Biomedical subjects

Y R Chen

Publications and source records attributed to Y R Chen.

At least 73 records · Page 4Linked to original sources

PubMed1999

c-Jun N-terminal kinase mediates apoptotic signaling induced by N-(4-hydroxyphenyl)retinamide.

N-(4-Hydroxyphenyl)retinamide (4-HPR), a retinoic acid analog, induces apoptosis in several cell types. The mechanism by which 4-HPR initiates apoptosis remains poorly understood. We examined the effects of 4-HPR on two prostate carcinoma cell lines, LNCaP (an androgen-sensitive, p53(+/+) cell line) and PC-3 (an androgen-insensitive, p53(-/-) cell line). 4-HPR caused sustained c-Jun N-terminal kinase (JNK) activation and apoptosis in LNCaP cells but not in PC-3 cells at the dosages tested. Activation of JNK by 4-HPR was independent of caspases because a pan-caspase inhibitor failed to suppress JNK activation. Ultraviolet-C and gamma-radiation induced JNK activation in both LNCaP and PC-3 cells, suggesting that the failure of PC-3 cells to respond to 4-HPR was due to defects upstream of the JNK pathway. Furthermore, gamma-radiation-induced JNK activation was suppressed by an antioxidant, but 4-HPR-induced JNK activation was not, indicating that these two stimuli induced JNK activation through different mechanisms. Forced expression of JNK1, but not a JNK1 mutant, caused apoptosis in both LNCaP and PC-3 cells, suggesting that p53 is not required for JNK-mediated apoptosis. 4-HPR-induced apoptosis in LNCaP cells was suppressed by curcumin, which inhibits JNK activation. Expression of dominant-negative mutants in the JNK pathway also inhibited 4-HPR-induced apoptosis in human embryonic kidney 293 cells. Collectively, these results suggest that the JNK pathway mediates 4-HPR-induced apoptotic signaling.

Antineoplastic Agents↗

PubMed1999

Phenomenology of mania: evidence for distinct depressed, dysphoric, and euphoric presentations.

OBJECTIVE: A substantial number of manic episodes include conspicuous depressive symptoms. Manic episodes have been clinically classified a posteriori using preset criteria. The aim of this study was to investigate the possibility that there might be a natural division of manic episodes into clinical types. METHOD: One hundred and five inpatients met Research Diagnostic Criteria and DSM-III-R criteria for manic episodes and were rated before institution of pharmacological treatment. The authors conducted a factor analysis of 37 behavior rating items from the Schedule for Affective Disorders and Schizophrenia. The resulting factors were used as independent variables in a cluster analysis of the patients. RESULTS: This analysis revealed four factors corresponding to manic activation, depressed state, sleep disturbance, and irritability/paranoia. Cluster analysis separated the patients into two groups. One included patients with major depressive disorder and mania. Blind, a priori clinical classification into classic and mixed mania (mania plus depression) showed that all of the patients in the depressed cluster, and about 40% of those in the nondepressed cluster, were in a mixed state according to clinical criteria. Comparison of the clinically mixed and nonmixed patients in the nondepressed cluster revealed that the mixed patients in that cluster had higher scores for items related to anger, worry, dysphoria, and irritability. CONCLUSIONS: These data suggest that manic episodes can be naturalistically classified as classic (predominately euphoric), dysphoric, or depressed.

Adult↗

PubMed1999

Assessment of orientation: relationship between informant report and direct measures.

Although informant reports of everyday functioning are often used in dementia assessments, the actual correspondence between such indirect reports of functioning and actual performance has not been examined. Orientation results on the Dementia Questionnaire for Mentally Retarded Persons were compared to those obtained in direct assessment of orientation of 138 adults with mental retardation. Fair to good agreement was found between informant report and direct assessment. However, for some orientation items, nonverbal IQ, cause of mental retardation, and age affected the level of agreement. Thus, both informant report and direct measures of orientation are necessary in dementia assessments, and further work is needed on informant scale validation.

Activities of Daily Living↗

PubMed1999

Mandibular lengthening by distraction osteogenesis in children--a one-year follow-up study.

OBJECTIVE: The present study was undertaken to document whether mandibular length could be increased by distraction osteogenesis in children and what happens to the mandibular position 1 year after the distraction. METHODS: Five patients with hemifacial microsomia (four unilateral, one bilateral) had distraction osteogenesis performed to lengthen the mandible. All patients had cephalometric and panoramic radiographs obtained before and 3, 6, and 12 months after the distraction osteogenesis. RESULTS: The total mandibular length (Co-Gn) on the affected side was increased by 11.2 mm after the distraction and remained stable during a 1-year observation period. However, the increased mandibular length tended to move the chin downward (8 mm) more than forward (2 mm) during the same period. CONCLUSIONS: Distraction osteogensis can be used to lengthen the hypoplastic mandible. However, most of the increased mandibular length moved the chin downward more than forward.

Activator Appliances↗

PubMed1999

Augmentation of the nasal floor with Surgicel in primary lip repair: a prospective study showing no efficacy.

The symmetry of the alar base and the nasal floor is very important in achieving a satisfactory result in primary lip and nasal reconstruction during cleft lip repair. The skeletal base of the nasal pyramid is usually hypoplastic even in incomplete clefts. A periosteal pocket filled with Surgicel can facilitate blood clot formation and can theoretically stimulate bone formation, thereby improving the asymmetry of the bone base. To test this hypothesis, a prospective study was performed in 64 primary lip repairs by comparing the effect of subperiosteal nasal floor augmentation with Surgicel. From February 1989 to June 1993, 64 patients with incomplete cleft lips (excluding occult cleft lip and complete clefts with Simonart's band) were operated by the same surgeon. The patients were divided randomly into two groups. One group had subperiosteal nasal floor augmentation with Surgicel and the other group did not. The lip repair was a rotation-advancement cheiloplasty with primary closed rhinoplasty of the tip and ala. In the first group, a subperiosteal pocket was created under the cleft alar base and the nasal floor. The pocket was filled with Surgicel up the point where the level of the alar base and the nasal floor was symmetrical with the noncleft side. The control group underwent a similar procedure, less the creation of the subperiosteal pocket and the use of Surgicel. All patients were followed for at least 3 years and their photographs were used to compare and analyze the results of their nasal correction. Critical attention was paid to the symmetry of their nasal floor and alar base. The results were evaluated by at least two plastic surgeons for consistency. The data indicate that the control group showed a higher number of subjects with asymmetry (10 of 32) compared with the study group (8 of 32). However, there was no statistical significance to the findings. Two patients in the study group who received Surgicel developed hypertrophic lip scars. This study, although unable to determine statistically the contributory affect of Surgicel in primary nasal reconstruction, does show a possible benefit from the use of osteogenic materials in the primary management of the deficient nasal floor. Hypertrophic scars developed by 2 patients in the study group may point to a possible soft-tissue reaction to the use of Surgicel in primary lip and nasal repair.

Cellulose, Oxidized↗

PubMed1999

Cleft of the lip and palate in twins.

BACKGROUND: Cleft lip and palate is one of the most common congenital anomalies in Taiwan. Its etiology remains unknown for the majority of the patients. The study of twins is a classic method for evaluating the relative roles of genetic and environmental factors in the formation of the anomaly. METHODS: In this study, 37 pairs of twins and one set of triplets with cleft lip and palate were evaluated. Clinical data were collected for zygosity determination and analysis of etiologic factors. The concordance rate and heritability index were assessed. RESULTS: The results showed that the concordance rate was 26% for all twins and 57% among the monozygotic pairs, which is higher than those rates for the Caucasian population. The heritability index was 53%, higher than the other reports as well. The influence of the environment could not be ruled out. CONCLUSION: The results confirm a strong genetic role in the etiology of clefts in our patients. Environmental factors were acting as well. The findings in this study support the multifactorial threshold model in the development of cleft lip and palate.

Adolescent↗

PubMed1999

Bilateral coronoid process hyperplasia with limitation on mouth opening: case report.

Coronoid process hyperplasia with limitation of mouth opening is rare. The pathology is often ignored, but it can be easily detected using dental panoramic view of x-ray films. Definition of the coronoid process hyperplasia can be made by measuring the height of coronoid process and the ratio of coronoid/condyle height on lateral cephalometric x-ray film. Etiology of the coronoid process hyperplasia can be congenital or acquired. Differentiation of the diagnosis may be difficult. The congenital type occurs at early age with clinical manifestations. Proposed hypotheses for the formation of coronoid process hyperplasia include increased activity within the temporalis muscle from conditions such as functional stress, compression, and tension. For patients with coronoid process hyperplasia and restriction on mouth opening, conservative treatment should first be attempted. Surgical treatment is considered if conservative treatment fails. Coronoidectomy with early mobilization and aggressive physiotherapy corrects the problem. We present a patient with coronoid process hyperplasia with limitation of mouth opening who was successfully treated.

Abnormalities, Multiple↗

PubMed1999

Basic fibroblast growth factor enhanced LAK cell cytotoxicities against human bladder neoplasm cells.

AIM: To study the effects of basic fibroblast growth factor (bFGF) on the proliferation of lymphokine-activated killer (LAK) cells from patients with bladder cancer and LAK cells cytolysis against bladder tumor cells. METHODS: LAK cell proliferation was assayed in the presence of various concentrations of bFGF combined with interleukin-2 (IL-2) by cell count. Cytotoxicity of LAK cells against bladder cancer cell line EJ cells and bladder tumor cells (BTC) from patients was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. RESULTS: The proliferation of peripheral blood monocytes (PBMC) was inhibited by bFGF 5 micrograms.L-1. bFGF did not affect the stimulation of LAK cells induced by IL-2. The LAK cell numbers in the combination of IL-2 with bFGF were not significantly different compared with that treated with IL-2 alone. bFGF enhanced cytotoxicity of LAK cells against bladder cancer cell line EJ cells or BTC, respectively. CONCLUSION: Although the proliferation of PBMC was inhibited by bFGF, bFGF increased LAK cell cytotoxicity against bladder neoplasm cells.

Carcinoma, Transitional Cell↗

PubMed1999

Maxillary growth after palatal denudation: an animal experiment.

BACKGROUND: Palate surgery at an early age may cause retardation of maxillary growth. The second intention healing of the raw bone surface created on the palate is considered to be the cause of the growth retardation. The animal experiment in this study was designed to evaluate this effect. METHODS: Four-week-old Sprague-Dawley rats were divided into 3 groups. In the first group, a strip of mucoperiosteum was excised on both sides of the hard palate. A second group of rats received a sham surgery in which bilateral mucoperiosteal flaps were raised and redraped. The third group served as controls with no surgery. Flap elevation with and without excision was performed under an operative microscope to facilitate the delicate manipulation of tissue and to avoid injury to the underlying bone. The animals were killed 11 weeks later and the skulls were prepared for measurements, which included the palatal inter-molar width, maxillary height, and maxillary length. RESULTS: The results revealed statistically significant decreases in palatal width and maxillary length in the experimental group (excision of mucoperiosteum). No differences were observed in the vertical height of the maxilla. CONCLUSION: This study confirms that surgically created bone denudation of the palate causes maxillary growth disturbances.

Animals↗

PubMed1999

The role of multiple segment osteotomies in orthognathic surgery.

Multiple segment orthognathic (MSO) surgery is an effective approach to deal with a wide range of dento-facial deformities that have occlusal problems. The indications for MSO surgery were patients with dentofacial deformities and malocclusion requiring stable correction within a short overall treatment period. From 1991 to 1998, 107 patients had MSO orthognathic procedures done at Chang Gung Memorial Hospital for maxillary protrusion/deformity (34 cases), maxillary protrusion and mandibular prognathism (69 cases), and non-cleft maxillary retrusion (4 cases). Follow up period ranged from 6 months to 7 years and results showed stability in movements with only 3 complications. The average overall treatment time was approximately 15 months. Our experience with 107 consecutive patients have shown the results of MSO surgery to be good and the procedure safe with no tooth or segment loss.

Adolescent↗

PubMed1999

A comparative study of various fixation methods for mandibular fracture.

BACKGROUND: Internal rigid fixation for mandibular fractures has been recognized as a reliable method for obtaining osteosynthesis. It may allow for early active physiotherapy and resumption of normal function. However, few studies have compared the various fixation methods. METHODS: From January 1993 through December 1997, 101 patients with mandibular fractures, who were selected for study, received treatment using various fixation methods at the Craniofacial Center, Chang Gung Memorial Hospital. The fixation methods included plate fixation in 44 patients, lag screw fixation in 30, combined plate and lag screw fixation in 15, and wire fixation in 12. Clinical data assessment was performed by reviewing hospital records. For assessment of the long-term surgical results, the patients were asked to complete a questionnaire including questions which specifically targeted history regarding occlusion, mastication, facial asymmetry, width of mouth opening, and general appearance. RESULTS: The outcome assessment showed statistically different results among the groups. The wire group required intermaxillary fixation more often and for a longer duration compared to the groups using plates and/or lag screws. The plate, lag screw, and combined plate and lag screw fixation groups had better total outcome scores, in particular for long-term dental occlusion and mastication function. CONCLUSION: This study shows that for mandible fractures, the more rigid types of fixation methods, i.e., plates and screws or lag screws, can offer better short and long-term outcomes.

Adolescent↗

PubMed1998

Inhibition of the c-Jun N-terminal kinase (JNK) signaling pathway by curcumin.

Curcumin, a dietary pigment in curry, suppresses tumor initiation and tumor promotion. Curcumin is also a potent inhibitor for AP-1 and NF-kappaB activation. In this report, we show that curcumin inhibits JNK activation by various agonists including PMA plus ionomycin, anisomycin, UV-C, gamma radiation, TNF-alpha, and sodium orthovanadate. Although both JNK and ERK activation by phorbol 12-myristate 13-acetate (PMA) plus ionomycin were suppressed by curcumin, the JNK pathway was more sensitive. The IC50 (50% inhibition concentration) of curcumin was between 5-10 microM for JNK activation and was 20 microM for ERK activation. In transfection assays, curcumin moderately suppressed MEKK1-induced JNK activation; however, it effectively blocked JNK activation caused by co-transfection of TAK1, GCK, or HPK1. Curcumin did not directly inhibit JNK, SEK1, MEKK1 or HPK1 activity. Although curcumin suppressed TAK1 and GCK activities at high concentrations, this inhibition cannot fully account for the JNK inhibition by curcumin in vivo. Our data suggest that curcumin may affect the JNK pathway by interfering with the signaling molecule(s) at the same level or proximally upstream of the MAPKKK level. Taken together, the inhibition of the MEKK1-JNK pathway reveals a possible mechanism of suppression of AP-1 and NF-kappaB signaling by curcumin, and may explain the potent anti-inflammatory and anti-carcinogenic effects of this chemical.

Antineoplastic Agents↗

PubMed1998

Effects of acute intravenous cocaine on cardiovascular function, human learning, and performance in cocaine addicts.

Continuous non-invasive cardiovascular monitoring in eight healthy cocaine addicts receiving intravenous cocaine (0.325 mg/kg or 0.650 mg/kg) or placebo in double-blind, randomized, cross-over fashion demonstrated significant dose-dependent increases in pulse and mean arterial pressure following cocaine. Pulse and mean arterial pressure peaked 5 min post-cocaine injection and maximal response was sustained for a further 15 min and 35 min afterwards, respectively. Cocaine administration had no significant effect on peripheral oxygen saturation, and no clinically significant abnormalities of rhythm or conduction were seen on the electrocardiogram. These doses and method of single-dose intravenous cocaine administration, and our procedures for cardiovascular monitoring, appear relatively safe for laboratory studies of healthy cocaine addicts with no pre-existing cardiovascular disease. In addition, cocaine-taking (0.325 mg/kg i.v. and 0.650 mg/kg i.v.) was associated with enhanced attention (i.e. increased numbers of correct responses on the Rapid Visual Information Processing Task), but the trend towards reduced reaction time did not achieve statistical significance. Cocaine-taking resulted in a small but statistically insignificant improvement in learning on the Digit Symbol Substitution Task. These results suggest that cocaine-taking in rested subjects is associated with some cognitive enhancement.

Adult↗

PubMed1998

Molecular mechanisms of c-Jun N-terminal kinase-mediated apoptosis induced by anticarcinogenic isothiocyanates.

Isothiocyanates have strong chemopreventive properties against many carcinogen-induced cancers in experimental animal models. Here, we report that phenylmethyl isocyacyanate (PMITC) and phenylethyl isothiocyanate (PEITC) induced sustained c-Jun N-terminal kinase (JNK) activation in a dose-dependent manner. The sustained JNK activation caused by isothiocyanates was associated with apoptosis induction in various cell types. An inhibitor of the caspase/interleukin-1 beta-converting enzyme blocked isothiocyanate-induced apoptosis without inhibiting the JNK activation, which suggests that JNK activation by isothiocyanates is an event that is independent or upstream of the activation of caspase/interleukin-1 beta-converting enzyme proteases. PEITC-induced apoptosis was suppressed by interfering with the JNK pathway with a dominant-negative mutant of JNK1 or MEKK1 (JNK1(APF) and MEKK1 (KR), respectively), implying that the JNK pathway is required for apoptotic signaling. Isothiocyanate-induced JNK activation was blocked by the antioxidants 2-mercaptoethanol and N-acetyl-L-cysteine, suggesting that the death signaling was triggered by oxidative stress. Overexpression of Bcl-2 suppressed PEITC-induced JNK activation. In addition, Bcl-2 and Bcl-xL suppressed PEITC-induced apoptosis, but failed to protect cells from death induced by overexpression of activated JNK1. These results suggest that Bcl-2 and Bcl-xL are upstream of JNK. Taken together, our results indicate (i) that JNK mediates PMITC- and PEITC-induced apoptosis and (ii) that PMITC and PEITC may have chemotherapeutic functions besides their chemopreventive functions.

Aldehyde Dehydrogenase↗

PubMed1998

Validity of using fixation screws/wires as alternative landmarks for cephalometric evaluation after LeFort I osteotomy.

The most widely used method to measure postoperative stability of a surgically repositioned bony segment is based on skeletal landmarks. Unfortunately, orthognathic surgery may alter the skeletal landmarks and bony configurations that are commonly used for cephalometric analysis. Intraosseous wires, plates, and screws are routinely used in orthognathic surgery, and postoperatively they are easier to identify than skeletal landmarks. Cephalometric radiographs from 25 adult patients, who had undergone LeFort I one piece osteotomy, were used to analyze the validity of fixation wires/screws used as landmarks to evaluate postoperative stability of the maxilla. The positional changes of maxillary skeletal landmarks (A point and anterior and posterior nasal spines) and intraosseous fixation wires/screws were measured relative to the cranial base. The fixation screws/wires were also measured relative to the invariant maxillary trabecular patterns and palatal plane from 1 to 6 weeks (T1-T2) and 6 weeks to 1 year postoperatively. The reproducibility of fixation wires/screws was found to be higher than that of skeletal landmarks. The fixation wires/screws remained stable in the maxilla; their postoperative positional changes were not significantly different from those of the skeletal landmarks. When the skeletal landmarks are altered or no longer exist after LeFort I osteotomy, fixation wires/screws could be used as alternative landmarks to measure the maxillary postoperative stability.

Adult↗

PubMed1998

The "Taiwanese giant": hormonal and genetic influences in fibrous dysplasia.

A 14-year-old boy has been followed for 4 years with a rapidly growing, recurrent area of fibrous dysplasia of the left maxilla and zygoma following resection and bone grafting. Standing 190 cm tall, he was found to have elevated serum growth hormone levels and a pituitary adenoma. His case appears to represent a postzygotic gene mutation of McCune-Albright syndrome. It is possible that the elevated growth hormone levels are in part responsible for the rapid progression of the tumor.

Adolescent↗

PubMed1998

Transzygomatic coronoidectomy through an extended coronal incision for treatment of trismus due to an osteochondroma of the coronoid process of the mandible.

Osteochondroma is the most common benign tumor of the skeletal system. In the craniofacial skeleton, however, osteochondroma is uncommon. Even more rare is osteochondroma of the coronoid process. A review of the literature reveals only 31 reported cases of osteochondroma of the coronoid process of the mandible. The preponderance of patients were young men (67.7%) and most presented with a facial deformity. As a benign tumor, the problems with surgical treatment have dealt with the inaccessibility of the lesion and hence the surgical approach of choice. The previous surgical approaches have either been intraoral, external, or a combination of both. We present a transzygomatic approach via a coronal incision that gives excellent access and a good cosmetic result, and protects the facial nerve from damage.

Bone Plates↗

PubMed1998

Silicone molar block used as a fulcrum in condylar surgery.

The narrowness of the temporomandibular joint (TMJ) can cause difficulty in open reduction and fixation of condylar fracture. The authors designed a silicone block that acts as a fulcrum to create more space around the TMJ. The block is made of high-quality silicone that is firm, elastic, nontoxic, autoclave tolerant, and harmless to dental tissue. This block has been used successfully in facilitating reduction and fixation of condylar fractures in 27 patients, and for releasing spastic muscles during closed reduction in 2 patients with prolonged TMJ dislocation. In edentulous patients, the silicone molar block can be used as a mouth opener to facilitate most intraoral procedures without injury to the gum.

Adult↗