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Biomedical subjects

Y R Chen

Publications and source records attributed to Y R Chen.

At least 145 records · Page 8Linked to original sources
PubMed1994

Ecology and control of dengue vector mosquitoes in Taiwan.

Due to rapid urbanization, industrialization and social changes in recent years, the use of packing materials and tires has dramatically increased in the Taiwan area. What is more is that some parts of southern Taiwan are short of water resources and water preservation with huge containers becomes part of custom in those areas. Storage water containers, waste vessels and tires are good habitats for Aedes. Meanwhile, some persons traveling to dengue endemic countries bring the dengue disease back to Taiwan. Surveys taken since 1988 show that dengue occurs mainly in the urban and coastal areas where Aedes aegypti is prevalent. This species is the most important, if not the only, vector of dengue in Taiwan. It appears that the types of Aedes breeding have changed quickly. In dengue fever epidemic areas, the most popular breeding sites are ornamental containers (38.8%), storage water containers (30.1%), discarded containers (25.4%), receptacles (3.3%) and water collection in the basement (2.2%). In dengue fever epidemic areas, those building basements, huge water containers, waste vessels and waste tires in open fields are most difficult to clean up and manage and become the most popular Aedes habitats. We established a waste recycling system and promoted a breeding site reduction campaign for waste management, including the application of Temephos in containers to kill larvae. For the drinking water management, fish were released in water containers to prevent larval breeding. It should be mentioned that with the integrated pest control and regular inspections of Aedes larvae in Taiwan the density figures 1, 2-5, and 6 or above for Aedes aegypti were 38.7%, 42.9%, and 18.4%, respectively, in 1988, and in 1993 were 90.8%, 9.2% and 0%. The incidence of dengue fever cases has 98% decreased since 1988. In 1990 and 1993, there was no indigenous cases. We have concluded that integrated pest control is the best and most effective method for dengue fever control, including solid waste and drinking water management.

Aedes↗
PubMed1994

A case report of triple nostrils.

A rare case of supernumerary nostril is reported. The surplus nostril was located above and lateral to the right normal nostril and ended blindly. Fistulorhinoplasty was performed and the result was good.

Humans↗
PubMed1994

Correction of secondary velopharyngeal insufficiency in cleft palate patients with the Furlow palatoplasty.

To avoid the serious complications of pharyngeal flap surgery, a Furlow palatoplasty was used to correct velopharyngeal insufficiency after primary palatoplasty in 18 Chinese cleft palate patients (3 to 23 years old) from 1988 to 1992. The follow-up duration was 1 to 4 years. These patients were selected after a complete study for velopharyngeal insufficiency, including intraoral examination, perceptual speech assessment, videonasopharyngoscopy, and/or multiview videofluoroscopy. The criteria for selection included age, pattern of velopharyngeal closure, size of the velopharyngeal gap, extent of lateral pharyngeal wall movement, existence of a Passavant's ridge, and abnormal levator veli palatini muscle insertion. Complete velopharyngeal closure was achieved for 16 patients after surgery. The majority of these patients (15) had a velopharyngeal gap less than 5 mm. The 2 patients who still had velopharyngeal insufficiency after the surgery had a velopharyngeal gap larger than 10 mm before the surgery. The most important factor seemed to be the size of the velopharyngeal gap. Pattern of velopharyngeal closure or age of the patient also might play an important role. The results showed that a Furlow palatoplasty can satisfactorily correct velopharyngeal insufficiency in carefully selected patients. Although the criteria for the selection of this operation need further study, present results are encouraging.

Adolescent↗
PubMed1993

Perturbation of reaction-intermediate partitioning by a site-directed mutant of ribulose-bisphosphate carboxylase/oxygenase.

To explore the roles of active-site Glu48 of ribulose-bisphosphate carboxylase/oxygenase from Rhodospirillum rubrum, the E48Q mutant has been characterized with respect to kinetics and product distribution. Although the kcat for carboxylase activity is only 0.6% of the wild-type value, the mutant retains full activity in catalyzing the conversion of the carboxylated reaction intermediate to 3-phosphoglycerate and retains 10% of the normal activity in catalyzing the enolization of ribulose bisphosphate. Thus, the mutant is preferentially impaired in the carboxylation step. Partitioning of the enediol(ate) intermediate during turnover of ribulose bisphosphate is perturbed dramatically in the case of the mutant protein. Whereas the wild-type enzyme displays a CO2/O2 specificity factor of 11, the corresponding parameter of the mutant is only 0.3, thereby signifying a shift of the relative reactivity of the enediol(ate) in favor of O2. The mutant protein is also unable to protect the enediol(ate) against misprotonation with consequential conversion of ribulose bisphosphate to xylulose bisphosphate. This side reaction, undetected with wild-type R. rubrum enzyme, proceeds as rapidly as carboxylation of D-ribulose 1,5-bisphosphate by the E48Q mutant. Formation of xylulose bisphosphate by the mutant does not appear to account for the decline in carboxylase activity that occurs during the course of an assay. These studies demonstrate the multiple functionalities of Glu48 in the facilitation of catalysis and in directing intermediate partitioning in the preferred direction.

Binding Sites↗
PubMed1993

Structural characterization of isolated mitochondrial cytochrome c1.

Resonance Raman spectroscopy (RRS) has been employed to characterize cytochromes c1 isolated from bc1 complexes of beef heart mitochondria and Rhodopseudomonas sphaeroides. The data obtained in this study extend the physical characterization of cytochromes c1 and focus on the effects of the local protein environment on the heme active site. While the general characteristics of the cytochromes c1 are similar to those of smaller soluble cytochromes c, the behavior of several core-size and ligation-sensitive heme modes reveal that significant systematic differences exist between those species. These, most likely, result from changes in the heme axial-ligand interactions.

Animals↗
PubMed1993

A role for the epsilon-amino group of lysine-334 of ribulose-1,5-bisphosphate carboxylase in the addition of carbon dioxide to the 2,3-enediol(ate) of ribulose 1,5-bisphosphate.

Earlier structural and functional studies of ribulose-1,5-bisphosphate carboxylase/oxygenase imply that K334 facilitates the addition of gaseous substrate to the 2,3-enediol(ate) derived from ribulose 1,5-bisphosphate. Crystallographic analysis of the activated spinach enzyme [Knight et al. (1990) J. Mol. Biol. 215, 113-160] shows that the lysyl side chain is appropriately positioned to stabilize the transition state for the addition of CO2 to the enediol(ate). Furthermore, despite total impairment of carboxylase and oxygenase activities, site-directed mutants of the Rhodospirillum rubrum enzyme with replacements for lysine K334 (formerly designated K329) retain the capacity to enolize ribulose bisphosphate, demonstrating that the primary catalytic lesion lies beyond this initial step [Soper et al. (1988) Protein Eng. 2, 39-44; Hartman & Lee (1989) J. Biol. Chem. 264, 11784-11789]. We now show that the K334C mutant is also competent in the latter stages of catalysis, whereby 2'-carboxy-3-keto-D-arabinitol 1,5-bisphosphate, the six-carbon intermediate of the carboxylation pathway, is correctly processed to 3-phosphoglycerate. Thus, the impairment of the mutant in overall catalysis can be attributed to preferential disruption of the reaction of CO2 or O2 with the enzyme-bound enediol(ate). Chemical rescue of the K334C mutant by aminoethylation and aminopropylation shows that this disruption reflects, at least in part, a failure to adequately stabilize the relevant transition state. With several simplifying assumptions, the CO2/O2 specificity factor tau can be reduced to the ratio of the fundamental second-order rate constants for the interaction of the gaseous substrates with the enzyme-bound 2,3-enediol(ate) of ribulose bisphosphate.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗
PubMed1993

Use of split anterior tibial muscle flap in treating avulsion injury of leg associated with tibia exposure.

Avulsion injury of the leg may result in exposure of the anterior surface of the tibia in addition to skin loss. This exposed bone should be covered by a soft tissue flap to facilitate healing and provide durability. The split anterior tibial muscle flap is ideal in this situation because of its adjacent location, reliability, and simplicity. A cadaveric study demonstrated rich intramuscle vascular anastomoses between the segmental branches from the anterior tibial artery that provide safety in partial transfer. The technique of split anterior tibial muscle flap was applied successfully in 4 patients with leg avulsion injury associated with tibial bone exposure. The cosmetic result was good and the function of the muscle was preserved.

Adult↗
PubMed1993

Orbitozygomatic infratemporal approach to lateral skull base tumors.

An orbitozygomatic infratemporal approach for the removal of large neoplasms involving the lateral skull base is described. This approach, involves a unilateral frontotemporal incision extended inferiorly to the neck, a lateral facial flap reflected anteriorly. Transection of the zygoma is followed by its reflection inferolaterally with the temporalis muscle. This exposure provides excellent visualization of both the intradural and extradural aspects of the anterior portion of the cavernous sinus, allowing an aggressive resection of neoplasms in this region. Experience with this procedure in the management of 15 patients is reported here. There was one postoperative death due to pneumonia and septicemia. The morbidities included wound infection, meningitis, CSF leakage and cranial nerve palsy. All the surviving patients, are living independently and have returned to their previous occupations.

Adolescent↗
PubMed1993

Proximal deletion of the long arm of chromosome 1: [del(1)(q23-q25)].

A patient with bilateral complete cleft of the lip and palate (CLP) had a proximal deletion of the long arm of chromosome 1 (1q). This rare chromosomal abnormality was characterized by pre- and postnatal growth retardation, psychomotor retardation, and specific craniofacial and other systemic anomalies. There is a high incidence of CLP in proximal 1q deletion syndrome, especially bilateral CLP. Twelve other cases reported in the literature having this deletion and associated anomalies were reviewed.

Abnormalities, Multiple↗
PubMed1993

Cell source and biological characteristics of murine bone marrow-derived colony-promoting activity.

A murine colony-promoting activity (CPA) was found in the supernatants of Dexter long-term bone marrow cultures (LTBMC). This activity itself failed to stimulate in vitro granulocyte-macrophage colony (CFU-GM) formation but could increase the number of colonies induced by colony-stimulating factors (CSFs). CPA was produced by the adherent stromal cells but not by the nonadherent cells. No CPA could be detected in cultures of pure marrow fibroblasts, nor was it secreted by the stromal cells following macrophage depletion. In contrast, a large amount of CPA was found in cultures of isolated macrophages, suggesting that marrow macrophages may be the main cell source of CPA. Although colony formation was augmented by adding CPA in combination with various CSFs, the colony type induced by CPA plus CSF was no different from that of CSF alone. Preincubation of bone marrow (BM) cells with CPA at 37 degrees C for 24 hours before using in clonal culture assay resulted in a marked colony enhancement. Furthermore, colony formation by 5-fluorouracil (5-FU)-treated marrow cells could be induced by granulocyte-macrophage (GM)-CSF plus CPA but not by GM-CSF alone. These results suggest that CPA may act on early developing hematopoietic stem cells to induce them to differentiate into more mature myeloid progenitor cells capable of responding to CSF stimulation. CPA was nondialyzable and stable under heat (56 degrees C for 30 minutes) and freeze/thawing (3 times). Its activity was acid-labile (pH 2.0) but relatively alkaline-resistant (pH 11.0). When treated with enzymes, CPA was sensitive to trypsin and bacterial protease but not to neuraminidase. In addition, the activity of CPA could be abrogated by anti-CPA antiserum but remained unchanged after treatment with antibodies to other murine hematopoietic synergizing/stimulating factors, including interleukin-1 (IL-1), IL-3, IL-4, IL-6, and stem cell factor (SCF).

Animals↗
PubMed1992

Facial midline and symmetry: modified face bow.

A facial "cone" can be drawn inside the head. The apex of the cone is the midpoint of the line that connects both ear canals, point C, and the face is the base. A modified face bow is designed with holes through which a Steinmann pin is passed, meeting at the apex of the facial cone. After the ear bolts are symmetrically fixed, the Steinmann pin through the central hole follows the midline of the face as the bow rotates from the forehead to the chin. The right and left facial bony protrusions can be evaluated by two Steinmann pins projecting through the corresponding holes on the face bow. This device is utilized to determine the facial midline and facial symmetry during surgery. It also can be used as a tool for anthropologic studies.

Equipment Design↗
PubMed1992

A simple and effective method of compression dressing for skin grafts.

Skin grafting is one of the most common procedures in plastic and reconstructive surgery. Various methods of fixation and dressing, to achieve good approximation and immobilization of skin grafts and, thus, to bring about better graft survival, are described. A simple method utilizing readily available latex and staples provides good fixation and compression. This technique has been applied in 50 patients requiring skin grafts. The morbidity and complications were minimal, and the grafts have taken satisfactorily. Pressure study with an animal model has revealed adequate compression.

Animals↗
PubMed1991

The human DNA-activated protein kinase phosphorylates simian virus 40 T antigen at amino- and carboxy-terminal sites.

Protein phosphorylation modulates the functions of simian virus 40 large T antigen (TAg) in productive and transforming infections. We recently described a DNA-activated protein kinase (DNA-PK) that efficiently phosphorylates TAg and several other nuclear, DNA-binding proteins in vitro (S.P. Lees-Miller, Y.-R. Chen, and C. W. Anderson, Mol. Cell. Biol. 10:6472-6481, 1990). In this report, we show by direct amino acid sequence analysis that DNA-PK phosphorylates TAg strongly at Ser-677, a residue known to be important for TAg interaction with origin site I and for transformation. We propose that DNA-PK may modulate the role of TAg in repressing early viral transcription and cell transformation, but a role for DNA-PK in regulating simian virus 40 DNA synthesis is not excluded. DNA-PK also phosphorylates Ser-665, and Ser-667, and one or more serines between amino acids 110 and 131. At least six serines, Ser-111, Ser-112, Ser-120, Ser-665, Ser-667, and Ser-677, are phosphorylated in TAg purified from baculovirus vector-infected insect cells.

Amino Acid Sequence↗
PubMed1990

Mandibular fractures in children-immediate reduction and fixation with orthodontic resin.

Mandibular fractures are not common in children. In Chang Gung Memorial Hospital from 1983 to 1987, we had 354 mandibular fractures but only 12 cases happened to children under 10 years old. Mandibular fractures in children under 10 years cannot be treated in the same way as patient with permanent teeth since possibly neither intermaxillary, nor interosseous fixation can be applied. Complication have been observed in 3 (25%) of these 12 patients, including malocclusion, infection and open bite. In 1988, orthodontic resin was adopted as the fixation material after immediate reduction in three cases. There is no complication and the patients have had a better postinjury quality of life compared with those patients treated from 1983 to 1987. The importance of immediate reduction for mandibular fracture in children and the application of resin cap splint are stressed.

Child↗
PubMed1990

[Voice disorders in children with velopharyngeal valving problems].

The purpose of this study was to examine if velopharyngeal valving problem can affect voice production (phonation) to some extent. Seventeen cleft palate children, mean age 7.0 had developed hoarseness for years without any treatment. In this study, each subject received a complete voice evaluation and the velopharyngeal (VP) function assessment. Voice evaluation included vocal cords condition and four voice parameters (quality, intensity, fundamental frequency and phonation behaviors). V-P function, classified into 3 levels (adequate, marginal & inadequate), was based on speech evaluation and instrumentations. The results showed that 41% of the subject had had bilateral vocal nodules; phonation indicated various findings in four parameters. V-P function indicated 83% of the subjects had valving problems, among which 71% had marginal V-P level. The results lead to discussion that V-P valving problems may be related with phonation disorders, because subjects like to use "compensatory behaviors" to mask their speech disorders. Among the level of valving problems, a marginal V-P function may achieve an appropriate V-P valving under compensatory behaviors and results in phonation disorders. The authors further suggest that subjects with V-P valving problems should not be subjected to the stresses of speech therapy for hypernasality because of the chance that they would compensate laryngeally for V-P problems. Meanwhile, the treatment for nodules or voice disorders should eliminate compensatory behaviors, then secondary management such as pharyngeal flap surgery for V-P problem should be considered if voice disorders persist.

Child↗