I onizing radiation fills the universe. Daily ionizing particles and rays collide with molecules in 1% of the 100 trillion cells that make up the average human. These collisions generate clusters of free radicals known as reactive oxygen species that randomly damage cellular constituents including DNA (1). Certain types of ionizing radiation are more effective at generating reactive oxygen spec...

Besides extensive investigations of low dose hypersensitivity after low-LET radiation, more recently similar effects have been also detected after high-LET radiation using low energy He ions [1] or high energy carbon ions [2]. Usually, a cutoff value in colony size is used to distinguish surviving from inactivated cells. However, essential information is lost when using only two categories for ...

A study has been performed on the effect of Norinyl-1 and Ortho-Novin, two low-dose oral contraceptives, on blood-clotting factors. Ortho-Novin contains twice the amount of hormone as Norinyl-1. It was therefore possible to observe whether any changes detected were related to the dose of oestrogen-progestin combination. The women were tested in parallel with matched normal female controls and a...

Previous studies showed that sub-MIC levels of β-lactam antibiotics stimulate biofilm formation in most methicillin-resistant Staphylococcus aureus (MRSA) strains. Here, we investigated this process by measuring the effects of sub-MIC amoxicillin on biofilm formation by the epidemic community-associated MRSA strain USA300. We found that sub-MIC amoxicillin increased the ability of USA300 cells ...

OBJECTIVES We sought to assess the odds of experiencing adverse effects with low dose amiodarone therapy compared with placebo. BACKGROUND An estimate of the likelihood of experiencing amiodarone-related adverse effects with exposure to low daily doses of the drug is lacking in the published reports, and little information is available on adverse effect event rates in control groups not recei...

Evaluations of the health effects of exposures in the workplace and environment have broadened to include effects on reproduction, as well as on the development of cancer. Models to assess risks associated with varying doses of exposure rest almost entirely on data about cancer. In this paper we discuss some distinctive features of reproduction which bear on the interpretation of such models, w...

BACKGROUND Aspirin is commonly used by elderly patients. In previous studies we found transient changes in renal function induced by low doses of aspirin. OBJECTIVES To investigate the mechanisms of these effects. METHODS The study group included 106 long-term care stable geriatric inpatients. Diet and drugs were kept stable. The study lasted 5 weeks; during the first 2 weeks 100 mg aspirin...

-The influence of vitamin A-related compounds on hyperplasia and metaplasia induced by methylcholanthrene was studied in mouse prostate glands in organ culture. Methylcholanthrene was found to cause extensive hyperplasia and squamous metaplasia of the prostatic epithelium which persisted after withdrawal of the carcinogen. The retinoids included retinoic acid and 6 of its structural analogues s...

background and purpose: progressive degeneration of dopaminergic neurons in the midbrain is the main mechanism of parkinson’s disease (pd). although potassium channels affect neural activity and death in this area, little research has investigated the effect of potassium channel blockers, such as 4-aminopyridine in the pretreatment of pd. methods: fifty-six healthy male wistar rats were selecte...