Haemophagocytic lymphohistiocytosis (HLH) is a clinico-pathologic entity caused by increased proliferation
and activation of benign macrophages with haemophagocytosis throughout the reticulo-endothelial system.
Virus-associated HLH is a well-recognised entity. Although majority of parvovirus B19 associated HLH does not
require any specific treatment and carries good prognosis, outcome of children is worse than adults. We report
here a case of HLH associated with acute parvovirus B19 infection in a young healthy patient with underlying
hereditary spherocytosis, with bone marrow findings typical of parvovirus infection. Although this patient
had spontaneous recovery of cell counts, he succumbed due to complication from prolonged ventilation.
Unexpectedly, his immunoglobulin levels were inappropriately normal despite on-going ventilator associated
pneumonia, which reflects inadequate humoral immune response towards infection.
Polymer blending has been a facile method to resolve the brittle issue of poly(lactic acid) (PLA). Yet, miscibility becomes the primary concern that would affect the synergy effect of polymer blending. This study aimed to improve the miscibility of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) and PLA by lowering their molecular weights via a melt-blending-induced thermal degradation during mechanical mixing to form m-P34HB/PLA blends. The molecular weight of the P34HB was significantly reduced after blending, thereby improving the miscibility of the blends, as evidenced by the shift of glass transition temperatures. Also, simulation based on Flory-Huggins theory demonstrated increased miscibility with decreasing molecular weight of the polymers. Moreover, the thermal gravimetric analysis revealed that the PLA provided a higher shielding effect to the P34HB in the blends prepared by melt-blending than those by solution-blending, that the addition of PLA could retard the chain scission of P34HB and delay its degradation. The addition of m-P34HB at 20 wt% in the blend contributed to a 60-fold enhancement in the elongation at break and an increment of 4.6 folds in the Izod impact strength. The enzymatic degradation using proteinase K revealed the preferential to degrade the PLA in the blends and followed the surface erosion mechanism.