Melissa officinalis (MO, English: lemon balm, Lamiaceae), one of the oldest and still most popular aromatic medicinal plants, is used in phytomedicine for the prevention and treatment of nervous disturbances. The aim of our study was to assess the effect of subchronic (28-fold) administration of a 50% ethanol extract of MO leaves (200 mg/kg, p.o.) compared with rosmarinic acid (RA, 10 mg/kg, p.o.) and huperzine A (HU, 0.5 mg/kg, p.o.) on behavioral and cognitive responses in scopolamine-induced rats. The results were linked with acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), and beta-secretase (BACE-1) mRNA levels and AChE and BuChE activities in the hippocampus and frontal cortex of rats. In our study, MO and HU, but not RA, showed an improvement in long-term memory. The results were in line with mRNA levels, since MO produced a decrease of AChE mRNA level by 52% in the cortex and caused a strong significant inhibition of BACE1 mRNA transcription (64% in the frontal cortex; 50% in the hippocampus). However, the extract produced only an insignificant inhibition of AChE activity in the frontal cortex. The mechanisms of MO action are probably more complicated, since its role as a modulator of beta-secretase activity should be taken into consideration.

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Background: Polymorphisms which are presented below may be the cause of inherited thrombophilia and may result in pregnancy loss. The hypothesis is based on a number of cardiology studies which have confirmed the involvement of these polymorphisms in thrombotic incidents.

Alloxan is a well-known and universally used agent for evoking experimental diabetes through its toxic effect on the B cells of the Langerhans islets. In our study, blood levels of alloxan in children with insulin-dependent diabetes mellitus were investigated. The observations were made in 68 children aged 6-15 years and in a control group of 44 healthy children in the same age range. Alloxan levels were estimated spectrophotometrically. The mean level of alloxan in blood from children with insulin-dependent diabetes mellitus was 8.76 +/- 9.64 micrograms/ml and in blood from healthy children was 1.53 +/- 1.10 micrograms/ml. The difference was statistically significant (P < 0.05). The metabolism of alloxan leads to the production of free superoxide radicals which, as is well known, injure cells and cause conditions conducive to the occurrence of diseases from autoimmunity. The results obtained suggest therefore that higher levels of alloxan in diabetic children are of significance in the onset of insulin-dependent diabetes mellitus.

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