Analysis of cellular response to isocyanate using N‐succinimidyl N‐methylcarbamate exposure in cultured mammalian cells

Isocyanates (R? N?C?O), one of the highly reactive industrial intermediates, possess the capability to modulate the bio‐molecules by forming toxic metabolites and adducts which may cause adverse health effects. Some of their toxic degradations have previously been unknown and overlooked; of which, molecular repercussions underlying their genetic hazards upon occupational/accidental exposures still remain as an intricate issue and are hitherto unknown. To assess the genotoxic potential of methyl isocyanate in cultured mammalian cells after in vitro exposure, we performed a study in three different normal cell lines MM55.K (mouse kidney epithelial), B/CMBA.Ov (mouse ovarian epithelial), and NIH/3T3 (primary mouse embryonic fibroblast). Cellular DNA damage response was studied for qualitative phosphorylation states of ATM, γH2AX proteins and quantitative state of p53 phosphorylation; DNA cell cycle analysis and measure of cellular apoptotic index before and after treatment were also investigated. Our results demonstrate that methyl isocyanate by negatively regulating the DNA damage response pathway, might promote cell cycle arrest, and apoptosis in cultured mammalian cells suggestive of causing genetic alterations. We anticipate that these data along with other studies reported in the literature would help to design better approaches in risk assessment of occupational and accidental exposure to isocyanates. We also predict that increasing knowledge on DNA damage‐triggered signaling leading to cell death could provide new strategies for investigating the effects of DNA repair disorders and decreased repair capacity on the toxicity and carcinogenic properties of environmental toxins. Environ. Mol. Mutagen., 2009. © 2009 Wiley‐Liss, Inc.     

Combination therapy of dexamethasone with epigallocatechin enhances tibiotarsal bone articulation and modulates oxidative status correlates with cartilage cytokines expression in the early phase of experimental arthritis

The inclusion of antioxidant for the treatment of arthritis, especially under the therapy with immunosuppressant, is motivated because antioxidant plays an essential role in disease progression and moreover, immunosuppressive treatment suffers redox homeostasis balance of the organism. The aim of the present study was to evaluate the enhancement of anti-arthritic effect of dexamethasone in combination with epigallocatechin on the progression of adjuvant-induced arthritis in rats. Adjuvant arthritic rats were treated with dexamethasone (0.2 mg/kg), epigallocatechin (100 mg/kg) and combination of dexamethasone (0.1 mg/kg) with epigallocatechin (100 mg/kg) daily for a period of 28 days. Paw swelling changes, estimation of serum albumin level, alteration of bone mineral density, histopathological, and radiographical analysis were assessed to evaluate the anti-arthritic effect. Lipid peroxidation and antioxidant enzyme activities in joint tissue homogenate were performed along with the expression of different pro-inflammatory cartilage cytokines like TNF-α and IL-6. Dexamethasone and epigallocatechin combination potentiated both the antiarthritic (decrease of hind paw volume) and the antioxidant effect (lipid peroxidation, superoxide dismutase, glutathione reductase and catalase). In combination with dexamethasone, epigallocatechin markedly potentiated the beneficial effect of dexamethasone which resulted in more significant increment of serum albumin and bone mineral density. Improvement of anti-arthritic effect of combination therapy was supported by histopathological, radiographical alterations, and attenuation of over-expression of cartilage cytokines. Epigallocatechin act as potent antioxidant and combined administration of dexamethasone with epigallocatechin increased the anti-arthritic efficacy of basal dexamethasone therapy and suppressed the development phase of arthritic progression in rats.     

Current concepts in the pharmacotherapy of benign prostatic hyperplasia

Benign prostatic hyperplasia is a major men's health issue, with approximately 80% of all men developing this condition within their lifetime. A variety of oral treatments is available, including alpha-adrenoceptor antagonists (alpha-blockers), 5alpha reductase inhibitors, aromatase inhibitors and phytotherapy. A large number of alpha-blockers can be administered, but no single agent has demonstrated a clear superiority over the other drugs. 5alpha Reductase inhibitors have demonstrated similar efficacy in larger volume prostates but most evidence suggests that there is no benefit in combining them with alpha-blockers. The use of phytotherapy is not entirely novel but requires further long-term evaluation before it can be endorsed for clinical use in benign prostatic hyperplasia.     

A retrospective review of pharyngeal pouch surgery in 56 patients

We retrospectively reviewed 56 consecutive patients treated surgically for a pharyngeal pouch at our institution between 1989-1999 (10 years). Various surgical procedures were performed including endoscopic stapling (20), external excision (23), Dohlman's procedure (9), pouch inversion (3), cricopharyngeal myotomy only (3), and pouch suspension (1). There were 12 patients (18%) with complications and one mortality (2%). Four patients (7%) had a recurrence with 2 requiring further surgery. Over the latter 3 years, endoscopic stapling has emerged as the primary procedure for pharyngeal pouch surgery in our unit; with the advantages of an earlier commencement of diet and earlier hospital discharge. However, results were not as good as for external excisions. Furthermore, there were difficulties with 3 cases that commenced as endoscopic stapling procedures but had to he converted to external excisions due to inaccessibility in one case and iatrogenic perforations in two cases. As with any new technique, problems may occur and a learning curve has been appreciated in our unit. Surgeons must he prepared, with informed consent, to convert to an external approach should difficulties arise during endoscopic stapling. Elderly and frail patients who are at risk from a general anaesthetic may benefit from endoscopic stapling. External excision of pharyngeal pouches may be more appropriate in the young, the medically fit, and when malignancy is a concern.     

Measurement of brain tissue oxygenation performed using positron emission tomography scanning to validate a novel monitoring method

OBJECT: The benefits of measuring cerebral oxygenation in patients with brain injury are well accepted; however, jugular bulb oximetry, which is currently the most popular monitoring technique used has several shortcomings. The goal of this study was to validate the use of a new multiparameter sensor that measures brain tissue oxygenation and metabolism (Neurotrend) by comparing it with positron emission tomography (PET) scanning. METHODS: A Neurotrend sensor was inserted into the frontal region of the brain in 19 patients admitted to the neurointensive care unit. After a period of stabilization, the patients were transferred to the PET scanner suite where C15O, 15O2, and H2(15)O PET scans were obtained to facilitate calculation of regional cerebral blood volume, O2 metabolism, blood flow, and O2 extraction fraction (OEF). Patients were given hyperventilation therapy to decrease arterial CO2 by approximately 1 kPa (7.5 mm Hg) and the same sequence of PET scans was repeated. For each scanning sequence, end-capillary O2 tension (PvO2) was calculated from the OEF and compared with the reading of brain tissue O2 pressure (PbO2) provided by the sensor. In three patients the sensor was inserted into areas of contusion and these patients were eliminated from the analysis. In the subset of 16 patients in whom the sensor was placed in healthy brain, no correlation was found between the absolute values of PbO2 and PvO2 (r = 0.2, p = 0.29); however a significant correlation was obtained between the change in PbO2 (deltaPbO2) and the change in PvO2 (deltaPvO2) produced by hyperventilation in a 20-mm region of interest around the sensor (p = 0.78, p = 0.0035). CONCLUSIONS: The lack of correlation between the absolute values of PbO2 and PvO2 indicates that PbO2 cannot be used as a substitute for PvO2. Nevertheless, the positive correlation between deltaPbO2 and deltaPvO2 when the sensor had been inserted into healthy brain suggests that tissue PO2 monitoring may provide a useful tool to assess the effect of therapeutic interventions in brain injury.     

Effect of paternal administration of an antiestrogen, tamoxifen on embryo development in rats

We have earlier reported that oral administration of tamoxifen causes a dose-dependent reduction in the fertility of adult male rats. The decrease in fertility was mainly due to an increase in pre-implantation loss without an effect on fertilizing ability. During the study, an increased incidence of post-implantation loss of conceptuses sired by tamoxifen-treated male rats was observed. A detailed study was undertaken to investigate dose-related changes in pre- and post-implantation loss and the stage(s) of development at which these losses occurred. The present study demonstrates that tamoxifen treatment produced few normal litters as well as significantly increased pre-implantation loss without affecting the rate of fertilization. Also a significant increase in the number of degenerating embryos at the 2–4-cell stage (days 1–2 of gestation), retrieved from the oviduct/uterus of females mated with tamoxifen-treated males was observed. Histology of the resorbed fetuses, in both control and treated groups, showed presence of trophoblast outgrowth indicative of early placenta formation, which normally occurs on days 8–9 of gestation. The present results suggest that pre-implantation loss occurred at the 2–4-cell stage and the post-implantation loss occurred around days 8–9 of gestation, i.e. around midgestation. The possible effects of paternal tamoxifen treatment on embryogenesis may be due to the reduction of androgens or by the blockage of the estrogen receptor by tamoxifen, thereby affecting germ cell maturation during spermatogenesis.     

In vivo monastral blue-induced lamellar-bodies in lysosomes of pulmonary intravascular macrophages (PIMs) of bovine lung: Implications of the surface coat

We previously reported that the pulmonary intravascular macrophages (PIMs) of sheep, goat, and calf lung contained a heparin and a lipolytic lipase sensitive surface coat by using tannic acid as a component of paraformaldehyde-glutaraldehyde-based fixative. The implication of this sensitivity was that the surface coat was predominantly comprised of lipoprotein-like substance. In this study we report that monastral blue (MB) used as a vascular tracer interacted with the coat globules and lost its original particulate appearance. Its precise localization in the PIMs was in combination with altered macromolecules of the surface coat in the form of lipid droplets, which conformed to the conventional view of neutral lipids. In contrast, pigment particles examined in their native state resembled metalic particles as electron-dense eliptical rods. The lipid droplets were subsequently internalized through endocytic route and found their access into the lysosomal compartments of PIMs at the electron microscopic level. Lamellar bodies (LLBs) arose from the lysosomal matrix after the entry of lipid droplets in the secondary lysosomes. Acid phosphatase activity was located in secondary lysosomes as well as in endosomes. These observations suggest that coat granules of the PIMs acted as a carrier of exogenous MB particles to deliver the complex to the lysosomal compartment where partial digestion lead to the formation of lamellar bodies. The implications of MB (cationic dye) as a vascular tracer for studying phagocytic index of PIMs in the light of their coat and the rapid development of LLBs are discussed. It is proposed that MB by initially combining with the surface coat provokes mobilization of intracellular lipid pools. In this way metabolism of vasoactive lipid in the PIMs is stimulated to influence the dynamics of pulmonary circulation in the calves.© Willey-Liss, Inc.