Momentum-independent magnetic excitation continuum in the honeycomb iridate H3LiIr2O6.

Understanding the interplay between the inherent disorder and the correlated fluctuating-spin ground state is a key element in the search for quantum spin liquids. H3LiIr2O6 is considered to be a spin liquid that is proximate to the Kitaev-limit quantum spin liquid. Its ground state shows no magnetic order or spin freezing as expected for the spin liquid state. However, hydrogen zero-point motion and stacking faults are known to be present. The resulting bond disorder has been invoked to explain the existence of unexpected low-energy spin excitations, although data interpretation remains challenging. Here, we use resonant X-ray spectroscopies to map the collective excitations in H3LiIr2O6 and characterize its magnetic state. In the low-temperature correlated state, we reveal a broad bandwidth of magnetic excitations. The central energy and the high-energy tail of the continuum are consistent with expectations for dominant ferromagnetic Kitaev interactions between dynamically fluctuating spins. Furthermore, the absence of a momentum dependence to these excitations are consistent with disorder-induced broken translational invariance. Our low-energy data and the energy and width of the crystal field excitations support an interpretation of H3LiIr2O6 as a disordered topological spin liquid in close proximity to bond-disordered versions of the Kitaev quantum spin liquid.

Quantitative analysis of taste disorder in COVID-19 patients, the hypersensitivity to salty quality.

Recently, many of the studies have illustrated that the new pandemic SARS-CoV-2 can affect Central Nervous System through the olfactory bulb. In addition to investigating anosmia or hyposmia induced by this virus, a quantitative analysis was needed to clarify the taste and smell disorder of the new coronavirus. The four basic taste quality with five concentrations for sweet, sour, bitter, and salty were administered to 75 subjects divided into three groups: COVID-19 patients with taste disorder, COVID-19 patients without taste disorder, and control group. The results indicated the increment of sweet (2.68 ± 0.14), sour (3.34 ± 0.12) and bitter (3.39 ± 0.2) thresholds in COVID-19 patients with taste disorder in comparison with patients without taste disorder that the threshold were: 2 ± 0.16, 2.11 ± 0.2 and 2.55 ± 0.5 for sweet, sour, and bitter respectively. On the other hand, the patients inversely showed a significant decrease in the salty taste threshold (0.51 ± 0.03) compared to COVID-19 positive control groups (1.11 ± 0.11). Additionally, despite taste disorder in almost all of the patients with smell deficiency, only 30% of cases with taste disorder reported smell deficiency. It may be concluded that some of the taste disorders in patients with COVID-19 disorder could be associated with taste receptors dysfunction or the spread of infection to the cranial nerves responsible for the conduction of tastes sensation.

Tetracyclines: drugs with huge therapeutic potential.

Tetracyclines are an amazing class of chemical agents with multiple therapeutic potential. Structural modification of the original natural tetracyclines led to the synthesis and development of doxycycline and minocycline, compounds with higher lipophilicity, better oral pharmacokinetics and higher potency. Due to diverse pharmacological properties, these drugs are now under extensive investigation for use in the treatment of various disparate diseases. In recent years, several studies have conclusively reported anti-inflammatory, immune-modulating and neuroprotective effects of these compounds. There are currently over 200 ongoing clinical trials on tetracyclines. These studies extend over a wide range of diseases including dermatological diseases, behavior and mental disorders, immune system disorders, cardiovascular diseases, and cancer. In this review we will discuss the chemistry and pharmacology of these agents, and describe how their inhibitory effect on matrix metalloproteinase and on pro-inflammatory cytokines has kindled renewed interest in them. Based on the reports from pre-clinical and clinical trials, the therapeutic potential and application of tetracyclines may well be redefined and extensively extended.

Type of cell death and the role of acetylcholinesterase activity in neurotoxicity induced by paraoxon in cultured rat hippocampal neurons.

Organophosphate (Ops) neurotoxicity is attributed both to its well-known cholinergic and non-cholinergic effects. In the present study we compared enzymatic and morphologic changes in neurons exposed to paraoxon during one day and one week. The effect of exposure time is important in neurotoxicity of Ops. The longer the exposure time is the more damage is observed in neurons, although there are few investigations about the effect in the post-exposure period. Hippocampal cells were obtained from rat neonates and cultured in Neurobasal/B27. Paraoxon at 50 and 100 microM were added. Inverted microscope and electron microscope were used to study cell morphology and Neutral Red staining was used to measure viability. We also assayed caspase-3 and (acetylcholinesterase) AChE activity. Hoechst staining was utilized to determine the type of cell death. Culture medium was replaced after 24 h in one-day group, however, tests were all carried out at the end of the first week in both group. The results indicate that paraoxon reduced the viability in a dose-dependent manner. Our results do not confirm apoptosis in either group; it seems that the cell death in one-day exposure group was not AChE dependent. In conclusion, present data imply that the toxicity of paraoxon is both dose and duration dependent, which may even remain after the cessation of exposure.

Arsenic rich iron plaque on macrophyte roots--an ecotoxicological risk?

Arsenic is known to accumulate with iron plaque on macrophyte roots. Three to four years after the Aznalcóllar mine spill (Spain), residual arsenic contamination left in seasonal wetland habitats has been identified in this form by scanning electron microscopy. Total digestion has determined arsenic concentrations in thoroughly washed 'root+plaque' material in excess of 1000 mg kg(-1), and further analysis using X-ray absorption spectroscopy suggests arsenic exists as both arsenate and arsenite. Certain herbivorous species feed on rhizomes and bulbs of macrophytes in a wide range of global environments, and the ecotoxicological impact of consuming arsenic rich iron plaque associated with such food items remains to be quantified. Here, greylag geese which feed on Scirpus maritimus rhizome and bulb material in areas affected by the Aznalcóllar spill are shown to have elevated levels of arsenic in their feces, which may originate from arsenic rich iron plaque.

Estimating and correcting mie scattering in synchrotron-based microscopic fourier transform infrared spectra by extended multiplicative signal correction.

We present an approach for estimating and correcting Mie scattering occurring in infrared spectra of single cells, at diffraction limited probe size, as in synchrotron based microscopy. The Mie scattering is modeled by extended multiplicative signal correction (EMSC) and subtracted from the vibrational absorption. Because the Mie scattering depends non-linearly on alpha, the product of the radius and the refractive index of the medium/sphere causing it, a new method was developed for estimating the Mie scattering by EMSC for unknown radius and refractive index of the Mie scatterer. The theoretically expected Mie contributions for a range of different alpha values were computed according to the formulae developed by Van de Hulst (1957). The many simulated spectra were then summarized by a six-dimensional subspace model by principal component analysis (PCA). This subspace model was used in EMSC to estimate and correct for Mie scattering, as well as other additive and multiplicative interference effects. The approach was applied to a set of Fourier transform infrared (FT-IR) absorbance spectra measured for individual lung cancer cells in order to remove unwanted interferences and to estimate ranges of important alpha values for each spectrum. The results indicate that several cell components may contribute to the Mie scattering.

A biologically inspired modular structure to control the sit-to-stand transfer of a biped robot.

In this study, a biologically inspired control structure to control the sit-to-stand (STS) transfer from a chair is developed and simulated. STS movement is consisted of two main phases. First phase of the movement is before leaving the seat (seat-off moment). In this phase seat reactions forces act on the body parts which are in contact with the seat. The second phase is after seat-off, where the only external forces acting on the body are ground reaction forces. A proper control algorithm of the STS transfer needs to consider switching between these two phases, which correspond to two different dynamical structures. The control structure developed and discussed in this work is based on the MOSAIC structure, proposed first by Wolpert and Kawato [1]. Original MOSAIC structure has a modular architecture which is based on multiple pairs of forward and inverse models of the dynamical system to be controlled, and each module is trained separately to learn one part of a given task. The number of effective modules is predetermined. We have developed a new method to train all modules simultaneously. This method is based on reinforcement and cooperative competitive learning, and the number of effective modules is determined automatically. In this study, the simulation was begun with four modules. Our results showed that only two modules out of four were selected to control the STS task. Responsibility of controlling the task was switched between the two modules around the seat-off moment.

Surgical approach to vascular complications of intravenous drug abuse.

OBJECTIVE: To assess the complications related to intravenous drug abuse. DESIGN: Prospective study. METHODS: Intravenous drug abusers (IVDAs) with vascular complications were assessed. RESULTS: Sixty-two patients presented with swelling and tenderness in the groin, and 3 patients with similar lesions in the cubital fossa. Infected pseudoaneurysms and deep vein thrombosis (DVTs) were diagnosed in 41 and 31 patients respectively (27 patients had both lesions). In patients with infected pseudoaneurysms, 9 patients underwent excision with early revascularization and 32 patients underwent ligation without revascularization. For all patients with femoral vein thrombosis ligation and excision was performed. 4 patients with pure DVTs were managed conservatively. Disabling claudication occurred in 6 patients. Four of them underwent late revascularization with an acceptable outcome. CONCLUSIONS: Ligation without revascularization is the appropriate treatment of infected pseudoaneurysms in IVDAs. Late revascularization is of great importance in patients with disabling claudication after treatment of addiction. Pure septic DVTs can be managed conservatively.

Paraoxon-induced ultrastructural growth changes of rat cultured hippocampal cells in neurobasal/B27.

Organophosphates (OPs) neurotoxicity is attributed both to their well-known cholinergic and recently attended non-cholinergic effects. Since parathion has been observed to be responsible for more cases of poisoning than any other OP insecticides, it is vitally important to investigate other mechanisms, besides cholinesterase inhibition, which can potentially contribute to the neurotoxicity of parathion (or its metabolite, paraoxon). In present study, hippocampal cells obtained from Wistar rat neonates were cultured in neurobasal medium supplemented with B27 serum where different doses of paraoxon were also introduced. The neuronal growth in the control group and those exposed to paraoxon was compared. Phase contrast microscopy, cell staining (Neutral Red) and computer assessment morphometric study (Motic) were used to study cell morphology, viability and type of cell death. Statistical analysis was carried out using one-way ANOVA. There was no clear morphologic differences between neurons in the control group and those exposed to 10 microM paraoxon; however, deformity of the soma was clear in pellets containing higher concentration of paraoxon. Ultrastructure of cells was markedly altered at 50 microM dose of paraoxon as evidenced by gradual discontinuation of cytoplasm, appearing of numerous vacuoles and intracytoplasmic myelin figure. The processes (neurites) did not grow in media containing 100 microM paraoxon or more. Viability decreased with increasing paraoxon especially above 100 microM. In conclusion, the present data reveal that paraoxon, in 30 microM or higher concentrations, induces a decrease in cell growth, followed by cell swelling and neuronal death (possibly necrosis).

Prediction of lupus nephritis in patients with systemic lupus erythematosus using artificial neural networks.

Artificial neural networks are intelligent systems that have been successfully used for prediction in different medical fields. In this study, efficiency of neural networks for prediction of lupus nephritis in patients with systemic lupus erythematosus (SLE) was compared with a logistic regression model and clinicians' diagnosis. Overall accuracy, sensitivity and specificity of the optimal neural network were 68.69, 73.77 and 62.96%, respectively. Overall accuracy of neural network was greater than the other two methods (P-value < 0.05). The neural network was more specific in predicting lupus nephritis (P-value < 0.01), but there was no significant difference between sensitivities of the three methods. Sensitivities of all three methods were greater than their specificities. We concluded that neural networks are efficient in predicting lupus nephritis in SLE patients.

Target cells for methylsulphonyl-2,6-dichlorobenzene in the olfactory mucosa in mice.

Previously we reported that methylsulphonyl-2,6-dichlorobenzene, 2, 6-(diCl-MeSO(2)-B), was irreversibly bound to the olfactory mucosa of mice and induced necrosis of the Bowman's glands with subsequent neuroepithelial degeneration and detachment. In this study, autoradiography and histopathology were used to determine tissue-localization and toxicity of 2,6-(diCl-MeSO(2)-B) in the olfactory mucosa of control mice and animals pretreated with cytochrome P450 (CYP) and glutathione (GSH) modulators. The Bowman's glands of the olfactory mucosa were the major target sites of non-extractable binding of 2,6-(diCl-(14)C-MeSO(2)-B), whereas the olfactory neuroepithelium and nerve bundles showed only background levels of silver grains. Metyrapone pretreatment slightly decreased binding in the Bowman's glands and markedly decreased toxicity in the olfactory mucosa after 2,6-(diCl-MeSO(2)-B) administration. These results support that a CYP-mediated activation of 2, 6-(diCl-MeSO(2)-B) takes place in the Bowman's glands giving rise to toxic reactive intermediates. In mice pretreated with the GSH-depleting agent phorone, a marked increase of irreversible binding of 2,6-(diCl-(14)C-MeSO(2)-B) in the Bowman's glands was observed. Tape-section autoradiograms also revealed a significant increase of uptake of radioactivity in the olfactory bulb. As determined by histopathology, GSH-depletion increased both the extent and severity of the lesion in the mucosa. These results imply that 2,6-(diCl-MeSO(2)-B)-reactive intermediates are conjugated with GSH. The amount of irreversible binding and toxicity in the olfactory mucosa seems to be associated with the level of 2, 6-(diCl-MeSO(2)-B)-reactive intermediates.

Biomechanical analysis of sit-to-stand transfer in healthy and paraplegic subjects.

OBJECTIVE: An experimental study of the sit-to-stand transfer in healthy adults with/without arm-support and in paraplegic patients with/without electrical stimulation of the quadriceps muscles was performed. The study was aimed to compare the joint torques, momentum transfer hypothesis, and stability of the sit-to-stand transfer in the healthy and paraplegic subjects. METHODS: A planar 3-linkage rigid body model was used to compute the body-segmental linear momentum and the reaction forces and torques at the joints from measured data. RESULTS: In healthy subjects the arm-support enlarged the support base of the body and thus, increased the postural stability. Strong arm-assistance reduced the maximum hip and knee joint torques by more than 50%. It was observed that the healthy participants rising with arm-support used momentum transfer to facilitate the transition from sitting to standing. The paraplegic participants did not apply the momentum transfer strategy and the sit-to-stand transfer was accomplished in a quasi-static manner. Stimulating the quadriceps, the legs could participate partly in the movement dynamics. CONCLUSION: Our results indicate that some significant differences exist between the maneuver applied by the paraplegic patients to stand up and the strategies used by the healthy adults rising with arm-support. RELEVANCE: Analysis of the biomechanical factors underlying the sit-to-stand activity is essential in the design of competent closed-loop neuroprosthesis controllers which assist paraplegic patients during rising.

Persistent olfactory mucosal metaplasia and increased olfactory bulb glial fibrillary acidic protein levels following a single dose of methylsulfonyl-dichlorobenzene in mice: comparison of the 2,5- and 2, 6-dichlorinated isomers.

Histopathology was used to characterize long-term toxic effects in the olfactory system following a single ip dose (4-65 mg/kg) of methylsulfonyl-2,6-dichlorobenzene, (2,6-(diCl-MeSO(2)-B)), in female NMRI mice. The effects of 2,6-(diCl-MeSO(2)-B) and its 2, 5-chlorinated isomer, (2,5-(diCl-MeSO(2)-B)), on the levels of glial fibrillary acidic protein (GFAP; a biomarker for neurotoxicity) in different brain regions were examined by an enzyme-linked immunosorbent assay (ELISA). The histopathologic effects of 2, 6-(diCl-MeSO(2)-B) were dose-, time-, and tissue-dependent. At the highest doses (16-65 mg/kg), the initial effect of 2, 6-(diCl-MeSO(2)-B) was necrosis of the Bowman's glands, followed by a sequence of secondary events including degeneration of the olfactory neuroepithelium, repopulation of the basement membrane by a ciliated respiratorylike epithelium, fibrosis and ossification in the lamina propria, formation of bilateral polyps, angiogenesis, and disappearance of nerve bundles. Remodeling was most pronounced in the dorsal meatus of the olfactory mucosa and persisted for the duration of the experiment (46 weeks). A dose-dependent induction of GFAP in the olfactory bulb of mice treated with 2,6-(diCl-MeSO(2)-B) was observed at all doses examined (16-65 mg/kg). GFAP levels were highest 2 weeks after treatment (eightfold induction at 65 mg/kg) and then gradually decreased to normal within 26 weeks. The 2, 5-substituted isomer (65 mg/kg) did not induce GFAP in the olfactory bulb and or toxicity in the olfactory mucosa. In conclusion, a single dose of 2,6-(diCl-MeSO(2)-B) results in persistent metaplasia and remodeling of the olfactory mucosa, and a long-lasting but transient induction of GFAP in the olfactory bulb. It is proposed that methylsulfonyl-2,6-dichlorobenzene may serve as an experimental tool with a unique ability to produce persistent primary and/or secondary lesions in the olfactory system of mice.

Localization and comparative toxicity of methylsulfonyl-2,5- and 2,6-dichlorobenzene in the olfactory mucosa of mice.

Several methylsulfonyl (MeSO2) metabolites formed from chlorinated aromatic hydrocarbons have been identified in human milk, lung, and body fat, as well as in the tissues of Baltic grey seals and arctic polar bears. The tissue localization and nasal toxicity of two methylsulfonyl-substituted dichlorobenzenes (diCl-MeSO2-B), with the chlorine atoms in the 2,5-, and 2,6- positions, were investigated in female NMRI and C57B1 mice. Using tape-section autoradiography, animals dosed i.v. with 14C-labeled 2,5-, or 2,6-(diCl-MeSO2-B) showed a preferential uptake of radioactivity in the olfactory mucosa and the tracheobronchial epithelium. Histopathology showed that 2,6-(diCl-MeSO2-B) is a potent toxicant that induces necrosis in the olfactory mucosa following a single dose as low as 4 mg/kg (i.p. injection), whereas 2,5-(diCl-MeSO2-B) induced no signs of toxicity in the olfactory mucosa at doses as high as 130 mg/kg (i.p. injection). Necrosis of the Bowman's glands was the first sign of 2,6-(diCl-MeSO2-B)-induced toxicity followed by degeneration of the neuroepithelium, which implies that the Bowman's gland may be the primary site of toxicity and degeneration of the neuroepithelium may be a secondary effect. Administration of the parent compounds, 1,3-dichlorobenzene and 1,4-dichlorobenzene, or the chlorinated analog 1,2,3-trichlorobenzene (85, 85, and 105 mg/kg, respectively; i.p. injection), induced no signs of toxicity in the olfactory mucosa. These and previous results suggest that 2,6-positioned chlorine atoms and an electron withdrawing substituent in the primary position is an arrangement that predisposes for toxicity in the olfactory mucosa.

[Chronic pulmonary heart disease and its risk factors among a worker population in Teheran]. / Le coeur pulmonaire chronique et ses facteurs de risque dans une population ouvrière de Téhéran

Because of the high frequency of chronic cor pulmonale in workers admitted to the cardiology department of the Khazaneh Hospital in Teheran, we studied the clinical aspect and the risk factors of this disease in 66 male patients. The average age of patients was 56.1 years and they often had a long history of bronchitis isolated or associated with emphysema. The ECG analysis showed that most abnormalities were localized on the QRST wave. Tobacco and a polluted working environment were the factors most frequently met in our patients. The opium habit probably acted as a risk factor for chronic bronchopneumopathy, but further studies are necessary to ascertain the fact.