Catalytic RNA nano-objects formed by self-assembly of group I ribozyme dimers serving as unit structures.

Ribozymes with modular structures are attractive platforms for the construction of nanoscale RNA objects with biological functions. We designed group I ribozyme dimers as unit ribozyme dimers (Urds), which self-assembled to form their polymeric states and also oligomeric states with defined numbers of Urds. Assembly of Urds yielded catalytic ability of a pair of distinct ribozyme units to cleave two distinct substrates. The morphologies of the assembled ribozyme structures were observed directly by atomic force microscopy (AFM).

Timely manner application of hand orthoses to patients with amyotrophic lateral sclerosis: A case report.

BACKGROUND: In patients with amyotrophic lateral sclerosis, the atrophy of hand muscles often causes impairment of thumb/finger motion and disabilities in their activities of daily living. Hand orthoses are effective for such impairment and disabilities; however, there are some difficulties in their application. CASE DESCRIPTION AND METHODS: In this case report, we present the timely application of hand orthoses and introduce our clinical algorithm for the application of hand orthoses to patients with amyotrophic lateral sclerosis. FINDINGS AND OUTCOMES: Our clinical algorithm was applied to 11 patients. The numbers of applications and the durations of the use of orthoses were as follows: 4, web spacer; 4, short thumb spica; 8, long thumb spica; and 2, cock-up splint; and 2.75, 2.0, 0.63, and 2.0 months, respectively. CONCLUSIONS: The clinical algorithm for the application of hand orthoses is helpful in choosing the optimal orthoses and contributes to maximizing patients' function, independence, and quality of life. CLINICAL RELEVANCE: Hand orthoses are useful for improving the activities of daily living of patients with amyotrophic lateral sclerosis. The clinical algorithm might be helpful for many physicians in choosing the optimal orthoses in a timely manner.

Functional stability of unliganded envelope glycoprotein spikes among isolates of human immunodeficiency virus type 1 (HIV-1).

The HIV-1 envelope glycoprotein (Env) spike is challenging to study at the molecular level, due in part to its genetic variability, structural heterogeneity and lability. However, the extent of lability in Env function, particularly for primary isolates across clades, has not been explored. Here, we probe stability of function for variant Envs of a range of isolates from chronic and acute infection, and from clades A, B and C, all on a constant virus backbone. Stability is elucidated in terms of the sensitivity of isolate infectivity to destabilizing conditions. A heat-gradient assay was used to determine T(90) values, the temperature at which HIV-1 infectivity is decreased by 90% in 1 h, which ranged between ∼40 to 49°C (n = 34). For select Envs (n = 10), the half-lives of infectivity decay at 37°C were also determined and these correlated significantly with the T(90) (p = 0.029), though two 'outliers' were identified. Specificity in functional Env stability was also evident. For example, Env variant HIV-1(ADA) was found to be labile to heat, 37°C decay, and guanidinium hydrochloride but not to urea or extremes of pH, when compared to its thermostable counterpart, HIV-1(JR-CSF). Blue native PAGE analyses revealed that Env-dependent viral inactivation preceded complete dissociation of Env trimers. The viral membrane and membrane-proximal external region (MPER) of gp41 were also shown to be important for maintaining trimer stability at physiological temperature. Overall, our results indicate that primary HIV-1 Envs can have diverse sensitivities to functional inactivation in vitro, including at physiological temperature, and suggest that parameters of functional Env stability may be helpful in the study and optimization of native Env mimetics and vaccines.

Identifying key components of the PrPC-PrPSc replicative interface.

In prion disease, direct interaction between the cellular prion protein (PrP(C)) and its misfolded disease-associated conformer PrP(Sc) is a crucial, although poorly understood step promoting the formation of nascent PrP(Sc) and prion infectivity. Recently, we hypothesized that three regions of PrP (corresponding to amino acid residues 23-33, 98-110, and 136-158) interacting specifically and robustly with PrP(Sc), likely represent peptidic components of one flank of the prion replicative interface. In this study, we created epitope-tagged mouse PrP(C) molecules in which the PrP sequences 23-33, 98-110, and 136-158 were modified. These novel PrP molecules were individually expressed in the prion-infected neuroblastoma cell line (ScN2a) and the conversion of each mutated mouse PrP(C) substrate to PrP(Sc) compared with that of the epitope-tagged wild-type mouse PrP(C). Mutations within PrP 98-110, substituting all 4 wild-type lysine residues with alanine residues, prevented conversion to PrP(Sc). Furthermore, when residues within PrP 136-140 were collectively scrambled, changed to alanines, or amino acids at positions 136, 137, and 139 individually replaced by alanine, conversion to PrP(Sc) was similarly halted. However, other PrP molecules containing mutations within regions 23-33 and 101-104 were able to readily convert to PrP(Sc). These results suggest that PrP sequence comprising residues 98-110 and 136-140 not only participates in the specific binding interaction between PrP(C) and PrP(Sc), but also in the process leading to conversion of PrP(Sc)-sequestered PrP(C) into its disease-associated form.

Transport and toxic mechanism for aluminum citrate in human neuroblastoma SH-SY5Y cells.

Aluminum (Al) is thought to be a risk factor for neurodegenerative disorders, but the molecular mechanism has been not clarified yet. In this study, we examined how a transport system handled transport of Al citrate, the major Al species in brain, and effect of Al citrate treatment on expression of the transporter and on susceptibility to oxidative stress in human neuroblastoma SH-SY5Y cells. Uptake of Al citrate by the cells was temperature- and concentration-dependent, and inwardly-directed Na(+)-gradient-independent. Simultaneous application and preloading of L-cystine or L-glutamate inhibited and stimulated, respectively, the Al citrate uptake by SH-SY5Y cells, demonstrating kinetically that Na(+)-independent L-cystine/L-glutamate exchanger, system Xc(-), is involved in its uptake. When the cells were treated with Al citrate, but not citrate, for 2 weeks, but not a day, the expression of the transporter was decreased. Although the cell viability and glutathione content of the cells were not altered by the treatment with Al citrate alone, the number of dead cells among the Al citrate-treated cells increased on exposure to oxidative stress caused by a glucose deprivation/reperfusion treatment. These findings demonstrate that Al citrate is a substrate for system Xc(-), and that chronic treatment with Al citrate causes downregulation of the transporter and increases the vulnerability of the cells to oxidative stress without a direct effect on the viability or GSH content.

Anaerobic degradation of aromatic compounds by magnetospirillum strains: isolation and degradation genes.

Four Magnetospirillum strains degrading toluene, phenol, benzoate, and other aromatic compounds under anaerobic conditions were isolated from denitrifying enrichment cultures. One of the isolates, toluene-degrading strain TS-6, contained genes that are homologous to those encoding benzylsuccinate synthase (Bss) and benzoyl-CoA reductase (Bcr), two key enzymes of anaerobic toluene and benzoate degradation respectively in known denitrifying bacteria. Transcription of the genes was confirmed. It was controlled by growth substrates and oxygen conditions, but bcr genes were unexpectedly expressed in aerobic cells grown on benzoate. It was confirmed that the genus Magnetospirillum represents the third genus of denitrifying bacteria capable of degrading aromatic compounds under anaerobic conditions, besides the genera Thauera and Azoarcus.