The changes of glucose and lipid metabolism in overweight middle-aged cynomolgus monkeys.

BACKGROUND: Excessive weight gain has been observed in middle-aged cynomolgus monkeys. This study was designed to investigate the metabolic characteristics in overweight monkeys. METHODS: A total of 26 cynomolgus monkeys were grouped based on gender and body weight. Overweight was operationally defined as body weight heavier than 9.6 kg in males and 7.5 kg in females. They were monitored for glucose and insulin in fasting state, serum parameters, and somatometric measurements. RESULTS: Higher measurements of weight, body mass index (BMI), waist, hip, and waist/hip ratio (WHR) were the somatometric characteristics of overweight monkeys. Abdominal fat deposition was more prominent in females. Elevated total cholesterol, HDL-C, LDL-C, and fasting glucose were observed in female overweight monkeys. Impaired insulin sensitivity occurred in overweight monkeys. CONCLUSIONS: Overweight could result in impaired insulin sensitivity. The metabolic changes were more prominent in female overweight monkeys.

Advanced glycation end products and ultrastructural changes in corneas of long-term streptozotocin-induced diabetic monkeys.

PURPOSE: The purpose of this study was to investigate the ultrastructural corneal changes of chronic diabetic monkeys and explore the relationship between advanced glycation end products and ultrastructural changes in diabetic corneas. METHODS: A total of 8 cynomolgus monkeys were used in this experiment. Four monkeys were induced into insulin-dependent diabetes mellitus for 4 years. Four age-matched healthy monkeys were used as the controls. Ultrathin sections obtained from the corneas were examined by transmission electron microscopy. RESULTS: Advanced glycation end product immunoreactivity was observed in the epithelial cells, epithelial basement membrane, and stromal keratocytes of diabetic corneas, whereas advanced glycation end product immunoreactivity was not found in the corresponding area in normal corneas. Abnormal collagen fibril bundles of variable thickness were identified in corneal stroma in all diabetic monkeys. Epithelial and endothelial cell degeneration was also observed in 1 diabetic monkey. CONCLUSIONS: Abnormal aggregates of collagen fibrils in stromal matrix were common among long-term diabetic monkeys, and the formation of the abnormal collagen fibril aggregates might result from excessive nonenzymatic glycosylation.

Inducible and reversible transgene expression in human stem cells after efficient and stable gene transfer.

We report here a lentiviral vector system for regulated transgene expression. We used the tetracycline repressor fused with a transcriptional suppression domain (tTS) to specifically suppress transgene expression. Human cells were first transduced with a tTS-expressing vector and subsequently transduced with a second lentiviral vector-containing transgene controlled by a regular promoter adjacent to a high-affinity tTS-binding site (tetO). After optimizing the location of the tetO site in the latter vector, we achieved a better inducible transgene expression than the previous lentiviral vectors using the tetracycline repressor systems. In this new system, the transgene transcription from a cellular promoter such as EF1alpha or ubiquitin-C promoter is suppressed by the tTS bound to the nearby tetO site. In the presence of the tetracycline analog doxycycline (Dox), however, the tTS binding is released from the transgene vector and transcription from the promoter is restored. Thus, this system simply adds an extra level of regulation, suitable for any types of promoters (ubiquitous or cell-specific). We tested this tTS-suppressive, Dox-inducible system in 293T cells, human multipotent hematopoietic progenitor cells, and three human embryonic stem cell lines, using a dual-gene vector containing the green fluorescent protein reporter or a cellular gene. We observed a tight suppression in the uninduced state. However, the suppression is reversible, and transgene expression was restored at 5 ng/ml Dox. The lentiviral vectors containing the tTS-suppressive, Dox-inducible system offer a universal, inducible, and reversible transgene expression system in essentially any mammalian cell types, including human embryonic stem cells.