It can travel through bodily fluids, targeting and inactivating enzymes responsible for cell-wall synthesis in gram-positive bacteria, meanwhile avoiding the surrounding non-targets. Penicillin can protect itself from spontaneous hydrolysis in the body in its anionic form while storing its potential as a strong acylating agent, activated only upon approach to the target transpeptidase enzyme and protonated in the active centre. This targeted protonation neutralizes the carboxylic acid moiety, which is weakening of the β-lactam ring N–C(=O) bond, resulting in a self-activation. Specific structural requirements are equated to constructing the perfect mousetrap for catching targeted prey.Penicillin kills bacteria by inhibiting the completion of the synthesis of peptidoglycans, the structural component of bacterial cell wall. It specifically inhibits the activity of enzymes that are needed for the cross-linking of peptidoglycans during the final step in cell wall biosynthesis. It does this by binding to penicillin binding proteins with the β-lactam ring, a structure found on penicillin molecules. This causes the cell wall to weaken due to fewer cross-links and means water uncontrollably flows into the cell because it cannot maintain the correct osmotic gradient. This results in cell lysis and death. Bacteria constantly remodel their peptidoglycan cell walls, simultaneously building and breaking down portions of the cell wall as they grow and divide. During the last stages of peptidoglycan biosynthesis, uridine diphosphate-N-acetylmuramic acid pentapeptide (UDP-MurNAc) is formed in which the fourth and fifth amino acids are both D-alanyl-D-alanine. The transfer of D-alanine is done (catalysed) by the enzyme DD-transpeptidase (penicillin-binding proteins are such type).
More research needs to be conducted in order to establish the lasting benefit of constraint-induced movement therapy. Brain computer interface (BCI) systems have been proposed as a tool for rehabilitation of monoplegia, specifically in the upper limb after a stroke. BCI systems provide sensory feedback in the brain via functional electrical stimulation, virtual reality environments, or robotic systems, which allows for the use of brain signals. This is extremely crucial because the networking in the brain is often compromised after a stroke, leading to impaired movement or paralysis. BCI systems allow for detection of intention to move through the primary motor cortex, then provide the matched sensory stimulation according to feedback that is provided. This leads to activity-dependent plasticity within the user, requiring them to pay careful attention to tasks that require the activation or deactivation of specific brain areas. BCI systems utilize different sources of information for feedback, including electroencephalography (EEG), magnetoencephalography, functional magnetic resonance imaging, near-infrared spectroscopy, or electrocorticography. Among all of these, the EEG signals are the most useful for this type of rehabilitation because they are highly accurate and stable.Another form of treatment for monoplegia is functional electrical stimulation (FES). It is targeted at patients who acquired monoplegia through incidents such as a spinal cord injury, stroke, multiple sclerosis, or cerebral palsy and utilizes electrical stimulation in order to cause the remaining motor units in the paralyzed muscles to contract. As in traditional muscular training, FES improves the force with which the unaffected muscles contract.