On the spectral response of a taiji-CROW device.

Physical systems with topological properties are robust against disorder. However, implementing them in integrated photonic devices is challenging because of the various fabrication imperfections and/or limitations that affect the spectral response of their building blocks. One such feature is strong backscattering due to the surface wall roughness of the waveguides, which can flip the propagating modes to counterpropagating modes and destroy the desired topological behavior. Here, we report a study on modeling, designing and testing an integrated photonic structure based on a sequence of two taiji microresonators coupled with a middle link microresonator (a taiji-CROW device, where CROW stands for coupled resonator optical waveguides). Our study provides design constraints to preserve the ideal operation of the structure by quantifying a minimum ratio between the coupling coefficients and the backscattering coefficients. This ratio is valuable to avoid surface roughness problems in designing topological integrated photonic devices based on arrays of microresonators.

How do presentation age and CSF opening pressure level affect long-term prognosis of pseudotumor cerebri syndrome in children? Experience of a single tertiary clinic.

BACKGROUND: Diagnosis and treatment of pseudotumor cerebri syndrome in children is still a challenge for clinicians. The aim of this study is to reveal the influence of presentation age and CSF opening pressure on long-term prognosis of pseudotumor cerebri and share our clinical data of the very young age (≤ 5-year) group. METHOD: This retrospective study includes the patients followed by the Marmara University Pediatric Neurology Clinic between years 2012 and 2020 diagnosed with definite, probable, or suggestive pseudotumor cerebri syndrome according to modified Friedman criteria. Patients were classified into three groups according to presentation age: group 1: ≤ 5 years old; group 2: 6-10 years; and group 3 > 10 years old. CSF opening pressure was also categorized into three groups as CSF < 20 cmH20; CSF 20-30 cmH20; and CSF > 30 cmH20. RESULTS: One hundred three patients, 62.1% female (n = 64), were enrolled in the study. Group 1 consisted of 16 patients (60% male), group 2 consisted of 30 patients (63.3% female), and group 3 consisted of 57 patients (66.7% female). The mean CSF opening pressure did not differ between the three age groups in our study (p > 0.05). Treatment response was not correlated with CSF opening pressure. Papilledema presence and level of CSF opening pressure were independent of age (p > 0.05). CONCLUSIONS: Age at presentation and CSF opening pressure at diagnosis are not any predictive factors that influence long-term prognosis of pseudotumor cerebri syndrome in children. Evaluation and follow-up of children should be done in personalized approach.

Differences between radiological findings of COVID-19 and non-COVID-19 infections in pediatric patients.

BACKGROUND: This study aimed to reveal the differences between coronavirus disease 2019 (COVID-19) infections and non-COVID-19 respiratory tract infections in pediatric patients. METHODS: Sixty pediatric patients admitted to the hospital between March 11, 2020 and April 15, 2020 with respiratory tract infections were evaluated retrospectively. Among them, 20 patients with reverse transcription-polymerase chain reaction (RT-PCR) tests and chest computed tomography (CT) examinations were included in the study. According to the RT-PCR test results, the patients were divided into the COVID-19 and non-COVID-19 groups. The clinical observations, laboratory results, and radiological features from the two groups were then compared. RESULTS: According to the RT-PCR test results, 12 patients were assigned to the COVID-19 group and 8 to the non-COVID-19 group. There were no significant differences between the two groups in terms of clinical or laboratory features. In terms of radiological features, the presence of bronchiectasis and peribronchial thickening was statistically significantly higher in the non-COVID-19 group (P = 0.010 and P = 0.010, respectively). CONCLUSIONS: In pediatric cases, diagnosing COVID-19 using radiological imaging methods plays an important role in determining the correct treatment approach by eliminating the possibility of other infections.

Relationship of the cycle threshold values of SARS-CoV-2 polymerase chain reaction and total severity score of computerized tomography in patients with COVID 19.

AIM: Studies analyzing viral load in COVID-19 patients and any data that compare viral load with chest computerized tomography (CT) severity are limited. This study aimed to evaluate the severity of chest CT in reverse transcriptase polymerase chain reaction (RT-PCR)-positive patients and factors associated with it. METHODOLOGY: SARS-CoV-2 RNA was extracted from nasopharyngeal swab samples by using Bio-speedy viral nucleic acid buffer. The RT-PCR tests were performed with primers and probes targeting the RdRp gene (Bioexen LTD, Turkey) and results were quantified as cycle threshold (Ct) values. Chest CT of SARS-CoV-2 RNA-positive patients (n = 730) in a period from 22 March to 20 May 2020 were evaluated. The total severity score (TSS) of chest CT ranged 0-20 and was calculated by summing up the degree of acute lung inflammation lesion involvement of each of the five lung lobes. RESULTS: Of the 284 patients who were hospitalized, 27 (9.5%) of them died. Of 236 (32.3%) patients, there were no findings on CT and 216 (91.5%) of them were outpatients (median age 35 years). TSS was significantly higher in hospitalized patients; 5.3% had severe changes. Ct values were lower among outpatients, indicating higher viral load. An inverse relation between viral load and TSS was detected in both groups. CT severity was related to age, and older patients had higher TSS (p < 0.01). CONCLUSION: Viral load was not a critical factor for hospitalization and mortality. Outpatients had considerable amounts of virus in their nasopharynx, which made them contagious to their contacts. Viral load is important in detecting early stages of COVID-19, to minimize potential spread, whereas chest CT can help identify cases requiring extensive medical care.

De novo myeloid sarcoma as a rare cause of small bowel obstruction: CT findings and histopathologic correlation.

Small bowel obstruction caused by myeloid sarcoma in a patient with any hematological abnormality is very rare. Myeloid sarcoma occurs most commonly in patients with acute myelogenous leukemia (AML) and less with other hematological disorders. A 57-year-old female presented with abdominal pain, nausea, vomiting, and constipation. Radiological studies showed concentric bowel thickening in distal ileum that caused nearly total luminal compromise and signs of obstruction in proximal ileal bowel loops. She underwent laparotomic surgery and ileal resection was done. Diagnosis of myeloid sarcoma was made by histopathological examination of surgical specimens. Bone marrow biopsy was done to rule out systemic acute myelogenous leukemia (AML). Results of bone marrow biopsy were within normal limits. Finally, the patient was diagnosed as de novo myeloid sarcoma. Although the histopathological examination makes a definitive diagnosis, imaging allows to locate the lesion, evaluate its complications, and guide for correct biopsy. Accurate diagnosis of myeloid sarcoma has important prognostic value as transformation to AML can happen without chemotherapy or stem cell transplantation.

Tuberculous peritonitis mimicking carcinomatosis peritonei: CT findings and histopathologic correlation.

The distinction between tuberculous peritonitis and peritoneal carcinomatosis is extremely difficult in patients with omental cake appearance on computed tomography and elevated CA-125 level. A 21-year-old female presented with abdominal distention, diarrhea, nausea, fever, weight loss, and night sweats. Serum CA-125 level was 563 U/L (normal range: <35 U/L) and other tumor markers were within normal range. Radiologic studies showed massive ascites, smooth minimal thickening and increased contrast enhancement of peritoneum, omental nodularities, hepatomegaly, and right pleural effusion. No underlying malignancy that could cause this condition was detected clinically and radiologically. Ultrasound-guided omental tru-cut biopsy was performed to exclude carcinomatosis peritonei. Histopathologic examination showed small-medium-sized granulomas with caseous necrosis. Molecular microbiology tests of biopsy specimens confirmed diagnosis of tuberculosis. In conclusion, tuberculous peritonitis should be in differential diagnosis of a patient with ascites, omental nodularities and elevated serum CA-125 levels.

Enlarging characteristics of four nickel-titanium rotary instrument systems under standardized conditions of operator-related variables.

We aimed to describe a computer-controlled testing device and evaluate the amount of material removed by using 4 Ni-Ti systems in simulated root canals. Eighty resin blocks were used. Hero 642, Hero Shaper, ProFile, and ProTaper rotary instruments were used to prepare the canals. Operator-related variables were standardized with the aforementioned device. Preoperative/postoperative photographic images of canals were measured at 11 levels from the apical tip. Statistical analyses were done with one-way analysis of variance, Tukey honestly significant difference, and Bonferroni tests. Significantly more material was removed by the ProTaper at 9 levels, ProFile at 6, and Hero 642 at 2 levels (P < .05); no significant difference was determined at 5 levels. Our results showed that ProTaper and ProFile removed significantly more material than Hero 642 and Hero Shaper at different levels of the curved root canals under controlled conditions of operator-related variables.