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Biomedical subjects

J M Domínguez

Publications and source records attributed to J M Domínguez.

At least 19 recordsLinked to original sources
PubMed1999

Romifidine, medetomidine or xylazine before propofol-halothane-N2O anesthesia in dogs.

The objective of this paper was to evaluate romifidine as a premedicant in dogs prior to propofol-halothane-N2O anesthesia, and to compare it with the other alpha2-agonists (medetomidine and xylazine). For this, ten healthy dogs were anesthetized. Each dog received 3 preanesthetic protocols: atropine (10 microg/kg BW, IM), and as a sedative, romifidine (ROM; 40 microg/kg BW, IM), xylazine (XYL; 1 microg/kg, IM), or medetomidine (MED; 20 microg/kg BW, IM). Induction of anesthesia was delivered with propofol 15 min later and maintained with halothane and N2O for one hour in all cases. The following variables were registered before preanesthesia, 10 min after the administration of preanesthesia, and at 5-minute intervals during maintenance: PR, RR, rectal temperature (RT), MAP, SAP, and DAP. During maintenance, arterial oxygen saturation (SpO2), end-tidal CO2 (EtCO2) and percentage of halothane necessary for maintaining anesthesia (%HAL) were also recorded. Induction dose of propofol (DOSE), time to extubation (TE), time to sternal recumbency (TSR) and time to standing (TS) were also registered. The statistical analysis was carried out during the anesthetic period. ANOVA for repeat measures revealed no differences between the 3 groups for PR and RR; however, MAP, SAP and DAP were higher in the MED group; SpO2 was lower in MED and EtCO2 was lower in ROM; %HAL was higher in XYL. No statistical differences were observed in DOSE, TE, TSR or TS. Percentage of halothane was lower in romifidine and medetomidine than in xylazine premedicated dogs also anesthetized with propofol. All the cardiorespiratory variables measured were within normal limits. The studied combination of romifidine, atropine, propofol, halothane and N2O appears to be a safe and effective drug combination for inducing and maintaining general anesthesia in healthy dogs.

Adrenergic alpha-Agonists↗
PubMed1998

Sordarins: A new class of antifungals with selective inhibition of the protein synthesis elongation cycle in yeasts.

GR135402, a sordarin derivative, was isolated in an antifungal screening program. GR135402, sordarin, and derivatives of both compounds were evaluated for their ability to inhibit cell-free translational systems from five different pathogenic fungi (Candida albicans, Candida glabrata, Candida krusei, Candida parapsilosis, and Cryptococcus neoformans). The activity profile of GR135402 is extended to other chemical compounds derived from sordarin. Experimental results indicate that sordarin analogs exert their antifungal effects by specifically inhibiting the protein synthesis elongation cycle in yeasts but do not affect protein synthesis machinery in mammalian systems. Intrinsically resistant strains owe their resistance to differences in the molecular target of sordarins in these strains. Preliminary studies performed to elucidate the mode of action of this new class of antifungal agents have shown that the putative target of sordarins is one of the protein synthesis elongation factors.

Antifungal Agents↗
PubMed1998

Identification of elongation factor 2 as the essential protein targeted by sordarins in Candida albicans.

The target for sordarins in Candida albicans has been elucidated. Kinetic experiments of sordarin inhibition as well as displacement experiments showed that the formation of a sordarin-target complex follows a reversible mechanism. Binding of tritiated drug to the target is enhanced in the presence of ribosomes. Isolation of the target by classical protein purification methods has allowed us to identify it as elongation factor 2. This is in agreement with the nature of sordarin derivatives as specific inhibitors of the elongation cycle within protein synthesis in yeasts.

Amino Acid Sequence↗
PubMed1993

Mode of action of endoglucanase III from Trichoderma reesei.

Endoglucanase III (EG III) was purified to homogeneity from the culture medium of Trichoderma reesei QM 9414. It has a molecular mass of 48 kDa, and an isoelectric point of 5.1. Maximal activity was observed between pH4 and 5. Celloligosaccharides and their chromophoric derivatives were used as substrates, and the reaction products were analysed by quantitative h.p.l.c. Nucleophilic competition experiments (between methanol and water) allowed unequivocal assessment of cleavage sites. EG III preferentially released cellobiose (or the corresponding glycoside) from the reducing end of the higher cellodextrins. A putative binding model containing five subsites is proposed. The pH-dependence of 4'-methylumbelliferyl beta-cellotrioside hydrolysis indicates the presence of a protonated group with a pK 5.5 in the reaction mechanism, and the possible involvement of a carboxy group is corroborated by a temperature study (delta Hion = -15.9 J/mol). This, together with independent evidence from affinity-labelling experiments [Tomme, Macarrón and Claeyssens (1991) Cellulose '91, New Orleans, Abstr. 32] and n.m.r. studies [Gebbler, Gilkes, Claeyssens, Wilson, Béguin, Wakarchuk, Kilburn, Miller, Warren and Withers (1992) J. Biol. Chem. 267, 12559-12561], favours the assumption of a lysozyme-type (retention of configuration, two essential carboxy groups) mechanism for this family A cellulase.

Bacterial Proteins↗
PubMed1993

Chemical modification of beta-glucosidase from Trichoderma reesei QM 9414.

The inhibition of beta-glucosidase from Trichoderma reesei QM 9414 by several specific reagents was studied. Diethylpyrocarbonate (DEP) nearly abolished the enzyme activity at concentrations above 10 mM. The presence of substrate or analogs protected the enzyme against inactivation. The reaction followed pseudo-first order kinetics with a second-order rate constant of 0.02 mM-1.min-1. The pH-dependence of the inactivation showed the involvement of a group with a pK of 5.2. Difference spectra at 242 nm and the reversal of the inactivation in the presence of 1 M hydroxylamine indicated the modification of histidine residues. Statistical analysis of residual fractional activity versus the number of modified histidine residues indicated that one histidine residue is essential for catalysis. p-Hydroxymercuribenzoate completely inhibited the enzyme at concentrations of the reagent above 2 mM. Substrate or analogs protected the enzyme against inactivation. The reaction followed pseudo-first order kinetics with a second-order rate constant of 0.002 mM-1.min-1. Treatment of the modified enzyme with 5,5'-dithio-bis(2-nitrobenzoic acid) (DTNB) showed that one cysteine residue was essential for activity. At pH 5.0 2-ethoxy-1-ethoxy-carbonyl-1,2-dihydroquinoline (EEDQ) inactivated the enzyme according to pseudo-first order kinetics with a second-order rate constant of 0.12 min-1. The pH-dependence of the inactivation showed the involvement of a group with a pK of 5.64, indicating the modification of a carboxyl group essential for activity.

Diethyl Pyrocarbonate↗
PubMed1977

Smear-positive and culture-negative results of routine sputum investigations for the detection and therapy control of pulmonary tuberculosis.

The frequency of smear-positive and culture-negative results (M + C-) is an important factor in the supervision by the Central Laboratory of its own activities and those of the laboratories in the periphery. Under the conditions of the present study, which included evaluation of 6415 specimens positive on smear during 5 years and studied simultaneously by microscopy and culture, about one half of the M+C- results (3% of the total) were thought to be probably laboratory errors and the other half were from patients being treated by chemotherapy. It is necessary to know, at least approximately, the size of this latter group of persons before the contribution of laboratory errors can be estimated and the necessary action taken to reduce their frequency.

Bacteriological Techniques↗
PubMedDate not supplied

[Use of temporary pacemaker programming in VVT mode for the treatment of recurrent ventricular tachycardia].

This is a report of a 59-year-old man with a Björk aortic prosthetic valve and mitral commissurotomy with left ventricular dysfunction and recurrent ventricular tachycardia (VT) in spite of antiarrhythmic therapy with amiodarone. Serial electrophysiologic studies were performed using standard ventricular extrastimulation technique. During these studies, sustained VT was induced and terminated by programmable extrastimulus pacing. The usual rhythm of the patient was atrial fibrillation with slow ventricular rate. The Medtronic Spectrax model 5985 pulse generator was implanted. A temporary program converts this device from inhibited (VVI) to triggered (VVT) mode, permitting programmed ventricular stimulation through synchronization with chest wall stimulation by a standard external programmable stimulator. During episodes of VT the pacemaker was temporary programmed to the VVT mode with a refractory period of 220 msec. With the chest wall stimulation by a electrophysiology stimulator it was possible to convert the VT with 2 or 3 synchronised extra stimulus. Thanks to the triggered mode the pacemaker will fire when the chest wall is stimulated, working as an external electrophysiology stimulator.

Aortic Valve↗