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Biomedical subjects

H Liu

Publications and source records attributed to H Liu.

At least 847 records · Page 47Linked to original sources
PubMed1997

Modulation of hormone-induced calcium oscillations by intracellular pH in rat hepatocytes.

Single isolated rat hepatocytes were used to investigate the influence of intracellular pH (pHi) on hormone-induced cytosolic Ca2+ oscillations, using videofluorescence microscopy. Although pHi did not vary after alpha-adrenergic stimulation, manipulations of pHi induced pronounced alterations in the frequency of oscillations. Increasing the resting pHi with ammonium chloride (5-20 mM), trimethylammonium (2-10 mM), or triethylammonium (1.2-8 mM) reduced the frequency of oscillations. A change in pHi of > 0.25 was sufficient to reversibly inhibit oscillations. This effect could be overcome by increasing the agonist concentration or by adding 8-bromoadenosine 3',5'-cyclic monophosphate, an agent known to potentiate the alpha-adrenergic response. Cellular acidification, obtained by the ammonium prepulse method as well as by application of acetate or the ionophore nigericin, in the continuous presence of agonist was accompanied by a modest frequency increase of the oscillations, leading in some cases to an overstimulated state. This study indicates that pHi, within a range of values expected to occur in vivo (0.1-0.2 pH units), exerts a chronotropic effect on phenylephrine-induced Ca2+ oscillations. In contrast, oscillations induced by ADP or vasopressin were pHi invariant.

Adrenergic alpha-Agonists↗
PubMed1997

Role of NO on vasopressin and oxytocin release and blood pressure responses during osmotic stimulation in rats.

NG-nitro-L-arginine methyl ester (L-NAME, 250 micrograms/5 microliters), an inhibitor of nitric oxide (NO) synthase, or artificial cerebrospinal fluid (5 microliters) was administered intracerebroventricularly to conscious naive rats or to rats treated subcutaneously (15 microliters/kg) with NaCl (0.15, 0.45, or 1.0 M) or given a needle prick only. Intracerebroventricular injection of L-NAME increased plasma concentration of vasopressin (VP) and oxytocin (OT) in control naive rats, indicating that NO tonically inhibits basal secretion of both hormones during isosmotic isovolemic conditions. Osmotic stimulation with hypertonic saline (0.45 and 1.0 M NaCl) elevated plasma levels of both hormones as expected. Central blockade of NO synthase further enhanced secretion of OT during mild, but not strong, osmotic stimulation, whereas the high levels of VP remained unaffected by L-NAME. In animals treated with the needle prick or 0.15 M NaCl, only OT levels were increased after L-NAME. Therefore, NO selectively inhibits OT release in response to a painful stimulus (needle prick) and moderate osmotic stimulation to promote a preferential release of VP. A transient pressor response was observed after subcutaneous injection of 0.15 and 0.45 M NaCl, but a sustained response was obtained after 1.0 M NaCl. Regardless of whether the animals received NaCl solutions, however, treatment with L-NAME elevated blood pressure in all animals. Thus NO-induced vasodilation maintains basal arterial blood pressure and limits the pressor response to osmotic stimulation.

Animals↗
PubMed1997

The three-dimensional hydrodynamics of tadpole locomotion.

Tadpoles are unusual among vertebrates in having a globose body with a laterally compressed tail abruptly appended to it. Compared with most teleost fishes, tadpoles swim awkwardly, with waves of relatively high amplitude at both the snout and tail tip. In the present study, we analyze tadpole propulsion using a three-dimensional (3D) computational fluid dynamic (CFD) model of undulatory locomotion that simulates viscous and unsteady flow around an oscillating body of arbitrary 3D geometry. We first confirm results from a previous two-dimensional (2D) study, which suggested that the characteristic shape of tadpoles was closely matched to their unusual kinematics. Specifically, our 3D results reveal that the shape and kinematics of tadpoles collectively produce a small 'dead water' zone between the head-body and tail during swimming precisely where tadpoles can and do grow hind limbs--without those limbs obstructing flow. We next use our CFD model to show that 3D hydrodynamic effects (cross flows) are largely constrained to a small region along the edge of the tail fin. Although this 3D study confirms most of the results of the 2D study, it shows that propulsive (Froude) efficiency for tadpoles is overall lower than predicted from a 2D analysis. This low efficiency is not, however, a result of the high-amplitude undulations of the tadpole. This was demonstrated by forcing our 'virtual' tadpole to swim with fish-like kinematics, i.e. with lower-amplitude propulsive waves. That particular simulation yielded a much lower Froude efficiency, confirming that the large-amplitude lateral oscillations of the tadpole do, indeed, provide positive thrust. This, we believe, is the first time that the unsteady flow generated by an undulating vertebrate has been realistically modelled in three dimensions. Our study demonstrates the feasibility of using 3D CFD methods to model the locomotion of other undulatory organisms.

Animals↗
PubMed1997

The molecular response to reductive stress in LLC-PK1 renal epithelial cells: coordinate transcriptional regulation of gadd153 and grp78 genes by thiols.

Organic thiols are toxic to eukaryotic cells. Treatment of cells with thiols activates expression of grp78, but it is not known if, like other forms of stress, there is a battery of stress response genes that are induced by thiols. In LLC-PK1 renal epithelial cells, mRNAs for both grp78 and gadd153 were induced by thiols with similar time, concentration and structure-activity dependence. Dithiothreitol (DTT) was the most potent reductant and inducer of gene expression among the thiols tested. Nuclear run-on assays demonstrated that DTT activated both grp78 and gadd153 genes transcriptionally. A hamster gadd153 promoter construct which contains enhancer elements necessary for gadd153 activation was stably integrated into the LLC-PK1 cell genome and was activated by DTT. Although auto-oxidation of thiols can generate active oxygen species, transcriptional activation of the gadd153 promoter was not due to formation of hydrogen peroxide or superoxide since neither catalase nor superoxide dismutase prevented activation of the gadd153 promoter by DTT. The concentration dependence for activation of the gadd153 promoter correlated with inhibition of dome formation and protein synthesis, two toxic effects of DTT in LLC-PK1 cells. Thus, both grp78 and gadd153 are members of a gene battery which is responsive to reductive stress. There appears to be considerable, but not complete, overlap between the upstream signaling pathways for activation of both genes.

Animals↗
PubMed1997

[Electrocardiographic signs of atrial overload in hypertension].

The aim of the study was to investigate the incidence of the ECG signs of atrial overload in hypertensive patients (HT) and its relationship to the state of the illness and cardiac function. ECG, mechanocardiogram and impedance cardiogram were performed in eighty-two HT and found P > 0.10, P/P-R > 1.6, P-S4 < 140 ms were more common (50%-73.2%) than PEP/LVET (46.3%) and DATI (29.1%). P/P-R = 1.96 +/- 0.588 in Stage 1 of HT, 2.204 +/- 0.678 in Stage 2 showed that P/P-R had a definite relationship to the stage of disease (P < 0.05). For those P-S4 were abnormal the PEP/LVET was increased and DATI decreased. All of these showed a simultaneity in ECG signs of atrial overload embodied the abnormal diastolic function of ventricle. In further analyses, P(ECG), A(ACG) and S4(PCG) may be changed but not keeping synchronous, so they can not be replaced with each other.

Adolescent↗
PubMed1997

[Experimental studies of jiantang oral solution on reducing glycemia].

Mice or rats were pretreated P. O. with 8.0 gg.kg-1, 15.0 g.kg-1 and 30.03 g.kg-1 of Jiangtang Oral Solution once daily for 10 days respectively. The results showed that Jiangtang Oral Solution did not affect the glycemia and lipid in normal mice and rats, but significantly lowered the blood sugar in hyperglycemic mice and rats induced by alloxan, adrenalin, and streptozotocin. Meanwhile, Jiangtang Oral Solution significantly lowered blood lipid in mice and rats induced by yolk and high cholesterol foods. This study provides a reliable pharmacologic base for the clincal use of Jiangtang Oral Solution.

Animals↗
PubMed1997

[Cultivation of intra-pulmonary arteriolar smooth muscle cell from rabbit].

By perfusion with trypsin at low concentration, the intra -pulmonary arterioles were separated carefully and cut into fine tissue pieces. These pieces were then washed with culture medium and used for culture of smooth muscle cells by method of adhesion to wall. Cells cultured were typical smooth muscle cells under light microscope, electron microscope and immunohistochemical test. The method is simple and convenient. It is also applicable to culture of vascular smooth muscle cells from other organs and provides ideal materials for vascular physiopathologic studies.

Animals↗
PubMed1997

[The relationship between environmental concentration and exposure concentration in the airborne dust of workplace].

The authors studied the relationship between environmental concentration and exposure concentration in the airborne dust of workplaces, using instantaneous fixed points sampling and personal wear sampling. The results showed that there was a correlation between two kinds of concentrations in the automatic and man-made packing workplaces (r = 0.9914, 0.9977). A relationship between them in the unsteady workplace was found after analysed by one-accumulated generating operation (1-AGO) (r = 0.9945). The samples of environmental and exposure concentrations could be thought from the same normal distribution, that is, the bivariable random sampling in the normal distribution population. Moreover, the exposure concentration could be estimated by environmental one after 1-AGO in the unsteady workplace of airborne dust.

Air Pollutants, Occupational↗
PubMed1997

[The repair of injured brain by implanting embryonic cortical brain tissue preserved in Iloprost solution at 4 degrees C: experimental study].

We transplanted the fresh and Iloprost or saline preserved (3 hours) embryonic rat cortical brain tissue into the rats in which the motor cortex had been injured and compared the neurobehavioral and morphological changes. The neurobehavior of the transplanted groups was more significantly improved than that in the injured, untransplanted group. The neurobehavior of the animals of the fresh tissue group and Iloprost preserved group recovered to the preinjurylevel. The survival rate of the Iloprost preserved grafts was 90%, which was higher than that of the saline preserved grafts (P < 0.05). In comparison with the fresh grafts, however, there was no significant difference (P > 0.05). In addition, the growth volume of the Iloprost preserved grafts was more markedly increased than that of the fresh grafts (P < 0.01). We conclude that injured brain may be repaired effectively by transplantation of fetal brain cortex. The Iloprost solution not only maintains of vitality the grafts, but also promotes its survival and growth in the host brain.

Animals↗
PubMed1997

[Penetrating keratoplasty combined with pupilloplasty].

OBJECTIVE: To investigate the effect of penetrating keratoplasty combined with pupilloplasty. METHOD: The penetrating keratoplasty combined with pupilloplasty was performed on 48 eyes. They had been followed-up for 6-89 months postoperatively. RESULTS: The rate of clarity was 79.2%, and the visual acuity of 0.1 or better was restored in 64.6% after an average follow-up of 19.4 months. The pupil was repaired to approximately normal in 89.6%, and the incidence of postoperative complications, anterior synechia and glaucoma, was lowered. CONCLUSION: The results show that the combined operation can reduce the postoperative complications, improve the prognosis of grafts and vision, and is valuable for the patients with corneal opacity and gappy iris.

Adolescent↗
PubMed1997

[Assessment of nutrition in dialysis patients and chronic uremic patients].

Multiple methods were used to assess the nutritional status of 40 uremic non-dialysis or dialysis patients in order to improve their living quality as well as to provide scientific basis for nutritional treatment. The investigation of diet diaries revealed that the ratio of animal protein over total protein in food was greater in uremic dialysis patients treated with either hemodialysis or peritoneal dialysis than in the uremic non-dialysis patients (P < 0.01, P < 0.05); the daily intake of total protein in each of three groups was lower than the recommended amount. The anthropometric measurement showed: decreased muscle protein store occurred in 35% of the dialysis patients and 80% of the uremic non-dialysis patients. Serum albumin measurement revealed that hemodialysis patients had much higher level than that of peritoneal dialysis patients (P < 0.01). 50% of the hemodialysis patients, 80% of the peritoneal dialysis patients and 60% of the uremic non-dialysis patients had lower level of serum albumin than normal. Evaluation of nutritional status of hemodialysis patients and peritoneal dialysis patients by means of urea production found that 65% of the hemodialysis patients and 37.5% of the peritoneal dialysis patients were in a status of negative nitrogen balance. According to the results of all the measurements, 58% of the dialysis patients had malnutrition of various degrees.

Adult↗
PubMed1997

[Separation and purefied of calf osteocalcin, set up radioimmunoassay for osteocalcin].

OBJECTIVE AND METHODS: We extracted and purified osteocalcin (BGP) from calf femur by gel filtration, FPLC and HPLC subsequently. The rabbits were immunized by this antigen and produced antibody. With this antibody (final 1: 35,000 dilution) we established RIA for BGP. This assay is stable and sensitive, the kd was 2.29 x 10(11). The intra assay variation was 2.1% and the inter assay variaton was 5.6%. It has no crossreaction with insulin, parathyroid hormone or calcitonin. RESULTS: The serum BGP values were detected in normal subjects and six kinds of bone metabolic diseases. In 81 normal subjects, the average serum BGP level was (5.3 +/- 1.5) ng/ml and in postmenopausal osteoporosis the serum BGP level [(6.2 +/- 1.9) ng/ml, n = 42] was higher than the normal (P < 0.05). The serum BGP levels were increased much in primary hyperparathyroidism [(12.8 +/- 7.0) ng/ml, n = 21, P < 0.001]. Increased values of BGP were also found in patients with chronic renal failure [(8.5 +/- 2.4) ng/ml, n = 18, P < 0.01] and Paget's disease [(6.7 +/- 2.2) ng/ml, n = 12, P < 0.05]. Decreased serum BGP values were found in Cushing syndrome [(2.9 +/- 0.9) ng/ml, n = 16, P < 0.001] and hypoparathyroidism [(3.4 +/- 1.1) ng/ml, n = 42, P < 0.001]. This result showed that in diseases with high bone turnover, the serum BGP levels were increased and in diseases with low bone turnover, the serum BGP levels were decreased. CONCLUSION: The data suggest that serum BGP is a sensitive marker for bone turnover. It is very improtant in studying bone metabolic diseases.

Adult↗
PubMed1997

[Observation on the content of plasma lipoperoxide and serum superoxide dismutase in NIDDM nephrosis patients].

OBJECTIVE: In order to explore the changes of MDA, SOD in each period of diabetic nephrosis patients, the contents of MDA and SOD from 40 cases of NIDDM nephrosis patients in various stages and 15 cases of normal persons (control group) were measured. METHODS: By using method of sulpho-barbiamino acid to determine the concentration of serum MDA (the reagents are provided by Juli Biomedical Engineering Institute of Nanjing). By using method of radioimmunization to determine the concentration of SOD (The reagents are provided by Huaqing Biological Technic Institute of Beijing), blood sugar, T-cho, TG, Bun, Ccr, UAE, etc. in serum were simutaneouslly determined. By adopting statistical method to analyse the mean difference in each groups and the interrelation of each data. RESULTS: The results show that the content of MDA in each groups exceeds normal control group and the content of MDA of the group of diabetic kidney failure (DKF) exceeds group of diabetic kidney early stage (DKE) obviously (P < 0.01). Only trace of MDA and SOD can be detected in the liquid of peritoneal dialysis in group of DKF. The content of SOD in each groups exceeds normal control group without exception and the content of SOD in group of DKF exceeds that of the group of diabetic kidney function injury stage obviously (P < 0.01). CONCLUSION: Our results suggest that content of SOD might have some clinical value for the diagnosis and prognosis in NIDDM nephrosis and situation of kidney function injury.

Aged↗
PubMed1997

[Construction of genomic library of L. interrogans serovar lai using lambda gt11 as the vector and a study of recombiant plasmid pDL121].

A genomic library of L. interrogans serovar lai strain 017 has been constructed using lambda gt11 as the vector. DNA was partially digested by two blunt-end restriction enzymes, then methylated with EcoR I methylase; after EcoR I linker was added to the DNA, the linker-ended DNA was ligated to the dephosphorylated EcoR I digested lambda gt11 arms. The recombined DNA was packaged in vitro, and used to transduct E. coli Y1090 for amplification. There were 2.1 x 10(6) recombinant bacteriophages as recognized by their ability to form white plaques plated on Lac host in the presence of both IPTG and X-Ga1. A positive clone, designated lambda DL12, was screened with a rabbit anti-serum against L. interrogans serovar lai from the genomic library. The DNA from lambda DL12 was subcloned into plasmid pUC18. A recombinant (designated as pDL121) was obtained. SDS-PAGE analysis indicated that a 23 kd was expressed in E. coli JM 103 harboring pDL121. Western blotting analysis showed that a specific protein band molecular weight of 23 kd could be recognized by the rabbit antiserum against L. interrogans serovar lai strain 017.

Cloning, Molecular↗
PubMed1997

[Comparison of two extraction methods for maxingshigan decoction].

The semi-bionic extraction and the extraction with water, two methods for the Maxingshigan Decoction, were compared. The results show that the semi-bionic extraction is superior to the extraction with water in the yield of ephedrine, hydrocyanic acid, glycyrrhetinic acid, calcium ion and extract.

Calcium↗