A susceptibility gene for psoriatic arthritis maps to chromosome 16q: evidence for imprinting

Several genetic loci have been reported for psoriasis, but none has been specifically linked to psoriatic arthritis (PsA), a condition that affects >10% of patients with psoriasis. A genetic component for PsA is suggested by segregation within families and high concordance among identical twins. We performed a linkage scan to map genes contributing to PsA. We identified 178 patients with PsA out of 906 patients who were included in our genetic study of psoriasis. Using a comprehensive genealogy database, we were able to connect 100 of these into 39 families. We genotyped the patients using a framework marker set of 1,000 microsatellite markers, with an average density of 3 cM, and performed multipoint, affected-only, allele-sharing linkage analysis using the Allegro program. On the basis of the initial results, we genotyped more markers for the most prominent loci. A linkage with a LOD score of 2.17 was observed on chromosome 16q. The linkage analysis, conditioned on paternal transmission to affected individuals, gave a LOD score of 4.19, whereas a LOD score of only 1.03 was observed when conditioned for maternal transmission. A suggestive locus on chromosome 16q has previously been implicated in psoriasis. Our data indicate that a gene at this locus may be involved in paternal transmission of PsA.     

Growth and reproduction in the Icelandic common seal (Phoca vitulina L., 1758)

Length, weight and maturity were studied in relation to age in the common seal (Phoca vitulina vitulina L., 1758), collected during the periods 1979-1983 and 1990-2000 in Icelandic waters. The maximum age of common seal observed was 36 years for females and 30 years for males. For common seal females and males, asymptotic length and weight were 161 cm and 93 kg and 174 cm and 97 kg, respectively, showing slight sexual dimorphism in size. The condition of adult females, measured as fat thickness at the lower end of the sternum, was lower in the period 1979-1983 than in 1990-2000 during June-September, the breeding and mating time of the Icelandic common seal. Males reached sexual maturity between 5 and 7 years, whereas 50% of females did so at age 4 years. Including the length and age interaction term in the logistic regression model for the maturity of females significantly improved it. Thus, body size matters in the onset of maturity. The mean birthing date for the Icelandic common seal was found to be in early June. A comparison of animals collected in the two periods 1979-1983 and 1990-2000 did not show significant differences in growth and the average age of sexual maturity for either males or females. The observed decline of the Icelandic common seal population is most probably caused by increased mortality, due to exploitation and accidental by-catch in gill-nets, rather than a decrease in fecundity.     

Seasonal,meteorological, tidal and diurnal effects on haul-out patterns of harbour seals (Phoca vitulina) in Iceland

Polar Biology - It is of critical importance to identify factors that affect harbour seal haul-out patterns to improve the accuracy of harbour seal censuses. In this study, haul-out patterns of...     

Effect of head-group structure and counterion condensation on phase equilibria in anionic phospholipid-water systems studied by 2H, 23Na, and 31P NMR and X-ray diffraction

The phase equilibria, hydration, and sodium counterion association for the systems DOPA-2H2O, DOPS-2H2O, DOPG-2H2O, and DPG-2H2O were investigated with 2H, 23Na, and 31P NMR and X-ray diffraction. The following one-phase regions were found in the DOPA-water system: a reversed hexagonal liquid-crystalline (HII) phase up to about 35 wt % water and a lamellar liquid-crystalline (L alpha) phase between about 55 and 98 wt % water. The area per DOPA molecule was 36-65 A2 in the HII phase (10-40 wt % water) and 69 A2 in the L alpha phase (60 wt % water). DOPS and DOPG with 10-98 wt % water, and DPG with 20-95 wt % water formed an L alpha phase at temperatures between 25 and 55 degrees C. At temperatures above 55 degrees C, DPG with 20 and 30 wt % water formed a mixture of L alpha, HII, and cubic liquid-crystalline phases, the mole percent of lipid forming nonlamellar phases being smaller at 30 wt % water than at 20 wt % water. DPG with 10 wt % water probably formed a mixture of an L alpha phase and at least one nonlamellar liquid-crystalline phase at 25 and 35 degrees C, and a pure HII phase at 45 degrees C and higher temperatures. At water concentrations above about 50 wt % the 23Na quadrupole splitting was constant for all four lipid-water systems studied, implying that the counterion association to the charged lipid aggregates did not change upon dilution. These experimental observations can be described with an ion condensation model but not with a simple equilibrium model. The fraction of counterions located close to the lipid-water interface was calculated to be greater than 95%. The 2H and 23Na NMR quadrupole splittings of 2H2O and sodium counterions, respectively, indicate that the molecular order in the polar head-group region decreases for the L alpha phase in the order DOPA approximately DPG greater than DOPS greater than DOPG.     

Dissociation and unfolding of cold-active alkaline phosphatase from atlantic cod in the presence of guanidinium chloride.

Cold-adaptation of enzymes involves improvements in catalytic efficiency. This paper describes studies on the conformational stability of a cold-active alkaline phosphatase (AP) from Atlantic cod, with the aim of understanding more clearly its structural stability in terms of subunit dissociation and unfolding of monomers. AP is a homodimeric enzyme that is only active in the dimeric state. Tryptophan fluorescence, size-exclusion chromatography and enzyme activity were used to monitor alterations in conformational state induced by guanidinium chloride or urea. In cod AP, a clear distinction could be made between dissociation of dimers into monomers and subsequent unfolding of monomers (fits a three-state model). In contrast, dimer dissociation of calf AP coincided with the monophasic unfolding curve observed by tryptophan fluorescence (fits a two-state model). The DeltaG for dimer dissociation of cod AP was 8.3 kcal.mol-1, and the monomer stabilization free energy was 2.2 kcal.mol-1, giving a total of 12.7 kcal.mol-1, whereas the total free energy of calf intestinal AP was 17.3 kcal.mol-1. Thus, dimer formation provided a major contribution to the overall stability of the cod enzyme. Phosphate, the reaction product, had the effect of promoting dimer dissociation and stabilizing the monomers. Cod AP has reduced affinity for inorganic phosphate, the release of which is the rate-limiting step of the reaction mechanism. More flexible links at the interface between the dimer subunits may ease structural rearrangements that facilitate more rapid release of phosphate, and thus catalytic turnover.     

Heat-labile bacterial alkaline phosphatase from a marine Vibrio sp

Psychrophilic organisms have successfully adapted to various low-temperature environments such as cold ocean waters. Catalysts with increased catalytic efficiencies are produced, generally at the expense of thermal stability due to fewer non-covalent stabilizing interactions. A marine bacterial strain producing a particularly heat-labile alkaline phosphatase was selected from a total of 232 strains isolated from North-Atlantic coastal waters. From partial 16S rRNA sequences the strain was characterized as a Vibrio sp. An alkaline phosphatase was purified 151-fold with 54% yield from the culture medium using a single step affinity chromatography procedure on agarose-linked L-histidyldiazobenzylphosphonic acid. The active enzyme was a 55 +/- 6 kDa monomer. The enzyme had optimal activity at pH 10 and was strikingly heat-labile with a half-life of 6 min at 40 degrees C and 30 min at 32 degrees C. This enzyme from Vibrio sp. had a higher turnover number (k(cat)) and higher apparent Michaelis-Menten factor (K(m)) than the enzyme from Escherichia coli, a clear-indication of cold-adaptation. Inorganic phosphate was a competitive inhibitor with a relatively high K(i) value of 1.7 mM. Low affinity for phosphate may contribute to higher turnover rates due to more facile release of product.     

Increase in matrix metalloproteinases from endothelial cells exposed to umbilical cord plasma from high birth weight newborns

Large for gestational age infants have increased risk of developing the metabolic syndrome and cardiovascular disease in child- and adulthood. The vascular endothelium is a target site in the pathogenesis of many cardiovascular disorders. The matrix metalloproteinases (MMP) are important modulators of the extracellular matrix and serve as markers of these disorders. Here, we asked whether umbilical cord plasma of high birth weight (HBW; >4 kg) infants could modulate functional properties of human umbilical vein endothelial cells (HUVEC) compared with plasma from normal birth weight (NBW; 3.1-3.6 kg) infants. To test this, HUVECs were exposed for 48 h to 20% venous cord plasma from HBW or NBW infants. The MMP activity in supernatants of HUVECs exposed to HBW plasma was nearly three times higher (P < 0.05) than that obtained with NBW plasma. MMP-9, but not MMP-2, protein concentration and mRNA expression were enhanced in HBW (P < 0.05). With specific blockers, MMP activity and mRNA-MMP-9 were inhibited by approximately 60-70%. Cord lipid and insulin concentrations were similar (P > 0.05) among the two groups. We could not detect any significant differences between the two groups in the concentrations of proinflammatory cytokines or specific tissue inhibitors of MMP in plasma or HUVEC supernatants. In conclusion, cord plasma from HBW infants induced more MMP-9 in HUVECs compared with cord plasma from NBW infants. Although not identified, cord plasma of HBW infants may contain factors that increase endothelial cell MMP. These findings may indicate an association between fetal nutritional conditions and endothelial cell functions.     

Decreases in sealworm (Pseudoterranova sp. (p)) abundance in short-spined sea scorpion (Myoxocephalus scorpius scorpius) following declines in numbers of seals at Hvalseyjar, western Iceland

. Larval sealworm [Pseudoterranova sp. (p)] infections were surveyed in the short-spined sea scorpion (Myoxocephalus scorpius scorpius) in the shallow waters of the Hvalseyjar archipelago, western Iceland, in the summers of 1992, 1996 and 1999. Significant decreases in sealworm abundance in 1996 and 1999 were attributed to declines in local populations of grey (Halichoerus grypus) and common (Phoca vitulina) seals, final hosts for sealworm, between 1992 and 1998. The declines of the local seal populations were caused by over-exploitation, disturbances following hunting operation and accidental catch in fishing gear.     

Modification of pulse sequences reduces occupational exposure from MRI switched gradient fields: Preliminary results

The gradient fields in magnetic resonance imaging (MRI) will in some circumstances exceed the ICNIRP guidelines of occupational electromagnetic field exposure when personnel are near the scanner during MRI scanning. In this work we have shown that using commercially available modified sequences for noise reduction purposes, exposure will decrease by a factor of 1.5 with preserved image quality. This is a first step toward optimizing occupational exposure within the scanner room without affecting image quality. Bioelectromagnetics 31:85–87, 2010. © 2009 Wiley‐Liss, Inc.