Effects of lemongrass oil on the morphological characteristics and peptidoglycan synthesis of Escherichia coli cells.

The antibacterial effect of lemongrass oil, obtained from the aerial part of Cymbopogon citratus, on cells of Escherichia coli was investigated by electron microscopy and by measuring cell wall formation. Two strains of E. coli K-12 were used, one of which required diaminopimelic acid in the growth medium for its murein formation. Lemongrass oil was found to elicit morphological changes like filamentation, inhibition of septum formation, spheroplast formation, production of 'blisters', 'bulges' or mesosomes, as well as lysis and development of abnormally shaped cells. The incorporation of radioactively labelled diaminopimelic acid into the cell wall murein of strain W7, was inhibited by lemongrass oil in a dose dependent way. The sequence of changes induced by lemongrass oil on bacterial cell morphology and also its interference with murein synthesis in E. coli cells were interpreted to involve the penicillin binding proteins PBP 2 and PBP 3.

Changes in certain iron metabolism variables after a single blood donation.

Signs of iron deficiency have been studied after the first blood donation in 11 healthy men. Six were given 100 mg iron daily, and five received placebo tablets. The total iron-binding capacity and iron absoprtion remained raised for more than 26 days, but had almost returned to the initial values after 70 days. A significant decrease in the stainable bone marrow iron could be shown in all subjects after 26 days; later some restitution was seen in subjects given iron supplements, but not in those given placebo. As the restitution times are long, the interval after blood donation must be taken into account when judging iron metabolism variables in active donors.

[Iron supplement to blood donors. II. Effect of continuous iron supply].

Seventeen conscripts gave blood every second month, the amount representing an average iron loss of 3.5 mg daily. Seven of them were given 20 mg and ten 100 mg iron as ferrous carbonate once daily throughout the study. Before the first and after the fourth and sixth blood donations they were examined with regard to packed red cell volume, serum iron, total iron-binding capacity and stainable bone marrow iron, and a diagnostic iron absoprtion test was performed. Ten conscripts receiving no iron and giving no blood but comparable to those in the test groups with regard to age, exercise and diet served as controls. The stainable bone marrow iron was found to become stabilized at a level with reduced but still perceptible amounts when 20 mg iron was given, and at a level with somewhat greater amounts when the daily dose was 100 mg. Both levels were lower than before blood donation in most subjects, and the negative iron balance was also reflected in the diagnostic iron absorption test. When a healthy person loses 3.5 mg iron daily, supplementation with a 100 mg tablet per day is therefore insufficient to maintain the iron stores at their previous level. The decrease in storage iron is not progressive, however. When the storage iron is reduced, iron absorption seems to be stimulated sufficiently to establish a balance at a reduced storage iron level.