Osteopetrosis is a metabolic bone disease in mammals characterized by a generalized skeletal sclerosis caused by reduced bone resorption. This reduced bone resorption is manifested in afflicted animals by abnormal bone shape, reduced or absent marrow cavities, extramedullary hemopoiesis, abnormal mineral homeostasis and absent or delayed tooth eruption. The available osteopetrotic animal mutations have been a constant source of fruitful investigations concerning the systemic regulation of osteoclastogenesis and bone metabolism. Tooth eruption, on the other hand, is a localized manifestation of the timely activation of bone resorption and bone formation on opposite sides of an erupting tooth. Its rate-limiting step is the speed of bone resorption to form the eruption pathway. In this dissertation, we used two osteopetrotic rat mutations, toothless (tl) and microphthalmia blanc (mib), to investigate the abnormal development of osteoclasts and tooth eruption in mutant rats with an emphasis on the role of systemic and local factors. The significant contributions to this work are listed below. 1. In the toothless rat, a mutation lacking erupted dentition due to severely reduced bone resorption, colony-stimulating factor-1 (CSF-1) promoted tooth eruption but this was delayed compared to normal rats. Eruption was accompanied by changes in the populations of tartrate-resistant acid phosphatase-positive (TRAP+) mononuclear cells in the dental follicle and TRAP+ osteoclasts on adjacent alveolar bone surfaces. These cell populations were dramatically increased in treated mutants compared to untreated tl rats, but the timing of their appearance was delayed compared to normal littermates. This lag in the appearance of osteoclasts and their precursors corresponded to the delay in eruption of first molars in treated tl rats. 2. CSF-1 also accelerated the eruption of molars in normal rats. CSF-1 increased the number of TRAP+ mononuclear cells in the dental follicle and TRAP+ osteoclasts on adjacent alveolar bone surfaces, but had no effect on the timing of their appearance in normal rats. 3. Our data revealed a differential effect on tooth eruption of the growth factors CSF-1 and epidermal growth factor (EGF). CSF-1 accelerated eruption of molars in normal rats, but had no effect on incisor eruption. On the other hand, EGF accelerated incisor eruption; but did not affect molar eruption in normal rats. 4. We have described the mechanism for the transient, mild form of osteopetrosis inherited by mib rats. Mutant animals possess a typical sclerosis at birth, which diminished--but was not resolved--during the first postnatal month. These characteristics are caused by early reductions in osteoclast number and function which improve to normal levels by 4 weeks. Osteoclast numbers were severely reduced in mib rats between birth and 2 weeks, but improved to near normal levels by 4 weeks. Neonatal abnormalities in osteoclast function included reduced staining for the functional enzymes TRAP and TrATPase, decreased levels of mRNA for both TrATPase and CAll, and inability to form a well-developed ruffled border. None of these defects were apparent after the first postnatal month. 5. Finally, we have shown that the dental abnormalities caused by the mild, transient form of osteopetrosis in mib rats are limited to incisor defects and delayed eruption of all teeth. Histologic and radiographic examination of mutant incisors revealed that, contrary to the situation in normal rats, the apex of the incisors of mib rats failed to extend past the first molar region to the third molar. The incisor apex of newborn mib rats was misshaped due to ankylosis of incisor matrices with alveolar bone. This ankylosis was temporary, being resolved by the third postnatal day. The delayed eruption of incisors in mib rats and abnormal shape and occlusion of these teeth in older animals is a consequence of the temporary ankylosis in newborn rats.

Pneumatosis intestinalis, air within the bowel wall, continues to have an elusive etiology due to its varied clinical presentation and associated disease processes. Pneumatosis may be an incidental finding on a routine CT Scan or it could present as peritonitis with intra-abdominal free air. The pathogenesis, therefore, is likely to be multifactorial rather than directly related to one particular, inciting pathology. Here we present a case of a 73-year-old male scheduled for a non-emergent incisional hernia repair who was found to have peritoneal free air without physical exam findings of peritonitis. This unusual case illustrates a rare presentation of small bowel, omental, and abdominal wall pneumatosis. The objective of this presentation is to broaden the clinician’s understanding of pneumatosis intestinalis, including a recommendation to discern the underlying illness as emergent or benign. Finally, we make the case for clinical intuition and the physical exam.

The pancreas is located below the liver and adjacent to the small intestine where it connects to the duodenum. It consists of exocrine and endocrine components. The exocrine portion makes enzymes which are deposited in the duodenum to digest fats, proteins, and carbohydrates. Exocrine tissue also makes bicarbonates that neutralize stomach acids. The endocrine portion produces hormones such as insulin and glucagon which are released into the blood stream. These hormones regulate glucose transport into the body's cells and are crucial for energy production. The pancreas is associated with diseases such as cancer, diabetes, Annular pancreas and Nesidioblastosis. Annular pancreas and Nesidioblastosis are congenital malformations associated with excess endocrine tissue of the pancreas and its structures. Understanding the development of the pancreas might lead to insight of these diseases. The pancreas arises from the endoderm. In zebrafish, Nodal signaling activates mix-type and gata genes that then function together to regulate sox32 expression which is necessary and sufficient to induce endoderm formation. Interestingly, sox32 is exclusive to zebrafish and works synergistically with pou5f1 to regulate its own expression and turn on sox17 expression. sox17is evolutionarily conserved from zebrafish to mouse and is necessary for endoderm formation. Signals from within the endoderm and the surrounding mesoderm specify regions in the endoderm to develop into the pancreas and other endodermal organs. Sonic hedgehog (shh) expression in the foregut establishes the anterior boundary of the pancreas primordium while cdx4 expression establishes the posterior boundary, but what regulates these factors is unclear. We determined that two Three Amino Acid Loop Extension (TALE) homeodomain transcription cofactors, Meis3 and Pbx4, regulate shh expression in the anterior endoderm. Disrupting either meis3 or pbx4 reduces shh expression in the anterior endoderm. As a result, anterior ectopic insulin expression occurs outside the normal pancreatic domain. Therefore, we discovered upstream regulatory factors of shhexpression in the anterior endoderm, which is necessary for patterning the endoderm and pancreas primordium. We performed an ENU (N-ethyl-N-nitrosurea) haploid screen to look for endocrine pancreas mutants and to find other factors involved in pancreas development and patterning. From the screen, we characterized two mutants. We identified an aldh1a2 mutant, aldh1a2um22, which blocks the production of Retinoic Acid (RA) from vitamin A. While RA is known to be necessary for differentiation of the pancreas and liver, we also found it to be necessary for intestine differentiation. Two other aldh family genes exist in the zebrafish genome, but our data suggests that aldh1a2is the only Aldh that functions in endoderm differentiation and it is maternally deposited. From the screen, we discovered a second mutant, 835.4, that spontaneously arose within the background. pou5f1 expression is normal in mutant embryos, but sox32 expression is reduced and sox17 expression is lost. Downstream endoderm genes of sox17 are also lost and as a result no endodermal organs develop. Rescue experiments indicate that the mutation is located between sox32 and sox17 in the endoderm pathway. We currently have not been successful at mapping this mutation and therefore are unable to rule out the possibility that it lies in the sox17 gene. However, our data suggest that the mutation occurs in a new gene that is necessary for sox17 expression, potentially working with sox32 and/or pou5f1.

Adipose tissue inflammation has an impact on liver health and it has been demonstrated that chronic alcohol consumption leads to the expression of pro-inflammatory markers in the adipose tissue. A thorough characterization of alcohol-induced adipose inflammation is lacking, and is important to understand in order to identify immune-related mechanisms that drive this phenomenon. Current therapeutic regimens for alcoholic liver disease are ineffective. It is critical to understand how other organs influence liver injury in this disease when developing novel and effective therapies in the future. Alcoholic liver disease exhibits a sexual dimorphism; women are more susceptible to liver injury than men and the same paradigm exists in rodent models. Here, I demonstrate that female mice have greater alcohol-induced adipose tissue inflammation than male mice, evidenced by greater expression of pro-inflammatory cytokines and cell markers. Further, female mice also exhibit higher expression of toll-like receptor genes in the adipose tissue, suggesting a potential role for the innate immune system in alcohol-induced adipose inflammation. Toll-like receptor 4 (TLR4) has been demonstrated to drive inflammation in both the liver and adipose tissue. I used both germline and conditional knockouts of Tlr4 to characterize alcohol-induced changes in the immune cell composition of adipose tissue. Alcohol increased the number of pro-inflammatory adipose tissue macrophages. This macrophage phenotype switching is partially dependent on TLR4; germline, but not myeloid-specific, Tlr4-deletion prevents macrophage phenotype switching. Overall, my work demonstrates that alcohol-induced adipose tissue inflammation is related to liver injury and that TLR4 contributes to adipose macrophage phenotype switching.

Background To investigate plasma microRNA (miRNA) profiles indicative of hepatotoxicity in the setting of lethal acetaminophen (APAP) toxicity in mice. Methods Using plasma from APAP poisoned mice, either lethally (500 mg/kg) or sublethally (150 mg/kg) dosed, we screened commercially available murine microRNA libraries (SABiosciences, Qiagen Sciences, MD) to evaluate for unique miRNA profiles between these two dosing parameters. Results We distinguished numerous, unique plasma miRNAs both up- and down-regulated in lethally compared to sublethally dosed mice. Of note, many of the greatest up- and down-regulated miRNAs, included, but were not limited to, 574-5p, 466g, 466f-3p, 375, 29c, and 148a. There was a statistically significant increase in alanine aminotransferase levels in the lethal compared to sublethal APAP dosing groups at the 12 h time point ( P < 0.001). There was 90% mortality in the lethally compared to sublethally dosed mice at the 48 h time point ( P = 0.011). Conclusion We identified unique plasma miRNAs both up- and down-regulated in lethally dosed APAP poisoned mice.

Chronic intake of alcohol can result in a range of pathology in the liver. Whilst the earliest changes observed with chronic ethanol, including the accumulation of lipid, or steatosis, are readily reversible upon cessation of alcohol consumption, longer exposure to ethanol may achieve more complex disease states including steatohepatitis, fibrosis, and cirrhosis that can cause irreversible damage and progress to fulminant hepatic failure. A key concept in the pathogenesis of alcoholic liver disease is that chronic ethanol primes the liver to increased injury through an interplay between hepatocytes and non-parenchymal cells, chiefly immune cells, of the liver. These relationships between hepatocytes and non-parenchymal cell types in alcoholic liver disease are reviewed in Chapter 1A. The Hypoxia Inducible Factors are a set of transcription factors that classically have been described as affecting a homeostatic response to conditions of low oxygen tension. Alcoholic liver disease is marked by increased hepatic metabolic demands, and some evidence exists for increased hepatic tissue hypoxia and upregulation of hypoxia-inducible factor mRNA with chronic alcohol. However, the biological significance of these findings is unknown. In Chapter 1B, we review the literature on recent investigations on the role of hypoxia inducible factors in a broad array of liver diseases, seeking to find common themes of biological function. In subsequent chapters, we investigate the hypothesis that a member of the hypoxia inducible- factor family, HIF1α, has a role in the pathogenesis of alcoholic liver disease. In Chapter 2, we establish a mouse model of alcoholic liver disease and report data confirming HIF1α activation with chronic ethanol. We demonstrate that HIF1α protein, mRNA, and DNA binding activity is upregulated in ethanol-fed mice versus pair-fed mice, and that some upregulation of HIF2α protein is observable as well. In Chapter 3, we utilize a mouse model of hepatocyte-specific HIF1α activation and demonstrate that such mice have exacerbated liver injury, including greater triglyceride accumulation than control mice. Using cre-lox technology, we introduce a degradation resistant mutant of HIF1α in hepatocytes, and after four weeks of ethanol feeding, we demonstrate that mice with the HIF1α transgene have increased liver-weight to body weight ratio and higher hepatic triglyceride levels. Additionally, several HIF1α target genes are upregulated. In Chapter 4, we examine the relationship between HIF1α activation and hepatic lipid accumulation using a recently published in vitro system, in which lipid accumulation was observed after treating Huh7 cells with the chemokine Monocyte Chemoattractant Protein-1 (MCP-1). We report that MCP-1 treatment induces HIF1α nuclear protein accumulation, that HIF1α overexpression in Huh7 cells induces lipid accumulation, and finally, that HIF1α siRNA prevents MCP-1 induced lipid accumulation. In Chapter 5, we use mouse models to investigate the hypothesis that suppression of HIF1α in hepatocytes or cells of the myeloid lineage may have differing effects on the pathogenesis of alcoholic liver disease. We find that ethanol-fed mice expressing a hepatocyte-specific HIF1α deletion mutant exhibit less elevation in liver-weight body ratio and diminished hepatic triglycerides versus wild-type mice; furthermore, we find that challenging these mice with lipopolysaccharide (LPS) results in less liver enzyme elevation and inflammatory cytokine secretion than in wild-type mice. In Chapter 6, we offer a final summary of our findings and some directions for future work.

Blood glucose (BG) spikes increase chronic disease risk in those with and without diabetes. The fiber and phytonutrient content of fruit, such as raspberries has the potential to attenuate the BG spike of a high glycemic load (HGL) meal. We examined the effect of red raspberries (RRs) on the BG spike when added to a HGL meal. In this randomized cross-over trial, 16 university students were given breakfast cereal and almond milk (control), the control breakfast with 140g added RRs, and the control breakfast with sugar equivalent to the sugar content of the RRs (50% sugar increase from control). Meals given on 3 separate test days, being separated by a 1-week washout period. BG was measured at: fasting then 15 min, 30 min, 60 min, 90 min, and 120 min postprandial. Repeated measures ANOVA was performed to investigate differences in peak minus baseline BG (spike) and glucose incremental area under the curve (IAUC). The added RR meal had a lower BG spike compared to the added sugar meal (-12.8 mg/dL, CI: -22.8 to -2.79, p = 0.0083). Additionally, a lower BG was seen comparing the added RR meal to the control meal (-10.9 mg/dL, CI: -20.9 to -0.83, p = 0.0318). There were no significant differences for IAUC and the timing of peak BG among the meals. RR effect is likely attributed to high fiber-to-sugar ratio, polyphenol content, and greater amount of beneficial micronutrients. Based on obtained results from this pilot study, the practice of adding RRs to HGL meals such as breakfast, seems to reduce risk for T2DM in health populations through BG spike attenuation.

Clostrioides difficile is a common cause of nosocomial (hospital-acquired) infections. Patients receiving antibiotic treatment experience dysbiosis of gut microbiota, and C. difficile, normally held in check by the various other organisms, takes this opportunity to propagate. Symptoms of infection generally include diarrhea, colitis, dehydration, and fever. Understanding that C. difficile generally only causes illness when it is the dominant bacterium (i.e. when growth is relatively unchecked by other microbes), it is appropriate to investigate potential competitive organisms that may be introduced after antibiotic courses or during active C. difficile infection to effectively displace it. Fecal samples from the University of Central Florida Lift fecal collection station were aseptically plated onto modified cycloserine cefoxitin fructose agar (CCFA). Visually remarkable colonies (certain colonies that looked unique in comparison to others) were restreaked on new plates of the same media to verify growth, then transferred to brain heart infusion-supplemented (BHIS) plates for propagation. Colonies were inoculated in glycerol stocks for storage, then grown in BHIS liquid media to prepare for identification. Genomic extraction was performed on each sample, and spectrophotometric quantification and gel electrophoresis were executed to confirm successful extraction. Genomic samples will be sent to an external laboratory for identification via polymerase chain reaction and Sanger sequencing. We hypothesize that at least one bacterial strain from the fecal collection station will potentially inhibit C. difficile infection. Should such an organism be identified, it follows that the efficacy of its application in conventional hospital settings may be examined. Current regulation of fecal microbiota transplants, an effective therapeutic practice, is cumbersome, and changing the classification of fecal transplants may improve timeliness and effectiveness of treatment.

The regulation of glucagon-like peptide-1 and peptide YY hormone levels are regulated based on different influential factors, but primarily levels are dependent upon ingested food content. As meals today become more fat-enriched, there is greater requirement for evaluation of these hormones that regulate insulin and satiety levels within the body. We have shown that the gene expression transcript production of glucagon-like peptide-1 and peptide YY are modulated by different concentrations, and times of short-chain fatty acids and long-chain fatty acids. Although the peptide hormone levels have the influential physiological role on effector tissue, the regulation of these hormones begins at the transcript levels. Recent research indicates that glucagon-like peptide-1 and peptide YY hormones are altered in response to different free-fatty acids. The present investigation generally demonstrated an overall decrease in both hormones after chronic exposure to fatty acids. Intestinal secretin tumor cell line (STC-1 cells) was used as a representative for intestinal L-cells. Quantitative real-time PCR analysis was used to determine the changes in RNA transcripts. Overall, there was a decrease in the 3-hour timeline, which continued to decrease in the 16-hour and 24-hour timelines for glucagon-like peptide-1. Peptide YY transcript expression in 3-hours increased significantly after exposure to propionate, a significant decrease after exposure to acetate, and no significant increase or decrease after exposure to butyrate. However, there was a significant decrease in peptide YY once reaching 24-hour exposure. It was determined there is a threshold for different concentrations of free-fatty acids to influence glucagon-like peptide-1 and peptide YY production, which was present in the different concentrations of butyrate. Lastly, exposure to both concentrations of linolenic acid caused a significant decrease in glucagon-like peptide-1 and peptide YY.

In response to ingestion of nutrients, enteroendocrine L cells secrete the incretin hormone, glucagon-like peptide-1 (GLP-1), to enhance glucose-dependent insulin release. Therapies related to GLP-1 are approved for type 2 diabetes. The GLP-1 receptor (GLP-1R) is expressed in cells of the gastrointestinal tract and elsewhere. In pancreatic beta cells, GLP-1R are coupled to the Gs/cAMP/PKA pathway. The expression and function of GLP-1R in gastrointestinal smooth muscle are not known. Aim. To test the hypothesis that GLP-1 regulates smooth muscle function by acting on GLP-1R expressed on smooth muscle. Methods. Smooth muscle cells (SMC) were isolated and cultured. Expression of GLP-1R mRNA was measured by RT-PCR. Expression of GLP-1R protein was measured by western blot. The effect of GLP-1 (7-36) amide on Gαs activation, cAMP formation, and PKA activity was examined in cultured SMC. The effect of GLP-1 on basal activity and on acetylcholine-induced contraction was measured in intact colon via organ bath. Results. Amplification of GLP-1R mRNA suggested expression of GLP-1R mRNA in mucosal and non-mucosal colon cells, which was confirmed in pure SMC cultures. Similar patterns of protein expression were obtained with western blot. Addition of GLP-1 caused relaxation of phasic activity and agonist-induced tonic contractions in intact colon, suggesting a role of smooth muscle Gs-coupled GLP-1R in mediating relaxation. In SMC, GLP-1 (7-36) amide activated Gas, increased cAMP levels, and stimulated PKA activity. Conclusion. Colonic SMC express GLP-1R, and GLP-1 inhibits both basal and acetylcholine-induced contraction. The GLP1-R is coupled to the heterotrimeric G protein, Gas.