The projection of the optic nerve to the visual centers of the frog was studied by means of autoradiographic and terminal degenerating method. The results obtained from the two methods were essentially identical in the distribution of the optic term inals in the lateral geniculate body and the pretectum neuropile contralateral to the [~3H]-leucine injected or enucleated eye. There are also some differences:1. In autoradiographic cross sections at certain level of diencephalon, the Bellonci nucleus contralateral to injected eye has a circular outline. It is filled with the optic terminals. Within the Bellonci nucleus and the lateral geniculate body ipsilateral to the injected eye, the distribution of the optic terminals is clear. The Bellonci nucleus contralateral to enucleated eye, revealed by degenerating technique, has a circular outline too, but the optic terminals mainly concentrate on the peripheral of the nucleus. In the central area of the nucleus there are only few degenerating optic terminals. And the Bellonci nucleus and the lateral geniculate body ipsilateral to enucleated eye have only few degenerating optic terminals. The outlines of the two nuclei can hardly be recognized.2. The optic terminals of the superficial layers of the tectum contralateral to injected eye appear to have random distribution revealed by autoradiographic method, while in the sections of the preparation with degenerating method, the optic terminals have a laminar distribution which is very similar to that obtained with modified Cajal's method.3. The appearance of the midbrain tegmental nucleus revealed by autoradiographic method was much clearer than that revealed by degenerating methodIn addition, it has been observed that the number and distribution of degenerating terminals varied with the animal's survival time after the operation.The causes which bring about the differences, the advantages and disadvantages of the two techniques were discussed.

Parts of the left tecta of the frogs were removed in one group. In another group, the left optic nerves of the frogs were cut through the mouth. The first group of animals survived for 12～26days and the second group 11～22 days. Both right and left retinas (with a small piece of optic nerve attached) were sectioned radially at 25?m on a freezing microtome and stained by Ebbesson-Heimer's method which allow degenerating fibers and terminals stained specially. We did not find any evidences showing degeneration. We concluded that centrifugal fibers coming from the centers to the retinas were absent in the frog.

Objective:To evaluate the in vitro release behavior of doxorubicin(Dox)-loaded microspheres and the stability of Dox during encapsulation process and in vitro release.Methods: Dox-loaded microspheres were prepared by double emulsion(W/O/W) method with poly(lactic-co-glycolic acid)(PLGA) as the carrier material.The physical and chemical characteristics of microspheres,including the mean diameter,morphology,drug entrapment efficiency and loading rate,were evaluated.The in vitro release behavior and its influencing factors were determined by ultraviolet spectrophotometry.Dox stability was evaluated by HPLC method during the encapsulation process and in vitro release.Results: The prepared microspheres had a complete spheric shape and dispersive quality.The mean diameter of the microspheres was 85 ?m;the drug entrapment efficiency was 95.1%;and the loading rate was 14.8%.Releasing rate of the microspheres slowed down with the increase of PLGA concentration and the decrease of W/O value.The encapsulation process had no obvious effect on the stability of Dox,while Dox degraded during in vitro release as the prolongation of time.On day 10,the peak area of degraded material accounted for 2.46%.Conclusion: Dox can be encapsulated in the microspheres by double emulsion method and different release rates of Dox can be achieved by adjusting PLGA concentration and W/O volume ratio.

HRP solution (33%) was injected into the left superior colliculus of 21 adult albino rats. 1-2 days after injection, the animal was sacrificed. Brains were frozen sectioned and processed according to. DAB- or TMB-method. The labeled neurones were examined in the right superior colliculus and other areas of the brain. The resu ts are as follows:1. No matter where the HRP was injected (either in the rostral or caudal part of the superior colliculus or thepart between them) HRP labeled neurones were always observed on the opposite superior colliculus if the injection sites reached layers deeper than the stratum oPticum. The locations of the labeled neurones corresponded roughly to the sites of HRP injections. However, no HRP labeled neurones were observed when the core of HRP deposites was restricted to layers superficial to the stratum griseum intermediale.2. Of all labeled neurones, 53.6% were located in the stratum griseum intermediale, 16.5% in the stratum opticum. The rest were in deeper layers. In no case were HRP labeled neurones observed in the stratum zonale or stratum griseum superficiale.3. Labeled neurones could be classified morphologically into vertical fusiform, horizontal fusiform and multipolar neurones.4. In addition to the visual cortex, labeled neurones were also found in the inferior colliculi, paralemniscal nuclei, dorsal nuclei of the lateral lemniscus, substantia nigrae and lateral tegmental nuclei bilaterally. Labeled neurones were also found in the ipsilateral ventral nucleus of the lateral geniculate body, contralatera pretectal area and reticular formation.

In order to investigate the distribution and other features of callosal neurons inthe visual areas,12 adult albino rats were used in a series of experiments,in whichHRP(30～50%,DAB brown reaction)was injected into one hemisphere and theretrograde labelled cells were observed in the other hemisphere.1.Hardly any labelled neuron was found in contralateral visual cortices whenthe injections were made at sites within 3.6 mm from the midline of the brain.However,when the injections were made at sites 4～6 mm from the midline,manylabelled neurons could be observed.2.Generally,most labelled cells aggregated near the border between area 17 and18a.In area 18a numerous cells were labelled,which distributed in the form ofincontinuous patches.In the proper of area 17,however,less labelled cells werefound.3.A gross topographical correlation was observed between locations of injectionand labelling on the two hemispheres.4.The labelled cells were found in all cortical layers except layer Ⅰ.In area 17they were mainly in layers Ⅳ and Ⅴ,while in area 18 a they were found mainly inlayers Ⅲ,Ⅳ and Ⅴ.5.Some callosal neurons were lightly labelled.For these cells,only the outlinesof the cell body could be seen even under dark-field microscope.The diameters ofthese cells were about 8～10?m.A few cells were as large as 16?m in diameter.Other labelled neurons could be seen with both dark-field and bright-field illumina-tions.They were identified as pyramidal,multipolar bipolar and granular cells accordingto the shape of the cell bodies and the pattern of dendrites.The majority of labelledcells were pyramidal cells,with a long apical dendrite to the pia surface,10～20?min diameter.Other ceils were 10～20?m for multipolar cells,and less than 10?m forgranular cells.Comparisons were made between the above results and the physiological studies.

Objective To investigate the antimicrobial resistance mechanisms and genetic homogeny of Salmonella from community acquired infections in Shenzhen,China.Methods Ninety-three of Salmonella were isolated from 2002 to 2007 at Shenzhen People's Hospital,China.PCR and DNA sequencing were used to investigate the mutation in QRDR of the gyrA,gyrB,parC and parE.Plasmid mediated quinolone resistance genes including qnr and aac(6')-Ib-cr,β-lactamase genes including blaTEM,blaSHV,blaOXA, blaCTX-M, and class 1 integron were detected. All isolates were typed by PFGE. Results S. enterica typhi and S. enterica paratyphi A were susceptible to ampicillin, chloramphenicol, trimethoprim/sulfamethoxazole, ceftriaxone and ciprofloxacin, with the susceptible rate of 96%-100%. Fifty-two percent (13/25) of S. enterica typhi and 95% (61/64) of S. enterica paratyphi A were resistant to nalidixic acid. Twenty-four percent (6/25) of nalidixic acid-resistant S. enterica typhi and 94% (60/64) of nalidixic acid-resistant S. enterica paratyphi A showed decreased susceptibility to ciprofloxacin (MIC of 0. 125-1 μg/ml).All nalidixic acid-resistant (susceptible to ciprofloxacin ) Salmonella (NARS) isolates had a single substitution in the QRDR of GyrA, and 91% (68/75) of these isolates carried the substitution Ser83Phe in GyrA. Two mutations in the QRDR of GyrA were detected in both of two ciprnfloxacin-resistant Salmonella,with the additional one mutation in the QRDR of parC. Plasmid mediated quinolone resistance genes including qnr and aac(6')-lb-cr were not detected in any isolate. The blaCTX-M-14 gene was detected in a ceftriaxoneresistant isolate of S. enterica paratyphi A, with ISEcpl located on the upstream of it. Three muhidrugresistant strains of Salmonella all carried one 1 900 bp classⅠ integron gene cassette dhfrⅫ-orfF-aadA2,with the additional one β-lactamase gene of blaTEM-1, or blaOXA-30. Twenty-two distinct PFGE patterns were observed among twenty-five S. enterica typhi. The PFGE patterns of sixty-four S. enterica paratyphi A showed limited genetic diversity (average similarity of 91% ). Ninety investigated inpatients were infected in the community. Six patients infected by S. enterica paratyphi A had a travel history before infection. Conclusions Nalidixic acid-resistant S. enterica typhi and S. enterica paratyphi A are highly prevalent in Shenzhen,China. The mutation in the QRDR of GyrA is the prevalent mechanism responsible for the resistance to nalidixic acid in Slmonella. The great genetic similarity among S. enterica paratyphi A isolates indicates endemic disease from the presence of a single clone over 6-year period.

Objective To study the epidemiological features of Cryptococcus neoformans and Cryptococcus gattii isolated from clinical samples in Shenzhen and to elucidate the distribution of species,varieties,genotypes and mating types within the strains tested.Methods The strains involved in this study were 55 cryptococcal strains isolated from our clinical samples.The canavanine-glycine bromthymolblue (CGB) culture was performed to distinguish Cryptococcus neoformans from Cryptococcus gattii.The genotype was characterized by polymerase chain reaction (PCR) fingerprinting with primer M13.The Cryptococcus gattii species and varieties of grubii and neoformans together with two opposite mating type α and a were identified by PCR with variety-specific and mating type-specific primers.The GEF1-restriction fragment length polymorphism analysis was conducted to simultaneously determine the genotype and mating types of strains tested.The sequence type of IGS1 region was analyzed for the VG Ⅱ genotype.Results Of the 55 tested cryptococcal strains,52 were Cryptococcus neoformans,all of which were var.grubii,genotype VN Ⅰ and mating type α.The remaining 3 strains were Cryptococcus gattii,among which,one was genotype VG Ⅰ and mating type α,and two were genotype VG Ⅱ and mating type α.The two VGⅡ genotype strains belonged to the sequence type Ⅱ.Conclusions The strains belonging to the Cryptococcus neoformans var.grubii,genotype VN Ⅰ and mating type α predominate in causative pathogens of cryptococcosis in Shenzhen.Cryptococcus gattii accounts for minority of the cryptococcal isolates,and the highly pathogenic VG Ⅱ genotypes in foreign countries are also characterized.The sequence types of IGS1 region of the two VG Ⅱ strains are in accord with VG Ⅱb sub-genotype.

OBJECTIVE To investigate the antimicrobial susceptibility of 9 antimicrobial agents and multidrug(resistance)(MDR) phenotype among Acinetobacter baumannii isolated from hospitalized patients.METHODS Disk diffusion method was used to detect the inhibitory zone diameter of 9(antimicrobial) agents to 221 strains of A.baumannii.according to standard from NCCLS in South China during 2002 to 2004.RESULTS 25.3% and 26.4% of isolates from ICU patients showed resistance to(imipemem) and meropemem,respectively,and the resistance rates were greater among the(isolates) from ICU(patients) than those from non-ICU inpatients by 13.4% and 12.2 %(P

OBJECTIVE To investigate the prevalence of multidrug resistance(MDR) mechanisms of Staphylococcus haemolyticus against oxacillin,gentamycin and erythromycin.METHODS Agar dilution method was performed to detect the minimal inhibition concentration(MIC) of 3 antimicrobial agents against 63 strains of S.haemolyticus,and the resistance genes of mecA,aac(6′)+aph(2″),ermA,ermB,ermC and msrA/msrB were investigated by PCR in all clinical isolates.RESULTS mecA Gene was detected in 62 isolates of meticillin-resistant S.haemolyticus(MRSH),and aac(6′)+aph(2″) gene was found in 50 isolates resistant to gentamicin,and the most prevalence erythromycin resistance gene in S.haemolyticus was msrA/msrB(58.7%),followed by ermC(31.7%).Among the 43 MDR strains,the more commonly encountered three genes were mecA,aac(6′)+aph(2″) and msrA/msrB(58.1%)or ermC(20.9%),and 8 isolates(18.6%) were found harboring four genes of mecA,aac(6′)+aph(2″),ermC and msrA/msrB.CONCLUSIONS The mecA,aac(6′)+aph(2″),msrA/msrB and ermC genes are main resistance mechanisms against oxacillin,gentamicin and erythromycin in mutidrug resistant S.haemolyticus.

OBJECTIVE To investigate the susceptibilities of Staphylococcus aureus and Enterococcus isolated from Shenzhen Hospital during 2005 to 2006 to 17 antimicrobial agents.METHODS The minimal inhibitory concentrations(MICs) of 17 antibacterial agents were determined by agar dilution method,WHONET5.3 software was used to analyze the data.RESULTS The prevalence of meticillin-resistant S.aureus(MRSA) was 20.7%.Vancomycin and teicoplanin remained very high activity against MRSA(100%),with the MIC50 and MIC90 of 0.5 and 1 ?g/ml,respectively.Fluoroquinolones(ciprofloxacin,levofloxacin and gatifloxacin),trimethoprim/sulfamethoxazole,erythromycin,and clindamycin showed very low activity against MRSA(0-33.3%).The most active agent against Enterococcus faecalis was vancomycin and teicoplanin(100.0%),followed by piperacillin/tazobactam,imipenem and ampicillin(97.2-100.0%).E.faecium showed high resistance to various agents,except to vancomycin and teicoplanin(susceptible rate 100.0%).Cross-resistance to fluoroquinolones was found among MRSA,MSSA,E.faecalis,and E.faecium.CONCLUSIONS MRSA and E.faecium isolated from our hospital showed high resistance to multiple antimicrobial agents except vancomycin and teicoplanin.