Probenecid Sensitizes Neuroblastoma Cancer Stem Cells to Cisplatin.

We used both in vitro cultures of neuroblastoma cell lines and nude-mice xenotransplants to explore the effects of co-administration of cisplatin and probenecid. Probenecid sensitized neuroblastoma cells, including tumor cells with stem features, to the effects of cisplatin, both in vitro and in vivo. This effect was mediated by an increase in the apoptotic cell death and a concomitant decrease in cell proliferation. This effect is accompanied by modulation of the mRNA and protein of the drug efflux transporters MDR1, MRP2, and BCRP. The co-administration of probenecid with cisplatin should be explored as a possible therapeutic strategy.

Allopurinol reduces the lethality associated with acute renal failure induced by Crotalus durissus terrificus snake venom: comparison with probenecid.

BACKGROUND: Acute renal failure is one of the most serious complications of envenoming resulting from Crotalus durissus terrificus bites. This study evaluated the relevance of hyperuricemia and oxidative stress and the effects of allopurinol and probenecid in renal dysfunction caused by direct nephrotoxicity of C. d. terrificus venom. METHODOLOGY/PRINCIPAL FINDINGS: Hematocrit, protein, renal function and redox status were assessed in mice. High ratio of oxidized/reduced glutathione and hyperuricemia induced by C. d. terrificus venom were ameliorated by both, allopurinol or probenecid, but only allopurinol significantly reduced the lethality caused by C. d. terrificus venom. The effectiveness of probenecid is compromised probably because it promoted hypercreatinemia and hypocreatinuria and worsed the urinary hypo-osmolality in envenomed mice. In turn, the highest effectiveness of allopurinol might be due to its ability to diminish the intracellular formation of uric acid. CONCLUSIONS/SIGNIFICANCE: Data provide consistent evidences linking uric acid with the acute renal failure induced by C. d. terrificus venom, as well as that this envenoming in mice constitutes an attractive animal model suitable for studying the hyperuricemia and that the allopurinol deserves to be clinically evaluated as an approach complementary to anti-snake venom serotherapy.

Protective effect of L-kynurenine and probenecid on 6-hydroxydopamine-induced striatal toxicity in rats: implications of modulating kynurenate as a protective strategy.

The neuroactive metabolite at the kynunerine pathway, kynurenic acid (KYNA), is a well-known competitive antagonist at the co-agonist glycine site of the N-methyl-D-aspartate receptor (NMDAr), and also decreases the extracellular levels of glutamate by blocking α7-nicotinic acetylcholine receptor (α7-nAchr) located on glutamatergic terminals. KYNA has been often reported to be neuroprotective in different neurotoxic models. The systemic administration of L-kynurenine (L-KYN)--the precursor of KYNA--together with probenecid (PROB)--an inhibitor of organic acids transport--to rodents increases KYNA levels in the brain in a dose-dependent manner. The striatal infusion of the toxin 6-hydroxydopamine (6-OHDA) to rodents is one of the common models used to simulate Parkinson's disease (PD). Different studies have linked PD alterations with excessive glutamatergic transmission in the striatum since NMDAr antagonists exert beneficial effects in PD models. In this work we investigated the effect that a systemic administration of L-KYN+PROB exerted on the toxic model induced by 6-OHDA in rats. PROB (50 mg/kg, i.p.) + L-KYN (75 mg/kg, i.p.) were given to rats for seven consecutive days. On day two of treatment, the animals were infused with a single injection of 6-OHDA (20 µg/2 µl) into the right striatum. Fourteen days post-lesion, rotation behavior was assessed as a marker of motor impairment. The total levels of dopamine (DA) were also estimated in striatal tissue samples of 6-OHDA-treated animals as a neurochemical marker of damage. In addition, twenty eight days post-lesion, the striatal damage was assessed by hematoxylin/eosin staining and immunohistochemistry against glial fibrillary acidic protein (GFAP) in the same animals. Neurodegeneration was also assessed by Fluoro Jade staining. 6-OHDA infusion increased rotation behavior, striatal reactive gliosis and neurodegeneration, while DA levels were decreased. For all markers evaluated, we observed protective effects of L-KYN+PROB on the dopaminergic damage induced by 6-OHDA. Our results suggest that this strategy was useful to mitigate dopaminergic toxicity in the hemiparkinsonian model. The combined use of L-KYN and PROB is a valuable tool to modulate glutamatergic and cholinergic activities, presumably by means of increased levels of endogenous KYNA.

Protective effect of systemic L-kynurenine and probenecid administration on behavioural and morphological alterations induced by toxic soluble amyloid beta (25-35) in rat hippocampus.

Amyloid beta (Abeta) peptide exerts different toxic effects at a cellular level, including over-activation of N-methyl-D-aspartate receptor (NMDAr) and excitotoxicity, synaptic dysfunction and neuronal death. Kynurenic acid (KYNA) is an endogenous antagonist of NMDAr and alpha7 nicotinic receptors. Systemic administrations of both the immediate metabolic precursor of KYNA, L-kynurenine (L-KYN), and a proved inhibitor of KYNA's brain transport, probenecid (PROB), have shown to produce neuroprotective effects in a considerable number of experimental toxic conditions; however, this strategy has not been tested in the toxic model Abeta peptide so far. In this study we evaluated the effects of systemic administration of PROB (50 mg/kg/day for 7 days), L-KYN (75 mg/kg/day for 7 days) and their combination, on behavioural (locomotor activity and spatial memory) and morphological alterations induced by an intrahippocampal infusion of Abeta 25-35 to rats. An additional group was administered with the potent NMDAr antagonist dizocilpine (MK-801, 0.8 mg/kg/day for 7 days) for comparative purposes. A significant improvement of spatial memory was evident in Abeta-lesioned rats since post-lesion day 21 with all treatments tested and this effect was correlated with a reduction of cell damage and a decrease in reactive gliosis in hippocampal CA1 area. Neither L-KYN, nor PROB, or their combination, produced major alterations in motor function when given alone to rats. These results suggest that modulation of NMDAr activity by mean of therapeutic strategies designed to enhance KYNA in the brain may help to counteract neurodegenerative events coursing with Abeta toxicity and excitotoxic patterns.

Abdome agudo em ginecologia / Acute abdomen in gyncology

O objetivo deste trabalho é revisar as três principais causas do abdome agudo em ginecologia que säo a doença inflamatória pélvica, prenhez ectópica e a torçäo anexial, abordando aspectos epidemiológicos, diagnósticos e terapêuticos

Gonorrhea in preschool- and school-aged children. Report of the prepubertal gonorrhea cooperative study group.

Single-dose antibiotic therapy was evaluated in 108 episodes of culture-confirmed, uncomplicated gonorrhea in 100 prepubertal children. There were 15 boys and 85 girls between 14 months and 14 years of age. Penicillin G procaine, 100,000 units/kg intramuscularly, was compared with amoxicillin trihydrate, 50 mg/kg orally. Probenecid, 25 mg/kg, was given simultaneously. Both drugs provided prompt bacteriological and clinical response. Multiple episodes of gonorrhea, presumably caused by reexposure, occurred in six girls. Oral and anal cultures were negative in all of 47 Costa Rican cases but were commonly positive in US children. Anal cultures yielded gonococci in 52% of girls and 25% of boys, and oral cultures were positive in 18% and 13%, respectively. In three instances, rectal cultures confirmed the diagnosis when vaginal cultures were negative. Gonorrhea should be considered in every child with vaginal or urethral discharge. Single-dose penicillin-probenecid or amoxicillin-probenecid treatment is curative.