Antifungal activity of thionated analogues of Nva-FMDP and Lys-Nva-FMDP

The antifungal activity of synthetic endothiopeptdides, i.e. Nva(psi)[CSNH]-FMDP and Lys(psi)[CSNH]-Nva(psi)[CSNH]-FMDP was studied in medium containing blood serum, against selected Candida strains; Candida albicans Gu4 (fluconazole sensitive), C. albicans Gu5 (fluconazole resistant), C. albicans ATCC 10231, Candida krusei DSM 6128 and Candida parapsilosis DSM 5784. Although thiopeptide bonds in the tested peptides increased their stability in blood serum, their antifungal activity, however, drastically decreased in comparison with the peptides containing non-modified peptide bonds. Moreover, the inhibitory activity towards glucosamine-6-phosphate synthase of thionated synthetic analogue of FMDP was performed. The thiopeptdide bond also influenced its inhibitory properties against enzyme from C. albicans.

Purulent pericarditis caused by the Streptococcus milleri group: a case report and review of the literature

A 69-year-old woman with a history of diabetes mellitus presented at our emergency room with chest pain and dyspnea. A chest computed tomography revealed a pericardial effusion. Pericardiocentesis was performed; strains of the Streptococcus milleri group were detected on culture of the fluid thus obtained. Therefore, purulent pericarditis was diagnosed. Despite treatment with panipenem/betamipron, the pericarditis worsened leading to the development of cardiac tamponade. Emergency pericardial drainage was performed, after which the condition resolved without any complications. We report an extremely rare case of purulent pericarditis caused by a strain of the Streptococcus milleri group. In addition, we review 5 previously reported cases of purulent pericarditis caused by strains.

Determination of acrylamide during roasting of coffee

In this study different Arabica and Robusta coffee beans from different regions of the world were analyzed for acrylamide after roasting in a laboratory roaster. Due to the complex matrix and the comparably low selectivity of the LC-MS at m/ z 72, acrylamide was analyzed after derivatization with 2-mercaptobenzoic acid at m/ z 226. Additionally, the potential precursors of acrylamide (3-aminopropionamide, carbohydrates, and amino acids) were studied. The highest amounts of acrylamide formed in coffee were found during the first minutes of the roasting process [3800 ng/g in Robusta ( Coffea canephora robusta) and 500 ng/g in Arabica ( Coffea arabica)]. When the roasting time was increased, the concentration of acrylamide decreased. It was shown that especially the roasting time and temperature, species of coffee, and amount of precursors in raw material had an influence on acrylamide formation. Robusta coffee contained significantly larger amounts of acrylamide (mean = 708 ng/g) than Arabica coffee (mean = 374 ng/g). Asparagine is the limiting factor for acrylamide formation in coffee. 3-Aminopropionamide formation was observed in a dry model system with mixtures of asparagine with sugars (sucrose, glucose). Thermal decarboxylation and elimination of the alpha-amino group of asparagine at high temperatures (>220 degrees C) led to a measurable but low formation of acrylamide.

Identification and monitoring of intermediates and products in the acrylamide pathway using online analysis

Acrylamide formation under controlled processing conditions was studied in a starch matrix by analyzing volatile compounds in the gas phase using online mass spectrometry. Compounds were identified using mass spectral analysis, authentic standards, and the labeling patterns from isotopically labeled asparagine and sugars. Acrylamide, 3-aminopropanamide, methylpyrazine, 3-oxopropanamide, and aminopropan-2-one were assigned to the ions at m/ z 72, 89, 95, 88, and 74, respectively. Ion m/ z 60 was proposed as the transamination product of glyoxal, but labeling experiments did not support this assignment. Temporal formation of acrylamide and related compounds was studied in 51 samples containing asparagine and selected sugars or carbonyls. Data from the experiments were analyzed to investigate correlations between the amounts of acrylamide, intermediates, and pyrazines formed. A strong correlation between 3-aminopropanamide and acrylamide was found in all samples, whereas other correlations were reactant specific. Preliminary multiway analysis of the data identified temporal similarities in the ion profiles and showed that dynamic monitoring can follow the production and utilization of intermediates leading to acrylamide.

L-2,3-diaminopropionate: one of the building blocks for the biosynthesis of Zwittermicin A in Bacillus thuringiensis subsp. kurstaki strain YBT-1520

Zwittermicin A (ZwA) is a hybrid polyketide-non-ribosomal peptide that is thought to be biosynthesized from five proposed building blocks, including the 2,3-diaminopropionate. Candidate genes for de novo biosynthesis of 2,3-diaminopropionate, zwa5A and zwa5B, have been identified in a previous study. In this research, zwa5A was interrupted and chemically synthesized 2,3-diaminopropionate was used to feed the zwa5A(-) mutant. Results showed that feeding with 2,3-diaminopropionate restored the ability of the zwa5A(-) mutant to produce ZwA. Another non-ribosomal peptide synthase gene, designated orf3, was identified. Amino acid dependent PPi release assay showed that the adenylation domain ZWAA2 of ORF3 acyl-adenylated l-2,3-diaminopropionate effectively. Taken together, it can be concluded that l-2,3-diaminopropionate is indeed one of the building blocks for the biosynthesis of Zwittermicin A.

[Case of diabetes mellitus associated with cervical pyogenic spondylitis and meningoencephalitis secondary to retropharyngeal abscess caused by Streptococcus pneumoniae]

A 63-year-old man with diabetes mellitus had undergone insulin therapy for 10 years. He developed symptoms of upper respiratory tract infection and neck pain. After 5 days, he suddenly experienced high fever and consciousness disturbance. Neurological examination detected drowsiness and neck stiffness. Cerebrospinal fluid (CSF) examination revealed pleocytosis with low glucose level. Gram staining and a latex agglutination test of his CSF revealed Streptococcus pneumoniae to be the causative organism of meningoencephalitis in the patient. Gadolinium-enhanced T1-weighted images obtained from a cervical spine MRI showed ring enhancement in the anterior clivus and thickening in the anterior dura matter with specific thickening at the dens of the axis. Based on the diagnosis of cervical pyogenic spondylitis and meningoencephalitis secondary to retropharyngeal abscess caused by Streptococcus pneumoniae, the patient was administered panipenem/betamipron and dexamethasone, following which his neurological symptoms and signs gradually improved. Diabetes mellitus is a factor that predisposes patients to invasive pneumococcal infection. Thus, we conclude that physicians need to be aware of the possible development of cervical pyogenic spondylitis and meningoencephalitis subsequent to Streptococcus pneumoniae infection, and symptoms such as fever and neck pain should be carefully examined.

Solution structure of a novel D-naphthylalanine substituted peptide with potential antibacterial and antifungal activities

A new type of Trp-rich peptide, Ac-KWRRWVRWI-NH2, designated as Pac-525, was found to possess improved activity against both gram-positive and negative bacteria. We have synthesized two Pac-525 analogues, D-Pac-525 containing all D-amino acids and D-Nal-Pac-525, the D-Pac-525 analogue with tryptophan replaced by D-beta-naphthylalanine. We have determined the solution structure of D-Nal-Pac-525 bound to membrane-mimetic DPC micelles by two-dimensional NMR methods. The DPC micelle-bound structure of D-Nal-Pac-525 adopts a left-hand alpha-helical segment and the positively charged residues are clustered together to form a hydrophilic patch. The surface electrostatic potential map indicates the three D-beta-naphthylalanines are packed against the peptide backbone and form an amphipathic structure. A variety of biophysical and biochemical experiments, including circular dichroism, fluorescence spectroscopy, and microcalorimetry, were used to show that D-Nal-Pac-525 interacted strongly with negatively charged phospholipid vesicles and induced efficient dye release from these vesicles, suggesting that the strong antimicrobial activity of D-Nal-Pac-525 may be due to interactions with bacterial and fungus membranes.

Beta-ureidopropionase deficiency presenting with congenital anomalies of the urogenital and colorectal systems

Beta-ureidopropionase deficiency (McKusick 606673) is an autosomal recessive condition caused by mutations in the UPB1 gene. To date, five patients have been reported, including one putative case detected through newborn screening. Clinical presentation includes neurological and developmental problems. Here, we report another case of beta-ureidopropionase deficiency who presented with congenital anomalies of the urogenital and colorectal systems and with normal neurodevelopmental milestones. Analysis of a urine sample, because of the suspicion of renal stones on ultrasound, showed strongly elevated levels of the characteristic metabolites, N-carbamyl-beta-amino acids. Subsequent analysis of UPB1 identified a novel mutation 209 G>C (R70P) in exon 2 and a previously reported splice receptor mutation IVS1-2A>G. Expression studies of the R70P mutant enzyme showed that the mutant enzyme did not possess any residual activity. Long-term follow-up is required to determine the clinical significance of the beta-ureidopropionase deficiency in our patient.

Small molecule inhibitors of integrin alpha2beta1

Interactions between the integrin, alpha2beta1, and extracellular matrix (ECM), particularly collagen, play a pivotal role in platelet adhesion and thrombus formation. Platelets interact with collagen in the subendothelial matrix that is exposed by vascular damage. To evaluate the potential of alpha2beta1 inhibitors for anticancer and antithrombotic applications, we have developed a series of small molecule inhibitors of this integrin based on a prolyl-2,3-diaminopropionic acid (DAP) scaffold using solid-phase parallel synthesis. A benzenesulfonamide substituent at the N-terminus of the dipepetide and a benzyl urea at the DAP side chain resulted in tight and highly selective inhibition of alpha2beta1-mediated adhesion of human platelets and other cells to collagen.

Plasmepsin inhibitors: design, synthesis, inhibitory studies and crystal structure analysis

Plasmepsin group of enzymes are key enzymes in the life cycle of malarial parasites. As inhibition of plasmepsins leads to the parasite's death, these enzymes can be utilized as potential drug targets. Although many drugs are available, it has been observed that Plasmodium falciparum, the species that causes most of the malarial infections and subsequent death, has developed resistance against most of the drugs. Based on the cleavage sites of hemglobin, the substrate for plasmepsins, we have designed two compounds (p-nitrobenzoyl-leucine-beta-alanine and p-nitrobenzoyl-leucine-isonipecotic acid), synthesized them, solved their crystal structures and studied their inhibitory effect using experimental and theoretical (docking) methods. In this paper, we discuss the synthesis, crystal structures and inhibitory nature of these two compounds which have a potential to inhibit plasmepsins.

Phosphorylated FTY720 promotes astrocyte migration through sphingosine-1-phosphate receptors

Sphingosine-1-phosphate (S1P) receptors are widely expressed in the central nervous system where they are thought to regulate glia cell function. The phosphorylated version of fingolimod/FTY720 (FTY720P) is active on a broad spectrum of S1P receptors and the parent compound is currently in phase III clinical trials for the treatment of multiple sclerosis. Here, we aimed to identify which cell type(s) and S1P receptor(s) of the central nervous system are targeted by FTY720P. Using calcium imaging in mixed cultures from embryonic rat cortex we show that astrocytes are the major cell type responsive to FTY720P in this assay. In enriched astrocyte cultures, we detect expression of S1P1 and S1P3 receptors and demonstrate that FTY720P activates Gi protein-mediated signaling cascades. We also show that FTY720P as well as the S1P1-selective agonist SEW2871 stimulate astrocyte migration. The data indicate that FTY720P exerts its effects on astrocytes predominantly via the activation of S1P1 receptors, whereas S1P signals through both S1P1 and S1P3 receptors. We suggest that this distinct pharmacological profile of FTY720P, compared with S1P, could play a role in the therapeutic effects of FTY720 in multiple sclerosis.

Acute purulent meningitis associated with chronic subdural hematoma and subdural hygroma

A male infant aged nine months with meningeal irritation and +3.5SD expansion of the circumference of the head was admitted. Brain computed tomography (CT) detected right chronic subdural hematoma and contralateral subdural hygroma. Since the cell count was increased on a cerebrospinal fluid test, acute purulent meningitis was diagnosed. A rapid latex test and culture of cerebrospinal fluid identified Streptococcus pneumoniae (PSSP) as the pathogen. Panipenem/betamiprom (PAPM/BP) was administered at 100 mg/kg/3 times for 14 days and dexamethasone was administered at 0.6 mg/kg/4 times for 4 days, and the patient recovered without sequelae. Acute purulent meningitis complicated by chronic subdural hematoma and subdural hygroma is rare. In this case, acute subdural hygroma may have concomitantly developed with acute purulent meningitis in the presence of the chronic subdural hematoma, and rapid disequilibrium of intracranial pressure may have been the developmental mechanism.

Alternative pharmacokinetics of S-1 components, 5-fluorouracil, dihydrofluorouracil and alpha-fluoro-beta-alanine after oral administration of S-1 following total gastrectomy

We studied whether total gastrectomy for gastric cancer would affect the pharmacokinetics of 5-fluorouracil (5-FU) and its degradation products, such as dihydrouracil (FUH(2)) and alpha-fluoro-beta-alanine (FBAL), after oral administration of the fluorouracil derivative S-1, composed of tegafur, 5-chloro-2,4-dihydroxypyridine (CDHP; a dihydropyrimidine dehydrogenase inhibitor) and potassium oxonate. Blood and urine samples were obtained, both preoperatively and at least 2 weeks postoperatively, from six patients with advanced gastric cancers who were undergoing total gastrectomy. Plasma levels of tegafur, 5-FU, CDHP, potassium oxonate, FUH(2) and FBAL were measured prior to and at 1, 2, 4, 6 and 10 h after oral administration of 40 mg/m(2) S-1. The total amounts of 5-FU, FUH(2) and FBAL excreted into urine during the 24-h period after S-1 administration were also measured. Total gastrectomy significantly increased the maximum concentration and the area under the curve until 10 h after administration (AUC(1-10h)) of plasma 5-FU. The plasma AUC(1-10h) of CDHP was significantly higher than the preoperative value. In terms of clinical efficacy, the higher AUC(1-10h) of 5-FU after total gastrectomy may be beneficial to S-1 administered as adjuvant chemotherapy, and might be caused by the higher postoperative AUC(1-10h) of CDHP relative to preoperative values. However, the dose of S-1 for patients who have undergone total gastrectomy might be diminished to avoid severe adverse events and to continue the treatment for a long period.

Discovery and partial characterization of primate motor-system toxins

beta-N-Oxalylamino-L-alanine (BOAA) and beta-N-methylamino-L-alanine (BMAA) are chemically related excitant amino acids isolated from the seed of Lathyrus sativus (BOAA) and Cycas circinalis (BMAA), consumption of which has been linked to lathyrism (an upper motor neuron disorder) and Guam amyotrophic lateral sclerosis (ALS), respectively. Both diseases are associated with degeneration of motor neurons. Experimentally, single doses of BOAA or BMAA induce seizures in neonatal mice and postsynaptic neuronal oedema and degeneration in explants of mouse spinal cord and frontal cortex. Preliminary studies show that these behavioural and pathological effects are differentially blocked by glutamate-receptor antagonists. In macaques, several weeks of daily oral doses of BOAA produce clinical and electrophysiological signs of corticospinal dysfunction identical to those seen in comparably well-nourished animals receiving a fortified diet based on seed of Lathyrus sativus. By contrast, comparable oral dosing with BMAA precipitates tremor and weakness, bradykinesia and behavioural changes, with conduction deficits in the principal motor pathway. BOAA and BMAA (or a metabolite thereof) are the first members of the excitotoxin family to have been shown to possess chronic motor-system toxic potential. These observations provide a rational basis for searching for comparable endogenous neurotoxins in sporadic and inherited forms of human motor neuron disease.

Chiroptical properties of diamino carboxylic acids

Diamino carboxylic acids have recently come to the attention of scientists working in the field of early life and its development. These are the monomers of a hypothetic early form of genetic material, the so-called Peptide Nucleic Acid (PNA) (Nielson et al., Proc Natl Acad Sci USA 2000;97:3868-3871). Since all biopolymers rely on a specific handedness of their building blocks, the question of symmetry breaking occurs in diamino acids and PNA in the same way as in amino acids and proteins. One possible mechanism for triggering this, is asymmetric photochemistry in interstellar/circumstellar matter by means of circularly polarized light (Bailey et al., Science 2005;281:672-674; Bailey, Orig Life Evol Biosphere 2001;21:167-183; Buschermöhle, Astrophys J 2005;624:821-826; Meierhenrich, Angew Chem Int Ed Engl 2005;44:5630-5634). Here we have measured the CD-spectra of four chiral diamino carboxylic acids, three of which were found in the Murchison meteorite (Meierhenrich, Proc Natl Acad Sci USA 2004;101:9182-9186). The spectra show a uniform peak at 200 nm. These results and additional quantum mechanical calculations of the involved molecular orbitals support the assumption that the process of symmetry breaking in diamino acids does not depend significantly on the length of the side chain. This means that one process alone could suffice to lead to symmetry breaking in all four measured diamino carboxylic acids and might even to some extent be transferable to monoamino acids, the monomers of proteins.

Radiolabeled high affinity peptidomimetic antagonist selectively targets alpha(v)beta(3) receptor-positive tumor in mice

OBJECTIVES

The aim of this research was to synthesize radiolabeled peptidomimetic integrin alpha(v)beta(3) antagonists that selectively target integrin alpha(v)beta(3) receptor and clear rapidly from the whole body.

METHODS

Integrin alpha(v)beta(3) antagonists, 4-[2-(3,4,5,6-tetrahydropyrimidine-2-ylamino)ethyloxy]benzoyl-2-(S)-aminoethylsulfonyl-amino-beta-alanine (IA) and 4-[2-(3,4,5,6-tetrahydro-pyrimidin-2-ylamino)-ethyloxy]benzoyl-2-(S)-[N-(3-amino-neopenta-1-carbamyl)]-aminoethylsulfonylamino-beta-alanine hydrochloride (IAC), a hydrophobic carbamate derivative of IA, were conjugated with 2-p-isothiocyanatobenzyl-DOTA at the amino terminus and labeled with (111)In. The (111)In labeled IA and IAC were subjected to in vitro receptor binding, biodistribution and imaging studies using nude mice bearing the receptor-positive M21 human melanoma xenografts.

RESULTS

The (111)In-labeled IA (40%) and -IAC (72%) specifically bound in vitro to alpha(v)beta(3) (0.8 microM) at a molar excess. This receptor binding was completely blocked by a molar excess of cold IA to alpha(v)beta(3). The higher receptor-binding affinity of the (111)In-labeled IAC was reflected in higher tumor uptake and retention: 5.6+/-1.4 and 4.5+/-0.7 %ID/g vs. 3.8+/-0.9 and 2.0+/-0.3 %ID/g for the (111)In-labeled IA at 0.33 and 2 h. The tumor uptakes were inhibited by the co-injection of 200 microg of IA, indicating that the uptake was receptor mediated. These antagonists were excreted primarily via the renal system. The (111)In activity retained in the whole body was quite comparable between the (111)In-labeled IA (24% ID) and the (111)In-labeled IAC (33% ID) at 2 h. The higher peak tumor uptake and longer retention resulted in higher tumor-to-background ratios for the (111)In-labeled IAC at 2 h with 9.7, 2.3, 0.8, 1.9, 7.1, 2.2, 0.9, 3.7 and 9.9 for blood, liver, kidney, lung, heart, stomach, intestine, bone and muscle, respectively. The imaging studies with the (111)In-labeled IAC also clearly visualized the receptor-positive tumor at 4 h.

CONCLUSIONS

The (111)In-labeled IAC showed an improve tumor targeting kinetics with rapid accumulation and prolonged retention in the alpha(v)beta(3) receptor-positive tumor. This together with the rapid whole-body clearance pharmacokinetics warrants further studies on this IAC analog for molecular imaging of tumor-induced angiogenic vessels and various malignant human tumors expressing the receptor.

Synthesis of β-alanine C60 derivative and its protective effect on hydrogen peroxide-induced apoptosis in rat pheochromocytoma cells

Oxidative stress has been considered as a major cause of cellular injuries in a variety of clinical abnormalities, especially prominent in neural diseases. One of the effective ways to prevent the reactive oxygen species (ROS) mediated cellular injury is dietary or pharmaceutical augmentation of some free radical scavenger. Water-soluble amino-fullerene derivative is a novel compound that behaves as a free radical scavenger with excellent biocompatibility. In the present study, we synthesized a novel beta-alanine C(60) derivative. The product was characterized by FT-IR, (1)H NMR, (13)C NMR, LC-MS and elemental analysis. We investigated the protective effect on hydrogen peroxide-induced oxidative stress and apoptotic death in cultured rat pheochromocytoma (PC12) cells. PC12 cells treated with hydrogen peroxide underwent apoptotic death determined by MTT, flow cytometry analysis and PI/Hoechst 33342 staining. Moreover, the scavenging ability of beta-alanine C(60) derivative to reactive oxygen species both in vivo and in vitro of PC12 cells was measured. The results suggest that beta-alanine C(60) derivative has the potential to prevent oxidative stress-induced cell death without evident toxicity. Hence, on the basis of the above-mentioned studies, we can hypothesize that the protective effect of beta-alanine C(60) derivative on H(2)O(2) induced apoptosis is related to their known scavenger activity toward ROS.

Variable stability heterodimeric coiled-coils from manipulation of electrostatic interface residue chain length

The design of variable-stability coiled-coil heterodimers is described. The electrostatic interface between helices, formed by contact between side chains in heptad e/g positions, is manipulated to produce complexes ranging in stability from ones that are essentially unstructured to those that cannot be thermally denatured. The tuning is accomplished by incremental extension or contraction of parent glutamic acid and lysine side chains by single methylene units, producing peptides that bear either carboxylic acids or amines separated from the peptide backbone by one to four CH2 groups. Detailed examination of all homodimers and electrostatically compatible heterodimers generates interesting combinations, particularly those in which longer-chain acids are incorporated into peptides paired with lysine-bearing ones. The discovery of very stable dimers allows exchange experiments in which one strand of an original heterodimer is specifically replaced by an added one, even in cases where the original complex features the native-like glutamic acid/lysine pairing. The reported results add significantly to the available design templates for coiled-coil construction and enable the future implementation of various triggered-recognition strategies.

A reassessment of the function of the so-called compatible solutes in the halophytic plumbaginaceae Limonium latifolium

The compatible solute hypothesis posits that maintaining osmotic equilibrium under conditions of high salinity requires synthesis of organic compounds, uptake of potassium ions, and partial exclusion of NaCl. To assess whether osmotic adaptation in Limonium latifolium proceeds according to this hypothesis, a comprehensive analysis of solute accumulation during NaCl treatments was conducted. Determination of prevailing inorganic ions and establishment of the metabolic profiles for low M(r) organic substances revealed that contrary to the mentioned hypothesis the major contributors to osmolarity were constituted by inorganic solutes. Independent of salinity, only 25% of this osmolarity resulted from organic solutes such as Suc and hexoses. Proline (Pro), beta-alanine betaine, and choline-O-sulfate were minor contributors to osmolarity. Compatible inositols also occurred, especially chiro-inositol, characterized for the first time in this species, to our knowledge. Principal component analysis showed that only a limited number of metabolic reconfigurations occurred in response to dynamic changes in salinity. Under such conditions only sugars, chiro-inositol, and Pro behave as active osmobalancers. Analysis of metabolic profiles during acclimatization to either mild salinity or nonsaline conditions showed that organic solute accumulation is predominantly controlled by constitutive developmental programs, some of which might be slightly modulated by salinity. Osmolarity provided under such conditions can be sufficient to maintain turgor in salinized seedlings. Compartmental analysis of Pro and beta-alanine betaine in leaf tissues demonstrated that these solutes, mainly located in vacuoles under nonsaline conditions, could be partly directed to the cytosol in response to salinization. Thus they did not conform with the predictions of the compatible solute hypothesis.

From tyrosine to glycine: synthesis and biological activity of potent antagonists of the purinergic P2X7 receptor

The characterization of the native and recombinant P2X7 receptor continues to be hindered by the lack of specific and subtype-selective antagonists with a "druglike" profile. However, a tyrosine derivative named KN-62 exhibits selective P2X7 receptor-blocking properties. As a molecular simplification of KN-62, the present study was designed to evaluate the functional antagonistic properties of a novel series of glycine derivatives characterized by the presence of different phenyl-substituted piperazine moieties. Antagonistic activity of these glycine derivatives was tested on HEK293 cells transfected with the human P2X7 receptor. The most potent P2X7 receptor antagonist identified in this study (compound 4g) contains an o-fluorine substituent on the phenylpiperazine moiety and had an IC50 of 12.1 nM. The biological responses investigated were ATP-dependent Ca2+ influx across the plasma membrane and ethidium bromide uptake.

Influence of sulfur fertilization on the amounts of free amino acids in wheat. correlation with baking properties as well as with 3-aminopropionamide and acrylamide generation during baking

Sulfur (S) fertilization has been long-known to influence the amounts of total free amino acids in plants. To determine the impact of S deficiency in wheat on the concentration of, in particular, free asparagine, the spring wheat cultivar 'Star' was grown in a laboratory scale (5 L pot) at five different levels of S fertilization. After maturity, the kernels were milled into white flours (1-5) and analyzed for their contents of total S and total nitrogen as well as for free amino acids and glucose, fructose, maltose, and sucrose. Extremely high concentrations of free asparagine (Asn; 3.9-5.7 g/kg) were determined in flours 1 and 2 (30 and 60 mg of S), whereas much lower amounts (0.03-0.4 g/kg) were present in flours grown at higher S levels. The amounts of the reducing carbohydrates were, however, scarcely affected by S fertilization. In agreement with the high amount of Asn in flours 1 and 2, heating of both flours led to the generation of very high amounts of acrylamide (1.7-3.1 mg/kg) as well as of 3-aminopropionamide (40-76 mg/kg). Similar concentrations were measured in crispbread prepared from both flours. Application of rheological measurements on doughs prepared from each flour and a determination of the loaf volume of bread baked therefrom clearly indicated that flours 1 and 2 would be excluded from commercial bread processing due to their poor technological properties. Two commercial flours showed relatively low concentrations of acrylamide after a thermal treatment.

Acidosis-sensing glutamine pump SNAT2 determines amino acid levels and mammalian target of rapamycin signalling to protein synthesis in L6 muscle cells

Wasting of lean tissue as a consequence of metabolic acidosis is a serious problem in patients with chronic renal failure. A possible contributor is inhibition by low pH of the System A (SNAT2) transporter, which carries the amino acid L-glutamine (L-Gln) into muscle cells. The aim of this study was to determine the effect of selective SNAT2 inhibition on intracellular amino acid profiles and amino acid-dependent signaling through mammalian target of rapamycin in L6 skeletal muscle cells. Inhibition of SNAT2 with the selective competitive substrate methylaminoisobutyrate, metabolic acidosis (pH 7.1), or silencing SNAT2 expression with small interfering RNA all depleted intracellular L-Gln. SNAT2 inhibition also indirectly depleted other amino acids whose intracellular concentrations are maintained by the L-Gln gradient across the plasma membrane, notably the anabolic amino acid L-leucine. Consequently, SNAT2 inhibition strongly impaired signaling through mammalian target of rapamycin to ribosomal protein S6 kinase, ribosomal protein S6, and 4E-BP1, leading to impairment of protein synthesis comparable with that induced by rapamycin. It is concluded that even though SNAT2 is only one of several L-Gln transporters in muscle, it may determine intracellular anabolic amino acid levels, regulating the amino acid signaling that affects protein mass, nucleotide/nucleic acid metabolism, and cell growth.

Use of antibody as carrier of oligomers of peptidomimetic alphavbeta3 antagonist to target tumor-induced neovasculature

Sulfhydryl selective reactions were explored to conjugate oligomers of a peptidomimetic integrin alphavbeta3 antagonist, 4-[2-(3,4,5,6-tetrahydropyrimidine-2-ylamino)ethyloxy]benzoyl-2-(S)-aminoethylsulfonylamino-beta-alanine (IA) to monoclonal antibody (MoAb) to increase integrin alphavbeta3 receptor-binding avidity. To generate sulfhydryl groups, N-succinimidyl-S-acetylthioacetate (SATA) was conjugated to both MoAb and IA. Sulfhydryl groups were then generated upon the deacetylation of the protecting acetyl group from the S-acetylthioacetato (ATA) moiety of MoAb-(ATA)n or IA-ATA with 0.02 M hydroxylamine in the presence of 1 mM EDTA at pH 7.2. The major focus was on optimizing the reaction concentrations, molar ratios, and reaction pH to conjugate high levels of IA-(A-SH) to MoAb-(A-SH)n without causing the inter- and intramolecular cross-linking of MoAb. Stepwise reactions of MoAb-(A-SH)n (15 microM MoAb) with a homobifunctional cross-linker, 1,8-bis(maleimido)diethylene glycol (BM[PEO]2) at a >50x molar excess to the -SH, followed by the reaction of the purified product MoAb-(A-S-succinimidomaleimido-[PEO]2)n with IA-(A-SH) at pH 7.2 afforded monomeric MoAb-(A-S-succinimido-[PEO]2-succinimido-S-A-IA)n with <10% high molecular weight oligomeric MoAb. Monomeric MoAb-(A-S-S-[PEO]2-S-S-A-IA)10 (MoAb-IA10) radiolabeled with 111In using 2-(p-isothiocyanatobenzyl)cyclohexyl-DTPA and with 125I using the Iodogen method showed >70% bindability to 0.4 microM alphavbeta3. When injected iv to nude mice with the receptor-positive M21 tumor, MoAb-IA10 radiolabeled with both 111In and 125I accumulated rapidly and was retained in the tumor for a 44 h period while the radioactivity cleared rapidly from the blood, thereby resulting in increasing tumor-to-blood ratios over time. The tumor uptake was similar between the 125I label and the 111In label for a 44 h period. In contrast, the blood radioactivity was lower, but liver and other organ uptakes were much higher for the 111In label than for the 125I. The 111In label produced higher tumor-to-blood ratios but much lower tumor-to-organ ratios than the 125I. The rapid blood clearance, a short peak tumor uptake time, and a low peak tumor uptake value with prolonged tumor retention of this macromolecule appear to support a hypothesis that MoAb-IA10 primarily binds to alphavbeta3 receptors on angiogenic vessels, but not on the tumor. This hypothesis was substantiated by the fluorescence microscopic analysis of FITC-MoAb-IA10, which showed that FITC-MoAb-IA10 outlined neovasculatures but not tumor cells at 4 and 21 h ex vivo. Additional proof was observed when blood vessels outlined with rhodamine-lectin, which specifically binds to blood vessels, were superimposable on neovasculatures outlined with FITC-MoAb-IA10.

New beta-alanine derivatives are orally available glucagon receptor antagonists

A weak human glucagon receptor antagonist with an IC50 of 7 microM was initially found by screening of libraries originally targeted to mimic the binding of the glucagon-like peptide (GLP-1) hormone to its receptor. Optimization of this hit for binding affinity for the glucagon receptor led to ligands with affinity in the nanomolar range. In addition to receptor binding, optimization efforts were made to stabilize the molecules against fast metabolic turnover. A potent antagonist of the human human glucagon receptor was obtained that had 17% oral availability in rats with a plasma half-life of 90 min. The major metabolites of this lead were identified and used to further optimize this series with respect to pharmacokinetic properties. This final optimization led to a potent glucagon antagonist that was orally available in rats and dogs and was efficacious in lowering blood glucose levels in a diabetic animal model.