Interstitial Environment Research Articles

Diagnostic Performance of Dynamic Contrast-Enhanced 3T MR Imaging for Characterization of Orbital Lesions: Validation in a Large Prospective Study.

Orbital lesions are rare but serious. Their characterization remains challenging. Diagnosis is based on biopsy or surgery, which implies functional risks. It is necessary to develop noninvasive diagnostic tools. The goal of this study was to evaluate the diagnostic performance of dynamic contrast-enhanced MR imaging at 3T when distinguishing malignant from benign orbital tumors on a large prospective cohort. This institutional review board-approved prospective single-center study enrolled participants presenting with an orbital lesion undergoing a 3T MR imaging before surgery from December 2015 to May 2021. Morphologic, diffusion-weighted, and dynamic contrast-enhanced MR images were assessed by 2 readers blinded to all data. Univariable and multivariable analyses were performed. To assess diagnostic performance, we used the following metrics: area under the curve, sensitivity, and specificity. Histologic analysis, obtained through biopsy or surgery, served as the criterion standard for determining the benign or malignant status of the tumor. One hundred thirty-one subjects (66/131 [50%] women and 65/131 [50%] men; mean age, 52 [SD, 17.1] years; range, 19-88 years) were enrolled. Ninety of 131 (69%) had a benign lesion, and 41/131 (31%) had a malignant lesion. Univariable analysis showed a higher median of transfer constant from blood plasma to the interstitial environment (K trans) and of transfer constant from the interstitial environment to the blood plasma (minute-1) (Kep) and a higher interquartile range of K trans in malignant-versus-benign lesions (1.1 minute-1 versus 0.65 minute-1, P = .03; 2.1 minute-1 versus 1.1 minute-1, P = .01; 0.81 minute-1 versus 0.65 minute-1, P = .009, respectively). The best-performing multivariable model in distinguishing malignant-versus-benign lesions included parameters from dynamic contrast-enhanced imaging, ADC, and morphology and reached an area under the curve of 0.81 (95% CI, 0.67-0.96), a sensitivity of 0.82 (95% CI, 0.55-1), and a specificity of 0.81 (95% CI, 0.65-0.96). Dynamic contrast-enhanced MR imaging at 3T appears valuable when characterizing orbital lesions and provides complementary information to morphologic imaging and DWI.

The Baget Karstic System and the Interstitial Environment of Lachein, a Hotspot of Subterranean Biodiversity in the Pyrenees (France)

Located in Lestelas-Balaguères massif, central northern Pyrenees, France, the Baget catchment covers 13.25 km2 and is highly karstified: so far, more than 80 caves have been recorded. The main outlet of the system, the exsurgence de Las Hountas, has an average flow of 550 L/s. Downstream, it is connected with the hyporheic of the Lachein stream. The Baget system, formed by both the karstic system and the hyporheic, has been intensively investigated by cave biologists and is known to be a hotspot for subterranean biodiversity. The synthesis provided here lists no less than 17 troglobionts and 40 stygobionts, with 3 single site endemics, making the Baget system the richest subterranean hotspot in the Pyrenees. This is notably due to the diversity of subterranean habitats and to the comprehensive knowledge of the stygofauna, likely unmatched at the European scale. Considering the significant speleological findings of the last 15 years that have not been yet biologically investigated, we can expect new discoveries, especially for the troglofauna.

NonB Cell-Derived Immunoglobulins in Intestinal Tract.

Intestinal epithelium constitutes a barrier to the unrestricted movement of pathogens, and other detrimental substances from the external world (gut lumen) into the interstitial environment. Intestinal epithelial cells obstruct harmful substances passing through the epithelium as a physical and chemical barrier; Moreover, the epithelial cells can express Toll-like receptors (TLRs) and cytokines to exert innate immune function. In addition, high levels of immunoglobulin A (IgA) and other antibodies exist in the intestinal mucosa, maintaining intestinal immune homeostasis in conjunction with intestinal probiotics. Traditionally, these antibodies have been deemed to be secreted by submucosal plasma cells. Nonetheless, in recent years, it has been demonstrated that intestinal epithelial cells produce a substantial amount of Igs, especially IgA or free Ig light chains, which are involved in intestinal immune homeostasis and the survival of normal epithelial cells. Furthermore, mounting evidence affirms that many human carcinoma cells, including colorectal cancer (CRC), can overexpress Igs, particularly IgG. Cancer-derived Igs exhibit a unique V(D)J rearrangement pattern distinct from B cell-derived Ig; moreover, this cancer cell-derived IgG also has a unique sialic acid modification on the 162 site of CH1 domain (SIA-IgG). The SIA-IgG plays a crucial role in promoting cancer initiation, progression, metastasis, and tumour immune escape. Simultaneously, CRC cells can also express free Ig light chains, which promote colitis, colitis-associated colon carcinogenesis, and CRC progression. Therefore, Igs expressed by CRC cells could be a potential target for diagnosing and preventing the transformation of inflammation into cancer, as well as treating CRC.

Connectivity of benthic marine ciliates assemblages in sandy beaches of south Bahia (Brazil)

Sandy beaches are predominant ecosystems in the coastal zone of Brazil. In the interstitial environment, several microscopic species called microbenthos are responsible for primary production, consumption of bacteria and decomposition processes. Ciliophora is one of the most diverse phylum within the microbenthos, although its diversity and ecological aspects are still underestimated. We selected 12 beach segments in the south coast of Bahia, northeastern Brazil, to verify the diversity and connectivity between open and extensive beaches and those isolated by rocky outcrops. We found 52 morphospecies distributed in 16 families of ciliates. Statistical analysis showed higher richness in open beaches when compared to isolated ones, that could be due to their extension area, low hydrodynamics and organic matter retention. Urbanization factor, when interacting with beach categories, affect ciliates species richness. In our samples, open beaches presented a higher number of ciliate families in comparison with isolated beaches, and urbanization seemed to influence these differences. Species composition analysis showed high connectivity of ciliate assemblages between the beaches sampled, without significant diferences. The diversity profile showed that open beaches have greater diversity in comparison with isolated beaches. Urbanization profiles did not show diferences in ciliate diversity. More studies on marine benthic ciliates diversity and their ecological aspects are needed to understand their distribution patterns and assemblage connectivity.

Locomotory Palp Function in Interstitial Annelids.

AbstractThe interstitial environment of marine sediments is a complex network of voids and pores that is inhabited by a diverse and abundant fauna. Animals living within these interstitial spaces show widespread functional adaptations to this environment and have developed many strategies for moving and navigating through small spaces. Interstitial annelids demonstrate a remarkable level of morphologic diversity, and some possess dexterous, filiform palps (tentacle-like appendages common across Annelida). The function(s) of these palps in interstitial spaces has not been closely examined, and we propose that they serve a sensory role in the navigation of interstitial spaces. We investigated the locomotory function of long, dexterous palps in three families of interstitial annelids to determine their role in interstitial navigation. We observed two species of protodrilids (Protodrilidae), Pharyngocirrus eroticus (Saccocirridae), and Protodorvillea recuperata (Dorvilleidae), as they moved through two transparent sand analogs: cyolite and glass beads. All four species of annelids consistently used their palps to probe the interstitial environment while locomoting, and the distance probed with their palps was greater than the distance traveled with their heads, indicating a sensory form of palp-based navigation. The functionality of palps as sensory organs in the interstitial environment raises interesting questions about interstitial navigation and how fauna without appendages map their surroundings. The discovery of this previously undocumented function was possible only through the direct observation of interstitial behavior and emphasizes the importance of developing new techniques to study these animals in more natural habitats.

Pathomorphological and pathochemical characteristic of the osteomyelitis focus in patients with diabetic osteoarthropathy (Charcot foot)

BACKGROUND: Osteomyelitis in diabetic osteoarthropathy occurs in 65 % of cases, and it is the main cause of non-traumatic amputations. The choice of optimal treatment technologies should be based on understanding the pathogenetic characteristics of this disease.AIM: To study the pathomorphological and pathochemical picture of osteomyelitic focus in patients with diabetic neuroosteoarthropathy.MATERIALS AND METHODS: Object — 20 patients (55.3±9.33 years) with Type 2 diabetes mellitus, diabetic neuroosteoarthropathy, chronic osteomyelitis of the foot bones. The treatment consisted in surgical debridement of the purulent focus with the material collection for pathomorphological and biochemical studies, and in reposition and alignment of bone fragments with the leg and foot fixation using the Ilizarov fixator in order to form bone ankylosis of the compromised joint.RESULTS: Subacute and acute course of chronic osteomyelitis was registered in 80 % of cases. As for the pathohistological changes in bone tissue, the following ones were the most significant: necrosis and the presence of an inflammatory infiltrate of varying severity depending on the phase of the inflammatory process. The articular cartilage structure was broken in all the cases. Activation of osteoclasts was observed in the osteomyelitis focus, especially in the subchondral zone. There was no subchondral bone plate in most cases, or only its fragments remained. Pathohistological examination of the soft tissues associated with the osteomyelitis focus indicated the presence of mirocirculatory and denervation disorders due to necrosis and hyalinosis of a significant part of microvessels against the background of compensatory hypervascularisation and chronic inflammation, narrowing and obliteration of the lumens of feeding arteries, almost complete absence of nerve elements in the tissues or their destructive changes. An increase in the activity of lytic enzymes was revealed in the interstitial environment of the tissues surrounding the osteomyelitis focus (138-fold increase in the activity of acid phosphatase, interstitial osteolytic index was 7.2-fold higher than blood serum index).CONCLUSION: The pathomorphological signs of chronic osteomyelitis subacute and acute processing were observed in most patients. Breaking the articular cartilage structure was accompanied by invasion of vessels, inflammatory infiltrate, and by activation of osteoclasts in the subchondral zone. Destructive changes of vessels and nerves in the soft tissues associated with the osteomyelitis focus can be etiopathogenetic factors of this disease development. The technologies for stopping this process should be based on obligatory debridement of the focus with sequestrnecrectomy, with regular monitoring of the operated segment condition.

Putative mechanobiological impact of surface texture on cell activity around soft-tissue implants undergoing micromotion.

Recent reports of adverse health effects (e.g., capsular contracture, lymphoma) linked to the absence or presence of texture on soft-tissue implants (e.g., breast implants) suggest surface topography may have pathological impact(s). We propose that surface texture influences the transfer of displacements, experienced by an implant undergoing micromotion, to surrounding interfacial extracellular matrix, which in turn impacts the activity of the resident cells and is based on degree of tissue integration. We hypothesize that transfer of displacements due to micromotion promotes interstitial fluid movement that imposes hydrodynamic stresses (pressures, shear stresses) on cells residing in the interfacial tissues and impacts their activity. To address this, we developed a computer simulation to approximate hydrodynamic stresses in the interstitial environment of saturated poroelastic tissues (model soft-tissue implantation sites) generated from oscillatory implant micromotion as a function of the magnitude of translational displacement, direction of motion, degree of tissue integration, and surface roughness of the implant. Highly integrated implants were predicted to generate the highest fluid shear stresses within model tissues, with oscillatory fluid shear stresses up to 80 dyn/cm2 for a 20-μm displacement. Notably, application of oscillatory 80 dyn/cm2 shear stress to cultured human fibroblasts elicited cell death after 20h compared to cells maintained under static conditions or exposed to 80 dyn/cm2 steady, unidirectional shear. These results indicate that oscillatory interstitial fluid stresses generated by micromotion of an integrated implant may influence the activity of the surrounding cells and play a role in the body's fibrotic response to textured soft-tissue implants.

Four new species of Ctenodrilus, Raphidrilus, and Raricirrus (Cirratuliformia, Annelida) in Japanese waters, with notes on their phylogenetic position.

Four new species of annelids, Ctenodrilus japonicus sp. nov., Raphidrilus misakiensis sp. nov., Raphidrilus okinawaensis sp. nov., and Raricirrus anubis sp. nov., are described based on specimens collected from Japanese waters. Ctenodrilus japonicus sp. nov. inhabits the interstitial environment and can be distinguished from the other congeners by the following features: (i) total of 16 chaetigers, (ii) chaetigers 1–3 with stout hooks, (iii) minute body (approximately 1 mm in length), (iv) all parapodia with the same number of chaetae (two notochaetae; two neurochaetae), and (v) presence of dorsal and ventral papillae. Raphidrilus misakiensis sp. nov. lives under intertidal stones and can be distinguished from other congeners by having pectinate neurochaetae. Raphidrilus okinawaensis sp. nov. inhabits the interstitial environment and can be distinguished from other congeners by: (i) absence of annulation on the peristomium and achaetous segment and (ii) presence of a heart body in chaetigers 4–5. Raricirrus anubis sp. nov. inhabits whale bones and can be distinguished from other congeners by the following features: (i) presence of a heart body in chaetigers 9–14, (ii) presence of capillary neurochaetae on chaetiger 1, and (iii) presence of simple curved spines. A phylogenetic tree based on partial sequences of cytochrome c oxidase subunit I and 16S rRNA from the new species and other cirratulid worms showed that Raphidrilus is included in Cirratuliformia. This is the first record of Raphidrilus and Raricirrus from Japanese waters.

Kidney Injury Causes Accumulation of Renal Sodium That Modulates Renal Lymphatic Dynamics.

Lymphatic vessels are highly responsive to changes in the interstitial environment. Previously, we showed renal lymphatics express the Na-K-2Cl cotransporter. Since interstitial sodium retention is a hallmark of proteinuric injury, we examined whether renal sodium affects NKCC1 expression and the dynamic pumping function of renal lymphatic vessels. Puromycin aminonucleoside (PAN)-injected rats served as a model of proteinuric kidney injury. Sodium 23Na/1H-MRI was used to measure renal sodium and water content in live animals. Renal lymph, which reflects the interstitial composition, was collected, and the sodium analyzed. The contractile dynamics of isolated renal lymphatic vessels were studied in a perfusion chamber. Cultured lymphatic endothelial cells (LECs) were used to assess direct sodium effects on NKCC1. MRI showed elevation in renal sodium and water in PAN. In addition, renal lymph contained higher sodium, although the plasma sodium showed no difference between PAN and controls. High sodium decreased contractility of renal collecting lymphatic vessels. In LECs, high sodium reduced phosphorylated NKCC1 and SPAK, an upstream activating kinase of NKCC1, and eNOS, a downstream effector of lymphatic contractility. The NKCC1 inhibitor furosemide showed a weaker effect on ejection fraction in isolated renal lymphatics of PAN vs controls. High sodium within the renal interstitium following proteinuric injury is associated with impaired renal lymphatic pumping that may, in part, involve the SPAK-NKCC1-eNOS pathway, which may contribute to sodium retention and reduce lymphatic responsiveness to furosemide. We propose that this lymphatic vessel dysfunction is a novel mechanism of impaired interstitial clearance and edema in proteinuric kidney disease.

Muscle fibrosis and maladaptation occur progressively in CKD and are rescued by dialysis.

BACKGROUNDSkeletal muscle maladaptation accompanies chronic kidney disease (CKD) and negatively affects physical function. Emphasis in CKD has historically been placed on muscle fiber–intrinsic deficits, such as altered protein metabolism and atrophy. However, targeted treatment of fiber-intrinsic dysfunction has produced limited improvement, whereas alterations within the fiber-extrinsic environment have scarcely been examined.METHODSWe investigated alterations to the skeletal muscle interstitial environment with deep cellular phenotyping of biopsies from patients with CKD and age-matched controls and performed transcriptome profiling to define the molecular underpinnings of CKD-associated muscle impairments. We examined changes in muscle maladaptation following initiation of dialysis therapy for kidney failure.RESULTSPatients with CKD exhibited a progressive fibrotic muscle phenotype, which was associated with impaired regenerative capacity and lower vascular density. The severity of these deficits was strongly associated with the degree of kidney dysfunction. Consistent with these profound deficits, CKD was associated with broad alterations to the muscle transcriptome, including altered ECM organization, downregulated angiogenesis, and altered expression of pathways related to stem cell self-renewal. Remarkably, despite the seemingly advanced nature of this fibrotic transformation, dialysis treatment rescued these deficits, restoring a healthier muscle phenotype. Furthermore, after accounting for muscle atrophy, strength and endurance improved after dialysis initiation.CONCLUSIONThese data identify a dialysis-responsive muscle fibrotic phenotype in CKD and suggest the early dialysis window presents a unique opportunity of improved muscle regenerative capacity during which targeted interventions may achieve maximal impact.TRIAL REGISTRATIONNCT01452412FUNDINGNIH, NIH Clinical and Translational Science Awards (CTSA), and Einstein-Mount Sinai Diabetes Research Center

Self-organising human gonads generated by a Matrigel-based gradient system

BackgroundAdvances in three-dimensional culture technologies have led to progression in systems used to model the gonadal microenvironment in vitro. Despite demonstrating basic functionality, tissue organisation is often limited. We have previously detailed a three-dimensional culture model termed the three-layer gradient system to generate rat testicular organoids in vitro. Here we extend the model to human first-trimester embryonic gonadal tissue.ResultsTesticular cell suspensions reorganised into testis-like organoids with distinct seminiferous-like cords situated within an interstitial environment after 7 days. In contrast, tissue reorganisation failed to occur when mesonephros, which promotes testicular development in vivo, was included in the tissue digest. Organoids generated from dissociated female gonad cell suspensions formed loosely organised cords after 7 days. In addition to displaying testis-specific architecture, testis-like organoids demonstrated evidence of somatic cell differentiation. Within the 3-LGS, we observed the onset of AMH expression in the cytoplasm of SOX9-positive Sertoli cells within reorganised testicular cords. Leydig cell differentiation and onset of steroidogenic capacity was also revealed in the 3-LGS through the expression of key steroidogenic enzymes StAR and CYP17A1 within the interstitial compartment. While the 3-LGS generates a somatic cell environment capable of supporting germ cell survival in ovarian organoids germ cell loss was observed in testicular organoids.ConclusionThe 3-LGS can be used to generate organised whole gonadal organoids within 7 days. The 3-LGS brings a new opportunity to explore gonadal organogenesis and contributes to the development of more complex in vitro models in the field of developmental and regenerative medicine.

Four new species of Parabathynellidae (Bathynellacea, Syncarida) from the interstitial environment of the Mekong River

ABSTRACT This paper describes and illustrates four new species of the parabathynellid genus Mekongbathynella Nam and Cho, 2014 (M. kampucheana sp. n., M. pienensis sp. n., M. jayavarmani sp. n. and M. jayavarthoni sp. n.) collected from the interstitial habitat of the Cambodian Mekong, thereby increasing the number of the known species of the genus to six. The species are clearly distinguished from each other in their general habitus and in the morphology of labrum, mandible, maxillule, male thoracopod VIII and anal operculum. The combination of these characteristics allows us to group the six species into two lineages; one lineage includes M. sesanensis Nam and Cho, 2014, M. kampucheana, M. pienensis (the lineage I), while the other one consists of M. kryi Nam and Cho, 2014, M. jayavarmani and M. jayavarthoni (the lineage II). Moreover, each species in a lineage occurs in sympatry with a species from the other lineage: M. sesanensis (lineage I) and M. kryi (lineage II), M. kampucheana (lineage I), and M. jayavarmani (lineage II) and M. pienensis (lineage I) and M. jayavarthoni (lineage II). The three areas where the species occur are placed in distinctive reaches and/or tributary of the Mekong displaying different hydrological conditions. urn:lsid:zoobank.org:pub:6C143F95-86D3-446E-9FE4-AE6B018F3128

Myoanatomy of three aberrant kinorhynch species: similar but different?

Aberrant kinorhynchs show several modifications deviating from the typical kinorhynch body plan, including a modified introvert with very elongated and flexible scalids, a weakly developed neck, and a slender trunk with less distinct segmentation. How these aberrant external features are reflected in the inner anatomy and how their aberrant body plan evolved are not understood. Here, we provide a comprehensive and comparative myoanatomical study of three putatively, distantly related worm-like species: Cateria styx, Franciscideres kalenesos and Zelinkaderes yong. Despite the weak external segmentation of the trunk, the studied species show a distinct segmental arrangement of the musculature. However, this arrangement is shifted posteriorly with respect to the external segmentation, because the extremely thin and flexible cuticle is lacking the apodeme-like cuticular thickenings (pachycycli) where the longitudinal muscles usually attach. The muscular arrangement in the three species is overall similar, yet, C. styx shows most resemblance to the allomalorhagid F. kalenesos, whereas the cyclorhagid Z. yong differs in several ways. This suggests a closer relationship of C. styx to Allomalorhagida. Whereas most kinorhynchs prefer muddy sediments, both the allomalorhagid and cyclorhagid worm-like kinorhynchs are mainly found in sandy environments, suggesting that a flexible, slender body evolved at least twice independently as an adaptation to the interstitial environment.

Interstitial Annelida

Members of the following marine annelid families are found almost exclusively in the interstitial environment and are highly adapted to move between sand grains, relying mostly on ciliary locomotion: Apharyngtidae n. fam., Dinophilidae, Diurodrilidae, Nerillidae, Lobatocerebridae, Parergodrilidae, Polygordiidae, Protodrilidae, Protodriloididae, Psammodrilidae and Saccocirridae. This article provides a review of the evolution, systematics, and diversity of these families, with the exception of Parergodrilidae, which was detailed in the review of Orbiniida by Meca, Zhadan, and Struck within this Special Issue. While several of the discussed families have previously only been known by a few described species, recent surveys inclusive of molecular approaches have increased the number of species, showing that all of the aforementioned families exhibit a high degree of cryptic diversity shadowed by a limited number of recognizable morphological traits. This is a challenge for studies of the evolution, taxonomy, and diversity of interstitial families as well as for their identification and incorporation into ecological surveys. By compiling a comprehensive and updated review on these interstitial families, we hope to promote new studies on their intriguing evolutionary histories, adapted life forms and high and hidden diversity.

Abstract 4263: Characterization of patient-specific drug delivery for breast cancer using image-guided computational fluid dynamics

Abstract Introduction: A tumor's blood supply and interstitial flow play an essential role in tumor growth, invasion, and treatment response. We have developed a methodology that employs quantitative MRI data to constrain a patient-specific, computational fluid dynamics (CFD) model of blood flow and interstitial transport within breast tumors. The dynamics of solute transport are characterized based on steady state flow fields, so that delivery of oxygen, nutrients, or therapies through the circulation can be estimated. It is a fundamentally new way to characterize breast tumor hemodynamics using MRI. Method: Eleven malignant and five benign lesions from 12 patients were included in this study. Vessel segmentation and tracking were performed to reconstruct the whole breast vasculature and to identify vessels feeding or draining tumors. Ultrafast dynamic contrast-enhanced MRI and diffusion-weighted imaging data were analyzed to estimate the bolus arrival time, Ktrans (volume transfer coefficient), and ADC (apparent diffusion coefficient); these data were used to spatially assign flow direction, local vascular permeability, and tissue density, respectively. The model of steady state flow was described by three components: 1) blood flow following Poiseuille's law, 2) interstitial flow following Darcy's law, and 3) flux transmitted across the vascular walls following Starling's law. The behavior of drug delivery was described by an advection-diffusion equation in the interstitial tissue, with the profile of the vascular bolus as a source term. The whole system was solved with a 1D-3D coupled implementation. At the end of analysis, the tracer's propagation through the tissue-of-interest was visualized and hemodynamic characteristics are derived to compare the malignant and benign lesions. Result: Visualization of the time-resolved distribution and propagation of solute demonstrated the intratumoral heterogeneity of accessibility to drugs. Furthermore, we are currently calculating the spatially-resolved accumulation, wash-in rate, and infiltration duration of different drugs for each lesion, so that a quantitative comparison can be performed between malignant and benign lesions. Conclusion: We have developed a computational model, informed by patient-specific MRI data, to simulate the blood supply, interstitial fluid environment, and intratumorally heterogeneous access to therapies for breast tumors. It represents the first methodology of integrating CFD with patient specific MRI data for quantifying the spatiotemporally resolved drug propagation as well as the entire pressure and flow fields within the breast. NCI U01CA142565, U01CA CA174706, and R01 CA218700. CPRIT RR160005. Citation Format: Chengyue Wu, David A. Hormuth, Federico Pineda, Gregory S. Karczmar, Robert D. Moser, Thomas E. Yankeelov. Characterization of patient-specific drug delivery for breast cancer using image-guided computational fluid dynamics [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4263.

Thermal injury initiates pervasive fibrogenesis in skeletal muscle.

Severe burn injury induces a myriad of deleterious effects to skeletal muscle, resulting in impaired function and delayed recovery. Following burn, catabolic signaling and myofiber atrophy are key fiber-intrinsic determinants of weakness; less well understood are alterations in the interstitial environment surrounding myofibers. Muscle quality, specifically alterations in the extracellular matrix (ECM), modulates force transmission and strength. We sought to determine the impact of severe thermal injury on adaptation to the muscle ECM and quantify muscle fibrotic burden. After a 30% total body surface area dorsal burn, spinotrapezius muscle was harvested from mice at 7 (7d, n = 5), 14 (14d, n = 4), and 21 days (21d, n = 4), and a sham control group was also examined (Sham, n = 4). Expression of transforming growth factor-β (TGFβ), myostatin, and downstream effectors and proteases involved in fibrosis and collagen remodeling were measured by immunoblotting, and immunohistochemical and biochemical analyses assessed fibrogenic cell abundance and collagen deposition. Myostatin signaling increased progressively through 21 days postburn alongside fibrogenic/adipogenic progenitor cell expansion, with abundance peaking at 14 days postburn. Postburn, elevated expression of tissue inhibitor of matrix metalloproteinase 1 supported collagen remodeling resulting in a net accumulation of muscle collagen content. Collagen accumulation peaked at 14 days postburn but remained elevated through 21 days postburn, demonstrating minimal resolution of burn-induced fibrosis. These findings highlight a progressive upregulation of fibrogenic processes following burn injury, eliciting a fibrotic muscle phenotype that hinders regenerative capacity and is not resolved with 21 days of recovery.

Deceleration of morphological evolution in a cryptic species complex and its link to paleontological stasis.

Morphological stasis or the absence of morphological change is a well-known phenomenon in the paleontological record, yet it is poorly integrated with neontological evidence. Recent evidence suggests that cryptic species complexes may remain morphologically identical due to morphological stasis. Here, we describe a case of long-term stasis in the Stygocapitella cryptic species complex (Parergodrilidae, Orbiniida, Annelida). Using phylogenetic methods and morphological data, we find that rates of morphological evolution in Stygocapitella are significantly slower than in closely related taxa (Nerillidae, Orbiniidae). Assessment of quantitative and qualitative morphology revealed the presence of four morphotypes with only subtle differences, whereas molecular data supports 10 reproductively isolated clades. Notably, estimates for the time of Stygocapitella species divergence range from ∼275 million years to ∼18 million years, including one case of two morphologically similar species that have diverged about 140 million years ago. These findings provide evidence for morphological deceleration and long-term morphological stasis in Stygocapitella, and that speciation is not necessarily accompanied by morphological changes. The deceleration of morphological divergence in Stygocapitella can be potentially linked to niche conservatism and tracking, coupled with the fluctuating dynamics of the interstitial environment, or genetic constraints due to progenetic evolution. Finally, we conclude that failing to integrate speciation without morphological evolution in paleontology may bias estimates of rates of speciation and morphological evolution.

The vascular endothelium plays a role in insulin action.

The endocrine system relies on the vasculature for delivery of hormones throughout the body, and the capillary microvasculature is the site where the hormones cross from the blood into the target tissue. Once considered an inert wall, various studies have now highlighted the functions of the capillary endothelium to regulate transport and therefore affect or maintain the interstitial environment. The role of the capillary may be clear in areas where there is a continuous endothelium, yet there also appears to be a role of endothelial cells in tissues with a sinusoidal structure. Here we focused on the most common endocrine disorder, diabetes, and several of the target organs associated with the disease, including skeletal muscle, liver and pancreas. However, it is important to note that the ability of hormones to cross the endothelium to reach their target tissue is a component of all endocrine functions. It is also a consideration in organs throughout the body and may have greater impact for larger hormones with target tissues containing a continuous endothelium. We noted that the blood levels do not always equal interstitial levels, which is what the cells are exposed to, and discussed how this may change in diseases such as obesity and insulin resistance. The capillary endothelium is, therefore, an essential and understudied aspect of endocrinology and metabolism that can be altered in disease, which may be an appropriate target for treatment.

Characterization of multilamellar bodies and telocytes within the testicular interstitium of naked mole rat Heterocephalus glabe

Multilamellar bodies (MLBs) are produced and secreted by many cell types. In this study, we report the existence and ultrastructure of MLBs that are produced by Leydig cells and identification of telocytes in the testicular interstitium of naked mole rat. This study was performed on both breeder and non-breeder male naked mole rats using light microscopy, transmission electron microscopy, and morphometric approaches. In the testicular interstitium, the most prominent cells were Leydig cells, which contained numerous lipid droplets (LDs) in the cytoplasm. We found that MLBs were associated with the LDs of Leydig cells and were secreted into the extracellular or interstitial environment via exocytosis. After their release from Leydig cells, MLBs localized to the space between Leydig cells near blood vessels and attached to telocytes. We also identified telocytes in the testicular interstitium, and their cellular extensions were distributed throughout the interstitium. MLBs were aligned along the cellular extensions of telocytes, and membrane-to-membrane contact was observed between the cellular extensions of telocytes and MLBs, suggesting that telocytes may play a role in the transport of MLBs within the interstitial space. No ultrastructural differences were found in Leydig cells, telocytes, or MLBs between breeder and non-breeder testes. However, morphometric analysis revealed a significant difference in the number of MLBs between the breeder and non-breeder animals. Furthermore, both selective autophagy of LDs and non-selective autophagy were observed in Leydig cells. Typical features of macrolipophagy were also observed, as a few LDs were entirely enclosed by a limiting membrane. Remarkably, autophagy may be a key factor in the biogenesis of MLBs and steroid hormone production. The appearance of MLBs in the testicular interstitium of naked mole rats could thus be related to lipid storage and trafficking.

Abstract 3629: Development of Combrestatin loaded vascular cell modified CLENS for targeting cellular models of tumor vascular endothelia in vitro

Abstract Purpose: The American Cancer Society predicts that about 0.6 million people would die of cancer and about 1.7 million new cases will be diagnosed in the year 2018. One important goal of cancer treatment is to minimize uptake of the cytotoxic drug agent by normal tissues. CLENs (cell membrane lipid-extracted nanoliposomes) have been developed to enhance targeted delivery of drugs to cancer cells located in the tumor interstitial matrix environment. The purpose of this study was to evaluate the use of CLENs for tumor vascular targeting. Methods: We expanded tumor endothelial cells derived from the pancreas followed by membrane extraction and the development of MS1-VEGF CLENs for vascular targeting. We evaluated the benefits of the additional inclusion of conventional liposome components (DOPC/Chol/DPPE-PEG5000) in various ratios, including the synthetic cationic lipid DOTAP (50 mol%), known for its vascular targeting characteristics when employed with conventional liposome components. We performed cellular uptake studies to determine relative level of selectivity in connection with the inclusion of LE (lipid extract) material. We determined also the effect of the additional inclusion of DOTAP in CLENs for targeting. We separated free drug from drug incorporated in CLENs using dialysis cassettes with MWCO of 10 kD. We evaluated the efficiency of Combrestatin A4 Phosphate (a microtubule-destabilizing agent) loading in CLENs by HPLC. Results: The addition of (50 mol%) cationic lipid DOTAP content in CLENs increased the overall zeta potential of the preparation from -14.26 ± 3.65 mV to 10.24 ± 4.23 mV. The average particle size for MS1-VEGF CLENs was approximately 137 ± 7 nm. The cellular uptake studies revealed that CLENs consisting of 70 mol% LE demonstrated the greatest selectivity towards MS1 VEGF cells, when compared to minimal uptake observed for non-target human glioblastoma (U87-MG) cell control. However, the data suggest also an overwhelming cationic lipid effect when DOTAP was included in the CLENs. Where overall cellular uptake increased, the selectivity afforded by LE decreased. Preliminary drug loading studies (between 20 and 45%) suggested that LE inclusion in nanoliposomes influenced the capacity for drug loading. Conclusion: The inclusion of MS1-VEGF lipid extract material in nanoliposomes improved vascular selectivity. The additional inclusion of DOTAP enhanced targeting, but the preference for target versus non-target cells had diminished. Additional studies are currently underway. Citation Format: Kanchi S. Sanghvi, Robert Campbell, Guang Yan. Development of Combrestatin loaded vascular cell modified CLENS for targeting cellular models of tumor vascular endothelia in vitro [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3629.