Intraoperative bioprinting of human adipose-derived stem cells and extra-cellular matrix induces hair follicle-like downgrowths and adipose tissue formation during full-thickness craniomaxillofacial skin reconstruction

Craniomaxillofacial (CMF) reconstruction is a challenging clinical dilemma. It often necessitates skin replacement in the form of autologous graft or flap surgery, which differ from one another based on hypodermal/dermal content. Unfortunately, both approaches are plagued by scarring, poor cosmesis, inadequate restoration of native anatomy and hair, alopecia, donor site morbidity, and potential for failure. Therefore, new reconstructive approaches are warranted, and tissue engineered skin represents an exciting alternative. In this study, we demonstrated the reconstruction of CMF full-thickness skin defects using intraoperative bioprinting (IOB), which enabled the repair of defects via direct bioprinting of multiple layers of skin on immunodeficient rats in a surgical setting. Using a newly formulated patient-sourced allogenic bioink consisting of both human adipose-derived extracellular matrix (adECM) and stem cells (ADSCs), skin loss was reconstructed by precise deposition of the hypodermal and dermal components under three different sets of animal studies. adECM, even at a very low concentration such as 2 % or less, has shown to be bioprintable via droplet-based bioprinting and exhibited de novo adipogenic capabilities both in vitro and in vivo. Our findings demonstrate that the combinatorial delivery of adECM and ADSCs facilitated the reconstruction of three full-thickness skin defects, accomplishing near-complete wound closure within two weeks. More importantly, both hypodermal adipogenesis and downgrowth of hair follicle-like structures were achieved in this two-week time frame. Our approach illustrates the translational potential of using human-derived materials and IOB technologies for full-thickness skin loss.

Synergistic coupling between 3D bioprinting and vascularization strategies

Three-dimensional (3D) bioprinting offers promising solutions to the complex challenge of vascularization in biofabrication, thereby enhancing the prospects for clinical translation of engineered tissues and organs. While existing reviews have touched upon 3D bioprinting in vascularized tissue contexts, the current review offers a more holistic perspective, encompassing recent technical advancements and spanning the entire multistage bioprinting process, with a particular emphasis on vascularization. The synergy between 3D bioprinting and vascularization strategies is crucial, as 3D bioprinting can enable the creation of personalized, tissue-specific vascular network while the vascularization enhances tissue viability and function. The review starts by providing a comprehensive overview of the entire bioprinting process, spanning from pre-bioprinting stages to post-printing processing, including perfusion and maturation. Next, recent advancements in vascularization strategies that can be seamlessly integrated with bioprinting are discussed. Further, tissue-specific examples illustrating how these vascularization approaches are customized for diverse anatomical tissues towards enhancing clinical relevance are discussed. Finally, the underexplored intraoperative bioprinting (IOB) was highlighted, which enables the direct reconstruction of tissues within defect sites, stressing on the possible synergy shaped by combining IOB with vascularization strategies for improved regeneration.

Intraoperative Bioprinting of Human Adipose-derived Stem cells and Extra-cellular Matrix Induces Hair Follicle-Like Downgrowths and Adipose Tissue Formation during Full-thickness Craniomaxillofacial Skin Reconstruction

Craniomaxillofacial (CMF) reconstruction is a challenging clinical dilemma. It often necessitates skin replacement in the form of autologous graft or flap surgery, which differ from one another based on hypodermal/dermal content. Unfortunately, both approaches are plagued by scarring, poor cosmesis, inadequate restoration of native anatomy and hair, alopecia, donor site morbidity, and potential for failure. Therefore, new reconstructive approaches are warranted, and tissue engineered skin represents an exciting alternative. In this study, we demonstrated the reconstruction of CMF full-thickness skin defects using intraoperative bioprinting (IOB), which enabled the repair of defects via direct bioprinting of multiple layers of skin on immunodeficient rats in a surgical setting. Using a newly formulated patient-sourced allogenic bioink consisting of both human adipose-derived extracellular matrix (adECM) and stem cells (ADSCs), skin loss was reconstructed by precise deposition of the hypodermal and dermal components under three different sets of animal studies. adECM, even at a very low concentration such as 2% or less, has shown to be bioprintable via droplet-based bioprinting and exhibited de novo adipogenic capabilities both in vitro and in vivo . Our findings demonstrate that the combinatorial delivery of adECM and ADSCs facilitated the reconstruction of three full-thickness skin defects, accomplishing near-complete wound closure within two weeks. More importantly, both hypodermal adipogenesis and downgrowth of hair follicle-like structures were achieved in this two-week time frame. Our approach illustrates the translational potential of using human-derived materials and IOB technologies for full-thickness skin loss.

High-throughput bioprinting of the nasal epithelium using patient-derived nasal epithelial cells

Progenitor human nasal epithelial cells (hNECs) are an essential cell source for the reconstruction of the respiratory pseudostratified columnar epithelium composed of multiple cell types in the context of infection studies and disease modeling. Hitherto, manual seeding has been the dominant method for creating nasal epithelial tissue models through biofabrication. However, this approach has limitations in terms of achieving the intricate three-dimensional (3D) structure of the natural nasal epithelium. 3D bioprinting has been utilized to reconstruct various epithelial tissue models, such as cutaneous, intestinal, alveolar, and bronchial epithelium, but there has been no attempt to use of 3D bioprinting technologies for reconstruction of the nasal epithelium. In this study, for the first time, we demonstrate the reconstruction of the nasal epithelium with the use of primary hNECs deposited on Transwell inserts via droplet-based bioprinting (DBB), which enabled high-throughput fabrication of the nasal epithelium in Transwell inserts of 24-well plates. DBB of progenitor hNECs ranging from one-tenth to one-half of the cell seeding density employed during the conventional cell seeding approach enabled a high degree of differentiation with the presence of cilia and tight-junctions over a 4 weeks air-liquid interface culture. Single cell RNA sequencing of these cultures identified five major epithelial cells populations, including basal, suprabasal, goblet, club, and ciliated cells. These cultures recapitulated the pseudostratified columnar epithelial architecture present in the native nasal epithelium and were permissive to respiratory virus infection. These results denote the potential of 3D bioprinting for high-throughput fabrication of nasal epithelial tissue models not only for infection studies but also for other purposes, such as disease modeling, immunological studies, and drug screening.

High-Throughput Bioprinting of the Nasal Epithelium using Patient-derived Nasal Epithelial Cells

Human nasal epithelial cells (hNECs) are an essential cell source for the reconstruction of the respiratory pseudostratified columnar epithelium composed of multiple cell types in the context of infection studies and disease modeling. Hitherto, manual seeding has been the dominant method for creating nasal epithelial tissue models. However, the manual approach is slow, low-throughput and has limitations in terms of achieving the intricate 3D structure of the natural nasal epithelium in a uniform manner. 3D Bioprinting has been utilized to reconstruct various epithelial tissue models, such as cutaneous, intestinal, alveolar, and bronchial epithelium, but there has been no attempt to use of 3D bioprinting technologies for reconstruction of the nasal epithelium. In this study, for the first time, we demonstrate the reconstruction of the nasal epithelium with the use of primary hNECs deposited on Transwell inserts via droplet-based bioprinting (DBB), which enabled high-throughput fabrication of the nasal epithelium in Transwell inserts of 24-well plates. DBB of nasal progenitor cells ranging from one-tenth to one-half of the cell seeding density employed during the conventional cell seeding approach enabled a high degree of differentiation with the presence of cilia and tight-junctions over a 4-week air-liquid interface culture. Single cell RNA sequencing of these cultures identified five major epithelial cells populations, including basal, suprabasal, goblet, club, and ciliated cells. These cultures recapitulated the pseudostratified columnar epithelial architecture present in the native nasal epithelium and were permissive to respiratory virus infection. These results denote the potential of 3D bioprinting for high-throughput fabrication of nasal epithelial tissue models not only for infection studies but also for other purposes such as disease modeling, immunological studies, and drug screening.

Comparison ofin-situversusex-situdelivery of polyethylenimine-BMP-2 polyplexes for rat calvarial defect repair via intraoperative bioprinting

Gene therapeutic applications combined with bio- and nano-materials have been used to address current shortcomings in bone tissue engineering due to their feasibility, safety and potential capability for clinical translation. Delivery of non-viral vectors can be altered using gene-activated matrices to improve their efficacy to repair bone defects.Ex-situandin-situdelivery strategies are the most used methods for bone therapy, which have never been directly compared for their potency to repair critical-sized bone defects. In this regard, we first time explore the delivery of polyethylenimine (PEI) complexed plasmid DNA encoding bone morphogenetic protein-2 (PEI-pBMP-2) using the two delivery strategies,ex-situandin-situdelivery. To realize these gene delivery strategies, we employed intraoperative bioprinting (IOB), enabling us to 3D bioprint bone tissue constructs directly into defect sites in a surgical setting. Here, we demonstrated IOB of an osteogenic bioink loaded with PEI-pBMP-2 for thein-situdelivery approach, and PEI-pBMP-2 transfected rat bone marrow mesenchymal stem cells laden bioink for theex-situdelivery approach as alternative delivery strategies. We found thatin-situdelivery of PEI-pBMP-2 significantly improved bone tissue formation compared toex-situdelivery. Despite debates amongst individual advantages and disadvantages ofex-situandin-situdelivery strategies, our results ruled in favor of thein-situdelivery strategy, which could be desirable to use for future clinical applications.

miRNA induced 3D bioprinted-heterotypic osteochondral interface

The engineering of osteochondral interfaces remains a challenge. MicroRNAs (miRs) have emerged as significant tools to regulate the differentiation and proliferation of osteogenic and chondrogenic formation in the human musculoskeletal system. Here, we describe a novel approach to osteochondral reconstruction based on the three-dimensional (3D) bioprinting of miR-transfected adipose-derived stem cell (ADSC) spheroids to produce a heterotypic interface that addresses the intrinsic limitations of the traditional approach to inducing zonal differentiation via the use of diffusible cytokines. We evaluated the delivery of miR-148b for osteogenic differentiation and the codelivery of miR-140 and miR-21 for the chondrogenic differentiation of ADSC spheroids. Our results demonstrated that miR-transfected ADSC spheroids exhibited upregulated expression of osteogenic and chondrogenic differentiation related gene and protein markers, and enhanced mineralization and cell proliferation compared to spheroids differentiated using a commercially-available differentiation medium. Upon confirmation of the osteogenic and chondrogenic potential of miR-transfected ADSC spheroids, using aspiration-assisted bioprinting, these spheroids were 3D bioprinted into a dual-layer heterotypic osteochondral interface with a stratified arrangement of distinct osteogenic and chondrogenic zones. The proposed approach holds great promise for the biofabrication of stratified tissues, not only for the osteochondral interfaces presented in this work, but also for other composite tissues and tissue interfaces, such as, but not limited to, the bone-tendon-muscle interface and craniofacial tissues.

Electrohydrodynamic-direct-printed cell-laden microfibrous structure using alginate-based bioink for effective myotube formation

In this study, a fully aligned microfibrous structure fabricated using fibrin-assisted alginate bioink and electrohydrodynamic direct-printing was proposed for skeletal muscle tissue engineering. To safely construct the aligned alginate/fibrin microfibrous structure laden with myoblasts or endothelial cells, various printing conditions, such as an applied electric field, distance between the nozzle and target, and nozzle moving speed, were selected appropriately. Furthermore, to accelerate the formation of myotubes more efficiently, the alginate/fibrin bioink with vascular endothelial cells was co-printed into a spatially patterned structure within a myoblast-laden structure. The myoblast-laden structure co-cultured with endothelial cells presented fully aligned myotube formation and significantly greater myogenic differentiation compared to the myoblast-laden structure without the endothelial cells owing to the more abundant secretion of angiogenic cytokines. Also, when adipose stem cell- and endothelial cell-laden fibrous structure was implanted in a mouse volumetric muscle loss model, accelerated volumetric muscle repair was observed compared to the defect model. Based on the results, this study demonstrates an alginate-based bioink and new bio-fabricating method to obtain microfibrous cell-laden alginate/fibrin structures with mechanically stable and topographical cues. The proposed method can provide a myoblast/endothelial cell-laden fibrous alginate structure to efficiently induce engineering of skeletal muscle tissue, which could be used in muscle-on-a-chip or recovering structures of volumetric muscle defects.

An in vitro model using spheroids-laden nanofibrous structures for attaining high degree of myoblast alignment and differentiation

A spheroid is an aggregation of single cells with structural and functional characteristics similar to those of 3D native tissues, and it has been utilized as one of the typical in vitro three-dimensional (3D) cell models. Scaffold-free spheroids provide outstanding reflection of tissue complexity in a 3D in vivo-like environment, but they can neither fabricate realistic macroscale 3D complex structures without avoiding necrosis nor receive direct external stimuli (i.e., stimuli from mechanical or topographical cues). Here, we propose a spheroid-laden electrospinning process to obtain in vitro model achieved using the synergistic effect of the unique bioactive components provided by the spheroids and stimulating effects provided by the aligned nanofibers.

Methods: To show the functional activity of the spheroid-laden structures, we used myoblast-spheroids to obtain skeletal muscle, comprising highly aligned myotubes, utilizing an uniaxially arranged topographical cue. The spheroid-electrospinning was used to align spheroids directly by embedding them in aligned alginate nanofibers, which were controlled with various materials and processing parameters.

Results: The spheroids laden in the alginate nanofibers showed high cell viability (>90%) and was compared with that of a cell-laden alginate nanofiber that was electrospun with single cells. Consequently, the spheroids laden in the aligned nanofibers showed a significantly higher degree of myotube formation and maturation.

Conclusion: Results suggested that the in vitro model using electrospun spheroids could potentially be employed to understand myogenic responses for various in vitro drug tests.

Pseudophoenix ekmanii (Arecaceae) seeds at suboptimal temperature show reduced imbibition rates and enhanced expression of genes related to germination inhibition

Pseudophoenix ekmanii is a critically endangered palm species that can be found in the southeast of the Dominican Republic. The temperatures to which P. ekmanii seeds are exposed upon dispersal range from 32 to 23 °C (max and min) and can reach a low of approximately 20 °C in January. Our aim was to analyse the effect of suboptimal (20 °C) and optimal (30 °C) germination temperature on seed imbibition, moisture content, embryo growth and gene expression patterns in this tropical palm species. Seed imbibition was tracked using whole seeds, while moisture content was assessed for individual seed sections. Embryo and whole seed size were measured before and after full imbibition. For transcriptome sequencing, mRNA was extracted from embryo tissues only and the resulting reads were mapped against the Elaeis guineensis reference genome. Differentially expressed genes were identified after statistical analysis and subsequently probed for enrichment of Gene Ontology categories 'Biological process' and 'Cellular component'. Our results show that prolonged exposure to 20 °C slows whole seed and embryo imbibition and causes germination to be both delayed and inhibited. Embryonic transcriptome patterns associated with the negative regulation of germination by suboptimal temperature include up-regulation of ABA biosynthesis genes, ABA-responsive genes, as well as other genes previously related to physiological dormancy and inhibition of germination. Thus, our manuscript provides the first insights into the gene expression patterns involved in the response to suboptimal temperature during seed imbibition in a tropical palm species.

Micro/nano-hierarchical scaffold fabricated using a cell electrospinning/3D printing process for co-culturing myoblasts and HUVECs to induce myoblast alignment and differentiation

Human skeletal muscle is composed of intricate anatomical structures, including uniaxially arranged myotubes and widely distributed blood capillaries. In this regard, vascularization is an essential part of the successful development of an engineered skeletal muscle tissue to restore its function and physiological activities. In this paper, we propose a method to obtain a platform for co-culturing human umbilical vein endothelial cells (HUVECs) and C2C12 cells using cell electrospinning and 3D bioprinting. To elaborate, on the surface of mechanical supporters (polycaprolactone and collagen struts) with a topographical cue, HUVECs-laden alginate bioink was uniaxially electrospun. The electrospun HUVECs showed high cell viability (90%), homogeneous cell distribution, and efficient HUVEC growth. Furthermore, the myoblasts (C2C12 cells), which were seeded on the vascularized structure (HUVECs-laden fibers), were co-cultured to facilitate myoblast regeneration. As a result, the scaffold that included myoblasts and HUVECs represented a high degree of the myosin heavy chain (MHC) with striated patterns and enhanced myogenic-specific gene expressions (MyoD, troponin T, MHC and myogenin) as compared to the scaffold that included only myoblasts. STATEMENT OF SIGNIFICANCE: Cell electrospinning is an advanced electrospinning method that improves cell-matrix interactions by embedding cells directly into micro/nanofibers. Here, cell electrospinning was employed to achieve not only the homogeneous human umbilical vein endothelial cells (HUVECs) distribution with a high cell-viability (~90%), but also highly aligned topographical cue. Moreover, the uniaxially micropatterned PCL/collagen struts as a physical support were generated using three-dimensional (3D) printing, and was covered with HUVEC-laden micro/nanofibers. This hierarchical structure provided meaningful mechanical stability, homogeneous cell distribution, and HUVEC transformation into a narrow, elongated structure. Furthermore, the myoblasts (C2C12 cells) were seeded on the HUVECs-laden fibers and cocultured to facilitate myogenesis. In brief, a myosin heavy chain with striated patterns and enhanced myogenic specific gene expressions were represented.

Cell-Electrospinning and Its Application for Tissue Engineering

Electrospinning has gained great interest in the field of regenerative medicine, due to its fabrication of a native extracellular matrix-mimicking environment. The micro/nanofibers generated through this process provide cell-friendly surroundings which promote cellular activities. Despite these benefits of electrospinning, a process was introduced to overcome the limitations of electrospinning. Cell-electrospinning is based on the basic process of electrospinning for producing viable cells encapsulated in the micro/nanofibers. In this review, the process of cell-electrospinning and the materials used in this process will be discussed. This review will also discuss the applications of cell-electrospun structures in tissue engineering. Finally, the advantages, limitations, and future perspectives will be discussed.

Anisotropically Aligned Cell-Laden Nanofibrous Bundle Fabricated via Cell Electrospinning to Regenerate Skeletal Muscle Tissue

For muscle regeneration, a uniaxially arranged micropattern is important to mimic the structure of the natural extracellular matrix. Recently, cell electrospinning (CE) has been tested to fabricate cell-laden fibrous structures by embedding cells directly into micro/nanofibers. Although homogenous cell distribution and a reasonable cell viability of the cell-laden fibrous structure fabricated using the CE process are achieved, unique topographical cues formed by an aligned fibrous structure have not been applied. In this study, a CE process to achieve not only homogeneous cell distribution with a high cell viability, but also highly aligned cells, which are guided by aligned alginate fibers is employed. To attain the aligned cell-laden fibrous structure, various processing conditions are examined. The selected condition is applied using C2C12 myoblast cells to ensure the biocompatibility and guidance of cell elongation and alignment. As a control, a cell-printed scaffold using a 3D bioprinter is used to compare the efficiency of cell alignment and differentiation of myoblasts. Highly arranged, multinucleated cell morphology is confirmed in the CE scaffold, which successively facilitates myogenic differentiation. It is believed that this study will be a new platform for obtaining cell alignment and will significantly benefit the efforts on muscle regeneration.

Tuberculosis infection via the emergency department among inpatients in South Korea: a propensity score matched analysis of the National Inpatient Sample

BACKGROUND

Emergency departments (EDs) carry a high risk of infectious disease transmission and have also been implicated in tuberculosis (TB) outbreaks.

AIM

To determine if patients who visit EDs have an increased risk of TB infection. Using South Korean inpatient sample data (2012), the risk of TB occurrence during 90 days after hospitalization for patients admitted via EDs was compared with that for patients admitted via outpatient clinics.

METHODS

The data of the 2012 Health Insurance Review and Assessment Service - National Inpatient Sample were used. TB diagnosis was based on International Classification of Diseases Version 10 [all TB (A15-A19), pulmonary TB (A15-A16) and extrapulmonary TB (A17-A18)].

FINDINGS

After propensity score matching using the demographic and clinical characteristics of the patients, 191,997 patients (64,017 patients admitted via EDs and 127,908 patients admitted via outpatient clinics) were included in this study. There was no significant difference in baseline patient characteristics between the two groups. The percentage of patients with TB admitted via EDs was higher than that of patients admitted via outpatient clinics. The likelihood of active TB occurrence was 30% higher for all TB [hazard ratio (HR) 1.30; 95% confidence interval (CI) 1.12-1.52] and pulmonary TB (HR 1.30; 95% CI 1.10-1.53) in patients admitted via EDs compared with patients admitted via outpatient clinics; this difference was significant. However, no difference in the occurrence of extrapulmonary TB was observed between the two groups.

CONCLUSIONS

The likelihood of TB infection was greater in patients admitted via EDs than in patients admitted via outpatient clinics.

Development of a tannic acid cross-linking process for obtaining 3D porous cell-laden collagen structure

Cell-printing is an emerging technique that enables to build a customized structure using biomaterials and living cells for various biomedical applications. In many biomaterials, alginate has been widely used for rapid gelation, low cost, and relatively high processability. However, biocompatibilities enhancing cell adhesion and proliferation were limited, so that, to overcome this problem, an outstanding alternative, collagen, has been extensively investigated. Many factors remain to be proven for cell-printing applications, such as printability, physical sustainability after printing, and applicability of in vitro cell culture. This study proposes a cell-laden collagen scaffold fabricated via cell-printing and tannic acid (TA) crosslinking process. The effects of the crosslinking agent (0-3wt% TA) in the cell-laden collagen scaffolds on physical properties and cellular activities using preosteoblasts (MC3T3-E1) were presented. Compared to the cell-laden collagen scaffold without TA crosslinking, the scaffold with TA crosslinking was significantly enhanced in mechanical properties, while reasonable cellular activities were observed. Concisely, this study introduces the possibility of a cell-printing process using collagen and TA crosslinking and in vitro cell culture for tissue regeneration.

Preparation and characterization of gelatin/α-TCP/SF biocomposite scaffold for bone tissue regeneration

In this study, we suggest a new biocomposite scaffold composed of gelatin/α-TCP (tricalcium phosphate)/SF (silk-fibroin) (GTS) which has enhanced mechanical strength and high level of cellular activity. To fabricate GTS scaffold, a temperature-controlled 3D printing process was used and appropriate printing conditions were selected based on rheological data. To show the feasibility as a biomedical scaffold for bone tissue regeneration, the various physical and biological results, using MG63 (osteoblast-like cells), of the GTS scaffold were compared with those of a pure gelatin (G) and gelatin/α-TCP (GT) composite scaffold. GTS scaffolds showed enhanced mechanical properties in dry and wet state compared to those of the G and GT scaffolds. Also, significantly high cell-proliferation and differentiation of MG63 cells were observed in the GTS scaffold. Therefore, the GTS composite scaffold will be one of highly potential biomaterials to be used in bone regeneration.

Recent cell printing systems for tissue engineering

Three-dimensional (3D) printing in tissue engineering has been studied for the bio mimicry of the structures of human tissues and organs. Now, it is being applied to 3D cell printing, which can position cells and biomaterials, such as growth factors, at desired positions in the 3D space. However, there are some challenges of 3D cell printing, such as cell damage during the printing process and the inability to produce a porous 3D shape owing to the embedding of cells in the hydrogel-based printing ink, which should be biocompatible, biodegradable, and non-toxic, etc. Therefore, researchers have been studying ways to balance or enhance the post-print cell viability and the print-ability of 3D cell printing technologies by accommodating several mechanical, electrical, and chemical based systems. In this mini-review, several common 3D cell printing methods and their modified applications are introduced for overcoming deficiencies of the cell printing process.

Delivery of rural and remote health care via a broadband Internet Protocol network – views of potential users

summary

We asked the views of potential users of a proposed Canadian broadband Internet Protocol (IP) network for health, the Alberta SuperNet. The three user groups were drawn from the public, provider and private sectors. In all, 35 health-sector participants were selected (17 government, nine health-care organizations, five providers/ practitioners and four private sector). The questionnaire was Web-based, semistructured and self-administered. It consisted of four major areas: value, readiness, effect on usual care and limitations. A total of 28 (80%) individuals responded to the questionnaire: 21 (81%) were from the public sector (three provincial, nine regional and nine organizational), three (60%) were from the provider sector and four (100%) were from the private sector. Overall, the items related to health services and health human resources were considered to be the most valuable to rural communities. Respondents identified the expansion of telehealth services as the most important, except those from the private sector, who ranked this a close second. The health system's move to the use of electronic health records was ranked second in importance by all respondents. The private-sector respondents viewed all user groups to be generally less ready (mean score 2.5 on a seven-point scale from 1 = not ready to 7 = ready), while the public-sector respondents were the most optimistic (mean score 4.0). Specific socioeconomic impact data were limited. The top-ranked disadvantage of the 10 suggested was that ‘Changes in health-service delivery practices and/or processes will be required’.

Combining a micro/nano-hierarchical scaffold with cell-printing of myoblasts induces cell alignment and differentiation favorable to skeletal muscle tissue regeneration

Biomedical scaffolds must be used in tissue engineering to provide physical stability and topological/biochemical properties that directly affect tissue regeneration. In this study, a new cell-laden scaffold was developed that supplies micro/nano-topological cues and promotes efficient release of cells. The hierarchical structure consisted of poly(ε-caprolactone) macrosized struts for sustaining a three-dimensional structural shape, aligned nanofibers obtained with optimized electrospinning, and cell-printed myoblasts. Importantly, the printed myoblasts were fully safe and were efficiently released from the cell-laden struts to neighboring nanofiber networks. The incorporation of micro/nanofibers in the hierarchical scaffold significantly affected myoblast proliferation, alignment, and even facilitated the formation of myotubes. We observed that myosin heavy chain expression and the expression levels of various myogenic genes (MyoD, myogenin, and troponin T) were significantly affected by the fiber alignment achieved in our hierarchical cell-laden structure. We believe that the combination of cell-printing and a hierarchical scaffold that encourages fiber alignment is a highly promising technique for skeletal muscle tissue engineering.

Community-based sampling methods for surveillance of the Chagas disease vector, Triatoma dimidiata (Hemiptera: Reduviidae: Triatominae)

In Guatemala, the most widespread vector of Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae), the causative agent of Chagas disease, is Triatoma dimidiata (Latreille) (Hemiptera: Reduviidae: Triatominae). T. dimidiata is native to Guatemala and is present in both domestic and sylvatic habitats. Consequently, control of T. dimidiata is difficult because after successful elimination from homes, individual insects can recolonize homes from the surrounding environment. Therefore, intensive long-term surveillance of this species is essential to ensure adequate control is achieved. Manual inspection for signs of infestation, the current method used to monitor Triatominae throughout Central and South America, is labor and time-consuming, so cost-effective alternatives are needed. The current study compared the effectiveness of the current method of surveillance of T. dimidiata with community-based techniques of G6mez-Nuñez sensor boxes, collection and observation of bugs by householders, and presence of triatomine-like feces on walls. Although manual inspection was the most sensitive method when used alone, collection by householders also was sensitive and specific and involved less effort. Sensor boxes were not sensitive indicators of T. dimidiata infestation when used alone. Two recorded variables, visual inspection for feces and the sighting of bugs by householders, were sensitive and specific indicators of infestation, and in combination with collection by householders and sensor boxes these methods were significantly more likely to detect infestations than manual inspection alone. A surveillance program that combines multiple community-based techniques should have low cost and involve minimal effort from the government and at the same time promote sustainable community involvement in disease prevention.

Risk factors for domestic infestation by the Chagas disease vector, Triatoma dimidiata in Chiquimula, Guatemala

In Guatemala prior to control initiatives, the main vectors of Trypanosoma cruzi, the causative agent of Chagas disease, were Rhodnius prolixus and Triatoma dimidiata. This study conducted in 2006 in the department of Chiquimula recorded a high level of T. dimidiata infestation and an absence of R. prolixus in all surveyed communities. In Guatemala, the presence of T. dimidiata as domestic, peridomestic and sylvatic populations results in control difficulties as houses are re-infested from the surrounding environment. Entomological surveys, the current method used to select houses in need of control efforts, are labour intensive and time consuming. A time- and cost-effective way to prioritize houses for evaluation and subsequent treatment is the stratification of houses based on the risk of triatomine infestation. In the present study, 17 anthropogenic risk factors were evaluated for associations with house infestation of T. dimidiata including: wall, floor and roof type. There was an increased likelihood of domestic infestation with T. dimidiata associated with the presence of dirt floors (18/29; OR 8.075, 95% CI 2.13-30.6), uncoated bajareque walls (12/17; OR 4.80, 95% CI 1.35-17.1) and triatomine-like faeces on walls (16/26; OR 3.89, 95% CI 1.19-12.7). These factors could be used to target control of T. dimidiata to communities with an increased risk of being infested.

A reappraisal of functional reconstruction of extension of the knee following quadriceps resection or loss

The current indications for functional restoration of extension of the knee following quadriceps resection or loss require reappraisal. The contribution of pedicled and free functional muscle transfer is likely to be over-emphasised in many studies, with good functional outcomes predominantly reported only in the context of cases with residual quadriceps function. In cases with total quadriceps resection or loss, all forms of reconstruction perform poorly. Furthermore, in smaller resections with loss of two or fewer components of the quadriceps, minimal impairment of function occurs in the absence of functional reconstruction, suggesting that functional restoration may not be warranted. Thus there is a paradox in the current approach to quadriceps reconstruction, in that small resections are likely to be over-treated and large resections remain under-treated. This review suggests a shift is required in the approach and rationale for reconstructing functional extension of the knee after quadriceps resection or loss. A classification based on current evidence is suggested that emphasises more clearly the indications and rationale for functional transfers.

Factors predicting deviation from an enhanced recovery programme and delayed discharge after laparoscopic colorectal surgery

AIM

The study aimed to identify factors that predict postoperative deviation from an enhanced recovery programme (ERP) and/or delayed discharge following colorectal surgery.

METHOD

Data were prospectively collected from all patients undergoing elective laparoscopic colorectal resection between January 2006 and December 2009. They included Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (POSSUM) variables, body mass index (BMI), sex, preoperative serum albumin, pathology, conversion from a laparoscopic to an open approach and postoperative length of hospital stay.

RESULTS

There were 176 patients (90 women) of mean age 68 years. Fifteen (9%) operations were converted from laparoscopic to open. The remainder were completed laparoscopically. Fifty-five (31%) deviated from the ERP, with most failing multiple elements. The most common reason was failure to mobilize, which often occurred in conjunction with paralytic ileus or analgesic failure. Factors independently predicting ERP deviation on multivariate analysis were pathology and intra-operative complications. The median length of stay was 5 days. Sixty-four (36%) patients had a prolonged length of stay that was predicted by age, number of procedures and ERP deviation.

CONCLUSION

Pathology and intra-operative complications are independent predictors of ERP deviation. Prolonged length of stay can be predicted by age, multiple procedures and ERP deviation. Failure to mobilize should be considered as a red flag sign prompting further investigation following colorectal resection.

Plasma ghrelin levels and their relationship with gastric emptying in patients with dysmotility-like functional dyspepsia

BACKGROUND/AIMS

Ghrelin affects gastric motility. However, little is known about the role of ghrelin in the pathophysiology of functional dyspepsia (FD). We investigated plasma ghrelin levels and their relationship with gastric emptying time in dysmotility-like FD patients.

METHODS

42 patients with dysmotility-like FD and 14 healthy volunteers were enrolled in the study. Gastric half-emptying time was measured using a radiolabeled meal. Plasma total ghrelin levels before and after the meal were determined using a radioimmunoassay kit.

RESULTS

Preprandial ghrelin levels were significantly lower in FD patients than in controls. Postprandial ghrelin levels were similar between the two groups. Abnormally low preprandial ghrelin levels were observed in 7 out of 42 patients, in whom significant postprandial decrease of ghrelin levels was absent. Delayed gastric emptying was observed in 5 out of 7 patients with abnormally low ghrelin levels. Pre- or postprandial ghrelin levels were not significantly correlated with gastric half-emptying time, both in the patient group and in the control group.

CONCLUSIONS

Abnormally low preprandial ghrelin levels and absence of significant postprandial decrease of ghrelin levels are present in a subset of dysmotility-like FD patients. Further investigation on the pathogenetic implication of these alterations in FD is required.

Novel action of gastric proton pump inhibitor on suppression of Helicobacter pylori induced angiogenesis

BACKGROUND

Although activation of mitogen activated protein kinases (MAPKs) by Helicobacter pylori infection is associated with induction of host angiogenesis, which may contribute to H pylori associated gastric carcinogenesis, the strategy for its prevention has not been identified. As we previously reported a strong inhibitory action of gastric proton pump inhibitors (PPIs) on MAPK extracellular signal regulated kinase (ERK)1/2 phosphorylation, we investigated whether PPIs could suppress the H pylori induced angiogenesis via inhibition of MAPK ERK1/2.

METHODS

To address the relationship between H pylori infection and angiogenesis, comparative analysis of density of CD34(+) blood vessel was performed in tissues obtained from 20 H pylori positive gastritis and 18 H pylori negative gastritis patients. Expression of hypoxia inducible factor 1 (HIF-1alpha) and vascular endothelial growth factor (VEGF) was tested by reverse transcription-polymerase chain reaction and secretion of interleukin 8, and VEGF was measured by ELISA. To evaluate the direct effect of H pylori infection on the tubular formation of human umbilical vein endothelial cells (HUVEC), an in vitro angiogenesis assay was employed. Activation of MAPK and nuclear factor kappaB (NFkappaB) was detected by immunoblotting.

RESULTS

H pylori positive gastritis patients showed a higher density of CD34(+) blood vessels (mean 40.9 (SEM 4.4)) than H pylori negative gastritis patients (7.2+/-0.8), which was well correlated with expression of HIF-1alpha. Conditioned media from H pylori infected gastric epithelial cells directly induced tubular formation of HUVEC and the increase of in vitro angiogenesis was suppressed by PPI treatment. Infection of H pylori significantly upregulated expression of HIF-1alpha and VEGF in gastric epithelial cells and expression of proangiogenic factors was mediated by MAPK activation and partially responsible for NFkappaB activation. PPIs effectively inhibited the phosphorylation of MAPK ERK1/2 that is a principal signal for H pylori induced angiogenesis.

CONCLUSIONS

The fact that PPIs could downregulate H pylori induced angiogenesis indicates that antiangiogenic treatment using a PPI could be a promising protective therapeutic approach for H pylori associated carcinogenesis.

Incorporating ethics in priority setting: a case study of a regional health board in Canada

The authors were involved in developing an ethical framework to assist the Queens Region Board (Prince Edward Island, Canada) set priorities in health and health care. Two and one half years after the adoption of this framework, the authors undertook an evaluation of the framework. This paper will discuss: (a) the historical background of regionalization in Canada, and in particular the circumstances leading up to the institution of regional boards in Prince Edward Island; (b) the sorts of ethical issues facing the Queens Regional Board; (c) issues arising in connection with the use and development of ethics frameworks for managing ethical issues in priority setting; (d) the framework adopted by the Queens Board and the process that led to its development; (e) issues arising as concerns implementation of the framework; (f) questions and issues pertinent to other boards and bodies considering similar initiatives.

Different role of functional domains of hTR in DNA binding to telomere and telomerase reconstruction

Even if template sequence of hTR played an essential role in telomere binding, a 326 nucleotide fragment of hTR containing template, pseudoknot, and CR4-5 domains is critical for both binding with telomeric DNA and reconstitution of telomerase activity. A functional study with antisense oligonucleotides suggested that targeted disruption of the template region efficiently abrogated both telomeric DNA binding and telomerase activity, whereas disruption of the CR4-5 region induced only loss of telomerase activity. hTR interacts with telomeric DNA via structural region composed of the template, pseudoknot, and CR4-5 domains, however, each structural domain plays a distinct role in telomere binding and telomerase activity reconstitution.

Acute opioid withdrawal on accidental injection of naltrexone

We report two 16-year-old female intravenous drug users who, after making purchases from street suppliers, both presented with symptoms of acute opioid withdrawal. Urine toxicology revealed naltrexone, a long-acting opioid antagonist used in detoxification and maintenance therapy in opioid dependence. While the safety and efficacy of opiate antagonist treatment is being debated, the present case highlights the vulnerability of this young population. The recent availability of non-prescribed opiate antagonists suggests that both health professionals and young people themselves need to be aware of their effects.

Adolescent admissions to a tertiary paediatric hospital: a dynamic pattern

INTRODUCTION

Adolescent inpatient facilities emerged in Australia in the 1980s to cater for an increasing number of young people with chronic illness and disability. Yet, there is minimal published data on the number of young people admitted to hospital within these units, their unit of admission, length of stay or reason for admission. A 12-year audit of adolescents admitted to a tertiary hospital with a dedicated adolescent unit and adolescent medicine programme in Victoria, Australia, was conducted to review the pattern of hospitalisation in young people in order to provide data to assist healthcare policy and planning agendas.

MATERIALS AND METHODS

Admissions to the Royal Children's Hospital in Victoria, Australia, of adolescents aged 10 years and above were reviewed over a 12-year period from 1990 to 2001. We identified the annual number of adolescents admitted, the proportion of adolescents admitted to the Adolescent Inpatient Unit (ward) and annual admissions under the Adolescent Medicine Unit (department).

RESULTS

Adolescents now constitute nearly 30% of all admissions at this children's hospital. Over this period, admissions to the Adolescent Inpatient Unit have nearly doubled and annual admissions under the Adolescent Medicine Unit rose from 38 to 288. The majority of adolescents were admitted under specialty medical and surgical units.

CONCLUSIONS

The knowledge that nearly one in three admissions to this tertiary children's hospital is over 10 years old should help promote the development of planning and policy agendas that better balance both health and developmental priorities in this age group.

Strategies to promote better outcomes in young people with chronic illnesses

INTRODUCTION

This paper aims to provide an overview of chronic illness and disability in young people, focusing on the developmental needs of young people and the impact of chronic illness on adolescence. The emotional well-being of the young person with chronic illness is explored and strategies that promote better health outcomes for the young person through health, family and school settings are discussed.

METHODS

Literature was searched using Medline from 1980 to 2002 using the keywords chronic illness, chronic disease, disability, psychological, social, outcomes and transition. Articles were also hand searched from retrieved articles.

CONCLUSIONS

Young people with chronic illness have the same developmental needs as other adolescents. Traditional health care is focused on disease outcomes; however, young people do not necessarily share the same focus. Improving health outcomes for young people involves health professionals having an understanding of adolescent development and broadening the medical perspective to incorporate the developmental perspective. Building competence in young people with chronic illness, strengthening connectedness within the family, school and peer group and building the capacity of the health care team in different settings will provide opportunities to enhance resilience in young people with chronic illness. In doing so, their health outcomes will hopefully also be improved.

Membrane blebbing during apoptosis results from caspase-mediated activation of ROCK I

The execution phase of apoptosis is characterized by marked changes in cell morphology that include contraction and membrane blebbing. The actin-myosin system has been proposed to be the source of contractile force that drives bleb formation, although the biochemical pathway that promotes actin-myosin contractility during apoptosis has not been identified. Here we show that the Rho effector protein ROCK I, which contributes to phosphorylation of myosin light-chains, myosin ATPase activity and coupling of actin-myosin filaments to the plasma membrane, is cleaved during apoptosis to generate a truncated active form. The activity of ROCK proteins is both necessary and sufficient for formation of membrane blebs and for re-localization of fragmented DNA into blebs and apoptotic bodies.

Alternative splicing of the neurotrophin-3 gene gives rise to different transcripts in a number of human and rat tissues

The mouse neurotrophin-3 (NT-3) gene has been shown to contain two exons (exon 1A and exon 1B) upstream of the single coding exon (exon 2). These upstream exons are alternatively spliced to the coding exon, generating two different NT-3 transcripts. We investigated whether alternative splicing of two upstream exons also occurs in the human and rat NT-3 gene. It was found that the human and rat NT-3 gene also contains two exons upstream of the main coding exon and that alternative splicing of these upstream exons generates two different NT-3 transcripts : transcript 1A and transcript 1B (TR1B). These two transcripts were widely expressed in several human and rat tissues. Also, a third transcript, transcript 1A1C, derived from splicing of exon 1A to exon 1B before splicing to the coding exon was seen in a small number of rat tissues. Previous quantification of neurotrophin-3 mRNA has not been transcript-specific. Here we describe a transcript-specific semiquantitative RT-PCR method allowing the quantification of TR1B in human tissues. We show that this is the major NT-3 transcript and that expression of this transcript was much higher in the adult when compared with the corresponding fetal tissues.

Role of caspase-3 in apoptosis of colon cancer cells induced by nonsteroidal anti-inflammatory drugs

Epidemiological studies have demonstrated that nonsteroidal anti-inflammatory drugs (NSAIDs) decrease the incidence of and mortality from colon cancer. In addition, NSAIDs reduce the number and the size of polyps in patients with familial adenomatous polyposis. The mechanisms responsible for the antineoplastic effect of NSAIDs are not yet completely understood, but one of the possible mechanisms is an induction of apoptosis. We explored the role of caspase-3, a major apoptosis-executing enzyme, in NSAID-induced apoptosis of colon cancer cell line HT-29. Treatment of HT-29 cells with indomethacin induced a dramatic increase in caspase-3-like protease activity measured by a cleavage of the fluorogenic substrate Ac-DEVD-AMC. Western blot analysis showed that indomethacin treatment led both to decrease in procaspase-3 and to cleavage of its substrate poly(ADP-ribose) polymerase (PARP). Furthermore, the caspase-3-like protease inhibitor Ac-DEVD-CHO attenuated indomethacin-induced DNA fragmentation dose dependently. However, mRNA expression of CASP genes was not affected by the addition of indomethacin, highlighting the importance of posttranslational modification of this enzyme for the activation. These results suggest that NSAIDs, including indomethacin, induce apoptosis in colon cancer cells through a caspase-3 dependent mechanism which may contribute to the chemopreventive functions of these agents.

Staphylococcus lugdunensis: report of first case of skin and soft tissue infection in Singapore

We report the first case of skin and soft tissue infection due to Staphylococcus lugdunensis in Singapore. This is a coagulase negative Staphylococcus species known to cause a wide variety of more serious infections--brain abscess, sepsis, chronic osteomyelitis and infective endocarditis.

Autologous transfusion in obstetrics

AIM OF STUDY

To assess the safety of blood collection for autologous transfusion in pregnant women and the effects of the procedure on the fetus.

METHOD

Prospective study involving obstetric patients undergoing elective lower segment Caesarean section (LSCS) between 1993 and 1994 were recruited for autologous transfusion. Continuous cardiotocograph monitoring was carried out throughout the duration of the procedure and the fetal haemodynamics was studied before and after by doppler blood flow ultrasound.

RESULTS

The results show that there was no fetal deceleration or increased uterine activity as monitored by cardiotocography. The mean pulsatility index (PI) for the umbilical artery before the procedure was 0.9560 and after was 0.0820 which is a significant difference (p value = 0.035).

CONCLUSION

Autologous blood collection seems to be a safe procedure for both the mother and the fetus. However, autologous transfusion remains an unpopular choice amongst pregnant women.

Epidemiological surveillance of melioidosis in Singapore

During the period 1989 to 1996, a total of 372 cases of melioidosis, with 147 deaths, were reported, giving a mean annual incidence rate of 1.7 per 100,000 population and a case-fatality rate of 39.5%. Majority (89%) of the clinical cases were confirmed by culture of Burkholderia pseudomallei, while the others were presumptive cases based on a single blood specimen with an indirect haemaglutination (IHA) antibody titre of > or = 1:16. The highest incidence rate was reported in those aged 45 years and above (5.7 per 100,000 population), males (2.8 per 100,000 population), and Indian ethnic group (3.0 per 100,000 population). Cases were distributed throughout the island all year round. There was no correlation with rainfall. Most of the cases (77.4%) had other concurrent medical conditions, the most common being diabetes mellitus (57.5%). Factors significantly associated with a higher case-fatality rate were age (55 years and above), septicaemia, smoking history and heart or renal failure. The overall case-fatality rate has been declining from 60% in 1989 to 27% in 1996 due to a greater awareness among medical practitioners to diagnose and treat the disease early. The overall seroprevalence of IHA antibody (titre of > or = 1:16) among asymptomatic population groups was 0.2%. B. pseudomallei isolated from clinical specimens were sensitive to imipenem (100%), ceftazidime (99.1%), piperacillin (99.7%), ampicillin-clavulanate (98.5%), minocycline (97.4%), chloramphenicol (94.3%), doxycycline (94.3%) and tetracycline (93.9%). Of 395 samples of soil collected during epidemiological investigation of reported cases, 1.8% were positive for B. pseudomallei.

Ecthyma gangrenosum in a patient with hypogammaglobulinemia

Ecthyma gangrenosum is a characteristic skin lesion that is caused by Pseudomonas aeruginosa (P. aeruginosa) in the majority of cases. Systemic P. aeruginosa usually complicates debilitating conditions like leukaemia, burns and cystic fibrosis. We report a patient with underlying hypogammaglobulinemia who developed ecthyma gangrenosum secondary to P. aeruginosa septicaemia, which was potentially life-threatening. Recognition of the characteristic skin lesions with prompt initiation of appropriate antibiotics and intravenous immunoglobulins were life-saving. A review of the English literature reports three other cases of ecthyma gangrenosum in patients with underlying hypogammaglobulinemia.