Serum IL-17F does not predict poor response to IM IFNß-1a in relapsing-remitting MS.

OBJECTIVE: There is a significant unmet need for serum biomarkers in relapsing-remitting multiple sclerosis (RRMS) that are predictive of therapeutic response to disease-modifying therapies. Following a recent Stanford study which reported that pretreatment levels of serum interleukin (IL)-17F could predict poor response to interferon-ß (IFNß) therapy, we sought to validate the finding using samples from a large clinical trial. METHODS: The validation cohort included 54 good responders (GR) and 64 poor responders (PR) selected from 762 subjects with RRMS from the IM IFNß-1a dose comparison study (Avonex study C94-805). Subjects were classified as GR and PR based on the number of relapses, Expanded Disability Status Scale score, and new and enlarging T2 lesions on MRI. Serum samples were assayed for IL-17F using a multiplexed Luminex assay and for IL-17F/F using an ELISA. Replicate aliquots from the Stanford study were also assayed to assure reproducibility of methods. RESULTS: Median pretreatment and post-treatment serum IL-17F levels were not statistically significantly different between GR and PR, and serum IL-7/IL-17F ratios were also not predictive of response status. Replicate aliquots from the Stanford study showed good correlation to their original cohort (r = 0.77). CONCLUSIONS: We were unable to validate the finding that serum IL-17F is a predictor of PR in a large independent cohort of subjects with RRMS. Differences in patient populations and methodology might explain the failure to validate the results from the Stanford study.

Identification of a yellow impurity in aged samples of aqueous butamben suspension: evidence for the oxidative degradation of poly(ethylene glycol).

Butamben (butyl p-aminobenzoate) has been formulated to provide long-acting treatment for chronic pain. The suspension, which contains poly(ethylene glycol) and polysorbate 80, was found to yellow under ambient conditions if not adequately protected from oxygen. The impurity responsible for the color was isolated and identified on the basis of nuclear magnetic resonance spectroscopy and mass spectrometry. The compound is an oxalamidine, which is formally the condensation product of oxalic acid with four equivalents of butamben, and may be formed by the reaction of butamben with an oxidation product of poly(ethylene glycol).

Metabolism and disposition of the HIV-1 protease inhibitor ritonavir (ABT-538) in rats, dogs, and humans.

The metabolism and disposition of [14C]ritonavir (ABT-538, NOR-VIR), a potent, orally active HIV-1 protease inhibitor, were investigated in male and female Sprague-Dawley rats, beagle dogs, and HIV-negative male human volunteers. Rats and dogs received a 5 mg/kg iv, 20 mg/kg oral or 20 mg/kg intraduodenal dose, whereas humans received a single 600-mg liquid oral dose. Ritonavir was cleared primarily via hepatobiliary elimination in all three species. After iv or oral dosing in either rats or dogs, > 92% of the dose was recovered in rat and dog feces and < or = 4% was recovered in the urine. Humans excreted 86.3% of the oral dose in feces and 11.3% in urine over 6 days. Bile-exteriorized rats and dogs excreted 85.5% and 39.8%, respectively, of the iv dose in bile, with < 3% recovered in urine. Radio-HPLC analysis of bile, feces, and urine from all three species indicated extensive metabolism of ritonavir to a number of oxidative metabolites, some being species-specific, and all involving metabolism at the terminal functional groups of the molecule. Glucuronide metabolites were observed in dog only. Plasma radioactivity consisted predominantly of unchanged parent drug in all three species. M-2, the product of hydroxylation at the methine carbon of the terminal isopropyl moiety of ritonavir, was the only metabolite present in human plasma and made up 30.4% of the total dose recovered in human excreta over 6 days. Tissue distribution of ritonavir in rat was widespread, with good distribution into lymphatic tissue but low CNS penetration. Plasma protein binding of ritonavir was high (96-99.5%) in all species and was nonsaturable in humans at concentrations up to 30 micrograms/ml. Partitioning into the formed elements of whole blood was minimal.

Production of brominated tiacumicin derivatives.

Several novel tiacumicin derivatives containing bromine have been produced by the addition of inorganic bromine to the fermentation both of Dactylosporangium aurantiacum subsp, hamdenensis. Structures were elucidated employing mass spectrometry and NMR spectroscopy. Antibacterial activity of the bromotiacumicins is comparable to that of the parent compounds.

Cytochrome P450-mediated metabolism of the HIV-1 protease inhibitor ritonavir (ABT-538) in human liver microsomes.

The HIV-1 protease inhibitor ritonavir (ABT-538) undergoes cytochrome P450-mediated biotransformation in human liver microsomes to three major metabolites, Ml, M2 and M11, with wide interindividual variation in the rates of metabolite formation. The structures of these metabolites were determined with the use of electrospray ionization mass spectrometry. Chemical inhibition, metabolic correlation, immunoinhibition and metabolism by microsomes derived from specific CYP cDNA-transfected B-lymphoblastoid cell lines indicated that the CYP3A subfamily of enzymes was the major contributor to the formation of M1 and M11, whereas both CYP3A and CYP2D6 contributed to the formation of M2. None of the typical CYP3A substrates/inhibitors (e.g., ketoconazole, troleandomycin) were able to completely inhibit ritonavir metabolism, even at high concentrations. Ritonavir was found to be a potent inhibitor of CYP3A-mediated biotransformations (nifedipine oxidation, IC50) = 0.07 microM; 17alpha-ethynylestradiol 2-hydroxylation, IC50 = 2 microM; terfenadine hydroxylation, IC50 = 0.14 microM). Ritonavir was also found to be an inhibitor of the reactions mediated by CYP2D6 (IC50 = 2.5 microM) and CYP2C9/10 (IC50 = 8.0 microM). The results of this study indicate the potential for in vivo inhibition of the metabolism by ritonavir of drugs that are CYP3A, CYP2D6 and, to a lesser extent, CYP2C9/10 substrates.

HPLC and PDMS analysis of cleavage products aid in the design of small, stable ANP analogues.

The degradation of a prototypical small analogue of atrial natriuretic peptide (ANP) has been studied using HPLC and mass spectrometric techniques. These studies revealed that removal of the N-terminal amino acid was the primary catabolic event in vitro. Based on this information the N-terminus was remanufactured to provide a family of more stable analogues. Additional stabilization was provided through modification of the C-terminal tripeptide. Through dramatically more stable in vitro, these new analogues do not appear to have longer in vivo half-lives.

Dunaimycins, a new complex of spiroketal 24-membered macrolides with immunosuppressive activity. II. Isolation and elucidation of structures.

A novel complex of antifungal and immunosuppressant compounds has been isolated from the fermentation broth and mycelia of two strains of Streptomyces diastatochromogenes. The structures of eight related components were determined employing 1D and 2D homonuclear and the heteronuclear NMR spectroscopy and mass spectrometry. These structures represent the first reported spiroketal 24-membered macrolide natural products related to the common 26-membered oligomycins.

Characterization of a posttranslational fucosylation in the growth factor domain of urinary plasminogen activator.

A posttranslational modification site in natural and recombinant urinary-type plasminogen activators (urokinases; EC 3.4.21.31) has been localized to Thr-18, in the growth factor domain of the molecule. This is the region of urinary plasminogen activator responsible for its specific receptor binding. An unusual carbohydrate-protein linkage, a single monosaccharide, fucose, covalently attached directly to threonine in the peptide, is described here. The glycan moiety and the site of modification have been identified with mass spectrometry and confirmed by carbohydrate composition analysis, Edman degradation, and one- and two-dimensional NMR studies. This type of modification is normally not detected without mass spectrometry because the fucose-threonine bond is hydrolyzed under standard acidic conditions of the amino acid analysis and Edman sequencing. This modification may be widely found in other proteins.

Group B streptococci inactivate complement component C5a by enzymic cleavage at the C-terminus.

Incubation of recombinant human C5a (rC5a) with the 7360 strain of group B streptococci (GBS) destroyed the ability of rC5a to stimulate chemotaxis or adherence of purified human polymorphonuclear leucocytes (PMNs). Treatment of 125I-labelled rC5a with GBS 7360 correspondingly decreased rC5a binding to human PMNs. This also resulted in an approx. 600 Da decrease in the molecular mass of rC5a as determined by SDS/PAGE. Incubation of rC5a with the GBS strain GW, which only minimally altered the ability of rC5a to activate human PMNs, did not affect rC5a binding to PMNs and did not alter the molecular mass of rC5a on SDS/PAGE. Plasma-desorption m.s. of rC5a inactivated by GBS 7360 showed that the GBS cleaved the rC5a between histidine-67 and lysine-68 near the C-terminus of rC5a. This mechanism of inactivation of C5a by proteolytic cleavage at the C-terminus of C5a is consistent with the known critical role of the C-terminus in C5a activation of human PMNs. This C5a-cleaving proteinase activity may contribute to the pathophysiology of GBS infections.

Sequence-specific fragmentation from oligopeptides using plasma-desorption mass spectrometry.

252Cf plasma-desorption mass spectrometry (PDMS) has been demonstrated to provide sequence-specific fragmentation for several oligopeptides. The nature of the fragment ions observed is generally similar to that observed using liquid secondary-ion mass spectrometry (LSIMS) and can be observed using less sample than LSIMS requires, but PDMS spectra are acquired at a lower resolution. In addition, the molecular weight of some of the oligopeptides studied exceeds that which is generally accepted as within the sequence range of LSIMS. The specific series of sequence ions that predominate in the PDMS spectra appear to be related to the amino acid compositions and sequences of the oligopeptides.

Altromycins, novel pluramycin-like antibiotics. II. Isolation and elucidation of structure.

A novel complex of Gram-positive antibiotics was produced from the fermentation of an actinomycete culture AB 1246E-26. The antibiotics were recovered from the whole fermentation broth by extraction with organic solvent and isolated using counter-current chromatography. UV and IR data place these compounds in the anthraquinone-derived class of antibiotics. Mass spectral and NMR data indicate a new complex of compounds related to, but distinctly different from the pluramycin type antibiotics.

Pacidamycins, a novel series of antibiotics with anti-Pseudomonas aeruginosa activity. II. Isolation and structural elucidation.

A novel class of antibiotics was isolated from cultures of Streptomyces coeruleorubidus strain AB 1183F-64. The antimicrobial activity of the pacidamycins is selective against Pseudomonas aeruginosa. The various congeners are nucleoside peptides which differ in the terminal amino acid residues. The structures were determined using MS-MS and 2D NMR techniques.

Coumamidines, new broad spectrum antibiotics of the cinodine type. II. Isolation and structural elucidation.

Two novel, isomeric compounds, coumamidines gamma 1 and gamma 2, were isolated from fermentations of an actinomycete. The structures were elucidated spectroscopically using 2D NMR correlation experiments and mass spectral data. The coumamidines were found to be close structural relatives of the cinodines (LL-BM123 gamma 1 and gamma 2).

Phenelfamycins, a novel complex of elfamycin-type antibiotics. II. Isolation and structure determination.

A novel complex of elfamycin-type antibiotics has been isolated from submerged fermentation of either Streptomyces violaceoniger AB 999F-80 or Streptomyces violaceoniger AB 1047T-33. Antibiotics were extracted from the fermentation broth with ethyl acetate and from the mycelia with acetone. Purification of individual components was achieved by a combination of solvent partitions, Sephadex LH-20 exclusion, C18 bonded-phase silica gel adsorption, diol partition and liquid-liquid countercurrent chromatographies. Seven closely related components were separated and assigned structures 4, 11, 12, 13, 14, and 16 to phenelfamycins A to F respectively and structure 17 to unphenelfamycin. These structures were elucidated employing a variety of spectroscopic techniques, including extensive use of 1D and 2D NMR spectroscopy.

Coloradocin, an antibiotic from a new Actinoplanes. II. Identity with luminamicin and elucidation of structure.

Coloradocin was isolated from a fermentation broth by adsorption onto Amberlite XAD-2. The activity was eluted in MeOH and purified by gel filtration on Shephadex LH-20, followed by liquid-liquid chromatography on diol-bonded silica gel. The last two steps in the purification of this antibiotic included reverse-phase chromatography on C18-bonded silica gel and countercurrent chromatography on an Ito Coil Planet Centrifuge to give material of 90% purity. Analytically pure material was obtained by preparative HPLC. As a result of extensive homo and heteronuclear two-dimensional NMR studies, a structure was proposed for coloradocin. The structure consists of a decalin ring system fused to a 10-membered macrolactone which in turn is fused to a 14-membered macrolactone possessing an enol ether in conjugation with an unsaturated cyclic anhydride functionality. Coloradocin is related to a small class of antibiotics which include nodusmicin and nargenicin and was shown to be identical to luminamicin for which no structure has been reported.

Tiacumicins, a novel complex of 18-membered macrolides. II. Isolation and structure determination.

A novel complex of Gram-positive antibiotics has been isolated from the fermentation broth and mycelium of Dactylosporangium aurantiacum subsp. hamdenesis subsp. nov. The structures of these six compounds were deduced employing UV, MS, IR, and extensive 1D and 2D homonuclear and heteronuclear NMR experiments. Each component contained a highly unsaturated 18-membered macrolide ring. Components differed from one another by minor structural variations in the macrolide ring and by the number and esterification pattern of glycosidically bound sugars.

Peptide studies using a fast atom bombardment high field mass spectrometer and data system. 4. Disulfide-containing peptides.

Ten peptides containing one, two or three disulfides were examined to determine their behavior under fast atom bombardment (FAB) mass spectrometric conditions. The mass spectra for the disulfide and the reduced disulfide forms of each peptide were compared. Several factors were examined that contribute to the fast atom bombardment mass spectra of these peptides: components of the FAB matrix such as alkali cations, acids, bases and reducing agents, the intrinsic molecular properties of the intact peptide, and the effect of reducing conditions on sensitivity. The FAB mass spectra of the disulfide-containing peptides examined in this study displayed accurate molecular weight information and fragmentation which indicated the position of the disulfide in the amino acid sequence.

Peptide studies using a fast atom bombardment high field mass spectrometer and data system. 3--Negative ionization: mass calibration, data acquisition and structural characterization.

Under negative ionization conditions, nominal mass calibration of the fast bombardment high field mass spectrometer and data system was accomplished using cesium iodide/glycerol as a reference. Mass calibration at --8 kV accelerating potential extends from m/z 387 to m/z 2170 using xenon fast atoms. Negative xenon FAB mass spectra for human angiotensin I and human gastrin I complement their positive fast atom bombardment spectra. Negative xenon fast atom bombardment spectra of underivatized peptides exhibit molecular proton-abstracted ion envelopes and structurally significant fragment ions. Peptide mixture analysis under negative xenon fast atom bombardment reveals peptide molecular ion envelopes of higher relative intensities than under positive xenon fast atom bombardment.