Clinical features and outcomes of gastric variceal bleeding: retrospective Korean multicenter data

Background/AimsWhile gastric variceal bleeding (GVB) is not as prevalent as esophageal variceal bleeding, it is reportedly more serious, with high failure rates of the initial hemostasis (>30%), and has a worse prognosis than esophageal variceal bleeding. However, there is limited information regarding hemostasis and the prognosis for GVB. The aim of this study was to determine retrospectively the clinical outcomes of GVB in a multicenter study in Korea.MethodsThe data of 1,308 episodes of GVB (males:females=1062:246, age=55.0±11.0 years, mean±SD) were collected from 24 referral hospital centers in South Korea between March 2003 and December 2008. The rates of initial hemostasis failure, rebleeding, and mortality within 5 days and 6 weeks of the index bleed were evaluated.ResultsThe initial hemostasis failed in 6.1% of the patients, and this was associated with the Child-Pugh score [odds ratio (OR)=1.619; P<0.001] and the treatment modality: endoscopic variceal ligation, endoscopic variceal obturation, and balloon-occluded retrograde transvenous obliteration vs. endoscopic sclerotherapy, transjugular intrahepatic portosystemic shunt, and balloon tamponade (OR=0.221, P<0.001). Rebleeding developed in 11.5% of the patients, and was significantly associated with Child-Pugh score (OR=1.159, P<0.001) and treatment modality (OR=0.619, P=0.026). The GVB-associated mortality was 10.3%; mortality in these cases was associated with Child-Pugh score (OR=1.795, P<0.001) and the treatment modality for the initial hemostasis (OR=0.467, P=0.001).ConclusionsThe clinical outcome for GVB was better for the present cohort than in previous reports. Initial hemostasis failure, rebleeding, and mortality due to GVB were universally associated with the severity of liver cirrhosis

Effect of elevated atmospheric CO2 concentration on growth and leaf litter decomposition of Quercus acutissima and Fraxinus rhynchophylla.

The atmospheric carbon dioxide (CO2) level is expected to increase substantially, which may change the global climate and carbon dynamics in ecosystems. We examined the effects of an elevated atmospheric CO2 level on the growth of Quercus acutissima and Fraxinus rhynchophylla seedlings. We investigated changes in the chemical composition of leaf litter, as well as litter decomposition. Q. acutissima and F. rhynchophylla did not show differences in dry weight between ambient CO2 and enriched CO2 treatments, but they exhibited different patterns of carbon allocation, namely, lower shoot/root ratio (S/R) and decreased specific leaf area (SLA) under CO2-enriched conditions. The elevated CO2 concentration significantly reduced the nitrogen concentration in leaf litter while increasing lignin concentrations and carbon/nitrogen (C/N) and lignin/N ratios. The microbial biomass associated with decomposing Q. acutissima leaf litter was suppressed in CO2 enrichment chambers, while that of F. rhynchophylla was not. The leaf litter of Q. acutissima from the CO2-enriched chambers, in contrast with F. rhynchophylla, contained much lower nutrient concentrations than that of the litter in the ambient air chambers. Consequently, poorer litter quality suppressed decomposition

Branch Wood Decomposition of Tree Species in a Deciduous Temperate Forest in Korea

Woody debris, which is supplied by branch litter, is an important component of forest ecosystems as it contains large quantities of organic matter and nutrients. We evaluated changes in branch wood dry weight and nutrient content of six common species (Fraxinus rhynchophylla, Pinus densiflora, Prunus sargentii, Quercus mongolica, Acer pseudosieboldianum, and Symplocos chinensis for. pilosa) in a deciduous temperate forest in Korea for 40 months. Branch wood disk samples 1.4–1.6 cm thick were cut, and mass loss was measured over time using the litterbag method. No significant differences in mass loss were recorded among the six tree species. Further, mass loss was negatively correlated with initial lignin concentration and positively correlated with both initial cellulose concentration and wood density for each species. Species with high wood cellulose content had high wood density while the lignin content in wood was relatively low. Accordingly, cellulose contributed to wood density, creating a relatively lower lignin content, and the decreased lignin concentration increased the wood decomposition rate

Changes in the microbial biomass C and N of the decomposing leaf litter in the microcosms.

<p>Closed circles show leaf litter obtained from the ambient air (380 ppm CO₂) chamber, and open circles represent leaf litter obtained from the elevated CO₂ (700 ppm) chamber. Bars show standard deviations (n = 4).</p

Changes in the remaining mass of the <i>Q</i>. <i>acutissima</i> (upper) and <i>F</i>. <i>rhynchophylla</i> (lower) leaf litter in the microcosms.

<p>Closed circles represent leaf litter obtained from the ambient air (380 ppm CO₂) chamber, and open circles represent that collected from the elevated CO₂ (700 ppm) chamber. Bars show standard deviations (n = 4).</p

Ordination biplot of NMDS based on the leaf litter decomposition rate of each species.

<p><b>Angles and lengths of the radiating arrows indicate the direction and strength of the relationships of the litter quality parameters.</b> Each vector's significance level was less than 0.05. Carbon (C), nitrogen (N), lignin (Lig), cellulose (Cel), soluble carbohydrate (SC), C/N (CN), lignin/N (LigN), respiration (RES), cQa (ambient CO₂ <i>Q</i>. <i>acutissima</i> group), eQa (elevated CO₂ <i>Q</i>. <i>acutissima</i> group), cFr (ambient CO₂ <i>F</i>. <i>rhynchophylla</i> group), and eFr (elevated CO₂ <i>F</i>. <i>rhynchophylla</i> group).</p

Changes in CO₂ evolution from the decomposing leaf litter in the microcosms.

<p>Closed circles represent leaf litter obtained from the ambient air (380 ppm CO₂) chamber, and open circles represent leaf litter obtained from the elevated CO₂ (700 ppm) chamber. Bars show standard deviations (n = 4).</p

Summary of the MANOVA results for the effect of elevated CO₂ on <i>Q</i>. <i>acutissima</i> and <i>F</i>. <i>rhynchophylla</i>.

<p>Summary of the MANOVA results for the effect of elevated CO₂ on <i>Q</i>. <i>acutissima</i> and <i>F</i>. <i>rhynchophylla</i>.</p

Effect of Litter Quality on Needle Decomposition for Four Pine Species in Korea

Litter decomposition involves multiple complex processes, including interactions between the physicochemical characteristics of litter species and various environmental factors. We selected four representative pine species in South Korea (Pinus densiflora Siebold &amp; Zucc., Pinus thunbergii Parl., Pinus koraiensis Siebold &amp; Zucc., and Pinus rigida Miller) to investigate the decay rate and effects of the physicochemical properties on decomposition. Needle litters were incubated in microcosms at 23 &#176;C for 280 days and retrieved four times in about 70-day intervals. The mass loss showed significant differences among the species and was higher in the order of P. densiflora (30.5%), P. koraiensis (27.8%), P. rigida (26.5%), and P. thunbergii (23.6%). The needle litter decomposition showed a negative relationship with the initial surface area, volume, density, cellulose content, and lignin/nitrogen of the litter, and a positive relationship with the initial specific leaf area (SLA), surface-area-to-volume ratio (SA/V), and water- and ethanol-soluble substances. The decomposition rate was highly affected by the physical properties of litter when compared with the initial chemical litter quality, and it was strongly influenced by SLA and SA/V. Accordingly, the physical properties of pine needle litter, especially SLA and SA/V, may be the key factors, and they could be used as predictive indices for the decomposition rate of pine tree litters