Coaxial bioprinting of a stentable and endothelialized human coronary artery-sized in vitro model.

Atherosclerosis accounts for two-thirds of deaths attributed to cardiovascular diseases, which continue to be the leading cause of mortality. Current clinical management strategies for atherosclerosis, such as angioplasty with stenting, face numerous challenges, including restenosis and late thrombosis. Smart stents, integrated with sensors that can monitor cardiovascular health in real-time, are being developed to overcome these limitations. This development necessitates rigorous preclinical trials on either animal models or in vitro models. Despite efforts being made, a suitable human-scale in vitro model compatible with a cardiovascular stent has remained elusive. To address this need, this study utilizes an in-bath bioprinting method to create a human-scale, freestanding in vitro model compatible with cardiovascular stents. Using a coaxial nozzle, a tubular structure of human coronary artery (HCA) size is bioprinted with a collagen-based bioink, ensuring good biocompatibility and suitable rheological properties for printing. We precisely replicated the dimensions of the HCA, including its internal diameter and wall thickness, and simulated the vascular barrier functionality. To simplify post-processing, a pumpless perfusion bioreactor is fabricated to culture a HCA-sized model, eliminating the need for a peristaltic pump and enabling scalability for high-throughput production. This model is expected to accelerate stent development in the future.

Bioprinting Methods for Fabricating In Vitro Tubular Blood Vessel Models.

Dysfunctional blood vessels are implicated in various diseases, including cardiovascular diseases, neurodegenerative diseases, and cancer. Several studies have attempted to prevent and treat vascular diseases and understand interactions between these diseases and blood vessels across different organs and tissues. Initial studies were conducted using 2-dimensional (2D) in vitro and animal models. However, these models have difficulties in mimicking the 3D microenvironment in human, simulating kinetics related to cell activities, and replicating human pathophysiology; in addition, 3D models involve remarkably high costs. Thus, in vitro bioengineered models (BMs) have recently gained attention. BMs created through biofabrication based on tissue engineering and regenerative medicine are breakthrough models that can overcome limitations of 2D and animal models. They can also simulate the natural microenvironment in a patient- and target-specific manner. In this review, we will introduce 3D bioprinting methods for fabricating bioengineered blood vessel models, which can serve as the basis for treating and preventing various vascular diseases. Additionally, we will describe possible advancements from tubular to vascular models. Last, we will discuss specific applications, limitations, and future perspectives of fabricated BMs.

Sensitivity of spore germination and germ tube elongation of Saccharina japonica to metal exposure.

The sensitivity of early life stages of the brown seaweed Saccharina japonica to six metals (Cd, Cu, Hg, Ni, Pb, Zn) and two waste-water samples were investigated and a new toxicity bioassay developed. The two endpoints used were spore germination and germ tube elongation with an exposure time of 24 h. Optimal test conditions determined for photon irradiance, pH, salinity and temperature were darkness, pH 8, 35‰ and 15°C, respectively. The toxicity ranking of five metals was: Hg (EC(50) of 41 and 42 µg l(-1)) > Cu (120 and 81 µg l(-1)) > Ni (2,009 and 1,360 µg l(-1)) > Zn (3,024 and 3,897 µg l(-1)) > Pb (4,760 and 4,429 µg l(-1)) > Cd (15,052 and 7,541 µg l(-1)) for germination and germ tube elongation, respectively. The sensitivities to Cd, Cu and Ni were greater in germ tube elongation than in germination process. When tested against two different waste-water samples (processed animal and printed circuit board waste-water) values of EC(50) were between 21.29 and 32.02% for germination and between 5.33 and 8.98% for germ tube elongation. Despite differences in their chemical composition, the toxic effects of waste-water samples, as indicated by EC(50) values, did not differ significantly for the same endpoints. The CV range for both germination and germ tube elongation was between 4.61 and 37.69%, indicating high levels of precision of the tests. The results compare favourably with those from more established test procedures employing micro- and macroalgae. The advantages and potential limitations of the bioassay for the assessment of anthropogenic impacts on coastal ecosystems and commercial cultivation areas in near-shore environments are discussed.

Determinants of pulmonary hypertension development in moderate or severe aortic stenosis.

Pulmonary hypertension (PHT) is not uncommon in patients with aortic stenosis (AS) and portends a dismal prognosis. We attempted to determine the prevalence of PHT and to identify contributors to its development in patients with moderate or severe AS. A total of 189 patients were enrolled. Patients were divided into two groups according to the presence or absence of PHT, with a pulmonary artery systolic pressure cutoff value of 40 mmHg. Left ventricular (LV) systolic function was assessed by global longitudinal (LV-GLS), circumferential (LV-GCS) and radial (LV-GRS) strains on top of LV ejection fraction (LV-EF). The ratio of mitral E to septal mitral annular e' velocity (E/e') was calculated to estimate LV filling pressure. Fifty patients (26.5 %) had concomitant PHT. Patients with PHT had a higher prevalence of diabetes, a lower LV-EF, a higher E/e', a larger left atrial volume index, a smaller indexed aortic valve (AV) area, and a more reduced LV-GLS (all p < 0.05). However, LV-GRS and LV-GCS were similar in patients with or without PHT. On multivariate logistic regression analysis, LV-GLS and E/e' were independently associated with PHT, whereas LV-EF and indexed AV area were not. PHT complicating moderate or severe AS is commonly found and is independently associated with systolic and diastolic dysfunction assessed by Doppler and strain imaging, but not with LV-EF.

Characteristics of products from fast pyrolysis of fractions of waste square timber and ordinary plywood using a fluidized bed reactor.

Fractions of waste square timber and waste ordinary plywood were pyrolyzed in a pyrolysis plant equipped with a fluidized bed reactor and a dual char separation system. The maximum bio-oil yield of about 65 wt.% was obtained at reaction temperatures of 450-500 °C for both feed materials. For quantitative analysis of bio-oil, the relative response factor (RRF) of each component was calculated using an effective carbon number (ECN) that was multiplied by the peak area of each component detected by a GC-FID. The predominant compounds in the bio-oils were methyl acetate, acids, hydroxyacetone, furfural, non-aromatic ketones, levoglucosan and phenolic compounds. The WOP-derived bio-oil showed it to have relatively high nitrogen content. Increasing the reaction temperature was shown to have little effect on nitrogen removal. The ash and solid contents of both bio-oils were below 0.1 wt.% due to the excellent performance of the char separation system.

Fast pyrolysis of palm kernel shells: influence of operation parameters on the bio-oil yield and the yield of phenol and phenolic compounds.

Palm kernel shells were pyrolyzed in a pyrolysis plant equipped with a fluidized-bed reactor and a char-separation system. The influence of reaction temperature, feed size and feed rate on the product spectrum was also investigated. In addition, the effect of reaction temperature on the yields of phenol and phenolic compounds in the bio-oil was examined. The maximum bio-oil yield was 48.7 wt.% of the product at 490 degrees C. The maximum yield of phenol plus phenolic compounds amounted to about 70 area percentage at 475 degrees C. The yield of pyrolytic lignin after its isolation from the bio-oil was approximately 46 wt.% based on the water and ash free oil. The pyrolytic lignin was mainly composed of phenol, phenolic compounds and oligomers of coniferyl, sinapyl and p-coumaryl alcohols. From the result of a GPC analysis, the number average molecular weight and the weight average molecular weight were 325 and 463 g/mol, respectively.

Epidural anesthesia for the patient with type IV spinal muscular atrophy -A case report-.

Spinal muscular atrophy (SMA) is a rare lower motor neurone disease in which anesthetic management is often difficult as a result of muscle weakness, hypersensitivity to non-depolarizing neuromuscular blocking agent, and succinylcholine induced hyperkalemia. We describe a 50-year-old patient with type IV SMA for synovectomy. We decided to use an epidural technique to avoid muscle relaxants and tracheal intubation. After operation, there was no exacerbation of neurologic signs and symptoms.