[Comparison between therapeutic effects of transcutaneous electrical nerve stimulation with the frequency of 2 Hz and 100 Hz on Chronic inflammatory pain in rats]

OBJECTIVE

To observe the effects of repeated transcutaneous nerve stimulation (TENS) with low frequency (2 Hz) and high frequency (100 Hz) on the chronic inflammatory pain.

METHODS

The complete Freund's adjuvant was used to make the monoadjuvant arthritis as a chronic inflammatory pain model. The model animals were divided into 3 groups, the 100 Hz TENS group, the 2 Hz TENS group and the control group. The percentage increase of body weight, circumference of ankle, score of flexion pain test and score of extension pain test were used to evaluate the therapeutic effect of TENS.

RESULTS

(1) Body weight increasing rate in the 100 Hz TENS group was markedly higher than that in the 2 Hz TENS group and the control group. (2) Circumference of rats' ankle in the 100 Hz TENS group was smaller than that in the 2 Hz TENS and the control group. (3) Repeated 100 Hz TENS showed more effective on pain relief than that of 2 Hz TENS.

CONCLUSION

TENS has therapeutic effects on chronic inflammatory pain in rats, and different frequencies yielded different results.

[The molecular mechanism of high glucose-induced insulin resistance in 3T3-L1 adipocytes]

We investigated the cellular effect of high glucose using 3T3-L1 adipocytes on glucose transport activity, the expression of insulin signaling proteins and IRS1 tyrosine phosphorylation. Results showed that adipocytes treated with different high glucose (10, 15 and 25 mmol.L-1) for 24 hours showed to impair the basal and insulin-induced increase in glucose uptake in a dose-dependent manner and decreased significantly IRS1 tyrosine phosphorylation. High concentration of glucose produced opposite effects on IRS1 and IRS2: down-regulated IRS1 protein expression level and tightly up-regulated IRS2 contents. p85 and PKB were unaffected. Chronic exposure to high glucose can inhibit glucose uptake and induce insulin resistance. The mechanism may be involved in affecting the expression of insulin signaling peptides and tyrosine phosphorylation.

Receptor subtype-specific pronociceptive and analgesic actions of galanin in the spinal cord: selective actions via GalR1 and GalR2 receptors

Galanin is a 29-aa neuropeptide with a complex role in pain processing. Several galanin receptor subtypes are present in dorsal root ganglia and spinal cord with a differential distribution. Here, we describe a generation of a specific galanin R2 (GalR2) agonist, AR-M1896, and its application in studies of a rat neuropathic pain model (Bennett). The results show that in normal rats mechanical and cold allodynia of the hindpaw are induced after intrathecal infusion of low-dose galanin (25 ng per 0.5 microl/h). The same effect is seen with equimolar doses of AR-M1896 or AR-M961, an agonist both at GalR1 and GalR2 receptors. In allodynic Bennett model rats, the mechanical threshold increased dose-dependently after intrathecal injection of a high dose of AR-M961, whereas no effect was observed in the control or AR-M1896 group. No effect of either of the two compounds was observed in nonallodynic Bennett model rats. These data indicate that a low dose of galanin has a nociceptive role at the spinal cord level mediated by GalR2 receptors, whereas the antiallodynic effect of high-dose galanin on neuropathic pain is mediated by the GalR1 receptors. Thus, a selective GalR1 agonist may be used to treat neuropathic pain.

On-column amperometric detection of ofloxacin and pasiniazid in urine by capillary electrophoresis with an improved fractured joint and small detection cell

An improved high-voltage electric field isolating joint and small detection cell have been carefully designed and fabricated. The joint possesses short steady time, high electric conductance efficiency and high performance. The cell is convenient to install and remove the capillaries with and without the joint, as well as to fix, adjust and insert the microelectrode into the detection capillary. Using the joint and the cell, an analytical method for determination of ofloxacin (Oflx) and pasiniazid (Ipa) in urine by capillary electrophoresis with on-column amperometric detection was developed. The calibration lines were linear in the range of 10-100 mg l-1 of Oflx and 1.0-50 mg l-1 of Ipa, respectively. The detection limits were 8.5 mg l-1 of Oflx and 0.80 mg l-1 of Ipa. Their recovery ranged from 101 to 104%. The accuracy and intra-day and inter-day reproducibility of Oflx and Ipa were determined with satisfactory results. This method was successfully used for determining Oflx and Ipa in human urine.

A mechanism for exon skipping caused by nonsense or missense mutations in BRCA1 and other genes

Point mutations can generate defective and sometimes harmful proteins. The nonsense-mediated mRNA decay (NMD) pathway minimizes the potential damage caused by nonsense mutations. In-frame nonsense codons located at a minimum distance upstream of the last exon-exon junction are recognized as premature termination codons (PTCs), targeting the mRNA for degradation. Some nonsense mutations cause skipping of one or more exons, presumably during pre-mRNA splicing in the nucleus; this phenomenon is termed nonsense-mediated altered splicing (NAS), and its underlying mechanism is unclear. By analyzing NAS in BRCA1, we show here that inappropriate exon skipping can be reproduced in vitro, and results from disruption of a splicing enhancer in the coding sequence. Enhancers can be disrupted by single nonsense, missense and translationally silent point mutations, without recognition of an open reading frame as such. These results argue against a nuclear reading-frame scanning mechanism for NAS. Coding-region single-nucleotide polymorphisms (cSNPs) within exonic splicing enhancers or silencers may affect the patterns or efficiency of mRNA splicing, which may in turn cause phenotypic variability and variable penetrance of mutations elsewhere in a gene.

[Studies of the mixoploid variation in banana micropropagated plants]

A special type of variation--the mixoploid variation, which had a great effect on the variation in the production of banana vitroplants, was reported for the first time. By means of examining chromosome, isozymes (EST, MDH, POX) and endogenous hormones (iPAs, IAA), the varied characters of the mixoploid varianties during the propagation in vitro when cultured as explant were investigated. The rate of the chromosome aberration in cells was characterized by starting at a much higher level and rising more rapidly in the preceding 15 subcultures as compared with the control. The rate of the isozyme variation was higher obviously than that of the control. The plantlets cloned in vitro from the mixoploid variant were also studied. The experiment showed that both the variant rates of chromosome and phenotype rose obviously. The mixoploid variant can cause the rate of variation to rise during the micropropagation.

Erhaia (Gastropoda: Rissooidea): phylogenetic relationships and the question of Paragonimus coevolution in Asia

The human lung fluke Paragonimus is transmitted by gastropod taxa of two superfamilies: Ceritheoidea and Rissooidea. The question whether or not Paragonimus shows the same specificity of host-parasite coevolved relationship as the human blood fluke Schistosoma was inspired by the finding of two sympatric snail species as hosts for Paragonimus skrjabini in Fujian Province, China: Gammatricula and Erhaia. The former species can clearly be classified as Pomatiopsidae: Triculinae. The latter has previously been classified as Pomatiopsidae: Pomatiopsinae. However, this classification based on anatomical characteristics is uncertain. In order to obtain a robust phylogenetic hypothesis for Erhaia, we have studied three gene fragments from this taxon as well as from twelve related taxa. The data show that the species involved represent four families: Pomatiopsidae, Hydrobiidae, Cochliopidae (here raised to family status), and Amnicolidae. Erhaia fits securely into the Amnicolidae. This indicates that P. skrjabini has not coevolved with snail lineages. However, P. skrjabini has so far only been reported from rissooidean snails, whereas members of the Paragonimus westermani complex have only been found in ceritheoidean snails. The implication is that there is a host specificity on the superfamily level. However, Asian freshwater species of the Ceritheoidea and Rissooidea usually are not sympatric and often prefer different habitats. It is therefore possible that ecological niche partitioning plays the primary role for Paragonimus evolution.

Decreased GDNF mRNA expression in dorsal spinal cord of unilateral arthritic rat

It is now well established that nerve growth factor (NGF) plays a key role in inflammation-induced hyperalgesia. It was also reported that brain derived neurotrophic factor (BDNF), another member of neurotrophins, contributed to the pain pathway as a neurotransmitter in the CNS. The present work demonstrated a down-regulation of glial cell line-derived neurotrophic factor (GDNF) mRNA expression in dorsal spinal cord in complete Freund's adjuvant-induced unilateral arthritic rats serving as a chronic pain model. The fast occurring and long lasting down-regulations suggest that GDNF might contribute to pain pathway in a way different from neurotrophins and might play a role in the maintenance of chronic pain status.

On-column amperometric detection in capillary electrophoresis with an improved high-voltage electric field decoupler

An improved fabrication method for a decoupler for on-column amperometric detection in capillary electrophoresis (CE) is described. The decoupler is fabricated by etching one side-wall of the capillary with hydrofluoric acid after the polymer coating had been etched by laser, then the etched hole is sealed with adhesive. The steady time, electric conductivity efficiency and performance are investigated. On-column amperometric detection by CE of para-substituted phenols was carried out by coupling with a carbon-fiber microelectrode (10-microm diameter) and a practical small electrochemical detection cell.

Exonic splicing enhancer motif recognized by human SC35 under splicing conditions

Exonic splicing enhancers (ESEs) are important cis elements required for exon inclusion. Using an in vitro functional selection and amplification procedure, we have identified a novel ESE motif recognized by the human SR protein SC35 under splicing conditions. The selected sequences are functional and specific: they promote splicing in nuclear extract or in S100 extract complemented by SC35 but not by SF2/ASF. They can also function in a different exonic context from the one used for the selection procedure. The selected sequences share one or two close matches to a short and highly degenerate octamer consensus, GRYYcSYR. A score matrix was generated from the selected sequences according to the nucleotide frequency at each position of their best match to the consensus motif. The SC35 score matrix, along with our previously reported SF2/ASF score matrix, was used to search the sequences of two well-characterized splicing substrates derived from the mouse immunoglobulin M (IgM) and human immunodeficiency virus tat genes. Multiple SC35 high-score motifs, but only two widely separated SF2/ASF motifs, were found in the IgM C4 exon, which can be spliced in S100 extract complemented by SC35. In contrast, multiple high-score motifs for both SF2/ASF and SC35 were found in a variant of the Tat T3 exon (lacking an SC35-specific silencer) whose splicing can be complemented by either SF2/ASF or SC35. The motif score matrix can help locate SC35-specific enhancers in natural exon sequences.

Evidence for the function of an exonic splicing enhancer after the first catalytic step of pre-mRNA splicing

Exonic splicing enhancers (ESEs) activate pre-mRNA splicing by promoting the use of the flanking splice sites. They are recognized by members of the serine/arginine-rich (SR) family of proteins, such as splicing factor 2/alternative splicing factor (SF2/ASF), which recruit basal splicing factors to form the initial complexes during spliceosome assembly. The in vitro splicing kinetics of an ESE-dependent IgM pre-mRNA suggested that an SF2/ASF-specific ESE has additional functions later in the splicing reaction, after the completion of the first catalytic step. A bimolecular exon ligation assay, which physically uncouples the first and second catalytic steps of splicing in a trans-splicing reaction, was adapted to test the function of the ESE after the first step. A 3' exon containing the SF2/ASF-specific ESE underwent bimolecular exon ligation, whereas 3' exons without the ESE or with control sequences did not. The ESE-dependent trans-splicing reaction occurred after inactivation of U1 or U2 small nuclear ribonucleoprotein particles, compatible with a functional assay for events after the first step of splicing. The ESE-dependent step appears to take place before the ATP-independent part of the second catalytic step. Bimolecular exon ligation also occurred in an S100 cytosolic extract, requiring both the SF2/ASF-dependent ESE and complementation with SF2/ASF. These data suggest that some ESEs can act late in the splicing reaction, together with appropriate SR proteins, to enhance the second catalytic step of splicing.

Nocistatin reverses the effect of orphanin FQ/nociceptin in antagonizing morphine analgesia

Nocistatin is a recently characterized neuropeptide derived from the preprohormone containing nociceptin (Orphanin FQ, OFQ). Nocistatin was reported to antagonize OFQ induced allodynia, hyperalgesia and prostaglandin E2-elicited pain responses. The aim of the present study was to determine whether nocistatin, injected intracerebroventricularly (i.c.v.), would reverse the anti-morphine effect of OFQ in rats using the tail-flick latency (TFL) as the nociceptive index. I.c.v. injection of nocistatin at doses of 0.005, 0.05, 0.5, 5, 50, and 500 ng produced no significant changes in the basal TFL, nor did it affect morphine analgesia. However, it significantly reversed the antagonistic effect of OFQ on morphine analgesia when co-injected i.c.v. at doses of 0.05, 0.5, 5, 50 and 500 ng per rat with OFQ. The dose-response curve was bell-shaped and the most effective dose was 0.5 ng. The results suggest that nocistatin can reverse the anti-morphine effect of OFQ in rat brain.

[Repeated 100 Hz TENS for the treatment of chronic inflammatory pain in rats: optimal parameters and possible neuro-chemical mechanisms]

AIMS

To establish a reliable animal model of chronic arthritic inflammatory pain, to find the optimal parameters and appropriate intervals of repeated 100 Hz transcutaneous electrical nerve stimulation (TENS) for the treatment of the chronic arthritic pain, and to explore the possible central neurochemical mechanisms.

THE RESULTS

(1) Injection of water-in-oil type complete Freund's adjuvant into the tibio-tarsal joint of the rat produced a reliable, reproducible monoarthritic model. (2) The interval between 2 sessions of stimulations and the intensity of stimulation were important factors determining the therapeutic effects of repeated 100 Hz TENS on both acute and stable period of monoarthritis. (a) For acute period of monoarthritis, the optimal frequency is twice a week, while in the stable period, once a week seems better. (b) The effects of TENS in three intensities: the weaker stimulation was found to produce better results. (3) In the period from 2 to 9 weeks, the levels of spinal release of SP-ir in the TENS group were lower than the control group. This may constitute one of the possible neuro-chemical mechanisms underlying the therapeutic effects of multiple TENS treatment. (4) In both acute and stable period of adjuvant-induced monoarthritis, intrathecal microinjection of Nor-BNI produced dose-dependent increase of arthritic flexion pain scores (i.e. hyperalgesia), suggesting that spinal dynorphin/kappa system plays a role in suppressing arthritic pain.

A reproducible, simple, and sensitive high-performance capillary electrophoresis method for simultaneous determination of capreomycin, ofloxacin and pasiniazide in urine

Separation and determination of capreomycin (Cp), ofloxacin (Oflx) and pasiniazide (Ipa) in urine by high-performance capillary electrophoresis (HPCE) with 280 nm detection have been studied systematically. The calibration lines were linear in the range of 0.5 approximately 50 mg 1(-1), and the detection limits (S/N = 3) were 0.15, 0.20 and 0.10 mg 1(-1) for Cp, Oflx and Ipa, respectively. The recoveries for these materials from urine were higher than 93.5%. The accuracy and intra- and inter- day reproducibility of Cp, Oflx and Ipa were determined with satisfactory results. This method was successfully used for determining Cp. Oflx and Ipa in human urine.

Identification of functional exonic splicing enhancer motifs recognized by individual SR proteins

Using an in vitro randomization and functional selection procedure, we have identified three novel classes of exonic splicing enhancers (ESEs) recognized by human SF2/ASF, SRp40, and SRp55, respectively. These ESEs are functional in splicing and are highly specific. For SF2/ASF and SRp55, in most cases, only the cognate SR protein can efficiently recognize an ESE and activate splicing. In contrast, the SRp40-selected ESEs can function with either SRp40 or SRp55, but not with SF2/ASF. UV cross-linking/competition and immunoprecipitation experiments showed that SR proteins recognize their cognate ESEs in nuclear extract by direct and specific binding. A motif search algorithm was used to derive consensus sequences for ESEs recognized by these SR proteins. Each SR protein yielded a distinct 5- to 7-nucleotide degenerate consensus. These three consensus sequences occur at higher frequencies in exons than in introns and may thus help define exon-intron boundaries. They occur in clusters within regions corresponding to naturally occurring, mapped ESEs. We conclude that a remarkably diverse set of sequences can function as ESEs. The degeneracy of these motifs is consistent with the fact that exonic enhancers evolved within extremely diverse protein coding sequences and are recognized by a small number of SR proteins that bind RNA with limited sequence specificity.

Comparison of high-performance capillary electrophoresis and liquid chromatography on analysis of zinc 5-aminosalicylate dihydrate and related materials

Separation and determination of zinc 5-aminosalicylate dihydrate (ZASA) and related materials by high-performance capillary electrophoresis (HPCE) and liquid chromatography (HPLC) have been studied systematically. The R.S.D. of peak time and area and detection limits of materials were lower in HPLC compared to HPCE. HPCE and HPLC were used for determining ZASA and related materials in crude and treated ZASA using acid and heat, and similar results with both techniques showed the principal impurities in the crude ZASA were 5-aminosalicylic acid (ASA) and salicylic acid (SA), the compounds from ZASA decomposing under conditions of acid and heat were ASA, p-aminophenol and 5-benzeneazosalicylic acid.

Comparison of high performance capillary electrophoresis and liquid chromatography for the determination of acyclovir and guanine in pharmaceuticals and urine

High-performance capillary electrophoresis (HPCE) and high-performance liquid chromatography (HPLC) were developed and applied to the determination of acyclovir (ACV) and guanine (G) in pharmaceuticals. The comparison study showed that two methods gave comparable results in linear range, recovery and reproducibility. HPCE was used for the determination of ACV and G in urine; the recovery was better than 81.3% and the RSD was less than 4.4%.

Mapping of branchpoint nucleotides in mutant pre-mRNAs expressed in plant cells

Pre-mRNA encoding rubisco activase in the Arabidopsis thaliana mutant rca contains a GU to AU change at the 5' splice site of intron 3 and this mutation results in accumulation of splicing intermediates bearing an incompletely processed intron. It has been demonstrated that one of the intermediates contains intron 3 in the form of a lariat and the branchpoint nucleotide has been mapped to the A residue at position -32 forming part of the sequence UUGAU. Analysis of a similar GU to AU 5' splice site mutation, present in a synthetic pre-mRNA context expressed in transfected protoplasts of Nicotiana plumbaginifolia, also suggests formation of lariats with branching occurring at A-31. A small fraction (approximately 10%) of this mutant pre-mRNA also underwent the second step of splicing. In addition to the consensus AG, an AU dinucleotide was used as splicing acceptor.

Characterization of intronic uridine-rich sequence elements acting as possible targets for nuclear proteins during pre-mRNA splicing in Nicotiana plumbaginifolia

Introns of nuclear pre-mRNAs in dicotyledonous plants, unlike introns in vertebrates or yeast, are distinctly rich in A+U nucleotides and this feature is essential for their processing. In order to define more precisely sequence elements important for intron recognition in plants, we investigated the effects of short insertions, either U-rich or A-rich, on splicing of synthetic introns in transfected protoplast of Nicotiana plumbaginifolia. It was found that insertions of U-rich (sequence UUUUUAU) but not A-rich (AUAAAAA) segments can activate splicing of a GC-rich synthetic infron, and that U-rich segments, or multimers thereof, can function irrespective of the site of insertion within the intron. Insertions of multiple U-rich segments, either at the same or different locations, generally had an additive, stimulatory effect on splicing. Mutational analysis showed that replacement of one or two U residues in the UUUUUAU sequence with A or C residues had only a small effect on splicing, but replacement with G residues was strongly inhibitory. Proteins that interact with fragments of natural and synthetic pre-mRNAs in vitro were identified in nuclear extracts of N.plumbaginifolia by UV cross- linking. The profile of cross-linked plant proteins was considerably less complex than that obtained with a HeLa cell nuclear extract. Two major cross-linkable plant proteins had apparent molecular mass of 50 and 54 kDa and showed affinity for oligouridilates present in synGC introns or for poly(U).

Some altered concentrations of elements in semen of workers exposed to trinitrotoluene

OBJECTIVES

A cross sectional study was performed to find the concentrations of elements contained in the semen of workers exposed to trinitrotoluene (TNT).

SUBJECTS AND METHODS

Semen of exposed workers in two TNT plants located in He-Nan Province in 1992 were examined.

RESULTS

The average TNT concentrations in the workplace, except the packing site, were found to have exceeded the maximal allowable concentration (MAC, 1 mg/m3); skin contaminations of male workers exposed to TNT were higher after a shift than in controls, and correlated with the total blood concentrations of TNT, 4-amino-2, 6-dinitrotoluene (4A), and 2-amino-4, 6-dinitrotoluene (2A). Cu, Zn, Na, Mg, and Se concentrations were significantly decreased, but K, Ca, Co, Mn and Li contents were not significantly changed in the semen of workers exposed to TNT. Compared with the control group, the percentage of liquifying time of semen, the sperm malformation incidence, and viability in the men exposed to TNT were all significantly changed.

CONCLUSIONS

Men exposed to TNT have decreased concentrations of some elements is semen and altered semen physiology.

Effects of secondary structure on pre-mRNA splicing: hairpins sequestering the 5' but not the 3' splice site inhibit intron processing in Nicotiana plumbaginifolia

We have performed a systematic study of the effect of artificial hairpins on pre-mRNA splicing in protoplasts of a dicot plant, Nicotiana plumbaginifolia. Hairpins with a potential to form 18 or 24 bp stems strongly inhibit splicing when they sequester the 5' splice site or are placed in the middle of short introns. However, similar 24 bp hairpins sequestering the 3' splice site do not prevent this site from being used as an acceptor. Utilization of the stem-located 3' site requires that the base of the stem is separated from the upstream 5' splice site by a minimum of approximately 45 nucleotides and that another 'helper' 3' splice site is present downstream of the stem. The results indicate that the spliceosome or factors associated with it may have a potential to unfold secondary structure present in the downstream portion of the intron, prior to or at the step of the 3' splice site selection. The finding that the helper 3' site is required for utilization of the stem-located acceptor confirms and extends previous observations, obtained with HeLa cell in vitro splicing systems, indicating that the 3' splice site may be recognized at least twice during spliceosome assembly.

Enhancement of the intestinal absorption of a cyclosporine derivative by milk fat globule membrane

A cyclosporine derivative, dihydrocyclosporine D, was used for the evaluation of milk fat globule membrane (MFGM) as an emulsifier of lipophilic cyclopeptides. As compared with olive oil formulation, MFGM emulsion significantly enhanced the blood and lymphatic fluid concentrations of the cyclosporine derivative after intraduodenal dosing in rats. Thus, it was suggested that MFGM can be used as an intestinal absorption enhancer of cyclosporines.