Vectors based on adeno-associated virus type 2 (AAV2) are powerful tools for gene transfer and genome editing applications. The level of interest in this system has recently surged in response to reports of therapeutic efficacy in human clinical trials, most notably for those in patients with hemophilia B (ref. 3). Understandably, a recent report drawing an association between AAV2 integration events and human hepatocellular carcinoma (HCC) has generated controversy about the causal or incidental nature of this association and the implications for AAV vector safety. Here we describe and functionally characterize a previously unknown liver-specific enhancer-promoter element in the wild-type AAV2 genome that is found between the stop codon of the cap gene, which encodes proteins that form the capsid, and the right-hand inverted terminal repeat. This 124-nt sequence is within the 163-nt common insertion region of the AAV genome, which has been implicated in the dysregulation of known HCC driver genes and thus offers added insight into the possible link between AAV integration events and the multifactorial pathogenesis of HCC.
Previously, we used a lentiviral vector to deliver furin-cleavable human insulin (INS-FUR) to the livers in several animal models of diabetes using intervallic infusion in full flow occlusion (FFO), with resultant reversal of diabetes, restoration of glucose tolerance and pancreatic transdifferentiation (PT), due to the expression of beta (β)-cell transcription factors (β-TFs). The present study aimed to determine whether we could similarly reverse diabetes in the non-obese diabetic (NOD) mouse using an adeno-associated viral vector (AAV) to deliver INS-FUR ± the β-TF Pdx1 to the livers of diabetic mice. The traditional AAV8, which provides episomal expression, and the hybrid AAV8/piggyBac that results in transgene integration were used. Diabetic mice that received AAV8-INS-FUR became hypoglycaemic with abnormal intraperitoneal glucose tolerance tests (IPGTTs). Expression of β-TFs was not detected in the livers. Reversal of diabetes was not achieved in mice that received AAV8-INS-FUR and AAV8-Pdx1 and IPGTTs were abnormal. Normoglycaemia and glucose tolerance were achieved in mice that received AAV8/piggyBac-INS-FUR/FFO. Definitive evidence of PT was not observed. This is the first in vivo study using the hybrid AAV8/piggyBac system to treat Type 1 diabetes (T1D). However, further development is required before the system can be used for gene therapy of T1D.
Cold exposure is considered to be a form of stress and has various adverse effects on the body. The present study aimed to investigate the effects of chronic daily cold exposure on food intake, body weight, serum glucose levels and the central energy balance regulatory pathway in mice fed with a high-fat diet (HFD). C57BL/6 mice were divided into two groups, which were fed with a standard chow or with a HFD. Half of the mice in each group were exposed to ice-cold water for 1 h/day for 7 weeks, while the controls were exposed to room temperature. Chronic daily cold exposure significantly increased energy intake, body weight and serum glucose levels in HFD-fed mice compared with the control group. In addition, 1 h after the final cold exposure, c-fos immunoreactivity was significantly increased in the central amygdala of HFD-fed mice compared with HFD-fed mice without cold exposure, indicating neuronal activation in this brain region. Notably, 61% of these c-fos neurons co-expressed the neuropeptide Y (NPY), and the orexigenic peptide levels were significantly increased in the central amygdala of cold-exposed mice compared with control mice. Notably, cold exposure significantly decreased the anorexigenic brain-derived neurotropic factor (BDNF) messenger RNA (mRNA) levels in the ventromedial hypothalamic nucleus and increased growth hormone releasing hormone (GHRH) mRNA in the paraventricular nucleus. NPY-ergic neurons in the central amygdala were activated by chronic cold exposure in mice on HFD via neuronal pathways to decrease BDNF and increase GHRH mRNA expression, possibly contributing to the development of obesity and impairment of glucose homeostasis.
PURPOSE. We sought to determine the relative lipase production of a range of ocular bacterial isolates and to assess the efficacy of glycerol monolaurate (GML) in inhibiting this lipase production in high lipase-producing bacteria without affecting bacterial cell growth.METHODS. Staphylococcus aureus, Staphylococcus epidermidis, Propionibacterium acnes, and Corynebacterium spp. were inoculated at a density of 10 6 /mL in varying concentrations of GML up to 25 lg/mL for 24 hours at 378C with constant shaking. Bacterial suspensions were centrifuged, bacterial cell density was determined, and production of bacterial lipase was quantified using a commercial lipase assay kit.RESULTS. Staphylococcus spp. produced high levels of lipase activity compared with P. acnes and Corynebacterium spp. GML inhibited lipase production by Staphylococcal spp. in a dosedependent manner, with S. epidermidis lipase production consistently more sensitive to GML than S. aureus. Glycerol monolaurate showed significant (P < 0.05) lipase inhibition above concentrations of 15 lg/mL in S. aureus and was not cytotoxic up to 25 lg/mL. For S. epidermidis, GML showed significant (P < 0.05) lipase inhibition above 7.5 lg/mL.
CONCLUSIONS.Lipase activity varied between species and between strains. Staphylococcal spp. produced higher lipase activity compared with P. acnes and Corynebacterium spp. Glycerol monolaurate inhibited lipase production by S. aureus and S. epidermidis at concentrations that did not adversely affect bacterial cell growth. GML can be used to inhibit ocular bacterial lipase production without proving detrimental to commensal bacteria viability.
The estrogen levels in the pre and post menstrual phases interact with brain-derived neurotrophic factor in a complex manner, which influences the overall state of the body. To study the role of oestradiol and brain-derived neurotrophic factor in modulating obesity related type 2 diabetes and the interactions between two factors, we enrolled 15 diabetic premenopausal women and 15 diabetic postmenopausal women respectively, the same number of healthy pre and postmenopausal women were recruited as two control groups. The fasting blood glucose, insulin, lipids, estrogen, and brain-derived neurotrophic factor levels were measured through clinical tests. Additionally, we set up obese female mouse model to mimic human trial stated above, to verify the relationship between estrogen and brain-derived neurotrophic factor. Our findings revealed that there is a moderately positive correlation between brain-derived neurotrophic factor and oestradiol in females, and decreased brain-derived neurotrophic factor may worsen impaired insulin function. The results further confirmed that high fat diet-fed mice which exhibited impaired glucose tolerance, showed lower levels of oestradiol and decreased expression of brain-derived neurotrophic factor mRNA in the ventromedial hypothalamus. The level of brain-derived neurotrophic factor reduced on condition that the level of oestradiol is sufficiently low, such as women in postmenopausal period, which aggravates diabetes through feeding-related pathways. Increasing the level of brain-derived neurotrophic factor may help to alleviate the progression of the disease in postmenopausal women with diabetes.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.