Diffuse pollution monitoring and modelling of small urban watershed in Brazil Cerrado.

The stormwater runoff carries different pollutants that can reduce the quality of receiving waters due to diffuse pollutant loads. This research was aimed at evaluating the concentration of pollutants in stormwater and the application of SWMM (Storm Water Management Model) to an urban catchment in Lake Paranoá watershed to carry out the simulation of flow discharge with the hydraulic model, and subsequently to estimate the loads conveyed to the lake in ordinary events of precipitation. This study was carried out based on rainfall and runoff monitoring during events. It was confirmed that this model's results fit well in simulation of this type of watershed, leading to high value of the Nash-Sutcliffe coefficient after calibration but, as expected, precipitation distribution is a very important factor for calibration. Concerning water quality, it was observed that the event mean concentration values of suspended solids and chemical oxygen demand were high, indicating that the diffuse pollution is an important source of pollution of the receiving waters. The monitoring and modelling of stormwater are essential to identify diffuse pollution discharge, in searching for a sustainable solution.

Monobody adapter for functional antibody display on nanoparticles for adaptable targeted delivery applications.

Vascular endothelial cells (ECs) play a central role in the pathophysiology of many diseases. The use of targeted nanoparticles (NPs) to deliver therapeutics to ECs could dramatically improve efficacy by providing elevated and sustained intracellular drug levels. However, achieving sufficient levels of NP targeting in human settings remains elusive. Here, we overcome this barrier by engineering a monobody adapter that presents antibodies on the NP surface in a manner that fully preserves their antigen-binding function. This system improves targeting efficacy in cultured ECs under flow by >1000-fold over conventional antibody immobilization using amine coupling and enables robust delivery of NPs to the ECs of human kidneys undergoing ex vivo perfusion, a clinical setting used for organ transplant. Our monobody adapter also enables a simple plug-and-play capacity that facilitates the evaluation of a diverse array of targeted NPs. This technology has the potential to simplify and possibly accelerate both the development and clinical translation of EC-targeted nanomedicines.

Induction of interleukin 1 alpha mRNA during the antigen-dependent interaction of sensitized T lymphoblasts with macrophages.

DNA-RNA hybridization with an IL-1 alpha cDNA probe was used to monitor the induction of IL-1 in macrophages that were acting as accessory cells for the proliferation of T lymphocytes. Mouse peritoneal macrophages bound and stimulated T lymphocytes in the presence of the mitogens, Con A, or anti-CD3 mAb, but little or no IL-1 mRNA was detectable. In contrast, if the T cells were first sensitized in a mixed leukocyte reaction with dendritic cells and then added to macrophages, IL-1 mRNA was clearly induced. Induction of the IL-1 alpha gene seemed to require the recognition of class II MHC products on the macrophage because of the following observations: specific rather than third-party macrophages were responsive to the T blast but not to T cell-conditioned media; induction was blocked by an anti-Ia mAb; CD4+ rather than CD8+ blasts were active; and polyclonal Con A blasts were much less efficient than antigen-specific T cells. Our data indicate that the strongest signal for IL-1 production during the macrophage-T cell interaction occurs in the efferent limb of the response, after rather than before the formation of class II MHC-restricted T lymphoblasts.

Interleukin 1 enhances T-dependent immune responses by amplifying the function of dendritic cells.

The function of exogenous murine recombinant IL-1 alpha as a T lymphocyte-activating molecule was examined. IL-1 did not induce IL-2 release or responsiveness in purified T cells regardless of their state of activation: unprimed lymphocytes, freshly sensitized lymphocytes, or memory cells derived from the blasts. Nor did IL-1 synergize with mitogens, or with antigens, to stimulate proliferation. For example the combinations of IL-1 plus Ia+ peritoneal macrophages, or IL-1 plus Con A, were less than 5% as effective in triggering T cell growth as a low dose (1%) of dendritic cells. However, when IL-1 was added at the onset of culture, the response to limiting doses of dendritic cells was increased 3- to 10-fold in several systems: the syngeneic and allogeneic MLR, Con A- and periodate-induced polyclonal mitogenesis, and T-dependent antibody formation against foreign red cells. The amplifying effect of IL-1 could be obtained if the dendritic cells but not the responding lymphocytes were exposed to IL-1 before use as accessory cells. Optimal activation of dendritic cells required a dose of 5 U/ml (50 pM) and 18 h of exposure, and was not due to carryover of IL-1 into the lymphocyte culture. IL-2, IL-3, and cachectin/TNF did not amplify dendritic cell function, while IFN-gamma diminished it. The enhanced function of IL-1-treated dendritic cells was due to an enhanced clustering with helper T lymphocytes in the first day of the MLR response. Therefore IL-1 does not seem to act as an activating factor for most peripheral T lymphocytes. Instead, IL-1 enhances the function of accessory dendritic cells and represents the first molecule that has been shown to enhance the immune response at this critical level.

Presentation of exogenous protein antigens by dendritic cells to T cell clones. Intact protein is presented best by immature, epidermal Langerhans cells.

The capacity of dendritic cells to present protein antigens has been studied with two MHC class II-restricted, myoglobin-specific, T cell clones. Spleen dendritic cells and cultured epidermal Langerhans cells (LC) presented native myoglobin weakly and often not at all. These same populations were powerful stimulators of allogeneic T cells in the primary MLR. Freshly isolated LC were in contrast very active in presenting proteins to T cell clones but were weak stimulators of the MLR. Both fresh and cultured LC could present specific peptide fragments of myoglobin to the clones. These results suggest that dendritic cells in nonlymphoid tissues like skin can act as sentinels for presenting antigens in situ, their accessory function developing in two phases. First antigens are captured and appropriately presented. Further handling of antigen then is downregulated while the cells acquire strong sensitizing activity for the growth and function of resting T lymphocytes. The potent MLR stimulating activity of cultured epidermal LC and lymphoid dendritic cells probably reflects prior handling of antigens leading to the formation of allogeneic MHC-peptide complexes.

Specific antimononuclear phagocyte monoclonal antibodies. Application to the purification of dendritic cells and the tissue localization of macrophages.

3C10 and 1D9 are two related monoclonal antibodies that specifically identify human mononuclear phagocytes in a large number of sites, including blood monocytes, alveolar macrophages, and macrophages in tissue sections of spleen, lymph node, and skin. The antigen persists on monocytes cultured for greater than 4 wk, but it is not found on giant cells. The 3C10-1D9 determinant is carried by a 55 kD polypeptide, is expressed at approximately 40,000 copies per monocyte, and is protease sensitive. The antigen is clearly different from HLA-class II or Ia-like antigens that have been studied with a new monoclonal 9.3F10. The 9.3F10 antigen is found on B cells, dendritic cells and monocytes; is protease resistant, and occurs on a 33-29 kD doublet typical of class II products. The 3C10 monoclonal provides a clear distinction between human mononuclear phagocytes and dendritic cells. First, monocytes and lymphocytes can be eliminated from plastic-adherent mononuclear cells using 3C10, complement, and two previously described cytotoxic antibodies, BA-1 (anti-B cell) and Leu-1 (anti-T cell). As a result, the trace dendritic cell component of blood can be enriched to considerable purity (65-75%) and yield. Second, immunocytochemical staining of tissue sections reveals that 3C10+ macrophages are anatomically segregated from dendritic cells. Large numbers of 3C10+ cells are found in red pulp of spleen and in regions surrounding lymphatic channels of lymph node. However, 3C10+ macrophages are scarce in white pulp of spleen and the lymphocyte-rich cortex of node that are the sites where dendritic cells are localized. 3C10+ cells in skin are found in the dermis, particularly in leprosy infiltrates, but the Langerhans' cells of epidermis are 3C10-. The distinctive localization of macrophages and dendritic cells is consistent with their respective functions as effector and accessory cells in the immune response.

GC-1 mRHBDD1 knockdown spermatogonia cells lose their spermatogenic capacity in mouse seminiferous tubules.

BACKGROUND: Apoptosis is important for regulating spermatogenesis. The protein mRHBDD1 (mouse homolog of human RHBDD1)/rRHBDD1 (rat homolog of human RHBDD1) is highly expressed in the testis and is involved in apoptosis of spermatogonia. GC-1, a spermatogonia cell line, has the capacity to differentiate into spermatids within the seminiferous tubules. We constructed mRHBDD1 knockdown GC-1 cells and evaluated their capacity to differentiate into spermatids in mouse seminiferous tubules. RESULTS: Stable mRHBDD1 knockdown GC-1 cells were sensitive to apoptotic stimuli, PS341 and UV irradiation. In vitro, they survived and proliferated normally. However, they lost the ability to survive and differentiate in mouse seminiferous tubules. CONCLUSION: Our findings suggest that mRHBDD1 may be associated with mammalian spermatogenesis.

Magnetohydrodynamic production of relativistic jets.

A number of astronomical systems have been discovered that generate collimated flows of plasma with velocities close to the speed of light. In all cases, the central object is probably a neutron star or black hole and is either accreting material from other stars or is in the initial violent stages of formation. Supercomputer simulations of the production of relativistic jets have been based on a magnetohydrodynamic model, in which differential rotation in the system creates a magnetic coil that simultaneously expels and pinches some of the infalling material. The model may explain the basic features of observed jets, including their speed and amount of collimation, and some of the details in the behavior and statistics of different jet-producing sources.

A novel member of the Rhomboid family, RHBDD1, regulates BIK-mediated apoptosis.

Rhomboid family members are widely conserved and found in all three kingdoms of life. They are serine proteases and serve important regulatory functions. In the present study, a novel gene highly expressed in the testis, RHBDD1, is shown to be a new member of the Rhomboid family, participating in the cleavage of BIK, a proapoptotic member of the Bcl-2 family. The RHBDD1-involved proteolytic modification is upstream of the BIK protein degradation pathway. Mutagenesis studies show that the amino acid residues glycine142 and serine144 of RHBDD1 are crucial for its activity in cleaving BIK at a site located in the transmembrane region. Overexpression or knock-down of RHBDD1 in HEK 293T cells can reduce or enhance BIK-mediated apoptosis, respectively. The present findings suggest that, by acting as a serine protease, RHBDD1 modulates BIK-mediated apoptotic activity.

Identification of WSB1 gene as an important regulator in the development of zebrafish embryo during midblastula transition.

To uncover novel genes potentially involved in embryo development, especially at the midblastula transition (MBT) phase in the developing embryo of zebrafish, Affymetrix zebrafish GeneChip microarray analysis was carried out on the expression of 14,900 gene transcripts. The results of the analysis showed that 360 genes were clearly up-regulated and 119 genes were markedly down-regulated. Many of these genes were involved in transcription factor activity, nucleic acid binding, and cell growth. The present study showed that significant changes in transcript abundance occurred during the MBT phase. The expression of eight of these 479 genes was identified by reverse transcription-polymerase chain reaction analysis, confirming the microarray results. The WSB1 gene, found to be down-regulated by the microarray and reverse transcription-polymerase chain reaction analyses, was selected for further study. Sequence analysis of the WSB1 gene showed that it encodes a protein with 75% identity to the corresponding active human orthologs. In addition, WSB1 gene expression was detected at a higher level at 2 h post fertilization and at a lower level at 4 h post fertilization, consistent with the chip results. Overexpression of the WSB1 gene can result in the formation of abnormalities in embryos, as determined by fluorescence-activated cell sorting. The present study showed unequivocally that the occurrence of WSB1 expression is an important event during the MBT phase in the development of zebrafish embryos.

Development of a micro-planar amperometric bile acid biosensor for urinalysis.

The determination of bile acid concentration in urine is useful for the screening and diagnosis of various hepatobiliary diseases. Currently, there is no concise method to determine bile acid concentration in urine. This study describes a bile acid biosensor fabricated by electrochemical technique for urinalysis. The micro-planar electrodes employed for the study consisted of a working electrode (platinum), a counter electrode (platinum) and a reference electrode (silver/silver chloride (Ag/AgCl)). The sensor chip was coated with Nafion using a spin-coater in order to both eliminate many interference species in urine and achieve long-term stability of the reference electrode. Nafion coating allowed the sensor chip to prevent the electrode reaction from interference species in urine, because it is charged negative strongly (Nafion contains sulfonic acid group). Three enzymes (bile acid sulfate sulfatase: BSS, beta-hydroxysteroid dehydrogenase: beta-HSD, and NADH oxidase: NHO) were immobilized by glutaraldehyde (GA: cross-linker) onto the sensor chip, because the immobilization of enzymes by GA is simple and commonly carried out. The sensor chip was able to detect bile acid in buffer solution. The optimum enzyme ratio immobilized onto the sensor chip was BSS:beta-HSD:NHO=4:4:20 U/1 chip. There was a relationship between the concentration of bile acid and the response current value. The dynamic range of the sensor chip was 2-100 microM for bile acid. Additionally, bile acid in the urine specimen could be detected using this bile acid biosensor. We present a simple and rapid bile acid biosensor with high sensitivity and high reproducibility.

Impact of combinatorial dysfunctions of Tet2 and Ezh2 on the epigenome in the pathogenesis of myelodysplastic syndrome.

Somatic inactivating mutations in epigenetic regulators are frequently found in combination in myelodysplastic syndrome (MDS). However, the mechanisms by which combinatory mutations in epigenetic regulators promote the development of MDS remain unknown. Here we performed epigenomic profiling of hematopoietic progenitors in MDS mice hypomorphic for Tet2 following the loss of the polycomb-group gene Ezh2 (Tet2KD/KDEzh2Δ/Δ). Aberrant DNA methylation propagated in a sequential manner from a Tet2-insufficient state to advanced MDS with deletion of Ezh2. Hyper-differentially methylated regions (hyper-DMRs) in Tet2KD/KDEzh2Δ/Δ MDS hematopoietic stem/progenitor cells were largely distinct from those in each single mutant and correlated with transcriptional repression. Although Tet2 hypomorph was responsible for enhancer hypermethylation, the loss of Ezh2 induced hyper-DMRs that were enriched for CpG islands of polycomb targets. Notably, Ezh2 targets largely lost the H3K27me3 mark while acquiring a significantly higher level of DNA methylation than Ezh1 targets that retained the mark. These findings indicate that Ezh2 targets are the major targets of the epigenetic switch in MDS with Ezh2 insufficiency. Our results provide a detailed trail for the epigenetic drift in a well-defined MDS model and demonstrate that the combined dysfunction of epigenetic regulators cooperatively remodels the epigenome in the pathogenesis of MDS.

A sperm component, HSD-3.8 (SPAG1), interacts with G-protein beta 1 subunit and activates extracellular signal-regulated kinases (ERK).

HSD-3.8 cDNA (accession number AF311312) encodes a human sperm component. A 0.7 kb fragment (HSD-0.7) containing three immunological epitopes of HSD-3.8 cDNA was prepared and expressed in E. coli. Immunization of female rats with the recombinant HSD-0.7 proteins induced infertility. A cDNA fragment encoding the C-terminal 144 amino acids of human G-protein beta l subunit (Gbeta1-C144) was screened by yeast two-hybrid, when HSD-0.7 segment was used as a bait. Recombinant His6-tagged-Gbeta1-C144 protein was expressed in E. coli BL21 and Anti-Gbeta1 serum was raised with purified Gbeta1-C144. HA-tagged HSD-0.7 and FLAG-tagged Gbeta1 plasmids were constructed and co-transfected into human embryonal kidney 293 cells. Two proteins were localized at superimposable sites in the cytoplasm, and they formed a complex when 500 micromol/L GDP existed. Overexpression of HSD-0.7 activated the G-protein-mediated extracellular signal-regulated kinases (ERK1/2); however, the truncated fragments of HSD-0.7, which lacked either TPR domain or P-loop, lost the ability to activate the ERK1/2 pathway. Further study revealed that the activation of ERK1/2 was protein kinase C (PKC) rather than Ras dependent. These results provide evidence that HSD-3.8 present in spermatocytes and sperm may participate in spermatogenesis and fertilization process by activating the PKC-dependent ERK1/2 signal transduction pathway.

Expression of alpha-1,3-fucosyltransferase type IV and VII genes is related to poor prognosis in lung cancer.

To date, five alpha-1,3-fucosyltransferase genes (Fuc-TIII, IV, V, VI, and VII) have been cloned. To examine the role of alpha-1,3-fucosyltransferase in the synthesis of sialyl Lewis x and the prognosis of lung cancer, PCR amplification of five fucosyltransferase genes and immunohistochemical staining of sialyl Lewis x were performed in 333 patients with lung cancer who underwent surgical resection from 1980 to 1993. The frequencies of Fuc-TIII/V, Fuc-TVI, Fuc-TIV, and Fuc-TVII expression were 9%, 26%, 75%, and 66%, respectively. The frequency of sialyl Lewis x expression (75%) was comparable to Fuc-TIV and Fuc-TVII expression. However, the grading of sialyl Lewis x staining correlated only with the grading of Fuc-TVII gene amplification. Survival of the patients whose tumors showed strong expression of Fuc-TIV and/or FucT-VII was significantly shorter than that of the patients whose tumors did not express either Fuc-TIV or Fuc-TVII. These results suggest that Fuc-TIV and Fuc-TVII expression may be of prognostic value among patients with lung cancer by participating in the biosynthesis of sialyl Lewis x.

Kidney Transplantation, Cardiovascular Risk, and Long-Term Dialysis in Japan.

BACKGROUND: The waiting time for deceased-donor kidney-only transplantations in Japan is long. Herein, we assessed the effect of length of dialysis on the outcomes of these patients. METHODS: We divided patients into 2 groups based on length of dialysis (Group A, <15 years, and Group B, ≥15 years), and compared the background and outcomes after kidney transplantation. RESULTS: Group A included 210 patients and Group B included 35 patients. In Group B, 20% of transplants were from living donors. Patient age (P = .017) and the hepatitis C infection rate (P = .018) were significantly higher in Group B, whereas hypertension (P = .011), diabetes (P = .041), and ABO-incompatibility rates (P = .015) were significantly higher in Group A. The 5- and 10-year survival rates were 97.0% and 95.4%, respectively, in Group A and 97.1% and 97.1%, respectively, in Group B. The 5- and 10-year graft survival rates were 95.4% and 84.8%, respectively, in Group A and 97.1% and 73.1%, respectively, in Group B. There were no significant differences between the groups in patient survival (P = .74) and graft survival (P = .72). The 5- and 10-year cardiovascular event-free survival rates were 95.9% and 92.4%, respectively, in Group A and 88.6% and 76.8%, respectively, in Group B. Cardiovascular event-free survival was significantly higher in Group A (P = .038). Cox stepwise multivariate analysis indicated that length of dialysis was a significant predictor of cardiovascular events (hazard risk, 1.007; range, 1.001-1.012; P = .012). CONCLUSION: The prognosis after kidney transplantation is promising even after a long length of dialysis, although evaluation of the cardiovascular risk is needed in these cases.

Assignment of chromosomal locus and evidence for alternatively spliced mRNAs of a human sperm membrane protein (hSMP-1).

The gene (HSD-1) coding a human sperm membrane protein (hSMP-1) was isolated from a human testis cDNA expression library using antibodies found in the serum of an infertile woman. HSD-1 was localized to a single locus on chromosome 9 and assigned to band 9p12-p13 by fluorescent in situ hybridization (FISH) mapping and DAPI (4,6-diamidino-2-phenylindole) banding, using rat/human somatic cell hybrids and metaphase chromosomes of human lymphocytes. In rescreening a testis lambdagt10 cDNA expression library, the full-length cDNA (HSD-1) and several truncated cDNAs with heterologous regions were isolated from positive clones. The heterology consisted of deletion, insertion and alteration of the 5'-end. These heterologous truncated fragments may be produced by alternative splicing of mRNAs. Two recombinant prokaryotic expression vectors were constructed with one of the heterologous fragment (clone #26) with and without the alternative 5'-end. Escherichia coli transfected with the construct containing the alternative 5'-end failed to produce the recombinant product, whereas those transfected with the vector lacking the 5'-end produced hSMP-1. DNASIS analysis of the structure of #26 mRNA suggests that the 5'-end has a stable secondary configuration that may maintain the mRNA in an inactivated state, whereby hindering its translation and preventing the expression of the gene.

beta-Microseminoprotein/prostatic secretory protein is a member of immunoglobulin binding factor family.

Human seminal plasma contains a factor that binds human IgG, designated as immunoglobulin binding factor (IgBF). Under reducing condition IgBF interacts with anti-Leu-11b, a murine monoclonal antibody raised against human FcgammaRIII/CD16. IgBF shows no binding activity under non-reducing condition. Three components having IgBF activity were separated by HPLC and their amino acid sequences determined. The main IgBF showed structural identity to beta-microseminoprotein (beta-MSP), prostatic secretory protein of 94 amino acids (PSP94) and beta-inhibin. The slight variation in the reported sequences of these proteins has been attributed to analytical error. In the present study the molecular masses of main IgBF and beta-MSP/PSP94 were found to be identical by mass spectrometry. In addition, a large component of IgBF and a shorter beta-MSP consisting of 93 amino acids were identified. The binding of beta-MSP for human IgG and anti-Leu-11b antibody is demonstrable only under reducing condition, determined by Western blot analysis. The present data clearly show that IgBF is a family composed of at least three isoforms. One of the members is beta-MSP/PSP94. This family should be designated as IgBF.

Remnant lipoproteins induce proatherothrombogenic molecules in endothelial cells through a redox-sensitive mechanism.

BACKGROUND: Triglyceride-rich lipoproteins (TGLs) are atherogenic. However, their cellular mechanisms remain largely unexplained. This study examined the effects of isolated remnant-like lipoprotein particles (RLPs) on the expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and tissue factor (TF), proatherothrombogenic molecules, in cultured human endothelial cells. METHODS AND RESULTS: RLPs were isolated from plasma of hypertriglyceridemic patients by use of the immunoaffinity gel mixture of anti-apoA-1 and anti-apoB-100 monoclonal antibodies. The incubation of cells with RLPs significantly upregulated mRNA and protein expression of these molecules. Total TGLs (d<1.006) and LDL had fewer or minimal effects on expression of these molecules compared with RLPs. RLPs increased intracellular oxidant levels, as assessed with an oxidant-sensitive probe. Combined incubation with alpha-tocopherol or N-acetylcysteine, both antioxidants, suppressed RLP-induced increase in expression of these molecules. In patients with higher plasma levels of RLPs, plasma levels of soluble forms of ICAM-1 and VCAM-1 were significantly higher than in patients with lower RLP levels. Treatment with alpha-tocopherol for 1 month decreased levels of the soluble adhesion molecules concomitantly with an increase in resistance of RLPs to oxidative modification in patients with high RLP levels. CONCLUSIONS: RLPs upregulated endothelial expression of ICAM-1, VCAM-1, and TF, proatherothrombogenic molecules, partly through a redox-sensitive mechanism. RLPs may have an important role in atherothrombotic complications in hypertriglyceridemic patients.

Identification and characterization of a novel splice variant of beta3 subunit of GABA(A) receptor in rat testis and spermatozoa.

Gamma-aminobutyric acid type A (GABA(A)) receptors are the major sites of inhibitory action of fast synaptic neurotransmission in the brain. Their receptors are also widely distributed in peripheral and endocrine tissues. A full-length cDNA encoding a novel splice variant of beta3 subunit of GABA(A) receptor, designated as beta3t, was identified in rat testis. This isoform contains a segment, having identical amino acid sequence as the beta3 subunit of neuronal GABA(A) receptors except for a section composed of 25 different amino acid sequence in the N-terminus. Northern blot shows that this isoform is found in rat testis. The beta3t isoform mRNA was detected in germ cells in the late step of spermatogenesis by in situ hybridization assay. Results of immunohistochemical and immunocytochemical assays indicate that the beta3t isoform is expressed in rat testis and spermatozoa. To determine a possible function of the N-terminal 25 amino acid segment, a recombinant plasmid of beta3t-EGFPC was constructed by fusing green fluorescent protein to the C-terminus of the beta3t isoform. The chimera product failed to be translocated unto the cell surface when expressed in HEK 293 cells; whereas, the beta3 subunit of rat brain is incorporated into the plasma membrane. In conclusion, the present results show that one variant of beta3 subunit of GABA(A) receptor, designated as beta3t, is found in germ cells of rat testis and sperm. The inability of the beta3t variant to target into the plasma membrane maybe a consequence of the unique 25 amino acid segment in the N-terminus.

Solution conformation and amyloid-like fibril formation of a polar peptide derived from a beta-hairpin in the OspA single-layer beta-sheet.

A 23-residue peptide termed BH(9-10) was designed based on a beta-hairpin segment of the single-layer beta-sheet region of Borrelia OspA protein. The peptide contains a large number of charged amino acid residues, and it does not follow the amphipathic pattern that is commonly found in natural beta-sheets. In aqueous solution, the peptide was highly soluble and flexible, with a propensity to form a non-native beta-turn. Trifluoroethanol (TFE) stabilized a native-like beta-turn in BH(9-10). TFE also decreased the level of solubility of the peptide, resulting in peptide precipitation. The precipitation process accompanied a conformational conversion to a beta-sheet structure, as judged with circular dichroism spectroscopy. The precipitate was found to be fibrils similar to those associated with human amyloid diseases. The fibrillization kinetics depended on peptide and TFE concentrations, and had a nucleation step followed by an assembly step. The fibrillization was reversible, and the dissociation reaction involved two phases. TFE appears to induce the fibrils by stabilizing a beta-sheet conformation of the peptide that optimally satisfies hydrogen bonding and electrostatic complementarity. This TFE-induced fibrillization is quite unusual, because most amyloidogenic peptides form fibrils in aqueous solution and TFE disrupts these fibrils. Nevertheless, the BH(9-10) fibrils have similar structure to other fibrils, supporting the emerging idea that polypeptides possess an intrinsic ability to form amyloid-like fibrils. The high level of solubility of BH(9-10), the ability to precisely control fibril formation and dissociation, and the high-resolution structure of the same sequence in the beta-hairpin conformation in the OspA protein provide a tractable experimental system for studying the fibril formation mechanism.