Lineage tracing and resulting phenotype of haemopoietic-derived cells in the pancreas during beta cell regeneration

Aims Transplantation of bone marrow-derived haemopoietic stem cells following streptozotocin (STZ) treatment to induce pancreatic beta cell loss in mice causes the partial regeneration of beta cell mass, with many haemopoietic cells demonstrating endothelial cell markers. This study used genetically tagged haemopoietic lineage-derived cells to determine how endogenous cells are mobilised following beta cell loss and subsequent replacement. Methods A double transgenic mouse model, Vav-iCre; R26R-enhanced yellow fluorescent protein (YFP), was used where only haemopoietic lineage cells expressed the Vavl gene promoter allowing expression of the YFP reporter gene. Between postnatal days 2 and 4 mice were injected with STZ or vehicle (control) and body weight and glycaemia were monitored. Mice were killed between days 10 and 130, and the pancreases were examined by immunofluorescence microscopy. Results YFP-expressing cells infiltrated the pancreas at all ages, being present around newly forming islets at the pancreatic ducts, and within larger islets. Small numbers of YFP-positive cells (\u3c5%) co-stained for the macrophage markers F4/80 or Mac1, for cytokeratin 19, or for the transcription factor pancreatic and duodenal homeobox 1 (PDX-1), but no co-localisation was seen with insulin or other endocrine hormones. Within islets approximately 30% of YFP-positive cells co-stained for the endothelial cell marker CD31, and following STZ the number of haemopoietic-derived cells, and the proportion that were CD31-positive, both significantly increased after 21 and 40 days, coincident with a partial replacement of beta cells. Conclusions Our results suggest that following beta cell loss endogenous haemopoietic-lineage cells contribute to intra-islet angiogenesis, which supports a partial recovery of beta cell mass. © Springer-Verlag 2010

A Novel Hybrid Imaging System to Aid in Surgical Decision Making

Background: Breast cancer accounts for 25% of all cancer cases among women. In breast-conserving surgery, a common treatment, the tumour is excised with a healthy tissue margin. However, detection of the margin can be difficult. Current techniques to guide excision are often insufficient, and re-excision can occur up to 25% of the time. Methods: Photoacoustic imaging is a hybrid imaging modality that combines the advantages of optical imaging and ultrasound while using safe non-ionizing light. This project involves the development of a novel imaging system with a new scanner design to overcome common limitations and provide images to aid in surgical decision making. Results: A new imaging system has been developed and tested with imaging phantoms. Discussion & Conclusion: Results obtained with imaging phantoms are promising; high resolution images with good contrast have been shown. Further research using surgical excised tumour specimens will be conducted as a pilot study. Interdisciplinary Reflection: Various imaging methods are combined and applied to medical needs. In addition, this imaging system is incredibly versatile and can be used for many areas of research including animal studies, human studies, and from macroscopic imaging to microscopy

Potential for photoacoustic imaging of the neonatal brain

Photoacoustic imaging (PAI) has been proposed as a non-invasive technique for imaging neonatal brain injury. Since PAI combines many of the merits of both optical and ultrasound imaging, images with high contrast, high resolution, and a greater penetration depth can be obtained when compared to more traditional optical methods. However, due to the strong attenuation and reflection of photoacoustic pressure waves at the skull bone, PAI of the brain is much more challenging than traditional methods (e.g. near infrared spectroscopy) for optical interrogation of the neonatal brain. To evaluate the potential limits the skull places on 3D PAI of the neonatal brain, we constructed a neonatal skull phantom (1.4-mm thick) with a mixture of epoxy and titanium dioxide powder that provided acoustic insertion loss (1-5MHz) similar to human infant skull bone. The phantom was molded into a realistic infant skull shape by means of a CNCmachined mold that was based upon a 3D CAD model. To evaluate the effect of the skull bone on PAI, a photoacoustic point source was raster scanned within the phantom brain cavity to capture the imaging operator of the 3D PAI system (128 ultrasound transducers in a hemispherical arrangement) with and without the intervening skull phantom. The resultant imaging operators were compared to determine the effect of the skull layer on the PA signals in terms of amplitude loss and time delay. © 2013 Copyright SPIE

Direct comparison of the abilities of bone marrow mesenchymal versus hematopoietic stem cells to reverse hyperglycemia in diabetic NOD.SCID mice

Both bone marrow-derived hematopoietic stem cells (HSC) and mesenchymal stem cells (MSC) improve glycemic control in diabetic mice, but their kinetics and associated changes in pancreatic morphology have not been directly compared. Our goal was to examine the time course of improvements in glucose tolerance and associated changes in β-cell mass and proliferation following transplantation of equivalent numbers of HSC or MSC from the same bone marrow into diabetic non-obese diabetic severe combined immune deficiency (NOD.SCID) mice. We used transgenic mice with a targeted expression of yellow fluorescent protein (YFP) driven by the Vav1 gene promoter to genetically tag HSC and progeny. HSC were separated from bone marrow by fluorescence-activated cell sorting and MSC following cell culture. Equivalent numbers of isolated HSC or MSC were transplanted directly into the pancreas of NOD.SCID mice previously made diabetic with streptozotocin. Glucose tolerance, serum insulin, β-cell mass and β-cell proliferation were examined up to 28 days following transplant. Transplantation with MSC improved glucose tolerance within 7 days and serum insulin levels increased, but with no increase in β-cell mass. Mice transplanted with HSC showed improved glucose tolerance only after 3 weeks associated with increased β-cell proliferation and mass. We conclude that single injections of either MSC or HSC transiently improved glycemic control in diabetic NOD.SCID mice, but with different time courses. However, only HSC infiltrated the islets and were associated with an expanded β-cell mass. This suggests that MSC and HSC have differing mechanisms of action

Susceptibility to fatty acid-induced β-cell dysfunction is enhanced in prediabetic diabetes-prone biobreeding rats: A potential link between β-cell lipotoxicity and islet inflammation

β-Cell lipotoxicity is thought to play an important role in the development of type 2 diabetes. However, no study has examined its role in type 1 diabetes, which could be clinically relevant for slow-onset type 1 diabetes. Reports of enhanced cytokine toxicity in fat-laden islets are consistent with the hypothesis that lipid and cytokine toxicity maybe synergistic. Thus, β-cell lipotoxicity could be enhanced in models of autoimmune diabetes. To determine this, we examined the effects of prolonged free fatty acids elevation on β-cell secretory function in the prediabetic diabetes-prone BioBreeding (dp-BB) rat, its diabetes-resistant BioBreeding (dr-BB) control, and normal Wistar-Furth (WF) rats. Rats received a 48-h iv infusion of saline or Intralipid plus heparin (IH) (to elevate free fatty acid levels ∼2-fold) followed by hyperglycemic clamp or islet secretion studies ex vivo. IH significantly decreased β-cell function, assessed both by the disposition index (insulin secretion corrected for IH-induced insulin resistance) and in isolated islets, in dp-BB, but not in dr-BB or WF, rats, and the effect of IH was inhibited by the antioxidant N-acetylcysteine. Furthermore, IH significantly increased islet cytokine mRNA and plasma cytokine levels (monocyte chemoattractant protein-1 and IL-10) in dp-BB, but not in dr-BB or WF, rats. All dp-BB rats had mononuclear infiltration of islets, which was absent in dr-BB and WF rats. In conclusion, the presence of insulitis was permissive for IH-induced β-cell dysfunction in the BB rat, which suggests a link between β-cell lipotoxicity and islet inflammation. Copyright © 2013 by The Endocrine Society

Effects of Protein Deficiency on Perinatal and Postnatal Health Outcomes

There are a variety of environmental insults that can occur during pregnancy which cause low birth weight and poor fetal health outcomes. One such insult is maternal malnutrition, which can be further narrowed down to a low protein diet during gestation. Studies show that perinatal protein deficiencies can impair proper organ growth and development, leading to long-term metabolic dysfunction. Understanding the molecular mechanisms that underlie how this deficiency leads to adverse developmental outcomes is essential for establishing better therapeuticstrategies that may alleviate or prevent diseases in later life. This chapter reviews how perinatal protein restriction in humans and animals leads to metabolic disease, and it identifies the mechanisms that have been elucidated, to date. These include alterations in transcriptional and epigenetic mechanisms, as well as indirect means such as endoplasmic reticulum (ER) stress and oxidative stress. Furthermore, nutritional and pharmaceutical interventions are highlighted to illustrate that the plasticity of the underdeveloped organs during perinatal life can be exploited to prevent onset of long-term metabolic disease

Maternal Undernutrition and Long-term Effects on Hepatic Function

Undernutrition in utero, regardless of the source, can impair proper liver development leading to long-term metabolic dysfunction. Understanding the molecular mechanisms underlying how nutritional deficits during perinatal life lead to permanent alterations in hepatic gene expression will provide better therapeutic strategies to alleviate the undernourished liver in postnatal life. This chapter addresses the different experimental models of undernutrition in utero, and highlights the direct and indirect mechanisms involved leading to metabolic diseases in the liver. These include hypoxia, oxidative stress, epigenetic alterations, and endoplasmic reticulum (ER) stress. In addition, promising perinatal nutritional and pharmaceutical interventions are highlighted which illustrate how the placidity of the developing liver can be exploited to prevent the onset of long-term metabolic disease

Desarrollo y control de un tumor experimental de ovario

El objetivo de esta tesis fue el estudio de un modelo animal de tumor ovárico con ciertas similitudes con patologías ováricas hormono-dependientes y endocrinamente funcionales. El luteoma se desarrolla al autoinjertar un ovario en el bazo de una rata hembra adulta bilateralmente ovariectomizada, por la hipergonadotrofinemia resultante. En estudios de un año de duración determinamos que son tumores benignos y no modifican el estado general del animal. La mayoria de los animales portadores de tumor cursan con gonadotrofinas elevadas por un período de tiempo prolongado. Los luteomas secretan inhibina determinando un patrón particular de secreción de FSH. In vitro estos tumores presentan la esteroidogénesis basal alterada. La administración crónica de buserelina (análogo de GnRH)tuvo un claro efecto antitumoral: redujo la aparición de tumores e inhibió su crecimiento. A través de receptores específicos de afinidad similar al ovario control, la buserelina ejerce un efecto directo sobre las células de luteomas: inhibe la secreción de progesterona estimulada por LH. Las células tumorales son más sensibles a este efecto que las células lúteas control. Sin embargo, los receptores para GnRH en las células de los luteomas se encuentran desacoplados de su via clasica de segundos mensajeros: fosfolipasa C. En nuestros trabajos caracterizamos los luteomas en diversos aspectos que abarcan al animal entero hasta estudios subcelulares.The aim of the present thesis was the study of an animal model of ovarian tumor. The interest of this tumor lies in its similarities with ovarian pathologies which are hormone-dependent and endocrinologically active. This luteoma develops when an ovary is grafted into the spleen of a bilaterally ovariectomized adult female rat, as a consequence of the resulting hipergonadotrophinemia. In a year-long study we determined that these tumors are benign and do not alter the general condition of the animals. The majority of the tumor-bearing animals display high gonadotrophin levels for long periods of time. Luteoma secrete inhibins, which determine the particular FSH secretion pattern. In vitro these tumors show basal steroidogenesis alterations. Chronic buserelin (a GnRH analog) administration had a clear antitumoral effect: it inhibited initial tumor development and induced a reduction in tumor volume. Buserelin, acting on specific receptors with affinity similar to that in control ovaries, has a direct effect on luteoma cells: it inhibits LH-stimulated progesterone secretion. Tumoral cells are more sensitive to this effect than control luteal cells. However, GnRH receptors in luteoma cells are uncoupled from their classic second messenger generating system: phospholipase C. In our work we have characterized these luteoma in a variety of aspects including the whole animal and subcellular studies.Fil:Chamson, Astrid de Reig. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Spatiotemporally-induced over expression of NKx2.2 in pancreatic tissue

104 p. : ill. ; 22 cm. 2nd printing.https://digitalcommons.pittstate.edu/ertman/1093/thumbnail.jp