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Biomedical subjects

C T Yu

Publications and source records attributed to C T Yu.

At least 37 records · Page 2Linked to original sources
PubMed1996

Percutaneous pinning in undisplaced subcapital femoral neck fractures.

Three hundred and five undisplaced subcapital femoral neck fractures managed by pinning in situ with Knowles' pins were evaluated to elucidate the role and effect of such treatment. The protocol of management and follow up, and evaluation, both radiographically and functionally, were set up prospectively. The duration from injury to management was 3.5 (1-14) days, the operation time was 22 (9-48) min and most of the patients were discharged without hospitalization. The follow-up period was 75 (28-136) months. The final results showed 282 (92.5 per cent) fractures united without complications (mean union time: 20 weeks), 14 (4.6 per cent) limbs with non-union, and 9 (2.9 per cent) had implant problems. Twenty-two (7.2 per cent) developed avascular necrosis after union. Percutaneous pinning of undisplaced subcapital femoral neck fractures as day cases is a simple, safe, effective and economic method.

Adult↗
PubMed1996

Increased production of hydrogen peroxide and expression of CD11b/CD18 on alveolar macrophages in patients with active pulmonary tuberculosis.

SETTING: Alveolar macrophages (AM) are important in host defense against Mycobacterium tuberculosis (TB). beta 2-integrins, especially CD11a/CD18 and CD11b/CD18, are implicated in leukocyte migration, antigen presentation, phagocytosis, and production of reactive oxygen species. OBJECTIVE: To explore the functional relevance of beta 2-integrin expression to intracellular H2O2 capacity of AM in TB patients. DESIGN: In a prospective study, AM retrieved from 18 active pulmonary TB patients and 18 normal subjects were assessed for beta 2-integrin expression and intracellular H2O2 metabolism capacity by loading with anti-CD11a/CD18, anti-CD11b/CD18 monoclonal antibodies and 2',7' dichlorofluorescein diacetate (DCFH-DA) respectively, and analyzed by flow cytometry. AM from 8 normal subjects were stimulated with tumor necrosis factor-alpha (TNF-alpha, 10(5) units/ml) to examine the relationship between H2O2 production and CD11b/CD18 expression. RESULTS: The magnitude of DCFH oxidation and CD11b/CD18 expression of AM was higher in TB patients than in normal subjects. The CD11b/CD18 expression was related to the magnitude of DCFH oxidation, but not to lymphocyte numbers or subpopulations (CD4, CD8, CD25). Stimulation of AM with TNF-alpha increased H2O2 production and CD11b/CD18 expression. Pretreatment with CD11b/CD18 monoclonal antibodies inhibited TNF-alpha-induced H2O2. CONCLUSION: AM in TB patients possessed a higher capacity of oxidant metabolism. The increased CD11b/CD18 expression may be related to the increased respiratory burst response in AM against mycobacterial invasion.

Adult↗
PubMed1996

Differential effects of nasal continuous positive airway pressure on reversible or fixed upper and lower airway obstruction.

Our study was to assess whether there were differential effects of nasal continuous positive airway pressure (nCPAP) on different kinds of obstruction in either upper or lower airways in patients with chronic obstructive pulmonary disease (COPD). nCPAP (6 cmH2O for ten minutes) was applied to 7 patients with reversible extrathoracic upper airway obstruction (RUAO) and 3 patients with fixed extrathoracic upper airway obstruction (FUAO). Eighteen stable asthmatics, receiving methacholine challenge to induce a more than 20% reduction in FEV1, were randomly investigated for the effect of nCPAP or sham pressure on reversible lower airway obstruction. Nine stable COPD patients were enrolled to study the effect on irreversible lower airway obstruction. Maximal expiratory and inspiratory flow volume curves and dyspnoea scores were obtained before and after immediate withdrawal of nCPAP. In the RUAO group, nCPAP significantly improved stridor and dyspnoea scores, decreased the ratio of FEF50/FIF50 from 2.05 +/- 0.25 to 1.42 +/- 0.16, and increased peak inspiratory flow (PIF) as well as forced inspiratory vital capacity by 26 +/- 8% and 9 +/- 4%, respectively. In expiratory phase, there was no significant change in pulmonary functions. In asthmatics, nCPAP significantly reversed methacholine-induced bronchoconstriction increasing forced vital capacity by 10 +/- 3%, FEV1 by 15 +/- 4% and PIF by 32 +/- 11%. nCPAP significantly increased the response to bronchodilators. The improvement in airflow rate persisted for at least 5 min after nCPAP withdrawal and was highly correlated with the response to bronchodilators. There was no significant effect of nCPAP on airflow rate in COPD patients. Subjective dyspnoea score changes paralleled the pulmonary function improvement. We conclude that there are differential effects of nCPAP on airflow rates in patients with different nature of airway obstruction. Patients with airway obstruction caused by structural changes may not benefit from the use of nCPAP in improving airflow rates.

Adolescent↗
PubMed1996

Effect of nebulized fenoterol on spirometry, dyspnea sensation changes during exercise in patients with chronic obstructive pulmonary disease.

Airflow limitation impairs exercise capacity in patients with chronic obstructive pulmonary disease (COPD). Bronchodilators have been shown to increase exercise tolerance in patients with COPD by mechanisms yet unclarified. We studied the effect of nebulized fenoterol (0.5 mg/ml) on the 6-minute walking test (WT) 60 mins after a control WT using a nebulized saline control in 16 patients with moderate to severe COPD. Before and immediately after each WT, the FEV1, FVC, O2, Saturation and dyspnea score (Borg breathlessness score,[BS]) were measured. Fenoterol had no significant effect on pre-exercise spirometry in our patients but maintained a significantly higher level of FEV1 (0.9 +/- 0.1L, p < 0.0001) and FVC (2.0 +/- 0.2L, p < 0.01) immediately after exercise than that after saline control nebulization (0.7 +/- 0.1L, 1.8 +/- 0.2L, respectively). Fenoterol significantly (p < 0.01) increased walking distance (WD) from 201.3 +/- 22.2m to 238.9 +/- 22.2m, but no difference was found in BS and oxygen saturation. The decline in FEV1 following the WT was shown to have an inverse relationship (r = - 0.74, p < 0.002) with the WD improvement (delta WD). Those who walked farther after fenoterol inhalation felt less dyspnea after exercise, also with an inverse correlation (r = -0.61, p < 0.02). These results suggest that fenoterol may improve exercise capacity by preventing airflow deterioration during exercise in patients with COPD. We also recommend the 6-minute walking test in the routine clinical assessment of COPD patients to evaluate the symptomatic benefit offered by betamimetic bronchodilators.

Adrenergic beta-Agonists↗
PubMed1995

Effect of nasal continuous positive airway pressure on methacholine-induced bronchoconstriction.

Bronchial hyper-responsiveness is a cardinal feature of asthma. To determine whether nasal continuous positive airway pressure (NCPAP) influences airway smooth muscle in response to exogenous stimuli, we examined the effect of NCPAP on aerosolized methacholine-induced bronchoconstriction in 16 stable asthmatic patients. The dose-response curve for each subject was measured by a log transformation and linear regression analysis as well as a formula fitted to the data points to obtain values for a (slope) and b (position). The PD20FEV1 significantly increased in patients receiving 8 cmH2O of NCPAP by one doubling dose compared with that in patients using sham pressure. NCPAP shifted the dose-response curves to be flatter, deviated upwards and to the right. The coefficient a, indicating bronchial reactivity, was significantly lower in patients receiving NCPAP. The coefficient b, indicating the bronchial sensitive threshold, was higher after applying NCPAP. In contrast, coefficients a and b did not change in subjects with sham pressure. NCPAP also significantly enhanced the bronchodilator effect of inhaled salbutamol in response to methacholine-induced bronchoconstriction. In summary, we have shown that NCPAP therapy improves bronchial smooth reactivity with an increase in PD20FEV1 and a reduction in the bronchial reactivity and bronchial sensitivity. Therefore, NCPAP may provide an adjuvant therapy in patients with acute bronchial asthma.

Acute Disease↗
PubMed1995

White as a reporter gene to detect transcriptional silencers specifying position-specific gene expression during Drosophila melanogaster eye development.

The white+ gene was used as a reporter to detect transcriptional silencer activity in the Drosophila genome. Changes in the spatial expression pattern of white were scored in the adult eye as nonuniform patterns of pigmentation. Thirty-six independent P[lacW] transposant lines were collected. These represent 12 distinct pigmentation patterns and probably 21 loci. The spatial pigmentation pattern is due to cis-acting suppression of white+ expression, and the suppression probably depends on cell position rather than cell type. The mechanism of suppression differs from inactivation by heterochromatin. In addition, activation of lacZ in P[lacW] occurs also in specific patterns in imaginal discs and embryos in many of the lines. The expression patterns of white+ and lacZ may reflect the activity of regulatory elements belonging to an endogenous gene near each P[lacW] insertion site. We speculate that these putative POSE (position-specific expression) genes may have a role in pattern formation of the eye as well as other imaginal structures. Three of the loci identified are optomotor-blind, engrailed and invected. teashirt is also implicated as a candidate gene. We propose that this "silencer trap"' may be an efficient way of identifying genes involved in imaginal pattern formation.

ATP-Binding Cassette Transporters↗
PubMed1995

Morphine inhibits spontaneous and cytokine-enhanced natural killer cell cytotoxicity in volunteers.

BACKGROUND: Opioids are used by patients who have conditions ranging from the acute pain of surgery and chronic cancer pain to substance abuse. Despite their widespread use and considerable experimental data about them, little is known about how opioids may alter in vivo immunity in humans. This study was designed to evaluate the in vivo effect of morphine on human peripheral blood immune functions. METHODS: Healthy volunteers underwent continuous exposure to morphine for 36 h including a 24-h intravenous infusion in the hospital. Peripheral blood was drawn for immune function studies at five measurement times before, during, and after morphine exposure. Peripheral blood mononuclear cells were tested for acute and gamma-interferon-stimulated natural killer cell cytotoxicity (NKCC), antibody-dependent cell cytotoxicity, antibody Fc receptor expression, and human immunodeficiency virus infectivity. RESULTS: Significant suppression of NKCC was observed at 2 and 24 h after the onset of intravenous morphine exposure. Suppression of NKCC persisted for 24 h after termination of morphine infusion in a "high"-dose study group. gamma-Interferon-stimulated NKCC and antibody-dependent cell cytotoxicity were also decreased after 24 h of intravenous morphine exposure. No effect on Fc receptor expression was observed. Mean virus antigen production after lymphocyte infection with human immunodeficiency virus was not increased (p24 100 ng/ml after morphine vs. 43 ng/ml before morphine; P = 0.17). CONCLUSIONS: These results suggest that morphine administration, at doses within the range of analgesic use, can cause measurable suppression of some components of the human cellular immune system.

Adult↗
PubMed1995

Relation of bronchoalveolar lavage T lymphocyte subpopulations to rate of regression of active pulmonary tuberculosis.

BACKGROUND: Effective host defence against mycobacterial infection chiefly depends on the interactions between macrophages and T lymphocytes. This study investigated the relation of cellular components and their activity of cells obtained by bronchoalveolar lavage (BAL) from the lower respiratory tract to disease regression in patients with active pulmonary tuberculosis without HIV infection. METHODS: Clinical indices including age, sex, the presence of diabetes, fever, the presence of resistant strains of mycobacteria, the bacterial load in sputum, and disease extent on chest radiography at presentation were assessed before commencing four-drug antituberculous therapy. Twenty two patients with active pulmonary tuberculosis were divided into rapid, intermediate, and slow regression groups. Subpopulations of alveolar macrophages separated using discontinuous Percoll density gradient centrifugation and T lymphocytes (with CD3, CD4, CD8, and CD25 monoclonal antibodies) were quantified. RESULTS: There were no differences among rapid, intermediate, and slow regression groups in terms of age, sex, the presence of diabetes, the presence of resistant strains of mycobacteria, or the bacterial load in sputum. No differences were found between the groups in terms of subpopulations of alveolar macrophages or numbers of CD3 and CD4 lymphocytes. By contrast, an increase in CD8 cells was shown in the slow regression group compared with the rapid and intermediate regression groups. CD25 cell numbers were increased in the rapid regression group compared with the slow regression group. The CD4/CD8 ratio was decreased in the slow regression group compared with the rapid and intermediate regression groups and the relation between the proportion of CD25 cells and the CD4/CD8 ratio in BAL fluid was significant. CONCLUSIONS: A decreased CD4/CD8 ratio with an increase in CD8 cells in the alveolar spaces was associated with slow disease regression in patients with active pulmonary tuberculosis without HIV infection, suggesting that the balance of T lymphocyte subsets may play a central part in the modulation of host defence against mycobacterial infection.

Antitubercular Agents↗
PubMed1994

Differential effects of luminol, nickel, and arsenite on the rejoining of ultraviolet light and alkylation-induced DNA breaks.

When Chinese hamster ovary cells were treated with ultraviolet (UV) light or methyl methanesulfonate (MMS), a large number of DNA strand breaks could be detected by alkaline elution. These strand breaks gradually disappeared if the treated cells were allowed to recover in a drug-free medium. The presence of nickel or arsenite during the recovery incubation retarded the disappearance of UV-induced strand breaks, whereas the disappearance of MMS-induced strand breaks was retarded by the presence of arsenite or of luminol, a new inhibitor for poly(ADP-ribose) synthetase. Luminol, however, had no apparent effect on the repair of UV-induced DNA strand breaks, and nickel had no effect on the repair of MMS-induced DNA strand breaks. When UV- or MMS-treated cells were incubated in cytosine arabinofuranoside (AraC) plus hydroxyurea (HU), a large amount of low molecular weight DNA was detected by alkaline sucrose sedimentation. The molecular weight of these DNAs increased if the cells were further incubated in a drug-free medium. This rejoining of breaks in cells pretreated with UV plus AraC and HU was inhibited by nickel and by arsenite, but not by luminol. The rejoining of breaks in cells pretreated with MMS plus AraC and HU was inhibited by luminol and by arsenite, but not by nickel. These results suggest that different enzymes may be used in DNA resynthesis and/or ligation during the repairing of UV- and MMS-induced DNA strand breaks, and that nickel, luminol, and arsenite may have differential inhibitory effects on these enzymes.

Alkylation↗
PubMed1994

Hypodense eosinophil number relates to clinical severity, airway hyperresponsiveness and response to inhaled corticosteroids in asthmatic subjects.

The phenotypically distinct low-density eosinophil, with its greater inflammatory potential, is increased in asthma. However, the role of hypodense eosinophils in the development of asthma is still unclear. We conducted a double-blind, placebo-controlled study to examine the effect of inhaled corticosteroids on the number of hypodense eosinophils in 27 asthmatic subjects and its relationship with clinical severity. The density profile of eosinophils in the peripheral blood was determined using Percoll density gradient fractionation. Eosinophils recovered from asthmatics were mainly in the lower density fractions (< 1.095 g.ml-1) (63 +/- 3%; n = 27), significantly different from those of normal subjects (27 +/- 2%; n = 7). The proportion of hypodense eosinophils was inversely related to the provocative concentration of methacholine producing a 20% fall in forced expiratory volume in one second (PC20) value (r = -0.75). Patients with mild asthma had a lower percentage of hypodense eosinophils (45 +/- 4%; n = 14) than those with moderate asthma (67 +/- 3%; n = 13). Inhalation of budesonide (800 micrograms.day-1) (n = 15) for 4 weeks, but not placebo, significantly improved the PC20 values by 0.97 doubling dose, forced expiratory volume in one second (FEV1) % predicted by 17%, and peak expiratory flow rate (PEFR) by 15%, and decreased PEFR diurnal variability by 5.4%. The percentage of hypodense eosinophils was significantly decreased from 68 +/- 4 to 47 +/- 4% in the budesonide group (n = 15), but not in the placebo group (n = 12) (63 +/- 4 to 65 +/- 4%).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗
PubMed1994

[Clinical application of LED pattern visual evoked potential].

The light emitting diode (LED) stimulator was used to record PVEP from 59 eyes (38 patients) with optic neuropathy and 46 eyes (23 patients) with cataract. The amplitude and the latency of P100 in LED PVEP were comparable to those in TV PVEP with insignificant differences (P > 0.05), suggesting that LED PVEP may be used in the evaluation of visual function and prognosis of patients with optic neuropathy or cataract.

Cataract↗
PubMed1993

Nickel chloride inhibits the DNA repair of UV-treated but not methyl methanesulfonate-treated Chinese hamster ovary cells.

Nickel, a human carcinogen, has been shown to enhance the cytotoxicity, mutagenicity, and sister-chromatid exchanges (SCE) induced by ultraviolet (UV) light but not by methyl methanesulfonate (MMS). To verify that the cocytotoxicity and cogenotoxicity of nickel are correlated with its inhibition on DNA repair, the effects of nickel on the DNA repair induced by UV and by MMS have been investigated. Our analyses of DNA repair of single-strand breaks by alkaline elution and alkaline sucrose sedimentation indicate that nickel inhibited the DNA repair in UV-treated, but not in MMS-treated cells. Therefore, the inhibition of DNA repair seems to play an important role in the cocytotoxicity and comutagenicity of nickel. However, the inhibition of DNA repair seems not to play a decisive role in enhancing SCE, because we have previously shown that arsenite inhibits the UV-induced DNA repair, but has no enhancing effect on the UV-induced SCE. Our results also show that nickel had obvious inhibitory effects on DNA ligation and postreplication repair, but had no apparent effect on nucleotide excision and DNA polymerization in the UV repair. The results of the DNA ligation inhibition by nickel in UV but not in MMS repair suggest that different ligases are used in the DNA repair of UV- and MMS-induced damages.

Animals↗
PubMed1993

Alveolar macrophage subpopulations in patients with active pulmonary tuberculosis.

Alveolar macrophages are a heterogeneous cell population. The heterogeneity of alveolar macrophages recovered by bronchoalveolar lavage (BAL) from 12 patients with active pulmonary tuberculosis (TB) and 10 normal subjects was studied using Percoll density fractionation. The numbers and subsets (on the basis of CD3, CD4, and CD8 monoclonal antibodies) of lymphocytes in BAL were measured by flow cytometry. Alveolar macrophages recovered from patients with TB were mainly in the lower-density fractions (< 1.030 and 1.030 to 1.040 g/ml), whereas alveolar macrophages from normal subjects were in the higher-density fractions (1.050 to 1.070 and > 1.070 g/ml). There were no significant differences in alveolar macrophages' repartition between smokers and nonsmokers in either patients with TB or normal subjects. The significant changes in the proportions of the lowest fraction and the higher fractions of alveolar macrophages in patients with TB were not altered after division of our patients into smoker and nonsmoker subgroups when compared with corresponding subgroups in normal subjects. The proportion of the alveolar macrophages in the lowest fraction was inversely related to the bacterial load of sputum and the disease extent on chest radiography in TB patients. The CD4/CD8 ratio was significantly higher in patients with TB. This study shows that alveolar macrophages from TB patients are heterogeneous with hypodense cells predominant probably by interaction with T lymphocytes. Changes in the proportions of alveolar macrophages within subpopulations may be of critical importance in determining the overall response of the lung to TB infection.

Bronchoalveolar Lavage Fluid↗
PubMed1993

Epiphyseal fracture-retrosternal dislocation of the medial end of the clavicle: a case report.

Epiphyseal fracture-retrosternal dislocation of the medeial end of the clavicle is an unusual injury. It may occur as a result of a blow either indirectly on the posterolateral aspect of the shoulder girdle or directly over the sternal end of the clavicle. It is clinically impossible to differentiate from the true posterior dislocation even with the computed tomography, but the treatment for either lesion is the same. Recently we uneventually treated a 15-year-old boy with conservative treatment and got a satisfactory result. The purpose of this paper is to draw the attention of the readers to the rarity and serious nature of such injury and the potential difficulties in establishing diagnosis and achieving reduction.

Adolescent↗
PubMed1993

[Analgesic effect of tramadol HCL in ESWL].

Since its introduction, extracorporeal shock-wave lithotripsy (ESWL) has become the treatment of choice in patients with urinary calculi. But the pain during ESWL is intolerable for many patients. Tramadol HCL resembles morphine in that it depresses motor and sensory responses of the spinal nociceptive system by a spinal and a supraspinal action. The side effects of tramadol are less than morphine. A prospective study was performed to determine the effect of tramadol in ESWL for the patients with urinary tract calculi. Ninety patients were randomized divided into three groups. Group A 40 patients (male:female = 31:9) received oral tramadol HC1 100 mg; group B 17 patients (male:female = 12.5) received multi-vita; group C 33 patients (male:female = 26:7) received analgesic (contained aspirin 399 mg and codeine phosphate 15 mg). The patients took the drugs 30 minutes before ESWL. The patients with renal calculi > 2 cm in diameter or ureteral calculi > 1 cm in diameter were excluded. The lithotriper used in our hospital is Siemens Lithostar. According to the description of the patients postoperatively, the pain intensity during ESWL was identified with Verbal Scale and Visual Analogue Scale (VAS). The statistical method is one-way ANOVA. Statistical difference is significant when p < 0.05. The mean age of patients group A is 46.5 +/- 17.1, group B 45.5 +/- 14.4, and group C 50.5 +/- 14.6. The mean diameter of urinary calculi of group A is 0.98 +/- 0.41 cm, group B 1.09 +/- 0.33, and group C 1.06 +/- 0.43.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Effect of morphine and beta-endorphin on human Fc receptor-dependent and natural killer cell functions.

Interactions between opiates and the human immune system have important clinical implications. To further evaluate these interactions, we studied in vitro and in vivo effects of morphine sulfate (morphine) and beta-endorphin (Bend) on antibody-dependent cell cytotoxicity (ADCC), natural killer cell cytotoxicity (NKCC), and effector cell expression of antibody Fc receptors. Morphine and Bend had no potent in vivo or in vitro effect on FcR expression nor did they have a significant in vitro effect on ADCC by monocytes or polymorphonuclear cells. Bend enhancement of NKCC in vitro was inhibited by coincubation of effector cells with morphine. After taking 90 to 150 mg of oral morphine, study volunteers demonstrated a significant decrease in ADCC by peripheral blood mononuclear cells. The same individuals demonstrated a consistent increase in NKCC and no change in the expression of Fc receptors. Effector cells from these individuals responded normally to in vitro incubation with interferon-gamma (IFN-gamma).

Antibody-Dependent Cell Cytotoxicity↗
PubMed1992

Effect of arsenite on the DNA repair of UV-irradiated Chinese hamster ovary cells.

Arsenite, an ubiquitous human carcinogen, has been shown to enhance the cytotoxicity, mutagenicity and clastogenicity of UV light in mammalian cells. Arsenite may exert its co-genotoxic effects by inhibiting DNA repair. Results from alkaline sucrose gradient sedimentation show that arsenite did not accumulate UV-induced DNA strand breaks in Chinese hamster ovary (CHO) K1 cells as aphidicolin plus hydroxyurea (HU) did. These data indicate that arsenite did not inhibit the activity of DNA polymerase alpha in UV repair. Treatment with arsenite before UV irradiation slightly reduced the DNA strand breaks accumulated by cytosine beta-D-arabinofuranoside (AraC) plus HU. This effect implies that arsenite only slightly inhibited the incision of UV-induced DNA adducts. The low molecular weight DNA accumulated by post-UV incubation with AraC plus HU shifted to high molecular weight upon the incubation of cells in drug-free medium, but this shifting was prohibited by the presence of arsenite. This suggests that arsenite inhibited the rejoining of DNA strand breaks. When a pulse-chase labelling procedure was applied on UV-irradiated cells, the chain elongation of nascent DNA was strongly inhibited by post-incubation with arsenite. These data show that arsenite inhibited post-replication repair in UV-irradiated cells. Therefore, the steps inhibited by arsenite in UV-induced DNA repair in CHO K1 cells are different from human fibroblasts in which the inhibition of excision of pyrimidine dimers by arsenite was reported to be the major target.

Animals↗