Follow-up of patients with COVID-19 by the Delta variant after hospital discharge in Guangzhou, Guandong, China

ABSTRACT The B.1.617.2 (Delta) variant of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has contributed to a new increment in cases across the globe. We conducted a prospective follow-up of COVID-19 cases to explore the recurrence and potential propagation risk of the Delta variant and discuss potential explanations for the infection recurrence. A prospective, non-interventional follow-up of discharged patients who had SARS-CoV-2 infections by the Delta variant in Guangdong, China, from May 2021 to June 2021 was conducted. The subjects were asked to complete a physical health examination and undergo nucleic acid testing and antibody detection for the laboratory diagnosis of COVID-19. In total, 20.33% (25/123) of patients exhibited recurrent positive results after discharge. All patients with infection recurrence were asymptomatic and showed no abnormalities in the pulmonary computed tomography. The time from discharge to the recurrent positive testing was usually between 1-33 days, with a mean time of 9.36 days. The cycle threshold from the real-time polymerase chain reaction assay that detected the recurrence of positivity ranged from 27.48 to 39.00, with an average of 35.30. The proportion of vaccination in the non-recurrent group was higher than that in the recurrently positive group (26% vs. 4%; χ2 = 7.902; P < 0.05). Two months after discharge, the most common symptom was hair loss and 59.6% of patients had no long-term symptoms at all. It is possible for the Delta variant SARS-CoV-2 patients after discharge to show recurrent positive results of nucleic acid detection; however, there is a low risk of continuous community transmission. Both, the physical and mental quality of life of discharged patients were significantly affected. Our results suggest that it makes sense to implement mass vaccination against the Delta variant of SARS-CoV-2.

Analysis on mechanical properties and internal flow field distributions of bone scaffold by digital modeling / 医用生物力学

Objective To study mechanical properties of the bone scaffold with different structure and its internal flow field distributions, so as to provide a direct comparison and judgment on model structure and offer an effective guidance for bone scaffold structure design. Methods Bone scaffold with natural, woven and spherical pore structure were reconstructed respectively by using Pro/Engineer and Mimics. The effective elastic modulus for three kinds of scaffolds, as well as their stress distributions and internal flow field distributions under three dimensional perfusion culture system were analyzed with the finite element method. Results The bone scaffold with natural structure showed smaller effective elastic modulus, smaller peak stress and more uniform stress distributions under the same pressure. With the same initial velocity and fluid viscosity, the bone scaffold with natural structure showed smaller internal velocity, wall shear stress and wall pressure. Conclusions The bone scaffold with natural structure has better biomechanical properties, which corresponds to the design criteria of bone scaffold in bone tissue engineering.

Analysis on mechanical properties and internal flow field distributions of bone scaffold by digital modeling / 医用生物力学

Objective To study mechanical properties of the bone scaffold with different structure and its internal flow field distributions,so as to provide a direct comparison and judgment on model structure and offer an effective guidance for bone scaffold structure design.Methods Bone scaffold with natural,woven and spherical pore structure were reconstructed respectively by using Pro/Engineer and Mimics.The effective elastic modulus for three kinds of scaffolds,as well as their stress distributions and internal flow field distributions under three-dimensional perfusion culture system were analyzed with the finite element method.Results The bone scaffold with natural structure showed smaller effective elastic modulus,smaller peak stress and more uniform stress distributions under the same pressure.With the same initial velocity and fluid viscosity,the bone scaffold with natural structure showed smaller internal velocity,wall shear stress and wall pressure.Conclusions The bone scaffold with natural structure has better biomechanical properties,which corresponds to the design criteria of bone scaffold in bone tissue engineering.

Analysis on mechanical properties and internal flow field distributions of bone scaffold by digital modeling / 医用生物力学

Objective To study mechanical properties of the bone scaffold with different structure and its internal flow field distributions,so as to provide a direct comparison and judgment on model structure and offer an effective guidance for bone scaffold structure design.Methods Bone scaffold with natural,woven and spherical pore structure were reconstructed respectively by using Pro/Engineer and Mimics.The effective elastic modulus for three kinds of scaffolds,as well as their stress distributions and internal flow field distributions under three-dimensional perfusion culture system were analyzed with the finite element method.Results The bone scaffold with natural structure showed smaller effective elastic modulus,smaller peak stress and more uniform stress distributions under the same pressure.With the same initial velocity and fluid viscosity,the bone scaffold with natural structure showed smaller internal velocity,wall shear stress and wall pressure.Conclusions The bone scaffold with natural structure has better biomechanical properties,which corresponds to the design criteria of bone scaffold in bone tissue engineering.

Impact of the tissue factor pathway inhibitor gene on apoptosis in human vascular smooth muscle cells

Tissue factor pathway inhibitor (TFPI) plays a vitally important role in the blood coagulation pathway. Recent studies indicated that TFPI induces apoptosis in vascular smooth-muscle cells (VSMCs) in animals. The present study investigated whether the TFPI gene could also induce apoptosis in human vascular smooth-muscle cells (hVSMCs). Such cells were isolated from human umbilical arteries and subsequently transfected with pIRES-TFPI plasmid (2 μg/mL). MTT assaying and cell counting were applied to measure cell viability and proliferation, RT-PCR was utilized to analyze TFPI gene expression in the cells. Apoptosis was analyzed by fluorescence activated cell sorting (FACS). Several key proteins involved in apoptosis were examined through Western blotting. It was shown that TFPI gene transfer led to its increased cellular expression, with a subsequent reduction in hVSMC proliferation. Further investigation demonstrated that TFPI gene expression resulted in lesser amounts of procaspase-3, procaspase-8 and procascase-9, and an increased release of mitochondrial cytochrome c (cyt-c) into cytoplasm, thereby implying the involvement of both extrinsic and intrinsic pathways in TFPI gene-induced apoptosis in hVSMCs.

Thoracic radiotherapy in limited-stage small cell lung cancer / 国际肿瘤学杂志

The effective therapy of limited stage-small cell lung cancer( LS-SCLC) is combined chemotherapy and thoracic radiotherapy(TRT). Early thoracic irradiation is better than later one. Start of any treatment and end of radiotherapy less than 30 days is associated with improved survival in LS-SCLC patients. Concurrent chemoradiotherapy results in longer survival time than sequential and alternating chemoradiotherapy. There are no clear answers on optimal irradiation dose. Hyperfractinated irradiation may have therapeutic benefit compared with conventional irradiation.