Fine needle aspiration cytology diagnosis of cutaneous leishmaniasis in a 6-month-old child: a case report.

BACKGROUND: Skin biopsy and scrape smear examination are the two most commonly employed investigatory techniques in the diagnosis of cutaneous leishmaniasis. Although cases Leishmania lymphadenitis are reliably diagnosed with fine needle aspiration (FNA) cytology, it has not attained popularity in the diagnosis of cutaneous leishmaniasis, and only a few reports are available. CASE: A 6-month-old Kuwaiti child presented with a skin lesion on her left forearm of five months' duration. Both scrape smears and FNA were performed from the lesion. FNA cytology smears showed a rich population of inflammatory cells predominating in lymphocytes and histiocytes and epithelioid cell granulomas. The amastigote forms of Leishmania were noted on the smears. The scrape smears were nondiagnostic. CONCLUSION: FNA cytology can be reliably used in the diagnosis of cutaneous leishmaniasis, especially in dry lesions, where scrape smears are likely to be nondiagnostic.     

A hypothesis and theoretical model speculating the possible role of therapy mediated neoplastic cell loss in promoting the process of glioblastoma relapse

Tumor recurrence is considered to be one of the biggest culprits, behind the poor prognosis of glioblastomas. Using published facts on primary glioblastomas, with special reference to cancer stem cells and their recently described heterogeneity, a hypothesis is being proposed that speculates the possible role of therapy mediated neoplastic cell loss in promoting the process of relapse in these tumors. The mechanisms by which such a phenomenon could be functional has been integrated into a double version theoretical model, which envisages glioblastomas as neoplasms comprising of multiple, differentially regulated and dynamically distinct neoplastic compartments (named as active and back-up compartments in this article) supported by their own complement of cancer stem cells, wherein therapy mediated cell loss, which mainly affects the size of the active compartment, results in abrogating the inhibitory effect of the active compartment on the back-up compartment, thereby leading to the activation of the back-up compartment. This activation contributes towards tumor recurrence. The possibility of the existence of such a phenomenon could have strong implications on management and prognosis of these tumors. This article aims to provoke discussion and generate new ideas for further research.     

Matrix metalloproteinase-assisted triggered release of liposomal contents

We offer a novel methodology for formulating liposomes by incorporating sequence-specific collagen-mimetic peptides such that they are specifically "uncorked" by a matrix metalloproteinase, MMP-9. By encapsulating carboxyfluorescein (as a self-quenching fluorescent dye), we demonstrate that the time-dependent release of the dye from liposomes is due to the specific enzymatic cleavage of the surface-exposed collagen-mimetic peptides. The specificity of such cleavage is attested by the fact that the liposomal "uncorking" and their content release occur only by MMP-9 and not by a general proteolytic enzyme, trypsin, despite the fact that the collagen mimetic peptides contain the trypsin cleavage site. The mechanistic details underlying the formulations of liposomes and their enzyme-selective "uncorking" and content release are discussed. Arguments are presented that such liposomes can be fine-tuned to serve as the drug delivery vehicles for the detection and treatment of various human diseases, which occur due to the overexpression of a variety of pathogenic matrix metalloproteinases.     

Roadside revegetation by native plants: I. Roadside microhabitats,floristic zonation and species traits

Recognizing the severity of road effects and need for developing a natural and self-sustained roadside vegetation cover, this study aimed to provide an ecological basis for selecting desirable native plants based on their autecological attributes by floristic analysis of naturally colonized plants in roadside microhabitats. We hypothesized that (i) vegetation zonation along roadsides is a function of the different microtopography and substrate types (microhabitats) created by road construction and (ii) plant colonization in these microhabitats is dependant upon the presence of suitable regeneration traits adapted to the specific microhabitats. We identified four distinct microhabitats namely shoulder, side slope, ditch and back slope from the edge of the road to the edge of the forest. We conducted vegetation and soil analyses in these microhabitats along 34 random transects running perpendicular to the road to the edge of forest in a 14 km section of the Trans Canada Highway (TCH) in Terra Nova National Park (TNNP), Newfoundland, Canada. The multi-response permutation procedure (MRPP) confirmed that the plant communities of the four roadside microhabitats were significantly different from each other. Canonical correspondence analysis (CCA) showed that composition of roadside plant communities was related to gradients of soil moisture content, bulk density, organic matter depth and pH. Several indicator plants, determined by indicator species analysis (ISA), were abundant in their respective microhabitats, indicating their affinity to particular sets of environmental conditions. The root–shoot analysis of selected dominant plants across the roadside habitats revealed that plants of a particular microhabitat had similar above and below ground spread and biomass allocation patterns.We found that floristic zonation along roadsides is a function of roadside microtopography, substrate type and environmental gradients created by the road building process. The similarities in above and below ground spread and biomass allocation patterns of dominant plants of respective microhabitats could be used as a basis of interpreting the role of autecological attributes of the species that enable them to establish in specific microhabitats. Several native plants, such as Empetrum nigrum, Juniperus communis, Vaccinium angustifolium, Trifolium repens, and Anaphalis margaritaceae are naturally abundant in side slopes and possess autecological attributes such as low stature, widespread above- and below-ground parts, and drought tolerance. Presence of these desirable properties and their perennial habit make them excellent candidates for roadside revegetation.     

Synthesis of barbiturate-based methionine aminopeptidase-1 inhibitors

The syntheses of a new class of barbiturate-based inhibitors for human and Escherichia Coli methionine aminopeptidase-1 (MetAP-1) are described. Some of the synthesized inhibitors show selective inhibition of the human enzyme with high potency.     

Recognition of secretory proteins in <Emphasis Type="Italic">Escherichia coli</Emphasis> requires signals in addition to the signal sequence and slow folding

Background  

The Sec-dependent protein export apparatus of Escherichia coli is very efficient at correctly identifying proteins to be exported from the cytoplasm. Even bacterial strains that carry prl mutations, which allow export of signal sequence-defective precursors, accurately differentiate between cytoplasmic and mutant secretory proteins. It was proposed previously that the basis for this precise discrimination is the slow folding rate of secretory proteins, resulting in binding by the secretory chaperone, SecB, and subsequent targeting to translocase. Based on this proposal, we hypothesized that a cytoplasmic protein containing a mutation that slows its rate of folding would be recognized by SecB and therefore targeted to the Sec pathway. In a Prl suppressor strain the mutant protein would be exported to the periplasm due to loss of ability to reject non-secretory proteins from the pathway.     

Mechanism of ubiquitin recognition by the CUE domain of Vps9p

Coupling of ubiquitin conjugation to ER degradation (CUE) domains are approximately 50 amino acid monoubiquitin binding motifs found in proteins of trafficking and ubiquitination pathways. The 2.3 A structure of the Vps9p-CUE domain is a dimeric domain-swapped variant of the ubiquitin binding UBA domain. The 1.7 A structure of the CUE:ubiquitin complex shows that one CUE dimer binds one ubiquitin molecule. The bound CUE dimer is kinked relative to the unbound CUE dimer and wraps around ubiquitin. The CUE monomer contains two ubiquitin binding surfaces on opposite faces of the molecule that cannot bind simultaneously to a single ubiquitin molecule. Dimerization of the CUE domain allows both surfaces to contact a single ubiquitin molecule, providing a mechanism for high-affinity binding to monoubiquitin.     

Conformational interconversion in compstatin probed with molecular dynamics simulations

Compstatin is a 13-residue cyclic peptide that has the potential to become a therapeutic agent against unregulated complement activation. In our effort to understand the structural and dynamic characteristics of compstatin that form the basis for rational and combinatorial optimization of structure and activity, we performed 1-ns molecular dynamics (MD) simulations. We used as input in the MD simulations the ensemble of 21 lowest energy NMR structures, the average minimized structure, and a global optimization structure. At the end of the MD simulations we identified five conformations, with populations ranging between 9% and 44%. These conformations are as follows: 1) coil with alphaR-alphaR beta-turn, as was the conformation of the initial ensemble of NMR structures; 2) beta-hairpin with epsilon-alphaR beta-turn; 3) beta-hairpin with alphaR-alphaR beta-turn; 4) beta-hairpin with alphaR-beta beta-turn; and 5) alpha-helical. Conformational switch was possible with small amplitude backbone motions of the order of 0.1-0.4 A and free energy barrier crossing of 2-11 kcal/mol. All of the 21 MD structures corresponding to the NMR ensemble possessed a beta-turn, with 14 structures retaining the alphaR-alphaR beta-turn type, but the average minimized structure and the global optimization structures were converted to alpha-helical conformations. Overall, the MD simulations have aided to gain insight into the conformational space sampled by compstatin and have provided a measure of conformational interconversion. The calculated conformers will be useful as structural and possibly dynamic templates for optimization in the design of compstatin using structure-activity relations (SAR) or dynamics-activity relations (DAR).     

Spacer-based selectivity in the binding of "two-prong" ligands to recombinant human carbonic anhydrase I

Benzenesulfonamide and iminodiacetate (IDA)-conjugated Cu(2+) independently interact at the active site and a peripheral site of carbonic anhydrases, respectively [Banerjee, A. L., Swanson, M., Roy, B. C., Jia, X., Haldar, M. K., Mallik, S., and Srivastava, D. K. (2004) J. Am. Chem. Soc. 126, 10875-10883]. By attaching IDA-bound Cu(2+) to benzenesulfonamide via different chain length spacers, we synthesized two "two-prong" ligands, L1 and L2, in which the distances between Cu(2+) and NH(2) group of sulfonamide were 29 and 22 A, respectively. We compared the binding affinities of L1 and L2, vis-a-vis their parent compound, benzenesulfonamide, for recombinant human carbonic anhydrase I (hCA-I) by performing the fluorescence titration and steady-state kinetic experiments. The experimental data revealed that whereas the binding affinity of L1 for hCA-I was similar to that of benzenesulfonamide, the binding affinity of L2 was approximately 2 orders of magnitude higher, making L2 one of the most potent ligands or inhibitors of hCA-I. Since the enhanced binding or inhibitory potency of L2 is diminished (to the level of benzenesulfonamide) either in the presence of EDTA or upon treatment of the enzyme with diethyl pyrocarbonate, it is proposed that Cu(2+) of L2 interacts with one of the surface-exposed histidine residues of the enzyme. A cumulative account of the experimental data leads to the suggestion that the differential binding of L1 versus L2 to hCA-I is encoded in the chain length of the spacer moiety.     

Indirect effects of black spruce (Picea mariana) cover on community structure and function in sheep laurel (Kalmia angustifolia) dominated heath of eastern Canada

Recent studies on phenotypic plasticity of plant traits indicate that within-species variation in litter quality may be a significant factor that feeds back on litter decomposition and nutrient cycling rates at the stand level. These findings may be especially significant for understanding biodiversity-stability relationships in species-poor ecosystems that have little functional redundancy among primary producers. We tested the null hypothesis that black spruce and Kalmia were functional equivalents with respect to their structuring roles of subordinate vegetation and their influence on site biogeochemistry. The purpose of the study was to determine the degree to which forest cover exerts top-down control on community structure and function of Kalmia-black spruce communities. This community type dominates much of the forest understory and unforested heathlands in Atlantic Canada. We intensively studied a representative stand of Kalmia heath in Terra Nova National Park in eastern Newfoundland. Thirty-two 0.5 m × 0.5 m sample plots were randomly distributed among five transects bisecting gradients in dominance of black spruce and Kalmia. Light levels, species composition, vascular plant cover and soil respiration rate were determined for each plot. Tissue samples of litter, mature and current year leaves of Kalmia were collected and analyzed for nutrient status. Herbaceous species richness and cover peaked at intermediate light levels. Kalmia foliar N concentration and above-ground biomass increased with increasing shade. Soil respiration rates were strongly related to the light gradient and increased with increasing quality of Kalmia litter inputs. Our data indicate that Kalmias vigour and foliar nitrogen concentrations are greater under black spruce canopy as opposed to heath condition and that the shaded phenotype has relatively benign feedbacks on soil productivity compared to the open-habitat phenotype. In the absence of functional diversity at the species level in these species-poor habitats, phenotypic plasticity in Kalmia appears to be an important dimension of the biodiversity-stability relationship in these communities since our data suggest that this species has the potential either to inhibit or facilitate carbon cycling and the pathway is strongly linked to the presence or absence of overstory cover. The role of forest regeneration as an indirect control of forest soil processes such as carbon and nitrogen cycling in this ecosystem is discussed.