SOCS2 Balances Metabolic and Restorative Requirements during Liver Regeneration

After significant injury, the liver must maintain homeostasis during the regenerative process. We hypothesized the existence of mechanisms to limit hepatocyte proliferation after injury to maintain metabolic and synthetic function. A screen for candidates revealed suppressor of cytokine signaling 2 (SOCS2), an inhibitor of growth hormone (GH) signaling, was strongly induced after partial hepatectomy. Using genetic deletion and administration of various factors we investigated the role of SOCS2 during liver regeneration. SOCS2 preserves liver function by restraining the first round of hepatocyte proliferation after partial hepatectomy by preventing increases in growth hormone receptor (GHR) via ubiquitination, suppressing GH pathway activity. At later times, SOCS2 enhances hepatocyte proliferation by modulating a decrease in serum insulin-like growth factor 1 (IGF-1) that allows GH release from the pituitary. SOCS2, therefore, plays a dual role in modulating the rate of hepatocyte proliferation. In particular, this is the first demonstration of an endogenous mechanism to limit hepatocyte proliferation after injury.     

Determinants of Slow Walking Speed in Ambulatory Patients Undergoing Maintenance Hemodialysis

Walking ability is significantly lower in hemodialysis patients compared to healthy people. Decreased walking ability characterized by slow walking speed is associated with adverse clinical events, but determinants of decreased walking speed in hemodialysis patients are unknown. The purpose of this study was to identify factors associated with slow walking speed in ambulatory hemodialysis patients. Subjects were 122 outpatients (64 men, 58 women; mean age, 68 years) undergoing hemodialysis. Clinical characteristics including comorbidities, motor function (strength, flexibility, and balance), and maximum walking speed (MWS) were measured and compared across sex-specific tertiles of MWS. Univariate and multivariate logistic regression analyses were performed to examine whether clinical characteristics and motor function could discriminate between the lowest, middle, and highest tertiles of MWS. Significant and common factors that discriminated the lowest and highest tertiles of MWS from other categories were presence of cardiac disease (lowest: odds ratio [OR] = 3.33, 95% confidence interval [CI] = 1.26–8.83, P<0.05; highest: OR = 2.84, 95% CI = 1.18–6.84, P<0.05), leg strength (OR = 0.62, 95% CI = 0.40–0.95, P<0.05; OR = 0.57, 95% CI = 0.39–0.82, P<0.01), and standing balance (OR = 0.76, 95% CI = 0.63–0.92, P<0.01; OR = 0.81, 95% CI = 0.68–0.97, P<0.05). History of fracture (OR = 3.35, 95% CI = 1.08–10.38; P<0.05) was a significant factor only in the lowest tertile. Cardiac disease, history of fracture, decreased leg strength, and poor standing balance were independently associated with slow walking speed in ambulatory hemodialysis patients. These findings provide useful data for planning effective therapeutic regimens to prevent decreases in walking ability in ambulatory hemodialysis patients.     

The AtXTH28 Gene, a Xyloglucan Endotransglucosylase/Hydrolase, is Involved in Automatic Self-Pollination in Arabidopsis thaliana

Successful automatic self-pollination in flowering plants isdependent on the correct development of reproductive organs.In the stamen, the appropriate growth of the filament, whichlargely depends on the mechanical properties of the cell wall,is required to position the anther correctly close to the stigmaat the pollination stage. Xyloglucan endotransglucosylase/hydrolases(XTHs) are a family of enzymes that mediate the constructionand restructuring of xyloglucan cross-links, thereby controllingthe extensibility or mechanical properties of the cell wallin a wide variety of plant tissues. Our reverse genetic analysishas revealed that a loss-of-function mutation of an ArabidopsisXTH family gene, AtXTH28, led to a decrease in capability forself-pollination, probably due to inhibition of stamen filamentgrowth. Our results also suggest that the role of AtXTH28 inthe development of the stamen is not functionally redundantwith its closest paralog, AtXTH27. Thus, our finding indicatesthat AtXTH28 is specifically involved in the growth of stamenfilaments, and is required for successful automatic self-pollinationin certain flowers in Arabidopsis thaliana.     

Cultural aspects of Graphiola phoenicis

An experiment was carried out to study the cultural behaviour ofGraphiola phoenicis ((Moug.)Poiteau because nothing has been known on the morphological and physiological characters on artificial media. The daughter cell sprouted out from the sporidium ofG. phoenicis reproduced by budding so that a pinkish yeast-like colony resulted on the agar medium. Physiological characters of the isolate were investigated and a discussion on the possible phylogenetical relationships to the reddish yeast was given.

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Zusammenfassung Das kulturelle Verhalten vonGraphiola phoenicis (Moug.)Poiteau wurde untersucht, da nichts von ihrer morphologischen und physiologischen Charakteristik an künstlichen Kulturnährboden bekannt war. Die Tochterzellen keimten vomSporidium vonG. phoenicis und reproduzierten sich durch Sproßzellen. Das Resultat war eine blaßrote, hefe-ähnliche Kolonie an dem Nährmedium. Die physiologische Charakteristik des Stammes wurde untersucht und die mögliche, phylogenetische Beziehung zu den Rothefen diskutiert.

     

The possible existence of a heat-stable alkaline proteinase (HAP) in rat skeletal muscle

1. A unique caseinolytic activity was found in the crude extract from chicken and rat skeletal muscle. Hardly any activity was detected at physiological assay temperatures at pH 8.0 but did well at around 60 degrees C. 2. The activity partially purified from rat skeletal muscle showed optimum pH at around 8.0 at 60 degrees C. It hardly hydrolyzed casein below 50 degrees C, but in the presence of 5 M urea it showed relatively high activity at 30 degrees C. The activity was completely stable at 50 degrees C for 1 hr. 3. The activity seems to be contained in a high mol. wt (450,000) protein from the elution volume and is due to cysteine proteinase from the effect of inhibitors. 4. The above properties agreed with those of the heat-stable alkaline proteinase (HAP) of fish purified homogeneously by electrophoresis. This seems to suggest that HAP may also exist in rat skeletal muscle.     

The genes for human alcohol dehydrogenases beta 1 and beta 2 differ by only one nucleotide

Allelic differences at the alcohol dehydrogenase (ADH) and aldehyde dehydrogenase loci may have an important role in an individual's alcohol sensitivity. We have cloned and sequenced all nine exons of an ADH2(2) allele which codes for an 'atypical' ADH, ADH beta 2. Our sequence data shows that the histidine at residue 47 of ADH beta 2 is encoded by CAC. Surprisingly, no silent substitution was found between the coding regions of ADH2(1) [Duester, G., Smith, M., Bilanchone, V. & Hatfield, G. W. (1986) J. Biol. Chem. 261, 2027-2033.] and ADH2(2) alleles over the 1122 nucleotide sites.     

Fractal property of eye movements in schizophrenia

 On the basis of a temporal model of animal behavior we conducted temporal analysis of eye movements in schizophrenic subjects (n=10) and normal controls (n=10). We found a fractal property in schizophrenic subjects, the fixation time of eye movement during reading ambiguous and difficult sentences showing a clear inverse power law distribution. An exponential distribution of a nonfractal nature was found in normal controls. Received: 21 July 1995/Accepted in revised form: 30 April 1996     

Quercetin metabolites and protection against peroxynitrite-induced oxidative hepatic injury in rats

Quercetin has strong antioxidant potency. Quercetin-3′-O-sulphate (Q3′S) and quercetin-3-O-glucuronide (Q3GA) are the main circulating metabolites after consumption of quercetin-O-glucoside-rich diets by humans. However, information about how these quercetin metabolites function in vivo is limited. Hence, this study evaluated the efficacy of Q3′S and Q3GA for the protection of oxidative injury using in vitro and in vivo experiments. Peroxynitrite-mediated hepatic injury in rats was induced by administration of galactosamine/lipopolysaccharide (GalN/LPS). Twenty-four hours after GalN/LPS treatment, plasma ALT and AST levels δ increased significantly. However, pretreatment with 4^G-α-D-glucopyranosyl rutin, a quercetin glycoside (30 mg/kg body weight), prevented these increases and reduced nitrotyrosine formation, indicating that consumption of quercetin glycosides prevent oxidative hepatotoxicity. Moreover, physiological levels of Q3′S and Q3GA (1 µM) effectively prevented peroxynitrite-induced nitrotyrosine formation in human serum albumin in in vitro experiments. These findings indicate peroxynitrite-induced oxidative hepatotoxicity is protected by the in vivo metabolites of quercetin, Q3′S and Q3GA.