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Biomedical subjects

R Landmann

Publications and source records attributed to R Landmann.

44 records · Page 3Linked to original sources
PubMed1982

Elevated adrenaline and increased alpha-adrenoceptor-mediated vasoconstriction in essential hypertension.

In patients with essential hypertension, plasma adrenaline, regardless of age, was consistently higher than in normotensive controls; adrenaline correlated with heart rate and the vasodilator response in the forearm circulation produced by postjunctional alpha 1-adrenoceptor blockade with prazosin. This dilator response to prazosin was greater in hypertensive patients. Together, this suggests elevated sympathetic activity and enforced vasoconstriction via postjunctional alpha 1-adrenoceptors in essential hypertension. beta-Adrenoceptor-mediated cardiovascular responses decrease with age and even more with high blood pressure, which contributes to unopposed alpha-adrenoceptor-mediated vasoconstriction. This could explain the transition from an early high cardiac output into a later high peripheral resistance form of hypertension.

Adaptation, Physiological↗
PubMed1982

High-affinity binding sites for [3H] verapamil in cardiac membranes.

The calcium channel blocker [3H]verapamil showed specific binding of high affinity (equilibrium dissociation constant, KD, of 4.25 nM) and low density (maximal number of binding sites, Bmax, 50 fmol/mg protein) in frog heart membranes. Nitrendipine, a new calcium channel blocker, had a potency comparable to verapamil in the inhibition of [3H]verapamil binding. Concentrations of Ca2+ in the medium exceeding 3 mM decreased [3H]verapamil binding. These findings are consistent with the concept that high-affinity binding sites for calcium channel blockers are associated with sarcolemmal calcium channels.

Animals↗
PubMed1980

Plasma catecholamines and cardiac, renal and peripheral vascular adrenoceptor-mediated responses in different age groups of normal and hypertensive subjects.

The role of the sympathetic nervous system in cardiac, renal and peripheral vascular adrenoceptor-mediated responses was investigated in patients with essential hypertension and age-matched normotensive subjects. Regardless of age plasma adrenaline was significantly higher in hypertensive when compared with normotensive subjects. This suggests a sympatho-adrenal factor in essential hypertension. Plasma noradrenaline tended to increase with age but its similarity between normotensive and hypertensive subjects points to similar postganglionic neural activity and/or similar overflow of noradrenaline into the circulation. On the other hand, beta-adrenoceptor-mediated tachycardia in response to exercise and intravenous isoproterenol as well as the forearm vasodilator response to intraarterial isoproterenol decreased in normal subjects with older age. In hypertensives this age-dependent beta-receptor-related effect tends to be enhanced as judged from the greater reduction of cardiac isoproterenol sensitivity and the blunted renin response to exercise stimulation. The dilator response to alpha-adrenoceptor blockade with phentolamine was not different in both groups. Therefore a qualitative rather than quantitative derangement of sympathetic control of vascular resistance - in which beta-dilator effects are reduced and alpha-constrictor mechanisms prevail - may contribute to the maintenance of established hypertension.

Adult↗
PubMedDate not supplied

Human B cells express membrane-bound and soluble forms of the CD14 myeloid antigen.

The expression of the myeloid differentiation antigen CD14 on the B lineage was analyzed. A CD14-specific monoclonal antibody was used to isolate the antigen from normal B, B-type chronic lymphocytic leukemia cells, and a representative Epstein-Barr virus-transformed B lymphoblastoid cell line (EBVLCL). A soluble form of this protein was detected in the culture supernatant of all the B cell types tested. The molecule expressed in the normal B and B-type chronic lymphocytic leukemia cells was identical in size to the 52,000 mol. wt monocyte-isolated CD14 glycoprotein. A 64,000 mol. wt antigen was isolated from the lymphoblastoid cell line. Similar 2-D gel electrophoretic patterns to that of the monocyte-derived CD14 were obtained from the normal B and B-type chronic lymphocytic leukemia cell-isolated molecules. These similarities were reflected in minor isoelectric point (pI) differences between the polypeptide spots (pI 4.8), in the first dimension, and identical molecular weight (52,000) in the second dimension. The EBVLCL-isolated polypeptide, when analyzed by 2-D gel electrophoresis, showed a pI identical to that of the myeloid antigen (pI 4.6). The isolated soluble form was of smaller (47,000 mol. wt, normal B and B-type chronic lymphocytic leukemia cells) or similar size (64,000 mol. wt, lymphoblastoid cell line) compared with their corresponding membrane-bound forms. Interestingly, two-colour immunofluorescence analysis showed that only two out of four CD14-specific mAb tested bound to the B cells. We conclude that the CD14 antigen is, in fact, expressed in the B lineage. Its cell surface expression and serum level in the prognosis of B-type chronic lymphocytic leukemia patients needs to be evaluated.

Antigens, CD↗
PubMedDate not supplied

Role of lipopolysaccharide susceptibility in the innate immune response to Salmonella typhimurium infection: LPS, a primary target for recognition of Gram-negative bacteria.

Lipopolysaccharide is an important recognition marker by virtue of which the innate immune system senses and reacts against Gram-negative bacteria invading the LPS susceptible host. This review deals with the factors affecting LPS susceptibility and with the role of the latter in the course and outcome of Salmonella typhimurium infection.

Animals↗