Interaction between anandamide and sphingosine-1-phosphate in mediating vasorelaxation in rat coronary artery

Background and purpose:

This study establishes a pharmacokinetic/pharmacodynamic (PK/PD) model to describe the time course and in vivo mechanisms of action of the antinociceptive effects of lumiracoxib, evaluated by the thermal hyperalgesia test in rats.

Experimental approach:

Female Wistar fasted rats were injected s.c. with saline or carrageenan in the right hind paw, followed by either 0, 1, 3, 10 or 30 mg·kg⁻¹ of oral lumiracoxib at the time of carrageenan injection (experiment I), or 0, 10 or 30 mg·kg⁻¹ oral lumiracoxib at 4 h after carrageenan injection (experiment II). Antihyperalgesic responses were measured as latency time (LT) to a thermal stimulus. PK/PD modelling of the antinociceptive response was performed using the population approach with NONMEM VI.

Results:

A two-compartment model described the plasma disposition. A first-order model, including lag time and decreased relative bioavailability as a function of the dose, described the absorption process. The response model was: LT=LT₀/(1 +MED). LT₀ is the baseline response, and MED represents the level of inflammatory mediators. The time course of MED was assumed to be equivalent to the predicted profile of COX-2 activity and was modelled according to an indirect response model with a time variant synthesis rate. Drug effects were described as a reversible inhibition of the COX-2 activity. The in vivo estimate of the dissociation equilibrium constant of the COX-2-lumiracoxib complex was 0.24 µg·mL⁻¹.

Conclusions:

The model developed appropriately described the time course of pharmacological responses to lumiracoxib, in terms of its mechanism of action and pharmacokinetics.     

Parental α 1-antitrypsin (PI) types and meiotic nondisjunction in the aetiology of Down syndrome

In 100 children with Down syndrome (DS), the parental origin of the supernumery chromosome 21 was investigated. In 76 out of the 100 cases the polymorphic regions were informative, i.e. the nondisjunction could be traced. Assessment of the alpha 1-antitrypsin/alpha 1-protease inhibitor (PI) types in these DS children revealed a significantly higher value of non-M PI variants (P less than 0.05). In their fathers the non-M PI variants were not increased, not even in those in whom nondisjunction had taken place. A clearly significantly higher value (P less than 0.001) of non-M PI variants was found in their mothers, particularly when only the MS and MZ types which are recognised as deficiency variants were considered. Most striking, however, is the almost 5-fold increased frequency of MS and MZ types found in mothers where the nondisjunction had occurred during the first meiotic division. This would suggest that PI deficiency interferes with some process leading to non-disjunction. If these findings are confirmed, application of Bayes' theorem enables us to estimate the risk for MZ and MS heterozygous women to have a DS child: this would be 3- to 4- fold higher than for MM homozygous women. This would be of interest for genetic counselling and enhance the benefits of prenatal diagnosis programmes.     

Genetic study of Tunisian Berbers. II. Alpha 1-antitrypsin (Pi) polymorphism: report of a new allele (Pi S Berber)

The alpha 1-antitrypsin (alpha 1-AT) (Pi) polymorphism has been studied in three Berber groups of Tunisia by high-resolution isoelectric focusing. The results showed that actual Tunisian Berbers are mainly Caucasoid. A new variant of alpha 1-AT, tentatively called Pi S Berber, was found in the three Berber groups. On isoelectric focusing this variant was slightly more cathodal than the product of the usual Pi S allele. Family studies showed that the Gm-Pi linkage is probably close when the Pi locus supports the Pi P allele which is responsible for moderate (30%) serum alpha 1-AT deficiency.     

Relations between serum pepsinogen levels, pepsinogen phenotypes, ABO blood groups, age and sex in blood donors

Serum pepsinogen A (pepsinogen I) levels and urinary pepsinogen A phenotypes were studied in relation to ABO blood group, age and sex in 700 healthy blood donors. There was no relation between urinary pepsinogen A phenotypes and serum pepsinogen A levels. It is concluded that serum PGA levels and PGA phenotypes are independent factors in predisposition to gastroduodenal disorders. Serum pepsinogen A levels were higher in males than in females and rose with increasing age. The ABO blood groups were not related to pepsinogen A phenotypes. Blood group O individuals showed higher serum pepsinogen A levels compared with blood group A. Pepsinogen A phenotypes with intensity of fraction 5 were more frequent in males compared with females.     

Alpha-1 antitrypsin Null mutations and severity of emphysema

BACKGROUND: Alpha-1 antitrypsin (AAT) deficiency is an autosomal-codominant disorder, caused by mutations in the SERPINA1 gene on chromosome 14. Individuals affected by the most common mutations, SZ and ZZ, have serum AAT concentrations of 25% and 15% of normal levels, and present a higher risk of emphysema. Mutations causing total absence of serum AAT (Null mutations) were suggested to be associated with very early onset emphysema but their clinical phenotype is poorly known. HYPOTHESIS: Absence of AAT in Null mutations results in more severe emphysema as compared to ZZ and SZ. METHODS: We genotyped all known Dutch subjects (n=12) with absent serum AAT, and compared their lung function values (FEV1 and KCO) with those of individuals with ZZ and SZ genotype, matched for age and smoking history. RESULTS: All subjects with absent serum AAT presented homozygous Null mutations. In three subjects, a new mutation in exon 2 of the SERPINA1 gene was found. Subjects with Null mutations showed significantly lower lung function values than SZ and ZZ individuals (p=0.000 and 0.001 for FEV1 and KCO, respectively). In all groups, there was a positive correlation between serum AAT and lung function values (p=0.025 and 0.014 for FEV1 and KCO, respectively). CONCLUSIONS: Serum levels of AAT are correlated with the severity of pulmonary phenotype. Subjects with Null mutations should be considered a subgroup at particularly high risk of emphysema within AAT deficiency (AATD). Early detection of carriers of this genotype would be important for preventive and therapeutic interventions.     

Hypersensitivity pneumonitis: evaluation with CT

Thirteen chest radiographs and computed tomographic (CT) scans obtained from 11 patients with hypersensitivity pneumonitis were reviewed. The CT findings were correlated with open lung biopsy findings in seven patients. The two patients with acute hypersensitivity pneumonitis showed air-space opacification on CT scans. An open lung biopsy, done in one of these patients, demonstrated noncaseating granulomas and filling of the air spaces with macrophages. The nine patients with subacute hypersensitivity pneumonitis showed small, rounded opacities and patchy air-space opacification on CT scans. These findings reflected the histologic findings, which consisted of interstitial pneumonitis, cellular bronchiolitis, and small, noncaseating granulomas. The six patients with symptoms for 12 months or longer also showed irregular linear opacities on CT scans, corresponding to areas of fibrosis. CT scans were superior to radiographs in helping to assess the type and extent of abnormalities, and high-resolution CT scans were superior to conventional CT scans.     

A Locus Linked to p16 Modifies Melanoma Risk in Dutch Familial Atypical Multiple Mole Melanoma (FAMMM) Syndrome Families

The CDKN2A gene that encodes the cell cycle inhibitor p16 shows mutations in many but not all 9p21-linked melanoma families. Most Dutch melanoma families segregate for a unique founder mutation (p16-Leiden), encoding a truncated nonfunctional p16 protein. The highly variable risk for p16-Leiden carriers to develop melanoma suggests a role for other genetic and/or environmental factors. We hypothesized that a 9p21 gene other than CDKN2A may be relevant in the remaining 9p21-linked melanoma families without p16 mutations but may also act as a risk modifier in p16-Leiden carriers. Haplotype analysis for 9p21 was performed using microsatellite markers in six p16-Leiden families originating from a founder population. p16-Leiden carriers in two families shared an unexpectedly large founder haplotype ( approximately 20-cM) around CDKN2A, mostly in proximal direction. Melanoma-positive p16-Leiden carriers from these families showed this extensive proximal haplotype compared with melanoma-negative p16-Leiden carriers from the same families. Additional p16-Leiden families less heavily affected with melanoma showed shorter haplotypes sharing, excluding the region proximally of CDKN2A. The presence of a gene involved in melanoma susceptibility proximal of CDKN2A is corroborated by somatic deletions of 9p in tumors, which frequently do not include CDKN2A but a more proximal chromosomal area instead. Our results provide a candidate region for further gene mapping in p16-negative 9p21-linked melanoma families and guide the search for risk modifiers in melanoma development.