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Biomedical subjects

D Liang

Publications and source records attributed to D Liang.

108 records · Page 6Linked to original sources
PubMed1991

Ventricular function and contractile proteins in the infarcted overloaded rat heart.

STUDY OBJECTIVE: The aim was to determine whether surviving myocardium in the infarcted rat heart retains the ability to respond to sustained increases in afterload. DESIGN: Cardiac mass, ventricular function, and actomyosin ATPase activity were compared in animals subjected to coronary artery ligation to produce infarction, superimposed renal artery constriction 4 weeks after infarction, and in sham operated animals. EXPERIMENTAL MATERIAL: Female Wistar rats obtained at 10 weeks of age (200-225 g) were used for the studies. MEASUREMENTS AND MAIN RESULTS: Four weeks after coronary artery ligation, infarcted hearts showed a 22% increase in heart weight and a significant reduction in peak systolic pressure and +/- dP/dt during acute volume infusion and aortic occlusion compared to sham operated hearts. Eight weeks after the initial surgical intervention, the infarct group showed significant impairment in ventricular performance compared to the sham operated group but no further decrement was observed between hearts with infarction and those with infarct and superimposed renal artery constriction for peak systolic pressure and +/- dP/dt during volume infusion and aortic occlusion. Actomyosin ATPase activity, however, was depressed and the shift to V3 myosin isoenzyme was greater in infarct and renal artery constriction compared to infarct alone. CONCLUSIONS: Left ventricular myocardium following infarction does not retain the ability to increase cardiac mass and shows depressed levels of actomyosin ATPase activity when exposed to a superimposed chronic afterload from renal artery constriction. However, cardiac function in situ is maintained.

Animals↗
PubMed1991

[Determination of hydrocortisone and methylprednisolone in plasma by reversed-phase HPLC].

A sensitive and rapid method for the simultaneous measurement of both hydrocortisone (HC) and methylprednisolone (MP) using dexamethasone (DX) as the internal standard was presented. High-performance liquid chromatograph Model 344 (Beckman, USA) with a 254 nm wavelength UV detector and reversed-phase Ultrasphere ODS (5 microns) column was used. Sample was extracted with ethyl acetate and the organic layer was evaporated to dryness under an air stream in a 37 degrees C water bath. The residue was dissolved in 30 microliters mobile phase and 20 microliters injected. The mobile phase of methanol and 0.01 mol/L acetate buffer (pH 3.0) (64:36) was pumped at 1.0 ml/min through the column. The detector was operated at 0.005 aufs. The retention time for HC, MP and DX was 5.43 min, 7.7 min and 11.5 min, respectively. Standard curve was linear in the concentration range of 0.02 to 1.28 mg/L for HC and 0.05 to 12.8 mg/L for MP. Sensitivity was 1 ng for HC and 1.5 ng for MP; extraction recovery 76-83%; within day CV less than 4%, and inter-day CV less than 6% for both steroids.

Animals↗
PubMed1991

[An approach to correcting scoliosis. Mechanism and operative procedure].

In the treatment of scoliosis, we found that soft tissue contracture on the concave side is the main force maintaining deformity, resisting correction and rejecting implants. So the release of contracture would get rid of the bow-string effect of the contractured tissues from the main curve, such as the capsules and ligaments around costo-transverse joints, the inter-transverse and intercostal muscles, together with the posterior section of the corresponding ribs would also be taken off by those shrunken tissues close to the main curve, like the capsules and ligaments around the costo-vertebral joints. Since 1982, 23 patients aged 6 to 16 years were treated operatively. The operation was done in 2 stages: contracture release on the concave side and fusion with bone grafting on both side laminae through body cast. Follow up for 1 to 8.5 years showed satisfactory results. The mechanism and effect of soft tissue contracture of idiopathic and congenital scoliosis are discussed in detail.

Adolescent↗
PubMed1990

[The relationship between percutaneous rate of drug and its HPLC retention behavior].

A series of 13 p-aminobenzoate esters were selected as model drugs to study correlations between HPLC retention parameters and percutaneous rate. The octanol/water partition coefficient and solubility of these compounds were determined and their permeation through rat skin was measured using a Franz diffusion cell. Capacity factor and retention index were used as HPLC retention parameters and calculated from their retention times. The results indicate that for the p-aminobenzoate esters studied, the capacity factors and retention indices obtained in our experimental conditions are indicators of relative lipophilicity of drugs and can be used to predict their steady-state fluxes and permeation coefficients by using the Hansch equation. They are easy to obtain and reproducible enough to substitute for the more laborious and inaccurate partition coefficient values.

4-Aminobenzoic Acid↗
PubMed1989

A study of molecular epidemiology of adenovirus of types 3 and 7 on infant pneumonia in northern China.

This paper analysed 102 strains of adenovirus types 3(Ad3) and 7(Ad7) causing infant pneumonia from 1976 to 1988 in northern China. Two genotypes of Ad7, 7b and 7d, were identified by using restriction endonucleases, BamHI, BcLI, BgLI, SmaI, XbaI and HindIII. 3 genotypes of Ad3, 3I, 3II and 3III, were identified by using BgLII and BamHI. Of 56 Ad7 strains, 34 were 7b (76.8%) spread over last 10 years; 13 7d(23.2%) occurred from 1982, together with 7b. Of 46 Ad3 strains, 42 3I(91.3%) spread over the past 12 years. 3II and 3III scattered all over these years. Ad3I and Ad7b were the dominant genotypes. The results indicated that Ad7d tended to increase with time from 1982. It is possible that Ad7d will become dominant genotype and replace Ad7b.

Adenoviridae Infections↗
PubMed1988

Acetabuloplasty for congenital dislocation of the hip in children.

A modified acetabuloplasty, which has been employed at our hospital since 1977, is described for the treatment of congenital dislocation of the hip in children. The procedure has been performed on a total of 74 hips in 61 children (average age 6.7 years), with satisfactory results obtained in 87.8% of hips. The technique, its indications, and pre- and postoperative management are detailed. The procedure possesses the advantages of both the shelf and Pemberton procedures and has proved to be an effective operation for older children with poor acetabular development. Our results show that, when performed correctly, this procedure is simple, safe, and effective.

Acetabulum↗
PubMed1979

Clinical hepatotoxicity of isoniazid in children.

A patient is presented with reversible clinical and biochemical hepatocellular injury secondary to isoniazid (INH). This apparently rare drug reaction in children is compared with the more common transient hypertransaminasemia induced by isoniazid. A review of the clinical literature and basic pharmacologic mechanisms of isoniazid-induced hepatotoxicity has led to a rational plan for monitoring and managing children who are treated with INH.

Alanine Transaminase↗
PubMedDate not supplied

Alterations in synaptic transmission and plasticity in hippocampus by a complex PCB mixture, Aroclor 1254.

Developmental exposure to polychlorinated biphenyls (PCBs) has been associated with a variety of neurological effects including cognitive dysfunction. The present study assessed the effects of acute in vitro exposure to a complex mixture of highly chlorinated PCBs, Aroclor 1254 (A1254), on synaptic transmission in the hippocampus of the rat. Increases in population spike (PS) amplitude were observed in field potentials recorded from the pyramidal cell layer of CA1 in response to 1.0-3 microg/ml of A1254. PS amplitude was increased by approximately 20% 5-10 min following the beginning of exposure to 3 microg/ml A1254, with some recovery towards baseline amplitudes occurring by 30 min, despite continuous perfusion. Longer exposures revealed that a maintained 10% increase in PS amplitude persisted beyond 90 min of exposure to 3 microg/ml A1254. A second recording electrode in the stratum radiatum revealed modest increases in EPSP slope (approximately 10%) that were transient. EPSP slope changes appeared within 5 min of exposure to A1254 (3 microg/ml), peaked at 10 min, and declined to baseline levels by 30 min, despite continued perfusion with A1254. Monitoring over a protracted period revealed relatively stable EPSP slope amplitudes following the return to baseline levels. Long-term potentiation (LTP) is a model of synaptic plasticity believed to encompass the physiological substrates of memory. Neither magnitude or persistence of PS potentiation recorded from the stratum pyramidale was affected by 3 microg/ml A1254. LTP of the EPSP slope recorded in the stratum radiatum was also induced to a comparable degree in control and A1254-treated slices. However, the augmentation in the dendritic response was not maintained in the treated slices over the 60-min posttrain recording period. Acute effects of PCBs on calcium homeostasis, protein kinase C translocation, dopaminergic function, and hormonal action may contribute to the pattern of effects seen in synaptic transmission and plasticity in the hippocampus.

Animals↗