Isolation and characterization of parenchymal cells from experimentally induced macronodular rat liver cirrhosis

Hepatocytes were isolated from thioacetamide (TAA)-induced macronodular cirrhotic rat livers by a collagenase perfusion method. In the content of cellular metabolites, fatty acid uptake and lipid secretion there were no substantial differences compared with cells isolated from micronodular cirrhosis described previously. In contrast to isolated hepatocytes from normal livers those from macronodular cirrhosis had a lowered cellular content of triglycerides, phospholipids and cholesterol but not of cholesterol esters and free fatty acids. In macronodular cirrhosis hepatocytes of hypertrophic type, rich in cell organelles, can be distinguished ultrastructurally from those with signs of atrophy and degeneration. Immediately after isolation many hepatocytes isolated from macronodular cirrhosis showed plasma membrane blebbing. Whereas the blebbing was without recognizable effects on the fine structure of the isolated hepatocytes of the hypertrophic type, in the more atrophic ones some mitochondria were swollen. In addition, morphological analysis of the crude and purified suspensions revealed a partial selection of the hypertrophic cells during the isolation procedure, presumably due to a more labile state of those cells which showed signs of atrophy and degeneration. When stabilized in the suspension medium, however, the hepatocytes maintained complex metabolic functions for at least 2 h. Thus, the method described allows the isolation of parenchymal cells from TAA-induced macronodular cirrhotic livers for studying ultrastructural and biochemical alterations in hyperregenerative experimental liver cirrhosis.     

Reducing acetylated tau is neuroprotective in brain injury

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Flamingo breeding: The role of group displays

Group displays in flamingos have been presumed to play a role in stimulating synchronous nesting and in facilitating pair formation. This study compares the group displays and breeding success of a captive flock of Caribbean flamingos (Phoenicopterus ruber ruber) at the National Zoological Park between 2 years: the frequency and synchrony of group displays were measured for a flock of 17 in 1988 and then again in 1989 after flock size was increased to 21. In 1989 the rate of occurrence of display activity increased 48%, the synchrony of group displays increased 100%, the frequency of mounts and copulations almost doubled, and for the first time in the flock's history two fertile eggs were produced. The use of sprinklers to simulate rain had no effect on the group displays. The amount of naturally occurring rainfall in 1989 was almost twice that in 1988. The increased frequency and synchrony of group displays could be attributed to increased flock size, change in sex ratio, addition of strange individuals, or increased rainfall. This study, however, provides evidence for a relationship between behavioral stimulation from group displays and components of breeding success in flamingos.     

Lunar-Rhythmic Molting in Laboratory Populations of the Noble Crayfish Astacus astacus (Crustacea,Astacidea): An Experimental Analysis

Juvenile noble crayfish, Astacusastacus (Crustacea, Astacidea) in the second year of age were kept in the laboratory for a twelve-month period under continuing “summer conditions” (LD 16:8, 19°C). Molting processes in this population could be synchronized by artificial moonlight cycles. Peaks of exuviations occurred at “new moons”. Males showed a slightly higher degree of synchronization than females. A phase-shift of the artificial lunar cycle in relation to the natural cycle resulted in a corresponding shift of the molting cycle. This clearly demonstrates that changes in the nocturnal light regime provide the primary external information for the lunar-monthly molting rhythm. There is a first indication that lunar photic stimuli do not act directly but as a zeitgeber which entrains an endogenous molting rhythm to the lunar cycle. Moreover, the results of the long-term experiments suggest that the hibernal resting period of A . astacus in the field (no molts between October and April) may also involve some endogenous programming. Continuing artificial summer conditions can delay but not completely suppress this resting period. The adaptive significance of the phenomena and how the findings may be applied to improve the management of crowded crayfish stocks are discussed.     

ADHD symptoms in healthy adults are associated with stressful life events and negative memory bias

Stressful life events, especially Childhood Trauma, predict ADHD symptoms. Childhood Trauma and negatively biased memory are risk factors for affective disorders. The association of life events and bias with ADHD symptoms may inform about the etiology of ADHD. Memory bias was tested using a computer task in N = 675 healthy adults. Life events and ADHD symptoms were assessed using questionnaires. The mediation of the association between life events and ADHD symptoms by memory bias was examined. We explored the roles of different types of life events and of ADHD symptom clusters. Life events and memory bias were associated with overall ADHD symptoms as well as inattention and hyperactivity/impulsivity symptom clusters. Memory bias mediated the association of Lifetime Life Events, specifically Childhood Trauma, with ADHD symptoms. Negatively biased memory may be a cognitive marker of the effects of Childhood Trauma on the development and/or persistence of ADHD symptoms.     

Development of a radioactive protein A-based assay for analysis of surface protein expression in gram-positive bacteria.

This paper describes an immunochemical method which uses radioactive protein A for the detection and analysis of streptococcal M6 protein epitopes on the surface of recombinant Streptococcus gordonii. With this assay, recombinant S. gordonii cells expressing a portion of the M6 protein on their surfaces show a 75-fold increase in bound radioactivity over cells of the control S. gordonii parental strain. Furthermore, use of the assay to monitor the amount of M6 protein present on the surface of the S. gordonii recombinant during growth in culture demonstrated that expression is highest at late log phase, with the protein being sloughed off during stationary phase. This simple assay allows analysis of surface protein without any protein purification or sophisticated instrumentation. As such, it should be broadly applicable to following the expression of most surface-accessible bacterial proteins.     

Haemocompatibility of coronary catheters.

BACKGROUND: Unwanted side-effects like thrombotic-thromboembolic processes accompany the intravascular use of catheters. The influence of the physico-chemical properties of the catheter materials on these processes is not completely understood. METHODS: The haemocompatibility of angiography-catheters (n = 10) (Super Torque Plus, CORDIS, Johnson & Johnson company) was examined in a perfusion-model filled with platelet-rich plasma and either compared to a non-thrombogenic (silicon-tube) or to a thrombogenic surface (glass). As test-parameters the number of single circulating thrombocytes, of circulating platelet-aggregates, of circulating activated thrombocytes (CD62) and the thrombin generation (thrombin antithrombin III-complexes) were evaluated. RESULTS: None of the test-parameters showed differences between the non-thrombogenic control-system and the angiography-catheters. Both systems, however, differed significantly and relevantly from the system filled with the glass-beads (the thrombogenic control-systems). CONCLUSION: With respect to the platelet reactivity angiography-catheters of the examined type can therefore be regarded as non-thrombogenic or haemocompatible.