Magnetically Controlled Capsule Endoscopy for Assessment of Antiplatelet Therapy-Induced Gastrointestinal Injury.

BACKGROUND: Gastrointestinal bleeding is the most frequent major complication of antiplatelet therapy. In patients at low bleeding risk, however, clinically overt gastrointestinal bleeding is relatively uncommon. OBJECTIVES: The authors sought to assess the effects of different antiplatelet regimens on gastrointestinal mucosal injury by means of a novel magnetically controlled capsule endoscopy system in patients at low bleeding risk. METHODS: Patients (n = 505) undergoing percutaneous coronary intervention in whom capsule endoscopy demonstrated no ulcerations or bleeding (although erosions were permitted) after 6 months of dual antiplatelet therapy (DAPT) were randomly assigned to aspirin plus placebo (n = 168), clopidogrel plus placebo (n = 169), or aspirin plus clopidogrel (n = 168) for an additional 6 months. The primary endpoint was the incidence of gastrointestinal mucosal injury (erosions, ulceration, or bleeding) at 6-month or 12-month capsule endoscopy. RESULTS: Gastrointestinal mucosal injury through 12 months was less with single antiplatelet therapy (SAPT) than with DAPT (94.3% vs 99.2%; P = 0.02). Aspirin and clopidogrel monotherapy had similar effects. Among 68 patients without any gastrointestinal injury at randomization (including no erosions), SAPT compared with DAPT caused less gastrointestinal injury (68.1% vs 95.2%; P = 0.006), including fewer new ulcers (8.5% vs 38.1%; P = 0.009). Clinical gastrointestinal bleeding from 6 to 12 months was less with SAPT than with DAPT (0.6% vs 5.4%; P = 0.001). CONCLUSIONS: Despite being at low risk of bleeding, nearly all patients receiving antiplatelet therapy developed gastrointestinal injury, although overt bleeding was infrequent. DAPT for 6 months followed by SAPT with aspirin or clopidogrel from 6 to 12 months resulted in less gastrointestinal mucosal injury and clinical bleeding compared with DAPT through 12 months. (OPT-PEACE [Optimal Antiplatelet Therapy for Prevention of Gastrointestinal Injury Evaluated by Ankon Magnetically Controlled Capsule Endoscopy]; NCT03198741).

Toward image quality assessment in optical coherence tomography (OCT) of rat kidney.

BACKGROUND: Optical coherence tomography (OCT) is a useful tool for the evaluation of structure and function of the kidney, but the image quality can be effected by many factors. OBJECTIVE: The objective of this study was to assess the image quality of different OCT systems in OCT imaging of the living kidney. METHODS: One swept-source OCT (SSOCT) of 1300 nm, one spectral domain OCT (SDOCT) of 1300 nm and another of 900 nm were used. A FeO phantom was used to establish the point spread function (PSF). Rat kidneys were imaged for image quality assessment. Light penetration in the kidney and the optical attenuation coefficient were also evaluated. The quantification of uriniferous tubules was carried out via the threshold segmentation of 3D OCT images. RESULTS: The quality of kidney images was resolution dependent. SDOCT of 900 nm showed higher peak signal-to noise ratio and dynamic range. The spatial resolution in the light field could be derived from the PSF distribution along three mutually orthogonal axes. In conjunction with the PSF, the Lucy-Richardson algorithm could improve image quality but could not reveal more microstructural information. The penetration depth of 1300 nm was deeper than that of 900 nm. The attenuation coefficient of the kidney was 29 cm-1 at 1300 nm and 50 cm-1 at 900 nm (P < 0.001). More accurate measurement of uriniferous tubules was achieved with the SDOCT-900 due to its higher resolution. CONCLUSIONS: Both SSOCT and SDOCT systems could be useful for imaging uriniferous tubules in the superficial layers of the cortex. The OCT image quality was highly correlated with the spatial resolution of OCT system.

Assessment of fatigue-related biochemical alterations in a rat swimming model under hypoxia.

It is well known that exercise-induced fatigue is exacerbated following hypoxia exposure and may arise from central and/or peripheral mechanisms. To assess the relative contribution of peripheral and central factors to exercise-induced fatigue under hypoxia, a rat model of fatigue by a bout of exhaustive swimming was established and fatigue-related biochemical changes in normoxic and severe hypoxic conditions were compared. Rats were randomly divided into four groups: normoxia resting (NR), exhaustive swimming (NE), hypoxia resting (HR) and exhaustive swimming (HE). The swimming time to exhaustion with a weight equal to 2.5% of their body weight reduced under hypoxia. There were lower blood lactate levels, lower gastrocnemius pAMPK/AMPK ratios and higher gastrocnemius glycogen contents in the HE than in the NE groups, which all suggested a lower degree of peripheral fatigue in the HE group than in the NE group. Meanwhile, there was a significant increase in striatal 3,4-dihydroxyphenylacetic acid (DOPAC) caused by exhaustive swimming under normoxia, whereas this increase was almost blunted under severe hypoxia, indicating that hypoxia might exacerbate exercise-induced central fatigue. These biochemical changes suggest that from normoxia to severe hypoxia, the relative contribution of peripheral and central factors to exercise-induced fatigue alters, and central fatigue may play a predominant role in the decline in exercise performance under hypoxia.

Altitudinal disparity in growth of Dahurian larch (Larix gmelinii Rupr.) in response to recent climate change in northeast China.

Forests are sensitive to climate change at high altitude and high latitude. Dahurian larch (Larix gmelinii Rupr.) has experienced an unprecedented forest retreat northward during the last century. Whether the response of growth to climate has dissimilar patterns at different altitudes, and what the "altitudinal trends" of forest development will be in the future, remains unclear. We dendroclimatically investigated the impacts of climate change on the growth of larch forests along an altitudinal gradient. In total, 721 trees from 25 forest stands, representing an altitudinal range from 400 to 950 m a.s.l. in the Great Xing'an Mountains, northeast China, were sampled and used to develop tree-ring width chronologies. The results suggest that warming caused a decline in larch growth at low altitude, while tree growth increased at high altitude. The growth-climate relationships indicate that October-February temperatures were positively correlated with larch growth at low- and high-altitude sites, but negatively correlated at medium-altitude sites (ca. 600-700 m a.s.l.). April-May (early spring) temperatures and October-January precipitation had positive effects on growth in general (ca. 75% of all sites). The effects of summer temperature/precipitation on larch growth at high-altitude sites were opposite to that at low-altitude sites. This change of response from significantly positive/negative correlation to significantly negative/positive correlation occurred gradually along the altitudinal gradient. The relationships varied significantly with altitude both in the case of temperature (R2 = 0.425, P < 0.001) and precipitation (R2 = 0.613, P < 0.001). The shift in response of larch forest to changes in summer temperature and precipitation occurred in the areas with a mean annual temperature of ca. -4 °C and ca. -5 °C, respectively; larch growth at temperatures lower or higher than these thresholds was limited by temperature and precipitation, respectively.