Cannabinoid receptor system regulates ion channels and synaptic transmission in retinal cells / 生理学报

Endocannabinoid receptor system is extensively expressed in the vertebrate retina. There are two types of cannabinoid receptors, CB1 and CB2. Activation of these two receptors by endocannabinoids N-arachidonoylethanolamide (anandamine, AEA) and 2-arachidonyl glycerol (2-AG) regulates multiple neuronal and glial ion channels, thus getting involved in retinal visual information processing. In this review, incorporating our results, we discuss the modulation of cannabinoid CB1 and CB2 receptors on retinal neuronal and glial ion channels and retinal synaptic transmission.

Replantation for complete amputated finger composite lateral tissues / 中国骨伤

<p><b>OBJECTIVE</b>To explore the clinical therapeutic effect and safety of application of Ilizarov technique combined with flap instant expansion technique in correcting tibia angular deformity combined with skin contracture by one stage.</p><p><b>METHODS</b>From January 2010 to January 2013, 30 cases of tibial deformity with skin contracture were corrected by Ilizarov technique combined with flap instant expansion technique at one stage, including 21 males and 9 females with an average age of(40.2±5.5) years ranging from 25 to 60 years. All patients underwent regular reexamination of X-ray. After removal of the Ilizarov external fixation, knee joint function were assessed by American Hospital for Special Surgery (HSS) scoring criteria, and the pain was evaluated by visual simulation score(VAS).</p><p><b>RESULTS</b>All patients were followed up for 6 to 35 months with an average of 22 months. Among them, the incision of 29 patients were primary healing, 1 patient had wound infection complicated by osteomyelitis, 2 patients complicated with fixed screw loosening, there were no expanded skin flap necrosis and neurovascular injury symptoms. The external fixators were removed at 4 to 7 months after operation with an average of(5.2±1.1) months. Correction angle was 10° to 35° degrees with an average of (25.5±3.5)°. HSS total score was 92.5±6.6 and the result was excellent in 25 cases, good in 4 cases, fair in 1 case; the VAS score was 1.2±1.5.</p><p><b>CONCLUSIONS</b>The application of Ilizarov technique combined with flap instant expansion technique is a good method for correction of tibial angular deformity with skin contracture by one stage, with a shorter time of external fixation frame, without skin necrosis and neurological symptoms, early load exercise and improve the limb function.</p>

Glutamate receptor-mediated retinal neuronal injury in experimental glaucoma / 生理学报

Glaucoma, the second leading cause of blindness, is a neurodegenerative disease characterized by optic nerve degeneration related to apoptotic death of retinal ganglion cells (RGCs). In the pathogenesis of RGC death following the onset of glaucoma, functional changes of glutamate receptors are commonly regarded as important risk factors. During the past several years, we have explored the mechanisms underlying RGC apoptosis and retinal Müller cell reactivation (gliosis) in a rat chronic ocular hypertension (COH) model. We demonstrated that elevated intraocular pressure in COH rats may induce changes of various signaling pathways, which are involved in RGC apoptosis by modulating glutamate NMDA and AMPA receptors. Moreover, we also demonstrated that over-activation of group I metabotropic glutamate receptors (mGluR I) by excessive extracellular glutamate in COH rats could contribute to Müller cell gliosis by suppressing Kir4.1 channels. In this review, incorporating our results, we discuss glutamate receptor- mediated RGC apoptosis and Müller cell gliosis in experimental glaucoma.

Progress in electrophysiological studies of retinal ganglion cells / 生理学报

The knowledge about electrophysiological properties of retinal ganglion cells (RGCs), as well as modulation of these properties, is important not only for understanding the unique physiological functions of RGCs under normal conditions, but also for exploring the cellular mechanisms of retinal neurodegeneration diseases, such as glaucoma. In this paper, we reviewed the progress in electrophysiological studies of RGCs by using patch-clamp techniques, concerning the voltage-gated ion channels, the ligand-gated ion channels and the effects of neuromodulators on these channels.

Activation of cannabinoid CB1 receptors modulates evoked action potentials in rat retinal ganglion cells / 生理学报

Activation of cannabinoid CB1 receptors (CB1Rs) regulates a variety of physiological functions in the vertebrate retina through modulating various types of ion channels. The aim of the present study was to investigate the effects of this receptor on cell excitability of rat retinal ganglion cells (RGCs) in retinal slices using whole-cell patch-clamp techniques. The results showed that under current-clamped condition perfusing WIN55212-2 (WIN, 5 μmol/L), a CB1R agonist, did not significantly change the spontaneous firing frequency and resting membrane potential of RGCs. In the presence of cocktail synaptic blockers, including excitatory postsynaptic receptor blockers CNQX and D-APV, and inhibitory receptor blockers bicuculline and strychnine, perfusion of WIN (5 μmol/L) hardly changed the frequencies of evoked action potentials by a series of positive current injection (from +10 to +100 pA). Phase-plane plot analysis showed that both average threshold voltage for triggering action potential and delay time to reach threshold voltage were not affected by WIN. However, WIN significantly decreased +dV/dtmax and -dV/dtmax of action potentials, suggestive of reduced rising and descending velocities of action potentials. The effects of WIN were reversed by co-application of SR141716, a CB1R selective antagonist. Moreover, WIN did not influence resting membrane potential of RGCs with synaptic inputs being blocked. These results suggest that activation of CB1Rs may regulate intrinsic excitability of rat RGCs through modulating evoked action potentials.

Roles of retinal Müller cells in health and glaucoma / 生理学报

In the vertebrate retina, Müller cells are principal glial cells which stretch across the whole thickness of the retina and contact with the somata and processes of all retinal neurons, thus forming an anatomical and functional link between glial cells and retinal neurons. Numerous studies have shown that Müller cells express various neurotransmitter receptors, transporters, ion channels and enzymes that are relative to cellular activities. In addition, the cells also release factors, such as D-serine and glutamate etc., to regulate the neuron excitability. Therefore, retinal Müller cells may play more curious roles in addition to supporting the retinal neurons. The information exchange and interaction between Müller cells and neurons may regulate and maintain retinal neuronal functions. In the glaucomatous retina, Müller cells are reactivated (gliosis). Reactivated Müller cells undergo a variety of changes in cellular physiology, biochemistry and morphological features. Meanwhile, the reactivated Müller cells may produce and release cytotoxic factors, such as nitric oxide (NO), tumor necrosis factor-α (TNF-α), reactive oxygen species (ROS) and prostaglandin E2 (PGE2), thus involving in the induction of retinal ganglion cell apoptosis and death. Here, we reviewed the physiological properties of retinal Müller cells, and the functional changes of Müller cells in the glaucomatous retina.

Roles of cyclin-dependent kinase 5 in central nervous system development and neurodegenerative diseases / 生理学报

Cyclin-dependent kinase 5 (Cdk5) is a proline-directed serine/threonine kinase, and plays multiple roles in neuron development and synaptic plasticity. The active form of Cdk5 is found primarily in the central nervous system (CNS) due to its activator proteins p35 or p39 ubiquitously expressed in neuronal cells. Normally, the transcription and activity of Cdk5 are strictly regulated by several ways. In the physiological condition, Cdk5 plays a key role in the CNS development by phosphorylating the specific serine or threonine site of numerous substrate proteins that are closely associated with the neuronal migration, synaptogenesis, synaptic transmission as well as synaptic plasticity. Under pathological conditions, p35 can be truncated into p25, which can strongly and consistently activate Cdk5, change the cellular localization of Cdk5 and lead to neuronal death ultimately. The increasing evidence has showed that Cdk5 is involved in the pathogenesis of many neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease and amyotrophic lateral sclerosis etc., indicating that Cdk5 may be a potential target in the treatment of the neurodegenerative diseases. In this article, we reviewed the recent progress regarding the roles of Cdk5 in CNS development and neurodegenerative diseases.

Characteristics of transgenic tomatoes antisensed for the ethylene receptor genes LeETR1 corrected and LeETR2 corrected / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Two stable transformed lines containing antisense LeETR1 [corrected] or LeETR2 [corrected] sequences and their hybridized line were investigated to determine the effect of LeETR1 [corrected] and LeETR2 [corrected] specificity in the ethylene receptor family in tomato (Lycopersicon esculentum Mill.) on ethylene signaling. The transgenic line ale1 containing antisense LeETR1 [corrected] displayed shorter length of seedling grown in the dark and adult plant in the light, severe epinastic petiole, and accelerated abscission of petiole explant and senescence of flower explant, compared with its wild type B1. The transgenic line ale2 containing antisense LeETR2 [corrected] also exhibited shorter hypocotyls and slightly accelerated abscission. The phenotypes of cross line dale of LeETR1 [corrected] and LeETR2 [corrected] were close to ale1 in many aspects. These results suggested that LeETR1 [corrected] probably plays a relatively important role in ethylene signaling of tomato growth and development.

Characteristics of fruit ripening in tomato mutant epi / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

The characteristics of fruit ripening and expression of ripening-related genes were investigated in epi, an ethylene overproduction mutant of tomato (Lycopersicon esculentum Mill.). The epi produces apparently more ethylene than its wild type VFN8 at every stage of vegetative and fruit growth and ripening; compared to VFN8, the epi fruit showed higher CO2 evolution, faster descending of chlorophyll, slightly quicker increase of carotenoid and lycopene, and faster reduction in pericarp firmness during maturation and ripening; and the mRNAs of three ripening-related genes including E8, pTOM5 and pTOM6 were at higher levels in epi. The ripening-related characteristics changing of the fruit are consistent with the increase of ethylene production and ripening-related genes expression. These results suggest that epi mutation possibly did not affect the ethylene perception and signaling during fruit ripening, and that the modified characteristics of fruit ripening possibly resulted from the ethylene overproduction and increased expression of ripening-related genes.