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Biomedical subjects

S Sun

Publications and source records attributed to S Sun.

At least 145 records · Page 8Linked to original sources
PubMed1999

Effects of hyper- and hypoventilation on gastric and sublingual PCO(2).

We investigated the effects of hyper- and hypoventilation on gastric (Pg(CO(2))) and sublingual (Psl(CO(2))) tissue PCO(2) before, during, and after reversal of hemorrhagic shock. Pg(CO(2)) was measured with ion-sensitive field-effect transistor sensor and Psl(CO(2)) with a CO(2) microelectrode. Under physiological conditions and during hemorrhagic shock, decreases in arterial (Pa(CO(2))) and end-tidal (PET(CO(2))) PCO(2) induced by hyperventilation produced corresponding decreases in Pg(CO(2)) and Psl(CO(2)). Hypoventilation produced corresponding increases in Pa(CO(2)), PET(CO(2)), Pg(CO(2)), and Psl(CO(2)). Accordingly, acute decreases and increases in Pa(CO(2)) and PET(CO(2)) produced statistically similar decreases and increases in Pg(CO(2)) and Psl(CO(2)). No significant changes in the tissue PCO(2)-Pa(CO(2)) gradients were observed during hemorrhagic shock in the absence or in the presence of hyper- or hypoventilation. Acute changes in Pg(CO(2)) and Psl(CO(2)) should, therefore, be interpreted in relationship with concurrent changes in Pa(CO(2)) and/or PET(CO(2)).

Animals↗
PubMed1999

Combined effects of buffer and adrenergic agents on postresuscitation myocardial function.

Although buffer agents alone have failed to improve the success of resuscitation, we now examine the widely held concept that it is the combined effect of alkaline buffer and adrenergic agents that improves outcomes of cardiopulmonary resuscitation. In the present report, the effects of both CO(2)-consuming and CO(2)-generating buffer agents in combination with adrenergic vasopressor drugs were investigated. Ventricular fibrillation was electrically induced in Sprague-Dawley rats weighing between 450 and 550 g. Precordial compression and mechanical ventilation were initiated after 8 min of untreated ventricular fibrillation. Animals were then randomized to receive bolus injections of either inorganic sodium bicarbonate buffer, organic tromethamine buffer, or saline placebo. The beta(1) adrenergic effects of epinephrine were blocked with esmolol. The vasopressor amine was injected 2 min after injection of the buffer agent. Electrical defibrillation was attempted at the end of 8 min of precordial compression. In 15 additional animals, the sequence of administration of the adrenergic vasopressor and buffer agents was reversed such that the adrenergic vasopressor was injected before the buffer agents. All animals were restored to spontaneous circulation. Both bicarbonate and tromethamine significantly decreased coronary perfusion pressure from 26 to 15 mm Hg and reduced the magnitude of the vasopressor effect of the adrenergic vasopressor. When the vasopressor preceded the buffer, declines in coronary perfusion pressure after administration of buffer agents were prevented. In each instance, however, greater impairment of postresuscitation myocardial function and decreased postresuscitation survival were observed after treatment with buffer agents.

Adrenergic beta-Agonists↗
PubMed1999

[Effect of hypertonic saline/dextran 70 on delayed resuscitation of dogs with burn shock].

OBJECTIVE: To investigate the effect of hypertonic saline/dextran 70 on delayed resuscitation of burn shock. METHODS: Eighteen mongrel dogs with 35% TBSA, third-degree burn were used in this study. Lactated Ringer's (LR) or 7.5% NaCl+ 6% dextran 70 (HSD) was given for resuscitation 6 h postburn. The volumes and rates of fluid infusion were controlled basically on the urinary output of 1.0 ml.kg-1.h-1 and cardiac output (CO) of 70%-80% of preburn values. The volume load, +dp/dtmax, -dp/dtmax, CI,DO2 and VO2 were obtained to evaluate the effect of HSD resuscitation. RESULTS: The resuscitated volume of HSD was 30.56% less during first 24 h postburn and 59.50% less at 4 h after resuscitation than LR's. The +dp/dtmax, CI,DO2 and VO2 were increased significantly with HSD infusion at 2 h, 1 h and 0.5 h after resuscitation compared with LR's. CONCLUSION: HSD could expand plasma volume significantly with small quantity. The cardiac contractility was enhanced and the oxygen delivery, oxygen consumption were increased in delayed resuscitation of burn shock.

Animals↗
PubMed1999

Early intervention promotes intellectual development of premature infants: a preliminary report. Early Intervention of Premature Infants Cooperative Research Group.

OBJECTIVE: To evaluate the effect of early intervention on the intellectual development of the premature infants. METHODS: Premature infants at gestational age of 28-36.9 weeks were randomly divided into two groups: intervention and conventional care groups. Normal newborn infants during the same period were included in the control group (routine care). Up to March 1996, 156 cases were over the age 1.5-2 years (corrected age), 52 in the intervention group, 51 in the conventional care group and 53 in the normal control group. Parents were taught to carry out the 0-2 year intervention program, which included motor, cognitive, speech development and social behavior. Every three months, height, weight and head circumference were measured. At the age of one and a half and two years, all infants in the three groups received infant development tests of Child Development Center of China (CDCC) scale. The examiner did not know which infant had received intervention. RESULTS: There was no significant difference in biological factors among the two premature groups and in cultural and social factors among the three groups. Intelligence tests at the age of one and a half and two years showed that the average mental development index (MDI) in the intervention group was 13.8 and 14.6 higher than those in the conventional care group and the differences were significant. The psychomotor development index (PDI) was 5.2 and 4.7 higher but the differences were not significant. The MDI and PDI in the intervention group and normal control were quite close, but at two years, the MDI and PDI in the intervention group were 5.7 and 7.3 higher than those in the normal control and the differences were significant (P < 0.05). Compared with the normal control, the MDI in conventional care group at one and a half and two years of age were 11.5 and 8.9 lower. The difference was very significant. There were four cases of mental retardation, whose mental development index (MDI) was less then 70 in the conventional care group, but none in the intervention group. CONCLUSIONS: Early intervention can promote intellectual development of the premature infants and may be beneficial to the prevention of mental retardation. Early and intensive intervention can produce better results. Bringing parent's initiative into full play through deepening their understanding of the importance of early intervention is the key to success.

Child Development↗
PubMed1999

[In situ observation of apoptosis and proliferation in breast cancer and its precancerous lesions].

OBJECTIVE: To investigate the effects of apoptosis and proliferation on malignant transformation of breast precancerous lesions by in situ observation. METHODS: The density and distribution of apoptotic cells were examined in 31 cases with breast cancer, 20 with dysplasia and 20 with hyperplasia, using TUNEL (TdT-mediated dUTP nick end labeling) technique and immunohistochemical method respectively. Eight normal breast tissues were used as the control. RESULTS: In normal breast tissue, apoptotic cells were located at the lacteals and gland follicles, facing the cavity. The proliferating cells were located at the basal layer of mucosa. These characteristics of distribution were lost in breast cancer and precancerous lesions. The density of apoptotic cells and proliferating cells of dysplasia was significantly higher than that in breast cancer and normal mucosa, The density of apoptotic cells and proliferating cells in breast cancer was significantly higher than that in normal mucosa. The ratio of apoptotic to proliferating cells in hyperplasia and dysplasia was 1:1.3-1.4, 1:1.1-1.2 respectively, and 1:2.3-2.4 in breast cancer. CONCLUSION: Abnormality in cell apoptosis and proliferation may play important role in the genesis of breast cancer.

Adult↗
PubMed1999

[The extraction of DNA from milligram amounts of wild mountain ginseng tissues].

OBJECTIVE: To keep wild mountain ginseng, a rare medicinal remedy, as intact as possible when extracting DNA from it, a new way to extract DNA has been explored. METHOD: The CTAB method was improved and a simple and direct way was developed. RESULT: From 0.001 g of dried samples of ginseng root DNA was obtained in an amount up to 2.25 micrograms. CONCLUSION: The RAPD fingerprinting generated by this DNA is as good as that by CTAB method. This new method may also be used for extraction of other precious Chinese medicinal materials.

DNA, Plant↗
PubMed1999

[Fusion expression of porcine IFN-gamma and Cysticercus cellulosae antigen cC1 in Escherichia coli cells].

AIM: To construct an expression vector, including a chimeric cDNA of porcine IFN-gamma and Cysticercus cellulosae antigen cC1. METHODS: DNA fragments of porcine IFN-gamma and cC1 including linkers were generated by polymerase chain reaction (PCR). The recombinant vector pJLA-PRcC1 was constructed by inserting a chimeric cDNA of porcine IFN-gamma and Cysticercus cellulosae antigen cC1, and transformed to E. coli XL-Blue. RESULTS: The recombinant vector was identified by restriction analysis. An inserted fragment about 1.5 kb could be found. After induction, a 52 kDa new protein band appeared in SDS-PAGE. CONCLUSION: The fusion expression of porcine IFN-gamma and cC1 antigen in Escherichia coli cells is successful.

Animals↗
PubMed1999

[Construction of DNA vaccine including a chimeric gene encoding Cysticercus cellulosae antigen and porcine interleukin-4].

AIM: To construct a fusion expression vector for DNA vaccine including porcine interleukin-4(IL-4) and antigen cC1 to enhance the protective immunity of Cysticercus cellulosae antigen cC1. METHODS: The cDNA fragments encoding porcine IL-4 and cC1 were amplified respectively by PCR and the fused. The obtained chimeric gene IL-4cC1 contained a synthetic linker of ten amino acids and the sequence surrounding its 5' AUG initiatory codon was changed to optimized translational initiation. RESULTS: Identified by restriction enzyme analysis, an insert fragment of 1.5 kb was demonstrated. It had the same sequence as reported and designed by DNA sequencing analysis. CONCLUSION: A fusion expression plasmid containing porcine IL-4 and cC1 was constructed.

Animals↗
PubMed1999

[Direct determination of raw plant drugs by FTIR].

Twenty-five common raw plant drugs were determined quickly and directly with diffuse reflectance drawing sample of FTIR for the first time. The results show that the drugs with different chemical compounds are characteristics of different peaks. The category of plant drugs may be firmly identified through their respective IR characteristic absorption spectrum. Furthermore, the approach can be achieved quickly and accurately without extraction and separation of samples.

Drugs, Chinese Herbal↗
PubMed1999

[Analysis of blue ballpoint ink components by FT-IR microspectrometry].

Systematical analysis on the 108 kinds of blue ballpoint writing inks with FT-IR microspectrometry is presented in this paper. The results show that the differences of the ink compounds keep some regular. These blue ballpoint writing inks can be classified by the transmittance spectra. The method is rapid, accurate, highly sensitive and nondestructive.

English Abstract↗
PubMed1998

Type I interferon-mediated stimulation of T cells by CpG DNA.

Immunostimulatory DNA and oligodeoxynucleotides containing unmethylated CpG motifs (CpG DNA) are strongly stimulatory for B cells and antigen-presenting cells (APCs). We report here that, as manifested by CD69 and B7-2 upregulation, CpG DNA also induces partial activation of T cells, including naive-phenotype T cells, both in vivo and in vitro. Under in vitro conditions, CpG DNA caused activation of T cells in spleen cell suspensions but failed to stimulate highly purified T cells unless these cells were supplemented with APCs. Three lines of evidence suggested that APC-dependent stimulation of T cells by CpG DNA was mediated by type I interferons (IFN-I). First, T cell activation by CpG DNA was undetectable in IFN-IR-/- mice. Second, in contrast to normal T cells, the failure of purified IFN-IR-/- T cells to respond to CpG DNA could not be overcome by adding normal IFN-IR+ APCs. Third, IFN-I (but not IFN-gamma) caused the same pattern of partial T cell activation as CpG DNA. Significantly, T cell activation by IFN-I was APC independent. Thus, CpG DNA appeared to stimulate T cells by inducing APCs to synthesize IFN-I, which then acted directly on T cells via IFN-IR. Functional studies suggested that activation of T cells by IFN-I was inhibitory. Thus, exposing normal (but not IFN-IR-/-) T cells to CpG DNA in vivo led to reduced T proliferative responses after TCR ligation in vitro.

Animals↗
PubMed1998

Reciprocal stimulation between TNF-alpha and nitric oxide may exacerbate CNS inflammation in experimental autoimmune encephalomyelitis.

Nitric oxide (NO) and TNF-alpha are both highly active pleotypic modulators of cell function that are abundantly generated during inflammation. Experiments in animal systems have linked the generation of NO and TNF-alpha to autoimmune pathogenesis, and blockade of either NO or TNF-alpha has been shown to impede disease development. In this study, we show that NO and TNF-alpha can act mutually to stimulate each other's production. While IFN-gamma alone induces NO release from microglia, astrocytes are provoked into significant NO production only by a combination of IFN-gamma and TNF-alpha. Since both TNF-alpha and NO are abundantly generated during T-glial cell interaction, we asked whether and how NO affects TNF-alpha production. Using an in vitro system in which TNF-alpha secretion is induced in MBP-reactive T cells by co-culture with syngeneic astrocytes, we observed that the efficiency of TNF-alpha secretion was markedly increased, in a dose-dependent fashion, by addition of micromolar concentrations of a chemical generator of NO donor, sodium nitroprusside (SNP). Similarly, low concentrations of SNP significantly enhanced the IL-2 dependent growth of MBP-reactive T cells. These results suggest that autoimmune pathogenesis initiated by inflammatory responses within the CNS may result in part from a vicious cycle in which TNF-alpha and NO mutually provoke each other's production.

Animals↗
PubMed1998

Transition-state theoretical interpretation of the catalytic power of pyruvate decarboxylases: the roles of static and dynamical considerations.

The catalytic power of two thiamin diphosphate (ThDP)-dependent enzymes, yeast pyruvate decarboxylase (the hysteretically regulated enzyme from Saccharomyces cerevisiae, SCPDC) and bacterial pyruvate decarboxylase (the unregulated enzyme from Zymomonas mobilis, ZMPDC), are analyzed by thorough-going application of transition-state theory, i.e. by a static approach that emphasizes the state-function character of the free energy of activation and takes no explicit account of dynamical considerations. The overall catalytic reaction is resolved into manifolds for addition (conversion of free enzyme and substrate to the complex of enzyme with the pyruvate:ThDP adduct), decarboxylation, and elimination (conversion of the complex of enzyme with the acetaldehyde:ThDP adduct formed by decarboxylation into free product and free enzyme). For SCPDC, the addition manifold is most strongly catalyzed (3x1012-fold, corresponding to net transition-state stabilization of 72 kJ/mol, transition-state stabilization of 83 kJ/mol diminished by reactant-state stabilization of 11 kJ/mol), the decarboxylation manifold is least strongly catalyzed (5x107-fold, corresponding to net transition-state stabilization of 41 kJ/mol, transition-state stabilization of 68 kJ/mol diminished by reactant-state stabilization of 27 kJ/mol), and the elimination manifold is catalyzed to an intermediate degree (2x1010-fold, corresponding to net transition-state stabilization of 59 kJ/mol, transition-state stabilization of 76 kJ/mol diminished by reactant-state stabilization of 17 kJ/mol). A similar situation holds for ZMPDC. There is no need to make an explicit analysis of dynamical factors in order to describe the catalytic mechanism and catalytic power of these complex enzymes.

Bacteria↗
PubMed1998

Cell death mediated by Fas-FasL interaction between glial cells and MBP-reactive T cells.

Apoptosis in T cells that have penetrated into the central nervous system (CNS) may be important for the physiological control of T cells with potentially dangerous reactivities to CNS antigens; such control may be dysfunctional in animals suffering from experimental autoimmune encephalomyelitis (EAE). In this study we examined the expression of Fas and FasL genes both in myelin basic protein (MBP)-reactive T cells and in glial cells and the susceptibility of these cells to death induced by Fas/FasL interaction. Both Fas and FasL gene expression is detectable in glial cells and MBP-reactive T cells. Cell death is not unidirectional: when T cells interact with glial cells death can be induced in the former or in the latter population. The ability to induce death of Fas-expressing cells varies greatly among different lines of MBP-reactive T cells, as does resistance to death induction by cells expressing FasL. Moreover, the ability of T cells both to deliver and to resist death signals is a function of their activation status: T cells freshly activated transmit a stronger apoptotic signal to Fas-positive target cells and are also more resistant to FasL-induced suicide. Soluble form of FasL provides a convenient titratable means of delivering death signals via Fas. However, comparison of the susceptibility of different targets to soluble FasL and to FasL expressed on the surface of a transfected glial line revealed differences, suggesting that signals arising from Fas/FasL interaction may be modulated by additional cell-surface molecules.

Animals↗
PubMed1998

DNA as an adjuvant: capacity of insect DNA and synthetic oligodeoxynucleotides to augment T cell responses to specific antigen.

How strong adjuvants such as complete Freund's adjuvant (CFA) promote T cell priming to protein antigens in vivo is still unclear. Since the unmethylated CpG motifs in DNA of bacteria and other nonvertebrates are stimulatory for B cells and antigen-presenting cells, the strong adjuvanticity of CFA could be attributed, at least in part, to the presence of dead bacteria, i.e., a source of stimulatory DNA. In support of this possibility, evidence is presented that insect DNA in mineral oil has even stronger adjuvant activity than CFA by a number of parameters. Synthetic oligodeoxynucleotides (ODNs) containing unmethylated CpG motifs mimic the effects of insect DNA and, even in soluble form, ODNs markedly potentiate clonal expansion of T cell receptor transgenic T cells responding to specific peptide.

Adjuvants, Immunologic↗