Towards development of a fully synthetic conjugate vaccine: Investigation of structural analogs of \u3ci\u3eStreptococcus pneumoniae \u3c/i\u3e serogroup 6

Involvement of complex glycostructures in a variety of damaging and healing processes has already been acknowledged by development of carbohydrate-based vaccines and therapeutics. The bacteria Streptococcus pneumoniae (SPn) have become one of the most frequent causes of pneumonia, bacteremia, and meningitis in the elderly, immunocompromised, and, especially, in young children. SPn has one of the largest public health and economic impacts amongst all bacterial infectious diseases. Over 2 million children die annually worldwide due to pneumonia, accounting for almost 20% of deaths under age five with more than half of these deaths attributed to SPn. Amongst over ninety elucidated SPn serotypes, the SPn serogroup6 has been consistently ranked within the top three causes of invasive pneumococcal disease worldwide. The SPn bacterial cell is surrounded by a polysaccharide capsule and preventive vaccination is a viable tool against the bacterial invasion. Usually, serotype-specific antibodies are formed in response. Synthetic oligosaccharide components can be conjugated to a carrier protein with conventional coupling chemistry, to obtain semi-synthetic conjugate vaccines (glycoconjugates). This doctoral dissertation describes the application of a new glycosylation method for the synthesis of glycostructures to study immunological properties of serogroup 6. The development of an expeditious strategy to obtain synthetic saccharides of SPn6 and glycoconjugates thereof will ensure reliable and reproducible immunological studies. Consequently, by identifying the immunogenic responses of these glycoconjugates, will help target toward the development of effective vaccine candidates against SPn

In vivo imaging of epileptic activity using 2-NBDG, a fluorescent deoxyglucose analog

Accurately locating epileptic foci has great importance in advancing the treatment of epilepsy. In this study, epileptic seizures were first induced by intracortical injection of 4-aminopyridine in rats. A fluorescent deoxyglucose substitute, 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG), was then continuously injected via the tail vein. Brain glucose metabolism was subsequently monitored by fluorescence imaging of 2-NBDG. The initial uptake rate of 2-NBDG at the injection site of 4-aminopyridine significantly exceeded that of the control injection site, which indicated local hypermetabolism induced by seizures. Our results show that 2-NBDG can be used for localizing epileptic foci

In vivo imaging of epileptic activity using 2-NBDG, a fluorescent deoxyglucose analog

Accurately locating epileptic foci has great importance in advancing the treatment of epilepsy. In this study, epileptic seizures were first induced by intracortical injection of 4-aminopyridine in rats. A fluorescent deoxyglucose substitute, 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG), was then continuously injected via the tail vein. Brain glucose metabolism was subsequently monitored by fluorescence imaging of 2-NBDG. The initial uptake rate of 2-NBDG at the injection site of 4-aminopyridine significantly exceeded that of the control injection site, which indicated local hypermetabolism induced by seizures. Our results show that 2-NBDG can be used for localizing epileptic foci

Experimental and theoretical study of the structures and enthalpies of formation of the synthetic reagents l,3-thiazolidine-2-thione and l,3-oxazolidine-2-thione

This paper reports an experimental and a theoretical study of the structures and standard (po = 0.1 MPa) molar enthalpies of formation of the synthetic reagents 1,3-thiazolidine-2-thione [CAS 96-53-7] and 1,3-oxazolidine-2-thione [CAS 5840-81-3]. The enthalpies of combustion and sublimation were measured by rotary bomb combustion calorimetry, and the Knudsen effusion technique and gas-phase enthalpies of formation values at T = 298.15 K of (97.1 ± 4.0) and −(74.4 ± 4.6) kJ·mol−1 for 1,3-thiazolidine-2-thione and 1,3-oxazolidine-2-thione, respectively, were determined. G3-calculated enthalpies of formation are in reasonable agreement with the experimental values. In the solid state, 1,3-thiazolidine-2-thione exists in two polymorphic forms (monoclinic and triclinic) and 1,3-oxazolidine-2-thione exits in the triclinic form. The isostructural nature of these compounds and comparison of their molecular and crystal structures have been analyzed. The experimental X-ray powder diffractograms have been compared with the calculated patterns from their structures for identification of the polymorphic samples used in this study. A comparison of our results with literature thermochemical and structural data for related compounds is also reported.M.T. would like to thank MEC/SEUI, FPU AP2002-0603, Spain, for financial support. A.V.D. thanks the National Science Foundation (CHE-0547566) and the American Heart Association (0855743G) for financial support of this research. The support of the Spanish Ministerio de Educación y Ciencia under Projects CTQ2007-60895/BQU and CTQ2006-10178/BQU is gratefully acknowledged

Experimental and Theoretical Study of the Structures and Enthalpies of Formation of the Synthetic Reagents 1,3-Thiazolidine-2-thione and 1,3-Oxazolidine-2-thione

This paper reports an experimental and a theoretical study of the structures and standard (p o ) 0.1 MPa) molar enthalpies of formation of the synthetic reagents 1,3-thiazolidine-2-thione and 1,3-oxazolidine-2-thione . The enthalpies of combustion and sublimation were measured by rotary bomb combustion calorimetry, and the Knudsen effusion technique and gas-phase enthalpies of formation values at T ) 298.15 K of (97.1 ( 4.0) and -(74.4 ( 4.6) kJ · mol -1 for 1,3-thiazolidine-2-thione and 1,3-oxazolidine-2-thione, respectively, were determined. G3-calculated enthalpies of formation are in reasonable agreement with the experimental values. In the solid state, 1,3-thiazolidine-2-thione exists in two polymorphic forms (monoclinic and triclinic) and 1,3-oxazolidine-2-thione exits in the triclinic form. The isostructural nature of these compounds and comparison of their molecular and crystal structures have been analyzed. The experimental X-ray powder diffractograms have been compared with the calculated patterns from their structures for identification of the polymorphic samples used in this study. A comparison of our results with literature thermochemical and structural data for related compounds is also reported

Identification of a Simple Chemical Structure Associated with Protective Human Antibodies against Multiple Pneumococcal Serogroups▿

Streptococcus pneumoniae, a major human pathogen, expresses at least 91 serologically distinct carbohydrate capsules. Since pneumococcal vaccines are designed to elicit antibodies against many different capsular polysaccharides (PSs), it is important to identify the epitopes involved in eliciting anti-capsular PS antibodies. We investigated the epitopes recognized by Dob1, which is a hybridoma-secreting human immunoglobulin G2 antibody to the PS of serotype 6B (Y. Sun et al., Infect. Immun. 67:1172-1179, 1999). We found that Dob1 bound synthetic capsular carbohydrates Gal(1→3)α-d-Glcp(1→3)α-l-Rhap(1→3)Rib-ol and α-d-Glcp(1→3)α-l-Rhap(1→3)Rib-ol but did not bind α-l-Rhap(1→3)Rib-ol. The critical epitope α-d-Glcp(1→3)α-l-Rhap is found in the capsular PSs of serotypes 6A, 6B, 6C, and 19A but not in the 19F PS. Consistent with this observation, Dob1 bound to the PSs of serotypes 6A, 6B, 6C, and 19A but did not bind the 19F PS and 23 additional unrelated pneumococcal capsular PSs. Also, Dob1 could opsonize pneumococci expressing serotypes 6A, 6B, 6C, and 19A but did not opsonize 19F pneumococci. In addition, ca. 7% of immune sera (12 of 175 sera) had significant amounts of Dob1-like antibodies, i.e., reacted with 6B and 19A PSs, but not with 19F PS. Humans can produce antibodies to the Dob1 epitope and the antibodies to that epitope cross-react with the four serotypes 6A, 6B, 6C, and 19A that belong to different serogroups. This epitope may be useful for producing a totally synthetic, simple chemical structure that is capable of generating protective antibodies to multiple pneumococcal serogroups

Thermophysical properties in medium temperature range of several thio and dithiocarbamates

The present study reports a DSC study of the thio-and dithiocarbamates: 3H-benzoxazole-2-thione (2-mercaptobenzoxazole), 3H-benzothiazole-2-thione (2-mercaptobenzothiazole), thiazolidine-2-thione (2-mercapto-2-thiazoline), oxazolidine-2-thione (2-mercapto-2-oxazoline) and tetrahydro-1,3-oxazine-2-thione (5,6-dihydro-4H-1,3-oxazine-2-thiol) in the temperature interval T=268 K and the melting temperatures. Temperatures, enthalpies and entropies of fusion are reported. No solid-solid phase transitions were observed for the compounds in the temperature interval studied. The heat capacity of the compounds as a function of temperature was measured.We acknowledge the Spanish MCyT/DGI under project BTQ2006-12745. A. V. D. thanks National Institutes of General Medical Sciences (GM077170) for financial support of this research. M. T. thanks MEC/SEUI, AP2002-0603, Spain for financial support

Knowledge of a molecule: An experimental and theoretical study of the structure and enthalpy of formation of tetrahydro-2 H -1,3-oxazine-2-thione

In a continuation of our investigations of the thermochemistry of heterocyclic ring systems and sulfur-containing compounds, the standard molar enthalpy of formation of tetrahydro-2H-1,3-oxazine-2-thione (CAS no. 17374-18-4) at T = 298 K has been evaluated both experimentally and computationally. Combined enthalpies of combustion and sublimation, measured by rotary bomb combustion calorimetry and the Knudsen effusion technique, yielded a gas-phase enthalpy of formation of −(104.0 ± 5.5) kJ·mol–1. The G3 value of −104.6 kJ·mol–1 calculated using an isodesmic bond separation reaction is in excellent agreement with the experimental result. The variation in enthalpy of formation with ring size is discussed, and the G3 enthalpy of formation of tetrahydro-2H-1,3-thiazine-2-thione (72.4 kJ·mol–1) was also computed for this purpose.The support of the Spanish Ministerio de Ciencia e Innovación under Projects CTQ2007-60895/BQU and CTQ2010-16402 is gratefully acknowledged. M.T. acknowledges the Spanish Ministry of Science and Innovation for a “Juan de la Cierva” Contract