Purification of malted-barley endo-β-D-glucanases by ion-exchange chromatography: some properties of an endo-barley-β-D-glucanase

Two endo-β-D-glucanases which act, respectively, on (1→3)-β-D-glucans and barley β-D-glucan have been isolated from malted barley, and purified by ion-exchange chromatography. The latter enzyme is highly specific for barley β-D-glucan, and has no action on either (1→3)- or (1→4)-β-D-glucans. It will also act on dyed barley-β-D-glucan. Certain group-specific reagents inhibit the endo-barley-β-D-glucanase and the endo-(1→3)-β-D-glucanase to similar extents.     

Energy metabolism in rat brain in vivo studied by 31P nuclear magnetic resonance: changes during postnatal development

The energy metabolism in rat brains during postnatal development was followed by in vivo 31P NMR. Using a small surface coil (from several to 10 mm in diameter) placed at the head of a conscious rat, high-energy phosphate compounds in the brain and the steady-state kinetics among them were measured. The cellular contents of some phosphate compounds changed widely during the period of postnatal cell growth from age 10 to 20 days. During the same period, the cellular activity of creatine kinase increased by a factor of more than 5 as measured by a saturation transfer technique. The in vivo value of the creatine/creatine phosphate ratio was estimated from the in vitro value (in perchloric acid extracts), assuming that the in vivo ratio of the creatine and creatine phosphate pool over the ATP and ADP pool was the same as the corresponding in vitro value. From the creatine/creatine phosphate ratio thus obtained, the value of the cytosolic ATP/ADP ratio was estimated for brains of adult rats and neonate rats. Unexpectedly the value in the latter was found to be smaller.     

Cigarette Smoking and Platelet Aggregation

The influence of cigarette smoking on platelet aggregation was studied in habitual and non-habitual smokers. The results indicate that habitual smokers have a greater tendency to platelet aggregation than do non-habitual smokers. Acute effects of cigarette smoking were, however, not significant. The nucleotide content and the serotonin content of the platelets were analyzed. The adenosine nucleotide and serotonin contents were similar in smokers and non-smokers in the control state and neither showed significant changes on cigarette smoking. There were significant correlations between the control concentrations of the various nucleotides in both groups and there were even higher correlations after smoking. Platelet aggregation bore no demonstrable relationship to the nucleotide or serotonin contents of the platelet. We conclude that the long-term effect of smoking is probably more important than the acute effect.     

An investigation of adhesion and detachment in slime mould amoebae using columns of hydrophobic beads

Vegetative amoebae of Dictyostelium discoideum (strain AX2) adhere to columns of hydrophobic beads (Bio-Beads SM-2) which have been coated with axenic growth medium. This binding is blocked by sodium azide and other inhibitors of aerobic respiration. Bound cells are not detached by lowering the temperature but they can be eluted from the column by including azide in the medium. However, this effect is critically influenced by temperature. The elution profiles become progressively shallower as the temperature is lowered. The profiles represent a set of probability distributions whose means and variances increase with decreasing temperature. Below 20 degrees C, the mean time to cell detachment is a linear function of temperature. A statistical model of this azide-stimulated detachment has been developed which closely predicts the real data. It assumes that each amoeba has k binding sites whose stochastically independent behaviour is governed by a parameter theta; the mean time to detachment of each site is 1/theta. Both parameters have been estimated. The value of k is close to 3 and does not vary with temperature below 20 degrees C. In contrast, theta varies in such a way that the value of 1/theta increases linearly with decreasing temperature, so paralleling the behaviour of the mean cell detachment time.     

In Vivo Production of Neuraminidase by Pasteurella haemolytica in Market Stressed Cattle After Natural Infection

Pasteurella haemolytica (Ph) is the most important cause of the bovine acute fibrinohemorrhagic pneumonia that occurs in market stressed calves after shipment to feedyards. Recent characterization of neuraminidase production by these organisms has shown that all 16 serotypes produce an immunologically similar form of the enzyme. Anti-neuraminidase antibody against PhA1 and PhA6 was determined in 101 2- to 5-month-old calves, on their farms of origin, at the order buyer barn (OBB), and through 28 days in the feedyard. Half of the calves were vaccinated with a killed Ph serotype-A1 (PhA1) product. Nasal secretion and tonsil wash specimens were cultured for Ph and Pasteurella multocida (Pm). Serum antibody against PhA1 and PhA6 was measured by indirect hemagglutination (IHA), and anti-neuraminidase antibody was determined by the neutralization assay. At the feedyard, 73 calves had respiratory tract disease. IHA values ranged between 1:2 and 1:1024 for PhA1 and between 1:2 and 1:512 for Ph serotype A6 (PhA6). Forty-two, 24, and 28% of the calves were infected with PhA1, PhA6, and Pm, respectively. Ninety-six percent of the calves experienced an increase in anti-PhA1 neuraminidase antibody when sera drawn on feedyard day 28 were compared with sera drawn on the farm. These data demonstrate that the enzyme neuraminidase is produced in vivo in market stressed cattle after a natural Ph infection. Received: 23 March 1998 / Accepted: 4 May 1998