Transient inhibition of DNA synthesis has been used as an experimental technique in a number of situations. Massive doses of methotrexate, a folic acid antagonist, have been used to inhibit humoral (Berenbaum & Brown, 1965) and cellular immune responses (Berry, 1969) and to delay the appearance of vertebral ossification centres (Berry, 1971). More recently its effects on the expression of a pol...

Lung cancer is one of the most common malignancies and is the leading cause of cancer-related death worldwide (Jemal et al., 2010). Although epidemiologic studies have proved multiple risk factors such as age, gender, smoking, environmental pollution related to the occurrence of lung cancer, there are significant variations between individuals when exposed to same risk factors, for instance cig...

CONTEXT High plasmatic homocysteine levels have been associated with arterial and venous thrombosis. The C677T methylene tetrahydrofolate reductase (MTHFR) gene mutation is one of the known causes for high homocysteine levels in plasma. Anticardiolipin antibody (ACA) is also associated with thrombosis and, along with other clinical complications such as recurrent abortion and stillbirth, is par...

BACKGROUND Rates of renal and cardiovascular disease are high among Aboriginal Australians living in remote communities. Nutritional problems, in particular low folate levels, are also common. This suggests that increased homocysteine concentrations might be widespread, and a possible contributor to the high rates of cardiovascular disease. AIMS To examine homocysteine concentrations, and the...

The first step in the conversion of folate to the functional form of the vitamin is its reduction to a tetrahydro derivative (1). The enzyme, folate reductase (also called dihydrofolate reductase or tetrahydrofolate dehydrogenase), which catalyzes this reaction has been partially purified from a variety of tissues in different laboratories (2-8). Aminopterin and amethopterin are potent inhibito...

The transient state kinetics of catalysis for dihydrofolate reductase (DHFR) from several enzyme sources including highly purified recombinant human enzyme (rHDHFR) have been examined. Like DHFR from Escherichia coli, the enzyme from Lactobacillus casei, and isoenzyme 2 from Streptococcus faecium exhibit a slow increase in activity upon addition of substrates to enzyme. No slow hysteresis of th...

The early studies of Fountain et al. (I) demonstrated clearly that injected amethopterin’ persists in certain mouse tissues such as liver and kidney for periods up to 8 months. The suggestion was made by these authors and by others (2,3) that this retention was due to binding of the drug to an enzyme, perhaps one involved in the conversion of folate to tetrahydrofolate. Such prolonged retention...

In methylotrophic bacteria, formaldehyde is an important but potentially toxic metabolic intermediate that can be assimilated into biomass or oxidized to yield energy. Previously reported was the purification of an NAD(P)(+)-dependent formaldehyde dehydrogenase (FDH) from the obligate methane-oxidizing methylotroph Methylococcus capsulatus (Bath), presumably important in formaldehyde oxidation,...

BACKGROUND AND PURPOSE Elevated plasma levels of homocysteine are associated with an increased risk of deep-vein thrombosis. Through a case-control study, we examined the potential association among homocysteine, folate and vitamin B12 levels, and the common C677-->T mutation in the methylene tetrahydrofolate reductase (MTHFR) gene in patients with cerebral venous thrombosis (CVT). METHODS Fo...