CHANGES IN CALCIUM CONCENTRATIONS OF SERUM AND COELOMIC FLUID OF THE BULLFROG, RANA CATESBEIANA, DURING LARVAL DEVELOPMENT AND METAMORPHOSIS

The serum calcium levels of bullfrog tadpoles (stage 26 to 33) and adults are higher than those of the coelomic fluid. The serum levels increase gradually from stage 26 (7.6 mg/100 ml) to stage 30 (8.4 mg/100 ml), and then sharply to stage 33 (10.5 mg/100 ml), while the coelomic fluid levels increase from 7.1 to 8.7 mg/100 ml during this period. Only minor differences are found in serum and coelomic fluid sodium levels among larval stages with the exception of a temporary decrease during metamorphic climax.
These results suggest that the adult type of regulation of serum calcium concentrations is established during larval development and is fully achieved after the completion of metamorphosis. The control mechanism for serum calcium may be different from that for coelomic fluid.     

Effect of aluminium hydroxide on serum ionised calcium,immunoreactive parathyroid hormone,and aluminium in chronic renal failure.

According to the Bricker-Slatopolsky theory, secretion of parathyroid hormone (PTH) is switched on in chronic renal failure by hypocalcaemia due to phosphate retention. In an attempt to reverse this process 20 patients in preterminal renal failure (plasma creatinine 569 +/- 195 mumol/l) were given aluminium hydroxide, 3.8 g daily. They were studied for four weeks and all measurements were made at the start and weekly, except measurements of serum aluminium concentration, which were made at the start and at the end of the fourth week. Mean serum phosphate fell from 1.89 to 1.47 mmol/l (5.9 to 4.6 mg/100), mean serum calcium rose from 2.07 to 2.24 mmol/l (8.3 to 9.0 mg/100 ml), and serum ionised calcium rose from 1.07 to 1.20 mmol/l (4.3 to 4.8 mg/100 ml), but serum immunoreactive PTH did not fall. Thirteen patients had initial serum immunoreactive PTH concentrations at or near to normal and 11 were taking beta-blockers but even in those with neither explanation, PTH concentrations did not fall. Serum aluminium concentrations rose from 0.4 to 1.02 mumol/l (10.9 to 27.4 microgram/l). Aluminium hydroxide corrects serum phosphate, total calcium, and ionised calcium at the price of a rise in serum aluminium concentration; in this study it did not affect serum immunoreactive PTH. The Bricker-Slatopolsky theory still needs verification in studies of patients with chronic renal failure.     

Urine calcium concentrations in bullfrog tadpoles kept in tap water or high calcium environment, with special reference to ultimobranchialectomy

1. Urine calcium concentrations were determined in intact and ultimobranchialectomized bullfrog tadpoles kept in tap water (Ca: 8.5 and 19.7 mg/100 ml), urine calcium levels did not show significant increases. 3. In ultimobranchialectomized tadpoles, hypercalciuria concomitant with the rise in serum calcium levels in recognized under both conditions of high calcium water and tap water. 4. It was suggested that in bullfrog tadpoles ultimobranchial glands do not exert effective influences on the renal handling of calcium.     

Improvement and initial in vivo application of the radioimmunoassay of rat thyrocalcitonin.

Previously we reported a homologous radioimmunoassy for rat thyrocalcitonin (TCT) which was sensitive enough (2--3 ng/ml serum) to measure TCT in thyroid venous blood or thyroid gland extracts but could not detect TCT in peripheral blood even after provocative challenge with iv calcium. In the present study chicken antisera to rat TCT were developed which were sufficiently sensitive (120--240 pg/ml serum) to permit initial evaluation of changes in TCT in rat peripheral blood. The following results were observed: (1) Basal serum TCT in young male Holtzman rats was undetectable, being less than 120--240 pg/ml; (2) induction of marked hypercalcemia by iv calcium increased TCT to approximately 1000--3000 pg/ml within 5 min; (3) thyroid cautery increased TCT to approximately 1000 pg/ml in 5--15 min; (4) calcium gavage (12.2 mg Ca/100 g) produced modest hypercalcemia in 30--60 min and increased serum TCT to approximately 500 pg/ml; (5) injection of isoproterenol raised serum TCT detectably; (6) injection of large doses of gastrin or pentagastrin did not produce detectable increases in TCT 5 or 30 min later. The results show that suitable antisera to rat TCT can be developed in chickens and applied to the measurement, by radioimmunoassay, of elevated circulating levels of TCT in the rat.     

Responses to the lowering of magnesium and calcium concentrations in the cerebrospinal fluid of unanesthetized sheep.

A technique for ventriculolumbar perfusion of the cerebrospinal fluid space has been used to study the neuromuscular effects of low concentrations of magnesium and calcium in the cerebrospinal fluid of conscious sheep. Perfusion with synthetic cerebrospinal fluid solutions containing less than 0-6 mg magnesium/100 ml produced episodes of tetany which were abolished by perfusion with a solution of normal magnesium concentration. This suggests that the low cerebrospinal fluid magnesium concentrations reported in cases of hypomagneseamic tetany may result in changes within the central nervous system that could produce the nervous signs. Perfusates with a calcium concentration below 2-0 mg/100 ml caused hyperpnoea and continuous muscle tremors. Magnesium (0-6 mg/100 ml) and calcium (2-0 mg/100 ml) perfused simultaneously acted synergistically to produce signs characteristic of low levels of each of the ions.     

Characterization of calcium accumulation in the brain of rats administered orally calcium: The significance of energy-dependent mechanism

The characterization of calcium accumulation in the brain of rats administered orally calcium chloride solution was investigated. Rats received a single oral administration of calcium (15–50 mg/100 g body weight), and they were sacrificed by bleeding-between 15 and 120 min after the administration. The administration of calcium (50 mg/100 g) produced a significant increase in serum calcium concentration and a corresponding elevation of brain calcium content, indicating that the transport of calcium into the brain is associated with the elevation of serum calcium levels. The increase in brain calcium content by calcium administration was not appreciably altered by the pretreatment with Ca²⁺ channel blockers (verapamil or diltiazem with the doses of 1.5 and 3.0 mg/100 g). In thyroparathyroidectomized rats, the administration of calcium (50 mg/100 g) caused a significant increase in brain calcium content, indicating that calcium-regulating hormones do not participate in the brain calcium transport. Now, brain calcium content was clearly elevated by fasting (overnight), although serum calcium level was not significantly altered. Calcium administration to fasted rats induced a further elevation of brain calcium content as compared with that of control (fasted) rats. The fasting-induced increase in brain calcium content was appreciably restored by refeeding. This restoration was also seen by the oral administration of glucose (0.4 g/100 g) to fasted rats. The present study demonstrates that serum calcium is transported to brain, and that the increased brain calcium is released promptly. The release of calcium from brain may be involved in energy metabolism, and this release may be weakened by the reduction of glucose supply into brain. The finding suggests a physiological significance of energy-dependent mechanism in the regulation of brain calcium.     

Variation in Plasma Calcium with Induced Changes in Plasma Specific Gravity,Total Protein,and Albumin

The relationship of plasma calcium levels to changes in plasma specific gravity, total protein, and albumin induced by venous stasis was investigated. Factors were derived for adjusting calcium results to offset the effects of variation in protein concentration and thus to make them of increased discriminatory value to the clinician. The validity of an existing specific gravity correction has been substantiated, but a more exact adjustment of 0·23 mg/100 ml of calcium for every 0·001 change in specific gravity is proposed. We recommend for automated laboratories that the factor based on albumin be used: 0·09 mg/100 ml of calcium should be subtracted from the total calcium value for every increase of 0·1 g in albumin above 4·6 g/100 ml, and a corresponding addition should be made for values of albumin below 4·6 g/100 ml.Using a calcium specific electrode, it has been shown that the ionized calcium concentration does not alter with prolonged venous stasis.     

Long term follow up of untreated primary hyperparathyroidism.

Fourteen patients with primary hyperparathyroidism and whose initial serum calcium concentrations were 2.75 mmol/l (11.0 mg/100 ml) or more were followed up for five to 23 years without operative treatment. One had osteitis fibrosa when seen and died with a fibrosarcoma 22 years later. The remaining 13 patients, who were followed up for a mean of 10 years, came to little obvious harm from not being operated on. Their serum calcium concentrations did not rise and there was no evidence of progressive renal impairment. In four patients who presented originally with renal calculi there were three further episodes of renal colic in 54 patient years of follow up. Conservative management of primary hyperparathyroidism is not an unreasonable option, and patients who do not have symptoms need not necessarily be pressed to accept surgery.     

A patient of short stature with idiopathic hypoparathyroidism round face and metacarpal signs

A 16-year old girl of short stature, with round face, mental retardation, and Albright's dimple sign was admitted for evaluation of hypocalcemia. Her serum calcium levels were 6.3-8.0 mg/dl, and phosphorus 6.9-7.8 mg/dl. Although a diagnosis of pseudohypoparathyroidism was initially suggested, her serum iPTH concentration was low (0.1 ng/ml). Furthermore, an injection of synthetic human parathyroid hormone (100 U, hPTH (1-34] was followed by a marked increase in urinary excretion of cyclic AMP and phosphorus. This case suggests that a shortened metacarpal is not a reliable guide in distinguishing between idiopathic hypoparathyroidism and pseudohypoparathyroidism and that a standard Ellsworth-Howard test is a prerequisite to differential diagnosis.     

The effect of experimental induced hypocalcaemia on uterine activity in the sow during parturition and post-partum

Uterine activity was measured by monitoring intrauterine pressure changes using ballon-tipped catheters placed in the lumen. An infusion rate of Na(2)EDTA of 35 mg/Kg/h gave a chelation rate equivalent to the rate of calcium mobilisation, and when infused at a level greater than this, resulted in a reduction in plasma calcium concentrations and a concomitant reduction in uterine activity. In three of the four sows infused intrapartum, there was complete cessation of uterine activity; however, plasma calcium concentrations of less than 6 mg 100 ml resulted in a reduction in uterine activity at this stage of parturition. The uterus of the sow post-partum appeared to be more sensitive to the effects of hypocalcaemia with reduced uterine activity when plasma calcium concentrations fell below 8.2 mg 100 ml and complete cessation of activity between 6 and 7 mg 100 ml . Although there was evidence of a delay in the expulsion of piglets in the hypocalcaemic sows, there was no evidence of an increased number of stillborn piglets compared with the two control sows.     

Silymarin modulates Cisplatin-induced oxidative stress and hepatotoxicity in rats

Cisplatin (CDDP) is a widely used anticancer drug, but at high dose, it can produce undesirable side effects such as hepatotoxicity. Because silymrin has been used to treat liver disorders, the protective effect of silymarin on CDDP-induced hepatotoxicity was evaluated in rats. Hepatotoxicity was determined by changes in serum alanine aminotransferase [ALT] and aspartate aminotransferase [AST], nitric oxide [NO] levels, albumin and calcium levels, and superoxide dismutase [SOD], glutathione peroxidase [GSHPx] activities, glutathione content, malondialdehyde [MDA] and nitric oxide [NO] levels in liver tissue of rats. Male albino rats were divided into four groups, 10 rats in each. In the control group, rats were injected i.p. with 0.2 ml of propylene glycol in saline 75/25 (v/v) for 5 consecutive days [Silymarin was dissolved in 0.2 ml of propylene glycol in saline 75/25 v/v]. The second group were injected with CDDP (7.5 mg /kg, I.P.), whereas animals in the third group were i.p. injected with silymarin at a dose of 100 mg/kg/day for 5 consecutive days. The Fourth group received a daily i.p. injection of silymarin (100 mg/kg/day for 5 days) 1 hr before a single i.p. injection of CDDP (7.5 mg/kg). CDDP hepatotoxicity was manifested biochemically by an increase in serum ALT and AST, elevation of MDA and NO in liver tissues as well as a decrease in GSH and the activities of antioxidant enzymes, including SOD, GSHPx in liver tissues. In addition, marked decrease in serum NO, albumin and calcium levels were observed. Serum ALT, AST, liver NO level, MDA was found to decreased in the combination group in comparison with the CDDP group. The activities of SOD, GSHPx, GSH and serum NO were lower in CDDP group than both the control and CDDP pretreated with silymarin groups. The results obtained suggested that silymarin significantly attenuated the hepatotoxicity as an indirect target of CDDP in an animal model of CDDP-induced nephrotoxicity.     

Influence of parathormone on C cells, parathyroid glands, serum calcium and serum phosphate levels in the house shrew, Suncus murinus

A chronic hypercalcaemia was induced in Suncus murinus by the daily subcutaneous injections of parathormone for 15 days. Serum calcium increased 4 hours after the first injection (+ 0.88 mg/100 ml), it reached its highest value on day 10 (+ 2.18 mg/100 ml), and then decreased slightly at the end of the experiment (day 15). The serum phosphate level in treated animals showed a progressive fall throughout the experiment. Serial sections of thyroid-parathyroid complex were subjected to selective staining for C cells identification. The chronic hypercalcaemia increased the number of C cells. This was supported by the presence of mitotic figures. Degranulation of the secretory material was observed as the result of the chronic hypercalcaemia; degenerative changes were found in some C cells. The chronic hypercalcaemia also inhibited the activity of parathyroid "Chief-Cells" which ultimately degenerated.     

Effect of estrogens on renal responsiveness to parathyroid hormone in elderly female subjects

The effect of estrogens on the renal responsiveness to parathyroid hormone (PTH) was examined by PTH loading tests with synthetic human-PTH (1-34) in 8 normal elderly females (mean +/- SD age, 81.0 +/- 7.1 yr) before and after administration of estrogen (Premarin 1.25 mg/day for 4 weeks). Basal urinary adenosine cyclic 3', 5'-monophosphate (cAMP) excretion showed a tendency to increase after estrogen administration (5.47 +/- 1.68 vs 6.60 +/- 2.67 nmol/100 ml GFR) and the theoretical renal phosphorous threshold showed a tendency to decrease from 3.22 +/- 0.98 to 2.73 +/- 0.56 mg/dl. The blood ionized calcium concentration did not change after estrogen administration (4.44 +/- 0.16 vs 4.32 +/- 0.20 mg/dl) and serum phosphorous (P) decreased significantly (3.65 +/- 0.47 vs 3.01 +/- 0.42 mg/dl, p less than 0.05). There was no increase in mean serum immunoreactive PTH (0.34 +/- 0.10 vs 0.34 +/- 0.05 ngeq/ml). The urinary excretions of cAMP in response to PTH loading [100 U of human-PTH (1-34), intravenously] significantly (p less than 0.05) increased (94.8 +/- 57.0 vs 196.7 +/- 118.3 nmol/100 ml GFR/h) after estrogen administration. Moreover the changes in urinary excretion of cAMP (r = 0.698, p less than 0.01) and P (r = 0.555, p less than 0.05) induced by the PTH loading were positively correlated with serum estradiol in elderly females, assessed as groups before and after estrogen administration. These results suggest that estrogens may enhance the renal responsiveness to exogenous PTH administration.     

Seasonal changes in reproductive function of the rainbow trout (Salmo gairdneri)

The sequential changes in serum oestradiol 17β (measured by specific radioimmunoassay), vitellogenin (measured by phosphoprotein phosphorus content) and total calcium (measured by fluorimetry) in male and female rainbow trout under a simulated natural photoperiod cycle were investigated. Resting levels of 130 pg/ml serum oestradiol in both male and female fish were found in April and May. In the female, levels reached a peak of 4800 pg/ml in October, and almost returned to resting levels just prior to spawning in mid-January. No significant change from resting levels was seen in the male fish.
In both male and female fish levels of 25 μg/ml serum phosphoprotein phosphorus and 10–14 mg % total serum calcium were found from April to July. Coincident with the rise in oestradiol 17β, in the females serum levels of phospho-protein phosphorus and total calcium increased to 400 uβg/ml and 58 mg% respectively just prior to spawning. In the males no significant change in either of these values was observed throughout the cycle. These results strongly support the hypothesis that photoperiod is the major factor in the environmental control of reproductive activity in the rainbow trout.     

Serum Lipids in Cholelithiasis: Effect of Chenodeoxycholic Acid Therapy

Hypercholesterolaemia has been predicted as a possible complication of chenodeoxycholic acid treatment for gall stones. To exclude this, fasting serum lipids were measured in patients with stones before and at monthly intervals for six months after starting chenodeoxycholic acid. Before treatment half of a group of 36 patients with presumed cholesterol gall stones had serum cholesterol levels exceeding 260 mg/100 ml or serum triglyceride values greater than 160 mg/100 ml or both; these lipid levels were significantly greater than those in control subjects matched for age and sex. Treatment with chenodeoxycholic acid (0·5-1·5 g/day by mouth) did not change serum cholesterol levels but did significantly reduce serum triglyceride concentrations from a pretreatment level of 118 (± S.E. of mean 11·7) mg/100 ml to 95 (± 7·2) mg/100 ml after six months of therapy. The mechanism of this triglyceride-lowering action of chenodeoxycholic acid is not known, but it may have therapeutic value in patients with hypertriglyceridaemia.     

Hypercalcemia in glucocorticoid withdrawal

We found severe hypercalcemia in the course of hydrocortisone withdrawal in a patient who had undergone unilateral adrenalectomy to resect a cortisol-hypersecreting adenoma. Serum calcium gradually but progressively increased after unilateral adrenalectomy. Severe hypercalcemia developed on the 77th postoperative day (the 15th day after discontinuing hydrocortisone replacement). The serum concentration of calcium, PTH, 25(OH)D, and 1,25(OH)2D were 8.0 mEq/l, less than 100 pg/ml, 10.1 ng/ml and 29.6 pg/ml, respectively. This hypercalcemia was accompanied by marked urinary hydroxyproline excretion and less calcium excretion in the urine than the prevailing level of serum calcium. Serum concentrations of 25(OH)D, 1,25(OH)2D and PTH were not elevated during the severe hypercalcemia. We concluded that the hypercalcemia in this patient was due in part to enhanced bone resorption and increased renal tubular reabsorption of calcium as a result of glucocorticoid withdrawal, but not to the elevation of serum PTH or serum 25(OH)D and serum 1,25(OH)2D.     

Human fibroblast growth factor-23 mutants suppress Na+-dependent phosphate co-transport activity and 1alpha,25-dihydroxyvitamin D3 production

The human fibroblast growth factor 23 (hFGF23) and its autosomal dominant hypophosphatemic rickets (ADHR) mutant genes were incorporated into animals by naked DNA injection to investigate the action on phosphate homeostasis in vivo. The hFGF23 mutants (R176Q, R179Q, and R179W) markedly reduced serum phosphorus (6.2-6.9 mg/dl) compared with the plasmid MOCK (8.5 mg/dl). However, native hFGF23 did not affect serum phosphorus (8.6 mg/dl). Both hFGF23 and hFGF23R179Q mRNAs were expressed more than 100-fold in the liver 4 days after injection, however, the C-terminal portion of hFGF23 was detected only in the serum from hFGF23R179Q-injected animals (1109 pg/ml). hFGF23R179Q mutant was secreted as a 32-kDa protein, whereas, native hFGF23 was detected as a 20-kDa protein in the cell-conditioned media. These results suggest the hFGF23R179Q protein is resistant to intracellular proteolytic processing. The hFGF23R179Q suppressed Na/P(i) co-transport activities both in kidney and in small intestine by 45 and 30%, respectively, as well as serum 1alpha,25-dihydroxyvitamin D(3) to less than 15 pg/ml. However, it had little effect on serum parathyroid hormone (PTH). Infusion of hFGF23R179Q protein normalized serum phosphorus in thyroparathyroidectomized rats without affecting serum calcium. Taken together, the FGF23 mutants reduce both phosphate uptake in intestine and phosphate reabsorption in kidney, independent of PTH action.     

Ontogeny of tracheal fluid, pulmonary surfactant, and plasma corticoids in the fetal lamb.

We examined fetal plasma corticoids and flow rate, electrolyte composition, and surfactant content of tracheal fluid in chronic experiments with eight fetal lambs. From 120 to 148 days of gestation the rate of fluid production was 4.5 ml/kg per h, and there was no change in mean fluid sodium (147.8 meq/1), chloride (153.1 meq/1), calcium (2.2 mg/100 ml), and pH (6.23). Tracheal fluid potassium increased from 4.3 meq/1 at 120-130 days to 8.9 meq/1 at term, while plasma sodium, chloride, calcium, pH, and potassium were constant at 146.1 meq/1, 110.0 meq/1, 12.1 mg/100 ml, 7.39, and 4.0 meq/1, respectively. Plasma corticoids were less than 1.5 mug/100 ml total (0.3 mug/100 ml free) until 130 days, when they increased rapidly to 10.5 total (3.2 free) at 148 days. Surfactant was first detected in tracheal fluid between 124 and 133 days and its secretion increased rapidly after 135 days to a value of 125 mug/kg per h at 148 days. A sudden increase in fetal plasma corticoids does not seem to be the stimulus for appearance of surfactant in the lamb, although these hormones may induce the rapid accumulation of surfactant prior to delivery.     

Effect of pentobarbital and urethane on the release of hypothalamic somatostatin and pituitary growth hormone

Hypothalamic somatostatin release was investigated in the rat to elucidate the mechanism of anesthetic action on growth hormone (GH) release from the pituitary. Intraperitoneal injection of sodium pentobarbital (5 mg/100 gm B.W.) significantly elevated serum GH levels and increased hypothalamic somatostatin concentration from basal values of 0.98 +/- 0.01 to 1.21 +/- 0.06 ng/mg wet wt. In contrast, urethane (150 mg/100 gm B.W., IP) administration lowered serum GH levels and hypothalamic somatostatin concentration (0.64 +/- 0.04 ng/mg wet wt.). However, the mean concentration of pancreatic somatostatin showed no change in either case. In rats receiving passive immunization with 0.5 ml rabbit antiserum to somatostatin (SRIF-AS), serum GH levels were significantly increased (67.5 +/- 12.3 ng/ml) and did not differ from those in the group treated with normal rabbit serum (NRS) plus pentobarbital (101.3 +/- 18.5 ng/ml). However, serum GH levels in rats injected with SRIF-AS plus pentobarbital were increased to higher values than in rats given SRIF-AS alone. When urethane was administered to rats after passive immunization with SRIF-AS, urethane-induced suppression of serum GH levels was markedly inhibited (5.5 +/- 2.0 vs. 33.5 +/- 7.5 ng/ml). These results suggest a possibility that the changes in serum GH levels observed with pentobarbital or urethane administration may be induced at least in one part by somatostatin released from the hypothalamus.     

Optimum Calcium Concentration of Dialysis Fluid for Maintenance Haemodialysis

To define the minimum and maximum levels for calcium concentration of dialysis fluid a combination of acute and long-term observations was carried outIn acute experiments the external calcium balance during dialysis was dependent on the gradient between plasma ultrafilterable calcium and dialysis fluid calcium concentration. Changes in plasma calcium during dialysis did not correlate with measured external balance.In long-term studies it was found that raising the dialysis fluid calcium concentration from 5.0 to 6.0 mg./ 100 ml. both arrested biochemical and radiological changes of hyperparathyroidism, and, by causing a progressive fall in plasma phosphates, made metastatic calcification less likely. Raising the concentration to 6.5 mg./lOO ml. in an attempt to compensate for negative alimentary calcium balance caused nausea and vomiting in some patients.A concentration of 6.0±0.2 mg./100 ml. is recommended.