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Biomedical subjects

S Cai

Publications and source records attributed to S Cai.

At least 145 records · Page 8Linked to original sources
PubMed1998

Blood volume redistribution on fluid treatments after burn-blast combined injury, especially with respect to the regulation role of microcirculation due to the Fåhraeus effect.

Considering the Fåhraeus effect and the blood volume regulation role of the microcirculation, we used a new method for calculating the blood volume change in microcirculation, macrocirculation as well as the whole circulation (delta Vmic, delta Vmac, delta Vb), to compare fluid therapy effects of hypertonic saline dextran solution (HSD) and lactic Ringer's solution at the early stage after burn-blast combined injury (BBI). The measurement of plasma viscosity was used in this calculation. The results showed that, with calculation of the blood volume change in microcirculation and macrocirculation, this method could more exactly and distinctly display the change and distribution of blood volume during the therapy. It confirms that HSD treatment can increase blood pressure and attenuate tissue edema, by significantly increasing total blood volume, recouping delta Vmac. The study suggests that a desirable and practical clinical method for blood volume change can be developed based on the present study.

Animals↗
PubMed1997

Effects of thiol-modifying agents on a K(Ca2+) channel of intermediate conductance in bovine aortic endothelial cells.

Ca2+-activated K+ channels (K(Ca2+)) constitute key regulators of the endothelial cell electrophysiological response to InsP3-mobilizing agonists. Inside-out and outside-out patch clamp experiments were thus undertaken to determine if the gating properties of a voltage-insensitive K(Ca2+) channel of intermediate conductance present in bovine aortic endothelial (BAE) cells could be modified by specific sulfhydryl (SH) oxidative and/or reducing reagents. The results obtained first indicate that cytosolic application of hydrophilic oxidative reagents such as 5,5'-dithio-bis(2-nitrobenzoic acid) (DTNB) (0.2 to 5 mM) or [(O-carboxyphenyl)thio]ethyl mercury sodium salt (thimerosal) (0.5 to 5 mM) reduces gradually the K(Ca2+) channel activity with no modification of the channel unitary conductance. The inhibitory action of DTNB (1 to 5 mM) or thimerosal (1 to 5 mM) was not reserved following withdrawal of the oxidative agents, but channel activity could partly be restored by the addition of the SH group reducing agents dithiothreitol (DTT) (5 mM) or reduced glutathione (GSH) (5 mM) in 53% and 50% of the inside-out experiments performed with DTNB and thimerosal respectively. Similar results were obtained using H2O2 at concentrations ranging from 500 microM to 10 mm as oxidative reagent. In contrast, the lipid soluble oxidative agent 4,4'-dithiodipyridine (4-PDS) (1 mM) appeared in inside-out experiments less potent than DTNB and thimerosal at inhibiting the K(Ca2+) channel activity, suggesting that the critical SH groups involved in channel gating are localized at the inner face of the cell membrane. This conclusion was further substantiated by a series of outside-out patch clamp experiments which showed that DTNB (5 mM) and thimerosal (5 mM) were unable to inhibit the K(Ca2+) channel activity when applied to the external surface of the excised membrane. Finally, no significant changes of the gating properties of the K(Ca2+) channel were observed in inside-out experiments where the SH group reducing agents DTT and GSH were applied immediately following membrane excision. However, the application of either GSH or DTT was found to partly restore channel activity in experiments where the K(Ca2+) channels showed significant rundown.

Animals↗
PubMed1997

Biological monitoring of cadmium exposure and renal effects in a population group residing in a polluted area in China.

In an area of China, not previously studied in detail concerning cadmium pollution and possible adverse effects on the kidney of exposed populations, concentrations of cadmium in urine as an indicator of renal accumulation of cadmium was studied and related to indicators of renal dysfunction in order to examine if a relationship could be documented. Cadmium concentrations in urine were analysed by graphite furnace atomic absorption spectrometry and urinary beta-2 microglobulin (UBM) and albumin (UALB) were measured as indicators of renal dysfunction, Rice samples and urine samples were obtained from three areas in Zhejiang province, China, representing a highly exposed area, a medium exposed area and a control area, respectively. Cadmium concentrations in rice were 3.70, 0.51 and 0.072 mg/kg for the heavily, medium polluted areas and the control area, respectively. Cadmium concentrations in urine (geometric means) were 10.7, 1.62 and 0.40 micrograms/l in the high, medium and control areas respectively. There was a clear increase in UBM and UALB in the heavily exposed group in comparison to the control group and a slight increase in the medium exposed group. There was a statistically significant dose-response relationship between cadmium in urine and beta 2-microglobulin excretion in urine, which is similar to what has previously been reported in other countries. The findings constitute the first report concerning a dose-response relationship in this population group in Zhejiang province in China.

Adult↗
PubMed1997

Regulation of cell motility by mitogen-activated protein kinase.

Cell interaction with adhesive proteins or growth factors in the extracellular matrix initiates Ras/mitogen-activated protein (MAP) kinase signaling. Evidence is provided that MAP kinase (ERK1 and ERK2) influences the cells' motility machinery by phosphorylating and, thereby, enhancing myosin light chain kinase (MLCK) activity leading to phosphorylation of myosin light chains (MLC). Inhibition of MAP kinase activity causes decreased MLCK function, MLC phosphorylation, and cell migration on extracellular matrix proteins. In contrast, expression of mutationally active MAP kinase kinase causes activation of MAP kinase leading to phosphorylation of MLCK and MLC and enhanced cell migration. In vitro results support these findings since ERK-phosphorylated MLCK has an increased capacity to phosphorylate MLC and shows increased sensitivity to calmodulin. Thus, we define a signaling pathway directly downstream of MAP kinase, influencing cell migration on the extracellular matrix.

Animals↗
PubMed1997

The importance of MHC-I and MHC-II responses in vaccine efficacy against lethal herpes simplex virus type 1 challenge.

To investigate the importance of major histocompatability complex (MHC) class I- and MHC class II-dependent immune responses in herpes simplex virus-1 (HSV-1) vaccine efficacy, groups of beta 2% (MHC I-) and Ab% (MHC II-) mice were inoculated with various vaccines, and then challenged intraperitoneally with HSV-1. Following vaccination with either live avirulent HSV-1, expressed HSV-1 glycoprotein D (gD), or a mixture of seven expressed HSV-1 glycoproteins (7gPs), Ab% (MHC-II-) mice developed no enzyme-linked immunosorbent assay (ELISA) or neutralizing antibody titres. In contrast, significant ELISA and neutralizing antibody titres were induced in beta 2m% (MHC-I-) mice by all three vaccines. The neutralizing antibody titres were similar for all three vaccines, but were only approximately 1/4 to 1/3 of that developed in C57BL/6 (parental) mice vaccinated with the same antigens. All three vaccines protected 100% of the wild-type C57BL/6 mice against lethal challenge with 2 x 10(7) plaque-forming units (PFU) of HSV-1. The live virus vaccine and the 7gPs vaccine also protected 80% of the beta 2m% mice against the same lethal HSV-1 challenge dose. In contrast, in Abo/o mice, none of the vaccines provided significant protection against the same lethal challenge dose of HSV-1. However, at a lower challenge dose of 2 x 10(6) PFU, all three vaccines protected 70-80% of the vaccinated Ab% mice (compared to only 10% survival in mock vaccinated controls). Thus, vaccination provided some protection against lethal HSV-1 challenge in both beta 2m% and Ab% mice; however, the protection was less than that seen in the parental C57BL/6 mice. In addition, Ab% mice were less well protected by vaccination than were beta 2m% mice. Our results suggest that (1) both MHC-I and MHC-II are involved in vaccine efficacy against HSV-1 challenge; (2) both types of responses must be present for maximum vaccine efficacy: and (3) the MHC-II-dependent immune response appeared to be more important than the MHC-I-dependent immune response for vaccine efficacy against HSV-I challenge.

Animals↗
PubMed1997

MHC-II but not MHC-I responses are required for vaccine-induced protection against ocular challenge with HSV-1.

PURPOSE: To determine the importance of major histocompatibility complex (MHC) class-I versus MHC class-II immune responses in protecting naive versus vaccinated mice against an ocular HSV-1 challenge. METHODS: Class-II deficient A beta o/o (CD4-CD8+ T cells) knockout mice, which are effectively CD4+ T cells-negative, and class-I deficient beta(2)mo/o (CD4+CD8- T cells) knockout mice, which are effectively CD8+ T cells negative, were either vaccinated or mock-vaccinated and examined for their ability to withstand HSV-1 ocular challenge. RESULTS: Unvaccinated A beta o/o and beta(2)mo/o mice were both more susceptible to lethal ocular HSV-1 infection than the parental wild type C57BL/6J mice, indicating that both MHC-I and MHC-II were required for optimal protection of naive mice against ocular HSV-1 challenge. Vaccinated beta(2)mo/o mice produced significant neutralizing antibody titers, and following ocular challenge, these mice were completely protected against death and corneal scarring. In contrast, vaccinated A beta o/o mice developed no neutralizing antibody titers and vaccination did not provide these mice with any protection against death or corneal scarring. Passive transfer of anti-HSV-1 antibody into A beta o/o mice up to 6 days post ocular challenge resulted in complete protection against death and corneal scarring. CONCLUSIONS: Passive antibody transfer, but not vaccination, protected A beta o/o mice against ocular challenge. In contrast, vaccination completely protected beta(2)mo/o mice. These results suggest for a vaccine to provide optimal protection against ocular HSV-1 challenge in this system, it is not only sufficient, but it is also required, that the vaccine induce an effective neutralizing antibody response.

Animals↗
PubMed1997

Environmental regulation of fimbrial gene expression in Porphyromonas gingivalis.

Porphyromonas gingivalis fimbriae are an important virulence factor involved in attachment and invasion. Fimbrillin, encoded by the fimA gene, is the major subunit protein of the fimbriae. To elucidate the influence of environmental signals on the expression of the fimA gene, a strain of P. gingivalis (designated PLE) containing a chromosomal transcriptional fusion between a promoterless lacZ gene and the fimA promoter region was constructed. Promoter activity was assessed by measurement of beta-galactosidase activity of PLE. An 11-fold increase in activity of fimA promoter was found as growth temperature declined from 39 to 34 degrees C. Promoter activity decreased by approximately 50% in response to hemin limitation and upon culture on solid medium. In addition, the presence of serum or saliva in the growth medium decreased fimA promoter activity by similar amounts. A correlation between fimA promoter activity and phenotypic properties dependent upon fimbriae was established. P. gingivalis grown at 34 degrees C, compared to 39 degrees C, showed an increased ability to adhere to Streptococcus gordonii and to invade primary cultures of gingival epithelial cells. These studies indicate that expression of the P. gingivalis fimA gene is regulated at the transcriptional level in response to several environmental conditions and that altered fimA expression can also modulate the adherence and invasion abilities of P. gingivalis.

Bacterial Proteins↗
PubMed1997

[Changes of K+ channel behaviors in airway smooth muscle from asthmatic guinea-pigs].

OBJECTIVE: To observe asthma-induced changes of single K+ channel behaviors in acutely dissociated airway smooth muscle of guinea-pig. METHODS: The resting membrane potential (MP) was measured in whole-cell recording configuration. The elementary currents flowing through single K+ channel were recorded in cell-attached patches. RESULTS: The properties in asthmatic group were as follows: (1) MP was decreased from -70.3 +/- 3.5 mV to -62.8 +/- 5.6 mV. (2) In the same depolarization conditions, the amplitudes of currents decayed and conductant values were decreased with significantly difference (about 51%) from the values obtained from the control group. (3) Open time constants of fast- and slow-open states shortened markedly to 25% and 7% of controls respectively. Shut time constants were prolonged. (4) Open probability showed voltage-dependence and was decreased in the same voltage range. CONCLUSIONS: Asthmic airway hyperreactivity-related kinetic properties of K+ channel deficits, which may result a reduced threshold of excitation.

Animals↗
PubMed1997

[Effects of K+ channel openers on voltage-dependent K+ channel behavior in airway smooth muscle of guineapig].

In order to determine whether the K+ channel openers (PCOs), which are suggested to open K+ channels and to relax bronchial smooth muscle, would directly activate voltage-dependent K+ channels, single channel currents were studied on cell-attached and inside-out patches of smooth muscle acutely dissociated from bronchi of guinea-pig. The resting membrane potentials measured in whole-cell recording configuration showed no difference with control when cromakalim and lemakalim were applied extracellularly, which, however increased the conductance values of K+ channels with depolarization from 75.2 +/- 5.1 pS to 85.9 +/- 11.8 pS and 82.1 +/- 5.5 pS, respectively. The channels kinetics were also affected by PCOs. Mean open time (tau o) and open probability increased, in which the effects of lemakalim was stronger than that of cromakalim. Both PCOs elicited the multichannel activities in some patches. It is suggested that PCOs could evoke K+ channels with depolarization and stimulate K+ efflux, which may affect the excitability of muscle cells.

Animals↗
PubMed1997

[Investigation on nitrosamines in the diets of the inhabitants of high-risk area for esophageal cancer in the southern China and analysis of the correlation factors].

Nan'ao County in Guangdong Province was an esophageal cancer high-risk area in the southern China. Of the suspected etiological factors in the environment, N-nitrosamines and their precursors have been received the most attention. 55 samples of the diets ingested by the inhabitants were collected and tested for volatile N-nitroso compounds and for their precursors by GC-TEA. Five kinds of N-nitrosamines (NDMA, NDEA, NPYR, NPIP and NMBzA) were detected in the samples. The average level of them was 312.0 micrograms/kg(median). The day intake of the nitrosamines was 286.5 micrograms/head/day. By the computerized stepwise regression analysis and curve fitting, we studied the correlation among the nitrosamines, the precursors and the major food items. It demonstrated that a relatively high content of volatile N-nitrosamines was present in the diets collected in the area.

Carcinogens↗
PubMed1997

[Antiallergic effects of tranilast in rats and guinea pigs].

Tranilast is an anti-allergic drug. In this study, we made a comparision between the Tranilast synthized by School of Pharmacy WCUMS using new technical and the Tranilast produced by Kissei pharmaceutical Co. LTD, Japan on their antiallergic effects. We found that the two tranilasts had the same antiallergic effects: (1) they inhibit the passive cutaneous anaphylaxis in sensitized rats with the dose of 100, 200 mg/kg(P < 0.01); (2) they inhibit degranulation of mast cells in sensitized rats (10(-5) and 10(-4) mol/L) (P < 0.05); (3) they inhibit schultz-Dale response in sensitized guinea pigs (10(-3) and 10(-4) (mol/L); (4) the inhibit SRS-A release from the lung of sensitized guinea pigs(10(-3), 10(-4) and 10(-5) mol/L) (P < 0.05); and (5) they inhibit the contraction of ileum of normal guinea pigs induced by SRS-A(10(-4) and 10(-3) mol/L).

Animals↗
PubMed1997

[Significance of c-erbB-2 and PCNA expression in adenocarcinoma of uterine cervix].

OBJECTIVE: Significance of c-erbB-2 and PCNA expression in adenocarcinoma. METHODS: Expression of c-erbB-2 and PCNA in 74 cases of adenocarcinoma of the uterine cervix was examined by immunohistochemistry. RESULTS: The expression of c-erbB-2 was detected in 34 cases. The positive staining of c-erbB-2 was associated with increased lymph node metastasis (57.1% Vs 24.0%, P = 0.041) and lower 5-year survival rate (32.4% Vs 58.9%, P = 0.008). The average PCNA labelling index (PCNALI) was 40.6% (0.1%-91.4%). High PCNALI was associated with lymph node metastasis (56.4% Vs 38.5%, P = 0.016) and lower 5-year survival rate (28.7% Vs 64.4%, P = 0.005). Positive staining of c-erbB-2 were associated with high PCNALI (44.7% Vs 34.6%, P = 0.003). CONCLUSION: c-erbB-2 and PCNALI were associated with malignant biological behavior and poor prognosis. They may be potential prognostic factors in cervical adenocarcinoma.

Adenocarcinoma↗
PubMed1997

[Materials using in the prevention of scar formation after laminectomy].

The recurrent syndrome after laminectomy is related to the scar formation overlying epidural. To solve this catastrophic problem means to prevent the fibrosis. In the present review a variety of materials used in the inhibition or prevention of that syndrome are introduced, and their effects are reviewed and discussed. Some characteristics of the materials for prevention are summarized, and in our experiments the material point of view is rational.

Animals↗
PubMed1997

[The recent advances in the study of dendritic cells and induction of donor antigen-specific T cell tolerance].

The induction of donor antigen specific T cell tolerance will be one of the effective treatment for overcoming rejection and improving the alive quality of long-term recipients. It is increasingly noted that dendritic cell may play a two way regulation role in the balance between transplantation rejection and tolerance as the advances of knowledge of dentritic cell maturation stages. This review will focus on the recent advances in the relation between dendritic cell and induction of donor antigen specific tolerance; its mechanism and potential therapeutic application in transplantation.

Animals↗
PubMed1997

[The prospective study of the influence of cytomegalovirus (CMV) infection of pregnant women to fetus].

Screening of CMV infection in 450 pregnant women in Shenyang was carried on by ELISA and PCR methods, and CMV infection was detected in 100 of their infants prospectively. The results were 97.11% of pregnant women with past infection, 0.89% with primary infection, 11.11% with recurrent infection, only 2% were susceptible. From 450 pregnant women, there were 3 infants with congenital defects and 3 abortions in active infective group, who were positive for IgM antibody, CMV DNA were positive in heparin peripheral blood, cervical secretion, placenta or amnionic fluid. The fetal infection rate and congenital defect rate in infective group were higher than that in inactive control group. Within 100 maternal-infant pair group, congenitally infected infants were 1.43 times higher in infective group than that in control group (RR = 1.43). Two infants with mental retardations (MDI<70) were born in infective group, but none in control group. In our study, primary infection of early pregnancy was most harmful to fetus, the intrauterine transmission rate was 33.3%. Among nine infected infants born from the infective group, two infants were with CID, and seven were symptomless. CMV screening is important for pregnant women in view of eugenic. When active CMV infection is found in early pregnancy, termination of pregnancy is better considered while CMV detection of amniotic fluid is also positive.

Adult↗
PubMed1997

[Spectrophotometric studies on and applications of the reaction of copper with 2-hydroxy-3-carboxy-5-sulfobenzenediazoaminoazobenzene].

A highly sensitive color reaction of copper(II) with 2-hydroxy-3-carboxy-5-sulfobenzenediazoaminoazobenzene (HCSDAA) in the presence of Triton N-101 was studied in detail. In borax buffer medium at pH 10.4-11.5, the red complex formed has a maximum absorption at 530 nm and its apparent molar absorptivity is 1.31 x 10(5)L x mol(-1) x cm(-1) and sandell sensitivity is 4.85 x 10(-4) microg x cm(-2). The molar ratio of copper(II) to HCSDAA in the complex is found to be 1:2. Beer's law is obeyed in the concentraction range of 0-0.24 microg/mL for copper. The proposed method has been applied to the spectrophotometric determination of microamounts of copper in ore and peanut with the relative error and the relative standard deviation (n = 6) of less than 3.7% and 1.6%, respectively.

English Abstract↗
PubMed1997

Nonneutralizing antibody against the glycoprotein K of herpes simplex virus type-1 exacerbates herpes simplex virus type-1-induced corneal scarring in various virus-mouse strain combinations.

PURPOSE: To determine whether the exacerbation of herpes simplex virus type-1 (HSV-1) induced corneal scarring that the authors reported previously in HSV-1 glycoprotein K (gK) vaccinated BALB/c mice challenged with HSV-1 strain McKrae was a general phenomenon independent of virus and mouse strains. To determine the gK-induced immune response leading to exacerbation of HSV-1-induced corneal scarring. METHODS: BALB/c or C57BL/6 mice were vaccinated with gK, ocularly challenged with HSV-1 strain KOS or McKrae, and the relative amount of corneal scarring determined 28 days after challenge. The T cells, total serum, or purified immunoglobulin G (IgG) isolated from gK-vaccinated mice was transferred individually to naive mice, and the affects on corneal scarring after HSV-1 challenge were determined. RESULTS: The KOS challenge of gK-vaccinated BALB/c mice resulted in significant corneal scarring (P = 0.0003), despite the fact that KOS normally produces no corneal scarring. McKrae challenge of gK-vaccinated C57BL/6 mice resulted in significant corneal scarring (P < 0.0001), despite the fact that C57BL/6 mice are normally refractory to HSV-1-induced corneal scarring. Passive transfer of total anti-gK mouse sera or purified anti-gK mouse IgG, but not adoptive transfer of total anti-gK T-cells to naive mice, resulted in exacerbation of corneal scarring after HSV-1 challenge (P < 0.0001). Mice defective for T-cell-dependent antibody production were not susceptible to exacerbation of HSV-1-induced corneal scarring by gK vaccination (P < 0.0001). CONCLUSIONS: The ability of gK vaccination to exacerbate HSV-1-induced corneal scarring was not mouse strain or HSV-1 strain specific. The gK-induced exacerbation of corneal scarring was related to anti-gK IgG. How anti-gK IgG exacerbated HSV-1 induced corneal scarring remains to be determined.

Animals↗