Secondary structure composition and pH-dependent conformational changes of soluble recombinant HLA-DM

HLA-DM catalyzes the release of invariant chain fragments from newly synthesized major histocompatibility complex (MHC) class II molecules, stabilizes empty class II molecules, and edits class II-associated peptides by preferentially releasing those that are loosely bound. The ability of HLA-DM to carry out these functions in vitro is pH dependent, with an optimum at pH 4.5-5.5 and poor activity at pH 7. The structural basis for these properties of HLA-DM is unknown. Sequence homology suggests that HLA-DM resembles classical, peptide-binding MHC class II molecules. In this study, we examined whether HLA-DM has a secondary structure composition consistent with an MHC fold and whether HLA-DM changes conformation between pH 5 and pH 7. Far-UV circular dichroism (CD) spectra of recombinant soluble HLA-DM (sDM) indicate that HLA-DM belongs to the alpha/beta class of proteins and structurally resembles both MHC class I and class II molecules. The CD peak around 198 nm increases upon going from neutral to endosomal pH and drops sharply upon denaturation below pH 3.5, distinguishing at least three states of sDM: the denatured state and two highly similar folded states. Fluorescence emission spectra show a slight blue-shift and a approximately 20% drop in intensity at pH 5 compared with pH 7. Unfolding experiments using guanidinium chloride show that the stability of sDM is somewhat reduced but not lost at pH 5. These results indicate that sDM undergoes a pH-dependent conformational change between neutral and endosomal pH. The change seems to involve both hydrogen bonding patterns and the hydrophobic core of sDM and may contribute to the pH dependence of DM activity.     

Copper-based materials formed by high rate sputtering

This paper presents the results of microstructure and property determinations made on pure and alloyed copper sputter deposited at rates of 20–25 nm s^-1. For each material, the effects of substrate temperature and post-deposition annealing on the grain size and tensile properties were investigated. Fully dense coherent structures were obtained at all substrate temperatures. The absence of the porous poorly bonded structures obtained at temperatures in the range 0.1–0.2T_m by other workers is attributed to the low gas pressure, the normal incidence adatoms and the polished substrates used in the present study.All materials exhibited high tensile strenghts when deposited at 0.2T_m Values of 700 MPa were observed with pure copper, while precipitation-hardening and dispersion-hardening alloys produced values of 1000MPa. The principal difference between these materials was in the stability of their as-deposited structure and their strength during post-deposition annealing. For example, pure copper was unstable to recrystallization at room temperature (0.2T_m), while the dispersion- strengthened alloys exhibited only minor softening at 0.8T_m and very little grain growth at 0.95T_m. The mechanical properties are discussed in relation to the microstructure produced by high rate deposition.     

An improved microcomputer program for finding gene- or gene family-specific oligonucleotides suitable as primers for polymerase chain reactions or as probes.

We present here an easy-to-use computer program which finds oligonucleotides suitable as primers in polymerase chain reactions (PCR) or as probes for hybridization. In contrast to other programs used for this purpose, the additional advantage of this one is the possibility of directly detecting gene- as well as gene family-specific oligonucleotides. For this purpose, up to 200 different DNA sequences, of maximally 65,000 nucleotides each, can be scanned in a single search to ensure either single or multiple gene binding of the PCR primers or probes. Specific oligonucleotides for genes carrying internal repetitions and for single genes belonging to a set of highly conserved genes can also be detected. Many parameters such as exclusion of simple sequences, which are known to be highly repeated throughout various genomes or regions of stable secondary structures in both primer-primer and primer-template, can be taken into consideration and avoided. Furthermore, the G + C content and the length of the oligonucleotides can be changed in a broad range by the user.     

Reply to "Commentary on the special section".

Replies to comments by K. Marshall, S. A. Mitchell, and C. Spezzano (see records 83-14401, 83-14402, and 83-14404, respectively) on the Special Section of Psychoanalytic Psychology, Vol 12(1), on "Contemporary structural psychoanalysis and relational psychoanalysis" and on the article by F. Busch (see record 1995-34118-001). The author expresses concern that most of the commentary failed to see his attempt to open a dialog between the respective adherents of structural and relational psychoanalysis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Study of human isoursodeoxycholic acid metabolism

BACKGROUND/AIMS: The aim of this study was to examine the metabolism of isoursodeoxycholic acid (isoUDCA) in humans. METHODS: IsoUDCA was synthesized of >99% purity and administered orally for 1 week, 3 x 250 mg/day, to six healthy male subjects. Bile acids were extracted from duodenal bile, serum, and 24-h urine samples collected before and at the end of the study period, separated into groups of conjugates, and analyzed by gas chromatography-mass spectrometry and fast atom bombardment mass spectrometry. RESULTS: IsoUDCA was tolerated without any side effect. Liver function tests did not change. Bile acid concentrations (mean+/-SEM) increased from 11.9+/-1.87 to 15.3+/-1.37 mmol/l in bile (n.s.), and from 3.4+/-0.10 to 6.8+/-0.43 micromol/l in serum (p<0.05). Urinary excretion of bile acids increased from 5.3+/-0.29 to 82.2+/-7.84 micromol/24 h (p<0.01). All changes were due to significant increases of isoUDCA and UDCA in bile, serum and urine, and of 3-dehydro-UDCA, the 3-oxo intermediate of isomerization, in bile and in serum. The relative enrichments of isoUDCA, UDCA, and 3-dehydro-UDCA, were: in bile, 2.2%, 25.7%, and 0.7%; in serum, 24.7%, 23.5%, and 6.1%; and in urine, 83.7%, 2.0%, and 2.4%. Whereas 78% of serum isoUDCA was unconjugated, 93-94% of biliary and urinary isoUDCA was conjugated with N-acetylglucosamine. CONCLUSIONS: This study indicates good tolerance and significant intestinal absorption of orally administered isoUDCA. IsoUDCA is extensively isomerized, probably both by intestinal and hepatic enzymes to yield UDCA which became the major biliary compound. In vitro, using the human hepatoblastoma cell line Hep G2, isoUDCA was found to be cytoprotective towards ethanol-induced cell injuries.     

Psychological comorbidity in patients with alarming chest pain symptoms]

About 1/3 of patients with chest pain undergoing coronary arteriography (CA) have no coronary artery disease (CAD). Individuals with non-CAD chest pain may be younger and more likely to be female; they may express higher degrees of neuroticism. Are those features stable enough to justifi; exclusion from CA if present? To investigate this issue, data on psychodiagnostic parameters (depression, anxiety, somatic complaints) were obtained in patients before this were referred to CA. Inclusion criteria were a chief complaint of chest pain with episodes of angina-like pain at rest, suspicious enough to warrant cardiac catherisation; and no prior history of CAD or other organic heart disease. The sample consisted of 77 patients, recruited from 89 eligible patients. 12 patients were excluded because CA findings were missing for multiple reasons. CA was conducted by Judkins technique. Patients were labeled as CAD (-) if no stenosis were detectable. In 50 (65%) of cases CA findings were positive and in 27 (35%) findings were negative. CAD+ were significantly older (p < 0.05); the superiority in both groups were male. Prevalence of emotional disorders was markedly more pronounced in both groups in comparison to the normal population and to a group of male myocardial infarction survivors. However, those features did not discriminate between the groups. Long acting chest pain was predictive for high degrees of emotional disability (relative risk 5.33; 95% Kl 1.6-61.6; p < 0.012). Chest pain at rest is a major source of anxiety, depression and subsequent somatic preoccupation despite its ischaemic or functional origin. It leads to clinically relevant adjustment disorders in a significant proportion of chest pain patients and triggers emotional disstress. These factors may thus have less impact on risk stratification than expected.     

The integration of process and cost modeling—A powerful tool for business planning

Recent developments in modeling can eliminate much experimental laboratory work and can provide quick answers in a more cost-effective manner. This article presents a brief outline of technical cost modeling, a combination of physical modeling and cost modeling, which may be used to the mutual benefit of both the managerial decision makers and the R&D community within the materials processing field.     

Extended Data Acquisition Support at GSI

The Experiment Data Acquisition and Analysis System (EDAS) of GSI, designed to support the data processing associated with nuclear physics experiments, provides three modes of operation: real-time, interactive replay and batch replay. The real-time mode is used for data acquisition and data analysis during an experiment performed at the heavy ion accelerator at GSI. The computing resources provided by dedicated Experiment Computers are insufficient for the more complex experiments performed today. To meet demands for higher data rates, more computing power and more support for data analysis during an experiment, a distributed system was conceived. The GSI High Speed Data Acquisition Network provides the hardware support for the system; it consists of a number of dedicated Experiment Computers which directly control experiments, a multi-user mainframe which performs the data analysis and data storing for all experiments, and a concentrator to connect all Experiment Computers to the mainframe. Three software sub-systems were designed, one for each component of the distributed system. An experiment may be performed either in Stand Alone Mode, using only the Experiment Computers, or in Extended Mode using all computing resources available. The Extended Mode combines the advantages of the real-time response of a dedicated minicomputer with the availability of computing resources in a large computing environment. This paper first gives an overview of EDAS and presents the GSI High Speed Data Acquisition Network. Data Acquisition Modes and the Extended Mode are then introduced.     

Untersuchungen an chemischen Konservierungsmitteln II. Mitteilung Verfahren zur Bestimmung der antimikrobiellen Wirksamkeit von chemischen Konservierungsmitteln

Zusammenfassung Untersuchungen über den Einfluß unterschwelliger, d. h. die Zellvermehrung zwar hemmender, jedoch nicht völlig verhindernder Konservierungs-mittelkonzentrationen auf die Vermehrung von Hefe haben gezeigt, daß der Verlauf von Wachs tumskurven in enger Beziehung zur angewandten Konservierungsmitteldosis steht. Ebenso besteht ein enger Zusammenhang zwischen der angewandten Konservierungs-mittelkonzentration und der schließlich erreichten Endzelldichte. Diese Beobachtungen führten zur Entwicklung verhältnismäßig einfacher Verfahren zur Konservierungs-mittelbewertung, die in der vorliegenden Arbeit beschrieben werden. Ebenso werden Beispiele für ihre praktische Anwendung gegeben.Wir danken der Deutschen Forschungsgemeinschaft für ihre Unterstützung der vorliegenden Arbeit. — An dieser Stelle sei auch FrauH. Egger unser herzlicher Dank für ihre fleißige Mitarbeit bei der Durchführung der Versuche, ausgesprochen.