Influence of permeating ions on Kv1.5 channel block by nifedipine

Nifedipine can block K(+) currents through Kv1.5 channels in an open-channel manner (32). Replacement of internal and external K(+) with equimolar Rb(+) or Cs(+) reduced the potency of nifedipine block of Kv1.5 from an IC(50) of 7.3 microM (K(+)) to 16.0 microM (Rb(+)) and 26.9 microM (Cs(+)). The voltage dependence of block was unaffected, and a single binding site block model was used to describe block for all three ions. By varying ion species at the intra- and extracellular mouth of the channel and by using a nonconducting W472F-Kv1.5 mutant, we demonstrated that block was conditioned by the ion permeating the pore and, to a lesser extent, by the extracellular ion species alone. In Kv1.5, the outer pore mutations R487V and R487Y reduced nifedipine potency close to that of Kv4.2 and other Kv channels with an equivalent valine. Although changing this residue can affect C-type inactivation of Kv channels, the normalized reduction and time course of currents blocked by nifedipine in 5, 135, and 300 mM extracellular K(+) concentration was the same. Similarly, a mean recovery time constant from nifedipine block of 316 ms was unchanged (332 ms) after 5-s prepulses to allow C-type inactivation. This is consistent with the conclusion that nifedipine block and C-type inactivation in the Kv1.5 channel can coexist but are mediated by distinct mechanisms coordinated by outer pore conformation.

Intensity modulated proton therapy: a clinical example

In this paper, we report on the clinical application of fully automated three-dimensional intensity modulated proton therapy, as applied to a 34-year-old patient presenting with a thoracic chordoma. Due to the anatomically challenging position of the lesion, a three-field technique was adopted in which fields incident through the lungs and heart, as well as beams directed directly at the spinal cord, could be avoided. A homogeneous target dose and sparing of the spinal cord was achieved through field patching and computer optimization of the 3D fluence of each field. Sensitivity of the resultant plan to delivery and calculational errors was determined through both the assessment of the potential effects of range and patient setup errors, and by the application of Monte Carlo dose calculation methods. Ionization chamber profile measurements and 2D dosimetry using a scintillator/CCD camera arrangement were performed to verify the calculated fields in water. Modeling of a 10% overshoot of proton range showed that the maximum dose to the spinal cord remained unchanged, but setup error analysis showed that dose homogeneity in the target volume could be sensitive to offsets in the AP direction. No significant difference between the MC and analytic dose calculations was found and the measured dosimetry for all fields was accurate to 3% for all measured points. Over the course of the treatment, a setup accuracy of +/-4 mm (2 s.d.) could be achieved, with a mean offset in the AP direction of 0.1 mm. Inhalation/exhalation CT scans indicated that organ motion in the region of the target volume was negligible. We conclude that 3D IMPT plans can be applied clinically and safely without modification to our existing delivery system. However, analysis of the calculated intensity matrices should be performed to assess the practicality, or otherwise, of the plan.

A zebrafish forebrain-specific zinc finger gene can induce ectopic dlx2 and dlx6 expression

Identification of the earliest forebrain-specific markers should facilitate the elucidation of molecular events underlying vertebrate forebrain determination and specification. Here we report the sequence and characterization of fez (forebrain embryonic zinc finger), a gene that is specifically expressed in the embryonic forebrain of zebrafish. Fez encodes a putative nuclear zinc finger protein that is highly conserved in Drosophila, zebrafish, Xenopus, mouse, and human. In zebrafish, the expression of fez becomes detectable at the anterior edge of the presumptive neuroectoderm by 70% epiboly. During the segmentation period, its expression is completely restricted to the rostral region of the prospective forebrain. At approximately 24 h postfertilization, fez expression is mostly confined to the telencephalon and the anterior-ventral region of the diencephalon. Although fez expression is present in one-eyed pinhead (oep) and cyclops (cyc) zebrafish mutants, the pattern is altered. Forced expression of fez induces ectopic expression of dlx2 and dlx6, two genes involved in brain development. Knockdown of fez function using a morpholino-based antisense oligo inhibited dlx2 expression in the ventral forebrain. Our studies indicate that fez is one of the earliest markers specific for the anterior neuroectoderm and it may play a role in forebrain development by regulating Dlx gene expression.

[Study of sesquiterpene alkaloids from Tripterygium wilfordii Hook.f]

AIM

To study the chemical composition of Tripterygium wilfordii Hook.f.

METHODS

Column chromatography was used to separate the chemical constituents. UV, IR, MS, HRMS, 1HNMR, 13CNMR (COM and OFR), 1H-1H COSY, 1H-13C COSY, 2D-NOESY and 1H-13C COLOC were used to determine the structures of the isolated constituents.

RESULTS

Two sesquiterpene alkaloids were isolated and their structures were elucidated as euonine and wilfordconine on the basis of spectral evidence.

CONCLUSION

Wilfordconine, a new sesquiterpene alkaloid, was shown to be immunosuppressive.

Use of high-frequency ultrasound imaging to improve delineation of anterior uveal melanoma for proton irradiation

The aim of this study was to evaluate high-frequency ultrasound imaging (HFUI) as an aid in localizing anterior margins of tumours of the eye for proton therapy. Proton irradiation of ocular melanoma requires an accurate assessment of all tumour margins. The tumour is marked surgically by suturing to the sclera four or five tantalum rings on the borders of the tumour defined by transillumination. In order to evaluate the clinical usefulness of high-frequency ultrasound imaging, four and five rings were surgically placed in a patient with an iris/ciliary body melanoma and in a patient with ciliochoroidal melanoma using transillumination to localize the tumour margins. Subsequently margins were verified by HFUI. In the first patient, the distances between the rings and the limbus were measured using calipers during surgery and were compared with HFUI measurements and measurements from planning software. The distances were comparable within 0.5 mm. In the second patient the treatment was planned in two different ways using EYEPLAN software. In the first scenario the shape of the tumour and its relation to the rings were obtained from the surgeon's mapping, the fundus drawing using a transilluminating point light source, and the HFUI. In the second scenario, the shape of the tumour was deduced from the ring positions only. It was observed that the maximum difference between the tumour edge as seen on high-frequency ultrasound images and the rings was 2.6 mm. The tumour volume was underestimated by 39% when tumour shape was obtained from ring positions only. During the past year we have utilized HFUI in 18 patients having tumours involving the anterior segment of the eye, among which four were treated with proton therapy. In conclusion, we believe that high-frequency ultrasound imaging provides additional information with respect to the location of tumour margins in ciliary body and anterior uveal melanoma. Occult extension of the tumour within the ciliary body or posterior iris may not be appreciated by transillumination alone.

Statistical optimization of gastric floating system for oral controlled delivery of calcium

The development of an optimized gastric floating drug delivery system is described. Statistical experimental design and data analysis using response surface methodology is also illustrated. A central, composite Box-Wilson design for the controlled release of calcium was used with 3 formulation variables: X1 (hydroxypropyl methylcellulose [HPMC] loading), X2 (citric acid loading), and X3 (magnesium stearate loading). Twenty formulations were prepared, and dissolution studies and floating kinetics were performed on these formulations. The dissolution data obtained were then fitted to the Power Law, and floating profiles were analyzed. Diffusion exponents obtained by Power Law were used as targeted response variables, and the constraints were placed on other response variables. All 3 formulation variables were found to be significant for the release properties (P <.05), while only HPMC loading was found to be significant for floating properties. Optimization of the formulations was achieved by applying the constrained optimization. The optimized formulation delivered calcium at the release rate of 40 mg/hr, with predicted n and T50% values at 0.93 and 3.29 hours, respectively. Experimentally, calcium was observed to release from the optimized formulation with n and T50% values of 0.89 (+/- 0.10) and 3.20 (+/- 0.21) hours, which showed an excellent agreement. The quadratic mathematical model developed could be used to further predict formulations with desirable release and floating properties.

Ca2+-induced phosphoethanolamine transfer to the outer 3-deoxy-D-manno-octulosonic acid moiety of Escherichia coli lipopolysaccharide. A novel membrane enzyme dependent upon phosphatidylethanolamine

Certain strains of Escherichia coli and Salmonella contain lipopolysaccharide (LPS) modified with a phosphoethanolamine (pEtN) group at position 7 of the outer 3-deoxy-d-manno-octulosonic acid (Kdo) residue. Using the heptose-deficient E. coli mutant WBB06 (Brabetz, W., Muller-Loennies, S., Holst, O., and Brade, H. (1997) Eur. J. Biochem. 247, 716-724), we now demonstrate that the critical parameter determining the presence or absence of pEtN is the concentration of CaCl(2) in the medium. As judged by mass spectrometry, half the LPS in WBB06, grown on nutrient broth with 5 mm CaCl(2), is derivatized with a pEtN group, whereas LPS from WBB06 grown without supplemental CaCl(2) is not. Membranes from E. coli WBB06 or wild-type W3110 grown on 5-50 mm CaCl(2) contain a novel pEtN transferase that uses the precursor Kdo(2)-[4'-(32)P]lipid IV(A) as an acceptor. Transferase is not present in membranes of E. coli grown with 5 mm MgCl(2), BaCl(2), or ZnCl(2). Hydrolysis of the in vitro reaction product, pEtN-Kdo(2)-[4'-(32)P]lipid IV(A), at pH 4.5 shows that the pEtN substituent is located on the outer Kdo moiety. Membranes from an E. coli pss knockout mutant grown on 50 mm CaCl(2), which lack phosphatidylethanolamine, do not contain measurable transferase activity unless exogenous phosphatidylethanolamine is added back to the assay system. The induction of the pEtN transferase by 5-50 mm CaCl(2) suggests possible role(s) in establishing transformation competence or resisting environmental stress, and represents the first example of a regulated covalent modification of the inner core of E. coli LPS.

Genetic crossover interference in the human genome

Positive crossover interference refers to the phenomenon that the occurrence of a crossover reduces the probability of another crossover in its vicinity. There have been studies reporting the presence of positive interference in humans. Some studies have also found evidence suggesting within and between chromosomal interference heterogeneity on some of the chromosomes. However, there has been no systematic study of interference and interference heterogeneity in the whole human genome, using pedigree data without first inferring crossovers. In this paper, we studied the Chi-square interference model and other models extensively to compare the relative performance of each of these models for accounting for interference and measuring strength of interference. Our results showed that the Chi-square model consistently fitted the data well and provided easily interpretable estimates of interference strength. The Chi-square model was then used to study interference and interference heterogeneity within and between chromosomes. We found strong evidence of positive interference in the whole human genome. Our results also indicated that the level of interference was fairly constant in most parts of the genome, but there was some evidence suggesting that the levels of interference for two of the chromosomes were different from the rest. We also found evidence of within chromosomal interference heterogeneity for several of the chromosomes.

The swelling behavior and wet morphology of water-absorbable polymer materials

In this research work, a low-temperature examination method for scanning electron microscopy (SEM) is introduced. A water-absorbable polymer material, the sulfonated polyethylene (SPE) ion-exchange hollow fiber membrane, was used for the experiments. With this low-temperature technique, the wet morphology of the water-absorbable sulfonated polyethylene hollow fiber membrane was revealed. The results obtained from this investigation offer some important information to explain the behavior of the SPE hollow fiber membranes when they are applied in pervaporation separation of water/organic solvent mixtures, such as water/ethylene glycol, water/ethanol, and so forth.

Mast cell proliferation and alterations in bFGF amount and localization are involved in the response of muscle to dystrophin deficiency in hypertrophic feline dystrophy

To test the hypothesis that basic fibroblast growth factor and mast cells play a key role in the phenotypic differences between human dystrophinopathies and hypertrophic feline muscular dystrophy, serial sections of dystrophin-deficient, carrier and normal cat muscle biopsy specimens were examined. They were stained immunohistochemically for dystrophin and different markers of differentiation such as desmin, vimentin and utrophin. Basic fibroblast growth factor was increased in the myofibers of dystrophic cats compared to normal controls and carriers. An association of basic fibroblast growth factor with fiber regeneration and necrosis was shown. The amount of mast cells was markedly increased in muscle tissue of dystrophic cats with a clear predominance of tryptase-positive cells present in large amounts in the endomysium. Mast cells, like basic fibroblast growth factor, were concentrated in areas of muscle fiber regeneration and necrosis. Our data concerning basic fibroblast growth factor and mast cells are consistent with a highly abnormal cellular environment in feline dystrophic muscle with very high levels of basic fibroblast growth factor which is likely modulated by mast cells.

Characterization of a Rhodobacter capsulatus reaction center mutant that enhances the distinction between spectral forms of the initial electron donor

A large scale mutation of the Rhodobacter capsulatus reaction center M-subunit gene, sym2-1, has been constructed in which amino acid residues M205-M210 have been changed to the corresponding L subunit amino acids. Two interconvertable spectral forms of the initial electron donor are observed in isolated reaction centers from this mutant. Which conformation dominates depends on ionic strength, the nature of the detergent used, and the temperature. Reaction centers from this mutant have a ground-state absorbance spectrum that is very similar to wild-type when measured immediately after purification in the presence of high salt. However, upon subsequent dialysis against a low ionic strength buffer or the addition of positively charged detergents, the near-infrared spectral band of P (the initial electron donor) in sym2-1 reaction centers is shifted by over 30 nm to the blue, from 852 to 820 nm. Systematically varying either the ionic strength or the amount of charged detergent reveals an isobestic point in the absorbance spectrum at 845 nm. The wild-type spectrum also shifts with ionic strength or detergent with an isobestic point at 860 nm. The large spectral separation between the two dominant conformational forms of the sym2-1 reaction center makes detailed measurements of each state possible. Both of the spectral forms of P bleach in the presence of light. Electrochemical measurements of the P/P+ midpoint potential of sym2-1 reaction centers show an increase of about 30 mV upon conversion from the long-wavelength form to the short-wavelength form of the mutant. The rate constant of initial electron transfer in both forms of the mutant reaction centers is essentially the same, suggesting that the spectral characteristics of P are not critical for charge separation. The short-wavelength form of P in this mutant also converts to the long-wavelength form as a function of temperature between room temperature and 130 K, again giving rise to an isobestic point, in this case at 838 nm for the mutant. A similar, though considerably less pronounced spectral change with temperature occurs in wild-type reaction centers, with an isobestic point at about 855 nm, close to that found by titrating with ionic strength or detergent. Fitting the temperature dependence of the sym2-1 reaction center spectrum to a thermodynamic model resulted in a value for the enthalpy of the conformational interconversion between the short- and long-wavelength forms of about -6 kJ/mol and an entropy of interconversion of about -35 J/(K mol). Similar values of enthapy and entropy changes can be used to model the temperature dependence in wild-type. Thus, much of the temperature dependence of the reaction center special pair near-infrared absorbance band can be described as an equilibrium shift between two spectrally distinct conformations of the reaction center.

[Exploration on parameters of TCM syndrome in acute cerebral infarction through investigating active factors of vascular endothelium cells]

OBJECTIVE

To explore the multiple parameters of TCM Syndrome-types and the acute cerebral infarction (ACI) with blood stasis type.

METHODS

Sixty-six acute cerebral infarction patients with blood stasis Syndrome, various vascular active factors such as tissue plasminogen activator (t-PA), the activity of plasminogen activator inhibitor (PAI), the concentration of prostaglandin F1 alpha (6-keto-PGF1 alpha) etc. were determined.

RESULTS

(1) In Incidental Syndrome, those "Phlegm" and "stasis" predominant, mainly manifested as Wind-Phlegm-Blood stasis (WPBS), Qi deficiency-blood stasis (QDBS) and Phlegm-Heat-bowel excess (PHBE) Syndrome all showed t-PA activity lowered, among them, QDBS Syndrome lowered more obviously (P < 0.01); and in fundamental deficiency predominant Syndrome such as Yin-deficiency and Wind-move (YDWM) Syndrome, the active t-PA content increased (P < 0.05); in Liver Yang ascending (LYA) Syndrome and YDWM Syndrome, the 6-keto-PGF1 alpha lowered very significantly. (2) Through regression analysis, although influencing the severity of acute blood stasis was related with 3 factors (t-PA activity, nervous system defect score and age growth), but single factor linear relationship analysis indicated that did not existed positive-negative relationship. (3) Through statistical analysis, the factor influencing nervous system defect scores was positively related with blood stasis score (r = 0.70, P < 0.01).

CONCLUSION

(1) The basis of WPBS, QDBS and PHBE Syndrome mainly was fibrinolytic system activity lowering, and YDWM and LYA Syndrome prostaglandin system activity lowering. Comprehensive analysis of multiple parameters would be helpful to differentiate the ACI blood stasis stage. (2) Single parameter would not help to differentiate the types of ACI blood stasis stage, its change merely denoted the existence of blood stasis, its type should be differentiated after comprehensive analysis. (3) Those influencing nervous system scoring, mainly was blood stasis score, which suggested that the importance of activating blood circulation to remove stasis in preventing and treating ACI. (4) Put forward ACI blood stasis, and the quantification for new standard of Syndrome for discussion.

[Coordination chemistry and Raman spectra of acetylide dianion]

This paper shows the syntheses of double salts of silver acetylide with various soluble silver salts, investigations on the coordination modes of acetylide dianion and their Raman spectra, discussion of the relationship between the coordination chemistry of acetylide dianion and the bind mode of N2 molecule in the FeMoco factor of nitrogenase. The results present that the bind mode of N2 molecule inside the FeMoco factor of nitrogenase is more reasonable.

[The prognostic significance of expression of c-met oncogene and its relation to gastric mucosal lesions]

OBJECTIVE

To determine whether there is a relationship between the expression of c-met oncogene and the stage of gastric mucosal lesions or the prognosis of gastric carcinomas.

METHODS

Expression of c-met was investigated in 169 gastric mucosal lesions by using immunohistochemistry. Survival analysis was studied with the Kaplan-Meier test.

RESULTS

For chronic superficial gastritis, chronic atrophic gastritis, intestinal metaplasia, dysplasia, early gastric carcinomas and advanced gastric carcinomas, the expression rates were 23.5%, 36.8%, 51.5%, 61.3%, 66.7% and 73.7% respectively. The positive rate was higher in intestinal metaplasia, dysplasia and gastric carcinomas than in chronic superficial gastritis (P < 0.05). Expression of c-met increased with the increasing proliferation of gastric mucosa in rank correlation test, which showed a close relationship (P < 0.01). Expression of c-met correlated significantly with histologic type, serosal invasion and lymph node metastases. In particular, the expression of c-met was significantly higher in Borrmann type IV gastric carcinomas (87.5%) than in early gastric carcinomas (66.7%) or Borrmann type I, II (68.7%, P < 0.01). The survival rate of patients with expression of c-met was significantly lower than that of patients without c-met expression.

CONCLUSION

The expression of c-met is associated with proliferation and malignant transformation of gastric mucosa. These results suggest that expression of c-met might be a new prognostic factor in gastric carcinoma.

Dysregulation of apoptosis: a possible mechanism leading to chronic progressive renal histological changes in lupus nephritis

OBJECTIVE

To evaluate apoptosis in lupus nephritis and the relationship between the existence of apoptotic cells in renal tissue and histopathological or clinical changes.

METHODS

Apoptosis was detected by in situ nick-end labeling techniques (TUNEL) in renal biopsies from 25 patients with type IV lupus nephritis (LN), 12 patients with IgA nephropathy IgAN, 4 patients with idiopathic mesangioproliferative glomerulonephritis (MsPGN) and 3 patients with acute poststreptococcal glomerulonephritis (APGN). Normal renal tissue obtained at nephrectomy for hypernephroma in 4 adults was used as control. Proliferating cells were identified by proliferating cell nuclear antigen (PCNA) in these patients.

RESULTS

Compared to other proliferative glomerulonephritis and controls, the patients with lupus nephritis had less apoptotic cells, a higher ratio of PCNA + cells/TdT + cells (P/T) in renal tissues; and their P/T ratio in glomeruli and tubulointerstitium correlated with the chronicity index, r = 0.4983 (P = 0.0132), r = 0.8399 (P < 0.001), r = 0.6614 (P = 0.0033), respectively. P/T ratios in the glomerulus and tubule had a positive correlation with 24-hour urinary protein, r = 0.8554 (P < 0.001) and r = 0.7134 (P = 0.001); and a negative correlation with creatinine clearance (Ccr), r = -0.4880 (P = 0.0133) and r = -0.7229 (P = 0.001), which in tubules positively correlated with serum creatinine (Scr), r = 0.4107 (P = 0.0414).

CONCLUSIONS

Apoptosis is reduced in proliferative lupus nephritis. Intense proliferation without a commensurate increase in apoptosis is a possible mechanism that leads to chronic progressive renal histopathological changes.

Antitumour activity of novel taxanes that act at the same time as cytotoxic agents and P-glycoprotein inhibitors

Taxanes antitumour agents such as paclitaxel and docetaxel represent a successful family of chemotherapeutic drugs. Unfortunately, acquired and innate resistance represents a clinical problem for these drugs. We investigated, on a panel of 7 human cancer cell lines, the growth inhibition effect of 3 newly developed taxanes (SB-T-1213, SB-T-1250 and SB-T-101187) with modification at the C10 and C3' positions of the taxane framework. These positions have been previously characterized as critical to make taxanes highly active against cells overexpressing the efflux pump P-glycoprotein (P-gp). Paclitaxel and docetaxel were used as reference compounds. Results unambiguously indicate the exceptional activity of the novel taxanes toward P-gp positive cells (up to >400 fold higher potency than that of paclitaxel). SB-T-1213 and SB-T-1250 are also substantially more active than the reference compounds against P-gp negative cells. To better understand the mechanisms underlying the enhanced activity of the newly developed taxanes, we performed cell cycle and apoptosis analysis. This study demonstrates that the striking growth inhibition effect exhibited by the novel taxanes is ascribed to their increased ability in inducing apoptosis and G(2)/M cell cycle block. SB-T-1213 and SB-T-1250 are also more active than reference compounds in inducing intracellular accumulation of the beta-tubulin subunits. Finally, it is revealed that these novel taxanes have ability to inhibit the function of the P-gp efflux pump on the basis of the Rhodamine 123 assay. These findings strongly suggest that SB-T-1213, SB-T-1250 and SB-T-101187 represent a new tool to overcome innate or acquired P-gp mediated taxane-resistance.

Molecular cloning and antiserum development of cyclin box in the brown tide alga Aureococcus anophagefferens

Cyclins can be useful cell cycle markers for growth rate studies on harmful algal blooms. In this study, a gene fragment corresponding to cyclin box was cloned for the brown tide alga Aureococcus anophagefferens. This algal gene fragment, designated as Btcycl1, was most similar to cyclin B. Oligopeptides based on the deduced amino acid sequence were synthesized and used to raise an antiserum that reacted on Western blots with a protein of about 63 kDa, the same size as cyclin B in other organisms. The cyclin B-like protein recognized by this antiserum, and the messenger RNA amplified using the primers, were more abundant in exponential cultures and decreased markedly in stationary cultures. This protein also appeared to be cell cycle dependent. Immunofluorescence labeling showed that this antiserum specifically stained a protein in Aureococcus cells and had no cross-reaction with bacteria that were present in the algal culture. The Btcycl1 sequence and the antiserum will provide a useful tool for studies on regulation of in situ growth rate for this brown tide alga.

Plasma CPU-86017 concentrations regarding suppression of ouabain-induced cardiac arrhythmias and decrease of heart rate in guinea pigs

AIM

To determine the effective plasma levels of CPU-86017 which could suppress the cardiac arrhythmias induced by i.v. ouabain in guinea pigs.

METHODS

The cardiac arrhythmias and the heart rate were monitored by ECG traces. Blood samples were collected to determine plasma levels using HPLC assay. TXB2 and 6-keto-PGF1 alpha were measured in plasma.

RESULTS

The plasma concentrations of CPU-86017 which were effective to suppress ventricular fibrillation (VF) and heart rate were 0.13-0.23 mg/L and 0.13-0.31 mg/L, respectively. A reduction of TXB2 levels and an elevation of 6-keto-PGF1 alpha levels were observed after CPU-86017 i.v. administration.

CONCLUSION

The arrhythmia-suppressing and heart rate-slowing effect of CPU-86017 followed a linear relationship with its concentrations in plasma.

Down-regulation of cyclin D1 expression by prostaglandin A(2) is mediated by enhanced cyclin D1 mRNA turnover

Prostaglandin A(2) (PGA(2)), an experimental chemotherapeutic agent, causes growth arrest associated with decreased cyclin D1 expression in several cancer cell lines. Here, using human non-small-cell lung carcinoma H1299 cells, we investigated the mechanisms whereby PGA(2) down-regulates cyclin D1 expression. Transcription rates of the cyclin D1 gene, studied using a cyclin D1 promoter-luciferase construct and nuclear run-on assays, were not affected by PGA(2) treatment. Instead, the cyclin D1 mRNA was rendered unstable after exposure to PGA(2). Since the stability of labile mRNA is modulated through binding of proteins to specific mRNA sequences, we sought to identify protein(s) recognizing the cyclin D1 mRNA. In electrophoretic mobility-shift assays using radiolabeled RNA probes derived from different regions of cyclin D1 mRNA, we observed that (i) lysates prepared from PGA(2)-treated cells exhibited enhanced protein-cyclin D1 RNA complex formation; (ii) the kinetics of complex formation correlated closely with that of cyclin D1 mRNA loss; and (iii) binding occurred within a 390-base cyclin D1 3' untranslated region (UTR) (K12). This binding activity could be cross-linked, revealing proteins ranging from 30 to 47 kDa. The RNA-binding protein AUF1, previously associated with the degradation of target mRNAs, bound cyclin D1 mRNA, because anti-AUF1 antibodies were capable of supershifting or immunoprecipitating cyclin D1 mRNA-protein complexes. Finally, insertion of K12 in the 3'UTR of reporter genes markedly reduced the expression and half-life of the resulting chimeric mRNAs in transfected, PGA(2)-treated cells. Our data demonstrate that PGA(2) down-regulates cyclin D1 expression by decreasing cyclin D1 mRNA stability and implicates a 390-base element in the 3'UTR in this regulation.

The swelling behavior and wet morphology of water-absorbable polymer materials

In this research work, a low-temperature examination method for scanning electron microscopy (SEM) is introduced. A water-absorbable polymer material, the sulfonated polyethylene (SPE) ion-exchange hollow fiber membrane, was used for the experiments. With this low-temperature technique, the wet morphology of the water-absorbable sulfonated polyethylene hollow fiber membrane was revealed. The results obtained from this investigation offer some important information to explain the behavior of the SPE hollow fiber membranes when they are applied in pervaporation separation of water/organic solvent mixtures, such as water/ethylene glycol, water/ethanol, and so forth.