Biomedical subjects
G Dahl
Publications and source records attributed to G Dahl.
Fusion of neurohypophyseal membranes in vitro.
Freeze cleaving electron microscopy has shown that fusion of isolated secretory vesicles from bovine neurohypophyses was induced by Ca2+ in micromolar concentrations. Mg2+ and Sr2+ were ineffective. Mg2+ inhibited Ca2+-induced fusion. In suspensions containing secretory vesicles as well as sheets of cell membrane, release of vasopressin parallel to intervesicular fusion and fusion of secretory vesicles with sheets of cell membrane was observed after exposure to Ca2+. Mg2+ and Sr2+ were ineffective in replacing Ca2+ as trigger for fusion or vasopressin release. Intervesicular fusion and exocytotic profiles were observed when isolated neurohypophyses or neurosecretosomes were exposed to cold.
[Cardioplegia according to Bretschneider for valve replacement: clinical experiences and electronmicroscopical results (author's transl)].
We report about clinical experiences with the cardioplegia according to Bretschneider combined with deep selective hypothermia of the heart in 44 patients. Before, during and after cardioplegia we made biopsies from the left ventricle of 6 patients for electronmicroscopical examinations. Besides the mitochondrial changes already known we saw a break-down of the nexuses. We discuss the importance if these changes for the action of the cardioplegia. Both changes seemed to be reversible. The clinical results and the immediate and later postoperative follow-up demonstrate, that with the described technique a good myocardial protection can be done. This procedure allows operating with a low risk at a completely arrested and relaxed heart until 130 minutes.
Peripheral blood lymphocyte populations in influenza patients.
The peripheral blood lymphocyte populations were determined in 10 patients during the acute phase of influenza and 6-8 weeks after recovery. The percentage of T-lymphocytes, demonstrated by their binding sheep erythrocytes non-specifically (E-rosette forming cells), was decreased during influenza. A relative and absolute increase of non-T-lymphocytes could be shown by the determination on these cells of receptors for activiated C'3 (EAC-rosette forming cells).
Effect of phase transition on the distribution of membrane-associated particles in microsomes.
(1) Rat liver microsomes were studied by freeze-fracture electron microscopy. The distribution of membrane-associated particles indicated the right-side-out orientation of microsomal vesicles. Studies at different temperatures were performed. At 30 degrees C membrane-associated particles are randomly distributed on membrane A-faces, while aggregations of particles are observed at 4 degrees C. (2) Aggregation is dependent on the cooling rates. It can be prevented by shock-freezing. (3) Particle aggregation is also prevented by cholesterol, added to the microsomes in equal molar ratio to the microsomal phospholid content. (4) These findings suggest that particle aggregation is caused by a partial freezing-out of phospholipid molecules during the phase transition from the liquid-crystalline to the gel state. (5) The results are discussed with respect to an observed increase in activation energy of microsomal drug monooxygenation at lower temperature.
Serum immunoglobulin M, G, and A concentration levels in Turner's syndrome compared with normal women and men.
Serum concentrations of immunoglobulin G (IgG), immunoglobulin M (IgM) and immunoglobulin A (IgA) were determined in 15 women with a lack of X chromsome material (Turner's syndrome), and compared with the immunoglobulin concentrations in normal men and women. Further, the investigation is supplemented by a comparison of normal women and the Turner group matched according to age. The serum concentrations of IgG and IgA in women with Turner's syndrome were very close to the concentration in serum from normal men, whereas the concentration of IgM was significantly lower. Compared to normal women the concentrations of IgG and IgM were significantly lower, and the concentration of IgA significantly higher in the Turner group. Whether these differences in serum immunoglobulins are determined by hormonal factors or under direct genetic control linked to the X chromosomes, is discussed.
[Turner's syndrome 4 variants].
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Ca2+-induced fusion of golgi-derived secretory vesicles isolated from rat liver.
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Twins in the sibships and parental sibships of women with Turner's syndrome.
The twin birth frequency in the sibships of 45 females with Turner's syndrome was 3.7% for the 21 females with 45,X and 5.7% for the 24 with other karyotypes. The 5.7% is significantly higher than the expected mean frequency of 1.4% in the Danish population from 1900 to 1974. The twin birth frequency in the sibships of the mothers of the 24 females with karyotypes other than 45 X was 4.7% which is also significantly higher than expected. The twin birth frequency in the sibships of the 21 mothers of 45,X females did not deviate significantly from the expected frequency, and nor did that of the father's sibships. It is concluded that these findings indicate that there might be an association between the increased risk of X chromosome aberration in the progeny due to mitotic non-disjunction, isochromosome or ring chromosome formation on one hand, and twin formation on the other hand. Such X chromosome aberration and twin formation might thus have some common aetiological factors, and some of the possibilities are discussed.
Intracellular membrane junctions during the exocytosis of insulin.
In the process of insulin release by exocytosis, a fusion between the membranes of secretory vesicles and the plasma membrane occurs which is followed by the rupture of these membranes and the formation of an exocytotic stoma. As revealed by freeze-fracturing, the membrane structure is altered in the region of membrane interaction. An accumulation of membrane-associated particles can be observed in membranes of secretory vesicles contacting the plasma membrane. At the exocytotic stoma the boundary between granule limiting membrane and plasma membrane is occasionally outlined by a ring-like aggregation of membrane-associated particles. The effects of hypertonic solutions on tissue structure indicate that the membrane junctions during exocytosis are permeable to ions and small molecules, forming a communication between the interior of the secretory vesicle and the extracellular space.
Unbalanced X-autosomal translocation with inactivation of the normal X chromosome.
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Chromosome studies in 30 children with Turner's syndrome.
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Chromosomal conditions in congenital heart disease.
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[Fixed saddles in connection with Scialom pin implants].
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[The Rorschach test used to investigate patients with anorexia nervosa].
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[Report on success with Superplants].
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[On the determination of the pathological disintegration of intelligence in the Hamburg Wechsler Intelligence Test for Adults by means of the disintegration quotient].
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Ductus arteriosus with pulmonary hypertension. Physical findings in 20 children under the age of 2 years.
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