Oldest evidence of tuberculosis in Argentina: A multidisciplinary investigation in an adult male skeleton from Saujil, Tinogasta, Catamarca (905-1030 CE).

The Mycobacterium tuberculosis complex (MTC) has affected South American populations since ca. 200 years BCE. In Argentina, possible cases date from ca. 1000-1400 Common Era (CE). This paper describes the oldest (905-1030 CE) confirmed case of tuberculosis (TB) in a young adult male from Lomitas de Saujil (Tinogasta, Catamarca, Argentina). Osteolytic lesions on the bodies of the lower spine were macroscopically and radiographically identified. Bilateral new bone formation was seen on the visceral vertebral third of several ribs and in long bones, compatible with hypertrophic osteoarthropathy. Representative rib and hand bones gave profiles for MTC-specific C27-C32 mycocerosic acid lipid biomarkers; these were strongest in one heavily-lesioned lower rib, which also had MTC-diagnostic C76-C89 mycolic acids and positive amplification of MTC-typical IS6110 aDNA fragments. During the first millennium CE, the intense social interaction, the spatial circumscription of villages among the pre-Hispanic societies in the mesothermal valleys of Catamarca and the fluid contacts with the Eastern lowlands, valleys and puna, were factors likely to favor disease transmission. It is proposed that TB arrived from northern Chile and dispersed towards the northeast into the Yocavil valley, where several cases of TB infection were macroscopically identified for a later chronology.

Photophysics and spectroscopic properties of 3-benzoxazol-2-yl-chromen-2-one.

The photophysics of 3-benzoxazol-2-yl-chromen-2-one was studied in different solvents. High molar absorptivities, between 14,800 and 22,900 dm3/mol cm, were observed for the absorption peak related to the S0 --> S1 transition which suggests a pi --> pi* character. This compound presents a limited solvatochromism, attributed to the benzoxazole group, and high fluorescence quantum yields, phi(f). The fluorescence quantum yield is lowered with the increase of solvent polarity, favouring the participation of internal conversion as deactivation path of the S1 state. The Stokes shift shows that the excited state is stabilised with increasing solvent polarity. The dipole moment was estimated by ab initio calculations as being between 5.28 and 5.62 Debye for S1, and 4.75 Debye for S0. Phosphorescence was not observed. A small but not negligible quantum yield of singlet oxygen generation (phidelta = 0.15) was measured in chloroform. The geometric parameters obtained by semi-empirical calculation (PM3) are in good agreement with crystallographic data, showing a r.m.s. deviation of 0.153 A for the superposition of both structures. The predicted structure is all planar, while the crystallographic data reveal a dihedral angle of 6.5 degrees, between the coumarin and benzoxazole rings. The theoretical description of the electronic spectra, obtained from a PM3 CI calculation, shows excellent agreement with the experimental data. Deviations lower than 2% are observed in the predicted absorption maxima, with best results when solvation is considered. For electronic states calculation, ZINDO/S gave a better prediction of excited state energies, with a deviation lower than 7% for the S1 energy. The most probable sequence for the first four excited states is: Ti(n pi*) < T2(pi pi*) < S1(pi pi*) < S2(n pi*).