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Biomedical subjects

S X Liu

Publications and source records attributed to S X Liu.

At least 73 records · Page 4Linked to original sources
PubMed1995

Feasibility of glucagon eyedrops for clinical use in hypoglycemia.

Although sufficient amount of glucagon can be taken up into systemic circulation through ocular route, the concentration of eyedrops needed at 7.5% would be too high and the price of the doses would be too expensive to be desirable. Attempts have been made to reduce the doses of glucagon needed for systemic delivery through ocular route by adding absorption enhancers such as 0.5% BL-9 or 0.5% Brij-78. With these absorption enhancers, the effective concentrations of glucagon eyedrops can be lowered to 0.05% in rabbit eyes and could be lowered to 1.25% in human eyes which would be reasonable to be used in the clinics.

Absorption↗
PubMed1995

Anti-fecundity immunity induced in pigs vaccinated with recombinant Schistosoma japonicum 26kDa glutathione-S-transferase.

We have recently reported (Liu et al. 1995) that immunization of mice with recombinant 26kDa GST (reSjc26GST) induces a pronounced anti-fecundity effect after experimental infection with Chinese Schistosoma japonicum. A similar vaccination trial was thus carried out on pigs, important reservoirs for schistosomiasis japonica, using purified, reSjc26GST and reSjp26GST from Schistosoma japonicum with alum as adjuvant; in general, similar results were obtained with the two sources of recombinant 26kDa GST. Some protection in terms of worm reduction, significant with males, against challenge infection was observed in vaccinated pigs. Moreover, prior to challenge, levels of specific anti-re26GST antibodies in the vaccinated pigs were significantly higher than in non-vaccinated pigs as determined by GST-ELISA. The most striking feature of the vaccine trial was the significant reduction in the number of eggs, especially mature eggs, in the livers of vaccinated animals. The results indicate that immunization with recombinant Sj26GST can provide some reduction in worm burden following exposure of pigs to reinfection with S. japonicum. In addition, reSj26GST can induce an anti-fecundity effect, thereby reducing pathology, coupled with a delay or interruption of the development of immature to mature eggs in the liver. As a consequence, vaccination with Sj26GST would also prove useful in affecting the transmission of schistosomiasis japonica.

Animals↗
PubMed1995

[Effect of microinjection of sodium giutamate and glycine into ventrolateral nucleus of tractus solitarius on the evoked potentials of arcuatus nucleus in rabbits].

Experiments were performed on 66 anaesthetized, vagotomized, paralyzed and artificially ventilated rabbits. The effects of microinjection sodium glutamate and glycine into ventrolateral nucleus of tractus solitarius (VLNTS) on hypothalamic arcuatus nucleus evoked potentials were observed. The main results obtained were as follows: (1) Phrenic nerve discharges were increased and the amplitude of P2 and N2 waves of arcuatus nucleus evoked potentials were decreased by microinjection of sodium glutamate into VLNTS. Phrenic nerve discharges were decreased and the amplitude of P2 and N2 waves of arcuatus nucleus evoked potentials were increased by microinjection of glycine into VLNTS. (2) After intravenous injection of naloxone, the phrenic nerve discharges could still be excited by microinjection of sodium glutamate as before, but the effects on the amplitude of P2 and N2 waves of arcuatus nucleus evoked potentials, unlike that of sodium glutamate, were reversed. The results suggest that the excitatory action of respiratory neurons in the VILTS may affect on the sensory function of arcuatus nucleus. The mechanism involved was discussed.

Animals↗
PubMed1994

Feasibility of insulin eyedrops for human use.

To determine the minimum effective concentration of insulin eyedrops for human use, insulin eyedrops at 0.01%, 0.05%, and 0.25% plus 0.5% Brij-78 were instilled into rabbit eyes. Brij-78 (0.5%) eyedrops were instilled as control. It was found that very low concentrations of insulin such as 0.05% plus 0.5% Brij-78 can reduce the blood glucose effectively in rabbits. The 0.05% insulin with 0.5% Brij-78 seems to be the best choice. Assuming the human body weight is approximately 25 times that of the rabbit, the concentration of insulin to be used for human patients would be 1.25% insulin (0.05% x 25), which is equivalent to 1.25 mg insulin/75 kg body weight. Because the absorption rate of insulin eyedrops plus Brij-78 is approximately 60-70%, 1.25% insulin plus Brij-78 would easily reach the therapeutic dose of insulin by injection (0.4-0.5 mg/75 kg). These results indicate that it is feasible to use insulin eyedrops to lower the blood glucose in humans. There was no statistical difference in blood glucose levels between animals instilled with 0.5% Brij-78 alone as control and those instilled with 0.01% insulin plus 0.5% Brij-78.

Absorption↗
PubMed1994

Effects of increased expression of protein kinase C on radiation-induced cell transformation.

The in vitro oncogenic transformation of C3H 10T1/2 cells by ionizing radiation is known to be enhanced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). It is also known that the activation of protein kinase C (PKC) by TPA is an important step in its tumor-promoting effect. In the present study, we examined the effects of overexpression of a specific isoform of PKC, PKC beta 1 on gamma-ray-induced transformation of 10T1/2 cells. In addition, the effects of overexpression of PKC beta 1 on the malignant phenotype of a previously transformed 10T1/2 cell line were also evaluated. Derivatives of 10T1/2 cells that stably overexpress PKC beta 1 were obtained by transduction with the retroviral expression vector pMV7 carrying the rat PKC beta 1 cDNA sequence. We found that the parental 10T1/2 cells and a control cell line 10T1/2 MV7, which carried only the pMV7 vector without the cDNA insert, expressed dose-dependent transformation frequencies when exposed to gamma-rays. On the other hand, concurrently treated PKC-overexpressing cells that had an 11-fold increase in enzyme activity (PKC-4 cells) failed to yield any morphologically identifiable foci. Cell lines that expressed lower levels of PKC beta 1 were partially resistant to transformation by gamma-rays. Clonogenic survival data indicated that this observation was not due to radioresistance per se. Thus, overexpression of PKC beta 1 did not appear to function as an endogenous substitute for TPA in promoting radiation-induced transformation. Furthermore, overexpression of PKC did not reverse the transformation phenotypes in tumorigenic 10T1/2 cells once it was established. These findings are discussed with respect to the specific roles of individual isoforms of PKC in growth control.

Animals↗
PubMed1994

[A study on changes of plasma endothelin-1 level in patients with chronic cor pulmonale].

The level of plasma endothelin-1 (ET-1) was measured with radioimmunoassay in 36 patients with chronic pulmonale before and after treatment. The results showed that ET-1 level was significantly higher in cor pulmonale patients (P < 0.001) and decreased significantly after treatment (P < 0.001), but was still higher than that in controls (P < 0.002). There was significant negative correlation between PaO2, pH and ET-1 level. A significant positive correlation was found between ET-1 level and PaCO2. The results suggest that ET-1 may play an important role in the pathophysiological process of chronic cor pulmonale and the drugs which can influence plasma ET-1 level may be used in the treatment of the disease.

Aged↗
PubMed1994

[Biological characteristics of Ligusticum chuanxiong Hort].

Observational studies were conducted on the biological characteristics of Ligusticum chuanxiong, such as suitable growth environment, growing period, growth of stems, leaves and rhizomes, yield structure, etc. The specific regularities of each growth period were also studied.

Plants, Medicinal↗
PubMed1993

[Reconstruction of large performated maxillofacial defect with immediated revascularized flap]

Patients with large perforated maxillofacial defects resulting from combined craniomaxillofacial resection or extended extra cranio-maxillofacial resection due to malignances in this region had been reconstructed with large revascularized myocutaneous flap or combined pedicled myocutaneous flap with revascularized flap.Since January,1981,a total of 29 flaps was used,of which 28 flaps survived successfuly,whereas one free forearm flap being failed to survive due to venous embolization was replaced with pedicled forehead flap.The results in postoperative appearance and rehabilitation of physiological function were relatively satisfactory.Finally,selection of flap and method of reconstruction were introduced and experiences on immediate reconstruction after malignance resection reported.

Journal Article↗
PubMed1993

The temperature--dependent expression of GST of Schistosoma japonicum (Philippine strain).

Obtained from pSj5, the cDNA gene encoding GST antigen of Schistosoma japonicum (Philippine strain) was ligated with efficient temperature-dependent PBV220 vector which was constructed in CAPM, and then introduced into host bacterium-DH5 alpha (E. coli) by transformation. Transformants were selected by ampicillin and recombinant clones were identified by restriction mapping. The result showed that recombinant clone 43 was the one carrying recombinant plasmid PBV 220 with the correct insertion of the gene fragment. The GST expression ability of clone 43 was investigated by GST enzymic activity assay and SDS-PAGE. A relatively high level of GST enzymic activity was expressed by this clone under the temperature-dependent condition, that is, cultured at 30 degrees C and expressed at 42 degrees C. A more strongly stained 26 kDa protein band was identified by SDS-PAGE. The result indicated that GST of S. japonicum (Philippine strain) could be expressed not only by IPTG induction, but also by the temperature-dependent method.

Animals↗
PubMed1993

The antigenicity of GST antigen extracted from Chinese strain of Schistosoma japonicum.

The GST antigen, similar to Sj26 (Philippine strain), which plays an important role in inducing protective immunity against Schistosoma japonicum, can be extracted and purified from adult worms of the Chinese strain of S. japonicum. There are two bands at 26 kDa and 28 kDa of GST antigen called the 26-28 kDa GST antigen as identified by SDS-PAGE, and these have GST activities. Mice were immunized with the 26-28 kDa antigen and the specific antibody response in serum was assayed by ELISA, IFA and western blot. The antigenicity of the 26-28 kDa GST antigen in mice was significant. For example, the antigen could stimulate mice to increase the level of serum IgM and IgGl; the antibodies in serum of immunized mice could be localized in the antigenic determinants of tegument or body of the worms; specific antibodies against the antigens increased markedly after immunization as measured by ELISA or IFA; the antibody from mice immunized with the 26-28 kDa GST antigen can recognize 26-28 kDa antigenic molecules, identified by immunoblot assay.

Animals↗
PubMed1993

Comparative study on antigenicity and immunogenicity of 26-28 kDa antigen and recombinant Sj26 (RSj26) of Schistosoma japonicum.

This paper reports a comparison of the recombinant Sj26 (rSj26) antigen derived from the Philippine strain and the 26-28 kDa antigen isolated and purified from the Chinese strain of Schistosoma japonicum with respect to their antigenicity and immunogenicity. The results showed that there were obvious cross reactions between rSj26 and 26-28 kDa antigen when rSj26 antigen was tested against specific antibodies in sera of mice infected with the Chinese strain of S. japonicum or the 26-28 kDa antigen was tested against specific anti-rSj26 antibodies by ELISA, IFA and Western blotting. Both the 26-28 kDa and the rSj26 antigen had weak cross reactions with SEA antigen. The worm reduction rate after challenging with Chinese strain cercariae in mice immunized with rSj26 was 26-32%, similar to that in mice immunized with 26-28 kDa antigen. It is suggested that rSj26 antigen can induce a certain level of specific protective immunity in the host against infection by the Chinese strain of S. japonicum cercariae.

Animals↗
PubMed1993

The possibility of GST antigen from Chinese strain of Schistosoma japonicum for immunodiagnosis of schistosomiasis.

The GST antigen (called 26-28 kDa antigen) extracted and purified from Schistosoma japonicum adult worms was applied to the detection of specific antibodies in sera of infected mice and mice immunized with the above protein antigen by ELISA technique. The 26-28 kDa antigen was better than crude antigens (SEA, SWAP) when used to detect specific antibodies in sera from immunized mice. As with crude antigens (SEA and SWAP), the 26-28 kDa antigen could be used to detect specific antibodies in infected sera, with titers as high as 1:160-1:320. There were no false positive reactions and a positivity rate as high as that using SWAP occurred when the 26-28 kDa antigen was used in schistosomiasis patients and normal subjects by intradermal test. It is suggested that the 26-28 kDa antigen may be a suitable candidate for immunodiagnosis of schistosomiasis.

Animals↗
PubMed1993

[Test of colonic transit for the diagnosis of constipation].

This study consists of the design of the experimental markers for the colonic transit and the application of clinical examination. The markers were displayed distinctly in the transit test. The study of clinical application showed that colonic transit test is of diagnostic value in screening patients with constipation. The index of transit test, an authoritatively significant target, is an important value for the differential diagnosis of patients with constipation. We conclude that multiple physiological examinations are the key to the successful operation and strict indications are necessary for the surgical treatment of constipation.

Adult↗
PubMed1993

Stress analyses after femoral shaft osteotomy fixed by various plates with different rigidities in simulation test.

Three pairs of human cadaver femora were used for strain measurement under a weight-bearing simulation test, which was performed on intact bone and osteotomized bone fixed by 3 types of plates with different rigidities respectively. The plates with uniform thickness did not adhere to the uniform stress distribution along the plate. The stress between both central screw holes was significantly great. However, the device of trapezoidal plate conformed to the uniform stress distribution along it, and the safety factors of 3 different types of the plates were proposed. The osteotomy site was mainly subjected to compression stress in standing phase with load on both femora, but subjected to bending stress mostly with load on the single femur. The total compression strain at the osteotomy site was greater than that on intact bone while the load was adding over twice body weight with load on both legs, and nearly normal with load on one leg. We believe that the bone structural changes caused by stress shielding and limb disuse etc can be overcome by using optimal plate and normal weight bearing.

Bone Plates↗
PubMed1992

[Comparative study on antigenicity and immunogenicity of the 24-26 kDa antigen and the recombinant Sj26 antigen of Schistosoma japonicum].

This paper reports on the comparison of the recombinant Sj26 (rSj26) antigen originated from the Philippine strain and 24-26 kDa antigen isolated and purified from Chinese mainland strain of S. japonicum for their antigenicity and immunogenicity. The results showed that there were obvious cross reactions between rSj26 and 24-26 kDa antigen when rSj26 antigen was tested against specific antibodies in sera from mice infected with the mainland strain of S. japonicum or 24-26 kDa antigen was tested against specific anti-rSj26 antibodies by ELISA, IFA and Western blotting etc. Both of 24-26 kDa and rSj26 antigen had weak cross reaction with SEA antigen. The worm reduction rate after challenging with mainland strain cercariae in mice immunized with rSj26 was 26-32%, similar to that in mice immunized with 24-26 kDa antigen. It is suggested that rSj26 antigen can induce certain level of specific protective immunity to protect the host against infection by Chinese strain of S. japonicum cercaciae.

Animals↗
PubMed1992

An overview of molecular parasitology in China.

Molecular cloning technology has been gradually used in the studies of parasitic diseases in China since 1986. The information briefly reviewed here deals mainly with: (1) the molecular cloning of immunogen genes related to Schistosome and Plasmodium; (2) a diagnostic DNA probe for malaria and toxoplasmosis; and (3) DNA probes for inter- and intra-specific differentiation of Leishmania, Schistosome, Entamoeba, etc.

Animals↗