Can serum IgE or blood eosinophil count predict postoperative oral corticosteroid response in chronic rhinosinusitis with nasal polyps?

BACKGROUND: Chronic rhinosinusitis with nasal polyps (CRSwNP) is characterised by inflammatory mucosa and polyp formation in the paranasal sinuses. The study's primary objective was to evaluate the outcomes of postoperative oral corticosteroid (OCS) in treating patients with bilateral CRSwNP. The secondary objective was to determine whether preoperative serum IgE levels (sIgE)and/or blood eosinophil count (BEC) correlate with postoperative outcomes following OCS use. METHODS: Patients with bilateral CRSwNP (n=236) who underwent endoscopic sinus surgery (ESS) were randomly assigned to receive 15 mg OCS twice daily or a placebo for 2 weeks. We investigated the treatment effects based on the subjective visual analogue scale (VAS), Sino-Nasal Outcome Test 22 (SNOT-22), and objective Lund-Kennedy Endoscopy Score (LKES) over 6 months; subgroups were stratified preoperatively as follows: sIgE <150 IU/mL, sIgE>=150 IU/mL, BEC <0.39x10(9) cells/L, and BEC>=0.39x10(9) cells/L. RESULTS: A total of 193 participants completed the study up to the 6-month follow-up; no apparent linear relationship was noted between sIgE and BEC. No significant differences in scores were noted upon assessment of the VAS, SNOT-22, and LKES among the follow-up timepoints in the primary analysis. However, in the primary or subgroup analyses with sIgE or BEC, significant differences in the longitudinal scores of sleep dysfunction were observed at the 1-month follow-up. CONCLUSION: Postoperative OCS did not significantly affect bilateral CRSwNP outcomes. sIgE levels and BEC may not be surrogate predictive biomarkers to assess the role of postoperative OCS use. OCS may increase the risk of transient sleep disturbance.

Spatiotemporal control of estrogen-responsive transcription in ERα-positive breast cancer cells.

Recruitment of transcription machinery to target promoters for aberrant gene expression has been well studied, but underlying control directed by distant-acting enhancers remains unclear in cancer development. Our previous study demonstrated that distant estrogen response elements (DEREs) located on chromosome 20q13 are frequently amplified and translocated to other chromosomes in ERα-positive breast cancer cells. In this study, we used three-dimensional interphase fluorescence in situ hybridization to decipher spatiotemporal gathering of multiple DEREs in the nucleus. Upon estrogen stimulation, scattered 20q13 DEREs were mobilized to form regulatory depots for synchronized gene expression of target loci. A chromosome conformation capture assay coupled with chromatin immunoprecipitation further uncovered that ERα-bound regulatory depots are tethered to heterochromatin protein 1 (HP1) for coordinated chromatin movement and histone modifications of target loci, resulting in transcription repression. Neutralizing HP1 function dysregulated the formation of DERE-involved regulatory depots and transcription inactivation of candidate tumor-suppressor genes. Deletion of amplified DEREs using the CRISPR/Cas9 genomic-editing system profoundly altered transcriptional profiles of proliferation-associated signaling networks, resulting in reduction of cancer cell growth. These findings reveal a formerly uncharacterized feature wherein multiple copies of the amplicon congregate as transcriptional units in the nucleus for synchronous regulation of function-related loci in tumorigenesis. Disruption of their assembly can be a new strategy for treating breast cancers and other malignancies.

Effectiveness of oral and intravenous iron therapy in haemodialysis patients.

Anaemia is a common and serious complication in patients with end-stage renal disease. Iron therapy is crucial in managing anaemia and maintenance of haemodialysis (HD) patients. This study investigated the efficacy of both oral and intravenous (i.v.) therapies, and the possible factors deleteriously affecting patient response to iron therapy. Forty patients on maintenance HD from a single institution were enrolled in this 6-month retrospective study. Group I (n = 20) received i.v. two ampoules of atofen (ferric chloride hexahydrate 193.6 mg) per week for a total of 6 weeks (total dosage, 960 mg). Group II (n = 20) received oral ferrous sulphate S.C. Tab (ferrous sulphate 324 mg) one pill three times daily (total dosage, 63,000 mg). Patients whose haematocrit (Hct) level increased at minimum 3% within the period were classified as responders. Iron i.v. ferric chloride (960 mg) was more effective than oral ferrous sulphate (63,000 mg) in correcting anaemia in HD patients with iron deficiency. In group I, serum triglyceride (TG) levels were significantly lower in patients responding to i.v. iron therapy than in patients with no response. In group II, serum high-sensitive C-reactive protein (hs-CRP) level was significantly lower in patients responding to oral iron therapy than patients with no response. The i.v. ferric chloride is more effective than oral ferrous sulphate in treating anaemia in HD patients with iron deficiency. Serum hs-CRP and TG levels may be parameters for predicting hyporesponsiveness to oral and i.v. iron therapies, respectively.

Certifying diabetes-related cause-of-death: a comparison of inappropriate certification statements in Sweden, Taiwan and the USA.

AIMS/HYPOTHESIS: The aim of this study was to assess differences in the certification practices of physicians in Sweden, Taiwan and the USA with regard to diabetes-related cause-of-death (COD) statements. METHODS: Multiple-cause-of-death data from Sweden (2000), Taiwan (2001) and the USA (2001) were used for this study. All deaths with mention of diabetes anywhere on the death certificate were extracted for analysis. Two types of inappropriate COD statements were: (1) reporting two or more diagnoses per line; and (2) entering an incorrect causal sequence among reported diagnoses. RESULTS: Of those deaths in which diabetes was reported in Part I of the death certificate, American physicians (19%) were less likely to report two or more diagnoses per line than physicians in Sweden (46%) and Taiwan (56%). On the other hand, Swedish physicians (5%) were less likely to report incorrect causal sequences than were their counterparts in Taiwan (21%) and the USA (28%). CONCLUSIONS/INTERPRETATION: These findings reveal substantial differences in diabetes-related COD statements among physicians in Sweden, Taiwan and the USA, implying that caution should be used when interpreting differences in mortality statistics between these countries.

Co-expression of RON and MET is a prognostic indicator for patients with transitional-cell carcinoma of the bladder.

Recepteur d'Origine Nantais (RON) is a distinct receptor tyrosine kinase in the c-met proto-oncogene family. We examined the mutational and expression patterns of RON in eight human uroepithelial cell lines. Biological effects of RON overexpression on cancer cells were investigated in vitro, and the prognostic significance of RON and/or c-met protein (MET) expression was analysed in a bladder cancer cohort (n=183). There was no evidence of mutation in the kinase domain of RON. Overexpression of RON using an inducible Tet-off system induced increased cell proliferation, motility, and antiapoptosis. Immunohistochemical analysis showed that RON was overexpressed in 60 cases (32.8%) of primary tumours, with 14 (23.3%) showing a high level of expression. Recepteur d'Origine Nantais expression was positively associated with histological grading, larger size, nonpapillary contour, and tumour stage (all P<0.01). In addition, MET was overexpressed in 82 cases (44.8%). Co-expressed RON and MET was significantly associated with decreased overall survival (P=0.005) or metastasis-free survival (P=0.01) in 35 cases (19.1%). Recepteur d'Origine Nantais-associated signalling may play an important role in the progression of human bladder cancer. Evaluation of RON and MET expression status may identify a subset of bladder-cancer patients who require more intensive treatment.

Phenotypic variability in a Chinese family with rimmed vacuolar distal myopathy.

BACKGROUND: UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE) gene mutations have been found in patients with distal myopathy with rimmed vacuoles (DMRV). It is not clear how the same GNE gene mutations can result in different phenotypes in the same family with DMRV. METHODS: The clinical, neurophysiological, histopathological, and genetic characteristics of two patients with DMRV from a Chinese family from Taiwan were investigated. RESULTS: Two novel compound heterozygous mutations in different domains of the protein, Ile241Ser in the epimerase and Trp513stop in the kinase domain, were detected in both patients. However, the two patients demonstrated different patterns of disease progression: one had slow disease progression with a typical feature of DMRV (that is, weakness beginning in the distal leg muscles, typically anterior tibialis, with the quadriceps remaining relatively unaffected), and the other had rapid disease progression with an atypical presentation of DMRV. CONCLUSIONS: The results of the present study indicate that GNE gene mutations and probably modifier gene(s) or additional factors may result in different phenotypes of DMRV.

The first total synthesis of (+/-)-eremopetasidione.

[figure: see text] The total synthesis of racemic eremopetasidione, a norsesquiterpenoid, has been achieved in nine steps and 30% overall yield starting from creosol (5). Diels-Alder reaction of masked o-benzoquinone 6 and ethyl vinyl ketone and Cope rearrangement of 2-silyloxy-1,5-dienone 3 are the key steps.

Substrate binding is the rate-limiting step in thromboxane synthase catalysis.

Thromboxane synthase (TXAS) is a "non-classical" cytochrome P450. Without any need for an external electron donor, or for a reductase or molecular oxygen, it uses prostaglandin H2 (PGH2) to catalyze either an isomerization reaction to form thromboxane A2 (TXA2) or a fragmentation reaction to form 12-l-hydroxy-5,8,10-heptadecatrienoic acid and malondialdehyde (MDA) at a ratio of 1:1:1 (TXA2:heptadecatrienoic acid:MDA). We report here kinetics of TXAS with heme ligands in binding study and with PGH2 in enzymatic study. We determined that 1) binding of U44069, an oxygen-based ligand, is a two-step process; U44069 first binds TXAS, then ligates the heme-iron with a maximal rate constant of 105-130 s(-1); 2) binding of cyanide, a carbon-based ligand, is a one-step process with k(on) of 2.4 M(-1) s(-1) and k(off) of 0.112 s(-1); and 3) both imidazole and clotrimazole (nitrogen-based ligands) bind TXAS in a two-step process; an initial binding to the heme-iron with on-rate constants of 8.4 x 10(4) M(-1) s(-1) and 1.5 x 10(5) M(-1) s(-1) for imidazole and clotrimazole, respectively, followed by a slow conformational change with off-rate constants of 8.8 s(-1) and 0.53 s(-1), respectively. The results of our binding study indicate that the TXAS active site is hydrophobic and spacious. In addition, steady-state kinetic study revealed that TXAS consumed PGH2 at a rate of 3,800 min(-1) and that the k(cat)/K(m) for PGH2 consumption was 3 x 10(6) M(-1) s(-1). Based on these data, TXAS appears to be a very efficient catalyst. Surprisingly, rapid-scan stopped-flow experiments revealed marginal absorbance changes upon mixing TXAS with PGH2, indicating minimal accumulation of any heme-derived intermediates. Freeze-quench EPR measurements for the same reaction showed minimal change of heme redox state. Further kinetic analysis using a combination of rapid-mixing chemical quench and computer simulation showed that the kinetic parameters of TXAS-catalyzed reaction are: PGH2 bound TXAS at a rate of 1.2-2.0 x 10(7) M(-1) s(-1); the rate of catalytic conversion of PGH2 to TXA2 or MDA was at least 15,000 s(-1) and the lower limit of the rates for products release was 4,000-6,000 s(-1). Given that the cellular PGH2 concentration is quite low, we concluded that under physiological conditions, the substrate-binding step is the rate-limiting step of the TXAS-catalyzed reaction, in sharp contrast with "classical" P450 enzymes.

Identification of thromboxane synthase amino acid residues involved in heme-propionate binding.

Thromboxane A2 synthase (TXAS) is a member of the cytochrome P450 superfamily and catalyzes an isomerization reaction that converts prostaglandin H2 to thromboxane A2. As a step toward understanding the structure/function relationships of TXAS, we mutated amino acid residues predicted to bind the propionate groups of A- and D-pyrrole rings of the heme. These mutations at each of these residues (Asn-110, Trp-133, Arg-137, Arg-413, and Arg-478) resulted in altered heme binding, as evidenced by perturbation of the absorption spectra and EPR. The mutations, although causing no significant changes in the secondary structure of the proteins, induced tertiary structural changes that led to increased susceptibility to trypsin digestion and alteration of the intrinsic protein fluorescence. Moreover, these mutant proteins lost their binding affinity to the substrate analog, had a lower heme content and retained less than 5% of the wild-type catalytic activity. However, mutations at the neighboring amino acid of the aforementioned residues yielded mutant proteins retaining the biochemical and biophysical properties of the wild type TXAS. Aligning the TXAS sequence with the structurally known P450s, we proposed that in TXAS the A-ring propionate of the heme is hydrogen bonded to Asn-110, Arg-413, and Arg-478, whereas D-ring propionate is hydrogen bonded to Trp-133 and Arg-137. Furthermore, both A- and D-ring propionates bulge away from the heme plane and both lie on the proximal face of heme plane, a structure similar to P450terp.

Expression, purification, and spectroscopic characterization of human thromboxane synthase.

Thromboxane A2 (TXA2) is a potent inducer of vasoconstriction and platelet aggregation. Large scale expression of TXA2 synthase (TXAS) is very useful for studies of the reaction mechanism, structural/functional relationships, and drug interactions. We report here a heterologous system for overexpression of human TXAS. The TXAS cDNA was modified by replacing the sequence encoding the first 28 amino acid residues with a CYP17 amino-terminal sequence and by adding a polyhistidine tag sequence prior to the stop codon; the cDNA was inserted into the pCW vector and co-expressed with chaperonins groES and groEL in Escherichia coli. The resulting recombinant protein was purified to electrophoretic homogeneity by affinity, ion exchange, and hydrophobic chromatography. UV-visible absorbance (UV-Vis), magnetic circular dichroism (MCD), and electron paramagnetic resonance (EPR) spectra indicate that TXAS has a typical low spin cytochrome P450 heme with an oxygen-based distal ligand. The UV-Vis and EPR spectra of recombinant TXAS were essentially identical to those of TXAS isolated from human platelets, except that a more homogenous EPR spectrum was observed for the recombinant TXAS. The recombinant protein had a heme:protein molar ratio of 0.7:1 and a specific activity of 12 micromol of TXA2/min/mg of protein at 23 degreesC. Furthermore, it catalyzed formation of TXA2, 12-hydroxy-5,8,10-heptadecatrienoic acid, and malondialdehyde in a molar ratio of 0.94:1.0:0.93. Spectral binding titrations showed that bulky heme ligands such as clotrimazole bound strongly to TXAS (Kd approximately 0.5 microM), indicating ample space at the distal face of the heme iron. Analysis of MCD and EPR spectra showed that TXAS was a typical low spin hemoprotein with a proximal thiolate ligand and had a very hydrophobic distal ligand binding domain.

Identification of thromboxane A2 synthase active site residues by molecular modeling-guided site-directed mutagenesis.

Human thromboxane A2 synthase (TXAS) exhibits spectral characteristics of cytochrome P450 but lacks monooxygenase activity. Its distinctive amino acid sequence makes TXAS the sole member of family 5 in the P450 superfamily. To better understand the structure-function relationship of this unusual P450, we have recently constructed a three-dimensional model for TXAS using P450BM-3 as the template (Ruan, K.-H., Milfeld, K., Kulmacz, R. J., and Wu, K. K. (1994) Protein Eng. 7, 1345-1551) and have identified a potential active site region. The catalytic roles of several putative active site residues were evaluated using selectively mutated recombinant TXAS expressed in COS-1 cells. Mutation of Ala-408 to Glu or Arg-413 to Gly led to a complete loss of enzyme activity despite expression of mutant protein levels equivalent to that of the wild-type TXAS. Mutation of Ala-408 to Gly or Leu retained the enzyme activity at levels of 30 or 40%, respectively. This suggests that Ala-408 provides a hydrophobic environment for substrate binding. Mutation of Arg-413 to Lys or Gln completely abolished the enzyme activity, indicating that this residue is essential to catalytic activity and supports its identification as an active site residue. Mutation of Arg-410 to Gly or Glu-433 to Ala resulted in >50% reduction in the enzyme activity without appreciably altering mutant protein expression, consistent with a more subtle effect of these residues on TXAS catalytic efficiency. Mutation of residues predicted to be involved in binding the heme prosthetic group, including the heme thiolate ligand Cys-480, Arg-478, Phe-127, and Asn-110, each markedly reduced the expressed protein level and abolished enzyme activity. This suggests that proper heme binding is important to synthesis or stability of recombinant TXAS. Mutation of Ile-346, which corresponds to P450cam-Thr-252, an essential amino acid involved in dioxygen bond scission, to Thr increased the enzymatic activity by 40%, suggesting that oxygen bond cleavage is not a rate-limiting step in thromboxane A2 biosynthesis. The present results from site-directed mutagenesis support the overall structure of the TXAS active site predicted by homology modeling and have allowed refinement of the position of bound substrate.

NarK enhances nitrate uptake and nitrite excretion in Escherichia coli.

narK mutants of Escherichia coli produce wild-type levels of nitrate reductase but, unlike the wild-type strain, do not accumulate nitrite when grown anaerobically on a glucose-nitrate medium. Comparison of the rates of nitrate and nitrite metabolism in cultures growing anaerobically on glucose-nitrate medium revealed that a narK mutant reduced nitrate at a rate only slightly slower than that in the NarK+ parental strain. Although the specific activities of nitrate reductase and nitrite reductase were similar in the two strains, the parental strain accumulated nitrite in the medium in almost stoichiometric amounts before it was further reduced, while the narK mutant did not accumulate nitrite in the medium but apparently reduced it as rapidly as it was formed. Under conditions in which nitrite reductase was not produced, the narK mutant excreted the nitrite formed from nitrate into the medium; however, the rate of reduction of nitrate to nitrite was significantly slower than that of the parental strain or that which occurred when nitrite reductase was present. These results demonstrate that E. coli is capable of taking up nitrate and excreting nitrite in the absence of a functional NarK protein; however, in growing cells, a functional NarK promotes a more rapid rate of anaerobic nitrate reduction and the continuous excretion of the nitrite formed. Based on the kinetics of nitrate reduction and of nitrite reduction and excretion in growing cultures and in washed cell suspensions, it is proposed that the narK gene encodes a nitrate/nitrite antiporter which facilitates anaerobic nitrate respiration by coupling the excretion of nitrite to nitrate uptake. The failure of nitrate to suppress the reduction of trimethylamine N-oxide in narK mutants was not due to a change in the level of trimethylamine N-oxide reductase but apparently resulted from a relative decrease in the rate of anaerobic nitrate reduction caused by the loss of the antiporter system.

Roles of the narJ and narI gene products in the expression of nitrate reductase in Escherichia coli.

Nitrate reductase, released and purified from membrane fractions of Escherichia coli, is composed of three subunits. Formation of the enzyme depends on induction of the nar operon, narGHJI, which is composed of four open reading frames (ORF). Previous studies established that the first two genes in the operon narG and narH encode the alpha and beta subunits, respectively, while formation of the gamma subunit, cytochrome bNR, depends on expression of the promoter distal genes. The narJ and narI genes were subcloned separately into plasmids where each was under the control of the nar promoter. Expression of these plasmids in a mutant which forms only alpha and beta subunits revealed that expression of the narI gene is sufficient to restore normal levels of cytochrome bNR, but expression of both genes is required for assembly of fully active, membrane-bound nitrate reductase. The amino acid composition, the N-terminal sequence, and the sequence of cyanogen bromide fragments derived from the isolated gamma subunit corresponds to that expected for a protein produced by the narI ORF. A protein corresponding to the narJ ORF did not appear to be associated with the purified nitrate reductase complex or with the complex immunoprecipitated from Triton X-100-solubilized membrane preparations. We conclude that narI encodes the gamma subunit (cytochrome bNR) and that while the product of the narJ gene is required for assembly of fully active membrane-bound enzyme it is not tightly associated with the active enzyme.

Construction in vitro of a cloned nar operon from Escherichia coli.

To clone the nar operon of Escherichia coli without an effective selection procedure for the nar+ phenotype, a strategy utilizing nar::Tn5 mutants was employed. Partial segments of the nar operon containing Tn5 insertions were cloned into plasmid pBR322 by using the transposon resistance character for selection. A hybrid plasmid was constructed in vitro from two of these plasmids and isolated by a procedure that involved screening a population of transformed nar(Ts) mutant TS9A for expression of thermal stable nitrate reductase activity. A detailed restriction site map of the resulting plasmid, pSR95, corresponded closely to the composite restriction endonuclease map deduced for the nar region from maps of the cloned nar::Tn5 fragments. When transformed with pSR95, wild-type strain PK27 overproduced the alpha, beta, and gamma subunits of nitrate reductase, although nitrate reductase activity was only slightly increased. The alpha and beta subunits were overproduced about 5- to 10-fold and accumulated mostly as an inactive aggregate in the cytoplasm; the gamma subunit overproduction was detected as a threefold increase in the specific content of cytochrome b555 in the membrane fraction. Functional nitrate reductase and the cytochrome spectrum associated with functional nitrate reductase were restored in the nar::Tn5 mutant EE1 after transformation with pSR95. Although the specific activity of nitrate reductase in this case was less than that of the wild type, both the alpha and beta subunits appeared to be overproduced in an inactive form. In both strains PK27(pSR95) and EE1(pSR95), the formation of nitrate reductase activity and the accumulation of inactive subunits were repressed during aerobic growth. From these observations and the accumulation of inactive subunits were repressed during aerobic growth. From these observations and the demonstration that pSR95 contains a functional nor operon that encodes the alpha, beta, gamma subunits of nitrate reductase.

Purification of calciferol-binding proteins from kidney: physicochemical and immunological properties.

The calciferol-binding system of rat kidney cytosol has been purified and is shown to consist of two proteins, each capable of binding either 25-hydroxy-vitamin D3 (25-OH-D3) or 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3). The two proteins, designated A and B, have similar sedimentation coefficients (S20w) of 5.2 S. Component A binds 25-OH-D3 with a dissociation constant (Kd) of 10(-7) M while component B binds 1,25-(OH)2D3 with a Kd of 1.6 x 10(-8) M. The estimated molecular weights (Mr) of the two proteins are 105,000 for component A and 250,000 for component B. Amino acid analyses revealed that glutamic acid is the most abundant residue in both proteins, comprising 12% of the total number of amino acid residues. Immunodiffusion test using commercial anti-human serum group-specific protein antiserum gave a precipitin reaction when purified rat serum calciferol-binding protein was used as an antigen, but no reactions could be detected with proteins A and B. This result significantly eliminated the possibility of the presence of the rat serum binding protein in either of the purified kidney proteins. In contrast, anti-rat serum calciferol-binding protein antiserum prepared in rabbits interacted with the rat serum and kidney proteins. This result suggests that the antigenic determinants recognized by the antiserum against the rat serum calciferol-binding protein appear to be similar to those recognized in the kidney proteins A and B. Immunoelectrophoresis of the three rat proteins demonstrated dissimilar electrophoretic mobilities with the serum protein showing the least mobility, a property consistent with its higher lysine content relative to proteins A and B.

Changes in lymphoid cyclic adenosine 3':5'-monophosphate metabolism during murine leukemogenesis.

Cyclic adenosine 3':5'-monophosphate (cyclic AMP) levels were slightly increased in preleukemic AKR mouse thymus cells, compared with nonleukemic thymus cells, but were markedly reduced in leukemic cells. Adenylate cyclase activity rose during the preleukemic and leukemic phases of leukemogenesis. Although the drop of epinephrine-induced stimulation of thymus adenylate cyclase in the preleukemic phase was probably age related, there was an additional decrease of adenylate cyclase activation by epinephrine in leukemic cells. Cyclic AMP phosphodiesterase activity was slightly higher in preleukemic cells and more than fourfold AKR thymus. These observations suggest that cyclic AMP phosphodiesterase is largely responsible for the low levels of cyclic AMP in leukemic cells. Significant changes in cyclic AMP metabolism are already detectable before neoplastic cells may be found in the thymus.