Lentiviral vector-mediated knockdown of SOCS3 in the hypothalamus protects against the development of diet-induced obesity in rats

AIM

Leptin resistance is a feature of most cases of obesity in both humans and rodents. The suppressor of cytokine signalling 3 (SOCS3) is a negative-feedback regulator of leptin signalling involved in leptin resistance; therefore, the suppression of SOCS3 is a potential therapy for leptin resistance in obesity. In the studies, we investigated whether hypothalamic silencing of SOCS3 would attenuate diet-induced obesity in rats.

METHODS

First we established hypothalamic SOCS3-deficient rats through lentiviral vector (LV)-mediated RNA interference (RNAi) technique, then provided a high-fat diet or a chow diet to the rats. After 8 weeks of the diet, the serum leptin and insulin concentrations were measured by RIA, and the gene expressions of SOCS3 and the long form of leptin receptor in hypothalamus were detected by a real time RT-PCR. The leptin-induced Stat3 activation was examined by Western blot.

RESULTS

The RNAi protocol specifically knocked down the expression of SOCS3 mRNA by 50% approximately. The rats treated with LV-SOCS3-shRNA exhibited enhanced leptin-induced Stat3 activation, decreased body weight gain and improved metabolic parameters when exposed to a high-fat diet.

CONCLUSION

Our results provide evidence that the rats treated with hypothalamic SOCS3 silencing are significantly protected against the development of diet-induced obesity and SOCS3 is a potential target molecule for therapeutic intervention of obesity.

Image reconstruction from sparse data in synchrotron-radiation-based microtomography

Synchrotron-radiation-based microcomputed-tomography (SR-μCT) is a powerful tool for yielding 3D structural information of high spatial and contrast resolution about a specimen preserved in its natural state. A large number of projection views are required currently for yielding SR-μCT images by use of existing algorithms without significant artifacts. When a wet biological specimen is imaged, synchrotron x-ray radiation from a large number of projection views can result in significant structural deformation within the specimen. A possible approach to reducing imaging time and specimen deformation is to decrease the number of projection views. In the work, using reconstruction algorithms developed recently for medical computed tomography (CT), we investigate and demonstrate image reconstruction from sparse-view data acquired in SR-μCT. Numerical results of our study suggest that images of practical value can be obtained from data acquired at a number of projection views significantly lower than those used currently in a typical SR-μCT imaging experiment.

Vertebroplasty and kyphoplasty are associated with an increased risk of secondary vertebral compression fractures: a population-based cohort study

To better understand the risk of secondary vertebral compression fracture (VCF) following a vertebroplasty or kyphoplasty, we compared patients treated with those procedures to patients with a previous VCF. The risk of subsequent fracture was significantly greater among treatment patients, especially within 90 days of the procedure.

INTRODUCTION

Predominantly uncontrolled studies suggest a greater risk of subsequent vertebral compression fractures (VCFs) associated with vertebroplasty/kyphoplasty. To further understand this risk, we conducted a population-based retrospective cohort study using data from a large regional health insurer.

METHODS

Administrative claims procedure codes were used to identify patients receiving either a vertebroplasty or kyphoplasty (treatment group) and a comparison group of patients with a primary diagnosis of VCF who did not receive treatment during the same time period. The main outcomes of interest, validated by two independent medical record reviewers, were any new VCFs within (1) 90 days, (2) 360 days, and (3) at adjacent vertebral levels. Multivariable logistic regression examined the association of vertebroplasty/kyphoplasty with new VCFs.

RESULTS

Among 48 treatment (51% vertebroplasty, 49% kyphoplasty) and 164 comparison patients, treated patients had a significantly greater risk of secondary VCFs than comparison patients for fractures within 90 days of the procedure or comparison group time point [adjusted odds ratio (OR) = 6.8; 95% confidence interval (CI) 1.7-26.9] and within 360 days (adjusted OR = 2.9; 95% CI 1.1-7.9).

CONCLUSIONS

Patients who had undergone vertebroplasty/kyphoplasty had a greater risk of new VCFs compared to patients with prior VCFs who did not undergo either procedure.

An Investigation of Compressive-sensing Image Reconstruction from Flying-focal-spot CT Data

Flying-focal-spot (FFS) technique has been used for improving the sampling condition in advanced clinical CT by collecting multiple cone-beam data sets with the focal-spot at different locations at each "projection view". It has been demonstrated that the increased sampling rate in FFS scans can substantially reduce aliasing artifacts in reconstructed images. However, the increase of the sampling density through multiple illuminations at each view can result in the increase of radiation dose to the imaged subject. In this work, we have applied a compressive-sensing (CS)-based algorithm to image reconstruction from data acquired in FFS scans. The results of the study demonstrate that aliasing artifacts observed images reconstructed by use of analytic algorithms can be suppressed effectively in images reconstructed with this CS-based algorithm from only data acquired at one FFS scan.

Obesity reduced the gene expressions of leptin receptors in hypothalamus and liver

The expression of leptin receptor (OB-R) is downregulated by leptin in some cell lines. This study investigated the expressions of leptin receptors at central nerve system and peripheral site in a dietary model of obesity. Rats in the 8 week high-diet and control group were classified based on body weight gain into obese and control groups. Serum leptin and insulin concentrations were measured and gene expressions of short form of leptin receptor (OB-Ra) and long form (OB-Rb) in hypothalamus and liver were detected by RT-PCR. The levels of serum leptin in obese rats were increased compared with control rats (p<0.05). The levels of OB-Ra and OB-Rb gene expressions in both hypothalamus and liver in obese rats were reduced significantly (p<0.01). Serum leptin concentrations of obese rats had a significant negative relationship with both of OB-Ra or OB-Rb gene expression levels in hypothalamus and liver (p<0.01). On the other hand, serum insulin levels had no relationship with OB-Ra or OB-Rb gene expression levels in neither liver nor hypothalamus. Rats with diet-induced obesity have hyperleptinemia and reduced expressions of leptin receptors in hypothalamus and liver. The results suggest that a leptin downregulated OB-R expression is one of leptin resistant mechanisms for maintaining obesity.

Racial differences in survival post cerebral infarction among the elderly

OBJECTIVE

To investigate whether there are differences in poststroke survival between African American and white patients, aged 65 and over, in the United States.

METHODS

A biracial cohort of patients was selected from a random 20% national sample of Medicare patients (age 65 and over) hospitalized with cerebral infarction in 1991, and was followed up to a period of 3 years. The Cox regression model was used for covariate adjustment.

RESULTS

A total of 47,045 patients (including 5,324 African Americans) were identified for our analysis. Compared to white patients, African American patients on average were 6% more likely to die post cerebral infarction. The subpopulation analyses further suggest that African Americans age 65 to 74 had much lower 3-year survival probabilities (15 to 20%) than their white counterparts.

CONCLUSIONS

The authors find evidence of racial disparities in survival post cerebral infarction among the elderly, although the differences by race are not as great as reported elsewhere for stroke incidence and mortality. Future analyses, using more clinically detailed data, should focus especially on whether survival differences by race persist in the young-old (age 65 to 74) population.

HERG K(+) channel activity is regulated by changes in phosphatidyl inositol 4,5-bisphosphate

Autonomic stimulation controls heart rate and myocardial excitability and may underlie the precipitation of both acquired and hereditary arrhythmias. Changes in phosphatidyl inositol bisphosphate (PIP2) concentration results from activation of several muscarinic and adrenergic receptors. We sought to investigate whether PIP2 changes could alter HERG K(+) channel activity in a manner similar to that seen with inward rectifier channels. PIP2 (10 micromol/L) internally dialyzed increased the K(+) current amplitude and shifted the voltage-dependence of activation in a hyperpolarizing direction. Elevated PIP2 accelerated activation and slowed inactivation kinetics. When 10 micromol/L PIP2 was applied to excised patches, no significant change in single channel conductance occurred, indicating that PIP2-dependent effects were primarily due to altered channel gating. PIP2 significantly attenuated the run-down of HERG channel activity that we normally observe after patch excision, suggesting that channel run-down is due, in part, to membrane depletion of PIP2. Inclusion of a neutralizing anti-PIP2 monoclonal antibody in whole cell pipette solution produced the opposite effects of PIP2. The physiological relevance of PIP2-HERG interactions is supported by our finding that phenylephrine reduced the K(+) current density in cells coexpressing alpha1A-receptor and HERG. The effects of alpha-adrenergic stimulation, however, were prevented by excess PIP2 in internal solutions but not by internal Ca(2+) buffering nor PKC inhibition, suggesting that the mechanism is due to G-protein-coupled receptor stimulation of PLC resulting in the consumption of endogenous PIP2. Thus, dynamic regulation of HERG K(+) channels may be achieved via receptor-mediated changes in PIP2 concentrations.

[LC/MS research on the isomers of special melanoma antigen-encoding gene-2 epitope peptide induced by solvent]

To study the influence of different solvent systems on the isomers of melanoma antigen-encoding gene-2(MAGE-2) epitope peptide synthesized by Marrifield's solid synthesis method, MAGE-2(171-179) epitope peptides were pre-treated using ethanol and methanol systems respectively, and then analysed by RP-HPLC/MS, with dimethyl-sulphoxide (DMSO) as control solvent. Results demonstrated that 100% ethanol and 100% methanol solvents could induce the production of isomers of MAGE-2, while 100% DMSO, 50% ethanol and 50% methanol could not. These isomeric peptides could be reversed greatly if treated with trifluoroacetic acid (TFA). The results also showed that the analysis would be distorted and the yield of peptides would decrease dramatically if the peptides were pre-treated with high concentrations of ethanol and methanol before RP-HPLC analysis and preparation. Thus it is suggested that it might be better to decrease the concentration of organic phase in the solvent system for the resolvable hydrophobic peptides, acidified ethanol and methanol might also be better for the highly hydrophobic peptides, and DMSO would be a good solvent for hydrophobic peptides analysis provided that it would not influence the resolving power of chromatography.

Induction of hepatitis B virus-specific cytotoxic T lymphocytes response in vivo by filamentous phage display vaccine

The ability of inducing MHC class I restricted cytotoxic T lymphocytes response in vivo via recombinant filamentous phage was investigated. The recombinant filamentous phage particles that displayed the Hepatitis B virus epitope S(28--39) were injected into BALB/c (H-2d) mice without adjuvants. A MHC class I restricted HBs specific CTL response was found 8 days after injection. The potentiality of using the recombinant filamentous phage as anti-virus vaccine was discussed.

[A study on the bioavailability of fluoride added into milk]

OBJECTIVE

To assess the bioavailability of fluoride added into milk.

METHODS

Eight subjects were studied by testing fluoride levels in blood and urine samples collected after drinking fluoridated milk and fluoridated water respectively, according to pharmacokinetics and cross control method.

RESULTS

The bioavailability of fluoride in fluoridated milk reached 80.2% in blood analysis and 84.8% in urine analysis. The result was about 20.0% lower as compared with fluoridated water.

CONCLUSION

Fluoride bioavailability in fluoridated milk is still high and sufficient.