Replacement of glucose with N-acetylglucosamine in peritoneal dialysis fluid-experimental study in rats

BACKGROUND

Glucose is still used as an osmotic solute in peritoneal dialysis fluids, despite evidence of its local (peritoneal) and systemic toxicities. However a constant search is underway for a new, more biocompatible osmotic solute for peritoneal dialysis fluids.

OBJECTIVE

The present study evaluated N-acetylglucosamine (NAG) in a concentration of 220 mmol/L as an alternative to glucose for the osmotic solute in peritoneal dialysis fluid, during chronic peritoneal dialysis in rats.

METHODS

For 8 weeks, male Wistar rats were infused with glucose-based or NAG-based dialysis fluid. Intraperitoneal inflammation and peritoneal permeability and morphology were evaluated in all rats during the study.

RESULTS

Repeated intraperitoneal infusion of the NAG-based dialysis fluid resulted in a weaker intra-abdominal inflammatory reaction as compared with the reaction in rats infused with glucose-based dialysis solution. At the end of the study, the concentration of hyaluronan in the peritoneal interstitium obtained from NAG-treated rats was higher than that found in the interstitium taken from animals exposed to dialysis fluid containing glucose. Also, peritoneal permeability to total protein was lower in NAG-treated rats.

CONCLUSION

As an alternative to glucose, NAG used for the osmotic solute in peritoneal dialysis solution decreases the intraperitoneal inflammatory reaction induced by the process of peritoneal dialysis and, indirectly (owing to the increased hyaluronan content in the peritoneal interstitium), diminishes peritoneal permeability to protein.

[Researches on the nucleotide sequencing of the recombinant Sj 22.6 kDa antigen gene of Schistosoma japonicum]

AIM

To sequence the cloned gene in pGSj24 and to identify the encoded protein.

METHODS

The cloned gene in pGSj24 was digested from the recombinant plasmid by EcoRI, ligated into the M13mp19 vector and sequenced by automatic sequencer. The sequence was analyzed by Goldkey DNA and Protein Analytical Program and DNASIS Program.

RESULTS

The pGSj24 cloned gene was demonstrated to be 840 bp containing one opened reading frame (ORF) with an initiation codon ATG at position 23 nt and a termination codon TAA at position 596 nt, encoding a protein with a molecular weight of 22.6 kDa. At the upstream and downstream of the ORF there were termination codons, so the encoded protein was unable to be larger. However, there was a termination codon TAA at position 11 nt, suggesting why the 22.6 kDa protein expressed separately. The nucleotide sequence of the pGSj24 cloned gene shared 95% identity with that of the corresponding part of S. japonicum 22.6 kDa antigen gene, and 99.7% identity in the encoding part. The deduced amino acid sequence analysis showed a sequence motif known as EF-Hand calcium binding domain, several endoplasmic reticulum targeting sequences and microbodies C-terminal targeting signals. The possible antigen determinants were predicted within the amino acid fragments of 29-32aa, 63-68aa and 87-101aa.

CONCLUSIONS

The cloned gene in pGSj24 is the gene that encodes Sj22.6 kDa antigen.

[Changes on positive rate and distribution of Helicobacter pylori during progression of gastric cancer]

We observed changes on the positive rate and the distribution of helicobacter pylori (HP) in 7 case during early stage of gastric cancer and in 42 cases during middle-late stage of gastric cancer. The results showed that 1. the positive rate during early stage of gastric cancer was 57.1%, the positive rate during middle-rate stage of gastric cancer was 23.8%, 2. HP was not found within the gastric cancer lesions, 3. for HP positive cases, HP distribution during early stage of gastric cancer was more sparse than during middle-late stage of gastric cancer. These results suggested that HP can hardly live within the gastric cancer tissue, so the progression of gastric cancer is probably independent of HP. It may be a question that HP eradication can prevent later development of gastric cancer.

The correction of reflection intensities for incomplete absorption of high-energy X-rays in the CCD phosphor

It is shown that incomplete absorption of the X-ray beam in the phosphor of an area detector causes an incident-angle dependence of the recorded X-ray intensities. An energy scan of a SMART-6000 CCD (charge-coupled device) phosphor using synchrotron radiation shows the correction to be of importance above about 17 keV. Intensities of single reflections, each collected several times at different angles of incidence on the phosphor surface, show a pronounced angle-dependence at shorter wavelengths. Both conventional structural refinement and multipole charge density studies confirm that an oblique-incidence correction leads to improved quality of the results. Atomic displacement parameters will be systematically biased when the correction is not applied. For a λ = 0.394 Å data set, neglecting the correction gives rise to artifacts in the deformation density maps that are likely to lead to misinterpretation of the experimental results.

Detection of sequence variations in the adenomatous polyposis coli (APC) gene using denaturing high-performance liquid chromatography

We have evaluated the usefulness of denaturing high performance liquid chromatography (dHPLC) for scanning the adenomatous polyposis coli (APC) gene for point mutations, small deletions, and insertions. Our assay consists of 28 sets of primers to amplify the 15 exons of the APC gene. All PCR reactions were amplified simultaneously using the same reaction conditions in a 96-well format and then analyzed by dHPLC, using empirically determined optimum temperatures for partial fragment denaturation. Previously studied DNA specimens from 47 familial adenomatous polyposis (FAP) patients were analyzed by dHPLC and all mutations were correctly identified and confirmed by sequence analysis. This approach identified a single-base substitution in exon 6 and a 2-bp insertion in exon 15 that initially had not been detected by single-strand conformational polymorphism (SSCP) analysis. A novel mutation in exon 15 of the APC gene, 2065delG (codon 689) that had previously been undetected by the protein truncation test (PTT) was also identified by dHPLC. We present our validation studies of dHPLC technology for APC gene analysis in terms of sensitivity and specificity and compare it to current standard scanning technologies including PTT, SSCP, and conformational sensitive gel electrophoresis (CSGE).

Chiral synthesis and enzymatic resolution of (S)-(-)piperazine-2-carboxylic acid using enzyme alcalase

Enantiomerically pure (S)-piperazine-2-carboxylic acid was synthesized by kinetic resolution of methyl-4-(tert-butyroxycarbonyl)-piperazine-2-carboxylate using a low cost enzyme alcalase.

Inheritance and expression of the cry1Ab gene in Bt ( Bacillus thuringiensis) transgenic rice

The inheritance and expression patterns of the cry1Ab gene were studied in the progenies derived from different Bt ( Bacillus thuringiensis) transgenic japonica rice lines under field conditions. Both Mendelian and distorted segregation ratios were observed in some selfed and crossed F(2) populations. Crosses between japonica intra-subspecies had no significant effect on the segregation ratios of the cry1Ab gene, but crossing between japonica and indicainter-subspecies led to distorted segregation of the cry1Ab gene in the F(2)population. Field-release experiments indicated that the cry1Ab gene was stably transmitted in an intact manner via successive sexual generations, and the concentration of the Cry1Ab protein was kept quantitatively stable up to the R(6)generation. The cry1Ab gene, driven by the maize ubiquitinpromoter, displayed certain kinds of spatial and temporal expression patterns under field conditions. The content of the Cry1Ab protein varied in different tissues of the main stems, the primary tillers and the secondary tillers. Higher levels of the Cry1Ab protein were found in the stems, leaves and leaf sheaths than in the roots, while the lowest level was detected in grains at the maturation stage. The content of the Cry1Ab protein in the leaves peaked at the booting stage and was lowest at the heading stage. Furthermore, the Cry1Ab content of cry1Ab expression in different tissues of transgenic rice varied individually with temperature.

Arginine catabolism in lactating porcine mammary tissue

In vivo studies have shown that the uptake of plasma arginine by the lactating porcine mammary gland greatly exceeds the output of arginine in milk, but little is known about the metabolic fate of arginine in this organ. The objective of this study was to quantify arginine catabolism via arginase and nitric oxide synthase pathways in the mammary tissue of sows on d 28 of lactation. Mammary tissue slices (approximately 60 mg) were incubated at 37 degrees C for 1 h in 2 mL of Krebs bicarbonate buffer containing 0.5 or 2 mM L-[U-14C]arginine, and arginine metabolites were measured using HPLC and radiochemical techniques. Rates of arginine utilization were similar to rates of urea production. Proline, ornithine, urea, glutamate, glutamine, CO2 and polyamines (putrescine + spermidine + spermine) were formed from arginine, accounting for 46, 31, 17, 2.3, 1.5, 0.22, and 0.30%, respectively, of the metabolized arginine carbons. Relatively small amounts of arginine were utilized for nitric oxide and citrulline synthesis, with citrulline accounting for 2% of the metabolized arginine carbons. Production of all arginine metabolites increased with increasing extracellular arginine concentrations from 0.5 to 2 mM, indicating a high capacity for arginine degradation. Consistent with the metabolic findings, the activities of arginases, ornithine aminotransferase, and pyrroline-5-carboxylate reductase were high, whereas those of pyrroline-5-carboxylate dehydrogenase, ornithine decarboxylase, and nitric oxide synthases were relatively low, and there was no proline oxidase, ornithine carbamoyltransferase or pyrroline-5-carboxylase synthase activity in the mammary tissue. Our results demonstrate for the first time that proline, ornithine, and urea were the major products of arginine catabolism via the arginase pathway in lactating porcine mammary tissue and provide a biochemical basis to explain a relative enrichment of proline but a relative deficiency of arginine in sow's milk.

Inhibition of protein phosphatase-1 is linked to phosphorylation of p53 and apoptosis

p53 is a multifunctional protein and its activity can be modulated by phosphorylation and dephosphorylation. In this study, we sought to examine the notion that serine/threonine phosphatases (PP-1 and PP-2A) are active modulators of the p53-dependent apoptotic pathway. Exposure of neonatal rat cardiomyocytes to the established apoptotic agents, bafilomycin A1 (BAF) or staurosporine (STAU) induced apoptosis and caused a decrease in PP-1 activity of 35%. This response was restricted to apoptotic stimuli as treatment with phenylephrine neither decreased PP-1 and PP-2A activity nor induced DNA fragmentation in cardiomyocytes. The level of phosphorylated p53 was increased as a result of BAF or STAU-treatment. We further examined the effect of PP-1 inhibition on cardiomyocytes by the use of the phosphatase inhibitor, okadaic acid, and an antisense strategy. Okadaic acid (100 nM) resulted in a decrease in PP-1 activity of 45%, enhanced phosphorylation of p53, and stimulated apoptosis. Furthermore, overexpression of the antisense PP-1 catalytic subunit transcript caused a 44% decrease in expression of PP-1, with no change in the levels of the PP-2A catalytic subunit, and also evoked DNA fragmentation. Our data support the view that decreased activity of PP-1 is an important signaling event in the apoptotic process.

Increased myocardial Rab GTPase expression: a consequence and cause of cardiomyopathy

The Ras-like Rab GTPases regulate vesicle transport in endocytosis and exocytosis. We found that cardiac Rabs1, 4, and 6 are upregulated in a dilated cardiomyopathy model overexpressing beta(2)-adrenergic receptors. To determine if increased Rab GTPase expression can contribute to cardiomyopathy, we transgenically overexpressed in mouse hearts prototypical Rab1a, the small G protein that regulates vesicle transport from endoplasmic reticulum to and through Golgi. In multiple independent mouse lines, Rab1a overexpression caused cardiac hypertrophy that progressed in a time- and transgene dose-dependent manner to heart failure. Isolated cardiac myocytes were hypertrophied and exhibited contractile depression with impaired calcium reuptake. Ultrastructural analysis revealed enlarged Golgi stacks and increased transitional vesicles in ventricular myocytes, with increased secretory atrial natriuretic peptide granules and degenerative myelin figures in atrial myocytes; immunogold studies localized Rab1a to these abnormal vesicular structures. A survey of hypertrophy signaling molecules revealed increased protein kinase C (PKC) alpha and delta, and confocal microscopy showed abnormal subcellular distribution of PKCalpha in Rab1a transgenics. These results indicate that increased expression of Rab1 GTPase in myocardium distorts subcellular localization of proteins and is sufficient to cause cardiac hypertrophy and failure.

BMS-196085: a potent and selective full agonist of the human beta(3) adrenergic receptor

A series of 4-hydroxy-3-methylsulfonanilido-1,2-diarylethylamines were prepared and evaluated for their human beta(3) adrenergic receptor agonist activity. SAR studies led to the identification of BMS-196085 (25), a potent beta(3) full agonist (K(i)=21 nM, 95% activation) with partial agonist (45%) activity at the beta(1) receptor. Based on its desirable in vitro and in vivo properties, BMS-196085 was chosen for clinical evaluation.

A nationwide survey of post-operative instructions following uncomplicated phacoemulsification cataract surgery

PURPOSE

To determine the heterogeneity of post-operative instructions following uncomplicated phacoemulsification cataract surgery.

METHODS

A survey was sent to a random sample of 115 cataract centres in the United Kingdom. Eighty questionnaires were returned, corresponding to a response rate of 70%.

RESULTS

The time at which post-operative advice was given, the nature of post-operative problems, and advice regarding the instillation of post-operative eye drops were all very similar among centres. There was mild variability among centres in the advice given on post-operative analgesia, eye cleaning and hair washing. However, there were marked differences in the advice given to patients regarding how long an eyeshield should be worn, and also regarding daily activities such as lifting objects and driving. Thirty-five per cent of centres adopted a single post-operative review. No centre had more than three post-operative reviews for an uncomplicated phacoemulsification. The final refraction was conducted by at least 30% of centres within the first month, and by at least 92% within 2 months.

CONCLUSIONS

Phacoemulsification with a self-sealing tunnel is now the technique of choice for an uncomplicated cataract extraction and is increasingly conducted on a daycase basis. However, our survey reveals that there is considerable heterogeneity in the postoperative instructions given to patients following this procedure, and we would suggest that considerable benefits would result from further work in this area. Standard guidelines would not only benefit the patient in terms of improved patient education and rehabilitation, but would also result in economic benefits from reduced post-operative visits.

The tree shrew apolipoprotein C-I cDNA: sequence and its expression

A rabbit anti-serum to tree shrew apolipoprotein C-I (apo C-I) was used to screen an expression cDNA library constructed by us from tree shrew (TS) liver tissue. Two apo C-I cDNA clones were obtained. The longer one consists of 380 nucleotides, including 21 bp and 95 bp at the 5' and 3' end of the non-translated regions respectively, and a 264-bp fragment in an open reading frame encoding 88 amino acids prepropeptide which contains 26 amino acids of signal peptide and a mature protein (62 amino acids). Comparing the amino-acid sequence deduced from this cDNA with those of the published mammalian apo C-Is reveals that it shared some structural similarity with rat, mouse and dog apo C-I, but it had 5 more amino acids than that of human and baboon. The expression of apo C-I mRNA in 8 different tissues were also assayed with Northern blot. The results demonstrated that liver had the highest expression, intestine had much less expression and no expression in other tissues, which is much different from human and other species. This study has laid down a good foundation for further studying on the function and the stucture of tree shrew apo C-I gene.

Fitting pieces in the peripheral nerve puzzle

Findings from comparative microneurography are reviewed, i.e., data obtained by exploring human nerves with tungsten electrodes or concentric needle electrodes under similar conditions. It has emerged that activity in single myelinated fibers originates near nodes of Ranvier. Other data have shown that Ranvier nodes tend to cluster in certain regions of a fascicle and belong to fibers of the same modality which innervate the same skin area. This segregation involves all four main classes of myelinated low-threshold skin afferents. Fiber populations of the same modality may act as peripheral projection modules involved in somatosensory processing of tactile stimuli to cognitive levels. The fiber bundle arrangement of the nerves may be important for conserving functional gnosis in conditions where peripheral nerve fibers are lost. This organization may also be critical as a substrate to promote reinnervation after nerve cut followed by peripheral nerve suture. It is therefore less critical for an outgrowing fiber to find its exact distal counterpart. Even if misguided outgrowth occurs into the endoneurial tube of a neighboring distal fiber of the same modality with an adjacent receptive field, function can be reestablished. A precise nerve topography might also be of significance for obtaining a functionally satisfactory recovery after avulsion injuries treated by nerve root implantation into the spinal cord. Thus, there is in man an ordered nerve fiber organization, both in the periphery and in the CNS, which may have profound functional significance both under normal conditions and in disease.

A genome-wide analysis of Arabidopsis Rop-interactive CRIB motif-containing proteins that act as Rop GTPase targets

The plant-specific Rop family GTPases are versatile molecular switches in many processes during plant growth, development, and responses to the environment. To understand how Rop achieves its functional versatility in signaling, we performed a genome-wide identification of putative Rop targets using a combination of the yeast two-hybrid method, bioinformatic tools, and a robust functional assay in pollen. In this study, we have identified 11 Arabidopsis genes encoding novel proteins, termed RICs (for Rop-interactive CRIB motif-containing proteins), that contain a CRIB (for Cdc42/Rac-interactive binding) motif required for their specific interaction with GTP-bound Rop1. RICs are divergent and classified into five groups that share little sequence homology outside of the conserved Rop-interactive domain. Overexpression in tobacco pollen tubes of the nine Ric genes that are expressed in Arabidopsis pollen causes distinct phenotypes, implying distinct functions for various RICs. RIC3 (group III) and RIC4 (group V) both cause depolarized growth like Rop1 and display Rop1-enhanced localization to the tip of pollen tubes, suggesting that these RICs may be two distinct targets of Rop1. In contrast, RIC10 (group I) promotes pollen tube elongation but does not affect pollen tube growth polarity and shows Rop1-independent localization to the cytoplasm, suggesting that RIC10 may participate in a Rop1-independent pathway probably controlled by a different Rop. Expression of all other RICs causes various degrees of growth inhibition in pollen tubes. Furthermore, these inhibitory RICs also exhibit distinct patterns of localization in pollen tubes. Our results suggest that various RICs have evolved to interact with Rops differentially and to perform distinct functions in pollen tubes. Reverse transcriptase-mediated polymerase chain reaction analysis showed that six of the nine RICs are expressed in various parts of Arabidopsis plants. On the basis of these observations, we propose that RICs function as Rop GTPase targets that control various Rop-dependent signaling pathways in plants.

Developmental potential of porcine nuclear transfer embryos derived from transgenic fetal fibroblasts infected with the gene for the green fluorescent protein: comparison of different fusion/activation conditions

The in vitro developmental potential of porcine nuclear transfer (NT) embryos was evaluated. Oocytes were matured for 42-44 h, and metaphase II-oocytes were enucleated. Fetal fibroblasts infected with the enhanced green fluorescent protein (EGFP) gene were serum-starved for 3-5 days. A single cell was injected into the perivitelline space of the enucleated oocytes. The reconstructed oocytes were allocated to different fusion and activation conditions. In experiment 1, two different fusion/activation conditions were compared: two pulses of 1.2 kV/cm for 30 microsec (group A), or one pulse of 1.6 kV/cm for 30 microsec followed in 30 min by one pulse of 1.2 kV/cm for 30 microsec (group B). Parthenogenetic controls were created by using the group A parameter. The fusion rate in group A (mean +/- SEM, 68.4% +/- 3.9%) was higher (P < 0.05) than in group B (59.4% +/- 2.3%). The rates of cleavage (50.1% +/- 4.6% to 62.8% +/- 5.5%) were not different among control and treatment groups. However, the rate of parthenogenetic control embryos developing to the blastocyst stage (18.1% +/- 3.1%) was higher (P < 0.05) than the rate of NT embryos (5.9% +/- 1.7% and 4.9% +/- 2.5%). In experiment 2, we compared two pulses of 1.2 kV/cm (group C) versus two pulses of 1.3 kV/cm (group D). For two control groups, the same pulses as those given to group C or D, respectively, were supplied. The fusion rate in group D (70.6% +/- 4.2%) was higher (P < 0.05) than in group C (58.9% +/- 2.7%). The cleavage rates were not different among control and treatment groups (58.1% +/- 8.1% to 73.6% +/- 6.0%). However, the rate of embryos developing to the blastocyst stage in group D (3.5% +/- 1.7%) was lower (P < 0.05) than in controls and group C (11.4% +/- 2.0% to 16.4% +/- 1.1%). In experiment 3, we examined whether the presence of cytochalasin B (CB) during donor cell injection affects the development of NT embryos. The fusion rate of oocytes in the group with CB (78.4% +/- 1.4%) was higher (P < 0.05) than in the group without CB (70.9% +/- 0.2%). The cleavage rate of the control group (85.5% +/- 4.9%) was higher (P < 0.05) than those of the treatment groups (61.6% +/- 2.7% and 63.9% +/- 4.3%). However, the rates of embryos developing to the blastocyst stage (8.1% +/- 2.5% to 19.1% +/- 6.0%) and the mean cell number of blastocysts (29.4 +/- 5.2 to 45.7 +/- 6.4) were not different among control and treatment groups. Green fluorescence was observed at all stages in NT embryos. These results indicate that two pulses of 1.2 kV/cm are enough for fusion/activation of NT embryos to develop to the blastocyst stage, and that the presence of CB during donor cell injection is not necessary for early development of NT embryos.

A genome-wide analysis of Arabidopsis Rop-interactive CRIB motif-containing proteins that act as Rop GTPase targets

The plant-specific Rop family GTPases are versatile molecular switches in many processes during plant growth, development, and responses to the environment. To understand how Rop achieves its functional versatility in signaling, we performed a genome-wide identification of putative Rop targets using a combination of the yeast two-hybrid method, bioinformatic tools, and a robust functional assay in pollen. In this study, we have identified 11 Arabidopsis genes encoding novel proteins, termed RICs (for Rop-interactive CRIB motif-containing proteins), that contain a CRIB (for Cdc42/Rac-interactive binding) motif required for their specific interaction with GTP-bound Rop1. RICs are divergent and classified into five groups that share little sequence homology outside of the conserved Rop-interactive domain. Overexpression in tobacco pollen tubes of the nine Ric genes that are expressed in Arabidopsis pollen causes distinct phenotypes, implying distinct functions for various RICs. RIC3 (group III) and RIC4 (group V) both cause depolarized growth like Rop1 and display Rop1-enhanced localization to the tip of pollen tubes, suggesting that these RICs may be two distinct targets of Rop1. In contrast, RIC10 (group I) promotes pollen tube elongation but does not affect pollen tube growth polarity and shows Rop1-independent localization to the cytoplasm, suggesting that RIC10 may participate in a Rop1-independent pathway probably controlled by a different Rop. Expression of all other RICs causes various degrees of growth inhibition in pollen tubes. Furthermore, these inhibitory RICs also exhibit distinct patterns of localization in pollen tubes. Our results suggest that various RICs have evolved to interact with Rops differentially and to perform distinct functions in pollen tubes. Reverse transcriptase-mediated polymerase chain reaction analysis showed that six of the nine RICs are expressed in various parts of Arabidopsis plants. On the basis of these observations, we propose that RICs function as Rop GTPase targets that control various Rop-dependent signaling pathways in plants.

Isochorismate synthase is required to synthesize salicylic acid for plant defence

Salicylic acid (SA) mediates plant defences against pathogens, accumulating in both infected and distal leaves in response to pathogen attack. Pathogenesis-related gene expression and the synthesis of defensive compounds associated with both local and systemic acquired resistance (LAR and SAR) in plants require SA. In Arabidopsis, exogenous application of SA suffices to establish SAR, resulting in enhanced resistance to a variety of pathogens. However, despite its importance in plant defence against pathogens, SA biosynthesis is not well defined. Previous work has suggested that plants synthesize SA from phenylalanine; however, SA could still be produced when this pathway was inhibited, and the specific activity of radiolabelled SA in feeding experiments was often lower than expected. Some bacteria such as Pseudomonas aeruginosa synthesize SA using isochorismate synthase (ICS) and pyruvate lyase. Here we show, by cloning and characterizing an Arabidopsis defence-related gene (SID2) defined by mutation, that SA is synthesized from chorismate by means of ICS, and that SA made by this pathway is required for LAR and SAR responses.