Gastroplastía endoscópica antirreflujo: análisis experimental de su efecto en la presión del esfínter esofágico inferior / Antireflux endoscopic gastroplasty: experimental analysis of it effect in the inferior esophageal sphincter

El objetivo de este trabajo es evaluar en forma experimental el efecto de la cirugía endoscópica antirreflujo en la presión del esfínter esofágico inferior en perros. Se utilizó 5 perros mestizos que fueron mantenidos en ayunas por 12 horas previo procedimiento. Luego fueron pesados y anestesiados con una dosis inicial de 25 mg/kg de pentotal i.v. y bolos de 10 mg/kg según necesidad. Se introdujo una sonda perfundida de tres canales, conectada a un transductor de presión y un polígrafo Beckmann R411, determinándose la presión y ubicación del esfínter esofágico inferior (EEI). A continuación se realizó una endoscopía y se instaló un sobretubo esofágico. Se instaló el mecanismo de sutura endoscópica en un endoscopio Olympus CF-1TS2, se colocaron 2 puntos 1 cm bajo la línea Z a la derecha de la curvatura menor y luego fueron anudados para formar un pliegue. El procedimiento se repitió pero colocando los puntos a la izquierda de la curvatura. A continuación se midió nuevamente la presión del EEI con la misma técnica. Los animales fueron mantenidos con libre acceso al alimento y agua por 7 días. Después de este período fueron nuevamente anestesiados y se midió nuevamente la presión del EEI. Los resultados confirman que la gastroplastía endoscópica es capaz de aumentar en forma significativa la presión del EEI en perros

BICAP tumor probe en el tratamiento paliativo de la estenosis esofágicas malignas / BICAP tumor probe in the treatment of malignant sophageal stenosis

Background: BICAP tumor probe is a device that consists in an energy source and olives that deliver bipolar electricity. It can be used for the fulguration of esophageal tumors after endoscopic dilatation. Aim: To report the experience in the treatment of malignant esophageal stenoses using the BICAP tumor probe. Patients and methods: Patients with advanced esophageal tumors in aphagia, that were not candidates for palliative surgery were included in this study. After endoscopic dilatation, the tumor was fulgurated with the BICAP tumor probe. Results: Twenty one patients (nine male, aged 43 to 91 years old) were treated with the device. A mean of 1.3 sessions with BICAP were necessary to obtain tumor permeabilization, which was obtained in all patients. One patient died of pneumonia 15 days after the procedure. All other patients were ingesting liquid or semisolid diets after two months of follow up. Mean survival after the procedure was 3.8 months. Conclusions: Electrical fulguration of esophageal tumors is a valid therapeutic alternative in aphagic patients

Isolation, structure determination and biological activity of A-16686 factors A' 1, A' 2 and A' 3 glycolipodepsipeptide antibiotics.

When Actinoplanes strain ATCC 33076, the producer of A-16686 A1, A2 and A3 complex, is fermented in a suitable medium three additional factors, designated A' 1, A' 2 and A' 3 are produced. These were isolated and characterized, and were shown to differ from the parent components of the original complex by lacking one mannose unit. Bioconversion of A factors into A' factors was achieved by incubation with the mycelium of Actinoplanes ATCC 33076. Factor A' 2 has better antibacterial activity than A2 against some bacteria.

Sequence determination of actagardine, a novel lantibiotic, by homonuclear 2D NMR spectroscopy.

By combination of several 1H NMR techniques, the sequence of actagardine has been elucidated. It has been shown that it is a tetracyclic 19-residue peptide antibiotic. It differs from the previously described lanthionine-containing peptide antibiotics belonging to the lantibiotic class.

Synthesis and biological activity of some amide derivatives of the lantibiotic actagardine.

A series of basic carboxamides of actagardine (1), a lantibiotic possessing good antistreptococcal activity, were synthetized. Some physico-chemical characteristics, in particular charge and lipophilicity, that influence water solubility were determined. The in vitro and in vivo activity was evaluated. The monocarboxamides were generally more active than actagardine against selected Gram-positive bacteria. The 3,3-dimethylamino-1-propylamide hydrochloride (4) showed good water solubility, bactericidal action and favourable antibacterial activity and it appears to be a suitable drug for further investigation.

N15-alkyl and N15,N15-dialkyl derivatives of teicoplanin antibiotics.

The synthesis and the biological properties of a series of N15-alkyl and N15,N15-dialkyl derivatives of teicoplanin A2, its pseudoaglycones and aglycone are described. The alkylation of the terminal amino group did not affect the ability of these teicoplanin derivatives to bind with Ac2-L-Lys-D-Ala-D-Ala, a synthetic model of the antibiotic's target peptide in bacterial cell walls, but influenced their in vitro and in vivo antimicrobial activities to a different extent, depending on the structure and length of the alkyl chains and the type and number of sugars present.

Synthesis and biological activity of some derivatives of rifamycin P.

A series of derivatives of rifamycin P, an antibiotic produced by fermentation of a mutant strain of Nocardia mediterranea or by chemical modification of rifamycin S, have been prepared. The structures of these compounds were determined by 1H NMR, IR, UV, and LC/MS. Their in vitro and in vivo antibacterial activities in comparison with rifampicin and two other rifamycins under investigation were evaluated. The derivatives were more active than rifamycin P against Mycobacterium avium complex and other slowly and rapidly growing nontuberculous mycobacteria which frequently cause systemic infection in patients with AIDS. 2'-(Diethylamino)rifamycin P (P/DEA) appears suitable for further investigation.

Ramoplanin: a review of its discovery and its chemistry.

Ramoplanin is a novel antibacterial agent with characteristics that make it suitable for development as a topical treatment for acne, infected wounds, and for treatment of antibiotic-associated diarrhoea. In this paper, the authors will review the discovery process and the descriptive chemistry of this novel molecular entity.

Dechloro teicoplanin antibiotics.

Mono- and didechlorinated derivatives of the antibiotic teicoplanin, its pseudoaglycones and aglycone, and of one amide and ester of deglucoteicoplanin were prepared under selective reductive conditions. The selectivity and rate of dehalogenation were studied and compared to those of vancomycin and deglucovancomycin. The influence of the chlorine substituents on the mechanism of action and antibacterial activity of teicoplanin antibiotics was also investigated.

Laser-induced vaporization mass spectrometry of rifamycins.

The mass spectra of many rifamycins cannot be obtained by electron ionization (EI) owing to their thermal decomposition. When a laser beam is used to vaporize the sample through an optic fibre inserted in a hollow probe which reaches the sample cup, decomposition is minimized and the EI spectra show abundant molecular ions and fragments of structurally high diagnostic value. These ionic species are easily observed owing to the lack of chemical noise often present in soft ionization methods, such as direct liquid chemical ionization and fast atom bombardment.

Ramoplanin (A-16686), a new glycolipodepsipeptide antibiotic. III. Structure elucidation.

By combination of chemical, 1H and 13C NMR, and mass spectrometric studies, the structures of the three components of the antibiotic ramoplanin (A-16686), produced by Actinoplanes sp. ATCC 33076, have been elucidated. All the components have structures formed by a common depsipeptide skeleton carrying a dimannosyl group and are differentiated by the presence of various acylamide moieties, derived from C8, C9 and C10 fatty acids.

Ramoplanin (A-16686), a new glycolipodepsipeptide antibiotic. IV. Complete sequence determination by homonuclear 2D NMR spectroscopy.

Homonuclear 2D NMR spectroscopy double quantum filter correlation spectroscopy (DQF-COSY), relayed-COSY, nuclear Overhauser enhancement spectroscopy (NOESY), and DQF-relayed-NOESY) allowed the complete determination of the core depsipeptide of antibiotic ramoplanin (A-16686). In particular, the DQF-relayed-NOESY experiments were essential in assigning the single signals close to the diagonal.

Structure and biological activity of lipiarmycin B.

Actinoplanes deccanensis ATCC 21983, the producer of antibiotics lipiarmycin A3 and A4, furnished also a related antibiotic designated lipiarmycin B, active against Gram-positive bacteria, including anaerobes, and against Neisseria. The structures of the two major components, B3 and B4, were elucidated from their physico-chemical properties, 1H and 13C NMR spectra and fast atom bombardment mass spectra data in comparison with lipiarmycins A3 and A4.

Synthesis and biological activity of some esters of the N-acetylglucosaminyl aglycone and of the aglycone of teicoplanin.

A series of ester derivatives of teicoplanin-N-acetylglucosaminyl aglycone (T-A3-2) and deglucoteicoplanin was prepared starting from teicoplanin and from the corresponding deglycosylation compounds. The modification of the ionic and lipophilic character of the parent antibiotic strongly influences the spectrum of antibacterial activity in vitro.

Teicoplanin: chemical, physico-chemical and biological aspects.

The structure determination and the physico-chemical properties of teicoplanin, a new glycopeptide antibiotic of the vancomycin-ristocetin family are presented. Some biological studies and the mechanism of action at the molecular level are discussed. Analytical test methods, such as HPLC assay, bioassay and enzymatic assay are described. The antimicrobial activity of teicoplanin and of some relevant acid and basic hydrolysis products are also discussed.

Teicoplanin, antibiotics from Actinoplanes teichomyceticus nov. sp. VIII. Opening of the polypeptide chain of teicoplanin aglycone under hydrolytic conditions.

Hydrolysis of teicoplanin (a complex of five closely related factors plus one, more polar component) under selected conditions (acids in a biphasic hydroalcoholic medium) gives the single aglycone with good yields. When the reaction is carried out in homogeneous hydroalcoholic phase the removal of the sugars yields two new compounds. On the basis of fast atom bombardment mass spectra (FAB-MS), acid-base titration, IR, UV and 1H NMR analyses it has been demonstrated that these compounds are two diastereoisomers; they differ from the teicoplanin aglycone in having additional carboxyl and amino groups derived from the hydrolysis of an amide bond. Although the molecular shape of the new aglycones is greatly modified, they still maintain some antibacterial activity which might be correlated with residual binding ability towards the terminal D-alanyl-D-alanine residue of the cell-wall mucopeptides.

Teicoplanin, antibiotics from Actinoplanes teichomyceticus nov. sp. VII. Preparation and NMR characteristics of the aglycone of teicoplanin.

Several hydrolytic reactions that transform teicoplanin or its pseudo-aglycones into the aglycone with good yields are described. The most interesting approach is hydrolytic removal of the sugars in benzyl alcohol with the formation of the aglycone benzyl ester which is then submitted to hydrogenolysis. A detailed description of the 1H and 13C NMR spectra of the teicoplanin aglycone hydrochloride is presented. All the signals were attributed to the hydrogen and carbon atoms using homo and heteronuclear COSY. The relevant interactions through space between the hydrogen atoms were obtained by NOE. The structural aspects are discussed in terms of the well-known mechanism of action of the glycopeptide antibiotics.

Synthesis and antibacterial activity of some derivatives of the antibiotic thermorubin.

A series of derivatives has been prepared from the antibiotic thermorubin, some of which show a substantial modification of the original structure. The antibacterial activities are reported.

Physico-chemical and biological properties of actagardine and some acid hydrolysis products.

Actagardine (originally designated as metabolite B or gardimycin) is a polypeptide antibiotic produced by fermentation of Actinoplanes strains ATCC 31048 and 31049. During the course of repeated fermentations two new compounds, coded D and E, were isolated. Some physico-chemical and biological characteristics of actagardine and of both compounds are presented. Compound D is derived from chemical transformation of actagardine.