Differential action of the bisphosphonates (3-amino-1-hydroxypropylidene)-1,1-bisphosphonate (APD) and disodium dichloromethylidene bisphosphonate (Cl2MDP) on rat macrophage-mediated bone resorption in vitro.

The bisphosphonates (3-amino-1-hydroxypropylidene)-1,1-bisphosphonate (APD) and disodium dichloromethylidene bisphosphonate (Cl(2)MDP) effectively inhibit the accelerated bone resorption associated with some skeletal disorders, e.g., Paget's disease. However, it has not been established whether these compounds exert their inhibitory effect by rendering the bone mineral more resistant to degradation, by diminishing the activity of resorbing cells, or through some combination of both activities. In this study, we have tested these possibilities using an in vitro resorption assay system consisting of elicited rat peritoneal macrophages co-cultured with particles of (45)Ca-labeled, devitalized rat bone. This assay system permits the quantitative assessment of the action of APD and Cl(2)MDP on the two major phases of bone resorption (cell-substrate attachment and osteolysis) under circumstances where the drugs are present continuously or, most importantly for the issues in question, after the separate pretreatment of the particles or the resorbing cells. Our data indicate that (a) Both APD and Cl(2)MDP at concentrations >/=5 x 10(-6) M diminish macrophage-mediated (45)Ca release (i.e., bone resorption) in a log dose-dependent fashion. (b) A 10-min pretreatment of bone particles with either bisphosphonate (P-C-P) similarly inhibits resorptive activity, but is most pronounced with Cl(2)MDP. However, only APD is effective in reducing resorption when cells are preincubated (for 24 h) with P-C-P. (c) In cultures containing both labeled and unlabeled bone, significant inhibition occurs only when the labeled particles are coated with P-C-P (indicating that the action of P-C-P-treated bone is highly localized). (d) P-C-P does not diminish cell-bone particle attachment, an essential step in the resorptive process. On the other hand, delaying the addition of P-C-P until after cell-bone attachment is completed significantly reduces the resorption-inhibiting effect of these compounds. (e) Cl(2)MDP reduces culture DNA content in proportion to its inhibitory effect on resorption, and both the inhibitory and cytotoxic actions of this P-C-P are dependent upon the presence of bone. On the other hand, APD is cytotoxic only at very high concentrations (10(-4) M), acts independently of the presence of bone, and inhibits resorption without killing cells. We conclude that the mechanisms of action of APD and Cl(2)MDP are markedly different. Cl(2)MDP is a potent cytotoxin in the presence of bone and apparently exerts its inhibitory effect in this manner. APD is noncytotoxic at levels adequate to suppress resorption and, therefore, must inhibit macrophage activity by some other mechanism. Neither P-C-P appears to limit resorption by decreasing the solubility of mineralized bone matrix.

Modulation of the production of a parathyroid hormone-like protein in human squamous carcinoma cell lines by interaction with fibroblasts.

Normal human keratinocytes as well as human squamous cell carcinomas produce a parathyroid hormone-like protein (PLP). However, PLP production by these cells is not a constant phenomenon. Since nothing is known about factors which regulate the production of PLP, in vitro studies were performed with normal keratinocytes and squamous carcinoma cell lines in order to establish conditions under which PLP production may vary. PLP was measured as cyclic AMP production in parathyroid hormone target cells (osteoblasts) which could be inhibited by a parathyroid hormone antagonist. The presence of PLP was confirmed using a radioimmunoassay specific for PLP. Results from the bioassay correlated very well with the data obtained by radioimmunoassay for PLP. The results confirm that human squamous carcinoma cells and normal keratinocytes produce PLP. PLP production appeared to be very sensitive to modulation of coculture of squamous carcinoma cells with fibroblasts. The effect of fibroblasts was not mediated by an effect on squamous carcinoma cell viability. Murine transformed fibroblasts (3T3 cells) as well as human normal foreskin fibroblasts were equally effective in inducing PLP production in these cells. The fibroblastic factor was apparently present in a soluble form in the coculture system which prevented direct cell-cell contact but allowed communication through the medium. Nevertheless, conditioned medium from 3T3 cells failed to induce PLP production by squamous carcinoma cells. This suggests a more complicated interaction between the two cell types than a one way message from fibroblasts to keratinocytes. Production of PLP by a number of squamous carcinoma cell lines was variable and not evidently correlated with the ability of these carcinoma cells to differentiate. Production of parathyroid hormone-like protein not only is the expression of a disturbed metabolism of a specific cell type but also reflects the cell-cell interaction in tumor tissue.

Treatment of malignancy-associated hypercalcemia with intravenous aminohydroxypropylidene diphosphonate.

Treatment of malignancy-associated hypercalcemia remains unsatisfactory. We have prospectively treated 26 consecutive hypercalcemic cancer patients with intravenous (IV) aminohydroxypropylidene diphosphonate (APD). The drug was administered daily as a 15-mg two-hour IV infusion until both serum and urinary calcium had been normalized for 48 hours. Twenty-four patients were fully evaluable (eight head and neck tumors, seven breast cancers, three epidermoid tumors of the lung, and six miscellaneous neoplasms). Whereas rehydration had only inconsistent effects, APD normalized serum calcium in all patients after a mean of three daily doses: serum calcium decreased from 13.3 +/- 0.4 mg/dL (mean +/- SEM) before APD to 8.0 +/- 0.1 mg/dL at the end of treatment. Ionized calcium declined in parallel to total calcium. APD was as effective in hypercalcemia due to bone metastases as in paraneoplastic hypercalcemia. The drug was tolerated without toxicity and had a prolonged effect: serum calcium remained normal during 3+ weeks (1 + to 8 +) in 17 patients who did not receive or did not respond to antitumoral treatment. APD normalized serum calcium by inhibiting bone resorption, as evidenced by the dramatic decrease in urinary excretion of calcium and hydroxyproline. Inhibition of bone resorption was probably also responsible for the decrease in serum phosphorus from 2.9 +/- 0.2 to 2.0 +/- 0.1 mg/dL. In summary, IV APD constitutes a major advance in the treatment of malignancy-associated hypercalcemia: it is very effective, well tolerated, and has a prolonged efficacy.

Palliative pamidronate treatment in patients with bone metastases from breast cancer.

PURPOSE: An open, randomized study was performed to assess the effects of supportive pamidronate treatment on morbidity from bone metastases in breast cancer patients. PATIENTS AND METHODS: Eighty-one pamidronate patients and 80 control patients were monitored for a median of 18 and 21 months, respectively, for events of skeletal morbidity and the radiologic course of metastatic bone disease. The oral pamidronate dose was 600 mg/d (high dose [HD]) during the earliest study years, then changed to 300 mg/d (low dose [LD]) because of gastrointestinal toxicity. Twenty-nine of 81 pamidronate (HD/LD) patients first received 600 mg/d and were then changed to 300 mg/d; 52 of 81 pamidronate LD patients received 300 mg/d throughout the study. Tumor treatment was unrestricted. RESULTS: An overall intent-to-treat analysis was performed. In the pamidronate group, the occurrence of hypercalcemia, severe bone pain, and symptomatic impending fractures decreased by 65%, 30%, and 50%, respectively; event-rates of systemic treatment and radiotherapy decreased by 35% (P < or = .02). The event-free period (EFP), radiologic course of disease, and survival did not improve. Subgroup analyses suggested a dose-dependent treatment effect. Compared with their controls, in pamidronate HD/LD patients, events occurred 60% to 90% less frequently (P < or = .03) and the EFP was prolonged (P = .002). In pamidronate LD patients, event-rates decreased by 15% to 45% (P < or = .04). Gastrointestinal toxicity of pamidronate caused a 23% drop-out rate, but other cancer-associated factors seemed to contribute to this toxicity. CONCLUSION: Pamidronate treatment of breast cancer patients efficaciously reduced skeletal morbidity. The effect appeared to be dose-dependent. Further research on dose and mode of treatment is mandatory.

Application of an in vitro model and a clinical protocol in the assessment of the potency of a new bisphosphonate.

The development of new bisphosphonates for clinical use requires congruence between the results of basic and clinical investigations. We have previously shown that this can be achieved with the use of an in vitro coculture mouse metacarpal resorption system sensitive to the activation of osteoclast precursors together with a clinical protocol in which the rate of decrease in urinary hydroxyproline excess with bisphosphonate treatment is assessed in patients with Paget's disease. In these studies bisphosphonates of known potencies were used. In the present study we have evaluated these approaches prospectively in the assessment of the antiresorptive potency of the new bisphosphonate (3-dimethylamino-1-hydroxypropylidene)-1,1-bisphosphonate (dimethyl-APD). A total of 42 patients with Paget's disease of bone received dimethyl-APD in doses predicted from the in vitro system. A total of 24 patients received the bisphosphonate intravenously (2, 4, and 8 mg/day) in groups of 8 patients each and 18 orally (100, 200, and 400 mg/day) in groups of 6 patients each for 10 days. Dimethyl-APD therapy was highly effective in inhibiting bone resorption. Urinary hydroxyproline excretion reached 30.9 +/- 5.6, 17.1 +/- 3.1, and 2.1 +/- 5.3% of initial excess after 10 days treatment with intravenous dimethyl-APD, 2, 4, and 8 mg/day, and 37.4 +/- 18, 10.4 +/- 8.5, and 13 +/- 4.1% with oral therapy, 100, 200, and 400 mg/day, respectively. Comparison of the antiresorptive potency of dimethyl-APD with that of APD showed that the former is roughly five times more potent, as predicted in the in vitro study.(ABSTRACT TRUNCATED AT 250 WORDS)

Automated comparison of dual-photon absorptiometric studies of the lumbar spine.

An automated image comparison procedure was developed to optimize the precision of bone mineral density measurements by dual-photon absorptiometry. Changed acquisition conditions cause differences between two images to be compared. Alignment of one image with respect to the other is performed by a transformation that involves a rotation, a horizontal or vertical shift, and a correction for the soft tissue level. The best possible transformation is found in a stepwise search, guided by initial estimations of its parameters. After optimum transformation of one image, the region of interest of the other image is applied to both of them. Duplicate measurements of 9 patients and 15 normal subjects were performed; automated analysis yielded improved precision with respect to manual analysis. The coefficient of variation (CV) was also computed. The CV for automated analysis was 2.00% for patients and 1.04% for normal subjects compared to 3.55 and 1.93%, respectively, for manual analysis. For phantoms, the precision was 2.67% for manual analysis and 0.49% for automated analysis.

Improved treatment of Paget's disease with dimethylaminohydroxypropylidene bisphosphonate.

A group of 89 patients with Paget's disease of bone were treated with different intravenous or oral doses of the nitrogen-containing bisphosphonate dimethylaminohydroxypropylidene bisphosphonate (dimethyl-APD). Biochemical remission was obtained in 82% of treatments, and in the rest a clear response was found. Oral dimethyl-APD was well tolerated, and a dose of 200 mg/day for 10 days was sufficient to induce remission in the majority of patients. The remission probability was 3 months for 50% of patients, and the recurrence-free period was 27 months. The remission probability as well as the recurrence-free period did not differ among oral and intravenous treatments or among patients who had never been treated with nitrogen-containing bisphosphonates and those who had received pamidronate in the past and were treated for a recurrence of the disease. Dimethyl-APD is a very effective bisphosphonate devoid of side effects, which given for a short period can induce long-lasting remissions in patients with Paget's disease of bone.

Migration and phenotypic transformation of osteoclast precursors into mature osteoclasts: the effect of a bisphosphonate.

Osteoclast-devoid bone explants were cultured together with embryonic liver as a source of osteoclast precursors, but separated from each other by a filter. Cells migrated through the filter toward the calcified matrix and acquired the characteristics of mature, tartrate-resistant acid phosphatase-positive (TRAP+) osteoclasts upon contact with the bone explant. Migration and attachment could be visualized separately. Progressive reduction of filter pore size resulted in progressive reduction of resorption because the use of smaller pores made it increasingly difficult for cells to pass. Indeed, the use of 0.22-micron filters, through which no cells can pass, but which still allow full passage of medium, completely blocked the resorption. When migrating cells from fetal liver were arrested for 10 days by using a combination of filters with different pore sizes, the arrested cells showed a tendency to fuse just opposite the mineralized matrix. Furthermore, a great number of the arrested cells expressed the macrophage-specific cell-surface antigen F4/80 and showed acid phosphatase activity, but none of these cells were tartrate resistant. The acquisition of tartrate-resistant acid phosphatase activity upon contact with the bone explant and subsequent resorption of this explant could be prevented by exposure of the system to the bisphosphonate dimethyl-APD (Me2-APD), whereas migration of cells through the filter was not affected. We suggest that the bisphosphonate interferes with a matrix factor that is essential for the attachment and subsequent transformation of the osteoclast precursor into the mature phenotype.

Modulation of PTH-stimulated osteoclastic resorption by bisphosphonates in fetal mouse bone explants.

We examined the effects of the bisphosphonates Cl2MDP, APD, and Me2APD on osteoclastic resorption in the absence and presence of PTH using fetal mouse osteoclast-free bone explants cocultured with fetal liver as a source of osteoclast precursors. Results revealed qualitative and quantitative differences among the bisphosphonates tested. With Cl2MDP and APD fractional inhibition of resorption (measured as 45Ca release) in the presence of PTH was proportional to that obtained in its absence. In contrast, Me2APD, which is the most potent inhibitor of the three, was found at low concentrations (less than or equal to 5 x 10(-7) M) to enhance the PTH-stimulated osteoclastic resorption. APD as well, at concentrations that could not inhibit resorption, had a similar effect, but Cl2MDP did not. These studies describe a new phenomenon, that low doses of nitrogen-containing bisphosphonates can act synergistically with PTH and enhance osteoclastic resorption. These findings may have clinical implications in the management of patients with increased osteoclastic resorption due to parathyroid overactivity.

Characteristics and bisphosphonate treatment of a patient with juvenile osteoporosis.

We studied a 13 1/2-yr-old boy with severe juvenile osteoporosis and multiple metaphyseal and vertebral fractures. Biochemically, there was evidence of non-PTH mediated excessive bone resorption, low intestinal calcium absorption, and a strikingly negative calcium balance. He was treated with (3-amino-1-hydroxypropylidene)-1,1-bisphosphonate, a bisphosphonate capable of inhibiting bone resorption rapidly, and had dramatic clinical and biochemical improvement. All indices of resorption were normal within a week after initiation of therapy and his 1,25-dihydroxyvitamin D concentration, which was only 9.6 pg/ml before treatment, rose to 62.4 pg/ml. These changes were associated with an increase in calcium absorption and positive calcium balance. Radiological improvement with healing of metaphyseal and one diaphyseal fractures and signs of sclerosis near the growth plates of the affected metaphyses and at the end plates of the vertebrae also occurred. (3-Amino-1-hydroxypropylidene)-1,1-bisphosphonate, therefore, with its rapid suppression of resorption and the accompanying hormonal changes, is a very effective treatment for juvenile osteoporosis. The primary defect of this obscure syndrome seems to be uncontrolled activity of metaphyseal osteoclasts; disturbances of vitamin D metabolism and of intestinal calcium absorption are secondary events.

Serum osteocalcin in Paget's disease of bone: basal concentrations and response to bisphosphonate treatment.

Serum osteocalcin concentrations were measured in 42 patients with Paget's disease of bone and elevated serum alkaline phosphatase (AP) levels. High serum osteocalcin levels were found in only 22 patients. Serum osteocalcin was significantly correlated with urinary hydroxyproline excretion (r = 0.747; P less than 0.001) and, to a lesser extent, with serum AP levels (r = 0.483; P less than 0.01). In 23 patients who were followed during treatment with iv (3-amino-1-hydroxypropylidene) 1,1-bisphosphonate (APD) for 10 days, a dissociation among these 3 biochemical parameters was found. Urinary hydroxyproline excretion fell significantly (P less than 0.001), serum AP levels decreased, but not significantly, and serum osteocalcin concentrations increased progressively (P less than 0.001). This increase was greater when initial levels were lower than expected for the activity of the disease. The rise in serum osteocalcin correlated significantly with the concomitant increase in serum 1,25-dihydroxyvitamin D concentrations. Three months after initiation of treatment, all 3 parameters, urinary OHP excretion, serum AP, and serum osteocalcin levels, were near or within the normal range. These results indicate that serum osteocalcin is not a clinically useful parameter for assessment of the activity of Paget's disease. Its basal concentrations lag behind those expected from the activity of the disease, suggesting defective osteocalcin production. It appears that the functions of osteocalcin and AP as well as their initial expression by the osteoblasts are different and that this difference may be important for the quality of bone formed in Paget's disease. APD can modulate the release of osteocalcin, possibly through stimulation of 1,25-dihydroxyvitamin D production, although other factors may be involved.

The use of bisphosphonates in the treatment of osteoporosis.

The efficacy of bisphosphonates in the treatment of conditions characterized by increased osteoclastic bone resorption has been established. Recent evidence indicates that these compounds are also effective in the treatment of patients with osteoporosis. Two main protocols have been tried. One is based on the intermittent administration of the bisphosphonate, which is expected to decrease bone resorption, and give a drug-free period during which bone formation may proceed at a normal rate, leading to a positive calcium balance. The other argues that the resetting of the equilibrium in a cyclical process is, as a rule, incomplete and continuous low-grade suppression of resorption will result in a continuing positive bone balance. Intermittent administration of the first generation bisphosphonate, etidronate, for up to three years increases trabecular bone density, stabilizes it after two years, and appears to reduce the rate of new vertebral fractures in women with postmenopausal osteoporosis. Longer follow-up studies are needed before this beneficial effect is unequivocally established. Continuous administration of the second-generation bisphosphonate, pamidronate, increases spinal bone density in patients with osteoporosis linearly for up to four years, and is associated with a low rate of new vertebral fractures. These results need to be confirmed in controlled studies involving more patients. There are indications that pamidronate given continuously can prevent glucocorticoid-induced bone loss. There is no information about the effects of bisphosphonates on non-vertebral fractures. There are limited data about the use of bisphosphonates in the prevention of postmenopausal bone loss. Extensive studies on efficacy and safety are needed before this treatment is offered as an alternative to hormone replacement therapy.

The effect of supportive pamidronate treatment on aspects of quality of life of patients with advanced breast cancer.

Selective aspects of quality of life during supportive pamidronate (APD) treatment were assessed in breast cancer patients with osteolytic metastases. 144 patients were randomised to a pamidronate group (n = 76) or a control group (n = 68). A questionnaire measuring mobility impairment, bone pain, fatigue and gastrointestinal toxicity was administered at 3-monthly intervals. The analysis focused on changes in these quality of life domains over time. The median follow-up for both groups was 18 months. Mobility impairment and bone pain were significantly less in the pamidronate group as compared with the control group, due primarily to a rapid improvement shortly after initiation of pamidronate treatment. Thereafter, a gradual increase in these symptoms was noted in both groups. Gastrointestinal complaints and fatigue levels were similar over time in the two groups, suggesting that these symptoms are more dependent on disease-related events and cytotoxic treatment than on pamidronate treatment. The results indicate that reduced skeletal morbidity in breast cancer patients during pamidronate treatments is associated with an improvement in selective aspects of quality of life.

Role of bone and kidney in tumor-induced hypercalcemia and its treatment with bisphosphonate and sodium chloride.

The efficacy of intravenous aminohydroxypropylidene bisphosphonate as treatment for the hypercalcemia of malignancy was examined in a phase II multicenter study in 132 patients with a large variety of primary tumors. This provided an opportunity for an analysis of the separate influences of bone resorption and renal calcium handling on the genesis and maintenance of hypercalcemia. The results demonstrated that increased bone resorption is the major contributory factor and that inhibition with bisphosphonate normalizes the serum calcium concentration within five days in more than 90 percent of patients. Hypercalcemia is sustained by an inability of the kidney to deal efficiently with a chronically increased calcium load. This is influenced by the requirements of volume regulation in the presence of a sodium diuretic effect of hypercalcemia and is very sensitive to induced variations of sodium load. In addition, in a minority of patients, direct renal actions of tumor-derived humoral factors adversely reduce the ability to excrete calcium. For optimal treatment of tumor-induced hypercalcemia, bisphosphonate treatment should be combined with intravenous administration of saline solution.

Scintigraphic aspects of the recurrence of treated Paget's disease of bone.

The value of bone scintigraphy in the prediction and detection of a relapse of Paget's disease of bone after treatment, as well as the pattern of such a recurrence, were studied in a group of 40 patients. Thirty of these received a combination of calcitonin and HEDP, ten were treated alternately with calcitonin and HEDP. Scintigraphic deterioration is reliable evidence for a recurrence of Paget's disease of bone; one third of all recurrences was noted first on the bone scintigram. In another third of the cases of recurrence, however, the scintigram showed virtually no signs of deterioration. Scintigraphically a recurrence appears as a diffuse and homogeneous increase in activity in an affected part of the skeleton, or a focal and spotty increase of uptake in a diseased area, or a progression of a lesion beyond its original boundaries into healthy bone. Recurrence is usually not a generalized process occurring throughout the skeleton, but remains restricted to one or several lesions. Recurrence after combined treatment appeared to differ in nature from that seen after the use of calcitonin alone; the former was probably due to local exacerbation of the disease, probably caused by insufficient suppression of the Pagetic cells at these sites. The chance of recurrence could not be predicted on the basis of the pretreatment bone scintigram.

Limited precision of lumbar spine dual-photon absorptiometry by variations in the soft-tissue background.

The estimation error due to variations in soft-tissue baseline in lumbar bone mineral content (BMC) measured by dual-photon absorptiometry (DPA) was calculated with a new method of automatic baseline subtraction. In water phantom measurements, the s.d. of the soft-tissue (ST) baseline matched closely (r = 0.98) to the random error, calculated using 44 keV and 100 keV count rates and the directly determined baseline variations. In 21 volunteers and in 70 patients with osteoporosis, the ST variations were larger than the expected random error, revealing a source of error related to the inhomogeneity of soft tissue. The estimation error in BMC caused by ST variations was 0.7% in healthy subjects (mean BMC 40.5 gHA) and 1.5% in patients (mean BMC = 26.4 gHA). These results indicate that ST-related errors are an important limit to the precision of lumbar DPA measurements.

Primary oxalosis: clinical and biochemical response to high-dose pyridoxine therapy.

Although pyridoxine hydrochloride (vitamin B6) is known to reduce the endogenous production of oxalate in some individuals with primary oxalosis, the dose for a satisfactory trial of treatment is not established. We report two cases of primary oxalosis on a daily regimen of 1 g pyridoxine hydrochloride, in which 24-hr urinary oxalate excretion decreased by 60% and 70%, respectively, with corresponding clinical benefit. The responses have been sustained up to 2.5 yr in one case, and 20 mo in the other. In the patient with renal failure, serum creatinine decreased from 243 to 146 mumole/liter after 15 mo of treatment. The decrease in glycollic acid excretion in both patients was consistent with an increase of glyoxalate transaminase activity by the vitamin. Supranormal levels of erythrocyte glutamic oxaloacetate transaminase (egot) activity were observed during therapy, and these may be useful as a measure of the effective dose of pyridoxine.

Effect of long-term bisphosphonate treatment on morbidity due to bone metastases in breast cancer patients.

The effect of long-term bisphosphonate (APD) treatment on the morbidity from bone metastases in breast cancer patients was studied in a controlled clinical trial. 131 patients were randomized between treatment with APD (300 mg/day orally) or control. Systemic treatment for breast cancer was left to the discretion of the physician. The distribution of cases according to age, receptor status and previous treatment was similar in both groups. Patients were examined at 3-month intervals, while bone scans and radiography of relevant lesions in the skeleton were performed every 6 months. After a median follow-up of 13 months, the morbidity in the treated group was significantly less than in the controls. This concerned the occurrence of hypercalcemia, bone pain and fractures, and the need for radiotherapy of osteolytic lesions. In this interim analysis, APD treatment more than halved the requirement for specific treatment of bone lesions. The treatment is simple and well tolerated at a relatively low dosage. A higher oral dose was precluded due to gastrointestinal toxicity. Because the effect of APD on skeletal morbidity was not complete, efforts should be made to develop more effective and less toxic bisphosphonates.

Magnetic resonance imaging in Paget disease of the skull.

Four cases of Paget disease of the skull were studied with magnetic resonance (MR) imaging. With optimal use of projection and technical factors, MR permits simultaneous demonstration of osseous deformity and its relation to the underlying soft tissues. Effects on the brain caused by thickened calvaria and brainstem compression from basilar impression can be detected readily on a single sagittal scan.

A simple slide-rule method for the assessment of renal tubular reaborption of phosphate in man.

The activity of renal tubular reabsorption of phosphate in man is best expressed as the ratio of the maximum rate or reabsorption to the glomerular filtration rate (TmP/GFR). A slide-rule method based on existing data is described for the derivation of TmP/GFR from values of phosphate and creatinine concentrations in single samples of plasma and urine. This is a simple method which is suitable both for research and for clinical purposes.