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Biomedical subjects

S W Yu

Publications and source records attributed to S W Yu.

At least 19 recordsLinked to original sources
PubMed2006

Urine protein-to-creatinine ratio in an untimed urine collection is a reliable measure of proteinuria in lupus nephritis.

OBJECTIVE: To evaluate the accuracy of urine protein-to-creatinine (P/C) ratio in an untimed urine specimen as compared with 24 h total protein excretion for measurement of proteinuria in patients with lupus nephritis. METHODS: Proteinuria in patients with lupus nephritis was assessed by 24 h total protein excretion and spot urine P/C ratio. Correlation and limits of agreement between the two methods were evaluated. The discriminant cutoff values for spot urine P/C ratio in predicting 24 h protein 'threshold' excretion of > or =0.3, > or =0.5, > or =1.0 and > or =3.5 g/day were determined using receiver operating characteristic curves. RESULTS: A total of 165 samples were available for assessment with 21.8% excluded due to inadequate collection. A strong correlation (r = 0.91, P < 0.0001) was found between spot urine P/C ratio and 24 h urine protein excretion. Bland-Altman plot showed the two tests had acceptable limits of agreement in low level of protein excretion (-0.86 to +0.92 g/day when protein excretion was <2.0 g/day). The limits became wider as the protein excretion increased. The spot urine P/C ratios of 0.45 (sensitivity 0.92; specificity 0.88), 0.7 (0.92; 0.89) and 1.84 (1.0; 0.86) mg/mg reliably predicted 24 h urine total protein equivalent 'thresholds' at > or =0.5, 1.0 and 3.5 g/day. CONCLUSION: This study supports the recommendation of using spot urine P/C ratio in screening and monitoring proteinuria in patients with lupus nephritis. However, in assessing the exact amount of proteinuria, the urine P/C ratio may have unacceptably wide limits of agreement in high protein excretion range.

Adult↗
PubMed2004

Nearest-neighbor-atom core-hole transfer in isolated molecules.

A new phenomenon sensitive only to next-door-neighbor atoms in isolated molecules is demonstrated using angle-resolved photoemission of site-selective core electrons. Evidence for this interatomic core-to-core electron interaction is observable only by measuring nondipolar angular distributions of photoelectrons. In essence, the phenomenon acts as a very fine atomic-scale sensor of nearest-neighbor elemental identity.

Journal Article↗
PubMed2003

Dramatic nondipole effects in low-energy photoionization: experimental and theoretical study of Xe 5s.

The Xe 5s nondipole photoelectron parameter gamma is obtained experimentally and theoretically from threshold to approximately 200 eV photon energy. Significant nondipole effects are seen even in the threshold region of this valence shell photoionization. In addition, contrary to previous understanding, clear evidence of interchannel coupling among quadrupole photoionization channels is found.

Journal Article↗
PubMed2001

Treatment of distal clavicle fracture using Kirschner wires and tension-band wires.

BACKGROUND: Nonunion frequently follows distal clavicle fracture. Traditional pinning methods using the through acromioclavicular articulation may result in osteoarthritic changes or ankylosis. This study introduces a direct pinning technique in which the acromioclavicular joint is spared. METHODS: Twelve patients with displaced distal clavicle fractures received open reduction and fixation with Kirschner wires (K-wires) and tension-band wires, from May 1996 to March 1997. The indication for surgery was type IIa fracture or fracture with displacement. Unrestricted passive and active range of motion was performed as soon as possible after the operation. Stretching and exertional exercises were permitted after radiographs showed an osseous union and after the implants were removed. RESULTS: Eleven patients achieved osseous union with painless full motion. Union time ranged from 3 to 6 months. One patient suffered from more comminuted fracture because of a fall 2 months after operation. This patient received a revision surgery with distal clavicle resection and coracoclavicle reconstruction. Symptomless ossification around the coracoclavicle ligament was noted on radiographs in one patient. The ossification did not progress after the 9-month follow-up. CONCLUSION: Edwards reported a rate of 45% delayed union and 30% nonunion in type II fractures. Several techniques had been described in the relevant literature. In our practice, fixation with Kirschner wires and tension-band wires has been successful in the treatment for displaced distal clavicle fracture.

Accidental Falls↗
PubMed2001

188rhenium-TDD-lipiodol in treatment of inoperable primary hepatocellular carcinoma--a case report.

INTRODUCTION: The aim of this study was to investigate the potential of using 188Re Lipiodol for selective internal radiation therapy of inoperable hepatocellular carcinoma (HCC). CLINICAL PICTURE: A 33-year-old female with poorly-differentiated multicentric HCC, elevated alpha-fetoprotein (AFP) and increased serum alkaline phosphatase. TREATMENT: Over a 2-month interval, the patient was treated twice with 4GBq of 188Re-TDD-Lipiodol. OUTCOMES: There was good localisation of 188Re Lipiodol in the tumours, but also in thyroid (first treatment) and gastrointestinal tract (both treatments). So far (5 months post-treatment), the patient remains well with stable disease. CONCLUSIONS: 188Re Lipiodol can be an effective radiopharmaceutical for the treatment of HCC; however, more work must be done to minimise the uptake in bowel.

Adult↗
PubMed2000

MicroStructured Omnifit acetabular components: concerns with locking system complications and excessive polyethylene wear.

BACKGROUND: We began to use cementless MicroStructured Omnifit acetabular components in November 1988. Liner dislodging and excessive polyethylene wear later occurred in some of our patients. This finding prompted us to review our experience with the use of such modular acetabular components. METHODS: A total of 887 hips in 672 patients, which had been fitted with cementless MicroStructured Omnifit acetabular components, were evaluated for locking system complications using radiographic examinations. Of the cases, 240 hips which had received a 26-mm femoral head (group 1) and 110 hips which had received a 32-mm femoral head (group 2) were compared using a digitiser to determine the influence of femoral head size on polyethylene wear. RESULTS: There were two types of radiographic signs of locking system complications in 7 hips, at a mean time of 2.9 years after implantation. The incidence of liner locking system complications using this modular acetabular component was 0.8%. The mean liner wear rate per year was 0.15 mm in group 1 and 0.20 mm in group 2 (p <0.005). The initial polyethylene thickness ranged from 5.9 to 13.6 mm in group 1, compared with 3.9 to 10.6 mm in group 2 (p < 0.005). CONCLUSION: A patient who has received a total hip arthroplasty that includes a MicroStructured Omnifit acetabular component should be monitored frequently for radiographic signs of locking system complications. In this study, the mean liner wear rate was significantly higher in group 2. Inadequate polyethylene thickness in this group was implicated as the major cause of excessive polyethylene wear.

Adolescent↗
PubMed1999

Spectral characterization and chemical modification of FMN-containing ascorbyl free-radical reductase from Pleurotus ostreatus.

Ascorbyl free-radical reductase was purified 1143-fold with an overall yield of 9.9% from the cytosolic fraction of Pleurotus ostreatus. The native enzyme had a molecular mass of 127 kDa and SDS/PAGE revealed that the enzyme consists of two subunits, each with a molecular mass of 62 kDa. The enzyme utilized only NADH as an electron donor. The enzyme was highly specific for ascorbyl free radical as an electron acceptor and capable of catalysing the reduction of ferricyanide and 2,6-dichloroindophenol as artificial electron acceptors. The apparent K(m) values of the enzyme towards NADH and ascorbyl free radical were 35+/-0.22 and 2.1+/-0.03 microM, respectively. The catalytic mechanism of this enzyme is of Ping Pong type. The enzyme contained FMN as a prosthetic group and showed the characteristic absorption spectrum ascribed to the charge-transfer interaction of thiolate anion with FMN. The enzyme contained eight cysteine residues per monomer and was inactivated more rapidly by mercurials than by thiol-alkylating reagents. Kinetic analysis of the inactivation process revealed that the enzyme had 1 mol of thiol group/mol of subunit in the active site with a pK(a) of 6.9. The modification of the thiol group of the enzyme caused the loss of charge-transfer absorbance centred at 540 nm and blocked the electron-transfer process from NADH to FMN. The modification of lysine, arginine and histidine residues led to the loss of its activity. Unlike the active enzyme, the fluorescence quenching of NADH was not observed in the lysine-modified enzyme, which implies that lysine residues can participate in the interaction with NADH.

Enzyme Inhibitors↗
PubMed1999

Radionuclide studies of articular cartilage in the early diagnosis of arthritis in the rabbit.

The compound Se-75 bis[beta-(N,N,N-trimethylamino-)ethyl]selenide diiodide (Se-75 BISTAES) has been synthesized and its biodistribution in rabbits studied. A high uptake of radioactivity is found in the knee cartilage. Good scans of the knee are obtained by nuclear scintigraphy at 15 minutes after the injection of Se-75 BISTAES. The results of an equilibrium dialysis study show that Se-75 BISTAES binds to chondroitin sulfate and the binding is directly proportional to the chondroitin concentration. It appears that Se-75 BISTAES or its derivative should have potential as an articular imaging agent.

Animals↗
PubMed1999

Anterior knee pain after intramedullary tibial nailing.

BACKGROUND: Currently, intramedullary nailing is a well-accepted method for treating tibial shaft fractures, but some patients complain of anterior knee pain after surgery. Multiple factors may influence this troublesome complication. METHODS: This was a retrospective analysis of the medical records of 200 patients who were treated with intramedullary nailing after tibial shaft fractures. Sixty-four patients complained of knee pain after surgery. We evaluated the knee pain in relation to the surgical approach, radiographic readings, and the type of nail used. RESULTS: Among the 64 patients, 45 (70%) received central approaches and 19 (30%) received paramedial approaches (p = 0.0002); 46 patients (72%) showed nail protrusions on radiographs and only 18 patients (28%) were without nail impingement (p = 0.0001). Forty-three patients (67%) received Kuntscher nail fixation and just 21 patients (33%) had interlocking nail fixation (p = 0.0015). CONCLUSION: The use of the central patellar tendon splitted approach, nail protrusion observed on radiographs, and the insertion of a non-locking intramedullary nail were all significant risk factors for anterior knee pain after surgery. All these risk factors should be avoided in tibial nailing to decrease the problem of postoperative knee pain.

Fracture Fixation, Intramedullary↗
PubMed1996

A heme-containing ascorbate oxidase from Pleurotus ostreatus.

A novel type of ascorbate oxidase was purified 420-fold from the cytosolic fraction of the mycelia of Pleurotus ostreatus with an overall yield of 13%. The molecular mass of the native enzyme determined by high performance gel permeation chromatography was 94 kDa. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the enzyme consists of two subunits with a molecular mass of 46 kDa. The N-terminal amino acid sequence of the enzyme was Asp-Val-Lys-Thr-Leu-Gln-Glu-His-Leu-Gln-Leu-Ala-Leu-Met-Val-. The enzyme was optimally active at pH 5.2, monitored at 37 degrees C. The enzyme had affinity toward L-ascorbic acid, D-ascorbic acid, L-erythroascorbic acid, and D-erythroascorbic acid. Under optimal conditions, the Km value of the enzyme toward L-ascorbic acid was 0.48 mm. The absorption spectra of the native enzyme exhibited a Soret maximum at 418 nm in its oxidized form and at 426 nm in its reduced form, and alpha and beta bands at 558 and 527 nm only in its reduced form, respectively. On the basis of spectral changes after treatment with cyanide and carbon monoxide, the enzyme is a hemoprotein, quite similar to b-type cytochrome, and contains 2 mol of heme per molecule. The reaction catalyzed by the enzyme was L-ascorbic acid + O2 --> dehydro-L-ascorbic acid + H2O2.

Amino Acid Sequence↗
PubMed1995

Surgical correction of muscular torticollis in older children.

BACKGROUND: Children with muscular torticollis treated before the age of 1 year respond well to conservative treatment. Surgical correction is indicated only in resistant cases. Nevertheless, there is still controversy about the results and the type of operation in the management of neglected older children. METHODS: Seventeen patients, at a mean age of 9 years and 5 months, with muscular torticollis were surgically treated between 1986 to 1991. The average follow-up period was 3 years and 4 months. months. Combined approach with open tenotomy at mastoid and clavicular level was the choice of procedure. The outcome for these older children and young adults were evaluated with function and cosmesis. RESULTS: Our results showed that the best results can be expected in children before 12 years of age. Late releases give acceptable results, although facial asymmetry and some residual upper dorsal scoliosis remain. Adequate surgical release and intensive postoperative physical therapy are the keystones to a good result. CONCLUSIONS: Surgical correction of muscular torticollis in the older children is of benefit for functional and cosmetic recovery, but facial asymmetry is irreversible after 12 years of age.

Adolescent↗
PubMed1990

Age-related changes in the cervical facet joints: studies with cryomicrotomy, MR, and CT.

The cervical facet joints of 20 cadavers were studied systematically with MR, CT, cryomicrotomy, and histologic sections to determine the anatomic changes that occur with age. Uniform layers of cartilage and subarticular cortical bone characterize the cervical facet joints in cadavers under 20 years of age. Most adult cervical facet joints have only a discolored or microscopically thin layer of cartilage and have irregularly thickened subarticular cortical bone. The appearance of the cervical facet joints changes significantly with aging.

Adult↗
PubMed1988

Ligamentum flavum: appearance on sagittal and coronal MR images.

The appearance of the ligamentum flavum on sagittal and coronal magnetic resonance (MR) images has not been described in detail in the radiologic literature. The authors reviewed correlative MR images and anatomic sections obtained with a cryomicrotome in 20 cadavers in order to analyze anatomic relationships, variations, and progressive degenerative changes of the ligamentum flavum in the lumbar region. MR imaging showed the ligamentum flavum as an intermediate-signal-intensity structure on images obtained with short and long repetition times (TRs). Sagittal short TR images were effective for evaluating relationships between the ligamentum flavum, spinal canal, and nerve roots. Degenerative changes in the ligamentum flavum appeared as changes in shape or thickness of the ligaments on MR images. Calcification and fat infiltration, which were well depicted on anatomic sections, were not visualized on MR images.

Cadaver↗
PubMed1988

Progressive and regressive changes in the nucleus pulposus. Part I. The neonate.

Magnetic resonance (MR) imaging, correlated with anatomic sections, was used to characterize the progressive and regressive changes in the nucleus pulposus in neonates. The spines of five fetuses and five full-term infants between 16 and 40 weeks old were studied. In anatomic sections, the nucleus pulposus was sharply demarcated from the anulus fibrosus, Sharpey fibers were conspicuous, and a plate of primitive notochord was evident in the equator of the disk. On long repetition time (TR)/long echo time (TE) or long TR/short TE MR images, Sharpey fibers (low signal intensity) and notochord (low signal intensity) could be differentiated from the high-signal-intensity nucleus pulposus and anulus fibrosus. The major differences between the fetal and infant spines were the amount of notochord in the disk and ossification in the vertebral body.

Cadaver↗
PubMed1988

Progressive and regressive changes in the nucleus pulposus. Part II. The adult.

The spines of 28 cadavers were studied with magnetic resonance (MR) imaging, correlated with anatomic sections, to characterize the progressive and regressive changes in the nucleus pulposus. Four additional types of nucleus pulposus were identified in this study. The transitional type (type II) of childhood had fibrous tissue that developed near the anulus fibrosus anteriorly or posteriorly. MR images showed a notch of reduced signal intensity in the nucleus pulposus where the fiber was developing. The adult type (type III), which is predominant after age 30 years, had an indistinct boundary between the nucleus pulposus and anulus fibrosus. MR images showed the fibrocartilage in the nucleus pulposus and inner anulus fibrosus as areas of high signal intensity. Adult disks with a tear of the anulus fibrosus (type IIIB) had a lower signal intensity on MR images and slightly reduced disk heights. This type may represent an early stage of degeneration. Degenerated intervertebral disks (type IV) had either dense disorganized fibrous tissue or fluid replacing the normal fibrocartilaginous structure of the nucleus pulposus. MR images showed narrow intervertebral disk spaces with either reduced signal intensity if collagen was present or increased signal intensity if fluid was present. This study suggests that the nucleus pulposus may progress normally through types I, II, and III.

Adult↗
PubMed1988

Cervical neural foramina: correlative anatomic and MR imaging study.

Accurate diagnosis of diseases affecting the cervical neural foramina with magnetic resonance (MR) imaging requires an appreciation of the normal anatomic appearance of the foramen. The MR appearance of the foramen was studied in cadavers and healthy volunteers and was correlated with cadaver cryomicrotome sections. With gradient-echo techniques, foraminal soft tissues are highlighted relative to adjacent bone, making gradient-echo images valuable for evaluating the overall size and contents of the neural foramina. Intravenously administered gadolinium DTPA produces enhancement of all foraminal soft tissues, including the dorsal root ganglion. The nerve roots do not enhance with Gd-DTPA. Gradient-echo pulse sequences and intravenous use of Gd-DTPA represent promising techniques for the evaluation of the cervical foramina.

Cervical Vertebrae↗