Molecular mechanism of action and pharmacokinetic properties of methotrexate.

Since its discovery in 1945, methotrexate has become a standard therapy for number of diseases, including oncological, inflammatory and pulmonary ones. Major physiological interactions of methotrexate include folate pathway, adenosine, prostaglandins, leukotrienes and cytokines. Methotrexate is used in treatment of pulmonary sarcoidosis as a second line therapy and is drug of choice in patients who are not candidates for corticosteroid therapy, with recommended starting weekly dose of 5-15 mg. Number of studies dealt with methotrexate use in rheumatoid arthritis and oncological patients. Authors are conducting research on oral methotrexate use and pharmacokinetics in chronic sarcoidosis patients and have performed literature research to better understand molecular mechanisms of methotrexate action as well as high level pharmacokinetic considerations. Polyglutamation of methotrexate affects its pharmacokinetic and pharmacodynamic properties and prolongs its effect. Bile excretion plays significant role due to extensive enterohepatic recirculation, although majority of methotrexate is excreted through urine. Better understanding of its pharmacokinetic properties in sarcoidosis patients warrant optimizing therapy when corticosteroids are contraindicated in these patients.

Differential response of antioxidative systems of maize (Zea mays L.) roots cell walls to osmotic and heavy metal stress.

An analysis of peroxidase and ascorbate oxidase activity, phenolic content and antioxidant capacity of isolated maize root cell walls was performed in controls and plants stressed with polyethylene glycol (PEG) or heavy metals, zinc or copper. Peroxidase activity (oxidative and peroxidative) was more pronounced in the ionic than in the covalent cell wall fraction. PEG induced an increase and Zn(2+) a decrease of both ionically bound peroxidase activities. In the covalent fraction, Cu(2+) decreased oxidative and increased peroxidative activity of peroxidase. Isoelectric focusing of ionically bound proteins and activity staining for peroxidase demonstrated increased intensities and appearance of new acidic isoforms, especially in Zn(2+) and PEG treatments. Most pronounced basic isoforms (pI ~ 7.5) in controls, decreased in intensity or completely disappeared in stressed plants. Ascorbate oxidase activity was significantly increased by PEG and decreased by Zn(2+) treatments, and highly correlated with peroxidase activity. Antioxidant capacity and total phenolics content increased in heavy metal-treated and decreased in PEG-treated plants. Analysis of individual phenolic components revealed p-coumaric and ferulic acids, as the most abundant, as well as ferulic acid dimers, trimers and tetramers in the cell walls; their quantity increased under stress conditions. Results presented demonstrate the existence of diverse mechanisms of plant response to different stresses.

Characterisation of phenol oxidase and peroxidase from maize silk.

Silk of some maize genotypes contains a high level of phenolics that undergo enzymatic oxidation to form quinones, which condense among themselves or with proteins to form brown pigments. Two phenolic oxidizing enzymes, peroxidase (POD; EC 1.11.1.7) and polyphenol oxidase (PPO; EC 1.10.3.1), from maize (Zea mays L.) silk were characterised with respect to their preferred substrate, different isoforms and specific effectors. One browning silk sample with high, and two non-browning samples with low phenolic content were investigated. Although POD oxidizes a wide range of phenolic substrates in vitro, its activity rate was independent of silk phenolic content. PPO activity, detected with o-diphenolic substrates, was abundant only in browning silk, and low or absent in non-browning silk. Pollination increased POD but not PPO activity. Isoelectric-focusing (IEF) and specific staining for POD and PPO showed a high degree of polymorphism that varied with silk origin. The IEF pattern of POD revealed a number of anionic and several cationic isoenzymes, with the most pronounced having neutral pI 7 and a basic isoform with pI 10. Detected isoforms of PPO were anionic, except for one neutral form found only in browning silk, and occupied positions different from those of POD. Different inhibitory effects of NaN(3), EDTA, KCN, and L-cysteine, as well as different impacts of a variety of cations on the oxidation of chlorogenic acid, mediated by PPO or POD, were detected. The findings are discussed in terms of a possible roles of these enzymes in defence and pollination.

Anti-tumor effect of Coriolus versicolor methanol extract against mouse B16 melanoma cells: in vitro and in vivo study.

Numerous studies have shown immunostimulatory and anti-tumor effects of water and standardized aqueous ethanol extracts derived from the medicinal mushroom, Coriolus versicolor, but the biological activity of methanol extracts has not been examined so far. In the present study we investigated the anti-tumor effect of C. versicolor methanol extract (which contains terpenoids and polyphenols) on B16 mouse melanoma cells both in vitro and in vivo. In vitro treatment of the cells with the methanol extract (25-1600 microg/ml) reduced melanoma cell viability in a dose-dependent manner. Furthermore, in the presence of the methanol extract (200 microg/ml, concentration IC(50)) the proliferation of B16 cells was arrested in the G(0)/G(1) phase of the cell cycle, followed by both apoptotic and secondary necrotic cell death. In vivo methanol extract treatment (i.p. 50 mg/kg, for 14 days) inhibited tumor growth in C57BL/6 mice inoculated with syngeneic B16 tumor cells. Moreover, peritoneal macrophages collected 21 days after tumor implantation from methanol extract-treated animals exerted stronger tumoristatic activity ex vivo than macrophages from control melanoma-bearing mice. Taken together, our results demonstrate that C. versicolor methanol extract exerts pronounced anti-melanoma activity, both directly through antiproliferative and cytotoxic effects on tumor cells and indirectly through promotion of macrophage anti-tumor activity.

Hybrid PLtl promoter with dual regulation control.

The newly constructed PLtl hybrid promoter is composed of the operator and promoter sequences of tac and the -35 to -135 region of the phage lambda PL promoter, which contains the AT-rich block and the OL2 and OL3 segments. Transcriptional properties of PLtl were examined and compared with tac and lambda PL as reference promoters. The hybrid PLtl exhibits different and improved properties over tac promoter in four ways: (i) when repressed, the repression is almost complete; (ii) after complete induction, the hybrid PLtl promoter shows a 1.4-2 times higher expression; (iii) the hybrid PLtl promoter permits flexible gene expression because it can be utilized under either or both repression controls simultaneously; (iv) the PLtl promoter permits enhanced expression of genes encoding products with unknown properties. When compared with the strong promoter PL from phage lambda, results with the PLtl promoter in lacZ fusion constructs show higher levels of beta-galactosidase activity. We also constructed a plasmid vector, pPLtl7G, which contains the hybrid PLtl promoter with a polylinker sequence at its 3' end, which facilitates efficient fusions of foreign genes in any of the reading frame.

[Viscerosynthesis--use of mechanical sutures in digestive tract surgery]. / Viscerosinteza--primjena mehanickog sava u digestivnoj kirurgiji.

Mechanical suture (stapler) was applied 164 times in digestive surgery in the period from October 1985 to December 1988. There have been performed 82 anastomoses (30 low collateral, 20 esophagointestinal, 20 ileocolic, 10 enteroenteral and 2 colocolic) and 76 closure of intestines. Anastomoses were performed with EEA stapler in 50, GIA stapler in 30 and TA stapler in 2 cases. Intraoperative complications related to the use of stapler were observed in 4.8% cases. Clinically manifested dehiscence of the stapler anastomoses was evident in 4.8% (82) and immediate cause of death in 1.2% (1) case. The incidence of secondary wound infection after four years was 2.4%. No clinically manifested stenosis of anastomoses were observed within the follow up period from one to four years.

[Low anterior resection of the rectum with the linear and circular stapler in the treatment of carcinoma of the middle third of the rectum]. / Niska prednja resekcija rektuma s linearnim i cirkularnim samosivacem u lijecenju karcinoma srednje trecine rektuma.

Low anterior resection by linear (TA 55) and circular (EEA) stapler was done in eighteen patients with adenocarcinoma of the middle third of the rectum. One patient died of lung embolism after having underwent the surgery. The stercoral fistula was clinically and radiologically proven in only one of the surgically treated patients and it healed without medicament therapy. The protective proximal colostomy was not performed. Late functional results were satisfactory and none of the patients developed stenosis of the anastomosis. Two operated patients (Dukes' C) relapsed 12 and 18 months after the surgery.

[Agenesis of the gallbladder -- case report and a short review of the literature]. / Agnezija jucnog mjehura -- prikaz bolesnika i kratak pregled literature.

Agenesis of the gallbladder is a rare anomaly of the biliary system. Only 200 cases have thus far been reported in the world medical references. The authors have presented a case with a congenitally absent gallbladder and cystic duct. The diagnosis was made exclusively with peroperative cholangiography, because preoperative radiologic attempts mimics an obstructed cystic duct. The incidence of congenital absence of the gallbladder and cystic duct is between 0.01 and 0.015%. The case presented here was operated on with a preoperative diagnosis of an obstructed cystic duct. The agenesis was verified during surgery using peroperative radiomanometry and cholangiography. The importance of this anomaly lies in its recognition because it can be accompanied by choledocholithiasis. In as much as choledocholithiasis is coexistant it must be treated with the standard surgical procedures.