Clinical development of neridronate: potential for new applications

Neridronate is an aminobisphosphonate, licensed in Italy for the treatment of osteogenesis imperfecta (OI) and Paget's disease of bone (PDB). A characteristic property of neridronate is that it can be administered both intravenously and intramuscularly, providing a useful system for administration in homecare. In this review, we discuss the latest clinical results of neridronate administration in OI and PDB, as well as in osteoporosis and other conditions. We will focus in particular on the latest evidence of the effect of neridronate on treatment of complex regional pain syndrome type I.

Sclerostin and DKK1 in primary hyperparathyroidism

Bone formation is influenced by the Wnt pathway through effects on osteoblast functionality, and these actions are opposed by two antagonists: sclerostin and Dickkopf-1 (DKK1). Decreased levels of serum sclerostin were found after treatment with the PTH analogue teriparatide and in patients with primary hyperparathyroidism (PHPT), while treatment with teriparatide of postmenopausal osteoporosis is associated with increases in serum DKK1. We studied mineral metabolism and Wnt pathway in 21 postmenopausal women affected by PHPT and in 42 age-matched healthy women. Mean serum calcium and PTH were significantly higher and serum phosphates significantly lower in the PHPT group compared with the control group. Serum 25-OH-vitamin D (25OHD) was lower in PHPT patients and 1,25 dihydroxy-vitamin D [1,25(OH)2D] was significantly higher. Patients with PHPT had significantly higher levels of bone alkaline phosphatase (BAP) and of serum C-terminal telopeptides of type I collagene (sCTX). Serum sclerostin in PHPT was significantly lower (-26 %) and serum DKK1 significantly higher (+57 %) than in healthy control subjects. Serum PTH was positively correlated with 1,25OH2D (p < 0.001), BAP (p = 0.036), sCTX (p = 0.003), and DKK1 (p = 0.007) and negatively with 25OHD (p = 0.002) and sclerostin (p = 0.02). In PHPT patients, serum sclerostin was negatively correlated with BAP (p = 0.038) and sCTX (p = 0.07). Patients with PHPT have significantly lower sclerostin and higher DKK1 levels compared with healthy postmenopausal control subjects. Further studies are warranted in order to verify whether the balance between these two opposite effects on Wnt function might help explain the variable bone involvement among patients with PHPT.

Milliwatt-level frequency combs in the 8-14 μm range via difference frequency generation from an Er:fiber oscillator

We report on the generation of mid-infrared (mid-IR) pulses with a maximum average optical power of 4 mW and wide tunability in the 8-14 μm range via difference frequency generation (DFG) in GaSe from an Er:fiber laser oscillator. The DFG process is seeded with self-frequency shifted Raman solitons that are shown to be phase coherent within the whole tuning range, from 1.76 to 1.93 μm. Interference measurements between adjacent pulses at the idler wavelengths attest coherence transfer to the mid-IR.

Duration of treatment for osteoporosis

Many treatments for postmenopausal osteoporosis with proven efficacy in lowering fracture risk had become available since many years now. In the last few years the issue about treatment duration has become a matter of importance. In this paper the pivotal trials for alendronate, risedronate, zoledronate and other anti reabsorptive drugs such as denosumab are revised with particular attention to the extension studies aimed to verify the effect of drug discontinuation. The results of the review highlight differences among the available drugs and the practical clinical consequences also in terms of cost-effectiveness.

Long-term effects of amino-bisphosphonates on circulating γδ T cells

The aim of this study was to explore whether desensitization to the occurrence of the acute-phase response (APR) in patients previously treated with amino-bisphosphonates (N-BPs) is due to a long-lasting reduction in the number of circulating γδ T cells. Circulating lymphocyte subpopulation counts were obtained from 63 patients with postmenopausal or senile osteoporosis at baseline and after 2 days and 12 months of the first intravenous (IV) 5 mg zoledronic acid (ZOL) infusion. At baseline both the proportion and absolute number of circulating γδ T cells were significantly higher in patients who had never used N-BPs vs. previous users, either oral or IV. A typical APR was observed in none of the patients given IV ZOL a year earlier, in 6 (22 %) of the patients previously treated with oral N-BPs, and in 13 (57 %) of the patients naive to any N-BP treatment. In patients naive to N-BPs, a significant reduction in both total lymphocytes and their subsets was observed 2 days after ZOL infusion; all these changes returned to baseline values 1 year later with the exception of γδ T cells, which remained significantly lower in terms of both proportion and absolute number. These results indicate for the first time that both IV and oral N-BP treatments are associated with a long-lasting decrease in circulating γδ T cells, and this may explain the lower incidence of APR in patients previously exposed to N-BPs. Other clinical implications of this sustained effect of N-BPs on immune-regulatory cells might be important.

Dose-dependent short-term effects of single high doses of oral vitamin D(3) on bone turnover markers

We investigated the short-term effects on bone turnover markers of high doses of vitamin D(3) in order to identify what initial therapeutic dose can be safely administered in vitamin D-deficient subjects. Thirty-seven elderly subjects [mean age 75 ± 3 (SD) years] were consecutively randomized to the administration of a single oral bolus of 600000, 300000, or 100000 IU vitamin D(3). Blood samples were taken at baseline and 1, 3, 7, 14, 30, 60, and 90 days after vitamin D(3) administration. Twenty-four subjects served as controls. No relevant changes in bone turnover markers [C-terminal telopeptides of type I collagen (sCTX) and bone-specific alkaline phosphatase (BAP)] were observed in the controls. In treated patients a dose-dependent effect on sCTX was observed. With the administration of 600,000 IU vitamin D(3) a significant increase of sCTX was observed already at day 1, and it was sustained for 2 months. The changes in sCTX with smaller doses were considerably lower and reached statistical significance only within the first 3 days with the 300,000 IU dose. BAP remained unchanged in patients given 300,000 and 600,000 IU vitamin D(3), while it significantly rose by 15-23 % throughout the observation period in patients given 100,000 IU. Our results indicate that the use of a vitamin D bolus exceeding 100,000 IU may be associated with acute increases of sCTX.

Treatment of complex regional pain syndrome type I with neridronate: a randomized, double-blind, placebo-controlled study

OBJECTIVE

Complex regional pain syndrome type I (CRPS-I) is a severely disabling pain syndrome for which no definite treatment has been established. The aim of this multi-centre, randomized, double-blind placebo-controlled trial was to test the efficacy of the amino-bisphosphonate neridronate in patients with CRP-I.

METHODS

Eighty-two patients with CRP-I at either hand or foot were randomly assigned to i.v. infusion of 100 mg neridronate given four times over 10 days or placebo. After 50 days the former placebo patients were given open label the same regimen of neridronate.

RESULTS

Within the first 20 days, visual analogue scale (VAS) score decreased significantly more in the neridronate group. In the following 20 days, VAS remained unchanged in the placebo group and further decreased in the active group by 46.5 mm (95% CI -52.5, -40.5) vs 22.6 mm (95% CI -28.8, -16.3) for placebo group (P < 0.0001). Significant improvements vs placebo were observed also for a number of other indices of pain and quality of life. During the open-extension phase in the formerly placebo group the results of treatment were superimposable on those seen during the blind phase in the active group. A year later none of the patients was referring symptoms linked to CRPS-I.

CONCLUSION

In patients with acute CRPS-I, four i.v. infusions of neridronate 100 mg are associated with clinically relevant and persistent benefits. These results provide conclusive evidence that the use of bisphosphonates, at appropriate doses, is the treatment of choice for CRPS-I.

TRIAL REGISTRATION

EU Clinical Trials Register, https://www.clinicaltrialsregister.eu/, 2007-003372-18.

Sclerostin and DKK1 in postmenopausal osteoporosis treated with denosumab

The bone mass benefits of antiresorbers in postmenopausal osteoporosis are limited by the rapid coupling of decreasing bone resorption with bone formation. Wnt signaling is involved in this coupling process during treatment with bisphosphonates, whereas its role during treatment with the anti-receptor activator of NF-κB ligand (RANKL) antibody denosumab is unknown. The study population includes patients participating in a placebo-controlled trial lasting 36 months: 19 women were on placebo and 24 on subcutaneous 60 mg denosumab every 6 months. All measured parameters (serum C-terminal telopeptide of type I collagen [sCTX], serum bone alkaline phosphatase [bAP], Dickkopf-1 [DKK1], and sclerostin) remained unchanged during the observation period in the placebo group. sCTX and bAP were significantly suppressed by denosumab treatment over the entire follow-up. Denosumab treatment was associated with significant (p < 0.05) increases (28% to 32%) in serum sclerostin over the entire study follow-up. Serum DKK1 significantly decreased within the first 6 months with a trend for further continuous decreases, which reached statistical significance (p < 0.05) versus placebo group from the 18th month onward. The changes in DKK1 were significantly and positively related with the changes in sCTX and bAP and negatively with hip bone mineral density (BMD) changes. The changes in sclerostin were significantly and negatively related only with those of bAP. The changes in bone turnover markers associated with denosumab treatment of postmenopausal osteoporosis is associated with significant increase in sclerostin similar to those seen after long-term treatment with bisphosphonates and significant decrease in DKK1. This latter observation might explain the continuous increase over 5 years in BMD observed during treatment of postmenopausal osteoporosis with denosumab.

Frequency-stabilized 1 W optical comb at 2.2-2.6 μm by Cr2+:ZnSe multipass amplification

We present a frequency comb source with power level up to 150 μW per comb mode, tunable in the 2.2-2.6 μm wavelength region, based on a Cr(2+):ZnSe multipass solid-state amplifier seeded by the output of an actively stabilized optical parametric oscillator, synchronously pumped by a commercial 250 MHz Er:fiber laser. Phase relationship between idler, signal, and pump waves is exploited to perform frequency comb stabilization in the whole 2.2-2.6 μm mid-infrared spectral region.

Coherent phase lock of a 9 μm quantum cascade laser to a 2 μm thulium optical frequency comb

We demonstrate coherent phase locking of a room-temperature continuous-wave quantum cascade laser (QCL) at 9.1 μm to a Tm-fiber laser frequency comb centered at 2 μm, with an integrated residual phase error of 0.9 rad (30 mHz to 1.5 MHz). This resulted in a QCL linewidth reduction from 525 to 25 kHz at 1 ms observation time, limited by the linewidth of the free-running frequency comb.

250-MHz synchronously pumped optical parametric oscillator at 2.25-2.6 μm and 4.1-4.9 μm

A compact and versatile femtosecond mid-IR source is presented, based on an optical parametric oscillator (OPO) synchronously pumped by a commercial 250-MHz Er:fiber laser. The mid-IR spectrum can be tuned in the range 2.25-2.6 μm (signal) and 4.1-4.9 μm (idler), with average power from 20 to 60 mW. At 2.5 μm a minimum pulse duration of 110 fs and a power of 40 mW have been obtained. Active stabilization of the OPO cavity length has been achieved in the whole tuning range.

Wide-bandwidth phase lock between a CW laser and a frequency comb based on a feed-forward configuration

Wide-bandwidth phase lock between the tooth of a frequency comb and a CW extended-cavity diode laser at 1.55 μm is achieved by the use of an acousto-optical frequency shifter in a feed-forward configuration. The coherence properties of the comb are efficiently transferred to the CW laser, whose linewidth is narrowed down to the ∼10 KHz comb level. A maximum control bandwidth of ∼0.6 MHz has been experimentally achieved, limited by the transit time of the acoustic wave inside the frequency shifter.

Short-term effects on bone turnover markers of a single high dose of oral vitamin D₃

CONTEXT

Vitamin D deficiency is often treated or prevented by high intermittent doses of vitamin D to achieve a better treatment adherence, but treatment outcomes were contradictory, and even a transient increase in fracture and fall risk was reported.

OBJECTIVE

The objective of the study was to investigate the short-term effects on bone turnover markers of a single bolus of vitamin D₃.

DESIGN, SETTING, PATIENTS, AND INTERVENTION

Twelve elderly subjects (eight women, four men; mean age 76 ± 3 yr) were given a single oral bolus of 600,000 IU vitamin D₃. Blood samples were taken at baseline and 1, 3, 7, 14, 30, 60, and 90 d after vitamin D₃ administration. Twenty-four subjects served as controls.

MAIN OUTCOME MEASURES

Changes in serum levels of 25-hydroxyvitamin D (25OHD), 1,25-dihydroxyvitamin D, PTH, C-terminal-telopeptides of type I collagen, cross-linked N-telopeptide of type I collagen (sNTX), osteocalcin, and bone-specific alkaline phosphatase.

RESULTS

No relevant changes in 25OHD and bone turnover markers were observed in the controls. In treated subjects, serum 25OHD attained a peak increment to 67.1 ± 17.1 ng/ml (P < 0.001) at d 3. Subsequently it slowly decreased to 35.2 ± 5.8 ng/ml (P <0.01 vs. a baseline value of 21.7 ± 5.6 ng/ml). Mean serum PTH concentration decreased by 25-50% and serum 1,25-dihydroxyvitamin D rose by 25-50%. Serum CTX and sNTX rose significantly at d 1 (P < 0.01), they attained a peak increment greater than 50% at d 3, and they subsequently decreased almost back to baseline values at d 90. Serum osteocalcin slightly rose within the first 3 d and then declined by d 60. No changes were observed in serum bone-specific alkaline phosphatase.

CONCLUSIONS

Our results indicate that the use of large doses of vitamin D may be associated with acute increases in C-terminal-telopeptides of type I collagen and sNTX, which may explain the negative clinical results obtained by using intermittent high doses of vitamin D to treat or prevent vitamin D deficiency.

Bisphosphonate treatment of postmenopausal osteoporosis is associated with a dose dependent increase in serum sclerostin

The benefits coming from long-term treatment of postmenopausal osteoporosis with bisphophonates are limited by a coupled decrease in bone formation. The objective of this study is to determine whether this decrease in bone formation is associated with changes in serum levels of the WNT signaling antagonist sclerostin or Dickkopf-1 (DKK1). This is an ancillary observation from patients participating in a 12 months, phase 2, randomized clinical trial. We analyzed 107 patients given either monthly intramuscular neridronate (12.5, 25 or 50 mg) or placebo. Serum C-terminal telopeptide of type I collagen (sCTX, a bone-resorption marker) decreased by 61%, 75% and 73% in the 12.5, 25 and 50 mg dose groups, respectively. Mean changes in bone alkaline phosphatase (bAP) at 12 months were -47%, -60.0% and -52.6% in the groups receiving 12.5, 25 or 50 mg neridronate, respectively. Serum DKK1 remained unchanged at all time points in the 3 groups. Serum sclerostin increased versus placebo group gradually and significantly only in patients treated with 25 or 50 mg neridronate monthly, reaching 138-148% of baseline values (P<0.001). Changes in serum sclerostin at 12 months were negatively correlated with changes in bAP (P<0.001) even when data were adjusted for sCTX changes and only treated patients were included. In conclusions, decreased bone formation after several months of bisphosphonate therapy is associated with increased serum levels of sclerostin. This might suggest that Wnt signaling may play a role in the coupling between resorption and formation.

Circulating γδ T cells and the risk of acute-phase response after zoledronic acid administration

The use of intravenous nitrogen-containing bisphosphonates (N-BPs) is associated with the appearance of an acute phase response (APR) in a proportion of the patients for reasons that are poorly understood. The APR was attributed to the indirect activation of γδ T cells with the release of interferon-γ and tumor necrosis factor (TNF). Forty patients with postmenopausal or senile osteoporosis (age range = 53-91 years) never previously treated with intravenous (i.v.) bisphosphonate, received a single 5-mg zoledronic acid (ZOL) iv infusion over 15 minutes. White blood cells were counted and analyzed with an automated hematology analyzer (ADVIA 2120i Siemens, New York, USA) and by flow cytometer (BD FACSCanto, Becton Dickinson). The occurrence of APR was defined by the occurrence of fever (>37 °C) during the next 2 days. Forty-two percent of patients (17 of 40) receiving the infusion of ZOL experienced an APR. Compared with the others they were younger (69 ± 7 years versus 74 ± 8 years; p = 0.06), and both the proportion and absolute number of γδ T cells were significant higher (p = 0.02 and p = 0.013, respectively). Nonsignificant differences were found between the two groups for white blood cells and for the other circulating lymphocyte subpopulations. Age was inversely correlated with circulating γδ T cells (p = 0.003) but the difference between the two groups in circulating γδ T cells persisted for age-adjusted values and vice versa. In conclusion, the results of this study indicate that the number of circulating γδ T cells, together with age, are important determinant of the occurrence of APR after intravenous infusion of ZOL and possibly of any other N-BPs.

[Guidelines on prevention and treatment of vitamin D deficiency. Italian Society for Osteoporosis, Mineral Metabolism and Bone Diseases (SIOMMMS)]

The Italian Society for Osteoporosis, Mineral Metabolism and Bone Diseases (SIOMMMS) has elaborated the following guidelines about the definition, prevention and treatment of inadequate vitamin D status. The highlights are presented here. Daily vitamin D allowance ranges from 1,500 IU (healthy adults) to 2,300 IU (elderly with low calcium intake). Since the average Italian diet includes around 300 IU/day, subjects with no effective sun exposure should be supplemented with 1,200-2,000 IU vitamin D per day. The serum 25-hydroxy-vitamin D [25(OH)D] levels represents the most accurate way to assess vitamin D repletion, even though there are still no standardized assay methods. Conditions of “deficiency” and “insufficiency” are defined by the following ranges of 25(OH)D levels: less than 20 ng/ml and 20-30 ng/ml, respectively. In Italy, approximately 50% of young healthy subjects have vitamin D insufficiency during the winter months. The prevalence of deficiency increases with ageing, affecting almost all elderly subjects not on vitamin D supplements. When a condition of deficiency has been identified, a cumulative dose of 300,000-1,000,000 IU, over 1-4 weeks is recommended. In subjects recently treated for deficiency-insufficiency, a maintenance dose of 800-2,000 IU/day (or weekly equivalent) is recommended. In patients on daily doses over 1,000 IU, 25(OH)D levels should be checked regularly (e.g. once every two years). The highest tolerated daily dose has been identified as 4,000 IU/day. Vitamin D supplementation should be carefully monitored in patients at higher risk of vitamin D intoxication (granulomatosis) or with primary hyperparathyroidism. In pregnant women, vitamin D supplements should be given as in non-pregnant women, but bolus administration (i.e.: single dose >25,000 IU) should be avoided.

Bone mineral density, bone turnover markers and fractures in patients with indolent systemic mastocytosis

OBJECTIVE

We systematically assessed bone mineral density (BMD), bone turnover markers (BTM), and fractures in a large cohort of patients with Indolent Systemic Mastocytosis (ISM).

METHODS

Eighty-two patients (mean age 48 years, 37 women) with ISM were studied. BMD was measured by dual X-ray absorptiometry at the lumbar spine and proximal hip. The serum markers of bone turnover included bone-specific alkaline phosphatase, C-telopeptides of type I collagen, and serum osteocalcin. Previous clinical fractures were registered and spine X-ray was obtained from all patients.

RESULTS

Three women were excluded for concomitant diseases associated to osteoporosis. Osteoporosis according with the WHO classification (T-score<-2.5) was found in 16 patients (20.0%) (7 females and 9 men). Mastocytosis-related low BMD (Z-score at either the spine or the hip<-2) was found in 3 women (9%) and 13 men (28%). The BMD was generally lower at the spine than at the hip. No significant correlation was observed between serum tryptase levels and T or Z-score BMD. One or more moderate or severe vertebral fractures were found in 17 patients (12 men); in 11 of them Z-score values were>-2 or not valuable at the spine. No significant difference was found in the prevalence of mastocytosis-related low BMD and/or vertebral fractures between patients with or without skin involvement. Two patients had radiographic and densitometric osteosclerosis-like characteristics. In osteoporotic patients higher, normal or lower serum BTM were found, without correlations with serum tryptase levels, while in patients with osteosclerosis both BTM and serum tryptase values were particularly increased.

CONCLUSIONS

Vertebral osteoporosis and fractures are frequent in patients with ISM. Spine X-ray and densitometric examination are warranted in all patients, also without skin involvement and particularly in males; Z-score other than T-score BMD must be evaluated. Patients with idiopathic osteoporosis should be evaluated for mast cell disease. Both high than low BTM can be observed in patients with osteoporosis while osteosclerosis is characterized by high bone turnover and serum tryptase levels.

Absolute frequency spectroscopy of CO2 lines at around 2.09 μm by combined use of an Er:fiber comb and a Ho:YLF amplifier

The low-frequency tail of an octave-spanning supercontinuum (SC) generated by an Er:fiber comb is enhanced by a multipass Ho:YLF amplifier and used in a sum-frequency-generation scheme to obtain absolute referencing of a single-mode Tm-Ho:YAG laser tunable around 2.09 μm. By tuning the comb repetition frequency, the probing laser is scanned across the absorption lines of a CO(2) gas sample and highly accurate absorption profiles are measured. This approach can be readily scaled to any wavelength above ~2 μm.

High-precision molecular interrogation by direct referencing of a quantum-cascade-laser to a near-infrared frequency comb

This work presents a very simple yet effective way to obtain direct referencing of a quantum-cascade-laser at 4.3 μm to a near-IR frequency-comb. Precise tuning of the comb repetition-rate allows the quantum-cascade-laser to be scanned across absorption lines of a CO2 gaseous sample and line profiles to be acquired with extreme reproducibility and accuracy. By averaging over 50 acquisitions, line-centre frequencies are retrieved with an uncertainty of 30 kHz in a linear interaction regime. The extension of this methodology to other lines and molecules, by the use of widely tunable extended-cavity quantum-cascade-lasers, paves the way to a wide availability of high-quality and traceable spectroscopic data in the most crucial region for molecular detection and interrogation.

Long-term effects of neridronate and its discontinuation in patients with primary hyperparathyroidism

In patients with primary hyperparathyroidism (PHPT) not suitable for surgical correction, a skeletal protection with bisphosphonates is considered a reasonable option, but the long-term effects after treatment discontinuation are not well known. Sixty postmenopausal women with PHPT were given 400-600 IU vitamin D(3) daily and 100 mg neridronate IV every 2 months for 2 years with 2 additional years of follow-up without antiresorptive therapies. Bone mineral density (BMD) progressively rose by 6.7 ± 7.6% (SD) and by 2.9 ± 4.5% at the spine and femoral neck, respectively. During follow-up, mean BMD progressively fell, but after 2 years it was still 3.9 ± 5.5% higher than baseline values at the spine. Bone alkaline phosphatase and serum C-telopeptide of type I collagen decreased significantly within 6 months (28 and 49% versus baseline, respectively) and rose to baseline values within 6-12 months during follow-up. Serum PTH significantly rose from baseline during treatment, but it remained significantly higher than baseline during follow-up. The PTH changes were significantly correlated with serum 25-hydroxyvitamin D (25OHD) levels. In conclusion, in this study we observed that in patients with mild PHPT treatment with bisphosphonates is associated with the expected changes in bone-turnover markers and that the significant increases of both hip and spine BMD are partially maintained for at least 2 years after treatment discontinuation at the vertebral site. The marked increases in serum PTH levels, particularly in subjects with low 25OHD levels, persist after treatment discontinuation and this raises the suspicion that this might reflect a worsening of PHPT.

Optimising bisphosphonate treatment outcomes in postmenopausal osteoporosis: review and Italian experience

This review aims to investigate ways to optimise treatment outcomes with bisphosphonate therapy of osteoporosis in general, and in Italian clinical practice specifically. Overall, poor adherence to bisphosphonate therapy is a major limiting factor in the treatment of osteoporosis, and is associated to a large extent with gastrointestinal adverse events. An improved patient-doctor relationship and patient motivation are critical factors to improving adherence. However, other medical interventions also play a significant role. Intermittent dosing regimens decrease gastrointestinal adverse events and improve adherence, and demonstrate at least equivalent efficacy to daily regimens. Intravenous formulations also improve gastrointestinal tolerability, and are recommended in Italy for patients at high risk of this adverse event. Other recommendations in Italy to improve treatment outcomes include a case-finding approach to identify patients most suitable for bisphosphonate therapy, thus reducing the numbers needed to treat to avoid fractures. To facilitate this, a comprehensive assessment is advocated which incorporates bone mineral density, previous fractures, parental history of fractures, corticosteroid use and the presence of other diseases associated with secondary osteoporosis.

1.6-W self-referenced frequency comb at 2.06 μm using a Ho:YLF multipass amplifier

A high-power optical frequency comb at 2.06 μm has been generated using a Ho:YLF multipass amplifier seeded by the long wavelength supercontinuum tail of an octave-spanning Er:fiber comb source. The Ho:YLF amplifier showed a net gain larger than 30 dB from 2048 to 2068 nm, allowing the generation of a 20 nm bandwidth comb with a mode spacing of 100 MHz and a power per mode ranging from 20 to 370 μW. In the time domain, the amplified comb corresponds to a pulse train with 1.6 W total power and 508 fs transform-limited pulse duration. Using a self-referencing f-2f interferometer and a phase-locking loop, spectral narrowing of the offset frequency down to less than 17 Hz has been achieved.

Allergy and the bone: unexpected relationships

OBJECTIVE

To examine the relationships between allergy and bone metabolism as represented by the effects of antihistamines and leukotriene modifiers on bone resorption and formation.

DATA SOURCES

The major databases MEDLINE and Scopus were searched using the keywords bone metabolism, bone resorption, bone formation, antihistamines, h1 antagonist, leukotriene antagonist, and leukotriene modifier.

STUDY SELECTION

The studies were independently evaluated by all the coauthors, who judged their pertinence to this review.

RESULTS

Two of the most intriguing aspects in the field are the possible effects of leukotriene modifiers on fracture repair and the hypothesized role of antihistamines in contrasting osteoporosis. Another rapidly expanding field of research is that related to the immune-modulating effects of vitamin D because serum levels of vitamin D have been shown to correlate with pulmonary function, asthma onset, and the development of allergic diseases.

CONCLUSION

Although unexpected, data are now available suggesting a strict connection among allergy, its treatments, and bone metabolism.