This investigation examines cell proliferation in the pancreas of the Syrian golden hamster. Three main themes are pursued. First, normal pancreatic growth and development is reviewed. Emphasis is placed on histogenesis and trophic stimuli. Secondly, modulation of pancreatic growth is examined. A new method for producing partial pancreatic duct obstruction using a technique of cellophane wrapping is described. The histologic alterations induced by wrapping are the same as those associated with the early changes of chemical pancreatic carcinogenesis--duct epithelial hyperplasia, metaplasia and nesidioblastosis. Morphometric, immunocytochemical, autoradiographic and G.I. hormone analysis are also utilized to characterize this model. Importantly, experimental nesidioblastosis can result in islets which are functionally capable of reversing streptozocin-induced diabetes. Thirdly, aberrant pancreatic growth was investigated in relation to carcinogenesis. Clinical cancer epidemiology is reviewed with special reference to risk factors and postulated trophic influences. Experimentally, the trophic effects of diet, cholecystectomy and duct obstruction were investigated. Finally a new model for the induction of carcinoma of the head of the pancreas, using cellophane wrapping in association with a chemical carcinogen, is presented.

No description available.

Diabetes has been shown to affect the thickness of the basement membrane in various human tissues and organs. The purpose of this thesis is to determine whether diabetes can cause thickening of the anterior capsule basement membrane (ACBM), and correlate the findings with the duration and the severity of diabetes. For the purpose of this study, anterior lens capsule specimens of diabetic patients (DP), and non-diabetic patients (NDP) are collected from phaco-emulsification cataract surgeries. All cases are formalin-fixed, paraffin-embedded and stained with H&E and periodic acid-Schiff. The ACBM thickness is measured and reviewed under a light microscope. The results of this thesis showed that the mean thickness of ACBM is significantly thicker in DP as compared to NDP. The ACBM thickness is increased with patient age in both DP and NDP. Moreover, in DP the ACBM thickness increased with the duration and the severity of diabetes.

The inflammatory response due to chronic smoking in COPD patients has been well characterized with increases in CD3+ T lymphocytes. A murine model was chosen in our laboratory as a good model of human emphysema. / The first part of my project was to characterize the lung inflammatory response via immunocytochemistry in each mouse strain exposed to chronic smoke inhalation for a six-month period. / Several T lymphocyte subsets (i.e. naive, central memory and effector memory) have been characterized in the immune system both in humans and mice. These subsets have different homing potentials and effector functions, and can be identified with cell surface markers. The second part of my project was to determine these T-cell subset ratios in the lungs of each strain after chronic smoke exposure. / The third part of my project was to assess apoptosis in each strain after smoke exposure.

Uveal melanoma has a high mortality rate, with approximately 45% of patients dying due to liver metastasis within 15 years of initial diagnosis and local treatment. As the eye lacks lymphatics, there is no staging of uveal melanoma according to lymph node metastasis. The search for new prognostic factors and therapeutic targets is therefore crucial to the advancement of uveal melanoma research. The expression of cyclooxygenase-2 (COX-2) has been investigated in human malignancies such as cutaneous melanoma. Immunohistochemical studies were therefore used to show that uveal melanomas do express COX-2 and that this expression is associated with various histopathological markers of poor prognosis. A novel sub-classification of mixed-cell-type tumours was devised, according to COX-2 expression. / The numerous studies of COX-2 expression in human malignancies have focused on COX-2 expression in tumour cells. This work shows COX-2 to be expressed in uveal melanoma tumour cells and tumour-associated macrophages (TAM), with a higher amount of COX-2 expression associated with a higher amount of TAM infiltration. These results may help explain the poor prognosis previously attributed to a high amount of TAM infiltration in uveal melanoma. / This thesis also investigated the co-expression of COX-2, insulin-like growth factor 1 receptor (IGF-IR) and phosphorylated-Akt (p-Akt). A recent paper had shown IGF-1R expression to be associated with a higher risk of uveat melanoma metastasis. IGF-1R expression, present to different degrees in almost all uveal melanoma cases, represents the presence of the receptor, whereas p-Akt expression represents an activated downstream pathway. This thesis showed that p-Akt is expressed in uveal melanoma. While some uveal melanoma cases co-expressed COX-2, IGF-1R and p-Akt, all cases were positive for at least one of the three markers. / Studies in human malignancies, including uveal melanoma, have shown COX-2 inhibitors to have effects on both COX-2 positive and negative tumour cells. The effects of COX-2 inhibitors on IGF-1R and p-Akt have been postulated as possible mechanisms behind these COX-2 independent effects. This work has provided a rationale for the study of COX-2 inhibitors, alone or in combination with IGF-1R inhibitors, as systemic adjuvant treatment of this life-threatening intra-ocular malignancy.

Atopic dermatitis (AD) is a common inflammatory skin disease. Autoimmunity has been suggested to play a role in the pathogenesis of AD. The recently described TH17 cells are reported to be involved in the pathogenesis of some autoimmune diseases. We examined the expression of the TH17-associated cytokines in AD patients and explored the presence of this T cell subset particularly in chronic lesions. AD patients (acute and chronic) were recruited together with a comparable group of normal subjects. Skin biopsy specimens were taken from each. The expression of IL-17A, IL-17F, and IL-22 were studied using immunocytochemistry. Identification of IL-17A/F-producing T lymphocytes was confirmed by immunofluorescence. Using laser capture microdissection (LCM), we isolated mononuclear inflammatory cells and investigated the expression of TH17-associated cytokines mRNA by quantitative real time PCR. We detected significantly higher numbers of IL-17A, and IL-17F immunoreactive cells in AD (especially in chronic) cases compared to controls. We successfully isolated mononuclear inflammatory cells from skin of chronic AD lesions by LCM and have demonstrated the expression of IL-17A and IL-17F mRNA, similarly. Our data suggest that TH17-associated cytokines are highly expressed in chronic AD lesions. These cytokines might be implicated in the pathogenesis of AD, especially chronic lesions. / L'auto-immunité a été proposé de jouer un rôle dans la pathogenèse de la cette maladie. Il a été rapporté que les cellules TH17, récemment décrites, participent à la pathogénèse de certaines maladies auto-immunes. Nous avons examiné l'expression des cytokines associées aux TH17 chez des patients atteints de dermatite atopique et ainsi exploré la présence de cette sous-cellule T en particulier dans les lésions chroniques. Les patients atteints de la DA (aiguë et chronique) ont été recrutés avec un nombre égale de sujets normaux. Des biopsies de la peau ont été prises à partir de chaque groupe. L'expression de l'IL-17A, et IL-17F a été étudié par immunocytochimie. L'identification des Lymphocytes T productrices de l'IL-17A/F a été confirmée par immunofluorescence. Les cellules mononuclées inflammatoires ont été isolées par microdissection (LCM), sur lesquelles, nous avons étudié l'expression de l'ARNm des cytokines associées TH17 par PCR quantitative en temps réel (RT-PCR). Nous avons constaté de manière significative un nombre plus élevé de cellules immunes-réactives IL-17A, et IL-17F dans la maladie DA (en particulier dans les cas chroniques) par rapport aux contrôles. Nous avons réussi à isoler les cellules mononuclées inflammatoires de la peau des lésions chroniques AD par LCM et on a démontré l'expression de l'IL-17A et IL-17F. Nos données suggèrent que les cytokines TH17 associés sont fortement exprimées dans les lésions chroniques de DA. En conclusion, ces cytokines pourraient être impliquées dans la pathogenèse de la maladie dermatite atopique, en particulier chronique.

Breast carcinoma is the most commonly diagnosed cancer among women worldwide, with approximately 1 in 7 expected to be affected during her lifetime. The spread of breast cancer to secondary sites is generally incurable. Bone is the preferred site of metastasis, where the development of a secondary tumour causes severe osteolysis, hypercalcemia and a considerable pain burden. However, how breast cancer cells establish supportive interactions with bone cells is not well understood. We have examined the effects of factors released from MDA-MB-231 and 4T1 breast cancer cells on the differentiation of C57BL6 mouse bone marrow cells. Treatment with cancer-derived factors resulted in a sustained 40–60% decrease in osteoblast differentiation markers, and induced an osteoclastogenic change in the ratio of receptor activator of NF-κB ligand (RANKL) to osteoprotegerin (OPG). Importantly, exposure of bone cells to breast cancer-derived factors stimulated the subsequent attachment of cancer cells to immature osteoblasts. Inhibition of γ-secretase using pharmacological inhibitors DAPT and Compound E completely reversed cancer-induced osteoclastogenesis as well as cancer-induced enhancement of cancer cell attachment, identifying γ-secretase activity as a key mediator of these effects. We next evaluated the effects of breast cancer cells on the energy metabolism of bone cells. Treatment of bone marrow cells with conditioned medium from 4T1 breast cancer cells resulted in an increase in glucose consumption by bone cells, higher mitochondrial transmembrane potential, and a 2.3-fold rise in cellular ATP content. In addition, breast cancer derived factors stimulated the expression of mRNA and protein levels of metabolic sensor, AMP-regulated protein kinase (AMPK). To assess if such change in cell bioenergetics may have consequences for cell differentiation and activity, we used defined models of osteoclastogenesis, and increased precursor metabolic activity by providing excess energy substrates. We have found that an increase in mitochondrial transmembrane potential and cellular ATP levels during osteoclastogenesis resulted in the formation of larger osteoclasts that demonstrate higher resorptive activity. Thus, we have uncovered that osteoblasts act as a critical intermediate of premetastatic signalling by breast cancer cells, and pinpointed γ-secretase as a robust target for developing therapeutics potentially capable of reducing both the homing and progression of cancer metastases to bone. In addition, we have discovered heightened energetics in bone cells exposed to breast cancer cell-released factors, which may contribute to the formation of larger, more active osteoclasts. Modification of the AMPK pathway may prove an important therapeutic target for breast cancer metastasis to bone. / Le cancer du sein est le cancer plus diagnostiqué chez les femmes. On estime qu'environ une femme sur sept en sera affectée. La diffusion du cancer du sein aux emplacements secondaires est généralement incurable. L'os est l'emplacement préféré de la métastase, où le développement d'une tumeur secondaire cause de l'osteolyse, de l'hypercalcemie, et une douleur considérable. Cependant, comment les cellules de cancer du sein établissent des interactions supportifs avec des cellules d'os n'est pas bien compris. Nous avons examiné les effets des facteurs libérés des cellules du cancer du sein MDA-MB-231 et 4T1 sur la différentiation des cellules de moelle de la souris C57BL6. Le traitement avec des facteurs cancer-dérivés a produit une diminution de 40-60% des marqueurs de différentiation d'osteoblast, comparé au traitement par l'acide ascorbique, et a induit un changement osteoclastogenique dans le rapport du RANKL/osteoprotegerin. L'exposition des cellules d'os à des facteurs dérivés du cancer du sein a ensuite stimulé l'attachement des cellules cancéreuses aux osteoblasts non mûrs. L'inhibition du γ-secretase utilisant les inhibiteurs pharmacologiques DAPT et le Compound E a complètement inversé l'osteoclastogenise cancer-induit aussi bien que le perfectionnement cancer-induit de l'attachement de cellules cancéreuses, identifiant l'activité de le γ-secretase comme étant le médiateur principal de ces effets. Nous avons ensuite évalué les effets des cellules cancereuse sur le métabolisme énergétique des cellules d'os. Le traitement des cellules de moelle avec le medium conditionné des cellules du cancer du sein 4T1 a eu comme conséquence une augmentation des mitochondries à haut-potentiel de membrane, une augmentation de 2.3 fois le contenu cellulaire de triphosphate d'adénosine, et une consommation plus rapide du glucose. Ce changement de l'énergétique a été accompagné d'une stimulation d'AMPK dans la protéine et l'ADN messagère. Pour évaluer les effets du statut de haute énergie dans les osteoclasts, nous avons élevé l'énergique des osteoclasts avec du pyruvate de sodium. Cette addition a causée une croissance des osteoclasts, avec des plus grands nucleus, et la résorption de plus de substrat. Ainsi, nous avons découvert l'osteoblast comme étant un intermédiaire clé à la signalisation prémetastatique par des cellules du cancer du sein. Nous avons aussi indiqué le γ-secretase comme cible robuste pour le developpement de thérapeutique potentiellement capable de réduire l'autoguidage et la progression des métastases de cancer à l'os. Additonellement, nous avons découvert l'énergétique intensifiée chez les cellules d'os exposées aux facteurs cellule-libérés par le cancer du sein, qui mène à une osteoclastogenesise plus active et plus importante. La modification de la voie d'AMPK peut s'avérer être une cible thérapeutique importante pour que la métastase de cancer du sein aux os.

Background. Apoptosis is postulated as a mechanism involved in lung ischemia-reperfusion (IR) injury, however, the relative contributions of ischemia and reperfusion are unclear. / Methods. Heart-lung blocks were harvested from New Zealand white rabbits (3.0--4.0 kg) and exposed to 0, 6, or 18 hours of cold ischemia (4°C), followed by 3 hours of reperfusion in an ex vivo model. Terminal dUTP nick-end labeling (TUNEL), the technique used most often for detection of apoptosis, was performed on the tissue sections. / Results. TUNEL demonstrated minimal apoptosis in lungs exposed to 0, 6, or 18 hours of ischemia with insignificant differences (p = 0.6 for 0 h vs. 18 h). After one hour of reperfusion, the level of TUNEL in the 18 hour ischemic tissue was significantly increased (p < 0.05 for 0 h vs. 18 h). During the period of reperfusion, the extent of apoptosis increased in direct proportion to the duration of ischemia; the level of TUNEL staining after 2 hours of reperfusion was significantly greater in the 18 hour ischemic tissue compared to the 6 hour ischemic tissue (p < 0.05), as was the 6 hour compared to the 0 hour (p < 0.01). The hallmark of apoptosis, nucleosomal ladders of 180--200 base pair DNA fragments, corresponded in intensity on gel electrophoresis to the quantitation of TUNEL. The characteristics of apoptotic cells including cell membrane blebbing, chromatin condensation and fragmentation were confirmed by electron microscopy. / Conclusions. These results provide evidence that apoptosis may be a specific feature of IR injury in pulmonary tissue.

Approximately 70% of patients with prostatic cancer develop bone metastases. Metastatic prostate adenocarcinomas are associated with high mortality rates and represent a leading cause of cancer-related deaths among males. To study the host-tumor interactions underlying the predilection of prostate cancer cells for skeletal bone, an experimental model was developed using rat Dunning carcinoma Mat-LyLu cells. Inoculations of these cells into the left ventricle of the heart led to the development of spinal metastases in 100% of inoculated animals. A subline of Mat-LyLu (Mat-LyLu-B5) was subsequently selected through sequential inoculation of bone marrow derived carcinoma cells into the left ventricle of the heart and was found to have an increased metastatic potential compared to the parental line. The possible role of tumor cell adhesion to host cells in the process of bone marrow colonization was then investigated in vitro using the metastatic line and primary cultures of rat bone marrow-derived stromal cells. It was found that the adhesion of the metastatic Mat-LyLu cells to a bone marrow stromal cell culture highly enriched for endothelial cells (BMEC) was significantly higher than the adhesion to other bone-derived cells including non-endothelial BM stromal cells (3x) and osteoblasts (1.4x). It was also significantly higher than the adhesion to rat fibroblasts (5.5x) and to hepatic endothelial cells (7x). The results suggest that the adhesion of prostate carcinoma cells to the bone marrow endothelium may play a role in their metastasis to bone.

In humans, the overall birth frequency of trisomy 21 (Downs syndrome) is 1 per 700 livebirths. The incidence at conception is greater, but more than 80% will not reach term (Connor and Ferguson-Smith 1985). Presumably, numerous factors, genetic and environmental are influencing this process. Therefore, an analysis of the factors modulating the survival of murine aneuploid embryos has been initiated. / A maternal genetic control modulating the survival of murine trisomic embryos has been observed at day 15 of gestation (Vekemans and Trasler 1987; Epstein and Vekemans 1990). To determine whether this modulation is taking place, before or after implantation, the analysis of aneuploid blastocysts has been started. / The frequency of aneuploidy observed at the blastocyst stage has been found not to differ when the maternal genotype varied for both murine chromosomes 19 and 16. Therefore, we can conclude that the maternal genetic control modulating the survival of trisomic embryos at day 15 of gestation is not in effect at the preimplantation stage. / Also we observed that genetic factors are modifying the blastocyst development (e.i. the cavitation process).