SPARCL1 as a biomarker of maladaptive right ventricular remodelling in pulmonary hypertension

Abstract

Aim: This study assessed the utility of SPARC-like protein 1 (SPARCL1) as a biomarker of maladaptive right ventricular (RV) function in patients with pulmonary hypertension (PH).

Methods: In this prospective study, we examined SPARCL1 levels in 105 patients with adaptive (n?=?34) and maladaptive RV (n?=?32) pressure overload caused by PH, dilated cardiomyopathy (DCM, n?=?18) with LVEF < 35% and preserved RV function and controls without LV or RV abnormalities (n?=?21).

Results: The median SPARCL1 concentration in patients with maladaptive RV function was higher than in those with adaptive RV function (p?<?0.01), DCM (p?<?0.001) or controls (p?<?0.001). Patients with adaptive RV function had higher SPARCL1 concentrations than controls (p?<?0.05), whereas there was no difference between adaptive RV and DCM. SPARCL1 showed good predictive power for maladaptive RV (AUC 0.77, p?<?0.001) with an optimal cut-off value of 9.66?ng/ml. The TAPSE/PASP ratio was the only independent predictor of SPARCL1?≥?9.66?ng/ml in multivariable logistic regression analysis.

Conclusion: SPARCL1 shows potential as novel biomarker of RV pathological remodelling and is associated with RV maladaptation and ventriculoarterial uncoupling in PH.     

In vitro study of platelet concentrate preparations from whole blood using N-(2-mercaptopropionyl)-glycine

The sulfhydryl group containing drug N-(2-mercaptopropionyl)-glycine (MPG) which inhibits platelet aggregation in a reversible manner permits to prepare platelet concentrates in non-siliconized glass containers at pH 7.4. Resuspension of platelets is possible immediately after centrifugation. In vitro platelets tests were carried out after washing out the MPG in MPG-free plasma. Thereafter, no inhibitory effects on platelet functions were found. Platelets concentrated in presence of MPG were significantly better with respect to yield, maintenance of discoid shape, aggregability, and hypotonic shock response compared with control platelets concentrated in absence of MPG.     

The role of the actin status in platelet behaviour

The status of platelet actin has been studied analytically by the DNase-I inhibition assay. Exposure of platelets to diamide, which oxidizes sulphydryl groups, results in an increase of filamentous actin. Neutralization of the effect of diamide by addition of 2-mercaptopropionylglycine (2-MPG) or washing out the excess of diamide is associated with a normalization of the cellular actin status. These findings strongly suggest that the redox state of platelets is somehow involved in the process of actin polymerization. Alterations of the redox state in metabolically altered platelets could therefore account for changes in the G- to F-actin equilibrium. In the thrombin-induced actin polymerization the redox state of the cell seems to be not involved, since 2-MPG preincubation of platelets (1.25 mM, 30 min) does not inhibit the filament assembly.     

The use of N-(2-mercaptopropionyl)-glycine (MPG) for preparation and storage of platelets

The SH group containing drug MPG which inhibits platelet aggregation in a reversible manner was used as a cytoprotective substance in some experiments on preparation and storage of human platelets for transfusion. In vitro (n = 6): concentration, morphology score, HSR and aggregation of stored platelets were measured after simulating in vitro the post transfusional conditions by resuspension of stored platelets in fresh drawn plasma (pH 7.4, 37 degrees C). In vivo (n = 2): Autologous platelets stored for 48 h at 22 degrees C were labelled with 111In and retransfused. The results obtained from platelets prepared and stored in plasma containing MPG were compared with those obtained from control platelets without MPG.     

Regional variation in nonmedical factors affecting family physicians' decisions about referral for consultation

OBJECTIVE: To determine whether there is regional variation in environmental (non-medical) factors affecting referral decisions of family physicians (FPs). DESIGN: Cross-sectional interview survey. SETTING: Nova Scotia. PARTICIPANTS: A random sample of 125 FPs grouped into 1 of 5 functionally defined geographic regions of Nova Scotia (25 in each group). Groupings were based on access to general hospital beds through active staff hospital appointments or to specialist consultants in the community, or both. Participants were personally interviewed on site. No physician refused an interview. In 9 cases the physician indicated that he or she did not fit the profile of the assigned group; the physician was excluded from the study and the next doctor on the list was substituted. OUTCOME MEASURES: The questionnaire was designed to test several hypotheses about factors known to potentially influence decisions about referral. Geographic differences in factors affecting referral and in decisions about 5 hypothetical cases were assessed with the use of significance tests for proportions that were sensitive to specific orders across groups. RESULTS: Three factors affecting referral showed unequivocal variation across the 5 groups. Access to hospital facilities and remoteness from specialist care, leading to local styles of practice or treatment policies, and the FP''s relationship with specialist consultants appeared to be important nonmedical factors affecting referral decisions. For similar case scenarios the physicians living in rural areas would refer only half as often overall as those living in urban areas with tertiary care hospitals; for some cases, such as a severe asthma attack, the difference was more than 7-fold. CONCLUSIONS: Significant differences in nonmedical factors affecting referral, and in referral decisions about hypothetical cases, were found between the groups of FPs. Differences in access to resources, creating local styles of practice, appeared to explain most of the variation. The results may account for previously observed differences in actual rates of referral for these particular groups.     

Homospermidine in transgenic tobacco results in considerably reduced spermidine levels but is not converted to pyrrolizidine alkaloid precursors

Homospermidine synthase is the first specific enzyme in the biosynthesis of pyrrolizidine alkaloids. Whereas the substrates putrescine and spermidine are part of the highly dynamic polyamine pool of plants, the product homospermidine is incorporated exclusively into the necine base moiety of pyrrolizidine alkaloids. Recently, the gene encoding homospermidine synthase has been shown to have been recruited several times independently during angiosperm evolution by the duplication of the gene encoding deoxyhypusine synthase. To test whether high levels of homospermidine suffice for conversion, at least in traces, to precursors of pyrrolizidine alkaloids, transgenic tobacco plants were generated expressing homospermidine synthase. Analyses of the polyamine content revealed that, in the transgenic plants, about 80% of spermidine was replaced by homospermidine without any conspicuous modifications of the phenotype. Tracer-feeding experiments and gas chromatographic analyses suggested that these high levels of homospermidine were not sufficient to explain the formation of alkaloid precursors. These results are discussed with respect to current models of pathway evolution.     

The Late Eocene ‘Whiskey Creek’ methane-seep deposit (western Washington State)

The Late Eocene ‘Whiskey Creek’ deposit (Pysht Formation, Olympic Penisula, Washington State) formed at a methane-seep. Early diagenetic micrites and aragonite cement have δ¹³C values as low as −36‰ indicating that the seepage fluids contained methane. With respect to micrite samples, low δ¹³C values correlate with relatively high δ¹³O values andvice versa. Ongoing micrite formation after the cessation of the seepage during increased burial might have altered the isotopic composition of the microcrystalline carbonates toward lower δ¹³O values and higher δ¹³C values. Alternatively, the trend in isotope values may reflect a change in the composition of seepage fluids. The principal difference between these scenarios is the duration of seepage with respect to micrite formation. Two petrographically similar varieties of blocky calcite spar are related to different carbonate sources. The δ¹³C values range from −32 to −29‰ for one type of blocky spar and are either the result of methane oxidation or indicate thermal decarboxylation of organic matter. Low δ¹⁸O values are in favour of the latter. For the other type of spar, δ¹³C values as high as +6‰ indicate carbonate formation within the zone of methanogensis. The ‘Whiskey Creek’ limestone exhibits a chaotic fabric produced by a variety of processes, including bioturbation, concretionary carbonate formation, earlyin situ brecciation, carbonate corrosion, and late fracturing of the rock. Two varieties of micrite aggregates are responsible for the nodular fabric of the limestone. Smoothly-shaped pyritiferous micrite nodules are of diagenetic origin and formed in a manner similar to that which produces carbonate concretions. Apart from being induced by anaerobic oxidation of methane, their formation is proposed to be linked to iron reduction and sulphide formation. The second, dominant variety is represented by irregularly-shaped, nodular to angular micrite aggregates surrounded by massive rims of pyrite, resulting from carbonate corrosion. A pure, fluorescent seam-micrite, constructive in origin, lines cavities or surrounds micritic aggregates.     

A kinetic study of the genetic control of hemopoietic progenitor cells assayed in culture and in vivo

The kinetics of growth of bone marrow cells from normal or genetically anemic mice (Sl/Sl^d and W/W^v) were studied in irradiated normal and genetically anemic hosts. The parameters followed included total cellularity, the number of peroxidase positive cells, and the number of cells capable of forming colonies in vivo (CFU-S) or in culture (CFU-C). The results of these experiments demonstrate that W and Sl defects alter the growth of CFU-C and peroxidase-positive cells to a modest degree; that the defects are more obvious when studied in spleen rather than in bone marrow; and that there is no additivity of W and Sl defects. Nineteen irradiated recipients of marrow from W/W^v mice were studied after three to six months. Of these, 18 showed host-type erythrocytes, while in one mouse the erythrocytes had the size distribution of W/W^v cells. This finding indicated that occasionally genetically defective stem cells may repopulate irradiated hosts.