Biomedical subjects

Yali Zheng

Publications and source records attributed to Yali Zheng.

6 recordsLinked to original sources

PubMed2006

Cyclin-dependent kinase 5 influences Rohon-Beard neuron survival in zebrafish.

Cyclin-dependent kinase 5 (cdk5), a member of the cyclin-dependent kinase family, is expressed predominantly in post-mitotic cell populations. Unlike the other cdks, cdk5 is abundant and most active in differentiated neurons. Here, we describe the function of a cdk5 ortholog in zebrafish. Cdk5 catalytic activity is meager but present in early stages of development. However, at 24 h post-fertilization (hpf), the activity is remarkably higher and continues to be high through 48 and 72 hpf. Knocking down cdk5 by micro-injection of a specific siRNA resulted in decreased cdk5 protein level accompanied by reduced kinase activity. In the cdk5 siRNA-injected embryos, the number of primary sensory Rohon-Beard (RB) neurons was significantly reduced and there were more apoptotic cells in the brain. These phenotypes were rescued by co-injection of cdk5 mRNA. Within the first two days of development, RB neurons undergo apoptosis in zebrafish. To examine whether cdk5 has a role in RB neuron survival, cdk5 mRNA was injected into the one- to two-cell embryos. In these embryos, RB neuron apoptosis was inhibited compared with the uninjected control embryos. These results suggest that in zebrafish, cdk5 influences RB neuron survival and potentially regulates early neuronal development.

Animals↗

PubMed2006

Squid (Loligo pealei) giant fiber system: a model for studying neurodegeneration and dementia?

In many neurodegenerative disorders that lead to memory loss and dementia, the brain pathology responsible for neuronal loss is marked by accumulations of proteins in the form of extracellular plaques and intracellular filamentous tangles, containing hyperphosphorylated cytoskeletal proteins. These are assumed to arise as a consequence of deregulation of a normal pattern of topographic phosphorylation-that is, an abnormal shift of cytoskeletal protein phosphorylation from the normal axonal compartment to cell bodies. Although decades of studies have been directed to this problem, biochemical approaches in mammalian systems are limited: neurons are too small to permit separation of cell body and axon compartments. Since the pioneering studies of Hodgkin and Huxley on the giant fiber system of the squid, however, the stellate ganglion and its giant axons have been the focus of a large literature on the physiology and biochemistry of neuron function. This review concentrates on a host of studies in our laboratory and others on the factors regulating compartment-specific patterns of cytoskeletal protein phosphorylation (primarily neurofilaments) in an effort to establish a normal baseline of information for further studies on neurodegeneration. On the basis of these data, a model of topographic regulation is proposed that offers several possibilities for further studies on potential sites of deregulation that may lead to pathologies resembling those seen in mammalian and human brains showing neurodegeneration, dementia, and neuronal cell death.

Animals↗

PubMed2005

[Clinical application of multiplanar reconstruction of facial canal: preliminary report].

OBJECTIVE: To study clinical criterion of the anterior positior of mastoid segment and low position of tympanic segment in atresia of external auditory canal. METHOD: Facial canal of 80 cases was measured by multiplanar reconstruction. RESULT: A-B less than 0.4 mm was low position of tympanic segment and E-F less than 5 mm was anterior position of mastoid facial canal in atresia of external auditory canal, there was significant difference between the two subgroups (P < 0.01). CONCLUSION: The first time, the multiplanar reconstruction measurement criterion of facial structures in established. Multiplanar reconstruction system is useful for microsurgery doctors to precisely recognize the mark of high dangerous area in and surroundings.

Adolescent↗

PubMed2003

Cyclin-dependent kinase-5 is involved in neuregulin-dependent activation of phosphatidylinositol 3-kinase and Akt activity mediating neuronal survival.

The phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway plays an important role in mediating survival signals in wide variety of neurons and cells. Recent studies show that Akt also regulates metabolic pathways to regulate cell survival. In this study, we reported that cyclin-dependent kinase-5 (Cdk5) regulates Akt activity and cell survival through the neuregulin-mediated PI 3-kinase signaling pathway. We found that brain extracts of Cdk5-/-mice display a lower PI 3-kinase activity and phosphorylation of Akt compared with that in wild type mice. Moreover, we demonstrated that Cdk5 phosphorylated Ser-1176 in the neuregulin receptor ErbB2 and phosphorylated Thr-871 and Ser-1120 in the ErbB3 receptor. We identified the Ser-1120 sequence RSRSPR in ErbB3 as a novel phosphorylation consensus sequence of Cdk5. Finally, we found that Cdk5 activity is involved in neuregulin-induced Akt activity and neuregulin-mediated neuronal survival. These findings suggest that Cdk5 may exert a key role in promoting neuronal survival by regulating Akt activity through the neuregulin/PI 3-kinase signaling pathway.

Amino Acid Sequence↗

PubMed2002

[Computerized tomographic evaluation of traumatic ossicles disruption].

OBJECTIVE: To investigate the importance of the high resolution computerized tomography of temporal bone in evaluation of traumatic lesions, particularly of the ossicular disruption. METHOD: Ten patients with traumatic ossicles dislocation underwent preoperative CT scanning followed by surgical exploration of the middle ear. RESULT: The radiographic finding was consistent with the operative demonstration for malleoincudal disarticulation (3 ears), incudostapedial dislocation (7 ears), and the fracture of temporal bone (8 ears). CONCLUSION: The incus was the most vulnerable ossicle in the trauma to the middle ear. CT scans can diagnose exactly the damage position in middle ear.

Adolescent↗

PubMedDate not supplied

Temocapril, a long-acting non-SH group angiotensin converting enzyme inhibitor, modulates glomerular injury in chronic puromycin aminonucleoside nephrosis.

The purpose of the present study was to determine whether chronic administration of temocapril, a long-acting non-SH group angiotensin converting enzyme (ACE) inhibitor, reduced proteinuria, inhibited glomerular hypertrophy and prevented glomerulosclerosis in chronic puromycin aminonucleoside (PAN) - induced nephrotic rats. Nephrosis was induced by injection of PAN (15mg/100g body weight) in male Sprague-Dawley (SD) rats. Four groups were used, i) the PAN group (14), ii) PAN/temocapril (13), iii) temocapril (14) and iv) untreated controls (15). Temocapril (8 mg/kg/day) was administered to the rats which were killed at weeks 4, 14 or 20. At each time point, systolic blood pressure (BP), urinary protein excretion and renal histopathological findings were evaluated, and morphometric image analysis was done. Systolic BP in the PAN group was significantly high at 4, 14 and 20 weeks, but was normal in the PAN/temocapril group. Urinary protein excretion in the PAN group increased significantly, peaking at 8 days, then decreased at 4 weeks, but rose again significantly at 14 and 20 weeks. Temocapril did not attenuate proteinuria at 8 days, but it did markedly lower it from weeks 4 to 20. The glomerulosclerosis index (GSI) was 6.21 % at 4 weeks and respectively 25.35 % and 30.49 % at 14 and 20 weeks in the PAN group. There was a significant correlation between urinary protein excretion and GSI (r = 0.808, p < 0.0001). The ratio of glomerular tuft area to the area of Bowman's capsules (GT/BC) in the PAN group was significantly increased, but it was significantly lower in the PAN/temocapril group. It appears that temocapril was effective in retarding renal progression and protected renal function in PAN neprotic rats.

Angiotensin-Converting Enzyme Inhibitors↗