Specific detection of Bradyrhizobium and Rhizobium strains colonizing rice (Oryza sativa) roots by 16S-23S ribosomal DNA intergenic spacer-targeted PCR

In addition to forming symbiotic nodules on legumes, rhizobial strains are members of soil or rhizosphere communities or occur as endophytes, e.g., in rice. Two rhizobial strains which have been isolated from root nodules of the aquatic legumes Aeschynomene fluminensis (IRBG271) and Sesbania aculeata (IRBG74) were previously found to promote rice growth. In addition to analyzing their phylogenetic positions, we assessed the suitability of the 16S-23S ribosomal DNA (rDNA) intergenic spacer (IGS) sequences for the differentiation of closely related rhizobial taxa and for the development of PCR protocols allowing the specific detection of strains in the environment. 16S rDNA sequence analysis (sequence identity, 99%) and phylogenetic analysis of IGS sequences showed that strain IRBG271 was related to but distinct from Bradyrhizobium elkanii. Rhizobium sp. (Sesbania) strain IRBG74 was located in the Rhizobium-Agrobacterium cluster as a novel lineage according to phylogenetic 16S rDNA analysis (96.8 to 98.9% sequence identity with Agrobacterium tumefaciens; emended name, Rhizobium radiobacter). Strain IRBG74 harbored four copies of rRNA operons whose IGS sequences varied only slightly (2 to 9 nucleotides). The IGS sequence analyses allowed intraspecies differentiation, especially in the genus Bradyrhizobium, as illustrated here for strains of Bradyrhizobium japonicum, B. elkanii, Bradyrhizobium liaoningense, and Bradyrhizobium sp. (Chamaecytisus) strain BTA-1. It also clearly differentiated fast-growing rhizobial species and strains, albeit with lower statistical significance. Moreover, the high sequence variability allowed the development of highly specific IGS-targeted nested-PCR assays. Strains IRBG74 and IRBG271 were specifically detected in complex DNA mixtures of numerous related bacteria and in the DNA of roots of gnotobiotically cultured or even of soil-grown rice plants after inoculation. Thus, IGS sequence analysis is an attractive technique for both microbial ecology and systematics.

Synthesis and evaluation of novel aldose reductase inhibitors: Effects on lens protein kinase Cgamma

PURPOSE

To synthesize novel aldose reductase inhibitors (ARI) that will normalize losses in protein kinase Cgamma (PKCgamma) observed during diabetes and galactosemia.

METHODS

ARI were synthesized as tricyclic pyrones 1-6 (HAR-1 through HAR-6) from 3-methyl-1H,7H-5a,6,8,9-tetrahydro-1-oxopyrano[4,3-b][1]benzopyran and (5aS,7S)-7-isopropenyl-3-methyl-1H,7H-5a,6,8,9-tetrahydro-1-oxopyrano[4,3-b][1]benzopyran and were tested by inhibition of aldose reductase enzyme activity in vitro and by inhibition of polyol formation in lens epithelial cells in culture. Identified compounds were further tested in galactosemic rat lens in vivo for (a) normalized PKCgamma levels by Western blot, (b) reduction of phosphorylation of the gap junction protein Cx46 by analyses of co-immunoprecipitated proteins, and (c) by normalization of gap junction activity as measured by dye transfer.

RESULTS

HAR-1 (1H,7H-5a,6,8,9-tetrahydro-1-oxopyrano[4,3-b][1]benzopyran-3-acetic acid) was identified as an ARI with IC50 for aldose reductase inhibition at 2 nM. Polyol accumulation in lens epithelial cells was reduced by 80% at 10 microM. Rats fed 40% galactose for 9 days had an 80% reduction in PKCgamma levels which were normalized by HAR-1 at 100 mg/kg/day, fed orally. Phosphorylation of Cx46 was increased by 50% and this was normalized in HAR-1 treated rats (6 day treatment). Gap junction activity of galactosemic rats was reduced by 55% and this was normalized by HAR-1 in six day-treated rats.

CONCLUSIONS

HAR-1 is a novel ARI which normalized losses of PKCgamma, changes in Cx46 phosphorylation, and gap junction activity.

Downregulation of free ubiquitin: a novel mechanism of p53 stabilization and neuronal cell death

Neuronal death through activation of the p53 stress response pathway has been implicated in the pathogenesis of neurodegenerative disorders. The mechanisms regulating p53 accumulation and function in neurons are poorly understood. Recent evidence has demonstrated that Mdm2 is a major inhibitor of p53 that binds to and targets p53 for ubiquitin-mediated degradation. Here we demonstrate increased expression and co-localization of p53 and Mdm2 in the nuclei of degenerating neurons following treatment with either the excitotoxin, kainic acid, or the topoisomerase I inhibitor, camptothecin. Co-immunoprecipitation studies showed that p53-Mdm2 complexes were present in neuronal lysates. Dual immunofluorescence microscopy demonstrated that these complexes accumulated in neurons with a striking decrease in free ubiquitin levels. Exogenous ubiquitin restored p53 degradation to extracts from injured neurons confirming that Mdm2 function was intact. Finally, antisense-mediated downregulation of ubiquitin in cultured hippocampal neurons resulted in p53 and Mdm2 accumulation as well as apoptotic death. These results point to a novel mechanism to stabilize p53 and promote neuronal cell death in the central nervous system.

Increased expression of Fas (CD95/APO-1) in adult rat brain after kainate-induced seizures

Fas (CD95/APO-1), a transmembrane glycoprotein and receptor for the Fas ligand, plays an important role in apoptosis. The present study examined whether excitotoxic cell death induces Fas expression in the adult rat brain. Although relatively light immunostaining was observed in control brain sections, significantly increased Fas immunoreactivity was seen from 4 h to 5 days after the onset of kainic acid-induced seizures. Increased expression of both Fas mRNA and protein were also evident by reverse transcription polymerase chain reaction and Western blotting, respectively. Fas induction was correlated with neuronal apoptosis as demonstrated by colocalization of Fas and terminal dT-mediated dUTP nick end-labeling (TUNEL). Cells with increased Fas-expression were also immunoreactive for tumor suppressor p53 and neuronal specific nuclear protein (NeuN). These results suggest that Fas receptor may contribute to excitotoxic neuronal death in cooperation with p53, and further implicates the Fas pathway in the pathophysiology of neurodegenerative diseases.

Novel endophytes of rice form a taxonomically distinct subgroup of Serratia marcescens

Six endophytic strains isolated from surface-sterilized rice roots and stems of different rice varieties grown in the Philippines were characterized. They were analyzed by physiological and biochemical tests, SDS-PAGE of whole-cell protein patterns, DNA-DNA hybridization and 16S rDNA sequencing. SDS-PAGE of whole-cell patterns showed that the six isolates fell into two subgroups which were similar but not identical in protein patterns to S. marcescens. The phylogenetic analysis of 16S rDNA sequences of two representative strains IRBG 500 and IRBG 501 indicated that they were closely related to S. marcescens (more than 99% identity). Physiological and biochemical tests corroborated that the isolates were highly related to each other and to S. marcescens. In cluster analysis, all six isolates were clustered together at 93% similarity level and grouped closely with Serratia marcescens at 86% similarity level. DNA-DNA hybridization studies revealed that the isolates shared high similarity levels with S. marcescens (> or =86% DNA-DNA binding), indicating they belong to the same species. However, the isolates differed in several biochemical characteristics from the type strain. They produce urease and utilize urea and L(+) sorbose as a substrate, which is different from all known Serratia reference strains. These results suggest that the six endophytic isolates represent a novel, non-pigmented subgroup of S. marcescens.

Branched nanowire based guanine rich oligonucleotides

Self-assembly and aggregation of guanine rich sequences can provide useful insights into DNA nanotechnology and telomeric structure and function. In this paper, we designed a guanine rich sequence d(GGCGTTTTGCGG). We found that it can form stable structure in appropriate condition and it exhibits an anomalous CD spectra. This structures can be imaged in ambient environment with a Nanoscope III AFM (Digital Instruments). We found it forms branch structure and long multistrand DNA nanowire after incubation at 37 degrees C for 6-12 hours in 25 mM TE (pH=8.0) + 5 mM Mg2+ + 50 mM K+. The ability to self-assemble into branches and long wires not only clearly demonstrate its potential as scaffold structures for nanotechnology, but also give aids to understand telomeric structure further. We have proposed a model to explain how these structures formed.

[Glutamate induced modulation of free Ca2+ in isolated inner hair cells of the guinea pig cochlea]

OBJECTIVE

To investigate the modulation effect of glutamate (Glu) on intracellular free Ca2+ concentration([Ca2+]i) of inner hair cell (IHC).

METHODS

Using the laser scanning confocal microscope (LSCM), the exogenous Glu-induced changes in [Ca2+]i of isolated 10 IHCs and 10 OHCs of guinea pig cochlea were observed with fluo-3, a fluorescent probe for [Ca2+]i.

RESULTS

The IHCs were identified by their unique flask shape with a distinct neck and spherical base and a large spherical nucleus. In most cases, normal cell shapes could be maintained about two hours after isolation. The images of [Ca2+]i from LSCM were similar to those from inverted microscopy. Fluorescence of Fluo-3 distributed in the isolated IHCs with brighter staining in the nucleus. In the presence of low concentration of Glu (3.85 mumol/L), there was an increase of [Ca2+]i in IHCs, whereas no change in OHCs was found. Of the 10 IHCs, increases of [Ca2+]i were observed in 9 and no change in 1. Of the 10 OHCs, 7 showed no [Ca2+]i change and only 3 showed minor reduction of [Ca2+]i. An increase of the Glu concentration (21.88 mumol/L) induced a corresponding increase of [Ca2+]i in IHCs, but eventually resulted in a gradual decrease of [Ca2+]i with a distortion of the normal shape, which indicated that the IHCs were degenerated and swelling.

CONCLUSION

These results suggested that exogenous Glu is capable of modulating [Ca2+]i of IHC and may be act on autoreceptor in a positive feedback manner. Excessive Glu induced the accumulation of IHC [Ca2+]i which finally resulted in the degeneration and edema of IHC and the reduction of IHC [Ca2+]i.

Modulation of BmKAS-1 and BmK1-3-2 to sodium channel in rat dorsal root ganglion neurons

OBJECTIVE

To investigate what effects BmKAS-1 (a polypeptide purified from the Chinese scorpion Buthus martensi Karsch [BmK] and named as BmK activator of skeletal-muscle ryanodine receptor) and its upstream mixture BmK1-3-2 have on Na+ channels in dorsal root ganglion (DRG) small diameter neurons.

METHODS

The whole-cell patch-clamp technique was used to investigate the effects of BmKAS-1 and BmK1-3-2 on Na+ current in rat small diameter DRG neurons.

RESULTS

About 50% peak Na+ current was suppressed by 10 micrograms/ml of BmK1-3-2. 1.62 micrograms/ml of BmKAS-1 also blocked 50% peak Na+ current, and there was an obvious dose-dependent relationship.

CONCLUSION

Both BmK1-3-2 and BmKAS-1 have a blocking effect on Na+ channels, and this may one of the mechanisms for the analgetic effect of BmK1-3-2 and BmKAS-1.

[Effect of aldosterone on the secretion of endothelin by ventricular fibroblasts]

Using cell culture, radioimmunoassay for endothelin and RT-PCR, the effect of aldosterone on the endothelin secretion of ventricular fibroblasts was studied. The results showed that aldosterone (1 x 10(-7) mol/L) promoted the expression of ppET-1 mRNA, which began to increase in 2 hours and attained the highest level in 4 hours, thereafter decreased; aldosterone increased the endothelin level in ventricular fibroblasts and fibroblast conditioned growth medium (FCGM) as well, which was blocked by spironolactone (1 x 10(-6) mol/L), an aldosterone receptor antagonist. The results suggest that aldosterone can increase endothelin secretion by ventricular fibroblasts, which can be inhibited by its receptor antagonist spironolactone.

[The effect of aldosterone of promotion on proliferation of ventricular fibroblasts]

AIM

To study the effect of promoting aldosterone on proliferation of ventricular fibroblasts.

METHODS

Assay of [3H]-TdR incorporation rate and RT-PCR were used.

RESULTS

Aldosterone could promote [3H]-TdR incorporation of ventricular fibroblasts, the effective dose of aldosterone was among (1 x 10(-9)-1 x 10(-6))mol/L, and had dose-dependent manner, the c-fos gene was expressed after stimulated by aldosterone for 15 min, and studied the highest in 1 h, then reduced later. Spironolactone, aldosterone receptor antagonist could block the effect of aldosterone.

CONCLUSION

Aldosterone promotes the proliferation of ventricular fibroblasts, mediated by aldosterone receptor.

Simulated shortening of proliferation-restricting telomeres during clonal proliferation and senescence of human cells

In the absence of telomerase or other mechanisms to maintain their length, telomeres in human cells shorten at each round of cell division. This has been suggested to ultimately cause cell cycle exit when a critical telomere length is reached, leading to replicative senescence of the cell. At present, it is not clear whether the division potential of human cells is limited by the overall shortening of telomeres at all chromosomes or the shortening of specific telomeres on certain particular chromosomes. By computer simulations, my previous work has suggested that if the telomere theory is correct, the shortening of only a few, most likely two, telomeres might be preferentially involved in restricting the division of human cells. In this work, the length dynamics of individual telomeres in simulated cell clones were examined over their life span. It is shown that if the shortening of only two telomeres is responsible for restricting the proliferation of a cell, these two specific telomeres will shorten at different rates and have different length distributions from those of the rest telomeres. The unique pattern of length dynamics associated with the proliferation-restricting telomeres (PRT) provides a possibility of experimentally identifying these particular telomeres in human cells.

[A preliminary study on the activation of superoxide dismutase by Tiopronin in patients with chronic hepatitis B]

OBJECTIVE

To observe the clearance effect of Tiopronin on oxygen free radicals in chronic hepatitis B patients.

METHODS

The ranthine oxidase assay was used to detect superoxide dismutase (SOD) in 80 chronic hepatitis B patients, the ALT, TBil, TP and AIG ratio of the patients were also tested. The 80 chronic hepatitis B patients were divided into two groups, the control group was treated with routine liver protective and jaundice regressing drugs while the treated group was additionally administered with Tiopromin besides the routine treatment.

RESULTS

In two groups of patients with similar ages and sexes, there showed no differences in levels of SOD, ALT, TBil, TP and ALB before treatment, as the SOD in treated group and control group were 106.57 (40.68 NU/ml and 105.18(44.59 NU/ml respectively, while the normal value for SOD in 16 normal persons was 165.9(23.36 NU/ml. After treatment, there were significant differences (P< 0.01) in SOD, ALT, TBil and ALB levels which showed SOD 187.93(35.24 NU/ml, ALT 38.41(22.22 U/L, TBil 23.15(12.46 micromol/L, ALB 43.28 (4.21 g/L in the treated group and SOD 157.96(47.29 NU/ml, ALT 68.52(34.19 U/L, TBil 30.38(21.80 micromol/L and ALB 40.36(5.19 g/L in the control group.

CONCLUSIONS

There showed a good therapeutic effect of Tiopronin on the clearance of oxygen free radicals in chronic hepatitis B patients and also it can improve the liver function.

Chemical hypoxia-ischemia induces apoptosis in cerebromicrovascular endothelial cells

Cerebral endothelial cell (CEC) death from ischemia may exacerbate brain injury by altering microvascular integrity, but little is known concerning the pattern of CEC death and disruption of tight junction between two CECs to ischemia. To address these questions, CECs were isolated from bovine, cultured, and placed in glucose-free medium containing sodium cyanide. Trypan blue staining shown that sodium cyanide resulted in a dose-dependent insult of CECs (10-80 mM). CEC injury increased progressively with the duration of 20 mM cyanide exposure, becoming significant (71%) after 12 h. The mode of cell death induced by cyanide is clearly apoptosis in CECs, as shown by Hoechst 33,342 staining and transmission electron microscope, i.e. cyanide induced condensation and margination of chromatin, nuclear fragmentation and shrinkage of cell body and condensed apoptotic bodies in CECs. Most importantly, we found that the tight junction between two CECs was disrupted 12 h after chemical-ischemia, i.e. when CECs underwent apoptosis, the tight junctional complexes became thinner and rough; the cleft of tight junction between two CECs became blurred and more wider, and membranes of tight junction were course and irregular; and the adherens junctions were damaged. These results indicate that chemical hypoxia-ischemia induces apoptotic cell death in CECs and alters the microvascular integrity by disrupting tight junction complexes, and suggest that CEC apoptotic death and disruption of tight junction may exacerbate ischemic insults to brain. Thus, prevention of CEC apoptotic death may contribute to improvements of ischemic insults.

Lateralized cortical perfusion in women with Alzheimer's disease

OBJECTIVE

To define the pathophysiologic substrate of gender differences in cognition and behavior in Alzheimer's disease (AD).

DESIGN

Hemispheric regional cerebral blood flow (rCBF) was studied in a consecutive series of dementia patients using single photon emission computed tomography (SPECT).

PARTICIPANTS

Subjects included 300 outpatients who were studied with SPECT as part of a diagnostic evaluation for degenerative dementia or memory disorder.

METHOD

Based on qualitative descriptions by a radiologist, subjects were classified as having unilateral left, unilateral right, bilateral, or no perfusion defects. Semiquantitative analysis of SPECT images was also performed using region of interest radionuclide counts normalized to the cerebellum.

RESULTS

Among 174 females and 126 males, unilateral left hemisphere defects were found more commonly in women than men (24% vs 10%; chi 2 = 9.4; P = .009). This observation was most significant for the 103 females and 62 males regarded as having probable AD (26% vs 8%; chi 2 = 9.3; P = .01). In a multiple regression model of clinical variables, shorter duration of disease and female gender were significant independent predictors of the unilateral left hemisphere pattern among those with probable AD. Age, family history, education, handedness, and severity of cognitive impairment were not significant contributors.

CONCLUSIONS

Women with AD exhibit greater heterogeneity in rCBF than men. Asymmetry in rCBF occurs more often in women. In some cases, this is related to relative preservation of right hemisphere function in women.

Identification of a novel ligand-receptor pair constitutively activated by ras oncogenes

The Ras signaling pathway is thought to control the expression of a subset of yet to be defined genes that are crucial for cell growth and differentiation. Here we have identified by differential display a novel oncogenic Ras target, mob-5, encoding a 23-kDa cytokine-like secreted protein. Mob-5 expression could be induced by oncogenic Ha-ras and Ki-ras, but not by normal ras activation. Inhibitors of both Ha-Ras and mitogen-activated protein kinase kinase completely abolished the mob-5 expression in ras transformed cells, with concomitant loss of the transformation phenotype. Using an alkaline phosphatase-tagged Mob-5 as ligand, a putative Mob-5 receptor was identified on the cell surface of oncogenic ras transformed cells. Thus, the Mob-5/Mob-5 receptor may represent a novel putative autocrine loop coordinately activated by ras oncogenes.

Atomic force microscopy analysis of intermediates in cobalt hexammine-induced DNA condensation

The packaging pathway of cobalt hexammine-induced DNA condensation on the surface of mica was examined by varying the concentration of Co(NH3)6(3+) in a dilute DNA solution and visualizing the condensates by atomic force microscopy (AFM). Images reveal that cobalt hexammine-induced DNA condensation on mica involves well-defined structures. At 30 microM Co(NH3)6(3+), prolate ellipsoid condensates composed of relatively shorter rods with linkages between them are formed. At 80 microM Co(NH3)6(3+), the condensed features include toroids with average diameter of approximately 240 nm as well as U-shaped and rod-like condensates with nodular appearances. The results imply that the condensates, whether toroids, U-shaped or rod-like structures have similar intermediate state which includes relatively shorter rod-like segments. The average size of the condensed toroids after incubated at room temperature for 5 h (approximately 240 nm) is much larger than that incubated for 0.5 h (approximately 100 nm). The results indicate that the condensation of DNA by Co(NH3)6(3+) is a kinetic-controlled process.

Determining the growing season of land vegetation on the basis of plant phenology and satellite data in Northern China

The objectives of this study are to explore the relationships between plant phenology and satellite-sensor-derived measures of greenness, and to advance a new procedure for determining the growing season of land vegetation at the regional scale. Three phenological stations were selected as sample sites to represent different climatic zones and vegetation types in northern China. The mixed data set consists of occurrence dates of all observed phenophases for 50-70 kinds of trees and shrubs from 1983 to 1988. Using these data, we calculated the cumulative frequency of phenophases in every 5-day period (pentad) throughout each year, and also drew the cumulative frequency distribution curve for all station-years, in order to reveal the typical seasonal characteristics of these plant communities. The growing season was set as the time interval between 5% and 95% of the phenological cumulative frequency. Average lengths of the growing season varied between 188 days in the northern, to 259 days in the southern part of the research region. The beginning and end dates of the surface growing season were then applied each year as time thresholds, to determine the corresponding 10-day peak greenness values from normalized difference vegetation index curves for 8-km2 pixels overlying the phenological stations. Our results show that, at the beginning of the growing season, the largest average greenness value occurs in the southern part, then in the northern, and finally the middle part of the research region. In contrast, at the end of the growing season, the largest average greenness value is measured in the northern part, next in the middle and lastly the southern part of the research region. In future studies, these derived NDVI thresholds can be applied to determine the growing season of similar plant communities at other sites, which lack surface phenological data.

p53 accumulation due to down-regulation of ubiquitin: relevance for neuronal apoptosis

The p53 tumor suppressor protein is a major regulator of cell growth arrest and apoptosis in response to DNA damage. Both p53 function and stability are tightly controlled by Mdm2, which binds to the p53 N-terminus and targets p53 for ubiquitin-mediated proteolysis. Previous studies suggest that adrenalectomy-induced neuronal apoptosis is p53-dependent. Here we demonstrate both nuclear accumulation and functional activation of p53 protein in apoptotic hippocampal neurons from adrenalectomized rats. Increased p53 expression occurred despite the accumulation of its negative regulator, Mdm2, and the formation of p53-Mdm2 complexes. The persistence of p53 expression was explained by a striking decrease in free ubiquitin in p53-positive neurons. The addition of exogenous ubiquitin to p53-Mdm2 complexes from apoptotic neurons restored p53 degradation. These findings demonstrate a novel mechanism of p53 stabilization mediated by decreased ubiquitin levels. Regulation of free ubiquitin may therefore be an effective way to modulate p53-dependent apoptosis in certain cell types.

[Effect of emodin on fibroblasts in lupus nephritis]

OBJECTIVE

To observe the effects of emodin on human fibroblasts in culture of kidney in patients with lupus nephritis (LN).

METHODS

Fibroblasts were isolated from culture of kidney of LN patients, and the effect of emodin on 3H-TdR incorporated rate of fibroblasts was observed. The apoptosis and c-myc gene expression were detected in the same time by flow cytometry.

RESULTS

Emodin could inhibit the proliferation of fibroblasts, and promote the programmed cell death through upregulate c-myc gene expression in human renal fibroblasts.

CONCLUSION

Emodin can inhibit proliferation and promote apoptosis of fibroblasts, which may be important in ameliorate interstitial fibrosis, thus improving prognosis of LN.

[p16, p53 and c-erbB-2 gene expression in bladder carcinoma]

OBJECTIVE

To investigate the expression of p16, p53 and c-erbB-2 proteins in bladder carcinoma and to analyze their correlation with tumor grade, clinic stage and metastasis.

METHODS

Immunohistochemical method was used to detect the p16, p53 and c-erbB-2 gene expressions in 75 cases of bladder carcinoma.

RESULTS

Positive rates of p16, p53 and c-erbB-2 in 75 cases of bladder cancer were 41.3%, 44.0% and 40.0%, respectively. p16 and c-erbB-2 gene expressions were related to the tumor grade and clinic stage (P < 0.05); p53 and c-erbB-2 gene expressions were related to the clinic stage and metastasis (P < 0.01). Oncogenes and/or antioncogenes altered expressions were found in 77.3% cases of bladder carcinoma, and oncogenes and/or antioncogenes with multiple altered expressions were found in 53.3% cases.

CONCLUSION

The analysis of multiple oncogene and/or antioncogene is more valuable than that of single oncogene and/or antioncogene. The altered expression of oncogene c-erbB-2 and antioncogenes p16 and p53 might play a promotive role in the tumorigenesis and development of bladder tumors.

Effects of local anesthetics on phospholipase D activity in differentiated human promyelocytic leukemic HL60 cells

Local anesthetics impair certain functions of neutrophils, and phospholipase D (PLD) is considered to play an important role in the regulation of these functions. To understand the mechanisms by which local anesthetics suppress the functions of neutrophils, we examined the effects of local anesthetics on PLD in neutrophil-like differentiated human promyelocytic leukemic HL60 cells. Tetracaine, a local anesthetic, inhibited formyl-methionyl-leucyl-phenylalanine (fMLP)- and 4beta-phorbol 12-myristate 13-acetate (PMA)-induced PLD activation, but potentiated fMLP-stimulated phospholipase C activity. All four local anesthetics tested suppressed PMA-induced PLD activation to different extents, and the order of their potency was tetracaine > bupivacaine > lidocaine > procaine. In a cell-free system, tetracaine suppressed guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS)-induced PLD activation as well as PMA-induced PLD activation. Western blot analysis revealed that tetracaine prevented the membrane translocation of PLD-activating factors, ADP-ribosylation factor, RhoA, and protein kinase Calpha. Tetracaine also inhibited the activity of recombinant hPLD1a in vitro. These results suggest that local anesthetics suppress PLD activation in differentiated HL60 cells by preventing the membrane translocation of PLD-activating factors, and/or by directly inhibiting the enzyme per se. Therefore, it could be assumed that local anesthetics would suppress the functions of neutrophils by inhibition of PLD activation.

Telomere shortening and the population size-dependency of life span of human cell culture: further implication for two proliferation-restricting telomeres

Cultures of normal human cell can only undergo a finite number of population doublings. The proliferative life span of a culture is affected by population size, i.e., the number of cells a culture maintains. A 1000-fold transient reduction in population size can reduce the life span by as many as eight population doublings. The limited proliferative potential of human cells has been speculated to be a result of telomere shortening that occurs during DNA synthesis at each round of cell division. In this paper, I use computer simulation to test the telomere theory of cell aging against the population size-dependency of life span of human cell culture. It is found that telomere shortening well explains the above phenomenon. In addition, the results suggest that the proliferative potential of human cells might be limited by the shortening of only a few, most likely two, specific telomeres, providing further support to the same conclusion put forward in my previous paper (Tan, 1999).

Local anesthetics inhibit muscarinic receptor-mediated activation of extracellular signal-regulated kinases in rat pheochromocytoma PC12 cells

BACKGROUND

Because protein phosphorylation is a key mechanism for controlling cellular functions and extracellular signal-regulated kinase (ERK) plays a role in cellular signal transduction, the authors wanted to determine whether local anesthetics interfere with biochemical signaling molecules.

METHODS

Protein tyrosine phosphorylation and ERK activation induced by carbachol, an agonist for muscarinic acetylcholine receptors, were examined in rat pheochromocytoma PC12 cells, a model for investigating signal transduction. Carbachol-induced tyrosine-phosphorylated proteins of 44 and 42 kd were determined by Western blot analysis and identified as activated ERK1 and ERK2 using anti-ERK antibody. The ERK activation was blocked by preincubation with atropine or an M3 muscarinic acetylcholine receptor antagonist 4-diphenyacetooxy-1, 1-dimethylpiperidinium, indicating that is was mediated by M3 muscarinic acetylcholine receptor activation. Then, in the presence of local anesthetic, the carbachol-induced tyrosine phosphorylation and ERK activation were evaluated. The effects of three Na+ current-modifying reagents on carbachol-induced ERK activation were also evaluated.

RESULTS

Procaine (10(-4) to 10(-3) M) inhibited carbachol-induced tyrosine phosphorylation and ERK activation in a concentration-dependent manner. Although tetracaine, lidocaine, and bupivacaine similarly suppressed carbachol-induced tyrosine phosphorylation and ERK activation, neither tetrodotoxin, veratridine, nor ouabain affected the carbachol-induced ERKs activation. Both ERKs were also activated by 4beta-phorbol 12-myristate 13-acetate, an activator of protein kinase C, and fluoroaluminate (AlF4-), respectively, but procaine did not affect ERK activation induced by these two substances. The inhibition of carbachol-induced ERK activation by procaine was not modified by a phosphatase inhibitor, calyculin A.

CONCLUSIONS

The current results indicate that local anesthetics inhibit the activity of the signal-transducing molecule(s) leading to M3 muscarinic acetylcholine receptor-mediated ERK activation in PC12 cells. Such action is unlikely to be a result of the drug's action on Na+ channels or on the electrochemical gradients of the neuronal cell membrane.

Treatment of epigastralgia by external application of huweigao at shenque point

140 cases of epigastralgia were divided into two groups at random. The 100 cases in the treatment group were treated with Huweigao externally applied at Shenque (Ren 8), and the 40 cases in the control group by oral administration of Weinaian capsule. After a one-month treatment, the total symptom-relieving rate and the gastroscopy-proved effective rate were 94.0% and 52.6% respectively in the treatment group, much superior to those in the control group.