Flow microfluorometry study of diauxic batch growth of Saccharomyces cerevisiae

Flow microfluorometry reveals complex changes in types and relative numbers of different Saccharomyces cerevisiae cell forms during glucose-limited diauxic batch growth.

Applications of purification reactions for minimizing reaction-generated enzyme poisoning

A mathematical model has been employed to examine the interplay of reaction and mass transfer in immobilized enzyme systems involving reaction-generated enzyme poisions. Deactivation rates can be significantly reduced in some cases by catalyzing a purification reaction in which the poison is transformed into an innocuous substance. This conclusion in illustrated experimentally for reaction-generated H2O2 in a continuous-flow stirred slurry reactor containing glucose oxidase immobilized on activated carbon.

Characterization of bacterial growth by means of flow microfluorometry

By means of flow microfluorometry, the protein and nucleic acid contents of individual bacterial cells may be measured at the rate of several thousand cells per second. Accumulation of such information over a few minutes yields the composition distribution of the microbial population. These distributions have been determined at different times during batch growth of Bactillus subtilis, and the results indicate that the variance of cell composition decreases as the population passes through the exponential into the stationary phase. The relative abundance of endospores and vegetative cells as well as the protein distributions of these subpopulations may be readily determined from flow microfluorometry data. Experimental access to such details of microbial population dynamics should foster improved understanding of cell growth, spore germination, and spore formation kinetics.

The cultivation of the rumen ciliate Entodinium bursa in the presence of Entodinium caudatum

The rumen ciliate protozoon Entodinium bursa has been grown in vitro in the presence of bacteria and Entodinium caudatum for over a year at population densities of 100 to 200 ml-1. The medium contained potassium phosphate, prepared fresh rumen fluid, cysteine, wholemeal flour (or rice starch), dried grass and a culture of the spineless form of Entodinium caudatum. Entodinium bursa has an obligate requirement for this protozoon and died within 48 h in its absence. During growth from a 2% inoculum, the mean generation time of E. bursa was 6 h. Entodinium bursa engulfed 1-5 to 2-5 E. caudatum organisms h-1, and when E. caudatum was in excess it developed caudal spines for the first time in 17 years; these spined forms were engulfed much less readily than the spineless organisms.

The cultivation of cellulolytic protozoa isolated from the rumen

Conditions are described for the isolation from the rumen and subsequent growth of six species of cellulolytic protozoa: Enoploplastron triloricatum, Eudiplodinium maggii, Diploplastron affine, Epidinium ecaudatum caudatum, Diploidinium monacanthum and Diploidinium pentacanthum. The protozoa were grown in an atmosphere of 95% nitrogen plus 5% carbon dioxide, or pure carbon dioxide, in a potassium phosphate-rich medium containing cysteine, sometimes 10% prepared fresh rumen fluid, and daily additions of powdered dried grass. Population densities of 10 to 6000 protozoa/ml (depending on the species) were obtained in cultures that were diluted with fresh medium twice each week. Extracts of these protozoa digested a [14C]cellulose preparation, liberating soluble 14C-labelled compounds.

A double-blind comparison of lithium carbonate and maprotiline in the prophylaxis of the affective disorders

A double-blind prospective study was carried out comparing the prophylactic effect of maprotiline and lithium carbonate over a period of one year in patients suffering from recurrent affective disorders. The average Affective Morbidity Index was lower, but not significantly so, in patients treated with lithium. A further analysis, based on dividing patients into those with no affective morbidity and those who showed some affective morbidity during the study, demonstrated lithium carbonate to be significantly superior to maprotiline both in the group as a whole and in unipolar depressives. A correlation between high plasma maprotiline concentration and low morbidity was observed and was in line with an earlier report. A highly significant negative correlation (r=-0-97; p less than 0-001) was found between plasma maprotiline concentration and body weight. Although the results showed lithium carbonate to be superior to maprotiline in the study, it should be emphasized that the plasma levels of lithium were constantly monitored and maintained at what is considered to be its optimum concentration, whereas the maprotiline treated patients were kept on a fixed dosage regime irrespective of plasma levels.

Effects of physical activity on weight reduction in obese middle-aged women

Increased physical activity consisting of jog-walking 2.5 miles and 1 hr of calisthenics/week was the primary focus of a 17-week weight reduction program in 22 obese (X = 40% body fat) women ages 30 to 52, many of whom had failed at previous attempts to lose weight by dieting alone. Regular exercise was also increased substantially on an individual basis. Caloric restriction was self-determined and was generally moderate, accounting for about 60% of the total mean energy deficit. Initial and final evaluations included body composition by hydrostatic weighing, progressive multistage exercise testing, and plasma lipid and lipoprotein analyses. A mean relative body fat reduction of 5% (P less than or equal to 0.001) was achieved by a drop in fat body weight (X = 5.4 kg; P less than or equal to 0.001) which closely paralleled that of total body weight (X = 4.2 kg; P less than or equal to 0.001). Mean heart rates and systolic blood pressures at identical submaximal exercise intensities were significantly lower at the time of reevaluation. Mean plasma triglyceride and total cholesterol concentrations did not change significantly (P greater than 0.05). However, the high-density lipoprotein cholesterol/low-density lipoprotein cholesterol ratio increased significantly (P less than or equal to 0.05). Increased physical activity combined with moderate dieting is a feasible approach to weight reduction in middle-aged women.

Plasma tryptophan and sheep

Free, bound, and total plasma tryptophan (F.P.T., B.P.T., and T.P.T.) levels have been measured throughout the night in six young female volunteers. All-night polygraphic sleep recordings were also made. No direct temporal relationship was found between plasma tryptophan levels and specific sleep stages. The mean F.P.T. levels, however, were found to have a positive correlation with rapid-eye-movement (R.E.M.) sleep and a negative correlation with non-R.E.M. sleep. An inverse relationship existed between the F.P.T. and B.P.T. levels. There appeared to be a diurnal variation in F.P.T. levels, with high readings in the first half of the night.

Membrane transport against the external driving force due to mass transfer-reaction coupling

Coupling between chemical reactions and transport phenomena can cause the substrate concentration at the surface of a membrane to be lower on the substrate-rich side than the substrate-lean side. Thus, the diffusing flux inside the membrane may be counter to the overall external concentration driving force. Graphical solutions of various steady states of such membranes are presented.