Relative ages problems

A report from the Mayo Clinic has described 27 elderly patients (mean age 71 years) with aortic stenosis in whom dobutamine stress hemodynamic testing was used to assess the severity of the stenosis (12). There were no severe adverse effects, but relatively minor problems occurred in 16 patients, including chest pain and ventricular extra beats (n = 9 each) and atrial dysrhythmias (n — 4). The authors concluded that the procedure appears to be safe in these high-risk patients, although its diagnostic value may be limited. 

Proper design of biomaterials, especially for long-term applications, should consider mechanical degradation and environmental aging problems. Thermal degradation is of lesser importance in biomaterials, due to the relatively small fluctuations of the temperature in most biomedical applications. 

Pernicious anemia, a deficiency of intrinsic factor, is a relatively common problem caused by malabsorption of dietary cobalamin. It may result from an inherited defect that leads to a decreased ability of gastric parietal cells to synthesize intrinsic factor or from partial resection of the stomach or of the ileum. Production of intrinsic factor often declines with age and may be low in elderly individuals. An alternative circumstance that leads to the development of a B12 deficiency is pancreatic insufficiency or a high intestinal pH, which would result from too little acid being produced by the stomach. Both of these conditions prevent the degradation of the R-binder-B12 complex as a result, B12 will not be released from the R-binder protein and, therefore, cannot bind to intrinsic factor. 

Our approach to this problem has been to try to isolate particular kinds of information that could be used to determine which individual deposited scent most recently or on top compared to the scents of another individual. We have tested three potential sources of information the relative age of scent marks, the spatial configuration of scent marks, and the region of overlap of scent marks. Our strategy has been to determine if a particular kind of cue, by itself, is sufficient to result in selective memory for one of two scents. Each of these possible types of cues will be explained below, along with the logic of our experimental design and the results of our experiments (see Johnston Bhorade, 1998, for more detail). 

Gastric acid and pepsin have a role in vitamin B nutrition, serving to release the vitamin from protein binding and so make it available. Atrophic gastritis is a relatively common problem of advancing age in the early stages there is failure of acid secretion but more or less normal secretion of intrinsic factor. This can result in vitamin B depletion as a result of failure to release the vitamin from dietary proteins, but the absorption of a test dose of free vitamin B is normal. In the stomach, vitamin B binds to cobalophilin, a binding protein secreted in the saliva. 

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