Cloning and expression of the EP2 subtype of human receptors for prostaglandin E2

Prostaglandin E2 (PGE2) is a potent mediator in many human tissues, that is recognized by three distinct subtypes of receptors, designated EP1, EP2 and EP3. A cDNA from a human lung library encodes a 53 kDa protein of 88% homology with the mouse EP2 receptor. Human EP2 receptors in COS-7 cell transfectants bound [3H]-PGE2 with a mean Kd of 2.2 nM and native specificity, and transduced increases in the intra-cellular concentration of cyclic AMP, but not of Ca++. That most EP2 receptor mRNA is in lung, kidney, intestinal, glandular and immune tissues, is consistent with functional responses.

Lysis of autologous melanoma cells by tumor-infiltrating lymphocytes: association with clinical response

Tumor-infiltrating lymphocytes (TILs) can be grown in vitro in medium containing interleukin-2 (IL-2). In clinical trials at the Surgery Branch of the National Cancer Institute, patients with metastatic malignant melanomas were treated with IL-2 plus the adoptive transfer of autologous TILs. At the time of treatment, TILs were assayed for in vitro lysis of fresh autologous and allogeneic melanoma cells and Daudi cells. Patients were evaluated for clinical response 4-8 weeks later. Lysis of autologous tumor cells by TILs was significantly higher for responding than for nonresponding patients. Tumor cells from responding and nonresponding patients were equally sensitive to lysis by allogeneic lymphokine-activated killer (LAK) cells. There was no difference between TILs from responding and nonresponding patients for lysis of LAK-sensitive Daudi cells, which was low in most cases and demonstrated that TIL lysis of autologous tumor cells was not due to LAK cells. The observed association of autologous tumor cell lysis by TILs with clinical response suggests that the development of culture methods to optimize lysis of autologous tumors may lead to increased response rates using this TIL treatment regimen.

Triptolide induces apoptotic death of T lymphocyte

Extract of Tripterygium wilfordii Hook. f (TWHf) has immunosuppressive activity and has been used as anti-inflammatory agent in traditional Chinese medicine for centuries. Recent studies have demonstrated that triptolide is the major active component in the extract that inhibits antigen or mitogen-induced T cell proliferation. In attempting to investigate its effect on activation of T lymphocytes, we found triptolide induces apoptotic death of T cell hybridomas and peripheral T cells but not that of thymocytes. The triptolide-induced apoptosis is accompanied by increase of DEVD-cleavable caspases activity and degradation of caspase substrate poly (ADP-ribose) polymerase (PARP). A specific inhibitor of caspases, zVAD-FMK, prevents triptolide-induced PARP degradation and DNA fragmentation but not growth arrest. Furthermore, enforced expression of Bcl-2 inhibited triptolide-induced degradation of PARP and apoptosis. These results indicate that triptolide induces T cell apoptosis through activating caspases, and suggest the growth arrest and apoptotic effect of triptolide may contribute to the immunosuppressive activity of TWHf extract.

Sustained growth in primary culture of normal mammary epithelial cells embedded in collagen gels

Normal mammary epithelial cells from BALB/cfC3H midpregnant mice were freed from stromal cell types by Percoll density gradient centrifugation after collagenase digestion and were then embedded within collagen gels. Sustained growth leading to an increase in cell number was accomplished in response to cholera toxin and high concentrations of horse serum. The extent of growth was found to be dependent on the horse serum concentration, the maximum growth being attained at 50%. A serum concentration of 12.5% horse serum and 2.5% fetal calf serum, along with cholera toxin at 0.01 mug/ml, allowed maintenance but failed to cause any significant increase in cell number during the experimental period of 2 weeks. This same maintenance medium was used to determine the effects of various exogenously added steroids, protein hormones, and organ extracts on the proliferation of mammary epithelial cells in culture. Hormones failed to elicit any proliferative response, but extracts of kidney, brain, uterus, and spleen produced proliferative responses equal to or greater than the response obtained with 50% horse serum and cholera toxin. Kidney extracts prepared from midpregnant mice, virgin mice, and virgin mice given pituitary isografts all showed comparable activities, suggesting that the concentration of stimulatory factor(s) was not influenced by the hormonal status of the donor. Normal mammary epithelial cells that had undergone a 10- to 15-fold increase in cell number over initial values during 2-3 weeks in culture were passaged to secondary gel cultures. Outgrowth similar to those seen in primary culture were seen again in secondary culture. The present system provides a method for sustaining growth in culture of primary mammary epithelial cells from normal tissues.

Micropatterned agarose gels for stamping arrays of proteins and gradients of proteins

We describe a method for repetitive and rapid formation of planar microarrays and gradients of proteins using patterned agarose stamps. It demonstrates: (i) micropatterning of agarose gels with feature sizes as small as 2 microm; (ii) inking of posts (diameter 50-1000 microm) on patterned agarose stamps with one or multiple (here, eight) proteins and repetitive stamping of patterns (>100 times in the case of one protein) and arrays (20 times in the case of eight proteins) without the need for intermediate re-inking; (iii) transferring spots of proteins with good homogeneity in surface coverage to glass slides; (iv) applying this technique to surface-based immunoassays; (v) stamping that requires only sub-nanomolar amounts of protein (typically approximately 3 microg in approximately 0.6 microL of solution); (vi) stamping without the need for drying of the proteins, as opposed to stamping with stamps made of poly(dimethylsiloxane); and (vii) patterning gradients of proteins by allowing two proteins to diffuse toward each other in an agarose stamp, followed by printing the protein gradients onto a surface.

Isolation, characterization, and functional analysis of a novel cDNA clone encoding a small rubber particle protein from Hevea brasiliensis

Biochemical evidence reported so far suggests that rubber synthesis takes place on the surface of rubber particles suspended in the latex of Hevea brasiliensis. We have isolated and characterized a cDNA clone that encodes a protein tightly bound on a small rubber particle. We named this protein small rubber particle protein (SRPP). Prior to this study, this protein was known as a latex allergen, and only its partial amino acid sequence was reported. Sequence analysis revealed that this protein is highly homologous to the rubber elongation factor and the Phaseolus vulgaris stress-related protein. Southern and Northern analyses indicate that the protein is encoded by a single gene and highly expressed in latex. An allergenicity test using the recombinant protein confirmed that the cloned cDNA encodes the known 24-kDa latex allergen. Neither ethylene stimulation nor wounding changed the transcript level of the SRPP gene in H. brasiliensis. An in vitro rubber assay showed that the protein plays a positive role in rubber biosynthesis. Therefore, it is likely that SRPP is a part of the rubber biosynthesis machinery, if not the rubber polymerase, along with the rubber elongation factor.

Deleterious effect of CTLA4-Ig on a Treg-dependent transplant model

Blockade of the B7:CD28 costimulatory pathway has emerged as a promising therapy to prevent allograft rejection. However, results from the belatacept phase III clinical trial demonstrated a higher rejection rate when compared to cyclosporine, raising concern about potential deleterious effects of this agent. In this study, we investigated the consequences of B7:CD28 blockade by hCTLA4Ig on regulator T cell (Treg) generation in different major histocompatibility complex (MHC) mismatch transplant models. Administration of hCTLA4Ig significantly decreased the amount of Tregs in B6 WT animals and this effect was predominant in thymus-induced Tregs (Helios(+) ). Although hCTLA4Ig prevented rejection in a fully allogeneic mismatch model, it accelerated rejection in a MHC class-II mismatch model (MST = 26, p < 0.0001), in which long-term allograft survival is dependent on Tregs. This accelerated rejection was associated with a marked reduction in thymus-induced Tregs and led to a higher effector/regulatory T-cell ratio in secondary lymphoid organs and in the allograft. This study confirms the importance of the B7:CD28 pathway in Treg homeostasis in an in vivo transplant model and suggests that hCTLA4Ig therapy may be deleterious in circumstances where engraftment is dependent on Tregs.

Growth factor- and cyclic nucleotide-induced proliferation of normal and malignant mammary epithelial cells in primary culture

Sustained growth of normal mouse mammary epithelial cells in primary culture, leading to an increase in cell number, in response to growth factors [epidermal growth factor (EGF) and fibroblast growth factor (FGF)] or cholera toxin has been achieved by embedding the cells inside collagen cells. Inclusion of agents known to increase the level of cellular cAMP have been found to be favorable for mammary epithelial cell proliferation. Cholera toxin is by far the best of all of the agents tested (prostaglandins E1 and E2, isoproterenol, theophylline, and dibutyryl cAMP). When growth factors (EGF or FGF) are added with cholera toxin, a synergistic effect resulting in a response much greater than with either of them alone is seen. This synergism was best seen in normal mammary epithelial cells from nonpregnant mice. The extent of this synergistic effect was found to be less in normal cells from pregnant mice, suggesting that these cells may be less responsive to EGF during pregnancy. Tumor cells were found to be rather inconsistent in their responses to EGF and cholera toxin, ranging from a minimal response, similar to that of normal cells from pregnant animals, to a maximal response, similar to that of normal cells from nonpregnant animals.

Cardiomyopathy in transgenic mice with cardiac-specific overexpression of serum response factor

Serum response factor (SRF), a member of the MCM1, agamous, deficiens, SRF (MADS) family of transcriptional activators, has been implicated in the transcriptional control of a number of cardiac muscle genes, including cardiac alpha-actin, skeletal alpha-actin, alpha-myosin heavy chain (alpha-MHC), and beta-MHC. To better understand the in vivo role of SRF in regulating genes responsible for maintenance of cardiac function, we sought to test the hypothesis that increased cardiac-specific SRF expression might be associated with altered cardiac morphology and function. We generated transgenic mice with cardiac-specific overexpression of the human SRF gene. The transgenic mice developed cardiomyopathy and exhibited increased heart weight-to-body weight ratio, increased heart weight, and four-chamber dilation. Histological examination revealed cardiomyocyte hypertrophy, collagen deposition, and interstitial fibrosis. SRF overexpression altered the expression of SRF-regulated genes and resulted in cardiac muscle dysfunction. Our results demonstrate that sustained overexpression of SRF, in the absence of other stimuli, is sufficient to induce cardiac change and suggest that SRF is likely to be one of the downstream effectors of the signaling pathways involved in mediating cardiac hypertrophy.

O-glycan biosynthesis in human colorectal adenoma cells during progression to cancer

A human colonic adenoma cell line PC/AA derived from a familial polyposis coli patient was passaged in culture to form an intermediate premalignant clonogenic variant AA/C1 and, upon treatment with differentiating and carcinogenic agents, a cell line AA/C1/SB10 which is tumourigenic in nude mice. These three mucin-secreting cell lines have been used as a model to study the changes in O-glycan biosynthesis during the progression to cancer. Several glycosyltransferases involved in the synthesis, elongation and termination of the common O-glycan core structures were found to decrease in the progression sequence towards adenocarcinoma. Higher activity of a number of enzymes was seen in the intermediate cell line. O-glycan biosynthesis in the original PC/AA cell line was closest to the normal human colonic phenotype, since all four common mucin O-glycan cores and their extended structures could be synthesized; core 3 beta 3-GlcNAc-transferase and alpha 6-sialytransferase acting on GalNAc-mucin were still detectable and core 2 beta 6-GlcNAc-transferase activity was accompanied by core 4 and I beta 6-GlcNAc-transferase activities. During progression towards adenocarcinoma, the expression of alpha 6-sialyltransferase, core 3 beta 3-GlcNAc-transferase, core 4 and I beta 6-GlcNAc-transferases were turned off. Using monoclonal antibodies, Tn antigen, sialyl-Tn antigen, O-acetyl-sialomucin and sialyl-Lea determinants were not detected in secreted or cellular mucin isolated from any of the cell lines. The exposure of MUC1 epitopes was seen in the malignant line, whereas sialyl-Lex determinants were found only in the premalignant PC/AA line. Sulfotransferase activities using core 1 substrate, Gal beta 1-3GalNAc alpha-benzyl, were high in PC/AA cells and progressively decreased upon development to adenocarcinoma, and this decrease correlated with mucin sulfation. In summary, the synthesis of less abundant, sialylated, fucosylated and extended, unbranched core 1 structures should be facilitated in the malignant cells. This is the first report of glycosyltransferase changes in human premalignant cells developing to tumourigenic cells. The data demonstrate that these cell lines are an excellent model to study the changes and regulation of mucin oligosaccharide biosynthesis during progression to cancer.

Identification of the endonuclease domain encoded by R2 and other site-specific, non-long terminal repeat retrotransposable elements

The non-long terminal repeat (LTR) retrotransposon, R2, encodes a sequence-specific endonuclease responsible for its insertion at a unique site in the 28S rRNA genes of arthropods. Although most non-LTR retrotransposons encode an apurinic-like endonuclease upstream of a common reverse transcriptase domain, R2 and many other site-specific non-LTR elements do not (CRE1 and 2, SLACS, CZAR, Dong, R4). Sequence comparison of these site-specific elements has revealed that the region downstream of their reverse transcriptase domain is conserved and shares sequence features with various prokaryotic restriction endonucleases. In particular, these non-LTR elements have a Lys/Arg-Pro-Asp-X12-14aa-Asp/Glu motif known to lie near the scissile phosphodiester bonds in the protein-DNA complexes of restriction enzymes. Site-directed mutagenesis of the R2 protein was used to provide evidence that this motif is also part of the active site of the endonuclease encoded by this element. Mutations of this motif eliminate both DNA-cleavage activities of the R2 protein: first-strand cleavage in which the exposed 3' end is used to prime reverse transcription of the RNA template and second-strand cleavage, which occurs after reverse transcription. The general organization of the R2 protein appears similar to the type IIS restriction enzyme, FokI, in which specific DNA binding is controlled by a separate domain located amino terminal to the cleavage domain. Previous phylogenetic analysis of their reverse transcriptase domains has indicated that the non-LTR elements identified here as containing restriction-like endonucleases are the oldest lineages of non-LTR elements, suggesting a scenario for the evolution of non-LTR elements.

Reduced osmotic water permeability of the peritoneal barrier in aquaporin-1 knockout mice

Aquaporin-1 (AQP1) water channels are expressed widely in epithelia and capillary endothelia involved in fluid transport. To test whether AQP1 facilitates water movement from capillaries into the peritoneal cavity, osmotically induced water transport rates were compared in AQP1 knockout [(-/-)], heterozygous [(+/-)], and wild-type [(+/+)] mice. In (+/+) mice, RT-PCR showed detectable transcripts for AQP1, AQP3, AQP4, AQP7, and AQP8. Immunofluorescence showed AQP1 protein in capillary endothelia and mesangium near the peritoneal surface and AQP4 in adherent muscle plasmalemma. For measurement of water transport, 2 ml of saline containing 300 mM sucrose (600 mosM) were infused rapidly into the peritoneal cavity via a catheter. Serial fluid samples (50 microliter) were withdrawn over 60 min, with albumin as a volume marker. The albumin dilution data showed significantly decreased initial volume influx in AQP1 (-/-) mice: 101 +/- 8, 107 +/- 5, and 42 +/- 4 (SE) microliter/min in (+/+), (+/-), and (-/-) mice, respectively [n = 6-10, P < 0.001, (-/-) vs. others]. Volume influx for AQP4 knockout mice was 100 +/- 8 microliters/min. In the absence of an osmotic gradient, 3H2O uptake [half time = 2.3 and 2.2 min in (+/+) and (-/-) mice, respectively], [14C]urea uptake [half time = 7.9 and 7.7 min in (+/+) and (-/-) mice, respectively], and spontaneous isosmolar fluid absorption from the peritoneal cavity [0.47 +/- 0.05 and 0.46 +/- 0.04 ml/h in (+/+) and (-/-) mice, respectively] were not affected by AQP1 deletion. Therefore, AQP1 provides a major route for osmotically driven water transport across the peritoneal barrier in peritoneal dialysis.

An artificial cytochrome P450 that hydroxylates unactivated carbons with regio- and stereoselectivity and useful catalytic turnovers

A catalyst has been synthesized comprising a manganese porphyrin carrying four beta-cyclodextrin groups. It catalyzes the hydroxylation of substrates of appropriate size carrying tert-butylphenyl groups that can hydrophobically bind into the cyclodextrin cavities. In one example as many as 650 catalytic turnovers are seen before the catalyst is oxidatively destroyed, and with a rate comparable to that of typical cytochrome P450 enzymes. In another example, a steroid derivative is regio- and stereoselectively hydroxylated at a single unactivated carbon atom, but more slowly and with fewer turnovers. The carbon attacked is not the most chemically reactive, and the selectivity is determined by the geometry of the catalyst-substrate complex. Nonbinding substrates are not reactive under the conditions used, and substrates with more flexible binding geometries give more than a single product.

Euk-PLoc: an ensemble classifier for large-scale eukaryotic protein subcellular location prediction

With the avalanche of newly-found protein sequences emerging in the post genomic era, it is highly desirable to develop an automated method for fast and reliably identifying their subcellular locations because knowledge thus obtained can provide key clues for revealing their functions and understanding how they interact with each other in cellular networking. However, predicting subcellular location of eukaryotic proteins is a challenging problem, particularly when unknown query proteins do not have significant homology to proteins of known subcellular locations and when more locations need to be covered. To cope with the challenge, protein samples are formulated by hybridizing the information derived from the gene ontology database and amphiphilic pseudo amino acid composition. Based on such a representation, a novel ensemble hybridization classifier was developed by fusing many basic individual classifiers through a voting system. Each of these basic classifiers was engineered by the KNN (K-Nearest Neighbor) principle. As a demonstration, a new benchmark dataset was constructed that covers the following 18 localizations: (1) cell wall, (2) centriole, (3) chloroplast, (4) cyanelle, (5) cytoplasm, (6) cytoskeleton, (7) endoplasmic reticulum, (8) extracell, (9) Golgi apparatus, (10) hydrogenosome, (11) lysosome, (12) mitochondria, (13) nucleus, (14) peroxisome, (15) plasma membrane, (16) plastid, (17) spindle pole body, and (18) vacuole. To avoid the homology bias, none of the proteins included has > or =25% sequence identity to any other in a same subcellular location. The overall success rates thus obtained via the 5-fold and jackknife cross-validation tests were 81.6 and 80.3%, respectively, which were 40-50% higher than those performed by the other existing methods on the same strict dataset. The powerful predictor, named "Euk-PLoc", is available as a web-server at http://202.120.37.186/bioinf/euk . Furthermore, to support the need of people working in the relevant areas, a downloadable file will be provided at the same website to list the results predicted by Euk-PLoc for all eukaryotic protein entries (excluding fragments) in Swiss-Prot database that do not have subcellular location annotations or are annotated as being uncertain. The large-scale results will be updated twice a year to include the new entries of eukaryotic proteins and reflect the continuous development of Euk-PLoc.

Neural-targeted gene therapy for rodent and primate hemiparkinsonism

Expression of the rate-limiting enzyme for catecholamine biosynthesis, tyrosine hydroxylase (TH), via retroviral and plasmid expression vectors improved the efficacy of conditionally immortalized nigral neural cells in ameliorating rodent and nonhuman primate models of Parkinson's disease through neural transplantation. No improvement in rotational behavior occurred when sham transplants or nondopaminergic transplants were performed. Transplantation of the temperature-sensitive immortalized parental nigral neural line with a TH expression vector resulted in improvement for at least 2 months. Improvement was accompanied by HPLC evidence of increased L-DOPA production and immunocytochemical evidence of TH in the transfected cells increased over that of the parental line. No tumor formation was detected. These results suggest that: (1) temperature-sensitive immortalized neural cells may be genetically engineered successfully to improve their efficacy for the treatment of parkinsonism; and (2) a change in L-DOPA production, as opposed to growth factor production or other factors, is likely to account for the observed improvement, since the parental and derived lines differ by a single gene.

Direct electron transfer for hemoglobin in biomembrane-like dimyristoyl phosphatidylcholine films on pyrolytic graphite electrodes

Stable thin films made from dimyristoyl phosphatidylcholine (DMPC) with incorporated hemoglobin (Hb) on pyrolytic graphite (PG) electrodes were characterized by electrochemical and other techniques. Cyclic voltammetry (CV) of Hb-DMPC films showed a pair of well-defined and nearly reversible peaks at about -0.27 V vs. saturated calomel electrode (SCE) at pH 5.5, characteristic of Hb heme Fe(III)/Fe(II) redox couple. The electron transfer between Hb and PG electrodes was greatly facilitated in DMPC films. Apparent heterogeneous rate constants (ks) were estimated by fitting square wave voltammograms of Hb-DMPC films to a model featuring thin layer behavior and dispersion of formal potentials for redox center. The formal potential of Hb heme Fe(III)/Fe(II) couple in DMPC films shifted linearly between pH 4.5 to 11 with a slope of -48 mV pH-1, suggesting that one proton is coupled to each electron transfer in the electrochemical reaction. Soret absorption band positions suggest that Hb retains a near native conformation in DMPC films at medium pH. Differential scanning calorimetry (DSC) showed the phase transition for DMPC and Hb-DMPC films, suggesting DMPC has an ordered multibilayer structure. Trichloroacetic acid (TCA) was catalytically reduced by Hb-DMPC films with significant decreases in the electrode potential required.

LD78beta, a non-allelic variant of human MIP-1alpha (LD78alpha), has enhanced receptor interactions and potent HIV suppressive activity

Chemokines play diverse roles in inflammatory and non-inflammatory situations via activation of heptahelical G-protein-coupled receptors. Also, many chemokine receptors can act as cofactors for cellular entry of human immunodeficiency virus (HIV) in vitro. CCR5, a receptor for chemokines MIP-1alpha (LD78alpha), MIP-1beta, RANTES, and MCP2, is of particular importance in vivo as polymorphisms in this gene affect HIV infection and rate of progression to AIDS. Moreover, the CCR5 ligands can prevent HIV entry through this receptor and likely contribute to the control of HIV infection. Here we show that a non-allelic isoform of human MIP-1alpha (LD78alpha), termed LD78beta or MIP-1alphaP, has enhanced receptor binding affinities to CCR5 (approximately 6-fold) and the promiscuous beta-chemokine receptor, D6 (approximately 15-20-fold). We demonstrate that a proline residue at position 2 of MIP-1alphaP is responsible for this enhanced activity. Moreover, MIP-1alphaP is by far the most potent natural CCR5 agonist described to date, and importantly, displays markedly higher HIV1 suppressive activity than all other human MIP-1alpha isoforms examined. In addition, while RANTES has been described as the most potent inhibitor of CCR5-mediated HIV entry, MIP-1alphaP was as potent as, if not more potent than, RANTES in HIV-1 suppressive assays. This property suggests that MIP-1alphaP may be of importance in controlling viral spread in HIV-infected individuals.

Telomerized human microvasculature is functional in vivo

Previously we showed the superior in vitro survival of human telomerase reverse transcriptase (hTERT)-transduced human endothelial cells (EC). Here we show that retroviral-mediated transduction of hTERT in human dermal microvascular EC (HDMEC) results in cell lines that form microvascular structures when subcutaneously implanted in severe combined immunodeficiency (SCID) mice. Anti-human type IV collagen basement membrane immunoreactivity and visualization of enhanced green fluorescent protein (eGFP)-labeled microvessels confirmed the human origin of these capillaries. No human vasculature was observed after implantation of HT1080 fibrosarcoma cells, 293 human embryonic kidney cells, or human skin fibroblasts. Intravascular red fluorescent microspheres injected into host circulation were found within green "telomerized" microvessels, indicating functional murine-human vessel anastamoses. Whereas primary HDMEC-derived vessel density decreased with time, telomerized HDMEC maintained durable vessels six weeks after xenografting. Modulation of implant vessel density by exposure to different angiogenic and angiostatic factors demonstrated the utility of this system for the study of human microvascular remodeling in vivo.

N-acetylcysteine in combination with nitroglycerin and streptokinase for the treatment of evolving acute myocardial infarction. Safety and biochemical effects

BACKGROUND

N-acetylcysteine (NAC) has been shown to potentiate the effects of nitroglycerin (NTG) and to have antioxidant activity. This is the first study to assess the safety and effect of NAC in the treatment of evolving acute myocardial infarction (AMI).

METHODS AND RESULTS

Patients with AMI received either 15 g NAC infused over 24 hours (n = 20) or no NAC (n = 7), combined with intravenous NTG and streptokinase. Peripheral venous plasma malondialdehyde (MDA), reduced (GSH) and oxidized (GSSG) glutathione concentrations, and rate of reperfusion (using continuous ST-segment analysis) were measured. Cardiac catheterization was performed between days 2 and 5. No significant adverse events occurred. Less oxidative stress occurred in patients treated with NAC than in patients not receiving NAC (GSH to GSSG ratio 44 +/- 25 versus 19 +/- 13 at 4 hours, P < .05). NAC concentration (mean 172 +/- 79 mumol/L at 4 hours) was correlated to GSH concentration (P = .006). MDA concentrations were lower (P = .001) over the first 8 hours of treatment with NAC. There was a trend toward more rapid reperfusion (median 58 minutes, 95% confidence interval [CI] 48 to 98 minutes versus median 95 minutes, 95% CI 59 to 106 minutes; P = .17) and better preservation of left ventricular function (cardiac index 3.4 +/- 0.8 versus 2.6 +/- 0.27 L.min.m2, P = .009) with NAC treatment.

CONCLUSIONS

NAC in combination with NTG and streptokinase appeared to be safe for the treatment of evolving AMI and was associated with significantly less oxidative stress, a trend toward more rapid reperfusion, and better preservation of left ventricular function.

Characterization of the binding and chiral separation of D- and L-tryptophan on a high-performance immobilized human serum albumin column

High-performance affinity chromatography was used to study the separation and binding of D- and L-tryptophan on an immobilized human serum albumin (HSA) column. Frontal analysis and zonal elution studies indicated that both D- and L-tryptophan were binding to single but distinct sites on HSA. L-Tryptophan bound to the indole site of HSA. D-Tryptophan had indirect interactions with the warfarin site of HSA but no interactions with the indole site. The association constants for the binding of D- and L-tryptophan at pH 7.4 and 25 degrees C were 0.4 x 10(4) and 2.7 x 10(4) M-1, respectively. The value of delta G for these sites ranged from -5.2 to -5.7 kcal/mol (1 cal = 4.184 J) and had a significant entropy component. The effects of varying the pH, phosphate concentration, temperature and polarity of the mobile phase on the binding of D- and L-tryptophan to HSA were examined. The role of sample size in determining peak shape and retention was also considered. From these data, general guidelines were developed for the separation of D- and L-tryptophan on immobilized HSA. Under optimized conditions the enantiomers were separated in less than 2 min with baseline resolution.

Phytoestrogens from Psoralea corylifolia reveal estrogen receptor-subtype selectivity

The seed of Psoralea corylifolia L. (PCL), a well-known traditional Chinese medicine, has been applied as a tonic or an aphrodisiac agent and commonly used as a remedy for bone fracture, osteomalacia and osteoporosis in China. In our study, the estrogen receptor subtype-selective activities of the extracts and compounds derived from PCL were analyzed using the HeLa cell assay. The different fractions including petroleum ether, CH(2)Cl(2) and EtOAc fractions of the EtOH extract of PCL showed significant activity in activating either ERalpha or ERbeta whereas the n-BuOH fraction showed no estrogenic activity. Further chromatographic purification of the active fractions yielded seven compounds including the two coumarins isopsoralen and psoralen, the four flavonoids isobavachalcone, bavachin, corylifol A and neobavaisoflavone, and the meroterpene phenol, bakuchiol. In reporter gene assay, the two coumarins (10(-8)-10(-5)M) acted as ERalpha-selective agonists while the other compounds (10(-9)-10(-6)M) activated both ERalpha and ERbeta. The estrogenic activities of all compounds could be completely suppressed by the pure estrogen antagonist, ICI 182,780, suggesting that the compounds exert their activities through ER. Only psoralen and isopsoralen as ERalpha agonists promoted MCF-7 cell proliferation significantly. Although all the compounds have estrogenic activity, they may exert different biological effects. In conclusion, both ER subtype-selective and nonselective activities in compounds derived from PCL suggested that PCL could be a new source for selective estrogen-receptor modulators.

The structure of Ascaris hemoglobin domain I at 2.2 A resolution: molecular features of oxygen avidity

The perienteric hemoglobin of the parasitic nematode Ascaris has an exceptionally high affinity for oxygen. It is an octameric protein containing two similar heme-binding domains per subunit, but recombinant constructs expressing a single, monomeric heme-binding domain (domain 1; D1) retain full oxygen avidity. We have solved the crystal structure of D1 at 2.2 A resolution. Analysis of the structure reveals a characteristic globin fold and illuminates molecular features involved in oxygen avidity of Ascaris perienteric hemoglobin. A strong hydrogen bond between tyrosine at position 10 in the B helix (tyrosine-B10) and the distal oxygen of the ligand, combined with a weak hydrogen bond between glutamine-E7 and the proximal oxygen, grips the ligand in the binding pocket. A third hydrogen bond between these two amino acids appears to stabilize the structure. The B helix of D1 is displaced laterally by 2.5 A when compared with sperm whale myoglobin. This shifts the tyrosine-B10 hydroxyl far enough from liganded oxygen to form a strong hydrogen bond without steric hindrance. Changes in the F helix compared with myoglobin contribute to a tilted heme that may also be important for oxygen affinity.

Probing ion permeation and gating in a K+ channel with backbone mutations in the selectivity filter

Potassium channels selectively conduct K+ ions across cell membranes, and use diverse mechanisms to control their gating. We studied ion permeation and gating of an inwardly rectifying K+ channel by individually changing the amide carbonyls of two conserved glycines lining the selectivity filter to ester carbonyls using nonsense suppression. Surprisingly, these backbone mutations do not significantly alter ion selectivity. However, they dramatically change the kinetics of single-channel gating and produce distinct subconductance levels. The mutation at the glycine closer to the inner mouth of the pore also abolishes high-affinity binding of Ba2+ to the channel, indicating the importance of this position in ion stabilization in the selectivity filter. Our results demonstrate that K+ ion selectivity can be retained even with significant reduction of electronegativity in the selectivity filter, and that conformational changes of the filter arising from interactions between permeant ions and the backbone carbonyls contribute directly to channel gating.