The nuclear matrix of Euglena gracilis (euglenophyta): a stage of nuclear matrix evolution?

Euglena gracilis cell was extracted sequentially with CSK-Triton buffer, RSB-Magik solution and DNase-As solution. DGD embedment-free electron microscopy showed that in the extracted nucleus there was a residual non-chromatin fibrous network. That it could not be removed by hot trichloroacetic acid further supported the idea that it was a non-histone, non-chromatin fibrous protein network, and should be the internal network of the nuclear matrix. After the sequential extraction, the nuclear membrane was removed, leaving behind a layer of lamina; the chromatin was digested and eluted from the dense chromosomes and residual chromosomal structures that should be chromosomal scaffold were revealed. Western blot analysis with antiserum against rat lamins showed that nuclear lamina of the cell possessed two positive polypeptides, a major one and a minor one, which had molecular masses similar to lamin B and lamin A, respectively. Comparing these data with those of the most primitive eukaryote Archezoa and of higher eukaryotes, it was suggested that the lower unicellular eukaryote E. gracilis already had the nuclear matrix structure, and its nuclear matrix (especially the lamina) might represent a stage of evolutionary history of the nuclear matrix.

[Yield increasing and water saving effect under different soil fertility improvements in wheat-corn intercropping field in Huabei Plain]

Water resource in agriculture in Huabei Plain has been increasingly reduced in recent years. In order to reduce water evaporation and improve water utilization efficiency, the field experiment on water saving under different soil fertility improvements was carried out in Huantai county, Shandong Province. The result showed that straw incorporation and organic fertilizer application could increase yield and save water clearly. Under the same amount of irrigation(250 mm), the field with all corn and wheat straw incorporation had a higher yield of 885 kg.hm-2 than the field without straw incorporation, and a higher water efficiency of 3.13. The field with all corn and wheat straw incorporation and organic fertilizer application had a higher yield of 1875 kg.hm-2 than the comparing field, with a higher water efficiency of 3.60. The field with wheat straw incorporation had a higher yield of 675 kg.hm-2 than the comparing field, with a higher water efficiency of 3.24. The field with wheat straw incorporation and organic fertilizer application had a higher yield of 1200 kg.hm-2 than the comparing field, with a higher water efficiency of 3.28.

Multidimensional reaction coordinate for the excited-state H-atom transfer in perylene quinones: importance of the 7-membered ring in hypocrellins A and B

The excited-state intramolecular H-atom transfer reactions of hypocrellins B and A are compared by using time-resolved absorption and fluorescence upconversion techniques. The hypocrellin B photophysics are well described by a simple model involving one ground-state species and excited-state forward and reverse H-atom transfer with a nonfluorescent excited state. We suggest that excited-state conformational changes are coupled to the H-atom transfer in hypocrellin B just as gauche/anti changes are coupled to the H-atom transfer in hypocrellin A.

[Determination of glycosylated hemoglobin in human erythrocytes by fast protein liquid chromatography system]

The chromatography method for analysis of glycosylated hemoglobin(HbA1c) in human erythocytes was established by using a fast protein liquid chromatography system(FPLC) and a Mono S column. The average intrabatch and interbatch coefficients of variations (n = 3) were 2.5% and 4.8%, respectively. There was a positive correlation between the results of FPLC and routine microcolumn method (r = 0.413, P < 0.02). Using FPLC method, the HbA1c levels in festing blood of 54 normal donors and 26 diabetics on admission were 4.6 +/- 1.19(%) and 10.2 +/- 3.45(%), respectively. A significant difference was found statistically between the results of two groups (t = 10.8, P < 0.01).

Overexpression of Fas-ligand by neuroblastoma: a novel mechanism of tumor-cell killing

BACKGROUND/PURPOSE

Binding of Fas ligand (Fas-L) to the membrane-bound Fas receptor incites a series of intracellular events that results in programmed cell death or apoptosis. Although this apoptotic phenomenon plays a key role in down-regulating cytotoxic T cells, the authors have shown previously that pancreatic beta cells (bTC) overexpressing Fas-L paradoxically undergo accelerated rejection that is dependent on a Fas/Fas-L interaction. This study evaluates whether a neuroblastoma (NB) cell line manipulated to overexpress Fas-L undergoes similar destruction and whether tumor-specific protective immunity can be produced.

METHODS

The authors transfected NB cells (SK-N-MC) with either mFas-L cloned into a pcDNA3.1/Zeo plasmid vector (NB/Fas-L) or with the vector alone (NB/control). Successful transfection of Fas-L was characterized by reverse transcription polymerase chain reaction (RT-PCR) and the ability of transfectants to induce apoptosis of Fas-sensitive T cells (Jurkat). Expression of Fas and Fas-L in untransfected NB clones was characterized by immunohistochemistry and RNase protection assay (RPA). Apoptosis was measured by FACScan analysis using an Annexin V assay. A total of 3x10(6) NB/control and NB/Fas-L cells were implanted subcutaneously into the hind leg of Balb/C SCID mice. Tumor-specific protective immunity was also tested in this model by inoculating mice with NB/Fas-L before implanting NB/control cells.

RESULTS

Zeocin resistance and RT-PCR confirmed successful transfection of Fas-L into NB cells. Fas Ligand transfectants induced apoptosis in 17.6%+/-2.9% of Fas-sensitive T cells, whereas controls induced apoptosis in only 2.8%+/-1.2% (P = .01, n = 3). Although Fas appears to be constitutively expressed by NB in low amounts, introduction of Fas-L into NB cells did not induce suicide or affect tumor cell growth in vitro. In vivo, NB cells expressing Fas-L failed to grow in SCID mice (n = 3), whereas controls grew rapidly in all animals until death (n = 3). NB/control cells implanted into the opposite leg of mice that rejected initial NB/Fas-L transfectants also grew rapidly (n = 3) implying no protective immunity.

CONCLUSIONS

Overexpression of Fas-L in NB clones targets such cells for rapid destruction even in immune compromised hosts, suggesting potential utility of Fas-L in combating NB. In this SCID mouse model, the observed effect is probably neutrophil mediated and does not provide tumor-specific protective immunity.

Differential apoptosis gene expression in pediatric tumors of the kidney

BACKGROUND/PURPOSE

Apoptosis, or programmed cell death, is essential in maintaining normal homeostasis of tissues. The process of apoptosis is controlled by numerous pro- and antiapoptotic factors. Variations in expression of such factors may account for some variations in tumor behavior. This study evaluates the expression of apoptotic mRNA species in pediatric renal tumors to determine whether a pattern of differential apoptosis gene expression correlates with tumor grade and type.

METHODS

Twenty-five frozen tissue specimens were obtained from patients undergoing biopsy or resection of pediatric renal tumors before chemotherapy: Wilms' tumor stage II (WT-II, n = 4); Wilms' tumor stage III/IV (WT-III/IV, n = 4); clear cell sarcoma of the kidney stage III (CCSK, n = 2); rhabdoid tumor of the kidney stage III/IV (RTK, n = 4); and normal kidney (NK, n = 11). An RNase Protection Assay (RPA) was performed for 19 pro- and antiapoptotic mRNA species to detect and quantify expression (percentage of GAPDH expressed). Expression of specific mRNAs of interest were confirmed by Western Blot (WB).

RESULTS

The expression of apoptotic mRNA species varied markedly between tumors. WT-II expressed greater amounts of proapoptotic receptor mRNA than CCSK or RTK. (Fas, 17.0+/-2.7% v. 2.5+/-0.5% v. 3.3+/-0.9%; P<.02; DR5, 77.0+/-8.8% v. 13.5+/-0.5% v. 27.0+/-4.8; P<.001; TNF-R, 71.3+/-17.0% v. 21.0+/-4.0% v. 29.0+/-5.0%; P<.07, respectively). Surprisingly, antiapoptotic factors (e.g., bcl-2 and bcl-xl) were not overexpressed in poor prognostic tumors (CCSK, RTK) compared with those with good prognosis (WT). Expression of TRAIL (a ligand for DR4 and DR5) was significantly lower in CCSK and RTK than in normal kidney (9.5+/-1.5% v. 56.1+/-10.1%; P = .01).

CONCLUSIONS

Proapoptotic receptors are expressed at greater levels in good prognostic tumors, and this finding is compatible with their clinical behavior. Knowledge of differential apoptotic gene expression is of potential value in predicting prognosis and treating such tumors with targeted ligands.

Multidimensional reaction coordinate for the excited-state H-atom transfer in perylene quinones: importance of the 7-membered ring in hypocrellins A and B

The excited-state intramolecular H-atom transfer reactions of hypocrellins B and A are compared by using time-resolved absorption and fluorescence upconversion techniques. The hypocrellin B photophysics are well described by a simple model involving one ground-state species and excited-state forward and reverse H-atom transfer with a nonfluorescent excited state. We suggest that excited-state conformational changes are coupled to the H-atom transfer in hypocrellin B just as gauche/anti changes are coupled to the H-atom transfer in hypocrellin A.

Functional expression in Pichia pastoris of human and rat intrinsic factor

Intrinsic factor (IF) has been expressed previously in Baculovirus with a yield (0.1-1 mg/l) that was inadequate for structural and metabolic studies. IF cDNAs were cloned into the shuttle vector pPIC9 of P. pastoris, and the proteins were induced and purified by cobalamin (Cbl) affinity chromatography. Expression of recombinant proteins revealed a major band of 49 kDa for both human and rat IF. Expression of human IF was achieved at 1040 mg/l, but of rat IF at only 1-2 mg/l. Reaction of human IF with a photo-activatable derivative of Cbl was demonstrated by Western blotting, and detection of IF fragments by anti-Cbl monoclonal antibody and by amino-terminal sequencing revealed at least three regions (residues 129-151, 234-254, and +294) linked to Cbl. Both recombinant human and rat [125I]IF-Cbl bound to rat and guinea pig brush border membranes with similar affinity, but the binding capacity of human IF for the rat receptor was only 10% compared with rat IF. All six amino acids within the previously identified N-terminal binding region of human IF were mutated to be identical to rat IF, but the resulting chimeric IF still bound poorly to rat membranes. Mutations of residues 26/27 (Glu26 to Asp and Asn27 to Gln) and 32/34 (Ser32 to Thr and Tyr34 to Arg) showed changes in both Ka and Vmax, with great effects on Vmax. In conclusion, P. pastoris is an expression system that produces functional human IF at a higher yield than in the baculovirus system. Cbl binding was directly demonstrated at multiple sites along the linear sequence of human IF. The receptor binding function of the amino terminal sequence 25 62 has been confirmed, but it is insufficient to reproduce all the features of IF-Cbl binding.

[Study on the antitumor effect of angiostatin on LA795 adenocarcinoma cells]

OBJECTIVE

To study the antitumor effect of angiostatin on LA795 adenocarcinoma cells inoculated on T739 mice.

METHODS

Affinity chromatography purified plasminogen was digested by pancreatic elastase and angiostatin was obtained by purifying the digestion with affinity chromatography and dialysis. T739 mice were inoculated with LA795 cells. Angiostatin was given to part of inoculated and uninoculated mice by intraperitoneal injection fourteen days after the inoculation. The treatment lasted 20 days and the size of tumor, survival period, behavior of the mice and pathology of lungs, livers and kidneys were observed.

RESULTS

The size of tumor decreased from (2.35 +/- 0.26) cm to (0.97 +/- 0.34) cm after angiostatin treatment. The number of metastases in lung was significantly fewer in angiostatin treated mice than in untreated ones, which lived much shorter. No obvious side effects were observed.

CONCLUSION

Angiostatin markedly inhibits the growth and metastasis of LA795 cells on T739 mice and no obvious side effects of angiostatin were found during the treatment.

Trellis-based R-D optimal quantization in H.263+

We describe a trellis-based algorithm which enables R-D optimum quantization decisions in the H.263+ video coding standard. The algorithm allows the quantization decisions for all coefficients in a block to be made jointly, and experiments conducted using H.263+ for video coding rates of 40-50 kbps show an average improvement of 3.5% in bitrate relative to implementations which follow the International Telecommunications Union (ITU) Test Model specifications in making quantization decisions.

Microfabricated isoelectric focusing device for direct electrospray ionization-mass spectrometry

A novel microfabricated device for isoelectric focusing (IEF) incorporating an optimized electrospray ionization (ESI) tip was constructed on polycarbonate plates using laser micromachining. The IEF microchip incorporated a separation channel (50 micro x 30 micro x 16 cm), three fluid connectors, and two buffer reservoirs. Electrical potentials used for IEF focusing and electrospray were applied through platinum electrodes placed in the buffer reservoirs, which were isolated from the separation channel by porous membranes. Direct ESI-mass spectrometry (MS) using electrosprays produced directly from a sharp emitter "tip" on the microchip was evaluated. The results indicated that this design can produce a stable electrospray and that performance was further improved and made more flexible with the assistance of a sheath gas and sheath liquid. Error analysis of the spectral data showed that the standard deviation in signal intensity for an analyte peak was less than approximately 5% over 3 h. The production of stable electrosprays directly from microchip IEF device represents a step towards easily fabricated microanalytical devices. Microchannel IEF separations of protein mixtures were demonstrated for uncoated polycarbonate microchips. Direct microchannel IEF-ESI-MS was demonstrated using the microfabricated chip with an ion-trap mass spectrometer for characterization of protein mixtures.

The roles of free radicals in amyotrophic lateral sclerosis: reactive oxygen species and elevated oxidation of protein, DNA, and membrane phospholipids

To explore whether reactive oxygen species (ROS) play a role in the pathogenesis of amyotrophic lateral sclerosis (ALS), a unique microdialysis or microcannula sampling technique was used in mice transfected with a mutant Cu,Zn-superoxide dismutase (SOD1) gene from humans with familial ALS, mice transfected with the normal human SOD1 gene, and normal mice. We demonstrate for the first time that the levels of hydrogen peroxide (H(2)O(2)) and the hydroxyl radical ((.)OH) are significantly higher, and the level of the superoxide anion (O(2)(.-)) is significantly lower in ALS mutant mice than in controls, supporting by in vivo evidence the hypothesis that the mutant enzyme catalyzes (.)OH formation by the sequence: O(2)(.-) --> H(2)O(2) --> (.)OH. This removes doubts regarding the relevance of elevated ROS in FALS raised by in vitro experiments. The levels of oxidation products are also significantly higher in the mutant mice than in controls, consistent with some previous reports. Only the superoxide concentration differs between two controls among all the measurements. Our findings correlate in vivo a gene mutation to both elevated H(2)O(2) and (.)OH and increased oxidation of cellular constituents. The elevated H(2)O(2) in mutant mice indicates impairment of its detoxification pathways, perhaps by changed interactions between SOD1 and H(2)O(2) detoxification enzymes.-Liu, D., Wen, J., Liu, J., Li, L. The roles of free radicals in amyotrophic lateral sclerosis: reactive oxygen species and elevated oxidation of protein, DNA, and membrane phospholipids.

[Effect of replenishing liver and kidney, supplementing qi and activating blood circulation recipe on proliferation and relevant gene expression of vascular smooth muscle cells]

OBJECTIVE

To study the effect of replenishing Liver and Kidney, supplementing Qi and activating blood circulation recipe (TCM) on the proliferation and relevant gene expression of vascular smooth muscle cells (VSMC).

METHODS

Using 3H-TdR incorporation to investigate the VSMC proliferation, using Northern blotting and reverse Polymerase Chain Reaction (RT-PCR) to detect the effect of serum with TCM on induced NO synthase (iNOS), endothelin (ET) induced c-jun and proliferation cell nucleus antigen (PCNA) gene expression.

RESULTS

The 3H-TdR incorporation value of VSMC treated by serum with TCM was lower than that of control serum (P < 0.05). Rich iNOS mRNA was detected in the VSMC stimulated by serum with TCM. Expressions of c-jun and PCNA gene induced by ET in the VSMC were significantly inhibited by serum with TCM.

CONCLUSION

The TCM could significantly inhibit VSMC proliferation.

Activation of pelvic afferent nerves from the rat bladder during filling

This short paper has reviewed current information on the physiology of bladder mechanoreceptors. Afferents in the bladder mucosa appear to be sensitive to distension but not to contraction of the viscus, and are also sensitive to the chemical composition of the bladder contents. Evidence is provided that suggest that Neurokinin A is released from primary afferent endings in the submucosa and is involved in both the normal response to distension, and the sensitization process. The results suggest that the low threshold mechanoreceptors are polymodal, and are modulated by various mediators, including some peptides that may originate from the sensory endings themselves, and that these mediators may be active during normal filling.

Pig xenogeneic antigen modification with green coffee bean alpha-galactosidase

Green coffee bean alpha-galactosidase can cleave the terminal alpha-galactose (alphaGal) on oligosaccharides that form the major antigen on pig endothelial cells recognized by primate-specific antibodies. Studies have been made of the conditions under which it is functional (e.g. temperature, pH) and of its biochemical and immunologic effects. Pig-to-rhesus monkey vein transplants were studied to identify the efficiency of the enzyme in delaying hyperacute rejection. When a graft became occluded, biopsies were taken for light microscopy (hematoxylin and eosin), scanning electron microscopy (SEM) and immunostaining with Griffonia simplicifolia IB4 lectin (GSIB4), and for IgM, IgG and C3. alpha-Galactosidase was stable for 72-96 h and was effective at 4 degrees C and pH 6.9 (conditions of human liver graft storage), although better function was obtained at 20 degrees C and pH 6.5. Using the porcine PK15 cell assay, the cytotoxicity of human serum was reduced after treatment of the pig cells with the enzyme. In vitro studies demonstrated that porcine veins treated with alpha-galactosidase lost endothelial expression of the Gal epitope within 30 min. SEM, however, demonstrated endothelial damage beginning within 2 h, probably caused by the alpha-galactosidase, as no damage was found in phosphate-buffered saline-treated veins, where the Gal epitope was preserved for >3 h. No change was found in either group on light microscopy. In vivo studies demonstrated that patency of the alpha-galactosidase-treated veins (mean 2.5 h) was longer than that of untreated veins (0.23 h) (P < 0.01). Biopsies showed no GSIB4 lectin staining for alpha-Gal epitopes and much less IgM and C3 deposition in the treated group. Light microscopy and SEM demonstrated more severe endothelial damage, hemorrhage, and fibrin formation in the untreated group. Galactosidase is effective in removing the terminal alphaGal and delays the onset of hyperacute rejection of pig veins transplanted into monkeys. However, its effect is temporary and, on its own, its use is unlikely to prolong survival of pig organs transplanted into primates sufficiently to be of clinical value.

Pollen ultrastructure of Panax(the ginseng genus, Araliaceae),an eastern Asian and eastern NorthAmerican disjunct genus

Pollen of ten species of Panax and six species of Aralia was examined in light microscopy and scanning and transmission electron microscopy. Grains of both genera have similar complex apertures, short columellae, and overlapping tectal sculptures, suggesting a close relationship. Most species of Panax have pollen characterized by striato-reticulate tecta, short columellae, thick foot layers, costa ectocolpi, and lalongate endoapertures. The eastern North American P. trifolius, commonly known as the dwarf ginseng, has a distinctive pollen morphology and exine structure, supporting the hypothesis of its phylogenetically isolated position. Pollen of the eastern Asian P. ginseng (ginseng) can be distinguished from the eastern North American P. quinquefolius (American ginseng) by differences in ultrastructure. The monophyly of the three medicinally important species, P. ginseng, P. notoginseng, and P. quinquefolius, suggested by triterpenoid data, is not supported by pollen data. The results of the pollen study are generally congruent with those from the sequences of nuclear ribosomal DNA.

[Design of CXLY-II low frequency magnetic fields pulse generator]

An experimental device, low frequency magnetic fields pulse generator, has been designed and accomplished in our department. It can provide low frequency magnetic fields pulse with the intensity from 150mT to 800mT and the frequency from 0 to 100Hz. This device is easy to operate and performs reliably. It can stably work for a long time and has been successful used in the experiment of magnetic biological effect.

Elevation of hydrogen peroxide after spinal cord injury detected by using the Fenton reaction

To reveal whether reactive oxygen species (ROS) play a role after spinal cord injury, we developed a unique method for assaying hydrogen peroxide (H2O2) and determined the time course of its concentration changes following impact injury to the rat spinal cord. Microdialysis was used to sample H2O2 in the extracellular space and the dialysates were collected into a vial containing salicylate and ferrous chloride (FeCl2). H2O2 collected in the vial was converted to hydroxyl radicals (*OH) by FeCl2 catalysis. 2,3- and 2,5-dihydroxybenzoic acid produced by reaction of *OH with salicylate in the collecting vial were measured by HPLC and calibrated to H2O2 concentrations. The postinjury levels of H2O2 were significantly increased (p = 0.02) for over 11 h. FeCl2 administered through the dialysis fiber catalyzes H2O2 conversion in the cord to *OH. This *OH does not reach the collecting vial due to its extremely short lifetime (nanoseconds). The reduced H2O2 levels in the vials validate the measurement of H2O2. The relatively long-lasting formation of H2O2 and superoxide reported herein and previously suggests that ROS may be important in secondary spinal cord damage and that removal of ROS may be a realistic treatment strategy for reducing injury caused by free radicals.

High-mass-measurement accuracy and 100% sequence coverage of enzymatically digested bovine serum albumin from an ESI-FTICR mass spectrum

The application of Fourier transform ion cyclotron resonance (FTICR) mass spectrometry to the analysis of polypeptide mixtures resulting from proteolytic digestion is described. A new 11.5-T FTICR mass spectrometer has been applied for the analysis of tryptic digestion mixtures of the protein bovine serum albumin (BSA). The improved cyclotron frequency stability and reduced frequency shifts observed over a wide range of trapped ion population sizes provide the ability to signal average spectra without degrading mass measurement accuracy, requiring internal calibration or advanced data processing schemes to compensate for variations in ion cyclotron signals brought about by different population sizes. A total of 100 spectra were signal-averaged leading to the observation of a total of 123 isotope distributions with a signal-to-noise ratio greater than 3:1. From those distributions, 86 can be ascribed to tryptic fragments of BSA on the basis of mass measurement errors of 10 ppm or less. Of these, 71 were within 2 ppm error limits corresponding to complete amino acid sequence coverage and an average error of 0.77 ppm. These results indicate that high-accuracy measurements are feasible for a large number of species detected simultaneously without the necessity for internal calibration and indicate the potential of such measurements, when combined with chromatographic separations, for facilitating more rapid identification of large numbers of proteins.

Ryanodine and inositol trisphosphate receptors are differentially distributed and expressed in rat parotid gland

The present study examines the cellular distribution of the ryanodine receptor/channel (RyR) and inositol 1,4,5-trisphosphate receptor (InsP3R) subtypes in parotid acini. Using fluorescently labelled 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene-3-propionic acid glycyl-ryanodine (BODIPYtrade mark-ryanodine) and confocal microscopy, RyRs were localized primarily to the perinuclear region (basal pole) of the acinar cell. Ryanodine, Ruthenium Red, cAMP and cADP ribose (cADPR) competed with BODIPY-ryanodine, resulting in a reduction in the fluorescence signal. However, inositol 1,4, 5-trisphosphate [Ins(1,4,5)P3] did not alter the binding of BODIPY-ryanodine. Using receptor-subtype-specific antisera, InsP3Rs (types I, II and III) were located predominantly in the apical pole of the parotid cell. The presence of these three subtypes was confirmed using reverse transcriptase PCR with RNA-specific oligonucleotide probes. Binding studies using a parotid cell-membrane fraction identified and characterized RyRs and InsP3Rs in terms of binding affinity (Kd) and maximum binding capacity (Bmax) and confirmed that cADPR displaces ryanodine from its binding sites. Ruthenium Red and 8-Br-cADP-ribose blocked Ca2+ release in permeabilized acinar cells in response to cADPR and cAMP or forskolin, whereas Ins(1,4,5)P3-induced Ca2+ release was unaffected. The localization of the RyRs and InsP3Rs in discrete regions endow broad areas of the parotid cell with ligand-activated Ca2+ channels. The consequences of the dual activation of the RyRs and InsP3Rs by physiologically relevant stimuli such as noradrenaline (norepinephrine) are considered in relation to Ca2+ signalling in the parotid gland.

Photophysics of hypericin and hypocrellin A in complex with subcellular components: interactions with human serum albumin

Time-resolved fluorescence and absorption measurements are performed on hypericin complexed with human serum albumin, HSA (1:4, 1:1 and approximately 5:1 hypericin: HSA complexes). Detailed comparisons with hypocrellin A/HSA complexes (1:4 and 1:1) are made. Our results are consistent with the conclusions of previous studies indicating that hypericin binds to HSA by means of a specific hydrogen-bonded interaction between its carbonyl oxygen and the N1-H of the tryptophan residue in the IIA subdomain of HSA. (They also indicate that some hypericin binds nonspecifically to the surface of the protein.) A single-exponential rotational diffusion time of 31 ns is measured for hypericin bound to HSA, indicating that it is very rigidly held. Energy transfer from the tryptophan residue of HSA to hypericin is very efficient and is characterized by a critical distance of 94 A, from which we estimate a time constant for energy transfer of approximately 3 x 10(-15) s. Although it is tightly bound to HSA, hypericin is still capable of executing excited-state intramolecular proton (or hydrogen atom) transfer in the approximately 5:1 complex, albeit to a lesser extent than when it is free in solution. It appears that the proton transfer process is completely impeded in the 1:1 complex. The implications of these results for hypericin (and hypocrellin A) are discussed in terms of the mechanism of intramolecular excited-state proton transfer, the mode of binding to HSA and the light-induced antiviral and antitumor activity.

Overexpression of Fas ligand does not confer immune privilege to a pancreatic beta tumor cell line (betaTC-3)

BACKGROUND

Fas ligand (Fas-L) is thought to provide immune privilege to specific tissues and tumors by inducing an apoptotic signal of cytotoxic T cells expressing its Fas receptor. Purpose. The purpose of this work was to evaluate whether an immortalized insulin-secreting cell line (betaTC-3) gains immune privilege by inducing overexpression of Fas-L.

METHODS

A lipofection technique was used to transfect a betaTC-3 tumor cell line with a plasmid (pcDNA3.1/Zeo) carrying the Fas-L gene and a zeocin resistance gene. Insertion of Fas-L into betaTC was characterized by reverse transcription polymerase chain reaction (RT-PCR) and the ability of transfectants (betaTC-3/Fas-L) to induce apoptosis of Fas-sensitive T cells. Transfectants and control cells were tested for insulin secretion following which 1 x 10(6) insulin-secreting betaTC-3 and betaTC-3/Fas-L cells were subcutaneously implanted into syngeneic, allogeneic, and Fas mutant (lpr) syngeneic mice. Survival of the insulin-secreting cells was then determined by monitoring serum glucose levels in recipients.

RESULTS

Successful transfection of vector resistance gene was achieved in the transfected betaTC-3 cells, which was confirmed by zeocin resistance. RT-PCR in resistant Fas-L clones confirmed the transcription of Fas-L, which was absent in controls. Fas-L transfectants induced 20 +/- 4.2% apoptosis of Fas-sensitive T cells, while controls induced 3.47 +/- 2.3% by flow cytometry (P = 0.04, n = 3). Insulin secretion was equivalent in both betaTC-3 and betaTC-3/Fas-L cells. Syngeneic mice implanted with control betaTC-3 cells died within 3 weeks from hypoglycemia due to overgrowth of betaTC-3 tumor. Implanted Fas-L transfected betaTC-3 cells were killed and had no effect on glycemic status except in Fas mutant hosts, where tumors formed in two of three mice.

CONCLUSIONS

Despite the ability of transfected betaTC-3 cells to induce apoptosis of T cells in vitro, expression of Fas-L provided no immune privilege to these cells in vivo, but paradoxically induced killing of betaTC-3 cells even in syngeneic hosts.

[Influence of flavonoid of Astragalus membranaceus's stem and leaves on the function of cell mediated immunity in mice]

OBJECTIVE

To investigate the immune regulation of flavonoid of Astragalus membranaceus's stem and leaves (FAM).

METHODS

Changes of total T cell count and subsets in mice were determined by monoclonal antibody assay before and after treatment with FAM, and the LAK activity was tested simultaneously by isotope technique.

RESULTS

FAM could promote the proliferation of lymphocytes induced by ConA, raise the T cell count and regulate the T cell subsets disorder, elevate the LAK activity induced by IL-2.

CONCLUSION

FAM possesses the effect of immune stimulation and immune regulation in treating immunosuppressive mice. This study provides the experimental basis for clinical application of FAM.

[A study on digestion of Gal alpha (1,3) Gal on porcine vascular endothelial cells by alpha-galactosidase]

This study was designed to explore ways to prevent immune rejection in xenotransplantation. Porcine vein endothelial cells treated by alpha-Galactosidase were used to investigate the expression of Gal alpha(1,3) Gal on porcine vascular endothelial cells, and the morphology of vascular endothelial cells. The results showed that Gal alpha (1,3) Gal (alpha-Gal) on porcine vascular endothelial cells, which is the major epitome of xenoantigen, could be digested by alpha-Galactosidase within 30 minutes. No morphological changes were observed in the porcine vascular endothelial cells within a period of one hour after the treatment. This suggested that the treatment of porcine tissues with alpha-Galactosidase could be a new and effective way to prevent hyperacute rejection after xenotransplantation.

Effect of cytokines on in vitro bone resorption by cells isolated from giant cell tumor of bone

OBJECTIVE

To investigate the effect of cytokines on in vitro bone resorption by cells isolated from giant cell tumor of bone.

METHODS

Mononuclear stromal cells and multinucleated giant cells (MGC) were isolated from 11 cases of giant cell tumor of bone (GCT) and their bone resorption capability in an in vitro cell-bone resorption model were tested. Expressions of some cytokines were detected by immunohistochemistry, Western blotting analysis and Enzyme-linked immunoabsorbent assay (ELISA) in the GCT.

RESULTS

The results showed that MGCs of GCT had capability to resorb bone matrix directly. Fibroblast-like stromal cells (FC) could not only resorb bone matrix directly, but also secret unknown factors to facilitate bone resorption of MGC. Exogenous TNF-alpha could significantly increase the bone resorption by both kinds of stromal cells, while exogenous IL-1 did not. Expression rate of M-CSF and level of TNF-alpha in GCT were higher than in osteosarcoma and normal serum.

CONCLUSIONS

The characteristic bone resorption behavior of GCT might be caused by its three major cell components. The M-CSF and TNF-alpha could promote their bone resorption capability.

An integrated microfabricated device for dual microdialysis and on-line ESI-ion trap mass spectrometry for analysis of complex biological samples

A microfabricated dual-microdialysis device in a single integrated microfabricated platform was constructed using laser micromachining techniques for the rapid fractionation and cleanup of complex biological samples. On-line dual microdialysis and ESI-MS of biological samples was demonstrated using an ion trap mass spectrometer. The mass spectra obtained demonstrated the efficiency of dual microdialysis for removing both high-molecular-weight and low-molecular-weight species that interfere with effective ESI-MS analysis of target biopolymers. Signal-to-noise ratios were also greatly improved compared to direct sample infusion. In addition to its compactness, negligible dead volume, and robustness, the device can be used at a flow rate of only 200 nL/min, an order of magnitude lower than that obtained previously. This reduced sample consumption and improved sensitivity with ESI-MS. The results suggest the potential for integration of such microfabricated devices with other sample manipulations for the rapid ESI-MS analysis of complex biological samples.

[Skeletal metastasis pattern in non-small cell lung cancer and its related factors.]

BACKGROUND

To study the pattern of skeletal metastasis in non-small cell lung cancer and its associated factors.

METHODS

Six hundreds and thirty-eight patients with non-small cell lung cancer pathologically proved were retrospectively reviewed.

RESULTS

The percentage of skeletal metastasis was 35. 3 % in 638 cases. Multiple metastasis accounted for 201 cases. The sites of metastatic lesions for each patient was 3. 4. There was highly significant difference in different site of skeletal metastasis , for instance , thorax , spine , pelvis , limbs and skull in order of incidence ( P < 0. 005) . Bone metastasis rate of adenocarcinoma and adenosquamous carcinoma groups was remarkably higher than that of squamous cell carcinoma ( P < 0. 005) , which was highly significant higher in stage III - IV than that in stage I - II ( P < 0. 005) . The rate in patients with lower-differentiated lung cancer was also highly significant higher than those with well-differentiated cancer ( P < 0. 005) .

CONCLUSIONS

Skeletal metastasis is frequent in patients with lung cancer. Bone imaging should be performed routinely in all lung cancer patients , and it is helpful to estimate the stage and to make the therapeutic arrangement of lung cancer.

A well-collimated quasi-continuous atom laser

Extraction of sodium atoms from a trapped Bose-Einstein condensate (BEC) by a coherent, stimulated Raman process is demonstrated. Optical Raman pulses drive transitions between trapped and untrapped magnetic sublevels, giving the output-coupled BEC fraction a well-defined momentum. The pulsed output coupling can be run at such a rate that the extracted atomic wave packets strongly overlap, forming a highly directional, quasi-continuous matter wave.

[Research highlight of image reconstruction today]

In today's image processing researches, image reconstruction is a highlight. It includes the following several aspects: (1) reducing noise before reconstruction or after reconstruction under time-frequency constraints; (2) researches for reconstruction of motion organ; (3) image reconstruction from incomplete projection data; (4) direct volume reconstruction and 3-D image rendering; (5) researches for non-X-ray CT; (6) researches for parallel processing system of CT. In this paper, an introduction to these aspects is given.

Effects of tea polyphenols on cerebral lipid peroxidation, liver and renal functions in rats after repeated +Gz stress

OBJECTIVE

To observe the effects of repeated +10 Gz stress on cerebral lipid peroxidation, liver and renal function in rats and the prophylactic effects of antioxidant tea polyphenols (TP).

METHOD

Twenty-four male Wistar rats were randomly divided into three groups (n = 8, each): group A (control), group B (+10 Gz), and group C (TP). Group B and C were exposed to repeated +10 Gz stress (each for 30s, onset rate about 0.5 G/s, 3 times/d with +1 Gz 1 min intervals, 3 d/wk, 4 weeks in total), but group A was only submitted to +1 Gz. TP (200 mg/kg) was given orally in group C about 1 h prior to the +Gz experiment, while distilled water was given in group A and B. Lipid peroxidation in the brain, liver and renal functions and serum lipids were determined.

RESULTS

As compared with the control, lipid peroxidation in rat cerebral homogenate, mitochondria and cytoplasm was significantly increased (P < 0. 05), and serum creatinine concentration was markedly elevated after repeated +10 Gz stress (P < 0. 01). But, TP had significant inhibitory effect on +10 Gz stress induced peroxidative injury in rat brain and reduced the serum creatinine level. There were no differences of serum triglyceride and total cholesterol concentrations and glutamic-pyruvic transaminase activity among the three groups.

CONCLUSION

These results indicated that repeated high +Gz stress could bring about peroxidative injury in brain and harmful effect on renal function, and natural antioxidant TP had significant protective effects.

[Image displacement elimination method in tomosynthesis]

Computerized Tomography needs projected images from all directions, tomosynthesis doesn't need the information from all directions, but its reconstruction image is indistinct. In this paper, we introduce Frequency Domain Deconvolution Imaging(FDDI) which proposed recently. FDDI overcomes shortcoming of tomosynthesis, but FDDI's calculation is large, and its zero frequency will lose. We propose a new method-image displacement elimination method(IDEM), it overcome shortcomings of FDDI and can solve convolution equation set in space domain quickly.

The human telomerase catalytic subunit hTERT: organization of the gene and characterization of the promoter

Telomerase, the enzyme that synthesizes telomeric DNA, is not expressed in most human somatic cells but is activated with in vitro immortalization and during tumorigenesis, and repressed by cell differentiation. Of the two components of the core enzyme, the catalytic protein hTERT is limiting for activity. To investigate mechanisms of hTERT gene regulation, we have cloned genomic sequences encompassing the complete hTERT transcription unit. The hTERT gene consists of 16 exons and 15 introns spanning approximately 35 kb. Transient transfections of immortal human cells with potential regulatory 5' sequences linked to a reporter, combined with deletion analysis of these sequences, indicated that elements responsible for promoter activity are contained within a region extending from 330 bp upstream of the ATG to the second exon of the gene. Assays in different cell types have shown that the hTERT promoter is inactive in normal and in transformed pre-immortal cells, but, like telomerase, it is activated with cell immortalization. Sequence analysis revealed that the hTERT promoter is GC-rich, lacks TATA and CAAT boxes but contains binding sites for several transcription factors that may be involved in its regulation. The abundance of these sites suggests the possibility that hTERT expression may be subject to multiple levels of control and be regulated by different factors in different cellular contexts.

Conditional entropy coding of VQ indexes for image compression

Block sizes of practical vector quantization (VQ) image coders are not large enough to exploit all high-order statistical dependencies among pixels. Therefore, adaptive entropy coding of VQ indexes via statistical context modeling can significantly reduce the bit rate of VQ coders for given distortion. Address VQ was a pioneer work in this direction. In this paper we develop a framework of conditional entropy coding of VQ indexes (CECOVI) based on a simple Bayesian-type method of estimating probabilities conditioned on causal contexts, CECOVI is conceptually cleaner and algorithmically more efficient than address VQ, with address-VQ technique being its special case. It reduces the bit rate of address VQ by more than 20% for the same distortion, and does so at only a tiny fraction of address VQ's computational cost.

Scintigraphic measurement of regional gastrointestinal transit in the dog

Scintigraphic techniques can measure sequentially gastric emptying, small bowel transit, and colonic transit in humans, and comparable methods for experimental studies in animals would be useful. We developed such a method in dogs and examined the effects of prokinetic drugs on regional transit. Two isotopes were given to fasting dogs. Polystyrene pellets labeled with 99mTc were mixed in a can of dog food and 111In- labeled pellets were given in a gelatin capsule coated with a pH-sensitive polymer, designed to dissolve in the distal bowel. Gamma camera images were obtained for up to 24 h. Prokinetic drugs were given by intravenous injection. Duplicate baseline studies showed good agreement in seven dogs. In a second group (n = 4), intra- and interanimal variabilities were established. Two novel prokinetic drugs (AU-116 and AU-130) accelerated small bowel and colonic transit. A simple noninvasive method for measuring whole gut transit in dogs was developed and validated. Two new prokinetics accelerated small bowel and colonic transit.

Interactions between NFkappaB and its inhibitor ikappaB: biophysical characterization of a NFkappaB/ikappaB-alpha complex

The N-terminal domain (1-318 amino acids) of mouse NFkappaB (p65) has been purified to homogeneity from the soluble fraction of Escherichia coli cells expressing this protein. Its complex with a full-length ikappaB-alpha (MAD3, 1-317 amino acids) molecule was generated by binding the E. coli-derived ikappaB-alpha to the purified NFkappaB and purifying the complex by sequential chromatography. The stoichiometry of NFkappaB to ikappaB in the complex was determined to be 2 to 1 by light scattering and SDS-polyacrylamide gel electrophoresis. The secondary structure of the NFkappaB (p65) determined by Fourier-transform infrared (FTIR) spectroscopy is in good agreement with that of the p50 in the crystal structure of the p50/DNA complex, indicating that no significant structural change in NFkappaB occurs upon binding of DNA. The FTIR spectrum of the NFkappaB/ikappaB complex indicates that its secondary structure is composed of 17% alpha-helix, 39% beta-strand, 18% irregular structures, and 26% beta-turns and loops. By comparing these data to the FTIR data for NFkappaB alone, it is concluded that the ikappaB (MAD3) in the complex contains 35% alpha-helix, 27% beta-strand, 22% irregular structures, and 16% beta-turns and loops. Circular dichroism (CD) analysis of a shorter form of ikappaB (pp40) indicates that it contains at least 20% alpha-helix and that the ikappaB subunit accounts for nearly all of the alpha-helix present in the NFkappaB/ikappaB complex, consistent with the FTIR results. The stabilities of NFkappaB, ikappaB, and their complex against heat-induced denaturation were investigated by following changes in CD signal. The results indicate that the thermal stability of ikappaB is enhanced upon the formation of the NFkappaB/ikappaB complex.

Coexpression of G-CSF with an unglycosylated G-CSF receptor mutant results in secretion of a stable complex

Previously, we have shown that the entire extracellular domain of the granulocyte-colony stimulating factor receptor (sG-CSFr) produced in Chinese hamster ovary (CHO) cells forms a stable complex with its ligand G-CSF, at a stoichiometry of 2:2. A truncated receptor molecule consisting of the cytokine receptor homology domain and N-terminus Ig-like domain (Ig CRH) behaves quite similarly. Both of these forms of the receptor are highly glycosylated. To address the importance of glycosylation toward receptor activity and stability, and possibly obtain nonglycosylated receptor for crystallization, mutations were made to replace four Asn residues which are N-glycosylated in the truncated receptor. Virtually no receptor was recovered from conditioned media of CHO cells transfected with this mutant construct, although a high-level of mRNA coding for receptor was detected; this mRNA was translated as determined by Western blots of cell lysates. These results indicate that the translated product is apparently not secreted from these cells. Cells transfected with mutant receptor cDNA were cotransfected with a cDNA construct expressing G-CSF in which the single O-glycosylation site was eliminated by mutation. Upon fermentation of the cotransfectants, we observed a large amount of receptor-ligand complex in the conditioned media. The purified unglycosylated complex appeared to be of the same binding stoichiometry and approximate binding affinity as that of complex formed by addition of purified ligand and unmutated receptor. These results show that while glycosylation of sG-CSFr is not necessary for ligand binding, it appears to be crucial in folding and export from the cell.

Rat serum induces a differentiated phenotype in a rat parotid acinar cell line

To establish a continuous cell line, freshly prepared rat parotid acinar cells were stably transfected with a plasmid vector containing the SV40 large T antigen. The acinar origin of these cells was confirmed by Western blotting, enzyme analysis, and morphological analysis. Transformed cells grown in 10% rat serum showed a modest reduction in cell number after 7 days and a concentration- and time-dependent increase in amylase levels approximately 16 times greater than those observed in fetal bovine serum-treated cells. Ultrastructural analysis revealed that cells grown in rat serum harbored protein-filled secretory granules localized adjacent to the endoplasmic reticulum, and punctate amylase-specific immunofluorescence distributed throughout the cytoplasm was consistent with the presence of amylase in secretory organelles. Clonal cells express tissue-specific proline-rich proteins and the four protein kinase C isozymes present in primary culture. Carbachol and isoproterenol stimulated [3H]protein secretion and isoproterenol enhanced amylase secretion from cells grown in rat serum. Moreover, norepinephrine, carbachol, and substance P produced a time- and concentration-dependent rise in cytoplasmic Ca2+. This continuous cell line of parotid acinar cells, which after treatment with rat serum retains the basic structural and functional properties of primary culture cells, will be utilized as a model system for studying long-term biological processes that regulate parotid cell function.

Reconstitution of wild-type or mutant telomerase activity in telomerase-negative immortal human cells

Telomere shortening in human somatic cells and telomere maintenance in most human immortal cell lines and tumours correlate respectively with the absence and presence of telomerase, the enzyme that synthesizes telomeric DNA de novo . However, approximately 30% of in vitro immortalized human cell lines do not express this enzyme and maintain telomeres by an alternative pathway (ALT) that may also operate in some tumours. Human telomerase is a reverse transcriptase comprising minimally an RNA subunit (hTER) and a catalytic protein moiety (hTERT). Normal somatic cells retain expression of hTER but not of hTERT, and can be converted to a telomerase-positive phenotype by ectopic expression of the catalytic protein. We similarly have restored enzymatic activity to those ALT cell lines that retain hTER expression. We also report that in those ALT cells that are hTER negative, reintroduction of both hTER and hTERT is necessary and sufficient for conversion to telomerase positivity. Moreover, transfection of these cells with hTERT in conjunction with hTERs with a mutated template results in the expression of an enzyme with altered specificity. Reconstitution of telomerase activity in ALT cells, particularly an activity capable of synthesizing mutant telomeric DNA, may be exploited for the study of the ALT mechanism and its interaction with the telomerase-dependent pathway, and for assessing the effects of mutant telomeres on cell viability.

Phylogeny and biogeography of Aralia sect. Aralia (Araliaceae)

Aralia sect. Aralia (Araliaceae) consists of approximately eight species disjunctly distributed in Asia and North America. Phylogenetic and biogeographic analyses were conducted using sequences of the internal transcribed spacer regions of the nuclear ribosomal DNA. Aralia racemosa from eastern North America was sister to A. californica from western North America. Aralia cordata from eastern Asia did not form a species-pair relationship with the eastern North American A. racemosa. The two subspecies of A. racemosa formed a monophyletic group. Biogeographic analyses showed a close area relationship between eastern North America and western North America. The Himalayas were cladistically basal and eastern Asia was placed between the Himalayas and North America. The biogeographic analysis supported the origin of the eastern Asian and eastern North American disjunct pattern in Aralia sect. Aralia via the Bering land bridges. Comparisons with results of phylogenetic analyses of other genera suggested that (1) the floristic connection between eastern North America and western North America may be stronger than previously thought; and (2) the biogeographic patterns in the Northern Hemisphere are complex. Furthermore, a lack of correlation between sequence divergence values and phylogenetic positions was observed, suggesting the importance of a phylogenetic framework in biogeographic analyses.

[An etiological and serological study on Dengue epidemic in Guangdong Province]

In 1978-1995, Dengue fever epidemics(serotype 1-4) occurred in Guangdong Province. Among 9 species of mosquitoes found in the epidemic areas, the positive rate of virus isolation in Aedes albopictus was 20.69%, in Aedes aegypti 18.95%, in Culex quinquefasciatus 10.29%, Dengue viruses were not isolated in other 6 species of mosquitoes. The positive rate of virus isolation in the three species showed no significant differences (chi 2 = 2.77 P > 0.05). Aedes aegypti was the main transmitting vector in Hainan Island and Zhanjiang District, whereas Aedes albopictus was in the other epidemic areas. The positive rate of virus isolation within 3 days of disease onset was between 73.58% and 82.05%, but the virus could still be isolated on the 8th day of disease onset. The highest antibody positive rate from the patients' paired-sera was 93.89% and the lowest was 33.71%. IgM antibody could be detected 5 days after the disease onset in some cases, even on the 33rd day of disease onset. These results suggest that virus isolation by collecting patient's blood within 1-4 days of disease onset, or IgM antibody detection after 5 days of disease onset can be used as method for early and rapid diagnosis of the disease.

[The characteristics and significance of oncogenes expression in oval cells cultivated in vitro]

OBJECTIVE

To study the relationship between expression characteristics of oncogenes and transformation of the oval cells cultivated in vitro.

METHODS

Liver oval cells of SD rats induced by feeding with chemical carcinogen 3'-Me-DAB for four weeks were isolated using Percoll density gradient centrifugation. The cells were continuously cultivated in vitro and the dynamic characteristics of Ha-ras, Ki-ras and c-myc genes expression in the oval cells were detected using RNA-DNA slot blot hybridization.

RESULTS

During long term cultivation, the population doubling time of the cells became shorter and the percentage of aneuploidy chromosomes and colonies grown in soft agar increased. Ha-ras Ki-ras and c-myc were synchronically expressed in the oval cells from different passages.

CONCLUSION

The activation and synergistic over-expression of Ha-ras Ki-ras and c-myc had an important role in the proliferation and transformation of oval cells in vitro.

Localization of the binding site for transforming growth factor-beta in human alpha2-macroglobulin to a 20-kDa peptide that also contains the bait region

alpha2-Macroglobulin (alpha2M) functions as a major carrier of transforming growth factor-beta (TGF-beta) in vivo. The goal of this investigation was to characterize the TGF-beta-binding site in alpha2M. Human alpha2M, which was reduced and denatured to generate 180-kDa subunits, bound TGF-beta1, TGF-beta2, and NGF-beta in ligand blotting experiments. Cytokine binding was not detected with bovine serum albumin that had been reduced and alkylated, and only minimal binding was detected with purified murinoglobulin. To localize the TGF-beta-binding site in alpha2M, five cDNA fragments, collectively encoding amino acids 122-1302, were expressed as glutathione S-transferase (GST) fusion proteins. In ligand blotting experiments, TGF-beta2 bound only to the fusion protein (FP3) that includes amino acids 614-797. FP3 bound 125I-TGF-beta1 and 125I-TGF-beta2 in solution, preventing the binding of these growth factors to immobilized alpha2M-methylamine (alpha2M-MA). The IC50 values were 33 +/- 5 and 26 +/- 6 nM for TGF-beta1 and TGF-beta2, respectively; these values were comparable with or lower than those determined with native alpha2M or alpha2M-MA. A GST fusion protein that includes amino acids 798-1082 of alpha2M (FP4) and purified GST did not inhibit the binding of TGF-beta to immobilized alpha2M-MA. FP3 (0.2 microM) neutralized the activity of TGF-beta1 and TGF-beta2 in fetal bovine heart endothelial (FBHE) cell proliferation assays; FP4 was inactive in this assay. FP3 also increased NO synthesis by RAW 264.7 cells, mimicking an alpha2M activity that has been attributed to the neutralization of endogenously synthesized TGF-beta. Thus, we have isolated a peptide corresponding to 13% of the alpha2M sequence that binds TGF-beta and neutralizes the activity of TGF-beta in two separate biological assays.

[Cytotoxic effect of mitomycin C on the nonpigmented epithelium of ciliary body in rabbit eyes]

OBJECTIVE

To observe pathomorphological changes of nonpigmented epithelial cells (NECs) of ciliary body after local single application of mitomycin C (MMC) during sclerectomy in rabbit eyes, and to explore cytotoxic effect of MMC on ciliary body.

METHODS

A single five minutes intraoperative exposure to the agent MMC (0.2 mg/ml, 0.1 ml) was used during sclerectomy in rabbit eyes. The treated area was rinsed with 20 ml normal saline. The NECs of ciliary body at the operated area were observed under light microscope and transmission electron microscope on the 7th and 28th day postoperatively.

RESULTS

On the 7th day postoperatively, the NECs were swollen, and the intracellular abundant mitochondria were swollen and vacuolized. String pearls-like membrane-encapsulated vacuoles were present in the intervals of beta-cell membrane of the NECs. On the 28th day postoperatively, these damages were gradually recovered.

CONCLUSIONS

These findings suggest a toxic effect of MMC on the NECs of ciliary body, possibly that can decrease the aqueous production and intraocular pressure, even causing persistent hypotony.

CRP interacts with promoter-bound sigma54 RNA polymerase and blocks transcriptional activation of the dctA promoter

The cAMP receptor protein (CRP) is an activator of sigma70-dependent transcription. Analysis of the sigma54-dependent dctA promoter reveals a novel negative regulatory function for CRP. CRP can bind to two distant sites of the dctA promoter, sites which overlap the upstream activator sequences for the DctD activator. CRP interacts with Esigma54 bound at the dctA promoter via DNA loop formation. When the CRP-binding sites are deleted, CRP still interacts in a cAMP-dependent manner with the stable Esigma54 closed complex via protein-protein contacts. CRP is able to repress activation of the dctA promoter, even in the absence of specific CRP-binding sites. CRP affects both the final level and the kinetics of activation. The establishment of the repression and its release by the NtrC activator proceed via slow processes. The kinetics suggest that CRP favours a new form of closed complex which interconverts slowly with the classical closed intermediate. Only the latter is capable of interacting with an activator to form an open promoter complex. Thus, Esigma54 promoters are responsive to CRP, a protein unrelated to sigma54 activators, and the repression exerted is the direct result of an interaction between Esigma54 and the CRP-cAMP complex.

Duodenal motility in fasting dogs: humoral and neural pathways mediating the colonic brake

We have previously described a negative feedback loop that inhibits duodenal motility when nutrients are infused into the ileum and colon. In the present study, we examined the role of extrinsic innervation and plasma levels of peptide YY (PYY) in mediating this phenomenon. We perfused neurally intact (n = 5 dogs) or extrinsically denervated (n = 6 dogs) isolated loops of proximal colon with isomolar NaCl or a mixed-nutrient solution at 2 and 6 ml/min for 4 h during fasting or for 2 h beginning 15 min after a meal. Both rates of infusion with NaCl prolonged the cycle length of the duodenal migrating motor complex (MMC) in the group with neurally intact loops but not in the group with extrinsically denervated loops. Nutrient infusions increased the MMC cycle length in both groups. Integrated plasma concentrations of PYY were increased by nutrients but not by NaCl in both groups. These data suggest that increased volumes and unabsorbed nutrients in the proximal colon alter proximal small bowel motility. Volume-induced effects are mediated via extrinsic nerves, whereas nutrient-induced effects may be mediated by humoral factors, such as plasma PYY.

The potential of Betv1 homologues, a nuclear multigene family, as phylogenetic markers in flowering plants

Betv1 homologues are a ubiquitous group of genes in flowering plants encoding a class of highly conserved defense-related proteins and containing open reading frames from 465 to 480 bp. Betv1-like genes consist of two exons interrupted by an intron of 76-359 bp, with the intron position highly conserved. The pairwise p distance ranged from 0 to 0.583 among flowering plants. Within plant families, the ranges of the p distance were 0-0.403, 0-0.253, and 0.011-0.369, for Apiaceae, Betulaceae, and Fabaceae, respectively. The most striking feature of the betv1 gene phylogeny was that the multiple sequences from each plant family formed a monophyletic group and sequences from each species were generally more similar to each other than those from other species. The almost exclusive paralogous relationships of genes from the same species suggested that the genes of the multigene family underwent strong concerted evolution. Phylogenies of Betulaceae and Fabaceae inferred from betv1 gene trees were generally congruent with those based on morphology and other molecules. Betv1 homologues constitute potential phylogenetic markers at the intrafamilial level or among closely related families in flowering plants.