The nonabelian Liouville-Arnold integrability by quadratures problem: a symplectic approach

A symplectic theory approach is devised for solving the problem of algebraic-analytical construction of integral submanifold imbeddings for integrable (via the nonabelian Liouville-Arnold theorem) Hamiltonian systems on canonically symplectic phase spaces

Media on-demand: continuous reconstitution of a chemically defined media directly from solids

Chemically defined media are reconstituted batchwise and stored in hold tanks until use. To avoid large hold tanks and batchwise production of media, we developed continuous on-demand reconstitutions directly from solids consisting of a hopper and a screw conveyor capable of feeding dry powdered media with the required precision +/- 5% at low dosing rates of 0.171 g min(-1). A commercially available dry powdered cell culture medium was continuously fed over a duration of 12 h into a mixer which was connected to a UV-cell for monitoring and the media were compared to a batchwise production. A comparable amino acid, carbohydrate, and osmolality profile to a batchwise reconstitution could be obtained. Cell cultivation showed comparable performance of batch and continuous reconstitution for two CHO cell lines producing the antibodies adalimumab and trastuzumab on a small and benchtop scale. In-depth analysis of the produced antibodies showed the same glycosylation pattern, other posttranslational profiles such as methionine oxidation and deamidation compared to batchwise reconstitution. Therefore, we conclude a continuous reconstitution of the medium results in the same quality of the product. A continuous on-demand media reconstitution will impact the supply chain and significantly reduce the floor space necessary for preparation and storage.Proteomic

Microstimulation of human somatosensory cortex evokes task-dependent, spatially patterned responses in motor cortex

The primary motor (M1) and somatosensory (S1) cortices play critical roles in motor control but the signaling between these structures is poorly understood. To fill this gap, we recorded – in three participants in an ongoing human clinical trial (NCT01894802) for people with paralyzed hands – the responses evoked in the hand and arm representations of M1 during intracortical microstimulation (ICMS) in the hand representation of S1. We found that ICMS of S1 activated some M1 neurons at short, fixed latencies consistent with monosynaptic activation. Additionally, most of the ICMS-evoked responses in M1 were more variable in time, suggesting indirect effects of stimulation. The spatial pattern of M1 activation varied systematically: S1 electrodes that elicited percepts in a finger preferentially activated M1 neurons excited during that finger’s movement. Moreover, the indirect effects of S1 ICMS on M1 were context dependent, such that the magnitude and even sign relative to baseline varied across tasks. We tested the implications of these effects for brain-control of a virtual hand, in which ICMS conveyed tactile feedback. While ICMS-evoked activation of M1 disrupted decoder performance, this disruption was minimized using biomimetic stimulation, which emphasizes contact transients at the onset and offset of grasp, and reduces sustained stimulation

FRET-based mapping of calmodulin bound to the RyR1 Ca2+ release channel

Calmodulin (CaM) functions as a regulatory subunit of ryanodine receptor (RyR) channels, modulating channel activity in response to changing [Ca2+]i. To investigate the structural basis of CaM regulation of the RyR1 isoform, we used site-directed labeling of channel regulatory subunits and fluorescence resonance energy transfer (FRET). Donor fluorophore was targeted to the RyR1 cytoplasmic assembly by preincubating sarcoplasmic reticulum membranes with a fluorescent FK506-binding protein (FKBP), and FRET was determined following incubations in the presence of fluorescent CaMs in which acceptor fluorophore was attached within the N lobe, central linker, or C lobe. Results demonstrated strong FRET to acceptors attached within CaM's N lobe, whereas substantially weaker FRET was observed when acceptor was attached within CaM's central linker or C lobe. Surprisingly, Ca2+ evoked little change in FRET to any of the 3 CaM domains. Donor–acceptor distances derived from our FRET measurements provide insights into CaM's location and orientation within the RyR1 3D architecture and the conformational switching that underlies CaM regulation of the channel. These results establish a powerful new approach to resolving the structure and function of RyR channels