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Biomedical subjects

W Hamann

Publications and source records attributed to W Hamann.

At least 37 records · Page 2Linked to original sources
PubMed1991

Cytotoxic and proliferative functions of T lymphocyte clones derived very shortly after allogeneic bone marrow transplantation.

In a search for mechanisms of potential graft-versus-leukaemia (GVL) activity after allogeneic bone marrow transplantation (BMT), peripheral lymphocytes from five patients (four chronic myeloid leukaemia, one acute lymphoblastic leukaemia) 24-39 days post-transplant were precultured with pretransplant host leukaemia cells and then cloned by limiting dilution with interleukin-2 (IL-2). Clones obtained were exclusively CD3+ CD56-, carried the alpha/beta form of the T cell receptor for antigen, and were mostly (88% of 138) CD4+. None of 143 clones, including CD8+ clones, convincingly lysed host pretransplant cells, although 35 (24.5%) manifested lytic potential in lectin-mediated cytotoxicity assays. Measuring the proliferative responses of 118 of these clones in the presence of exogenous IL-2 revealed that a small number of clones reacted more strongly to host leukaemia than to unrelated leukaemias or B lymphoblastoid cell lines. In the two cases tested, the donor's untransplanted lymphocytes cloned under the same conditions as post-transplant cells did not generate any clones reacting preferentially with host leukaemia cells. These results may suggest that some T cells appearing shortly after allogeneic BMT could potentially mediate anti-leukaemia activity not associated with cytolysis of target cells.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1990

Acute effects of neomycin on slowly adapting type I and type II cutaneous mechanoreceptors in the anaesthetized cat and rat.

1. Slowly adapting type I (SAI) and type II (SAII) mechanoreceptors in the skin were studied in anaesthetized cats and rats employing mechanical stimuli every 30 s. Individual stimuli rose within 200 ms to a plateau force which was kept constant through a feedback control unit for 2000 ms. 2. In cats, close arterial infusion of neomycin (2.5 mg/min) as sulphate was given through a side branch into the femoral blood stream for 5, 10 or 20 min at a rate of 0.025 ml/min. At other times saline was infused at the same rate. 3. After 20 min of neomycin infusion (total 50 mg) nervous discharge of cat SAI receptors was suppressed to about 30% of the control responses before neomycin infusion. Nervous responses were reduced more profoundly during the plateau phase of stimulation than during the dynamic phase. The interspike interval histogram was severely distorted. 4. In contrast, cat SAII receptors maintained about 70% of their control response after 20 min of neomycin infusion. The interspike interval histogram showed an orderly shift towards longer intervals maintaining its normal shape. 5. In rats, intradermal microinfusion of neomycin (30 micrograms/min) through a glass micropipette into the immediate vicinity of the receptor under investigation resulted in severe transient suppression of SAI receptor responses to about 10% of the control level. Receptor responses recovered almost completely about 1 h after the end of neomycin application. 6. It is concluded that the observed differences between the two types of slowly adapting mechanoreceptors are consistent with the hypothesis that the SAI receptor functions as a secondary sensory receptor, with a synaptic link between the Merkel cell and the primary afferent neurone.

Animals↗
PubMed1989

Interleukin 2-induced protein phosphorylation/dephosphorylation in human non-adherent peripheral blood mononuclear cells: initial phosphorylation of two 75-kDa proteins.

The kinetics of protein phosphorylation/dephosphorylation induced by IL-2 in cells of the non-adherent subpopulation of human peripheral blood mononuclear cells after pretreatment with and without phytohaemagglutinin (PHA) was analyzed by two-dimensional gel electrophoresis. In cells not pretreated with PHA, IL-2 induced the phosphorylation of two 75-kDa proteins with pI values 6.6 and 6.9, detectable 30 min after addition of IL-2, and the dephosphorylation of a 94-kDa (pI 4.0) protein, two 85-kDa (pI 5.2 and 5.4) proteins and a 65-kDa (pI 4.9) protein. The latter three phosphoproteins were found to be unlabelled after PHA pretreatment, but upon IL-2 stimulation the 94-kDa and the 85-kDa proteins became labelled simultaneously with two minor phosphoproteins of 68 kDa (pI 5.7) and 37 kDa (pI 4.8). Moreover, PHA pretreatment of cells induced a drastic phosphorylation of a 48-kDa (pI 6.5) and a 46-kDa (pI 6.7) protein, which were gradually dephosphorylated after IL-2 addition. Phosphorylation of the 75-kDa proteins could not be detected when the cells were pretreated with PHA prior to labelling. These results suggest that IL-2-induced phosphorylation of the 75-kDa proteins is one of the early events in IL-2 stimulation, an event already completed in PHA-pretreated cells since PHA is known to induce release of IL-2. Furthermore, the retarded appearance of the labelled 75-kDa proteins suggests an IL-2-induced de novo synthesis, possibly reflecting the expression of the 75-kDa alpha chain of the IL-2 receptor.

Antibodies, Monoclonal↗
PubMed1986

Reduced responsiveness of touch (SA I) receptors in the cat following close arterial infusion of neomycin.

Electrophysiological recordings were made from afferent nerve fibres supplying slowly adapting type I (SA I) cutaneous mechano-receptors in the cat during application of mechanical stimuli (20 mN constant force, 0.2 s rise time and 2 s plateau phase, every 30 s). Close arterial infusion of neomycin (2.5 mg/min for 5 min) strongly depressed the responsiveness of SA I receptors. A direct effect on the receptor is thought to be the mode of action.

Animals↗
PubMed1986

Embryological and diagnostic aspects of seminal vesicle cysts associated with upper urinary tract malformation.

Congenital seminal vesicle cysts represent a rare but illustrative type of embryological malformation. They often are combined with ipsilateral upper urinary tract abnormalities. In most of the cases described in the literature the diagnosis has been made with rather invasive procedures. On the basis of our experience with 3 cases we recommend pelvic ultrasonography as the initial study in patients in whom such a malformation is suspected. Although other radiological procedures may be required to confirm the diagnosis, this approach appears to be cost-effective and accurate in most instances. The treatment of such malformations should be restricted to symptomatic cases and usually consists of vesiculectomy with or without removal of the ipsilateral dysplastic or hypoplastic kidney.

Adult↗
PubMed1986

Mechanical properties of skin and responsiveness of slowly adapting type I mechanoreceptors in rats at different ages.

Slowly adapting type I (s.a. I) cutaneous mechanoreceptors were studied in young (3-4 months old) and adult (9-11 months old) rats. Trains of thirty repetitive mechanical stimuli with 0.1 s rise time, 1.9 s plateau phase, and 0.7 s interstimulus interval were applied. A feed-back mechanism maintained the force of stimulation at 20 mN during the plateau phases of stimuli and the contact force between stimuli at 0.5 mN. During the first few stimuli in a train residual indentation at contact force increased rapidly. Maximal indentation required to maintain the force of stimulation of 20 mN increased as well but to a smaller extent. Thus, the stroke amplitudes of individual stimuli decreased with increasing stimulus number. All displacement values in the group of adult rats were consistently reduced to 62 +/- 3% of the respective values in the group of young rats, indicating a linear decrease in skin compliance in the force range of 0.5-20 mN. Nervous responses to individual stimuli decreased from about 200 impulses for stimulus number 1 to about 60 impulses for stimulus number 30. Significant differences in the number of impulses between young and adult rats were observed from stimulus number 9 to number 16 only. It is concluded that the design of the s.a. I receptor allows maintained high tactile sensitivity in response to force-related stimuli irrespective of age-induced changes in mechanical properties of the skin and underlying tissues.

Action Potentials↗
PubMed1986

Responsiveness and ultrastructure of slowly adapting type I cutaneous mechanoreceptors in vitamin A deficient rats.

Single-unit recordings were made from afferent nerve fibres supplying slowly adapting type I (s.a. I) cutaneous mechanoreceptors in anaesthetized vitamin A deficient and control rats. Trains of thirty repetitive mechanical stimuli with 0.1 s rise time, 1.9 s plateau phase, and 0.7 s interstimulus interval were applied. A feed-back mechanism maintained the force of stimulation at 20 mN during the plateau phases and the contact force between stimuli at 0.5 mN. All displacement values in the group of vitamin A deficient rats were significantly larger than the corresponding control values. Residual indentations were increased by 70-100% while maximal indentations were only about 40% higher. These results indicate a non-linear increase in compliance of the skin and underlying tissues. S.a. I receptors were found to be significantly less responsive in vitamin A deficient animals. Mean numbers of impulses were about 25% lower in the vitamin A deficient group than in controls throughout the entire train of thirty stimuli. In vitamin A deficient rats, Merkel cells and adjoining nerve terminals showed signs of degeneration of a variety of cell organelles, particularly the mitochondria. Degenerative changes induced by vitamin A deficiency especially in the Merkel cells appeared to be a major cause of the reduction of responsiveness in s.a. I receptors.

Animals↗
PubMed1975

[Intraoperative rapid cytological assessment of mammary tumors (author's transl)].

A quick staining technique is reported which permits a full cytological statement on the seriousness of mammary tumors within 2 minutes intraoperatively. The accuracy of the method is comparable to that of histological examination. Between 1971 and 1974 a cytological rapid examination was carried out for the assessment of the seriousness of a total of 409 mammary tumors intraoperatively. 71 (equals 17.5 per cent) of the 409 tumors were carcinomas. In 70 of the carcinomas, the severity was confirmed histologically. The method can also be performed in small hospitals which have no pathology laboratory available.

Adenofibroma↗