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Biomedical subjects

C Y Su

Publications and source records attributed to C Y Su.

At least 37 records · Page 2Linked to original sources
PubMed2000

Concentration of vascular endothelial growth factor in the subretinal fluid of retinal detachment.

The purpose of this study was to investigate the release of vascular endothelial growth factor (VEGF) within the subretinal fluid in eyes with retinal detachment. Subretinal fluid was collected from patients with retinal detachment undergoing surgery for scleral buckling. Serum samples were also collected. The concentration of VEGF in the subretinal fluid and serum was investigated by enzyme-linked immunospecific assay. The average concentration of VEGF in serum samples was 168 +/- 153 pg/ml (mean +/- standard deviation). It was lower than the VEGF concentration in the subretinal fluid (485 +/- 570 pg/ml) in the same 18 patients with retinal detachment (p < 0.05). The average concentration of VEGF was 355 +/- 373 pg/ml in 31 samples of the subretinal fluid collected from simple rhegmatogenous retinal detachment. It was lower than the average concentration of 901 +/- 385 pg/ml in 8 samples of the subretinal fluid from retinal detachment with proliferative vitreoretinopathy (p < 0.05). The results suggest that the relative retinal ischemia in detached retina increases the release of VEGF into the subretinal space. Also, the concentration of VEGF within the subretinal fluid in proliferative vitreoretinopathy was higher than in simple rhegmatogenous retinal detachment.

Adolescent↗
PubMed2000

Diagnostic usefulness of telomerase activity in nasopharyngeal carcinoma.

Telomeres are specialized structures at the ends of eukaryotic chromosomes which are composed of simple repetitive G-rich hexameric sequences. Activation of telomerase, a ribonucleoprotein that synthesizes telomeric DNA, is found in most malignant tumors. However, little data is available concerning the correlation between telomerase activity and NPC (nasopharyngeal carcinoma). In this study, telomerase activation was determined using the TRAP (telomerase repeat amplification protocol) assay in 62 nasopharyngeal biopsies (25 NPC, 25 non-malignant nasopharyngeal lymphoid tissues, 12 post-irradiated nasopharyngeal tissues). The results showed that strong telomerase activity was present in both NPC and non-malignant nasopharyngeal biopsies. Post-irradiated nasopharyngeal samples had a significantly lower telomerase activity than NPC and non-malignant nasopharyngeal lymphoid tissues. It is well known that nasopharyngeal tissue is infiltrated by numerous lymphocytes, which might retain telomerase activity. Therefore, the finding that the telomerase activation was lowest in post-irradiated nasopharyngeal tissues is reasonable because of the destruction of activated lymphocytes and NPC by radiation. NPC biopsies with positive lymph node involvement exhibited higher levels of telomerase compared to those without lymph node involvement. Our data indicate a positive association between telomerase activity and tumor potential for lymphatic spreading in limited local tumors. In addition, telomerase activity may be useful as a diagnostic marker in the detection of tumor cells in recurrent NPC, but not in primary NPC.

Adolescent↗
PubMed2000

Regulation of endothelial heme oxygenase activity during hypoxia is dependent on chelatable iron.

The regulation of heme oxygenase (HO) activity and its dependence on iron was studied in bovine aortic endothelial cells (BAEC) subjected to hypoxia-reoxygenation (H/R). HO activity was induced by hypoxia (10 h) and continued to increase during the reoxygenation phase. HO-1 protein levels were strongly induced by hypoxia from undetectable levels and remained elevated at least 8 h postreoxygenation. Addition of the Fe(3+) chelator desferrioxamine mesylate (DFO) or the Fe(2+) chelator o-phenanthroline during hypoxia alone or during the entire H/R period inhibited the induction of HO activity and HO-1 protein levels. However, DFO had no effect and o-phenanthroline had a partial inhibitory effect on HO activity and protein levels when added only during reoxygenation. Loading of BAEC with Fe(3+) enhanced the activation of the HO-1 gene by H/R, whereas loading with L-aminolevulinic acid, which stimulates heme synthesis, had little effect. These results suggest that chelatable iron participates in regulating HO expression during hypoxia.

Acetylcysteine↗
PubMed2000

A low temperature plastic anterior encased ankle foot orthosis: construction and preliminary clinical results.

There are two basic plastic AFO designs, either posterior or anterior design, used to resolve spastic ankle and foot problems. The alternative designs of plastic AFOs, of either anterior or posterior design, may include modification with different shapes and materials. This paper describes a new low temperature plastic anterior AFO design, named as anterior encased ankle foot orthosis (AEAFO), which is useful to correct typical hemiplegic gait problems. It can be easily and quickly fabricated, as well as readjusted in OT clinics. The AEAFO has demonstrated an excellent effect on controlling foot inversion and ankle plantar flexion that are commonly encountered by stroke and head injury patients during ambulation. The preliminary effects, strength and durability of AEAFO in clinical applications are most satisfactory.

Ankle↗
PubMed2000

[Studies on metabolite of beta-elemene in rat bile].

AIM: To study the metabolite of beta-elemene in the bile of rat. METHODS: After i.v. 100 mg.kg-1 beta-elemene, the metabolite in rat bile was extracted by ether. Mass spectrometry, nuclear magnetic resonance, infrared spectrometry and ultraviolet spectrometry were used to analyze the metabolite of i.v. beta-elemene in rat bile. RESULTS: It was confirmed by nuclear magnetic resonance that the methyl of No. 11 carbon connecting with No. 10 carbon of a metabolite in rat bile was oxidized to be aldehyde. The molecular weight of the metabolite was 218 which detected by mass spectrometry. Infrared spectrometry and ultraviolet spectrometry proved that the aldehyde existed in the metabolite. The structure of the metabolite in bile of rat was identified, that was 1-methyl-1-ethenyl-2-isopropenyl-4-isopropenyl aldehydohexamethylene. CONCLUSION: The biotransformation of beta-elemene exists in vivo.

Animals↗
PubMed2000

[Pharmacokinetics and disposition of beta-elemene in rats].

AIM: To study the pharmacokinetics, absorption, distribution and excretion of beta-elemene obtained from the roots and stems of Curcuma wenynjin Y. H Chen et C. Ling. in rats. METHODS: A GC method for isolation and determination of beta-elemene in biological specimens was used. RESULTS: After a single i.v. dose to rats, the plasma concentration-time course of beta-elemene fitted well to a two-compartment open model. With regard to i.p. administration of a single dose of 100 mg.kg-1 to rats, the absorption of the drug was rapid. Elimination of the drug from plasma was found to be in accord with linear kinetics, whereas the elimination half-lives were longer than that of i.v. administration. Only small amount of unchanged beta-elemene was excreted in urine, feces and bile after i.v. and i.p. administration. Plasma protein binding ratio was obtained from two different levels of beta-elemene, 97.7% from 60 micrograms.mL-1 and 96.5% from 100 micrograms.mL-1. CONCLUSION: beta-elemene was eliminated at a rapid rate and distributed widely in the body. The protein binding was found to be high. Unchanged beta-elemene excreted via urine, feces and bile were very few.

Animals↗
PubMed1999

Constitutive hsp70 attenuates hydrogen peroxide-induced membrane lipid peroxidation.

Thermal pretreatment improves cardiac recovery from subsequent ischemia/reperfusion. Induction of heat shock proteins (hsps) may contribute to this protection. We have demonstrated that augmentation of the constitutive hsp70 (hsc70) in H9c2 heart myoblasts promotes oxidative resistance. We employed a model oxidant to explore potential target(s) of protection by hsc70. Upon exposure to 54 microM of hydrogen peroxide (H(2)O(2)), hsc70-overexpressing cells exhibited a lower lipid peroxidation than the sham-transfected control. Constitutive hsc70 overexpression, however, did not protect against H(2)O(2)-induced depletion of ATP and glutathione (GSH). Lipid protection also occurred in cells preconditioned at 39 degrees C (selectively induces hsc70) during H(2)O(2) exposure. Interestingly, the protection conferred by hsc70 was comparable in magnitude to that provided by alpha-tocopherol, and was followed with a reduced release of lactate dehydrogenase and a unaltered calcium uptake during H(2)O(2) challenge. Collectively, our observations suggest that hsc70 may preserve membrane function via attenuation of lipid peroxidation during oxidative insult.

Animals↗
PubMed1999

Differential effects of ganodermic acid S on the thromboxane A2-signaling pathways in human platelets.

Ganodermic acid S (GAS) [lanosta-7,9(11),24-triene-3beta,15alpha-diacetoxy-26-oic acid], isolated from the Chinese medicinal fungus Ganoderma lucidum (Fr.) Karst (Polyporaceae), exerted a concentration-dependent inhibition on the response of human gel-filtered platelets (GFP) to U46619 (9,11-dideoxy-9alpha,11alpha-methanoepoxyprostaglandin F2alpha), a thromboxane (TX) A2 mimetic. GAS at 2 microM inhibited 50% of cell aggregation. GAS at 7.5 microM inhibited 80% of Ca2+ mobilization, 40% of phosphorylation of myosin light chain and pleckstrin, 80% of alpha-granule secretion, and over 95% of aggregation. GAS also strongly inhibited U46619-induced diacylglycerol formation, arachidonic acid release, and TXB2 formation. An immunoblotting study of protein-tyrosine phosphorylation showed that GAS inhibited the formation of phosphotyrosine proteins at the steps involving the engagement of integrin alphaIIbbeta3 and aggregation. However, GAS did not inhibit U46619-induced platelet shape change or the inhibitory effect of U46619 on the prostaglandin E1-evoked cyclic AMP level in GFP. It is concluded that GAS inhibits platelet response to TXA2 on the receptor-Gq-phospholipase Cbeta1 pathway, but not on the receptor-G1 pathway.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1999

Novel strategy yields candidate Gsh-1 homeobox gene targets using hypothalamus progenitor cell lines.

We describe the successful application of a strategy that potentially provides for an efficient and universal screen for downstream gene targets. We used the promoter of the Gsh-1 homeobox gene to drive expression of the SV40 T-antigen gene in transgenic mice. We have previously shown that the Gsh-1 homeobox gene is expressed in discrete domains of the ganglionic eminences, diencephalon, and hindbrain during brain development. Gsh-1-SV40 T transgenic mice showed cellular hyperplasia in regions of the brain coincident with Gsh-1 expression. The Gsh-1-SV40 T transgene was introduced, by breeding, into Gsh-1 homozygous mutant mice, and Gsh-1 -/- cell lines were made. Clonal cell lines were generated and analyzed by Northern blot hybridizations and Affymetrix GeneChip probe arrays to determine gene expression profiles. The results indicate that the cell lines remain representative of early developmental stages. Further, immunocytochemistry showed uniformly high levels of nestin expression, typical of central nervous system progenitor cells, and the absence of terminal differentiation markers of neuronal cells. One clonal cell line, No. 14, was then stably transfected with a tet-inducible Gsh-1 expression construct and subcloned. The starting clone 14, together with the uninduced and induced subclones, provided cell populations with varying levels of Gsh-1 expression. Differential display and Affymetrix GeneChip probe arrays were then used to identify transcript differences that represent candidate Gsh-1 target genes. Of particular interest, the drm and gas1 genes, which repress cell proliferation, were observed to be activated in Gsh-1-expressing cells. These observations support models predicting that homeobox genes function in the regulation of cell proliferation.

Animals↗
PubMed1999

Computed tomography findings of bony regeneration after radiotherapy for nasopharyngeal carcinoma with skull base destruction: implications for local control.

PURPOSE: To evaluate the response of bony destruction (BD) of the skull base following radiotherapy in nasopharyngeal carcinoma (NPC) and investigate the implications of bony regeneration (BR) on local control and its related factors. METHODS AND MATERIALS: Ninety patients with NPC with skull base destruction clearly demonstrated on computed tomography (CT) were reviewed. These patients have completed the prescribed treatment and received regular CT follow-up. A total of 338 sets of CT images of the head and neck were reviewed. The tumor response and the appearance of BR in the previous destructive part of the skull base were recorded and analyzed. The tumor response was divided into complete, partial, or no response. BR was defined as recalcification or sclerotic change with partial or complete healing in the previous osteolytic bony defect. Local failure was confirmed either by pathological or merely by imaging studies showing progression of tumor in consecutive radiological pictures. RESULTS: The distribution of specific sites of bony destruction (BD) in these patients included the sphenoid bone (68%), paracavernous sinus area (48%), petrous apex (47%), clivus (44%), pterygoid plates (20%), and others (7%). The CT showed 57 patients (63%) had BR. All were observed within 1 year after treatment. Sixty-two patients (69%) had complete tumor response after treatment. Analyzed by logistic regression method, tumor response after treatment was found to have a statistically significant correlation with BR (p = 0.0004). Most BR (55/57) was demonstrated in patients with complete tumor response. The 3-year actuarial local control rate was 54 % in these patients. The local control was quite different in the comparison of patients with BR versus those with persistent BD (77% vs. 21%, p < 0.0001). Multivariate analysis showed that patients with complete tumor response or with BR on imaging had statistically better local control than those without either of the two findings (p < 0.05). CONCLUSION: Appearance of BR at previous destructive skull base following radiotherapy for NPC patients could be clearly demonstrated on CT. Bony regeneration significantly correlated with treatment response and local control. Although the underlying significance of BR was unknown, to predict the outcome after treatment, the appearance of BR shown on CT may imply the complete eradication of tumor in this area.

Adolescent↗
PubMed1999

Predominant inhibition of ganodermic acid S on the thromboxane A2-dependent pathway in human platelets response to collagen.

Ganodermic acid S (GAS), a membrane acting agent, exerts multiple effects on human platelet function (C.N. Wang et al. (1991) Biochem. J. 277, 189-197). The study reported how GAS affected the response of human gel-filtered platelets (GFP) to collagen. The agent inhibited cell aggregation by prolonging lag and shape change periods and decreasing the initial cell aggregation rate. However, the inhibitory efficiency was less than its inhibition on GFP response to U46619, a thromboxane (TX) A2 mimetic. In the agent-effect on biochemical events, GAS effectively inhibited Ca2+ mobilization, phosphorylation of myosin light chain, dense granule secretion and TXB2 generation. The inhibitions might originate from blocking Ca2+ mobilization of the TXA2-dependent pathway. GAS partially decreased the phosphorylation of most phosphotyrosine proteins from early activation to the integrin alphaIIbbeta3-regulated steps. The agent did not affect the phosphorylation of three proteins at the steps regulated by integrin alphaIIbbeta3. The results suggest that GAS inhibits the collagen response predominantly on the TXA2-dependent signaling, and the tyrosine kinase-dependent pathway in collagen response plays a major role in aggregation.

Blood Platelets↗
PubMed1999

Induction of heat-shock protein 72 in rat skeletal muscle does not increase tolerance to ischemia-reperfusion injury.

Ischemia-reperfusion injury is implicated in the failure of free flap and replant surgeries and is associated with the pathogenesis of a wide variety of clinical diseases including stroke, myocardial infarction, spinal injury, and compartment syndromes. We used a skeletal muscle flap model to test if the induction of heat-shock protein 72 (HSP72) by mild hyperthermia provides tolerance against ischemia-reperfusion injury. Immunocytochemistry and Western blot analysis verified increased production of HSP72 in the gracilis muscle of globally heated rats. Neutrophil accumulation in the microvasculature and postischemic muscle survival after ischemia-reperfusion were unaltered by preischemic hyperthermia, indicating HSP72 induction is not sufficient to provide resistance against severe injury in skeletal muscle.

Adaptation, Physiological↗
PubMed1999

Scanning electron microscopy observation of vascularization around hydroxyapatite using vascular corrosion casts.

An intimate relationship exists between the regenerative response of the vascular and osseous elements following hydroxyapatite (HA) implantation. In order to fully comprehend the 3-dimensional vascular architecture around HA, dense HA particles were implanted into the tibiae of dogs. Following healing periods of 2 weeks, 1 month, and 3 months, the tibiae were prepared by the corrosion cast technique. Under scanning electron microscopy (SEM) observation, the characteristic vascular morphology of the HA-implanted cavity was successfully demonstrated. The initial vascularization began in the form of loose sinusoidal capillaries. Many sinusoids formed a complex network by anastomosing with each other. The newly formed vessels extended centripetally from the peripheral cavity wall and from the periosteal surface. Under greater magnification, the tapered vascular sprouting was shown to project into the space that was previously occupied by an HA particle. The presence of vascular sprouting is clearly an important indicator of angiogenesis. Increasing vascularization was demonstrated with time. The presence of vessels in the Haversian's canal indicated the more established vascularization. Almost full vascularization of the HA-implanted cavity was seen 3 months after implantation. The vascular organizational layout of the cavity was also clearly shown in the fractured transverse-sectioned sample. In the control without HA implantation, the central region of the cavity showed a hollow pattern in the initial stage. The vascularization looked like it was collapsing and not fully filling the cavity. However, remarkable differences of the final vascular pattern could not be found between the study and control group after 3-month implantation. The study provides the time-lapsed 3-dimensional vascular changes of the HA-implanted cavity, as well as the value of the corrosion cast technique in examining the bony circulation.

Animals↗
PubMed1999

A physiologically relevant hyperthermia selectively activates constitutive hsp70 in H9c2 cardiac myoblasts and confers oxidative protection.

Whole body hyperthermia (42-43 degrees C for 15-20 min) elicits the formation of heat shock proteins (hsps) and improves cardiac recovery from subsequent ischemia/reperfusion. However, the beneficial effects of this response are compromised by initial tissue injury, which limits its clinical applicability. Using a simplified myocardial model (rat heart-derived H9c2 myoblasts) a hypothesis was tested that chronic, mild hyperthermia is as effective as acute heat shock in inducing the heat shock response. Our results indicate that 39 degrees C pre-conditioning evoked thermotolerance and oxidative resistance, but caused no detectable adverse effects. An improved survival after hydrogen peroxide (H2O2) exposure (40-54 microm for 3 h) was first observed in cells pre-conditioned at 39 degrees C for 24 h. As the duration of thermal pre-incubation increased, cells became more resistant than the control (37 degrees C) to a greater toxicity of H2O2(68 microm). An optimal oxidative protection developed by;4 days at 39 degrees C and this persisted for as long as the cells were incubated at this temperature. Three hsps are known to modulate cellular antioxidant defenses: the constitutive-hsp70 (hsc70), its inducible counterpart (hsp70), and hsp27. The authors found that mild hyperthermia selectively induced only hsc70, which demonstrates a lower temperature threshold for activation of hsc70. The initial protection against the milder H2O2challenge correlated with a homogenous distribution of pre-existing hsc70. The subsequent optimal protection was associated with an identical distribution pattern and a moderate increase of hsc70. These observations suggest that mild hyperthermia induces a beneficial adaptive response, in which hsc70 plays a critical role.

Adaptation, Physiological↗
PubMed1999

Three-dimensional imaging of the speaking shunt in patients with near-total laryngectomy.

OBJECTIVES: Near-total laryngectomy with creation of a speaking shunt is generally considered suitable treatment for most T3 and some T4 laryngopharyngeal cancers. In some patients, poor speech production by the shunt can be problematic and usually means that a shunt lumen is stenotic or too small. Conventional axial computed tomography (CT) of the neck is of little value in predicting the shunt function and the patency of the shunt lumen. Such defect, however, can be better overcome if the spiral CT is used. STUDY DESIGN: This study was designed to evaluate the dynamic speaking shunt by spiral CT and a three-dimensional (3-D) imaging model of the upper airway in 59 near-total laryngectomies. METHODS: During scanning, the patients were asked to make a single, 20-second phonation. A high-quality 3-D surface model was then rendered at an independent workstation. The 3-D model took on the appearance of the speaking shunt which could serve as a tracheopharyngeal fistulography. RESULTS: 3-D reconstruction of the images could clearly demonstrate the dynamic anatomy and patency of the speaking shunt. We found the 3-D model to be of diagnostic value, particularly in the near-total laryngectomy patients with stenotic shunts. The most common site of stenosis was at the top portion of the shunt. CONCLUSION: The 3-D image findings of the shunts significantly improved the assessment and therapies of the patients undergoing revision surgeries of the shunt stenoses.

Adult↗
PubMed1999

A new transnasal approach to endoscopic marsupialization of the nasolabial cyst.

OBJECTIVE: Nasolabial cyst is a mucus-secreting, nonodontogenic cyst in the nasofacial area. It is usually situated behind the ala nasi, extending backward beneath the nasal floor into the inferior meatus and forward into the labio-gingival sulcus behind the upper lip. Patients with nasolabial cysts generally undergo surgical removal of the cyst via a transoral sublabial approach. This article reports a simple, less invasive surgical procedure for the treatment of nasolabial cysts. STUDY DESIGN: A transnasal endoscopic marsupialization method was designed to treat patients with nasolabial cysts. From 1996 through 1998, 16 consecutive patients underwent this new surgical procedure. METHODS: With patients under local anesthesia, the roof of the cyst, which was firmly attached to the mucous membrane of the anterior nasal floor, was removed transnasally with a sickle knife and scissors. Under the guidance of a nasoendoscope, the opening of the cyst was widened with bite forceps. Meanwhile, the cut edges of the nasal mucosa and the epithelium lining of the cyst were adequately matched. The nose was then loosely packed. RESULTS: All but 1 of the 15 patients were successfully treated with this technique, and the whole surgical procedure was usually completed within 15 to 20 minutes. Postoperative endoscopic and radiological findings revealed that the cyst was replaced by an air-containing sinus with a persistent opening at the anterior or anterolateral nasal floor. There has been no evidence of mucus accumulation in the newly created sinus or recurrence of the cyst during a mean follow-up of 16 months. CONCLUSIONS: Transnasal endoscopic marsupialization is a simple and effective surgical procedure for treatment of nasolabial cysts.

Adult↗