Mercury is one of the ubiquitous environmental neurotoxins which causes adverse effects on the development of children's neural system.Considering the severe neurotoxicity of mercury,finding and minimizing the sources of mercury exposure is essential for children's health.Amongst the mercury compounds,the toxicity of organic mercury is the most severe.Methyl mercury (MeHg) is the most detrimental and represents a major source of human exposure of mercury.Recent studies on molecular mechanisms of MeHg neurotoxicity points out that MeHg mainly mediates its toxic effects through the impairment of intraceilular calcium homeostasis,alteration of glutamate homeostasis,and oxidative stress.These concepts provide the biochemical interpreting of MeHg neurotoxicity.This review provides the current information on mercury,including environmental sources,neurotoxicity,and molecular mechanisms of MeHg-induced neurotoxicity.It will be helpful to find some effective ways of interfering children mercury exposure.

Optical coherence tomography (OCT) has developed from time-domain into Fourier-domain OCT (FD-OCT) which indicates clearer details and higher resolution of images. FD-OCT can indicate the structure and pathological changes of each retinal layer, and reveal the retinal external limiting membranes and changes of inner-and outer-segment of visual cells by 3D solid reconstruction. FD-OCT not only provide detailed information of the images for the clinical diagnosis, but also help us investigting the characteristics and pthological mechanisms of ocular fundus diseases, which lead us to a new era of technology of observation on ocualr fundus diseases. In the application, we should pay attention to the significance of different colors of OCT images, and focus on the cohenrence of the position in the image acquistion during the follow-up period. Dynamic observation on the lesions by FD-OCT and aggregated anaylsis of resutls of several imageological examination would be the development direction of imageological examination of ocular fundus diseases.

AIM To observe the effects of different interval administration of exogenous brain derived neurotrophic factor (BDNF) on hypoxic ischemic encephalopathy in neonatal rats. METHODS BDNF (0 5 ?g) was microinjected intracerebroventricularly at 0, 1 and 4 h after the hypoxic ischemic encephal opathy in 7 d neonatal Sprague Dawley rats undergone by ligation of left common carotid artery followed by a 2 5 h inhalation of humidified 8% O 2+92% N 2 at 37℃ immediately after the injury, respectively. Changes of brain edema, levels of malondialehyde (MDA) and neuronal apoptosis at the left cortex and hippocampus were investigated 24 h after the injury. RESULTS The most prominent effect of BDNF was seen in 0 h group with a marked decreases in brain edema and levels of MDA and a significantly alleviated neuronal apoptosis while it was lowered obviously when administered at 4 h after the insult. CONCLUSION BDNF exerts a prominent protective effect on hypoxic ischemic encephalopathy in neonatal rats when given as early as possible after the injury rather than later administration.

Objective To explore the feasibility and advantage of the small figure-L unilateral transternal incision for the treatment of anteri or mediastinal tumor. Methods Twenty-four patients with anteri or mediastinal tumor were enrolled in the study. Under general anesthesia, after a 6 to 10 cm midline skin incision was made, a unilateral figure-L partial ste rnotomy on the side occupied by the tumor was made in the second or third interc ostals space, taking into account the tumor size and location. Tumors were resec ted with excellent exposure. Results All tumors were completely resected during the operation. In 8 cases, tumors encroached on the adjacent lu ng tissue, and lung tissue was partially resected. In 6 cases, tumors invaded th e pericardium, and the pericardium was partially removed. Mean operating time wa s 106 minutes (80~125 minutes). The mean time of hospital stay was 5 days after the operation, and there was no complication. All patients were alive with a mea n follow-up period of 14 months (3~24 months). Conclusion The figure-L unilateral mini-sternotomy is considered as an effective and useful mi nimally invasive approach for anterior mediastinal tumors.

Objective To investigate the characteristics of extreme lateral lumbar disc herniation (ELLDH) with spiral CT multiplanar reformation (MPR), and to determine the effectiveness of MPR in the diagnosis of ELLDH. Method Twenty-five cases with ELLDH underwent conventional CT scans, thin slice spiral scan, and MPR on coronal and sagittal plane. Results Operative findings basically matched the MPR results in 25 ELLDH patients concerning the disc herniation position and compression of the nerve roots. The herniation involved the intervertebral foramina in 15 cases, external intervertebral foramina in 4, both intervertebral and external intervertebral foramina in 3, and intervertebral foramina and vertebral tubes of parity plane in 3. They were demonstrated on MPR as shapes of hillock, circular or trigonal soft-tissue density mass in intervertebral foramen, or outside and tread on the nerve root of parity plane. Among these 25 ELLDH cases, ELLDH was not found by conventional CT scans in 7 cases, but was found by MPR. ELLDH was suspected by conventional CT in 8, and was confirmed to be ELLDH by MPR. ELLDH was revealed by conventional CT scans in 10, but without indications of nerve root compression status, while MPR clearly indicated nerve root compression status. Conclusion MPR has important value in the diagnosis of ELLDH. It can properly identify the ELLDH site, shape, size, and its relation to nerve roots. It is very helpful for the surgeons in the selection of operation method.

Objective To evaluate the variability of four parameters of multi-focal electroretinogram (mERG) a-wave amplitude, b-wave amplitude, a-wave latent period, b-wave latent period. Methods Sixty normal eyes of 46 volunteers were divided into 3 groups of different ages. RETIscan 3 12 system was used to carry out mERG examination. The stimulus matrix of 61 hexagonal elements spanning the central 24?of the visual field. These hexons were scaled with eccentricity and divided into 5 rings. First-order kernel was selected. Results The variability of four parameters of mERG was great. The variability of b-wave latent period was the smallest, its coefficient of variatian was 4.52%～15.62%;that of a-wave latent period held the second place:10.29%~48.67%;that of b-wave amplitude was greater:25.92%~76.11%;that of a-wave amplitude was the greatest:43.82%~88.23%. The results of three groups showed that b-wave amplitude of ring 1 had the smallest variability. Conclusions The variability of latent period is smaller than that of amplitude; the variability of b-wave was smaller than that of a-wave. The longer the centrifugal distance, the lower the amplitude density of a-wave and b-wave. Physiological and anatomical factors might be important for the variability of parameters of multi-focal electroretinogram.

ObjectiveTo study the correlations among age,sex,eye and mERG results.Methods60 normal eyes of 46 volunteers were divided into 6 groups at different ages.RETIscan 3.12 system of Rodenstock was used to carry out mERG examination.ResultsVariation of mERG parameters among normal eyes was significant.Age,sex and eyes have little influence on mERG results,except latency A was longer in male than in female.The size of pupil and fixation were found to influence the results directly.ConclusionsCare should be exercised in explaining the results.Disease history and other examinations shoud be taken into consideration.Attention should be given to the changes in wave-form and vision mountain in addition to amplitudes and latencies.

Objective To explore the effects of brain derived neurotrophic factors (BDNF) on concentrations of cerebral endogenous opioid peptides(EOP)in neonatal rats subject to with hypoxic ischemic brain injury (HIBI). Methods Seven day old Sprague Dawley rats were randomly divided into a HIBI+BDNF group (group A),a HIBI group (group B) and a sham operation group (group C). Models of HIBI were established by use of permanent ligation of the left common carotid artery followed by 2.5 hours ofinhalation of 8%O 2+92%N 2, then 0.5 ?g BDNF was injected into the parietal cerebral ventricle in group A immediately. Contents of dynorphin A 1 13 like, ? endorphin like and leu enkaphalin like immunoreactivities (ir DynA 1 13 , ir ? EP and ir LEK) in cortex and hippocampus were measured at 0, 60, 120 min after administration of BDNF. Results The concentrations of ir DynA 1 13 and ir ? EP in the cortex and hippocampus in group B were increased significantly than those in group C at most time points( P

OBJECTIVE To investigate DNA hypermethylation of human 8-hydroxyguanine glycosy-lase(hOGG1 )gene and and the level of oxidative stress and DNA oxidative damage relations with arse-nic poisoning.METHODS In ende mic coal-pollution-borne arsenism area,Xinren county,Guizhou Province,according to the diagnostic criteria of ende mic arsenism(WS /T21 1 -2001 ),207 people with ende mic arsenism were selected and divided into four groups(The arsenic exposure group:46 cases, mild arsenism group:46 cases,moderate arsenism group:60 cases and severe arsenism group:55 cases).64 residents were selected as controls in a village about 12 km away fro m the ende mic arsenism area.With the informed consent principle,peripheral blood of all respondents was collected in order to analyze DNA methylation.Methylation-specific poly merase chain reaction were respectively performed to analyze hOGG1 Hypermethylation in arsenism respondents.Che mical methods were performed on the activity of super oxide dis mutase (SOD)and glutathione peroxidase (GSH-Px),while the contents of malondialdehyde (MDA)in the blood of patients were measured,and the contents of 8-hydroxy-2′-deox-yguanine(8-OHdG)urine of patients were measured and analysed.On the basis of methylation status are divided into hOGG1 gene methylation group (34 cases)and hOGG1 gene no methylation group (237cases).Analysis was performd on hOGG1 gene DNA methylation and the relationship between oxi-dative stress and arsenic poisoning.RESULTS The positive rates of hypermethylation of hOGG1 were associated with the degree of arsenic poisonin (co mpared with control group,χ2 =23.916,P <0.05, Co mpared with the Ende mic area normal group,χ2 =12.039,P <0.05 ).Co mparing with negative group,SOD〔(85 ±25)kU·L -1 〕,GSH-Px〔(70 ±26)kU·L -1 〕activity and 8-OHdG 〔(22.5 ±6.8)μg·L -1 〕contents were lower〔(1 18 ±41 )kU·L -1 ,(171 ±56)kU·L -1 ,(28.4 ±6.5)μg·L -1 ,P <0.05)〕in positive group.There was no significant difference between the MDA content(P>0.05).CONCLUSION Coal arsenic exposure can cause hOGG1 gene high methylation and oxidation and anti-oxidation system imbalance,causing DNA oxidative damage,it is one of the reasons to pro mote the develop ment of arsenic poisoning occurred.

Objective To report the clinical and genetic characteristics of a dentatorubralpallidoluysian atrophy (DRPLA) pedigree with an onset of cognitive impairment.Methods Clinical data of this pedigree was collected.The numbers of CAG repeats in the exon 5 of atrophin-1 (ATN1) gene were analysed in the proband and the other 4 healthy family individuals.The polymerase chain reaction (PCR) products of the proband underwent cloning-sequencing using an original TA cloning kit.Results There were 5 patients in this family,4 with onset in adult and one in childhood.The proband had an onset manifestation of cognitive impairment,while the other 3 adult patients presented with ataxia.The two-year-old child in the pedigree had myoclonic epilepsy.The proband had 61 CAG repeats in the exon 5 of ATN1 gene.After TA cloning-sequencing of the proband ' s PCR products,there were 2 different numbers of CAG repeats,including 61 and 64.Conclusions The clinical manifestations of DRPLA can have obvious heterogeneity in one family.Some patients present with cognitive impairment.It is very important to test the numbers of CAG repeats of ATN1 gen for DRPLA diagnosis.Somatic mosaicism may be also observed in Chinese DRPLA patients.