Biomedical subjects

G Corzo

Publications and source records attributed to G Corzo.

11 recordsLinked to original sources

PubMed2001

IsCT, a novel cytotoxic linear peptide from scorpion Opisthacanthus madagascariensis.

A novel cytotoxic linear peptide, IsCT, was characterized from scorpion Opisthacanthus madagascariensis. It is a linear peptide with a molecular weight of 1501.9 Da composed of 13 amino acid residues without cysteines. MS/MS analysis showed that its C-terminal is amidated. The identity of IsCT is re-confirmed by comparing the chemical synthesized peptide with the natural one. IsCT demonstrated antimicrobial activity against both gram-positive and gram-negative bacteria and hemolytic activity to sheep red blood cells. Also, it can release histamine from rat peritoneal mast cells. The CD absorption suggested that IsCT had an alpha-helix configuration in aqueous TFE. IsCT is one of the shortest natural cytotoxic peptides described, and it will be a suitable model for studying peptide-lipid interactions.

Amino Acid Sequence↗

PubMed2001

Novel peptides from assassin bugs (Hemiptera: Reduviidae): isolation, chemical and biological characterization.

Three novel peptides were isolated from the venomous saliva of predatory reduviids. They were identified by mass spectrometry and HPLC analysis and consist of 34-36 amino acid residues. They are relatively homologous to the calcium channel blockers omega-conotoxins from marine cone snails and belong to the four-loop Cys scaffold structural class. Ptu1, the shortest peptide, was chemically synthesized (sPtu1) and co-eluted with its native form. Circular dichroism spectra of the sPtu1 showed a high content of beta-turns similar to that of omega-conotoxins GVIA and MVIIA. Electrophysiological experiments demonstrated that sPtu1 reversibly blocks the N-type calcium channels expressed in BHK cells.

Amino Acid Sequence↗

PubMed2000

Isolation, synthesis and pharmacological characterization of delta-palutoxins IT, novel insecticidal toxins from the spider Paracoelotes luctuosus (Amaurobiidae).

Four novel insecticidal toxins were isolated from the venom of the spider Paracoelotes luctuosus (Araneae: Amaurobiidae) and named delta-palutoxins IT1 to IT4. The four toxins are homologous 36-37 amino acid peptides reticulated by four disulfide bridges and three have amidated C-terminal residues. The delta-palutoxins are highly homologous with the previously described mu-agatoxins and curtatoxins (77-97%). The four peptides demonstrated significant toxicity against larvae of the crop pest Spodoptera litura (Lepidoptera: Noctuidae) in a microinjection bioassay, with LD50 values in the 9-50 microg per g of insect range. This level of toxicity is equivalent to that of several of the most active scorpion toxins used in the development of recombinant baculoviruses, and the delta-palutoxins appear to be insect specific. Electrophysiological experiments demonstrated that delta-palutoxin IT1, the most active toxin acts by affecting insect sodium channel inactivation, resulting in the appearance of a late-maintained sodium current, in a similar fashion to insecticidal scorpion alpha and alpha-like toxins and is thus likely to bind to channel receptor site 3. However, delta-palutoxin IT1 was distinguished by its lack of effect on peak sodium conductance, on the early phase of sodium current inactivation and the absence of a shift in the activation voltage of the sodium channels. delta-Palutoxins are thus proposed as new insecticidal toxins related to the alpha and alpha-like scorpion toxins. They will be useful both in the development of recombinant baculoviruses in agrochemical applications and also as molecular probes for the investigation of molecular mechanisms of insect selectivity and structure and function of sodium channels.

Agatoxins↗

PubMed1999

A comparison of matrix-assisted laser desorption/ionization time-of-flight and liquid chromatography electrospray ionization mass spectrometry methods for the analysis of crude tarantula venoms in the Pterinochilus group.

The search for novel pharmacological tools in spider venoms involves the need for precise and reproducible species identification methods. As an addition to morphological analysis, we have developed venom fingerprinting by reversed-phase chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) as an efficient and precise venom identification tool. In order to compare the possible use of liquid chromatography electrospray ionization mass spectrometry (LC/ESI-MS) as an additional venom characterization tool, we have applied both methodologies to the study of several tarantula venom samples in the Pterinochilus murinus group. These species possess highly active venoms yet their taxonomy remains difficult. We demonstrate that both methodologies can be successfully applied to tarantula venom characterization. MALDI-TOFMS and ESI-MS gave similar overall profiles and allowed fine discrimination of samples. At least one venom sample was proven to belong to a completely different venom group. Coupling of ESI-MS with HPLC separation afforded a new dimension in venom analysis, with clear discrimination between components of similar Mr and gave a finer picture of venom composition, number of molecular species and molecular weight distribution.

Animals↗

PubMed1999

Measurement of bile salt hydrolase activity from Lactobacillus acidophilus based on disappearance of conjugated bile salts.

Bile salt hydrolase activity of Lactobacillus acidophilus was measured based on the disappearance of sodium glycocholate and sodium taurocholate from the reaction mixture using HPLC. The amount of sodium glycocholate and sodium taurocholate that disappeared was proportional to the amount of sodium cholate that appeared in the mixture as detected by HPLC. Sodium glycocholate did not precipitate at the enzyme reaction conditions (37 degrees C and pH 5.4) for determining bile salt hydrolase activity. The bile salt hydrolase assay was insensitive to low oxidation-reduction potential when measuring bile salt hydrolase from L. acidophilus, an intestinal microorganism. However, EDTA and freezing temperatures were necessary to maintain stability of the partially purified enzyme during storage.

Amidohydrolases↗

PubMed1999

Bile salt hydrolase activity of three strains of Lactobacillus acidophilus.

Three strains of Lactobacillus acidophilus, two from human intestinal origin (016 and L1) and one from porcine intestinal origin (ATCC 43121), were tested for their bile salt deconjugation activity. The L. acidophilus ATCC 43121 had more deconjugating activity of both sodium glycocholate and sodium taurocholate at pH 6.5 than did either L. acidophilus 016 or L1. The activity of intracellular bile salt hydrolase found in strain ATCC 43121 was 14-fold higher than that in either of the other two strains. The optimum pH for deconjugation of sodium glycocholate was between 4 and 5.5 for all three strains. For deconjugation of sodium taurocholate, the optimum pH was between 3.5 and 4.5 for strains L1 and ATCC 43121 and was between pH 5 and 6 for strain O16. The molecular mass of the enzyme in all three strains of L. acidophilus was estimated to be 126 kDa by Sephadex G-200 gel filtration. All three strains exhibited more bile salt hydrolase activity towards sodium glycocholate than towards sodium taurocholate.

Amidohydrolases↗

PubMed1998

[Occupational exposure to lead in production units in Maracaibo, Venezuela].

A medical occupational study was performed in 40 workers belonging to productive units in telecommunication works, 22 to car radiator mechanics and 11 to battery repairs. A practical medical and occupational study was applied to the group and also were determined their blood lead and air lead exposure levels. Seventy-three individuals, without risk of laboral exposure to lead, without familiar, pathological and occupational antecedents, and healthy at the time of the test, to whom the blood lead levels were determined served as control group. The mean values of plumbemia in exposure workers to inorganic lead exceed the level threshold of the COVENIN 2277-85 norm (30 micrograms/dl) (Telecommunication work, 40.10 micrograms/dl, radiators mechanics, 37.40 micrograms/dl and battery repairs, 45.77 micrograms/dl), values that were significantly higher (p < 0.0001) compared with the ones obtained in the non-exposed population. The factors that can influence the variability of the results were analyzed and it was established a correlation between the plumbemia of the radiator mechanics and battery repairmen and the length of occupational period and air lead levels (p < 0.0001). The inherent factors to the climatic, occupational and personal conditions of technicians in telecommunications, are presented as elements able to explain the lack of correlation between blood lead levels and length of occupational period and air lead. The clinical findings in exposed workers were unspecific. The workers do not practice or follow the basic sanitary regulations, personal protection and industrial security. This work will contribute to establish a basic description, to further and more complex observational prospective studies in order to determine the occurrence of alterations that are derived from occupational lead exposure.

Adolescent↗

PubMed1998

[Spirometry in workers in a wheat-processing industry].

In order to determine both clinical and spirometric changes due to high environmental concentrations of wheat dust at a wheat processing plant mill, 48 exposed men and 48 age and antroprometrically-matched, non-exposed apparently healthy men were studied. In both groups a medical and occupational history were taken, and spirometric measurements were carried out, that included Forced Vital Capacity (FVC), Forced Expiratory Volume at the first second (FEV1), Peak Flow Rate (PFR), Forced Percentual Expiratory Volume (FEV%), Forced Percentual Vital Capacity (FVC%), Forced Expiratory Flow at 25% (FEV25%), at 50% (FEV50%) and at 75% (FEV75%) of their Forced Vital Capacity, which were analyzed through Corzo's predictive equations and the lung deterioration's criteria by USA's Thoracic Association. The environmental wheat dust was determined by gravimetry and its concentration was higher than the legally admitted (3/5, 60%). There was a decrease in the PFR, FEV%, FEV25% and FEV75%. (p < 0.05). In addition, 4 restrictive and 1 obstructive syndrome were detected in the exposed workers and none in the control group. The spirometric values diminished in a positive correlation with the time of exposure and smoking habits. There was no correlation between the clinical findings and the dust concentration but it did exist with the spirometric values. It is concluded that in this plant, the wheat dust exposed workers have a diminished spirometric values.

Adult↗

PubMed1997

N-acyl amino acid biosynthesis in marine bacterium, Deleya marina.

We reported previously that the marine bacterium, Deleya marina (ATCC 25374), produced N-acyl leucine and isoleucine, in which nonhydroxy fatty acid was linked to alpha-amino group of amino acid. Further analysis of bacterium lipids revealed the additional production of N-acyl ornithine. The N-acyl ornithine had a 3-hydroxy fatty acid linked by an amide bond to a-amino group of ornithine and a nonhydroxy fatty acid esterified to the hydroxy group of the 3-hydroxy fatty acid. N-acyl ornithine was located in the cell membrane and N-acyl leucine and isoleucine in cytoplasm. N-acyl ornithine is thought to be a functional analogue of phosphatidylethanolamine (PE) because of their similar structure. PE replacement into N-acyl ornithine in the cell membrane under phosphate-limited conditions was observed with other bacteria, so we anticipated the nonbiosynthesis of N-acyl ornithine under phosphate-sufficient conditions. We did not anticipate that N-acyl leucine and isoleucine in cytoplasm, whose structure is dissimilar to that of PE, would be replaced into PE in the cell membrane. Neither N-acyl leucine, N-acyl isoleucine, nor N-acyl ornithine was biosynthesized under phosphate-sufficient condition. Thus, we report here for the first time that N-acyl amino acids in cytoplasm were not biosynthesized under phosphate-sufficient conditions.

Bacteria↗

PubMed1997

[Lung function in workers in a chicken slaughterhouse in the city of Maracaibo, Venezuela].

In order to evaluate the respiratory health status in workers exposed to antigenic substances (chicken feathers, serum and dropping), typical of usual practice in the avian slaughter-house, pulmonary function was studied on 49 exposed workers, and in a sample of 49 people with similar anthropometric characteristics, non exposed to these substances, by means of occupational-medical history, spirometric tests, hematologic and biochemical tests, and postero-anterior chest x-rays. The values for the spirometric parameters varied with sex, age, weight, size, smoking habits, length of employment and exposure time, and there were no significant differences between exposed and control groups as a whole; showing significant differences with decreasing values for CVF, VEF1, PFE, FEF-25% and FEF-50% in the intermediate zone workers, and in subjects with short exposure time (< 1 year). Prevalence of clinical findings in the exposed population was significantly higher than the non exposed group (p < 0.001). Laboratory tests showed reduction of monocytes cells in the exposed group (p < 0.05) in addition, in the exposed women there was an increase of the eosinophiles, total proteins and globulines (p < 0.05). The frequency of radiographic findings was significantly higher in the exposed group (p < 0.006), and they were no specific. The lack of association between clinical findings, laboratory and radiographic findings, with the spirometric results, could be explained by the short period of exposure, individual and collectives hygienic conditions and size of the sample.

Abattoirs↗

PubMedDate not supplied

Structure and pharmacology of spider venom neurotoxins.

Spider venoms are complex mixtures of neurotoxic peptides, proteins and low molecular mass organic molecules. Their neurotoxic activity is due to the interaction of the venom components with cellular receptors, in particular ion channels. Spider venoms have proven to be a rich source of highly specific peptide ligands for selected subtypes of potassium, sodium and calcium channels, and these toxins have been used to elucidate the structure and physiological roles of the channels in excitable and non-excitable cells. Spider peptides show great variability in their pharmacological activity and primary structure but relative homogeneity in their secondary structure. Following diverse molecular evolution mechanisms, and in particular selective hypermutation, short spider peptides appear to have functionally diversified while retaining a conserved molecular scaffold. This paper reviews the composition and pharmacology of spider venoms with emphasis on polypeptide toxin structure, mode of action and molecular evolution.

Amino Acid Sequence↗