PubMed Health⌕ Search

Biomedical subjects

Jennifer Kim

Publications and source records attributed to Jennifer Kim.

7 recordsLinked to original sources
PubMed2003

Positive influence of AP-2alpha transcription factor on cadherin gene expression and differentiation of the ocular surface.

The family of transcription factors Activating protein-2 (AP-2) are known to play important roles in numerous developmental events, including those associated with differentiation of stratified epithelia. However, to date, the influence of the AP-2 genes on endogenous gene expression in the stratified epithelia and how this affects differentiation has not been well defined. The following study examines the detailed expression of the AP-2alpha and AP-2beta proteins in the stratified epithelia of the ocular surface, including that in the cornea and developing eyelids. The effect of altered levels of the AP-2alpha gene on ocular surface differentiation was also examined using a corneal epithelial cell line and AP-2alpha chimeric mice. Immunolocalization studies revealed that, while AP-2beta was broadly expressed throughout all cell layers of the stratified corneal epithelium, AP-2alpha expression was confined to cell compartments more basally located. AP-2alpha was also highly expressed in the less differentiated cell layers of the eyelid epidermis. Overexpression of the AP-2alpha gene in the corneal cell line, SIRC, resulted in a dramatic change in cell phenotype including a clumping growth behavior that was distinct from the smooth monolayer of the parent cell line. Accompanying this change was an up-regulation in levels of the cell adhesion molecule, N-cadherin. Examination of the ocular surface of AP-2alpha chimeric mice, derived from a mixed population of AP-2alpha-/- and AP-2alpha+/+, revealed that a down-regulation in E-cadherin expression is correlated with location of the AP-2alpha-/- null cells. Together, these findings demonstrate that AP-2alpha participates in regulating differentiation of the ocular surface through induction in cadherin expression.

Animals↗
PubMed2002

ERAAP customizes peptides for MHC class I molecules in the endoplasmic reticulum.

The ability of killer T cells carrying the CD8 antigen to detect tumours or intracellular pathogens requires an extensive display of antigenic peptides by major histocompatibility complex (MHC) class I molecules on the surface of potential target cells. These peptides are derived from almost all intracellular proteins and reveal the presence of foreign pathogens and mutations. How cells produce thousands of distinct peptides cleaved to the precise lengths required for binding different MHC class I molecules remains unknown. The peptides are cleaved from endogenously synthesized proteins by the proteasome in the cytoplasm and then trimmed by an unknown aminopeptidase in the endoplasmic reticulum (ER). Here we identify ERAAP, the aminopeptidase associated with antigen processing in the ER. ERAAP has a broad substrate specificity, and its expression is strongly upregulated by interferon-gamma. Reducing the expression of ERAAP through RNA interference prevents the trimming of peptides for MHC class I molecules in the ER and greatly reduces the expression of MHC class I molecules on the cell surface. Thus, ERAAP is the missing link between the products of cytosolic processing and the final peptides presented by MHC class I molecules on the cell surface.

Amino Acid Sequence↗
PubMed2002

The role of abdominal computed tomography scanning in patients with non-traumatic abdominal symptoms.

OBJECTIVES: To describe the non-traumatic clinical settings in which abdominal computed tomography (CT) is used and to determine its diagnostic utility. METHODS: A retrospective descriptive study of consecutive non-traumatic adult patients who underwent abdominal CT in a university hospital emergency department (ED). Radiology reports and patient charts were reviewed. The indication for each CT was determined by two reviewers. Indications were described as specific (e.g. "rule-out" appendicitis) or non-specific (e.g. abdominal pain). CT results were classified as positive, negative (normal or no new information) or indeterminate (technical limitations). For those with specific indications, positive results were further subdivided into supportive (of the clinical suspicion) or non-supportive (abnormal but suggesting an alternative diagnosis). The clinical course and results of subsequent diagnostic procedures were used to confirm CT results for admitted patients. Incidental CT findings were recorded. RESULTS: 177 patients were entered; mean age was 58 years; 48% were men. The most frequent indications ("rule-outs") were aortic disorders (23%), abscess (16%), and diverticulitis (14%). In patients with specific indications (n=160), 44% of the CT results supported the indication, 13% suggested an alternative diagnosis (non-supportive), 41% were negative, and 3% were indeterminate. In admitted patients (n=129), CT findings were contradicted in 6%. CONCLUSIONS: Adult ED patients undergo abdominal CT for a variety of non-traumatic indications. Findings in less than half support the pre-test clinical suspicion and an alternative previously unsuspected diagnosis is suggested in 13%. Follow-up is inconsistent with CT results in a small but significant number of cases.

Abdominal Pain↗
PubMedDate not supplied

The effect of subcutaneously administered low-molecular-weight heparin on microarterial thrombosis in the rat.

OBJECTIVE: To examine the effect of administration of a low-molecular-weight heparin derivative, enoxaparin, on the rate of arterial thrombosis in a rat model. STUDY DESIGN: Prospective, randomized, blinded study. METHODS: A standard microarterial anastomosis tuck injury was created in both femoral arteries of 25 Long Evans retired breeder rats. Thirteen animals received a subcutaneous injection of 50 IU/kg of enoxaparin 2 hours before the procedure, while 12 control animals received vehicle (isotonic sodium chloride solution) alone. Sites of injury/repair were assessed 2 hours after the procedure for anastomotic patency or thrombosis. RESULTS: Six (23%) of 26 vessels in the drug-treated group developed an arterial thrombosis at the site of repair, while 6 (25%) of 24 vessels in the control group developed thrombosis. There was no statistically significant difference at the 95% confidence limit between the 2 groups based on a comparison-of-proportions test. CONCLUSION: The preoperative subcutaneous administration of 50 IU/kg of enoxaparin did not alter the rate of arterial thrombosis following the creation of a thrombogenic tuck injury/repair of the rat femoral artery.

Animals↗
PubMedDate not supplied

Muscle tissue engineering for partial glossectomy defects.

BACKGROUND: Tongue reconstruction represents a difficult reconstructive problem, based on the tongue's complex multimodality function. Existing methods of tongue reconstruction often result in significant deficits in speech and deglutition. A functional neotongue requires adequate soft tissue bulk and restoration of coordinated muscle function. Tissue engineering, a scientific approach that allows introduction of isolated cell populations of interest within 3-dimensional polymer scaffolds to create new tissue, may allow the generation of more highly functional tissue in tongue reconstruction. OBJECTIVES: To apply muscle-tissue engineering techniques in the reconstruction of partial glossectomy defects in rats, and to compare the gross and histological nature of tissue found after reconstruction of the hemiglossectomy defect with acellular vs tissue-engineered composite material. MATERIALS AND METHODS: Thirty mature Lewis rats underwent a left-sided mucosa-sparing partial glossectomy. The defects were then filled with 1 of the following 3 substances: isotonic sodium chloride solution, a collagen-rich hydrogel, or hydrogel containing a suspension of neonatal myoblasts from syngeneic rats. The animals were killed after 6 weeks and the tongues were harvested. The control and operated-on tongue halves were evaluated for weight differences and histological features. RESULTS: The group receiving the hydrogel-myoblast composite injections demonstrated a statistically significant increase in tongue weight of the operated-on side compared with the control side. In contrast, the isotonic sodium chloride solution and hydrogel groups demonstrated loss of tongue weight. These findings correlated with the results of the histological evaluation. Hemitongues from the composite group demonstrated formation of new tissue with areas of musclelike tissue extending from islands of residual hydrogel, and we found evidence of neovascularization and possible neurotization. In contrast, the isotonic sodium chloride solution group exhibited dense fibrous scar with loss of muscle architecture and dramatic loss of tongue volume. The hydrogel group demonstrated preservation of tongue volume with persistent islands of gel, but no clear evidence of new tissue formation. CONCLUSIONS: The introduction of a hydrogel into the rat hemiglossectomy pocket appears to promote volume preservation and/or muscle regeneration. The addition of myoblasts suspended in collagen gel supports the development of new tissue that preserves weight and volume after hemiglossectomy and may possess muscle properties similar to the tissue desired. This tissue-engineering approach represents a promising new strategy in tongue reconstruction and merits further investigation into the possible functional advantages it offers compared with current techniques.

Animals↗