bluuebunny/crossref_metadata_2025 huggingface dataset:
Eine Hand voll Technik mit Fingerspitzengefühl
Authors: Meuser Marcell , Murrenhoff Hubertus
Published: December 2003

Ob als Prothese oder Roboterhand — Künstliche Hände werden für eine Vielzahl von Anwendungen benötigt. Eine neue, mit Druckluft betriebene Roboterhand zeichnet sich durch besondere Greif‐ und Haltemöglichkeiten aus
Precursor‐Directed Biosynthesis: Stereospecificity for Branched‐Chain Diketides of the β‐Ketoacyl‐ACP Synthase Domain 2 of 6‐Deoxyerythronolide B Synthase
Authors: Kinoshita Kenji , Khosla Chaitan , Cane David E.
Published: December 2003

Modular polyketide synthases such as 6‐deoxyerythronolide B synthase (DEBS) catalyze the biosynthesis of structurally complex natural products. Streptomyces coelicolor CH999/pJRJ2 harbors a plasmid encoding DEBS(KS10), a mutant form of 6‐deoxyerythronolide B synthase that is blocked in the formation of 6‐deoxyerythronolide B (1, 6‐dEB) due to a mutation in the active site of the ketosynthase (KS1) domain that normally catalyzes the first polyketide chain‐elongation step of 6‐dEB biosynthesis. Administration of (2S,3R,4S)‐ and (2S,3R,4R)‐3‐hydroxy‐2,4‐dimethylhexanoic acid N‐acetylcysteamine (SNAC) thioesters (= S‐[2‐(acetylamino)ethyl] (2S,3R,4S)‐ and (2S,3R,4R)‐3‐hydroxy‐2,4‐dimethylhexanethioates) 3 and 4 in separate experiments to cultures of Streptomyces coelicolor CH999/pJRJ2 led to production of the corresponding (14S)‐ and (14R)‐14‐methyl analogues of 6‐dEB, 10 and 11, respectively. Unexpectedly, when a 3 : 2 mixture of 4 and 3 was fed under the same conditions, exclusively branched‐chain macrolactone 11 was isolated. In similar experiments, feeding of 3 and 4 to S. coelicolor CH999/pCK16, an engineered strain harboring DEBS1+TE(KS10), resulted in formation of the branched‐chain triketide lactones 13 and 14, while feeding of the 3 : 2 mixture of 4 and 3 gave exclusively 14. The biochemical basis for this stereochemical discrimination was established by using purified DEBS module 2+TE to determine the steady‐state kinetic parameters for 3 and 4, with the kcat/KM for 4 shown to be sevenfold greater than that of 3.
Cobalamin‐Dependent and Cobalamin‐Independent Methionine Synthases: Are There Two Solutions to the Same Chemical Problem?
Authors: Matthews Rowena G. , Smith April E. , Zhou Zhaohui S. , Taurog Rebecca E. , Bandarian Vahe , Evans John C. , Ludwig Martha
Published: December 2003

Two enzymes in Escherichia coli, cobalamin‐independent methionine synthase (MetE) and cobalamin‐dependent methionine synthase (MetH), catalyze the conversion of homocysteine (Hcy) to methionine using N(5)‐methyltetrahydrofolate (CH3‐H4folate) as the Me donor. Despite the absence of sequence homology, these enzymes employ very similar catalytic strategies. In each case, the pKa for the SH group of Hcy is lowered by coordination to Zn2+, which increases the concentration of the reactive thiolate at neutral pH. In each case, activation of CH3‐H4folate appears to involve protonation at N(5). CH3‐H4folate remains unprotonated in binary E⋅CH3‐H4folate complexes, and protonation occurs only in the ternary E⋅CH3‐H4folate⋅Hcy complex in MetE, or in the ternary E⋅CH3‐H4folate⋅cob(I)alamin complex in MetH. Surprisingly, the similarities are proposed to extend to the structures of these two unrelated enzymes. The structure of a homologue of the Hcy‐binding region of MetH, betainehomocysteine methyltransferase, has been determined. A search of the three‐dimensional‐structure data base by means of the structure‐comparison program DALI indicates similarity of the BHMT structure with that of uroporphyrin decarboxylase (UroD), a homologue of the MT2‐A and MT2‐M proteins from Archaea, which catalyze Me transfers from methylcorrinoids to coenzyme M and share the Zn‐binding scaffold of MetE. Here, we present a model for the Zn binding site of MetE, obtained by grafting the Zn ligands of MT2‐A onto the structure of UroD.
Synthesis of Selectively 15N‐Labeled 2′‐O‐{[(Triisopropylsilyl)oxy]methyl}(=tom)‐Protected Ribonucleoside Phosphoramidites and Their Incorporation into a Bistable 32Mer RNA Sequence
Authors: Wenter Philipp , Pitsch Stefan
Published: December 2003

We present optimized reaction conditions for the conversion of 2′‐O‐{[(triisopropylsilyl)oxy]methyl}(=tom) protected uridine and adenosine nucleosides into the corresponding protected (3‐15N)‐labeled uridine and cytidine and (1‐15N)‐labeled adenosine and guanosine nucleosides 4, 6, 12, and 18, respectively (Schemes 1–4). On a DNA synthesizer, the resulting 15N‐labeled 2′‐O‐tom‐protected phosphoramidite building blocks 19–22 were efficiently incorporated into five selected positions of a bistable 32mer RNA sequence 23 (known to adopt two different structures) (Fig. 1). By 2D‐HSQC and HNN‐COSY experiments in H2O/D2O 9 : 1, the 15N‐signals of all base‐paired 15N‐labeled nucleotides could be identified and attributed to one of the two coexisting structures of 23.
Automated Synthesis of Oligosaccharides
Authors: Palmacci Emma R. , Plante Obadiah J. , Hewitt Michael C. , Seeberger Peter H.
Published: December 2003

The chemical synthesis of oligosaccharides with an automated solid‐phase synthesizer is described. An octenediol linker served to attach the growing oligosaccharide chain to the solid support, and the desired structures were cleaved from the support via olefin metathesis to afford a pentenyl glycoside. The automated syntheses of several important carbohydrates, including a pentarhamnoside, a proteoglycan linkage‐region tetrasaccharide, a phytoalexin elicitor dodecasaccharide, and a branched Leishmania lipophosphoglycan tetrasaccharide, were accomplished in higher overall yield and ca. 20 times faster than with solution‐phase methods.
Stereocontrolled Synthesis of (2R,3S)‐2‐Methylisocitrate, a Central Intermediate in the Methylcitrate Cycle
Authors: Darley Dan J. , Selmer Thorsten , Clegg William , Harrington Ross W. , Buckel Wolfgang , Golding Bernard T.
Published: December 2003

2‐Methylisocitrate (=3‐hydroxybutane‐1,2,3‐tricarboxylic acid) is an intermediate in the oxidation of propanoate to pyruvate (=2‐oxopropanoate) via the methylcitrate cycle in both bacteria and fungi (Scheme 1). Stereocontrolled syntheses of (2R,3S)‐ and (2S,3R)‐2‐methylisocitrate (98% e.e.) were achieved starting from (R)‐ and (S)‐lactic acid (=(2R)‐ and (2S)‐2‐hydroxypropanoic acid), respectively. The dispiroketal (6S,7S,15R)‐15‐methyl‐1,8,13,16‐tetraoxadispiro[5.0.5.4]hexadecan‐14‐one (2a) derived from (R)‐lactic acid was deprotonated with lithium diisopropylamide to give a carbanion that was condensed with diethyl fumarate (Scheme 3). The configuration of the adduct diethyl (2S)‐2‐[(6S,7S,14R)‐14‐methyl‐15‐oxo‐1,8,13,16‐tetraoxadispiro[5.0.5.4]hexadec‐14‐yl]butanedioate (3a) was assigned by consideration of possible transition states for the fumarate condensation (cf. Scheme 2), and this was confirmed by a crystal‐structure analysis. The adduct was subjected to acid hydrolysis to afford the lactone 4a of (2R,3S)‐2‐methylisocitrate and hence (2R,3S)‐2‐methylisocitrate. Similarly, (S)‐lactic acid led to (2S,3R)‐2‐methylisocitrate. Comparison of 2‐methylisocitrate produced enzymatically with the synthetic enantiomers established that the biologically active isomer is (2R,3S)‐2‐methylisocitrate.
Achiral Calcium‐Oxalate Crystals with Chiral Morphology from the Leaves of Some Solanacea Plants
Authors: Levy‐Lior Avital , Weiner Steve , Addadi Lia
Published: December 2003

The leaves of some plants, particularly among the Solanacea, contain crystals of calcium oxalate with a peculiar chiral pseudo‐tetrahedral morphology, even though the calcium oxalate crystal structure is centrosymmetric, hence achiral. We studied the morphology of these crystals extracted from the leaves of three Solanacea plants: the potato, the hot pepper, and a species of wild Solanum. The crystal morphology was the same in all three species. Based on the examination of more than 100 crystals from each plant, we showed that the crystal morphology is chiral with invariant chirality. We suggest that morphological chirality is induced by macromolecules during nucleation from a specific, genetically encoded crystal plane, and is further established during subsequent controlled crystal growth. This is one of few examples where it is possible to deduce a molecular mechanism for biologically induced breaking of morphological symmetry in organisms. A very high level of recognition is required by the macromolecules to allow them to distinguish between symmetry‐related crystal planes. It is also surprising that this finely controlled mechanism of crystal formation, including the chiral morphology, has been conserved during evolution.
Molecular Shape and Intermolecular Liaison: Hydrocarbons and Fluorocarbons
Authors: Dunitz Jack D. , Gavezzotti Angelo , Schweizer W. Bernd
Published: December 2003

Whereas aliphatic hydrocarbon/fluorocarbon mixtures show mutual ‘phobicity’ (e.g., positive deviations from Raoult's Law), their aromatic counterparts show the opposite behavior. Hexafluorobenzene forms co‐crystals with many aromatic hydrocarbons, but co‐crystals are unknown in the aliphatic series. This remarkable contrast between the behaviors of aliphatic and aromatic hydrocarbon/fluorocarbon mixtures calls for explanation, and we attempt to provide one in terms of the difference in overall molecular shape – disk vs. cylinder – using the new PIXEL method for calculating intermolecular energies.
Peripheral nerve regeneration using acellular nerve grafts
Authors: Kim Byung‐Soo , Yoo James J. , Atala Anthony
Published: December 2003

Long gap peripheral nerve injuries usually require a graft to facilitate axonal regeneration into the distal nerve stump. The use of autografts is often limited because of graft availability and donor‐site morbidity. We investigated whether acellular nerve allografts would provide an appropriate channel for the promotion and induction of sciatic nerve regeneration in rats. Axons sprouted from the proximal portion and reached the distal portion in the 1 cm‐long grafts by 1 month. The number of axons in the regenerated nerves was similar to that of normal nerves at 1 month. Loading the grafts with βNGF and VEGF increased the number and mean diameter of axons and neovascularization in the regenerated nerves at 1 month. The motor conduction velocity increased over time and reached 63 ± 10% of that of normal nerves at 6 months. The nerve injuries treated with the acellular grafts had a significant improvement in motor, nociception, and proprioception function compared to untreated nerves. The results from this study suggest that acellular nerve allografts may be a useful biomaterial for functional peripheral nerve regeneration. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 201–209, 2004
Attachment and spreading of fibroblasts on an RGD peptide–modified injectable hyaluronan hydrogel
Authors: Shu Xiao Zheng , Ghosh Kaustabh , Liu Yanchun , Palumbo Fabio S. , Luo Yi , Clark Richard A. , Prestwich Glenn D.
Published: December 2003

Hyaluronan (HA) hydrogels resist attachment and spreading of fibroblasts and most other mammalian cell types. A thiol‐modified HA (3,3′‐dithiobis(propanoic dihydrazide) [HA‐DTPH]) was modified with peptides containing the Arg‐Gly‐Asp (RGD) sequence and then crosslinked with polyethylene glycol (PEG) diacrylate (PEGDA) to create a biomaterial that supported cell attachment, spreading, and proliferation. The hydrogels were evaluated in vitro and in vivo in three assay systems. First, the behavior of human and murine fibroblasts on the surface of the hydrogels was evaluated. The concentration and structure of the RGD peptides and the length of the PEG spacer influenced cell attachment and spreading. Second, murine fibroblasts were seeded into HA‐DTPH solutions and encapsulated via in situ crosslinking with or without bound RGD peptides. Cells remained viable and proliferated within the hydrogel for 15 days in vitro. Although the RGD peptides significantly enhanced cell proliferation on the hydrogel surface, the cell proliferation inside the hydrogel in vitro was increased only modestly. Third, HA‐DTPH/PEGDA/peptide hydrogels were evaluated as injectable tissue engineering materials in vivo. A suspension of murine fibroblasts in HA‐DTPH was crosslinked using PEGDA plus PEGDA peptide, and the viscous, gelling mixture was injected subcutaneously into the flanks of nude mice; gels formed in vivo following injection. After 4 weeks, growth of new fibrous tissue had been accelerated by the sense RGD peptides. Thus, attachment, spreading, and proliferation of cells is dramatically enhanced on RGD‐modified surfaces but only modestly accelerated in vivo tissue formation. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 365–375, 2004
Production of microspheres based on hydrophobically associating alginate derivatives by dispersion/gelation in aqueous sodium chloride solutions
Authors: Leonard M. , Rastello de Boisseson M. , Hubert P. , Dellacherie E.
Published: December 2003

A new “all aqueous” procedure for the preparation of stable polysaccharide microparticles was developed. The method consists of dispersing a water solution of an amphiphilic alginate derivative (in the current work, alginate substituted with low amounts of dodecyl chains) first fluidified under mechanical stress, into an NaCl solution. The procedure exploits the ability of amphiphilic associative derivatives to form strong hydrogels in the presence of nonchaotropic salts and their shear‐thinning/thixotropic properties. Depending on the experimental conditions, the size of the microparticles can be varied from 10 μm to several hundred micrometers. Their mechanical properties can eventually be reinforced by addition of low concentrations of calcium chloride. The resulting microparticles exhibit a better stability than that of plain Ca2+‐alginate particles, as they are not disrupted when nongelling cations or calcium‐sequestering agents are added to the solution. In addition, the particles can be easily redispersed after being centrifuged or freeze‐dried. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 335–342, 2004
Growth behavior, matrix production, and gene expression of human osteoblasts in defined cylindrical titanium channels
Authors: Frosch Karl‐Heinz , Barvencik Florian , Viereck Volker , Lohmann Christoph H. , Dresing Klaus , Breme Jürgen , Brunner Edgar , Stürmer Klaus Michael
Published: December 2003

The purpose of the current study was to investigate the effect of different diameters of cylindrical titanium channels on human osteoblasts. Titanium samples having continuous drill channels with diameters of 300, 400, 500, 600, and 1000 μm were put into osteoblast cell cultures that were isolated from 12 adult human trauma patients. Cell migration into the drill channels was investigated by transmitted‐light microscopy. The DNA content in the drill channels was measured photometrically, collagen type I production was analyzed by enzyme‐linked immunosorbent assay (ELISA) and osteocalcin gene expression by reverse transcriptase–polymerase chain reaction (RT‐PCR). Formation of mineralized tissue was assessed by microradiographs of histological sections. Within 20 days, cells grew an average of 838 μm (±128 μm) into the drill channels with a diameter of 600 μm and were significantly faster (p < 0.05) than in all other channels. Cells produced significantly more osteocalcin messenger RNA (mRNA) in 600‐μm channels (p < 0.05) than they did in 1000‐μm channels and demonstrated the highest osteogenic differentiation. The channel diameter did not influence collagen type I production. The highest cell density was found in 300‐μm channels (p < 0.05). The DNA content of the channels linearly decreased with increasing channel diameters. After 40 days of culture, the proportion of mineralized tissue at the mouth section amounted to 6% in 300‐μm channels and to 9–11% in 400–600‐μm channels. In 1000‐μm channels, only traces of mineralization were detected. Our data suggest that the diameter of cylindrical titanium channels has a significant effect on migration, gene expression, and mineralization of human osteoblasts. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 325–334, 2004
Primary human marrow stromal cells and Saos‐2 osteosarcoma cells use different mechanisms to adhere to hydroxylapatite
Authors: Kilpadi Krista L. , Sawyer Amber A. , Prince Charles W. , Chang Pi‐Ling , Bellis Susan L.
Published: December 2003

One important step in bone formation on hard tissue implants is adhesion of osteoblast precursors to the implant surface. In this study, we used function‐blocking antibodies against integrin subunits to characterize the mechanisms used by human marrow stromal cells and Saos‐2 osteosarcoma cells to adhere to protein‐coated hydroxylapatite (HA). We found that Saos‐2 use both α5‐ and αv‐containing integrins, whereas stromal cells use αv‐containing integrins but not α5‐containing integrins, despite the presence of α5‐containing integrins on cell surfaces. On the basis of this difference, we examined binding of these cell types to HA coated with fibronectin (FN) or vitronectin (VN), to determine whether these ligands for α5 and αv integrins could enhance the numbers or morphology of cells adhered to them. We also examined the adhesion of cells to HA coated with RGD peptides designed to bind to FN or VN receptors. Morphology and number of adherent stromal cells were markedly enhanced on serum‐coated surfaces compared with FN or VN alone, whereas, surprisingly, Saos‐2 cells failed to spread on serum‐coated HA and displayed superior spreading and stress fiber formation on VN‐coated HA. Collectively, these results have important implications for the design of protein coatings to enhance the performance of HA implants. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 273–285, 2004
Fibroblast attachment to smooth and microtextured PET and thin cp‐Ti films
Authors: Jain Rakhi , von Recum Andreas F.
Published: December 2003

Improving the biological performance of engineered implants apposing interfacing tissues is a critical issue in Biomaterials Science and Engineering. Micromotion at the soft tissue–implant interface has been shown to sustain an inflammatory response. To eliminate micromotion, it is desirable to promote cellular and extracellular matrix adhesion to the implant surface. Surfaces are modified topographically or chemically to effect cellular adhesion and to influence cellular interactions and function. Previous studies have identified the specific topographical characteristics that appear to elicit cellular attachment. This in vitro study compares the independent effects of surface chemistry and topography on fibroblast‐test specimen proximity. Titanium (Ti) was sputter‐coated in stepwise, increasing thickness (20–350 nm) onto a series of either smooth or microtextured polyethylene terephthalate (PET), resulting in a stepwise change from a PET surface to a Ti surface. The series was evaluated in a 3‐day fibroblast culture with transmission electron microscopy (TEM) for cell–test specimen proximity. Fibroblast proximity to the coverslip surface increases, as the Ti thickness increases, on either smooth or textured test specimens. Furthermore, fibroblasts were firmly attached to the ridge tops on the coated textured test specimens. Therefore, fibroblast apposition is strongly enhanced by microtextured surfaces and Ti rather than smooth surfaces and PET. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 296–304, 2004
Pitfalls in the detection of lipid vectors in neural cell culture and in brain tissue
Authors: Rizk T. , Montero‐Menei C. , Jollivet C. , Benoit J. P. , Menei P.
Published: December 2003

Lipid particles (liposomes and lipid‐coated microbubbles) are currently studied as vectors for drug delivery to the central nervous system. The visualization of these particles is usually based on their labeling with a lipophilic fluorescent dye (3,3′‐dioctadecycloxacarbocyanine perchlorate) or staining with Oil Red O. The purpose of this article was to highlight the difficulties and pitfalls encountered with the use of these techniques in the detection of lipid particles in neural cell cultures and in brain tissue. In vitro and in vivo studies were conducted on different neural cell cultures (rat and human tumors, microglial cells) and animal models of brain lesion (lipopolysaccharide and quinolinic acid‐induced lesion, induced brain tumor). The cells or brain slices were observed with optical microscopy after staining with Oil Red O, fluorescent microscopy, or scanning electron microscopy. Intra and extracytoplasmic lipid particles (stained with Oil Red O or autofluorescent or visualized by scanning electron microscopy) were naturally found in the cells and tissues studied. Intracytoplasmic lipid microparticles were present in tumoral and microglial cells. These lipid microparticles were also observed with some extracytoplasmic lipid droplets in the induced brain lesions. These images could be misinterpreted as lipid vectors if the cells or animals would have been treated with such a vector. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 360–364, 2004
Plasmapheresis for hyperlipidemic pancreatitis
Authors: Yeh Jiann‐Horng , Chen Jui‐Hao , Chiu Hou‐Chang
Published: December 2003

Patients with triglyceride levels over 1,000 mg/dl are at high risk of developing acute pancreatitis. This study aimed to determine the effectiveness of plasma exchange (PE) in reducing triglyceride levels during an acute attack of hyperlipidemic pancreatitis (HLP). A total of 17 hypertriglyceridemic patients with the complication of acute pancreatitis received one course of PE treatment for one or two consecutive sessions. The respective mean removal rates during a single PE for triglyceride, cholesterol, amylase, and lipase were 66.3, 62.1, 70.0, and 84.8%, respectively. An additional one exchange increased the removal rate to 83.3, 66.2, 85.5, and 87.0%, respectively. For the two‐sessions of treatment, the removal rates were higher for triglyceride (P = 0.0015) and amylase with a borderline statistical significance (P = 0.0641). Better triglyceride clearance correlated well with lower levels of transmembrane pressure (TMP) at 90 minutes after PE (r2 = 0.5782, P = 0.0010) and shorter plasmapheresis duration (r2 = 0.2241, P = 0.0427). Thirteen of seventeen patients (76.5%) recovered completely, eight patients in a single‐session, and five in two‐sessions. Two patients developed intra‐abdominal abscess, necessitating surgical drainage and two patients died due to both septic shock and multi‐organ failure. No significant predictor of clinical outcome was identified. In summary, PE treatment is an effective method to clear lipids and enzymes from plasma in a single session for most HLP patients. A greater extraction of triglyceride would result in a reduced TMP and a shorter duration of PE treatment. J. Clin. Apheresis 18:181–185, 2003. © 2003 Wiley‐Liss, Inc.
Extracorporeal double filtration plasmapheresis in acute atherothrombotic brain infarction caused by major artery occlusive lesion
Authors: Hasegawa Yasuhiro , Tagaya Masafumi , Fujimoto Shigeru , Hayashida Kohei , Yamaguchi Takenori , Minematsu Kazuo
Published: December 2003

Extracorporeal double filtration plasmapheresis (EDFP) can quickly lower plasma viscosity and fibrinogen concentration. EDFP has the potential to improve cerebral microcirculation in acute ischemic stroke and ultimately to salvage penumbral tissue. However, no evidence is available to show that EDFP can increase cerebra blood flow (CBF). Therefore, we investigated whether EDFP could increase CBF by quantitative CBF measurements and documented the clinical effects of EDFP in acute ischemic stroke. EDFP was performed ten times in seven patients diagnosed as having acute atherothrombotic brain infarction caused by major artery occlusive lesion. They also fulfilled one of the following entry criteria: 1) diffusion/perfusion mismatch demonstrated by MRI on admission; 2) a hemispheric syndrome, but only a small lesion on diffusion weighted MRI (<25% of MCA territory); or 3) progressing stroke. Exclusion criteria were 1) contraindication of heparin or 2) spontaneous improvement of symptoms. Time from stroke onset to EDFP varied from 5 hr to 7 days. Plasma viscosity was quickly lowered by EDFP without affecting RBC counts, Hb, or Hct in all patients. Positron emission tomography (PET) with 15‐O labeled H2O measurements revealed a significant CBF increase from 36.4±8.3 ml/100 g/min to 40.7±6.8 ml/100 g/min in the affected hemisphere (P=0.048). Definite CBF improvement was also demonstrated by single photon emission computed tomography (SPECT) in one of two patients who had severe stenosis of the middle cerebral artery. Furthermore, this patient showed remarkable improvement of hemiplegia immediately following EDFP (NIHSS score: 18 to 13). In conclusion, EDFP can increase CBF in ischemic brain tissue in acute atherothrombotic brain infarction. Further clinical studies should focus on the efficacy of EDFP on outcome of patients with this stroke subtype. J. Clin. Apheresis 18:167–174, 2003. © 2003 Wiley‐Liss, Inc.
Long‐term prognosis for Guillain‐Barré syndrome: Evaluation of prognostic factors and clinical experience of automated double filtration plasmapheresis
Authors: Cheng Ben‐Chung , Chang Wen‐Neng , Chen Jin‐Bor , Chee Esther Chung‐Yin , Huang Chi‐Ren , Lu Cheng‐Hsien , Chang Chin‐Jung , Hung Pi‐Lien , Chuang Yao‐Cheng , Lee Chien‐Te , Lee Ping‐Yu , Wang Kuo‐Wei , Chang Hsueh‐Wen
Published: December 2003

Sixty patients with Guillain‐Barré syndrome (GBS), aged 16–83 years, have been identified over a period of 7 years. Of 60 patients, 30 received the double filtration plasmapheresis (DFP), 4 received intravenous immunoglobulin, and the other 26 received supportive care only. Therapeutic outcomes at 1 year were determined using a modified Barthel index. At a follow‐up of 1 year or longer, 31 patients (52%) had recovered, 24 (40%) had residua, and 5 (8%) had died. According to the statistical analysis, disability at the nadir and electrophysiological signs significantly influenced the long‐term outcomes. Complications associated with DFP procedures included physiologic change, technique‐related complications, and vascular access‐related complications. None of our patients had fatal complications related to DFP treatment. Contrary to the established belief that the disease has a favorable outcome, several hospital‐treated patients may still die or present residua even several months after the onset of symptoms. Because disability at the nadir influences the outcomes, early diagnosis and choice of appropriate treatment, which might include DFP, to prevent further neurological deficits, are essential to maximize the potential for survival. J. Clin. Apheresis 18:175–180, 2003. © 2003 Wiley‐Liss, Inc.
Efficacy and safety of DALI LDL‐apheresis at high blood flow rates: A prospective multicenter study
Authors: Wendler T. , Schilling R. , Lennertz A. , Sodemann K. , Kleophas W. , Meßner H. , Riechers G. , Wagner J. , Keller C. , Bosch T.
Published: December 2003

Direct adsorption of lipids (DALI) is the first LDL‐apheresis method compatible with whole blood. Usually, the blood flow rate is adjusted at 60–80 ml/min, which results in session times of about 2 hr. The present study was performed to test the safety and efficacy of low‐density lipoprotein cholesterol (LDL‐C) and lipoprotein (a) [Lp(a)] removal by DALI at high blood flow rates in order to reduce treatment time. Thirteen chronic DALI patients in seven centers suffering from hypercholesterolemia (LDL‐C 162 ± 42 mg/dl at baseline) and coronary artery disease were treated on a weekly or biweekly basis by DALI apheresis. The blood flow rate QB was held constant for at least two sessions, respectively, and was increased from 60 to 80, 120, 160, 200, and 240 ml/min. All patients had pre‐existing av‐fistulas. The anticoagulation was performed by a heparin bolus plus ACD‐A at a ratio of citrate: blood ranging from 1:20 to 1:90. Clinically, the sessions were well tolerated and only 26/201 sessions (12%) of the treatments were fraught with minor adverse events. Acute LDL‐C reductions (derived from LDL‐C levels determined by lipoprotein electrophoresis) averaged 72/66/60/53/50/48% for QB = 60/80/120/160/200/240 ml/min. Lp(a) reductions were 68/67/62/60/58/56%, whereas HDL‐C losses were ≤10%. Routine blood chemistries and blood cell counts remained in the normal range. Treatment times averaged 142/83/45 min at Qb = 60/120/240 ml/min. On average, DALI LDL‐apheresis could be performed safely and effectively at high blood flow rates up to at least 120 ml/min in patients with good blood access, which significantly reduced treatment time from 142 to 83 min (−42%). J. Clin. Apheresis 18:157–166, 2003. © 2003 Wiley‐Liss, Inc.
Heat insoluble cryoglobulin associated with gangrene in multiple myeloma
Authors: Modarressi Amir , Kuriyan Mercy , Harvey Gail , Strair Roger
Published: December 2003

Cryoglobulins are immunoglobulins that have tendency to precipitate in temperatures below 37°C and dissolve with rewarming. Monoclonal cryoglobulins are usually associated with a distinct hematological disorder and often are asymptomatic. Heat insoluble cryoglobulin has been described with Sjogren's syndrome and glomerulonephritis but, not with multiple myeloma. Severe sensitivity to cold occurs with high thermal insolubility of the cryoprotein, with dramatic symptoms when exposed to minimal lowering of the temperature.

We report a case of a 49 year old man with multiple myeloma and an unusual type I cryoglobulin that caused occlusive gangrene. The cryoglobulin appeared as a milky white precipitate that was resistant to re‐suspension and did not dissolve at 37°C. Immunoelectrophoresis of the cryoglobulin, which dissolved at 56°C, showed it to be composed of a monoclonal IgG kappa protein (3.5 g/dl). Unlike most high thermal insoluble cryoglobulin, cold associated symptoms were not seen. In addition to steroids, plasmapheresis was initiated thrice a week with albumin fluid replacement.

Plasmapheresis caused a marked decline in cryocrit levels from 21% to less than 0.5% in 9 days after 4 procedures with resolution of the gangrene of the feet and after 6 treatments, vasculitic symptoms improved dramatically. The cryoglobulin test was negative 2 weeks after initiation of treatment. The patient was treated for the myeloma and there was no recurrence of occlusive symptoms.

Proper laboratory procedure and careful examination and handling of cryoglobulinemic samples facilitate detection of unusual cryoglobulins. This is a unique report of multiple myeloma with gangrene of lower extremities that has a heat insoluble cryoglobulin. J Clin Apheresis 18:190–193, 2003. © 2003 Wiley‐Liss, Inc.
Harvesting peripheral blood stem cells from healthy donors on 4th day of cytokine mobilization
Authors: Sohn Sang Kyun , Kim Jong Gwang , Sung Woo Jin , Kim Dong Hwan , Suh Jang Soo , Lee Kun Soo , Lee Kyu Bo
Published: December 2003

A pilot study was conducted to evaluate the efficacy of harvesting peripheral blood stem cells from normal healthy donors on day 4 after mobilization with G‐CSF at 10 μg/kg for 4 days or a sequential combination of GM‐CSF at 10 μg/kg for 2 days and G‐CSF at 10 μg/kg for 2 more days. Harvesting over the target dose (>4 × 106 kg) of CD34+ cells based on the lst leukapheresis performed on day 4 was possible from 7 (53.8%) out of 13 donors. The 7 matched recipients all exhibited early engraftment, except for one who experienced transplant‐related mortality, and no differences were observed with the recipients transplanted with stem cells harvested after a 5–6‐day growth‐factor (GF) treatment. Accordingly, harvesting from normal healthy donors on day 4 after mobilization treatment with a GF was found to be feasible for allogeneic peripheral blood stem cell transplantation and more economical in terms of the cost of the GF and the donor's commitment. J. Clin. Apheresis 18:186–189, 2003. © 2003 Wiley‐Liss, Inc.
Theoretical study on the rate constants for the C2H5 + HBr → C2H6 + Br reaction
Authors: Sheng Li , Li Ze‐Sheng , Liu Jing‐Yao , Xiao Jing‐Fa , Sun Chia‐Chung
Published: December 2003

The reaction C2H5 + HBr → C2H6 + Br has been theoretically studied over the temperature range from 200 to 1400 K. The electronic structure information is calculated at the BHLYP/6‐311+G(d,p) and QCISD/6‐31+G(d) levels. With the aid of intrinsic reaction coordinate theory, the minimum energy paths (MEPs) are obtained at the both levels, and the energies along the MEP are further refined by performing the single‐point calculations at the PMP4(SDTQ)/6‐311+G(3df,2p)//BHLYP and QCISD(T)/6‐311++G(2df,2pd)//QCISD levels. The calculated ICVT/SCT rate constants are in good agreement with available experimental values, and the calculate results further indicate that the C2H5 + HBr reaction has negative temperature dependence at T < 850 K, but clearly shows positive temperature dependence at T > 850 K. The current work predicts that the kinetic isotope effect for the title reaction is inverse in the temperature range from 200 to 482 K, i.e., kHBr/kDBr < 1. © 2003 Wiley Periodicals, Inc. J Comput Chem 25: 423–428, 2004
Theoretical model of internal rotation in monosubstituted derivatives of furfural
Authors: Crespo‐Otero Rachel , Montero Luis A. , Rosquete Giselle , Padrón‐García J. Alexander , González‐Jonte Raúl H.
Published: December 2003

The present work explores the effect of substitution in all free positions of furfural on conformational preferences of formyl group by using ab‐initio calculations at the MP2/6‐31G(p,d) level of theory. Theoretical modeling was made in vacuo. The selected substituents were CH3, NH2, NO2 and F groups in 3, 4, 5 and ipso carbonyl positions. Geometries of all derivatives were analyzed and it is ascertained that substitution has not important consequences on furan ring geometry. Differences of energy between OO‐cis and trans conformers and energy barriers between them are described and extreme cases are explained. Interesting features appear in the cases of NH2 and NO2 groups, and particularly when the 3 and ipso carbonyl positions are substituted. Variations in energy barriers are correlated with variations in C2‐C6 distances for the transition states and planar forms. Substitution effect on Mülliken charges are analyzed and related with internal rotation energy barriers and differences between conformers. © 2003 Wiley Periodicals, Inc. J Comput Chem 25: 429–438, 2004
Analysis of the intermolecular interactions between CH3OCH3, CF3OCH3, CF3OCF3, and CH2F2, CHF3
Authors: Urata Shingo , Tsuzuki Seiji , Takada Akira , Mikami Masuhiro , Uchimaru Tadafumi , Sekiya Akira
Published: December 2003

The intermolecular interaction energy curves of CH3OCH3CH2F2, CF3OCH3CH2F2, CF3OCF3CH2F2, CH3OCH3CHF3, CF3OCH3CHF3, and CF3OCF3CHF3complexes were calculated by the MP2 levelab initiomolecular orbital method using the 6‐311G** basis set augmented with diffuse polarization functions. We investigate the fluorine substitution effects of both methane and dimethyl ether on intermolecular interactions. In addition, orientation dependence of intermolecular interaction energies is also studied with utilizing eight types of orientations. Our analyses demonstrate that partial fluorinations of methane make electrostatic interaction dominant, and consequently enhance attractive interaction at several specific orientations. On the contrary, fluorine substitutions of dimethyl ether substantially decrease the electrostatic interaction between ether and CH2F2or CHF3; thus, there is no such characteristic interaction between the CH of fluorinated methane and ether oxygen of CF3OCF3as conventional hydrogen bonding, due to reduced polarity of fluorinated ether. The combination of different pairs of the electrostatic interaction is therefore responsible for the intermolecular interaction differences among the complexes investigated herein and also their orientations. © 2003 Wiley Periodicals, Inc. J Comput Chem 25: 447–459, 2004
Separation of some metal ions by high performance centrifugal partition chromatography with di‐2‐methylnonylphosphoric acid
Authors: Nagaosa Yukio , Wang Tao
Published: December 2003

The separation of such metal ions as Cu(II), Mn(II), Co(II), Ni(II), Mg(II) and Ca(II) has been investigated by high performance centrifugal partition chromatography (HPCPC) employing di‐2‐methylnonylphosphoric acid/heptane as a stationary phase. The four transition metal ions have mutually been separated by the two‐step elution method, changing the pH of the chloroacetic acid mobile phase, and the two alkaline earth metal ions have been separated by an isocratic elution. The HPCPC system was operated with 2136 partition channels, at a rotation speed of 800 rpm, and at a flow rate of 2.0 cm3 min−1. The elution curve was obtained by monitoring the absorbance of each metal complex post‐labeled with chromogenic compounds. Copyright © 2003 Society of Chemical Industry
Protease and xylanase activities and thermophilic populations as potential process monitoring tools during thermophilic aerobic digestion
Authors: Ugwuanyi J Obeta , Harvey Linda M , McNeil Brian
Published: December 2003

Thermophilic aerobic digestion (TAD) of potato process waste slurry was carried out in a batch process in a continuously stirred tank reactor at 55 °C for a total of 156 h. The pH of the slurry was either unregulated, or regulated at 6.0, 7.0, 8.0, 9.0 and 9.5, and aeration rate was 0.5 vvm. The effect of aeration rate on the digestion process was studied at 0.1, 0.25, 0.5 and 1.0 vvm at pH 7.0 and 55 °C. The development of thermophiles (55 and 65 °C populations) and hydrolytic enzyme activities (protease and xylanase) in the process were monitored. Thermophiles developed rapidly to reach peak populations in 24h or earlier, and remained stable at all fixed pH reactions. The thermophile population was only minimally affected by the aeration rate, and they were present mostly as spores after 96h of digestion. Xylanase enzyme appeared rapidly, reached a peak in approximately 60h, and declined rapidly thereafter. Highest activities were produced in neutral reactions and higher aeration rates. Aeration rates affected protease activity profoundly. The profile of both enzymes closely reflected the development of microbial activity and the overall progress of TAD, in a medium where their substrates were not predominant and not the preferred carbon sources. The relatively simple process of measuring the activities of these enzymes is potentially a more direct measure of the progress of TAD than enumeration of the microbial populations and thus, has greater potential in process monitoring. Copyright © 2003 Society of Chemical Industry
Separation of strontium and cadmium ions from nitrate medium by ion‐exchange membrane in an electrodialysis system
Authors: Gasser MS , Nowier HG
Published: December 2003

The separation of strontium and cadmium ions in a system containing ethylenediaminetetraacetic acid (EDTA) as a complexing agent has been studied using a three‐compartment electrolytic cell. The results suggest that under the influence of an electric field, Sr ions were exclusively transported to the cathode as positively charged uncomplexed cations while cadmium ions removed from the middle compartment of the electrolytic cell migrated to the anode as negatively charged complexes. The effect of the EDTA complexing agent on the separation was studied within the pH range 2–4 at 100 mA (12.4 mA cm−2). Copyright © 2003 Society of Chemical Industry
Kinetics of the oxidative degradation of thionine dye by hydrogen peroxide catalyzed by supported transition metal ions complexes
Authors: Gemeay Ali H , Mansour Ikhlas A , El‐Sharkawy Rehab G , Zaki Ahmed B
Published: December 2003

The kinetics of the catalyzed oxidative mineralization of the thionine dye (TH) (3,7‐diamino‐phenothiazin‐5‐ylium acetate) with H2O2 has been studied. The catalysts used were supported silica, alumina, and cation‐exchange resins (Dowex‐50W, 2 and 8% DVB) in the form of transition metal complexes. These complexes were [Cu(amm)4]2+, [Co(amm)6]2+, [Ni(amm)6]2+, [Cu(en)2]2+, and [Cu(ma)4]2+ (amm = ammonia, en = ethylenediamine, and ma = methylamine). The reaction exhibited first‐order kinetics with respect to thionine dye concentration, [TH], while the order with respect to [H2O2] was dependent on the catalyst type and the concentration range. The reactivity of the catalysts is correlated with the redox potential of metal ions, the amount of complex per gram of air‐dried support, and the type of support. The rate of the reaction increased with increasing pH of the medium. Addition of β‐cyclodextrin exhibited three distinct effects depending on the concentration range. The inclusion of the substrate and the oxidizing species has been evaluated. The irradiation of the reaction with UV‐light enhanced the rate of TH mineralization by about 20%. The reaction was enthalpy‐controlled as confirmed from the isokinetic relationship. A reaction mechanism was proposed with the formation of free radicals as reactive intermediates. Copyright © 2003 Society of Chemical Industry
Microbial composition and structure of a multispecies biofilm from a trickle‐bed reactor used for the removal of volatile aromatic hydrocarbons from a waste gas
Authors: Hekmat Dariusch , Feuchtinger Annette , Stephan Markus , Vortmeyer Dieter
Published: December 2003

The microbial composition and structure of a multispecies biofilm of a laboratory‐scale trickle‐bed bioreactor for the treatment of waste gas was examined. The model pollutant was a volatile organic compound‐mixture of polyalkylated benzenes called Solvesso 100®. Fluorescent in‐situ hybridization (FISH) and confocal laser scanning microscopy (CLSM) were applied. Two new Solvesso 100®‐degrading Pseudomonas sp strains were isolated from the multispecies biofilm. Corresponding isolate‐specific oligonucleotide probes were designed and applied successfully. A major finding was that the fraction of Solvesso 100®‐degrading bacteria in the biofilm was low (about 3–6% during long‐term operation). The majority of the active cells were saprophytes which utilized intermediates and cell lysis products. The measured fraction of extracellular polymeric substances of the mature biofilm was 89–93% of the total biomass. The CLSM examinations of a 3‐days‐old approx 10 µm thick biofilm revealed highly heterogeneous structures with distinguished three‐dimensional matrix‐enclosed microcolony bodies spread across the substratum surface. The 28‐days‐old 80–960 µm thick biofilm exhibited voids, cell‐free channels, and pores of variable sizes. In both cases, an even distribution of active cells and pollutant‐degrading bacteria throughout the biofilm cross‐section as well as through the biofilm depth was observed. Copyright © 2003 Society of Chemical Industry
Biodepyritisation of coal
Authors: Acharya C , Sukla LB , Misra VN
Published: December 2003

This review provides a detailed summary of the recent and past research activities in the area of biodesulfurisation of coal. It provides information about microorganisms important for biodesulfurisation of coal, with the emphasis on Thiobacillus ferrooxidans. The review presents an insight into various methods of desulfurisation of coal combining physical and biological methods. Also, there are discussions on coal structure, distribution, mechanism and kinetics of pyrite oxidation and jarosite precipitation. Finally, areas requiring further research are identified. Copyright © 2003 Society of Chemical Industry
Two‐phase anaerobic treatment system for fat‐containing wastewater
Authors: Kim Sang‐Hyoun , Han Sun‐Kee , Shin Hang‐Sik
Published: December 2003

This study was conducted to investigate the feasibility of a two‐phase anaerobic treatment system for fat‐containing wastewater. The two‐phase system was composed of a continuously stirred tank reactor for acidogenesis and an upflow anaerobic sludge blanket (UASB) reactor for methanogenesis. Its performance was compared with a conventional single‐phase system of a UASB reactor treating synthetic wastewater containing major long‐chain fatty acids (LCFAs). LCFAs did not cause any significant problem up to the LCFA mixture loading rate of 1.21 kg LCFA‐COD m−3 day−1 (3500 mg LCFA‐COD dm−3) in both systems. However, the efficiency of the single‐phase system deteriorated at loading rates above 1.38 kg LCFA‐COD m−3 day−1 (4000 mg LCFA‐COD dm−3), while that of the two‐phase system was still satisfactory. More than 19.2% of LCFAs were degraded and 11.5% of unsaturated LCFAs were saturated in the acidogenesis of the two‐phase system, which led to the enhanced specific methane production rate and the reduced scum layer of the subsequent UASB reactor. Copyright © 2003 Society of Chemical Industry
Regression and the hypothesis of accelerated life
Authors: Hutchinson TP
Published: December 2003

Experiments on accelerated aging assume that curves of performance (vertical axis) versus logarithm of time (horizontal axis) are parallel in different conditions (eg temperatures), in the sense of being a constant horizontal distance apart. It is shown how multiple regression may be adapted to the estimation of the horizontal shifts, which can then be related to objective measures of the conditions. Copyright © 2003 Society of Chemical Industry
Ferumoxide‐enhanced MR imaging of hepatocellular carcinoma: Correlation with histologic tumor grade and tumor vascularity
Authors: Kato Hiroki , Kanematsu Masayuki , Kondo Hiroshi , Goshima Satoshi , Matsuo Masayuki , Hoshi Hiroaki , Moriyama Noriyuki
Published: December 2003

Purpose

To evaluate ferumoxide‐enhanced MR imaging findings of hepatocellular carcinomas (HCCs) in correlation with the histologic tumor grades and the tumor vascularity evaluated by CT hepatic arteriography (CTHA) and CT during arterial portography (CTAP) combined.

Materials and Methods

By searching the radiologic, surgical, and pathologic reports of our institution between January 1999 and February 2001, we identified 43 patients with 51 pathologically confirmed HCCs who underwent ferumoxide‐enhanced MR imaging and combination CTHA and CTAP within two weeks. The HCCs consisted of 17 well‐differentiated, 28 moderately differentiated, and six poorly differentiated tumors. The MR and CT were retrospectively reviewed by two radiologists in consensus for signal intensity on MR images and vascularity on CT. The Spearman's rank correlation coefficient was calculated to correlate the frequency of tumors with ferumoxide uptake with the histologic tumor grades and the tumor vascularity on CTHA and CTAP.

Results

A total of 45 tumors (88%) did not take up ferumoxide, and thus showed distinct, homogeneous hyperintensity. Six tumors (12%) ranging 5–16 mm in size (mean, 11 mm) took up ferumoxide, and thus showed isointensity, mixed intensity, or hypointensity, including five of 17 (29%) well‐differentiated tumors and one of 28 (4%) moderately differentiated tumors. Five of the six tumors (83%) showed hyper‐ or hypovascularity on CTHA or hypovascularity on CTAP. The frequency of tumors with ferumoxide uptake showed weak correlation with tumor grades (coefficient = 0.26, P < 0.01) and vascularity on CTHA (–0.35, P < 0.05) and CTAP (0.39, P < 0.01).

Conclusion

Although a small number of well‐differentiated HCC take up ferumoxide and show iso‐, mixed, or hypointensity, most such tumors show increased hepatic arterial or decreased portal venous perfusion. The present results suggest the limitation of reticuloendothelial contrast imaging, particularly in the diagnosis of small, well‐differentiated HCC. J. Magn. Reson. Imaging 2004;19:76–81. © 2003 Wiley‐Liss, Inc.