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Biomedical subjects

Y R Chen

Publications and source records attributed to Y R Chen.

At least 109 records · Page 6Linked to original sources
PubMed1997

Maxillary myxoma treated with wide resection and immediate reconstruction: a case report.

Myxoma of the jaw is a rare, benign bone tumor of odontogenic origin. Given the locally aggressive nature of the myxoma and the high rate of recurrence, there is a tendency to choose radical resection of the jaw segment containing the tumor mass as the treatment modality. As they appear to attain a considerable size prior to diagnosis because of their insidious growth characteristics, particularly in the maxilla, treatment requiring a hemimaxillectomy often results in a significant functional and aesthetic disability. This is particularly distressing as this condition usually affects the young. We present the case of a 16-year-old female who suffered a large maxillary myxoma with swelling of the left cheek for 2 years. Wide resection of the tumor tissue including the maxillary medial and lateral buttresses and part of the hard palate with preservation of maxillary alveolar bone and teeth was undertaken, and the maxillary buttresses were reconstructed with autogenous rib grafts. At the 3.5-year follow-up there was no local recurrence and no tooth loss. Both the functional result and aesthetic contour proved satisfactory. Wide resection with preservation of vital structures and simultaneous autogenous bone graft reconstruction is our preferred method. A long-term follow-up is needed.

Adolescent↗
PubMed1997

Malignant fibrous histiocytoma degeneration in a patient with facial fibrous dysplasia.

Seventy-two patients with craniofacial fibrous dysplasia were treated during a period of 18 years. Only 1 patient (1.4%) developed malignant degeneration into malignant fibrous histiocytoma. Total excision including the gross mass and adjacent facial bone was performed at that time, however the patient refused an orbital exenteration and postoperative adjuvant therapy. Tumor recurrence developed 2 years later and the patient died. To our knowledge this is the first report describing malignant fibrous histiocytoma degeneration from a fibrous dysplasia localized to the facial bones. Although complete curative treatment could not be undertaken in this case, some conclusions can be drawn regarding the clinical course of this uncommon entity.

Adult↗
PubMed1997

Full intrusion of a tooth after facial trauma.

We report two cases of fully intruded tooth after facial fracture in adults. In the first case, the lateral incisor was intruded into the nasal cavity and slipped into the pyriform sinus during operation. The second case involved full intrusion of a molar into the maxillary sinus, resulting in infection. The importance of a thorough intraoral examination for patients with facial trauma is emphasized. All missing teeth should be accounted for to ensure that they have not dislodged inside the body. When full intrusion of a tooth is suspected, facial computed tomography scan may provide assistance with definite diagnosis. If an incisor is completely intruded into the nasal cavity, removal through the floor of the nostril should be considered.

Accidents, Traffic↗
PubMed1997

Optic nerve decompression in fibrous dysplasia: indications, efficacy, and safety.

Optic nerve decompression is controversial in posttraumatic visual loss and as a prophylactic therapy in fibrous dysplasia involving the optic canal. It is less controversial for the treatment of optic nerve compression in fibrous dysplasia. Thirteen patients with craniomaxillofacial fibrous dysplasia who underwent 16 optic nerve decompressions at the Chang Gung Craniofacial Centre for both therapeutic (10) and prophylactic (6) indications are reported. One patient sustained a clinically useful improvement in vision in response to two therapeutic decompressions, and another demonstrated marked improvement after therapeutic decompression, with visual acuity improving from 0.4 to 1.0 in the affected eye. No patient underwent a permanent deterioration of vision as a result of either therapeutic or prophylactic decompression. One patient suffered extraocular muscle dysfunction that was corrected with strabismus surgery. A review of the literature clarifies the controversies and allows establishment of indications for optic nerve decompression.

Adolescent↗
PubMed1997

Refined frontalis fascial sling with proper lid crease formation for blepharoptosis.

Ptosis of the upper eyelid is a complicated problem, and many surgical techniques have been developed for the treatment of ptosis. Frontalis sling with autogenous fascial strip for the correction of severe ptosis with poor levator function is still well accepted. The treatment necessitates an understanding of the etiology of ptosis, detailed history taking, degree of ptosis, the levator function, the anatomic basis of the ptosis and lid crease, and a historic review of surgical procedures. The refinement of our procedure consists of a circular type of frontalis sling with an autogenous fascial strip, harvested from fasciae latae or temporalis fascia, with evenly balanced strength and partial lid resection, including a semilunar segment of skin flap and orbicularis muscle and moderate amount of protruded orbital fat from the orbital septum. The fascial strip is anchored simultaneously to the upper margin of the tarsal plate and incision margin of the pretarsal lid to produce a proper lid crease. This procedure has been successful in the management of 64 lids (46 patients) with a severe degree of ptosis and poor levator function. Satisfactory results have been achieved in 57 lids (89 percent) according to the modified criteria of Berke after an average follow-up period of 18.5 months. Most patients (87.5 percent) have mild lid lag (1 to 3 mm) after the operation, but 58 lids (90.6 percent) achieved a proper lid crease height of 3 to 6 mm.

Adolescent↗
PubMed1997

Tretinoin or retinol enhancement of lymphokine-activated killer cell proliferation and cytotoxicity against human bladder cancer cells in vitro.

AIM: To study the effect of tretinoin (Tre) or retinol (Ret) on the proliferation of lymphokine-activated killer (LAK) cells in patients with transitional cell cancer of bladder and their cytolysis to bladder tumor cells. METHODS: LAK cell proliferation was assayed in the presence of either Tre or Ret by cell counting. Human transitional bladder cancer cell lines BIU-87, EJ, or bladder tumor cells (BTC) from patients with bladder cancer were used as target cells and cytotoxicity of LAK cells was determined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. RESULTS: The proliferation of LAK cells induced by interleukin-2 (IL-2) was stimulated by Tre or Ret (10-100 nmol.L-1). The cytotoxicity of LAK cells against BIU-87, EJ cells, or BTC was enhanced by pretreatment of LAK cells with Tre or Ret 10-100 nmol.L-1. CONCLUSION: Tre or Ret enhances the proliferation and cytotoxicity of LAK cells from patients with bladder cancer. Retinoids are potential in adoptive immunotherapy of bladder cancer.

Antineoplastic Agents↗
PubMed1997

Ethnocultural differences in prevalence of adolescent suicidal behaviors.

Data from an ethnically diverse sample of middle school students (grades 6-8; n = 5,423) are analyzed for ethnic differences in suicidal ideation, thoughts about suicide in the past 2 weeks, suicide plans, and suicide attempts. Ideation was examined using a four-item scale and a single item on suicidal thoughts. Ideation was higher among females, older youths, and lower status youths. The same general pattern held for recent suicidal plans and attempts, with the exception of gender, where the trend was for males to report more attempts. Lifetime plans and attempts were higher for females, older youths, and lower status youths. Data were sufficient to compare nine ethnic groups. Multivariate logistic regression analyses, adjusting for the effects of age, gender, and socioeconomic status, yielded significant odds ratios using the Anglo groups as the reference, for suicidal ideation for the Mexican (OR = 1.76, p < .001), Pakistani (OR = 2.0, p < .01), and Vietnamese (OR = 1.48, p < .05) American groups. For thoughts about suicide in the past 2 weeks, only Pakistani and Mixed Ancestry youths had elevated risk. For suicidal plans in the past 2 weeks, Mixed Ancestry youths (OR = 2.02, p < .05) and Pakistani youths (OR = 3.20, p < .01) had elevated risk. For recent attempts, only the Pakistani American youths had elevated risk (OR = 3.19, p < .01). Future research needs to address whether these results hold in other ethnically diverse communities and, if so, what factors contribute to increased risk among some minority youth and not others.

Adolescent↗
PubMed1997

Infantile myofibromatosis: a solitary lesion involving the upper lip.

Infantile myofibromatosis is a rare disease characterized by myofibroblastic proliferation, and typically occurs in early infancy. There is a wide spectrum of clinical presentation, which may involve various kinds of tissues in the body. Skin and subcutaneous lesions were the types of tissue most often seen. Although a multicentric form may behave aggressively, a solitary form of the tumor is benign with the possibility of spontaneous regression. Conservative management is justified after proper pathological diagnosis if the tumor involves an aesthetically important area. A case of solitary infantile myofibromatosis involving the upper lip is presented. Partial excision for biopsy was performed and long-term observation was undertaken. The tumor disappeared 3 years postoperatively.

Actins↗
PubMed1996

The role of c-Jun N-terminal kinase (JNK) in apoptosis induced by ultraviolet C and gamma radiation. Duration of JNK activation may determine cell death and proliferation.

c-Jun N-terminal kinases (JNKs) participate in cellular responses to mitogenic stimuli, environmental stresses, and apoptotic agents. The mechanisms by which JNK integrates with other signaling pathways and regulates the diverse cellular events are unclear. We found JNK, but not p38-mitogen-activated protein kinase (MAPK) or extracellular signal-regulated kinase 2, to be persistently activated in apoptosis induced by gamma radiation, UV-C, and anti-Fas treatment. Direct correlation was found between JNK activation and apoptosis induced by UV-C and gamma radiation; however, JNK induction and apoptosis induced by Fas signaling were not well correlated. Overexpression of activated JNK1 caused cell death in transfected cells, and the expression of a dominant-negative mutant of MAPK kinase 1 or JNK1 (but not a dominant-negative mutant of p38-MAPK or c-Raf) prevented the UV-C- and gamma radiation-induced cell death. The inductions of JNK in T-cell activation and apoptosis were distinguished by the different activation patterns, transient versus persistent, respectively. Co-treatment with a tyrosine phosphatase inhibitor (sodium orthovanadate) and T-cell activation signals (phorbol 12-myristate 13-acetate plus ionomycin) prolonged JNK induction, followed by T-cell apoptosis. Our data revealed the requirement of the JNK pathway in radiation-induced apoptosis and implicated the importance of the duration of JNK activation in determining the cell fates.

Apoptosis↗
PubMed1996

Functional expression of subunit IV of Rhodobacter sphaeroides cytochrome b-c1 complex and reconstitution of recombinant protein with three-subunit core complex.

Subunit IV of Rhodobacter sphaeroides cytochrome b-c1 complex was over-expressed in Escherichia coli JM109 cells as a glutathione S-transferase fusion protein (GST-RSIV) using the expression vector, pGEX/RSIV. Maximum yield of soluble active recombinant fusion protein was obtained from cells harvested 3 h after induction of growth at 37 degrees C in LB medium. Subunit IV was released from the fusion protein by proteolytic cleavage with thrombin. When subjected to SDS-polyacrylamide gel electrophoresis, isolated recombinant subunit IV of R. sphaeroides cytochrome b-c1 complex. Although the isolated recombinant subunit IV is soluble in aqueous solution, it is in a highly aggregated form, with an apparent molecular mass of over 1000 kDa. The addition of detergent deaggregates the isolated protein, suggesting that the recombinant protein exists as a hydrophobic aggregation in aqueous solution. When the three-subunit core cytochrome b-c1 complex, purified from RS delta IV-adapted chromatophores containing a fraction of the wild type cytochrome b-c1 complex activity, was reacted with varying amounts of recombinant subunit IV, the activity increased as the subunit IV concentration increased. Maximum activity restoration was reached when 1 mol of subunit IV/mol of three-subunit core complex was used. The reconstituted cytochrome b-c1 complex is similar to the wild-type complex in molecular size, apparent Km for Q2H2, and inhibitor sensitivity, indicating that recombinant subunit IV is properly assembled into the active cytochrome b-c1 complex. A tryptophan residue in subunit IV was found to be involved in the interaction with the three-subunit core complex.

Base Sequence↗
PubMed1996

Persistent activation of c-Jun N-terminal kinase 1 (JNK1) in gamma radiation-induced apoptosis.

The c-Jun N-terminal kinases (JNK) are activated by various stimuli, including UV light, interleukin-1, tumor necrosis factor-alpha (TNF-alpha), and CD28 costimulation. Induction of JNK by TNF-alpha, a strong apoptosis inducer, implies a possible role of JNK in the regulation of programmed cell death. Present studies show that lethal doses of gamma radiation (GR) induced JNK activities at the early phase of apoptosis in Jurkat T-cells. We demonstrate that JNK1 was activated by either the T-cell activation signals, anti-CD28 monoclonal antibody plus phorbol 12-myristate 13-acetate (PMA), or the apoptosis-inducing treatment, GR; however, the induction patterns were different. In contrast to the rapid and transient JNK1 activation caused by CD28 signaling plus PMA, GR induced a delayed and persistent JNK1 activation. This implies a distinct regulatory mechanism and specific function of JNK1 in irradiated cells. The nuclear and cytosolic JNK1 activities were simultaneously increased in the irradiated cells without an evident change in the protein levels. The abilities of GR to induce JNK1 activation and DNA fragmentation were correlated. Peripheral blood lymphocytes were more sensitive to GR than Jurkat cells in JNK1 induction. The responsiveness of JNK1 to GR suggests the involvement of JNK1 in the initiation of the apoptosis process.

Apoptosis↗
PubMed1996

The moderating roles of self-esteem and self-construal in reaction to a threat to the self: evidence from the People's Republic of China and the United States.

The present research evaluated whether a well-established finding in the U.S.-based self-esteem literature (i.e., a positive relationship between trait self-esteem and self-protection following a threat to the self) was moderated by individuals' self-construal. Participants varying in self-esteem and degree of independent self-construal were studied in 2 different cultures: the United States and the People's Republic of China. Half of the participants received negative individual performance feedback, whereas the remaining half did not. For the U.S. sample (but not the People's Republic of China sample) as a whole, the authors observed a positive relationship between trait self-esteem and self-protection in response to negative feedback. However, the subset of participants from the People's Republic of China with more independent self-construals did exhibit a positive relationship between trait self-esteem and self-protection in response to negative feedback.

Adaptation, Psychological↗
PubMed1996

Extended open-tip rhinoplasty with three V-flaps for secondary correction of bilateral cleft lip nasal deformity.

Many procedures have been developed to correct the secondary cleft lip nasal deformity, including the depressed nasal tip, flaring nasal aperture, and a very short columella. The forked flap, cartilage graft, or strut and bony graft have been applied for many years. We propose the extended open-tip rhinoplasty with three V-flaps, which we have performed on 12 patients during the past 3 years. An extended incision for the nasal skin flap exposes all deformities to direct vision, makes the advancement and rotation of the nasal skin flap complete, and makes the corrective procedures easy and accurate. A large V-flap (with V-Y advancement for columellar lengthening) and two small V-flaps (with back-cut incisions on the nasal lining) are used to elevate and suspend the alar domes and cartilage to create two symmetrical and piriform apertures, and to ensure adequate columellar length. Columellar lengthening averaged from 2.5 mm preoperatively to 10 mm postoperatively. A protruded nasal tip with two delicate and small dimples over the alar rims, and a piriform aperture of the nasal nares were achieved in our series. No hypertrophic scar, nasal obstruction, or exposure of hairy nares were noted. No cartilage graft or strut and bone graft were required.

Adolescent↗
PubMed1996

Hemimandibular hyperplasia.

True hemimandibular hyperplasia is an uncommon maxillofacial deformity. Patients with this affliction present clinically with varying degrees of asymmetry characterized by an increase in ramus height, a rotated facial appearance with kinking at the mandibular symphysis, and prominence of the lower border of the mandible. In the advanced form, maxillary and mandibular alveolar bone overgrowth result in a compensatory canting of the occlusal plane and a significant functional malocclusion requiring bimaxillary surgical correction. Nine patients with the above condition were treated with various surgical methods over a 9-year period. The clinical results were satisfying and the long-term results showed good postoperative stability. The pathology of hemimandibular hyperplasia is described and the preexisting nomenclature further defined.

Adolescent↗
PubMed1996

Surgical correction of submucous cleft palate with Furlow palatoplasty.

Many surgeons have favored using the pharyngeal flap as the primary treatment for the velopharyngeal insufficiency associated with submucous cleft palate. However, the increasing number of reports of sleep apnea and airway compromise as a result pharyngeal flap surgery support the need to eliminate any unnecessary pharyngeal flap surgery. From 1988 to 1993, 35 Chinese submucous cleft palate patients with velopharyngeal insufficiency received surgery. A Furlow palatoplasty was used in 30 patients (3 to 26 years old). The follow-up duration was 9 months to 5 1/2 years. These patients were selected after a thorough study for velopharyngeal insufficiency including intraoral examination, perceptual speech assessment, videonasopharyngoscopy, and/or multiview videofluoroscopy. The criteria for selection included age, intraoral finding of an obviously anterior inserted levator palatine muscle, size of velopharyngeal gap, pattern of velopharyngeal closure, degree of lateral pharyngeal wall movement, and response to biofeedback speech therapy. In general, younger patients with circular or sagittal pattern closure, a velopharyngeal gap less than 5 mm, or good response to biofeedback speech therapy were considered to be the best candidates for a Furlow palatoplasty. The 5 patients who did not fulfill these criteria and whose velopharyngeal function failed to improve on preoperative biofeedback therapy were treated by pharyngeal flap operation. Twenty-nine patients (96.7 percent) achieved competent velopharyngeal function after the Furlow palatoplasty. The procedure corrected the velopharyngeal insufficiency in 3 patients older than 20 years with a velopharyngeal gap of less than 2 mm. The only patient with an unsatisfactory result was a 26-year old woman who had very prominent action of the musculus uvulae before the surgery. The results show that a Furlow palatoplasty can satisfactorily correct velopharyngeal insufficiency in carefully selected submucous cleft palate patients and thus avoid the serious complications of pharyngeal flap surgery.

Adolescent↗
PubMed1996

Stability of diagnosis in schizophrenia.

OBJECTIVE: The authors investigated factors associated with change in diagnosis from schizophrenia to other disorders and from other disorders to schizophrenia, as well as the time elapsed before diagnostic change. METHODS: Using a longitudinal study design, they examined data collected over a 7-year period at an urban acute care psychiatric hospital. The subjects were 936 inpatients who had been hospitalized at least four times during the study period. Changes to and from a diagnosis of schizophrenia over the 7 years were investigated in relation to demographic variables, socioeconomic factors, and clinical features. RESULTS: Fifty-six (21.9%) of the 256 subjects with a diagnosis of schizophrenia at the beginning of the study received a different diagnosis during a subsequent hospitalization. Females and subjects of Hispanic origin were more likely to undergo a diagnostic change from schizophrenia. Two hundred twenty-three (32.8%) of the 680 subjects who initially had a diagnosis other than schizophrenia were later diagnosed with schizophrenia. Males and African Americans had significantly higher rates of change to a diagnosis of schizophrenia than females and other ethnic groups. In addition, socio-economic factors and clinical features were associated with a change in diagnosis from another disorder to schizophrenia. CONCLUSIONS: The diagnosis of schizophrenia, in current practice, is not static. Patients' characteristics interact with longitudinal clinical changes to produce shifts in diagnosis. Longitudinal follow-up is necessary to validate diagnoses.

Adult↗
PubMed1996

Effects of GR 68755 on d-amphetamine-induced changes in mood, cognitive performance, appetite, food preference, and caloric and macronutrient intake in humans.

Pre-clinical studies have suggested that 5-HT(3) antagonists such as GR 68755 oppose mesocorticolimbic dopamine release, which may mediate the important effects of d-amphetamine on positive subjective mood, anorexia, and performance. Twenty-six healthy male volunteers received each of the following treatments in a double-blind, randomized, cross-over design separated by a period of four to seven days: (a) d-amphetamine (20mg orally); (b) placebo; (c) GR 68755 (2mg orally); and (d) GR 68755 plus d-amphetamine. Subjects completed subjective measures of mood, hunger, and satiety. Caloric and macronutrient intake were measured using a test meal. Performance and attention were assessed using standardized computerized tasks. GR 68755 enhanced accuracy on the computerized attention task but failed to reverse significantly any of the effects of d-amphetamine. These results suggest that at these doses GR 68755 pre-treatment does not significantly reduce the effects of d-amphetamine.

Journal Article↗