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Biomedical subjects

M Michaelis

Publications and source records attributed to M Michaelis.

At least 73 records · Page 4Linked to original sources
PubMed1991

Rapid phasic baroreceptor inhibition of the activity in sympathetic preganglionic neurones does not change throughout the respiratory cycle.

We tested the hypothesis that the inhibitory influence of rapid phasic arterial baroreceptor stimulation on activity in sympathetic preganglionic neurones is weaker in inspiration than in expiration. Using neurophysiological techniques, 59 single preganglionic neurones with typical reflex pattern of muscle vasoconstrictor neurones that projected in the cervical sympathetic trunk were analysed. The inhibitory modulation of the ongoing activity in these neurones by the pulsatile activation of the arterial baroreceptors was determined by constructing post-R-wave histograms separately for both respiratory phases (as indicated by the discharge in the phrenic nerve). Quantitative measurements showed that the inhibition of the activity in the preganglionic neurones following phasic stimulation of arterial baroreceptors by the pulse pressure wave was not statistically different in both respiratory phases, even with increased respiratory drive.

Animals↗
PubMed1990

Changes of activity in lumbar preganglionic neurones during slow urinary bladder filling in the cat.

The hypothesis was tested that sympathetic neurones projecting to the pelvic organs are excited during the collecting phase of the urinary bladder and inhibited when the intravesical pressure is beyond micturition threshold. Activity in single lumbar sympathetic preganglionic neurones projecting in the lumbar splanchnic nerves was measured when intravesical pressure was increased by slow filling at 2 ml/min in anaesthetized cats. Nine of 10 neurones tested were excited in a graded manner up to an intravesical pressure of 50 mmHg and during isovolumetric bladder contractions. On the basis of these quantitative results the hypothesis was refuted. The functional implications are discussed.

Action Potentials↗
PubMed1989

Identical forms of the CD2 antigen expressed by mouse T and B lymphocytes.

A monoclonal antibody (12-15) reactive with the mouse CD2 was used to study the expression of the antigen in different lymphoid cell subsets. By two-color immunofluorescence using B or T cell-specific reagents and cell sorting in combination with biochemical analysis we provide evidence that the CD2 antigen is present on mouse B and T cells. The antigen is expressed by both subsets at similar density and appears to be biochemically indistinguishable.

Animals↗
PubMed1977

Malakoplakia of the colon and rectum: report of a case and review of the literature.

A case of malakoplakia with primary involvement of the sigmoid colon and rectum in a 19-year-old man who died by extension of the disease to the bladder, right ureter, and retroperitoneum 4 years after the diagnosis was established is presented. A review of the 20 previously reported cases of malakoplakia of the colon is included also.

Adolescent↗
PubMedDate not supplied

Cytotoxicity of L-cycloserine against human neuroblastoma and medulloblastoma cells is associated with the suppression of ganglioside expression.

BACKGROUND: Human neuroblastoma and medulloblastoma express abnormal ganglioside patterns especially GD2 and GM2 which are important for tumour growth. We tested the effects of L-cycloserine (L-CS), a potent inhibitor of synthesis of glycosphingolipids, on the growth, viability and expression of GD2 and GM2 in neuroblastoma and medulloblastoma cells. MATERIALS AND METHODS: The cytotoxic effects of L-CS were tested using the MTT dye reduction assay on four neuroblastoma (IMR-32, SK-N-SH, UKF-NB-2 and UKF-NB-3), two medulloblastoma (D283 and D341) and normal human fibroblasts and epithelial cell lines. In some experiments cytotoxicity of L-CS was tested in the presence of exogenous GD2 and GM2. The expression of GD2 and GM2 was analysed by flow cytometry. The antitumoral effects of L-CS in vivo were assessed on established xenografts of UKF-NB-3 or D283 cells in athymic (nude) mice using systemic administration of the drug (150 mg/kg intraperitoneally, once per day on 20 consecutive days). RESULTS: In vitro experiments revealed that L-CS was toxic for tumour cells at concentrations ranging from 0.5 to 20 micrograms/ml without any significant effects on normal fibroblasts and epithelial cells. L-CS treatment of UKF-NB-3 and D283 cells significantly inhibited expression of GD2 and GM2. The addition of exogenous GD2 and GM2 to culture medium partially prevented cytotoxic effects of L-CS on tumour cells. In vivo treatment resulted in complete tumour regression of UKF-NB-3 xenografts whereas growth of D283 xenografts was reduced by 60%. CONCLUSIONS: L-CS is a selective antitumoral agent for neuroblastoma and medulloblastoma cells with the ability to reduce expression of tumour associated gangliosides. In vivo experiments suggest that L-CS may be effective drug for treatment of neuroblastoma and medulloblastoma.

Animals↗