The respiratory burst of human neutrophils treated with various stimulators in vitro is dampened by exogenous unsaturated fatty acids

Cis-unsaturated free fatty acids (FFA) at concentrations between 10 and 30 microM suppressed the superoxide respiratory burst induced in human neutrophils by the chemotactic peptide, N-formylmethionyl-leucyl-phenylalanine (FMLP). Corresponding trans-isomers had a reduced efficacy while saturated FFA were inert. The effects of unsaturated FFA were maximally achieved after several min of preincubation with cells and reversed upon washing. Increased concentrations of Ca2+ in the medium also relieved the inhibition. Unsaturated FFA were equally effective in dampening the respiratory burst induced by fluoride ions but less so with bursts elicited by 9 nM phorbol myristate acetate (PMA). Moreover reactions triggered by higher concentrations (e.g., 100 nM) of PMA were resistant to the effects of FFA. Radioimmunoassays showed that unsaturated FFA directly elevated intracellular cyclic adenosine monophosphate (cAMP) by severalfold above basal levels. It is suggested that inhibition is brought about by unsaturated FFA perturbation of the neutrophil membrane structure, perhaps with an independent contribution from a cAMP-dependent mechanism.     

Fluorescent inhibitors of a cell surface protease used to locate leukaemia cells in kidney sections

Guanidinobenzoatase is a trypsin-like protease on the surface of cells capable of migration, for example leukaemia cells. We have used a number of fluorescent probes that are competitive inhibitors of guanidinobenzoatase to locate leukaemia cells in resin sections of kidney tissue obtained from leukaemic rats. We have demonstrated how this competitive inhibition system can be used to direct desired molecules (such as cytotoxic drugs) to these cells and to monitor the arrival of such compounds at the active site of guanidinobenzoatase. The principles developed in this study could equally well be applied to other enzymes on other cells provided suitable competitive inhibitors were designed. The presence of an enzyme on the surface of a cell can be used to direct molecules to that cell provided that these molecules contain a functional group that acts as an inhibitor for the chosen enzyme.     

Ammonium release by zooplankton in suspensions of heat-killed algae and an evaluation of the flow-cell method

The maximum excretion rate of NH₄ (39 nmol mg dry wt^–1h^–1) was directly measured for Daphnia pulex by measuringNH₄ accumulation in bottles containing D. pulex and dense, satiatingsuspensions of heat-killed algae. Ammonium release rates inthe algal suspensions were compared to those of individual animalsremoved from the suspension and placed in flow cells. Ammoniumrelease rate, R (nmol mg dry wt^–1 h^–1). in the flowcell decreased very rapidly with time, t (min), after removalaccording to the relation R = 26 + 25e^–0.16t. Ammoniumexcretion obtained by the flow cell method after extrapolationto time zero was not significantly different from that obtainedin the bottles. The considerable experiment-to-experiment variationin NH₄ excretion was in large part correlated (r² = 0.73) withthe feeding rate on the algae.     

DETERMINATION BY NEUTRON ACTIVATION OF COPPER, MANGANESE, AND ZINC IN THE PINEAL BODY AND OTHER AREAS OF BRAIN TISSUE

Abstract— Neutron activation analysis was used for the simultaneous determination of copper, manganese and zinc in the brains of calves, cows and pigs. Measurements of these three elements in as many as 11 different regions of the brain showed that the highest content is always found in the pineal body. Typical values for calf brains are: Cu, ∼20 μg/g; Mn, ∼3 μg/g; and Zn, ∼90 μg/g dry pineal tissue. As a first approximation, the ratio of Cu:Mn:Zn is roughly constant for all regions.     

Nature of Escherichia coli B(P1) Yielder Cells at the Time of Infection with Restricted T1

In the infection of Escherichia coli B(P1) with restricted T1, it was shown that yielder cells consist of both special and nonspecial cells. Special or predetermined yielders occurred only among the earliest yielders. In most instances, yielder-cell formation was most easily explained by assuming that the first step was a chance escape of the restricted phage DNA from the degrading enzyme of the restricting cell.     

Cardiac Monitoring in a Community Hospital—Analysis of 18 Months' Experience

Cardiac monitoring facilities have been present in teaching hospital centers for over five years. A substantial decrease in mortality has been observed in monitored patients with acute myocardial infarction. The community hospital system offers a challenge to effective monitoring since many physicians care for patients and often many kinds of therapy are used.After 18 months of operation mortality from myocardial infarction was only 16.6 percent in a community hospital monitoring unit where the majority of the emergency care and resuscitation was carried out by nurses. Vital to this success was the use of standing orders for nurses, requirement of privilege to practice within the monitoring facility and acceptance of the nurse as a therapist in emergency situations.Fourteen patients were successfully resuscitated and were later discharged from the hospital. Four of them had ventricular fibrillation from digitalis intoxication.Patients with shock and severe congestive heart failure continue to be a major unsolved clinical problem. The results indicate that the potentially viable patient with serious electrical disturbances can almost invariably be salvaged.