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Biomedical subjects

S Y Lin

Publications and source records attributed to S Y Lin.

At least 91 records · Page 5Linked to original sources
PubMed2000

Open total talar dislocation--report of two cases.

Total dislocation of talus from all its surrounding joints (tibiotalar, subtalar and talonavicular) is an extremely rare injury. Because of its rarity, only few case reports can be found in the literature. In the review of the literature, infection and AVN are the most commonly encountered complications that affect the outcome of these severe injuries. Herein we report two cases of open total talar dislocation. Immediate debridement, reduction of the talus, and primary skin closure was done followed by cast immobilization. After more than 2 years follow up, neither infection nor AVN was found. We conclude that reimplantation of the talus is preferable if the wound is relatively clean. Talectomy, or combined with tibiocalcaneal fusion should be reserved for later salvage procedure.

Adult↗
PubMed2000

Failure of the locking mechanism between the acetabular metal shell and the polyethylene liner after primary total hip arthroplasty--a case report.

The short and intermediate-term clinical and radiographic results associated with Harris-Galante II porous-coated acetabular modular cup without cementing have been excellent in most patients. Nevertheless, its modular design introduced the potential for failure of the locking mechanism. There are four pairs of locking ties on the rim of metal shell to fix the polyethylene liner within it. Failure of any locking tine would result in less rigid fixation between the metal shell and the polyethylene liner and potentially produce instability or even disassembling of the liner. Only nine cases have been reported previously about the fractures of the locking tine, but it has never been reported in literature in Taiwan. We report a case with fracture of one tine following minor trauma at five years after primary total hip arthroplasty. During reoperation, scratching injury on the outer surface of the polyethylene liner in contact with the inferior tines of the metal shell was noted. Although no disassembling of the liner was noted, the remaining locking mechanism was found to be less rigid when the liner was taken out of the shell. The locking mechanism of HG II cup may be mechanically weak and may fail without major trauma; therefore, its design ought to be improved in an attempt to prevent postoperative dissociation of the polyethylene liner.

Acetabulum↗
PubMed2000

Percutaneous release of abductor pollicis brevis muscle fibrosis in a bowler--a case report.

The authors reported a patient with abductor pollicis brevis muscle fibrosis of the right thumb, stemming from a bowling injury that had occurred 6 years previously. At that time in the acute stage, a Chinese bonesetter treated the injury using manipulation, massage and herbal drugs. Abduction contracture of the patient's right thumb developed. She began to experience chronic pain at dorsal side of her right thumb and discovered that she could not move her thumb into a retro position. When she came into our hospital, physical examination revealed an abduction contracture of patient's right thumb, the angle of separation was 60 degrees, and the angle of circumduction was fixed at 90 degrees. In addition, a fibrotic band was palpable in abductor pollicis brevis muscle. The patient responded well to percutaneous release and physical therapy. As far as we know, this is an unusual case, which has not been reported before.

Adult↗
PubMed1999

E1A sensitizes cells to tumor necrosis factor-induced apoptosis through inhibition of IkappaB kinases and nuclear factor kappaB activities.

The adenovirus E1A protein has been implicated in increasing cellular susceptibility to apoptosis induced by tumor necrosis factor (TNF); however, its mechanism of action is still unknown. Since activation of nuclear factor kappaB (NF-kappaB) has been shown to play an anti-apoptotic role in TNF-induced apoptosis, we examined apoptotic susceptibility and NF-kappaB activation induced by TNF in the E1A transfectants and their parental cells. Here, we reported that E1A inhibited activation of NF-kappaB and rendered cells more sensitive to TNF-induced apoptosis. We further showed that this inhibition was through suppression of IkappaB kinase (IKK) activity and IkappaB phosphorylation. Moreover, deletion of the p300 and Rb binding domains of E1A abolished its function in blocking IKK activity and IkappaB phosphorylation, suggesting that these domains are essential for the E1A function in down-regulating IKK activity and NF-kappaB signaling. However, the role of E1A in inhibiting IKK activity might be indirect. Nevertheless, our results suggest that inhibition of IKK activity by E1A is an important mechanism for the E1A-mediated sensitization of TNF-induced apoptosis.

Adenovirus E1A Proteins↗
PubMed1999

Brain-derived neurotrophic factor enhances association of protein tyrosine phosphatase PTP1D with the NMDA receptor subunit NR2B in the cortical postsynaptic density.

Our recent studies revealed that brain-derived neurotrophic factor (BDNF) rapidly enhances tyrosine phosphorylation and dephosphorylation of the NMDA receptor subunit, NR2B, in the postsynaptic density (PSD), potentially regulating synaptic plasticity. To explore the molecular mechanisms underlying synaptic NR2B signaling, we examined the protein tyrosine phosphatase, PTP1D; BDNF reportedly increases association of PTP1D with tyrosine phosphorylated proteins in cortical neurons and PC 12 cells. We now report that PTP1D is an intrinsic component of the rat cerebrocortical PSD, based on Western blot analysis using specific anti-PTP1D antibodies. In addition, NR2B was co-immunoprecipitated with PTP1D using anti-NR2B antibodies or anti-PTP1D antibodies, indicating physical association of the subunit with PTP1D. Moreover, treatment of the purified PSD with BDNF for 5 min elicited a two-fold increase in the association of NR2B with PTP1D. The BDNF action appeared to be specific, since nerve growth factor, another member of the neurotrophin gene family, did not alter the association. Finally, an overlay assay revealed that BDNF caused a two-fold increase in binding of blotted PSD NR2B proteins to PTP1D-SH2 domains, revealing molecular mechanisms mediating the PTP1D-NR2B binding. Taken together, our results raise the possibility that PTP1D participates in BDNF-mediated NR2B signaling cascades at the postsynaptic site, thereby regulating synaptic plasticity.

Animals↗
PubMed1999

Structural determinants for recognition and translocation by the anandamide transporter.

The biological actions of anandamide (arachidonylethanolamide), an endogenous cannabinoid lipid, are terminated by a two-step inactivation process consisting of carrier-mediated uptake and intracellular hydrolysis. Anandamide uptake in neurons and astrocytes is mediated by a high-affinity, Na+-independent transporter that is selectively inhibited by N-(4-hydroxyphenyl)-arachidonamide (AM404). In the present study, we examined the structural determinants governing recognition and translocation of substrates by the anandamide transporter constitutively expressed in a human astrocytoma cell line. Competition experiments with a select group of analogs suggest that substrate recognition by the transporter is favored by a polar nonionizable head group of defined stereochemical configuration containing a hydroxyl moiety at its distal end. The secondary carboxamide group interacts favorably with the transporter, but may be replaced with either a tertiary amide or an ester, suggesting that it may serve as hydrogen acceptor. Thus, 2-arachidonylglycerol, a putative endogenous cannabinoid ester, also may serve as a substrate for the transporter. Substrate recognition requires the presence of at least one cis double bond situated at the middle of the fatty acid carbon chain, indicating a preference for ligands whose hydrophobic tail can adopt a bent U-shaped conformation. On the other hand, uptake experiments with radioactively labeled substrates show that no fewer than four cis nonconjugated double bonds are required for optimal translocation across the cell membrane, suggesting that substrates are transported in a folded hairpin conformation. These results outline the general structural requisites for anandamide transport and may assist in the development of selective inhibitors with potential clinical applications.

Arachidonic Acids↗
PubMed1999

Growth/cell cycle regulation of Sp1 phosphorylation.

Sp1 sites can mediate growth/cell cycle induction of dihydrofolate reductase in late G1 (Jensen, D. E., Black, A. R. Swick, A. G., and Azizkhan, J. C. (1997) J. Cell. Biochem. 67, 24-31). To investigate mechanisms underlying this induction, effects of serum stimulation on regulation of Sp1 were examined. In Balb/c 3T3 cells, serum stimulation did not affect Sp1 synthesis or the relative binding of Sp1 family members to DNA; however, it did result in a rapid, approximately 2-fold increase in Sp1 levels and an approximately 3-fold increase in specific Sp1 phosphorylation in mid-G1. In normal human diploid fibroblasts, serum stimulation also increased Sp1 phosphorylation in mid-G1 but did not affect Sp1 levels. Therefore, Sp1 phosphorylation is regulated in a growth/cell cycle-dependent manner which correlates temporally with induction of dihydrofolate reductase transcription. Further studies revealed a kinase activity specifically associated with Sp1 in a growth-regulated manner. This activity is distinct from purified kinases previously shown to phosphorylate Sp1 in vitro and phosphorylates Sp1 between amino acids 612 and 678 in its C terminus, a region also phosphorylated in mid-G1 in vivo. Therefore, this study indicates that phosphorylation of the C terminus of Sp1 may play a role in the cell cycle regulation of its transcriptional activity.

3T3 Cells↗
PubMed1999

pH-dependent secondary conformation of bovine lens alpha-crystallin: ATR infrared spectroscopic study with second-derivative analysis.

BACKGROUND: In order to simulate the usage of different formulations of ophthalmic solution, the protein conformational changes of lens alpha-crystallin in buffer solutions of different pH were investigated. METHODS: The secondary structure of bovine lens alpha-crystallin in different Mcllvaine buffer solutions (pH 2.2, 4.0, 6.0, 7.2 and 8.0) was determined by attenuated total reflection (ATR)/Fourier transform infrared (FT-IR) spectrometry with second-derivative technique. The turbidity of alpha-crystallin in different buffer solutions was observed. RESULTS AND CONCLUSION: The results indicate that alpha-crystallin exists mainly in beta-sheet structure at 1627-1637 cm-1. The conformational components of alpha-crystallin may be closely similar in pH 7.2 buffer solution and in pH 8.0 buffer solution. Once alpha-crystallin dissolved in pH 6.0 and 4.0 buffer solution, the appearance of a component at 1618 or 1620 cm-1, associated with the presence of intermolecular beta-sheet structure or beta-turn structure or amino acid side chains, implied the denaturation of alpha-crystallin, which was even more marked in pH 4.0 buffer solution. Due to the effect of dissociation and stability of alpha-crystallin in pH 2.2 buffer solution, the secondary structure of the intact alpha-crystallin was difficult to evaluate. This study demonstrates that different pH can vary secondary conformational structure of alpha-crystallin, particularly if the pH is below 6.0. This suggests that the secondary structure of alpha-crystallin in buffer solution exhibits pH-dependent characteristics.

Acids↗
PubMed1999

Cannabinoid receptor and WIN-55,212-2-stimulated [35S]GTPgammaS binding and cannabinoid receptor mRNA levels in several brain structures of adult male rats chronically exposed to R-methanandamide.

We and others have recently demonstrated that the pharmacological tolerance observed after prolonged exposure to plant and synthetic cannabinoids in adult individuals seems to have a pharmacodynamic basis, based on the observed down-regulation of cannabinoid receptors in the brain of cannabinoid-tolerant rats. However, we were unable to elicit a similar receptor down-regulation after a chronic exposure to anandamide, the first discovered endogenous cannabinoid, possibly because of its rapid metabolic breakdown in arachidonic acid and ethanolamine. The present study was designed to progress in these previous studies, by using R-methanandamide, a more stable analog, instead anandamide. In addition, we examined not only cannabinoid receptor binding, but also WIN-55,212-2-stimulated [35S]-GTPgammaS binding, by autoradiography, and cannabinoid receptor mRNA levels, by in situ hybridization. Results were as follows. The daily administration of R-methanandamide for a period of five days produced decreases in cannabinoid receptor binding in the lateral caudate-putamen, cerebellum, entopeduncular nucleus and substantia nigra. The remaining areas, the medial caudate-putamen, globus pallidus, cerebral cortex (layers I and VI), hippocampus (dentate gyrus and Ammon's horn) and several limbic structures (nucleus accumbens, septum nuclei and basolateral amygdaloid nucleus), exhibited no changes in cannabinoid receptor binding. Similarly, the levels of cannabinoid receptor mRNA expression decreased in the lateral and medial caudate-putamen and in the CA1 and CA2 subfields of the Ammon's horn in the hippocampus after the chronic exposure to R-methanandamide, whereas the remaining areas showed no changes. WIN-55,212-2-stimulated [35S]-GTPgammaS binding did not change in the lateral caudate-putamen, cerebral cortex (layer I), septum nuclei and hippocampal structures (dentate gyrus and Ammon's horn) of animals chronically exposed to R-methanandamide, whereas a certain trend to decrease could be observed in the substantia nigra and deep layer (VI) of the cerebral cortex in these animals. In summary, as reported for other cannabinoid receptor agonists, the prolonged exposure of rats to R-methanandamide, a more stable analog of anandamide, was able to produce cannabinoid receptor-related changes in contrast with the absence of changes observed early with the metabolically labile anandamide. The observed changes exhibited an evident regional pattern with areas, such as basal ganglia, cerebellum and hippocampus, responding to chronic R-methanandamide treatment while regions, such as the cerebral cortex and limbic nuclei, not responding.

Animals↗
PubMed1999

Analysis of aberrant transcription of TSG101 in hepatocellular carcinomas.

A variety of studies suggest that tumour suppressor loci on chromosome 11p are important in various forms of human neoplasia. Recently, a gene located at the chromosome 11p 15.1-15.2 region called TSG101 was discovered and proposed as a candidate tumour suppressor gene in breast cancers. We evaluated the TSG101 gene in a panel of liver cancer cell lines and paired tumours and non-malignant tissues. In this study, four of the seven (57%) cell lines, eight of the 18 (44%) tumours and four of the 18 (22%) non-malignant liver tissues exhibited aberrant TSG101 transcripts by nested reverse transcription-polymerase chain reaction (RT-PCR) analysis. However, a normal-sized transcript without sequence abnormalities verified by single-stranded conformation polymorphism (SSCP) analysis was expressed at robust levels in all the cell lines and most of the tissue samples tested. In addition, Southern blot analysis could identify no genomic abnormalities of the gene. Our results suggest either that the TSG101 gene may not be involved in hepatocarcinogenesis or that it plays a role in the development and/or progress of hepatocellular carcinomas through an unusual mechanism.

Adult↗
PubMed1999

UV-B-induced secondary conformational changes in lens alpha-crystallin.

The changes in turbidity and protein secondary structure of alpha-crystallin after a 72 h UV-B (302 nm) irradiation in aqueous solution have been determined by UV spectrophotometry and Fourier transform infrared (FT-IR) microspectroscopy with reflection mode. The relative transmission of alpha-crystallin aqueous solution gradually decreases with the exposure time, indicating that the transparent alpha-crystallin aqueous solution becomes opaque with prolonged UV-B irradiation. The turbidity induced by UV-B shows first-order kinetics due to the photo-induced aggregation. The modification of the secondary structure of the alpha-crystallin molecule in aqueous solution caused by this aggregation might enhance the alpha-helix and beta-turn structures from 8.14 to 14.92% and from 24.46 to 35.54%, respectively; reduce the beta-sheet structure from 60.20% to 43.77%; and leave the random coil structure almost unaltered. The secondary conformation of alpha-crystallin changes gradually but evidently with its increase of turbidity during UV-B exposure.

Animals↗
PubMed1999

Double cartilage block ossiculoplasty in chronic ear surgery.

OBJECTIVES/HYPOTHESIS: Multiple techniques of ossicular reconstruction have been advocated for hearing rehabilitation in the setting of chronic otitis media No single method can adequately address the clinical spectrum of disease severity. In the situation of a severely diseased ear requiring a canal wall down (CWD) mastoidectomy in the presence of an intact stapes superstructure, the authors have employed a double cartilage block (DCB) ossiculoplasty. The technique and short-term results are reviewed. STUDY DESIGN: Retrospective chart review in a tertiary referral otologic practice. METHODS: Twenty-three patients underwent a CWD tympanomastoidectomy with DCB ossiculoplasty. Ages ranged from 6 to 85 years (mean, 36.1 y). The majority of ears were actively draining at the time of surgery (83%) and most procedures were revisions of prior mastoidectomies (74%). Audiometric data (mean postoperative follow-up, 19.5 mo) were calculated according to 1995 American Academy of Otolaryngology-Head and Neck Surgery guidelines. RESULTS: Audiometric results were available in 20 patients. The mean air-bone gap (ABG) was 23.8 dB after surgery. Closure of the ABG to within 20 dB was achieved in 10 of 20 patients (50%). No cases of DCB extrusion have occurred to date. CONCLUSIONS: The DCB represents an excellent alternative to biocompatible prostheses for ossicular reconstruction in the setting of severe chronic ear disease. As with all methods of ossiculoplasty, long-term follow-up will be necessary to determine if this technique remains stable in the hostile environment in which it has been employed.

Adolescent↗
PubMed1999

Optimal configuration of multiple-focused ultrasound transducers for external hyperthermia.

External ultrasound hyperthermia is considered to be a very flexible modality for heating deep-seated tumors owing to its penetration and focusing ability. However, using this flexibility requires that many complicated, interacting decisions be made to obtain optimal treatment. This paper presents the feasibility of arranging multiple-focused ultrasound transducers to produce an appropriate heating pattern for a specific treatment, based on the optimal scan parameters obtained from an optimization algorithm. The variable scan parameters of the heating system optimized are the transducer tilt and rotation angles, focal depth, scan radius, and output acoustical power. After obtaining the optimal scan parameters, multiple transducers are systematically arranged according to these scan parameters. Three-dimensional ultrasound power deposition and temperature distribution for a specific treatment are calculated for this multiple ultrasound transducer system. A more uniform temperature distribution in the treatment region for a large, highly perfused tumor can be achieved by scanning the system with respect to the central scan axis and/or swinging the transducers inwards and outwards. The maximum heating depth of focused ultrasound transducers used in this heating system is also studied. Simulation results demonstrate that the optimal arrangement of this multiple-focused ultrasound transducer system is highly promising for heating deep, large, and highly perfused tumors.

Algorithms↗
PubMed1999

Subtalar arthrodesis for late sequelae of calcaneal fractures: fusion in situ versus fusion with sliding corrective osteotomy.

Primary subtalar arthritis is not common. In most cases, it is the late sequela of intra-articular calcaneal fracture. Subtalar arthrodesis is mostly used for the treatment of traumatic subtalar arthritis in our clinics. We have compared our early cases of in-situ subtalar fusion with our recent cases of fusion with sliding corrective osteotomy in this clinical report. From 1989 to 1992, 15 feet of 13 patients were treated with subtalar arthrodeses for subtalar arthritis caused by malunion of calcaneal fractures. Fusion in situ was done by Ollier's approach, and resection of bony protrusion was done if there was lateral entrapment syndrome. From 1992 to 1995, 13 feet of 12 patients also received subtalar arthrodeses to salvage their calcaneal fractures, but the subtalar fusion was done by wide lateral approach, calcaneal sliding corrective osteotomy, and sometimes (11 of 13 feet) with Achilles tendon lengthening to restore the calcaneal height and width. Patients of both groups experienced obvious clinical improvement in subtalar pain relief, but there was no difference with walking distance, running, or jumping. The group undergoing fusion with sliding corrective osteotomy was more satisfied with regard to cosmetic results and shoe wear. The overall satisfactory rate in the group who underwent fusion with sliding corrective osteotomy (92%) was superior to the group who underwent fusion in situ (77%). Though our method of sliding corrective osteotomy does not provide much improvement to the talus declination angle, it is suitable for those patients with a "banana"-shaped calcaneus malunion. If the patient has prominent anterior ankle pain caused by tibiotalar impingement, we believe that a distraction subtalar arthrodesis would be more appropriate.

Adult↗
PubMed1999

pH-dependent secondary conformation of the peptide hormone leptin in different buffer solutions.

The secondary structure of leptin in each different pH buffer solution (pH 5.35, 6.75, 7.58 and 8.45) was first determined by attenuated total reflection (ATR)/Fourier transform infrared (FT-IR) spectrometer with second-derivative, Fourier self-deconvolution and band curve-fitting methods to quantitatively estimate the secondary structure of leptin. The results indicate that pH induced more stretching vibration of CH2 and bending vibration of C-H and/or symmetric stretching of carboxylate of leptin structure in higher pH buffer solution than in lower pH buffer solution. Moreover, the band area of amide I for leptin in the higher pH buffer solution markedly enlarged, suggesting the amide I contour of leptin was very sensitive to pH to alter the secondary conformation of leptin structure. The structural component and composition of amide I band for leptin in both pH 6.75 and pH 7.58 buffer solutions were similar and had 50-52% helical structure including alpha-helix at 1654 cm-1 and 3(10)-helical structure at 1659-1667 cm-1 and 1640 cm-1. Although the secondary structure of leptin in pH 5.35 and 8.45 buffer solutions were also similar, a different structural information was obtained.

Animals↗