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.

Corrigendum to "Pneumocystis pneumonia in COVID-19 patients: A comprehensive review" [Heliyon 9(2) (February 2023) e13618]

[This corrects the article DOI: 10.1016/j.heliyon.2023.e13618.].

Latent infections, coronavirus disease 2019 and psychiatric disorders: The friend of my enemy

Recent reports revealed an increased rate of hospitalization and mortality of coronavirus disease 2019 (COVID-19) among patients with psychiatric disorders. On the other hand, there is a link between latent infections, including Toxoplasma gondii, herpes simplex virus type 1 (HSV-1) and cytomegalovirus (CMV) with psychiatric disorders. We individually assessed data regarding 1) the mortality rate of COVID-19 among individuals with psychiatric disorders; 2) the association of latent infections in COVID-19 patients and 3) the association between latent infections and psychiatric disorders. We developed the hypothesis that latent infection could increase the risk of severe COVID-19 among patients with psychiatric disorders. Cumulative evidence proposed that infection with toxoplasmosis, CMV and HSV-1 could increase the risk of severe acute respiratory syndrome coronavirus 2 (SARS-Co-V2) infections among patients with psychiatric disorders probably by induction of hyperinflammatory conditions. These infections are also associated with hyperinflammation and T cell exhaustion, which has also been observed in both schizophrenia and COVID-19. This hypothesis provides new insights into the role of latent infections in increasing the mortality rates of COVID-19 among individuals with psychiatric disorders. Strategies for screening, early diagnosis and treatment of these infections could be recommended for COVID-19 patients with a background of psychiatric disorders.

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.

Persistence assessment of SARS-CoV-2-specific IgG antibody in recovered COVID-19 individuals and its association with clinical symptoms and disease severity: A prospective longitudinal cohort study

Background

Antibodies play an important role in neutralizing invading pathogens and protecting the host against re-infection. Thus, the accurate assessment of antibodies during a pandemic can provide important evidence for monitoring pathogen exposure, understanding the role of antibodies in protective immunity, and helping vaccine development.

Methods

In this study, 96 west Iranian recovered COVID-19 subjects were recruited and, based on clinical symptoms and disease severity, categorized into three different groups: mild, moderate, and severe. In addition, the presence and dynamic change of SARS-CoV-2-specific IgG antibody three, four-, and six months post symptom onset (PSO) were measured. Also, the association between IgG antibody titer with clinical symptoms and disease severity was examined.

Results

Although in real-time RT-PCR-positive samples negative IgG antibody results were found, most subjects mount humoral immune responses that could raise a robust SARS-CoV-2-specific IgG antibody. Furthermore, this antibody persisted in the serum of most recovered COVID-19 subjects at least six months PSO and demonstrated little to no decrease. Also, specific IgG antibody titer was strongly correlated with clinical symptoms and disease severity.

Conclusions

These results provide an insight into the presence and persistence of the SARS-CoV-2-specific IgG antibody. Although serological tests could not be used as the primary diagnostic test, they may support real-time RT-PCR results. Also, they could be used for diagnosing COVID-19 subjects tested later outside of the optimal period. Thus, the SARS-CoV-2-specific IgG antibody is an excellent marker of COVID-19 infection or vaccination and provides an additional diagnostic tool for verifying results and helps monitor and control COVID-19 spread.

Seroepidemiological Study of Toxocariasis in Children Aged 6-14 Year Old in Sanandaj, Western Iran

Background:

Toxocariasis is a disease caused by Toxocara nematodes and occurs from consuming their eggs. The main hosts of these worms are dogs and cats. The disease in humans becomes a visceral larva migrans (VLM). This descriptive cross-sectional study was conducted to determine the prevalence of toxocariasis in children aged 6–14 years.

Methods:

This cross-sectional descriptive study was conducted from Jun 1 2016 to Dec 1 2017 in Sanandaj, west of Iran. A total of 182 serum samples were collected from children age 6 to14 yr referred to medical diagnostic laboratories. Demographic data (age, sex, and parents’ literacy status), clinical signs (cough, headache, fever, abdominal pain), and the history of contact with dogs and cats was collected by a questionnaire. The presence of anti-Toxocara IgG antibody was detected by T. canis IgG ELISA (IBL, Germany) kit.

Results:

Of 182 subjects, 97 (53.3%) were male and 85 (46.7%) female. The average age was 9.2 years. Antibodies against T. canis were positive in three cases (1.65%) of all the studied subjects.

Conclusions:

The results showed a low prevalence of toxocariasis in children studied.

Blastocystis, urticaria, and skin disorders: review of the current evidences

Blastocystis is one of the most common intestinal protozoan parasites worldwide, which is linked to cutaneous lesions and urticaria. In a setting of systematic review, the data on the association of Blastocystis infection with cutaneous lesions were searched in order to summarize the main clinical symptoms, diagnostic methods, treatment, and outcome of the patients. The search identified 28 eligible articles, including 12 cross-sectional studies and 16 case reports/case series (including 23 cases). A diverse spectrum of skin symptoms, mainly urticaria, rash, and itching, was reported from the studies. Of the 23 infected cases with the skin symptoms, gastrointestinal symptoms were reported from the 16 cases, whereas 7 cases with urticaria had asymptomatic infection. The most frequent subtypes were ST1, ST2, and ST3, respectively. Metronidazole, paromomycin, and tinidazole were the most prescribed drugs in patients with single Blastocystis infection. Notably, urticaria and other cutaneous symptoms of all treated patients were resolved after treatment. In conclusion, this study indicates that Blastocystis infection can be a neglected cause of urticaria and skin disorders. Since the treatment of Blastocystis infection is simple, screening and treatment of this infection should be considered in patients with urticaria and other skin disorders.

Molecular evidence for zoonotic transmission of Blastocystis subtypes in Kurdistan province, West of Iran

Blastocystis sp. is one of the most prevalent human parasites with a vast variety of non-human hosts. The aim of the present study was to determine the subtype distribution of Blastocystis in humans and trace the route of transmission by molecular data and phylogenetic analysis. Stool samples were collected from patients who referred to 14 medical laboratories in Kurdistan, Iran. All the samples were examined using the direct wet mount and formalinether concentration techniques. DNA extraction was carried out for 30 microscopically positive isolates and 33 negative samples. DNA amplification and subtype identification were also performed using the barcoding method and sequencing techniques. Of 1383 stool samples, 239 (17.3%) were infected with Blastocystis sp. Out of the 24 sequenced isolates, two (8.3%), six (25%), and 16 (66.6 %) belonged to the ST1, ST2, and ST3 subtypes, respectively. Bioinformatics analysis indicated that all the isolates were genetically similar to animal isolates. Blastocystis sp. was very common and ST1, ST2, and ST3 subtypes were prevalent in the study population. Bioinformatics analysis suggests that zoonotic transmission plays an important role in Blastocystis sp. distribution in Kurdistan province.

Giardia lamblia assemblages A and B isolated from symptomatic and asymptomatic persons in Hamadan, west of Iran

Giardia is a very abundant organism bringing about diarrhoea in human beings. The focus of this analysis was the detection of Giardia lamblia assemblages in human stool specimens in Hamadan, west of Iran, as well as the association between obtained assemblages and clinical symptoms. Faecal samples of 4066 individuals admitted to the medical and health care facilities in Hamadan were inspected microscopically for the existence of Giardia cysts/trophozoites, and the clinical symptoms of the patients were recorded. The DNA of positive samples was isolated from and the nucleotide sequences of both glutamate dehydrogenase (gdh) (n = 15) and triose phosphate isomerase (tpi) (n = 8) genes were analyzed. In direct microscopy, a total of sixty-four samples (1.6%), were considered as positive for G. lamblia cysts or trophozoites. The sequence analysis showed that 18 out of 23 sequenced isolates (78.2%) were assemblage A and 5 (21.7%) were assemblage B. Clinical symptoms were observed in 44.4% and 40% of patients with assemblages A and B, respectively. Overall, the predominant assemblage A detected in the tested samples along with bioinformatics analysis suggest a potential zoonotic transmission in the region of the study. Although advanced analyses are necessary to understand the foundation and path of the infection, it seems that more sanitary regulations regarding contact with livestock and pet animals are essential.

Prevalence and subtype identification of Blastocystis isolated from humans in Ahvaz, Southwestern Iran

AIM

The aim of the present study was to determine the prevalence and subtype distribution of Blastocystis and its relation with demographic data and symptoms in humans referred to medical centers in Ahvaz 2014-2015.

BACKGROUND

Infections with intestinal parasites are one of the most important threats to human health worldwide, especially in tropical and subtropical areas. Blastocystis sp. is a common parasite of humans with a vast variety of non-human hosts. We aimed to study the prevalence and subtypes of Blastocystis sp. in individuals referred to medical laboratories in Ahvaz city, southwest Iran.

METHODS

From September 2014 to September 2015, 618 stool samples were collected from 16 medical laboratories in Ahvaz, and examined using direct wet mount, formalin-ether concentration, a modified version of the Ziehl-Neelsen staining technique, and cultivation in xenic HSr + S medium. Subtypes of positive Blastocysts sp. were obtained using the "barcoding" method. The results were analyzed using SPSS software, version 16, with Chi-square and Fisher's exact test.

RESULTS

Totally, 325 (52.6%) of the referred individuals were men and 293 (47.4%) were women. Blastocystis sp. was observed in 146 (23.6%) samples. Co-infections with other intestinal parasites were found in 32 (5.17%) cases. Out of the 146 positive isolates, 20.83%, 20.83% and 58.34% belonged to ST1, ST2, ST3 respectively.

CONCLUSION

Blastocystis sp. was quite common in the study population, with a carrier rate corresponding to nearly one in every four individuals. The subtype distribution identified in the present study was largely identical to that reported from other studies in Iran, with ST3 being the most common.

Abstract P2-12-10: Psycho-spiritual therapy for improving the quality of life and spiritual well-being of women with breast cancer

Objective: Psychological distress and morbidity are common consequences of diagnosis and treatment of breast cancer and associated with poor quality of life (QOL). Among several approaches, spirituality has been shown to be significantly associated with improving the quality of life of these patients. The aim of this study was to assess the role of psycho-spiritual therapy intervention in improving the quality of life and spiritual well-being of patients with breast cancer.

Methods: This was a randomized controlled trial study which was conducted in the Breast Cancer Research Center, St. S. Al-Shohada hospital, Isfahan, Iran. Sixty-eight patients with breast cancer were randomized to either psycho-spiritual therapy intervention group or control group who received routine management and educational programs. Before and after 6 weeks of psycho-spiritual therapy sessions, the quality of life was evaluated using Cancer quality-of-life questionnaire (QLQ-C30) and its supplementary breast cancer questionnaire (QLQ-BR23) and Spiritual well-being was measured using the Functional Assessment of Chronic Illness Therapy Spiritual Well-being scale (FACIT-Sp12). Multivariate, repeated-measures ANOVA, T-test and Paired T-test were used for analysis using Predictive Analytic Soft Ware (PASW, version 18) for windows.

Results: In all sixty five patients actually completed the six-week intervention and were evaluated for the outcomes. The mean Global health status score/QOL reached from 44.37 (SD: 13.03) to 68.63 (SD: 10.86), (p < 0.001), (Cohen's d effect size: 2.16, 95% CI: 1.56–2.78). There was a statistically significant difference in all functional scales of QLQ-C30 (p < 0.05) as well as spiritual well-being after intervention. (p = 0.02)

Conclusions: The results of this trial showed that the psycho-spiritual therapy program can improve the spiritual well-being and QOL of women with breast cancer. This program, with its ease of implementation and home practice, could be adopted in comprehensive care programs for women with breast cancer.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-12-10.

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.

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.

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.

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.

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.