Study of major genetic factors involved in pituitary tumorigenesis and their impact on clinical and biological characteristics of sporadic somatotropinomas and non-functioning pituitary adenomas.

Genetic and functional aberrations of guanine nucleotide-binding protein, alpha stimulating (GNAS), aryl hydrocarbon receptor interacting protein (AIP), and pituitary tumor transforming gene (PTTG) are among the most prominent events in pituitary tumorigenesis. A cohort of Brazilian patients with somatotropinomas (n=41) and non-functioning pituitary adenomas (NFPA, n=21) from a single tertiary-referral center were evaluated for GNAS and AIP mutations and gene expression of AIP and PTTG. Results were compared to the clinical and biological (Ki67 and p53 expression) characteristics of tumors and their response to therapy, if applicable. Genetic analysis revealed that 27% of somatotropinomas and 4.8% of NFPA harbored GNAS mutations (P=0.05). However, no differences were observed in clinical characteristics, tumor extension, response to somatostatin analog therapy, hormonal/surgical remission rates, Ki67 index, and p53 expression between mutated and non-mutated somatotropinomas patients. PTTG overexpression (RQ mean=10.6, min=4.39, max=11.9) and AIP underexpression (RQ mean=0.56, min=0.46-max=0.92) were found in virtually all cases without a statistically significant relationship with clinical and biological tumor features. No patients exhibited somatic or germline pathogenic AIP mutations. In conclusion, mutations in GNAS and abnormal PTTG and AIP expression had no impact on tumor features and treatment outcomes in this cohort. Our data support some previous studies and point to the need for further investigations, probably involving epigenetic and transcriptome analysis, to improve our understanding of pituitary tumor behavior.

Study of major genetic factors involved in pituitary tumorigenesis and their impact on clinical and biological characteristics of sporadic somatotropinomas and non-functioning pituitary adenomas

Genetic and functional aberrations of guanine nucleotide-binding protein, alpha stimulating (GNAS), aryl hydrocarbon receptor interacting protein (AIP), and pituitary tumor transforming gene (PTTG) are among the most prominent events in pituitary tumorigenesis. A cohort of Brazilian patients with somatotropinomas (n=41) and non-functioning pituitary adenomas (NFPA, n=21) from a single tertiary-referral center were evaluated for GNAS and AIP mutations and gene expression of AIP and PTTG. Results were compared to the clinical and biological (Ki67 and p53 expression) characteristics of tumors and their response to therapy, if applicable. Genetic analysis revealed that 27% of somatotropinomas and 4.8% of NFPA harbored GNAS mutations (P=0.05). However, no differences were observed in clinical characteristics, tumor extension, response to somatostatin analog therapy, hormonal/surgical remission rates, Ki67 index, and p53 expression between mutated and non-mutated somatotropinomas patients. PTTG overexpression (RQ mean=10.6, min=4.39, max=11.9) and AIP underexpression (RQ mean=0.56, min=0.46-max=0.92) were found in virtually all cases without a statistically significant relationship with clinical and biological tumor features. No patients exhibited somatic or germline pathogenic AIP mutations. In conclusion, mutations in GNAS and abnormal PTTG and AIP expression had no impact on tumor features and treatment outcomes in this cohort. Our data support some previous studies and point to the need for further investigations, probably involving epigenetic and transcriptome analysis, to improve our understanding of pituitary tumor behavior.

A novel coating concept for ileo-colonic drug targeting: proof of concept in humans using scintigraphy.

The in vivo proof of concept of a novel double-coating system, based on enteric polymers, which accelerated drug release in the ileo-colonic region, was investigated in humans. Prednisolone tablets were coated with a double-coating formulation by applying an inner layer composed of EUDRAGIT S neutralised to pH 8.0 and a buffer salt (10% KH2PO4), which was overcoated with layer of standard EUDRAGIT S organic solution. For comparison, a single coating system was produced by applying the same amount of EUDRAGIT S organic solution on the tablet cores. Dissolution tests on the tablets were carried out using USP II apparatus in 0.1N HCl for 2 h and subsequently in pH 7.4 Krebs bicarbonate buffer. For comparison, tablets were also tested under the USP method established for modified release mesalamine formulations. Ten fasted volunteers received the double-coated and single-coated tablets in a two-way crossover study. The formulations were radiolabelled and followed by gamma scintigraphy; the disintegration times and positions were recorded. There was no drug release from the single-coated or double-coated tablets in 0.1N HCl for 2h. The single-coated tablets showed slow release in subsequent Krebs bicarbonate buffer with a lag time of 120 min, while in contrast drug release from the double-coated tablets was initiated at 60 min. In contrast, using the USP dissolution method, normally employed for modified release mesalamine products, no discrimination was attained. The in vivo disintegration of the single-coated EUDRAGIT S tablets in the large intestine was erratic. Furthermore, in 2 volunteers, the single-coated tablet was voided intact. Double-coated tablets disintegrated in a more consistent way, mainly in the ileo-caecal junction or terminal ileum. The accelerated in vivo disintegration of the double-coating EUDRAGIT S system can overcome the limitations of conventional enteric coatings targeting the colon and avoid the pass-through of intact tablets. Moreover, Krebs bicarbonate buffer has the ability to discriminate between formulations designed to target the ileo-colonic region.

Levels of oxidative stress markers: correlation with hepatic function and worm burden patients with schistosomiasis.

Schistosomiasis is caused by Schistosoma mansoni and is a public health problem in Brazil. The typical granulomatous lesion is associated with the increase in the oxidative damage by generation of free radicals. The aim of this work was to correlate some oxidative stress markers with the worm burden on carriers of schistosomiasis (n = 30) in the acute phase in comparison to healthy subjects (n = 30). The pro-oxidant parameter used was the colorimetric quantification of reactive substances to thiobarbituric acid, while the antioxidant markers used were blood content of reduced glutathione and determination of the activity of catalase. The worm burden was assessed by Kato-Katz method. The results pointed out that initially there was no difference in the catalase activity. However, there was a positive correlation between the increase in parasitic load and intensity of lipid peroxidation, and decrease in the content of reduced glutathione. Additionally, only the aspartate aminotransferase levels presented to be high, while there was a decrease in bilirubin level. Therefore, a possible association between the establishment of the oxidative stress in tissue and the parasitic load of Schistosoma mansoni is suggested.

Pharmacokinetics of Tityus serrulatus scorpion venom determined by enzyme-linked immunosorbent assay in the rat.

Experiments were performed in two groups of anaesthetized rats to study the genesis of pulmonary oedema and to determine the pharmacokinetic parameters following a subcutaneous (s.c.) injection of Tityus serrulatus scorpion venom. In group I, the rats were anaesthetized with pentobarbital (4 mg/100 g, i.p.); the s.c. injection of scorpion venom at the dose of 50 micrograms/100 g did not induce arterial hypertension, but unilateral pulmonary oedema was observed in three of six rats. The injection of a higher dose of venom (200 micrograms/100 g, N = 6) induced arterial hypertension and bilateral (N = 3) or unilateral (N = 1) pulmonary oedema. These data indicate that it is possible to evoke unilateral pulmonary oedema without previous arterial hypertension induced by the venom. For the study of pharmacokinetic parameters a second group of six rats was anaesthetized with urethane (140 mg/ 100 g, i.p.) and the venom injected at a dose of 200 micrograms/100 g, s.c. The plasma concentrations of venom were determined by enzyme-linked immunosorbent assay, at times 0, 5, 30, 60, 180, 360, and 720 min after venom injection. A biphasic curve was obtained with an ascending phase followed by a descending phase. The maximum plasma scorpion venom concentration was reached at 60 min. The pharmacokinetic parameters showed a fast absorption rate (Ka = 0.058 min-1), a fast and high distribution of venom to tissues (t1/2 alpha = 31.50 min and Vdarea = 6800.47 ml.kg-1, respectively), a great affinity of the venom for the tissues (KCT = 0.056 min-1 and KTC = 0.002 min-1) and a slow elimination half-life (t1/2 beta = 173.25 min).

Thyroxin plasmal levels and sulfamethoxazol-Timetrhoprim total clearance in dogs

Os níveis plasmáticos de tiroxina (T4) foram determinados por radioimunoensaio em 9 cäes, antes da administraçäo, em dose única, via intramuscular ou intravenosa, de uma associaçäo (5:1) sulfametoxazol (SMT) - trimetropina (TMP), tendo a dose (30 mg/kg) sido calculada em relaçäo ao SMT. O clearance total (Clt) foi calculado para ambos os componentes da associaçäo após dosagem das concentraçöes sanguíneas, a intervalos regulares. Os níveis médios de T4 foram 1,01 mais ou menos 0,25 ug/dl, o Clt para o SMT e o TMP foram 1,38 mais ou menos 0,41 e 0,20 mais ou menos 0,04 l/kg/h respectivamente. Näo houve correlaçäo significativa entre os níveis de T4 e os valores de Clt para SMT ou para TMP

Estudos sobre os níveis sanguíneos de sulfametoxazol em caninos e ovinos: necessidade de adequaçäo do regime posológico / Sulphamethoxazol blood levels in dogs and sheep. Evidence for a differentiated dosage regimen

Os níveis sanguíenos de sulfametoxazol (SMT) foram determinados em caninos e ovinos, após administraçäo de produto comercial potencializado pela trimeoprina, em dose única de 30 mg/kg, por via intramuscular. Os níveis máximos alcançados foram: 6,52 mg/l em cäes, 4 h após a administraçäo, decaindo gradativamente até 24 h e 5,50 mg/l, em ovinos 2 h após a administraçäo, decaindo gradativamente até 12 h. A meia-vida biológica foi de 7,55 h para os caninos e 3,93 h, para os ovinos. O "clearance" total foi de 7,16 e 12,66 ml/min/kg, respectivamente no cäo e no carneiro. Cálculos adicionais mostraram que para se manter, nos ovinos, os mesmos níveis sanguíneos previstos para os caninos será necessário administrar dose 1,56 vezes maior ou diminuir o intervalo entre as administraçöes, nesta mesma proporçäo

Pharmacokinetic profile of tert-butylaminoethanethiol

A preliminary study of the pharmacokinetic parameters of t-Butylaminoethanethiol (TBAESH) was performed after administration of a single dose (35 mg/kg) either orally or intravenously. Plasma or blood samples were treated with dithiothreitol, perchloric acid and, after filtration, submitted to further purification with anionic resin. In the final step the drug was retained on a cationic resin column, eluted with NaCl lM and detected according to the method of Ellman (1958). The results suggested a pharmacokinetic behavior related to a one open compartment model with the following values for the total drug: area under the intravenous curve (AUC i.v.): 443(+ ou -) 24.0; AUC oral: 85.5(+ ou -) 14.5 ug min.ml(elevado a -1); elimination rate constant: 0.069(+ ou -) 0.0055 min(elevado a -1), biological half-life: 10.0(+ ou -) 0.80 min; distribution volume 1.15(+ ou -) 0.15 ml/g; biodisponibility: 0.19(+ ou -) 0.02. From a pharmacokinetic standpoint, TBAESH seems to have no advantage over the analogous disulfide compound

Pharmacokinetic profile of tert-butylaminoethanethiol.

A preliminary study of the pharmacokinetic parameters of t-Butylaminoethanethiol (TBAESH) was performed after administration of a single dose (35 mg/kg) either orally or intravenously. Plasma or blood samples were treated with dithiothreitol, perchloric acid and, after filtration, submitted to further purification with anionic resin. In the final step the drug was retained on a cationic resin column, eluted with NaCl lM and detected according to the method of Ellman (1958). The results suggested a pharmacokinetic behavior related to a one open compartment model with the following values for the total drug: area under the intravenous curve (AUCi.v.): 443 +/- 24.0; AUCoral: 85.5 +/- 14.5 micrograms min.ml-1; elimination rate constant: 0.069 +/- 0.0055 min-1, biological half-life: 10.0 +/- 0.80 min; distribution volume 1.15 +/- 0.15 ml/g; biodisponibility: 0.19 +/- 0.02. From a pharmacokinetic standpoint, TBAESH seems to have no advantage over the analogous disulfide compound.

Pharmacokinetic aspects of Tert-Butylaminoethyl disulfide, an experimental drug against schistosomiasis in mice

Um estudo preliminar da farmacocinética do t-butilamino-etil-dissulfeto foi conduzido utilizando droga fria ou radioativa em duas diferentes doses (35 e 300 mg/Kg). Amostras de plasma ou sangue foram tratadas com ditiotreiol, ácido perclórico, e, após filtraçäo, submetidas a uma subseqüente purificaçäo em um "batch" de resina aniônica. Na etapa final, a droga foi retida em coluna de resina catiônica, eluída com NaCl 1 M e detectada pelo método de Ellman (1958). Alternativamente, a droga radioativa foi detectada por cintilaçäo líquida. Os resultados correspondentes a droga total administrada na menor dose sugeriram um comportamento farmacocinético relacionado ao modelo de um compartimento aberto, com os seguintes parâmetros: área sob a curva intravenosa (ASCI.V.): 671 ñ 14; ASCoral: 150 ñ 40 microng.min.ml-1; constante de eliminaçäo: 0,07 min-1; meia-vida biológica: 9,8 min; volume de distribuiçäo: 0,74 ml/g. Para a dose mais alta, os resultados indicaram aparentemente a ocorrência de um modelo mais complexo e näo adequadamente classificado. Analisados em conjunto os resultados sugerem a ocorrência de um comportamento farmacocinético dose-dependente. A droga é absorvida e eliminada rapidamente, sendo este último processo relacionado principalmente a metabolizaçäo. A droga parece mais tóxica quando administrada via I.V. porque por esta via ela näo sobre metabolismo de primeira passagem e, é, por outro lado rapidamente distribuída para os tecidos. O nível sanguíneo máximo tolerado pelos animais parece ser de 16 microng/ml

Xylazine antinociception in mice: evidence for mediation by postsynaptic adrenoceptors.

The influence of 6-hydroxydopamine (6-OHDA) pretreatment on xylazine (XLZ)-induced antinociception was studied in mice using the writhing test (60 mg/kg acetic acid, ip, as the algogenic compound administered 10 min after 0.5 and 0.75 mg/kg XLZ, sc). 6-OHDA (100 mg kg-1 injection-1 administered ip on days 1, 3, 5, 7, 9 and 11 after birth) did not modify XLZ-induced antinociception, suggesting that this effect is mediated by postsynaptic alpha-2 adrenoceptors.

Pharmacokinetic aspects of tert-butylaminoethyl disulfide, an experimental drug against schistosomiasis in mice.

A preliminary study of the pharmacokinetic parameters of t-Butylaminoethyl disulfide was performed after administration of two different single doses (35 and 300 mg/kg) of either the cold or labelled drug. Plasma or blood samples were treated with dithiothreitol, perchloric acid, and, after filtration, submitted to further purification with anionic resin. In the final step, the drug was retained on a cationic resin column, eluted with NaCl 1M and detected according to the method of Ellman (1958). Alternatively, radioactive drug was detected by liquid scintillation counting. The results corresponding to the smaller dose of total drug suggested a pharmacokinetic behavior related to a one open compartment model with the following parameters: area under the intravenous curve (AUCi.v.): 671 +/- 14; AUCoral: 150 +/- 40 micrograms.min.ml-1; elimination rate constant: 0.071 min-1; biological half life: 9.8 min; distribution volume: 0.74 ml/g. For the higher dose, the results seemed to obey a more complex undetermined model. Combining the results, the occurrence of a dose-dependent pharmacokinetic behavior is suggested, the drug being rapidly absorbed and rapidly eliminated; the elimination process being related mainly to metabolization. The drug seems to be more toxic when administered I.V. because by this route it escapes first pass metabolism, while being quickly distributed to tissues. The maximum tolerated blood level seems to be around 16 micrograms/ml.

Xylazine antinociception in mice: evidence for mediation by postsynaptic adrenoceptors

The influence of 6-hydroxydopamine (6-OHDA) pretreatment on zylazine (XLZ)-induced antinociception was studied in mice using the writhing test (60 mg/Kg acetic acid, ip, as the algogenic compound administered 10 min after 0.5 0.75 mg/Kg XLZ, sc). 6-OHDA (100 mgKg-1 injection-1 administered ip on days 1, 3, 5, 7, 9 and 11 after bith) did not modify XLZ- induced antinociception, suggesting that effects is mediated by postsynaptic alpha-2 adrnoceptors

Effect of cocaine on xylazine analgesic activity.

The effect of cocaine on the antinociceptive action of xylazine (XLZ) was studied by the method of abdominal contortions in mice. While XLZ alone (0.5 mg/kg, sc) inhibited the contortions by 43%, cocaine (5 mg/kg, sc) produced 39% inhibition and combination of the two drugs reduced the contortions by 77%. Cocaine acted synergistically with XLZ, decreasing the ED50 from 0.42 to 0.13 mg/kg. The mechanism involved does not seem to be directly mediated by activation of alpha-2 receptors since pretreatment of the animals with yohimbine did not significantly influence the XLZ effect.

Further studies on the xylazine-yohimbine interaction.

A study of the Yohimbine-blocking action upon Xylazine-ability to inhibit the abdominal contortions elicited by an intraperitoneal injection of Acetic Acid (60 mg/kg) was carried out. Xylazine (0.75 mg/kg - subcutaneously) inhibited 44% of the abdominal contortions. Such an inhibition activity was reduced to a 19% level after a previous Yohimbine treatment (1 mg/kg - intramuscularly - 30 min before). The results suggested there is a 2.9 times reduction of Xylazine affinity for CNS alpha 2 receptors, and that the antagonism between the two drugs is of a competitive nature.