Extracellular cyclophilin A may be a potential target to protect against myocardial reperfusion injury

Myocardial reperfusion injury is increasingly recognized as an inflammatory process, characterized by neutrophil recruitment and subsequently excessive release of pro-inflammatory factors. Recently, the extracellular cyclophilin A (CypA) has been showed to play an important role in initiation and development of inflammation by chemo trafficking of leukocytes into inflamed tissues, eliciting massive release of pro-inflammatory cytokines, and inducing production of matrix metalloproteinases. Also, the agents targeting CypA have been demonstrated to promise anti-inflammatory effects in the different experimental models of inflammatory diseases including acute lung injury, rheumatoid arthritis, and atherosclerosis. Therefore, we hypothesize that the extracellular CypA may in some way implicated in the pathogenesis of reperfusion-induced inflammatory process, and the specific inhibitors of the extracellular CypA can provide a protection against the myocardial reperfusion injury.

Angiotensin-converting enzyme insertion/deletion polymorphism associated with acute respiratory distress syndrome among caucasians

Studies investigating the association between angiotensin-converting enzyme (ACE) insertion/deletion polymorphisms and the risk of acute respiratory distress syndrome (ARDS) report conflicting results. The objective of the present study was to summarize quantitatively the evidence for such a relationship. Two investigators independently searched the MEDLINE (January 1966 - October 2009) and EMBASE (January 1980 - October 2009) databases. This meta-analysis included six case-control studies, which included 514 ARDS cases and 2619 controls. The combined results based on all studies showed that patients with ARDS had a significantly higher frequency of the ACE deletion/deletion (DD) genotype (odds ratio [OR] 1.56; 95% confidence interval [CI] 1.22, 2.00) than controls. When stratifying for race, no significant differences in genotype distribution were found except that Caucasian patients with ARDS had a significantly higher frequency of the DD genotype (OR 1.65; 95% CI 1.27, 2.13) than controls. This meta-analysis suggests that ACE insertion/deletion polymorphisms may be associated with ARDS among Caucasians.

Elevated glutathione production by adding precursor amino acids coupled with ATP in high cell density cultivation of Candida utilis

AIMS

Three precursor amino acids and adenosine triphosphate (ATP) are necessary for fermentative production of glutathione. In this study, our aims were to develop a strategy to enhance glutathione production by adding three precursor amino acids coupled with ATP in high cell density (HCD) cultivation of Candida utilis.

METHODS AND RESULTS

A high-glutathione yeast strain, C. utilis WSH 02-08, was used in this study. Whole fermentative process for glutathione production was divided into two phases of cell growth and glutathione synthesis. Cells concentration was increased by HCD cultivation. Meanwhile, intracellular glutathione content was enhanced by the addition of three precursor amino acids. Concentrations of three precursor amino acids added at stationary phase were optimized by response surface methodology. Moreover, the addition of ATP 15 h after the addition of the three amino acids can further enhance glutathione production. Based on aforementioned phenomenon, a strategy of adding three precursor amino acids coupled with ATP was developed to enhance glutathione production.

CONCLUSION

Without the addition of three precursor amino acids and the ATP, a total glutathione of 1123 mg l(-1) was achieved after 60-h cultivation. In comparison, addition of three precursor amino acid counterparts resulted in a total glutathione of 1841 mg l(-1). Moreover, by adding amino acids combined with ATP, a total glutathione of 2043 mg l(-1) was achieved after 72-h cultivation, increased by 81.9% and 11%, respectively, as compared with the control and the one without ATP addition.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report on investigating changes of the intracellular three precursor amino acids and ATP, and gamma-glutamylcysteine synthase activity in HCD cultivation of C. utilis for glutathione production. A strategy of combining addition of three precursor amino acids with ATP was developed to enhance glutathione production in C. utilis.

The effects of head flexion on airway seal, quality of ventilation and orogastric tube placement using the ProSeal laryngeal mask airway

This prospective self-controlled study was designed to evaluate the influences of head flexion on airway seal, quality of ventilation, and orogastric tube placement through the ProSeal laryngeal mask airway (ProSeal LMA) in 80 anaesthetised, paralysed adult patients. After the ProSeal LMA was inserted and the cuff pressure was set at 5.9 kPa, ventilation quality, airway seal pressure, fibreoptic positions of the cuff and the drainage tube, orogastric tube placement and efficacy of intermittent positive pressure ventilation (IPPV) were assessed in two randomly selected positions: neutral and flexed position. When compared to the neutral head position, the head flexed significantly improved the airway seal pressure and the quality of ventilation of the ProSeal LMA (p < 0.05). Fibreoptic scores of the cuff position did not correlate with either the ability to obtain excellent or adequate ventilation through the ProSeal LMA or the ability to generate an airway seal pressure of >or= 2 kPa. Orogastric tube placement via the drainage tube was successful on the first attempt in all patients in the neutral position compared with seven failures following three attempts in the flexed position (p < 0.05). There were no significant differences between the two head positions in the volume of air required to obtain an intracuff pressure of 5.9 kPa, fibreoptic score of the drainage tube position, and expiratory tidal volume and peak inspiratory pressure during IPPV (p > 0.05). In conclusion, head flexion improves airway seal and ventilation quality of the ProSeal LMA. However, placement of an orogastric tube via the drainage tube is impaired in the flexed position compared to the neutral position. Fibreoptic scoring of the ProSeal cuff position is not an accurate test to assess the airway seal and ventilation function.

Cloning, mapping and mutation analysis of human geneGJB5 encoding gap junction protein beta-5

By homologous EST searching and nested PCR a new human geneGJB5 encoding gap junction protein beta-5 was identified.GJB5 was genetically mapped to human chromosome 1p33-p35 by FISH. RT-PCR revealed that it was expressed in skin, placenta and fetal skin. DNA sequencing ofGJB5 was carried out in 142 patients with sensorineural hearing impairment and probands of 36 families with genetic diseases, including erythrokeratodermia (5 families), Charcot-Marie-Tooth disease (13), ptosis (4), and retinitis pigmentosa and deafness (14). Two missense mutations (686A-->G, H229R; 25C-->T, L9F) were detected in two sensorineural hearing impairment families. A heterologous deletion of 18 bp within intron was found in 3 families with heredity hearing impairment, and in one of the 3 families, a missense mutation (R265P) was identified also. But the deletion and missense mutation seemed not segregating with hearing impairment in the family. No abnormal mRNA or mRNA expression was detected in deletion carriers by RT-PCR analysis in skin tissue. Mutation analysis in 199 unaffected individuals revealed that two of them were carriers with the same 18 bp deletion.

Different small-dose sufentanil blunting cardiovascular responses to laryngoscopy and intubation in children: a randomized, double-blind comparison

BACKGROUND

Sufentanil is a potent opioid analgesic frequently used in clinical anaesthesia. This prospective, randomized, double-blind study was designed to assess the efficacy of different small-dose sufentanil attenuating the cardiovascular intubation response in healthy children, aiming at determining the optimal dose of sufentanil for this purpose.

METHODS

A total of 165 children aged 3-9 yr were randomized to one of four groups to receive the following in a double-blind manner: normal saline (Group 1), sufentanil 0.1 microg kg(-1) (Group 2), sufentanil 0.2 microg kg(-1) (Group 3), and sufentanil 0.3 microg kg(-1) (Group 4). Anaesthesia was induced with propofol 2.5 mg kg(-1) and vecuronium 0.1 mg kg(-1). Non-invasive blood pressure (BP) and heart rate (HR) were recorded before induction of anaesthesia (baseline value), at immediately before intubation (post-induction values), at intubation, and at 1 min intervals for 5 min after intubation. The per cent changes of systolic blood pressure (SBP) and HR during the observation were calculated.

RESULTS

Except for Group 4, tracheal intubation caused significant increases in BP and HR in Groups 1, 2, and 3 compared with baseline values. BP and HR at intubation and their maximum values during the observation were significantly different among the four groups. The maximum per cent increases of SBP and HR during the observation were 20 and 28% of baseline values, respectively, in Group 2, 13 and 13% in Group 3, and 0 and 4% in Group 4 compared with 24 and 37% in Group 1. Except for the Group 3 vs Group 4 comparison, the incidences of SBP and HR per cent increases >30% of baseline values were also significantly different among the four groups.

CONCLUSIONS

In combination with propofol for induction of anaesthesia in children, the bolus administration of sufentanil can produce a dose-related attenuation of the cardiovascular intubation response and sufentanil 0.3 microg kg(-1) can completely abolish the cardiovascular intubation response.

Laser-micromachined Fabry-Perot optical fiber tip sensor for high-resolution temperature-independent measurement of refractive index

We propose and demonstrate a Fabry-Perot (F-P) optical fiber tip sensor for high-resolution refractive-index measurement fabricated by using 157-nm laser micromachining, for the first time to our knowledge. The sensor head consists of a short air F-P cavity near the tip of a single-mode fiber and the fiber tip. The external refractive index is determined according to the maximum fringe contrast of the interference fringes in the reflective spectrum of the sensor. Such a sensor can provide temperature-independent measurement of practically any refractive index larger than that of air and offers a refractive-index resolution of ~4 x 10(-5) in its linear operating range. The experimental data agree well with the theoretical results.

Development of EST-SSRs by an efficient FIASCO-based strategy: a case study in rare minnow (Gobiocyrpis rarus)

Type I markers are useful for comparative mapping and other genetic analyses, but relatively difficult to develop. In the present study a microsatellite (SSR)-enriched cDNA library was constructed for the first time using the fast isolation by AFLP of sequences containing repeats (FIASCO) method in a small fish, Chinese rare minnow (Gobiocypris rarus). A total of 97.4% of the expressed sequence tags (ESTs) contained targeted CA-repeats, in which 29 unique EST-SSRs were identified. Ten out of the 28 loci for which primer pairs were designed were polymorphic with alleles ranging from three to seven (mean 4.50). Some of these EST-SSRs can be amplified in other species. These results proved that cDNA-FIASCO is an efficient way to isolate novel EST-SSRs in a fish.

Enhancement of glutathione production by altering adenosine metabolism of Escherichia coli in a coupled ATP regeneration system with Saccharomyces cerevisiae

AIMS

Adenosine triphosphate (ATP) during the enzymatic production of glutathione is necessary. In this study, our aims were to investigate the reason for low glutathione production in Escherichia coli coupled with an ATP regeneration system and to develop a new strategy to improve the system.

METHODS AND RESULTS

Glutathione can be synthesized by enzymatic methods in the presence of ATP and three precursor amino acids (L-glutamic acid, L-cysteine and glycine). In this study, glutathione was produced from E. coli JM109 (pBV03) coupled with an ATP regeneration system, by using glycolytic pathway of Saccharomyces cerevisiae WSH2 as ATP regenerator from adenosine and glucose. In the coupled system, adenosine used for ATP regeneration by S. cerevisiae WSH2 was transformed into hypoxanthine irreversibly by E. coli JM109 (pBV03). As a consequence, S. cerevisiae WSH2 could not obtain enough adenosine for ATP regeneration in the glycolytic pathway in spite of consuming 400 mmol l(-1) glucose within 1 h. By adding adenosine deaminase inhibitor to block the metabolism from adenosine to hypoxanthine, glutathione production (8.92 mmol l(-1)) enhanced 2.74-fold in the coupled system.

CONCLUSIONS

This unusual phenomenon that adenosine was transformed into hypoxanthine irreversibly by E. coli JM109 (pBV03) revealed that less glutathione production in the coupled ATP regeneration system was because of the poor efficiency of ATP generation.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results presented here provide a strategy to improve the efficiency of the coupled ATP regeneration system for enhancing glutathione production. The application potential can be microbial processes where ATP is needed.

Miniature in-line photonic crystal fiber etalon fabricated by 157 nm laser micromachining

A miniature in-line fiber-optic Fabry-Perot etalon is fabricated on a photonic crystal fiber (PCF) by using 157 nm laser micromachining for the first time to our knowledge. Experimental results show that such a PCF-based etalon has an excellent fringe visibility of up to approximately 26 dB due to the mirror-finish quality of the two cavity surfaces inside the PCF. This etalon can be used as an ideal sensor for precise strain measurement under high temperature of up to 800 degrees C. It can also offer some other outstanding advantages, such as fast and easy fabrication, high reproducibility, capacity of mass production, low cost, low temperature-strain cross-sensitivity, and high signal-to-noise ratio.

Different small-dose remifentanil blunting the cardiovascular response to laryngoscopy and intubation in children: a randomized double-blind comparison

BACKGROUND

The available data provide inconsistent results on the efficacy of small-dose remifentanil attenuating the cardiovascular response to intubation in children. Therefore, this randomized double-blind study was designed to assess the ability of different small doses of remifentanil on the cardiovascular intubation response in children, with the aim of determining the optimal dose of remifentanil for this purpose.

METHODS

One hundred and twenty-four children aged 3-9 yr were randomized to one of four groups to receive the following in a double-blind manner: normal saline (Group 1), remifentanil 0.75 microg kg(-1) (Group 2), remifentanil 1 microg kg(-1) (Group 3) and remifentanil 1.25 microg kg(-1) (Group 4). Non-invasive blood pressure and heart rate were recorded before anaesthesia induction (baseline value), immediately before intubation (postinduction values), at intubation and at 1 min intervals for 5 min after intubation.

RESULTS

Tracheal intubation caused significant increases in systolic blood pressure and heart rate in Groups 1-3 compared with the baseline values. The maximum percent increases of systolic blood pressure and heart rate were 10% and 26% of the baseline values, respectively, in Group 2; 5% and 14% in Group 3; and 1% and 8% in Group 4 compared with 27% and 37% in Group 1. Except for the Group 3 vs. Group 4 comparison, there were significant differences among the four groups in the maximum percent increases of systolic blood pressure and heart rate.

CONCLUSIONS

When used as part of anaesthesia induction with propofol and vecuronium in children, bolus administration of remifentanil resulted in a dose-related attenuation of the cardiovascular intubation response.

The circulatory responses to tracheal intubation in children: a comparison of the oral and nasal routes

The circulatory responses to laryngoscopic tracheal intubation in 62 healthy children undergoing surgery requiring tracheal intubation were studied. They were randomly assigned to receive either the oral or nasal route for intubation. Baseline non-invasive blood pressure and heart rate were recorded following induction of anaesthesia, at intubation and then every minute for 5 min. The percentage changes of systolic blood pressure and heart rate during the measurement period were calculated. The results demonstrated that intubation time was significantly longer in the nasal group. Both oral and nasal intubation caused significant increases in blood pressure and heart rate compared to baseline and postinduction values. However, there were no significant differences found between the two groups in relation to blood pressure and heart rate. The two groups were similar with respect to the percentage changes of systolic blood pressure and heart rate during the observation period. It is concluded that oral and nasal intubation using a direct laryngoscopy can result in a similar circulatory response in anaesthetised children.

Nonlinear torsional oscillations in rotating systems

Torsional oscillations, temporal variations in the differential rotation in rotating systems, are a well-established phenomenon in the fluid regions of convective stars and planets. We show for the first time that nonlinear torsional oscillations can be generated and maintained by convective instabilities in rotating systems.

The clinical observation of difficult laryngoscopy and difficult intubation in infants with cleft lip and palate

BACKGROUND

The aims of this study were to evaluate the incidence of difficult laryngoscopy in infants with cleft lip and palate and to observe its relationships with age, sites, and degrees of deformities.

METHODS

A total of 985 infants aged 1 month to 3 years, undergoing repair of cleft lip and palate were included in this study. The infants suffering from unilateral cleft lip, simple cleft palate, and combined bilateral cleft lip and palate were 465, 421, and 79 respectively. They were divided into three groups according to age; 1-6 months group, 6-12 months group and 1-3 years group.

RESULTS

The total incidence of difficult laryngoscopy was 4.77%. The incidence of difficult laryngoscopy was closely related to age, sites and degrees of deformities, and micrognathia. The incidence of difficult laryngoscopy was 7.06% in 1-6 months group, 2.90% in 6-12 months group, and 3.13% in 1-3 years group, and was greatest for infants with combined bilateral cleft lip and palate, less for those with left cleft lip and least for those with right cleft lip and simple cleft palate. The incidences of difficult laryngoscopy in infants with and without micrognathia were 50% and 3.83% respectively. The incidences of moderately difficult, difficult, and failed intubations were 1.02%, 0.91%, and 0.102% respectively.

CONCLUSIONS

Infants with cleft lip and palate, left cleft lip and alveolus, combined bilateral cleft lip and palate, micrognathia, and age <6 months were the important risk factors for difficult laryngoscopy. Difficult intubation occurred mainly in infants with laryngoscopic views of grade III and IV.

Immunohistochemical study of serum albumin in normal and cadmium-treated mouse testis organs by "in vivo cryotechnique"

The in vivo injection of cadmium (Cd) was reported to induce blood-testis barrier disruption, and assumed to be an experimental model to examine junctional structures in seminiferous tubules. The purpose of this study is to investigate time-dependent changes of albumin permeability in the normal or Cd-treated mouse testis by our "in vivo cryotechnique" with immunohistochemistry, reflecting tight junctional (TJ) barriers of Sertoli cells. The albumin in the seminiferous tubules was firstly immobilized by the cryotechnique, in which normal blood circulation was always kept. The cryofixed testicular tissues were then processed for freeze-substitution, and embedded in the paraffin wax. Serial sections were immunostained by anti-mouse albumin antibody with peroxidase immunostaining, and also stained with hematoxylin-eosine (HE) for morphological observation. In normal seminiferous tubules, the immunoreaction products were localized around peritubular myoid cells and between Leydig cells, as well as in blood vessels. They were also localized as arch-like patterns around some spermatogonia in basal compartments of seminiferous tubules. Twenty-four and 48 hrs after Cd-treatment, some enlarged spaces and vesicular formations in the seminiferous epithelium were observed on the HE-stained sections. The albumin immunolocalization was detected not only in the basal compartments, but also in the adluminal compartments between Sertoli cells and germ cells. Thus, the structural disruptions of inter-Sertoli TJ barriers could be clearly demonstrated by the "in vivo cryotechnique".

Study on the changes in microvessel density in hepatocellular carcinoma following transcatheter arterial chemoembolization

To study the changes in intratumoral microvessel density (MVD) in hepatocellular carcinoma (HCC) following transcatheter arterial chemoembolization (TACE), MVD in 42 HCC specimens histologically verified was studied by using immunohistochemical method. Of all the specimens, 20 were obtained from the patients treated with surgical resection alone, 22 from those with second stage surgical resection after TACE. The results showed that the MVD in HCC tissues was 53.4 +/- 21.9 in the TACE group and 27.6 +/- 9.2 in the single operating group, respectively, with the difference being significant between them (P < 0.001). It was suggested that TACE might contribute to angiogenesis of HCC, possibly due to anoxic stress and ischemia-reperfusion injury.

GapA and CrmA coexpression is essential for Mycoplasma gallisepticum cytadherence and virulence

It was previously demonstrated that avirulent Mycoplasma gallisepticum strain R(high) (passage 164) is lacking three proteins that are expressed in its virulent progenitor, strain R(low) (passage 15). These proteins were identified as the cytadhesin molecule GapA, the putative cytadhesin-related molecule CrmA, and a component of a high-affinity transporter system, HatA. Complementation of R(high) with wild-type gapA restored expression in the transformant (GT5) but did not restore the cytadherence phenotype and maintained avirulence in chickens. These results suggested that CrmA might play an essential role in the M. gallisepticum cytadherence process. CrmA is encoded by the second gene in the gapA operon and shares significant sequence homology to the ORF6 gene of Mycoplasma pneumoniae, which has been shown to play an accessory role in the cytadherence process. Complementation of R(high) with wild-type crmA resulted in the transformant (SDCA) that lacked the cytadherence and virulence phenotype comparable to that found in R(high) and GT5. In contrast, complementation of R(high) with the entire wild-type gapA operon resulted in the transformant (GCA1) that restored cytadherence to the level found in wild-type R(low). In vivo pathogenesis trials revealed that GCA1 had regained virulence, causing airsacculitis in chickens. These results demonstrate that both GapA and CrmA are required for M. gallisepticum cytadherence and pathogenesis.

A modified live Mycoplasma gallisepticum vaccine to protect chickens from respiratory disease

The aim of this study was to assess the efficacy of a modified live Mycoplasma gallisepticum vaccine (GT5) for the protection of chickens against infection and respiratory disease. GT5 was constructed by the reconstitution of the avirulent high passage R (R(high)) strain with the gene encoding the major cytadhesin GapA. GT5 expressed GapA on its surface yet retained the phenotypic characteristics of the parental R(high) strain. Birds vaccinated with GT5 were protected upon challenge with the virulent low passage R (R(low)) strain as evidenced by a complete absence of tracheal lesions 2 and 4 weeks post-challenge, in contrast to sham immunized/challenged control birds. Modest amounts of IgG, and little, if any secretory IgA or IgM anti-M. gallisepticum were found in tracheal washings following vaccination. However, copious amounts of specific IgA were found following challenge, especially in sham immunized birds. This suggests that the tracheal IgG elicited by GT5 vaccination may have been responsible for blocking the initial colonization of R(low), thereby resulting in protection.

[The effects of thrombopoietin and interleukin-11 on bone marrow megakaryocytic progenitors in patients with chronic idiopathic thrombocytopenic purpura in vitro]

OBJECTIVE

To observe the effects of recombinant human thrombopoietin (rhTPO) and rhTPO in combination with recombinant human interleukin-11(rhIL-11) on the megakaryocyte (MK) colony growth and maturation in patients with chronic idiopathic thrombocytopenic purpura (CITP) in vitro.

METHODS

Bone marrow (BM) mononuclear cells of 21 patients with CITP were cultured in plasma clot culture systems, to which were added rhTPO alone or rhTPO plus rhIL-11 over a range of concentrations. After 14 days, the MK colonies were stained by GP III a Mc Ab(SZ-21) and ABC-Kit and counted. The diameters and areas of the positive cells of GP III a were measured by BM-cell analysis system of MCDS-2010.

RESULTS

The diameters and areas of MK in CITP group were significantly lower than that in control group, P < 0.05. The addition of rhTPO to culture systems increased CFU-MK, total colonies and diameters and areas of MK in CITP patients. And this promoting effect was not dose-dependent. The optimal concentration of rhTPO was 10 ng/ml; in the group where 10 ng/ml rhTPO was used in combination with 20 ng/ml rhIL-11, the counts of CFU-MK, total colonies and the measurements of areas and diameters of MK increased significantly, compared with those in the group where rhTPO was used alone.

CONCLUSION

There are maturation dysfunctions of MK progenitors in patients with CITP. rhTPO alone or in combination with rhIL-11 can promote the proliferation and maturation of MK progenitors in patients with CITP and, moreover, the combination of the two cytokines has more significant promoting effects, compared to rhTPO alone.

The tetrahymena ribozyme cleaves a 5'-methylene phosphonate monoester approximately 10(2)-fold faster than a normal phosphate diester: implications for enzyme catalysis of phosphoryl transfer reactions

Single-atom substrate modifications have revealed an intricate network of transition state interactions in the Tetrahymena ribozyme reaction. So far, these studies have targeted virtually every oxygen atom near the reaction center, except one, the 5'-bridging oxygen atom of the scissile phosphate. To address whether interactions with this atom play any role in catalysis, we used a new type of DNA substrate in which the 5'-oxygen is replaced with a methylene (-CH2-) unit. Under (kcat/Km)S conditions, the methylene phosphonate monoester substrate dCCCUCUT(mp)TA4 (where mp indicates the position of the phosphonate linkage) unexpectedly reacts approximately 10(3)-fold faster than the analogous control substrates lacking the -CH2- modification. Experiments with DNA-RNA chimeric substrates reveal that the -CH2- modification enhances docking of the substrates into the catalytic core of the ribozyme by approximately 10-fold and stimulates the chemical cleavage by approximately 10(2)-fold. The docking effect apparently arises from the ability of the -CH2- unit to suppress inherently deleterious effects caused by the thymidine residue that immediately follows the cleavage site. To analyze the -O- to -CH2- modification in the absence of this thymidine residue, we prepared oligonucleotide substrates containing methyl phosphate or ethyl phosphonate at the reaction center, thereby eliminating the 3'-terminal TA4 nucleotidyl group. In this context, the -O- to -CH2-modification has no effect on docking but retains the approximately 10(2)-fold effect on the chemical step. To investigate further the stimulatory influence on the chemical step, we measured the "intrinsic" effect of the -O- to -CH2- modification in nonenzymatic reactions with nucleophiles. We found that in solution, the -CH2- modification stimulates chemical reactivity of the phosphorus center by <5-fold, substantially lower in magnitude than the stimulatory effect in the catalytic core of the ribozyme. The greater stimulatory effect of the -CH2- modification in the active site compared to in solution may arise from fortuitous changes in molecular geometry that allow the ribozyme to accommodate the phosphonate transition state better than the natural phosphodiester transition state. As the -CH2- unit lacks lone pair electrons, its effectiveness in the ribozyme reaction suggests that the 5'-oxygen of the scissile phosphate plays no role in catalysis via hydrogen bonding or metal ion coordination. Finally, we show by analysis of physical organic data that such interactions in general provide little catalytic advantage to RNA and protein phosphoryl transferases because the 5'-oxygen undergoes only a small buildup of negative charge during the reaction. In addition to its mechanistic significance for the Tetrahymena ribozyme reaction and phosphoryl transfer reactions in general, this work suggests that phosphonate monoesters may provide a novel molecular tool for determining whether the chemical step limits the rate of an enzymatic reaction. As methylene phosphonate monoesters react modestly faster than phosphate diesters in model reactions, a similarly modest stimulatory effect on an enzymatic reaction upon -CH2- substitution would suggest rate-limiting chemistry.

[The relativity study of thrombopoietin and chronic idiopathic thrombocytopenic purpura]

OBJECTIVE

To explore the relationship between thrombopoietin (Tpo) levels and reticulated platelet (RP), blood platelet count (BPC), maturity of megakaryocytes in patients with chronic idiopathic thrombocytopenic purpura (CITP), and the prediction evaluation according to Tpo levels.

METHODS

Serum level of Tpo was measured by a sandwich-ELISA procedure, RP by flow cytometry after stained with thizole orange (TO), and maturity of megakaryocytes by laser scanning confocal microscopy (LSCM).

RESULTS

The serum level of Tpo was (204.05 +/- 65.70) ng/L in 23 normal controls and (345.46 +/- 222.23) ng/L in 33 patients with CITP, being no significant difference between the two groups (P > 0.05). Compared with controls, serum Tpo levels in 22 aplastic anemia(AA) patients [(1427.62 +/- 468.84) ng/L] and 10 acute myelogenous leukemia (AML) patients [(596.09 +/- 462.95) ng/L] were increased significantly (P < 0.05). The RPC was significantly lower in AA and AML patients (P < 0.05). The RP% was increased significantly in CITP and AML patients (P < 0.05). The Tpo level was higher in CITP patients with no response to glucocorticoid therapy than in those with response (P < 0.05).

CONCLUSION

Serum level of Tpo was not increased in patients with CITP. The RP%, RPC and Tpo levels could reflect thrombocytopoiesis and differentiate the causes of thrombocytopenia. The serum level of Tpo could be useful in prediction of the response to therapy in CITP patients.