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Biomedical subjects

B Sun

Publications and source records attributed to B Sun.

At least 217 records · Page 12Linked to original sources
PubMed1996

Long-term cycling of surfactant films in Wilhelmy balance.

Surface properties of porcine surfactant were observed during long-term cycling in Wilhelmy balance. Various amounts of surfactant were applied onto the surface as dry particles or droplets, or were suspended in the hypophase, and the films generated by this material were subjected to 50% cyclic compression at a rate of 1 cycle per min. Film spreading was faster from a droplet than from a particle of lyophilized surfactant, but the "stable period" during which minimum surface tension of the compressed film remained below 5 mN/m was significantly longer for the dry material. For surfactant suspensions the period of film "refinement", defined as the number of cycles required to reduce minimum surface tension to a level below 5 mN/m, was inversely correlated with the concentration of surfactant in the hypophase. Thirteen batches of porcine surfactant, used successfully in clinical trials for treatment of neonatal respiratory distress syndrome, were evaluated in the same system suspended in the hypophase at a concentration of 0.5 mg/ml. Films adsorbed from these batches had a median refinement period of 4 cycles, and a median stable period of 2160 cycles (36 h). In the same assay system, surfactant activity was inhibited in a dose-dependent manner by serum, fibrinogen, meconium, and bilirubin, but the specific inhibitory activity was significantly higher for bilirubin than for the other substances tested.

Analysis of Variance↗
PubMed1996

Elevated levels of plasminogen activator inhibitor-1 may account for the altered fibrinolysis by keloid fibroblasts.

Using a 3-dimensional fibrin gel model system simulating fibroplasia of wound repair, we investigated the interaction between keloid fibroblasts and fibrin matrix and compared it with that of normal fibroblasts. Normal skin fibroblasts caused fibrin gel degradation under serum-free conditions, whereas keloid fibroblasts did not cause microscopically detectable gel degradation. Fibrin gel degradation occurred through plasmin-mediated fibrinolysis, which was initiated by fibroblasts exhibited high uPA but low plasminogen activator inhibitor-1 (PAI-1) activities, and transforming growth factor-beta 1 prevented fibrinolysis of normal fibroblasts by upregulating PAI-1 while downregulating uPA activities. In contrast, keloid fibroblasts exhibited an intrinsically high level of PAI-1 and a low level of uPA. This change in the ratio of activator and inhibitor activities was attributed to altered fibrin degradation by keloid fibroblasts. The PAI-1 increase was also demonstrated at the RNA level by Northern analysis. In terms of the pivotal role of the plasmin/plasminogen activator system in matrix remodeling, the elevated PAI-1 level exhibited by keloid fibroblasts may have significant consequences not only in altered fibrin degradation, but also in subsequent repair steps that lead to keloids and fibrosis.

Fibrin↗
PubMed1996

Effect of Hoe 694, a novel Na(+)-H+ exchange inhibitor, on intracellular pH regulation in the guinea-pig ventricular myocyte.

1. Hoe 694 (3-methylsulphonyl-4-piperidinobenzoyl, guanidine hydrochloride) is a Na+/H+ exchange (NHE) inhibitor exhibiting cardioprotective properties during ischaemia and reperfusion in animal hearts. We have (i) tested the selectivity of Hoe 694 for NHE over other pHi-regulating mechanisms in the myocardium, and (ii) tested if the functionally important NHE isoform contributing to intracellular pH regulation in heart is NHE-1, as suggested from molecular biology studies of this protein. 2. pHi was recorded by fluorescence microscopy with carboxy SNARF-1, AM-loaded into single ventricular myocytes of guinea-pig. 3. In nominally HCO3-free media, recovery of pHi from an intracellular acid load is mediated by NHE, and was inhibited by Hoe 694, amiloride (an NHE inhibitor) or dimethyl amiloride (DMA, a high affinity NHE inhibitor) with potency values of 2.05, 87.3 and 1.96 microM respectively, giving the potency series: Hoe 694 congruent to DMA > > amiloride. This potency series, and the potency values (corrected for drug competition with extracellular Na+) match those determined previously for cloned NHE-1 expressed in mutant fibroblasts. In the absence of extracellular Na+ (to inhibit NHE), Hoe 694 had no effect on pHi. 4. In 5% CO2/HCO3(-)-buffered solution containing DMA, pHi recovery from acidosis is mediated by Na(+)-HCO3- symport and was unaffected by Hoe 694. The drug also had no effect on pHi recovery from an alkali-load, a process largely mediated by Cl(-)-HCO3- exchange. Finally, the fall of pHi upon adding extracellular Na-lactate is assisted by H(+)-lactate symport, and this too was unaffected by Hoe 694. 5. We conclude (i) Hoe 694 has no detectable inhibitory potency for pH-regulating carriers in heart other than NHE. (ii) native NHE functioning during pHi-regulation in the cardiomyocyte is the NHE-1 isoform. These data strengthen the case for NHE-1 being the receptor for mediating the cardioprotective effects of Hoe 694.

Amiloride↗
PubMed1996

Antibody to surfactant protein A increases sensitivity of pulmonary surfactant to inactivation by fibrinogen in vivo.

It has been suggested that surfactant protein-A (SP-A) protects surfactant activity from inhibitors such as fibrinogen. Substantial evidence indicates that inhibition of surfactant activity is often important in the pathogenesis of acute respiratory failure. Studies on surfactant function in the pulsating bubble surfactometer imply that SP-A helps to maintain low surface tension in the presence of inhibitors such as fibrinogen. We tested whether SP-A acts in this way in vivo. Rabbit pups, 29 d gestational age, were treated with a monoclonal antibody to rabbit SP-A (R5) followed by fibrinogen, or with control preparations (normal IgG and saline, respectively). Lung compliance was measured during ventilation throughout these experiments. Air-space volume and pulmonary edema were quantitated morphometrically. Animals receiving anti-SP-A antibody + fibrinogen showed substantial and significant impairment in lung compliance compared with control littermates receiving normal IgG and/or saline. Lungs from these animals showed decreased pulmonary air-space volume and increased alveolar edema. We conclude that SP-A protects pulmonary surfactant from inhibition by fibrinogen in vivo. This protective activity may be important in the pathogenesis of both adult and neonatal respiratory distress syndromes, and it may also be useful in devising therapies for these diseases.

Animals↗
PubMed1996

Exogenous surfactant improves ventilation efficiency and alveolar expansion in rats with meconium aspiration.

The pathogenesis of neonatal meconium aspiration syndrome (MAS) may involve inactivation of endogenous surfactant, and data from clinical pilot studies indicate that treatment with exogenous surfactant may alleviate respiratory failure in babies with MAS. We studied ventilation efficiency after treatment with a modified porcine surfactant in experimental meconium aspiration. Adult rats were anesthetized and tracheotomized, and received via a tracheal cannula from 4 to 6 ml/kg body weight of a saline suspension of human meconium (25 mg [dry weight]/ml). After 30 min of ventilation with 100% oxygen, the animals were in respiratory failure, with dynamic lung-thorax compliance < 0.5 ml/cm H2O/kg and PaO2 < 8 kPa (60 mm Hg). Animals were then allocated to: (1) immediate treatment with surfactant (200 mg/kg); (2) treatment with surfactant (200 mg/kg 3 h later; or (3) a control group not receiving surfactant. All animals were ventilated for 6 h with variable FIO2 and peak inspiratory/positive end-expiratory pressure (PIP/PEEP). In the control group, six of 12 animals died of respiratory failure with hypoxemia and acidosis despite ventilation with 100% oxygen and high mean airway pressure (> 20 cm H2O). The lungs of all animals in this group showed severe atelectasis, influx of neutrophils, edema, and hyaline membranes. In contrast, animals allocated to immediate or late surfactant treatment had lower mortality (one of seven and two of eight, respectively), a reduction of oxygen supply by 30%, and a decrease in mean airway pressure of 3 to 4 cm H2O. This was associated with a > 50% increase in static lung volume at 40 cm H2O inflation and 10 cm H2O deflation pressure and improved alveolar expansion in histologic sections. Hyaline membranes tended to be less prominent in surfactant-treated animals than in controls. We conclude that both early and late treatment with surfactant is effective in this animal model of MAS.

Animals↗
PubMed1996

Use of surfactant in pulmonary disorders in full-term infants.

Pulmonary surfactant is routinely used for treatment of premature babies with respiratory distress syndrome, and its use in full-term infants with respiratory failure is now under extensive clinical investigation. Several clinical reports have shown that intratracheal instillation of large doses of bovine and porcine lung-derived surfactant preparations has the potential to improve blood oxygenation and ventilation efficiency in full-term neonates with respiratory distress syndrome, meconium aspiration syndrome, pneumonia, pulmonary hemorrhage, and lung hypoplasia. These findings are suggestive of secondary surfactant deficiency or surfactant dysfunction in the pathogenesis of respiratory failure in full-term infants. Further clinical investigation with multicenter, randomized, controlled clinical trials is warranted to verify new indications of surfactant application for these diseases.

Extracorporeal Membrane Oxygenation↗
PubMed1996

Effects of enflurane and isoflurane anesthesia on the pharmacokinetics of pancuronium in adult patients.

OBJECTIVE: To evaluate the effects of 1 MAC of enflurane or isoflurane anesthesia on the pharmacokinetics of pancuronium. METHODS: Eighteen adult patients undergoing the elective plastic surgery were randomly divided equally into 3 groups, namely, Group 1 (control group), Group 2 (enflurane group) and Group 3 (isoflurane group). Anesthesia was maintained with thiopental and 67% N2O-O2 in Group 1, 1 MAC enflurane in Group 2 and 1 MAC isoflurane in Group 3. After administration of a bolus of pancuronium 100 micrograms/kg, an improved fluorimetric assay was used to determine the serum concentrations of pancuronium and the pharmacokinetic variables of pancuronium were calculated with a 3P87 program. RESULTS: The disposition of pancuronium may be well described mathematically by a two-compartment open model. The results showed that in comparison with the control group, patients in Group 2 and Group 3 had a longer T1/2 beta and MRT. The patients in Group 2 had the slower K10 and lower CL than those in the control group. There were no significant differences among the three groups in T1/2 alpha, V1, V2, Vdss, V beta, K21, K12 and AUC. CONCLUSION: During enflurane and isoflurane anesthesia, CL of pancuronium decreased, and T1/2 beta and MRT of pancuronium were prolonged in our patients, so duration of the effective plasma concentrations of pancuronium was much longer. As a result, the effects of enflurane and isoflurane of the pharmacokinetics of pancuronium may be part of reason why two drugs extended the duration of neuromuscular depression produced by pancuronium.

Adolescent↗
PubMed1996

[Limbal epithelial autograft transplantation for treatment of unilateral fibrous vascularized cornea caused by chemical burns].

OBJECTIVE: To provide healthy epithelial source for damaged cornea to prevent the invasion of conjunctival tissue for treatment of corneal vascularized opacity after chemical turns. METHODS: Limbal epithelial autograft transplantation was performed on 17 cases (17 eyes) with vascularized corneal opacity caused by chemical burns. RESULTS: Of 17 cases, the epithelial healing was stable in 15 cases, and there was corneal graft transparency, improvement of visual acuity and without neovascularization in 13 cases. CONCLUSION: Limbal epithelial autograft Limbal epithelial autograft transplantation applied for reconstruction of palisades of Vogt to provide new stem cell source for injured limbus is a reasonable therapeutic method for treatment of vascularized corneal opacity caused by chemical burns.

Adolescent↗
PubMed1996

Premature aging in persons with Down syndrome: MR findings.

PURPOSE: To determine whether persons with Down syndrome have features of premature aging on routine MR imaging sequences. METHODS: Sixty MR studies (in 30 persons with Down syndrome and 30 age- and sex-matched control subjects) were reviewed retrospectively by two blinded examiners. Sagittal T1-weighted and axial T2-weighted spin-echo images were evaluated for the presence and severity of three markers of brain aging: atrophy, white matter lesions, and T2 hypointensity of the basal ganglia, referenced to the examiner's internal standard of normal for that age and sex. RESULTS: Persons with Down syndrome had higher prevalence and severity of the three markers studied than the control subjects. Atrophy and white matter lesions increased in prevalence with age; abnormal T2 hypointensity of the basal ganglia was more equally distributed with age. CONCLUSION: Persons with Down syndrome have features of premature aging detectable at routine MR imaging.

Adult↗
PubMed1996

[Studies on inhibition of activated oncogene expression by antisense RNA].

In this paper, the sense and antisense mammalian expression vectors of T24-ras activated oncogene were introduced into cultured NIH3T3 cells in sense-->antisense and antisense-->sense orders. The transfected cells were selected by drug selection. The morphology change, Southern hybridization, frequency of soft agar colonies and the detection of P21 amount were investigated. The results showed that the sense recombinant could cause the malignant transformation of NIH3T3 cells while the antisense recombinant could inhibit this kind of transformation. Furthermore, the inhibitory effect varied according to the different transfected orders.

3T3 Cells↗
PubMed1996

[The pharmacokinetics of pancuronium bromide in infants, children and adults].

Twenty-four patients scheduled for elective plastic surgery were selected to study the pharmacokinetics of pancuronium bromide under enflurane anesthesia. The patients were divided into three groups by their ages; Group 1 consisted of 5 infants (0.75-2.95 years); Group 2 contained 13 children (4-14 years); Group 3 included 6 adults (16-27 years). An improved fluorimetric assay was used to measure the plasma concentrations of pancuronium bromide after administration of pancuronium bromide at a dose of 100 micrograms/kg. The results showed that the disposition of pancuronium bromide may be best described mathematically by a two-compartment open model in all patients. The younger the patients, the larger the distribution volumes and the higher the Cl. There were significant differences among the three groups with regard to V1, V2, Vdss, Cl, AUC. The T1/2 beta and MRT were longer in Group 1 than in Group 2 and Group 3.

Adolescent↗
PubMed1996

[Effect of tetrandrine on intraacinar pulmonary arterial structural remodelling and pulmonary hypertension].

Rat's pulmonary hypertension was induced by a single subcutaneous injection of monocrotaline. The influences of tetrandrine (Tet) upon the structure of intraacinar pulmonary arteries (IAPA) was studied by light and electron microscopy. The results indicated that Tet reduced the thickness of IAPA medial membrane, the ratio of the thickness of IAPA medial membrane to the diameter of IAPA, the number of circular muscular artery and partially muscular artery about 16.4%, 30.5%, 24.3% and 16.4% respectively, and Tet increased the number of nonmuscular artery about 24.7%. It also decreased the degeneration of IAPA, collagen of medial membrane, prolife-ration and myoid differentiation of the pericyte, and it increased the number of IAPA. The authors discussed why Tet caused such changes.

Alkaloids↗
PubMed1996

[In situ observation of the relationship between apoptosis and proliferation in large bowel carcinoma and its precancerous lesion].

OBJECTIVE: To investigate action of apoptosis in tumorigenesis by observation of the relationship between apoptosis and proliferation. METHOD: Using terminal deoxynucleotidyl transferase-mediated dUTP niok end labelling (TUNEL) technique, PCNA immunohistochemical staining, and HE staining, we observed the density and distribution of apoptotic cells, proliferating cells and mitotic cells in situ in 15 normal mucosa, 32 villous adenoma and 33 papilloid adenocarcinoma of large bowel. RESULTS: The zone of apoptotic cells located in superficies and zone of proliferating cells in base in normal mucosa. These characteristics of distribution were lost in villous adenomas and papilloid adenocarcinomas of large bowel. The density of apoptotic cells in villous adenomas was significantly higher than that in normal mucosa and carcinomas. The density of apoptotic cells lowered and the density of proliferating cells rose in villous adenomas. Comparison of villous adenoma with papilloid adenocarcinoma, showed that apoptotic cells decreased and proliferating cells increased significantly. CONCLUSIONS: Through selectivity, the cells have highly proliferative ability prodominanted, resulting in malignant transformation. This phenomenon was named as a selective proliferation of cells.

Adenocarcinoma, Papillary↗
PubMed1996

[Suppressive effect of corticosteroids on the gene expression of interleukin-5 and eosinophil activation in asthmatics].

Although cortico steroids are effective anti-inflammatory agents in ameliorating asthma symptoms and bronchial hperreactivity, their mechanism of action is unknown. Interleukin (IL)-5 is known to play a key role in regulating eosinophil proliferation and activation. Therefore, we examined the changes of IL-5 mRNA expressions in PBMC semi-quantitatively with RT-PCR as well as serum ECP levels and MCH-PC20 values in asthmatics before and after being treated with corticosteroids. The results revealed that there were significant decrease in the level of IL-5 mRNA and serum ECP concentration after therapy (P < 0.05) and there was remarkable improvement in the values of MCH-PC20 and FEV1% (P < 0.05). It was also found that the changes of serum ECP levels or MCH-PC20 values were accompanied by a reduction in IL-5 mRNA expression (r = 0.5426 or 0.4857, P < 0.05). These results suggested that the therapeutic effects of corticosteroids in asthma may result from modulation of IL-5 gene expression with consequent inhibition of eosinophil activation.

Adult↗
PubMed1996

[Infarcts of rostral basilar artery territories clinicoradiological evaluation].

34 cases with infarcts of rostral basilar territory arteries, including posterior cerebral artery (PCA), rostral basilar artery (BA) and superior cerebellar artery (SCA) confirmed by CT and MRI were reported. The clinical manifestations might be divided into 3 groups according to the supplying artery: the cortical branch of PCA (21 cases), the perforated branch of PCA (22 cases) and the SCA (10 cases). However, combination was often seen. MRI is superior than CT in finding lesions of this region. The use of digital substraction angiograph, magnetic resonance angiography and transcranial Doppler in defining the site of vascular occlusion was discussed.

Adult↗
PubMed1996

[Change of tumor necrosis factor and interleukin-6 in brochoalveolar lavage fluid of allergic asthma].

OBJECTIVES: To explain the change of TNF-alpha, IL-6 biological activity in supernatant of cultured AM and in BALF in the athmatic animal. METHOD: The guinea pig model of asthma was established by frestly immunizing and then challenging the animal with 1% ovalbumin; The level of TNF-alpha and IL-6 were measured by L929 cytotoxic test and by the MH60. BSF2 cell proliferation test. RESULTS: TNF-alpha and IL-6 in BALF and supernatant of AM in asthmatic animals were increased significantly, and there was a strong correlation between TNF-alpha and IL-6. CONCLUSIONS: TNF-alpha and IL-6 might play a key role in the allergic airway inflamination and AM might be the source of TNF-alpha and IL-6.

Animals↗
PubMed1996

239 cases of high fever in viral upper respiratory infection (URI) treated with xiang shi qing jie (XSQJ) bag tea.

XSQJ bag tea was used to treat 239 cases of high fever caused by viral upper respiratory infection, widely spreading in summer and autumn. For comparison, a control group treated by penicillin combined with Ganmao Qingre Chongji or Banlangen Chongji was set up. The results showed the effect of XSQJ bag tea on the time of abating fever, resolving symptoms and physical signs were significantly better than that of the control group.

Adenovirus Infections, Human↗