Biomedical subjects

M Looman

Publications and source records attributed to M Looman.

4 recordsLinked to original sources

PubMed2004

Increased expression of CCL18, CCL19, and CCL17 by dendritic cells from patients with rheumatoid arthritis, and regulation by Fc gamma receptors.

BACKGROUND: Dendritic cells (DC) have a role in the regulation of immunity and tolerance, attracting inflammatory cells by the production of various chemokines (CK). Fc gamma receptors (Fc gamma R) may be involved in regulation of the DC function. OBJECTIVE: To assess the expression of CK by immature (iDC) and mature DC (mDC) and its regulation by Fc gamma R in patients with RA and healthy donors (HC). METHODS: Expression of CK by DC from patients with RA and from HC was determined by real time quantitative PCR and ELISA. DC were derived from monocytes following standardised protocols. To study the potential regulation by Fc gamma R, iDC were stimulated with immune complexes (IC) during lipopolysaccharide (LPS) induced maturation. The presence of CK was studied in synovial tissue from patients with RA, osteoarthritis, and healthy subjects by RT-PCR and immunohistochemistry. RESULTS: iDC from patients with RA had markedly increased mRNA levels of the CK CCL18 and CXCL8. Upon maturation with LPS, expression of CCL18, CCL19, CXCL8, CCL3, and CCL17 increased dramatically, reaching significantly higher levels in patients with RA. Monocytes failed to express these CK, except for CXCL8 and CCL3. IC-mediated triggering of the Fc gamma R on DC from patients with highly active RA down regulated all CK, whereas the reverse was seen when DC from patients with low disease activity and healthy donors were stimulated. CCL18 was significantly increased in RA synovial tissue. CONCLUSION: Increased CK expression by DC was found in patients with RA. This expression is partly regulated by Fc gamma R triggering and results in an inhibitory DC subtype in RA upon Fc gamma R-mediated triggering.

Arthritis, Rheumatoid↗

PubMed2001

Point mutation in the stalk of angiotensin-converting enzyme causes a dramatic increase in serum angiotensin-converting enzyme but no cardiovascular disease.

BACKGROUND: Angiotensin-converting enzyme (ACE) metabolizes many small peptides and plays a key role in blood pressure regulation. Elevated serum ACE is claimed to be associated with an increased risk for cardiovascular disease. Previously, two families with dramatically increased serum ACE were described, but no systematic survey of affected individuals was performed, and the molecular background of this trait is unknown. METHODS AND RESULTS: Eight families were identified with autosomal dominant inheritance of a dramatic (5-fold) increase of serum ACE activity. Strikingly, no clinical abnormalities were apparent in the affected subjects. Isolated blood cells were used for genetic and biochemical analysis. The level of ACE expression on the blood leukocytes and dendritic cells and total cell-associated ACE of the affected individuals was similar to that in nonaffected relatives; however membrane-bound mutant ACE was much more efficiently clipped from the cell surface compared with its wild-type counterpart. A point mutation causing Pro1199Leu in the stalk region of the ACE molecule cosegregates with the increase in serum ACE (LOD score, 6.63). CONCLUSIONS: A point mutation in the stalk region of the ACE protein causes increased shedding, leading to increased serum ACE, whereas cell-bound ACE is unaltered, and affected individuals exhibit no clinical abnormalities. These findings qualify the importance of serum ACE and establish a new determinant of ACE solubilization.

Adult↗

PubMed1998

Mutation frequency of cystic fibrosis transmembrane regulator is not increased in oligozoospermic male candidates for intracytoplasmic sperm injection.

OBJECTIVE: To examine the frequency of anomalies of the vas deferens and the frequency of mutations of the cystic fibrosis transmembrane regulator (CFTR) gene in male candidates for intracytoplasmic sperm injection (ICSI) who had severe oligoasthenoteratozoospermia. DESIGN: The clinical data for male candidates for ICSI were studied. The three most frequent cystic fibrosis (CF)-causing CFTR mutations in the Dutch population (deltaF508, A455E, and G542X) and the three most frequent CFTR mutations potentially causing congenital bilateral absence of the vas deferens (CBAVD) in the Dutch population (deltaF508, R117H, and IVS8-5T) were analyzed. Delta I507 is also detected by the deltaF508 test. Samples of DNA from patients identified as CFTR mutation carriers were subjected to denaturing gradient gel electrophoresis analysis with use of a two-dimensional electrophoretic technique. SETTING: University-based center for reproductive medicine and clinical genetics. PATIENT(S): Male candidates for ICSI who had oligoasthenoteratozoospermia and no history of operative sterilization and refertilization. Males with a chromosomal aberration or a Y-chromosome microdeletion were excluded. INTERVENTION(S): Semen and blood samples were collected from the patients at their first visit to the clinic. MAIN OUTCOME MEASURE(S): Frequency of anomalies of the vas deferens and frequency of mutations of the CFTR gene in male candidates for ICSI who had oligoasthenoteratozoospermia. RESULT(S): None of the patients had abnormalities of the vas deferens at physical examination. In 4 of the 150 chromosomes (75 patients), a CFTR mutation was found, yielding a CFTR mutation frequency of 2.7% (95% confidence interval, 1.0-6.7%). None of the patients had two CFTR mutations. CONCLUSION(S): The frequency of congenital abnormalities of the vas deferens in patients with oligoasthenoteratozoospermia is low. The frequencies of the CFTR mutations identified in this cohort did not differ significantly from the frequencies found in the normal Dutch population.

Cystic Fibrosis Transmembrane Conductance Regulato↗

PubMed1985

Renal response to converting enzyme blockade.

To investigate the renal actions of the converting enzyme inhibitor enalaprilic acid, incremental doses of this drug were infused into the renal artery of hypertensive patients just before renal angiography. One group (n = 6) received doses of 0.1, 0.3 and 1 microgram/kg per min, while in another group (n = 7) doses of 1, 3 and 10 micrograms/kg per min were given. Each dose was infused for 10 min, at the end of which renal blood flow was assessed by means of xenon-washout. At the same time, blood was sampled from the renal artery and vein for determination of converting enzyme, renin and angiotensin II. Enalaprilic acid caused a dose-related suppression of converting enzyme activity, which was maximal at a dose of 1 microgram/kg per min; arterial levels fell more steeply than venous ones. Angiotensin II disappeared in parallel with the drop in converting enzyme. Renal blood flow, on the other hand, began to increase only when 3 micrograms/kg per min was given, and no further changes occurred with the highest dose. Intra-arterial blood pressure fell only when the highest dose was given. Renin secretion tended to increase, but changes were not statistically significant. It is concluded that systemic suppression of converting enzyme is needed for renal vasodilatation to occur. However, the renal vascular response comes well before blood pressure falls.

Angiotensin-Converting Enzyme Inhibitors↗