Search PubMed⌕ Search

Biomedical subjects

S Mertens

Publications and source records attributed to S Mertens.

27 records · Page 2Linked to original sources
PubMed1990

Identification of the gamma 2-subunit protein in native GABAA receptors in brain.

GABAA receptors with functional benzodiazepine receptors have been reconstituted by coexpression of alpha-, beta- and gamma-subunit cDNAs. In brain, proteins of the alpha- and beta-subunits, but not the gamma 2-subunit have been identified. Using an antipeptide antiserum, we now demonstrate that the gamma 2-subunit is a protein of 43 kDa. It is present in at least 50% of GABAA receptors, as shown by immunoprecipitation.

Amino Acid Sequence↗
PubMed1990

Metabolism of exogenous substrates by coronary endothelial cells in culture.

The ability of coronary endothelial cells in 14 day confluent cultures to metabolize glucose, palmitate, lactate and various amino acids was investigated. Under aerobic conditions, 99% of glucose, (5 mM) was degraded to lactate and only 0.04% was oxidized in the Krebs cycle. One percent of the glucose catabolized was directed into the hexose monophosphate pathway, but this fraction could be increased by 81% by 0.4 mM methylene blue. Glucose oxidation in the Krebs cycle was increased at glucose concentrations lower than 1 mM, or by the uncoupler 2,4-dinitrophenol. Oxidation to CO2 of palmitate (300 microM), lactate (1 mM), and glutamine (0.5 mM) was diminished in the presence of glucose (5 mM) by 80, 66, and 48%, respectively. These results demonstrate that coronary endothelial cells utilize exogenous glucose, at physiological concentration, predominantly for glycolytic energy production. The metabolic pattern is characteristic of the Crabtree effect. In these cells, glucose not only effectively suppresses the oxidation of the substrates lactate and palmitate, i.e. of substrates preferred by the whole heart, but also of glutamine, which is a major oxidative substrate for coronary endothelial cells. Absolute rates of substrate catabolism are low as compared to those of the beating heart indicating a low energy demand of coronary endothelial cells.

Adenine Nucleotides↗
PubMed1990

Energetic response of coronary endothelial cells to hypoxia.

The response of endothelial energy metabolism to oxygen supply was studied in cultured coronary endothelial cells from the rat at defined PO2 levels between 0.1 and 100 Torr. In the presence of glucose (5 mM), endothelial respiration (4 nmol O2.min-1.mg protein-1) was independent of the exterior PO2 greater than 3 Torr; oxygen consumption was half maximal at 0.8 Torr. At 100 Torr, lactate production was 26 nmol.min-1.mg protein-1; the decrease of the PO2 to 0.1 Torr resulted in a 2.2-fold increase in lactate production. The contents of ATP, ADP, and AMP were 21, 4, and 2 nmol/mg protein, respectively; they remained constant for 2.5-h incubations at PO2 levels between 0.1 and 100 Torr. In the presence of palmitate (100 microM) plus glutamine (0.5 mM), oxygen consumption was 8 nmol.min-1.mg protein-1 at PO2 levels greater than 3 Torr, and the half-maximal rate was again observed at 0.8 Torr. Lactate production was negligible. At PO2 levels greater than 3 Torr, the cells remained well energized. Below 3 Torr, however, the adenine nucleotide contents rapidly declined. These results demonstrate that the oxygen demand of coronary endothelial cells is low compared with the beating myocardium. In the presence of glucose, aerobic glycolysis is pronounced and the Pasteur effect small. In severe hypoxia (PO2 less than 0.1 Torr) the energetic state remained stable. In the absence of glucose, the energetic state of coronary endothelial cells is sensitive to the exterior PO2 less than 3 Torr, declining concomitantly with the decrease in respiration.

Animals↗
PubMed1989

Resuscitation of hemorrhage with intraosseous infusion of hypertonic saline/dextran.

We resuscitated unanesthetized bled sheep (bled volume = 1.2-1.7 liters) with 200 ml of hypertonic saline/dextran 70 infused either through a peripheral vein (n = 6) or directly into the red marrow of the sternum (n = 6). Intraosseous infusion of the viscous 7.5% NaCl/6% dextran solution required 2-4 min. Plasma sodium was rapidly increased to the same level in both groups demonstrating equally rapid entry into the vascular space. Both regimens provide rapid and sustained normalization of arterial pressure and cardiac output. No significant differences between the two groups were apparent for any measured variable. Intraosseous infusion of hypertonic resuscitation fluids merits further research to evaluate the safety and efficacy for prehospital treatment of hypovolemia and trauma.

Animals↗
PubMed1988

Airway blood flow distribution and lung edema after histamine infusion in awake sheep.

The present study was designed to evaluate the distribution of bronchial blood flow to major airways and peripheral lung and to quantitate lung edema during a 2-h histamine infusion (2 micrograms.kg-1.min-1) in unanesthetized sheep. By the use of radioactive microspheres, the blood flow to trachea and to tracheal cartilage, smooth muscle, and mucosa/submucosa was determined along with measurements of blood flow to different sized airway segments and the systemic blood flow to lung parenchyma. Histamine greatly increased blood flow to medium-sized (5- to 10-mm-diam) central airways in which blood flow increased 5-10 times base line, whereas in small (1- to 5-mm-diam) central airways the increase was 10-15 times. Blood flow in tracheal mucosa/submucosa increased six times base line, but in tracheal smooth muscle the increase was only three times base line, and in cartilage it remained at base line. Most of the systemic blood flow to the lung perfuses less than 1-mm-diam peripheral airways, and these airways demonstrated less vasodilation during histamine infusion. Mean blood flow to whole-lung parenchyma (whole lung minus trachea) was only two times base line during histamine infusion. Water content of trachea and main stem bronchi was significantly increased after histamine. Histopathologic findings after histamine infusions included congestion and edema of airways with only minor effects noted in alveoli. We conclude that histamine is a potent and selective vasodilator of bronchial vessels and particularly affects blood flow to central airways and to airway mucosal/submucosa.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Impact of facial burns on the family.

At the University Burn Unit in Leuven (Belgium), we have been working for 4 years now with a multidisciplinary reintegration program. Our team consists of a plastic surgeon (head of the unit), a physical therapist, a social worker and a child psychiatrist. We set up family, context-oriented counselling for the families of seriously burned patients. In this paper, we would like to illustrate some aspects of the importance of facial scars in our society as well as the consequences of such scars for the families of patients. These are 2 essential aspects which have to be taken into account so that the counsellors and family do not reach a deadlock. We discuss how this therapy can be applied. Cooperation with the school is a keystone in the application of such therapy. The teacher is involved as a reflection of the feelings of the parents. Via this intermediary they learn how to cope with their feelings and to talk about them. The team has experienced this as an important step in the construction of family therapy.

Adult↗
PubMed1979

Neuropsychological study in treated thyroid dysgenesis.

Neuropsychological assessment was carried out in 57 patients aged 3.0 to 17.5 years (mean 8.5) with thyroid dysgenesis under adequate long-term therapy. Starting age of hypothyroidism as estimated by bone age at diagnosis was prenatal in 32 cases, close to birth in 13 cases and postnatal of 1-12 months in 12 cases. Hypothyroidism of prenatal onset results in severe neuropsychological disorders and mental retardation if not treated early. Only some signs of "minimal brain dysfunction" which compensate with advancing age and normal IQ are found in these children if therapy is started before one month of age. Hypothyroidism starting at birth does not result in mental retardation but neuropsychological disorders are found. They are more frequent if treatment is started after 6 months of age. Children who become hypothyroid between 1 and 12 months of age are usually not mentally retarded and show minor neuropsychological disorders.

Adolescent↗
PubMedDate not supplied

Fatty acids are not an important fuel for coronary microvascular endothelial cells.

The metabolism by coronary microvascular endothelial cells (CMEC) of the heart typical substrates palmitate and lactate was compared to that of glucose and glutamine. Confluent cultures of CMEC were used. Palmitate oxidation was saturable and independent of the exogenous albumin concentration. Palmitate, 300 microM, lactate, 1 mM, and glutamine, 0.5 mM, were oxidized to 35, 46, and 56 nmol CO2/h x mg protein. These oxidation rates were decreased by 80, 66, and 48% in presence of 5 mM glucose. The largest energy yield was obtained by glycolytic breakdown of glucose. Glucose, 5 mM, was degraded to lactate by 99%, and oxidized in the Krebs cycle by only 0.04%. 1% was catabolized via the hexose monophosphate pathway. The rate of glucose oxidation in the Krebs cycle could be 30-fold increased by the uncoupler 2,4-dinitrophenol, 30 microM. At concentrations lower than 1 mM the amount of glucose oxidized in the Krebs cycle also grew, indicating existence of the Crabtree effect. The energy demand of CMEC seems to be of the same order as that of the arrested heart.

Animals↗