bluuebunny/crossref_metadata_2025 huggingface dataset:
Quality of life in old age: An investigation of well older persons in Hong Kong
Authors: Cheng Sheung‐Tak , Chan Alfred C.M. , Phillips David R.
Published: April 2004

What might add quality to life during the last period of the life cycle? In study I, five focus groups of elderly participants representing different ages and socioeconomic backgrounds provided descriptions of quality of life (QOL) from their own perspectives. These descriptions formed the basis of a questionnaire that was administered to a representative, random sample of older persons in Hong Kong (N = 1,616) in study II. The study II sample was further randomly split into two. Exploratory factor analysis on sample A identified four factors: generativity, interpersonal (including intergenerational) relations, physical functioning, and material life. Results of confirmatory factor analysis on sample B showed that the 4‐factor QOL model provided a good fit to the data, and that the constructs measured were identical (invariant) between older men and women and between the young‐old and the old‐old. In study III, the findings were disseminated back to an independent sample of older persons meeting in focus groups, who provided verbal confirmations to the model. The findings shed light on possible community psychology interventions to promote wellness in the elderly. © 2004 Wiley Periodicals, Inc. J Comm Psychol 32: 309–326, 2004.
Olfactory receptors in the mouse septal organ
Authors: Kaluza Jan F. , Gussing Fredrik , Bohm Staffan , Breer Heinz , Strotmann Jörg
Published: April 2004

In this study we have identified a repertoire of chemosensory receptors expressed in the septal organ (SO). The results suggest that septal organ neurons are specified to express receptor genes belonging to class II olfactory receptors that are also expressed in the main olfactory epithelium. We found no evidence for the expression of members from the vomeronasal receptor gene families. In the SO, no topography analogous to the receptor expression zones of the main olfactory epithelium was evident. The majority of identified receptors corresponds to genes with restricted expression in the medial and lateral zones of the main olfactory epithelium. This coincides with the expression of olfactory cell adhesion molecule (OCAM) throughout the SO, which is considered as a marker for the medial‐lateral zones. In contrast, NADPH:quinone oxidoreductase 1 expression, a characteristic marker for the dorsal zone, was lacking in the SO. Most of the receptor types were found to be expressed in rather few SO neurons; as an exception, the receptor mOR244‐3 was observed in a very high proportion of cells. Although a very high fraction of SO neurons expressed mOR244‐3, we found no evidence for the coexpression of different receptors in individual cells. © 2004 Wiley‐Liss, Inc.
Administration of N‐acetylcysteine after focal cerebral ischemia protects brain and reduces inflammation in a rat model of experimental stroke
Authors: Khan Mushfiquddin , Sekhon Bipanjeet , Jatana Manu , Giri Shailendra , Gilg Anne G. , Sekhon Charanpal , Singh Inderjit , Singh Avtar K.
Published: April 2004

Free radicals and inflammatory mediators are involved in transient focal cerebral ischemia (FCI). Preadministration of N‐acetylcysteine (NAC) has been found to attenuate the cerebral ischemia‐reperfusion injury in a rat model of experimental stroke. This study was undertaken to investigate the neuroprotective potential of NAC administered after ischemic events in experimental stroke. FCI was induced for 30 min by occluding the middle cerebral artery (MCA). NAC (150 mg/kg) was administered intraperitoneally at the time of reperfusion followed by another dose 6 hr later. Animals were sacrificed after 24 hr of reperfusion. The cerebral infarct consistently involved the cortex and striatum. Infarction was assessed by staining the brain sections with 2,3,5‐triphenyltetrazolium chloride. Animals treated with NAC showed a significant reduction in infarct area and infarct volume and an improvement in neurologic scores and glutathione level. Reduction in infarction was significant even when a single dose of NAC was administered at 6 hr of reperfusion. Immunohistochemical and quantitative real‐time PCR studies demonstrated a reduction in the expression of proinflammatory cytokines such as tumor necrosis factor α (TNFα) and interleukin 1β (IL‐1β) and inducible nitric oxide synthase (iNOS) in NAC compared to that in vehicle‐treated animals. The expression of activated macrophage/microglia (ED1) and apoptotic cell death in ischemic brain was also reduced by NAC treatment. These results indicate that in a rat model of experimental stroke, administration of NAC even after ischemia onset protected the brain from free radical injury, apoptosis, and inflammation, with a wide treatment window. © 2004 Wiley‐Liss, Inc.
Effect of temperature and pH on the toxicity of aluminium towards two new, soil born species of Arthrobacter sp.
Authors: Illmer Paul , Mutschlechner Wolfgang
Published: April 2004

Two coryneform bacteria Arthrobacter sp. PI/1–95 (Arth1) and Arthrobacter sp. PI/3‐95 (Arth3) were isolated from forest soil characterized and investigated with respect to their reaction towards aluminium (Al). Sigmoid functions were used to describe dose‐response relationships between Al concentration and microbial growth and to calculate EC‐values. EC100 – indicating a complete inhibition of microbial growth – varied between 185 μM Al for Arth1 and 11 mM Al for Arth3. A pure pH effect seems probable in connection with the sensitive Arth1 but not with the tolerant species Arth3. Temperature was shown to distinctly increase the toxic effects of Al towards Arth3 whereas only a moderate modification in Al‐toxicity was observed with Arth1. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Adaptive acid tolerance response in Salmonella enterica serovar Typhimurium and Salmonella enterica serovar Typhi
Authors: Parkash Tiwari Ram , Sachdeva Naresh , Singh Hoondal Gurinder , Singh Grewal Jasvir
Published: April 2004

The survival of bacteria in various environments depends on a number of protective responses including acid tolerance response (ATR). In this study, ATR phenomenon was compared in Salmonella enterica serovar Typhi 6 and Salmonella enterica serovar Typhimurium 98 under different culture conditions. Survival of the adapted culture (pre‐acid shocked to pH 5.5) was significantly better (p < 0.05) as compared to control, unadapted culture after acid shock at pH 3.3. However, the ATR varied with the serovar, incubation temperature and the growth medium used (all p‐values < 0.05). S. Typhi 6 failed to grow in pH 3.3 at 45 °C. The addition of tetracycline or chloramphenicol (1.0 μg ml−1) to adapted cultures during or after acid shock (pH 3.3) had no effect on ATR expression. In S. Typhimurium 98, growth was increased by 10% or greater in adapted culture (when grown at pH 3.3) as compared to growth observed with an unadapted culture (when grown at pH 7.3) on transfer to fresh growth medium at pH 7.3. A poor ATR observed in non‐growing S. Typhimurium 98 suspensions clearly showed that ATR is an energy‐consuming process. Storage of S. Typhimurium 98 cultures in pH 4.5 nutrient broth at 4 °C demonstrated that prolonged exposure to acidic conditions is more detrimental in comparison to the cultures stored at pH 7.3 at this temperature. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Isolation and characterization of cerebrosides of the hydrocarbon‐assimilating yeast Yarrowia lipolytica
Authors: Rupčić Jasminka , Georgiù Kata , Marić Vladimir
Published: April 2004

Yarrowia lipolytica yeast was grown batchwise on n‐hexadecane as the carbon and energy source. Two cerebroside species were quantitatively isolated from sphingolipid fractions of total lipids by a combination of column chromatography and preparative high‐performance thin‐layer chromatography. The cerebroside content accounted for 1.3% of the total cell lipids. Glucose was detected as the sole sugar constituent in cerebrosides. The fatty acid composition of cerebrosides was characterized by a high proportion of hydroxylated long‐chain saturated fatty acids. The major fatty acids were h16:0 and 16:0. The long‐chain bases composition shows a preponderance of trihydroxy bases and a small amount of dihydroxy bases. The striking finding was a high proportion of 19‐phytosphingosine. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microbial detoxification of mycotoxin deoxynivalenol
Authors: Völkl Andrea , Vogler Bernhard , Schollenberger Margit , Karlovsky Petr
Published: April 2004

Deoxynivalenol (DON) is a trichothecene secondary metabolite produced by Fusarium species infecting cereal crops. As a mycotoxin, DON causes losses in livestock production and poses a health risk to humans consuming contaminated cereal products. DON also acts as a virulence factor, facilitating the colonization of host plants by Fusarium spp. Enzymatic detoxification of mycotoxins in feed additives and genetically modified crops is a promising approach for the reduction of mycotoxin contamination of feeds and food. A prerequisite for the developoment of biotechnological strategies for DON detoxification is the availability of genes encoding suitable enzymatic activities. With the goal of isolating microbial cultures that can be used as a source of such activies, we screened 1285 microbial cultures from farmland soil, cereal grains, insects and other sources for DON transformation under aerobic conditions. One mixed culture transformed DON into two chromatographically separable products. The main product of the transformation was purified and its structure was elucidated by mass spectroscopy, 1H‐NMR, 13C‐NMR and proton‐proton and carbon‐proton correlated NMR spectroscopy. The structure of this product was determined to be 3‐keto‐4‐deoxynivalenol. The DON‐transforming mixed culture survived and retained its transforming activity during a starvation period of six months at 20 °C. Transformation of DON was suppressed by low concentrations of glucose and high concentrations of tryptone and yeast extract. Cell‐free supernatants obtained either by filtration through a 0.22 μm membrane filter or by centrifugation did not exert DON‐transforming activity. Trichothecenes 15‐acetyl‐DON, 3‐acetyl‐DON and fusarenon‐X were also transformed. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Production of laccase isoforms by Pleurotus pulmonarius in response to presence of phenolic and aromatic compounds
Authors: Giatti Marques De Souza Cristina , Kirst Tychanowicz Giovana , Farani De Souza Daniela , Peralta Rosane Marina
Published: April 2004

The effect of several phenolic and aromatic monomers structurally‐related to lignin on production of laccase by the white rot fungus P. pulmonarius (Fr.) Quélet has been studied. In the absence of an inducer, laccase was maximally produced after depletion of carbon and nitrogen sources. Among 15 phenolic and aromatic compounds tested, ferulic acid and vanillin were the most efficient inducers, increasing the production of laccase activity up to 10 times. A mixture of ferulic acid and vanillin was more efficient to induce the production of laccase than the isolated phenolics. At least three laccase isoforms designated as lcc1, lcc2 and lcc3 were identified by eletrophoretic analysis of P. pulmonarius culture filtrates. The lcc1 and lcc2 isoforms were produced by non‐induced cultures, while lcc3 was found only in induced‐culture filtrates. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the evaluation of the nonisothermal kinetic parameters of (GeS2)0.3(Sb2S3)0.7 crystallization using the IKP method
Authors: Budrugeac P. , Criado J. M. , Gotor F. J. , Malek J. , Pérez‐Maqueda L. A. , Segal E.
Published: April 2004

The isoconversional method suggested by Friedman and the invariant kinetic parameters method (IKP) were used in order to examine the kinetics of the nonisothermal crystallization of (GeS2)0.3(Sb2S3)0.7. The objective of the paper is to show the usefulness of the IKP method both for determining the activation parameters as well as the model of the investigated process. It was shown that the kinetic triplet [(E, A, f(α), where E is the activation energy, A is the preexponential factor, and f(α) is the differential function of conversion], which results through the application of the IKP method, depends on the set of kinetic models considered. For different sets of kinetic models, proportional values of f(α) are obtained. A criterion for the selection of this set, the use of which lead to the true kinetic triplet corresponding to the analyzed process (E = 163.2 kJ mol−1; A = 2.47 × 1012 min−1 and the Avrami‐Erofeev model, Am, for m = 2.5–2.6 was suggested. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 309–315, 2004
Effects of mixed aqueous‐organic solvents on the rate of intramolecular carboxylic group‐catalyzed cleavage of N‐(4′‐methoxyphenyl)phthalamic acid
Authors: Leng Sim Yoke , Ariffin Azhar , Khan M. Niyaz
Published: April 2004

Kinetic study on the cleavage of N‐(4′‐methoxyphenyl)phthalamic acid (NMPPAH) in mixed H2O‐CH3CN and H2O‐1,4‐dioxan solvents containing 0.05 M HCl reveals the formation of phthalic anhydride (PAn)/phthalic acid (PA) as the sole or major product. Pseudo first‐order rate constants (k1) for the conversion of NMPPAH to PAn decrease nonlinearly from 60.4 × 10−5 to 2.64 × 10−5 s−1 with the increase in the contents of 1,4‐dioxan from 10 to 80% v/v in mixed aqueous solvents. The rate of cleavage of NMPPAH in mixed H2O‐CH3CN solvents at ≥50% v/v CH3CN follows an irreversible consecutive reaction path: NMPPAH PA. The values of k1 are larger in H2O‐CH3CN than in H2O‐1,4‐dioxan solvents. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 316–325, 2004
Poröse Scaffolds aus mineralisiertem Kollagen – ein biomimetisches Knochenersatzmaterial
Authors: Gelinsky M. , König U. , Sewing A. , Pompe W.
Published: April 2004

Aus biomimetisch mit Hydroxylapatit mineralisierten Kollagen Typ I Fibrillen wurde ein neuartiges poröses Knochenersatzmaterial entwickelt, das in seiner chemischen Zusammensetzung der extrazellulären Matrix von Knochengewebe nahekommt. Die Porenstruktur wird über einen Gefriertrocknungsprozeß erzeugt, wobei über die Geschwindigkeit und die Temperatur des Einfriervorgangs die Porengröße über einen weiten Bereich eingestellt werden kann. Durch chemische Quervernetzung des Kollagen‐Anteils mit dem wasserlöslichen Carbodiimid‐Derivat EDC wird die Struktur stabilisiert. Als optimal für die Besiedlung mit Knochenzellen haben sich interkonnektierende Poren mit Durchmessern von ca. 200 μm erwiesen; die entsprechenden Scaffolds sind im feuchten Zustand elastisch, was die Durchführung von Zellkulturexperimenten unter mechanischer Stimulation ermöglicht.
Cerabone® – eine Spongiosa‐Keramik bovinen Ursprungs
Authors: Seidel P. , Dingeldein E.
Published: April 2004

Bei dem Implantatmaterial Cerabone® handelt es sich um eine Hydroxylapatitkeramik mit dem Hauptbestandteil Pentacalcium‐hydroxid‐[tris]phospat. Die Gewinnung des Implantates erfolgt durch die Präparation tierischer Knochen, die durch Temperaturprozesse in ihre keramische Form transformiert werden. Aufgrund des spongiösen Ausgangsmateriales besitzt Cerabone® ein interkonnektierendes makro‐ und mikroporöses Porensystem. Dieses liefert dem neuzubildenden Knochen eine strukturierte Leitschiene, in und um die ausgehend vom Lagerknochen neuer Knochen angelagert wird. Der durch die Herstellungsprozesse beibehaltene Aufbau der natürlichen Spongiosa wirkt sich besonders gut auf die mechanischen Eigenschaften des Implantates und das Einwachsverhalten des neuen Knochens nach der Implantation aus.
New Aspects in Osteoinduction
Authors: Stoll T. , Maissen O. , Meury T. , Becker S.
Published: April 2004

Bone grafting is a widely used procedure to treat bone defects. Various synthetic bone substitutes are gaining upon autologous cancellous bone, which is still the most effective graft material, despite the associated morbidity at the harvesting site. The lack of osteoinductive or osteogenic properties limits the success of those materials compared to autograft. One approach to enhance their biological behaviour is the addition of blood or bone marrow derived cellular material. Both platelet rich plasma (PRP) and fresh bone marrow (BM) have been reported to enhance bone formation clinically. The aim of this work was to evaluate in a pilot study the osteogenic potential of autologous substances like blood and bone marrow processed intra‐operatively in order to be impregnated on a synthetic ceramic bone substitute.
Porous nitinol vs. titanium intervertebral fusion implants: Computer tomography, radiological and histological study of osseointegration capacity
Authors: Assad M. , Likibi F. , Jarzem P. , Leroux M. A. , Coillard C. , Rivard Ch.‐H.
Published: April 2004

The functionality of a new metallic interbody fusion implant manufactured out of porous nitinol (PNT) was evaluated in sheep and compared to a conventional titanium intervertebral cage packed with autologous iliac crest bone. Both device types were implanted at two non‐contiguous intervertebral lumbar sites. The objective was to evaluate the osseointegration capacity after 3, 6 and 12 months of implantation in the presence of these two implant types subjected to the same mechanical loads. Two‐dimensional radiolology, computer tomography, and histology were used as techniques of parameters evaluation. The results indicated that PNT obtained a better intervertebral osseointegration capacity compared to the TiAlV cage. The functional difficulties of the titanium implant were related to its instability at the implantation site possibly due to a biofunctionality problem. The biocompatibility of both implants seemed however comparable.
Klinische Anwendungsmöglichkeiten von porösen Biomaterialien im Knochengewebe
Authors: Esenwein S. A. , Esenwein S. , Hartwig C.‐H. , Herr G. , Muhr G.
Published: April 2004

Im Bereich der Versorgung von Knochendefekten besteht oft die Notwendigkeit, größere Defekte aufzufüllen. Dabei werden poröse Biomaterialien als Alternative zu autologem Spenderknochen häufig in der Implantologie, Traumatologie und orthopädischen Chirurgie mit guten klinischen Ergebnissen eingesetzt. Im Gegensatz zur autologen Spongiosa sind sie nahezu unbegrenzt verfügbar und nicht mit dem Problem der Spendermorbidität behaftet. Um die Menge und Qualität des neugebildeten Knochens und damit die Auffüllung eines Defektes zu beschleunigen, werden unterschiedliche Biomaterialien als Knochenersatzmaterialien eingesetzt. Es handelt sich dabei um Werkstoffe, die in der Lage sind, mit biologischen Systemen zu interagieren, wobei vor allem synthetische poröse Tricalciumphosphat‐ und Hydroxylapatitkeramiken sowie prozessierte Allografts zum Einsatz kommen. Als weitere klinische Anwendungsmöglichkeit kommt die Oberflächenbeschichtung von Implantaten mit porösen Biomaterialien und knochenbildenden Wachstumsfaktoren zur Verbesserung der knöchernen Integration in betracht.

In der vorliegenden Arbeit soll ein Überblick über die klinischen Anwendungsmöglichkeiten von porösen Biomaterialien im Knochengewebe sowie ein Ausblick auf zukünftige Entwicklungen gegeben werden.
Oberflächenmodifizierung von Titan zur Verbesserung der Grenzflächenverträglichkeit
Authors: Klee D. , Böing J. , Höcker H.
Published: April 2004

Im Rahmen der vorliegenden Arbeit wurde die CVD‐Polymerisation von aminosubstituiertem [2,2]‐Paracyclophan zur Polymerbeschichtung und gleichzeitigen Funktionalisierung von Titan‐Oberflächen durchgeführt. Parallel erfolgte die Funktionalisierung mittels Silanisierung mit 3‐Aminopropyl‐triethoxysilan. Die generierten Aminogruppen wurden zur kovalenten Immobilisierung von bioaktiven Substanzen genutzt, um die Adhäsion von Knochenzellen zu fördern und deren Wachstum zu stimulieren. Als bioaktive Substanzen wurden das Pentapepid GRGDS und der Wachstumsfaktor BMP‐2 ausgewählt. Die kovalente Bindung wurde mit dem Kopplungsreagenz Hexamethylendiisocyanat durchgeführt. Zur Charakterisierung der einzelnen Modifizierungsschritte wurden die Röntgenphotoelektronenspektroskopie, die Rasterkraftmikroskopie und die Kontaktwinkelmessung eingesetzt. Der Nachweis der kovalenten Bindung der bioaktiven Substanzen erfolgte mittels radioaktiver Markierung bzw. Surface‐MALDI‐ToF‐MS. In vitro‐Biokompatibilitätstests mit primären, humanen Osteoblasten zeigten die Verbesserung der Zelladhäsion und des Spreadings auf den bioaktiv ausgerüsteten Titanoberflächen.
Steroid sulfatase inhibitors
Authors: Nussbaumer Peter , Billich Andreas
Published: April 2004

Steroid sulfatase (STS) regulates the local production of estrogens and androgens from systemic precursors in several tissues. The enzyme catalyzes the hydrolysis of the sulfate esters of 3‐hydroxy steroids, which are inactive transport or precursor forms of the active 3‐hydroxy steroids. STS inhibitors are expected to block the local production and, consequently, to reduce the local levels of the hormones. Therefore, they are considered as potential new therapeutic agents for the treatment of estrogen‐ and androgen‐dependent disorders. Indications range from cancers of the breast, endometrium and prostate to androgenetic alopecia and acne. In this review, we give a comprehensive summary of the current knowledge and problems in the field of medicinal chemistry of STS inhibitors. The various types of inhibitors are presented and their structure‐activity relationships are discussed. In addition to potent arylsulfamate‐based, irreversible inhibitors, novel types of reversible inhibitors were recently discovered. The recent publication of the X‐ray structure of STS will further boost research activities on this attractive target. © 2004 Wiley Periodicals, Inc. Med Res Rev, 24, No. 4, 529–576, 2004
Physician adherence to recommendations for duration of empiric antibiotic treatment for uncomplicated urinary tract infection in women: a national drug utilization analysis
Authors: Kahan Natan R. , Chinitz David P. , Kahan Ernesto
Published: April 2004

Background

Current guidelines for the empiric treatment of uncomplicated urinary tract infection in women recommend that first‐line trimethoprim‐sulfamethoxazole (TMP‐SMX) or ofloxacin be given for 3 days and nitrofurantoin for 5 days. Increasing the duration of treatment raises costs, and perhaps, the incidence of adverse effects, without contributing to effectiveness. The aim of this study was to investigate physician adherence to these recommendations.

Methods

The electronic patients record system of a nationwide health management organization in Israel was reviewed for all primary care visits by adult women treated empirically for cystitis or urinary tract infection from January 2001 to June 2002 (n = 7738 patient–physician encounters). The proportion of cases treated according to the guidelines, with regard to duration, was calculated for each drug used.

Results

Rate of adherence was 3.36% for cases of TMP‐SMX treatment (95%CI: 2.56%, 4.15%), 22.23% for nitrofurantoin (95%CI: 19.81%, 24.65%) and 4.08% for ofloxacin (95%CI: 2.88%, 5.28%). The crude rate of adherence for all cases of treatment with these drugs was 8.67% (95%CI: 7.82%, 9.52%).

Conclusions

The high rate of nonadherence observed (91.33%) indicate a need for a remedial education program for physicians to improve empiric treatment of urinary tract infection in women. Since this issue is of global importance, we believe our evaluation can serve as model for other settings and countries. Copyright © 2003 John Wiley & Sons, Ltd.
Potential savings from increased use of generic drugs in the elderly: what the experience of Medicaid and other insurance programs means for a Medicare drug benefit
Authors: Fischer Michael A. , Avorn Jerry
Published: April 2004

Background

Generic medications provide the same clinical effect at lower cost than brand name drugs but little is known about the extent to which such savings are achieved in drug benefit programs serving the elderly.

Methods

Using patient‐level claims data for participants aged 65 or more in one state Medicaid program and in a non‐Medicaid drug insurance program for the elderly, we compared the expenditures in each program for brand name prescriptions with the amount that would have been paid for generic versions of the same agents. We then estimated potential savings from increased use of substitutable brand name drugs.

Results

There was an unrealized annual savings of $3.4 million (3.6% of total drug expenditure) in the Medicaid program studied and $13.7 million (9.5% of total drug expenditure) in the non‐Medicaid drug insurance program for the elderly, with corresponding reductions in mean annual per‐patient drug costs.

Conclusions

More widespread use of generic medications represents an important source of unrealized savings in drug coverage programs for the elderly. The Medicaid program limits the excess spending on brand name drugs by imposing pricing restrictions, but many non‐Medicaid programs could realize even larger savings from reducing the use of brand name drugs when identical generic products are available. These findings offer some insight into the potential expense of a Medicare prescription drug benefit. Copyright © 2003 John Wiley & Sons, Ltd.
Novel, biodegradable, functional poly(ester‐carbonate)s by copolymerization of trans‐4‐hydroxy‐L‐proline with cyclic carbonate bearing a pendent carboxylic group
Authors: Lee Ren‐Shen , Yang Jen‐Ming , Lin Tz‐Feng
Published: April 2004

Water‐soluble poly(ester‐carbonate) having pendent amino and carboxylic groups on the main‐chain carbon is reported for the first time. This article describes the melt ring‐opening/condensation reaction of trans‐4‐hydroxy‐N‐benzyloxycarbonyl‐L‐proline (N‐CBz‐Hpr) with 5‐methyl‐5‐benzyloxycarbonyl‐1,3‐dioxan‐2‐one (MBC) at a wide range of molar fractions. The influence of reaction conditions such as catalyst concentration, polymerization time, and temperature on the number average molecular weight (Mn) and molecular weight distribution (Mw/Mn) of the copolymers was investigated. The polymerizations were carried out in bulk at 110 °C with 3 wt % stannous octoate as a catalyst for 16 h. The poly(ester‐carbonate)s obtained were characterized by Fourier transform infrared spectroscopy, 1H NMR, differential scanning calorimetry, and gel permeation chromatography. The copolymers synthesized exhibited moderate molecular weights (Mn = 6000–14,700 g mol−1) with reasonable molecular weight distributions (Mw/Mn = 1.11–2.23). The values of the glass‐transition temperature (Tg) of the copolymers depended on the molar fractions of cyclic carbonate. When the MBC content decreased from 76 to 12 mol %, the Tg increased from 16 to 48 °C. The relationship between the poly(N‐CBz‐Hpr‐co‐MBC) Tg and the compositions was in approximation with the Fox equation. In vitro degradation of these poly(N‐CBz‐Hpr‐co‐MBC)s was evaluated from weight‐loss measurements and the change of Mn and Mw/Mn. Debenzylation of 3 by catalytic hydrogenation led to the corresponding linear poly(ester‐carbonate), 4, with pendent amino and carboxylic groups. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2303–2312, 2004
Facile synthesis of AB2‐type miktoarm star polymers through the combination of atom transfer radical polymerization and ring‐opening polymerization
Authors: Erdogan T. , Ozyurek Z. , Hizal G. , Tunca U.
Published: April 2004

A novel miktofunctional initiator (1), 2‐hydroxyethyl 3‐[(2‐bromopropanoyl)oxy]‐2‐{[(2‐bromopropanoyl)oxy]methyl}‐2‐methyl‐propanoate, possessing one initiating site for ring‐opening polymerization (ROP) and two initiating sites for atom transfer radical polymerization (ATRP), was synthesized in a three‐step reaction sequence. This initiator was first used in the ROP of ϵ‐caprolactone, and this led to a corresponding polymer with secondary bromide end groups. The obtained poly(ϵ‐caprolactone) (PCL) was then used as a macroinitiator for the ATRP of tert‐butyl acrylate or methyl methacrylate, and this resulted in AB2‐type PCL–[poly(tert‐butyl acrylate)]2 or PCL–[poly(methyl methacrylate)]2 miktoarm star polymers with controlled molecular weights and low polydispersities (weight‐average molecular weight/number‐average molecular weight < 1.23) via the ROP–ATRP sequence. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2313–2320, 2004
Distinguish protein decoys by Using a scoring function based on a new AMBER force field, short molecular dynamics simulations, and the generalized born solvent model
Authors: Lee Mathew C. , Duan Yong
Published: April 2004

Recent works have shown the ability of physics‐based potentials (e.g., CHARMM and OPLS‐AA) and energy minimization to differentiate the native protein structures from large ensemble of non‐native structures. In this study, we extended previous work by other authors and developed an energy scoring function using a new set of AMBER parameters (also recently developed in our laboratory) in conjunction with molecular dynamics and the Generalized Born solvent model. We evaluated the performance of our new scoring function by examining its ability to distinguish between the native and decoy protein structures. Here we present a systematic comparison of our results with those obtained with use of other physics‐based potentials by previous authors. A total of 7 decoy sets, 117 protein sequences, and more than 41,000 structures were evaluated. The results of our study showed that our new scoring function represents a significant improvement over previously published physics‐based scoring functions. Proteins 2004. © 2004 Wiley‐Liss, Inc.
Is histoaspartic protease a serine protease with a pepsin‐like fold?
Authors: Andreeva N. , Bogdanovich P. , Kashparov I. , Popov M. , Stengach M.
Published: April 2004

The primary structure of the so‐called histoaspartic protease from Plasmodium falciparum has a very high percentage of identity and homology with the pepsin‐like enzyme plasmepsin II. A homology modeling approach was used to calculate the three‐dimensional structure of the enzyme. Molecular dynamics (MD) simulations were applied to find those structural properties of the histoaspartic protease that had a tendency to remain stable during all runs. The results have shown that hydrogen‐bonded residues Ser37–His34–Asp214 are arranged without any strain, in a manner that resembles the active site of a serine protease, while Ser38 and Asn39 take up positions appropriate to formation of an oxyanion hole. Although there are several important differences between the enzyme and plasmepsin II, all of the structural features associated with a typical pepsin‐like aspartic protease are present in the final model of the histoaspartic protease. A possibility that this enzyme may function as a serine protease is discussed. Proteins 2004. © 2004 Wiley‐Liss, Inc.
The low barrier hydrogen bond (LBHB) proposal revisited: The case of the Asp ··· His pair in serine proteases
Authors: Schutz Claudia N. , Warshel Arieh
Published: April 2004

The fact that hydrogen bonds (HBs) can provide major stabilization to transition states (TSs) of enzymatic reactions is well known. However, the nature of HB stabilization has been the subject of a significant controversy. It is not entirely clear if this stabilization is associated with electrostatic effects of preorganized dipoles or with delocalized resonance effects of the so‐called low barrier hydrogen bond (LBHB). One of the best test cases for the LBHB proposal is the complex of chymotrypsin and trifluoromethyl ketone (TFK). It has been argued that the pKa shift in this system provides an experimental evidence for the LBHB proposal. However, this argument could not be resolved by experimental studies. Here we explore the nature of the Asp102–His57 pair in the chymotrypsin‐TFK complex by a systematic computational and conceptual study. We start by defining the LBHB proposal in a unique energy‐based way. We show that a consistent analysis must involve a description in terms of the energy of the two resonance structures and their mixing. It is clarified that LBHBs cannot be defined according to strength or distance, because ionic HBs can also be strong and short. Similarly, NMR chemical shifts and fractionation factors cannot be used to identify LBHBs in a conclusive way. It is also clarified that HBs with a significant asymmetry cannot be classified as LBHBs, because this contradicts the assumption of equal pKa of the donor and acceptor. Thus, the main issue is the ΔpKa and the corresponding energy difference. With this definition in mind, we calculate the free energy surface of proton transfer in this pair and evaluate the energetics of the different ionization states of this system. The calculations are done by both the semimacroscopic version of the protein dipoles Langevin dipoles (PDLD/S‐LRA) model and by the empirical valence bond (EVB) method. The calculations establish that the LBHB proposal is not valid in the chymotrypsin‐TFK complex and in other serine proteases. Although previous theoretical studies reached similar conclusion, this is the first time that the same set of free energy calculations reproduce all the known pKa values and pKa changes in the system, while evaluating the energetics and covalent character of the His–Asp system. The present study provides a support to the idea that enzymes work by creating a preorganized polar environment. Proteins 2004. © 2004 Wiley‐Liss, Inc.
Structure‐based prediction of DNA‐binding sites on proteins Using the empirical preference of electrostatic potential and the shape of molecular surfaces
Authors: Tsuchiya Yuko , Kinoshita Kengo , Nakamura Haruki
Published: April 2004

Protein–DNA interactions play an essential role in the genetic activities of life. Many structures of protein–DNA complexes are already known, but the common rules on how and where proteins bind to DNA have not emerged. Many attempts have been made to predict protein–DNA interactions using structural information, but the success rate is still about 80%. We analyzed 63 protein–DNA complexes by focusing our attention on the shape of the molecular surface of the protein and DNA, along with the electrostatic potential on the surface, and constructed a new statistical evaluation function to make predictions of DNA interaction sites on protein molecular surfaces. The shape of the molecular surface was described by a combination of local and global average curvature, which are intended to describe the small convex and concave and the large‐scale concave curvatures of the protein surface preferentially appearing at DNA‐binding sites. Using these structural features, along with the electrostatic potential obtained by solving the Poisson–Boltzmann equation numerically, we have developed prediction schemes with 86% and 96% accuracy for DNA‐binding and non‐DNA‐binding proteins, respectively. Proteins 2004. © 2004 Wiley‐Liss, Inc.
DRESS: a database of REfined solution NMR structures
Authors: Nabuurs Sander B. , Nederveen Aart J. , Vranken Wim , Doreleijers Jurgen F. , Bonvin Alexandre M.J.J. , Vuister Geerten W. , Vriend Gert , Spronk Christian A.E.M.
Published: April 2004

Several studies have shown that biomolecular NMR structures are often of lower quality when compared to crystal structures, and consequently they are often excluded from structural analyses. We present a publicly available database of re‐refined NMR structures, exhibiting significantly improved quality. This database (available at http://www.cmbi.kun.nl/dress/) presents a uniformly refined and validated set of structural models that improves the value of these NMR structures as input for experimental and theoretical studies in many fields of research. Proteins 2004. © 2004 Wiley‐Liss, Inc.
Primary events in dim light vision: a chemical and spectroscopic approach toward understanding protein/chromophore interactions in rhodopsin
Authors: Fishkin Nathan , Berova Nina , Nakanishi Koji
Published: April 2004

The visual pigment rhodopsin (bovine) is a 40 kDa protein consisting of 348 amino acids, and is a prototypical member of the subfamily A of G protein‐coupled receptors (GPCRs). This remarkably efficient light‐activated protein (quantum yield = 0.67) binds the chromophore 11‐cis‐retinal covalently by attachment to Lys296 through a protonated Schiff base. The 11‐cisgeometry of the retinylidene chromophore keeps the partially active opsin protein locked in its inactive state (inverse agonist). Several retinal analogs with defined configurations and stereochemistry have been incorporated into the apoprotein to give rhodopsin analogs. These incorporation results along with the spectroscopic properties of the rhodopsin analogs clarify the mode of entry of the chromophore into the apoprotein and the biologically relevant conformation of the chromophore in the rhodopsin binding site. In addition, difference UV, CD, and photoaffinity labeling studies with a 3‐diazo‐4‐oxo analog of 11‐cis‐retinal have been used to chart the movement of the retinylidene chromophore through the various intermediate stages of visual transduction. © 2004 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 4: 120–135; 2004: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20000
Selective aerobic oxidation of hydroxy compounds catalyzed by photoactivated ruthenium‐salen complexes (selective catalytic aerobic oxidation)
Authors: Irie Ryo , Katsuki Tsutomu
Published: April 2004

Selective oxidation of alcohols to the corresponding carbonyl compounds is one of the most fundamental reactions in organic synthesis. Traditional methods for this transformation generally rely on stoichiometric amount of oxidants represented by Cr(VI) or DMSO reagents, though their synthetic utility is encumbered by unpleasant waste materials. From ecological and atom‐economic viewpoints, catalytic aerobic oxidation is much more advantageous because molecular oxygen is ubiquitous and the byproduct is basically non‐toxic water or hydrogen peroxide. On the other hand, phenol derivatives undergo oxidative coupling, forming CC or CO bond, through radical intermediates coupled with an electron‐transfer process. Molecular oxygen is also well known to serve as electron acceptor in this reaction. Thus, a variety of transition metal complexes have so far been examined for aerobic oxidations of alcohols and phenols, and high catalytic activities have been achieved in some cases. However, stereo‐ and chemo‐selective aerobic oxidations are still limited in number and are of current interest. Presented in this paper is our recent studies on catalytic aerobic oxidations with photoactivated nitrosyl ruthenium‐salen complexes, including asymmetric oxidation of secondary alcohols to ketones (kinetic resolution), enantioselective oxidative coupling of 2‐naphthols to binaphthols and oxygen‐radical bicyclization of 2,2′‐dihydroxystilbene, chemoselective oxidation of primary alcohols to aldehydes and diols to lactols, and asymmetric desymmetrization of meso‐diols to lactols. © 2004 The Japan Chemical Journal Forum and John Wiley & Sons, Inc. Chem Rec 4: 96–109; 2004: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20001
Prenatal sonographic appearance of congenital bile duct dilatation associated with renal‐hepatic‐pancreatic dysplasia
Authors: Boopathy Vijayaraghavan S. , Kamalam M. , Raman M. L.
Published: April 2004

We report the prenatal sonographic features of congenital bile duct dilatation associated with renal‐hepatic‐pancreatic dysplasia. The condition was seen at 22 weeks of gestation and led to termination of pregnancy. This is the first description of congenital bile duct dilatation using prenatal sonography. It is also the first report of a case in which the features of dysplasia were evident in all three of the organs which may be affected, the kidneys, liver and pancreas. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Dünne ITO‐Schichten als leitfähige, transparente Elektroden. Thin films of ITO as conductive, transparent electrodes
Authors: Mergel Dieter
Published: April 2004

This article deals with materials science aspects of In2O3:Sn (“ITO”) coatings and with the process technology of variants of sputtering used to obtain thin films with properties desired for specific applications. As an example, antistatic and antireflective coatings of monitor tubes are presented. The influence of sputter parameters such as substrate temperature, plasma excitation mode, sputter pressure and oxygen partial pressure on the quality of the films is discussed. It is shown how application‐oriented basic research helps to obtain recipes for materials design. Two basic aspects are discussed in more detail: the influence of an oxygen surplus in the films on microstructure and electrical properties and the correlation of electrical and optical parameters of the films.
New Turbomolecular Pump with Central Opening for Free Axial Access. Eine neue Turbomolekularpumpe mit zentraler Öffnung für freien axialen Zugang
Authors: Mokler P.H.
Published: April 2004

Standard Turbomolekularpumpen haben typischerweise eine kreisringförmige Ansaugöffnung auf der Hochvakuumseite (single‐flow pumps). Die zentrale innere Kreisfläche des Kompressoreingangs der Turbine ist inaktiv für den Pumpvorgang. Das neue Design schlägt eine zentrale Öffnung der Turbomolekularpumpe entlang der ganzen Achse vor. Die zentrale Öffnung kann zur Montage von Durchführungen, Manipulatoren, Fenstern usw. beziehungsweise zum Anschluss weiterer Vakuumeinrichtungen benutzt werden; insbesondere können auch rohrförmige Vakuumsysteme umschlossen werden. Das neue Design erlaubt ein mehrfaches Benutzen eines Pumpflansches einer Vakuumapparatur ohne dort die Pumpleistung zu reduzieren. Außerdem ist das vorgeschlagene Design ideal geeignet für axiale oder radiale differentielle Pumpanordnungen wie sie beispielsweise für alle Gasjet‐ähnlichen Apparaturen oder andere Druckreduktionsstufen benötigt werden.
Die Geschichte der Vakuumkühlung. The History of Vacuum Refrigeration
Authors: Bürger Heinz‐Dieter
Published: April 2004

Die Ausnutzung der hohen Verdampfungsenthalpie des Wassers zum Abkühlen und somit Frischhalten von Lebensmitteln ist eine der ältesten, von Menschen eingesetzten Technologien überhaupt. Sie könnte eigentlich ihren 5000. Jahrestag feiern. Die Kühlung durch Verdunsten von Wasser von feuchten Oberflächen nennen wir heute adiabatische Kühlung, diese reguliert z. B. unsere Körpertemperatur beim Schwitzen. Vor 250 Jahren begann nach Einführung einiger Vakuumpumpen in den wissenschaftlichen Experimentalbetrieb in Grossbritannien die moderne Form der “künstlichen” Kühlung, die Verdampfung von Flüssigkeiten unter Abwesenheit von Permanentgasen im Vakuum. Die Vakuumkühlung mit Wasser als Kältemittel wurde ab 1850, also vor ca. 150 Jahren, nahezu jäh gestoppt, durch die Entwicklung von Kompressions‐Kältemaschinen. Seit Ende des 2. Weltkriegs begann eine Wiedereinführung der Vakuumkühlung, und nun, zu Beginn des 2. Jahrtausends stehen die Chancen gut, verlorenes Terrain wieder gutzumachen.
Simulations of censoring effect in XRF analysis
Authors: Kubala‐Kukuś A. , Pajek M.
Published: April 2004

The quantitative aspects of a use of random left‐censoring as a statistical approach accounting for the detection limit effects in x‐ray fluorescence (XRF) analysis were investigated using the Monte Carlo simulations. More precisely, the performance of the Kaplan–Meier method applied to the estimation of the original concentration distributions from detection limit censored concentration measurements are discussed. The simulations were performed for assumed log‐normal and log‐stable concentration distributions, which are known to model fairly well both concentrations and detection limits for biomedical and environmental samples. In particular, the question of the accuracy of the estimation of the mean value and median for the discussed concentration distributions using the Kaplan–Meier estimator was addressed. It is demonstrated that both the mean value and median of the concentration distribution can be estimated from censored data fairly precisely, typically within 4% for the log‐normal and within 15% for log‐stable models, even for substantial censoring levels (up to 80%). Moreover, the estimation of the median is much more precise than that of the mean value, in particular for stable distributions. Finally, the simulations show that random left‐censoring can be recommended as a standard tool for analysing the detection limit censored concentration measurements of trace elements in XRF analysis. Copyright © 2004 John Wiley & Sons, Ltd.
Random left‐censoring: a statistical approach accounting for detection limits in x‐ray fluorescence analysis
Authors: Pajek M. , Kubala‐Kukuś A. , Banaś D. , Braziewicz J. , Majewska U.
Published: April 2004

The use of x‐ray fluorescence techniques (XRF, TXRF, µXRF) in studies of trace element concentrations is limited by the detection limits (DL) of these methods. In this work we demonstrate that concentration measurements below the DL level, the so‐called ‘non‐detects’, can be included in data analysis by using the statistical concept of ‘censoring’, which is widely used, for instance, in survival analysis. This paper describes the non‐parametric methods of analysis of censored data using the random left‐censoring formalism, which can be used to account for the detection limits in XRF analysis. In particular, the application of the Kaplan–Meier and Nelson–Aalen estimators for the estimation of concentration distributions under censoring is discussed. These approaches are compared with the ‘reconstruction method’ developed earlier in our group to correct XRF data for the effect of detection limits. By using Monte Carlo simulations, the accuracy of the Kaplan–Meier and Nelson–Aalen estimators for censored data is discussed, in particular in the context of the estimation of the mean value and median of a concentration distribution. We demonstrate that for the ‘two‐group’ comparison of left‐censored concentrations, which is a problem of great practical importance, the log‐rank test can be used. The idea of random left censoring is applied to analyse the TXRF detection limit‐censored measurements of the concentrations of trace elements in biomedical samples. Copyright © 2004 John Wiley & Sons, Ltd.
A modular system for XRF and XRD applications consisting of a microfocus X‐ray source and different capillary optics
Authors: Bjeoumikhov A. , Langhoff N. , Rabe J. , Wedell R.
Published: April 2004

In recent years, new components for x‐ray analysis have been developed: capillary optics, microfocus x‐ray tubes and compact detectors, e.g. energy‐dispersive detectors without liquid nitrogen cooling. Microfocus tubes have a relatively low power but their brightness is up to 100 times higher than for normal x‐ray tubes which are used in diffractometry. A combination of these tubes with highly efficient capillary optical elements allows one to obtain parallel or focused beams of high intensity. Combining such a special source with detectors of different kinds, a compact system can be realized which may be successfully used in micro‐XRF, in diffraction and microdiffraction, etc. The system presented is designed in a modular way so that the components may be replaced by each other. Some examples of applications of such systems are reported. Copyright © 2004 John Wiley & Sons, Ltd.
EPMA and µ‐SRXRF analysis and TEM‐based microstructure characterization of a set of Roman glass fragments
Authors: Fredrickx P. , De Ryck I. , Janssens K. , Schryvers D. , Petit J.‐P. , Döcking H.
Published: April 2004

A set of Roman glass fragments, excavated at Bliesbruck–Reinheim (French–German border), were analysed by electron probe microanalysis (EPMA) and micro‐synchrotron radiation‐induced x‐ray fluorescence (µ‐SRXRF) in order to determine the major, minor and trace chemical composition. Based on this analysis, five classes of mono‐coloured glass could be discerned. However, one piece of this set was not mono‐coloured, but consisted of a mixture of brown and white opaque glass. This fragment was investigated using EPMA and transmission electron microscopy (TEM) in order to gain a better insight into its microstructure. Both colours proved to contain small crystalline inhomogeneities. Structural information reveals the form in which the detected elements are present and helps to explain the appearance (e.g. colour) of the material. Copyright © 2004 John Wiley & Sons, Ltd.