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S Sun

Publications and source records attributed to S Sun.

At least 199 records · Page 11Linked to original sources
PubMed1997

Phased chest and abdominal compression-decompression. A new option for cardiopulmonary resuscitation.

BACKGROUND: We describe a new manual method of phased chest and abdominal compression-decompression with a Lifestick resuscitator for cardiopulmonary resuscitation (CPR). METHODS AND RESULTS: Ventricular fibrillation (VF) was induced in 20 domestic pigs. After either 5 or 7 minutes of untreated VF, either phased chest and abdominal compression-decompression (Lifestick resuscitator) or precordial compression was initiated. Defibrillation was attempted at 2 minutes after the start of CPR. For the animals in which VF was untreated for 7 minutes, epinephrine was administered in doses of 20 micrograms/kg at 2 minutes after start of CPR. The coronary perfusion pressure generated by the Lifestick resuscitator was more than twofold greater (P < .01) than that generated by conventional precordial compression. Of 5 control animals, none were resuscitated after 5 minutes of VF. However, each of 5 animals treated with the Lifestick resuscitator was resuscitated (P < .01) and survived after 48 hours (P < .01). When untreated VF was prolonged to 7 minutes and epinephrine was administered, only 2 of the 5 control animals were resuscitated, and none of them survived for more than 4 hours. However, each of the Lifestick-treated animals was resuscitated and survived for more than 48 hours (P < .01). CONCLUSIONS: Phased chest and abdominal compression-decompression substantially increased hemodynamic efficacy of CPR and outcome in terms of successful resuscitation, 48-hour survival, and cerebral recovery.

Abdomen↗
PubMed1997

Tetrandrine inhibits signal-induced NF-kappa B activation in rat alveolar macrophages.

Tetrandrine is a bisbenzylisoquinoline alkaloid isolated from a natural Chinese herbal medicine. While this alkaloid has been shown to exhibit antifibrotic and anti-inflammatory activities, its mechanism of action is unknown. The present study was designed to investigate the inhibitory effect of tetrandrine on NF-kappa B activation in the alveolar macrophage. Three different provocative stimuli were used to activate NF-kappa B in these cells. The results indicate that tetrandrine can inhibit the activation of NF-kappa B and NF-kappa B-dependent reporter gene expression by LPS, PMA, and silica in a dose-dependent manner. In contrast, at the doses used, tetrandrine did not interfere with Sp-1 DNA binding activity or Sp-1-dependent reporter gene expression in these cells. Western blot analysis suggests that the inhibitory effect of tetrandrine on NF-kappa B activation can be attributed to its ability to suppress signal-induced degradation of I kappa B alpha, a cytoplasmic inhibitor of the NF-kappa B transcription factor.

Alkaloids↗
PubMed1997

A strategy for electron tomographic data collection and crystallographic reconstruction of biological bundles.

Structures of highly ordered biological bundles have unique features which call for special experimental and computational methods in electron cryomicroscopy. They can be considered as three-dimensional quasi-crystals and reconstructed using a crystallographic approach. However, they are neither "infinitely" large with respect to the borders of the bundle, nor are they a single unit cell in thickness along the viewing direction. Also, because of their shape, bundles do not generally have a preferred azimuthal orientation, which poses challenges for orientation estimation and refinement. We developed a strategy for recording and processing electron cryomicroscopic images that differs from classical two-dimensional crystalline reconstruction techniques. These developments allowed us to merge data from tomographic tilt series of ice-embedded acrosomal bundles. The goal is to determine accurately amplitudes and phases at the diffraction maxima in terms of hkl indices, and compute a three-dimensional map from the diffraction data.

Acrosome↗
PubMed1997

Nifedipine protects small intestine from cyclosporine-induced hemodynamic and functional impairment.

We have previously shown that cyclosporine (CsA) causes intestinal hemodynamic and functional impairments. In this study, we evaluated whether nifedipine protects the small intestine from such toxic side effects. Isogeneic small intestinal transplantation was performed in rats which then received one of the following two-week treatments: olive oil, 0.15 ml/kg/day i.m. as vehicle controls in group 1; nifedipine, 1 mg/kg/day i.m. in group 2; CsA, 15 mg/kg/day i.m. in group 3; and both nifedipine and CsA in group 4. Vascular resistance, whole tissue blood flow and its mucosal and serosal/muscularis distributions in both graft and recipient residual native intestines, and absorptive function were determined. The data showed that two-week treatment with CsA resulted in a marked elevation of vascular resistance from 51.0 +/- 6.8 to 72.4 +/- 11.1 U/g in the native whole tissue and from 53.7 +/- 7.2 to 78.2 +/- 12.1 U/g in the graft whole tissue, and decreases in blood flow from 1.59 +/- 0.26 to 1.11 +/- 0.17 ml/g/min in the native whole tissue and from 1.50 +/- 0.21 to 1.03 +/- 0.18 ml/g/min in the graft whole tissue and absorption from 227 +/- 36 to 166 +/- 26 mg glucose/dl. Mucosa was preferentially affected, while serosal/muscularis layers remained relatively unchanged. When nifedipine was concomitantly used with CsA, vascular resistance and blood flow values in the mucosal layer and whole intestinal tissue as well as absorptive function showed no significant differences from the baseline data. The changes observed in denervated grafts and recipient native intestines were similar. We conclude that nifedipine is effective in protecting both graft and native small intestines from CsA-induced toxicity in the rat.

Animals↗
PubMed1997

Neonatal effects and serum cortisol levels after multiple courses of maternal corticosteroids.

OBJECTIVE: To determine the effects of multiple courses of maternal betamethasone for fetal lung maturation on neonatal serum cortisol levels and clinical Cushing syndrome. METHODS: Seventy-nine mother-infant pairs delivered between 24 and 36 weeks' gestation were enrolled in the study. They were grouped according to the number of courses of betamethasone received between 24 and 34 weeks' gestation for fetal lung maturation: those receiving no courses, one course, and two or more courses. Physical examinations were performed and serum glucose, electrolyte, and cortisol levels were measured on days 1 and 3 of life. RESULTS: For those receiving multiple courses of betamethasone (n = 43), the mean (+/- standard error of the mean [SEM]) number of courses was 5.3 +/- 0.4, with a mean (+/-SEM) total dose of 125.0 +/- 10.7 mg. No neonates had findings suggestive of Cushing syndrome. Day 1 cortisol levels (pooled mean +/- SEM) were 12.6 +/- 2.4, 5.3 +/- 3.2, and 4.4 +/- 1.8 microg/dL in those receiving no courses, one course, and two or more courses, respectively (P = .03; no courses versus two or more courses, P = .03), but the differences were not significant when corrected for multiple variables. Differences among day 3 cortisol levels (pooled mean +/- SEM) were not significant: 8.3 +/- 1.6, 5.8 +/- 1.4, and 5.8 +/- 0.9 microg/dL in those receiving no courses, one course, and two or more courses, respectively. None of the neonates in the group receiving no courses of betamethasone had day 1 cortisol levels lower than normal, whereas 22% and 11% of the neonates receiving one and two or more courses, respectively, had day 1 levels lower than normal. On day 3, 15% of those receiving one course and 10% of those receiving two or more courses had serum cortisol levels lower than normal, whereas none of those who received no courses had a low cortisol level. Multivariate regression analysis could show no association between the number of courses or total dose of betamethasone and the day 1 or day 3 cortisol values. The day 1 cortisol level (log10) was most associated with the severity of respiratory distress syndrome (RDS) and day 3 cortisol level (log10) with race and severity of RDS. Only in neonates with absent or mild RDS did number of courses correlate with day 3 cortisol levels (log10), but this was a positive correlation. CONCLUSION: Serum cortisol levels either were independent of the number of courses or total dose of corticosteroids given or, in a subpopulation, were associated with increasing levels with increasing doses, suggesting that there is no suppressive effect with repeated dosing.

Betamethasone↗
PubMed1997

Cell density and antioxidant vitamins determine the effects of hyperoxia on proliferation and death of MDCK epithelial cells.

Epithelial cells are prone to oxidant injury, which could change epithelial cell homeostasis and lead to degenerative diseases. We examined the effects of hyperoxia on death and proliferation off Madin-Darby canine kidney (MDCK) epithelial cells and antioxidant vitamin protection. Subconfluent and near-confluent MDCK cells were cultured under normoxia or hyperoxia for two days. We measured cell number and viability, mitochondria enzymatic activity, thymidine incorporation, necrosis [lactate dehydrogenase (LDH) release], and apoptosis (DNA fragmentation and morphological changes). When the cells were subconfluent, hyperoxia decreased the number of adherent cells, mitochondrial enzymatic activity, and thymidine incorporation, but neither LDH release nor apoptotic changes increased compared with normoxic controls. In normoxia, near-confluent cells had lower nonadherent cell numbers, mitochondrial enzymatic activity, and thymidine incorporation than subconfluent cells; hyperoxia further decreased the latter two parameters and increased apoptotic changes and LDH release in near-confluent cells. Vitamin E protected mitochondrial enzymatic activity, apoptotic changes, and LDH release against hyperoxic injury but did not affect changes in thymidine incorporation with hyperoxia. Vitamin C partially protected the mitochondrial enzymatic activity and thymidine incorporation in subconfluence, but not in near confluence. These results indicate that cell density is a major determinant of the effects of hyperoxic injury and the profile of antioxidant vitamin protection.

Animals↗
PubMed1997

Familial nontoxic multinodular thyroid goiter locus maps to chromosome 14q but does not account for familial nonmedullary thyroid cancer.

Thyroid goiter is a common condition that is often associated with iodine deficiency. Familial forms of goiter in areas not known to feature iodine deficiency are much less common. We have performed a genomic search on a single large Canadian family with 18 cases of nontoxic multinodular goiter in which 2 individuals also had papillary lesions highly suggestive of papillary carcinoma. A locus on chromosome 14q (MNG1 [multinodular goiter 1]) has been identified, with a maximal two-point LOD score of 3.8 at D14S1030 and a multipoint LOD score of 4.88 at the same marker, defined by D14S1062 (upper boundary) and D14S267 (lower boundary). The gene encoding thyroid-stimulating hormone receptor (TSHR), which is located on chromosome 14q, is outside the linked region. To determine the role of this gene in familial nonmedullary thyroid cancer (NMTC), we studied 37 smaller pedigrees each containing at least two cases of NMTC. Analysis by both parametric and nonparametric methods indicates that only a very small proportion of familial NMTC (point estimate 0.001, support intervals 0-.6 under a dominant model) is attributable to MNG1.

Canada↗
PubMed1997

Modification of Cys-837 identifies an actin-binding site in the beta-propeller protein scruin.

In the acrosomal process of Limulus sperm, the beta-propeller protein scruin cross-links actin into a crystalline bundle. To confirm that scruin has the topology of a beta-propeller protein and to understand how scruin binds actin, we compared the solvent accessibility of cysteine residues in scruin and the acrosomal process by chemical modification with (1,5-IAEDANS). In soluble scruin, the two most reactive cysteines of soluble scruin are C837 and C900, whereas C146, C333, and C683 are moderately reactive. This pattern of reactivity is consistent with the topology of a typical beta-propeller protein; all of the reactive cysteines map to putative loops and turns whereas the unreactive cysteines lie within the predicted interior of the protein. The chemical reactivities of cysteine in the acrosomal process implicate C837 at an actin-binding site. In contrast to soluble scruin, in the acrosomal process, C837 is completely unreactive while the other cysteines become less reactive. Binding studies of chemically modified scruin correlate the extent of modification at C837 with the extent of inhibition of actin binding. Furthermore, peptides corresponding to residues flanking C837 bind actin and narrow a possible actin-binding region to a KQK sequence. On the basis of these studies, our results suggest that an actin-binding site lies in the C-terminal domain of scruin and involves a putative loop defined by C837.

Actins↗
PubMed1997

The actions of polynucleotides on effector stage cloned murine T-helper cells differ in each subset and depend on antigen concentration.

Polynucleotides enhance T-helper (Th) cell-mediated humoral immune responses in naive resting Th cells, B cells, and antigen-presenting cells (APC) from unprimed mouse spleen. If polynucleotides augment Th cell functions independent of the activation stage of Th cells, then polynucleotides may cause hyperimmune responses. In this study we examined the effects of polynucleotides on effector-stage murine Th cell clones in vitro. The A.E7 clone (primed with pigeon cytochrome C, origin: B10.A mice) and CDC35 clone (primed with rabbit gamma-globulin, origin: DBA/2 mice) were used as representative type 1 (Th1) and type 2 (Th2) Th cells, respectively. Th clones were stimulated with antigen (Ag) in polynucleotide-supplemented or control cultures in the presence of syngeneic spleen cells (either CD4- or irradiated). The number of antibody (Ab)-secreting cells was counted to measure T-dependent Ab production. Production of interferon-gamma (IFNgamma) for the Th1 clone and interleukin-5 (IL-5) for the Th2 clone were measured. Without Ag stimulation, cytokine production and the number of Ab-secreting cells formed were very low and not altered by polynucleotides. With suboptimal Ag challenges provided by Ag-primed spleen cells, polynucleotides enhanced IFNgamma production by the Th1 clone, while they suppressed Th1 clone-mediated Ab production and IL-5 production by the Th2 clone. Polynucleotides did not alter Th2 clone-mediated Ab production. These actions of polynucleotides appeared to be dose-dependent. With optimal Ag challenges, polynucleotides did not affect our measures of Th cell activation. Polynucleotide action in vitro on effector-stage Th cell clones differed in each Th cell subset and depended on Ag concentration.

Animals↗
PubMed1997

Adverse effects of interrupting precordial compression during cardiopulmonary resuscitation.

OBJECTIVES: In the current operation of automated external defibrillators, substantial time may be consumed for a "hands off" interval during which precordial compression is discontinued to allow for automated rhythm analyses before delivery of the electric countershock. The effects of such a pause on the outcomes of cardiopulmonary resuscitation were investigated. DESIGN: Prospective, randomized, controlled animal study. SETTING: Research laboratory. SUBJECTS: Male Sprague-Dawley rats. INTERVENTIONS: Ventricular fibrillation was electrically induced in 25 Sprague-Dawley rats. After 4 mins of untreated ventricular fibrillation, precordial compression was begun and continued for 6 mins. Animals were then randomized to receive an immediate defibrillation shock or the defibrillation attempt was delayed for intervals of 10, 20, 30, or 40 secs. MEASUREMENTS AND MAIN RESULTS: Immediate defibrillation restored spontaneous circulation in each instance. When defibrillation was delayed for 10 or 20 secs, spontaneous circulation was restored in three of five animals in each group. After a 30-sec delay, spontaneous circulation was restored in only one of five animals (p < .05). No animal was successfully resuscitated after a 40-sec delay (p < .01). With increasing delays, 24- and 48-hr survival rates were correspondingly reduced. CONCLUSIONS: During resuscitation from ventricular fibrillation, prolongation of the interval between discontinuation of precordial compression and delivery of the first electric countershock substantially compromises the success of cardiac resuscitation. Accordingly, automated defibrillators are likely to be maximally effective if they are programmed to secure minimal "hands off" delay before delivery of the electric countershock.

Animals↗
PubMed1997

Factors controlling the turnover of T memory cells.

Most of the T cells participating in the primary immune response are rapidly eliminated, but small numbers of these cells survive and differentiate into long-lived memory cells. Information on the life history of memory cells can be obtained by studying the component of memory-phenotype T cells found in normal animals; these cells are presumed to represent memory cells specific for various environmental antigens. For CD8+ cells, in vivo exposure to viruses and certain other infectious agents causes a large proportion of memory-phenotype (CD44hi) cells to enter the cell cycle. In this situation, stimulation of CD44hi CD8+ cells does not seem to require T-cell receptor ligation and appears to reflect release of various cytokines, especially type I interferon. The capacity of infectious agents to induce non-antigen-specific stimulation of T cells may play a role in boosting the survival of memory cells and perhaps also in providing an adjuvant function during the primary response.

Animals↗
PubMed1997

Microbiologic and clinical value of primary broth cultures of wound specimens collected with swabs.

In order to assess the microbiologic and clinical value of primary broth culture of wound specimens collected with swabs and submitted to the laboratory in transport medium, we compared the results of primary agar culture with the results of a corresponding primary broth culture for 344 aerobic specimens and 176 anaerobic specimens. While 8.7% (45 of 520) of the specimens yielded organisms from the primary broth culture that were not recovered from the corresponding primary agar culture, only 5.0% (26 of 520) of the specimens yielded organisms from the primary broth culture other than Staphylococcus epidermidis, viridans group streptococci, and Corynebacterium spp. Moreover, the primary broth culture of only 0.6% (3 of 520) of the specimens yielded organisms not recovered from the primary agar culture that caused a change in the therapy of the patient. Our conclusion is that primary broth cultures are unnecessary for the processing of wound specimens properly collected with swabs.

Bacteria, Aerobic↗
PubMed1997

Involvement of NF-kappaB in silica-induced cyclooxygenase II gene expression in rat alveolar macrophages.

The role of nuclear factor (NF)-kappaB transcription factor in silica-induced cyclooxygenase (COX) II gene expression was examined in the rat alveolar macrophage cell line NR8383. Our results indicate that NF-kappaB can be activated in this cell line by silica exposure. Suppression of NF-kappaB activation in these cells leads to an attenuation of COX II mRNA accumulation induced by silica. Using an electrophoretic mobility shift assay and a reporter gene assay, we provide evidence that at least two kappaB sites in the 5'-flanking region of the rat COX II gene are involved for silica-induced transcriptional control of the COX II gene. The first motif, -404 GGGGATTCCC -395, is absolutely conserved in sequence and is localized in a similar position among the COX II genes found in humans, rats, and mice. The second motif, -91 GGGGAAAGCC -82, was conserved only in the mouse and rat COX II genes in sequence and in location. Aspirin, a COX inhibitor, was shown to suppress silica-induced NF-kappaB activation. However, prostaglandin E2, one of the important downstream reaction products catalyzed by the COX enzyme, was also shown to attenuate silica-induced NF-kappaB activation by retarding the degradation of silica-induced inhibitor NF-kappaB. These results suggest that an interdependent regulation may exist between NF-kappaB activation and COX or its products.

Animals↗
PubMed1997

Esophageal PCO2 as a monitor of perfusion failure during hemorrhagic shock.

Measurement of gastric wall PCO2 (PgCO2) by tonometric method has emerged as an attractive option for estimating visceral perfusion during circulatory shock. However, gastric acid secretion obfuscates the tonometric measurement. We, therefore, investigated the option of measuring PCO2 in the esophagus to minimize these restraints. Hemorrhagic shock was induced in five Sprague-Dawley rats, and five rats served as sham controls. PgCO2 was measured with an ion-sensitive field effect transistor that was surgically implanted into the gastric wall. Esophageal luminal PCO2 (PeCO2) was measured by a second ion-sensitive field effect transistor sensor. During hemorrhagic shock, mean aortic pressure declined from 150 to 50 mmHg. Gastric blood flow decreased from 58 to 12 ml.min-1.100 g-1 (21% of preshock) and esophageal blood flow from 44 to 7 ml.min-1.100 g-1 (16% of preshock). PgCO2 simultaneously increased from 47 to 116 Torr and PeCO2 from 47 to 127 Torr. The increases in PgCO2 were highly correlated with increases in PeCO2 (r = 0.90). Esophageal tonometry may, therefore, serve as a practical alternative to gastric tonometry.

Animals↗
PubMed1997

Universal newborn hearing screenings: a three-year experience.

OBJECTIVE: To perform hearing screenings on all newborns before hospital discharge, using auditory brainstem evoked responses with analysis of time, cost, and failure rates to evaluate and determine the screening practicality. METHOD: Over a 3-year period from January 1, 1993 to December 31, 1995, auditory brainstem evoked response screenings were performed on 15 749 infants born at Saint Barnabas Medical Center, Livingston, New Jersey, before their hospital discharge by certified/licensed audiologists. The auditory brainstem evoked response screenings were conducted using the Nicolet Compass Evoked Potential System. RESULTS: A 3-year experience of testing 15 749 infants proved to be a cost-effective program with costs less than $30.00/baby. To date, 46 babies have been identified with bilateral sensorineural hearing loss and 6 babies with unilateral sensorineural hearing loss. CONCLUSIONS: The universal newborn hearing screening program at Saint Barnabas Medical Center has proved to be effective, beneficial, and necessary for an institution with more than 5000 births, annually. Early identification of hearing loss has resulted in infants receiving early intervention, and the screening program has provided education and follow-up services to both parents and physicians.

Audiometry↗
PubMed1997

[Finite element analysis of force produced by "T" loop retraction archwire].

This study introduced three presumed springs to imitate the three dimensional bolstering function of the bracket-tooth-periodontal tissue on the archwire with three dimensional finite element method (FEM), and, systematically analysed the force system produced by the "T" loop retraction archwire on the incisors. The following conclusions were drawn; (1) The activation of the "T" loop retraction archwire will produce extrusion and root lingual torque force as well as horizontal force on the incisors; (2) Adequate torqul on the incisor segment and gable bend mesial to the T-loop are necessary to control the position of the anterior teeth while they are being retracted; (3) retraction archwire should not be activated too much; (4) Lighter wire will produce milder and more durable forces.

Biomechanical Phenomena↗
PubMed1997

[Pharmacological study on magnetite].

Magnetite can markedly inhibit the rodent turn-around reaction induced by acetic acid, reduce the threshold dose of pentobarbital sodium and shorten rodent's incubation period of falling asleep. It has also the following effects; antagonizing metrazol which causes rodent convulsions, postponing the incubation period of being startled by Huisuling, cutting down the extent of rodent's foot swells caused by JCCJ, and diminishing bleeding time and congulating time.

Analgesics↗