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Biomedical subjects

X H Li

Publications and source records attributed to X H Li.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Experimental study on functional rehabilitation of peripheral nerve with electric acupuncture].

OBJECTIVE: To observe the functional rehabilitation of injured peripheral nerve with electric acupuncture. METHODS: Sciatic nerve injury model was established by transection of left sciatic nerve in 60 Wistar rats, which were randomly divided into two groups. The experimental group was treated with electroacupuncture, no treatment in the control group. Change of nerve electrophysiological, power of muscle and sciatic functional index (SFI) were observed. RESULTS: Nerve muscle-action potential (MAP) and motor nerve conduction velocity (MNCV) in the experimental group were better than that of the control group (P < 0.01). The single muscle twitch and tetanization of gastrocnemius muscle were higher in the experimental group too (P < 0.05). SFI were significantly higher in the experimental group (P < 0.05). CONCLUSION: Electric acupuncture therapy can improve functional rehabilitation of injured peripheral nerve.

Acupuncture Therapy↗
PubMed2001

[Studies on the stability of ligustilide with solvent effect].

AIM: To study the stability of ligustilide with solvent effect and try to disclose the relationship between its stability and solvent effect, so as to develop a useful method for its preservation. METHODS: The model of PCM solvent effect was used to carry out quantum chemistry calculation. The GC/MS spectrum was used to study the stability of ligustilide in solvent at room temperature. RESULTS: Ligustilide is more stable in cyclohexane and chloroform than in air. The isomerization rate of ligustilide decreased remarkably to 1.6% and 6.7% in cyclohexane and chloroform compared to 58% in air. CONCLUSION: The stability of ligustilide is greatly improved with the solvent effect. Keeping ligustilide in proper organic solvent is helpful to prevent its isomerization.

4-Butyrolactone↗
PubMed2000

Role of IKKgamma/nemo in assembly of the Ikappa B kinase complex.

IKKgamma/NEMO is a protein that is critical for the assembly of the high molecular weight IkappaB kinase (IKK) complex. To investigate the role of IKKgamma/NEMO in the assembly of the IKK complex, we conducted a series of experiments in which the chromatographic distribution of extracts prepared from cells transiently expressing epitope-tagged IKKgamma/NEMO and the IKKs were examined. When expressed alone following transfection, IKKalpha and IKKbeta were present in low molecular weight complexes migrating between 200 and 400 kDa. However, when coexpressed with IKKgamma/NEMO, both IKKalpha and IKKbeta migrated at approximately 600 kDa which was similar to the previously described IKK complex that is activated by cytokines such as tumor necrosis factor-alpha. When either IKKalpha or IKKbeta was expressed alone with IKKgamma/NEMO, IKKbeta but not IKKalpha migrated in the higher molecular weight IKK complex. Constitutively active or inactive forms of IKKbeta were both incorporated into the high molecular weight IKK complex in the presence of IKKgamma/NEMO. The amino-terminal region of IKKgamma/NEMO, which interacts directly with IKKbeta, was required for formation of the high molecular weight IKK complex and for stimulation of IKKbeta kinase activity. These results suggest that recruitment of the IKKs into a high molecular complex by IKKgamma/NEMO is a crucial step involved in IKK function.

Animals↗
PubMed2000

Mechanisms of NF-kappaB activation by the HTLV type 1 tax protein.

The Tax protein encoded by the human T cell leukemia virus type I virus (HTLV-1) activates the expression of both viral genes and cellular genes involved in T lymphocyte growth and proliferation. One of the critical cellular pathways activated by Tax is NF-kappaB. NF-kappaB is normally sequestered in the cytoplasm, bound to a family of inhibitory proteins known as I-kappaB. In contrast to the transient activation of the NF-kappaB pathway seen in response to cytokines, Tax results in constitutive nuclear levels of NF-kappaB. Tax activation of the NF-kappaB pathway is mediated by its ability to enhance the phosphorylation and subsequent degradation of I-kappaB. The persistent activation of the NF-kappaB pathway by Tax is believed to be one of the major events involved in HTLV-1-mediated cellular transformation of T lymphocytes. This review summarizes data exploring the role of Tax in activating the NF-kappaB pathway and discusses our studies to determine the mechanism by which Tax activates the NF-kappaB pathway.

Cell Nucleus↗
PubMed2000

Stimulatory effect of oral administration of green tea or caffeine on ultraviolet light-induced increases in epidermal wild-type p53, p21(WAF1/CIP1), and apoptotic sunburn cells in SKH-1 mice.

Pretreatment of SKH-1 mice with p.o.-administered 0.6% green tea (6 mg of lyophilized tea solids/ml) or 0.044% caffeine (0.44 mg/ml; concentration present in 0.6% green tea) for 2 weeks enhanced UV-induced increases in the number of p53-positive cells, p21(WAF1/CIP1)-positive cells, and apoptotic sunburn cells in the epidermis. These effects of p.o.-administered green tea or caffeine on early adaptive responses to UV provide the first demonstration of in vivo up-regulation of a tumor suppressor gene by a chemopreventive agent. The stimulatory effect of green tea and caffeine on UV-induced increases in the number of p53-positive cells, p21(WAF1/CIP1)-positive cells, and apoptotic sunburn cells may play a role in the inhibitory effects of tea and caffeine on UV-induced carcinogenesis.

Adaptation, Biological↗
PubMed2000

Formation of 6-nitro-norepinephrine from nitric oxide and norepinephrine in the spinal cord and its role in spinal analgesia.

Spinally released norepinephrine is thought to produce analgesia in part by stimulating alpha(2)-adrenergic receptors, which in turn leads to nitric oxide synthesis. Also, nitric oxide is known to react with norepinephrine in vivo in the brain to form 6-nitro-norepinephrine, which inhibits neuronal norepinephrine reuptake. In the present study, we tested the hypothesis that formation of 6-nitro-norepinephrine occurs in the spinal cord and that intrathecal administration of 6-nitro-norepinephrine produces analgesia by stimulating norepinephrine release. 6-Nitro-norepinephrine was present in rat spinal cord tissue and microdialysates of the dorsal horn and intrathecal space. Intrathecal norepinephrine injection increased 6-nitro-norepinephrine. 6-Nitro-norepinephrine also stimulated norepinephrine release in dorsal spinal cord in vitro. Intrathecal injection of 6-nitro-norepinephrine produced antinociception and interacted additively with norepinephrine for antinociception. Spinal noradrenergic nerve destruction increased antinociception from intrathecally injected norepinephrine, but decreased antinociception from 6-nitro-norepinephrine. These results suggest a functional interaction between spinal nitric oxide and norepinephrine in analgesia, mediated in part by formation of 6-nitro-norepinephrine. Stimulation of auto-inhibitory alpha(2)-adrenergic receptors at noradrenergic synapses decreases norepinephrine release. Paradoxically, alpha(2)-adrenergic agonist injection increases and alpha(2)-adrenergic antagonist injection decreases norepinephrine release in the spinal cord. 6-Nitro-norepinephrine may be an important regulator of spinal norepinephrine release and could explain the positive feedback on norepinephrine release after activation of spinal alpha(2)-adrenergic receptors.

Analgesia↗
PubMed2000

Autonomic dysfunction secondary to intracerebral hemorrhage.

IMPLICATIONS: We report a case of autonomic dysfunction secondary to intracranial hemorrhage. The patient had periodical episodes of hypertension, tachycardia, tachypnea, and diaphoresis that responded dramatically to Thorazine, but not to conventional measures.

Adult↗
PubMed2000

[Comparison of genetic diversity among maize inbred lines based on RFLPs, SSRs, AFLPs and RAPDs].

RFLPs, SSRs, AFLPs and RAPDs were used to detect the genetic diversity among 15 maize inbred lines. A total of 56 probe enzyme combinations, 66 SSR primers, 20 RAPD primers and 9 AFLP primer combinations were identified with polymorphism among the entries, which produced 167, 201, 180 and 87 alleles respectively. SSR markers have the highest polymorphism information content (PIC, 0.47) and AFLP markers have the lowest value (0.36), while AFLP markers possess the highest assay efficiency index (Ai, 32.4). A comparison of genetic similarity matrices revealed that the estimates of correlation coefficients based on RFLPs, SSRs, AFLPs and RAPDs were significantly correlated, but the correlation of RAPD maker data with other markers was lower. These inbred lines were classified into five groups based on four molecular markers data, which are Tangsipingtou, Luda Red Cob, Lancaster, Reid, and PN group. They are consistent with the grouping based on the available pedigree data. Based on the results, we recommend RFLPs and SSRs for genetic diversity analysis among maize germplasm.

Genetic Variation↗
PubMed2000

A nine-year prospective study on the incidence of childhood type 1 diabetes mellitus in China.

To investigate the epidemiological characteristics of childhood type 1 diabetes mellitus in China, newly diagnosed cases of type 1 diabetes with an onset age under 15 years were retrospectively registered by 23 local centers in China following a standardized protocol on the basis of the nationwide registry established by the WHO DiaMond Project China Participating Center, Chinese Academy of Preventive Medicine (CAPM). A population of about 24 million children were covered in the defined areas. A two-sample capture-recapture method was used to estimate case ascertainment. Between 1988 and 1996, 903 diabetic cases were registered in 9 ethnic groups. The overall ascertainment corrected incidence rate (IR) was 0.59 per 100,000 person-year. The IR was 0.52/100,000 (95% CI: 0.50-0.54) for males and 0.66/100,000 (95% CI: 0.64-0.68) for females. The standardized ascertainment corrected IR by the national age-specific population in 1990 was 0.57 per 100,000 person-year. The incidence among various ethnic groups ranged from 0.25/100,000 to 3. 06/100,000. The IRs increased with northern latitude, and the IR of Han population was significantly higher in North China compared with South China (0.67 versus 0.53 per 100,000 respectively, P < 0.01). A correlation model of incidence and calendar time showed that the IR increased significantly between 1988 and 1996 (r = 0.86, P = 0.0027). The relative risk (RR) of type 1 diabetes mellitus for different age-groups estimated by a Poisson regression model showed that taking RR as 1.00 for age-group from 0 to 4 years, the RR for age-group from 5 to 9 year and from 10 to 14 year was 2.30 and 3.60 respectively. The standardized ascertainment corrected IR of childhood type 1 diabetes mellitus in China in much lower than in other countries. The geographic and ethnic variability of the incidence suggests that both genetic and environmental factors play a role in the development of childhood diabetes in China.

Adolescent↗
PubMed2000

[Effects of amiloride on calcium current in thyroxine-induced hypertrophied rat heart].

AIM: The L-Type calcium currents were investigated in normal, hypertrophied and amiloride-treated rat ventricular myocytes so as to clarify the possible cause of the action potential lengthening that has been reported in thyroxine-induced hypertrophy. The interactions between agents such as thyroxine, Ang II and phenylephrine which induced hypertrophy with amiloride on the calcium current were analyzed. METHODS: Myocardial hypertrophy was induced by i.p. L-thyroxine in rats. The cell length, cell width and cell area were measured by image analysis technique. For recording ICaL, the whole cell patch clamp technique was used. Potassium currents were suppressed by replacing K+ ions with Cs+ ions in intracellular media, and sodium current was blocked by 50 mumol.L-1 tetrodotoxin. RESULTS: The Ca2+ current was found to be larger in hypertrophied cells (783pA) than in normal cells (433pA) and in amiloride-treated cells (429pA). However, no significant difference was observed in current density (6.54, 8.33, 5.74 pA/pF) in normal, hypertrophied and amiloride-treated cells. ICa displayed the same voltage dependence in three cell types. The potential giving 50% of activation (V1/2) moved towards more negative and the slope of activation curve was smaller in hypertrophied cells than in normal cells and amiloride cells. When expressed as percentages, the maximal increases in ICa were obtained with 1 mumol.L-1 Ang II and 100 mumol.L-1 phenylephrine in normal cells (+45.5% and +81.8%). Thyroxine 100 mumol.L-1 showed no effect on ICa. After giving amiloride, Ang II and phenylephrine did not increase the amplitude of ICa. CONCLUSION: At the dose of 0.5 mg.kg-1.d-1, amiloride (p.o.) was shown to prevent the amplitude of ICa from increasing and to be effective against increases of amplitude of ICa by Ang II and phenylephrine.

Amiloride↗
PubMed1999

The human T-cell leukemia virus type-1 Tax protein regulates the activity of the IkappaB kinase complex.

Two cytokine-inducible kinases, IKKalpha and IKKbeta, are components of a 700-kDa kinase complex that specifically phosphorylates IkappaB. Phosphorylation of IkappaB by IKK leads to its ubiquitination and subsequent degradation, resulting in the nuclear translocation of NF-kappaB. The oncogenic protein Tax, encoded by human T-cell leukemia virus type-1 (HTLV-1), stimulates IKK activity to result in constitutive nuclear levels of NF-kappaB. In an attempt to gain insights into the mechanism by which Tax mediates constitutive activation of the NF-kappaB pathway, we analyzed the chromatographic distribution of IKK proteins using cellular extracts prepared from three T lymphocytes either lacking or containing Tax. IKK kinase activity and the distribution of proteins in the IKK complex were characterized. In extracts prepared from cells containing Tax, the activity of both IKKalpha and IKKbeta present in the 700-kDa IKK complex were increased. Surprisingly, cell lines expressing Tax also contained an additional peak of IKKbeta, but not IKKalpha activity, that migrated at 300 kDa rather than at 700 kDa. We noted that extracts containing Tax had extremely low levels of IkappaBbeta, but not IkappaBalpha, and contained predominantly a truncated form of the MAP3K MEKK1. These results suggest that Tax may target several components of the NF-kappaB pathway leading to constitutive activation of this important regulator of cellular gene expression.

Animals↗
PubMed1999

Optimization of preparative conditions for poly-DL-lactide- polyethylene glycol microspheres with entrapped Vibrio cholera antigens.

Poly-dl-lactide-polyethylene glycol (PELA) with different contents of polyethylene glycol(PEG) were synthesized and the PEG content was estimated according to the integral height of hydrogen shown in 1H-NMR. PELA microspheres containing V. cholera antigen, outer membrane protein (OMP) were prepared by a water-in-oil-in-water (W/O/W) based on solvent evaporation procedure. Antigen microspheres with smooth surface, suitable size for oral administration (0.5-5 microm), high loading efficiency (about 60%) and low level of residual solvent (lower than 20ppm) were obtained. Microspheres prepared from PELA with PEG content of about 10% achieved the highest loading efficiency among PELA copolymers and poly-dl-lactide (PLA) homopolymer, which suggested that microspheres size, morphology and the precipitation rate of polymer showed considerable relations with OMP loading efficiency. The regulation of the solvent components of the oil phase contributes to a stable emulsion W/O, and it is concluded that the stable emulsion W/O plays a significant role in improving the protein loading efficiency of obtained microspheres. The addition of stabilizer, such as gelatin and polyvinyl alcohol, into the internal water phase before emulsification produced no significant difference in OMP entrapment and microspheres size. A higher OMP loading efficiency was achieved by adding NaCl or adjusting the pH at the iso-electric point of OMP in the external water phase. It was indicated in vitro that PELA microspheres with smaller size showed larger extent of initial release and higher release rate, whereas microspheres with the diameter of 2.17 microm showed no apparent burst effect.

Antigens, Bacterial↗
PubMed1999

Regulation of NF-kappaB by the HTLV-1 Tax protein.

The Tax protein encoded by the human T-cell leukemia virus type 1 (HTLV-1) activates viral gene expression via the ATF/CREB pathway. Tax also induces a variety of cellular genes through activation of the transcription factor NF-kappaB. The ability of Tax to activate the NF-kappaB pathway plays an essential role in HTLV-1-induced cellular transformation. This review briefly summarizes the remarkable discoveries of the past several years that have greatly advanced our knowledge on signal-mediated activation of the NF-kappaB pathway. It highlights our current understanding of how viral agents like Tax modulate cellular signaling machinery to activate the NF-kappaB pathway.

Animals↗
PubMed1999

[Favorable genes and favorable genic interactions enhancing F1 fertility in indica/japonica hybrids].

Two test cross populations were developed by crossing a set of DH lines as male parents to two wide compatibility rice lines, photoperiod-sensitive genic male sterile (PGMS) line-N422S and thermosensitive-genic male sterile (TGMS) line-Peiai64S. Polymorphism of the cross parents and another set of diverse indica or japonica lines (as a control) was assayed by using 92 RFLP markers. 41 RFLP markers were detected highly associated with indica and japonica phenotypes, which can be used as diagnostic markers to differentiate indica and japonica. Our results indicated that 87.8% of the diagnostic markers were also highly associated with grain yield and its components in at least one of the test cross populations, suggesting parallel relationships between the genes involving in evolution and QTLs controlling grain yield and yield components in the process of differentiation of rice (O. sativa L.). Further analysis indicated that fertility was a main factor affecting the heterosis for grain yield in inter-subspecific rice hybrids. The fertility was conditioned by both intra-locus and inter-locus gene interactions and favorable genic interactions could raise it accordingly.

Fertility↗
PubMed1999

Blocking L-calcium current by l-tetrahydropalmatine in single ventricular myocyte of guinea pigs.

AIM: To study the effect of l-tetrahydropalmatine (l-THP) on L-type calcium channel. METHODS: Patch clamp technique (whole cell recording) was used to record L-Ca2+ current in single cardiac myocyte. RESULTS: 1) l-THP 1, 10, and 100 micromol.L-1 reduced ICa-max from (999 +/- 93) pA to (700 +/- 111) pA, (582 +/- 66) pA, and (420 +/- 112) pA (n = 6, P < 0.01), respectively. 2) l-THP reduced the voltage at half-maximal inactivation (V1/2) of L-Ca2+ channel to more negative potentials by 9 mV (n = 5, P < 0.05). 3) l-THP caused both tonic and use-dependent reduction of Ca2+ current. Tonic block of l-THP on Ca2+ current was 46% +/- 8% (n = 6, P < 0.01). The degree of use dependent blocking was 13.5% +/- 2.4% (n = 6, P < 0.05) at 1 Hz, the degree increased to 44% +/- 5% (n = 6, P < 0.01) at 3 Hz. 4) l-THP delayed half-recovery time of Ca2+ channel recovery from inactivity from (94 +/- 39) ms to (170 +/- 42) ms(n = 6, P < 0.01). CONCLUSION: l-THP has a moderate inhibitory effect on L-Ca2+ current.

Animals↗