Human osteoblast-like cell proliferation induced by calcitonin-related peptides involves PKC activity

The calcitonin peptides [calcitonin (CT), calcitonin gene-related peptide (CGRP), amylin] share many biological actions, including activity on bone cells. In the present study, CT (10(-11) to 10(-9) M) stimulated [(3)H]thymidine incorporation in primary cultures of human osteoblasts (hOB), as already demonstrated for CGRP and amylin. RT-PCR analysis showed that the calcitonin receptor and the calcitonin receptor-like receptor are both expressed in hOB. In these cells, CT (10(-10) M) and amylin (10(-9) M), in contrast to CGRP (10(-8) M), did not increase cAMP production. All three peptides stimulated protein kinase C (PKC) activity. To evaluate PKC involvement in hOB proliferation, cells were incubated with phorbol 12,13-dibutyrate, a stimulator of PKC activity; cell proliferation was increased in a dose-dependent manner (EC(50) = 3.4 x 10(-8) M). Staurosporine (10(-9) M), a PKC inhibitor, blocked phorbol 12,13-dibutyrate-induced PKC activity and cell proliferation. Inhibition of PKC by staurosporine also counteracted the stimulatory effect of CT, CGRP, and amylin on hOB proliferation. From these data, it is deduced that the activation of PKC is important for hOB proliferation and that it is involved in the anabolic effect of CT peptides on bone.

Bone effects of hexarelin, a GH-releasing peptide, in female rats: influence of estrogen milieu

OBJECTIVE

The present study was performed to evaluate the potential influence of the estrogen milieu in modulating the effects of GH/IGF stimulation by a GH-releasing peptide, hexarelin (HEXA), on bone metabolism and mineral density in middle-aged female rats.

METHODS

HEXA was administered for 60 days (50 microg/kg s.c. twice a day) to intact and ovariectomized (OVX) 11-month-old female rats and changes in bone parameters were evaluated with respect to those of the same rats under baseline conditions and with those of control rats (intact and OVX) administered isovolumetric amounts of physiological saline. Serum total alkaline phosphatase (ALP) and urinary deoxypyridinoline (Dpd) were measured before and at various times during HEXA treatment. Bone mineral content (BMC) and density of lumbar vertebrae and femoral mid-diaphyses were measured by dual energy X-ray absorptiometry before and after treatment. In all groups, serum IGF-I levels were determined before and during treatment and the GH secretory response to HEXA was assessed at the end of the experiment.

RESULTS

In intact rats, HEXA did not modify Dpd urinary excretion, induced a trend toward an increase of serum ALP activity and significantly increased BMC (+6.5%) and bone area (+4.1%) only at lumbar vertebrae. In OVX rats, HEXA did not modify the OVX-induced increase in bone turnover markers (Dpd and ALP) and did not affect the OVX-induced vertebral bone loss, but significantly increased BMC (+7.2%) and bone area (+5.3%) at femoral mid-diaphyses. HEXA significantly increased serum IGF-I levels at day 14, but not at day 60, in both intact and OVX rats, whereas the GH secretory response to HEXA was higher in the former than in the latter.

CONCLUSIONS

Overall, the present data demonstrate that chronic HEXA treatment increases BMC and bone area at lumbar vertebrae in intact rats and at femoral diaphyses in OVX rats. The different sensitivity to HEXA of the skeletal districts examined is related to the estrogen milieu and may reflect a complex interplay between estrogens and GH/IGF function.

Bone as an ion exchange system: evidence for a link between mechanotransduction and metabolic needs

To detect whether the mutual interaction occurring between the osteocytes-bone lining cells system (OBLCS) and the bone extracellular fluid (BECF) is affected by load through a modification of the BECF-extracellular fluid (ECF; systemic extracellular fluid) gradient, mice metatarsal bones immersed in ECF were subjected ex vivo to a 2-min cyclic axial load of different amplitudes and frequencies. The electric (ionic) currents at the bone surface were measured by a vibrating probe after having exposed BECF to ECF through a transcortical hole. The application of different loads and different frequencies increased the ionic current in a dose-dependent manner. The postload current density subsequently decayed following an exponential pattern. Postload increment's amplitude and decay were dependent on bone viability. Dummy and static loads did not induce current density modifications. Because BECF is perturbed by loading, it is conceivable that OBLCS tends to restore BECF preload conditions by controlling ion fluxes at the bone-plasma interface to fulfill metabolic needs. Because the electric current reflects the integrated activity of OBLCS, its evaluation in transgenic mice engineered to possess genetic lesions in channels or matrix constituents could be helpful in the characterization of the mechanical and metabolic functions of bone.

Capacity of mouse mast cells to prime T cells and to induce specific antibody responses in vivo

Mouse, human and rat mast cells have been shown to express major histocompatibility complex II molecules and present antigens to specific T-cell hybridomas in vitro. The purpose of our investigation was to determine whether mouse mast cells are able to initiate specific immune responses in vivo. Induction of anti-dinitrophenyl (DNP) immunoglobulin G1 (IgG1) and IgG2a antibodies was performed by transferring ovalbumin (OVA)-DNP-pulsed bone marrow-derived mast cells (BMMC), B cells, or macrophages into naive mice which were boosted later with soluble antigen. Cultured spleen cells from immunized mice were tested for their cytokine content. Our data show that mast cells were by far better inducers of anti-DNP IgG1 antibodies than were B cells and macrophages. In contrast, anti-DNP IgG2a response induced by macrophages was much stronger than that obtained with mast cells whereas B cells were completely unable to elicit this response. In addition to a high index of cell proliferation, spleen cells from mast cell-injected mice produced more interferon-gamma than those mice who received macrophages or B cells by two- to fivefold, and almost 10-fold, respectively. Mast cell-deficient Wf/Wf mice were compared with their normal +/+ littermates and with mast cell-reconstituted Wf/Wf mice to develop delayed-type hypersensitivity (DTH) reactions as well as humoral immune responses. Mast cell sufficient mice as well as mast cell-reconstituted Wf/Wf mice developed significantly increased DTH reactions (P = 0.02, and 0.03, respectively) and higher anti-OVA-specific antibody responses as compared with Wf/Wf mice. Our data suggest that mast cells have the potential to up-regulate both humoral and cellular immune responses in vivo.

Mast cell-dependent B and T lymphocyte activation is mediated by the secretion of immunologically active exosomes

Mitogenic activity of bone marrow-derived mouse mast cells and mast cell lines P815 and MC/9 on B and T lymphocytes is present in their culture supernatants. To identify this activity, mast cells were incubated in serum-free medium and the supernatant was subjected to differential centrifugation, which resulted in two fractions, the hypodense and dense fraction (pellet). When analyzed for their mitogenic activity on spleen cells, all activity was found to be associated with the dense fraction. Electron microscopy studies revealed the presence in this fraction of small vesicles called exosomes with a heterogeneous size from 60 to 100 nm of diameter. When cocultured with spleen cells, purified exosomes induced blast formation, proliferation, as well as IL-2 and IFN-gamma production, but no detectable IL-4. Similar data were obtained by injecting exosomes into naive mice. In contrast to mast cell lines, a pretreatment with IL-4 is required for bone marrow-derived mast cells to secrete active exosomes. Structurally, exosomes were found to harbor immunologically relevant molecules such as MHC class II, CD86, LFA-1, and ICAM-1. These findings indicate that mast cells can represent a critical component of the immunoregulatory network through secreted exosomes that display mitogenic activity on B and T lymphocytes both in vitro and in vivo.

Nonspecific B and T cell-stimulatory activity mediated by mast cells is associated with exosomes

Bone marrow-derived mouse mast cells (BMMC) and mast cell lines P815 and MC9 have recently been shown to induce antigen-independent B and T lymphocyte activation. It has been demonstrated that a physical contact between mast cells and B and T lymphocytes is not necessary since mast cell supernatants contain full activity. Electron microscopy studies revealed the presence in mast cell supernatants of small vesicles called exosomes with a heterogeneous size from 60 to 100 nm of diameter. When cocultured with spleen cells, purified exosomes induce B and T cell blast formation, proliferation as well as IL-2 and IFN-gamma production. In contrast to P815 and MC9 mast cell lines, a pretreatment with IL-4 is required for BMMC to produce active exosomes. Structurally, these exosomes were found to harbor immunologically relevant molecules such as MHC class II, CD86, LFA-1 and ICAM-1. Here we provide for the first time the evidence that mast cells use exosomes as sophisticated messengers to communicate with cells of the immune system.

Effects of calcitonin gene-related peptide and amylin on human osteoblast-like cells proliferation

Expression of mRNA for calcitonin gene-related peptide (CGRP) and CGRP receptor has been detected in osteoblasts indicating that CGRP could play a role in bone metabolism. In the present study, we evaluated the effect of CGRP on primary culture of human osteoblast-like cells proliferation. The peptide was able to stimulate [3H]thymidine incorporation in human osteoblast-like cells with a maximal effect at 10(-8) M. The proliferating activity of CGRP was not inhibited by the two antagonists, CGRP-(8-37) or amylin-(8-37), whereas amylin fragment antagonized the proliferating activity of amylin. In human osteoblast-like cells CGRP, but not amylin, was able to stimulate adenylyl cyclase activity and this effect was completely antagonized only by CGRP-(8-37) and not by amylin-(8-37). These data suggest that the CGRP induced stimulation of cAMP is not involved in the peptide proliferating effect in human osteoblast-like cells and that in this cell population there are receptor subtypes for CGRP, distinct from that of amylin.

Bone as an ion exchange system: evidence for a pump-leak mechanism devoted to the maintenance of high bone K(+)

To provide evidence of active accumulation of K(+) in bone extracellular fluid (BECF), electric currents driven by damaged living metatarsal bones of weanling mice, immersed in physiological media at different [K(+)], in the presence of blockers of the K(+) channels or of the Na(+)-K(+-)ATPase inhibitor, were measured by means of a voltage-sensitive two-dimensional vibrating probe. At 4 mM extracellular K(+) concentration ([K(+)](o)), an inward steady current density (7.85-38.53 microA/cm(2)) was recorded at the damage site, which was significantly dependent on [K(+)](o). At [K(+)](o) equal to that of BECF (25 mM), current density was reduced by 76%. At [K(+)](o) of 0 mM, the current density showed an increase, which was hindered by tetraethylammonium (TEA). Basal current density was reduced significantly after exposure to TEA or BaCl(2) and was unchanged after long- term exposure to ouabain. By changing control medium with a chloride-free medium, current density was reversed. The results support the view that K(+) excess in bone is maintained by a biologically active cellular system. Because the osteocyte-bone lining cell syncytium was at the origin of the current in bone, it is likely that this system controls the ionic composition of BECF.

In vitro and in vivo immunostimulatory potential of bone marrow-derived mast cells on B- and T-lymphocyte activation

BACKGROUND

Mast cells, which play a unique role in inflammatory and allergic responses, have also been shown to actively participate to the build-up of protective host defense mechanisms. Recently, they have been shown to stimulate resting B cells and to form heterotypic aggregates with activated T cells, resulting in mast cell degranulation.

OBJECTIVES

Our aim is to investigate the cytokine requirements and the mechanisms by which murine mast cells activate resting B and T lymphocytes.

METHODS

Mouse bone marrow-derived mast cells (BMMCs) or peritoneal mast cells were cocultured with resting splenocytes. Activation of B and T lymphocytes was assessed by measuring cell proliferation, blast formation, and cytokine release.

RESULTS

We report that addition of IL-4-treated BMMCs to normal spleen cells resulted within 48 hours in a B- and T-cell activation with substantial amounts of the T(H1) cytokines IFN-gamma and IL-12 and no detectable IL-4. We also demonstrate that mature mast cells in the peritoneal cavity are able to induce spleen cell activation and cytokine release. Addition of antileukocyte function-associated antigen 1 and anti-intercellular adhesion molecule 1 to the cocultures completely abrogates mast cell-induced blast formation and cytokine release. Experiments performed in vivo indicate that spleen cells from mice injected with BMMCs sustain their capacity of proliferation and cytokine production in vitro without any further stimulation.

CONCLUSION

These observations suggest that mast cells may exert a helper effect on B and T lymphocytes, initiate T(H1)-type immune responses, and may participate, through this mechanism, in the downregulation of allergic responses.

Total and free deoxypyridinoline after acute osteoclast activity inhibition

BACKGROUND

Deoxypyridinoline (Dpd) is one of the two pyridinium cross-links that provide structural rigidity to type I collagen in bone. During osteoclastic resorption, Dpd is released into circulation and is excreted in the urine in free and peptide-bound forms. Free and total Dpd are highly correlated, but whether the free-to-total cross-link ratio is constant in both normal and high bone turnover states remains controversial. To compare free and total Dpd performance in a physiological condition, urinary free and total Dpd were measured after a short-term inhibition of osteoclast activity such as that induced by an oral calcium load.

METHODS

Total and free Dpd were measured by HPLC and by immunosorbent assay, respectively, in two groups of subjects, one (calcium-treated; n = 16) taking calcium and the other not (control; n = 9).

RESULTS

The urinary excretion of total Dpd at 2 and 4 h after oral calcium loading was decreased compared with controls. By contrast, changes in free Dpd were similar in the calcium-treated and control groups, reflecting only circadian rhythm.

CONCLUSIONS

Total and free Dpd do not show comparable sensitivity in detecting short-term inhibition of osteoclast activity. The degradation process of peptide-bound to free Dpd could render free Dpd insensitive to acute changes of osteoclast activity.

FcepsilonRI-mediated antigen endocytosis turns interferon-gamma-treated mouse mast cells from inefficient into potent antigen-presenting cells

Previous studies in our laboratory have shown that bone-marrow-derived mast cells (BMMC) could present immunogenic peptides, from soluble antigens endocytosed through fluid phase, only if they were subjected to a 48-hr treatment with interleukin-4 (IL-4) and granulocyte-macrophage colony-stimulating factor (GM-CSF). In contrast to GM-CSF, interferon-gamma (IFN-gamma) which highly upregulates major histocompatibility complex (MHC) class II expression, completely inhibits the generation of immunogenic peptides. We have used this model to study the role of FcepsilonRI-mediated antigen internalization in the regulation of the antigen-presenting function of IFN-gamma-treated mast cells. Here, we report that FcepsilonRI can reverse the IFN-gamma-treated mast cells from inefficient to highly efficient antigen-presenting cells. Inhibition of the antigen presenting capacity by piceatannol, a protein tyrosine kinase (PTK) syk inhibitor, indicates that this is an active process resulting from immunoglobulin E (IgE)-antigen-FcepsilonRI engagement which involves tyrosines found in the immunoreceptor tyrosine-based activation motif (ITAM) embedded in the cytoplasmic tail of the FcepsilonRI beta and gamma chains. Antigen-presenting function was also shown to require the activation of phosphatidyl inositol 3 (PI3) kinase, downstream of PTK syk phosphorylation, since this activity was completely blocked by wortmannin, a PI3 kinase inhibitor. These data suggest that signalling generated by FcepsilonRI provides mast cells with IgE-mediated enhanced antigen presentation to T cells and emphasize a so far unknown immunoregulatory mast-cell function that might take place in inflammatory sites.

Osteocyte-bone lining cell system at the origin of steady ionic current in damaged amphibian bone

A wound-generated steady electric current was measured by a two-dimensional vibrating probe system in the metatarsal bones of 22 adult frogs (Xenopus laevis) placed in amphibian Ringer. Inward currents were recorded entering a micrometric hole drilled through the cortex at middiaphyseal level. These steady state currents (mean +/- SD 8.50 +/- 2.77 microA/cm2) last approximately 2 hours, were dependent on the presence of sodium in the incubation medium, were no more detectable after fixation, and were reduced to background level when the cell membranes were solubilized. These results agree with previous recordings of metatarsal bones of weanling mice, under identical conditions. Both results suggest that the measured ionic currents have a cellular origin. Metatarsal bones of adult amphibian were purposely selected for this study because, unlike mammalian bones, their shafts are avascular and only contain an osteocyte-bone lining cell system, as documented by scanning and transmission electron observations. Thus, unlike the data from previous investigations on mammals, the results succeeded in giving the first convincing evidence that the osteocyte-bone lining cell system is the origin of damage-generated ionic currents. As damage exposes bone ionic compartment to plasma, damage-generated ionic currents are representative of ion fluxes at bone plasma interface, and cells at the origin of the current generate the driving force of such fluxes. By demonstrating that osteocytes and bone lining cells are at the origin of the current, this study suggests that the osteocyte-bone lining cell system, though operating as a cellular membrane partition, regulates ionic flow between bone and plasma. Since strain-related adaptive remodeling could also depend on ionic characteristics and flow of the bone fluid through the osteocyte lacuno-canalicular network, the results reported here support the view that osteocyte and bone lining cells may constitute a functional syncytium involved in mineral homeostasis as well as in bone adaptation to mechanical loading.

[Child obesity in Navarra: evolution, tendency and relation between child and adult obesity. Pecna study]

INTRODUCTION

Excess of weight at an adult age is linked to an increased risk of dying. Obesity during childhood has been increasing in recent years in the developed countries. The aim of this study is to determine the prevalence of obesity in an infant-youth population of Navarra and its follow up over six years.

MATERIAL AND METHODS

Longitudinal study of a cohort formed by 1,164 children of both sexes of 4, 10 and 17 years of age at the start of the study, with data collection in 1987 and 1993. Obesity was calculated using the Index of Corporal Mass or Quetelet Index (QI) higher than percentile 90 for their age and sex.

RESULTS

The rate of response obtained was 63.3% (n=737). Between 1987 and 1993 there was an increase of 5% in the obese population (p<0.01). There is a significant correlation (r=0.72) between the values of the QI at the start of the study and those obtained at its conclusion. Some 61.4% of the individuals belonging to the higher quintile of the sample at the start of the study continued belonging to this quintile after six years of follow up.

CONCLUSIONS

There was an increase in obesity, in correspondence with the findings of similar studies. There is good "tracking" between obesity during childhood and its presence at an adult age. The strategies for prevention of obesity must start from infancy.

A one-million-year-old Homo cranium from the Danakil (Afar) Depression of Eritrea

One of the most contentious topics in the study of human evolution is that of the time, place and mode of origin of Homo sapiens. The discovery in the Northern Danakil (Afar) Depression, Eritrea, of a well-preserved Homo cranium with a mixture of characters typical of H. erectus and H. sapiens contributes significantly to this debate. The cranium was found in a succession of fluvio-deltaic and lacustrine deposits and is associated with a rich mammalian fauna of early to early-middle Pleistocene age. A magnetostratigraphic survey indicates two reversed and two normal magnetozones. The layer in which the cranium was found is near the top of the lower normal magnetozone, which is identified as the Jaramillo subchron. Consequently, the human remains can be dated at approximately 1 million years before present.

[Lipidic profile: evolution, tendency and tracking from infancy to adulthood. PECNA Study]

Cardiovascular diseases start during infancy, although the clinical manifestations show themselves during adulthood. Since the year 1987 a (PECNA) study has been underway in Navarra to analyse the epidemiology of the cardiovascular risk factors of the infant-juvenile population. This paper presents the evolution of the lipidic profile from 4 to 23 years of age, the tendency from 1987 to 1993, the evolution of the prevalence of hypercholesterolaemia seric cholesterol >200 mg/dl and the tracking from infancy to adult age. Outstanding amongst the results are the differences between the lipidic profile in both sexes, as well as the observed fall in the average levels of total seric cholesterol and in the prevalence of hypercholesterolaemia. With regard to the tracking, it is concluded that between 50% and 55% of individuals belonging to the extreme quintile of the distribution of the lipidic variables persist at this level six years later.

Methotrexate therapy in refractory pediatric onset systemic lupus erythematosus

OBJECTIVE

To evaluate the efficacy, safety, and corticosteroid sparing potential of methotrexate (MTX) in patients with pediatric onset systemic lupus erythematosus (SLE).

METHODS

The medical records of 11 patients with SLE with onset before age 16 years were reviewed. Details of clinical features, previous therapy, indications for MTX, efficacy, toxicity, and corticosteroid reduction during MTX therapy were recorded.

RESULTS

At the start of MTX treatment, 7 patients had nephritis, 3 malar rash, 3 arthritis, 2 skin vasculitis, and 2 thrombocytopenia. All patients were given MTX (12.5-17.0 mg/m2/week) as the sole drug therapy along with prednisone. Although many patients showed initial improvement and/or were able to reduce the prednisone dose, after 7 to 23 months 8 patients had a flare of SLE requiring increased doses of prednisone, one patient had unchanged SLE activity, and 2 patients were permanently discontinued from MTX because of toxicity. Side effects were observed in 8 (73%) patients, but only 2 (18%) discontinued MTX due to toxicity.

CONCLUSION

MTX given as the sole drug therapy along with prednisone did not show a major corticosteroid sparing potential in our patients with pediatric onset SLE.

Responsiveness of urinary markers of bone resorption to orchiectomy and clodronate treatment in mature rats: a comparative study

OBJECTIVE

The aim of this study was to assess the responsiveness of two classes of bone resorption markers to the enhancement of osteoclastic activity induced by orchiectomy and to its inhibition by clodronate treatment in mature rats.

DESIGN

Bone mineral density (BMD) at femural metaphysis, femural diaphysis, lumbar vertebrae, and the urinary excretion of pyridinoline (Pyr), deoxypyridinoline (D-Pyr), galactosylhydroxylysine (GHyl) and glucosylgalactosylhydroxylysine (GGHyl) were monitored at regular intervals for 30 days prior to and for 60 days following orchiectomy in eleven rats, divided into two groups: five rats untreated and the other six treated with clodronate.

RESULTS

Prior to orchiectomy, a significant (P < 0.01) decrease in BMD was observed only at the distal femural metaphysis. This decrease appeared to be associated with a time-dependent increase in the urinary excretion of all markers. Following orchiectomy, the BMD of the untreated group decreased significantly (P < 0.01) at all bone sites. The bone loss was accompanied by a significant (P < 0.01) increase in Pyr and D-Pyr concentrations in urine, whereas urinary GHyl and GGHyl did not change significantly. In the clodronate-treated group, the BMD of the three skeletal sites did not change significantly, while the urinary excretion of all urinary biochemical markers decreased significantly (P < 0.001).

CONCLUSION

This study showed that pyridinolines are able to monitor the bone response to orchiectomy and to clodronate treatment response in androgen-deficient mature male rat. whereas glycosides appear prone to confounding factors.

Effects of amylin on human osteoblast-like cells

Amylin has been reported to have bone-conserving effects. In the present study we evaluated the possible activity of the peptide on human osteoblast-like (hOB) cells in primary culture. Amylin between 10(-9) and 10(-6) M, dose-dependently stimulated cell proliferation with a maximal effect (200%) at 10(-6) M. In addition, amylin increased osteocalcin production when hOB cells were exposed to 1,25(OH)2D3 (10(-8)M) but there was a nonsignificant upward trend on alkaline phosphatase activity. The present results suggest that amylin could be included among the group of peptides endowed with osteogenic activity.

Comparison between urinary pyridinium cross-links and hydroxylysine glycosides in monitoring the effects of ovariectomy and 17 beta-estradiol replacement in aged rats

This study was undertaken to assess the sensitivity of hydroxylysylpyridinoline (HP), lysylpyridinoline (LP), galactosylhydroxylysine (GHyl) and glucosylgalactosylhydroxylysine (GGHyl) to monitor bone response to estrogen deficiency and replacement by comparing their excretory patterns in ovariectomized aged (11-14 months old) rats. The ovariectomized (OVX) rats were randomized into two groups: (1) OVX plus vehicle; (2) OVX plus 17 beta-estradiol (17-beta E, 10 micrograms/kg, s.c., 4 days/week). Treatment with 17-beta E started immediately after OVX and continued for 60 days. The collagen catabolites were measured in urine for 1 month before OVX and thereafter for 60 days. In temporal coincidence with urine collection, bone area and bone mineral density (BMD) of lumbar vertebrae, femoral diaphysis and distal metaphysis were measured by dual-energy X-ray absorptiometry. In the untreated rats, BMD of the femoral metaphysis and lumbar vertebrae decreased significantly and the urinary excretion of LP, HP, GHyl and GGHyl increased with different patterns. In the treated rats, 17-beta E replacement prevented the increment in LP excretion, partially prevented the increase in HP excretion, but had no effect on the excretion of GHyl and GGHyl. In conclusion pyridinolines and glycosides have different sensitivities to the bone response to OVX. Glycoside excretion after OVX also reflects metabolic processes not strictly related to bone loss and, in contrast with LP, is not sensitive to estrogen replacement.

Osteocalcin production in vivo and in vitro after 1,25-dihydroxycholecalciferol stimulation comparison of different assays

The study was designed to assess the sensitivity of three commercial assays (which differ in methodology, standard and antibodies) for osteocalcin, used for detecting changes in osteocalcin secretion induced by calcitriol (1,25-dihydroxycholecalciferol) in vivo and in vitro. Osteocalcin levels were determined in serum samples of 10 osteoporotic women after short term calcitriol treatment, and in the culture medium of human osteoblast-like cells (n = 22) after 48 h calcitriol exposure. All assays displayed similar sensitivity in detecting osteocalcin production in vivo after a 1 microgram daily dose of calcitriol. A novel IRMA (CIS), claimed to detect intact osteocalcin, showed higher osteocalcin values than the other assays, and in vitro showed the best sensitivity; it provides an appropriate index of the osteocalcin synthetic activity of cultured human osteoblasts.

Pulmonary function in children with systemic lupus erythematosus

BACKGROUND

Abnormalities of pulmonary function have been found in children with systemic lupus erythematosus (SLE) even in the absence of clinical or radiographic evidence of pulmonary involvement. It is unknown whether these abnormalities represent an early sign of progressive lung disease or whether they are associated with disease activity.

METHODS

After a mean of 4.5 years, respiratory function (forced vital capacity (FVC) and single breath gas transfer factor (TLCO)) and disease activity were reexamined in 13 of 15 previously studied children with SLE. Disease activity was assessed by a validated index of SLE activity (SLE activity measure (SLAM)).

RESULTS

In spite of the high prevalence of abnormalities of respiratory function at the baseline investigation, no chest radiographic abnormalities or overt clinical signs of lung disease were found at baseline, in the interval between the two investigations, or at the re-evaluation in any patient. From baseline to the second investigation the mean value of SLAM decreased and there was a trend toward an improvement in FVC and TLCO. TLCO was more severely impaired than FVC, being found as an isolated abnormality in a high percentage of patients (45% at baseline and 35% at follow up). There was a relationship between baseline TLCO and disease activity, expressed as a SLAM score. Moreover, there was a correlation between the changes in the SLAM score from baseline to the second investigation and the corresponding changes in the TLCO value, but not with the corresponding changes in the FVC value.

CONCLUSIONS

In this series of patients the decrease in SLE activity from the first to the second investigation was associated with an improvement in pulmonary function. The presence of early isolated functional abnormalities was not associated with subsequent development of lung disease.

Differential effects of CGRP on adenylyl cyclase in adult and embryonic rat brain

The presence of functional receptors for calcitonin gene-related peptide (CGRP) in the brain of adult rats and on nerve cell cultures was investigated. Neuronal and glial cultures were obtained from mesencephalons of embryos at gestational day 16. The response to CGRP was tested by measuring the adenylyl cyclase (AC) activity on isolated membranes. CGRP binding in adult rat brains was ineffective in activating AC, whereas a dose-dependent stimulation of AC activity was induced by the peptide both in neuronal and glial cultures. This effect was more pronounced in the glial cells where high affinity binding sites for CGRP were detected. The presence of functional CGRP receptors in embryonic mesencephalic cells, suggests a role for CGRP in the development of rat mesencephalon.