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Biomedical subjects

C J Brandt

Publications and source records attributed to C J Brandt.

17 recordsLinked to original sources
PubMed2001

[Questions as evident key to knowledge: teaching medical students evidence-based medicine].

INTRODUCTION: In Denmark, as in other countries, there is an increasing focus on evidence-based medicine (EBM) as a necessary tool for using modern sources of information, but until now EBM training has not been incorporated in our undergraduate curriculum. MATERIAL AND METHODS: This course is given in the ninth semester (out of 13) and the subject matter is clinical biochemistry. The course consists of seven (one-hour) lectures over three weeks. First, the EBM method is introduced, then the students split up into small groups, choose their own diagnostic problem, and carry out a structured search. The search leads to the choice of a scientific article, which is subsequently presented to and discussed by all the students. We asked about their opinion of the course by questionnaire. RESULTS: The answers to the questionnaire confirmed that the students have improved their ability to read and assess scientific articles and to seek information, and it has stimulated them to understand concepts instead of memorising details. DISCUSSION: Although the assessment of this course was positive, it can no doubt be improved and further developed. In our opinion the use of EBM should not be confined to one course. The medical students should be introduced to EBM at an early stage, thereby abling them to practice it throughout their training.

Biochemistry↗
PubMed2001

Blood sampling from the retro-orbital plexus, the saphenous vein and the tail vein in rats: comparative effects on selected behavioural and blood variables.

We compared the behaviours of rats, and measured various blood parameters, after three blood sampling techniques: orbital puncture while they were under diethyl-ether anaesthesia, blood collection by tail vein puncture under O2-N2O-halothane anaesthesia and puncture of the saphenous vein without anaesthesia. Twelve rats were subjected to the three treatments according to a Latin square design. After each treatment, the behaviour of the rats was automatically monitored using the so-called LABORAS method, which discriminates between grooming, locomotion and inactivity in rats. Based on excitation scores and urine production, it was found that induction of diethyl-ether anaesthesia combined with orbital puncture caused more distress than did the other two blood sampling techniques. The three techniques had no differential effects on the behaviours of grooming, locomotion and inactivity. Collecting 0.5 ml of blood by orbital puncture was +/-7 times faster than doing so by saphenous vein puncture and +/- 15 times faster than collecting blood by tail vein puncture while the rats were under O2-N2O-halothane anaesthesia. The levels of some haematological and plasma variables differed significantly between the three blood collection techniques. These observations may help to select the most appropriate technique of blood sampling with respect to anticipated discomfort in the animals.

Anesthesia, Inhalation↗
PubMed2000

Climate quality and climate consensus as mediators of the relationship between organizational antecedents and outcomes.

Research has shown that climate quality (average climate ratings) is related to organizational antecedents and outcomes, but researchers have yet to examine climate consensus (the variance of climate ratings). Similarly, studies have investigated typical behavior (members' average performance), but have neglected behavioral similarity (within-group variance). Data from 1,196 members in 180 organizations were used to test relationships of climate quality and consensus with organizational antecedents and outcomes. Climate quality and consensus both had significant correlations with organizational antecedents and outcomes, but climate consensus did not contribute a significant increment to the prediction of organizational outcomes. Finally, quality mediated many relationships between organizational antecedents and outcomes.

Decision Making↗
PubMed1998

[Choledocholithiasis. Endoscopic treatment of 416 consecutive patients].

Endoscopic extraction of calculi in the common bile duct has been the treatment of choice for many years. According to international standards a stone-free common bile duct should be achieved in at least 90% of the patients and with an overall complication rate below 20%. We reviewed records of 416 patients who underwent ERC for common bile duct stones between January 1990 and January 1995. The overall success rate of achieving a common bile duct free of stones was 89.0%, and in 94.7% of the patients endoscopic treatment was definitive. The overall complication rate was 9.6% and the 30-day mortality rate was 2.2%. Our study showed that with a medical staff of four to six persons (of which two were trainees), approximately 450 ERCP-examinations per year and with a catchment area of half a million inhabitants (Funen County), it was possible to achieve acceptable results.

Adult↗
PubMed1998

Glutathione is present in reproductive tract secretions and improves development of mouse embryos after chemically induced glutathione depletion.

We investigated the hypothesis that reduced glutathione (GSH) is present in secretions of the female reproductive tract and that this extracellular GSH may protect preimplantation mouse embryos after intracellular GSH depletion. The cleavage-stage mouse embryo cannot synthesize GSH de novo and is unable to recover from glutathione depletion in vitro. Analysis of GSH and total protein of oviduct flushings, quantified by HPLC and the Bradford method, respectively, revealed 51 nmol GSH per mg total protein. Embryos were treated with 60 microM diethyl maleate (DEM) to deplete cellular GSH. When cultured with 1 mM GSH, these embryos exhibited improved development compared to those cultured in control medium (96% vs. 87% morula [p < 0.05], 78% vs. 75% blastocyst, 58% vs. 54% expanded blastocyst, 21% vs. 17% initiating hatching blastocyst). However, intracellular GSH content of embryos was not significantly increased by the culture of DEM-treated embryos in medium containing GSH for 16, 40, or 64 h of incubation, suggesting that the embryo is not capable of taking up intact GSH. Furthermore, addition of buthionine sulfoximine (which inhibits synthesis of GSH) or acivicin (which inhibits breakdown of GSH at the membrane) to culture medium blocked the improvement in development. These data suggest that GSH in reproductive tract fluid may help protect preimplantation embryos from the adverse effects of toxicant-induced and endogenous depletion of embryonic GSH.

Animals↗
PubMed1998

Orbital sinus blood sampling in rats as performed by different animal technicians: the influence of technique and expertise.

In this study the influence of orbital sinus blood sampling on clinical signs was studied within the framework of various nutritional experiments. In order to assess the clinical signs in a random design, the rats were punctured in either the left or the right orbit. Thus, the effect of puncture within rats could be determined by comparing the left and right eye. Four animal technicians punctured a total of 303 rats, using different techniques. Orbital sinus blood sampling caused clinically visible alterations. The type, frequency and prognosis of the alterations differed with the person performing the puncture. Two experienced animal technicians were able to perform the technique without causing a statistically significant increase in alterations in punctured orbits. One less experienced animal technician caused severe abnormalities. The use of either a Pasteur pipette or a haematocrit capillary did not necessarily produce different results. Neither did puncturing the lateral vs the medial canthus of the orbit. By not applying chloramphenicol eye ointment in the conjunctival sac after puncture, the number of abnormalities in 'ocular discharge' and 'corneal alterations' in the punctured orbits was significantly decreased. Four punctures in the same orbit with 14-day intervals by a skilled animal technician did not cause a significant increase in abnormalities.

Animals↗
PubMed1997

[The diagnosis of "smoker's lung" encourages smoking cessation].

In a controlled randomised trial we analysed whether the use of the term "smoker's lung" (Danish: "rygerlunger") instead of chronic bronchitis when talking to patients with chronic obstructive lung disease (COLD) changed their smoking habits. Fifty-six smoking patients with COLD were allocated to either intervention (n = 25) or control groups (n = 31). In the intervention group the lung disease was designated smoker's lung in all communication with patients about their illness and in the control group traditional terminology was used. All patients were given the same medical treatment and the same encouragement to stop smoking. One week after discharge 57% had stopped smoking in the smoker's lung group vs 26% in the control group (p = 0.028), at three months 50% vs 19% (p = 0.027) and at one year 40% vs 20% (p = 0.148). Referring directly to the cause of a self-inflicted illness may be an effective way of discouraging risk behaviour, at negligible cost.

Adult↗
PubMed1991

Bone growth and remodeling after distraction epiphysiolysis of the proximal tibia of the rabbit. Effect of electromagnetic stimulation.

The effect of pulsed electromagnetic stimulation on bone formation was tested in a lower-limb-lengthening model in the rabbit. Limb lengthening was performed by distraction epiphysiolysis. A specially designed external distraction device allowed 10 mm of lengthening of the tibia. Coils to generate a pulsed electromagnetic field were clipped onto the distractor. Stimulation started after a distraction period of three weeks and was continuous for 18 weeks. A control group received the same treatment without stimulation. Bone formation in the elongated zone was evaluated by computed tomography, scintigraphy, and histology. Bone healing involved accretion of callus followed by a process of remodeling, resulting in the formation of a solid cortex. The formation of a diaphysislike structure at the original site of the metaphysis progressed from the distal end of the elongated zone upward. Electromagnetic stimulation had no effect on the rate or extent of bone formation and remodeling.

Animals↗
PubMed1987

The use of computed tomography to quantitate bone formation after distraction epiphysiolysis in the rabbit.

A study of limb lengthening by distraction epiphysiolysis in the rabbit tibia is presented. For this purpose a special external distraction device was developed, which allowed 10 mm lengthening of the leg. Bone formation in the distraction zone was quantified by means of computed tomography. Cross-sectional scan planes at 1.5 mm separation revealed bone formation proceeding for several weeks after the end of the distraction period. A period of bone remodeling followed, resulting in the formation of a solid cortical structure, similar to the diaphysis, in the distraction zone.

Animals↗
PubMed1987

Implantation of cultured thymic fragments in congenitally athymic (nude) rats. Influx of lymphocytes and dendritic cells.

We studied the early events in athymic immunoincompetent rats after implantation with cultured thymic fragments (CTF) under the kidney capsule, with special emphasis on the settlement of lymphocytes and non-lymphoid RT1 class II elements. At 2 weeks after grafting, tissue under the kidney capsule comprises strands of keratin-positive epithelial cells from the graft, without immigrant cells. At 3 weeks, the CTF graft is populated with lymphocytes and with non-lymphoid RT1 class II-positive cells expressing the recipient haplotype (allogeneic combinations). Part of these cells bear determinants recognized by an anti-rat dendritic cell antibody. At 4 weeks the graft exhibits a completely restored thymic architecture. At the periphery, the first indications of T-cell competence generated after CTF implantation are observed 6 weeks after implantation. At 18 weeks, the peripheral thymus-dependent immune system is almost completely developed. This includes in vitro alloreactivity, even to the donor RT1 haplotype of the graft. But skin grafts of the allogeneic CTF donor haplotype are not rejected. Thus, a state of in vivo tolerance is induced under the influence of grafted epithelium, which is not due to a specific deletion of alloreactive cells. We conclude that CTF regain their original thymic architecture between 2 and 4 weeks after implantation in (allogeneic) athymic nude recipients, and that only after this restoration does peripheral thymus-dependent immune competence start to develop.

Animals↗
PubMed1986

Implantation of cultured thymic fragments in congenitally athymic nude rats: ignorance of thymic epithelial haplotype in generation of alloreactivity.

We studied the development of thymus-dependent immunity in congenitally athymic nude rats after implantation of cultured thymic fragments (CTF), particularly the development of in vitro alloreactivity in allogeneic combinations. CTF of DA (RT1a), PVG (RT1c), and RP (RT1p(u,1] origin were implanted in nude rats of WAG (RT1u) origin. In analysis 14 to 18 wk later, all recipients exhibited thymus-dependent immunocompetence assessed by (immuno)-histology of lymphoid organs and responsiveness to in vitro concanavalin A stimulation and in vivo ovalbumin immunization. Control nude animals were unresponsive. Also, in vitro alloreactivity was observed, measured by mixed lymphocyte reaction and cell-mediated lympholysis. The alloresponse to the allogeneic CTF donor haplotype was as to a third party, but that to the recipient was negative. The CTF before implantation were devoid of lymphoid elements and revealed epithelial-like cells as the major component. Cells in CTF showed expression of RT1 class I and class II antigens. CTF at autopsy had the architecture of a normal thymus. In immunohistochemistry using haplotype-specific antibodies, lymphocytes showed RT1u class I expression as in the normal WAG thymus. In the cortex-like area of CTF, stromal cells revealed class I and class II haplotype expression of the donor thymus, but in the medulla-like area, class II haplotype expression was that of the recipient WAG rat. These data indicate that after implantation in nude rats, CTF become populated not only with lymphoid elements, but also with stromal components from the recipient. In induction of thymus-dependent immunity, these acceptor-derived stromal (dendritic) cells may be involved in generation of allospecificity; class I and class II haplotype expression by the donor cortex (epithelial) compartment is ignored in this process.

Animals↗
PubMed1985

In vivo biological effect of allogeneic cultured thymic epithelium on thymus-dependent immunity in athymic nude rats.

We have extended our previous study of induction of T-lymphocyte immunocompetence in athymic nude rats by cultured epithelium (CTE) of syngeneic origin to that by CTE of allogeneic origin. Immune responsiveness (IgG-class antibody and delayed-type hypersensitivity) after ovalbumin immunization is detectable by 4-6 weeks after transplantation. However, the antibody appears at a slower rate when compared with heterozygous immunocompetent littermates. Seven weeks after transplantation phytohaemagglutinin responsiveness of spleen cells is detectable, and in T-dependent areas of lymphoid organs lymphocytes with helper and non-helper T-cell phenotype are present, but at lower levels than those in heterozygous immunocompetent littermates. Levels comparable to that of immunocompetent rats are reached about 20 weeks after transplantation. Since CTE contains thymocytes, control experiments consisted of transplantation with high numbers of allogeneic freshly isolated thymocytes in athymic nude rats. These animals showed IgG-class antibody formation after ovalbumin immunization, but at lower levels than CTE-treated rats, and were almost negative in T-cell immunocompetence assessed in the other assays. We conclude that CTE of allogeneic origin induces T-cell immunocompetence in athymic nude rats to the level of heterozygous immunocompetent littermates. This study adds to the rationale of CTE transplantation applied in treatment of thymic dysfunction.

Animals↗
PubMed1982

Preparation and characterization of the anti-idiotypic properties of rabbit anti-timothy antigen B helper factor and anti-mouse timothy IgE antisera.

with AgB-primed B or T cells and injected into syngeneic X-irradiated recipients. Anti-THF and anti-Eid purified by an AgB-specific T suppressor factor (TSF) affi-gel adsorbent retain their ability to specifically initiate [3H]-thymidine incorporation of AgB-primed T cells. The data indicate that both anti-THF and anti-Eid recognize unique determinants present on AgB-specific T-helper, T-suppressor and B cells, and suggest that the receptors on AgB-specific T and B cells share cross-reactive idiotypic determinants.

Animals↗
PubMed1981

Induction and characterization of suppressor T cells and soluble factors with modified timothy grass pollen AgB.

Previous studies demonstrated that antigen B (AgB), a major antigen of timothy grass pollen, modified by photooxidation (Ox-AgB) does not react with rabbit, human, or mouse antibodies directed against AgB and does not induce antibodies reactive with either native or modified AgB. However, immunization of mice with Ox-AgB in alum induces significant T helper cell activity. In this review, we describe the conditions and kinetics for Ox-AgB induction of T suppressor cells, the secretion of AgB-specific T suppressor factor (TSF), and the partial purification of AgB-specific TSF.

Adsorption↗
PubMed1981

Antigen B-specific helper factor from timothy grass pollen: isolation and partial characterization.

Spleen cells from LAF1 mice primed with photo-oxidized antigen B exhibit helper T-cell activity when assayed in an adoptive transfer system with spleen cells from mice primed with timothy pollen extract and treated with anti-thy 1.2 serum and complement. These helper cells, when placed in culture with antigen B, secrete a soluble antigen B-specific helper factor (THF) that requires the presence of normal spleen cells or cells that do not adhere to nylon wool in order to exhibit T cell-replacing activity. The THF has been partially purified over an immobilized antigen adsorbent. The eluted THF exhibits a mol. wt of 65,000 by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), and contains 5% carbohydrate by weight. The THF is I-Ak-positive and Ig-negative.

Animals↗
PubMed1976

Extracellular and protease-released pullulanases.

The extracellular form of pullulanase (EC 3.2.1.41) from Klebsiella aerogenes has been purified to homogeneity by successive chromatography through diethylaminoethyl-cellulose, Sephadex G-200, and 1,6-diaminohexane-Sepharose. In addition, the cell-bound form of pullulanase has been released by the action of a serine endopeptidase obtained from Pronase and purified to apparent homogeneity. Protease-released pullulanase has a slightly larger molecular weight and a specific activity over twice that of the extracellular protein. The properties of each of these forms of pullulanase have been compared with those reported for the detergent-released form. Each form has different features as examined by amino acid composition, specific activity, molecular weight, or inhibition pattern, which distinguish it from the other pullulanases. It is hypothesized that a single gene product consisting of a single polypeptide chain generates these different enzyme forms after selective cleavages by endogenous or applied proteases.

Amino Acids↗