The response of circulating parameters of bone mineral metabolism to ethanol- and EDTA-induced hypocalcemia in the rat

The mechanism of the acute hypocalcemia that follows acute ethanol administration has not been established. Measurements of parathyroid hormone (PTH) performed during this hypocalcemia reveal conflicting results. We compared the response of ionized calcium (Ca2+), immunoreactive PTH and bone Gla protein (BGP) after ethanol- and EDTA-induced hypocalcemia. 103 male Sprague Dawley rats each weighing approximately 300 g received ethanol and 100 rats of similar weight received EDTA. In each of these studies the animals were divided into experimental and control groups. The ethanol-treated rats received ethanol, 2 g/kg body weight, by ip injection and the EDTA-treated rats received 100 mg EDTA/kg body weight by im injection. Controls received normal saline by the corresponding route of administration. Rats were sacrificed at 0, 30, 60, 90, 180 and 360 min for the measurement of the above parameters. In both experimental groups Ca2+ levels were significantly reduced to the same degree by 30 min with return to control values by 360 min. There was no significant difference in immunoreactive PTH, and BGP between control and ethanol-treated groups. In the EDTA-treated rats, however, PTH values were significantly increased at 30 (P less than 0.005) and BGP at 60 and 90 minutes (P less than 0.005) vs. control. Therefore acute ethanol administration appears to blunt the PTH response to hypocalcemia. A direct inhibitory effect of ethanol on osteoblast function ie BGP production cannot be excluded. In addition, PTH may stimulate BGP.

The bisphosphonate 2-PEBP inhibits cyclosporin A induced high-turnover osteopenia in the rat

A bisphosphonate, 2-PEBP (2-(2-pyridinyl) ethylidene bisphosphonate), was administered to animals receiving cyclosporin A (CsA) in an attempt to modify the high-turnover osteopenia associated with CsA therapy. Four groups of female Sprague-Dawley rats were administered either vehicle or CsA (15 mg/kg per day) by gavage for 28 days, together with either normal saline solution or 2-PEBP (1.72 mg/kg per day) given by intraperitoneal injection on days 0,1, and 2. The groups thus comprised Group A, vehicle/normal saline; group B, vehicle/2-PEBP; group C, CsA/normal saline solution; group D, CsA/2-PEBP. All rats received tetracycline hydrochloride by intraperitoneal injection for histomorphometric labeling. Blood was sampled on days 0, 7, 14, 21, and 28 for ionized calcium, serum phosphate, parathyroid hormone (PTH), 1,25-dihydroxyvitamin D (1,25(OH)2D), blood urea nitrogen (BUN), creatinine, magnesium, and bone gla protein (BGP). Rats were killed on day 28 for tibial bone histomorphometry. All results were compared with group A. There were no significant differences in weight, ionized calcium, PTH, and serum phosphate between groups. Weight increased significantly by day 28 in all groups. Groups C and D revealed significantly higher levels of 1,25(OH)2D, BUN, and creatinine on days 14 and 28. Magnesium was significantly lower in groups C and D on days 14 and 28. BGP increased significantly in group C and decreased significantly in group B during the study. Tibial bone histomorphometry revealed high-turnover osteopenia in group C, significant improvement in both bone formation and resorption parameters in group D and hyperostosis in group B. Serum BGP reflected the histomorphometric indices of bone formation in each group.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of high-dose salmon calcitonin on bone mineral metabolism in the normal rat

The paucity of information on the effect of long-term high-dose salmon calcitonin administration on normal bone mineral metabolism and histology prompted an investigation of the influence of high-dose synthetic calcitonin in the rat. Serum ionized calcium, osteocalcin or BGP (bone gla protein), and immunoreactive PTH were measured serially during calcitonin administration and bone histomorphometry analyzed at 6 weeks (after sacrifice). Daily injections of salmon calcitonin, 0.4 IU/100 g (group B) and 2 IU/100 g (group C), resulted in significant hypocalcemia at 4 hours for both experimental groups (P less than 0.004). Serum iPTH was significantly higher over the study period for both groups administered calcitonin. Serum BGP levels were significantly lower than controls during the study in group C (P less than 0.002) and to a lesser extent in group B (P less than 0.05). In group C, bone histomorphometry revealed increased resorption (osteoclast count), decreased trabecular bone volume, and decreased double-labeled tetracycline surface (bone formation). In group B an increase in osteoclast count but no alteration in bone formation was observed. To assess the role of PTH in the above findings, high-dose calcitonin was administered to parathyroidectomized rats. All of the above changes in bone histomorphometry were not observed in this group of animals. In conclusion, high doses of calcitonin promote hypocalcemia, secondary hyperparathyroidism, and osteoclastosis in the normal rat in a dose-dependent manner with very high-dose calcitonin impairing bone formation.

Alteration of vitamin D metabolism in Mexican-Americans

Studies were performed to investigate vitamin D metabolism in Mexican-Americans. Groups of 15 whites and 16 Mexican-Americans ranging in age from 18 to 41 years were evaluated. All of them were within 25% of their ideal body weight. Each of them was admitted to the Clinical Research Center of the University of Texas Health Science Center and placed on a daily diet estimated to contain 400 mg calcium and 900 mg phosphate. It was found that whereas serum vitamin D (1.8 +/- 0.5 versus 7.6 +/- 1.3 ng/ml, P less than 0.001) and serum 25-hydroxyvitamin D (9 +/- 1 versus 17 +/- 2 ng/ml, P less than 0.01) were significantly lower and serum 1,25-dihydroxyvitamin D (37 +/- 2 versus 28 +/- 2 pg/ml, P less than 0.001) was significantly higher in the Mexican-Americans than in the whites, serum calcium (9.1 +/- 0.1 versus 9.2 +/- 0.1 mg/dl), magnesium (1.84 +/- 0.07 versus 1.80 +/- 0.07 mEq/liter), and Gla protein (19 +/- 3 versus 21 +/- 2 ng/ml) were not different in the two groups. Urinary calcium (144 +/- 14 versus 124 +/- 16 mg/day), phosphate (672 +/- 51 versus 683 +/- 44 mg/day), sodium (110 +/- 8 versus 99 +/- 9 mEq/day), potassium (43 +/- 4 versus 49 +/- 3 mEq/day), and magnesium (7.3 +/- 0.7 versus 7.7 +/- 0.5 mEq/day) and creatinine clearance (173 +/- 14 versus 154 +/- 7 liters/day) were not different in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Modulation of arachidonic acid metabolism has limited effects on the development of type I diabetes in animal models

The therapeutic potential of modulators of arachidonic acid metabolism was probed in two animal models of type I (insulin-dependent) diabetes. Sulphasalazine treatment (50 and 400 mg/kg) did not affect diabetes development in the low dose streptozotocin model in male CD-1 mice nor in diabetes prone BB/WorD rats (100 mg/kg). Administration of acetyl salicylic acid (50 mg/kg) or BW755C (60 mg/kg) caused partial suppression of hyperglycaemia in male C57BL/6 mice after low dose streptozotocin. Twice daily treatment of BB rats with acetyl salicylic acid (5 mg/kg) did not significantly alter the course of diabetes development. We conclude that modulation of arachidonic acid metabolism has limited effects on immune-mediated diabetes.

Sensorineural hearing loss

The authors emphasize the importance of early identification and early intervention concerning the management of children with Sensorineural Hearing Loss. The pediatrician plays a critical role in initiating the necessary clinical and audiological evaluations. Guidelines and treatment options are reviewed.

Bone-derived proteins

The diagnosis and treatment of metabolic bone disease has been limited by a lack of understanding of bone cell physiology and of suitable markers for various bone cell functions in different diseases. The identification of noncollagenous proteins and their measurement in serum has added to our knowledge. At this stage, of all the bone-derived proteins, bone Gla protein (BGP) is apparently the most useful, but it is best used in conjunction with other tests. The diagnostic usefulness of other noncollagenous proteins, procollagen, and local factors still remains to be documented.

Constructive thinking: a broad coping variable with specific components

The structure of constructive thinking and the development of an instrument for measuring it, the Constructive Thinking Inventory (CTI), were discussed. Scales were derived from a factor analysis of an item domain of people's everyday automatic thinking. When the CTI and other tests were factor analyzed, separate intellective and nonintellective factors were found, with the CTI loading more strongly on the nonintellective factor than any other test. Only measures of IQ loaded on the intellective factor. The global constructive thinking scale correlated significantly with success in work, love, social relationships, and in maintaining emotional and physical well-being, but not with academic achievement, the only criterion with which the measures of IQ correlated strongly. The patterns of correlations between the CTI scales and the various criteria as well as the factor analysis demonstrated that the construct of constructive thinking is differentiated as well as integrated.

Changes in breath 13CO2/12CO2 consequent to exercise and hypoxia

Page 936: T. J. Barstow, D. M. Cooper, S. Epstein, and K. Wasserman. “Changes in breath 13CO2/12CO2 consequent to exercise and hypoxia.” Page 936, right column, sentence beginning on line 8 should read: We therefore wondered if changes in EN could be used to detect changes in endogenous substrate oxidation during exercise. Page 940, right column, sentence beginning on line 15 should read: We controlled for potential acute modulators of oxidative fuel mix (e.g., meal and activity) by the overnight fast and avoidance of strenuous activity 24 h before each test. Page 941, left column, sentence beginning on line 27 should read: In summary, Vo2 adjusts slightly more rapidly than Vco2 in the transition from rest to exercise, whereas 13CO2 adjusts much more slowly. Page 938, Table 3 footnote should read:

Values are group means for individual responses averaged from 5 to 20 min of exercise. n = 7 except for WR-3 where n = 6. Hypoxia represented FiO02, = 0.15, room air FiOO2, = 0.207. *Significantly di fferent from both WR-1 conditions and WR-2 in room air (P < 0.05). Note that work above LT (WR-2 in hypoxia and WR-3) resulted in a significant increase in R.

Changes in breath 13CO2/12CO2 consequent to exercise and hypoxia

Page 936: T. J. Barstow, D. M. Cooper, S. Epstein, and K. Wasserman. “Changes in breath 13CO2/12CO2, consequent to exercise and hypoxia.” Page 936, right column, sentence beginning on line 8 should read: We therefore wondered if changes in EN could be used to detect changes in endogenous substrate oxidation during exercise. Page 940, right column, sentence beginning on line 15 should read: We controlled for potential acute modulators of oxidative fuel mix (e.g., meal and activity) by the overnight fast and avoidance of strenuous activity 24 h before each test. Page 941, left column, sentence beginning on line 27 should read: In summary, Vo2, adjusts slightly more rapidly than Vo2 in the transition from rest to exercise, whereas 13CO2 adjusts much more slowly. Page 938, Table 3 footnote should read:

Values are group means for individual responses averaged from 5 to 20 min of exercise. n = 7 except for WR-3 where n = 6. Hypoxia represented FiO02 = 0.15, room air Fioo2 = 0.207. * Significantly different from both WR-1 conditions and WR-2 in room air (P < 0.05). Note that work above LT (WR-2 in hypoxia and WR-3) resulted in a significant increase in R.

Serum osteocalcin and bone mineral metabolism following successful renal transplantation

Serum osteocalcin (bone gla protein, BGP), a vitamin K-dependent non-collagenous bone protein and its relationship to other markers of bone and mineral metabolism were studied cross-sectionally in varying numbers of patients before and over 240 days following renal transplantation. Marked elevation of serum creatinine (11.9 +/- 0.76 mg/dl), osteocalcin (216.9 +/- 7 ng/ml), parathyroid hormone (PTH, mid-molecule fragment) (24.5 +/- 3.6 ng/ml), alkaline phosphatase (255.2 +/- 54.7 IU/l) and phosphorus (5.6 +/- 0.3 mg/dl) were noted preoperatively. Serum calcium levels remained normal throughout the study period while phosphate levels normalized within one week after transplantation. PTH levels progressively decreased postoperatively over the study period but were still elevated well above normal. Serum osteocalcin decreased to near normal values at 60-90 days after surgery. Both PTH and alkaline phosphatase correlated significantly with osteocalcin preoperatively and postoperatively. The relatively depressed values of osteocalcin in the face of still elevated PTH levels post-transplantation was attributed to the effect of immunosuppressive corticosteroid therapy. The significant correlation between PTH and osteocalcin suggests that osteocalcin may be as or more sensitive a measurement of bone turnover than alkaline phosphatase pre- and post-transplantation.

Cyclosporin A in the oophorectomized rat: unexpected severe bone resorption

Local factors, such as interleukin-1, may mediate the accelerated bone remodeling in the acute estrogen-deficient rat. Cyclosporin A (CsA), which in vitro inhibits some of these local factors, was administered to oophorectomized (OX) rats in an attempt to modify this high turnover state. Three groups of 15 rats were studied. Group A was sham operated, group B was OX, and group C was OX and received CsA (15 mg/kg per day) by gavage commencing 4 days postoophorectomy for 28 days. Estradiol levels were determined to confirm oophorectomy. Blood was sampled on days -7, 0, 7, 14, 21, and 28 for ionized calcium (Ca2+), 1,25-(OH)2-vitamin D, PTH, and bone gla protein (BGP). Rats received tetracycline hydrochloride for bone histomorphometric labeling. All results were compared to group A. Body weight was increased in group B (p less than 0.003) but not in group C. There was no difference in Ca2+ or PTH between the groups. BGP levels were higher in group B by day 28 (p less than 0.005); BGP levels were increased in group C from days 7-28 (p less than 0.002). 1,25-(OH)2-vitamin D was significantly increased in group C (p less than 0.0001) but not in group B. Tibial bone histomorphometry revealed increased measurements of bone formation and osteoclast number without a loss of bone volume (BV/TV) in group B. Group C showed a dramatic increase in bone turnover with significant loss of BV/TV (p less than 0.001). In conclusion, CsA in the OX rat resulted in unexpected enhanced bone remodeling with high BGP levels and severe bone resorption.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of cyclosporin A administration and its withdrawal on bone mineral metabolism in the rat

The in vivo administration of cyclosporin A (CsA) has been associated with significant bone loss and increased bone remodeling. To observe whether these changes are reversible, we have investigated the consequences of the administration and withdrawal of CsA immunotherapy on bone mineral metabolism. Three groups of Sprague-Dawley rats were studied for 28 days. Group A received vehicle, and group B received CsA (15 mg/kg BW) for 28 days, while group C received CsA (15 mg/kg BW) for 14 days and then vehicle from days 15-28 by daily gavage. Serum ionized calcium (Ca2+), PTH, bone gla protein, blood urea nitrogen, creatinine, magnesium, phosphorus, and 1.25-dihydroxyvitamin D were measured weekly. Bone histomorphometry was analyzed on days 14 and 28 in groups A and B and on day 28 in group C. CsA administration resulted in reversible hypomagnesemia and mild transient elevation in circulating 1,25-dihydroxyvitamin D levels with no change in Ca2+, PTH, blood urea nitrogen, or phosphorus. Serum bone gla protein levels were significantly increased (P less than 0.002) during CsA therapy, but tended to return to control values after CsA withdrawal. Enhanced bone remodeling and significant trabecular bone loss accompanied CsA administration. Withdrawal of CsA resulted in all of the histomorphometric parameters, except for bone volume, returning to control values within 2 weeks. Incomplete restoration of bone volume occurred 5 weeks after CsA withdrawal. This limited restoration of bone volume despite CsA withdrawal may have important clinical implications.

Changes in breath 13CO2/12CO2 consequent to exercise and hypoxia

Because the natural enrichment of carbohydrate with 13C is greater than that of lipid, we hypothesized that the natural enrichment of exhaled CO2 with 13C (EN) could be used to gauge endogenous substrate utilization in exercising human subjects. To test this, EN and the respiratory exchange ratio (R) which equals the respiratory quotient (RQ) in the steady state, were measured simultaneously in seven subjects. Rest and exercise protocols, performed under conditions of room air (sea level) and hypoxic (inspired O2 fraction = 0.15) breathing, were chosen to cause a variety of patterns of oxidative substrate utilization. Work rates were performed both below and above the subject's lactate threshold (LT). Work above the LT was expected to cause the greatest increase in EN reflecting greater utilization of glucose. There was significant intersubject (P less than 0.05) but not intrasubject variability in resting EN. By 40 min of exercise, EN increased significantly (P less than 0.05) over resting values in all exercise protocols during both room air and hypoxia conditions. In the room air studies, we found no difference in EN during the below-LT work, even though there were significant increases in O2 uptake (VO2). In contrast, above-LT work resulted in significantly greater increases in EN by 20 and 40 min of exercise (P less than 0.05). Contrary to our expectations, we observed no separate effect by hypoxia on the EN during exercise. Both EN and R tended to increase from rest to exercise, but during exercise there was no overall correlation between R and the EN. EN reflects changes in endogenous substrate utilization over relatively long periods of time such as at rest, but delays in the appearance of 13CO2 at the mouth due to dilution in body CO2 pools, and possibly isotopic fractionation, preclude the usefulness of EN as an indicator of endogenous fuel mix during short-term exercise.

Constructive thinking: A broad coping variable with specific components

The structure of constructive thinking and the development of an instrument for measuring it, the Constructive Thinking Inventory (CTI), were discussed. Scales were derived from a factor analysis of an item domain of people's everyday automatic thinking. When the CTI and other tests were factor analyzed, separate intellective and nonintellective factors were found, with the CTI loading more strongly on the nonintellective factor than any other test. Only measures of IQ loaded on the intellective factor. The global constructive thinking scale correlated significantly with success in work, love, social relationships, and in maintaining emotional and physical well-being, but not with academic achievement, the only criterion with which the measures of IQ correlated strongly. The patterns of correlations between the CTI scales and the various criteria as well as the factor analysis demonstrated that the construct of constructive thinking is differentiated as well as integrated.

Carbamazepine-induced reduction of plasma alprazolam concentrations: a clinical case report

A patient with atypical bipolar disorder and panic attacks treated with alprazolam 7.5 mg/day showed a greater than 50% reduction in plasma alprazolam concentrations after carbamazepine treatment was initiated and experienced a corresponding clinical deterioration. Clinical and plasma concentration data are presented.

The effect of chronic caffeine administration on serum markers of bone mineral metabolism and bone histomorphometry in the rat

Caffeine has been cited as a risk factor for osteoporosis in humans. In rats, caffeine increases calcium absorption and excretion and raises parathyroid hormone (iPTH) levels. This study investigated the effect of chronic caffeine administration on bone histomorphometry and serum markers of bone mineral metabolism. Twenty-seven male Sprague Dawley rats weighing approximately 300 g were divided into three groups: Group A (n = 8) served as controls, Group B (n = 9) received 2.5 mg/100 g caffeine in their drinking water, and Group C (n = 10) received 10 mg/100 g body weight caffeine in their drinking water. Animals were bled serially for the 8 week study period: Ionized calcium was measured from tail vein blood and serum iPTH and osteocalcin (BGP) from orbital sinus blood. All three groups received two doses of tetracycline for bone histomorphometry which was performed on a right tibial section from each animal. Ionized calcium was not different among the three groups at any time point. No alteration in serum iPTH levels was demonstrated except for day 56 when the high-dose group (C) showed a raised level (mean = 59.1, SE = +/- 8.9 pg/ml (P less than 0.05). By week 8 Group C showed a failure to gain weight compared with Group A. Group C mean weight = 384.0 +/- 6.6 g, Group A 427.4 +/- 10.8 g (P less than 0.005). Serum BGP was significantly increased in Group C compared with control (P less than 0.001). No differences in bone histomorphometry were observed among the three groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum and urinary markers of bone remodeling: assessment of bone turnover

It appears that at present, serum BGP is the one bone protein that has the most promise for assisting in the diagnosis and management of high turnover metabolic bone disease states. If further studies confirm its usefulness in osteoporosis as a predictor of rapid bone loss without the need for bone biopsy, this serum marker will then not only allow early detection but also an appropriate choice of therapy in osteoporosis, i.e. the use of specific inhibitors of high turnover states such as estrogen, calcitonin, or bisphosphonates. In addition, it may also permit more accurate follow-up of patients suffering from diseases such as primary hyperparathyroidism after surgery. In low turnover osteoporosis, it may also serve a useful function to observe whether the osteoblast can be stimulated to enhance bone formation with therapies such as fluoride, anabolic steroids, PTH, etc. As yet, additional measurements, such as bone histomorphometry and other bone mineral markers, are required for definitive diagnosis. Hopefully, the availability of specific well-characterized antibodies against BGP may define its role more accurately. Recently, several other new bone proteins have been identified but at present they have very limited clinical application. Future studies into the structure-function relationship of these bone proteins may identify those markers which will be most relevant to the diagnosis and treatment of metabolic bone disease.

Cyclosporin-A in vivo produces severe osteopenia in the rat: effect of dose and duration of administration

Cyclosporin-A (CsA) inhibits the in vitro bone-resorbing effects of cytokines. We investigated the in vivo effects of CsA on rat bone mineral metabolism. Three groups of male Sprague-Dawley rats were administered vehicle or low dose (7.5 mg/kg) or high dose (15 mg/kg) CsA for 14 and 28 days. Ionized calcium, PTH, serum bone Gla protein, blood urea nitrogen, creatinine, magnesium, and 1,25-dihydroxyvitamin D were determined serially. No significant changes in calciotropic hormones or renal function were noted. Significant bone resorption and trabecular bone loss occurred in the high dose group by day 14 and in both groups by day 28. Bone Gla protein was significantly increased within 2 weeks in both dosage groups (P less than 0.005), reflecting increased bone remodeling. CsA in vivo resulted in an unexpected and significant increase in bone remodeling, with striking bone loss. These effects are dependent on the duration and dose of CsA and appear to be mediated at a local level.

Normal vitamin D and mineral metabolism in essential hypertension

The effects of dietary sodium upon serum and urinary calcium and selected vitamin D metabolites were studied in two groups (n = 10 each) of age and gender matched, white normotensive subjects and patients with normal-renin hypertension. Isocaloric diets were consumed on a metabolic ward with sequential daily sodium intake of 109 meq for 5 days and 9 meq and 259 meq for 6 days each. Values for serum and urinary calcium, phosphorus, magnesium and electrolytes, creatinine clearance, plasma immunoreactive parathyroid hormone, and serum 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D were similar in both study groups on each diet. Measurements of plasma renin activity and serum aldosterone levels were higher in the hypertensive than in the normotensive group on each diet (p less than .05-.01). Serum 1,25-dihydroxyvitamin D and urinary calcium increased on the high sodium diet in the normotensive (p less than .05) and the hypertensive groups (p less than .01). When the data for normotensive subjects and hypertensive patients were pooled by gender, males had a 1 1/2 to 3 times the urinary calcium excretion than females, regardless of diet. The present study indicates that there are no differences in the selected components of calcium and vitamin D metabolism in response to sodium intake in patients with essential hypertension and normal plasma renin activity as compared to normal controls.

Evidence of a probable role for 25-hydroxyvitamin D in the regulation of human calcium metabolism

1,25-Dihydroxyvitamin D [1,25-(OH)2D] is the principal mediator of the biologic effects of vitamin D. We showed previously that obese white subjects have low serum vitamin D and 25-hydroxyvitamin D (25-OHD) with increased serum-immunoreactive parathyroid hormone (PTH) and 1,25-(OH)2D, low urinary calcium, and increased urinary cyclic adenosine 3',5'-monophosphate (cyclic AMP) compared with nonobese white individuals. To determine whether 25-OHD modulates calcium metabolism, the effects of 25-OHD3, 40-100 micrograms/day for 9 days, were compared in seven obese and seven nonobese white subjects who were between the ages of 20 and 34 years. Each of them was hospitalized on a metabolic ward and given a constant daily diet that contained 400 mg calcium, 900 mg phosphate, and 18 mEq magnesium. Whereas 25-OHD3 increased mean serum 25-OHD from 7 +/- 1 to 37 +/- 5 ng/ml (P less than 0.01) and urinary calcium from 102 +/- 18 to 146 +/- 17 mg/day (P less than 0.001) and decreased mean serum 1,25-(OH)2D from 40 +/- 2 to 28 +/- 2 pg/ml (P less than 0.01) and urinary cyclic AMP from 3.23 +/- 0.57 to 2.00 +/- 0.17 nM/dl GF (P less than 0.05), it did not change mean serum calcium, ionized calcium, phosphate, magnesium, immunoreactive PTH or urinary phosphate, or creatinine clearance in the obese subjects. In contrast, 25-OHD3 increased mean serum 25-OHD from 16 +/- 1 to 46 +/- 4 pg/ml (P less than 0.001) but did not alter mean serum 1,25-(OH)2D or urinary calcium or cyclic AMP in the nonobese subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of muscle-building exercise on vitamin D and mineral metabolism

Exercise and muscle strength are important determinants of bone mass. Studies were carried out in normal young adult white males to determine the effects of exercise on vitamin D and mineral metabolism. Fourteen men who had engaged in regular muscle-building exercises for at least 1 year and 14 age-matched controls (age range, 19-36 year) were hospitalized on a metabolic ward and were given a constant daily diet estimated to contain 400 mg of calcium, 900 mg of phosphorus, 110 mEq of sodium, 65 mEq of potassium, and 18 mEq of magnesium. Body weight averaged 78 +/- 3 kg in the exercisers and 72 +/- 2 kg in the controls (NS). Serum calcium, ionized calcium, phosphate, magnesium, somatomedin-C, and immunoreactive parathyroid hormone (PTH) were not different in the two groups, whereas serum Gla-protein (39 +/- 5 vs. 24 +/- 2 ng/ml, p less than 0.01), 25-hydroxyvitamin D (23 +/- 2 vs. 16 +/- 2, p less than 0.05) and 1,25-dihydroxyvitamin D [1,25(OH)2D] (40 +/- 2 vs. 29 +/- 2 pg/ml, p less than 0.01) were higher in the exercisers than in the controls. Urinary calcium, phosphorus, sodium, potassium, creatinine clearance, and norepinephrine were not different in the two groups, whereas urinary magnesium (12.6 +/- 1.0 vs. 9.4 +/- 0.5 mEq/d, p less than 0.01) and urinary cyclic adenosine 3',5'-monophosphate (cyclic AMP) (2.52 +/- 0.19 vs. 1.72 +/- 0.20 nM/dl glomerular filtrate, p less than 0.01) were higher in the exercisers than in the controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Creatine kinase elevation after neuroleptic treatment

Two cases of asymptomatic elevation of creatine kinase levels after oral neuroleptic treatment are described. One patient was successfully challenged with a different neuroleptic. The authors discuss possible reasons for creatine kinase elevation.

Bone mineral metabolism in experimental diabetes mellitus: osteocalcin as a measure of bone remodeling

The etiology of diabetic osteopenia has not been established. The value of serum osteocalcin (BGP) as a marker of the bone abnormalities and the possible role of the polyol pathway in diabetic osteopenia were investigated. Three groups of rats were studied over 7 weeks: group D (n = 12), rats with streptozotocin (55 mg/kg)-induced diabetes given saline by gavage; group DS (n = 12), rats with streptozotocin-induced diabetes given the aldose reductase inhibitor sorbinil (25 mg/kg) daily by gavage; and group C (n = 6), saline-injected controls. Circulating levels of ionized calcium, BGP, amino-terminal PTH, and glucose were measured on days 0, 7, 14, 28, and 49. Tibial bone specimens were examined for the presence of aldose reductase by immunocytochemistry and by histomorphometry after tetracycline labeling. Diabetic rats with or without sorbinil treatment failed to gain weight [group D, 234 +/- 26 g; group DS, 217.0 +/- 40 g; group C, 310 +/- 33 g (mean +/- SD)]. Serum BGP levels decreased significantly in the diabetic rats within 7 days and remained lower throughout the study. BGP values on day 7 were: group D, 47.7 +/- 4.9 ng/ml; group DS, 65.9 +/- 5.5 ng/ml; and group C, 90.4 +/- 4 ng/ml (mean +/- SEM). Serum PTH levels were similar in all groups, except for day 49, when an increase in the D group was observed. Bone histomorphometry showed decreased bone remodeling in the D group, which confirmed the serum BGP findings. Aldose reductase was detectable in the small blood vessels and in bone itself. Sorbinil failed to influence the biochemical or bone histomorphometric abnormalities associated with diabetes. Serum BGP may be a valuable marker for the decreased bone remodeling in insulinopenic diabetes.

Demonstration of reduced mitogenic and osteoinductive activities in demineralized allogeneic bone matrix from vitamin D-deficient rats

Osteoinduction is the formation of ectopic bone that follows implantation of demineralized allogeneic bone matrix (DABM) and is believed to be secondary to the release of associated inductive factors from bone matrix. To clarify the role of vitamin D in osteoinduction, we implanted DABM from vitamin D-deficient rats (-D rats) into normal rats (+D rats). Because mitogens and osteocalcin might be involved in osteoinduction, these were measured. Mitogenic activity in extracts from mineralized allogeneic bone matrix (ABM) and DABM from both +D and -D rats was determined with an assay that utilizes monolayer cultures of embryonic chick calvarial cells. Osteocalcin in serum and DABM was measured by radioimmunoassay. DABM from -D rats did not promote osteoinduction as effectively as DABM from +D rats. Resorption of implant matrix from -D rats was diminished compared with resorption of matrix from +D rats (P less than 0.01), and the decrease was attributed to a corresponding decrease in the number of osteoclasts in the implants (P less than 0.02). Bone formation (P less than 0.01) and total implant mineralization (P less than 0.001) were significantly reduced in implants from -D rats, and the reductions corresponded with a decline in the number of osteoblasts (P less than 0.05). Mitogenic activity in DABM from +D rats was only slightly decreased as compared with activity in ABM, but DABM from -D rats contained significantly less activity (P less than 0.001). No mitogenic activity was identified in implants of DABM from either +D or -D rats 3 wk after implantation. Serum osteocalcin was significantly higher in -D as compared with +D animals. In contrast, the concentrations of osteocalcin in DABM from the two groups of animals were not significantly different from each other. These findings indicate that the diminished osteoinductive activity of DABM from -D rats results from deficiency of one or more mitogenic factors that are essential for inducing the proliferation and differentiation of bone cells at the implant site and that osteocalcin does not play a role in this regard.

S-process krypton of variable isotopic composition in the Murchison meteorite

Current theories on the origin of the chemical elements explain the abundance of medium-heavy and heavy nuclides to be due to the capture by pre-existing lighter nuclides of free neutrons on either a slow timescale (s-process) or a rapid timescale (r-process). Experimental evidence in support of these theories comes from the analysis of carbonaceous chondrites. In acid-resistant residues of these meteorites a kind of xenon has been found, the isotopic composition of which matches almost perfectly that predicted for s-process xenon. We report data that allow us, for the first time, to derive with reasonable precision the full isotopic spectrum of s-process krypton as well. We show that this s-Kr in a residue from Murchison meteorite did not originate in one single s-process but rather is a mixture of contributions from stellar environments where the density of free neutrons was not the same. The astrophysical conditions under which this Krypton has been produced were distinct from those that have been invoked to explain the Solar System s-process abundance. Similar to the 13C-rich carbon component in an aliquot of the same residue, the s-process Kr from different astrophysical sites has retained its identity during the accumulation and subsequent history of the meteorite.

Long term administration of prostaglandin inhibitors in vivo fail to influence cartilage and bone mineral metabolism in the rat

Non-steroidal anti-inflammatory drugs are potent inhibitors of prostaglandin synthesis. Prostaglandins have been reported to stimulate bone resorption and to enhance 1,25(OH)2D3 production in vitro. In patients with osteoarthritis of the hip, non-steroidal anti-inflammatory drugs are associated with localized accelerated bone destruction. The mechanisms for some of the in vivo effects are unknown. The effects of prostaglandin inhibitors on normal bone and mineral homeostasis has not been established. Therefore 15 male Sprague-Dawley rats were given daily injections of indomethacin, 2 mg/kg s.c., for either 4 or 8 weeks (a dose known to inhibit fracture healing) and compared to 13 control rats given vehicle alone. Serum Ca, BGP and 1,25(OH)2D were measured serially until day 56 in nine of those administered indomethacin and in seven of the control animals. Bone histomorphometry with double tetracycline labelling and cartilage histology were performed after sacrifice on days 28 and 56. Compared to control animals serum ionized calcium, BGP and 1,25(OH)2D levels were not altered by indomethacin administration. Quantitative histomorphometric indices of bone formation and resorption as well as cartilage histology were not significantly different between the two groups. With time, however, serum bone Gla protein fell in the control and indomethacin-treated groups, while calcium and 1,25-dihydroxyvitamin D remained stable. The age related decline in this serum marker of bone turnover was accompanied by a parallel reduction in the level of bone remodelling activity. These reductions in bone formation and bone resorption were not retarded or enhanced by indomethacin.(ABSTRACT TRUNCATED AT 250 WORDS)

Oxygen and carbon isotopic compositions of gases respired by humans

Oxygen-isotope fractionation associated with respiration in human individuals at rest is linearly related to the fraction of the O2 utilized in the respiration process. The slope of this relationship is affected by a history of smoking, by vigorous exercise, and by the N2/O2 ratio of the inhaled gas. For patients who suffer anemia-related diseases, the slope of this relationship is directly proportional to their level of hemoglobin. These results introduce a new approach for studying the mechanisms of O2 consumption in human respiration and how they are affected by related diseases.

Serum bone gla protein and the vitamin D endocrine system in the oophorectomized rat

Because of the importance of estrogen in osteoporosis, the effects of decreased estrogen production using sensitive measurements of bone mineral metabolism were studied in oophorectomized rats. Serum levels of ionized calcium, bone gla protein (BGP), vitamin D metabolites (25-hydroxyvitamin D and 1,25-dihydroxyvitamin D), and estradiol were measured before and serially for 6 weeks after oophorectomy in the rat. In addition, static and dynamic indices of bone histomorphometry were determined after double tetracycline labeling. Fifty Sprague-Dawley female rats (approximately 250 g) were studied. Twenty-five rats underwent oophorectomy (O), while the remaining rats were sham operated. Estrogen deficiency was noted in the O group within a week after surgery (estradiol, 2.45 +/- 0.78 vs. 27.9 +/- 4.15 pg/ml; P less than 0.05). Serum ionized calcium levels, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, and PTH levels did not differ between the two groups during the length of the study. Serum BGP levels were the same in both groups until the second week postoophorectomy, after which BGP remained significantly elevated in the O animals (121.7 +/- 5.95 vs. 76.7 +/- 3.87; P less than 0.001). Bone histomorphometry revealed increased osteoid volume (4.4 +/- 0.9% vs. 2.3 +/- 0.7%), osteoblast surface (26.5 +/- 2.4% vs. 3.2 +/- 1.2%), tetracycline surface (18.9 +/- 4.1% vs. 6.8 +/- 2.2%), as well as osteoclast surface (8.2 +/- 1.4% vs. 2.5 +/- 2%) in all O animals compared with those in the sham-operated group. These data indicate that oophorectomy and decreased estrogen result in increased bone turnover with elevated BGP levels. The marked BGP elevation within 2 weeks postoophorectomy suggests that estrogen withdrawal results in rapid altered bone mineral metabolism. The lack of concomitant increase in circulating PTH levels suggests that other factors may be mediating the bone loss following surgical oophorectomy.

Alteration in osteoblast activity and nutritional vitamin-D deficiency in non-hypercalcemic malignancy

The biochemical parameters of bone mineral metabolism in patients with nonhypercalcemic malignancy have not been extensively investigated. Therefore, a group of 29 such patients with different types of malignancy was studied. Ten patients received corticosteroids. In the entire group, serum ionized calcium (Ca2+), bone gla protein (BGP), 25-hydroxyvitamin D (25OHD), and 1,25-dihydroxyvitamin D (1,25(OH)2D) were all lower than in age-matched controls, and carboxy-terminal parathyroid hormone (CPTH) was higher. Although both corticosteroid- and noncorticosteroid-treated patients had decreased BGP values, the corticosteroid-treated patients had lower BGP levels than those not on steroids (4.24 +/- 0.70 SE vs. 11.50 +/- 2.20 ng/ml; P less than 0.005). Patients on corticosteroids had lower 1,25(OH)2D values than controls (18.81 +/- 2.71 vs. 27.83 +/- 1.17 pg/ml; P less than 0.01), whereas those not on corticosteroids had normal 1,25(OH)2D values. These results suggest that patients with nonhypercalcemic malignancy have nutritional vitamin-D deficiency and secondary hyperparathyroidism with perhaps corticosteroid-induced suppression of serum 1,25(OH)2D and BGP. The decreased levels of serum BGP in the nonsteroid-treated patients suggest, in addition, a defect in osteoblast function.

Low-dose streptozocin-induced diabetes in mice. Electron microscopy reveals single-cell insulitis before diabetes onset

We investigated the morphology of mouse islets 5 days after completion of low-dose streptozocin treatment of C57BL/6 mice by electron microscopy. At this stage, mice were still normoglycemic and light microscopy did not reveal massive islet infiltration. The electron-microscopic investigation revealed two characteristics indicative of ongoing islet cell destruction. In all islets investigated, lysed islet beta-cells were recognized by disrupted plasma membranes and concomitantly decreased plasma contrast. Many of the lysed islet beta-cells still contained numerous insulin granules. We also found immunocytes scattered throughout the islets, most of which could be identified as macrophages. Some were found engaged in phagocytosis of islet beta-cell debris. This early stage of islet lesion termed single-cell insulitis is followed by the well-known later stage of massive infiltration easily recognized in light microscopy. Administration of silica particles to mice treated with low-dose streptozocin inhibited macrophage infiltration of islets as shown by immunocytochemistry with macrophage-specific monoclonal antibody F4/80. In parallel, the development of hyperglycemia was suppressed. The observations favor a pathogenic role of macrophages in islet destruction.

The relation of essential hypertension to feelings of anxiety, depression and anger

Franz Alexander (1939) offered the hypothesis a number of years ago that hypertension can result from the inhibition of feelings of anger. Although a great deal of research has been done to test this hypothesis, the results remain equivocal. Part of the difficulty is that usually only anger was examined, making it impossible to determine the extent to which the results were specific to anger and not general for other negative emotions. A second prevalent problem has been the failure to match hypertensive and control groups on demographic variables that may be relevant to the relationship of hypertension to anger and its expression, such as education, economic level, and age. A third problem is that most studies have investigated only male hypertensives, thereby limiting the generality of the findings. The present study compares male and female hypertensives with carefully matched controls on measures of anxiety, depression, and anger and its suppression.

Cellular immunity and T-lymphocyte subsets in young children with acute measles

The changes occurring in the T-cell subsets during acute symptomatic measles were examined in ten malnourished and 18 well nourished hospitalized children younger than 5 years of age (median age 14 months). A significant decrease in total lymphocyte count was observed, which was due mainly to a decrease in helper/inducer T lymphocytes, whereas the suppressor/cytotoxic T-lymphocyte subset remained unchanged. Consequently, helper/suppressor ratio decreased significantly during the acute phase of the disease. A reduced response to mitogens (PHA, Con A, PWM) was also observed. Malnourished infants showed a trend toward a deeper depression in both helper and suppressor T cells during the acute phase than well nourished children, whereas the helper/suppressor ratio remained similar in the two groups.

Unusual stable isotope ratios in amino acid and carboxylic acid extracts from the Murchison meteorite

Much effort has been directed to analyses of organic compounds in carbonaceous chondrites because of their implications for organic chemical evolution and the origin of life. We have determined the isotopic composition of hydrogen, nitrogen and carbon in amino acid and monocarboxylic acid extracts from the Murchison meteorite. The unusually high D/H and 15N/14N ratios in the amino acid fraction (delta D = 1,370% after correction for isotope exchange; delta 15N = 90) are uniquely characteristic of known interstellar organic materials. The delta D value of the monocarboxylic acid fraction is lower (377%), but still consistent with an interstellar origin. These results confirm the extraterrestrial origin of both classes of compound, and provide the first evidence suggesting a direct relationship between the massive organo-synthesis occurring in interstellar clouds and the presence of pre-biotic compounds in primitive planetary bodies. The isotope data also bear on the historical problem of distinguishing indigenous material from terrestrial contaminants.

Deranged bone mineral metabolism in chronic alcoholism

Chronic alcoholic subjects may suffer from osteopenia with either osteomalacia or osteoporosis as the main histologic finding. The reasons may be multifactorial, including nutrition, direct effects of alcohol on bone, and deranged liver function. Seventeen asymptomatic subjects with chronic alcoholism were studied. Serum PTH (carboxyl and midmolecule fragments), 25 hydroxyvitamin D [25(OH)D], 1-25 dihydroxyvitamin D [1-25(OH)2D], and ionized calcium were measured in each subject. In addition to these tests, we employed a sensitive technique of dual photon absorptiometry to measure vertebral bone density and a radioimmunoassay of serum bone gla protein (BGP) to estimate osteoblast function. Our results show that subjects suffering from chronic alcoholism had significantly lower serum 25(OH)D and higher ionized calcium, BGP, PTH (midmolecule) and 1,25(OH)2D while four patients had bone density values below the fracture threshold (0.96 g/cm2). These findings demonstrate that asymptomatic patients with chronic alcoholism have deranged bone mineral metabolism including abnormal BGP and some subjects may even have abnormal dual photon absorptiometry measurements. These particular subjects may be at risk in the future for developing osteopenia and consequent vertebral compression fractures.

1,25-Dihydroxyvitamin D3 modulates glucocorticoid-induced alteration in serum bone Gla protein and bone histomorphometry

Glucocorticoid excess is associated with alterations in the vitamin D endocrine system. The aim of this study was to assess change in serum bone Gla protein (BGP) after low and high dose cortisone acetate treatment and to assess whether these alterations are altered or attenuated by 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] administration. Five groups of rats were studied and compared to a control group [cortisone acetate in doses of 0.2, 3.3, and 5.0 mg/100 g BW; 1,25-(OH)2D3 in a dose of 100 ng/100 g BW; and a combination of 1,25-(OH)2D3 (100 ng/100 g BW) plus cortisone acetate (3.3 mg/100 g BW)]. Each animal received daily sc injections for 27 days. BGP decreased significantly by day 7 in the two groups receiving high doses of cortisone acetate compared to control group values (65.20 +/- 4.38 vs. 150.18 +/- 6.13 ng/ml in the intermediate dose group and 91.57 +/- 5.30 vs. 150.18 +/- 6.13 ng/ml in the high dose group; P less than 0.01); this effect persisted until day 28. Histomorphometry revealed decreased formation and resorption in the two high dose cortisone acetate groups, whereas low dose cortisone acetate produced no histological change. The combination therapy lessens any change in BGP until day 28 when BGP was lower than the control value (P less than 0.01); histomorphometry showed that combination therapy prevents the effect of cortisone acetate by increasing bone formation and resorption. The data demonstrate that high doses of cortisone acetate suppress bone formation and that this is reflected in the low serum BGP values. Thus, BGP may be a marker of glucocorticoid-induced bone disease. 1,25-(OH)2D3 protects against glucocorticoid-induced bone disease and the normal BGP level reflects this.

Serum bone gla protein (BGP) and other markers of bone mineral metabolism in postmenopausal osteoporosis

Bone gla protein, the vitamin K-dependent protein synthesized by osteoblasts and measured in blood by radioimmunoassay, has been used as an index of the rate of bone turnover. The relationship of bone gla protein with other markers of bone mineral metabolism was determined in 31 untreated postmenopausal women with the osteoporotic syndrome. In addition to serum osteocalcin (BGP) we measured parathyroid hormone (PTH) (carboxyl and mid-molecule fragments), 25(OH)D, alkaline phosphatase, estradiol (E2), estrone (E1), dietary calcium intake, 24 hour urinary calcium excretion, and bone mineral density by CT scan of the lumbar vertebrae. Significant osteopenia was present on CT in untreated postmenopausal osteoporotic women (bone density in 18 out of 31 was below the critical value of 60 mg/cm3). Serum BGP correlated positively with CT scan (r + 0.647, P less than 0.001). CT and age were negatively correlated (r - 0.661, P less than 0.001) while CT and E2 showed a positive correlation (r + 0.554, P less than 0.01). Unexpectedly, BGP and age revealed a significant negative correlation (r - 0.421, P less than 0.05). These findings suggest a state of low bone turnover in this group with untreated postmenopausal osteoporosis.