Skeletal challenge: an experimental study of pharmacologically induced changes in bone density in the distal radius, using gamma-ray computed tomography.

Bone density (BD) at the distal end of the radius was measured serially with gamma-ray computed tomography (gamma-CT) in five groups of healthy postmenopausal women. One group comprised untreated controls; women in the other groups were subjected to pharmacologic challenge with putative activators and/or depressors of bone remodeling. The challenge agents, taken orally, were ergocalciferol (vitamin D2) alone and followed by calcium; calcitriol (1,25(OH)2D3), and prednisone. All of the subjects showed changes in BD following challenge; these changes were significant (P less than 0.05) for the groups receiving vitamin D2 and vitamin D2 plus calcium. Responses to ergocalciferol, calcitriol, and prednisone were similar within groups, whereas the group receiving ergocalciferol then calcium comprised two distinct subgroups: bone density transiently increased in one and decreased in the other. For all five groups, the direction of change in bone density in response to the challenge, and its duration and magnitude, were consistent with reported histomorphometric data. We conclude that gamma-CT assessment of change in bone density after pharmacologic challenge provides a useful noninvasive approach to skeletal investigation.

Methods of assessing diabetic control.

Control of diabetes from complete normalisation to less adequate degrees of metabolic regulation needs to be assessed with regard to conditions of evaluation and to severity of the disease. Under optimal conditions the therapeutic events should occur with well-timed regularity. Different assessment criteria are appropriate depending on the severity of the deficiency of endogenous insulin. Plasma and urine glucose and ketone body measurements remain the practical standards for assessing diabetic control. Abnormalities of lipid and protein metabolites serve to augment the scope of the assessment. Triglycerides and haemoglobin AIc are also useful indicators of control. In mild (Type II) diabetes it may be possible to achieve normal plasma glucose measurements two hours after meals. Such aims carry a risk of hypoglycaemia in severe (Type I) diabetes. Normoglycaemia and aglycosuria in severe diabetes are feasible only preprandially in most cases. The use of urine glucose tests requires evaluation of blood-to-urine glucose relationships. Practical and convenient methods for identifying patients with high or low "renal thresholds" are described. Investigational methods for characterising diabetic patients assess the variability of glucose and other variables during therapy, as well as the degree to which normal values are attained. Such assessment methods may gain increasing practical importance as therapeutic approaches to diabetic control which are experimental at present come into practice.