Constitutive levels of cAMP-dependent protein kinase activity determine sensitivity of human multidrug-resistant leukaemic cell lines to growth inhibition and apoptosis by forskolin and tumour necrosis factor alpha

The cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA) signal pathway regulates cell proliferation, differentiation and cell death. It may also regulate the multidrug resistance (MDR) phenotype in leukaemic cells. These data showed that MDR1+ K/Dau600 cells exhibited a higher basal level of PKA activity than MDR- parental cells. The significance of this on tumour necrosis factor alpha (TNFalpha)-induced apoptosis and cytostasis was investigated further. In comparison with MDR1- parental cells, K/Dau600 cells had a higher expression of PKA regulatory subunit RIalpha and nuclear catalytic subunit PKAcalpha. They were also more susceptible to inhibition of proliferation and induction of apoptosis by TNFalpha and/or forskolin, but this could be attenuated by H89. An increase in cAMP was associated with the apoptosis in the K/Dau600 cell line. Forskolin inactivated NF-kappaB in K/Dau600 cells but not in K562 cl. 6 cells, whereas TNF activated NF-kappaB in K562 cl.6 cells but not in K/Dau600 cells. 8-Cl-cAMP exhibited similar inhibitory effects on the proliferation of all of the cell lines used via its metabolite 8-Cl-adenosine, which indicates that these effects were independent of residual PKA or cAMP. Therefore, the differential sensitivity to apoptosis and/or growth inhibition could be mediated via cAMP, partly through PKA via NF-kappaB and partly by PKA-independent pathways.

2.9 A crystal structure of ligand-free tryptophanyl-tRNA synthetase: domain movements fragment the adenine nucleotide binding site

The crystal structure of ligand-free tryptophanyl-tRNA synthetase (TrpRS) was solved at 2.9 A using a combination of molecular replacement and maximum-entropy map/phase improvement. The dimeric structure (R = 23.7, Rfree = 26.2) is asymmetric, unlike that of the TrpRS tryptophanyl-5'AMP complex (TAM; Doublié S, Bricogne G, Gilmore CJ, Carter CW Jr, 1995, Structure 3:17-31). In agreement with small-angle solution X-ray scattering experiments, unliganded TrpRS has a conformation in which both monomers open, leaving only the tryptophan-binding regions of their active sites intact. The amino terminal alphaA-helix, TIGN, and KMSKS signature sequences, and the distal helical domain rotate as a single rigid body away from the dinucleotide-binding fold domain, opening the AMP binding site, seen in the TAM complex, into two halves. Comparison of side-chain packing in ligand-free TrpRS and the TAM complex, using identification of nonpolar nuclei (Ilyin VA, 1994, Protein Eng 7:1189-1195), shows that significant repacking occurs between three relatively stable core regions, one of which acts as a bearing between the other two. These domain rearrangements provide a new structural paradigm that is consistent in detail with the "induced-fit" mechanism proposed for TyrRS by Fersht et al. (Fersht AR, Knill-Jones JW, Beduelle H, Winter G, 1988, Biochemistry 27:1581-1587). Coupling of ATP binding determinants associated with the two catalytic signature sequences to the helical domain containing the presumptive anticodon-binding site provides a mechanism to coordinate active-site chemistry with relocation of the major tRNA binding determinants.

Male sterility and enhanced radiation sensitivity in TLS(-/-) mice

TLS (also known as FUS) is an RNA-binding protein that contributes the N-terminal half of fusion oncoproteins implicated in the development of human liposarcomas and leukemias. Here we report that male mice homozygous for an induced mutation in TLS are sterile with a marked increase in the number of unpaired and mispaired chromosomal axes in pre-meiotic spermatocytes. Nuclear extracts from TLS(-/-) testes lack an activity capable of promoting pairing between homologous DNA sequences in vitro, and TLS(-/-) mice and embryonic fibroblasts exhibit increased sensitivity to ionizing irradiation. These results are consistent with a role for TLS in homologous DNA pairing and recombination.

[The influence of different root length on stress distribution in the bone around abutment root of telescopic overdenture]

OBJECTIVE

To investigate the influence of bone height around the roots on stress distribution in a mandible with two canines remained and covered with an telescopic overdenture.

METHODS

Three-dimensional finite element method.

RESULTS

As the height of the bone around the roots decreased, the stress increased. But the maximum stress in the bone in this study is lower than that in the bone around the canine under normal condition.

CONCLUSION

In the mandible, when the alveolar bone resorption reaches the apical 1/3 of canine (root length 4, 5 mm), if part of the tooth crown was removed, to make an acceptable crown/root ratio, so the canine can be used as the abutment of an overdenture.

Breakpoints of the t(11;18)(q21;q21) in mucosa-associated lymphoid tissue (MALT) lymphoma lie within or near the previously undescribed gene MALT1 in chromosome 18

Lymphomas arising in mucosa-associated lymphoid tissue (MALT) are indolent B-cell tumors that have a predilection for epithelial sites and often develop in a setting of chronic inflammation or autoimmunity. As many as 50% of low-grade MALT lymphomas contain an (11;18)(q21; q21) chromosomal translocation. Using fluorescence in situ hybridization, we have analyzed the position of recombination within chromosome 18 DNA in three examples of MALT lymphoma bearing this translocation. In all three cases, the breakpoint maps to DNA in BAC b357H2, covering about 150 kb of sequence. A previously undescribed, ubiquitously expressed gene, which we refer to as MALT1, was identified within this sequence and was found to be broken in one case for which we have definitively located the position of recombination between chromosomes 18 and 11. The sequence of this gene indicates the presence of two immunoglobulin-like C2 domains and a region of partial homology to caspases, suggesting a possible role for MALT1 in the regulation of apoptosis.

[Clinical observation of phenytoin in promoting fracture healing]

OBJECTIVE

To observe the promoting effect of phenytoin on fracture healing.

METHODS

Fourty cases with close fractures of tibia and fibula were included and divided into two groups randomly: the experimental group was administrated with phenytoin and Chinese traditional drug-Jiegudan orally, while the control group was given Jiegudan only. Longitudinal percussion pain, clinical healing time of fracture, growth of calus in X-ray film were detected to evaluate the clinical result.

RESULTS

All the fractures were healed in 3 months. But the experimental group was superior to the control group in all indexes.

CONCLUSION

Administration of phenytoin orally can markedly promote fracture healing.

Apolipoprotein CIII from guinea pig (Cavia porcellus) is shorter and less homologous than apolipoprotein CIII from other mammals

Apolipoprotein (apo) CIII plays an important role in metabolism of triglyceride-rich lipoproteins as a regulator of lipolysis and/or lipoprotein-receptor interaction. With the method of RT-PCR, the cDNA of guinea pig apo CIII was cloned and sequenced. The deduced amino acid sequence of 91 amino acids residues consists of a highly conserved signal peptide of 20 residues and a mature protein of 71 residues. Compared to mouse, rat, dog, bovine and human apo CIII, guinea pig apo CIII has a deletion of eight or nine amino acids at its C-terminus and it shows the lowest degree of homology to the presently known apo CIII sequences. Interestingly, the most conserved areas of guinea pig apo CIII are found in two regions, residues 16-33 and residues 50-69. Corresponding regions in human and dog apo CIII were previously predicted to form amphipathic helices, which are assumed to play important roles in the inhibition of lipoprotein lipase (LPL) and binding to lipid. Our present study could be helpful for the future elucidation of the structure-function relationships and evolution of apo CIII.

A study on the methods for early serological diagnosis of leprosy and their potential use

This is a serial study. In this series we have established 12 methods for the early serological diagnosis of leprosy, including the FLA-ABS test, ELISAs with artificial products (ND-O-, ND-P-, NT-O-, NT-P-BSA; PGL-I, whole M. leprae and M. smegmatis), monoclonal antibody specific binding assay (McAb/SBA), latex agglutination test (LAT), and MLPA. These methods were compared with each other on a large scale in leprosy patients and in the field. The results indicate that 1) Excellent results were obtained when ELISAs were conducted with skim milk or egg albumin as the blocking agent and by using blood from earlobes instead of from venipuncture. 2) According to the four "S" standard (sensitivity, specificity, simplicity and speed), among the 12 methods the ND-O-BSA-ELISA (ND-ELISA) is the best and the MLPA is more suitable for use in the field because it is simple and rapid. 3) In the ND-ELISA, the increase or decrease of the OD value has a positive correlation with the BI, and the order of positive rates was a) in various types of leprosy: LL > BL > BB > BT > TT; b) in household contacts (HC), random population (RP), normal controls in endemic areas (ENC) and normal controls in nonendemic areas (NNC): HC > RP > ENC > NNC. 4) In a population with subclinical M. leprae infection, the highest risk group was between the ages of 15 and 25 and had an increase or a persistence of high OD values prior to onset of disease. 5) OD values gradually decreased over time following treatment and these declines paralleled declines in the BI. 6) In cases cured with dapsone therapy, there was an increase or a persistence of high OD values in ND-ELISA prior to the onset of a leprosy relapse. In conclusion, we have compared and evaluated 12 immuno-assays and have shown that the ND-ELISA is the most practical one for use in investigating sero-immunological epidemiology, subclinical infection with M. leprae, early detection of disease, monitoring of antimicrobial therapy, and even for the prediction of leprosy relapse.

A double blind observation for therapeutic effects of the tong luo kai bi tablets on rheumatoid arthritis

The therapeutic effects of the Tong Luo Kai Bi Tablets [symbol: see text] in 120 patients with rheumatoid arthritis were observed in this clinical trial by the randomized double blind method. Both the observed group and the control group each had 60 patients. In the observed group treated with the Tong Luo Kai Bi Tablets, 1 case (1.7%) was cured clinically, 27 cases (45.0%) improved markedly, 26 cases (43.3%) improved, with a total effective rate of 90.0%. In the control group treated with Rheumatic Semen Strychni Tablets [symbol: see text], no case was cured, 16 cases (26.7%) improved markedly, 33 cases (55.0%) improved, with a total effective rate of 81.7%. Statistical data showed the Tong Luo Kai Bi Tablets had much better therapeutic effectiveness clinically than the Rheumatic Semen Strychni Tablets (P < 0.05).

[Clinical and experimental study on treatment of ankylosing spondylitis]

OBJECTIVE

To explore the effect and mechanism of Gubiyin (GBY) in treating ankylosing spondylitis (AS).

METHODS

The 70 patients of AS were randomly divided into two groups, 40 patients in the GBY group were treated with GBY and 30 patients treated with indomethacin for control. Animal experiments were also conducted.

RESULTS

Clinical observation showed that the markedly effective rate of the GBY group (57.5%) was higher than that of the control group (23.3%, P < 0.01), but the total effective rate of the two groups were similar. The effects of GBY in relieving symptoms of joints, improving function of joints, preventing degeneration of bone and improving laboratory parameters were better than those of indomethacin. In animal experiments, GBY showed its inhibition on granuloma formation, adjuvant arthritis in mice, and IL-1 production of abdominal macrophage and IL-2 production of spleen cell in rats.

CONCLUSION

GBY has effects of anti-inflammation, analgesic, immunoregulation, inflammation mediator inhibition and hemorrheology improvement.

[A rapid separation and quantitation of sodium cyclamate in food by ion-pair reversed-phase high performance liquid chromatography]

A method of separation and quantitation of sodium cyclamate in foods by ion-pair reversed-phase high performance liquid chromatography is described. Sodium cyclamate can be separated on ODS column at room temperature by using a mobile phase of V(methanol):V(water, containing ion-pair reagent) = 30:70 at 1 mL/min flow rate. The effects of ion-pair reagent and methanol on the retention of sodium cyclamate were studied. The samples were quantified with an ultraviolet detector operated at 205 nm. The calibration curve was linear in the range of 0.50-2.50 g/L with a correlation coefficient of 0.9996. The recoveries were 96.9%-101.7%. The detection limit was 0.05 g/L. This method is simple, rapid and sensitive.

[Treatment and outcome of cervical lymph nodal metastases of unknown primary sites]

OBJECTIVE

To ascertain the optimal management of cervical nodal metasta of unknown primary sites.

METHODS

The clinical data of 114 patients of cervical nodal metastases of unknown primary sites were retrospectively analyzed.

RESULTS

For metatic masses of the upper and/or middle part of the neck, the optimal approach varied depnding on the histologic type. Poorly-differentiated carcinoma was treated with radiotherapy, squamous-cell carcinoma was treated with radiotherapy plus surgery, while papillary adenocarcinoma was treated by combined radical thyroidectomy. Their 5-year survival rate was 45.2%, 53.8% and 62.5%, respectively. For metastatic masses in the supraclavicular region, chemotherapy was the first treatment of choice in all patients. In only 12 of the 114 patients (11.2%) the primary sites were found in the follow-up period.

CONCLUSION

For patients with cervical lymph node metastases from unknown primary sites, the management should be given according to the location of lymph node involved and histopathologic type of the tumor.

Near-field mapping of the emission distribution in semiconductor microdiscs

We have used a scanning near-field optical microscope to study the fluorescent light distribution in the near- and far-fields with two types of microdiscs, InGaP and GaN, fabricated in our laboratory. The InGaP microdisc has a radius of 2.5-5.0 microm, a thickness of 0.15-0.2 microm and a circular shape and the GaN disc has a radius of 5-8 microm with a thickness of 0.5-2 microm. Spontaneous emission enhancement in these microdiscs has been observed with emitting wavelengths of 650 and 550 nm respectively In both types of microdisc, the whispering-gallery mode (WCM) has been observed on the top surface using near-field optical and far-field microscopic methods. However, due to the different disc structures and optical confinements, the light distributions of the type types of disc are quite different. In the case of the InGaP disc, WGM is the dominant mode with a mixture of other modes. Interference-like ring intensities have been observed both inside the disc surface and outside, with a period ratio of 1:2. In addition, the propagating waves emitted from the side of the disc have been collected for the first time by using near-field optical microscopy. A theoretical calculation based on the theory of optical modes in microdisc lasers confirmed this observation. It also predicted the behaviour of the electric field distribution (transverse electric) inside and outside the disc, as well as the period of the wave propagation. In contrast, the near-field mapping of the GaN fluorescence showed not only a ring-like emission intensity along the circumference of the disc, an indication of WGM, but also an even intensity distribution inside the disc. This can be explained as the combination of the WGM with the Fabry-Perot mode of multi-reflection between the GaN layer and the substrate. The results also demonstrate the potential application of near-field optics to explore the light emission mode of a microdisc on a nanometre scale.

Induction of a secreted protein by the myxoid liposarcoma oncogene

The TLS-CHOP oncoprotein, found in the majority of human myxoid liposarcomas, consists of a fusion between the transcription factor CHOP/GADD153 and the N terminus of an RNA-binding protein TLS/FUS. Clinical correlation and in vitro transformation assays indicate that the N terminus of TLS plays an important role in oncogenesis by TLS-CHOP. Until now, however, the only activity attributed to the oncoprotein is that of inhibiting the binding of transcription factors of the C/EBP class to certain adipogenic target genes, a function that TLS-CHOP shares with the nononcogenic CHOP protein. Here we report the isolation of a gene, DOL54, that is activated in primary fibroblasts by the expression of TLS-CHOP. DOL54 is expressed in the neoplastic component of human myxoid liposarcomas and increases the tumorigenicity of cells injected in nude mice. Activation of DOL54 requires an intact DNA-binding and dimerization domain in TLS-CHOP, a suitable cellular dimerization partner, and depends on the TLS N terminus. Normal adipocytic differentiation is associated with an early and transient expression of DOL54, and the gene encodes a secreted protein that is tightly associated with the cell surface or extracellular matrix. TLS-CHOP thus leads to the unscheduled expression of a gene that is normally associated with adipocytic differentiation.

Subcellular distribution and redistribution of Bcl-2 family proteins in human leukemia cells undergoing apoptosis

It has been suggested that the ratio of Bcl-2 family proapoptotic proteins to antiapoptotic proteins determines the sensitivity of leukemic cells to apoptosis. However, it is believed that Bcl-2 family proteins exert their function on apoptosis only when they target to the mitochondrial outer membrane. The vinblastine-resistant T-lymphoblastic leukemic cell line CEM/VLB100 has increased sensitivity to tumor necrosis factor-alpha (TNF-alpha)-induced cytochrome c release, mitochondrial respiratory inhibition, and consequently apoptosis, compared with parental CEM cells. However, there was no difference between the two cell lines in the expression of Bcl-2 family proteins Bcl-2, Bcl-XL, Bcl-XS, Bad, and Bax at the whole cell level, as analyzed by Western blotting. Bcl-2 mainly located to mitochondria and light membrane as a membrane-bound protein, whereas Bcl-XL was located in both mitochondria and cytosol. Similar levels of both Bcl-2 and Bcl-XL were present in the resting mitochondria of the two cell lines. Although the proapoptotic proteins Bcl-XS, Bad, and Bax were mainly located in the cytosol, CEM/VLB100 mitochondria expressed higher levels of these proapoptotic proteins. Subcellular redistribution of the Bcl-2 family proteins was detected in a cell-free system by both Western blotting and flow cytometry after exposure to TNF-alpha. The levels of Bcl-2 family proteins were not altered at the whole cell level by TNF-alpha. However, after exposure to TNF-alpha, Bax, Bad, and Bcl-XS translocated from the cytosol to the mitochondria of both cell lines. An increase in Bcl-2 levels was observed in CEM mitochondria, which showed resistance to TNF-alpha-induced cytochrome c release. By contrast, decreased mitochondrial Bcl-2 was observed in CEM/VLB100 cells, which released cytochrome c from the mitochondria and underwent apoptosis as detected by fluorescence microscopy. We conclude that mitochondrial levels of Bcl-2 family proteins may determine the sensitivity of leukemic cells to apoptosis and that, furthermore, these levels may change rapidly after exposure of cells to toxic stimuli.

[Gene cloning and expression of Mycobacterium leprae alpha 2 antigen]

OBJECTIVES

The recombinant alpha 2 antigen of M. leprae was prepared using the molecular biologic tools and the recombinant DNA expression technology.

METHODS

Screening of the M. leprae expression library was performed by the plaque hybridization technique. Nucleotide sequences were determined by dideoxy termination method.

RESULTS

The gene coding for alpha 2 antigen of M. leprae was cloned and characterized, and the complete nucleotide sequence data has been assigned in the GSDB, DDBJ, EMBL and NCBI nucleotide sequence databank. The over expression system of alpha 2 antigen gene in E. coli was constructed, and the recombinant alpha 2 antigen has been purified by amylose column chromatography at the purity of more than 95%. More than 10 mg of recombinant alpha 2 antigen has been obtained from 200 ml of liquid culture.

CONCLUSION

The recombinant alpha 2 antigen of M. leprae could be used as one of the specific antigens for the sero-diagnosis of leprosy.

Three-dimensional finite element analysis and comparison of stress distribution in overdentures supported with bar attachments and telescopic crowns

OBJECTIVE

To determine which one of the overdenture (OD) retainers was more beneficial to the abutments--the bar or the telescopic crown--and if a tooth could be used as an OD abutment when the supporting bone decreased to half of the root.

MATERIALS AND METHODS

The three-dimensional finite element method was used to investigate the stress distribution in a mandible with an overdenture supported by the roots of two canines. The two teeth were either connected with a bar attachment or restored with telescopic crowns, and were then restored with a complete overdenture. For each type of superstructure, the influence of bone height around the roots (no alveolar resorption and resorption to half of the root length) was analyzed under three loading conditions.

RESULTS

The most extreme stress values were located at the alveolar ridge crest of the bone around the root of the abutment. In the case of anterior loading, the largest compressive stress (LCS) in telescopic crown overdenture (TOD) was lower. When loaded posteriorly there was no obvious difference between bar attachment overdenture (BOD) and TOD. At the alveolar ridge crest around the root of the abutment, the stress value in the model with decreased bone level was higher than in the model with normal bone level, but the range was not significant.

CONCLUSION

1. In terms of stress in the alveolar bone, complete overdenture over telescopic crowns is more convenient than over bar attachments. 2. Stress increases as the height of the bone around the roots decreases, but the increment is less than 30%. It is important for an abutment with bone resorption to perform root amputation to obtain an acceptable crown/root ratio.

Increased insulin sensitivity and hypoglycaemia in mice lacking the p85 alpha subunit of phosphoinositide 3-kinase

The hallmark of type 2 diabetes, the most common metabolic disorder, is a defect in insulin-stimulated glucose transport in peripheral tissues. Although a role for phosphoinositide-3-kinase (PI3K) activity in insulin-stimulated glucose transport and glucose transporter isoform 4 (Glut4) translocation has been suggested in vitro, its role in vivo and the molecular link between activation of PI3K and translocation has not yet been elucidated. To determine the role of PI3K in glucose homeostasis, we generated mice with a targeted disruption of the gene encoding the p85alpha regulatory subunit of PI3K (Pik3r1; refs 3-5). Pik3r1-/- mice showed increased insulin sensitivity and hypoglycaemia due to increased glucose transport in skeletal muscle and adipocytes. Insulin-stimulated PI3K activity associated with insulin receptor substrates (IRSs) was mediated via full-length p85 alpha in wild-type mice, but via the p50 alpha alternative splicing isoform of the same gene in Pik3r1-/- mice. This isoform switch was associated with an increase in insulin-induced generation of phosphatidylinositol(3,4,5)triphosphate (PtdIns(3,4,5)P3) in Pik3r1-/- adipocytes and facilitation of Glut4 translocation from the low-density microsome (LDM) fraction to the plasma membrane (PM). This mechanism seems to be responsible for the phenotype of Pik3r1-/- mice, namely increased glucose transport and hypoglycaemia. Our work provides the first direct evidence that PI3K and its regulatory subunit have a role in glucose homeostasis in vivo.

[Gas chromatography-infrared spectroscopy(GC-IR) analysis of the oxidation products of cyclohexene]

Gas chromatography-infrared spectroscopy technique integrates the excellent resolution ability of GC with the structural information of IR. Based on the GC and IR spectra, the complicated products of a reaction can be analyzed quantitatively and qualitatively. From the analysis of the products, the reaction process and its mechanism can be elucidated. In this work, analysis by GC-IR of the oxidation products of cyclohexene catalyzed by zeolite TS-1 in H2O2 was performed. The products are 2-cyclohexenone, 2-cyclohexen-1-ol and 2,3-epoxy-1-cyclohexanone. 2,3-Epoxy-1-cyclohexanone is an unexpected product. It must be a further oxidation product of 2-cyclohexenone. From the analysis, the reaction mechanisms were presumed.

Differential regulation of p21 by p53 and Rb in cellular response to oxidative stress

Oxidative stress to mammalian cells causes cellular damage and triggers inducible cellular responses leading to cell death by apoptosis. In this paper, we report that p53 was required for programmed cell death induced by oxidative stress in both mouse and human cells and that p53 transactivation was involved in induction of oxidative cell death. Furthermore, we show that p21 was highly responsive to oxidative stress in a p53-dependent manner and that ectopic expression of p21 could increase cellular susceptibility to oxidative stress in the absence of p53. However, p21 was not required for p53-directed oxidative cell death because mouse embryo fibroblasts MEFs lacking p21(p21-/- MEFs) were still susceptible to oxidative cell death. Interestingly, bax, a cell-death mediator regulated by p53, was overexpressed in p21-/- MEFs that underwent cell death by oxidative stress, suggesting a compensation for loss of p21 that may be responsible for the existence of cell-death responses in p21-knockout mouse fibroblasts. Finally, we provide evidence that the retinoblastoma gene product (Rb) is a negative regulator of p21 and a repressor of the cellular apoptotic process. Because p21 is regulated by p53 positively and by Rb negatively, p21 may be a link between p53 and Rb in determining cell fate after oxidative damage.

p53-mediated germ cell quality control in spermatogenesis

Spontaneous germ cell death is a common cellular process in the mammalian testis, although the function of this process during spermatogenesis is unclear. An investigation was undertaken to determine whether p53 serves as a mechanism in germ cell quality control by causing spontaneous germ cell death. Using an annexin V assay, lower levels of spontaneous apoptosis were found in the testes of p53-/- mice compared to p53+/+ mice. Propidium iodine staining revealed that the greatest reduction in apoptosis and the largest increase in cell numbers occurred in the tetraploid germ cell population of p53-/- mice. Microscopic examination of sperm morphology showed an increased percentage of abnormal forms in p53-/- mice. Furthermore, p53-/- mice sired fewer offspring than p53+/+ mice did when both groups were mated with p53+/+ females. These results suggest that p53 mediates spontaneous testicular germ cell apoptosis and failure to remove defective germ cells by this mechanism results in increased percentages of abnormal sperm and reduced fertility. p53-mediated apoptosis may be an effector of cellular proofreading that acts to maintain the cellular integrity of germ cells during spermatogenesis.

[Low temperature FTIR study of the structure of ruthenium polyhydrides]

A novel compound of Ru2H4 (CO) (PPh3)4 (A) is synthesized under hydrogen atmosphere. An in situ infrared apparatus which can be operated at liquid nitrogen temperarure is established. The structural conversion of RuH4 (PPh3)3 between dihydrogen and dihydride is observed firstly at room temperature. It is suggested that a fluxional molecule between terminal and bridged hydrogen appears in (A) with temperature changes. H2 molecule coordinated in ruthenium complex is rather easy to be substituted by CO, N2 and small organic molecule, this property is very important for activing molecular hydrogen and using in hydrogenation of unsaturated compounds.

Stereoselective pharmacokinetics of chlorpheniramine and the effect of ranitidine

This single-dose, randomized, crossover study was carried out to investigate the potential effect of ranitidine on the pharmacokinetics of chlorpheniramine. The study also afforded an opportunity to add to the limited data currently available on the stereoselective pharmacokinetics of chlorpheniramine. Healthy subjects received a single oral 4 mg dose of racemic chlorpheniramine on two separate occasions: alone, and on day 6 of dosing with ranitidine 75 mg b.i.d. for 8 days. Serum concentrations and urinary recovery of (S)-(+)- and (R)-(-)-chlorpheniramine were unaffected by administration of ranitidine, indicating no pharmacokinetic drug-drug interaction. The observed chlorpheniramine pharmacokinetic data were consistent with previous data and indicated approximately 2.5-fold higher serum concentrations of the (S)-(+) enantiomer. Previously reported high variability in chlorpheniramine pharmacokinetics was greatly reduced by well-controlled food and fluid intake.