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Biomedical subjects

T J Lin

Publications and source records attributed to T J Lin.

At least 19 recordsLinked to original sources

An aqueous Chlorella extract inhibits IL-5 production by mast cells in vitro and reduces ovalbumin-induced eosinophil infiltration in the airway in mice in vivo.

An aqueous extract of the edible microalga (CP) (1), has recently been tested for its immunomodulatory effects in a human clinical trial. Here, the CP extract was dialyzed and fractionated using Sephadex G 100 chromatography. The effects of a dialyzed aqueous CP extract, fraction 2 , on mast cell mediator release in vitro and ovalbumin-induced allergic airway inflammation in vivo were examined. In vitro, treatment of mouse bone marrow-derived mast cells with 2 for 18 h significantly inhibited antigen (trinitrophenyl-BSA)-induced IL-5 production. In vivo, treatment of mice with 2 during ovalbumin sensitization and stimulation process significantly reduced eosinophil and neutrophil infiltration in the airways. Moreover, fractions obtained by size exclusion chromatography of 2 inhibited IgE-dependent cytokine GM-CSF production from human cord blood-derived mast cells. Taken together, these results suggest that 2 is composed of biopolymers with anti-allergic potential.

Animals↗

Adult reserve stem cells and their potential for tissue engineering.

Tissue restoration is the process whereby multiple damaged cell types are replaced to restore the histoarchitecture and function to the tissue. Several theories have been proposed to explain the phenomenon of tissue restoration in amphibians and in animals belonging to higher orders. These theories include dedifferentiation of damaged tissues, transdifferentiation of lineage-committed progenitor cells, and activation of reserve precursor cells. Studies by Young et al. and others demonstrated that connective tissue compartments throughout postnatal individuals contain reserve precursor cells. Subsequent repetitive single cell-cloning and cell-sorting studies revealed that these reserve precursor cells consisted of multiple populations of cells, including tissue-specific progenitor cells, germ-layer lineage stem cells, and pluripotent stem cells. Tissue-specific progenitor cells display various capacities for differentiation, ranging from unipotency (forming a single cell type) to multipotency (forming multiple cell types). However, all progenitor cells demonstrate a finite life span of 50 to 70 population doublings before programmed cell senescence and cell death occurs. Germ-layer lineage stem cells can form a wider range of cell types than a progenitor cell. An individual germ-layer lineage stem cell can form all cells types within its respective germ-layer lineage (i.e., ectoderm, mesoderm, or endoderm). Pluripotent stem cells can form a wider range of cell types than a single germ-layer lineage stem cell. A single pluripotent stem cell can form cells belonging to all three germ layer lineages. Both germ-layer lineage stem cells and pluripotent stem cells exhibit extended capabilities for self-renewal, far surpassing the limited life span of progenitor cells (50-70 population doublings). The authors propose that the activation of quiescent tissue-specific progenitor cells, germ-layer lineage stem cells, and/or pluripotent stem cells may be a potential explanation, along with dedifferentiation and transdifferentiation, for the process of tissue restoration. Several model systems are currently being investigated to determine the possibilities of using these adult quiescent reserve precursor cells for tissue engineering.

Animals↗

The chelating treatment is not useful in human's intoxication with acute herbicidal organic arsenic.

The clinical manifestations of acute organic arsenic intoxication in humans have seldom been described and the associated treatment has been thought to be the same as that of acute inorganic arsenic intoxication. We have studied a collection of patients from 1996 to 2001 who called the Poison Control Center of Kaohsiung Medical University Hospital asking for information regarding acute organic arsenic intoxication. The 17 patients ranged in age from 23 to 64 years old, with 5 females and 12 males. The cause of arsenic ingestion was attempted suicide. Abdominal pain and vomiting were the main symptoms. There were no differences in results between patients treated with and those treated without chelating agents. We therefore believe that the results of acute organic intoxication are not same as acute inorganic intoxication and it is unnecessary to use chelating agents in such conditions.

Acute Disease↗

Fatal poisoning by butachlor and chlornitrofen ingested from a bottle marked as nitrofen.

Nitrofen has been banned in Taiwan since January 1, 1983 due to its tetrogenicity. A 78-y-o female consumed about 500 ml of herbicide, labeled as nitrofen, in a suicide attempt. Consciousness disturbance occurred immediately. After 9 h, bloody-tarry stool was noted. Hematemesis occurred 19 h later. Hepatotoxicity and nephrotoxicity also developed. Twitching of head and both upper extremities lasting 20-30 sec and up to 5 min developed on day 3. Sometimes an upward gaze with the face turned to the right or a convulsion of the right upper extremity was observed. EEG showed alpha coma, generalized slow spike-and-wave complexes, and isolated generalized sharp waves mainly in the left occipital area. On day 7, endotracheal intubation was performed due to apnea; she expired on day 9. The pesticide was found to contain butachlor and chlornitrofen. The Agricultural Committee prohibited the marketing of chlornitrofen due to its generation of tumors in animals. The combination of butachlor and chlornitrofen can result in consciousness disturbance, leucocytosis, gastrointestinal hemorrhage, rhabdomyolysis, hypocalcemia, hypoalbuminemia, elevated amylase, nephrotoxicity, hepatotoxicity, seizures and death. The cytotoxicity of butachlor may be related to the patient's death. Active components of pesticides should be checked if the clinical course of a poisoned patient is unusual to allow appropriate interventions.

Acetanilides↗

Two episodes of ethylene oxide poisoning--a case report.

Ethylene oxide is used as a sterilizer, a solvent, a plasticizer and in the manufacture of special solvents, antifreeze, polyester resins and non-ionic surfactants. Its toxicity is caused by an alkylating reaction with most organic substances in the body. Four workers, without any protection, managed the leakage of ethylene oxide from the collecting tank improperly on July 29, 2000. In the same factory, the overflow of ethylene oxide in process resulted in leakage of ethylene oxide again on Aug. 7, 2000. Two workers were poisoned despite wearing full-face respirators with ethylene oxide approved canisters. In these two events, the workers all smelled an ether-like odor. Six workers experienced nausea, vomiting, chest tightness, shortness of breath, dizziness, cough and ocular irritation. One worker had transient loss of consciousness. Oxygen therapy and supportive care were used. Patients were discharged in stable condition. The permissible exposure limit of ethylene oxide in air is 1 ppm as an eight hour TWA. Above 50 ppm, the odor threshold, a positive-pressure supplied air respirator is needed to protect the worker. Full-face respirators with ethylene oxide approved canisters could not protect our cases who smelled the odor and were exposed to an unknown concentration. It is important to wear positive-pressure self-contained breathing apparatuses equipped with full facepieces to clean up the contamination area and rescue the patients.

Adult↗

Toll-like receptor 4-mediated activation of murine mast cells.

Toll-like receptors (TLRs) are a family of pattern recognition receptors that are critical for cellular responses to a variety of bacterial, viral, and fungal products. Mast cells are important to host survival in a number of models of bacterial infection and might act as sentinel cells in host defense. We therefore examined the expression of TLRs and associated molecules by murine bone marrow-derived mast cells (BMMCs). BMMCs and the murine mast cell line MC/9 expressed mRNA for TLR2, TLR4, and TLR6 but not TLR5 and for both adapter molecule MD-2 and signaling molecule MyD88 but lacked surface CD14. After activation with the TLR2- and TLR4-dependent stimuli Staphylococcus aureus-derived peptidoglycan and Escherichia coli-derived lipopolysaccharide (LPS), respectively, mast cells produced significant levels of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha). To determine whether mast cells require TLR4 for cellular responses to LPS, mast cells were derived from the bone marrow cells of C3H/HeJ and C57Bl/10ScNCr mice containing a point mutation and a null mutation, respectively, in TLR4. Using these models, we demonstrated that the BMMC IL-6 and TNF-alpha responses to LPS were completely dependent on functional TLR4 with no significant LPS response observed in its absence. These findings have important implications for the mechanism of mast cell responses to pathogens and their products and suggest that different TLR4-expressing cells might have different thresholds for activation with LPS.

Animals↗

Pancytopenia, hyperglycemia, shock, coma, rhabdomyolysis, and pancreatitis associated with acetaminophen poisoning.

It is well recognized that acetaminophen overdose can cause severe hepatic injury. However, extra-hepatic manifestations may also develop following inappropriate use or ingestion of large amounts of acetaminophen. We present a 44-y-o female who manifested coma, metabolic acidosis, shock, hypothermia, hyperglycemia, rhabdomyolysis, hepatotoxicity, and renal insufficiency after suicidal ingestion of an unknown amount of acetaminophen. Although her consciousness and hemodynamic status gradually improved after treatment with N-acetylcysteine and other supportive measures, she was found to have pancytopenia, pancreatitis and hepatorenal failure during the hospitalization and eventually died 18 d post-admission. Review of relevant literature reports and the clinical findings in our patient suggests that direct toxic effects mediated by acetaminophen or its metabolites were most likely responsible for most of the observed clinical features.

Acetaminophen↗

Human mast cells transmigrate through human umbilical vein endothelial monolayers and selectively produce IL-8 in response to stromal cell-derived factor-1 alpha.

Mature mast cells are generally considered to be less mobile cells residing within tissue sites. However, mast cell numbers are known to increase in the context of inflammation, and mast cells are recognized to be important in regulating local neutrophil infiltration. CXC chemokines may play a critical role in this process. In this study two human mast cell-like lines, HMC-1 and KU812, and human cord blood-derived primary cultured mast cells were employed to examine role of stromal cell-derived factor-1 (SDF-1) in regulating mast cell migration and mediator production. It was demonstrated that human mast cells constitutively express mRNA and protein for CXCR4. Stimulation of human mast cells with SDF-1, the only known ligand for CXCR4, induced a significant increase in intracellular calcium levels. In vitro, SDF-1 alpha mediated dose-dependent migration of human cord blood-derived mast cells and HMC-1 cells across HUVEC monolayers. Although SDF-1 alpha did not induce mast cell degranulation, it selectively stimulated production of the neutrophil chemoattractant IL-8 without affecting TNF-alpha, IL-1beta, IL-6, GM-CSF, IFN-gamma, or RANTES production, providing further evidence of the selective modulation of mast cell function by this chemokine. These findings provide a novel, SDF-1-dependent mechanism for mast cell transendothelial migration and functional regulation, which may have important implications for the local regulation of mast cells in disease.

Animals↗

Activation of macrophage CD8: pharmacological studies of TNF and IL-1 beta production.

Previously, we demonstrated that rat macrophages express CD8 and that Ab to CD8 stimulates NO production. We confirm that CD8 is expressed by rat macrophages and extend understanding of its functional significance. Activation of CD8 alpha (OX8 Ab) on alveolar macrophages stimulated mRNA expression for TNF and IL-1 beta and promoted TNF and IL-1 beta secretion. Similarly, OX8 Ab (CD8 alpha) stimulated NR8383 cells to secrete TNF, IL-1 beta, and NO. Activation of CD8 beta (Ab 341) on alveolar macrophages increased mRNA expression for TNF and IL-1 beta and stimulated secretion of TNF, but not IL-1 beta. Interestingly, anti-CD8 Abs did not stimulate IFN-gamma or PGE2 production, or phagocytosis by macrophages. OX8 (CD8 alpha)-induced TNF and IL-1 beta production by macrophages was blocked by inhibitors of protein tyrosine kinase(s), PP1, and genistein, but not by phosphatidylinositol-3 kinase inhibitor, wortmannin. Moreover, OX8 stimulated protein tyrosine kinase activity in NR8383 cells. Further analysis of kinase dependence using antisense to Syk kinase demonstrated that TNF, but not IL-1 beta, stimulation by CD8 alpha is Syk dependent. By contrast, protein kinase C inhibitor Ro 31-8220 had no effect on OX8-induced TNF production, whereas OX8-induced IL-1 beta production was blocked by Ro 31-8220. Thus, there are distinct signaling mechanisms involved in CD8 alpha (OX8)-induced TNF and IL-1 beta production. In summary, macrophages express CD8 molecules that, when activated, stimulate TNF and IL-1 beta expression, probably through mechanisms that include activation of Src and Syk kinases and protein kinase C. These findings identify a previously unknown pathway of macrophage activation likely to be involved in host defense and inflammation.

Androstadienes↗

Redundancy or cell-type-specific regulation? Tumour necrosis factor in alveolar macrophages and mast cells.

Tumour necrosis factor (TNF) is an important inflammatory cytokine produced by several cell types. To test the hypothesis that there is cell-type-specific regulation and not redundancy of TNF production, we investigated its production by alveolar macrophages (AM) and peritoneal mast cells (PMC). Cell lysates of freshly isolated AM and PMC contained 9 +/- 3 pg and 57 +/- 17 pg of TNF/10(6) cells, respectively. Furthermore, unstimulated PMC expressed 4 x 10(3)-fold more attomols of TNF mRNA/microg total RNA compared with AM. These data may explain in part the greater TNF-dependent cytotoxicity of PMC. Furthermore, fixed PMC showed significantly higher TNF-dependent cytotoxic activity than AM (sevenfold), suggesting that PMC express more membrane TNF than AM. Although AM and PMC contain different amounts of TNF, antigen stimulation caused a similar release of TNF from sensitized rats. Interferon (IFN)-gamma, respectively, stimulated and inhibited AM and PMC TNF-dependent cytotoxicity whereas lipopolysaccharide (LPS) significantly stimulated TNF-dependent cytotoxicity in both cell types. However, TNF released (AM 400-fold and PMC threefold) and TNF mRNA expression, as measured by competitive reverse transcription-polymerase chain reaction (AM 7 x 10(3)-fold and PMC twofold), were considerably greater in LPS-stimulated AM than PMC. Our data indicate that TNF is differentially expressed in these two cell types and that its production is dependent on the nature of the stimulus. These data provide vital basis in experimental approaches aimed at modulating the effect of TNF in airway disease conditions involving both AM and mast cells.

Animals↗

Internalization of FimH+ Escherichia coli by the human mast cell line (HMC-1 5C6) involves protein kinase C.

Rodent mast cells (MC) play critical roles in host defense against bacterial infection. However, bacteria-mediated signaling mechanisms in MC have not been studied. In addition, the response of human MC to bacteria is not fully investigated. This study examined the interaction between human MC and type 1 fimbriated Escherichia coli and the mechanisms involved using the human MC line HMC-1 5C6 and human cord blood-derived MC. These MC internalized significant numbers of FimH+ E. coli, but not its isogenic FimH- mutant. In HMC-1 cells, bacterial internalization was stimulated by protein kinase C (PKC) activation [short-term phorbol myristate acetate (PMA) treatment] and dramatically decreased by PKC inhibitors or PKC depletion (long-term PMA treatment). Moreover, bacterial internalization was accompanied by significant expression of PKCbeta1 and delta. Fluorescence microscopy demonstrated accumulation of PKCbeta1 on internalized bacteria. These data indicate that human MC has the capacity to internalize bacteria and PKC may be a critical intracellular mediator of this function.

Adhesins, Bacterial↗

Acute basagran poisoning mimicking neuroleptic malignant syndrome.

A 27-year-old robust man, without any medical and surgical history, attempted to commit suicide by consumption of 300 cc (44.1%, 132.3 g) basagran, a readily available herbicide. This poisoning resulted in vomiting, fever, sweating, pipe-like muscle rigidity, sinus tachycardia, drowsiness, leukocytosis, rhabdomyolysis and hepatorenal damage. Emperical treatment with bromocriptine was temporally associated with resolution of above signs and symptoms. His clinical presentations and the effect of bromocriptine may be indicative that basagran poisoning mimicks neuroleptic malignant syndrome.

Adult↗

Clinical impact of upper gastrointestinal tract injuries in glyphosate-surfactant oral intoxication.

Fifty patients with glyphosate-surfactant oral ingestion were studied with upper gastrointestinal (UGI) endoscopic grading using Zargar's modified grading system for mucosal corrosive injury. Esophageal injury was seen in 68% of the patients, gastric injury in 72%, and duodenal injury in 16%. There were no grade 3 injuries. The upper gastrointestinal tract injuries caused by glyphosate-surfactant were minor in comparison with those by other strong acids. The WBC count, amount of glyphosate-surfactant ingested, length of hospital stay and the occurrence of serious complications increased markedly in the group which had grade 2 esophageal injuries. Thus, the severity of the esophageal injuries may be a prognostic factor for the patient with glyphosate-surfactant ingestion. The UGI endoscopy may be indicated for grading esophageal injury in patients who have ingested glyphosate-surfactant in amounts greater than 100 ml. Physicians should pay more attention to the patients with grade 2 or 3 esophageal injuries to prevent serious complications and to provide aggressive supportive care.

Administration, Oral↗

Acute paraquat intoxication: using nuclear pulmonary studies to predict patient outcome.

STUDY OBJECTIVES: Paraquat, a widely used herbicide, has been shown to cause severe and often fatal pulmonary fibrosis in humans and laboratory animals. Although paraquat is known to be directly cytotoxic to lung parenchyma, changes in routine lung scintigraphy results after acute paraquat intoxication have not been reported. The objective of this project was to investigate changes in lung ventilation (LV) and alveolar permeability (AP) in patients with paraquat intoxication, using 99mTc diethylenetriamine pentaacetate (DTPA) radioaerosol lung scintigraphy. DESIGN: Prospective, blinded study. SETTING: Nuclear medicine and toxicology departments in two university-affiliated teaching hospitals. PATIENTS OR PARTICIPANTS: Thirteen patients with acute paraquat intoxication were included in this study. Ten volunteers without acute paraquat intoxication were studied for comparison. MEASUREMENTS AND RESULTS: 99mTc DTPA aerosol inhalation and 99mTc macroaggregated albumin (MAA) perfusion lung scintigraphies were performed to determine LV, AP, and lung perfusion (LP). Five of the 13 patients (38%) had significant LV abnormalities; 3 of these 5 patients also showed abnormal LP. Of the 13 patients, 4 patients (31%) showed normal AP and survived. The remaining 9 patients (69%) showed abnormal AP and died. The mean values for AP were statistically different (p < 0.01) between survivor (0.72 +/- 0.16%) and nonsurvivor (1.52 +/- 0.40%) groups. Data from the normal volunteers and survival patients showed a 99mTc clearance slope < 1.00%. Data from patients who died showed a clearance slope > 1.00%. CONCLUSION: These results indicate that AP, measured by 99mTc DTPA aerosol inhalation lung scintigraphy, may help predict outcome in patients with paraquat intoxication.

Acute Disease↗

Mast cells express novel CD8 molecules that selectively modulate mediator secretion.

CD8, a marker largely restricted to subsets of T lymphocytes and NK cells, was detected on freshly isolated rat peritoneal mast cells (PMC). Using flow cytometry, Percoll-enriched rat PMC (> or = 98% purity) were positive for the hinge region of CD8alpha (67.5 +/- 9.5%; Ab OX8) and CD8beta (27.8 +/- 2.3%; Ab 341). CD8+ PMC consisted of two populations, CD8alpha+ (22.5%) and CD8alpha+ beta+ (15.9%). Interestingly, G28, an Ab that identifies the IgV-like region of CD8alpha on T lymphocytes, did not bind PMC, suggesting that PMC CD8alpha is distinct from that on T lymphocytes. Moreover, a similar pattern of Ab positivity for CD8 was observed on a rat mast cell line, RBL 2H3. The presence of CD8alpha immunoreactivity on rat PMC was further confirmed by confocal microscopy. In situ reverse-transcription PCR and reverse-transcription PCR analysis demonstrated that PMC contained mRNA transcripts encoding CD8alpha. In functional studies of CD8 on PMC, both TNF-alpha and nitric oxide production were induced by OX8 (CD8alpha) and 341 Ab (CD8beta) in a dose-dependent manner. However, neither OX8 nor 341 induced histamine secretion from PMC. Ag-induced secretion of TNF-alpha, nitric oxide, and histamine was not affected by OX8 or 341 Abs, suggesting that there are distinct signaling mechanisms mediated by CD8 and Fc epsilonRI. These results indicate that rat PMC express functional CD8 molecules that may be distinct from those of T lymphocytes. The difference suggests there is a ligand other than MHC class I for mast cell CD8.

Animals↗

Mechanisms of macrophage stimulation through CD8: macrophage CD8alpha and CD8beta induce nitric oxide production and associated killing of the parasite Leishmania major.

Prior studies demonstrated that rat macrophages express CD8, which differs from T lymphocyte CD8 within the ligand binding domain. We investigated whether stimulation of macrophage CD8 could induce mediator release and regulate host defense. Cross-linking either CD8alpha (OX8, 5 microg/ml) or CD8beta (341, 10 microg/ml) stimulated nitric oxide (NO) production, which correlated with an up-regulation of inducible NO synthase protein. Cell signaling inhibitors were used to elucidate the pathways of CD8alpha and CD8beta stimulation. Genistein (broad spectrum protein tyrosine kinase inhibitor, 10 microg/ml), PP1 (src family kinase inhibitor, 5 microg/ml), polymyxin B (protein kinase C (PKC) inhibitor, 100 microg/ml), and Ro 31-8220 (PKC inhibitor, 1 microM) significantly inhibited anti-CD8alpha- and anti-CD8beta-stimulated NO production and inducible NO synthase up-regulation, suggesting that tyrosine kinase(s) (src family) and PKC are involved in CD8 signaling. In addition, cross-linking CD8alpha stimulated NO-dependent macrophage killing of the parasite Leishmania major. For the first time, this work demonstrates that the beta-chain of macrophage CD8, in addition to the alpha-chain, can regulate mediator release. These results further illustrate the importance of this molecule and support our previous data demonstrating differences between macrophage and T lymphocyte CD8. Additional studies on the signaling mechanisms and possible ligand(s) for macrophage CD8 will lead to a greater understanding of inflammation and host defense.

Animals↗

Effects of toxin A from Clostridium difficile on mast cell activation and survival.

Toxins A and B from Clostridium difficile are the main cause of antibiotic-associated diarrhea and pseudomembranous colitis. They cause fluid accumulation, necrosis, and a strong inflammatory response when inoculated in intestinal loops. Since mast cells are a rich source of inflammatory mediators, abundant in the gut, and known to be involved in C. difficile-induced enteritis, we studied the in vitro effect of toxin A on isolated mast cells. Normal rats sensitized by infection with Nippostrongilus brasiliensis were used to isolate peritoneal mast cells (PMC). PMC from naive rats were stimulated with calcium ionophore A23187 as a model of antigen-independent activation, and PMC from sensitized rats were stimulated with N. brasiliensis antigens to study immunoglobulin E-dependent mast cell activation. After 4 h, toxin A did not induce release of nitric oxide or histamine in naive PMC. However, 10 ng of toxin per ml caused a significant release of tumor necrosis factor alpha (TNF-alpha). In contrast, 1 microg of toxin per ml inhibited antigen or A23187-induced histamine release by PMC. Toxin A at 1 microg/ml for 4 h caused disruption of actin which aggregated in the cytoplasm and around the nucleus. After 24 h, chromatin condensation, cytoplasmic blebbing, and apoptotic-like vesicles were observed; DNA fragmentation was documented also. These results suggest that mast cells may participate in the initial inflammatory response to C. difficile infection by releasing TNF-alpha upon interaction with toxin A. However, longer exposure to toxin A affects the release of inflammatory mediators, perhaps because of the alteration of the cytoskeleton and induction of apoptosis. The impaired functions and survival of mast cells by C. difficile toxin A could hamper the capacity of these cells to counteract the infection, thus prolonging the pathogenic effects of C. difficile toxins.

Animals↗

Unique cerebral dysfunction following triphenyltin acetate poisoning.

1. In animal studies, TPTA was found to be neurotoxic. In humans, variable CNS pictures have been described with or without significant EEG findings. Brain CT does not usually reveal any abnormalities. 2. Our patient presented with intermittent unique spontaneous involuntary movement of hands, facial twitching, silly smile and crying. Diplopia, drowsiness, giddiness, vertigo, bidirectional nystagmus, impairment of calculation ability, as well as disorientation to time, people and place also developed. EEG showed mild cortical dysfunction without seizures. MRI and Tc-99m HMPAO brain SPECT revealed no significant findings. TPTA may cause cellular dysfunction of brain without structural damage, which results in variable CNS clinical presentations. 3. Nadir of leucopenia was noted on the sixth day after consumption of TPTA. Liver impairment occurred on the ninth day. Borderline demyelinated neuropathy developed on the fifty-third day. CNS abnormalities, delayed peripheral neuropathy, hepatitis and leucopenia deserve monitoring for a prolonged period, even when the victim initially presents with GI upset only after consumption of TPTA.

Adult↗