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Traditional forging techniques are limited to the manufacture of components from solid materials; tubes may only be formed with a form of internal support to prevent the collapse of the work-material under axial forces. There is, however, the scope for achieving sufficiently large plastic deformation of tubes by injection into a diecavity; the extend of such deformation may be enlarged by preforming. The preform is designed to prevent the onset of one of the previously-identified modes of failure; the geometry of the preform was generated using a finite element model which was conditioned on the basis of a large set of experimental results. This paper discusses the possibility of applying the injection forging process in order to allow the complete forming of a geometrically complex tubular component in a single station. The work is supported by finite element modelling in conjunction with metal experiments in aluminum. Metallographic observations and micro-hardness measurements were performed to validate the approach.

An interface program which makes it possible to animate finite element models of metal forming processes in an “Autodesk 3D Studio” environment is presented. The program converts typical finite element results files for a succession of deformation stages into an ASCII file suitable for loading into “3D Studio”. The interface presented processes two-dimensional models only; it requires that the models are discretized by linear rectangular elements and dies by linear two-noded elements. Conversion of mesh objects is based on the creation of triangular three-dimensional faces structured on a set of vertices which are defined by the node positions in the finite element result file. The program is written in FORTRAN and a glossary of terms and the source listing are included. For axisymmetric cases, guidelines are provided for generating three-dimensional effects. An elaborate example of the operational procedure is given.

A model for the prediction of protein partition coefficients in aqueous two-phase systems has been developed. This model accounts for both charge-independent and electrostatic effects. The determination of nonelectrostatic effects was based on the model of Eiteman and Gainer for uncharged solutes while the electrostatic contribution was computed using TITRA, a program that uses a continuum electrostatic model to treat charge interactions in proteins and considers the effect of pH and ionic strength. The partition coefficients of Fusarium solani pisi recombinant cutinase have been satisfactorily predicted in polyethylene glycol (PEG) 1000 and phosphate aqueous two-phase systems at a pH range of 6.0-9.0. The model failed to predict the enzyme partitioning behavior at pH 4.5.

X-ray diffraction analysis (at 2.1-A resolution) of an acid alpha-amylase from Aspergillus niger allowed a detailed description of the stereochemistry of the calcium-binding sites. The primary site (which is essential in maintaining proper folding around the active site) contains a tightly bound Ca2+ with an unusually high number of eight ligands (O delta 1 and O delta 2 of Asp175, O delta of Asn121, main-chain carbonyl oxygens of Glu162 and Glu210, and three water molecules). A secondary binding site was identified at the bottom of the substrate binding cleft; it involves the residues presumed to play a catalytic role (Asp206 and Glu230). This explains the inhibitory effect of calcium observed at higher concentrations. Neutral Aspergillus oryzae (TAKA) alpha-amylase was also refined in a new crystal at 2.1-A resolution. The structure of this homologous (over 80%) enzyme and additional kinetic studies support all the structural conclusions regarding both calcium-binding sites.

We present an atomic force microscopy (AFM) study of a supported triacylglyceride multilayer phase and its interaction with lipolytic enzyme cutinase from Fusarium solani pisi. The multilayer triacylglyceride phase of coconut oil showed a rippled surface structure in the AFM images. Upon enzymatic degradation of the triacylglyceride phase, the ripple structure vanished rapidly. The apparent catalytic rate constants could be estimated based on the AFM image information. Interestingly, in one sample we observed what we interpret as a recurrent structural collapse of the cavity dug out by the protein. We interpret the cavities seen in the AFM images as molten surfaces or surface holes filled with liquidified phase containing product molecules, which appear transparent during the image recording.

Chronic active gastritis associated with Helicobacter pylori infection is characterized by both a neutrophil and a mononuclear leukocyte infiltrate. While neutrophil functions in relation to H. pylori are well described, the interactions between Helicobacter bacterial factors and monocytes are poorly understood in relation to the mucosal inflammatory process.Sonicates of a clinical strain as well as of a type strain of H. pylori were prepared in vitro. Monocytes from healthy donors were induced to release L-selectin (CD62L), to upregulate the adherence molecules (CD11a, CD11b. CD11c) and to produce toxic oxygen radicals. The inducing activities were assessed by flow cytometry and chemiluminescence.A dose-dependent shedding of CD62L and upregulation of CD11b and CD11c were observed with both bacterial strains as well as PMA and fMLP. CD11a remained unchanged. Activity could be attributed to bacterial factors of both lipopolysaccharide (LPS) and protein characteristics. The alterations observed for CD11b, CD11c and CD62L were induced by the same protein fractions in parallel. suggesting a common component and mechanism of action. A major protein component was urease, although other minor protein bands were found as well. Monoclonal antibodies to CD14-inhibited monocyte inflammatory responses induced by H. pylori sonicate at low concentration, whereas further LPS pierce-matrix reduction was necessary at high sonicate concentrations to reduce monocyte-inducing activity.Monocyte inflammatory activation is induced by H. pylori sonicate components. Factors of both LPS and protein characteristics are involved and an additive effect was demonstrated. Urease appears to be a major component in the protein preparations of highest inducing capacity. Further studies are warranted to assess whether the monocyte activation properties described here are related to the diversity of clinical gastroduodenal outcome for the chronic type B gastritis associated with H. pylori infection.

Solution pH is a determinant parameter on protein function and stability, and its inclusion in molecular dynamics simulations is attractive for studies at the molecular level. Current molecular dynamics simulations can consider pH only in a very limited way, through a somewhat arbitrary choice of a set of fixed charges on the titrable sites. Conversely, continuum electrostatic methods that explicitly treat pH effects assume a single protein conformation whose choice is not clearly defined. In this paper we describe a general method that combines both titration and conformational freedom. The method is based on a potential of mean force for implicit titration and combines both usual molecular dynamics and pH-dependent calculations based on continuum methods. A simple implementation of the method, using a mean field approximation, is presented and applied to the bovine pancreatic trypsin inhibitor. We believe that this constant-pH molecular dynamics method, by correctly sampling both charges and conformation, can become a valuable help in the understanding of the dependence of protein function and stability on pH.

A computer program ('BBReader') was developed which performs an inverse search in the BioMagResBank database. Given (cross) peak positions of a protein, the program searches for atoms with matching chemical shifts and suggests possible assignments for user-specified homo- and heteronuclear one- to three-dimensional COSY- and NOESY-type experiments. It can handle 1H, 13C and 15N spectra. Distance information from PDB files can be utilized for filtering possible NOESY cross peak assignments.

The heat transfer by thermal radiation and conduction in char has been investigated as a part of an effort to model the pyrolysis and gasification of biomass.

This chapter aims to provide a brief review on the enzyme family of lipases and esterases. The sequences, 3D structures and pH dependent electrostatic signatures are presented and analyzed. Since the family comprises more than 100 sequences, we have tried to focus on the most interesting features from our perspective, which translates into finding similarities and differences between members of this family, in particular in and around the active sites, and to identify residues that are partially or totally conserved. Such residues we believe are either important for maintaining the structural scaf-fold of the protein or to maintain activity or specificity. The structure function relationship for these proteins is therefore of central interest. Can we uniquely identify a protein from this large family of sequences--and if so, what is the identifier? The protein family displays some highly complex features: many of the proteins are interfacially activated, i.e. they need to be in physical contact with the aggregated substrate. Access to the active site is blocked with either a loop fragment or an alpha-helical fragment in the absence of interfacial contact. Although the number of known, relevant protein 3D structures is growing steadily, we are nevertheless faced with a virtual explosion in the number of known or deduced amino acid sequences. It is therefore unrealistic to expect that all protein sequences within the foreseeable future will have their 3D structure determined by X-ray diffractional analysis or through other methods. When feasible the gene and/or the amino acid sequences will be analyzed from an evolutionary perspective. As the 3D folds are often remarkably similar, both among the triglyceride lipases as well as among the esterases, the functional diversities (e.g. specificity) must originate in differences in surface residue utilization, in particular of charged residues. The pH variations in the isopotential surfaces of some of the most interesting lipases are presented and a qualitative interpretation proposed. Finally we illustrate that NMR has potential for becoming an important tool in the study of lipases, esterases and their kinetics.

Primary cultures of cerebral cortical GABA-ergic neurons growing on top of a preformed layer of astrocytes (co-cultures) were incubated with [1-13C]glucose and exposed to a low oxygen atmosphere (2% O2) for 17 hr. 13C, 1H, and 31P nuclear magnetic resonance (NMR) spectroscopy was performed on perchloric acid (PCA) extracts of cells and of media collected from these cultures. In the control groups incorporation of 13C label into glutamine, citrate, and lactate could be demonstrated in both cell extracts and culture media. Labeled GABA and glutamate were only observed in cell extracts. During hypoxia high energy phosphates decreased but lactate production and glucose consumption increased. There was a decreased amount of citrate and glutamine in cell extracts and media of the hypoxic co-cultures. There was a change in distribution of the 13C label within the GABA molecule, with an increase of labeling in the C-2 position. This change in 13C distribution was not found in glutamine present in the media where it is a precursor for GABA in neurons. Instead a decrease in the corresponding C-4 position was observed. These results suggest that energy depletion during hypoxia leads to reduced export from the astrocytic tricarboxylic acid (TCA) cycle as demonstrated by a decreased amount of citrate and changed distribution of 13C in glutamine. The change in the distribution of label in GABA from cell extracts as compared to glutamine in the medium may indicate that neurons are synthesizing GABA using precursors supplied from their own TCA cycle and not from precursors supplied by astrocytes.

Nuclear magnetic resonance spectroscopy (MRS) offers a unique opportunity to monitor mmolar concentrations of high energy phosphates, glucose, lactate and amino acids. The possibility of obtaining information about chemical constituents noninvasively is of great importance. MRS and chemical shift imaging (CSI) are emerging as tools for tumor grading, monitoring of treatment, ischemia research, in pediatric research for follow-up of children with borderline mental retardation, for defining brain death and to define epileptic foci. It is important to know which cell type (neuronal or glial) shows changes as a result of external manipulations (e.g. excitotoxins) or internal changes (brain pathology). Metabolic studies have been carried out on brain cell cultures. By using 13C labeled glucose and acetate in combination with 13C MRS it was shown that astrocytes release lactate, glutamine, citrate and alanine and that cerebral cortical neurons use glutamine released from astrocytes as a precursor for GABA synthesis. An important feature in MRS is the localization of N-acetyl aspartate in neurons, since this enables monitoring of neuronal reactions, such as survival after neurotoxic insults. Recent advances have yielded high speed functional echo planar imaging (EPI) techniques that are sensitive to changes in cerebral blood volume, blood flow and blood oxygenation (Functional MRI). During cognitive task performance, local alterations in neuronal activity induce local changes in cerebral metabolism and cerebral perfusion, which can now be detected with MRI.

Proton (1H) nuclear magnetic resonance (NMR) spectra were obtained from perchloric acid (PCA) extracts of 11 breast tumours and non-involved breast tissue from 7 of the same patients. The spectra were correlated with histopathologic diagnosis. The tumour group consisted of 8 ductal carcinomas, 1 ductal carcinoma with an extensive intraductal component, 1 intraductal carcinoma and 1 fibroadenoma. Higher content of lactate, succinate and phosphocholine and low levels of glucose and inositol were characteristic findings in the tumour group as compared to non-involved breast tissue. 1H NMR spectra of PCA extracted breast specimens provide a comprehensive window into the metabolic activities of the tissue.

To describe knowledge, attitude and behaviour regarding AIDS among students and employees at the University of Aarhus an anonymous self-administered questionnaire survey was conducted in April 1990. Of the 2169 and 850 questionnaires to students and employees, respectively, 1548 (71.4%) and 568 (67%) were returned. The study group had an excellent knowledge about AIDS and the transmission of HIV-virus. However, when defining "risk behaviour" in relation to transmission of HIV-virus among heterosexuals as "or = 2 sexual partners within the past year without using condoms" 27% of the male and 20% of the female students showed risk behaviour. Among employees the rate was highest (23%) among the male scientific staff than among the remainder (17%). It is concluded that risk behaviour was not related to age and occurred in spite of the fact that 42% of the students and 31% of the employees, who showed risk behaviour were also aware of a personal risk of being infected. There is still a need for information about AIDS, and future campaigns should be directed towards all age groups as risk behaviour is not only a phenomenon among young people.

Neocortical astrocytes were incubated with 13C-labeled substrates to determine metabolic pathways. 13C NMR spectroscopy was used to analyze 13C incorporation into glutamine and citrate from the different precursors--[1-13C]glucose or [2-13C]acetate. When glucose was the labeling substrate, incorporation due to pyruvate carboxylation should be observed in the C-2 position in glutamine and the C-4 position in citrate. A large incorporation due to pyruvate carboxylation was observed in glutamine in the C-2 and C-3 positions, but not in citrate. When acetate was the precursor, the labeling ratios in the C-2/C-4 positions in glutamine and in the equivalent positions in citrate were 0.27 and 0.11, respectively. Moreover, acetate labeled lactate in the C-2 position much less than did glucose. Altogether, these observations led to the conclusion that glutamine precursors and citrate are either produced in different types of astrocytes or in different tricarboxylic acid cycles, situated in functionally different mitochondria in the same cell, and that in all likelihood pyruvate carboxylase is expressed differently in these mitochondria.

A neural network computer program, trained to predict secondary structure of proteins by exposing it to matching sets of primary and secondary structures from a database, was used to analyze the human immunodeficiency virus (HIV) proteins p17, gp120, and gp41 from their amino acid sequences. The results are compared to those obtained by the Chou-Fasman analysis. Two alpha-helical sequences corresponding to the putative fusigenic domain and to the transmembrane domain of gp41 could be predicted, as well as a possible binding site between p17 and gp41. On the basis of the secondary structure predictions, a three-dimensional model of p17 was constructed. This model was found to represent a stable conformation by an analysis using an energy-minimization program. The model predicts that p17 is attached to the membrane only by the acylated N-terminus, in analogy with the N-terminus of the gag protein of other retroviruses and also with the src oncogene protein p60src. The intracellular C-terminal part of gp41 may act as a receptor by electrostatic interaction with p17.

In order to examine dynamic aspects, including excitations, in \ensuremath{\alpha}-helix structures in proteins, models in three spatial dimensions of \ensuremath{\alpha} helices have been set up and their dynamic behavior examined by numerical computations. The potential-energy function describing the system is based on empirical data and implemented in the molecular-dynamics computer program charmm. Two types of excitations have been examined: lattice vibrations and intramolecular vibrations. The former disperse rapidly while the latter (being essentially amide-I-type vibrations) evolve regularly. A simple model based on a system of coupled linear oscillators can reproduce the time evolution of the intramolecular vibrations.

A three-dimensional model of an \ensuremath{\alpha} helix is built applying a molecular-mechanics approach. The potential-energy function describing the system is based on empirical data and implemented in the molecular-dynamics computer program charmm. The time evolution of amide-I vibrations has been examined numerically. In order to examine the coupling mechanism of an amide-I oscillator to other amide-I oscillators along the backbone as well as along the so-called spines, a simple analytical model has been set up. From this model the coupling along the backbone is estimated to be more than 50% stronger than the coupling along the spines.

Physiologically inert perfluorinated gases may be used for lung ventilation imaging by Nuclear Magnetic Resonance (NMR). Because the nuclear concentration in the gas is lower than in tissue, signals from large gas volumes must be integrated to produce an acceptable image quality. After a series of phantom studies, preliminary dog studies have been carried out, using breathable mixtures of CF4 and O2. The resulting images have been compared with Xe ventilation scans. Furthermore, perfluorinated solutions were imaged using phantoms. The results are described and the future potential of the technique discussed.

First general considerations of the new NMR technique are given. Then disturbing influences on the magnet coming from outside as well as influences upon the environs coming from the magnet are pointed out. Next the inside arrangements of examination rooms are discussed. Finally accessory and emergency equipment for the examination rooms are mentioned.

In vivo synchronized 3D Proton NMR zeugmatographic images of the beating heart have been obtained. The images clearly show the cardiac anatomy and changes in the anatomy accompanying the cardiac cycle. Transverse, coronal and sagittal slices are presented.

NMR tomography (zeugmatography) can provide 2D and true 3D images of the human body. Advantages of this new imaging method in medicine are the possibilities to get both anatomic and functional images at one time without any invasive procedures. Furthermore, NMR has no ionizing radiation hazards. The spacial resolution of NMR tomography ranges between 0.5 and 3.0 mm. Within the next years, NMR tomography will replace several conventional X-ray, CAT scanning and nuclear medicine techniques. This article gives a brief survey of NMR basics and its medical applications.

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