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Acurate knowledge of essential nutrients is a sine qua non of good nutrition. Such information is needed for the prevention and repair of dietary deficiencies arising from food shortages and also in situations where the capacity to handle food is limited by disease states. Evaluation of the requirements for essential amino acids has been peculiarly difficult, since this involves the construction of a diet in which the quantity of a single amino acid can be varied at will. The problem has been approached in several ways:Use has been made of natural proteins deficient in one or another amino acid. This method has very limited applicability, for nature has been singularly unobliging in providing a variety of such proteins.Chemically degraded proteins or protein hydrolysates have been used. A number of procedures can be used to destroy one or more amino acids, which can then be replaced in

Extract: The changes in plasma aminogram produced by variations in level of protein intake provided either as whole protein or a mixture of amino acids were studied. Controls were 29 normal infants, one to three months of age, fed a standard evaporated milk formula providing 3 to 3.5 g/kg/day of protein (fig. 1 and table II). Results obtained with the lowest protein intake (1.1 g/kg/day) are illustrated in figure 2 and presented in table III. Alterations in the plasma aminogram are noted as early as two days after the reduction in intake and become more pronounced as the feeding is prolonged. The most striking changes are depression of the branched chain amino acids (leucine, isoleucine and valine) and of lysine and tyrosine. Glycine and serine are elevated with glycine showing the greater elevation. Less striking changes are decreased concentrations of threonine, phenylalanine, ornithine, butyrine, cystine and proline.The aminograms obtained with feedings of 1.3 and 1.5 g/kg/day are very similar to those obtained with the more extreme degree of protein reduction (fig. 3 and table IV). The aminogram after feeding 1.7 g/kg/day remains within the range of average ±1 standard deviation except for the elevation of glycine.A high intake of milk protein, 9 g/kg/day, results in an increase in the levels of a majority of the amino acids (fig. 5 and table V). The sole exception is glycine, which tends to be low. Marked increases occur in the branched chain amino acids, valine being the most affected; there is also a large increase in the level of proline. The greatest elevations occur in the levels of methionine, which also show the most marked individual variation, elevations ranging from 2 to 35 times normal average value. An apparent tendency of the methionine level to return towards normal with prolonged feeding of the high protein diet is evident on the graph. The significance of this finding must be questioned, however, since the subjects who were maintained the longest on this diet were those who originally did not have the very high levels of methionine.There are some differences in the aminogram when infants are fed the equivalent of 3.5 g/kg/day in the form of amino acids instead of intact protein (fig. 6 and table VI). On the amino acid diets, lower average plasma values are seen for the branched chain amino acids, alanine, proline, asparagine and citrulline; higher values are observed for threonine and serine. The markedly elevated levels of plasma amino acid observed after feeding 9 g/kg/day of whole protein are not seen after feeding the equivalent amount of nitrogen as an amino acid mixture (fig. 7 and table VII). There is elevation only of valine and serine. When individual subjects were shifted from the high protein to the high amino acid diet, the pattern shifted within 24 hours.Speculation: A more precise and sensitive indicator of the state of protein nutrition is needed. While the level of the plasma amino acids changes rapidly with alterations in protein intake, much more work is necessary before it can be used to evaluate protein adequacy.

A synthetic diet which provides nitrogen as a mixture of eighteen l-amino acids was used to determine the methionine requirement of seven healthy infants. It ranged between 32 and 49 mg. per kg. day. Withdrawal of methionine from the diet resulted in marked changes in the plasma aminogram. These included a rise in the threonine, serine, proline, tyrosine and phenylalanine levels as well as a fall in the plasma methionine level. A decrease in the plasma cholesterol level was often associated with a suboptimal intake of methionine.

Analyses of the free amino acid content of the plasma and erythrocytes were carried out in two groups of premature infants who were given 2 and 9 g protein/kg per day. Both groups gained weight normally and were in good health. There was a depression of the plasma lysine level and an elevation of the glycine level on the low protein diet. On the high protein diet there was an increase in the levels of proline, tyrosine, phenylalanine, methionine, and the branched-chain amino acids (leucine, isoleucine, and valine). However, the glycine level was depressed. The red blood cell content of amino acids paralleled the plasma so that red blood cell plasma ratio tended to remain constant regardless of the variation in protein intake.

In studies designed to evaluate the threonine requirement of normal infants a synthetic diet was employed which provided nitrogen in the form of a mixture of 18 essential and non-essential amino acids, all as the natural L-isomers. It was found that infants would gain weight normally and exhibit every sign of health on such a diet, although a somewhat higher than average caloric intake was at times required.

A study to evaluate the phenylalanine requirement of infants was carried out employing a synthetic diet, the nitrogen moiety of which consisted of a mixture of 18 amino acids, essential and non-essential, all as the natural L-isomers. By graded reduction of the phenylalanine, which was replaced by glycine, the minimal phenylalanine intake compatible with normal health was determined. It was found to be approximately 90 mg per kilogram per day.

Describes an experience during a trip to Chatham Islands in New Zealand. Description of the trip to Owenga, on the south east corner of the island; Challenges faced during the trip; Activities on the southwest shore of Te Whana Lagoon.

The article features Rick Osborne, a Wellington farm forester. In the late 1960s, he decided he wanted to grow trees and bought land at the Sounds. He began planting on 260 hectares in 1973, leaving 40 hectares for cattle and sheep. In 1975, he acquired land in Marlborough of which most are in forestry. In 1987, Rick bought a sawmill which is now known as the Flight Timbers Ltd., which produces 30 cubic meters of timber a day. He forged a partnership with Jacob Mannothra, forming Zindia Ltd., which exports logs to India.

Relates a trip to the Chatham Islands, New Zealand in October 2003. Information on the Chatham Islands Enterprise Trust; Growth of wind sensitive plants in Admiral Gardens, a rambling area sheltered by different trees; Details of the visit to Port Hutt, a settlement and a wet fish processing plant owned by Kevin Clark.

The article features the Wellington Branch of the New Zealand Farm Forestry Association. A brief description of the varied topography, soils and climate of the Wellington region is given. Topics discussed include an assessment of the committee in terms of the number of its members and their forest resource, the key characteristic of the council is its absentee owners and the results of a survey done to collect information about areas and species, and to know who the council is trying to service with branch activities.