Abnormal infant islet morphology precedes insulin resistance in PCOS-like monkeys.

Polycystic ovary syndrome (PCOS) is prevalent in reproductive-aged women and confounded by metabolic morbidities, including insulin resistance and type 2 diabetes. Although the etiology of PCOS is undefined, contribution of prenatal androgen (PA) exposure has been proposed in a rhesus monkey model as premenopausal PA female adults have PCOS-like phenotypes in addition to insulin resistance and decreased glucose tolerance. PA female infants exhibit relative hyperinsulinemia, suggesting prenatal sequelae of androgen excess on glucose metabolism and an antecedent to future metabolic disease. We assessed consequences of PA exposure on pancreatic islet morphology to identify evidence of programming on islet development. Islet counts and size were quantified and correlated with data from intravenous glucose tolerance tests (ivGTT) obtained from dams and their offspring. Average islet size was decreased in PA female infants along with corresponding increases in islet number, while islet fractional area was preserved. Infants also demonstrated an increase in both the proliferation marker Ki67 within islets and the beta to alpha cell ratio suggestive of enhanced beta cell expansion. PA adult females have reduced proportion of small islets without changes in proliferative or apoptotic markers, or in beta to alpha cell ratios. Together, these data suggest in utero androgen excess combined with mild maternal glucose intolerance alter infant and adult islet morphology, implicating deviant islet development. Marked infant, but subtle adult, morphological differences provide evidence of islet post-natal plasticity in adapting to changing physiologic demands: from insulin sensitivity and relative hypersecretion to insulin resistance and diminished insulin response to glucose in the mature PCOS-like phenotype

First description of seagrass distribution and abundance in Sao Tome and Principe

Seagrass meadows in Sao Tome and Principe, eastern Atlantic Ocean, are described here for the first time. Specifically, we quantified the biomass and density of seagrasses, characterized the plant morphology and measure their nutrient content as a proxy of the nutrient environmental conditions where the meadows develop. The seagrass Halodule wrightii was found in two locations of the northeastern coast of the island of Sao Tome: 1) developing throughout an estimated area of 1500 ha surrounding Cabras islet, at a depth range of 4-10 m, on sandy bottom; and 2) at Santana bay with an area of 1500 m(2) at 5-10 m depth, on sandy bottom. A highly morphologically different population of Halodule wrightii was found on the northeastern coast of the island of Principe, off Abade beach, covering an area of 135 m2 at 4 m depth. Further research is needed to assess if this is a different species. Shoot biomass and density was 10 and 4-fold higher in Sao Tome than in Principe, respectively. CN ratios of above and belowground tissues of plants collected in Sao Tome were also significantly higher than in Principe. The carbon content of Halodule leaves from Sao Tome and Principe (41%) was much higher than that reported for other Halodule species, suggesting that meadows may have an important ecological role for carbon fixation. The presence of H. wrightii in Sao Tome and Principe raises ecological and evolutionary questions that warrant further research.PADI Foundation [21670

Morphology of the recently re-classified Tasman masked booby (Sula dactylatra tasmani) breeding on the Kermadec Islands

Once thought to be extinct, the Tasman Booby Sula tasmani has recently been re-classified as a subspecies of the Masked Booby S. dactylatra on the basis of genetic data. This re-classification raises the issue of whether this novel clade has a distinct morphology. Morphological differences in size, as well as coloration of integuments, bill and iris have been found in other subspecies of the Masked Booby but have not yet been reported for live Kermadec Islands breeding individuals. Museum specimens from this breeding location have been separated from other Pacific breeding subspecies by their longer wings. We sampled a total of 21 individuals from North Meyer Islet, Kermadec Group, New Zealand, and applied molecular sexing to obtain sex-specific morphometric measurements. We matched dimorphism in vocalization with genetic sexing results and photographic documentation of human-assessed bill, foot and eye coloration. While culmen measurements were consistent with reports from museum specimens, wing chords from living specimens of Tasman Masked Boobies were 3% and 4% larger in males and females, respectively. Females had larger culmens and wings than males, consistent with the low extent of sexual dimorphism reported from museum skins. Adult Tasman Masked Boobies had yellow to buff-yellow feet, while fledglings, as in most sulids, had grey to greyish-yellow feet. Our findings confirm the distinctively long wing and particular iris coloration previously reported for the taxon and provide the first description of integument coloration of live specimens. This study highlights the importance of including in situ assessment in taxon descriptions

Islet isolation assessment in man and large animals

Recent progress in islet isolation from the pancreas of large mammals including man, accentuated the need for the development of precise and reproducible techniques to assess islet yield. In this report both quantitative and qualitative criteria for islet isolation assessment were discussed, the main topics being the determination of number, volume, purity, morphologic integrity and in vitro and in vivo function tests of the final islet preparations. It has been recommended that dithizone should be used as a specific stain for immediate detection of islet tissue making it possible to estimate both the total number of islets (dividing them into classes of 50 μ diameter range increments) and the purity of the final preparation. Appropriate morphological assessment should include confirmation of islet identification, assessment of the morphological integrity and of the purity of the islet preparation. The use of fluorometric inclusion and exclusion dyes together have been suggested as a viability assay to simultaneously quantitate the proportion of cells that are intact or damaged. Perifusion of islets with glucose provides a dynamic profile of glucose-mediated insulin release and of the ability of the cells to down regulate insulin secretion after the glycemic challenge is interrupted. Although perifusion data provides a useful guide to islet viability the quantity and kinetics of insulin release do not necessarily predict islet performance after implantation. Therefore, the ultimate test of islet viability is their function after transplantation into a diabetic recipient. For this reason, in vivo models of transplantation of an aliquot of the final islet preparation into diabetic nude (athymic) rodents have been suggested. We hope that these general guidelines will be of assistance to standardize the assessment of islet isolations, making it possible to better interpret and compare procedures from different centers. © 1990 Casa Editrice il Ponte

A role for von Hippel-Lindau protein in pancreatic beta-cell function.

ObjectiveThe Vhlh gene codes for the von Hippel-Lindau protein (VHL), a tumor suppressor that is a key player in the cellular response to oxygen sensing. In humans, a germline mutation in the VHL gene leads to the von Hippel-Lindau disease, a familial syndrome characterized by benign and malignant tumors of the kidney, central nervous system, and pancreas.Research design and methodsWe use Cre-lox recombination to eliminate Vhlh in adult mouse pancreatic beta-cells. Morphology of mutant islets is assessed by immunofluorescence analysis. To determine the functional state of Vhlh(-/-) islets, insulin secretion is measured in vivo and in vitro, and quantitative PCR is used to identify changes in gene expression.ResultsLoss of VHL in beta-cells leads to a severe glucose-intolerant phenotype in adult animals. Although VHL is not required for beta-cell specification and development, it is critical for beta-cell function. Insulin production is normal in beta-cells lacking VHL; however, insulin secretion in the presence of high concentrations of glucose is impaired. Furthermore, the loss of VHL leads to dysregulation of glycolytic enzymes, pointing to a perturbation of the intracellular energy homeostasis.ConclusionsWe show that loss of VHL in beta-cells leads to defects in glucose homeostasis, indicating an important and previously unappreciated role for VHL in beta-cell function. We believe that the beta-cell-specific Vhlh-deficient mice might be a useful tool as a "genetic hypoxia" model, to unravel the possible link between hypoxia signaling and impairment of beta-cell function

Lymphangiogenesis and angiogenesis during human fetal pancreas development

Background: The complex endocrine and exocrine functionality of the human pancreas depends on an efficient fluid transport through the blood and the lymphatic vascular systems. The lymphatic vasculature has key roles in the physiology of the pancreas and in regulating the immune response, both important for developing successful transplantation and cell-replacement therapies to treat diabetes. However, little is known about how the lymphatic and blood systems develop in humans. Here, we investigated the establishment of these two vascular systems in human pancreas organogenesis in order to understand neovascularization in the context of emerging regenerative therapies. Methods: We examined angiogenesis and lymphangiogenesis during human pancreas development between 9 and 22 weeks of gestation (W9-W22) by immunohistochemistry. Results: As early as W9, the peri-pancreatic mesenchyme was populated by CD31-expressing blood vessels as well as LYVE1- and PDPN-expressing lymphatic vessels. The appearance of smooth muscle cell-coated blood vessels in the intra-pancreatic mesenchyme occurred only several weeks later and from W14.5 onwards the islets of Langerhans also became heavily irrigated by blood vessels. In contrast to blood vessels, LYVE1- and PDPN-expressing lymphatic vessels were restricted to the peri-pancreatic mesenchyme until later in development (W14.5-W17), and some of these invading lymphatic vessels contained smooth muscle cells at W17. Interestingly, between W11-W22, most large caliber lymphatic vessels were lined with a characteristic, discontinuous, collagen type IV-rich basement membrane. Whilst lymphatic vessels did not directly intrude the islets of Langerhans, three-dimensional reconstruction revealed that they were present in the vicinity of islets of Langerhans between W17-W22. Conclusion: Our data suggest that the blood and lymphatic machinery in the human pancreas is in place to support endocrine function from W17-W22 onwards. Our study provides the first systematic assessment of the progression of lymphangiogenesis during human pancreatic development

Atoll research bulletin.

no.531-542 (2005

Pathways to clinical CLARITY: volumetric analysis of irregular, soft, and heterogeneous tissues in development and disease

AbstractThree-dimensional tissue-structural relationships are not well captured by typical thin-section histology, posing challenges for the study of tissue physiology and pathology. Moreover, while recent progress has been made with intact methods for clearing, labeling, and imaging whole organs such as the mature brain, these approaches are generally unsuitable for soft, irregular, and heterogeneous tissues that account for the vast majority of clinical samples and biopsies. Here we develop a biphasic hydrogel methodology, which along with automated analysis, provides for high-throughput quantitative volumetric interrogation of spatially-irregular and friable tissue structures. We validate and apply this approach in the examination of a variety of developing and diseased tissues, with specific focus on the dynamics of normal and pathological pancreatic innervation and development, including in clinical samples. Quantitative advantages of the intact-tissue approach were demonstrated compared to conventional thin-section histology, pointing to broad applications in both research and clinical settings.</jats:p

Marked mitigation of transplant vascular sclerosis in FasL(gld) (CD95L) mutant recipients. I. The role of alloantibodies in the development of chronic rejection

Background. In the acute rejection of allografts, the interaction between Fas (CD95) and its ligand (FasL; CD95L) has been shown to be involved in mediating apoptotic cell death. The role, however, of these molecules in the pathogenesis of transplant vascular sclerosis is as yet undetermined. The present study was therefore designed to address this issue. Material. C3H/HEJ FasL(gld) (FasL-; H2(k)) spontaneously mutant mice were used either as donors or recipients of aortic allografts; wild-type C57BI/6 (B6; H2b) were used as corresponding recipients or donors (n=6/group), respectively. Controls included aortas transplanted across appropriate allogeneic and syngeneic strain combinations. For histopathological evaluations, the grafts were harvested at day 40 after transplantation, at which time, splenocytes and sera were also obtained for mixed leukocyte reaction and complement- mediated microcytotoxicity assays, respectively. Results. Similar to aortas obtained from allogeneic controls, allografts harvested from FasL-→B6 recipients had morphological evidence of chronic rejection characterized by circumferential intimal thickening with partial disruption of the elastic membranes. Correspondingly, heightened antidonor cellular reactivity was also witnessed in these recipients. On the contrary, B6 allografts harvested from the majority of C3H→FasL- recipients exhibited marked preservation of aortic morphology. Although these recipients had diminished antidonor cellular proliferation, the titers of alloantibodies were markedly elevated. Conclusion. The presence of FasL-expressing functional cytotoxic T cells is required for the pathogenesis of transplant vascular sclerosis. The significant reduction and/or absence of chronic rejection with the concomitant retention of antidonor humoral response in C3H FasL- recipients of B6 aortas prompt us to suggest that perhaps posttransplantation vasculopathy is initiated by cell-mediated cytotoxicity with its perpetuation facilitated by alloantibodies