Simple method for broadband amplification in a polarizing-maintained Yb fiber amplifier with a narrow bandpass filter.

We have demonstrated a simple method for achieving broadband amplification and short-pulse generation in a polarizing maintained (PM) Yb fiber amplifier with the implementation of a narrow bandpass filter (NBF). By using an NBF with a spectral bandwidth of 3.3 nm at a wavelength of 1036 nm before the PM Yb amplifier, the spectral bandwidth was extended by self-phase modulation (SPM) in the PM YDF amplifier. The recompressed pulse duration of 125 fs obtained with the NBF was nearly three times shorter than that (350 fs) achieved without the NBF, and therefore the peak intensity of 0.35 MW with the NBF was over two times greater in comparison with that (0.16 MW) obtained without the NBF. We believe that this simple method is useful for developing an all-fiber laser system for high-power short pulse generation.

Higher incidence of cervical spinal cord compression in amyotrophic lateral sclerosis: a single-institute cohort study.

BACKGROUND: Although the relationship between amyotrophic lateral sclerosis (ALS) and cervical spondylotic myelopathy (CSM) is important, data relating to CSM complications in ALS remain lacking. PURPOSE: We aimed to investigate and validate the spinal cord conditions of ALS patients. MATERIALS AND METHODS: We recruited all patients diagnosed with ALS, Parkinson's disease (PD), or chronic inflammatory demyelinating polyneuropathy (CIDP) who were admitted to our department from April 1, 2017, to March 31, 2020. We analyzed the cervical or thoracolumbar magnetic resonance imaging (MRI) scans of these 128 patients. Data relating to spondylosis, cord compression, spinal canal diameter, spinal cord diameter, and the closest distance between the cervical spinal canal and cord were validated using MRI. RESULTS: Of the 128 patients, 52 had ALS, 48 had PD, and 28 had CIDP. The proportions of both cervical spondylosis and cervical cord compression were highest in the ALS group compared with the other patient groups (p < 0.05). The proportion of cervical spondylosis in ALS patients reached 38.3%, and that of cervical cord compression reached 53.2%. The closest distance between the cervical spinal canal and cord was also significantly smaller in ALS patients compared with CIDP patients (p < 0.05). In contrast to the cervical cord findings, there were no significant differences in the thoracolumbar cord between ALS patients and the other patient groups. CONCLUSIONS: Of the three disease groups, the proportion of CSM was highest in ALS patients. Furthermore, cervical cord conditions were significantly more crowded in the ALS patients than in the other patient groups.

Coexisting of aortic arch atheroma and atrial fibrillation for short-term recurrence and poor functional outcome in acute stroke.

BACKGROUND AND PURPOSE: Multiple embolic sources are sometimes observed simultaneously in patients with embolic stroke. The present study investigated the effects of coexisting aortic arch atheroma ≥ 4 mm thick and atrial fibrillation (AF) on short-term stroke recurrence and functional outcome. METHODS: Transesophageal echocardiography (TEE) was performed in consecutive embolic stroke patients, and 395 patients were classified into 4 groups according to the presence of aortic arch atheroma ≥ 4 mm thick and AF: AF - /ARCH - group, AF + /ARCH - group, AF - /ARCH + group, and AF + /ARCH + group. In accordance with these 4 groups, we evaluated stroke recurrence and all-cause death for 3 months after stroke onset, and also evaluated the 3-month functional outcome using the modified Rankin scale (mRS). RESULTS: Among the 128 AF patients, 39.1% also had aortic arch atheroma ≥ 4 mm thick. Of the 395 enrolled cases, the AF + /ARCH + group showed the highest frequencies of stroke recurrence and all-cause death during 3 months after onset. On multivariate analysis, stroke recurrence or all-cause death during 3 months after onset was relatively more frequent in the AF + /ARCH + group than in the AF + /ARCH - group (OR, 2.34; 95% CI, 0.82-6.69; p = 0.11), but that was not statistically significant, and poor functional outcome (mRS score 3-6) at 3 months was significantly more frequent in the AF + /ARCH + group than in the AF + /ARCH - group (OR, 2.59; 95% CI, 1.08-6.24; p = 0.0339). CONCLUSIONS: Aortic arch atheroma concomitant with AF is not rare and appears associated with increased risks of stroke recurrence and poor functional outcome.

Real-time data on the prognosis of acute ischemic stroke patients in the Tochigi Clinical ObservatioNal registry for 1-year mortality of aCute ischEmic stRoke patieNt (T-CONCERN) study.

BACKGROUND: It is important to gauge mortality in real time following an ischemic stroke. However, there is limited in-hospital and post-discharge clinical data that focuses on the real-time prognosis of acute ischemic strokes. PURPOSE: To comprehensively analyze ischemic stroke mortality during a hospital stay and 1 year after the onset of a stroke. MATERIALS AND METHODS: Initially, 1514 consecutive acute ischemic stroke patients were admitted to our facility within 7 days after the onset of a stroke. Of these, 1116 patients who were successfully surveyed 1 year after onset were finally analyzed. Baseline, physical, laboratory, and stroke clinical data were recorded and analyzed. RESULTS: The proportion of deaths within 1 year was 14.5%, 4.9% without discharge was and 9.6% after discharge within 1 year. Cardioembolic ischemic strokes were responsible for nearly 50% of the deaths within 1 year while the remaining deaths were due to non-cardioembolic ischemic strokes. After 1 year, survival rate in the hospital decreased significantly, depending on whether the stroke was recurrent or if there was bleeding without a stroke. CONCLUSIONS: Our study reveals the real-time survival data 1 year after the onset of a stroke, in-hospital and post-discharge mortality rates, and several issues associated with the treatment of acute ischemic strokes.

Characteristics of aged ischemic stroke patients indicative of cardioembolism.

The treatment of ischemic stroke has recently witnessed dramatic developments. However, there are limited data on ischemic stroke characteristics in aged patients. As part of the South Tochigi Acute Ischemic Stroke Registry, we prospectively enrolled 636 consecutive acute ischemic stroke patients (within 7 days after the onset) who were ≥ 60 years of age and who were admitted to two independent institutes from April 1, 2016 to February 28, 2019. We analyzed three groups divided by age: early-aged (60-69 years), middle-aged (70-79 years), and oldest-aged (≥ 80 years). From the 636 subjects, 194 were early-aged, 215 were middle-aged, and 227 were oldest-aged. There were significant differences in the ischemic stroke subtypes in each aging group (p < 0.01). The proportion of cardioembolism was 22.2% in early-aged, 27.4% in middle-aged, and 41.4% in the oldest-aged patients. The proportion of patients with a modified Rankin Scale of 0-2 at 1 year after onset decreased to 42.2% in middle-aged and 17.8% in oldest-aged with cardioembolic ischemic stroke. The proportion of patients receiving anticoagulation therapy before admission was 25.6% (36.7% of atrial fibrillation [AF]) in early-aged, 39.0% (52.3% of AF) in middle-aged, and 18.1% (21.0% of AF) in oldest-aged patients (p < 0.001). Our study reports characteristics of clinical ischemic stroke in an aging population. The assessment of cardiogenic embolism is important for an aging population.

Impaired activity of daily living is a risk factor for high medical cost in patients of non-variceal upper gastrointestinal bleeding.

BACKGROUND: Non-variceal upper gastrointestinal bleeding (NVUGIB) is still a common and life-threatening disease, thus it would have a big impact on medical care cost. However, little is known about risk factors for increased medical care cost in NVUGIB patients. AIM: The purpose of the study was to clarify predictor of requiring high medical care cost in NVUGIB patients. Patients who underwent endoscopic hemostasis due to NVUGIB between April 2012 and March 2015 were included in this retrospective study. We analyzed the association between patients' background including activity of daily livings (ADL) and high medical care cost using logistic regression model. Medical care cost was calculated in reference to the "Diagnosis Procedure Combination" which is diagnosis-dominant case-mix system in Japan. The cutoff value of high medical care cost was defined as its first quartile. ADL was assessed according to Katz-6 score. We defined impaired ADL patient who revealed Katz-6 score more than 1. RESULTS: A total of 128 consecutive patients were included in this study. Median medical care cost was 5323 USD (IQR 3661-8172 USD). There were 13 patients (10%) in impaired ADL group. In univariate analysis, age and impaired ADL before admission revealed significant association with high cost. Of these, impaired ADL was an only independent risk factor [odds ratio 15.3 (95% CI 2.49-183)] in multivariate analysis. CONCLUSION: Impairment in ADL before admission was an independent predictor for high medical care cost with NVUGIB patients.

Catastrophic Secondary Infarctions with Onset Seizure Following Tissue Plasminogen Activator Therapy.

Fatalities following intravenous recombinant tissue-type plasminogen activator therapy have been reported. Major fatal complications following intravenous recombinant tissue-type plasminogen activator therapy include intracranial hemorrhage, aortic dissection, and extracranial bleeding. However, the possibility that intravenous recombinant tissue-type plasminogen activator therapy itself paradoxically induces synchronized multiple cerebral novel infarctions has never been considered. We herein report the first case of bilateral internal carotid artery infarction with onset seizure following intravenous recombinant tissue-type plasminogen activator therapy for a vertebral-basilar artery infarction. A 75-year-old man was transferred to our hospital and diagnosed with acute ischemic stroke in the basilar artery. His National Institute of Health Stroke Scale score was 4. The intravenous recombinant tissue-type plasminogen activator therapy was initiated 234 minutes after stroke onset because no contraindications were present. Almost 2 hours after the intravenous recombinant tissue-type plasminogen activator therapy, the patient suddenly fell into a deep coma with generalized convulsions. A huge secondary infarction was found in the bilateral anterior circulation territories, and he died 7 days after stroke onset. This case alerts clinicians to the possibility of synchronized multiple cerebral infarctions following intravenous recombinant tissue-type plasminogen activator therapy as a dangerous complication in patients with multiple severe stenoses in the cerebral arteries.

Repetitive Episodic Isolated Vertigo in a Patient with Cerebellar Infarction.

Isolated vertigo is an important symptom of posterior circulation stroke. It has been reported that 11.3% of patients with isolated vertigo have a stroke and that most lesions are located in the cerebellum, particularly in the posterior inferior cerebellar artery. We report the case of a 63-year-old man with multiple atherosclerotic risk factors and atrial fibrillation who showed repeated episodes of isolated vertigo. His repeated vertigo was short-lasting and was often triggered by body position, mimicking benign paroxysmal positional vertigo. Cranial computed tomography on the third hospital day showed left cerebellar infarction within the territory of the posterior inferior cerebellar artery. The vertigo was ameliorated on the fifth hospital day and warfarin was prescribed for secondary prevention. Clinicians should pay special attention to cases in which a patient presents isolated vertigo, even if it shows transient recurrence or is triggered by a positional change, especially in patients with multiple cerebrovascular risk factors.

Spectral periodicity in soliton explosions on a broadband mode-locked Yb fiber laser using time-stretch spectroscopy.

Experimentally, we demonstrate, to the best of our knowledge, the first observation of periodic spectrum changing via soliton explosion in a passively mode-locked fiber laser by a nonlinear polarization evolution. Using time stretch to capture 7220 consecutive single-shot spectra over a 100 µs time window in real time, the soliton explosions appear in a transition between two different mode-locking states. Simultaneous measurements of spectrum and pulse energy at three different output points in the laser cavity show that the soliton explosion's dynamics are related to residual dispersion. This study improves the understanding of pulse formation and evolution in the unstable mode-locking regime of lasers.

The Role of History of Gastro-Duodenal Ulcer in Patients with Upper Gastrointestinal Bleeding.

BACKGROUND: Some scoring systems have been introduced to predict the need for performing urgent endoscopy in patients with upper gastrointestinal bleeding (UGIB). However, in an emergency situation, this intervention is insufficient and cannot easily provide the required treatment. AIM: To identify new risk factors that can predict the need for endoscopic intervention (EI) in UGIB patients. METHODS: This is a retrospective cross-sectional study. Patients with UGIB admitted from April 2011 to August 2014 were included. The proportion of cases requiring EI and clinical factors (age, gender, antiplatelet/anticoagulant therapy, history of gastro-duodenal ulcer (GDU), systolic blood pressure, heart rate, hemoglobin, mean corpuscular volume, blood urea nitrogen-creatinine ratio (BUN/Cr ratio), prothrombin time-international normalized ratio, and Glasgow-Blatchford Score (GBS) were analyzed using logistic regression models. RESULT: Of 378 patients who were included in this study, 180 were found to be with GDU. The proportion of cases requiring EI was significantly higher in those with GDU than in other causes except variceal bleeding (53.5 vs. 37.0%, p < 0.01). Multivariate analysis revealed that a history of GDU was an independent risk factor (OR 1.78, 95% CI 1.06-3.00) in addition to BUN/Cr ratio (OR 1.02, 95% CI 1.00-1.03) and GBS (OR 1.19, 95% CI 1.08-1.33). CONCLUSION: A history of GDU was an independent risk factor for predicting the need for EI in UGIB in addition to BUN/Cr ratio and GBS.

Initial Management of Colonic Diverticular Bleeding: Observational Study.

BACKGROUND/AIMS: Although colonic diverticular bleeding (CDB) often ceases spontaneously, re-bleeding occurs in about 30%. Bleeding diverticulum can be treated directly by endoscopic hemostasis; however, it is difficult to perform colonoscopy in all cases with limited medical resource and certain risks. The aim of this study was to clarify who should undergo colonoscopy as well as appropriate methods of initial management in CDB patients. METHODS: A total of 285 patients who were diagnosed as CDB and underwent colonoscopy from March 2004 to October 2015 were retrospectively analyzed. First, the association between re-bleeding and various factors including patients' background and initial management were analyzed. Second, the examination conditions that influenced bleeding point identification were analyzed. RESULTS: Of 285 patients, 187 were men and 98 were women. Median age was 75 years, and the median observation period was 17.5 months. Re-bleeding was observed in 79 patients (28%). A history of CDB (OR 2.1, p = 0.0090) and chronic kidney disease (CKD; OR 2.3, p = 0.035) were risk factors, and bleeding point identification (OR 0.20, p = 0.0037) was a preventive factor for re-bleeding. Bleeding point identification significantly reduced approximately 80% of re-bleeding. Furthermore, extravasation on CT (OR 3.7, p = 0.031) and urgent colonoscopy (OR 5.3, p < 0.001) were predictors for identification of bleeding point. Compared to bleeding point identification of 11% in all patients who underwent colonoscopy, identification rate in those who had extravasation on CT and underwent urgent colonoscopy was as high as 70%. CONCLUSIONS: Contrast-enhanced CT upon arrival is suggested, and patients with extravasation on CT would be good candidates for urgent colonoscopy, as well as patients who have a history of CDB and CKD.

Successful Tissue Plasminogen Activator for a Patient with Stroke After Stanford Type A Aortic Dissection Treatment.

Some stroke patients with the acute aortic dissection receiving thrombolysis treatment resulted in fatalities. Thus, the concurrent acute aortic dissection is the contraindication for the intravenous recombinant tissue-type plasminogen activator. However, the safety and the effectiveness of the intravenous recombinant tissue-type plasminogen activator therapy are not known in patients with stroke some days after acute aortic dissection treatment. Here, we first report a case of a man with a cardioembolism due to the nonvalvular atrial fibrillation, who received the intravenous recombinant tissue-type plasminogen activator therapy 117 days after the traumatic Stanford type A acute aortic dissection operation. Without the intravenous recombinant tissue-type plasminogen activator therapy, the prognosis was expected to be miserable. However, the outcome was good with no complication owing to the intravenous recombinant tissue-type plasminogen activator therapy. Our case suggests the effectiveness and the safety of the intravenous recombinant tissue-type plasminogen activator therapy to the ischemic stroke some days after acute aortic dissection treatment.

Tissue Plasminogen Activator to Treat a Stroke after Foam Sclerotherapy in a Woman with a Patent Foramen Ovale.

Although foam sclerotherapy to varicose veins is now a popular treatment because of its high efficacy and safety, some neurologic complications have recently been reported. Presently, the effectiveness and safety of intravenous recombinant tissue-type plasminogen activator therapy to stroke following foam sclerotherapy remain unclear. Here, we report the case of a 68-year-old woman whose ischemic symptoms following foam sclerotherapy were treated by intravenous recombinant tissue-type plasminogen activator. After she was admitted, the venous thrombosis in her right soleus vein and a patent foramen ovale causing the right-to-left shunt were revealed. Thus, we diagnosed the ischemic symptoms were due to paradoxical embolism following foam sclerotherapy. After intravenous recombinant tissue-type plasminogen activator therapy, there was no complication and the outcome was good. Our case suggests the effectiveness and the safety of intravenous recombinant tissue-type plasminogen activator therapy to paradoxical embolism following foam sclerotherapy.

Vertical Gaze Palsy Caused by Selective Unilateral Rostral Midbrain Infarction.

Vertical gaze palsy is rarely a neurological symptom, although it has been observed in some cases. Here, we report the case of a patient presenting with complete upward and downward gaze palsy. In this case, a small lesion in the left rostral midbrain was observed on diffusion-weighted magnetic resonance (MR) images, and the lesion was considered to cause the ocular symptom. We consider that vertical gaze palsy is an important clue to an accurate topical diagnosis of a brain lesion.

Prevalence of Gastric Non-Helicobacter pylori-Helicobacters in Japanese Patients with Gastric Disease.

BACKGROUND: Non-Helicobacter pylori-helicobacters (NHPH) compose a group of gram negative zoonotic bacteria that may induce in humans gastric diseases including gastritis, gastroduodenal ulcer and MALT lymphoma. Their prevalence in the general population has previously been reported to 0.1-6.2%, although such reports still remain less in number. AIMS: This study aimed at estimating the prevalence of gastric NHPH in Japanese people, and further aimed at linking this to different gastric diseases and co-infection with H. pylori. METHODS: Endoscopically obtained biopsy samples from 280 Japanese patients with various gastric diseases were collected. Samples were analyzed by immunohistochemistry and by species-specific PCR for detection of gastric helicobacters. RESULTS: The total prevalence of gastric NHPH among 280 Japanese patients was 6.1%, and the prevalence of H. pylori was 65.7%. There was no significant difference in prevalence of either NHPH or H. pylori when infected with H. pylori or NHPH, respectively. NHPH infection was found to be the highest in patients with gastric MALT lymphoma and duodenal ulcer, the former being independent of co-infection with H. pylori and the latter being dependent. CONCLUSIONS: This study reports a total prevalence of 6.1% of gastric NHPH in Japanese patients, and further highlights gastric MALT lymphoma and duodenal ulcer (when co-infected with H. pylori) as important related diseases.

Vertical asymmetry of lamina cribrosa tilt angles using wide bandwidth, femtosecond mode-locked laser OCT; effect of myopia and glaucoma.

PURPOSE: Morphological features of the lamina cribrosa (LC) and optic disc may be important in the pathogenesis of glaucoma and myopic neuropathy. We therefore performed a cross-sectional study of patients with glaucoma and myopic neuropathy to evaluate vertical asymmetry of LC tilt angles (LCTAs) from Bruch's membrane opening (BMO). MATERIAL AND METHODS: Forty-six control eyes and 35 primary open-angle glaucoma (POAG) eyes were included. A raster scanning protocol with 300 single B-scans (without averaging) were obtained using optical coherence tomography with a wide-bandwidth, femtosecond mode-locked (ML) laser. Superior temporal to inferior nasal (ST) direction and inferior temporal to superior nasal (IT) direction (±45° rotation with a horizontal line) lines were drawn, and the angle between the inner edge of the BMO plane and the best fitting line for the anterior LC plane was measured as the LCTA. The generalized estimating equation was used to analyze the eye-derived data. RESULTS: Although no significant differences in either ST-LTCAs or IT-LTCAs were observed between the glaucoma group and non-glaucoma group, the IT-LCTAs were found to be significantly greater than the ST-LCTA in both the glaucoma and non-glaucoma groups (P < 0.001). After adjustment for other potential confounding factors by multivariate analysis, greater refractive errors were significantly correlated with IT-LCTAs. CONCLUSIONS: Vertical asymmetry of the LC tilting from the BMO plane exists in both normal and POAG eyes, and correlates with the degree of myopia.

Application of mid-infrared pulses for quasi-phase-matching of high-order harmonics in silver plasma.

We demonstrate the quasi-phase-matching of a group of harmonics generated in Ag multi-jet plasma using tunable pulses in the region of 1160 - 1540 nm and their second harmonic emission. The numerical treatment of this effect includes microscopic description of the harmonic generation, propagation of the pump pulse, and the propagation of the generated harmonics. We obtained more than 30-fold growth of harmonics at the conditions of quasi-phase-matching in the region of 35 nm using eight-jet plasma compared with the case of imperforated plasma.

Two-color high-harmonic generation in plasmas: efficiency dependence on the generating particle properties.

The high-order harmonic generation (HHG) in silver, gold, and zinc plasma plumes irradiated by orthogonally polarized two-color field is studied theoretically and experimentally. We find an increase of the HHG efficiency in comparison with the single-color case, which essentially depends on the plasma species and harmonic order. An increase of more than an order of magnitude is observed for silver plasma, whereas for gold and zinc it is lower; these results are reproduced in our calculations that include both propagation and microscopic response studies. We show that the widely used theoretical approach assuming the 1s ground state of the generating particle fails to reproduce the experimental results; the agreement is achieved in our theory using the actual quantum numbers of the outer electron of the generating particles. Moreover, our theoretical studies highlight the redistribution of the electronic density in the continuum wave packet as an important aspect of the HHG enhancement in the two-color orthogonally polarized fields with comparable intensities: in the single-color field the electronic trajectories with almost zero return energy are the most populated ones; in the two-color case the total field maximum can be shifted in time so that the trajectories with high return energies (in particular, the cut-off trajectory) become the most populated ones.

Augmented Renal Clearance in Pediatric Patients With Febrile Neutropenia Associated With Vancomycin Clearance.

BACKGROUND: Vancomycin (VCM) dosage optimization in the early stages of therapy is required to achieve target trough serum concentrations, particularly in critically ill patients. Augmented renal clearance (ARC), commonly characterized by an enhanced renal clearance, has been associated with subtherapeutic concentrations of antibiotics. The aim of this study was to investigate the risk factors including febrile neutropenia for both ARC and VCM clearance in Japanese pediatric patients. METHODS: A total of 109 pediatric patients with normal renal function were included in this observational study. From VCM serum concentrations, individual VCM clearance was estimated by the Bayesian method using a 1-compartment model. Patients were classified on the basis of the presence of febrile neutropenia, cancer, trauma, systemic inflammatory response syndrome, and surgical operation. Risk factors for ARC, as defined by estimated glomerular filtration rate (eGFR) above median value (≥160 mL·min·1.73 m), were evaluated. RESULTS: Febrile neutropenia was only an independent risk factor for ARC (odds ratio, 5.86; 95% confidence interval, 1.98-21.66, P = 0.0030), which was the result of a stepwise multivariate logistic regression analysis. Although univariate analysis demonstrated a significant association of febrile neutropenia with VCM clearance, the significant independent factors of VCM clearance were age and eGFR but not febrile neutropenia, as estimated by the stepwise multivariate linear regression analysis. CONCLUSIONS: This observational study concluded that febrile neutropenia, a significant risk factor for ARC, indirectly influenced VCM clearance towing to an elevated eGFR. Cancer, trauma, systemic inflammatory response syndrome, and surgical operation were not significantly associated with ARC; however, more studies are needed to validate this observation. Adjustment of the initial dosage of VCM is required for achieving optimal therapeutic concentrations in pediatric patients with febrile neutropenia.

[The effects of instruction about strategies for efficient calculation].

Calculation problems such as "12x7÷3" can be solved rapidly and easily by using certain techniques; we call these problems "efficient calculation problems." However, it has been pointed out that many students do not always solve them efficiently. In the present study, we examined the effects of an intervention on 35 seventh grade students (23 males, 12 females). The students were instructed to use an overview strategy that stated, "Think carefully about the whole expression", and were then taught three sub-strategies. The results showed that students solved similar problems efficiently after the intervention and the effects were preserved for five months.