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.     

Purification of hepatitis B virus gene X product synthesized in Escherichia coli and its detection in a human hepatoblastoma cell line producing hepatitis B virus

A fused gene containing 94% of the hepatitis B virus (HBV) open reading frame X was expressed in Escherichia coli, and its 17-kDa product was purified by ion-exchange chromatography. Antibody elicited against the X-gene product reacted with materials proximal to the nuclear membrane of a human hepatoblastoma cell line producing HBV particles. No such reaction was observed with the same cell line that did not produce HBV particles.     

Identification of cellular components required for SV40 DNA replication in vitro

To investigate the cellular proteins involved in simian virus 40 (SV40) replication, extracts derived from human 293 cells have been fractionated into multiple components. When such fractions are combined with the virus-encoded T antigen (TAg) and SV40 origin containing plasmid DNA, efficient and complete replication is achieved, while each fraction alone is inactive. At present, a minimum of eight such cellular components have been identified. Previous experiments have demonstrated one of these to be the cell-cycle-regulated proliferating-cell nuclear antigen (PCNA). As PCNA has been identified as a processivity factor for DNA polymerase delta, we suggest that both polymerases alpha and delta are involved in this system. Three further fractions have been identified. One is a partially purified fraction which, under certain conditions, is required with TAg for the formation of a pre-synthesis complex of proteins at the replication origin. The second of these factors, RF-A, is a complex of three polypeptides which may function as a eucaryotic SSB. The third, RF-C, is a factor which is required, with PCNA, for coordinated leading- and lagging-strand synthesis at the replication fork. Complete synthesis and segregation of the daughter molecules also requires the presence of topoisomerases I and II. These results suggest a model for DNA synthesis which involves multiple stages prior to and during replicative DNA synthesis.     

Analysis of feeding mechanism in a pitcher ofNepenthes hybrida

The process of digestion of captured feeds in a pitcher, an insect-trapping organ, ofNepenthes was studied. Changes in bacterial population, pH and NH₄ ⁺ concentrations in pitcher juice were examined. Strong activities of both acid- and alkaline phosphatase, phosphoamidase, esterase C4 and esterase C8 were found in the pitcher juice. Optimum pH of proteases in the juice and those secreted from bacteria showed pH 3.0 and pH 8.0–9.0, respectively. Twenty six strains of bacteria were isolated from 4 pitchers: 10 strains were gram positive, 16 strains were gram negative (10 strains had casein hydrolase activity). A proton excretion was induced by NH₄ ⁺ released from the added solutions, and accordingly, the pH of the solutions fell. As a simulation model of the digestion process of feeds in pitcher juice and polypeptone solution was added into the washed pitcher. A good correlation was found among the NH₄ ⁺ concentration, pH and bacterial cell titer.     

Loss of chloroplast-localized NAD kinase causes ROS stress in Arabidopsis thaliana

Journal of Plant Research - Chloroplast-localized NAD kinase (NADK2) is responsible for the production of NADP+, which is an electron acceptor in the linear electron flow of photosynthesis. The...     

Switching dynamics and the transient memory storage in a model enzyme network involving Ca2+/calmodulin-dependent protein kinase II in synapses

 The signal processing through a chain of phosphorylation-dephosphorylations mediated by a pair of enzymes, Ca²⁺/calmodulin-dependent protein kinase II and the associated phosphatase, is formulated as a non-autonomous dynamical system in the framework of non-autocatalytic, intraholoenzyme reaction dynamics. A classification of switching characteristics of the system is made in the parameter space comprising the three controllable system parameters: an input-pulse intensity and initial concentrations of the two associated enzymes. It is found that a region of parameter space exists termed the transition zone, that exhibits a quasi-switching behaviour characterized by a signal storage time being prolonged by more than several orders of magnitude (10⁴ times in certain cases) for the increase of two orders of magnitude in the input signal intensity. The effect of alterations of certain rate constants on the quasi-switching property is explored. It is numerically demonstrated that the Ca²⁺/calmodulin-dependent kinase II-related phosphatase is the most important key enzyme for regulating the signal storage time. Received: 25 April 1994/Accepted in revised form: 16 December 1994