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Biomedical subjects

K Hansen

Publications and source records attributed to K Hansen.

At least 109 records · Page 6Linked to original sources
PubMed1997

Serine protein kinase activity associated with rotavirus phosphoprotein NSP5.

The rotavirus nonstructural protein NSP5, a product of the smallest genomic RNA segment, is a phosphoprotein containing O-linked N-acetylglucosamine. We investigated the phosphorylation of NSP5 in monkey MA104 cells infected with simian rotavirus SA11. Immunoprecipitated NSP5 was analyzed with respect to phosphorylation and protein kinase activity. After metabolic labeling of NSP5 with 32Pi, only serine residues were phosphorylated. Separation of tryptic peptides revealed four to six strongly labeled products and several weakly labeled products. Phosphorylation at multiple sites was also shown by two-dimensional polyacrylamide gel electrophoresis (PAGE), where several isoforms of NSP5 with different pIs were identified. Analysis by PAGE of protein reacting with an NSP5-specific antiserum showed major forms at 26 to 28 and 35 kDa. Moreover, there were polypeptides migrating between 28 and 35 kDa. Treatment of the immunoprecipitated material with protein phosphatase 2A shifted the mobilities of the 28- to 35-kDa polypeptides to the 26-kDa position, suggesting that the slower electrophoretic mobility was caused by phosphorylation. Radioactive labeling showed that the 26-kDa form contained additional phosphate groups that were not removed by protein phosphatase 2A. The immunoprecipitated NSP5 possessed protein kinase activity. Incubation with [gamma-32P]ATP resulted in 32P labeling of 28- to 35-kDa NSP5. The distribution of 32P radioactivity between the components of the complex was similar to the phosphorylation in vivo. Assays of the protein kinase activity of a glutathione S-transferase-NSP5 fusion polypeptide expressed in Escherichia coli demonstrated autophosphorylation, suggesting that NSP5 was the active component in the material isolated from infected cells.

Animals↗
PubMed1997

Systemic immune changes following meal intake in humans.

Food intake represents a high intestinal antigen exposition requiring host defense. Besides local immune activation, this defense includes a coordinate systemic immune response, which may serve to support local immunity. This study examined influences of a standardized high-protein meal on peripheral blood mononuclear cell counts; on the in vitro mitogen-stimulated production of tumor necrosis factor-alpha, interleukin-1 beta, interleukin-6, and interferon-gamma; on the in vivo plasma levels of tumor necrosis factor-alpha and interleukin-6; and on plasma concentrations of cortisol and growth hormone. Ten healthy men (18-35 yr) participated in two experimental sessions in a balanced order. On one occasion, subjects fasted; on the other, they received a high-protein meal at 1230. Blood was sampled every 15 min. Whereas the numbers of neutrophils and platelets were increased for more than 2.5 h after meal intake (P < 0.01) lymphocyte counts decreased (P < 0.01). Meal intake also decreased the production of interferon-gamma but did not affect the production and plasma levels of the other cytokines. Changes in immune cell distribution and function were accompanied by a strong postprandial rise in plasma cortisol concentrations. Some of the systemic immune changes, like the emigration of lymphocytes, probably into extravascular abdominal tissues, may serve to support local immune defense.

Adult↗
PubMed1997

Lyme carditis: a clinical presentation and long time follow-up.

The acute disease and a follow-up carried out up to 7 years after definite Lyme carditis in 6 patients is described. At the time of diagnosis all 6 patients had 2-3 degrees AV block, 4 patients presented with syncopes, and 1 revealed episodes of non-sustained ventricular tachycardia. The diagnosis of Lyme carditis was confirmed by Borrelia burgdorferi-specific IgM and IgG antibody determinations in consecutive serum samples. All patients were treated with antibiotics. At follow-up, a clinical examination, a 2D and M-mode echocardiogram, and an exercise test did not reveal sequelae to Lyme carditis.

Adult↗
PubMed1996

Mutation of a Src phosphorylation site in the PDGF beta-receptor leads to increased PDGF-stimulated chemotaxis but decreased mitogenesis.

Ligand induced activation of the beta-receptor for platelet-derived growth factor (PDGF) leads to activation of Src family tyrosine kinases. We have explored the possibility that the receptor itself is a substrate for Src. We show that Tyr934 in the kinase domain of the PDGF receptor is phosphorylated by Src. Cell lines expressing a beta-receptor mutant, in which Tyr934 was replaced with a phenyalanine residue, showed reduced mitogenic signaling in response to PDGF-BB. In contrast, the mutant receptor mediated increased signals for chemotaxis and actin reorganization. Whereas the motility responses of cells expressing wild-type beta-receptors were attenuated by inhibition of phosphatidylinositol 3'-kinase, those of cells expressing the mutant receptor were only slightly influenced. In contrast, PDGF-BB-induced chemotaxis of the cells with the mutant receptor was attenuated by inhibition of protein kinase C, whereas the chemotaxis of cells expressing the wild-type beta-receptor was less affected. Moreover, the PDGF-BB-stimulated tyrosine phosphorylation of phospholipase C-gamma was increased in the mutant receptor cells compared with wild-type receptor cells. In conclusion, the characteristics of the Y934F mutant suggest that the phosphorylation of Tyr934 by Src negatively modulates a signal transduction pathway leading to motility responses which involves phospholipase C-gamma, and shifts the response to increased mitogenicity.

Actins↗
PubMed1996

Stable expression of homomeric AMPA-selective glutamate receptors in BHK cells.

cDNAs encoding glutamate receptor glu1, glu2 (Q and R) or glu4 under control of a constitutively active metallothionine promoter, were transfected into baby hamster kidney cells. Following the addition of selection agent, transfectants expressing high levels of glutamate receptor as measured by [3H]alpha-amino-3-hydroxyl-5-methyl-isoxalazole-4-propionate (AMPA) binding, were selected for further studies. Using glutamate receptor antibodies, the receptor proteins were visualized in Western blotting as having a molecular weight of approximately 100 kDa. [3H]AMPA binding to the glutamate receptor expressing cell lines revealed that glu1, glu2 (Q), and glu4 receptors displayed a single site in Scatchard analysis with Kd values of 12, 15.7 and 21 nM, respectively. However, the Ca2+ impermeable variant of the glu2 receptor, glu2 (R) displayed a curvilinear Scatchard plot. Computer resolution suggested the presence of a high and low affinity state (KH = 2.9 nM; KL = 40.7 nM). The pharmacological profile of the [3H]AMPA binding to these recombinant receptors resembled the high affinity [3H]AMPA binding site in rat brain showing high affinity for glutamate, quisqualate, and medium affinity for 6-cyano-7-nitro-quinoxaline-2,3-dione, CNQX; 6,7-dinitro-quinoxaline-2,3-dione, DNQX; and 6-nitro-7-sulphanyl-benzo(f)quinoxaline-2,3,dione, NBQX. Kainate displayed low affinity and N-methyl-D-aspartate (NMDA), was inactive in inhibiting specific [3H]AMPA binding. These cell lines will prove to be important tools in the study of glutamate receptors.

Animals↗
PubMed1996

Fatty acid composition of Danish margarines and shortenings, with special emphasis on trans fatty acids.

Trans fatty acids from hydrogenated vegetable and marine oils could be as hypercholesterolemic and atherogenic as saturated fatty acids. Hence, it is important to know the fatty acid composition in major food contributors, e.g., margarines and shortenings. In 1992 margarines were examined, and in 1995 brands covering the entire Danish market were examined. Significant amounts of trans-18:1 were found only in hard margarines (mean: 4.2 +/- 2.8%) and shortenings (mean: 6.8 +/- 3.1%), whereas the semisoft and soft margarines contained substantially less trans-18:1 in 1995 than in 1992. Where marine oils had been used to a larger degree the mean trans-monoenoic content was about 15%, of which close to 50% was made up of long-chain (C20 and C22) trans fatty acids. A noteworthy decrease in the content of trans-18:1 had occurred for the semisoft margarines, from 9.8 +/- 6.1% in 1992 to 1.2 +/- 2.2% in 1995. Calculated from sales figures, the supply of trans-18:1 plus saturated fatty acids from margarines has decreased over this three-year period by 1.4 g/day, which has been replaced by cis monounsaturated and polyunsaturated fatty acids.

Chromatography, Gas↗
PubMed1996

Analysis of the human antibody response to outer surface protein C (OspC) of Borrelia burgdorferi sensu stricto, B. garinii, and B. afzelii.

The aim of this study was to determine by Western blotting (WB) the prevalence of anti-outer surface protein C (OspC) IgM and IgG antibodies in patients with Lyme borreliosis according to each of the three genospecies of Borrelia burgdorferi sensu lato. Strains of B. burgdorferi sensu stricto (MUL), B. garinii (DK 6), and B. afzelii (DK 26) served as antigen, all of which expressed abundant OspC. We examined sera from 117 patients with untreated early and late Lyme borreliosis, as well as from 100 blood donors and 29 patients with syphilis. WB results were compared with the B. burgdorferi flagellum enzyme-linked immunosorbent assay (ELISA) data. OspC from B. burgdorferi sensu stricto showed the lowest diagnostic sensitivity. OspC from B. garinii and B. afzelii performed almost identically in erythema migrans, with an IgM positive rate of 36% versus 34%, whereas OspC from B. garinii performed best in neuroborreliosis (60% versus 44%). The anti-OspC IgG response was less prominent than the IgM response and was infrequent in the late stages of the disease (0-20%). The benefit of combining the evaluation of anti-OspC responses with all three species was limited. The overall diagnostic sensitivity of WB anti-B. garinii OspC evaluation was, in the early stages of the disease, comparable to the results obtained using the flagellum ELISA. In erythema migrans and neuroborreliosis, the addition of anti-OspC IgM to the flagellum ELISA increased the sensitivity by 15% and 10%, respectively. It can, therefore, be concluded that OspC from B. garinii is a suitable OspC test antigen, and that supplementary use of OspC from other species adds little to the overall diagnostic sensitivity. An ELISA based on B. garinii OspC and native flagella seems currently the most promising concept for a future antibody test in early Lyme borreliosis.

Antibodies, Bacterial↗
PubMed1996

Ovulation induction in clomiphene-resistant anovulatory women with normal dehydroepiandrosterone sulfate levels: beneficial effects of the addition of dexamethasone during the follicular phase.

OBJECTIVE: To evaluate the effect on ovulation of a 10-day course of dexamethasone (DEX) initiated concurrently with a 5-day course of clomiphene citrate (CC) in CC-resistant patients with normal DHEAS levels. DESIGN: Retrospective review. SETTINGS: Patients from the clinical practice of the authors at the Medical College of Georgia, Augusta, Georgia. PATIENTS: Thirteen oligomenorrheic women with normal DHEAS levels who failed to ovulate on a graduated regimen of CC up to a dose of 150 mg for 5 days. INTERVENTIONS: Ten-day course of DEX initiated concurrently with a 5-day course of CC; ovulation and pregnancy outcomes recorded. MAIN OUTCOME MEASURE: Pregnancy. RESULTS: Eleven of 13 women had evidence of ovulation. Five clinical pregnancies were achieved. CONCLUSION: These initial data support improvements in follicular development with an overlapping follicular phase regimen of CC and DEX in patients with normal DHEAS levels and a previous poor response.

Adult↗
PubMed1996

Do the Framingham Safety Surveys improve injury prevention counseling during pediatric health supervision visits?

BACKGROUND: Previous studies suggest that injury prevention counseling by pediatricians is effective but accomplished infrequently. The Framingham Safety Surveys (FSS) are brief questionnaires designed to facilitate physician education of parents regarding injury prevention. OBJECTIVE: To determine whether the FSS improve pediatricians' injury prevention counseling. DESIGN: Nonrandomized comparison of a 4-week baseline period and subsequent intervention periods. SETTINGS: Private practice; university hospital clinic. PATIENTS: Patients coming for health supervision visits. INTERVENTION: Provision to the physician of one of the FSS, completed by the parent just before the health supervision visit. OUTCOME MEASURES: (1) After each visit parents completed a checklist of safety issues discussed by the pediatrician. Injury prevention was compared for the two periods by means of three criteria: number of issues discussed (quantity), identification and discussion of specific high-risk behaviors (efficiency), and recognition of high-risk families (targeting). (2) Each physician's assessment of the value of the FSS was obtained by questionnaire. RESULTS: A total of 144 parents (50 from the private practice, 94 from the clinic) completed checklists during the baseline period, and 168 (38 from the private practice, 130 from the clinic) during the intervention period. Use of the FSS produced no detectable improvement in any of the three measures. Seventy-seven percent of the physicians indicated that the FSS were helpful in educating families about safety, 38% thought that the FSS helped identify high-risk families, and 54% said they would use it again. CONCLUSIONS: Although most physicians believed the FSS were useful, introduction of the surveys as employed in this study did not improve injury prevention counseling.

Adolescent↗
PubMed1996

Agenesis of mandibular second premolars. Spontaneous space closure after extraction therapy: a 4-year follow-up.

The aim of this study was to investigate the space closure and occlusal changes in 11 subjects (mean age 11.8 years) with normal occlusion and agenesis of the mandibular second premolar, after extraction of the mandibular secondary primary molar and the maxillary second premolar on the side of the agenesis. The treatment started when the first premolars came into occlusion and the subjects were followed for 4 years. Dental casts were taken at the start of treatment and after 1, 2 and 4 years, and lateral cephalograms were taken at the start of treatment and after 2 and 4 years. Space closure, sagittal movements, rotational movements, and tipping of the first molars and first premolars and dental midline shift were measured on photographs of dental casts. Sagittal movement of the incisors was measured on lateral cephalograms. The results showed that most of the extraction space closed during the first year (55 per cent in the maxilla, 46 per cent in the mandible) and at the end of the follow-up period 89 per cent of the extraction space closed in the maxilla and 80 per cent in the mandible, leaving a mean residual extraction space of 0.9 and 2 mm respectively. In the maxilla, 70 per cent of the extraction space closed by mesial and rotational movements of the first molars. Maxillary premolars moved distally, rotated and tipped only during the first year of observation. In the mandible, the space closure occurred by mesial/rotational movements and tipping of first molars and distal movement and tipping of the first premolars. Unilateral extraction had no influence on the maxillary midline while it caused a statistically significant mandibular dental shift to the extraction side. Extraction therapy had no impact on the overjet, overbite or incisor inclination.

Adolescent↗
PubMed1996

Extracorporeal membrane oxygenation (ECMO) as lung or heart assist.

Extracorporeal membrane oxygenation (ECMO) may serve as extracorporeal lung assist (ECLA) in patients with acute respiratory failure (ARF) or as extracorporeal heart assist (ECHA) in patients with low output syndrome (LOS) after open heart surgery. From 1988 to 1992 seven patients underwent ECMO in our hospital; four suffered from ARF and three from LOS. Various bypass techniques were employed. Two ARF patients, aged 58 and 18 years, had veno-venous bypass; in the latter, ECMO was reinstituted as a veno-arterial bypass one week after weaning. In a three-year-old boy, the ECMO outflow tubing was primarily connected to the pulmonary artery, and shortly afterwards relocated to the common carotid artery. In a 31-year-old man with ARF, and three LOS patients, a 56-year-old woman, and two men aged 68 and 70 years, ECMO was veno-arterial with direct access to the ascending aorta. A heparin-coated system was used, and all but one patient, who was treated with warfarin, received a daily low dose of heparin, which was withdrawn after from one to nine days. Six patients were weaned off ECMO after 4.5 to 21 days. Three ARF patients recovered completely; the child died. In one LOS patient, ECMO was withdrawn due to a poor general condition. Two others were weaned off ECMO and the intra-aortic balloon pump, and the inotropic support was significantly reduced, but both died of multiple system organ failure. Although no firm conclusions can be drawn from these few case reports, the heparin-coated system used as ECLA appears promising, whereas ECHA seems to imply a poor prognosis in patients who are not candidates for cardiac transplantation.

Acute Disease↗
PubMed1996

Refractory ceramic fiber exposure and pleural plaques.

Refractory ceramic fibers (RCF) are manmade vitreous fibers (MMVF) manufactured for high-temperature applications. Between 1987 and 1992, a retrospective cohort and nested case-control study evaluated chest radiographs from 652 workers involved in the manufacture of these fibers for plausibility of a causal relationship between exposure to RCF and chest-radiographic changes. The exposure-response relationship was modeled with three variables: years since first fiber production job, years in fiber production, and cumulative fiber exposure to date of study X-ray. The case-control study used a comprehensive characterization of possible asbestos exposure to investigate asbestos as the potential causative agent of chest-radiographic changes. Chest radiographs of 20 workers (3.1%) demonstrated 19 pleural plaques and one diffuse pleural thickening. Nine of 72 workers (12.5%) with more than 20 yr since their first fiber-production job had plaques (odds ratio [OR] = 9.5; 95% confidence interval [CI] = 1.9 to 48.2). Five of 19 workers with more than 20 yr in fiber-production work (26.3%) had plaques (OR = 22.3; 95% CI = 3.6 to 137.0). Similarly, adjusted ORs demonstrated a progressive relationship between cumulative fiber-months per milliliter (fiber-mo/ml) exposure and plaques. The case-control study confirmed that asbestos exposure did not account for the observed association between fiber exposure and plaques. A validity review of historical films demonstrated biologic plausibility for the association, since sufficient latency existed from the time of first RCF exposure to the development of plaques. There was no significant increase in parenchymal changes consistent with interstitial fibrosis.

Asbestosis↗
PubMed1996

Normotherm continuous blood cardioplegia for 4 hours in an in vivo pig model.

Warm, continuous blood cardioplegia should theoretically maintain cardiac arrest for hours without ischaemic or hypothermic injury. In the absence of in vivo studies of myocardial metabolism and ultrastructural and/or functional preservation during and after more than 2 hours of cardiac arrest and after weaning from bypass, we devised a porcine model with a closed extracorporeal circuit for the heart alone. Normothermic blood cardioplegia was administered antegrade and recirculated for 2 or 4 hours, each in seven pigs. After aortic declamping all were successfully weaned from bypass and reperfused for 1 hour. Thereafter we found no significant intergroup difference in haemodynamic characteristics (average fall in mean arterial pressure 31.7 +/- 3.2% and 26.9 +/- 2.6%) or blood analyses. After 5 and 60 minutes of cardiac arrest there was minimal lactate production (5.7 +/- 10.7 and 0.5 +/- 10.5 nmol/l, respectively), whereas in the remainder of the arrest period there was lactate uptake, indicating aerobic heart metabolism. Our setup avoids systemic hyperkalaemia, gives good cardiac protection with no deterioration between 2 and 4 hours and is well suited for studies on the quiescent, blood-perfused oxygenated heart.

Animals↗
PubMed1995

In vitro screening of traditional medicines for anti-hypertensive effect based on inhibition of the angiotensin converting enzyme (ACE).

Traditional medicines reported to be used as anti-hypertensives or diuretics from different regions in the world (China, India and South America) have been investigated. The bioassay is based on inhibition of ACE, as measured from the enzymatic cleavage of the chromophore-fluorophore-labelled substrate dansyltriglycine into dansylglycine and diglycine. In total, 31 species have been investigated and the crude extracts from seven species inhibit the enzyme by more than 50%.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1995

Colloidal gold conjugated monoclonal antibodies, studied in the BIAcore biosensor and in the Nycocard immunoassay format.

Interactions between immobilized capture monoclonal antibodies (mAbs), analyte molecules and colloidal gold conjugated second monoclonal antibodies have been investigated in the BIAcore biosensor and in the Nycocard immunoassay format. This report focuses on six monoclonal antibodies against human heart myoglobin, although, results with other antigens are also discussed. The BIAcore was used to screen monoclonal antibodies as antigen capture reagents, and for their function as colloidal gold conjugated second antibodies in the Nycocard. Some antibodies with low affinity caused by a rapid antigen dissociation rate, showed high affinity kinetics when used unlabelled or as gold conjugated detector reagents. One gold conjugated mAb with excellent properties in the Nycocard, showed double binding to one epitope, when tested in the BIAcore. The real time visualization of association and dissociation rates was a unique tool in the elucidation of antigen-antibody interactions. Our study confirmed that good antibody candidates selected with the BIAcore must always be tested in their actual conjugation situation before final optimization.

Antibodies, Monoclonal↗