Tat-Dependent Heterologous Secretion of Recombinant Tyrosinase by Pseudomonas fluorescens Is Aided by a Translationally Fused Caddie Protein.

Tyrosinase is a monooxygenase that catalyzes both the hydroxylation of p-hydroxyphenyl moieties to o-catechols and the oxidation of o-catechols to o-quinones. Apart from its critical functionality in melanogenesis and the synthesis of various neurotransmitters, this enzyme is also used in a variety of biotechnological applications, most notably mediating covalent cross-linking between polymers containing p-hydroxyphenyl groups, forming a hydrogel. Tyrosinases from the genus Streptomyces are usually secreted as a complex with their caddie protein. In this study, we report an increased secretion efficiency observed when the Streptomyces antibioticus tyrosinase gene melC2 was introduced into Pseudomonas fluorescens along with its caddie protein gene melC1, which has the DNA sequence for the Tat (twin-arginine translocation) signal.IMPORTANCE We observed that the S. antibioticus extracellular tyrosinase secretion level was even higher in its nonnatural translationally conjugated fusion protein form than in the natural complex of two separated polypeptides. The results of this study demonstrate that tyrosinase-expressing P. fluorescens can be a stable source of bacterial tyrosinase through exploiting the secretory machinery of P. fluorescens.

Factors associated with improvement or decline in cognitive function after an ischemic stroke in Korea: the Korean stroke cohort for functioning and rehabilitation (KOSCO) study.

BACKGROUND: We conducted a prospective cohort study to investigate prevalence of poststroke cognitive impairment at 3 and 12 months after stroke onset and identify clinical and demographic factors associated with improvement or decline in cognitive function between 3 months and 12 months. METHODS: We analyzed the cognitive assessments of total patients and patients older than 65 years separately. All patients with an ischemic stroke were divided into normal cognitive group (NCG) and impaired cognition group (ICG) by using a cutoff score on the Korean Mini-Mental State Examination (K-MMSE). Patients were additionally classified into 3 subgroups according to the changes in their K-MMSE scores between 3 and 12 months: Stable group with K-MMSE scores changes ranging from -2 to +2 points (-2 ≤ △MMSE ≤ +2); converter group with increase more than 3 points (3 ≤ △MMSE); and reverter group with decrease more than 3 points (-3 ≤ △MMSE). We also analyzed factors affecting cognitive change from 3 months to 12 months among the 3 groups including baseline medical record, stroke and treatment characteristics, and various functional assessments after 3 months. RESULTS: This study included 2,625 patients with the first time ischemic stroke. Among these patients, 1,735 (66.1%) were classified as NCG, while 890 patients (33.9%) were belonged to the ICG at 3 month. Within the NCG, 1,460 patients (82.4%) were stable group, 93 patients (5.4%) were converter group, and 212 patients (12.2%) were reverter group at 12 months onset. Within the ICG group, 472 patients (53.0%) were stable group, 321 patients (36.1%) were converter group, and 97 patients (10.9%) were reverter group. When different factors were investigated, the three subgroups in NCG and ICG showed significant different factors affecting cognitive function from 3 to 12 month. CONCLUSIONS: The prevalence of cognitive impairment showed difference between 3,12 months. To analyze the cognitive change from 3 month to 12 month, the proportion stable group was dominant in NCG and converter group was higher in ICG. By investigating the influencing factors from each group, we were able to identify the predictors including the age factor.

Low serum TNF-related apoptosis-inducing ligand (TRAIL) levels are associated with acute ischemic stroke severity.

BACKGROUND: TNF-related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor receptor superfamily and its serum level is known to be closely associated with future cardiovascular events and prognosis of various cardiovascular diseases. We investigated whether serum TRAIL levels are associated with the severity of acute ischemic stroke and specific stroke subtype. METHODS: We used an enzyme-linked immunosorbent assay to measure the serum TRAIL levels of 293 patients with acute ischemic stroke within 7 days of onset. Stroke subtype was classified as large artery atherosclerosis, cardioembolism, small vessel occlusion and other determined etiology. We used National Institute of Health Stroke Scale (NIHSS) score of first hospital day and stroke volume on diffusion-weighted imaging within 7 days of stroke onset for measuring the severity of acute ischemic stroke. RESULTS: The level of serum TRAIL showed significant negative correlations with NIHSS score and stroke volume. Serum TRAIL levels significantly decreased as the tertile of NIHSS score and stroke volume increased. The relative risk of patients with serum TRAIL<64.0 pg/mL for the presence of highest tertile of NIHSS score was significantly increased (adjusted OR [95%CI]; 7.07 [3.64-13.74]). Regarding stroke volume, the relative risk of patients with serum TRAIL<71.5 pg/mL for the presence of highest tertile of stroke volume was also significantly increased (adjusted OR [95%CI]; 2.81 [1.61-4.92]). There are no significant differences of serum TRAIL level among stroke subtypes. CONCLUSIONS: Low serum TRAIL levels were significantly associated with the acute ischemic stroke severity. This finding suggests that serum TRAIL might also have a role in acute ischemic stroke as well as other cardiovascular diseases.

Nocturnal frontal lobe epilepsy presenting as obstructive type sleep apnea.

A 20-year-old man presented with sleep apnea. Polysomnography was performed and it revealed nine apneas and two hypopneas. Contrary to typical apnea, however, rhythmic epileptiform discharges appeared at bifrontal area on EEG just before the start of apnoea. Video-EEG monitoring was performed to classify these events, and to evaluate the relationship of apnoea and ictal discharge. Ictal EEG revealed paroxysmal fast activity over the bifrontal area. Ictal SPECT showed hyperperfusion in right frontal area. Given these findings, we concluded that these events were epileptic seizures presenting as obstructive sleep apnea. Antiepileptic medication was initiated, and the events were decreased. This case demonstrates that nocturnal frontal love epilepsy may be the potential cause of obstructive sleep apnea (OSA).