The increased incidence of fungal infections in the recent past has been attributed to the increase in the number of human immunodeficiency virus-positive and AIDS patients. Early diagnosis of mycoses in patients is crucial for prompt antifungal therapy. Immunological methods of diagnosis have not been found to be satisfactory, and recent research has been diverted to the use of PCR for the sensitive and early diagnosis at the molecular level. In the present study we targeted different regions of the rRNA gene to diagnose cases of mycotic keratitis and identify the causal agents. Six fungus-specific primers (primers ITS1, ITS2, ITS3, ITS4, invSR1R, and LR12R) were used, and the amplified products were analyzed by single-stranded conformation polymorphism (SSCP) analysis. Dendrograms of these SSCP patterns, prepared on the basis of Jaccard's coefficient, indicated that the PCR products obtained with primer pair ITS1 and ITS2 were the best for the identification of fungi. The results were confirmed by sequencing of the PCR products, and the approach was successfully tested experimentally for the detection of mycotic keratitis caused by Aspergillus fumigatus and was used for the diagnosis of fungal corneal ulcers in patients.Mycotic keratitis or fungal corneal infections have a worldwide distribution, and the incidence is higher in tropical and subtropical countries (8). More than 105 species of fungi belonging to 56 genera have been reported to cause oculomycosis. However, species of Fusarium, Aspergillus, Candida, and other hyaline and dematiaceous hyphomycetes are the usual isolates from patients with mycotic keratitis (20). The management of keratomycosis depends on rapid identification of the causal agent. The diagnosis is often delayed because of the poor availability of infected material from the cornea and the slow growth of a large number of fungi in routinely used culture media, and therefore, early intervention is not always possible and the patient's vision is often lost. In general, the diagnosis of fungal corneal ulcer is dependent on Gram and Giemsa staining, which have low sensitivities of about 50 to 80% (4). Recent advances in molecular biology techniques have opened the door for culture-independent diagnostic methods. Immunological detection (13) and identification by use of distinctive metabolites (2) and nucleic acid probes (7,25) are the tools most often used for diagnosis. One such technique is PCR, which has been shown to be useful for the culture-independent diagnosis of various microbial infections, including mycoses (10,11,22). To date, a few cases of mycotic keratitis have successfully been diagnosed by PCR (5, 6).Ribosomal DNA is the most conserved region in the genome, with capabilities of phylogenetic divergence (14). The whole rRNA gene contains a small subunit (SSU) 18S rRNA, 5.8S rRNA, and a large subunit (LSU) 28S rRNA. Internal transcribed spacer (ITS) region I (ITSI) and ITSII are more variable than the rest of the ribosomal gene subunits and are found between SSU rRNA and 5.8S ...

The increased incidence of fungal infections in the recent past has been attributed to the increase in the number of human immunodeficiency virus-positive and AIDS patients. Early diagnosis of mycoses in patients is crucial for prompt antifungal therapy. The yield of clinical examination in the diagnosis of keratomycosis is 63-83% and KOH mount is 91%. This still highlights the limitation of routine clinical examination and smear examination, which is not performing 100% efficiently. It is for these 37%, 17% and 9% of cases, every day advanced technologies are called for. Those who deal with patient care are aware of certainties and uncertainties of results of clinical examination. The best reported figures at specialized centres might not translate into clinical practice. Another factor to be kept in mind is that many patients who come after secondary and tertiary referrals are already treated with antibiotics, antivirals, steroids and sometimes even antifungals that distort the clinical picture completely. Further, one has to consider as well the cases caused by yeast-like fungi, which resemble bacterial keratitis. Confirmation of diagnosis, not only in case of mycotic keratitis but also for other diseases, to initiate prompt and accurate therapy would avoid unnecessary and indiscriminate use of steroids/antibacterials/antivirals and antifungals.

The first detailed experimental study of the deactivation of cationic gold was conducted, and the influence of each component in the reaction system (substrate, counterion, solvent) on the decay process was examined. It was found that a substrate (alkyne/allene/alkene)-induced disproportionation of gold(I) may play a key role in the decay process. Our mechanism is supported by kinetic, XPS, voltammetry studies, and high-resolution ESI-MS data.

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Additives that are good hydrogen-bond acceptors increase the efficiency of gold-catalyzed reactions in those instances where protodeauration is the rate-determining step. The efficiency of additives capable of hydrogen-bonding-assisted protodeauration correlated with their standing in a scale of hydrogen bonding basicity (measured by pKBHX). All additives used in the study are commercially available.

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A systematic study on the effects of Lewis or Brønsted acid co-catalysts in gold-catalyzed reactions was undertaken using representative reactions (O-, N-, and C-nucleophilic additions to alkynes). Through these reactions, it was demonstrated that an acidic co-catalyst can increase the catalyst turnover significantly, enabling practical reaction rates at competitive catalyst loadings (<1 mol %). Further investigation is currently underway to improve the understanding of the subtle principles underlying these experimental observations.

Some unique features of 1-isothiocyanatosilatrane, 1, include concomitant NMR couplings of quadrupolar 14N(NCS) nucleus with adjacent heteroatoms [J(13C−14N) = 26.17 Hz; J(29Si−14N) = 28.47 Hz] and the crystallographically determined shortest N→Si bond, 2.007(3) Å, as well as a nearly linear structure of the heteroatoms N(1)−Si−N(2)−C(7)−S(1). Contrary to the known reactivity of tetracoordinate isothiocyanatosilanes, 1 invariably shows retention of the Si−N(CS) bond under normal nucleophilic/electrophilic reaction conditions. These novel features also get support from semiemperical MO calculations on the compound.