Determination of 232Th by neutron activation analysis using isotope-related ki factors.

Neutron activation analysis was applied to determine the 232Th activity in different matrices. Since in nature thorium consists of almost 100% of the long-lived 232Th, the instrumental trace element analysis method of neutron activation analysis can be applied to determine the thorium content in a sample. which can then be converted into the corresponding specitic activity. For the analysis about 100 mg of the sample was irradiated at a thermal neutron flux of phi(th) = 8 x 10(13) n.cm(-2) x s(-1). After irradiation the activity of the indicator nuclid 232Pa--produced by the (n,gamma) reaction--was measured by gamma spectrometry. The content of thorium was calculated using the activation equation and the isotope-related ki constant. Finally, the concentration of thorium in the sample was converted into the specific activity. The activities of 232Th measured by applying neutron activation analysis in different samples were compared with the results found by a spectrometry and gamma spectrometry for the daughter nuclides 228Ac and 224Ra.

[Clinical thinking and decision making in practice. A student with sudden headache]. / Klinisch denken en beslissen in de praktijk. Een student met plotselinge hoofdpijn.

A previously healthy man aged 18 years suddenly developed a severe headache, followed by nausea, vomiting, fever. During the following weeks a left-sided hemiparesis developed. CT of the brain revealed a pansinusitis and a frontal epidural empyema. A few days after surgical drainage his condition deteriorated and subsequent CT showed a right-sided subdural empyema. This was surgically evacuated and followed by long-term high-dose intravenous antibiotic therapy. The patient made a complete recovery. A sudden severe headache can be caused by an intracranial infection and intracranial pus collections can occur in the subdural as well as in the epidural space. Epidural empyema is a limited disease with relatively mild symptoms and a favourable prognosis, whereas subdural empyema may rapidly spread and cause severe disease with a poor prognosis. Quick antibiotic treatment and surgical drainage are required.

Management of infantile subglottic hemangioma: laser vaporization, submucous resection, intubation, or intralesional steroids?

The infantile subglottic hemangioma can be treated in various ways. The results of the treatment used in the Sophia Children's Hospital, intralesional steroids and intubation (IS + I), are discussed and compared with the results of other current treatment methods: CO2 laser vaporization, submucous resection and intubation alone. A total of 18 infants were treated for subglottic hemangioma in our hospital: ten with IS + I alone, five were first treated with systemic therapy and later with IS + I alone and three with various therapies. IS + I was effective in 14 of the 15 patients, one patient was lost from follow up. The remaining three infants were treated with (combinations of) various therapies, because IS + I failed or was not tried. Two patients were finally cured, one still has a tracheotomy. Of other current therapies, CO2 laser vaporization is reported to be effective. In all 30% of the infants treated in Boston Children's Hospital with CO2 laser needed a tracheotomy. Moreover subglottic stenosis is a serious complication. Submucous resection is often successful. It may be complicated by subglottic stenosis and in some cases, depending on the localization of the hemangioma, it may be contraindicated. Intubation alone is less effective than intubation combined with intralesional steroids. Management of subglottic hemangioma in Sophia Children's Hospital is primarily intralesional steroids and intubation and secondarily submucous resection or tracheotomy. CO2 laser vaporization is seldom applied because of the risk of subglottic stenosis.

[Immunohistochemical analysis of graft rejection in formalin fixed kidney biopsies]. / Immunhistochemische Analyse von Transplantatabstossungsreaktionen an formalinfixierten Nierenbiopsien.

One hundred and five formalin fixed renal allograft biopsies with a graft survival of more than 12 months have been examined by histological and immunohistochemical methods. 51 cases of vascular and 41 cases of tubulointerstitial allograft rejections were diagnosed by conventional light microscopy. 13 cases showed a combined type of rejection. The vascular and the interstitial type contain on average 64 respectively 79 CD 45 positive cells/mm2 surface of section. A mean of 70 cells/mm2 has been calculated for the combined type of rejection. The corresponding mean values of MT 1 positive T-lymphocytes are 46 in the vascular type, 52 in the combined type and 60 cells/mm2 in the tubulointerstitial type of allograft rejection. Apparently because of the great ranges there are no statistically significant differences between the observations in the different types of rejection. His equal for the concentration of Mac 387 positive macrophages and as well for the content of L26 positive B-lymphocytes in the different types of rejection. The concentrations of HLA-DR expressing cells in the interstitium are determined with a monoclonal anti-HLA-DR antibody, which detects a fixation resistant epitope of the DR-molecule. There is an average of DR positive cells/mm2 of 79 in vascular and 107 in interstitial rejection. The combined type of rejection contains 86 cell/mm2 on average, so that there is a statistically significant positive correlation, if you will order the observations in sequence of vascular, combined and interstitial type of rejection. In this case the observations of interstitial and vascular rejections differ statistically significant as well.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell fusion by simulated atmospheric discharges: further support for the hypothesis of involvement of electrofusion in evolution.

Electrofusion of mesophyll cell protoplasts of Avena sativa was induced by simulated atmospheric discharges. It is shown both experimentally and theoretically that the potential differences which occur at quite long distances from the point of lightning stroke are large enough to induce fusion. Besides electromagnetic waves which are emitted during lightning (G. Küppers and U. Zimmermann, FEBS Lett. 164, 323 (1983] cell fusion may have also occurred directly by means of the voltage built-up on the earth during evolution in response to a lightning stroke.

Rotation of cells and ion exchange beads in the MHz-frequency range.

Whereas human red blood cells and protoplasts of leaves of Avena sativa show rotation only at discrete frequencies in the kHz-range of a linear alternating electric field, rotation of these cells is observed at practically every frequency in the MHz range (15 to 200 MHz). The cell rotation in the MHz-range can be explained in terms of field induced polarisation and orientation of permanent dipoles within the membrane and the cell. This interpretation is supported by the finding that Chelex beads (polystyrene cross-linked with divinylbenzene and coupled to iminodiacetic acid) do exhibit rotation in the MHz-range, but not in the kHz-range. It is most interesting that the Cu2+- and Ca2+-forms of the Chelex beads show a shift in the rotation frequency spectrum in addition to an increase in the magnitude of the rotation speed with respect to the Na+-form. At frequencies in the MHz-range at which rotation of the Chelex beads is not observed, formation of chains of beads from the electrodes occurs instead. This is due to positive polarisation of the beads leading to positive dielectrophoresis. The results support the view that rotation needs negative polarisability which is determined by the functional groups.

The hydraulic conductivity as a criterion for the membrane integrity of protoplasts fused by an electric field pulse.

The hydraulic conductivity of the membrane, Lp, of fused plant protoplasts was measured and compared to that for unfused cells, in order to identify possible changes in membrane properties resulting from the fusion process. Fusion was achieved by an electric field pulse which induced breakdown in the membranes of protoplasts in close contact. Close membrane contact was established by dielectrophoresis. In some experiments pronase was added during field application; pronase stabilizes protoplasts against high field pulses and long exposure times to the field. The Lp-values were obtained from the shrinking and swelling kinetics in response to osmotic stress. The Lp-values of fused mesophyll cell protoplasts of Avena sativa L. and of mesophyll and guard cell protoplasts of Vicia faba L. were found to be 1.9±0.9·10(-6), 3.2±2.2·10(-6), and 0.8±0.7·10(-6) cm·bar(-1)·s(-1), respectively. Within the limits of error, no changes in the Lp-values of fused protoplasts could be detected in comparison to unfused protoplasts. The Lp-values are in the range of those reported for walled cells of higher plants, as revealed by the pressure probe.

On nickel contents in urine and hair in a case of exposure to nickel carbonyl.

In an accidental case of exposure to nickel carbonyl with a few persons weak symptoms of illness were observed. Rapid and simple methods of flameless atomic absorption spectroscopy were applied for the determination of nickel in urinary samples and in sections of bundled hairs. The measurements showed in some cases remarkable increased Ni values well above normal levels. The data obtained will be amply discussed and can be used in part for a rough estimation of the biological half life of inhaled Ni.