Modulation of class III peroxidase pathways and phenylpropanoids in Arundo donax under salt and phosphorus stress

Arundo donax L. is an invasive species that has been recently employed for biomass production due to its well-known ability to colonize harsh environment. Based on previous observations, the present study investigated the potential role of phenylpropanoids and class III peroxidases to confer adaptation through biochemical and transcriptomic analysis in A. donax after Na⁺ and P excess supply, both in single stress and in combination, and after growth at low P level. The levels of hydrogen peroxide, flavonoids (i.e., quercetin, apigenin and kaempferol derivatives) and the activity of class III peroxidases, as well as the expression of several genes encoding for their enzymes involved in their biosynthesis, increased when Na⁺ was supplied in combination with P. These results suggest that those biomolecules are involved in the response of A. donax, to the presence of +Na and P in the soil. Moreover, even though at the sampling time no significant accumulation of lignin has been determined, the trend of accumulation of such metabolite and most of all the increase of several transcripts involved in its synthesis was found. This work for the first time indicates the need for further investigation devoted to elucidating whether the strengthening of cell walls via lignin synthesis is one of the mechanisms used by A. donax to adapt to harsh environments.

Longitudinal and Cross-Sectional Sampling of Serpentovirus (Nidovirus) Infection in Captive Snakes Reveals High Prevalence, Persistent Infection, and Increased Mortality in Pythons and Divergent Serpentovirus Infection in Boas and Colubrids

The aim of this study of serpentovirus infection in captive snakes was to assess the susceptibility of different types of snakes to infection and disease, to survey viral genetic diversity, and to evaluate management practices that may limit infection and disease. Antemortem oral swabs were collected from 639 snakes from 12 US collections, including 62 species, 28 genera, and 6 families: Pythonidae (N = 414 snakes; pythons were overrepresented in the sample population), Boidae (79), Colubridae (116), Lamprophiidae (4), Elapidae (12), and Viperidae (14). Infection was more common in pythons (38%; 95% CI: 33.1-42.4%), and in boas (10%; 95% CI: 5.2-18.7%) than in colubrids (0.9%, 95% CI: <0.01-4.7%); infection was not detected in other snake families (lamprophiids 0/4, 95% CI: 0-49%; elapids 0/12, 95% CI: 0-24.2%; and vipers 0/14, 95% CI: 0-21.5%), but more of these snakes need to be tested to confirm these findings. Clinical signs of respiratory disease were common in infected pythons (85 of 144). Respiratory signs were only observed in 1 of 8 infected boas and were absent in the single infected colubrid. Divergent serpentoviruses were detected in pythons, boas, and colubrids, suggesting that different serpentoviruses might vary in their ability to infect snakes of different families. Older snakes were more likely to be infected than younger snakes (p-value < 0.001) but males and females were equally likely to be infected (female prevalence: 23.4%, 95% CI 18.7-28.9%; male prevalence: 23.5%, 95% CI 18-30.1%; p-value = 0.144). Neither age (p-value = 0.32) nor sex (p-value = 0.06) was statistically associated with disease severity. Longitudinal sampling of pythons in a single collection over 28 months revealed serpentovirus infection is persistent, and viral clearance was not observed. In this collection, infection was associated with significantly increased rates of mortality (p-value = 0.001) with death of 75% of infected pythons and no uninfected pythons over this period. Offspring of infected parents were followed: vertical transmission either does not occur or occurs with a much lower efficiency than horizontal transmission. Overall, these findings confirm that serpentoviruses pose a significant threat to the health of captive python populations and can cause infection in boa and colubrid species.

Efficient Non-Invasive Plasmid-DNA Administration into Tibialis Cranialis Muscle of "Little" Mice

BACKGROUND

An alternative treatment for growth hormone deficiency based on hGH-DNA administration, followed by electro gene transfer, was investigated by injecting the plasmid into surgically exposed or non-exposed quadriceps or tibialis muscle of immunodeficient "little" mice.

METHODS

An optimization of electrotransfer conditions via a new combination of high/low voltage pulses is presented. After 3 days, serum hGH was determined and in a 28-day assay, the relative growth parameters were compared.

RESULTS

Both groups exhibited similar results: 5.0 ± 2.2 (SD) and 3.5 ± 0.9 ng hGH/ml (P>0.05; n=7) for the exposed quadriceps and non-exposed tibialis treatments, respectively. The final body weight increases were 16.1% for the quadriceps and 18.9% for the tibialis group. The tail and nose-to-tail length increases were 4.5% and 7.1% for the quadriceps and 4.8 and 4.6% for the tibialis group. The right and left femur length increases, obtained from radiographic measurements, were 16.9% and 12.7% for the quadriceps and 19.4% and 12.3% for the tibialis, respectively. A non-significant difference between exposed quadriceps and non-exposed tibialis treatments (P=0.48) was confirmed via a completely integrated statistical analysis. Circulating mIGF-1 levels were 126 ± 47, 106 ± 93 (P>0.05) and 38 ± 15 ng/ml for the quadriceps, tibialis and saline treatments, respectively.

CONCLUSION

These results show that hGH-DNA administration into non-exposed tibialis muscle followed by the new HV/LV electrotransfer protocol was an equally efficient, less traumatic treatment, much more suitable for pre-clinical testing than administration into exposed quadriceps.

Effects of Subthreshold Shocks on Wavelet Propagation during Atrial Fibrillation in Humans

Objectives: Our objectives are: first to investigate the effects of internal cardioversion energies on the wave fronts propagation in the right atrium immediately after the energy delivery; second, to track the time course of these effects.

Methods: The study is based on a measure of organization of the endoatrial electrograms obtained by a multipolar basket catheter inserted in the right atrium. We estimated the level of organization by computing the percentage of points laying on the signal baseline (i.e., number of occurrences, NO). NO values were computed on two-second long windows. Six non-overlapped windows were selected, one just before and five just after the last unsuccessful shock.

Results: Immediately after the shock most of the patients exhibited an increase in the organization patterns. This increase was more evident in those patients with rather disorganized patterns and higher energy threshold. This effect fades within a few seconds after the shock delivery.

Conclusions: Our data confirm the idea that the electrical shock causes a widespread extinction of electrical wavefronts, which regenerates after the shock. Since an increase of organization may lead to a reduction of energy threshold, a potential application of these findings might consist in the delivery of multiple subthreshold shocks instead of a single one.

Human thyroid-stimulating hormone synthesis in human embryonic kidney cells and related N-glycoprofiling analysis for carbohydrate composition determination

A strain of embryonic human kidney cells (HEK293) was transiently co-transfected with the expression vectors coding for the α- and β-subunits of human thyroid-stimulating hormone (hTSH), and, for the first time, a human cell-derived recombinant hTSH was synthesized and extensively characterized. The purification strategy involving two steps provided an overall yield of 55% and a purity level > 90%. The purified material (hTSH-HEK) was analyzed and compared to a CHO-derived recombinant preparation (hTSH-CHO) and to a pituitary-derived (hTSH-Pit) preparation. The three preparations showed an equivalent purity (> 95%) with a hTSH-HEK molecular mass 2.1% lower than that of hTSH-CHO and 2.7% higher than that of hTSH-Pit. Remarkable differences were found in the carbohydrate moiety, the lowest sialic acid content and highest fucose content being observed in hTSH-HEK. In vivo biological activity was confirmed for the three preparations, the hTSH-HEK bioactivity being 39 and 16% lower than those of hTSH-CHO and hTSH-Pit, respectively. The hTSH-HEK circulatory half-life (t _1/2) was also shorter than those of hTSH-CHO (1.5-fold) and hTSH-Pit (1.2-fold). According to these findings, HEK-293-derived hTSH can be considered to be useful for clinical applications, in view as well of its human origin and particular carbohydrate composition.

Thin layered drawing media probed by THz time-domain spectroscopy

Dry and wet drawing materials were investigated by THz time-domain spectroscopy in transmission mode.

Supercooling and freezing processes in nanoconfined water by time-resolved optical Kerr effect spectroscopy

Using heterodyne-detected optical Kerr effect (HD-OKE) measurements, we investigate the vibrational dynamics and the structural relaxation of water nanoconfined in Vycor porous silica samples (pore size ≃ 4 nm) at different levels of hydration and temperatures. At low levels of hydration corresponding to two complete superficial water layers, no freezing occurs and the water remains mobile at all the investigated temperatures with dynamic features similar, but not equal to, the bulk water. The fully hydrated sample shows the formation of ice at about 248 K. This process does not involve all the contained water; a part of it remains in a supercooled phase. The structural relaxation times measured from the decay of the time-dependent HD-OKE signal shows the temperature dependence largely affected by the hydration level; the low frequency (ν < 500 cm(-1)) vibrational spectra obtained by the Fourier transforms of the HD-OKE signal appear less affected by confinement.

Optical Kerr effect of liquid and supercooled water: the experimental and data analysis perspective

The time-resolved optical Kerr effect spectroscopy (OKE) is a powerful experimental tool enabling accurate investigations of the dynamic phenomena in molecular liquids. We introduced innovative experimental and fitting procedures, that enable a safe deconvolution of sample response function from the instrumental function. This is a critical issue in order to measure the dynamics of liquid water. We report OKE data on water measuring intermolecular vibrations and the structural relaxation processes in an extended temperature range, inclusive of the supercooled states. The unpreceded data quality makes possible a solid comparison with few theoretical models: the multi-mode Brownian oscillator model, the Kubo's discrete random jump model, and the schematic mode-coupling model. All these models produce reasonable good fits of the OKE data of stable liquid water, i.e., over the freezing point. The features of water dynamics in the OKE data becomes unambiguous only at lower temperatures, i.e., for water in the metastable supercooled phase. We found that the schematic mode-coupling model provides the more rigorous and complete model for water dynamics, even if its intrinsic hydrodynamic approach does not give a direct access to the molecular information.

Evidence of two distinct local structures of water from ambient to supercooled conditions

The liquid and supercooled states of water show a series of anomalies whose nature is debated. A key role is attributed to the formation of structural aggregates induced by critical phenomena occurring deep in the supercooled region; the nature of the water anomalies and of the hidden critical processes remains elusive. Here we report a time-resolved optical Kerr effect investigation of the vibrational dynamics and relaxation processes in supercooled bulk water. The experiment measures the water intermolecular vibrations and the structural relaxation process in an extended temperature range, and with unprecedented data quality. A mode-coupling analysis of the experimental data enables to characterize the intermolecular vibrational modes and their interplay with the structural relaxation process. The results bring evidence of the coexistence of two local configurations, which are interpreted as high-density and low-density water forms, with an increasing weight of the latter at low temperatures.

211 REVERSED-PHASE HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY AS A TOOL TO ELUCIDATE THE BIOLOGICAL ACTIVITY OF COMMERCIAL EQUINE CHORIONIC GONADOTROPIN (eCG)

Superovulation in ruminants can be induced with a single injection of equine chorionic gonadotropin (eCG). However, ovarian response is sometimes lower than expected because of, among other factors, the source of eCG used. This study aimed at establishing the physical-chemical profile of commercial eCG, in order to find differences which can be related to their biological activity. Four different commercial eCG products for veterinary use (A, B, C, D) and one eCG chemical reagent from Sigma (St. Louis, MO, USA), here used as reference preparation, were analysed by reversed-phase high-performance liquid chromatography (RP-HPLC) using a C4-Grace Vydac 214 TP 54-column (25 cm × 4.6 mm I.D.), with UV detection at 220 nm. All eCG preparations presented at least three peaks with retention times (tR) of ~27(I), 34(II), and 36(III) minutes, with a peak at tR = 27 min common to A, C, D, and Sigma eCG, whereas preparation B did not present this peak. A bioassay test was carried with all of these preparations. Immature 21- to 25-day-old Wistar female rats received the equivalent to 10 IU of eCG of each one of these preparations. Autopsy was performed 48 h later and ovaries were removed and weighed. The average ovarian weight for preparations A, C, D, and Sigma were ~0.0795 ± 0.0107 g, whereas preparation B was 0.035 ± 0.007 g (P < 0.01). Preparation B was not different from saline (0.034 ± 0.002 g). In order to establish which one of these three peaks presented the highest biological activity, a mass equivalent to 10 IU of eCG from peaks I, II, and III of Sigma and of product A were studied. The average ovarian weight of animals injected with material from peak II and III (~0.0285 ± 0.003 g) were similar to that of the control whereas peak I produced ovarian weights of 0.059 ± 0.007 g and 0.075 ± 0.010 g for Sigma and product A, respectively (P < 0.01). These results suggest that the lack of ovarian response to eCG treatments can be related to differences in the physical-chemical profile of commercial eCG products and that RP-HPLC is a fast and reliable tool for detecting these differences. Supported by FAPESP (Grant 11/13096-0).

An optically coupled system for quantitative monitoring of MRI gradient currents induced into endocardial leads

The time-varying gradient fields generated during Magnetic Resonance Imaging (MRI) procedures have the potential to induce electrical current on implanted endocardial leads. Whether this current can result in undesired cardiac stimulation is unknown. This paper presents an optically coupled system with the potential to quantitatively measure the currents induced by the gradient fields into endocardial leads during MRI procedures. Our system is based on a microcontroller that works as analog-to-digital (A/D) converter and sends the current signal acquired from the lead to an optical high-speed light-emitting-diode transmitter. Plastic fiber guides the light outside the MRI chamber, to a photodiode receiver and then to an acquisition board connected to a PC. The preliminary characterization of the performances of the system is also presented.

Isolation of the pituitary gonadotrophic α-subunit hormone of the giant amazonian fish: pirarucu (Arapaima gigas)

The cDNAs of the α-subunit of the pituitary gonadotrophic hormones (GTHα) of fish of the order Osteoglossiformes or the superorder Osteoglossomorpha have never been sequenced. For a better understanding the phylogenetic diversity and evolution of PGHα in fish and for future biotechnological synthesis of the gonadotrophic hormones (ag-FSH and ag-LH), of Arapaima gigas, one of the largest freshwater fishes of the world, its GTHα cDNA was synthesized by reverse transcriptase and the polymerase chain reaction starting from total pituitary RNA. The ag-GTHα-subunit was found to be encoded by 348 bp, corresponding to a protein of 115 amino acids, with a putative signal peptide of 24 amino acids and a mature peptide of 91 amino acids. Ten cysteine residues, responsible for forming 5 disulfide linkages, 2 putative N-linked glycosylation sites and 3 proline residues, were found to be conserved on the basis of the known sequences of vertebrate gonadotrophic hormones. Phylogenetic analysis, based on the amino acid sequences of 38 GTHα-subunits, revealed the highest identity of A. gigas with members of the Acipenseriformes, Anguilliformes, Siluriformes and Cypriniformes (87.1-89.5 %) and the lowest with Gadiformes and Cyprinodontiformes (55.0 %). The obtained phylogenetic tree agrees with previous analysis of teleostei, since A. gigas, of the order of Osteoglossiformes, appears as the sister group of Clupeocephala, while Elopomorpha forms the most basal group of all other teleosts.

Electromagnetic compatibility of WLAN adapters with life-supporting medical devices

This paper investigates the electromagnetic compatibility of 45 critical care medical devices (infusion pumps, defibrillators, monitors, lung ventilators, anesthesia machines and external pacemakers) with various types of wireless local area network (WLAN, IEEE 802.11 b/g, 2.45 GHz, 100 mW) adapters. Interference is evaluated by performing ad-hoc tests according to the ANSI C63.18 recommended practice. The behavior of the devices during the tests was monitored using patient simulators/device testers specific for each device class. Electromagnetic interference cases were observed in three of 45 devices at a maximum distance of 5 cm. In two cases the interference caused malfunctions that may have clinical consequences for the patient. The authors' findings show that the use of these wireless local area network adapters can be considered reasonably safe, although interference may occur if they are operated at very close distance (<10 cm) to the medical devices.

Lymphocytic prolactin does not contribute to systemic lupus erythematosus hyperprolactinemia

OBJECTIVES

Lymphocytic prolactin (PRL) gene expression is detected in the majority of the immune cells and it is not known if this source contributes to hyperprolactinemia in systemic lupus erythematosus (SLE). We have therefore evaluated lymphocytic PRL secretion and gene expression in SLE and healthy controls.

METHODS

Thirty SLE patients (ACR criteria) and 10 controls were selected for the study. Serum levels of PRL and macroprolactin were detected by immunofluorometric assay and gel filtration chromatography, respectively. The lymphocytic biological activity was determined by Nb2 cells bioassays. Lymphocytic PRL gene expression was evaluated by RT-PCR assay.

RESULTS

The median serum PRL levels of the 30 SLE patients was higher than the control group (9.65 (1.9-38.9) vs. 6.40 (2.4-10.3) ng/mL, p=0.03). A significant difference was detected between median serum PRL levels of active SLE, inactive SLE and controls (10.85 (5-38.9) vs. 7.65 (1.9-15.5) vs. 6.40 (2.4-10.3) ng/mL), p=0.01). The higher frequency of mild hyperprolactinemia was detected among active SLE in comparison with inactive SLE and controls (7 (38.9%) vs. 1 (8.3%) vs. 0 (0%)), with statistical significance (p=0.02). Nb2 cells assay revealed uniformly low levels of lymphocytic PRL in active, inactive and control groups without statistical significance among them (24.2 (8-63) vs. 27 (13.6-82) vs. 29.5 (8-72) ng/mL), p=0.84). Furthermore, median lymphocytic PRL gene expression evaluated by RT-PCR assay was comparable in both active and inactive SLE groups (p=0.12).

CONCLUSIONS

This is the first study to exclude a lymphocytic source of PRL, pointing out a pituitary etiology for hyperprolactinemia in SLE. However, other sources from the immune system cannot be ruled out.

Synthesis, purification and characterization of recombinant glycosylated human prolactin (G-hPRL) secreted by cycloheximide-treated CHO cells

Human prolactin (hPRL) is a 199 aminoacid protein hormone with a wide spectrum of biological activities which is best known for its stimulation of lactation and development of mammary gland. This protein contains only one potential asparagine-linked glycosylation site, which is partially (10-30%) occupied when the protein is synthesized in eukaryotic cells. Although the biological activity of glycosylated hPRL (G-hPRL) has been found to be approximately 4-fold lower than that of hPRL, its physiological function is not yet well defined. In order to better characterize and study this hormone variant, we carried out its laboratory scale purification from conditioned medium of genetically modified CHO cells that had been supplemented with cycloheximide. Addition of cycloheximide increased the absolute concentration of G-hPRL approximately 4-fold and the glycosylated versus non-glycosylated hPRL concentration ratio by approximately 7-fold. G-hPRL purification was carried out via a two-step process based on a cationic exchanger and a size-exclusion HPLC (HPSEC) column. Characterization was carried out by HPSEC, Western blotting, MALDI-TOF-MS and in vitro bioassay based on Nb2 and Ba/F3-LLP cells, the biological activity being of the same order (11-15 IU mg(-1)) in the two assays. Our results show that addition of cycloheximide can be an important strategy for increasing glycosylated protein production, facilitating the purification and characterization of these isoforms.

Electromagnetic interference to infusion pumps. Update2008 from GSM mobile phones

Electromagnetic interference (EMI) to critical care medical devices has been reported by various groups. Previuos study demonstrated that infusion pumps are susceptible of false alarm buzzing and block of infusion, when exposed to various EMI sources. Aim of this paper is to investigate the changes in the risk of EMI from the estimates of our previous 2005 survey and to extend the EMI risk assessment to newer telecommunication products: DECT phones and WiFi terminals. With regards to GSM phones, compare to the results obtained in 2005, we observed a decrease in the rate of failure (from 58% to 30%). From our findings, the use of WiFi and DECT does not pose a real risk to infusion systems.

Efficient isolation of the subunits of recombinant and pituitary glycoprotein hormones

Complete dissociation into subunits was attained by incubating Chinese hamster ovary (CHO)-derived or native human thyrotropin, follitropin and lutropin overnight at 37 degrees C in acetic acid. The alpha-and beta-subunits of the pituitary glycoprotein hormones were rapidly and quantitatively isolated by reversed-phase high-performance liquid chromatography (RP-HPLC). A dissociation efficiency of > 98% was obtained on the basis of mass determinations of the heterodimers and subunits carried out via mass spectrometry. CHO-derived or native subunits were isolated on a C4 column (80-90% total recovery) and characterized comparatively for purity, hydrophobicity, molecular mass and charge distribution by HPLC, mass spectrometry, sodium dodecylsulfate-polyacrylamide gel electrophoresis and isoelectric focusing. Thyrotropin was used as a model for showing that, after subunit reassociation, the in vivo bioactivity of the hormone was completely restored. The method described is mild, practical, flexible, and can be adapted to dissociate microgram amounts of native or recombinant glycoprotein hormones, allowing characterization of each subunit.

Radiofrequency dosimetry in subjects implanted with metallic straight wires: a numerical study

A numerical study to investigate the effects of the exposure to electromagnetic fields (EMF) at 900 and 1800 MHz on biological tissues implanted with thin metallic structures has been carried out, using the finite difference time domain (FDTD) solution technique. The results of the model show that the presence of a metallic wire yields to a significant increase in the local specific energy absorption rate (SAR). The present standards and/or guidelines on safe exposures of humans to EMF does not cover persons with implanted devices and thus the threshold levels to define safe exposure conditions might not apply in presence of high SAR gradients, such as the ones generated by thin metallic implanted objects. However, exposure to EMF fields below the actual safe levels even in presence of thin conductive structures cause rather low temperature rises (1 degrees C).

Analysis of a heterodyne-detected transient-grating experiment on a molecular supercooled liquid. I. Basic formulation of the problem

We present the basic equations necessary to interpret heterodyne-detected transient-grating experiments performed on a supercooled liquid composed of anisotropic molecules. The final expressions are given under a form suitable for their direct application to a test case.

Analysis of a heterodyne-detected transient-grating experiment on a molecular supercooled liquid. II. Application to m-toluidine

This paper reports the first detailed analysis of a transient grating (TG) experiment on a supercooled molecular liquid, m-toluidine, from 330K (1.75Tg) to 190K (1.01Tg) based on the theoretical model presented in Paper I of this series. This method allows one to give a precise description, over a wide dynamical range, of the different physical phenomena giving rise to the signals. Disentangling the isotropic and the anisotropic parts of the TG response, a careful fitting analysis yields detailed information on the rotation-translation coupling function. We also extract the structural relaxation times related to the "longitudinal" viscosity over almost 10 decades in time and the corresponding stretching coefficient. The value of some other parameters and information on their thermal behavior is also reported.

Electromagnetic interference to infusion pumps from GSM mobile phones

Electromagnetic interference (EMI) to critical care medical devices has been reported by various groups. Previuos studies have demonstrated that infusion and syringe pumps are susceptible of false alarm buzzing and block, when exposed to various EMI sources. Whether these events may have clinical relevance is still debated. The risk of EMI depends on several factors such as phone emitted power, distance and carrier frequency. We investigated the EMI on infusion and siringe pumps from GSM phones at various distances and emitted powers. Malfunctions were observed in 4/7 infusion pumps and 1/4 syringe pumps exposed to mobiles at their maximum output, for distances as long as 30 cm. The maximum power not inducing any malfunction even at 0 cm distance was also determined. The selection of a proper maximum power class reduces significantly the risk of EMI. Such a function is already built in the GSM standard and thus represents one of the feasible solutions to the EMI problem in hospitals.

P-Wave Morphology Assessment by a Gaussian Functions-Based Model in Atrial Fibrillation Patients

Aim of this study was to present a P-wave model, based on a linear combination of Gaussian functions, to quantify morphological aspects of P-wave in patients prone to atrial fibrillation (AF). Five-minute ECG recordings were performed in 25 patients with permanent dual chamber pacemakers. Patients were divided into high-risk and low-risk groups, including patients with and without AF episodes in the last 6 mo preceding the study, respectively. ECG signals were acquired using a 32-lead mapping system for high-resolution biopotential measurement (ActiveTwo, Biosemi, The Netherlands, sample frequency 2 kHz, 24-bit resolution). Up to 8 Gaussian models have been computed for each averaged P-wave extracted from every lead. The P-wave morphology was evaluated by extracting seven parameters. Classical time-domain parameters, based on P-wave duration estimation, have been also estimated. We found that the P-wave morphology can be effectively modeled by a linear combination of Gaussian functions. In addition, the combination of time-domain and morphological parameters extracted from the Gaussian function-based model of the P-wave improves the identification of patients having different risks of developing AF.

Temperature and SAR measurement errors in the evaluation of metallic linear structures heating during MRI using fluoroptic probes

The purpose of this work is to evaluate the error associated with temperature and SAR measurements using fluoroptic temperature probes on pacemaker (PM) leads during magnetic resonance imaging (MRI). We performed temperature measurements on pacemaker leads, excited with a 25, 64, and 128 MHz current. The PM lead tip heating was measured with a fluoroptic thermometer (Luxtron, Model 3100, USA). Different contact configurations between the pigmented portion of the temperature probe and the PM lead tip were investigated to find the contact position minimizing the temperature and SAR underestimation. A computer model was used to estimate the error made by fluoroptic probes in temperature and SAR measurement. The transversal contact of the pigmented portion of the temperature probe and the PM lead tip minimizes the underestimation for temperature and SAR. This contact position also has the lowest temperature and SAR error. For other contact positions, the maximum temperature error can be as high as -45%, whereas the maximum SAR error can be as high as -54%. MRI heating evaluations with temperature probes should use a contact position minimizing the maximum error, need to be accompanied by a thorough uncertainty budget and the temperature and SAR errors should be specified.

Heart rate and blood pressure variability in patients implanted with rate-responsive pacemaker

Rate-responsive pacemakers (PMs) aim at having pacing rates as similar to physiological cardiac rhythms as possible. The pacemaker INOS(2+)-CLS (Biotronik, Germany) implements a closed loop strategy (CLS) based on indirect measures of right ventricle contractility using intracardiac impedance signal. The contractility is, in turn, related to the autonomic nervous system control to the heart. Aim of this study was to evaluate the 24h beat-to-beat heart rate and blood pressure profiles in patients implanted with CLS rate adaptive PM. 24h ECG and arterial pressure waveform acquisition were performed by a digital Holter system by the Portapres equipment, respectively. A proper-designed algorithm was developed to classify PM pacing modalities. For each beat we estimated the heart rate (HR), and the systolic and diastolic pressure values (SP, DP). So far, 6 patients have been studied: 4 patients have been analyzed both with and without rate responsive modalities (DDD-R and DDD, respectively); 2 patients have been studied only with rate-responsive modality. Results obtained in 6 patients show that this rate adaptive PM accurately preserve the heart rate and blood pressure variability throughout the 24h. In particular, the rate adaptation of PM based on impedance measurements succeeds in maintaining the spontaneous HR, SP and DP on a beat-to-beat basis.

Physico-chemical and biological characterizations of two human prolactin analogs exhibiting controversial bioactivity, synthesized in Chinese hamster ovary (CHO) cells

The synthesis, purification and characterization of G129R-hPRL and S179D-hPRL, the two better-studied antagonists of human prolactin (hPRL), is described. Both of these have been expressed for the first time, in their authentic form, by a stable CHO cell line, at secretion levels of 7.7 and 4.3 microg/10(6) cells/day, respectively. Previous studies had shown that these hPRL analogs, when produced in bacterial cytoplasm, consistently contained misfolded forms and multimers according to the specific denaturation, refolding and purification conditions. These versions also have an N-terminal extra methionine. An extensive physico-chemical characterization was carried out after a practical two-step purification process and included SDS-PAGE and Western blotting analysis, matrix-assisted laser-desorption ionization time-of-flight mass spectral (MALDI-TOF-MS) analysis, high-performance size-exclusion chromatography (HPSEC) and reversed-phase high-performance liquid chromatography (RP-HPLC). This last technique revealed a considerable difference in hydrophobicity due to a single amino acid substitution, with S179D-hPRL less (t(RR) = 0.85 +/- 0.010) and G129R-hPRL more (t(RR) = 1.10 +/- 0.013) hydrophobic than hPRL, where t(RR) is the relative retention time. The biological characterization was based on further refinement of a sensitive proliferation assay using the pro-B murine cell line (Ba/F3) transfected with the long form hPRL receptor cDNA such that the minimal detectable dose was 0.04 ng of hPRL/mL, the Ba/F3-LLP assay. On the basis of this assay, the relative residual agonistic activity of these two products, determined against a hPRL international standard in four independent assays, was 53 x 10(-3) for S179D-hPRL and 70 x 10(-5) for G129R-hPRL. We believe that the present synthesis and characterization could be extremely helpful for studies of these two proteins, which have been reported to antagonize tumor growth-promoting effects of hPRL in vivo in animal models of breast and prostate cancer.

Evaluation of Electromagnetic Interference of GSM Mobile Phones with Pacemakers Featuring Remote Monitoring Functions

The aim of this study was to evaluate whether global system for mobile communication (GSM) cellular phones can affect the home monitoring (HM) function implemented in last generation pacemakers (PM).

METHODS

We performed in vitro and in vivo tests on the BA03 PM (Biotronik GmbH, Berlin, Germany). In vitro we evaluated whether an improper HM procedure or an altered patient-activated HM function occurred. We used two cellular phone models, with a fixed external or internal antenna, positioned close to both the PM and the mobile phone-like device, during handover, ringing, and talking. All the tests were done with the PM in air, at 900 and 1,800 MHz GSM bands, under worst case conditions. A subset of these tests was repeated in 17 patients: the mobile phones were moved both around the PM implant site and the mobile cell phone-like device, during talking.

RESULTS

In vitro, neither the HM procedure nor PM functioning were corrupted by the GSM communications: all the transmissions were correctly received, with a maximum transmission delay of about 110 seconds. In vivo, the rate of successful transmissions was 93%.

CONCLUSION

Our data show that HM function does not call for specific restrictions on the use of GSM cellular phones.

Morphological analysis of P-wave in patients prone to atrial fibrillation

Aim of this study was to present a P-wave model, based on a linear combination of Gaussian functions, to quantify morphological aspects of Pwave in patients prone to atrial fibrillation. Five minutes ECG recordings were performed in 25 patients with permanent dual chamber pacemakers set at 40/min in order to have spontaneous beats. ECG signals were acquired using a 32-lead mapping system for high-resolution biopotential measurement (ActiveTwo, Biosemi, The Netherlands, sample frequency 2 kHz, 24 bit resolution). Four healthy subjects were also recorded as a control group. Up to 8 Gaussian models have been computed for each averaged P-wave extracted from every lead. The P-wave morphology is then evaluated by the following parameters: best model orders @ degrees of freedom adjusted R-square (AdjRsq) =97.5%; minimum (sigmamin) and maximum (sigmamax) standard deviation of the Gaussians included in the model, number of relative maxima and minima (max+min), and zeroes of the fit. Significant differences in the best model order were obtained between the control group and patients group. Accordingly, the number of relative maxima and minima was higher in the patient group. These parameters might all be markers of the fractionated electrical activity that characterizes paroxysmal AF patients in sinus rhythm.

MRI induced heating of pacemaker leads: effect of temperature probe positioning and pacemaker placement on lead tip heating and local SAR

The radio frequency field used in magnetic resonance imaging (MRI) procedures leads to temperature and local absorption rate (SAR) increase for patients with implanted pacemakers (PM). In this work a methodological approach for temperature and SAR measurements using fluoroptic probes is presented. Experimental measures show how the position of temperature probes affects the temperature and SAR value measured at the lead tip. The transversal contact between the active portion of the probe and the lead tip is the configuration associated with the highest values for temperature and SAR, whereas other configurations may lead to an underestimation close to 11% and 70% for temperature and SAR, respectively. In addition measurements were performed on a human-shaped phantom inside a real MRI system, in order to investigate the effect of the PM placement and of the lead geometry on heating and local SAR.

Effects of subthreshold shocks on wavelet propagation during atrial fibrillation in humans

OBJECTIVES

Our objectives are: first to investigate the effects of internal cardioversion energies on the wave fronts propagation in the right atrium immediately after the energy delivery; second, to track the time course of these effects.

METHODS

The study is based on a measure of organization of the endoatrial electrograms obtained by a multipolar basket catheter inserted in the right atrium. We estimated the level of organization by computing the percentage of points laying on the signal baseline (i.e., number of occurrences, NO). NO values were computed on two-second long windows. Six non-overlapped windows were selected, one just before and five just after the last unsuccessful shock.

RESULTS

Immediately after the shock most of the patients exhibited an increase in the organization patterns. This increase was more evident in those patients with rather disorganized patterns and higher energy threshold. This effect fades within a few seconds after the shock delivery.

CONCLUSIONS

Our data confirm the idea that the electrical shock causes a widespread extinction of electrical wavefronts, which regenerates after the shock. Since an increase of organization may lead to a reduction of energy threshold, a potential application of these findings might consist in the delivery of multiple subthreshold shocks instead of a single one.

Nonlinear Coupling Among Heart Rate, Blood Pressure, and Respiration in Patients Susceptible to Neuromediated Syncope

The aim of this study is to evaluate the degree of coupling between the cardiovascular variability series and the respiration in subjects susceptible to neurally mediated syncope. Twenty-one informed patients susceptible to syncope and ten sex- and age-matched control subjects were enrolled in the study. ECG, respiration activity, and arterial blood pressure were simultaneously recorded at rest (controlled and free breathing) and during the 70 degrees head-up TILT test (free breathing). The degree of nonlinear coupling among heart rate variability (HRV), blood pressure variability (BPV), and respiration was quantified by means of two indices according to a multivariate embedding-based approach. Eleven patients developed syncope during the TILT test. We found that during the late TILT phase, the TILT-positive group experienced a significant increase in nonlinear coupling respect to the mid TILT phase (p < 0.01, Wilcoxon nonparametric test for pair data) while the TILT-negative group did not (p < 0.01, Mann-Whitney U-test). If the proposed nonlinear coupling indexes can be considered expression of the coupling mechanisms involved in the vagal regulation of the cardiovascular system, an increase in vagal tone accompanied by a decrease in sympathetic activity seem to occur before a vasovagal event.

A novel heart/trunk simulator for the study of electromagnetic interference with active implantable devices

This paper describes a portable heart simulator for the study of electromagnetic interference with active implantable devices. The simulator consists of plexiglas box divided into three chambers simulating the left atrium and the ventricles, plus a lateral compartment for the implantable device. The box is linked to a laptop computer by an analogue-to-digital convertor board, and the three chambers are monitored and driven by dedicated hardware and software interfaces. Synthetic endocardial atrial and ventricle signals for 13 cardiac rhythms are stored in the computer. They are applied to the cardiac chambers by AgCl plates. Sensing electrodes are in the form of AgCl needles inserted in saline. The simulator was able to demonstrate the behaviour of three pacemakers tested in the absence and presence of electromagnetic interference, generated by mobile phones (European GSM 900 and 1800 MHz) that emitted up to 2W (1 W at 1800 MHz). Pacemakers can be programmed with sensitivity from 0.1 mV to 5 mV, pulse width from 0.1 ms to 1.5 ms and pulse amplitude from 0.5 V to 5 V. The structural separation in three cardiac chambers (plus the one for the device) allowed a fast analysis procedure for dual- and tri-chamber implantable devices.

On the mechanisms of interference between mobile phones and pacemakers: parasitic demodulation of GSM signal by the sensing amplifier

The aim of this study was to investigate the mechanisms by which the radiated radiofrequency (RF) GSM (global system for mobile communication) signal may affect pacemaker (PM) function. We measured the signal at the output of the sensing amplifier of PMs with various configurations of low-pass filters. We used three versions of the same PM model: one with a block capacitor which short circuits high-frequency signals; one with a ceramic feedthrough capacitor, a hermetically sealed mechanism connecting the internal electronics to the external connection block, and one with both. The PMs had been modified to have an electrical shielded connection to the output of the sensing amplifier. For each PM, the output of the sensing amplifier was monitored under exposure to modulated and non-modulated RF signals, and to GSM signals (900 and 1800 MHz). Non-modulated RF signals did not alter the response of the PM sensing amplifier. Modulated RF signals showed that the block capacitor did not succeed in short circuiting the RF signal, which is somehow demodulated by the PM internal non-linear circuit elements. Such a demodulation phenomenon poses a critical problem because digital cellular phones use extremely low-frequency modulation (as low as 2 Hz). which can be mistaken for normal heartbeat.

Experimental studies of the ortho-toluidine glass transition

The thermodynamic and dynamics proprieties of ortho-toluidine, in the vicinity of a glass transition, have been studied by calorimetric and by two light scattering techniques, depolarized light scattering and time-resolved optical Kerr effect. Differential scanning microcalorimetry clearly detects a glass transition in o-toluidine and it measures some thermodynamics critical parameters, in particular, the transition temperature. The light scattering data have been analyzed according to the mode-coupling theory. This theory gives a good interpretation of our data and it allows to extract safely the critical parameters of the o-toluidine dynamics. We found a fair agreement between the analysis outputs performed in the frequency domain and in the time domain. Finally, we compared the glass transition features of o-toluidine with that of its isomer meta-toluidine, looking for some general idea about the molecular aspects of the glass transition.