Morphological population balance modelling of the effect of crystallisation environment on the evolution of crystal size and shape of para-aminobenzoic acid

A current morphological population balance (MPB) modelling methodology, which integrates crystal morphology, facet growth kinetics with multi-dimensional population balance, is overviewed and demonstrated, hence providing an attractive approach for modelling crystallisation processes. MPB modelling is applied to simulate the batch crystallisation of the alpha-form of para-aminobenzoic acid from ethanolic solutions as a function of the crystallisation environment including cooling rate, seeding temperature and seed conditions (loading, size and shape). The evolution of crystal shape/size and their distributions revealed that higher loading led to smaller and less needle-like crystals with similar yields, hence potentially being an important parameter for process control. Examination of the development of the fracture surface for broken seeds, mimicking the seed conditions after milling in practice in the simulated processes, demonstrated that these faces grew fast and then rapidly disappeared from the external crystal morphology. Restriction and challenges inherent in the current model are also highlighted

Up Regulation of the Maternal Immune Response in the Placenta of Cattle Naturally Infected with Neospora caninum

Neospora caninum is an intracellular protozoan parasite which is a major cause of abortion in cattle worldwide. It forms persistent infections which recrudesce during pregnancy leading to foetal infection and in a proportion of cases, abortion. The mechanisms underlying abortion are not understood. In this study, recrudescence of a persistent infection in eight naturally infected cows occurred between 20 and 33 weeks of gestation. Animals were killed at the time of recrudescence and parasites were detected in the placentae and foetuses. An active maternal immune response consisting of an infiltration of CD4+ and CD8+ T cells and a 46–49 fold increase in interferon-γ and interleukin-4 mRNA was detected. Other cytokines, notably interleukin-12 p40, interleukin-10 and tumour necrosis factor-α were also significantly increased and Major Histocompatibility Class II antigen was expressed on maternal and foetal epithelial and stromal fibroblastoid cells. Significantly, despite the presence of an active maternal immune response in the placenta, all the foetuses were alive at the time of maternal euthanasia. There was evidence of parasites within foetal tissues; their distribution was restricted to the central nervous system and skeletal muscle and their presence was associated with tissue necrosis and a non-suppurative inflammatory response involving lymphocytes and macrophages, irrespective of the gestational age of the foetus. Whilst an active maternal immune response to a pathogen in the placenta is generally considered to be damaging to the foetal trophoblast, our findings suggest that the presence of a parasite-induced maternal immune response in the placenta is not detrimental to foetal survival but may contribute to the control of placental parasitosis

Supersaturation and solvent dependent nucleation of carbamazepine polymorphs during rapid cooling crystallization

Polymorphic nucleation behavior of carbamazepine (CBZ) was investigated in terms of supersaturation in several solvents: nitromethane, acetonitrile, acetone, ethanol, 2-propanol and toluene. The solubility was measured and the effects of interaction between the solvent and CBZ on solubility and polymorphic nucleation were discussed. It was found that the polymorphic forms of CBZ largely depended on the solvent type and supersaturation ratio. The carbonyl group in acetone blocked the NH⋯O interaction between the dimer in form II by mimicking the same interaction with CBZ, then favored the nucleation of form III. The aromatic–aromatic interaction between CBZ and the solvent like toluene decreased the solute–solute interaction and favored the formation of form II. The nucleation domains of CBZ polymorphs (forms II and III) were separated as a function of supersaturation ratio range in each solvent, and the effects of solvents and supersaturation ratios on the induction time and transformation process were also explored. The interfacial energies of forms II and III in different solvents were calculated, and it was found that, at all investigated supersaturation ratios, the interfacial energy of form II in all solvents except acetone was always lower than that of form III, indicating that nucleation kinetics preferably favored the formation of form II. However, at lower supersaturation ratios, thermodynamics was critical and form III was obtained

Ovine herpesvirus-2 encoded microRNAs target virus genes involved in virus latency

Herpesviruses encode miRNAs that target both virus and host genes; however their role in herpesvirus biology is poorly understood. We previously identified eight miRNAs encoded by OvHV-2; the causative agent of malignant catarrhal fever (MCF) and have now investigated the role of these miRNAs in regulating expression of OvHV-2 genes that play important roles in virus biology. ORF 20 (cell cycle inhibition), ORF 50 (reactivation) and ORF 73 (latency maintenance) each contain predicted targets for several OvHV-2 miRNAs. Co-transfection of miRNA mimics with luciferase reporter constructs containing the predicted targets showed the 5’ UTRs of ORF 20 and ORF 73 contain functional targets for ovhv-miR-2 and ovhv2-miR-8 respectively, and the 3’UTR of ORF 50 contains a functional target for ovhv2-miR-5. Transfection of BJ1035 cells (an OvHV-2 infected bovine T cell line) with the relevant miRNA mimic resulted in a significant decrease in ORF 50 and a smaller but non-significant decrease in ORF 20. However, we were unable to demonstrate a decrease in ORF 73. MCF is a disease of dysregulated lymphocyte proliferation, miRNA inhibition of ORF 20 expression may play a role in this aberrant lymphocyte proliferation. The proteins encoded by ORFs 50 and 73 play opposing roles in latency, it has been hypothesized that miRNA-induced inhibition of virus genes acts to ensure that fluctuations in virus mRNA levels do not result in reactivation in conditions that are unfavourable for viral replication, our data would support this hypothesis

The thermal expansion coefficients of the alpha and beta polymorphic forms of p-aminobenzoic acid in relation to their bulk crystal chemistry

The thermal expansion behaviour of the alpha and beta polymorphs of para-aminobenzoic acid are presented and discussed in terms of the bulk crystal chemistry and the associated strengths of the constituent intermolecular synthons for these two materials. Analysis of temperature dependant powder diffraction data over the temperature range 298.15–403.15 K facilitates calculation of the linear thermal expansion coefficients: αa = 8.36 × 10−06 K−1, αb = 94.5 × 10−06 K−1 and αc = 9.91 × 10−06 K−1 for the alpha polymorph and αa = 21.5 × 10−06 K−1, αb = 48.5 × 10−06 K−1 and αc = 2.22 × 10−06 K−1 for the beta polymorph. The exceptionally large increase in the thermal expansion of the b axis for the alpha form reflects the weak dispersive interactions which propagate along this axis. In contrast, the a and c axes contain relatively strong hydrogen bonds which stabilise the lattice and limit thermal expansion. The thermal expansion of the beta form reflects the more isotropic nature of the intermolecular synthons for this polymorph in comparison to the alpha form. The thermal expansion of the b axis of the beta form is larger than that of the a and c axes but to a much lesser extent than that observed for the alpha form. This is rationalised through identification of a hydrogen bonding component which contributes to the stabilisation of the b axis in comparison to the almost fully dispersive nature found in the alpha structure

Malignant Catarrhal Fever Induced by Alcelaphine herpesvirus 1 Is Associated with Proliferation of CD8+ T Cells Supporting a Latent Infection

Alcelaphine herpesvirus 1 (AlHV-1), carried by wildebeest asymptomatically, causes malignant catarrhal fever (WD-MCF) when cross-species transmitted to a variety of susceptible species of the Artiodactyla order. Experimentally, WD-MCF can be induced in rabbits. The lesions observed are very similar to those described in natural host species. Here, we used the rabbit model and in vivo 5-Bromo-2′-Deoxyuridine (BrdU) incorporation to study WD-MCF pathogenesis. The results obtained can be summarized as follows. (i) AlHV-1 infection induces CD8+ T cell proliferation detectable as early as 15 days post-inoculation. (ii) While the viral load in peripheral blood mononuclear cells remains below the detection level during most of the incubation period, it increases drastically few days before death. At that time, at least 10% of CD8+ cells carry the viral genome; while CD11b+, IgM+ and CD4+ cells do not. (iii) RT-PCR analyses of mononuclear cells isolated from the spleen and the popliteal lymph node of infected rabbits revealed no expression of ORF25 and ORF9, low or no expression of ORF50, and high or no expression of ORF73. Based on these data, we propose a new model for the pathogenesis of WD-MCF. This model relies on proliferation of infected CD8+ cells supporting a predominantly latent infection