Antimicrobial effect of Dinoponera quadriceps (Hymenoptera: Formicidae) venom against Staphylococcus aureus strains.

AIMS: Dinoponera quadriceps venom (DqV) was examined to evaluate the antibacterial activity and its bactericidal action mechanism against Staphylococcus aureus. METHODS AND RESULTS: DqV was tested against a standard strain of methicillin-sensitive Staphylococcus aureus (MSSA), Staph. aureus ATCC 6538P and two standard strains of methicillin-resistant Staphylococcus aureus (MRSA), Staph. aureus ATCC 33591 and Staph. aureus CCBH 5330. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), the rate of kill and pH sensitivity of the DqV were determined by microdilution tests. Bactericidal and inhibitory concentrations of DqV were tested to check its action on Staph. aureus membrane permeability and cell morphology. The MIC and MBC of DqV were 6·25 and 12·5 µg ml(-1) for Staph. aureus ATCC 6538P, 12·5 and 50 µg ml(-1) for Staph. aureus CCBH 5330 and 100 and 100 µg ml(-1) for Staph. aureus ATCC 33591, respectively. Complete bacterial growth inhibition was observed after 4 h of incubation with the MBC of DqV. A lowest MIC was observed in alkaline pH. Alteration in membrane permeability was observed through the increase in crystal violet uptake, genetic material release and morphology in atomic force microscopy. CONCLUSIONS: The results suggest antibacterial activity of DqV against Staph. aureus and that the venom acts in the cell membrane. SIGNIFICANCE AND IMPACT OF THE STUDY: Alteration in membrane permeability may be associated with the antimicrobial activity of hymenopteran venoms.

Kidney injury molecule-1 and urinary gamma-glutamyl transferase as biomarkers of acute kidney injury in cats.

OBJECTIVES: To evaluate the concentration of kidney injury molecule-1 and activity of urinary gamma-glutamyl transferase in cats with urethral obstruction and healthy cats. MATERIALS AND METHODS: Blood and urine samples were collected from a group of 15 healthy cats (control group) and a group of 20 cats with urethral obstruction at presentation, and 24 hours and 7 days after unblocking the obstruction. The serum creatinine, urinary creatinine and urinary gamma-glutamyl transferase were measured by spectrophotometry and kidney injury molecule-1 by the sandwich enzyme-linked immunosorbent assay. RESULTS: On presentation, cats with obstruction had serum creatinine concentration and urinary gamma-glutamyl transferase index higher than healthy cats (mean difference 544 µmol/L, 95% confidence intervals 222 to 865 µmol/L, and 0.0022 U/µmol-uCre, 0.00043 to 0.0039 U/µmol-uCre, respectively), urine creatinine concentration lower (mean difference 25,624 µmol/L, 17,329 to 33,919 µmol/L), and no significant difference in the kidney injury molecule-1/urinary creatinine ratio (mean difference 13 pg/µmol-uCre, -33 to 59 pg/µmol-uCre). In the group of cats with urinary obstruction, over time serum creatinine decreased, urine creatinine increased, urinary gamma-glutamyl transferase index did not change significantly, and kidney injury molecule-1/urinary creatinine ratio increased. CLINICAL SIGNIFICANCE: Cats with post-renal obstruction and potential intrinsic renal damage had higher urinary gamma-glutamyl transferase index than healthy cats at the time of presentation and showed increase in kidney injury molecule-1/urinary creatinine ratio over time.

N-Methyl-(2S, 4R)-trans-4-hydroxy-L-proline, the major bioactive compound from Sideroxylon obtusifolium, attenuates pilocarpine-induced injury in cultured astrocytes.

Glial cells have been implicated in temporal lobe epilepsy in humans and in its models. Astrocytes are lost in several brain regions after acute seizures induced by pilocarpine and may suffer hyperplasia at subsequent time points. This study investigated the effect of N-methyl-(2S,4R)-trans-4-hydroxy-L-proline (NMP) on astrocytes exposed to cytotoxic concentrations of pilocarpine. Astrocytes were incubated with pilocarpine (half maximal inhibitory concentration (IC50)=31.86 mM) for 24 h. Afterwards, they were treated with NMP at concentrations ranging from 3.12 to 100 µg/mL for 24 h. Cell viability was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cytoplasmic reactive oxygen species (ROS) and mitochondrial transmembrane potential (ΔΨm) were analyzed by flow cytometry using 2',7'-dichlorofluorescein diacetate (DCFH-DA) and rhodamine-123 (Rho123), respectively. Expression of glial fibrillary acidic protein (GFAP) and voltage-dependent anion channel-1 (VDAC-1) were measured by western blot. Pilocarpine significantly decreased cell viability and mitochondrial potential and increased ROS concentration significantly by 6.7 times compared to the control. NMP concentrations ≥25 µg/mL protected astrocytes against pilocarpine-induced injury in a concentration-dependent manner. Concomitantly, NMP reduced cytoplasmic ROS accumulation to 27.3, 24.8, and 12.3% in the groups treated with 25, 50, and 100 µg/mL NMP, respectively. NMP also protected mitochondria from pilocarpine-induced depolarization. These effects were associated with improvement of pilocarpine-induced GFAP and VDAC-1 overexpression, which are important biomarkers of astrocyte dysfunction. In conclusion, the improvement of ROS accumulation, VDAC-1 overexpression, and mitochondrial depolarization are possible mechanisms of the NMP protective action on reactive astrocytes.

Molecular analysis of a mutant Anticarsia gemmatalis multiple nucleopolyhedrovirus (AgMNPV) shows an interruption of an inhibitor of apoptosis gene (iap-3) by a new class-II piggyBac-related insect transposon.

A new piggyBac-related transposable element (TE) was found in the genome of a mutant Anticarsia gemmatalis multiple nucleopolyhedrovirus interrupting an inhibitor of apoptosis gene. This mutant virus induces apoptosis upon infection of an Anticarsia gemmatalis cell line, but not in a Trichoplusia ni cell line. The sequence of the new TE (which was named IDT for iap disruptor transposon) has 2531 bp with two DNA sequences flanking a putative Transposase (Tpase) ORF of 1719 bp coding for a protein with 572 amino acids. These structural features are similar to the piggyBac TE, also reported for the first time in the genome of a baculovirus. We have also isolated variants of this new TE from different lepidopteran insect cells and compared their Tpase sequences.

Renal Alterations Induced by the Venom of Colombian Scorpion Centruroides Margaritatus.

BACKGROUND: Scorpion venom causes renal injury and affects vascular ion-channels function. Centruroides margaritatus scorpion is found in Colombia and is frequently the cause of envenomation accidents; however, its renal impact has never been investigated. OBJECTIVE: To evaluate the effects of C. margaritatus venom (CmV) on renal parameters using isolated rat kidney and renal cell culture models. METHODS: Wistar rats (n = 5, weighing 240-300 g) were first perfused with Krebs-Henseleit solution containing 6 g 100 mL-1 bovine serum albumin. After 30 minutes, the kidneys were perfused with CmV to a final concentration of 10 µgmL-1; evaluation was performed by measuring Perfusion Pressure (PP), Renal Vascular Resistance (RVR), Urinary Flow (UF), Glomerular Filtration Rate (GFR), and percentage of electrolyte tubular transport. Moreover, kidney histological analyses and cell cytotoxicity in renal tubule epithelial cells (MDCK) and proximal tubular cells (LLC-MK2) were assessed. RESULTS: CmV increased PP and RVR 60 min after perfusion. On the other hand, UF, GFR, and the percentages of sodium, potassium and chloride tubular transport decreased after experimental envenomation. UF dropped after 120 min, while GFR and percentage of electrolyte tubular transport diminished after 60, 90 and 120 min. CmV was not toxic to MDCK cell line but reduced the viability of LLC-MK2 cells at concentrations ranging from 6.25 to 200 µgmL-1. Histological analyses disclosed hydropic degeneration, edema, and protein deposits. Flow cytometry disclosed that cell death occurred predominantly by necrosis. CONCLUSION: Our results suggest that C. margaritatus venom can trigger renal impairment, mainly in the proximal kidney tubule.

Bothrops alternatus Snake Venom Induces Cytokine Expression and Oxidative Stress on Renal Function.

BACKGROUND: Envenomation caused by Bothrops alternatus is common in Southern Brazil. Acute Kidney Injury occurs after Bothrops snakebite and more information is necessaryrequired to understand its mechanism. OBJECTIVE: The objective was to evaluate the effect of Bothrops alternatus venom (BaV) on renal cells and rat isolated kidney function. METHODS: Wistar rats (n = 6, weighing 260-320 g) were perfused with a Krebs-Henseleit solution containing 6 g 100 mL-1 of bovine serum albumin. After 30 minutes, the kidneys were perfused with BaV to a final concentration of 1 and 3 µgmL-1; and subsequently were evaluated for Perfusion Pressure (PP), Renal Vascular Resistance (RVR), Urinary Flow (UF), Glomerular Filtration Rate (GFR), and percentage of electrolyte tubular transport. Renal histological analysis, cytokine release, oxidative stress and cytotoxicity in renal proximal tubular cells were assessed. RESULTS: BaV reduced PP, RVR, GFR, UF, total and proximal sodium transport (%TNa+), and chloride (%TCl-) in the isolated kidney perfusion model. Histological analysis of perfused kidneys disclosed the presence of proteinaceous material in the glomeruli and renal tubules, vacuolar tubular epithelial cell degeneration, Bowman's capsule degeneration, swelling of glomerular epithelial cells, glomerular atrophy and degeneration, and the presence of intratubular protein. Cytokine release (TNF-α, IL-1ß, IL-10) and oxidative stress were increased in the kidneys. The viability of LLC-MK2 cells (IC50: 221.3 µg/mL) was decreased by BaV and necrosis was involved in cell death. CONCLUSION: These findings indicate that BaV modifies functional parameters in an isolated perfused kidney model and has cytotoxic effects on renal lineage cells.

N-Methyl-(2S, 4R)-trans-4-hydroxy-L-proline, the major bioactive compound from Sideroxylon obtusifolium, attenuates pilocarpine-induced injury in cultured astrocytes

Glial cells have been implicated in temporal lobe epilepsy in humans and in its models. Astrocytes are lost in several brain regions after acute seizures induced by pilocarpine and may suffer hyperplasia at subsequent time points. This study investigated the effect of N-methyl-(2S,4R)-trans-4-hydroxy-L-proline (NMP) on astrocytes exposed to cytotoxic concentrations of pilocarpine. Astrocytes were incubated with pilocarpine (half maximal inhibitory concentration (IC50)=31.86 mM) for 24 h. Afterwards, they were treated with NMP at concentrations ranging from 3.12 to 100 μg/mL for 24 h. Cell viability was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cytoplasmic reactive oxygen species (ROS) and mitochondrial transmembrane potential (ΔΨm) were analyzed by flow cytometry using 2',7'-dichlorofluorescein diacetate (DCFH-DA) and rhodamine-123 (Rho123), respectively. Expression of glial fibrillary acidic protein (GFAP) and voltage-dependent anion channel-1 (VDAC-1) were measured by western blot. Pilocarpine significantly decreased cell viability and mitochondrial potential and increased ROS concentration significantly by 6.7 times compared to the control. NMP concentrations ≥25 µg/mL protected astrocytes against pilocarpine-induced injury in a concentration-dependent manner. Concomitantly, NMP reduced cytoplasmic ROS accumulation to 27.3, 24.8, and 12.3% in the groups treated with 25, 50, and 100 µg/mL NMP, respectively. NMP also protected mitochondria from pilocarpine-induced depolarization. These effects were associated with improvement of pilocarpine-induced GFAP and VDAC-1 overexpression, which are important biomarkers of astrocyte dysfunction. In conclusion, the improvement of ROS accumulation, VDAC-1 overexpression, and mitochondrial depolarization are possible mechanisms of the NMP protective action on reactive astrocytes.

Suitability of Corneal Tissue for Transplantation Derived From Violent Death: A 10-Year Analysis.

Trauma is a leading cause of death and disability worldwide. Corneal tissue donors generally are those who suffered an injury to the brain or fatal trauma caused by stroke, vehicle/motorbike accidents, gunshot wounds, and drowning or cardiovascular death. In Brazil, the Distrito Federal (DF) Eye Bank, located within a trauma center hospital, and the Secretariat of Public Security have collaborated with the aim of increasing the overall number of cornea donations from fatal trauma victims. The purpose of this study was to determine the suitability of cornea tissue for transplantation derived from trauma-related death. The records of eyes donated in the DF Eye Bank were analyzed retrospectively for the period from 2004-2013. We had 3388 cornea donors, the majority of which were between 21 and 30 years old (17.4%), which were derived from violent death (84.1%; P = .00) and were predominately male (73.5%). Among the donated corneas, 54.0% were used for optic purposes. Mechanical trauma caused by gunshot, stabbing or blunt force (23.7%), and road traffic injuries (11%) were the main causes of violent death. Another common cause of death was cardiovascular disease (26.3%). Donor tissue derived from violent death had no statistical interference on tissue suitability for transplantation (P = .06). Because of the large waiting lists, and waiting times for transplants, it is advisable to increase the available tissue from corneas donors derived from violent death through the implementation of this interagency model of collaboration and by the practicing of active tissue donor screening in trauma center hospitals.