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Biomedical subjects

P L Liu

Publications and source records attributed to P L Liu.

At least 19 recordsLinked to original sources
PubMed2006

Cowpoxvirus infection in the Patagonian cavy (Dolichotis patagonum) emerging disease in an educational animal park the first reported case.

Generalized cowpox infection in the Patagonian cavy may represent a threat to the health of immunocompromised persons. We report the first case of cowpoxvirus infection in the Patagonian cavy in an educational animal park. The mara developed extensive pox lesions, shedding large amounts of viral particles. The ending of vaccination programmes against smallpox in the late 1970's may lead to an increase in susceptibility of humans to zoonotic poxviruses.

Animals↗
PubMed2001

Ethanol potentiation of glycine-induced responses in dissociated neurons of rat ventral tegmental area.

The potentiation of glycine-induced responses by ethanol (EtOH) was studied in neurons freshly dissociated from the ventral tegmental area (VTA) of 5- to 14-day-old postnatal rats using whole-cell and gramicidin-perforated patch-clamp techniques. Under current-clamp conditions, EtOH increased glycine-induced membrane depolarization and action potential firing. Under voltage-clamp conditions, EtOH (0. 1-40 mM) alone did not elicit a current. When coapplied with glycine, EtOH enhanced the glycine-induced current in 35% (180 of 474) of the neurons. The EtOH-induced enhancement of glycine current was independent of membrane potential (between -60 and +60 mV); the reversal potential was not changed. Concentration-response analysis showed that in the presence of EtOH (10 mM), the EC(50) for glycine decreased from 25 +/- 4 to 14 +/- 3 microM; the Hill coefficient increased from 1.5 +/- 0.2 to 1.9 +/- 0.3. Kinetic analysis of glycine currents indicated that EtOH decreased the time constant of activation and increased the time constant of deactivation of glycine-gated chloride channels. EtOH may accelerate glycine association with its receptor at the agonist binding site and increase the apparent agonist affinity. Our observations suggest that, at pharmacologically relevant concentrations, EtOH alters the function of glycine receptors and thus the excitability of neonatal VTA neurons. This action of EtOH may contribute to the neurobehavioral disturbances associated with fetal alcohol syndrome.

Algorithms↗
PubMed2000

Molecular characters and morphological genetics of CAL gene in Chinese cabbage.

BcpCAL, the homologous gene of CAL, was isolated from Chinese cabbage. Unlike BobCAL of cauliflower, BcpCAL did not hold the terminating mutation in the fifth exon. After crosses of cauliflower with Chinese cabbage, the resultant hybrids failed to form curd, which implicates the genetic complement of BcpCAL to the mutated BobCAL in the function of curd formation. One of CAL gene isolated from the hybrid apparently comes from the female parent (Chinese cabbage) even though there are a few of the bases substituted and deleted. The result offers the molecular and genetic evidences for the study of biological function of CAL in morphological genetics of curd.

Base Sequence↗
PubMed2000

Leafy head formation of the progenies of transgenic plants of Chinese cabbage with exogenous auxin genes.

The experiment was performed to evaluate the progenies of plant lines transgenic for auxin synthesis genes derived from Ri T-DNA. Four lines of the transgenic plants were self-crossed and the foreign auxin genes in plants of T5 generation were confirmed by Southern hybridization. Two lines, D1232 and D1653, showed earlier folding of expanding leaves than untransformed line and therefore had early initiation of leafy head. Leaf cuttings derived from plant of transgenic line D1653 produced more adventitious roots than the control whereas the cuttings from folding leaves had much more roots than rosette leaves at folding stage, and the cuttings from head leaves had more roots than rosette leaves at heading stage. It is demonstrated that early folding of transgenic leaf may be caused by the relatively higher concentration of auxin. These plant lines with auxin transgenes can be used for the study of hormonal regulation in differentiation and development of plant organs and for the breeding of new variety with rapid growth trait.

Brassica↗
PubMed2000

[Prokaryote expression and western analysis of BcpLH gene of Chinese cabbage].

BcpLH gene preferentially expressed in folding leaf of Chinese cabbage contains dsRNA-binding domains. The cDNA of BcpLH gene was cloned into a His-fusion expression vector pET-28a (+) and was induced to express in E. coli strain BL21 (DE3). Then, the specific protein was partially purified and the rabbit was immunized to prepare the anti-serum. Meanwhile BcpLH cDNA was cloned into the pMAL-c2 containing the solubizing partner, and then the soluble protein generated. It was demonstrated from Western dot assay that the BcpLH protein was specific. The BcpLH active protein and its anti-serum made it possible to study RNA-binding activity and regulation mechanism in plant development.

Blotting, Western↗
PubMed1999

Cocaine and lidocaine have additive inhibitory effects on the GABAA current of acutely dissociated hippocampal pyramidal neurons.

Inhibition mediated by gamma-aminobutyric acid (GABA) is a major target for the central actions of cocaine and lidocaine, which can result in seizures, especially when these drugs are abused in combination. In the present study, we investigated how cocaine and lidocaine interact to depress GABA current (IGABA), recorded by the whole-cell technique in freshly isolated rat hippocampal neurons. Cocaine depressed IGABA in a concentration dependent manner, such that cocaine was more potent against lower than higher GABA concentrations: the cocaine IC50 was 0.13, 0.62 and 1.2 mM for GABA at 2, 10 and 100 microM, respectively. Cocaine depressed IGABA to the same extent in the absence and presence of 1 microM tetrodotoxin, indicating that cocaine inhibition of IGABA is distinct from its Na+ channel blocking action. Lidocaine reversibly depressed IGABA evoked by 10 microM GABA, with an IC50 of 9.8 mM. In the presence of 3 mM lidocaine, 0.3 mM cocaine depressed IGABA (10 microM GABA) to 30+/-7%. The significantly greater depression by the combined agents (p<0.05) indicates additive effects on the GABA receptor/channel complex, which are likely to contribute to the additive convulsant effects noted when these drugs are abused in combination.

Anesthetics, Combined↗
PubMed1999

Cocaine decreases the glycine-induced Cl- current of acutely dissociated rat hippocampal neurons.

The effects of cocaine on glycine-induced Cl- current (I(GLY)) of single neurons, freshly isolated from the rat hippocampal CA1 area, were studied with conventional whole-cell recording under voltage-clamp conditions. Cocaine depressed I(GLY) in a concentration-dependent manner, with an IC50 of 0.78 mM. Preincubation with 1 mM cocaine alone had no effect on I(GLY), suggesting that resting glycine channels are insensitive to cocaine. The depression of I(GLY) by cocaine was independent of membrane voltage. Internal cell dialysis with 1 mM cocaine failed to modify I(GLY). Because the depression of I(GLY) was noncompetitive, cocaine may act on the glycine receptor-chloride ionophore complex at a site distinct from that to which glycine binds. The cocaine suppression of I(GLY) was unaffected by 1 microM tetrodotoxin and 1 microM strychnine. Blockers of protein kinase C (Chelerythrine), kinase A (N-[2-((p-bromocinnamyl)amino)ethyl]-5-isoquinolinesulfonamide HCl, (H-89)) and Ca-calmodulin-dependent kinase (1-[N,O-bis(5-isoquinoline-sulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperaz ine (KN-62)) were also ineffective, which suggests that these phosphorylating mechanisms do not modulate cocaine-induced suppressant action on I(GLY). This extracellular, strychnine-independent depression of I(GLY) may contribute to cocaine-induced seizures.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1999

Inhibitory effect of ondansetron on glycine response of dissociated rat hippocampal neurons.

We examined the effect of ondansetron, an antagonist of type 3 serotonin receptors, on the whole cell response of freshly isolated hippocampal CA1 pyramidal neurons of neonatal and "mature" rats to glycine using the gramicidin perforated patch technique. Ondansetron depressed the current induced by subsaturating concentrations of glycine (IGly) in a concentration-dependent manner. The ondansetron concentration needed to depress IGly induced by 30 microM glycine to half amplitude was 25 microM. Ondansetron (54 microM) shifted the glycine concentration-response curve to the right in a parallel manner, increasing the EC50 for glycine from 40 +/- 3 microM to 70 +/- 5 microM. Ondansetron increased the time constant of activation of IGly without affecting the time constant of deactivation. When examined under current clamp conditions, glycine induced depolarization and hyperpolarization in neonatal and mature neurons, respectively; ondansetron also suppressed these responses to glycine. The data suggest that ondansetron competitively inhibits the glycine receptor.

Animals↗
PubMed1998

Glycine-activated chloride currents of neurons freshly isolated from the ventral tegmental area of rats.

Properties of whole-cell glycine currents (IGly) of ventral tegmental area (VTA) neurons from 3- to 7-day old Sprague-Dawley rats were investigated with the patch-clamp technique. Ninety-three percent of the 126 neurons examined produced IGly in response to glycine. For 70% of these neurons, IGly did not decay in response to a threshold concentration of glycine (1-5 microM). At elevated glycine concentrations, IGly consistently decayed from a peak to a steady state (SS). IGly increased in amplitude sigmoidally as a function of the concentration of agonist with an EC50 of 32 microM. Strychnine (STR), when co-applied with glycine after a prepulse of STR, suppressed both the peak and SS IGly noncompetitively. In the absence of a prepulse, STR had a smaller effect on peak IGly while increasing its decay rate; the SS amplitude decreased. These STR effects were concentration dependent with an IC50 of 31 nM and 184 nM STR for the peak and SS IGly, with prepulse, respectively, and 732 nM and 193 nM for the peak and SS IGly, respectively, without prepulse. Picrotoxin (PTX) co-applied with glycine suppressed both the peak and the SS IGly with an IC50 of 25 microM. In contrast to STR, 1 min preincubation with PTX had no effect on IGly. Thus, PTX acts on the open channel. The inhibitory effects of both STR and PTX on IGly did not depend on the membrane potential.

Animals↗
PubMed1997

Cocaine depresses GABAA current of hippocampal neurons.

Although blockade of dopamine re-uptake and the resulting elevation of excitatory agonists is commonly thought the primary mechanism of cocaine-induced seizures, it is possible that other neurotransmitters such as gamma-aminobutyric acid (GABA) are involved. To examine this possibility, the effects of cocaine on the whole cell GABA current (IGABA) of freshly isolated rat hippocampal neurons were investigated with the patch-clamp technique. Preincubation or acute application of cocaine reversibly suppressed IGABA. The IC50 was 127 microM when cocaine was applied before the application of GABA. The concentration-response relations of cocaine in various GABA concentrations revealed that cocaine inhibited IGABA non-competitively. This effect of cocaine appeared to be independent of voltage. The present study suggests that the GABA receptor/channel complex is also a target for cocaine's action. The suppression of IGABA may contribute to cocaine-induced seizures.

Animals↗
PubMed1997

[The complementarity of pharmacologic action between Tripterygium wilfordii and prednisone].

OBJECTIVE: To investigate the effects of Tripterygium wilfordii (TW) and prednisone on hypothalamic-pituitary-adrenal (HPA) axis in adjuvant arthritis (AA). METHODS: Experimental rats were divided into five groups at random, namely the normal group, model group, TW group, prednisone group and alternative group. Rats were given and intradermal injection of complete Freun d's adjuvant in right hind paws to induce adjuvant arthritis. The levels of plasma adrenocorticotropic hormone (ACTH) and cortisol, adrenal weights and pathological changes were studied at the end of experiment. RESULTS: The levels of plasma ACTH and cortisol and adrenal weights in TW group were significantly higher than those in normal group. On the contrary, decreased plasma ACTH and cortisol levels and atrophic adrenal cortex were observed in prednisone group. The levels of plasma ACTH and cortisol and adrenal weights in alternative group were not significantly different from those in normal group. CONCLUSION: TW may play anti-inflammatory role by the activation of the HPA axis, and alternative application of TW and prednisone could keep the normal function of HPA axis, they were complementary to each other.

Adrenal Glands↗
PubMed1996

Clinical experience with holmium:YAG laser lithotripsy of ureteral calculi.

BACKGROUND AND OBJECTIVE: We recently acquired a holmium:YAG laser with wavelength of 2.1 microns. We would like to report our success in using this machine for laser lithotripsy. STUDY DESIGN/PATIENTS AND METHODS: Forty-seven ureteroscopic laser lithotripsies were performed in 44 patients (three bilateral stones) over a 6 month period. Four stones were in the upper ureter, six in the middle ureter, and 37 in the lower ureter. The holmium laser beam was delivered via a 400 micron flexible quartz fiber through a 7 Fr rigid ureteroscope during the procedure. The stone size varied from 4 to 21 mm. RESULTS: The success rate was 91%. Most of the stones were fragmented to less than 2 mm in size. Larger fragments were removed with a Dormia basket (six cases) for stone clearance. Endoscopic laser ureterotomy was performed in two patients with stricture below the stone. One patient required conversion to open ureterolithotomy, and three required subsequent Extracorporeal Shock Wave Lithotripsy. A low complication rate was observed. CONCLUSION: The pulsed holmium:YAG laser is safe and effective for use in ureteroscopic laser lithotripsy.

Adult↗
PubMed1996

Mechanism of fluid secretion common to aglomerular and glomerular kidneys.

Isolated renal proximal tubules of sea water fish net secrete fluid in vitro. The principal electrolytes in secreted fluid are Na, Cl, Mg and S. Transepithelial voltages may be lumen-negative or -positive by a few millivolts, and transepithelial resistances are low partly due to high paracellular Na and Cl permeabilities. Transepithelial electrochemical potentials indicate secretion of Mg into the tubule lumen by active transport. As Mg concentration in secreted fluid rises, Na concentration falls. Surprisingly, these observations of fluid secretion are made in glomerular and aglomerular proximal tubules, suggesting a fundamental mechanism common to both. Central to this commonality appears to be their behavior as open Donnan systems. Mg actively secreted into the tubule lumen from which it cannot diffuse back into the peritubular medium causes the transepithelial secretion of diffusible Na and Cl. Water follows by osmosis. Since there is flow out of the distal end of the tubule Donnan equilibrium is not attained. Instead, a dynamic Donnan system is maintained, driven by active transport of Mg. A mathematical model of tubular electrolyte and fluid secretion confirms the operation of this open, dynamic Donnan system in aglomerular and glomerular proximal tubules.

Animals↗
PubMed1996

[Clinical and experimental study on sustained release tablet of Tripterygium wilfordii in treating rheumatoid arthritis].

Adopt to the prospective, multi-center, random, single-blind, equal rank-control methods, 226 patients of rheumatoid arthritis diagnosed according to the ARA criteria, were divided into 2 groups. One hundred and fourteen patients of test group were treated with sustained release tablets of Tripterygium wilfordii (TW-SR) orally, 2 tablets, twice a day for 4 weeks, 112 patients of control group received tablets of Tripterygium wilfordii (TW) orally, 2 tablets 3 times per day for 4 weeks. Results showed that the total effective rate of the two groups were 92.11% and 90.65%, respectively (P > 0.05). The adverse reaction rate of TW-SR group was 20.18%, which was lowered than that of TW group (70.54%, P < 0.01). Results of pre-clinical pharmacologic experimental study showed that the TW-SR has obvious anti-inflammatory, analgesia and immunosuppress'ive action as the TW has, while its toxicity was less than the latter significantly.

Adult↗
PubMed1995

[Clinical observation on treatment of myelodysplastic syndromes with yisuikang].

20 cases of myelodysplastic syndrome (MDS) patients were treated with Yisuikang (YSK) including MDS-RA 17 cases, MDS-RAEB 2 cases, MDS-RAEB-T 1 case. 14 patients were treated with YSK only, 6 cases were treated with both YSK and Western medicine. The result showed that 4 cases were remitted, 5 cases markedly improved, 6 cases improved and 5 cases ineffective, the total effective rate was 75.0%. It was found that YSK was effective in the treatment of MDS-RA or Qi-Blood Deficiency and Yu-Re Syndrome in TCM, while any other types were ineffective. They also found that types of TCM might be correlated with MDS.

Adolescent↗
PubMed1994

Effect of Tripterygium Wilfordii on adrenal cortex in rat with adjuvant arthritis.

This paper reports the effects of Tripterygium Wilfordii (TW) on adrenal cortex in rats with adjuvant arthritis. Forty rats were divided into 5 groups. Adjuvant arthritis (AA) models were made with complete freund's adjuvant (CFA) in groups I-IV. Each of which was treated with sodium carboxyl methyl cellulose, TW, prednisone and cyclophosphamide respectively. The untreated rats allocated to group V served as normal controls. The swelling of AA markedly subsided in group II, III and IV as compared with group I (P < 0.01), whereas no significant differences were noted among groups II, III and IV (P > 0.05). The obviously increased plasma corticosterone levels and decreased adrenal ascorbic acid levels were observed in group II, whereas decreased plasma corticosterone levels and increased adrenal ascorbic acid levels were noted in group III. There was a striking contrast between groups II and III. The morphological changes of adrenal glands under light microscope revealed hypertrophic adrenal cortices in group II, and atrophic adrenal cortices in group III. The above findings suggest that the effect of promoting production of corticosteroids may be one of the mechanism by which TW can effectively treating autoimmune diseases.

Adrenal Cortex↗
PubMed1992

Renal function in unilateral nephrectomy subjects.

Renal function in 32 subjects who had undergone unilateral nephrectomy (17 transplant donors and 15 subjects with unilateral renal disease) was compared with that of 22 normal subjects. The age-adjusted glomerular filtration rate was lower in transplant donors (79 +/- 15% of normal) than in those whose nephrectomy was performed for unilateral renal disease (90 +/- 12% of normal). The donors were also significantly older at nephrectomy (48 +/- 10 years versus 24 +/- 13 years, p less than 0.001). This finding may represent less capacity for compensatory hypertrophy. Proximal tubular and medullary function as assessed by 15-minute phenolsulfonphthalein excretion, maximum urinary concentration in response to water deprivation plus exogenous vasopressin, and urinary acidification in response to an oral acid load were all within normal limits for glomerular filtration rate. Overall renal function was well preserved after nephrectomy. A small number of patients did have increased cast excretion, which may signify the presence of mild renal disease in these subjects.

Adult↗