Biomedical subjects

James Chou

Publications and source records attributed to James Chou.

4 recordsLinked to original sources

PubMed2006

Protein structure similarity from Principle Component Correlation analysis.

BACKGROUND: Owing to rapid expansion of protein structure databases in recent years, methods of structure comparison are becoming increasingly effective and important in revealing novel information on functional properties of proteins and their roles in the grand scheme of evolutionary biology. Currently, the structural similarity between two proteins is measured by the root-mean-square-deviation (RMSD) in their best-superimposed atomic coordinates. RMSD is the golden rule of measuring structural similarity when the structures are nearly identical; it, however, fails to detect the higher order topological similarities in proteins evolved into different shapes. We propose new algorithms for extracting geometrical invariants of proteins that can be effectively used to identify homologous protein structures or topologies in order to quantify both close and remote structural similarities. RESULTS: We measure structural similarity between proteins by correlating the principle components of their secondary structure interaction matrix. In our approach, the Principle Component Correlation (PCC) analysis, a symmetric interaction matrix for a protein structure is constructed with relationship parameters between secondary elements that can take the form of distance, orientation, or other relevant structural invariants. When using a distance-based construction in the presence or absence of encoded N to C terminal sense, there are strong correlations between the principle components of interaction matrices of structurally or topologically similar proteins. CONCLUSION: The PCC method is extensively tested for protein structures that belong to the same topological class but are significantly different by RMSD measure. The PCC analysis can also differentiate proteins having similar shapes but different topological arrangements. Additionally, we demonstrate that when using two independently defined interaction matrices, comparison of their maximum eigenvalues can be highly effective in clustering structurally or topologically similar proteins. We believe that the PCC analysis of interaction matrix is highly flexible in adopting various structural parameters for protein structure comparison.

Algorithms↗

PubMed2004

Cementodentinal tear: a case report with 7-year follow-up.

BACKGROUND: Cemental tears are an uncommon form of root fracture that can lead to rapid localized attachment loss. Typically, the separation of the fragment occurs at the cementodentinal junction. In this report, we present a case of periodontal involvement associated with a cemental tear-like fragment that proved to be a cementodentinal tear. We also review the literature on the clinical presentation of cemental tear associated periodontal lesions. METHODS: A 52-year-old male presented with acute pain on the maxillary right second premolar. Clinically, probing depth of 7 mm and inflammation were noted on the distal aspect of tooth #4. Radiographic examination revealed separation of cervical root structure on the distal aspect of the tooth, involving two-thirds of the root length. The root fragment was removed, and the localized defect was treated by open flap debridement along with scaling and root planing. The patient was then placed on a regular periodontal maintenance schedule. RESULTS: A postoperative probing depth of 2 mm with 1 mm recession was recorded at 3 months, and maintained for 7 years. Histological examination indicated that the detached root fragment contained dentin with overlying acellular cementum and associated periodontal ligament tissue. The fragment was estimated to represent as much as 20% of the total root surface area. CONCLUSION: Moderate to severe periodontal attachment loss associated with cemental or cementodentinal tears, even ones constituting a significant portion of the root surface, can be successfully treated with conventional periodontal surgical procedures and maintained long term with a proper maintenance regimen.

Bicuspid↗

PubMedDate not supplied

Predictors of aggression on the psychiatric inpatient service.

Patients with severe mental illness are at increased risk to commit acts of aggression in the inpatient hospital setting. Aggressive behaviors have severe negative consequences for the patient, victims, clinical staff, and the therapeutic community as a whole. While risk factors of community and inpatient aggression overlap, many predictive factors diverge between the two settings. For example, while medication noncompliance has been a robust predictor of community aggression, this factor has little predictive value for inpatient settings where patients' pharmacotherapy is closely monitored. Relatively fewer investigators have examined a wide range of predictive factors associated with aggressive acts committed on the psychiatry inpatient service, often with conflicting results. The present study examined demographic, clinical, and neurocognitive performance predictors of self, other, object, and verbal aggressiveness in 118 acute inpatients. Results revealed that the arrival status at the hospital (voluntary vs involuntary), female gender, and substance abuse diagnosis were predictors of verbal aggression and aggression against others. Impaired memory functioning also predicted object aggression. Fewer symptoms, combined with higher cognition functioning, however, were significant predictors of self-aggressive acts committed on the inpatient service. The need for relating predictors of specific types of aggressiveness in schizophrenia is discussed.

Adult↗

PubMedDate not supplied

Fabrication of a laser-welded fixed-detachable prosthesis for immediate loading.

Immediate loading of dental implants in completely edentulous patients is receiving great attention. Standard surgical protocol is used with primary stabilization of the implants as a goal. The restorative dentist must coordinate with the surgeon and the laboratory technician to make immediate loading a reality for the completely edentulous patient. This article describes a technique developed to fabricate an immediately loaded fixed-detachable prosthesis using laser welding technology. Advantages, which are applicable to various implant systems and patients, are discussed.

Dental Implantation, Endosseous↗