Ultra-thin polarization independent broadband terahertz metamaterial absorber

In this work, we present the design of a polarization independent broadband absorber in the terahertz (THz) frequency range using a metasurface resonator. The absorber comprises of three layers, of which, the top layer is made of a vanadium dioxide (VO₂) resonator with an electrical conductivity of σ = 200000 S/m; the bottom layer consists of a planar layer made of gold metal, and a dielectric layer is sandwiched between these two layers. The optimized absorber exhibits absorption greater than 90% from 2.54-5.54 THz. Thus, the corresponding bandwidth of the designed absorber is 3 THz. Further, the thermal tunable absorption and reflection spectra have been analyzed by varying the electrical conductivity of VO₂. The impact of the various geometrical parameters on the absorption characteristics has also been assessed. The physics of generation of broadband absorption of the proposed device has been explored using field analysis. Finally, the absorption characteristics of the unit cell has been studied for various incident and polarization angles.

Cerebral Venous Thrombosis in COVID-19: A New York Metropolitan Cohort Study

BACKGROUND AND PURPOSE

Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) infection is associated with hypercoagulability. We sought to evaluate the demographic and clinical characteristics of cerebral venous thrombosis among patients hospitalized for coronavirus disease 2019 (COVID-19) at 6 tertiary care centers in the New York City metropolitan area.

MATERIALS AND METHODS

We conducted a retrospective multicenter cohort study of 13,500 consecutive patients with COVID-19 who were hospitalized between March 1 and May 30, 2020.

RESULTS

Of 13,500 patients with COVID-19, twelve had imaging-proved cerebral venous thrombosis with an incidence of 8.8 per 10,000 during 3 months, which is considerably higher than the reported incidence of cerebral venous thrombosis in the general population of 5 per million annually. There was a male preponderance (8 men, 4 women) and an average age of 49 years (95% CI, 36-62 years; range, 17-95 years). Only 1 patient (8%) had a history of thromboembolic disease. Neurologic symptoms secondary to cerebral venous thrombosis occurred within 24 hours of the onset of the respiratory and constitutional symptoms in 58% of cases, and 75% had venous infarction, hemorrhage, or both on brain imaging. Management consisted of anticoagulation, endovascular thrombectomy, and surgical hematoma evacuation. The mortality rate was 25%.

CONCLUSIONS

Early evidence suggests a higher-than-expected frequency of cerebral venous thrombosis among patients hospitalized for COVID-19. Cerebral venous thrombosis should be included in the differential diagnosis of neurologic syndromes associated with SARS-CoV-2 infection.

Middle Meningeal Artery Embolization Using Combined Particle Embolization and n-BCA with the Dextrose 5% in Water Push Technique for Chronic Subdural Hematomas: A Prospective Safety and Feasibility Study

BACKGROUND AND PURPOSE

Embolization of the middle meningeal artery for treatment of refractory or recurrent chronic subdural hematomas has gained momentum during the past few years. Little has been reported on the use of the n-BCA liquid embolic system for middle meningeal artery embolization. We present the technical feasibility of using diluted n-BCA for middle meningeal artery embolization.

MATERIALS AND METHODS

We sought to examine the safety and technical feasibility of the diluted n-BCA liquid embolic system for middle meningeal artery embolization. Patients with chronic refractory or recurrent subdural hematomas were prospectively enrolled from September 2019 to June 2020. The primary outcome was the safety and technical feasibility of the use of diluted n-BCA for embolization of the middle meningeal artery. The secondary end point was the efficacy in reducing hematoma volume.

RESULTS

A total of 16 patients were prospectively enrolled. Concomitant burr-hole craniotomies were performed in 12 of the 16 patients. Two patients required an operation following middle meningeal artery embolization for persistent symptoms. The primary end point was met in 100% of cases in which there were no intra- or postprocedural complications. Distal penetration of the middle meningeal artery branches was achieved in all the enrolled cases. A 7-day post-middle meningeal artery embolization follow-up head CT demonstrated improvement (>50% reduction in subdural hematoma volume) in 9/15 (60%) patients, with 6/15 (40%) showing an unchanged or stable subdural hematoma. At day 21, available CT scans demonstrated substantial further improvement (>75% reduction in subdural hematoma volume).

CONCLUSIONS

Embolization of the middle meningeal artery using diluted n-BCA and ethiodized oil (1:6) is safe and feasible from a technical standpoint. The use of a dextrose 5% bolus improves distal penetration of the glue.

A case of mixed connective tissue disease with pseudo-pseudo Meigs' syndrome (PPMS)-like features

Pseudo-pseudo Meigs' syndrome (PPMS) has been reported to be a rare presentation of patients with systemic lupus erythematosus (SLE). However, such a presentation is not common in other forms of connective tissue disease. We presented a case of gross ascites, pleural effusion, and marked elevation of CA-125 level (PPMS-like features) that led to a diagnosis of MCTD. The patient responded to systemic steroid therapy.

ADAMTS13 modulates atherosclerotic plaque progression in mice via a VWF-dependent mechanism

BACKGROUND

ADAMTS13 reduces the adhesiveness of hyperactive ultra-large von Willebrand factor (ULVWF) multimers by cleaving them into smaller, less active multimers. Recently, we and others have demonstrated that ADAMTS13 reduces atherosclerosis in hypercholesteremic apolipoprotein E (ApoE-/-) deficient mice. It is not known whether ADAMTS13 modulates atherosclerosis directly or indirectly by cleaving ULVWF multimers.

OBJECTIVE

We generated triple knockout Adamts13-/-/Vwf-/-/ApoE-/- mice to determine whether ADAMTS13 modulates atherosclerosis through its proteolytic effects on VWF or other potential mechanisms.

METHODS

Female mice were fed a high-fat Western diet beginning at 6 weeks of age until they were sacrificed at 4 months. We compared the extent of atherosclerosis in the serial cross-sections of the aortic sinus using the Verhoeff-Van Gieson stain. Macrophage and neutrophil infiltration were quantified by immunohistochemistry. Under plain polarized light interstitial collagen content in the serial cross-sections of the aortic sinus was quantified using picrosirius red stain.

RESULTS

Deficiency of VWF in Adamts13-/-/ApoE-/- mice (Adamts13-/-/Vwf-/-/ApoE-/-) completely reversed exacerbated atherosclerosis (P < 0.05 vs. Adamts13-/-/ApoE-/- mice). The lesion size, macrophage and neutrophil infiltration in the aortic sinus of Adamts13-/-/Vwf-/-/ApoE-/- mice were significantly decreased compared with Adamts13-/-/ApoE-/- mice (P < 0.05), but similar to Vwf-/-/ApoE-/- mice. Additionally, interstitial collagen content in the aortic sinus of Adamts13-/-/Vwf-/-/ApoE-/- mice was significantly reduced compared with Adamts13-/-/ApoE-/- mice (P < 0.05), but similar to Vwf-/-/ApoE-/- mice. Total cholesterol and triglyceride levels were similar among groups.

CONCLUSIONS

ADAMTS13 modulates inflammatory plaque progression in hypercholesterolemic mice through a VWF-dependent mechanism. These findings provide further evidence on the pathophysiological role for the ADAMTS13/VWF axis in atherosclerosis.

Clinical characteristics of gout: a hospital case series

INTRODUCTION

Gout is an increasingly common medical problem. The traditional risk factors of male sex and high red meat or alcohol consumption have been joined with newer risks such as increased life expectancy, and the metabolic syndrome (hypertension, diabetes, dyslipidaemia, truncal obesity).

METHODS

This was a retrospective study to determine the epidemiology, clinical features, associated conditions as well as renal related conditions in existing gout patients followed-up in Rheumatology outpatient clinic, Hospital Tuanku Ja'afar, Seremban.

RESULTS

Over a three month period, we identified 54 gouty patients on our follow-up, the majority being male, Malay ethnicity, with the age of onset in the third and fourth decades of life. Commonly associated risk factors were hypertension, hyperlipidaemia and obesity. However, underlying history of diabetes mellitus, alcohol consumption, and family history were not commonly associated with gout in our group of patients. Half of our patients had at least two or more joints involvement. About half of the patients with tophaceous gout had renal impairment.

CONCLUSION

Our series of gout patients highlight the high prevalence of cardiovascular risk factors. The high prevalence of tophi and renal impairment is a cause for concern.

Association of CAG repeat loci on chromosome 22 with schizophrenia and bipolar disorder

Chromosome 22 has been implicated in schizophrenia and bipolar disorder in a number of linkage, association and cytogenetic studies. Recent evidence has also implicated CAG repeat tract expansion in these diseases. In order to explore the involvement of CAG repeats on chromosome 22 in these diseases, we have created an integrated map of all CAG repeats > or =5 on this chromosome together with microsatellite markers associated with these diseases using the recently completed nucleotide sequence of chromosome 22. Of the 52 CAG repeat loci identified in this manner, four of the longest repeat stretches in regions previously implicated by linkage analyses were chosen for further study. Three of the four repeat containing loci, were found in the coding region with the CAG repeats coding for glutamine and were expressed in the brain. All the loci studied showed varying degrees of polymorphism with one of the loci exhibiting two alleles of 7 and 8 CAG repeats. The 8-repeat allele at this locus was significantly overrepresented in both schizophrenia and bipolar patient groups when compared to ethnically matched controls, while alleles at the other three loci did not show any such difference. The repeat lies within a gene which shows homology to an androgen receptor related apoptosis protein in rat. We have also identified other candidate genes in the vicinity of this locus. Our results suggest that the repeats within this gene or other genes in the vicinity of this locus are likely to be implicated in bipolar disorder and schizophrenia.

Effects of intraseptal zolpidem and chlordiazepoxide on spatial working memory and high-affinity choline uptake in the hippocampus

Injection of GABA(A)/benzodiazepine receptor ligands into the medial septum (MS) alters the activity of cholinergic neurons that innervate the hippocampus and can produce bidirectional modulation of spatial memory. Recent evidence suggests that two subtypes of the GABA(A) receptor are differentially localized to either GABAergic (alpha(1)/beta(2)/gamma(2)) or cholinergic (alpha(3)/beta(3)/gamma(2)) neurons within the MS. The present studies characterized the dose-related behavioral and neurochemical effects of intraseptal infusions of two benzodiazepine (BDZ) agonists that appear to exhibit different profiles of pharmacological specificity for these receptor subtypes. Male Sprague-Dawley rats were cannulated and then artificial CSF, chlordiazepoxide (CDP: 8 or 12 microg), or zolpidem (4, 8, or 12 microg) was injected into the MS. Spatial working memory was assessed in a delay radial-arm maze task and the activity of cholinergic neurons in the MS was evaluated by high-affinity choline uptake (HA-ChU) in the hippocampus. Intraseptal injection of either CDP or zolpidem produced dose-related impairments in spatial working memory and decreases in hippocampal HAChU. Both BDZ agonists were found to produce retrograde memory deficits and a decrease in HAChU following the highest dose tested (12 microg). However, intraseptal injection of 8 microg of zolpidem produced a behavioral deficit comparable to the high dose of CDP, but did not alter HAChU within the HPC. Although the cholinergic component of the septohippocampal pathway has been shown to be important in modulating hippocampal physiology and spatial memory processes, data from the present experiments suggest that the GABAergic component may also play an important role in the behavioral functions of the septohippocampal pathway.

Reversible inactivation of the medial septum or nucleus basalis impairs working memory in rats: a dissociation of memory and performance

Lidocaine-induced inactivation of the medial septum immediately after training or prior to testing in a delay radial-arm maze task produced deficits in spatial working memory that reflected impaired acquisition of the task. Injection of lidocaine into the nucleus basalis magnocellularis produced a profile of behavioral changes that indicated that temporary inactivation of this structure impaired the behavioral expression of information already stored in working memory. This appears to reflect an impairment in processes that are required for performance (i.e., attention, motivation, sensorimotor function) of the task but not for retrieval of stored information. Site-specific inactivation of the basal forebrain should help to reveal the involvement of its component structures in different aspects of cognitive function.

Reversible inactivation of the medial septum or nucleus basalis impairs working memory in rats: a dissociation of memory and performance

Lidocaine-induced inactivation of the medial septum immediately after training or prior to testing in a delay radial-arm maze task produced deficits in spatial working memory that reflected impaired acquisition of the task. Injection of lidocaine into the nucleus basalis magnocellularis produced a profile of behavioral changes that indicated that temporary inactivation of this structure impaired the behavioral expression of information already stored in working memory. This appears to reflect an impairment in processes that are required for performance (i.e., attention, motivation, sensorimotor function) of the task but not for retrieval of stored information. Site-specific inactivation of the basal forebrain should help to reveal the involvement of its component structures in different aspects of cognitive function.

Ossification of the human stylohyoid ligament: a longitudinal study

We report the results of a longitudinal radiographic study of ossification of the stylohyoid ligament in a sample of patients treated for minor malocclusions. The results suggest that the vast majority of ossified sites in the stylohyoid ligaments are established during childhood and adolescence. The mean length of the sites shows a fairly rapid, linear increase with age until the end of adolescence; any further increase is nonlinear and occurs at a much slower rate. In young individuals the ossified sites were predominant in the superior part of the ligament. With increasing age ossified sites became prevalent also in other parts of the ligament. Ossified sites in the inferior part close to the hyoid bone were more common than previously reported.

Injection of IgG 192-saporin into the medial septum produces cholinergic hypofunction and dose-dependent working memory deficits

192-IgG saporin is an anti-neuronal immunotoxin that combines the 192 monoclonal antibody to the p75 neurotrophin receptor found on terminals and cell bodies of neurons in the cholinergic basal forebrain with the ribosome-inactivating protein saporin. Injection of 100, 237.5 or 375 ng of 192-saporin into the medial septum produced dose-related deficits in a variable-delay radial-arm maze task. 192-saporin decreased the number of correct choices and increased the number of errors in the delayed non-match to sample task. These deficits persisted throughout training and were most evident in the 375 ng group. The behavioral deficits were associated with dose-dependent decreases in pre-synaptic cholinergic parameters (ie., high affinity choline uptake) in the terminal fields of the medial septum (hippocampus, cingulate, entorhinal cortex). Choline uptake was not affected in the frontal cortex or the striatum; structures not innervated by the septum. There were no changes in regional concentrations of dopamine, serotonin, or their metabolites. Site-specific injection of IgG 192-saporin is a useful approach to explore the functions of the cholinergic basal forebrain and to model diseases of cholinergic hypofunction such as Alzheimer's disease.

The inhibition of platelet-activating factor-induced platelet activation by oleic acid is associated with a decrease in polyphosphoinositide metabolism

In an earlier study (Miwa, M., Hill, C., Kumar, R., Sugatani, J., Olson, M. S., and Hanahan, D. J. (1987) J. Biol. Chem. 262, 527-530) it was shown that an inhibitor of platelet-activating factor (PAF), a powerful endogenous mediator of platelet aggregation, was present in freeze-clamped perfused livers. Subsequently, we determined that this substance was a mixture of unsaturated free fatty acids (FFA). Among these FFA, oleic acid between 10 and 100 microM was found to be a potent inhibitor of PAF-induced platelet aggregation and serotonin secretion. Consequently, in order to understand the molecular mechanism of oleic acid action, we investigated the effects of this FFA on several biochemical events associated with platelet aggregation induced by PAF. The effect of oleic acid and/or PAF on the level of [32P]phosphatidylinositol 4-phosphate (PIP) and [32P]phosphatidylinositol 4,5-bisphosphate (PIP2) was examined by using platelets labeled with [32P]phosphate. Oleic acid induced a dose-dependent decrease in the levels of [32P]PIP and [32P]PIP2; a maximal decrease in [32P]PIP and [32P]PIP2 of approximately 50 and 25%, respectively, was observed within seconds after the addition of 20 microM oleic acid and persisted for at least 15 min. Oleic acid did not induce the formation of [3H]inositol phosphates in platelets prelabeled with [3H]inositol, suggesting that the decrease in [32P]PIP and [32P]PIP2 was not due to a stimulation of phospholipase C. In contrast to oleic acid, PAF induced a dose-dependent increase in the [32P]PIP level, reaching a maximum of approximately 200% 3 min after the addition of 1 nM PAF to the platelets. This increase in [32P]PIP was accompanied by platelet aggregation and secretion, and a close correlation was established between the [32P]PIP level and the degree of aggregation. Oleic acid and PAF, when added together to the platelets, interacted by affecting the level of [32P]PIP and [32P]PIP2 in an opposite way since the decrease in the level of [32P]PIP and [32P] PIP2 induced by oleic acid was partially reversed by an excess of PAF. The decrease in the levels of [32P] PIP and [32P]PIP2 caused by oleic acid was associated with an inhibition of platelet aggregation induced by PAF. Interestingly, oleic acid did not block [3H]PAF binding to platelets but inhibited the PAF-induced phosphorylation of platelet proteins of 20 kDa and 40 kDa. These results suggest that inhibition of the PAF response by oleic acid may be at one of the steps in the signal transduction.(ABSTRACT TRUNCATED AT 400 WORDS)