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Biomedical subjects

X H He

Publications and source records attributed to X H He.

16 recordsLinked to original sources
PubMed2001

Killing effects of ganciclovir on human pulmonary adenocarcinoma cell A549 transduced with HSV1-TK gene in vitro and in vivo.

AIM: To observe the killing effects of ganciclovir (GCV) on the human pulmonary adenocarcinoma cell A549 transduced with Herpes simplex virus I type thymine kinase (HSV1-TK) gene in vitro and in vivo. METHODS: A retroviral vector containing the TK gene was constructed and transduced into a pulmonary carcinoma cell A549 by electroporation, to observe the sensitivity of the transfected cell to GCV in vitro and the bystander effect (MTT assay). Tumor cell apoptosis caused by the TK/GCV system was observed with a flow cell meter (FCM) and a scan electronic microscope (SEM). Recombination and expression of the TK gene were examined with DNA PCR and in situ hybridization, respectively. The therapeutic effect of GCV on subcutaneous tumor growth between transfected and parental cells was also compared. RESULTS: The sensitivity of the transfected cell to GCV was 46 times higher than that of the parental cell, and the bystander effect was stronger in high cell density than in low cell density. The subG0G1 peak was shown on the DNA histogram after A549-Tk cell was treated with 50 micromol/L GCV for 3 days by FCM, but not in the A549 cell. A cell cycle analysis showed that the apoptotic cell in the A549-TK and A549 cells were (12.2+/-1.7) % and (1.3 +/- 0.3) %, respectively (P < 0.01). The cell apoptosis features of nuclear condensation, apoptotic vesicle, and nuclear showing semimoon feature were found in the A549-TK cell by SEM, but not in the A549 cell. Recombination and expression of the TK gene were positive in the transfected cell. In vivo, the growth of tumors formed by the transfected cell was apparently inhibited by GCV, but not in the control group. CONCLUSION: The transfected cell obtained sensitivity to GCV and the bystander effect was closely related to intercellular touch. The TK/GCV system killing tumor cell was related to cell apoptosis. GCV inhibited the growth of tumors which were inoculated by A549-TK cell in vivo.

Adenocarcinoma↗
PubMed1999

Lowering of trichosanthin immunogenicity by site-specific coupling to dextran.

Trichosanthin is a type I ribosome-inactivating protein possessing a broad spectrum of biological and pharmacological activities. Therapeutic use of this compound is hampered by its immunogenicity. It was shown earlier that coupling of dextran to trichosanthin can increase plasma half-life and reduce antigenicity. However, the site where dextran attaches to trichosanthin cannot be controlled; ideally, it should be at or near the antigenic determinant. The present study attempted to couple dextran to trichosanthin at a potential antigenic site. By site-directed mutagenesis, two sites, R29 and K173, were replaced by cysteine, and dextran was coupled to the newly created cysteine residues. The dextran-trichosanthin complex retained 50% of abortifacient activity and had a mean residence time in rats 27-fold longer than natural trichosanthin. Acute hypersensitivity reaction in guinea pigs was reduced greatly after coupling of K173C (a trichosanthin mutant with lysine-173 replaced by cysteine) to dextran. Compared with natural trichosanthin, dextran-K173C had a decrease in IgG and IgE response, whereas the coupling of R29C (a trichosanthin mutant with arginine-29 replaced by cysteine) to dextran did not show significant reduction of immunogenicity. This suggests that K173 but not R29 is located at or near an antigenic determinant. This study has demonstrated an alternative approach for mapping of antigenic determinants. The information obtained is also useful in producing an improved trichosanthin derivative for therapeutic use.

Acute-Phase Reaction↗
PubMed1999

Site-directed polyethylene glycol modification of trichosanthin: effects on its biological activities, pharmacokinetics, and antigenicity.

Trichosanthin (TCS), a type I ribosome-inactivating protein (RIP), was modified with polyethylene glycol (PEG) in order to reduce its antigenicity and prolong its half-life. Computer modeling identified three potential antigenic sites namely Q219, K173 and S7. By site-directed mutagenesis, these sites were changed into cysteine through which PEG can be covalently attached. The resulting TCS had a PEG coupled directly above one of its potential antigenic determinants, hence masking the antigenic region and prevent binding of antibodies specific to this site. In general, mutation did not bring about significant changes in ribosome-inactivating activity, cytotoxicity, and abortifacient activity of TCS. However, the in vitro activities of PEG modified (PEGylated) TCS muteins were 3-20 folds lower and the in vivo activity 50% less than that of nTCS. Pharmacokinetics study indicated that all three PEGylated TCS muteins showed 6-fold increase in mean residence time as compared to unmodified muteins. The binding affinity of an IgE monoclonal antibody (TE1) to TCS was greatly reduced after PEG modification (PEGylation) at position Q219, suggesting that TE1 recognized an epitope very near to residue Q219. PEGylated TCS muteins induced similar IgG response but 4-16 fold lower IgE response in mice compared with nTCS.

Animals↗
PubMed1999

Reducing the immunogenicity and improving the in vivo activity of trichosanthin by site-directed pegylation.

PEG modification (PEGylation) has been shown to reduce immunogenicity and prolong circulating half-life of proteins. In the present study, site-directed PEGylation was used to reduce immunogenicity and prolong plasma half-life of trichosanthin (TCS). Four TCS mutants, i.e. S7C, Q219C, K173C and [K173C,Q219C] (KQ), were constructed by site-directed mutagenesis. PEG modifications were done by reacting PEG5k-maleimide or PEG20k-maleimide reagent with the newly introduced cysteine residue of the mutants. The plasma clearance rate of PEGylated TCS mutants decreased up to 100-fold and the decrease was inversely proportional to the effective molecular size. The in vitro activities such as ribosome-inactivating activity and cytotoxicity were also decreased. However, the in vivo abortifacient activity was, slightly decreased, unchanged, or even enhanced in some preparations. PEG5k modification had little effect on immunogenicity. However, PEG20k modification significantly reduced immunogenicity. All PEG20k modified TCS mutants induced lower level IgG and IgE antibodies. In particular, PEG20k-KQ and PEG20k-K173C induced weaker systemic anaphylaxis reaction in guinea pigs. In conclusion, the present results suggest that PEG20k is better than PEG5k for reducing immunogenicity and prolonging plasma half-life. The conjugate can become a better therapeutic agent.

Anaphylaxis↗
PubMed1998

Sensory nerve endings in monkey hip joint capsule: a morphological investigation.

This study was undertaken to identify the sensory nerve endings in the monkey hip joint capsule. The capsules from six monkeys were stained in bulk by using a modified gold chloride method. Three morphologically distinct nerve endings: Type I, II and IV receptors resembling Ruffini end organs. Pacinian corpuscles and free nerve endings, respectively, were identified. The results showed that the hip joint capsules were densely innervated. Based on the present findings it is suggested that the monkey hip joint capsule is endowed with several types of afferent nerve endings, thus providing the anatomical basis for discriminating afferent outflow to the central nervous system.

Animals↗
PubMed1997

Structure-function relationship of trichosanthin.

Trichosanthin (TCS), a 27 kDa ribosome inactivating protein extracted from the root tuber of Trichosanthes plant, was subjected to limited chymotrypsin digestion and three peptide fragments designated TCS-F1 72-247, TCS-F2 100-247, and TCS-F3 133-247 were generated. The RNA-N-glycosidase and cytotoxic activities of the TCS fragments were compared with that of inact TCS. TCS-F1 and TCS-F2 were biologically active, while TCS-F3 was completely inactive. Dose-dependent studies showed that TCS-F1 and TCS-F2 were less potent in their trophoblast cytotoxicity than intact TCS, however, full biological effect could still be obtained with a higher dosage. Based on the known three-dimensional structure of TCS, we postulate that the putative active site of TCS is located at amino acid residues 110 to 174.

Chymotrypsin↗
PubMed1997

Expression of NADPH-diaphorase and nitric oxide synthase in lumbosacral motoneurons after knee joint immobilisation in the guinea pig.

The expression of nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) and nitric oxide synthase (NOS) in spinal ventral horn neurons was studied in the guinea pig after right knee joint immobilisation (RKJI). At 1 wk after RKJI, neurons in the ipsilateral ventral horn from L4 to S1 segments showed a moderate reactivity for NADPH-d staining. At 2 wk, NADPH-d labelled neurons were also observed in the contralateral ventral horn. Ipsilateral NOS immunoreactive cells were not detectable until wk 2. The intensity of NADPH-d and NOS labelled neurons in the bilateral ventral horns was sustained, peaking at the 4th wk after RKJI. In guinea pigs subjected to 4 wk of RKJI and subsequently released from the immobilisation for 2 and 4 wk, NADPH-d and NOS reactivity in ventral horn neurons diminished. The expression of NADPH-d positive neurons differed from that of NOS labelled neurons in terms of time interval, cell number and staining intensity, the latter being later, fewer and weaker. It is suggested that the induction and upregulation of NADPH-d and NOS are attributable to reduced activity of muscles acting on the knee joint after RKJI; the changes are reversible. It is speculated that increased levels of NO production are involved in protective mechanisms against possible neuronal degeneration as a consequence of target dysfunction.

Animals↗
PubMed1994

Vitamin K-dependent protein S in Leydig cells of human testis.

Protein S is an anticoagulant plasma protein, functioning as a cofactor to activated protein C in the regulation of blood coagulation. In addition, protein S forms a complex with the complement regulatory protein, C4b-binding protein. Protein S is unique among the vitamin K-dependent proteins in being structurally similar to androgen binding proteins. Protein S immunoreactivity was demonstrated in Leydig cells of human testis. In Northern blotting experiments, the presence of protein S mRNA in human testis tissue could be shown. In situ hybridization experiments localized protein S mRNA to the Leydig cells, demonstrating transcription of the protein S gene in these cells. Five protein S clones were isolated from a human testis cDNA library, partially sequenced and characterized by restriction enzyme mapping. Three unique clones contained information for the entire coding sequence and approximately two-thirds of the 5' and 3' non-coding sequences. The results indicate the nucleotide sequences of testis and liver protein S mRNA to be identical. No binding of androgens to protein S could be demonstrated. In conclusion, we demonstrate the presence of protein S immunoreactivity as well as protein S mRNA in the Leydig cells of human testis. These results suggest local synthesis of protein S in Leydig cells of human testis which may be functionally important for local anticoagulation.

Base Sequence↗
PubMed1990

[Prognosis of severe organic phosphorus pesticide intoxication and the effect of atropine treatment: analysis of 506 cases].

The results of atropine treatment in 506 cases of severe organic phosphorus pesticide intoxication are reported. Among the variables which might effect the results of treatment, the average dosage of atropine was related intimately to the prognosis (standard coefficient of regression bi = 0.4702, P less than 0.01). When the average drug dosage was 40-80 ng/h, the mortality was 26.6% and much lower than other groups (P less than 0.01). Intravenous administration given at regular intervals was better than continuous drip; the mortality dropped to 61.2% from 90.9% (P less than 0.01). Both inadequate atropinization and atropine intoxication were less frequently seen during intermitten injection (P less than 0.01).

Adolescent↗
PubMed1990

[Analysis of 1355 cases of tumors and tumor-like lesions in the bone].

A total of 1355 cases of tumors and tumor-like lesions in the bone seen in the three hospitals affiliated to our college in the past 32 years was analysed. Of them, 1170 (86.4%) were primary bone tumors, 31 (2.3%) metastatic and 154 (11.3%) tumor-like lesions of bone. Histologically, the primary bone tumors were mostly chondrogenic and osteogenic. The ratio of benign to malignant tumors was 2.8:1. Peak ages were 11-40 years. Patients with malignant tumors were ten years younger than those with benign tumors. The first three common benign bone tumors were osteochondroma, osteoma and chondroma. The vulnerable sites were tibia, femur and skull. The first three common malignant bone tumors were osteosarcoma, chondrosarcoma and fibrosarcoma with common sites in femur, tibia and humerus. The majority of tumor-like lesions were fibrous-dysplasia, frequently in the femur. These observations are very similar to those reported at home but quite different from those reported from other countries. In our series, the ratio of benign to malignant bone tumors was the highest (2.8:1); giant cell tumor was not among the first three common benign bone tumors; and the first vulnerable site of benign bone tumors was not femur but tibia.

Adolescent↗
PubMed1986

Longterm auranofin therapy in patients with juvenile rheumatoid arthritis.

Auranofin (AF, Ridaura) was administered to 23 children with juvenile rheumatoid arthritis during a prospective, open labelled, noncontrolled trial designed to establish longterm safety and preliminary efficacy. Dosages of AF were up to 0.2 mg/kg/day, with either aspirin (60-80 mg/kg/day), naproxen (400-600 mg/m2/day), or tolmetin sodium (20-40 mg/kg/day) serving as the concurrent nonsteroidal antiinflammatory drug. Nearly all patients showed an initial favorable response, however tachyphylaxis occurred in one-third (mean duration of therapy prior to the development of inefficacy = 22.6 mo). Clinical remission was observed in 6 patients an average of 15 months after enrollment. The drug appears to be safe for extended periods; 7 children are continuing AF at the present time with a mean duration of therapy of 4.25 years (maximum followup = 4.6 years).

Adolescent↗