[Initiating patients on home mechanical ventilation]. / Instellen van patiënten op chronische thuisbeademing.

More and more patients with chronic respiratory insufficiency are eligible for home mechanical ventilation. As a result, medical doctors are increasingly confronted with said patients. The treatment goal of this supporting therapy is to improve quality of life and possibly life extension. Centres for home mechanical ventilation decide on the indication, whereas the clinical setup of the ventilator takes place in a hospital setting. Staff in the Dutch Gelderse Vallei hospital have been initiating - both non-invasive and invasive - home mechanical ventilation for various patient groups for the last 4 years. This is a labour-intensive process during which numerous issues can occur. Experience and expertise is necessary for a successful process. A multidisciplinary approach and accessible consultation between stakeholders is of great importance when setting up home mechanical ventilation for these patients.

[Prenatal study of trisomy 21: triple test more efficient than age criterion]. / Prenataal onderzoek op trisomie 21: tripletest efficiënter dan leeftijdscriterium.

OBJECTIVE: To compare the results of selection of gravidae for trisomy 21 testing on the basis of age or of the triple test. DESIGN: Theoretical evaluation. METHOD: Demographic statistical data for the years 1980, 1985, 1990 and 1994 and the age-specific risk were used to calculate the expected number of children to be born with trisomy 21. Also calculated were the size of the risk groups, the number of children with trisomy 21 to be detected early, the iatrogenic loss of pregnancy and the number of invasive tests to be performed in order to detect one child with trisomy 21 with either selection method. RESULTS: Shifting of pregnancy to women with a mean older age results in a increase of the risk group as determined by age. It will also result in an increase of the number of iatrogenic losses of pregnancy. Selection of the risk group by the triple test will not result in these increases. The risk group, as determined by the triple test, includes about 60 per cent of the women pregnant of a child with trisomy 21; that determined by age 23 to 30 per cent. The number of invasive tests to be performed for the detection of one child with trisomy 21 is significantly smaller in case of selection by the triple test. CONCLUSION: By application of the triple test less pregnant women have to be further examined and more cases of trisomy 21 are detected, than by application of the age criterium.

The detection of anisochrony in monaural and interaural sound sequences.

Nakao and Axelrod (1976) and van Noorden (1975) showed that the threshold for discriminating an anisochronous duple rhythm (a series of clicks with a temporal offset on every other one) from an isochronous rhythm (no offset) is poorer when the clicks are presented alternately to the two ears than when they are presented to the same ears. Van Noorden reported that the difference between the thresholds in the alternating and nonalternating conditions varied with the tempo of the sequence. Nakao and Axelrod found invariance of this threshold difference with sequence speed. According to our quantification of temporal processing of interaural sequences, the latter result should be expected. We carried out five psychophysical experiments to establish interaural and monaural discrimination between isochronous and anisochronous rhythms. Across experiments, base time intervals of 60-720 msec were spanned. The main result was that we replicated the poorer discrimination for interaural sequences. This deterioration in discrimination was the same for all sequence speeds. It was also the case that the thresholds were almost constant up to a sound repetition rate of about 3 per second, but increased linearly with slower rates. This result supports evidence in the literature that temporal processing of sequences faster than about 3-4 sounds per second differs from temporal processing of slower sequences.

Free space iron pools in roots: generation and mobilization.

A rapid and simple method for the determination of a ferric iron pool in the free space of roots is described. Formation of this pool depended on the source of iron in the nutrient solution. During growth in water culture at pH 5 to 6 with Fe-ethylenediaminetetraacetate, a free space pool of 500 to 1000 nanomoles Fe per gram fresh weight was formed in the roots of bean (Phaseolus vulgaris L. var. Prélude), maize (Zea mays L. var. Capella), and chlorophytum (Chlorophytum comosum [Thunb.] Jacques). No significant pool (less than 100 nanomoles per gram fresh weight) was formed with ferrioxamine. Upon impending Fe deficiency, bean and chlorophytum were able to mobilize this pool. Fe-deficient bean plants mobilized iron from the free space iron pool of another plant in the same vessel.

Immunofluorescence studies with 4-acetamido-4'-isothiocyanato stilbene-2,2'-disulphonic acid (SITS).

The application of the fluorochrome 4-acetamido-4'-isothiocyanato stilbene-2,2'-disulphonic acid (SITS) in immunofluorescence was studied. The optimal excitation wave length is 350 nm, and optimal fluorescence is obtained at 420 nm. After purification of the commercial compound, conjugation is performed in a strong buffer at pH 9.0-9.5. SITS conjugates were very satisfactory for immunofluorescence studies of the cytoplasmic antigens of cell preparations, but their blue emission was difficult to distinguish from autofluorescence in sections of human tissues. Good results with immunofluorescence on membrane bound antigens were obtained by using an ultra-violet laser beam as light source. SITS can be used simultaneously with FITC and TRITC conjugates thus making it possible to show three antigens in one preparation.

Kappa-chain deficiency. An immunoglobulin disorder.

Since kappa-chain deficiency is an unusual condition, we studied the clinical and laboratory findings in a patient with this deficiency. The patient had cystic fibrosis with concurrent malabsorption, diabetes mellitus and IgA deficiency. The serum levels of IgM and IgG were 0.85 and 7.22 mg per milliliter, respectively. Kappa type IgM and IgG was not present in serum and external secretions; gamma, mu and lambda chains were probably polyclonal in character. Antibodies against kappa chains were not detected in either the patient or the mother. Plasma cells containing kappa-type immunoglobulins were absent in jejunum samples and bone marrow; kappa-chainbearing B lymphocytes could not be detected in blood and bone marrow. The serum of one of the patient's sisters contained trace amounts of kappa-type immunoglobulins. The patient displays a complete absence of kappa-type immunoglobulins, probably owing to a genetic defect.

Light chain type ratio of IgA-producing cells in human jejunal biopsies.

As part of an investigation on a possible relationship between the serum IgA and the immunoglobulins synthesized by the plasma cells in the intestinal mucosa, immunoglobulin-producing cells in human jejunal biopsies were characterized by class and type of intracellular immunoglobulins. In biopsy Specimens from 22 patients, with various diagnoses except multiple myeloma, the average percentage of IgA-producing cells was 83 percent, that of IgG-producing cells 5 percent and that of IgM-producing cells 12 percent, with a wide range for individual patients. For the IgA-producing cells the kappa/lambda ratio was determined and the average ratio was found to be 63 : 37, within a very limited range for individual patients. There was no correlation between the relative number of IgA-producing cells in the biopsy specimens and the IgA concentration in the serum. Additionally biopsy specimens from 3 patients with a monoclonal immunoglobulin-A component in their serum were studied. In one of those there was a remarkable shift in the kappa/lambda ratio, indicating that the light chain distribution of the intestinal IgA plasma cells was affected by the lympho-proliferative process.