Role of inertia in the measurement of dynamic compliance

Dynamic compliance (Cdyn) was measured at different frequencies (breaths/min) in 30 nonsmoking males and females aged 30-59 yr. In those aged 30-49 yr Cydn at 90 breaths/min was significantly higher than at 15 breaths/min while those aged 50-59 yr showed no significant difference. Assuming an inertance of 0.01 cmH2O/l per s-2, and a sinusoidal breathing frequency, Cydn at 60 and 90 breaths/min was corrected for inertia. In the 30-49 yr age group corrected Cydn did not change with increasing frequency of breathing whereas in the 50-59 yr age group Cydn at 15 breaths/min was significantly higher than at 90 breaths/min (P is less than 0.05). In this age group, four of eight subjects were frequency dependent when corrected for inertia. These findings indicate that inertia influences Cydn at breathing frequencies of 60 per min and above. Unless this is taken into account, frequency dependence of compliance may be missed. The results also indicate that frequency dependence of compliance is normal in some older individuals but is not normal in the younger age group.

On the Mechanism of Quenching by Amines: A New Method for Investigation of Interactions with Triplet States

Rate constants for the quenching of singlet oxygen by a series of substituted N,N-dimethylanilines were obtained by a direct method employing a dye-laser. The Hammett ρ value obtained from the data (−1.71) suggests that a (partial) charge-transfer complex may be responsible for the quenching action. This rate data was combined with that obtained for the total quenching action on the sensitized photooxidation of 1,3-diphenylfuran. The quenching action on the photooxidation reaction is due to both the quenching of singlet oxygen and the quenching of the triplet state of the sensitizer (rose bengal or methylene blue). The combination of the data from each series of experiments resulted in rate constants of quenching of the triplet states of the sensitizers. A number of the N,N-dimethylanilines quenched the triplet states at the diffusion limit. Hammett ρ values (−1.86 for rose bengal and −4.19 for methylene blue) indicate that charge-transfer intermediates are probably responsible for the quenching action. This was confirmed by the observation of a transient intermediate assigned to the charge-transfer radical of methylene blue. The technique used here represents a novel approach to the investigation of triplet states.

Infective endocarditis in drug addicts. Experiences with medical and surgical treatment

Isolated tricuspid valvular endocarditis is no longer rare, and its increasing incidence has paralleled the rise in heroin addiction. In the period between December, 1969 and December, 1971, 16 episodes of bacterial endocarditis occurred in 13 individual drug abusers at the Ben Taub General Hospital, Houston. The tricuspid valve (TV) was involved in all cases. Two patients required surgery during the acute infection; one underwent total excision of the TV without replacement, and one received aortic and TV prostheses because of progressive heart failure. Antibiotic therapy was individualized and guided by tube dilution sensitivities and serum bactericidal levels. In view of the excellent response to antibiotic therapy, surgery for infected prosthetic or natural valves is presently reserved for those patients with progressive cardiac failure or infections unresponsive to medical therapy.

Mid-life Crisis: Growth or Stagnation

Mid-life has developmental stages and particular tasks that must be successfully completed for growth to continue and psychological stagnation to be avoided. Characteristic of different phases of mid-life are three stages of ego mastery: alloplastic mastery is associated with early adulthood, autoplastic mastery is associated with maturity, and omniplastic mastery is found in old age. A special perspective on one's life and a need to examine one's life are found in mid-life. Difficulties can occur in dealing with this phase and the family physician can be of significant help to his patients who are working through the mid-life crisis.

A selective method for the enrichment of cytoplasmic markers in Saccharomyces cereviaiae

Sensitive diploids of Saccharomyces cerevisiae were used to select for resistance to oligomycin and erythromycin when glycerol was used as the energy source. Genetic analyses revealed that 10 erythromycin and 4 oligomycin mutants were cytoplasmically inherited.