Static and dynamic bone changes in hospitalized patients suffering from rickets--a histomorphometric study.

AIMS: The aim of this study was to assess static and dynamic bone changes in patients suffering from rickets. METHODS AND RESULTS: Transcortical iliac crest biopsies of 15 hospitalized children with rickets were taken after labelling new bone formation with two cycles of tetracycline administration 10 days apart. Undecalcified sections were prepared, appropriately stained and histomorphometric analysis performed. Static and dynamic bone changes were measured including the volume of bone and osteoid, trabecular and cortical bone dimensions and resorptive and mineralization activities. The results were compared with normal values. The nature of the mineralization fronts was noted. Trabecular osteoid volumes of all but one patient was above the normal range of 1.9% (+/-0.4%). This patient suffered rickets associated with the Kwashiorkor-Marasmus syndrome. Tetracycline labelling was found to be more sensitive than subjective evaluation of the nature of the mineralization fronts. Despite a balanced hospital diet, a bone formation rate of zero was found in three cases, indicating a need for vitamin D and mineral supplementation. Seven cases had decreased mineralization lag times, indicating response to the balanced diet. CONCLUSIONS: This study showed that histometric analysis of labelled bone biopsies is a helpful adjunct to the diagnosis but particularly assessment of response to management of deficiency states in children.

Parotid salivary gland of the African elephant (Loxodonta africana): structure and composition of saliva.

Specimens from parotid salivary glands of full-grown elephant (Loxodonta africana) a (n=6) and saliva aspirated from their main excretory ducts were examined macroscopically and microscopically and analyzed biochemically. The composition of the saliva was compared to that of the blood. The parotids (n=12; mean = 7.4 kg) are homocrine and of a seromucous nature. Myoepithelial cells are well-developed along intercalated ducts and their processes extend to proximal portions of allied acini. The saliva is hypotonic and contains relatively low concentrations of sodium and glucose and high concentrations of potassium, urea, calcium and phosphorus. Absence of detectable levels of alpha-amylase negates a digestive role and the voluminous secrete evidently aids swallowing by moisturising and lubricating the large mass of ingested leaves, grass and bark.