[A study on the effect of rare earth metal ions on fluorescence spectra of the tryptophan using fluorescence spectroscopy]

Rare earth metal ions and tryptophan form ion-association complex in basic medium. The complex causes fluorescence quenching of tryptophan. Fluorescence emission of tryptophan and quenching caused by rare earth metal ions both reach a climax in H3BO4-HAc-H3PO4-NaOH at pH 10 to 11, and all rare earth metal ions have the approximate effects on fluorescence quenching of tryptophan. The molecular mode of complex of rare earth metal ions and tryptophan has been founded and mechanism of fluorescence quenching has been studied in this paper.

Dietary 4-HPR suppresses the development of bone metastasis in vivo in a mouse model of prostate cancer progression

The effects of the synthetic retinoid N-(4-hydroxyphenyl) retinamide (4-HPR) on prostate cancer metastasis in vivo were evaluated in the mouse prostate reconstitution (MPR) model. MPRs were produced by infection of either heterozygous (+/-) or nullizygous (-/-) p53-mutant fetal prostatic epithelial cells with the recombinant retrovirus Zipras/myc 9. Previous studies have documented that loss of p53 function potentiates metastasis in this model system. MPRs were grafted into homozygous (+/+) p53 male mice, fed a 4-HPR containing diet or a control diet and maintained until the status of tumor progression dictated sacrifice. Under these experimental conditions, treatment with 4-HPR did not have a significant effect on primary tumor wet weight for either p53 +/- or p53 -/- MPRs. For, p53 +/- MPRs the animals fed the 4-HPR diet had a slight improvement in survival and a significant reduction in the number of mesenteric metastases (P = 0.0477, t-test). Notably, in p53 +/- MPRs the incidence of metastasis to lumbar spine and sternum was 92% in the control animals compared to 54% in the 4-HPR treated animals (P = 0.035, chi2-test). In p53 -/- MPRs there was a trend toward a reduction in the number of soft tissue metastases to lung and liver in the 4-HPR group relative to the control diet group and a statistically significant reduction in the incidence of metastasis to bone was demonstrated in that 50% of control animals versus 30% of 4-HPR treated p53 -/- animals harbored bone metastases (P = 0 < 0.05, chi2-test). Cell lines were established from portions of the primary tumor and from selected metastatic deposits in each experimental group. Clonal analysis, by retroviral integration pattern, indicated increased clonal diversity in both the primary tumors and metastasis-derived cell lines from 4-HPR treated animals relative to the control animals. In vitro treatment with 4-HPR did not reveal discriminating differences between cell lines derived from primary tumors and bone metastases or control and treatment groups in regard to growth arrest or apoptotic responses. Overall these studies indicate limited anti-tumor and anti-metastatic activity in this highly aggressive in vivo mouse model of prostate cancer, yet 4-HPR treatment significantly suppressed the development of bone metastases in p53 +/- and p53 -/- MPRs revealing a novel and potentially clinically useful activity of this retinoid.

[Histopathological changes of prostate cancer after castration therapy and correlative factors]

OBJECTIVE

To study the histopathological changes of prostate cancer after castration therapy among Chinese and correlative factors.

METHODS

Needle biopsy specimens and prostatectomy specimens were obtained from 17 cases of prostate cancer and examined by light microscopy and image analysis system.

RESULTS

Glandular atrophy, cytoplasmic vacuolization, nuclear pyknosis, and relative increase of stroma could be seen after orchectomy. There was a close correlation between atrophy of neoplastic tissue in prostate gland and patients' age (P < 0.05). The atrophy of neoplastic tissue in prostate gland was not correlated with the serum PSA, tumor staging and grading before castration therapy (P > 0.05).

CONCLUSION

Castration is effective for treatment of prostate cancer, especially among the elderly patients. It is important for pathologists to recognize the histopathological changes in the prostectomy specimens made untypical by castration.

Role of arginine 216 in catalytic activity of murine Alpha class glutathione transferases mGSTAl-1 and mGSTA2-2 toward carcinogenic diol epoxides of polycyclic aromatic hydrocarbons

Murine class Alpha glutathione (GSH) transferase A1-1 (mGSTA1-1) is unique among mammalian Alpha class GSTs due to its exceptionally high catalytic activity toward (+)-anti-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene [(+)-anti-BPDE], which is the activated metabolite of an environmentally relevant carcinogen, benzo[a] pyrene (BP). However, the molecular basis for high catalytic activity of mGSTA1-1 toward (+)-anti-BPDE is not clear. In the present study, we demonstrate that an arginine residue at position 216, which is conserved in some but not all mammalian class Alpha GSTs, plays an important role in catalytic activity of mGSTA1-1 toward (+)-anti-BPDE and carcinogenic diol epoxides of other environmentally relevant polycyclic aromatic hydrocarbons (PAHs). The catalytic efficiency (k(cat)/K(m)) of mGSTA1-1 for the GSH conjugation of (+)-anti-BPDE (108/mM/s) was reduced by about 58% upon replacement of arginine 216 with alanine (R216A). This was mainly due to a significantly lower V(max) for the R216A mutant of mGSTA1-1 compared with wild-type mGSTA1-1. The R216A mutation also resulted in a statistically significant reduction (>70%) in specific activity of mGSTA1-1 toward racemic anti-diol epoxides of chrysene and benzo[c]phenanthrene (anti-CDE and anti-B[c]PDE, respectively). The catalytic activity of mGSTA2-2, which is a close structural homologue of mGSTA1-1, was also reduced upon R216A mutation. The results of the present study clearly indicate that an arginine residue at position 216 is critical for catalytic activity of mGSTA1-1 and mGSTA2-2 toward carcinogenic diol epoxide metabolites of various PAHs that are abundant in the environment and suspected human carcinogens.

[Optimization analysis of ventilation and dehumidification in manned spacecraft]

OBJECTIVE

To achieve the optimized design of system operational parameters and system components in air ventilation and dehumidification of manned spacecraft.

METHOD

Mathematical-physical model of air ventilation and dehumidification system was established. Through the design of optimal operational parameters for system performance, heat and moisture in the cabin of manned spacecraft could be removed effectively, dewing could be prevented, and the comfort demand of the astronauts could be met. Equivalent mass of the system in different operational parameters and system components was analyzed by calculation.

RESULT

The dew point temperature and the comfortability depended on the temperature and humidity of the influx, ventilation rate, and evaporation of moisture in the cabin. There were two ways to control the operational parameters of air ventilation and dehumidification system. The method based on controlling temperature didn't use recuperative heat exchangers in the loop, and the system structure for the design was simple, but it didn't meet the requirement of dissipating moisture in some conditions. The other method was based on controlling the moisture, and it could steadily keep the dew point temperature in the cabin and control the occurrence of dew. But the system structure of this design was relatively complex.

CONCLUSION

Mass and power consumption of the system could be reduced by selecting appropriate parameters and adopting the measures of optimization.

[The transcription of interleukin-8 in gastric epithelial cells by Helicobacter pylori strains in Chinese]

OBJECTIVE

To observe the effect of the vac A genotype and the existence of cag pathogenicity island (cag PAI) of Helicobacter pylori (Hp) isolated from Chinese patients on the transcription of IL-8 in gastric epithelial cells.

METHODS

The genotype of vac A and the existence of cag PAI of Hp were determined by gene sequencing and Southern blot, respectively; the constructed L5F11 cells were cocultured with the bacteria and the transcription of interleukin-8(IL-8) was indicated by luciferase activity and the cytotoxin activity showed by using HeLa cell vacuolating assay.

RESULTS

The ability to induce luciferase by the strains with complete cag PAI (n = 15) was much higher than that by the wild cag negative strain G50[(0.47 +/- 0.09) x 10(6) cpm vs (0.13 +/- 0.02) x 10(6) cpm, P < 0.01] and there was no difference in the luciferase activity induced by the strains with partial cag (n = 4) and by G50[(0.23 +/- 0.08) x 10(6) cpm vs (0.13 +/- 0.02) x 10(6) cpm, P > 0.05]; Also no difference was found in the luciferase activity induced by the strains with vac A s1/m1 (n = 5) and the strains with s1/m2 (n = 14) [(0.29 +/- 0.12) x 10(6) cpm vs (0.53 +/- 0.41) x 10(6) cpm, P > 0.05] although the formers had much higher vacuolating cytotoxin activity than the latters (P < 0.001).

CONCLUSION

The transcription of IL-8 in gastric epithelial cells induced by Hp isolated from Chinese patients was associated with the existence of cag PAI and not with the genotype of vac A.

[The clinical effect of non-penetrating trabecular surgery with reticulated sodium hyaluronate implant for treatment of primary open-angle glaucoma]

OBJECTIVE

To evaluate the clinical effect of non-penetrating trabecular surgery (NPTS) with reticulated sodium hyaluronate implant in primary open-angle glaucoma (POAG).

METHODS

NPTS with reticulated sodium hyaluronate implant was performed on 27 eyes of 25 patients with POAG. The procedure consisted of excising a deep scleral tissue including the external wall of the Schlemm's canal under a scleral flap without opening the anterior chamber, as the inner wall of the canal was left in place. Then placing a 3.0 mm x 4.5 mm x 0.5 mm or 3.5 mm x 3.5 mm x 3.5 mm reticulated sodium hyaluronate implant was placed under the flap, so that the aqueous humor may filter through the thin layer of trabeculocorneal membrane spontaneously without forming a flat chamber. The postoperative intraocular pressure (IOP), inflammation and filtering bleb were analyzed. All of patients undertook ultrasound biomicroscopy (UBM) and gonioscopy to evaluate the surgical site on the postoperative 2 weeks, 3, 6 and 9 months. The mean follow-up was (6.61 plus minus 2.47) months.

RESULTS

The IOP decreased from a mean preoperative value of (26.36 +/- 9.02) mm Hg (1 mm Hg = 0.133 kPa) to a mean postoperative value of (14.18 +/- 3.51) mm Hg (t = 6.875, P < 0.05). The number of anti-glaucomatous medications, topical or systemical, was reduced from (2.96 +/- 1.43) sorts preoperatively to (0.77 +/- 1.07) sorts postoperatively. The visual acuity remained stable (no statistical difference with chi(2) test). Six eyes had elevated IOP after operation and were controlled by eyedrops or trabecular puncture with ND: YAG laser. A slight hyphema occurred in 4 eyes with small puncture during operation. The complications such as flat chamber, inflammation and choroidal detachment were not observed. The UBM showed that the sodium hyaluronate implant degraded and a transparent liquid space existed under the scleral flap in all of patients at postoperative 3 months. The gonioscopy showed that at the surgical site the thinner and semitransparent trabecular membrane and changes of a transparent cavity could be seen in 23 eyes. In the other eyes, at the site the trabecula was translucent. The filtering blebs were formed in 8 eyes.

CONCLUSION

Non-penetrating trabecular surgery with reticulated sodium hyaluronate implant can effectively lower the IOP and reduce the sorts of anti-glaucomatous medications. The visual acuity may remain unchanged, and no serious complications commonly seen in the traditional trabeculectomy occur. The procedure is a new simple and effective one for the treatment of POAG.

The absorption edge of protein-bound mercury and a double-edge strategy for HgMAD data acquisition

The L(III) absorption edge of protein-bound mercury (Hg) has been experimentally determined using X-ray data collection from a crystal. This absorption edge is 12 291 eV, 4 eV higher than the theoretical value of elemental Hg. Considering the possible shift of the Hg absorption edge with the chemical environment in different protein crystals, a double-edge strategy for multiwavelength anomalous diffraction (MAD) data collection has been developed. The approach provides a convenient way to optimize the dispersive signal between a remote wavelength and two edge wavelengths separated from each other by 4 eV. The dispersive signals derived from both edges are used, along with anomalous signals, in MAD phasing and phase refinement. This approach has been used in the crystal structure determination of three proteins containing one Hg atom per 186-196 amino-acid residues at 2.0, 2.6 and 2.7 A resolution. A set of four wavelengths is recommended for HgMAD data acquisition: 1.0087 A (12 291 eV, edge1), 1.0084 A (12 295 eV, edge2), 1.0064 A (12 320 eV, peak) and 0.9918 A (12 500 eV, remote). Although it is no longer necessary to determine the L(III) absorption edge of protein-bound Hg experimentally, an initial fluorescence scan on the crystal for data collection is still necessary to verify the existence of Hg in the crystal.

C-terminal region amino acid substitutions contribute to catalytic differences between murine class alpha glutathione transferases mGSTA1-1 and mGSTA2-2 toward anti-diol epoxide isomers of benzo[c]phenanthrene

The molecular basis for catalytic differences between structurally closely related murine class alpha glutathione (GSH) transferases mGSTA1-1 and mGSTA2-2 in the GSH conjugation of anti-diol epoxide isomers of benzo[c]phenanthrene (anti-B[c]PDE) was investigated. GSH conjugation of both (-)- and (+)-enantiomers of anti-B[c]PDE was observed in the presence of mGSTA1-1 (60 and 40% GSH conjugation, respectively), whereas mGSTA2-2 exhibited a preference for the (-)-anti-isomer (>97%). In addition, the specific activity of mGSTA2-2 toward the (-)-anti-B[c]PDE isomer was relatively higher than that of mGSTA1-1. The amino acid sequences of mGSTA1-1 and mGSTA2-2 differ at 10 positions that are distributed in three sections. Section I contains amino acid residues in positions 65 and 95; section II contains residues in positions 157, 162, and 169, and section III contains residues in positions 207, 213, 218, 221, and 222. Enzyme activity measurements with chimeras of mGSTA1-1 and mGSTA2-2 revealed that amino acid substitutions in section III account for their differential enantioselectivity and catalytic activity toward anti-B[c]PDE. Site-directed mutagenesis of amino acid residues in section III of mGSTA2-2 with corresponding residues of mGSTA1-1 followed by activity measurements of the wild type and mutated enzymes indicates that leucine 207 and phenylalanine 221 may be critical for the high catalytic activity of mGSTA2-2 toward (-)-anti-B[c]PDE. Molecular modeling studies demonstrated that the active site of mGSTA1-1 accommodates both enantiomers of anti-B[c]PDE, whereas the (-)-anti-isomer interacts more favorably with active site residues in mGSTA2-2. The results of this study clearly indicate that amino acid substitutions in the C-terminal region contribute to catalytic differences between mGSTA1-1 and mGSTA2-2 with respect to anti-B[c]PDE.

[Effect of environmental factors on N and P uptake by Gracilaria tenuistipitata var. liui Zhang et Xia]

The effect of light intensity, pH, temperature, salinity on the uptake of nitrogen and phosphorus by Gracilaria tenuistipitata var. liui Zhang et Xia was were studied under laboratory conditions. The uptake rate of nitrogen reached as high as 0.32-0.36 mumol.g-1.h-1 at favorable light intensity of 800-2400 mumol photon.m-2.s-1, while that of phosphorus reached 0.017-0.018 mumol.g-1.h-1 at 320-1600 mumol photon.m-2.s-1. The nutrient uptake rate reached the maximum at pH 8.0. A significant difference of N uptake rate at different temperatures or salinities and that of P uptake rate at different temperatures were found. The N uptake rate was higher at 21-26 degrees C and 20@1000-28@1000, but P uptake was higher at 21-26 degrees C. There was no interaction between temperature and salinity.

The effects of thermal and hydric environments on hatching success, embryonic use of energy and hatchling traits in a colubrid snake, Elaphe carinata

We examined the effects of thermal and hydric environments on hatching success, the embryonic use of energy and hatchling traits in a colubrid snake, Elaphe carinata. The eggs were incubated at four temperatures ranging from 24 to 32 degrees C on substrates with water potentials of 0 and -220 kPa using a 4x2 factorial design. Both thermal and hydric environments affected the water exchange between eggs and their surroundings. Eggs incubated in wetter substrates gained mass throughout the course of incubation, whereas eggs in drier substrates gained mass during the first half of incubation and lost mass thereafter. Hatching success was noticeably higher at 26 and 30 degrees C than at 24 and 32 degrees C, but among treatments, differences in hatching success were not significant. Temperature significantly affected the duration of incubation and most hatchling traits examined. Deformed hatchlings were found in all temperature treatments, with more deformities observed at 32 degrees C. Hatchlings from eggs incubated at different temperatures differed in wet body mass, but the differences stemmed mainly from variation in water contents. Embryos at different temperatures completed development at nearly the same expenditure of energy and catabolized nearly the same amount of lipids, but hatchlings from different temperatures differed in the development condition of carcass at hatching. Hatchlings from eggs incubated at 26 degrees C were larger in SVL than those from other higher or lower incubation temperatures, characteristically having larger carcasses; hatchlings from 32 degrees C eggs were smaller in SVL and had smaller carcasses but larger residual yolks than those from lower incubation temperatures. Hatchlings from eggs incubated at 24 degrees C were shorter in tail length but greater in size (SVL)-specific body wet mass than those from higher incubation temperatures. Within the range from -220 to 0 kPa, the substrate water potential did not affect hatching success, the embryonic use of energy and all hatchling traits examined, and the effects of temperature were independent of the effects of substrate water potential. Therefore, our data add evidence showing that embryonic development in reptiles with pliable-shelled eggs is relatively insensitive to variation in hydric environments during incubation.

Measuring the P-odd pion-nucleon coupling h((1))(piNN) in pi(+)-photoproton production near threshold

We show that gamma-->p-->pi(+)n in the threshold region is an excellent candidate for measuring the leading parity-violating pion-nucleon coupling h((1))(piNN) to an uncertainty of 20% if it has a natural size from dimensional analysis. The conclusion is based on a large unpolarized cross section, a new low-energy theorem for the photon polarization asymmetry at the threshold A(gamma)/(th) = square root of 2 f(pi)(mu(p)-mu(n))h((1))(piNN)/g(A)m(N) approximately h((1))(piNN)/2, and its strong dominance at forward and backward angles in the threshold region.

Bisubstrate analogue inhibitors of 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase: synthesis and biochemical and crystallographic studies

6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) catalyzes the transfer of pyrophosphate from ATP to 6-hydroxymethyl-7,8-dihydropterin (HP), leading to the biosynthesis of folate cofactors. Like other enzymes in the folate pathway, HPPK is an ideal target for the development of antimicrobial agents because the enzyme is essential for microorganisms but is absent from human and animals. Three bisubstrate analogues have been synthesized for HPPK and characterized by biochemical and X-ray crystallographic analyses. All three bisubstrate analogues consist of a pterin, an adenosine moiety, and a link composed of 2-4 phosphoryl groups. P(1)-(6-Hydroxymethylpterin)-P(2)-(5'-adenosyl)diphosphate (HP(2)A, 5) shows little affinity and inhibitory activity for E. coli HPPK. P(1)-(6-Hydroxymethylpterin)-P(3)-(5'-adenosyl)triphosphate (HP(3)A, 6) shows moderate affinity and inhibitory activity with K(d) = 4.25 microM in the presence of Mg(2+) and IC(50) = 1.27 microM. P(1)-(6-Hydroxymethylpterin)-P(4)-(5'-adenosyl)tetraphosphate (HP(4)A, 7) shows the highest affinity and inhibitory activity with K(d) = 0.47 microM in the presence of Mg(2+) and IC(50) = 0.44 microM. The affinity of MgHP(4)A for HPPK is approximately 116 and 76 times higher than that of MgADP and 6-hydroxymethylpterin, respectively. The crystal structure of HPPK in complex with 7 (HPPK.MgHP(4)A) has been determined at 1.85 A resolution with a crystallographic R factor of 0.185. The crystal structure shows that 7 occupies both HP- and ATP-binding sites and induces significant conformational changes in HPPK. The biochemical and structural studies of the bisubstrate analogues indicate that the bisubstrate analogue approach can produce more potent inhibitors for HPPK and the minimum length of the link for a bisubstrate analogue is approximately 7 A.

[Gene rearrangement and p53 expression in defining the nature of angioimmunoblastic lymphadenopathy]

OBJECTIVE

To investigate gene rearrangement and p53 expression in defining the nature of angioimmunoblastic lymphadenopathy.

METHODS

DNA was extracted from paraffin-embedded tissue blocks of 44 angioimmunoblastic lymphadenopathy (AIL) patients and analyzed with polymerase chain reaction (PCR) for IgH and TCRgamma gene rearrangement. Immunohistochemistry staining was used to detect p53 protein expression. Thirty-five cases were followed-up.

RESULTS

12 out of 44 cases (27.3%) showed TCRgamma gene rearrangement and 2 (4.5%) showed IgH gene rearrangement. Rearrangement of both IgH and TCRgamma genes were detected in 2 cases (4.5%). 14 cases (31.8%) showed p53 positive expression, among which 12 showed positive rearrangement and 2 showed negative (P < 0.01). Eight out of 11 patients of positive gene rearrangement died in one year, while only 3 patients were still alive at the eighteenth month of follow-up, three of 24 patients of negative gene rearrangement were found dead at the time of the one year follow-up, while the rest 21 patients were alive and the longest survival time was 96 months.

CONCLUSIONS

Gene rearrangement can define the pathological nature of AIL. The expression of p53 is highly related to gene rearrangement, and thus an important immunological marker in research on AIL.

International Child Care Practices Study: infant sleeping environment

BACKGROUND

The International Child Care Practices Study (ICCPS) has collected descriptive data from 21 centres in 17 countries. In this report, data are presented on the infant sleeping environment with the main focus being sudden infant death syndrome (SIDS) risk factors (bedsharing and infant using a pillow) and protective factors (infant sharing a room with adult) that are not yet well established in the literature.

METHODS

Using a standardised protocol, parents of infants were surveyed at birth by interview and at 3 months of age mainly by postal questionnaire. Centres were grouped according to geographic location. Also indicated was the level of SIDS awareness in the community, i.e. whether any campaigns or messages to "reduce the risks of SIDS" were available at the time of the survey.

RESULTS

Birth interview data were available for 5488 individual families and 4656 (85%) returned questionnaires at 3 months. Rates of bedsharing varied considerably (2-88%) and it appeared to be more common in the samples with a lower awareness of SIDS, but not necessarily a high SIDS rate. Countries with higher rates of bedsharing appeared to have a greater proportion of infants bedsharing for a longer duration (>5 h). Rates of room sharing varied (58-100%) with some of the lowest rates noted in centres with a higher awareness of SIDS. Rates of pillow use ranged from 4% to 95%.

CONCLUSIONS

It is likely that methods of bedsharing differ cross-culturally, and although further details were sought on different bedsharing practices, it was not possible to build up a composite picture of "typical" bedsharing practices in these different communities. These data highlight interesting patterns in child care in these diverse populations. Although these results should not be used to imply that any particular child care practice either increases or decreases the risk of SIDS, these findings should help to inject caution into the process of developing SIDS prevention campaigns for non-Western cultures.

Crystal structure of unligated guanylate kinase from yeast reveals GMP-induced conformational changes

The crystal structure of guanylate kinase (GK) from yeast (Saccharomyces cerevisiae) with a non-acetylated N terminus has been determined in its unligated form (apo-GK) as well as in complex with GMP (GK.GMP). The structure of apo-GK was solved with multiwavelength anomalous diffraction data and refined to an R-factor of 0.164 (R(free)=0.199) at 2.3 A resolution. The structure of GK.GMP was determined using the crystal structure of GK with an acetylated N terminus as the search model and refined to an R-factor of 0.156 (R(free)=0.245) at 1.9 A. GK belongs to the family of nucleoside monophosphate (NMP) kinases and catalyzes the reversible phosphoryl transfer from ATP to GMP. Like other NMP kinases, GK consists of three dynamic domains: the CORE, LID, and NMP-binding domains. Dramatic movements of the GMP-binding domain and smaller but significant movements of the LID domain have been revealed by comparing the structures of apo-GK and GK.GMP. apo-GK has a much more open conformation than the GK.GMP complex. Systematic analysis of the domain movements using the program DynDom shows that the large movements of the GMP-binding domain involve a rotation around an effective hinge axis approximately parallel with helix 3, which connects the GMP-binding and CORE domains. The C-terminal portion of helix 3, which connects to the CORE domain, has strikingly higher temperature factors in GK.GMP than in apo-GK, indicating that these residues become more mobile upon GMP binding. The results suggest that helix 3 plays an important role in domain movement. Unlike the GMP-binding domain, which moves toward the active center of the enzyme upon GMP binding, the LID domain moves away from the active center and makes the presumed ATP-binding site more open. Therefore, the LID domain movement may facilitate the binding of MgATP. The structure of the recombinant GK.GMP complex superimposes very well with that of the native GK.GMP complex, indicating that N-terminal acetylation does not have significant impact on the three-dimensional structure of GK.

Studying hadronic structure of the photon in lattice QCD

We show that the matrix element of a local quark-gluon operator in the photon state, <gamma(klambda)/O/gamma(klambda)>, can be calculated in lattice QCD. The result is generalized to other quantities involving spacelike photons, including the transition form factor gammagamma*-->pi(0) and the virtual-photon-nucleon Compton amplitude <gamma*N /gamma*N> which can be used to define the generalized Drell-Hearn-Gerasimov and Bjorken sum rules.

Complete crystal structure of monocyte chemotactic protein-2, a CC chemokine that interacts with multiple receptors

Monocyte chemotactic protein 2 (MCP-2) is a CC chemokine that utilizes multiple cellular receptors to attract and activate human leukocytes. MCP-2 is a potent inhibitor of HIV-1 by virtue of its high-affinity binding to the receptor CCR5, one of the major coreceptors for HIV-1. Although a few structures of CC chemokines have been reported, none of these was determined with the N-terminal pyroglutamic acid residue (pGlu1) and a complete C-terminus. pGlu1 is essential for the chemotactic activity of MCP-2. Recombinant MCP-2 has Gln1 at the N terminus, 12-15% of which cyclizes automatically and forms pGlu1. The chemotactic activity of such MCP-2 mixture, which contains 12-15% pGlu1-form and 85-88% Gln1-form protein, is approximately 10 times lower when compared with that of fully cyclized MCP-2 preparation. Therefore, this chemokine is practically inactive without pGlu1. We have determined the complete crystal structure of MCP-2 that contains both pGlu1 and an intact C-terminus. With the existence of pGlu1, the conformation of the N-terminus allows two additional interactions between the two subunits of MCP-2 dimer: a hydrogen bond between pGlu1 and Asn17 and a salt bridge between Asp3 and Arg18. Consequently, both pGlu1 are anchored and buried, and thereby, both N-terminal regions are protected against protease degradation. We have also observed not previously reported extended helical nature of the C terminal region, which covers residues 58-74.

Residue R216 and catalytic efficiency of a murine class alpha glutathione S-transferase toward benzo[a]pyrene 7(R),8(S)-diol 9(S), 10(R)-epoxide

Murine class alpha glutathione S-transferase A1-1 (mGSTA1-1), unlike mammalian class alpha GSTs, is the most efficient in the glutathione (GSH) conjugation of the ultimate carcinogenic metabolite of benzo[a]pyrene, (+)-anti-7,8-dihydroxy-9,10-oxy-7,8,9, 10-tetrahydrobenzo[a]pyrene [(+)-anti-BPDE] [Hu, X., Srivastava, S. K., Xia, H., Awasthi, Y. C., and Singh, S. V. (1996) J. Biol. Chem. 271, 32684-32688]. Here, we report the crystal structures of mGSTA1-1 in complex with GSH and with the GSH conjugate of (+)-anti-BPDE (GSBpd) at 1.9 and 2.0 A resolution, respectively. Both crystals belong to monoclinic space group C2 with one dimer in the asymmetric unit. The structures reveal that, within one subunit, the GSH moiety interacts with residues Y8, R14, K44, Q53, V54, Q66, and T67, whereas the hydrophobic moiety of GSBpd interacts with the side chains of F9, R14, M207, A215, R216, F219, and I221. In addition, the GSH moiety interacts with D100 and R130 from the other subunit across the dimer interface. The structural comparison between mGSTA1-1.GSH and mGSTA1-1.GSBpd reveals significant conformational differences. The movement of helix alpha9 brings the residues on the helix into direct interaction with the product. Most noticeable are the positional displacement and conformational change of R216, one of the residues located in helix alpha9. The side chain of R216, which points away from the H-site in the mGSTA1-1.GSH complex, probes into the active site and becomes parallel with the aromatic ring system of GSBpd. Moreover, the guanidinium group of R216 shifts approximately 8 A and forms a strong hydrogen bond with the C8 hydroxyl group of GSBpd, suggesting that the electrostatic assistance provided by the guanidinium group facilitates the ring-opening reaction of (+)-anti-BPDE. The structure of mGSTA1-1. GSBpd is also compared with those of hGSTP1-1[V104,A113].GSBpd, hGSPA1-1.S-benzylglutathione, and mGSTA4-4. 4-S-glutathionyl-5-pentyltetrahydrofuran-2-ol. The comparison provides further evidence that supports the functional roles of R216 and helix alpha9. The lack of mobility of helix alpha9 and/or the lack of electrostatic assistance from R216 may be responsible for the relatively lower activity of hGSTA1-1, mGSTA4-4, and hGSTP1-1 toward (+)-anti-BPDE.

Catalytic center assembly of HPPK as revealed by the crystal structure of a ternary complex at 1.25 A resolution

BACKGROUND

Folates are essential for life. Unlike mammals, most microorganisms must synthesize folates de novo. 6-Hydroxymethyl-7, 8-dihydropterin pyrophosphokinase (HPPK) catalyzes pyrophosphoryl transfer from ATP to 6-hydroxymethyl-7,8-dihydropterin (HP), the first reaction in the folate pathway, and therefore is an ideal target for developing novel antimicrobial agents. HPPK from Escherichia coli is a 158-residue thermostable protein that provides a convenient model system for mechanistic studies. Crystal structures have been reported for HPPK without bound ligand, containing an HP analog, and complexed with an HP analog, two Mg(2+) ions, and ATP.

RESULTS

We present the 1.25 A crystal structure of HPPK in complex with HP, two Mg(2+) ions, and AMPCPP (an ATP analog that inhibits the enzymatic reaction). This structure demonstrates that the enzyme seals the active center where the reaction occurs. The comparison with unligated HPPK reveals dramatic conformational changes of three flexible loops and many sidechains. The coordination of Mg(2+) ions has been defined and the roles of 26 residues have been derived.

CONCLUSIONS

HPPK-HP-MgAMPCPP mimics most closely the natural ternary complex of HPPK and provides details of protein-substrate interactions. The coordination of the two Mg(2+) ions helps create the correct geometry for the one-step reaction of pyrophosphoryl transfer, for which we suggest an in-line single displacement mechanism with some associative character in the transition state. The rigidity of the adenine-binding pocket and hydrogen bonds are responsible for adenosine specificity. The nonconserved residues that interact with the substrate might be responsible for the species-dependent properties of an isozyme.

Interventional treatment of huge hepatic cavernous hemangioma

OBJECTIVE

To study the methods of interventional treatment of huge hepatic cavernous hemangioma (HCH).

METHOD

A total of 14 patients with HCH were treated with lipiodol-ultrafluid (10-15 ml), bleomycin A (PYM 16-32 mg), and gelatin-sponge particles.

RESULTS

DSA hepatic arteriography showed multiple vascular lakes in the early arterial phase, so-called "to hang the fruits on the branches", which persisted for a long time. CT scan showed a significant reduction in tumor size in 8 of the 14 patients after the treatment.

CONCLUSION

Embolization with lipiodol-ultrafluid, PYM and gelatin sponge particles is one of the best methods for the treatment of HCH.

Optimized separation of pharmacologically active anthraquinones in Rhubarb by capillary electrochromatography

A capillary electrochromatography (CEC) method with diode-array detection has been developed for the separation of the therapeutically important anthraquinones from Rhubarb extract and commercial traditional Chinese drugs containing Rhubarb. The separation of four major anthraquinones (aloe-emodin, emodin, chrysophanol, and physcion) was optimized with respect to pH and concentration of buffers, addition of acetonitrile, applied voltage, and column temperature. Baseline separation was achieved for the four anthraquinones in less than 12 min using a background electrolyte consisting of 5 mM acetic acid (pH 4.5) with 80% acetonitrile. The possibility of CEC for the analysis of traditional Chinese medicines was discussed.

[Morphologic analysis of 14 cases of hepatic angiomyolipoma]

OBJECTIVE

To study the morphology of hepatic angiomyolipoma (HAML).

METHODS

HE staining, PAS staining, immunohistochemistry and electronic microscopy were used to study 10 cases from our department and 4 cases from consultation.

RESULTS

All 14 HAML cases showed perivascular epithelioid cells (PEC) with 4 different types of morphology. They presented characteristic PAS positivity premelanosome like structures and dense body under electronic microscopy. Immunohistochemistry demonstrated positive reaction for both actin and HMB45.

CONCLUSION

Light and electronmicroscopic features and immunophenotype of HAML are characteristic of PEC related lesion.

Calibration and LOD/LOQ estimation of a chemiluminescent hybridization assay for residual DNA in recombinant protein drugs expressed in E. coli using a four-parameter logistic model

Calibration is the process of fitting a model based on reference data points (x, y), then using the model to estimate an unknown x based on a new measured response, y. In DNA assay, x is the concentration, and y is the measured signal volume. A four-parameter logistic model was used frequently for calibration of immunoassay when the response is optical density for enzyme-linked immunosorbent assay (ELISA) or adjusted radioactivity count for radioimmunoassay (RIA). Here, it is shown that the same model or a linearized version of the curve are equally useful for the calibration of a chemiluminescent hybridization assay for residual DNA in recombinant protein drugs and calculation of performance measures of the assay.

Cell specificity of Helicobacter pylori cytotoxin is determined by a short region in the polymorphic midregion

There are two alleles of the vacuolating cytotoxin gene from Helicobacter pylori, which code for toxins with different cell specificities. By analyzing the phenotypes of natural and artificial chimeras between the two forms of the protein, we have delimited a short stretch of amino acids which determine the cell specificity.

Methanocarba analogues of purine nucleosides as potent and selective adenosine receptor agonists

Adenosine receptor agonists have cardioprotective, cerebroprotective, and antiinflammatory properties. We report that a carbocyclic modification of the ribose moiety incorporating ring constraints is a general approach for the design of A(1) and A(3) receptor agonists having favorable pharmacodynamic properties. While simple carbocyclic substitution of adenosine agonists greatly diminishes potency, methanocarba-adenosine analogues have now defined the role of sugar puckering in stabilizing the active adenosine receptor-bound conformation and thereby have allowed identification of a favored isomer. In such analogues a fused cyclopropane moiety constrains the pseudosugar ring of the nucleoside to either a Northern (N) or Southern (S) conformation, as defined in the pseudorotational cycle. In binding assays at A(1), A(2A), and A(3) receptors, (N)-methanocarba-adenosine was of higher affinity than the (S)-analogue, particularly at the human A(3) receptor (N/S affinity ratio of 150). (N)-Methanocarba analogues of various N(6)-substituted adenosine derivatives, including cyclopentyl and 3-iodobenzyl, in which the parent compounds are potent agonists at either A(1) or A(3) receptors, respectively, were synthesized. The N(6)-cyclopentyl derivatives were A(1) receptor-selective and maintained high efficacy at recombinant human but not rat brain A(1) receptors, as indicated by stimulation of binding of [(35)S]GTP-gamma-S. The (N)-methanocarba-N(6)-(3-iodobenzyl)adenosine and its 2-chloro derivative had K(i) values of 4.1 and 2.2 nM at A(3) receptors, respectively, and were highly selective partial agonists. Partial agonism combined with high functional potency at A(3) receptors (EC(50) < 1 nM) may produce tissue selectivity. In conclusion, as for P2Y(1) receptors, at least three adenosine receptors favor the ribose (N)-conformation.

Dissecting the nucleotide binding properties of Escherichia coli 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase with fluorescent 3'(2)'-o-anthraniloyladenosine 5'-triphosphate

6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) catalyzes the transfer of pyrophosphate from ATP to 6-hydroxymethyl-7, 8-dihydropterin, the first reaction in the folate biosynthetic pathway. Like other enzymes in the folate pathway, HPPK is an ideal target for development of antimicrobial agents because the enzyme is essential for microorganisms but is absent from humans and animals. Using 3'(2')-o-anthraniloyladenosine 5'-triphosphate as a fluorescent probe, a fluorometric competitive binding assay has been developed for measuring the dissociation constants of various compounds that bind to the ATP site of HPPK. The fluorometric assay has been used to determine the nucleotide specificity and dissect the energetics of the binding of MgATP. The order of affinity of various nucleoside triphosphates for HPPK is MgATP>MgGTP>MgITP>MgXTP approximately MgUTP approximately MgCTP. The affinity of MgATP for HPPK (K(d)=2.6+/-0.06 microM) is 260-fold higher than that of MgGTP and more than 1000-fold higher than those of the other nucleoside triphosphates, indicating that HPPK is highly specific with respect to the base moiety of the nucleotide. The affinity of ATP for HPPK in the presence of Mg(2+) is 15 times that in the absence of Mg(2+), indicating that the metal ion is important for the binding of the nucleotide. Removal of the gamma-phosphate from MgATP reduces its affinity for HPPK by a factor of approximately 21. The affinity of AMP for HPPK is about one third that of ADP and almost the same as that of adenosine. The result suggests that among the three phosphoryl groups of MgATP, the gamma-phosphoryl group is most critical for binding to HPPK and the alpha-phosphoryl group contributes little to the binding of the nucleotide. The affinity of MgATP is 18 times that of MgdATP, indicating that the 2'-hydroxyl group of MgATP is also important for binding. van't Hoff analysis suggests that binding of MgATP is mainly driven by enthalpy at 25 degrees C and the entropy of binding is also in favor of the formation of the HPPK.MgATP complex.

Determination of the alkaloid content in different parts of some Mahonia plants by HPCE

The contents of three quaternary alkaloids (berberine, palmatine, jatrorrhizine) in different parts of the genus Mahonia were determined by high-performance capillary electrophoresis (HPCE). The background electrolyte system composed of 0.1 M phosphate buffer (pH 7.0)-methanol (2:1 V/V) was found to be the most suitable solution for this separation. Brucine was used as internal standard. The linear calibration ranges were 0.004986-0.4986 mg ml-1 (r = 0.9990, n = 5) for berberine, 0.005049-0.5049 mg ml-1 (r = 0.9996, n = 5) for palmatine, and 0.005058-0.5058 mg ml-1 (r = 0.9984, n = 5) for jatrorrhizine. The relative standard deviations were 1.56%, 1.02%, and 1.60% for berberine, palmatine, and jatrorrhizine (n = 6), respectively. The recoveries were determined to be 96.00-101.66% for berberine, 100.15-102.97% for palmatine, and 96.68-102.44% for jatrorrhizine. By using proposed HPCE method, three alkaloids were well-separated within only 5.0 min.

[Study on the relationship between CD44v6, p53 gene mutation and ovarian carcinoma metastasis]

OBJECTIVE

To explore the relationship between CD44v6 expression, p53 gene mutation, cell ploidy and ovarian metastasis.

METHODS

Eighty-five ovarian specimens (20 normal specimens, 20 benign tumors, 20 non-metastatic carcinomas and 25 metastatic carcinomas) were collected. Cell ploidy and the distribution of cell population in each stage of cell cycle were detected by flow cytometry. By using techniques such as reverse transcription-polymerase chain reaction, southern blot and image analysis, the quantitative and qualitative expression of CD44v6 were determined; the mutation of p53 gene in the ovarian specimens was also determined by polymerase chain reaction-single strand conformation polymorphism with silver staining.

RESULTS

In the normal ovarian specimens, benign tumors, non-metastatic and metastatic carcinomas, the positive rates of CD44v6 expression and p53 gene mutation were 0%, 10%, 75%, 88% and 0%, 5%, 40%, 60%, respectively, both increased gradually. The mean dark density in the non-metastatic (3,820 +/- 289) and metastatic (10,132 +/- 1,521) groups was significantly different (P < 0.01). In the positive and negative CD44v6 ovarian carcinoma groups, the mean carcinoma cell percentage at the G2M stage was 5.90% and 5.06% (P > 0.05), mean aneuploidy carcinoma cell percentage was 57% and 50% (P > 0.05) respectively. In the mutated and non-mutated p53 gene groups, their mean cell population at the G2M stage was 11.15% and 5.85% (P < 0.05), mean aneuploidy carcinoma cell percentage was 74% and 36% (P < 0.05), respectively.

CONCLUSIONS

The expression of CD44v6 is closely related to carcinoma metastasis. The relationship between CD44v6 expression, p53 gene mutation and carcinoma metastasis can be involved in the different mechanism. As compared to mutated p53 gene, CD44v6 appears to be more suitable as a metastatic marker.

Influence of incubation temperature on morphology, locomotor performance, and early growth of hatchling wall lizards (Podarcis muralis)

Eggs of wall lizards (Podarcis muralis) were incubated at three temperatures approaching the upper limit of viability for embryonic development in this species (26, 29, and 32 degrees C) to assess the influence of temperature on various aspects of hatchling phenotype likely affecting fitness. The thermal environment affected size and several morphometric characteristics of hatchling lizards. Hatchlings from eggs incubated at 32 degrees C were smaller (snout-vent length, SVL) than those from 26 and 29 degrees C and had smaller mass residuals (from the regression on SVL) as well as shorter tail, head, and femur relative to SVL. Variation in the level of fluctuating asymmetry in meristic and morphometric traits associated with incubation temperatures was quite high but not clearly consistent with the prediction that environmental stress associated with the highest incubation temperatures might produce the highest level of asymmetry. When tested for locomotor capacity in trials developed at body temperatures of 32 and 35 degrees C, hatchlings from the 32 degrees C incubation treatment exhibited the worst performance in any aspect considered (burst speed, maximal length, and number of stops in the complete run). Repeated measures ANCOVAs (with initial egg mass as covariate) of snout-vent length and mass of lizards at days 0 and 20 revealed significant effects of incubation temperature only for mass, being again the hatchlings from eggs incubated at 32 degrees C those exhibiting the smallest final size. All together, our results evidenced a pervasive effect of thermal regime during incubation (and hence of nest site selection) on hatchling phenotypes. However, incubation temperature does not affect hatchling phenotypes in a continuous way; for most of the analysed traits a critical threshold seems to exist between 29 and 32 degrees C, so that hatchlings incubated at 32 degrees C exhibited major detrimental effects. J. Exp. Zool. 286:422-433, 2000.

[Rotational analysis of fluorescence excitation spectrum of NO2 in the range of 589.3-594.0 nm]

This paper shows the measurement of high-resolution fluorescence excitation spectrum of uncooled NO2 in the range of 589.3-594 nm. The 11 vibronic bands approximately 120 lines in this region were rotationally assigned. The analysis shows that these lines are mainly arise from the parallel transition of 2B2(K' = 0)-->2A2(K" = 0). The spectroscopic parameters describing these bands are obtained. The discussion is given to the complexity of spectrum structure.

Smad1 domains interacting with Hoxc-8 induce osteoblast differentiation

Bone morphogenetic proteins are potent osteotropic agents that induce osteoblast differentiation and bone formation. The signal transduction of bone morphogenetic proteins has recently been discovered to involve Smad proteins. Smad1 is an essential intracellular component that is specifically phosphorylated by bone morphogenetic protein receptors and translocated into the nucleus upon ligand stimulation. Previously, we have reported that Smad1 activates osteopontin gene expression in response to bone morphogenetic protein simulation through an interaction with a homeodomain transcription factor, Hoxc-8. In the present study, the interaction domains between the two proteins were characterized by deletional analysis in both yeast two-hybrid and gel shift assays. Two regions within the amino-terminal 87 amino acid residues of Smad1 were mapped to interact with Hoxc-8, one of which binds to the homeodomain. Overexpression of recombinant cDNAs encoding the Hoxc-8 interaction domains of Smad1 effectively activated osteopontin gene transcription in transient transfection assays. Furthermore, stable expression of these Smad1 fragments in 2T3 osteoblast precursor cells stimulated osteoblast differentiation-related gene expression and led to mineralized bone matrix formation. Our data suggest that the interaction of amino-terminal Smad1 with Hoxc-8 mimics bone morphogenetic protein signaling and is sufficient to induce osteoblast differentiation and bone cell formation.

Patterns of gene expression associated with BMP-2-induced osteoblast and adipocyte differentiation of mesenchymal progenitor cell 3T3-F442A

The pluripotent mesenchymal stem cells give rise to osteoblasts, adipocytes, chondrocytes, and myoblasts. The differentiation of these stem cells into each of the mature functional cells may be controlled by a distinctive master gene(s) and is associated with temporal and spatial expression of diverse genes. Identification of genes that are expressed during the differentiation of the mesenchymal cells to osteoblasts is, therefore, important to obtain insights into the molecular mechanisms of osteogenesis. The murine undifferentiated mesenchymal cell 3T3-F442A, when treated with the bone morphogenetic protein 2 (BMP-2), a well-characterized inducer of mesenchymal cell differentiation, exhibited both osteoblastic and adipocytic differentiation. Using the SAGE (serial analysis of gene expression) technique, which has been shown to enable quantitative analysis of large numbers of genes in a simple and quick manner, we obtained 1600 sequence tags representing 2107 individual nucleotide sequences from control and BMP-2-treated 3T3-F442A cells, respectively. By comparing the frequency of tag occurrence, we found profiles of up- or downregulated genes associated with osteoblast or adipocyte phenotype such as type I collagen, osteonectin and OSF-2, or C/EBPbeta, aP2, fatty acid synthase, and lipoprotein lipase, respectively, in BMP-2-treated 3T3-F442A cells. Our data show that BMP-2 induces not only osteoblastic but also adipocytic differentiation in the 3T3-F442A cells. They also show that the 3T3-F442A cells have bipotentials of differentiating toward osteoblasts and adipocytes. The results, therefore, might explain the inverse correlation between trabecular bone volume and fat volume in the bone marrow cavity. The results also suggest that the SAGE may be a useful technique that allows us a fast and efficient way to generate global and local views of gene expression associated with cellular differentiation of the mesenchymal stem cells.

Extinction of E-cadherin expression in breast cancer via a dominant repression pathway acting on proximal promoter elements

Inactivation of the E-cadherin cell adhesion molecule is believed critical in the development and behavior of many epithelial cancers, though mutations in the E-cadherin gene account for inactivation in only a fraction of cases. In many breast cancer lines, E-cadherin transcription is extinguished, but the role and significance of alterations in trans-acting transcription factors, promoter hypermethylation, and chromatin changes remain unresolved. To gain further insights into mechanisms underlying E-cadherin inactivation in breast cancer, we analysed somatic cell hybrids resulting from pairwise fusions between breast cancer lines with intact E-cadherin transcription (E-cad+) and lines lacking E-cadherin transcription (E-cad-). All hybrid lines failed to express E-cadherin transcripts and protein, despite the fact that E-cadherin alleles from E-cad+ lines were present in the hybrids. Elements in the proximal 108 bp of the E-cadherin promoter, when present in reporter gene constructs, were sufficient to direct strong transcription in E-cad+ breast lines, but displayed weak activity in E-cad- parental lines and hybrids. E-cadherin expression could not be restored in E-cad- lines or hybrids by treatment with a DNA demethylating agent and/or a histone deacetylase inhibitor. Our findings suggest loss of E-cadherin expression in some breast cancers may be due to dominant repression of the trans-acting pathways that regulate E-cadherin transcription.

[A preliminary report of a new technique: non-penetrating trabecular surgery]

OBJECTIVE

To evaluate the clinical effect of nonpenetrating trabecular surgery with sodium hyaluronate gel implant in Primary Open-Angle Glaucoma(POAG).

METHODS

Twenty-four eyes of 22 patients with medically uncontrolled POAG were underwent nonpenetrating trabecular surgery with hyaluronate gel implant. The procedure was performed involing excising a deep-sclera tissue that flush with innerwall of Schlemm' s canal without opening the anterior chamber, then placing a 3 mm x 4.5 mm x 0.5 mm or 3.5 mm x 3.5 mm x 3.5 mm sodium hyaluronate gel implant under the scleral flap respectively. The postoperative Intraocular Pressure (IOP), Inflammation and fitering bleb were analysised. All of patients were undertaken ultrasound biomicroscopy (UBM) to evaluate the surgery site on postoperative 1-3 months. Mean follow-up was 3.9 +/- 2.2 months.

RESULTS

The IOP decreased from a mean preoperative value of 24.4 +/- 9.1 mmHg to a mean postoperative value of 15.1 +/- 3.7 mmHg (P < 0.01). The number of anti-glaucomatous medications by topically or systemically was reduced from preoperative sorts of 2.8 +/- 1.4 to postoperative sorts of 0.7 +/- 1.0 (P < 0.01). The visual acuity remained stable, 6 eyes had IOP elevated and 2 eyes had occured hyphema. The complications such as flat chamber, inflammation and detachment of choroid were not observed. The UBM showed that the hyaluronate gel implant wasn't degraded and a transparent liquid space was formed under the scleral flap in all of patients on postoperatively 1-3 month. The filtering blebs were formed in some patients.

CONCLUSION

Nonpenetrating trabecular surgery with hyaluronate gel implant can effectively lower IOP and reduce the number of anti-glaucomatous medications. No severe complications occured. With a simple postoperative nursing, it can be performed in clinic. It is proved to be a promising and new special technique to treat glaucoma.

[Clinic and immunophenotypic studies on midline malignant histiocytosis]

OBJECTIVE

To understand the clinic opatholgic changes of midline malignant histiocytosis (MMH), and to explain the source of atypical lymphoid cells (ALC) of MMH, so as to search after the relation between MMH and malignant lymphoma.

METHOD

Histopathologic section of 39 cases of MMH were taken HE staining and the histopathologic changes were obsered under microscope. The immunohistochemical staining was also used to examine the immunophenotype of ALC.

RESULT

1. Pathologic changes of MMH: coaglation necrosis and mixed inflammatory cells infiltration, with epithelial infiltration which distributed around the center of blood vessel were their characteristics. 2. Immunohistochemical staining result: 28 in 39 cases of MMH (71.8%) expressed the immunophenvtype of T-cell; among them 13 (33.3%) were finded both positive reaction to CD3 and CD57 antigens with ALCs at the same time.

CONCLUSION

According to immunophenotypic studies, most ALCs came from proliferation and infiltration of atypical T cell. ALCs of MMH expressed not only T-cell markers (CD3), but also NK-associated antigen (CD57). MMH was a mucosa related peripheral T/NK cell lymphoma originally.

[The genotype of vac A gene of Helicobacter pylori (Hp) and its correlation with the gastroduodenal diseases associated with Hp]

OBJECTIVE

To analyze the expression of vac A gene of Helicobacter pylori (Hp) isolated from Chinese patients and to find out the relationship between the genotype of Hp vac A and the gastroduodenal diseases associated with Hp.

METHODS

Clones of Hp obtained from patients with gastroduodenal diseases were cultured and mRNA extraction was performed with reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

92% of the strains isolated in Shanghai (China) was found to be s1/m2. Strains expressing s1/m1 forms were obtained in 4 cases. s2 form was not found.

CONCLUSION

The overwhelming majority of strains isolated from Shanghai patients expresses s1/m2 from. The s1/m2 genotype is dispersed in all of the gastroduodenal diseases associated with Hp.

Crystal structure of a murine glutathione S-transferase in complex with a glutathione conjugate of 4-hydroxynon-2-enal in one subunit and glutathione in the other: evidence of signaling across the dimer interface

mGSTA4-4, a murine glutathione S-transferase (GST) exhibiting high activity in conjugating the lipid peroxidation product 4-hydroxynon-2-enal (4-HNE) with glutathione (GSH), was crystallized in complex with the GSH conjugate of 4-HNE (GS-Hna). The structure has been solved at 2.6 A resolution, which reveals that the active site of one subunit of the dimeric enzyme binds GS-Hna, whereas the other binds GSH. A marked asymmetry between the two subunits is evident. Most noticeable are the differences in the conformation of arginine residues 69 and 15. In all GST structures published previously, the guanidino groups of R69 residues from both subunits stack at the dimer interface and are related by a (pseudo-) 2-fold axis. In the present structure of mGSTA4-4, however, the two R69 side chains point in opposite directions, although their guanidino groups remain in contact. In the subunit with bound GSH, R69 also interacts with R15, and the guanidino group of R15 points away from the active site, whereas in the subunit that binds GS-Hna, R15 pivots into the active site, which breaks its interaction with R69. According to our previous results [Nanduri et al. (1997) Arch. Biochem. Biophys. 335, 305-310], the availability of R15 in the active site assists the conjugation of 4-HNE with GSH. We propose a model for the catalytic mechanism of mGSTA4-4 in conjugating 4-HNE with GSH-i.e., the guanidino group of R15 is available in the active site of only one subunit at any given time and the stacked pair of R69 residues act as a switch that couples the concerted movement of the two R15 side chains. The alternate occupancy of 4-HNE in the two subunits has been confirmed by our kinetic analysis that shows the negative cooperativity of mGSTA4-4 for 4-HNE. Disruption of the signaling between the subunits by mutating the R69 residues released the negative cooperativity with 4-HNE.

Analysis of flavonoids in Semen Cuscutae by micellar electrokinetic chromatography and high-performance liquid chromatography

Five different flavonoids in Semen Cuscutae were determined for the first time by micellar electrokinetic chromatography (MEKC) and reversed-phase high-performance liquid chromatography (RP-HPLC). MEKC was carried out on a 68.5-cm fused-silica capillary using 0.035 mol/L sodium dodecyl sulfate and 0.02 mol/L borate-phosphate (pH 7.0) containing 10% methanol as the running buffer. RP-HPLC was performed on a 12.5-cm Hypersil C18 (Agilent Technologies, Palo Alto, CA, U.S.A.) column with a 0.025-mol/L phosphate acid (A) - methanol (B) solvent gradient. Both MEKC and HPLC are rapid, simple, and efficient. The results obtained using these techniques are compared. MEKC and HPLC can be complementary to each other for the quality control of Semen Cuscutae.

Structure and function of residue 104 and water molecules in the xenobiotic substrate-binding site in human glutathione S-transferase P1-1

Two variants of human class pi glutathione (GSH) S-transferase 1-1 with either isoleucine or valine in position 104 (hGSTP1-1[I104] and hGSTP1-1[V104]) have distinct activity toward (+)-anti-7, 8-dihydroxy-9,10-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene [(+)-anti-BPDE]. To elucidate their structure-function relationship, we determined the crystal structures of the two variants in complex with GSBpd, the GSH conjugate of (+)-anti-BPDE, at 2.1 and 2.0 A resolution, respectively. The crystal structures reveal that residue 104 in the xenobiotic substrate-binding site (H-site) dictates the binding modes of the product molecule GSBpd with the following three consequences. First, the distance between the hydroxyl group of Y7 and the sulfur atom of GSBpd is 5.9 A in the hGSTP1-1[I104].GSBpd complex versus 3.2 A in the V104 variant. Second, one of the hydroxyl groups of GSBpd forms a direct hydrogen bond with R13 in hGSTP1-1[V104].GSBpd; in contrast, this hydrogen bond is not observed in the I104 complex. Third, in the hydrophilic portion of the H-site of the I104 complex, five H-site water molecules [Ji, X., et al. (1997) Biochemistry 36, 9690-9702] are observed, whereas in the V104 complex, two of the five have been displaced by the Bpd moiety of GSBpd. Although there is no direct hydrogen bond between Y108 (OH) and the hydroxyl groups of GSBpd, indirect hydrogen bonds mediated by water molecules are observed in both complexes, supporting the previously suggested role of the hydroxyl group of Y108 as an electrophilic participant in the addition of GSH to epoxides.

Amino acid substitutions at positions 207 and 221 contribute to catalytic differences between murine glutathione S-transferase Al-1 and A2-2 toward (+)-anti-7,8-dihydroxy-9,10-epoxy-7,8,9, 10-tetrahydrobenzo[a]pyrene

We have previously identified a novel Alpha class murine glutathione (GSH) S-transferase isoenzyme (designated mGSTAl-2) which is exceptionally efficient in catalyzing the GSH conjugation of (+)-anti-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene [(+)-anti-BPDE], the ultimate carcinogen of widespread environmental pollutant benzo[a]pyrene. Furthermore, we have demonstrated that the Al-type subunit of this isoenzyme is significantly more active toward (+)-anti-BPDE than the other subunit (mGSTA2). To establish the basis for catalytic differences between mGSTAl and mGSTA2, which differ in their primary structures by 10 amino acids [distributed in three sections (I-III) as clusters of two (residues 65 and 95), three (residues 157, 162, and 169), and five (residues 207, 213, 218, 221, and 222) amino acids], three chimeric enzymes were expressed and tested for their activity toward (+)-anti-BPDE. These studies revealed that amino acid substitution(s) in section III determined the high catalytic activity of mGSTAl. Molecular modeling studies suggested that amino acid substitutions at positions 207 and/or 221, but not at positions 213, 218, and 222, may be responsible for such a difference. To test this possibility, amino acids at positions 207 and 221 of mGSTAl were mutated with the equivalent residues of mGSTA2. Kinetic analysis of the wild type and the mutant enzymes revealed that both methionine-207 and isoleucine-221 are critical for higher activity of mGSTA1-1 toward (+)-anti-BPDE compared with that of mGSTA2-2.

Crystal structure of ERA: a GTPase-dependent cell cycle regulator containing an RNA binding motif

ERA forms a unique family of GTPase. It is widely conserved and essential in bacteria. ERA functions in cell cycle control by coupling cell division with growth rate. ERA homologues also are found in eukaryotes. Here we report the crystal structure of ERA from Escherichia coli. The structure has been determined at 2.4-A resolution. It reveals a two-domain arrangement of the molecule: an N-terminal domain that resembles p21 Ras and a C-terminal domain that is unique. Structure-based topological search of the C domain fails to reveal any meaningful match, although sequence analysis suggests that it contains a KH domain. KH domains are RNA binding motifs that usually occur in tandem repeats and exhibit low sequence similarity except for the well-conserved segment VIGxxGxxIK. We have identified a betaalphaalphabeta fold that contains the VIGxxGxxIK sequence and is shared by the C domain of ERA and the KH domain. We propose that this betaalphaalphabeta fold is the RNA binding motif, the minimum structural requirement for RNA binding. ERA dimerizes in crystal. The dimer formation involves a significantly distorted switch II region, which may shed light on how ERA protein regulates downstream events.

3D imaging of the 58 kDa cell binding subunit of the Helicobacter pylori cytotoxin

Pathogenic strains of Helicobacter pylori produce a potent exotoxin, VacA, which intoxicates gastric epithelial cells and leads to peptic ulcer. The toxin is released from the bacteria as a high molecular mass homo-oligomer of a 95 kDa polypeptide which undergoes specific proteolytic cleavage to 37 kDa and 58 kDa subunits. We have engineered a strain of H. pylori to delete the gene sequence coding for the 37 kDa subunit. The remaining 58 kDa subunit is expressed efficiently and exported as a soluble dimer that is non-toxic but binds target cells in a manner similar to the holotoxin. A 3D reconstruction of the molecule from electron micrographs of quick-freeze, deep-etched preparations reveals the contribution of each building block to the structure and permits the reconstruction of the oligomeric holotoxin starting from individual subunits. In this model P58 subunits are assembled in a ring structure with P37 subunits laying on the top. The data indicate that the 58 kDa subunit is capable of folding autonomously into a discrete structure recognizable within the holotoxin and containing the cell binding domain.

[Establishment of A + G ligation mediated polymerase chain reaction and its application in in vivo footprinting study]

OBJECTIVE

To establish a new ligation mediated PCR method for the work in in vivo footprinting study of some regions of low G-residue content or some regions of G-residue free.

METHODS

The A > G chemical cleavage method of Maxam-Gilbert sequencing was modified for ligation mediated PCR after A + G chemical cleavage and separate the PCR products by sequencing PAGE.

RESULTS

A new A + G ligation mediated method was established and could be used in vivo footprinting study.

CONCLUSIONS

Our results indicated that the newly developed method could analyze the DNA-Protein interaction at both A-residue and G-residue, enabled us to get more information and enlarged the scope of its application.

Beta- and gamma-catenin mutations, but not E-cadherin inactivation, underlie T-cell factor/lymphoid enhancer factor transcriptional deregulation in gastric and pancreatic cancer

Adenomatous polyposis coli (APC) mutations are present in >70% of colon cancers. The APC protein binds to beta-catenin (beta-cat), a protein first identified because of its role in E-cadherin (E-cad) cell adhesion. In some colon cancers lacking APC defects, mutations in presumptive glycogen synthase kinase 3beta phosphorylation sites near the beta-cat NH2 terminus appear to render beta-cat resistant to regulation by APC and glycogen synthase kinase 3beta. In cells with APC or beta-cat defects, beta-cat is stabilized and, in turn, binds to and activates T-cell factor (Tcf)/lymphoid enhancer factor (Lef) transcription factors. To further explore the role of APC, beta-cat, Tcf, and E-cad defects in gastrointestinal cancers, we assessed gastric and pancreatic cancers for constitutive Tcf transcriptional activity (CTTA). Two of four gastric and two of eight pancreatic cancer lines showed CTTA. One gastric and one pancreatic cancer had mutations in the NH2-terminal phosphorylation sites of beta-cat. The other gastric cancer with CTTA had a missense mutation at serine 28 of gamma-cat, a potential phosphorylation site in this beta-cat-related protein. Although E-cad is an important binding partner for beta-cat and gamma-cat, E-cad inactivation did not result in CTTA. The beta-cat and gamma-cat mutant proteins identified in our studies strongly activated Tcf transcription in vitro, whereas beta-cat mutant proteins with large NH2-terminal deletions had only modest effects on Tcf. Our results suggest a role for Tcf deregulation in gastric and pancreatic cancer, resulting from beta-cat and gamma-cat mutations in some cases and, in others, from yet to be defined defects. Furthermore, these data imply that the consequences of APC and beta-cat mutations are distinct from the effects of E-cad inactivation.

Crystal structure of 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase, a potential target for the development of novel antimicrobial agents

BACKGROUND

Folate cofactors are essential for life. Mammals derive folates from their diet, whereas most microorganisms must synthesize folates de novo. Enzymes of the folate pathway therefore provide ideal targets for the development of antimicrobial agents. 6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) catalyzes the transfer of pyrophosphate from ATP to 6-hydroxymethyl-7,8-dihydropterin (HP), the first reaction in the folate biosynthetic pathway.

RESULTS

The crystal structure of HPPK from Escherichia coli has been determined at 1.5 A resolution with a crystallographic R factor of 0.182. The HPPK molecule has a novel three-layered alpha beta alpha fold that creates a valley approximately 26 A long, 10 A wide and 10 A deep. The active center of HPPK is located in the valley and the substrate-binding sites have been identified with the aid of NMR spectroscopy. The HP-binding site is located at one end of the valley, near Asn55, and is sandwiched between two aromatic sidechains. The ATP-binding site is located at the other end of the valley. The adenine base of ATP is positioned near Leu111 and the ribose and the triphosphate extend across and reach the vicinity of HP.

CONCLUSIONS

The HPPK structure provides a framework to elucidate structure/function relationships of the enzyme and to analyze mechanisms of pyrophosphoryl transfer. Furthermore, this work may prove useful in the structure-based design of new antimicrobial agents.