Biomedical subjects

Y R Chen

Publications and source records attributed to Y R Chen.

At least 19 recordsLinked to original sources

PubMed1995

A signature of the oxygenase intermediate in catalysis by ribulose-bisphosphate carboxylase/oxygenase as provided by a site-directed mutant.

An uncharacterized minor transient product, observed in our earlier studies of substrate turnover by the E48Q mutant of Rhodospirillum rubrum ribulose-bisphosphate carboxylase/oxygenase (Lee, E. H., Harpel, M. R., Chen, Y.-R., and Hartman, F. C. (1993) J. Biol. Chem. 268, 26583-26591), becomes a major product when it is trapped and stabilized with borate as an additive to the reaction mixture. Chemical characterization establishes this novel product as D-glycero-2,3-pentodiulose 1,5-bisphosphate, thereby demonstrating oxidation of the C-3 hydroxyl of D-ribulose 1,5-bisphosphate to a carbonyl. As the formation of the novel oxidation product is oxygen-dependent and generates hydrogen peroxide, its precursor must be a peroxy derivative of ribulose bisphosphate. Thus, discovery of the dicarbonyl bisphosphate lends direct support to the long standing, but heretofore unproven, postulate that the normal pathway for oxidative cleavage of ribulose bisphosphate by the wild-type enzyme entails a peroxy intermediate. Our results also suggest that stabilization of the peroxy intermediate by the wild-type enzyme promotes carbon-carbon scission as opposed to elimination of hydrogen peroxide.

Bacterial Proteins↗

PubMed1995

Identification of amino acid residues involved in structural and ubiquinone-binding functions of subunit IV of the cytochrome bc1 complex from Rhodobacter sphaeroides.

Previous studies established that subunit IV of the cytochrome bc1 complex from Rhodobacter sphaeroides is involved in structural and ubiquinone-binding functions of the complex. To identify regions or amino acid residues responsible for these functions, deletion, insertion, and substitution mutations at various regions of subunit IV were generated and characterized. Mutational effects on the structural role of subunit IV are indicated by a delay in photosynthetic growth and by a decrease in the cytochrome bc1 complex activity in chromatophores upon detergent treatment. An effect on the ubiquinone-binding function of subunit IV is suggested by an increase in the apparent Km for 2,3-dimethoxy-5-methyl-6-geranyl-1,4-benzoquinol (Q2H2) of the complex. RSIV delta (2-5), in which residues 2-5 are deleted, had photosynthetic growth behavior, tolerance to detergent treatment, and an apparent Km for Q2H2 of its cytochrome bc1 complex similar to those of wild-type or complement cells, indicating that amino acid residues 2-5 are not essential for subunit IV function. RSIV delta (2-11), with residues 2-11 missing, showed a 24-h delay in photosynthetic growth and a 65% inactivation of the cytochrome bc1 complex upon dodecyl maltoside solubilization. However, its apparent Km for Q2H2 was the same as in wild-type cells, indicating that deletion of amino acid residues 6-11 results in loss of the structural but not the ubiquinone-binding function of subunit IV. RSIV delta (113-124), which has 13 amino acid residues deleted from the C terminus, had photosynthetic growth behavior, tolerance to detergent treatment, and ubiquinone-binding kinetics similar to those of wild-type or complement cells, indicating that residues 113-124 are not essential. Point mutants RSIV(W79L) and RSIV(W79F), in which tryptophan 79 was replaced with leucine or phenylalanine, showed a 24-h delay in photosynthetic growth, a decrease of 75% of the cytochrome bc1 complex activity in chromatophores upon detergent solubilization, and a 4-fold increase in the apparent Km for Q2H2, indicating that Trp-79 is essential for the structural and ubiquinone-binding functions of subunit IV.

Amino Acid Sequence↗

PubMed1995

Polyotia.

Polyotia is an extremely rare congenital anomaly of the external ear. Only four case reports are documented in the literature. A 13-month-old child with a mirror-image duplication of the left auricle was operated on in a one-stage corrective procedure. The duplicated portion of the affected ear was positioned anteriorly and measured approximately two-thirds the size of the posterior, normally oriented portion. There were two fully developed conchae and one fully developed and one partially developed anthelix and lobule. The entire complex had a single external auditory meatus and no tragus. There were no other congenital anomalies, and the child was developmentally normal. The technique for surgical correction is described, and a review of the literature is presented.

Ear, External↗

PubMed1995

Short gracilis myocutaneous flaps for vulvoperineal and inguinal reconstruction.

From October of 1990 to April of 1993, 16 short gracilis myocutaneous flaps and 1 short gracilis muscular flap were used to reconstruct vulvoperineal, inguinal, perineal, and ischial soft-tissue defects. Five of the 6 bilateral myocutaneous flaps were used for vulvoperineal reconstruction after radical vulvectomy combined with partial vaginectomy and one radical vulvectomy. Four unilateral myocutaneous flaps and one muscular flap were used for inguinal, suprapubic, ischial, and perineal reconstruction after release of contracted scar or excision of an ischial pressure sore. The immediate complications consisted of partial necrosis of the distal third of the cutaneous tissue in 6 patients, 1 superficial cutaneous necrosis, and superficial wound infection in 7 patients. The muscular portion of the flaps all survived. The follow-up period was from 6 to 27 months. The short gracilis flap has greater mobility than the classically described gracilis flap. On the basis of the functional and cosmetic results, the short gracilis flap is an excellent alternative to the more bulky classic gracilis flap.

Adolescent↗

PubMed1995

Skull morphology affected by different sleep positions in infancy.

In infancy, prior to cranial suture and fontanel calcification, the craniofacial skeleton can be easily deformed by an externally exerted force. In this study, the relationship between the sleep position and skull morphology was investigated. A group of 81 cleft lip and/or palate infants without other systemic anomalies was first seen in the craniofacial center at approximately 1 month of age. The sleep position of each infant was recorded as supine, prone, or mixed type. The body and skull growth were longitudinally measured at 1, 3, and 6 months of age. Infants sleeping in the supine sleep position tended to have a wider head width, shorter head length, and a larger cephalic index by 6 months of age. The opposite phenomena were observed in the prone sleep group. The mixed sleep group tended to have head width, head length, and cephalic index between those of the supine sleep group and the prone sleep group. During the first 3 months of life, the sleep position could mold the skull primarily in the dimension of head width. In conclusion, the supine sleep position may promote brachycephaly and the prone sleep position dolichocephaly.

Age Factors↗

PubMed1995

Unusual complications of the Le Fort I osteotomy.

In this report we describe three very different and interesting complications of the Le Fort I osteotomy. The first case is of a unilateral third nerve palsy developing as a result of a carotid-cavernous fistula and false aneurysm of the internal carotid artery. The second complication to be reported is total unilateral blindness. The third case is one of total avulsion of a lateral segment of the palate in a patient with a complete bilateral cleft of the primary and secondary palates. All complications were the result of a Le Fort I osteotomy performed for correction of midface hypoplasia secondary to congenital cleft lip and palate. The literature is reviewed, and the pathomechanics of each injury are hypothesized.

Adolescent↗

PubMed1995

Surgical complications of the Le Fort I osteotomy--a retrospective review of 146 cases.

A retrospective review of 146 cases with Le Fort I osteotomy performed between 1981 and 1990 is presented. A complication of 6.1% was recorded. These complications include intraoperative hemorrhage, trigeminal nerve injury, oronasal fistula and dental injury. Although the Le Fort I osteotomy has proven to be relatively safe, improvements in technique will further reduce the incidence and the severity of complications.

Adolescent↗

PubMed1995

[Postoperative evaluation in mandibular prognathism treated by bilateral sagittal split osteotomy].

The present study was undertaken to evaluate the postoperative relapse from the period of unwiring to 1 year postoperatively and its correlation to the amount of mandibular setback and change in vertical dimension after mandibular bilateral sagittal split osteotomy. Twenty-seven patients were evaluated cephalometrically by the time preoperatively, 6 weeks, 6 months and 1 year postoperatively. It was found that 1) the average amount of mandibular setback at pogonion point, 6 weeks postoperatively, is 7.6mm backward and 1.9mm downward, 2) the average amount of horizontal relapse at pogonion point, 6 months and 1 year postoperatively, are 1.9mm and 2.3mm respectively. 86% of the horizontal relapse, 1 year postoperatively, occurs in the first 6 months after removal of intermaxillary fixation, 3) the average amount of vertical relapse at pogonion point, 6 months and 1 year postoperatively, are 0.9mm and 1.1mm upward. 82% of the vertical relapse, 1 year postoperatively, occurs in the first 6 months after removal of intermaxillary fixation, 4) the amount of 1 year postoperatively horizontal relapse is significantly correlated both with the amount of horizontal mandibular set back and vertical downward change (r = 0.58, 0.67, p < 0.001), whereas the amount of vertical relapse is with the vertical downward change only, but horizontal setback isn't.

Adolescent↗

PubMed1995

A clinical study of colorectal cancer accompanied by cancer of other organs.

BACKGROUND: The incidence of double primary neoplasms has increased in recent decades. The etiologies and epidemiologies of double primary neoplasms are under investigation, and relationships between some cancers are well established. A group of patients with double primary cancers was studied to determine the relationships between certain cancers. METHODS: From November 1982 to September 1993, 48 patients with colorectal cancer accompanied by cancer of another organ (double primary cancers) were treated here. The male-to-female ratio was 31 to 17. According to Warren's definitions, the patients were classified into two groups: synchronous and metachronous. Data collection was done on the basis of locations, pathological staging and interval between cancers. RESULTS: Among the 48 patients, extracolonic cancers were mainly found in the cervix (8), stomach (7), prostate (5), lung (5), urinary bladder (4), and breast (4). In the female patients, 88.2% (15/17) of extracolonic cancers were in the female reproductive organs. In male patients, 45% (14/31) of extracolonic cancers were GI tract neoplasms, and 35.5% (11/31) were cancers of the GU tract. Nearly half of the patients expired within two years after diagnosis of the second primary cancer. CONCLUSIONS: Cancers of the cervix, stomach, prostate, lung, urinary bladder and breast may have some etiologic factors in common with that of colorectuim. Thus, attention should be paid to these sites during the period of post-operative follow-up of the first primary cancer.

Adult↗

PubMed1995

Augmentation of the free border of the lip in cleft lip patients using temporoparietal fascia.

Deficiency of the free border of the lip is frequently encountered in secondary cleft lip deformities. The free border of the lip consists of the orbicularis oris marginalis muscle and its overlying subcutaneous tissue, vermilion, and mucosa. The pathology may involve any or all of these components. When there is an absolute shortage of subcutaneous tissue or orbicularis oris marginalis muscle, extra tissue from another source must be used for augmentation. A temporoparietal fascial graft is a simple and reliable method to increase the fullness of the free border of the lip. The tissue is soft in consistency and displays minimal resorption. Most important, more complicated procedures such as an Abbé flap or tongue flap may be avoided. From July of 1988 until June of 1992, the temporoparietal fascial graft was used successfully to correct deficiencies of the free border of the lip in 20 patients with cleft lip deformities. There were two graft exposures that healed with conservative treatment. The procedure is a useful method of augmenting both lateral lip and central lip deficiencies in secondary and tertiary cleft lip deformities.

Adolescent↗

PubMed1994

Role of subunit IV in the cytochrome b-c1 complex from Rhodobacter sphaeroides.

Rhodobacter sphaeroides mutants lacking subunit IV (M(r) = 14,384) of the cytochrome b-c1 complex (representative mutant strain, RS delta IV-2) have been constructed by site-specific recombination between the wild-type genomic subunit IV structural gene (fbcQ) and a suicide plasmid containing a defective fbcQ sequence. RS delta IV-2 gives rise to a photosynthetically competent phenotype after a period of adaptation. The chemical compositions, spectral properties, and cytochrome b-c1 complex activities in subunit IV-deficient chromatophores from adapted RS delta IV-2 are similar to those in wild-type chromatophores. However, the apparent Km for Q2H2 for the b-c1 complex in subunit IV-deficient chromatophores from adapted RS delta IV-2 cells is about four times higher than that in chromatophores from wild-type cells. The cytochrome b-c1 complex activity in subunit IV-deficient chromatophores of adapted RS delta IV-2 cells is more labile to detergent treatment than that from wild-type cells. The specific activities of dodecylmaltoside-solubilized fractions of RS delta IV-2, based on cytochrome b, are only one-fourth that of the untreated chromatophores. Introducing a wild-type fbcQ operon on a stable low copy number plasmid, pRK415, into RS delta IV-2 restores photosynthetic growth behavior, the apparent Km value for Q2H2, and tolerance to detergent treatment to that of wild-type cells. Cytochrome b-c1 complex purified from adapted RS delta IV-2 contains only three subunits. It has only 25% of the activity of the four-subunit enzyme. This low activity is accompanied by an increase of the apparent Km for Q2H2 from 3 to 13 microM, suggesting that subunit IV may be involved in quinone binding in addition to its structural role.

Base Sequence↗

PubMed1994

Expression of alpha-amylases, carbohydrate metabolism, and autophagy in cultured rice cells is coordinately regulated by sugar nutrient.

A rice suspension cell culture system has been established to study how sugar depletion regulates alpha-amylase expression, carbohydrate metabolism, and other physiological and cellular changes. It is shown here that a group of 44 kDa alpha-amylases are constitutively expressed whether or not the cells are starved of sucrose. However, expression of a new group of alpha-amylases of 46 kDa is dramatically induced when cells are starved of sucrose. Cellular sugar and starch were rapidly consumed and metabolic activity was decreased in the starved cells. Extensive autophagy also occurred in the starved cells, which caused an increase in vacuolar volume and degradation of cytoplasmic constituents including amyloplasts. Immunocytochemical studies revealed that alpha-amylases are localized in starch granules within amyloplasts, in cell walls, and in some of the vacuoles. The presence of putative signal sequences in the N-termini of nine rice alpha-amylases suggests hitherto unidentified pathways for import of alpha-amylases into amyloplasts. The studies show that differential alpha-amylase expression, carbohydrate metabolism, metabolic activity, and vacuolar autophagy are coordinately regulated by the sugar level in the medium. As the starved suspension cells exhibit some sugar-regulated characteristics of alpha-amylase expression in germinating rice embryos as well as physiological changes similar to those in senescing cells, this system represents an ideal tool for studying cellular, biochemical, and molecular biological aspects of alpha-amylase gene regulation, carbohydrate metabolism, senescence, and protein targeting in plants.

Amino Acid Sequence↗

PubMed1994

Cleft lip and hemangioma: a patient with Wolf-Hirschhorn syndrome.

A patient with Wolf-Hirschhorn syndrome had multiple congenital anomalies and a right cleft lip. Hemangioma involved the full thickness of the upper medial lip segment at the age of 2 months, which caused lip repair to be very difficult. The first attempt at adhesion cheiloplasty resulted in complete separation. The tumor did not respond to steroid treatment. A subsequent trial of lip repair with the assistance of a tension-relieving suture tied to the nasal septum was successful. This type of tension suture is helpful to prevent dehiscence when security of lip closure is questionable or cannot be achieved.

Abnormalities, Multiple↗

PubMed1994

Maxillary involvement in central craniofacial fractures with associated head injuries.

From January 1983 through December 1990, we treated 703 patients with central craniofacial fractures. Among them 177 had maxillary fractures, with or without frontonasoethmoidal involvement. Of the 177, 151 patients were diagnosed in the acute stage. Using the Glasgow Coma Scale, these 151 patients were divided into three groups: group I (GCS score 13-15), 100 patients; group II (GCS score 9-12), 33 patients; group III (GCS score 3-8), 18 patients. The patterns of facial fractures were analyzed and surgically corrected after the following average postadmission lags: group I, 7.1 days; group II, 11.5 days; group III, 13.3 days. The average hospital stay for each group was: group I, 15.6 days; group II, 19.5 days; and group III, 27.2 days. The mean follow-up period was 12 months. The physiologic, functional and esthetic outcomes were assessed. Regardless of initial head injury severity, the outcomes in each group showed almost no statistically significant differences, and unnecessary extended hospital stays may be avoided by early surgical management.

Adolescent↗

PubMed1994

Identification and purification of a protein that induces production of the Lactobacillus acidophilus bacteriocin lactacin B.

Lactacin B is a heat-stable bacteriocin produced by Lactobacillus acidophilus N2 that is active against closely related lactobacilli, including Lactobacillus delbrueckii subsp. lactis (formerly Lactobacillus leichmannii) ATCC 4797. Pure producer cultures propagated in MRS broth (initial pH 6.5) contain no lactacin B; it is detected only in cultures maintained at pH 5.0 to 6.0 and produced optimally at pH 6.0 S. F. Barefoot and T. R. Klaenhammer, Antimicrob. Agents Chemother. 26:328-334, 1984). Associative growth of producer and indicator, L. delbrueckii subsp. lactis ATCC 4797, resulted in production of an inhibitor identical to lactacin B. Associative growth increased lactacin B production from nondetectable levels (< 100 activity units [AU]/ml) to between 3,200 and 6,400 AU/ml in MRS broth (initial pH 6.5) and resulted in early but equal production of lactacin B (approximately 25,600 AU/ml) in broth maintained at pH 6.0. Indicator cells, but not spent culture filtrates, induced lactacin B production. Indicator cells disrupted by a French pressure cell yielded cell-free filtrates containing inducing activity. Chromatofocusing and gel filtration high-performance liquid chromatography of cell-free filtrates yielded a protein with a pI of 4.1 and a molecular size of approximately 58 kDa that induced lactacin B production. Analytical isoelectric focusing yielded a single protein band. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels contained a 28-kDa protein suggesting a two-subunit structure. Protein sequencing identified an N-terminal serine and 18 additional amino acids. To our knowledge, there are not previous descriptions of proteins that induce bacteriocin production in lactic acid bacteria.

Amino Acid Sequence↗

PubMed1994

In vitro investigation of blood compatibility of Ti with oxide layers of rutile structure.

Structure characteristics of titanium oxide layer on titanium matrix were investigated by Rutherford Backscattering Spectroscopy (RBS), Auger Electron Spectroscopy (AES) and X-ray diffraction. It has been identified that the titanium oxide layers had rutile structure. The blood compatibility of the titanium oxide layers of different thickness was studied by blood clotting time measurement. It was shown that as the thickness of the titanium oxide layers increased, blood compatibility of these layers was obviously improved.

Animals↗

PubMed1994

Maxillary dental arch affected by different sleep positions in unilateral complete cleft lip and palate infants.

The development of the dental arch is well designed for adaptive and compensatory growth. In this study, the relationship between the sleep position and dental arch development was investigated. A group of 42 infants with unilateral complete cleft lip and palate with either prone (16) or supine (26) sleep position were seen in the craniofacial center. All infants were less than 1 month of age at the initial visit. Dental impressions of the maxillary arch were taken at the initial visit and just before cheiloplasty. Ten arch dimensions were measured in each dental cast and the longitudinal change in each dimension was compared between the prone sleep group and the supine sleep group. Statistically significant changes were detected in the growth rate of the following dimensions: intercanine width, intertuberosity width, alveolar cleft width, anterior cleft width, and posterior cleft width. This study indicated that sleep position affected maxillary arch development. Infants sleeping in the prone sleep position tended to have narrower arch width and cleft width.

Analysis of Variance↗

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↗