Effects of gastrin on calcium homeostasis in chickens

As in the rat, gastrin and an extract of the acid-producing part of the stomach (proventriculus) were found to lower the blood Ca2+ concentration in the chicken. Furthermore, gastrin enhanced the uptake of 45Ca into the femur. It has been suggested previously that gastrin causes hypocalcemia in the rat by releasing gastrocalcin, a hypothetical hormone thought to reside in the acid-producing part of the stomach. The results of the present study in the chicken are in agreement with this concept. Not only exogenous, but also endogenous gastrin lowered blood calcium levels. Thus, the serum gastrin concentration was increased in response to ranitidine-evoked blockade of the gastric acid output; the rise in gastrin was associated with a transient drop in blood calcium. Also, food intake produced a rise in the serum gastrin concentration and a transient drop in blood calcium. However, injection of ranitidine or food intake in proventriclectomized (acid-producing part of the stomach extirpated) chickens failed to lower blood calcium, supporting the view that the gastrin-evoked hypocalcemia depends upon an agent in the gastric (proventriculus) mucosa. We suggest that endogenous and exogenous gastrin evoke hypocalcemia in the chicken by the same mechanism as that which has been postulated in the rat, i.e. by mobilization of the candidate hormone gastrocalcin from endocrine cells in the acid-producing gastric mucosa.     

Post-gastrectomy osteopenia in the rat: bone structure is preserved by retaining 10%-30% of the oxyntic gland area

BACKGROUND: The acid-producing part of the rat stomach (fundus) is rich in endocrine cells, i.e. ECL cells and A-like cells. The ECL cells operate under gastrin control and manufacture histamine, the chromogranin-derived peptide pancreastatin and an unidentified peptide hormone. The A-like cells produce ghrelin, a newly discovered growth hormone-releasing hormone. Surgical removal of the entire glandular stomach (gastrectomy, Gx) or the acid-producing part (fundectomy, Fx) causes osteopenia, which is striking in the calvaria. We speculate that the osteopenia develops after surgical removal of the fundus, because the fundus hosts agents that preserve bone. This study examines how much of the fundus is needed to preserve normal skull bone. METHODS: Increasing portions of the fundus were resected surgically. The serum gastrin, ghrelin and pancreastatin concentrations were measured. The rats were killed after 10 weeks and the calvariae were subjected to transillumination analysis and quantitative histomorphometry. RESULTS: Fx elevated serum gastrin in proportion to the amount of fundus resected, i.e., the more fundus that was resected, the higher the serum gastrin concentration. Serum ghrelin and pancreastatin concentrations were reduced proportionally to the amount of fundus resected. In rats subjected to 90% or 100% Fx, the calvariae displayed the anticipated pattern of bone loss. No bone loss was seen when 70% or less of the fundus was resected. CONCLUSIONS: The results of the present study indicate that 10%-30% of the fundic mucosa is needed to preserve bone. The Gx/Fx-evoked osteopenia may be explained by hormonal deficiency caused by surgically eliminating or diminishing one of the endocrine cell populations in the fundic mucosa.     

Gastrectomy has no effect on bone regeneration in rats despite a decrease in bone mass

BACKGROUND: Gastrectomy, specifically the removal of the acid-producing part of the stomach (fundectomy), is known to cause osteopenia. This effect has been ascribed to the elimination of a hypothetical osteotropic peptide hormone, presumably produced in the oxyntic mucosa. Since osteopenia is due to a disturbed balance between bone formation and resorption, we assessed the effect of gastrectomy on osteogenesis, more specifically mandibular orthotopic bone regeneration. METHODS: Adult rats were either gastrectomized or sham-operated. Two weeks later, unilateral 5-mm transosseous defects were made in the mandibles and covered with microporous barrier membranes (GORE-TEX Membrane). After 6 weeks of healing. bone-bridging of the defects was analyzed by computerized light microscopic image analysis. Furthermore, bone mass was analyzed in the contralateral untreated mandibular side, in calvarial bone, and in femora by morphometry and dry/ash weights. RESULTS: While gastrectomy resulted in a clearly decreased bone mass, manifested as increased marrow spaces in all bones and as decreased dry and ash weights in femora, no difference in mandibular bone healing rate was found between the groups. CONCLUSIONS: Since secluding of the defect space by membrane barriers implies that osteogenic cells have to be recruited primarily from intra-osseous stem cells by their proliferation and differentiation into actively bone-forming osteoblasts, the results indicate that gastrectomy has no effect on these processes. The findings thus imply that the disturbed balance in bone remodeling caused by gastrectomy, resulting in osteopenia, may be due to stimulated bone resorption rather than to reduced bone formation.     

Amylin in bone conservation current evidence and hypothetical Considerations.

Amylin, a 37-amino-acid long single-chain polypeptide, is structurally homologous to calcitonin and calcitonin gene-related peptide (CGRP). The peptide is secreted from pancreatic beta cells and is thought to have an anti-insulin action. Here, we review the recently described effects of amylin on calcium homeostasis and discuss its possible role in bone conservation. Amylin is a potent hypocalcemic and antiresorptive peptide. Studies using isolated osteoclasts have revealed that amylin inhibits cell motility (Q effect), without affecting cell spread area or elevating cytosolic [Ca(2+)]. Thus, amylin action is similar to that of calcitonin, but lower in potency. Lower circulating concentrations of amylin in type-1 diabetes may cause the bone loss associated with this condition.     

Importance of the stomach in maintaining calcium homoeostasis in the rat.

The stomach helps to maintain calcium homoeostasis by making dietary calcium accessible for uptake in the intestines, although the effect of the stomach on calcium homoeostasis is poorly understood. We examined the effect on blood calcium of gastric surgery in the rat. Within three weeks gastrectomy and fundectomy (excision of the acid producing part of the stomach) induced a slight lowering of the blood calcium concentration. When parathyroidectomy was combined with either gastrectomy or fundectomy the blood calcium concentrations promptly dropped to values lower than after parathyroidectomy alone. The mortality was close to 100% during the first three weeks after combined parathyroidectomy and gastric surgery. It was nil in rats subjected to parathyroidectomy alone. Gastrectomised rats absorbed Ca2+ better than unoperated control rats, possibly reflecting the fact that the serum 1,25-dihydroxyvitamin D concentration was raised. Gastrectomised rats had a food intake that was about 70% of that in intact rats, and the amount of dietary calcium absorbed (net absorption per kg body weight) by the gastrectomised rats was approximately 65% of that in intact control rats. We conclude that the acid producing part of the stomach is important for calcium homoeostasis, since its removal induced lethal hypocalcaemia in parathyroidectomised rats. One possible explanation for the hypocalcaemia induced by gastrectomy is a progressive calcium deficit. In addition, the loss of calciotrophic hormones originating in the stomach may contribute.     

Evaluation of Pepsinogen A and Gastrin-17 as Markers of Gastric Cancer and High-Risk Pathologic Conditions

Hallissey MT, Dunn JA, Fielding JWL. Evaluation of pepsinogen A and gastrin-17 as markers of gastric cancer and high-risk pathologic conditions. Scand J Gastroenterol 1994;29:1129-1134.

Background: Gastric cancer remains a major cause of mortality and will remain so for the lifetime of current clinicians. Many cancers are diagnosed at a stage when current therapy cannot provide the hope of cure. A method for early detection of gastric cancer which can be widely applied is needed. The serum levels of pepsinogen A and gastrin-17 have been shown to vary in the presence of pathologic conditions of the gastric mucosa and may provide such a tool.

Methods: Serum samples were obtained from 432 patients undergoing endoscopy for undiagnosed dyspepsia. The levels of pepsinogen I and gastrin-17 were estimated by radioimmunoassay and compared with the final diagnosis. Discriminant analysis was performed to assess the value of the the peptides predicting the presence of gastric cancer and the high-risk mucosal changes.

Results: Abnormal levels of gastrin-17 or pepsinogen A were found in 60% of patients with gastric cancer and 60% of those with one of the high-risk mucosal changes, the latter figure rising to 75% when the changes were in the upper third of the stomach. Discriminant analysis showed the log of gastrin-17 and log of pepsinogen A to be the best predictors of the high-risk mucosal changes, gastric cancer, and benign disease.

Conclusions: These results confirm gastrin-17 and pepsinogen A as markers of pathologic gastric conditions and suggest that these peptides are potential screening tools worthy of further assessment.     

Hypocalcemic effect of homologous angiotensin-like substances produced by the renin-like enzyme in the corpuscles of stannius in the Japanese eel Anguilla japonica

In the intact Japanese eel kept in fresh water, a homogenate of the corpuscles of Stannius (CS) from the carp produces hypocalcemia when 50 mg/kg body weight of the tissue is injected intraperitoneally each day for 3 days. Angiotensin-like substances formed by incubating the eel CS extract with homologous plasma are also hypocalcemic when 250 ng equivalent to [Asp¹, Ile⁵]angiotensin II per kilogram body weight is injected according to the above schedule. Angiotensin-like substances formed by incubating the eel kidney extract with homologous plasma are less hypocalcemic. CS, plasma, and unicubated controls for CS angiotensin preparation are not hypocalcemic. They are made by eliminating plasma, CS extract, or incubation from the incubation mixture, respectively. This indicates that only the incubation product of the CS extract with plasma is hypocalcemic. When the CS secretes renin-like enzyme into blood, the enzyme may produce angiotensin-like substances in vivo. Formed angiotensin-like substances may cause hypocalcemia. Therefore, the present results suggest that the renin-like enzyme in the CS may be identical to hypocalcin in the Japanese eel.     

Non-endoscopic diagnosis of multifocal atrophic gastritis; efficacy of serum gastrin-17, pepsinogens and Helicobacter pylori antibodies

BACKGROUND/AIMS: Infection with H. pylori is an important risk factor for the development of gastric cancer and glandular atrophy is an intermediate stage in gastric carcinogenesis. While screening the patients with atrophic gastritis by endoscopy is unrealistic, a concept of "serological gastric biopsy" based on measurement of gastric secretory proteins and peptides should be further validated. We sought to determine if the laboratory panel composed of serum PGI and protein stimulated gastrin-17 might select patients with MAG, and what is diagnostic significance of H. pylori serology in population of high prevalence of H. pylori infection. MATERIAL AND METHODS: 55 consecutive patients of both sexes (M/F 25/30; range of age 55 -81 years) were referred for gastroscopy with antrum and corpus mucosal biopsies. Patients with histological signs of glandular atrophy at any site of the stomach were considered to have multifocal atrophic gastritis. A first blood sample was collected for measurement of basal gastrin-17, pepsinogens and H. pylori IgG-antibodies, and second was taken 20 minutes after use of protein-rich drink to measure stimulated gastrin-17. RESULTS: Signs of mucosal atrophy were found in 19 patients, while 29 patients showed non-atrophic gastritis and seven H. pylori-negative patients had no histological pathology. Low serum level of stimulated gastrin-17 (< 5 pmol/l) and/or pepsinogen I (< 50 microg/l), were found in 16 of 19 patients (84.2%) with and in 7 of 36 patients (19.4%) without atrophy in the histological study. Combining of H. pylori serology with serum levels of secretory peptides had no significant effect on diagnostic sensitivity of the test panel. CONCLUSION: The test panel composed of pepsinogen I and protein stimulated gastrin-17 may be used as the "serological gastric biopsy" detecting multifocal atrophic gastritis. The diagnostic sensitivity of this test panel is not increased by knowledge of H. pylori status.     

Gastrin stimulates the self-replication rate of enterochromaffinlike cells in the rat stomach. Effects of omeprazole, ranitidine, and gastrin-17 in intact and antrectomized rats

The enterochromaffinlike cells in the rat stomach are rich in histamine and are thought to be under the influence of gastrin. The effect of sustained endogenous and exogenous hypergastrinemia on the activity and proliferation rate of the enterochromaffinlike cells was studied by determining the histidine decarboxylase activity and histamine concentration and by combining histamine immunocytochemistry and autoradiography after in vivo labeling with [3H]thymidine. The proliferation rate of the stem cells in the oxyntic mucosal progenitor zone was also studied. Exogenous hypergastrinemia was induced by infusion of rat gastrin-17 (60 nmol.kg-1.day-1). Endogenous hypergastrinemia was induced by inhibition of gastric acid secretion with omeprazole (80 mumol.kg-1.day-1) or ranitidine (1200 mumol.kg-1.day-1). The effect of omeprazole was also studied in antrectomized rats. In intact rats, all treatments resulted in elevated plasma gastrin levels and were accompanied by an increase in the histidine decarboxylase activity and the histamine content of the oxyntic mucosa. This resulted in an increase in the enterochromaffinlike cell proliferation rate, leading to enterochromaffinlike cell hyperplasia. The number of labeled stem cells was increased, but this effect was not as pronounced as in the enterochromaffinlike cells. In antrectomized rats, the inhibition of acid secretion by omeprazole did not result in elevated plasma gastrin or in an increase in the activity or number of enterochromaffinlike cells, indicating that omeprazole per se had no effect on these cells. These data support the view that gastrin stimulates the proliferation rate of both enterochromaffinlike cells and stem cells. Gastrin also stimulates the activity of the enterochromaffinlike cells.     

Species variation in the tyrosine sulfation of mammalian gastrins

The degree of tyrosine sulfation and the distribution between gastrin-17- and gastrin-34-like immunoreactivity (LI) were studied in the antra of ten mammalian species. Specific radioimmunoassays, gel-, and ion-exchange chromatography as well as enzymatic cleavage with trypsin and arylsulfatase were used. The percentage of sulfation varied from 24.4 +/- 4.2 (mean +/- SEM) in dogs to 80.1 +/- 2.6 in sheep, 46.8 +/- 3.3 in humans, 50.1 +/- 3.2 in cows, 55.9 +/- 2.3 in rats, 57.4 +/- 3.1 in pigs, 61.3 +/- 2.2 in guinea pigs, 64.1 +/- 4.7 in cats, 64.8 +/- 2.1 in mice and 68.2 +/- 2.8 in rabbits. Gastrin-34-LI in antral extracts could be converted to gastrin-17-LI by trypsin in all species. Five percent of antral gastrins eluted as gastrin-34-LI in all species. We conclude that while the ratio of gastrin-34-LI to gastrin-17-LI varies little in mammals, large differences occur in the degree of sulfation.     

Effect of chronic ethanol consumption on the response of parathyroid hormone to hypocalcemia in the pregnant rat

BACKGROUND: Chronic alcohol (ethanol) consumption during pregnancy results in maternal/fetal hypocalcemia, which may underlie some of ethanol's adverse effects on maternal and fetal bone, and fetal/neonatal health. Ethanol appears to alter the relationship between parathyroid hormone (PTH) and blood calcium (Ca) level, and PTH does not increase in response to ethanol-induced hypocalcemia. However, it is not known whether ethanol actually prevents PTH from responding, or whether the ability to regulate blood Ca is intact, but ethanol lowers the level of Ca maintained. The objective of this study was to determine whether chronic ethanol consumption impairs the ability of the pregnant female to increase PTH in response to acute hypocalcemia. METHODS: Rats were fed isocaloric diets with ethanol (36% ethanol-derived calories, E group) or without ethanol [pair-fed (PF) and control (C) groups], before and throughout 21 days of gestation. On day 21 gestation, rats received an intraperitoneal injection of ethylene glycol-bis (beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) (300 or 500 mumol/kg body weight) or saline (saline group), or no injection (baseline group). Blood was collected from the baseline group, and at 30 or 60 minutes postinjection (saline and EGTA groups), and analyzed for ionized Ca (iCa), pH, and PTH. RESULTS: Consistent with previous studies, ethanol consumption decreased blood iCa levels at baseline, but PTH levels did not differ among groups. Administration of EGTA significantly decreased blood iCa levels by 30 minutes, but ethanol did not prevent PTH from increasing in response to the hypocalcemia. In all diet groups, PTH levels were significantly increased by 30 minutes. Ethanol did, however, appear to decrease the maximum PTH level achievable in blood. CONCLUSIONS: These data suggest that chronic ethanol consumption does not impair the ability of the pregnant rat to raise serum PTH levels in response to acute hypocalcemia, but ethanol's effect on maximal PTH secretion could impair the ability of the pregnant female to sustain high PTH levels in response to chronic hypocalcemia.     

Effect of porcine calcitonin on the metabolism of calcium and cyclic AMP in rat skeletal tissue in vivo.

Infusion of 50 mU/100 g body wt of calcitonin induced a rapid and marked increase of cyclic AMP in calvaria as well as in plasma of thyroparathyroidectomized rats. These changes preceded the decrease in plasma calcium concentration seen after hormone administration. The possible relationship of this stimulation of cyclic AMP accumulation to the hypocalcemic effect of calcitonin was examined under several experimental settings. It was found that a dose of calcitonin sufficient to cause a significant decrease of plasma calcium failed to produce any detectable accumulation cyclic AMP in calvaria, but when high doses of calcitonin were given, there was an apparent correlation between the integrated change of cyclic AMP metabolism and the duration and magnitude of hypocalcemia. Experiments employing the ophylline and imidazole, which alter cyclic AMP metabolism, led to an apparent dissociation between the hypocalcemic effect of calcitonin and its stimulation of cyclic AMP accumulation in bone.     

The multifactorial basis for hypocalcemia during sepsis. Studies of the parathyroid hormone-vitamin D axis

To learn about the pathogenesis of sepsis-associated hypocalcemia, we measured serum ionized calcium concentrations in 60 critically ill patients with bacterial sepsis; 12 (20%) had hypocalcemia. The mortality rate in the hypocalcemic patients with sepsis (50%) was higher than that in the normocalcemic patients with sepsis (29%). Only patients with gram-negative sepsis became hypocalcemic, and hypocalcemia contributed to hypotension in 7 of the 12 hypocalcemic patients. Serum calcium concentrations returned to normal in each of those patients with sepsis who survived. Hypocalcemia during sepsis occurred in previously normocalcemic patients and was multifactorial in origin, resulting from acquired parathyroid gland insufficiency, renal 1 alpha-hydroxylase insufficiency, vitamin D deficiency, and acquired calcitriol resistance. We conclude that the hypocalcemia of sepsis is associated with a high mortality rate and usually occurs in previously normocalcemic patients who acquire a defect in the parathyroid-vitamin D axis.     

Effects of partial resection of acid-secreting mucosa on plasma gastrin and enterochromaffin-like cells in the rat stomach

Female rats were subjected to various degrees (50, 75, 90 and 100%) of fundectomy, i.e. resection of the acid-producing part of the stomach, to compare the effects of different degrees of reduction of the amount of acid reaching the antrum. Plasma gastrin was monitored for 10 weeks after the operation. Histidine decarboxylase (HDC) activity, histamine concentration and density of enterochromaffin-like (ECL) cells in the remaining oxyntic mucosa were determined in the rats subjected to 50 or 75% fundectomy. There was a close correlation between the amount of acid-producing mucosa removed and the plasma gastrin levels, the highest gastrin level being observed in the rats subjected to 100% fundectomy. HDC activity, histamine concentration and ECL cell density seemed to reflect plasma gastrin concentration. These findings indicate that hypergastrinemia induced by surgical removal of acid-producing mucosa in the rat has the same effects on oxyntical mucosal HDC activity, histamine concentration and ECL cell density as hypergastrinemia induced by continuous gastrin infusion or by long-term treatment with effective antisecretagogues.     

Distribution of serum calcium values in patients with familial benign hypercalcemia (hypocalciuric hypercalcemia): evidence for a discrete genetic defect

One group has reported hypocalcemic individuals in families affected with familial benign hypercalcemia (FBH), suggesting either that FBH is merely an extreme of normality or that hypocalcemia is independently inherited in that kindred. To test these hypotheses, we examined the distributions of serum total calcium (Ca) values in 260 normal adults and 171 adult individuals in 21 FBH kindreds. We excluded from analysis the 21 adult probands, leaving 85 apparently affected persons (Ca, greater than 10.1 mg/dL or greater than 2.52 mmol/L) and 65 apparently unaffected individuals (Ca, less than or equal to 10.1 mg/dL or less than or equal to 2.52 mmol/L). Five FBH family members were hypocalcemic (less than 8.9 mg/dL or less than 2.22 mmol/L); of these, 3 had hypoproteinemia or hypoalbuminemia, 1 had surgical hypoparathyroidism, and 1 was pregnant (and thus excluded from further analysis). Histogram analysis suggested a bimodal distribution of Ca in the FBH families, and familial serum Ca levels were significantly elevated (P less than 0.001, rank sum). When only apparently unaffected family members were compared with normal individuals with serum Ca of 10.1 mg/dL or 2.52 mmol/L or less, the distributions were virtually identical. Our results indicate that hypocalcemia in members of families with FBH is of sporadic nongenetic origin. Furthermore, FBH is not an extreme of the normal distribution, but, instead, a clear disturbance with its own distribution about a supranormal mean serum calcium value.     

Hemodialysis with calcium-free dialysate prevents myocardial creatine kinase depletion after brief coronary artery occlusion in dogs

To evaluate the effect of hypocalcemia on myocardial creatine kinase (CK) depletion after brief coronary artery occlusion and reperfusion, dogs were rendered hypocalcemic via systemic hemodialysis for eighty minutes in the absence of Ca. Control animals were hemodialysed in the presence of Ca. The left anterior descending coronary artery was then occluded for six minutes and reperfusion for eighty minutes occurred at low flow of dialysate. A 50% decrease in serum Ca of the hypocalcemic animals during the eighty minutes of hemodialysis resulted in a significant (about 35%) decrease of myocardial Ca. Comparison of the myocardial creatine kinase activity following reperfusion showed preservation of the enzyme in the ischemic areas of the hypocalcemic animals, whereas the CK activities of the ischemic areas of the normocalcemic animals were much lower (p less than 0.005). During the reperfusion period serum Ca of the hypocalcemic group increased to 75% of that of the normocalcemic group while myocardial Ca of both ischemic and nonischemic areas reequilibrated to normocalcemic values. Hemodynamic parameters during the various phases of the experiment were not altered significantly. It is concluded that transient decrease of myocardial Ca produced by hypocalcemia prior to occlusion leads to protection against myocardial damage after brief coronary ligation.     

Impaired parathyroid hormone response to hypocalcemic stimuli in a patient with hypomagnesemic hypocalcemia

Magnesium (Mg) deficiency sometimes causes hypocalcemia with impaired PTH secretion although the precise mechanism remains unclear. We examined the PTH secretion in response to physiological hypocalcemic stimuli in a patient with hypomagnesemic hypocalcemia. We adopted sodium bicarbonate infusion test, which we recently developed, to evaluate the PTH response to acute decrease in plasma ionized Ca. The results showed that, before Mg replacement and when the patient was mildly hypocalcemic, absolutely no PTH release to hypocalcemic stimuli was observed. In contrast, the plasma Ca was promptly normalized following the start of Mg replacement, and brisk PTH response to hypocalcemic stimuli was obtained during the same test carried out a week after the Mg replacement. The data in this case thus suggest that: a) the acute regulation of PTH release by plasma ionized Ca is lost in the patient with hypomagnesemic hypocalcemia, and b) Mg deficiency itself is likely to be a primary cause of this disorder because the hormone response was clearly restored after shortterm Mg replacement alone.     

Hypocalcemia. Differential diagnosis and mechanisms.

There is much individual variability in the clinical manifestations of hypocalcemia. The rapidly of the development of hypocalcemia will determine whether or not symptoms will be present. Signs and symptoms of hypocalcemia consisted of tetany (Chvostek's and Trousseau's signs), seizures, diminshed to absent deep tendon reflexes, papilledema, mental changes (weakness, fatigue, irritability, memory loss, confusion, delusion, hallucination), and skin changes. Etiologic factors for hypocalcemia in man include (1) decreased calcium absorption or increased loss from the gastrointestinal tract; (2) parathyroid hormone deficiency; (3) skeletal resistance to parathyroid hormone; (4) ineffective parathyroid hormone; (5) decreased production or increased degradation of 25-hydroxycholecalciferol or 1,25-dihydroxycholecalciferol; (6) increased complex formation with calcium; (7) increased skeletal uptake of calcium; (8) hypomagnesemic state; and (9) direct inhibition of bone resorption. Measurement of total and ionic calcium, magnesium, parathyroid hormone, vitamin D metabolites (25-hydroxycholecalciferol, 1,25-dihydroxycholecalciferol), and nephrogenous cyclic adenosine monophosphate are especially helpful in the laboratory evaluation of the hypocalcemic patient.     

Effects of calcium deficiency and calcium supplementation on gastrectomy-induced osteopenia in the young male rat

BACKGROUND: Surgical removal of the stomach (gastrectomy, Gx) induces osteopenia. In this study we compared the osteopenic effect of Gx with that induced by calcium (Ca) deficiency. METHODS: Young male rats were subjected to Gx and/or low Ca diet (-Ca). A group of Gx rats received standard diet + oral Ca supplementation (+Ca). The rats were killed at various times after the operation/start of treatment (longest time 12 weeks). After 8 weeks on low Ca diet, the blood Ca2+ concentration was lowered slightly in both Sham-operated and Gx rats. The calvariae were subjected to transillumination analysis and quantitative histomorphometry. Also the tibiae were subjected to histomorphometry. RESULTS: Transillumination of the calvariae revealed extensive bone loss in the rats that had been subjected to Gx and/or low Ca diet. Gx + Ca induced the same bone loss as Gx alone. These observations were later confirmed in quantitative terms by histomorphometry (Sham-Ca 56%, Gx 35%, Gx + Ca 32%, Gx - Ca 58% less bone area than in Sham). The osteopenia induced by Gx + low Ca diet seetned more rapid in onset than that induced by Gx or low Ca diet alone. Tibiae from Gx rats and rats given a low Ca diet displayed a reduced trabecular bone volume (Sham-Ca 27% remaining, Gx 36%, Gx + Ca 44%, Gx - Ca 17%) and reduced trabecular number (Sham-Ca 44% remaining, Gx 41%, Gx + Ca 56%, Gx - Ca 33%). The trabecular thickness was reduced in the Gx rats and Gx - Ca rats (Gx 78% remaining, Gx - Ca 63%) but not in Sham-operated rats receiving a low Ca-diet (95% remaining). CONCLUSION: Although the pattern of osteopenia was qualitatively quite similar in Gx rats and Ca-deficient rats, in quantitative terms the low Ca diet was more detrimental to bone than Gx. Ca deficiency induced a similar degree of osteopenia in both Sham and Gx rats. Ca supplementation failed to prevent the Gx-induced osteopenia.     

Calcium Supplement Increase on the Second Day of Sequential Two Day Leukapheresis

Abstract: Peripheral blood progenitor cells are collected effectively by leukapheresis of a large volume of peripheral blood. However, protection must be taken for patients or donors from hypocalcemia due to continuous infusion of citric acid. We found a tendency for hypocalcemic symptoms in patients or donors to occur more often on the second day than the first day of the sequential 2 days of leukapheresis. The doses of calcium gluconate supplement and the acid citrate dextrose‐A solution administration significantly increased on the second day compared to that of the first day. The blood levels of c‐terminal parathormone (PTH), phosphorus, and alkaline phosphatase did not show remarkably abnormal change. However, urine calcium excretion just after leukapheresis was higher than in the period before or after leukapheresis compared to the phosphorus or creatinine excretion. These findings indicate that the cause of a higher tendency to hypocalcemic symptoms on the second day of the sequential 2 days of leukapheresis is due to the higher metabolism of calcium being excreted in the urine during leukapheresis.