Early effects of synthetic bovine parathyroid hormone and synthetic salmon calcitonin on urinary excretion of cyclic AMP, phosphate and calcium in man

Palimpsests and urban pasts: The janus-faced nature of whitechapel

This article examines how palimpsests in city spaces are mediated and negotiated by pedestrians' individual everyday experiences. The literature on city spaces and palimpsests is rich; however, it has not examined the sharing and fusing of palimpsests into everyday life. To fill this lacuna, we explore how pedestrians mediate the physical path of the parcellations and the layers of meanings accrued over the years. We describe what we term the "Janus face of Whitechapel Road" that characterizes the multidimensional and ever-changing face of London as a world city. We look at the different traffic hinges distributed throughout the urban setting and track people as they encounter these historical and aesthetic landmarks. The experience of London's palimpsests is an exemplar of this Janus's face, governed by transitions, time, duality, and passages.

Salmon calcitonin and cGMP production by human kidney: studies in vivo and in vitro

In order to evaluate whether or not the action of salmon calcitonin (sCT) at the kidney level could be mediated through specific receptors for the hormone, we have studied the effects of sCT infusions on urinary excretion of cyclic nucleotides in humans. Parallel in vitro studies have been conducted by evaluating the effects of sCT on cyclic nucleotide levels in primary cultures of cortical and medullary human kidney cells. In vivo experiments showed that sCT induced an increase in cGMP in human urine, which was rapid and short-lasting, being superimposable on the increase of urinary excretion of calcium and magnesium. The increase of inorganic phosphate urinary excretion was delayed and appeared to parallel that of urinary cAMP. On the other hand, our in vitro experiments showed that sCT stimulated the guanylate cyclase-cGMP system of human kidney cortical cells at nanomolar concentrations, while higher concentrations of the hormone were required to activate the adenylate cyclase-cAMP system. In addition, sCT was not able to significantly modify the cellular levels of either nucleotide in human kidney medullary cells. Present data demonstrated a direct effect of sCT on human kidney cortical cGMP production, while the efficacy of sCT on the kidney cortex adenylate cyclase-cAMP system appears to be delayed and/or reduced.

The 24-h urinary cyclic adenosine 3', 5' monophosphate/creatinine ratio: an useful approach to the diagnosis of parathyroid disorders and function

24-h urinary cyclic adenosine 3', 5'-monophosphate/creatinine (cAMP/Cr) ratio was assessed in 10 patients with hypoparathyroidism, 6 with primary hyperparathyroidism, 7 with normocalcemic hypercalciuria and recurrent nephrolithiasis, 14 with osteomalacia, 25 with Paget's disease and 53 with symptomatic postmenopausal osteoporosis. In hypoparathyroid subjects the mean values of 24 h cAMP/Cr ratio were significantly lower than the control values, whereas in patients with parathyroid adenoma the mean values were higher and fell after parathyroid surgery. Patients with nephrolithiasis due to absorptive hypercalciuria showed low or normal cAMP/Cr ratio, whereas in those with osteomalacia and mean values of cAMP/Cr ratio were significantly higher than the control values and decreased after vitamin D treatment. The mean value of the 24 h urine cAMP/Cr ratio was normal in patients with Paget's disease or postmenopausal osteoporosis and increased significantly after long term treatment with calcitonin or diphosphonate. This increase paralleled a significant decrease of calcium plasma level. A significant improvement of fractional calcium absorption was observed in women with postmenopausal osteoporosis at the end of treatment with calcitonin or diphosphonate.

Effects of parathyroid hormone and calcitonin on plasma and nephrogenous cyclic adenosine-3',5'-monophosphate in normal subjects and in pathological conditions

To evaluate the response of bone cells and kidney to parathyroid hormone (PTH) and calcitonin (CT), the acute effects of these hormones given intravenously on plasma cyclic adenosine 3',5'-monophosphate (cAMP), nephrogenous cAMP and clearance ratio (cAMP:creatinine), have been studied in normal subjects and in patients with Paget's disease, hypoparathyroidism and osteopetrosis. Twenty-five subjects were given bovine synthetic PTH, thirty-eight calcitonin (sixteen salmon, eighteen human and four porcine CT). In normal subjects and in patients with Paget's disease and hypoparathyroidism plasma cAMP increased within 1 h following PTH intravenous infusion. The same dose of PTH failed to produce any increase in plasma cAMP level in two children with marble bone disease. Nephrogenous cAMP increased in all cases. A different relative potency of calcitonins in increasing plasma cAMP has been observed in normal subjects, according to previous results on the plasma calcium lowering effect. Paget's disease patients showed a greater increase in plasma cAMP following infusion than normal subjects. The measurement of nephrogenous cAMP and the clearance ratio (cAMP: creatinine) demonstrated a minor involvement of the kidney in the production of cAMP after CT infusion; the late increase observed in nephrogenous cAMP was probably due to a parathyroid rebound following the hypocalcemic effect of CT.