15 research outputs found
Coastal erosion and mangrove progradation of Southern Thailand
Approximately 60% of the southern Thai coastline used to be occupied by mangroves according to the first mangrove forest assessment in 1961. During the past three decades, these mangrove areas have been reduced to about 50% with less than 10% left on the east coast. Coastal erosion and accretion occur irregularly along the coast but an intensification of erosion has been noticed during the past decade. This study assessed the relationship between mangrove presence and changes in coastal area. Mangrove colonization rates were assessed using in situ transects and remote sensing time series. Both methods led to comparable estimates ranging between 5 and 40 m
Holocene sea levels along the Andaman Sea coast of Thailand
For the Malay-Thai Peninsula several sea-level curves for the younger Holocene, based on field evidence as well as on hydro-isostatic modelling of a far-field site, have been published. The general assumption is a rapid rise to a mid-Holocene maximum up to +5 m above present sea level, followed by a constant or oscillating regression. However, from the Andaman Sea coast of Thailand, which was affected by the 2004 tsunami, only isolated observations are available regarding Holocene sea levels. Thus, the timing and magnitude of the Holocene highstand as well as the course of the regression remain to be defined. As several palaeotsunamis could be detected in the meantime it is important to know the related sea levels as exactly as possible to judge the energy, inundation width and potential wave height of these events. Therefore, fixed biological indicators from the rocky coasts of the Phang-nga Bay and Phuket, as well as morphological indicators from beach-ridge and swale sequences along the exposed west coast (Ko Phra Thong) were studied, to gain information about the Holocene sea-level development in this region. While oyster and coral data from the Phang-nga Bay and Phuket document a Holocene maximum of +2.6 m at 5700 cal. BP, the ridge crests and swale bases in the northwest of the study area point to maximum heights of +1.5-2.0 m above the present level around 5300 years ago. During the last 3000 years, to when the largest part of the Holocene palaeotsunami deposits from Thailand was dated, relative sea levels (RSL) in both areas did not exceed +1.5 m
LectinâLike Oxidized LowâDensity Lipoprotein Receptor 1 Inhibition in Type 2 Diabetes: Phase 1 Results
Background Blockade of the lectinâlike oxidized lowâdensity lipoprotein receptorâ1 (LOXâ1) is a potentially attractive mechanism for lowering inflammatory and lipid risk in patients with atherosclerosis. This study aims to assess the safety, tolerability, and target engagement of MEDI6570, a highâaffinity monoclonal blocking antibody to LOXâ1. Methods and Results This phase 1, firstâinâhuman, placeboâcontrolled study (NCT03654313) randomized 88 patients with type 2 diabetes to receive single ascending doses (10, 30, 90, 250, or 500âmg) or multiple ascending doses (90, 150, or 250âmg once monthly for 3âmonths) of MEDI6570 or placebo. Primary end point was safety; secondary and exploratory end points included pharmacokinetics, immunogenicity, free soluble LOXâ1 levels, and change in coronary plaque volume. Mean age was 57.6/58.1âyears in the single ascending doses/multiple ascending doses groups, 31.3%/62.5% were female, and mean type 2 diabetes duration was 9.7/8.7âyears. Incidence of adverse events was similar among cohorts. MEDI6570 exhibited nonlinear pharmacokinetics, with terminal halfâlife increasing from 4.6âdays (30âmg) to 11.2âdays (500âmg), consistent with targetâmediated drug disposition. Doseâdependent reductions in mean soluble LOXâ1 levels from baseline were observed (>66% at 4âweeks and 71.61â82.96% at 10âweeks in the single ascending doses and multiple ascending doses groups, respectively). After 3 doses, MEDI6570 was associated with nonsignificant regression of noncalcified plaque volume versus placebo (â13.45âmm3 versus â8.25âmm3). Conclusions MEDI6570 was well tolerated and demonstrated doseâdependent soluble LOXâ1 suppression and a pharmacokinetic profile consistent with onceâmonthly dosing. Registration URL: https://clinicaltrials.gov/; Unique identifier: NCT03654313
Combined Mitochondrial and Nuclear Markers Revealed a Deep Vicariant History for Leopoldamys neilli, a Cave-Dwelling Rodent of Thailand
Background: Historical biogeography and evolutionary processes of cave taxa have been widely studied in temperate regions. However, Southeast Asian cave ecosystems remain largely unexplored despite their high scientific interest. Here we studied the phylogeography of Leopoldamys neilli, a cave-dwelling murine rodent living in limestone karsts of Thailand, and compared the molecular signature of mitochondrial and nuclear markers.
Methodology/Principal Findings: We used a large sampling (n = 225) from 28 localities in Thailand and a combination of mitochondrial and nuclear markers with various evolutionary rates (two intronic regions and 12 microsatellites). The evolutionary history of L. neilli and the relative role of vicariance and dispersal were investigated using ancestral range reconstruction analysis and Approximate Bayesian computation (ABC). Both mitochondrial and nuclear markers support a large-scale population structure of four main groups (west, centre, north and northeast) and a strong finer structure within each of these groups. A deep genealogical divergence among geographically close lineages is observed and denotes a high population fragmentation. Our findings suggest that the current phylogeographic pattern of this species results from the fragmentation of a widespread ancestral population and that vicariance has played a significant role in the evolutionary history of L. neilli. These deep vicariant events that occurred during Plio-Pleistocene are related to the formation of the Central Plain of Thailand. Consequently, the western, central, northern and northeastern groups of populations were historically isolated and should be considered as four distinct Evolutionarily Significant Units (ESUs).
Conclusions/Significance: Our study confirms the benefit of using several independent genetic markers to obtain a comprehensive and reliable picture of L. neilli evolutionary history at different levels of resolution. The complex genetic structure of Leopoldamys neilli is supported by congruent mitochondrial and nuclear markers and has been influenced by the geological history of Thailand during Plio-Pleistocene