Type I toxin-antitoxin loci consist of two genes: a small, hydrophobic, potentially toxic protein, and a small RNA (sRNA) antitoxin. The sRNA represses toxin gene expression by base pairing to the ...toxin mRNA. A previous bioinformatics search predicted a duplicated type I locus within Escherichia coli O157:H7 (EHEC), which we have named the gene pairs zorO-orzO and zorP-orzP. We show that overproduction of the zorO gene is toxic to E. coli; co-expression of the sRNA OrzO can neutralize this toxicity, confirming that the zorO-orzO pair is a true type I toxin-antitoxin locus. However, OrzO is unable to repress zorO in a strain deleted for RNase III, indicating that repression requires cleavage of the target mRNA. Sequence analysis and mutagenesis studies have elucidated a nucleotide sequence region (V1) that allows differential recognition of the zorO mRNA by OrzO and not OrzP, and a specific single nucleotide within the V1 of OrzO that is critical for repression of zorO. Although there are 18 nt of complementarity between the OrzO sRNA and the zorO mRNA, not all base pairing interactions are needed for repression; however, the amount needed is dependent on whether there is continuous or discontinuous complementarity to the target mRNA.
Abstract
INTRODUCTION:
Previously, the authors presented the coaptation of C3 and C4 primary rami to one of brachial plexus trunks to regain function from cervical root avulsion-caused paralysis. The ...purpose of this presentation is 2-fold: (1) discuss specific surgical techniques and (2) discuss control or prevention of intractable pain associated with root avulsion.
METHODS:
(1) The surgical procedure consists of exposure of C3 and C4 anterior rami coaptation to the upper trunk (Erb-Duchenne) or lower trunk (Klumpke), with sural nerve bridge graft, and additionally intercostal nerve coaptation to median and ulnar nerves for flail arm. (2) Of 30 total patients, 23 patients presented with Erb-Duchenne palsy due to C5 and C6 root avulsion, 3 presented with Klumpke palsy due to C8 and T1 avulsion, and 4 presented with C5 through T1 avulsion (a flail arm). These patients are divided into 2 groups according to pain control: Group 1 patients were operated on within 3 months after avulsion, group 2 was treated surgically later than 3 months postinjury.
RESULTS:
(1) The surgical procedure consists of exposure of C3 and C4 anterior rami coaptation to the upper trunk (Erb-Duchenne) or lower trunk (Klumpke), with sural nerve bridge graft, and additionally intercostal nerve coaptation to median and ulnar nerves for flail arm. (2) Of 30 patients, 23 patients presented with Erb-Duchenne palsy due to C5 and C6 root avulsion, 3 presented with Klumpke palsy due to C8 and T1 avulsion, and 4 presented with C5 through T1 avulsion (a flail arm). These patients are divided into 2 groups according to pain control: Group 1 patients were operated on within 3 months after avulsion; group 2 was treated surgically later than 3 months post injury.
CONCLUSION:
Coaptation procedures are effective to control arm and hand pain associated with nerve root avulsion.
The tethered cord syndrome (TCS) is a stretch-induced functional disorder of the spinal cord with its caudal part anchored by an inelastic structure.
This article clarifies the reversible lesions ...that occur in the cord segments above any of the inelastic abnormalities. These lesions are found mostly in the lumbosacral cord, occasionally in the cervical cord and closely correlate with clinical findings. Imaging studies alone do not allow accurate diagnosis of the TCS. The authors emphasize the importance of adhering to the physiological terms "tethered cord syndrome" and "tethered spinal cord" to avoid controversies derived from terms that are not based on the pathophysiology of TCS.
Tethered cord syndrome (TCS) is a stretch-induced functional disorder of the spinal cord. The mechanical cause of TCS is an inelastic structure anchoring the caudal end of the spinal cord that ...prevents cephalad movement of the lumbosacral cord. Stretching of the spinal cord occurs in patients either when the spinal column grows faster than the spinal cord or when the spinal cord undergoes forcible flexion and extension. Research in patients and experimental animals suggests that there is a link between the clinical dysfunctions that characterize TCS and putative pathophysiological changes that accompany this syndrome. Among these changes are depression of electrophysiological activity and shifts in the reduction/oxidation ratio of cytochrome oxidase. The latter suggests that there is impairment of oxidative metabolism. These putative pathophysiological changes in TCS occur mainly within the lumbosacral cord under excessive tension. The authors discuss the pathophysiology of TCS and examine related symptoms.
An improved, laser-induced fluorescence-based micro-optical biosensor was designed and fabricated, with cyclic olefin copolymer (COC) optical waveguides, a poly(methyl methacrylate) (PMMA) fluidic ...substrate with an array of microlenses, and a COC coupling prism integrated with the waveguide substrate or cover plate. The double-sided hot embossed fluidic substrate had sampling zone microchannels on the bottom and microlenses on the top. Dissolved COC injected into polydimethylsiloxane (PDMS) lost molds embedded the waveguides in the PMMA cover plate and formed the integrated coupling prism. The embedded COC waveguide was flycut down to <inline-formula> <tex-math notation="LaTeX">50~\mu \text{m} </tex-math></inline-formula>. The cover plate and shallow, 1:20 aspect ratio, microchannels were thermal fusion bonded using a pressure-assisted boiling point control system, without sagging. The large COC prism coupled better to the waveguide. The highest intensity evanescent excitation of the waveguide was obtained near the critical angle. The maximum signal-to-noise ratio (SNR) was 119 and the lowest detection limit was 7.34 <inline-formula> <tex-math notation="LaTeX">\times 10^{\mathbf {-20}} </tex-math></inline-formula> mol at a SNR of 2 for a <inline-formula> <tex-math notation="LaTeX">100~\mu \text{m} </tex-math></inline-formula> wide by <inline-formula> <tex-math notation="LaTeX">50~\mu \text{m} </tex-math></inline-formula> deep waveguide. The microlenses highly focused the fluorescent radiation in the sampling zone. The microfabricated waveguide enables rapid, low-cost detection of fluorescent samples with high SNR, a low detection limit, and high sampling efficiency. 2020-0067
✓Tethered cord syndrome (TCS) is a stretch-induced functional disorder of the spinal cord due to the fact that its caudal portion is anchored by an inelastic structure. The functional lesion of TCS ...is generally situated in the lumbosacral cord, and many authors have shown that the syndrome is reversible via surgery to untether the cord. To clarify the expressions relevant to TCS, such as “cord tethering” and “tethered cord,” the authors have formulated three categories. These categories include cases that show the anatomical appearance of spinal cord stretching. Among them, Category 1 is isolated to represent the “true TCS.” The authors focus their discussion of the pathophysiology of TCS on Category 1 to explain the impaired oxidative metabolism and electrophysiological derangements within the tethered spinal cord, which is the primary intrinsic cause of the dysfunction. Furthermore, they extend the discussion to the extrinsic (outside the spinal cord) factors and other complex conditions that mimic TCS.
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