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Biomedical subjects

Y F Zhao

Publications and source records attributed to Y F Zhao.

At least 19 recordsLinked to original sources

Facile synthesis of optically pure (S)-3-p-hydroxyphenyllactic acid derivatives.

Optically pure (S)-3-p-hydroxyphenyllactic acid derivatives are important intermediates of peroxisome proliferator-activated receptor alpha/gamma dual agonists and heteropeptides. Many efforts have been made for synthesis of those intermediates, but there exist some flaws yet. We observed that dielectric constants of organic solvents drastically affected diazotization of O-benzyl-L-tyrosine. Optically pure (S)-3-p-benzyloxyphenyllactic acid was obtained by simple recrystallization when DMF or DMSO of higher dielectric constant was used as a co-solvent in diazotization of O-benzyl-L-tyrosine. It was easily turned into various optically pure (S)-3-p-hydroxyphenyllactic acid derivatives.

Molecular Conformation↗

Synthesis, characteristics and biological activity of pentacoordinated spirophosphoranes derived from amino acids.

The reactions of phosphorus trichloride with various amino acids afford the pentacoordinated spirophosphoranes. The reaction procedures were traced by (31)P NMR spectra techniques. A new crystal structure of alanine derivative was characterized, which is a slightly distorted TBP structure. Besides, this kind of spirophosphoranes are potent inhibitors to tyrosinase.

Amino Acids↗

One pot conjugation of the polypeptides directed by phosphorus oxychloride.

A series of homopeptides and their conjugates were synthesized in one pot reaction in the presence of phosphorus oxychloride and the conjugate yield was structurally dependent. Menthol and benzylamine conjugated to the homopeptides quantitatively. Homopeptides when treated with diisopropyloxyphosphite (DIPPH) and NaClO yield the corresponding N-phosphoryl peptides. Electrospray ionization-mass spectrometry (ESI-MS)/MS was used to study the structure of peptide conjugates. This paper reports a simple method to synthesize the homopeptides and their conjugate derivatives and the fact that phosphoryl peptides could also be obtained by one pot reaction.

Benzylamines↗

N-phosphoryl amino acids and biomolecular origins.

The possible role of phosphoryl amino acids for biomolecular origins is briefly reviewed. Peptide formation, ester formation, ester exchange on phosphorus and N to O migration occurred when the N-phosphoryl amino acid was incubated at room temperature. Short nucleotides and peptides were formed when nucleoside was reacted with N-phosphoryl amino acid at room temperature. Serine and threonine residues in their conjugate with different nucleosides (mediated with phosphorus) showed different self-cleavage activities. N-phosphoryl Histine and Ser-His dipeptide could cleave nucleic acids, proteins and esters in neutral medium. Based on a simple model, a pathway of 'co-evolution of protein and nucleic acid' was proposed.

Amino Acids↗

Synthesis, in vitro anticancer evaluation, and interference with cell cycle progression of N-phosphoamino acid esters of zidovudine and stavudine.

A series of N-diisopropylphosphoryl (DIPP) L-amino acid ester prodrugs of zidovudine (AZT) (3a-3e) and stavudine (d4T) (4a-4e) has been prepared. The activity of these compounds against MCF-7 cells (human pleural effusion breast adenocarcinoma cell line) and K562 cells (human chronic myeloid leukemia (CML) cell line) was evaluated. In difference from that of AZT amino acid phosphoramidates, the alophatic amino acid esters of AZT were found to be more cytotoxic than the aromatic analogues toward MCF-7 cell. Two DIPP-L-amino acid esters of d4T 4b (CC50 = 83 microM) and 4c (CC50 = 182 microM) were found to be more cytotoxic than the parent drug toward K562 cells. MCF-7 and K562 cell cycle disturbance was investigated showing detectable blockade in the S phase when exposed to biologically active AZT, 3a, 3b, 3c, 4b and 4c, indicating that they inhibit cell growth by blocking cell cycle progression. Together with previous reports, present findings suggest that anti-breast cancer activity of AZT may be due to hamper DNA synthesis.

Antineoplastic Agents↗

Reconstruction of intraoral defects after cancer surgery using cervical pedicle flaps.

PURPOSE: This article reports the results of using cervical myocutaneous flaps for reconstruction of small- and medium-sized oral defects. PATIENTS AND METHODS: One hundred thirty-one cervical pedicle flaps were used for reconstruction of the defects after resection of oral cancer. Primary sites of the lesions were the tongue, buccal mucosa, floor of the mouth, and lower gingiva. RESULTS: Infrahyoid myocutaneous flaps were used in 53 cases, sternocleidomastoid flaps in 47 cases, and platysma flaps in 31 cases. Among the 131 patients, there was complete necrosis of the skin paddle in 5 cases and partial necrosis in 7 cases. The success rate was 92.5%, 89.4%, and 90.3%, respectively for the 3 types of flaps. CONCLUSIONS: It was concluded that cervical pedicle flaps have clinical value in selected patients needing reconstruction of small- and medium-sized defects after intraoral cancer surgery.

Adult↗

[The effect of Herba Erigerontis Compound on epithelial dysplasia of leukoplakia and lichen planus].

OBJECTIVE: To explore the effective Chinese medicine to prevent and treat oral precancerous lesions,and study the clinical therapeutic effect of Erigerontis Compound and its cellular dynamic mechanism. METHODS: Select 45 volunteers suffering from leukoplakia(LK) and lichen planus(LP)who were divided int treatment and control groups. Treatment group(TG) took Herba Erigrontis Compound capsule for 3 months, Control group(CG) received YUN ZHI Polysacchrodepepitide and vitamin A capsule The results of variation of clinical symptoms, histopathology,and proliferative cell nucleic antigen (PCNA) were observed and compared. RESULTS: In 79.2% case the degree of epithelia dysplasia was decreased and the TG was less than that of CG; the positive cell counts of PCNA of TG fewer than that of CG obviously;the symptom of TG lessen. All of these of TG were better than that of CG. CONCLUSION: Herba Erigerontis Compound Capsule can prevent and treat LK and LP confirmly. Its anticanceration mechanism is to affect actively the cellular dynamics.

English Abstract↗

[Observation of plasma levels of beta-endorphin in patients with trigeminal neuralgia].

OBJECTIVE: To observe the relationship between plasma levels of beta-endorphin and trigeminal neuralgia. METHODS: During the attacks of trigeminal neuralgia, beta-endorphin levels of plasma from external jugular, cubital fossa vein blood ipsilateral to the pain and contralateral external jugular vein blood were assessed by sensitive radioimmunoassay in 12 cases, after operations the venous blood from the ipsilateral external jugular vein was sampled again, the external jugular vein blood of 12 normal volunteers was collected as control. RESULTS: The plasma levels of beta-endorphin in patients with trigeminal neuralgia were significantly lower than that in normal volunteers (P<0.05). CONCLUSION: The lowered plasma beta-endorphin levels may be an important factor for the development of pain in patients with trigeminal neuralgia, which may result in pain and neurogenic inflammation that can not be controlled in central nervous system and peripheral nerve terminals.

English Abstract↗

Electrospray ionization mass spectra of amino acid phosphoramidates of adenosine.

Amino acid phosphoramidates of adenosine were synthesized and determined by positive and negative ion electrospray ionization mass spectrometry (ESI-MS) in conjunction with tandem mass spectrometry (MS/MS). The fragmentation pathways were investigated. In the positive ion mass spectra abundant characteristic fragment ions appeared, and many complementary ions were found. In the negative ion mass spectra only a few fragment ions were observed, and most of them contained phosphoryl groups. The results show that ESI-MS is a useful tool for structural determination of amino acid phosphoramidates of nucleosides.

Adenosine↗

Comparison of inactivation and unfolding of methanol dehydrogenase during denaturation in guanidine hydrochloride and urea.

The activity and the conformational changes of methanol dehydrogenase (MDH), a quinoprotein containing pyrrolo-quinoline quinone as its prosthetic group, have been studied during denaturation in guanidine hydrochloride (GdnHCl) and urea. The unfolding of MDH was followed using the steady-state and time resolved fluorescence methods. Increasing the denaturant concentration in the denatured system significantly enhanced the inactivation and unfolding of MDH. The enzyme was completely inactivated at 1 M GdnHCl or 6 M urea. The fluorescence emission maximum of the native enzyme was at 332 nm. With increasing denaturant concentrations, the fluorescence emission maximum red-shifted in magnitude to a maximum value (355 nm) at 5 M GdnHCl or 8 M urea. Comparison of inactivation and conformational changes during denaturation showed that in general accord with the suggestion made previously by Tsou, the active sites of MDH are situated in a region more flexible than the molecule as a whole.

Alcohol Oxidoreductases↗

[Huge thoracic wall defect repaired by tissue engineered bone transplantation].

OBJECTIVE: A rare huge desmoplastic fibroma on thoracic wall in 1 female case of 25 years old was resected, and the accompanying huge thoracic wall defect, ribs and soft tissues were repaired by tissue engineered bone and pedicled flap. The paper aims to explore the clinical results of early stage after operation. METHODS: Autogeneic bone marrow stromal cells (MSC) were obtained from bone marrow puncture of iliac bone and isolated and cultured according to the Houghton's methods, MSC were directively induced and differentiated to osteoblasts. Allogeneic ribs were made to the bio-derived bone scaffold materials after treatment of decell, deantigen, decalcification and dry freezing. 5 x 10(6)/ml MSC were cocultured with the bio-derived bone for 6 days in vitro. After intact resection of tumor, the diaphragm flap was applied to repair pleural cavity, the three defect ribs were repaired by tissue engineered bone and the soft tissue defect was repaired by transfer of pedicled ipsilateral abdominal flaps. RESULTS: The patient recovered well with first intention. Followed up for 3 months, tissue engineered ribs were matured in vitro and the heart and pulmonary functions were improved markedly. CONCLUSION: The tissue engineered bone constructed by autogeneic MSC is advantageous in individual treatment.

Adult↗

The influence of exogenous nerve growth factor on inferior alveolar nerve regeneration in silicone tubes.

OBJECTIVE: To explore the effects of exogenous nerve growth factor (NGF) in the regeneration of adult white rabbit inferior alveolar nerves within silicone tubes. METHODS: Twenty-four adult white rabbits were selected. Bilateral 8 mm inferior alveolar nerve gaps were created, and the proximal and distal stumps were inserted into a 12 mm silicone tube. The right side silicone tube was filled with exogenous NGF (experimental group) and the contralateral side was filled with saline (control group). Regeneration of the nerves was assessed by histological and nerve eletrophysiological observation. Total number of the regenerated myelinated fibers, conduction velocity of the nerves, thickness of myelin sheaths, and cross-section area of myelinated nerve fibers between the experimental and control groups were compared. RESULTS: The results show that NGF significantly increased the number of myelinated fibers. The experimental group demonstrated more myelinated fibers than the controls at 12 and 18 weeks. At the same time following surgery, the myelin sheath thickness and the cross-section area of myelinated fibers in the experimental group were significantly greater than those in the controls. At 12 and 18 weeks, the conduction velocity of regenerated nerves in the experimental group were greater than those of the control. CONCLUSION: This study suggests that exogenous NGF can enhance regeneration of the inferior alveolar nerves and recovery of their sensory function.

Animals↗

[Clinical application study of intraoral high-level mandibular neurotomy: Reported of 19 cases]

Trigeminal neuralgia is a common disease in clinical practice. The recurrence rate after avulsion is relatively high. In order to reduce the recurrence rate, the author developed a new method and operated on 19 cases with intraoral high level trigeminal neurotomy based on 21 cases of adult human skull anatomy. The method is simple, safe and in good condition. The author emphasized that the proper management of the buccal branch during operation may have a close relation with the post-operative recurrence rate.

Journal Article↗

Phosphoryl transfer reaction regulated by amino acid side chains: a model for phosphoproteins.

Through a kinetic study of the reaction of phosphoamino acids as incubated in alcohol, it was found that the inter- and intramolecular phosphoryl transfer reactions were regiospecific and stereoselective. First, the phosphoryl transfer reaction required the regio-specifically neighboring alpha-carboxy group activation of amino acid but not beta-carboxy group. The intramolecular side chain catalytic effects relative to hydrogen for N-phosphoamino acids compared to N-phosphoglycine were a 119-to 4-times enhancement of the phosphoryl transfer reaction, respectively. Secondly, the intramolecular N-->O phosphoryl transfer migration was highly stereoselective, since the reaction rate constant of phosphoallothreonine relative to its diastereomeric threonine was reduced to half. The pentacoordinate transition states modulated by the amino acid side chains were demonstrated by the formation rates of intramolecular pentacoordinate spiro mixed anhydride compounds.

Amino Acids↗

Detection of the organophosphorus nerve agent sarin by a competitive inhibition enzyme immunoassay.

Two artificial antigens, NalphaNepsilon-di(O,O-diisopropyl) phosphoryl L-lysine (DIP)- bovine serum albumin (BSA) conjugate (DIP-BSA) and DIP-KLH (keyhole limpet hemocyanin), were synthesized. Antibodies against sarin (O-isopropyl methylphosphonofluoridate) were obtained after immunization of rabbits with DIP-KLH conjugate. A competitive inhibition enzyme immunoassay (CIEIA) was developed to detect the organophosphorus nerve agent sarin. The antibody solutions could be inhibited by sarin as low as 10(-6) mol/l, and the standard curve was linear over 3 orders of magnitude. The coefficients of intraassay and interassay variation of this method were 5.4-6.2% (n = 11) and 8.0-9.5% (n = 6) at a sarin concentration range of 10(-3)-10(-6) mol/l, respectively. The recovery of sarin in water samples at the concentration of 5 x 10(-5) mol/l was in the range of 96.8-102.5%. The specificity of the antiserum was assessed by comparing the inhibition induced by sarin with soman, Vx, isopropyl alcohol and isopropyl methyl phosphonic acid. The results showed that less than 5 mmol/l soman, 2 mmol/l Vx, 16 mmol/l isopropyl alcohol and 8 mmol/l isopropyl methyl phosphonic acid did not influence the determination of sarin in water samples.

Animals↗

[The diagnosis and the treatment on lingual thyroid]

Lingual thyroid is a rare example of ectopic thyroid.This paper reported three cases of lingual thyroid(all female,aged between 16 and 61 years) were discussed with diagnosis and treatment.A transoral excision using the median total glossotomy and precervical excision was performed through a transsuprahyoid approach.Postoperative complications is not developed.The approach above mention is better than that of median labiomandibular glossotomy.

Journal Article↗

[The fabrication technique of Plat casting ceramic prosthesis: A preliminary study]

Microspectrophotometer and transmitted electron microscope (TEM) were used to study the change of DNA synthesis and ultrastructure after fibronection(FN) acted on cultured periodontal ligament cells (PDLC).The results showed that the data of nuclus area,nuclus total absorbs and nuclus mean absorbs of PDLC in FN group was higher than control(P<0.01).Under the TEM we observed that in FN group there were more euchromatin in cell nuclues and more organ cells such as microfilaments,chondriosomes and endoplasmic reticulum in cytoplasm.It suggested that FN can accelerate periodontal regeneration by promoting DNA and protein synthesis of PDLC.

Journal Article↗