Characteristic Signal Pattern Research Articles

Highly Sensitive Detection of T790 M with a Three-Level Characteristic Current by Thymine-Hg(II)-Thymine in the α-Hemolysin Nanopore.

Sensitive detection of resistance mutation T790 M is of great significance for early diagnosis and prognostic monitoring of non-small-cell lung cancer (NSCLC). In this paper, we showed a highly sensitive detection strategy for T790 M using a three-level characteristic current signal pattern in an α-hemolysin nanopore. A probe was designed that formed a C-T mismatched base pair with wild-type/P and a T-T mismatched with the T790M/P. The T790M/P produced a unique three-level characteristic current signal in the presence of mercury ions(II): first, T790M-Hg2+-P entering the vestibule of α-HL under the transmembrane potential and overhang of probe occupying the β-barrel, then probe unzipping from the T790M/P, T790 M temporally residing inside the nanocavity due to the interaction with Hg(II), and finally T790 M passing through the β-barrel. The blocking current distribution was concentrated with a small relative standard deviation of about 3%, and the signal peaks of T790 M and wild-type can be completely separated with a high separation resolution of more than 2.5, which achieved the highly sensitive detection of T790 M down to 0.001 pM (confidence level P 95%) with a linear range from 0.001 pM to 1 nM in human serum samples. This highly sensitive recognition strategy enables the detection of low abundance T790 M and provides a method for prognostic monitoring in NSCLC patients.

Lighting up spin systems: enhancing characteristic 1H signal patterns of fluorinated molecules.

Fluorine is becoming increasingly prevalent in medicinal chemistry, both in drug molecules and in molecular probes. The presence of fluorine allows convenient monitoring of such molecules in complex environments by NMR spectroscopy. However, sensitivity is a persistent limitation of NMR, especially when molecules are present at low concentrations. Here, sensitivity issues with 1H NMR are mitigated by sharing 19F photochemically-induced dynamic nuclear polarisation with 1H nuclei. Unlike direct 1H enhancement, this method enhances 1H signals without significantly distorting multiplet intensities, and has the potential to enable the use of suitable molecules as low-concentration probes.

Tattoo Pigment Identification in Inks and Skin Biopsies of Adverse Reactions by Complementary Elemental and Molecular Bioimaging with Mass Spectral Library Matching.

Tattooing has become increasingly popular throughout society. Despite the recognized issue of adverse reactions in tattoos, regulations remain challenging with limited data available and a missing positive list. The diverse chemical properties of mostly insoluble inorganic and organic pigments pose an outstanding analytical challenge, which typically requires extensive sample preparation. Here, we present a multimodal bioimaging approach combining micro X-ray fluorescence (μXRF) and laser desorption ionization-mass spectrometry (LDI-MS) to detect the elemental and molecular composition in the same sample. The pigment structures directly absorb the laser energy, eliminating the need for matrix application. A computational data processing workflow clusters spatially resolved LDI-MS scans to merge redundant information into consensus spectra, which are then matched against new open mass spectral libraries of tattoo pigments. When applied to 13 tattoo inks and 68 skin samples from skin biopsies in adverse tattoo reactions, characteristic signal patterns of isotopes, ion adducts, and in-source fragments in LDI-MS1 scans yielded confident compound annotations across various pigment classes. Combined with μXRF, pigment annotations were achieved for all skin samples with 14 unique structures and 2 inorganic pigments, emphasizing the applicability to larger studies. The tattoo-specific spectral libraries and further information are available on the tattoo-analysis.github.io website.

Fusobacterium watanabei sp. nov. As additional species within the genus Fusobacerium, isolated from human clinical specimens

Eight spindle-shaped bacteria were isolated from clinical samples in Japan and investigated for their taxonomic position. Phylogenetic trees (based on 16S rRNA, rpoB, zinc protease, and gyrB gene sequence comparisons) showed distinct clustering of eight strains with the type strain of Fusobacterium nucleatum and its closely related species. In silico whole genome comparison analysis based on average nucleotide index based on BLAST (ANIb) and digital DNA-DNA hybridization (dDDH) data between our clinical isolates (PAGU 1795, PAGU 1796T, and PAGU 1797) and the type strain of the closely related species showed values of less than 92.4% and 49.5%, respectively. On the basis of its phylogenetic and genomic distinctiveness together with differential phenotypic properties and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) characteristic signal patterns, we propose Fusobacterium watanabei sp. nov., with the type strain PAGU 1796T (= GTC 21791T = CCUG 74246T).

Evaluation of Extra Axial Cerebellopontine Angle Tumours through MRI

Aim: This study aimed to evaluate the incidence of extra-axial cerebellopontine angle tumours and to characterize extra-axial cerebellopontine angle tumours.
 Methods: The study was carried out in Dhaka Medical College for the duration of 2 years from July 2016 to July 2018. All patients with clinical suspicion of CP angle tumours subjected 1.5 T MR imaging system. Total 30 patients were evaluated during this period.
 Results: Extra-axial CPA tumours accounts for 7-10% of brain tumours. Most common extraaxial CPA tumour is schwannoma (60%), followed by meningioma (27%), epidermoid (7%), arachnoid cysts (7%). 51-60 years is the most common age group involved. Schwannomas are common extra-axial CPA tumours which are enhancing round masses most commonly arise from the vestibular nerve and associated with enlargement of the internal auditory canal. Meningiomas are the second most common extra-axial CP angle tumours which oval or hemispheric lesions with a broad attachment to tentorium or petrous dura matter.
 Conclusion: MRI is the most sensitive noninvasive modality to characterize extra-axial CPA tumours. MRI identifies the location and extension of the lesions based on their characteristic signal and enhancement pattern on contrast.
 J Dhaka Medical College, Vol. 27, No.2, October, 2018, Page 104-107

Collecting Labels for Rare Anomalies via Direct Human Feedback—An Industrial Application Study

Many systems rely on the expertise from human operators, who have acquired their knowledge through practical experience over the course of many years. For the detection of anomalies in industrial settings, sensor units have been introduced to predict and classify such anomalous events, but these critically rely on annotated data for training. Lengthy data collection campaigns are needed, which tend to be combined with domain expert annotations of the data afterwards, resulting in costly and slow process. This work presents an alternative by studying live annotation of rare anomalous events in sensor streams in a real-world manufacturing setting by experienced human operators that can also observe the machinery itself. A prototype for visualization and in situ annotation of sensor signals is developed with embedded unsupervised anomaly detection algorithms to propose signals for annotation and which allows the operators to give feedback on the detection and classify anomalous events. This prototype allowed assembling a corpus of several weeks of sensor data measured in a real manufacturing surrounding and was annotated by domain experts as an evaluation basis for this study. The evaluation of live annotations reveals high user motivation after getting accustomed to the labeling prototype. After this initial period, clear anomalies with characteristic signal patterns are detected reliably in visualized envelope signals. More subtle signal deviations were less likely to be confirmed an anomaly due to either an insufficient visibility in envelope signals or the absence of characteristic signal patterns.

Glycogen distribution in mouse hippocampus.

The hippocampus is a limbic structure involved in the consolidation of episodic memory. In the recent decade, glycogenolysis in the rodent hippocampus has been shown critical for synaptic plasticity and memory formation. Astrocytes are the primary cells that store glycogen which is subject to degradation in hypoglycemic conditions. Focused microwave application to the brain halts metabolic activities, and therefore preserves brain glycogen. Immunohistochemistry against glycogen on focused microwave-assisted brain samples is suitable for both macroscopic and microscopic investigation of glycogen distribution. Glycogen immunohistochemistry in the hippocampus showed a characteristic punctate signal pattern that depended on hippocampal layers. In particular, the hilus is the most glycogen-rich subregion of the hippocampus. Moreover, large glycogen puncta (>0.5µm in diameter) observed in neuropil areas are organized in a patchy pattern consisting of puncta-rich and -poor astrocytes. These observations are discussed with respect to distinct hippocampal neural activity states observed in live animals.

Ex vivo tissue imaging for radiology-pathology correlation: a pilot study with a small bore 7-T MRI in a rare pigmented ganglioglioma exhibiting complex MR signal characteristics associated with melanin and hemosiderin.

.To advance magnetic resonance imaging (MRI) technologies further for in vivo tissue characterization with histopathologic validation, we investigated the feasibility of ex vivo tissue imaging of a surgically removed human brain tumor as a comprehensive approach for radiology–pathology correlation in histoanatomically identical fashion in a rare case of pigmented ganglioglioma with complex paramagnetic properties. Pieces of surgically removed ganglioglioma, containing melanin and hemosiderin pigments, were imaged with a small bore 7-T MRI scanner to obtain T1-, T2-, and T2*-weighted image and diffusion tensor imaging (DTI). Corresponding histopathological slides were prepared for routine hematoxylin and eosin stain and special stains for melanin and iron/hemosiderin to correlate with MRI signal characteristics. Furthermore, mean diffusivity (MD) maps were generated from DTI data and correlated with cellularity using image analysis. While the presence of melanin was difficult to interpret in in vivo MRI with certainty due to concomitant hemosiderin pigments and calcium depositions, ex vivo tissue imaging clearly demonstrated pieces of tissue exhibiting the characteristic MR signal pattern for melanin with pathologic confirmation in a histoanatomically identical location. There was also concordant correlation between MD and cellularity. Although it is still in an initial phase of development, ex vivo tissue imaging is a promising approach, which offers radiology–pathology correlation in a straightforward and comprehensive manner.

Automatic Identification of Interictal Epileptiform Discharges in Secondary Generalized Epilepsy.

Ictal epileptiform discharges (EDs) are characteristic signal patterns of scalp electroencephalogram (EEG) or intracranial EEG (iEEG) recorded from patients with epilepsy, which assist with the diagnosis and characterization of various types of epilepsy. The EEG signal, however, is often recorded from patients with epilepsy for a long period of time, and thus detection and identification of EDs have been a burden on medical doctors. This paper proposes a new method for automatic identification of two types of EDs, repeated sharp-waves (sharps), and runs of sharp-and-slow-waves (SSWs), which helps to pinpoint epileptogenic foci in secondary generalized epilepsy such as Lennox-Gastaut syndrome (LGS). In the experiments with iEEG data acquired from a patient with LGS, our proposed method detected EDs with an accuracy of 93.76% and classified three different signal patterns with a mean classification accuracy of 87.69%, which was significantly higher than that of a conventional wavelet-based method. Our study shows that it is possible to successfully detect and discriminate sharps and SSWs from background EEG activity using our proposed method.

Array-based sensing of purine derivatives with fluorescent dyes.

Natural and synthetic purine derivatives such as caffeine, theophylline, 6-mercaptopurine and 8-chlorotheophylline are important drugs. Due to the structural similarity of these compounds, it is intrinsically difficult to prepare chemosensors for their selective optical detection. Here, we describe a sensor array which can be used to differentiate pharmacologically important purine derivatives with good accuracy. The array is composed of four polysufonated fluorescent dyes, all of which can bind purines viaπ-stacking interactions. The complexation of the analytes results in partial quenching of the fluorescence. The fluorescence response of the four dyes provides a characteristic signal pattern, enabling the identification of thirteen purine derivatives at low millimolar concentration. Furthermore, it is possible to use the array for obtaining information about the quantity and purity of purine samples.

A case of nodular-type muscular sarcoidosis: findings of imaging, histopathology, and polymerase chain reaction.

We report a case of nodular-type muscular sarcoidosis with no systemic symptoms. Thallium-201 scintigraphy showed intense uptake in the muscular lesion mimicking malignant soft tissue tumor. Magnetic resonance imaging (MRI) demonstrated characteristic signal patterns of peripheral high intensity with central low intensity ("three stripes" pattern). Microscopy revealed sarcoid granuloma with typical histopathological characteristics. Propionibacterium acnes was detected on polymerase chain reaction analysis of the excised tissue.

Rare infraglottic lesions in magnetic resonance imaging.

SummaryBackgroundPrimary pathological laryngeal lesions occur rarely in infraglottic space. Modern possibilities of diagnostic imaging of infraglottic space include computed tomography (CT) and magnetic resonance (MR). Diagnostic imaging was performed in potential lesions in this area: inflammatory process – cicatrical pemphigoid, benign neoplastic process – chondroma, malignant neoplastic – squamous cell carcinoma.The aim of the paper is to present clinical and radiographical characteristics of selected lesions located in infraglottic space in MRI examination.Material/MethodsThree patients examined at the Department of Radiology and Diagnostic Imaging of University Hospital No. 1 in Lodz (SPZOZ USK nr 1) from 2010–2011 with a pathological mass in infraglottic space. Standard imaging protocol for MRI of the neck was used in all patients: field of 1.5 T, slice thickness 3 mm, the distance between the scans 10–20%, FOV – 3 mm, sequences: T1 (TR/TE 455/9, 7 ms, T2 (TR/TE 5300/67 ms), T1 + Gd-DTPA (contrast agent Gd-DTPA at 0.2 mmol/kg).Conclusions1. It is possible to determine characteristic signal pattern for rare lesions of the infraglottic space in MRI. 2. MRI is a valuable complementary modality for the diagnostics and differentiation of lesions in infraglottic space, the evaluation of their advancement and treatment planning.

Ordinal patterns in epileptic brains: Analysis of intracranial EEG and simultaneous EEG-fMRI

Epileptic seizures are associated with high behavioral stereotypy of the patients. In the EEG of epilepsy patients characteristic signal patterns can be found during and between seizures. Here we use ordinal patterns to analyze EEGs of epilepsy patients and quantify the degree of signal determinism. Besides relative signal redundancy and the fraction of forbidden patterns we introduce the fraction of under-represented patterns as a new measure. Using the logistic map, parameter scans are performed to explore the sensitivity of the measures to signal determinism. Thereafter, application is made to two types of EEGs recorded in two epilepsy patients. Intracranial EEG shows pronounced determinism peaks during seizures. Finally, we demonstrate that ordinal patterns may be useful for improving analysis of non-invasive simultaneous EEG-fMRI.

A new feature extraction method for odour classification

A new method for real time classification of volatile chemical substance traces is presented. The method is based on electrochemical signals of an array of semiconductor gas sensors. In these sensor signals characteristic patterns of different substances are hidden. There are non-linear correlative relationships between the measured sensor signals and the chemical substances which are treated using two methods derived from statistical learning theory (Support Vector Machine – SVM, Maximum Likelihood Estimation – MLE) for the detection of the substance characteristics in the sensor signals. A key criterion for the presented pattern recognition is a newly developed type of features, which is specially adapted to the low frequency signals of semiconductor sensors. The presented features are based on the evaluation of the range of the transient response in the sensor signals in the frequency domain. To derive the new features, both real measurement data and synthetic generated signals were used. In the experiments the focus was set on the creation of reproducible sensor signals to get characteristic signal patterns. Synthetic signals were derived from a Gaussian Plume Model. With the new features, training data sets were calculated using the classification methods SVM and MLE. With these training data sets new sensor measurements may be assigned to the substances which are to be sought. The advantage of the presented method is that no feature reduction is needed and no loss of information occurs in the learning process. The classification results based on the new features have been compared with the classification based on a conventional method for feature extraction. It was proved that the recognition rate of the substances used with the new feature type is higher. The substance classification is primarily limited by the sensitivity of the semiconductor sensors, because sufficiently large sensor signals must have been provided to obtain appropriate substance patterns. At the present stage of development the method presented is suitable for the classification of substance groups, such as nitro aromatics or alcohols, but not for specific substances.

Psammomatous melanotic schwannoma with cystic changes from old hemorrhages in the cervical spinal canal: a case report

Psammomatous melanotic schwannoma with cystic changes from old hemorrhages in the cervical spinal canal: a case report

MAGNETIC RESONANCE IMAGING FINDINGS IN 15 ACROMEGALIC CATS

Feline acromegaly is characterized by chronic excessive growth hormone secretion, most commonly caused by a functional pituitary adenoma. In this study, acromegaly was diagnosed in 15 cats on the basis of compatible clinical signs, laboratory, and magnetic resonance imaging (MRI) findings. MRI findings were reviewed retrospectively. Enlargement of the pituitary gland with suprasellar extension was present in all cats. No characteristic signal patterns were identified on T1-weighted and T2-weighted sequences. Contrast enhancement was nonuniform in all cats, as was suspected involvement of the adjacent hypothalamus. A mass effect on the cavernous sinus and third ventricle was present in 13 cats. Mild peritumoral edema was present in four cats, and moderate edema in one cat. Transtentorial herniation was present in one cat. Histopathology confirmed the presence of a pituitary adenoma in two cases. MRI is a useful modality to establish the diagnosis of acromegaly.

Standing magnetic resonance imaging detection of bone marrow oedema‐type signal pattern associated with subcarpal pain in 8 racehorses: A prospective study

The proximal metacarpal region is a common site of origin of lameness in the performance horse. A number of disease entities are recognised as causes of proximal metacarpal lameness but a definitive diagnosis is often elusive. Magnetic resonance imaging (MRI) is hypothesised to offer advantages over traditional imaging modalities in the investigation of proximal metacarpal pain. To describe clinical and imaging features of cases of lameness in racehorses arising from the proximal metacarpal region in which standing MRI identified 'bone marrow oedema-type' (BMO-type) signal patterns. Records for all horses undergoing standing MRI of the proximal metacarpus/distal carpus from September 2006 to December 2008 were reviewed. Cases underwent a standardised protocol for diagnostic analgesia, radiography and ultrasonography of the proximal metacarpus and distal carpus. Cases with proximal metacarpal lameness displaying a characteristic BMO-type signal pattern on MRI were identified and outcomes analysed. Eight cases were identified with characteristic MRI findings of extensive hyperintensity on T2* gradient echo and short tau inversion fast spin echo sequences and corresponding hypointensity on T1 gradient echo images within the palmaroproximal aspect of the third metacarpal bone. Follow-up information was available for all cases; at the time of writing 7/8 had returned to full work and were free from lameness. The BMO-type signal patterns visible on MR images in these cases may signal the existence of a previously under-diagnosed pathological process associated with proximal metacarpal lameness in racehorses. This finding is postulated to be associated with a stress reaction and possible prodromal stress fracture of the palmaroproximal metacarpus not appreciable radiographically or ultrasonographically. MRI of the proximal metacarpal region permits detection of pathological processes, which may elude conventional imaging and, therefore, has important therapeutic and prognostic implications in these cases.

SAW RFID-Tags for Mass-Sensitive Detection of Humidity and Vapors

One-port surface acoustic wave (SAW) devices with defined reflector patterns give characteristic signal patterns in the time domain making them identifiable and leading to so-called RFID-Tags. Each sensor responds with a burst of signals, their timed positions giving the identification code, while the amplitudes can be related to the analyte concentration. This paper presents the first combination of such a transducer with chemically sensitive layer materials. These include crosslinked polyvinyl alcohol for determining relative humidity and tert-butylcalix[4]arene for detecting solvent vapors coated on the free space between the reflectors. In going from the time domain to the frequency domain by Fourier transformation, changes in frequency and phase lead to sensor responses. Hence, it is possible to measure the concentration of tetrachloroethene in air down to 50 ppm, as well as 1% changes in relative humidity.

Distribution of the D15Z1 copy number polymorphism

Using fluorescent in situ hybridization (FISH) with the probe p15 (D15Z1), we investigated the distribution of the polymorphic 15p signal which has been reported to occur on acrocentric chromosomes in addition to chromosome 15. The short arm of chromosome 15 has a characteristic signal pattern when hybridized with the FISH probe D15Z1. However, the D15Z1 signal can occasionally be seen on the short arm of other acrocentric chromosomes. We studied the distribution of the D15Z1 probe in 1657 patients consisting both of individuals with a normal karyotype and those with a variety of chromosome abnormalities involving the acrocentric chromosomes. Our results show that one in six individuals, regardless of their patient ascertainment category or karyotypic status, had one or more additional D15Z1 signals, and that there were no significant differences in the distribution of extra signals among the patient groups.

Feature Extraction of a Strain-Gauge Signal Using Wavelets for Monitoring of a Tumbling Mill

Techniques that measure the force acting on a lifter bar, when it hits the charge inside a tumbling mill, have got an increased interest because of its direct physical relation to the behavior of the grinding charge. The possibility to combine it with discrete element modeling (DEM), which gives an opportunity to visualize the charge motion, opens new possibilities to understand the complex phenomena that takes place inside a grinding mill. In this work, a method for the measurement of the apparent filling level in a pilot ball mill, the Metso Continuous Charge Measurement system (CCM) has been used. The technique uses a strain gauge sensor, mounted on a flat steel spring, which is fitted into a recess underneath a lifter bar. Deflection of the lifter bar during every mill revolution will then give rise to a characteristic signal pattern depending on different operating conditions.In this work, which should be treated as an introduction, we show how the discrete wavelet transform can be used in multivariate calibration. It will be shown that by using the fast wavelet transform on individual signals as a pre-processing method in regression modeling on CCM measurements, good compression is achieved with almost no loss of information. The predictive ability and diagnostics of the data compressed regression model is almost the same as for the uncompressed.