Vitamin D and L-cysteine levels correlate positively with GSH and negatively with insulin resistance levels in the blood of type 2 diabetic patients.

BACKGROUND/OBJECTIVES: Vitamin D, L-cysteine (LC) and glutathione (GSH) levels are lower in the blood of diabetic patients. This study examined the hypothesis that the levels of vitamin D and LC correlate with those of GSH in the blood of type 2 diabetic patients (T2D), and that vitamin D and LC upregulate glutamate-cysteine ligase (GCLC), which catalyzes GSH biosynthesis, in cultured monocytes. SUBJECTS/METHODS: Fasting blood was obtained after written informed consent from T2D (n=79) and healthy controls (n=22). U937 monocytes were pretreated with 1,25 (OH)2 vitamin D (0-25 nM) or LC (0-500 µM) for 24 h and then exposed to control or high glucose (25 mM) for 4 h. RESULTS: Plasma levels of vitamin D, LC, GSH and GCLC protein were significantly lower in T2D versus those in age-matched healthy controls. Multiple linear regression analyses and adjustment for body weight showed a significant positive correlation between plasma levels of vitamin D (r=0.26, P=0.05) and LC (r=0.81, P=0.001) and that of GSH, and between LC and vitamin D (r=0.27, P=0.045) levels. Plasma levels of GSH (r=-0.34, P=0.01) and LC (r=-0.33, r=0.01) showed a negative correlation with triglyceride levels. Vitamin D correlated inversely with HbA1C (-0.30, P=0.01) and homeostatic model assessment insulin resistance (r=-0.31, P=0.03), which showed a significant positive correlation with triglycerides (r=0.44, P=0.001) in T2D. Cell culture studies demonstrate that supplementation with vitamin D and LC significantly increased GCLC expression and GSH formation in control and high-glucose-treated monocytes. CONCLUSIONS: This study suggests a positive relationship between the concentrations of the micronutrients vitamin D and LC and that of GSH. Some of the beneficial effects of vitamin D and LC supplementation may be mediated by an increase in the levels of GSH and a decrease in triglyceride levels in T2D patients.

Parathyroid surgery in pregnancy: review of the literature and localization by aspiration for parathyroid hormone levels.

OBJECTIVE: To review the management of primary hyperparathyroidism in pregnant women by focusing on the use of preoperative localization procedures and minimally invasive parathyroid surgery during pregnancy. STUDY DESIGN: We report the clinical course of two pregnant women with severe hypercalcemia due to primary hyperparathyroidism, as well as review the literature. RESULTS: Primary hyperparathyroidism in pregnant women is associated with high prevalence of maternal and neonatal complications. In women, with severe hypercalcemia, parathyroid surgery during pregnancy reduces fetal and maternal morbidities. Preoperative localization of parathyroid adenomas during pregnancy remains challenging. In selected cases aspiration of nodules suspected of being parathyroid adenomas with the measurement of the parathyroid hormone (PTH) from the aspirate can localize the adenoma, and allow the surgeon to carry out a minimally invasive parathyroidectomy. CONCLUSION: Localization of a suspected parathyroid adenoma by ultrasound-guided aspiration of a lesion and the measurement of the PTH has previously been described in non-pregnant women. Our review of the literature did not identify any previous case of a pregnant woman with primary hyperparathyroidism, where preoperative localization of a parathyroid adenoma was accomplished by aspiration of a suspected lesion followed by a successful minimally invasive parathyroidectomy carried out during pregnancy.

Normoglycemic diabetic ketoacidosis in pregnancy.

The clinical presentation of diabetic ketoacidosis in pregnancy is usually the same as in nonpregnant women, although the blood glucose may not be as high as in the nongravid state. We report a case of a pregnant woman who developed diabetic ketoacidosis with a normal blood glucose and review the pertinent medical literature. A 29-year-old woman with type I diabetes developed diabetic ketoacidosis during induction of labor. She had a glucose level of 87 mg per 100 ml with ketonuria, a metabolic acidosis, and an anion gap of 20 mmol l(-1). Normoglycemic diabetic ketoacidosis during pregnancy is truly unusual but can occur with relatively low, or even normal, blood sugars and necessitates prompt recognition and treatment. In this case, the combination of an initial episode of hypoglycemia and subsequent blood glucose levels below 95 mg per 100 ml led to a prolonged delay in the initiation of a planned insulin infusion for insulin coverage during the induction of labor. A significant ketoacidosis consequently developed, despite the absence of even a single elevated blood glucose measurement. This case illustrated the importance of not withholding insulin in a patient with type I diabetes for more than a few hours even if the blood glucose is normal.

Normal preoperative calcitonin levels do not always exclude medullary thyroid carcinoma in patients with large palpable thyroid masses.

Medullary thyroid carcinoma (MCT) is a sporadic or familial tumor of the parafollicular or C-cells that secretes calcitonin. The sporadic form usually presents with a palpable thyroid nodule or cervical adenopathy, by which time basal calcitonin levels are almost always elevated. Without special stains, fine-needle biopsy may fail to detect MCT. Recently, several investigators have recommended routine measurement of serum calcitonin in patients with nodular thyroid diseases for the preoperative diagnosis of MCT. A 31-year-old woman had a large palpable MCT with normal calcitonin and carcinoembryonic antigen levels before surgery. Fine-needle aspiration (FNA) demonstrated atypical cells but was not diagnostic of MCT. Pathology revealed a 3 x 4.5 x 2.3 cm MCT. Immunochemical stains showed immunoreactivity for calcitonin and synaptophysin, but no immunoreactivity to thyroglobulin. Postoperative basal and pentagastrin-stimulated calcitonin levels have remained undetectable without evidence of recurrent cancer. We have evaluated six other patients with MCT that were palpable. They had preoperative calcitonin levels ranging from 322-50,032 pmol/L. This unique case of a woman with a 4.5-cm MCT and normal preoperative calcitonin levels, emphasizes the need for careful clinical evaluation and FNA biopsy in managing patients with nodular thyroid disease.

Effect of hyperketonemia on plasma lipid peroxidation levels in diabetic patients.

OBJECTIVE: This study was undertaken to examine the effect of ketosis on plasma lipid peroxidation levels in diabetic patients. RESEARCH DESIGN AND METHODS: Plasma levels of lipid peroxidation products (malondialdehyde) and ketone bodies (acetoacetate and beta-hydroxybutyrate) were determined in diabetic patients (n = 70) and age-matched normal volunteers (n = 25). Diabetic patients with total ketone body levels > 1.0 mmol/l were considered hyperketonemic, and those with levels < or = 1.0 mmol/l were considered normoketonemic. RESULTS: After normalization versus total lipids, levels of lipid peroxidation were significantly higher in the plasma of hyperketonemic diabetic patients (P < 0.05), but not in normoketonemic diabetic patients, compared with age-matched normal volunteers. In addition, low ketonemia was associated with lower lipid peroxidation levels when lipid peroxidation and ketonemia were determined in the same patient (n = 7) at two different clinic visits. CONCLUSIONS: This study demonstrated an association between hyperketonemia and increased lipid peroxidation levels in diabetic patients, which suggests that ketosis is a risk factor in the elevated lipid peroxidation levels associated with diabetes. Further investigation is needed to determine whether antioxidant supplementation can be particularly beneficial in reducing lipid peroxidation and complications in type 1 diabetic patients who frequently encounter ketosis.

Disorders of maternal calcium metabolism implicated by abnormal calcium metabolism in the neonate.

Normal fetal and neonatal calcium homeostasis is dependent upon an adequate supply of calcium from maternal sources. Both maternal hypercalcemia and hypocalcemia can cause metabolic bone disease or disorders of calcium homeostasis in neonates. Maternal hypercalcemia can suppress fetal parathyroid function and cause neonatal hypocalcemia. Conversely, maternal hypocalcemia can stimulate fetal parathyroid tissue causing bone demineralization. We report two asymptomatic women, one with previously unrecognized hypoparathyroidism and the other with unrecognized familial benign hypercalcemia, who were diagnosed when their newborn infants presented with abnormalities of calcium metabolism. J.B. was born at 34 weeks' gestation with transient hyperbilirubinemia and thrombocytopenia. At 1 month of age he had severe bone demineralization, cortical irregularities, widening and cupping of the metaphyses, and lucent bands in the scapulae. The total serum calcium and phosphorus were normal with an ionized calcium of 5.4 mg/dL (4.6-5.4). His alkaline phosphatase, parathyroid hormone, and 1,25-dihydroxyvitamin D levels were all increased. P.B., mother of J.B., had no symptoms of hypocalcemia either prior to, or during this pregnancy. She had severe hypocalcemia and hyperphosphatemia, laboratory values typical of hypoparathyroidism. J.N. presented at 6 weeks of age with new onset of seizures and tetany secondary to severe hypocalcemia. The serum phosphorus, creatinine, alkaline phosphatase, and parathyroid hormone levels were normal. At 15 weeks of age his calcium was slightly elevated with a low fractional excretion of calcium. P.N., mother of J.N., had no symptoms of hypercalcemia either prior to, or during this pregnancy. Her serum calcium was 12.7 mg/dL and urine calcium was 66.5 mg/24 hr, with a low fractional excretion of calcium ranging from 0.0064 to 0.0073. P.N. has a brother who previously had parathyroid surgery. Both J.N. and P.N. meet the diagnostic criteria for familial benign hypercalcemia. These cases illustrate the important relationships between maternal serum calcium levels and neonatal calcium homeostasis. They emphasize the need to assess maternal calcium levels when infants are born with abnormal serum calcium levels or metabolic bone disease.

DAX1 mutations map to putative structural domains in a deduced three-dimensional model.

The DAX1 protein is an orphan nuclear hormone receptor based on sequence similarity in the putative ligand-binding domain (LBD). DAX1 mutations result in X-linked adrenal hypoplasia congenita (AHC). Our objective was to identify DAX1 mutations in a series of families, to determine the types of mutations resulting in AHC and to locate single-amino-acid changes in a DAX1 structural model. The 14 new mutations identified among our 17 families with AHC brought the total number of families with AHC to 48 and the number of reported mutations to 42; 1 family showed gonadal mosaicism. These mutations included 23 frameshift, 12 nonsense, and six missense mutations and one single-codon deletion. We mapped the seven single-amino-acid changes to a homology model constructed by use of the three-dimensional crystal structures of the thyroid-hormone receptor and retinoid X receptor alpha. All single-amino-acid changes mapped to the C-terminal half of the DAX1 protein, in the conserved hydrophobic core of the putative LBD, and none affected residues expected to interact directly with a ligand. We conclude that most genetic alterations in DAX1 are frameshift or nonsense mutations and speculate that the codon deletion and missense mutations give insight into the structure and function of DAX1.

Elevated lipid peroxidation and vitamin E-quinone levels in heart ventricles of streptozotocin-treated diabetic rats.

Diabetic patients develop cardiomyopathy characterized mainly by left ventricular contractile dysfunction and congestive heart failure. This study has investigated the effects of diabetes and insulin treatment on lipid peroxidation, vitamin E, and vitamin E-quinone levels in the heart ventricles of rat made diabetic by streptozotocin treatment. Controls were injected with buffer alone; a subgroup of diabetic rats were injected daily with insulin for 2 months. Membrane lipid peroxidation was measured by determining the thiobarbituric acid (TBA)-reactivity. Vitamin E and vitamin E-quinone were measured by using the high pressure liquid chromatography. There was a significant (p < 0.02) increase in the vitamin E-quinone in the heart ventricles of diabetic rats (0.33 +/- 0.05 microgram/mg phospholipid) compared with control rats (0.19 +/- 0.02). This increase was prevented in insulin-treated diabetic rats (0.20 +/- 0.03). Vitamin E levels were higher (14.15 +/- 1.17 micrograms/mg phospholipid) in diabetic rats compared to control rats (9.93 +/- 1.29 (p < 0.03). However, insulin treatment to diabetic rats did not cause any change in vitamin E levels (11.75 +/- 1.02) compared with diabetic rats. TBA reactivity was higher in the heart ventricles of diabetic rats (1.09 +/- 0.11 nmole/mg phospholipid) compared with controls (0.78 +/- 0.08, p < 0.04). Insulin treatment to diabetic rats prevented the increase in the lipid peroxidation (0.79 +/- 0.07); there were no statistically significant differences in TBA-reactivity levels in heart ventricles of insulin-treated diabetic and control rats. This study documents accumulation of vitamin E-quinone and lipid peroxidation products in heart ventricles in diabetic rats, which may have a role in the altered contractile property of the heart ventricles in diabetes.

Thyrotoxic hypokalemic periodic paralysis: report of four cases in black American males.

Thyrotoxic periodic paralysis (TPP) is an unusual complication of a fairly common disease affecting mostly Asian males. In the United States, there have been several reports of TPP in different ethnic populations and it appears that the incidence is approximately one-tenth of that found in Asian countries. Only six reports of TPP in African-Americans could be found in the literature; however, we are reporting four cases diagnosed within a 13-year period at our institution. We conclude that TPP may occur more often in Blacks than previously suspected and should be considered when patients present with unexplained hypokalemia, muscular weakness and rhabdomyolysis. The epidemiology, clinical manifestations, pathophysiology, and treatment of TPP are reviewed.

Reduced vitamin E and increased lipofuscin products in erythrocytes of diabetic rats.

Vitamin E deficiency in erythrocytes causes decreased cell survival, hypercoagulability, and increased adhesiveness to the endothelium. Similar abnormalities are found in erythrocytes of the diabetic population. This study examines the effect of diabetes on vitamin E and lipofuscin products (aging pigments) in erythrocytes of streptozocin-induced diabetic rats. Controls were injected with buffer alone, and a subgroup consisting of insulin-treated diabetic rats were injected daily with insulin for 2 mo. Mean +/- SD vitamin E levels were 23.2 +/- 4.9, 19.4 +/- 3.2, and 25.9 +/- 2.5 nmol/mumol phospholipid. Lipid fluorescence values (relative values/phospholipid) were 11.1 +/- 1.9, 14.1 +/- 2.6, and 11.9 +/- 1.8 (excitation/emission 360/440 nm) in control, diabetic, and insulin-treated diabetic rats, respectively. Differences in vitamin E and lipofuscin products were significant between all control and diabetic groups and diabetic and insulin-treated diabetic groups. Reduction in vitamin E and increases in lipofuscin products in diabetic rats were significant even when values were expressed per micromole Hb or per 100 ml erythrocytes. This study demonstrates that hyperglycemia significantly reduces vitamin E and increases lipofuscin products in erythrocytes of diabetic rats. These effects were prevented with insulin treatment.

Neuroendocrine evaluation in Kleine-Levin syndrome: evidence of reduced dopaminergic tone during periods of hypersomnolence.

A patient with Kleine-Levin syndrome had polysomnography and neuroendocrinological assays performed during asymptomatic (ASMP) and symptomatic (SMP) 24-hr periods. During the SMP, sleep data revealed poor nocturnal sleep efficiency, increased sleep fragmentation and reduced stages 3, 4 and rapid eye movement (REM). No sleep onset REM episodes were seen. Sleep staging in the ASMP was normal. Blood samples were obtained every 20 min and assayed for thyroid-stimulating hormone (TSH), cortisol (CORT), prolactin (PRL) and growth hormone (GH). Patterns of secretion, 24-hr mean and total integrated concentrations, and mean sleep period time values during the ASMP and SMP were compared. The mean 24-hr level of TSH was increased and GH decreased in the SMP. Comparing sleep period time in the SMP to the ASMP, values for TSH and PRL were increased and GH and CORT were reduced in the SMP. These hormone changes support the hypothesis that reduced hypothalamic dopaminergic tone is present in the SMP compared to the ASMP in Kleine-Levin patients.

Effects of diabetes mellitus and aluminum toxicity on myocardial calcium transport.

Diabetics have an increased risk of developing renal insufficiency, as well as congestive heart failure independent of coronary atherosclerotic or hypertensive heart disease. Aluminum toxicity is being recognized with increased frequency in patients with reduced renal function and aluminum accumulates to a greater degree in tissues of patients with diabetes. Studies in patients with end stage renal disease have implicated aluminum overload as a potential cause of reduced cardiac function. Since both diabetes and aluminum decrease the activity of (Ca + Mg)-ATPase, a key enzyme involved in myocardial calcium transport, the interaction of experimental diabetes mellitus and aluminum toxicity on myocardial sarcoplasmic reticulum calcium transport was investigated in rats. Aluminum alone had no effect on (Ca + Mg)-ATPase activity, while activities in both the diabetic ([DM]) and diabetic plus aluminum loaded ([DM + Al]) groups were significantly lower than controls ([C]). Oxalate-dependent calcium uptake in the [DM] rats was slightly, but not significantly lower than controls, however, uptake was markedly reduced in rats which were both diabetic and aluminum loaded. The calcium regulatory protein calmodulin was measured by a functional assay in the soluble fraction of myocardial tissue prepared from each of the four groups. Compared to [C], calmodulin activity was significantly reduced in both the [DM] and [DM + Al] groups but not affected by aluminum alone. These data indicate that diabetes mellitus is associated with decreased myocardial calmodulin activity that may contribute to reduced sarcoplasmic reticulum (Ca + Mg)-ATPase and calcium transport activities and that aluminium toxicity potentiates the adverse effects of diabetes on decreasing sarcoplasmic reticulum calcium uptake.

Elevated lipid peroxidation levels in red blood cells of streptozotocin-treated diabetic rats.

This study was performed to determine whether or not hyperglycemia in diabetes results in elevated levels of lipid peroxidation products in red blood cells (RBC). Diabetes was induced in rats by treatment with streptozotocin. The level of lipid peroxidation products was examined in fresh RBC by measuring their thiobarbituric acid (TBA) reactivity after 2 and 4 months of induction of diabetes. Hyperglycemia was assessed by measuring the level of glycosylated hemoglobin and blood glucose. Results show that lipid peroxidation levels were significantly higher (50% to 84%) in RBC of diabetic rats than in controls. The increase in the level of lipid peroxidation was blocked in diabetic rats in which hyperglycemia was controlled by insulin treatment. Among phospholipid classes, relative percentage of sphingomyelin (SM) was significantly reduced in RBC at both 2 and 4 months of diabetes; whereas phosphatidylethanolamine (PE) levels were higher in RBC at 4 months of diabetes only. The level of phosphatidylcholine (PC) did not differ significantly between RBC of control and diabetic rats. This study suggests a significantly altered lipid composition and an accumulation of lipid peroxidation products in RBC of streptozotocin-treated diabetic rats.

Treatment of hyperglycaemic hyperosmolar non-ketotic syndrome.

Hyperglycaemic hyperosmolar non-ketotic syndrome (HHNS) is a life-threatening complication of uncontrolled diabetes mellitus. This syndrome is characterised by severe hyperglycaemia, a marked increase in serum osmolality, and clinical evidence of dehydration without significant accumulation of ketoacids. HHNS is typically observed in elderly patients with non-insulin-dependent diabetes mellitus, although it may rarely be a complication in younger patients with insulin-dependent diabetes, or those without diabetes following severe burns, parenteral hyperalimentation, peritoneal dialysis, or haemodialysis. Patients receiving certain drugs including diuretics, corticosteroids, beta-blockers, phenytoin, and diazoxide are at increased risk of developing this syndrome. Patients usually present with a prolonged phase of osmotic diuresis leading to severe depletion of both the intracellular and extracellular fluid volumes. Losses of water exceed those of sodium, resulting in hypertonic dehydration. Therefore, correction of the syndrome will ultimately require administration of hypotonic fluids. Patients presenting with HHNS also have significant depletion of potassium and other electrolytes that will need to be replaced. The principal goal at the outset of therapy must be restoration of the intravascular volume to assure adequate perfusion of vital organs. It remains controversial whether 0.9% or 0.45% NaCl should be the initial fluid infused intravenously. We prefer to administer 0.9% NaCl until the vital signs have stabilised and then substitute 0.45% NaCl. 10 to 15 units of regular human insulin should be injected as a bolus, followed by a continuous infusion of approximately 0.1 U/kg/h. Once the blood glucose approaches 13.9 to 16.7 mmol/L (250 to 300) mg/dl, 5% dextrose should be added to the intravenous fluids and the rate of insulin infusion reduced. Following recovery many patients presenting with HHNS will not require long term insulin therapy and can be managed effectively with diet or oral agents. Precipitating causes of HHNS must be identified and treated simultaneously with correction of the metabolic abnormalities. Appropriate management of precipitating illnesses will limit the high mortality associated with HHNS. This review discusses the current state of knowledge concerning the pathogenesis of HHNS, the clinical features of the disorder, and a systematic approach to treatment.

Management of diabetic ketoacidosis.

Diabetic ketoacidosis is an all too frequent and sometimes preventable complication of Type I diabetes mellitus, responsible for significant morbidity and mortality within the diabetic population. Precipitating diseases account for the majority of deaths occurring in patients admitted in diabetic ketoacidosis, but some deaths are still attributable to ketoacidosis alone, despite recent advances in therapy and management. Recognition of the ketoacidotic state is paramount to optimal therapy, and often hinges on the diagnostic acumen of the physician. Since 20 to 30% of patients presenting in diabetic ketoacidosis do so as the initial manifestation of their previously undiagnosed disease, physicians must maintain a high level of suspicion for this condition. Understanding the pathogenetic mechanisms leading to and prevailing in diabetic ketoacidosis will allow physicians to intervene in a rational manner, approaching therapy with specific end-points in mind: (a) restoration of optimal volume status; (b) reversal of acidosis; (c) reduction of serum glucose levels; (d) replacement of specific electrolytes in a timely manner; (c) institution of appropriate therapy for any precipitating cause; and, (f) careful monitoring of the patient's biochemical, physical and mental parameters to allow adjustment in therapy as necessary. The mainstay of treatment for diabetic ketoacidosis is appropriate fluid and insulin therapy. Low-dose intravenous infusion is now the accepted mode of insulin delivery for patients with this condition. Potassium replacement is almost always necessary, often requiring massive amounts of this ion due to the total body depletion seen with the development of ketoacidosis. Controversy still surrounds routine use of phosphate in diabetic ketoacidosis but replacement may be needed if serum levels fall toward the lower limits of normal values, to avoid the potential adverse effects of phosphate depletion. Administration of bicarbonate is also controversial and should be reserved for patients whose pH is less than 7.0 to 7.1 and then it should be added to intravenous fluids, not given as an intravenous bolus. Efforts toward preventing diabetic ketoacidosis should be of prime importance to physician and patient alike. Preventive measures should include patient education about diabetes mellitus, precipitating factors of diabetic ketoacidosis, signs and symptoms of early metabolic decompensation, rational insulin therapy during minor illness and appropriate timing of physician contact to help avoid this serious and sometimes fatal complication of diabetes mellitus.

Lymphocytic adenohypophysitis: clinical, radiological, and magnetic resonance imaging characterization.

Lymphocytic adenohypophysitis is a rare nonneoplastic cause of a pituitary mass. We report the case of an 18-year-old woman who presented with complaints of headaches and visual disturbances after an otherwise uncomplicated pregnancy and delivery. She had an elevated serum prolactin level and a pituitary mass visualized by magnetic resonance imaging (MRI). The tissue removed by transsphenoidal resection was an inflammatory mass composed of lymphocytes, plasma cells, and moderate fibrosis surrounding islands of hyperplastic lactotrophs. This is the first case of lymphocytic adenohypophysitis visualized by MRI. As in this case, lymphocytic adenohypophysitis is frequently confused with a prolactin-secreting pituitary tumor before operation and pathological examination of the tissue. The clinical characteristics and radiological features of and an approach to managing patients with lymphocytic adenohypophysitis are reviewed and discussed.

Antibodies to nuclear antigens in Graves' disease.

A recent publication reported a high prevalence of double-stranded DNA antibodies quantitated by RIA in patients with Graves' disease. We, therefore, measured antibodies to a variety of nuclear antigens in 20 patients with Graves' disease, most of whom where hyperthyroid. Fluorescent antinuclear antibody tests using HEp-2 cells as substrate were positive in serum of 15 of the 20 patients but in only 2 of 20 normal subjects. DNA binding, determined by RIA, was increased in 12 of 18 patients with Graves' disease. However, a more specific indirect immunofluorescence assay for antibodies to double-stranded DNA using Crithidia luciliae was negative in all 20 patients. Furthermore, antibodies to single-stranded DNA, measured by counterimmunoelectrophoresis, and ribonucleoprotein and Sm antigens, measured by double diffusion in agar, were undetectable in all patients tested. These results demonstrate a high frequency of antinuclear antibody in patients with Graves' disease. The presence of antibodies to double-stranded DNA was not confirmed when assayed by the highly specific and sensitive Crithidia luciliae method, suggesting nonantibody DNA binding in the DNA RIA.

Inhibition of erythrocyte calcium transport by cetiedil.

The elevated calcium content found in red cells from patients with sickle cell anemia may be of pathophysiologic importance in the hemolysis and vasoocclusion which characterize this disorder. Cetiedil, an antisickling agent, has been reported to inhibit the activity of enzymes that are stimulated by the calcium regulatory protein calmodulin. To investigate the mechanism by which cetiedil modifies calcium-mediated erythrocyte function, the effect of the drug on the active transport of calcium into inside-out erythrocyte vesicles was examined and its influence on the activities of phosphodiesterase and Ca-ATPase studied. Cetiedil, in the presence of calmodulin, significantly inhibited calcium transport into inside-out vesicles that were prepared with erythrocytes from normal controls and from patients with sickle cell anemia. However, in the absence of calmodulin, no inhibition was observed. Likewise, cetiedil inhibited calmodulin-stimulated, but not basal, activities of phosphodiesterase and Ca-ATPase. These data, along with previous reports, suggest that cetiedil does not act by lowering the intracellular calcium content. It is, therefore, likely that the beneficial effect of cetiedil is due to its ability to protect the red cell from the deleterious consequences of an elevated concentration of intracellular calcium.

Exercise conditioning increases rat myocardial calcium uptake.

To investigate potential mechanisms underlying the enhanced myocardial performance consequent to exercise training, the adrenergic receptors of myocardial tissue and Ca2+ uptake into sarcoplasmic reticulum-enriched fractions from exercise conditioned animals were compared with that of sedentary controls. Female Wistar rats were exercised by swimming 30 min (5 days/wk) for 12 wk. Exercise conditioning was effective in producing myocardial hypertrophy, as reflected by an increase in heart weight (1.179 +/- 0.022 vs. 1.031 +/- 0.020 g, P less than 0.001) and heart weight-to-body weight ratio (3.29 +/- 0.06 vs. 2.77 +/- 0.05 X 10(-3), P less than 0.001) but no difference in body weight. Despite the myocardial hypertrophy, neither the affinity nor the density of the alpha 1-adrenergic receptors or the beta-adrenergic receptors determined by Scatchard analysis of the ligands [3H]prazosin and [3H]dihydroalprenolol were significantly different between the two groups. The basal Ca2+ uptake into the sarcoplasmic reticulum was also similar (9.90 +/- 0.97 vs. 9.04 +/- 0.75 nmol/mg protein/min), but the addition of calmodulin produced a significantly greater increment in Ca2+ uptake into sarcoplasmic reticulum from the exercised-conditioned animals (1.90 +/- 0.23 vs. 1.21 +/- 0.19 nmol/mg protein/min, P less than 0.03). The adenosine triphosphatase (ATPase) activities of the sarcoplasmic reticulum-enriched fractions of the two groups were similar. We conclude that exercise conditioning produces an enhancement of calmodulin-mediated calcium uptake that is independent of any effect on Ca2+-ATPase.