Microphase separation of living cells.

Self-organization of cells is central to a variety of biological systems and physical concepts of condensed matter have proven instrumental in deciphering some of their properties. Here we show that microphase separation, long studied in polymeric materials and other inert systems, has a natural counterpart in living cells. When placed below a millimetric film of liquid nutritive medium, a quasi two-dimensional, high-density population of Dictyostelium discoideum cells spontaneously assembles into compact domains. Their typical size of 100 µm is governed by a balance between competing interactions: an adhesion acting as a short-range attraction and promoting aggregation, and an effective long-range repulsion stemming from aerotaxis in near anoxic condition. Experimental data, a simple model and cell-based simulations all support this scenario. Our findings establish a generic mechanism for self-organization of living cells and highlight oxygen regulation as an emergent organizing principle for biological matter.

Mutations in known disease genes account for the majority of autosomal recessive retinal dystrophies.

Retinal dystrophies (RDs) are hereditary blinding eye conditions that are highly variable in their clinical presentation. The remarkable genetic heterogeneity that characterizes RD was a major challenge in establishing the molecular diagnosis in these patients until the recent advent of next-generation sequencing. It remains unclear, however, what percentage of autosomal recessive RD remain undiagnosed when all established RD genes are sequenced. We enrolled 75 families in which RD segregates in an apparently autosomal recessive manner. We show that the yield of a multigene panel that contains known RD genes is 67.5%. The higher yield (82.3%) when whole exome sequencing was implemented instead was often due to hits in genes that were not included in the original design of the panel. We also show the value of homozygosity mapping even during the era of exome sequencing in uncovering cryptic mutations. In total, we describe 45 unique likely deleterious variants (of which 18 are novel including one deep intronic and one genomic deletion mutation). Our study suggests that the genetic heterogeneity of autosomal recessive RD is approaching saturation and that any new RD genes will probably account for only a minor role in the mutation burden.

Vitreous levels of placental growth factor correlate with activity of proliferative diabetic retinopathy and are not influenced by bevacizumab treatment.

PurposePlacental growth factor (PlGF) is a member of the VEGF family that plays an important role in experimental models of diabetic retinopathy and retinal neovascularization. We aimed to investigate whether vitreous levels of PlGF correlated with proliferative diabetic retinopathy (PDR) status, VEGF levels, and bevacizumab treatment. We also analysed PDR membranes to confirm the presence of the PlGF receptor, FLT1, in endothelial cells.MethodsThis was a case-control study: undiluted vitreous fluid samples were obtained from 28 active PDR patients without preoperative bevacizumab treatment, 21 active PDR patients with preoperative bevacizumab treatment, 18 inactive PDR patients, and 21 control patients. PlGF and VEGF levels in samples were determined by enzyme-linked immunosorbent assay. Immunohistochemistry for FLT1 was performed on human PDR membranes.ResultsCompared to control, vitreous PlGF levels were higher in both active PDR without bevacizumab (P<0.0001) and with bevacizumab (P<0.0001). There was no significant difference in PlGF between active PDR patients without and with bevacizumab (P=0.56). Compared to active PDR, PlGF levels were significantly reduced in inactive PDR (P=0.004). PlGF levels were highly correlated with VEGF levels in active PDR. VEGFR1 was expressed in endothelial cells in human PDR membranes.ConclusionThe strong correlation of PlGF levels with PDR disease status and expression of FLT1 in human PDR membranes suggest that PlGF has a pathogenic role in proliferative diabetic retinopathy. Therapeutic targeting of PlGF with agents like aflibercept may be beneficial.

Neutron energy spectrum adjustment using deposited metal films on Teflon in the miniature neutron source reactor.

The focus of this article was on the experimental estimation of the neutron energy spectrum in the inner irradiation site of the miniature neutron source reactor (MNSR), using, for the first time, a selected set of deposited metal films on Teflon (DMFTs) neutron detectors. Gold, copper, zinc, titanium, aluminum, nickel, silver, and chromium were selected because of the dependence of their neutron cross-sections on neutron energy. Emphasis was placed on the usability of this new type of neutron detectors in the total neutron energy spectrum adjustment. The measured saturation activities per target nucleus values of the DMFTs, and the calculated neutron spectrum in the inner irradiation site using the MCNP-4C code were used as an input for the STAY'SL computer code during the adjustment procedure. The agreement between the numerically calculated and experimentally adjusted spectra results was discussed.

UVB exposure enhanced the dermal penetration of zinc oxide nanoparticles and induced inflammatory responses through oxidative stress mediated by MAPKs and NF-κB signaling in SKH-1 hairless mouse skin.

Besides titanium dioxide (TiO2), zinc oxide (ZnO) nanoparticles (NPs) are commonly used in sunscreen formulations as protective agents against exposure to ultraviolet radiation. Although the majority of prior studies have concluded that NPs do not penetrate healthy skin, compromised skin slightly enhanced metal oxide NP penetration. However, a question arises regarding the possible toxic consequences if consumers who had applied sunscreens containing ZnO-NPs were exposed to environmentally relevant doses of UVB. Considering this, we planned a study where SKH-1 hairless mice were topically exposed to a 5% and/or 10% dose of ZnO-NPs (<50 nm and <100 nm) either alone or along with UVB (50 mJ cm-2). In two additional groups, mice were treated with either bulk ZnO-NPs (<5 µm) or with ZnO-NPs (<5 µm) and subsequently UVB (50 mJ cm-2). Animals of all groups were sacrificed after 6, 24 and 48 h and the Zn ion content in the skin was measured. In addition, estimation of ROS generation, histopathology, myeloperoxidase (MPO) activity, immunohistochemistry for COX-2 and western blot analysis for MAPKs, p-IκBα, p-NF-κB, and COX-2 were also carried out. Significant increases in the Zn ion in exposed skin were seen. Enhanced ROS generation and MPO activity were also found in ZnO-NPs followed by UVB exposed groups at all three time points. Similarly, hyperplasia and over-expression of COX-2 were also greater in ZnO-NPs and UVB exposed groups than in the ZnO-NPs and UVB only groups. The expression of MAPKs, and transcription factors NF-κB along with COX-2 were also enhanced significantly in ZnO-NPs and the UVB treated group. Collectively, our findings suggest that UVB exposure enhanced ZnO-NP penetration in mouse skin and possibly dissolution of these ZnO-NPs takes place during this process, causing significant Zn ion generation leading to oxidative stress by ROS generation which subsequently activates MAPK-NF-κB signaling and increases COX-2 and inflammation.

Study the effect of beryllium reflector poisoning on the Syrian MNSR.

Neutron interactions with beryllium lead to formation of (3)H and strong neutron absorbers (3)He and (6)Li in the reflector (so called beryllium poisoning). After the reactor shutdown, the concentration of (3)He increases in time due to tritium decay. This paper illustrates the impact of poisoning accumulation in the beryllium reflectors on reactivity for the Syrian MNSR research reactor. The prediction of (6)Li and (3)He poison concentrations, initiated by the 9Be(n,α) reaction, in the beryllium reflectors of the MNSR was also presented. The results were based on MCNP Monte Carlo calculations and solutions to the differential equations which describe the time dependent poison concentrations as a function of reactor operation time and shutdown periods. The whole reactor history was taken into account to predict reliable values of parasitic isotope concentrations. It was found that the (3)He and (6)Li accumulations in the beryllium reflectors during the actual working history decreased the excess reactivity by about 28%. While, the effect became more significant at the reactor life's end and the reactor became subcritical after 25,000 h operation. The results contained in this paper could be used in assess the safety analysis of the MNSR reactor.

Potential penetration of topical ranibizumab (Lucentis) in the rabbit eye.

PURPOSE: To assess ranibizumab (Lucentis) penetration into the retina after topical administration in a rabbit model. METHODS: Ranibizumab was topically applied to the right eye of rabbits according to three regimens: every 2 h (q2hr), four times daily (qid), and twice daily (bid). Intraocular penetration of ranibizumab was assessed at 3, 7, 14, 21, and 28 days following initiation of drops. At each time point, the anterior chambers, vitreous cavities, and blood of one of the rabbits from each subgroup were sampled for ranibizumab detection using enzyme-linked immunosorbent assay (ELISA), and both eyes were then enucleated for ranibizumab detection in the retina by confocal immunohistochemistry (CI). Another group of rabbits received intravitreal ranibizumab and was similarly sampled for comparison. RESULTS: CI showed ranibizumab staining in the right retina after 7 and 14 days of q2hr topical administration in two out of four experiments. No ranibizumab was detected in the left retina at any of the sampling time points. ELISA was positive in the vitreous of the right eye at 14 and 21 days in the q2hr treated rabbits in one out of four experiments. No ranibizumab was detected in the qid and bid subgroups. CI and ELISA of the aqueous and vitreous were consistently positive in the intravitreal group. Mild ranibizumab levels were detected in the blood in both the topical and intravitreal groups. CONCLUSIONS: Topically applied ranibizumab can be detected in the retina following high-frequency administration in a rabbit model. A trans-scleral route of penetration is suggested.

Core conversion analyses of the Syrian MNSR reactor from HEU to LEU and MEU fuel with homogeneously mixed burnable poisons.

A comprehensive analysis has been performed to investigate the conversion of the Syrian MNSR (miniature neutron source reactor) from current HEU fuel to selected alternatives LEU and MEU fuels. For this purposes the core design calculations related to design and engineering of LEU and MEU fuels have been carried out using the codes WIMSD/4 and BORGES-part of the MTR-PC and the code CITATION. Aiming at reducing the fuel enrichment by maintaining reactor power, thermal neutron flux and excess reactivity in the same range of the current MNSR design, two fuel alternatives of LEU (UO(2)-Mg) and MEU (U(3)Si(x)-Al) have been investigated. The results indicate that the first type (UO(2)-Mg) realizes the criticality conditions with low enrichment of 20% using the similar overall design of the present HEU fuel pins, whereas the second type (U(3)Si-Al) requires increasing the enrichment up to 33%. For the purpose of reactor core lifetime extension the possibility of mixing the burnable poisons Gd(157) and Cd(113) in the fresh core has been also explored. Thus, the calculation results indicate that the long-term control effect of Cd(113) on the excess reactivity is more homogeneous over the time due to the lower burn up rate of this burnable poison.

Analysis of MNSR core composition changes using the codes WIMSD-4 and CITATION.

The codes WIMSD/4 and BORGES--part of the MTR-PC code package--have been applied to prepare the microscopic cross-section library for the main elements of miniature neutron source reactor (MNSR) core for six neutron energy groups. The generated library has been utilized by the 3D code CITATION to perform the calculation of fuel burn-up including the identification of main fission products and their impacts on the multiplication factor. In this regard some modifications have been introduced to the subroutine NUCY in CITATION to incorporate estimating the concentration of the related actinides and fission products. The burn-up results have indicated that the core life-time of MNSR is being mainly estimated by Sm(149) followed by Gd(157) and Cd(113). The accumulation of these fission products during 100 continuous operation days caused a reduction of about 4.3 mk for the excess reactivity. This result seems to be in good agreement with the available empirical value of 3.5 mk, which relates to the whole discontinuous operation period of the reactor since its start up to now. The calculation procedure simulates the sporadic operation with an equivalent continuous operation period. This approximation is valid for the long-lived fission products that mainly dictate the core life-time. However, it is an overestimation for the concentration of short-lived radioactive products like Xe(135).

Virus-induced chalazion.

PURPOSE: To investigate a viral etiology in certain chalazia. METHODS: A prospective study over 7.5 years of all newly presenting chalazia associated with diffuse follicular conjunctivitis but without any other aetiological factors. Patients were investigated for ocular or systemic infections by history, physical exam, slit-lamp exam, and/or histology of conjunctival biopsy (including transmission electron microscopy). RESULTS: A total of 27 patients developed follicular conjunctivitis without meibomian gland dysfunction, blepharitis, or sexually transmitted diseases. Evidence for a viral aetiology included: recent systemic viral illness (15/27), recent contact with subjects with chalazia or follicular conjunctivitis (5/27), preauricular lymphadenopathy (4/27), viral corneal disease (4/27), or viral particles by ultrastructure (4/4). CONCLUSIONS: Chalazia may be associated with viral conjunctivitis. Intralesional corticosteroids should be considered with great caution for viral-induced chalazia.

Pathology and pathogenesis of retinal detachment.

Retinal detachment, separation of the neurosensory retina from the underlying retinal pigment epithelium, is a sight threatening condition that is considered one of the few ocular emergencies. The literature is enormously rich in studies that focused on different aspects of this disease process. Yet certain aspects remain largely unanswered. We briefly review major aspects of retinal detachment and discuss various important contributions in this field, focussing mainly on the pathogenesis of and predisposing factors to retinal detachment, and on the pathologic changes that occur following its development and following various surgical procedures currently used in its management.

Clinicopathologic studies of age-related macular degeneration with classic subfoveal choroidal neovascularization treated with photodynamic therapy.

BACKGROUND: Photodynamic therapy (PDT) is a relatively new modality that is currently under clinical and experimental evaluation for treatment of subfoveal choroidal neovascularization (CNV). The authors report the case of an 82-year-old woman who underwent verteporfin-mediated PDT for classic subfoveal CNV. Fluorescein angiography performed 2 weeks after treatment disclosed reduction of the initial area of neovascularization and leakage by approximately 60%. Three weeks after PDT, however, the area of leakage was almost the same size as that before treatment. The patient underwent submacular membranectomy almost 4 weeks after treatment. The authors describe the ultrastructural vascular changes after PDT and a clinicopathologic study of classic CNV. METHODS: The submacular membrane was studied by light and electron microscopy and immunohistochemical techniques. RESULTS: Ultrastructural examination of the peripheral vessels showed evidence of endothelial cell degeneration with platelet aggregation and thrombus formation. Occasional occluded vessels were surrounded by macrophages, a phenomenon previously reported to describe the process of resorption of such blood vessels. The vessels in the center of the membrane were unremarkable. CONCLUSION: Photodynamic therapy causes endothelial cell damage, thrombus formation, and vascular occlusion of classic CNV in age-related macular degeneration.

Electroconvulsive therapy for minors: experiences and attitudes of child psychiatrists and psychologists.

OBJECTIVE: To estimate knowledge, experience, and attitudes towards the use of electroconvulsive treatment in minors (patients < 18 years of age), among child and adolescent psychiatrists and psychologists. METHOD: 1,600 questionnaires were mailed to a group of child and adolescent psychiatrists and psychologists. RESULT: There were 625 (39%) respondents. 329 (53.8%) of the respondents stated that they possessed minimal knowledge about the use of ECT in children and adolescents. Lack of confidence in providing a second opinion was common and reported by 75%. Compared with those with minimal knowledge, respondents with advanced knowledge reported a higher perception of safety and efficacy. The majority (70%) of the respondents regarded ECT as a treatment of last resort. CONCLUSION: Many child and adolescent psychiatrists and psychologists have very little knowledge, training, or experience in this treatment. They seem to be ill equipped to appropriately consider or advise patients and families about ECT. Clinical and research implications of these findings are discussed.

"Jampolsky Syndrome": superior rectus overaction-contracture syndrome: prevalence, characteristics, etiology and management.

BACKGROUND AND PURPOSE: To further describe the Superior Rectus Overaction/Contracture Syndrome (SRSy) first described by Jampolsky in 1964. METHODS OF STUDY: Twenty-five patients demonstrating findings characteristic of an isolated SRSy of various etiologies, but unrelated to superior oblique palsy or dissociated vertical deviation DVD, are reported. Eleven patients had surgery, consisting of superior rectus (SR) recession in ten patients and a Knapp procedure to the fellow eye (with presumed diagnosis of double elevator palsy) in one patient. RESULTS: Of the 10 patients who had SR recession of the affected eye, 9 were satisfactorily alleviated of their vertical deviation with elimination of the forced tilt difference, whereas one patient developed the SRSy in the fellow eye soon after surgery. The patient who had the Knapp procedure to the fellow eye showed, one week postoperatively, full sursumduction of that eye with significant bilateral DVD. CONCLUSION: SRSy is a common syndrome of several various etiologies. Not infrequently, whether or not associated with DVD, it may masquerade as weakness of the contralateral inferior oblique and/or superior rectus muscles. The treatment of choice is weakening of the overacting contracted SR muscle.

Brain angiotensin and the female reproductive cycle.

The results consistently show from experiment to experiment that there is a surge of brain Ang II prior to the well known preovulatory LH surge. It should be pointed out that these experiments have been carried out by two different laboratories and with the help of different experimenters and some of the experiments have been repeated. Therefore, the consistency of the results is reassuring. It does appear that Ang II increases in the brain, specifically in the hypothalamus, probably in cells of the paraventricular nucleus about 1 hour before the LH levels in plasma rise to a peak. Since LH release from the anterior pituitary gland is stimulated by the release of LHRH from the arcuate nucleus into the median eminence, the results would suggest that Ang II stimulates the release of LHRH. The peak in the OVX of Ang II treated rats is sharp and short-lasting with a second, later peak. The LH surge follows the first peak and a second rise in LH follows the second Ang II peak. These data suggest that brain Ang II synthesized and stored in the brain plays a critical role in the female reproductive cycle by initiating the LH surge. The regulation of Ang II may be by estrogen and progesterone, but as the increase in angiotensinogen mRNA was not marked, the surge of Ang II appears to result more from the sudden release of stored Ang II than its synthesis. Thus, the question is what releases Ang II. Earlier studies showed that catecholamines release Ang II from neurons and not from glia involving alpha 2 receptor blockade to increase norepinephrine by inhibiting reuptake (7). An interaction between catecholamines, Ang II and LH had also been suggested earlier (18, 19). Therefore, a series of events triggered by steroids in proestrus may begin with increases in norepinephrine activating neuronal alpha 2 receptors and precipitating release of brain Ang II. This is represented diagrammatically in Figure 15. The Ang II surge stimulates the cells containing GnRH (gonadotropin releasing hormone) in the arcuate nucleus. The effect of Ang II on multiple GnRH cells amplifies the effect and GnRH is released into the portal vessels of the pituitary to stimulate the large LH release, from gonadotrope cells in the anterior pituitary, into the plasma that produces the LH surge. The effect of the LH surge is ovulation which ends the estrogen build up.(ABSTRACT TRUNCATED AT 400 WORDS)

Variations in angiotensin-II release from the rat brain during the estrous cycle.

To investigate the hypothesis that the release of angiotensin-II (AII) in the rat brain increases on the day of proestrus, samples of cerebrospinal fluid (CSF) and interstitial fluid from the general region of the bed nucleus of the stria terminalis pars ventralis in the preoptic-anterior hypothalamic area were monitored for AII-immunoreactive material (AII-ir) using push-pull cannulas. Samples of CSF were obtained on the day of proestrus and diestrus day 1 at 30-min intervals from 1200-1600 h. Samples of interstitial fluid were obtained at 25-min intervals from 0930-1600 h. The rate of release of AII-ir into CSF was significantly greater on proestrus compared to diestrus day 1, and in the early afternoon of proestrus compared to the late afternoon. In five of seven rats and in the overall comparison of AII-ir release from the preoptic-anterior hypothalamic area, significantly more AII-ir was released on the day of proestrus vs. diestrus day 1. These observations are consistent with previous studies suggesting that brain AII may play a role in the regulation of LH release on the day of proestrus.