Cyclin-dependent Kinase 5 Regulates Cortical Neurotransmission and Neural Circuits Associated with Motor Control in the Secondary Motor Cortex in the Mouse.

Cyclin-dependent kinase 5 (Cdk5) is a regulator of axon growth and radial neuronal migration in the developing mouse brain, and it plays critical roles in cortical structure formation and brain function. However, the function of Cdk5 in cortico-cortical and cortico-sensorimotor networks in the adult remains largely unknown. In this study, we investigated the function of Cdk5 in the rostral secondary motor cortex (M2) in the male mouse using CRISPR/Cas9 gene editing and somatic brain transgenesis, to produce M2-specific knockdown of Cdk5 in neurons in the male mouse. Mouse deficient in Cdk5 in the M2 exhibited a reduction in both the number of functional synapses and the total basal dendritic length, as well as motor dysfunction. Furthermore, whole-cell patch-clamp recordings in layer V green fluorescent protein (GFP)-tag pyramidal neurons revealed a decrease in the frequency and amplitude of miniature EPSCs and miniature IPSCs, as well as a reduction in the population synaptic responses (fEPSPs) in these mice. Specifically, retrograde labeling showed that Cdk5 knockdown in the M2 caused a reduction in long-range projections to the M2 from the thalamus/prefrontal cortex and claustrum. Collectively, our findings show a new regulatory role of Cdk5 in neural circuit maintenance, and that the changes in neural transmission and circuits in the mice with Cdk5 knockdown in the M2 likely contribute to the motor dysfunction in these animals.

Neuroprotective effects of madecassoside against focal cerebral ischemia reperfusion injury in rats.

Madecassoside, a triterpenoid derivative isolated from Centella asiatica, exhibits anti-inflammatory and antioxidant activities. We investigated its neuroprotective effect against ischemia-reperfusion (I/R) injury in cerebral neurons in male Sprague-Dawley rats. Madecassoside (6, 12, or 24mg/kg, i.v.) was administered 1h after the start of reperfusion, and neurological deficit score and infarct volume were evaluated 24h later. Neuronal apoptosis was assessed by performing terminal deoxynucleotidyl transferase-mediated dUTP-nick end labeling (TUNEL) staining, and pathological brain damage was estimated by performing hematoxylin and eosin staining. Serum levels of malondialdehyde, superoxide dismutase activity, reduced glutathione levels, and nitric oxide levels were also determined. mRNA and protein expression of pro-inflammatory cytokines (Interleukin-1ß/6, and tumor necrosis factor-α) were measured by real-time RT-PCR and ELISA, respectively; NF-κB p65 expression was determined by western blotting. Madecassoside significantly reduced brain infarct area, resolved neurological deficit, and ameliorated neuronal apoptosis. It also significantly reduced the levels of malondialdehyde and nitric oxide, and augmented the antioxidant activity in rats subjected to cerebral I/R. Moreover, the levels of pro-inflammatory cytokines and NF-κB p65 significantly reduced after madecassoside treatment. These results indicate that madecassoside is neuroprotective and may be useful in reducing the damage caused by stroke.

Protective effect of exogenous matrix metalloproteinase-9 on chronic renal failure.

Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) have pivotal functions in extracellular matrix turnover and are involved in chronic kidney diseases. However, the exact functions of MMPs in chronic renal failure (CRF) have yet to be demonstrated. The aim of the present study was to examine the effects of MMP-9 on CRF. An adenine-induced model of CRF was generated in rabbits. Following the injection of MMP-9 into the renal arteries of the rabbits, significant improvements in renal morphology and serum levels of creatinine and urea nitrogen were observed. Furthermore, MMP-9 administration was shown to decrease the serum TIMP-1 concentration and upregulate renal MMP-9 expression. These results demonstrate a directly protective role for MMP-9 in CRF.

Gas chromatographic-tandem mass spectrometric analysis of ß-lyase metabolites of sulfur mustard adducts with glutathione in urine and its use in a rabbit cutaneous exposure model.

A method for quantitation of ß-lyase metabolites of sulfur mustard (SM) adducts with glutathione has been developed and validated using gas chromatography-tandem mass spectrometry (GC-MS/MS). The linear range of quantitation was 0.1-1000ng/mL in urine with a method detection limit of 0.02ng/mL. The method was applied in a rabbit exposure model. Domestic rabbits were cutaneously exposed to neat liquid SM in three dosage levels, and the ß-lyase metabolites in urine were determined as 1,1'-sulfonylbis[2-(methylthio)ethane] (SBMTE). The study showed that even though more than 99% of the total amount of ß-lyase metabolites was excreted in the first week after exposure, the ß-lyase metabolites of SM adducts with glutathione could be detected in urine from rabbits for up to 3 or 4 weeks after the SM cutaneous exposure. For high dosage group (15mg/kg, 0.15 LD50), the mean concentration of SBMTE detected was 0.32ng/mL on day 28. For middle (5mg/kg, 0.05 LD50) and low (2mg/kg, 0.02 LD50) dosage groups, the mean concentrations of SBMTE were 0.07ng/mL and 0.02ng/mL on day 21, respectively. The data from this study indicate that the method is sensitive and provides a relatively long time frame for the retrospective detection of SM exposure.

[Predictive value of human fatty acid binding protein for myocardial ischemia and injury in perioperative period of cardiac surgery].

OBJECTIVE: To evaluate the value of human fatty acid binding protein (h-FABP) in predicting myocardial ischemia and injury in the perioperative period of cardiac surgery, we observed the dynamic changes of h-FABP in perioperative period of patients underwent coronary artery bypass grafting and ventricular septal defects repairing surgery, and evaluated the relationship of h-FABP and ischemia modified albumin (IMA), CK-MB, cTnI. METHODS: Patients underwent coronary artery bypass grafting (n=30) and ventricular septal defect repairing (n=30) surgery between February 2008 and December 2008 were included in this study. Venous blood sample was obtained at preoperative, aortic clamping, aortic unclamping of 10 min, 2 h, 6 h, 12 h, 24 h for the measurements of h-FABP, IMA, cTnI and CK-MB. RESULTS: h-FABP and IMA changed in the same way at various examined time points, h-FABP changes also paralleled cTnI and CK-MB changes, h-FABP peaked early during myocardial ischemia and injury and returned to baseline level at 2 h post myocardial ischemia and injury. Linear correlation analysis showed that the peak value of h-FABP was positively correlated with IMA, CK-MB and cTnI in both CABG group (r = 0.948, 0.964 and 0.961, P < 0.05) and in the VSD group (r = 0.986, 0.978 and 0.957). CONCLUSIONS: h-FABP is an early diagnostic parameter reflecting perioperative myocardial ischemia and injury in cardiac surgery. Quantitative h-FABP monitoring could predict the severity of myocardial ischemia and injury early during cardiac surgery.