Changes in lipid and carnitine concentrations following repeated fasting-refeeding in mice

The purpose of this study was to evaluate the effects of repeated fasting and refeeding on lipid metabolism. Thirty male ICR mice, aged 6 weeks, were fed an AIN-93 control diet during the experimental period. The mice were divided into 5 groups: Non fasting group (ad libitum-fed, NF), fasting for 3 days (F), fasting for 3 days and then refeeding for 4 days repeated once (FRF1), fasting for 3 days and then refeeding for 4 days repeated twice (FRF2), and fasting for 3 days and then refeeding for 4 days repeated three times (FRF3). Rates of body weight gain, epididymal fat weight, and serum TG were significantly decreased in the F, FRF1, FRF2, and FRF3 groups, compared to the NF group. LDL-cholesterol was significantly higher in the FRF3 group than the NF and F groups, but HDL-cholesterol and HDL/TC were significantly lower in the FRF3 group than in the NF and F groups. Serum total carnitine was significantly lower in the FRF1, FRF2, FRF3 groups than the NF and F groups. However, rates of serum and hepatic acyl-carnitine concentration were significantly lower in FRF1, FRF2, and FRF3 than in NF and F. Repeated fasting-refeeding resulted in visible reductions of body weight and fat mass, but it caused ill-effects with lipid and carnitine metabolism in the body

Steroid hormones interrelationships in the metabolic syndrome: an introduction to the ponderostat hypothesis

Sexual dimorphism in the metabolic syndrome. The clairvoyant early implication of sex hormones in the characterization of the metabolic syndrome (MS) was detected early, and in accordance with the well-known sex-related main patterns of fat deposition in obesity: gynoid and android. The differences point to a direct implication of androgens and estrogens in the development, properties and maintenance of obesity and, by extension, to the cumulus of diseases grouped in the MS. For a long time, the key issue of the MS, i.e. the metabolic event explaining (and justifying) most of the derangements of the MS, has been considered to be insulin resistance (...

Chitosan Decontamination with Non-Thermal Nitrogen Plasma to Enable Internal Use

Chitosan (CS) is a ubiquitous biopolymer and is recognized as a promising biomedical material. Potential medical applications for chitosan are extensive and many have shown impressive results. However, chitosan is clinically only used as a topical hemostatic agent due to an inability to sterilize and depyrogenate chitosan without negatively altering its physical and biological properties with conventional techniques. We hypothesized that non-thermal nitrogen plasma (NtNP) would sterilize and depyrogenate chitosan while preserving its biological properties. Since plasma is a surface treatment, we micronized chitosan using cryo-ball and cryo-jet milling to increase its surface to volume ratio. Cryo-jet milling produced the smallest mean particle size (16.05 μm) and reduced molecular weight 36.5% (MW) and degree of deacetylation (DD) 9.6%. NtNP treatment of the resultant chitosan powder produced a sterile chitosan with endotoxin levels \u3c2.50 EU/g, but further reduced MW 40% and DD 6.3%. Nitrogen content and bioadhesivity were unaltered. We tested biologic functionality in a murine orthotopic bladder cancer model in which a previous study showed chitosan dramatically enhanced anti-tumor properties of interleukin-12 (IL-12). We found that bladder tumors regressed – and mice survived to 90 days – in 88% (n=16) and 92% (n=12) of C57Bl/6 mice treated with unsterile chitosan+IL-12 and plasma-sterilized chitosan+IL-12, respectively, but only 8% (n=12) and 0% (n=3) of mice treated with saline and CS-alone, respectively. All plasma-sterilized chitosan+IL-12 (n=11) and 92% of unsterile chitosan+IL-12 (n=13) treated mice rejected tumors upon re-challenge. These results are equivalent to the previously published chitosan+IL-12 study suggesting NtNP sterilization preserved the biological properties of chitosan. A rat model showed that hemostatic chitosan pads sterilized with electron beam irradiation and NtNP stopped femoral artery and artery/vein bleeding better than pads treated with either treatment alone and equivalent to unsterilized pads. A porcine kidney bleeding model showed that NtNP-sterilized pads had superior hemostatic properties compared to e-beam sterilized pads. No complications associated with implanting the pads were observed 14-weeks post-operatively. Histologic examination demonstrated tissue and inflammatory reactions characteristic of foreign body implants. Knowledge gained in these studies will allow clinical testing of parenteral applications of chitosan, including immediate trials of chitosan+IL-12 in bladder cancer patients

Factors affecting energy expenditure and the efficiency of fuel utilization : feeding and exercise models

The first aim of this dissertation was to monitor both rat and human responses to short-term perturbations in energy balance brought about through food energy restriction and refeeding, exercise training and the cessation of exercise training or surgical lipectomy. The second aim of this dissertation was to identify factors which might explain differences in food energy intake in weight-matched, weight-stable "large and small eaters". The final aim of this dissertation was to identify factors which might explain differences in resting energy expenditure in a large sample of weight-stable men and women, including exercising and non-exercising persons, and including persons who may be regarded as "restrained eaters"

Implication du retrait de l'action estrogénique dans le développement de la stéatose hépatique non-alcoolique

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

Glucose Tolerance

The progression from normal glucose tolerance (NGT) to type 2 diabetes involves intermediate stages of impaired fasting glucose (IFG) and impaired glucose tolerance (IGT), also known as prediabetes. The pathophysiology underlying the development of these glucose metabolic alterations is multifactorial, leading to an alteration in the balance between insulin sensitivity and insulin secretion. Our knowledge of the molecular basis of the signaling pathways mediating the various physiologic effects of insulin is steadily advancing. New substrates and signaling molecules have been identified and potential mechanisms involved in the pathophysiology of type 2 diabetes have been revealed. This book summarises the current state of knowledge on the pathophysiology underlying the progression from normal glucose tolerance to type 2 diabetes and therapeutic advances in the improvement of glycaemic control in prediabetic and diabetic states

Host Inflammatory Responses to Adenovirus Respiratory Infection.

Adenoviruses are common causes of acute respiratory infection and myocarditis. It is unclear if manifestations of adenovirus disease are mediated by virus-induced tissue damage or the host immune response to the virus. The main focus of this dissertation was to identify host factors that regulate inflammatory responses and contribute to pathogenesis of acute adenovirus respiratory infection. Due to the species-specificity of adenoviruses, which precludes animal studies with a human adenovirus, I used mouse adenovirus type 1 (MAV-1) to study the pathogenesis of an adenovirus in its natural host. PGE2 is a lipid mediator that promotes expression of a variety of cytokines during acute MAV-1 infection but is not essential for pulmonary immunity to MAV-1. IL-17, a cytokine that is induced during MAV-1 infection and can be upregulated by PGE2, is likewise not essential for control of virus infection or for virus-induced pulmonary inflammation. Exaggerated PGE2 production in hematopoietic stem cell transplantation has been linked to increased susceptibility to infections. Bone marrow transplant (BMT) mice display exaggerated PGE2 production and delayed MAV-1 clearance from the lungs. BMT-induced T cell dysfunction likely contributes to impaired virus clearance but is independent of PGE2 overproduction. Adenoviruses are also important causes of myocarditis. I used MAV-1 to establish a model of adenovirus myocarditis in neonatal mice. IFN-gamma is a proinflammatory mediator during MAV-1 myocarditis, and MAV-1 persistence contributes to ongoing cardiac dysfunction. IFN-gamma is important for induction of the immunoproteasome, a specialized type of proteasome that regulates inflammatory responses, following MAV-1 infection. Inhibition of the constitutive proteasome or the immunoproteasome impairs induction of some proinflammatory cytokines during MAV-1 myocarditis. We have gained insight into contributions of various host factors to MAV-1 acute disease and persistence that may aid the development of alternatives to antiviral drugs for treatment of patients with adenovirus infection. Suppressing some host responses during acute infection may be useful to prevent excess inflammation without affecting antiviral immunity. In immunocompromised hosts, interventions to restore anti-adenoviral immunity could prevent disease associated with excess viral replication. Finally, approaches to prevent or clear adenovirus persistence may lessen the impact of adenovirus-associated chronic disease.PHDMicrobiology and ImmunologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/110390/1/mkmccar_1.pd

Cuantificación y monitorización del hígado graso no alcohólico mediante resonancia magnética

133 p. + anexosIntroducción:La prevalencia de la enfermedad por hígado graso no alcohólico (NAFLD, non-alcoholic fatty liver disease) está aumentando en los países desarrollados en asociación con obesidad y síndrome metabólico. Nuevas técnicas diagnósticas incruentas son necesarias para determinar de forma precisa el contenido hepático de lípidos. Hipótesis de trabajo:En este proyecto de investigación quisimos esclarecer la capacidad diagnóstica de la resonancia magnética (RM) multieco para cuantificar la grasa hepática respecto al método bioquímico de Folch en una biopsia hepática y monitorizar la evolución de la esteatosis en pacientes pertenecientes a un grupo de riesgo de NAFLD (obesidad). Material y métodos:Diseñamos un estudio transversal descriptivo de prueba diagnóstica para la cuantificación de la grasa intrahepática comparando la fracción grasa calculada por RM multieco, el grado histológico de esteatosis y la medición bioquímica de la concentración hepática de triglicéridos (gold standard) en pacientes con criterios de obesidad mórbida y pacientes control no obesos, validando posteriormente los resultados obtenidos en una nueva cohorte con características clínicas similares. Además, se realizó un estudio prospectivo para la monitorización de la esteatosis hepática mediante una nueva RM multieco realizada un año después de cirugía bariátrica/hepática en el grupo de pacientes obesos. Resultados:Nuestros datos indican que la fracción grasa calculada por RM multieco se correlaciona muy positivamente con la medición bioquímica de la grasa hepática, resultando una ecuación que nos permite calcular el valor Folch (bioquímico) estimado conociendo únicamente la fracción grasa por RM. Hemos comprobado que los pacientes obesos sometidos a cirugía bariátrica presentan, al año de la intervención, una mejoría de la esteatosis hepática medida por RM multieco y por el valor Folch estimado. Conclusiones:Todos estos datos indican que la RM multieco puede ser un método diagnóstico incruento que permita cuantificar y monitorizar de forma precisa la grasa intrahepática.133 p.

Extracellular Vesicles and Nanoerythrosomes : The Hidden Pearls of Blood Products

Extracellular vesicles (EV) are nanosized lipid bilayered particles produced by all cells. Due to their remarkable capacity to transport molecular cargo, EVs are considered important mediators of intercellular signalling, making EVs major contributors to cellular functions in health and disease. Recent technological development has improved the analytical techniques of assessment of EV composition and functionality, which has resulted in the interest to apply EVs to diagnostics and therapeutics. Currently, one notable shortcoming of EV studies is the lack of standardisation and comparability of analytical methods. To provide more EV-like alternative for currently used synthetic reference materials that do not resemble EVs, biological reference material was produced from disrupted red blood cells. The produced particles, nanoerythrosomes, were shown to be in many aspects similar to red blood cell EVs but with an additional advantage of mass producibility, nanoerythrosomes are a compelling option for widely distributed reference material enabling improved comparability of EV studies. The second part of the research examined the EVs of platelet concentrate as a potential blood product quality markers and a factor influencing platelet concentrate functionality. In the present study, the EV count of platelet concentrates was shown to be exploitable as a sensitive marker for platelet activation, when compared to other activation markers. Further, platelet-derived EVs in platelet concentrates were shown to contain molecular attributes critical for lipid signalling, e.g., specific phospholipid profile, enzymes important for lipid signalling, and bioactive lipid mediators. Taken together, the results of this thesis show that blood products are a source for nanoerythrosomes with noteworthy potential to improve the comparability of EV studies and, on the other hand, EVs that help to understand the blood product functionality better.Solunulkoiset vesikkelit (extracellular vesicles, EV:t) ovat lipidikaksoiskalvollisia nanopartikkeleita, joita nykykäsityksen mukaan kaikki solut tuottavat. EV:iden avulla solut voivat välittää monipuolista molekyylilastia solujen viestiessä eri fysiologisissa ja patologisissa tehtävissä. Vasta viimeaikainen menetelmä- ja laitekehitys on mahdollistanut EV-molekyylisisällön ja toiminnallisuuden tutkimisen, mikä on herättänyt kiinnostuksen hyödyntää EV:itä diagnostiikassa, terapeuttisina tuotteina ja lääkekuljetuksessa. Vaikka kiinnostus EV:iden mahdollisuuksiin näkyy mm. tutkimusjulkaisujen rajuna kasvuna, on tutkimuskenttä vasta kehittymässä ja mm. toimintamekanismeiltaan poikkeavilla analyysimenetelmillä saatujen tulosten vertailu vaikeaa. Yleisesti käytetyt vertailumateriaalit mahdollistaisivat EV-tutkimuksen vertailtavuuden ja avoimuuden lisääntymisen, mutta nykyiset synteettiset vertailumateriaalit poikkeavat ominaisuuksiltaan huomattavasti biologisista EV:istä, minkä takia väitöskirjatutkimuksen yhtenä tavoitteena oli valmistaa biologinen vertailumateriaali EV-tutkimukseen. Punasoluista tuotettiin nanoerytrosomeja, jotka osoitettiin monilta ominaisuuksiltaan samankaltaisiksi luonnollisesti muodostuvien EV:iden kanssa. Tuotantomenetelmä ja lähtömateriaali ovat kasvatettavissa teollisen massatuotannon kokoluokkaan, mikä tekee nanoerytrosomeista houkuttelevan vaihtoehdon EV-vertailumateriaaliksi. Väitöskirjatutkimuksen toisessa osassa tutkittiin verihiutalevalmisteiden EV:itä ja niiden käyttömahdollisuuksia verihiutalevalmisteiden laadun ja käytön optimoinnissa. EV-määrän mittaaminen todettiin herkäksi menetelmäksi tutkittaessa verihiutaleiden aktivoitumisastetta ja verrannolliseksi kahden käytössä olevan aktivaatioparametrin kanssa. Lisäksi verihiutalevalmisteiden EV:iden osoitettiin sisältävän erityisen fosfolipidiprofiilin ja fosfolipideistä saatavien rasvahappojen muokkaamiseen tarvittavien entsyymien lisäksi bioaktiivisia lipidimediaattoreita, joten EV:iden voidaan ajatella osallistuvan solujen väliseen viestintään esim. lipidimediaattoreiden välityksellä. Väitöskirjan tulokset osoittavat, että verivalmisteista voidaan tuottaa nanoerytrosomeja joita voidaan hyödyntää vertailumateriaaleina EV-tutkimuksessa tai eristää EV:itä hyödynnettäväksi merkkiaineina arvioitaessa verivalmisteen kuntoa ja toiminnallisia vaikutuksia