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Sensitivity of DNA synthetic phase to near-ultraviolet radiation: chromatid damage at early and late replication periods.

Syrian hamster embryo (SHE) cells were pulse-labeled with bromodeoxyuridine at various periods of the S-phase, and then irradiated with near ultraviolet (NUV) light. Observation of the radiated chromosomes in the subsequent metaphase stage revealed that the period between the second and fourth hour of the S-phase is most sensitive to radiation damage. The prevalent types of chromatid aberrations are 'gaps' and 'breaks'. The results strongly suggest that the detrimental effect of NUV-radiation on chromosomes depends primarily on the particular stage when radiation is applied.

Animals↗

Light therapy for seasonal affective disorder with blue narrow-band light-emitting diodes (LEDs).

BACKGROUND: While light has proven an effective treatment for Seasonal Affective Disorder (SAD), an optimal wavelength combination has not been determined. Short wavelength light (blue) has demonstrated potency as a stimulus for acute melatonin suppression and circadian phase shifting. METHODS: This study tested the efficacy of short wavelength light therapy for SAD. Blue light emitting diode (LED) units produced 468 nm light at 607 microW/cm2 (27 nm half-peak bandwidth); dim red LED units provided 654 nm at 34 microW/cm2 (21 nm half-peak bandwidth). Patients with major depression with a seasonal pattern, a score of > or =20 on the Structured Interview Guide for the Hamilton Depression Rating Scale-SAD version (SIGH-SAD) and normal sleeping patterns (routine bedtimes between 10:00 pm and midnight) received 45 minutes of morning light treatment daily for 3 weeks. Twenty-four patients completed treatment following random assignment of condition (blue vs. red light). The SIGH-SAD was administered weekly. RESULTS: Mixed-effects analyses of covariance determined that the short wavelength light treatment decreased SIGH-SAD scores significantly more than the dimmer red light condition (F = 6.45, p = .019 for average over the post-treatment times). CONCLUSIONS: Narrow bandwidth blue light at 607 microW/cm2 outperforms dimmer red light in reversing symptoms of major depression with a seasonal pattern.

Adult↗

Multispectral classification techniques for terahertz pulsed imaging: an example in histopathology.

Terahertz pulsed imaging is a spectroscopic imaging modality using pulses of electromagnetic radiation (100 GHz-10 THz), and there has been recent interest in studying biomedical specimens. It is usual to display parametric images derived from the measured pulses. In this work, classification was achieved by applying multispectral clustering techniques to sets of parametric images. It was hypothesised that adequate information for clustering was carried in a small number of parametric images, providing these were weighted by complementary physical properties. Materials prepared for histopathological examination were chosen because their condition remained stable during long imaging periods and because their dehydrated state led to greater penetration of the radiation. Two specimens were examined in this pilot study, one of basal cell carcinoma and one of melanoma. Unsupervised ISODATA classification using three selected parametric terahertz pulsed images was compared qualitatively with k-means classification using the shape of the whole time series, and with conventional stained microscope slides. There was good qualitative agreement between the classifications. Classifications were consistent with the morphological appearances expected, but further work is required to determine if tumour discrimination is possible. The results have implications for the future development of the technique as the need for only a small number of features could lead to considerably reduced acquisition times.

Algorithms↗

Nitroglycerin induces migraine headache and central sensitization phenomena in patients with migraine without aura: a study of laser evoked potentials.

In migraineurs nitroglycerin (NTG) induces severe delayed headache, resembling spontaneous migraine attacks. The aim of the present study was to evaluate NTG laser evoked potentials (LEP) features amplitude and pain sensation to laser stimuli during NTG-induced headache. Nine patients were selected. Headache was induced by oral administration of 0.6 mg of NTG; signals were recorded through disk electrodes placed at the vertex and referred to linked earlobes. CO(2)-LEPs delivered by stimulation of the dorsum of both hands and the right and left supraorbital zones were evaluated after the onset of moderate or severe headache resembling spontaneous migraine and at least 72 h after the end of the headache phase. Patients exhibited a significant heat pain threshold reduction and an LEPs amplitude increment during headache when both the supraorbital zones were stimulated. NTG appeared to support a reliable experimental model of migraine, based on the neuronal effects on the integrative-nociceptive structures. The LEPs facilitation during NTG-induced headache may be subtended by a hyperactivity of nociceptive cortex as well as by a failure of pain-inhibitory control.

Adult↗

Evaluation of rat thyroid gland morphophysiological status after three months exposure to 50 Hz electromagnetic field.

Objective of our study was to use morphophysiological criteria in order to determine the sensitivity of male rat thyroid gland to an extremely low frequency electromagnetic field (ELF-EMF) influence and the ability of the gland to repair after period of exposure. Animals were exposed to 50Hz, 50-500 microT ELF-EMF for 3 months when a part of them (group I) were sacrificed, while the rest of animals were subjected to recovery evaluation of the gland and sacrificed after 1 (group II), 2 (group III) and 3 (group IV) weeks. Histological and stereological analyses were performed on paraffin and semifine thyroid gland sections. Serum T3 and T4 were also determined. Histological and stereological analyses showed that the volume density of follicular epithelium and thyroid activation index decreased, while the volume density of colloid and capillary network increased in group I, II and III. The values of all these parameters in group IV were similar to corresponding controls. Serum T3 and T4 concentrations were significantly lower in all exposed animals, except in group I. Results of this study demonstrate that after significant morphophysiological changes caused by ELF-EMF exposure thyroid gland recovered morphologically, but not physiologically, during the investigated repair period.

Animals↗

Clinical experience with the Stretta procedure.

The benchmarks in GERD therapy comprise the commonly prescribed anti-secretory drugs (H2RAs and PPIs) and anti-reflux surgery. Although drugs are typically safe, cost and patient compliance are challenges to long-term management. Furthermore, while heartburn may be controlled with aggressive medical therapy, other symptoms such as regurgitation may persist, reducing patient satisfaction and adversely affecting quality of life. Surgical anti-reflux procedures, most commonly laparoscopic Nissen fundoplication, improve GERD symptoms and normalize esophageal acid exposure in most patients. Patient perception of the potential risk of abdominal surgery and general anesthesia may limit willingness to undergo surgery resulting in only a small portion of GERD sufferers that actually undergo anti-reflux surgery each year. Overall, the Stretta procedure is well tolerated, with an acceptably low incidence of complications and obviates the need for anti-secretory drug therapy for most patients at the 6- and 12-month follow-up. GERD symptom scores, heartburn, satisfaction, and SF-36 scores significantly improve over the baseline and this effect lasts at least 12 months. The symptomatic improvement after Stretta at 12 months in one trial (GERD score, 27 to 9) is similar to that reported by Velanovich after fundoplication (GERD score, 27 to 3). Furthermore, the significant reduction in median esophageal acid exposure time (distal 10.6% to 6.2%, proximal 1.9% to 0.9%), provides objective evidence of an anti-reflux effect. Although the reported studies have been non-randomized, the objective improvement observed in esophageal acid exposure and the persistence of GERD symptom score improvement with repeated measure analysis over a course of 12 months make a significant placebo effect unlikely. Stretta is a promising new technology for the treatment of GERD that should be considered for patients who wish to discontinue a lifelong anti-secretory medication regimen or who have incomplete GERD symptom control on drugs, but are not yet accepting anti-reflux surgery.

Catheter Ablation↗

The Stretta procedure: device, technique, and pre-clinical study data.

The initial concept of delivering RF energy to the gastroesophageal junction for the treatment of GERD was based on the well-established safety profile and scientific clinical evidence supporting the effectiveness of this technology in other disease states. As described in this article, the Stretta procedure is an endoluminal procedure inducing collagen tissue contraction, remodeling, and modulation of the triggering threshold for transient LES relaxations. The preclinical experience with this device included feasibility studies to determine optimal treatment parameters and device design. This was followed by longitudinal animal studies to elucidate the mechanism of safety and effect of this intervention as it relates to LES physiology and histopathology. In these studies, RF elevated the LES pressure and gastric yield pressure in a porcine model of botulinum toxin induced LES hypotension. The elevation in GYP more than 6 months was confirmed in a subsequent evaluation. Thickening of the LES after RF delivery has been demonstrated using histopathological evaluation and EUS. Additionally, using a canine model of triggered transient LES relaxations (tLESR), RF significantly reduced the frequency of tLESRs and reflux events. Additional evaluation was performed in human subjects undergoing esophagectomy, confirming feasibility and Histopathologic results of the treatment. Subsequent clinical trials confirm the safety and mechanism of action data of these pre-clinical studies and are presented in this publication.

Animals↗

Exposure of Escherichia coli to intestinal myoelectrical activity-related electric field induces resistance against subsequent UV(254 nm) (UVC) irradiation.

Survival of Escherichia coli K-12 AB1157 irradiated with UVC (UV(254 nm)) was enhanced after pre-treatment with a low-tension electric field (EF). The EF used was identical to the electrical field generated by the small intestine (myoelectrical migrating complex--MMC), registered in a healthy calf and transmitted into the memory of an EF generator. The EF emitted by the generator was transmitted via electrodes placed in shaken bacterial cultures. The protective effects of the EF on the E. coli survival after exposure to UV were: (i) observed only for the dnaJ(+)dnaK(+) strain, and not for the DeltadnaJdnaK heat shock mutant; (ii) strictly dependent on the temperature at which the bacteria were grown; (iii) most obvious when the bacteria were incubated at 37 degrees C. Moreover, the MMC-related EF and a higher temperature (40 degrees C) show a similar protective effect against UV-irradiation. The results point to the involvement of the heat shock response in the low-tension EF-induced protection of bacterial cells against UVC-irradiation. Additionally, treatment with the MMC-related EF affects total protein contents and their pattern in E. coli cells. The EF-treatment did not show any influence on the level of the argE3(ochre) --> Arg(+) reversions.

Animals↗

A double-dissociation of English past-tense production revealed by event-related potentials and low-resolution electromagnetic tomography (LORETA).

OBJECTIVES: Evidence of systematic double-dissociations of neural activity associated with the generation of regular and irregular past tense in healthy individuals may prove decisive in distinguishing between single- and dual-route models of morphological processing, because the former (connectionist models of morphological processing) have only been able to simulate double-dissociations of past-tense morphology as low-probability phenomena. METHODS: Twenty-eight channel event-related potentials (ERPs) were recorded in response to past-tense production and subsequently analyzed using a 3-stage strategy. RESULTS: A data-driven algorithm temporally segmented the ERPs into 16 distinct epochs of stable field configuration (microstates). A space-oriented brain electric field analysis determined that one of those epochs, 288-321 ms after the verb stem presentation, showed significant differences between the regular and irregular verb conditions. As a further test of these results, a novel source localization technique that computes 3-dimensional distribution of cortical current density in the Talairach brain atlas--low-resolution electromagnetic tomography--found in the above microstate more activity for regulars in the right prefrontal and right temporal areas and for irregulars in the left temporal areas and the anterior cingulate cortex, which can be taken as evidence of systematic double-dissociation. CONCLUSIONS: The present results achieved with a source localization technique provide evidence of a two-way compartmentalization of neural activity corresponding to regular and irregular past tense, thus corroborating the dual-mechanism character of verb morphology.

Adult↗

[Electromagnetic fields in hospitals: wireless-LAN as a risk factor?].

The actual level of exposure to non-ionizing radiation in Swiss hospitals is not well known. Therefore, the electromagnetic field of wireless LAN (WLAN) and other non-ionizing radiation sources in the publicly funded Hospital Thun (Switzerland), where WLAN supports bedside access to the computerized patient record for more than three years, has been measured. The results are compared to the international and national exposure limits for the general public. Nurse workplaces as well as patient rooms show exposure levels well below the legal (national and international) exposure limits. In the investigated patients' room the electromagnetic field of GSM and broadband cellular phone networks are dominant, whereas at the nurse workplace WLAN exposure is the most important source of exposure. The results of a questionnaire survey emphasize, that the hospital staff does not worry much about electromagnetic fields of new ICT technologies.

Attitude of Health Personnel↗