Biomedical subjects
Publications and source records attributed to J Jansen.
A novel way of representing 1D MAS spinning sideband spectra in a 2D-resolved fashion is explained. The method is illustrated with 2H MAS data of deuterated polycarbonate. From the resulting 2D spectrum, the isotropic shifts can be identified on one axis and the rotary echo decay spectra along the other axis.
Sumatriptan, a novel selective 5-hydroxytryptamine1d (5-HT1d) receptor agonist, which is highly effective in the acute treatment of migraine attacks, blocks dural neurogenic plasma extravasation and constricts cranial blood vessels in animal experiments. We measured intra- and extracranial blood flow velocities (BFV) with a transcranial Doppler device in 67 patients during a spontaneous migraine attack, before and after treatment with 3 mg or 6 mg subcutaneous sumatriptan or placebo. Sumatriptan, but not placebo, significantly increased BFV (cm/sec) in the internal carotid and middle cerebral arteries on both sides, without detectably changing the BFV in the common and external carotid arteries. The rise in BFV increased with the dose of sumatriptan, parallel to an increase in proportion of patients improved. There were no significant changes in heart rate, blood pressure, or respiratory frequency after treatment with sumatriptan. The increase in BFV probably reflects vasoconstriction of the large basal intracranial arteries, which may be a mechanism for the antimigraine action of sumatriptan.
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A 28 year old woman with a previous history of labile hypertension, migraine and transitory cerebral ischemia was admitted with cerebral infarction. One month later she developed livedo reticularis and amaurosis fugax, which led to the diagnosis of Sneddon's disease (livedo reticularis, labile hypertension and neurological symptoms) and the anticardiolipin antibody (ACA) syndrome. Treatment with prednisone and phenprocoumon resulted in lowering of ACA-titers, but the symptoms did not subside until acetylsalicylic acid was added.
Antiphospholipid antibodies (APA) are acquired, circulating immunoglobulins connected with thrombo-embolic diseases occurring within all organ systems. Whether the antibodies are of pathogenetic relevance for the development of thrombo-embolic states is unresolved. All materials are limited and have yielded contradictory results with regard to important aspects. An increased APTT or PTT does not increase the risk of bleeding in patients with LA, unless abnormalities in the coagulation process are present, e.g. thrombocytopenia or hypoprothrombinaemia. Many questions are unanswered: Should APA be treated in asymptomatic patients? Should patients with APA and relevant symptoms be treated? If so, which treatment should be chosen? And how long should the treatment continue? Are APA of pathogenetic importance or are they markers for another mechanism that causes an immunocoagulopathy? How can it be explained that so many persons produce autoantibodies without becoming seriously ill? In order to clarify the significance of APA it is necessary to standardize tests and to perform extensive, prospective studies, where variations of ACA titres are analysed. Until results from such studies are available, APA should be looked for in patients with recurring arterial or venous thrombosis and in patients with recurring spontaneous abortion with reference to anticoagulant and anti-platelet aggregation therapy if IgG-ACA are elevated over prolonged periods.
Poor upper extremity function is often recorded in meningomyelocele patients. Only 2 of the 25 patients we assessed, 5 to 19 years old, showed normal upper extremity function in the clinical neurological examination and a timed hand function test simulating daily activities. Slow performance with unsystematic variability was typical. Poor hand function correlated strongly with hydrocephalus. A trend towards better performance with increasing age may indicate that the difficulties are overcome in some patients. While patients without hydrocephalus showed a near-normal distribution in the seven subtests, patients with hydrocephalus needed more time than normal children. Patients with shunt-treated hydrocephalus did not cope as well as patients without a shunt. Mean age in the three groups differed and may partly explain the differences.
Serum anti-gliadin antibodies (AGAs) of the IgG and IgA isotypes were determined in 17 children (mean age of 5.6 years) by means of an enzyme-linked immunosorbent assay (ELISA). All children were suspected of celiac disease. They had been on dietary treatment for at least 10 months before they were challenged with gluten. Based on jejunal biopsy findings, 10 of the 17 children had to be considered positive. The sensitivity of the measurement of AGA at 6 weeks after gluten challenge was found to be 90% for IgG, 100% for IgA, and 100% for IgG/IgA combined. The specificity for IgG, IgA, and the IgG/IgA combination was 100, 71, and 100%, respectively. Twelve weeks after gluten challenge, the sensitivity as well as the specificity of AGA determination for IgG, IgA, and IgG/IgA were 100%. It is concluded that testing both IgG AGA and IgA AGA in children suspected of celiac disease is valuable in monitoring the course of the diagnostic provocation protocol and that jejunal biopsies can be abolished. This inexpensive tool can be useful in reducing the number of intestinal biopsies.
The aim of this new three-leaflet valve development was to design a leaflet with minimum membrane stresses during performance. This is achieved by manufacturing the valve leaflets shaped almost flat in a medium opening position. Thus, the leaflets have two stable positions, one with maximum opening area and the other with favorable stress distribution in the closed position. The transition between the two end positions is achieved through a two-dimensional rolling motion without buckling and with minimum membrane stresses (bulge forces). The manufacturing technique is dip-coating in polyurethane. Hydrodynamic evaluation of the J-3 valve in steady and pulsatile flow showed minimum pressure drop compared to other commercially available valves. Laser-Doppler-anemometry studies indicated very low shear stresses in the flow field downstream of the valve. In durability tests prototypes have reached lifetimes of up to 17 years. In conclusion, the J-3 valve shows superior hydrodynamic performance thereby reducing potential thrombus formation. Minimization of stresses within the valve leaflets through design could reduce calcification.
According to the relevant psychological and psychiatric literature, depersonalization and déjà vu experiences are usually viewed as symptoms of severe psychiatric or neurological disorders, especially in schizophrenia, depression and epilepsy. Studies of these phenomena in non-clinical populations are rate. In this article we present the results of several epidemiological investigations. On the basis of survey and interview research, quantitative and qualitative aspects of both phenomena were assessed, as well as the relations with personality variables like emotionality. The results indicate prevalence rates up to 80 percent in non-clinical populations. Based on epidemiological considerations, the question of differentiation between clinical and non-clinical forms of depersonalization and déjà vu is discussed.
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The connections between the epidemiology of trichostrongylosis in cattle and sheep and immunological phenomena are discussed. It is concluded that the build-up and the reduction of immunity greatly determine the epidemiology of trichostrongylosis. Regulation of immunity and the development of vaccines produce more questions than good prospects for the time being.
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Two somatomedin-like peptides were extracted from Cohn fraction IV of human plasma and brought to homogeneity: one focused at pH 7.8 and the other at pH less than 5.6. Each consisted of two peptide chains interlinked by disulphide bonds. The basic peptide was identical to insulin-like growth factor I (IGF-I) and had a single cleavage in the C-domain before Arg37 [IGF-I(Arg36cl)]. The acid peptide showed identity with IGF-II, with a cleavage in the B-domain before Arg30 [IGF-II(Ser29cl)]. The effects of these cleavages on the characteristics of binding to type I and type II receptor sites, to binding proteins and to antibodies was studied. Binding of IGF-I(Arg36cl) to antibodies directed against the B-domain or against the AD-domain of IGF-I was the same as IGF-I binding. Thus the cleavage does not influence these antigenic sites. In contrast, binding of IGF-I(Arg36cl) to the type I receptor on human and bovine placental cell membranes was markedly decreased compared with IGF-I binding. Binding to the insulin receptor on human placental cell membranes was slightly diminished, whereas the interaction with specific type II receptors on bovine placental cell membranes was unaffected. There was only a minor influence of the cleavage on the region involved in binding to binding proteins. The cleavage in IGF-II(Ser29cl) diminished binding to antibodies directed against the C-domain of IGF-II, compared with binding of IGF-II itself. Binding to receptors (type I and type II) was changed less profoundly. With 125I-labelled IGF-II(Ser29cl), less insulin was needed in order to obtain 50% displacement of the tracer compared with displacement of 125I-labelled IGF-II. The cleaved form of IGF-II probably has a greater affinity towards the common receptor population than does native IGF-II. Binding to binding proteins was not affected by the cleavage in IGF-II.
Using recent descriptions of Dictyocaulus species, all samples of lungworms in cattle were identified as D. viviparus, and all samples from roe deer, red deer and reindeer being identified as D. eckerti by the present authors. Although cross infections between cattle and cervids are reported in the literature, these are not readily established. Because of the different species and the small likelihood of cross infections cattle and cervids are not regarded as serious sources of lungworm infections for each other. As the description of D. noerneri is based on very scanty information and it is not entirely impossible that it could have been D. viviparus, it is regarded as a species inquirenda. The correct name of the large lungworm of cervids is D. eckerti.
The natural killer activity and phenotypic properties of six different subpopulations of normal human peripheral blood lymphocytes obtained by four-color immunofluorescence cell sorting were examined. Phycoerythrin-conjugated CD16 and CD56 were used simultaneously to identify (CD16 + CD56+) NK cells. The cells most effective in mediating NK cytolysis against K562 target cells were CD3-(16 + 56+)57 -8+. Although most of the K562 killing was found in the CD3-(16 + 56 +) groups of cells, a substantial degree of NK activity was detected in the CD3+(16 + 56 +) subpopulations of some individuals. The level of expression of CD57 and CD8 was significantly higher on CD3+(16 + 56 +) than on CD3-(16 + 56 +) cells.
80-90% of individuals suffering from aneurysmal bone cyst (ABC) are children or adolescents. Primary ABC is a non-neoplastic lesion. Diagnostic assessment and detection of recurrence demands repeated plain x-rays or CT scans. These repeated radiographic examinations expose these young patients to large doses of ionizing radiation. Magnetic resonance imaging (MRI) is found to be an effective and reliable noninvasive technique for the diagnosis and follow-up controls of ABC.
Responses to a single or repeated infection with 7000 infective larvae of Haemonchus contortus were studied in an experiment using a total of 106 3-month-old lambs with AA, AB or BB haemoglobin (Hb) genotypes. Results were assessed by faecal egg counts, adult worm counts, haematocrit values, haemoglobin concentrations, total serum protein and serum antibody IgG1 and IgA ELISA titres. None of these parameters showed a strong relationship to the Hb type. The prevalence of low responder (greater than 500 worms) and of high responder (less than 50 worms) animals in groups AA, AB and BB Hb types was 3.8 and 34.6, 20.6 and 35.2, 28.1 and 43.7%, respectively, suggesting that the responsiveness to nematode infection is under the control of gene(s) not closely linked with those determining the Hb genotype. Worm counts of a primary infection are more subject to variation than those of a secondary infection. There is a strong relationship between adult worm counts and faecal egg counts taken close to the time of slaughter. In living animals low and high responder discrimination can be based on individual faecal egg counts around 50 days after a secondary infection. Haematocrit values proved to be of little value in the low and high responder selection. In this regard neither Hb concentration nor total serum protein values are of practical significance. In 3-month-old lambs primary infection induced partial immunity which could prevent the establishment of a part of the secondary infection, irrespective of the presence or absence of the primary worm population. The development of immunity was not associated with an increase of serum IgG1 and IgA antibody levels. Specific antibody production was not influenced by Hb types. Mean antibody levels of low responder lambs showed no difference from those of high responders. Thus, serum IgG1 and IgA levels are of no predictive value in identifying lambs which are genetically resistant to Haemonchus infection.