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Biomedical subjects

C Sun

Publications and source records attributed to C Sun.

227 records · Page 13Linked to original sources
PubMed1970

On the size of the DNA in the mammalian chromosome. Structural subunits.

Alkaline degradation of mammalian DNA indicates that the molecule exists in the chromosome as an array of structural subunits. The size of the subunit of single-stranded DNA is circa 5 x 10(8) daltons, and it is of sufficient length to contain a number of synthetic units, replicons. The upper size limit of the multicomponent structure is in excess of 10(10) daltons. Mammalian cells of three different origins have been shown to contain the same basic structural DNA components and these components exist throughout the cell cycle. The nature of the links between the subunits is not known.

Animals↗
PubMedDate not supplied

Knowledge-based method for segmentation and analysis of lung boundaries in chest X-ray images.

We present a knowledge-based approach to segmentation and analysis of the lung boundaries in chest X-rays. Image edges are matched to an anatomical model of the lung boundary using parametric features. A modular system architecture was developed which incorporates the model, image processing routines, an inference engine and a blackboard. Edges associated with the lung boundary are automatically identified and abnormal features are reported. In preliminary testing on 14 images for a set of 18 detectable abnormalities, the system showed a sensitivity of 88% and a specificity of 95% when compared with assessment by an experienced radiologist.

Algorithms↗
PubMedDate not supplied

Syntheses of 2-alkylamino- and 2-dialkylamino-4,6-diarylpyridines and 2,4,6-trisubstituted pyrimidines using solid-phase-bound chalcones.

Several substituted 2- and 4-hydroxyacetophenones are linked to Wang resin via a modified Mitsunobu protocol. These resin-bound acetophenones are condensed with aromatic aldehydes, and the resulting chalcones 5 are used for the synthesis of 2-dialkylamino- (9a-d) and 2-alkylamino-4,6-diarylpyridines (11a-f), and 2-alkyl-4,6-diaryl- (14a) and 2,4,6-triarylpyrimidines (14b,c) in a manner suitable for combinatorial applications.

Acetophenones↗
PubMedDate not supplied

Structural basis for binding of Smac/DIABLO to the XIAP BIR3 domain.

The inhibitor-of-apoptosis proteins (IAPs) regulate programmed cell death by inhibiting members of the caspase family of enzymes. Recently, a mammalian protein called Smac (also named DIABLO) was identified that binds to the IAPs and promotes caspase activation. Although undefined in the X-ray structure, the amino-terminal residues of Smac are critical for its function. To understand the structural basis for molecular recognition between Smac and the IAPs, we determined the solution structure of the BIR3 domain of X-linked IAP (XIAP) complexed with a functionally active nine-residue peptide derived from the N terminus of Smac. The peptide binds across the third beta-strand of the BIR3 domain in an extended conformation with only the first four residues contacting the protein. The complex is stabilized by four intermolecular hydrogen bonds, an electrostatic interaction involving the N terminus of the peptide, and several hydrophobic interactions. This structural information, along with the binding data from BIR3 and Smac peptide mutants reported here, should aid in the design of small molecules that may be used for the treatment of cancers that overexpress IAPs.

Amino Acid Sequence↗
PubMedDate not supplied

Cost-benefit of trained transport teams: estimates for head-injured children.

INTRODUCTION: Care during transport influences the outcome of head-injured children. Secondary adverse events, e.g., hypotension and hypoxia, worsen morbidity and mortality. Trained transport teams lower the incidence of such secondary "insults." OBJECTIVE: To estimate the cost-benefit of improved care from trained escorts. METHODS: The setting was a provincial air ambulance service during transition to trained pediatric escort paramedics. A retrospective review of transport and hospital records for a 12-month period was conducted. All children with head injuries (n = 43) transported to tertiary care [11 by untrained escorts (UE), 32 by trained escorts (TE)] were enrolled. Severity of injury was classified by Glasgow Coma Score (GCS); incidence of adverse events was counted and cost of change of severity resulting from preventable insults was estimated using published care costs. RESULTS: There were 13 preventable insults in six patients (55%) in the UE group and five preventable insults in four patients (12%) in the TE group (p<0.05). Among those in the UE group, two changed in severity from moderate to severe, one moderate worsened (decrease in GCS of 2 or more), and two severe worsened. In the TE group, there were no changes >1. Cost-benefit estimates based on change in severity were $136,000 (median) to $238,000 (mean). CONCLUSION: Significant cost-benefit likely accrues from training escorts who transport children with significant head injuries to tertiary care.

Canada↗
PubMedDate not supplied

Characterization of the mutations of the K-ras, p53, p16, and SMAD4 genes in 15 human pancreatic cancer cell lines.

Human pancreatic cancer is one of the most malignant diseases in the world. In order to save patients with pancreatic cancer, it is necessary to develop novel methods for treatment. For such a purpose, a series of well-characterized cancer cell lines are of great help for in vitro studies that are generally the first step in approaching the invention of novel methods for treatment. In the present study, we analyzed 15 human pancreatic cancer cell lines for genetic alterations of the K-ras, p53, p16, and SMAD4 genes, which are very frequent targets for mutation in pancreatic cancer; these cell lines are useful resources in cancer research.

Adenocarcinoma↗
PubMedDate not supplied

In vitro chemopreventive efficacy screening using human keratinocytes and the in vivo data correlation.

Agents with potential cancer preventive activity were screened for efficacy in the Human Epidermal Cell (HEC) Assay. The HEC Assay measures inhibition of propane sultone-induced changes in the growth and/or differentiation in early passage keratinocyte cultures. The assay biomarkers were calcium tolerance, growth inhibition, and involucrin induction. The HEC Assay also provides information on the cytotoxicity of the agents following acute and chronic exposure. Agents were evaluated at non-toxic doses in the HEC Assay. The HEC Assay has been used to screen twenty-eight agents for chemopreventive efficacy. A positive response in one or more endpoints of the HEC Assay correlates 100% (16/16) with a positive response in one or more of the animal cancer prevention models (J. Cell. Biochem., 26S:29-53, 1996). The overall sensitivity for predicting efficacy in animals is 84%. The available data suggest that a positive assay response appears to be highly predictive of efficacy in vivo.

Animals↗
PubMedDate not supplied

The cost-benefit of pulse-oximeter use in the prehospital environment.

INTRODUCTION: Pulse-oximetry has proven clinical value in Emergency Departments and Intensive Care Units. In the prehospital environment, oxygen is given routinely in many situations. It was hypothesized that the use of pulse oximeters in the prehospital setting would provide a measurable cost-benefit by reducing the amount of oxygen used. METHODS: This was a prospective study conducted at 12 ambulance stations (average transport times > 20 minutes). Standard care protocols and paramedic assessments were used to determine which patients received oxygen and the initial flow rate used. Pulse-oximetry measurements (SpO2) were then taken. If SpO2 fell below 92% or rose above 96% (except in patients with chest pain), oxygen (O2) flow rates were adjusted. Costs of oxygen use were calculated: volume that would have been used based on initial flow rate; and volume actually used based on actual flow rates and transport time. RESULTS: A total of 1,907 patients were recruited. Oximetry and complete data were obtained on 1,787 (94%). Of these, 1,329 (74%) received O2 by standard protocol: 389 (27.5%) had the O2 flow decreased; 52 had it discontinued. Eighty-seven patients (6%) not requiring O2 standard protocol were hypoxemic (SpO2 < 92%) by oximetry, and 71 patients (5%) receiving oxygen required flow rate increases. Overall, O2 consumption was reduced by 26% resulting in a cost-savings of $0.20/patient. Prehospital pulse-oximetry allows unnecessary or excessive oxygen therapy to be avoided in up to 55% of patients transported by ambulance and can help to identify suboptimally oxygenated patients (11%). CONCLUSIONS: Rationalizing the O2 administration using pulse-oximetry reduced O2 consumption. Other health care savings likely would result from a reduced incidence of suboptimal oxygenation. Oxygen cost-saving justifies oximeter purchase for each ambulance annually where patient volume exceeds 1,750, less frequently for lower call volumes, or in those services where the mean transport time is less than the 23 minute average noted in this study.

Ambulances↗
PubMedDate not supplied

The cost of family-oriented communication before air medical interfacility transport.

INTRODUCTION: Family-oriented communication with parents by transport teams eases the stress associated with transferring children to tertiary care. This study was conducted to determine the duration of family-oriented visits and whether the visit contributed significant cost to the mission. METHOD: Data collection was prospective and double-blind; questions were incorporated into another study. Subjects were infants or children requiring assisted ventilation and air transport to tertiary care. Time from completion of stabilization to departure and reasons for any delay were recorded. Cost of contact time longer than 20 minutes (total acceptable time for family visit and transfer to vehicle) was calculated at paramedic overtime at $0.82/minute and aircraft wait time at $200/hour if incurred. RESULTS: Forty-six patients were enrolled. In 16 cases (35%), time between completing stabilization and hospital departure exceeded 20 minutes, with "family visit" listed as the explanation. Nine of these visits incurred overtime, and two incurred aircraft wait costs. Total costs for providing communication visits more than 10 minutes long were $607 or approximately $13 per patient. CONCLUSION: The costs for visit time longer than 10 minutes are small compared with the documented benefits of family-oriented communication. However, transport personnel must be mindful of the potential to incur additional cost through overtime, aircraft wait time, or pilot replacement.

Air Ambulances↗