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Biomedical subjects

C N Lee

Publications and source records attributed to C N Lee.

At least 37 records · Page 2Linked to original sources
PubMed2001

Inhibitory effect of stevioside on calcium influx to produce antihypertension.

Stevioside is a sweet-tasting glycoside occurring abundantly in the leaves of Stevia rebaudiana (Compositae). It has been used popularly in Japan and Brazil as a sugar substitute for decades. Previous study has shown that it lowered blood pressure in spontaneously hypertensive rats (SHRs) when administered intravenously. This study shows that intraperitoneal injection of stevioside 25 mg/kg also has antihypertensive effect in SHRs. In isolated aortic rings from normal rats, stevioside could dose-dependently relax the vasopressin-induced vasoconstriction in both the presence and absence of endothelium. However, stevioside had no effect on phenylephrine- and KCl-induced phasic vasoconstriction. In addition, stevioside lost its influence on vasopressin-induced vasoconstriction in Ca(2+)-free medium. The results indicate that stevioside caused vasorelaxation via an inhibition of Ca(2+) influx into the blood vessel. This phenomenon was further confirmed in cultured aortic smooth muscle cells (A7r5). Using 10(-5) M methylene blue for 15 min, stevioside could still relax 10(-8) M vasopressin-induced vasoconstriction in isolated rat aortic rings, showing that this vasorelaxation effect was not related to nitric oxide. The present data show that the vasorelexation effect of stevioside was mediated mainly through Ca(2+) influx inhibition.

Animals↗
PubMed2001

Human papillomavirus infection in non-neoplastic uterine cervical disease in Hong Kong.

The polymerase chain reaction (PCR) was used to detect and identify human papillomavirus (HPV) in 108 cases of formalin-fixed, paraffin-embedded, non-neoplastic uterine cervical biopsy tissue retrieved from the surgical pathology archives of the Department of Pathology, Caritas Medical Centre, Hong Kong. After DNA extraction, HPV L1 gene primers were used to detect the presence of HPV, and type-specific primers (to HPV types 6, 11, 16, 18, 31 and 33) were used to identify the specific HPV type on HPV L1-positive cases. PCR amplification of the beta-globin gene was used to ensure the quality of amplifiable DNA extracted. Of 94 cases that yielded sufficient good-quality DNA for PCR analysis, three (one endocervical polyp, one chronic inflammation with erosion, and a normal biopsy) had detectable HPV infection. Two of these had high-risk HPV type 16; the other had an uncommon HPV type. In view of the low incidence of HPV found in these patients, large-scale population screening of clinical samples using PCR to detect the presence of HPV and identify high-risk asymptomatic patients would not be cost-effective.

Adult↗
PubMed2001

Amantadine-resistant influenza A virus in Taiwan.

BACKGROUND AND PURPOSE: Amantadine and rimantadine have been used for treatment and prophylaxis of influenza A virus infection. We examined the amantadine susceptibility of field isolates of influenza A virus in Taiwan from 1996 to 1998 to monitor the presence of resistant strains. METHODS: Eighty-four field isolates of influenza A virus were examined for resistance to amantadine by plaque inhibition assay. Virus isolates with amantadine 50% inhibitory concentrations (IC50) greater than 0.9 microgram were chosen for sequence analysis of the M gene that is the molecular target for amantadine/rimantadine. Reverse transcription-polymerase chain reaction (RT-PCR) was used to amplify the viral RNA. RT-PCR products were examined and purified by agarose gel electrophoresis for further sequence analysis. The Genetics Computer Group Sequence Analysis Package and the neighbor-joining method listed in the Molecular Evolutionary Genetic Analysis package were used for phylogenetic analysis. RESULTS: One field strain was amantadine resistant (IC50 > 10 micrograms/mL), with a mutation (position 31, serine to asparagine) in the M2 protein. The resistant virus was isolated from a non-immunocompromised child without a history of amantadine/rimantadine treatment. None of the family members reported previous exposure to amantadine/rimantadine. CONCLUSIONS: In this series, amantadine-resistant influenza A (H1N1) virus was isolated from a non-immunocompromised Taiwanese child without a known history of exposure to this drug. Resistant field isolates were rare. Due to the increasing use of amantadine/rimantadine in Taiwan, continued surveillance for amantadine/rimantadine-resistant influenza A viruses is warranted.

Amantadine↗
PubMed2000

Enhanced antitumor immunity by fusion of CTLA-4 to a self tumor antigen.

The idiotypic determinant (Id) of the immunoglobulin expressed by a B-cell malignancy can serve as an effective tumor-specific antigen but is only weakly immunogenic. This study demonstrates that the immunogenicity of the tumor Id protein can be dramatically increased by directing it to antigen-presenting cells (APCs). Cytotoxic T-lymphocyte antigen 4 (CTLA-4) present on activated T cells has a strong binding affinity to both B7-1 and B7-2 molecules, which are primarily expressed on APCs. After construction of a fusion protein consisting of Id and CTLA-4 (Id-CTLA4), mice immunized with the fusion protein induced high titers of Id-specific antibody and T-cell proliferative responses without adjuvants and were protected from lethal tumor challenge. The Id-CTLA4 fusion protein was so potent that even low doses (down to 0.1 microg) of the immunogen were able to elicit strong antibody responses. By using an Id-CTLA4 mutant protein, the ability to bind B7 molecules on APCs was shown to be required for the enhanced immunogenicity of Id-CTLA4. These findings demonstrate that fusing CTLA-4 to a potential tumor antigen represents an effective approach to prime antitumor immunities in vivo and may be applicable to the design of vaccines for a variety of other diseases. (Blood. 2000;96:3663-3670)

Abatacept↗
PubMed2000

Interaction between HIV type 1 glycoprotein 120 and CXCR4 coreceptor involves a highly conserved arginine residue in hypervariable region 3.

Several seven-transmembrane chemokine receptors are known to function as entry coreceptors for human immunodeficiency virus type 1. CCR5 and CXCR4 are the major coreceptors for non-syncytium-inducing (NSI) and syncytium-inducing (SI) viruses, respectively. During the natural course of infection, the emergence of variants with a phenotypic transition from NSI to SI and rapid disease progression is associated with expanded coreceptor usage to CXCR4. Characteristic amino acids at several positions in the hypervariable region 3 (V3) of gp120 have been linked to CXCR4 utilization. Previously, we reported that a highly conserved arginine residue of V3 played an important role in CCR5 utilization. In this study, the possible involvement of the same arginine residue in CXCR4 utilization was investigated. Amino acid substitutions introduced to this arginine on R5X4 viruses were found to have a significant effect on their utilization of CXCR4. These results, taken together with those reported previously, suggest that this highly conserved arginine may contribute to the functional convergence of chemokine coreceptor utilization by human immunodeficiency viruses and may represent a unique target for future antiviral design.

Amino Acid Sequence↗
PubMed2000

Hemostatic suturing technique for uterine bleeding during cesarean delivery.

BACKGROUND: If medical management is unsuccessful in controlling postpartum hemorrhage, conservative surgical intervention or cesarean hysterectomy is required. TECHNIQUE: Hemostatic multiple square suturing using a straight number 7 or number 8 needle and number 1 chromic catgut is a new surgical technique to approximate anterior and posterior uterine walls, especially in areas where there is heavy bleeding. It controls postpartum hemorrhage by attachment and compression of the hemorrhage site of the endometrium or myometrium. EXPERIENCE: We used this technique in 23 women with postpartum hemorrhages at cesarean who did not respond to conservative treatment. In all 23 cases, bleeding decreased markedly and hysterectomy was avoided. All resumed normal menstrual flow after surgery. In four cases, further pregnancy was achieved after this method was used. CONCLUSION: Hemostatic multiple square suturing is an easy, safe, conservative surgical alternative to hysterectomy for treating uncontrollable postpartum hemorrhage.

Cesarean Section↗
PubMed2000

Angiogenesis of endometrial carcinomas assessed by measurement of intratumoral blood flow, microvessel density, and vascular endothelial growth factor levels.

OBJECTIVE: To evaluate the relationship between blood flow in the tumor assessed by color Doppler ultrasound, microvessel density, and vascular endothelial growth factor levels in endometrial carcinoma. METHODS: Forty-nine patients undergoing surgery for endometrial carcinoma were enrolled. Transvaginal color Doppler ultrasound was performed preoperatively and the lowest resistance index (RI) in the tumor was recorded for analysis. Vascular endothelial growth factor in the tumor was quantified by enzyme immunoassay. The microvessel density of the excised tumor was assessed immunohistochemically. The relationships between the corresponding RI, microvessel density, and vascular endothelial growth factor level of the tumor tissues and clinical and pathologic parameters were analyzed. RESULTS: Significantly lower RIs were noted in tumors of stage II or greater (0.37 compared with 0.50, P <.001), of high histologic grade (grade 3) (0.34 compared with 0.49, P =.004), with deep myometrial invasion (one-half depth or greater) (0.39 compared with 0.49, P =.002), with lymphovascular emboli (0.38 compared with 0.49, P <.001), or with lymph node metastasis (0.30 compared with 0.49, P <.001) compared with stage I tumors and tumors of histologic grade 1 or 2, with superficial myometrial invasion, without lymphovascular emboli, or with no lymph node metastasis. Increased vascular endothelial growth factor levels and microvessel density (x200 field) also were detected in tumors of stage II or greater (975 compared with 129 pg/mg, P =.014; and 88 compared with 61, P =.018, respectively), with lymphovascular emboli (1138 compared with 120 pg/mg, P =.002; and 86 compared with 63, P =.023), or with lymph node metastasis (1011 compared with 95 pg/mg, P <.001; and 98 compared with 61, P =. 019). Resistance index, microvessel density, and vascular endothelial growth factor levels in the tumor showed linear correlations (RI compared with microvessel density: r = -.32, P =. 03; RI compared with vascular endothelial growth factor levels: r = -.40, P =.004; microvessel density compared with vascular endothelial growth factor levels: r =.36, P =.011). CONCLUSION: Blood flow assessed by color Doppler ultrasound has histologic and biologic correlations with angiogenesis and vascular endothelial growth factor levels and might play an important role in predicting tumor progression and metastasis in endometrial carcinoma.

Adult↗
PubMed2000

Vascular endothelial growth factor and prognosis of cervical carcinoma.

OBJECTIVE: To evaluate vascular endothelial growth factor (VEGF) as a marker for predicting lymph node metastasis and an independent prognostic factor of early-stage cervical carcinoma. METHODS: One hundred thirty-five women with stage IB-IIA cervical carcinoma had radical abdominal hysterectomies and pelvic lymph node dissections. Intratumoral cytosol VEGF concentrations were assayed with enzyme immunoassay. Histopathologic items and cytosol VEGF-influencing clinical outcomes were compared. RESULTS: Twenty-two women (16.3%) who had disease recurrence had higher levels of cytosol VEGF (1020 versus 112 pg/mg protein, P <.001) than those without recurrence. Using a cutoff value of 400 pg/mg protein resulted in best sensitivity of 75%, best specificity of 70%, positive predictive value of 41%, and negative predictive value of 92%. Only overexpressed cytosol VEGF (hazard ratio 6.44, P <.001) was an independent prognostic factor of disease-free survival. The overexpressed cytosol VEGF (hazard ratio 4.50, P =.021) and positive lymphovascular emboli (hazard ratio 4.11, P =.045) were independent prognostic factor of overall survival. CONCLUSION: Cytosol VEGF might be a biomarker for the status of pelvic lymph nodes in early-stage cervical carcinoma and an independent prognostic indicator of its outcome.

Adult↗
PubMed2000

Prenatal depiction of angioarchitecture of an aneurysm of the vein of Galen with three-dimensional color power angiography.

A fetus with a large supratentorial cyst and cardiomegaly was encountered at 33 weeks of gestation. The cyst appeared as an aneurysmal, fluid-filled structure extending posteriorly with a finger-like appendage. Using color flow mapping, we disclosed rapid in-and-out blood flow with marked turbulence within the cyst. For evaluation of its blood supply and venous drainage of the vascular malformation, a three-dimensional reconstruction of the power Doppler image was conducted. The results revealed that the vascular malformation was supplied by a small contralateral aneurysm from the branches of Willis' circle, draining posteriorly into an abnormal falcine sinus and then into the superior sagittal sinus. No other fetal abnormality such as hydrocephalus or hydrops was discovered. The prenatal diagnosis of an aneurysm of the vein of Galen was made on the basis of the gray-scale, color Doppler findings, and also the angioarchitecture obtained by three-dimensional power Doppler imaging. The woman was admitted at 37 weeks of gestation due to labor onset and delivered the baby via the vaginal route without complication. Postnatal angiography and magnetic resonance imaging confirmed the diagnosis of an aneurysm of the vein of Galen, and the angioarchitecture depicted it before birth. We suggest that three-dimensional power Doppler ultrasonography may assist in the diagnosis of an aneurysm of the vein of Galen, and precisely delineate the complicated corresponding vasculature. This may guide postnatal management and predict the prognosis more accurately.

Adult↗
PubMed2000

Antenatal diagnosis of congenital hepatoblastoma in utero.

A fetus with a huge hepatic tumor was detected by sonography at 36 weeks of gestation. The mass appeared as a single, solid and polylobular tumor located in the right lobe of the liver. Foci of hemorrhage, necrosis and some tiny calcifications were seen. The adjacent right kidney appeared normal but was displaced. The right adrenal gland was not visualized. Three-dimensional power Doppler sonography further depicted the corresponding vascular anatomy of the tumor, including its vascularization pattern and blood supply. The tumor was situated to the right of the umbilical vein and portal sinus, possibly deriving its blood supply from the portal circulation. The fundamental findings suggested the diagnosis of hepatoblastoma by exclusion of other possibilities. The baby was delivered by Cesarean section at 36 weeks' gestation, due to signs of fetal distress. Unfortunately, hypotension, tachycardia, and tachypnea developed shortly after birth. Surgical intervention was performed, but intractable bleeding occurred intra-operatively. The infant died at 6 days of age. Autopsy confirmed the diagnosis of hepatoblastoma. We believe this is the first reported case of the antenatal diagnosis of congenital hepatoblastoma.

Adult↗
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

Determination of human immunodeficiency virus type 1 subtypes in Taiwan by vpu gene analysis.

The genetic diversity of human immunodeficiency virus (HIV) type 1 (HIV-1) has been characterized mainly by analysis of the env and gag genes. Information on the vpu genes in the HIV sequence database is very limited. In the present study, the nucleotide sequences of the vpu genes were analyzed, and the genetic subtypes determined by analysis of the vpu gene were compared with those previously determined by analysis of the gag and env genes. The vpu genes were amplified by nested PCR of proviral DNA extracted from 363 HIV-1-infected individuals and were sequenced directly by use of the PCR products. HIV-1 subtypes were determined by sequence alignment and phylogenetic analysis with reference strains. The strains in all except one of the samples analyzed could be classified as subtype A, B, C, E, or G. The vpu subtype of one strain could not be determined. Of the strains analyzed, genetic subtypes of 247 (68.0%) were also determined by analysis of the env or gag gene. The genetic subtypes determined by vpu gene analysis were, in general, consistent with those determined by gag and/or env gene analysis except for those for two AG recombinant strains. All the strains that clustered with a Thailand subtype E strain in the vpu phylogenetic analyses were subtype E by env gene analysis and subtype A by gag gene analysis. In summary, our genetic typing revealed that subtype B strains, which constituted 73.8% of all strains analyzed, were most prevalent in Taiwan. While subtype E strains constituted about one-quarter of the viruses, they were prevalent at a higher proportion in the group infected by heterosexual transmission. Genetic analysis of vpu may provide an alternate method for determination of HIV-1 subtypes for most of the strains, excluding those in which intersubtype recombination has occurred.

Amino Acid Sequence↗
PubMed2000

Quantitative competitive reverse transcription-PCR for quantification of dengue virus RNA.

A quantitative competitive reverse transcription-PCR assay was developed to quantify dengue virus RNA in this study. The main features include a primer pair targeting a highly conserved region in the capsid and the addition of competing RNA that contains an internal deletion to provide a stringent internal control for quantification. It can be utilized to quantify RNA isolated from the four dengue virus serotypes but not RNA isolated from other flaviviruses, including Japanese encephalitis virus and hepatitis C virus, both prevalent in Asia. It can also be used to quantify dengue virus RNA isolated from the plasma of infected individuals. The sensitivity of the assay was estimated to be 10 to 50 copies of RNA per reaction, and twofold differences in virus titer are distinguishable. This assay is a convenient, sensitive, and accurate method for quantification and can be used to further understanding of the pathogenesis of dengue virus infection.

Culture Media↗
PubMed2000

Effects of epidural fentanyl on labor pain during the early period of the first stage of induced labor in nulliparous women.

BACKGROUND AND PURPOSE: It is generally accepted that epidural injection with local anesthetics and narcotics administered when the cervix has dilated to a diameter exceeding 4 cm can adequately control labor pain. However, many nulliparous women still suffer from labor pain for a few hours prior to the administration of epidural analgesia. This study examined the effectiveness of relief of labor pain obtained by injection of narcotics epidurally once the labor pain begins and the subject requests analgesia. METHODS: Subjects scheduled for induced labour were divided into three groups: Group A (n = 60) received 5 x 10(-4)% fentanyl (10-20 mL) administered epidurally to relieve early first-stage labor pain. Group B (n = 60) received no analgesic in the early first stage of labor. For groups A and B, when cervical dilatation exceeded 4 cm, 10 to 15 mL of 5 x 10(-2)% bupivacaine and 2 x 10(-4)% fentanyl were injected epidurally and a continuous low dosage was maintained until full dilatation of the cervix resulted. Group C (n = 198) received no analgesic during the entire labor course. RESULTS: There were no significant differences in the duration of the early period of the first stage of labor, the duration of the late period of the first stage, the duration of the second stage, the Apgar score, or the arterial blood gas of neonates among the three groups. However, group C had a significantly higher cesarean section rate (28.8%) than group A (16.7%) or group B (15%). Pain scores assessed with the Visual Analog Scale (VAS) throughout the entire labor course, were lower in group A than in group B; particularly during the early period of the first stage. The VAS scores in both groups A and B were significantly lower than those in group C during the late period of the first stage of labor. CONCLUSIONS: The results indicate that once labor pain begins and the subject requests analgesia, epidural injection with fentanyl alone can relieve labor pain during the early period of the first stage. The analgesia does not cause adverse effects to the mothers or neonates. In addition, the labor course and the method of delivery are not affected.

Adult↗
PubMed2000

Enteric adenovirus infection in children in Taipei.

Enteric adenoviruses (EAds), including type 40 (Ad40) and 41 (Ad41), can cause acute and severe diarrhea in young children. To delineate the epidemiological features of pediatric EAds infection in Taiwan, we conducted a retrospective study of all cases of EAds gastroenteritis in children treated at National Taiwan University Hospital for the period from July 1993 to December 1997. Stool samples were tested for the presence of Ad40 or Ad41 by enzyme immunoassay (EIA). A total of 64 cases of EAds infection in 63 children aged from 8 days to 81 months old with a median age of 9.5 months treated during the study period were identified. The male-to-female ratio was 1.63 (39/24). No obvious seasonal clustering of EAds cases was noted. Most patients (76.6%) were infected before the age of 2 years. Clinical features included diarrhea (96.9%), fever (54.7%), vomiting (45.3%), mild dehydration (43.8%), symptoms of upper respiratory tract infection (21.9%), and abdominal pain (12.5%). Analysis of fecal samples in patients with diarrhea showed watery diarrhea in 72.2%, diarrhea with mucus in 20%, diarrhea with blood in 3.1% and diarrhea with mucus and blood in 1.6 % of all patients. Nearly one-half (43.5%) of the patients had diarrhea for more than 7 days. Thirty-seven patients (57.8%) were hospitalized due to gastroenteritis or other unrelated diseases, and 11 patients (17.2%) acquired enteric adenovirus infection during hospitalization for other underlying disease. Twelve patients (18.8%) had mixed infections, which included rotavirus, respiratory syncytial virus (RSV) and Salmonella species. There were no deaths in this series. The findings of this study suggest that EAds are important etiologic microbes of pediatric gastroenteritis.

Adenoviridae Infections↗
PubMed2000

Rotavirus gastroenteritis in children: 5-year experience in a medical center.

Rotavirus infection is the leading cause of childhood gastroenteritis. We retrospectively reviewed cases of rotavirus gastroenteritis at National Taiwan University Hospital from January 1993 to December 1997. During the study period there were 429 patients with rotavirus infection with ages ranging from 1 day to 16 years with a median of 13 months. The male-to-female ratio was 1.2:1. Infection occurred before the age of 2 years old in 76% of patients. The seasonal peak occurred in the late winter and early spring during 1993 to 1996, but the case number increased in late spring and summer in 1997. The G serotype of the rotavirus was identified in 302 patients (70%). Vomiting and dehydration developed more frequently following infection with G1 rotaviruses, while an increased frequency of seizures was noted following G2 infection; the differences were not statistically significant. One patient had two episodes of infection; the first one was caused by G1 rotavirus, and the strain causing the second infection could not be typed. In conclusion, the results suggest that there is a strong seasonal variation in the incidence and characteristics of rotavirus infection in Taipei area. The infections caused by G1 and G2 rotaviruses were clinically indistinguishable.

Adolescent↗