Isolation of cell wall mutants in Aspergillus nidulans by screening for hypersensitivity to Calcofluor White

As a first step toward identifying novel genes of wall metabolism in filamentous fungi, we have screened a collection of Aspergillus nidulans mutants for strains exhibiting hypersensitivity toward the chitin binding agent Calcofluor White (CFW). This strategy has been used previously to identify cell wall mutants in Saccharomyces cerevisiae. We have identified 10 mutants representing eight loci, designated calA through calH, for Calcofluor hypersensitivity. All cal mutants are impaired for sporulation at 30 C or 42 C or both, and in eight of the 10 mutations this sporulation defect shows at least partial osmotic remediability. All cal mutants show elevated sensitivity to one or more of the following agents: Caspofungin, Nikkomycin, Tunicamycin, Congo red and SDS, which are recognized wall-compromising agents or have been shown to be inhibitory to wall integrity mutants in yeast. Seven of the 10 cal mutants show swelling at elevated temperature, which in most cases is osmotically remediable. Spore swelling also can be induced at 30 C in all but one of the cal mutants by germination in the presence of one or more of the following: Caspofungin, Nikkomycin or Tunicamycin. Analysis of wall sugars showed no major changes in mutant strains. We also report that the chitin synthase inhibitor Nikkomycin induces excessive spore swelling during germination in all tested strains that have wild type cell wall metabolism (GR5, A4, A28 and AH12) at 42 C but not at 30 C. This effect mimics that of certain temperature-sensitive swollen cell (swo) mutations.

Covert speech behavior during a silent language recitation task

This study tested the prediction that covert speech behavior measured electromyographically from the lips is significantly more prominent during a brief silent-language recitation task than a brief nonlanguage visualization task. Subjects were 20 right-handed, adult volunteers who agreed to participate. Subjects were tested in a multiple-baseline reversal design following an ABAB procedure whereby A1 and A2 were 30-sec. rest periods. B1 and B2 were alternatively assigned 30-sec. silent-language recitation and visualization test periods, respectively. Subjects' dorsal lips and nondominant forearm EMG measures were taken during resting baseline and testing conditions. In addition, subjects' skin surface temperature and heartrate were measured during the rest and test conditions. For the silent-language task, subjects were asked to recite 'mentally' the Pledge of Allegiance to the flag. Subjects were instructed to 'imagine seeing' the American flag for the visualization task. Subjects' mean lip EMG activity increased significantly from rest to the silent-language recitation task, while no significant change in mean lip EMG was observed from rest to the visualization condition.

Effects of membrane stabilization on the safety of hypothermic arrest after aortic cross-clamping

Twenty dogs underwent 1 hour of topical hypothermic arrest; five were untreated, five received methyl prednisolone (30 mg/kg), five received 0.2% procaine, and five received both drugs. Arrest was almost immediate (less than 2 min) with procaine, but was delayed 14 +/- 3 minutes in the other groups. Steroid-treated dogs had the highest post-ischemic left ventricular (LV) blood flows (110 +/- 22 cc/100 g/min) (P less than 0.05). Membrane-stabilizing drugs did not prevent myocardial edema; LV water rose 2% (P less than 0.01) in all groups. Post-ischemic LV compliance was depressed most (55%) in the untreated group, and less after procaine (30%) (P less than 0.05). Postischemic LV performance was depressed 44% (P less than 0.01) in the untreated dogs, and returned to near normal levels with steroid (89% recovery), procaine (97% recovery), and both drugs (95% recovery). We conclude that steroids and/or procaine protect against postischemic myocardial depression but do not prevent myocardial edema. Combining steroids and procaine provide no apparent added benefit, but procaine has the technical advantage of almost immediate cardioplegia.

Studies on myocardial reperfusion injury. I. Favorable modification by adjusting reperfusate pH

This study tests the hypothesis that postischemic myocardial depression can be reduced by providing an initial reperfusate pH which is appropriate for myocardial temperature (i.e., metabolic systems function optimally when pH is kept slightly alkaline to the neutral point, which changes with temperature in concordance with the pK of water). Ten dogs underwent 1 hour of ischemic arrest with topical hypothermia (intramyocardial temperature 16+/-2 degrees C). The initial reperfusate (500 cc of blood from the extracorporeal circuit) was infused (100 cc/minute) into the proximal aorta just before removing the cross-clamp. Reperfusate pH was kept at 7.4 in five dogs (control) and raised to 7.8 with THAM [tris (hydroxymethyl) aminomethane] in five dogs. Measurements 30 minutes after reperfusion showed that raising reperfusate pH to 7.8 resulted in (1) higher subendocardial blood flows (109+/-20 vs 61 cc+/-8 cc/100 gm/minute), (2) redistribution of postischemic blood flow toward the subendocardium (endocardial/epicardial flow 1.25+/-0.1 vs 1.0+/-0.03), (3) higher left ventricular oxygen uptakes (0.046 vs 0.033 cc/100 gm/beat), (4) better postischemic left ventricular compliance (56+/-3% more compliant), and (5) improved left ventricular performance (88+/-7% recovery vs only 57+/-3% recovery at pH 7.4). Postischemic edema (2% water gain) was unchanged by pH modification. We conclude that initial reperfusion with the appropriate pH provides an optimal milieu for restoration of cellular metabolism, counteracts the acidosis of ischemia, and improves postischemic left ventricular blood flow, distribution, oxygen uptake, compliance, and performance.