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Biomedical subjects

Y H Tsai

Publications and source records attributed to Y H Tsai.

At least 19 recordsLinked to original sources
PubMed2006

Determination of tetrodotoxin in human urine and blood using C18 cartridge column, ultrafiltration and LC-MS.

Six fishermen were victims (including one death) of food poisoning from unknown fish on their boat in central Taiwan Strait, in April 2001. The symptoms were like those of tetrodotoxin (TTX) poisoning. As there was no remaining fish, a new protocol was developed to determine TTX in the urine and blood of the victims. The urine and blood samples were cleansed using a C18 Sep-Pak cartridge column, and the toxin was extracted by methanol. The eluate was filtered through a microcentrifuge filter. The filtrate was freeze-dried, dissolved in distilled water, and determined by LC-MS. The recovery was more than 88.9%. The detection limit was 15.6 nM. A linear relationship between response and concentration was obtained between 93.75 and 9375 nM of TTX. It was shown that the urine and blood of the victims contained TTX. The range of TTX was 4.5-40.6 nM in blood and 47-344 nM in urine. Judging from the symptoms of the victims and the experimental data, the causative agent of the food poisoning was identified as TTX.

Adult↗
PubMed2005

Type I and II collagen regulation of chondrogenic differentiation by mesenchymal progenitor cells.

Chondrogenic differentiation by mesenchymal progenitor cells (MPCs) is associated with cytokines such as transforming growth factor-beta 1 (TGF-beta1) and dexamethasone. Extracellular matrix (ECM) also regulates the differentiation by MPCs. To define whether ECM plays a functional role in regulation of the chondrogenic differentiation by MPCs, an in vitro model was used. That model exposed to dexamethasone, recombinant human TGF-beta1(rhTGF-beta1) and collagens. The results showed that MPCs incorporated with dexamethasone and rhTGF-beta1 increased proliferation and expression of glycosaminoglycan (GAG) after 14 days. Type II collagen enhanced the GAG synthesis, but did not increase alkaline phosphatase (ALP) activity. When adding dexamethasone and rhTGF-beta1 MPCs increased mRNA expression of Sox9. Incorporation with type II collagen, dexamethasone and rhTGF-beta1, MPCs induced mRNA expression of aggrecan and enhanced levels of type II collagen, and Sox9 mRNA. In contrast, incorporation with type I collagen, dexamethasone and rhTGF-beta1 MPCs reduced levels of aggrecan, and Sox9 mRNA, and showed no type II collagen mRNA. Altogether, these results indicate that type I and II collagen, in addition to the cytokine effect, may play a functional role in regulating of chondrogenic differentiation by MPCs.

Aggrecans↗
PubMed2001

Evaluation of percutaneous absorption and skin irritation of ketoprofen through rat skin: in vitro and in vivo study.

The influences of different mechanisms of penetration enhancers (such as menthol, azone, ethanol and nonivarnide) regarding the percutaneous absorption and skin irritation of ketoprofen formulations through rat skin were investigated by in vitro and in vivo study. The skin irritation degree at the end of the experiment (10 h) was deterinined by pathologic biopsy and colorimetry methods. In vitro, the menthol showed the most potent enhancing effect. Furthermore, the enhancement effect of a combination of menthol and nonivamide was higher than that of their individual use alone. In vivo the formulation containing 0.05% nonivantide, 5% menthol and 20% ethanol showed a higher penetration rate and an acceptable degree of skin irritation compared to a commercial product (Formax plus gel containing 3% ketoprofen), indicating that it could be used in the clinical situation.

Animals↗
PubMed2001

In vitro skin permeation of estradiol from various proniosome formulations.

The skin permeation of estradiol from various proniosome gel formulations across excised rat skin was investigated in vitro. The encapsulation efficiency and size of niosomal vesicles formed from proniosomes upon hydration were also characterized. The encapsulation (%) of proniosomes with Span surfactants showed a very high value of about 100%. Proniosomes with Span 40 and Span 60 increased the permeation of estradiol across skin. Both penetration enhancer effect of non-ionic surfactant and vesicle-skin interaction may contribute to the mechanisms for proniosomes to enhance estradiol permeation. Niosome suspension (diluted proniosomal formulations) and proniosome gel showed different behavior in modulating transdermal delivery of estradiol across skin. Presence or absence of cholesterol in the lipid bilayers of vesicles did not reveal difference in encapsulation and permeation of the associated estradiol. The types and contents of non-ionic surfactant in proniosomes are important factors affecting the efficiency of transdermal estradiol delivery.

Cellulose↗
PubMed2001

Cytotoxicity and immunogenicity of SACCHACHITIN and its mechanism of action on skin wound healing.

SACCHACHITIN membrane, a weavable skin substitute made from the residual fruiting body of Ganoderma tsugae, has been demonstrated to promote skin wound healing. Prior to its clinical application, it is critical to learn more about any possible cytotoxicity, immunogenicity, or allergy response, and at least some of its mechanism(s) of action(s). In the present studies, it has been found that SACCHACHITIN suspension at less than 0.05% shows no cytotoxicity to the primary culture of rat fibroblasts. However, at higher concentrations (> or = 0.1%), it does reduce the growth of fibroblasts, based on MTT assays. This might be caused by positive charges on chitin molecules that are too strong, and may be harmful to the cell membrane. SACCHACHITIN showed no immunogenicity after it was inoculated into rats three times; however, the unmodified, purified rabbit type I and type II collagens did. Subcutaneous injection of SACCHACHITIN suspension into rats showed no gross allergic responses on skin. Nevertheless, it did cause local acute inflammation, as observed by histological investigation. This is similar to what occurred in the wound site covered with SACCHACHITIN membrane. The chemotactic effect of SACCHACHITIN was exhibited in both intact and wounded skin tissues. This may be one of the initial beneficial effects of SACCHACHITIN membrane to wound healing. The rapid acute inflammatory process was followed by the appearance of angiogenesis and granulation tissue formation, which occurred earlier than it normally would. Coverage of the wound area with SACCHACHITIN membrane also induced an earlier formation of scar tissue to replace the granulation tissue. A 1.5 x 1.5 cm(2) wound area covered by SACCHACHITIN completely healed by 21 days, while that covered with cotton gauze did not. Therefore, SACCHACHITIN is a safe biomaterial for use as a wound dressing for skin healing. Its promoting action for wound healing might be due to its chemotactic effect for inflammatory cells. This, in turn, may facilitate subsequent angiogenesis, granulation tissue formation, and faster new tissue formation, leading to faster wound healing.

Animals↗
PubMed2001

Effects of inverse ratio ventilation versus positive end-expiratory pressure on gas exchange and gastric intramucosal PCO(2) and pH under constant mean airway pressure in acute respiratory distress syndrome.

BACKGROUND: In patients with acute respiratory distress syndrome, whether inverse ratio ventilation differs from high positive end-expiratory pressure (PEEP) for gas exchange under a similar mean airway pressure has not been adequately examined. The authors used arterial oxygenation, gastric intramucosal partial pressure of carbon dioxide (PiCO(2)), and pH (pHi) to assess whether pressure-controlled inverse ratio ventilation (PC-IRV) offers more benefits than pressure-controlled ventilation (PCV) with PEEP. METHODS: Seventeen acute respiratory distress syndrome patients were enrolled and underwent mechanical ventilation with a PCV inspiratory-to-expiratory ratio of 1:2, followed by PC-IRV 1:1 initially. Then, they were randomly assigned to receive PC-IRV 2:1, then 4:1 or 4:1, and then 2:1, alternately. The baseline setting of PCV 1:2 was repeated between the settings of PC-IRV 2:1 and 4:1. Mean airway pressure and tidal volume were kept constant by adjusting the levels of peak inspiratory pressure and applied PEEP. In each ventilatory mode, hemodynamics, pulmonary mechanics, arterial and mixed venous blood gas analysis, PiCO(2), and pHi were measured after a 1-h period of stabilization. RESULTS: With a constant mean airway pressure, PC-IRV 2:1 and 4:1 decreased arterial and mixed venous oxygenation as compared with baseline PCV 1:2. Neither the global oxygenation indices with oxygen delivery and uptake nor PiCO(2) and pHi were improved by PC-IRV. During PC-IRV, applied PEEP was lower, and auto-PEEP was higher. CONCLUSION: When substituting inverse ratio ventilation for applied PEEP to keep mean airway pressure constant, PC-IRV does not contribute more to better gas exchange and gastric intramucosal PiCO(2) and pHi than does PCV 1:2 for acute respiratory distress syndrome patients, regardless of the inspiratory-to-expiratory ratios.

APACHE↗
PubMed2001

Gastric intramucosal PCO2 and pH variability in ventilated critically ill patients.

OBJECTIVE: Gastric intramucosal PCO2 (PiCO2) and pH (pHi) are currently used as indices of the adequacy of splanchnic perfusion and as end points to guide therapeutic intervention. However, little is known about their spontaneous variability over time. The present study was designed to define the magnitude of spontaneous variability of PiCO2 and pHi in sedated medical intensive care unit (ICU) patients using an automated recirculating air tonometer and to test whether high-level positive end-expiratory pressure (PEEP) or inverse inspiratory/expiratory (I:E) ratio ventilation resulted in a greater variability than low PEEP with conventional I:E ratio ventilation. DESIGN: Prospective study. SETTING: Medical ICU in a tertiary medical center. PATIENTS: Twenty-three acute respiratory failure patients. INTERVENTIONS: After being sedated, patients were randomized to undergo pressure control ventilation at the following three settings: A, high PEEP (15 cm H2O) with conventional I:E ratio (1:2), and B, low PEEP (5 cm H2O) with inverse I:E ratio (2:1) alternately, and then C, low PEEP (5 cm H2O) with conventional I:E ratio (1:2). Each ventilation setting period lasted 1 hr. MEASUREMENTS AND MAIN RESULTS: The PiCO2 and pHi were measured at baseline (time 0), and at 15, 30, 45, and 60 mins thereafter. The corresponding coefficients of variation (CVs) of PiCO2 for overall pooled group and settings A, B, and C were 4.0%, 4.4%, 3.4%, and 4.2%, respectively. The corresponding CVs of pHi for overall pooled group and settings A, B, and C were 0.36%, 0.37%, 0.33%, and 0.4%, respectively. Analysis of variance showed no significant difference in the CVs of PiCO2 or pHi between the three settings. The 95% confidence interval is approximately +/-8% variability for PiCO2 and +/-0.7% variability for pHi. CONCLUSIONS: In critically ill medical ICU patients with stable hemodynamics, the spontaneous variability of PiCO2 or pHi are not substantial. High PEEP (15 cm H2O) and inverse ratio ventilation (2:1), which does not change the cardiac output or hemodynamics, does not contribute to increased spontaneous variability in PiCO2 or pHi.

Adult↗
PubMed2001

Cellular response of antioxidant metalloproteins in Cu/Zn SOD transgenic mice exposed to hyperoxia.

Ceruloplasmin, metallothionein, and ferritin are metal-binding proteins with potential antioxidant activity. Despite evidence that they are upregulated in pulmonary tissue after oxidative stress, little is known regarding their influence on trace metal homeostasis. In this study, we have used copper- and zinc-containing superoxide dismutase (Cu/Zn SOD) transgenic-overexpressing and gene knockout mice and hyperoxia to investigate the effects of chronic and acute oxidative stress on the expression of these metalloproteins and to identify their influence on copper, zinc, and iron homeostasis. We found that the oxidative stress-mediated induction of ceruloplasmin and metallothionein in the lung had no effect on tissue levels of copper, iron, or zinc. However, Cu/Zn SOD expression had a marked influence on hepatic copper and iron as well as circulating copper homeostasis. These results suggest that ceruloplasmin and metallothionein may function as antioxidants independent of their role in trace metal homeostasis and that Cu/Zn SOD functions in copper homeostasis via mechanisms distinct from its superoxide scavenging properties.

Animals↗
PubMed2001

Dietary zinc supplementation inhibits NFkappaB activation and protects against chemically induced diabetes in CD1 mice.

Zinc status in patients with Type I diabetes is significantly lower than healthy controls. Whether zinc supplementation can prevent the onset of Type I diabetes is unknown. Recent studies have suggested that the generation of reactive oxygen species (ROS) is a cause of beta cell death leading to Type I diabetes. In addition, we found that activation of NFkappaB (a ROS-sensitive transcription factor that regulates immune responses) may be the key cellular process that bridges oxidative stress and the death of beta cells. Zinc is a known antioxidant in the immune system. Therefore, this study is designed to test whether an increase in dietary zinc can prevent the onset of Type I diabetes by blocking NFkappaB activation in the pancreas. The results show that high zinc intake significantly reduced the severity of Type I diabetes (based on hyperglycemia, insulin level, and islet morphology) in alloxan and streptozotocin-induced diabetic models. Zinc supplementation also inhibited NFkappaB activation and decreased the expression of inducible NO synthase, a downstream target gene of NFkappaB. It is concluded that zinc supplementation can significantly inhibit the development of Type I diabetes. The ability of zinc to modulate NFkappaB activation in the diabetogenic pathway may be the key mechanism for zinc's protective effect. Inhibition of the NFkappaB pathway may prove to be an important criterion for choosing nutritional strategies for Type I diabetes prevention.

Alloxan↗
PubMed2001

Influence of electrical and chemical factors on transdermal iontophoretic delivery of three diclofenac salts.

The aim of this present study was to investigate the in vitro transdermal iontophoretic delivery of three diclofenac salts--diclofenac sodium (DFS), diclofenac potassium (DFP), and diclofenac diethylammonium (DFD). A series of physicochemical and electrical variables which might affect iontophoretic permeation of diclofenac salts was studied. Application of 0.3 mA/cm2 current density significantly increased the transdermal flux of diclofenac salts as compared to passive transport. The iontophoretic enhancement increased in the order of DFS>DFP>DFD. The permeability coefficient of diclofenac salts all decreased with increasing donor concentration during iontophoresis. The addition of buffer ions and salt ions such as NaCl, KCl, and C4H12ClN reduced the permeation of diclofenac salts due to competition. However, this effect was lesser for DFD than for DFS and DFP. Comparing the various application modes of iontophoresis, the discontinuous on/off mode showed lower but more constant flux than the continuous mode.

Administration, Cutaneous↗
PubMed2000

Cost-effective screening methods for various single gene defects in single cells using high magnesium and total ionic strength and restriction enzymes.

A reliable cost-effective protocol for the diagnosis of various defective genes in single blastomeres from preimplantation embryos has been established. Single cells were lysed in alkali buffer followed by neutralization and addition of a solution containing a high concentration of sulfhydryl reducing agents and MgCl(2) in relatively high ionic strength (0.45) (solution M) with or without restriction enzyme(s). The reaction mixture was incubated at 37 degrees C for 15 min followed by heat denaturation at 95 degrees C for 10 min. Respective polymerase chain reaction (PCR) mixture was then added to amplify each designated DNA region. The treatment of neutralized single cell lysate with adequate restriction enzyme(s) which do not cleave the target DNA sequences but shortens the genomic template DNA strands. This may facilitate primer-template annealing. The subsequent heat denaturation of the cell lysate in solution M indeed gave better signals of amplified DNA fragments on polyacrylamide gels. Defects in Tay Sachs exons 11 and 12, CF-DeltaF508 and CF-N1303K, and genomic sequences of ZFX/ZFY were successfully detected on gels after one-step PCR amplification, especially those cell lysates treated with restriction enzymes. In conclusion, a cost-effective one-step PCR method for amplifying various specific genomic regions containing a single gene defect in single cells has been established. This protocol may be applied to genetic screening for many single defective genes of biopsied single blastomeres from preimplantation in vitro fertilization (IVF) embryos.

Blastocyst↗
PubMed2000

Hypokalemic muscular paralysis causing acute respiratory failure due to rhabdomyolysis with renal tubular acidosis in a chronic glue sniffer.

CASE REPORT: A 34-year-old male was admitted to the emergency department with the development of quadriparesis and respiratory failure due to hypokalemia after prolonged glue sniffing. The patient was subsequently given mechanical ventilatory support for respiratory failure. He was weaned from the ventilator 4 days later after potassium replacement. Toluene is an aromatic hydrocarbon found in glues, cements, and solvents. It is known to be toxic to the nervous system, hematopoietic system, and causes acid-base and electrolyte disorders. Acute respiratory failure with hypokalemia and rhabdomyolysis with acute renal failure should be considered as potential events in a protracted glue sniffing.

Acidosis, Renal Tubular↗
PubMed2000

Effects of fenoterol and ipratropium on respiratory resistance of asthmatics after tracheal intubation.

We have studied the effects of a beta-agonist, fenoterol, and a cholinergic antagonist, ipratropium, on post-intubation total respiratory system resistance (Rrs) in asthmatics who developed increased Rrs after tracheal intubation. Sixteen stable asthmatics in whom Rrs increased after intubation were allocated randomly to receive either 10 puffs of fenoterol (group F) or 10 puffs of ipratropium (group IB) via a metered dose inhaler 5 min after intubation. Anaesthesia was induced and maintained with propofol i.v. Rrs was recorded before treatment and again 5, 15 and 30 min after treatment. Rrs decreased significantly from pretreatment values by mean 53 (SD 8)%, 53 (7)% and 58 (6)% at 5, 15 and 30 min, respectively, in group F, but declined by only 12 (6)%, 15 (4)% and 17 (5)% in group IB. At all times after treatment, patients in the fenoterol group had significantly lower Rrs values than those in the ipratropium group. We conclude that increased Rrs after tracheal intubation in asthmatics can be reduced effectively by treatment with fenoterol. A secondary finding of our study was that even after induction of anaesthesia with propofol, patients with a history of asthma may develop high Rrs.

Adrenergic beta-Agonists↗
PubMed2000

Spontaneous variability of cardiac output in ventilated critically ill patients.

OBJECTIVE: To define the magnitude of spontaneous cardiac output variability over time in sedated medical intensive care unit patients attached to a continuous cardiac output monitor, and to determine whether high level positive end-expiratory pressure or inverse inspiratory-to-expiratory (I:E) ratio ventilation resulted in greater variability over time than low positive end-expiratory pressure with conventional I:E ratio ventilation. DESIGN: Prospective study. SETTING: Medical intensive care unit in a tertiary medical center. PATIENTS: A total of 22 hemodynamically stable acute respiratory failure patients with a pulmonary artery catheter inserted for hemodynamic monitoring INTERVENTIONS: After being sedated, patients were randomized ultimately to receive pressure control ventilation first at setting A (high positive end-expiratory pressure [15 cm H2O] with conventional I:E ratio [1:2]) and then at setting B (low positive end-expiratory pressure [5 cm H2O] with inverse I:E ratio [2:1]), or vice versa, and then at setting C (low positive end-expiratory pressure [5 cm H2O] with conventional I:E ratio [1:2]). Each ventilation setting period lasted 1 hr. MEASUREMENTS AND MAIN RESULTS: Cardiac output (CO) was measured continuously. The continuous CO value displayed was updated every 30-60 secs. The updated value reflected an average of the previous 3-6 mins. The coefficient of variation (CV) of CO for each setting in each patient was calculated to represent the spontaneous variability. The mean CO+/-SD and CV of each setting was 5.7+/-1.8 L/min and 4.4% for setting A, 5.6+/-1.5 L/min and 4.6% for setting B, and 5.9+/-1.7 L/min and 4.8% for setting C. Analysis of variance revealed no significant differences between the CVs of the three settings. The 95% confidence interval for the COs for each setting was approximately the mean CO+/-0.1 x mean CO measured. CONCLUSIONS: In critically ill sedated medical intensive care unit patients with stable hemodynamics, the spontaneous variability of cardiac output over time was not significant. High positive end-expiratory pressure (15 cm H2O) and inverse ratio ventilation (2:1) did not contribute to increased spontaneous variability of cardiac output.

APACHE↗
PubMed2000

Hyperkalemic cardiac arrest successfully reversed by hemodialysis during cardiopulmonary resuscitation: case report.

Severe hyperkalemia is a potential life-threatening cardiac emergency especially in the patients who suffer from a defective renal capacity to excrete potassium such as the dialysis patient. Various conventional therapies including intravenous sodium bicarbonate, insulin with glucose and several beta-2 agonists are commonly employed as transient measures to enhance shift of potassium from the extracellular to the intracellular compartment. If the potassium load is massive and situation is critical, emergency hemodialysis may be useful. During cardiopulmonary resuscitation, the external cardiac compression can support adequate blood flow for hemodialysis. We report a case of a 68-year-old woman who developed sudden cardiac arrest secondary to hyperkalemia with renal insufficiency. Despite 100 minutes of cardiopulmonary resuscitation and conventional treatment for hyperkalemia, the cardiac arrest still persisted. Hemodialysis was then initiated during cardiopulmonary resuscitation and the patient restored spontaneous heart beat 20 minutes later. There was no neurologic sequela after her recovery. Hemodialysis should be considered early in the course of cardiopulmonary resuscitation in severe hyperkalemia induced cardiac arrest if conventional therapies were judged to be ineffective.

Aged↗
PubMed1999

Evaluation of transdermal iontophoresis of enoxacin from polymer formulations: in vitro skin permeation and in vivo microdialysis using Wistar rat as an animal model.

Polymers were used in vehicles to form hydrogel matrices in this study to evaluate the in vitro permeation and in vivo microdialysis of enoxacin. The highest transdermal delivery determined by area under flux-time curve (AUC) and intracutaneous enoxacin concentration were observed in methylcellulose (MC) and polyvinylpyrrolidone (PVP) hydrogels, respectively. To avoid the pH shift in vehicles during iontophoresis, buffer species were added to formulations to increase the buffer capacity. As expected, the permeability of enoxacin of anodal iontophoresis was larger than that of cathodal iontophoresis. Combination of benzalkonium chloride, a cationic surfactant as an enhancer, and iontophoresis exerted an enhancing effect for anionic enoxacin at pH 10.0. However, no effect or a negative effect was detected for cationic enoxacin in deionized water or pH 5.0 buffer, due to the shielding of the negative charge in the skin. The skin residue of enoxacin was slightly increased after the incorporation of Azone in PVP hydrogel. The result of in vivo microdialysis was in accordance with that of in vitro study. The effect of Azone on the intracutaneous enoxacin was more significant for in vivo microdialysis than in the in vitro study indicating the clinical feasibility of Azone for iontophoretic delivery. Microdialysis can be considered as a useful technique to investigate the pharmacokinetics of transdermal iontophoresis in vivo.

Administration, Cutaneous↗
PubMed1999

Spontaneous variability of arterial oxygenation in critically ill mechanically ventilated patients.

OBJECTIVE: To assess the magnitude of spontaneous variability of arterial oxygenation and oxygen tension-based indices over time in medical intensive care unit (ICU) patients and to study whether high positive end-expiratory pressure (PEEP) or inverse inspiratory-to-expiratory (I:E) ratio ventilation (IRV) results in a greater variability than low PEEP with conventional I:E ratio ventilation. DESIGN: Prospective study. SETTING: Medical ICU in a tertiary medical center. PARTICIPANTS: 23 patients requiring a pulmonary artery floating catheter for hemodynamic monitoring. INTERVENTION: After being completely sedated, patients were randomized to receive pressure-control ventilation at setting A: high PEEP (15 cm H2O) with conventional I:E ratio (1:2) and setting B: inverse I:E ratio (2:1) with low PEEP (5 cm H2O) alternately, and then at setting C: low PEEP (5 cm H2O) with conventional I:E ratio (1:2). Each ventilation setting lasted 1 h. MEASUREMENTS AND RESULTS: The arterial and mixed venous blood samples were measured simultaneously at baseline (time 0), and at 15, 30, 45, and 60 min thereafter. The coefficient of variation (CV) of arterial oxygen tension (PaO2) over time was 5.9 % for setting A, 7.2 % for setting B, and 6.9 % for setting C. ANOVA showed no significant differences in CVs of PaO2 between the three settings. Oxygen tension-based indices, alveolar-arterial oxygen difference (A-aDO2) and PaO2/ PAO2 (alveolar oxygen tension), displayed CVs equal to that of PaO2; the CV of A-aDO2/PaO2 was significantly greater than that of PaO2. CONCLUSIONS: In critically ill medical ICU patients, despite sedation, the spontaneous variability in PaO2 over time is substantial. A high PEEP or IRV does not contribute to the increased variation in PaO2.

APACHE↗