Search

Nattokinase, the fibrinolytic serine protease, has been shown to be beneficial in preventing strokes caused due to blood clots. Therefore, synthesis of recombinant nattokinase in a host system, which can be both safe for human consumption as well as demonstrate good productivity and amenable to the downstream processing, will have a great socioeconomic significance. A nat05 gene encoding nattokinase – the most important serine protease secreted by the Bacillus subtilis natto – was cloned from B. subtilis strain N05 and expressed using pHT43 plasmid in another B. subtilis strain (BD170). Enzymatic assays, as well as sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and zymogram, were employed to assess the efficiency of the production of nattokinase using a relatively novel recombinant DNA technique. Among the five recombinant bacterial clones (R1–R5), R4 was found to secrete high amounts of nattokinase into the culture medium, as evidenced by the total proteolytic enzyme assay, fibrinolytic enzyme assay, SDS-PAGE, and zymogram. A preliminary analysis of the biochemical properties of the crude enzyme showed characteristics that are typical of nattokinase as reported by other studies. Thus, in this study, we were able to successfully produce nattokinase in B. subtilis strain (BD170) using recombinant DNA approach. The R4 recombinant clone that was found to secrete nattokinase can be used as a source of recombinant protein that can be further purified for various therapeutic applications, or the strain could be used as a probiotic bacterium in functional foods.

Background: While deep brain stimulation has been successful in treating movement disorders, such as in Parkinson's disease, its potential application in alleviating memory disorders is inconclusive., Objective/hypothesis: We investigated the role of the location of the stimulating electrode on memory improvement and hypothesized that entorhinal white versus gray matter stimulation would have differential effects on memory., Methods: Intracranial electrical stimulation was applied to the entorhinal area of twenty-two participants with already implanted electrodes as they completed visual memory tasks., Results: We found that stimulation of right entorhinal white matter during learning had a beneficial effect on subsequent memory, while stimulation of adjacent gray matter or left-sided stimulation was ineffective. This finding was consistent across three different visually guided memory tasks., Conclusions: Our results highlight the importance of precise stimulation site on modulation of human hippocampal-dependent memory and suggest that stimulation of afferent input into the right hippocampus may be an especially promising target for enhancement of visual memory., Competing Interests: Declaration of competing interest None., (Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.)

The theta rhythm-a slow (6-12 Hz) oscillatory component of the local field potential-plays a critical role in spatial navigation and memory by coordinating the activity of neuronal ensembles within the medial temporal lobe (MTL). Although theta has been extensively studied in freely moving rodents, its presence in humans has been elusive and primarily investigated in stationary subjects. Here we used a unique clinical opportunity to examine theta within the human MTL during untethered, real-world ambulatory movement. We recorded intracranial electroencephalographic activity from participants chronically implanted with the wireless NeuroPace responsive neurostimulator (RNS) and tracked their motion with sub-millimeter precision. Our data revealed that movement-related theta oscillations indeed exist in humans, such that theta power is significantly higher during movement than immobility. Unlike in rodents, however, theta occurs in short bouts, with average durations of ∼400 ms, which are more prevalent during fast versus slow movements. In a rare opportunity to study a congenitally blind participant, we found that both the prevalence and duration of theta bouts were increased relative to the sighted participants. These results provide critical support for conserved neurobiological characteristics of theta oscillations during ambulatory spatial navigation, while highlighting some fundamental differences across species in these oscillations between humans and rodents., (Published by Elsevier Ltd.)

The hippocampus is critical for episodic memory, and synaptic changes induced by long-term potentiation (LTP) are thought to underlie memory formation. In rodents, hippocampal LTP may be induced through electrical stimulation of the perforant path. To test whether similar techniques could improve episodic memory in humans, we implemented a microstimulation technique that allowed delivery of low-current electrical stimulation via 100 μm -diameter microelectrodes. As thirteen neurosurgical patients performed a person recognition task, microstimulation was applied in a theta-burst pattern, shown to optimally induce LTP. Microstimulation in the right entorhinal area during learning significantly improved subsequent memory specificity for novel portraits; participants were able both to recognize previously-viewed photos and reject similar lures. These results suggest that microstimulation with physiologic level currents-a radical departure from commonly used deep brain stimulation protocols-is sufficient to modulate human behavior and provides an avenue for refined interrogation of the circuits involved in human memory.