A quaternary solid-form of ritonavir: an oxalate salt oxalic acid co-crystal acetone solvate

Ritonavir has been reported in seven crystal forms notably form I, II, IIIb and IV, as well as a hydrate, an L-tyrosine co-crystal and a formamide solvate. A new form is reported here with a novel quaternary structure with ritonavir as an oxalate salt, oxalic acid co-crystal and acetone solvate in a 1 : 1 : 0.5 : 0.5 stoichiometry. The new oxalate salt form (CCDC deposition number 2009282), was co-crystallised with oxalic acid from a supersaturated acetone solution, and exhibits a polar monoclinic crystal structure with a blocky needle-like crystal habit. The molecular conformation of ritonavir for the new form shows significant differences with respect to the well-characterised form I, II and IIIb polymorphs. Its crystallography is characterised by a 2-fold screw axis along the b axis, in a structure that exhibits multiple hydrogen bonds formed between amide–ureido, oxalate–oxalic acid and amide–amide groups in a layered intermolecular packing structure. Intermolecular stacking of the benzene and thiazole rings takes place along the crystallographic a axis with the needle axis growth of the crystals being likely to be governed by these interactions. The oxalate salt form co-crystal is found to have the characteristic conformations of the N-methyl urea and carbamate groups being in a trans and trans conformation respectively, as is the case for the recently discovered form IIIb, but in distinct contrast to cis and trans for form I, and trans and cis for form II. This may suggest that a cis and cis conformation for another new form may be feasible. The recovery of the form IV crystals at the lower concentrations of oxalic acid is perhaps indicative of its close similarity with the new oxalate salt co-crystal solvate form presented here

Relationship between Silent Gastroesophageal Reflux and Food Sensitization in Infants and Young Children with Recurrent Wheezing

It is known that early childhood wheezing associated with sensitization to allergens, including food, has an increased risk of developing asthma later during school age. Gastroesophageal reflux (GER) is well known to be associated with asthma. The purpose of this study was to determine whether there is an association between silent GER and food sensitization in infants and young children with recurrent wheezing. Eighty-five infants or young children with recurrent wheezing, and no gastrointestinal symptoms, underwent 24 hr esophageal pH monitoring, as well as total serum IgE and specific IgE testing for eggs and milk. Among the 85 subjects, 48.2% had significant GER. There was no significant difference in the GER between atopic and non-atopic recurrent wheezers (41.7% and 50.8%, respectively). The sensitization rate to food (eggs or milk) was 12.2% and 20.5% in the GER and non-GER groups, respectively and showed no statistically significant difference between the two groups (P=0.34). In conclusion, about half of infants and young children with recurrent wheezing and no gastrointestinal symptoms have silent GER. The silent GER may not contribute to food sensitization in infants and young children with recurrent wheezing

Understanding stress-induced disorder and breakage in organic crystals: beyond crystal structure anisotropy

Crystal engineering has advanced the strategies for design and synthesis of organic solids with the main focus being on customising the properties of the materials. Research in this area has a significant impact on large-scale manufacturing, as industrial processes may lead to the deterioration of such properties due to stress-induced transformations and breakage. In this work, we investigate the mechanical properties of structurally related labile multicomponent solids of carbamazepine (CBZ), namely the dihydrate (CBZ·2H2O), a cocrystal of CBZ with 1,4-benzoquinone (2CBZ·BZQ) and the solvates with formamide and 1,4-dioxane (CBZ·FORM and 2CBZ·DIOX, respectively). The effect of factors that are external (e.g. impact stressing) and/or internal (e.g. phase transformations and thermal motion) to the crystals are evaluated. In comparison to the other CBZ multicomponent crystal forms, CBZ·2H2O crystals tolerate less stress and are more susceptible to breakage. It is shown that this poor resistance to fracture may be a consequence of the packing of CBZ molecules and the orientation of the principal molecular axes in the structure relative to the cleavage plane. It is concluded, however, that the CBZ lattice alone is not accountable for the formation of cracks in the crystals of CBZ·2H2O. The strength and the temperature-dependence of electrostatic interactions, such as hydrogen bonds between CBZ and coformer, appear to influence the levels of stress to which the crystals are subjected that lead to fracture. Our findings show that the appropriate selection of coformer in multicomponent crystal forms, targetting superior mechanical properties, needs to account for the intrinsic stress generated by molecular vibrations and not solely by crystal anisotropy. Structural defects within the crystal lattice, although highly influenced by the crystallisation conditions and which are especially difficult to control in organic solids, may also affect breakage

Spatio-temporal Models of Lymphangiogenesis in Wound Healing

Several studies suggest that one possible cause of impaired wound healing is failed or insufficient lymphangiogenesis, that is the formation of new lymphatic capillaries. Although many mathematical models have been developed to describe the formation of blood capillaries (angiogenesis), very few have been proposed for the regeneration of the lymphatic network. Lymphangiogenesis is a markedly different process from angiogenesis, occurring at different times and in response to different chemical stimuli. Two main hypotheses have been proposed: 1) lymphatic capillaries sprout from existing interrupted ones at the edge of the wound in analogy to the blood angiogenesis case; 2) lymphatic endothelial cells first pool in the wound region following the lymph flow and then, once sufficiently populated, start to form a network. Here we present two PDE models describing lymphangiogenesis according to these two different hypotheses. Further, we include the effect of advection due to interstitial flow and lymph flow coming from open capillaries. The variables represent different cell densities and growth factor concentrations, and where possible the parameters are estimated from biological data. The models are then solved numerically and the results are compared with the available biological literature.Comment: 29 pages, 9 Figures, 6 Tables (39 figure files in total

Crude Oil-Degradation and Plasmid Profile of Nitrifying Bacteria Isolated from Oil-Impacted Mangrove Sediment in the Niger Delta of Nigeria

The crude oil degradability and plasmid profile of autotrophic nitrifying bacteria, Nitrosomonas and Nitrobacter species, isolated from mangrove sediment in the Niger Delta of Nigeria were studied. The effects of temperature, pH and optical density on the utilization of different carbon sources by the bacteria were also investigated. Results showed that nitrifying bacteria could utilize kerosene, diesel oil, jet fuel and engine oil as carbon sources. None utilized hexane and xylene but moderate growth was observed in benzene, phenol and toluene. However, their ability to utilized crude oil varied both in rates of utilization and in growth profiles. Mixed culture of the isolates degrades 52 % of crude oil introduced into the medium followed by Nitrosomonas sp. with 40 % degradation. The least was Nitrobacter sp. with 20 % degradation. The ability of the autotrophs to degrade crude oil was found to be plasmid-mediated through curing experiment and electrophoresis. The size of the plasmid involved was estimated to be 23 kb. The high crude oil utilization of the mixed culture implies that nitrifying bacteria isolated from contaminated ecosystem are excellent crude oil degraders and can be harnessed for bioremediation purposes

Institutional capacity for health systems research in East and Central African schools of public health: experiences with a capacity assessment tool

BACKGROUND: Despite significant investments in health systems research (HSR) capacity development, there is a dearth of information regarding how to assess HSR capacity. An alliance of schools of public health (SPHs) in East and Central Africa developed a tool for the self-assessment of HSR capacity with the aim of producing institutional capacity development plans. METHODS: Between June and November 2011, seven SPHs across the Democratic Republic of Congo, Ethiopia, Kenya, Rwanda, Tanzania, and Uganda implemented this co-created tool. The objectives of the institutional assessments were to assess existing capacities for HSR and to develop capacity development plans to address prioritized gaps. A mixed-method approach was employed consisting of document analysis, self-assessment questionnaires, in-depth interviews, and institutional dialogues aimed at capturing individual perceptions of institutional leadership, collective HSR skills, knowledge translation, and faculty incentives to engage in HSR. Implementation strategies for the capacity assessment varied across the SPHs. This paper reports findings from semi-structured interviews with focal persons from each SPH, to reflect on the process used at each SPH to execute the institutional assessments as well as the perceived strengths and weaknesses of the assessment process. Results The assessment tool was robust enough to be utilized in its entirety across all seven SPHs resulting in a thorough HSR capacity assessment and a capacity development plan for each SPH. Successful implementation of the capacity assessment exercises depended on four factors: (i) support from senior leadership and collaborators, (ii) a common understanding of HSR, (iii) adequate human and financial resources for the exercise, and (iv) availability of data. Methods of extracting information from the results of the assessments, however, were tailored to the unique objectives of each SPH. Conclusions This institutional HSR capacity assessment tool and the process for its utilization may be valuable for any SPH. The self-assessments, as well as interviews with external stakeholders, provided diverse sources of input and galvanized interest around HSR at multiple levels.DFI

Interferon Gamma-Dependent Intestinal Pathology Contributes to the Lethality in Bacterial Superantigen-Induced Toxic Shock Syndrome

Toxic shock syndrome (TSS) caused by the superantigen exotoxins of Staphylococcus aureus and Streptococcus pyogenes is characterized by robust T cell activation, profound elevation in systemic levels of multiple cytokines, including interferon-γ (IFN-γ), followed by multiple organ dysfunction and often death. As IFN-γ possesses pro- as well as anti-inflammatory properties, we delineated its role in the pathogenesis of TSS. Antibody-mediated in vivo neutralization of IFN-γ or targeted disruption of IFN-γ gene conferred significant protection from lethal TSS in HLA-DR3 transgenic mice. Following systemic high dose SEB challenge, whereas the HLA-DR3.IFN-γ+/+ mice became sick and succumbed to TSS, HLA-DR3.IFN-γ−/− mice appeared healthy and were significantly protected from SEB-induced lethality. SEB-induced systemic cytokine storm was significantly blunted in HLA-DR3.IFN-γ−/− transgenic mice. Serum concentrations of several cytokines (IL-4, IL-10, IL-12p40 and IL-17) and chemokines (KC, rantes, eotaxin and MCP-1) were significantly lower in HLA-DR3.IFN-γ−/− transgenic mice. However, SEB-induced T cell expansion in the spleens was unaffected and expansion of SEB-reactive TCR Vβ8+ CD4+ and CD8+ T cells was even more pronounced in HLA-DR3.IFN-γ−/− transgenic mice when compared to HLA-DR3.IFN-γ+/+ mice. A systematic histopathological examination of several vital organs revealed that both HLA-DR3.IFN-γ+/+ and HLA-DR3.IFN-γ−/− transgenic mice displayed comparable severe inflammatory changes in lungs, and liver during TSS. Remarkably, whereas the small intestines from HLA-DR3.IFN-γ+/+ transgenic mice displayed significant pathological changes during TSS, the architecture of small intestines in HLA-DR3.IFN-γ−/− transgenic mice was preserved. In concordance with these histopathological changes, the gut permeability to macromolecules was dramatically increased in HLA-DR3.IFN-γ+/+ but not HLA-DR3.IFN-γ−/− mice during TSS. Overall, IFN-γ seemed to play a lethal role in the immunopathogenesis of TSS by inflicting fatal small bowel pathology. Our study thus identifies the important role for IFN-γ in TSS

The Therapeutic effect of Memantine through the Stimulation of Synapse Formation and Dendritic Spine Maturation in Autism and Fragile X Syndrome

Although the pathogenic mechanisms that underlie autism are not well understood, there is evidence showing that metabotropic and ionotropic glutamate receptors are hyper-stimulated and the GABAergic system is hypo-stimulated in autism. Memantine is an uncompetitive antagonist of NMDA receptors and is widely prescribed for treatment of Alzheimer's disease treatment. Recently, it has been shown to improve language function, social behavior, and self-stimulatory behaviors of some autistic subjects. However the mechanism by which memantine exerts its effect remains to be elucidated. In this study, we used cultured cerebellar granule cells (CGCs) from Fmr1 knockout (KO) mice, a mouse model for fragile X syndrome (FXS) and syndromic autism, to examine the effects of memantine on dendritic spine development and synapse formation. Our results show that the maturation of dendritic spines is delayed in Fmr1-KO CGCs. We also detected reduced excitatory synapse formation in Fmr1-KO CGCs. Memantine treatment of Fmr1-KO CGCs promoted cell adhesion properties. Memantine also stimulated the development of mushroom-shaped mature dendritic spines and restored dendritic spine to normal levels in Fmr1-KO CGCs. Furthermore, we demonstrated that memantine treatment promoted synapse formation and restored the excitatory synapses to a normal range in Fmr1-KO CGCs. These findings suggest that memantine may exert its therapeutic capacity through a stimulatory effect on dendritic spine maturation and excitatory synapse formation, as well as promoting adhesion of CGCs

Intermittent Hypoxia-Induced Cognitive Deficits Are Mediated by NADPH Oxidase Activity in a Murine Model of Sleep Apnea

Background: In rodents, exposure to intermittent hypoxia (IH), a hallmark of obstructive sleep apnea (OSA), is associated with neurobehavioral impairments, increased apoptosis in the hippocampus and cortex, as well as increased oxidant stress and inflammation. Excessive NADPH oxidase activity may play a role in IH-induced CNS dysfunction. Methods and Findings: The effect of IH during light period on two forms of spatial learning in the water maze and well as markers of oxidative stress was assessed in mice lacking NADPH oxidase activity (gp91phox _/Y) and wild-type littermates. On a standard place training task, gp91phox _/Y displayed normal learning, and were protected from the spatial learning deficits observed in wild-type littermates exposed to IH. Moreover, anxiety levels were increased in wild-type mice exposed to IH as compared to room air (RA) controls, while no changes emerged in gp91phox _/Y mice. Additionally, wild-type mice, but not gp91phox _/Y mice had significantly elevated levels of NADPH oxidase expression and activity, as well as MDA and 8-OHDG in cortical and hippocampal lysates following IH exposures. Conclusions: The oxidative stress responses and neurobehavioral impairments induced by IH during sleep are mediated, at least in part, by excessive NADPH oxidase activity, and thus pharmacological agents targeting NADPH oxidase may provid