To Save Pangolins: A Nutritional Perspective.

Pangolins are one of the world's most trafficked mammals. Since pangolins are highly adapted to ants and termites, they are important for controlling forest termite infestations. In addition to their ecological value, pangolins have economic and medicinal value. Currently, poaching and habitat destruction have radically reduced the number of pangolins, and Manis pentadactyla, Manis javanica, and Manis culionensis are now considered the most threatened pangolin species. In addition to the control of hunting and illegal trade, ex situ breeding is also a useful conservation method. However, many technical obstacles still limit the success of ex situ pangolin breeding. The special feeding traits of pangolins require a diet that meets nutritional and ethological needs. Based on the existing literature and practical experience, this review aims to compare the natural diet and successful diet in the human care of pangolins, to outline the key factors of successful ex situ maintenance from a dietary perspective, and the strategies to improve their conservation success in animal care centers and in the wild. The type of food used in successful pangolin protection agencies is quite variable in nutritional composition. In the diet of pangolins in the wild, the nutrient profile of different species of termites and ants and even the same species of termites and ants but different types (queens, soldiers, etc.) also displays differences. The crude protein content of some ants is higher than that of other foods, such as eggs, milk, and common cat food. The mineral and vitamin concentrations of ants also exceed many common food items, such as oil, meat, and eggs. However, not much is known about the bioavailability of minerals from ants and termites. Based on comparisons between foods, it is clear that the main difference between diets in the wild and in human care of pangolins is that the latter contains fewer insects and vitamins, such as vitamin E, vitamin A, and vitamin B2, and more carbohydrates and non-protein substances than the former. Although many successful dietary formulae have been developed, the pangolin's nutritional needs are still less well studied. A diet with the nutrient concentrations observed in the wild may add to successful ex situ conservation.

Impacts of eosinophil percentage on prognosis acute type A aortic dissection patients.

BACKGROUND: Eosinophils are pro-inflammatory cells involved in thrombosis and have been proposed as a prognosis marker in acute ischemic stroke and ST-elevation myocardial Infarction. Here, we sought to clarify the prognostic value of eosinophil percentage (EOS%) in patients with acute type A aortic dissection (AAAD). METHODS: We examined 183 consecutive AAAD patients. Based on the optimum cut-off value of EOS% determined by X-tile software, patients were classified into the low EOS% (EOS% ≤ 0.1) and high EOS% groups (EOS% > 0.1). We performed multivariate regression analysis and Kaplan-Meier (KM) survival curves to assess the association between EOS% and mortality. Eosinophil accumulation in aortic dissection intraluminal thrombus was confirmed using hematoxylin-eosin (H&E) staining. An external cohort from Medical Information Mart for Intensive Care IV was performed to validate the results. RESULTS: Relative to surviving patients, those who died during hospitalization had significantly lower EOS% (p = 0.001) but significantly higher WBC (p = 0.002) and neutrophil (p = 0.001) counts. Multivariate regression analysis identified EOS% as an independent predictor of in-hospital and 1-year mortality. KM curves revealed that 1-year cumulative mortality was significantly higher in the low EOS% group, although it was mainly attributed to the higher 30-day mortality. H&E staining revealed massive infiltration of eosinophils in all 20 thrombus specimens. The external validation confirmed that relative to survivors, patients with in-hospital mortality (p = 0.010) had significantly lower EOS%. Moreover, multivariate regression analyses identified that decreased EOS% was independently significantly associated with in-hospital mortality. CONCLUSIONS: Low EOS% is significantly related to increased mortality rates in AAAD patients.

Survival benefit of perioperative chemotherapy for T1-3N0M0 stage esophageal cancer: a SEER database analysis.

BACKGROUND: The effect of perioperative chemotherapy on patients with lymph node-negative esophageal cancer (EC) is controversial. This study explored which EC patients, staged under the T1-3N0M0, would benefit from perioperative chemotherapy. METHODS: Data on patients with diagnosed primary EC were retrieved from Surveillance, Epidemiology and End Results (SEER) database. Propensity score-matched (PSM) method was performed to balance baseline covariates. Multivariate Cox regression analysis and Kaplan-Meier curve were used to assess potential survival difference between patients undergoing surgery plus perioperative chemotherapy (SA + CT) and those undergoing surgery alone (SA). RESULTS: In a total of 2,711 EC patients (T1-3N0M0), 166 patients underwent SA + CT and 2,545 patients received SA. In the multivariable analysis, T stage was significantly related to prognosis of EC patients before and after matching. Subgroup analysis showed that perioperative chemotherapy was associated with poor cancer-specific survival (CSS) for stage T1 patients. There was no effect of perioperative chemotherapy on overall survival (OS) or CSS for T2 patients, whereas a remarkable improvement in OS and CSS was observed for T3 patients. Survival analysis showed that T3 stage EC patients obtained survival benefit from SA + CT. Prognosis in the SA group was significantly better than in the SA + CT group for T1 patients. However, T2 patients showed no significant increase in survival after undergoing SA + CT compared with SA. CONCLUSIONS: T3 patients benefit more from SA + CT. However, perioperative chemotherapy does not present survival benefit to T1-2 patients, and it is an adverse prognostic factor for T1 patients.

Reparative effects of lycium barbarum polysaccharide on mouse ovarian injuries induced by repeated superovulation.

To explore the repair effect of lycium barbarum polysaccharide (LBP) on ovarian injuries induced by repeated superovulation in mice, a model of ovarian injury was established, and ovarian repair was assessed after intragastric administration of LBP. The oocyte quality and blastocyst rates of pronuclear embryos in vitro were observed. The levels of 8-hydroxydeoxyguanosine (8-OHdG) and lipid peroxide (LPO) in ovarian tissue were measured, and ovarian damage was assessed in paraffin sections. The groups with significant injury were selected according to the above observation, mice in the significant injury group were intragastrically administered with LBP (low dose, 25 mg/kg; medium dose, 35 mg/kg; and high dose, 45 mg/kg) for 30 days. The above measurements and anti-Müllerian hormone (AMH) expression were detected in the mouse ovaries and the breeding verification was carried out. Our results showed that repeated superovulation could cause mouse oocyte quality to drop, significant differences started from 4 superovulation events (P < 0.05). The levels of 8-OHdG and LPO in the ovary increased gradually as the number of superovulation events increased, and significant differences were observed after 4-6 superovulations (P < 0.05). The ratios of primordial follicles, primary, tertiary and mature follicles decreased and the ratio of atresia follicles increased as the number of superovulation events increased, especially in 4-6 superovulation groups. Thus, the groups of superovulation 4-6 events were considered as significant injury groups. LBP-medium dose groups significantly improved the number and quantity of oocytes and embryo blastocyst rate (P < 0.05), significantly decreased 8-OHdG and LPO levels in mice ovary (P < 0.05), also improved the ratios of all stages follicles and reduced the rate of atresia follicles, increased the numbers of litter size, live birth, weaning survival, and repaired the expression of AMH in ovary significantly (P < 0.05). In conclusion, the degree of ovarian injury was affected by the number of superovulation. LBP repaired ovarian injuries most likely through scavenging oxidative products 8-OHdG and LPO and increasing AMH protein expression.

Nitrogen-rich covalent organic frameworks as solid-phase extraction adsorbents for separation and enrichment of four disinfection by-products in drinking water.

Disinfection by-products (DBPs) in drinking water can pose a health risk to humans. In this work, a new nitrogen-rich covalent organic frameworks (TpTt-COFs) was synthesized and applied firstly as a novel solid-phase extraction (SPE) trapping media for four ultra-trace levels of DBPs in drinking water samples. Under the optimal conditions, these DBPs were absorbed on a SPE cartridge; then, the DBPs were eluted with the optimized volume of eluent. The concentrated elution was detected and quantified by gas chromatography-mass spectrometry. Low limits of detection (0.0004-0.0063 ng mL-1), wide linearity (0.002-50 µg L-1), good reproducibility (1.54-2.88%) and repeatability (1.28-3.40%) were obtained. This novel method has been successfully applied to the analysis of ultra-trace levels DBPs in real drinking water samples. These accurate experimental results by this method indicated that the novel TpTt-COFs as a SPE trapping material was an attractive option for efficient and effective analysis of ultra-trace levels DBPs in future.

Anaerophilus nitritogenes gen. nov., sp. nov., isolated from salt lake sediment in Xinjiang Province, China.

An obligately anaerobic, nitrate-reducing bacterial strain (MJB2T) was isolated from sediments of saline in Xinjiang province of China. Cells were Gram-stain-positive rods and motile by means of flagella and formed endospores. The novel strain MJB2T was able to grow at 15-37 °C (optimum 28-30 °C), pH 5.8-9.4 (optimum 7.8) and with 1.0-7.0% NaCl (optimum 5.0-6.0%, w/v). Sulfate, sulfite, thiosulfate, elemental sulfur, nitrite and Fe(III) were not used as terminal electron acceptors. Oxidase and catalase reactions were positive. H2S was producted from L-cystine. Complex substrates such as beef extract, peptone and yeast extract can be used as sole energy sources. The DNA G+C content was 29.4 mol%. The major cellular fatty acids (> 10%) were C14:0, C16:1 cis 7 and C16:1 cis 9. The main polar lipids consisted of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, three unidentified amino lipids, one unidentified amino glycolipid, two unidentified glycolipid, one unidentified aminophospholipid and two unidentified lipids. No respiratory quinones were detected. According to phylogenetic analysis based on 16S rRNA gene sequences, strain MJB2T was affiliated to the family Clostridiaceae (order Clostridiales) with highest 16S rRNA gene sequence similarity of 95.3% to Crassaminicella profunda Ra1766HT. Strain MJB2T exhibited 74.9% ANI values to C. profunda Ra1766HT. In silico DNA-DNA relatedness value between strain MJB2T and C. profunda Ra1766HT was 19.5%. The distinct biochemical, chemotaxonomic and phylogenetic differences from the previously described taxa supported that strain MJB2T represents a novel species of a new genus, for which the name Anaerophilus nitritogenes gen. nov., sp. nov. is proposed. The type strain is MJB2T (=KCTC 15800T=MCCC 1K03631T).

MicroRNA­192 acts as a tumor suppressor in colon cancer and simvastatin activates miR­192 to inhibit cancer cell growth.

Colon cancer is one of the most common malignant tumors worldwide. Understanding the underlying molecular mechanisms is crucial for the development of therapeutic strategies for the treatment of patients with colon cancer. In the present study, a novel tumor suppressive microRNA, miR­192, was demonstrated to be markedly downregulated in colon cancer cells compared with normal colon cells. By overexpressing miR­192 in colon cancer HCT­116 cells, the results of the present study revealed that miR­192 inhibits cell proliferation, migration and invasion. Bioinformatics were used to determine the target gene of miR­192 and Ras­related protein Rab­2A (RAB2A) was identified as a downstream target of miR­192. Following the determination of the role of the miR­192­RAB2A pathway in colon cancer, small molecules that may regulate miR­192 were screened and the results demonstrated that simvastatin is an activator of miR­192. Furthermore, simvastatin upregulated miR­192 and inhibited the expression of downstream targets of miR­192, which subsequently led to suppressed proliferation, migration and invasion of colon cancer cells. In conclusion, the present study identified a novel colon cancer cell suppressor, as well as a small­molecule activator of the tumor suppressor miR­192, which may represent a therapeutic strategy for the treatment of patients with colon cancer.

Effects of icariin on ovarian function in d-galactose-induced aging mice.

In this study, effects of icariin (Ica) on were examined in a mouse model of d-galactose (D-gal)-induced ovarian aging. Kunming white mice were divided into three groups: aging group induced with D-gal, experiment group treated with Ica at low (50 mg/kg), middle (100 mg/kg) and high (200 mg/kg) concentrations, and control group with no treatment. Ovarian histomorphology, serum FSH, LH and E2 levels, and reproductive function were compared among the groups. Ovarian expression of Amh, Bax and Bcl-2 was examined by qPCR and western blotting. Our results showed that diameters of secondary and tertiary follicles were significantly reduced in the aging group when compared with control group (P < 0.01), and were restored to normal in Ica 100 and Ica 200 treatment groups. The diameter of atretic follicles was significantly smaller in the aging group compared with control group and Ica 200 treatment group (P < 0.05). The proportion of secondary and atretic follicles was higher in the aging group compared with control group, Ica 100 and 200 treatment groups, whereas the proportion of tertiary and mature follicles was reduced in the aging group versus control, Ica 100 and 200 groups. The aging group lacked mature follicles, whereas Ica treatment induced mature follicle development. Primary and secondary follicles exhibited similar theca cell numbers and theca interna and externa cell layers in all groups examined, whereas theca interna and externa cell layers were decreased and increased, respectively, in tertiary follicles of aging group compared with control and I 200 groups. In the aging group, FSH and LH levels were significantly higher than those in control and Ica 200 groups (P < 0.05), and the E2 level was significantly reduced compared with control (P < 0.01), Ica 200 (P < 0.01), and Ica 100 (P < 0.05) groups. Serum hormone levels were equivalent in the control, Ica 100 and Ica 200 groups. The pregnancy rate was reduced in the aging group compared with other groups. The average litter size per birth, birth litter weight, and weaning weight of litters were all significantly lower in the aging group compared with control, Ica 100 and 200 groups (P < 0.05). The ovarian expression of AMH and Bcl-2 mRNA was significantly reduced in the aging group compared with those in control and Ica-treated groups (P < 0.01). In contrast, Bax expression was significantly higher in the aging group compared with all other groups (P < 0.01), and the Bcl-2/Bax ratio was markedly reduced in aging group compared with control, Ica 100 and 200 groups (P < 0.01), and Ica 50 group (P < 0.05). Ovarian expression of AMH protein was elevated in the Ica 100 group compared with the aging, control and Ica 50 groups (P < 0.01) and Ica 200 group (P < 0.05). Ovarian Bcl-2 protein levels and the Bcl-2/Bax ratio were significantly higher in the Ica 100 group than those in the Ica 50, 200 and aging groups (P < 0.05), and were similar or reduced (P < 0.05), respectively, compared to those in control group. Ovarian Bax expression was similar in each group. These findings suggest that Ica can improve ovarian follicular development, inhibit follicular atresia, decrease FSH and LH levels and increase E2, upregulate ovarian AMH expression and increase the Bcl-2/Bax ratio in aging mice. Therefore, Ica can partially restore ovarian function of aging mice and enhance their fertility. Optimal reproductive effects were obtained with the Ica 100 group.

Mammalian target of rapamycin/eukaryotic initiation factor 4F pathway regulates follicle growth and development of theca cells in mice.

The aim of the present study was to clarify the roles of the mammalian target of rapamycin (mTOR) signalling pathway in follicular growth and development of thecal cells. Using in vivo-grown and in vitro-cultured ovaries, histological changes were evaluated using haematoxylin and eosin (HE) staining. Differentially expressed genes (DEGs) from 0 day post partum (d.p.p.) to 8 d.p.p. ovaries were screened by microarray and verified by quantitative real-time polymerase chain reaction. Forty-two DEGs related to cell proliferation and differentiation were screened out, with most DEGs being related to the to mTOR signalling pathway. Then, 3 d.p.p. ovaries were retrieved and used to verify the role of mTOR signalling in follicle and thecal cell development using its activators (Ras homologue enriched in brain (Rheb) and GTP) and inhibitor (rapamycin). The development of follicles and thecal cells was significantly impaired in ovaries cultured in vitro Day 3 to Day 8. In in vitro-cultured ovaries, Rheb and GTP (is 100ngmL-1 Rheb and 500ngmL-1 GTP for 48h) significantly increased follicle diameter, the percentage of primary and secondary follicles and the umber of thecal cells, and upregulated expression of mTOR, phosphorylated eukaryotic translation initiation factor 4E-binding protein 1 (4EBP1), eukaryotic initiation factor (eIF) 4F and cytochrome P450, family 17, subfamily A, polypeptide 1 (CYP17A1). Rapamycin (10nM rapamycin for 24h) had opposite effects to those of Rheb and GTP, and partly abrogated (significant) the effects of Rheb and GTP when added to the culture in combination with these drugs. Thus, mTOR signalling plays an important role in follicle growth and thecal cell development.

[In vitro safety evaluation study of Angong Niuhuang Wan].

To study a vitro extraction method to determine soluble mercury and mercury species in Angong Niuhuang Wan and investigate a vitro safety evaluation method, the best extraction scheme was determined after a great deal of conditioning experiments focusing on how the solvent, purification, duration of extraction and purification etc impact on mercury extraction. Soluble mercury was determined by inductively coupled plasma mass spectrometry and mercury species were determined by high performance liquid chromatography/inductively coupled plasma mass spectrometry. Result show that the best extraction method of soluble mercury and its species was ultrasonic extraction in artificial intestinal juice at 37 °C for 2 hours, letting it stand for 20 hours and taking the supermatant. The method was reproducible, which could simulate the human body environment to maximum extent. Methyl mercury, ethyl mercury and Hg2+ were not found in the extracts of Angong Niuhuang, although the content of soluble mercury was high. It Was concluded that the method could be applied to the vitro extraction and determination of soluble mercury and mercury species in Chinese traditional medicines containing cinnabar. Methyl mercury, ethyl mercury and Hg2+ could be taken as the targets of in vitro safety evaluation of Angong Niuhuang.

Expression of IER3 in primary hepatocarcinoma: correlation with clinicopathological parameters.

BACKGROUND: Studies indicate the immediate early response gene 3 (IER3) is involved in many biological processes. Recently, it was discovered that IER3 plays an important role in tumorigenesis and tumor progression. Thus it may be a valuable biomarker in tumor. This study was designed to investigate the expression status of IER3 in primary hepatocarcinoma (PHC) and correlation with clinicopathological parameters. MATERIALS AND METHODS: Real-time PCR was performed to evaluate the expression levels of IER3 in 62 pathologically diagnosed human PHC specimens. RESULTS: A statistically significant association was disclosed between the expression of IER3 and P53 mutant protein (short for P53), Ki-67, EGFR and the biggest diameter, differentiation grade of tumor. CONCLUSIONS: This work is the first to shed light on the potential clinical usefulness of IER3, as an efficient tumor biomarker in PHC.

Bone marrow mesenchymal stem cells protect against retinal ganglion cell loss in aged rats with glaucoma.

Glaucoma is a common eye disease in the aged population and has severe consequences. The present study examined the therapeutic effects of bone marrow mesenchymal stem cell (BMSC) transplantation in preventing loss of visual function in aged rats with glaucoma caused by laser-induced ocular hypertension. We found that BMSCs promoted survival of retinal ganglion cells in the transplanted eye as compared with the control eye. Further, in swimming tests guided by visual cues, the rats with a BMSC transplant performed significantly better. We believe that BMSC transplantation therapy is effective in treating aged rats with glaucoma.

Effects of exposure to low-level lead on spatial learning and memory and the expression of mGluR1, NMDA receptor in different developmental stages of rats.

The effect of different periods of lead exposure on deficits of learning and memory is still unclear. In this study, we conduct in vivo experiment to investigate the critical stages when lead induced neurotoxicity in rats and its underlying mechanisms in some critical stages. Rats were exposed to 0.2% mg/ml lead acetate solution via drinking water during gestation, lactation and ablactation periods. Behavior deficits were found in gestation and lactation. N-Methyl-d-aspartate (NMDA) receptor subunit 2A (NR2A) increased during gestation both in hippocampus and cerebral cortex compared to the control group; in all treatment groups NR2B decreased in hippocampus and in cerebral cortex during the lactation period. Meanwhile, in hippocampus metabotropic glutamate receptor 1 (mGluR1) decreased during gestation and lactation periods but increased during the ablactation period. These observations suggest that exposure to lead in gestation and lactation periods could cause neurobehavioral deficits which extend to adulthood, and lactation was a more sensitive period for lead exposure. Furthermore, the abnormal expression of NMDA receptor 2 (NMDAR 2) subunits and mGluR1 are likely to be associated with the impairment.

[Granulocytic sarcoma: a clinical and pathologic analysis of ten cases].

OBJECTIVE: To investigate the clinical and pathological features, differential diagnosis of granulocytic sarcoma. METHODS: The clinical manifestations, histopathological features, immunohistochemistry, treatment and prognosis were analyzed retrospectively in 10 cases of granulocytic sarcoma. RESULTS: The age of patients ranged from 10 to 56 years (means = 35.8 years). The male-to-female ratio was 1.5:1. Histologically, the malignant cells of granulocytic sarcoma grew in a diffuse pattern. The cytoplasm was scanty, with eosinophilic fine granularity in some cells. The nuclei were round or focally irregular, and had finely dispersed chromatin. The mitotic figures were visible. Immunohistochemical stains for MPO, CD43, CD117, CD34 and CD99 were positive. CONCLUSIONS: Granulocytic sarcoma can occur in patients of all ages with a male predominance. The diagnosis of granulocytic sarcoma is assisted by the cytochemical stain for naphthol-ASD-chloroacetate esterase and/or immunophenotypic analyses for MPO, CD43, CD117, CD34, CD99. These stains aid in the distinction of granulocytic sarcoma from: lymphoblastic lymphoma, Burkitt lymphoma, diffuse large B-cell lymphoma, small round cell tumours, particularly in children, and blastic plasmacytoid dendritic cell neoplasm.

Characteristics of the macula in amblyopic eyes by optical coherence tomography.

AIM: To test the hypothesis that amblyopic neuroretina may have an altered thickness when compared to the normal. METHODS: Twenty-five amblyopic, young patients between the ages of 7 and 11 years old were studied. The interested neuroretina areas are defined into 10 sub-regions according to superior-inferior, nasal-temoral, and peri-para axis, which cross the fovela structure. The thicknesses of ten, defined macular regions were separately measured by optical coherence tomography (OCT) and analyzed by t-test. RESULTS: The average thickness of neuroretina in the exact foveola of the amblyopic eyes is larger than that of normal eyes (P<0.05), but the other nine regions have no significant difference. Interestingly, in both the normal and amblyopic eyes, the temporal area looks thinner than other quadrants (P<0.05). CONCLUSION: Thickness alteration may be associated with amblyopic disorders in young patients. Studying a larger volume of subjects of similar age is required to confirm this observation.

Time-course of changes to nitric oxide signaling pathways in form-deprivation myopia in guinea pigs.

The aim of this study was to investigate the time-course change of nitric oxide synthase (NOS) activity and cyclic GMP (cGMP) concentration in the posterior retina, choroid and sclera after differing periods of form-deprivation in guinea pigs. Three groups of guinea pigs were subjected to monocular FD for 7, 14 or 21 days. NOS activity and cGMP concentrations in ocular tissues of FD eyes and control eyes were analyzed by radioimmunoassay. The presence of NOS isoforms was detected by immunohistochemistry. Guinea pigs presented with considerable myopia after 14 days of FD. Retinal NOS activity in the FD group was lower than in the control group after 7 days of FD and was higher than in the control group after 14 and 21 days of FD. The choroidal and scleral NOS activities in the FD groups were higher than in the control groups after 21 days. The cGMP concentrations in the FD groups were higher than in the control groups at 21 days of the retinal, choroidal, and scleral tissues. Furthermore, the retinal cGMP concentration in the FD group was also significantly elevated at 14 days relative to the control group. We detected expression of three NOS isoforms in guinea pig ocular tissues. Our main observations were a change in NOS activity and an up-regulation in cGMP concentrations in posterior ocular tissues during the development of myopia. The function of elevated NOS activity may be mediated by cGMP.

[Expression of 5 muscarinic receptor subtypes in the scleral tissue of immature guinea pigs].

OBJECTIVE: To investigate the expression of 5 muscarinic receptor subtypes in the scleral tissue of immature guinea pigs. METHODS: The scleral tissue was collected from six 2-week-old pigmented guinea pigs to determine mRNA expressions of the muscarinic receptors with RT-PCR. Immunofluorescence was used to observe the protein expressions of the 5 muscarinic receptor subtypes. RESULTS: The mRNAs of the 5 muscarinic receptor subtypes were all detected in the scleral tissue, and the mRNA expression was the highest for M1 subtype. Green fluorescence of M1 to M5 subtypes surrounding the fibroblast nuclei were found in the scleral matrix using laser confocal microscopy. CONCLUSION: Five muscarinic receptor subtypes are present in the scleral tissues of immature guinea pigs, indicating the involvement of the muscarinic receptors in eye growth regulation.

Changes of nitric oxide synthase and cyclic guanosine mono-phosphate in form deprivation myopia in guinea pigs.

BACKGROUND: The form deprivation (FD) reduces spatial contrasts and induces myopia. Nitric oxide and cyclic guanosine monophosphate (cGMP) are involved in visual signal transmission. This study investigated changes in nitric oxide synthase (NOS) activity and cGMP concentration in ocular tissues in acute and chronic form deprivation myopia. METHODS: Guinea pigs had one eye covered by translucent glass for 7, 14 or 21 days. Untreated litter mates were used as controls. NOS activity and cGMP concentrations in the retinal, choroidal and scleral tissues of FD eyes and control eyes were analyzed by radioimmunoassay after various durations of FD. The expression of NOS subtypes was identified by immunohistochemistry. RESULTS: Myopia was successfully induced in FD eyes after 14 days. Compared with control groups, the retinal NOS activity and cGMP concentrations in the FD eyes significantly increased after 14 and 21 days while the retinal NOS activity in the FD eyes was transiently suppressed by 7 days of FD. The NOS activity and cGMP concentrations of choroid and sclera in the FD eyes were higher than in the control groups at 21 days. The three isoenzymes of nitric oxide synthase were detected in the ocular tissues of guinea pigs. CONCLUSIONS: The NOS activity and cGMP concentrations were upregulated after chronic FD and the retinal NOS activity was transiently suppressed at acute FD. The function of elevated NOS activity may be mediated by cGMP.