S12911-2 reduces bone loss induced by short-term immobilization in rats.

Skeletal immobilization induces trabecular bone loss resulting from increased bone resorption and decreased formation. In this study we determined the effect of S12911-2, a compound containing two atoms of stable strontium, on trabecular bone loss induced by short-term immobilization of hind limbs in rats. Male Sprague-Dawley rats were randomly allocated to six groups (n = 25 per group). At 9 weeks of age, five groups of rats had their right hind limb immobilized for 10 days, using a plaster cast, whereas one control group was not immobilized (CT). Four groups of immobilized rats were treated for 10 days with 50, 200, or 800 mg/kg/day of S12911-2 or the vehicle. One group of immobilized rats was pretreated (PT) for 2 weeks with 200 mg/kg/day of S12911-2 and continued treatment during the immobilization period. Immobilization of the right hind limb induced bone loss as shown by decreased ash weight (-12%) and bone mineral density measured by dual energy x-ray absorptiometry of the femur (-9%), and confirmed by decreased trabecular bone volume measured by histomorphometry of the tibial metaphysis (-25%). This effect was unrelated to alteration in long bone length and was associated with increased urinary hydroxyproline excretion (+12%), increased osteoclast surface and number (+27%), decreased mineral apposition rate (-30%), and tetracycline double labeled surface (-17%) in the immobilized tibia. S12911-2 (800 mg/kg/day) partially reduced bone loss, as shown by increased bone mineral density (+4%) and trabecular bone volume (+19%) compared with untreated immobilized rats. Furthermore, S12911-2 (800 mg/kg/day) increased bone density (+5%) in the contralateral nonimmobilized leg. These effects resulted from inhibition of bone resorption, as shown by normalization of urinary hydroxyproline excretion and histomorphometric indices of bone resorption. This study shows that the bone resorption induced by immobilization in rats can be suppressed by treatment with S12911-2, resulting in partial reduction of the bone loss.

Influence of alveolar ventilation changes on calculated gastric intramucosal pH and gastric-arterial PCO2 difference.

OBJECTIVE: To evaluate the influence of changes in alveolar ventilation on the following tonometry-derived variables: gastric intramucosal CO2 tension (PtCO2), gastric arterial CO2 tension difference (PgapCO2), gastric intramucosal pH (pHi) and arterial pH-pHi difference (pHgap). DESIGN: Clinical prospective study. SETTING: A medical intensive care unit in a university hospital. PATIENTS: Ten critically ill, mechanically ventilated patients requiring hemodynamic monitoring with pulmonary artery catheter. INTERVENTIONS: Gastric tonometer placement. A progressive increase in tidal volume (V(T)) from 7 to 10 ml/ kg followed by an abrupt return to baseline V(T) level. MEASUREMENTS AND MAIN RESULTS: Tonometer saline PtCO2 and hemodynamic data were collected hourly at various V(T) levels: H0 and H0' (baseline V(T) = 7 ml/kg), H1 (V(T) = 8 ml/kg), H2 (V(T) = 9 ml/kg), H3 (V(T) = 10 ml/kg), H4 (baseline V(T)). During the "hyperventilation phase" (H0-H3), pHi (p<0.01) and pHgap (p<0.05) increased but PgapCO2 remained unchanged. Cardiac output (CO) was not affected by ventilatory change. During the "hypoventilation phase" (H3-H4), pHi fell from 7.27+/-0.11 to 7.23+/-0.09 (p<0.01) and PgapCO2 decreased from 16+/-5 mm Hg to 13+/-4 mm Hg (p<0.05). V(T) reduction was associated with a significant cardiac output elevation (p<0.05). CONCLUSIONS: PaCO2 and PtCO2 are similarly influenced by the changes in alveolar ventilation. Unlike pHi, the PgapCO2 is not affected by ventilation variations unless CO changes are associated.

Pulsed estrogen therapy: pharmacokinetics of intranasal 17-beta-estradiol (S21400) in postmenopausal women and comparison with oral and transdermal formulations.

Pharmacokinetics of estradiol and estrone were assessed in postmenopausal women receiving S21400, a novel 17beta-estradiol formulation administered by nasal route; the results were compared with those obtained with oral and transdermal routes. Thirty six women received three treatments: a specified dose of 17beta-estradiol (100, 300 or 450 microg) given once and as 2 doses, 12 h apart, using three parallel dose groups in a randomised, crossover study. Thereafter, a reservoir patch (50 microg/day of 17beta-estradiol) or a tablet of 2 mg micronised 17beta-estradiol were randomly administered. Plasma concentrations of estradiol and estrone were measured by radioimmunoassays. Following intranasal dosing, estradiol was rapidly absorbed with plasma concentrations reaching maximal values (approximately 1400 pg/ml with a single 300 microg dose) after 10-30 min and returning within 12 h to levels of untreated postmenopausal women. Systemic exposure to estradiol was dose proportional and independent of the treatment regimen. Moreover, the dose of 300 microg gave an estimated 24 h systemic exposure to exogenous estradiol close to that of the 50 microg/day reservoir patch or the 2 mg tablet. The mean estrone to estradiol ratio was similar and 4-fold lower than those with the patch and the tablet, respectively. In conclusion, by this new route for estrogen replacement therapy, the nasal route, the pharmacokinetics of estradiol as S21400 were linear and displayed a 'pulsed' kinetic profile, different from those obtained with the usual routes of administration.

Strontium distribution and interactions with bone mineral in monkey iliac bone after strontium salt (S 12911) administration.

The analysis of the interaction of strontium (Sr) with bone mineral is of interest because a new agent containing Sr (S 12911) has shown positive effects on bone mass in various animal models of osteoporosis and is currently being developed for preventive and curative treatment of postmenopausal osteoporosis. Iliac bone samples were obtained from 20 male monkeys: 4 untreated control animals, 12 animals sacrificed at the end of a 13-week treatment with high dose levels of S 12911 (750, 275, or 100 mg/kg/day orally), and 4 animals sacrificed 6 weeks after the end of a 13-week treatment with S 12911 (750 or 100 mg/kg/day orally). The distribution of Sr was determined and quantified by X-ray microanalysis. Changes at the crystal level were evaluated by X-ray diffraction and Raman microspectrometry. In the control animals, traces of Sr were found to be homogeneously distributed throughout the bone tissue. In the treated monkeys, Sr could only be detected in calcified matrix. In monkeys sacrificed at the end of the treatment, Sr was found to be dose-dependently incorporated into the mineral substance of the compact and cancellous bone. Sr was heterogeneously distributed with three to four times more Sr in new than in old compact bone, and approximately two and a half times more Sr in new than in old cancellous bone. The bone Sr content dramatically decreased in the animals sacrificed 6 weeks after the end of the treatment. Diffraction showed no significant changes in the characteristics of the crystal lattice. Sr appeared to be easily exchangeable from bone mineral and was slightly linked to mature crystals through ionic substitutions. Even at the highest dose level tested, less than 1 calcium ion out of 10 was substituted by 1 Sr ion in each crystal. In conclusion, taken up by bone, Sr was heterogeneously distributed with a higher concentration in new than in old bone but induced no major modifications of the bone mineral (crystallinity, crystal structure) at the crystal level. As a result, a treatment with S 12911 Sr salt should not induce any alteration of bone mineral.

The divalent strontium salt S12911 enhances bone cell replication and bone formation in vitro.

In this study, we have determined the effect of the divalent strontium salt S12911 on bone cell replication and bone formation in two culture systems. In the first series of experiments, half-calvariae of newborn rats were cultured with S12911 from 24 to 96 h and labeled with 3H-thymidine for the last 6 h of culture or treated with S12911 for 24 h and labeled for 24 h with 3H-proline 24-48 h after the removal of the agent. Calvariae were then processed for histomorphometry. S12911 at 10(-3) M increased the replication of preosteoblastic cells by 30-50% after 24 h and by 60% after 96 h of treatment. This effect was specific, since the number of labeled osteoblasts and of periosteal cells was not changed. A transient 24 h treatment with S12911 at 10(-3) M increased bone formation 24 and 48 h after the removal of the agent. 3H-proline labeled surfaces and bone formation rates were increased by 20%-35%. In the second series of experiments, sequential collagenase digestions were used to isolate cell populations enriched in fibroblasts or osteoblasts (Ob) from 22 day fetal rat calvariae. Treatment with S12911 at 10(-3) M for 24 h enhanced DNA synthesis by three- to fourfold in cell populations enriched in fibroblasts and preosteoblastic cells. The effect was less pronounced and inconsistent in Ob cells. S12911 at 10(-3) M for 24 h also increased collagen and non-collagen protein synthesis by 35% in Ob cells. These data indicate that the divalent strontium salt S12911 enhances bone cell replication and bone formation in vitro, an effect that may contribute to the previously reported effects of S12911 on trabecular bone mass in vivo.

Strontium increases vertebral bone volume in rats at a low dose that does not induce detectable mineralization defect.

Low doses of strontium and fluoride were shown to increase bone formation and trabecular bone density in rodents. To assess whether strontium or fluoride affect the quality of the mineral at doses known to increase bone density, we have determined the effects of low doses of strontium and fluoride on bone formation and bone mineral characteristics in rats. Adult rats were given strontium alone (0.20%), fluoride alone (1 mg/kg per day), or the combined treatment for 8 weeks. Strontium levels in serum and femur were similar in groups treated with strontium alone or in combination, being about 5% of calcium levels. Biochemical and neutron activation analyses in femur showed that calcium and magnesium contents did not differ in the four group of rats, suggesting that strontium was incorporated in the apatite lattice of the bone minerals in the strontium-treated rats. The mineralized bone volume was significantly increased by 17% in the strontium-treated group, by 20% in the fluoride-treated group, and by 19% in rats given with the combined treatment. This was associated with increased osteoid surface, osteoblast surface, and double tetracycline labeled surfaces in the strontium-treated and fluoride-treated groups, showing that the number of bone forming sites was increased. However, the mineral apposition rate, the osteoid thickness, and the mineralization lag time were similar in controls and treated groups, reflecting the lack of deleterious effects of low doses of strontium and fluoride on bone mineralization. The density fractionation analysis measured in the femur also showed that neither strontium, nor fluoride at the low doses used, significantly altered the mineralization profile. The results indicate that treatment with low doses of strontium or fluoride increase the number of bone forming sites and vertebral bone volume in rats, but does not have detectable adverse effects on the mineral profile, bone mineral chemistry or bone matrix mineralization.

Blood pressure and arterial lactate level are early indicators of short-term survival in human septic shock.

OBJECTIVE: To identify early prognostic markers of septic shock among catheterization-derived hemodynamic and metabolic data. DESIGN: Prospective cohort study. SETTING: A medical intensive care unit in a university hospital. PATIENTS: Thirty-two consecutive patients with septic shock, separated into two groups according to short-term (10-day) evolution: 18 acute survivors and 14 fatalities. MEASUREMENTS: Usual hemodynamic and metabolic variables were measured at the onset of shock, i.e., when the catheter was inserted (T0), and 24 h later (T24). The values collected for each group at T0 and T24 and their 24-h changes were compared. RESULTS: On admission, no difference was found between acute survivors and eventual fatalities. After 24 h, fatalities presented with significantly lower mean arterial pressure (p <0.01), left ventricular stroke work index (p <0.05) and higher lactate levels (p <0.01) than acute survivors. Moreover, the 24-h changes of lactate and blood pressure were also of prognostic value (p <0.05). Oxygen delivery and oxygen consumption did not differ statistically between the two groups. At T24, a mean arterial pressure of less than 85 mmHg and a lactate level equal to or greater than 3.5 mmol/l were independently associated with poor survival (37.5% and 30.7%, respectively). Day 10 survival was only 12.5% when both criteria were present at T24. CONCLUSIONS: Changes in mean arterial pressure and arterial blood lactate within the first 24 h of treatment are strong prognostic indicators of short-term survival in patients with septic shock. After 24 h of treatment, maintenance of a mean blood pressure equal to or greater than 85 mmHg correlates with survival at day 10. Data suggest that early reductions in both cardiac function and vascular tone play a determining role in the hypotension observed in fatalities. Persistence of hyperlactatemia in hypotensive patients bodes particularly ill. Blood pressure and lactate level are simple bedside parameters that can enable the clinician to identify patients with a high risk of mortality.

Comparison between bone density and bone strength in glucocorticoid-treated aged ewes.

In order to assess if bone densitometry could be used as an indicator to evaluate bone fragility in short term studies performed on glucocorticoid-treated ewes, correlations between DXA measurements and biomechanical parameters obtained on the same bones were established in 27 aged ewes including sixteen animals treated with methylprednisolone 15 mg/day for 4 months and eleven untreated animals. DXA measurements were performed ex-vivo on HOLOGIC QDR-1000+ device. Biomechanical testings included a three-point bending test on the femur and a compression test on cylinders of cancellous bone excised from two lumbar vertebrae selected between L6 and L4. At the femoral site, bone mineral density was correlated with the bending stiffness (r = 0.65) and the ultimate bending strength (r = 0.64) whereas, at the vertebral site, biomechanical parameters failed to correlate with bone mineral density assessed by DXA. This apparent lack of correlation between vertebral bone mass and trabecular bone strength is mainly linked to anatomical characteristics of the ewe: in this species, the vertebral posterior arches, which consist mainly of cortical bone, are very large compared to the vertebral body and strongly influence the bone mineral density evaluated on the intact vertebra. This is not the case with other large animals, for instance non-human primates. In conclusion, DXA can give a good evaluation of bone strength for ewe femurs, but results must be interpreted carefully at the vertebral site due to the anatomical characteristics of this animal species.

[Prognosis of acute tuberculous respiratory distress syndrome. 4 cases]. / Pronostic du syndrome de détresse respiratoire aiguë tuberculeux. 4 observations.

OBJECTIVES: We examined the characteristics of 4 cases of adult respiratory distress syndrome in patients with tuberculosis in an attempt to improve prognosis. METHODS: Four new cases of adult respiratory distress syndrome were described together with a review of the cases reported in the literature. Inclusion criteria were the presence of the syndrome as defined according to the American-European consensus conference and the criteria described by Murray et al. and identification of the mycobacteria causing tuberculosis. RESULTS: A total of 52 cases were included in the study. The sex ratio was 0.71 and mean age 46 +/- 15 years. Eight patients had a past history of pulmonary tuberculosis. Alcoholism was the primary immunodepression factor observed (35%) followed by human immunodeficiency virus infection (13%). For 74% of the patients, the disease course lasted 7 days. The initial chest X-ray was suggestive of tuberculosis in 11. Intradermoreaction to tuberculin was positive in 2 out of 17 patients. Direct examination of non-invasive respiratory samples was positive in 44% for mycobacteria. Disseminated tuberculosis was seen in 64%. Anti-tuberculosis antibiotherapy was started on the first day of intensive care in 68% of the patients; rapid treatment was associated with better prognosis: 1.5 +/- 1.2 days versus 3 +/- 2.7 in fatal cases (p = 0.02). Adjuvant corticosteroid therapy was used in 46% of the cases and was apparently associated with unfavourable outcome: 74% mortality versus 58% without corticosteroids. Ventilatory assistance was required in 88% and associated with poor prognosis (13% survival versus 100% without assistance) (p < 10(-3)). Outcome was fatal in 36 cases (70%) with a mean delay of 9.7 +/- 10.8 days. CONCLUSION: The conditions required for improving the prognosis of adult respiratory distress syndrome in tuberculosis patients included suspecting tuberculosis in all cases of acute respiratory failure of unknown origin, particularly in the immunodepressed patient, and to avoid missing this diagnosis in case of a non-suggestive chest X-ray and a negative though exhaustive microbiology search. Adjuvant corticotherapy is uneffective and may be dangerous.

An uncoupling agent containing strontium prevents bone loss by depressing bone resorption and maintaining bone formation in estrogen-deficient rats.

Trabecular bone loss in estrogen deficiency is associated with enhanced bone resorption with a smaller increase in bone formation. We previously reported that low doses of strontium can increase trabecular bone volume in rodents by affecting bone resorption and formation. In this study we determined the effect of a new divalent strontium salt (S12911) on bone loss induced by E2 deficiency. Sprague-Dawley female rats (230 g, n = 15-25 per group) were sham operated or ovariectomized (OVX) and treated with 17 beta-estradiol (E2, 10 micrograms/kg/day, sc) or S12911 by gavage at the dose of 77, 154, or 308 mg/kg/day or the vehicle. Treatment for 60 days with S12911 resulted in a dose-dependent increase in plasma, urine, and bone strontium concentrations without any deleterious effect on total or skeletal growth. OVX rats were osteopenic compared to sham rats as shown by decreased femoral dry bone weight and mineral content measured on bone ash and by DXA. Treatment of OVX rats with S12911 prevented bone loss as bone ash and bone mineral content were restored to the values in sham rats. Trabecular bone volume measured by histomorphometry on the tibial metaphysis was decreased by 46% in OVX rats and was corrected by E2. Treatment of OVX rats with S12911 increased the trabecular bone volume by 30-36%. Histomorphometric indices of bone resorption (osteoclast surface and number) were increased in OVX rats and were reduced by S12911 to the levels in sham rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetic profile of fotemustine in rat plasma by electrochemical detection.

1. A differential pulse polarographic (DDP) assay of diethyl-1-[3-(2-chloroethyl)-3-nitrosoureido] ethylphosphonate (fotemustine) was developed to determine the kinetics of this nitrosourea in plasma, brain, liver, lung and kidney. The optimized polarographic determination, previously applied to BCNU and CCNU, attained a limit of detection of 0.3 micrograms fotemustine/ml plasma and 1 microgram/g in other tissues; the calibration curve in electrolyte or in plasma was linear between 0.5 and 100 micrograms/ml. 2. The choice of electrolyte, the effects of pH, temperature, light, and the stability of fotemustine in samples were investigated. Recovery of fotemustine was 76-90% from lung greater than kidney greater than plasma greater than brain greater than liver; the variability coefficients were low (4.0-7.3%). Tissue samples could be stored for 20 days at -20 degrees C without loss of the compound. 3. Plasma kinetics of fotemustine and BCNU given to male rats at therapeutic doses (20 mg/kg i.v.) fitted a bi-exponential equation. Two minutes after injection plasma, levels of unchanged nitrosoureas were 15 and 11 micrograms/ml respectively. Fotemustine could be measured (0.92 microgram/ml) for 3 h, while BCNU could not be detected after 60 min. Unchanged fotemustine was cleared from the blood stream 3-5 times more slowly than BCNU.

In vitro chemosensitivity testing of Fotemustine (S 10036), a new antitumor nitrosourea.

Fotemustine (S 10036) is a new anti-tumor nitrosourea characterized by a phosphonoalanine carrier group coupled to the nitrosourea moiety, which potentially increases the cellular penetration of the drug. Using human tumor cell lines, the activity of S 10036 was compared with that of the more established nitrosoureas BCNU and CCNU. Growth-inhibiting effects were evaluated by the [3H]-thymidine incorporation test. In a panel of 12 human cancer cell lines [melanoma (4), ovary (2), head and neck (3), lung (1), bladder (1), breast (1)], the dose-response curves of S 10036 (0-100 microM) were similar to those obtained with equimolar concentrations of BCNU and CCNU; they indicated a moderately more marked effect for two and an equal effect for six melanoma cell lines with S 10036 as compared with BCNU. Moderate but significant synergistic combinations were obtained when S 10036 (0-80 microM) and CDDP (0-100 microM) or DTIC (250-6,500 microM) were combined in melanoma cell lines. In conclusion, the new nitrosourea S 10036 shows promising activity, particularly against human melanoma cell lines.

Cytotoxicity and DNA damaging effects of a new nitrosourea, fotemustine, diethyl- 1-(3-(2-chloroethyl)-3-nitrosoureido) ethylphosphonate-S10036.

Fotemustine is a new chloroethylnitrosourea which has recently entered a Phase II clinical trial. Using standard cytotoxicity analyses, Fotemustine was shown to be preferentially active in two Mer- cell lines, human colon BE and human lung A427. Comparative cell kill in the Mer+ counterparts HT29 and A549 (respectively) was significantly lower. In a mouse cell line, P388, alkaline elution studies showed that Fotemustine caused fewer DNA strand breaks and total crosslinks (including DNA-protein) than either BCNU or MeCCNU at equivalent cytotoxic concentrations. In addition, the removal of DNA damage caused by Fotemustine was more rapid than of damage, three times as much Fotemustine was required. These data suggest that the cytotoxic mechanism of Fotemustine, although subject to the same repair mechanisms as other nitrosoureas, may not be entirely dependent upon DNA as the sole drug target. The previously reported reduced mutagenicity of this agent may also be a function of the less extensive nucleic acid damage. The encouraging early clinical trial results with this drug may reflect its improved pharmacokinetics and bioavailability, rather than any significant modification in its cellular pharmacology when compared to other nitrosoureas.

[Study of the clinical pharmacokinetics of fotemustine in various tumor indications]. / Etude de pharmacocinétique clinique de la fotemustine dans différentes indications tumorales.

Fotemustine (S 10036) is a new nitrosourea compound whose antitumoral activity has been demonstrated, particularly in disseminated malignant melanoma. Pharmacokinetic parameters of this drug were investigated during phase II clinical trials and compared according to tumor type. Twenty-six patients entered the study and received an induction treatment (weekly 100 mg/sq.m of fotemustine in 250 ml of 5% glucose in water over a one-hour IV infusion for 3 consecutive weeks) followed by a 4-week rest period. A maintenance therapy (100 mg/sq.m every three weeks) was proposed in stabilized or responsive patients. Plasmatic assay of fotemustine was carried out by HPLC. Seventy-one cycles were analyzed. A short half-life and a large intra and inter-individual variability of all kinetic parameters (especially plasmatic clearance) was found independent of tumour type. The study of patient's clinical behaviour was shown to be related to the clearance value obtained during the first treatment cycle which seems to predict the clinical response in the case of malignant melanoma. This finding needs to be confirmed in a larger number of patients and in other tumor localizations.

[Clinical pharmacokinetics of nitrosoureas]. / Pharmacocinétique clinique des nitrosourées.

The pharmacokinetic characteristics of chloroethylnitrosourea anti-cancer agents are based on their high chemical reactivity and subsequent rapid breakdown in the plasma; and on a widespread tissue distribution due to the molecules' lipophilic properties. These physico-chemical properties explain the main problems that one may face during pharmacokinetic studies (assay method, isolation of high reactive intermediates) and that are related to the typical pharmacokinetic profile of these agents: rapid gastro-intestinal absorption, short half-life, widespread pulmonary and renal distribution, passage through the blood-brain barrier with levels within a therapeutic range, lipoprotein fixation, mainly hepatic and pulmonary metabolism, renal excretion. A drug interaction with phenobarbital has been described in the rat. The rational use of these compounds in cancer chemotherapy requires the optimisation of assay methods and a better understanding of their transformation pathways as well as their mechanism of action.