Motor unit properties after operant conditioning of rat H-reflex

Operant conditioning of the H-reflex produces plasticity at several sites in the spinal cord, including the motoneuron. This study assessed whether this spinal cord plasticity is accompanied by changes in motor unit contractile properties. Thirty-one adult male Sprague-Dawley rats implanted for chronic recording of triceps surae electromyographic activity and H-reflex elicitation were exposed for at least 40 days to HRup or HRdown training, in which reward occurred when the H-reflex was greater than (12 HRup rats) or less than (12 HRdown rats) a criterion value, or continued under the control mode in which the H-reflex was simply measured (7 HRcon rats). At the end of H-reflex data collection, rats were anesthetized and the contractile properties of 797 single triceps surae motor units activated by intraaxonal (or intramyelin) current injection were determined. Motor units were classified as S, FR, Fint, or FF on the basis of sag and fatigue properties. Maximum tetanic force and twitch contraction time were also measured. HRdown rats exhibited a significant increase in the fatigue index of fast-twitch motor units. This resulted in a significant decrease in the percentage of Fint motor units and a significant increase in that of FR motor units. HRup conditioning had no effect on fatigue index. Neither HRup nor HRdown conditioning affected maximum tetanic force or twitch contraction time. These data are consistent with the hypothesis that conditioning mode-specific change in motoneuron firing patterns causes activity-dependent change in muscle properties.

Molecular cloning and functional identification of (+)-delta-cadinene-8-hydroxylase, a cytochrome P450 mono-oxygenase (CYP706B1) of cotton sesquiterpene biosynthesis

In cotton, gossypol and related sesquiterpene aldehydes are present in the glands of aerial tissues and in epidermal cells of roots. A cytochrome P450 was found to be expressed in aerial tissues of glanded cotton cultivars, but not or at an extremely low level in the aerial tissues of a glandless cultivar. Its cDNA was then isolated from Gossypium arboreum L. After expression in Saccharomyces cerevisiae, the P450 was found to catalyse the hydroxylation of (+)-delta-cadinene, forming 8-hydroxy-(+)-delta-cadinene. This P450 mono-oxygenase has been classified as CYP706B1, and is the first member of the CYP706 family for which a function has been determined. Sesquiterpene aldehydes and CYP706B1 transcripts were detected in roots of both the glanded and glandless cultivars and in aerial tissues of the glanded cultivar. In suspension cultured cells of G. arboreum, elicitors prepared from the phytopathogenic fungus Verticillium dahliae caused a dramatic induction of CYP706B1 expression. The expression pattern of CYP706B1 and the position at which it hydroxylates (+)-delta-cadinene suggest that it catalyses an early step in gossypol biosynthesis. Southern blotting revealed a single copy of CYP706B1 in the genome of G. arboreum. CYP706B1 holds good potential for manipulation of gossypol levels in cottonseed via genetic engineering.

[Determination of bambuterol in human plasma by liquid chromatography-electrospray tandem mass spectrometry: application to pharmacokinetic study]

AIM

To develop a sensitive, specific and accurate method for quantifying bambuterol in human plasma and to study pharmacokinetics of bambuterol in male healthy Chinese.

METHODS

Plasma samples were prepared based on a simple liquid-liquid extraction. The extracted samples were analyzed on liquid chromatography using a Zorbax SB C18 column interfaced with a triple quadrupole tandem mass spectrometer and detected by use of selected reaction monitoring mode.

RESULTS

The linear calibration curves were obtained in the concentration range of 0.05-4.0 ng.mL-1. The limit of quantification was 0.05 ng.mL-1. The intra- and inter-run precision was measured to be below 7%. The inter-run accuracy was less than 8% for the analyte. After an oral administration of 10 mg bambuterol hydrochloride to 18 healthy Chinese volunteers the main pharmacokinetic parameters of bambuterol were as follows: Tmax was (2.3 +/- 1.3) h; Cmax was (3.95 +/- 2.20) ng.mL-1; T1/2 was (11.4 +/- 6.1) h and AUC0-t was (26.85 +/- 11.77) ng.h.mL-1.

CONCLUSION

The method is shown to be accurate, robust and convenient, and suitable for pharmacokinetic studies of bambuterol. It was found that there was marked inter-individual difference in the pharmacokinetics of bambuterol in Chinese volunteers after a single oral dose, which may be attributed to the difference of activity of cholinesterase, an enzyme catalyzing bambuterol metabolism.

[Rapid analysis of terbutaline by combined solid phase extraction/liquid chromatography tandem mass spectrometry]

AIM

To develop a liquid chromatography-electrospray ionization tandem mass spectrometry method for rapid analysis of terbutaline at level of 50 pg.mL-1 in human plasma.

METHODS

Samples containing terbutaline and salbutamol (internal standard, IS) were extracted using C18 solid-phase extraction cartridges, followed by liquid chromatographic separation and mass spectrometric detection. The mobile phase consisted of acetonitrile-water-formic acid (20:80:1), at a flow-rate of 0.4 mL.min-1. Selected reaction monitoring with mass transitions m/z 226-->151 and m/z 240-->148 were used for terbutaline and IS, respectively.

RESULTS

The chromatographic analysis time for each sample was approximately 3.8 min. The assay was linear from 0.05 to 8.0 ng.mL-1. The between-run precision and accuracy of the quality controls (QCs, 0.1, 0.4 and 4.0 ng.mL-1) were characterized by relative standard deviation (RSD) of 2.5% to 7.1% and relative errors of -3.1% to 5.7%, respectively. The within-run precision of QCs was characterized by RSD of 4.2% to 6.6%. This method was applied to the analysis of samples taken up to 60 h after oral administration of 10 mg bambuterol in healthy volunteers.

CONCLUSION

The method is shown to be suitable for clinical investigation of terbutaline pharmacokinetics, which offers advantages of specificity, speed, and greater sensitivity over previously reported methods.

Ricin A-chain inhibitors resembling the oxacarbenium ion transition state

Ricin toxin A-chain (RTA) is expressed by the castor bean plant and is among the most potent mammalian toxins. Upon activation in the cytosol, RTA depurinates a single adenine from position 4324 of rat 28S ribosomal RNA, causing inactivation of ribosomes by preventing the binding of elongation factors. Kinetic isotope effect studies have established that RTA operates via a D(N)*A(N) mechanism involving an oxacarbenium ion intermediate with bound adenine [Chen, X.-Y., Berti, P. J., and Schramm, V. L. (2000) J. Am. Chem. Soc. 122, 1609-1617]. On the basis of this information, stem-loop RNA molecules were chemically synthesized, incorporating structural features of the oxacarbenium ion-like transition state. A 10-base RNA stem-loop incorporating (1S)-1-(9-deazaadenin-9-yl)-1,4-dideoxy-1,4-imino-D-ribitol at the depurination site binds four times better (0.57 microM) than the 10-base RNA stem-loop with adenosine at the depurination site (2.2 microM). A 10-base RNA stem-loop with 1,2-dideoxyribitol [(2R,3S)-2-(hydroxymethyl)-3-hydroxytetrahydrofuran] at the depurination site binds with a Kd of 3.2 microM and tightens to 0.75 microM in the presence of 9-deazaadenine. A similar RNA stem-loop with 1,4-dideoxy-1,4-imino-D-ribitol at the depurination site binds with a K(d) of 1.3 microM and improves to 0.65 micro;M with 9-deazaadenine added. When (3S,4R)-4-hydroxy-3-(hydroxymethyl)pyrrolidine was incorporated at the depurination site of a 14-base RNA stem-loop, the Kd was 0.48 microM. Addition of 9-deazaadenine tightens the binding to 0.10 microM whereas added adenine increases the affinity to 12 nM. The results of this study are consistent with the unusual dissociative D(N)*A(N) mechanism determined for RTA. Knowledge of this intermediate has led to the design and synthesis of the highest affinity inhibitor reported for the catalytic site of RTA.

Effect of sodium dimercaptopropanesulfonate on antagonism of tetramethylenedisulphotetramine to GABA receptor

AIM

To study effects of sodium dimercaptopropanesulfonate (DMPS) on the antagonism of tetramethylenedisulphotetramine (TETS) to gamma-aminobutyric acid (GABA) receptor.

METHODS

Acute toxicity experiments were conducted to observe the effects of DMPS and TETS on mice. Contents of free amino acids in mouse brain were determined with automatic analyzer for amino acids. Autoradiography was used to observe the [3H]GABA bindings in the rat brain slices under different conditions.

RESULTS

After icv and ip DMPS, the number of mice experiencing convulsions reduced from 20 in control group to 4 and 2 respectively in TETS poisoned mice. The content of GABA was altered in DMPS control group and TETS control group compared with DMPS protection group and NS control group [micromol/g: (2.09 +/- 0.05) and (2.67 +/- 0.15) vs (2.40 +/- 0.10 (micromol/g)) and (2.41 +/- 0.21)]; the content of glutamic acid was (12.3 +/- 1.2), (12.0 +/- 0.8), (10.2 +/- 0.6), and (11.8 +/- 1.0) micromol/g in NS control group, DMPS control group, TETS control group, and DMPS protection group, respectively. The OD value of autoradiograms decreased in TETS group compared with buffer control group in cortex, hippocampus, diencephalon, and brainstem [(0.084 +/- 0.008), (0.081 +/- 0.009), (0.094 +/- 0.006) and (0.081 +/- 0.006), vs (0.102 +/- 0.003), (0.109 +/- 0.005), (0.128 +/- 0.007), and (0.125 +/- 0.008), respectively]. OD value was maintained or higher than the normal level in DMPS+TETS group in the four brain areas [(0.116 +/- 0.008), (0.125 +/- 0.011), (0.129 +/- 0.005), and (0.128 +/- 0.010) vs (0.102 +/- 0.003), (0.109 +/- 0.005), (0.128 +/- 0.007), and (0.125 +/- 0.008), respectively].

CONCLUSION

The inhibitory effects of DMPS on the antagonism of TETS to GABA receptor are due to the increase in the GABA binding to its receptors in brain caused by DMPS

Comparison of precancerous conditions: atrophy and intestinal metaplasia in Helicobacter pylori gastritis among Chinese and Dutch patients

AIM-Atrophy and intestinal metaplasia (IM) as precancerous conditions consistently begin in the antrum and are most severe along the lesser curvature. The aim of this study was to investigate discrepancies in the prevalence, the severity of atrophy, and IM in antral mucosa of Helicobacter pylori infected gastritis and difference in age of onset among Chinese and Dutch patients. METHODS-Two hundred and sixty five Chinese patients and 261 Dutch patients with H pylori infection were enrolled. The degrees of atrophy and IM were graded according to the updated Sydney system. RESULTS-The overall prevalences of atrophy and IM were lower in Dutch patients (42% and 26%, respectively) than in Chinese patients (52% and 32%, respectively). Only the difference in atrophy reached significance (p = 0.028). However, in both Chinese and Dutch patients, the degrees of atrophy and IM were low and severe degrees were rare. The mean ages of Chinese and Dutch patients with atrophy and IM were higher than those without atrophy and IM (with atrophy (Chinese patients): mean, 42.12; SD, 9.80; with IM (Chinese patients): mean, 42.56; SD, 9.96; with atrophy (Dutch patients): mean, 55.16; SD, 12.20; with IM (Dutch patients): mean, 57.79; SD, 11.13; without atrophy (Chinese patients): mean, 39.71; SD, 10.16; without IM (Chinese patients): mean, 40.19; SD, 9.99; without atrophy (Dutch patients): mean, 45.70; SD, 12.44; without IM (Dutch patients): mean, 46.89; SD, 12.68). Atrophy and IM occurred earlier and were more severe in Chinese patients, with both reaching a peak value in patients over 60 years. CONCLUSIONS-There are geographical differences in the prevalence and severity of H pylori infected gastritis, in particular with respect to atrophy and IM, which suggests that infection with H pylori occurs earlier in life and has a higher prevalence in CHINA:

Time course of H-reflex conditioning in the rat

This study sought to define the course of operantly conditioned change in the rat soleus H-reflex and to determine whether, like H-reflex conditioning and spinal stretch reflex conditioning in the monkey, it develops in distinct phases. Data from 33 rats in which the right soleus H-reflex was trained up (i.e. HRup mode) and 38 in which it was trained down (i.e. HRdown mode) were averaged to define the courses of H-reflex increase and decrease. In HRup rats, the H-reflex showed a large phase I increase within the first 2 days followed by gradual phase II increase that continued for weeks. In HRdown rats, the H-reflex appeared to show a small phase I decrease and then showed a gradual phase II decrease over weeks. In combination with other recent work, the data suggest that H-reflex conditioning begins with a rapid mode-appropriate alteration in corticospinal tract influence over the spinal arc of the H-reflex, which causes phase I change, and that the continuation of this altered influence induces gradual spinal cord plasticity that is responsible for phase II change. The results further establish the similarity of H-reflex conditioning in primates and rats. Thus, they encourage efforts to produce a single coherent model of the phenomenon based on data from the two species and indicate the potential clinical relevance of the rat data.

Short-Term and medium-term effects of spinal cord tract transections on soleus H-reflex in freely moving rats

Spinal cord function is normally influenced by descending activity from supraspinal structures. When injury removes or distorts this influence, function changes and spasticity and other disabling problems eventually appear. Understanding how descending activity affects spinal cord function could lead to new means for inducing, guiding, and assessing recovery after injury. In this study, we investigated the short-term and medium-term effects of spinal cord bilateral dorsal column (DC), unilateral (ipsilateral) lateral column (LC), bilateral dorsal column ascending tract (DA), or bilateral dorsal column corticospinal tract (CST) transection at vertebral level T8-T9 on the soleus H-reflex in freely moving rats. Data were collected continuously for 10-20 days before and for 20-155 days after bilateral DC (13 rats), DA (10 rats), CST (eight rats), or ipsilateral LC (seven rats) transection. Histological examination showed that transections were 98(+/- 3 SD)% complete for DC rats, 80(+/- 20)% complete for LC rats, 91(+/- 13 SD)% complete for DA rats, and 95(+/-13)% complete for CST rats. LC, CST, and DA transections produced an immediate (i.e., first-day) increase in H-reflex amplitude. LC transection also produced a small decrease in background activity in the first few posttransection days. Other than this small decrease, none of the transections produced evidence for the phenomenon of spinal shock. For all transections, all measures returned to or neared pretransection values within 2 weeks. DA and LC transections were associated with modest increase in H-reflex amplitude 1-3 months after transection. These medium-term effects must be taken into account when assessing transection effects on operant conditioning of the H-reflex. At the same time, the results are consistent with other evidence that, while H-reflex rate dependence and H-reflex operant conditioning are sensitive measures of spinal cord injury, the H-reflex itself is not.

[Determination of amlodipine in human plasma by liquid chromatography-tandem mass spectrometry]

AIM

To develop a sensitive and specific LC/MS/MS method for determination of amlodipine in human plasma.

METHODS

Amlodipine and internal standard 4'-hydroxypropafenone were extracted from plasma using liquid-liquid extraction, then separated on a Zorbax C8 column. The mobile phase consisted of acetonitrile-water-formic acid (75:35:1), at a flow-rate of 0.4 mL.min-1. A Finnigan TSQ tandem mass spectrometer equipped with electrospray ionization source was used as detector and was operated in the positive ion mode. Selected reaction monitoring (SRM) using the precursor-->product ion combinations of m/z 409-->238 and m/z 358-->116 was used to quantify amlodipine and internal standard, respectively.

RESULTS

The linear calibration curves were obtained in the concentration range of 0.4-16.0 ng.mL-1. The limit of quantification was 0.4 ng.mL-1. Each plasma sample was chromatographed within 3.7 min. The method was successfully used in several pharmacokinetic studies for amlodipine. More than 1,500 plasma samples were assayed within two weeks.

CONCLUSION

The method is proved to be suitable for clinical investigation of amlodipine pharmacokinetics, which offers advantages of specificity, speed, and greater sensitivity over the previously reported methods.

Operant conditioning of rat H-reflex: effects on mean latency and duration

We are currently studying the mechanisms of operantly conditioned changes in the H-reflex in the rat. Primate data suggest that H-reflex decrease is due to a positive shift in motoneuron firing threshold and a small decrease in the monosynaptic excitatory postsynaptic potential (EPSP), and that increase might be due to change in group-I oligosynaptic (especially disynaptic) input. To further evaluate the possibility of conditioned change in oligosynaptic input, we compared the mean latency (i.e., the average latency of the entire H-reflex) and the duration of control (i.e., pre-conditioning) H-reflexes with those of H-reflexes after up-conditioning or down-conditioning. Up-conditioning was associated with small, statistically significant increases in H-reflex mean latency [+0.11+/-0.05 (+/-SE) ms] and duration (+0.32+/-0.16 ms). The mean latency of the H-reflex increase (i.e., the part added to the H-reflex by up-conditioning) was 0.28+/-0.14 (+/-SE) ms greater than that of the control H-reflex. Down-conditioning had no significant effect on mean latency or duration. While these results indicate that operant conditioning does not greatly change H-reflex mean latency or duration, the effects detected with up-conditioning are consistent with the hypothesis that decreased inhibition, or increased excitation, by homonymous and heteronymous group-I oligosynaptic input contributes to the H-reflex increase produced by up-conditioning. Several other mechanisms might also account for these small effects.

Operant conditioning of rat H-reflex affects motoneuron axonal conduction velocity

This study assessed the effects of operant conditioning of the H-reflex on motoneuron axonal conduction velocity in the rat. After measurement of the control H-reflex size, rats were either exposed for at least 40 days to the HRup or HRdown conditioning mode, in which reward occurred only if the soleus H-reflex was greater than (HRup mode) or less than (HRdown mode) a criterion or continued under the control condition (HRcon mode) in which the H-reflex was simply measured. We then measured axonal conduction velocity of triceps surae motor units of HRup, HRdown, and HRcon rats by stimulating the axon in the ventral root and recording from the tibial nerve. Conduction velocity was 8% less in successful HRdown rats than in HRcon rats (P=0.02). Conduction velocity in HRup rats and unsuccessful HRdown rats was not significantly different from that in HRcon rats. Since recording bypassed the intra-spinal portion of the motoneuron, the change was clearly in the axon. This decrease was similar to the 6% decrease previously found in successful HRdown monkeys. Unsuccessful HRdown rats and monkeys did not show this decrease. This result suggests that the mechanism of HRdown conditioning is similar in rats and monkeys and provides further support for the hypothesis that HRdown conditioning decreases motoneuron excitability by producing a positive shift in firing threshold. While traditional theories of learning emphasize synaptic plasticity, neuronal plasticity may also contribute to operantly conditioned behavioral changes.

[Preliminary study on apoptosis of human leukemic cells induced by bufalin]

OBJECTIVE

To study the mechanism of inhibiting actions of bufalin on human leukemic cells (HL60).

METHODS

HL60 cells were incubated with bufalin at different concentrations and growth inhibition was analyzed by trypan-blue staining. Cell apoptosis was evaluated by phase contrast microscopy, transmission eletron microscopy and agarose gel electrophoresis.

RESULTS

Bufalin remarkably inhibited the growth of HL60 cells. Apoptosis of HL60 cells could be effectively induced by bufalin at concentration of 0.01 mumol.L-1 or higher, showing the apoptotic changes in morphology, including cell shrinkage, chromatin agglutination and formation of apoptotic corpuscula; DNA cleavage was observed with agarose gel electrophoresis.

CONCLUSION

Bufalin can effectively induce apoptosis of HL60 cells, which is possibly one of the mechanisms for anti-cancer of bufalin.

Protective effect of gypenosides on DNA and RNA of rat neurons in cerebral ischemia-reperfusion injury

AIM

To observe the protective effect of gypenosides (GP) on the neurons of hippocampus, cerebral cortex, corpus striatum, and dentate gyrus in cerebral ischemia-reperfusion injury of rats.

METHODS

Modified 4-vessel occlusion (4-VO) method was used to establish the model of acute global ischemia. The acridine orange (AO) staining method was used to observe the DNA and RNA contents of cerebral ischemia-reperfusion injury model in the areas.

RESULTS

The fluorescent intensity (reflecting DNA and RNA contents) of the DNA and RNA in the areas of cerebral ischemia-reperfusion injury was markedly abated compared with the normal control group. In the group of ig GP (100 mg/kg) it was enhanced compared with the model group and was the same as the normal control group.

CONCLUSION

The injury of the DNA and RNA in the areas of ischemia-reperfusion model was decreased by GP.

[Enantioselective pharmacokinetics of benproperine in healthy volunteers]

AIM

To investigate the enantioselective pharmacokinetic process of benproperine in healthy volunteers.

METHODS

An enantiospecific HPLC method was developed and used to determine the plasma concentrations of each enantiomer. Six healthy Chinese male volunteers received an oral dose of 60 mg (+/-)-benproperine. The ratios of the enantiomers in plasma samples were measured on a chiral AGP column. The plasma concentration of each enantiomer was then calculated using the ratios of enantiomers and total concentration of the two enantiomers previously measured.

RESULTS

The plasma levels of (-)-(S)-benproperine were always significantly higher than those of its antipode in six volunteers. The mean AUC0-t and Cmax values for (-)-(S)-benproperine were 2.18 and 2.12 times higher than those of (+)-(R)-benproperine. There was no significant difference between the T1/2 for both enantiomers, tested by paired t test (P > 0.05). Half an hour after administration of benproperine, the S/R ratio in plasma samples was as high as 3.8, and in 2 hours it drastically decreased to about 2.2, then kept on till 24 hours.

CONCLUSION

Benproperine showed significant enantioselective pharmacokinetics in the human after an oral dose of the racemate.

[Study on hydroxylated metabolites of benproperine in human urine]

AIM

To investigate the hydroxylation process of benproperine in humans.

METHODS

After an oral administration of 60 mg benproperine to ten healthy male volunteers, urine samples collected within 0-24 h were extracted by solid phase extraction and analyzed by liquid chromatography-ion trap mass spectrometry. A microbial transformation of benproperine combined with semi-preparative HPLC was used to get two reference substances of the hydroxylated metabolites, and their structures were then elucidated by NMR. Furthermore, the structures of conjugated metabolites were speculated based on their characteristics in MS fragmentation.

RESULTS

Five hydroxylated metabolites of benproperine and some of their conjugates with endogenous glucuronic acid or sulfuric acid were found in urine of volunteers after the dose. The structures of two metabolites were identified as 4"-hydroxybenproperine and 4"'-hydroxybenproperine by comparison of HPLC retention times and mass spectra with those of authentics obtained from the microbial transformation.

CONCLUSION

Hydroxylation of benproperine occurs preferentially at para-position of the alkoxyl group in the aromatic ring. The hydroxylated metabolites of benproperine in human urine mainly exist as their glucuronic acid or sulfuric acid conjugates.

[RGS and the regulation of G protein signal transduction]

Regulators of G-protein signaling (RGSs) are recently identified negative regulator of G-protein signaling, most of the RGSs act as GTPase activating proteins (GAPs). RGSs can selectively act on Gas and their effects are scrupulously regulated in vivo. It is believed that we can learn more about regulation of signal transduction from the development of research on RGSs.

[Preliminary study on apoptosis of BEL-7402 cells induced by Chinese herbs for warming yang and dispersing stasis]

OBJECTIVE

To investigate the antitumor mechanism of Chinese herbs for warming yang and dispersing stasis and observe the action of these herbs in inducing apoptosis of BEL-7402 cells.

METHOD

Apoptosis of BEL-7402 cells induced by the above-said herbs was detected through fast red tablet staining, flow cytometry and terminal uridine deoxynucleotidyl and labeling (TUNEL).

RESULT

After treating BEL-7402 cells with the herbs typical apoptosis characteristics could be seen under light microscope and TUNEL positive cells were detectable. The apoptotic rate was 13.9% (drug concentration 0.5%) and 21.6% (drug concentration 1%)

CONCLUSION

Chinese herbs for warming Yang and dispersing stasis could induce apoptosis of BEL-7402 cells and this effect depends on drug concentration. Inducing the apoptosis of tumor cells may be part of the mechanism displayed by Chinese herbs for warming Yang and dispersing stasis in treating hepatoma.

Expression pattern of (+)-delta-cadinene synthase genes and biosynthesis of sesquiterpene aldehydes in plants of Gossypium arboreum L

The cotton (+)-delta-cadinene synthase, a sesquiterpene cyclase, is encoded by a complex gene family which, based on homology, can be divided into two subfamilies: cad1-A and cad1-C. Southern blots revealed several members of the cad1-C subfamily, and a single member of the cad1-A subfamily, in the diploid Gossypium arboreum genome. One of the cad1-C genes, cad1-C3, was isolated from this species. According to reverse transcriptase-polymerase chain reaction, transcripts of both cad1-C and cad1-A genes appeared in roots from the second day post germination and in 1-d-old cotyledons, whereas the transcription levels were too low to be detected in the hypocotyls. Initially, sesquiterpene cyclase activities were found to be high in the seedlings, then dropped in aerial organs but increased in roots during development. Sesquiterpene aldehyde contents followed the same pattern. In fully developed plants, the transcripts of cad1-C were detected in stems, leaves and pericarps, as well as in the sepals and petals 3 d before anthesis, but not at the day of anthesis. In contrast, cad1-A transcripts were not detected in any of these aerial organs. The sesquiterpene aldehyde contents increased in petals but decreased in sepals after anthesis. Treatment of G. arboreum stems with a Verticillium dahliae elicitor-preparation activated cad1-A transcription, but a significant level of cad1-C transcripts was detected both before and after elicitation. In G. hirsutum cv. GL-5, a glandless cultivar, the cad1-C gene was activated by the same fungal elicitor, followed by the synthesis of the sesquiterpene cyclase, and accumulation of sesquiterpene aldehydes. The cad1 gene expression during development and in response to elicitation, as well as the spatial and temporal pattern of sesquiterpene biosynthesis, constitute a chemical defense machinery in cotton plants.

[Study on the relationship between nitric oxide and allergic rhinitis]

OBJECTIVE

To investigate the relationship between nitric oxide (NO) and allergic rhinitis (AR).

METHOD

NO in the serum of 50 patients with AR and 40 healty control were measured by nitrate reductase.

RESULT

The level of serum NO in AR group was higher than that in healthy control group (P < 0.001).

CONCLUSION

There is a relationship between the level of NO in serum and AR. The results suggest that the NO may play an important role in the pathogenesis of AR.

Expression pattern of genes encoding farnesyl diphosphate synthase and sesquiterpene cyclase in cotton suspension-cultured cells treated with fungal elicitors

Cotton plants accumulate sesquiterpene aldehydes in pigment glands. The two enzymes farnesyl diphosphate synthase (FPS) and (+)-delta-cadinene synthase (CAD), a sesquiterpene cyclase, are involved in the biosynthesis of these secondary metabolites. A full-length cDNA (garfps) encoding FPS was isolated from Gossypium arboreum and identified by in vitro enzymatic assay of the garfps protein heterologously expressed in Escherichia coli. Treatment of G. arboreum suspension-cultured cells with an elicitor preparation obtained from the phytopathogenic fungus Verticillium dahliae dramatically induced transcription of both FPS and CAD, paralleling the accumulation of the sesquiterpene aldehydes in these cells. For G. australe, a wild species from Australia, the V. dahliae elicitor preparation also caused an induction of FPS but only a low rate of induction of CAD, apparently because of a constitutive expression of the sesquiterpene cyclase gene in suspension-cultured cells. Two transcripts and proteins of FPS were detected in the elicited G. australe cells; the smaller FPS seemed to be de novo synthesized after elicitation. Furthermore, G. australe-cultured cells accumulated the cadinene, instead of sesquiterpene aldehydes, indicating that the biosynthetic pathway leading to sesquiterpene aldehydes was absent or blocked after FPP cyclization.

(3R)-Linalool synthase from Artemisia annua L.: cDNA isolation, characterization, and wound induction

Artemisia annua is an annual herb used in traditional Chinese medicine. A cDNA library was constructed from leaves of A. annua seedlings and target sequences were amplified by PCR using degenerate primers derived from a consensus sequence of angiosperm terpene synthases. Two clones, QH1 and QH5, with high sequence similarity to plant monoterpene synthases were ultimately obtained and expressed in Escherichia coli. These cDNAs encode peptides of 567 aa (65.7 kDa) and 583 aa (67.4 kDa), respectively, and display 88% identity with each other and 42% identity with Mentha spicata limonene synthase. The two recombinant enzymes yielded no detectable activity with isopentenyl diphosphate, dimethylallyl diphosphate, chrysanthemyl diphosphate, farnesyl diphosphate, (+)-copalyl diphosphate, or geranylgeranyl diphosphate, but were active with geranyl diphosphate in yielding (3R)-linalool as the sole product in the presence of divalent metal cation cofactors. QH1-linalool synthase displays a K(m) value of 64 microM for geranyl diphosphate, which is considerably higher than other known monoterpene synthases, and a K(m) value of 4.6 mM for Mg(+2). Transcripts of QH1 and QH5 could be detected by RT-PCR in the leaves and inflorescence of A. annua, but not in the stem stele or roots; transcripts of QH5 could also be detected in stem epidermis. Linalool could not be detected by GC-MS in the essential oil of A. annua, nor in acid or base hydrolysates of aqueous extracts of leaves. RT-PCR demonstrated a wound-inducible increase in QH1 and QH5 transcript abundance in both leaves and stems over a 3-day time course.

Interobserver variation in the histopathological scoring of Helicobacter pylori related gastritis

AIM

To test the reproducibility between two histopathologists of features of Helicobacter pylori gastritis, using the updated Sydney classification.

METHODS

290 dyspeptic Dutch patients with biopsy proven H pylori infection were enrolled in the study. Gastric antral mucosal biopsy specimens were analysed before and after H pylori eradication treatment. The biopsies were scored semi-quantitatively by two histopathologists, according to the updated Sydney classification system. Variables analysed included the density of H pylori infection, the degree of chronic inflammation, inflammatory activity, atrophy, intestinal metaplasia, and surface epithelial damage. Before grading biopsy specimens, both pathologists reached a consensus on the scoring of gastritis through interactive sessions using a multiheaded microscope. Subsequently all biopsy specimens were graded. Interobserver variability was also analysed using weighted kappa scores.

RESULTS

For interobserver agreement on scoring the various gastritis features a high degree of reproducibility was reached overall. Agreement on grading of atrophy was the lowest; however, moderate to good reproducibility was achieved, with weighted kappa values of 0.49 in the pretreatment biopsies and 0.52 in the post-treatment biopsies. Disagreement was most common in biopsy specimens with lesser degrees of atrophy. A high degree of agreement was obtained for intestinal metaplasia, with weighted kappa values of 0.72 in the pretreatment biopsies and 0.73 in the post-treatment biopsies. The best agreement was reached in the assessment of the density of H pylori both before and after H pylori eradication treatment, with excellent weighted kappa values of 0.76 and 0.95, respectively. The grade of reproducibility of inflammatory activity, superficial epithelial damage, and chronic inflammation was high, with weighted kappa values varying from 0.60 to 0.76 and 0.62 to 0.83 before and after eradication, respectively.

CONCLUSIONS

Reproducibility of grading H pylori related gastritis is high using the updated Sydney system. Despite the novel criteria for scoring atrophy, there was imperfect agreement on this feature between two independent histopathologists.