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Biomedical subjects

T K Wong

Publications and source records attributed to T K Wong.

At least 19 recordsLinked to original sources
PubMed1992

Improved method for the isolation and cultivation of human scalp dermal papilla cells.

We present an improved method for the isolation and cultivation of human scalp anagen hair follicle dermal papilla cells. Following treatment of the isolated dermal papilla with collagenase, incubation in Chang's medium mediates accelerated growth of the papilla cells when compared with other media such as DMEM, M199, and EMEM. Upon reaching confluency, the cells cultured in this fashion exhibit a multilayer-forming property that is dependent on normal proteoglycan synthesis. The papilla cells maintain this morphologic behavior for as long as 7 weeks in culture, or after being subcultured six times. During this time, the cells continue to synthesize extracellular matrix components associated with the human anagen follicle in situ. These include chondroitin sulfate, laminin, and type IV collagen. Type III collagen and keratan sulfate are poorly expressed by the papilla both in situ and in vitro. Heparan sulfate proteoglycan, a matrix component of the papilla in situ, is poorly expressed in vitro. Earlier reports suggested that the expression of extracellular matrix components is not maintained in culture. We show that the expression of these molecules is not dependent on the secondary culture medium, but continues in DMEM and M199 after primary culture in Chang's medium. Our results suggest that initial exposure of the dermal papilla to Chang's medium either selectively permits the outgrowth of papilla cells having extracellular matrix components similar to those found in situ, or stabilizes the expression of extracellular matrix components among the entire cultured cell population.

Cell Division↗
PubMed1992

Endotracheal lidocaine instillation in pediatric anesthesia.

The purpose of this study is to evaluate the effectiveness of lidocaine administered via the endotracheal tube in suppressing cough reflex during anesthetic recovery in children. Fifty ASA class I-II children, aged from 1-5 years old undergoing elective abdominal or urogenital surgery were randomly assigned into two groups. 2% lidocaine 1.5 mg/kg (1ml = 20mg) was administered in group B while normal saline (N/S) 0.1 ml/kg was used in group A (control group). Either one of the agents was instilled into the endotracheal tube right before the end of operation. Airway responses and other associated phenomena were recorded during the recovery period. Recovery condition was categorized into a two-grade categories, namely "good", and "poor" to denote the quality of recovery. Recovery conditions differ significantly between the control group and the experimental group. In group A, 3 patients were classified as the "good" grade but 22 patients were categorized in the "poor" grade. Group B (lidocaine 1.5 mg/kg) has a much better recovery condition than the control group, there were 19 in the "good" grade and only 6 in the "poor" grade. The experimental group treated with 2% lidocaine presented a significantly better recovery than the control group. This effective suppression of the cough reflex might be due to the local anesthetic effect exerted by lidocaine. For the sake of safety all patients were closely followed up at the post anesthesia room until the return of consciousness and laryngeal reflexes. In conclusion, we found that 2% lidocaine 1.5 mg/kg given intratracheally via the endotracheal tube could attenuate cough response during recovery in pediatric anesthesia.

Abdomen↗
PubMed1992

Comparison of methods for measuring free thyroxin in nonthyroidal illness.

Patients with severe nonthyroidal illness (NTI) often have decreased serum thyroxin (T4) concentrations and sometimes have decreased free T4 (FT4) and increased tumor necrosis factor-alpha (TNF-alpha) concentrations. We evaluated four commercial methods for measuring FT4 [Abbott IMx, Amersham Amerlex MAB, Nichols, and Diagnostic Products Corporation (DPC) RIA] and one method for TNF-alpha in 41 NTI patients, 24 euthyroid control subjects, and 10 hypothyroid patients. Free T4 index (FTI) was also measured by the Abbott IMx method. Euthyroid subjects results were in the stated normal ranges. NTI FT4 was subnormal in 2.4%, 61%, and 29% by the Nichols, DPC, and Amerlex methods, respectively. The DPC, Amersham Amerlex, and Abbott IMx methods gave significantly lower FT4 values for the NTI group than for the controls. There were good correlations between the various FT4 methods in the NTI group. FTI concentrations correlated well with FT4 for the euthyroid and hypothyroid groups but poorly for the NTI group. The Abbott IMx and Nichols RIA methods yield values in the hypothyroid range for only a small proportion of NTI patients.

Adult↗
PubMed1991

Comparison of inguinal nerve block and intravenous fentanyl in relieving postinguinal herniorrhaphy pain for pediatric outpatients.

The purpose of this study was to compare the effects of ilioinguinal/iliohypogastric (IG/IH) nerve block and intravenous fentanyl for pain control following inguinal herniorrhaphy in pediatric outpatients. Seventy-five ASA physical status I and II children (aged 1 to 10 yr) with unilateral inguinal herniorrhaphy under general anesthesia were randomly divided into three groups. Group A received IG/IH nerve block, using 0.25% bupivacaine (1 mg/kg) immediately after induction. Group B received intravenous fentanyl (1 microgram/kg) immediately after induction. Group C received only general anesthesia as control. At postanesthetic care unit (PACU), we recorded the degree of pain/or discomfort at 5, 15, 30, 45 and 60 min using modified Hannallah's scoring system after the patient was fully awake. The degree of recovery was also evaluated using Steward's scoring system. After discharge, the parents were interrogated about the condition of child within 24 h by telephone. Follow-up items raised included vomiting, drowsiness, pain and shivering. Our results showed that children in both study groups had lower pain score than those in the control group, and in the fentanyl group children had lower pain score than in the nerve block group during the first 30 min at PACU. The recovery time was also longer in the fentanyl group. There was no significant difference among the three groups regarding the raised items over telephone interrogation. In sum, inguinal nerve block was effective for postoperative pain relief in children undergoing inguinal herniorraphy. We also suggested that small dose of intravenous fentanyl would serve as an easy, simple and effective means for relieving postinguinal herniorrhaphy pain during the first 30 min of the initial postoperative period.

Child, Preschool↗
PubMed1990

Drug calculations for nurses--a computer assisted learning application.

A summative evaluation of the effectiveness of a computer assisted learning package, 'Drug Calculations for Nurses' was conducted. Two groups of students, the experimental and control were chosen from the schools of nursing where English was used as the medium of instruction. The experimental group was taught drug calculations in classrooms, but not the control group. Both groups used the software after they had attempted a drug calculation test. A post-treatment test of similar nature was undertaken to reflect the students' mathematical achievement. An attitude semantic differential was used to measure subjects' attitude. Findings of this investigation indicated that there was a significant difference in mathematical achievement of the students who experienced both teaching strategies as compared with the group taught by the computer software only. The experimental group scored significantly higher in their post-treatment test. Even though the control group did show some improvement, it was not statistically significant. Both groups demonstrated a positive attitude towards computer assisted learning, however, only the mean scores for the subscales comfort and function were significant. Implications of this study were then identified and areas for future research were recommended.

Attitude of Health Personnel↗
PubMed1990

Placental markers of human exposure to polychlorinated dibenzofurans and polychlorinated biphenyls: implications for risk assessment.

In 1979, rice oil accidentally contaminated with a mixture of polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) was ingested by a large number of individuals in Taiwan. Placentas obtained from women four years after the exposure had occurred contained several PCB congeners known to be present in the rice oil as well as two toxic PCDF congeners: 2,3,4,7,8-pentachlorodibenzofuran (2,3,4,7,8-PCDF) and 1,2,3,4,7,8-hexachlorodibenzofuran (1,2,3,4,7,8-HCDF). Placentas from exposed women had markedly elevated activities of two cytochrome P1-450 dependent enzymes, arylhydrocarbon hydroxylase and ethoxyresorufin O-deethylase. The average magnitude of enzyme induction was 100-fold, but much interindividual variation was evident. Binding properties of epidermal growth factor (EGF) to its receptor were not altered by PCB-PCDF exposure. However, EGF-stimulated autophosphorylation of the EGF receptor was decreased significantly in placentas from exposed women and this effect was strongly correlated with decreased birth weight. Species comparisons of effects on EGF receptor actions and cytochrome P-450 isoenzymes, coupled with data on tissue concentrations of PCDFs, suggest that humans are more sensitive than rats to some of the biochemical effects of PCDFs and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The data are discussed in relation to key issues in the risk assessment of the toxic halogenated aromatics.

Animals↗
PubMed1990

Low concentration of caudal bupivacaine for postoperative analgesia in elective pediatric surgery.

This report summarizes [corrected] our experiences in 0.125% bupivacaine caudal analgesia in 70 pediatric patients with age ranging from 3 months to 7 years undergoing routine surgical procedures including herniorrhaphies, orchiopexies, and circumcision. The local anesthetic chosen was 0.125% bupivacaine with epinephrine (1:200,000) being added and the dosage administered [corrected] varied from 0.5-1.0 ml/kg depending upon the sites of the surgical procedures. In the recovery room, patients were observed and accessed using the modified Hannallah's pain/discomfort scoring system. Patients who achieved a score of four or more during a 30 min observation period were given codeine 1 mg/kg intramuscularly and the blocks were rated as uneffective. Our result was that 0.125% bupivacaine caudal analgesia was effective. The rate of success was 79%. The duration of analgesia was 4-8 hours. No delay or difficulty in urination was found. Most of the patients could move their lower extremities but could not bear their weight. Telephone follow-up failed to reveal any analgesia-related complication.

Analgesia, Epidural↗
PubMed1989

The conformation of dolichol.

An understanding of the natural conformation of dolichol is important for the elucidation of the mechanism of protein glycosylation and dolichol's other as yet undisclosed biological functions. Since the molecular mechanics method has been shown to be well suited for the prediction of alcohol and alkene conformations, we have employed it to study the conformations of apparent least energy of dolichol-19 and smaller polymers of isoprene, namely, squalene, trans,trans-farnesol, and cis,cis-farnesol. Additionally, the small-angle X-ray scattering (SAXS) method was employed to determine the validity of the apparent least energy conformer of dolichol-19 derived by the molecular mechanics method. The results indicate that the solution conformation of dolichol-19 is comprised of a central coiled region flanked by two arms. The central coiled region has two and a half turns of dimensions 9.84 x 16.55 x 51.66 A3. The arms of dimensions 3.99 x 5.89 x 17.47 A3 and 4.49 x 9.23 x 11.14 A3 are approximately diametrically opposed. Measurement of the intrinsic viscosity of dolichol in both isopentyl alcohol and oleyl alcohol showed that the natural conformation of dolichol is capable of increasing solution fluidity (i.e., lowering solution viscosity). Thus, while examination of the conformation of dolichol in a membrane-mimetic solvent by SAXS is not possible, the quantitative measure of the effect of dolichol on solution viscosity (and thus solution fluidity) is possible. The results are consistent with dolichol acting as a membrane-fluidizing agent and provide the first quantitative measure of the effect of dolichol on solution fluidity of a membrane-mimetic solvent.

Dolichols↗
PubMed1989

Hybrid acute leukaemia--a report of 3 cases.

The simultaneous expression of both lymphoid and myeloid phenotypic features in acute leukaemia is rare. We report 3 cases of biphenotypic hybrid acute leukaemia seen in our institution. All 3 patients achieved remission with treatment for acute lymphoblastic leukaemia but two subsequently relapsed while on treatment. The hybrid acute leukaemias are important areas for further research both for delineation of basic biology and choice of optimal treatment.

Child↗
PubMed1987

Dose requirements, assay procedures and tissue specificity for PCB inductation of P-450 dependent mono-oxygenase activity in the rat: implications for design of studies measuring in vivo induction of human placental mono-oxygenases.

Pregnant Sprague-Dawley and Fisher 344 rats were treated on day 15 of gestation with Aroclor 1254 in a single dose ranging from 0 to 500 mg kg-1 body weight and killed on day 18 of gestation. In the small groups of animals used for this study, no effect was observed on mean maternal liver or placental weight, or the number of fetal resorptions at any of the doses tested. Measurement of aryl hydrocarbon hydroxylase (AHH) and 7-ethoxycoumarin O-deethylase (7ECD) activity in tissue homogenates, however, showed that administration of Aroclor 1254 (15 mg kg-1 body weight or greater) induced mono-oxygenase activity in fetal liver. Both the AHH and 7ECD assay detected effects of PCBs with similar sensitivity, and the findings were comparable when homogenates were assayed instead of microsomes. These data were used to suggest technical approaches to the detection of mono-oxygenase induction in placental tissue human populations exposed to PCBs.

Animals↗
PubMed1987

Placental markers of human exposure to polychlorinated biphenyls and polychlorinated dibenzofurans.

Our studies have evaluated biochemical changes in placentae from humans exposed to rice oil contaminated with polychlorinated biphenyls (PCBs) and polychlorinated dibenzofurans (PCDFs) in Taiwan. Placentae were obtained from nonsmoking women 4 to 5 years after the exposure had occurred. The exposed individuals ingested approximately 1 to 3 g PCBs and 5 mg PCDFs, and many exhibited symptoms characteristic of PCB poisoning. This disease was termed "Yu-Cheng" in Chinese. Based on data from experimental animal models, we examined a number of parameters in placentae from control and exposed women, including arylhydrocarbon hydroxylase (AHH) activity, cytochrome P-450 isozymes, epidermal growth factor (EGF) receptor binding properties and actions, and Ah receptor. We also quantified concentrations of various PCB and PCDF congeners known to be present in the contaminated rice oil. Our results revealed a dramatic elevation in placental AHH activity in samples from PCB/PCDF-exposed women. This increase in enzyme activity was associated with a parallel increase in placental microsomal protein immunochemically related to cytochrome P-450 form 6 [derived from 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced rabbit lung]. No other cytochrome P-450 isozyme was detected in placental preparations, and the form 6 homolog was found only in placentae from exposed women. EGF receptor-mediated autophosphorylation capacity was significantly diminished in PCB/PCDF placentae, but this effect was not associated with changes in plasma membrane EGF receptor binding properties (Kd and Bmax). The EGF receptor autophosphorylation effect correlated well with the decrease in birthweight observed in offspring of exposed women, suggesting that this biochemical event might provide a good marker of effect for the toxic halogenated aromatics.

Adolescent↗
PubMed1987

Administration-time-dependency of the pharmacokinetic behavior and therapeutic effect of a once-a-day theophylline in asthmatic children.

Using a double-blind, placebo-control, crossover study design, 8 asthmatic children (8-15 years) were evaluated for temporal patterns in airways function throughout separate study periods when treatment was placebo or Theo-24 once-daily on separate occasions at 0600, 1500 or 2100 hr. During 39-hr in-hospital observations, pulmonary function and serum theophylline concentrations (STC) were assessed every 3 hr under all treatments. The pharmacokinetics of Theo-24 varied greatly depending on the dosing time. For the afternoon and evening dosings, the Cmax, Tmax, AUC, % swing, % fluctuation, % AUC fluctuation, % nocturnal excess and Cav(2-6 hr) were all statistically significantly greater than for the morning dosing. Compared with the placebo regimen, dosing patients with Theo-24 at 1500 hr disrupted circadian patterns of airways function, especially airways patency, while dosing at 2100 hr, reduced the amplitude and shifted the acrophase of several spirometric measures to a slightly earlier time. Theo-24 treatment irrespective of dosing time resulted in comparable enhancement of the group 24-hr mean, minimum and maximum values of airways patency with reference to placebo baselines. Theo-24 dosing at 1500 or 2100 hr, however, resulted in the best effect on the airways as assessed by the 24-hr mean FEV 1.0 level in 7 of the 8 asthmatic children. When the drug was given at 1500 hr, the time of lowest FEV 1.0 was shifted from the nighttime hours in 5 of 8 patients. These findings suggest that clinicians need to individualize the theophylline dosing schedule of patients to best control the symptoms of asthma.

Asthma↗
PubMed1987

Decreased human birth weights after in utero exposure to PCBs and PCDFs are associated with decreased placental EGF-stimulated receptor autophosphorylation capacity.

Yucheng (oil disease) is a clinical and metabolic syndrome reported in Taiwanese who consumed rice oil contaminated with large amounts of various polychlorinated biphenyls (PCBs) and polychlorinated dibenzofurans (PCDFs), including the 2,3,4,7,8- and 1,2,3,4,7,8-PCDF congeners which are similar in structure and toxicity to 2,3,7,8-tetrachlorodibenzo-p-dioxin. A well known characteristic of Yucheng is the marked decrease in birth weights, although the underlying mechanism of this effect is unclear. Placental epidermal growth factor (EGF) receptor binding and autophosphorylation studies were done using tissue samples taken from Yucheng and unexposed control patients. EGF-stimulated receptor autophosphorylation of the human placental EGF receptor in the Yucheng subjects was decreased more than 60% of control levels, 4-5 years after the exposure had occurred. The decrease in EGF receptor phosphorylation was significantly correlated with decrease in birth weights. Nonlinear regression analysis of the 125I-EGF receptor binding data revealed that there were two distinct EGF receptor binding isotherms representing the high affinity-low capacity (HALC) and the low affinity-high capacity (LAHC) binding sites. In contrast to the placental EGF-stimulated phosphorylation data described above, the binding kinetics of the EGF receptor were not significantly altered in the control [HALC site Kd = 0.10 +/- 0.02 (SE) nM, Bmax = 788 +/- 255 fmol/mg of protein; LAHC site Kd = 17.4 +/- 8.2 nM, Bmax = 62 +/- 32 pmol/mg) compared to the Yucheng subjects (HALC site Kd = 0.11 +/- 0.02 nM, Bmax = 784 +/- 305 fmol/mg; LAHC site Kd = 49.5 +/- 24.7 nM, Bmax = 147 +/- 80 pmol/mg). GC-MS analysis of placental specimens showed elevated levels of selected PCB and PCDF congeners in the Yucheng compared to control individuals. Total PCB levels were 0.5 +/- 0.2 ppb and 20.0 +/- 4.8 ppb for the control and Yucheng subjects, respectively. A significant dose-response relationship was observed between the placental EGF receptor phosphorylation levels and the PCB concentrations (total or concentrations of 2,2',4,4',5,5'-hexa- and 2,2'3,3'4,4',5-heptachlorobiphenyls). In contrast, no significant relationship was found between the EGF receptor phosphorylation activity and the 2,3,4,7,8- or 1,2,3,4,7,8-PCDF congeners, which were at nondetectable levels in the control and between 104 and 374 parts per trillion in the Yucheng subjects. In summary, our data reveal that decreased placental EGF receptor phosphorylation capacity is associated with decreased birth weight. Furthermore, PCB tissue concentrations might be a better predictor of effects than are PCDF concentrations.

Benzofurans↗
PubMed1986

Nondetectable concentrations of human placental Ah receptors are associated with potent induction of microsomal benzo[a]pyrene hydroxylase in individuals exposed to polychlorinated biphenyls, quaterphenyls, and dibenzofurans.

Human exposure to polychlorinated biphenyls, quaterphenyls, and dibenzofurans occurred in an accidental food poisoning episode in Taiwan in 1979. Our objective was to evaluate the role of Ah receptors in the production of biochemical effects detected in placentas from exposed subjects. Placentas were obtained from pregnant women who were identified from a registry of exposed individuals. Benzo[a]pyrene (BaP) hydroxylase was quantified in placental microsomes and Ah receptor was investigated in placental cytosolic and nuclear fractions by a variety of receptor-binding techniques using 2,3,7,8-[1,6-3H]tetrachlorodibenzo-p-dioxin ([3H]TCDD) as the ligand. Microsomal BaP hydroxylase was dramatically elevated in placentas of exposed subjects compared to those of nonexposed, nonsmoking control subjects. However, concentrations of displaceable [3H]TCDD binding in placental preparations from exposed or control subjects were uniformally low; approximately 1.0 fmol/mg cytosolic protein. Further evaluation of displaceable TCDD binding by sucrose-gradient sedimentation and hydroxylapatite column chromatography revealed that binding properties were different than those for the Ah receptor. These data suggest that extremely low concentrations of Ah receptors in human placenta may be sufficient to markedly elevate microsomal BaP hydroxylation. Alternatively, induction in human placenta may be mediated by a mechanism not requiring Ah receptor.

Adolescent↗
PubMed1986

DNA-repair studies with sodium fluoride: comparative evaluation using density gradient ultracentrifugation and autoradiography.

Sodium fluoride (NaF) was assayed for the induction of DNA-repair synthesis in WI-38 human diploid fibroblasts and in primary cultures of rat hepatocytes. DNA-repair synthesis in non-replicating DNA was measured by ultracentrifugation of density-labeled DNA in CsCl gradients. When this method was used, NaF did not induce DNA-repair synthesis in either of these cell types. However, when NaF was assayed for induction of unscheduled DNA synthesis (UDS) in rat hepatocytes by autoradiography, an increased net nuclear grain count was observed. Because the autoradiographic results were not confirmed by density-gradient ultracentrifugation of hepatocyte DNA, which is a more definitive technique, it is doubtful whether the autoradiographic results actually represent DNA-repair synthesis. Modifications of the UDS/autoradiography protocol to include more extensive washing resulted in no UDS response. Published reports (Hellung-Larsen and Klenow, 1969; Srivastava et al., 1981) describe the formation of precipitable complexes of Mg2+, F-, and [3H]thymidine triphosphate which suggests that autoradiographic measurement of UDS may lead to artifacts when testing NaF unless extensive washing of the cultures is employed.

Animals↗
PubMed1986

Correlation of placental microsomal activities with protein detected by antibodies to rabbit cytochrome P-450 isozyme 6 in preparations from humans exposed to polychlorinated biphenyls, quaterphenyls, and dibenzofurans.

Placental tissues were obtained from Chinese women in Taiwan who had been exposed to contaminated rice oils containing polychlorinated biphenyls and their thermal degradative products. Exposure via the diet occurred 4-5 years prior to pregnancy. Placental microsomal fractions from eight of the nine exposed subjects studied showed marked elevation of benzo(a)pyrene hydroxylation and 7-ethoxyresorufin O-deethylation activities related to control subjects. Placental microsomes from exposed subjects were found to contain a protein that cross-reacted with antibodies raised to rabbit cytochrome P-450 isozyme 6, an isozyme induced by polycyclic aromatic hydrocarbons. This protein was not observed with microsomal samples from control subjects. A significant correlation was found between the relative amounts of the immunoreactive protein and benzo(a)-pyrene hydroxylation and 7-ethoxyresorufin O-deethylation activities. The 7-ethoxyresorufin O-deethylation activities were inhibited by alpha-naphthoflavone, a compound known to inhibit activities of rabbit cytochrome P-450, isozyme 6.

Benzo(a)pyrene↗