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Biomedical subjects

H S Lee

Publications and source records attributed to H S Lee.

At least 19 recordsLinked to original sources
PubMed1992

Mutation of p53 gene in hepatocellular carcinoma in Taiwan.

To elucidate the role of p53 mutation in hepatocarcinogenesis in Taiwan, a hepatitis B viral infection hyperendemic area, exons 5 to 8 of the p53 gene in the tumor tissue of 61 hepatocellular carcinomas were amplified and sequenced. A total of 20 cases (32.8%) were found to have mutations; 36.6% (15 of 41) for the hepatitis B surface antigen positive group and 25.0% (5 of 20) for the hepatitis B surface antigen negative group. The corresponding normal liver showed no mutation. The mutation is widely distributed throughout exons 5 to 8. Only 4 cases (6.6%), all positive for hepatitis B surface antigen, had a specific hot spot mutation at codon 249 with G to T transversion. Our results show that scattered point mutations in p53 are not uncommon in hepatocellular carcinoma samples from Taiwan and may be important in the development of this cancer. However, the aflatoxin related specific mutation seems much less related to the genesis of hepatocellular carcinoma in Taiwan.

Adult↗
PubMed1992

Calcitonin gene-related peptide in nucleus ambiguus motoneurons in rat: viscerotopic organization.

Calcitonin gene-related peptide has been reported in the rat nucleus ambiguus. This nucleus comprises a dorsal division that is the source of special visceral efferents innervating the striated muscle of the upper alimentary tract and a ventral division supplying general visceral efferents primarily to the heart. The distribution of calcitonin gene-related peptide immunoreactive neurons in the two divisions was determined by using a combination of immunocytochemical techniques and fluorescent retrograde tracing. In 22 rats, injections of Fluoro-Gold were made into either the supranodosal vagus nerve, palatopharynx, larynx, esophagus, or heart. Following colchicine injection, medullary sections were processed immunocytochemically for calcitonin gene-related peptide. Injection of Fluoro-Gold into the supranodosal vagus resulted in prominent labeling of neurons in the dorsal and ventral divisions of the nucleus ambiguus. The majority of fluorescent labeled neurons in the dorsal division were found to be immunoreactive for calcitonin gene-related peptide, while those labeled neurons in the ventral division were unreactive for the peptide. With esophageal, and palatopharyngeal and cricothyroid injections, many fluorescent labeled neurons that were immunoreactive for calcitonin gene-related peptide were found respectively in the compact and semicompact formations of the dorsal division. In contrast, injections of the heart resulted in fluorescent labeled neurons, which were unreactive for calcitonin gene-related peptide, localized to the external formation. The results demonstrate that calcitonin gene-related peptide immunoreactive neurons are localized entirely to the dorsal division of the nucleus ambiguus and that all striated muscular areas of the alimentary tract are innervated by calcitonin gene-related peptide containing motoneurons. The localization of calcitonin gene-related peptide to vagal motoneurons also known to contain acetylcholine and the increase in acetylcholine receptor synthesis caused by this peptide suggest that calcitonin gene-related peptide acts as a cotransmitter with acetylcholine in special visceral efferent vagal motoneurons.

Animals↗
PubMed1992

Alloantigenicity of human endothelial cells. 1. Frequency and phenotype of human T helper lymphocytes that can react to allogeneic endothelial cells.

To determine the relative ability of allogeneic endothelial cells to stimulate helper T lymphocytes (HTL), human PBMC or purified T cells were incubated in conventional lymphocyte microcultures or in limiting dilution microcultures with allogeneic human umbilical vein endothelia (HUVE), with cytokine-treated allogeneic HUVE, or with allogeneic peripheral blood monocytes. These cultures were tested for IL-2 production as an index of HTL stimulation. Dose-response studies in conventional lymphocyte cultures indicated that allogeneic monocytes were better than allogeneic HUVE at stimulating IL-2 production. Limiting dilution analyses revealed that untreated HUVE and TNF-treated HUVE stimulated small numbers of HTL (approximately 1 HTL/30,000 PBMC), whereas 5 to 10 times more HTL were stimulated by IFN-gamma-treated HUVE and 10 to 20 times more HTL were stimulated by allogeneic monocytes. Serologic deletion studies revealed that most of the high frequency HTL responding to IFN-gamma-treated HUVE were CD4+, whereas most of the low frequency HTL responding to nontreated HUVE or to TNF-treated HUVE were CD8+. Interestingly, mAb to MHC class I and class II molecules, which significantly impaired HUVE-induced proliferation, caused little interference with HUVE-induced IL-2 production. Finally, polymerase chain reaction analysis demonstrated that untreated allogeneic HUVE cells could stimulate PBMC to produce mRNA for IFN-gamma, as well as for IL-2. These data demonstrate the following hierarchy of allogeneic stimulatory capacity for human HTL: monocytes greater than IFN-gamma-treated HUVE much greater than TNF-treated HUVE = nontreated HUVE. Further, these data suggest that non-activated allogeneic endothelial cells can initiate immune responses by inducing IL-2 and IFN-gamma. Because IFN-gamma can induce MHC class II expression by the endothelial cells, this could recruit large numbers of CD4+ T cells for IL-2 production.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1992

Effect of the serotonin agonist, MK-212, on body temperature in schizophrenia.

The effects of 6-chloro-2-(1-piperaziny)pyrazine (MK-212), a centrally acting 5-HT1C/5-HT2 agonist, on body temperature and behavior were assessed using a single-blind cross-over design in 23 schizophrenic patients and 22 normal controls. Body temperature was assessed before drug administration and at 30-min intervals for 3 hr. Each subject was administered placebo or MK-212. MK-212 significantly elevated temperature in normal controls. There was no overall MK-212-induced increase in temperature compared to placebo in the schizophrenic patients; however, 13 of 23 (56.5%) patients had a larger increase in temperature after MK-212 than placebo, 3 of 23 (13.1%) had no change, whereas the temperature change after placebo was greater than after MK-212 in 7 of 23 (30.4%) patients. MK-212 produced significant increases in nausea, feeling strange, and arousal but these effects did not differ between groups. These results are consistent with decreased 5-HT2 receptor responsivity in some patients with schizophrenia.

Adult↗
PubMed1992

High-performance liquid chromatographic determination of rifapentine in serum using column switching.

A high-performance liquid chromatographic method with column switching has been developed for the determination of rifapentine in serum. The serum samples were injected onto a precolumn packed with Corasil RP C18 (37-50 microns) after simple dilution with an internal standard in a 1% ascorbic acid solution. Polar serum components were washed out using 0.05 M phosphate buffer. After valve switching, the concentrated drugs were eluted in the back-flush mode and separated by a mu Bondapak C18 column with acetonitrile-tetrahydrofuran-0.05 M phosphate buffer (pH 7.0) (42:5:53, v/v/v) as the mobile phase. The method showed excellent precision with good sensitivity and speed, and a detection limit of 0.1 microgram/ml. The total analysis time was less than 25 min and the mean coefficients of variation for intra- and inter-assay were less than 4.8%. The method has been successfully applied to serum samples from dogs after the oral administration of rifapentine.

Animals↗
PubMed1992

RNase X2, a pistil-specific ribonuclease from Petunia inflata, shares sequence similarity with solanaceous S proteins.

Petunia inflata, a species with gametophytic self-incompatibility, has previously been found to contain a large number of ribonucleases in the pistil. The best characterized of the pistil ribonucleases are the products of the S alleles, the S proteins, which are thought to be involved in self-incompatibility interactions. Here we report the characterization of a gene encoding another pistil ribonuclease of P. inflata, RNase X2. Degenerate oligonucleotides, synthesized based on the amino-terminal sequence of RNase X2, were used as probes to isolate cDNA clones, one of which was in turn used as a probe to isolate genomic clones containing the gene for RNase X2, rnx2. The deduced amino acid sequence of RNase X2 shows 42% to 71% identity to the 20 solanaceous S proteins reported so far, with the highest degree of similarity being to S3 and S6 proteins of Nicotiana alata. The cDNA sequence predicts a leader peptide of 22 amino acids, suggesting that RNase X2, like S proteins, is an extracellular ribonuclease. Also, similar to the S gene, rnx2 is expressed only in the pistil, and contains a single intron comparable in size and identical in location to that of the S gene. However, rnx2 is not linked to the S locus, and, in contrast to the highly polymorphic S gene, it is monomorphic. The possible biological function of RNase X2 is discussed.

Amino Acid Sequence↗
PubMed1992

Paracetamol elimination in Chinese and Indians in Singapore.

The 24 h urinary excretion of paracetamol and its conjugates after oral administration of about 15 mg/kg was studied in 24 Chinese and 24 Indian healthy young adult male volunteers living in Singapore. The Indians excreted a significantly lower fraction of sulphate conjugate (28.9% compared to 35.9% in the Chinese), and a correspondingly higher fraction as glucuronide conjugate (62.2% compared to 54.5% in the Chinese). There was no difference between the ethnic groups in terms of the urinary recovery of unchanged paracetamol (Indians 3.4%, Chinese 3.6%), glutathione-derived cysteine (Indians 2.3% and Chinese 2.2%) and mercapturic acid (Indians 3.6%, Chinese 3.8%) conjugates. The total fraction of administered paracetamol recovered in the urine was 84.7% and 85.7% in the Indian and the Chinese groups, respectively. Although the total glutathione derived conjugates recovered in the two ethnic groups were similar (Indians 5.9%, Chinese 6%), the values were lower than those reported previously for Caucasians in Scotland (9.3%).

Acetaminophen↗
PubMed1992

Urinary response to in vivo lipid peroxidation induced by vitamin E deficiency.

Experiments were carried out to measure the urinary excretion of free and conjugated malonaldehyde (MDA) and other thiobarbituric acid reactive substances (TBARS) in vitamin E deficient and vitamin E supplemented rats. From both dietary groups, six TBA positive fractions were isolated, in addition to that containing free MDA, by high-performance liquid chromatography (HPLC) on a TSK-GEL G-1000PW column. Three of the fractions isolated were found to be significantly increased in vitamin E deficiency. After acid hydrolysis, only one of the above compounds produced free MDA which indicated the presence of derivatized MDA. Only this fraction exhibited fluorescence at excitation 370 nm and emission 450 nm. The five other fractions formed 2,4-dinitrophenylhydrazones (2,4-DNPH), indicating the presence of carbonyl groups, but the derivatized MDA fraction did not. No significant differences were found in free MDA levels between the vitamin E deficient and the vitamin E supplemented groups.

Animals↗
PubMed1992

A new acylated N-glycosyl lactam from Aristolochia contorta.

A new acylated glycoside isolated from the roots of Aristolochia contorta (Aristolochiaceae), has been characterized as aristolactam N-(6'-trans-p-coumaroyl)-beta-D-glucopyranoside [2]. Aristolactam-N-beta-D-glucopyanoside [1] was also isolated from the same source. Compound 2 showed relatively significant antibacterial activity against Gram-positive bacteria, based on disc diffusion and dilution methods.

Anti-Bacterial Agents↗
PubMed1992

Isolation of a yeast gene encoding a protein homologous to the human Tat-binding protein TBP-1.

We have cloned a putative yeast homolog of the gene encoding the human Tat-binding protein, TBP-1. The gene termed TBPY encodes a 45,243-dalton protein displaying a heptad repeat of hydrophobic amino acids reminiscent of a leucine zipper. Secondary structure predictions suggest the possibility of formation of an amphipathic helix that could further be organized into a coiled-coil. Additionally, the protein product of TBPY shows amino acid signatures characteristic of a large family of RNA and DNA helicases. We propose that the hydrophobic region of yTBP-1 participates in self-dimerization or heterodimerization.

ATPases Associated with Diverse Cellular Activitie↗
PubMed1992

Indicators of active and passive coping in myocardial infarction victims.

This retrospective study attempted to explore life events, personality factors, subjective perceptions, and coping reactions in myocardial infarction (MI) patients. Seventy-seven MI survivors participated in the study. The PERI Life Events Scale, the 16 PF personality inventory, and a questionnaire covering self-ratings of subjective perception and coping reactions were used to assess event-related influences. The following results were obtained: Multiple regression analyses yielded strong relationships between insecurity predicting perceived changeability, challenge, and threat. The number of prior events was a good predictor for problem solving and self-reflection, while self-attribution for the occurrence of the MI predicted self-blame and denial. A structural equation model indicated that anxiety and experience with stressful events were salient predictors for appraisal, whereas experience with prior events best predicted active coping, and socioeconomic status negatively predicted passive coping.

Adaptation, Psychological↗
PubMed1992

A study of silica nephrotoxicity in exposed silicotic and non-silicotic workers.

The possible human nephrotoxicity of silica has often been suggested by previous anecdotal reports and uncontrolled clinical studies of silicotic patients. Urinary excretions of albumin, alpha-1-microglobulin (AMG), and beta-N-acetyl-glucosaminidase (NAG) were measured in 33 male workers exposed to silica (mean duration of employment 16 years) and 19 male age matched non-exposed subjects with no history of primary or secondary renal diseases. Significantly higher urinary excretions of albumin and AMG were found in the workers exposed to silica. Silicotic subjects (n = 7) also had significantly high excretions of albumin, AMG, and NAG. All but one of the silicotic patients had ceased exposure from three to 17 years before the study. Our findings suggest that prolonged exposure to silica is associated with chronic irreversible nephrotoxicity in exposed workers.

Acetylglucosaminidase↗
PubMed1992

Diurnal variation in peak expiratory flow rate among workers exposed to toluene diisocyanate in the polyurethane foam manufacturing industry.

The diurnal variation in peak expiratory flow rate (PEFR) was studied in 26 mixers from eight factories making polyurethane foam, who were exposed to toluene diisocyanate (TDI), and 26 unexposed controls matched for age, race, and smoking. They were all men. The mean diurnal variation in PEFR of the mixers was 6.2%, which was significantly higher than the 4.3% for controls. Six mixers had a diurnal variation of greater than 15% on at least one day compared with none among the controls. There was, however, no overt cause of occupational asthma. All but one of the 24 environmental samples taken exceeded the short term exposure limit of 0.02 ppm for TDI. This accounted for the high prevalence (50%) of irritative symptoms such as cough and eye irritation. Forced expiratory volume in one second (FEV1) and FEV1/forced vital capacity (FVC) (%) was negatively correlated with duration of exposure to TDI. Foam workers may still have high exposure to TDI, high prevalence of irritative symptoms, increased diurnal variation in PEFR and evidence of chronic airway obstruction, particularly in those with greater than or equal to 10 years of exposure.

Adult↗
PubMed1992

Therapeutic effect of transcatheter oily chemoembolization therapy for encapsulated nodular hepatocellular carcinoma: CT and pathologic findings.

An emulsion of iodized oil and doxorubicin hydrochloride was intraarterially injected in 27 patients with encapsulated single nodular hepatocellular carcinoma (HCC). Computed tomography (CT) was performed 1-3 weeks after injection, and the lesions were resected 1-4 weeks thereafter. The percentages of tumor necrosis were evaluated in cut surfaces of resected specimens and were compared with the findings at iodized-oil CT. Six tumors with complete intratumor retention of iodized oil had 98% necrosis, and 21 tumors with incomplete retention had 64% necrosis. Two tumors with complete retention of iodized oil in the surrounding liver had 100% necrosis, while 16 tumors with partial retention and nine tumors without retention of iodized oil in surrounding liver had 74% and 62% necrosis, respectively. Complete retention of iodized oil in the tumor and surrounding liver demonstrated the best therapeutic effects. Evaluation of the pattern and distribution of iodized oil in the tumor and surrounding liver with iodized-oil CT is useful in the assessment of the therapeutic effects of transcatheter arterial embolization in encapsulated nodular HCCs.

Carcinoma, Hepatocellular↗
PubMed1992

Personality, life events and coping in the oldest-old.

This paper compares older adults in their sixties, eighties, and 100s on personality, experience of life events, and coping. A secondary goal was to test a structural model of adaptation. Participants (165) filled out a personality inventory, life-event lists, and coping and mental health measures. Results revealed differences in personality: centenarians scored higher on dominance, suspiciousness, and imagination. While centenarians scored lower on active behavioral coping than other age groups, they used cognitive strategies when coping with health and family events. Results from the structural equation model indicated that extraversion and anxiety predicted morale and mental health.

Adaptation, Psychological↗