Exocrine pancreatic insufficiency in pigeons.

Exocrine pancreatic insufficiency (EPI) is a well-studied syndrome in domestic animals. EPI occurs when severe progressive loss of tubulo-acinar tissue from atrophy or inflammatory destruction results in insufficient secretion of digestive enzymes and clinical signs of malabsorption. However, the literature on EPI in birds is limited. The syndrome has been previously described in several cases where the diagnosis was based on clinical signs due to malabsorption-like light-coloured voluminous faeces, voracious appetite, coprophagia and weight loss, and on the response to treatment with pancreatic enzyme formulas. To enable a more scientific approach to the diagnosis of pancreatic functional disorders in pigeons, reference values of plasma amylase (382 to 556 IU/l), lipase (0 to 5 IU/l), and faecal activities of amylase (13 to 16 IU/l) and trypsin (11 to 14 IU/l) were determined in 24 adult pigeons. A case of EPI in a racing pigeon (Columba livia domestica) is reported, based on the clinical signs and the measurement of faecal amylase and trypsin activity.     

Anxiety Profiles of Mice Selectively Bred for Intermale Aggression

In the present study we compared genetically selected aggressive (TA) and nonaggressive (TNA) male mice, as well as males from an unselected control line (SW), in three tests of anxiety: the elevated plus-maze, the light-dark box, and the staircase test. Males were tested repeatedly for 3 days. In all three tests TA males were found to be more active and less anxious than TNA males, with SW males showing more or less intermediate scores. Furthermore, repeated plus-maze testing induced anxiety-like behavior in both TA and TNA mice, whereas repeated testing in the light-dark and staircase paradigms resulted in different responses. Whereas TNA animals were found to be stable, TA animals showed habituation on the second and third day of testing. The obtained data support the conclusion that a higher-level offensive aggression entails lower level of anxiety.     

Behavioral analysis of the saccharin deprivation effect in rats

The deprivation effect (DE)--an increase in the level of free-choice consumption of alcohol after a period of forced abstinence--may reflect relapselike drinking and be relevant for modeling alcohol abuse. However, the behavioral mechanisms of the DE are unclear. In these experiments, rats had unlimited free-choice access to water and saccharin-containing solutions and underwent repeated episodes of saccharin deprivation. It was found that DE magnitude correlates positively with the deprivation phase duration, expression of the DE is highly context dependent, and the DE can be prevented by extinguishing response to the saccharin-associated stimuli. Thus, DE procedures may be useful for studying the effects of continued exposure to stimuli associated with various primary reinforcers such as drugs of abuse.     

Metallo-beta-lactamase VIM-2 in clinical isolates of Pseudomonas aeruginosa from Portugal

Resistance to carbapenems is emerging, and it is a great problem to therapeutics. Three isolates of Pseudomonas aeruginosa from a Portuguese hospital identified in urine and sputum, in 1995, presented a high-level resistance to imipenem (> 32 mg/L). Afterward, one isolate of P. aeruginosa recovered from urine of an ambulatory patient in 1998 showed high resistance to imipenem and meropenem. The resistance to carbapenems in these strains was associated with the production of a class B beta-lactamase, as was demonstrated by imipenem hydrolysis and inhibition by EDTA. Using primers described for bla(IMP) and bla(VIM), the amplification of the latter was observed in all isolates and a VIM-2 metallo-enzyme was identified. The pulsed-field gel electrophoresis (PFGE) patterns of these isolates were indistinguishable, suggesting dissemination to the community of this VIM-2 producer.     

Molecular mechanism of kNBC1–carbonic anhydrase II interaction in proximal tubule cells

We have recently shown that carbonic anhydrase II (CAII) binds in vitro to the C-terminus of the electrogenic sodium bicarbonate cotransporter kNBC1 (kNBC1-ct). In the present study we determined the molecular mechanisms for the interaction between the two proteins and whether kNBC1 and CAII form a transport metabolon in vivo wherein bicarbonate is transferred from CAII directly to the cotransporter. Various residues in the C-terminus of kNBC1 were mutated and the effect of these mutations on both the magnitude of CAII binding and the function of kNBC1 expressed in mPCT cells was determined. Two clusters of acidic amino acids, L⁹⁵⁸DDV and D⁹⁸⁶NDD in the wild-type kNBC1-ct involved in CAII binding were identified. In both acidic clusters, the first aspartate residue played a more important role in CAII binding than others. A significant correlation between the magnitude of CAII binding and kNBC1-mediated flux was shown. The results indicated that CAII activity enhances flux through the cotransporter when the enzyme is bound to kNBC1. These data are the first direct evidence that a complex of an electrogenic sodium bicarbonate cotransporter with CAII functions as a transport metabolon.     

Differential scanning calorimetric study of the complexes of modified myosin subfragment 1 with ADP and vanadate or beryllium fluoride

Summary The effects of various modifications of rabbit skeletal myosin subfragment 1 on thermal denaturation of subfragment 1 in ternary complexes with Mg-ADP and orthovanadate (V_i) or beryllium fluoride (BeF_x) have been studied by differential scanning calorimetry. It has been shown that specific modifications of SH₁ group of Cys-707 by different sulfhydryl reagents, trinitrophenylation of Lys-83, and reductive methylation of lysine residues promote the decomposition of the S1·ADP·V_i complex and change the character of structural transitions of the subfragment 1 molecule induced by the formation of this complex, but they have much less or no influence on subfragment 1 thermal stability in the S1·ADP·BeF_x complex. Thus, the differential scanning calorimetric studies on modified subfragment 1 preparations reveal a significant difference between S1·ADP·V_i and S1·ADP·BeF_x complexes. It is suggested that S1·ADP·V_i and S1·ADP·BeF_x complexes represent structural analogues of different transition states of the ATPase cycle, namely the intermediate states S1^**·ADP·P_i and S1^*·ATP, respectively. It is also proposed that during formation of the S1·ADP·V_i complex the region containing both Cys-707 and Lys-83 plays an important role in the spread of conformational changes from the active site of subfragment 1 ATPase throughout the structure of the entire subfragment 1 molecule. In such a case, the effects of reductive methylation of lysine residues on the subfragment 1 structure in the S1·ADP·V_i complex are related to the modification of Lys-83.     

The human force:velocity relationship; activity in the knee flexor and extensor muscles before and after eccentric practice

The human voluntary force:velocity relationship frequently fails to demonstrate the expected high eccentric forces. Possible explanations include unique activation strategies which might be affected by neural learning mechanisms. We investigated the effect of practicing eccentric contractions on (1) the force: velocity relationship of the human knee extensor muscles and (2) the extent of agonist and antagonist muscle activity. Eight healthy adults [seven women, group mean age 31 (SEM 5) years ± ] practised twice a week for 4 weeks using their non-dominant legs. Each session comprised three isokinetic concentric and eccentric maximal voluntary contractions (MVC) at randomised angular velocities of 100, 200 and 300° · s⁻¹. Before and after, the force:velocity relationship was determined bilaterally (angular velocities 0–300° · s⁻¹). There were no significant differences in the forces generated or relative electromyogram (EMG) activity after practice, although there was a trend for dynamic forces to increase. Beforehand, the bilateral eccentric MVC forces were lower than isometric (P < 0.0025); afterwards they were broadly similar. The agonist EMG was similar during isometric and eccentric contractions, but lower during concentric (P < 0.03). Antagonist EMG activity showed considerable individual variation, was similar during all contraction types and tended to be greater during dynamic contractions. These data indicate that neither central learning mechanisms nor total muscle activation strategies underlie the human failure to produce the expected high eccentric voluntary forces in humans. Accepted: 19 September 2000