Biomedical subjects

Ning Sun

Publications and source records attributed to Ning Sun.

22 records · Page 2Linked to original sources

PubMed2003

The management of old urethral injury in young girls: analysis of 44 cases.

BACKGROUND/PURPOSE: Traumatic urethral injury in girls is rare, and there is no consensus on its management. The authors report their 22-year experience. METHODS: Forty girls presented with urethrovaginal fistula. Twenty-six girls presented with cystostomy tube in place, whereas 17 girls presented with complete urinary incontinence. Incision and dilatation of the obliterated urethra was carried out in 7 patients. Vaginal repair of urethrovaginal fistula was performed in 4 patients. Transpubic reconstruction of the urethra using a modified Young-Dees-Leadbetter procedure with simultaneous repair of the urethrovaginal fistula was performed in 35 patients (once in 27, twice in 5, and 3 times in 3 patients). RESULTS: Follow-up in 40 girls averaged 3.5 years. Twenty-nine patients have regained normal urinary control, and 11 patients have mild stress urinary incontinence. Four patients were lost to follow-up. CONCLUSIONS: Simple dilation of the obliterated urethra can reestablish satisfactory urethral patency if the obliterated segment is short. The vaginal approach to urethrovaginal fistula may be successful in patients without concomitant urethral stricture or in those with stricture amenable to simple dilation. The transpubic approach remains the method of choice for repairing complete urethral disruption and severe urethral stricture, especially when associated with urethrovaginal fistula.

Adolescent↗

PubMed2003

Evaluation of light regulatory potential of Calvin cycle steps based on large-scale gene expression profiling data.

Although large-scale gene expression data have been studied from many perspectives, they have not been systematically integrated to infer the regulatory potentials of individual genes in specific pathways. Here we report the analysis of expression patterns of genes in the Calvin cycle from 95 Arabidopsis microarray experiments, which revealed a consistent gene regulation pattern in most experiments. This identified pattern, likely due to gene regulation by light rather than feedback regulations of the metabolite fluxes in the Calvin cycle, is remarkably consistent with the rate-limiting roles of the enzymes encoded by these genes reported from both experimental and modeling approaches. Therefore, the regulatory potential of the genes in a pathway may be inferred from their expression patterns. Furthermore, gene expression analysis in the context of a known pathway helps to categorize various biological perturbations that would not be recognized with the prevailing methods.

Arabidopsis↗

PubMed2002

Differential induction of p53 in immature and adult rat brain following lithium-pilocarpine status epilepticus.

Activation of the tumor suppressor gene, p53, has been strongly implicated in selective neuronal cell death. This study investigated p53 expression in the immature and adult rat brain following status epilepticus induced by the administration of lithium-pilocarpine (LPSE). Both p53 mRNA and protein were examined in relation to neuronal degeneration using in situ hybridization and immunohistochemistry, respectively. Injured cells with eosinophilic cytoplasm with increased p53 mRNA were observed in hippocampal subfields, piriform cortex, amygdala and thalamus. p53 mRNA levels reached a peak by 8 h and returned to baseline by 24 h after the onset of LPSE. The magnitude of p53 mRNA induction was greatest in 21-day-old rats. In contrast to the cellular expression pattern of p53 mRNA, immunohistochemistry demonstrated that p53 protein was increased in all of the eosinophilic cells. Further, double-labeling studies revealed that p53 protein was elevated in neurons that were degenerating. This was supported by colocalization of activated caspase 3 in some cells with damaged DNA. These results provide additional evidence for a critical role for the p53 pathway in excitotoxic neuronal cell death due to status epilepticus.

Aging↗

PubMed2001

A Model for Calculating Electrostatic Interactions between Colloidal Particles of Arbitrary Surface Topology.

A numerical model for calculating the electrostatic interaction between two particles of arbitrary shape and topology is described. A key feature of the model is a generalized discretization program, capable of simulating any desired analytical shape as a set of flat, triangular elements. The relative sizes of the elements are adjusted using a density function to better match the desired shape and the spatial variation of the electrical surface properties on each particle. The distribution of either surface potential or surface charge density is then calculated using a boundary element approach to solve the linearized Poisson-Boltzmann equation. Example interaction energy profiles are calculated for three different types of roughness-bumps, pits, and surface waves. It is found that the interaction energy between rough particles remains different from that between two equivalent smooth spheres at all separations, even for gap widths much larger than either the solution Debye length or the characteristic roughness size. This behavior at large gap widths arises from the nature of the decay of the electric potential away from each particle. In addition, the magnitude of the roughness effect is found to depend greatly on the size and shape of the nonuniformity as well as the electrostatic boundary conditions. For example, for a sphere containing asperities of height equal to 0.2 times the particle radius, the interaction energy can be as much as 50% greater than that between two equivalent spheres under the condition of constant surface potential. At constant surface charge density, the ratio of the interaction energies between rough and smooth spheres was found to either diverge or become zero as contact between the two particles is approached, depending on the nature of the roughness. Changes of this magnitude could clearly have a substantial impact on the stability behavior of a dispersion of such particles. Copyright 2001 Academic Press.

Journal Article↗