A view from the Nijmegen PACS project.

A view on PACS is given from a radiology department involved in PACS as part of its medical research environment. Special attention is payed to historical developments in medical imaging to study the context of actual PACS developments. Some directions of future diagnostic developments are indicated. Both image data-acquisition and presentation techniques are of interest to medical as well as industrial applications. It is pointed out how PACS is thought to depend on contextual factors.

PACS in practice: on-line communications in daily routine.

After a preparatory phase in which a software link was realized, on-line communications between a diagnostic reporting console and a computed tomography (CT) apparatus were set-up. Two specific groups of CT investigations were selected to be diagnosed in a 'digital' as well as a 'conventional' manner. The 'digital' diagnosis implies medical as well as organizational aspects. The latter will be illustrated by an organization study based on activity diagrams performed to set-up a prototype digital archive (PDA). The PDA was developed to determine the information to be stored in a digital archive and the requirements that users have in accessing image data and corresponding attributes. First experiences with respect to the organizational aspects of this clinical picture archiving and communication systems (PACS) project, in which on-line communications are used in daily routine, will be presented.

PACS in practice: the status of the PACS project at the St. Radboud University Hospital. Part A: Introduction and the picture system.

A so-called bottom-up approach of a Picture Archiving and Communication System (PACS) is initiated by existing clinical questions. It is investigated how far existing Data-Acquisition (DA) modalities combined with the existing computer infrastructure of the hospital can provide soil to a, at first local, PACS system. Examples of current research projects in Digital Subtraction Angiography (DSA), Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) demonstrate how image and raw data processing evolve from applications based on a general matrix manipulation software package to projects within the field of PACS. Starting from the existing facilities a stepwise increase of connections and expansions of required features is going to be brought about by separately considering the picture system, the communication system and the archive system. A three step phasing is proposed: (1) Software linking; (2) Hardware linking: small scale; and (3) Hardware linking: local area network. Examples are given from the first phase, i.e. the development and expansion of software on existing DA-modalities or processing hardware to receive the data on floppy disk, hard disk or tape. Data are converted and transported for further processing: (a) within the department; (b) between hospital departments; and (c) between research centres. With regard to the picture system special attention has to be given to the requirements for digitizing analogue film images and the reading of images from monitor screens instead of films on lightboxes.

Structure elucidation of two isomeric steroids: photolytical and thermal reaction products from norethisterone studied by two-dimensional nuclear magnetic resonance.

Two-dimensional nuclear magnetic resonance was used for the structure elucidation of two isomeric photoproducts of norethisterone, a commonly used progestogen in oral contraceptives. The predominant one of the two isolated products derived from photochemical decomposition of norethisterone upon irradiation with UV-B light (280-320 nm) was 5 alpha, 17 beta-dihydroxy-19-nor-17 alpha-pregn-20-yn-3-one. The minor photoproduct appeared to be the analogous 5 beta-isomer, i.e. 5 beta, 17 beta-dihydroxy-19-nor-17 alpha-pregn-20-yn-3-one. The latter compound was also obtained from the thermal reduction of norethisterone-4 beta, 5 beta-epoxide using aluminium amalgam in isopropanol. Two-dimensional NMR appeared to be superior to mass and IR spectrometry in identifying the isomers.

The photochemical decomposition of the progestogenic 19-norsteroid, norethisterone, in aqueous medium.

Norethisterone, a contraceptive 19-norsteroid, was decomposed in aqueous medium (pH 7.4) by UV-B radiation (280-320 nm). This 4-en-3-oxo-19-norsteroid was not prone to the skeletal rearrangement reactions usually observed in steroids possessing a C10-methyl group. Under the reaction conditions applied, products were formed by addition of molecules, such as solvent molecules or a second steroid molecule, and by reduction of the double bond. The prevalence of addition type reactions may have consequences for the application of norethisterone-like steroids in subdermal contraceptive devices.

Derivatives of methanopterin, a coenzyme involved in methanogenesis.

Degradational studies of methanopterin, a coenzyme involved in methanogenesis, are reported. The results of these studies are in full accordance with the proposed structure of methanopterin as N-[1'-(2''-amino-4''-hydroxy-7'' -methyl-6''-pteridinyl)ethyl]-4-[2', 3', 4', 5'-tetrahydroxypent-1'-yl(5'-1'' )O-alpha-ribofuranosyl-5''-phosphoric acid] aniline in which the phosphate group is esterified with alpha-hydroxyglutaric acid. Acid hydrolysis of methanopterin cleaved the 5'----1'' glycosidic bond and yielded a 'hydrolytic product' which was identified as N-[1'-(2''-amino-4''-hydroxy-7'' -methyl-6''-pteridinyl)ethyl]-4-[2', 3', 4', 5'-tetrahydroxypent-1'-yl]aniline. Alkaline permanganate oxidation of methanopterin yielded 7-methylpterin-6-carboxylic acid. Catalytic (or enzymatic) hydrogenation of methanopterin gave a mixture of 6-ethyl-7-methyl-7,8-dihydropterin, 6-ethyl-7-methylpterin and a third compound, named methaniline which was identified as 4-[2', 3', 4', 5'-tetrahydroxypent-1'-yl(5'----1'')O-alpha -ribofuranosyl-5''-phosphoric acid]aniline, in which the phosphate group is esterified with alpha-hydroxyglutaric acid. Methanosarcina barkeri contains a closely related coenzyme called sarcinapterin, which was identified as a L-glutamyl derivative of methanopterin, where the glutamate moiety is attached to the alpha-carboxylic acid group of the alpha-hydroxyglutaric acid moiety of methanopterin via an amide linkage.

Elucidation of the structure of methanopterin, a coenzyme from Methanobacterium thermoautotrophicum, using two-dimensional nuclear-magnetic-resonance techniques.

Methanopterin is a coenzyme involved in methanogenesis. From 2 kg wet cells of Methanobacterium thermoautotrophicum about 35 mumol methanopterin were isolated. The structure of this compound was elucidated by various two-dimensional nuclear-magnetic-resonance techniques. Methanopterin was identified as N-[1'-(2"-amino-4"-hydroxy-7" - methyl-6"- pteridinyl) ethyl]-4-[2',3',4',5'- tetrahydroxypent-1'- yl (5' leads to 1") O-alpha-ribofuranosyl-5"-phosphoric acid] aniline, in which the phosphate group is esterified with alpha-hydroxyglutaric acid. The molecular formula of the sodium salt of methanopterin at pH 7.0 is C30H38O16N6PNa3 X chiH2O (chi is about 4). The anhydrous sodium salt of methanopterin has a molecular mass of 838.60 Da and the molar absorption coefficient at 342 nm is 7.4 mM-1 cm-1 at pH 7.0.