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Biomedical subjects

D Jiang

Publications and source records attributed to D Jiang.

176 records · Page 10Linked to original sources
PubMed1991

Nonlinear algorithm for identification of a fiducial marker for various cardiac events.

We report on a nonlinear algorithm which identifies R-wave peaks on the surface electrocardiogram, consistent reference points on the left ventricular pressure waveform and the initiation of the QRS complex on the epicardial electrogram. The algorithm has been used to evaluate data from horses, ponies, dogs and humans at rest and during exercise. It permits rapid, accurate evaluation of data on a beat-by-beat basis even with noisy signals and varying waveform configurations. The algorithm facilitates the acquisition of detailed information previously difficult or impossible to obtain by more conventional methods of analysis.

Algorithms↗
PubMed1991

[Effect of 6-hydroxydopamine on cerebral catecholamines, lipid peroxidation and antioxidant enzymes in rats-concerned with pathogenesis of Parkinson's disease].

As an animal model of human Parkinson's disease 250 micrograms of 6-Hydroxydopamine was injected intraventricularly in the rats. At 24 h, 48 h, 7th and 14th day after injection, the levels of dopamine, norepinephrine, Cu, Zn- and Mn- superoxide dismutase (SOD), catalase as well as the lipid peroxidative products in the striatum, midbrain and hypothalamus were determined. Our data showed that catecholamines decreased persistently, catalase and Mn-SOD decreased concomitantly, Cu, Zn-SOD, however, remained, unchanged. Lipid peroxidative products increased shortly after injection, then subsided. Our result suggests that lipid peroxidation might be involved in the degenerative process of neurons in Parkinson's disease.

Animals↗
PubMed1991

Digital signal analysis of cardiac events in horses and ponies.

We have developed a digital signal analysis technique which can be used to evaluate various cardiac events in ponies and horses at rest and during exercise. The algorithm is designed to identify R-wave peaks on the surface electrocardiogram, consistent reference points on the left ventricular pressure waveform and the initiation of the QRS complex on the epicardial electrogram. We have used the technique to evaluate data from 10 horses and ponies at rest, during strenuous exercise and during experimentally-induced coronary artery occlusion. The technique provided rapid and accurate beat-by-beat evaluation of data, even with relatively noisy signals and under conditions in which the waveform configurations were not consistent. The benefits afforded by this technique make it especially useful for extracting information which previously was difficult or impossible to obtain using more conventional methods of analysis.

Algorithms↗
PubMed1990

In vivo immune selection of a Moloney murine leukemia virus-induced tumor results in the loss of viral- but not tumor-associated antigens.

A protocol of in vivo immune selection has been used to isolate a variant of the Moloney murine leukemia virus (MuLV)-induced tumor MBL-2. Characterization of the tumor variant indicated that selection resulted in the isolation of a cell which is incapable of producing infectious virus and no longer capable of synthesizing viral proteins. Although the failure to express viral Ag has rendered the variant tumor cells resistant to lysis by CTL specific for MuLV viral Ag, the variant tumor cells retained their susceptibility to lysis by CTL which appear to be directed against an MuLV-induced tumor-associated Ag. The data indicate that the expression of nonviral tumor-associated Ag by MBL-2 is not dependent upon continued viral gene expression.

Animals↗
PubMed1990

Spontaneous improvement after acute ischemic stroke. A pilot study.

Recent clinical studies emphasize the importance of early (less than 12 hours after onset) treatment of patients with acute ischemic stroke. Therapies have been proposed as being effective because of early clinical improvement. The frequency and degree of spontaneous improvement in such patients, however, is unknown. We prospectively evaluated the course of 29 patients (19 men, 10 women) aged 33-82 years who were seen less than or equal to 12 hours after the onset of acute ischemic stroke. Seventeen patients were first evaluated less than or equal to 6 hours and the remaining patients at 6-12 hours after onset. All patients were examined using a modified National Institutes of Health Stroke Scale at baseline, 1, 2, 3, and 6 hours. No specific treatment for acute ischemic stroke was given during this time. Improvement (defined as a decrease of greater than or equal to 2 points from baseline score) was noted at 1 hour in seven patients (24%). By 6 hours 15 patients (52%) had improved, 12 (41%) were unchanged, and two (7%) were worse. Our results suggest that spontaneous, often dramatic improvement occurs in patients with acute ischemic stroke and should be taken into consideration in the design of any trial of acute treatment.

Adult↗
PubMed1990

[The measurement of radial bone mineral content in children].

The bone mineral contents of radius of 255 boys and 243 girls (7 to 16 year old of the Han nationality, living in Chengdu) were measured with Bone Mineral Analyzer (Type:SPA-I). The standard values of g/cm was made. There was a positive correlation between the value in boys or girls and chronological age, height or weight. The coefficients were respectively 0.83, 0.77, 0.64 in boys and 0.82, 0.82, 0.82 in girls (P less than 0.005). At the age of 13 (in boys or in girls) the value of the g/cm was the highest.

Adolescent↗
PubMed1983

Normal erythrocyte uptake of L-DOPA in Parkinson's, Huntington's, and related diseases.

We measured the kinetic constants for the unidirectional influx of L-DOPA into red blood cells of patients with Parkinson's disease (seven patients), Huntington's disease (seven patients), and other extrapyramidal diseases (11 patients), and in five controls. Influx consisted of two components with low affinity and high exchange capacity. In individual subjects, the L-DOPA concentration giving half-maximal influx (Km) varied between 0.04 and 2.19 mM, and the maximum velocity (Vmax) of the saturable transport component was between 20 and 578 mumol/l cell water/h, which is compatible with the neutral amino acids of low affinity for the transport system. The range of Kd (the first-order rate constant for the unsaturable component) was between 0.11 and 0.36 hour-1. There was no gross deficit of the L-DOPA uptake process in patients with Parkinson's disease, Huntington's disease, dystonia, or other extrapyramidal diseases.

Biological Transport↗
PubMed1982

Effect of 3',4'-dihydroxy-2-methyl-propriophenone (U-0521) on catechol-O-methyltransferase activity and on DOPA accumulation in rat red blood cells and corpus striatum.

The effects of the catechol-O-methyltransferase (COMT) inhibitor 3',4'-dihydroxy-2-methyl-propriophenone (U-0521) were studied in red blood cells (RBC) and corpus striatum in the rat. In vitro U-0521 inhibited RBC COMT activity in a dose-dependent manner with an IC50 of 6 x 10(-6)M. In vivo maximum inhibition (90%) of enzyme activity in RBC was obtained with 250 mg/kg with a peak effect at 5 min and enzyme recovery within 90 min. In U-0521-pretreated rats L-3,4-dihydroxyphenylalanine (L-DOPA) accumulation in RBC and corpus striatum, after injection of L-DOPA, was significantly higher than in nonpretreated rats. The use of COMT inhibitor along with L-DOPA may be of benefit in the treatment of Parkinson's disease.

Animals↗
PubMed1982

The effect of chronic L-dopa administration on supersensitive pre- and postsynaptic dopaminergic receptors in rat brain.

Chronic administration of haloperidol induced supersensitivity of the pre- and postsynaptic dopaminergic receptors in rat brain. The response of the presynaptic receptors was determined by an enhanced inhibitory effect of apomorphine on dopamine synthesis after gamma-butyrolactone injection. This change in the receptor function was detected both in the nigrostriatal and mesolimbic pathways. Haloperidol also increased the 3H-spiperone binding sites in striatal membranes, indicating supersensitivity of the postsynaptic receptors. Subsequent prolonged treatment with high doses of L-DOPA/carbidopa resulted in a decrease in 3H-spiperone binding sites, but had no effect on the supersensitive presynaptic receptors. It is suggested that tardive dyskinesia may be a state of both pre- and postsynaptic dopamine receptor supersensitivity and that chronic L-DOPA treatment may have a differential effect on these sites.

Animals↗
PubMed1982

Catechol-O-methyltransferase inhibition by U-0521 increases striatal utilization of levodopa.

The effects of U-0521, a catechol-O-methyltransferase (COMT) inhibitor, were studied on this enzyme activity and on Dopa metabolism in rat striatum. In vivo maximal inhibition (95%) of COMT activity was obtained at 5 min with enzyme recovery to 64% of basal activity at 120 min. When injected in increasing doses U-0521 (200 mg . kg-1) inhibited, at 10 min, COMT activity by 85% with an IC50 = 80 mg . kg-1. In rats pretreated with U-0521 and then with DOPA the accumulation of 3-O-methyldopa-(OMD) in the plasma was essentially blocked while Dopa, dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) accumulation in the striatum was significantly higher than in DOPA treated controls. U-0521, a potent COMT inhibitor, enhances the availability and utilization of levodopa in the brain and may thus be helpful in future treatment of parkinsonian patients.

Animals↗
PubMedDate not supplied

Neurotensin interacts with dopaminergic neurons in rat brain.

Neurotensin (NT) injected intracerebroventricularly in rat increases dopamine (DA) turnover in the corpus striatum and nucleus accumbens. Significant increases in 3,4-dihydroxyphenylacetic acid (DOPAC) levels occurred within 15 minutes after injection with peak levels at 60 minutes. The effect on NT on DOPAC and homovanillic acid (HVA) accumulation was dose-dependent at 3-100 micrograms. NT, like haloperidol, stimulated 3,4-dihydroxyphenylalanine (DOPA) accumulation in striatal neurons, in the presence of DOPA decarboxylase inhibitor, after injection of gamma-butyrolactone (GBL). NT had a similar stimulatory effect on DOPA levels in the accumbens while haloperidol (0.25 mg.kg-1) had no significant effect in this brain region. NT did not block the inhibitory effect of apomorphine on DOPA accumulation in both the striatum and accumbens, while haloperidol inhibited apomorphine effect in both regions. NT also failed to displace 3H-spiperone from DA receptors and the presence of NT in the binding assay did not alter the ability of DA to displace 3H-spiperone in either brain region. These experiments demonstrate that NT increases DA turnover in both the nigrostriatal and mesolimbic pathways.

3,4-Dihydroxyphenylacetic Acid↗
PubMedDate not supplied

Anti-endothelial cell antibodies in Behçet's disease.

OBJECTIVE: Circulating antibodies that bind to human endothelial cells cultured in vitro have been detected in a variety of diseases, including Behçet's disease. In this disorder the reported prevalence of AECA has varied widely. One likely source of variability is the ELISA assay itself, in which differing conditions and reagents have been used in different reports. METHODS: We have re-examined the frequency of AECA in 132 Turkish Behçet's patients and 50 healthy Turkish controls, comparing several different methods of preparing the target endothelial cells. Human umbilical vein endothelial cells (HUVEC) were used either: 1) fresh and non-treated, 2) fixed, or 3) TNF alpha-stimulated. All stages of the procedures were performed at room temperature. RESULTS: In Behçet's patients, using fresh, non-treated HUVEC, 17 of 130 (13.1%) and 9 of 132 (6.8%) sera were positive for IgG- and IgM-AECA, respectively. However, among 50 normal controls, 2 (4.0%) had IgG-positive and 4 (8.0%) had IgM-positive ELISAs under the same conditions. The difference in the frequency of positives between patients and controls was not statistically significant. Fixed HUVEC and TNF alpha-treated HUVEC gave similar results as well. When group means were examined, only the mean for IgG-AECA determined with TNF alpha-stimulated HUVEC reached statistical significance. CONCLUSION: The discrepancy between our data and earlier reports in the literature probably reflects the methodological differences alluded to, and highlights the difficulties in interpreting ELISA assays for AECA.

Adult↗