Biomedical subjects

C J Chang

Publications and source records attributed to C J Chang.

At least 37 records · Page 2Linked to original sources

PubMed2001

Physiologic analysis of cardiac cycle in an implantable impeller centrifugal left ventricular assist device.

The purpose of this study was to determine the physiologic relationship between the cardiac cycle and the nonpulsatile impeller centrifugal Taita No.1 left ventricular assist device (T-LVAD) in a chronic animal study. The relationship of the cardiac cycle, pump flow, aortic pressure, left ventricle pressure, and pump power were analyzed by 5 phases in 4 stages. The isovolumetric ventricular phase is from mitral valve closure (MVC) to aortic valve opening (AVO) and is called Stage 1. The ejection phase is from AVO to aortic valve closure (AVC) and is called Stage 2. The isovolumetric relaxation phase is from AVC to MVC and is called Stage 3. The passive filling and atrial contraction phase is from MVC to mitral valve opening (MVO) and called Stage 4. Based on evidence from the physiologic volume change of the left ventricle, the change of pump flow of the T-LVAD in a cardiac cycle by variable voltages of pump control was evaluated using animal models. After left posteriolateral thoracotomy via the fifth intercostal space under general anesthesia, the nonpulsatile centrifugal T-LVAD was implanted into 2 healthy calves. The inflow of the T-LVAD was inserted into the left ventricle through the mitral valve via the left atrial appendage. The arterial blood pressure waveform was measured and recorded on the outflow of the T-LVAD. The 4 phases of a cardiac cycle were defined as MVC-AVO (Stage 1), AVO-AVC (Stage 2), AVC-MVO (Stage 3) and MVC-MVO (Stage 4) according to the outflow pressure of the outflow of the T-LVAD and differential pressure between the outflow and inflow of the T-LVAD. We carried out the real-time waveform measurement for electrocardiogram, the outflow pressure, the T-LVAD flow and the speed, as well as open loop and constant voltage (V). In a cardiac cycle, the sensing current of the T-LVAD was inverse to the speed. The flow of the T-LVAD at the 4 stages was measured individually and analyzed with different control voltages from 10 to 18 V. The highest flow ratio of MVC-AVC/AVC-MVC was noted when the T-LVAD worked on 14 V. By using analysis methodology of the flow ratio of a cardiac cycle, the optimal physiologically effective control of the T-LVAD might be achieved.

Animals↗

PubMed2001

Delayed tear clearance in contact lens associated papillary conjunctivitis.

PURPOSE: To study the tear film clearance in contact lens associated papillary conjunctivitis patients. METHODS: Fifty-eight daily-wear soft contact lens wearers completed a questionnaire regarding a survey of their contact lens usage and subjective symptoms. They were grouped according to the size of conjunctival papillae, namely PC1 with no papillae, PC2 with papillae of less than 0.3 mm, and PC3 with papillae of 0.3-1.0 mm in diameter. Tear film breakup time and fluorescein clearance tests were performed. RESULTS: There was a median of 1, 2, and 3 subjective symptoms in PC1, PC2, and PC3 groups respectively (p < 0.001). Patients with larger papillae on their upper tarsus had more subjective symptoms such as burning sensation, discharge, limbal injection, foreign body sensation and dryness sensation (p = 0.018, 0.001, 0.004, 0.005, and 0.036 respectively). They also had shorter tear film breakup time (p = 0.05), delayed tear clearance (p = 0.002) and more corneal neovascularization (p < 0.001). Patients having delayed tear clearance test tended to have more subjective symptoms (p = 0.004) and larger papillae on upper tarsus (p = 0.002). However, neither the way the patients cleaned their contact lenses nor their enzyme cleaning frequency associated with the tear fluorescein clearance (p = 0.528 and 0.394, respectively). Meibomian gland dysfunction and corneal neovascularization did not correlate with the delayed tear clearance either (p = 0.111 and 0.717, respectively). CONCLUSIONS: Tear clearance in contact lens associated papillary conjunctivitis patients was delayed. We proposed that delayed tear clearance might increase the protein and inflammatory mediator concentrations in the tear film and contribute to the pathogenesis or aggravate the severity of contact lens associated papillary conjunctivitis.

Adult↗

PubMed2001

The heterogeneous nuclear ribonucleoprotein K (hnRNP K) interacts with dengue virus core protein.

Heterogeneous nuclear ribonucleoprotein K (hnRNP K), a component of hnRNP particles, is involved in several steps of gene expression regulation. Dengue (DEN) virus, a member of the Flaviviridae, is the primary cause of illnesses such as dengue fever, dengue hemorrhagic fever, and dengue shock syndrome. In mature DEN virus particles, the core protein is a structural protein that forms a nucleocapsid complex with genomic RNA. Very little of its biologic functions is known. Here, using an in vitro binding assay and coimmunoprecipitation analysis, we report a protein-protein interaction between the DEN virus core protein and hnRNP K. The C-terminal hydrophilic region of the DEN virus core protein, spanning amino acid residues 73 to 100, is required for such interaction. Results of glutathione-S transferase binding assays indicated that the core protein-hnRNP K interaction might be abolished in the presence of hnRNP K cognate nucleic acids. Furthermore, in a cotransfection experiment, the repressive effect of hnRNP K on C/EBPbeta-mediated transcription activation could be reversed by full-length DEN virus core protein but not by a truncated form containing amino acids 1-72. Our results suggest that, on DEN virus infection, the multiple functions of cellular hnRNP K may be affected by the virus core protein.

Amino Acid Sequence↗

PubMed2001

The changes of vitreous pH values in an acute glaucoma rabbit model.

The changes of vitreous pH values under acute glaucoma status have never been reported. In this study, we measured the changes of vitreous pH values in an acute glaucoma rabbit model. Under ketamine and xylazine anesthesia, the anterior chamber of the right eye of New Zealand white rabbits was cannulated and connected to a polygraph for continuous intraocular pressure (IOP) monitoring and a mini-pump for persistent injection of viscoelastic substance, Healon GV. The measurement of vitreous pH was done by inserting a pH probe via a third opening through the sclera into the vitreous. Different IOP levels were maintained by varied amounts of Healon GV injections into the anterior chamber. The changes of vitreous pH values following the intracameral injections were recorded and evaluated. The changes of vitreous pH values were minimal when IOPs were maintained at lower than 35 mmHg. Vitreous pH values decreased significantly from 7.32 to less than 7.03, when the IOPs were kept at 70 mmHg or higher. However, the decrease of pH values was reversible if IOP was held at 70 mmHg for less than 10 minutes and then reduced to normal level at once. In addition, with MTT viability assay, it was noted that the decrease in vitreous pH was associated with a higher percentage of retinal cell death.

Acidosis↗

PubMed2001

Sex differences of body fat distribution and cardiovascular dysmetabolic factors in old age.

BACKGROUND: The relationship between sexual differences of body fat distribution and cardiovascular dysmetabolic factors in old people is controversial. OBJECTIVES: To use centrality index-derived body fat distribution to clarify its relationship with glucose tolerance status, blood pressure and lipid profile. DESIGN: Cross-sectional survey in a tertiary-care medical centre in Tainan, Taiwan. SUBJECTS: 114 men and 101 women, aged > or = 60 years. METHODS: We measured total % body fat and body fat distribution (reflected as centrality index) by dual energy x-ray absorptiometry, and plasma glucose, glycosylated haemoglobin, blood pressure, total cholesterol, triglyceride, high-density lipoprotein (HDL) cholesterol and atherogenic index (total cholesterol/HDL cholesterol). RESULTS: Centrality index showed better linear correlation with cardiovascular dysmetabolic factors than body mass index, total % body fat and waist-to-hip ratio, except in systolic blood pressure. Women had higher total % body fat, but the % abdominal fat and centrality index were both higher in men. Subjects with diabetes mellitus had the highest centrality index compared with those with impaired or normal glucose tolerance. After adjustment for age and total % body fat, men still had higher diastolic blood pressure, triglyceride levels and atherogenic indices, but lower HDL cholesterol levels than women. However, when further adjusted for centrality index, the sex differences in cardiovascular dysmetabolic factors were statistically insignificant. CONCLUSIONS: Centrality index is a useful method for assessing body fat distribution in older people. Body fat distribution is an important factor in sex differences of cardiovascular dysmetabolic factors in old people.

Aged↗

PubMed2001

Cryogen spray cooling and pulsed dye laser treatment of cutaneous hemangiomas.

When a cryogen spurt is applied to the skin surface for tens of milliseconds, cooling remains localized in the epidermis, leaving the temperature of deeper hemangioma vessels unchanged. The objective of this study was to compare the efficacy and safety of noncooled laser treatment (NC-LT) vs. cryogen spray cooling plus laser treatment (CSC-LT) for cutaneous hemangiomas in a large series of patients. A retrospective review was conducted of 164 patients treated with the pulsed dye laser (lambda = 585 nm; taurho = 450 microsec) over an 8-year period. Eighty-two patients received NC-LT using light doses of 5.5 to 8 J per square centimeter. Subsequently, 82 patients received CSC-LT using light doses of 9 to 10 J per square centimeter. The primary efficacy measure was quantitative assessment of improvements in lesional volume, texture, and color. Safety was evaluated for each treatment group by monitoring for adverse effects. Based on chi-squared analysis, there were clinical and significant differences in the number of treatments (p = 0.001), and improvement in volume (p = 0.008) and texture (p = 0.001) of the CSC-LT group compared with the NC-LT group. Permanent adverse effects were not observed in either group. In conclusion, CSC permitted the use of higher incident light doses for treatment of cutaneous hemangiomas, resulting in fewer treatments required and better improvement in lesional volume and texture.

Adolescent↗

PubMed2001

Potential complications of intralesional laser photocoagulation for extensive vascular malformations.

Vascular anomalies remain a challenge for both patients and plastic surgeons. Recently, promising results have been reported using intralesional photocoagulation (ILP) to treat extensive vascular lesions. At the authors' center, they have treated more than 300 patients with vascular anomalies in different parts of the body between 1996 and 1999. They describe their operative techniques of ILP. Laser pulses of a 1,064-nm wavelength from the Nd:YAG laser were delivered to the target tissues with a 600-microm optical fiber. They report 2 patients who developed complications after a single session of ILP therapy for their extensive vascular malformations. The first patient had Klippel-Trenaunay syndrome (capillary-lymphaticovenous malformations) with widespread involvement of her buttocks and left lower limb. She had severe leukocytosis, thrombocytosis, and hyperkalemia that resolved with intravenous hydration, antibiotics, and sodium bicarbonate. In their second patient, the entire left upper limb was affected. Her total red cell count diminished by a quarter and her hemoglobin concentration dropped by more than 3 g%. This was corrected gradually with supplemental oral hematinics. Although these complications resolved uneventfully in their patients, they hope that their possible development will caution anyone who may wish to attempt this new method of therapy.

Adult↗

PubMed2001

ECG data compression using truncated singular value decomposition.

The method of truncated singular value decomposition (SVD) is proposed for electrocardiogram (ECG) data compression. The signal decomposition capability of SVD is exploited to extract the significant feature components of the ECG by decomposing the ECG into a set of basic patterns with associated scaling factors. The signal informations are mostly concentrated within a certain number of singular values with related singular vectors due to the strong interbeat correlation among ECG cycles. Therefore, only the relevant parts of the singular triplets need to be retained as the compressed data for retrieving the original signals. The insignificant overhead can be truncated to eliminate the redundancy of ECG data compression. The Massachusetts Institute of Technology-Beth Israel Hospital arrhythmia database was applied to evaluate the compression performance and recoverability in the retrieved ECG signals. The approximate achievement was presented with an average data rate of 143.2 b/s with a relatively low reconstructed error. These results showed that truncated SVD method can provide an efficient coding with high-compression ratios. The computational efficiency of the SVD method in comparing with other techniques demonstrated the method as an effective technique for ECG data storage or signals transmission. Index Terms-Data compression, electrocardiogram, feature extraction, quasi-periodic signal, singular value decomposition.

Algorithms↗

PubMed2001

The C677T mutation of the methylenetetrahydrofolate reductase gene is not associated with the risk of coronary artery disease or venous thrombosis among Chinese in Taiwan.

OBJECTIVES: We sought to investigate the association between the methylenetetrahydrofolate reductase (MTHFR) gene C677T mutation and the risk of coronary artery disease (CAD), myocardial infarction (MI) and venous thrombosis (VT) in a Chinese population in Taiwan. METHODS: The subjects included 218 CAD patients, 107 VT patients, and their age- and sex-matched controls. DNA was extracted from the blood and genotypes were determined by polymerase chain reaction, restriction mapping with HinfI and gel electrophoresis. RESULTS: The distribution of MTHFR genotypes was similar in the CAD cases and controls; the genotype TT was present in 6.0% of CAD patients, as compared to 6.9% of CAD control subjects (p = 0.165; odds ratio = 0. 86; 95% confidence interval = 0.40-1.85). The frequency of the T allele was also similar in CAD cases and controls (25.5% vs. 24.8%; p = 0.788). There was no significant association between TT homozygosity and the risk of MI. The genotype distributions and the frequency of the T allele were also similar in VT cases and controls. CONCLUSIONS: Our data suggest that there is no association between the C677T mutation of the human MTHFR gene and the risk of CAD or VT among Chinese in Taiwan.

Alleles↗

PubMed2001

Cross-cultural implementation of a Chinese version of the Schedules for Clinical Assessment in Neuropsychiatry (SCAN) in Taiwan.

BACKGROUND: There are no published reports of cross-cultural equivalence and interrater reliability at the level of individual symptom items assessed by a semi-structured clinical interview employing operationalised clinician ratings. AIMS: To assess the cross-cultural clinical equivalence and reliability of a Chinese version of the World Health Organization Schedules for Clinical Assessment in Neuropsychiatry (SCAN). METHOD: UK-US and Taiwanese groups of psychiatrists used Chinese and English transcripts of videotape interviews of Taiwanese patients to discuss cross-cultural issues and ratings of SCAN items. Item ratings were compared quantitatively individually and pooled by SCAN section. RESULTS: Chinese equivalents were found for all SCAN items. No between-group differences were found for most individual items, but there were differences for some scaled items. Average agreement between the two groups was 69-100%. CONCLUSIONS: Cross-cultural implementation based on SCAN in Taiwan appears valid.

China↗

PubMed2001

Plasma glucose-lowering effect of tramadol in streptozotocin-induced diabetic rats.

The effect of tramadol on the plasma glucose level of streptozotocin (STZ)-induced diabetic rats was investigated. A dose-dependent lowering of plasma glucose was seen in the fasting STZ-induced diabetic rats 30 min after intravenous injection of tramadol. This effect of tramadol was abolished by pretreatment with naloxone or naloxonazine at doses sufficient to block opioid mu-receptors. However, response to tramadol was not changed in STZ-induced diabetic rats receiving p-chlorophenylalanine at a dose sufficient to deplete endogenous 5-hydroxytrptamine (5-HT). Therefore, mediation of 5-HT in this action of tramadol is ruled out. In isolated soleus muscle, tramadol enhanced the uptake of radioactive glucose in a concentration-dependent manner. The stimulatory effects of tramadol on glycogen synthesis were also seen in hepatocytes isolated from STZ-induced diabetic rats. The blockade of these actions by naloxone and naloxonazine indicated the mediation of opioid mu-receptors. The mRNA and protein levels of the subtype 4 form of glucose transporter in soleus muscle were increased after repeated treatments for 4 days with tramadol in STZ-induced diabetic rats. Moreover, similar repeated treatments with tramadol reversed the elevated mRNA and protein levels of phosphoenolpyruvate carboxykinase in the liver of STZ-induced diabetic rats. These results suggest that activation of opioid mu-receptors by tramadol can increase the utilization of glucose and/or decrease hepatic gluconeogenesis to lower plasma glucose in diabetic rats lacking insulin.

Animals↗

PubMed2001

Cryogen spray cooling in conjunction with pulse dye laser treatment of port wine stains of the head and neck.

BACKGROUND: When a cryogen spurt is applied to the skin surface for an appropriately short period of time, the spatial distribution of cooling remains localized in the normal overlying epidermis, while leaving the temperature of deeper port wine stain (PWS) blood vessels unchanged. Furthermore, cooling continues after pulsed laser exposure as cryogen remaining on the surface evaporates and removes heat deposited by light absorption in epidermal melanin. The objective of this study was to evaluate the efficacy and advantages of cryogen spray cooling plus flashlamp-pumping in conjunction with dye laser treatment (CSC-LT) of PWS. METHODS: From 1996 to 2000, a retrospective study was conducted on 63 patients, consisting of 43 women and 20 men, between the ages of 8 and 62 years treated with pulsed dye laser (lambda = 585 nm, tau p = 450 microseconds) over a 4-year period. The duration of cryogen spurts and the delay period between cryogen delivery and laser illumination were controlled. An infrared focal plane array thermodetector measured changes of lesion surface temperature which were recorded. The subject was asked to score discomfort during treatment using a pain scale. The primary efficacy measure was the quantitative assessment of a blanching response score. RESULTS: The ambient skin surface temperature of PWS was 33.31 +/- 1.55 degrees C. The mean pain score for uncooled sites was 39.85 +/- 0.23 compared to 20.18 +/- 0.15 for cooled sites. There was a statistically significant difference in pain elimination between cooled and uncooled sites (p = 0.001). The mean blanching response score of CSC-LT was 3.70. A significant blanching response of PWS when receiving CSC-LT was noted. CONCLUSION: Our clinical studies demonstrate the feasibility of selective epidermal cooling while achieving photothermolysis of blood vessels during pulsed dye laser treatment of PWS.

Adolescent↗

PubMed2001

Lethality of standard total parenteral nutrition following major liver resection in rats is prevented by high arginine and high branched chain amino acids but not by glutamine.

Standard total parenteral nutrition (TPN), with or without fat, in amounts approximating the ad libitum intake of normal rats is highly lethal for rats following 70% hepatectomy. Because of significant metabolic changes including alterations of branched chain amino acids (BCAA), arginine (ARG), and glutamine (GLN) associated with serious injury, sepsis, and liver dysfunction, we hypothesized that (1) increasing concentrations of BCAA and ARG in TPN and (2) including glutamine in the TPN may diminish the lethality. Male Sprague-Dawley rats with 70% hepatectomy and jugular vein catheterization were divided into groups. Two sets of experiments were conducted. In Experiment 1, the effects of varying concentrations of BCAA and ARG in the TPN infusate, singly and together, were assessed: Group 1, Standard TPN (19% BCAA, 4.8 g ARG/L); Group II, High BCAA TPN (35% BCAA, 4.8 g ARG/L); Group III, High ARG TPN (19% BCAA, 9.6 g ARG/L); Group IV, High ARG, High BCAA TPN (35% BCAA, 9.6 g ARG/L; Group V, chow and tap water ad libitum. In experiment 2, the effect of 2% GLN in TPN was evaluated: Group A, Standard TPN and Group B, 2% GLN TPN. All infusates were isocaloric (216 Kcal/Kg/d) and isonitrogenous (1.94 g N/Kg/d) delivered at half concentration on postoperative day 1, 3/4 concentration on postoperative day 2, and at full concentration thereafter. Experiment 1: Thirty-three to 36% of rats in Groups I (Standard TPN) (4/11), II (High BCAA TPN) (4/11) and III (High ARG TPN) (4/12) died within 6 days. In sharp contrast, none died in Groups IV (High BCAA, High ARG TPN) and V (rat chow and tap water) (P < 0.05 in each comparison). Among rats in the 4 TPN groups surviving 7 days, there were no significant differences in body weight change (minus 3-4%), spleen or lung weight, extent of liver regeneration (61-66%). Serum total protein and albumin were significantly higher in Group V (chow-fed) (similar to values in normal rats) than in Groups I-IV, P < 0.05 in each case. Serum total bilirubin was significantly higher in Group I than in normals and in Groups II, III, and V. Serum lactate dehydrogenase levels were similar in normals and all 5 groups. Serum aspartate amino transferase level was higher in Group I than in normals but not significantly different from those groups II-V; the latter were similar to normals. Experiment 2: Thirty percent of rats in Groups A (Standard TPN) (3/10) and B (GLN TPN) (3/10) died within 6 days. Among rats surviving for 7 days, body weight change (minus 3-5%), liver regeneration (67-70%), and liver tests were similar in both groups. TPN modified to contain high concentrations of both BCAA and ARG (but not of either alone) prevented the high frequency of lethality induced by standard TPN in rats with 70% hepatectomy. No such salutary effect was shown by modifying the TPN to contain 2% GLN. The striking benefit observed when TPN containing high BCAA and high ARG was infused may be due to the high BCAA leading toward normalization of serum amino acid levels, reducing proteolysis, increasing protein synthesis, and accelerating early liver regeneration, combined with the high ARG likely reducing serum ammonia and leading to increased host defense, and perhaps, thereby, preventing bacterial translocation and bacteremia.

Amino Acids, Branched-Chain↗

PubMed2000

Insulin restores neuronal nitric oxide synthase expression in streptozotocin-induced diabetic rats.

Nitric oxide (NO) is known to play an important role in the pathophysiology of insulin-dependent diabetic mellitus (IDDM). In an attempt to investigate the relation between insulin and NO in IDDM, the present study employed male Wistar rats to induce IDDM by intravenous injection of streptozotocin (STZ). Four groups of rats were used; untreated normal control group, insulin treated STZ group, vehicle-treated STZ control, and one group of age-matched rats which were orally supplied with glucose to increase plasma glucose (glucose-challenged rats). Changes of the activity and gene expression of neuronal nitric oxide synthase (nNOS) were examined in cerebellum and kidney of these groups. The activity of nNOS in cerebellum, determined by conversion of [3H] L-arginine to [3H] L-citrulline, in STZ-induced diabetic rats was markedly lower than normal rats. Insulin treatment reversed the nNOS activity. Similar reversion by insulin treatment was also obtained in the gene expression of nNOS. However, the activity and gene expression of nNOS in glucose-challenged rats were not different from those in normal rats. The role of hyperglycemia can thus be ruled out. These findings indicated that an impairment of nNOS in the brain of rats with IDDM is mainly due to the absence of insulin.

Animals↗

PubMed2000

Xanthene-bridged cofacial bisporphyrins.

The synthesis and characterization of cofacial bisporphyrins juxtaposed by xanthene-bridged pillars are presented. The one-pot preparation of the xanthene dialdehyde avoids the lengthy bridge synthesis accompanying other cofacial porphyrin systems, thus allowing for the facile preparation of homobimetallic zinc (10), copper (11), and nickel (12) complexes. The cofacial orientation of the two porphyrin macrocycles was confirmed by X-ray crystallography. Structural data are provided for bisporphyrins 10-12: 10 (C79H82N8OZn2), triclinic, space group P1, a = 11.2671(2) A, b = 14.9809(2) A, c = 20.4852(2) A, alpha = 101.6680(10) degrees, beta = 100.8890(10) degrees, gamma = 101.8060(10) degrees, Z = 2; 11 (C79H82N8OCu2), triclinic, space group P1, a = 11.21410(10) A, b = 14.9539(5) A, c = 20.6915(7) A, alpha = 101.810(2) degrees, beta = 101.044(2) degrees, gamma = 101.722(2) degrees, Z = 2; 12 (C79H82N8ONi2), monoclinic, space group C2/c, a = 24.1671(4) A, b = 10.669 A, c = 50.5080(9) A, beta = 99.553(2) degrees, Z = 8. Exciton interactions between the porphyrin rings are apparent in electronic spectra, consistent with the cofacial superstructure. The combination of structural and spectroscopic data provides a basis for the design of additional metal derivatives for the activation of dioxygen and other small molecules.

Bridged-Ring Compounds↗

PubMed2000

Use of 16S rDNA sequences as signature characters to identify Xylella fastidiosa.

The nucleotide sequences of 16S rDNAs (coding for the small subunit ribosomal RNAs) were used to identify Xylella fastidiosa, a nutritionally fastidious plant pathogenic bacterium. The near-complete 16S rDNAs from nine strains of Xyl. fastidiosa, including seven pathotypes and one strain of Xanthomonas campestris pv. campestris, were amplified through PCR with two conserved primers (forward primer 5'-AGA GTT TGA TCC TGG CTC AG-3' and reverse primer 5'-AAG GAG GTG ATC CAG CC-3') and sequenced. The 16S sequences were compared with all eukaryote and prokaryote DNA entries in GenBank database. A Xyl. fastidiosa 16S rDNA sequence, M26601, was determined to be the most similar to all the near-complete (1537 bp) and partial 5' end sequences from Xyl. fastidiosa, but not those from the Xanthomonas strain. A 20-bp oligonucleotide (5'-TTG GTA GTA ATA CCA TGG GT-3') was found to be highly characteristic of Xyl. fastidiosa. Since the 16S rDNA of Xyl. fastidiosa strains are highly homologous and characteristically different from other bacteria, including the most closely related Xanthomonas, 16S rDNA sequences can be used as signature characters to identify this bacterium.

Base Sequence↗

PubMed2000

Cytotoxicity of extractives from Taiwania cryptomerioides heartwood.

The cytotoxicity of the dominant lignans and sesquiterpenoids from Taiwania (Taiwania cryptomerioides Hayata) was investigated. Three human tumor cells including A-549 lung carcinoma. MCF-7 breast adenocarcinoma and HT-29 colon adenocarcinoma were selected to illustrate the structure-cytotoxicity relationships of Taiwania's dominant compounds. Taiwanin A, taiwanin E and dimethylmatairesinol exhibited significant cytotoxicity against three human tumor cells. Among them, taiwanin A possesses the strongest cytotoxic activity. In addition, the morphology-based evaluation, flow cytometric analysis, and DNA fragmentation assays demonstrated that the tumor cell death induced by taiwanin A was due to apoptosis.

Antineoplastic Agents, Phytogenic↗

PubMed2000

16S rDNA sequence analysis of Xylella fastidiosa strains.

The 16S rDNA encoding the small subunit ribosomal RNA were amplified by PCR, cloned, and sequenced from 16 strains of Xylella fastidiosa originating from nine different hosts. In pair-wise comparisons, X. fastidiosa strains showed a maximum variation of 1.0% or 14 nucleotide positions. When all 16 sequences were considered as a set, 54 variable positions were found. Analysis of the sequence data indicated that the X. fastdiosa strains formed three rDNA groups. Group one includes Pierce's disease and mulberry leaf scorch strains; Group two, periwinkle wilt, plum leaf scald, phony peach, oak leaf scorch, and elm leaf scorch strains; and Group three, citrus variegated chlorosis and coffee leaf scorch strains. All X. fastidiosa strains exhibited significantly higher levels of sequence heterogeneity (63 to 83 nucleotide positions) when compared to species from Xanthomonas and Stenotrophomonas. Our data demonstrate that 16S rDNA sequence data could provide valuable information for future classification of X. fastidiosa at the sub-species level.

DNA, Ribosomal↗