Biomedical subjects

C T Liu

Publications and source records attributed to C T Liu.

At least 37 records · Page 2Linked to original sources

PubMed1997

Effects of inhibitors of serine protease, phenoloxidase and dopa decarboxylase on the melanization of Dirofilaria immitis microfilariae with Armigeres subalbatus haemolymph in vitro.

The melanization of Dirofilaria immitis microfilariae in Armigeres subalbatus haemolymph in vitro is a two-step process. Firstly, the microfilariae are encased in a transparent capsule, then the capsule material is melanized later. Benzamadine HC1 and p-amidinophenylmethanesulfonyl fluoride, both serine protease inhibitors, inhibited the deposition of the transparent capsule material and melanization. Diethyldithiocarbamate, a phenoloxidase inhibitor, did not prevent the deposition of the transparent capsule material but it did inhibit melanization. m-Hydroxybenzylhydrazine, a dopa decarboxylase inhibitor, had no inhibitory action on the deposition of the transparent capsule material. However, the time for the transparent capsule to become melanized was delayed due to the presence of m-hydroxybenzylhydrazine in the test system. Immmunocytochemical localization showed that propheoloxidase and/or phenoloxidase was present in the transparent capsule material. These results suggest (1) that prophenoloxidase cascade is essential in the melanization of microfilariae in mosquitoes and its putative activation behaviour is similar to that of other insects and (2) that the deposition of transparent capsule material is the result of the activation of prophenoloxidase by serine proteases and the melanization of the transparent capsule material is due to the presence of active phenoloxidase in capsule.

Animals↗

PubMed1996

Lidocaine-induced CNS toxicity--a case report.

Lidocaine is the first local anesthetic of the amide type to be introduced to clinical practice. It is a versatile drug and in anesthesia, is the most commonly used local anesthetic because of its aptness of potency, rapid onset, moderate duration of action and topical activity. It is relatively safe and useful in many other clinical settings. Unfortunately, systemic intoxication and psychotic reaction associated with its use often occur because of its popularity and wider safety margin, for which guide in use is often ignored and overdose becomes commonplace. Moreover, due to its universality in use seldom reports have recently dealt with lidocaine, particularly regarding its toxic reaction. Here, we present a case of lidocaine intoxication occurring during circumcision for a reviewal of the problem. A healthy young male, weighing 65 kg, underwent circumcision for phimosis under penile block with 2% lidocaine which totaled 600 mg. Twenty minutes after injection the patient developed headache, tinnitus, visual and auditory disturbances. Muscle twitching over the mouth angles, trismus and rigidity of extremities were also noted. Later in the course he became restless, agitative, hallucinative, talkative, and verbose with repetitious words. The whole course of the disorder lasted about 5 h. It was believed that lidocaine-induced CNS intoxication, manifested by psychotic reaction broke out. Treatment with thiopental was not very impressive. Also, we took this opportunity to discuss and review the toxic reaction associated with the use of lidocaine, its risk factors, mechanism, treatment and prevention. The complicated associations of lidocaine-induced CNS toxic reaction with central control of behavior and the neurotransmitter systems (adrenergic, dopaminergic and serotonin) were also touched.

Adult↗

PubMed1995

Role of atrial natriuretic peptide in disturbed water and electrolyte metabolism of guinea pigs infected with Pichinde virus.

Daily intake and output of water and electrolytes (Na+, K+, and Cl-) were determined for 14 days in control and Pichinde virus-infected strain-13 guinea pigs. Although water intake began to decrease 7 days after virus inoculation, total daily water output (insensible water loss, urine excretion, plus fecal water loss) had little change. However, insensible water loss alone increased markedly in the virus-infected animals. Both intake and excretions of urinary and fecal electrolytes decreased at the middle (days 7 to 10) and late (days 11 to 14) stages of viral infection. Differences between intake and output of water and electrolytes were reduced significantly during these periods. To determine a possible relationship between atrial natriuretic peptide (ANP) and urinary Na+ and water excretion over intake, we measured plasma ANP concentrations. The mean control value of plasma ANP was 24 +/- 1.0 pg/ml, and plasma ANP concentrations of infected animals increased significantly (P < 0.01) to 49.5 +/- 3.9 and 51.3 +/- 8.8 pg/ml on postinoculation days 7 and 12. Because the overall physiologic responses to Pichinde virus infection are complicated, it is difficult to postulate a single central theme concerning the pathogenesis. Nevertheless, we hypothesize that the virus-induced invisible tissue "biochemical lesions" and the consequential release of mediators and hormones were possible causes of death. Among other pathophysiologic mechanisms, the increased plasma ANP concentration may have played a role in the development of disturbed water and electrolytes metabolism during Pichinde virus infection.

Animals↗

PubMed1994

[Teaching sociology in medical school].

As early as in 1994 medical education was criticised by the Royal College of Physician in London. Nevertheless until 1978 D. C. Maddision was still asking the question: "What's wrong with medical education?", and Abrahamson writing a paper called "Disease of the (medical) curriculum". Since the 1950s social and behavioural sciences have been gradually brought into the curriculum in order to pursue better medical care. In the 1970s critics of medicine went beyond its economical and political aspects, ie. its maldistribution etc., to its cultural side. Not only the efficacy of modern medicine but its moral neutrality and benevolence were called into question. This paper is mainly based on the writer's personal experience of teaching sociology and medical sociology in a medical school in Taiwan. The debate on relevance, the difficulties and problems in teaching and suggestions for the future are covered.

Education, Medical↗

PubMed1994

Clinical application of 131I-HIPDM in the patients with chronic obstructive pulmonary disease.

N,N,N'-trimethyl-N'-2 hydroxy-3-methyl-5-iodobenzyl-1,3-propanediamine iodine-131 (HIPDM) as a lung imaging and metabolic tracer in patients with chronic obstructive pulmonary disease (COPD) were used. 0.4 mCi 131I-HIPDM was rapidly injected into the antecubital vein. The imaging of 131I-HIPDM in the lung was different in various groups. 131I-HIPDM of the clearance by the lungs was a biphasic curve (rapid phase and slow phase). It was displayed that rapid phase of the clearance curve of 131I-HIPDM in the lungs in subjects with chronic obstructive pulmonary emphysema, especially those of smokers were very slow. The rapid phase of the 131I-HIPDM of the right lung clearance was significantly correlated with Forced Vital Capacity (FVC), Forced Expiratory Volume in the first second (FEV1), Functional Residual Capacity (FRC), Residual Volume (RV), Total Lung Capacity (TLC) p < 0.01; Peak Expiratory Flow Rate (PEFR), Vital Capacity (VC), Maximum Ventilatory Volume (MVV), Arterial oxygen tension (PaO2) p < 0.05. Smoking influence on clearance of 131I-HIPDM of the lung including normal smokers with normal lung function. It was considered that the analysis of the lung release of 131I-HIPDM forms a new lung dysfunction index and it was useful that found early lung damage.

Adult↗

PubMed1994

Prolonged lung retention of 131I-HIPDM in smokers.

Thirty-five subjects were divided into 4 groups; the first group was composed of 8 healthy nonsmoking subjects; the second group included 8 healthy smokers; the third group included 12 nonsmoking patients suffering from chronic obstructive pulmonary emphysema; the fourth group was composed of 7 smokers with chronic obstructive pulmonary emphysema. N,N,N'-trimethyl-N'2-Hydroxy-3-Methyl-5-iodobenzyl-1,3-propanediamine iodine-131(HIPDM) was rapidly injected into the antecubital vein. The influence of 131I-HIPDM by lung clearance was analysed thought imaging of lung and ratio of prolongation of 131I-HIPDM in the lung. Prolongation of 131I-HIPDM in the lung was shown in the smokers with chronic obstructive pulmonary emphysema in 60 minutes, and the healthy smokers, smokers with chronic obstructive pulmonary emphysema in the 24 hours after the injection of 131I-HIPDM. Smoking is an important factor of disturbance of lung clearance.

Adult↗

PubMed1994

Cardiovascular and pulmonary responses to Pichinde virus infection in strain 13 guinea pigs.

In fatal human Lassa fever, severe hypotension, circulatory shock, and pulmonary edema develop as terminal events. We examined cardiovascular and respiratory functions in strain 13 guinea pigs infected with Pichinde virus, an animal model for studying human Lassa fever. Cardiovascular functions were studied in anesthetized and conscious guinea pigs, whereas pulmonary functions were measured only on animals under anesthesia. In anesthetized animals, cardiovascular disturbances were severe and progressive from postinoculation day (PID) 10. Cardiac output, measured by thermodilution, decreased 28 to 53% below baseline values from PID 10 to 12 and was accompanied by a gradual reduction of mean arterial blood pressure and heart rate. Although left ventricular systolic pressure decreased significantly, the left ventricular +dp/dtmax and -dp/dtmax decreased only slightly on PID 12. Similar depressed cardiovascular responses were observed in conscious animals infected with Pichinde virus. Changes included decreased cardiac output, heart rate, cardiac work, cardiac power, and stroke volume, as well as increased total peripheral resistance and prolonged mean transit time. We postulate that a global cardiovascular dysfunction with the involvement of right and left sides of the heart may be the main cause of irreversible circulatory deterioration and death during Pichinde virus infection in strain 13 guinea pigs.

Animals↗

PubMed1993

The effects of growth hormone and insulin-like growth factors I and II on glutamine metabolism by skeletal muscle of the rat in vitro.

Soleus muscle preparations of the rat were incubated in the presence of growth hormone, IGF-I or IGF-II. Growth hormone (10 and 100 ng/ml) increased, but IGF-I and IGF-II were without effect on the concentration of glutamine in soleus muscle. Growth hormone was without effect on the rate of release of glutamine from muscle. In contrast, the rate of release of glutamine was decreased in the presence of IGF-I (750 ng/ml) and increased in the presence of IGF-II (250 and 750 ng/ml). Growth hormone and the IGFs may therefore play an important role in the control of glutamine metabolism by skeletal muscle.

Amino Acids↗

PubMed1993

Changes in platelet-activating factor, catecholamine, and serotonin concentrations in brain, cerebrospinal fluid, and plasma of pichinde virus-infected guinea pigs.

Brain concentrations of platelet-activating factor (PAF), catecholamines, and serotonin were measured in control and Pichinde virus-infected strain 13 guinea pigs on postinoculation day (PID) 12. After virus inoculation, PAF concentrations increased 81% in cerebrum, 147% in diencephalon-brain stem, and 110% in cerebellum from baseline values of 2.6 +/- 0.3, 4.3 +/- 0.2, and 6.1 +/- 0.5 (ng/g wet tissue), respectively. Dopamine concentrations in the infected cerebrum and diencephalon-brain stem increased significantly, whereas norepinephrine concentration increased only in cerebrum. However, serotonin concentrations in all three regions of infected brain decreased significantly as compared with control values. There were no significant changes in epinephrine concentrations of infected brain. Norepinephrine and epinephrine concentrations in plasma and cerebrospinal fluid on PID 7 and 12 increased significantly as compared with control values, while plasma dopamine concentration increased significantly on PID 7. Increased brain PAF, dopamine, and and norepinephrine concentrations with decreased brain serotonin concentrations may mediate the hyperactivity of the hypothalamic-pituitary-adrenal axis and involve some unknown pathophysiologic processes of arenaviral infection. Furthermore, increased plasma catecholamine concentrations are associated with stress and may be partially responsible for the development of cardiovascular dysfunction and pulmonary edema during this viral disease.

Animals↗

PubMed1993

Platelet-activating factor (PAF)-induced cardiopulmonary dysfunctions and their reversal with a PAF antagonist (BN 52021) in strain 13 guinea pigs.

Cardiovascular and respiratory responses to a 2 h intravenous constant infusion of PAF (5 and 10 ng/kg per min) were studied in strain 13 guinea pigs. PAF decreased arterial blood pressure, left systolic ventricular pressure, and cardiac output (CO). These cardiovascular changes were dose-dependent. The PAF-induced hypotension returned to a pre-infusion level spontaneously with increased total peripheral resistance despite continuous infusion of PAF. The decreased CO was most striking, and did not recover to pre-infusion levels due to depressed cardiac contractility and impaired ventricular relaxation. Respiratory responses to PAF infusion at these doses were mild and only occurred after serious cardiovascular dysfunctions developed. A higher dose of PAF (20 ng/kg per min) produced drastically decreased CO and dynamic lung compliance (Cdyn), increased pulmonary airway resistance, hypoventilation and apnea within 10-40 min. BN 52021, a PAF receptor antagonist, administered as a single i.v. dose (6 mg/kg) 15 min after PAF infusion, reversed most of cardiopulmonary dysfunctions and prevented death by increasing cardiac contractility, CO, and minute volume from extremely low values. The data suggest that marked cardiopulmonary disturbances induced by intravenous PAF infusion reflects certain pathophysiological mechanisms of diseases that may involve the cellular release of PAF. The administration of BN 52021 or other potent PAF antagonists may be beneficial under these circumstances.

Animals↗

PubMed1992

The effect of insulin-like growth factor II on glucose uptake and metabolism in rat skeletal muscle in vitro.

The effect of insulin-like growth factor II (IGF II) on the rates of lactate formation, glycogen synthesis and glucose transport in the presence of a range of concentrations of insulin were investigated using an isolated preparation of rat skeletal muscle. IGF II, at a concentration of 65 ng/ml, caused a small but significant increase in the rates of these processes at a basal physiological insulin concentration (10 muunits/ml), but was without effect in the presence of 1, 100, 1000 or 10,000 muunits of insulin/ml. Hence IGF II increased the insulin sensitivity of this tissue. This effect was removed if the incubation medium was supplemented with an equimolar concentration of IGF binding protein 1 (BP1). It is suggested that changes in the concentration of IGF II and/or BP1 may regulate glucose uptake and metabolism in skeletal muscle and have physiological significance in the control of blood glucose level.

Animals↗

PubMed1992

Metabolism of platelet-activating factor in neutrophils isolated from Pichinde virus-infected guinea pigs.

Metabolism of platelet-activating factor (PAF) was studied in cultured polymorphonuclear neutrophils (PMNs) obtained from Pichinde virus-infected strain 13 guinea pigs. Neutrophils obtained from control and infected guinea pigs on postinoculation days 10 and 14 were incubated with [3H]lyso-PAF, [3H]PAF, or [3H]acetate. After incubation for 1 h at 37 degrees C, formation of [3H]acyl-PAF from either [3H]lyso-PAF or [3H]PAF increased significantly in PMNs from infected guinea pigs compared to control PMNs. Furthermore, total radioactivity from [3H]lyso-PAF or [3H]PAF was higher in PMNs from infected animals than in those from controls. However, compared to PAF production by control PMNs, production of PAF by infected PMNs was unchanged. These results suggest that PMNs may not be the major source of increased blood PAF levels during Pichinde viral disease.

Acetates↗

PubMed1992

Possible involvement of endogenous beta-endorphin in the pathophysiological mechanisms of Pichinde virus-infected guinea pigs.

Previously, we demonstrated that naloxone, an opiate antagonist, prolonged survival of strain 13 guinea pigs infected with Pichinde virus. Thus, endogenous opiates may be involved in the pathogenesis of this viral disease. To determine whether endogenous opiate levels were affected by Pichinde viral infection, beta-endorphin concentrations in plasma and cerebrospinal fluid (CSF) of normal and infected strain 13 guinea pigs were measured by radioimmunoassay. Cerebrospinal fluid beta-endorphin concentrations were 78.0 +/- 13.2 pg/ml on postinoculation day (PID) 7, 59.0 +/- 5.6 pg/ml on PID 12, and 58.8 +/- 5.4 pg/ml on PID 14. These values were significantly higher than baseline levels of CSF beta-endorphin: 30.8 +/- 1.9 pg/ml. Plasma beta-endorphin concentrations of infected animals increased significantly to 202.1 +/- 17.9 pg/ml on PID 7 and to 154.2 +/- 21.4 pg/ml on PID 12 from a mean baseline value of 84.2 +/- 13.1 pg/ml. After a primer intravenous injection of beta-endorphin (10, 15, or 30 micrograms/kg), followed by constant infusion of beta-endorphin (15, 45, or 90 micrograms/kg.hr) to control noninfected guinea pigs, heart rate (except with the lowest dose) and mean blood pressure decreased markedly. Under these experimental conditions, concentrations of plasma and CSF beta-endorphin increased simultaneously with different magnitude. Because both Pichinde viral infection and beta-endorphin administration produced a similar trend of cardiovascular disturbances, leading to hypotension and bradycardia, increased concentrations of plasma and CSF beta-endorphin may play a partial role in the pathophysiological mechanisms of Pichinde virus infection.

Animals↗

PubMed1992

[Clinical evaluation of the metabolism and imaging of the lung in the patients with chronic obstructive pulmonary diseases using 131I-HIPDM].

The accumulation of venously injected 131I-HIPDM in the rat lung was observed. In this article we report the results of application of 131I-HIPDM in the patients with COPD. The results showed that the metabolism and development of 131I-HIPDM in the lung reflected on condition of the pulmonary endothelial cells or receptors. The clearance curve of HIPDM displayed that COPD, especially COPD of smokers was slow. The analysis of the lung clearance of 131I-HIPDM forms a new index of lung dysfunction.

Adult↗

PubMed1992

Cardiovascular responses to intracerebroventricular infusion of artificial cerebrospinal fluid in anesthetized strain 13 guinea pigs.

The cardiovascular effects of constant intracerebroventricular infusion in anesthetized strain 13 guinea pigs were studied. Bilateral cerebroventricles of the animals were catheterized stereotaxically with two 20-gauge blunt needles, penetrating 5 to 6 mm into the skull. Baseline cerebroventricular pressure values were 1.3 +/- 0.6 mmHg. After artificial cerebrospinal fluid was infused into the left ventricle at 0.5 ml/h, left cerebroventricular pressure increased to 8.1 +/- 1.6 mmHg (P less than 0.01), while right cerebroventricular pressure reached 5.6 +/- 2.2 mmHg within 20 minutes. No significant changes in mean blood pressure or heart rate were observed. When intracerebroventricular infusion rate increased to 5.0 ml/h, cerebrospinal fluid pressures of left and right cerebroventricles increased to 40.0 +/- 4.8 and 38.4 +/- 4.7 mmHg within 10 minutes from baseline values of 1.5 +/- 0.5 and 1.7 +/- 0.7 mmHg, respectively. Simultaneously, mean blood pressure and heart rate increased from 72 +/- 4 to 101 +/- 9 mmHg and from 195 +/- 11 to 218 +/- 17 beats/min, respectively. However, 30 to 50 minutes later, mean blood pressure, heart rate, and cerebrospinal fluid pressure decreased abruptly, and two of four animals died. We suggest that this technique with a low infusion rate (less than 0.5 ml/h) can be used to deliver certain drugs into the brain ventricles directly without producing undesirable effects on blood pressure or heart rate.

Anesthesia↗

PubMed1992

Increased platelet-activating factor (PAF) concentrations in hearts and lungs of Pichinde virus-infected guinea pigs.

Platelet-activating factor (PAF) has been implicated as a cause of cardiopulmonary disturbances in certain diseases. In the present study, concentrations of PAF in hearts, lungs, whole blood, and other organs of control and Pichinde virus-infected guinea pigs on post-inoculation days (PID) 10 and 14 were measured by radioimmunoassay. Results were further confirmed by bioassay after separation and purification with thin-layer chromatography. PAF concentration in the hearts and lungs of virus-infected animals increased significantly on PID 10 and 14, as compared with control levels. PAF level in the blood of infected guinea pigs also significantly increased on PID 14. There was little change of PAF levels in liver and kidney after viral inoculation. Increased PAF concentrations in both hearts and lungs of infected strain 13 guinea pigs suggest that this lipid mediator may play an important role in the development of cardiopulmonary disturbances.

Animals↗

PubMed1992

Acute ethanol administration and the metabolism of glutamine by skeletal muscle of the rat: implications for ethanol-induced reductions in protein synthesis.

The effect of acute ethanol administration (75 mmol/kg) on the metabolism of glutamine by skeletal muscle of the rat was studied in order to investigate the hypothesis that the concentration of this amino acid in muscle controls the rate of protein synthesis. Ethanol administration was without effect on the concentration of glutamine in EDL (extensor digitorum longus) and plantaris muscles (Type II fibre-rich muscles), but increased the concentration in soleus muscle (Type I fibre-rich muscle). The rate of release of glutamine was increased from EDL muscle, but unchanged from soleus muscle of treated animals. Ethanol administration was without effect on the maximal activity of glutamine synthetase in both soleus and EDL muscles. It is concluded that changes in the concentration of glutamine in muscle cannot explain the ethanol-induced changes in the rate of protein synthesis. Nevertheless, the increase in the concentration of glutamine in soleus muscle following ethanol administration is of interest and may be mediated via modulation of the glutamine transporter and/or the activity of glutamine synthetase in vivo.

Alanine↗

PubMed1992

[Lung function changes during pregnancy].

The lung functions in different pregnant stages were measured in 41 women with pregnancy and 12 normal women without pregnant. Forced Vital Capacity (FVC) was found gradually decreasing as pregnancy advanced (P less than 0.05). After 28 weeks of gestation, the Vital Capacity (VC), Forced Expired Volume in 1 second (FEV 1) significantly decreased as compared with the normal values (P less than 0.01 or P less than 0.05). These results suggested that the lung function changed gradually during pregnancy, especially after the 28th week, significantly in VC, FVC and FEV 1. Maybe there are slight obstructions in the bronchial tubes. After the 28th week of gestation and it may be the reason for occurrence of breathshort and the lung infection.

Adult↗