Acute Effect of Selective Chemical Inactivation of Sympathetic or Parasympathetic Atrial Ganglionated Plexus Structures on Atrial Fibrillation Inducibility in Pigs.

We studied the role of both parts of the autonomic intracardiac nervous system in the pathogenesis of atrial fibrillation (AF). In 12 pigs weighing 39±3 kg, AF was induced by burst stimulation. Chemical inactivation of intrinsic cardiac neurons within the right atria was performed by transendocardial injections of liposomal neuromodulators into the dorsal part of the right atrial wall. Sympathetic and parasympathetic terminals were inactivated with 6-hydroxydopamine (6-OHDA, n=6) and ethylcholine aziridinium ion (AF64A, n=6), respectively. Neuromodulators were encapsulated in liposomes (LS) with diameters of 310±50 nm for OHDA and 290±50 nm for AF64A. LS-6-OHDA and LS-AF64A were injected into the ganglionated plexuses after measuring the baseline effective refractory period and assessing myocardial resistance to AF. These measurements were repeated 90 min after the injections. The optimal doses were 0.2 mg/kg for LS-6-OHDA and 0.4 mg/kg for LS-AF64A (in 4 ml of suspension). Immediately after injections of liposomal neuromodulators, almost all pigs showed an increase in HR, and a short-term BP elevation was observed in the LS-AF64A group. At the end of the experiment, similar decrease in the effective refractory period and similar increase in the resistance to AF were observed in all animals. Thus, selective chemical inactivation of cholinergic and adrenergic terminals of the intracardiac nervous system with liposomal neuromodulators increased the resistance to AF in an acute experiment. However, the short observation period does not allow making a definite conclusion about the role of the autonomic nervous system in the pathogenesis of AF, which requires verification of the obtained data in a chronic experiment.

Comparison of dynamic contrast-enhanced MRI parameters of breast lesions at 1.5 and 3.0 T: a pilot study.

OBJECTIVE: To compare dynamic contrast-enhanced (DCE) MRI parameters from scans of breast lesions at 1.5 and 3.0 T. METHODS: 11 patients underwent paired MRI examinations in both Philips 1.5 and 3.0 T systems (Best, Netherlands) using a standard clinical fat-suppressed, T1 weighted DCE-MRI protocol, with 70-76 s temporal resolution. Signal intensity vs time curves were fit with an empirical mathematical model to obtain semi-quantitative measures of uptake and washout rates as well as time-to-peak enhancement (TTP). Maximum percent enhancement and signal enhancement ratio (SER) were also measured for each lesion. Percent differences between parameters measured at the two field strengths were compared. RESULTS: TTP and SER parameters measured at 1.5 and 3.0 T were similar; with mean absolute differences of 19% and 22%, respectively. Maximum percent signal enhancement was significantly higher at 3 T than at 1.5 T (p = 0.006). Qualitative assessment showed that image quality was significantly higher at 3 T (p = 0.005). CONCLUSION: Our results suggest that TTP and SER are more robust to field strength change than other measured kinetic parameters, and therefore measurements of these parameters can be more easily standardized than measurements of other parameters derived from DCE-MRI. Semi-quantitative measures of overall kinetic curve shape showed higher reproducibility than do discrete classification of kinetic curve early and delayed phases in a majority of the cases studied. ADVANCES IN KNOWLEDGE: Qualitative measures of curve shape are not consistent across field strength even when acquisition parameters are standardized. Quantitative measures of overall kinetic curve shape, by contrast, have higher reproducibility.

[THE FIRST CASE OF OCULAR THELAZIASIS IN CROATIA].

The first case of ocular thelaziasis in a human male patient in Croatia is presented. Thelaziasis is a zoonosis caused by nematodes of the genus Thelazia, parasites of the conjunctival bags or tear ducts of mammals and birds. Two types of the genus Thelazia (T.) have been described as causes of infection in humans, T. callipaeda and T. californiensis. To date, less than 300 thelaziasis cases in humans have been reported. This zoonosis is very rare in humans in European countries, with a high incidence in Asian countries, especially in China, Thailand and Japan. Because of the high prevalence of the parasites in the Far East, T. callipaeda is called 'Oriental eye worm'. The first case of thelaziasis in Europe was described in 2008 in Italy and France, where cases in animals had already been reported. Seasonal occurrence of thelaziasis in Europe depends on the presence of the vector, fruit flies of Drosophilidae family, Phortica variegate as the most common type. Adult worm is milky white, females grow to 20 mm and males up to 12 mm. Dogs and cats are the most common sources of infection for humans, which occurs as unilateral ocular infection. The clinical picture of infection is similar to bacterial and allergic conjunctivitis with tearing and foreign body sensation. After removal of worms, clinical signs quickly disappear and there is no need for anthelmintic treatment. In the treatment of secondary infections, local antibiotics and corticosteroids can be applied. The 82-year-old male patient presented to outpatient ophthalmology clinic for occasional sensation of pain, itching, redness and tearing in his left eye during the last few days. His left eye was blind due to previous retinal detachment and had severe conjunctival and ciliary infection with large corneal abscess. Worm-like movement in the lateral canthus was observed. After topical anesthesia, seven worms were removed. Upon surgical extirpation of the parasite, the diagnosis of thelaziasis was verified by microbiological identification. Only two cases of Thelazia in dogs were reported in Croatia, in December 2013 and January 2014. It is important to bear in mind this cause of eye infections, especially when caused by larval stages that are difficult to identify. Untimely diagnosis and inadequate treatment lead to extended illness and complications. The appearance of this parasite in Croatian patients suggests the need for inclusion of the pathogen in the differential diagnosis of bacterial or allergic conjunctivitis.

Characterizing early contrast uptake of ductal carcinoma in situ with high temporal resolution dynamic contrast-enhanced MRI of the breast: a pilot study.

Improvements in the reliable diagnosis of preinvasive ductal carcinoma in situ (DCIS) by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) are needed. In this study, we present a new characterization of early contrast kinetics of DCIS using high temporal resolution (HiT) DCE-MRI and compare it with other breast lesions and normal parenchyma. Forty patients with mammographic calcifications suspicious for DCIS were selected for HiT imaging using T(1)-weighted DCE-MRI with ∼7 s temporal resolution for 90 s post-contrast injection. Pixel-based and whole-lesion kinetic curves were fit to an empirical mathematical model (EMM) and several secondary kinetic parameters derived. Using the EMM parameterized and fitted concentration time curve for subsequent analysis allowed for calculation of kinetic parameters that were less susceptible to fluctuations due to noise. The parameters' initial area under the curve (iAUC) and contrast concentration at 1 min (C(1 min)) provided the highest diagnostic accuracy in the task of distinguishing pathologically proven DCIS from normal tissue. There was a trend for DCIS lesions with solid architectural pattern to exhibit a negative slope at 1 min (i.e. increased washout rate) compared to those with a cribriform pattern (p < 0.04). This pilot study demonstrates the feasibility of quantitative analysis of early contrast kinetics at high temporal resolution and points to the potential for such an analysis to improve the characterization of DCIS.

Quantitative analysis of water proton spectral lineshape: a novel source of contrast in MRI.

Previous work in this laboratory has demonstrated improved anatomic and functional images produced from high spectral and spatial resolution (HiSS) MRI of the water proton signal. The present work tests the hypothesis that different Fourier components of the water resonance represent anatomically and/or physiologically distinct populations of water molecules within each small image voxel. HiSS datasets were acquired from tomatoes and rodent tumors at 4.7 T using echo-planar spectroscopic imaging (spatial and spectral resolutions were 117-150 microm and 1.5-3.1 Hz, respectively). Images of each Fourier component of the water resonance (referred to as Fourier component images, or FCIs) were produced. FCIs at frequencies offset from the peak of the water resonance ('off-peak' FCIs) were compared to images of the Fourier component with largest amplitude, i.e. the water peak-height image. Results demonstrate that off-peak FCIs differ significantly from the water peak-height image and that water resonances are often asymmetric. These results show that water signal at various frequency offsets from the peak of the water resonance come from water molecules in different anatomic/physiologic environments. Off-peak FCIs are a new source of structural and functional information and may have clinical utility.

Connections between response modes in a horizontally driven granular material.

The behavior of a horizontally vibrated quasi-two-dimensional granular system is observed over a wide range of time scales by mapping the velocity fields at the boundary by using high-speed video and decomposing the behavior of the system into the harmonic, subharmonic, and convective responses. The observed relationships between these responses, as well as the fast shearing and the gap that opens between the material and the sidewalls, lead to a refinement of the current convection model, and also reveal that shearing is completely accounted for by the harmonic response. We find that internal degrees of freedom are always significant under horizontal vibration, as the specific boundary conditions (open surface and horizontal driving) give rise to a surface layer whose motion is decoupled by a narrow shear band from that of the bulk. All observed responses are related to this shear band. For example, the specific shape of the shear band gives rise to the surprising presence of period doubling and period quadrupling. As compared to the case of vertical excitation, all the observed responses now arise through new mechanisms.

Convection in a fully immersed granular slurry.

Using vertical vibrations, we have induced convection in a granular system completely immersed in fluid inside a cylindrical container. Convection is established in a single convection roll, which carries the material upward in the center and downward along the side walls of the container. We measure the rise times of tracer particles embedded in the medium at various depths along the central axis of the system. By fitting this data to an appropriate functional form, we obtain information on the depth dependence of convection velocity. Significant differences are found in the frequency and acceleration amplitude dependence of convection between wet and otherwise identical dry systems. In addition, we find that a power-law form provides a better fit to our data than the logarithmic form used in dry systems.

Epidemiological aspects of Balkan endemic nephropathy in a typical focus in Yugoslavia.

Balkan endemic nephropathy is a noninflammatory bilateral kidney lesion that affects rural populations in several circumscribed areas of the Balkans. Its etiology is still not understood, but recently it has been associated with exposure to nephrotoxic mycotoxins. It has been known to be present since the mid-1950s in 14 villages in an endemic area of Croatia, where approximately 10,000 people are at risk. Its prevalence fluctuates between 0.4 and 8.3%, showing a slight decline in recent years, but it has not disappeared from any of the endemic villages. The occurrence of the disease in several ethnic groups contradicts the hypothesis of a primary hereditary basis for Balkan endemic nephropathy. Recently, evidence has been found of an extremely high incidence of urinary tract tumours in the endemic area, and particularly of urothelial tumours of the pelvis and ureter. There may therefore be a common causative agent for these two rare diseases.