Too much of a good thing

Here is a case in which too much of a good thing is not a good thing. Excess vitamin A is toxic, particularly to the liver. The UL is 3 mg/day for adult men and women, only three or four times greater than the RDIs. Most health food stores sell P-carotene supplements. Unless you have reason to believe that you are at risk of vitamin A deficiency, there is no reason to use these supplements. 

However, here, too much of a good thing is not so hot. If retinoic acid is administered systemically during embryo formation (in experimental animals to be sure), severe malformations result in the offspring. Thus, retinoic acid is a teratogen. 

The amount of acetylcholine present in the synapse and the amount of time that it remains there are critical. For example, the venom of the black widow spider is highly neurotoxic. It contains a protein known as a-latrotoxin that elicits the release of massive amounts of acetylcholine at the neuromuscular junction. Too much of a good thing can be a serious problem. 

The literal interpretation of a societal approach instructs health care decision makers to pay attention to the effect of current reimbursement policies on the development of new products. Too high a price, and there is too much of a good thing - too many beneficial new products. Too low a price, and the bonanza may dry up, with harm to health, to investment, and to employment. 

Although a small amount of strong acid catalyst is essential in the preparation of esters from acids and alcohols, the amount of acid catalyst added must not be too large. The reason for the too much of a good thing behavior of the catalyst can be understood from the basic properties of alcohols (Section 15-4B). If too much acid is present, then too much of the alcohol is converted to the oxonium salt ... 

Although arousal is usually considered to be a state of increased dopamine and norepinephrine and inattentiveness is considered to reflect deficiencies in these neurotransmitters in these pathways, this is only somewhat true even in persons without a cognitive disorder. Thus, more of these neurotransmitters will enhance attention, but only to a certain extent. Too much of a good thing, like dopamine or norepinephrine, will actually lead to deterioration in cognitive performance. Thus, hyperarousal is more likely to be associated with inability to concentrate than with heightened attention span. 

Stahl, S.M. (1997) Serotonin it s possible to have too much of a good thing. Journal of Clinical Psychiatry 58(12), 520-1. 

Synthesis is regulated at several other places as well. After IMP is made the pathway splits to build either AMP or GMP. Enzyme XII, which catalyzes the first step from IMP to AMP, is itself slowed down by excess amounts of AMP. Similarly, the catalysis of the first step from IMP to GMP is inhibited by excess GMP. (Unlike King Midas, the enzymes can tell when they have too much of a good thing.) Finally, Enzyme XII uses GTP as an energy pellet because, if a lot of GTP is around, more A nucleotides (AMR, ADP and ATP) are needed to keep the supply in balance. The final step in the synthesis of GMP uses ATP as an energy source for similar reasons. ... 

D Elia, C. F. (1987). Nutrient enrichment of the Chesapeake Bay Too much of a good thing. 

Too much of a good thing. A simple Michaelis-Menten enzyme, in the absence of any inhibitor, displayed the following kinetic behavior. The expected value of shown on the> -axis. 

Use temperature for disease control. You can control certain diseases by exposing plants or soil to high or low temperatures. In many cases, though, too much of a good thing can be fatal, so be sure you know the pros and cons of each method before treating your whole crop. 

The more the merrier. A contrasting mechanism is one can have too much of a good thing. I return to this pair, too, in 1.8. 

Maggie s case is very unusual in that after becoming well she developed a sore throat. I don t know what the explanation is—maybe too much of a good thing. Fortunately, this paradoxical reaction is uncommon. This should not be confused with the die-off phenomenon (Herxheimer reaction) or the Herring phenomenon. (But let s not get into that.)... 

Fawcett, J. W., Growth cone collapse too much of a good thing , Trends Neurosci., 16, 165, 1993. 

J Barber and B Andersson (1992) Too much of a good thing light can be good and bad for photosynthesis. Trends Biochem Sci 17 61-66... 

It can be quite correctly argued that life exists on Earth because of the abundant liquid water. Other planets have water, but they either have it as a gas (Venus) or ice (Mars). Recent studies of mars reveal the presence sometime in the past of running fluid, possibly water. The chemieal nature of water is thus one we must examine as it permeates living systems water is a universal solvent, and can be too much of a good thing for some cells to deal with. 

Fluorine, like iodine, in minute amount is essential to the human body it enables the teeth to develop a hard enamel and resist decay. But this is a case in which it is easy to have too much of a good thing. In 1934 the children at Malden in Essex were found to be suffering from mottled teeth — a name that explains itself. This was traced to the presence of excess fluorine ions in the water to the extent of 4 5 to 5 ppm. Small quantities up to about 1 ppm appear to be beneficial. 

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