Drug Binding to α1-Acid Glycoprotein Studied by Circular Dichroism

The interactions of acidic and basic drugs with ₁-acid glycoprotein (₁-AGP) were investigated using circular dichroism (CD) measurements. Extrinsic Cotton effects were generated by the binding of drugs to ₁-AGP. The CD data suggested the presence of a single binding site on the ₁-AGP molecule. The induced ellipticities of the acidic drug–₁-AGP system decreased with increasing pH, while the ellipticities for the basic drugs increased with pH. The ellipticities for all drugs were reduced by the addition of fatty acids. Furthermore, the induced ellipticities decreased in the presence of cesium chloride for basic drugs bound to ₁-AGP. The extrinsic Cotton effects therefore appear to result from hydrophobic interaction with ₁-AGP for the acidic drugs and from hydrophobic and electrostatic interactions for the basic drugs.     

Directed differentiation of telencephalic precursors from embryonic stem cells

We demonstrate directed differentiation of telencephalic precursors from mouse embryonic stem (ES) cells using optimized serum-free suspension culture (SFEB culture). Treatment with Wnt and Nodal antagonists (Dkk1 and LeftyA) during the first 5 d of SFEB culture causes nearly selective neural differentiation in ES cells ( approximately 90%). In the presence of Dkk1, with or without LeftyA, SFEB induces efficient generation ( approximately 35%) of cells expressing telencephalic marker Bf1. Wnt3a treatment during the late culture period increases the pallial telencephalic population (Pax6(+) cells yield up to 75% of Bf1(+) cells), whereas Shh promotes basal telencephalic differentiation (into Nkx2.1(+) and/or Islet1/2(+) cells) at the cost of pallial telencephalic differentiation. Thus, in the absence of caudalizing signals, floating aggregates of ES cells generate naive telencephalic precursors that acquire subregional identities by responding to extracellular patterning signals.     

Photoreactive nanotool for cell aggregation and immobilization

We developed a new method to prepare aggregates of specific cells and immobilize cells on a substrate with specific shapes by using a synthetic multifunctional tool, which consisted of a cell adhesive Arg-Gly-Asp (RGD) sequence, a photoreactive phenyl azido group and a biotin group. This chemical nanotool, RGD-2-(6-[biotinamido]-2-(p-azidobenzamido)-hexaneamido)ethyl-1,3′-dithio-proprionate (RGD-BED) was added to human umbilical vein endothelial cells to bind to receptors via the ligand–receptor interaction. Next a photoimmobilization of the binding RGD-BED was carried out by UV irradiation to covalently couple a phenyl azido moiety of RGD-BED with the neighboring site of the integrin receptor. We found that not only the migration distance of RGD-BED immobilized cells was diminished, but also the cell morphology was fixed on the substrate due to the blocking of integrin receptors by RGD-BED. In contrast, the addition of biocytin-containing polymers, poly(N-methacryloyloxy biocytin-co-dimethylacrylamide), and avidin to the RGD-BED-immobilized cells led to restore cellular migration behavior, probably arising from the increase in the rigidity of the environment surrounding the cells. Furthermore, by the addition of avidin to the RGD-BED-immobilized cells, three-dimensional cell aggregates were formed due to the cross-linking of the biotin moieties of RGD-BED. These results show that RGD-BED is a potential nanotool not only to label and collect targeted cells by the formation of cell aggregates but also to suppress mobility and morphologies of specific cells to be applicable for medical treatments.     

Tranilast inhibits the proliferation of uterine leiomyoma cells in vitro through G1 arrest associated with the induction of p21(waf1) and p53

Uterine leiomyoma is a mesenchymal tumor composed of smooth muscle cells with fibrous tissues and many mast cells. Tranilast is known to suppress fibrosis or to work as a mast cell stabilizer and is reported to inhibit proliferation of vascular smooth muscle cells. In this study, we examined the effects of tranilast on cultured human leiomyoma cells in vitro to evaluate whether this agent has the potential to inhibit the growth of uterine leiomyomas. Tranilast inhibited the proliferation of cultured leiomyoma cells in a dose-dependent manner without any cytotoxic effect or induction of apoptosis. In association with the inhibitory effect, tranilast induced the cyclin-dependent kinase (CDK) inhibitor p21(waf1) and tumor suppressor gene p53 and decreased CDK2 activity. These results suggest that tranilast arrests the proliferation of uterine leiomyoma cells at the G0/G1 phase, through the suppression of CDK2 activity via an induction of p21(waf1) and p53. Tranilast was concluded to be a potent agent to inhibit proliferative activity of uterine leiomyoma cells.     

Drastically Progressive Ethambutol-induced Optic Neuropathy after Withdrawal of Ethambutol: A Case Report and Literature Review

Ethambutol-induced optic neuropathy (EON) is a well-known complication, although low-dose ethambutol seldom causes EON. An 85-year-old man with non-tuberculous mycobacterial lung disease was taking antibiotics, including low-dose ethambutol. On day 85 of treatment, the diagnosis of EON was made. Despite prior discontinuation, his best corrected visual acuity drastically deteriorated from 20/17 (right eye) and 20/20 (left eye) to 20/330 (right eye) and 20/1,000 (left eye) within 3 weeks, and this symptom did not resolve. To our knowledge, there have been no reported cases with drastically progressing and irreversible EON even after the withdrawal of low-dose and short-term ethambutol.