OBJECTIVE: Repeated administration of mannitol in the setting of large hemispheric infarction is a controversial and poorly defined therapeutic intervention. This study was performed to examine the effects of multiple-dose mannitol on a brain edema after large hemispheric infarction. METHODS: A middle cerebral artery was occluded with the rat suture model for 6 hours and reperfused in 22 rats. The rats were randomly assigned to either control (n=10) or the mannitol-treated group (n=12) in which intravenous mannitol infusions (0.8 g/kg) were performed six times every four hours. After staining a brain slice with 2,3,5-triphenyltetrazolium chloride, the weight of hemispheres, infarcted (IH) and contralateral (CH), and the IH/CH weight ratio were examined, and then hemispheric accumulation of mannitol was photometrically evaluated based on formation of NADH catalyzed by mannitol dehydrogenase. RESULTS: Mannitol administration produced changes in body weight of -7.6+/-1.1%, increased plasma osmolality to 312+/-8 mOsm/L. It remarkably increased weight of IH (0.77+/-0.06 gm versus 0.68+/-0.03 gm : p<0.01) and the IH/CH weight ratio (1.23+/-0.07 versus 1.12+/-0.05 : p<0.01). The photometric absorption at 340 nm of the cerebral tissue in the mannitol-treated group was increased to 0.375+/-0.071 and 0.239+/-0.051 in the IH and CH, respectively from 0.167+/-0.082 and 0.162+/-0.091 in the IH and CH of the control group (p<0.01). CONCLUSION: Multiple-dose mannitol is likely to aggravate cerebral edema due to parenchymal accumulation of mannitol in the infarcted brain tissue.
Absorption ; Animals ; Body Weight ; Brain ; Brain Edema* ; Cerebral Infarction ; Infarction ; Infarction, Middle Cerebral Artery* ; Mannitol Dehydrogenases ; Mannitol* ; Middle Cerebral Artery* ; Models, Animal* ; NAD ; Osmolar Concentration ; Plasma ; Rats* ; Sutures

D-Mannitol has wide applications in food, pharmaceutical, and chemical industries. In this study, we constructed a genetically stable Escherichia coli strain for D-mannitol production by integrating mannitol dehydrogenase (mdh) and fructose permease (fupL) genes of Leuconostoc pseudomesenteroides ATCC 12291 into chromosome of E. coli ATCC 8739 and inactivating other fermentation pathways (including pyruvate formate-lyase, lactate dehydrogenase, fumarate reductase, alcohol dehydrogenase, methylglyoxal synthase and pyruvate oxidase). Using mineral salts medium with glucose and fructose as carbon sources, the engineered strain could produce 1.2 mmol/L D-mannitol after anaerobic fermentation for 6 days. Based on the coupling of cell growth and D-mannitol production, metabolic evolution was used to improve D-mannitol production. After evolution for 80 generations, D-mannitol titer increased 2.6-fold and mannitol dehydrogenase activity increased 2.8-fold. Genetically stable strains constructed in this work could ferment sugars to produce D-mannitol without the addition of antibiotics, inducers and formate, which was favorable for industrial production.
Escherichia coli ; genetics ; metabolism ; Fermentation ; Industrial Microbiology ; methods ; Leuconostoc ; enzymology ; Mannitol ; metabolism ; Mannitol Dehydrogenases ; genetics ; Metabolic Engineering ; methods ; Monosaccharide Transport Proteins ; genetics

OBJECTIVETo compare the transcription difference of the mannitol PTS genes between epidemic and non-epidemic strains of Vibrio cholerae El Tor in mannitol ferment tests.

METHODSGrowth curves of 10 epidemic strains (slow-ferment) and 10 non-epidemic strains (rapid-ferment) of Vibrio cholerae were detected in the process of fermentation test, and the transcriptional level of mannitol PTS operon of these strains were determined with quantitative reverse-transcriptional PCR.

RESULTSAfter 4 hours of test, the non-epidemic strains became positive and the average growth density of the non-epidemic strains was higher than that of the epidemic strains; however, some were still lower than the epidemic strains. In contrast, at the eighth hour of test, when epidemic strains got positive, they showed higher average growth density. Compared to the epidemic strains, the transcription of mannitol PTS genes of the non-epidemic strains were much more active at the 1st and 2nd hour and were lower at the 4th and 8th hour.

CONCLUSIONSThe difference of mannitol PTS operon transcription level should be an important feature to identify the epidemic and non-epidemic strains of Vibrio cholerae, which directly influences the mannitol fermentation rate during the test. The growth rate is not a key factor that affect such difference.

Bacterial Proteins ; genetics ; Gene Expression Regulation, Bacterial ; Mannitol ; metabolism ; Operon ; Phosphoenolpyruvate ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; methods ; Sugar Alcohol Dehydrogenases ; metabolism ; Transcription, Genetic ; Vibrio cholerae ; classification ; genetics ; metabolism