Lectin histochemistry of pathological bones

Our present knowledge of the structure and function of glycoproteins in bone tissue is very limited. The introduction of lectins into histology offered principally a new approach for studying the presence and chemical structure of glycoproteins in tissue sections. In this paper these highly specific carbohydrate binding molecules have been used to characterize glycoproteins in the cellular elements of normal bone and benign bone lesions. We retrospectively examined 35 benign bone lesions (7 fibrous dysplasias, 5 foreign body granulomas, 5 epulis, 8 osteoid osteomas, 10 giant cell tumors) together with 25 normal bone samples. In normal bone samples and all cases of benign bone lesions, two characteristic types of PNA binding were found after neuraminidase digestion in osteoclasts. In osteoclasts which did not adhere to bone surface, diffuse intracytoplasmic PNA binding was seen, and following the adherence to the bone surface, it disappeared, and the resorption zone became stainable. We assume that this PNA binding glycoprotein is formed in the cytoplasm of osteoclasts, then, after the activation of osteoclasts, the glycoprotein gets accumulated at the resorption zone of the cytomembrane where it plays a significant role in the bone resorption.     

Hyperosmolar D-mannitol reverses the increased membrane excitability and the nodal swelling caused by Caribbean ciguatoxin-1 in single frog myelinated axons

The effects of hyperosmolar D-mannitol were studied on single frog myelinated nerve fibres previously poisoned with Caribbean ciguatoxin-1 (C-CTX-1), a new toxin isolated from the pelagic fish Caranx latus inhabiting the Caribbean region. In current-clamped myelinated axons, C-CTX-1 (50-120 nM) caused spontaneous and repetitive action potential discharges after a short delay. In addition, the toxin produced a marked swelling of nodes of Ranvier of myelinated axons that reached a steady state within about 90 min, as revealed by using confocal laser scanning microscopy. The increased excitability and the nodal swelling caused by C-CTX-1 were prevented or reversed by an external hyperosmotic solution containing 100 mM D-mannitol. Moreover, the C-CTX-1-induced nodal swelling was completely prevented by the blockade of voltage-sensitive sodium channels by tetrodotoxin (TTX). It is suggested that C-CTX-1, by increasing nerve membrane excitability, enhances Na(+) entry into nodes of Ranvier through TTX-sensitive sodium channels, which directly or indirectly disturb the osmotic equilibrium between intra- and extra-axonal media resulting in an influx of water that was responsible for the long-lasting nodal swelling. The fact, that hyperosmolar D-mannitol either reversed or prevented the neurocellular actions of C-CTX-1, is of particular interest since it provides the rational basis for its use to treat the neurological symptoms of ciguatera fish poisoning in the Caribbean area.     

Sex hormones and gender-related differences: their influence on chronic renal allograft rejection

BACKGROUND: Renal hemodynamics and immune responses differ between males and females. Thus, sex hormones and genetically determined gender differences may determine the process of chronic rejection to some extent. METHODS: Female (F) or male (M) F344 kidneys were orthotopically transplanted into ovariectomized female Lewis recipients and were treated for 16 weeks with either estradiol, testosterone, or vehicle. RESULTS: Testosterone treatment resulted in increased urinary protein excretion independently of the donor gender, as well as extended glomerular sclerosis, interstitial fibrosis, and severe vascular lesions. Additionally, mononuclear cell infiltration was most pronounced in these animals, in parallel to an increased expression of intercellular adhesion molecule-1 (ICAM-1), fibronectin, laminin, and transforming growth factor-beta (TGF-beta) in the grafts. Estradiol treatment resulted in an improved graft function, reduced glomerular sclerosis, and a diminished cellular infiltration, in parallel to a reduced ICAM-1, fibronectin, laminin, and TGF-beta expression. In animals treated with vehicle, the gender of the donor influenced the outcome. Grafts of male origin had good graft function and histology, whereas grafts from female donors developed severe proteinuria and glomerular, interstitial, and vascular damage. CONCLUSIONS: These results suggest that a protective effect of estradiol on the progression of chronic rejection exists that is independent of donor gender. Additionally, a male kidney may benefit from the absence of testosterone, whereas the function of a female kidney deteriorates in the absence of estradiol.     

Hyponatremia in the postoperative period after a neurosurgical tumor condition

A four-year-old girl suffered difficult-to-diagnose hyponatremia resistant to treatment following surgery for a suprasellar tumor. The final diagnosis was diabetes insipidus evolving in three stages. Hyponatremia is a common problem following surgery to remove brain tumors. Early diagnosis and treatment of this electrolytic imbalance are essential for preventing serious neurological symptoms or death. The conditions most closely related to hyponatremia are inappropriate antidiuretic hormone secretion syndrome (IADHSS) and cerebral salt wasting syndrome (CSWS). The latter has become more common in recent years among patients undergoing brain surgery. Whereas IADHSS is treated by restricting fluids, CSWS requires administration of salt and volume fluid volume. We believe that for differential diagnosis of postoperative hyponatremia, a fluid restriction test takes priority over of fluid loading following neurosurgery. The course of hyponatremia must be carefully monitored and a complete endocrinological workup must be performed to detect the possible presence of hypophyseal deficiencies, particularly hypothyroidism and suprarenal insufficiency.