Biomedical subjects
Publications and source records attributed to F Gao.
From the leaves and the flowers of Helianthus glaucophyllus and Helianthus microcephalus, three new guaianolides were isolated. H. microcephalus afforded another two new guaianolides, the highly unsaturated guaianolide, the flavane, the flavone, and three flavonols. Structures of all the compounds were determined by spectral analysis.
Reference adducts formed by reaction of deoxyribonucleosides with the ultimate carcinogenic forms of benzo[a]pyrene (BP), BP radical cation and BP diol epoxide, are essential for identifying the structures of adducts formed in biological systems. Electrochemical oxidation of BP in the presence of dG or dA produces adducts from BP radical cation. When 8 equiv of charge are consumed, four adducts are formed with dG: 7-(BP-6-yl)Gua, 8-(BP-6-yl)Gua, N2-(BP-6-yl)dG and 3-(BP-6-yl)dG. With 2 equiv of charge, however, only 7-(BP-6-yl)Gua and 8-(BP-6-yl)dG (BP-6-C8dG) are formed. Anodic oxidation of BP-6-C8dG affords 8-(BP-6-yl)Gua. Anodic oxidation of BP in the presence of dA produces 7-(BP-6-yl)Ade. Reaction of BP diol epoxide with dG yields 10-(guanin-7-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydroBP, whereas reaction with dA affords three adducts, 10-(adenin-7-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydroBP and two isomers of 10-(deoxyadenosin-N6-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydroBP . On the basis of comparative kinetic studies among adducts of aromatic hydrocarbons and dG or G, only BP-6-C8dG easily loses the sugar moiety, providing a basis for a mechanism of hydrolysis of the glycosidic bond.
OBJECTIVE: To investigate the utility of lower contrast medium doses for the detection and conspicuity of acoustic schwannomas. MATERIALS AND METHODS: The L/B (L, lesion; B, background) ratios or lesion contrast of 17 pathologically proven acoustic schwannomas studied with a standard dose (0.1 mmol/kg) of gadopentetate dimeglumine was measured. In addition, 22 patients with acoustic schwannomas were studied prospectively with fractional doses using the incremental dose technique. Each patient received an initial bolus injection of one-eight the standard dose (0.0125 mmol/kg) followed by an injection of one-eighth, one-fourth, and one-half the standard dose at 5 min intervals to achieve a cumulative dose of one-fourth, one-half and full dose, respectively. Imaging was performed immediately after each injection. RESULTS: Standard dose--The L/B ratios of pathologically proven acoustic schwannomas to mastoid air cells ranged from 14.8 to 41.2 (mean +/- SEM, 28.0 +/- 1.95), which were approximately 17 times more than those of intraparenchymal lesions. Fractional cumulative dose--Qualitative visual analysis demonstrated that all acoustic schwannomas showed apparent enhancement at one-fourth dose. Intense enhancement was noted at one-half and full dose. Quantitative analysis demonstrated the mean L/B ratios between the acoustic schwannomas and mastoid air cells of the precontrast and one-eighth, one-fourth, one-half, and full dose studies were 8.33 +/- 0.52, 11.21 +/- 0.75, 13.02 +/- 0.83, 15.38 +/- 0.98, and 18.03 +/- 1.36, respectively. CONCLUSION: The L/B ratios or lesion contrast of acoustic schwannomas at various fractional contrast medium doses was significantly higher compared with that of intraparenchymal lesions. Thus, the standard contrast medium dose may not be necessary for detection of acoustic schwannomas, and a fractional dose may be sufficient. Although the optimal fractional dose remains to be determined, one-half of the standard dose (0.05 mmol/kg) appears to be sufficient because of intense enhancement at this dose.
This study develops a percutaneous optical imaging system for tracking fluorescent reporter gene expression in vasculatures. We build a percutaneous optical imaging system that primarily comprised a 1.5-mm, semi-rigid, two-port optical probe. The performance of the optical probe is first tested in vitro with cell phantoms, and then the feasibility of the percutaneous optical imaging system is validated in vivo in eight femoral artery segments of two pigs. The green fluorescent protein (GFP) gene is locally delivered into four arterial segments, while saline is delivered to the four contralateral arterial segments as controls. The targeted arteries are localized using color Doppler, and thereafter the optical probe is positioned to the target arterial segments under ultrasound guidance. Optical imaging captures are obtained using different exposure times from 10 to 60 s. Subsequently, the GFP- and saline-targeted arteries are harvested for fluorescent microscopy confirmation. The percutaneous optical probe is successfully positioned at a distance approximately 2 mm from the targets in all eight arteries. The in-vivo imaging shows higher average signal intensity in GFP-treated arteries than in saline-treated arteries. This study demonstrates the potential using the percutaneous optical imaging system to monitor, in vivo, reporter gene expression from vasculatures.
The effects of aging on DNA, RNA and protein synthesis in adrenal gland cortical cells and testicular Leydig cells of ddY mice at various ages (from prenatal day 19 to postnatal days 1, 3, 7, 14, months 1 and 6 and 1 and 2 years after birth) were examined using light and electron microscopic (EM) radioautography after labeling with [3H]-thymidine, [3H]-uridine and [3H]-leucine. The percentage of the labeled cells in the adrenal glands after [3H]-thymidine injection was greatest in the zona glomerulosa of the cortex and the medulla on embryonic day 19, in the zona fasciculata and zona reticularis of the cortex on postnatal day 1 and gradually decreased with aging. EM radioautography revealed that well developed cell organelles such as smooth surfaced endoplasmic reticulum, Golgi apparatus, mitochondria with tubular cristae and lipid droplets were more frequently observed in the cytoplasm of unlabeled cells as compared to cells labeled with [3H]-thymidine in the three zones of the cortex. The effects of aging on RNA synthesis in adrenal glands after [3H]-uridine injection revealed that all types of cells of the adrenal gland were labeled. In each cell, silver grains were localized over the nuclei and cytoplasm and were more dense in the nuclei than the cytoplasm. Grain counts were highest in the cortex and medulla on fetal day 19 and then gradually decreased with aging from postnatal day 14 to 1 year after birth. In the cortex, the number of silver grains was higher in the zona glomerulosa than in the other zones from fetal day 19 to 1 year and grain counts were higher in the medulla in the embryonic stage as compared to the postnatal stages. However, the number of labeled mitochondria and the mitochondrial labeling index increased with aging. The [3H]-thymidine labeling index in the Leydig cells of the testis was low at embryonic and early postnatal stages, increased slightly at 6 months and reached a peak at 9 months which was maintained at a relatively high level in senescence. The number of the silver grains over the nuclei and cytoplasm of Leydig cells due to [3H]-uridine labeling was observed from embryonic day 19 and increased from month 3 onwards. From adult to senescence, [3H]-uridine incorporation was maintained at high levels in the nuclei and was relatively low in the cytoplasm. The effects of aging on [3H]-leucine incorporation in Leydig cells were also examined. The labeling indices between embryonic and early postnatal stages showed no obvious differences although the number of the silver grains in both cytoplasm and nucleus increased from 6 months onwards and was maintained at high levels until senescence. From these results, it was concluded that the effects of aging on DNA, RNA and protein synthesis in steroid secreting cells such as adrenal gland cortical cells and testicular Leydig cells of mice correlated with the hormonal changes observed with aging.
The results of immunohistochemical expression of p53 protein in 106 invasive breast cancers were correlated with conventional pathologic prognostic parameters. Archival formalin-fixed, paraffin-embedded tissue sections of these cases were stained with a monoclonal antibody (Ab-2), raised against p53 protein using a peroxidase-labelled streptavidin biotin kit. Fifty-six (53%) showed positive nuclear staining; 31 were considered weakly, 21 moderately and 4 strongly positive. Forty-three (77%) of these positive cases stained less than 50% of the tumor cells, with a significant association between intensity and proportion of nuclei stained (p<0. 05). p53 staining also correlated with histologic grade (p<0.005) but not with tumor size nor clinical stage (p>0.05). The follow-up data did not reveal any statistically significant survival advantage for patients with p53 negative tumors.
Methotrexate (MTX) treatment causes the damage of the small intestine, resulting in malabsorption. The aim of this study was to investigate the effect of prostaglandins (PGs), prostaglandin E1 (PGE1) and prostaglandin I2 (PGI2) analogues, on the MTX-induced damage of rat small intestine by examining the permeability of the small intestinal epithelium. The rats were treated as follows: MTX (15 mg/kg/day), MTX and PGE1/PGI2 analogues (0.5 and 5 micrograms/kg/twice a day), PGE1/PGI2 analogues alone, and sterile saline (control). All drugs were given orally for 5 days. The intestinal permeability of fluorescein isothiocyanate labeled dextran with average molecular mass 4.4 KDa (FD-4) was examined to evaluate the dysfunction of the small intestine by the in vitro everted small intestine technique. The permeation clearance of FD-4 obtained from the in vitro experiment of the MTX-treated rats increased remarkably, but that of the MTX and PGE1/PGI2 analogue-treated rats was significantly lower than that of the MTX-treated rats. These results indicated that PGE1 or PGI2 analogues possibly alleviated the MTX-induced damage of the small intestine of rats.
Administration of methotrexate to rats sometimes induces small intestinal damage. A synthetic analog of prostaglandin E1, OP-1206 [17S,20-dimethyl-trans-delta2-prostaglandin E1] may possibly provide therapeutic benefits to help recovery from such small intestinal damage. The purpose of this study was to evaluate the effect of OP-1206 on methotrexate-induced small intestinal damage in rats. Methotrexate (15 mg/kg body weight) was orally administered to rats once daily for 5 days. OP-1206 (0.5 microg/kg body weight) was orally administered to rats twice a day for 5 days and on the 6th day the small intestine of the rats were examined histologically and biochemically. The methotrexate treatment of rats caused a severe histological change in the small intestinal mucosa, whereas the treatment combined of OP-1206 with methotrexate showed similar histological features of the small intestinal mucosa as that of the control rats. On the other hand, an acute intestinal inflammation was evaluated by determining myeloperoxidase activity. The myeloperoxidase activity in the small intestinal mucosa of the methotrexate-treated rats increased remarkably, whereas that of the methotrexate and OP-1206-treated rats was significantly lower than that of the methotrexate-treated rats. Thus, it was shown histologically and biochemically that OP-1206 was effective in protecting the small intestine from methotrexate-induced damage.
The DNA synthesis of mouse retina from the 19th prenatal day through 12 months postnatal has been studied by light microscopic radioautography after the injection of tritiated thymidine. A peak of the labeling index after incorporation of tritiated thymidine was found at fetal day 19. The labelled cells decreased gradually with the developing of the eye from the first postnatal day and were completely disappeared in two weeks after birth. The data also indicated obvious regional differences of the incorporation of tritiated thymidine during the periods of the retina development. The labeling index was the greatest in the anterior region compared to the equator region and the posterior region in the same group of age. The average number of the silver grains in labelled nucleus lead to a decrease with the development of the retina after birth, but there was no significant regional differences found in the same group of age. The data shown from this study suggest that the cell differentiation in mouse retina proceed from posterior to anterior region.
The tensile bond strengths of Comspan (a conventional resin used with composite-bonded prostheses) and Panavia EX (a newer adhesive bonding material) to different types of amalgam were determined. The results were compared with the tensile bond strengths of these resins to etched bovine enamel and properly prepared Rexillium III. The results showed that all of the resin-amalgam bond strengths were statistically less than those of bonding resin to etched bovine enamel or Rexillium III. Coverage of existing amalgam restorations by the metal framework with etched-metal resin-bonded retainers is contraindicated when using either the conventional bonding agent or the new adhesive bonding material, Panavia EX.