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Biomedical subjects

C P Lin

Publications and source records attributed to C P Lin.

At least 19 recordsLinked to original sources
PubMed1998

Serine protease activity is essential for thrombin-induced protein synthesis in cultured human dental pulp cells: modulation roles of prostaglandin E2.

Irritations and injuries to the dental pulp usually lead to different degrees of pulpal inflammation. To investigate the roles of thrombin and prostaglandins in the healing and inflammatory processes of dental pulp as well as their effects on pulpal protein synthesis, human dental pulp cell cultures were established and their protein production was measured with or without the presence of exogenous thrombin and prostaglandins. At concentrations of 1-25 U/ml, alpha-thrombin increased the protein synthesis to 1.4-2.3 fold over the vehicle control. On the contrary, 0.1 microg/ml of prostaglandin E1 (PGE1) suppressed protein synthesis by 60%. Prostaglandin E2 (PGE2) also inhibited protein synthesis with an IC50 of 0.4 microg/ml. The stimulatory effects of thrombin (10 U/ml) can be inhibited by antithrombin III (2 U/ml) (a natural thrombin inhibitor) with heparin (2 U/ml), PPACK (D-Phe-Pro-ArgCH2Cl) (20-50 microg/ml) (a serine protease inhibitor), and PGE2 (0.5-1.0 microg/ml). Moreover, TRAP (20-40 microg/ml), a thrombin receptor agonist peptide, also exerted a stimulatory effect (1.21-1.37 fold). In conclusion, thrombin-induced protein synthesis by pulp cells is dependent on proteolytic activity, but not on binding to receptors. Both PGE1 and PGE2 exert suppressive effects on protein synthesis, indicating that interactions between thrombin and prostaglandins are important in regulating the inflammation, repair and regeneration of pulp tissue following injury.

Adult↗
PubMed1997

Effect of antiproliferative flavonoids on ascorbic acid accumulation in human colon adenocarcinoma cells.

Dietary flavonoids were found to be antiproliferative for human colon cancer cells, Caco-2 and HT-29, and rat nontransformed intestinal crypt cells, IEC-6. The antiproliferative potency was found to be structure-dependent. We report here a correlation between the antiproliferative potency of these flavonoids and their ability to inhibit cellular accumulation of ascorbic acid (vitamin C). Caco-2, HT-29 and IEC-6 cells were found to accumulate ascorbic acid in a sodium-dependent fashion although some ascorbic acid may also enter the cells through sodium-independent mechanisms. Flavonoids that have been found to be antiproliferative, quercetin and genistein, inhibited the accumulation of ascorbic acid. The inhibition was dose-dependent and could be observed after as short as 10-min of incubation. The degree of inhibition of accumulation was more during rapid cell division as compared to post-confluency Caco-2 cells. Flavonoids that were found to show little antiproliferative effect, naringenin and catechin, also had little effect on ascorbic acid accumulation. The antiproliferative property of flavonoids could be linked to their ascorbic acid deprivation property.

Animals↗
PubMed1997

Rhenium-188 hydroxyethylidene diphosphonate: a new generator-produced radiotherapeutic drug of potential value for the treatment of bone metastases.

The search for an ideal radioisotope for systemic radiotherapy continues. As a generator-produced radioisotope emitting both beta and gamma rays and having a short physical half-life of 16.9 h, rhenium-188 is a very good potential candidate for systemic radiotherapy. In this study, we labeled hydroxyethylidene diphosphonate (HEDP) with 188Re and analyzed the biodistribution and bone uptake following intravenous injection in rats to assess its potential for clinical use. The rats were injected with approximately 14.8 MBq (0.4 mCi) 188Re-HEDP in a volume of 0.1 ml intravenously and then sacrificed at 1 h, 24 h, or 48 h (four rats at each time). Samples (about 0.1 g) of lung, liver, kidney, spleen, testis, muscle, stool, and bone (thoracic vertebra) were taken and weighed carefully. In addition, a 1-ml sample of blood was drawn from the heart and 1 ml of urine was taken from the urinary bladder immediately after killing. Tissue concentrations were calculated and expressed as percent injected dose per gram or per milliliter (% ID/g or ml). Bone lesions were created in the right tibial bone in three rabbits to calculate the lesion to normal uptake ratio (L/N ratio). The biodistribution data showed that the radioactivity in the bone tissue was as high as 1.877% ID/g at 1 h and that it climbed to 2.017% ID/g at 4 h. The activity level in the kidney was highest at 1 h but declined rapidly throughout the study. The radioactivities in the lung, liver, muscle, spleen, testis, blood, and stool were all lower than 0.3% ID/g at 1 h and also declined rapidly. The biological half-life in bone was the longest (60.86 h). In contrast, the biological half-lives in muscle and blood were short (2.99 h and 6.21 h respectively). The concentrations of radioactivity in muscle, spleen, testis, and stool were quite low throughout the study. Most of the radiotracer was excreted by the urinary system. The L/N ratio was 4.23+/-0.21 in rabbits injected with 188Re-HEDP and 4.25+/-0.23 in those injected with technetium-99m methylene diphosphonate. In conclusion, we would suggest that 188Re-HEDP is a very good potential candidate for the treatment of bone metastases because of the following characteristics: (1) it is generator produced; (2) it has a short half-life; (3) it emits gamma rays suitable for imaging; (4) there is highly selective uptake in the skeletal system and bone lesions; and (5) it has a low non-target uptake and rapid clearance in nonosseous tissue.

Animals↗
PubMed1997

Immunolocalization of interstitial collagenase (MMP-1) and tissue inhibitor of metalloproteinases-1 (TIMP-1) in radicular cysts.

To investigate the mechanisms involved in expansion of radicular cysts, monoclonal antibodies against interstitial collagenase (MMP-1) and tissue inhibitor of metalloproteinases-1 (TIMP-1) were used to localize the sites of MMP-1 and TIMP-1 expression in 30 radicular cysts. Positive MMP-1 staining was detected in the lining epithelium and subepithelial fibroblasts, macrophages, endothelial cells and osteoblasts/osteocytes in all specimens. Positive TIMP-1 staining was identified in osteoblasts/osteocytes and endothelial cells of all specimens, and in the lining epithelium and subepithelial fibrous connective tissue wall of five radicular cysts with an intense inflammatory cell infiltrate. The number and distribution of positive cells for MMP-1 or TIMP-1 varied widely among individual specimens, but strong immunostaining was constantly detected at sites with prominent subepithelial inflammation. Results here support the hypothesis that MMP-1 may play an important role in the expansion of radicular cysts. The absence of TIMP-1 expression in lining epithelium and subepithelial fibroblasts and macrophages in most cases studied indicated that an imbalance between MMP-1 and TIMP-1 production may lead to radicular cyst expansion.

Antibodies, Monoclonal↗
PubMed1997

Clinical experiences of infectious scleral ulceration: a complication of pterygium operation.

AIMS: To report the special clinical manifestations and determine the appropriate management of infectious scleral ulceration. METHODS: A retrospective study was performed on 30 eyes with infectious scleral ulceration. Information was recorded on patients' age, onset and course of disease, pathogenic organism, clinical presentations, methods of diagnosis, treatment, and outcome. RESULTS: 10 cases (33.3%) were accompanied by corneal involvement. Subconjunctival abscess was noted in 16 cases (53.3%). 17 cases (56.7%) gave positive results of pathogen culture and all were Pseudomonas aeruginosa. Two cases had combined bacterial infections and one case was complicated by fungal infection. A total of 26 cases had surgical debridement in this series. Extensive involvement of the sclera with the presence of a 'tunnel lesion' or a 'satellite subconjunctival abscess' were found during debridement. All of the eyeballs involved were salvaged except one. CONCLUSION: The results of this study were contrary to the poor prognosis presented in previous reports. Early and repetitive surgical debridement is believed to be mandatory in the intractable cases to shorten the admission period and to save these eyes.

Aged↗
PubMed1997

Total failure energy of a composite resin bonded to human enamel.

Total failure energy is defined as the energy required to stress a bond to the point of fracture. This study was designed to assess and compare the total failure energy of a resin-enamel bond with conventional tensile and shear bond strengths. A commercially available composite resin was bonded to human enamel surface. During testing, the applied load versus displacement of the load fixture was recorded and analyzed by a data acquisition system. The tensile and shear bond strengths as well as the total failure energies were calculated. The mean tensile bond strength (21.2 MPa) was higher than the mean shear bond strength (11.6 MPa). The mean total energy applied for tensile failure of the bond (2.1 kg.mm) was also higher than that for the shear failure (1.5 kg.mm). There were statistically significant correlations between bond strength and total failure energy. The failure modes of the shear bond test revealed a higher frequency of adhesive failures compared to the tensile bond test. Further, a dramatic difference existed in the cohesive failure mode between tensile (cohesive composite failure) and shear (cohesive enamel failure) tests. The total failure energy, which represents the fracture strength as well as the failure process of a bond, may be considered an appropriate criterion for characterizing the failure of a bond.

Composite Resins↗
PubMed1997

Scanning electron microscopic evaluation of the cleanliness of a new ultrasonic root end preparation.

Recently introduced ultrasonic instrumentation techniques for root end preparation have revolutionized the field of endodontic surgery. The specially designed tips offer improved access to the root end and create more conservative root and preparations while decreasing the amount of retained debris. This study compared the cleanliness of root end preparations made using ultrasonic instrumentation with that of those prepared in a traditional manner using a microhandpiece bur. We used 10 extracted maxillary human premolars and molars. After cleaning, shaping, and obturation of the root canals, a 3 mm root end resection perpendicular to the long axis of the root was performed with a carbide fissure bur. The roots were randomly divided into two groups and root end preparations were made using the two aforementioned techniques. The roots were longitudinally split and sputter-coated with gold for scanning electron microscopic study. Three independent dentists used a standardized grading system to evaluate the cleanliness of the root end preparations. The ultrasonic preparation had significantly less superficial debris and a thinner smear layer than the microhandpiece preparation (p < 0.05). There were no significant differences between the canal and isthmus portions of the root end preparations within each group in either superficial debris or smear layer. This indicates that cleaner surfaces for root end cavities are created using ultrasonic retrotips than using microhandpiece burs.

Dental Pulp Cavity↗
PubMed1997

A new model for in vitro corneal epithelial wound healing study.

A new model for an epithelial wound healing study in pig eyes has been developed in which the excimer laser was used for ablation to create an epithelial wound with precise depth and size. The purpose of this study was to set up an in vitro epithelial wound healing model without photography and defect area measurement. In the study twenty-eight pig eyes received phototherapeutic keratectomy (PTK) with the following diameters: eight at 2.0mm, eight at 1.8 mm, and twelve at 1.5mm. All the wounds were 70 microns in depth. Following PTK, the eyeballs were placed in an incubator, and perfused with TC-199 media by vitreous puncture. TC-199 was then used to rinse eight eyeballs from each group. The remaining four eyes from the 1.5mm group were rinsed with 0.02% Benzalkonium Chloride on an epithelial wound. For the eyes rinsed with TC-199 the average healing time for the 2.0mm group was 31.75 +/- 6.18 hours; the 1.8 mm group was 28.75 +/- 3.85 hours, and the 1.5 mm group was 24.5 +/- 1.77 hours. The corneas rinsed with Benzalkonium Chloride did not heal after 36 hour's observation. Twelve eyeballs without PTK were perfused under the same criteria to evaluate the change of IOP. Following twenty-four hours the IOP range was 15.9 to 20.6mmHg with an average of 19.0mmHg. This study revealed that the healing time decreased as the wound diameter became smaller and the healing was retarded by the drug effect. With this model, the drug influences on corneal epithelial wound healing can be evaluated and the result is revealed in approximately twenty-four hours.

Animals↗
PubMed1997

Influence of rigid gas permeable contact lens solutions on corneal epithelial wound healing.

To determine the effect of RGP contact lens solution on corneal epithelial wound healing, the following solutions including Soaclens, Contopharma GPHCL-S, Boston condition, Bausch & Lomb condition and Duracare were applied on corneal epithelial wounds of enucleated pig eyes to evaluate possible cytotoxicity of RGP solutions. The wounds, created by excimer laser, were 1.5mm in diameter with 70 microns in depth. The eyeballs were maintained in an incubator using a perfusion system. After twenty-four hours, a score from 3 to 0 was given depending on the size of defect from absence of healing to completely healing. The average scores of the epithelial defect in each group are: Soaclens: 0.38 +/- 0.74; GPHCL-S: 0.63 +/- 0.52; Boston condition: 0.38 +/- 0.52; Bausch & Lomb condition: 0.25 +/- 0.46 and Duracare: 2.38 +/- 0.52. Most of the epithelial wounds healed with one exception, the eyeballs which received Duracare still had large defects. The difference of scores between Duracare and other groups are statistically significant. Duracare, which contains benzalkonium chloride, may be responsible for retarded wound healing.

Animals↗
PubMed1997

Alteration of glucose uptake in cultured human corneal endothelial cells grown in high glucose media via cAMP-dependent pathway.

In this study, cultured human corneal endothelial cells were incubated in media containing various concentrations of glucose at 5 mM, 10 mM, and 25 mM for 2 days. Then, the cellular 2-deoxyglucose uptake and cAMP concentration of cultured human corneal endothelial cells were measured. The results indicated that the activity of cellular glucose uptake of nmole/min/mg protein was decreased gradually from 0.18 (5 mM), 0.10 (10 mM), 0.07 (20 mM) to 0.06 (25 mM) after 2 days incubation with a high concentration of glucose. The glucose uptake in insulin-treated human corneal endothelial cells also exhibited a similar declining effect in high glucose media from 0.30 (5 mM), 0.11 (10 mM), 0.08 (20 mM) to 0.05 (25 mM). The cAMP concentration in human corneal endothelial cells was measured in the presence of high glucose media. It was indicated that the cAMP concentrations of pmole/well in both insulin-treated and non-insulin treated cells were also decreased after increasing the glucose concentration in the media from 73 (5 mM) to 20 (25 mM) and 101 (5 mM) respectively. The cAMP concentration in insulin-treated cells was less than in non-insulin treated cells. This decreasing effect was significantly reversed by the addition of 1 mM dibutyryl-cAMP to the cells for 1 hour in both groups. These results suggest that the diabetic state may decrease the 2-deoxyglucose uptake in human corneal endothelial cells via cAMP-dependent pathway.

Animals↗
PubMed1996

The effects of cooling systems on CO2-lased human enamel.

The thermal effects on dentin during CO2 laser irradiation on human enamel were investigated. To simulate the clinical practice, two cooling methods (air and water spray) were applied immediately after laser exposure, whereas one group without cooling was served as control. Three hundred and sixty uniform tooth blocks were obtained from freshly extracted human third molars. Temperature change measurements were made via electrical thermocouple implanted within the tooth block 2 mm away from the enamel surface. Experimental treatments consisted of lasing without cooling, lasing with 0.5-ml/sec water cooling, and lasing with 15-psi air cooling. Our results indicated that (1) both air- and water-cooling groups could reduce temperature elevation significantly; (2) the larger power energy resulted in the higher temperature elevation. In conclusion, for CO2 laser irradiation on human enamel both water- and air-cooling methods may be effective on prevention of thermal damage of pulp.

Air↗
PubMed1996

Using MTT viability assay to test the cytotoxicity of antibiotics and steroid to cultured porcine corneal endothelial cells.

Intracameral injection (ICI) of antibiotics and steroid is an effective method to deliver drugs into eyeballs, and rapidly achieve therapeutic concentrations. The high intraocular concentrations, however, that occur by such injections can harm the corneal endothelium. The MTT assay, MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide], has been used to test cytotoxicity of five antibiotics (including amphotericin-B, colistin-M, sulbenicillin, amikacin, cephradine) and a steroid, betamethasone, to cultured porcine corneal endothelial cells. The third passage of porcine corneal endothelial cells were plated into 96-well microtitration plates for drugs exposure. Cytotoxicities of the six drugs in different concentrations were compared, using exposure time as an independent variable. In its original and 10-fold ICI dose, only amphotericin-B among the six tested drugs showed significant cytotoxicity; the other drugs were considered safe. In a 100-fold ICI dose, amphotericin-B, colistin-M, and sulbenicillin were all toxic. Although a cell culture system utilizing the MTT assay is an in vitro method of testing for drug toxicity to the corneal endothelium, it nevertheless offers the advantages over in vivo methods. It is rapid, convenient, and economical. Large numbers of toxic compounds can be compared simultaneously, so that relative toxicities among different drugs and concentrations can be obtained, and be a guide for determining ICI dose, or as a reference for further in vivo testing.

Animals↗
PubMed1996

Characterization of monoclonal antibody B7, which neutralizes the cytotoxicity of Pseudomonas aeruginosa exotoxin A.

A nontoxic Pseudomonas aeruginosa exotoxin A (PE), which has the carboxyl-terminal 38 amino acid residues of native PE deleted, was used as an antigen to immunize BALB/c mice, which were then challenged with native PE in order to raise monoclonal antibodies (MAbs) that can neutralize PE cytotoxicity. A murine MAb against PE, designated MAb B7, was established. MAb B7 was characterized in terms of its ability to neutralize PE cytotoxicity, epitope mapping, inhibition of PE receptor binding, and influence on cellular processing of PE and ADP-ribosylation activities. We found that MAb B7 could neutralize PE cytotoxicity in cell culture and in BALB/c mice. The epitope recognized by MAb B7 was mapped to the carboxyl-terminal amino acid residues 575 to 595 of PE. Consistent with the results of epitope mapping, MAb B7 did not block PE receptor-binding activity or the cellular processing of PE but strongly inhibited the ADP-ribosylating activity of PE. In addition, MAb B7 retained strong binding to PE even at pH 4.0, indicating that the complex of MAb B7 and PE is stable in the phagolysosome. On the basis of these observations, the neutralization of PE cytotoxicity by MAb B7 could be due to its binding to the carboxyl terminus of PE. As a result, MAb B7 may interfere with the interaction of the carboxyl-end amino acid residues REDLK of PE with cellular factors. However, we could not rule out the possibility that MAb B7 directly blocks the ADP-ribosylation activity of PE in the cytosol.

3T3 Cells↗
PubMed1996

Repair of a giant scleral ulcer with preserved sclera and tissue adhesive.

BACKGROUND AND OBJECTIVE: Infectious scleral ulcer is a rare but severe late complication of pterygium surgery. Scleral grafts may be required in scleral ectasia with uveal exposure, corneal distortion, and severe anterior chamber reaction that are induced by scleral ulcer. The authors report a method for scleral grafting with preserved sclera and tissue adhesive. PATIENTS AND METHODS: Six cases of infectious scleral ulcers were repaired with this method. Preserved sclera was attached to the thinning sclera with tissue adhesive without sutures. The free or rotation conjunctival flap was placed over the graft area and sutured with 10-0 nylon. RESULTS: The six cases repaired by this method showed good results during the follow-up, except for one loss. The only complication was protrusion of the adhesive postoperatively. This protrusion can be easily removed with forceps on an outpatient basis. CONCLUSION: Tissue adhesive with preserved sclera is a useful method for repair of scleral thinning.

Aged↗
PubMed1995

Optical coherence tomography of the human retina.

OBJECTIVE: To demonstrate optical coherence tomography for high-resolution, noninvasive imaging of the human retina. Optical coherence tomography is a new imaging technique analogous to ultrasound B scan that can provide cross-sectional images of the retina with micrometer-scale resolution. DESIGN: Survey optical coherence tomographic examination of the retina, including the macula and optic nerve head in normal human subjects. SETTING: Research laboratory. PARTICIPANTS: Convenience sample of normal human subjects. MAIN OUTCOME MEASURES: Correlation of optical coherence retinal tomographs with known normal retinal anatomy. RESULTS: Optical coherence tomographs can discriminate the cross-sectional morphologic features of the fovea and optic disc, the layered structure of the retina, and normal anatomic variations in retinal and retinal nerve fiber layer thicknesses with 10-microns depth resolution. CONCLUSION: Optical coherence tomography is a potentially useful technique for high depth resolution, cross-sectional examination of the fundus.

Fovea Centralis↗
PubMed1995

Quantification of nerve fiber layer thickness in normal and glaucomatous eyes using optical coherence tomography.

PURPOSE: Quantitative assessment of nerve fiber layer (NFL) thickness in normal and glaucomatous eyes, and correlation with conventional measurements of the optic nerve structure and function. METHODS: We studied 59 eyes of 33 subjects by conventional ophthalmologic physical examination, Humphrey 24-2 visual fields, stereoscopic optic nerve head photography, and optical coherence tomography. RESULTS: Nerve fiber layer thickness as measured by optical coherence tomography demonstrated a high degree of correlation with functional status of the optic nerve, as measured by visual field examination (P = .0001). Neither cupping of the optic nerve nor neuroretinal rim area were as strongly associated with visual field loss as was NFL thickness (P = .17 and P = .21, respectively). Cupping correlated with NFL thickness only when the cup was small (cup-to-diameter ratio, 0.1 to 0.3) or large (cup-to-diameter ratio, 0.8 to 1.0) (P = .006); there was no correlation between cupping and NFL thickness otherwise. Nerve fiber layer, especially in the inferior quadrant, was significantly thinner in glaucomatous eyes than in normal eyes (P = .04). Finally, we found a decrease in NFL thickness with aging, even when controlling for factors associated with the diagnosis of glaucoma (P = .03). CONCLUSIONS: Nerve fiber layer thickness can be measured using optical coherence tomography. These measurements provide good structural and functional correlation with known parameters.

Female↗
PubMed1995

Imaging of macular diseases with optical coherence tomography.

BACKGROUND/PURPOSE: To assess the potential of a new diagnostic technique called optical coherence tomography for imaging macular disease. Optical coherence tomography is a novel noninvasive, noncontact imaging modality which produces high depth resolution (10 microns) cross-sectional tomographs of ocular tissue. It is analogous to ultrasound, except that optical rather than acoustic reflectivity is measured. METHODS: Optical coherence tomography images of the macula were obtained in 51 eyes of 44 patients with selected macular diseases. Imaging is performed in a manner compatible with slit-lamp indirect biomicroscopy so that high-resolution optical tomography may be accomplished simultaneously with normal ophthalmic examination. The time-of-flight delay of light backscattered from different layers in the retina is determined using low-coherence interferometry. Cross-sectional tomographs of the retina profiling optical reflectivity versus distance into the tissue are obtained in 2.5 seconds and with a longitudinal resolution of 10 microns. RESULTS: Correlation of fundus examination and fluorescein angiography with optical coherence tomography tomographs was demonstrated in 12 eyes with the following pathologies: full- and partial-thickness macular hole, epiretinal membrane, macular edema, intraretinal exudate, idiopathic central serous chorioretinopathy, and detachments of the pigment epithelium and neurosensory retina. CONCLUSION: Optical coherence tomography is potentially a powerful tool for detecting and monitoring a variety of macular diseases, including macular edema, macular holes, and detachments of the neurosensory retina and pigment epithelium.

Adult↗