Biomedical subjects

Z P Yang

Publications and source records attributed to Z P Yang.

At least 19 recordsLinked to original sources

PubMed2001

[The application of transposition of the gastrocnemius muscle in the limb-salvage operations of the proximal tibial tumors].

OBJECTIVE: To evaluate the efficacy of transposition of the gastracnemius muscle in the limb-salvage operation of the proximal tibial tumor. METHODS: From 1995, transposition of the gastrocnemius muscle was applied to cover the devitalized bone, bone cement or autologous bone graft in 15 cases with tumors of the proximal tibia (transposition of medial heads of gastrocnemius muscle in 12 cases, and lateral heads of gastrocnemius muscle in 3 cases respectively). Among them, there were 7 osteosarcomas, 5 giant cell tumors, 1 malignant fibrous histocytoma, 1 chondrosarcoma and 1 osteoblastoma. The operations included segmental devitalization with 95% alcohol in 7 cases, knee reconstruction of the unilateral tibial plateau with iliac graft in 5 cases, segmental devitalization with microwave in 2 cases, local resection and bone graft in 1 cases. RESULTS: Apart from 2 cases whose wounds needed suturing again due to the liquefaction of the subcutaneous fat around the incision, no wound complications were occured in other 13 patients. No significant loss in the function of the leg and ankle was observed after transposition of the gastrocnemius muscle. There was no local recurrence, but 3 patients died due to lung metastases. CONCLUSION: Transposition of the gastrocnemius muscle after resection of promixal tibial tumors can improve the local blood supply, cover the deep structures and prevent from the failure of limb-salvage operation due to wound complications.

Adolescent↗

PubMed2000

Apoptosis of osteoclast-like cells induced by alendronate is related to Fas gene expression.

OBJECTIVE: To detect the mechanism of alendronate during inhibition of bone resorption by inducing apoptosis of osteoclasts and its relationship with the Fas gene. METHODS: The osteoclast-like cells (OCLs) from a giant cell tumor in vitro were used. After treatment with alendronate for 48 hours, the OCLs were identified by fluorescence microscope, transmission electron microscope, in situ end labeling (TUNEL), HE staining, in situ hybridization with Dig-Fas Probe, and immunohistochemistry with anti-Fas antibodies. RESULTS: The detachment rate of OCLs was 76% after exposure to alendronate, while the control cell detachment rate was only 3%. The nonadherent OCLs showed the features of cell contraction, pyknosis, chromatin condensation connecting with nuclear membrane to form circle or crescent bodies, and occasional nuclear fragmentation. The detached OCLs were positive by in situ end labeling, and the control group was negative. Nonadherent OCLs were ultrastructurally consistent with apoptosis (shrunken cells with pyknotic nuclei, chromatin condensation connecting with nuclear membrane, mitochondria recruitment with intact structure, and loosening of endoplasmic reticulum). The results by in situ hybridization and immunohistochemistry indicated that the Fas gene expression of nonadherent OCLs were positive, but the controls were negative. CONCLUSION: Alendronate promotes apoptosis of the OCLs and it is related with the expression of the Fas gene.

Alendronate↗

PubMed1999

Different role of carboxylesterases in toxicity and tolerance to paraoxon and DFP.

The contribution of carboxylesterase (CarbE) to toxicity and tolerance to the organophosphorus anticholinesterases (OP-antiChE) paraoxon (diethyl p-nitrophenyl phosphate) and DFP (diisopropylphosphorofluoridate) was investigated in rats. Daily injections (20 days) of paraoxon (0.33 micromol/kg) or DFP (2.72 micromol/kg) reduced AChE activity in brain to 29 or 16% and in diaphragm to 58 or 54%, respectively. The animals tolerated an accumulated 6-fold LD50 dose and survived an LD90 dose of carbachol, indicating tolerance to this cholinergic agonist. A single dose of paraoxon or DFP significantly reduced CarbE activity of plasma, lung and liver. After paraoxon, rapid recovery was seen of plasma and liver CarbE while recovery after DFP was much slower. Daily pretreatment with the CarbE inhibitors CBDP (2-[o-cresyl]-4H-1,2,3-benzodioxa- phosphorin-2-oxide) (7.22 micromol/kg, s.c.) or iso-OMPA (tetraisopropylpyrophosphoramide) (8.76 micromol/kg, i.p.), followed by paraoxon (0.33 micromol/kg, s.c.) 30 min later, prevented the development of tolerance to paraoxon and potentiated its toxicity. Rats died on day four of the combined treatment. The CarbE inhibitors neither potentiated the DFP toxicity, nor prevented tolerance development to DFP. We conclude that rat plasma CarbE provides a significant protection against paraoxon toxicity because its rapid reactivation can reduce the toxicity of repeated paraoxon applications and thus contribute to tolerance development. This same mechanism does not apply to DFP toxicity, as inhibition of CarbE of plasma, liver and lung neither potentiated its toxicity, nor prevented tolerance development. These findings confirm previous observations that CarbE detoxification is of greater importance for highly toxic OP-antiChEs such as nerve agents and paraoxon than for less toxic ones such as DFP.

Acetylcholinesterase↗

PubMed1998

Prevention of tolerance to the organophosphorus anticholinesterase paraoxon with carboxylesterase inhibitors.

The contribution of carboxylesterase (CarbE) to the development of tolerance to the organophosphorus anticholinesterase (OP-ANTIChE) paraoxon (diethyl p-nitrophenyl phosphate) was investigated in rats. Daily injections (20 days) of paraoxon (0.09 mg/kg) led to a cumulative dose that was 9.0-fold higher than the acute ED50 of 0.20 mg/kg, s.c. During this period, the rats did not demonstrate visible signs of cholinergic hyperactivity nor did they die, despite the persistence of critically reduced brain acetylcholinesterase (AChE) activity (20-30% of control). In addition, none of these rats died following the administration of a dose of carbachol (3.1 mg/kg, i.p.) that was an LD90 in untreated rats. Daily treatment with the CarbE inhibitors CBDP [2-(o-cresyl)-4H-1,3,2-benzodioxaphosphorin-2-oxide] (2 mg/kg, s.c.) or iso-OMPA (tetraisopropylpyrophosphoramide) (3 mg/kg, i.p.) followed by paraoxon (0.09 mg/kg, s.c.) 60 min later prevented the development of tolerance to paraoxon, since signs of cholinergic hyperactivity were observed and rats died on day 4 of the combined treatment. In tolerant rats, one-time CBDP or iso-OMPA pretreatment increased toxicity to paraoxon, causing the death of all rats within 60 min. The increase in paraoxon toxicity was correlated with inhibition of a plasma CarbE, with high affinity toward alpha-naphthyl acetate (alpha-NA) and to the inhibitors CBDP, iso-OMPA, and paraoxon. Inhibition of a plasma CarbE with high affinity toward p-nitrophenyl acetate (p-NPA) and low affinity to the above inhibitors did not potentiate paraoxon toxicity significantly. Neither the liver CarbEs, which showed high affinity to iso-OMPA, nor the inhibition of butyrylcholinesterase (BuChE) by iso-OMPA in plasma and liver potentiated paraoxon toxicity. By eliminating plasma CarbE (alpha-NA) as potential binding sites for paraoxon with either CBDP or iso-OMPA, paraoxon can exert its toxicity to a greater extent at its specific target site, the functionally important AChE at cholinergic synapses. It is concluded that plasma CarbE (alpha-NA) provided a significant protection against paraoxon intoxication and that the inhibition of this enzyme prevented the tolerance development seen with repeated paraoxon treatments.

Acetylcholinesterase↗

PubMed1996

Diisopropylphosphorofluoridate-induced muscle hyperactivity associated with enhanced lipid peroxidation in vivo.

Acute exposure to acetylcholinesterase (AChE) inhibitors such as organophosphates and carbamates induces functional changes at the neuromuscular junctions, leading to fasciculations that ultimately cause muscle fiber necrosis. There is recent evidence that oxygen free radical formation may be a factor in the toxicity of these insecticides. One of the targets of free radical-induced injury is lipid peroxidation. The role of lipid peroxidation in diisopropylphosphorofluoridate (DFP)-induced muscle necrosis was investigated by quantifying two products resulting from the oxidation of lipids in muscle tissue-the thiobarbituric acid-malondialdehyde complex (TBA-MDA) and F2-isoprostanes, the latter being a novel and extremely accurate marker of lipid peroxidation in vivo. When compared with control animals, significant increases in MDA of 96% and in F2-isoprostanes of 56% were found in the diaphragms of rats treated with 2.0 mg/kg DFP after 60 min (P < 0.01). In rats pretreated with the neuromuscular blocking agent d-tubocurarine or the lazaroid U-78517F, an antioxidant, no DFP-induced increases in either MDA or F2-isoprostanes were observed. It is suggested that the AChE inhibitor-induced cholinergic hyperactivity initiates that accumulation of free radicals leading to lipid peroxidation, which may be the initiator of the AChE inhibitor-induced cell injury.

Animals↗

PubMed1996

Diisopropylphosphorofluoridate-induced cholinergic hyperactivity and lipid peroxidation.

In the present study, the association between acetylcholine (ACh)-induced muscle necrosis and the appearance of lipid peroxidation products was investigated. Lipid peroxidation in this injury was quantified by the malondialdehyde-thiobarbituric acid complex (TBA-MDA) using HPLC. To induce muscle necrosis, rats were treated with 1.0 or 2.0 mg/kg diisopropylphosphorofluoridate (DFP), an irreversible inhibitor of AChE that induced muscle fasciculations, and were euthanized 30-120 min after the DFP treatment. DFP caused a dose-dependent increase in AChE inhibition, muscle fasciculations, TBA-MDA formation, and muscle necrosis. Reduction of glutathione (GSH) by pretreatment with buthionine sulfoximine (BSO) potentiated the DFP-induced changes in TBA-MDA and caused an increase in the number of necrotic muscle fibers. Prevention of fasciculations by pretreatment with cholinergic antagonists such as atropine and d-tubocurarine, before DFP, inhibited the increase in lipid peroxidation, and significantly attenuated the muscle fiber necrosis. Without affecting muscle fasciculations, the antioxidant U-78517F prevented the increase in lipid peroxidation and reduced the number of muscle fibers that became necrotic. It is suggested that DFP-induced AChE inhibition causes pronounced muscle hyperactivity as the initial step that triggers free radical-induced lipid peroxidation as the final common pathway to muscle injury.

3,4-Methylenedioxyamphetamine↗

PubMed1996

Treatment of labial fenestration of maxillary central incisor.

A case of external inflammatory root resorption and labial fenestration in a maxillary central incisor is presented. The root canal was dressed with pure calcium hydroxide mixed with normal saline for 1 month before it was obturated with gutta percha and apicoectomy surgery undertaken to attempt primary closure of the fenestration. The PDL and the fenestration healed uneventfully.

Alveolar Bone Loss↗

PubMed1995

Systemic dissemination of Chlamydia pneumoniae following intranasal inoculation in mice.

Although Chlamydia pneumoniae is a respiratory pathogen, there is increasing evidence of involvement of the organisms in anatomic sites other than the respiratory tract. A mouse model was used to study dissemination of organisms following intranasal, intravenous, and subcutaneous inoculation with C. pneumoniae. After inoculation by any of the three routes, the organism was isolated consistently from lungs and spleen. It was also detected in peritoneal macrophages after intranasal and intravenous inoculation. The ease with which the organism was disseminated in the mouse model raises the question of whether similar spread from the respiratory tract occurs in human C. pneumoniae infection.

Animals↗

PubMed1994

Current status of lung cancer diagnosis and treatment in Shanghai.

The status of diagnosis and treatment of lung cancers discovered during 1 year in the Shanghai population are presented. A total of 940 lung cancers was detected from inhabitants of 35-64 years of age, with a male/female ratio of 1.8:1. Pathology showed 35.7% adenocarcinoma and 35.1% squamous cell carcinoma. There was a predominance of adenocarcinoma (47.6%) in females and of squamous cell carcinoma (44.6%) in males. Most (68.6%) of the lesions detected were already advanced in contrast to 14.7% of Stage I disease. The need for vigilance on the part of doctors was demonstrated by the fact that 23.3% of patients were seen by the doctor within 1 month after presenting with symptoms and 44.5% of them had their diagnosis suspected within 1 month after their first hospital visit. The treatment consisted of surgery for 33.3%, chemotherapy for 35%, traditional Chinese medicine for 20% and symptomatic management for 9.6% of patients. As only 55.8% Stage I patients were treated by surgery, the treatment protocol seemed to be improperly biased. The adequate training of health workers was shown by the fact that 79.7% of these patients were confirmed by pathology and/or cytology and most of the Stage I lesions were diagnosed outside the hospital.

Adult↗

PubMed1994

Ultrastructural lung pathology of experimental Chlamydia pneumoniae pneumonitis in mice.

The ultrastructural lung pathology of Swiss Webster mice on days 2, 4, 7, 11, 15, and 21 after intranasal inoculation of Chlamydia pneumoniae AR-39 is described. The inflammatory infiltrate was predominantly polymorphonuclear leukocytes on day 2. By day 7, mononuclear cells were most prominent in the infiltrate. On day 2, chlamydial inclusions were found frequently in the bronchial ciliated epithelial cells and less frequently in the interstitial cells that appeared to be macrophages. Free particles of all developmental forms of the chlamydial microorganism were found in the bronchial lumen and alveolar space. These particles were likely organisms released from infected cells. Inclusions as well as free particles were difficult to find after day 4. These ultrastructural observations suggest an immunopathologic basis for the acute phase of the disease process.

Acute Disease↗

PubMed1994

Multiple canals in a mandibular first premolar. Case report.

It has been recorded that the occurrence rate of more than one canal in the mandibular first premolar varies between different races. This report presents the diagnosis and treatment of a mandibular first premolar with multiple root canals in a young male Asian. It is noted that knowledge of canal morphology, careful interpretation of the radiograph, and tactile sense during treatment constitute the major factors in achieving success with endodontic therapy in cases of complex root canal morphology.

Adult↗

PubMed1993

A mouse model of Chlamydia pneumoniae strain TWAR pneumonitis.

Chlamydia pneumoniae is a common cause of acute respiratory infections in humans. We evaluated mice as experimental animals for C. pneumoniae. Intranasal inoculation of Swiss Webster mice with C. pneumoniae induced a prolonged course of lung infection, as demonstrated by reisolation of organisms from lungs (at 42 days) and persistence of lung pathology (> 60 days). The lung pathology was characterized by patchy interstitial pneumonitis with predominantly polymorphonuclear leukocyte infiltration in the early and mononuclear cell infiltration in the later stages of infection. Inoculated mice developed serum immunoglobulin G antibody responses and partial resistance against rechallenge inoculation. The other mouse strains tested, Icr, BALB/cAnN, C57BL/6N, C3H/HeN, and B6C3F1, were shown to be susceptible to C. pneumoniae. The mouse model should be useful for investigating the immunopathogenesis of C. pneumoniae infections.

Animals↗

PubMed1993

[The degradation mechanism of penequine hydrochloride in aqueous solutions].

Penequine hydrochloride (I) is a new potent anticholinergic drug, the degradation mechanism of I in aqueous solutions is reported in this paper. I is an ethereal compound, stable in neutral and alkaline solutions, but it decomposes in strong acidic solutions. Its main degradation products have been separated and identified by means of TLC, MS, GC/MS and GC/FTIR. With reference to the general degradation rule of ethereal compound and the structure of the degradation products, we deduced that the ether linkage of I splits in acidic solutions by the catalysis of hydrogen ion, producing 3-quinuclidinol (DP1) and 1-phenyl-1-cyclopentyl glycol. The latter turns into 1-phenyl-1-cyclopentyl acetaldehyde through dehydration and rearrangement. In addition, small amounts of other degradation compounds, e. g. benzaldehyde, acetophenone, phenylcyciopentyl ketone, etc. have also been found, but the mechanism remains to be further studied.

Cyclopentanes↗

PubMed1993

[Prognostic factors in lung cancer based on Shanghai population].

Life table, Cox model and Cox multivariate model were used to measure the prognostic factors in 1417 new prevalent lung cancer cases in Shanghai population of urban area. There were 3 main prognostic factors in lung cancer as follows: a. histologic type was correlated to prognosis, among which, squamous type was the best, SCLC the worst, the factor influenced to prognosis of various types was stage and therapy. b. the earlier stage the better prognosis, and related to a optimal therapy. c. Combined therapy was good for prognosis, it was optimal for either surgical or nonsurgical therapy. Early detection, extension of combined therapy and make public of knowledge on lung cancer were encouraged.

Adenocarcinoma↗

PubMed1992

Healing of a sinus tract of periodontal origin.

A sinus tract adjacent to teeth is usually considered to be of endodontic origin and root canal therapy is the primary treatment to achieve healing. A case of a sinus tract is presented in which a suspected endodontic-periodontic lesion was successfully treated by periodontal therapy alone. The sinus tract healed and the radiograph showed bony repair.

Adult↗

PubMed1991

Adsorptive preconcentration for voltammetric measurements of trace levels of chlorprothixene.

The psychotherapeutic drug chlorprothixene is shown to adsorb strongly onto a glassy carbon surface in an open circuit. By using this phenomenon to preconcentrate the drug at a glassy carbon electrode prior to differential-pulse voltammetric measurements, sensitivity at the ppb level is readily achieved. The adsorptive stripping response was evaluated with respect to electrolyte, solution pH, accumulation time, concentration dependence and other variables. A linear peak current-concentration relationship was observed up to 1 microgram ml-1 of chlorprothixene; the relative standard deviation (at the 0.6 microgram ml-1 level) is 3.2%. For a preconcentration time of 10 min, the detection limit was found to be 2 ng ml-1. The open circuit preconcentration/medium exchange/voltammetric scheme was used to eliminate interference from sample solutions. The application of the method to human urine samples is described.

Adsorption↗

PubMed1990

A 3-year follow-up of a homotransplanted tooth from a tooth bank.

A successful case of homologous tooth transplantation is presented. A maxillary second premolar obtained from a tooth bank was implanted into a fresh central incisor extraction site. A 3-yr follow-up radiograph indicated satisfactory apical healing and minimal replacement resorption. Clinically, the transplantation site was free of symptoms and there was no evidence of periodontal disease or tooth mobility.

Adult↗

PubMed1990

Continuing root formation following apexification treatment.

A case report is presented in which continuing root formation occurred in an immature mandibular second premolar after calcium hydroxide apexification treatment. An apical hard tissue barrier was accompanied by a separate disto-apically growing root 18 months posttreatment. Histologic evaluation of the root revealed immature hard tissue mixed with calcium hydroxide, connective tissue and bone, apically in the original root canal. In the separate new formed part of the root, pulp tissue, odontoblasts, predentin, cementum and an apical foreman could be identified.

Calcium Hydroxide↗