Search PubMed⌕ Search

Biomedical subjects

H Hansen

Publications and source records attributed to H Hansen.

At least 145 records · Page 8Linked to original sources
PubMed1990

Analytical goal setting prior to selection of a method for glycated haemoglobin.

Without a consensus on either a reference method or a single glycated haemoglobin standard, the individual laboratory has to establish and secure its own assay method. Prior to selection of a method for glycated haemoglobin we used an assessment model and defined our clinical goals. Based on clinical goals it was possible to set up goals of analytical quality and evaluate available literature concerning the performance characteristics of different assay methods. We wanted a method that measured HbAlc, without measuring the labile intermediate pre-HbAlc, and that provided separate detection of haemoglobin variants. Low imprecision was required to secure the measured, non-diabetic reference interval, and to minimize random analytical error. We found the isoelectric focusing method the only one able to meet our goals, and a method evaluation was carried out. Clinical goals of analytical quality should always be defined before method selection and implementation. Using this model, we were able to establish a precise isoelectric focusing method that fulfilled our clinical goals by measuring HbAlc with a total coefficient of variation of 2.1% and a non-diabetic reference interval from 5.2% to 6.8% HbAlc.

Blood Chemical Analysis↗
PubMed1989

Novel procedures for derivatization of ribosomes for crystallographic studies.

Undecagold and tetrairidium clusters have been used for the preparation of heavy-metal derivatives of ribosomal particles, necessary for the evaluation of phases in the x-ray structure determination of these large particles. To obtain specific binding, monofunctional reagents of the clusters were prepared and were covalently bound to free sulfhydryl groups on the surface of the ribosome. In addition, a mutant of Bacillus stearothermophilus which lacks one ribosomal protein (BL11) was grown. The heavy-atom clusters were covalently bound to isolated protein BL11, and the modified protein was consequently reconstituted into the mutated ribosomal subunits. Crystallographic data have been collected from crystals of native particles, from the mutated ones, and from the iridium- and gold-derivatized subunits. All these crystal forms are isomorphous within the experimental error.

Crystallization↗
PubMed1989

Functional complementation of catalase-defective peroxisomes in a methylotrophic yeast by import of the catalase A from Saccharomyces cerevisiae.

A mutant of the methanol-utilizing yeast Hansenula polymorpha defective in catalase was isolated. It lacks the ability to grow on methanol as the sole source of carbon and energy due to a loss of peroxisomal function that is required for the dissimilation and assimilation of this substrate. Growth of the mutant on glucose or glycerol was not impaired. Transformation of mutant cells with the gene coding for catalase A from Saccharomyces cerevisiae [Cohen, G., Fessl, F., Traczyk, J., Rytka, J. & Ruis, H. (1985) Mol. Gen. Genet. 200, 74-79] conferred constitutive expression of catalase activity. When the gene was placed under control of the regulatory methanol oxidase promoter from H. polymorpha, high levels of activity subject to glucose repression were obtained. In both cases efficient targeting of catalase A to the heterologous peroxisomes and assembly into an active form could be demonstrated. Concomitantly, growth on methanol was restored in the transformed mutant. The results are in line with a high conservation of transport signals on peroxisomal proteins. Expression of a cytosolic catalase in H. polymorpha did not confer the ability to grow on methanol. Therefore, proper localization of the catalase activity is a prerequisite for peroxisomal function.

Alcohol Oxidoreductases↗
PubMed1989

Determination of cell-bound Fc receptors using a cell adherence test (CAT).

The determination of membrane-bound Fc receptors as rosette forming cells with antibody-coated erythrocytes (EA-RFC) is a tedious and time consuming method. Here, we describe a modification of the assay delineated by Eisenbarth et al. (J. Immunol. Methods (1980) 39, 387) for the detection of Fc receptors on cell surfaces. V-shaped microtiter plates were coated with an antigen (e.g., fluorescein isothiocyanate (FITC) coupled to bovine serum albumin (BSA] and subsequently with monoclonal anti-FITC antibodies of different isotypes. Cells to be tested were added, incubated for a short time or centrifuged immediately. Cells expressing FcR, became bound to the flanks of the V-shaped wells, whereas cells lacking the receptor were pelleted to the tip of the well. This cell adherence test (CAT) is independent of the agglutinating abilities of the antibodies, and since it is very fast and highly reproducible, large numbers of different cells can be screened for FcR expression. Anti-receptor antibodies can also be tested for their binding to FcR.

Animals↗
PubMed1989

Crystals of wild-type, mutated, derivatized and complexed 50 S ribosomal subunits from Bacillus stearothermophilus suitable for X-ray analysis.

Three-dimensional single crystals of wild-type and mutated 50 S ribosomal subunits from Bacillus stearothermophilus, as well as crystals of reconstituted subunits containing heavy-atom clusters and complexes of these subunits with tRNA and a short nascent polypeptide chain, were grown from polyethylene glycol in the presence of salts at low concentrations. Within experimental error, all these crystals are isomorphous, packed with monoclinic symmetry (C2) in unit cells of a = 300 A, b = 546 A, c = 377 (+/- 1%) A and beta = 112 degrees. Using synchrotron radiation at 85 to 100 K they diffract to 11 A resolution and can be irradiated for hours without disintegrating, so that a complete data set could be collected from a single crystal.

Geobacillus stearothermophilus↗
PubMed1989

Epidemiologic and clinical aspects of feline immunodeficiency virus infection in cats from the continental United States and Canada and possible mode of transmission.

The epidemiologic features of feline immunodeficiency virus (FIV) infection were evaluated in 2,765 cats from the United States and Canada. Of these cats, 2,254 were considered by veterinarians to be at high risk for the infection, and 511 were healthy cats considered to be at low or unknown risk. Of the cats in the high-risk group, 318 (14%) were found to be infected with FIV. The infection rate among low- or unknown-risk cats was 6 of 511 (1.2%). Male cats in the high-risk group were 3 times more likely to be infected than were females, similarly as were cats greater than 6 years old, compared with younger cats; domestic cats, compared with purebred cats; and free-roaming cats, compared with confined cats. Feline immunodeficiency virus and FeLV infections did not appear to be linked with each other; 16% of FeLV-infected cats in the high- and low-risk groups were coinfected with FIV. In contrast, there was a pronounced linkage between FIV and feline syncytium-forming virus (FeSFV) infections. Seventy-four percent of FeSFV-infected cats in the high-risk study group were coinfected with FIV, compared with a 38% FIV infection rate among cats that were not infected with FeSFV. The major clinical manifestations associated with FIV infection in cats that were surveyed included chronic oral cavity infections (56%), chronic upper respiratory tract disease (34%), chronic enteritis (19%), and chronic conjunctivitis (11%). Bacterial infections of the urinary tract (cystitis), skin, and ears were seen in a small proportion of cats.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1989

The pathological plica in the knee. Results after arthroscopic resection.

Fifty-three consecutive patients were treated for a symptomatic plica mediopatellaris of the knee joint with arthroscopic resection of the plica. Forty-six patients were followed up 43 months after the operation. Preoperatively, 40% of the patients had anterior knee pain on exertion, and 60% had mechanical symptoms. The symptoms were preceded by a knee trauma in 50% of the patients. The overall results after arthroscopic resection were satisfying, with 80% excellent or good results according to the Lysholm score, and 59% of the patients were completely free of symptoms. The presence of chondromalacia of the patella or femoral condyles or malalignment of the patella did not worsen the results. It is concluded that arthroscopic resection of a pathological plica mediopatellaris generally gives good results, even if other pathology of the knee joint is present.

Adult↗
PubMed1989

Feline immunodeficiency virus infection.

Feline immunodeficiency virus (FIV) (formerly feline T-lymphotropic lentivirus or FTLV) was first isolated from a group of cats in Petaluma, California in 1986. The virus is a typical lentivirus in gross and structural morphology. It replicates preferentially but not exclusively in feline T-lymphoblastoid cells, where it causes a characteristic cytopathic effect. The major structural proteins are 10, 17 (small gag), 28 (major core), 31 (endonuclease?), 41 (transmembrane?), 52 (core precursor polyprotein), 54/62 (reverse transcriptase?), and 110/130 (major envelope) kilodaltons in size. The various proteins are antigenically distinguishable from those of other lentiviruses, although serum from EIAV-infected horses will cross-react with some FIV antigens. Kittens experimentally infected with FIV manifest a transient (several days to 2 weeks) fever and neutropenia beginning 4 to 8 weeks after inoculation. This is associated with a generalized lymphadenopathy that persists for up to 9 months. Most cats recover from this initial phase of the disease and become lifelong carriers of the virus. Complete recovery does not occur to any extent in nature or in the laboratory setting. One experimentally infected cat died from a myeloproliferative disorder several months after infection. The terminal AIDS-like phase of the illness has been seen mainly in naturally infected cats. It appears a year or more following the initial infection in an unknown proportion of infected animals. FIV has been identified in cats from all parts of the world. It is most prevalent in high density populations of free roaming cats (feral and pet), and is very uncommon in closed purebred catteries. Male cats are twice as likely to become infected as females. Older male cats adopted as feral or stray animals are at the highest risk of infection, therefore. The infection rate among freely roaming cats rises throughout life, and reaches levels ranging from less than 1% to 12% or more depending on the area. Clinically affected cats tend to be 5 years or older at the time of hospitalization. Experimental and seroepidemiologic studies suggest that FIV is transmitted mainly by bites. Intimate, non-traumatic contact (mutual grooming, shared use of food, water and litter pans) is inefficient in transmitting the infection. In utero and venereal transmission could not be demonstrated in laboratory settings. There is no statistical linkage between FIV and feline leukemia virus (FeLV) infections in nature. The FeLV infection rate in FIV-infected animals is the same as it is for non-FIV-infected cats.(ABSTRACT TRUNCATED AT 400 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed1989

Personality characteristics and epilepsy.

Patients with a long history of temporal lobe epilepsy or primary generalized epilepsy entered a questionnaire study of personality characteristics, based on a modification of the Bear-Fedio inventory for temporal lobe behavioural syndrome. Psoriasis patients and healthy volunteers served as controls. Four clinical meaningful dimensions of included personality traits were identified: ixoide, ideational, obsessive-compulsive and affective features. Analyses based on the Rasch model approved of all dimensions except for affective features. The epilepsy group obtained the highest scores on all 3 dimensions, healthy volunteers the lowest, while the psoriasis group repeatedly held an intermediate position in all sets of assessment (subjects, interviewers and relatives). A logistic regression analysis showed ixoide features being most important when the entire epilepsy group was compared with other study groups, while the dimension ideational features was significant when the temporal lobe epilepsy group was entered as target group and opposed to primary generalized epilepsy. The intermediate position of the psoriasis group, however, suggests that in addition to the presence of a cerebral dysfunction in the epilepsy group, the mere presence of a chronic disorder with potential social stigmatization influences personality.

Adult↗
PubMed1989

Noninvasive quantitation of regional myocardial oxygen consumption in vivo with [1-11C]acetate and dynamic positron emission tomography.

The usefulness of [1-11C]acetate as a tracer of overall myocardial oxidative metabolism for use with positron emission tomography has been investigated in 12 closed-chest dogs. Myocardial 11C activity clearance kinetics after intravenous administration of [1-11C]acetate in dogs have been determined noninvasively by positron emission tomography. Biexponential fitting of regional myocardial 11C time-activity curves was performed to give clearance half-times and fractional distribution. The rate constant k1 for the early rapid phase of 11C activity clearance was found to correlate linearly with myocardial oxygen consumption (y = 0.0156x + 0.039; SEE = 0.023; r = 0.95). k1 was approximately 7% lower in septal sectors compared with the left ventricular free wall, suggesting that regional oxygen consumption in the septum was lower; a concomitant regional attenuation of blood flow in the septum relative to the left ventricular free wall was also observed. In dogs using carbohydrates as the predominant fuel, k1 oxygen consumption was somewhat more than in dogs using predominantly free fatty acids (0.021 +/- 0.002 compared with 0.018 +/- 0.002, p less than 0.01), indicating that increased carbohydrate consumption is associated with a small increase in k1 at constant oxygen consumption. It is concluded that measurement of myocardial [1-11C]acetate kinetics allows noninvasive determination of cardiac oxygen consumption by positron emission tomography and that the technique is relatively insensitive to myocardial fuel selection.

Acetates↗
PubMed1989

Effects of inhibition of fatty acid oxidation on myocardial kinetics of 11C-labeled palmitate.

The effects of glucose and lactate infusion on palmitate oxidation were compared with the effect of 2-tetradecylglycidic acid (TDGA), an irreversible inhibitor of the carnitine acyltransferase I, in normoxic canine myocardium. The initial capillary transit retention fraction of [1-11C]palmitate and its fractional distribution between oxidation and esterification in myocardium were measured by the residue detection method after intracoronary tracer injection, as well as by effluent measurements of 11CO2, the end product of palmitate oxidation. TDGA reduced the initial capillary transit retention fraction (from 56 +/- 13% to 37 +/- 6%; p less than 0.001) and oxidation of palmitate (n = 19), as also evidenced by the decrease in the fraction of tracer released as 11CO2 from 28 +/- 5% to 6 +/- 3% (p less than 0.001). Infusion of carbohydrate (glucose or lactate; n = 6) reduced 11CO2 production from 30 +/- 7% to 7 +/- 4% (p less than 0.05) but did not alter the initial capillary transit retention fraction of tracer (59 +/- 5% vs. 56 +/- 10%; NS). The latter was due to increased esterification into neutral lipids (41 +/- 11% of injected palmitate after carbohydrate infusion versus 21 +/- 12% in control conditions), as measured from multiexponential curve fittings. When carbohydrates were given after inhibition of palmitate oxidation by TDGA (n = 7), the 11C tissue clearance kinetics were strikingly similar to those observed after carbohydrate infusion alone. Thus, enhanced metabolic trapping of [1-11C]palmitate in myocardium resulted in initial capillary transit retention fractions that were not different from control conditions (41 +/- 5% vs. 48 +/- 12%; NS) despite inhibition of oxidation. The results show that the intracellular metabolism of palmitate contributes to the control of its uptake by myocardium. The findings are consistent with inhibition of palmitate oxidation by carbohydrates occurring at the same site as TDGA.

Animals↗
PubMed1989

The Hodgkin-associated Ki-1 antigen exists in an intracellular and a membrane-bound form.

The Hodgkin-associated Ki-1 antigen occurs in two different molecular forms. The 120-kDa membrane-associated form is a phosphorylated glycoprotein, which is derived from a non-phosphorylated intracellular 84-kDa apoprotein that is co-translationally N-glycosylated with a carbohydrate portion of 6 kDa. The other form of the Ki-1 antigen is a non-glycosylated phosphoprotein of 57 kDa which only occurs intracellularly. Both forms of the antigen are phosphorylated at serine residues. Enzymatic cleavage with sialidase reduced the 120-kDa membrane antigen by about 15 kDa, while its 90-kDa precursor and the 57-kDa intracellular form of the Ki-1 antigen remained unaltered. Pulse-chase experiments revealed that the 57-kDa and 90/120-kDa molecules are synthesized independently of each other. Four to eight hours after synthesis, the degradation of the 120-kDa molecule to a 105-kDa membrane-associated intermediate begins. This is further processed and appears in the cell supernate as a 90-kDa molecule. Hodgkin's disease-derived, Epstein-Barr virus-transformed cell lines and the acute T cell leukemia line MOLT-4 contain both forms of the Ki-1 antigen, whereas only the 57-kDa intracellular antigen is expressed in U266/B1 myeloma cells, in the Burkitt lymphoma cell lines Raji and Daudi and in acute promyelocytic HL-60 leukemia cells.

Amino Acids↗
PubMed1988

The temporal lobe epilepsy syndrome elucidated through Søren Kierkegaard's authorship and life.

In 1975 American scientists postulated the existence of the temporal lobe epilepsy syndrome. The authors of this paper demonstrate that the Danish philosopher Søren Kierkegaard in "The Book on Adler" 140 years ago has given an eminent phenomenological description of this syndrome. The authors at the same time state the hypothesis that Søren Kierkegaaard's description of Magister Adler actually might be a disguised self portrait.

Denmark↗
PubMed1988

Ego functions in epilepsy.

Two groups of epilepsy patients (28 patients with temporal lobe epilepsy and 15 patients with primary generalized epilepsy) entered a study of personality traits related to epilepsy, based on a modification of Bellak's semistructured interview for assessment of ego strength. Two groups of subjects served as controls: 15 patients with a non-neurological but relapsing disorder, psoriasis, and 15 healthy volunteers. Compared with the group of healthy volunteers, a decreased adaptive level of ego functioning was found in the epilepsy groups, regardless of seizure types and EEG findings, and, to a lesser extent, compared with the psoriasis group. Areas of ego functioning most affected were "reality testing", "cognitive functioning", "integrative functioning" and "regulation and control of drives". Patients with more than one type of seizure were the most affected, as were patients who were younger than 15 years when the disease began. The number of anticonvulsants administered did not influence the results. No difference on adaptive level of ego functioning was found between the group with primary generalized epilepsy and the group with temporal lobe epilepsy. Similarly, the temporal lobe epilepsy group with predominantly right-sided and left-sided EEG changes, respectively, showed similar adaptive levels of ego functioning.

Adult↗
PubMed1987

Biochemical characterization and biosynthesis of the Ki-1 antigen in Hodgkin-derived and virus-transformed human B and T lymphoid cell lines.

The Hodgkin-associated Ki-1 antigen was analyzed in different cell lines. In Hodgkin analogous L428 cells, biosynthetically labeled with radioactive amino acids, the Ki-1 antibody precipitated three glycoproteins with 90, 105, and 120 kDa, respectively. Surface-labeling revealed that the two larger components were membrane-associated forms of the Ki-1 antigen, although the 90-kDa molecule was shown in pulse-chase experiments to be the precursor of the 105- and 120-kDa forms. All three forms of the Ki-1 antigen possess a tunicamycin-sensitive 6-kDa N-linked carbohydrate moiety. O-Linked oligosaccharides could not be detected. Thus, the differences in m.w. are probably not due to glycosylation. The ionophore monensin prevented the appearance of the membrane-associated molecules, which demonstrated that they are assembled between the transcompartment of the Golgi complex and their insertion into the cell membrane. The 90-kDa precursor molecule cannot be generated by disulfide reduction from the two larger forms. After internal labeling with P-32, only the 105- and 120-kDa bands became visible, indicating that the Ki-1 molecule is phosphorylated after its processing into the two larger membrane-associated forms. Analysis of the Ki-1 antigens from other cell lines demonstrated that after external labeling of two other Hodgkin-derived cell lines, six Epstein-Barr virus lymphoblastoid cell lines and one human T leukemia virus I-positive T cell line, both the 105- and the 120-kDa membrane molecules could be detected, regardless of the presence or type of virus integrated.

Antigens, Neoplasm↗