Molecular diagnosis of antimicrobial resistance

Advances in molecular technology have helped in better understanding of mechanisms and diagnosis of diseases in many medical fields. Several molecular techniques are available for determining the genotypic drug-resistance and monitoring epidemic spread of a particular antimicrobial resistance gene in a hospital or patient population. The molecular (genotypic) testing has several advantages over conventional (phenotypic) testing in being faster and unambiguous, more accurate, able to detect masked resistance and can serve as a "gold" or "reference" test for detecting antibiotic resistance genes. This article addresses these molecular tests with their application and limitations and provide examples of their use especially in Mycobacterium tuberculosis and methicillin resistant Staphylococcus aureus.     

Prognostic significance of metastasis-associated protein S100A4 (Mts1) in prostate cancer progression and chemoprevention regimens in an autochthonous mouse model.

PURPOSE: We recently showed that metastasis-promoting Mts1 gene (S100A4) and protein is overexpressed during progression of prostate cancer in humans. The purpose of this study was to assess the expression of S100A4 during autochthonous prostate cancer progression in transgenic adenocarcinoma of the mouse prostate (TRAMP) model. Because oral consumption of green tea polyphenols (GTP) has been shown to inhibit metastasis and prostate cancer in TRAMP, we further assessed the significance of S100A4 during chemoprevention regimen. EXPERIMENTAL DESIGN: Male TRAMP mice 8 weeks of age were equally divided into two groups. A freshly prepared 0.1% GTP solution in tap water was supplied thrice a week to experimental animals as the sole source of drinking fluid for 24 weeks, whereas the control group of animals received the same tap water throughout the experiment. The animals were sacrificed at 0, 8, 16, and 24 weeks of GTP feeding and were analyzed for S100A4 and E-cadherin. Additional untreated and treated nontransgenic controls were also included in the study. RESULTS: With the progression of age and prostate cancer growth in TRAMP mice, an increase in the expression of S100A4 at mRNA and protein level in dorsolateral prostate, but not in nontransgenic mice, occurred. GTP feeding to TRAMP mice resulted in marked inhibition of prostate cancer progression, which was associated with reduction of S100A4 and restoration of E-cadherin. CONCLUSIONS: S100A4 represents a promising marker for prostate cancer progression and could be employed as a biomarker in chemoprevention regimens.     

Evaluation of cytotoxic, oxidative stress, proinflammatory and genotoxic responses of micro- and nano-particles of dolomite on human lung epithelial cells A(549)

Dolomite is a natural mineral of great industrial importance and used worldwide, thus millions of workers are at risk of occupational exposure. Its toxicity is however, meagerly documented. In the present investigation, a dolomite powder obtained from its milling unit was analyzed by some standard methods namely, optical microscopy, transmission electron microscopy and dynamic light scattering. Results showed that dolomite powder contained particles of different shapes and size both microparticles (MPs) and nanoparticles (NPs), suggesting potential occupational exposure of these particles. An attempt was therefore, made to investigate dolomite toxicity in a particle size-dependent manner in human lung epithelial cells A(549). The comparative toxicity evaluation of MPs and NPs was carried out by assessing their effects on cell viability, membrane damage, glutathione, reactive oxygen species (ROS), lipid peroxidation (LPO), micronucleus (MN) and proinflammatory cytokines, namely tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6). These markers of cytotoxicity, genotoxicity and inflammation were assayed in cells exposed to MPs and NPs in a dose-and time-dependent manner. Invariably, their toxic effects were dose-and time-dependent while NPs in general were significantly more toxic. Notably, NPs caused oxidative stress, genotoxicity and inflammatory responses, as seen by significant induction of ROS, LPO, MN, TNF-α, IL-1β and IL-6. Thus, the study tends to suggest that separate health safety standards would be required for micrometer and nanometer scale particles of dolomite.     

Clinicopathological findings of a natural outbreak of Theileria annulata in cattle: an emerging disease in southern Iran

Theileriosis is an economically important hemoprotozoal disease with high morbidity and mortality in cattle. The present study reported the pathological features of a natural outbreak of tropical bovine theileriosis due to Theileria annulata in Fars Province, southern Iran. T. annulata was confirmed by the presence of T. annulata piroplasms in the blood smears and also by polymerase chain reaction test. On necropsy, pale mucous membranes and petechial and ecchymotic hemorrhages in the mucosal and serosal surfaces together with lymphadenopathy were observed. The liver was friable, yellowish, and larger than normal. Hemorrhages and punched-out ulcers were observed in the abomasal mucous membrane. Severe petechial hemorrhages were seen in the skin particularly in the hairless areas. Pulmonary edema and emphysema with petechial and ecchymotic hemorrhagic foci in the lungs were evident. The main histological changes were proliferation of lymphocytes in the lymph nodes and proliferation of macrophages, lymphocytes, and plasma cells in the spleen, Peyer's patches, portal tracts of the liver, and interstitial tissue of the kidneys. The mucous membrane of the abomasum showed numerous multifocal areas of necrosis and ulceration, and the submucosal area and lamina propria adjacent to these lesions showed hyperemia and hemorrhages, with mononuclear cell infiltration. The skin showed multifocal necrotic changes, petechial and ecchymotic hemorrhages, and chronic dermatitis. The schizonts of Theileria were evident in the cytoplasm of the lymphocytes and macrophages of the lymph nodes, spleen, and skin. Molecular examination revealed that these animals were infected with T. annulata. The present study describes the clinicopathological findings of bovine tropical theileriosis in an unpredictable weather condition.     

Blood-Brain Barrier Permeability of Asiaticoside,Madecassoside and Asiatic Acid in Porcine Brain Endothelial Cell Model

Neurotherapeutic potentials of Centella asiatica and its reputation to boost memory, prevent cognitive deficits and improve brain functions are widely acknowledged. The plant's bioactive compounds, i.e. asiaticoside, madecassoside and asiatic acid were reported to have central nervous system (CNS) actions, particularly in protecting the brain against neurodegenerative disorders. Hence, it is important for these compounds to cross the blood-brain barrier (BBB) to be clinically effective therapeutics. This study aimed to explore the capability of asiaticoside, madecassoside and asiatic acid to cross the BBB using in vitro BBB model from primary porcine brain endothelial cells (PBECs). Our findings showed that asiaticoside, madecassoside and asiatic acid are highly BBB permeable with apparent permeability (P_app) of 70.61 ± 6.60, 53.31 ± 12.55 and 50.94 ± 10.91 × 10^?6 cm/s respectively. No evidence of cytotoxicity and tight junction disruption of the PBECs were observed in the presence of these compounds. Asiatic acid showed cytoprotective effect towards the PBECs against oxidative stress. This study reported for the first time that Centella asiatica compounds demonstrated high capability to cross the BBB, comparable to central nervous system drugs, and therefore warrant further development as therapeutics for the treatment of neurodegenerative diseases.