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Biomedical subjects

Jin Choi

Publications and source records attributed to Jin Choi.

9 recordsLinked to original sources
PubMed2006

Cysteine-179 of IkappaB kinase beta plays a critical role in enzyme activation by promoting phosphorylation of activation loop serines.

IkappaB kinase beta (IKKbeta) subunit of IKK complex is essential for the activation of NF-kappaB in response to various proinflammatory signals. Cys-179 in the activation loop of IKKbeta is known to be the target site for IKK inhibitors such as cyclopentenone prostaglandins, arsenite, and antirheumatic gold compounds. Here we show that a mutant IKKbeta in which Cys-179 is substituted with alanine had decreased activity when it was expressed in HEK-293 cells, and TNF stimulation did not restore the activity. Phosphorylation of activation loop serines (Ser-177 and Ser-181) which is required for IKKbeta activation was reduced in the IKKbeta (C179A) mutant. The activity of IKKbeta (C179A) was partially recovered when its phosphorylation was enforced by coexpression with mitogen-activated protein kinase kinase kinases (MAPKKK) such as NF-kappaB inducing kinase (NIK) and MAPK/extracellular signal-regulated kinase kinase kinase 1(MEKK1) or when the serine residues were replaced with phospho-mimetic glutamate. The IKKbeta (C179A) mutant was normal in dimer formation, while its activity abnormally responded to the change in the concentration of substrate ATP in reaction mixture. Our results suggest that Cys-179 of IKKbeta plays a critical role in enzyme activation by promoting phosphorylation of activation-loop serines and interaction with ATP.

Adenosine Triphosphate↗
PubMed2006

[Disorder of AZF].

Explore the source record for details and available documents.

Base Sequence↗
PubMed2006

Zoom lens design for a novel imaging spectrometer that controls spatial and spectral resolution individually.

A novel imaging spectrometer can individually control spatial and spectral resolution by using zoom lenses as the foreoptics of the system and a focusing lens. By varying the focal length we can use the focusing lens to change the spatial and spectral dimensions; with the foreoptics, however, we can change only the spatial dimension. Therefore the spectral resolution and the spectral range are affected by the zoom ratio of the focusing lens, whereas the spatial resolution and the field of view are affected by the multiplication of the zoom ratios of the foreoptics and the focusing lens. By properly combining two zoom ratios, we can control the spectral resolution with a fixed spatial resolution or the spatial resolution with a fixed spectral resolution. For an imaging spectrometer with this novel zooming function, we used the lens module method and third-order aberration theory to design an initial four-group zoom system with an external entrance pupil for the focusing lens. Furthermore, using the optical design software CODE V, we obtained an optimized zoom lens with a focal-length range of 50 to 150 mm. Finally, the zoom system with its transmission grating in the Littrow configuration performs satisfactorily as the focusing lens of an imaging spectrometer in the wavelength range 450-900 nm.

Journal Article↗
PubMed2006

Reevaluation of azoospermic factor c microdeletions using sequence-tagged site markers with confirmed physical positions from the GenBank database.

OBJECTIVE: To investigate microdeletions and palindrome complexes in the azoospermic factor (AZF) c regions of the Y chromosome, by polymerase chain reaction (PCR) with sequence-tagged site (STS) markers with known physical positions, after verification of the exact physical locations of candidate STSs and exclusion of those that would give ambiguous results on PCR. DESIGN: Retrospective STS deletion study in infertile Japanese men. SETTING: University hospital and reproductive clinic. PATIENT(S): A total of 410 men with nonobstructive azoospermia and severe oligospermia (sperm concentrations of <5 x 10(6)/mL). INTERVENTION(S): Polymerase chain reaction was performed for all STS markers confirmed to be physically located in the partial AZFb and AZFc regions of the Y chromosome. All STSs were retrieved from the University of California at Santa Cruz database, and their location and specificity were verified. MAIN OUTCOME MEASURE(S): Presence or absence of appropriately sized PCR products. RESULT(S): Sixty-nine markers were retrieved, 32 of which were not specific to the long arm of the Y chromosome (Yq). The markers retained for test use were contiguous deletions classified as P1+P2 (AZFc) or P3 proximal/P1 (AZFb+c). The prevalence of accurately mapped microdeletions was 5.1% (21 of 410) in this patient population. CONCLUSION(S): Although noncontiguous deletions were observed, considerable confusion remained until the genome sequence was finally determined because many of the STSs were either repetitive sequences or polymorphic between individuals or races.

Animals↗
PubMed2006

Application of umbilical cord serum eyedrops for the treatment of dry eye syndrome.

PURPOSE: To investigate the efficacy of umbilical cord serum eyedrops for the treatment of severe dry eye syndrome. METHODS: Fifty-five eyes of 31 patients with severe dry eye syndrome were treated with umbilical cord serum eyedrops. Symptom scoring, tear film break-up time (BUT), Schirmer test, corneal sensitivity test, and corneal fluorescein staining were performed before and 1 and 2 months after treatment, and conjunctival impression cytology was performed before and 2 months after treatment. The concentrations of epidermal growth factor (EGF), vitamin A, and transforming growth factor-beta (TGF-beta) in umbilical cord serum and normal peripheral blood serum were measured. RESULTS: Two months after treatment, significant improvement was observed in symptom score (from 3.07 +/- 0.54 to 0.96 +/- 0. 58), BUT (from 3.96 +/- 1.56 to 5.45 +/- 2.54 seconds), and keratoepitheliopathy score (from 4.87 +/- 3.22 to 1.71 +/- 1.84) (P < 0.01). There was no statistically significant change in Schirmer and corneal sensitivity tests. In impression cytology, the grade of squamous metaplasia (from 2.35 +/- 0.72 to 1.44 +/- 0.69) and goblet cell density (from 80.91 +/- 31.53 to 154.68 +/- 43.06 cell/mm) improved significantly (P < 0.01). The mean concentrations of EGF, TGF-beta, and vitamin A were 0.48 +/- 0.09, 57.14 +/- 18.98, and 230.85 +/- 13.39 ng/mL in umbilical cord serum and 0.14 +/- 0.03, 31.30 +/- 12.86, and 372.34 +/- 22.32 ng/mL in peripheral blood serum, respectively. CONCLUSION: Umbilical cord serum contains essential tear components, and umbilical cord serum eyedrops are effective and safe for the treatment of severe dry eye syndrome.

Adult↗
PubMed2005

Pigmented-membrane formation on acrylic intraocular lenses after phacoemulsification.

PURPOSE: To report the formation of pigmented membranes on acrylic intraocular lenses (IOLs) after phacoemulsification and to determine the clinical characteristics of these pigmented membranes. DESIGN: Observational case series. METHODS: Four eyes of three patients were found to have pigmented membranes on their acrylic IOLs (Sensar AR40). Their medical records were reviewed. RESULTS: The pigmented membranes were observed at 4- to 9-month intervals after phacoemulsification. Their best-corrected Snellen visual acuity (BCVA) decreased by more than 2 lines, ranging from 20/63 to 20/40. After Nd:YAG laser treatment, BCVA improved 2 to 4 lines. At 5- to 12-week intervals after Nd:YAG laser treatment, recurrences of the pigmented membranes were observed with decreased BCVA. CONCLUSIONS: We have observed visually significant, recurrent, pigmented membrane formation in eyes implanted with Sensar AR40 acrylic IOLs. To the best of our knowledge, pigmented membranes on acrylic IOLs have not been described previously.

Acrylic Resins↗
PubMedDate not supplied

Outcome of cheilectomy in Legg-Calve-Perthes disease: minimum 25-year follow-up of five patients.

The authors report minimum 25-year follow-up results of cheilectomy performed in five hips affected by Legg-Calve-Perthes disease (LCPD) with hinged abduction. All five hips had a poor prognosis in terms of age at disease onset, treatment delay, hinged abduction, subluxation, and extensive head involvement. Cheilectomy, partial capital resection, was made along the indentation groove on the articular surface of the femoral head. Only the extruded portion of the femoral head was excised. Patients were placed in balanced suspension traction before and after surgery. Cheilectomy results were satisfactory during the early postoperative period (2-3 years) in terms of pain, range of motion, and limping. However, long-term results with a minimum follow-up of 25 years were unsatisfactory and showed poor hips in three, fair in one, and good in one. In addition, all five hips showed early evidence of osteoarthritic change (when patients were in their 30s). These results show that cheilectomy is not effective at preventing the early appearance of osteoarthritic change in LCPD hips with a deformed head and hinged abduction.

Child↗