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Biomedical subjects

K H Jensen

Publications and source records attributed to K H Jensen.

At least 19 recordsLinked to original sources
PubMed2006

Experimental investigation of pneumatic soil vapor extraction.

Soil Vapor Extraction (SVE) is a common remediation technique for removing volatile organic compounds from unsaturated contaminated soils. Soil heterogeneities can however cause serious limitations to the applicability of SVE due to air bypassing low permeable areas of the soil, leading to diffusion limitation of the remediation. To enhance removal from areas subject to diffusion limitation a new remediation technique, pneumatic soil vapor extraction, is proposed. In contrast to traditional SVE, in which soil vapor is extracted continuously by a vacuum pump, pneumatic SVE is based on enforcing a sequence of large pressure drops on the system to enhance the recovery from the low-permeable areas. The pneumatic SVE technique was investigated in the laboratory using TCE as a model contaminant. 2D-laboratory tank experiments were performed on homogeneous and heterogeneous sand packs. The heterogeneous packs consisted of a fine sand lens surrounded by a coarser sand matrix. As expected when using traditional SVE, the removal of TCE from the low permeable lens was extremely slow and subject to diffusion limitation. In contrast when pneumatic venting was used removal rates increased by up to 77%. The enhanced removal was hypothesized to be attributed to mixing of the contaminated air inside the lens and generation of net advective transport out of the lens due to air expansion.

Air Movements↗
PubMed2006

Immune response to a killed infectious bursal disease virus vaccine in inbred chicken lines with different major histocompatibility complex haplotypes.

The influence of MHC on antibody responses to killed infectious bursal disease virus (IBDV) vaccine was investigated in several MHC inbred chicken lines. We found a notable MHC haplotype effect on the specific antibody response against IBDV as measured by ELISA. Some MHC haplotypes were high responders (B201, B4, and BR5), whereas other MHC haplotypes were low responders (B19, B12 and BW3). The humoral response of 1 pair of recombinants isolated from a Red Jungle Fowl (BW3 and BW4) being identical on BF and BG, but different on BL, indicated that part of the primary vaccine response was an MHC II restricted T-cell dependent response. The humoral response in another pair of recombinant haplotypes originating in 2 different White Leghorn chickens being BF21, BL21, BG15 (BR4) and BF15, BL15, BG21 (BR5) on the MHC locus indicated that the BG locus may perform an adjuvant effect on the antibody response as well. Vaccination of chickens at different ages and in lines with different origin indicated that age and background genes also influence the specific antibody response against inactivated IBDV vaccine.

Animals↗
PubMed2005

Molecular characterization of major histocompatibility complex class I (B-F) mRNA variants from chickens differing in resistance to Marek's disease.

In this study, the relative distributions of two alternatively polyadenylated chicken major histocompatibility complex (MHC) mRNA isoforms of approximately 1.5 and 1.9 kb were analysed in spleen cells from chickens homozygous for the MHC haplotypes B21 and B19v1 as well as in heterozygous B19v1/B21 birds. Both isoforms are likely to encode classical MHC class I (B-F) alpha chains. The B19v1 and B21 MHC haplotypes confer different levels of protection against Marek's disease (MD), which is caused by infection with MD virus (MDV). In spleen cells, MD-resistant B21 birds were shown to have the highest percentage of the 1.5 kb variant relative to the total MHC class I expression, MD-susceptible B19v1 birds the lowest and B19v1/B21 birds an intermediate percentage. Infection of 4-week-old chickens with the GA strain of MDV was shown to cause a significant increase in the relative amount of 1.5 kb transcripts in B21 birds 32 days postinfection (dpi). Alternatively polyadenylated mRNA isoforms may encode identical proteins, but differences in the 3' untranslated region (UTR) can influence polyadenylation, mRNA stability, intracellular localization and translation efficiency. It was shown that the increased 1.5 kb percentage in B21 birds 32 days postinfection may be a result of a change in the choice of poly(A) site rather than a locus-specific upregulated transcription of the BF1 gene that preferentially expresses the 1.5 kb variant. Furthermore, the 3' end of the 1.5 kb mRNA variants deriving from B19v1 and B21 chickens was characterized by Rapid Amplification of cDNA Ends (RACE) and sequencing. No potentially functional elements were identified in the 3' UTR of the RACE products corresponding to this short isoform. However, variation in polyadenylation site was observed between the BF1 and BF2 mRNA transcripts and alternative splicing-out of the sequence (exon 7) encoding the second segment of the cytoplasmic part of the mature BF2*19 molecules. This alternative exon 7 splice variant was also detected in other MD-susceptible haplotypes, but not in the MD-resistant B21 and B21-like haplotypes, suggesting a potential role of exon 7 in MHC-related MD resistance.

3' Untranslated Regions↗
PubMed2004

Remediation of NAPL below the water table by steam-induced heat conduction.

Previous experimental studies have shown that NAPL will be removed when it is contacted by steam. However, in full-scale operations, steam may not contact the NAPL directly and this is the situation addressed in this study. A two-dimensional intermediate scale sand box experiment was performed where an organic contaminant was emplaced below the water table at the interface between a coarse and a fine sand layer. Steam was injected above the water table and after an initial heating period the contaminant was recovered at the outlet. The experiment was successfully modeled using the numerical code T2VOC and the dominant removal mechanism was identified to be heat conduction induced boiling of the separate phase contaminant. Subsequent numerical modeling showed that this mechanism was insensitive to the porous medium properties and that it could be evaluated by considering only one-dimensional heat conduction.

Environmental Monitoring↗
PubMed2004

On spurious water flow during numerical simulation of steam injection into water-saturated soil.

Numerical simulation of steam injection into a water-saturated porous medium may be hindered by unphysical behavior causing the model to slow down. We show how spurious water flow may arise on the boundary between a steam zone and a saturated zone, giving rise to dramatic pressure drops. This is caused by the discretization of the temperature gradient coupled with the direct relation between pressure and temperature in the steam zone. The problem may be a severe limitation to numerical modeling. A solution is presented where the spurious water flow is blocked and this widely enhances the performance of the model. This new method is applied to a previously reported example exhibiting numerical problems. Furthermore, it is applied to the simulation of 2-D sandbox experiments where LNAPL is remediated from a smearing zone by steam injection. These experiments would have been difficult to analyze numerically without the adjustment to prevent spurious flow.

Computer Simulation↗
PubMed2002

Platinum group elements in the feathers of raptors and their prey.

Platinum (Pt), palladium (Pd), and rhodium (Rh) concentrations were determined in the feathers of three raptor species in Sweden, the sparrowhawk ( Accipiter nisus), the peregrine falcon ( Falco peregrinus), and the gyrfalcon ( Falco rusticolus), as well as the main prey of the sparrowhawk (the house sparrow, Passer domesticus) and the gyrfalcon (the willow grouse, Lagopus lagopus). The analysis of feathers from 1917-1999 revealed a clear temporal trend, with significantly higher Rh concentrations in sparrowhawk and peregrine falcon after 1986. There is evidence for increasing platinum group element (PGE) concentrations from 1917 to 1999 in peregrine falcon and sparrowhawk. This suggests that feathers reflect increased PGE concentrations in the environment over this time period. Mean concentrations of PGE in feathers of raptors after 1986 ranged from 0.3 to 1.8 ng x g(-1) for Pt, 0.6 to 2.1 ng x g(-1) for Pd (indicative values), and 0.1 to 0.6 ng x g(-1) for Rh. House sparrows in urban areas had significantly higher Pt and Pd concentrations than urban sparrowhawks. The higher Pd concentrations in relation to Pt and Rh may indicate the greater mobility of Pd in the environment. Although PGE concentrations are generally higher in birds living in urban areas, no significant spatial trend could be established. This is partly due to the widespread distribution of automobiles and partly because birds forage and integrate PGE exposure over large areas. Laser ablation analysis demonstrates that PGE contamination of feathers is predominantly external, consisting of small particles in the nanometer size range. Other indications of external contamination are that Pt and Pd levels are significantly higher in the vane than in the shaft and that PGE relative ratios (except Pd) reflect urban particles.

Animals↗
PubMed2002

Removal of NAPLs from the unsaturated zone using steam: prevention of downward migration by injecting mixtures of steam and air.

Steam injection for remediation of porous media contaminated by nonaqueous phase liquids has been shown to be a potentially efficient technology. There is, however, concern that the technique may lead to downward migration of separate phase contaminant. In this work, a modification of the steam injection technology is presented, where a mixture of steam and air was injected. In two-dimensional experiments with unsaturated porous medium contaminated with nonaqueous phase liquids, it was demonstrated how injection of pure steam lead to severe downward migration. Similar experiments, where steam and air were injected simultaneously, resulted in practically no downward migration and still rapid cleanup was achieved. The processes responsible for the prevention of downward migration when injecting steam-air mixtures were analyzed using a nonisothermal multiphase flow and transport model. Hereby, three mechanisms were identified and it was demonstrated how the effectiveness of these mechanisms depended on the air-to-steam mixing ratio.

Air↗
PubMed2001

De novo identification of cell-type specific antibody-antigen pairs by phage display subtraction. Isolation of a human single chain antibody fragment against human keratin 14.

The aim of this study was to identify novel antibodies directed against cytosolic keratinocyte-specific antigens from a phage display antibody repertoire by using phage display subtraction. Phage display is a method of displaying foreign molecules on the surface of filamentous bacteriophage particles. It allows the interaction between two cognate molecules to be analysed through affinity selections. Recently, large repertoires of phage displayed human antibody fragments have been constructed. From such repertoires, antibodies can be obtained in vitro without the need for immunization or the hybridoma technology. A novel subtractive strategy for selecting antibodies from phage libraries was applied. Phage antibodies were selected against immobilized crude lysates of cultured human keratinocytes, the target antigens being unknown beforehand. A competing cell lysate was used to reduce retrieval of phage antibodies with specificities to commonly non-differentially expressed antigens. A monoclonal single chain fragment variable (scFv) with specificity for crude lysates of cultured human keratinocytes was identified as demonstrated by ELISA assays and immunoblotting analysis. The cognate keratinocyte antigen was shown to be keratin 14 (K14) by using immunoblotting based on 2D PAGE and a corresponding 2D PAGE protein database. In accordance with the expected tissue localization of K14, the identified scFv stained the basal layer of human epidermis by indirect immunofluorescence analysis. Starting with crude cell lysates, phage display subtraction in combination with 2D PAGE and 2D PAGE protein databases can be used to identify antibody-antigen pairs that characterize a specific cell type.

Blotting, Western↗
PubMed2001

Arthroscopic shoulder surgery with epinephrine saline irrigation.

PURPOSE: To determine whether dilute epinephrine saline irrigation (0.33 mg/L) delivered by a pressure-controlled pump would significantly reduce intraoperative bleeding during routine arthroscopic shoulder surgery and, in addition, to investigate potential adverse cardiovascular reactions of adding epinephrine to the irrigation fluid. TYPE OF STUDY: Prospective, randomized, double-blinded, placebo-controlled study. METHODS: Fifty-four patients requiring arthroscopic shoulder surgery were randomly assigned to either an epinephrine group that received dilute epinephrine irrigation by a pressure-controlled pump or to a placebo group that received plain saline irrigation by a pressure-controlled pump. Intraoperative, intra-articular bleeding was estimated by multiplying the total volume of the irrigation fluid used with the hemoglobin concentration in the irrigation fluid. Postoperatively, the surgeon rated the clarity of the visual field during the arthroscopy by a visual analogy scale. RESULTS: Intraoperative bleeding was significantly reduced (P =.008) and the clarity of the visual field was significantly better (P =.0007) in the group of patients receiving dilute epinephrine irrigation compared with the group of patients without epinephrine added to the irrigation fluid. CONCLUSIONS: The addition of epinephrine to irrigation fluid seems to reduce intra-articular bleeding during routine arthroscopic shoulder surgery and may improve visualization. Furthermore, no cardiovascular adverse reactions were observed resulting from the intra-articular epinephrine administration.

Adult↗
PubMed2000

Identification of phage antibodies toward the Werner protein by selection on Western blots.

A procedure was established for selecting phage antibodies (phage-abs) from phage-displayed antibody repertoires by panning against proteins, separated by sodium dodecyl phosphate-polyacrylamide gel electrophoresis (SDS-PAGE) and electroblotted onto nitrocellulose membranes (Western blots). This immobilization strategy is applicable for secondary rounds of panning in selections against semipurified proteins, and directs the selection toward antibodies suitable as immunochemical reagents in Western blots. In model experiments, enrichment factors as high as 1.9x10(5) were obtained in a single round of panning. Furthermore, we demonstrate the application of this approach by selection of phage-abs recognizing the human Werner protein, which is defective in a premature aging syndrome.

Antibodies, Viral↗
PubMed2000

A simplified technique for non-surgical catheterization of the vena cava cranialis in pigs and an evaluation of the method.

Restraint and venepuncture affect blood parameters and are stressful for pigs. Therefore, when experiments require frequent blood sampling, catheterization is the best option, both ethically and scientifically. A simplified non-surgical method for catheterization of the vena cava cranialis in sows is described. The vena cava is catheterized via the vena jugularis externa, which is punctured while the sow is restrained by nose snaring. The procedure can be carried out by two experimenters in 5 min, it requires little equipment and can be performed under farm or very simple experimental conditions. Results from 89 catheterizations are reported. Seventy-three of the catheters remained functional for 5 days or more. There was a tendency for a higher success rate in dry sows than in highly pregnant sows. The only behavioural effect observed after catheterization was a short-lasting increase in motivation for wallowing in some sows. No illness that could be attributed to the catheterization occurred.

Animals↗
PubMed1999

Isolated total ruptures of the anterior cruciate ligament--a clinical study with long-term follow-up of 7 years.

Seventy patients met our inclusion criteria in this retrospective study, all with an arthroscopic/arthrotomic-verified isolated total anterior cruciate ligament (ACL)-rupture and a minimum follow-up period of 3 years and no associated lesions. Due to emigration/death, 3 patients were not available for follow-up. Of the remaining 67, 25 patients underwent secondary ACL-reconstruction, equivalent to a failure rate of the initial non-operative treatment of 37%. All patients were initially treated conservatively. This left 42 patients for follow-up--9 answered a questionnare and 33 went through follow-up examination after a median of 7.1 years (range 3.3 14.6) including IKDC-evaluation form, Lysholm & Tegner score, ES-SKA-score, clinical examination and Stryker Laxity test. In the present study all values represent the 33 patients available for follow-up. Soccer, handball and alpine skiing were most frequently responsible for the injury. We observed in the 33 patients a decline in median Lysholm score from 100 (90-100) pretraumatic to 86 (42-100) at follow-up, and a decrease in median Tegner values from 7 (3-9) pretraumatic to 5 (2-7) at follow-up. All but 2 patients demonstrated a decline in Lysholm score, and only 3 patients returned to their preinjury level. According to the ESSKA-classification, the number of "cutting-sports performers" declined dramatically from 24 to 2. All but one patient ascribed their decline in activity to their knee status. The Stryker-measured AP-translocations were significantly higher on the injured knee (7.27) compared to the healthy knee (4.80) (P < 0.05). Intermittant rest pain was suffered by 63% of the patients. During the time from inclusion until follow-up, 13 (39%) patients sustained an additional ipsilateral knee lesion, most commonly a tear of the medial meniscus. The overall outcome was expressed in a low frequency of return to unrestricted preinjury level of function, and a high level of instability complaints resulting in many secondary ACL-reconstructions. Naturally some have adapted to their ultimate functional disability, but only through modification of activities, and the overall outcome after conservative therapy of these ACL-ruptures was not satisfactory.

Adolescent↗
PubMed1998

[Traumatic knee luxation].

This report is based on two case stories. Traumatic knee dislocation is a rare but serious event. There is extensive damage to the ligaments of the knee, but the vascular lesions, with an incidence of approximately 29% are of primary concern. Signs of ischaemia indicate arteriography or exploration, and if the vascular lesion is repaired within eight hours, the majority can avoid amputation. Complicating fractures, ligament lesions and nerve lesions have secondary priority to arterial lesions. A combination of surgical ligament-repair/reconstruction and intensive rehabilitation seems the most promising.

Adult↗
PubMed1997

Retrieval of phage displayed scFv fragments using direct bacterial elution.

Phage displayed repertoires of antibody fragments, either single chain Fv (scFv) or Fab, have become a real alternative to traditional hybridoma technology in the generation of monoclonal antibodies. The steps usually taken in the selection from such repertoires were analysed and the necessity of chemical elution of bound phage-Abs and precipitation of amplified phage particles questioned. By using a semi-synthetic scFv library as a source, phage antibodies recognising a panel of seven antigens were isolated utilising direct bacterial elution of bound phage. Selections against two antigens were subsequently performed with bacterial or chemical elution in parallel and the resulting pools of phage antibodies compared. It is demonstrated that direct bacterial elution can be used when selecting from phage displayed antibody repertoires but that the enrichment of high affinity binders might be jeopardised. In addition, a simplified and more rapid scheme for amplification and use of phage displayed repertoires is described.

Antibodies, Monoclonal↗
PubMed1997

[Prevalence of left ventricular hypertrophy in Danish patients with hypertension].

The aim of this investigation was to study the prevalence of left ventricular hypertrophy (LVH) in a hypertensive population with reference to a normotensive control group. From the general population, 3498 men and women aged 35, 45, 55 and 65 years old were invited to a health examination. Participants with blood pressure above 160 mmHg systolic and/or 95 mmHg diastolic or participants currently taking antihypertensive medication or having done so during the previous six months were asked to undergo an echocardiographic examination. Controls were randomly selected from the same population. Of 552 participants in the final study population, 194 were normotensive controls and 358 were in the hypertensive group. Echocardiographic measurements were made according to the "Penn" conventions and indexed for body surface. Cutoff values for LVH were 134 grams per m2 for males and 102 grams per m2 for women. Overall, we found that the prevalence of 1 VH was 14%/20% (men/women) in normotensives and 25%/26% in hypertensives (p < 0.01). By subdivision in age and sex groups we found that the relation between normotensives and hypertensives was significant in the age group of 65 years (p < 0.02 for males and p < 0.05 for females). The association between blood pressure and 1 VH in the general population is weak. 1 VH is only significantly more frequent among hypertensives as compared to normotensives in older people.

Aged↗
PubMed1997

[Osteochondritis dissecans of the acetabulum].

A case of osteochondritis dissecans (OD) of the acetabulum in a 14-year-old girl is presented. The initial clinical manifestation was hip pain and restricted movements of the joint. Magnetic Resonance Imaging confirmed the diagnosis. The patient was treated conservatively, using crutches. One year after the first examination, no clinical improvements were found. X-rays of the hip showed increased sclerosis around the osteochondritis-segment, indicating incipient healing. The patient is still conservatively treated, with regular clinical examinations. The diagnosis should be remembered in the case of patients with unexplained hip-pain, and may require magnetic resonance imaging for confirmation.

Acetabulum↗
PubMed1997

Isolated partial rupture of the anterior cruciate ligament. Long-term follow-up of 56 cases.

The majority of previous studies on partial ruptures of the anterior cruciate ligament (ACL) include a relatively large proportion of knees with associated intra-articular injury or collateral ligament tear that contributes to an increase in the symptoms of instability and further deterioration of knee function. In the present study only patients with isolated, partial ruptures of the ACL were evaluated. Fifty-six patients with one injured knee were examined after a median of 5.3 (range 2.0-12.7) years using the IKDC evaluation form, Lysholm knee function score and Tegner activity score. Of the 56 knees, 6 underwent autologous reconstruction due to early progression to complete rupture. Of 34 knees evaluated for laxity, 25 had a negative Lachman test and 7 a positive (+) Lachman. In 2 knees a Lachman ++ result and a positive pivot shift were found. With instrumented laxity testing 24 knees had 2 mm or less difference in laxity compared with the contralateral uninjured knee. The largest side-to-side difference in knee laxity was 4.5 mm. Lysholm score was median 86 (range 52-100) points, and 62% had good or excellent knee function. A significant decline in activity was seen. Only 10 patients (30%) resumed their preinjury activities. We find that the majority of patients with an isolated, partial rupture of the ACL have an acceptable knee function and a stable knee after a median 5 years follow-up. There is, however, a marked reduction in activity.

Adolescent↗