Physical stimuli play critical roles in the development, regeneration, and pathology of many mesenchymal tissues, most notably bone. While mature bone cells, such as osteoblasts and osteocytes, are ...clearly involved in these processes, the role of their progenitors in mechanically mediated tissue responses is unknown. In this study, we investigated the effect of cyclic substrate deformation on the proliferation and osteogenic differentiation of human mesenchymal stem cells (hMSCs). Application of equibiaxial cyclic strain (3%, 0.25
Hz) to hMSCs cultured in osteogenic media inhibited proliferation and stimulated a 2.3-fold increase in matrix mineralization over unstrained cells. The strain stimulus activated the extracellular signal-regulated kinase (ERK1/2) and p38 mitogen-activated protein kinase pathways, but had no effect on c-Jun
N-terminal kinase phosphorylation or activity. Strain-induced mineralization was largely mediated by ERK1/2 signaling, as inhibition of ERK1/2 attenuated calcium deposition by 55%. Inhibition of the p38 pathway resulted in a more mature osteogenic phenotype, suggesting an inhibitory role for p38 signaling in the modulation of strain-induced osteogenic differentiation. These results demonstrate that mechanical signals regulate hMSC function, suggesting a critical role for physical stimulation of this specific cell population in mesenchymal tissue formation.
Minimally invasive surgical procedures are increasingly important in medicine, but biomaterials consistent with this delivery approach that allow one to control the structure of the material after ...implantation are lacking. Biomaterials with shape-memorizing properties could permit minimally invasive delivery of cell transplantation constructs and enable the formation of new tissues or structures in vivo in desired shapes and sizes.
Macroporous alginate hydrogel scaffolds were prepared in a number of predefined geometries, compressed into significantly smaller, different "temporary" forms, and introduced into immunocompromised mice by means of minimally invasive surgical delivery through a small catheter. Scaffolds were rehydrated in situ with a suspension of cells (primary bovine articular chondrocytes) or cell-free medium and delivered through the same catheter. Specimens were harvested at 1 hr to evaluate the efficacy of cell delivery and the recovery of scaffold geometry, and at 8 and 24 weeks to evaluate neotissue formation.
A high percentage (88%) of scaffolds that were introduced with a catheter and rehydrated with cells had recovered their original shape and size within 1 hr. This delivery procedure resulted in cartilage structures with the geometry of the original scaffold by 2 months and histologically mature appearing tissue at 6 months.
Shaped hydrogels, formed by covalently cross-linking, can be structurally collapsed into smaller, temporary shapes that permit their minimally invasive delivery in vivo. The rapid recovery of scaffold properties facilitates efficient cell seeding in vivo and permits neotissue formation in desired geometries.
Ectopic calcification of vascular tissue is associated with several cardiovascular pathologies and likely involves active regulation by vascular smooth muscle cells and osteoblast-like vascular ...cells. This process often occurs in sites with altered mechanical environments, suggesting a role for mechanical stimuli in calcification. In this study, we investigated the effect of mechanical stimulation on the proliferation, osteogenic differentiation, calcification, and mitogen-activated protein kinase (MAPK) signaling in calcifying vascular cells (CVCs), a subpopulation of aortic smooth muscle cells putatively involved in vascular calcification. Application of equibiaxial cyclic strain (7%, 0.25
Hz) to CVCs had no effect on cell proliferation, but accelerated alkaline phosphatase expression and significantly increased mineralization by 3.1-fold over unstrained cells. Fluid motion in the absence of strain also enhanced mineralization, but to a lesser degree. Because MAPK pathways mediate mechanically regulated osteoblast differentiation, we tested whether similar signaling was involved in mineralization by CVCs. In static cultures, pharmacological inhibition of the extracellular signal-regulated kinase (ERK1/2), p38 MAPK, and c-Jun N-terminal kinase pathways significantly attenuated mineral production by as much as −94%, compared with uninhibited CVCs. Strikingly, although mechanical stimulation activated each of the MAPK pathways, inhibition of these pathways had no effect on the mechanically induced enhancement of alkaline phosphatase activity or mineralization. These novel data indicate that mechanical signals regulate calcification by CVCs, and although MAPK signaling is critical to CVC osteogenic differentiation and mineralization, it is not involved directly in transduction of mechanical signals to regulate these processes under the conditions utilized in this study.
Particle migration, poor shape definition and/or rapid resorption limit the success of current urethral bulking agents. We propose that shape defining porous scaffolds that allow cell infiltration ...and anchoring, and may be delivered in a minimally invasive manner may provide many advantageous features.
Alginate hydrogels were prepared with varying degrees of covalent cross-linking and different pore characteristics. Dehydrated scaffolds were compressed into smaller, temporary forms, introduced into the dorsal subcutaneous space of CD-1 mice by minimally invasive delivery through a 10 gauge angiocatheter and rehydrated
in situ with a saline solution delivered through the same catheter. Ionically cross-linked calcium alginate gel served as a control. Specimens were harvested at 2, 6, 12 and 24 weeks to evaluate implant shape retention and volume, cell infiltration and calcification, and the presence of an inflammatory response.
A total of 90 scaffolds were implanted and 95% were recovered at the site of injection. All of these scaffolds successfully rehydrated and 80% recovered and maintained their original 3-dimensional shape for 6 months. Scaffold volume and tissue infiltration varied depending on the degree of alginate cross-linking. Highly cross-linked materials (20% and 35%) demonstrated the best volume maintenance with the latter facilitating the most tissue infiltration. The inflammatory response was minimal except with the 80% cross-linked material. Calcification was not observed in covalently cross-linked scaffolds. In contrast, 98% of calcium alginate implants were calcified.
Shape retaining porous hydrogels meet many of the requirements necessary for a successful injectable bulking agent and offer advantages over currently used agents.
This essay uses the Thistlewood family papers as a health record for the enslaved population in Jamaica. It examines the medical aspects of Thistlewood's journals, contextualising them in the social, ...political and cultural environment in the latter half of the eighteenth century. Examples of his provisions for medical care throughout his life are investigated systematically. Through counts from the original documents, the author identifies a seasonal pattern of disease and mortality on large and small Jamaican plantations and estimates an infant mortality rate of approximately 420 per 1000 births for Jamaican infants born into slavery.
Beginning in March 2020, case reports and case series linked the COVID-19 pandemic with an increased occurrence of chilblains, but this association has not been evaluated in an epidemiologic study.
...To assess whether a correlation exists between COVID-19 incidence and chilblains incidence.
A retrospective cohort study was conducted within the Kaiser Permanente Northern California system from January 1, 2016, to December 31, 2020; health plan members of all ages were included.
COVID-19 incidence in 207 location-months, representing 23 geographic locations in northern California across 9 months.
Chilblains incidence was the main outcome. The association of chilblains incidence with COVID-19 incidence across the 207 location-months was measured using the Spearman rank correlation coefficient.
Of 780 patients with chilblains reported during the pandemic, 464 were female (59.5%); mean (SD) age was 36.8 (21.8) years. COVID-19 incidence was correlated with chilblains incidence at 207 location-months (Spearman coefficient 0.18; P = .01). However, only 17 of 456 (3.7%) patients with chilblains tested during the pandemic were positive for SARS-CoV-2, and only 9 of 456 (2.0%) were positive for SARS-CoV-2 within 6 weeks of the chilblains diagnosis. Test results of 1 of 97 (1.0%) patients were positive for SARS-CoV-2 IgG antibodies. Latinx patients were disproportionately affected by COVID-19 but not by chilblains.
This cohort study found that in northern California, the incidence of chilblains increased during the pandemic but was correlated weakly with the incidence of COVID-19 across 207 location-months. These findings may have resulted from a causal role of COVID-19, increased care-seeking by patients with chilblains during the pandemic, or changes in behavior during shelter in place.
Penile prosthesis infections remain challenging despite advancements in surgical technique, device improvements, and adoption of antibiotic prophylaxis guidelines.
To investigate penile prosthesis ...infection microbiology to consider which changes in practice could decrease infection rates, to evaluate current antibiotic prophylaxis guidelines, and to develop a proposed algorithm for penile prosthesis infections.
This retrospective institutional review board-exempt multi-institutional study from 25 centers reviewed intraoperative cultures obtained at explantation or Mulcahy salvage of infected three-piece inflatable penile prostheses (IPPs). Antibiotic usage was recorded at implantation, admission for infection, and explantation or salvage surgery. Cultures were obtained from purulent material in the implant space and from the biofilm on the device.
Intraoperative culture data from infected IPPs.
Two hundred twenty-seven intraoperative cultures (2002-2016) were obtained at salvage or explantation. No culture growth occurred in 33% of cases and gram-positive and gram-negative organisms were found in 73% and 39% of positive cultures, respectively. Candida species (11.1%), anaerobes (10.5%) and methicillin-resistant Staphylococcus aureus (9.2%) constituted nearly one third of 153 positive cultures. Multi-organism infections occurred in 25% of positive cultures. Antibiotic regimens at initial implantation were generally consistent with American Urological Association (AUA) and European Association of Urology (EAU) guidelines. However, the micro-organisms identified in this study were covered by these guidelines in only 62% to 86% of cases. Antibiotic selection at admissions for infection and salvage or explantation varied widely compared with those at IPP implantation.
This study documents a high incidence of anaerobic, Candida, and methicillin-resistant S aureus infections. In addition, approximately one third of infected penile prosthesis cases had negative cultures. Micro-organisms identified in this study were not covered by the AUA and EAU antibiotic guidelines in at least 14% to 38% of cases. These findings suggest broadening antibiotic prophylaxis guidelines and creating a management algorithm for IPP infections might lower infection rates and improve salvage success. Gross MS, Phillips EA, Carrasquillo RJ, et al. Multicenter Investigation of the Micro-Organisms Involved in Penile Prosthesis Infection: An Analysis of the Efficacy of the AUA and EAU Guidelines for Penile Prosthesis Prophylaxis. J Sex Med 2017;14:455-463.
Research on the experience of receiving and living with a diagnosis of dementia is sparse. Existing studies have focused on the initial reactions to the diagnosis rather than longer term adjustment ...and coping. The current study uses interpretative phenomenological analysis to explore personal experiences of receiving a diagnosis and to investigate aspects of the experience of adjusting and adapting to dementia. This is a cross-sectional study drawing on semi-structured interviews with 10 participants who had a diagnosis of mild Alzheimer’s disease. The findings illustrated the importance, to people with Alzheimer’s disease, of understanding and making sense of the diagnosis to help them deal with issues of loss and to make positive adjustments to their lives through employing specific coping strategies. The findings also appeared to challenge misconceptions held by some professionals in relation to possible negative effects of disclosing a diagnosis of dementia.
The severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection is associated with increased levels of autoantibodies targeting immunological proteins such as cytokines and chemokines. ...Reports further indicate that COVID‐19 patients may develop a broad spectrum of autoimmune diseases due to reasons not fully understood. Even so, the landscape of autoantibodies induced by SARS‐CoV‐2 infection remains uncharted territory. To gain more insight, we carried out a comprehensive assessment of autoantibodies known to be linked to diverse autoimmune diseases observed in COVID‐19 patients in a cohort of 231 individuals, of which 161 were COVID‐19 patients (72 with mild, 61 moderate, and 28 with severe disease) and 70 were healthy controls. Dysregulated IgG and IgA autoantibody signatures, characterized mainly by elevated concentrations, occurred predominantly in patients with moderate or severe COVID‐19 infection. Autoantibody levels often accompanied anti‐SARS‐CoV‐2 antibody concentrations while stratifying COVID‐19 severity as indicated by random forest and principal component analyses. Furthermore, while young versus elderly COVID‐19 patients showed only slight differences in autoantibody levels, elderly patients with severe disease presented higher IgG autoantibody concentrations than young individuals with severe COVID‐19. This work maps the intersection of COVID‐19 and autoimmunity by demonstrating the dysregulation of multiple autoantibodies triggered during SARS‐CoV‐2 infection. Thus, this cross‐sectional study suggests that SARS‐CoV‐2 infection induces autoantibody signatures associated with COVID‐19 severity and several autoantibodies that can be used as biomarkers of COVID‐19 severity, indicating autoantibodies as potential therapeutical targets for these patients.
Within the social psychological understanding of dementia, individuals’ personhood is central. A respect for personhood has been linked to successful person-centred care, yet research exploring ...subjective personhood in dementia is scarce. This study aimed to understand personhood by exploring the subjective experiences of those with dementia. Seven individuals with dementia were interviewed and interpretative phenomenological analysis was used to identify themes across accounts. Themes identified were: (1) working out the system and adapting in order to survive it – the ‘peoplehood’ of the system; (2) using past and future roles and experiences to manage the present – the transient nature of personhood; (3) being both an individual and a member of a group − the conflict of a dual role. The themes highlighted showed that individuals with dementia supported their personhood by drawing on their own, others’ and the system’s resources. The findings are discussed and links with existing literature and clinical implications are considered.
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