Measuring Stokes parameters by means of a polarization grating

Ordinary gratings act on the amplitude and (or) the phase of a wave front. Polarization gratings produce instead a periodic modulation of the state of polarization. A simple grating of the latter type is constituted by a linear polarizer whose orientation varies periodically along a line. It is shown that, for a generic polarization state of the incident field, such a grating gives rise to first-order diffracted beams with counterrotating circular polarizations. It is also shown that such a grating can be used for measuring the Stokes parameters of a light beam in an achromatic manner. Several extensions are briefly discussed.

Leptin acts on human marrow stromal cells to enhance differentiation to osteoblasts and to inhibit differentiation to adipocytes

Both bone mass and serum leptin levels are increased in obesity. Because osteoblasts and adipocytes arise from a common precursor in bone marrow, we assessed the effects of human recombinant leptin on a conditionally immortalized human marrow stromal cell line, hMS2-12, with the potential to differentiate to either the osteoblast or adipocyte phenotypes. By RT-PCR and Western immunoblot analysis, the hMS2-12 cells expressed messenger RNA (mRNA) and protein for the leptin receptor. Leptin did not affect hMS2-12 cell proliferation, but resulted in dose- and time-dependent increases in mRNA and protein levels of alkaline phosphatase, type I collagen, and osteocalcin, and in a 59% increase in mineralized matrix. Leptin increased mRNA levels of lipoprotein lipase at 3 days, but decreased mRNA levels of adipsin and leptin at 9 days and decreased lipid droplet formation by 50%. Leptin did not affect the expression of Cbfa1 or peroxisome proliferator-activated receptor-gamma2, transcription factors involved in commitment to the osteoblast and adipocyte pathways, respectively. Thus, leptin acts on human marrow stromal cells to enhance osteoblast differentiation and to inhibit adipocyte differentiation. Our data support the hypothesis that leptin is a previously unrecognized, physiological regulator of these two differentiation pathways, acting primarily on maturation of stromal cells into both lineages.

Duplex scanning exploration of the ophthalmic artery for the detection of the hemodynamically significant ICA stenosis

BACKGROUND AND PURPOSE

The North American and the European Carotid Endarterectomy Trials demonstrated a significant benefit of surgery in preventing stroke for patients with symptomatic hemodynamically significant internal carotid artery (ICA) stenosis. Because the 3 angiographic methods of measuring carotid stenosis provide discrepant results, the indication for surgery depends on the method used for the evaluation of the angiogram. The goal of this study was to verify whether color duplex scanning of the ophthalmic artery alone might be reliable for detection of the extracranial hemodynamically significant ICA stenosis.

METHODS

Three groups of patients (351 total patients) with transient ischemic attack or minor stroke referred for possible carotid endarterectomy were examined by means of color duplex scanning of the ICA, transcranial Doppler, color duplex scanning of the ophthalmic artery, and angiography of the ICA.

RESULTS

In the first group (n=31) the comparison of findings from each method and the direct measurement of the residual lumen of plaque removed "en bloc" showed that the findings of the ophthalmic artery color duplex scanning, subdivided into 5 categories--NP (normal positive), LP (low positive), NF (no flow), REV (reverse flow), PP (pathological positive)--were associated with the best overall agreement (96.7%). The accuracy of the various categories of the ophthalmic artery color duplex scanning signals was studied in the second group of patients (n=200). The results pointed out that all but low positive categories were associated with high diagnostic accuracy. Finally, the results obtained in the third group (n=120) showed that a significant increase in the specificity of the low positive signal could be obtained by processing this signal in terms of pulsatility index and of transmission of pulsatility index.

CONCLUSIONS

Our results suggest that the diagnostic capacity of color duplex scanning for the detection of ICA critical stenosis can be appropriately increased if it is performed also at the level of the ophthalmic artery and if the Doppler signals are processed on the basis of criteria we applied.

Leptin acts on human marrow stromal cells to enhance differentiation to osteoblasts and to inhibit differentiation to adipocytes

Both bone mass and serum leptin levels are increased in obesity. Because osteoblasts and adipocytes arise from a common precursor in bone marrow, we assessed the effects of human recombinant leptin on a conditionally immortalized human marrow stromal cell line, hMS2-12, with the potential to differentiate to either the osteoblast or adipocyte phenotypes. By RT-PCR and Western immunoblot analysis, the hMS2-12 cells expressed messenger RNA (mRNA) and protein for the leptin receptor. Leptin did not affect hMS2-12 cell proliferation, but resulted in dose- and time-dependent increases in mRNA and protein levels of alkaline phosphatase, type I collagen, and osteocalcin, and in a 59% increase in mineralized matrix. Leptin increased mRNA levels of lipoprotein lipase at 3 days, but decreased mRNA levels of adipsin and leptin at 9 days and decreased lipid droplet formation by 50%. Leptin did not affect the expression of Cbfa1 or peroxisome proliferator-activated receptor-gamma2, transcription factors involved in commitment to the osteoblast and adipocyte pathways, respectively. Thus, leptin acts on human marrow stromal cells to enhance osteoblast differentiation and to inhibit adipocyte differentiation. Our data support the hypothesis that leptin is a previously unrecognized, physiological regulator of these two differentiation pathways, acting primarily on maturation of stromal cells into both lineages.

Aromatase expression and activity in the human leukaemic cell line FLG 29.1

The recent observation that estrogen synthesis occurs in osteoblast-like cells has suggested the aromatase activity as a possible local modulator of bone remodeling in post-menopausal women. To provide further insights into the androstenedione conversion to estrogen in bone-derived cells, we examined the human leukaemic cell line FLG 29.1, which is induced to differentiate toward the osteoclastic phenotype by TPA and TGF-beta1. Southern blot of RT-PCR products with a 32P-labeled cDNA probe for the human aromatase demonstrated that FLG 29.1 cells express aromatase mRNA. The enzyme activity, determined by measuring [3H]H2O release from [3H]androstenedione, obeyed Michaelis-Menten kinetic with apparent Km and Vmax values ranging from 5 to 10 nM and from 200 to 400 fmol/mg protein/6 h. Gene expression, enzyme activity and protein immunoreactivity, evaluated by immunocytochemistry, were stimulated in a time-dependent fashion by 5% charcoal-stripped FCS and by either 1-100 nM TPA or 0.01-0.5 ng/ml TGF-beta1, with maximal responses after 2-3 h exposure. After 24 h incubation of FLG 29.1 cells in the absence of these stimuli the aromatase mRNA and the protein were barely detectable. These findings demonstrate that cells of the osteoclastic lineage synthesize estrogen in vitro and that local cytokines, such as TGF-beta1, are able to induce androstenedione conversion.

Intensity-based modal analysis of partially coherent beams with Hermite-Gaussian modes

Many partially coherent beams are made up of a superposition of mutually uncorrelated Hermite-Gaussian modes. We prove that knowledge of the transverse intensity profile of such a beam is sufficient for evaluating the weights of the modes in an exact way. Simulations indicate that the proposed method resists noise well.

Matrix treatment for partially polarized, partially coherent beams

A matrix method is outlined for dealing with quasi-monochromatic, partially polarized light when spatial coherence is not necessarily complete and propagation occurs along beams. Both spatial coherence and polarization properties are described by a single 2x2 matrix whose elements have the structure of mutual intensity functions. Through a simple example it is shown that this matrix can account for differences that would not be revealed by a scalar treatment or by a locally defined polarization matrix.

Development and characterization of conditionally immortalized osteoblast precursor cell lines from human bone marrow stroma

Although the differentiation of mature osteoblasts has been well studied, there is still a need for a convenient way to study preosteoblast differentiation. Our laboratory has recently described a method for isolating small numbers of authentic osteoblast precursor cells from human bone marrow (Rickard et al., J Bone Miner Res 11:312-324, 1996). Here we describe the conditional immortalization of these cells by retroviral transfection with the amphotrophic vector, pZipSV40tsa58, which encodes for a temperature-sensitive mutant form of the simian virus large T-antigen. At the permissive temperature of 34 degrees C, the cell lines proliferated, but differentiation was arrested, whereas at the restrictive temperature of 39.5 degrees C, proliferation was decreased and differentiation was induced. As assessed by semiquantitative reverse transcriptase PCR after 4 days of culture at 39.5 degrees C, the six cell lines expressed similar mRNA levels both constitutively and in response to dexamethasone (Dex) and 1alpha,25-dihydroxyvitamin D3 (1,25(OH2)D3) for osteoblast (alkaline phosphatase [ALP], type I collagen [Col I], osteocalcin [OC], and parathyroid hormone receptor [PTH-R] and adipocyte (lipoprotein lipase [LPL]) genes. In the presence of 10(-8) M Dex, gene expression for ALP, PTH-R, and LPL increased, but that for OC decreased. Stimulation with 10(-8) M 1,25(OH2)D3 increased gene expression for ALP, OC, and Col I. Changes in protein production for ALP, OC, and type I procollagen in response to Dex and 1,25(OH2)D3 were similar to changes in mRNA levels. When cultured at 39.5 degrees C with ascorbate and beta1-glycerolphosphate for 21 days, mineralization of matrix occurred, whereas culture with Dex plus 1,25(OH2)D3, or rabbit serum led to enhanced formation of cytoplasmic lipid droplets within 6 days. Thus, these cell lines are capable of bipotential differentiation and should serve as an excellent tool to study the molecular mechanisms that regulate and select for osteoblast and adipocyte differentiation in humans.

Bone morphogenetic protein-6 production in human osteoblastic cell lines. Selective regulation by estrogen

Bone morphogenetic proteins (BMPs) induce differentiation of osteoblast and chondroblast lineage cells from uncommitted mesenchymal precursors. Because estrogen has potent osteochondrogenic actions, we investigated its effect on BMP production in two estrogen-responsive, human immortalized cell lines (hFOB/ER3 and hFOB/ER9) that display the mature osteoblast phenotype. These cell lines were produced by stable transfection of the estrogen receptor (ER) gene into immortalized fetal osteoblasts at low ( approximately 800 ER/ nucleus) and at high ( approximately 3, 900 ER/nucleus) levels, respectively. As assessed by reverse transcriptase PCR, treatment with 17beta-estradiol (10(-)10 - 10(-)7 M) increased steady-state levels of BMP-6 mRNA dose dependently by twofold in the hFOB/ER3 cells and by over threefold in the hFOB/ER9 cells. Messenger RNA levels for transforming growth factors-beta1 and -beta2 and BMPs-1 through -5 and -7 levels were unchanged. The results were confirmed by sequence determination of the PCR product and by Northern blot analysis for total RNA. 17beta-estradiol increased BMP-6 protein production sixfold by Western analysis. Cotreatment with antiestrogens (ICI 182,780 or 4-hydroxytamoxifen) antagonized the effects of 17beta-estradiol. These data suggest that some of the skeletal effects of estrogen on bone and cartilage may be mediated by increased production of BMP-6 by osteoblasts.

Heterogeneity of binding sites and bioeffects of raloxifene on the human leukemic cell line FLG 29.1

The benzothiophene divarative raloxifene is known to mimic estrogen in human bone remodeling. To investigate the "in vitro" properties of raloxifene on osteoclast precursors, the human leukemic cell line FLG 29.1, which differentiates toward the osteoclastic phenotype, was examined for raloxifene binding and for evidence of its bioeffects. Scatchard and Hill analysis of binding data with the tritiated raloxifene demonstrated the presence of two classes of binding sites in both nuclear and cytosol fractions with Kd values of approximately 1 nM and approximately 5 nM, respectively. In addition, analysis of binding data using tritiated 17 beta E2 as ligand at high concentrations (10-40 nM) and either unlabeled 17 beta E2 or raloxifene as competitors gave similar results demonstrating the presence of type II EBS in these cells. Picomolar concentrations of raloxifene significantly (p < 0.05) inhibited cell proliferation. Moreover, the compound at nanomolar concentrations induced a significant dose- and time-dependent increase of progesterone receptor, and activated apoptotic cell death. These findings clearly demonstrate that raloxifene acts as an estrogen agonist in FLG 29.1 cells, acting through the estrogen receptor and, possibly, via multiple cooperative binding component(s).

[The reactive and/or repair role of the smooth muscle cells in Horton's arteritis]

A recent view of atherosclerosis indicates vascular smooth muscle cell proliferation not only as a response-to-injury but also as an essential reparative process leading to plaque stabilization. To assess the role of vascular smooth muscle cell in vasculitides we studied, as a model, 10 cases of Horton's arteritis. In particular, we investigated by immunohistochemical analysis cellular population and proliferation rate in the intimal layer. As in atherosclerotic plaques, intimal thickening in arteritis is essentially due to proliferation and migration of vascular smooth muscle cells. We suppose that, whatever the vascular disease, intimal hyperplasia contributes to stability of the vessel's wall; however the reactive/reparative process is extremely slow in spontaneous atherosclerosis, accelerated in arteritis.

[Sarcoidosis with predominant cardiac involvement]

We present a case of predominantly myocardial sarcoidosis in a 38 year-old man. A second degree atrioventricular block was the clinical presentation, followed 2 years later by sudden cardiac arrest. Autopsy revealed large areas of myocardial scarring in the left ventricular wall unassociated with atherosclerotic coronary lesions; microscopy of these areas disclosed epithelioid granuloma with giant cells embedded in a fibrohyaline tissue. The insidious cardiac involvement in sarcoidosis often hinders an exact diagnosis in life, and prognosis without therapy is severe. Histopathologic diagnosis is made only by exclusion of other systemic granulomatous diseases.

[Coronary embolism and myocardial infarction with heat rupture during infectious endocarditis]

We report a case of transmural myocardial infarction due to coronary embolism complicating infective endocarditis in a 41 year old woman. The infarction, clinically silent, was followed by rupture of left ventricular free wall, leading to hemopericardium and cardiac tamponade. The case is an uncommon complication of infective endocarditis, at the same time an uncommon cause of myocardial infarction.

Membrane binding sites and non-genomic effects of estrogen in cultured human pre-osteoclastic cells

Besides functional estrogen receptors, the presence of signalling cell surface binding sites for 17beta-estradiol (17betaE2) has been reported in osteoblast- and osteoclast-like cells, suggesting that 17betaE2 may influence bone remodelling by a dual mechanism of action: to affect gene expression mediated by the nuclear activity of the steroid-receptor complex, and to initiate rapid responses triggered by a signal-generating receptor on the cell surface. Recently, we demonstrated that the human pre-osteoclastic cell line FLG 29.1 bears functional estrogen receptors. In this study we examined FLG 29.1 cells for the presence of cell surface binding sites for 17betaE2, and whether 17betaE2 could elicit cell signalling. Using a cell-impermeant and fluorescent estrogen conjugate, 17beta-estradiol-6-carboxymethyloxime-bovine serum albumin-fluorescein isothiocyanate, we demonstrated the presence of specific plasma membrane binding sites for 17betaE2. Stimulation of FLG 29.1 cells with low (1 nM) and high (1 microM) doses of 17betaE2 induced a prompt and significant (P < 0.05) increase of cellular pH, as measured in single cells using an image analysis system. In addition, both cAMP and cGMP were significantly increased by 17betaE2 with a dose-dependent response. Finally, a rapid increase of intracellular calcium ion concentration [Ca2+] was also induced by 1 nM 17betaE2, as measured in single cells using an image analysis system. Our findings strongly suggest a non-genomic action of 17betaE2 on osteoclast precursors.

Shape-invariance range of a light beam

A typical axially symmetric light beam on paraxial free propagation maintains the same transverse shape as at the waist plane for a certain range along its axis. We discuss a general procedure for estimating this range.

Characterization and function of the receptor for IGF-I in human preosteoclastic cells

Using a coculture system, we have recently demonstrated that insulin-like growth factor I (IGF-I) is a mediator of preosteoclastic cell migration toward bone-derived endothelial cells. To better characterize the mechanisms of IGF-I action on preosteoclastic cells we evaluated the expression of type I IGFs receptor in the human leukemic cell line, FLG 29.1, which differentiates toward the osteoclastic phenotype following phorbol ester (TPA) treatment. Scatchard analysis of 125I-labeled IGF-I to FLG 29.1 cells revealed the presence of a single high affinity binding site in both untreated and TPA-treated cells with a similar Kd value (0.3 +/- 0.2 nmol/L and 0.4 +/- 0.1 nmol/L, respectively). In untreated cells, IGF-I binding capacity (1.43 +/- 0.41 fmol/10(6) cells) was significantly (p < 0.05) lower than in TPA-treated cells (2.62 +/- 0.87 fmol/10(6) cells). Competition analyses and crosslinking studies revealed the presence of type I IGF receptor both in untreated and TPA-treated cells. Northern analysis demonstrated that mRNA for IGF-I receptor was expressed by both untreated and TPA-treated FLG 29.1 cells. In addition, FLG 29.1 cells released in the conditioned medium IGFBP-2 and IGFBP-4, whose expression was increased by TPA treatment as demonstrated by ligand and immunoblot analyses. The previous observations of chemotactic action of IGF-I on FLG 29.1 cells was confirmed by ultrastructural observations. Indeed, these cells revealed a marked migratory activity in response to nanomolar concentrations of IGF-I. In addition, the IGF-I receptor alpha IR-3 antiserum inhibited the IGF-I-induced FLG 29.1 cell's migratory activity. These findings clearly show that type IIGF receptor is expressed by osteoclast precursors and that IGF-I induces migration of these through the binding to type I IGF receptors. Binding proteins expressed by osteoclast precursors may play an autocrine role in modulating the IGF-I bioeffects.

[Myocardial lipofuscinosis of unknown etiology in a young asymptomatic woman]

An asymptomatic 32-year-old woman was examined because of a family history of unexplained sudden deaths and a left ventricular strain pattern of the ECG during a routine examination. No abnormal finding of the cardiovascular system was present but an endomyocardial biopsy showed focal interstitial fibrosis, myocyte hypertrophy with heavy perinuclear accumulation of lipofuscin. The cause of these abnormalities remains unknown.

Evidence for bioeffects of LY 139478 on the human pre-osteoclastic cell line FLG 29.1

LY 139478, the hydrochloride salt of LY 117018, is a member of the nonsteroidal antiestrogens, benzothiophene derivatives, described to be full estrogen agonists in bone acting via an estrogen receptor-mediated mechanism. However, the cellular actions of these compounds on bone remodelling need to be established. To investigate the "in vitro" properties of LY 139478 on osteoclast precursors, the human pre-osteoclastic cell line FLG 29.1 was examined for evidence of bioeffects of this compound. Binding studies with tritiated 17 beta-estradiol (17 beta E2) demonstrated that the relative potency of LY 139478 in inhibiting estrogen binding to its receptor was equal to that of 17 beta E2. Significant (p < 0.05) dose-dependent inhibition of cell growth was induced by LY 139478 at 10 nM, 100 nM and 1 microM. Calcitonin-induced cAMP accumulation was significantly increased by low (1 pM) and high (1 microM) doses of both 17 beta E2 and the compound with a dose-dependent response. Differently than estrogen, LY 139478 at high dose significantly reduced IL-6 release by these cells. In addition, pharmacological doses of both 17 beta E2 and LY 139478 activated apoptotic cell death. These findings show that the benzothiophene-derived LY 139478 acts directly on the human pre-osteoclastic cell line FLG 29.1 as an estrogen agonist.

Functional estrogen receptors in a human preosteoclastic cell line

The primary biological effect of the estrogen estradiol-17 beta (17 beta E2) on bone is to decrease bone resorption. However, whether 17 beta E2 affects osteoclast differentiation or function directly or through its action on osteoblasts is unclear. To investigate this question we examined the human preosteoclastic cell line FLG 29.1 for evidence of functional estrogen receptors (ERs). Southern blotting of reverse transcription-PCR amplification products with a 32P-labeled cDNA probe for the human ER mRNA demonstrated that FLG 29.1 cells express ER mRNA. Binding of [3H]17 beta E2 to nuclear ERs was steroid specific with approximately 400 saturable, high affinity (Kd approximately 1 nM) binding sites per cell nucleus. Nuclear ERs covalently labeled with [3H]tamoxifen aziridine showed an apparent molecular weight of 65,000 by SDS/PAGE and Western blotting with the D75 monoclonal antibody to human ER. Pretreatment of cells with 0.1, 1.0, or 10 nM 17 beta E2 induced a dose- and time-dependent specific binding of progesterone to FGL 29.1 cells, and stimulation of the cells with 10 nM and 100 nM 17 beta E2 significantly (P < 0.05) reduced cell proliferation. Transcriptional activity of the ER gene was detected by transient transfection of cells with the pERE-BLCAT plasmid containing the estrogen response element for the vitellogenin A2 gene and the bacterial chloramphenicol acetyltransferase reporter gene. Treatment of FLG 29.1 cells with 10 nM 17 beta E2 increased chloroamphenicol acetyltransferase expression from 5- to 29-fold compared to controls. These observations suggest a potential role for estrogen in osteoclastogenesis.

Interactions between ipriflavone and the estrogen receptor

Estrogen replacement therapy is effective in the prevention of postmenopausal osteoporosis, and a direct action of 17-beta-estradiol (17 beta E2) on osteoblastic and osteoclastic cells has been demonstrated. The inhibition of bone resorption by ipriflavone (IP), an isoflavone derivative devoid of estrogenic properties but active in potentiating the effects of estrogen on bone tissue, has been shown in in vitro and in vivo studies and confirmed by clinical data. To investigate the molecular mechanisms that underlie IP effect, we studied the possible interactions of IP and its four main in vivo metabolites (I, II, III, and V) with the estrogen receptor (ER) in the human preosteoclastic cell line FLG 29.1, whose growth and function are modulated by the compound. In parallel experiments, the human breast cancer cell line MCF7 was also analyzed. IP binding sites were demonstrated in the nuclear fraction of FLG 29.1 cells. 17 beta E2 and other steroid compounds failed to displace IP binding to intact FLG 29.1 cells. Similarly, IP and metabolites I, III, and V were not able to displace 17 beta E2 binding to intact MCF7 cells, whereas metabolite II showed an IC50 of 61 nM. 17 beta E2 binding to FLG 29.1 cells was increased after preincubation with metabolites I, III, and V. IP and its metabolites did not induce ER-dependent gene expression in FLG 29.1 and MCF7 cells transfected with a reporter gene and an estrogen response element (ERE).(ABSTRACT TRUNCATED AT 250 WORDS)

Role for autocrine TGF-beta 1 in regulating differentiation of a human leukemic cell line toward osteoclast-like cells

Increasing evidence suggests that transforming growth factor-beta (TGF-beta) is involved in bone formation during remodeling. Using a recently cloned human leukemic cell line (FLG 29.1 cells) we demonstrate that these cells synthesize and secrete TGF-beta 1 and that exogenous or autocrine TGF-beta 1 can induce the same features of osteoclastic-like cells, exerting its effects through the binding to TGF-beta specific receptors. Scatchard analysis of 125I-labeled TGF-beta 1 to FLG 29.1 cells revealed the presence of a single high affinity binding site with a Kd value of approximately 25 pM and a binding capacity of approximately 900 sites/cell. Affinity labeling experiments showed that FLG 29.1 cells express type I and type II TGF-beta receptors. Stimulation of FLG 29.1 cells with low TGF-beta 1 doses reduced cell proliferation and increased cell adhesion and tartrate resistant acid phosphatase (TRAcP) activity. Pretreatment of FLG 29.1 cells with TGF-beta 1 caused a significant and dose-dependent response to calcitonin. Northern blot of total mRNA and analysis of the conditioned media (CM) showed that TGF-beta 1 was synthesized by FLG 29.1 cells. TPA treatment, which induces partial differentiation of these cells, markedly increased TGF-beta 1 mRNA expression and growth factor release. The majority of TGF-beta 1 secreted by TPA-treated cells was in its latent form. However, anti-TGF-beta antibodies inhibited TGF-beta 1 and TPA-induced growth inhibition, calcitonin responsiveness, and TRAcP activity, suggesting that the TPA effect is mediated in part by autocrine TGF-beta 1 and indicating that the cells can activate and respond to the TGF-beta that they secrete. These findings support a potential autocrine role for TGF-beta 1 in osteoclast differentiation.