Towards hard-magnetic behavior of CoFe2O4 nanoparticles: a detailed study of crystalline and electronic structures, and magnetic properties

We have used the coprecipitation and mechanical-milling methods to fabricate CoFe₂O₄ nanoparticles with an average crystallite size (d) varying from 81 to ∼12 nm when changing the milling time (t _m) up to 180 min. X-ray diffraction and Raman-scattering studies have proved the samples crystalizing in the spinel structure. Both the lattice constant and residual strain tend to increase when t _m(d) increases (decreases). The analysis of magnetization data has revealed a change in the coercivity (H _c) towards the hard-magnetic properties. Specifically, the maximum H _c is about 2.2 kOe when t _m = 10 min corresponding to d ≈ 29 nm; beyond this t _m(d) value, H _c gradually decreases. Meanwhile, the increase of t _m always reduces the saturation magnetization (M _s) from ∼69 emu g^-1 for t _m = 0 to 35 emu g^-1 for t _m = 180 min. The results collected as analyzing X-ray absorption data have indicated a mixed valence state of Fe^2+,3+ and Co²⁺ ions. We think that the migration and redistribution of these cations between the tetrahedral and octahedral sites together with lattice distortions and defects induced by the milling process have impacted the magnetic properties of the CoFe₂O₄ nanoparticles.

Host Transcriptome Analysis of Ferret Tissues Following Henipavirus Infection

Ferrets are commonly used as experimental models of infection for a variety of viruses due to their susceptibility to human respiratory viruses and the close resemblance of pathological outcomes found in human infections. Even though ferret-specific reagents are limited, the use of ferrets as a preclinical experimental model of infection has gained considerable interest since the publication of the ferret transcriptome and draft ferret genome. These advances have made it feasible to easily perform whole-genome gene expression analysis in the ferret infection model. Here, we describe methods for genome-wide gene expression analysis using RNA sequence (RNAseq) data obtained from the lung and brain tissues obtained from experimental infections of Hendra (HeV) and Nipah (NiV) viruses in ferrets. We provide detailed methods for RNAseq and representative data for host gene expression profiles of the lung tissues that show early activation of interferon pathways and later activation of inflammation-related pathways.

Strong correlation between flux pinning and epitaxial strain in the GdBa2Cu3O7-x /La0.7Sr0.3MnO3 nanocrystalline heterostructure

The effect of magnetic flux pinning is investigated in GdBa₂Cu₃O₇ (GdBCO) thin films with two different types of ferromagnetic La_0.7Sr_0.3MnO₃ (LSMO) buffers (nanoparticles and a layer) deposited on an STO substrate. Magnetization analyses reveal the presence of multiple flux pinning mechanisms responsible for the improvement in the critical current density of GdBCO films. While core pinning becomes a dominant pinning mechanism in GdBCO films with LSMO nanoparticles, a hybrid effect of magnetic-volume and core-point pinning is observed in GdBCO films with LSMO layers. Examinations of local structures for both LSMO and GdBCO using extended X-ray absorption fine structure spectroscopy (EXAFS) exhibit a close relation between the parameters in the pinning force scaling and the length ratio of the Mn–O bond to the Cu–O bond. This result implies that the origin of core pinning is probably attributed to epitaxial strain induced by lattice mismatch between LSMO and GdBCO. Therefore, an appropriate strain state of LSMO is required for an effective operation of magnetic pinning.

The effect of magnetic flux pinning is investigated in GdBa₂Cu₃O₇ (GdBCO) thin films with two different types of ferromagnetic La_0.7Sr_0.3MnO₃ (LSMO) buffers (nanoparticles and a layer) deposited on an STO substrate.

Modulation of rumen fermentation and microbial community through increasing dietary cation-anion difference in Chinese Holstein dairy cows under heat stress conditions

AIMS

The effect of increasing dietary cation-anion difference (DCAD) on rumen fermentation and ruminal microbial community in dairy cows under heat stress (HS) conditions were evaluated.

METHODS AND RESULTS

This study was performed as a two-period cross-over design during the summer season, with eight lactating dairy cows randomly distributed to either a control DCAD diet (CON: 33·5 mEq/100 g DM) or high DCAD diet (HDCAD: 50·8 mEq/100 g DM). Throughout the present study, the temperature and humidity index (THI; 80·2 ± 4·29) was generally elevated above the threshold (THI = 72) that is reported to cause HS in lactating dairy cows. Rumen liquid samples were collected on 15 and 21 d during each 21 d-period. The absolute concentration of ruminal total volatile fatty acid (TVFA) in HDCAD treatment was significantly (P < 0·05) higher than those in the control, whilst the ruminal pH, NH₃ -N, and VFA molar percentages were unaffected through increasing DCAD. Furthermore, the copy numbers of the cellulolytic bacteria Ruminococcus albus and Ruminococcus flavefaciens in rumen fluid significantly (P < 0·05) rose along with the increment of DCAD. Although the Alpha diversity indexes and the bacterial microbiota structure were unaffected, increasing DCAD significantly (P < 0·05) enriched the phylum Fibrobacteres and genus Fibrobacter in the microflora of rumen fluid, whilst the genera Flexilinea and Dubosiella were the most differentially abundant taxa in the control.

CONCLUSIONS

Increasing DCAD under HS conditions resulted in a greater concentration of total VFA without affecting rumen bacteria diversity or structure, although the enrichment of some cellulolytic/hemicellulolytic bacteria was observed.

SIGNIFICANCE AND IMPACT OF THE STUDY

The present study provides information on the modulation of rumen fermentation and microbial community through the increment of DCAD in Holstein dairy cows under HS conditions.

Abstract P5-16-18: Oncologic outcomes and reconstruction quality of immediate autologous breast reconstruction in intermediate and locally advanced breast cancer

Purpose: We analyzed oncologic outcomes and reconstruction quality in locally advanced stage breast cancer after performing immediate autologous breast reconstruction (IABR).

Methods: From 2007 to 2014, data of patients with stage II-III breast cancer of ≤ 70-years-old who received total mastectomy (TM) from two institutions were extracted. Exclusion criteria were: previous contralateral breast cancer, follow-up loss before adjuvant therapy completion, and artificial reconstruction. Patients were divided into two groups; 1) TM alone and 2) TM+IABR. Overall survival (OS) and loco-regional recurrence free survival (LRRFS) were calculated and minor revision, abnormal volume on CT, and breast height change were observed.

Results: Sixty-one of 188 patients received IABR after TM. Neoadjuvant chemotherapy and postoperative radiotherapy was done in 27 and 80 patients, respectively. Fifty-nine percent, 19.2%, and 21.8% of patients were in stage II, IIIA, and IIIB-C, respectively. Stage IIIB-C was the most important prognostic factor for OS and LRRFS. In a median of 56.8 follow-up months, 5-year TM and TM+IABR OS rate were 96.8% and 100% for stage II (P=0.324) and 57.6%, 95.5% and 91.7% for stage IIIA (P=0.698), and 62.5% for stage IIIB-C (P=0.544), respectively. Five-year TM and TM+IABR LRRFS were 98.1% and 95.7% for stage II (P=0.998)91.1% and 100% for stage IIIA (P=0.277), and 70.8% and 62.5% for stage IIIB-C (P=0.378), respectively. However, two locoregional failures after 5-years were developed in stage IIIB-C of TM+IABR at 71 and 94 months. Minor revisions 3 months of IABR, including two major complications, were done in 49.2%. The reduction of breast height was 21.2% (11/52) and 31.9% (15/47) in about 18 months and about 42 months observations after IABR, respectively. The volume of abnormal imaging was over 10 cc in 27.3% (15/55) on CT of 6 months after IABR. Although minor revisions, abnormal volume on CT, and breast height change were common, they were not related to therapeutic methods, including radiotherapy and tumor stage.

Conclusions: In about 5-years follow-up, IABR did not aggravate oncologic outcomes, and adjuvant radiotherapy was not closely related with quality of reconstruction. It must be considered, however, that absolute oncologic outcomes of advanced stage were not sufficient, and minor problems post-IABR were commonly developed.

Citation Format: Yoon WS, Yang DS, Son GS, Woo SU, Kim D-W, Dhong E-S, Chang YW. Oncologic outcomes and reconstruction quality of immediate autologous breast reconstruction in intermediate and locally advanced breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-16-18.

Abstract P3-12-17: Can radiation dosimetric parameters explain severe skin reaction during adjuvant whole breast irradiation applying field-in-field technique?

Aim: Although modern radiotherapy such as field-in-field technique decreased the radiation toxicity, skin reaction is still frequent and main problem during adjuvant whole breast irradiation. Our study investigated various radiation dosimetric and clinical parameters as the risk factors of severe skin reaction.

Methods: From January 2012 to December 2014, total 219 patients with breast conserving surgery and adjuvant whole breast irradiation were retrospectively reviewed. All patients took both whole breast irradiation (50 Gy/25 fractions) and boost to the tumor bed (10 - 15 Gy). Skin reaction was measured by comparing the photography of radiation field between the first day of whole breast irradiation and boost therapy. For each axilla and inferior fold, the intensity (score 1 to 5) and extent (score 0 to 1) of erythema were recorded and summed. The severe skin reaction was defined as score 5 or 6. The relations of various radiation dosimetric parameters for radiotherapy planning, personal breast characteristics and clinical factors to severe skin reaction were evaluated using the Logistic regression tests.

Results: Total 75 (34%) and 57 (26%) patients showed the severe skin reaction to axilla and inferior fold, respectively. The variables of P &lt; 0.2 in univariate analyses including age, the body mass index, the breast height, the V100, the calculated point dose in radiation planning system, the breast separation, the field size, and the gradient of inferior fold entered the multivariate analyses. Age (P=0.013 (OR = 0.950, 95% CI 0.913 - 0.989)), the body mass index (P = 0.015 (OR = 1.123, 95% CI 1.023 - 1.233)), the calculated axilla point dose (P = 0.091 (OR = 1.064, 95% CI 0.990 - 1.142)), and the gradient of inferior fold (P = 0.073 (OR = 1.029, 95% CI 0.997 - 1.063)) were risk factors for severe axilla skin reaction, whereas age (P = 0.018 (OR = 0.948, 95% CI 0.907 - 0.991)) and the V100 (P &lt; 0.001 (OR = 1.005, 95% CI 1.003 - 1.007)) were for severe inferior fold skin reaction.

Conclusion: In addition to clinical factor and personal breast characteristics, the radiation dosimetric parameters such as calculated point dose and V100 could be another predictive factors of severe skin reaction.

Citation Format: Yoon WS, Lee NK, Lee JA, Yang DS, Kim CY, Son GS, Chang YW. Can radiation dosimetric parameters explain severe skin reaction during adjuvant whole breast irradiation applying field-in-field technique?. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-12-17.

Association of aldehyde dehydrogenase 1 expression and biologically aggressive features in breast cancer

Aldehyde dehydrogenase 1 (ALDH1) has been regarded as a breast cancer stem cell marker. Several studies have reported that ALDH1 expression is associated with poor prognosis in breast cancer. We aimed, therefore, to determine the prognostic value of ALDH1 expression and its association with several biomarkers in breast cancer tissue using immunohistochemistry. Furthermore, we investigated the characteristics of and differences between cellular and stromal expression of ALDH1. We performed tissue microarray (TMA) analysis of 425 breast cancer tissue samples collected during surgery. Immunohistochemical staining was then performed to measure the expression of ALDH1 and other breast cancer biomarkers. Statistical analysis of the relationship between ALDH1 expression and clinicopathologic characteristics was performed for 390 TMA samples. We found that ALDH1 was expressed in 71 cases (18.2%) in the tumor cells and/or stroma. Of these cases, 38 (9.7%) showed ALDH1 expression in tumor cells and 38 (9.7%) showed ALDH1 expression in the stroma. ALDH1 expression was significantly associated with markers of a poor prognosis, such as young age, estrogen receptor negativity, progesterone receptor negativity, a high histological grade, and a high Ki-67 index. However, ALDH1 expression was not associated with p53, transforming growth factor-beta, Gli-1, YKL-40, or sonic hedgehog expression status. With regard to the expression site, the clinical characteristics did not differ between cases of cellular expression and those of stromal expression. However, ALDH1 expression in tumor cells was correlated with hormone receptor status, histological grade, molecular subtype, epidermal growth factor receptor expression status, and cytokeratin 5/6 expression status while stromal expression of ALDH1 was only correlated with hormone receptor status. Overall, these findings suggest that ALDH1 expression in tumor tissue is associated with a biologically aggressive phenotype.

KEYWORDS

ALDH1, biologically aggressive, breast cancer.

The effectiveness of gadolinium MRI to improve target delineation for radiotherapy in hepatocellular carcinoma: a comparative study of rigid image registration techniques

To achieve consistent target delineation in radiotherapy for hepatocellular carcinoma (HCC), image registration between simulation CT and diagnostic MRI was explored. Twenty patients with advanced HCC were included. The median interval between MRI and CT was 11 days. CT was obtained with shallow free breathing and MRI at exhale phase. On each CT and MRI, the liver and the gross target volume (GTV) were drawn. A rigid image registration was taken according to point information of vascular bifurcation (Method[A]) and pixel information of volume of interest only including the periphery of the liver (Method[B]) and manually drawn liver (Method[C]). In nine cases with an indefinite GTV on CT, a virtual sphere was generated at the epicenter of the GTV. The GTV from CT (VGTV[CT]) and MRI (VGTV[MR]) and the expanded GTV from MRI (V+GTV[MR]) considering geometrical registration error were defined. The underestimation (uncovered V[CT] by V[MR]) and the overestimation (excessive V[MR] by V[CT]) were calculated. Through a paired T-test, the difference between image registration techniques was analyzed. For method[A], the underestimation rates of VGTV[MR] and V+GTV[MR] were 16.4 ± 8.9% and 3.2 ± 3.7%, and the overestimation rates were 16.6 ± 8.7% and 28.4 ± 10.3%, respectively. For VGTV[MR] and V+GTV[MR], the underestimation rates and overestimation rates of method[A] were better than method[C]. The underestimation rates and overestimation rates of the VGTV[MR] were better in method[B] than method[C]. By image registration and additional margin, about 97% of HCC could be covered. Method[A] or method[B] could be recommended according to physician preference.

Changes in plasma concentrations of risperidone and 9-hydroxyrisperidone and the associated clinical effects during the switch from oral risperidone to extended-release paliperidone tablets in patients with schizophrenia

This study aimed to investigate changes in plasma concentrations of risperidone and 9-hydroxy-risperidone (9-OHR) and the associated clinical effects when switching from oral risperidone to extended-release (ER) paliperidone in patients with schizophrenia. This study included 25 patients with schizophrenia. Following a one-week screening period with a stable dose of risperidone, a six-week open-label switch study from risperidone to extended-release paliperidone (paliperidone ER) was conducted. Efficacy and safety assessments were performed on Day 1 and at Weeks 1, 2, 4, and 6. Plasma levels of the active fractions of oral risperidone and paliperidone ER were measured on Day 1 and at Week 1, respectively. Plasma levels of the active moiety (risperidone plus 9-OHR) while taking risperidone (mean dose: 4.0 mg) were significantly higher than plasma levels of 9-OHR while taking 6 mg of paliperidone ER. For 12 subjects taking only 3 mg of risperidone, plasma concentrations of the active moiety of risperidone were also significantly higher than those of 9-OHR while taking 6 mg of paliperidone ER. The amount of reduction in plasma levels was correlated with a temporal deterioration of clinical symptoms. These findings suggest that for patients with schizophrenia taking 3 mg or more of risperidone, an initial switching dose of 6 mg of paliperidone ER may be relatively low in terms of subsequent plasma concentrations and the associated clinical response.

Abstract P2-02-08: MRI in predicting pathological response of breast cancer after neoadjuvant chemotherapy: Correlation with tumor size and morphology changes

PURPOSE

Contrast enhanced MR imaging is widely used to monitor the response of neoadjuvant chemotherapy (NAC) in breast cancer patients. The objectives of the study are 1) to assess the response of neoadjuvant chemotherapy (NAC) according to molecular biomarker status using MRI, 2) to evaluation of changes in morphological variation, and 3) to compare MR imaging-pathological size discrepancy depending on molecular biomarker status.

MATERIALS AND METHODS

Between May 2007 and March 2012, a total of 47 patients (age range, 34-65 years; mean age, 48 years) underwent NAC prior to surgery. Among them, 34 patients who performed MRI before and after NAC were enrolled. The extent of the lesion is measured by longest diameter. The response to NAC was calculated as reduction rate between pre NAC MRI and post NAC MRI. Histological grading system - Miller and Payne grade - was also recorded. Patients were divided into subgroups based on human epidermal growth factor receptor 2 (HER2), hormone receptors (HRs), and the proliferation marker Ki-67 status. The morphologic changes were classified into 1) concentric reduction, 2) fragmentation, 3) non-mass like, and 4) architectural distortion.

RESULTS

Total of 34 lesions from 34 patients were included. Among them, 12 lesions (35.3%) were pathologically proven to have no residual tumor (Miller and Payne grade 5). The mean MR reduction rate tended to be higher in HER2-positive (62.7%) and triple negative subgroups (61.9%) than HR-positive subgroup (47.7%). The mean MR imaging-pathologic size discrepancy tended to be smaller in triple negative subgroup (0.5cm) than HER2-positive (1.2cm) and HR-positive subgroups (1.4cm). All results showed no statistical significance (P&gt;0.05). Ki-67 expression showed no significant correlations in tumor response (r = 0.17, P = 0.4) and MR imaging-pathologic size discrepancy (r = 0.1, P = 0.6). The majority of morphologic change is concentric reduction (57.6%). MRI is tended to overestimate residual size of the lesion (62.5%)

CONCLUSION

HER2-positive and triple negative subgroups showed relatively better response. Tumors were most likely to response in the manner of concentric reduction. The mean MR imaging-pathologic size discrepancy tended to be smaller in triple negative subgroup. MRI is reliable method in predicting histopathological response to NAC, but is more likely to overestimate the residual size of the lesion.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-02-08.

Risk factors related to interfractional variation in whole pelvic irradiation for locally advanced pelvic malignancies

PURPOSE

The goal of the present study was to demonstrate risk factors affecting the interfractional variation in whole pelvic irradiation.

PATIENTS AND METHODS

Daily image acquisitions of 101 patients with locally advanced pelvic malignancy were undertaken using a kilo-voltage orthogonal on-board imager. The baseline deviation (the shift between the initial treatment and each fraction; Value(Base)) and day-to-day variation (the shift between the previous treatment and each fraction; Value(DD)) were measured. The standard deviations (SD) along the x- (right-left), y- (cranial-caudal), and z- (anterior-posterior) axes (SD[x], SD[y], and SD[z], respectively), the 3D vector of the SD (SD[3D]), and the mean of 3D shift (mean[3D]) were calculated in each patient. Various clinical factors, lumbar pelvic balance and rotation, and the shift of 5 consecutive fractions from the initial treatment (Value(5Fx)) were investigated as risk factors.

RESULTS

The prone set-up showed a larger mean(Base)[3D] than in the supine position (p =0 .063). A body mass index (BMI) ≥ 30 kg/m(2) resulted in the largest mean(DD)[3D] (p = 0.078) and SD(DD)[3D] (p = 0.058). All the SD(5Fx) along the x-, y-, and z-axes had moderate linear relationships with SD(Base) and SD(DD) (p < 0.001). The SD(5Fx)[3D] also had a moderate linear relationship with the mean(Base)[3D], mean(DD)[3D], SD(Base)[3D], and SD(DD)[3D] (p < 0.001). In multivariate analysis, the SD(5Fx) had the same significant relationship with SD(Base) and SD(DD) (p < 0.001). A BMI ≥ 30 kg/m(2) was associated with the largest SD(DD)[x] (p = 0.003).

CONCLUSION

Close surveillance through high-quality and frequent image guidance is recommended for patients with extensive variations of the initial five consecutive fractions or obesity.

TGFα and EGFR in ovine preimplantation embryos and effects on development

The present study aimed to assess location and relative amounts of transforming growth factor alpha (TGFalpha) and its receptor (EGFR) in ovine oocytes and preimplantation embryos by using immunohistochemical technique that was graded on a relative scale of 0-3, with 0 representing absence of staining, and 3 exhibiting prominent staining, and to evaluate the effects of TGFalpha/EGF on in vitro development of preimplantation embryos by adding different concentrations of EGF and TGFalpha to culture medium. The results showed that EGFR was abundant in cell plasma membranes in immature and mature oocytes, cumulus cells of immature cumulus-oocyte complexes (COC), fertilized oocytes and at different stages of embryo development. However, the relative amounts in inner cell mass (ICM) (1+) was less than that in trophectoderm (TE) cells (2+) at the blastocysts stage. The staining pattern for TGFalpha was a similar to EGFR. However, the staining for TGFalpha slightly increased in the fertilized oocytes (1-2+) as compared to immature and mature oocytes (1+). TGFalpha was mainly detected in the cytoplasm close to the membrane in both ICM and trophectoderm (TE) cells. The developmental rate of 8-cell stage embryos cultured with 5 ng/ml TGFalpha was increased as compared to other treatments (P<0.05). There was no significant difference in the rate of development of blastocysts cultured with 5 ng/ml TGFalpha, 20 ng/ml EGF, 20 ng/ml EGF+5 ng/ml TGFalpha or the control treatment (P>0.05). In addition, there was no significant difference in the number of cells in blastocyst stage as compared with different treatments (P>0.05). However, TGFalpha alone enhanced cell survival rated (P<0.01) and reduced apoptosis. We concluded that TGFalpha can improve development of ovine preimplantation embryos at the 8-cell and blastocyst stages in vitro.

Locally applied simvastatin promotes fracture healing in ovariectomized rat

Simvastatin solution was injected subcutaneously to the site of fractured tibiae of ovariectomized rats. Afterwards healing quality was evaluated by morphologic, radiographic, biomechanical, histological and histomorphometric methods at 1, 2 and 4 weeks after fracture. Results showed that locally applied simvastatin improved fracture healing.

INTRODUCTION

Many studies have documented an anabolic effect of hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, statins, on undisturbed bone. Reports of their effects, however, on fractured skeletal systems have been limited. A study was, therefore, conducted to check the effects of statins on fracture healing.

METHODS

Simvastatin (10 mg/kg/day) was injected subcutaneously to tissue overlying the site of fractured tibiae of ovariectomized rats for a treatment period of 5 days. Vehicle reagent was used as a control. Healing quality was evaluated at 1, 2 and 4 weeks after fracture.

RESULTS

Compared with that in the vehicle group, the callus cross-section area in simvastatin-treated rats was significantly enlarged by 21.3% (p < 0.05) at 1 week and by 21.5% (p < 0.05) at 2 weeks; new woven bone was relatively substantive and arranged more tightly and regularly at 2 and 4 weeks; and maximal load was increased by 57.5% (p < 0.05) at 2 weeks and by 31.4% (p < 0.05) at 4 weeks. Histomorphometrically, simvastatin was associated with a significant (p < 0.05) increase of mineralization width (MLW), mineralization volume (MLV) and mineral apposition rate (MAR).

CONCLUSION

The current study suggests that local application of simvastatin could promote fracture healing in ovariectomized rats.

Differences of cortical activation pattern between cortical and corona radiata infarct

The aim of this study was to elucidate the differences of cortical activation pattern between patients with cortex (CO) infarct and those with corona radiata (CR) infarct. Twenty chronic patients with cerebral infarct and 11 normal subjects were recruited. The patients were classified into two groups according to infarct location: CO and CR group. After functional MRI was performed during the motor task of hand grasp-release movements, the hand motor function was assessed. The CO group tended to be activated on the contralateral primary sensori-motor cortex, whereas the CR group largely showed activation of the bilateral primary sensori-motor cortex. Namely, there was significantly more lateralized activation pattern of primary sensori-motor cortex in the CO group than in the CR group. Additionally, the CO group had better hand motor function than the CR group. Our results suggest that the motor recovery mechanism vary according to the lesion location between CO and CR infarct, indicating that the adaptive cortical reorganization proceeds under different patterns according to the lesion location.

Degeneration speed of corticospinal tract in patients with cerebral infarct

OBJECTIVES

Diffusion tensor image tractography (DTT) could be useful for exploring the state of the corticospinal tract (CST) at the level of the subcortical white matter. The purpose of this study was to demonstrate the speed of degeneration of the CST in patients with cerebral infarct, using DTT.

DESIGN

Two patients with middle cerebral artery territory infarct were recruited for this study. DTT was performed 5 times with an interval of 7 days, starting at 2 days after onset, using a 1.5-T system with a synergy-L Sensitivity Encoding head coil. The termination criteria used were fractional anisotrophy < 0.3, 0.2, 0.1, respectively, and an angle change > 45 degrees .

RESULTS

Detection of CST degeneration began at the 9 day DTT in both patients. The most rapid CST degeneration was noted for 7 days at 16 days from onset. We did not detect any tract in the affected hemisphere of both patients at the 23-day DTT.

CONCLUSIONS

We demonstrated that CST degeneration begins before 9 days from onset and progresses rapidly in patients with middle cerebral artery territory infarct. It seems that the CST degeneration began earlier than expected.

Motor recovery via the peri-infarct area in patients with corona radiata infarct

OBJECTIVES

Diffusion tensor image tracography (DTT) could be useful for exploration of the state of the corticospinal tract at the subcortical white matter level. We investigated the neural pathway associated with motor recovery in the patients with corona radiata infarct (CR) using DTT.

DESIGN

Three hemiparetic patients who showed severe weakness of the affected upper extremity at stroke onset, were recruited. DTT was performed twice (subacute and chronic stage) using 1.5-T system. Three-dimensional reconstructions of the fiber tracts were obtained with FA <0.2, angle >45 degrees as termination criteria.

RESULTS

In all patients, the motor function of the affected upper extremity has recovered to be functional state at second DTT scanning. The motor tracts of the affected hemisphere were observed to pass along the posterior portion of the CR infarct on both the first and second DTT.

CONCLUSIONS

It seems that the motor function of the affected upper extremity of the patients recovered via the posterior portion of infarct. This finding may reflect functional reorganization of the motor pathway following damage to the corticospinal tract.

Cortical activation changes induced by visual biofeedback tracking training in chronic stroke patients

OBJECTIVES

We tried to examine whether visual biofeedback tracking training (VBTT) can improve both the gait performance and cortical activation pattern in chronic stroke patients.

DESIGN

We enrolled 10 chronic hemiparetic patients with stroke(mean age 46.3 +/- 5.19 years). The patients were randomly assigned to the training group (5 patients) or the control group (5 patients). VBTT was to follow the PC-generated sine waves with the knee joint electrogoniometer, and the two sine waves should appear as close to overlapping as possible on the PC monitor. The training was performed for 39 minutes/day, 5 days/week, for 4 weeks. Pre-training and post-training accuracy of tracking, functional status of gait, and functional MRI (fMRI) were measured. fMRI was performed at 1.5 T in parallel with timed knee flexion-extension movements at a fixed rate.

RESULTS

The accuracy of the tracking performance, walking speed, and motor scale for gait improved in the training group. Primary sensorimotor cortex (SM1) cortical activation shifted significantly from the unaffected to the affected hemisphere in the training group.

CONCLUSIONS

We demonstrated that cortical activation changes occurred with gait function improvement in chronic stroke patients throughout the 4-week VBTT program. It seems that the cortical reorganization was induced by VBTT.

Peri-infarct reorganization of motor function in patients with pontine infarct

OBJECTIVES

Combined functional MRI (fMRI) and diffusion tensor tractography (DTT) imaging provides a powerful vehicle for the investigation of motor recovery mechanisms. Using this combined method, we investigated the motor recovery mechanism in patients with pontine infarct.

DESIGN

We evaluated six healthy control subjects and two patients with pontine infarct at 6 months from onset. fMRI was performed at 1.5 T with timed hand grasp-release movements. For DTT, we used each of the 32 noncollinear diffusion-sensitizing gradients. Three-dimensional reconstructions of the fiber tracts were obtained with FA <0.3, angle >45 degrees as termination criteria.

RESULTS

fMRI data revealed activation only in the contralateral primary sensorimotor cortex during movement of either hand. DTI findings from controls and the unaffected hemisphere of the patients showed that the corticospinal tract descended through the known corticospinal tract pathway. However, the tracts of the affected hemisphere in the patients were observed to pass along peri-infarct areas (patient 1: lateral, patient 2: posterior) in the pons.

CONCLUSIONS

It seems that the peri-infarct areas compensate for corticospinal tract damage at the pons; this may be one mechanism of motor recovery for patients with pontine infarct.

Cortical Reorganization of Hand Motor Function to Primary Sensory Cortex in Hemiparetic Patients With a Primary Motor Cortex Infarct

OBJECTIVE

To show cortical reorganization in hemiparetic patients with a primary motor cortex (M1) infarct including the precentral knob by using functional magnetic resonance imaging (fMRI).

DESIGN

Case-control.

SETTING

Outpatient clinics in the rehabilitation department of a university hospital.

PARTICIPANTS

Two stroke patients and 20 control subjects.

INTERVENTIONS

By using fMRI, we evaluated the hand motor function of 2 hemiparetic stroke patients, who had made some recovery from complete paralysis of the affected hand, and 20 control subjects.

MAIN OUTCOME MEASURES

fMRI was performed by using the blood oxygen level-dependent technique at 1.5 T with a standard head coil. The motor task paradigm consisted of hand grasp-release movements.

RESULTS

The contralateral primary sensorimotor cortex was activated by the hand movements of the control subjects and of the unaffected side of the 2 patients. Only the contralateral (infarct side) primary sensory cortex (S1) was activated by the movements of the affected hand of the 2 patients, a result that was not observed in the control subjects or with the unaffected hand in the stroke patients.

CONCLUSIONS

The hand motor function associated with the infarcted M1 in our patients was reorganized into the S1. These results suggest cortical reorganization in patients with an M1 infarct.

Structure determination of a lone alpha-helical antifreeze protein from winter flounder

The X-ray crystal structure of a lone alpha-helical antifreeze protein from winter flounder has been determined to 1.5 A using a combination of molecular-replacement and isomorphous-replacement techniques. Molecular replacement involved a multiparameter search using X-PLOR with two 37-mers of alanine in idealized alpha-helical conformations as the search models. Identified were a large number of potential solutions from which the correct solution was not distinguishable. Commitment of the top 1620 solutions to cycles of rigid-body, positional and simulated-annealing refinement identified the correct solution by a small margin in R factor. Low-resolution electron-density maps generated with phasing information from TbNO(3) and LaNO(3) derivatives were consistent with the top molecular-replacement solution. These derivatives also provided a means to filter and compare the large number of other molecular-replacement solutions with reasonable R factor statistics. The structure-solution strategy described herein may prove useful for the determination of other relatively simple alpha-helical X-ray structures.

Motor recovery mechanism of diffuse axonal injury: a combined study of transcranial magnetic stimulation and functional MRI

PURPOSE

The purpose of this study was to investigate the motor recovery mechanism following diffuse axonal injury (DAI) using transcranial magnetic stimulation (TMS) and functional MRI (fMRI).

METHODS

Twenty-six hands of 13 control subjects and 14 affected hands of 8 patients (two hemiparetics and six quadriparetics) were evaluated. All the patients were initially diagnosed with DAI and were evaluated after they had reached their maximal motor recovery. fMRI was performed at 1.5 T using a hand grasp-release movement paradigm and TMS was applied with a round coil over the vertex.

RESULTS

fMRI revealed that both normal subjects and patients with DAI showed increased contralateral primary sensori-motor cortex activation during affected hand movement. The motor evoked potentials (MEPs) of the patient group was slightly delayed in latency and significantly increased in duration and turns. The relative MEP amplitude, phase, and excitatory threshold were not significantly different between the groups.

CONCLUSIONS

These findings may indicate the heterogeneity of the axons in the recovery process of the corticospinal tract. It seems that the motor recovery in patients who had suffered DAI was attributable to the recovery of the corticospinal tract.

Short-latency ocular following in humans: sensitivity to binocular disparity

We show that the initial ocular following responses elicited by motion of a large pattern are modestly attenuated when that pattern is shifted out of the plane of fixation by altering its binocular disparity. If the motion is applied to only restricted regions of the pattern, however, then altering the disparity of those regions severely attenuates their ability to generate ocular following. This sensitivity of the ocular tracking mechanism to local binocular disparity would help the observer who moves through a cluttered 3-D world to stabilize objects in the plane of fixation and ignore all others.

Presenilin function: connections to Alzheimer's disease and signal transduction

Missense mutations in presenilin 1 (PS1) and presenilin 2 (PS2) are associated with early-onset familial Alzheimer's disease which displays an accelerated deposition of amyloid plaques and neurofibrillary tangles. Presenilins are multi-spanning transmembrane proteins which localize primarily to the endoplasmic reticulum and the Golgi compartments. We have previously demonstrated that PS1 exists as a high-molecular-mass complex that is likely to contain several functional ligands. Potential binding proteins were screened by the yeast two-hybrid system using the cytoplasmically orientated PS1 loop domain which was shown to interact strongly with members of the armadillo family of proteins, including beta-catenin, p0071 and a novel neuron-specific plakophilin-related armadillo protein (NPRAP). Armadillo proteins can have dual functions that encompass the stabilization of cellular junctions/synapses and the mediation of signal transduction pathways. Our observations suggest that PS1 may contribute to both aspects of armadillo-related pathways involving neurite outgrowth and nuclear translocation of beta-catenin upon activation of the wingless (Wnt) pathway. Alzheimer's disease (AD)-related presenilin mutations exhibit a dominant gain of aberrant function resulting in the prevention of beta-catenin translocation following Wnt signalling. These findings indicate a functional role for PS1 in signalling and suggest that mistrafficking of selected presenilin ligands may be a potential mechanism in the genesis of AD.

All or none fibrillogenesis of a prion peptide

Amyloid proteins and peptides comprise a diverse group of molecules that vary both in size and amino-acid sequence, yet assemble into amyloid fibrils that have a common core structure. Kinetic studies of amyloid fibrillogenesis have revealed that certain amyloid proteins form oligomeric intermediates prior to fibril formation. We have investigated fibril formation with a peptide corresponding to residues 195-213 of the human prion protein. Through a combination of kinetic and equilibrium studies, we have found that the fibrillogenesis of this peptide proceeds as an all-or-none reaction where oligomeric intermediates are not stably populated. This variation in whether oligomeric intermediates are stably populated during fibril formation indicates that amyloid proteins assemble into a common fibrillar structure; however, they do so through different pathways.

Mechanism of uterine vascular refractoriness to endothelin-1 in pregnant sheep

Endothelin-1 (ET-1) is a potent vasoconstrictor and produces marked pressor responses when given systemically. Studies in sheep have demonstrated that during pregnancy the uterine vasculature is refractory to exogenously administered ET-1. We hypothesize that this pregnancy-dependent refractoriness is due to an upregulation of local uterine metabolism of ET-1 and/or ET(B) receptors and/or downregulation of local uterine ET(A) receptors. To investigate these possibilities, 21 nonpregnant and 17 pregnant sheep were used. Dose-response curves to intravenous infusion of ET-1 and phenylephrine were generated for pregnant and nonpregnant sheep. ET-1 infused systemically demonstrated vasoconstriction in the systemic and renal vasculature of pregnant and nonpregnant animals and vasoconstriction in the uterine vasculature of nonpregnant animals. The pregnant animals showed no uterine vascular response to ET-1. In contrast, phenylephrine showed vasoconstriction in the systemic, renal, and uterine circulations in both pregnant and nonpregnant sheep. After experimentation, the animals were euthanized, and tissues were harvested for Western blot and activity analysis of neutral endopeptidase (NEP) or RT-PCR analysis of endothelin-converting enzyme (ECE) and ET(A) and ET(B) receptors. The content and activity of NEP in the uterine and renal vasculature of pregnant and nonpregnant animals were similar. RT-PCR demonstrated the presence of ECE in the uterine vasculature of pregnant and nonpregnant sheep. ET(A) receptor mRNA was significantly reduced in pregnant compared with nonpregnant sheep, whereas ET(B) receptor mRNA remained unchanged. We conclude that the uterine vascular refractoriness seen in the pregnant sheep is due to a downregulation of ET(A) receptors.

Assembly of Alzheimer's amyloid-beta fibrils and approaches for therapeutic intervention

Amyloid plaques are the principal features of Alzheimers disease (AD) pathology and are considered to be a major factor in the disease process. These fibrillar deposits are composed primarily of the 40-42 residue amyloid-beta (Abeta) peptide which is a proteolytic product of a larger membrane precursor protein. Electron microscopy and X-ray diffraction have revealed that the mature amyloid fibrils are assembled as a highly beta-sheet polymer that has a well-defined protofilament quaternary structure. This organization is observed for amyloid fibrils from a wide variety of disorders and appears to represent a structural superfamily. Amyloid plaques also contain a number of other components such as proteoglycans that contain highly sulfated glycosaminoglycan (GAG) chains. These amyloid-associated elements may contribute to the aggregation and/or stabilization of Abeta as insoluble fibrils. We have recently developed an aggressive model for Abeta plaque formation in transgenic mice that exhibits an "early-onset" phenotype. Immunocytochemistry has demonstrated that even with this rapid progression, Abeta deposits within the neuropil and cerebrovascular system all co-localize with heparan sulfate proteoglycans (HSPG). These findings indicate a number of structural features that can be targeted as potential sites for the development of amyloid inhibitors. In addition, the use of small compounds that interfere with the proteoglycan-amyloid pathway may be effective therapeutic agents that can be assessed through the use of these transgenic models.

Early-onset amyloid deposition and cognitive deficits in transgenic mice expressing a double mutant form of amyloid precursor protein 695

We have created early-onset transgenic (Tg) models by exploiting the synergistic effects of familial Alzheimer's disease mutations on amyloid beta-peptide (Abeta) biogenesis. TgCRND8 mice encode a double mutant form of amyloid precursor protein 695 (KM670/671NL+V717F) under the control of the PrP gene promoter. Thioflavine S-positive Abeta amyloid deposits are present at 3 months, with dense-cored plaques and neuritic pathology evident from 5 months of age. TgCRND8 mice exhibit 3,200-4,600 pmol of Abeta42 per g brain at age 6 months, with an excess of Abeta42 over Abeta40. High level production of the pathogenic Abeta42 form of Abeta peptide was associated with an early impairment in TgCRND8 mice in acquisition and learning reversal in the reference memory version of the Morris water maze, present by 3 months of age. Notably, learning impairment in young mice was offset by immunization against Abeta42 (Janus, C., Pearson, J., McLaurin, J., Mathews, P. M., Jiang, Y., Schmidt, S. D., Chishti, M. A., Horne, P., Heslin, D., French, J., Mount, H. T. J., Nixon, R. A., Mercken, M., Bergeron, C., Fraser, P. E., St. George-Hyslop, P., and Westaway, D. (2000) Nature 408, 979-982). Amyloid deposition in TgCRND8 mice was enhanced by the expression of presenilin 1 transgenes including familial Alzheimer's disease mutations; for mice also expressing a M146L+L286V presenilin 1 transgene, amyloid deposits were apparent by 1 month of age. The Tg mice described here suggest a potential to investigate aspects of Alzheimer's disease pathogenesis, prophylaxis, and therapy within short time frames.

Low-temperature increases the yield of biologically active herring antifreeze protein in Pichia pastoris

Antifreeze proteins and antifreeze glycoproteins are structurally diverse molecules that share a common property in binding to ice crystals and inhibiting ice crystal growth. Type II fish antifreeze protein of Atlantic herring (Clupea harengus harengus) is unique in its requirement of Ca(2+) for antifreeze activity. In this study, we utilized the secretion vector pGAPZalpha A to express recombinant herring antifreeze protein (WT) and a fusion protein with a C-terminal six-histidine tag (WT-6H) in yeast Pichia pastoris wild-type strain X-33 or protease-deficient strain SMD1168H. Both recombinant proteins were secreted into the culture medium and properly folded and functioned as the native herring antifreeze protein. Furthermore, our studies demonstrated that expression at a lower temperature increased the yield of the recombinant protein dramatically, which might be due to the enhanced protein folding pathway, as well as increased cell viability at lower temperature. These data suggested that P. pastoris is a useful system for the production of soluble and biologically active herring antifreeze protein required for structural and functional studies.

Observation of anharmonicity for copper thin film near room temperatures

The fluorescence EXAFS spectra for a copper thin film with a thickness of 3000A measured at 300K, 350K and 400K were analyzed by the regularization method to directly obtain the radial distribution. The pair distribution was almost symmetric for 300K but asymmetric for 350K and 400K. This indicates that the atoms in copper vibrate anharmonically near room temperatures. The anharmonicity and the skewness of the asymmetric distribu-tion increases as temperature increases.

Carboxyl-terminal fragments of Alzheimer beta-amyloid precursor protein accumulate in restricted and unpredicted intracellular compartments in presenilin 1-deficient cells

Absence of functional presenilin 1 (PS1) protein leads to loss of gamma-secretase cleavage of the amyloid precursor protein (betaAPP), resulting in a dramatic reduction in amyloid beta peptide (Abeta) production and accumulation of alpha- or beta-secretase-cleaved COOH-terminal fragments of betaAPP (alpha- or beta-CTFs). The major COOH-terminal fragment (CTF) in brain was identified as betaAPP-CTF-(11-98), which is consistent with the observation that cultured neurons generate primarily Abeta-(11-40). In PS1(-/-) murine neurons and fibroblasts expressing the loss-of-function PS1(D385A) mutant, CTFs accumulated in the endoplasmic reticulum, Golgi, and lysosomes, but not late endosomes. There were some subtle differences in the subcellular distribution of CTFs in PS1(-/-) neurons as compared with PS1(D385A) mutant fibroblasts. However, there was no obvious redistribution of full-length betaAPP or of markers of other organelles in either mutant. Blockade of endoplasmic reticulum-to-Golgi trafficking indicated that in PS1(-/-) neurons (as in normal cells) trafficking of betaAPP to the Golgi compartment is necessary before alpha- and beta-secretase cleavages occur. Thus, although we cannot exclude a specific role for PS1 in trafficking of CTFs, these data argue against a major role in general protein trafficking. These results are more compatible with a role for PS1 either as the actual gamma-secretase catalytic activity or in other functions indirectly related to gamma-secretase catalysis (e.g. an activator of gamma-secretase, a substrate adaptor for gamma-secretase, or delivery of gamma-secretase to betaAPP-containing compartments).

Alternate aggregation pathways of the Alzheimer beta-amyloid peptide. An in vitro model of preamyloid

Deposition of amyloid-beta (Abeta) aggregates in the brain is a defining characteristic of Alzheimer's disease (AD). Fibrillar amyloid, found in the cores of senile plaques, is surrounded by dystrophic neurites. In contrast, the amorphous Abeta (also called preamyloid) in diffuse plaques is not associated with neurodegeneration. Depending on the conditions, Abeta will also form fibrillar or amorphous aggregates in vitro. In this present study, we sought to characterize the properties of the amorphous aggregate and determine whether we could establish an in vitro model for amorphous Abeta. CD data indicated that Abeta40 assembled to form either a beta-structured aggregate or an unfolded aggregate with the structured aggregate forming at high peptide concentrations and the unstructured aggregate forming at low Abeta40 levels. The critical concentration separating these two pathways was 10 microm. Fluorescence emission and polarization showed the structured aggregate was tightly packed containing peptides that were not accessible to water. Peptides in the unstructured aggregate were loosely packed, mobile, and accessible to water. When examined by electron microscopy, the structured aggregate appeared as protofibrillar structures and formed classic amyloid fibrils over a period of several weeks. The unstructured aggregate was not visible by electron microscopy and did not generate fibrils. These findings suggest that the unstructured aggregate shares many properties with the amorphous Abeta of AD and that conditions can be established to form amorphous Abeta in vitro. This would allow for investigations to better understand the relationship between fibrillar and amorphous Abeta and could have significant impact upon efforts to find therapies for AD.

Examining the zinc binding site of the amyloid-beta peptide

The amyloid beta-peptide (Abeta) is a principal component of insoluble amyloid plaques which are characteristic neuropathological features of Alzheimer's disease. Abeta also exists as a normal soluble protein that undergoes a pathogenic transition to an aggregated, fibrous form. This transition can be affected by extraneous proteinaceous and nonproteinaceous elements, such as zinc ions, which may promote aggregation and/or stabilization of the fibrils. Protein chelation of zinc is typically mediated by histidines, cysteines and carboxylates. Previous studies have demonstrated that the Abeta-Zn2+ binding site is localized within residues 6-28 and that histidines may serve as the principal sites of interaction. To localize key residues within this region, a series of Abeta peptides (residues 1-28) were synthesized that contained systematic His/Ala substitutions. Circular dichroism and electron microscopy were used to monitor the effects of Zn2+ on the peptide beta-sheet conformation and fibril aggregation. Our results indicate that substitution of either His13 or His14 but not His6 eliminates the zinc-mediated effects. These observations indicate a specific zinc binding site within Abeta that involves these central histidine residues.

Chitinase genes responsive to cold encode antifreeze proteins in winter cereals

Antifreeze proteins similar to two different chitinases accumulate during cold acclimation in winter rye (Secale cereale). To determine whether these cold-responsive chitinases require post-translational modification to bind to ice, cDNAs coding for two different full-length chitinases were isolated from a cDNA library produced from cold-acclimated winter rye leaves. CHT9 is a 1,193-bp clone that encodes a 31.7-kD class I chitinase and CHT46 is a 998-bp clone that codes for a 24.8-kD class II chitinase. Chitinase-antifreeze proteins purified from the plant were similar in mass to the predicted mature products of CHT9 and CHT46, thus indicating that there was little chemical modification of the amino acid sequences in planta. To confirm these results, the mature sequences of CHT9 and CHT46 were expressed in Escherichia coli and the products of both cDNAs modified the growth of ice. Transcripts of both genes accumulated late in cold acclimation in winter rye. Southern analysis of winter rye genomic DNA indicated the presence of a small gene family homologous to CHT46. In hexaploid wheat, CHT46 homologs mapped to the homeologous group 1 chromosomes and were expressed in response to cold and drought. We conclude that two novel cold-responsive genes encoding chitinases with ice-binding activity may have arisen in winter rye and other cereals through gene duplication.

Chitinase genes responsive to cold encode antifreeze proteins in winter cereals

Antifreeze proteins similar to two different chitinases accumulate during cold acclimation in winter rye (Secale cereale). To determine whether these cold-responsive chitinases require post-translational modification to bind to ice, cDNAs coding for two different full-length chitinases were isolated from a cDNA library produced from cold-acclimated winter rye leaves. CHT9 is a 1,193-bp clone that encodes a 31.7-kD class I chitinase and CHT46 is a 998-bp clone that codes for a 24.8-kD class II chitinase. Chitinase-antifreeze proteins purified from the plant were similar in mass to the predicted mature products of CHT9 and CHT46, thus indicating that there was little chemical modification of the amino acid sequences in planta. To confirm these results, the mature sequences of CHT9 and CHT46 were expressed in Escherichia coli and the products of both cDNAs modified the growth of ice. Transcripts of both genes accumulated late in cold acclimation in winter rye. Southern analysis of winter rye genomic DNA indicated the presence of a small gene family homologous to CHT46. In hexaploid wheat, CHT46 homologs mapped to the homeologous group 1 chromosomes and were expressed in response to cold and drought. We conclude that two novel cold-responsive genes encoding chitinases with ice-binding activity may have arisen in winter rye and other cereals through gene duplication.

Nicastrin modulates presenilin-mediated notch/glp-1 signal transduction and betaAPP processing

Nicastrin, a transmembrane glycoprotein, forms high molecular weight complexes with presenilin 1 and presenilin 2. Suppression of nicastrin expression in Caenorhabditis elegans embryos induces a subset of notch/glp-1 phenotypes similar to those induced by simultaneous null mutations in both presenilin homologues of C. elegans (sel-12 and hop-1). Nicastrin also binds carboxy-terminal derivatives of beta-amyloid precursor protein (betaAPP), and modulates the production of the amyloid beta-peptide (A beta) from these derivatives. Missense mutations in a conserved hydrophilic domain of nicastrin increase A beta42 and A beta40 peptide secretion. Deletions in this domain inhibit A beta production. Nicastrin and presenilins are therefore likely to be functional components of a multimeric complex necessary for the intramembranous proteolysis of proteins such as Notch/GLP-1 and betaAPP.

Presenilin structure, function and role in Alzheimer disease

Numerous missense mutations in the presenilins are associated with the autosomal dominant form of familial Alzheimer disease. Presenilin genes encode polytopic transmembrane proteins, which are processed by proteolytic cleavage and form high-molecular-weight complexes under physiological conditions. The presenilins have been suggested to be functionally involved in developmental morphogenesis, unfolded protein responses and processing of selected proteins including the beta-amyloid precursor protein. Although the underlying mechanism by which presenilin mutations lead to development of Alzheimer disease remains elusive, one consistent mutational effect is an overproduction of long-tailed amyloid beta-peptides. Furthermore, presenilins interact with beta-catenin to form presenilin complexes, and the physiological and mutational effects are also observed in the catenin signal transduction pathway.

Copper(II)-induced conformational changes and protease resistance in recombinant and cellular PrP. Effect of protein age and deamidation

While PrP(C) rearranges in the area of codons 104-113 to form PrP(Sc) during prion infections, the events that initiate sporadic Creutzfeldt-Jakob disease are undefined. As Cu(II) is a putative ligand for PrP(C) and has been implicated in the pathogenesis of Creutzfeldt-Jakob disease and other neurodegenerative diseases, we investigated the structural effects of binding. Incubation of brain microsomes with Cu(II) generated approximately 30-kDa proteinase K-resistant PrP. Cu(II) had little effect on fresh recombinant PrP23-231, but aged protein characterized by conversion of Asn-107 to Asp decreased alpha-helical content by approximately 30%, increased beta-sheet content 100%, formed aggregates, and acquired proteinase K resistance in the presence of Cu(II). These transitions took place without need for acid pH, organic solvents, denaturants, or reducing agents. Since conversion of Asn to Asp proceeds by a spontaneous pathway involving deamidation, our data suggest that covalent variants of PrP(C) arising in this manner may, in concert with Cu(II), generate PrP(Sc)-like species capable of initiating sporadic prion disease.

Structural studies of soluble oligomers of the Alzheimer beta-amyloid peptide

Recent studies have suggested that non-fibrillar soluble forms of Abeta peptides possess neurotoxic properties and may therefore play a role in the molecular pathogenesis of Alzheimer's disease. We have identified solution conditions under which two types of soluble oligomers of Abeta40 could be trapped and stabilized for an extended period of time. The first type of oligomers comprises a mixture of dimers/tetramers which are stable at neutral pH and low micromolar concentration, for a period of at least four weeks. The second type of oligomer comprises a narrow distribution of particles that are spherical when examined by electron microscopy and atomic force microscopy. The number average molecular mass of this distribution of particles is 0.94 MDa, and they are are stable at pH 3 for at least four weeks. Circular dichroism studies indicate that the dimers/tetramers possess irregular secondary structure that is not alpha-helix or beta-structure, while the 0.94 MDa particles contain beta-structure. Fluorescence resonance energy transfer experiments indicate that Abeta40 moieties in amyloid fibrils or protofibrils are more similar in structure to those in the 0.94 MDa particles than those in the dimers/tetramers. These findings indicate that soluble oligomeric forms of Abeta peptides can be trapped for extended periods of time, enabling their study by high resolution techniques that would not otherwise be possible.

Extracellular expression, purification, and characterization of a winter flounder antifreeze polypeptide from Escherichia coli

HPLC6 is the major component of liver-type antifreeze polypeptides (AFPs) from the winter flounder, Pleuronectes americanus. To facilitate mutagenesis studies of this protein, a gene encoding the 37-amino acid mature polypeptide was chemically synthesized and cloned into the Tac cassette immediately after the bacterial ompA leader sequence for direct excretion of the AFP into the culture medium. Escherichia coli transformant with the construct placIQpar8AF was cultured in M9 medium. The recombinant AFP (rAFP) was detected by a competitive enzyme-linked immunosorbent assay (ELISA). After IPTG induction, a biologically active rAFP was expressed. The majority of the rAFP was excreted into the culture medium with only trace amounts trapped in the periplasmic space and cytoplasm. After 18 h of induction, the accumulated rAFP in the culture medium amounted to about 16 mg/L. The excreted AFP was purified from the culture medium by a single-step reverse-phase HPLC. Mass spectrometric and amino acid composition analyses confirmed the identity of the purified product. The rAFP, which lacked amidation at the C-terminal, was about 70% active when compared to the amidated wild-type protein, thus confirming the importance of C-terminal cap structure in protein stability and function.

Manipulating the amyloid-beta aggregation pathway with chemical chaperones

Amyloid-beta (Abeta) assembly into fibrillar structures is a defining characteristic of Alzheimer's disease that is initiated by a conformational transition from random coil to beta-sheet and a nucleation-dependent aggregation process. We have investigated the role of organic osmolytes as chemical chaperones in the amyloid pathway using glycerol to mimic the effects of naturally occurring molecules. Osmolytes such as the naturally occurring trimethylamine N-oxide and glycerol correct folding defects by preferentially hydrating partially denatured proteins and entropically stabilize native conformations and polymeric states. Trimethylamine N-oxide and glycerol were found to rapidly accelerate the Abeta random coil-to-beta-sheet conformational change necessary for fiber formation. This was accompanied by an immediate conversion of amorphous unstructured aggregates into uniform globular and possibly nucleating structures. Osmolyte-facilitated changes in Abeta hydration also affected the final stages of amyloid formation and mediated transition from the protofibrils to mature fibers that are observed in vivo. These findings suggest that hydration forces can be used to control fibril assembly and may have implications for the accumulation of Abeta within intracellular compartments such as the endoplasmic reticulum and in vitro modeling of the amyloid pathway.

Improved process for production of recombinant yeast-derived monomeric human G-CSF

The human granulocyte colony-stimulating factor (hG-CSF) was efficiently secreted at high levels in fed-batch cultures of recombinant Saccharomyces cerevisiae. However, the secreted recombinant hG-CSF (rhG-CSF) was shown to exist as large multimers in the culture broth due to strong hydrophobic interaction. It was hardly monomerized even by urea at high concentration. This multimer has been reported to diminish specific receptor-binding activity of hG-CSF and causes undesirable problems in the downstream process. When the rhG-CSF was secreted to extracellular broth in the presence of a non-ionic surfactant (Tween 80) in the culture media, the multimerization of the secreted rhG-CSF was efficiently prevented in the fed-batch cultures. Also, the monomer fraction and secreted efficiency of rhG-CSF were significantly increased at the higher culture pH (6.5). Without using any denaturing agents, the secreted rhG-CSF monomer was easily purified with high recovery yield and purity via a simple purification process under acidic conditions, consisting of diafiltration, cation exchange, and gel filtration chromatography. A lyophilization process devoid of intermonomer aggregation was also designed using effective stabilizing agents.

Novel secretion system of recombinant Saccharomyces cerevisiae using an N-terminus residue of human IL-1 beta as secretion enhancer

An N-terminus sequence of human interleukin 1beta (hIL-1beta) was used as a fusion expression partner for the production of two recombinant therapeutic proteins, human granulocyte-colony stimulating factor (hG-CSF) and human growth hormone (hGH), using Saccharomyces cerevisiae as a host. The expression cassette comprised the leader sequence of killer toxin of Kluyveromyces lactis, the N-terminus 24 amino acids (Ser5-Ala28) of mature hIL-1beta, the KEX2 dibasic endopeptidase cleavage site, and the target protein (hG-CSF or hGH). The gene expression was controlled by the inducible UAS(gal)/MF-alpha1 promoter. With the expression vector above, both recombinant proteins were well secreted into culture medium with high secretion efficiencies, and especially, the recombinant hGH was accumulated up to around 1.3 g/L in the culture broth. This is due presumably to the significant role of fused hIL-1beta as secretion enhancer in the yeast secretory pathway. In our recent report, various immunoblotting analyses have shown that the presence of a core N-glycosylation resident in the hIL-1beta fragment is likely to be of crucial importance in the high-level secretion of hG-CSF from the recombinant S. cerevisiae. When the N-glycosylation was completely blocked with the addition of tunicamycin to the culture, the secretion of hG-CSF and hGH was decreased to a negligible level although the other host-derived proteins were well secreted to the culture broth regardless of the presence of tunicamycin. The N-terminal sequencing of the purified hG-CSF verified that the hIL-1beta fusion peptide was correctly removed by in vivo KEX2 protease upon the exit of fusion protein from Golgi complex. From the results presented in this article, it is strongly suggested that the N-terminus fusion of the hIL-1beta peptide could be utilized as a potent secretion enhancer in the expression systems designed for the secretory production of other heterologous proteins from S. cerevisiae.

[Effect of selective lesions in hypothalamus on bilateral synchronized bursts of rat oxytocin neurons]

In order to clarify the location of the center for synchronized milk-ejection bursts of magnocellular oxytocin neurons in the hypothalamus, the bursts of these neurons were recorded extracellularly in lactating rats with selectively-cutting lesions of the middle brain or hypothalamus. Results showed that unilateral transection of the middle midbrain above the ventral tegmentum did not block the synchronized bursts on both sides; however, the synchronized bursts disappeared after unilateral transection through the middle of the medial hypothalamus. These results suggest that the area from the middle part of the midbrain to that of the hypothalamus does play a crucial role in the synchronized milk-ejection burst.

Secretory expression and site-directed mutagenesis studies of the winter flounder skin-type antifreeze polypeptides

Winter flounder contains both liver-type, extracellular antifreeze polypeptides (wflAFPs) and less active skin-type, intracellular antifreeze polypeptides (wfsAFPs). The lower activity of wfsAFPs might be due to their lack of complete ice-binding motifs '-K-DT-'. In order to test the functional role of this putative ice-binding motif, mutations were introduced into the N-terminal or C-terminal regions of wfsAFP-2, which lack any presumptive ice-binding motifs. The wild-type and mutant wfsAFP-2 were secreted in Escherichia coli culture media as mature antifreeze proteins and purified to homogeneity. Surprisingly, the antifreeze activity decreased with the introduction of ice-binding motifs. However, there was a corresponding decrease in alpha-helical content as well as thermal stability and this would suggest a compromise in retaining helical structure with the presence of ice-binding motifs. These studies have brought new definitions of the roles of ice-binding motif residues in type I antifreeze proteins.

Studies of a putative ice-binding motif in winter flounder skin-type anti-freeze polypeptide

Winter flounder contains two distinct anti-freeze protein isoforms, which are the liver-type extracellular anti-freeze proteins and the skin-type intracellular anti-freeze protein. The skin-type anti-freeze proteins exhibit lower anti-freeze activities than the liver-type isoforms and this might be due to their lacking complete ice-binding motifs. One of the skin-type anti-freeze proteins, skin-type anti-freeze protein-3, does contain putative overlapping ice-binding motifs with the sequences '-K-DT-' and '-DT-K-'. Synthetic anti-freezes containing 0-3 repeats of the '-DT-K-' motif were tested for stability and activity. Loss of the single '-DT-K-' of skin-type anti-freeze protein-3 increases the anti-freeze activity and increasing the number of motifs to two or three lowers the activity. The decrease in activity with an increasing frequency of the motif correlates with a decrease in the helical content of these peptides at 0 degrees C.

New clothes for amyloid enhancing factor (AEF): silk as AEF

Amyloid enhancing factor (AEF) is an activity that appears naturally during the course of persistent inflammation and precedes, by 24-48 h, AA amyloid deposition in appropriate murine models. AEF is defined by its biological properties, namely, when administered intravenously or intraperitoneally to a mouse, it primes the recipient for the rapid induction of AA amyloid when they are given an inflammatory stimulus. Available evidence indicates that AEF is protein in nature, but a specific molecular species (if a singular species exits) has not been identified. Past work (Ganowiak et al., Biochem. Biophys. Res. Commun. 199:306-312, 1994) has shown that AEF activity may be imparted to two different proteins (IAPP and beta-protein) provided each is organized in the form of an amyloid fibril. Since a characteristic property of proteins in amyloid fibrils is their beta-sheet organization, one possibility is that AEF activity, in part, depends on such organization, and other proteins with such properties may also have AEF activity. To investigate this possibility, silk, a protein which contains substantial beta-sheet content, was denatured in LiSCN and allowed to renature slowly under reducing conditions to form a gel. The denatured silk preparation was then sonicated thoroughly to permit intravenous injection and assessed for AEF activity. The modified silk, presented as small fibrils in a beta-sheet conformation as assessed by electron microscopy and circular dichroism, respectively. This silk at 0-50 micrograms/animal was administered intravenously as "AEF" followed immediately by subcutaneous AgNO3 as the inflammatory stimulus. Six days later the spleens were examined for the presence of AA amyloid and following Congo red staining, the amount of amyloid quantified by image analysis. Modified silk without an inflammatory stimulus, and non-sonicated modified silk, failed to induce AA amyloid. Sonicated modified silk followed by AgNO3 induced large quantities of splenic AA amyloid in a dose dependent fashion. Modified silk in quantities as small as 1-5 micrograms/animal can function as AEF. The AEF properties of the modified silk were stable at 4 degrees C for at least 4 weeks (the longest period tested). This procedure may provide a means of standardizing AEF preparations.