PubMed Health⌕ Search

Biomedical subjects

J M Lin

Publications and source records attributed to J M Lin.

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

Ablation centration after active eye-tracker-assisted photorefractive keratectomy and laser in situ keratomileusis.

PURPOSE: To evaluate the ablation centration after active eye-tracker-assisted photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) and to investigate the effect of surgery, patient, and surgeon on the centration. SETTING: Department of Ophthalmology, China Medical College Hospital, Taichung, Taiwan, Republic of China. METHODS: This retrospective study comprised 177 eyes of 101 patients: 16 eyes had PRK and 161, LASIK. All laser treatments were performed with the aid of an eye tracker. The amount of decentration was analyzed by corneal topography. The factors influencing centration were divided into surgery related (PRK/LASIK), patient related (low/high myopia and effect of learning), and surgeon related (learning curve). RESULTS: The mean decentration was 0.33 mm in PRK eyes and 0.35 mm in LASIK eyes. For the surgery-related factor, there was no significant difference between the PRK and LASIK eyes. For the patient-related factors, centration was better in the second eye (effect of learning) and decentration was more severe in eyes with high myopia (low/high myopia). For the surgeon-related factor, there was no significant difference between eyes that had the first 50 LASIK procedures and those that had the last 50 procedures. CONCLUSIONS: An eye tracker, which makes the laser beam follow the eye's movements, helps to avoid severe decentration. This study showed, however, that an active eye-tracking system alone cannot ensure good centration. Patient cooperation and fixation are important.

Cornea↗
PubMed2000

Synthesis of anti-1,2-dihydroxy-3,4-epoxy-1,2,3, 4-tetrahydro-6-nitrochrysene and its reaction with 2'-deoxyguanosine- 5'-monophosphate, 2'-deoxyadenosine-5'-monophosphate, and calf thymus DNA in vitro.

The remarkable carcinogenic activity of 6-nitrochrysene (6-NC) in several animal models, and its environmental presence, suggest its potential importance with regard to human cancer development. Depending on the bioassay model, 6-NC can be activated by simple nitro reduction, ring oxidation, or by a combination of ring oxidation and nitro reduction. Only the first pathway has been clearly established. Thus, this study purports to unequivocally define the other pathways. Toward this end, we report for the first time the synthesis of anti-1,2-dihydroxy-3,4-epoxy-1,2,3, 4-tetrahydro-6-nitrochrysene (6-NCDE), a likely ultimate carcinogenic metabolite of 6-NC. Also, we describe our initial investigation of its binding with calf thymus DNA, 2'-deoxyguanosine-5'-monophosphate (2'-dGuo), and 2'-deoxyadenosine-5'-monophosphate (2'-dAdo) in vitro. These adduct markers were then employed for comparison with those obtained in the rat after in vivo treatment with 6-NC. On the basis of the results, it appears that the major adduct formed in the liver of rats treated with 6-NC is not derived from 6-NCDE.

Animals↗
PubMed2000

Effect of laser-assisted in situ keratomileusis on the retinal nerve fiber layer.

PURPOSE: To assess the effects of laser-assisted in situ keratomileusis (LASIK) on the retinal nerve fiber layer (RNFL). METHOD: In a prospective study, the RNFL thickness of 35 eyes of 20 consecutive patients was measured before and 1 month after LASIK by scanning laser polarimetry. RESULTS: The postoperative integrals and averages of RNFL thickness were statistically significantly lower than preoperative values, except in the temporal quadrant. CONCLUSION: LASIK has a significant effect on RNFL thickness determined by scanning laser polarimetry. Further studies are needed to determine whether the corneal compensation algorithms are affected by the keratome flap, whether the decreased averages and integrals of the RNFL thickness are reversible, and how to protect the RNFL.

Adult↗
PubMed2000

Antioxidant and hepatoprotective effects of Anoectochilus formosanus and Gynostemma pentaphyllum.

Anoectochilus formosanus Hay. and Gynostemma pentaphyllum Makino are popular folk medicines that have been used for treating hepatitis, hypertension and cancer in Taiwan. Our previous studies showed that these crude drugs exert antiinflammatory activity and hepatoprotective activity against CC14-induced liver damage. In this study, the antioxidant effect of these crude drugs and their hepatoprotective activity on acetaminophen-induced liver injury in rat was evaluated. Our results suggest that A. formosanus and G. pentaphyllum do have antioxidant effects. On acetaminophen-intoxicated model, the increased levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) by acetaminophen administration were reduced by treatment with these two herbs. In histological observation, gross necrosis in the centribular area, sinusoidal congestion, infiltration of the lymphocytes and Kupffer cells around the hepatic central vein, and loss of cell boundaries and ballooning degeneration were reduced with herbal treatment. However, the effect of A. formosanus and G. pentaphyllum is biphasic. Methanol extract (100 and 300 mg/kg) and water extract (300 and 500 mg/kg) of A formosanus and water extract (100, 300 and 500 mg/kg) of G. pentaphyllum enhanced the recovery of liver injury while treatment with 500 mg/kg of A. formosanus methanol extract resulted in serious hepatic injury.

Acetaminophen↗
PubMed2000

Anti-hypercholesterolaemia, antioxidant activity and free radical scavenger effects of traditional Chinese medicine prescriptions used for stroke.

The generation of oxygen radicals and lipid peroxidation may be factors in the cerebral damage secondary to ischaemia of the cerebrovascular disease, as in stroke. Five traditional Chinese medicinal prescriptions were investigated for their antioxidant activity: Shiee Fuu Jwu Iu Tang (TCMP1), Oh Yaw Shuen Chin Saan (TCMP2), Buu Yang Hwan Wuu Tang (TCMP3), Sheau Shiuh Ming Tang (TCMP4), and Chir Hwu Jia Long Guu Muu Lih Tang (TCMP5). Anti-lipid peroxidation, anti-superoxide formation and free radical scavenger activity were determined by the FeCl2--ascorbic acid-induced lipid peroxidation effects on lipids in-vitro, xanthine oxidase inhibition, cytochrome C system and an electron spin resonance spectrometer, respectively. The results showed that TCMP5 had greater anti-lipid peroxidation and anti-superoxide formation activity than the other prescriptions. TCMP4 had the greatest free radical scavenging effect, TCMP5 showed the greatest superoxide radical scavenger activity and TCMP3 showed the greatest hydroxyl radical scavenger activity. Tests were also performed to evaluate the effects of the five prescriptions on blood lipid in-vivo. The test showed that the prescriptions decreased the level of total cholesterol and LDL-cholesterol in serum in high cholesterol-fed rats. From these results, it seems probable that these prescriptions may be effective in the prevention and therapy of stroke and ischaemia.

Animals↗
PubMed2000

[Identification of turtle shell, tortoise plastron and their counterfeit products].

OBJECTIVE: To identify the commercial Chinese medicines turtle shell and tortoise plastron. METHOD: Morphological identification and differential thermal analysis (DTA). RESULT: 2 kinds of counterfeit turtle shell and 3 kinds of counterfeit tortoise plastron were found, and their morphological and DTA identification features were proposed. CONCLUSION: Sea turtle shells presently on the market are sham commodities of turtle shell, which derive from Lissemys punctata and Pelochelys bibroni indigenous to south Asia, while plastrons of Ocadia sinensis, Chelonia mydas and Lepidochelys olivacea are counterfeit products of tortoise plastron. Turtle shells, tortoise plastrons and their counterfeit products may be exactly distinguished by morphological and DTA features.

Animals↗
PubMed1999

Eukaryotic expression cloning with an antimetastatic monoclonal antibody identifies a tetraspanin (PETA-3/CD151) as an effector of human tumor cell migration and metastasis.

A monoclonal antibody (mAb), 50-6, generated by subtractive immunization, was found to specifically inhibit in vivo metastasis of a human epidermoid carcinoma cell line, HEp-3. The cDNA of the cognate antigen of mAb 50-6 was isolated by a modified eukaryotic expression cloning protocol from a HEp-3 library. Sequence analysis identified the antigen as PETA-3/CD151, a recently described member of the tetraspanin family of proteins. The cloned antigen was also recognized by a previously described antimetastatic antibody, mAb 1A5. Inhibition of HEp-3 metastasis by the mAbs could not be attributed to any effect of the antibodies on tumor cell growth in vitro or in vivo. Rather, the antibodies appeared to inhibit an early step in the formation of metastatic foci. In a chemotaxis assay, HEp-3 migration was blocked by both antibodies. HeLa cells transfected with and overexpressing PETA-3/CD151 were more migratory than control transfectants expressing little CD151. The increase in HeLa migration was inhibitable by both mAb 50-6 and mAb 1A5. PETA-3 appears not to be involved in cell attachment because adhesion did not correlate with levels of PETA-3 expression and was unaffected by mAb 50-6 or mAb 1A5. The ability of PETA-3 to mediate cell migration suggests a mechanism by which this protein may influence metastasis. These data identify PETA-3/CD151 as the first member of the tetraspanin family to be linked as a positive effector of metastasis.

Adenocarcinoma↗
PubMed1999

Cloning and expression of a wheat (Triticum aestivum L.) phosphatidylserine synthase cDNA. Overexpression in plants alters the composition of phospholipids.

We describe the cloning of a wheat cDNA (TaPSS1) that encodes a phosphatidylserine synthase (PSS) and provides the first strong evidence for the existence of this enzyme in a higher eukaryotic cell. The cDNA was isolated on its ability to confer increased resistance to aluminum toxicity when expressed in yeast. The sequence of the predicted protein encoded by TaPSS1 shows homology to PSS from both yeast and bacteria but is distinct from the animal PSS enzymes that catalyze base-exchange reactions. In wheat, Southern blot analysis identified the presence of a small family of genes that cross-hybridized to TaPSS1, and Northern blots showed that aluminum induced TaPSS1 expression in root apices. Expression of TaPSS1 complemented the yeast cho1 mutant that lacks PSS activity and altered the phospholipid composition of wild type yeast, with the most marked effect being increased abundance of phosphatidylserine (PS). Arabidopsis thaliana leaves overexpressing TaPSS1 showed a marked enhancement in PSS activity, which was associated with increased biosynthesis of PS at the expense of both phosphatidylinositol and phosphatidylglycerol. Unlike mammalian cells where PS accumulation is tightly regulated even when the capacity for PS biosynthesis is increased, plant cells accumulated large amounts of PS when TaPSS1 was overexpressed. High levels of TaPSS1 expression in Arabidopsis and tobacco (Nicotiana tabacum) led to the appearance of necrotic lesions on leaves, which may have resulted from the excessive accumulation of PS. The cloning of TaPSS1 now provides evidence that the yeast pathway for PS synthesis exists in some plant tissues and provides a tool for understanding the pathways of phospholipid biosynthesis and their regulation in plants.

Amino Acid Sequence↗
PubMed1999

V(D)J recombination catalyzed by mutant RAG proteins lacking consensus DNA-PK phosphorylation sites.

The process of antigen receptor gene rearrangement, V(D)J recombination, involves DNA cleavage by the RAG-1 and RAG-2 proteins. Cleavage generates covalently sealed (hairpin) DNA ends, termed coding ends, which must be opened by an endonuclease prior to joining. Resolution of these hairpin ends requires the activity of the DNA-dependent protein kinase (DNA-PK), a protein kinase whose specific role is yet undetermined. It has been suggested that phosphorylation of one or both RAG proteins by DNA-PK is required to activate or recruit the hairpin-opening nuclease. Furthermore, very recent work has shown that RAG proteins themselves can open hairpins. These data raise the possibility that DNA-PK-mediated phosphorylation of the RAG proteins could regulate the hairpin opening reaction. To test this hypothesis, we constructed mutant versions of RAG-1 and RAG-2 in which all four DNA-PK consensus phosphorylation sites were removed by site-directed mutagenesis. Our data provide conclusive evidence that phosphorylation of these conserved serine/threonine residues is not required for hairpin opening or joining of V(D)J recombination intermediates.

Amino Acid Sequence↗
PubMed1999

Synthesis of anti-7,8-dihydroxy-9,10-epoxy-7,8,9, 10-tetrahydro-11-methylbenzo[a]pyrene and its reaction with DNA.

Substitution of a methyl group in the bay region can enhance the tumorigenicity of polycyclic aromatic hydrocarbons such as chrysene, benz[a]anthracene, and others. This phenomenon has been related to facile DNA adduct formation of bay region diol epoxides with a methyl group and epoxide ring in the same bay. While anti-7, 8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene and its DNA adduct formation have been studied extensively, it is not known whether a methyl substituent in the bay region alters the reactivity of DNA in this system. This is of interest because 11-methylbenzo[a]pyrene, which has a bay region methyl group, is more tumorigenic than benzo[a]pyrene. To examine the question, we have devised and employed an efficient synthesis based on photochemical cyclization, and prepared anti-7,8-dihydroxy-9, 10-epoxy-7,8,9,10-tetrahydro-11-methylbenzo[a]pyrene, the likely ultimate carcinogen of 11-methylbenzo[a]pyrene. We have then reacted anti-7,8-dihydroxy-9,10-epoxy-7,8,9, 10-tetrahydro-11-methylbenzo[a]pyrene with calf thymus DNA and found that it gives three major adducts. These were identified as having resulted from cis- and trans-ring opening of the (S,R,R, S)-enantiomer and from trans-ring opening of the (R,S,S, R)-enantiomer. The standard deoxyguanosine adduct markers were prepared, and their structures were tentatively assigned on the basis of their CD and 1H NMR spectra. The adduct distribution of anti-7,8-dihydroxy-9,10-epoxy-7,8,9, 10-tetrahydro-11-methylbenzo[a]pyrene is quite different from that observed in the reaction of DNA with the corresponding diol epoxides of benzo[a]pyrene or with 5-methylchrysene. The heterogeneity of adducts obtained with anti-7,8-dihydroxy-9,10-epoxy-7,8,9, 10-tetrahydro-11-methylbenzo[a]pyrene thus may be related to the enhanced tumorigenicity of 11-methylbenzo[a]pyrene.

Benzopyrans↗
PubMed1999

Nitroreduction of 4-nitropyrene is primarily responsible for DNA adduct formation in the mammary gland of female CD rats.

We determined whether DNA adducts derived from 4-nitropyrene (4-NP) are formed via nitroreduction or ring oxidation. DNA adduct markers derived from both pathways were prepared and, consequently, were compared with those obtained in vivo in rats treated with 4-NP. Following in vitro reaction of 9,10-epoxy-9,10-dihydro-4-nitropyrene (4-NP-9,10-epoxide), an intermediate metabolite derived from ring oxidation of 4-NP, with calf thymus DNA (average level of binding in two determinations was 8.5 nmol/mg of DNA), DNA was enzymatically hydrolyzed to deoxyribonucleosides and the DNA hydrolysates were analyzed by HPLC. Electrospray mass and 1H NMR spectra of the major products indicated that these adducts are deoxyguanosine (dG) derivatives that resulted from N2-dG substitution at the 9- or 10-position of the pyrene nucleus. However, these adducts were not detected in vivo in the rat mammary gland and liver following the administration of 4-NP. Nitroreduction of 4-NP catalyzed by xanthine oxidase in the presence of DNA resulted in three major putative DNA adducts (level of binding of 12.0 +/- 1.1 nmol/mg of DNA, n = 4) designated as peak 1 (46%), peak 2 (25%), and peak 3 (17%). Although peak 1 was further resolved into peaks 1a and 1b, both were unstable and gradually decomposed to peak 2, and the latter was unequivocally identified as pyrene-4,5-dione. On the basis of electrospray mass spectral analysis, peak 3 was tentatively identified as a deoxyinosine-derived 4-aminopyrene adduct. None of the adducts derived from nitroreduction of 4-NP catalyzed by xanthine oxidase coeluted with the synthetic standard N-(deoxyguanosin-8-yl)-4-aminopyrene prepared by reacting dG with N-acetoxy-4-aminopyrene. Nevertheless, HPLC analysis of the hydrolysates of liver and mammary DNA obtained from rats treated with [3H]-4-NP yielded four radioactive peaks, all of which coeluted with the markers derived from the nitroreduction pathway. These results indicate that nitroreduction is primarily responsible for DNA adduct formation in the liver and, especially, in the mammary gland which is the organ susceptible to carcinogenesis by this environmental agent.

Animals↗
PubMed1999

Correlation of the flow patterns among the four pulmonary veins as assessed by transesophageal echocardiography: influence of significant mitral regurgitation.

AIMS: To evaluate the correlation of the flow patterns of the four pulmonary veins as assessed by transesophageal echocardiography and the influence of significant mitral regurgitation on this correlation. METHODS AND RESULTS: Eighty-eight patients with normal sinus rhythm and variable underlying cardiovascular diseases underwent transthoracic and transesophageal echocardiographic studies. Doppler flow of the four pulmonary veins could not be adequately interpreted in 19 patients (22%). The left atrial dimension of these patients was significantly larger than that of the patients with complete study of the flow in the four pulmonary veins (49 +/- 6 vs. 43 +/- 7 mm; p < 0.05). Of the 69 patients with complete evaluation of the four pulmonary veins, 48 patients without significant mitral regurgitation were analyzed as group A, and the remaining 21 patients as group B. The peak systolic and diastolic forward flow velocities of the four pulmonary veins were measured and the ratio of peak systolic (S) to diastolic (D) flow velocity was calculated. Group A had a significantly larger S/D ratio in all four pulmonary veins than group B (p < 0.05 in each pulmonary vein measurement). There was good correlation of the flow pattern represented as S/D ratio between left upper and lower pulmonary veins (r = 0.90) and between right upper and lower pulmonary veins (r = 0.89) in group A. The correlation of the flow pattern among the four pulmonary veins deteriorated in group B. CONCLUSION: Pulmonary veins on the same side share rather similar flow patterns in comparison with pulmonary veins on the opposite sides. The correlation of flow patterns among the four pulmonary veins is good in subjects without significant mitral regurgitation, but it worsens in patients with significant mitral regurgitation. Therefore, cautious interpretation of flow patterns of the four pulmonary veins in patients with significant regurgitation is indicated for grading the severity of mitral regurgitation.

Aortic Valve↗
PubMed1999

Preserved pulsatile insulin release from prediabetic mouse islets.

During the development of type I diabetes, the plasma insulin pattern changes. Because the islet secretory pattern has been implicated in this phenomenon, insulin release was measured from female nonobese diabetic (NOD) mouse islets isolated at different ages. Islets from 5-week-old mice were used as controls because they had no infiltrating mononuclear cells and insulin release rose almost 9-fold with maintained oscillatory frequency when the glucose concentration was raised from 3 to 11 mM. Islets isolated from 13- and 25-week-old mice were infiltrated with mononuclear cells. In these islets, increase in the glucose concentration from 3 to 11 mM only doubled insulin release. However, despite the cellular infiltration, insulin release was pulsatile. Islets from 13-week-old mice had reduced glucose oxidation rate. Culture of such islets for 7 days at 11.1 mM glucose causes a decrease in the number of mononuclear cells infiltrating the islets, which in the present study was accompanied by a normalization of both glucose oxidation and glucose-induced insulin release. In the presence of the mitochondrial substrate alpha-keto-isocaproate (5 mM) both control and infiltrated islets responded with pronounced insulin pulses with similar amplitudes. The results suggest that the deranged plasma insulin pattern observed during the development of type I diabetes may be related to decrease in the insulin pulse amplitude rather than loss of the pulsatile release from the islets.

Aging↗
PubMed1998

Aliphatic aldehydes and allethrin in mosquito-coil smoke.

Presence of aliphatic aldehydes and allethrin in the smoke produced by two brands of mosquito-coil was determined by high performance liquid chromatography. It was observed that burning mosquito-coil produces a greater amount of formaldehyde, acetaldehyde and acrolein in the gaseous phase, whereas lesser amount of particulate-bounded aldehydes. Aldehydes bounded in particulates were, however, enriched in terms of concentration. Allethrin was found to occur only in particulates of 0.1-1.0 micron size. The results reveal that allethrin may not be capable of attacking the mosquitoes effectively.

Air Pollutants↗
PubMed1998

Evaluation of the hepatoprotective and antioxidant activity of Boehmeria nivea var. nivea and B. nivea var. tenacissima.

In this study, the relationship between liver protective effects and antioxidant activity of Boehmeria nivea var. nivea (= B. nivea) and B. nivea var. tenacissima (= B. frutescens) was investigated. The water extracts of both plants exhibited a hepatoprotective activity against CCl4-induced liver injury. B. nivea var. nivea and B. nivea var. tenacissima, also showed anti-oxidant effects in FeCl2-ascorbate induced lipid peroxidation in rat liver homogenate. Moreover, the active oxygen species scavenging potencies were evaluated by an electron spin resonance (ESR) spin-trapping technique. B. nivea var. tenacissima displayed better superoxide radical scavenging activity than B. nivea. Based on these findings, we suggest that in the liver protective and antioxidative effects of B. nivea var. nivea and B. nivea var. tenacissima, possibly involve mechanisms related to free radical scavenging effects.

Animals↗
PubMed1998

Nonoperative management for extensive hepatic and splenic injuries with significant hemoperitoneum in adults.

BACKGROUND: Although several retrospective studies have been published concerning nonoperative management of minor liver and spleen injuries, few studies have prospectively analyzed the results of nonoperative management for higher-grade liver and spleen injuries. Is it possible to manage extensive hepatic or splenic injuries with hemoperitoneum nonoperatively? The current study was conducted to evaluate the safety of nonoperative management of blunt hepatic and splenic trauma with significant hemoperitoneum in hemodynamically stable patients regardless of injury severity. METHODS: We used the nonoperative methods prospectively to treat consecutive patients with blunt spleen or liver injury during a 35-month period. Patients with unstable conditions underwent emergency laparotomies, and those who were stable underwent abdominal computed tomography for further evaluation. We analyzed the clinical characteristics and the success rate of this method thoroughly. RESULTS: Twenty-four patients with severe hepatic or splenic injuries treated nonoperatively were included in this study. Among these 24 patients, 18 (75%) with hepatic or splenic injuries had grades of III or greater on the Organ Injury Scale. Twenty patients (83.3%) had moderate to large amounts of hemoperitoneum. Four patients (16.7%) failed at observation and underwent emergency celiotomy, two for liver-related and two for spleen-related causes. There were no differences between the nonoperative and operative management groups in terms of mean age, initial systolic blood pressure, initial heart rate, emergency room fluid requirement except emergency blood transfusion, abdominal complications, and hospital length of stay. CONCLUSION: We suggest that nonoperative management may be undertaken successfully in appropriately designed areas with close observation for the hemodynamic stable patient.

Adolescent↗
PubMed1998

Raffinee, a free radical scavenger, in the treatment of subacute stage brain and spinal cord lesions: a case report.

This report presents the effects of the natural antioxidant formulation "Raffinee" in treatment of a case with subacute cerebellar hemorrhage and a case with subacute incomplete cervical cord injury. Four days after onset of cerebellar hemorrhage, the regimen started and ameliorated severe headache and dizziness within 3 days. Forty-five days after incomplete spinal cord injury with marked edema of cervical cord, the regimen started. Excellent motor and sensory function recovery were obtained within one month with remission of cord edema. The dosage of "Raffinee" is equivalent to 2,280,000 units of superoxide radical scavenging activity and 47,000 units of hydroxyl radical scavenging activity. Based on the secondary injury theory, superoxide and hydroxyl radical scavengers may have a valuable use in subacute central nervous system (CNS) lesions. Further larger scale of randomized, placebo-controlled, double-blind clinical trials are indicated to verify the effect of "Raffinee" on subacute CNS lesions.

Adult↗