Effect of Injectable Acellular Adipose Matrix on Soft Tissue Reconstruction in a Murine Model

BACKGROUND

The extracellular matrix isolated from adipose tissue, known as acellular adipose matrix (AAM), represents a novel biomaterial. AAM functions as a scaffold that not only supports stem cell proliferation and differentiation but also induces adipogenesis and angiogenesis. This study aims to investigate the volumetric effects and microenvironmental changes associated with injectable AAM in comparison to conventional fat grafting.

METHODS

AAM was manufactured from fresh human abdominoplasty fat using a mechanically modified method and then transformed into an injectable form. Lipoaspirate was harvested employing the Coleman technique. A weight and volume study was conducted on athymic nude mice by injecting either injectable AAM or lipoaspirate into the scalp (n=6 per group). After eight weeks, graft retention was assessed through weight measurement and volumetric analysis using micro-computed tomography (micro-CT) scanning. Histological analysis was performed using immunofluorescence staining for perilipin and CD31.

RESULTS

Injectable AAM exhibited similar weight and volume effects in murine models. Histological analysis revealed comparable inflammatory cell presence with minimal capsule formation when compared to conventional fat grafts. Adipogenesis occurred in both AAM-injected and conventional fat graft models, with no significant difference in the blood vessel area (%) between the two.

CONCLUSIONS

In summary, injectable AAM demonstrates effectiveness comparable to conventional fat grafting concerning volume effects and tissue regeneration in soft tissue reconstruction. This promising allogeneic injectable holds the potential to serve as a safe and effective "Off-the-Shelf" alternative in both aesthetic and reconstructive clinical practices.

NO LEVEL ASSIGNED

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Facility patient volume and survival among individuals diagnosed with malignant central nervous system tumors

PURPOSE

Prior research indicates that the volume of central nervous system (CNS) tumor patients seen by a facility is associated with outcomes. However, most studies have focused on short-term survival and specific CNS tumor subtypes. Our objective was to examine whether facility CNS tumor patient volume is associated with longer-term CNS tumor survival overall and by subtype.

METHODS

We obtained National Cancer Database (NCDB) data including individuals diagnosed with CNS tumors from 2004 to 2016. Analyses were stratified by age group (0-14, 15-39, 40-64, and ≥ 65 years) and tumor type. We used Cox Proportional Hazards (PH) regression and restricted mean survival time (RMST) analyses to examine associations between survival and facility patient volume percentile category adjusting for potential confounding factors.

RESULTS

Our analytic dataset included data from 130,830 individuals diagnosed with malignant first primary CNS tumors. We found a consistently reduced hazard rate of death across age groups for individuals reported by higher vs. lower (> 95th vs. ≤ 70th percentile) volume facilities (hazard ratio (HR)_0-14 = 0.78, 95% confidence interval (CI) 0.64-0.95; HR_15-39 = 0.87, 95% CI 0.78-0.96; HR_40-64 = 0.82, 95% CI 0.76-0.88; HR_≥65 = 0.80, 95% CI 0.75-0.86). Significantly longer survival times within 5 years for higher vs. lower volume facilities were observed ranging from 1.20 months (15-39) to 3.08 months (40-64) higher. Associations varied by CNS tumor subtype for all age groups.

CONCLUSIONS

These results suggest facility factors influence CNS tumor survival with longer survival for patients reported by higher volume facilities. Understanding these factors will be critical to developing strategies that eliminate modifiable differences in survival times.

Effect of long-term confinement on metabolic and physiological parameters in mice

Long-term and mild confinement or isolation in an enclosed environment can occur in situations such as disasters, specific political, economic or social events, nuclear shelters, seabed exploration, polar expeditions, and space travel. To investigate the effects of stress caused by long-term confinement in an enclosed environment in mammals, we divided 8-week-old C57BL/6J mice into four groups that were housed in a closed environment with a narrow metabolic cage (stress group), normal metabolic cage (control group), conventional cage (conventional group) or conventional cage with wire mesh floor (wire mesh group). The phenotypes of the mice were examined for four weeks, followed by behavioral tests. Weight gain suppression was observed in the stress group. Continuous analysis of these mice every two minutes for four weeks using an implanted measuring device showed a significantly decreased amount of spontaneous activity and subcutaneous temperature in the stress group. After housing in each environment for four weeks, the behavioral tests of mice in the stress group also revealed a shorter latency to fall off in the rotarod test and shorter stride length and interstep distance in the footprint test. Interestingly, the lower spontaneous activity of mice in the stress group was rescued by housing in conventional cages. These results suggest a temporary effect of long-term confinement in an enclosed environment as a chronic and mild stress on homeostasis in mammals.

[Statement of the surgical working group for liver, gall bladder and pancreatic diseases (CALGP) of the German Society for General and Visceral Surgery (DGAV) on rapid report V19-03: association between volume of cases and quality in complex pancreatic surgery]

The Institute for Quality and Efficiency in Health Care (IQWiG) was commissioned by the Federal Joint Committee (G‑BA) to carry out a systematic literature search and assessment of the evidence for the association between the hospital and surgeon volume of cases and the quality of the treatment results in complex pancreatic surgery. The results are presented in the rapid report V19-03. The report confirms an association between the number of cases and the quality of the treatment results in favor of hospitals and surgeons with high volume case numbers; however, a statement with respect to the minimum numbers of complex pancreatic interventions is not given. The surgical working group for liver, gall bladder and pancreatic diseases (CALGP) of the German Society for General and Visceral Surgery (DGAV) comments on these conclusions.

Very Strong but Reversible Immobilization of Enzymes on Supports Coated with Ionic Polymers

In this chapter, the properties of tailor-made anionic exchanger resins based on films of large polyethylenimine polymers (e.g., molecular weight 25,000) as supports for strong but reversible immobilization of proteins are shown. The polymer is completely coated, via covalent immobilization, the surface of different porous supports. Proteins can interact with this polymeric bed, involving a large percentage of the protein surface in the adsorption. Different enzymes have been very strongly adsorbed on these supports, retaining enzyme activities. On the other hand, adsorption is very strong and the derivatives may be used under a wide range of pH and ionic strengths. These supports may be useful even to stabilize multimeric enzymes, by involving several enzyme subunits in the immobilization.

Evolution of acoustic softening effect on ultrasonic-assisted micro/meso-compression behavior and microstructure

The application of ultrasonic vibration is an effective method to overcome the processing problems in micro/meso-forming. Previously it was observed that ultrasonic vibration could reduce flowing stress in the forming process, called ultrasonic volume effect. The volume effect contains multi-mechanisms such as stress superposition leading to apparent average stress reduction, acoustic softening and ultrasonic impact leading to real stress reductin. However, the evolutional characteristics and the mechanism of acoustic softening on material deformation is still not clear. And in most previous studies only the average stress but not the oscillatory stress was measured due to the convenience of dynamic force sensing system, which confused the different ultrasonic volume effects, acoustic softening, stress superposition and ultrasonic impact. The purpose of this study is to investigate the effects of acoustic softening on micro/meso-compression behavior and microstructure evolution. An ultrasonic-assisted compression test system with dynamic force sensing technology was developed. And a series of ultrasonic-assisted micro/meso-compression tests at different amplitudes were carried out on pure copper C1100O combining the microstructure analysis by EBSD technique. By analyzing the waveform of the oscillatory stress in the process, acoustic softening was successfully separated from the stress superposition and it was found that the deformation strain plays an important role on the effect of acoustic softening. The stress reduction by acoustic softening increases with the flowing strain or ultrasonic amplitude increasing. Besides, there is an evolutionary transition of acoustic softening ratio between small strain and large strain. When acoustic softening occurs, the low-angle grain boundaries distribute randomly in grains, compared to the piled distribution without ultrasonic assistance, implying motions of the low-angle grain boundaries or dislocation is improved by acoustic softening, resulting in the real stress reduction. In addition, with small deformation strain, the elongated grain becomes equiaxed and dislocation density is significantly reduced, which may be the result of the increased dislocation annihilation due to ultrasonic-induced dynamic recovery. However, with the deformation strain increasing to some extent, acoustic hardening gradually becomes significant, leading to much less effectiveness of acoustic softening on dislocation density reduction. The findings of this study provide an instructive understanding of the underlying mechanisms of acoustic softening in ultrasonic-assisted micro/meso-forming.

Investigation on ultrasonic volume effects: Stress superposition, acoustic softening and dynamic impact

Conventional high power ultrasonic vibration has been widely used to improve manufacturing processes like surface treatment and metal forming. Ultrasonic vibration affects material properties, leading to a flow stress reduction, which is called ultrasonic volume effect. The volume effect contains multi-mechanisms such as stress superposition due to oscillatory stress, acoustic softening by easier dislocation motion and dynamic impact leading to extra surface plastic deformation. However, most researches ignored the stress superposition for the convenience of measurement, and few studies considered ultrasonic dynamic impact since the relatively low ultrasonic energy in macro scale. The purpose of this study is to investigate the characteristics and mechanisms of different ultrasonic volume effects in micro-forming. A 60 kHz longitudinal ultrasonic-assisted compression test system was developed and a series of ultrasonic-assisted compression tests at different amplitudes on commercially pure aluminum A1100 in micro-scale were carried out combining the surface analysis by SEM, EDX and micro-hardness test. Three different ultrasonic volume effects, stress superposition, acoustic softening and dynamic impact, were confirmed in the ultrasonic-assisted compression tests. In order to quantitatively predict stress superposition, a hybrid model for stress superposition is developed considering the elastic deformation of experimental apparatus in practice, the evolution of the modeling results fitted well with the experimental results. With low ultrasonic amplitude, stress superposition and acoustic softening occurred because vibrated punch contacted with the specimen all the time during compression. However, with higher amplitude, due to the extra surface plastic deformation by larger ultrasonic energy, forming stress was further reduced by the ultrasonic dynamic impact. A possible method to distinguish the effects of dynamic impact and acoustic softening is to analyze the waveform of the oscillatory stress in the process. In the case of ultrasonic dynamic impact effect, a higher amount of oxidation was observed on the specimen surface, which could be the result of local heating by surface plastic deformation and surface friction when the vibrated punch detached from the specimen. The findings of this study provide an instructive understanding of the underlying mechanisms of volume effects in ultrasonic-assisted micro-forming.

Radiobiology of tissue reactions

Tissue effects of radiation exposure are observed in virtually all normal tissues, with interactions when several organs are involved. Early reactions occur in turnover tissues, where proliferative impairment results in hypoplasia; late reactions, based on combined parenchymal, vascular, and connective tissue changes, result in loss of function within the exposed volume; consequential late effects develop through interactions between early and late effects in the same organ; and very late effects are dominated by vascular sequelae. Invariably, involvement of the immune system is observed. Importantly, latent times of late effects are inversely dependent on the biologically equieffective dose. Each tissue component and--importantly--each individual symptom/endpoint displays a specific dose-effect relationship. Equieffective doses are modulated by exposure conditions: in particular, dose-rate reduction--down to chronic levels--and dose fractionation impact on late responding tissues, while overall exposure time predominantly affects early (and consequential late) reactions. Consequences of partial organ exposure are related to tissue architecture. In 'tubular' organs (gastrointestinal tract, but also vasculature), punctual exposure affects function in downstream compartments. In 'parallel' organs, such as liver or lungs, only exposure of a significant (organ-dependent) fraction of the total volume results in clinical consequences. Forthcoming studies must address biomarkers of the individual risk for tissue reactions, and strategies to prevent/mitigate tissue effects after exposure.