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Biomedical subjects

R S Wu

Publications and source records attributed to R S Wu.

At least 37 records · Page 2Linked to original sources
PubMed1999

Telomere-interactive agents affect proliferation rates and induce chromosomal destabilization in sea urchin embryos.

Cationic porphyrins, which interact with guanine quadruplex (G4) telomeric folds, inhibit telomerase activity in human tumor cells. In this study, we have further examined effects of porphyrins and other telomere- and telomerase-interactive agents on proliferation rates and chromosome stability in a novel in vivo model, developing sea urchin embryos. We studied two porphyrins: (i) TMPyP4, a potent telomerase inhibitor; and (ii) TMPyP2, an isomer of TMPyP4 and an inefficient telomerase inhibitor, azidothymine (AZT), the reverse transcriptase inhibitor, antisense phosphorothioate oligonucleotide to telomerase RNA (TAG6) and a control scrambled sequence (ODN). TMPyP4, AZT and TAG6 (but not TMPyP2 or ODN) decreased the rates of cell proliferation and increased the percentage of cells trapped in mitosis. Nuclear localization of TAG6, but not of ODN, was demonstrated with 5'-fluoresceinated analogs of TAG6 and ODN. Formation of elongated chromosomes incapable of separating in anaphase, induced by TMPyP4, AZT and TAG6, closely resembled phenotypes resulting from telomerase template mutation or dominant negative TRF2 allele. Our data suggest that G4-interactive agents exert their antiproliferative effects via chromosomal destabilization and warrant their further development as valuable anticancer tools.

Animals↗
PubMed1998

Fate and risk evaluation of persistent organic contaminants and related compounds in Victoria Harbour, Hong Kong.

The Environment Protection Department of Hong Kong has a monitoring program for persistent organic contaminants in sediments of Victoria Harbour, the main harbour of Hong Kong. A fugacity model has been used, based on this sedimentary data, to estimate inputs to the system (probably from sewage, stormwater and industrial discharges) as well as the fate of the contaminants, particularly in terms of the aqueous and biotic concentrations. The risk of deleterious effects on the natural marine system, as well as on the consumers of seafood from the system, was carried out using the estimated aqueous and biotic concentrations together with accepted environmental quality guidelines. The result of our analysis indicated that the chlorohydrocarbons, PCBs (as Aroclor 1254) total DDT and total HCH pose a significant risk, and probably have caused damage to the marine ecosystem as well as posing a hazard to seafood consumers. Much higher concentrations of the less toxic total alkanes, nonaromatic hydrocarbons, linear alkyl benzenes and the compounds giving a unresolved complex mixture (UCM) cannot be evaluated due to a lack of environmental guidelines and the complexity of these substances. However, it is probable that these substances add adverse effects to those due to the other contaminants.

Benzo(a)pyrene↗
PubMed1998

Recolonization and succession of marine macrobenthos in organic-enriched sediment deposited from fish farms.

High organic loading deposited on the sea bottom by marine fish farming activities often eliminates benthic organisms in the vicinity. In this study, organic-enriched sediment collected underneath a fish farm was defaunated, placed in settling trays and exposed to the subtidal area of a clean site of similar hydrography. Trays were sampled monthly for a consecutive period of 5 months, and recolonization and successional patterns of macrobenthos were studied using univariate and multivariate statistics. Recolonization occurred rapidly, and averages of 144 animals/tray and 26 species/tray were recorded within the first month. Molluscs accounted for 49% of species and polychaetes for 77% of abundance during the first month of recolonization. Temporal changes in abundance, diversity and species composition found in subsequent months resembled spatial changes of benthic community along a decreasing pollution gradient generalised by Pearson and Rosenberg (1978, Oceanography & Marine Biology Annual Review 16, 229-311). Abundance reached a peak after 3 months (434 animals/tray) and then declined. Species number also increased, peaked after 4 months (47 species/tray), and was followed by a decrease. The polychaete Prionospio malmgreni succeeded Pseudopolydora paucibranchiata as the dominant species after the first month, reached a peak (194 animals/tray) after 3 months, then declined sharply. The rapid recolonization and succession of the macrobenthic community on organic-enriched sediment suggested that present fish farming methods are unlikely to have a long-term impact on benthic communities once farming activities are reduced/ceased.

Journal Article↗
PubMed1998

Alternation of one-lung and two-lung ventilations with the same single-lumen endobronchial tube during thoracoscopic surgery--a case report.

One-lung ventilation is sometimes necessary for procedures performed through thoracotomy. Single lumen endobronchial tube has been used purposefully for one lung ventilation since 1931. However, there are no reports on intra-operative alternation of one-lung and two-lung ventilations through the same single lumen endobronchial tube as it can only provide unilateral lung ventilation. We present a case in whom a tube exchanger was used to readjust tube position so as to provide alternation of one-lung and two-lung ventilations in a thoracoscopic procedure.

Anesthesia, General↗
PubMed1997

Epimerization studies of LSD using 1H nuclear magnetic resonance (NMR) spectroscopy.

A study was conducted to determine the conditions needed to achieve the equilibrium concentration for the epimerization of d-lysergic acid diethylamide (LSD) to iso-LSD. The reaction was followed by integration of the C-9 resonance of LSD and iso-LSD by proton nuclear magnetic resonance (NMR). The C-9 resonance of LSD and iso-LSD appear as singlets at 6.35 and 6.27 ppm respectively. Starting with pure LSD, the conversion to iso-LSD is attained at temperatures above 37 degrees C and pH levels over 7.0. At a pH of 7.0 or higher, the LSD/iso-LSD ratio of 9:1 is achieved after one week at 45 degrees C or two weeks at 37 degrees C. Starting with iso-LSD, the conversion to LSD requires more vigorous conditions. The 9:1 LSD/iso-LSD ratio is attained only after 6 weeks at a temperature of 45 degrees C and a pH of 9.7. At lower pH levels, the reaction proceeds more slowly. The 9:1 LSD/iso-LSD ratio is achieved whether the starting material is LSD or iso-LSD and therefore represents an equilibrium concentration (K = 9). In addition, the more vigorous conditions needed to achieve equilibrium of iso-LSD to LSD demonstrate the difficulty in extraction of the epimerizable proton of iso-LSD. This study is the first to quantitate the epimerization of LSD by NMR techniques and establishes the conditions needed to induce epimerization in solution.

Drug Stability↗
PubMed1997

[Protective effect of schisanhenol (SAL) on oxygen free radical induced injury of spleen lymphocytes in mice].

In the present paper the effects of Sal, an active component isolated from Kadsura Longipenduculata Finet et Gagnep, on oxygen free radical induced injury of murine spleen lymphocytes in vitro and in vivo were investigated. The results showed that Sal at 1 x 10(-4) mol.L-1 significantly inhibited the decrease of GSH content induced by Fe(2+)-Vit C and the increase of MDA formation induced by Fe(2+)-Cys in murine spleen lymphocytes. The decrease of membrane fluidity of lymphocytes under lipid peroxidation induced by Fe(2+)-Vit C was prevented by Sal. The damage of the lymphocyte surfaces induced by Fe(2+)-Vit C was also markedly reduced by Sal. Administration of Sal 20 mg.kg-1.d-1 for 8 d significantly increased the GSH content of the spleen lymphocytes in mice under high oxygen-stress. Meanwhile, the compensative increase of SOD activity in the spleen lymphocytes was reversed. The results suggest that Sal may protect murine spleen lymphocytes from the injury induced by oxygen free radicals.

Animals↗
PubMed1997

Endotracheal tube size selection guidelines for Chinese children: prospective study of 533 cases.

Appropriate selection of the size of an endotracheal tube (ETT) for use in children is important both in general anesthesia and critical care practice. Past published data on guidelines for selecting ETT size in children are based on Caucasian measurements. As body build is generally different in Chinese children compared with Caucasians of the same age group, guidelines for Chinese children are needed. The aim of this study was to determine guidelines for ETT size selection by recording and comparing age, body weight, length, head girth and circumference of the right fifth finger of the child. Correlations between internal diameter (ID) of the chosen ETT and the child's data were calculated and compared. In this study, 533 Chinese children. American Society of Anesthesiolgists class I or II, aged from 3 months to 6 years, undergoing oral intubation for general anesthesia for minor pediatric surgery were enrolled. Our results showed that body length (height) had the best correlation to the size of an uncuffed oral ETT. Through stepwise regression, a formula. ETT ID = 2 + (body length (cm)/30), was obtained.

Asian People↗
PubMed1997

Dislodgment of catheter during arterial cannulation: a case report.

Invasive blood pressure monitoring is important in medical practice, especially for hemodynamic monitoring of the critically ill. Catheter dislodgment is a rarely reported complication. We herein report a catheter dislodgment complication during the procedure of arterial cannulation.

Catheterization, Peripheral↗
PubMed1997

Evoked facial nerve EMG and brainstem auditory evoked potential monitoring in cerebellopontine angle tumor resection.

BACKGROUND: The preservation of normal nerve function or identification of nerve route is critical in some surgeries of cerebellopontine angle tumors. Over the last 5 years, intraoperative facial nerve electromyogram (EMG) and brainstem auditory evoked potential (BAEP) were applied for evaluation of facial nerve integrity and brainstem function in patients while undergoing resection of cerebellopontine angle (CPA) tumor. This report represents the retrospective analysis of our results. METHODS: The inhalational anesthesia with 1-1.5% isoflurane in pure O2 was used. Muscle relaxation was maintained with continuous infusion of atracurium. The degree of muscle relaxation was aimed at a T4/T1 ratio of train-of-four response more than 20% of the adductus pollicis upon ulnar nerve stimulation at the wrist. In 236 patients suffering from CPA tumor without facial palsy, the EMG of the mentalis muscle ipisilateral to the tumor was obtained through stimulation of the facial nerve. The stimulation was applied with a nerve finder, which delivered an electrical stimulation of a single 2 mamp direct current. The EMG finding was compared with the clinical result. In 198 patients, BAEP was used to monitor the brainstem function during tumor resection. In case of intact hearing the BAEP was taken ipsilateral to the operation side and in case with total hearing loss contralateral BAEP to operation side was used. For BAEP stimulation, 90 db click sound stimulation with frequency of 11.26 Hz was applied to both ears. BAEP signals were obtained and recorded at the mastoid region of either side in reference to the vertex. The EMG and BAEP signals were recorded and saved to an evoked potential monitor. RESULTS: In facial nerve EMG monitoring, there were two false positive and no false negative tests. Except for the two false positive tests, the postoperative clinical results in the other cases were compatible with the intraoperative facial nerve EMG findings. In BAEP monitoring, there were twenty-eight positive tests. CONCLUSIONS: The low incidence of false negative test suggests that facial nerve EMG is valuable in detection of facial nerve function in CPA tumor resection. Intraoperative BAEP abnormality is possibly useful in identifying postoperative brainstem dysfunction.

Adult↗
PubMed1997

Unexpected left endobronchial intubation in a case of Turner's syndrome.

Patients with Turner's syndrome present a multiplicity of cardiovascular and airway abnormalities. We describe a case of Turner's syndrome with pericardial effusion who experienced an inadvertent endobronchial intubation due to displacement of the endotracheal tube immediately after the pericardial drainage. A sudden increase of airway pressure and decrease of oxygen saturation in the presence of breathing sound audible via the chest piece placed on the left hemithorax first misled us to call our attention to sputum impaction. No sputum was obtainable from airway suction. Inadvertent bronchial intubation was highly suspected at the post-anesthesia room when a decrease of right side breathing sound was noted together with a progressive fall of oxygen saturation. Emergent chest x-ray confirmed the diagnosis. It was thought that the mishap took place early in the act of or following the pericardial drainage. Our case serves as evidence once again to emphasize the possibility of endobronchial intubation due to displacement of endotracheal tube during anesthesia and the importance of monitoring to guard against inadvertent bronchial intubation, particularly in patients with associated problems such as Turner's syndrome with huge pericardial effusion.

Adult↗
PubMed1996

Comparative effects of thiopentone and propofol on respiratory resistance after tracheal intubation.

To compare the effects of propofol and thiopentone on tracheal intubation-induced bronchoconstriction, 37 patients were allocated randomly to anaesthesia with either thiopentone 4 mg kg-1 followed by a 15-mg kg-1 h-1 continuous infusion or propofol 3 mg kg-1 followed by a 9-mg kg-1 h-1 continuous infusion. Intubation was facilitated by vecuronium 0.1-0.2 mg kg-1. Respiratory system resistance (Rrs) was measured by a CP-100 pulmonary function monitor, 5 min after intubation. The 5-min post-intubation Rrs values were significantly lower in the propofol group (8.5 (SD 1.5) cm H2O litre-1 S-1) than in the thiopentone group (10.9 (3.2) cm H2O litre-1 S-1). Thirty minutes after commencing isoflurane-nitrous oxide anaesthesia, Rrs declined by 17.5 (SEM 3.6)% from baseline in the thiopentone group, but by only 1.6 (2.6)% in the propofol group. We conclude that the dose of propofol administered provided more protection against tracheal intubation-induced bronchoconstriction than an induction dose of thiopentone.

Adult↗
PubMed1996

Isoflurane anesthesia does not add to the bronchodilating effect of a beta 2-adrenergic agonist after tracheal intubation.

This double-blind study investigates whether isoflurane/N2O anesthesia adds to the bronchodilating effect of the beta 2-adrenergic agonist, fenoterol, after an endotracheal tube (ETT)-induced increase in airway resistance. Forty-five patients with ASA physical status I-II were randomly assigned to two groups: fenoterol-treated patients (n = 23) were given three metered-dose inhaler puffs (600 micrograms) of fenoterol 10 min before induction of anesthesia and placebo-treated patients (n = 22) received three puffs of an aerosol containing no medication. Anesthesia was induced with thiopental and vecuronium intravenously. Respiratory system resistance (Rrs) was measured using a CP-100 pulmonary function monitor 5 min after endotracheal intubation. Inhalation anesthesia was then begun using 50% N2O in O2 with end-tidal 1.3% isoflurane. Rrs measurements were repeated at 5, 15, and 30 min after the initiation of inhalation anesthesia. Postintubation Rrs was significantly lower in the fenoterol-treated patients than in the placebo-treated patients. Rrs declined by a mean of 17.1% after 30 min of inhalation anesthesia in the placebo-treated patients but declined by only 1.4% in the fenoterol-treated patients (P < 0.05 for fenoterol provides protection versus placebo). Our results confirm that fenoterol provides protection against ETT-induced increase of airway resistance. However, isoflurane, while a potent bronchodilator, does not add to the effect of fenoterol.

Adrenergic beta-Agonists↗
PubMed1996

Comparison of the effects of etomidate, propofol, and thiopental on respiratory resistance after tracheal intubation.

BACKGROUND: Tracheal intubation frequently results in reversible bronchoconstriction. Propofol has been reported to minimize this response in healthy patients and in asthma patients, but may be unsuitable for hemodynamically unstable patients for whom etomidate may be preferable. The current study examined respiratory resistance after tracheal intubation after induction with either thiopental, etomidate, or propofol. A supratherapeutic dose of etomidate was used to test the hypothesis that the bronchoconstrictive response could be minimized by deep intravenous anesthesia. METHODS: Seventy-seven studies were conducted in 75 patients. Anesthesia was induced with either 2.5 mg/kg propofol, 0.4 mg/kg etomidate, or 5 mg/kg thiopental. Respiratory resistance was measured at 2 min after induction. RESULTS: Respiratory resistance at 2 min was 8.1 +/- 3.4 cmH2O.1(-1).s (mean +/- SD) for patients receiving propofol versus 11.3 +/- 5.3 for patients receiving etomidate and 12.3 +/- 7.9 for patients receiving thiopental (P < or = 0.05 for propofol vs. either etomidate or thiopental). CONCLUSIONS: Respiratory resistance after tracheal intubation is lower after induction with propofol than after induction with thiopental or after induction with high-dose etomidate.

Adult↗