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Biomedical subjects

C Y Lee

Publications and source records attributed to C Y Lee.

At least 91 records · Page 5Linked to original sources
PubMed2000

Slow rise of Ca2+ and slow release of reactive oxygen species are two cross-talked events important in tumour necrosis factor-alpha-mediated apoptosis.

Tumour necrosis factor-alpha (TNF-alpha) was found to be a cell cycle-independent apoptogenic cytokine in cultured fibroblast L929 cells. This assertion is based on the observations (1) TNF-alpha increased the number of cells with hypo-diploid DNA in a time dependent manner as revealed by flow cytometry, and (2) TNF-alpha induced DNA fragmentation as resolved by agarose gel electrophoresis. When cells were exposed to TNF-alpha (50 ng/ml), a slow rise in intracellular free Ca2+ level and a delayed increase in the production of reactive oxygen species (ROS) (both observed 3 h after the addition of TNF-alpha) were observed in fluo-3 and fura-red or dichlorofluorescein loaded cells, respectively. Interestingly, challenge of cells with TNF-alpha in the presence of BAPTA/AM, an intracellular Ca2+ chelator, decreased the release of ROS. Removal of ROS by 4-hydroxy 2,2,6,6-tetra-methyl-piperidinooxy (4OH-TEMPO) blocked the TNF-alpha-mediated Ca2+ rise. Moreover, when cells were exposed to TNF-alpha with both 4OH-TEMPO and BAPTA/AM, more viable cells were found than from treatment with either BAPTA/AM or 4OH-TEMPO. These results suggest that ROS and cellular Ca2+ are two cross-talk messengers important in TNF-alpha-mediated apoptosis.

Animals↗
PubMed2000

Spermatid-specific expression of the novel X-linked gene product SPAN-X localized to the nucleus of human spermatozoa.

Formation of mature spermatozoa involves a series of dramatic molecular and morphological changes in the male germ cell lineage. These changes result from the temporally regulated transcription and translation of several testis-specific gene products. Here, we describe a novel, testis-specific protein designated SPAN-X for sperm protein associated with the nucleus on the X chromosome. SPAN-X sequences showed no significant similarity with known cDNA or peptide sequences. The SPAN-X peptide sequences contained three overlapping consensus nuclear localization signals, a high percentage (33%-37%) of charged amino acid residues, and a relatively acidic isoelectric point (pI; 4.88-6.05). Northern analysis of mRNA from multiple human tissues identified a SPAN-X transcript exclusively in the testis. In situ hybridization of human testes sections showed SPAN-X mRNA expression in haploid, round, and elongating spermatids. The SPANX gene was mapped to chromosome Xq27. 1 by fluorescence in situ hybridization and by Southern blot analysis of human/mouse somatic cell hybrids. On Western blots of human sperm proteins, antirecombinant SPAN-X antibodies reacted with broad bands migrating between 15-20 kDa. Immunofluorescent labeling of human spermatozoa demonstrated SPAN-X localization to nuclear craters and cytoplasmic droplets. Expression of SPAN-X, an X-linked gene product, exclusively in haploid spermatids leads to interesting questions regarding the transcription of sex-linked genes during spermiogenesis.

Amino Acid Sequence↗
PubMed2000

Vitamin E supplementation improves cell-mediated immunity and oxidative stress of Asian men and women.

Vitamin E is an efficient antioxidant and a modulator of the immune system. Although racial differences in both baseline vitamin E level and immunologic subsets are known, no reliable data exist for the Asian population. Furthermore, the extent of the effect of alpha-tocopherol in protecting lymphocyte cells against oxidative stress and its association with cell-mediated immunity have not been elucidated. This study was undertaken to investigate the immunologic and antioxidant effects of vitamin E in healthy ethnic Chinese men and women. Volunteers < 35 y old (n = 26) were supplemented with 233 mg/d dl-alpha-tocopherol for 28 d. The in vitro proliferative response to phytohemagglutinin (PHA) or lipopolysaccharide (LPS) of T-lymphocytes was determined in the study group before and after vitamin E supplementation. Cell-mediated immunity subsets and hydrogen peroxide production in T-lymphocytes were investigated by flow cytometry. The oxidant-antioxidant balance in plasma and urine was studied by spectrophotometric and gas chromatography-mass selective detection methods. The antioxidant properties of vitamin E were established (P: < 0.01) by the elevation of plasma vitamin E, together with depression in both plasma malondialdehyde and urinary DNA adduct 8-hydroxy-2'-deoxyguanosine after supplementation. Our data suggest a specific requirement for vitamin E in total-T and T-helper cell proliferation. We present the first evidence of the beneficial effects of supplemental vitamin E in healthy Chinese individuals on cell-mediated immunity and oxidative stress.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2000

Molecular epidemiology and association of putative pathogens in root canal infection.

The purpose of this study was to investigate the epidemiology of putative pathogens in root canals with apical periodontitis and to determine the associations among the putative pathogens. Eighteen symptomatic and 20 asymptomatic teeth from 36 subjects were studied. This research was performed with polymerase chain reaction and hybridization using rRNA-based oligonucleotide probes. The most frequently found species was Fusobacterium sp. (68.4%), followed by Peptostreptococcus micros (44.7%) and Porphyromonas gingivalis (26.3%). Sixteen teeth (42.1%) contained one or more species of the selected black-pigmented bacteria. Bacteroides forsythus and Treponema sp. were detected in 8 teeth and 6 teeth, respectively. Among the analyzed bacteria, significant relationships were shown in the combination of B. forsythus/P. gingivalis and Treponema sp./P. gingivalis. There was no significant association between any bacteria and any symptoms.

Adolescent↗
PubMed2000

Metal content and biochemical analyses of a recombinant collagenase PrtV from Vibrio parahaemolyticus.

PrtV is an extracellular metalloprotease of Vibrio parahaemolyticus and regarded as a collagenase. Inductively coupled plasma-optical emission spectrometry analysis indicated that the recombinant PrtV contains 1 mol of zinc per mol of the native enzyme. On the basis of a kinetic study using 2-furanacryloyl-Leu-Gly-Pro-Ala (FALGPA, the specific substrate for bacterial collagenase) as a substrate, it was suggested that metal ions may play a significant role in the binding and catalytic steps of the substrate. PrtV hydrolyzed type I, II, III, and IV collagens; however, it did not hydrolyze type V. In addition, the hydrolysis of native proteins and synthetic substrates revealed that PrtV possesses higher activity toward collagen and collagen-like sequences. The result of the thermal stability study indicated that PrtV was thermostable up to 40 C; at 50 C, stability gradually decreased. In addition, PrtV showed higher storage stability at -20 and 4 C, respectively, than at 25 C. Compared with collagenases from Clostridium histolyticum and Vibrio alginolyticus, PrtV was immunologically different and had no significant effect on the growth of CHO, HeLa, and Vero cells. Taken together, the results of the studies described in this paper advance our knowledge concerning the metal content and biochemical properties of PrtV.

Animals↗
PubMed2000

Immunoidentification of gonadotropin releasing hormone receptor in human sperm, pituitary and cancer cells.

PROBLEM: To generate monoclonal antibodies specific to the receptor of gonadotropin releasing hormone (GnRH) for immunoidentification of the GnRH receptor (RGnRH) in human sperm, pituitary and cancer cells. METHODS: Four oligopeptides corresponding to RGnRH amino acid residues 1-29, 182-193, 195-206 and 293-306 in the extracellular domains were synthesized, conjugated to hemocyanin from Keyhole Limpet and used as immunogens to generate specific monoclonal antibodies. Enzyme-linked immunosorbent assay was used for initial screening of hybridomas. RESULTS: A total of 15 hybrid cell lines secreting RGnRH-specific monoclonal antibodies were initially established. By using some of these monoclonal antibodies as immunohistochemical probes, RGnRH was localized in the acrosomal region of human sperm, in the anterior pituitary tissue and in cancer cells of human ovarian and cervical origins. RGnRH was shown to have a molecular size of 45,000 +/- 5,000 kDa by Western blot assay. Expression of RGnRH mRNA in several human tissues and cancer cells was established by the reverse transcriptase-polymerase chain reaction method. CONCLUSION: RGnRH-specific monoclonal antibodies may be a valuable tool of identifying the presence of RGnRH in various normal and malignant human tissues.

Antibodies, Monoclonal↗
PubMed2000

Bacteremic pneumonia caused by a single clone of Streptococcus pneumoniae with different optochin susceptibilities.

Two isolates of Streptococcus pneumoniae having different optochin susceptibilities were recovered from a blood sample of a 2-year-old boy with community-acquired pneumonia. The two isolates were documented to belong to a single clone on the basis of the isolates' identical serotype (23F), antibiograms by the E-test, random amplified polymorphic DNA patterns generated by arbitrarily primed PCR, pulsed-field gel electrophoresis, and restriction fragment length polymorphism of the penicillin-binding protein genes pbp2b and pbp2x.

Bacteremia↗
PubMed2000

NSP4 gene analysis of rotaviruses recovered from infected children with and without diarrhea.

The transmembrane glycoprotein NSP4 functions as a viral enterotoxin capable of inducing diarrhea in young mice. It has been suggested that NSP4 may be a key determinant of rotavirus pathogenicity and a target for vaccine development. Twenty two G1P[6] rotaviruses from babies with and without diarrhea were comparatively analyzed along with reference strains and another 22 Taiwanese human rotaviruses of G and P combination types different from the G1P[6] type. The sequence variations in the NSP4 genes were studied by direct sequencing analysis of the amplicons of reverse transcription-PCR. Two genetic groups could be identified in this analysis. While the majority of these strains were closely related to the Wa strain, the G2 viruses were closely related to the S2 strain. Furthermore, phylogenetic analysis of the NSP4 gene among the G2 rotaviruses revealed three distinct lineages associated with DS-1, S2, and E210, respectively, as has been reported previously for the VP7 gene. However, we found no apparent correlation in the deduced amino acid sequences corresponding to the proposed enterotoxic peptide region between the rotaviruses recovered from individuals with and without diarrhea. The NSP4 gene product being a pathogenic determinant may not be a generalized phenomenon.

Amino Acid Sequence↗
PubMed2000

Distension of urinary bladder induces exaggerated coronary constriction in smokers with early atherosclerosis.

Distension of the urinary bladder causes an increase in efferent sympathetic activity, which can precipitate myocardial ischemia. Smoking has been shown to modulate activities of afferent nerves from the distended urinary bladder and to impair endothelial function in response to sympathetic activation. To assess the effect of bladder distension on coronary dynamics in smokers, we measured epicardial and microvascular responses in 24 patients with early atherosclerosis (< 50% diameter stenosis). Patients were classified into habitual smokers (group 1, n = 14) and nonsmokers (group 2, n = 10). Habitual smokers were randomized into two subgroups on the basis of the use of doxazosin, as follows: subgroup 1A (n = 7), without administration of doxazosin before catheterization; subgroup 1B (n = 7), with dosing doxazosin. In response to bladder distension (mean intravesical pressure 21.5 mmHg), bladder distension significantly decreased coronary diameter at the stenotic segments, coronary blood flow, and increased coronary resistance compared with baseline values, in subgroup 1A patients. In subgroup 1B patients during bladder distension, coronary diameter, coronary blood flow, and coronary resistance did not show significant changes compared with baseline values. There were significant differences of coronary diameter at the stenotic segments, coronary blood flow, and of changes of coronary vascular resistance between subgroup 1A and group 2 during bladder distension, despite similar changes in rate-pressure product. The present study showed that urinary bladder distension caused an abnormal vasomotor response of epicardial vasoconstriction and a concomitant increased coronary resistance, which leads to reduction in coronary blood flow in patients with early atherosclerosis. Smoking may further impair the response, implying that smoking has exaggerated response to sympathetic stimulation of conduit and resistance vessels. The abnormal response was abolished by pretreated administration of doxazosin, suggesting that the involved mechanisms are related to alpha(1)-adrenoceptors.

Aged↗
PubMed2000

Minimization and management of wastes from biomedical research.

Several committees were established by the National Association of Physicians for the Environment to investigate and report on various topics at the National Leadership Conference on Biomedical Research and the Environment held at the 1--2 November 1999 at the National Institutes of Health in Bethesda, Maryland. This is the report of the Committee on Minimization and Management of Wastes from Biomedical Research. Biomedical research facilities contribute a small fraction of the total amount of wastes generated in the United States, and the rate of generation appears to be decreasing. Significant reductions in generation of hazardous, radioactive, and mixed wastes have recently been reported, even at facilities with rapidly expanding research programs. Changes in the focus of research, improvements in laboratory techniques, and greater emphasis on waste minimization (volume and toxicity reduction) explain the declining trend in generation. The potential for uncontrolled releases of wastes from biomedical research facilities and adverse impacts on the general environment from these wastes appears to be low. Wastes are subject to numerous regulatory requirements and are contained and managed in a manner protective of the environment. Most biohazardous agents, chemicals, and radionuclides that find significant use in research are not likely to be persistent, bioaccumulative, or toxic if they are released. Today, the primary motivations for the ongoing efforts by facilities to improve minimization and management of wastes are regulatory compliance and avoidance of the high disposal costs and liabilities associated with generation of regulated wastes. The committee concluded that there was no evidence suggesting that the anticipated increases in biomedical research will significantly increase generation of hazardous wastes or have adverse impacts on the general environment. This conclusion assumes the positive, countervailing trends of enhanced pollution prevention efforts by facilities and reductions in waste generation resulting from improvements in research methods will continue.

Biomedical Technology↗
PubMed2000

Amanita virosa induced toxic hepatitis: report of three cases.

We report here three cases of Amanita virosa induced toxic hepatitis. Two of the three cases recovered but the other died 10 days after mushroom ingestion. Since the mortality of Amanita mushroom induced toxic hepatitis is very high, prompt diagnosis and aggressive therapeutic measures should be initiated as soon as possible. Our cases showed that the initial serum aminotransferase levels might not predict the clinical outcome of the patient, but that the prothrombin time (PT) seemed to be a more useful prognostic marker. Close monitoring of aminotransferase levels and PT as well as appropriate therapy are recommended. All three cases showed signs of proteinuria and we were able to characterize mixed tubular and glomerular type proteinuria at 3 or 4 days after ingestion in two cases. Among the previously reported Korean cases of suspected Amanita induced toxic hepatitis, most species could not be identified except for four cases of Amanita virosa. No cases of Amanita phalloides induced toxic hepatitis have been identified in Korea so far.

Adult↗
PubMed2000

Geographical differences in human herpesvirus 8 seroepidemiology: a survey of 1,201 individuals in Asia.

Since the discovery of human herpesvirus 8 (HHV8) as a contributory cause of Kaposis sarcoma, the clinical role of this virus has been actively investigated. An understanding of HHV8 seroepidemiology is critical for the study of its pathogenesis within a specific environment. A sero-survey is described in Taiwan of 1,201 individuals ranging in age from under 1 year to over 70. Indirect immunofluorescence assay was used to determine antibody titers against both latent and lytic antigens of HHV8. The results indicate that very few individuals (3-4%) were exposed to HHV8 before 10 years of age. Infection rate peaked (19.2%) between the ages of 21 to 40. Females showed a slightly higher seroprevalence for HHV8 than males, but the difference was not statistically significant. Pregnancy did not correlate with increased HHV8 infection rate nor with augmented HHV8 antibody titers. It is concluded that HHV8 in Taiwan is predominantly an infectious agent for adults. In this geographical locale, HHV8 is similar to herpes simplex virus type 2 in its likely transmission occurring presumptively through sexual routes. However, the study also indicates that a smaller portion of HHV8-transmission could occur through nonsexual contacts.

Adolescent↗
PubMed2000

Protein-protein interaction of FHL2, a LIM domain protein preferentially expressed in human heart, with hCDC47.

In the yeast two-hybrid library screening, the heart-specific FHL2 protein was found to interact with hCDC47. In vitro interaction study between FHL2 protein and hCDC47 was demonstrated. From the results of domain studies by the yeast two-hybrid assay, the second and third LIM domains in conjunction with the first half LIM domain of FHL2 were identified to be important in binding with hCDC47. Besides, in Northern blot hybridization of human cancer cell lines, the highest FHL2 mRNA expression was detected in colorectal adenocarcinoma SW480 and HeLa cell S3. Our results imply that FHL2 protein may associate with cancer development and may act as a molecular adapter to form a multicomplex with hCDC47 in the nucleus, thus it plays an important role in the specification or maintenance of the terminal differentiated phenotype of heart muscle cells.

Base Sequence↗
PubMed2000

Short-term vestibular responses to repeated rotations.

To investigate the short-term vestibular habituation, we performed the 4 successive velocity step tests on 28 volunteers, the peak velocity of which was 100 deg/sec with acceleration and deceleration of 100 deg/sec2. As the repeated rotations might alter the vestibulo-ocular reflex (VOR), sinusoidal rotations at a frequency of 0.16 Hz were also given before and after the 4 successive velocity step tests to investigate the changes of gain and phase of VOR. The 28 volunteers were divided into two groups, group I and II, according to their responses to repeated rotations. In group I (25 subjects, mean age 23.7 year), the mean values of the slow cumulative eye position (SCEP), the time integral of eye velocity during nystagmus, was reduced after each trial of the 4-successive velocity step tests as follows; 403.4 +/- 29 degree (1st trial), 346.2 +/- 37 degree (2nd trial), 278.3 +/- 33 degree (3rd trial) and 256.6 +/- 36 degree (4th trial). The time constant of the nystagmus was also reduced as follows; 12.9 +/- 0.78 second (1st trial), 12 +/- 0.63 second (2nd trial), 9.7 +/- 0.78 second (3rd trial) and 9.9 +/- 0.54 second (4th trial). In group II (3 subjects, mean age 28.3 year), the mean values of SCEP gradually increased; 774.3 +/- 135 degree (1st trial), 1127 +/- 178 degree (2nd trial), 1096.3 +/- 123.4 degree (3rd trial) and 1225.7 +/- 199.7 degree (4th trial). The time constant of the nystagmus increased; 15.7 +/- 2.7 second (1st trial), 22 +/- 4.5 second (2nd trial), 22.3 +/- 3.3 second (3rd trial) and 23.3 +/- 5.7 second (4th trial). The gain of vestibulo-ocular reflex (VOR) induced by sinusoidal rotations at a frequency 0.16 Hz increased in both groups: 0.59 +/- 0.03 to 0.78 +/- 0.06 (group I) and 0.65 +/- 0.07 to 1.15 +/- 0.06 (group II). Phase changes were also observed. In group I, the phase was shifted from 0.6 +/- 0.6 degree to -0.40 +/- 0.6 degree. In group II, the phase was shifted from 3.67 +/- 1.86 degree to -0.33 +/- 0.33 degree. The repeated rotation did not induce a common nystagmic response in all subjects. Thus, person to person variations should be considered in short term vestibular habituation.

Adult↗
PubMed2000

Pertussis seroepidemiology in Taipei.

PURPOSE: We evaluated the seroprevalence of pertussis among apparently healthy Taipei residents. METHODS: From January 1992 through December 1994, we recruited subjects from a well baby clinic (children < 3 years), kindergartens, primary, and secondary schools and colleges (3-20 years), a health exam clinic (> 20 years), and obstetric clinics (pregnant women). Subjects were stratified into 12 groups according to age and pregnant women were considered separately. The serum antibody titers against filamentous hemagglutinin (FHA) and pertussis toxin (PT) were measured by enzyme-linked immunosorbent assay. RESULTS: The anti-PT and anti-FHA titers were elevated in the 4 to 6-month and 19 to 20-month age groups, coinciding with regular pertussis vaccinations. The anti-PT titers rose again in the 3 to 4-year age group, reflecting a higher prevalence of natural pertussis infection. The anti-PT titers gradually decreased among older age groups, although a peak occurred in the 11 to 15-year age group. The sequential changes in anti-FHA titers followed those of anti-Pt titers in the younger age groups, but the anti-FHA titers were persistently elevated beyond 15 years of age. The antibody levels were similar in the two sexes, except that anti-PT titers were higher in males of 19 to 20 months and 21 to 30 years of age. Anti-PT titers were equivalent between neonates (0-2 months) and pregnant women, but anti-FHA titers were much lower in neonates. CONCLUSIONS: The seroprevalence patterns in this study indicate that young children, adolescents, and even adults remain at risk of pertussis, despite the current immunization program. Booster vaccinations after completion of the current four-dose immunization schedule, possibly continuing into adolescence, should be considered to block the transmission of infection.

Adhesins, Bacterial↗
PubMed2000

Bacteremia due to Campylobacter species: high rate of resistance to macrolide and quinolone antibiotics.

BACKGROUND AND PURPOSE: Although the rate of isolation of Campylobacter from stool specimens in Taiwan is similar to those in other developed countries, Campylobacter bacteremia has rarely been reported in Taiwan, and the patterns of antimicrobial susceptibility of blood isolates to various antimicrobial agents remain unknown in the Taiwanese population. The purpose of this study was to determine the clinical characteristics of patients with Campylobacter infection in a university hospital in Taiwan and the antimicrobial susceptibility patterns of the Campylobacter isolates. METHODS: We retrospectively reviewed medical records of all patients with Campylobacter bacteremia treated in a university hospital between January 1991 and March 1999. Minimum inhibitory concentrations of 13 antimicrobial agents to 10 stored blood isolates were determined using the E-test. RESULTS: Approximately half (52%) of the 21 patients had chronic liver disease and one-quarter had hepatobiliary or gastrointestinal malignancies. Thirteen (62%) patients had conditions that were associated with gastroenteritis. Other clinical manifestations associated with Campylobacter infection included cellulitis, perinatal sepsis, peritonitis, vascular catheter-related infection, and primary bacteremia. The duration of illness was generally short: approximately half (52%) of the 21 patients had fever lasting for only 1 day. Antimicrobial susceptibility testing of the 10 isolates revealed that most of the blood isolates were resistant to erythromycin and nalidixic acid (100% and 90%, respectively), while the rate of cross-resistance between erythromycin and azithromycin was 70%, and that between nalidixic acid and ciprofloxacin was 67%. CONCLUSIONS: Our observations suggest that Campylobacter bacteremia should be included in the differential diagnosis of patients with chronic liver disease or malignancies involving the hepatobiliary system or gastrointestinal tract who present with fever and gastroenteritis. Clinicians in Taiwan should be alert to the high rate of resistance of Campylobacter isolates to macrolide and quinolone antibiotics.

Adolescent↗
PubMed2000

Immunogenicity and safety of an inactivated hepatitis A vaccine in Taiwanese adults and children.

The safety and immunogenicity of an inactivated hepatitis A vaccine (AVAXIM, 160 antigen units) was evaluated in 190 subjects: 50 children aged from 2 to 5 years, 70 children aged from 6 to 17 years and 70 adults aged from 18 to 30 years in a monocentric, open, non-controlled, phase III trial conducted in Taipei, Taiwan from December 1996 to October 1997. The vaccine was administered intramuscularly, with a two-dose schedule 6 months apart. Clinical adverse events were monitored during the seven days following each injection. Hepatitis A virus (HAV) antibody titers were measured by modified radioimmunoassay on the day of inclusion and four weeks after both the first dose and booster injection. Among the 190 subjects who received the first dose, 174 (91.6%) were initially HAV seronegative and 16 (8.4%) were HAV seropositive at inclusion. One hundred and seventy-four subjects (91.6%) received the booster dose and completed the study. One month after the first dose, all the subjects, whatever the age, presented HAV antibody titers over 20 mIU/ml. In children (2 to 17 years), the GMT was 136 mIU/ml at week 4 and 7,906 mIU/ml four weeks after the booster dose. In adults (> or = 18 years), GMT values were 93 mIU/ml at week 4 and 3,655 mIU/ml four weeks after the booster. These results show a strong anamnestic response to the second dose of vaccine and are compatible with long-term antibody persistence in each age group. The vaccine was safe and well tolerated. No vaccine-related serious adverse event occurred. No immediate reaction occurred. The majority of the reactions were reported by adults after the primary injection. Local reactions (pain and redness) were reported by 9.0% and 4.0% of the subjects after the primary and the booster doses, respectively. Systemic reactions (mainly myalgia/arthralgia or asthenia) affected less than 10% of the subjects after the first dose and less than 3% after the booster. Results from this study in a Taiwanese population are consistent with those obtained with the same vaccine in previous European studies in children and adults, and suggest that AVAXIM (160 AU) is suitable for use in all subjects aged over 2 years.

Adolescent↗