Short-term systemic insulin-like growth factor-1 is unable to prevent cyclosporin A-induced osteopenia in the rat

Immunosuppression with cyclosporin A (CsA) is effective in a number of immune-mediated diseases and in preventing rejection following organ transplantation. We have repeatedly demonstrated that CsA in the rat model produces accelerated bone remodelling with net bone loss, best characterized in trabecular bone. IGF-I holds promise as a treatment for various osteopenic conditions. Although currently a subject of much controversy, various studies have suggested that in vivo it is anabolic to cortical as well as trabecular bone. The purpose of this study was, in part, to further characterize the effects of CsA and IGF-I on trabecular and cortical bone, and to see whether systemic IGF-I is able to modulate CsA's deleterious skeletal effects. Sixty 10 week-old, male, Sprague-Dawley rats were randomized to receive the following daily for 3 weeks: (1) CsA vehicle (veh) per os (po) + recombinant human (rh) IGF-1 veh subcutaneously (sc); (2) CsA 15 mg/kg po + rhIGF-I-veh; (3) CsA-veh + rhIGF-I 200 microg/kg sc; (4) CsA-veh + rhIGF-I 600 microg/kg sc; (5) CsA 15 mg/kg + rhIGF-I 200 microg/kg, and (6) CsA 15 mg/kg + rhIGF-I 600 microg/kg. Rats were weighed and venous blood was sampled serially for determination of glucose, ionized calcium (Ca2+), PTH, vitamin D, and osteocalcin. Following sacrifice on day 20, histomorphometry was performed on double calcein-labeled tibial metaphysis and diaphysis. All rats receiving CsA had elevated levels of blood glucose and osteocalcin by day 9 and vitamin D at day 20. PTH was similar in all groups, and Ca2+ was only raised in the CsA and CsA + IGF-I 200 microg/kg groups. Rats receiving IGF-I 200 microg/kg and IGF-I 600 microg/kg gained more weight than either vehicle- or CsA-treated animals, attesting to IGF-1's anabolic properties. CsA caused severe trabecular bone loss, not prevented by IGF-I; it even further increased the eroded surface. CsA and IGF-I had little effect on cortical bone volume or marrow area. IGF-I increased endocortical matrix synthesis, as evidenced by the increases in the percent endocortical osteoid perimeter, an effect negated by the addition of CsA. This experiment demonstrates that trabecular bone is more susceptible than cortical bone to the deleterious effects of CsA and indicates little role for IGF-1 in the pathophysiology or treatment of CsA-induced bone disease at the given doses and duration of treatment.

T lymphocytes play a critical role in the development of cyclosporin A-induced osteopenia

The T lymphocyte suppressor, cyclosporin A, has been shown to cause high turnover osteoporosis. We postulated that cyclosporin A may exert its effects via the T cell rather than direct activity on bone. In this study we administered cyclosporin A (15 mg/kg.day by gavage) to 11 10-week-old Rowett athymic nude rats and to 12 age-matched immunocompetent Sprague-Dawley rats. Placebo was administered to control groups (n = 12 for both). After 28 days of treatment, the Sprague-Dawley rats displayed high turnover bone loss, but the nude rats were largely unaffected by the drug. Sprague-Dawley treated rats had less than half the percent trabecular area of their controls as measured at the secondary spongiosa of the proximal tibial metaphysis (P < 0.001; strain by treatment, P = 0.007). The same pattern was evident for trabecular number, separation, and thickness (strain by treatment, P = 0.034, P = 0.001, and P = 0.021, respectively). Only the Sprague-Dawley rats had an elevated percent eroded perimeter and an elevated bone area referent bone formation rate (strain by treatment, P = 0.002 and P = 0.0003, respectively). Mass, glucose, ionized calcium, PTH, osteocalcin, 1,25-dihydroxyvitamin D, and creatinine all responded similarly to cyclosporin A regardless of strain. T Lymphocytes thus appear to be a prerequisite for the development of cyclosporin A-induced osteopenia.

Correlation of paroxysmal supraventricular tachycardia, atrial fibrillation, and sinus rhythm with incidences of new thromboembolic stroke in 1476 old-old patients

The relationship between supraventricular tachycardia and the incidence of thromboembolic stroke has not been previously reported. We investigated in a prospective study the incidence of new thromboembolic stroke in 1476 patients, mean age 81 years, with atrial fibrillation, paroxysmal supraventricular tachycardia, or sinus rhythm detected by 24-hour ambulatory electrocardiograms. New thromboembolic stroke developed at 31-month follow-up in 87 of 201 patients (43%) with atrial fibrillation, at 43-month follow-up in 84 of 493 patients (17%) with paroxysmal supraventricular tachycardia, and at 45-month follow-up in 143 of 782 patients (18%) with sinus rhythm (p < 0.0001 comparing atrial fibrillation with paroxysmal supraventricular tachycardia or sinus rhythm). Kaplan-Meier survival curves showed a higher significance of thromboembolic stroke in patients with atrial fibrillation, compared to patients with paroxysmal supraventricular tachycardia or sinus rhythm (log-rank: p < 0.0001). Multivariate Cox regression model showed that independent significant predictors of thromboembolic stroke were: a) atrial fibrillation (relative risk = 3.31); b) prior thromboembolic stroke (relative risk = 2.85); c) sex (relative risk for women = 0.75); and d) age (relative risk = 1.02). These data show that atrial fibrillation is an independent predictor of thromboembolic stroke in elderly patients, and that paroxysmal supraventricular tachycardia is not associated with thromboembolic stroke.

Osteoporosis in pregnancy

Osteoporosis has long been described in pregnant women who developed vertebral fractures in the last trimester or shortly after delivery without underlying disorders. However, this condition appears to be relatively rare and the clinical features, associated metabolic abnormalities and a pathological mechanism have not been fully established. This paper reviews available data on osteoporosis and pregnancy and briefly discusses the relationship between pregnancy and bone mass, calcium homeostasis, systemic skeletal hormones and local factors to help explain the pathophysiology of this unique disorder.

Association of silent myocardial ischemia with new atherothrombotic brain infarction in older patients with extracranial internal or common carotid arterial disease with and without previous atherothrombotic brain infarction

OBJECTIVE

To correlate silent myocardial ischemia with the incidence of new atherothrombotic brain infarction (ABI) in older patients with 40 to 100% extracranial carotid arterial disease (ECAD) with and without prior ABI.

DESIGN

In a prospective study of 208 older patients with 40 to 100% ECAD diagnosed by carotid duplex ultrasonography, 24-hour ambulatory electrocardiograms were obtained to detect silent myocardial ischemia. At 42-month mean follow-up, silent myocardial ischemia was correlated with the incidence of new ABI in patients with and without prior ABI.

SETTING

A large long-term health care facility where 208 older patients with 40 to 100% ECAD and technically adequate 24-hour ambulatory electrocardiograms for detecting silent myocardial ischemia were studied.

PATIENTS

The 208 patients included 68 men and 140 women, mean age 81 +/- 8 years (range 60 to 100). One-hundred three (50%) of the patients had prior ABI.

MEASUREMENTS AND MAIN RESULTS

Sixty-nine (33%) of the 208 patients had silent myocardial ischemia. Mean follow-up was 42 +/- 25 months (range 3 to 101 months). At follow-up, the incidence of new ABI was 64% in patients with prior ABI and 32% in patients with no prior ABI (P < .0001). At follow-up, the incidence of new ABI was 65% in patients with silent ischemia and 40% in patients with no silent ischemia (P = .0005). The multivariate Cox regression model showed that patients with prior ABI have a 2.5 times higher chance of developing new ABI than those without prior ABI after controlling other prognostic variables. Patients with silent ischemia have a 2.1 times higher probability of developing new ABI than those without silent ischemia after controlling other prognostic variables.

CONCLUSIONS

Prior ABI and silent ischemia are independent risk factors for the development of new ABI in patients with 40 to 100% ECAD. This probably reflects that silent ischemia is a marker for more advanced or more significant atherosclerotic disease rather than a causal factor for ABI.

Bone mineral metabolism in T lymphocyte-deficient and -replete strains of rat

The immune and skeletal systems are known to interact. We have repeatedly shown that in contrast to in vitro data, the administration of T lymphocyte immunosuppressants, such as cyclosporin A, leads to an increase in bone resorption and a high turnover osteopenia. The purpose of this study was to characterize the bone metabolism of the T lymphocyte deficient Rowett athymic homozygous (rnu/rnu) nude rat. We wished to determine whether these rats share the bone abnormalities of cyclosporin A-treated rats. Eleven 10-week-old Sprague-Dawley rats and 12 similarly aged nude rats were studied over a 4-week period. Metaphyseal cancellous bone histomorphometry was similar in the two groups of rats and only differed with regard to percentage eroded perimeter (lower in nude rats, p = 0.0008) and longitudinal growth rate (49% lower in nude rats, p < 0.001). The nude rats had less body mass (p < 0.001) but nevertheless gained the same percentage of their body weight over the study period. The athymic rats had lower levels of serum, 1,25-dihydroxyvitamin D (p < 0.014) and serum osteocalcin(p < 0.009), and at the age of 14 weeks the nude rats had lower concentrations of serum creatinine (p = 0.001) and blood ionized calcium (p = 0.0002), yet serum PTH was similar throughout. RNA isolated from the contralateral tibias revealed that the nude group had lower steady-state levels of osteocalcin mRNA despite similar rates of bone formation. In its entirety, the data suggest that T cell deficiency per se is not necessarily associated with high turnover osteopenia.

Signal-averaged electrocardiography and ventricular tachycardia as predictors of mortality after acute myocardial infarction in elderly patients

Signal-averaged electrocardiography and 24-hour ambulatory electrocardiographic monitoring were performed in 121 elderly patients > 6 months after acute myocardial infarction. All patients had asymptomatic complex ventricular arrhythmias and a left ventricular ejection fraction > or = 40%. Rates of sudden, cardiac, and total death were compared between groups with and without nonsustained ventricular tachycardia and between normal and abnormal signal-averaged electrocardiographic studies. The prevalence of an abnormal signal-averaged electrocardiographic study was 36%. Thirty-seven percent of the patients had nonsustained ventricular tachycardia, and the remaining patients had complex ventricular arrhythmias other than ventricular tachycardia. There were 27 sudden and 48 total cardiac deaths, and 66 deaths from all causes during a mean follow-up period of 30 months. Kaplan-Meier survival analysis showed a lower rate of sudden and cardiac death in the group without nonsustained ventricular tachycardia. Although there was a trend toward a lower rate of sudden death in patients with a normal signal-averaged electrocardiogram, there was no statistical difference in the rates of sudden, total cardiac, or total death between patients with normal or abnormal studies. The negative predictive value of having neither an abnormal signal-averaged electrocardiogram nor nonsustained ventricular tachycardia was 94% for sudden death. In elderly patients with complex ventricular arrhythmias and ejection fraction > or = 40% at least 6 months after an acute myocardial infarction, presence of nonsustained ventricular tachycardia predicted a higher rate of sudden and cardiac death. Signal-averaged electrocardiography alone was not predictive.

Usefulness of an abnormal signal-averaged electrocardiogram for predicting cardiac death in elderly persons without heart disease

We found an abnormal signal-averaged ECG in 7 of 51 elderly patients (14%) (mean age 83 years) without clinical evidence of heart disease, and in 1 of 25 volunteers (4%) (mean age 31 years range [17 to 47]) without clinical evidence of heart disease. The data from our prospective study indicate that at 43-month mean follow-up, elderly patients with an abnormal signal-averaged ECG but no clinical evidence of heart disease do not have an increased incidence of sudden cardiac death, total cardiac death, or total death.

Rapamycin: a bone sparing immunosuppressant?

Immunosuppressant therpay is associated with osteoporosis both clinically, post-transplantation, and experimentally. In rats, cyclosporin A (CsA) and FK506 induce a state of high turnover rapid bone loss. After 14 days of administration in immunosuppressive doses, the more recently discovered immunosuppressant, rapamycin, resulted in no change of cancellous bone volume. A longer study over 28 days has now been carried out; contrasting the new drug with CsA and FK506. Sixty, 10-week-old Sprague-Dawley rats were randomly divided into five groups of 12 rats each. The first group served as an aging control. The remaining four groups received, by daily gavage, a combined vehicle placebo, CsA 15 mg/kg, FK506 5 mg/kg, and rapamycin 2.5 mg/kg, respectively. CsA- and FK506-treated rats, but not those treated with rapamycin, demonstrated high turnover osteoporosis with raised serum 1,25(OH)2D (p < 0.05) and elevated serum osteocalcin (p < 0.05). The trabecular bone area was decreased by 66% (p < 0.01) in the CsA group and 56% (p < 0.05) in the FK506-treated group compared with the control animals. The CsA- and the rapamycin-treated groups failed to gain weight and developed severe hyperglycemia (> 20 mmol/l, p < 0.001) by day 14 but which largely resolved by day 28. Unlike the groups treated with CsA and FK506, rapamycin-treated rats had no loss of trabecular bone volume but there was increased modeling and remodeling and a decreased longitudinal growth rate. Rapamycin may thus confer a distinct advantage over the established immunosuppressants in not reducing bone volume in the short term.(ABSTRACT TRUNCATED AT 250 WORDS)

Organ transplantation and osteoporosis

Organ transplantation offers new life to patients who suffer from incurable disease. The problem of rejection of the transplanted organ has been overcome with the use of potent immunosuppressive drugs. These drugs, although they allow graft tolerance and graft survival, also are associated with complications such as osteoporosis. Although factors such as nutrition, gonadal status, and ambulatory status are important, the use of immunosuppressive drugs appears to be the main factor in the development of osteoporosis. The drugs that are responsible for this bone loss are glucocorticoids and the calcineurin phosphatase inhibitors, cyclosporine and tacrolimus. The incidence of bone disease depends, in part, on which organ is transplanted. Kidney transplant recipients appear to be less susceptible to the development of overt osteoporosis than do heart or liver transplant recipients. The most critical period of bone loss in organ recipients appears to be within the first 6 months, with the most dramatic reduction occurring within the first 3 months following transplantation. Trabecular (cancellous) bone of the spine appears to be most at risk, with vertebral fractures occurring most commonly. Transplant recipients should be evaluated by bone mineral densitometry and measurement of vitamin D metabolites, blood urea nitrogen, creatinine, calcium, and phosphate. Markers of bone turnover may help in assessing the rate of remodeling. Gonadal function should be ascertained by measurement of serum testosterone (males) or estradiol (females) levels. Therapy should be directed toward prevention of bone loss as well as helping to restore what already may have been lost. Administration of calcium and vitamin D and sex hormone replacement, if indicated, should be considered.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of medroxyprogesterone acetate on bone metabolism in the oophorectomized, tamoxifen-treated rat

Tamoxifen (TAM) is used primarily in the management of breast cancer, and it also has bone-sparing effects similar to estrogen. In breast cancer patients TAM may have a potential role in the prevention and management of osteoporosis. TAM therapy is associated with uterine hyperplasia, and medroxyprogesterone acetate (MPA) added to the regimen provides protection against this. Due to the potential combined use of MPA and TAM in the clinical setting, this study was conducted to assess whether MPA acted synergistically, dampened, or enhanced the TAM effect on bone. Seventy-five female rats (60 oophorectomized; Ox), were randomized into five groups and received either TAM (0.1 mg/kg.day) and/or MPA (0.3 mg/kg.day) therapy over 28 days as follows: 1) sham; 2) Ox; 3) Ox plus TAM; 4) Ox plus MPA; and 5) Ox plus TAM plus MPA. Blood was sampled on days 0, 14, and 28 for measurement of ionized calcium, PTH, 1,25-dihydroxyvitamin D, osteocalcin, and insulin-like growth factor 1. TAM-treated rats showed a reduction in body weight serum osteocalcin, PTH, and insulin-like growth factor 1. Histomorphometric analysis of the proximal tibia showed less cancellous bone volume in Ox rats, and the effect was attenuated by TAM. MPA alone had no significant effect on cancellous bone volume. All the bone formation parameters evaluated (bone formation rate, mineral apposition rate, percent calcein-labeled surface, and number of osteoblasts) were higher in Ox rats compared with sham-operated rats and were lower in TAM-treated rats compared with Ox rats. These parameters were not changed by MPA, alone or in combination with TAM. The number of osteoclasts was higher in Ox rats compared with sham-operated rats and was reduced by TAM. MPA therapy alone or in combination with TAM did not affect number of osteoclasts. These results suggest that MPA neither dampened nor enhanced the effect of TAM on bone.

Amylin increases bone volume but cannot ameliorate diabetic osteopenia

Amylin is normally secreted in a regulated fashion by the pancreatic beta-cells in parallel with insulin and has been reported to have bone-conserving properties. Type I diabetes mellitus results in a low-turnover osteopenia in the presence of decreased amylin, which is in contrast to type II diabetes where less bone loss, in the presence of high amylin levels, occurs. We investigated the effects of amylin on bone mineral metabolism in normal and diabetic (streptozotocin-induced) rats, in order to ascertain whether amylin would modify the streptozotocin-induced diabetic osteopenia. Ten-week-old male Sprague-Dawley rats were randomized as follows: group A (n = 18) received normal saline; group B (n = 18) received amylin; group C, diabetic rats (n = 23), received normal saline; and group D, diabetic rats (n = 23), received amylin. Amylin (100 pmol/100 g b.w.) was administered by a daily subcutaneous injection. Double calcein-labeled tibiae were removed for histomorphometric analysis followed sacrifice on day 19. Results showed no difference in blood ionized calcium between groups. Blood glucose remained above 600 mg/dl in the diabetic animals and was not affected by the administration of amylin. Serum osteocalcin, insulin-like growth factor-1 (IGF-1), parathyroid hormone (PTH), and 1,25 dihydroxyvitamin D [1,25(OH)2D] were significantly lower in the diabetic rats compared with control group A by day 19. Amylin produced higher levels of serum osteocalcin in group B on day 9 (P < 0.05) compared with controls but returned to control values (group A) by day 19; no such change occurred in the diabetic group.(ABSTRACT TRUNCATED AT 250 WORDS)

Azathioprine alone is bone sparing and does not alter cyclosporin A-induced osteopenia in the rat

The immunosuppressant agent cyclosporin A (CsA) induces a high turnover osteopenic state, while the effect on bone of the antimetabolite azathioprine, a drug often used in conjunction with CsA in transplant patients, is less clear. This study was therefore designed to investigate the outcome of azathioprine administration, with reference to CsA, on bone mineral metabolism using the rat model. Four groups of 10-week-old male Sprague-Dawley rats (12 per group) were randomly allocated to receive by daily gavage for a 28-day period: (1) no treatment (control group); (2) azathioprine 1.5 mg/kg bw; (3) CsA 15 mg/kg bw; and (4) a combination of azathioprine and CsA, as described above. Rats were weighed and blood assayed serially for osteocalcin, ionized calcium, 1,25-dihydroxyvitamin D (1,25(OH)2VitD), and parathyroid hormone (PTH). Tibiae were removed following sacrifice on day 28 after double calcein labeling for histomorphometric analysis. Immunosuppressant groups were compared with nontreated control. We confirmed our previous findings that CsA induces a state of high turnover bone loss which is accompanied by a diminished gain in body weight (p < 0.01) and elevated serum osteocalcin (p < 0.001) and 1,25(OH)2VitD levels (p < 0.001). Azathioprine treatment alone did not alter ionized calcium, 1,25(OH)2VitD, or PTH levels. However, there was biochemical evidence of impaired osteoblastic activity as seen by decreased osteocalcin values on days 14 and 28 (p < 0.001). Azathioprine caused no loss of bone volume nor any deviation from the norm in mineral apposition rate, bone formation rate, or longitudinal bone growth. All three treatment groups showed an increased recruitment of osteoclasts to the bone surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood lactate concentration following exercise: effects of heat exposure and of active recovery in heat-acclimatized subjects

The purpose of this study was to examine the effect of ambient heat on the decrease in blood lactate concentration ([LA]bl) during passive and during active recovery. Ten trained men performed six 1-min bouts of exercise at 100% VO2peak on a cycle ergometer, with 1-min rest between the bouts. Each subject exercised twice in thermoneutral (22 degrees C, 40% RH, TN), and twice in hot (35 degrees C, 30% RH, H) conditions. Exercise was followed by either 40 min of passive recovery (sitting) or by 20 min active recovery (cycling at 35% VO2peak) and 20 min passive recovery, named thereafter, 'active recovery'. Capillary blood lactate was measured before, 1 min after, and every 5 min during recovery. Heart rate (HR), rectal and skin temperatures (Tre, Tsk) were monitored continuously. VO2 was measured prior to exercise, during the last exercise bout, the first 10 min of recovery, and periodically thereafter. Post-exercise [LA]bl was similar in all treatments (13.5 +/- 1.8, 13.0 +/- 1.3, 14.8 +/- 4.1, 13.3 +/- 2.6 mmol.l-1 for TN-active, TN-passive, H-active and H-passive, respectively). [LA]bl was significantly lower during active, compared to passive recovery in both, TN and H conditions. Environmental heart did not independently affect [LA]bl during passive or active recovery. Exercise resulted in an elevation in Tre in all treatments, with a significantly higher Tre during active recovery in H compared to the other sessions. Likewise, no differences in HR and in VO2 were observed between H and TN conditions during active nor during passive recovery.(ABSTRACT TRUNCATED AT 250 WORDS)

A new rapid and reproducible homologous immunoradiometric assay for amino-terminal parathyroid hormone in the rat

Measurement of parathyroid hormone (PTH) in the rat is most often performed with competitive ligand radioimmunoassays (RIA) utilizing heterologous antibodies. We report here the validation of a newly developed homologous immunoradiometric assay (IRMA) for rat PTH. Two different goat antibodies to the amino-terminal sequence of rat PTH are utilized; one is immobilized onto plastic beads to capture the PTH molecules and the other is radiolabeled for detection. To test this new IRMA, 30 Sprague-Dawley rats were randomized into three treatment groups to receive by intraperitoneal injection: (1) saline 1 ml/kg (control); (2) calcium chloride 40 mg/kg (hypercalcemic); and (3) EDTA 300 mg/kg (hypocalcemic). Blood samples were taken at 0, 30, 60, 180, and 300 minutes after administration of the assigned treatment for measurement of ionized calcium (Ca2+) and serum PTH. Most of the variance in PTH levels was found to be due to changes in Ca2+ (r2 = 0.780, P < 0.0001). There was also a close temporal relationship between the two, with the highest levels of PTH occurring at the same measured time points as the lowest Ca2+, and vice versa. The measured detection limit of the IRMA was 3 pg/ml with intra- and interassay coefficients of variation of 1.74% and 3.07%, respectively. Serial dilutions with pooled rat serum, synthetic rat PTH-(1-34), and synthetic human PTH-(1-34) showed good parallelism with increased specificity for the pooled and synthetic PTH, despite a degree of crossreactivity with hPTH.(ABSTRACT TRUNCATED AT 250 WORDS)

Isotopic analyses of nitrogenous compounds from the Murchison meteorite: ammonia, amines, amino acids, and polar hydrocarbons

The combined volatile bases (ammonia, aliphatic amines, and possibly other bases), ammonia, amino acids, and polar hydrocarbons were prepared from the Murchison meteorite for isotopic analyses. The volatile bases were obtained by cryogenic transfer after acid-hydrolysis of a hot-water extract and analyzed by combined gas chromatography-mass spectrometry of pentafluoropropionyl derivatives. The aliphatic amines present in this preparation comprise a mixture that includes both primary and secondary isomers through C5 at a total concentration of > or = 100 nmoles g-1. As commonly observed for meteoritic organic compounds, almost all isomers through C5 are present, and the concentrations within homologous series decrease with increasing chain length. Ammonia was chromatographically separated from the other volatile bases and found at a concentration of 1.1-1.3 micromoles g-1 meteorite. The ammonia analyzed includes contributions from ammonium salts and the hydrolysis of extractable organic compounds, e.g., carboxamides. Stable isotope analyses showed the volatile bases to be substantially enriched in the heavier isotopes, relative to comparable terrestrial compounds delta D < or = +1221%; delta 13C = +22%; delta 15N = +93%). Ammonia, per se, was found to have a somewhat lower delta 15N value (+69%) than the total volatile bases; consequently, a higher delta 15N (>93%) can be inferred for the other bases, which include the amines. Solvent-extractable polar hydrocarbons obtained separately were found to be enriched in 15N (delta 15N = +104%). Total amino acids, prepared from a hydrolyzed hot-water extract by cation exchange chromatography, gave a delta 15N of +94%, a value in good agreement with that obtained previously. Nitrogen isotopic data are also given for amino acid fractions separated chromatographically. The delta 15N values of the Murchison soluble organic compounds analyzed to date fall within a rather narrow range (delta 15N = +94 +/- 8%), an observation consistent with their formation, or formation of their precursors, by interstellar chemistry.

Effect of tamoxifen on lumbar spine bone mineral density in postmenopausal women after 5 years

BACKGROUND

Because adjuvant tamoxifen citrate is given to women with early-stage breast cancer for long periods, it is important to know how it affects risk factors for osteoporotic bone fractures, particularly since rates of bone fracture increase rapidly with age in postmenopausal women. In a 2-year randomized placebo-controlled toxicity study in 140 subjects, we demonstrated that tamoxifen was associated with preservation of bone mineral density (BMD), a major risk factor for fractures, in the lumbar spine.

METHODS

Five years after entry on this study we reexamined 62 of the original subjects with lumbar spine BMD and serum osteocalcin measurements. These were women available for study because they had not suffered major illnesses and had continued to receive (1) tamoxifen or (2) the no-tamoxifen regimen that they had originally been randomized to receive for the entire 5 years.

RESULTS

For lumbar spine BMD at baseline, the 30 subjects in the long-term tamoxifen group and the 32 subjects in the long-term no-tamoxifen group were not significantly different (P = .26). During the first 2 years of follow-up, the 30 subjects in the long-term tamoxifen group showed the same BMD pattern as the entire 70-patient tamoxifen cohort, and similarly the 32 subjects in the long-term no-tamoxifen group showed the same pattern as the entire 70-patient cohort who received placebo. Five-year mean BMD measurements for each long-term follow-up group showed no significant changes from their respective 2-year levels. However, 5-year BMD measurements between the two groups differed (tamoxifen group, +0.8%; placebo group, -0.7%) (P = .06), and the mean regression lines for the changes in BMD over 5 years differed significantly between the two groups (P = .0005). Adjustment for differences in body mass index, reported exercise, and calcium supplementation between these two groups did not change these results. Osteocalcin levels, also comparable at baseline in the two groups, were significantly lower in tamoxifen-treated subjects at 5 years (P = .0005).

CONCLUSIONS

While remodeling of bone may be lower, resorption of lumbar spine bone mineral is also lower, and tamoxifen preserves BMD in the lumbar spine over 5 years of treatment in postmenopausal women. Over longer periods, this preservation of BMD might be expected to be associated with lower fracture rates.

Integration of the cognitive and the psychodynamic unconscious

Cognitive-experiential self-theory integrates the cognitive and the psychodynamic unconscious by assuming the existence of two parallel, interacting modes of information processing: a rational system and an emotionally driven experiential system. Support for the theory is provided by the convergence of a wide variety of theoretical positions on two similar processing modes; by real-life phenomena--such as conflicts between the heart and the head; the appeal of concrete, imagistic, and narrative representations; superstitious thinking; and the ubiquity of religion throughout recorded history--and by laboratory research, including the prediction of new phenomena in heuristic reasoning.

Utilization of cyclosporine H to elucidate the possible mechanisms of cyclosporine A-induced osteopenia in the rat

The immunosuppressive agent cyclosporine A (CsA) produces in vivo in the rat marked osteopenia and elevation of serum bone gla protein (BGP) that reflects the high bone turnover and increased circulating levels of 1,25-dihydroxyvitamin D [1,25(OH)2D]. Cyclosporine H (CsH), a D-N-MeVal11 analog of CsA, is not immunosuppressive, and in contrast to CsA, it neither binds to cyclophilin nor alters cytokine activity. This distinction between CsH and CsA provides a means of elucidating whether CsA exerts an effect on bone and 1,25(OH)2D via immune-mediated mechanisms. We therefore studied three groups of male Sprague-Dawley rats (300 to 350 g body weight [BW]) randomly divided to receive either cyclosporine vehicle, CsA, or CsH 15 mg/kg BW by daily gavage for 28 days. Blood samples were assayed for ionized calcium (Ca2+), serum BGP, serum parathyroid hormone (PTH), and 1,25(OH)2D by specific radioimmunoassay on days 0, 14, and 28. Histomorphometric evaluations were performed on the right tibia after tetracycline and calcein labeling and killing of the rats at the end of 28 days of treatment. In CsA-treated rats, serum BGP levels were significantly increased (155.2 +/- 30.7 ng/mL v 107.3 +/- 16.8 and 111.5 +/- 13.1 at day 28, P < .05) compared with control and CsH groups, respectively. Similarly, 1,25(OH)2D was significantly increased in CsA-treated rats versus control and CsH group (134.9 +/- 35.3 pg/mL v 70.2 +/- 16.6 and 69.8 +/- 20.6 [P < .05], respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Interferon-gamma causes loss of bone volume in vivo and fails to ameliorate cyclosporin A-induced osteopenia

Interferon-gamma (IFN gamma) in vitro inhibits both bone resorption and bone formation, resulting in a net decrease in bone turnover. In vivo administration of cyclosporin A (CsA) produces accelerated bone remodeling with resultant bone loss. The aim of this study was to investigate whether administration of IFN gamma to rats would favorably modify the high turnover osteopenia caused by CsA. Thirty-six male Sprague-Dawley rats were randomized into 4 equal groups to receive either CsA (15 mg/kg.day) or vehicle by gavage and IFN gamma (10(6) IU/kg.day) or vehicle by ip injection for 8 days. Group 1 received CsA vehicle plus IFN gamma vehicle; group 2 received CsA plus IFN gamma vehicle; group 3 received CsA vehicle plus IFN-gamma; group 4 received CsA plus IFN gamma. Blood was sampled on days 0, 4, and 8 for measurement of ionized calcium (Ca2+), PTH, 1,25-dihydroxyvitamin D, and bone gla protein. Tibiae were removed on day 8 after double tetracycline labeling for histomorphometric analysis. Ca2+ and PTH levels were similar in all groups during the study period. Rats receiving CsA (groups 2 and 4) had elevated levels of 1,25-dihydroxyvitamin D and bone gla protein, whereas rats receiving IFN gamma alone (group 3) had no change in levels of these parameters. Bone histomorphometry revealed that treatment with CsA and/or IFN gamma (groups 2-4) caused an increase in bone resorption surface and a decrease in some parameters of bone formation, resulting in a net loss of bone volume. Thus, IFN gamma failed to influence the osteopenia caused by CsA and on its own had adverse effects on bone in vivo. These results demonstrate that immune-mediating agents have opposing actions in vitro as compared to in vivo.

Climatic Implications of an 8000-Year Hydrogen Isotope Time Series from Bristlecone Pine Trees

Tree rings from three dendrochronologically dated bristlecone pines were analyzed for stable hydrogen isotopic composition. These trees give a continuous time series from 8000 years ago to the present that indicates the presence of a postglacial climate optimum 6800 years ago and a continuous cooling since then. The qualitative agreement between this record and records from other sources, such as ice cores, pollen, and treeline fluctuations, indicates that these climate changes were global. This record can serve as a reference for other climate indicators throughout the past 8000 years.

Integration of the cognitive and the psychodynamic unconscious

Cognitive-experiential self-theory integrates the cognitive and the psychodynamic unconscious by assuming the existence of two parallel, interacting modes of information processing: a rational system and an emotionally driven experiential system. Support for the theory is provided by the convergence of a wide variety of theoretical positions on two similar processing modes; by real-life phenomena--such as conflicts between the heart and the head; the appeal of concrete, imagistic, and narrative representations; superstitious thinking; and the ubiquity of religion throughout recorded history--and by laboratory research, including the prediction of new phenomena in heuristic reasoning.

Conflict between intuitive and rational processing: when people behave against their better judgment

When offered an opportunity to win $1 on every "win" trial in which they drew a red jelly bean, subjects frequently elected to draw from a bowl that contained a greater absolute number, but a smaller proportion, of red beans (e.g., 7 in 100) than from a bowl with fewer red beans but better odds (e.g., 1 in 10). Subjects reported that although they knew the probabilities were against them, they felt they had a better chance when there were more red beans. Similar, but less extreme results were obtained on "lose" trials, where drawing a red bean meant losing $1. These results were predicted from the concretive and experiential principles of cognitive-experiential self-theory. Nonoptimal choices in the laboratory were significantly correlated with heuristic responses to relevant vignettes and with self-reported gambling in real life.

Water on Mars: Clues from Deuterium/Hydrogen and Water Contents of Hydrous Phases in SNC Meteorites

Ion microprobe studies of hydrous amphibole, biotite, and apatite in shergottite-nakhlite-chassignite (SNC) meteorites, probable igneous rocks from Mars, indicate high deuterium/hydrogen (D/H) ratios relative to terrestrial values. The amphiboles contain roughly one-tentn as much water as expected, suggesting that SNC magmas were less hydrous than previously proposed. The high but variable D/H values of these minerals are best explained by postcrystallization D enrichment of initially D-poor phases by martian crustal fluids with near atmospheric D/H (about five times the terrestrial value). These igneous phases do not directly reflect the D/H ratios of martian "magmatic" water but provide evidence for a D-enriched martian crustal water reservoir.

Immunosuppressive therapy and the skeleton

Glucocorticoids and other immunosuppressive drugs, such as cytoclosporine A, are increasingly used today. One of the most common clinical situations in which they are prescribed is for immunosuppression after organ transplantation. These drugs have diverse effects on the skeleton, however, and one of the most common sequelae of organ transplantation is osteoporosis and fractures. Patients treated with immunosuppressive drugs should be carefully evaluated for osteoporosis, preferably prior to or at the time of initiation of immunosuppressive therapy. They should be followed carefully with sequential bone-density measurements and biochemical indices of bone turnover. Measures to prevent bone loss should be initiated early in the course of immunosuppressive therapy.

Conflict between intuitive and rational processing: when people behave against their better judgment

When offered an opportunity to win $1 on every "win" trial in which they drew a red jelly bean, subjects frequently elected to draw from a bowl that contained a greater absolute number, but a smaller proportion, of red beans (e.g., 7 in 100) than from a bowl with fewer red beans but better odds (e.g., 1 in 10). Subjects reported that although they knew the probabilities were against them, they felt they had a better chance when there were more red beans. Similar, but less extreme results were obtained on "lose" trials, where drawing a red bean meant losing $1. These results were predicted from the concretive and experiential principles of cognitive-experiential self-theory. Nonoptimal choices in the laboratory were significantly correlated with heuristic responses to relevant vignettes and with self-reported gambling in real life.

The deleterious effects of long-term cyclosporine A, cyclosporine G, and FK506 on bone mineral metabolism in vivo

Administration of cyclosporine A to male and female rats accelerates bone remodeling and causes bone loss, among other side-effects. The newer immunosuppressant drugs, FK506 and CsG, have been synthesized to counteract the toxic effects of CsA, yet maintain clinical efficacy. We investigated the in vivo effects of long-term administration of these drugs on bone mineral metabolism in the rat. Five groups of Sprague-Dawley rats, 15 per group, were allocated to receive by daily gavage for a period of 28 days: (1) Cs-vehicle; (2) CsA 15 mg/kg b.w.; (3) CsG 15 mg/kg b.w.; (4) FK506 vehicle; (5) FK506 5 mg/kg b.w. Blood was sampled on days 0, 14, and 28 for measurement of ionized calcium (Ca2+), parathyroid hormone (PTH), 1,25-(OH)2-vitamin D, and bone gla protein (BGP). Tibiae were removed on day 28 after double calcein labeling for histomorphometric analysis. Immunosuppressant groups were compared with the respective vehicle groups. Neither CsA or CsG affected the levels of Ca2+ or PTH, whereas by day 28 FK506 caused a decrease in Ca2+ and a corresponding rise in PTH (P < 0.05). The 1,25-(OH)2-vitamin D and BGP levels in both the CsA and CsG groups were increased on days 14 and 28 (P < 0.05), while FK506 had no effect on these serum levels. Tibial bone histomorphometry revealed that all 3 immunosuppressants increased measures of bone formation and bone resorption, accompanied by a significant reduction in percent trabecular area, most marked with FK506. This report demonstrates that all three immunosuppressants have adverse effects on bone--most deleterious with FK506.

Environmental risk factors for osteoporosis

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Effect of cyclosporin A on bone mineral metabolism in experimental diabetes mellitus in the rat

Cyclosporin A (CsA) is widely used in diabetic transplant patients and early type I diabetes mellitus. Diabetes produces a low-turnover osteopenia, and CsA conversely induces high-turnover osteopenia in rats. We investigated whether CsA would exacerbate diabetic osteopenia. Four groups of 10-week-old male Sprague-Dawley rats (n = 11/group) were studied: On day -6, groups A and C received saline and groups B and D received intravenous streptozotocin (55 mg/kg) to induce diabetes. From day 0, groups A and B received CsA vehicle and C and D received CsA (15 mg/kg) by daily gavage. Rats were bled on days -6, 0, 11, and 22 for serum bone gla protein (BGP), 1,25-(OH)2D, PTH, blood ionized Ca, and blood glucose determinations. Double tetracycline labeling was performed on days 9 and 20 for bone histomorphometry. After sacrifice on day 22, histomorphometric analysis was performed. Serum BGP, 1,25-(OH)2D, and PTH levels were significantly decreased in the diabetic alone (B) and diabetic plus CsA (D) groups and significantly increased in the CsA alone (group C). CsA alone (group C) induced cancellous bone loss by stimulated bone resorption. Cancellous bone loss in the diabetic alone rats (group B) was caused primarily by inhibited bone formation. No differences were found in cancellous bone mass, formation, or resorption parameters between diabetic alone (group B) and CsA-treated diabetic rats (group D). Neither CsA alone (group C) nor diabetic alone (group B) nor their combination affected cortical bone mass. CsA alone (group C) stimulated periosteal bone formation and endocortical bone resorption and inhibited endocortical formation, and diabetic alone (group B) inhibited both periosteal and endocortical bone formation. No parameters of tibial diaphyses in CsA-treated diabetic rats (group D) were different from diabetic alone. Thus the addition of CSA to the diabetic treated rats (group D) could not stimulate remodeling and appeared not to worsen significantly some of the alterations in bone formation and resorption. Possible explanations for this may be that CsA in vivo requires adequate levels of PTH, 1,25-(OH)2D, insulin, and perhaps growth factors to stimulate remodeling. The use of CsA in type I diabetic patients or in organ transplant recipients who remain diabetic after transplantation may in the short term not aggravate existing osteopenia based on these findings.

Signal-averaged electrocardiography in elderly subjects with and without heart disease

Prevalence of abnormal signal-averaged electrocardiography in normal populations appears to be low, but has not been studied previously in an asymptomatic elderly population. To study the prevalence of abnormal ventricular late potentials in an elderly population, a group of 51 subjects with no evidence of cardiac disease and ranging in age from 62 to 102 years underwent signal-averaged electrocardiography. Results were compared to a group of 179 patients similar in age but with complex ventricular arrhythmias, and to a group of 25 asymptomatic volunteers under the age of 50. The prevalence of an abnormal signal-averaged ECG was 14% in the normal elderly subjects, and 31% in the patients (P = 0.01), and 4% in the young subjects (P = NS). We conclude that the prevalence of abnormal ventricular late potentials in elderly patients without heart disease is similar to levels reported in other populations of normal controls, but elderly patients with cardiac disease have a significantly higher prevalence of abnormal signal-averaged ECG studies than the normals.

Influence of age on cyclosporin A-induced alterations in bone mineral metabolism in the rat in vivo

Cyclosporin A (CsA) administered to actively growing young rats produces a high-turnover osteopenia. We investigated and compared the effect of CsA on the bone mineral metabolism in young rats with that of older rats, which have a lower rate of bone turnover. A group of 24 young (9 weeks) and 24 older (9 months) male Sprague-Dawley rats were orally administered 15 mg/kg of CsA or placebo daily for 24 days. Rats were weighed and serum assayed serially for bone gla protein (BGP), parathyroid hormone, ionized calcium, blood urea nitrogen, creatinine, and 1,25-dihydroxyvitamin D [1,25-(OH)2D]. After sacrifice, histomorphometric analysis was performed on undecalcified proximal tibial metaphysis with double-fluorescent labeling. Serum BGP levels were significantly elevated in both young and older rats administered CsA, and 1,25-(OH)2D levels were significantly elevated in CsA-treated young rats more than in older rats. Body weight was significantly reduced in CsA-treated older rats. There were mild but significant alterations in renal function in both groups receiving CsA. In the most comprehensive examination to date of the effects of CsA on bone histomorphometry, both young (-44%) and older rats (-20%) lost significant amounts of trabecular bone compared to their respective controls. Bone loss in young rats was mainly due to a reduced number of trabecular; older rats lost mainly trabecular thickness. Microanatomic nodal studies were consistent with these results. These data demonstrate that although cancellous bone loss induced by CsA is more marked in young rats, older rats with slower bone turnover are also at risk.

[Computer-assisted surgery documentation in clinical routine practice]

In surgery, computer support is still of minor importance. It is the aim of this publication to outline the concept of a computer-assisted documentation system for surgical procedures, to describe the realization of the concept and to discuss the results of the evaluation. Planning of the system started in 1988 with an analysis of existing computer support at our clinic, definition of the parameters to be documented and determination of the classifications to be used, followed by a design for the system's use and a decision on hardware and software. The system is run on an IBM-compatible personal computer with three terminals, and the software used is MEDOS. The surgical procedures are documented with a four-level hierarchical classification related to the VESKA code and the internal university codes. After extensive training of the doctors, routine use commenced in 1991. Up to now 9837 operations have been documented by 35 surgeons. The system produces all necessary statistics and supports scientific studies and inquiries from individual doctors. A prospective evaluation of 300 consecutive operations demonstrated good compliance of the doctors and high data quality. To achieve optimal benefit from the use of computers it is recommended that departmental communication and documentation systems be gradually built up in surgical departments.

Molecular and isotopic analyses of the hydroxy acids, dicarboxylic acids, and hydroxicarboxylic acids of the Murchison meteorite

The hydroxymonocarboxylic acids, dicarboxylic acids, and hydroxydicarboxylic acids of the Murchison meteorite were analyzed as their tert-butyldimethylsilyl derivatives using combined gas chromatography-mass spectrometry. The hydroxydicarboxylic acids have not been found previously in meteorites. Each class of compounds is numerous with carbon chains up to C8 or C9 and many, if not all, chain and substitution position isomers represented at each carbon number. The alpha-hydroxycarboxylic acids and alpha-hydroxydicarboxylic acids correspond structurally to many of the known meteoritic alpha-aminocarboxylic acids and alpha-aminodicarboxylic acids, a fact that supports the proposal that a Strecker synthesis was involved in the formation of both classes of compounds. Isotopic analyses show these acids to be D-rich relative to terrestrial organic compounds as expected; however, the hydroxy acids appear to be isotopically lighter than the amino acids with respect to both carbon and hydrogen. The latter finding would not be expected if both classes of compounds came exclusively from common precursors as would have been the case for a Strecker synthesis.

Lack of change of cancellous bone volume with short-term use of the new immunosuppressant rapamycin in rats

Immunosuppressants have adverse effects on bone mineral metabolism in animal and human studies, with corticosteroids producing low-turnover osteopenia, and cyclosporin-A (CsA) producing high-turnover osteopenia. Rapamycin (RAPA) is a new immunosuppressant reported to be at least 10 times more potent than CsA, and acts via a different pathway to CsA and the other new immunosuppressant FK506. This study investigated the effects of RAPA on bone mineral metabolism in the rat. Forty-two, 10-week-old, male Sprague Dawley rats were divided into three groups, and treated according to the following protocol: group A (control) received RAPA vehicle by daily gavage for 14 days (n = 12); group B (high dose RAPA) received RAPA 2.5 mg/kg/day by daily gavage for 14 days (n = 15); group C (low dose RAPA) received RAPA 1.25 mg/kg/day by daily gavage for 14 days (n = 15). Rats were weighed and bled on days 0, 7, and 14 for measurement of blood ionized calcium, bone Gla protein (BGP), parathyroid hormone (PTH), and 1,25(OH)2D. Tibial bone histomorphometry was determined on day 14 after double-calcein labeling. Weight gain was similar in the two groups treated with RAPA compared with control animals. High-dose RAPA (group B) transiently depressed serum BGP levels on day 7, with elevated blood ionized calcium levels on day 7, and lowered 1,25(OH)2D levels on day 14. Serum PTH levels were unchanged. Low-dose RAPA (group C) did not affect calciotropic hormones.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of general hospitals in the privatization of inpatient treatment for serious mental illness

For almost three decades, many have regarded general hospital psychiatric units as the most appropriate setting for acute treatment of persons with serious mental illness who were once treated mostly in state hospitals. The extent to which this transfer has taken place and the differences between public and private general hospitals have been unclear. Using data from the 1988 National Mental Health Facilities Study and published data from the 1970s, the authors found that nearly half of all general hospitals providing psychiatric services treat persons with serious mental illness. Significant differences in case and payer mix were observed between public and private general hospitals, although these differences were smaller than in the 1970s. The findings suggest increased involvement by private general hospitals in treating patients reimbursed by public payers, but the findings also indicate that persons with serious mental illness and those using Medicaid are still more prevalent in public general hospitals than in private ones.