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1.
Actas Urol Esp (Engl Ed) ; 43(2): 99-105, 2019 Mar.
Article in English, Spanish | MEDLINE | ID: mdl-30287138

ABSTRACT

INTRODUCTION: UI after RP is a factor that has a major impact on patients' quality of life and the associated healthcare costs. The definition of UI is very variable in the literature. Similarly, a great many predictors have been studied that affect recovery of continence after surgery, the most important of which are intraoperative. MATERIAL AND METHODS: a retrospective and observational study performed between September 2008 and March 2015. We studied intraoperative factors through visualisation using a video editor of 148 patients who underwent robot-assisted radical prostatectomy, together with other perioperative factors associated with continence, and described in the literature. We assessed continence through ICQ questionnaires, urinary loss calculated by pad count, and clinical interview in the first, third, sixth month and at one year after surgery. We defined continence as not having to use a pad or using a pad for protection socially, or an ICQ ≤ 7. We used binary and lineal logistic regression analysis to study the relationship between the intraoperative and perioperative variables on urinary continence measured at the first, third, sixth month and one year after the operation, and on continence stability. RESULTS: In our study, 72.9% of the patients were continent at one year after surgery with a mean continence stabilisation time at 4.3 months. In our lineal logistic regression analyses we found no significant relationship with the continence variable analysed during the first year. In the lineal logistic regression analysis we found that tension-free sutures had a direct positive effect (P≤.05) on the stability time of continence, as well as the urinary losses measured in the first month after surgery. CONCLUSION: In conclusion, we found in our study that the tension-free sutures were able to help towards early stability of continence. We found no other intraoperative predictors that influenced urinary continence. The urinary losses measured in the first month related to early recovery of continence.


Subject(s)
Monitoring, Intraoperative , Prostatectomy/methods , Robotic Surgical Procedures , Urinary Bladder/diagnostic imaging , Urinary Bladder/physiology , Video Recording , Humans , Male , Middle Aged , Monitoring, Intraoperative/methods , Retrospective Studies
2.
Anal Bioanal Chem ; 394(2): 575-82, 2009 May.
Article in English | MEDLINE | ID: mdl-19290510

ABSTRACT

A piezoelectric immunosensor was tested for ochratoxin A (OTA) mycotoxin detection through the immobilization of OTA-bovine serum albumin (OTA-BSA) conjugate on gold-coated quartz crystals (AT-cut/5 MHz). Immunoassays were performed in a flow-injection system through frequency decreases in a quartz-crystal microbalance (QCM) because of a mass increasing during immunoreaction with anti-OTA antibodies. Three immobilization procedures for OTA-BSA (direct adsorption and covalent attachment to two alkane thiol self-assembled monolayers) were characterized with QCM in real time. Covalent attachment of the OTA-BSA conjugates through gold nanoparticles was also tested for amplifying the signal. Binding of the excess of antibodies to the immobilized OTA in an indirect competitive analysis decreased linearly the resonant frequency in the range of the OTA concentration from 10 to 128 ng/mL, with a detection limit of 8 ng/mL (signal/noise ratio of 3). A pepsin 2 mg/mL (pH = 2.1) solution was used to release antigen-antibody complexes, regenerating the biorecognition surface.


Subject(s)
Antibodies/immunology , Biosensing Techniques/methods , Immunoassay/methods , Mycotoxins/analysis , Ochratoxins/analysis , Ochratoxins/immunology , Quartz , Animals , Calibration , Cattle , Crystallization , Electrons , Gold/chemistry , Mycotoxins/immunology , Serum Albumin, Bovine , Time Factors
3.
Exp Parasitol ; 115(1): 25-31, 2007 Jan.
Article in English | MEDLINE | ID: mdl-16843460

ABSTRACT

Giardia lamblia is a parasite that causes giardiasis in humans and other mammals. The common treatment includes different classes of drugs, which were described to produce unpleasant side effects. Mentha x piperita, popularly known as peppermint, is a plant that is frequently used in the popular medicine to treat gastrointestinal symptoms. We examined the effects of crude extracts and fractions from peppermint against G. lamblia (ATCC 30888) on the basis of trophozoite growth, morphology and adherence studies. The methanolic, dichloromethane and hexanic extracts presented IC(50) values of 0.8, 2.5 and 9.0microg/ml after 48h of incubation, respectively. The aqueous extract showed no effect against the trophozoites with an IC(50)>100microg/ml. The aqueous fraction presented a moderate activity with an IC(50) of 45.5microg/ml. The dichloromethane fraction showed the best antigiardial activity, with an IC(50) of 0.75microg/ml after 48h of incubation. The morphological and adhesion assays showed that this fraction caused several alterations on plasma membrane surface of the parasite and inhibited the adhesion of G. lamblia trophozoites. Cytotoxic assays showed that Mentha x piperita presented no toxic effects on the intestinal cell line IEC-6. Our results demonstrated antigiardial activity of Mentha x piperita, indicating its potential value as therapeutic agent against G. lamblia infections.


Subject(s)
Giardia lamblia/drug effects , Mentha piperita/chemistry , Animals , Cell Adhesion/drug effects , Cell Line , Dose-Response Relationship, Drug , Giardia lamblia/growth & development , Giardia lamblia/metabolism , Giardia lamblia/ultrastructure , Humans , Inhibitory Concentration 50 , Intestines/cytology , Intestines/drug effects , Mentha piperita/toxicity , Microscopy, Electron, Transmission , Microscopy, Video , Plant Extracts/pharmacology , Plant Extracts/toxicity , Trophozoites/drug effects , Trophozoites/growth & development , Trophozoites/metabolism , Trophozoites/ultrastructure
4.
Med. mil ; 62(3): 161-163, jul.-sept. 2006. tab
Article in Es | IBECS | ID: ibc-054866

ABSTRACT

En la literatura se encuentra ampliamente descrita la relación entre el desarrollo de una hiponatremia y el tratamiento con diuréticos tiazídicos y en asociación. Aportamos un caso llamativo por la intensidad de la hiponatremia (Na+p: 104 mEq/L), que respondió bien al tratamiento con suero salino hipertónico y cuyo diagnóstico de certeza se llevó a cabo mediante el estudio del aclaramiento de agua libre, aclaración de agua libre de electrolitos y del gradiente trastubular de potasio. Proponemos el abordaje diagnóstico de esta entidad mediante el uso de éstos conceptos y el control riguroso de factores de riesgo en pacientes susceptibles de desarrollar esta complicacion


In the literatura it is found widely described, the relationship between development o fan hyponatremia and the prescription of thiazidic and mixed diuretic. We contribute with a notorius case, by the intensity of the hyponatremia, that responded well to treatment with hypertonic saline serum and whose certainly diagnosis was carried out by the study of the free water clearance, free water electrolytes clearance and transtubular potassium gradient. We propose the diagnostic approach of this entity by the use of these concepts with the accuracy control of risk factors in susceptible patients to develop such complication


Subject(s)
Female , Aged , Humans , Hyponatremia/chemically induced , Amiloride/adverse effects , Hydrochlorothiazide/adverse effects , Risk Factors , Osmolar Concentration , Diagnosis, Differential
5.
Anal Bioanal Chem ; 377(2): 273-80, 2003 Sep.
Article in English | MEDLINE | ID: mdl-12923606

ABSTRACT

Cholesterol amperometric biosensors constructed with enzymes entrapped in electropolymerized layers of polypyrrole and poly-naphthalene derivative polymers are compared. The biosensors are based on entrapment of cholesterol oxidase and/or cholesterol esterase in monolayer or multilayer films electrochemically synthesised from pyrrole, 1,8-diaminonaphthalene (1,8-DAN), and 1,5-diaminonaphthalene (1,5-DAN) monomers. Seven configurations were assayed and compared, and different analytical properties were obtained depending on the kind of polymer and the arrangement of the layers. The selectivity properties were evaluated for the different monolayer and bilayer configurations proposed as a function of the film permeation factor. All the steps involved in the preparation of the biosensors and determination of cholesterol were carried out in a flow system. Sensitivity and selectivity depend greatly on hydrophobicity, permeability, compactness, thickness, and the kind of the polymer used. In some cases a protective outer layer of non-conducting poly( o-phenylenediamine) polymer improves the analytical characteristics of the biosensor. A comparative study was made of the analytical performance of each of the configurations developed. The biosensors were also applied to the flow-injection determination of cholesterol in a synthetic serum.


Subject(s)
Biosensing Techniques , Cholesterol Oxidase/chemistry , Cholesterol/analysis , Enzymes, Immobilized/chemistry , Naphthalenes/chemistry , Polymers/chemistry , Pyrroles/chemistry , Sterol Esterase/chemistry , Electrochemistry , Sensitivity and Specificity
6.
Plant Dis ; 86(5): 558, 2002 May.
Article in English | MEDLINE | ID: mdl-30818683

ABSTRACT

Cashew nut (Anacardium occidentale) is one of the most important cash crops of northeastern Brazil. A new disease, named here as black branch dieback, caused by Lasiodiplodia theobromae, was observed causing serious damage on as many as 30% of the trees in some orchards in both coastal and inland semiarid cashew-growing areas of Ceará and Piauí states of Brazil, respectively. The disease symptoms are first observed as darkened, elongated lesions on stems near the branch apexes of herbaceous tissues. Gum exudation is common from lesions, which expand rapidly to affect the entire branch, leading to branch death. Diseased plants were collected, and L. theobromae was consistently isolated from canker tissues. Fresh mycelial disks of the fungus were used for artificial inoculation of healthy plants. Shoots of young cashew plants were inoculated on the apex by inserting a 3-mm plug taken from actively growing colonies on potato dextrose agar into an incision made with a sterile scalpel. Agar plugs with no mycelium were placed into incised plant shoots to serve as controls. Plants were incubated in a greenhouse at 28°C. Symptoms developed within 15 days after inoculation. Artificially inoculated plants showed symptoms similar to those that were naturally infected. L. theobromae was consistently reisolated from inoculated plants. The disease seems to occur throughout the year, but it spreads faster during the rainy season. A contagious disease pattern within the orchard was observed with a decreasing gradient from the orchard perimeter to the interior of the field, suggesting an external source of primary inoculum. All improved dwarf cashew clones were susceptible, but the newly released clone END-189 was the most susceptible. Black branch dieback may reduce tree growth, nut yield, and eventually cause plant death. Plant susceptibility is not related to its age however; only herbaceous tissues are vulnerable to natural infection. A similar disease on floral shoots of cashew caused by L. theobromae was reported by Olunloyo and Esuruoso in Nigeria (1). To our knowledge, this is the first report of L. theobromae causing branch dieback in cashew orchards in Brazil. Reference: (1) O. A. Olunloyo and O. F. Esuruoso. Plant Dis. 59:176, 1975.

7.
J Nat Toxins ; 10(2): 99-109, 2001 May.
Article in English | MEDLINE | ID: mdl-11405281

ABSTRACT

Although Tityus trivitattus is the only scorpion species reported to cause severe human envenomation in Argentina, no previous studies on its venom have been done. Telson homogenates from T. trivitattus specimens collected in Santiago del Estero, Cordoba, and Buenos Aires were employed to study their protein composition and toxicity to mice. Regardless of the site of collection, electrophoretic analysis showed bands at 205, 150, 100, 40, 32, and 13 kDa or smaller. FPLC gel filtration showed three major peaks and 6-8 minor peaks with similar elution volumes. One of the minor peaks from FPLC containing a component of approximately 8 kDa was lethal to mice. Mice injected intravenously with different doses of homogenates presented severe autonomic signs like tachypnea, tachycardia, sialorrhea, lacrimation, profuse sweating, diarrhea, dyspnea, and death. Pathology studies of lungs showed severe congestion of alveolar capillaries, pulmonary edema, and hemorrhagic areas. The kidneys showed glomerular as well as tubular lesions and exocrine glands showed areas of necrosis. The calculated LD50 was 0.38 +/- 0.08 telsons per 20 g mouse, which suggests a lethal potency similar to that of T. serrulatus venom. The lethal potency of 5.0 LD50 of T. trivitattus telson homogenate was neutralized by both an anti-T. trivitattus and a heterologous anti Tityus with ED50 values of 41 +/- 19 and 170 +/- 42 microl, respectively.


Subject(s)
Autonomic Nervous System/drug effects , Kidney Glomerulus/pathology , Scorpion Venoms/adverse effects , Scorpions , Animals , Chromatography, Gel , Exocrine Glands/pathology , Hemorrhage/chemically induced , Infusions, Intravenous , Lethal Dose 50 , Lung/pathology , Mice , Necrosis , Pulmonary Edema/chemically induced , Scorpion Venoms/chemistry
8.
J Pharm Biomed Anal ; 24(1): 51-63, 2000 Dec.
Article in English | MEDLINE | ID: mdl-11108539

ABSTRACT

Different configurations based on an amperometric biosensor with cholesterol oxidase entrapped in a polypyrrole film have been developed with a view to improving the analytical properties of this biosensor. The alternatives considered involve the simultaneous entrapment of the enzyme and a charge-transfer mediator as well as previous platinization of the surface of the Pt electrode. Both artificial (a ferrocene derivative) and natural (flavin nucleotides) mediators were studied as constituents of the charge-transfer process between the enzyme and the electrode. The comparative study of these biosensors, which were prepared in situ in a continuous flow system, made it possible to determine the advantages and disadvantages of each configuration when applied to flow-injection determination of cholesterol.


Subject(s)
Biosensing Techniques , Cholesterol/analysis , Electrochemistry , Electrodes , Sensitivity and Specificity
9.
Toxicon ; 38(6): 865-73, 2000 Jun.
Article in English | MEDLINE | ID: mdl-10695971

ABSTRACT

The hemorrhagic activity of Bothrops (B.) alternatus, B. ammodytoides, B. jararaca, B. jararacussu, B. moojeni and B. neuwiedii venoms from specimens captured in Argentina was assayed after i.d. injection to mice. The hemorrhagic haloes produced by each venom had different color intensities, although no significant differences were observed by measurement of the average diameters or the weight of the excised hemorrhagic haloes. Conversely, important differences were found by measuring the amount of hemoglobin extracted from excised hemorrhagic haloes of similar size produced by different venoms. The relationship between the amount of hemoglobin extracted and the weight of the excised hemorrhagic haloes was linear, with a slope (hemoglobin released per gram of hemorrhagic halo) characteristic for each venom, and proportional to the potency. On this basis, the activity of B. alternatus, B. ammodytoides and B. jararaca is similar, about 1.5 times higher than that of B. jararacussu and B. moojeni venoms and threefold higher than that of B. neuwiedii venom. Thus, measurement of the of hemoglobin released provides additional information in comparative studies, and may be used to assess the antihemorrhagic potency of antivenoms.


Subject(s)
Bothrops , Crotalid Venoms/toxicity , Hemorrhage/chemically induced , Animals , Crotalid Venoms/administration & dosage , Dose-Response Relationship, Drug , Hemoglobins/metabolism , Hemorrhage/blood , Injections, Intradermal , Mice , Peroxidases/blood
10.
Toxicon ; 38(1): 49-61, 2000 Jan.
Article in English | MEDLINE | ID: mdl-10669011

ABSTRACT

Bothrops ammodytoides, the smallest representative of this genus, is found only in Argentina. Venom was extracted from thirty adult specimens (35-70 cm in length, 90-300 g in weight) captured in the Province of Buenos Aires and kept in captivity. Venom yield was 3-30 mg. SDS-PAGE showed strong bands at 14.0; 23-25; 45; 54 and 63 kDa and weak bands at 17.0; 30.0; 40.0 and 85.0 kDa. Toxic activities were: LD50 (intravenous, mice) 0.5+/-0.2 microg/g; minimal procoagulant dose on human plasma (MPD-P) 35+/-2 mg/l; and minimal defibrinogenating dose (MDD, mice) 6-12 microg. Hemorrhagic and/or necrotic activities appear to play a major role in lethality; minimal hemorrhagic dose (MHD, mice) is 10+/-2 microg/g and minimal necrotizing dose (MND, mice) is 38+/-5 microg. The LD50, MPD-P and MND are among the lowest in venoms from Bothrops species found in Argentina. B. ammodytoides venom exhibited high proteolytic and phospholipase A2 activities. Most of the B. ammodytoides venom components cross-react with Bivalent Bothropic antivenom (Instituto Nacional de Producción de Biológicos ANLIS Dr. G. Malbrin, against B. alternatus and B. neuwiedii venoms). One ml of antivenom neutralizes 1.2 mg of B. ammodytoides venom.


Subject(s)
Bothrops/physiology , Crotalid Venoms/enzymology , Crotalid Venoms/toxicity , Animals , Antivenins/pharmacology , Blood Coagulation/drug effects , Blotting, Western , Chromatography, Gel , Electrophoresis, Polyacrylamide Gel , Enzyme-Linked Immunosorbent Assay , Erythrocytes/drug effects , Hemolysis/drug effects , Hemorrhage/chemically induced , Hemorrhage/pathology , Immunochemistry , Lethal Dose 50 , Mice , Muscle, Skeletal/pathology , Snake Bites/pathology
11.
J. venom. anim. toxins ; 6(2): 194-204, 2000. tab
Article in English | LILACS | ID: lil-276608

ABSTRACT

Blood samples of 50 healthy specimens from each of the following species: Bothrops alternatus, Bothrops jararacussu, Bothrops moojeni, and Bothrops neuwiedi diporus all kept in captivity were taken to determine the hematocrit (PCV) value, red blood cell count (RBC), total leukocyte (WBC) and differential leukocyte count, thrombocyte count, mean corpuscular volume (MCV), hemoglobin concentration (HbC), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC). These hematological parameters were compared to those obtained from other Bothrops species. PCV values, RBC, hemoglobin, WBC count, and differential leukocyte count are within the range of values reported for other Bothrops species, while the thrombocyte count was significantly lower. All the hematological parameters obtained from the four studied Bothrops species were higher than those described for B. ammodytoides.


Subject(s)
Animals , Male , Female , Rats , Bothrops/blood , Crotalus/blood , Hematologic Tests , Leukocyte Count , Platelet Count
12.
Analyst ; 124(3): 319-24, 1999 Mar.
Article in English | MEDLINE | ID: mdl-10605893

ABSTRACT

Three different glucose oxidase biosensors for the enzymatic determination of glucose, based on bilayer polymer coatings consisting of polypyrrole (PPy) and poly(o-phenylenediamine), were developed. The electrode substrates are Pt metal, carbon paste and an organic conducting salt (tetrathiafulvalene-tetracyanoquinodimethane), which introduces appreciable variability in the electrode construction process. The three sensors were compared with one another and with bare and PPy monolayer-coated sensors in terms of performance in the determination of glucose in a synthetic serum sample. These configurations provide improved selectivity against the interferences of electroactive species such as ascorbic acid and uric acid, frequently present in biological samples, and the differences between them can be taken advantage of in application to different kinds of samples.


Subject(s)
Blood Glucose/analysis , Biosensing Techniques , Blood Substitutes , Humans , Polymers
13.
Medicina (B Aires) ; 59(3): 238-42, 1999.
Article in Spanish | MEDLINE | ID: mdl-10451561

ABSTRACT

We have studied the immunochemical cross-reactivity and cross-neutralization of the lethal potency, hemorrhagic, necrotizing, procoagulant and (indirect) hemolytic activities of Bothrops jararacussu venom by the standard antivenoms produced in Argentina. These antivenoms are horse immunoglobulin F (ab')2 fragments from animals immunized with 1) Crotalus durissus terrificus venom (Monovalent Anticrotalic antivenom); 2) Bothrops alternatus and B. neuwiedii venoms (Bivalent Botropic antivenom); 3) B. alternatus, B. neuwiedii, B. jararaca and B. jararacussu venoms (Tetravalent Bothropic, or "Misiones" antivenom) and 4) B. alternatus, B. neuwiedii and C. d. terrificus venoms (Trivalent Botropic-Crotalic antivenom). In preincubation experiments, all the heterologous antivenoms neutralized the toxic and biological activities of B. jararacussu venom with a potency at least as high as the Tetravalent Botropic (i.e. the only homologous) antivenom, in which B. jararacussu venom was included as immunogen. These results suggest the possibility of using heterologous antibothropic antivenoms for the treatment of snake bites by B. jararacussu.


Subject(s)
Antivenins/therapeutic use , Bothrops , Crotalid Venoms/immunology , Snake Bites/therapy , Animals , Cross Reactions , Crotalid Venoms/administration & dosage , Neutralization Tests , Rats
14.
J. venom. anim. toxins ; 5(1): 67-83, 1999. ilus, tab, graf
Article in English | LILACS | ID: lil-290436

ABSTRACT

The immunochemical reactivity and neutralizing capacity of polyvalent Vipera antivenom (Vipera ammodytes, Vipera aspis, Vipera berus, Vipera lebetina, and Vipera xanthina) were tested on the enzymatic and biological activities of Crotalus durissus terrificus and the following Bothrops venoms from Argentina (Bothrops alternatus, Bothrops ammodytoides, Bothrops neuwiedii, Bothrops jararaca, Bothrops jararacussu, and Bothrops moojeni). The Vipera antivenom reacted weakly when tested by double immunoprecipitation (DIP) and reacted with all the venoms when tested by ELISA. Several components in all the venoms studied were recognized in Western blots. Vipera antivenom deactivated to different degrees in vitro procoagulant, (indirect) hemolytic, and proteolytic activities in all the venoms studied. Preincubation of Bothrops alternatus venom with Vipera antivenom neutralized a lethal potency of 4.5 LD50 in mice with an ED50 of 1.25 ñ 0.25 µl per µg of venom, and with 1.0 µl/µg inhibited 54 per cent of the hemorragic activity and 48 per cent of necrotic activity. Vipera antivenom (2.0 µl per µg toxin) inhibited the phospholipase A2 activity of purified crotoxin and decreased its lethal potency by 60 per cent, while the neutralizing capacity on the lethal potency of crude Crotalus durissus terrificus venom was poor even at a level of 5.0 µl/µg of venom.


Subject(s)
Animals , Rats , Antivenins/pharmacology , Antivenins/therapeutic use , Crotalus , Snake Bites/chemically induced , Crotalid Venoms/enzymology , Crotalid Venoms/pharmacology , Crotalid Venoms/toxicity , Argentina/epidemiology , Immunochemistry , Neutralization Tests
15.
Medicina [B Aires] ; 59(3): 238-42, 1999.
Article in Spanish | BINACIS | ID: bin-39968

ABSTRACT

We have studied the immunochemical cross-reactivity and cross-neutralization of the lethal potency, hemorrhagic, necrotizing, procoagulant and (indirect) hemolytic activities of Bothrops jararacussu venom by the standard antivenoms produced in Argentina. These antivenoms are horse immunoglobulin F (ab)2 fragments from animals immunized with 1) Crotalus durissus terrificus venom (Monovalent Anticrotalic antivenom); 2) Bothrops alternatus and B. neuwiedii venoms (Bivalent Botropic antivenom); 3) B. alternatus, B. neuwiedii, B. jararaca and B. jararacussu venoms (Tetravalent Bothropic, or [quot ]Misiones[quot ] antivenom) and 4) B. alternatus, B. neuwiedii and C. d. terrificus venoms (Trivalent Botropic-Crotalic antivenom). In preincubation experiments, all the heterologous antivenoms neutralized the toxic and biological activities of B. jararacussu venom with a potency at least as high as the Tetravalent Botropic (i.e. the only homologous) antivenom, in which B. jararacussu venom was included as immunogen. These results suggest the possibility of using heterologous antibothropic antivenoms for the treatment of snake bites by B. jararacussu.

16.
Toxicon ; 36(12): 1949-57, 1998 Dec.
Article in English | MEDLINE | ID: mdl-9839679

ABSTRACT

A study on the venom yield of snakes from Argentina over a three year period was carried out on adult specimens of Bothrops alternatus (n = 74); Bothrops neuwiedii (n = 127); Bothrops ammodytoides (n = 30); Bothrops moojeni (n = 14); Bothrops jararaca (n = 14); B. jararacussu (n = 6); Crotalus durissus terrificus (n = 120) and Micrurus spp. (n = 6) as well as with 12 specimens of newborn C. d. terrificus kept in captivity. While for each species there was a positive correlation between venom yield and number of snakes milked, the correlation with the snake's body weights after individual milkings was even better, suggesting that the size of the snakes is more important in determining the venom yield than the number of snakes milked or the specimen's sex. Individual milkings indicated that, in addition to the snake size, when the amount of venom is normalized per 100 g body weight there is a species specific difference in venom yield. It follows the order B. jararacussu > B. moojeni approximately = B. jararaca approximately = B. alternatus > B. neuwiedii> Micrurus spp approximately = B. ammodytoides> C. d. terrificus. Although the venom yield per 100 g body weight of newborn C. d. terrificus specimens is 2-fold higher than that of adults, no correlation was observed between venom yield and body weight.


Subject(s)
Snake Venoms/analysis , Snakes/physiology , Age Factors , Animals , Animals, Newborn , Argentina , Body Weight , Bothrops/physiology , Crotalid Venoms/analysis , Crotalus/physiology , Elapidae/physiology , Female , Male , Sex Factors
17.
Biosens Bioelectron ; 13(3-4): 371-82, 1998 Mar 01.
Article in English | MEDLINE | ID: mdl-9642772

ABSTRACT

The in situ potentiostatic electropolymerization of pyrrole (Py) on a Pt electrode in a thin-layer amperometric cell and the entrapment of the enzyme glucose oxidase (GOx) for the determination of glucose are reported. Polypyrrole (PPy) is directly formed by continuous passage of a buffered solution of the monomer (0.4 M) and enzyme (250 U mL-1) at pH 7 at a flow rate of 0.05-0.1 mL min-1 under a constant applied potential of +0.85 V vs Ag/AgCl decreases. The electrosynthesis of PPy by injection of 500 microL of a Py + GOx solution in a carrier electrolyte consisting of 0.05 M phosphate buffer and 0.1 M KCl at pH 7.0 was also assayed. The influence of the electropolymerization conditions on the analytical response of the sensor to glucose was investigated. The analytical performance of the PPy/GOx sensor was also studied in terms of durability and storage life, as well as selectivity against electroactive species such as ascorbic acid and uric acid as a function of the thickness of the polymer film formed.


Subject(s)
Electrochemistry , Flow Injection Analysis , Glucose Oxidase , Pyrroles/chemistry , Glucose/analysis , Polymers , Potentiometry , Sensitivity and Specificity
20.
Biochem Pharmacol ; 51(11): 1535-43, 1996 Jun 14.
Article in English | MEDLINE | ID: mdl-8630095

ABSTRACT

Crotoxin (CT), a phospholipase A2 (PLA2) derived from the venom of Crotalus durissus terrificus, is a heterodimeric protein composed of subunit B with enzymatic activity and a binding regulatory subunit (A) without enzyme activity. Although the PLA2 activity of CT may be important in its anti-proliferative activity, its cytostatic mechanism is unknown. In this study, we examined the cytostatic effect of PLA2-associated CT activity on squamous carcinoma cells expressing distinct levels of epidermal growth factor receptor (EGFr). CT was most effective in suppressing growth on cells expressing high intrinsic levels of EGFr. Cardiotoxin, another membrane active toxin with no intrinsic PLA2 activity, had no differential anti-proliferative activity on cells expressing high EGFr levels, suggesting a correlation between EGFr expression and CT-directed anti-proliferative activity. Both chemically modified CT (MCT) devoid of PLA2 activity and covalently cross-linked CT (CCT), which is functionally unable to utilize cellular membranes as PLA2 substrate, were also without growth inhibitory activity. No evidence for direct binding of CT to EGFr was found, although pretreatment with EGF was able to partially suppress the anti-proliferative activity of CT. Tyrosine phosphorylation of EGFr, however, was stimulated by CT in intact A431 cells. Tyrosine phosphorylation of EGFr was concentration-dependently stimulated (3- to 8-fold) in cellular membranes of A431 cells treated in vitro with CT but not with anti-proliferatively inactive MCT or CCT. The data provide evidence for transmembrane receptors involved in growth signaling (namely EGFr) as cellular targets and potential effectors of PLA2-mediated anti-proliferative activity of snake venom.


Subject(s)
Crotoxin/pharmacology , ErbB Receptors/drug effects , ErbB Receptors/physiology , Animals , Cell Division/drug effects , Crotoxin/metabolism , Epidermal Growth Factor/metabolism , ErbB Receptors/metabolism , Female , Humans , Phospholipases A/metabolism , Phospholipases A2 , Tumor Cells, Cultured , Uterine Cervical Neoplasms/drug therapy , Uterine Cervical Neoplasms/ultrastructure
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