomas. Calretinin, an established marker of mesothelial cells, was detected in 52 of 56 (93%) reactive specimens, 11 of 12 (93%) mesotheliomas, and 3 of 98 (3%) carcinomas. Evaluation of staining results led to reclassification of six malignant specimens as benign, whereas 17 cases diagnosed as benign and the two diagnosed as inconclusive were classified as malignant. In conclusion, desmin appears to be a promising marker for the distinction between reactive mesothelium and malignant epithelial cells in terms of both specificity and sensitivity, and its complementary use with calretinin is recommended. Unlike calretinin, it may also prove valuable for the distinction between benign and malignant mesothelial cells. N-cadherin does not have a role in the distinction between mesothelial and epithelial cells. However, it may prove useful in the characterization of carcinomas of unknown origin. As has previously been shown, a significant number of diagnoses that are based on morphologic examination alone are modified after the use of a broad antibody panel.

Adolescent↗

PubMed2001

Predictors of outcome in severely head-injured children.

OBJECTIVE: Determine variables in the acute care period associated with survival and pediatric intensive care unit (PICU) length of stay (LOS) for children with severe traumatic brain injury. DESIGN: Retrospective cohort. SETTING: Level 1 pediatric trauma center. PATIENTS: Children (0-17 yrs) admitted 1991 to 1995 with nonpenetrating traumatic brain injury and admission Glasgow Coma Scale score of or=14. Predictors of outcome were abstracted, including Pediatric Trauma Score, Glasgow Coma Scale score, Pediatric Risk of Mortality, physiologic variables, computed tomography evidence of brain injury, and neuroresuscitative medications. The fatality rate was 24%. Age and gender were similar between groups (p >or= .1). Survival was independently predicted by 6-hr Glasgow Coma Scale score (odds ratio [OR] 4.6; 95% confidence interval [CI] 2.06-11.9; p < .001) and maximum systolic blood pressure (OR 1.05; 95% CI 1.01-1.09; p < .02). Odds of survival increased 19-fold when maximum systolic blood pressure was >or=135 mm Hg (OR 18.8; 95% CI 2.0-178.0; p < .01). By discharge, 67% of patients had an age-appropriate Glasgow Coma Scale score. Median hospital costs were 8,798 dollars for survivors: only mannitol use independently predicted high cost (odds ratio 4.9; 95% CI 1.2-19.1; p < .01). For survivors, median PICU LOS was 2 days, although 25% had LOS >6 days. Six-hour Glasgow Coma Scale score (OR 0.62; 95% CI 0.48-0.80; p < .001) and mannitol (OR 7.9; 95% CI 2.3-27.3; p < .001) were each independently associated with a prolonged LOS among survivors. CONCLUSIONS: Patients with higher 6-hr Glasgow Coma Scale scores were more likely to survive. Adjusting for severity of injury, survival was associated with maximum systolic blood pressure >or=135 mm Hg, suggesting that supranormal blood pressures are associated with improved outcome. Mannitol administration was associated with prolonged LOS, yet conferred no survival advantage. We suggest reevaluation of blood pressure targets and mannitol use in children with severe traumatic brain injury.

Adolescent↗

PubMed2001

Removal of 10-hydroxycarbazepine by plasmapheresis.

Removal of the oxcarbazepine metabolite 10-hydroxycarbazepine (MHD) by plasmapheresis was evaluated during a series of six plasmaphereses of a 13-year-old boy with Rasmussen encephalitis. Plasmapheresis was performed after steady-state concentrations of MHD had been achieved with a dose of 2550 mg oxcarbazepine daily. The mean amount of MHD removed per plasmapheresis was 78.9 mg (SD: 6.0 mg), representing 3% to 4% of the daily oxcarbazepine dose and approximately 5% to 6% of body stores of MHD. The mean steady-state trough MHD concentration was 33.3 mg/L (SD: 1.8 mg/L), and this was remarkably stable during the entire plasmapheresis period. The serum concentration of MHD was only mildly reduced by the procedure. The areas under the concentration curve of MHD on the first and sixth day of plasmapheresis were 99% and 94%, respectively, of the pre-plasmapheresis values. The results are in agreement with studies on other anticonvulsant medications (carbamazepine, valproic acid, phenobarbital, and phenytoin), indicating that minor fractions (2% to 10%) of body stores of these drugs are depleted during plasmapheresis. The authors conclude that it is unnecessary to adjust the oxcarbazepine dosage when performing single-volume plasma exchanges or even multiple exchanges during an extended period. It is further proposed that plasmapheresis is unlikely to be of therapeutic benefit in the treatment of an oxcarbazepine overdose.

Adolescent↗

PubMed2001

Plasma concentration of topiramate correlates with cerebrospinal fluid concentration.

The authors examined the ratio between the plasma and the cerebrospinal fluid (CSF) concentration of topiramate in 14 adults with epilepsy. Simultaneous trough samples of venous blood and CSF were collected and analyzed as total and unbound concentrations. Concomitant levels were also analyzed of lamotrigine (n = 5) and the relevant oxcarbazepine metabolite, 10-hydroxycarbazepine (n = 3). There was a close correlation between the plasma and the CSF concentration for both the total and unbound concentration of topiramate. The median CSF/plasma ratio of total topiramate was 0.85. The free topiramate concentration in plasma was not different from the free topiramate concentration in CSF. The CSF/plasma ratios showed little variation and were independent of the plasma level for both the total and the unbound levels. The unbound fraction of topiramate was 84% in plasma and 97% in CSF. The CSF concentrations of lamotrigine and 10-hydroxycarbazepine were 50% and 61% of the plasma concentrations, respectively. For topiramate, there is a close correlation between the plasma concentration and the CSF concentration. There does not seem to be a saturable carrier mechanism restricting topiramate transport across the blood-brain barrier. The concentration of topiramate in CSF is equal to the unbound proportion of topiramate in plasma, implying that the delivery of topiramate to the brain occurs via transfer from the unbound plasma pool. Plasma is thus a relevant matrix for therapeutic drug monitoring of topiramate.

Adolescent↗

PubMed2001

Initiation of minute virus of mice DNA replication is regulated at the level of origin unwinding by atypical protein kinase C phosphorylation of NS1.

Minute virus of mice nonstructural protein NS1 is a multifunctional protein that is involved in many processes necessary for virus propagation. To perform its distinct activities in timely coordinated manner, NS1 was suggested to be regulated by posttranslational modifications, in particular phosphorylation. In fact, NS1 replicative functions are dependent on protein kinase C (PKC) phosphorylation, most likely due to alteration of the biochemical profile of the viral product as determined by comparing native NS1 with its dephosphorylated counterpart. Through the characterization of NS1 mutants at individual PKC consensus phosphorylation sites for their biochemical activities and nickase function, we were able to identify two target atypical PKC phosphorylation sites, T435 and S473, serving as regulatory elements for the initiation of viral DNA replication. Furthermore, by dissociating the energy-dependent helicase activity from the ATPase-independent trans esterification reaction using partially single-stranded substrates, we could demonstrate that atypical PKC regulation of NS1 nickase activity occurs at the level of origin unwinding prior to trans esterification.

Adenosine Triphosphatases↗

PubMed2001

Minute virus of mice initiator protein NS1 and a host KDWK family transcription factor must form a precise ternary complex with origin DNA for nicking to occur.

Parvoviral rolling hairpin replication generates palindromic genomic concatemers whose junctions are resolved to give unit-length genomes by a process involving DNA replication initiated at origins derived from each viral telomere. The left-end origin of minute virus of mice (MVM), oriL, contains binding sites for the viral initiator nickase, NS1, and parvovirus initiation factor (PIF), a member of the emerging KDWK family of transcription factors. oriL is generated as an active form, oriL(TC), and as an inactive form, oriL(GAA), which contains a single additional nucleotide inserted between the NS1 and PIF sites. Here we examined the interactions on oriL(TC) which lead to activation of NS1 by PIF. The two subunits of PIF, p79 and p96, cooperatively bind two ACGT half-sites, which can be flexibly spaced. When coexpressed from recombinant baculoviruses, the PIF subunits preferentially form heterodimers which, in the presence of ATP, show cooperative binding with NS1 on oriL, but this interaction is preferentially enhanced on oriL(TC) compared to oriL(GAA). Without ATP, NS1 is unable to bind stably to its cognate site, but PIF facilitates this interaction, rendering the NS1 binding site, but not the nick site, resistant to DNase I. Varying the spacing of the PIF half-sites shows that the distance between the NS1 binding site and the NS1-proximal half-site is critical for nickase activation, whereas the position of the distal half-site is unimportant. When expressed separately, both PIF subunits form homodimers that bind site specifically to oriL, but only complexes containing p79 activate the NS1 nickase function.

Adenosine Triphosphate↗

PubMed2001

Epidemiological concepts regarding disease monitoring and surveillance.

Definitions of epidemiological concepts regarding disease monitoring and surveillance can be found in textbooks on veterinary epidemiology. This paper gives a review of how the concepts: monitoring, surveillance, and disease control strategies are defined. Monitoring and surveillance systems (MO&SS) involve measurements of disease occurrence, and the design of the monitoring determines which types of disease occurrence measures can be applied. However, the knowledge of the performance of diagnostic tests (sensitivity and specificity) is essential to estimate the true occurrence of the disease. The terms, disease control programme (DCP) or disease eradication programme (DEP), are defined, and the steps of DCP/DEP are described to illustrate that they are a process rather than a static MO&SS.

Animal Diseases↗

PubMed2001

Automatic external defibrillator intervention in the workplace. A comprehensive approach to program development.

1. The planning and implementation of an automatic external defibrillator (AED) intervention in the workplace necessitates a comprehensive approach to program development. 2. Initiation of an AED intervention program at the worksite, based on an informed decision, requires each company to conduct a detailed assessment of need. 3. Prior to initiating an AED intervention program, appropriate resources should be consulted to examine national, state, and local law provisions and legal factors governing AED use in each specific community. 4. Essential components of an AED intervention program include: the combined cardiopulmonary resuscitation and AED use training program; written policies, procedures, and medical directives; a plan for the purchase, maintenance, and location of the AED equipment and supplies; an integrated emergency response plan; and an ongoing quality improvement process.

Electric Countershock↗

PubMed2000

Herd-level interpretation of test results for epidemiologic studies of animal diseases.

Correct classification of the true status of herds is an important component of epidemiologic studies and animal disease-control programs. We review theoretical aspects of herd-level testing through consideration of test performance (herd-level sensitivity, specificity and predictive values), the factors affecting these estimates, and available software for calculations. We present new aspects and considerations concerning the effect of precision and bias in estimation of individual-test performance on herd-test performance and suggest methods (pooled testing, targeted sampling of subpopulations with higher prevalence, and use of combinations of tests) to improve herd-level sensitivity when the expected within-herd prevalence is low.

Animal Diseases↗

PubMed2000

Prevalence of subclinical Salmonella enterica infection in Danish finishing pig herds.

Our aim was to determine the Salmonella enterica prevalence in 96 randomly selected Danish pig herds, based on serological examination of blood samples and bacteriological examination of faecal samples (collected simultaneously from the same pens). For comparison, 39 high-seroprevalence herds were included in the study. The representativeness of the selected herds was assessed, based on descriptive statistics of herd size and type. Totals of 1330 pen samples and 6814 blood samples were examined.The results from the meat-juice screening in the Danish S. enterica Control Programme were available for 3372 meat-juice samples from 91 of the 96 randomly selected herds and 1195 meat-juice samples from 37 of the 39 high-seroprevalence herds. Of the 96 randomly selected herds, 23 herds had no positive pen samples (out of 10), no positive blood samples (out of 50) and no positive meat-juice samples (out of approximately 30-40 samples in 6 months). Ten herds had one or more positive meat-juice samples but were otherwise negative. S. Typhimurium was isolated from 30 of the 39 high-seroprevalence herds. Our conclusions were: (1) The within-herd seroprevalence among the 96 randomly selected Danish pig herds was low (average within-herd seroprevalence=2%, maximum=32%). (2) Among the 39 high-seroprevalence herds (recently assigned level 3 in the S. enterica Control Programme), S. enterica was isolated from 77% of the herds when 10 pen samples were examined bacteriologically. (3) Seropositivity tended to be related to the presence of S. Typhimurium.

Animals↗

PubMed2000

Hiatus hernia: a review of evidence for its origin in esophageal longitudinal muscle dysfunction.

The axial forces exerted on the esophagus by the swallowing-induced contraction of its two longitudinally oriented muscle layers should, if unopposed, herniate the cardia through the diaphragm. A mathematical model of esophageal contraction shows that the magnitude of such a force becomes maximal just above the cardia, which is consistent with anatomic evidence of the existence of an inhibitory innervation in this same region. We propose that the inhibition exerted by these nerves when they discharge in swallowing prevents the supracardiac esophagus from shortening, allowing it to stretch and dissipating the pulling force of longitudinal muscle contraction above the diaphragm. Thus, hiatal hernia could originate from nerve disease, alteration in the viscoelastic properties of distal esophagus, or increased strength of the longitudinal muscle layers.

Adolescent↗

PubMed2000

Comparative investigations of Listeria monocytogenes isolated from a turkey processing plant, turkey products, and from human cases of listeriosis in Denmark.

Listeria monocytogenes was isolated from critical control points in a Danish turkey processing plant, from turkey products and from cases of human listeriosis. During processing in the plant the prevalence of L. monocytogenes ranged from 25.9 to 41.4%. Cleaning and disinfection decreased the prevalence to 6.4%. Isolates of L. monocytogenes were characterized by pulsed-field gel electrophoresis (PFGE) using restriction endonuclease ApaI. Identical DNA types were obtained from turkey products and the processing line even after cleaning and disinfection. Two identical DNA types were demonstrated among isolates from turkey products and human cases of listeriosis. The prevalence of L. monocytogenes in turkey products ranged from 7.3 to 17.4% for ready-to-eat products and raw products, respectively. Since none of the 27 flocks examined before slaughter sampled positive for L. monocytogenes and the prevalence increased during processing, the potential risk from turkey meat was apparently due to factory hygiene rather than intrinsic contamination of the turkeys.

Animals↗