Abnormal network connections to early visual cortex in posterior cortical atrophy

INTRODUCTION

Posterior Cortical Atrophy (PCA), a visual variant of Alzheimer's disease, initially manifests with higher-order visual disorders and parieto/temporo-occipital atrophy. Recent studies have shown remote functional impairment in both distant brain networks and along the calcarine sulcus (V1). Functional alteration in the calcarine differs along its length, reflecting center to periphery visual space differences. Herein, we aim to connect between these two sets of findings by looking at the retinotopic patterns of functional connectivity between large-scale brain networks and V1, comparing patients with normally sighted subjects.

METHODS

Resting state functional magnetic resonance imaging (fMRI) and T1 anatomical scans were obtained from 11 PCA patients and 17 age-matched healthy volunteers. Default mode network (DMN) and fronto parietal network (FPN) were defined and differences between the networks in patients and healthy controls were evaluated at the whole brain level, specifically their connectivity to V1.

RESULTS

Connectivity patterns within the DMN and the FPN were similar between the groups, although differences were found in regions within and beyond the networks. Focusing on V1, in the control group we identified the expected pattern of a distributed connectivity along eccentricity, with foveal regions showing stronger connectivity to the FPN and peripheral regions showing stronger connectivity to the DMN. However, in PCA patients we could not identify a clear difference in connectivity along the eccentricities.

CONCLUSION

Lost specialization of function along the calcarine in PCA patients may have further implications on large-scale networks or vice versa. This impairment, distant from the core pathology, might explain patients' visual disabilities.

Brain activation in individuals suffering from bulimia nervosa and control subjects during sweet and sour taste stimuli

Introduction

Episodes of eating great quantities of extremely sweet and often aversive tasting food are a hallmark of bulimia nervosa. This unique eating pattern led researchers to seek and find differences in taste perception between patients and healthy control subjects. However, it is currently not known if these originate from central or peripheral impairment in the taste perception system. In this cross sectional study, we compare brain response to sweet and sour stimuli in 5 bulimic and 8 healthy women using functional magnetic resonance imaging (fMRI).

Materials and methods

Sweet, sour and neutral (colorless and odorless) taste solutions were presented to subjects while undergoing fMRI scanning. Data were analyzed using a block design paradigm.

Results

Between-group differences in brain activation in response to both sweet and sour tastes were found in 11 brain regions, including operculum, anterior cingulate cortex, midbrain, and cerebellum. These are all considered central to perception and processing of taste.

Conclusion

Our data propose that sweet and sour tastes may have reward or aversion eliciting attributes in patients suffering from bulimia nervosa not found in healthy subjects, suggesting that alteration in taste processing may be a core dysfunction in bulimia nervosa (BN).

Global Brain Involvement in Posterior Cortical Atrophy: Multimodal MR Imaging Investigation

Posterior cortical atrophy (PCA), considered a visual variant of Alzheimer's disease, has similar pathological characteristics yet shows a selective visual manifestation with relative preservation of other cortical areas, at least at early stages of disease. Using a gamut of imaging methods, we aim to evaluate the global aspect of this relatively local disease and describe the interplay of the involvement of the different brain components. Ten PCA patients and 14 age-matched controls underwent MRI scans. Cortical thickness was examined to identify areas of cortical thinning. Hippocampal volume was assessed using voxel-based morphometry. The integrity of 20 fiber tracts was assessed by Diffusion Tensor Imaging. Regions of difference in global functional connectivity were identified by resting-state fMRI, using multi-variant pattern analysis. Correlations were examined to evaluate the connection between grey matter atrophy, the network changes and the disease load. The patients presented bilateral cortical thinning, primarily in their brains' posterior segments. Impaired segments of white matter integrity were evident only within three fiber tracts in the left hemisphere. Four areas were identified as different in their global connectivity pattern. The visual network-related areas showed reduced connectivity and was correlated to atrophy. Right Broadman area 39 showed in addition increased connectivity to the frontal areas. Global structural and functional imaging pointed to the highly localized nature of PCA. Functional connectivity followed grey matter atrophy in visual regions. White matter involvement seemed less prominent, however damage is directly related to presence of disease and not mediated only by grey matter damage.

Microelectrode Recordings Validate the Clinical Visualization of Subthalamic-Nucleus Based on 7T Magnetic Resonance Imaging and Machine Learning for Deep Brain Stimulation Surgery

BACKGROUND

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a proven and effective therapy for the management of the motor symptoms of Parkinson's disease (PD). While accurate positioning of the stimulating electrode is critical for success of this therapy, precise identification of the STN based on imaging can be challenging. We developed a method to accurately visualize the STN on a standard clinical magnetic resonance imaging (MRI). The method incorporates a database of 7-Tesla (T) MRIs of PD patients together with machine-learning methods (hereafter 7 T-ML).

OBJECTIVE

To validate the clinical application accuracy of the 7 T-ML method by comparing it with identification of the STN based on intraoperative microelectrode recordings.

METHODS

Sixteen PD patients who underwent microelectrode-recordings guided STN DBS were included in this study (30 implanted leads and electrode trajectories). The length of the STN along the electrode trajectory and the position of its contacts to dorsal, inside, or ventral to the STN were compared using microelectrode-recordings and the 7 T-ML method computed based on the patient's clinical 3T MRI.

RESULTS

All 30 electrode trajectories that intersected the STN based on microelectrode-recordings, also intersected it when visualized with the 7 T-ML method. STN trajectory average length was 6.2 ± 0.7 mm based on microelectrode recordings and 5.8 ± 0.9 mm for the 7 T-ML method. We observed a 93% agreement regarding contact location between the microelectrode-recordings and the 7 T-ML method.

CONCLUSION

The 7 T-ML method is highly consistent with microelectrode-recordings data. This method provides a reliable and accurate patient-specific prediction for targeting the STN.

Early suppression of peripheral mononuclear blood cells in sepsis in response to stimulation with cytomegalovirus, OKT3, and pokeweed mitogen

Critically ill patients are at risk for sepsis, and immunosuppressive mechanisms may prevail. Whether functional tests are helpful to detect immune alterations is largely unknown. Therefore, we tested the hypotheses that reactivity of peripheral blood mononuclear cells (PBMCs) to secrete interferon-γ (IFNγ) following stimulation in vitro is decreased in patients with early sepsis compared with postoperative patients. IFNγ secretion [enzyme-linked immunospot (ELISpot)] in response to stimulation with cytomegalovirus (CMV), pokeweed mitogen (PWM), muromonab-anti-CD3 (OKT3), and human leukocyte antigen (HLA)-DRA-mRNA expression and serum cytokine concentrations were repeatedly [days 1, 3, 5, and 7 after intensive care unit (ICU) admission] determined in patients with sepsis (n = 7) and patients undergoing major abdominal surgery (radical prostatectomy, cystectomy, n = 10). In a second cohort, HLA-DRA expression was assessed in 80 patients with sepsis, 30 postoperative patients, and 44 healthy volunteers (German clinical trials database no. 00007694). In patients with sepsis, IFNγ secretion (ELISpot) was decreased compared with controls after stimulation with CMV (P = 0.01), OKT3 (P = 0.02), and PWM (P = 0.02 on day 5), whereas unstimulated IFNγ secretion did not differ. HLA-DRA expression was also significantly decreased in patients with sepsis at all time points (P = 0.004) compared with postoperative surgical patients, a finding confirmed in the larger cohort. Reactivity of PBMCs to stimulation with CMV, PWM, and OKT3 as well as HLA-DRA expression was already decreased upon ICU admission in patients with sepsis when compared with postoperative controls, suggesting early depression of acquired immunity. ELISpot assays may help to clinically characterize the time course of immunocompetence in patients with sepsis.NEW & NOTEWORTHY We observed suppression of reactivity to stimulation with cytomegalovirus, muromonab-anti-CD3, and pokeweed mitogen in mononuclear blood cells of patients with early sepsis when compared with postoperative controls. Thus, there is early depression of acquired immunity in sepsis. Enzyme-linked immunospot assays may help to characterize immunocompetence in patients with sepsis.

Is It Me or My Hormones? Neuroendocrine Activation Profiles to Visual Food Stimuli Across the Menstrual Cycle

CONTEXT

Homeostatic energy balance is controlled via the hypothalamus, whereas regions controlling reward and cognitive decision-making are critical for hedonic eating. Eating varies across the menstrual cycle peaking at the midluteal phase.

OBJECTIVE

To test responses of females with regular cycles during midfollicular and midluteal phase and of users of monophasic oral contraception pills (OCPs) to visual food cues.

DESIGN

Participants performed a functional magnetic resonance imaging while exposed to visual food cues in four time points: fasting and fed conditions in midfollicular and midluteal phases.

PATIENTS

Twenty females with regular cycles and 12 on monophasic OCP, aged 18 to 35 years.

MAIN OUTCOME MEASURES

Activity in homeostatic (hypothalamus), reward (amygdala, putamen and insula), frontal (anterior cingulate cortex, dorsolateral prefrontal cortex), and visual regions (calcarine and lateral occipital cortex).

SETTING

Tertiary hospital.

RESULTS

In females with regular cycles, brain regions associated with homeostasis but also the reward system, executive frontal areas, and afferent visual areas were activated to a greater degree during the luteal compared with the follicular phase. Within the visual areas, a dual effect of hormonal and prandial state was seen. In females on monophasic OCPs, characterized by a permanently elevated progesterone concentration, activity reminiscent of the luteal phase was found. Androgen, cortisol, testosterone, and insulin levels were significantly correlated with reward and visual region activation.

CONCLUSIONS

Hormonal mechanisms affect the responses of women's homeostatic, emotional, and attentional brain regions to food cues. The relation of these findings to eating behavior throughout the cycle needs further investigation.

A millikelvin all-fiber cavity optomechanical apparatus for merging with ultra-cold atoms in a hybrid quantum system

We describe the construction of an apparatus designed to realize a hybrid quantum system comprised of a cryogenically cooled mechanical oscillator and ultra-cold ⁸⁷Rb atoms coupled via light. The outstanding feature of our instrument is an in situ adjustable asymmetric all-fiber membrane-in-the-middle cavity located inside an ultra-high vacuum dilution refrigerator based cryostat. We show that Bose-Einstein condensates of N=2×10⁶ atoms can be produced in less than 20 s and demonstrate a single photon optomechanical coupling strength of g₀=2π×9 kHz employing a high-stress Si₃N₄ membrane with a mechanical quality factor Q_m>10⁷ at a cavity setup temperature of T_MiM = 480 mK.

The role of mode match in fiber cavities

We study and realize asymmetric fiber-based cavities with optimized mode match to achieve high reflectivity on resonance. This is especially important for mutually coupling two physical systems via light fields, e.g., in quantum hybrid systems. Our detailed theoretical and experimental analysis reveals that on resonance, the interference effect between the directly reflected non-modematched light and the light leaking back out of the cavity can lead to large unexpected losses due to the mode filtering of the incoupling fiber. Strong restrictions for the cavity design result out of this effect and we show that planar-concave cavities are clearly best suited. We validate our analytical model using numerical calculations and demonstrate an experimental realization of an asymmetric fiber Fabry-Pérot cavity with optimized parameters.

Neural Correlates of Morphological Processes in Hebrew

Is morphology a discrete and independent element of lexical structure or does it simply reflect a fine tuning of the system to the statistical correlation that exists among the orthographic and semantic properties of words? Imaging studies in English failed to show unequivocal morphological activation that is distinct from semantic or orthographic activation. Cognitive research in Hebrew has revealed that morphological decomposition is an important component of print processing. In Hebrew, morphological relatedness does not necessarily induce a clear semantic relatedness, thus, Hebrew provides a unique opportunity to investigate the neural substrates of morphological processing. In this functional magnetic resonance imaging study, participants were required to perform judgment tasks of morphological relatedness, semantic relatedness, rhyming, and orthographic similarity. Half of the morphologically related words were semantically related and half were semantically unrelated. This design was chosen to induce explicit morphological processing. We identified two locations involved in morphological processing: the left middle frontal gyrus and the left inferior parietal sulcus. Comparing locations of morphological related activation to the locations of semantic and orthographic related activation, we found that the areas neighbored but only partially overlapped. The similarity in activation between the two morphological conditions eliminates the possibility that morphological activation simply results from the semantic properties of the words. These results demonstrate the important role of morphological processing in reading and suggest that morphological analysis is a distinct process of visual word recognition.

A loss of fecundity in a population of mudsnails Hydrobia ventrosa caused by larval trematodes does not measurably affect host population equilibrium level

Host snail demography and trematode parasitism were followed for one host generation in a shallow brackish lagoon of the western Baltic Sea. In addition, a laboratory experiment was simultaneously conducted to quantify the effects of parasitic infection on host fecundity. Hydrobia ventrosa of the cohort of 1996 had a maximum life-span of up to 2 years and reproduced between May and November of their second calendar year in 1997. Snails died after reproduction. The first trematode infections appeared in May 1997 when the snails started to mature. Total trematode prevalence peaked in summer and declined during winter to the lowest level in early spring 1998. Eight taxa of larval trematodes were found. Egg production of females with trematode infections was significantly reduced. Among females with pre-patent infections, about 20% were still able to produce eggs. Among females with patent infections merely 9% could lay eggs, compared to an average of about 51% in uninfected females. Taking into account a summer prevalence of about 25%, parasitic infections caused an overall reduction in egg production of the snail host population of about 15%. The reduction in host fecundity as a result of larval trematode infection did not measurably affect the population dynamics of H. ventrosa, because other environmental factors, especially winter severity and available food supply, were concluded to be much more relevant.

Optimal performance of an immersed membrane bioreactor equipped with a draft tube for domestic wastewater reclamation

One of the options to prevent membrane fouling is to implement air lifting that can improve the cake removal from the membrane surface. This study presents the results of tests that were carried out at the Institutes for Desert Research, Kiryat Sde-Boker, Israel, and focused on the influence of hydrodynamic conditions on fouling in a pilot-scale immersed membrane bioreactor (IMBR) using a hollow fiber membrane module of ZW-10 (Zenon Environmental, Canada) under ambient conditions. In this system, the cross-flow velocities across the membrane surface were induced by one conical and four cylindrical draft-tubes. The relationship between the crossflow velocity and the aeration intensity, the influence of the crossflow on fouling rate under various hydrodynamic conditions were investigated and optimal operating conditions were obtained. Optimal operating conditions were reached during the long-term experiment period (70 days) for the treatment of domestic wastewater. The system was stable without external chemical cleaning. The results showed that the permeate was of high quality, and the removal of COD and BOD was 94.0% and 98.8%, respectively. The crossflow near the membrane surface reveals a major contribution for minimizing membrane fouling, and could offer guidelines for future design of similar systems.

Immersed membrane bioreactor (IMBR) for treatment of combined domestic and dairy wastewater in an isolated farm

In many regions dairy farms and milk processing industries discharge large quantities of their wastes to the surroundings posing serious environmental risks. This problem is mostly faced in small dairy farms and isolated communities lacking both central collection and conventional wastewater treatment systems. Dairy wastewater is characterized by high concentrations of organic matter, solids, nutrients, as well as fractions of dissolved inorganic pollutants, exceeding those levels considered typical for high strength domestic wastewaters. With the purpose of treating the combined dairy and domestic wastewater from a small dairy farm in the Negev Desert of Israel, the use of a recent emerging technology of Immersed Membrane BioReactor (IMBR) was evaluated over the course of 500 test hours, under a variety of wastewater feed quality conditions (during the test periods, the feed BOD5 ranged from 315 ppm up to 4,170 ppm). The overall performance of a pilot-scale Ultrafiltration (UF) IMBR process for a combined domestic and dairy wastewater was analyzed based on the Data Envelopment Analysis (DEA) method. The IMBR performance in terms of membrane performance (permeate flux, transmembrane pressure, and organic removal) and DEA model (Technical Efficiency) was acceptable. DEA is an empirically based methodology and the research approach has been found to be effective in the depiction and analysis for complex systems, where a large number of mutual interacting variables are involved.

Hybrid membrane systems for secondary effluent polishing for unrestricted reuse for agricultural irrigation

Field experiments are in progress for secondary wastewater upgrading for unrestricted utilization for agricultural irrigation. The integrative approach of secondary effluent polishing is based on using a hybrid UltraFiltration (UF) and Reverse Osmosis (RO) membrane pilot system with a capacity of around 1 m3/hr. The UF effluent is used to feed the RO membranes. The RO permeate is subsequently applied for vegetable irrigation. Field results indicate the importance of the UF component in the removal of the organic matter and the pathogens that are still contained in the secondary effluent. Under specific conditions, when the dissolved solids content is relatively low, regarding sanitary and health aspects, the UF effluent can be applied for unrestricted irrigation. During the RO stage most nutrients are removed, allowing application of the effluent without jeopardizing the soil fertility and the aquifers. Preliminary economic assessment indicates that the extra cost for effluent polishing via the UF stage only is in the range of 5 to 15 US cents/m3. The extra cost for the RO stage is also assessed at 10 to 25 US cents/m3. The additional cost depends to a large extent on the quality of the incoming raw secondary effluent and local requirements of the command region.

Effects of repeated doses of intravenous immunoglobulin in myasthenia gravis

The authors administered repeated courses of intravenous immunoglobulin (IVIg) to nine patients at the onset of an exacerbation of generalized myasthenia gravis (MG). Anticholinesterase medication (nine patients) and corticosteroid dosage (six patients) had been kept constant for a 2-month period. Six patients received two courses, two patients received three courses, and one patient received five courses. Twenty of 23 courses resulted in satisfactory improvement beginning 4.3 +/- 1.2 days after start of IVIg and becoming maximal 8.2 +/- 2.0 days, with sustained improvement lasting 106.6 +/- 49.1 days. Vital capacity increased from an average of 1845.1 +/- 489 cc to 2894 +/- 762 cc (p less than 0.01) at peak effect. Four of nine patients had a decrease in strength before improvement. There was no significant change in acetylcholine receptor antibody titers before or after therapy. Side effects were minimal. Of the three patients who had nonsatisfactory course, two responded well to additional IVIg. IVIg can produce repeated beneficial effects in patients with MG and may be useful as an adjunct in the management of MG.

High-dose intravenous immunoglobulin in the management of myasthenia gravis

Intravenous immunoglobulin, 400 mg/kg, was administered daily for five days to 12 patients with exacerbation of generalized myasthenia gravis. Degree of weakness, duration of illness, use of prednisone, and history of thymectomy or thymoma did not affect the response to intravenous immunoglobulin. Eleven patients improved, beginning 3.6 +/- 2.7 (mean +/- SD) days after the start of treatment and becoming maximal in 8.6 +/- 4.6 days, with sustained improvement lasting 52 +/- 37 days. Vital capacity increased from 1748 +/- 510 to 2700 +/- 614 mL at peak effect. Decreases in strength occurred in four patients beginning on day 3.2 +/- 2.5, lasted 1.5 +/- 0.6 days, and were mild in three patients. Other effects were minimal. There was no significant change in acetylcholine receptor antibody titers, which were elevated in all patients. Immunoglobulin seemed to produce a more rapid improvement than corticosteroids and is recommended as an adjunct in the management of myasthenia gravis exacerbations.

Inhibition of natural killer cell activity by a soluble substance released by rat peritoneal cells

We describe here a soluble substance released by nonadherent cells from the peritoneal cavity of W/Fu rats that markedly inhibits the activity of mouse, rat, and human natural killer (NK) cells. The NK-inhibiting substance (NK-IS) has low molecular weight (less than 1000), is heat resistant (100 degrees for 15 min), and is insensitive to nonspecific proteases. NK-IS is produced in the presence of indomethacin (1 to 10 micrograms/ml), suggesting it is not prostaglandin. The inhibitory effect was seen on unstimulated as well as on cells activated in vivo or in vitro by Corynebacterium parvum. The activity of cells mediated antibody-dependent cell cytotoxicity (K-cells) was also inhibited by NK-IS although to a lesser degree. In sharp contrast, the substance had little effect on lysis mediated by murine or human cytotoxic T-lymphocytes. Production of NK-IS from rat peritoneal cells was significantly greater than by spleen cells. since the peritoneal cavity is relatively deficient in base-line NK activity compared to spleen, these data suggest that NK-IS may play an in vivo role in the expression of NK cytotoxicity.

Augmentation of NK activity by Corynebacterium parvum fractions in vivo and in vitro

Biochemically modified whole cell preparations and derived fractions of Corynebacterium parvum (C. parvum) were evaluated for the ability to augment natural killer cell cytoxicity in vivo and in vitro in rats. Unfractionated C. parvum enhanced peritoneal cell (Pc) NK activity in a dose dependent fashion. This activity appeared to be enriched in insoluble light residue material obtained from hot phenol water extraction. Enhancement of Pc cytotoxicity was significantly greater at all time points tested in rats injected with light residue when compared to rats injected with comparable amounts (by dry weight) of unfractionated organisms. In addition, pyridine extractable material and HCl modified preparations were capable of boosting Pc NK activity following intraperitoneal (I.P.) injection. Periodate treatment abrogated C. parvum's ability to boost Pc cytotoxicity and insoluble residue material obtained from pyridine extraction was likewise devoid of NK-enhancing properties. Culture of rat spleen cells overnight with unfractionated C. parvum, light residue and pyridine residue materials enhanced NK cytotoxicity whereas HCl and periodate modified whole cell preparations as well as phenol and pyridine extractable material were incapable of boosting cytotoxicity in vitro. In vitro augmentation by culturing with light residue was dependent on the presence of adherent cells in rat spleen cell populations. Pyridine extracts boost cytotoxicity in vivo and have no effect in vitro while the opposite is true of pyridine residue material suggesting different mechanisms of NK augmentation by C. parvum between in vitro and in vivo systems.

Recognition by human and rabbit sera of common antigens to leukemia blast cells, peripheral blood B-lymphocytes, and monocytes

A human serum (obtained from a multiparous and multiple-transfused patient with chronic myelogenous leukemia) and a rabbit antiserum (obtained by immunization with papain extracts from a B-lymphoblastoid cell line) showed reactivity against antigenic specificities (different from HLA) expressed on peripheral blood B-lymphocytes, unmarked lymphocytes, and monocytes. These antigenic determinants were expressed on myeloblasts and lymphoblasts from patients with acute leukemia (during the active phase of their disease) and on B-lymphoblastoid cell lines and lymphocytes from patients with chronic lymphocytic leukemia. Purified peripheral blood T-lymphocytes, mitogen (phytohemagglutinin)-activated T-lymphocytes, and lymphoblasts (with T-cell characteristics) obtained from patients with acute lymphoblastic leukemia or established lymphoblastoid cell lines lacked these antigenic specificities. Absorption experiments indicate that the antigen(s) detected on normal mononuclear cell populations, leukemia cells, and B-lymphoblastoid cell lines were either identical or highly cross-reactive.