[Therapeutic concepts in the treatment of postmenopausal osteoporosis]

Postmenopausal osteoporosis is not a well-defined disease, but summarizes women with different severity of changes in bone metabolism and different clinical complaints. The only common feature in women with 'postmenopausal osteoporosis' is the deficiency of estrogen. Postmenopausal women can be subdivided into four groups, according to their risk for fractures: 1. women without evident increase of fracture risk (bone mineral content between 0 and 2 SD of age-related normal range, no known risk factors from history); 2. women with possible increase of fracture risk (bone mineral content between 0 and -2 SD of age-related normal range, with or without known risk factors from history); 3. women with clear increase of fracture risk (bone mineral content below age-related normal range, with or without known risk factors from history); 4. women with already occurred fracture (manifest osteoporosis). Therapeutic intervention in postmenopausal women should be adapted to the risk for fracture. In all four groups a secondary prevention or basic therapy should be performed, focusing on calcium intake, vitamin D supply and sufficient physical activity. Calcium intake should be 1500 mg/day in women without estrogen substitution and 1000 mg in women with estrogen substitution. In patients living mainly inside or with malnutrition, a daily substitution of 500 E. Vitamin D3 is recommended. In group 2, regular control of bone mass is recommended to start additional estrogen replacement therapy, if accelerated loss of bone mass occurs. In group 3, estrogen replacement therapy is recommended urgently and is the therapy of first choice to prevent development of fractures. In group 4 (manifest osteoporosis), therapy should aim on improvement of the patient's symptoms and on increase of bone stability to avoid further fractures. The symptomatic therapy includes pain medications and an intensive physical therapy adapted to the patient's needs. Physical therapy should be performed for long time to reduce complaints and to improve musculoskeletal function in order to prevent falls. Different agents influencing bone metabolism by inhibition of bone resorption (estrogens, calcitonin, bisphosphonates) or stimulation of bone formation (fluoride) are used in manifest osteoporosis to increase bone stability. But the present efficacy to avoid further fractures has not been shown sufficiently for all available agents, so that a final evaluation and recommendation can't be done. Therapy decisions in manifest osteoporosis are often influenced by the possible side effects of the drugs (bleeding, gastrointestinal problems, joint pain), other, not bone-related effects of the drugs (improvement of climacteric complaints, pain relief) and other concomitant diseases and medications.

Differential effects of 1,25-dihydroxyvitamin D3 on cell proliferation and calcitonin gene expression

1,25-Dihydroxyvitamin D3 (1,25D3) inhibits cell growth and induces differentiation in many cell systems by inhibition of c-myc gene expression. In the human medullary thyroid carcinoma cell line (TT), c-myc gene expression appears to be closely related to cell proliferation and differentiation. TT cells are also a well known target system for 1,25D3, which inhibits calcitonin (CT) gene expression in these cells. So far, no direct cis-acting vitamin D-responsive element could be identified in the promoter region of the CT gene. We, therefore, investigated potential indirect mechanisms of 1,25D3-mediated CT gene expression by examining the hormone's effects on proliferation. In contrast to its well established antiproliferative action in other cell systems, addition of 1,25D3 to TT cells led to a 2.3-fold stimulation of DNA synthesis, which was maximal after 48 h and was preceded by a 4.8-fold increase in c-myc gene expression. c-Myc antisense DNA oligomers abolished the proliferative effect of 1,25D3, but not the latter's inhibition of CT gene expression. Here we present evidence that activation of c-myc gene expression mediates 1,25D3-stimulated TT cell proliferation, but not the 1,25D3-induced inhibition of CT gene expression.

[Osteoporosis]

Liver cirrhosis may be accompanied by osteoporosis and, rarely, osteomalacia. Normal liver function is required for normal digestion and absorption of calcium-containing nutrients. The liver plays an important role for the metabolisation of vitamin D: the 25-hydroxylation takes place in the liver. However, the respective enzymatic capacity is not limited by liver diseases except for almost complete liver insufficiency. Therefore, true hypovitaminosis D only rarely plays a role in hepatic osteopenia, but direct toxic effects on bone forming cells (osteoblasts) are discussed: e.g. by bile salts. Coexisting hypogonadism leads to further bone loss. Patients with primary biliary cirrhosis in part present with osteoporosis and fractures. Bone histology reveals normal resorption, but decreased formation. Calcitropic hormones are generally normal. Chronic alcoholism induces the same histologic picture in bone, i.e. normal resorption and diminished formation. These changes are reversible after abstinence and as long as of cirrhosis has not yet developed. Patients undergoing liver transplantation due to end stage liver insufficiency including cirrhosis present with diminished bone mass before receiving a new liver, and they show further bone loss after the transplantation due to immunosuppressive treatment including glucocorticoids. There is no specific treatment of bone loss or osteoporosis due to liver cirrhosis. Preventive efforts should be devoted to the avoidance of suboptimal calcium and vitamin D supply, immobilization, and hypogonadism. Fluorides may increase bone mass after liver transplantation--perhaps they are also useful in liver cirrhosis. Antiresorption agents like calcitonins or bisphosphonates may be cautiously tried.

Tissue factor controls the balance of angiogenic and antiangiogenic properties of tumor cells in mice

Meth-A sarcoma cells were stable transfected to overexpress (sense construct) or underexpress (antisense construct) tissue factor. In vitro, there was no difference in plating efficiency or growth between these cell lines. In vivo, tumor cells transfected to overexpress tissue factor grew more rapidly, and established larger and more vascularized tumors than control transfectants. Antisense transfectants grew the slowest and were the least vascularized. Anticoagulation of mice with warfarin did not alter the difference between these tumor lines. Tumor cells over-expressing tissue factor released more (compared with control transfectants) mitogenic activity for endothelial cells in parallel with enhanced transcription of vascular permeability factor/vascular endothelial cell growth factor (VEGF/VPF), and diminished transcription of thrombospondin (TSP2), a molecule with anti-angiogenic properties. Antisense tissue factor transfectants, while releasing the lowest amount of mitogenic activity, had increased thrombospondin and decreased VEGF/VPF transcription compared with control transfectants or wild-type cells. Experiments with these sense, antisense, truncated sense, or vector tumor lines gave comparable results in complete medium, serum free medium or in the presence of hirudin, indicating that the activation of the coagulation mechanism was not likely to be responsible for changes in tumor cell properties. These results suggest that tissue factor regulates angiogenic properties of tumor cells by altering the production of growth regulatory molecules of endothelium by a mechanism distinct from tissue factor activation of the coagulation mechanism.

Elevated thrombomodulin plasma levels as a result of endothelial involvement in plasmodium falciparum malaria

We used thrombomodulin (TM) to assess the participation of the vascular endothelium in human Plasmodium falciparum (P.F.) malaria. Before therapy TM plasma levels were elevated in P.F. malaria and fell to normal values during therapy. Parasitemia, TNF alpha, elastase and TAT levels correlated directly with TM. Elevated TM levels can not be explained by increased synthesis, since incubating HUVEC with pretherapy serum of patients with P.F. malaria, but not reconvalescence serum, suppressed TM transcription. This was partially prevented by adding a TNF alpha neutralizing antibody to patient serum before incubation with HUVEC. However, TNF alpha does not release TM from cultured HUVEC in vitro. Coincubation of HUVEC with pretherapy serum together with neutrophils resulted in endothelial cell destruction, which could be partly prevented by a TNF alpha neutralizing antibody. Hence the increase of TM during P.F. malaria might reflect the concerted action of cytokines and neutrophils on HUVEC.

Urinary hydroxypyridinium crosslinks of collagen in population-based screening for overt vertebral osteoporosis: results of a pilot study

The urinary pyridinium crosslinks pyridinoline (PYD) and deoxypyridinoline (DPD) have been shown to provide valid indices of bone resorption. At present, both crosslink components are determined by reversed-phase HPLC, a time-consuming method precluding the use of these markers for routine purposes. Therefore, efforts have been made to develop simple immunoassays for the rapid measurement of urinary crosslinks, and their application to large-scale osteoporosis screening has been proposed. To evaluate the applicability and diagnostic validity of pyridinium crosslink measurements for screening purposes, urinary concentrations of total and free PYD and DPD were determined by HPLC and immunoassay technique (ELISA) in a sample of 269 individuals (male to female ratio = 130:139; age 50-81 years) recruited at random within a population survey of vertebral osteoporosis. On a molar basis, ELISA measures of crosslink-related epitopes were highly correlated with both total and free PYD and DPD as determined by HPLC (r > 0.82, p < 0.001). Age-specific means for creatinine-corrected total and free pyridinium crosslinks were significantly higher in females than in males (p < 0.001). In both sexes, neither age nor anthropometric variables (weight, height, and body mass index) showed a linear effect on the urinary crosslink/creatinine ratio. On average, 50% of the total amount of urinary crosslinks were present in free form. For both PYD and DPD, this proportion was significantly higher in women than in men (p < 0.05), but no change was observed with age or anthropometric measures. The excretion of pyridinium crosslinks was higher in osteoporotic (n = 18) than in nonosteoporotic individuals (n = 208) from the same population.(ABSTRACT TRUNCATED AT 250 WORDS)

Forearm BMD as measured by peripheral quantitative computed tomography (pQCT) in a German reference population

Low bone mass as estimated by decreased bone mineral density (BMD) is an established predictor of osteoporotic fractures. One of the latest developments in bone densitometry is peripheral quantitative computed tomography (pQCT) of the forearm. In Germany, the CT bone scanner XCT 900 has already been widely used; however, interpretation of measurements with respect to osteoporosis risk assessment can be improved by better defined and validated reference data. In the present study, this device was used to measure BMD at the distal radius in a well-defined healthy population of 179 German adults (91 men, 88 women) aged 20-79 years. In vivo precision was 1.67% for trabecular and 0.81% for total BMD measurements. Peak values of trabecular and total BMD were observed at the ages 40-50 years in women and 30-40 years in men. Beyond these ages, both trabecular and total BMD showed a linear decline with age, decreasing by 0.85% and 1.08% per year in women and by 0.59% and 0.54% in men, respectively. Measures of BMD were not influenced by weight, height or body mass index (BMI). In both sexes, trabecular and total radial BMD showed a positive and significant correlation with femoral BMD measures obtained by dual X-ray absorptiometry (DXA). Weaker correlations were observed with DXA measures of the lumbar spine. Compared with the 95% reference range provided by the manufacturer, the distribution of age- and sex-specific values of trabecular BMD of the distal radius was shifted to lower values by up to 1 standard deviation.(ABSTRACT TRUNCATED AT 250 WORDS)

Defensive use of an acquired substance (carminic acid) by predaceous insect larvae

Larvae of two insects, a coccinellid beetle (Hyperaspis trifurcata) and a chamaemyiid fly (Leucopis sp.), feed on cochineal insects and appropriate their prey's defensive chemical, carminic acid, for protective purposes of their own. H. trifurcata discharges the chemical with droplets of blood (hemolymph) that it emits when disturbed; Leucopis sp. ejects the compound with rectal fluid. Ants are thwarted by these defenses, which are compared with the previously-described defense of a pyralid caterpillar (Laetilia coccidivora) that disgorges carminic acid-laden crop fluid. The defensive fluid of all three larvae contains carminic acid at concentrations spanning a range (0.2-6.2%) proven deterrent to ants. Many insects are known to appropriate defensive substances from plants. Insects that acquire defensive chemicals from animal sources may be relatively rare.

Comparison of a semiquantitative and a quantitative method for assessing vertebral fractures in osteoporosis

There is no agreed definition for the assessment of vertebral fractures and deformities in patients with osteoporosis. Radiographs of 66 patients randomized for therapy with etidronate or placebo were analyzed at baseline and during follow-up (60/120/150 weeks) independently using two procedures. The first method of spinal deformity index (SDIG) and vertebral deformity score (VDSG) is based on a semiquantitative visual reading of each vertebra between T4 and L4. The second method of spine deformity index (SDIM) and vertebral deformity index (VDIM) is based on vertebral height measurements of T4 through L5 and each measurement from T5 to L5 (anterior, middle and posterior height) is related to T4 and compared with the respective T4-related normal range. There was good agreement between the mean vertebral deformation from T5 to L4 graded by VDSG and VDIM, with correlation coefficients between R = 0.52 (p < 0.0001) and R = 0.9 (p < 0.0001) respectively. Spinal deformation at baseline as measured by SDIM and SDIG was correlated with R = 0.76 (p < 0.0001). For diagnosing a vertebra as fractured or not, VDIM reached a sensitivity of 82% and a specificity of 85% using VDSG as a standard, and on the other hand VDSG reached a sensitivity of 78% and a specificity of 88% in relation to VDIM. The changes in spinal deformation from week 0 to 150 were correlated with R = 0.58 (p < 0.0002) between SDIM and SDIG. To detect vertebral fracture progression the sensitivity of VDIM was 74% and the specificity 86%, when changes in VDSG were used as a standard.(ABSTRACT TRUNCATED AT 250 WORDS)

Parathyroid hormone-related protein and life expectancy in hypercalcemic cancer patients

We determined the effect of raised serum levels of midregional (53-84) parathyroid hormone-related protein (PTHrP) on life expectancy in 59 cancer patients with first presentation of hypercalcemia. The patients were stratified according to the serum PTHrP levels measured on day 0 after fluid repletion prior to bisphosphonate therapy. Twenty-nine patients were assigned to group N (PTHrP < or = 21 pmol/L) and 30 to group E (PTHrP > 21 pmol/L). Breast cancers were more common in group N, squamous cell cancers predominated in group E (p < 0.02). More patients with normal PTHrP had skeletal metastases, whereas group E was characterized by a higher incidence of prognostically unfavorable visceral involvement (p < 0.001). Bisphosphonates (pamidronate or BM.210955) were administered on day 0. Within one week, normocalcemia (serum calcium < or = 2.6 mmol/L) was restored in 96% of patients in group N, compared to 70% of patients in group E (p < 0.01). On day 12, 7 patients with elevated PTHrP were still hypercalcemic. Although a comparable number of patients in the two groups received cytostatic treatment after day 12, objective tumor responses were seen only in group N (n = 6; p < 0.05). Calculated from the first occurrence of hypercalcemia, the median survival was 66 days in group N and 33 days in group E (log-rank test: p = 0.0456; Wilcoxon-Breslow test: p = 0.0475). We conclude that in hypercalcemia of malignancy raised serum levels of PTHrP indicate a reduced hypocalcemic response to bisphosphonates, a more advanced tumor state and, therefore, an extremely poor prognosis.

Apolipoprotein (a) phenotypes and lipoprotein (a) concentrations in patients with type III hyperlipoproteinaemia

OBJECTIVES

The familial lipoprotein disorder type III hyperlipoproteinaemia (HLP) carries a marked increase in the risk of accelerated and premature atherosclerosis, but there is considerable variation amongst affected individuals in their susceptibility to cardiovascular disease (CVD). Therefore, it was the aim of our study to investigate the possible influence of lipoprotein (a) [Lp(a)] in the pathogenesis of type III HLP:

DESIGN

Apolipoprotein (a) [apo(a)] phenotypes and Lp(a) concentrations were determined in patients with the disease and in an appropriate control group.

SETTING

University out-patient lipid disorder clinic.

SUBJECTS

Seventy-six apoE-2 homozygous patients with type III HLP and 76 normolipidaemic and healthy age- and sex-matched controls.

MAIN OUTCOME MEASURES

The frequencies of different apo(a) phenotypes and their correlations with Lp(a) serum concentrations were determined in patients and controls.

RESULTS

Lp(a) concentrations were not significantly different in type III HLP patients (14.1 +/- 19.1 mg dl-1) as compared with the controls (13.3 +/- 16.2 mg dl-1; P = 0.549, NS). In addition, there was no significant difference in apo(a) phenotype frequencies amongst both groups (0.2 > P > 0.1).

CONCLUSIONS

We conclude that the apo(a) polymorphism does not participate (to a significant extent) in the phenotypical expression of type III HLP:

[Neutralizing antibodies against salmon calcitonin. The cause of a treatment failure in Paget's disease]

A 72-year-old woman with Paget's disease of the femur (increasing curvature of the femur in the last 20 years, lately with ever more pain on walking) was at first treated with salmon calcitonin, daily 400 IU nasally, for 2 years. As a result, alkaline phosphatase (AP) concentration fell from initially 703 U/l, to 401 U/l after 7 months' treatment. An increase in AP concentration was first noted after 10 months of treatment, rising after 24 months to 688 U/l. The symptoms, initially having responded rather well to therapy, markedly progressed. In parallel, titres were recorded for binding (maximally 1:100) and neutralizing antibodies (neutralizing action maximally 75%) against salmon calcitonin. Because of the development of secondary resistance to salmon calcitonin the medication was changed to human calcitonin (100 IU daily, subcutaneously). This again resulted in a fall of the AP concentration (to 319 U/l), which remained essentially unchanged (401 U/l) over a period of 17 months on 100 IU human calcitonin three times weekly.

Vascular origin of Kaposi's sarcoma. Expression of leukocyte adhesion molecule-1, thrombomodulin, and tissue factor

We studied seven cases of Kaposi's sarcomas (KS) obtained from patients with AIDS and one KS from a patient without HIV infection. Antigen expression was studied by immunocytochemistry and mRNA expression by in situ hybridisation. The markers tested were endothelial leukocyte adhesion molecule-1, thrombomodulin, and tissue factor. In all tumors (AIDS and non-AIDS associated) these markers reacted positive, indicating transcription and translation of these genes in KS. The synthesis and expression of tissue factor and thrombomodulin suggests that KS is a tumor that has tissue factor-mediated thrombin formation under the control of thrombomodulin. The expression of thrombomodulin and endothelial leukocyte adhesion molecule-1 provides evidence for the vascular origin of KS.

Osteoporosis will never be a disease of the past

There is a definite hope to considerably reduce the number of osteoporotic fractures in the future. However, there are several reasons to assume that osteoporosis as a disease will remain a problem in the future: (1) the population is aging, and many people will live long enough to develop a bone mineral density lower than the fracture threshold; (2) the secular trend shows that more handicapped people reach the 'fracture age'; (3) osteoporosis may develop in spite of adequate treatment; (4) prophylaxis with HRT is limited by lower compliance at older age. Efficient treatment strategies should therefore be developed for osteoporosis with fractures also in the future.

The ABCD (Appropriate Blood Pressure Control in Diabetes) trial. Rationale and design of a trial of hypertension control (moderate or intensive) in type II diabetes

OBJECTIVE

The primary objective of the ABCD (Appropriate Blood Pressure Control in Diabetes) Trial is to determine the efficacy of intensive versus moderate antihypertensive control on the outcome of type II diabetic end-organ complications in normotensive and hypertensive populations. The secondary objective is to determine whether any differential effect on end-organ complications exists between an angiotensin converting enzyme inhibitor (enalapril) and a calcium channel blocker (nisoldipine).

DESIGN

The ABCD Trial is a prospective, controlled, randomized, double-blind trial, with a planned follow-up of 5 years.

SETTING

All patients are seen at the Colorado Prevention Center, site of the ABCD Trial, for follow-up visits.

PATIENTS

Patients are type II diabetic males and females between the ages of 40 and 74 years with entry diastolic blood pressures > or = 80 mmHg. Patients were recruited from University of Colorado-affiliated hospitals, several health maintenance organizations, and mailing lists from the Colorado affiliate of the American Diabetes Association.

INTERVENTIONS

Patients were randomized to intensive antihypertensive drug therapy or moderate antihypertensive drug therapy. Patients were also randomized to nisoldipine or enalapril, with open-label medications added if further blood pressure control was necessary.

MAIN OUTCOME MEASURES

The primary outcome measure is glomerular filtration rate as assessed by 24-hour creatinine clearance. Secondary outcome measures are microalbumin urinary excretion, left ventricular hypertrophy, retinopathy, and neuropathy. Cardiovascular morbidity and mortality will also be evaluated.

CONCLUSION

Given the data showing the impact of hypertension on diabetic complications, the ABCD Trial was designed to determine if intensive antihypertensive therapy will be more efficacious than moderate antihypertensive therapy on the outcome of these complications. Results from the ABCD Trial are expected to lend interpretable and clinically relevant findings with regards to the treatment of hypertension in type II diabetes.

Long-term exposure to SMS 201-995 inhibits proliferation and calcitonin release in neoplastic C-cells

The effect of the long-acting somatostatin analogue SMS 201-995 on cellular proliferation and calcitonin production was examined in rMTC 6-23 cells. A dose-dependent inhibition of calcitonin release and cellular calcitonin content was obtained in cells exposed to SMS 201-995 for 72 hrs. The dose-dependent antiproliferative effect of SMS 201-995 (10(-8)-10(-6) M) was significant after 72 hrs of exposure. SMS 201-995 has an inhibitory effect on calcitonin secretion and synthesis as well as on the growth of C-cells.

Formation of neutralizing antibodies after treatment with human calcitonin

PURPOSE

Calcitonin is used for the treatment of Paget's disease of bone, hypercalcemia, and postmenopausal osteoporosis. The formation of antibodies against heterologous calcitonins, such as salmon calcitonin (sCT), has been described frequently. Neutralizing effects of these antibodies have been demonstrated in many cases. As far as antibody formation against human calcitonin (hCT) is concerned, only a single case has been reported in the literature; however, investigations concerning the biologic activity of the antibodies were not performed. We have now assessed the sera of 33 patients treated with hCT for postmenopausal osteoporosis for a period of at least 12 months to evaluate the occurrence of hCT-binding and hCT-neutralizing antibodies.

PATIENTS AND METHODS

Binding antibodies were detected by incubation of patient sera with 125I-labeled hCT; neutralizing activity was assessed in an in vitro bioassay that measured the impairment of the hCT-induced cyclic adenosine monophosphate (cAMP) formation in the human breast cancer cell line T47D.

RESULTS

Prior to hCT treatment, none of the patients showed evidence of the presence of either binding or neutralizing antibodies. During the course of treatment, binding antibodies occurred in a single patient. These antibodies had a neutralizing activity characterized by 15% impairment of cAMP formation after 6 months and 27% impairment after 12 months of treatment compared with pretreatment control values. The neutralizing effect observed in this particular patient was comparatively mild compared with the effects seen after the formation of neutralizing antibodies against sCT, so major clinical sequelae were not expected in this patient. This may be due to the lower antigenicity of hCT as compared with sCT.

CONCLUSION

Although antibody formation against hCT is a rare phenomenon, we nonetheless recommend monitoring of postmenopausal osteoporosis patients treated with sCT or hCT for neutralizing antibody formation in order to evaluate the therapeutic effect of treatment.