Kryptoracemates

Racemic crystals normally crystallise in centrosymmetric spacegroups containing equal numbers of enantiomers. More rarely, racemates may crystallise in non-centrosymmetric space-groups having glide symmetry or, even more rarely, in space-groups devoid of a centre of inversion, having no rotary-inversion axes nor glide plane. The latter class of crystals form the subject of the present bibliographic review – a survey of kryptoracemic behaviour. The term kryptoracemic alludes to the presence of a hidden or non-crystallographic centre of inversion between two molecules that might otherwise be expected to crystallise in an achiral space-group, often about a centre of inversion. Herein, examples of molecules with stereogenic centres crystallising in one of the 65 Sohncke space-groups are described. Genuine kryptoracemates, i.e. crystals comprising only enantiomorphous pairs are described followed by an overview of non-genuine kryptoracemates whereby the crystal also contains other species such as solvent and/or counterions. A full range, i.e. one to six, stereogenic centres are noted in genuine kryptoracemates. Examples will also be described whereby there are more that one enantiomeric pair of molecules in the crystallographic asymmetric unit. A more diverse range of examples are available for non-genuine kryptoracemates. There are unbalanced species where in addition to the enantiomeric pair of molecules, there is another enantiomeric molecule present. There are examples of genuine co-crystals, solvated species and of salts. Finally, special examples will be highlighted where the counterions are chiral and where they are disparate, both circumstances promoting kryptoracemic behaviour

Adherence with American Academy of Pediatrics guidelines when managing neonatal jaundice in Jordan

Mohammad Khassawneh,1 Ziad Rubaie,2 Issa Khashashneh,3 Fakhri Makhlouf,4 Ahmed Alkafajei2 1Department of Pediatrics, 2Department of Public Health, Jordan University of Science and Technology; 3Department of Pediatrics, Prince Rashid Hospital; 4Department of Pediatrics, Princess Rahma Children's Hospital, Irbid, Jordan Background: Bilirubin encephalopathy is a significant health problem in developing countries. Understanding regional practices in comparison with international standards is needed to assess the safety and efficacy of our local management practice. Methods: This retrospective study included all neonates (≥35 weeks gestation) with hyperbilirubinemia who were admitted to the three main neonatal units in northern Jordan between January 2007 and January 2009. Demographic variables and risk factors were collected. Management of hyperbilirubinemia in the absence of national guidelines was compared with that recommended by the American Academy of Pediatrics. Results: Four hundred and sixteen infants were admitted with hyperbilirubinemia and received phototherapy. The phototherapy threshold was met in only 210 (50%) of infants. Seventy infants (17%) received exchange transfusion, and the threshold was met in 60 (86%) infants. Only 50% of infants who needed exchange transfusion received the procedure. Conclusion: Despite the high rate of unnecessary phototherapy, exchange transfusion was performed in one of every two infants who met the international criteria for the procedure. Studies are needed in our country to evaluate the impact of this practice on infants with hyperbilirubinemia. Keywords: neonatal jaundice, hyperbilirubinemia, exchange transfusion, guideline