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Hereditary rickets is increasingly recognized as a major form of skeletal disease in children. This group of disorders results from defects that are considered primary derangements in either calcium or phosphate homeostasis. The clinical, biochemical, and radiographic features of various types of hereditary rickets are described. Establishment of the correct diagnosis of the child presenting with rachitic disease is addressed. Specific therapeutic guidelines and overall treatment strategy are discussed, with a particular emphasis on the most frequently encountered form of hereditary rickets, X-linked hypophosphatemia.

ABSTRACT: Although PTH and hypophosphatemia are the best known stimulators of 25-hydroxyvitamin D-1a-hydroxylase, 1,25(OH)2D3production in rats and humans can be modulated by circulating calcium, independent of PTH. To test whether calcium modulates this function directly in mitochondria, we examined effects of calcium on 1a-hydroxylase in isolated mitochondrial preparations under basal and stimulated conditions. Rats were fed a low phosphorus (or matched control) diet for 4 or 7 d or a vitamin D-deficient (or matched control) diet for 2, 4, or 7 wk. Renal mitochondria were isolated and assayed for 1a-hydroxylase activity in the presence or absence of added calcium. Calcium did not alter 1a-hydroxylase in rats on control diets. After 4 d of low phosphorus diet, 1a-hydroxylase was increased 2-fold over basal activity; media calcium prevented this stimulatory response. By 7 d the calcium effect was not evident. After 4 wk of vitamin D deprivation, activity was ~30-fold greater than controls; calcium reduced this response significantly (15-fold). A significant, but less marked inhibition of activity by calcium was present in rats subjected to 7 wk of vitamin D deprivation. Extramitochondrial calcium can directly modulate 1,25(OH)2D3production, but this effect appears to be secondary to the primary physiologic regulators of this function. The calcium effect can be overcome after longer term exposure to phosphorus deprivation, but is sustained in the presence of long term vitamin D deprivation.

Post‐treatment data were collected on a patient who received intravenous hydroxypropyl β‐cyclodextrin in a dose of 1.5 g/kg in 1985. Although no untoward effects were observed in this patient, rarely occurring agitation and pulmonary edema have been noted after injections into rabbits and dogs, respectively. These complications are analyzed here on the basis of symptoms and on the effects of hydroxypropyl β‐cyclodextrin on the biochemistry of a representative lipid, cholesterol, which were studied in rats. It is hypothesized that these untoward effects of parenteral hydroxypropyl β‐cyclodextrin are due to complex formation, with lipid mediators of pathological responses, of which prostaglandins are one example. These mediators normally have brief and localized functions; if hydroxypropyl β‐cyclodextrin happens to be injected when these mediator systems are activated, their influence and the responses of the organism may be increased.

The purpose of this review was to synthesize the research on the relationship between performance on Piagetian tasks of concrete operations and performance on mathematics learning tasks in order to determine whether the Piagetian tasks make useful readiness measures. The research consistently indicates that, while there is a positive correlation between performance on Piagetian tasks and mathematics achievement, many school mathematics tasks can be mastered by children who have not yet developed the reasoning abilities measured by Piagetian tasks. This does not diminish the validity of Piaget's theory, but rather suggests that the kinds of reasoning processes identified by Piaget are not essential in solving many school mathematics tasks.

We argue that reform in curriculum and instruction should be based on allowing students to problematize the subject. Rather than mastering skills and applying them, students should be engaged in resolving problems. In mathematics, this principle fits under the umbrella of problem solving, but our interpretation is different from many problem-solving approaches. We first note that the history of problem solving in the curriculum has been infused with a distinction between acquiring knowledge and applying it. We then propose our alternative principle by building on John Dewey’s idea of “reflective inquiry,” argue that such an approach would facilitate students’ understanding, and compare our proposal with other views on the role of problem solving in the curriculum. We close by considering several common dichotomies that take on a different meaning from this perspective

Although PTH and hypophosphatemia are the best known stimulators of 25-hydroxyvitamin D-1α-hydroxylase, 1,25(OH)2D3production in rats and humans can be modulated by circulating calcium, independent of PTH. To test whether calcium modulates this function directly in mitochondria, we examined effects of calcium on 1α-hydroxylase in isolated mitochondrial preparations under basal and stimulated conditions. Rats were fed a low phosphorus (or matched control) diet for 4 or 7 d or a vitamin D-deficient (or matched control) diet for 2, 4, or 7 wk. Renal mitochondria were isolated and assayed for 1α-hydroxylase activity in the presence or absence of added calcium. Calcium did not alter 1α-hydroxylase in rats on control diets. After 4 d of low phosphorus diet, 1α-hydroxylase was increased 2-fold over basal activity; media calcium prevented this stimulatory response. By 7 d the calcium effect was not evident. After 4 wk of vitamin D deprivation, activity was ∼30-fold greater than controls; calcium reduced this response significantly (15-fold). A significant, but less marked inhibition of activity by calcium was present in rats subjected to 7 wk of vitamin D deprivation. Extramitochondrial calcium can directly modulate 1,25(OH)2D3production, but this effect appears to be secondary to the primary physiologic regulators of this function. The calcium effect can be overcome after longer term exposure to phosphorus deprivation, but is sustained in the presence of long term vitamin D deprivation.

Hydroxypropyl ethers of cyclodextrins, after parenteral administration, come into contact with lipids in tissues and in circulation and form water‐soluble inclusion complexes with these lipids. A single intravenous administration of hydroxypropyl‐β‐cyclodextrin to a hereditary hyperlipidemic Watanabe rabbit slightly and temporarily decreased the level of total cholesterol in serum. Single injections of hydroxypropyl‐α‐cyclodextrin and of the corresponding γ‐homologue, both of which are less potent solubilizers of cholesterol, had lesser effects. Repeated administration of hydroxypropyl‐β‐cyclodextrin to rabbits led to a gradual increase in total cholesterol in circulation and eventually to a slight relief of atherosclerotic lesions in the thoracic aorta. The only untoward effects of repeated treatments (total doses of up to 40 g/kg) were vacuoles in cells of proximal convoluted tubules in the kidneys. Repeated administration also strongly increased cholesterol in urine, probably because of excretion of the soluble cholesterol‐hydroxypropyl‐β‐cyclodextrin complex. Proteins in urine increased significantly, whereas triglycerides increased only moderately after repeated administrations. Intravenous infusion of hydroxypropyl‐β‐cyclodextrin into a patient with hypervitaminosis A led to a release of liver‐stored retinoids into serum in quantities much higher than those that could be directly solubilized by hydroxypropyl‐β‐cyclodextrin. Levels of total cholesterol in the circulation of this patient decreased during the infusion. Thus, hydroxypropylcyclodextrins may serve as artificial lipid carriers in the circulation, and because the exchanges that involve inclusion complexation occur very quickly, the presence of hydroxypropylcyclodextrins in organisms may catalytically augment the establishment of equilibria in lipid distribution.

Thirty-eight first grade teachers were asked to identify their two most and least successful girls and boys in mathematics, to attribute causation of these students' successes and failures, and to describe their characteristics. Teachers' choices of most and least successful students were compared to mathematics test scores of their students. Teachers were most inaccurate when selecting most successful boys. Teachers tended to attribute causation of boys' successes and failures to ability and girls' successes and failures to effort. Teachers thought their best boy students when compared to their best girl students, were more competitive, more logical, more adventurous, volunteered answers more often to mathematics problems, enjoyed math more, and were more independent in mathematics.

Negative beliefs about disability are associated with poorer outcomes for individuals with disabilities; understanding disability-related attitudes is critical for clinical care. Recently, interest in attitudes toward people with disabilities has increased; however, most studies focus on explicit attitudes. In contrast, the Disability Attitude Implicit Association Test (DA-IAT) is designed to evaluate respondents’ underlying automatic preferences regarding physical ability.

An adolescent with hypophosphatemic rickets developed cardiac calcifications in the absence of hypercalcemia or elevation of the phosphocalcic product (the product of the total serum calcium and phosphorus concentrations). Cardiac calcifications led to aortic and mitral valve dysfunction, myocardial calcification, and arrhythmia. Hyperparathyroidism probably played a significant role in the development of this complication, which emphasizes the necessity for intermittent assessment of parathyroid status in individuals receiving medical therapy for hypophosphatemic rickets.