bluuebunny/crossref_metadata_2025 huggingface dataset:
Outdoor Falls Among Middle-Aged and Older Adults: A Neglected Public Health Problem
Authors: Li Wenjun , Keegan Theresa H.M. , Sternfeld Barbara , Sidney Stephen , Quesenberry Charles P. , Kelsey Jennifer L.
Published: May 2006

Objectives. Although risk factors for indoor falls among older individuals have been well studied, little is known about the etiology of outdoor falls. We examined risk factors for outdoor falls among middle-aged and older adults.

Methods. We analyzed data on the most recent fall during the past year among participants aged 45 years and older in the control group (N=2193) of a case–control study of fractures. The study was conducted at 5 Northern California Kaiser Permanente Medical Centers between 1996 and 2001.

Results. Falls occurred outdoors more often than indoors among most age groups. Study participants who reported more leisure-time physical activity had a higher risk for outdoor falls, and participants who were in poorer health had a greater risk for indoor falls. Most outdoor falls (73%) were precipitated by environmental factors, such as uneven surfaces and tripping or slipping on objects, and usually occurred on sidewalks, curbs, and streets. Walking (47.3%) was the most common fall-related activity.

Conclusions. Outdoor falls among adults aged 45 years and older were frequently attributable to modifiable environmental factors. With the widespread promotion of active lifestyles among older people, improvements in their outdoor environment are urgently needed.
The sedimentation of papermaking fibers
Authors: Young E. W. K. , Martinez D. M. , Olson J. A. , Buckley K. , Jivan S. , Ruth T. J. , Sossi V.
Published: May 2006

The motion of 18F radioactively labeled papermaking fibers settling in the midst of a suspension of nonradioactive fibers has been studied using positron emission tomography (PET). Various fractions were separated from the whole‐pulp suspension, radioactively labeled, and reintroduced into the original suspension. Tracer concentration profiles were measured dynamically throughout the sedimenting structure over the first 2 h of settling. These profiles were then used in conjunction with the Eulerian volume‐averaged two‐phase flow equations to estimate the permeability and solid‐phase stress functions for this suspension. Good agreement was found between the experimental data and the numerical model using particular functional forms for permeability and solid stress. The general approach outlined here can be used to examine the networking characteristics of different mixed suspensions of fibers. © 2006 American Institute of Chemical Engineers AIChE J, 2006
Serum adiponectin levels in cholesterol and pigment cholelithiasis
Authors: Wang S-N , Yeh Y-T , Yu M-L , Wang C-L , Lee K-T
Published: May 2006

Background

Altered adiponectin levels are associated with metabolic abnormalities. The aim of this study was to explore the role of adiponectin in cholelithiasis.

Methods

A radioimmunoassay was used to determine serum adiponectin levels in 58 patients with cholesterol gallstones and 47 with pigment gallstones, and 101 healthy controls. The chemical composition of extracted gallstones was determined by Fourier transform infrared spectroscopy.

Results

The mean(s.d.) adiponectin level was decreased in patients with cholesterol gallstones (7·6(4·1) µg/ml; P < 0·001) but raised in patients with pigment gallstones (17·9(9·0) µg/ml; P < 0·001) in comparison with healthy controls (11·7(6·5) µg/ml). Decreased adiponectin levels (odds ratio (OR) 0·85 (95 per cent confidence interval (c.i.) 0·76 to 0·96); P = 0·008) and female sex (OR 6·06 (95 per cent c.i. 2·10 to 17·46); P = 0·001) were associated with cholesterol gallstone formation. Increased adiponectin levels (OR 1·11 (95 per cent c.i. 1·01 to 1·22); P = 0·025) and increased age (OR 1·06 (95 per cent c.i. 1·01 to 1·12); P = 0·029) were associated with pigment gallstone formation. Raised serum aspartate aminotransferase concentration was a risk factor for both cholesterol (OR 1·16 (95 per cent c.i. 1·03 to 1·30); P = 0·013) and pigment (OR 1·23 (95 per cent c.i. 1·10 to 1·38); P < 0·001) gallstones.

Conclusion

Gallstone formation is associated with altered serum adiponectin levels. Serum adiponectin might serve as a novel marker for cholesterol and pigment cholelithiasis.
High expression levels of survivin protein independently predict a poor outcome for patients who undergo surgery for clear cell renal cell carcinoma
Authors: Parker Alexander S. , Kosari Farhad , Lohse Christine M. , Houston Thompson R. , Kwon Eugene D. , Murphy Linda , Riehle Darren L. , Blute Michael L. , Leibovich Bradley C. , Vasmatzis George , Cheville John C.
Published: May 2006

BACKGROUND

In a previous study of gene array data, the authors identified survivin as a candidate marker of aggressiveness in clear cell renal cell carcinoma (ccRCC). What remained in question was whether survivin expression at the protein level is an independent predictor of disease progression and cancer‐specific survival.

METHODS

Between 1990 and 1994, 312 patients underwent nephrectomy for ccRCC at Mayo Clinic Rochester and had paraffin tissue available. The authors performed immunohistochemistry with antisurvivin antibody, quantitated the expression by using an image‐analysis system, and analyzed the association of survivin expression with disease progression and cancer‐specific survival.

RESULTS

Within the cohort, 97 patients (31.1%) had high levels of survivin expression. Patients who had high survivin expression levels were at significantly increased risk of death from RCC compared with patients who had low expression levels (risk ratio [RR], 5.3; 95% confidence interval [95% CI], 3.5–7.9). The 5‐year cancer‐specific survival rate was 43.0% for patients with high survivin expression and 87.2% for patients with low survivin expression. In multivariate analysis, survivin expression remained associated with death from RCC even after adjusting for the Eastern Cooperative Oncology Group performance status; 2002 Tumor, Lymph Node, Metastases (TNM) stage groupings and nuclear grade (RR, 2.4; 95%CI, 1.5–3.8); and the Mayo Clinic composite TNM stage groupings, tumor size, nuclear grade, and tumor necrosis (SSIGN) score (RR, 1.8; 95%CI, 1.1–2.9). Among 273 patients who had localized ccRCC, survivin expression was associated significantly with cancer progression (RR, 3.9; 95%CI, 2.4–6.2).

CONCLUSIONS

Survivin expression is an independent predictor of ccRCC progression and death from RCC. Thus, survivin has the potential to offer additional prognostic information and to provide a novel target for the development of new adjuvant therapies. Cancer 2006. © 2006 American Cancer Society.
Pattern of carcinoembryonic antigen drop after laparoscopic radiofrequency ablation of liver metastasis from colorectal carcinoma
Authors: Ghanamah Mohammed , Berber Eren , Siperstein Allan
Published: May 2006

BACKGROUND

Laparoscopic radiofrequency ablation (RFA) is being increasingly used for local control of hepatic metastasis from colorectal carcinoma (CRC). After surgical resection of colorectal liver metastasis, carcinoembryonic antigen (CEA) values fall within 2 weeks, making this a useful parameter to follow shortly after surgery. Little is known, however, about the expected pattern of the CEA drop after RFA.

METHODS

From September 1998 to October 2002, RFA to CRC liver metastasis was performed on 144 patients. A subset of 17 patients were studied who had no evidence of extrahepatic disease preoperatively, had all detectable tumor ablated intraoperatively, and who on long‐term follow‐up (up to 15 months) had no evidence of recurrent disease. Serum CEA was determined preoperatively, on the first postoperative day, at 1 week, and every 3 months afterwards. A computed tomography (CT) scan of the abdomen and pelvis was obtained every 3 months postoperatively.

RESULTS

Ten (58.8%) patients showed an increase in CEA on postoperative Day 1, averaging 38.3% compared with the preoperative value. CEA then fell to 50% of the preoperative value, on average, on Day 7 postoperatively and only reached its nadir at 3 months.

CONCLUSIONS

Unlike resection patients, those undergoing ablation show an initial rise in CEA, probably due to release from the ablated tissue. Although heating of RFA would be expected to destroy CEA, the initial rise and slow drop postoperatively argue for a release of immunoreactive CEA from the ablated zone. This slow decline in CEA indicates that several months should pass before assessing the extent of potential residual disease. Cancer 2006. © 2006 American Cancer Society.
The contribution to adolescent well‐being made by nonfamily adults: An examination of developmental assets as contexts and processes
Authors: Scales Peter C. , Benson Peter L. , Mannes Marc
Published: May 2006

The contribution of nonfamily adults to young people's well‐being was explored using both a cross‐sectional national sample of 614 12‐ to 17‐yearolds and a longitudinal sample of 370 students followed from 6th–8th grades through 10th–12th grades. Both variable‐ and person‐centered analyses were employed. Young people's involvement in volunteering, youth programs, and religious organizations was hypothesized to increase the frequency as well as the quality of their relationships with nonfamily adults. Greater community involvement was related to (a) greater and qualitatively different kinds of engagement with nonfamily adults; (b) higher levels of positive developmental processes of support, empowerment, and boundary setting; (c) lower levels of risk behaviors; and (d) higher levels of thriving. The results suggest the utility of positive youth development theory, research, and applications for predicting and enhancing young people's concurrent and longer‐term well‐being. © 2006 Wiley Periodicals, Inc.
Characterisation of the leaf meals, protein concentrates and residues from some tropical leguminous plants
Authors: Agbede J Oluwasola
Published: May 2006

Leaf meals (LMs) from freshly harvested leaves of butterfly pea (Centrosema pubescens), devil bean (Mucuna pruriens), flamboyant flower (Delonix regia), Bauhinia tomentosa, coast wattle (Acacia auriculiformis), quick stick (Glyricidia sepium) and ipil‐ipil (Leucaena leucocephala) were analysed for their nutrient and anti‐nutritional content. Then, leaf protein concentrates (LPCs) were produced from the leaves by fractionation and characterised along with the fibrous residues. On average, the LM contained 181 g kg−1 dry matter (DM) CP (range: 100–280 g kg−1 DM), 139 g kg−1 DM crude fibre (range: 77–230 g kg−1 DM) and 133 g kg−1 DM ether extract (range: 86–165 g kg−1 DM) while the gross energy averaged 17.0 MJ kg−1. On average, leaf protein fractionation enhanced the CP, ether extract and the gross energy in the LPC by 39.5%, 33.5% and 22.0%, respectively, while the crude fibre of the LMs was reduced by 41%, on average, in the LPCs. Fractionation reduced the mineral content of the leaves generally. The mean phytin content varied from 0.36 g kg−1 in LPCs to 0.86 g kg−1 in leaf meal, while the mean phytin‐P content varied from 0.10 g kg−1 in LPCs to 0.24 g kg−1 in leaf meal. The total phenol levels in the LMs were reduced by 33.7% in the LPCs, on average. These results suggest that, while the LPCs from these plants could be used as protein supplements in non‐ruminant feeds in regions where there is an acute shortage of plant protein, the LMs or LPC fibrous residues could be fed to ruminant animals. Copyright © 2006 Society of Chemical Industry
Technical ethanol production from waste of cereals and its products using a complex enzyme preparation
Authors: Vidmantiene Daiva , Juodeikiene Grazina , Basinskiene Loreta
Published: May 2006

This paper describes a method for hydrolysing the polysaccharides from cereal‐derived waste to yield a sugar feedstock suitable for fermentation into technical ethanol using a complex of amylolytic and hemicellulolytic/cellulolytic enzymes. The enzymatic treatment of raw materials was carried out by liquid concentrated amylase and glucoamylase in combination with xylanase, containing also cellulase and glucanase activities. Gas chromatography was used for qualitative and quantitative analysis of end‐products. Apart from ethanol, also methanol, propanol, butanol, isoamyl and amyl alcohols, acetaldehyde, ethyl acetate and methyl acetate were found in the distillate. The optimal composition of amylase, glucoamylase and xylanase was selected, dependent on the raw material. The maximum ethanol concentration reached after fermentation of rye and wheat bran was 44 g L−1 and for rye and wheat grain it was 73 and 69 g L−1 respectively. By applying a complex preparation of amylolytic and hemicellulolytic/cellulolytic enzymes to cereal and cereal residues, it was possible to increase the ethanol yield by 20–45%, thereby decreasing the content of higher alcohols by 34% and significantly decreasing the methanol concentration, in comparison with a reference sample without xylanase preparation. Copyright © 2006 Society of Chemical Industry
Time‐domain and spectral‐domain optical coherence tomography in the analysis of brain tumor tissue
Authors: Böhringer H.J. , Boller D. , Leppert J. , Knopp U. , Lankenau E. , Reusche E. , Hüttmann G. , Giese A.
Published: May 2006

Introduction

Detection of residual tumor during resection of glial brain tumors remains a challenge because of a low inherent contrast of adjacent edematous brain, the surrounding infiltration zone, and the solid tumor. Therefore, new technologies that may facilitate an intraoperative analysis of the tissue at the resection edge are of great interest to neurosurgeons.

Materials and Methods

For ex vivo imaging of gliomas in a mouse model and human biopsy specimens of brain tumors and nervous system tissue we have used a time‐domain Sirius 713 Tomograph with a central wavelength of 1,310 nm and a coherence length of 15 µm equipped with a mono mode fiber and a modified optical coherence tomography (OCT) adapter containing a lens system for imaging at a working distance of 2.5 cm. A spectral‐domain tomograph using 840 nm and 930 nm superluminescence diodes (SLD) with a central wavelength of 900 nm was used as a second imaging modelity.

Results

Both time‐domain and spectral‐domain coherence tomography delineated normal brain, the infiltration zone and solid tumor in murine intracerebral gliomas. Histological evaluation of H&E sections parallel to the optical plain demonstrated that tumor areas of less than a millimeter could be detected and that not only solid tumor, but also brain invaded by a low‐density single tumor cells produced an OCT signal different from normal brain. Spectral‐domain OCT (SD‐OCT) demonstrated a significantly more detailed microstructure of tumor and normal brain up to a tissue depth of 1.5–2.0 mm, whereas the interpretation of time‐domain OCT (TD‐OCT) was difficult at a tissue depth >1.0 mm. Because of rapid scanning times SD‐OCT data could be acquired as 3D data maps, which allowed a multi‐planar analysis of the tumor to brain interface. Similar to our findings in experimental gliomas, images of human nervous system tissue acquired using SD‐OCT showed a characteristic signal of normal brain tissue and a detailed microstructure of tumor parenchyma.

Conclusion

Spectral‐domain OCT of experimental gliomas and human brain tumor specimens differentiates solid tumor, diffusely invaded brain tissue, and adjacent normal brain based on microstructure and B‐scan signal characteristics. In conjunction with the rapid image acquisition rates of SD‐OCT, this technology carries the potential of a novel intraoperative imaging tool for the detection of residual tumor and guidance of neurosurgical tumor resections. Lasers Surg. Med. 38:588–597, 2006. © 2006 Wiley‐Liss, Inc.
Development and apoptosis of pre‐implantation porcine nuclear transfer embryos activated with different combination of chemicals
Authors: Im Gi‐Sun , Seo Jin‐Sung , Hwang In‐Sun , Kim Dong‐Hoon , Kim Se‐Woong , Yang Byoung‐Chul , Yang Boh‐Suk , Lai Liangxue , Prather Randall S.
Published: May 2006

Artificial activation of oocytes is a pre‐requisite for successful cloning by nuclear transfer (NT). This study investigated effect of different combination of activation chemicals such as electric pulse (E), thimerosal (Thi) + dithiothreitol (DTT), 6‐dimethylaminopurine (6‐DMAP), or cycloheximide (CH) on the developmental ability and the frequency of apoptosis of porcine NT embryos during the culture in vitro. NT embryos activated with chemicals showed significantly higher developmental rate to blastocyst stage compared to embryos activated with E alone (21.5%–26.6% vs. 15.7%, respectively). Of chemicals, Thi + DTT supported higher development to blastocyst stage as compared to 6‐DMAP or CH (26.6% vs. 21.5%–23.4%, respectively). Apoptosis of NT embryos were analyzed by using a terminal deoxynucleatidyl transferase‐mediated deoxyuridine 5‐triphosphate nick‐end labeling (TUNEL) assay. The onset of apoptosis of embryos activated E alone was on Day 4, whereas embryos activated with chemicals showed apoptosis on Day 3 post‐activation NT embryos exposed to chemicals for activation had higher frequency of apoptosis compared to that of embryos exposed to E alone from Day 3 to Day 7 during the culture. In conclusion, this study shows that chemical activation after fusion could increase not only the developmental ability of porcine NT embryos but also the mean cell number with an increased ratio of inner cell mass (ICM) to trophectoderm (TE) cells. However, the chemical activation also could increase the frequency of apoptosis and induced apoptosis earlier in porcine NT embryos. Mol. Reprod. Dev. 1094–1101, 2006. © 2006 Wiley‐Liss, Inc.
Validation of 16S rDNA sequencing in microdissected bowel biopsies from Crohn's disease patients to assess bacterial flora diversity
Authors: De Hertogh G , Aerssens J , de Hoogt R , Peeters P , Verhasselt P , Van Eyken P , Ectors N , Vermeire S , Rutgeerts P , Coulie B , Geboes K
Published: May 2006

The bowel flora is implicated in Crohn's disease (CD) pathogenesis but its precise role is still unclear. Several non‐mutually exclusive hypotheses have been proposed: an unidentified persistent pathogen; excessive bacterial translocation; an immune system abnormality in response to normal bacteria; or a breakdown in the balance between protective and harmful bacteria. These hypotheses can be tested by identifying bacteria in specific microscopic bowel structures or lesions. The present paper describes a novel technique to assess bacterial flora diversity in bowel biopsies, by combining laser capture microdissection with broad‐range 16S rDNA sequencing. Fifty‐four samples comprising histologically normal and pathological mucosa, MALT, ulcers, submucosal lymphangiectasias, epithelioid granulomas, and lymph nodes were microdissected out of 30 bowel biopsies from five CD patients. Bacterial 16S rDNA was successfully amplified by PCR in all samples, and PCR products from 15 samples were selected for cloning and sequence analysis. A total of 729 bacterial DNA sequences were analysed, which could be attributed to six different phyla (Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, Fusobacteria, and Planctomycetes). DNA from typical bowel bacteria (Enterobacteriaceae, Clostridiales, Bacteroidetes, Fusobacteria) was detected in all microdissected areas. It was thus convincingly demonstrated that 16S rDNA sequencing can be combined with microdissection to study the bowel flora. However, no specific persistent pathogen causal for CD was identified. The results suggest that Enterobacteriaceae may initiate or colonize ulcers in CD. Translocation of bacteria through established mucosal lesions or as a result of increased permeability may be involved in the evolution towards chronic inflammation and in the establishment of persistent lesions. Further study is needed to confirm these preliminary findings. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Synthesis and characterization of biodegradable A–B–A triblock copolymers containing poly(ϵ‐caprolactone) A blocks and poly(trans‐4‐hydroxy‐L‐proline) B blocks
Authors: Lee Ren‐Shen , Lin Zhe‐Kuan , Yang Jen‐Ming , Lin Feng‐Huei
Published: May 2006

Novel, biodegradable poly(ϵ‐caprolactone)‐block‐poly(trans‐4‐hydroxy‐N‐benzyloxycarbonyl‐L‐proline)‐block‐poly(ϵ‐caprolactone) triblock copolymers were synthesized by ring‐opening polymerization from dihydroxyl‐terminated macroinitiator poly(trans‐4‐hydroxy‐N‐benzyloxycarbonyl‐L‐proline) (PHpr) and ϵ‐caprolactone (ϵ‐CL) with stannous octoate as the catalyst. The molecular weights were characterized with gel permeation chromatography and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. With an increase in the contents of ϵ‐CL incorporated into the copolymers, a decrease in the glass‐transition temperature (Tg) was observed. The Tg values of copoly(4‐phenyl‐ϵ‐caprolactone) and copoly(4‐methyl‐ϵ‐caprolactone) were higher than Tg of copoly(ϵ‐caprolactone). Their micellar characteristics in an aqueous phase were investigated with fluorescence spectroscopy, dynamic light scattering, and transmission electron microscopy. The block copolymers formed micelles in the aqueous phase with critical micelle concentrations in the range of 1.00–1.36 mg L−1. With higher molecular weights and hydrophobic components in the copolymers, a higher critical micelle concentration was observed. As the feed weight ratio of antitriptyline hydrochloride (AM) to the polymer increased, the drug loading increased. The micelles exhibited a spherical shape, and the average size was less than 250 nm. The in vitro hydrolytic degradation and controlled drug release properties of the triblock copolymers were also investigated. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4268–4280, 2006
Saccadic abnormalities in psychotropic-naive obsessive–compulsive disorder without co-morbidity
Authors: van der WEE NIC J. , HARDEMAN HANS H. , RAMSEY NICK F. , RAEMAEKERS MATHIJS , VAN MEGEN HAROLD J. , DENYS DAMIAAN A. , WESTENBERG HERMAN G. , KAHN RENÉ S.
Published: May 2006

Background. Oculomotor studies have found saccadic abnormalities in obsessive–compulsive disorder (OCD), lending support for models postulating a central role for inhibition in OCD. Saccadic abnormalities in OCD may also be potential candidates for a biological marker, important for more endophenotype-oriented research. Saccadic abnormalities have not been examined in psychotropic-naive patients with OCD without co-morbidity.

Method. We compared the error rates and latencies of 14 carefully selected adult psychotropic-naive patients with OCD with no co-morbid diagnosis and 14 pairwise matched healthy controls on a fixation task, on a prosaccade task and on an antisaccade task.

Results. Patients with OCD showed normal error rates on all tasks, but latencies on the antisaccade task were significantly increased.

Conclusions. Our results indicate that patients with OCD have no gross impairment of oculomotor inhibitory capacities, but may have a disturbed capacity to deliberately initiate a saccade to an imagined target.
Observations of isolated polar cap patches by the European Incoherent Scatter (EISCAT) Svalbard and Super Dual Auroral Radar Network (SuperDARN) Finland radars
Authors: Oksavik K. , Ruohoniemi J. M. , Greenwald R. A. , Baker J. B. H. , Moen J. , Carlson H. C. , Yeoman T. K. , Lester M.
Published: May 2006

In this paper we present observations of the F region cusp ionosphere from the Super Dual Auroral Radar Network (SuperDARN) Finland and European Incoherent Scatter (EISCAT) Svalbard radars in a new joint experiment. On 16 December 2002 the EISCAT Svalbard radar was operated in a fast elevation scan along beam 9 of the SuperDARN Finland radar, giving altitude/latitude profiles of the SuperDARN Finland backscatter volume every 2 min. Combining the two independent data sets, we monitor an isolated polar cap patch of high electron density (1011.5 m−3) that slowly formed in the dark cusp ionosphere during an interval of northward interplanetary magnetic field. The patch formed on a stirred lobe cell, excluding the possibility for solar EUV ionized plasma to drift in from the south. This data set represents an unparalleled example of patch formation within the polar cap, locally by particle impact ionization. After the interplanetary magnetic field turned southward and By changed polarity, the patch started to move poleward into the polar cap. Enhanced velocity gave rise to enhanced HF backscatter power and enhanced spectral widths, consistent with gradient drift instability as the formation mechanism of HF backscatter targets.
Particles in motion: How turbulence affects plankton sedimentation from an oceanic mixed layer
Authors: Ross Oliver N.
Published: May 2006

A long‐standing question in the dynamics of oceanic surface mixed layers (SML) is whether or not turbulence inhibits the rate of sedimentation through the layer. Results from previous studies have shown that turbulence can both retard and accelerate particle settling. Here we attempt to resolve this issue by demonstrating how both results can in fact be obtained from the same turbulence model for only slightly different implementations of the experimental set‐up. Increasing turbulence will produce an increase in particle sedimentation if the SML is modelled as a homogeneous layer with a constant turbulent intensity throughout. However, if a more realistic representation of the SML is used, in which the turbulent intensity is allowed to decrease toward the base of the SML, then an increase in turbulence will lead to an increase in the residence time of particles in the SML.
Quantification of PET Studies with the Very High-Affinity Dopamine D2/D3 Receptor Ligand [11C]FLB 457: Re-Evaluation of the Validity of using a Cerebellar Reference Region
Authors: Asselin Marie-Claude , Montgomery Andrew J , Grasby Paul M , Hume Susan P
Published: May 2006

The very high-affinity position emission tomography (PET) radioligand [11C]FLB 457 was developed in order to study extrastriatal tissues, where the density of dopamine D2/D3 receptors is one to two orders of magnitude lower than in the striatum. The present study investigated the validity of using the cerebellum as a reference region. Ten healthy volunteers underwent a 90-min dynamic PET study after the bolus injection of [11C]FLB 457. The total volume of distribution ( VDt) was estimated for the thalamus, hippocampus, frontal cortex, and cerebellum using a two-tissue compartmental model with a metabolite-corrected arterial plasma input function. VDt was sensitive to co-injected stable FLB 457 in all regions, including the cerebellum. Ex vivo saturation studies were also conducted in 17 rats where the dose of stable ligand was varied over five orders of magnitude. Specific binding was estimated to account for more than half of the rat cerebellar uptake of [11C]FLB 457, questioning the latter as an estimate of nonspecific binding in human PET studies. To check whether the cerebellum is a reference region, the binding potential (BP) was calculated either from the VDt ratio or using the simplified reference tissue model (SRTM). A non-negligible density of D2/D3 receptors in the cerebellum was shown to lead to underestimation of BP as well as erroneous estimation of differential occupancies. Binging potential estimates from the SRTM were found to be sensitive to changes in cerebral blood flow, providing further evidence for caution in the use of the cerebellum as a reference region in measures of [11C]FLB 457 binding.
Fabrication of fin field-effect transistor silicon nanocrystal floating gate memory using photochemical vapor deposition
Authors: Kim Sang Soo , Cho Won-Ju , Ahn Chang-Geun , Im Kiju , Yang Jong-Heon , Baek In-Bok , Lee Seongjae , Lim Koeng Su
Published: May 2006

The fin field-effect transistor (FET) silicon nanocrystal floating gate memory using the photochemical vapor deposition and the plasma doping processes was proposed. The silicon nanocrystals with a uniform size were formed on a vertical sidewall surface of the fin channel by the photochemical vapor deposition. The plasma doping was applied to form the junctions at the sidewall of the fin source-drain extension regions with a high aspect ratio. The FinFET silicon nanocrystal floating gate memory with a gate length of 100nm was successfully fabricated and it revealed a memory effect as well as a suppressed short-channel effect.
Two-photon-induced quenching of photoluminescence in wide-gap semiconductor crystals
Authors: Torizawa Makoto , Kawata Yoshimasa
Published: May 2006

We present photoinduced quenching of photoluminescence in a wide-gap semiconductor crystal. Because the photoluminescence is excited by a two-photon process, the quenched region is spatially localized in three dimensions. We found that the photoinduced quenching had a clear threshold at 0.70MW∕cm2 of excitation intensity. Under the intensity of the threshold, photoluminescence intensity did not decrease with long exposure time. We demonstrated three-dimensional control of photoluminescence intensity distribution in a ZnSe crystal.
Optical characterization of Eu-doped β-Ga2O3 thin films
Authors: Gollakota P. , Dhawan A. , Wellenius P. , Lunardi L. M. , Muth J. F. , Saripalli Y. N. , Peng H. Y. , Everitt H. O.
Published: May 2006

Europium-doped β-Ga2O3 thin films were grown on double-side polished c-axis (0001) sapphire substrates by pulsed laser deposition at 850°C. Transmission measurements of the films revealed a sharp band edge with a band gap at 5.0eV. The films exhibited intense red emission at 611nm (2.03eV) due to the transitions from D05 to F27 levels in europium, with intensities that increased with the concentration of europium. Time-resolved photoluminescence measurements revealed a temperature-insensitive lifetime of 1.4ms, which is much longer than the lifetimes of europium luminescence observed in GaN hosts.
Suppression of field screening in nematic liquid crystals by carbon nanotubes
Authors: Chen Hui-Yu , Lee Wei
Published: May 2006

Transient currents induced by the polarity reversal of an applied dc electric field have been measured in planar-aligned nematic liquid-crystal cells. Experimental results indicate that a minute addition of carbon nanotubes as a dopant leads to a reduction of the ion concentration and thus suppresses the undesired field-screening effect. Observed simultaneously is a higher charge mobility in the doped cells in the presence of a strong field. Such increase of mobility, in comparison with that of undoped counterparts, is attributed to the parallel alignment of both the long axis of carbon nanotubes and the nematic director along the electric field.
Evaluation of log and branch barriers as post-fire rehabilitation treatments in a Mediterranean pine forest in Greece
Authors: Spanos Ioannis , Raftoyannis Yannis
Published: May 2006

After severe fires, land management authorities in Mediterranean climate regions often apply post-fire rehabilitation measures intended to minimize on-site erosion and restore vegetation cover. The aim of our study was to evaluate the effectiveness of log and branch barriers as post-fire rehabilitation treatments after a severe fire in a Pinus brutia Ten. forest near Thessaloniki, Greece. We based our comparisons on the following woody perennial plants: Anthyllis hermanniae L., Asparagus acutifolius L., Cistus creticus L., Pinus brutia Ten., Quercus coccifera L. and Sarcopoterium spinosum (L.) Spach. Five years after fire, the post-fire treatments of log and branch barriers had no positive effect on groundcover. On the contrary, we found more exposed bare soil and rocks in the south treated plots compared to the untreated plots. A higher number of pine seedlings was observed on the treated south slopes and the untreated north slope. Higher pine mortality rates were observed in the south slopes and especially in the untreated site. Pine seedling growth was not affected by post-fire treatments. The highest density of C. creticus seedlings was found in the southern untreated plot, where the highest mortality rate was also observed. The construction of log and branch barriers had an adverse effect on Q. coccifera plants and consequently on the whole burned area revegetation process. Our study showed that the post-fire treatments had a negative effect on seedling density of A. hermanniae and A. acutifolius. The slope orientation affected the revegetation process and it was more successful on the north slopes. In conclusion, our results showed that the construction of log and branch barriers was not effective in post-fire ecosystem recovery.
Laboratory fire spread analysis using visual and infrared images
Authors: Martínez-de Dios J. Ramiro , André Jorge C. , Gonçalves João C. , Arrue Begoña Ch. , Ollero Aníbal , Viegas Domingos X.
Published: May 2006

This paper presents an experimental method using computer-based image processing techniques of visual and infrared movies of a propagating fire front, taken from one or more cameras, to supply the time evolutions of the fire front shape and position, flame inclination angle, height, and base width. As secondary outputs, it also provides the fire front rate of spread and a 3D graphical model of the fire front that can be rendered from any virtual view. The method is automatic and non-intrusive, has space–time resolution close to continuum and can be run in real-time or deferred modes. It is demonstrated in simple laboratory experiments in beds of pine needles set upon an inclinable burn table, with point and linear ignitions, but can be extended to open field situations.
The
Mycobacterium tuberculosis
LipB enzyme functions as a cysteine/lysine dyad acyltransferase
Authors: Ma Qingjun , Zhao Xin , Eddine Ali Nasser , Geerlof Arie , Li Xinping , Cronan John E. , Kaufmann Stefan H. E. , Wilmanns Matthias
Published: May 2006

Lipoic acid is essential for the activation of a number of protein complexes involved in key metabolic processes. Growth of
Mycobacterium tuberculosis
relies on a pathway in which the lipoate attachment group is synthesized from an endogenously produced octanoic acid moiety. In patients with multiple-drug-resistant
M. tuberculosis
, expression of one gene from this pathway,
lipB
, encoding for octanoyl-[acyl carrier protein]-protein acyltransferase is considerably up-regulated, thus making it a potential target in the search for novel antiinfectives against tuberculosis. Here we present the crystal structure of the
M. tuberculosis
LipB protein at atomic resolution, showing an unexpected thioether-linked active-site complex with decanoic acid. We provide evidence that the transferase functions as a cysteine/lysine dyad acyltransferase, in which two invariant residues (Lys-142 and Cys-176) are likely to function as acid/base catalysts. Analysis by MS reveals that the LipB catalytic reaction proceeds by means of an internal thioesteracyl intermediate. Structural comparison of LipB with lipoate protein ligase A indicates that, despite conserved structural and sequence active-site features in the two enzymes, 4′-phosphopantetheine-bound octanoic acid recognition is a specific property of LipB.
STEREOCHEMICAL ANALYSIS OF THE SPECIFICITY OF PANCREATIC RNASE WITH POLYFORMYCIN AS SUBSTRATE: DIFFERENTIATION OF THE TRANSPHOSPHORYLATION AND HYDROLYSIS REACTIONS
Authors: Ward D. C. , Fuller W. , Reich E.
Published: May 2006

A stereochemical analysis of the substrate and inhibitor specificities of bovine pancreatic ribonuclease A is presented. A scheme is proposed in which the binding specificity for this protein-nucleic acid interaction is rationalized in terms of a simple system of H-bonds. The functional groups that govern substrate binding for transphosphorylation and hydrolysis, respectively, are considered and differentiated, and predictions are offered concerning the interaction of presumptive substrates with RNase.
NEURONAL DYNAMICS AND AXONAL FLOW, IV. BLOCKAGE OF INTRA-AXONAL ENZYME TRANSPORT BY COLCHICINE
Authors: Kreutzberg Georg W.
Published: May 2006

The fact that the nucleated center of the nerve cell is the major source of the macromolecular materials required in the maintenance and function of the whole neuron requires the operation of a steady cellulifugal convection of these supplies into and down the nerve fiber. This proximo-distal traffic has been firmly established, but the mechanisms involved in it are still poorly understood. Besides the slow (
ca
. 1 mm per day) advance of the axonal column as a whole (“axonal flow” in the strict sense), the demonstration of additional, much faster, traffic rates (up to several cm per day) calls for special conduits within the axon (“intra-axonal flow”). To test the possible role of neurotubules (average width:220 Å) in this traffic, the drug colchicine, known for its immobilizing effect on microtubules in other types of cells, was locally injected into peripheral nerves. This resulted in a major blockage of the proximo-distal movement of a test enzyme, acetylcholinesterase, into and through the injected zone, the extent of blockage varying with the applied dosage. By analogy, the neurotubules thus seem to be definitely implicated in the motile mechanism of intra-axonal transport. By contrast, the movement of a mitochondrion-associated marker enzyme, diphosphopyridine nucleotide diaphorase, was not perceptibly affected (in the submaximal dosage range), which seems to signify that the proximo-distal shift of mitochondria, for which the slow axonal flow acts as carrier, has gone on uninterruptedly. The experiments thus indicate the possibility of uncoupling the axonal and intra-axonal transport mechanisms.
ISOLATION OF ADENYL CYCLASE FROM
Escherichia coli
Authors: Tao Mariano , Lipmann Fritz
Published: May 2006

We have found a soluble cyclase, using for assay radioactively marked ATP as precursor. The reaction product was isolated by thin-layer chromatography and identified by specific degradation. After homogenization, part of the activity remained in the particulate fraction but could be easily extracted. The cyclase was concentrated 100-fold by conventional methods. The enzyme has a Mg
++
requirement and is inhibited by fluoride and inorganic pyrophosphate.
MINIMIZATION OF POLYPEPTIDE ENERGY, VI. SYSTEMATIC SEARCHES FOR LOW-ENERGY CONFORMATIONS OF DECA-L-ALANINE AND THE OCTAPEPTIDE LOOP OF RIBONUCLEASE
Authors: Gibson K. D. , Scheraga H. A.
Published: May 2006

A succession of apparent local energy minima, in which the energies decrease successively, have been located for deca-L-alanine and the octapeptide loop of ribonuclease. The lowest energy minima were approximately 40 kcal/mole lower than the highest ones. The results suggest that the computational methods used here might be of considerable use in searching for the global energy minimum of larger polypeptides.
FORMATION AND DETECTION OF RNA-DNA HYBRID MOLECULES IN CYTOLOGICAL PREPARATIONS
Authors: Gall Joseph G. , Pardue Mary Lou
Published: May 2006

A technique is described for forming molecular hybrids between RNA in solution and the DNA of intact cytological preparations. Cells in a conventional tissue squash are immobilized under a thin layer of agar. Next they are treated with alkali to denature the DNA and then incubated with tritium-labeled RNA. The hybrids are detected by autoradiography. The technique is illustrated by the hybridization of ribosomal RNA to the amplified ribosomal genes in oocytes of the toad
Xenopus
. A low level of gene amplification was also detected in premeiotic nuclei (oogonia).
THE INFLUENCE OF SHORT-RANGE INTERACTIONS ON PROTEIN CONFORMATION, III. DIPEPTIDE DISTRIBUTIONS IN PROTEINS OF KNOWN SEQUENCE AND STRUCTURE
Authors: Kotelchuck D. , Dygert M. , Scheraga H. A.
Published: May 2006

A statistical analysis is made of the distribution into α-helical and non-α-helical regions of the various dipeptide types appearing in a sample of seven proteins of known sequence and structure. By considering as a group all dipeptide types occurring at a given location relative to the reported helix-coil boundaries and examining the percentage of cases in which these appear in non-α-helical regions
throughout the protein sample
, we find a sharp change in the nature of the observed dipeptide types when the helix-coil boundary is crossed. Furthermore, we find that dipeptide types which occur in the coil region near the C-terminal end of helical segments are non-α-helical in almost 90 per cent of the cases in which they appear throughout the sample. No similar effect is found in the coil region near the N-terminal end of helical segments. These results give evidence for the importance of short-range interactions in determining protein conformation. They are also consistent with predictions based on a model for helix formation given in the second paper of this series.
1
DYSFUNCTIONAL SPERM PRODUCTION IN
Drosophila melanogaster
MALES HOMOZYGOUS FOR THE SEGREGATION DISTORTER ELEMENTS
Authors: Hartl Daniel L.
Published: May 2006

Drosophila
males heterozygous for the segregation distorter chromosome show a reduction in fecundity which is correlated with the degree of distortion of their segregation ratio. When males are made homozygous for the segregation distorter elements, their fecundity is lowered to just that extent expected if each
SD
were independently causing the sperms carrying the other to dysfunction. In three cases tested,
Sd Ac/Ac, Sd Ac/Sd Ac
, and
Sd Ac St/Sd Ac St
, the fecundity of the males is consistent with the dysfunction model, whereas the females are normal.

The
Sd Ac St/Sd Ac St
males are almost completely sterile. They do produce sperms, however, which are motile and which look morphologically normal in the phase contrast microscope. They are transferred to the female during copulation and are stored in apparently normal numbers in the seminal receptacle and spermathecae.
In vitro
DIFFERENTIATION OF A MOUSE NEUROBLASTOMA
Authors: Schubert David , Humphreys Susie , Baroni Carlo , Cohn Melvin
Published: May 2006

Mouse tumor C1300 has been established in tissue culture. The cells have a round cell morphology in both the subcutaneous tumor and in suspension culture. However, when given a surface on which to attach, they send out processes up to 3 mm in length and assume the morphology of mature neurons. The attached cells are stained by the Bodian silver procedure for neurons, whereas the cells grown in suspension are not. Electron microscopy reveals that the attached cells contain neurofilaments, neurotubules, and densecore vesicles indicative of nerve fibers. Both free-floating and attached cells have tyrosine hydroxylase activity characteristic of sympathetic nervous tissue. Apparently cell attachment can induce morphological differentiation from an anaplastic round cell to a cell which has many properties of a mature neuron.
MOUSE LEUKEMIA VIRUS: “SPONTANEOUS” RELEASE BY MOUSE EMBRYO CELLS AFTER LONG-TERM
in vitro
CULTIVATION
Authors: Aaronson Stuart A. , Hartley Janet W. , Todaro George J.
Published: May 2006

BALB/c mouse embryo cells maintained in tissue culture on a schedule of rapid transfer at high cell density develop into tumorigenic lines that have lost contact inhibition of cell division. After several months in culture, certain of these lines begin to release mouse leukemia virus. This virus has properties indistinguishable from those of virus found in adult BALB/c mice. The evidence presented here demonstrates that the murine leukemia virus genome must be present in the original embryo cultures. The possibility that the genetic information for making murine leukemia virus is present in a repressed form in every mouse embryo cell is discussed.
HYDROCARBON DISTRIBUTION OF ALGAE AND BACTERIA, AND MICROBIOLOGICAL ACTIVITY IN SEDIMENTS
Authors: Han Jerry , Calvin Melvin
Published: May 2006

The chemical taxonomic relationship of microorganisms has been studied through the hydrocarbon fraction of their chemical constituents. The diagenesis and biological transformations of some hydrocarbons in sediments is suggested, as a result of this information.
MOLECULAR HYBRIDIZATION OF RADIOACTIVE DNA TO THE DNA OF CYTOLOGICAL PREPARATIONS
Authors: Pardue Mary Lou , Gall Joseph G.
Published: May 2006

A method is presented for detecting the cellular location of specific DNA fractions. The technique involves the hybridization of a radioactive test DNA in solution to the stationary DNA of a cytological preparation. Sites of DNA binding are then detected by autoradiography. Experiments with DNA of the toad
Xenopus
are described.
PHOTOREGULATION OF BIOLOGICAL ACTIVITY BY PHOTOCHROMIC REAGENTS, III. PHOTOREGULATION OF BIOELECTRICITY BY ACETYLCHOLINE RECEPTOR INHIBITORS
Authors: Deal Walter J. , Erlanger Bernard F. , Nachmansohn David
Published: May 2006

The photochromic compounds
N-p
-phenylazophenyl-
N
-phenylcarbamylcholine chloride and
p
-phenylazophenyltrimethylammonium chloride inhibit the carbamylcholine-produced depolarization of the excitable membrane of the monocellular electroplax preparation of
Electrophorus
. The
trans
isomer of each predominates in the light of a photoflood (420 mμ) lamp; they are stronger inhibitors than the
cis
isomers, which predominate under ultraviolet (320 mμ) irradiation. The potential difference across the excitable membrane may be photoregulated by exposing an electroplax in the presence of a solution of carbamylcholine and either of the two compounds to light of appropriate wavelengths, since light shifts the
cis-trans
equilibrium. The system may be considered as a model illustrating how one may link a
cis-trans
isomerization, the first step in the initiation of a visual impulse, with substantial changes (20-30 mv) in the potential difference across an excitable membrane.
THE ROLE OF RIBOSOMAL CONFORMATION IN PROTEIN BIOSYNTHESIS: THE STREPTOMYCIN-RIBOSOME INTERACTION
Authors: Sherman Michael I. , Simpson Melvin V.
Published: May 2006

The role played by ribosomal conformation in codon-anticodon recognition has been studied using streptomycin as a probe, inasmuch as streptomycin is known to cause misreading of the genetic code. Changes in ribosomal structure have been followed by the method of hydrogen-tritium exchange. The results show that streptomycin induces two types of change in the hydrogen exchange pattern. At low molar ratios of streptomycin to ribosomes, a stimulation of the hydrogen exchange rate (“loosening” of ribosomal structure) is observed, with a small inhibition of polypeptide synthesis. As the streptomycin: ribosome ratio is increased, a maximum exchange rate is reached, after which the rate decreases (“tightening” of structure); in this region, inhibition of peptide synthesis increases sharply, and misreading of the code begins. None of these effects is observed with streptomycin-resistant ribosomes.
Selective Elimination of the Exonuclease Activity of the Deoxyribonucleic Acid Polymerase from
Escherichia coli
B by Limited Proteolysis
Authors: Klenow H. , Henningsen I.
Published: May 2006

Purification of DNA polymerase from
E. coli
B has in two cases each time led to the isolation of two separate polymerase activities, enzyme A and enzyme B. Enzyme A was in contrast to enzyme B almost completely devoid of exonuclease activity. Each of the two enzymes yielded a single symmetrical activity peak in gel filtration chromatograms. From the elution volumes the molecular weights were estimated to be about 70,000 for enzyme A and about 150,000 for enzyme B.

Treatment of enzyme B with subtilisin led to an increase of about 30 per cent of the polymerase activity while the exonuclease activity almost completely disappeared. The product of the subtilisin treatment (enzyme C) gave rise to a single symmetrical polymerase activity peak in a gel filtration chromatogram. The elution volume was identical to that obtained with enzyme A. It is concluded that enzyme A and enzyme C are formed by limited proteolysis of enzyme B.