Biomedical subjects

S C Lin

Publications and source records attributed to S C Lin.

At least 55 records · Page 3Linked to original sources

PubMed2000

Primary structure and function analysis of the Abrus precatorius agglutinin A chain by site-directed mutagenesis. Pro(199) Of amphiphilic alpha-helix H impairs protein synthesis inhibitory activity.

Abrus agglutinin (AAG), a low-toxicity protein from the plant Abrus precatorius, is less lethal than abrina (ABRa) in mice (LD(50) = 5 mg/kg versus 20 microg/kg of body weight). Nucleotide sequence analysis of a cDNA clone encoding full-length AAG showed an open reading frame with 1641 base pairs, corresponding to a 547-amino acid residue preproprotein containing a signal peptide and a linker region (two amino acid residues) between the AAG-A and AAG-B subunits. AAG had high homology to ABRa (77.8%). The 13 amino acid residues involved in catalytic function, which are highly conserved among abrins and ricins, were also conserved within AAG-A. The protein synthesis inhibitory activity of AAG-A (IC(50) = 3.5 nM) was weaker than that of ABRa-A (0.05 nM). Molecular modeling followed by site-directed mutagenesis showed that Pro(199) of AAG-A, located in amphiphilic helix H and corresponding to Asn(200) of ABRa-A, can induce bending of helix H. This bending would presumably affect the binding of AAG-A to its target sequence, GpApGpAp, in the tetraloop structure of the 28 S rRNA subunit and could be one of the major factors contributing to the relatively weak protein synthesis inhibitory activity and toxicity of AAG.

Abrin↗

PubMed2000

Foot progression angle and ankle joint complex in preschool children.

OBJECTIVE: The influence of foot progression angle on the ankle joint and the effects on gait patterns and mechanisms in skeletally normal preschool children was investigated. DESIGN: Kinematics and kinetics of the ankle joint were analyzed for preschool children who were skeletally normal but walked with different foot progression angle. BACKGROUND: The most frequent reasons for preschool children to be brought to a paediatric orthopaedic clinic are toe-in and toe-out. Without understanding the biological and biomechanical implications, treatment for these problems can be very confusing. METHODS: Gait analysis was performed in 86 skeletally normal preschool children. Children were grouped according to their foot progression angles. Analysis of the kinematics and kinetics of the ankle joint was intended to elucidate the gait mechanism. RESULTS: Children with different foot progression angles had distinctive patterns of spatio-temporal parameters, ground reaction force, joint angle, moment, power, and mechanical work of the ankle joints. The differences were organized and explained as different walking patterns and tactics. CONCLUSIONS: Skeletally normal preschool children with excessive toe-in or toe-out foot progression angles are not necessarily in some diseased status. They were instead related to different walking patterns. Aggressive treatment for these problems is not recommended.RelevanceThese results suggest that toe-in and toe-out are related to walking speed which has distinct influences on the kinematics and kinetics of the ankle joint. Though the observed problems were seemingly only in the transverse plane, they are in fact three-dimensional and have a mutually close relationship. The findings could be linked to the promptness of muscle response and the habits of walking in preschool children. Better understanding of possible mechanisms will help parents and paediatricians decide on the most appropriate treatment for these children.

Ankle Joint↗

PubMed2000

The role of the antennal glands in ion and body volume regulation of cannulated Penaeus monodon reared in various salinity conditions.

Urinary production rate and the osmotic and ionic concentrations in both urine and hemolymph were measured in cannulated intermolt Penaeus monodon which were either abruptly transferred from 45 ppt seawater to 15 ppt seawater (Experiment 1) or acclimated to 5, 25 and 45 ppt seawater (Experiment 2). In Experiment 1, urinary magnesium concentration fell dramatically from 228 to 30 mEq/l within 4 h post-transfer, but 8 h after transfer, U/H (urine/hemolymph) ratios stabilized at between 1.0 and 2.5. Sodium was higher in urine than in hemolymph during the first 24 h after transfer, while potassium was lower in urine than in hemolymph until 72 h after transfer, which suggests that sodium and potassium concentrations are regulated by the antennal gland after an abrupt change in media. In Experiment 2, the urinary production rate of P. monodon decreased as salinity increased, suggesting that the antennal glands also regulate body volume. In the acclimated shrimps of Experiment 2, the antennal glands did not appear to regulate osmolarity or the concentration of chloride, sodium, potassium, and calcium ions, but as salinity increased, U/H ratios of magnesium increased from 2.3 to 13.5, and active secretion by the antennal gland accounted for 57 approximately 93% of the total magnesium excretion through urine. These results suggest that active secretion of magnesium by the antennal gland enable this shrimp to maintain hypoionic levels of magnesium in the hemolymph.

Animals↗

PubMed2000

Association of aberrant p53 and p21(WAF1) immunoreactivity with the outcome of oral verrucous leukoplakia in Taiwan.

The expression of p53 and p21WAF1 in 53 oral verrucous leukoplakias (OVLs), mostly non-dysplastic lesions, was investigated to ascertain the role of such events in malignant conversion. Immunohistochemical analysis revealed aberrant p53 and p21WAF1 immunoreactivity in 51% (27 cases) and 75% (40 cases), respectively. After an average follow-up period of three and a half years, histopathological examination revealed that 22 (42%) cases had developed oral squamous cell carcinoma (OSCC), 14 (26%) cases had undergone recurrence, and 17 (32%) cases were free of disease. The oncogenic potential of this subset of premalignant lesions warrants attention. A significant difference in the frequency of OSCC progression/recurrence was noted in lesions bearing aberrant immunoreactivity of either p53 (93% vs 42%; P=0.00008) or p21WAF1 (80% vs 32%; P=0.002) in comparison with lesions without immunoreactivity. This study suggested that the aberrant immunoreactivity of p53 and p21WAF1 may represent important alterations of OVL and could affect the outcome of this lesion.

Adult↗

PubMed2000

Alterations of p16/MTS1 gene in oral squamous cell carcinomas from Taiwanese.

To determine the alterations of the p16/MTS1 gene in oral squamous cell carcinoma (OSCC), we examined in Taiwanese patients the mutation, deletion and methylation of p16/MTS1 in primary OSCCs associated mostly with betel quid (BQ)/tobacco use. Among 110 tumors undergoing mutational analyses, seven (6%) showed mutations in exon 2 or the intron 1/exon 2 splice site. All but one mutation disrupted the encoded proteins. Base transitions represented the vast majority (6/7) of the mutations identified in BQ/tobacco consuming subjects. It was noted that 15/56 (27%) tumors examined by restriction fragment methylation analysis revealed a significant level of methylation in different loci of exon 1 as compared with the respective non-cancerous tissue. Mutation of p16/MTS1 was exclusively identified in carcinomas of buccal mucosa, whereas methylation of the p16/MTS1 promoter region occurred preferentially in carcinomas of the tongue (54%) rather than at other sites (22%). Homozygous deletion was not found in 56 paired samples examined, nor was hemizygous deletion indicated in 12 informative cases. The results indicated aberrant methylation and mutation as the molecular abnormality of p16/MTS1 in the OSCC from Taiwanese.

Adult↗

PubMed2000

Increased transforming growth factor-beta (TGF-beta)-secreting T cells and IgA anti-cardiolipin antibody levels during acute stage of childhood Henoch-Schönlein purpura.

Henoch-Schönlein purpura (HSP) is a small vessel vasculitis characterized by increased serum IgA and IgA-dominant immune complex deposition in lesions. The involvement of IgA implies a probable role for TGF-beta, a major factor in IgA production, in the pathogenesis of HSP. Among IgA antibodies, serum IgA anti-cardiolipin antibodies (aCL) have been found in many diseases, including vasculitis. In addition to the clinical presentations and laboratory parameters, we further investigated the roles of IgA aCL and TGF-beta in childhood HSP. Twenty-six Chinese children with the diagnosis of HSP were enrolled. Blood samples from these patients were collected at both acute and convalescent stages. Intracellular staining of lymphocytes was performed to enumerate type 1 (interferon-gamma-secreting), type 2 (IL-4-secreting), and type 3 (TGF-beta-secreting) helper T cells. Serum levels of TGF-beta were detected by ELISA. Serum IgA aCL of 21 of 26 patients at the acute stage, 11 of them at the convalescent stage, were measured by ELISA. The data showed that IgA aCL serum levels were significantly elevated in patients compared with healthy controls (P < 0.001), and those patients at the convalescent stage (P < 0.001). In addition, TGF-beta-secreting T cells were significantly elevated during the acute stage, and decreased at the convalescent stage. Although more studies are needed, the high prevalence of IgA aCL and increased TGF-beta-secreting T cells in children with acute HSP revealed some points which should permit a better understanding of the pathogenesis of HSP.

Acute Disease↗

PubMed2000

The use of the motion analysis system for evaluation of loss of movement in the finger.

We have used the motion analysis system to measure loss of finger movement after injury. The motion analysis system can provide information about the dynamic angular changes of each finger joint and the fingertip motion area for the injured finger. The latter can be used to calculate the percentage of fingertip motion area preserved. A stiff finger may show limited fingertip motion area with the finger joints tending to flex and extend together.

Adult↗

PubMed2000

Crystallization of agglutinin from the seeds of Abrus precatorius.

Agglutinin protein purified from the seeds of Abrus precatorius has a high antitumour activity and was crystallized at room temperature with polyethylene glycol 8000 as the precipitant. The agglutinin crystal diffracted to 3.45 A and belongs to one of two possible tetragonal space groups, P4(1)2(1)2 or P4(3)2(1)2, with unit-cell parameters a = b = 141.91, c = 105.63 A. The asymmetric unit contains a heterotetrameric protein molecule of molecular weight 134 kDa and has a solvent content of approximately 38%.

Crystallization↗

PubMed2000

The hepatoprotective effects of Solanum alatum Moench. on acetaminophen-induced hepatotoxicity in mice.

Solanum alatum Moench. has been shown to have a protective effect against carbon tetrachloride (CCl4)-induced liver injury. Solanum alatum treatment (100 mg/kg, p.o.) decreased the elevation of serum alanine aminotransferase (ALT; GPT) and aspartate aminotransferase (AST; GOT) induced by acetaminophen (paracetamol) (600 mg/kg, i.p.) administration. It also decreased the extent of visible necrosis in liver tissue. In addition, Solanum alatum treatment restored hepatic glutathione (GSH) depletion induced by acetaminophen (600 mg/kg, i.p.) administration. Microsomal enzyme levels such as P-450, reductase, and aniline hydroxylation enzyme were also restored to normal levels after Solanum alatum administration. The hepatoprotective mechanism may function through direct binding with acetaminophen toxic metabolites, decreasing the attraction of acetaminophen metabolites for other cellular GSH or thiol protein. Additionally, Solanum alatum treatment increased the concentration of hepatic GSH and maintained a high level activity of GSTase, which led to acceleration of the excretion of toxic acetaminophen metabolites.

Acetaminophen↗

PubMed2000

Hepatoprotective effects of Arctium lappa on carbon tetrachloride- and acetaminophen-induced liver damage.

The root of Arctium lappa Linne (A. lappa) (Compositae), a perennial herb, has been cultivated for a long time as a popular vegetable. In order to investigate the hepatoprotective effects of A. lappa, male ICR mice were injected with carbon tetrachloride (CCl4, 32 microl/kg, i.p.) or acetaminophen (600 mg/kg, i.p.). A. lappa suppressed the SGOT and SGPT elevations induced by CCl4 or acetaminophen in a dose-dependent manner and alleviated the severity of liver damage based on histopathological observations. In an attempt to elucidate the possible mechanism(s) of this hepatoprotective effect, glutathione (GSH), cytochrome P-450 (P-450) and malondialdehyde (MDA) contents were studied. A. lappa reversed the decrease in GSH and P-450 induced by CCl4 and acetaminophen. It was also found that A. lappa decreased the malondialdehyde (MDA) content in CCl4 or acetaminophen-intoxicated mice. From these results, it was suggested that A. lappa could protect the liver cells from CCl4 or acetaminophen-induced liver damages, perhaps by its antioxidative effect on hepatocytes, hence eliminating the deleterious effects of toxic metabolites from CCl4 or acetaminophen.

Acetaminophen↗

PubMed2000

Childhood mixed connective tissue disease.

Two girls with mixed connective tissue disease (MCTD) were treated in our hospital in the past 5 years. Patient 1, a 10-year-old girl presenting with migratory arthralgia, had an initial diagnosis of juvenile rheumatoid arthritis. Muscle weakness with elevated levels of creatine kinase and liver enzymes, sclerodactyly, Raynaud's phenomenon and heliotrope sign developed subsequently in the following 3 years. Patient 2, a 13-year-old girl, had been treated for suspected systemic lupus erythematosus since 9 years of age. She presented with lymphadenopathy, arthralgia, pericardial effusion, and paralytic ileus. The symptoms waxed and waned. Sclerodactyly, Raynaud's phenomenon, proteinuria, and hypertension were also noted. Both patients had high serum titers of antinuclear antibody (speckled pattern, 1:5120) and were seropositive for antiribonuclear protein antibody. Intravenous immunoglobulin, prednisolone, cyclosporine A, and nonsteroidal anti-inflammatory drugs (NSAIDs) were given to patient 1. Patient 2 received cyclosporine A, prednisolone, and methylprednisolone pulse therapy. The disease has been well controlled for 2 years by low-dose immunosuppressants and NSAIDs. MCTD is a rare juvenile rheumatic disease: early identification and appropriate treatment can improve the disease outcome.

Adolescent↗

PubMed2000

Lichen sclerosus et atrophicus, bullous morphea, and systemic lupus erythematosus: a case report.

Lichen sclerosus et atrophicus (LSA) rarely coexists with morphea, especially when bullae occur in lesions of morphea. Here we report the case of a 15-year-old girl with this condition, who also fulfilled four out of 11 diagnostic criteria for systemic lupus erythematosus (SLE). Tissue biopsy of different skin lesions showed LSA in the regions of bullous morphea, that has rarely been reported in the literature.

Adolescent↗

PubMed2000

Comparison of two-dimensional and three-dimensional techniques for determination of facial motion--absolute movement in a local face frame.

BACKGROUND AND PURPOSE: Few studies have used motion analysis in the study of facial animation. A facial animation model using an expert vision motion analysis system was developed in this study to quantitatively evaluate absolute movement during five facial animations. METHODS: Skin markers were adhered to the face of each subject at 16 anatomic landmarks selected to represent the functional movement of the facial muscles. Three of the 16 skin markers were used to establish a local face frame with the origin in the mid-point of the face. All of the coordinates measured in the laboratory frame were rotated and translated to the local face frame for analysis. The trajectory of the facial markers was evaluated from the local face frame when comparing two-dimensional (2-D) displacement of skin markers (frontal plane) with three-dimensional (3-D) values by paired Student's t-test. RESULTS: Although the correlation of 2-D and 3-D displacements of skin markers was high (r > 0.69), the differences between 2-D and 3-D motion were significant (p < 0.001). The 2-D displacement of skin markers underestimated the 3-D facial animation in each marker and animation. There were no significant differences in the movement of both mouth angles or of the eyes. Thirty repeated measurements of a subject revealed good concentration in 3-D displacement, velocity, and angle of movement in smiling. The measurement error was less than 0.06 mm. The normative displacement of individual anatomic landmarks was evaluated to avoid size differences of individual faces. CONCLUSIONS: We suggest that the expert vision motion analysis technique is feasible for quantitative evaluation of absolute facial movement and would be useful for further clinical evaluation of patients with facial palsy.

Adult↗

PubMed2000

P53 expression, p53 and Ha-ras mutation and telomerase activation during nitrosamine-mediated hamster pouch carcinogenesis.

Squamous cell carcinomas (SCC) induced in hamster buccal pouch (HBP) by 22 weeks of topical N-methyl-N-benzylnitrosamine (MBN) treatment (twice-weekly, 10 mg MBN/ml propylene glycol) were evaluated for: (i) altered expression of p53 using immunohistochemistry (IHC); (ii) mutations in Ha-ras and p53 using PCR/single strand conformation polymorphism (SSCP); (iii) telomerase activity using the telomerase repeat amplification protocol (TRAP). Precancerous lesions were also evaluated using p53 IHC. Hamsters were killed for lesion analysis at either 3 days (group A, eight hamsters, 89 carcinomas) or 7 weeks (group B, six hamsters, 105 carcinomas) following the final MBN application. Between 3 days and 7 weeks post-treatment the proportion of tumors exhibiting p53 IHC activity (at least 10% of nuclei stained using D07 antibodies for detection of both mutant and wild-type p53) fell from 91 to 50%. However, during this same post-treatment period the frequency of tumors analyzed exhibiting confirmed sequence alterations in the conserved exons (E5-E8) of p53 remained constant (5/15 = 33% in group A versus 14/45 = 31% in group B). Heightened expression of wild-type p53 resulting from DNA damage in the immediate post-treatment period is likely to have contributed to the high proportion of group A tumors exhibiting p53 IHC activity. Nearly 80% of the identified p53 mutations were G-->A and C-->T transitions. The identified p53 point mutations occurred at or near (within three codons) of the corresponding hot-spot codons (175, 245, 248 and 273) of human oral SCC. The proportion of group A and group B tumors analyzed exhibiting Ha-ras mutations was 1/15 (7%) and 7/45 (16%), respectively. Only four of the observed eight Ha-ras mutations occurred in codons known to result in activation of this gene. Telomerase activation was demonstrated in 11 of 13 group A tumors (85%) and in 23 of 24 (96%) group B tumors analyzed. The alterations in p53, Ha-ras and telomerase activity observed in this HBP-MBN model are similar in many respects to those observed in the analogous human lesions of the head and neck. This model may be particularly useful for development of cancer chemoprevention regimens and multimodality cancer therapies.

Animals↗

PubMed2000

Establishment and characterization of a cell line (HCDB-1) derived from a hamster buccal pouch carcinoma induced by DMBA and Taiwanese betel quid extract.

This study identified that the carcinogenesis of hamster buccal pouch (HBP) induced by 7,12-dimethylbenz[a]anthracene (DMBA) was greatly enhanced (18 folds) by a combination treatment with Taiwanese betel quid (BQ) extract. A new cell line, HCDB-1, has been established from induced carcinomas. The cultured monolayer cells were epithelioid in shape with irregular nuclei. They demonstrated abundant cytokeratin and tonofilaments; however, ultrastructural well-organized desmosomes were lacking. The HCDB-1 cell exhibited population doubling in 19 h and was highly tumorigenic in nude mice. A C-->T transition at codon 141 (Ala to Val) of the p53 gene was detected in this cell. This mutation is equivalent to a specific temperature-sensitive mouse p53Ala135Val mutant that causes transformation by shifting to 37.5 degrees C. HCDB-1 is the first cell line established from the HBP model of oral carcinogenesis induced by DMBA/Taiwanese BQ extract. It might be valuable for exploring the molecular pathogenesis of oral cancer.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed2000

Alterations of adenomatous polyposis Coli (APC) gene in oral squamous cell carcinoma.

The present study assessed the roles of Adenomatous Polyposis Coli (APC) tumor suppressor gene during oral carcinogenesis. Reduction of APC transcript levels and APC loss of heterozygosity (LOH) were found in 39% (7/18) and 29% (10/34) cases of oral squamous cell carcinoma (OSCC), respectively. The apparent APC heterozygosity (27%) in non-cancerous matched oral tissue (NCMOT) adjacent to OSCC at an exon 11 locus was significantly lower than normally found in the Taiwanese population (49%). These findings suggest that the allelic status of APC could indicate a cancer risk. No polymorphism of 11307 allele of APC was identified in NCMOT or OSCC. Our data indicated that alterations of APC are frequent molecular changes of OSCC. Advances in understanding of the APC alterations that accompany OSCC development might provide a means for early diagnosis and possibly new therapeutic strategies.

Carcinoma, Squamous Cell↗

PubMed2000

Tissue-specific cancer-related serpin gene cluster at human chromosome band 3q26.

Approximately one quarter of the identified human serpin genes are cancer-related and clustered mainly at two distinct loci: 6p25 and 18q21. We have studied a novel serpin gene cluster at 3q26 containing at least two recently identified members: the pancreas-specific protease inhibitor, pancpin (PI14), and the brain-associated protease inhibitor, neuroserpin (PI12). In this, unlike a previous study, both PI14 and PI12 at 3q26 were found to consist of 9 exons and 8 introns and to share a perfectly conserved gene organization whose pattern is very different from that of the ov-serpin family. This distinct pattern appears identical in the genomic structures of human plasminogen activator inhibitor-1 (PAI1) at 7q21 and protease nexin 1 (PI7) at 2q33-35, confirming that these four genes in three different chromosomes form a discrete subset within the serpin superfamily. As in the other three members whose gene expression is altered during tumorigenesis, PI12 expression was found to be down-regulated in tumor brain tissues and in two brain cancer cell lines: U-87 MG and H4. By screening genomic libraries, we isolated two overlapping clones showing that the marker SGC32223 (centromere) is located within intron F of PI12 and the marker WI-10077 (telomere) is located downstream of the 3'-flanking region of PI14. This finding indicates that the distance between human PI14 and PI12 is approximately 100 kb, and hence we speculate that other tissue-specific cancer-related serpin genes are likely to reside within this 3q26.1 cluster region.

Amino Acid Sequence↗

PubMed1999

Studies on effective PCR screening strategies for white spot syndrome virus (WSSV) detection in Penaeus monodon brooders.

We re-tested stored (frozen) DNA samples in 5 independent polymerase chain reaction (PCR) replicates and confirmed that equivocal test results from a previous study on white spot syndrome virus (WSSV) in brooders and their offspring arose because amounts of WSSV DNA in the test samples were near the sensitivity limits of the detection method. Since spawning stress may trigger WSSV replication, we also captured a fresh batch of 45 brooders for WSSV PCR testing before and after spawning. Replicates of their spawned egg batches were also WSSV PCR tested. For these 45 brooders, WSSV prevalence before spawning was 67% (15/45 1-step PCR positive, 15/45 2-step PCR positive and 15/45 2-step PCR negative). Only 27 (60%) spawned successfully. Of the successful spawners, 56% were WSSV PCR positive before spawning and 74% after. Brooders (15) that were heavily infected (i.e. 1-step PCR positive) when captured mostly died within 1 to 4 d, but 3 (20%) did manage to spawn. All their egg batch sub-samples were 1-step PCR positive and many failed to hatch. The remaining 30 shrimp were divided into a lightly infected group (21) and a 2-step PCR negative group (9) based on replicate PCR tests. The spawning rates for these 2 groups were high (81 and 78%, respectively). None of the negative spawners (7) became WSSV positive after spawning and none gave egg samples positive for WSSV. In the lightly infected group (21), 6 brooders were 2-step WSSV PCR negative and 15 were 2-step WSSV PCR positive upon capture. However, all of them were WSSV PCR positive in replicate tests and after spawning or death. Four died without spawning. The remaining 17 spawned but only 2 gave egg samples PCR negative for WSSV. The other 15 gave PCR positive egg samples, but they could be divided into 2 spawner groups: those (7) that became heavily infected (i.e. 1-step PCR positive) after spawning and those (8) that remained lightly infected (i.e. became or remained 2-step PCR positive only). Of the brooders that became heavily infected after spawning, almost all egg sample replicates (91 %) tested 2-step PCR positive. One brooder even gave heavily infected (i.e. 1-step PCR positive) egg samples. For the brooders that remained lightly infected after spawning, only 27% of the egg sample replicates were 2-step PCR positive. Based on these results, we recommend that to avoid false negatives in WSSV PCR brooder tests screening tests should be delayed until after spawning. We also recommend, with our PCR detection system, discarding all egg batches from brooders that are 1-step PCR positive after spawning. On the other hand, it may be possible with appropriate monitoring to use eggs from 2-step PCR positive brooders for production of WSSV-free or lightly infected postlarvae. These may be used to stock shrimp ponds under low-stress rearing conditions.

Animals↗