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C Shen

Publications and source records attributed to C Shen.

At least 91 records · Page 5Linked to original sources
PubMed1996

[The angiographic classification and endovascular therapy of the vein of Galen aneurysmal malformation].

We treated 11 cases of the vein of Galen aneurysmal malformation, one of which was diagnosed by MRI only, and 10 underwent CAG diagnostic procedure. Among the 10 CAG diagnosed cases, 5 were classified as the vein of Galen aneurysmal malformation (VGAM) with the AV shunt directing to the vein of Galen. The other 5 were classified as the vein of Galen aneurysmal dilitation (VGAD) secondary to parenchymal AVM or dural AVF. 8 cases underwent endovascular treatment. For VGAM, the shunts in the wall of the vein were embolized. For VGAD, the primary AVM or AVF were embolized. The pathphysiology, angiographic characteristics, classification and the principle of endovascular therapy of the vein of Galen aneurysmal malformation were discussed.

Adolescent↗
PubMed1995

Synthesis and characterization of a homogeneous chemical conjugate between basic fibroblast growth factor and saporin.

Basic fibroblast growth factor (FGF-2) and saporin were chemically conjugated using the crosslinker, N-succinimidyl-3(2-pyridyldithio)-propionate. When purified, the conjugate was found to be heterogeneous as analyzed by SDS/PAGE, size-exclusion HPLC and reverse-phase HPLC. Therefore, we sought to synthesize a molecule that would be homogeneous and thus easier to characterize and evaluate its efficacy and toxicity for pharmaceutical drug development. A homogeneous chemical conjugate was successfully synthesized by using a mutant FGF-2 with Cys96 replaced by Ser ([S96]FGF-2) and a recombinant saporin mutant containing a single Cys at the -1 position (C-SAP). The latter was expressed in Escherichia coli and isolated to 99% purity by expanded-bed adsorption chromatography followed by cation-exchange chromatography. The cysteine in C-SAP was activated by Ellman's reagent and then reacted with the only available cysteine (position 78) in [S96]FGF-2 to produce the homogeneous conjugate, designated as FGF2-C-SAP. The purified FGF2-C-SAP was more than 98% pure as judged by HPLC. In vitro biological assays indicated that FGF2-C-SAP was a potent inhibitor of protein synthesis in a cell-free system and was cytotoxic to FGF-receptor-bearing cells.

Amino Acid Sequence↗
PubMed1995

Selection of a gene for apolipoprotein A1 using autoantibodies from a patient with systemic lupus erythematosus.

OBJECTIVE: To investigate immunoreactivity of systemic lupus erythematosus (SLE) sera with apolipoprotein A1, (Apo A1), the major lipid-binding protein of high-density lipoprotein (HDL). METHODS: Since early attempts to identify Apo A1 autoantibodies using standard enzyme-linked immunosorbent assay (ELISA) and immunoblotting techniques had been unsuccessful, a mouse complementary DNA lambda phage expression library was screened. RESULTS: A selected clone (MA1) was found to have 82% DNA sequence homology to a segment of human Apo A1. Since there were nonconservative substitutions in the MA1 protein and lack of a complete sequence, it was possible that the SLE patient's antibodies were binding MA1 epitopes that were shared by the complete human protein but had not been conformationally accessible using the earlier techniques. Thus, gamma-irradiated ELISA plates were used as an alternative antigen-binding surface for intact human Apo A1, and high-titer anti-human Apo A1 autoantibodies were then identified in the sera of 5 more SLE patients. CONCLUSION: These findings show that Apo A1 is immunogenic. Apo A1 antibodies may play a role in the decreased HDL levels and Apo A1:Apo B ratios previously reported to occur in subgroups of SLE patients.

Amino Acid Sequence↗
PubMed1995

Influence of autonomic blockade and aging on AV conduction and responses to verapamil in the beagle.

BACKGROUND: Age-related differences in responses to verapamil have been noted in both intact humans and isolated denervated perfused rat hearts. The study was designed to determine the effects of aging on intracardiac conduction and pharmacodynamic responses to verapamil, and also to determine the potential role of autonomic responses in previously reported age-related differences in responses to verapamil. METHODS: After stability of measures was demonstrated in senescent animals, nine young (aged 3-4 years: 12.3 +/- 2.4 kg; 5 female, four male) and nine senescent (aged 8-11 years: 12.0 +/- 2.2 kg; 5 female, four male) beagles were randomized to undergo 60-minute verapamil infusions during pentobarbital anesthesia alone or after 1 mg/kg propranolol and 0.5 mg/kg atropine. RESULTS: In the nonblocked state, verapamil increased A-A intervals (p < .001), P-R (p < .001), A-H intervals (p < .001), and AV Wenckebach block cycle length (p < .0001) and decreased blood pressure (p < .001) without age-related differences in responses. After autonomic blockade, heart rate and blood pressure decreased (p < .0001) and AV conduction intervals (p < .05) and AV Wenckebach block cycle length increased (p < .006). A-A intervals, A-H intervals, and AV Wenckebach block cycle length were significantly longer in senescent vs young beagles (559 +/- 87 vs 471 +/- 42 msec, p < .002; 103 +/- 6 vs 89 +/- 14, p < .05), 273 +/- 21 vs 238 +/- 26, p < .006, respectively). Verapamil effects on heart rate (p < .001) and AV conduction intervals (p < .007) and diastolic blood pressure (p < .003) were enhanced in younger, but not senescent, beagles after propranolol and atropine. DISCUSSION: Verapamil produced similar effects on heart rate, blood pressure, and AV conduction in young and senescent beagles during barbiturate anesthesia. After double pharmacologic autonomic blockade, heart rate and AV conduction intervals and AV Wenckebach cycle length were significantly longer in senescent beagles when compared to younger beagles. Responses to verapamil after pharmacologic double autonomic blockade were enhanced only in younger beagles, suggesting greater contribution of reflex responses to results during verapamil infusions in the nonblocked state in younger animals.

Aging↗
PubMed1994

Control of lymphocyte integrin function: evidence for multiple contributing factors.

The control of lymphocyte adhesion is critical for proper cellular functions. The alpha 2 beta 1 integrin complex serves as a receptor for collagen on lymphocytes. The T cell leukemia Jurkat expresses alpha 2 beta 1 in a latent form on the cell surface. Three types of stimuli, antibody to the alpha 2 chain (JBS2), antibody to the beta 1 chain (JB1B), and phorbol ester (PMA), each induce activation of alpha 2 beta 1-dependent Jurkat binding to collagen. A comparison of the JBS2, JB1B, and PMA induction requirements indicated that the JB1B and the JBS2 effects are not sensitive to staurosporine while the PMA response is completely inhibited. Combinations of functionally saturating concentrations of the stimuli displayed an additive effect. Collectively these results suggest that several factors contribute to the generation of full integrin functionality and cellular adhesion, thus providing a possible basis for incrementally controlling the adhesive potential of lymphoid cells.

Alkaloids↗
PubMed1994

Effect of hydration on the biaxial flexural strength of a glass ionomer cement.

OBJECTIVES: The purpose of this study was to test the hypothesis that hydration during setting enhances the strength of glass ionomer cements. METHODS: Thirty-four groups of eight disks each were prepared and sealed in nonpermeable bags to age for 30 min to 360 d before biaxial flexure testing. At each time interval, one group was tested immediately, while the second group was immersed in water for an additional 48 h prior to the same testing. Six of each group were used for strength testing and the remaining two were placed in a desiccator for determining evaporative water content with respect to initial weight. RESULTS: A major portion of the disk strength developed within the first 2 wk and continued to improve at a much slower pace with time. Tukey's multiple range test indicated that additional 48 h immersion caused significant strength reduction for disks aged less than 30 d. The amount of weight loss in the desiccator decreased with aging time. The profiles of biaxial flexure strengths with respect to weight loss are similar for both groups. It infers that additional water storage introduces surface flaws that result in the strength reduction. SIGNIFICANCE: Glass ionomer cement must be kept from direct water contact as long as possible to reach an acceptable level of strength.

Analysis of Variance↗
PubMed1994

Sensitivity of catalyst/base ratio on curing of resin luting agents: polymerization exotherm analysis.

OBJECTIVES: Currently, the proposed test of the International Standardization Organization (ISO) for measuring working and setting times of resin luting agents is based on measurement of times to reach specified stages on the polymerization exotherm. The objective of this study was to use this test to investigate the influence of variations in the mass ratios of catalyst paste to base paste on the working and setting times of three dual-cured dental resin luting agents. METHODS: The materials used were Dicor Light Activated Cement (Dentsply International Inc.), Palfique Inlay Resin Cement (Tokuyama Soda Co.), and Vivadent Dual Cement (Vivadent). Fifteen specimens of each material were tested for working time by spatulating mass ratios from 0.7 to 1.3 for 30s at 23 degrees C and recording the time from beginning of spatulation to the time at which a temperature increase occurs. Ten specimens of each material were tested for setting time by spatulating in a similar manner at 37 degrees C and recording the time at which the temperature reaches a maximum value. RESULTS: The data were fitted to the relation, In t = In A + Bm, where t is the time in seconds, m is the mass ratio, and A and B are regression coefficients. The results suggest that working and setting times of the specimens were independent of variations in mass ratio. A comparison among the materials was made by using a multiple linear regression with the relation, In t = In C + Dm + E gamma + Fm gamma, where gamma is a dummy variable to help distinguish between materials, and C, D, E, and F are regression coefficients. The results suggest that differences in materials influence the working time but not the setting time. SIGNIFICANCE: These results infer that variations in mass ratio (+/- 20%) often observed in the clinical setting should not have a significant influence on the working and setting times of resin luting agents.

Acrylic Resins↗
PubMed1994

The development of an instrument to measure self-consistency.

The maintenance of self-consistency is a task that engages elderly people, and it can be viewed as an indicator of how well a person can cope with stress in the ageing process. However, there is no reliable and valid instrument to date that measures this phenomenon. To help elderly people to accomplish the task warrants the necessity to develop an instrument to measure self-consistency. The purpose of this study was to develop an instrument to measure self-consistency in elderly people with chronic conditions. The Self-Consistency Scale (SCS) was designed and administered to hearing-impaired elderly people (n = 130) in the north-east part of the USA. Psychometric properties of the SCS were evaluated and the results indicated a promising psychometric integrity. The obtained alpha coefficient for the SCS total scale was 0.89, with a score range of 51-104 and a mean total score of 85.10 (SD = 11.04). Convergent validity of the SCS was established by correlating the SCS to a Visual Analogue Scale--A Sense of Self (VAS), r = 0.60 (P < 0.01). Divergent validity with the Geriatric Depression Scale (GDS) was established, r = -0.57 (P < 0.01). Maximum likelihood factor analysis with oblimin rotation resulted in a two-factor solution: Factor I, self-knowledge; and Factor II, stability of self-concept.

Adaptation, Psychological↗
PubMed1994

System for the pH-dependent release of a dye in model dental restorations.

We are developing a system for detecting recurrent caries under dental restorations. The controlled release of dyes under conditions of likely demineralization will alert the dentist to potential secondary caries. Production of acidic species is a characteristic of caries activity; hence, the system uses pH-sensitive polymers to release markers when the pH at the cavity wall of the restored tooth is below 6.5. The objectives of this investigation were to test the hypotheses that (1) the proposed system can be designed to release detectable marker continuously for at least six months in a simulated carious environment, and (2) the transient pH changes in the oral cavity caused by simulated dietary intake will not induce premature marker release from the pH-sensitive polymer placed beneath restorations. Two types of dye-loaded microspheres based on styrene, vinylpyridine, and divinylbenzene were prepared and placed on the floor of model cavity preparations made from an acrylic rod. Each model cavity was restored with a hybrid dental composite, placed in a vial with 5 mL of sodium-lactate/lactic-acid base buffer solution, and stored at 37 degrees C. Solutions of three different pH values were used: 2.86, 4.73, and 6.39. The dye release into storage media was monitored periodically with a UV/VIS spectrophotometer. Results showed that the duration could extend beyond six months for pH > 4.73, and that transient oral pH changes are not likely to result in premature dye release. The data indicate that it would take approximately 21 days for the acidic agent external to the restoration to initiate dye release from restored sites.

Coloring Agents↗
PubMed1994

Identification of pathogenic leptospires by recombinant DNA probes.

Early diagnosis of leptospirosis of pulmonary diffuse hemorrhage type (PDH) is of crucial importance in saving patients. To develop a sensitive and specific method for diagnosis, a genomic library of the main pathogen of PDH, L. interrogans serovar lai strain 017, was constructed with the plasmid vector pUC9. Recombinant plasmids which have homologous fragments of pathogenic leptospires were screened from the bank. A recombinant plasmid, designated pCX7, could detect 1.7 kb fragment of strain 017, 9.0 kb of strain 601 and 30.0 kb of strain Hebdomadis, respectively, without cross hybridization with nonpathogenic leptospires such as L. biflexa strain Patoc I and Leptonema illini. The recombinant plasmid pCX7 could detect pathogenic leptospires which are the main pathogens endemic to Sichuan Province.

Blotting, Southern↗
PubMed1994

[Specificity of the recombinant DNA pCX7 and its restriction enzyme map].

The recombinant DNA pCX7 derived from L. interrogans serovar lai strain 017 was applied for hybridization with 17 strains (8 serogroups of L. interrogans, L. biflexa strain Patoc I and Leptonema strain 3055); meanwhile 15 restriction endonucleases were used for analysis of the restriction enzyme map of pCX7. The result showed that the recombinant DNA probe is specific to species L. interrogans and its homology with DNA from different leptospires. A restriction enzyme map of pCX7 was constructed. Unique site for Bgl II and 3 sites for Bst BI were located within the cloned fragment (1.7 kb).

DNA, Bacterial↗
PubMed1994

[Characterization of leptospiral DNA by southern hybridization serovar lai recombinant probe pCX7].

The recombinant probe pCX7, derived from genomic library of serovar lai strain 017, was applied for the characterization of DNA from 20 strains of leptospires in different genus species, sero-groups and serovars by southern hybridization. The probe, specific to partial species L. interrogans, did not hybridized with DNA of L. biflexa strain Patoc I and L. illini strain 3055, neither with DNA of serovars javanica, manhao 2 and ranarum which had shown very weak virulence, but hybridized with DNA of the other 15 strains of L. interrogans in 8 serogroups. It was easy to distinguish the banding patterns, since the pCX7 probe hybridized with a limited number of DNA fragments. Different leptospires showed different banding patterns. A few differences between strain 017 (strain of strong virulence) and strain 601 (strain of weak virulence) of serovar Lai were observed although their hybridization banding patterns were very similar. Differences in hybridization signals in combination with the banding pattern appear to provide good characteristics for identification of leptospiral serogroups and serovars, even strains. The result indicated that southern hybridization with the probe pCX7 might provide good tools for identification of leptospira.

Blotting, Southern↗
PubMed1994

[Relative DNA content and cycle distribution of cells in pleural effusions studied by flow-cytometry].

Pleural effusions from 28 patients were studied by cytology, chromosome and flow-cytometry. Relative cellular DNA content was measured. An estimate of ploidy as well as cycle distribution has been given. Eighteen patients suffered from malignant effusions while the rest had TB effusions. 83.3% of malignant effusion had aneuploid. The relative cellular DNA content and the cell cycle distribution can provide valuable and decisive information. The study of chromosome also help the diagnosis in addition to cytological results.

Adult↗
PubMed1994

Role of tumor necrosis factor in neonatal sepsis.

In order to assess the role of tumor necrosis factor (TNF) in neonatal sepsis, plasma TNF levels were determined by a method using L929 cells at the time of septic work-up in 67 neonates. Thirty-three patients with sepsis were found to have significantly higher TNF levels (533.33 +/- 468.74 U/ml; 1 U corresponding to 1.67 pg recombinant TNF) as compared with 34 non-sepsis patients (100.0 +/- 188.97 U/ml) and 30 healthy newborns (27.33 +/- 16.17 U/ml, P < 0.05, respectively). The upper limit of normal plasma TNF levels was 60 U/ml and the best cutoff value for predicting neonatal sepsis was 160 U/ml. This had remarkable sensitivity (88%), specificity (82%), positive predictive value (83%), and negative predictive value (88%). Plasma TNF levels were significantly associated with the occurrence of shock, organ failure, scleroma and outcome. Thus, anti-TNF antibodies might be used in protecting newborns from septic death.

Acinetobacter Infections↗