Biomedical subjects

T H Lin

Publications and source records attributed to T H Lin.

At least 55 records · Page 3Linked to original sources

PubMed1998

Association between oxidative stress and cytokine production in nickel-treated rats.

The aim of this study was to evaluate a possible relationship between lipid peroxidation, cytokine production, such as interleukin-1 (IL-1), tumor necrosis factor alpha (TNF-alpha), and transforming growth factor beta (TGF-beta), and hepatotoxicity of rats after nickel chloride (NiCl2) acute poisoning. Administration of NiCl2 significantly elevated the levels of malondialdehyde (MDA), IL-1, TNF-alpha, and TGF-beta in the serum of rats. The dose-effect relationship for the increase of serum MDA, as observed in the present study, corresponds closely to the increase of IL-1, TNF-alpha, and TGF-beta in serum. Treatment with ascorbic acid (Vit C) significantly lowered the levels of lipid peroxidation, cytokine production, and the activities of alanine transaminase and aspartate transaminase in the serum of the rats given NiCl2. The hepatic toxicity was increased in a dose-dependent manner and corresponds to the increase of serum IL-1, TNF-alpha, and TGF-beta. There was an association between lipid peroxidation and the levels of cytokines in serum of rats after NiCl2 administration. Reactive oxygen species may serve as a mediator of lipid peroxidation and production of cytokines in NiCl2 injection.

Animals↗

PubMed1998

Nickel toxicity to human term placenta: in vitro study on lipid peroxidation.

It has been reported that nickel (Ni) crosses the human placenta and produces teratogenesis and embryotoxicity. In the present study, the effects of nickel on human term placentas were investigated. In time-course experiments, placental tissue was incubated for 3, 6, 12, or 24 h with 2.5 mM Ni. The viability as determined by glucose consumption rate did not show any significant change from 3 to 12 h, whereas the permeability, lipid peroxidation, and Ni concentration were significantly increased compared to the control. In concentration-response studies, placental explants were incubated with 0.5, 1.0, 2.5, or 5 mM Ni for 12 h. The viability did not change significantly, except for 5 mM Ni, but the permeability and lipid peroxidation increased markedly in a concentration-dependent manner. Treatment with ascorbic acid or Zn decreased placental lipid peroxidation and permeability induced by Ni, but had no effect on lowering the Ni tissue content. Data show that Ni is toxic as evidenced by lipid peroxidative damage to placental membrane, and this metabolic change may be responsible for decreased placental viability, altered permeability, and potential subsequent embryotoxicity.

Cell Membrane Permeability↗

PubMed1998

Arsenic species in drinking water, hair, fingernails, and urine of patients with blackfoot disease.

A large number of residents on the southwest coast of Taiwan suffer from an endemic peripheral vascular disease called blackfoot disease. Although the etiology has been investigated since 1958, the cause of blackfoot disease remains unknown. Certain substances contained in artesian well water have been implicated as causal factors, including arsenic as the predominant element. Data in this study demonstrated that in the well water collected from blackfoot disease regions of Taiwan there was a marked increase in total arsenic concentrations, with the predominant species being inorganic arsenical compounds. The concentrations of organic methyl arsenicals were present in minimal amounts. The excretion of total arsenic, inorganic arsenic, monomethylarsonic acid, and trimethylarsenic acid in the urine of patients afflicted with blackfoot disease was significantly higher than for control subjects. Further, in patients with blackfoot disease the concentrations of total arsenic and inorganic arsenic were markedly elevated in the hair and fingernails. Data suggest that blackfoot disease is associated with individuals ingesting well, water contaminated with arsenic primarily in the inorganic form and that hair, fingernails, or urine specimens serve as equally effective biomarkers of exposure. The fact that arsenic intoxication as manifested by blackfoot disease is still prevalent despite the stoppage of well-water consumption for two decades illustrates the persistent nature of arsenic action.

Aged↗

PubMed1998

Direct determination of selenium in human blood plasma and seminal plasma by graphite furnace atomic absorption spectrophotometry and clinical application.

Direct determination of selenium (Se) in body fluids by graphite furnace atomic absorption spectrophotometry (GFAAS) may suffer from problems like severe background, matrix effects, preatomization losses, and spectral interferences. In this study we evaluate critically the influence on the accuracy of the direct determination of Se in blood plasma and seminal plasma by GFAAS, and propose a simple, rapid, and accurate method, suitable for routine clinical analysis. The method for blood plasma is mainly based on studies by the use of matched matrix and a Pd-Ni modifier, but for seminal plasma only a Pd modifier is required. The method developed was also applied to study the Se distribution in plasma protein fractions of patients with hepatocellular carcinoma. The Se in plasma of patients was significantly lower than that of the controls. The distribution pattern of Se in blood plasma fractions of patients was also different from that of the controls.

Adult↗

PubMed1998

Lipid peroxidation in liver of mice administrated with nickel chloride: with special reference to trace elements and antioxidants.

The relationship between Ni-induced hepatic lipid peroxidation (LPO) and the concentrations of Ni and trace elements was investigated in male ICR mice. The protective effects of antioxidants were also examined. Hepatic LPO and the concentrations of Ni, Fe, Cu, and Zn in the liver were enhanced after an ip injection of nickel chloride (NiCl2). Dose-response studies were conducted on male mice with different groups being injected with 50, 85, and 170 micromol Ni/kg. LPO increased significantly in a dose-dependent manner. In time-course studies, mice were administrated NiCl2 (170 micromol Ni/kg) and killed at intervals of 6, 12, 24, and 48 h after injection. Both LPO and the accumulation of Ni, Fe, Cu, and Zn in the liver showed a significantly positive time-course relationship after NiCl2 injection. At 1 h and 24 h after a single ip injection of 170 micromol Ni/kg, the mice were given an ip injection of ascorbic acid (vit C), glutathione (GSH), and selenium (Se). Vit C and GSH significantly decreased both the level of hepatic LPO and the concentration of Ni in the liver, but did not decrease the accumulation of Fe, Cu, and Zn. However, LPO in the experimental group of mice was different significantly from that in the control group. In conclusion, the results suggest that Ni-induced hepatic LPO may result from increasing the amounts of Ni, Fe, and Cu, since these elements are involved in the generation of hydroxyl radical by inducing the Fenton reaction, thus instigating the Ni-mediated hepatic LPO. The protective effects of vit C and GSH in hepatic LPO result not only from removing the oxygen reactive species, but also from decreasing the Ni concentration.

Animals↗

PubMed1998

The impact of a brief problem-solving training intervention for relatives of recently diagnosed breast cancer patients.

Previous studies have found high levels of psychological distress in women who have a family history of breast cancer. We evaluated a brief Problem-Solving Training (PST) intervention designed to reduce distress among women with a first-degree relative recently diagnosed with this disease. Participants were randomly assigned to either the PST group (N = 144) or a General Health Counseling (GHC) control group (N = 197). At baseline, these groups did not differ on any sociodemographic, risk factor, or psychological distress variables. We evaluated the impact of PST, relative to GHC, at the three-month follow-up assessment using a 2 (treatment group) x 2 (time of assessment) mixed factor analysis of variance (ANOVA). Although there were significant decreases in both cancer-specific and general distress in both the PST and GHC groups, the magnitude of these decreases did not differ. However, when PST participants were divided into those who regularly practiced the PST techniques and those who did not, significant differences emerged. Participants who regularly practiced the PST techniques had significantly greater decreases in cancer-specific distress [Impact of Event Scale (IEs) intrusion and avoidance subscales] compared to infrequent practicers and GHC participants. Effects on general distress were not found. Additional studies are needed to identify ways to promote the practice of PST techniques and to evaluate other psychosocial interventions for female relatives of breast cancer patients.

Adaptation, Psychological↗

PubMed1998

Effects of vitamin A pretreatment on nickel-induced lipid peroxidation and concentration of essential metals in liver, kidney and lung of mice.

In the present study we report the effects of pretreatment with large doses of vitamin A (Vit A, retinol) on hepatic, renal and pulmonary lipid peroxidation, and Ni and essential metal (Fe, Cu, Zn and Ca) concentrations in mice acutely exposed to nickel. Vitamin A (250,000 IU/kg per day) was administered by oral gavage to ICR mice for 7 days. On the 8th day, NiCl2 (5 mg Ni/kg body wt.) was injected i.p. to Vit A- or vehicle-pretreated mice. Vitamin A pretreatment alone did not alter lipid peroxidation in liver, kidney and lung. Lipid peroxidation in liver, kidney and lung was increased after treatment with NiCl2 alone. The extent of lipid peroxidation levels in Vit A + Ni treated mice was enhanced in liver, but reduced in kidney and lung. The Ni concentration in these three organs was below the detection limit (0.09 microg/g) in control and Vit A-pretreated mice. The accumulation of Ni in Vit A + Ni treated mice was increased in liver, but decreased in kidney and lung compared to Ni-treated mice. The concentrations of Fe, Cu, Zn and Ca in these organs were significantly increased in Ni-treated mice. In Vit A + Ni treated mice, compared to Ni-treated mice, hepatic Fe was significantly increased while Cu, Zn and Ca levels were reduced, but still higher than those of control and Vit A-treated mice. In the kidney of Vit A + Ni treated mice, the increase of Cu, Fe, and Zn but not Ca, was reduced and not significantly different from control and Vit A-treated mice. Pretreatment with Vit A reduced the increased Fe, Cu, Zn and Ca concentration in the lung caused by Ni injection. We therefore conclude that the effect of Vit A pretreatment on Ni toxicity is organ-dependent.

Analysis of Variance↗

PubMed1998

Multinuclear NMR resonance assignments and the secondary structure of Escherichia coli thioesterase/protease I: a member of a new subclass of lipolytic enzymes.

Escherichia coli thioesterase/protease I is a 183 amino acid protein with a molecular mass of 20,500. This protein belongs to a new subclass of lipolytic enzymes of the serine protease superfamily, but with a new GDSLS consensus motif, of which no structure has yet been determined. The protein forms a tetramer at pH values above 6.5 and exists as a monomer at lower pH values. Both monomer and tetramer are catalytically active. From analysis of a set of heteronuclear multidimensional NMR spectra with uniform and specific amino acid labeled protein samples, we have obtained near-complete resonance assignments of the backbone 1H, 13C and 15N nuclei (BMRB databank accession number 4060). The secondary structure of E. coli thioesterase/protease I was further deduced from the consensus chemical shift indices, backbone short- and medium-range NOEs, and amide proton exchange rates. The protein was found to consist of four beta-strands and seven alpha-helices, arranged in alternate order. The four beta-strands were shown to form a parallel beta-sheet. The topological arrangement of the beta-strands of -1x, +2x, +1x appears to resemble that of the core region of the alpha beta hydrolase superfamily, typically found in common lipases and esterases. However, substantial differences, such as the number of beta-strands and the location of the catalytic triad residues, make it difficult to give a definitive classification of the structure of E. coli thioesterase/protease I at present.

Amino Acid Sequence↗

PubMed1998

Home-based resistance training: predictors of participation and adherence.

This study identified factors associated with exercise participation and adherence in a sample of 102 sedentary, functionally limited, community-dwelling adults aged 60 to 94 years who participated in a home-based resistance training program. Stepwise regression analyses revealed that baseline physical factors (i.e., higher levels of mobility, weaker muscle strength, and fewer numbers of new medical conditions) were associated with higher rates of participation in the home program. Positive attitudes and a sense of control toward exercise, lower levels of confusion and depressive moods, and the development of fewer new medical problems during the program were related to higher levels of adherence to the program. Findings revealed that although physical health variables were the primary indicators of an older person's overall participation in the program, it was the psychological factors that were most important to adherence to this home-based program.

Aged↗

PubMed1998

Surveillance of anti-hantavirus antibodies among certain high-risk groups in Taiwan.

Hemorrhagic fever with renal syndrome is a serious health concern in neighboring countries of Taiwan, such as mainland China and Korea. In Taiwan, only two suspected cases were recorded before 1994. The first confirmed case was reported in 1995, but this proved to be imported. To study hantavirus infection in Taiwan, we tested blood collected from garbage collectors, animal handlers, patients with febrile illness of unknown origin, and field rats, the host of hantavirus, for the presence of antibody against hantavirus using an indirect immunofluorescent antibody technique. The positive rates were 1.55% (3/193), 3.45% (1/29), 1.42% (3/211), and 5.56% (9/162), respectively. The subtypes of hantavirus involved were either Hantaan-like or Seoul-like. These results showed that hantavirus may have already invaded Taiwan without our knowledge and physicians should be aware of this.

Adolescent↗

PubMed1998

Bilateral choroidal metastases as the initial presentation of a small breast carcinoma: a case report.

Most ocular tumors metastasize from systemic origins in breast carcinoma in females, and bronchial carcinoma in males. Here, we report a case of choroidal carcinoma metastasis from the breast with visual problems being the only initial manifestations. In this case, both eyes were involved at almost the same time, with initial manifestation of blurred vision which progressed to complete visual loss. At first, the patient was diagnosed with malignant melanoma, and enucleation of the right eye was performed in another hospital. However, the tumor had already metastasized rapidly to numerous organs, including the lungs, brain and bone, although it had not affected the liver. Clinical presentations were, therefore, not compatible with those of malignant melanoma, which has usually been reported to metastasize to the liver. Persistent hypercalcemia and raised carcinoembryonic antigen (CEA) concentrations prompted investigations into the possibility of systemic malignancy. A very small breast nodule was finally located by thorough physical examination, and a lumpectomy was performed. A detailed review of the histopathology showed the tumors from the breast and the right eye to have the same origin. Simultaneous bilateral choroidal metastases from other malignancies is not uncommon; however, it is quite rare for breast carcinoma to present with visual problems as a first manifestation. Detailed history taking and physical examination are therefore essential when searching for a primary tumor, so that appropriate therapy can be given earlier.

Adult↗

PubMed1998

Retinyl substituted-benzyl ethers. Inhibition of mammary carcinogenesis by retinyl 3,4,5-trimethoxybenzyl ether (RTMBE).

Recently, we reported that retinyl 2-propynyl ether (RPE) inhibits MNU-induced mammary cancer in rats and is less toxic than RME and retinyl acetate. The preparation and biological investigations of retinyl ethers have now been extended to retinyl substituted-benzyl ethers, some of which bind to cellular retinol-binding protein. In long-term (160-180 days) experiments, retinyl 3,4,5-trimethoxybenzyl ether (RTMBE) has been shown to be active against MNU-induced mammary cancer in Sprague-Dawley rats. In effectiveness, RTMBE is comparable, at least, to retinyl acetate; but, unlike retinyl acetate, RTMBE is comparatively non-toxic to rats and mice, is not converted enzymatically to retinol, and does not cause significant increases in retinyl palmitate concentrations in the liver. RTMBE reaches high concentrations in mammary tissue. Two of the four RTMBE congeners that were evaluated in 90 day studies were moderately effective in inhibiting mammary carcinogenesis.

Administration, Oral↗

PubMed1998

Pre-analytical for biological monitoring of manganese.

Manganese is an essential element but it may result in a toxic event if the workers are excessively exposed to this element. Monitoring of biological Mn exposure is therefore important. The careful preparation for Mn analysis is necessary. In order to get a correct protocol for sampling and storage of the biological samples, identification of the possible contamination source is necessary. This study is concerned with the monitoring procedure of manganese especially the sources of contamination sampling, sample transportation and storage. The results of the study shows that some kinds of needles and anticoagulants might be the main sources of contamination of specimen. It is important to avoid these contamination in performing biological monitoring on workers exposed to manganese.

Environmental Monitoring↗

PubMed1998

[The density and larval habitats of dengue vectors in Chungho city].

A survey was conducted to understand larval habitats and density of dengue vectors in Chungho city during the period of August 12 to September 13, 1996. Most villages (41 in the total of 93) were found to have the density figures of three for Aedes albopictus Skuse. The second common density figures were found at 2nd and 4th levels. The most common breeding containers found were less than 5 cm in water depth and less than 100 cm2 in water area. The number of breeding containers reduced when the water depth and size increased. The common breeding containers in villages were flower vases (30%) and water buckets (18%). In the mountains, water buckets (34%) and kitchen tools (11%) were common. In parks, water buckets (29%) and tires (15%) were commonly found. In cemeteries, the common breeding containers were flower vases (57%) and earthenware pots (17%). The average (2.05 containers per man-hour) of positive water containers in the mountains was significantly higher than that in parks (0.62). However, the average in cemeteries (1.29) was not significantly different from those collected in mountains and parks.

Aedes↗

PubMed1997

Cell anchorage permits efficient signal transduction between ras and its downstream kinases.

Cell anchorage strongly affects the signal transduction cascade initiated by peptide mitogens. For both epidermal growth factor and platelet-derived growth factor, activation of the consensus mitogen-activated protein kinase cascade is impaired when cells are held in suspension as compared with cells anchored to a fibronectin substratum. Upstream events in the signaling cascade, including tyrosine phosphorylation of the mitogen receptor and GTP loading of Ras, are similar in anchored and suspended cells. However, propagation of the signal to Raf and subsequently to the downstream kinases MEK and mitogen-activated protein kinase is markedly attenuated in suspended cells. Thus, there seems to be a distinct anchorage-dependent step between Ras and Raf in the signaling cascade initiated by peptide mitogens. These observations may have important implications for understanding the anchorage dependence of cell growth.

3T3 Cells↗

PubMed1997

Integrin-mediated activation of MAP kinase is independent of FAK: evidence for dual integrin signaling pathways in fibroblasts.

Integrin-mediated cell adhesion causes activation of MAP kinases and increased tyrosine phosphorylation of focal adhesion kinase (FAK). Autophosphorylation of FAK leads to the binding of SH2-domain proteins including Src-family kinases and the Grb2-Sos complex. Since Grb2-Sos is a key regulator of the Ras signal transduction pathway, one plausible hypothesis has been that integrin-mediated tyrosine phosphorylation of FAK leads to activation of the Ras cascade and ultimately to mitogen activated protein (MAP) kinase activation. Thus, in this scenario FAK would serve as an upstream regulator of MAP kinase activity. However, in this report we present several lines of evidence showing that integrin-mediated MAP kinase activity in fibroblasts is independent of FAK. First, a beta1 integrin subunit deletion mutant affecting the putative FAK binding site supports activation of MAP kinase in adhering fibroblasts but not tyrosine phosphorylation of FAK. Second, fibroblast adhesion to bacterially expressed fragments of fibronectin demonstrates that robust activation of MAP kinase can precede tyrosine phosphorylation of FAK. Finally, we have used FRNK, the noncatalytic COOH-terminal domain of FAK, as a dominant negative inhibitor of FAK autophosphorylation and of tyrosine phosphorylation of focal contacts. Using retroviral infection, we demonstrate that levels of FRNK expression sufficient to completely block FAK tyrosine phosphorylation were without effect on integrin-mediated activation of MAP kinase. These results strongly suggest that integrin-mediated activation of MAP kinase is independent of FAK and indicate the probable existence of at least two distinct integrin signaling pathways in fibroblasts.

3T3 Cells↗

PubMed1997

A contact scoring matrix for qualitative prediction of change in folding of alpha-helices in globular proteins caused by a mutation.

The atomic pairs in contact for atoms from pairs of amino-acid residues on pairs of helices in a protein database consisting of 48 proteins of known tertiary structure from the Brookhaven Protein Data Bank are searched and counted to construct a primary scoring system. Each score in the primary scoring system is weighted further with the possibility of occurrence of each residue pair in the protein database to give a final scoring matrix. Scores for predicting change in folding of alpha-helices in a mutant protein are calculated by assuming that every pair of helices in the protein can closely interact with each other. It is shown that the change in folding of alpha-helices in several mutant proteins are reflected in both the change of the contact scores and the helix geometry calculated.

Databases, Factual↗

PubMed1997

Metabolism of 14C-labelled sucrose esters of stearic acid in rats.

Rats were dosed by oral gavage (250 mg/kg) with compounds containing sucrose esterified in four, six or eight positions with stearic acid. For each compound, rats excreted greater than 95% of the dose in the faeces. The extent of absorption and metabolism of radioactivity was inversely related to the degree of esterification. For rats dosed with sucrose esters labelled in the fatty acid moieties, the degree of absorption of radioactivity was highest for the tetraesterified compound (5.9% of the dose). At 120 hr after dosing with this derivative, the highest concentrations of radioactivity, aside from tissues of the gastrointestinal tract, were found in fat (183 micrograms-equivalents/g tissue), lymph nodes (117 micrograms-equivalents/g tissue) and the liver (88 micrograms-equivalents/g tissue); appreciable radioactivity appeared in the blood (3.9 micrograms-equivalents/g tissue) and collected lymph (5.0-7.6% of the dose). For rats dosed with esters labelled in the sucrose moiety, the amounts of radioactivity absorbed were lower than after dosing with the corresponding sucrose derivatives labelled in the fatty acid moieties; the absorbed radioactivity was greatest following administration of the tetraesterified compound (3.0%). Relatively little radioactivity was found in tissue samples collected from these rats. These results are consistent with limited hydrolysis of the sucrose esters, presumably to sucrose and fatty acids, prior to intestinal absorption.

Administration, Oral↗