Sequential Biological Process Research Articles

Roles of Mechanosensitive Channel Piezo1 in Wound Healing and Scar Formation.

The ability to heal one's wounds is perhaps one of the most fundamental and critical of physiologic processes. This coordinated and closely regulated sequential biological process involves a variety of migratory and resident cells. The activation, modulation, balance, and control of these functions depend upon soluble mediators that activate cells and modulate their diverse functions. Recent advances have identified mechanotransduction as functionally integral in many different cell types and physiologic processes. The mechanically sensitive ion channel Pieoz1 is expressed on platelets, neutrophils, macrophages, endothelial cells, keratinocytes, and fibroblasts, all of which are principally involved in wound healing. On a cellular level, there have been great advances in our understanding of the functional role of Piezo1 mechanotransduction in cutaneous wounding. The blocking of Piezo1 has recently been shown to reduce scarring in vivo and yet, thus far, a comprehensive understanding of the roles that Piezo1 plays in in vivo wound healing remains lacking. Recognizing the ever-present and critical importance of optimal and reparative wound healing, and with the availability of new physical mechanomodulating devices, the time is ripe for gaining deeper insights into optimizing wound healing. In this review, we describe the current knowledge of Piezo1 related to wound healing.

Ion-incorporated titanium implants for staged regulation of antibacterial activity and immunoregulation-mediated osteogenesis.

Antibacterial properties and osteogenic activity are considered as two crucial factors for the initial healing and long-term survivability of orthopedic implants. For decades, various drug-loaded implants to enhance biological activities have been investigated extensively. More importantly, to control the drug release timing is equally significant due to the sequential biological processes after implantation. Hence, developing a staged regulation system on the titanium surface is practically significant. Here, we prepared TiO2 nanotubes (TiO2 NTs) on the titanium surface by anodization, followed by the incorporation of zinc (Zn) and strontium (Sr) sequentially through a hydrothermal process. Surface characterization confirmed the successful fabrication of Zn and Sr-incorporated TiO2 NTs (Zn-Sr/TiO2) on the titanium surface. The ion release results exhibited the differential releasecharacteristicof Zn and Sr, which meant the early-stage release of Zn and the long-term release of Sr. It was exactly in accord withthe biological process after implantation, laying the basis of staged regulation after implantation. Zn-Sr/TiO2 showed favorable anti-early infection properties both in vitro and in vivo. Its inhibition effect on bacterial biofilm formation was attributed to the resistance against bacteria's initial adhesion and the killing effect on planktonic bacteria. Additionally, the release of Sr could alleviate infection-induced damage via immunoregulation. The biocompatibility and osteogenic activity mediated by M2 macrophage activation were confirmed with in vitro and in vivo studies. Therefore, it exhibited great potential in staged regulation for antibacterial activity in the early stage and the M2 activation-mediated osteogenic activity in the late stage. The staged regulation process was based on the differential release of Zn and Sr to achieve the early antibacterial effect and the long-term immune-induced osteogenic activity, to prevent implant-related infection and achieve better osseointegration. These two kinds of ions played their roles synergistically and complement mutually. This work is expected to provide an innovative idea for realizing sequential regulation after implantation.

Chromatin and non-chromatin immunoprecipitations to capture protein-protein and protein-nucleic acid interactions in living cells.

Proteins are expressed from genes via sequential biological processes of transcription, mRNA processing, export and translation, and play their roles in maintaining cellular functions via interactions with proteins, DNAs or RNAs. Thus, it is important to study the protein interactions during biological processes in living cells towards understanding their mechanisms-of-action in real time. Methodologies have been developed over the years to study protein interactions in vivo. One state-of-the-art approach is formaldehyde crosslinking-based immuno- or chemi-precipitation to analyze selective as well as genome/proteome-wide interactions in living cells. It is a popular and widely used methodology for cellular analysis of the protein-protein and protein-nucleic acid interactions. Here, we describe this approach to analyze protein-protein/nucleic acid interactions in vivo.

CellDrift: inferring perturbation responses in temporally sampled single-cell data.

Cells and tissues respond to perturbations in multiple ways that can be sensitively reflected in the alterations of gene expression. Current approaches to finding and quantifying the effects of perturbations on cell-level responses over time disregard the temporal consistency of identifiable gene programs. To leverage the occurrence of these patterns for perturbation analyses, we developed CellDrift (https://github.com/KANG-BIOINFO/CellDrift), a generalized linear model-based functional data analysis method that is capable of identifying covarying temporal patterns of various cell types in response to perturbations. As compared to several other approaches, CellDrift demonstrated superior performance in the identification of temporally varied perturbation patterns and the ability to impute missing time points. We applied CellDrift to multiple longitudinal datasets, including COVID-19 disease progression and gastrointestinal tract development, and demonstrated its ability to identify specific gene programs associated with sequential biological processes, trajectories and outcomes.

Optimizing microenvironment by integrating negative pressure and exogenous electric fields via a flexible porous conductive dressing to accelerate wound healing.

Wound healing is a complex and sequential biological process that involves multiple stages. Current treatments for nonhealing or chronic wounds are unsatisfactory as they exert a single effect on one specific activity. Herein, we constructed a silver nanowire (AgNW)-based, three-dimensional (3D), porous foam dressing that is flexible and conductive. This conductive foam dressing was composed of AgNWs modified with a stable hydrophobic coating and porous polyurethane (PU), providing a skeleton to support the 3D conductive networks. The AgNWs-PU foam dressing exhibited favorable biocompatibility, outstanding electrical properties, excellent bending-compression durability, and long-term stability under wet conditions, making it suitable for wound treatment. Via the conductive foam dressing, negative pressure and exogenous wound directional electric fields (EFs) could be integrated for simultaneous implementation, and the artificial jointly constructed microenvironment promoted wound healing in a system. This novel "all-in-one" device presented intrinsic multifunctionality, including the drainage of pus and necrotic tissue, mitigation of inflammation, promotion of cell proliferation, direction of keratinocyte migration, and induction of angiogenesis. An immunohistochemical assay and western blot analysis illustrated that the angiogenesis and cell proliferation pathways in the tissue were significantly activated when this novel therapy was adopted. More importantly, the practical performance of this "all-in-one" device was demonstrated by assessment of full-thickness defect wounds in model pigs. Comparing the percentage of residual wound area after administration of traditional treatment (25.82 ± 3.52%) and the novel treatment (3.07 ± 1.23%) demonstrated the promising applications of this novel treatment in clinical wound healing.

Transcriptomic analysis reveals dynamic molecular changes in skin induced by mechanical forces secondary to tissue expansion

Tissue expansion procedures (TE) utilize mechanical forces to induce skin growth and regeneration. While the impact of quick mechanical stimulation on molecular changes in cells has been studied extensively, there is a clear gap in knowledge about sequential biological processes activated during long-term stimulation of skin in vivo. Here, we present the first genome-wide study of transcriptional changes in skin during TE, starting from 1 h to 7 days of expansion. Our results indicate that mechanical forces from a tissue expander induce broad molecular changes in gene expression, and that these changes are time-dependent. We revealed hierarchical changes in skin cell biology, including activation of an immune response, a switch in cell metabolism and processes related to muscle contraction and cytoskeleton organization. In addition to known mechanoresponsive genes (TNC, MMPs), we have identified novel candidate genes (SFRP2, SPP1, CCR1, C2, MSR1, C4A, PLA2G2F, HBB), which might play crucial roles in stretched-induced skin growth. Understanding which biological processes are affected by mechanical forces in TE is important for the development of skin treatments to maximize the efficacy and minimize the risk of complications during expansion procedures.

Hollow, Rough, and Nitric Oxide-Releasing Cerium Oxide Nanoparticles for Promoting Multiple Stages of Wound Healing.

Wound healing is a complex and sequential biological process that involves multiple stages. Although various nanomaterials are applied to accelerate the wound healing process, only a single stage is promoted during the process, lacking hierarchical stimulation. Herein, hollow CeO2 nanoparticles (NPs) with rough surface and l-arginine inside (Ah CeO2 NPs) are developed as a compact and programmable nanosystem for sequentially promoting the hemostasis, inflammation, and proliferation stages. The rough surface of Ah CeO2 NPs works as a nanobridge to rapidly closure the wounds, promoting the hemostasis stage. The hollow structure of Ah CeO2 NPs enables the multireflection of light inside particles, significantly enhancing the light harvest efficiency and electron-hole pair abundance. Simultaneously, the porous shell of Ah CeO2 NPs facilitates the electron-hole separation and reactive oxygen species production, preventing wound infection and promotion wound healing during the inflammation stage. The enzyme mimicking property of Ah CeO2 NPs can alleviate the oxidative injury in the wound, and the released l-arginine can be converted into nitric oxide (NO) under the catalysis of inducible NO synthase, both of which promote the proliferation stage. A series of in vitro and in vitro biological assessments corroborate the effectiveness of Ah CeO2 NPs in the wound healing process.

Summary of advances in the research of wound therapy

Wound healing is a complex and sequential biological process involving various cells and factors under body's regulation. Appropriate interventions play positive roles in promoting effective wound healing and improving healing quality. In the clinical practice, there are many new instruments, dressings, and drugs developed for wound care, including antibacterial dressings, wet dressings, precise debridement, negative pressure wound therapy, cytokines/growth factors, and dermal substitutes, which provide revolutionary means for wound treatment. This article summarizes the effective or mature methods in wound care, providing theoretical and practical basis for choosing appropriate treatment methods in different stages of wound.

Sequential biological process for molybdenum extraction from hydrodesulphurization spent catalyst

Spent catalyst bioleaching with Acidithiobacillus ferrooxidans has been widely studied and low Mo leaching has often been reported. This work describes an enhanced extraction of Mo via a two stage sequential process for the bioleaching of hydrodesulphurization spent catalyst containing Molybdenum, Nickel and, Aluminium. In the first stage, two-step bioleaching was performed using Acidithiobacillus ferrooxidans, and achieved 89.4% Ni, 20.9% Mo and 12.7% Al extraction in 15 days. To increase Mo extraction, the bioleached catalyst was subjected to a second stage bioleaching using Escherichia coli, during which 99% of the remaining Mo was extracted in 25 days. This sequential bioleaching strategy selectively extracted Ni in the first stage and Mo in the second stage, and is a more environmentally friendly alternative to sequential chemical leaching with alkaline reagents for improved Mo extraction. Kinetic modelling to establish the rate determining step in both stages of bioleaching showed that in the first stage, Mo extraction was chemical reaction controlled whereas in the subsequent stage, product layer diffusion model provided the best fit.

Hygienization performances of innovative sludge treatment solutions to assure safe land spreading.

The present research aims at the evaluation of the hygienization performances of innovative sludge treatment processes applied for the separated treatment of secondary sludge. Namely, two digestion pretreatments (sonication and thermal hydrolysis) and two sequential biological processes (mesophilic/thermophilic and anaerobic/aerobic digestion) were compared to the mesophilic (MAD) and thermophilic anaerobic digestion (TAD). Microbial indicators (Escherichia coli, somatic coliphages and Clostridium perfringens spores) and pathogens (Salmonella and enteroviruses), which show different resistances to treatment processes, were monitored in untreated and treated sludge. Overall, microbial load in secondary sludge was shown to be similar or lower than previously reported in literature for mixed sludge. Notably, the anaerobic/aerobic digestion process increased the removal of E. coli and somatic coliphages compared to the simple MAD and always achieved the hygienization requirement (2-log-unit removal of E. coli) proposed by EU Commission in the 3rd Working Document on sludge (April 2000) for the use of treated sludges in agriculture with restriction on their application. The microbial quality limits for the unrestricted use of sludge in agriculture (no Salmonella in 50 g wet weight (WW) and E. coli <500 CFU/g) were always met when thermal digestion or pretreatment was applied; however, the required removal level (6-log-unit removal of E. coli) could not be assessed due to the low level of this microorganism in raw sludge. Observed levels of indicator removal showed a higher resistance of viral particles to thermal treatment compared with bacterial cells and confirmed the suitability of somatic coliphages as indicators in thermal treatment processes.

HIV, Inflammation, and Calcium in Atherosclerosis

Atherosclerosis is consistently higher among the HIV-positive patients, with or without treatment, than among the HIV-negative population. Risk factors linked to atherosclerotic cardiovascular disease in HIV infection are both traditional and HIV specific although the underlying mechanisms are not fully delineated. Three key sequential biological processes are postulated to accelerate progression of atherosclerosis in the context of HIV: (1) inflammation, (2) transformation of monocytes to macrophages and then foam cells, and (3) apoptosis of foam cells leading to plaque development through Ca(2+)-dependent endoplasmic reticulum stress. These proatherogenic mechanisms are further affected when HIV interacts with the genes involved in various phases within this network.

PAPER PRESENTED AT INTERNATIONAL WORKSHOP ON INCREASING WHEAT YIELD POTENTIAL, CIMMYT, OBREGON, MEXICO, 20–24 MARCH 2006 Structural equation modelling for studying genotype×environment interactions of physiological traits affecting yield in wheat

In plant physiology and breeding, it is important to understand the causes of genotype×environment interactions (GEIs) of complex traits such as grain yield. It is difficult to study the underlying sequential biological processes of such traits, their components and other intermediate traits, as well as the main environmental factors affecting those processes. The structural equation models (SEMs) used in the present study allow the external and internal factors affecting GEI of various traits and their interrelations to be accounted for. The study included 86 wheat genotypes derived from three different crosses and evaluated over 3 years. Several attributes, as well as grain yield and yield components, were measured during five crop development stages. Environmental data for the five development stages were averaged. The SEM approach facilitated comprehensive understanding of GEI effects among the different traits, and decomposed the total effects of grain yield components and cross-product covariates on grain yield GEI into direct and indirect effects. External climatic variables were related mostly to main final yield components, and only more intermediate endogenous variables, such as spikes/m2, were affected by minimum temperature and radiation in the early stages of plant development.

Basal B-cell receptor signaling in B lymphocytes: mechanisms of regulation and role in positive selection, differentiation, and peripheral survival.

B-cell development is a highly ordered multistep process dependent upon signals generated by the pre-B and B-cell antigen receptor (BCR). BCR signals drive maturation of the B cell by integrating a number of parallel and sequential biological processes that result in generation of fully immunocompetent B cells. Among these biological processes are positive selection through several developmental checkpoints, negative selection of potentially self-reactive B cells, and activation of the mature B cell. In addition, recent studies have shown that developing and mature B cells rely on the constant activity of the BCR for their continued survival. Ligand (antigen)-dependent and -independent mechanisms of BCR signaling have been proposed, but their specific contributions to B-cell maturation and differentiation in the bone marrow and periphery are not completely clear. We discuss here a model, whereby ligand-independent basal BCR activity would be sufficient to trigger B-cell development through to the mature stage. However, long-term survival and formation of specific mature B-cell populations may be dependent on ligand-receptor interactions.

Bioactive interleukin-8 is expressed in wounds and enhances wound healing.

Wound healing is a sequential biological process that involves the integration of chemotaxis of neutrophils, mitosis and migration of keratinocytes, and remodeling of the scar, all of which are regulated by specific soluble mediators. To modulate wound healing specific mediators have to be identified and functionally characterized. Therefore we addressed this study on the polymorphonuclear leukocyte (PMN) attractant interleukin-8 (IL-8) and its function in epidermal wound healing. Peptide purification, bioassays for PMN chemotaxis, and sequential IL-8 measurements were performed on human wound fluid from burn blisters and skin graft donor sites. Histology for IL-8 immunoreactivity was included. In vitro human keratinocytes were assayed for proliferation, migration, and integrin expression after IL-8 treatment. Wounding experiments with topical IL-8 were performed in a chimeric mouse model. IL-8 was found to be the major bioactive chemoattractant for PMNs in human blister and skin graft donor site wound fluids (mean levels ranging from 173 ng/ml Postoperative Day (POD) 1 to 2130 ng/ml (POD 5)). Released intracellular epidermal IL-8 immunoreactivity at the wound edge was considered as an immediate source of IL-8 while NH(2)-terminal analysis revealed the 77-amino-acid residue form as a second source of IL-8 possibly PMN derived. In vitro experiments on the effect of recombinant human (rh) IL-8 on keratinocyte proliferation revealed a rise in cell number (4.8-fold, ED(50) = 0.6 ng/ml), which was accompanied by an increase in cells in S phase and overexpression of the integrin subunit alpha6. In vivo topically applied IL-8 (1 microg/ml) on human skin grafts in a chimeric mouse model enhanced reepithelialization in IL-8 treated animals over controls due to elevated numbers of mitotic keratinocytes. Wound contraction was significantly diminished by topical IL-8. These results indicate the sequential function of endogenous IL-8 in all phases of human wound healing. Topical IL-8 may be useful in impaired wound healing.