Improved nuclear magnetic resonance microscopic visualization of joint cartilage using liposome entrapped contrast agents

RATIONALE AND OBJECTIVES

After intraarticular application of gadolinium (Gd)-DTPA the visualization cartilage surface roughness is limited because of diffusion into the cartilage. To improve the sensitivity of magnetic resonance (MR) arthrography to diagnose cartilage surface abnormalities, the authors have tested liposome-entrapped contrast agents.

METHODS

Using paramagnetic contrast agents (Gd-DTPA and manganese chloride) free and entrapped in liposomes, respectively, high resolution MR imaging investigations were performed at 7.1 tesla on intact pig temporomandibular and rabbit knee joints.

RESULTS

After intraarticular injection of the liposome-entrapped contrast agents an excellent contrast between cartilage surface and joint space was achieved. Diffusion of the contrast agent into the cartilage layer was prevented and the visualization of the cartilage surface was improved markedly. Small mechanically and enzymatically induced cartilage lesions could be assessed reliably.

CONCLUSIONS

Intraarticular injection of liposome-entrapped contrast agents can improve the potential of MR arthrography concerning the detection of early osteoarthritic cartilage changes.

Suppression of fibroblast growth factor receptor signaling inhibits pancreatic cancer growth in vitro and in vivo

BACKGROUND & AIMS

Fibroblast growth factors (FGFs) are mitogenic polypeptides that activate specific cell surface FGF receptors (FGFRs). Pancreatic cancers overexpress basic FGF (bFGF) and the type I FGF receptor (FGFR-1), and overexpression of bFGF has been correlated with decreased patient survival. The aim of this study was to examine the effects of abrogation of FGFR-1-dependent signaling on pancreatic cancer cell growth.

METHODS

PANC-1 human pancreatic cancer cells were transfected with a truncated FGFR-1 complementary DNA (FGFR405), resulting in the expression of a kinase-deficient receptor. Activation of endogenous FGFR-1 was assessed in immunoblot studies with antiphosphotyrosine and anti-active mitogen-activated protein (MAP) kinase antibodies. Effects on cell growth were determined in vitro and in nude mice.

RESULTS

PANC-1 clones expressing the truncated receptor showed attenuated receptor tyrosine phosphorylation and MAP kinase activation in response to bFGF, decreased basal cell growth, and a marked decrease in tumor-forming potential in vivo. Confirmatory experiments with MIA PaCa-2 pancreatic cancer cells indicated that FGFR405 also attenuated FGF-dependent MAP kinase activation in this cell line.

CONCLUSIONS

The findings suggest that FGFR-dependent signaling is crucial for pancreatic cancer growth and raise the possibility that inhibition of FGFR signaling may ultimately prove useful as a therapeutic option in patients with pancreatic cancer.

Root surface characteristics of primary teeth from children with prepubertal periodontitis

This study describes the histologic characteristics of root surfaces of primary teeth from children with prepubertal periodontitis (PP). Fifteen primary teeth from 4 children with PP, and 2 control primary teeth from 2 healthy children were examined. Light microscopy revealed normal root surfaces in the control teeth. In contrast, the PP specimens revealed bacteria inside dentin tubules or covering cementum, a cuticle, or resorbed dentin; normal, wider than normal, or hypoplastic cementum; resorption lacunae with various depths; aplastic root resorption; alternate resorption and repair; and active repair. No cementoclasts were found in the resorption lacunae. Scanning electron microscopy revealed intrabony and suprabony root areas, and a "plaque free zone" (PFZ). Colonies of filaments were evident at the cemento-enamel junction (CEJ). The suprabony root surfaces had resorption lacunae, isolated short rods, calculus, colonies of filaments, or colonies composed by an heterogeneous bacterial population. The coronal boundary of the PFZ was the border of a sheet-like structure, which included isolated rods or filaments. At the PFZ, isolated filaments and rods, and a fibril matrix were evident. The apical boundary of the PFZ consisted of bundles of soft tissue remnants or the insertion of the periodontal fibers. The intrabony surfaces were mostly covered by soft tissue, which included isolated filaments and short rods. Resorption lacunae with or without soft tissue were also evident in this area. Crystals of calcium oxalate dihydrate and erythrocytes in distinct forms were found at various root areas. The present findings are different from those previously reported for hypophosphatasia specimens.

MR-microscopic visualization of anisotropic internal cartilage structures using the magic angle technique

NMR microscopic studies of articular cartilage at 7.1 T are presented. Using a special experimental design, T2-weighted spin-echo images of cartilage-bone plugs were taken under variable angles with respect to the static magnetic field B0 to visualize the angular-dependent representation of internal matrix structures mediated by the collagen network arrangement. To quantify the observed orientational effect in the MR images, exact measurements of the transverse relaxation time T2 were taken using the CPMG sequence. The NMR experiments show the strong influence of the cartilage orientation with respect to the static magnetic field on the inhomogeneous appearance of the articular cartilage in the MR image. Additionally performed polarization light microscopic investigations demonstrate the direct relation between the oriented collagenous structures and the anisotropic regions observed in the MR images. A simple cartilage matrix model derived from the experimental findings is proposed, and consequences for the clinical assessment of the articular joint are discussed.

In situ detection of a virulence factor mRNA and 16S rRNA in Listeria monocytogenes

Simultaneous in situ analysis of the structure and function of bacterial cells present within complex communities is a key for improving our understanding of microbial ecology. A protocol for the in situ identification of Listeria spp. using fluorescently tagged, rRNA-targeted oligonucleotide probes was developed. Ethanol fixation and enzymatic pretreatment with lysozyme and proteinase K were used to optimize whole cell hybridization of exponential phase and stationary phase Listeria spp. cells. In parallel, transcript probes carrying multiple digoxigenin molecules were combined with anti-digoxigenin Fab antibody fragments labeled with horseradish peroxidase to detect, via the catalytic deposition of fluorescein-tyramide, the iap-mRNA in single Listeria monocytogenes cells. The iap gene encodes the associated virulence factor p60. Application of the new signal amplification technique resulted in strong signals comparable in intensity to those obtained with fluorescently labeled rRNA-targeted oligonucleotide probes.

Heavy metal ion induction of adhesion molecules and cytokines in human endothelial cells: the role of NF-kappaB, I kappaB-alpha and AP-1

We analyzed the influence of heavy-metal ions on human umbilical vein endothelial cells (HUVEC) in comparison to proinflammatory cytokines (TNF-alpha, IL-1beta) and lipopolysaccharide (LPS). Adhesion molecule and cytokine expressions are upregulated by heavy-metal exposure. Expression of E-selectin on the cell surface was strongly induced by 1-mM concentrations of NiCl2 and CoCl2, whereas ZnCl2 and CrCl3 had no influence. Furthermore, it is shown that NiCl2 induces mRNA expression of E-selectin, intercellular adhesion molecule-1, IL-6 and IL-8 in a 1-mM concentration. The transcription factor NF-kappaB is known to be involved in the regulation of adhesion molecule expression in endothelial cells after activation by proinflammatory cytokines. We demonstrated that treatment of HUVEC with Ni2+ and Co2+ ions induces the translocation of NF-kappaB p65 and also p50 into the nucleus. NF-kappaB binding activity is enhanced under the influence of heavy metals as determined by mobility shift analysis. P65 and p50 are components of the NF-kappaB complexes as confirmed by supershift analysis. We could show that activation at the protein level is accompanied by induction of NF-kappaB p65 mRNA expression. HUVEC also express the NF-kappaB inhibitor I kappaB-alpha (MAD-3). In the early phase of activation by Ni2+ and Co2+ ions, disappearance of I kappaB-alpha in the cytoplasm accompanied p65 translocation, followed by its gradual reappearence. Because I kappaB mRNA could be upregulated by NiCl2 as well as by a mixture of cytokines, we suggest that the replenishment of the inhibitor in the cytoplasm is caused by de novo I kappaB gene expression. In addition to the enhanced DNA-binding activity of NF-kappaB, another transcription factor, AP-1, was also augmented in HUVEC stimulated by NiCl2, CoCl2 or by proinflammatory mediators and the phorbol ester PMA. Fos protein is shown to be a component of the activated AP-1 complex, as determined by supershift analysis, suggesting that it consists of Jun/Fos heterodimers.

Pharmacokinetic and pharmacodynamic evaluation of fluticasone propionate after inhaled administration

OBJECTIVE

To evaluate the pharmacokinetic and systemic pharmacodynamic properties of inhaled fluticasone propionate (FP).

METHODS

Single doses of 0.25, 0.5, 1.0 and 3.0 mg FP were administered to groups of six healthy subjects. Serum concentration profiles of FP were monitored over 24 h by means of high-performance liquid chromatography/mass spectrometry (HPLC/MS-MS). Systemic pharmacodynamic effects were evaluated by measuring endogenous serum cortisol and circulating white blood cells, and analyzed with previously developed integrated pharmacokinetic/pharmacodynamic (PK/PD) models.

RESULTS

FP showed a dose-independent terminal half-life with a mean (SD) of 6.0 (0.7) h. Maximum serum concentrations occurred 1.0 (0.5) h after administration, ranging from 90 pg.ml(-1) for the 0.25 mg dose to 400 pg.ml(-1) for the 3.0 mg dose. This, together with an estimated mean absorption time of nearly 5 h and a known oral bioavailability of less than 1%, indicates prolonged residence at and slow absorption from the lungs. In the investigated dose range, the cumulative systemic effect was dose-dependent for both markers of pharmacodynamic activity. For doses of 0.25, 0.50, 1.0 and 3.0 mg FP, the PK/PD-based cumulative systemic-effect parameters were 159, 186, 257 and 372% .h for lymphocyte suppression, 107, 186, 202 and 348% .h for granulocyte induction and 23.6%, 33.8%, 51.0% and 73.6% for cortisol reduction, respectively. The time courses of lymphocytes, granulocytes and endogenous cortisol could be sufficiently characterized with the applied PK/PD models. The measured in vivo EC50 values, 30 pg.ml(-1) and 7.3 pg.ml(-1) for white blood cells and cortisol, respectively, were in good agreement with predictions based on the in vitro relative receptor affinity of FP.

CONCLUSION

After inhalation, FP follows linear pharmacokinetics and exhibits dose-dependent systemic pharmacodynamic effects that can be described by PK/PD modeling.

[Bilateral ischemic optic neuropathy secondary to acute ergotism]

We report a case of a 31 year-old man who presented a bilateral ischemic optic neuropathy associated with headaches and severe systemic hypertension. This episode appeared after administration of ergotamine tartrate and macrolides. This medication probably led to a vasospasm which occurs in patients with hypertension. The cardiovascular and serum lipid evaluations were normal. A migraine optic neuropathy can be evoked.

Coding of time-varying hormonal signals in intracellular calcium spike trains

In a variety of cell types extracellular hormonal stimuli varying in time are transfered across the cell membrane into repetitive spikes of the intracellular calcium concentration ([Ca2+]i). Distinct temporal patterns of [Ca2+]i spikes are capable of regulating the function and structure of target cells. Here, we investigate the ability of transmembrane signaling to encode time-varying hormonal stimulations (bandlimited Gaussian white noise) in a model of receptor-controlled [Ca2+]i oscillations. The encoding of hormonal signals in [Ca2+]i spike trains is quantified by using an information-theoretic approach allowing to estimate the hormonal stimulus from [Ca2+]i spike trains. Our results suggest that intracellular [Ca2+]i spike trains convey faithful information on temporal variations of extracellular hormonal concentrations at scales of 30-200 sec, corresponding to cut-off frequencies between 5 and 30 mHz of the random hormonal stimulation.

[Pilot study of effectiveness of electrotherapy in the experimental liver metastasis model]

The aim of the present was to assess the effectiveness of low level direct current therapy in liver metastases and the influence of polarity (anode or cathode in the center of the tumor) or current dose (60 or 80 C/cm3). Colorectal metastases were established in 25 BD IX rats by injection of DHD/K12 colon cancer cells under the liver capsule. After 3 weeks the tumors were treated by low level direct current therapy (applied with five platinum electrodes). Histological examination of the removed livers on postoperative day 7 revealed significant destruction of the metastases with localized necroses. The best treatment results were obtained in the group with an anode in the center and a current dose of 80 C/cm3. We conclude that low level direct current therapy may offer an alternative minimal invasive method in the treatment of liver metastases.

[Treatment of fingertip defect injuries with a semi-occlusive dressing]

In the treatment of substance loss of fingertips it is crucial to maintain functional length and to restore adequate sensibility. By treating those injuries with a semiocclusive dressing according to Mennen and Wiese (1993), we were able to achieve both goals with excellent results, avoiding the necessity of local or regional flaps as well as shortening of bone to achieve primary closure. 82 patients with 85 injured digits were treated either conventionally (primary closure with or without shortening of bone, vaseline gauze dressings: 31 digits) or with semiocclusive dressings (54 digits). 42 digits of the latter group with complete protocols were evaluated at the end of treatment. 26 digits with defects of skin and subcutaneous tissue of less than 1 cm2 to more than 2 cm2 necessitated an average of 18 days until complete healing (minimum 6, maximum 46 days). Eight digits with loss of skin, subcutaneous tissues and nailbed healed within 10 to 32 days (average 22 days) and eight digits in which defects included bone loss averaged 49 days for complete healing (37 to 64 days). No complications, especially no infections have been observed. All healed finger-tips were well padded, painless, many without visible scar and with static two-point discrimination between 2 and 8 mm.

A test statistic to detect errors in sib-pair relationships

Several authors have proposed algorithms to detect Mendelian errors in human genetic linkage data. Most currently available methods use likelihood-based methods on multiplex family data to identify typing or pedigree errors. These algorithms cannot be applied in many sib-pair collections, because of lack of parental-genotype information. Nonetheless, misspecifying the relationships between individuals has serious consequences for sib-pair linkage studies: false relationships bias the statistics designed to identify linkage with disease phenotypes. To test the hypothesis that two individuals are sibs, we propose a test statistic based on the summation, over a large number of genetic markers, of the number of alleles shared identical by state by a pair of individuals, for each marker. The test statistic has an approximately normal distribution under the null hypothesis, and extreme negative values correspond to nonsib pairs. Power and significance studies show that the test statistic calculated by use of 50 unlinked markers has 96% power to detect half-sibs and has 100% power to detect unrelated individuals as not full-sib pairs, with a 5% false-positive rate. Furthermore, extreme positive values of the test statistic identify sibs as MZ twins.

Reducing maternal mortality in St Petersburg

Following the entry of St Petersburg into Europe's Healthy Cities Project in 1991 it was decided that the highest priority should be given to reducing the city's maternal mortality ratio, then standing at approximately 70 deaths per 100,000 live births. Preventing deaths from unsafe, illegal abortion became the main focus of attention. The use of modern contraceptive methods was promoted, information was disseminated to improve the utilization of family planning services, special outreach services for teenagers were established, and providers were given opportunities for education and training. The maternal mortality ratio and the abortion rate have now declined and contraceptive use appears to be increasing. These achievements are attributable in large measure to the commitment of a broad spectrum of St Petersburg society as well as to outside support.

Algorithmic complexity of growth hormone release in humans

Most hormones are secreted in an pulsatile rather than in a constant manner. This temporal pattern of pulsatile hormone release plays an important role in the regulation of cellular function and structure. In healthy humans growth hormone (GH) secretion is characterized by distinct pulses whereas patients bearing a GH producing tumor accompanied with excessive secretion (acromegaly) exhibit a highly irregular pattern of GH release. It has been hypothesized that this highly disorderly pattern of GH release in acromegaly arises from random events in the GH-producing tumor under decreased normal control of GH secretion. Using a context-free grammar complexity measure (algorithmic complexity) in conjunction with random surrogate data sets we demonstrate that the temporal pattern of GH release in acromegaly is not significantly different from a variety of stochastic processes. In contrast, normal subjects clearly exhibit deterministic structure in their temporal patterns of GH secretion. Our results support the hypothesis that GH release in acromegaly is due to random events in the GH-producing tumorous cells which might become independent from hypothalamic regulation.

Induction of mitochondrial manganese superoxide dismutase in macrophages by oxidized LDL: its relevance in atherosclerosis of humans and heritable hyperlipidemic rabbits

The objective of the study was to analyze the intracellular antioxidative response of macrophages (Mphi) exposed to increased levels of low density lipoprotein (LDL). We studied manganese superoxide dismutase (MnSOD) and, in part, GSH in cultured human and rabbit Mphi, and in atheromatous arterial tissue of humans and heritable hyperlipidemic (HHL) rabbits. Incubation of human Mphi with oxidized-LDL (ox-LDL) resulted in an induction of MnSOD mRNA production as shown by RT-PCR. MnSOD immunoreactivity (IR) was found to be located in the mitochondria of Mphi. In HHL rabbits, MnSOD activity and GSH concentration were significantly increased in atherosclerotic intima compared to the media of the aorta, but significantly decreased (P<0.01) in larger plaques compared with smaller ones, resulting in a significant inverse correlation of MnSOD activity (r=-0.67, P<0.001) and GSH concentration (r=-0.57, P<0.01) with plaque size. Immunohistology of the atherosclerotic intima revealed MnSOD-IR in Mac-1 (CD 11b/CD 18)-immunoreactive (ir) Mphi of human arteries and, similarly, in RAM-11-ir Mphi of rabbit ones. The relation of MnSOD-ir Mphi decreased with plaque advancement, which is consistent with biochemical findings. Most MnSOD-ir Mphi in atherosclerotic plaques revealed TUNEL-positive nuclei, indicating DNA strand breaks, and p53-IR. We conclude that mitochondrial antioxidants such as MnSOD are induced in Mphi in vitro and in atherosclerotic arteries as a reply to increased mitochondrial oxidation. As normal consequences of an increased oxidative stress due to the exposure to ox-LDL nuclear DNA strand breaks occur, which are suggested to be a signal to increase p53 protein levels. Reactive oxygen species-mediated mitochondrial-dependent pathways are suggested as major contributing pathomechanisms to nuclear damage, which eventually may result in apoptosis. A common response to increased oxidative stress due to modified LDL is presumed in rabbit and human atherosclerotic plaques.