Myosin XI drives polarized growth by vesicle focusing and local enrichment of F-actin in Physcomitrium patens.

In tip-growing plant cells, growth results from myosin XI and F-actin-mediated deposition of cell wall polysaccharides contained in secretory vesicles. Previous evidence showed that myosin XI anticipates F-actin accumulation at the cell's tip, suggesting a mechanism where vesicle clustering via myosin XI increases F-actin polymerization. To evaluate this model, we used a conditional loss-of-function strategy by generating moss (Physcomitrium patens) plants harboring a myosin XI temperature-sensitive allele. We found that loss of myosin XI function alters tip cell morphology, vacuolar homeostasis, and cell viability but not following F-actin depolymerization. Importantly, our conditional loss-of-function analysis shows that myosin XI focuses and directs vesicles at the tip of the cell, which induces formin-dependent F-actin polymerization, increasing F-actin's local concentration. Our findings support the role of myosin XI in vesicle focusing, possibly via clustering and F-actin organization, necessary for tip growth, and deepen our understanding of additional myosin XI functions.

Pathogenic mechanisms and etiologic aspects of Mycobacterium avium subspecies paratuberculosis as an infectious cause of cutaneous melanoma.

Infectious etiologies have previously been proposed as causes of both melanoma and non-melanoma skin cancer. This exploratory overview explains and presents the evidence for the hypothesis that a microorganism excreted in infected ruminant animal feces, Mycobacterium avium subspecies paratuberculosis (MAP), is the cause of some cases of cutaneous melanoma (CM). Occupational, residential, and recreational contact with MAP-contaminated feces, soil, sand, and natural bodies of water may confer a higher rate of CM. Included in our hypothesis are possible reasons for the differing rates and locations of CM in persons with white versus nonwhite skin, why CM develops underneath nails and in vulvar skin, why canine melanoma is an excellent model for human melanoma, and why the Bacille Calmette-Guérin (BCG) vaccine has demonstrated efficacy in the prevention and treatment of CM. The pathogenic mechanisms and etiologic aspects of MAP, as a transmittable agent underlying CM risk, are carefully deliberated in this paper. Imbalances in gut and skin bacteria, genetic risk factors, and vaccine prevention/therapy are also discussed, while acknowledging that the evidence for a causal association between MAP exposure and CM remains circumstantial.

The evidence for Mycobacterium avium subspecies paratuberculosis (MAP) as a cause of nonsolar uveal melanoma: a narrative review.

Background and Objective: Animal microorganisms have been proposed as a cause of human cancers associated with farming, agricultural occupation or residence, and related downstream exposures. Several studies have described uveal melanoma (UvM) as a farming-associated cancer. A possible suspect is the animal microorganism Mycobacterium avium subspecies paratuberculosis (MAP), the causative agent of paratuberculosis in dairy cows. This microbe is transmitted to humans through various means, including contact with animal faeces, contaminated dust and soil, organic fertilizers, and as workers in slaughterhouses/animal processing facilities. The objective of the current manuscript was to examine the putative association between Mycobacterium avium sub-species paratuberculosis and non-solar UvM. Methods: Online data sources (PubMed, Scopus, Cochrane Library, and Google) published in English between 1980 to present were searched for key words pertaining to MAP exposure, farming-related occupations and activities, and locations with or in the vicinity of dairy cattle. Key Content and Findings: While higher than expected rates of eye cancer have been suggested among dairy farmers, with MAP being ubiquitous in their environment, the involvement of MAP in the aetiology of non-solar UvMs (which account for ~97% of UvM cases) remains uncertain. Conclusions: Alternative explanations exist and future cause-and-effect research is needed to answer this hypothesis. A precautionary approach to exposure continues to be a prudent strategy.

ALSUntangled #66: antimycobacterial antibiotics.

Several infections have been associated with motor neuron diseases resembling ALS, including species of viruses, bacteria, and parasites. Mycobacterium avium subspecies paratuberculosis (MAP), most known for its probable etiologic association with Crohn's disease, has been suggested as another possible infectious cause of motor neuron disease. Two published case reports describe the successful treatment of ALS-like symptoms with antimycobacterial antibiotics. Both cases had atypical features. Based on these, we believe it would be reasonable to begin performing chest imaging in PALS who have features of their history or exam that are atypical for ALS such as pain, fevers, or eye movement abnormalities. If the chest imaging is abnormal, more specific testing for mycobacteria may be indicated. Until there is more clear evidence of an association between mycobacteria and ALS, we cannot endorse the widespread use of potentially toxic antimycobacterial antibiotics for PALS.

Impacts of Prosthetic Innovation in Ecuador Study Abroad Course.

Biomedical engineering (BME) students typically have a schedule filled with specific course requirements, leaving little room for spending a semester studying abroad. We established a new short-term BME study abroad course, partnering with a non-profit healthcare organization that provides high-quality prosthetic care to underserved populations. This innovative study abroad course was met with great student demand. The impact of this short-term study abroad course is increased by developing year-long BME senior capstone design projects based on the needs identified throughout the experience in Ecuador. Shortly after the conclusion of spring semester, students and two BME faculty/staff traveled to Ecuador. During the work week, the students participated in small teams in patient evaluations, castings, fabrication of prosthetics, device fittings, rapid prototyping-testing iterations, and post-prosthesis gait training with physical therapy. Weekends included guided cultural activities. Each student maintained a journal that reflected observations and insights from these experiences. Upon return to the US, students that registered for an additional course credit created video reflection presentations and wrote project proposal reports based on the needs identified in Ecuador. The project proposal reports were used to develop a BME senior capstone design project. Pre and post course self-assessment surveys showed significant increases in five ABET learning outcomes, three BME learning outcomes, and four course-specific learning outcomes. Students who took the two-credit course reported significant increases in four more learning outcomes than students who took the one-credit course. Many students described the experience as inspiring and life-changing, and the program continues to run each summer.

Where are all the Mycobacterium avium subspecies paratuberculosis in patients with Crohn's disease?

Mycobacterium avium subspecies paratuberculosis (MAP) causes a chronic granulomatous inflammation of the intestines, Johne's disease, in dairy cows and every other species of mammal in which it has been identified. MAP has been identified in the mucosal layer and deeper bowel wall in patients with Crohn's disease by methods other than light microscopy, and by direct visualization in small numbers by light microscopy. MAP has not been accepted as the cause of Crohn's disease in part because it has not been seen under the microscope in large numbers in the intestines of patients with Crohn's disease. An analysis of the literature on the pathology of Crohn's disease and on possible MAP infection in Crohn's patients suggests that MAP might directly infect endothelial cells and adipocytes and cause them to proliferate, causing focal obstruction within already existing vessels (including granuloma formation), the development of new vessels (neoangiogenesis and lymphangiogenesis), and the "creeping fat" of the mesentery that is unique in human pathology to Crohn's disease but also occurs in bovine Johne's disease. Large numbers of MAP might therefore be found in the mesentery attached to segments of intestine affected by Crohn's disease rather than in the bowel wall, the blood and lymphatic vessels running through the mesentery, or the mesenteric fat itself. The walls of fistulas might result from the neoangiogenesis or lymphangiogenesis that occurs in the bowel wall in Crohn's disease and therefore are also possible sites of large numbers of MAP. The direct visualization of large numbers of MAP organisms in the tissues of patients with Crohn's disease will help establish that MAP causes Crohn's disease.

Baseballs, tennis balls, livestock farm manure, the IDH1 mutation, endothelial cell proliferation and hypoxic pseudopalisading (granulomatous) necrosis: Mycobacterium avium subspecies paratuberculosis and the epidemiology, cellular metabolism and histology of diffuse gliomas, including glioblastoma.

An increased rate of diffuse gliomas, including glioblastoma, has been noted in livestock farmers in Western countries. Some researchers have suggested that a zoonotic virus or bacteria present in the livestock animal's feces or manure may be a possible etiologic factor. Mycobacterium avium subspecies paratuberculosis (MAP), the cause of a chronic enteropathy in domestic livestock and a probable zoonosis, is heavily excreted in an infected animal's feces or manure, contaminating soil and ground on the animal's farm. Once excreted in an animal's feces, MAP lasts indefinitely in a dormant but viable form, and easily spreads outside farms to the surrounding environment. MAP's presence throughout the soil in countries where MAP infection of domestic livestock is extensive and long-standing may explain the increased rates of glioblastoma in tennis and baseball players who handle balls coated with MAP-contaminated dirt. MAP infection is consistent with glioblastoma's two defining histopathologic characteristics: endothelial cell proliferation and pseudopalisading necrosis. MAP is a non-tuberculous or atypical mycobacterium, which can cause hypoxic necrotizing granulomas, granulomas that resemble areas of pseudopalisading necrosis. There are known bacterial causes of endothelial cell proliferation. Almost unique amongst intracellular bacteria, MAP's variant isocitrate dehydrogenase 1 (IDH1) enzyme, a type 2-oxoglutarate ferredoxin oxidoreductase, can use a host cell's cytosolic α-ketoglutarate in its own Krebs or tricarboxylic acid cycle. MAP's ability to use a host cell's α-ketoglutarate may explain the survival advantage of the cytosolic IDH1 enzyme mutation for patients with diffuse gliomas including glioblastoma, astrocytoma, and oligdendroglioma, a mutation that results in a reduced supply of cytosolic α-ketoglutarate. MAP may therefore be one possible infectious cause of glioblastoma and the other histologic categories of diffuse glioma.

How did Lou Gehrig get Lou Gehrig's disease? Mycobacterium avium subspecies paratuberculosis in manure, soil, dirt, dust and grass and amyotrophic lateral sclerosis (motor neurone disease) clusters in football, rugby and soccer players.

There are several suspected infectious causes of amyotrophic lateral sclerosis (ALS) or motor neurone disease including HIV-1 and species of Brucella, Cyanobacteria and Schistosoma. The increased rates and clusters of ALS in amateur and professional outdoor sports players including rugby, football and soccer players suggest a microorganism present in the grass, dirt and dust they play on and in may be a causative factor. The probable zoonosis Mycobacterium avium subspecies paratuberculosis (MAP) is heavily excreted in an infected domestic ruminant's feces or manure and is extensively distributed throughout the soil in countries where MAP infection of domestic livestock is longstanding. Like other zoonotic pathogens, MAP can be transmitted to humans by inhalation of aerosolized pathogen-contaminated soil, by direct contact of pathogen-contaminated grass, dirt and dust with mucus membranes lining the nose or mouth or through abrasions and cuts in the skin. Outdoor sports players may develop ALS after multiple oral, nasal or subcutaneous doses of MAP present in the dirt, dust and grass of their playing fields.

Could Mycobacterium avium subspecies paratuberculosis cause Crohn's disease, ulcerative colitis and colorectal cancer?

Infectious agents are known causes of human cancers. Schistosoma japonicum and Schistosoma mansoni cause a percentage of colorectal cancers in countries where the respective Schistosoma species are prevalent. Colorectal cancer is a complication of ulcerative colitis and colonic Crohn's disease, the two main forms of idiopathic inflammatory bowel disease (IIBD). Mycobacterium avium subspecies paratuberculosis (MAP), the cause of a chronic intestinal disease in domestic and wild ruminants, is one suspected cause of IIBD. MAP may therefore be involved in the pathogenesis of IIBD-associated colorectal cancer as well as colorectal cancer in individuals without IIBD (sporadic colorectal cancer) in countries where MAP infection of domestic livestock is prevalent and MAP's presence in soil and water is extensive. MAP organisms have been identified in the intestines of patients with sporadic colorectal cancer and IIBD when high magnification, oil immersion light microscopy (×1000 total magnification rather than the usual ×400 total magnification) is used. Research has demonstrated MAP's ability to invade intestinal goblet cells and cause acute and chronic goblet cell hyperplasia. Goblet cell hyperplasia is the little-recognized initial pathologic lesion of sporadic colorectal cancer, referred to as transitional mucosa, aberrant crypt foci, goblet cell hyperplastic polyps or transitional polyps. It is the even lesser-recognized initial pathologic feature of IIBD, referred to as hypermucinous mucosa, hyperplastic-like mucosal change, serrated epithelial changes, flat serrated changes, goblet cell rich mucosa or epithelial hyperplasia. Goblet cell hyperplasia is the precursor lesion of adenomas and dysplasia in the classical colorectal cancer pathway, of sessile serrated adenomas and serrated dysplasia in the serrated colorectal cancer pathway, and of flat and elevated dysplasia and dysplasia-associated lesions or masses in IIBD-associated intestinal cancers. MAP's invasion of intestinal goblet cells may result in the initial pathologic lesion of IIBD and sporadic colorectal cancer. MAP's persistence in infected intestines may result in the eventual development of both IIBD-associated and sporadic colorectal cancer.

The Consensus from the Mycobacterium avium ssp. paratuberculosis (MAP) Conference 2017.

On March 24 and 25, 2017 researchers and clinicians from around the world met at Temple University in Philadelphia to discuss the current knowledge of Mycobacterium avium ssp. paratuberculosis (MAP) and its relationship to human disease. The conference was held because of shared concern that MAP is a zoonotic bacterium that poses a threat not only to animal health but also human health. In order to further study this problem, the conferees discussed ways to improve MAP diagnostic tests and discussed potential future anti-MAP clinical trials. The conference proceedings may be viewed on the www.Humanpara.org website. A summary of the salient work in this field is followed by recommendations from a majority of the conferees.

Developing an in situ forming polyphosphate coacervate as a new liquid embolic agent: From experimental design to pilot animal study.

A radiopaque temporary liquid embolic agent was synthesized from polyphosphate (PP) coacervates and optimized using a design of experiments approach. Variables studied were: strontium substitution (0-15 mol%), barium substitution (0-15 mol%), PP concentration and degree of polymerization of the polyphosphate (Dp). The viscosity, radiopacity and cell viability of the resulting coacervates were measured for 60 formulations and response surface modeling was used to determine the optimum coacervate that maximized radiopacity and cell viability. The optimum coacervate made from PP with a large Dp (9.5 g NaPP/100mL, 2.2 mol% Sr, 9 mol% Ba and 3.8 mol% Ca) was taken forward to a pilot animal trial. In this rabbit model, PP embolic agent successfully occluded the central auricular artery with promising biocompatibility. Further study is required to optimize the cohesiveness and clinical effectiveness of PP as an in situ setting temporary embolic agent. STATEMENT OF SIGNIFICANCE: This article describes the development of a new radiopaque temporary liquid embolic agent from the optimization using design of experiments to a pilot animal study. Embolization is a minimally invasive interventional radiology procedure used to block blood flow in a targeted blood vessel. This procedure is used to treat many conditions including: tumors, aneurysms and arteriovenous malformations. Currently, no inherent radiopaque embolic agents are available in the clinic, which would allow for direct imaging of the material during the procedure and follow up treatment.

Macrophage-like U937 cells recognize collagen fibrils with strain-induced discrete plasticity damage.

At its essence, biomechanical injury to soft tissues or tissue products means damage to collagen fibrils. To restore function, damaged collagen must be identified, then repaired or replaced. It is unclear at present what the kernel features of fibrillar damage are, how phagocytic or synthetic cells identify that damage, and how they respond. We recently identified a nanostructural motif characteristic of overloaded collagen fibrils that we have termed discrete plasticity. In this study, we have demonstrated that U937 macrophage-like cells respond specifically to overload-damaged collagen fibrils. Tendons from steer tails were bisected, one half undergoing 15 cycles of subrupture mechanical overload and the other serving as an unloaded control. Both halves were decellularized, producing sterile collagen scaffolds that contained either undamaged collagen fibrils, or fibrils with discrete plasticity damage. Matched-pairs were cultured with U937 cells differentiated to a macrophage-like form directly on the substrate. Morphological responses of the U937 cells to the two substrates-and evidence of collagenolysis by the cells-were assessed using scanning electron microscopy. Enzyme release into medium was quantified for prototypic matrix metalloproteinase-1 (MMP-1) collagenase, and MMP-9 gelatinase. When adherent to damaged collagen fibrils, the cells clustered less, showed ruffled membranes, and frequently spread: increasing their contact area with the damaged substrate. There was clear structural evidence of pericellular enzymolysis of damaged collagen-but not of control collagen. Cells on damaged collagen also released significantly less MMP-9. These results show that U937 macrophage-like cells recognize strain-induced discrete plasticity damage in collagen fibrils: an ability that may be important to their removal or repair.

Riboflavin-sensitized photo-crosslinking of collagen using a dental curing light.

BACKGROUND: Photo-crosslinking of biomolecules such as collagen and fibrinogen is an emerging area of research interest. The use of a small dental curing light with a non-toxic photosensitizer represents a novel, practical approach to periodontal wound treatment. OBJECTIVE: This study evaluated the effects of riboflavin-sensitized photo-oxidation using a dental curing light on two collagenous biomaterials, as a preliminary step towards developing a medical technology for wound closure/healing. METHODS: A collagenous biomaterial (DBP) and type I collagen gels were treated by this photo-oxidative technique and characterized by hydrothermal isometric tension (HIT) analysis, amino acid analysis, SDS-PAGE, and rheology. RESULTS: HIT analysis suggested that dental curing light exposure for 300 s with riboflavin produced heavily crosslinked DBP. Dental curing light exposure for 300 s with riboflavin also showed a reduction in lysine concentration of DBP. SDS-PAGE showed that dental curing light exposure for 30 or 300 s with riboflavin resulted in crosslinked collagen gels. Dental curing light exposure for 30 s with riboflavin yielded a collagen gel with the strongest rheological characteristics. CONCLUSIONS: This novel approach to wound treatment has potential for wide adoption and clinical use, particularly because dental curing lights, riboflavin, and collagen biomaterials are all used clinically, but not yet combined together as one technology for broad application.

Interactions of U937 macrophage-like cells with decellularized pericardial matrix materials: influence of crosslinking treatment.

While macrophages have been implicated in the failure of bioprosthetic heart valves, the macrophage response to crosslinked native pericardial collagen has not been previously investigated. Using decellularized bovine pericardium (DBP) as a model for native collagen, this study investigated the response of macrophage-like cells (U937s) to DBP, either: (i) untreated, or (ii) exogenously crosslinked with glutaraldehyde or 1-ethyl-3-(3-dimethyl-aminopropyl)-carbodiimide (EDC). We have previously validated the use of U937 cells as models for the response of human monocyte-derived macrophages to decellularized pericardial materials and, per our previous work, differentiated the U937 cells directly on the three material surfaces. After 72h in culture, the cells and medium were analyzed for DNA content, acid phosphatase activity, and cytokine and matrix metalloproteinase release. As well, cell/substrate samples were fixed for SEM. Fewer cells attached to or survived on the glutaraldehyde-treated substrate, and some showed an abnormal morphology compared to cells cultured on the other surfaces. Further, cells on glutaraldehyde-treated surfaces released more pro-inflammatory cytokines, more MMP-1 and less MMP-2 and MMP-9. The poor performance of the U937 macrophage-like cells on the glutaraldehyde-treated surfaces appears to be due to surface characteristics rather than to soluble aldehyde or other components leaching from the crosslinked material. These results provide evidence that crosslinking with glutaraldehyde is cytotoxic to macrophage-like cells, and that crosslinking with a zero-length crosslinker like EDC can be an acceptable alternative crosslinking treatment for biomaterials.

Free-ranging Rocky Mountain bighorn sheep and an outbreak of inflammatory bowel disease along the Clark Fork River in Plains, Montana.

Nine individuals with ulcerative colitis or Crohn disease grew up or lived in Plains, Montana, a 1,200-person community adjacent to the Clark Fork River near herds of free ranging Rocky Mountain bighorn sheep. This inflammatory bowel disease outbreak is similar to others that have occurred along rivers contaminated by animal feces.

An elastomeric patch electrospun from a blended solution of dermal extracellular matrix and biodegradable polyurethane for rat abdominal wall repair.

A biodegradable elastomeric scaffold was created by electrospinning a mixed solution of poly(ester urethane)urea (PEUU) and porcine dermal extracellular matrix (dECM) digest, with PEUU included to provide elasticity, flexibility, and mechanical support and dECM used to enhance bioactivity and biocompatibility. Micrographs and differential scanning calorimetry demonstrated partial miscibility between PEUU and dECM. With greater dECM content, scaffolds were found to possess lower breaking strains and suture retention strength, although initial modulus was greater with higher dECM concentrations. The hybrid scaffolds containing 0% to 50% dECM had tensile strengths of 5 to 7 MPa, breaking strains of 138% to 611%, initial moduli of 3 to 11 Mpa, and suture retention strengths of 35 to 59 MPa. When hydrated, scaffolds were found to contract markedly with 50% dECM content. When used in a rat full-thickness abdominal wall replacement model, no herniation, infection, or tissue adhesion was observed after 4 and 8 weeks with a scaffold containing 25% dECM or a control 100% PEUU scaffold. Scaffolds incorporating dECM were significantly thicker at the time of explant, with greater numbers of associated smooth muscle actin-positive staining cells than in the control, but minimal cellular infiltration and remodeling of the scaffold were detected regardless of dECM addition. The processing of dECM and PEUU from a mixed solution thus provided a scaffold with evidence of better bioactivity and with mechanical properties not achievable with digested dECM alone.

A hydrogel derived from decellularized dermal extracellular matrix.

The ECM of mammalian tissues has been used as a scaffold to facilitate the repair and reconstruction of numerous tissues. Such scaffolds are prepared in many forms including sheets, powders, and hydrogels. ECM hydrogels provide advantages such as injectability, the ability to fill an irregularly shaped space, and the inherent bioactivity of native matrix. However, material properties of ECM hydrogels and the effect of these properties upon cell behavior are neither well understood nor controlled. The objective of this study was to prepare and determine the structure, mechanics, and the cell response in vitro and in vivo of ECM hydrogels prepared from decellularized porcine dermis and urinary bladder tissues. Dermal ECM hydrogels were characterized by a more dense fiber architecture and greater mechanical integrity than urinary bladder ECM hydrogels, and showed a dose dependent increase in mechanical properties with ECM concentration. In vitro, dermal ECM hydrogels supported greater C2C12 myoblast fusion, and less fibroblast infiltration and less fibroblast mediated hydrogel contraction than urinary bladder ECM hydrogels. Both hydrogels were rapidly infiltrated by host cells, primarily macrophages, when implanted in a rat abdominal wall defect. Both ECM hydrogels degraded by 35 days in vivo, but UBM hydrogels degraded more quickly, and with greater amounts of myogenesis than dermal ECM. These results show that ECM hydrogel properties can be varied and partially controlled by the scaffold tissue source, and that these properties can markedly affect cell behavior.

The Broad Street pump revisited: dairy farms and an ongoing outbreak of inflammatory bowel disease in Forest, Virginia.

We report an ongoing outbreak of ulcerative colitis and Crohn's disease in Forest, Virginia involving 15 unrelated children and teenagers who resided in close proximity to dairy farms. Some of our cases demonstrated serologic evidence of Mycobacterium avium subspecies paratuberculosis infection, suggesting its potential role as an etiologic agent.

Ulcerative colitis and Crohn's disease: is Mycobacterium avium subspecies paratuberculosis the common villain?

Mycobacterium avium, subspecies paratuberculosis (MAP) causes a chronic disease of the intestines in dairy cows and a wide range of other animals, including nonhuman primates, called Johne's ("Yo-knee's") disease. MAP has been consistently identified by a variety of techniques in humans with Crohn's disease. The research investigating the presence of MAP in patients with Crohn's disease has often identified MAP in the "negative" ulcerative colitis controls as well, suggesting that ulcerative colitis is also caused by MAP. Like other infectious diseases, dose, route of infection, age, sex and genes influence whether an individual infected with MAP develops ulcerative colitis or Crohn's disease. The apparently opposite role of smoking, increasing the risk of Crohn's disease while decreasing the risk of ulcerative colitis, is explained by a more careful review of the literature that reveals smoking causes an increase in both diseases but switches the phenotype from ulcerative colitis to Crohn's disease. MAP as the sole etiologic agent of both ulcerative colitis and Crohn's disease explains their common epidemiology, geographic distribution and familial and sporadic clusters, providing a unified hypothesis for the prevention and cure of the no longer "idiopathic" inflammatory bowel diseases.