Acetylcholine precursor, citicoline (cytidine 5'-diphosphocholine), reduces hypoglycaemia-induced neuronal death in rats

Citicoline (cytidine 5'-diphosphocholine) is an important precursor for the synthesis of neuronal plasma membrane phospholipids, mainly phosphatidylcholine. The administration of citicoline serves as a choline donor for the synthesis of acetylcholine. Citicoline has been shown to reduce the neuronal injury in animal models with cerebral ischaemia and in clinical trials of stroke patients. Citicoline is currently being investigated in a multicentre clinical trial. However, citicoline has not yet been examined the context of hypoglycaemia-induced neuronal death. To clarify the therapeutic impact of citicoline in hypoglycaemia-induced neuronal death, we used a rat model with insulin-induced hypoglycaemia. Acute hypoglycaemia was induced by i.p. injection of regular insulin (10 U kg^-1 ) after overnight fasting, after which iso-electricity was maintained for 30 minutes. Citicoline injections (500 mg/kg, i.p.) were started immediately after glucose reperfusion. We found that post-treatment of citicoline resulted in significantly reduced neuronal death, oxidative injury and microglial activation in the hippocampus compared to vehicle-treated control groups at 7 days after induced hypoglycaemia. Citicoline administration after hypoglycaemia decreased immunoglobulin leakage via blood-brain barrier disruption in the hippocampus compared to the vehicle group. Citicoline increased choline acetyltransferase expression for phosphatidylcholine synthesis after hypoglycaemia. Altogether, the present findings suggest that neuronal membrane stabilisation by citicoline administration can save neurones from the degeneration process after hypoglycaemia, as seen in several studies of ischaemia. Therefore, the results suggest that citicoline may have therapeutic potential to reduce hypoglycaemia-induced neuronal death.

3D reconstruction based on compressed-sensing (CS)-based framework by using a dental panoramic detector

In this work, we propose a practical method that can combine the two functionalities of dental panoramic and cone-beam CT (CBCT) features in one by using a single panoramic detector. We implemented a CS-based reconstruction algorithm for the proposed method and performed a systematic simulation to demonstrate its viability for 3D dental X-ray imaging. We successfully reconstructed volumetric images of considerably high accuracy by using a panoramic detector having an active area of 198.4 mm × 6.4 mm and evaluated the reconstruction quality as a function of the pitch (p) and the angle step (Δθ). Our simulation results indicate that the CS-based reconstruction almost completely recovered the phantom structures, as in CBCT, for p≤2.0 and θ≤6°, indicating that it seems very promising for accurate image reconstruction even for large-pitch and few-view data. We expect the proposed method to be applicable to developing a cost-effective, volumetric dental X-ray imaging system.

Anterior spinal artery syndrome following total hip arthroplasty under epidural anaesthesia

We present a case of anterior spinal artery syndrome in a 57-year-old man having a total hip arthroplasty under epidural anaesthesia. Epidural insertion and surgery were uneventful. Postoperatively bilateral lower limb motor weakness was attributed to the initial dose of local anaesthetic. There was no change in neurological status 24 hours later. Magnetic resonance imaging demonstrated spinal cord infarction. The diagnosis of anterior spinal artery syndrome was made based on the patient's neurological condition and MRI findings.

TNFalpha-308A allele in juvenile dermatomyositis: association with increased production of tumor necrosis factor alpha, disease duration, and pathologic calcifications

OBJECTIVE

To characterize the association between the TNFalpha-308A allele and 1) duration of active disease, 2) peripheral blood mononuclear cell (PBMC) synthesis of tumor necrosis factor alpha (TNFalpha) in vitro, and 3) pathologic calcifications in patients with juvenile dermatomyositis (DM).

METHODS

The TNFalpha-308 alleles were determined by polymerase chain reaction in 37 white patients with juvenile DM and in 29 control subjects. Patients were grouped according to duration of immunosuppressive therapy: long (> or =36 months) or short (<36 months). Unstimulated PBMC were examined by enzyme-linked immunosorbent assay for TNFalpha production in vitro. Sixty-five white patients with juvenile DM were examined for pathologic calcifications.

RESULTS

TNFalpha-308A was identified in 18 of 37 patients with juvenile DM, in contrast with 5 of 29 controls (P = 0.009). Sixteen of the 18 patients with juvenile DM who had the TNFalpha-308A allele had a disease course > or =36 months, compared with 6 of 19 patients with TNFalpha-308G (P = 0.001). PBMC from 16 of the 18 juvenile DM patients with TNFalpha-308A synthesized more TNFalpha (median 53 pg/ml) compared with PBMC from 9 of 19 patients with TNFalpha-308G (median 19 pg/ml) (P = 0.007). Nineteen of 22 juvenile DM patients requiring therapy for > or =36 months produced more TNFalpha (median 20.5 pg/ml) in comparison with 6 of 15 juvenile DM patients with a <36-month treatment course (median TNFalpha 0.0 pg/ml) (P = 0.005). Detectable calcifications were present in 3 of 8 children with juvenile DM who had TNFalpha-308AA, compared with 2 of 21 children with TNFalpha-308AG and 1 of 36 children who had TNFalpha-308GG (P = 0.017).

CONCLUSION

A long course of juvenile DM and the presence of pathologic calcifications were associated with the TNFalpha-308A allele and with the increased production of TNFalpha, which may perpetuate the inflammatory response.

Blockade of T cell activation using a surface-linked single-chain antibody to CTLA-4 (CD152)

CTLA-4 (CD152) engagement can down-regulate T cell activation and promote the induction of immune tolerance. However, the strategy of attenuating T cell activation by engaging CTLA-4 has been limited by sharing of its natural ligands with the costimulatory protein CD28. In the present study, a CTLA-4-specific single-chain Ab (scFv) was developed and expressed on the cell surface to promote selective engagement of this regulatory molecule. Transfectants expressing anti-CTLA-4 scFv at their surface bound soluble CTLA-4 but not soluble CD28. Coexpression of anti-CTLA-4 scFv with anti-CD3epsilon and anti-CD28 scFvs on artificial APCs reduced the proliferation and IL-2 production by resting and preactivated bulk T cells as well as CD4+ and CD8+ T cell subsets. Importantly, expression of anti-CTLA-4 scFv on the same cell surface as the TCR ligand was essential for the inhibitory effects of CTLA-4-specific ligation. CTLA-4-mediated inhibition of tyrosine phosphorylation of components of the proximal TCR signaling apparatus was similarly dependent on coexpression of TCR and CTLA-4 ligands on the same surface. These findings support a predominant role for CTLA-4 function in the modification of the proximal TCR signal. Using T cells from DO11.10 and 2C TCR transgenic mice, negative regulatory effects of selective CTLA-4 ligation were also demonstrated during the stimulation of Ag-specific CD4+ and CD8+ T cells by MHC/peptide complexes. Together these studies demonstrate that selective ligation of CTLA-4 using a membrane-bound scFv results in attenuated T cell responses only when coengaged with the TCR during T cell/APC interaction and define an approach to harnessing the immunomodulatory potential of CTLA-4-specific ligation.

Molecular basis of T cell inactivation by CTLA-4

CTLA-4, a negative regulator of T cell function, was found to associate with the T cell receptor (TCR) complex zeta chain in primary T cells. The association of TCRzeta with CTLA-4, reconstituted in 293 transfectants, was enhanced by p56(lck)-induced tyrosine phosphorylation. Coexpression of the CTLA-4-associated tyrosine phosphatase, SHP-2, resulted in dephosphorylation of TCRzeta bound to CTLA-4 and abolished the p56(lck)-inducible TCRzeta-CTLA-4 interaction. Thus, CTLA-4 inhibits TCR signal transduction by binding to TCRzeta and inhibiting tyrosine phosphorylation after T cell activation. These findings have broad implications for the negative regulation of T cell function and T cell tolerance.