Physiologic load-bearing characteristics of autografts, allografts, and polymer-based scaffolds in a critical sized segmental defect of long bone: an experimental study.

BACKGROUND: To address the challenge of treating critical sized intercalary defects, we hypothesized that under physiologic cyclic loading, autografts, allografts, and scaffolds loaded with and without human mesenchymal stem cells (hMSCs) would have different biomechanical characteristics. METHODS: Using a rat femoral defect model, 46 rats were assigned to four groups, ie, autograft (n = 12), allograft (n = 10), scaffold (n = 13), and scaffold with hMSCs (n = 11). The scaffold groups used a 5 mm segment of scaffold composed of 80% poly-ε-caprolactone and 20% hydroxyapatite. Rats were sacrificed 4 months postoperatively, and the repairs were assessed radiographically and biomechanically. RESULTS: Autograft and allograft groups exhibited the most bridging callus, while the scaffold/hMSCs group had more callus than the scaffold repairs. Although signs of radiographic healing did not accurately reflect restoration of mechanical properties, addition of hMSCs on the scaffold enhanced bone formation. The scaffold alone group had significantly lower elastic and viscous stiffness and higher phase angles than other repairs and the contralateral controls. Addition of hMSCs increased the elastic and viscous stiffness of the repair, while decreasing the phase angle. CONCLUSION: Further comparative analysis is needed to optimize clinical use of scaffolds and hMSCs for critical sized defect repairs. However, our results suggest that addition of hMSCs to scaffolds enhances mechanical simulation of native host bone.

Relationship of insulin resistance and hyperinsulinemia to blood pressure during pregnancy.

The purpose of our study was to examine the relationship between insulin resistance and blood pressure during pregnancy and to determine to what extent insulin resistance is related to the subsequent development of pregnancy-induced hypertension. The study population consisted of 292 women who had serum insulin, glucose and insulin-glucose ratios determined at 26-28 weeks gestation in a fasting state and 1 hr after a 50-g oral glucose challenge. These were compared with blood pressures at 26-28 weeks gestation and in the late third trimester. A statistically significant correlation exists overall between (1) blood pressure at 26-28 weeks gestation and both fasting insulin and insulin-glucose ratios, as well as (2) systolic blood pressure at term and fasting insulin levels. However, when controlled for confounding variables including body mass index, race and age, no statistically significant relationship remained. The metabolic variables in patients with pregnancy-induced hypertension were not statistically different from the normotensive patients. In conclusion, this study demonstrates that insulin resistance and hyperinsulinemia are not major determinants of blood pressure during pregnancy.

Fluvastatin with and without niacin for hypercholesterolemia.

Seventy-four patients with plasma low-density lipoprotein cholesterol levels > or = 160 mg/dl after an American Heart Association phase 1 diet were randomized to double-blind treatment with fluvastatin, 20 mg/day, or placebo for 6 weeks. Immediate-release niacin was then added to both treatment regimens and titrated to a maximum of 3 g/day for a further 9 weeks. After 6 weeks of fluvastatin monotherapy, low-density lipoprotein cholesterol levels decreased by 21% (p < 0.001 vs placebo), and after the addition of niacin, response was potentiated to 40% compared with 25% for the niacin control group at study end point (p < 0.001). Fluvastatin, alone and in combination with niacin, also significantly improved high-density lipoprotein cholesterol (increases of about 30%) and triglyceride profiles (decreases of approximately 28%) from baseline. Lipoprotein(a) decreased by 37% in those receiving fluvastatin-niacin but was unaltered in those receiving fluvastatin alone. No serious adverse events were ascribed to fluvastatin, and no cases of myositis were observed. Small, transient, asymptomatic increases in aspartate aminotransferase were noted with fluvastatin-niacin treatment but were not considered clinically relevant. Although the fluvastatin-niacin combination in this study was without evidence of significant transaminitis, myopathy, or rhabdomyolysis, it would seem prudent to continue to monitor its safety with longer term use. In conclusion, fluvastatin, both as monotherapy and in combination with niacin, proved to be an effective, safe, and well-tolerated therapeutic alternative for hypercholesterolemia.

Fluvastatin and niacin in hypercholesterolemia: a preliminary report on gender differences in efficacy.

A total of 74 hypercholesterolemic patients were randomized to receive double-blind treatment for 6 weeks with either 20 mg of fluvastatin daily or placebo. Open-label niacin, to a maximum of 3 g daily, was added to each treatment for a further 9 weeks. Changes in lipid parameters were derived from averaged data, with monotherapy at weeks 3 and 6 and with combination therapy at weeks 12 and 15. The reduction in low-density lipoprotein cholesterol (LDL-C) was significantly greater with fluvastatin (20.8%) compared with placebo (p < 0.001) after 3-6 weeks of treatment. At the end of 12-15 weeks, the addition of niacin potentiated the response to 43.7% with the fluvastatin+niacin combination and to 26.5% with the placebo+niacin combination (p < 0.001, vs baseline and between treatment groups). Significant gender differences were noted in the LDL-C response to the fluvastatin+niacin combination. Women achieved LDL-C reductions of 54.6% whereas men achieved reductions of 38.2% (p < 0.0005, between gender groups). Women also tended to have greater LDL-C reductions with the placebo+niacin combination, compared with men (p < 0.05). At the end of 12-15 weeks, there were HDL-C increases of 33.1% (p < 0.001) whereas triglyceride levels declined by 32.3% (p < 0.001). In conclusion, fluvastatin, both as monotherapy and in combination with niacin, proved to be an effective and well-tolerated alternative for the treatment of hypercholesterolemia. The differential response in LDL-C between men and women should be further explored in other trials of lipid-lowering therapy.

Combination therapy with fluvastatin and niacin in hypercholesterolemia: a preliminary report on safety.

A double-blind, randomized study was undertaken to evaluate the efficacy and safety of fluvastatin as monotherapy and as combination therapy with niacin in the treatment of hypercholesterolemia refractory to diet. Seventy-four patients with plasma low-density lipoprotein cholesterol (LDL-C) levels > or = 160 mg/dL were treated with fluvastatin, 20 mg/d, or placebo for 6 weeks. Thereafter, immediate-release niacin, at a dosage titrated to a maximum of 3 g/d, was added to both regimens for another 9 weeks. All adverse events were monitored, with particular attention to the evaluation of liver and muscle enzymes. Initial analysis of the data shows that fluvastatin and its combination with niacin was well tolerated and was not associated with any serious adverse events. Small, transient, asymptomatic rises in aspartate aminotransferase (AST) occurred in 28.9% of fluvastatin-niacin treated patients compared to 8.3% in the niacin-placebo control arm (p < 0.05). These were considered clinically insignificant in that no transaminase elevations > 3 times the upper limit of normal occurred. No evidence of myopathy, creatine kinase levels exceeding 10 times the upper limit of normal, myositis, or rhabdomyolysis were demonstrated in this short-term trial. The majority of adverse events resulting in patient withdrawals were ascribed to niacin therapy and included cutaneous vasodilatation, flushing, itching, and rash. These preliminary results suggest that fluvastatin, both alone and combined with niacin, is an effective, safe, and well-tolerated treatment for hypercholesterolemia.

Uric acid level increases in humans engaged in gambling: a preliminary report.

The effect of gambling and gaming on plasma levels of uric acid was studied. Blood samples were obtained from normal subjects while they gambled for money or while they played checkers without betting. There was an interaction of time and activity reflecting primarily an association of increased uric acid levels during gambling over time, compared with gaming and relaxation. This indicates that gambling can increase plasma levels of uric acid.

Ten-year experience with an exercise-based outpatient life-style modification program in the treatment of diabetes mellitus.

Exercise is frequently recommended in the treatment of diabetes mellitus. Nevertheless, its use has been limited in clinical practice, and concerns about safety and efficacy persist. We have reviewed a 10-yr experience with 255 patients enrolled in a comprehensive diabetes program that emphasized physical training. A low maximal oxygen uptake (VO2max) was found in patients with non-insulin-dependent diabetes mellitus compared with sedentary control subjects. This was not accounted for by autonomic neuropathy and is unlikely to be due to subtle differences in life-style. Exercise-related proteinuria was common and occurred in 29% of patients and was associated with higher blood pressure levels at rest and during exercise, impaired VO2max, and decreased R-R interval variation. Regular exercise was associated with a modest decrease in resting and exercise blood pressure. Glycosylated hemoglobin levels and plasma triglycerides improved only in patients with non-insulin-dependent diabetes mellitus. Insulin requirements were significantly reduced in patients with insulin-dependent diabetes mellitus. Compliance for up to 3 mo in the program was acceptable but longer-term compliance was poor. Serious complications during the program were rare. Our experience suggests a program of regular aerobic training can be safely and effectively used in an outpatient population with diabetes mellitus for up to 3 mo.

Effects of pravastatin on cholesterol metabolism in Watanabe heritable hyperlipidemic rabbits.

Pravastatin, a competitive inhibitor of hydroxymethylglutaryl CoA reductase (HMG CoA reductase) is a potent hypocholesterolemic agent in humans as well as experimental animals, including the Watanabe heritable hyperlipidemic (WHHL) rabbit, lacking low density lipoprotein (LDL) receptor activity. We studied the effect of pravastatin on several aspects of cholesterol metabolism in WHHL rabbits. Cholesterol synthesis was measured by intraperitoneal injection of radioacetate and determination of its incorporation into the nonsaponifiable lipid fraction of liver, plasma, adrenal glands and gonads. A single dose of pravastatin (25 mg/kg) caused statistically significant inhibition of hepatic cholesterol synthesis at 2, 6, 12, and 24 hours following oral administration. By 48 hours, the inhibitory effect of the drug was no longer demonstrable. The pattern of radioactivity in the plasma was similar to that in the liver. The drug had no statistically significant effect on cholesterol synthesis in adrenal glands and gonads, suggesting a selective effect on the liver. Cholesterol absorption was studied after simultaneous oral administration of [3H] cholesterol and [14C] beta-sitosterol. Pravastatin, 50 mg/kg for 10 days had no effect on fecal excretion of the radiolabelled steroids over 4 days. At 24 hours the plasma level of [14C] cholesterol was 1/3 that of control in pravastatin treated animals (p < 0.05) but did not undergo an accelerated decline over 6 days. The activity of acyl CoA: cholesterol acyltransferase (ACAT) in intestinal mucosa and the concentration of hepatic cholesterol were similar in animals treated over one year with pravastatin 50 mg/kg/day or with placebo. Our data do not allow us to make definitive conclusions about the effect of pravastatin on cholesterol absorption but are compatible with the hypothesis that the drug inhibits the hepatic synthesis as well as the assembly of cholesterol into lipoproteins.

Pravastatin decreases serum lipids and vascular cholesterol deposition in Watanabe heritable hyperlipidemic (WHHL) rabbits.

The effects of long term administration of pravastatin (a competitive inhibitor of hydroxymethylglutaryl CoA reductase) were assessed by measuring serum lipids and aortic and coronary atherosclerosis in Watanabe Heritable Hyperlipidemic (WHHL) rabbits. Six-month-old WHHL rabbits were given either 50 mg/kg/day of the drug or vehicle. The rabbits were sacrificed following 6 or 12 months of treatment and serum cholesterol and triglycerides and aortic cholesterol and hydroxyproline were measured. Atherosclerotic plaques in the aorta and coronary arteries were quantified with morphometric methods. Mean serum cholesterol +/- SEM (n) in the control vs. pravastatin groups after 6 months were: 535 +/- 34 (11) vs. 411 +/- 22 (12) (p less than 0.005) and after 12 months 458 +/- 43 (9) vs. 309 +/- 29 mg/dl (12) (p less than 0.005). In the pravastatin group, percent aortic area covered with plaque and aortic cholesterol content were reduced 35% (ns) and 55% (p less than 0.05) at 6 months, and 26% (ns) and 44% (ns) at 12 months, respectively. Little difference was found in serum triglycerides and aortic hydroxyproline in the 2 groups. There was strong correlation of serum cholesterol with aortic cholesterol content (r = 0.61, p less than 0.003) and with the percent aortic plaque area (r = 0.67, p less than 0.001), at 12 months. Morphometric analysis of wall thickness and lumen area of major coronary arteries revealed no significant differences in the 2 groups. In conclusion, pravastatin effectively lowered the serum cholesterol level in an animal model defective in low density lipoprotein receptors; this reduction was strongly correlated with amelioration of such atherosclerotic processes as lipid deposition and plaque formation.

Atherosclerosis and glomerulosclerosis in WHHL rabbits and obese Zucker rats.

The aorta and the kidney of 12 month old hyperlipidemic WHHL and obese Zucker rats, were examined morphologically. The WHHL developed severe and premature atherosclerosis but did not develop glomerulosclerosis. In contrast, the Zucker rats did not manifest atherosclerosis of the aorta, but developed glomerulosclerosis. These two animal models could be useful in understanding the roles of heterogeneous lipoprotein particles, genetic susceptibility, hemodynamic stress, and mesangial interactions with lipoproteins in the development of glomerulosclerosis.

Bilateral adrenal myelolipomas with Cushing's syndrome.

A 24-year-old woman with non-pituitary dependent Cushing's syndrome was found to have bilateral adrenal myelolipomas at surgery. These benign tumors consist of bone marrow and fat and are uncommon incidental findings that are discovered by computed tomography. Myelolipomas have rarely been associated with Cushing's syndrome, but the cause of the syndrome has not always been defined, because the reports preceded modern diagnostic methods. Careful examination of the adrenal glands from our patient showed a fusion of myelolipoma elements and adrenal cells without distinct adenomas or the typical nodular pattern of adrenal hyperplasia. This report suggests that adrenal myelolipomas and atypical hyperplasia of the zona fasciculata may be anatomically and functionally related.

Abnormal glucoregulation during exercise in type II (non-insulin-dependent) diabetes.

We studied the effects of exercise on the levels of plasma glucose and glucoregulatory hormones before and after 6 weeks of thrice-weekly physical training in 20 sedentary type II (non-insulin-dependent) diabetic patients and 11 control subjects matched for previous physical activity. Parameters were measured at rest, after 30 minutes of bicycle exercise at 70% to 75% of maximal oxygen uptake, and after 30 minutes of recovery. In the untrained state exercise resulted in a decrease in plasma glucose levels in diabetics but not in controls (-12 +/- 5 v + 4 +/- 2 mg/dL, P less than .01) and the expected drop in plasma insulin level was absent in diabetics. These differences in glucose and insulin response persisted after physical training. There was a tendency for patients with diabetes to have a smaller R-R interval variation during deep breathing, an abnormal resting heart rate response to physical training, and a lesser increment in plasma epinephrine levels following exercise, findings consistent with autonomic dysfunction. Physical training resulted in a blunting of the exercise-induced increment of plasma epinephrine, growth hormone, and lactate levels in control subjects, but not in diabetics. Our data demonstrate a hypoglycemic effect of exercise in mildly hyperglycemic nonobese type II diabetics. Possible causative factors include: hyperglycemia per se, a lack of physiologic suppression of plasma insulin, and abnormalities of autonomic or hypothalamic regulatory function.

The effects of polyoxyethylated cholesterol feeding on hepatic cholesterol synthesis and intestinal cholesterol absorption in rats.

Adduction of ethylene glycol moieties to the 3-hydroxy position of cholesterol produces polyoxyethylated cholesterol (POEC), a water-soluble compound that suppresses cholesterol synthesis and esterification in cultured human fibroblasts. Feeding Sprague-Dawley rats a diet containing 2% (wt/wt) POEC with 10 ethoxy groups resulted in a 3-fold increase in hepatic 3-hydroxy-3-methylglutaryl-CoA reductase activity compared to activity in rats pair-fed a diet of standard rat chow. POEC with an average of 20 ethoxy groups (POEC-20) caused comparable changes in hepatic [2-14C]acetate incorporation into non-saponifiable lipids under ad libitum feeding conditions, significantly reduced cholesterol absorption (18% vs 57%), and increased fecal excretion of neutral steroids (5.1 vs 2.0 mg/g food intake). POEC-20 also reduced cholesterol absorption in rats fed a diet enriched with 2% cholesterol (11% vs 31%). Histologic studies of intestinal mucosa and hepatic tissues from rats fed POEC showed no pathologic changes. These experiments indicate that POEC reduces cholesterol absorption and causes compensatory increases in hepatic cholesterol synthesis.

Stimulation of cholesterol and lipid synthesis by insulin in familial hypercholesterolemic fibroblasts.

Cultured skin fibroblasts from two patients with homozygous familial hypercholesterolemia and three normal subjects were preincubated for 24 hours in medium containing 10% delipidated serum with insulin concentrations of 0.4, 4, or 40 ng/mL. [14C]acetate incorporation into total lipids, cholesterol, and phospholipids was significantly increased in familial hypercholesterolemic cells at insulin concentrations of 0.4 and 4 ng/mL, which had no effect in normal cells. When the data were normalized as percent stimulation over control for individual experiments, [14C]acetate incorporation into cholesterol was comparable at 40 ng/mL in both cell types. Similar results were obtained in cells preincubated in serum free artificial medium. Coordinate increases in the activity of 3-hydroxy-3-methylglutaryl CoA reductase in response to insulin were not found. These studies show that familial hypercholesterolemic cells have an altered lipogenic response to low concentrations of insulin.

Sacral destruction: foraminal lines revisited.

Although imaging techniques have improved greatly in recent years, plain radiography remains the initial imaging method for evaluation of patients with low back pain. The sacrum, in particular, is a difficult structure to evaluate. In reviewing 12 cases, the authors found an unacceptably high rate of missed sacral metastases (83%). Using a photograph and a radiograph of two bony pelvic specimens to represent normal anatomy and the normal appearance of the sacral foraminal lines, sacral destruction is illustrated in six cases. All lesions were neoplastic and most were metastatic. In each case there was destruction of one or more sacral lines. The importance of careful observation for symmetric appearance of these lines is emphasized.

Studies on the mechanism of improved glucose control during regular exercise in type 2 (non-insulin-dependent) diabetes.

The effects of 6 weeks of thrice weekly training on glycaemic control were assessed in 20 sedentary Type 2 (non-insulin-dependent) diabetic patients and 11 control subjects matched for previous physical activity. Maximal oxygen uptake was lower in the diabetic patients than in control subjects before training (26.2 +/- 1.1 versus 32.6 +-/ 1.7 ml X kg-1 X min-1; p less than 0.001). Glycosylated haemoglobin levels decreased in the diabetic patients during the training programme (12.2 +/- 0.5 to 10.7 +/- 0.4%; p less than 0.02). Oral and intravenous glucose tolerance determined 72 h after the last exercise period showed only minimal improvement. Plasma glucose levels were, however, significantly lower at 12 h than 72 h after exercise in eight subjects tested at both time points. These data suggest than an exercise programme can produce a significant decrease in glycosylated haemoglobin levels in Type 2 diabetic males probably due, in great measure, to the cumulative effect of transient improvements in glucose tolerance which follow each individual period of exercise.

The effects of triiodothyronine, hydrocortisone and insulin on lipid synthesis by cultured fibroblasts preincubated in a serum-free medium.

Studies of lipid metabolism in cell cultures are usually carried out after preincubation of cells in media containing lipoprotein-deficient or delipidated serum. The artifacts produced during delipidation prevent the standardization of assays and the study of the role of hormones on lipid metabolism. We studied the effects of triiodothyronine, hydrocortisone, insulin and their combination on cholesterol and fatty acid synthesis in cultured human skin fibroblasts preincubated for 24 h in an artificial medium (medium A) consisting of equal volumes of Dulbecco's modified Eagle's and Ham's F-12 media enriched with transferrin, biotin and calcium pantothenate. In cells preincubated in medium A the incorporation of acetate to cholesterol and the activity of hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase were much lower than in cells preincubated in standard medium containing lipoprotein-deficient serum. Addition of the three hormones caused a marked stimulation of the incorporation of acetate to cholesterol (from 3.1 to 17.7 pmol/min per mg protein), an activity similar to that in cells preincubated in lipoprotein-deficient serum plus hormones. The stimulatory effect of the hormones on HMG-CoA reductase activity was smaller, from 11 to 26 pmol/min per mg protein compared to 83 pmol/min per mg protein in cells preincubated in lipoprotein-deficient serum plus hormones. Most of the stimulatory effect was due to insulin. The lack of coordinate response between these two parameters in cells preincubated in artificial medium could not be explained by (a) stimulation of a post-mevalonate step as measured by the incorporation of mevalonate to cholesterol; (b) the in vitro inactivation of HMG-CoA reductase by phosphorylation: incubation of fibroblast microsomes with Escherichia coli alkaline phosphatase resulted in a decrease in HMG-CoA reductase activity, in contrast to an increase in hepatic microsomes; (c) the presence of inhibitors of HMG-CoA reductase in the microsomal extract. In cells preincubated in medium A the incorporation of acetate to fatty acids and the activities of acetyl-CoA carboxylase and fatty acid synthetase were approximately equal to that of cells preincubated in standard medium containing lipoprotein-deficient serum. Hormones added to medium A caused a stimulation of incorporation of acetate to fatty acids (from 5.1 to 19.8 pmol/min per mg protein), the activity of acetyl-CoA carboxylase (from 494 to 820 pmol/min per mg protein) and of fatty acid synthetase (from 300 to 678 pmol/mg protein). These values were significantly higher than those obtained in cells preincubated with lipoprotein-deficient serum with or without hormones.(ABSTRACT TRUNCATED AT 400 WORDS)

Hyperparathyroidism with asymptomatic hypercalcemia.

The many patients with mild, asymptomatic hypercalcemia identified by automated methods of clinical chemistry pose a challenge to the clinician. Which of them are likely to develop manifestations of primary hyperparathyroidism?