Localization and measurement of extracellular plant galactosidases

A simple, rapid and sensitive procedure for the identification and determination of plant extracellular alpha-galactosidase and beta-galactosidase is described using callus cultures and seedlings from tomato. Synthetic substrates (1-naphthyl- and p-nitrophenyl-alpha-D- and beta-D-galactopyranosides) were used for the identification and determination of intracellular and extracellular activity of alpha-galactosidase and beta-galactosidase, respectively. Many iminosugars or azasugars are strong glycosidase inhibitors and some of them show promising chemotherapeutic effects against viral diseases, and are potentially antidiabetic agents, as well as antitumor agents. These facts initiated our interest in a rapid and sensitive assay to determine activity of alpha-galactosidase and beta-galactosidase in plant tissues. The results presented here show the potential of the assay of the activity of intracellular and extracellular galactosidases of plant origin in inhibitory and/or biotechnological studies.     

Laser surgery for the treatment of glottic carcinomas

PURPOSE: The standard treatment for patients with early glottic carcinoma in Israel has been radiotherapy. In recent years, encouraging results with laryngo-microscopic carbon dioxide laser surgery as a treatment for early glottic carcinoma has changed our treatment strategy. We conducted a retrospective study to investigate the results of carbon dioxide laser excisional technique for early glottic carcinoma (T1, T2). MATERIALS AND METHODS: Twenty-six had squamous cell carcinoma (SCC), (21 patients with T1 and 5 patients with T2 lesions), 3 had carcinoma in situ, (CIS) and 3 had verrucous carcinoma (VC). RESULTS: All patients were free of disease after salvage treatment at the most recent follow-up. CONCLUSIONS: Careful patient selection with endoscopic staging and strict follow-up are essential to secure good results in the treatment of carbon dioxide laser for early laryngeal carcinoma.     

Toluene diisocyanate colocalizes with tubulin on cilia of differentiated human airway epithelial cells.

Toluene diisocyanate (TDI), a highly reactive industrial chemical with widespread use in the manufacture of polyurethane and plastics, is the leading cause of occupational asthma associated with chemical exposure. We report the effects of TDI vapor (20, 100, 500, 1000 ppb) in vitro on differentiated human bronchial epithelial cells. Increased mucus was observed by electron microscopy at all TDI concentrations. Cytotoxicity, as evidenced by cell pyknosis and DNA fragmentation, was detected following a 30-min exposure to TDI concentrations of 100 ppb or higher. At 1000 ppb, transepithelial resistance was lost. Using confocal microscopy and double staining, TDI was found colocalized with ciliary tubulin in cultures that had been exposed to 20 and 100 ppb. These findings are the first to identify TDI binding to human pulmonary epithelial cells and indicate extensive binding to the cilia of differentiated epithelial cells. The in vivo implications of these findings include decreased ciliary movement and longer retention of TDI and hence increased exposure. Altered cytoskeletal-derived signal transduction may be a consequence of tubulin involvement. The effects of such changes on respiratory sensitization remain to be explored.     

Intracellular S-glutathionyl adducts in murine lung and human bronchoepithelial cells after exposure to diisocyanatotoluene.

Diisocyanatotoluene (toluene diisocyanate, TDI), a 4:1 mixture of 2, 4- and 2,6-isomers used in the preparation of polyurethanes, causes occupational asthma by an as yet unknown mechanism. We previously showed that it forms adducts with the apical surface of the bronchoepithelium in vivo, and with ciliary microtubules in cultured human bronchoepithelial (HBE) cells. These results suggested that TDI may not enter HBE cells. In vitro studies, however, showed that TDI avidly forms bis adducts with glutathione (GSH) and that these adducts transfer monoisocyanato-monoglutathionyl-TDI to a sulfhydryl-containing peptide. This study sought to elucidate intracellular reactions of TDI. Using an electron paramagnetic resonance spectrometric (EPR) method, we established that the level of thiol-dependent quenching of phenoxyl radicals of etoposide was decreased >40% in pulmonary tissue of mice that received TDI intrabronchially. Similarly, HBE cells exposed to 100 ppb TDI vapor experienced a >30% reduction in thiol levels as determined with a thiol-specific fluorescent probe (ThioGlo 1). HPLC/UV analysis of lysates from HBE cells exposed to 200 and 500 ppb TDI vapor suggested a dose-related formation of S-glutathionyl adducts. Data from the 500 ppb TDI-treated HBE cells verified the identity of the 2-monoglutathionyl-4-monoisocyanato adduct. The results provide firm evidence that TDI enters pulmonary cells and reacts with GSH. This rapid reaction leading to formation of S-glutathionyl adducts of TDI suggests the importance of cellular thiols in TDI-induced pulmonary disease.     

A robust structure-activity relationship (SAR) model for esters that cause skin irritation in humans.

A structure-activity relationship (SAR) model has been developed to discriminate skin irritant from nonirritant esters. The model is based on the physicochemical properties of 42 esters that were tested in humans for skin irritation. Nineteen physicochemical parameters that represent transport, electronic, and steric properties were calculated for each chemical. Best subsets regression analysis indicated candidate models for further analysis. Regression analyses identified significant models (p < 0.05) that had variables that were also significant (p < 0.05). These candidate models were evaluated using linear discriminant analysis to determine if the irritant esters could be discriminated from nonirritant esters. The stability of the model was evident from the consistency of parameters among ten submodels generated using multiple random sampling of the database. The sensitivity of the ten models, evaluated by "leave-one-out" cross-validation, ranged from 0. 846 to 0.923, with a mean of 0.885 +/- 0.025 (95% CI). The specificity ranged from 0.615 to 0.923, with a mean of 0.738 +/- 0.06 (CI). Compared with nonirritant esters, irritant esters had lower density, lower water solubility, lower sum of partial positive charges, higher Hansen hydrogen bonding parameter, and higher Hansen dispersion parameter. The results indicate that physicochemical features of esters contribute to their ability to cause skin irritation in humans, and that chemical partitioning into the epidermis and intermolecular reactions are likely important components of the response. This model is applicable for prediction of human irritation of esters yet untested.     

Influence of cardiac output on dexmedetomidine pharmacokinetics

Dexmedetomidine, a highly selective alpha(2)-adrenoceptor agonist, reduces the requirements for anesthetic, analgesic, sedative, and hypnotic drugs. Dexmedetomidine pharmacokinetics were characterized in healthy subjects after intravenous administration by means of a computer-controlled infusion pump. A series of seven stepwise increasing pseudo-steady-state plasma concentrations were targeted. The influence of cardiac output on the pharmacokinetics was investigated by use of a compartmental modeling approach in which the elimination clearance was characterized as being either cardiac output independent or dependent. At dexmedetomidine concentrations of 0, 0.6, and 1.2 ng/mL, mean (SD) estimated cardiac outputs were 5. 6 (0.85), 5.1 (0.67), and 4.5 (0.83) L/min, and mean (SD) clearances were 40 (10), 38 (9.0), and 35 (8.5) L/h, respectively. Dexmedetomidine V(SS) and elimination half-life were 72 (19) L and 1. 9 (0.62) h, respectively. The approximately 3 to 19% decrease in cardiac output observed within the anticipated therapeutic range of 0.3 to 1.2 ng/mL was similar to that observed for clonidine. The decrease in cardiac output with increasing plasma concentrations of dexmedetomidine resulted in a corresponding decrease in drug elimination clearance of < or =12% within the therapeutic range; however, this decrease in dexmedetomidine clearance is likely not clinically relevant.     

Robot-assisted laparoscopic prostatectomy in a 68-year-old patient with previous heart transplantation and pelvic irradiation

We report the case of a 68-year-old man who had previously undergone heart transplantation and pelvic irradiation for Hodgkin’s lymphoma and who was under active surveillance for prostate cancer. In response to his increased prostate-specific antigen levels and elevated Gleason score, he was offered robot-assisted laparoscopic prostatectomy.