Metal-organic framework MIL-101 for adsorption and effect of terminal water molecules: from quantum mechanics to molecular simulation

MIL-101 is a chromium terephthalate-based mesoscopic metal-organic framework and one of the most porous materials reported to date. In this study, we investigate the adsorption of CO(2) and CH(4) in dehydrated and hydrated MIL-101 and the effect of terminal water molecules on adsorption. The atomistic structures of MIL-101 are constructed from experimental crystallographic data, energy minimization, and quantum mechanical optimization. The adsorption isotherm of CO(2) predicted from molecular simulation agrees well with experiment and is relatively insensitive to the method (Merz-Kollman or Mulliken) used to estimate the framework charges. Both the united-atom and five-site models of CH(4) predict the isotherm fairly well, though the former overestimates and the latter underestimates. Adsorption first occurs in the microporous supertetrahedra at low pressures and then in the mesoscopic cages with increasing pressure. In the dehydrated MIL-101, more adsorbate molecules are located near the exposed Cr(2) sites than the fluorine saturated Cr(1) sites. The terminal water molecules in the hydrated MIL-101 act as additional interaction sites and enhance adsorption at low pressures. This enhancement is more pronounced for CO(2) than for CH(4), because CO(2) is quadrapolar and interacts more strongly with the terminal water molecules. At high pressures, however, the reverse is observed, as the presence of terminal water molecules reduces free volume and adsorption. For the adsorption of CO(2)/CH(4) mixture, a higher selectivity is found in the hydrated MIL-101.

Proteomic analysis of differentially expressed proteins in rat liver allografts developed acute rejection

BACKGROUND

Acute rejection (AR) after liver transplantation is a cell-mediated immune response that takes place within the allograft and results in graft dysfunction and failure, but the molecular mechanisms about hepatocyte dysfunction remain poorly understood. Here we characterized global protein expression changes in liver allograft during AR.

METHODS

The effect of an alloantigen-dependent immunological response was evaluated by syngeneic and allogeneic rat orthotopic liver transplantation (OLT). Using a combination of two-dimensional gel electrophoresis and mass spectrometry, we identified 18 differentially expressed proteins in AR allograft compared with matched tolerance allograft. Serum chemistry and allograft histology were determined.

RESULTS

Allogeneic OLT recipients exhibited elevated plasma levels of liver injury markers, progressive portal and venous inflammation and cellular infiltration in liver allograft compared with syngeneic OLT. 18 protein expressions altered by AR play important roles in metabolism, oxidative stress defense, signal transduction, biotransformation and transport. Decreased expression of protein disulfide isomerase in AR allograft was confirmed by Western blotting and immunohistochemistry.

CONCLUSIONS

This study uncovered new mechanistic insights into graft dysfunction in AR of liver allograft. Several significantly altered protein expressions act coordinately in hepatocyte dysfunction by depressed energy, enhanced oxidative stress-induced molecular damage and restrained biotransformation. The present findings may open new avenues for the understanding and prevention of graft dysfunction and failure during AR.

[Survivin antisense oligodeoxynucleotides inhibits the proliferation of hepatocellular carcinoma cells and enhances the cell chemosensitivity to 5-Fu]

OBJECTIVE

To investigate the inhibitory effect of survivin antisense oligodeoxynucleotides (ASODN) mediated by polyethylenimine(PEI) on the proliferation of hepatocellular carcinoma SMMC-7721 cells, and assess its detect on the chemosensitivity of the cells to 5-FU.

METHODS

The inhibitory effect of PEI-ASODN on SMMC-7721 cell proliferation was assessed using WST-8 test, trypan blue staining, and cell clone formation test. In mice bearing transplanted hepatocarcinoma and ascites tumor derived from H22 cells, 5-FU combined with PEI-ASODN was administered, and the weight and volume of the subcutaneous tumors were measured to calculate the tumor inhibition rate, and the average survival time of the mice was calculated.

RESULTS

Incubation of the cells with different concentrations of PEI-ASODN for 48 h significantly inhibited the cell proliferation as compared with the control group, but PEI or ASODN alone produced no significant inhibitory effects. At 24, 48, 72, 96 h of incubation of the SMMC-7721 cells with 0.75 micromol/L PEI-ASODN, the cell proliferation was suppressed significantly, and incubation with PEI-ASODN at 0.25-0.75 micromol/L for 7 days resulted in significantly inhibited cell clone formation. No significant inhibition was detected in ASODN and PEI group. The tumor weight and volume were reduced in all the treated groups. The tumor inhibition rate was 56.91% and volume inhibition rate was 57.83% in 5-FU+PEI-ASODN group, significantly different from those in the normal saline group (P<0.01). In mice bearing ascites tumor, the average survival time was 22.0 days in saline group, and 42.7 days 5-FU+PEI-ASODN group. The life-prolongation rate of 5-FU+PEI-ASODN was 94.09% when compared with the survival time in saline group. A cooperative effect was detected between 5-FU and PEI-ASODN.

CONCLUSION

PEI-ASODN complex can significantly inhibit the proliferation of hepatocarcinoma SMMC-7721 cells and enhance the chemosensitivity of the tumor cells to 5-FU.

Atomistic insight into adsorption, mobility, and vibration of water in ion-exchanged zeolite-like metal-organic frameworks

The adsorption, mobility, and vibration of water in ion-exchanged rho-zeolite-like metal-organic frameworks (ZMOFs) are investigated using atomistic simulations. Because of the high affinity for the ionic framework and nonframework ions, water is strongly adsorbed in rho-ZMOFs with a three-step adsorption mechanism. At low pressures, water is preferentially adsorbed onto Na(+) ions, particularly at site II; with increasing pressure, adsorption occurs near the framework and finally in the large cage. Upon water adsorption, Na(+) ions are observed to redistribute from site I to site II and gradually hydrated with increasing pressure. In Li-, Na-, and Cs-exchanged rho-ZMOFs, the adsorption capacity and isosteric heat decrease with increasing ionic radius attributed to the reduced electrostatic interaction and free volume. The mobility of water in Na-rho-ZMOF increases at low pressures but decreases upon approaching saturation. With sufficient amount of water present, the mobility of Na(+) ions is promoted. The vibrational spectra of water in Na-rho-ZMOF exhibit distinct bands for librational motion, bending, and stretching. The librational motion has a frequency higher than bulk water due to confinement. With increasing loading and hence stronger coordinative attraction, the bending frequency shows a blue shift. Symmetric and asymmetric modes are observed in the stretching as a consequence of the strong water-ion interaction. This study provides a fundamental microscopic insight into the static and dynamic properties of water in charged ZMOFs and reveals the subtle interplay between water and nonframework ions.

[Antisense oligonucleotides targeting protein kinase C alpha inhibits the proliferation of A549 cells]

OBJECTIVE

To investigate the effects of antisense oligonucleotides (ASODN) targeting protein kinase C alpha (PKCalpha) on the proliferation of A549 cells.

METHODS

PKCalpha ASODN and random oligonucleotides (RODN) were transfected into A549 cells mediated by polyethyleneimine, and the proliferation and clone formation of A549 cells were detected by CCK-8 and clone formation assay, respectively. The expression of PKCalpha in the transfected cells was analyzed by RT-PCR and Western blotting.

RESULTS

Compared with those in the control group, PEI group and PEI-RODN group, the proliferation and clone formation of A549 cells treated with ASODN targeting PKCalpha were significantly inhibited (P<0.05). The expressions of PKCalpha mRNA and protein in PKCalpha ASODN-transfected A549 cells were significantly lower than those in the other 3 groups (P<0.05).

CONCLUSION

The PKCalpha ASODN mediated by PEI down-regutates the expression of PKCalpha gene and suppress the proliferation and clone formation of A549 cells.

[Targeting delivery effect of galactose receptor-mediated c-myc antisense oligonucleotide on human hepatocellular carcinoma cell line Bel-7402]

BACKGROUND & OBJECTIVE

Deliveries of c-myc antisense oligonucleotide (ASODN) mediated by liposome or adenvirus could suppress proliferation of human hepatocellular carcinoma cells, and tumor growth of mice hepatoma model. However, these deliveries lack targeting effects. Receptor-mediated drug delivery is being used in gene and ASODN delivery due to its high targeting efficiency. This study was to evaluate targeting delivery effect of c-myc ASODN mediated by galactose-polyethyleneimine (Gal-PEI) on human hepatocellular carcinoma cell line Bel-7402.

METHODS

Bel-7402, and lymphoma cell lines, U937 and Raji, were cultured with fluorescence-labeled Gal-PEI-c-myc ASODN, and c-myc ASODN. The uptaking rates of Gal-PEI-c-myc ASODN, and intracellular mean fluorescence intensities of Bel-7402 and U937 cells were tested by flow cytometry. Morphology of Gal-PEI-c-myc ASODN and c-myc ASODN entering Bel-7402, U937, and Raji cells was observed under phase-contrast fluorescence microscope. Effects of Gal-PEI-c-myc ASODN of various concentrations on proliferation of these cells were detected by trypan blue dye method.

RESULTS

After cultured for 10 min to 4 h, the uptaking rate, and intracellular mean fluorescence intensity of Gal-PEI-c-myc ASODN cultured Bel-7402 cells (88.25%-98.66%, and 38.61%-111.9%) were higher than those of c-myc ASODN cultured Bel-7402 cells, and Gal-PEI-c-myc ASODN cultured U937 cells, significant differences were detected by Poisson test (P < 0.01). Observed by phase-contrast fluorescence microscope, Gal-PEI-c-myc ASODN entered Bel-7402 cells effectively, but can't enter U937, and Raji cells effectively at the same concentration. C-myc ASODN can't enter Bel-7402 cells effectively at the same ASODN concentration. After incubation with Gal-PEI-c-myc ASODN (containing 0.25-1.25 micromol/L of c-myc ASODN) for 48 h, proliferation of Bel-7402 cells was significantly inhibited (P < 0.01=, but no significant differences were detected in U937, and Raji cells (P >0.05).

CONCLUSION

Gal-PEI-c-myc ASODN has high targeting delivery effect on Bel-7402 cells, which enhances the intercellular concentration of c-myc ASODN effectively, but it has no such effects on U937, and Raji cells.

Melatonin enhances lymphocyte proliferation and decreases the release of pituitary pro-opiomelanocortin-derived peptides in surgically traumatized rats

The present study was undertaken to evaluate the effects of melatonin (MT) on spleen lymphocyte proliferation and release of pituitary pro-opiomelanocortin (POMC)-derived peptides in surgically traumatized rats. MT prevented the depression of lymphocyte proliferation induced by trauma in vivo and in vitro, and prevented the decrease of beta-endorphin and adrenocorticotropin in the pituitary in vivo, but dose-dependently inhibited the release of POMC-derived peptides from the pituitary in vitro. The culture media of the pituitaries derived from the traumatized rats inhibited lymphocyte proliferation of normal rats. These results suggest that MT can improve the trauma-induced depression of lymphocyte proliferation and inhibit the release of POMC-derived peptides. The neuroimmunomodulatory role of MT and POMC-derived peptides deserves further study.

Neuroimmunal regulation of electroacupuncture (EA) on the traumatic rats

EA has a wide range of function, many of them is mediated by the release of the endogenous opioid peptides. Using surgical traumatic stress model, it was observed that EA could improve the depression of cell mediated immune response. Based on the above results, we focused our work on the elucidation of the mechanism of EA in the central nervous system. The results showed that trauma amplified the activity of peritoneal macrophage, but inhibited Orphanin FQ and its receptor NP4 transcripts in the central nervous system, in the mean time, IL-1beta transcripts in the central nervous system was also augmented. EA stimulation of"Zusanli" (St. 36) and "Lanwei" (Extra. 37) points could inhibit all the above responses, but it had no influence on the normal rat. The results suggested that EA could modulate immune response via the interaction between Orphanin FQ and IL-1beta.

[Modulatory effect of orphanin FQ on the IL-1beta transcripts in hippocampus]

Using in situ hybridization and immuno-fluorescent double labeling method, we investigated the function of orphanin FQ on interlenkin-lbeta (IL-lbeta) transcripts in hippocampus. Intracerebroventricularly (icv) administrated IL-lbeta antibody reduced IL-l and TNF-alpha secreted from peritoneal macrophage. The high level of IL-lbeta transcript in hippocampus elicited by traumatic stress was blocked by icv injection of orphanin FQ (0.55 nmol), which was reversed by orphanin FQ receptor antagonist ([phe(1)Psi(CH(2)-NH)Gly(2)] nociceptin-(1-l3)-NH(2)). Opioid receptor-like receptor transcripts were found in neuron, astrocyte and microglia. Based on the results, we conclude that orphanin FQ functions as a neuroimmune modulator, and provokes immune response via mediation of IL-lbeta derived from neuron, astrocyte and microglia in hippocampus.

Systemic infusion of naloxone reduces degeneration of rat substantia nigral dopaminergic neurons induced by intranigral injection of lipopolysaccharide

A massive degeneration of dopamine-containing neurons in the substantia nigra (SN) in the midbrain is characteristic of Parkinson's disease. Inflammation in the brain has long been speculated to play a role in the pathogenesis of this neurological disorder. Recently, we reported that treatment of primary rat mesencephalic mixed neuron-glia cultures with lipopolysaccharide (LPS) led to the activation of microglia, resident immune cells of the brain, and subsequent death of dopaminergic neurons. The LPS-induced degeneration of dopaminergic neurons was significantly attenuated by the opiate receptor antagonist (-)-naloxone and its inactive isomer (+)-naloxone, with equal potency, through an inhibition of microglial activation and their production of neurotoxic factors. In this study, injection of LPS into the rat SN led to the activation of microglia and degeneration of dopaminergic neurons: microglial activation was observed as early as 6 h and loss of dopaminergic neurons was detected 3 days after the LPS injection. Furthermore, the LPS-induced loss of dopaminergic neurons in the SN was time- and LPS concentration-dependent. Systemic infusion of either (-)-naloxone or (+)-naloxone inhibited the LPS-induced activation of microglia and significantly reduced the LPS-induced loss of dopaminergic neurons in the SN. These in vivo results combined with our cell culture observations confirmed that naloxone protects dopaminergic neurons against inflammation-mediated degeneration through inhibition of microglial activation and suggest that naloxone would have therapeutic efficacy in the treatment of inflammation-related neurological disorders. In addition, the inflammation-mediated degeneration of dopaminergic neurons in the rat SN resulting from the targeted injection of LPS may serve as a useful model to gain further insights into the pathogenesis of Parkinson's disease.

An open-label preliminary trial of sertraline for treatment of major depression after acute myocardial infarction (the SADHAT Trial). Sertraline Anti-Depressant Heart Attack Trial

BACKGROUND

Depression occurs frequently in patients with acute myocardial infarction and is associated with increased mortality rates. It is not known whether serotonin reuptake inhibitors would be safe and effective for patients with depression after myocardial infarction and whether such treatment would reduce mortality rates.

METHODS AND RESULTS

We conducted a multicenter, open-label, pilot study of sertraline treatment in patients with major depressive disorder identified 5 to 30 days after admission for acute myocardial infarction. Outcome measures included cardiovascular and hemostatic function, adverse events, and mood ratings. Twenty-six patients were enrolled in the study. During treatment there were no significant changes in heart rate, blood pressure, cardiac conduction, or left ventricular ejection fraction, and there was a trend toward reduced ventricular ectopic activity. There were no changes in coagulation measures. Bleeding time increased in 12 patients, decreased in 4 patients, and was unchanged in 2 patients. Three (12%) patients withdrew from treatment prematurely because of adverse events. Significant improvements in mood ratings occurred over the course of treatment.

CONCLUSIONS

Sertraline treatment was associated with clinical improvement and was well tolerated in >85% of the patients in this open-label treatment trial for patients with major depression after myocardial infarction. These results encourage further controlled trials to establish the effects of treatment for this high-risk population.

Glycyl-glutamine-enriched long-term total parenteral nutrition attenuates bacterial translocation following small bowel transplantation in the pig

BACKGROUND

Improvements in immunosuppression, operative procedure, and posttransplant management have made clinical small bowel transplantation (SBT) feasible. Ischemia and reperfusion injury, total parenteral nutrition (TPN), and devoidment of enteral feeding lead to graft atrophy, gut barrier dysfunction, and bacterial translocation. Glutamine (Gln) is the principal fuel for the enterocyte. The influence of Gln dipeptide-supplemented TPN, especially long-term TPN, on intestinal graft permeability and bacterial translocation is not clear following SBT in the large animal model. Therefore, we studied the effect of glutamine dipeptide, glycyl-glutamine (Gly-Gln), on bacterial translocation following SBT in the pig, which has a physiology similar to humans.

MATERIALS AND METHODS

The outbred pigs underwent segmental small bowel autotransplantation and were divided into two groups. In the STPN group (n = 5), the animal received standard TPN devoid of Gly-Gln for 28 days. In the GTPN group (n = 5), the animal received isonitrogenous (0.3 g/kg.day) and isocaloric (33 kcal/kg.day) TPN solution with 2% Gly-Gln for 28 days.

RESULTS

At the end of the experiment, Gly-Gln-enriched TPN could maintain the plasma Gln level, graft mucosal Gln and protein concentrations, and skeletal muscle Gln and protein concentrations. Gly-Gln-enriched TPN significantly decreased the bacterial number of mesenteric lymph nodes in the liver and spleen and intestinal permeability to 99mTc-DTPA. There were no significant differences in body weight gain.

CONCLUSIONS

The Gly-Gln-enriched long-term TPN may maintain the plasma Gln level, mucosal and muscle Gln, and protein concentrations and attenuate the intestinal permeability to 99mTc-DTPA and bacterial translocation following small bowel transplantation in the pig.

Naloxone and electroacunpunture (EA) improve the immune function of traumatized rats

The present study was undertaken to examine the effects of intracerebroventricular (icv) injection of naloxone (an antagonist of opioid receptors) and electroacupuncture (EA) on the natural killer (NK) cell activity, lymphocyte proliferation and induction of interleukin-2 (IL-2) production of spleen lymphocytes of surgically traumatized rats. The NK cell activity, the spleen lymphocyte proliferation and the induction of IL-2 production were all significantly inhibited following traumatization. Compared to the traumatic group, the inhibition of the NK cell activity and the induction of IL-2 production were antagonised by icv injection of naloxone. EA stimulation of Zusanli (St 36) and Lanwei (Extra 33) points reduced the immunosuppression produced by trauma. The above results show that the central endogenous opioid peptidergic system may play an important role in immunosuppression. It is suggested that the endogenous opioid peptidergic system might act as an important modulatory system between CNS and the immune system.

Depression in patients with coronary artery disease

Depression is more prevalent in patients with coronary artery disease (CAD) than in the general elderly population. Although CAD patients with depression have higher mortality rates, depression is often not recognized and treated in these patients. We administered structured psychiatric diagnostic interviews to 99 inpatients with CAD and diagnosed 23% with a major depressive episode (MDE) by DSM-IV criteria. Severity of medical illness and family history of psychopathology were indicators for increased risk for MDE. These findings may facilitate the recognition of CAD patients at greater risk for MDE.

Nucleotide sequence and expression of the genes for the alpha and beta subunits of phycocyanin in Cyanidium caldarium

The nucleotide sequence of the plastid-encoded operon containing genes for the alpha (cpcA) and beta (cpcB) subunits of phycocyanin in the unicellular red alga Cyanidium caldarium is described. cpcB is located 5' to cpcA and the two genes are separated by a 102-bp spacer region. The transcription start site of cpcBA was mapped to 80 bp upstream of the ATG initiation codon of cpcB. Promoter-like elements similar to the -10 (TATAAT) and -35 (TTGACA) consensus promoters in bacteria were found 6 and 31 bp upstream of the transcription initiation site. Northern blotting revealed an abundant 1.3-kb cpcBA transcript in illuminated cells, but this transcript was undetectable in dark-grown cells. Expression levels of cpcBA in cells incubated with 10(-6) M heme in the dark were similar to those in cells illuminated for 24 h. Cells illuminated with 150 microM gabaculine (an inhibitor of delta-aminolevulinate synthesis) or 10 mM levulinic acid (an inhibitor of delta-aminolevulinate dehydrase) lacked detectable cpcBA transcripts. In cells illuminated with 200 microM N-methyl-mesoporphyrin IX (an inhibitor of ferrocheletase), inhibition of cpcBA expression and phycocyanin synthesis was similar. These results provide strong evidence that light induction of the cpcBA operon is dependent on synthesis of heme.

Localization of the gene for human heart fatty acid binding protein to chromosome 1p32-1p33

Heart fatty acid binding protein (hFABP) is an abundant 14-kDa cytosolic protein thought to be involved in trafficking of fatty acids from the plasma membrane to sites of beta-oxidation in mitochondria and peroxisomes and to the endoplasmic reticulum for lipid synthesis. A human hFABP cDNA isolated by polymerase chain reaction was used as a probe for in situ hybridization to metaphase chromosomes. A fragment of the gene for human hFABP was used as a probe for fluorescence in situ hybridization to metaphase chromosomes. The cDNA and genomic probes both localized the gene for human hFABP to chromosome 1p32-1p33.

[Changes of endogenous opioid peptides content in RPGL during acupuncture analgesia]

By push-pull perfusion technique and RIA of neuro-peptides, it was found that after 20 minutes' electroacupunture (EA), the release of LEK from the RPGL in the EA group was significantly higher than that in the control group (P < 0.05). The release of beta-EP from the RPGL in the EA group with higher efficacy was significantly higher than that in the control group (P < 0.05), but no significant changes were found in the EA group with lower efficacy. There was a positive correlation between the changes of release of LEK or beta-EP and the increase of pain threshold. The release of DynA1-13 tends to show a barely significant extent (P > 0.05). The results indicate that acupuncture analgesia is able to increase the release of LEK and beta-EP in the RPGL.

Biological activities of melanotropic peptide fatty acid conjugates

Four fatty acids (FA, palmitic, myristic, decanoic, hexanoic) were individually conjugated to the N-terminus of the alpha-MSH fragment analog, H-Asp5-His6-D-Phe7-Arg8-Trp9-Lys10-NH2. This resulted in enhanced potency of the conjugates (compared to the unconjugated melanotropin analog) as determined in the lizard skin bioassay and in the mouse melanoma cell tyrosinase bioassay. The shorter conjugates of hexanoic and decanoic acid were at least equipotent to alpha-MSH in the lizard skin bioassay, whereas the longer myristoyl and palmitoyl analogs were 100 times less active. The myristoyl and palmitoyl conjugates exhibited a "creeping" potency in the lizard skin bioassay-that is, potency of the peptides increased with time in contact with the skins. These observations may be related to the more lipid nature of these FA-conjugates. In the tyrosinase assay, the conjugates were 10-100 times more active than alpha-MSH or the unconjugated analog. Each of the FA-melanotropic peptide conjugates exhibited prolonged (residual) melanotropic activity in both the lizard skin and melanoma cell bioassays. In other words, after removal of the melanotropin conjugates from contact with the skins or cells, responses were still manifested for hours or days thereafter. As little as 1 hr of contact with melanoma cells resulted in enhanced enzyme activity as measured 48 hr later. Since the conjugates, but not H-[Asp5, D-Phe7, Lys10]alpha-MSH5-10-NH2, exhibited prolonged activity, the conversion of reversible agonists to irreversible agonists was demonstrated.

Psoralens stimulate mouse melanocyte and melanoma tyrosinase activity in the absence of ultraviolet light

Psoralens (8-methoxypsoralen, 5-methoxypsoralen and 4,5,8-trimethylpsoralen) stimulate mouse melanoma cell (S91 and B16/F10) tyrosinase activity in vitro in a dose-related manner. Stimulation of enzyme activity by the psoralens was evoked in the presence or absence of light. In the presence of a melanotropin the actions of the psoralens were generally at least additive compared to the individual actions of the two agonists. The actions of the psoralens were acute and depended upon the constant presence of the agents to maintain enhanced melanoma tyrosinase activity. Tyrosinase activation by the psoralens, like that of alpha-melanotropin, was blocked by actinomycin-D or cycloheximide demonstrating that the actions of the drugs may have involved both transcriptional and translational events in the stimulation of melanogenesis. Psoralens also stimulated an immediate darkening of frog skins in vitro. Topically applied psoralens were transdermally delivered to the systemic circulation resulting in a conversion from pheomelanogenesis to eumelanogenesis within follicular melanocytes throughout the entire skin of mice (C57BL/6JAy maintained in the dark. Taken together, these results demonstrate that psoralens activate processes within melanocytes resulting in both an immediate translocation of melanosomes within the cell (frog) or in a slower genomic event involving tyrosinase activation (melanoma cells) and eumelanin formation (mouse follicular melanocytes).

[Potentiating effect of L-tetrahydropalmatine on the suppression of cortical tooth-pulp evoked potentials by electroacupuncture in rabbits]

Cortical potentials evoked by stimulation of the contralateral tooth-pulp were recorded epidurally from the SI cortex of rabbits anesthetized with urethane and chloralose. It was found that nociceptive components of the evoked potential consisted of P1 and P2 wavelets with a relative stable peak latency of 22.5 +/- 1.2 ms and 66.1 +/- 1.9 ms respectively. Higher intensity of tooth pulp stimulation was required for appearance of P2 than P1. Diazepam, a non-analgesic sedative, reduced P1 but not P2 amplitude. On the contrary, dolantin, an analgesic, suppressed P2 but showed no significant influence on P1. The results suggest that P2, but not P1 might be related to pain. The effects of l-tetrahydropalmatine (1-THP) and electroacupuncture on P2 were observed on 12 animals. The results showed that both iv l-THP 8mg/kg and electroacupuncture brought forth a decrease in P2 amplitude by 40.3 +/- 14% and 59.3 +/- 10% respectively, while electroacupuncture combined with l-THP produce a further decrease in P2 amplitude by 92.8 +/- 7%. Furthermore, the inhibitory periods of P2 amplitude were significantly prolonged after electroacupuncture combined with l-THP. The results indicated that l-THP enhanced the suppression of P2 by electroacupuncture.

Effects of four dopamine agonists on l-tetrahydropalmatine-induced analgesia and electroacupuncture analgesia in rabbits

The effects of icv 4 dopamine (DA) agonists on analgesia caused by iv l-tetrahydropalmatine (THP) 8 mg/kg or by electro-acupuncture (EA) were studied by using the potassium iontophoretic dolorimetry in rabbits. The results showed that both THP-induced analgesia and EA analgesia were markedly attenuated by icv of DA or apomorphine (Apo), 2 mixed D1/D2 agonists. Similar results were obtained when SKF-38393, a selective D1 agonist, was applied. On the contrary, quinpirole hydrochloride (Qui), a selective D2 agonist, was found to enhance the analgesic action of THP or EA. However, DA, Apo, SKF-38393 or Qui per se did not influence the baseline pain threshold. All these observations indicate that functional alterations in DA receptor activities may be involved in THP-induced analgesia and EA analgesia, in which D1 and D2 subtype receptors exert different roles.

[Potentiation of electroacupuncture analgesia by l-tetrahydropalmatine and its analogues in rabbits]

l-Tetrahydropalmatine (l-THP), tetrahydroberberine (THB) and l-stepholidine (l-SPD) are the homologues of tetrahydroproto berberines and have a common antagonistic effect to central dopamine receptors. In the present experiment, the potassium iontophoretic dolorimetry was used to determine the pain threshold of rabbits. Unilateral "Hegu" point (the dorsum of the front paw, between 1st and 2nd metacarpals) and "Waiguan" point (the dorsum of the foreleg, between radius and ulna, 2 cm above the wrist joint) of each rabbit were electrically needled. The effects of iv l-THP 8 mg/kg, THB 16 mg/kg or l-SPD 4 mg/kg on electroacupuncture analgesia were investigated. The experimental results indicated that these 3 agents enhanced the potency of electroacupuncture analgesia and prolonged the duration as well. This investigation gives the evidence that the drug possessing antagonistic effect to central dopamine receptors could be used as a synergist of acupuncture analgesia.

Trace element content in drinking water of nasopharyngeal carcinoma patients

Chinese in the Xiangxi region of Hunan province in China have a high incidence of nasopharyngeal carcinoma (NPC). For analyzing the relation between NPC and trace elements, the concentrations of 7 trace elements in drinking water (well water) of high- and low-incidence areas were measured (75 samples). The results showed that the concentrations of Ni, Zn and Cd in drinking water of high-incidence areas were significantly higher than those in low-incidence areas. Especially, the Ni level in drinking water had a significant positive correlation with NPC mortality. These observations are consistent with earlier studies. We also found a highly positive correlation between Ni/pH value in drinking water and NPC mortality. This suggests that only considering the ion concentration in drinking water is not enough, we should also pay attention to the pH of the drinking water when we study the relation between NPC and trace elements. Because the pH of the medium can strongly affect trace element chemical characteristics and its metabolic state in living systems, the M/pH (M, metal concentration) may be an important factor worthy of further research.