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Biomedical subjects

L Fu

Publications and source records attributed to L Fu.

At least 127 records · Page 7Linked to original sources
PubMed1995

Platelet-activating factor mediates the ozone-induced increase in airway microvascular leakage in guinea pigs.

In the present study, we asked whether platelet-activating factor (PAF) mediates the ozone-induced increase in airway microvascular leakage. To answer this question, we examined the effect of a PAF receptor antagonist on the ozone-induced increase in airway microvascular leakage quantified by the extravasation of Evans blue dye in the guinea pig trachea and main bronchi. Guinea pigs were pretreated with the PAF receptor antagonist, E6123 ((S)-(+)-6-(2-chlorophenyl)-3-cyclopropane-carbonyl-8,11-dimethyl-2,3,4, 5- tetrahydro-8H-pyrido[4',3':4,5]thieno[3,2- f][1,2,4]triazolo[4,3-a][1,4]diazepine) (0.01, 0.1 and 1.0 mg/kg i.v.) and then exposed to 3 ppm ozone for 30 min. The PAF receptor antagonist significantly reduced the ozone-induced increase in microvascular leakage in a dose-dependent manner in both the trachea and main bronchi. Our results indicate that PAF mediates the ozone-induced increase in airway microvascular leakage. We therefore suggest that PAF may be involved in ozone-induced airway inflammation.

Animals↗
PubMed1995

Molecular defects in Krabbe disease.

Krabbe disease (globoid cell leukodystrophy) is an autosomal recessive neurodegenerative disorder that affects both the central and peripheral nervous systems due to an enzymatic defect of the galactocerebrosidase. In this study, molecular defects in Krabbe disease were investigated in 11 patients (seven Japanese and four non-Japanese) using cultured skin fibroblasts. A Japanese late infantile patient had a missense mutation of Pro at codon 302 to Ala and a non-Japanese patient had a missense mutation of Val at codon 550 to Gly. The reduced enzymatic activities expressed from the cDNAs with these missense mutations and from the previously reported nonsense mutation (E369X, Glu at codon 369 to stop codon) were confirmed. Genomic DNA analyses revealed that the P302A and E369X mutations were heterozygous and the V550G mutation was homozygous in these patients. A 12 base deletion with a 3 base insertion was found in three unrelated Japanese infantile patients, but not in 30 controls. The mutation was homozygous in two patients and heterozygous in one patient. We could not find any confirmed mutation in the coding region in the other six patients. These findings suggest that mutations in infantile and late infantile patients are relatively heterogeneous.

Amino Acid Sequence↗
PubMed1995

The posttranslational modification of phosphoglucomutase is regulated by galactose induction and glucose repression in Saccharomyces cerevisiae.

The enzyme phosphoglucomutase functions at a key point in carbohydrate metabolism. In this paper, we show that the synthesis of the major isoform of yeast phosphoglucomutase, encoded by the GAL5 (PGM2) gene, is regulated in a manner that is distinct from that previously described for other enzymes involved in galactose metabolism in the yeast Saccharomyces cerevisiae. Accumulation of this isoform increased four- to sixfold when the culture experienced either glucose depletion or heat shock. However, heat shock induction did not occur unless the cells were under glucose repression. This nonadditive increase in expression suggests that the regulatory mechanisms controlling the heat shock induction and glucose repression of the GAL5 gene are functionally related. We previously demonstrated that phosphoglucomutase is modified by a posttranslational Glc-phosphorylation reaction. We now show that this posttranslational modification, like phosphoglucomutase expression itself, is also regulated by galactose induction and glucose repression. Finally, no evidence was found to indicate that the Glc-phosphorylation of phosphoglucomutase alters its enzymatic activity under the conditions examined.

Base Sequence↗
PubMed1995

[Identification on the botanical origin of xueshangyizhihao produced in Shaanxi, Gansu, Sichuan Provinces and Ningxia Hui Autonomous Region].

The botanical origin of Xueshangyizhihao should be Aconitum brachypodum var. laxiflorum produced in Dongchuan, Huize and Xundian districts in Yunnan Province. Recently, this herb has been found coming from Shaanxi, Gansu, Sichuan Provinces and Ningxia Hui Autonomous Region. Botanical identification show that except the one from Sichuan being of the same origin as that from Yunnan, this herb consists essentially of the species of genus Aconitum, mainly A. flavum, A. pendulum, and others such as A. sungpanense, A. polyschistum and A. iudlowii.

China↗
PubMed1995

[The effect of renal dopamtne receptor blockade on natriuresis induced by volume expansion and intracerebroventricular injection of hypertonic saline in rabbits].

The present study was carried out to study the effects of renal dopamine receptor blockade on natriuresis induced by volume expansion (VE) and intracerebroventricular injection of hypertonic saline (ICHNa) in connexion with the use of dopamine receptor blockers haloperidol (Hal) in anesthetized rabbits. In the VE experiments, Hal group decreases the peak increase of UNa V from control group of 65.0 +/- 15.0 to 19.0 +/- 5.5 mumol/min (P < 0.02). In the ICHNa experiments, the peak increase of UNa V in control and Hal groups were respectively 28.9 +/- 4.6 and 29.0 +/- 5.8 mumol/min (P > 0.50). In the experiments of rabbit with intact renal dopamine receptor, the natriuresis induced by VE+ICHNa was significantly greater than those due to either inducing factor acting alone. Renal dopamine receptor blockade also significantly attenuated the natriuresis induced by VE+ICHNa. These results indicate that renal dopamine receptor blockade significantly attenuated the natriuresis induced by VE or VE+ICHNa, but did not affect the response of ICHNa. In the rabbits with intact renal dopamine receptor, the natriuretic response induced by VE+ICHNa was significantly greater than those response by either inducing factor acting alone.

Animals↗
PubMed1994

Polygenic trait analysis by neural network learning.

AI techniques have been applied to the domain of DNA sequence analysis in predicting or identifying certain specialized regions, in recognizing genes, and in understanding the evolutionary relationships between sequences. This paper focuses on a kind of genetic pattern recognition, namely, the problem of identifying the gene combinations (patterns) causally related to a given trait determined by multiple genes (a so-called polygenic trait). A novel approach is presented which combines neural-network and knowledge-based techniques. The neural network is trained to predict the trait and then the knowledge embedded in the network is decoded into symbolic patterns. This hybrid approach is evaluated in the domain of identifying genes of insulin dependent diabetes mellitus. The consistency between the results with this approach and those reported in genetic literature supports the viability of this approach.

Artificial Intelligence↗
PubMed1994

Capsaicin reduces ozone-induced airway inflammation in guinea pigs.

We investigated whether neural pathways are involved in mediating ozone (O3)-induced airway inflammation. To determine this, we studied the contribution of adrenergic and cholinergic pathways to the O3-induced increase in airway vascular permeability, an indicator of airway inflammation, by measuring vascular permeability after giving guinea pigs propranolol or atropine to block these pathways. We also studied the contribution to O3-induced airway inflammation of neuropeptides localized in unmyelinated airway sensory nerves, by measuring vascular permeability after giving capsaicin to deplete neuropeptides from these nerves. We found that capsaicin reduced but did not abolish the increase in airway vascular permeability induced by 3 ppm O3 for 30 min. Propranolol and atropine had no effect on airway vascular permeability. These results indicate that neuropeptides released from sensory nerves, presumably by acting through the axon reflex, partly mediate O3-induced airway inflammation, and that adrenergic and cholinergic pathways are not involved.

Analysis of Variance↗
PubMed1994

[Changes in serum lipoprotein cholesterol in rabbit model of calcium bilirubinate cholangiolithiasis].

The lithogenic process of cholangiolithasis is still not understood clearly. In this study, several serum lipoprotein cholesterol, the bile BA level, etc. in the rabbit model of calcium bilirubinate cholangiolithiasis was examined. The main results included: (1) The concentrations of HDL-ch and HDL2-ch in the serum decreased in all the experimental groups (P < 0.01; P < 0.05), except HDL-ch in the BO 1W group (P > 0.05) compared with the control group. The concentrations of HDL2-ch in the BOI 1W and the BOI 6W groups were lower than those in the BO 1W and the BO 6W groups respectively (P < 0.05); the both concentrations of Fch and HDL3-ch in the BOI and the BO groups were much higher than those in the control group (P < 0.01). (2) The bile T-BA level was lower in the both BOI groups than that in the control group (P < 0.05). It began to decrease in the BO group during the first week, but it was not significant in statistical difference (P > 0.05). During the 6th week the level of the bile acid (BA) was much lower than that in the control group (P < 0.05). According to the above results, it may be concluded that in the formation of calcium bilirubinate gallstones, caused by the biliary obstruction and infection, there is a disorder in the lipoprotein metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Vaccination of bovines against Schistosomiasis japonica with cryopreserved-irradiated and freeze-thaw schistosomula.

Four laboratory tests and one field trial with cryopreserved irradiated (CI) schistosomula vaccine and a freeze-thaw (F/T) vaccine against bovine Schistosomiasis japonica were carried out in 1979 and 1980 with the following results: (1) Single intradermal vaccination in buffalo calves each with 10,000 20 krad CI Schistosomula plus 1 ml BCG gave 62% worm reduction (P < 0.05). Using the same protocol 55% worm reduction (P < 0.01) was obtained in cattle. (2) Buffalo calves immunized twice, at a 1.5 month interval, with 10,000 and 20,000 CI schistosomula, respectively, resulted in a worm reduction 65%. (3) In a preliminary field trial with 10,000 CI schistosomula plus 1 ml BCG resulted in a worm reduction of 53% in buffalo calves. (4) Intradermal vaccination of 30,000 F/T schistosomula with 1 ml BCG was also tried in cattle and revealed a worm reduction of 57% but increasing the number of vaccinations did not improve the protective effect. (5) Evidence regarding the effects of immunization with CI vaccine in buffaloes and F/T vaccine in cattle, on the number of eggs and miracidia and that of female worms themselves was obtained. (6) Immune responses, cellular and humoral, elicited in buffaloes vaccinated with CI schistosomula were detected by means of Lymphocyte Transformation Assay and Enzyme Linked Immunosorbent Assay.

Animals↗
PubMed1993

Induction and the possible mechanism of ventricular tachycardia after catheter ablation with direct current shocks in dogs.

Cathodal DC shocks (150-J) were administered via the His bundle to 20 closed-chest dogs, and in a further three dogs 25-J cathodal shocks were given via the left ventricular endocardium. In 18 dogs, including three that underwent left ventricular ablation, Holter electrocardiograms were recorded from 1 to 7 days after ablation, and 4 weeks after ablation. There were frequent episodes of sustained ventricular tachycardia (VT) from the first few hours after ablation to 4 days after ablation in all dogs, but both the rate and the coupling interval of VT were variable. In five conscious dogs stimulated 1 day after ablation, it was difficult to induce and terminate VT repeatedly. There was a direct relationship between the paced cycle length and the interval of the last paced beat to the initiating VT beat in three out of four dogs. In the fourth dog there was an inverse relationship. There was no transient entrainment with ventricular burst pacing during VT in any of the four dogs tested. The effects of lidocaine (2-3 mg.kg-1), verapamil (0.2-0.4 mg.kg-1), and propranolol (0.2 mg.kg-1) on VT were tested within 2 days of ablation in 10 conscious dogs. In general, both lidocaine and verapamil terminated VT, and propranolol slowed VT. In conclusion, VT soon after ablation possibly results from triggered activity, although abnormal automaticity cannot be ruled out.

Animals↗
PubMed1993

Postreceptor events involved in the up-regulation of beta-adrenergic receptor mediated lipolysis by testosterone in rat white adipocytes.

In the previous studies we have shown that testosterone increases lipolytic responsiveness to catecholamines in rat white adipocytes, and that is associated with an up-regulation of beta-adrenergic receptor density. However, the postreceptor events involved in the testosterone induced enhancement of beta-adrenergic receptor activated lipolysis in these cells have not been adequately studied, and were therefore investigated in the present study. Male Sprague Dawley rats were divided into three groups: control, castrated, and castrated treated with testosterone. The beta-adrenergic receptor-mediated cAMP accumulation, measured with RIA after isoproterenol (a beta-adrenergic agonist) stimulation was decreased in castrated rats, and reversed by testosterone treatment, suggesting a testosterone effect at or proximal to adenylate cyclase. However, no differences between the groups were found in abundance of G alpha protein messenger RNAs (G alpha s, G alpha i-1, and G alpha i-2) as analyzed by Northern blot and a solution hybridization RNase protection assay, or in G protein mass measured with a quantitative enzyme-linked immunosorbent assay in fat cell membrane preparation. Lipolysis stimulated by N6-monobutyryl-cAMP was reduced in castrated rats and recovered by testosterone treatment, suggesting that components distal to the adenylate cyclase, i.e. protein kinase A (PKA) and/or hormone sensitive lipase (HSL) also are involved in testosterone regulation of lipolysis. In conclusion, these and previous results suggest that the testosterone-induced increase in lipolytic response to catecholamines in rat white adipocytes is mediated through several events including an increased beta-adrenergic receptor density, probably an increased adenylate cyclase activity and an increased protein kinase A/hormone sensitive lipase activity at the postreceptor level with apparent absence of effect on the expression of G-proteins.

Adenylyl Cyclases↗