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Yong Tang

Publications and source records attributed to Yong Tang.

82 records · Page 5Linked to original sources
PubMed2002

Wittig-type olefination catalyzed by PEG-telluride.

Soluble poly(ethylene glycol) (PEG)-supported telluride 2 was designed and synthesized for catalytic Wittig-type reactions. It was found that the catalytic loading could be reduced from 20 to 2 mol % by the introduction of PEG (even to 0.5 mol % when some telluride salts were used as the catalyst). Under the catalytic reaction conditions, a wide variety of aldehydes with different structures could react with bromoacetate to afford beta-substituted or alpha,beta-disubstituted unsaturated esters in high yields with excellent E-stereoselectivity. The modified process, by using sodium bisulfite instead of triphenyl phosphite, represented a very simple product isolation procedure. The roles of PEG for promoting the ylide formation and stabilizing the catalytic species were disclosed. The mechanism was also studied.

Journal Article↗
PubMed2002

A novel chiral sulfonium yilde: highly enantioselective synthesis of vinylcyclopropanes.

A newly designed chiral sulfonium allylide, generated in situ from the corresponding sulfonium salt in the presence of KOBu(t), reacted with alpha,beta-unsaturated esters, ketones, amides, and nitriles to afford trans-2-silylvinyl-trans-3-substituted cyclopropyl esters, ketones, amides, and nitriles with outstanding diastereoselectivity and excellent enantioselectivity in good to high yields. A mechanistic rationale is proposed.

Cyclopropanes↗
PubMed2002

Application of unbiased stereology on archival human temporal bone.

OBJECTIVE: The current report presents unbiased stereological sampling and counting strategies for estimating the total number of neurons in the spiral and vestibular ganglia of the archival human temporal bone. STUDY DESIGN: Application of unbiased stereology using archival human temporal specimens. Observational study. METHODS: The practical sampling and counting strategies for estimating the number of neurons are presented. To illustrate the method described, the total number of neurons in spiral and vestibular ganglia from archival human temporal bone was estimated. RESULTS: The study found, on average, 41,643 (coefficient of variation = 0.12) spiral ganglion neurons in the subjects with an average age of 35.6 years (age range, 22-60 y) and, on average, 27,635 (coefficient of variation = 0.10) vestibular ganglion neurons in the subjects with an average age of 28.6 years (age range, 2-58 y). CONCLUSIONS: The total number of primary auditory and vestibular ganglion neurons from the current study differs significantly from the previously published data using assumption-based methods. The unbiased stereological technique presented in the current report thus would be invaluable for future studies on such specimens, including the study of the changes of neurons during aging and various pathological conditions.

Cell Count↗
PubMed2002

[Experimental study on enhancement of tissue expansion with papaverine cream].

OBJECTIVE: To evaluate the effect of external use of papaverine cream on enhancement of tissue expansion. METHODS: 8 mini pigs were randomly divided into 4 groups. During inflation, papaverine was given externally in group A, through a delivery system in group B, though intramuscular injection in group C. Papaverine was not given in group D. The time of inflation, the expansion rate, the surviving length of expanded flaps and the papaverine concentration in the fibrous capsule in each group were examined. Histologic and electroscope examinations of the expanded tissue were made. RESULTS: The average inflation time was 28.9 +/- 4.5 days in group A, 34.0 +/- 2.6 days in group B, 37.6 +/- 4.8 days in group C and 38.5 +/- 3.5 days in group D. There was significant difference between each group(P < 0.05). The average surviving length of expanded flaps in group A was 13.67 +/- 1.28 cm, 11.07 +/- 0.88 cm in group B, 10.79 +/- 0.49 cm in group C, and 9.49 +/- 0.77 cm in group D. There was significant difference between each group (P < 0.01). Histologic examinations of the expanded tissue suggested that there were no significant differences in thickness of epidermis, derma and fibrous capsule among the four groups. Electroscope examinations of the myofibroblast in fibrous capsule showed that there were smaller nuclei, fewer microfilaments and fewer mitochondrias and rougher endoplastic reticulume in group A than those in other groups. The concentration of papaverine in fibrous capsule of group A was 3.5 +/- 1.2 micrograms/g. Papaverine was detected neither in the skin of other groups nor in the blood of all groups. CONCLUSIONS: 1. Papaverine cream can permeate through skin and maintain high concentration and continuous effect in local tissue. 2. External use of papaverine cream can inhabit the function of myofibroblast in fibrous capsule, increase inflation rate, accelerate expansion process, and improve microcirculation of the expanded skin with a result of prolongation of surviving length of expanded flaps. 3. The technique of enhancing tissue expansion with external use of papaverine has the advantages of convenient delivery, cheapness, no more injury and infection, and no side effects etc. It is a safe, effective, simple, and reliable method for accelerating tissue expansion.

Animals↗
PubMed2002

Influences of olfactory ensheathing cells transplantation on axonal regeneration in spinal cord of adult rats.

OBJECTIVE: To observe whether olfactory ensheathing cells could be used to promote axonal regeneration in a spontaneously nonregenerating system. METHODS: After laminectomy at the lower thoracic level, the spinal cords of adult rats were exposed and completely transected at T10. A suspension of ensheathing cells was injected into the lesion site in 12 adult rats, and control D/F-12 (1:1 mixture of DMEM and Ham's F-12) was injected in 12 adult rats. Six weeks and ten weeks after cell transplantation, the rats were evaluated by climbing test and motor evoked potentials (MEPs) monitoring. The samples were procured and studied with histologicl and immunohistochemical methods. RESULTS: At the 6th week after cell transplantation, all the rats in both the transplanted and control groups were paraplegic and the MEPs could not be recorded. At the 10th week after cell transplantation, of 7 rats in the control group, 2 rats had muscles' contraction of the lower extremities, 2 rats had hips and/or knees' active movement; and 5 rats' MEPs could be recorded in the hind limbs in the transplanted group (n=7). None of the rats in the control group had functional improvement and no MEPs recorded (n=7). Numerous regenerating axons were observed through the transplantation and continued to regenerate into the denervated host tract. Cell labelling using anti-Myelin Basic Protein (MBP) and anti-Nerve Growth Factor Receptor (anti-NGFR) indicated that the regenerated axons were derived from the appropriate neuronal source and that donor cells migrated into the denervated host tract. But axonal degeneration existed and regenerating axons were not observed within the spinal cords of the adult rats with only D/F-12 injection. CONCLUSIONS: The axonal regeneration in the transected adult rat spinal cord is possible after ensheathing cells transplantation.

Animals↗
PubMed2002

[Surgical depilation in low hairline aurical reconstruction].

OBJECTIVE: Low hairline is one of the most troublesome problem in auricle reconstruction. There was no satisfactory way to manage the problem. This article discuss surgical depilation to deal with this problem and reconstructed auricle. METHODS: According to the degree of the low hairline, Postaurical scalp was expanded and part of the lower follicles within the dermal were removed, or postaurical scalp that part of lower follicles and dermal had been removed was expanded and covered skeleton of ear with this expanded skin to reconstructed auricle. RESULTS: Auricles were reconstructed with this method in 152 lowhairline microtial cases, the result was very satisfactory. CONCLUSION: This procedure is an effective way to deal with low hairline in reconstructing auricle.

Adolescent↗
PubMed2002

[Determination of papaverine hydrochloride in skin and blood and the drug contents in pig skin].

OBJECTIVE: To explore the application of ultraviolet spectrophotometer in determining papaverine hydrochloride content in blood and skin and to determine the intradermal content after local external application of papaverine hydrochloride. METHODS: Phosphate buffer solution (pH = 10, ionic strength = 0.4) was added into the blood or ground skin tissue containing papaverine hydrochloride, and papaverine hydrochloride was extracted with chloroform-hexane mixture (ratio:2:3). After oscillation and centrifugation, partial organic phase was retrieved and dried in 60 degrees C water bath. The dried product was dissolved in 1 mol/L HCl and then underwent filtration through 0.2 micron membrane. The ultraviolet apectrophotometry was applied to determine the content of papaverine hydrochloride in the filtrate. 2% papaverine hydrochloride cream was applied on pig's skin and skin specimen was retrieved at given time to determine the papaverine hydrochloride content in skin tissue with ultraviolet spectrophotometry. RESULTS: The absorbance spectrum of the extract was typical of that of papaverine hydrochloride, with no miscellaneous peak. The extractive rate of papaverine hydrochloride in blood of was more than 92% and that in skin tissue more than 87%. Eight hours after external application of 2% papaverine hydrochloride cream on pig skin, the content of papaverine hydrochloride in skin tissue was more than 90 micrograms/g, significantly higher than the effective concentration of papaverine hydrochloride. CONCLUSIONS: Ultraviolet spectrophotometry is a simple, economical and reliable method for the determination of papaverine hydrochloride content in blood and skin tissue, with good reproducibility and sensibility. External application of papaverine hydrocholine cream can provide efficient permeation and drug concentration in the skin.

Animals↗
PubMed2002

[An experimental study on repair of laryngeal cartilage defect with the bone morphogenetic protein composite].

OBJECTIVE: To study the effects of the bone matrix gelatin and composite of bone morphogenetic protein and fibrin glue (BMP-FG) on the repair of thyroid cartilage defect. METHOD: Full-thickness defects measuring 0.4 cm x 0.4 cm were created in four sections in thyroid cartilages of 20 adult dogs. The defects were divided into 4 groups by the sections they in. Group A was empty group, without implant; Group B were repaired by implanted with hydroxylapatite; Group C with bone matrix gelatin (containing BMP); Group D with bone morphogenetic protein-fibrin glue composite. The animals were killed separately at 2, 4, 12 weeks after operation. The effects of repair were analyzed by routine histological examination and electron microscope. RESULT: In the BMP-FG implanted group, the result showed complete absorption of the implant and substitution by new-formed cartilage and bone. The defects in the BMG group regenerated less cartilage and bone, the inflammation was sever. The gross appearance and histological features of HA group were similar to the empty group. CONCLUSION: Both BMP-FG and BMG can induce cartilage and bone regeneration to repair the defect of thyroid cartilage. BMP-FG has a better effect.

Animals↗
PubMedDate not supplied

Correlation of serum VEGF levels with clinical stage, therapy efficacy, tumor metastasis and patient survival in ovarian cancer.

Vascular endothelial growth factor (VEGF) has been shown to play an important role in tumor growth and progression. However, the clinical implications of VEGF expression in ovarian tumors are not fully understood. We therefore investigated the serum level of VEGF in patients with ovarian tumors and explored the potential use of VEGF as a tumor marker for diagnosis, treatment and prognosis of human ovarian cancer. The serum VEGF (sVEGF) levels in 120 patients with ovarian carcinoma, 25 patients with benign ovarian tumor and 90 healthy female blood donors were measured by an enzyme-linked immunosorbent assay in this study. We also determined the levels of sVEGF in patients with epithelial ovarian cancer before and after surgery. Our results showed that: (i) ovarian cancer patients had significantly higher levels of sVEGF compared to those of patients with benign ovarian tumor or those of healthy individuals. As a cut-off at 100 pg/ml, the sensitivity and specificity of sVEGF levels for diagnosing ovarian carcinoma were 77.1% and 87%, respectively. (ii) sVEGF levels were markedly elevated in patients with advanced stage or poorly-differentiated ovarian cancer, as well as in those with more ascites (>500 ml), as compared to patients with early stage and well-differentiated ovarian cancer, or those with less ascites (<500 ml). However, there was no significant difference in sVEGF levels among different pathological subtypes of ovarian carcinoma. (iii) The post-operative sVEGF levels were significantly lower than the pre-operative sVEGF levels. (iv) We measured significantly higher levels of sVEGF in patients with metastasis as compared to patients lacking metastasis. Lastly (v) the average survival-time in patients with higher levels of sVEGF (>100 pg/ml) was 28 months, while the average survival-time in patients with lower levels of sVEGF (<100 pg/ml) was 35 months, indicating that the elevations in sVEGF level are correlated with patient survival and tumor metastasis in ovarian carcinoma. These data suggest that VEGF may be a useful serological biomarker for clinical diagnosis and prognosis of ovarian cancer, for follow-up of ovarian tumor metastasis and for monitoring the efficacy of therapy in patients with ovarian carcinomas.

Adult↗