Paulo Sergio Ferreira Barbosa

Renal toxicity of Bothrops moojeni snake venom and its main myotoxins.

Acute renal failure is one the most common systemic complications after snakebite, however, its pathogenesis remains obscure. In this study we evaluated the renal effects of Bothrops moojeni venom and its myotoxins (Bmtx-I and BmtxII) in rat isolated perfused kidneys. The myotoxins were purified by ion-exchange chromatography and reverse phase HPLC. The whole venom (10 microg/ml) and myotoxins (5 microg/ml) were added to the perfusion system 30 min after the beginning of each perfusion. The renal effects were compared to a control group perfused with modified Krebs-Henseleit solution alone. B. moojeni venom decreased the perfusion pressure (PP), renal vascular resistance (RVR), and the percent sodium, potassium and chloride tubular transport (%TNa(+), %TK(+), %TCl(-)). In contrast, the venom increased the urinary flow (UF), glomerular filtration rate (GFR), and the sodium, potassium and chloride excretion (ENa(+), EK(+), ECl(-)). The renal effects of myotoxin I was very similar to those of the whole venom, but there was an increase rather than a decrease in the PP and RVR. Myotoxin II had no effect on renal physiology, except for a transient decrease in %TK(+). In conclusion, B. moojeni venom caused intense alterations in renal physiology, including a drop in vascular resistance associated with diuresis, natriuresis and kaliuresis. Bmtx-I had an opposite effect when compared to whole venom, showed in the parameters of PP and RVR. Bmtx-II had a mild effect in %TK(+). The apparent inability of Bmtx-II to induce the renal effect similarly to Bmtx-I should be explained by the absence in the Bmtx-II of the C-terminal lysine rich region.

Purification and characterization of the biological effects of phospholipase A2 from sea anemone Bunodosoma caissarum

Sea anemones contain a variety of biologically active substances. Bunodosoma caissarum is a sea anemone from the Cnidaria phylum, found only in Brazilian coastal waters. The aim of the present work was to study the biological effects of PLA(2) isolated from the sea anemone B. caissarum on the isolated perfused kidney, the arteriolar mesenteric bed and on insulin secretion. Specimens of B. caissarum were collected from the São Vicente Channel on the southern coast of the State of São Paulo, Brazil. Reverse phase HPLC analysis of the crude extract of B. caissarum detected three PLA(2) proteins (named BcPLA(2)1, BcPLA(2)2 and BcPLA(2)3) found to be active in B. caissarum extracts. MALDI-TOF mass spectrometry of BcPLA(2)1 showed one main peak at 14.7 kDa. The N-terminal amino acid sequence of BcPLA(2)1 showed high amino acid sequence identity with PLA(2) group III protein isolated from the Mexican lizard (PA23 HELSU, HELSU, PA22 HELSU) and with the honey bee Apis mellifera (PLA(2) and 1POC_A). In addition, BcPLA(2)1 also showed significant overall homology to bee PLA(2). The enzymatic activity induced by native BcPLA(2)1 (20 microg/well) was reduced by chemical treatment with p-bromophenacyl bromide (p-BPB) and with morin. BcPLA(2)1 strongly induced insulin secretion in presence of high glucose concentration. In isolated kidney, the PLA(2) from B. caissarum increased the perfusion pressure, renal vascular resistance, urinary flow, glomerular filtration rate, and sodium, potassium and chloride levels of excretion. BcPLA(2)1, however, did not increase the perfusion pressure on the mesenteric vascular bed. In conclusion, PLA(2), a group III phospholipase isolated from the sea anemone B. caissarum, exerted effects on renal function and induced insulin secretion in conditions of high glucose concentration.

Effects of Thalassophryne nattereri fish venom in isolated perfused rat kidney.

Thalassophryne nattereri, popularly known as Niquim, is a venomous fish responsible for many accidents in fishermen in the Northeast of Brazil. The effects of T. nattereri venom on renal physiology has not been tested. Isolated kidneys from Wistar rats of 240-280 g weight were perfused with Krebs-Henseleit solution containing 6g% of previously dialyzed bovine serum albumin. The effects of Niquim venom were studied on the perfusion pressure (PP), renal vascular resistance (RVR), urinary flow (UF), glomerular filtration rate (GFR), percent of sodium tubular transport (%TNa(+)), percent of potassium tubular transport (%TK(+)) and percent of chloride tubular transport (%TCl(-)). The venom of T. nattereri (0.3, 1.0, and 3.0 microg/ml) was always added to the system 30 minutes after the beginning of each experiment (n=6). All experiments were preceded by 30 minutes internal control period and an external control group, where kidneys were perfused with only Krebs-Henseleit solution. All three doses tested promoted increases in PP and RVR. The first two doses also increased GFR and UF. The higher dose promoted decreases in GFR, UF, %TNa(+), %TK(+), %TCl(-). In the treated groups we observed hyalin casts inside all tubules and proteinaceous material in the urinary space. We conclude that the effects resulted from niquim venom agents that promoted a direct effect in kidney cells causing the release of vasoactive factors.

Renal Alterations Promoted By The Lectins From Canavalia Ensiformis (Cona) And Dioclea Guianensis (Dguil) Seeds

The lectin from the seeds of Canavalia ensiformis (ConA) and Dioclea guianensis (DguiL) was tested upon its renal effects using the isolated perfusion rat kidney method. Both lectins (10 microg/ml) affected perfusion pressure and renal vascular resistance, but DguiL showed a much greater action than ConA. However, ConA, but not DguiL, affected potassium tubular transport.

Purification and biological effects of a C-type lectin isolated from Bothrops moojeni

Snake venom proteins from the C-type lectin family have very distinct biological activities despite their highly conserved primary structure, which is homologous to the carbohydrate recognition region of true C-type lectins. We purified a lectin-like protein (BmLec) from Bothrops moojeni venom and investigated its effect on platelet aggregation, insulin secretion, antibacterial activity, and isolated kidney cells. The BmLec was purified using two chromatographic steps: affinity chromatography and reverse phase high performance liquid chromatography (HPLC). BmLec showed a dose-dependent platelet aggregation and significantly decreased the bacterial growth rate in approximately 15%. During scanning electron microscopy, the profile of Xanthomonas axonopodis pv. passiflorae treated with lectin disclosed a high vesiculation and membrane rupture. BmLec induced a strong and significant increase in insulin secretion at 2.8 and 16.7 mM glucose concentrations, and this effect was seen in the presence of EGTA in both experiments. BmLec (10 µg/mL) increased the perfusion pressure, renal vascular resistance and urinary flow. The glomerular filtration rate and percentages of sodium, potassium and chloride tubular transport were reduced at 60 minutes of perfusion. Renal alterations caused by BmLec were completely inhibited by indomethacin in all evaluated parameters. In conclusion, the C-type lectin isolated from Bothrops moojeni affected platelet aggregation, insulin secretion, antibacterial activity and isolated kidney function.

Epidemiologia dos acidentes por Thalassophryne nattereri (niquim) no Estado do Ceará (1992-2002)

In Ceará State (1992 to 2002) 16 cases of envenomation by Thalassophryne nattereri occurred in the seaside of Ceará, 87.5% of cases in the region of Fortaleza and 12.5% in the interior of Ceará State. Ninety four percent were men and 6% women. Age range: 75% between 21 and 40 years and 19% between 41 and 60 years old. The time between medical assistance and the accident varied from 1 to 5 hours (4 cases), 6 to 12 hours (3 cases), over 12 hours in 4 cases and 5 patients did not know. Clinical manifestations observed were pain, local edema, transitory ischemia, paresthesia, ecchymosis and burned skin sensation. Anti inflammatory and analgesic drugs were used. In some cases, anesthetic, hot water, surgical peeling and anti-histaminic drugs were used. In 75% of cases cure was confirmed and in 12% cure was not confirmed. The number of accidents is probably higher than was found due to subnotification.

Renal Effects Of The Lectin From Canavalia Brasiliensis Seeds

The lectin from the seeds of Canavalia brasiliensis (Con Br) was tested for its renal effects using the isolated perfusion rat kidney method. Three different doses were examined (3,10 and 30 microgram / ml), which were compared with a control group. The control group was perfused with only Krebs-Henseleit solution containing 6 percent BSA. Con Br caused diuresis and natriuresis, with a mild alteration on the perfusion pressure. Probably the lectin is inhibiting the Na+ / K+ / 2Cl- transporter present in the thick ascending limb of the Henle´s loop.

Renal effects induced by the lectin from Vatairea macrocarpa seeds

Lectins are glycoproteins that interact reversibly and specifically with carbohydrates. The renal effects of the galactose‐binding lectin from the seeds of Vatairea macrocarpa were investigated. Isolated kidneys from Wistar rats (240–280 g) were perfused with Krebs‐Henseleit solution containing 6% bovine serum albumin. The V. macrocarpa lectin (10 μg mL−1) increased the perfusion pressure, renal vascular resistance, urinary flow and glomerular filtration rate. However, V. macrocarpa lectin did not change the percentage sodium, potassium or chloride tubular transport. Pretreatment with lectin‐galactose complex significantly blocked the increase in perfusion pressure, renal vascular resistance, urinary flow and glomerular filtration rate. The control group showed a small amount of a proteinaceous material in the urinary space, although no alteration in the renal tubules was detected. The administration of galactose alone did not modify the functional parameters of the kidney. Kidneys perfused with V. macrocarpa lectin showed moderate deposits of a proteinaceous material in the tubules and urinary space. Those pre‐treated with lectin‐galactose complex had only small amount of a proteinaceous material in the urinary space. No abnormalities were seen in renal tubules. The results suggest that lectin from V. macrocarpa seeds has important effects on the carbohydrate‐binding sites of the renal system, given the reversal of renal effects with the use of that specific inhibitor.

Antivenom action on renal effects induced by Thalassophryne nattereri venom

Thalassophryne nattereri (niquim) is a venomous fish responsible for numerous accidents involving fishermen in northern and northeastern Brazil. The aim of the present investigation was to evaluate the action of antivenom on renal effects caused by Thalassophryne nattereri venom. Isolated kidneys of Wistar rats were perfused with a previously dialyzed Krebs-Henseleit solution containing 6 g% bovine serum albumin. The antivenom action was studied through perfusion pressure (PP), renal vascular resistance (RVR), urinary flow (UF) and glomerular filtration rate (GFR). The niquim venom (1 µg/mL), the antivenom alone (1 µg/mL) or the venom incubated with antivenom were added to the system 30 minutes after the beginning of each perfusion. Previous works have shown venom induced-alterations of renal function parameters. In the isolated rat kidney, T. nattereri venom (1 µg/mL) increased the perfusion pressure and renal vascular resistance at 60, 90 and 120 minutes. UF and GFR also increased at 60, 90 and 120 minutes when compared with the control group; however, no effects were observed on the percent of sodium (%TNa+control = 81.1 ±0.86; %TNa+60 = 78.04 ±1.18; %TNa+90 = 76.16 ±3.34; %TNa+120 = 79.49 ±0.87) and potassium (%TK+control = 72.29 ±1.12; %TK+60 = 75.41 ±0.65; %TK+90 = 71.23 ±2.55; %TK+120 = 76.62 ±1.04) tubular transport. The administration of the antivenom (1 µg/mL) incubated with venom (1 µg/mL) reduced the changes in PP, RVR, UF and GFR provoked by Thalassophryne nattereri venom. The group perfused with venom alone showed a moderate deposit of a proteinaceous material in the tubules and urinary space. The group perfused with the antivenom presented similar results to the control group. In conclusion, the antivenom was able to decrease the effects induced by T. nattereri venom in isolated rat kidney.

The effect of Cratylia floribunda lectin on renal hemodynamics and ion transport

As lectinas sao descritas como (glico)proteinas que se ligam, especificamente e reversivelmente, a carboidratos. Lectinas de leguminosas isoladas da subtribo Diocleinae (Canavalia, Dioclea eCratylia) sao estruturalmente homologas em relacao as suas estruturas primarias. Demonstrou-se que as lectinas de DiocleinaeCanavalia brasiliensis, Dioclea guianensis eCanavalia ensiformis alteram diferentemente parâmetros fisiologicos em rins isolados de ratos. Dessa maneira, o objetivo deste estudo foi investigar o papel da lectina de Cratylia floribunda (CFL) na hemodinâmica renal e no transporte de ions em ratos. Em rins isolados perfundidos, CFL (10 mg/mL, n=5) aumentou a pressao de perfusao renal, a resistencia vascular renal e reduziu o percentual do transporte tubular de K+, mas nao alterou o fluxo urinario, a taxa de filtracao glomerular e o percentual de transporte tubular dos ions sodio e cloreto. No leito mesenterico isolado perfundido, CFL (3 e 10 mg/mL/min, n=4) nao alterou o tonus basal ou a contracao do tecido induzida por fenilefrina (1 mM/mL/min). Em conclusao, a lectina de sementes de Cratylia floribunda altera parâmetros hemodinâmicos renais, provavelmente de origem tubular, e nao por alteracoes hemodinâmicas.