New obligate methylotroph

A new and unique obligate methylotroph was isolated from enrichment cultures with methanol as the sole source of carbon and energy. The organism grows only on methanol and methylamine and not on methane. It does not have a complex intracellular membrane system. (14)C-acetate was assimilated by growing cultures and cell suspensions but was incorporated into only a limited number of cell constituents. (14)C-acetate incorporation was strictly dependent on the oxidation of methanol or methylamine as a source of energy. Extracts had relatively low levels of enzymes of the tricarboxylic acid cycle, and alpha-ketoglutarate dehydrogenase was not detected. Comparisons were made with a facultative methylotroph isolated from the same enrichment cultures. The new obligate methylotroph contained hexose phosphate synthetase, a key enzyme in the ribose phosphate cycle of methyl metabolism.

Transmembrane-truncated alphavbeta3 integrin retains high affinity for ligand binding: evidence for an 'inside-out' suppressor?

The molecular mechanisms of alphavbeta3 integrin affinity regulation have important biological implications in tumour development, wound repair and angiogenesis. We expressed, purified and characterized recombinant forms of human alphavbeta3 (r-alphavbeta3) and compared the activation state of these with alphavbeta3 in its cellular environment. The ligand specificity and selectivity of recombinant full-length and double transmembrane truncations of r-alphavbeta3 cloned in BacPAK6 vectors and expressed in Sf9 and High Five insect cells were compared with those of native placental alphavbeta3 and the receptor in situ on the cell surface. r-alphavbeta3 integrins were purified by affinity chromatography from detergent extracts of cells (full-length), and from the culture medium of cells expressing double-truncated r-alphavbeta3. r-alphavbeta3 had the same epitopes, ligand-binding specificities, bivalent cation requirements and susceptibility to RGD-containing peptides as native alphavbeta3. On M21-L4 melanoma cells, alphavbeta3 mediated binding to vitronectin, but not to fibrinogen unless activated with Mn2+. Non-activated alphaIIbbeta3 integrin as control in M21-L-IIb cells had the opposite profile, mediating binding to fibrinogen, but not to vitronectin unless activated with Mn2+. Thus these receptors had moderate to low ligand affinity. In marked contrast, purified alphavbeta3 receptors, with or without transmembrane and cytoplasmic domains, were constitutively of high affinity and able to bind strongly to vitronectin, fibronectin and fibrinogen under physiological conditions. Our data suggest that, in contrast with the positive regulation of alphaIIbbeta3 in situ, intracellular controls lower the affinity of alphavbeta3, and the cytoplasmic domains may act as a target for negative regulators of alphavbeta3 activity.

A novel peptide delivery system involving peptidase activated prodrugs as antimicrobial agents. Synthesis and biological activity of peptidyl derivatives of 5-fluorouracil

As an approach to the development of antimicrobial agents, a novel peptide carrier system was designed, based on the chemical instability of alpha-substituted glycine analogues, with the explicit intent of actively transporting therapeutically useful compounds into microbial cells. Peptides containing 5-fluorouracil (5-FU) linked to the peptide backbone were selected to test the feasibility of this new delivery system. These peptide conjugates were designed such that they would be substrates for both the microbial peptide permeases and peptidases. After entry into cells, enzymatic hydrolysis of the peptide generates an unstable alpha-(5-FU)-glycine that spontaneously decomposes to release 5-FU. The 5-FU-peptide conjugates were tested for antifungal (Candida albicans) and antibacterial (Escherichia coli) activity and were found to have antimicrobial activities comparable to free 5-FU. Noninhibitory peptides antagonized the antimicrobial activities of the 5-FU-peptide conjugates but not of free 5-FU, a result consistent with peptide transport mediated entry of the peptide conjugates into cells. Further support for this conclusion was provided by the finding that biological activities were dependent upon peptide stereochemistry.

Extrathoracic metastases of thymic origin: a review of 35 cases

Thymic tumors are categorized as types A, AB, B1, B2, B3, and thymic carcinoma under the World Health Organization (WHO) classification. Thymomas are typically slow growing tumors that predominantly involve the surrounding structures through direct invasion, while thymic carcinomas tend to be more aggressive. A significant number of patients are asymptomatic and can present with metastases as the first presentation. The exact incidence of extrathoracic metastases from thymoma is not known. This study describes a series of 35 cases of histologically documented metastatic thymomas and thymic carcinomas at extrathoracic sites. These cases were classified according to the current World Health Organization (WHO) classification criteria, and we present their clinical data as well as discuss the differential diagnoses of these lesions. Our study shows that all types of thymic tumors, regardless of histologic type, can be associated with invasion and metastases to thoracic and extrathoracic sites.

Transport of antimicrobial agents using peptide carrier systems: anticandidal activity of m-fluorophenylalanine--peptide conjugates

A series of di- and tripeptides containing D- and L-m-fluorophenylalanine was prepared and tested in vitro for the ability to inhibit the growth of the yeast Candida albicans. The results demonstrate that peptides containing L-m-fluorophenylalanine inhibited the growth of C. albicans with minimum inhibitory concentrations (MIC's) ranging from 0.5 to 63 micrograms/mL. The parent L-m-fluorophenylalanine and peptides containing D-m-fluorophenylalanine were inactive (MIC greater than 250 micrograms/mL) in these tests. The results of competitive antagonism studies support peptide transport mediated entry of the inhibitory peptides, followed by release of L-m-fluorophenylalanine inside the cell.

Glycopeptide antibiotics: a mechanism-based screen employing a bacterial cell wall receptor mimetic

The evolution of a highly targeted screening program for the discovery of antibiotics of the glycopeptide (vancomycin) class is described. A holistic approach was utilized which optimized not just screening techniques but also the selection of candidate producer cultures and their growth under conditions which enhanced production of target compounds. Two screen techniques were utilized; differential inhibition of a vancomycin-resistant strain and its susceptible parent, and a specific antagonism screen using the reversal of glycopeptide activity by a tripeptide analog of the glycopeptide receptor, diacetyl-L-lysyl-D-alanyl-D-alanine. The latter screen was 2- to 32-fold more sensitive to known glycopeptides than the former, and was absolutely specific, yielding no false positive responses. The use of the tripeptide antagonism assay, combined with optimized culture selection and growth conditions yielded novel glycopeptide antibiotics at a rate of 1 per 320 cultures screened. With a holistic approach to screening and properly optimized techniques, large numbers of cultures do not need to be examined in order to discover novel antibiotics.

Anti-Candida activity of polyoxin: example of peptide transport in yeasts

The polyoxins, nucleoside peptide antibiotics, are effective inhibitors of chitin synthesis in some fungi and yeasts. Although isolated chitin synthetases appear to be equally sensitive to inhibition by polyoxins, intact yeast cells are relatively insensitive. It has been suggested that polyoxins enter cells by a peptide carrier transport mechanism. In this paper, we report results which demonstrate that changes in the growth conditions significantly affect the degree of sensitivity of Canidida albicans to the polyoxins. For example, a minimal inhibitory concentration of 0.1 micrograms/ml was obtained in a defined medium compared with a minimal inhibitory concentration of 1,000 micrograms/ml with conventional media. Various noninhibitory di- and tripeptides, when added to the media, were found to antagonize the anti-Candida activity of polyoxins. In addition, polyoxin-resistant mutants of C. albicans were shown to exhibit cross-resistance with other dipeptide antibiotics. The data reported herein support peptide transport of polyoxins in C. albicans.

Kibdelins, novel glycopeptide antibiotics. I. Discovery, production, and biological evaluation

A new subspecies of Kibdelosporangium aridum subsp. largum (SK&F AAD-609), was isolated and shown to produce novel glycopeptides related to aridicins, but containing a homologous series of glycolipids based on N-acylglucosamine. These compounds showed improvements over the aridicins in in vitro activity and were effective in mouse protection studies against a range of Gram-positive bacteria, including methicillin resistant staphylococci. Pharmacokinetic studies indicated that they have high serum concentrations and long-acting potential. The kibdelin complex modified rumen metabolism in a manner favorable for growth promotion.

The effect of aculeacin A and papulacandin B on morphology and cell wall ultrastructure in Candida albicans

Transmission (TEM) and scanning electron microscopy (SEM) of Candida albicans cultures treated with the cell wall active antibiotics aculeacin A and papulacandin B (10 micrograms/mL) revealed highly distorted, wrinkled, and collapsed cells. Dividing cells failed to separate properly and aggregates of enlarged and elongated forms were often seen. TEM sections revealed thick and layered cell walls in the treated cultures and bud cross walls failed to segregate completely. Approximately 20% of the cells demonstrated complete cell necrosis accompanied with cytoplasmic deterioration, layered and distorted walls, and improperly formed buds and scars.

Chlorocardicin, a monocyclic beta-lactam from a Streptomyces sp. I. Discovery, production and biological activities

Chlorocardicin is a new monocyclic beta-lactam produced by a Streptomyces sp. It is structurally related to nocardicin A but differs in having a m-chloro substituent on the p-hydroxyphenylglycine unit. The biological activity of chlorocardicin was similar to nocardicin A but the former showed less antagonism in complex media. Moderate in vitro activity was observed against Enterobacteriaceae and Pseudomonas aeruginosa. Chlorocardicin showed low activity against Staphylococcus aureus whereas nocardicin A was inactive. Both compounds were shown to be strongly potentiated by antibiotics that inhibit peptidoglycan biosynthesis and were antagonized by selected L- and D-amino acids.

Actinoidin A2, a novel glycopeptide: production, preparative HPLC separation and characterization

An unidentified Nocardia sp. (SK&F-AAJ-193) was isolated and found to produce actinoidin A and a novel analog which we have named actinoidin A2. This new glycopeptide antibiotic differs from actinoidin A by the presence of rhamnose instead of acosamine. This analog was isolated using Dianion HP-20 resin followed by a specific glycopeptide affinity column (Affigel-10-D-Ala-D-Ala). The purification was accomplished using preparative ion-pairing chromatography. Actinoidin A2 is active against Staphylococcus aureus and coagulase-negative Staphylococci although it is less potent than actinoidin A.

Chemotherapy Versus Chemotherapy Plus Chemoradiation as Neoadjuvant Therapy for Resectable Gastric Adenocarcinoma: A Multi-institutional Analysis

OBJECTIVE

We compare neoadjuvant chemotherapy (CT) to neoadjuvant chemotherapy plus chemoradiation (CRT) for patients with gastric adenocarcinoma (GA).

SUMMARY OF BACKGROUND DATA

The optimal neoadjuvant therapy regimen for resectable GA is not defined.

METHODS

Utilizing data from 2 high-volume cancer centers, we analyzed patients who underwent surgery for localized GA from 1/1/2000-12/31/2017. Standard CT regimens were used according to treatment period. We compared propensity matched cohorts based on age, sex, race, histology, and clinical stage.

RESULTS

Four-hundred five patients (age 62 ± 12 year, 58% male, 56% White) were analyzed. 231 (57%) received CRT and 174 (43%) received CT. Groups differed based on histopathologic characteristics including preoperative stage (p = 0.013). To control for these differences, propensity matched cohorts of 113 CT and 113 CRT patients were compared. CRT had similar frequencies of microscopically negative resections to CT (93% vs 91%, p = 0.81), but higher rates of complete pathologic response (15% vs 4%, p = 0.003) and lower pathologic stage (p = 0.002). Completion of intended perioperative therapy occurred in 63% of CT and 91% of CRT patients (p < 0.001). Median DFS was 45mo (95%CI: 20-70) in the CT group and 113mo (95%CI: 75-151) in the CRT group (p = 0.018). Median OS was 53mo (95%CI: 30-77) versus 120mo (95%CI: 101-138); p = 0.015.

CONCLUSIONS

In this multi-institutional comparison of neoadjuvant CT and CRT for resectable GA, CRT is associated with higher rates of completed perioperative therapy, higher rates of complete pathologic response, lower pathologic stage, and improved survival.Level of Evidence: Level III.

Methylamine dehydrogenase from the obligate methylotroph Methylomonas methylovora

An obligate methyltroph Methylomonas methylovora oxidized methylamine, formaldehyde, and formate. Enzymes oxidizing these substrates were detected in a cell-free system. Phenazine methosulfate-linked methylamine dehydrogenase was purified 21-fold. The enzyme had optimum activity at pH 7.5 and was stable at 60 degrees C for 5 min. The enzyme activity was inhibited by parachloromercuric benzoate, isonicotinic acid hydrazide, mercuric chloride, and sodium borate.

Virus-like particles and lytic plaque formation in lawns of Candida albicans

The antifungal agent Aculeacin A at subinhibitory levels induced lytic plaques in lawns of Candida albicans. Electron microscopic examination of plaque lysates suspended in phosphotungstic acid revealed the presence of spherical particles 12, 18, and 28 to 30 nm in size. Particles were also found in ultrathin sections of treated C. albicans cells. The plaque lysate lost infectivity after treatment with UV light, heat treatment at 80 degrees C for 10 min, or being held at pH 2 for 30 min.

Aculeacin A resistant mutants of Candida albicans

Mutants of Candida albicans resistant to aculeacin A, a yeast cell-wall inhibitor, were isolated after mutagenesis with ultraviolet light. The parental strain was sensitive to 0.1 approximately 0.5 microgram/ml of the antibiotic. In contrast, the minimum inhibitory concentration for the mutants ranged from 50 to 200 microgram/ml. Except for papulocandin, another cell-wall inhibitor, the antibiotic susceptibility of the mutants was similar to the parental strain. The parent strain and the aculeacin resistant mutants exhibited similar morphological changes at subinhibitory levels of aculeacin and had comparable growth rates on complex media. The lipid and sterol content of the parent and the mutants were significantly different. For example, the total lipid content was two-fold higher in the mutant strains. Drug resistance in the mutants was specific for aculeacin and papulocandin and appeared to be associated with alteration in the lipid composition of membranes.

Pyridine nucleotide-linked oxidation of methanol in methanol-assimilating yeasts

An alcohol dehydrogenase linked to nicotinamide adenine dinucleotide and requiring glutathione has been isolated and partially purified from two methanol-assimilating yeasts. It differs from previously described methanol-oxidizing enzymes in pH optima, electron acceptor specificity, substrate specificity, inhibition pattern, and stability.

Cefonicid: a stable beta-lactamase inhibitor

The stability of cefonicid (SK&F 75073) towards representatives of six major classes of beta-lactamases was determined using a spectrophotometric assay. Cefonicid was stable to hydrolysis by the Type I enzyme from Enterobacter cloacae and by the enzyme from the anaerobe, Bacteroides fragilis. It was 6 to 7 times more stable than cefamandole to the Type IIIA and B enzymes from Escherichia coli, a little less stable than this antibiotic to the Type V enzyme from E. coli, and of equal stability to the Type IV enzyme from Klebsiella aerogenes. Cefonicid was a non-competitive inhibitor (Ki of 0.8 x 10(-6)M) of cephalothin hydrolysis by the Type I enzyme.

A novel inducible formaldehyde dehyrogenase of Pseudomonas sp. (RJ1)

A novel, pyridine-nucleotide-independent, inducible formaldehyde dehydrogenase acitivity was detected in cells of Pseudomonas sp. (RJ1) propagated on methylamine and oxalated. The pH optimum of the dehydrogenase was 7.0. Dichlorophenol-indophenol or potassium ferricyanide served as an electron acceptor. The rate of reduction of these electron acceptors was shown to be stimulated by phenazine methosulfate. The dehydrogenase was inhibited by parahydroxymercuric benzoate and iodoacetamide. This inhibition suggests that the enzyme contains sulfhydryl groups. The stoichiometry of the reaction in terms of oxygen uptake to formate formation was 0.5, which agrees with the theoretical value.

Odor control during post-digestion processing of biosolids through bioaugmentation of anaerobic digestion

The effects of bioaugmenting anaerobic biosolids digestion with a commercial product that contained selected strains of bacteria from genera Bacillus, Pseudomonas, and Actinomycetes, along with ancillary organic compounds containing various micronutrients were evaluated. The main objective of the study was to investigate the effects of bioaugmentation specifically on the performance of methanogenesis during anaerobic digestion, as well as on the generation and fate of odor-causing compounds during the storage of the digested biosolids. The bench-scale digester with 5 g/L bioaugment generated 29% more net CH4 than a control during the eight weeks of operation. In addition, the average residual propionic acid concentration in the bioaugmented digester was 46% lower than that in the control. The biosolids digested in the bioaugmented digester generated a negligible amount of methyl mercaptan (CH3SH) during 10 days of post-digestion storage, while CH3SH concentration in the control reached nearly 300 ppmv during the same period. Similarly peak dimethyl sulfide (CH3SCH3) generated by stored biosolids from the bioaugmented digester was only 37% of that from the control. Similar results were obtained in a subsequent short term study designed to confirm the repeatability of the findings.

Relationship between carbon source and susceptibility of Cephalosporium acremonium to selected amino acid analogues

The susceptibility of Cephalosporium acremonium to selected amino acid analogues was markedly influenced by the carbon source used in the test media. Lysine hydroxamate, beta-hydroxy norvaline, and hexafluorovaline were toxic when tested with ribose, ribose or fructose, and ribose or galactose, respectively. In contrast, thialysine and thiaisoleucine inhibited C. acremonium with glucose, fructose, galactose, sucrose, mannitol, sorbitol, and soluble starch. Neither of these analogues was toxic at levels tested when glycerol was used as a carbon source. The minimal inhibitory concentrations (MIC) of thialysine, homoserine, and alpha-methylserine were greater than 1000, greater than 1000, and 250 microgram/mL, respectively, with glycerol. In contrast, the MIC values for the same three analogues were 31, 62, and 125 microgram/mL, respectively, with mannitol. The matching of the carbon sources with the specific amino acid analogues expands the number of analogues useful for selecting derepressed mutants. Thialysine-resistant mutants (tlysR) of C. acremonium which excrete lysine were isolated on a medium containing mannitol.