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Biomedical subjects

L Zeng

Publications and source records attributed to L Zeng.

At least 217 records · Page 12Linked to original sources
PubMed1994

Kneglomeratanol, kneglomeratanones A and B, and related bioactive compounds from Knema glomerata.

One new phenylalkyl phenol, kneglomeratanol [1], and two new acetophenones, kneglomeratanones A [2] and B [3], together with ten known compounds, 3-(12'-phenyldodecyl)-phenol [4], 3-(10'-phenyldecyl)-phenol [5], 5-pentadecylresorcinol [6], 5-(10'-phenyldecyl)-resorcinol [7], 5-(12'-phenyldodecyl)-resorcinol [8], 2,4-dihydroxy-6-(10'-phenyldecyl)-acetophenone [9], 2-hydroxy-6-(12'-phenyldodecyl)-benzoic acid [10], formononetin, biochanin A, and 8-O-methylretusin, have been isolated from the stem bark of Knema glomerata. Brine shrimp lethality was used for the activity-directed chromatographic fractionations. All of these compounds showed moderate but significant toxicities to three human tumor cell lines and inhibited the growth of crown gall tumors on discs of potato tubers.

Acetophenones↗
PubMed1994

A noninvasive functional evaluation following peripheral nerve repair with electromyography in a rat model.

A new bipolar surface electrode array was designed and constructed for a noninvasive "closed" functional evaluation with electromyography following sciatic nerve transection in a rat model. This "closed" method was compared with a conventional one-shot "open" measurement. Nerve conduction velocity and distal latency were calculated. Data obtained from the recordings from different animals as well as from the same animal at different points in time yielded excellent reproducibilities. There is no difference in the mean values whether nerve conduction velocity and distal latency are obtained by "closed" or "open" measurements. Correlation was significant (p < 0.01; rNCV = 0.77, rDL = 0.63) between these two methods. The results lead to the conclusion that the noninvasive functional evaluation with the parameters of nerve conduction velocity and distal latency introduced in the present study could be employed as a reliable method for serial functional evaluations following nerve transection in a long-term study in a rat model.

Animals↗
PubMed1994

[Studies on MDA and MDA/MDAa in patients with retinitis pigmentosa].

With fluorimetry, the concentration of malondialdehyde (MDA) and the ratio of MDA before and after the blood platelets activated (MDA/MDAa) were determined in patients with retinitis pigmentosa (RP). The results showed the above two parameters were statistically higher than those of the normal controls, which indicated the superoxidation metabolism increased and the blood was in a state of hypercoagulation in RP patients. The reasons for the results and their roles in RP disease were discussed. Treatments with anti-lipid, and anti-coagulation drugs combined with Chinese medicines were suggested.

Adolescent↗
PubMed1993

In vitro effects of recombinant human interferon gamma on human mesothelioma cell lines.

Malignant mesothelioma is a tumor arising from serous surfaces and often related to asbestos exposure. Malignant mesothelioma is resistant to various forms of therapy. Radiotherapy, surgery or chemotherapy only slightly improve prognosis. IFN-gamma produces complete or partial responses in stage-I patients with malignant mesothelioma. The in vitro biological effect of IFN-gamma on malignant mesothelioma cells remains poorly elucidated. In the present study, 32 well-characterized human mesothelioma cell lines (HMCL) were treated with r-hu IFN-gamma at 4 doses and cell growth was determined by a colorimetric method (MTT assay). Among the 32 HMCLs tested, II exhibited significant cell-growth inhibition; 16 were insensitive to r-hu IFN-gamma, and 5 were slightly inhibited. The sensitive cell lines were strongly inhibited by r-hu IFN-gamma. Our results show that HMCL exhibit a large range of responses to r-hu IFN-gamma, some of which can be compared with those obtained in vivo in humans.

Aged↗
PubMed1993

[Squamous cell carcinoma associated antigen levels in monitoring the response to surgical treatment for patients with esophageal carcinoma].

The serum levels of the squamous cell carcinoma associated antigen (SCCAg) were measured in 50 patients with esophageal carcinoma by immunoradiometric assay before and after surgery. 32 patients were subjected to curative surgery, 15 palliative operation, 3 exploratory thoracotomy. After curative surgery, the elevated level dropped rapidly to normal within 72 hours. The SCCAg levels showed statistical differences. In patients having palliative operation, the SCCAg levels declined but usually remained above the normal range. After exploratory thoracotomy, the SCCAg levels usually increased. Because SCCAg responded well to the effects of surgery, it was considered to be a very useful tumor marker in monitoring the response to surgical treatment for patients with esophageal carcinoma.

Adult↗
PubMed1993

[Clinical significance of serum SCC Ag in patients with squamous cell carcinoma of the lung].

To evaluate its clinical significance as a tumor marker, the serum level of squamous cell carcinoma associated antigen (SCC Ag) was studied by immunoradiometric assay in 59 patients with histologically proved lung cancer (32 squamous cell carcinomas, 23 adenocarcinomas and 4 small cell carcinomas). Carcinoembryonic antigen (CEA) was measured by radioimmunoassay simultaneously. The serum levels of SCC Ag and CEA were found above the normal range in 71.9% and 28.1% of squamous cell carcinomas, 26.1% and 34.8% of adenocarcinomas and 0% and 25% of small cell carcinomas respectively. In squamous cell carcinomas, the positive rate of SCC Ag increased with progression of clinical stage. With regard to the preoperative serum level dropped dramatically after surgery (P < 0.05). The change would be more outstanding after radical surgery (P < 0.001). The serum level of SCC Ag can be used to effectively monitor the course of disease, and could be used as an important item during the postoperative follow-up.

Adenocarcinoma↗
PubMed1993

Early osteoinduction in rats is not altered by fibrin sealant.

The angiogenic and fibrogenic activities of fibrin sealant (Tisseel) suggest that it could enhance osteoinductivity during the first days after implantation. To test this hypothesis, the osteoinductivity of sealed and unsealed bone matrix gelatin was tested by implantation into rat abdominal wall muscle pouches for two to ten days. A sponge of collagen with or without fibrin sealant was used for control. Alkaline phosphatase (ALPase) was employed to quantify osteoinduction, and myeloperoxidase (MPO) was used to determine the inflammatory reaction. Plain histologic analysis of bone matrix gelatin implants at Days 2, 4, and 10 did not demonstrate any significant differences between sealed and nonsealed implants. Histologic analysis at Day 21 confirmed the osteoinductivity of the implant. The combination of bone matrix gelatin and fibrin sealant induced an early significant increase in ALPase activity, which could be interpreted as early induction of histologically undetectable osteogenesis. A simultaneous increase in the level of MPO suggested that the bone matrix gelatin/fibrin sealant-induced ALPase reaction might be caused by an inflammatory process, but neutrophil counting did not correlate to the MPO data. Morphometry, however, seems to be insufficient to assay a heterogenous histologic distribution of singular cells. It is proposed that the ALP/MPO ratio may be used as an inflammation-independent marker of osteogenesis. This study does not support the notion of an osteoinductive potency of fibrin sealant per se; however, it is clear that fibrin sealant does not impair bone matrix gelatin-dependent osteoinduction.

Abdominal Muscles↗
PubMed1992

The study of G6PD in erythrocyte and lens in senile and presenile cataract.

The G6PD activity of erythrocytes in 113 male patients with senile and presenile cataract and 86 controls, and G6PD activity of lens in 30 patients with senile cataract and 42 controls were reported. The cataractous group had higher frequency of G6PD deficiency and lower average G6PD level in erythrocytes and lenses, but without statistical significance. The frequency of G6PD deficiency of erythrocytes in presenile cataractous group was higher than that of senile cataractous group but with no statistical significance too. However, the average G6PD level of erythrocytes in presenile cataractous group was lower than that of senile cataractous group and with statistical significance (P < 0.05). The G6PD activity of lenses only presenile in the cortex and have a positive correlation with that of erythrocytes. There was a case with deficiency of G6PD both of erythrocytes and cataractous lenses in both eyes. The results indicate that the deficiency of G6PD might be one of the cataractous pathogenetic factor for presenile cataract. Measurement of G6PD activity of erythrocytes among population might be of significance in finding the risk factor for cataract.

Adult↗
PubMed1992

Modern surgical treatment of congenital subluxated lenses.

Traditional surgical management of subluxated lenses is usually associated with a high incidence of operative and postoperative complication and a poor visual outcome. We treated a series of 14 patients (26 eyes) whose visual acuity could not be improved with optical correction (phakic or aphakic) with modern microsurgery and automated suction-cutting devices. Preoperative visual acuity ranged from 0.05 to 0.3. Improvement in post-operative visual acuity was documented in all operated eyes, ranging from 0.4 to 1.0 during a follow-up period ranging from 6 to 59 months (medium 43 months). The only complication was a small accidental cut in the pupillary border in three eyes. Other complication did not occur.

Adolescent↗
PubMed1992

[Hurler syndrome (a case report)].

A case of Hurler syndrome diagnosed by clinical and laboratory examination is reported. The patient's roentgenograms showed the dystrophies of bones, lace-shaped ribs, boat-shaped cranium, fishhook-shaped forefront protrusion of silla trucica. Corneal opacities and high ocular pressure were found in both eyes. VEP measurement suggested the defects of optic nerve. The authors emphasized that visual electric physiological examinations should be used to estimate the visual functions when the patient's refractive medium is opqaue. The differential diagnosis was also briefly discussed.

Child↗
PubMed1992

[Expression and distribution of catechol 2,3-dioxygenase in Escherichia coli].

A series of new plasmids containing xylE gene was constructed based on the shuttle plasmid pTG 402 between E. coli and B. subtilis. The expressed xylE gene product catechol 2,3-dioxygenase (CatO2ase) was measured for its output and distribution, and analysed for its structural hydrophobicity and hydrophilicity. It was demonstrated that the output of CatO2ase was relative to plasmids, host cells, culture time and with or without induction. The enzyme didn't have features of excretional proteins and was mostly distributed inside the cells though a little could be detected in culture medium. It can be used as a selective marker, indicator and monitor in the study of genetic engineering. This research also provides a scientific basis for eliminating pollution of aromatic hydrocabonic compounds with genetic engineering bacteria.

Base Sequence↗
PubMed1991

Identification of a neutralization epitope on the envelope gp46 antigen of human T cell leukemia virus type I and induction of neutralizing antibody by peptide immunization.

We have generated a number of mAb against various epitopes on the external envelope glycoprotein, gp46, of human T cell leukemia virus type I (HTLV-I) from a WKA rat immunized with a recombinant vaccinia virus containing the HTLV-I env gene. Among these mAb, one group of mAb, represented by a mAb designated LAT-27, could neutralize the infectivity of HTLV-I, as determined by a HTLV-I-mediated cell fusion inhibition assay. LAT-27 also interfered with transformation of normal T lymphocytes by HTLV-I in vitro. An antibody-binding assay using overlapping synthetic oligopeptides showed that LAT-27 bound specifically to 10-mer peptides that contained the gp46 amino acid sequence 191-196 (Leu-Pro-His-Ser-Asn-Leu). Antibodies from HTLV-I+ humans interfered with the binding of LAT-27 to gp46 Ag. Sera from rabbits immunized with a LAT-27-reactive peptide, 190-199, conjugated with OVA, but not sera from OVA-immunized rabbits, reacted with gp46 Ag and neutralized infectivity of HTLV-I. These results show that the HTLV-I neutralization epitope recognized by LAT-27 locates to the gp46 amino acids 191-196, and that immunization with a peptide containing the LAT-27 epitope can elicit an HTLV-I neutralizing antibody response.

Animals↗
PubMed1991

Decalcified and undecalcified cancellous bone block implants do not heal diaphyseal defects in dogs.

UNLABELLED: In a previous study it has been shown that granulae of decalcified bone matrix do not induce bony healing of 8-week-old mid-diaphyseal defects in dogs. The aim of this study was to test whether osteoinduction combined with the osteoconductive mechanisms provided by the natural structure of cancellous bone blocks would yield better results. A 30-mm-long diaphyseal defect of the left ulna was created in eight adult mongrel dogs and the bone was stabilized with a plate. A Silastic spacer was inserted in the defect for 8 weeks, followed by implantation of frozen undecalcified or decalcified allogeneic cancellous bone blocks for 16 weeks. Healing was analyzed using morphologic methods. At 16 weeks after implantation all grafts had been resorbed. In the decalcified group one defect healed, while none in the other group did so. The implant material was bioassayed in nude rats for osteoinductivity, which was found to be low in decalcified matrix and not detectable in undecalcified bone. CONCLUSION: Allogeneic cancellous bone blocks, demineralized or not, have no osteoinductive capacity and no osteoconductive function that promotes healing of mid-diaphyseal bone defects in dogs.

Animals↗
PubMed1991

Glyyunnansapogenins G and H: Two New Pentacyclic Triterpenoids of the 18alphaH-Oleana-9(11),12-diene Type from Glycyrrhiza yunnanensis Roots.

Two new pentacyclic triterpenoid sapogenins of the 18alpha H-oleana-9(11),12-diene type named glyyunnansapogenins G and H were isolated from the roots of GLYCYRRHIZA YUNNANENSIS Cheng f. et L. K. Tai. Their structures were elucidated as 18alpha H-oleana-9(11),12-diene-3beta,21alpha,29-triol and 18alpha H-3beta,21alpha-dihydroxyoleana-9(11),12-dien-29-oic acid, respectively, by spectroscopic methods. This is the first report of the occurrence of the 18alpha H series of oleana-9(11),12-diene compounds in nature.

Journal Article↗
PubMed1991

[Small-airway lesions induced by inhalation of asbestos dust in dogs--pathological and aetiological studies].

This paper presents the pathological changes of the small airways of dogs inhaling asbestos dust in the workshop of Xin Kong Asbestos Mine for 1 to 3 years. Dogs of the experimental group showed that variable degrees of dust deposition and fibrous tissue reaction were found in all the three types of the small airways-respiratory bronchioles, alveolar ducts and membranous bronchioles of both lungs. The lesions in the lung increased with the duration of exposure. These changes in the canine small airways resulting from asbestos dust were very much similar to those of the humans. In addition, deposited dust collected from the workshop of the asbestos mine, and 50 dust particles selected randomly in foci were identified in situ by energy dispersive X-ray analysis. Findings demonstrated that the majority of the dust particles in the foci was principally mixed silicate dust. Among them asbestos dust predominated absolutely, and there were more amphiboles than chrysotiles. Therefore, it is concluded that the small airway lesions induced in the dogs are mainly due to mixed asbestos dust, and that there appears to exist a dose-response relationship.

Animals↗
PubMed1991

[Pathological observation of experimental asbestosis treated by hydroxy piperquin phosphate in dogs].

The paper presents experimental asbestosis treated with hydroxy piperquin phosphate (HPQP) in dogs. Results showed that the total cell number of bronchoalveolar lavage fluid, the viability of alveolar macrophages and the enzyme activities of lactate dehydrogenase, acid phosphatase and beta-glucuronidase of alveolar macrophages in treated dogs were higher than those in exposed dogs, asbestos fibers contents in the lungs and the mean scores of lung lesions in the treated dogs were markedly less than those in the exposed dogs. These findings support that HPQP may play a role in protecting alveolar macrophages from damage and inhibiting the progression of lung fibrosis, and that the clinical application of HPQP is somehow evidenced by this study.

Animals↗
PubMed1991

[Quality evaluation of Chinese licorice].

The contents of 12 compounds, viz. glycyrrhizinic acid, uralsaponin A, uralsaponin B, liquiritin, isoliquiritin, liquiritigenin, isoliquiritigenin, glycycoumarin, isoglycycoumarin, licochalcone A, glycyrol and isoglycyrol, present in Chinese licorice, the roots and rhizomes of 8 Glycyrrhiza species collected from 15 districts in China, were determined by high performance liquid chromatographic method. The quality evaluation of Chinese licorice was discussed according to the results of the determinations.

Chromatography, High Pressure Liquid↗