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The conformational equilibrium of methyl 4-nitrophenyl sulfoxide (MNPSO) was experimentally investigated in the gas phase by using microwave spectroscopy and in isotropic and nematic liquid-crystal solutions, in which the solvents are nonaqueous and aprotic, by using NMR spectroscopy; moreover, it was theoretically studied in vacuo and in solution at different levels of theory. The overall set of results indicates a significant dependence of the solute conformational distribution on the solvent dielectric permittivity constant: when dissolved in low-polarity media, the most stable conformation of MNPSO proved to be strongly twisted with respect to that in more polar solvents, in which the conformational distribution maximum essentially coincides with that obtained in the gas phase. We discuss a possible explanation of this behavior, which rests on electrostatic solute-solvent interactions and is supported by calculations of the solute electric dipole moment as a function of the torsional angle. This function shows that the least polar conformation of MNPSO is located at a twist angle close to that of the conformational distribution maximum found in less-polar solvents. This fact, associated with a relatively flat torsional potential, can justify the stabilization of the twisted conformation by the less-polar solvents.

We report the Fourier transform microwave spectra of four isotopologues of the hetero trimer pyridine-ArNe, formed by the combination of two isotopes of the nitrogen atom (14N and 15N) in pyridine with two isotopes of the rare gas (RG) atoms (20Ne and 22Ne), by using pulsed jet spectroscopy. We detected the conformer denoted [1,1], with the Ne and Ar atoms located one on each side of the ring plane. The [2,0] species, with the two rare gas atoms on the same side of the ring, was not observed. MP2/6-311++G** ab initio calculations suggest the rotational spectrum of this species to be complicated by the presence of several almost equivalent minima, separated by very low barriers. Four structural van der Waals parameters, RAr, RNe, θAr and θNe, which localize the RG atoms with respect to pyridine, have been determined. The 14N nuclear quadrupole coupling constants have been obtained for the isotopologues containing this nucleus.

Changes to fire regimes have resulted in excessive shrub growth and declines in the species rich herbaceous ground layer of pyric savanna and grassland systems worldwide, including the pine flatwoods of the Southern Coastal Plain of the United States. Prescribed burning and roller chopping during growing (April–October) and dormant (November–March) seasons are management practices promoted to reduce shrub invasion and increase herbaceous plant growth in flatwoods. However, relatively little is known about the seasonal effects these activities have on shrubs and herbaceous vegetation. We assessed the effects of prescribed burning and roller chopping on herbaceous and shrub characteristics in pine flatwoods and explored how grazing may mediate these treatments. We used a paired design, with comparison made between sampling locations randomly located within treated (e.g. burned) and adjacent untreated areas. Growing season burning was more effective at reducing shrub cover and height than dormant season burning. However, shrub re-growth occurred the second year post-burn. Roller chopping and roller chopping/burning combinations led to decreases in shrub cover and height for 2 years post-treatment. Decreases in shrub density were seen on sites subject to growing season roller chopping and grazing. Decreases in herbaceous vegetation were observed following all treatments, possibly the result of grazing. If reductions in shrub density are required, growing season roller chopping in combination with grazing may be the only effective treatment. However, initial deferment from grazing following burning and roller chopping treatments may be necessary to permit re-establishment and growth of forbs and graminoids.

Two different complexes of ammonia with two different conformers of glycidol have been characterized by Fourier transform microwave spectroscopy. In both complexes NH3 is linked to the alcohol molecule through an O-H•••N (stronger) and an N-H•••O (weaker) hydrogen bond. The determined V3 barriers to internal rotation of the ammonia moiety, 3.522(2) and 2.270(1) kJ/mol for the G1-NH3, and G2-NH3, respectively, correspond to the energy of the N-H•••O interaction. Structural and energetic features of the hydrogen bonds are given.

The Cockscomb Basin Wildlife Sanctuary, Belize was established in 1986 following Rabinowitz and Nottingham's 1986 study on jaguar diet and distribution. In 2002, we reexamined jaguar diet following two decades of mitigated human hunting of jaguar prey. We observed high overlap between historical and current jaguar diet constructs. Nine-banded armadillo remained the most frequently consumed prey item. However, collared peccary consumption increased by nearly 20 percent while dietary breadth decreased by 60 percent presumably reflecting increased prey availability following reduced human hunting pressure.

Jaguars Panthera onca inhabiting tropical or subtropical evergreen moist forest have often been classified as opportunistic predators because they consume prey relative to its availability. However, these studies failed to address simultaneously the distribution of predator and prey through time and space, which may lead to an incomplete or erroneous understanding of jaguar foraging strategies. In this study, we reconstructed jaguar diet from scat, and used camera traps to investigate jaguar prey availability and the distribution of jaguar and its prey through space and time. We focused our examination of predator–prey temporal and spatial relations on forest infrastructure comprising man-made paths, small mammal trails, tapir Tapirus bairdi trail and trail-less, forested areas as they represent distinct habitats for prey selection. Overall, we observed high overlap between the prey used and available, suggestive of opportunistic foraging. However, jaguars exhibited selective tendencies in discriminating between larger prey. Jaguars used collared peccary Tayassu tajacu greater than its availability, while preying upon the equally abundant and similarly distributed white-lipped peccary Tayassu pecari and tapir less than predicted based upon availability. Armadillo Dasypus novemcinctus and paca Agouti paca, 56.6% of total consumption, were consumed relative to availability but exhibited low spatial overlap with jaguar. Armadillo and paca used trail-less, forested areas and small mammal trails not used by jaguar and were photographed more frequently at greater distances from man-made paths, major thoroughfares for jaguars. This study suggests that although forest jaguars use prey relative to its abundance, jaguars may rely on foraging strategies other than chance encounters for exploiting prey.

A goal of many resource selection studies is to identify those habitats selected by a species. However, favorability of a particular habitat feature is likely contingent on such factors as landscape composition, predation risk, and an individual's resource needs. Thus, habitat selection may vary depending on context, and identifying causes of variability in habitat use could increase our understanding of functional aspects of a species' habitat ecology. Clear-cuts afford ruffed grouse (Bonasa umbellus) important escape cover, whereas access routes (roads and trails) and mesic bottomlands are viewed as important foraging areas for this species. We present a study of factors influencing strength of selection (i.e., use-availability) for these 3 habitat features by individual ruffed grouse. We analyzed radiotelemetry data from >1,000 ruffed grouse monitored on 10 study sites in the central and southern Appalachians. Five sites were typified by mixed-mesophytic forests, and 5 were predominantly oak-hickory forests. Selection for clear-cuts was positively related to selection for access routes, but it was inversely related to selection for mesic bottomlands. Selection for mesic bottomlands and selection for access routes were positively related in oak-hickory forests, but they were unrelated in mixed-mesophytic forests. Clear-cuts were more strongly selected in mixed-mesophytic forests, and within each forest type, use of clear-cuts was strongest by adult males. Mesic bottomlands were only selected in oak-hickory forests, and within these forests they were most strongly selected by adult females. Following poor, hard-mast crops, use of access routes by female grouse increased. Use of clear-cuts and bottomlands increased for some or all sex and age classes of grouse following closure of hunting, suggesting that hunting discouraged use of these covers. Animals typically face a trade-off between survival and condition to maximize fitness, and our observations suggest that (relative to one another) male grouse favor refuging habitats whereas females favor foraging areas. At a landscape scale, grouse in areas having oak-hickory forests selected foraging habitats more strongly, whereas those inhabiting mixed-mesophytic forests made greater use of escape cover. Our findings indicate that habitat management prescriptions for Appalachian grouse can be tailored by forest type.

Ruffed grouse (Bonasa umbellus; hereafter, grouse) populations in the central and southern Appalachians are experiencing declines, which may be linked to deteriorating recruitment. Because nest success is an important component of recruitment, understanding the influence of habitat on nest success is important for developing regional grouse management strategies. Therefore, our objectives were to determine grouse nest success rates, characterize nest site selection, and identify habitat characteristics associated with successful nests in this region. From 1995 to 2002, we located 234 nests, of which 147 (63%) were successful (≥1 egg hatched). We characterized habitat at 167 of these nests and compared successful and unsuccessful nests using logistic regression and Akaike's Information Criterion (AIC). Similarly, we characterized nest site selection by pairing 73 nests with 1–8 nearby systematic sites and conducting a matched-pairs logistic regression followed by AIC. Eleven of 25 candidate models of nest success were supported; distance to a road or opening, ground cover, deciduous canopy cover, coarse woody debris, and basal area were increasingly important predictors of nest success. Increases in basal area, coarse woody debris, and deciduous canopy cover improved the odds of nest success. Alternatively, greater amounts of ground cover and increased distance to a road or opening decreased the odds of a nest being successful. The two supported models of habitat selection were basal area with coarse woody debris and basal area alone. Odds of a habitat being selected increased with both variables. Selection of these habitat elements likely reflects the tendency for females to nest at the base of large trees, stumps, or logs, which can reduce their exposure to predators and seems to improve nest success. Increased ground cover may reduce the female's ability to detect a predator and increase the susceptibility of a nest. We recommend managers ensure coarse woody debris is available for nest sites, particularly when logging operations (e.g., clearcuts, thinnings) remove a high proportion of the standing basal area.

Clinical, biochemical, and sonographic evaluation of the remaining kidney function and size was performed in 34 patients, 12 males and 22 females, ages 2.1–19.6 years, nephrectomized for Wilms' tumor at least 2 years before (mean 8.6). All patients had normal blood pressure and serum bicarbonates. Two of them had microhematuria, four proteinuria 4 mg/m2/hr, and 11 microalbuminuria (MA) >20 mg/24 hr. Only one patient had reduced creatinine clearance and maximum bipolar length (MBL) as well as kidney volume (KV)

The 77 Se, 13 C and 1 H NMR spectra of the products of phenylselenenyl azide and chloride addition to methylenecyclohexane and cyclohexene are presented. Scalar coupling between 77 Se and 1 H/ 13 C allowed the absolute assignment of the regioisomers in the 1 H and 13 C spectra. Low-temperature 77 Se NMR was used to determine the conformer ratios for 1-azidomethyl- and 1-chloromethyl-1-phenylselenenylcyclohexane anti-Markovnikov addition products

The addition of phenylselenenyl azide to glycals is carried out under conditions that give 2-deoxy-2-phenylselenoglycosyl azides. This regiochemistry is opposite to that obtained under free-radical conditions, which are known to produce 2-azido-2-deoxyselenoglycosides. The addition reaction is carried out with phenylselenenyl chloride and sodium azide in dimethylformamide, and is stereoselective for trans addition. Tri-O-benzyl-d-glucal and di-O-benzyl-l-rhamnal each gave two addition products, in which the phenylselenyl and azido groups were either trans diaxial or trans diequatorial. Tri-O-benzyl-d-galactal gave only the trans diaxial addition product.

New procedures are described for the cyclization of allylic 1, 1-dimethylisoureas. Efficient cyclization of the isoureas to give substituted oxazolines occurs with both N-iodosuccinimide and phenylselenenyl triflate. Reductive dehalogenation can be carried out with lithium aluminum hydride.

The branched-chain nitro sugar methyl 2,3,6-trideoxy-3-C-methyl-3-nitro-α-D-ribo-hexopyranoside 4 was investigated as a precursor to D-rubranitrose, a nitro sugar found in the antibiotic rubradirin. X-ray cyrstallographic analysis of 4 shows that the pyranose ring adopts the 4 C 1 conformation with the methoxy group at C-1 and the nitro group at C-3 in a 1,3-diaxial relationship. There is an intermolecular hydrogen bond involving a nitro group oxygen of one monosaccharide residue and the C-4 hydroxyl group of the adjacent residue in the crystal lattice. This interaction results in a helical crystal packing. A series of nucleophilic displacement reactions was carried out on the triflate derivative of 4 in an attempt to introduce an axial carbon-oxygen bond at C-4 required for rubranitrose. Displacements with acetate and propionate gave as products the monosaccharide esters with the desired D-xylo configuration.

Derivatives of the branched amino sugar methyl 3-amino-2,3,6-trideoxy-3-C-methyl-α-L-ribo-hexopyranoside and its 3-nitro analog were coupled with glycosyl donors of 3,4-di-O-acetyl-2,6-dideoxy-L-fucopyranose. Successful glycosylations were developed using the fucosyl bromide, activated with silver triflate, and the fucosyl oxysilane, activated with trimethylsilyl triflate. High stereoselectivities for the desired α-1,4 linkage were observed in both cases. The N-trifluoroacetamido disaccharide was deacylated and the amino group oxidized to nitro with dimethyldioxirane. An alternate route based on coupling of the fucosyl bromide with the nitro sugar methyl α-L-decilonitroside also gave the α-linked disaccharide, which is related to oligosaccharides found in the antibiotics cororubicin and arugomycin.

The synthesis of callipeltose, a novel amino sugar with the proposed structure, 4-amino-4,6-dideoxy-2, O -3- C -dimethyl- l -talopyranosyl-3,4-urethane, from l -rhamnose is described. Oxime reduction, carbamate cyclization and selective methylation are key steps. The synthesis supports the assignment of the relative stereochemistry of callipeltose.

The synthesis of methyl α- l -vancosaminide from di- O -acetyl- l -rhamnal is described. The allylic alcohol methyl 2,3,6-trideoxy-3- C -methyl-α- l - threo -hex-2-enopyranoside was prepared from the glycal, 1,5-anhydro-1,2,6-trideoxy-3- C -methyl- l - ribo -hex-1-enitol, and converted to its N , N -dimethylisourea derivative. The cis amino alcohol functionality in vancosamine was introduced by the electrophilic cyclization of the isourea, followed by hydrolysis of the resulting oxazoline.

The addition of benzenesulfinic acid to glycals was investigated under various conditions, and optimized yields of the glycosyl phenylsulfone products were obtained in the presence of tin tetrachloride as a catalyst. Double bond shift (Ferrier rearrangement) occurred in all cases except amicetal, which lacks a substituent at the allylic carbon. Glycosylation of benzenesulfinic acid with 1,2-dibromides was carried out using silver triflate as the promoter, and gave sulfinate esters as products by reaction at oxygen rather than at sulfur. The sulfinate esters were obtained as mixtures of stereoisomers at the stereogenic sulfur atom. Trapping of the sulfinates with carboxylate nucleophiles was observed during attempted oxidation with MCPBA.

Reaction of alkenes and alkenols with N-iodosuccinimide (NIS) and benzenesulfinic acid in dichloromethane at room temperature affords vic-iodophenylsulfonyl adducts in good to high yields. Treatment of the iodosulfones with neutral alumina in dichloromethane at room temperature results in dehydroiodination to give the corresponding vinyl sulfones in high yield and purity by this convenient two-step procedure. Application of the iodosulfonation–dehydroiodination sequence to allylic alcohols and silyl ethers gave γ-oxygenated, α,β-unsaturated phenylsulfones, while the attempted iodosulfonation of glycals, as intermediates to vinyl sulfones, resulted in addition of benzenesulfinic acid with double bond shift (Ferrier rearrangement). Key words: iodosulfonation, vinyl sulfones, benzenesulfinic acid, N-iodosuccinimide, dehydroiodination.

A method for the preparation of C-methyl branched nitro sugars from the corresponding amino sugars by oxidation with mixed oxidants is described. Ozonolysis of the amino sugars in the presence of OXONE (potassium monopersulfate) and acetone (Bashir-Hashemi's procedure) gave nitro sugars in good yields. Oxidation of an O-benzylhydroxylamino sugar by this method resulted in deprotection and oxidation in a single step, giving the nitro sugar directly. The mixed oxidant method is experimentally simpler and more convenient to use than DMDO, which had been previously reported for the oxidation of amino sugars.

Background Oral lichen planus (OLP) is an autoimmune disease of unknown aetiology. The pathogenesis is characterized by apoptosis of basal keratinocytes, triggered by contact between CD8+-activated lymphocytes and an unknown antigen expressed on the surface of the basal cells. Basement membrane (BM) degradation, which allows lymphocytes to migrate, involves proteolytic enzymes known as matrix metalloproteinases (MMPs). Objectives This study aimed to evaluate the expression of a series of MMPs in biopsies from OLP patients, to reveal correlations with different clinical forms of OLP. Methods Twenty-six patients diagnosed with OLP (14 reticular and 12 erosive) were studied, together with seven healthy patients as negative controls. Results Reverse transcriptase polymerase chain reaction (RT-PCR) showed that the overall levels of expression of MMP mRNAs were higher in erosive lichen planus (E-OLP) than in the reticular forms (R-OLP). Moreover, MMP-1 and MMP-3 may be principally associated with erosion development. The expression of specific tissue inhibitors of metalloproteinases (TIMPs) was also evaluated. Conclusions The different clinical appearances of OLP are associated with significant differences in MMP mRNA levels.