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Biomedical subjects

J Liang

Publications and source records attributed to J Liang.

At least 181 records · Page 10Linked to original sources
PubMed1997

Central vasopressin is required for the complete development of deoxycorticosterone-salt hypertension in rats with hereditary diabetes insipidus.

It has been shown that vasopressin receptors are upregulated in the brain and that the central vasopressin pathway is involved in the development of deoxycorticosterone acetate (DOCA)-salt hypertension. However, it is unclear whether central vasopressin, in itself, is essential for this type of hypertension. To clarify this issue, the effect of centrally administered vasopressin on the development of DOCA-salt hypertension was studied in homozygous Brattleboro rats which genetically lack vasopressin. In homozygous Brattleboro rats, treatment with intracerebroventricular infusion of vasopressin (1 ng/h) alone or DOCA-salt (weekly subcutaneous injection of 30 mg/kg deoxycorticosterone acetate and 0.3% NaCl to drink) alone had no effect on systolic blood pressure (SBP). On the other hand, hypertension was partially restored in homozygous Brattleboro rats treated with intracerebroventricular infusion of vasopressin and DOCA-salt (SBP: 175 +/- 4 mmHg), although the magnitude of elevation of SBP was one-third of that in Long Evans rats treated with DOCA-salt (278 +/- 15 mmHg). These hypertensive homozygous Brattleboro rats showed an increase in fluid intake and urinary sodium excretion, as observed in DOCA-salt hypertensive Long Evans rats. These results suggest that central vasopressin is required for the complete development of DOCA-salt hypertension and the mechanism is, in part, due to enhanced sodium intake through the additive effect of central vasopressin and DOCA-salt.

Animals↗
PubMed1997

Observations on the treatment of natural haemosporidia infections by total alkaloid of Peganum harmala L. in cattle.

Eighty two cattle naturally infected with haemosporidians were treated with total alkaloid hydrochloride of Peganum harmale L. (0.5 mg/kg/day). Fifty eight cases with Theileria sergenti showed a cure rate of 86%; thirteen cases with Theileria annulata showed a cure rate of 85%; eight cattle infected with Babesia bigemina showed a cure rate of 88% and three cases of Anaplasma marginale were completely cured. The results suggested that the curative effect of total alkaloid of P. harmale was better than that of diminazene aceturate and produced minimal side effects. The alkaloid could also be administered to pregnant animals. It was concluded that the total alkaloid of P. harmale showed a marked effect as a treatment for haemosporidican infections in cattle.

Alkaloids↗
PubMed1997

Effect of total alkaloid of Peganum harmala L. in the treatment of experimental haemosporidian infections in cattle.

Cattle experimentally infected with Babesia bigemina or Theileria sergenti or mixed infestations of the two parasites were treated with Total Alkaloid of Peganum harmala L. The results showed that treatment was effective against B. bigemina infection, had a marked effect on the course of infection with T. sergenti and some effect on the course of the mixed infection.

Alkaloids↗
PubMed1997

Expression of foreign gene in mycobacterium regulated by human Mycobacterium tuberculosis heat shock protein 70 promoter.

The DNA fragments of 150bp length promoter of human Mycobacterium (M.) tuberculosis heat shock protein (hsp) 70 and 650bp length foreign gene, the Schistosoma japonicum glutathione S-transferase (Sj26GST) gene, were obtained by amplification with polymerase chain reaction. And the 150bp DNA sequence upstream initiation codon ATG of the human M. tuberculosis hsp 70 promoter that contains the sequence TTGAG and ATCATA which consensus with E. coli promoter's -35 and -10 region respectively, as well as ribosome binding site GGAGG at position -12--8 upstream the ATG were determined by SangerDideoxyribonucleotide-mediated chain-termination method. Then, the human M. tuberculosis hsp70 promoter and Sj26GST cDNA were cloned into E. coli-mycobacteria shuttle plasmid pBCG- 2000 to construct E. coli-Mycobacterium expression shuttle plasmid pBCG- Sj26 that can express Sj26GST gene. The M. smegmatis were electroporated and the positivecolonies were selected by kanamycin. The M. smegmatis containing the vector pBCG-Sj26 can be induced by heating and hydrogen peroxide (H2O2) to express GST. The molecular weight of the recombinant GST (rGST) was 26,000. The rGST contents that were about 10 percent of the total bacterial protein were analyzed by density scanning after running SDS-PAGE. This study would provide scientific evidences for application of hsp70 promoter in expressing foreign gene in mycobacterium and development of mycobacterium as multiple-valent vectoral vaccine.

Animals↗
PubMed1997

Computation of molecular electrostatics with boundary element methods.

In continuum approaches to molecular electrostatics, the boundary element method (BEM) can provide accurate solutions to the Poisson-Boltzmann equation. However, the numerical aspects of this method pose significant problems. We describe our approach, applying an alpha shape-based method to generate a high-quality mesh, which represents the shape and topology of the molecule precisely. We also describe an analytical method for mapping points from the planar mesh to their exact locations on the surface of the molecule. We demonstrate that derivative boundary integral formulation has numerical advantages over the nonderivative formulation: the well-conditioned influence matrix can be maintained without deterioration of the condition number when the number of the mesh elements scales up. Singular integrand kernels are characteristics of the BEM. Their accurate integration is an important issue. We describe variable transformations that allow accurate numerical integration. The latter is the only plausible integral evaluation method when using curve-shaped boundary elements.

Biophysical Phenomena↗
PubMed1997

Proliferating cells in the primary spongiosa express osteoblastic phenotype in vitro.

We have shown that intermittent parathyroid hormone (PTH) treatment targets proliferating cells in the primary spongiosa of trabecular bone of young rats, resulting in an increased number of osteoblasts. To further characterize these proliferating osteoprogenitor cells, bromodeoxyuridine (BrdUrd) incorporated in vivo, was used as a marker to identify and isolate cells for in vitro studies. Proliferating cells were labeled in vivo in young rats with BrdUrd and 24 h later were isolated by trypsinization of sections of the primary spongiosa of the distal femur metaphysis. Within 12 h of isolation, BrdUrd+ cells formed distinct foci containing 20-500 cells with fibroblast morphology. Stimulation of proliferation as determined by [3H]-thymidine incorporation was observed for these cells in response to fetal bovine serum, platelet derived growth factor, and transforming growth factor beta-1. Neither insulin-like growth factor-1 (IGF-1) nor insulin stimulated proliferation PTH (1-34) and dexamethasone inhibited proliferation. The effects of PTH and dexamethasone were additive. Cells expressed the osteoblast phenotype as evidenced by synthesis of type I collagen, expression of high alkaline phosphatase activity, and production of increased intracellular cAMP in response to PTH (1-34). Confluent cell aggregates spontaneously formed mineralized nodules within 4-7 days, in the absence of inducers. These observations suggest that the primary spongiosa cells recapitulates the differentiation process in vitro in an accelerated fashion and may serve as a useful model to study osteoblast differentiation.

Animals↗
PubMed1997

What can be measured from surface electrogastrography. Computer simulations.

The aims of this study were to investigate the detectability of the propagation of the gastric slow wave from the cutaneous electrogastrogram (EGG) and the patterns of the EGG when the gastric slow waves are uncoupled. A mathematical model was established based on the volume conductor theory to simulate the transfer of the serosal gastric slow wave from the stomach to the abdominal surface. A number of computer simulations were conducted using the model, and the periodic cross-correlation function was used to estimate the phase shift between the four channels. It was found that the propagation of the gastric slow wave was detectable from the multichannel EGG signals. The detectability of the propagation was, however, associated with a number of factors, such as the thickness of the abdominal wall and the propagation velocity of the serosal slow wave. The amplitude of the EGG was found to be associated with the coupling/uncoupling and propagation velocity of the gastric slow wave. The amplitude of the EGG increased when the propagation velocity of the gastric slow wave increased. The amplitude of the EGG was substantially decreased when the gastric slow waves were uncoupled. The uncoupling of the gastric slow wave at a frequency of 3 cpm produced dysrhythmias in the EGG, including tachygastria, bradygastria, and arrhythmia. The power spectra of simulated different positional EGG signals showed similar patterns when the gastric slow wave was coupled and different and unpredictable patterns when the gastric slow wave was uncoupled. In conclusion, multichannel EGG recordings may be necessary to obtain more information on gastric slow waves from the abdominal electrodes. The propagation and coupling or uncoupling of the gastric slow wave may be detected from multichannel EGG recordings.

Computer Simulation↗
PubMed1997

Enhanced expression of cytokine-induced neutrophil chemoattractant in rat hepatic allografts during acute rejection.

The kinetics of messenger RNA (mRNA) and protein levels of cytokine-induced neutrophil chemoattractant (CINC) in rat hepatic allografts during acute rejection were investigated. Infiltrating cells were identified by double immunostaining with anti-CINC and anti-macrophage monoclonal antibodies, ED1 and ED2. The serum CINC concentration in untreated hepatic allograft recipients increased significantly at a constant rate over time after transplantation. No significant increases in serum CINC concentrations were observed in hepatic isografts or allografts treated with the immunosuppressant FK506. The number of neutrophils in untreated hepatic allografts increased significantly at a constant rate. Conversely, neutrophil accumulation in isografts or allografts treated with FK506 was much less than in untreated hepaticallografts. Immunostaining revealed that in the portal areas, mononuclear cells infiltrating untreated allograft liver were mainly positive for CINC and that CINC+ cells represented a subpopulation (approximately 25%) of the ED1+ cells. On the other hand, in the sinusoidal areas CINC+ cells were scattered and mainly positive for ED2. Levels of CINC mRNA in liver tissues taken from untreated hepatic allografts increased after transplantation, peaked on day 5, and decreased thereafter. Hepatic allografts treated with FK506 or isografts showed much lower levels of CINC mRNA than untreated allografts. Allogeneic mixed lymphocyte reactions induced CINC production. The cellular source of CINC was mononuclear cells. CINC production in mixed lymphocyte reactions was inhibited in the presence of anti-tumor necrosis factor alpha (TNF-alpha) antibody. These results suggest that enhanced expression of CINC mRNA and prominent accumulation of neutrophils in the liver grafts are characteristic features of the immune response during acute rejection.

Animals↗
PubMed1997

Transitions in chronic low back pain in Japanese older adults: a sociomedical perspective.

This study examines the patterns and determinants of chronic low back pain over a three-year period among older adults in Japan. We tested our model based on a sociomedical perspective, using a two-wave national probability sample survey of persons aged 60 and older (N = 2,200) conducted in 1987 and 1990 in Japan. At baseline, the prevalence of chronic low back pain was 18 percent. Among those who were free of back pain at baseline, the probabilities of onset, death, and nonresponse were 13 percent, 7 percent, and 10 percent. Among those who had back pain at baseline, the probabilities of recovery, death, and nonresponse were 43 percent, 8 percent, and 9 percent, respectively. Our multinomial logistic regression analysis supports our thesis that societal factors (age, gender, education, and social relationships) affect transitions in chronic back pain not only directly, but also indirectly through mediating health and health behavior factors. The results suggest that social relationships have both favorable and unfavorable effects on chronic low back pain.

Aged↗
PubMed1997

Heel reconstruction.

From 1987 through 1990 we used the compound flap formed by the lateral leg flap, the fibula, and its surrounding soft tissues, pedicled on the distal peroneal vessels, to reconstruct heel and calcaneus defect in two patients. Both were successful and functionally good.

Adolescent↗
PubMed1997

Patterns of gastric myoelectrical activity in human subjects of different ages.

The aim of this study was to investigate the developmental change of gastric myoelectrical activity in humans. Five groups of healthy subjects were studied, including 10 preterm newborns, 8 full-term newborns, 8 full-term infants (ages 2-6 mo), 9 children (ages 4-11 yr), and 9 adults. Gastric myoelectrical activity was recorded using surface electrogastrography for 30 min before and 30 min after a test meal in each subject. Spectral analysis methods were applied to compute the parameters of the electrogastrogram (EGG). The results showed that the percentage of 2- to-4-cycles/min (cpm) slow waves was 26.6 +/- 3.9% in the preterm newborns, 30.0 +/- 4.0% in full-term newborns, 70 +/- 6.1% in 2- to 6-mo-old infants (P < 0.001 compared with newborns), 84.6 +/- 3.2% in 4- to 11-yr-old children (P < 0.03 compared with infants), and 88.9 +/- 2.2% in the adults (P > 0.05 compared with children). In conclusion, gastric slow waves are absent at birth, and there is a maturing process after birth. Age-matched controls are necessary for the interpretation of EGG data from neonates and infants, whereas EGG data in children are the same as in adults.

Adult↗
PubMed1997

Aberrations and retinal image quality of the normal human eye.

We have constructed a wave-front sensor to measure the irregular as well as the classical aberrations of the eye, providing a more complete description of the eye's aberrations than has previously been possible. We show that the wave-front sensor provides repeatable and accurate measurements of the eye's wave aberration. The modulation transfer function of the eye computed from the wave-front sensor is in fair, though not complete, agreement with that obtained under similar conditions on the same observers by use of the double-pass and the interferometric techniques. Irregular aberrations, i.e., those beyond defocus, astigmatism, coma, and spherical aberration, do not have a large effect on retinal image quality in normal eyes when the pupil is small (3 mm). However, they play a substantial role when the pupil is large (7.3-mm), reducing visual performance and the resolution of images of the living retina. Although the pattern of aberrations varies from subject to subject, aberrations, including irregular ones, are correlated in left and right eyes of the same subject, indicating that they are not random defects.

Humans↗
PubMed1997

Supernormal vision and high-resolution retinal imaging through adaptive optics.

Even when corrected with the best spectacles or contact lenses, normal human eyes still suffer from monochromatic aberrations that blur vision when the pupil is large. We have successfully corrected these aberrations using adaptive optics, providing normal eyes with supernormal optical quality. Contrast sensitivity to fine spatial patterns was increased when observers viewed stimuli through adaptive optics. The eye's aberrations also limit the resolution of images of the retina, a limit that has existed since the invention of the ophthalmoscope. We have constructed a fundus camera equipped with adaptive optics that provides unprecedented resolution, allowing the imaging of microscopic structures the size of single cells in the living human retina.

Contrast Sensitivity↗
PubMed1997

[Changes of serum TNF-alpha level, t-PA activivty and PAI activity in patients with silent myocardial ischemia or silent cerebral ischemia].

Tumor necrosis factor-alpha (TNF-alpha) level, tissue-typed plasminogen activator(t-PA) activity and PA inhibitor (PAI) activity were determined in three groups: (1) 25 NIDDM patients with silent myocardial ischemia (SMI) or silent cerebral ischemia (SCI); (2) 18NIDDM patients without SMI or SCI; (3) 20 age-matched normal controls. Diagnosis of SMI or SCI was based on the finding of ischemic evidence by SPECT of myocardiotomograph or cerebrotomograph. All patients ECG and blood pressure were normal, and they had no history of clinical symptoms and signs of MI or CI. The result showed that the TNF-alpha level and PAI activity in the ischemia group were the highest and the t-PA activity in the ischemia group was the lowest, as compared with those in the other two groups respectively. It suggests that in NIDDM patients who have high TNF-alpha, high PAI activity, low t-PA, and even no symptoms and signs of MI or CI, anticoagulant therapy might be useful to prevent the progression of diabetic macroangiopathies.

Brain Ischemia↗
PubMed1997

[The study on insulin secretion function of beta-cell in new diagnosed type II diabetic patients].

To determine type II diabetes in association with alteration in beta-cell function, we studied 30 patients with newly diagnosed diabetes and 30 matched controls. The beta-cell 1st phase insulin response was measured by intravenous glucose tolerance test and the 2nd phase insulin response was measured by oral glucose tolerance test. The results revealed that in type II diabetes mellitus the pulse of 1st phase insulin secretion could not be found. The amount of 2nd phase insulin secretion of the patients was lower than that normal controls, and the patients' secretary pulse of insulin was not concomitant with glucose pulse. These findings again suggest it is the defect in beta-cell function, not the peripheral resistance an essential cause of overt type II diabetes.

Diabetes Mellitus, Type 2↗
PubMed1997

[Objective assessment of visual acuity with visual evoked potential].

PURPOSE: To study the technique for objectively assessment of visual acuity with Pattern Visual Evoked Potential (PVEP) and Discrete Fourier Transform (DFT). METHOD: Thirty-three normal eyes were tested in this study. Reversal square-wave gratings of eight different sizes (30, 20, 18, 12, 10, 6, 4, 2 min. of arc) were used as stimuli. The reversal rate of the stimuli was 10 times/sec. The harmonic amplitudes of VEP at 10 Hz were calculated with Discrete Fourier Transform. A relation curve between the harmonic amplitude and the size of grating was plotted from the data of each tested eye. Regression line was fitted to the data points in the approximately linear section of the curve which is near the threshold of zero amplitude. The threshold of the grating size was obtained by extrapolating of the regression line to zero amplitude, and the visual acuity was assessed with the threshold. RESULT: In seventy percent of tested eyes, the visual acuities assessed with VEPs were consistent with those measured with the International Standard Test Chart. CONCLUSION: The VEP technique for visual acuity assessment is reliable.

Adolescent↗
PubMed1997

[The objective evaluation of the interaction between color vision and motion perception].

PURPOSE: To measure equiluminance values of green/red grating luminosity ratios with different moving velocity in normal subjects and to explore the interaction between color vision and motion perception. METHODS: Optokinetic nystagmus (OKN) of eye movement elicited by moving color grating stimulus could be recorded with electrooculograph (EOG). The equiluminance points were determined when OKN changed in direction in various moving velocities. Sixteen cases (32 eyes) normal subjects were tested, 6 cases male and 10 cases female, Age ranged from 20 to 51 years old. RESULTS: The mean equiluminance points were 0.525, 0.425, 0.397, 0.391, 0.367 under 595, 400, 301, 239 and 200 mm/s groups of grating moving velocity respectively. There were statistically significant differences of mean equiluminance points among 595 mm/s group and other groups (P < 0.01), there were no statistically significant differences of mean equiluminance points among other 4 groups (P > 0.05). CONCLUSION: There are some influences to color vision under the high moving condition.

Adult↗