Syntheses and biological properties of new 8-fluorocarbapenem derivatives

8-Fluorocarbapenem derivatives having various C-3 side chains were synthesized to study for the structure-activity relationship of carbapenems by in vitro biological evaluation. The introduction of fluorine at C-8 of racemic PS-5 led to slight improvements of the antimicrobial activity and the stability to renal dehydropeptidase-I. When D-cysteine was additionally introduced to the C-3 position of (+/-)-8-fluorocarbapenem, the diastereomeric separation of the 8-fluorocarbapenems became feasible. As expected from penicillins and cephalosporins, (+)-8-fluoro-3-D-cysteinylcarbapenem (+)-7a was antimicrobially active, whereas (-)-7b was inactive. It is worth noting, however, that (+)-7a was significantly more sensitive to renal dehydropeptidase-I than (-)-7b. Irrespective of the presence of fluorine at C-8, basic S-side chains at C-3, such as the pyridyl and pyrrolidyl groups, significantly improved in antimicrobial activity and dehydropeptidase-I stability. The combination of 8-fluorination with C-3 basic side chains in 7c--g resulted in a marked improvement of antimicrobial activity and dehydropeptidase-I stability.     

Carbon-13 Separation by IRMPD of mixtures of C2F6 and Br2

The infrared multiple-photon decomposition of mixtures of C₂F₆ and Br₂ has been examined as functions of various experimental parameters. Carbon-13 was found to be enriched in the main product CF₃Br; the maximum enrichment factor was 35. The combination of this process with the IRMPD of CF₃Br provides a closed chemical cycle for efficient carbon isotope separation     

Serum ferritin in patients with malignant neoplasms

Serum ferritin levels were studied in 264 patients who were consisted of 153 patients with various malignant neoplasms and 111 patients with various benign diseases. Positive rate of serum ferritin in all patients with malignant neoplasms was 35%. Hepatomas and pulmonary cancer showed relatively high positive rate, respectively 65% and 42%. In patients with benign diseases, hepatic diseases showed the high positive rate (52%) and the other benign diseases was low positive rate (11%). The relationship between serum ferritin and alpha-feto-protein in patients with hepatomas and other liver diseases was low. And the relationship between serum ferritin and CEA (carcinoembryonic antigen) in patients with malignant neoplasms of gastrointestinal tract was also low. It seemed that the measurement of serum ferritin levels will be of low value in the differentiation of the patients with malignant neoplasms.     

Uptake of Au(III) Ions by Aluminum Hydroxide and Their Spontaneous Reduction to Elemental Gold (Au(0))

The behavior of AuCl(4)(-) ions during the formation of aluminum hydroxide at pH 6 was examined. With an increase in NaCl concentration, the content of gold taken up by aluminum hydroxide decreased, suggesting that chloro-hydroxy complexes of Au(III) ion were taken up due to the formation of Al-O-Au bonds. It was found unexpectedly that the Au(III) ions taken up were spontaneously reduced to elemental gold without addition of a specific reducing reagent and then colloidal gold particles were formed. The mechanisms for the uptake of Au(III) ions by aluminum hydroxide and for their spontaneous reduction are discussed. Copyright 2001 Academic Press.     

Spectrophotometric determination of manganese with 1-(2-pyridylazo)-2-naphthol and a non-ionic surfactant

A spectrophotometric method for the determination of trace amounts of manganese with 1-(2-pyridylazo)-2-naphthol (PAN) is described. The method is based on the measurement of absorbance of the manganese—PAN chelate solubilized with a non-ionic surfactant, Triton X-100. No extraction procedure is required in the method proposed. High concentrations of calcium, aluminium and magnesium do not interfere. The presence of up to 10 ppm of lead can be tolerated. Iron, cadmium, zinc, cobalt and nickel can be effectively masked with potassium cyanide. Beer's law is obeyed up to 2 ppm of manganese. The molar absorptivity of the manganese—PAN chelate found was 4.4 × 10⁴ l. mole ⁻¹. cm⁻¹ at 562 nm. The overall stability constant of Mn(PAN)₂ in 0.4% Triton X-100 medium is 10^16.8.     

Synthesis and characterization of stereoregular poly(methyl methacrylate)–silica hybrid utilizing stereocomplex formation

Stereoregular poly(methyl methacrylate) (PMMA)–silica nanocomposites were prepared using stereocomplex formation between i-PMMA and s-PMMA by an in situ method. The methodology adopted here is the simultaneous formation of organic gel and inorganic gel, the so-called interpenetrating polymer network (IPN) formation. The gelation of i- and s-PMMA were performed by stereocomplex formation with the associated segments forming the crosslinking points in the presence of tetramethoxysilane (TMOS). The effects of the i/s-ratio, PMMA concentration, molecular weight, and solvent nature on the hybrid materials formation were addressed. The presence of the stereocomplex in the silica matrix was confirmed by DSC and solvent extraction methods. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 785–794, 2004     

Sterilization of Bacillus spores by converted X rays

Relative sensitivities of endospores of Bacillus pumilus E601, B. subtilis IAM1069, B. megaterium S31 and B. brevis S5 to gamma rays, converted X rays (bremsstrahlung) and electron beams were examined in order to estimate the conditions in which converted X rays kill Bacillus spores. The radiation sensitivities to gamma rays and electron beams of each strain dried on glass fiber filter without additives were found to be almost equivalent, and D values were obtained as follows: 1.5–1.6 kGy for B. pumilus, 1.4–1.5 kGy for B. subtilis, 1.9–2.0 kGy for B. megaterium and 1.6–2.0 kGy for B. brevis. The radiation sensitivities of endospores of each strain to electron beams were slightly lower than those to gamma rays in the dry condition with additives of 2% peptone + 1 % glycerin on glass fiber filters. The increase of radiation resistance in the presence of additives was also observed with X rays, and it was on an intermediate level between those with gamma rays and electron beams. In the dry condition using cellulose filter paper, only the radiation resistances of B. megaterium and B. brevis in the presence of additives B. megaterium and B. brevis in the presence of additives were increased.     

EFFECT OF PHOSPHATE ION ON FLUORESCENT CHARACTERISTICS OF TYROSINE AND ITS CONJUGATE BASE

Abstract—The UV fluorescence spectrum of tyrosine (Tyr) is markedly affected by the interaction with phosphate ion. In order to elucidate the mechanism of the specific fluorescence quenching by phosphate and the simultaneous appearance of a new emission, the effect of phosphate on the spectro-scopic characteristics of Tyr was investigated. Employing a fluorimetric method, we have obtained the following results. Namely, potassium phosphate was found to enhance the fluorescence intensity of tyrosinate ion. When Tyr is excited in the phosphate-containing solution, the emission with a peak around 345 nm is observed besides the normal fluorescence of Tyr around 303 nm with a reduced quantum yield. The abnormal emission may be ascribed to the tyrosinate ion in the excited state resulting from the deprotonation of the phenolic OH group of the excited Tyr. although the tyrosinate ion in the ground state is not predominant in the aqueous solution examined.     

Double-modification of lectin using two distinct chemistries for fluorescent ratiometric sensing and imaging saccharides in test tube or in cell

The site-selective incorporation of two different fluorophores into a naturally occurring protein (lectin, a sugar-binding protein) has been successfully carried out using two distinct orthogonal chemical methods. By post-photoaffinity labeling modification, Con A, a glucose- and mannose-selective lectin, was modified with fluorescein in the proximity of the sugar binding site (Tyr100 site), and the controlled acylation reaction provided the site-selective attachment of coumarin at Lys114. In this doubly modified Con A, the fluorescein emission changed upon the binding to the corresponding sugars, such as the glucose or mannose derivatives, whereas the coumarin emission was constant. Thus, the doubly modified Con A fluorescently sensed the glucose- and mannose-rich saccharides in a ratiometric manner while retaining the natural binding selectivity and affinity, regardless of the double modification. On the benefit of the ratiometric fluorescent analysis using two distinct probes, the sugar trimming process of a glycoprotein can be precisely monitored by the engineered Con A. Furthermore, the doubly modified Con A can be used not only for the convenient fluorescent imaging of saccharides localized on a cell surface, such as the MCF-7, a breast cancer cell having rich high-mannose branch, but also for the ratiometric fluorescent sensing of the glucose concentration inside HepG2 cells. These results demonstrated that the semisynthetic lectin modified doubly by two distinct chemistries is superior to the singly modified one in function, and thus, it may be potentially useful in cell, as well as in test tube.     

Facile formation of chiral calixarene analogs incorporating cystine peptide into the macrocyclic ring

Chiral calixarene analogs incorporating cystine peptide into their macrocyclic ring were easily prepared by the cyclization reactions of bis(chloromethyl)phenol-formaldehyde oligomers with cystine peptides in moderate yields. Circular dichroism (CD) spectra indicated the existence of the transmission of the chirality from peptide unit to phenol-formaldehyde oligomer moiety.