Rifampicin and protein concentrations in paired spinal versus ventricular cerebrospinal fluid samples of children with tuberculous meningitis

BACKGROUND

Tuberculous meningitis (TBM) is the most lethal form of TB. To study the disease, drug concentrations in samples obtained from the spinal CSF are usually used to reflect brain concentrations. Emerging data suggest that transport of substances across capillaries in the brain (ventricular CSF) and spinal cord may differ.

METHODS

We examined paired, time-linked samples of ventricular CSF (VCSF) and lumbar CSF (LCSF) of 28 patients with TBM and analysed these for rifampicin and total protein concentrations. Clinically indicated samples from procedures to determine the level of CSF block were collected from children being treated for TBM and hydrocephalus. Total protein concentrations were determined using the bicinchoninic acid (BCA) or turbidimetry assay, and rifampicin concentrations were determined using a validated LC coupled with tandem MS method. A paired Wilcoxon signed-rank test was used to determine significance.

RESULTS

TBM was confirmed in 19 cases (68%) using TB culture or GeneXpert Mtb/Rifampicin assay. All other cases were classified as probable. The median total protein concentration in LCSF was 6.0 g/L and in VCSF was 1.3 g/L. The median rifampicin concentration in LCSF was 299 ng/mL and 133 ng/mL in VCSF. The median ratio of LCSF/VSCF for protein was 4.23 and 1.57 for rifampicin.

CONCLUSIONS

Total protein and rifampicin concentrations differed significantly between the two compartments, both being higher in LCSF than in VCSF samples (P < 0.0001 for total protein and P = 0.0046 for rifampicin). Further studies are required to explore the causative reasons for the observed differences.

The influence of fixation and cryopreservation of cerebrospinal fluid on antigen expression and cell percentages by flow cytometric analysis

The pauci-cellular nature of cerebrospinal (CSF), particularly ventricular CSF, and the rapid cell death following sampling, incumbers the use of flow cytometric analysis of these samples in the investigation of central nervous system (CNS) pathologies. Developing a method that allows long-term storage and batched analysis of CSF samples without compromising cell integrity is highly desirable in clinical research, given that CSF is often sampled after hours creating logistical difficulties for fresh processing. We examined percentages and relative proportion of peripheral and brain-derived immune cells in cryopreserved and transfix-treated CSF, compared to freshly processed CSF. Cell proportions were more comparable between Fresh and Cryopreserved CSF (mean of differences = 3.19), than between fresh and transfix-treated CSF (mean of differences = 14.82). No significant differences in cell percentages were observed in fresh versus cryopreserved CSF; however significantly lower cell percentages were observed in transfix-treated CSF compared to Fresh CSF [(CD11b++ (p = 0.01), CD4+ (p = 0.001), CD8+ (p = 0.007), NK cells (p = 0.04), as well as CD69+ activation marker (p = 0.001)]. Furthermore, loss of marker expression of various lymphocyte sub-populations were observed in transfix-treated CSF. Cryopreservation is a feasible option for long-term storage of ventricular CSF and allows accurate immunophenotyping of peripheral and brain-derived cell populations by flow cytometry.

Blood-stage antimalarial activity, favourable metabolic stability and in vivo toxicity of novel piperazine linked 7-chloroquinoline-triazole conjugates

The persistence of drug resistance poses a significant obstacle to the advancement of efficacious malaria treatments. The remarkable efficacy displayed by 1,2,3-triazole-based compounds against Plasmodium falciparum highlights the potential of triazole conjugates, with diverse pharmacologically active structures, as potential antimalarial agents. We aimed to synthesize 7-dichloroquinoline-triazole conjugates and their structure-activity relationship (SAR) derivatives to investigate their anti-plasmodial activity. Among them, QP11, featuring a m-NO2 substitution, demonstrated efficacy against both chloroquine-sensitive and -resistant parasite strains. QP11 selectively inhibited FP2, a cysteine protease involved in hemoglobin degradation, and showed synergistic effects when combined with chloroquine. Additionally, QP11 hindered hemoglobin degradation and hemozoin formation within the parasite. Metabolic stability studies indicated high stability of QP11, making it a promising antimalarial candidate. In vivo evaluation using a murine malaria model demonstrated QP11's efficacy in eradicating parasite growth without neurotoxicity, presenting it as a promising compound for novel antimalarial development.

Antimicrobial evaluation of neutral and cationic iridium(III) and rhodium(III) aminoquinoline-benzimidazole hybrid complexes

A series of neutral and cationic Ir(III) and Rh(III) aminoquinoline-benzimidazole hybrid complexes were synthesised and their inhibitory activities evaluated against Plasmodium falciparum and Mycobacterium tuberculosis. In general, the hybrid complexes display good activity against the chloroquine-sensitive NF54 strain of P. falciparum. The neutral Ir(III)- and Rh(III)-Cp∗ complexes were the most active (IC₅₀ = 0.488 μM for Ir^III), maintaining activity against the multidrug-resistant K1 strain. Low to no cytotoxicity against the Chinese hamster ovarian cell line was observed for the tested complexes. Selected active hybrid complexes demonstrated significant inhibition of β-haematin formation in a cell-free NP-40 assay, suggesting an effect on the host haemoglobin degradation pathway as a potential contributing mechanism of action. When tested against M. tuberculosis H37Rv, most hybrid complexes displayed moderate to good activity. Again, the neutral complexes outperformed the cationic complexes, with the neutral Ir(III)-Cp∗ complexes proving most active (MIC₉₀ = 0.488-1.490 μM).

Synthesis and biological evaluation of novel quinoline-piperidine scaffolds as antiplasmodium agents

The parasitic disease malaria places almost half of the world's population at risk of infection and is responsible for more than 400,000 deaths each year. The first-line treatment, artemisinin combination therapies (ACT) regimen, is under threat due to emerging resistance of Plasmodium falciparum strains in e.g. the Mekong delta. Therefore, the development of new antimalarial agents is crucial in order to circumvent the growing resistance. Chloroquine, the long-established antimalarial drug, still serves as model compound for the design of new quinoline analogues, resulting in numerous new active derivatives against chloroquine-resistant P. falciparum strains over the past twenty years. In this work, a set of functionalized quinoline analogues, decorated with a modified piperidine-containing side chain, was synthesized. Both amino- and (aminomethyl)quinolines were prepared, resulting in a total of 18 novel quinoline-piperidine conjugates representing four different chemical series. Evaluation of their in vitro antiplasmodium activity against a CQ-sensitive (NF54) and a CQ-resistant (K1) strain of P. falciparum unveiled highly potent activities in the nanomolar range against both strains for five 4-aminoquinoline derivatives. Moreover, no cytotoxicity was observed for all active compounds at the maximum concentration tested. These five new aminoquinoline hit structures are therefore of considerable value for antimalarial research and have the potency to be transformed into novel antimalarial agents upon further hit-to-lead optimization studies.

Design and synthesis of novel ferrocene-quinoline conjugates and evaluation of their electrochemical and antiplasmodium properties

The tropical disease malaria is responsible for more than 400,000 deaths annually, especially in Southeast Asia and Africa. Although the number of malaria cases is declining, there still is an urgent need for novel antimalarial agents. The emergence of hybrid antimalarial agents and the precedence set by the antimalarial drug ferroquine (FQ) prompted us to design new ferrocene-containing quinoline structures. Herein, we report the efficient synthesis of three different series of ferrocene-quinoline conjugates and a class of ferrocene-containing heterotricycles in good to high yields. For all twenty novel ferrocenyl derivatives, electrochemical properties were investigated using cyclic voltammetry and antiplasmodium evaluation against a chloroquine-susceptible NF54 strain of the human malaria parasite Plasmodium falciparum was conducted, pointing to three compounds showing submicromolar potency. Subsequently, cytotoxicity assays against a Chinese Hamster Ovarian cell line and evaluation against a chloroquine-resistant strain of Plasmodium falciparum for these three compounds revealed selective and promising antiplasmodium activity.

Linkage analysis of candidate regions using a composite neurocognitive phenotype correlated with schizophrenia

As schizophrenia is genetically and clinically heterogeneous, systematic investigations are required to determine whether ICD-10 or DSM-IV categorical diagnoses identify a phenotype suitable and sufficient for genetic research, or whether correlated phenotypes incorporating neurocognitive performance and personality traits provide a phenotypic characterisation that accounts better for the underlying variation. We utilised a grade of membership (GoM) model (a mathematical typology developed for studies of complex biological systems) to integrate multiple cognitive and personality measurements into a limited number of composite graded traits (latent pure types) in a sample of 61 nuclear families comprising 80 subjects with ICD-10/DSM-IV schizophrenia or schizophrenia spectrum disorders and 138 nonpsychotic first-degree relatives. GoM probability scores, computed for all subjects, allowed individuals to be partly assigned to more than one pure type. Two distinct and contrasting neurocognitive phenotypes, one familial, associated with paranoid schizophrenia, and one sporadic, associated with nonparanoid schizophrenia, accounted for 74% of the affected subjects. Combining clinical diagnosis with GoM scores to stratify the entire sample into liability classes, and using variance component analysis (SOLAR), in addition to parametric and nonparametric multipoint linkage analysis, we explored candidate regions on chromosomes 6, 10 and 22. The results indicated suggestive linkage for the familial neurocognitive phenotype (multipoint MLS 2.6 under a low-penetrance model and MLS>3.0 under a high-penetrance model) to a 14 cM area on chromosome 6, including the entire HLA region. Results for chromosomes 10 and 22 were negative. The findings suggest that the familial neurocognitive phenotype may be a pleiotropic expression of genes underlying the susceptibility to paranoid schizophrenia. We conclude that use of composite neurocognitive and personality trait measurements as correlated phenotypes supplementing clinical diagnosis can help stratify the liability to schizophrenia across all members of families prior to linkage, allow the search for susceptibility genes to focus selectively on subsets of families at high genetic risk, and augment considerably the power of genetic analysis.

Acts of control in schizophrenia: dissociating the components of inhibition

BACKGROUND

Inhibitory deficits have been frequently reported in schizophrenia. Such deficits are usually associated with activities of prefrontal cortex and related networks. An understanding of intentional inhibitory control requires knowledge of how actions are planned and initiated and the components involved in stopping these actions.

METHODS

Patients with schizophrenia, a psychosis comparison group and a healthy control group participated in a visual choice reaction time (go) task and attempted to inhibit their responses to the go task when an auditory 'stop' signal was heard.

RESULTS

Schizophrenia patients demonstrated significantly slower response execution but the estimated speed of inhibition was not significantly different from that of healthy controls. Both patient groups were impaired in their ability to inhibit a response across a range of stop-signal delays. The poorer performance of schizophrenia patients only was related to a difficulty in reliably triggering the inhibitory response.

CONCLUSIONS

Impaired response inhibition is not unique to schizophrenia. However, the nature of their problem is markedly different from that of other psychopathological groups. Possible neural mechanisms underpinning difficulties in triggering inhibitory responses and in the voluntary initiation of actions in schizophrenia are considered.