Alternative to Ph. Eur. pour-plate method for detection of microbial contamination in non-sterile pharmaceutical preparations.

The current European Pharmacopoeia (Ph. Eur.) texts for Interferon (IFN)-alfa-2 include a nonspecific photometric protein assay using albumin as calibrator and a highly variable cell-based assay for the potency determination of the protective effects. A request was expressed by the Official Medicines Control Laboratories (OMCLs) for improved methods for the batch control of recombinant interferon alfa-2 bulk and market surveillance testing of finished products, including those formulated with Human Serum Albumin (HSA). A HPLC method was developed at the Medical Products Agency (MPA, Sweden) for the testing of IFN-alfa-2 products. An initial collaborative study run under the Biological Standardisation Programme (BSP; study code BSP039) revealed the need for minor changes to improve linearity of the calibration curves, assay reproducibility and robustness. The goal of the collaborative study, coded BSP071, was to transfer and further validate this improved HPLC method. Ten laboratories participated in the study. Four marketed IFN-alfa-2 preparations (one containing HSA) together with the Ph. Eur. Chemical Reference Substance (CRS) for IFN-alfa-2a and IFN-alfa-2b, and in-house reference standards from two manufacturers were used for the quantitative assay. The modified method was successfully transferred to all laboratories despite local variation in equipment. The resolution between the main and the oxidised forms of IFN-alfa-2 was improved compared to the results from the BSP039 study. The improved method even allowed partial resolution of an extra peak after the principal peak. Symmetry of the main IFN peak was acceptable for all samples in all laboratories. Calibration curves established with the Ph. Eur. IFN-alfa-2a and IFN-alfa-2b CRSs showed excellent linearity with intercepts close to the origin and coefficients of determination greater than 0.9995. Assay repeatability, intermediate precision and reproducibility varied with the tested sample within acceptable ranges. Test accuracy estimated by comparing the values obtained by the participants to the declared contents determined by the manufacturers was good despite the absence of a common reference preparation. In conclusion, the present study showed that the new method is suitable, reproducible and transferable. Proposals for the revision of Ph. Eur. texts are presented.

A new isoleucine substitution of Val-20 in transthyretin tetramers selectively impairs dimer-dimer contacts and causes systemic amyloidosis.

The most frequent form of inherited amyloidoses is associated with mutations in the transthyretin (TTR) gene coding for 127-amino acid residues of four identical, noncovalently linked subunits that form a pair of dimers in the plasma protein complex. Amyloid fibrils containing the variant and to a lesser extent the wild-type form of the TTR molecule are deposited in various organs, including peripheral nerves and the myocardium, with polyneuropathy and cardiomyopathy as major clinical manifestations. So far, more than 40 distinct amino acid substitutions distributed throughout the TTR sequence over 30 positions have been found to be correlated with an increased amyloidogenicity of TTR. Most of these amyloidogenic amino acid substitutions are suspected to alter the conformation and stability of the monomer. Here we identify and characterize by protein and DNA analysis a novel amyloidogenic Val-20 to Ile mutation in a German three-generation family. The index patient suffered from severe amyloid cardiomyopathy at the age of 60. Conformational stability and unfolding behavior of the Ile-20 monomer in urea gradients was found to be almost indistinguishable from that of wild-type TTR. In contrast, tetramer stability was significantly reduced in agreement with the expected change in the interactions between the two opposing dimers via the side chain of Ile-20. Our observations provide strong evidence for the view that amyloidogenic amino acid substitutions in TTR facilitate the conversion of tetrameric TTR complexes into those conformational intermediates of the TTR folding pathway that have an intrinsic amyloidogenic potential.

[Quantitative studies assessing daytime fatigue, vigilance and attention before and after nCPAP therapy of sleep apnea syndrome]. / Quantitative Untersuchungen zur Erfassung der Tagesmüdigkeit, der Vigilanz und der Aufmerksamkeit vor und nach nCPAP-Therapie bei Schlafapnoesyndrom.

As far as day symptoms are concerned, excessive drowsiness and tendency to fall asleep are signposts in diagnosis and treatment of sleep apnoea syndrome exercising a decisive influence on the patient's quality of life. Recent studies (Findley et al., 1988; George et al., 1987; Aldrich et al. 12/89) have shown that the patients are additionally endangered by an increased accident risk. After controversial data in the literature in respect of the usefulness of neuropsychological testing when going into this problem we tried to develop an alternative to MSLT (Multiple Sleep Latency Test) which is the clinical standard, since the technique required is so complicated that it is only rarely used in everyday practice. We aimed at easy application in clinical daily routine. We examined via computer-assisted neuropsychological testing the attention and concentration performance in 14 patients having a sleep apnoea syndrome of moderate severity, before and after a short treatment course of three nights with nCPAP, and compared the results with those obtained in 17 patients with a similar pattern of complaints in whom a sleep apnoea syndrome could be excluded. The test lasted for 45 minutes in each case. Various reaction time tests were performed with acoustical, optical and combined phenomena. The reaction times as well as the number of errors were noted. We could show that the treatment course resulted in an improvement of certain attention and concentration performances, above all however in continuous attention against a monotonous stimulation background (vigilance)--and improvement that can be measured already after a short therapy period.(ABSTRACT TRUNCATED AT 250 WORDS)

Biosynthesis of gallotannins : Enzymatic 'disproportionation' of 1,6-digalloylglucose to 1,2,6-trigalloylglucose and 6-galloylglucose by an acyltransferase from leaves of Rhus typhina L.

Cell-free extracts from leaves of Rhus typhina L. (sumach) were found to transfer the 1-O-galloyl moiety of l,6-di-O-galloyl-ß-D-glucose to the 2-position of the same compound, yielding 1,2,6-tri-O-galloyl-ß-D-glucose and leaving 6-O-galloylglucose as the deacylated by-product. The enzyme catalyzing this 'disproportionation' was purified almost 1700-fold. It had a molecular weight of approx. 56 000, a K m value of 11.5 mM, was stable between pH 4.5 and 6.5, and most active at pH 5.9 and 40° C. The systematic name "1,6-di-O-galloyl-glucose: 1,6-di-O-galloylglucose 2-O-galloyltransferase" (EC 2.3.1.) was proposed for this new enzyme whose detection provided evidence that, in addition to ß-glucogallin (1-O-galloyl-ß-D-glucose), higher substituted glucose esters also have the potential to serve as acyl donors in the biosynthesis of gallotannins.

Biosynthesis of gallotannins: beta-glucogallin-dependent formation of 1,2,3,4,6-pentagalloylglucose by enzymatic galloylation of 1,2,3,6-tetragalloylglucose.

An acyltransferase was detected in young leaves of pedunculate oak (Quercus robur) that catalyzed the formation of 1,2,3,4,6-penta-O-galloyl-beta-D-glucose, the common precursor of gallotannins and the related ellagitannins. This enzyme depended on beta-glucogallin (1-O-galloyl-beta-D-glucose) as acyl donor; 1,2,3,6-tetra-O-galloyl-beta-D-glucose was specifically required as acceptor molecule, whereas no reaction occurred with the 1,2,4,6-isomer of this substrate. The partially purified enzyme (Mr 260,000) was stable between pH 5.0 and 6.5; highest activities were observed at pH 6.3 and 40 degrees C. Km values of 2.3 and 1.0 mM, respectively, were determined for the substrates beta-glucogallin and tetragalloylglucose. In accordance with stoichiometric studies, the systematic name "beta-glucogallin: 1,2,3,6-tetra-O-galloylglucose 4-O-galloyltransferase" is proposed for this new enzyme.

Relapsing pancreatitis as initial manifestation of cystic fibrosis in a young man without pulmonary disease.

In young adults with acute pancreatitis a wide etiologic spectrum has to be considered. Among the possible causes, cystic fibrosis is rare. Besides the typical clinical triad of pancreatic exocrine insufficiency, chronic obstructive pulmonary disease, and elevated sweat chloride levels, there is a wide spectrum of variants of the cystic fibrosis syndrome. Especially mild manifestations of the disease may, therefore, escape proper identification. Here we describe a young man who presented initially with recurrent acute pancreatitis without pulmonary disease and without a family history of cystic fibrosis, in whom the diagnosis of cystic fibrosis was established by slightly elevated sweat chloride levels and obstructive azoospermia. Five years after the first attack of pancreatitis the patient developed pancreatic exocrine insufficiency.

Biosynthesis of gallotannins. Enzymatic conversion of 1,6-digalloylglucose to 1,2,6-trigalloylglucose.

Cell-free extracts from Rhus typhina L. (staghorn sumach) leaves were found to catalyze the transfer of the galloyl moiety of ß-glucogallin (1-O-galloyl-ß-D-glucose) to 1,6-di-O-galloyl-ß-D-glucose, resulting in the specific formation of 1,2,6-tri-O-galloyl-ß-D-glucose, an intermediate of gallotannin biosynthesis. The reaction product was unequivocally identified by co-chromatography with authentic references using reversed-phase high-performance liquid chromatography and by (1)H-nuclear-magnetic-resonance spectroscopy.