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Biomedical subjects

F Y Liu

Publications and source records attributed to F Y Liu.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Effects on simvastatin in continuous ambulatory peritoneal dialysis patients with hyperlipidemia].

The therapeutic effects of simvastatin on hyperlipidemia and its protective effects on residual renal function (RRF) in continuous ambulatory peritoneal dialysis (CAPD) patients with hyperlipidemia were observed. Forty-seven CAPD patients were randomly divided into two groups, the treatment group and control group. The treatments of two groups were the same except that the treatment group patients were additionally given simvastatin 20 mg.d-1. The results were that, after 12-week treatment, the total cholesterol (TC), triglyceride (TG), low density lipoprotein (LDL), and apoprotein B100 (ApoB100) in the treatment group significantly decreased, but high density lipoprotein (HDL) and apoprotein A1 (ApoA1) significantly increased compared with the control group (all P < 0.05); one year later, RRF of patients of both groups all decreased but there was no significant difference between them. The results suggest that simvastatin can effectively normalize lipidemia, but has no protective effect on RRF in CAPD patients.

Adult↗
PubMed2000

["Bu-yang huanwu tang" inhibited the pathogentic process of atherosclerosis induced by cholesterol-rich diet in rabbits].

BACKGROUND AND OBJECTIVE: "Bu-yang huanwu tang", a decoction of Chinese herbs widely used in the treatment for cardio- and cerebro-vascular diseases, has been demonstrated to be able to inhibit platelet adhesion and aggregation, to lower blood lipids, to regulate vascular tone from animal experiments. The aim of this study is to determine whether this decoction inhibits the pathogentic process of atherosclerosis induced by cholesterol-rich diet in rabbits. METHODS: Three groups of rabbits received the following different diets for 9 weeks: 1. standard diet; 2. atherogenic diet(standard diet plus 1% cholesterol and 3.3% fat); 3. atherogenic diet plus this decoction(5 g.kg-1.d-1). Plasma lipids, 6-keto-PGF1 alpha, endothelin levels were detected and the histological atherosclerotic changes were evaluated. RESULTS: This decoction inhibited the progression of aortic and abdominal aortic intimal plaques and reduced aortic intimal thickening. CONCLUSION: The anti-atherogenic mechanism might be related to the decrease of plasma cholesterol and triglycerides and the increase of PGI2. The facts suggest that "Bu-yang huanwu tang" has antiatherogenic and antithrombotic effects.

Animals↗
PubMed2000

Nephrotoxicity of high- and low-osmolar contrast media. The protective role of amlodipine in a rat model.

PURPOSE: To evaluate the nephrotoxicity of high- and low-osmolar contrast media (HOCM, LOCM) on kidneys in Sprague-Dawley rats. The protective role of amlodipine was studied. MATERIAL AND METHODS: Forty rats of both sexes were randomly divided into 5 groups (n=8/group) and glycerine for inducing renal failure was given to all rats except controls. RESULTS: In diatrizoate-injected rats, blood urea nitrogen (BUN) and serum creatinine (SCr) were increased; levels of phospholipase A2 (PLA2), lipid peroxide (LPO) and calcium were also increased in renal tissues. There was no significant difference between LOCM (iohexol) animals and glycerol controls either in the renal levels of PLA2, LPO and calcium or in the levels of BUN and SCr. The histologic changes were milder in the LOCM animals than in the HOCM animals. In the group pretreated with amlodipine, no increase in the levels of BUN or SCr was discovered and the renal content of PLA2, LPO and calcium were significantly lower than in the HOCM group; the renal injuries induced by diatrizoate were alleviated. CONCLUSION: The HOCM, diatrizoate, was more toxic to rat kidneys than the LOCM iohexol; PLA2, LPO and calcium load played a role in producing renal function impairment induced by diatrizoate meglumine; amlodipine protected the renal tissue from nephrotoxicity induced by diatrizoate.

Acute Kidney Injury↗
PubMed2000

[Revision of the biological significance of the contact system].

Current concept of blood coagulation is divided into two stages: an "initiation" stage which is handled by tissue factor pathway, and an "augmentation" stage handled by intrinsic pathway beginning in factor XI. Recent studies have demonstrated that the contact system is a modulator for vascular biology with vascular tone regulation, anticoagulant, profibrinolytic, antiadhesive and proinflammatory functions. Changes of contact system are associated with sepsis, thrombosis, etc.

Animals↗
PubMed2000

[Application of capillary chromatography in benzene boiling range analysis].

The experimental data were analyzed by regression analytical method and the relation between the quantity of impurities and the boiling range of benzene was demonstrated. It was proved that when the quantity of hydrocarbon impurities was within certain limits, the quality of benzene fractions can be determined by analyzing the hydrocarbon impurities in it. So the distillation method for analyzing benzene boiling range may be replaced by capillary chromatography for analyzing the hydrocarbon impurities. The practical applications support the above suggestion.

English Abstract↗
PubMed1999

Assessment of renal function in the early stages of nephrotoxicity induced by iodinated contrast media.

To determine whether there are early renal function parameters (RFP) which can be monitored to rapidly detect nephrotoxicity induced by contrast media (CM), we observed RFP in 16 patients with normal renal function before and after administration of CM. Forty-eight hours after diatrizoate meglumine administration, blood urea nitrogen (BUN) and serum creatinine (SCr) increased (p < 0.05). In all patients, acute tubular damage was revealed by early urinary RFP. Increases in levels of serum angiotensin-I-converting enzyme (ACE), beta(2)-microglobulin (beta(2)M) and urinary albumin (Alb) were associated with alterations in glomerular function. The changes in early RFP occurred earlier than those of BUN and SCr. The present study demonstrates that serum ACE, beta(2)M, urinary Alb, gamma-glutamyl-transpeptidase and N-acetyl-beta-D-glucosidase are sensitive parameters for the early assessment of subclinical nephrotoxicity induced by CM.

Adolescent↗
PubMed1999

Assessment of urinary endothelin-1 and nitric oxide levels and their relationship with clinical and pathologic types in primary glomerulonephritis.

To determine the relationship between the urinary endothelin (ET-1), nitric oxide (NO) levels and the clinical, pathologic types of primary glomerulonephritis (GN) patients, urinary levels of ET-1 and NO were detected in 27 patients with biopsy-proven primary GN and 12 normal controls by radioimmunoassay and by copper-plated and cadmium column reduction assay, respectively. The results showed that urinary ET-1 levels in the patients with primary GN were significantly higher than in normal controls (p < 0.01), while the urinary ET-1 levels in patients with moderate mesangial proliferation GN were significantly higher than those in patients with mild mesangial proliferation GN (p < 0.05). Urinary ET-1 levels in patients whose clinical feature was nephrotic syndrome were found to be higher than in patients whose clinical feature was nephritic syndrome. However, urinary NO levels were to the contrary (p < 0.05). The ratio of ET-1/NO in primary GN patients was significantly higher than that in normal controls, and it positively correlated with the 24-hour urinary excretion of protein. These results suggest that urinary ET-1 levels are related to the proliferation of mesangial cells. The imbalance between ET-1 and NO may be related to the pathogenesis of primary GN and the occurrence of proteinuria.

Adolescent↗
PubMed1998

Effects of vitamin C on myocardial mitochondrial function and ATP content in hypoxic rats.

AIM: To observe the effects of large dose of vitamin C (Vc) on myocardial mitochondrial function, ATP content, and myocardial structure in acute and chronic hypoxic rats. METHODS: Rats were exposed to a simulated altitude 4000 m (barometric pressure = 43 kPa) for 3 and 30 d. Vc (0.75 g.kg-1.d-1) was injected i.p. The heart mitochondrial respiratory function were determined by Clark-type O2 electrode; mitochondrial membrane fluidity (MMF) were assayed through fluorescence polarizative method; the contents of ATP, ADP, and AMP in myocardial tissue were measured with HPLC. RESULTS: After administration of Vc, the ATP content was increased from 35 +/- 3 mg.g-1 to 53 +/- 3 mg.g-1 in acute hypoxic rats (P < 0.01), from 42 +/- 4 mg.g-1 to 48 +/- 3 mg.g-1 in chronic hypoxic rats (P < 0.01); Pa, O2 was increased from 7.2 +/- 1.4 kPa to 9.5 +/- 1.2 kPa in acute hypoxic rats (P < 0.01); mitochondrial respiratory control rate (RCR) was increased from 2.1 +/- 0.6 to 4.7 +/- 0.5 in acute hypoxic rats (P < 0.01), and from 3.3 +/- 0.7 to 4.5 +/- 0.6 in chronic hypoxic rats (P < 0.01); MMF was increased in acute and chronic hypoxic rats (P < 0.05); the degree of myocardial necrosis in vitamin C preventive rats was attenuated as compared with those of acute hypoxic rats. CONCLUSION: Vc is effective on improving myocardial energy metabolism and protecting against myocardial structural injury in hypoxic rats.

Adenosine Triphosphate↗
PubMed1998

[Heat shock response induces resistance to hydrogen peroxide and increases synthesis of interleukin-6 in rat astrocyte in vitro].

Cell viability and cell membrane disruption of rat astrocyte after heat shock response (HSR) were assessed by the analysis of MTT reduction and lactate dehydrogenase (LDH) release. We studied whether HSR would modulate the susceptibility of astrocyte to H2O2-induced oxidative stress. Cell viability was assessed by reduction of MTT. HSR in 43 degrees C water bath for 30 min decreased H2O2 toxicity (P < 0.01) to astrocyte. HSR induced decrease in H2O2 (50 mumol/L) toxicity was also shown by the reduction in the release of LDH, which was a marker of cell membrane disruption. The result also showed that prior to the incubation in 43 degrees C water bath for 30 min strongly increased IL-6 release 6 h (P < 0.05) after HSR. The above data suggest that the enhanced release of IL-6 from astrocyte may be one of the mechanisms underlying the cell protective effect induced by HSR.

Animals↗
PubMed1998

False-positive 2-[F-18]-fluoro-2-deoxy-D-glucose positron emission tomography studies for evaluation of focal pulmonary abnormalities.

Positron emission tomography (PET) with 2-[F-18]-fluoro-2-deoxy-D-glucose (FDG) can demonstrate the glucose metabolism characteristics of a lesion, which may be helpful in differentiating between benign and malignant focal pulmonary lesions. Malignant cells demonstrate higher glucose metabolic activity than benign lesions. However, some inflammatory processes also show significant FDG uptake. We present two cases where high FDG uptake was found in inflammatory lesions in the lungs. The first case was that of a 38-year-old woman with chronic cough for more than 20 years. FDG PET revealed a hypermetabolic lesion with a lesion-to-background ratio of 8.0 at the posterior aspect of the right middle lung. She underwent thoracotomy and tumor resection, and was diagnosed with cryptococcosis. The second case was that of a 72-year-old woman who had pulmonary tuberculosis previously with cavitation in the left lower lobe. She suffered from fever, chills and severe hemoptysis for several days before this admission. FDG PET revealed a hypermetabolic ring at the periphery of the cavity. The lesion-to-background ratio was 7.8. Echo-guided biopsy showed no evidence of malignancy. She was treated with antibiotics and the symptoms subsided gradually. Lung abscess complicating a pre-existing cavity was diagnosed. These two cases substantiate that positive FDG PET results should be interpreted with caution in differentiating benign from malignant pulmonary abnormalities, especially in regions with a high prevalence of granulomatous lesions.

Adult↗
PubMed1996

In vitro-in vivo relationship of oral extended-release dosage forms.

PURPOSE: A method to establish the in vitro-in vivo relationship of oral extended-release products is proposed. METHODS: The approach utilizes incremental amounts of drug released and absorbed within defined time intervals, to construct a chi2 distributed variable for testing in vitro-in vivo similarity. RESULTS: A case study is used to demonstrate that the similarities between incremental values of in vivo absorbed and in vivo dissolved fractions are distinguishable for different dissolution profiles despite naturally significant linear correlations between cumulative in vivo absorbed and in vitro dissolved fractions (with different dissolution tests) of an oral extended-release product. CONCLUSIONS: The method enables investigators to compare different in vitro dissolution profiles of an oral extended-release product to find an optimized dissolution profile to be the surrogate of the in vivo release process of the product.

Absorption↗
PubMed1996

Preventive and therapeutic effects of nitrendipine on hypoxic right ventricular hypertrophy.

AIM: To assess whether nitrendipine (Nit) can be used to prevent and treat the hypoxic right ventricular hypertrophy (RVH). METHODS: Rats were exposed to a simulated altitude of 5000 m (barometric pressure = 54 kPa) for 30-60 d. Nit (10-20 mg.kg-1.d-1) was administered via gavage. The therapeutic efficacy was evaluated with right ventricular weight index (RVWI), right ventricular systolic pressure (RVSP), and myocardial ultrastructure. RESULTS: Chronic intermittent hypoxia for 30 d (8 h.d-1) resulted in an increase of RVSP and RVWI as well as in the changes of RV myocardial ultrastructure. As the hypoxic time was prolonged to 60 d, RVWI and RVSP were not further augmented. Nit (20 mg.kg-1.d-1, i.g.), when administered from the beginning of hypoxia, reduced RVSP (8.1 +/- 1.1 vs 6.0 +/- 1.0 kPa, P < 0.05) and RVWI (1.014 +/- 0.012 vs 0.915 +/- 0.049 mg/g body weight, P < 0.05). After development of hypoxic RVH, Nit (20 mg.kg-1) also decreased RVSP (7.9 +/- 1.0 vs 6.2 +/- 0.8 kPa, P < 0.05) and RVWI (1.02 +/- 0.13 vs 0.88 +/- 0.12 g/kg body weight, P < 0.05). Myocardial blood flow was increased and myocardial ultrastructure became nearly normal in rats treated with Nit. CONCLUSION: Nit prevented and lessened the hypoxic right ventricular hypertrophy.

Animals↗
PubMed1995

Pharmacokinetics of oral extended-release dosage forms. I. Release kinetics, concentration, and absorbed fraction.

In this study, we derive pharmacokinetic models for oral extended-release (OER) drug products with defined in vivo release kinetics (IVRK) and a compartmental system. Fitting the model to clinical data, we were able to examine the correlation between released and absorbed fractions. Furthermore, we found that absorbed fractions of OER products can be expressed by absorption rate and release duration only. The expression is unchanged in different compartmental systems with the same IVRK, implying that the IVRK drives the pharmacokinetic system of an OER product. The apparent absorption rate constant of an OER product can be estimated by solving an implicit equation using observed concentrations. We also propose a new method for calculating absorbed fractions, which is more accurate than Loo-Riegelman method. Ultimately, these methods may permit optimally designed OER products.

Absorption↗
PubMed1993

Cerebellar stimulation modulates thalamic noxious-evoked responses.

Parafascicular (PF) neurons responding to noxious stimuli and focal electrical stimulation of midbrain, diencephalon, and hypothalamic nuclei, which send projections to PF, modulates the PF spontaneous and noxious-evoked responses. Some cerebellar efferents ascend to PF. This investigation attempted to study the effect of cerebellar stimulation on spontaneous and noxious-evoked PF neuronal activity in rats. It was observed that 26% (73/280) of PF neurons responded to a noxious stimulus. The PF neuronal population exhibits two cell types according to their response pattern following the noxious stimulus. One type of PF neurons were excited (n = 53) and were classified as nociceptive-on cells. The second type of PF neurons responded to noxious stimulus by a decrease in the ongoing firing rate (n = 20) and were classified as nociceptive-off cells. The responses of these two types of nociceptively identified cells were tested following cerebellar lateral nucleus stimulation (Lat.N.S.) utilizing several current intensities. Lat.N.S. with lower intensities (0.1-0.2 mA) elicited suppression of both spontaneous and nociceptive-evoked discharges of the nociceptive-on neurons, although higher intensities (0.4-0.6 mA) elicited excitation on both discharges of this type of neuron. In contrast, Lat.N.S. induced a monophasic intensity-dependent suppression of both the spontaneous and the nociceptive-evoked discharges of the nociceptive-off neurons. The results indicate that Lat.N.S. modulates the nociceptive-evoked responses of PF neurons. The possible role and related pathways of cerebellum in modulating noxious input were discussed.

Animals↗
PubMed1993

Pulmonary delivery of free and liposomal insulin.

The effects of oligomerization and liposomal entrapment on pulmonary insulin absorption were investigated in rats using an intratracheal instillation method. The results indicated that both dimeric and hexameric insulins can be rapidly absorbed into the systemic circulation, producing a significant hypoglycemic response. Intratracheal instillation of insulin in two different oligomerized states has not resulted in any significant difference in the duration of hypoglycemic effect. However, the initial hypoglycemic response (first 10 min) obtained from intratracheal administration of 25 IU/kg hexameric insulin appears to be slower than that from the 25 IU/kg dimeric insulin, thereby suggesting that hexameric insulin may have a lower permeability coefficient across alveolar epithelium than the dimeric insulin. Intratracheal administration of insulin liposomes (dipalmitoylphosphatidyl choline:cholesterol, 7:2) led to facilitated pulmonary uptake of insulin and enhanced the hypoglycemic effect. Nevertheless, similar insulin uptake and pharmacodynamic response were obtained from both the physical mixture of insulin and blank liposomes and liposomally entrapped insulin.

Animals↗
PubMed1992

Pulmonary biotransformation of insulin in rat and rabbit.

In vitro biodegradation of insulin in rabbit and rat lung homogenates was investigated. Insulin can be sequentially metabolized into two primary fragments in rabbit lung homogenate by an aminopeptidase. The amino acid sequences of the fragments were found to be the des-Phe-InsulinB1 (Metabolite I) and des-Phe-Val-InsulinB1-2 (Metabolite II). However, only the former metabolite (Metabolite I) was identified in the rat lung homogenate. The km and Vm values associated with rabbit lung homogenate were 0.29 +/- 0.14 mM and 16.4 +/- 6.9 microM/hr/mg protein, respectively, whereas those for a rabbit lung preparation containing both microsomes and cytosol were 0.22 +/- 0.07 mM and 17.9 +/- 5.4 microM/hr/mg protein, respectively. The km and Vm associated with the cytosolic fraction of rabbit lung were 0.32 +/- 0.16 and 20.6 +/- 6.1 microM/hr/mg protein, respectively. The results indicate that the lung aminopeptidase may be a cytosolic enzyme. The degradation of dimeric insulin in the lung homogenate was faster than that of hexameric insulin due to the difference in collision frequency between the enzyme and insulin aggregates. The major metabolites in the lungs reportedly retain almost the same bioactivity of insulin, suggesting that the pulmonary route of insulin delivery will not adversely affect its hypoglycemic activity.

Animals↗