Effects of a parasympathetic blocker on the heart rate of loggerhead sea turtles during voluntary diving.

Diving bradycardia is a reduction in the heart rate mediated by the parasympathetic system during diving. Although diving bradycardia is pronounced in aquatic mammals and birds, the existence of this response in aquatic reptiles, including sea turtles, remains under debate. Using the parasympathetic blocker atropine, we evaluated the involvement of the parasympathetic nervous system in heart rate reduction of loggerhead sea turtles (Caretta caretta) during voluntary diving in tanks. The heart rate of the control group dropped by 40-60% from the pre-dive value at the onset of diving; however, administration of atropine significantly inhibited heart rate reduction (P<0.001). Our results indicate that, similar to mammals and birds, the heart rate reduction in sea turtles while diving is primarily mediated by the parasympathetic nervous system. In conclusion, we suggest that diving bradycardia exists not only in aquatic mammals and birds but also in aquatic reptiles.

Covid-19-derived plastic debris contaminating marine ecosystem: Alert from a sea turtle.

On 10 August 2021, a face mask (14 cm × 9 cm) was found in the feces of a juvenile green turtle, by-caught alive in a set net off the northeast coast of Japan. Although sea turtles have been monitored in this region over the last 15 years (n = 76), face masks had never been found before the Covid-19 pandemic and this is the first detection. Fourier-transform infrared spectroscopy identified the mask as polypropylene. Estrogenic active benzotriazole-type UV stabilizers such as UV329 were detected in commercially available polypropylene face masks. Exposure of marine organisms ingesting plastics to endocrine-disrupting chemicals and physical injury are of concern. This study indicates that changes in human life in the pandemic are beginning to affect marine life. Precautionary actions including establishment of appropriate waste management of personal protective equipment and use of safe additives are urgently needed.

A non-invasive system to measure heart rate in hard-shelled sea turtles: potential for field applications.

To measure the heart rate of unrestrained sea turtles, it has been believed that a probe must be inserted inside the body owing to the presence of the shell. However, inserting the probe is invasive and difficult to apply to animals in the field. Here, we have developed a non-invasive heart rate measurement method for some species of sea turtles. In our approach, an electrocardiogram (ECG) was performed using an animal-borne ECG recorder and two electrodes-which were electrically insulated from seawater-pasted on the carapace. Based on the measured ECG, the heartbeat signals were identified with an algorithm using a band-pass filter. We implemented this algorithm in a user-friendly program package, ECGtoHR. In experiments conducted in a water tank and in a lagoon, we successfully measured the heart rate of loggerhead, olive ridley and black turtles, but not green and hawksbill turtles. The average heart rate of turtles when resting underwater was 6.2 ± 1.9 beats min-1 and that when moving at the surface was 14.0 ± 2.4 beats min-1. Our approach is particularly suitable for endangered species such as sea turtles, and has the potential to be extended to a variety of other free-ranging species. This article is part of the theme issue 'Measuring physiology in free-living animals (Part I)'.

Analysis of why sea turtles swim slowly: a metabolic and mechanical approach.

Animals with high resting metabolic rates and low drag coefficients typically have fast optimal swim speeds in order to minimise energy costs per unit travel distance. The cruising swim speeds of sea turtles (0.5-0.6 m s-1) are slower than those of seabirds and marine mammals (1-2 m s-1). This study measured the resting metabolic rates and drag coefficients of sea turtles to answer two questions: (1) do turtles swim at the optimal swim speed?; and (2) what factors control the optimal swim speed of turtles? The resting metabolic rates of 13 loggerhead and 12 green turtles were measured; then, the cruising swim speeds of 15 loggerhead and 9 green turtles were measured and their drag coefficients were estimated under natural conditions. The measured cruising swim speeds (0.27-0.50 m s-1) agreed with predicted optimal swim speeds (0.19-0.32 m s-1). The resting metabolic rates of turtles were approximately one-twentieth those of penguins, and the products of the drag coefficient and frontal area of turtles were 8.6 times higher than those of penguins. Therefore, our results suggest that both low resting metabolic rate and high drag coefficient of turtles determine their slow cruising speed.

High resting metabolic rates with low thermal dependence induce active dives in overwintering Pacific juvenile loggerhead turtles.

The metabolic rate and activity of sea turtles generally decreases with decreasing seasonal ambient temperature. Juvenile loggerhead turtles in the Mediterranean Sea made prolonged inactive dives (>400 min), indicating a state of dormancy during the cold winter period. However, seasonal differences in dive duration were not detected in juvenile loggerheads in the western North Pacific, even though the ambient water temperature changed by more than 10°C. Thus, metabolic states might differ among populations, explaining differences in the diving behaviour of juveniles during winter. Here, we tested the hypothesis that the active overwintering behaviour of juvenile loggerheads in the western North Pacific is driven by a high resting metabolic rate (RMR) with low thermal dependence. The RMR of juveniles in the western North Pacific (N=13) was 1.4-5.7 times higher (Q10=1.8) than that of juveniles in the Mediterranean Sea (Q10=5.4). To validate the high RMR values in the western North Pacific, the difference between core body temperature and ambient water temperature (ΔTb) was estimated from measured RMR and was compared with measured ΔTb The measured and estimated ΔTb matched each other. In addition, most of the dives conducted by the turtles in the western North Pacific were within the calculated aerobic dive limit (cADL) expected from the measured metabolic rate. Our results indicate that high RMR with low thermal dependence induces active diving during the overwintering periods of juvenile loggerheads in the western North Pacific, supporting the suggestion that metabolic states differ among populations.

Fatal Familial Insomnia Initially Developing Parkinsonism Mimicking Dementia with Lewy Bodies.

We report a rare case of fatal familial insomnia in a 58-year-old man who initially developed parkinsonism, secondary dementia, and visual hallucinations that were suspected to be due to dementia with Lewy bodies. We evaluated the function of the striatum via dopamine transporter single-photon emission computed tomography (DAT SPECT) using 123I-ioflupane and found marked presynaptic dopamine dysfunction in the bilateral striatum. This is the first reported case in which the initial symptom of fatal familial insomnia was parkinsonism and in which the dopamine transporter function was evaluated by DAT SPECT.

The Clinical Features of Ischemic Stroke Patients for Whom Smoking Was Considered the Sole Risk Factor for Ischemic Stroke.

Objective The purpose of this study was to clarify the clinical features of ischemic patients for whom cigarette smoking was the sole risk factor for ischemic stroke. Methods Among the 1,329 patients (male, n=833; female, n=496) with acute ischemic stroke who were admitted to our hospital between April 2005 and September 2016, 346 (26%) were smokers [male, n=308 (36.9%); female, 38 (7.6%)]. In 42 (3.1%; male, n=41; female, n=1) cases, cigarette smoking was considered to be the sole risk factor for ischemic stroke. Data regarding gender, age, the clinical type of ischemic stroke, the National Institutes of Health Stroke Scale (NIHSS) score at the admission, the modified Rankin scale (mRS) scores before the onset and at discharge, the progression of symptoms, and the recurrence of infarction were investigated. Results The mean age of the 42 patients was 63.2±12.4 years (range, 26-86 years). The clinical types of ischemic stroke included atherothrombosis (n=19), lacunar (n=17), other type (n=2) and undetermined type (n=4). The median NIHSS score at the time of admission for ischemic stroke was 2 (interquartile range: IQR 1-4.25). The median mRS scores before the onset and at the discharge were 0 (IQR 0-0) and 1 (IQR 0-2), respectively. One patient had symptoms of progression; no patients had recurrence of infarction. Conclusion Our findings suggest that cigarette smoking alone may induce ischemic stroke; moreover, patients for whom smoking was the sole risk factor for ischemic stroke showed milder symptoms in comparison to patients with other risk factors; however, ischemic stroke was induced from youth. Since cigarette smoking has detrimental effects on the central nervous system, we suggest that people be encouraged to quit smoking in order to maintain good health.

Isolated Hypoglossal Paralysis Caused by Ischemic Infarction in the Centrum Semiovale.

In the present report, we discuss the case of a 66-year-old woman with isolated unilateral hypoglossal paralysis due to cerebral infarction in the centrum semiovale. To date, it has hardly been discussed where the corticolingual tract passes through in the centrum semiovale. Brain magnetic resonance imaging revealed a small ischemic infarction in the contralateral centrum semiovale. We could demonstrate a route of the corticolingual tract.

A case of urinary retention in the early stages of herpes simplex virus type-1 encephalitis.

A 70-year-old man developed urinary retention in the early stages of herpes simplex virus (HSV) type-1 encephalitis. A nerve conduction study suggested latent myeloradiculitis. This is the first report of human herpes simplex virus-1 encephalitis followed by urinary retention at early stage from the onset like the Elsberg syndrome. Although relatively few similar cases have been reported, we consider that urinary retention is common in HSV-1 encephalitis, in which disturbances of consciousness usually require bladder catheterization from the onset. We further emphasize that urinary retention may occasionally occur in early stages of HSV-1 encephalitis, with a significant possibility of recovery.

Functional Outcomes of Decompressive Craniectomy in Patients with Malignant Middle Cerebral Artery Infarction and Their Association with Preoperative Thalamus Deformation: An Analysis of 12 Patients.

Objective Decompressive craniectomy (DC) in patients with malignant middle cerebral artery (MCA) infarction is known to decrease the mortality rate. However, the functional outcomes (communication and oral intake) of this procedure remain unclear. Most patients with malignant MCA infarction exhibit a loss of consciousness, which may be principally governed by the thalamus. We herein investigated the functional outcomes of DC at 90 days after the onset of malignant MCA infarction and their association with preoperative thalamus deformation, which can occur due to pressure and edema. Methods Twelve of 2,692 patients with acute cerebral infarction were diagnosed with malignant MCA infarction and underwent DC. We evaluated preoperative thalamus damage using brain computed tomography and its association with communication and oral intake abilities and the modified Rankin Scale (mRS) and Barthel index scores at 90 days after stroke onset. Results The mRS score at 90 days was 0-4 in five patients. Seven patients could communicate immediately after surgery, while five could do so by 90 days. Five patients were able to resume the oral intake of food at 90 days. All patients with preoperative thalamus deformation showed a poor recovery, while those with absent or slight preoperative thalamus deformation showed a good recovery. Conclusion Patients with preoperative thalamus deformation caused by pressure and edema show a poor oral intake and communication abilities after DC, suggesting that preoperative thalamus deformation is a predictor of poor functional outcomes after DC in patients with malignant MCA infarction.

The feeding habit of sea turtles influences their reaction to artificial marine debris.

Ingestion of artificial debris is considered as a significant stress for wildlife including sea turtles. To investigate how turtles react to artificial debris under natural conditions, we deployed animal-borne video cameras on loggerhead and green turtles in addition to feces and gut contents analyses from 2007 to 2015. Frequency of occurrences of artificial debris in feces and gut contents collected from loggerhead turtles were 35.7% (10/28) and 84.6% (11/13), respectively. Artificial debris appeared in all green turtles in feces (25/25) and gut contents (10/10), and green turtles ingested more debris (feces; 15.8 ± 33.4 g, gut; 39.8 ± 51.2 g) than loggerhead turtles (feces; 1.6 ± 3.7 g, gut; 9.7 ± 15.0 g). In the video records (60 and 52.5 hours from 10 loggerhead and 6 green turtles, respectively), turtles encountered 46 artificial debris and ingested 23 of them. The encounter-ingestion ratio of artificial debris in green turtles (61.8%) was significantly higher than that in loggerhead turtles (16.7%). Loggerhead turtles frequently fed on gelatinous prey (78/84), however, green turtles mainly fed marine algae (156/210), and partly consumed gelatinous prey (10/210). Turtles seemed to confuse solo drifting debris with their diet, and omnivorous green turtles were more attracted by artificial debris.

Intractable Neurosarcoidosis Effectively Treated with Infliximab.

We herein describe the case of an 18-year-old girl who presented with dizziness and headache in 2012. In 2013, brain magnetic resonance imaging revealed multiple intracerebral small lesions and intracerebral hydrocephalus. She was diagnosed with neurosarcoidosis following a brain biopsy. Although prednisolone, methotrexate, and azathioprine were administered, her hydrocephalus worsened and her granulomatous lesions were observed to increase in number on MRI. The patient's hydrocephalus showed no improvement despite her undergoing one ventriculoperitoneal shunt procedure, one septum pellucidum fenestration, and three ventriculoatrial shunt procedures. Infliximab therapy was then initiated, which resulted in a reduction in the size of the granulomatous lesions and the improvement of the patient's clinical symptoms. Infliximab may be a viable therapeutic option for treating intractable neurosarcoidosis.

Clinical Features of Ischemic Stroke during Treatment with Dabigatran: An Association between Decreased Severity and a Favorable Prognosis.

OBJECTIVE: Anticoagulation therapy with warfarin is associated with a favorable prognosis in ischemic stroke. Dabigatran, a new oral anticoagulant, is widely used to prevent ischemic stroke in non-valvular atrial fibrillation (NVAF) patients. However, its association with decreased severity and a favorable prognosis once ischemic stroke has occurred remains unknown. METHODS: We retrospectively reviewed all the patients with NVAF-associated ischemic stroke admitted to our hospital from April 2011 to December 2014 and included those who received dabigatran therapy. We assessed whether the patients were under regular use of the drug or discontinuance and classified them into 2 groups, the treatment and discontinuation groups. Clinical data, including the age, sex, ASCOD stroke phenotype, NVAF type, prescribed drug dose, comorbidities, CHADS2 score, renal function, National Institute of Health Stroke Scale (NIHSS) score on admission, modified Rankin scale (mRS) score at discharge, D-dimer, and brain natriuretic peptide, were investigated and compared between the groups. RESULTS: Nine patients were under regular dabigatran therapy, and 6 were under discontinuance of the drug. The age, sex, ASCOD stroke phenotype, NVAF type, comorbidities, renal function, and CHADS2 scores did not differ between the 2 groups; however, the NIHSS scores were significantly lower in the treatment group. The mRS scores at discharge were additionally decreased in the treatment group. Moreover, the D-dimer scores were lower in the treatment group, thus suggesting a possible role in the decreased stroke severity. CONCLUSION: Dabigatran may therefore decrease the severity of ischemic stroke, even if ischemic stroke occurs.

Platelet-endothelial cell interaction in brain microvessels of angiotensin II type-2 receptor knockout mice following transient bilateral common carotid artery occlusion.

The purpose of this study was to investigate the behavior of platelets (rolling and adhesion) in cerebral microvessels of angiotensin II type-2 receptor-knockout (AT2RKO) mice after transient bilateral carotid artery occlusion using intravital fluorescence microscopy. Twenty AT2RKO mice, consisting of 11 mice in the sham group and 9 mice in the ischemia reperfusion group (reperfusion after 15 min of bilateral, total carotid artery occlusion) were used in this study. The hole traversed the bone and dura mater, but arachnoid, pia mater, and cerebral parenchyma were preserved. Platelets were harvested from donor mice and stained using carboxyfluorescein diacetate succinimidyl ester. The number of platelets showing rolling and adhesion to pial vessels in AT2 deficient mice at 3 and 6 h after cerebral ischemia reperfusion was significantly higher than that in the sham group (P < 0.05). In addition, AT2 receptor has an inhibitory role in platelet rolling and adhesion after cerebral ischemia reperfusion.

Ischemic stroke with essential thrombocythemia: a case series.

BACKGROUND: Essential thrombocythemia (ET) is considered a rare cause of stroke partly because it is not detected if the platelet count is not elevated. However, early detection of ET is important because thrombosis can recur frequently, unless adequately treated. METHODS: We retrospectively collected data from 10 stroke cases with ET. Clinical characteristics, location of stroke, laboratory data (platelet and leukocyte count, hemoglobin, and JAK2 V617F mutation), and treatment were reviewed. RESULTS: The population consisted of 7 women and 3 men aged 18-83 years. Most patients had atherosclerotic risk factors. Half of the patients had a history of ischemic stroke. In 8 patients, ischemic stroke was the first manifestation of ET. Of 13 acute cerebrovascular events, 4 were transient ischemic attacks and 9 were cerebral infarctions. Three patients presented with watershed-type infarcts without large artery stenosis. Two patients had atherosclerotic stenosis of the large artery and experienced atherothrombotic infarction. The mean platelet count was 966 ± 383 × 10(9)/L. JAK2 V617F mutation was found in 5 of 7 patients. Despite treatment with combined antiplatelet and cytoreductive therapy in all patients, 3 experienced recurrent ischemic stroke. CONCLUSIONS: These findings suggest that ET is an adjunctive risk factor for stroke and the patients with ET are subject to watershed-type infarcts even in the absence of large artery stenosis. Early diagnosis of ET and strict management of vascular risk factors may help prevent additional cerebrovascular events.

Relationship between smoking and responsiveness to clopidogrel in non-cardiogenic ischemic stroke patients.

OBJECTIVE: Clopidogrel is used to prevent the recurrence of non-cardiogenic ischemic stroke, but individual responsiveness to the drug varies. Moreover, it is known that smoking, which is a risk factor for ischemic stroke, affects the drug's pharmacokinetics. The objective of the present study was to investigate a possible relationship between smoking and responsiveness to clopidogrel in non-cardiogenic ischemic stroke patients. METHODS: The study involved 209 non-cardiogenic ischemic stroke patients who were administered oral clopidogrel at a dosage of 75 mg/day for at least 1 week. Platelet aggregation in response to adenosine diphosphate (20 µM) was measured in each patient using the VerifyNow P2Y12 Assay. Platelet aggregation and the incidence of resistance to clopidogrel were compared between a smokers group (70 patients) and a non-smokers group (139 patients). Clopidogrel resistance was defined as a P2Y12 Reaction Units (PRU) value >230 and/or % inhibition <20%. RESULTS: The mean PRU was 128.3±85.5 in the smokers group and 167.7±86.6 in the non-smokers group (p=0.002). The incidence of PRU >230 was 12.9% (9 patients) in the smokers group and 25.9% (36 patients) in the non-smokers group (p=0.033). The mean % inhibition was 48.6±30.7% in the smokers group and 36.9±27.6% in the non-smokers group (p=0.009). The incidence of patients with % inhibition <20% was 24.3% (17 patients) in the smokers group and 34.5% (48 patients) in the non-smokers group (p=0.155). CONCLUSION: The incidence of clopidogrel resistance was lower in the non-cardiogenic ischemic stroke patients who were smokers, thus indicating that these patients' responsiveness to this drug may be enhanced.

Clinical outcomes of persistent and paroxysmal atrial fibrillation in patients with stroke.

BACKGROUND: We compared the clinical outcomes of persistent atrial fibrillation (PeAF) and paroxysmal atrial fibrillation (PAF) in patients with cardioembolic stroke caused by nonvalvular atrial fibrillation (NVAF) because the nature of the fibrillation can cause persistent cerebral infarction. METHODS: We classified 619 of 964 patients hospitalized with cardioembolic stroke between April 2007 and December 2013 within 24 hours of onset as having PeAF (n = 447) and PAF (n = 172) according to a retrospective analysis of their clinical records, including National Institutes of Health Stroke Scale (NIHSS) scores on admission, clinical outcomes (modified Rankin Scale [mRS] scores) at 90 days after admission, and major cerebral artery occlusion. RESULTS: The PeAF group was significantly older (P < .001) and had a higher prevalence of hypertension (P = .007), diabetes (P = .039), heart failure (P = .004), previous coronary artery disease (P = .002) and cerebral infarction (P < .001), medication with anticoagulants (P < .001), and elevated blood glucose on admission (P = .002). Neurologic severity assessed by NIHSS scores on admission was significantly worse in the PeAF than in the PAF group (P < .001). Significantly more patients in the PAF group had favorable outcomes (mRS, 0-2) after 90 days (P < .001). The incidence of major cerebral artery occlusion was significantly higher in the PeAF group (P < .001). CONCLUSIONS: Patients with PeAF and cardioembolic stroke due to NVAF had more severe neurologic deficits on admission, more frequent major arterial occlusion, and poorer outcomes than those with PAF.

Research article: clinical characteristics of isolated anterior cerebral artery territory infarction due to arterial dissection.

BACKGROUND: Isolated brain infarction in the anterior cerebral artery (ACA) territory is rare, and its etiology has not yet been fully elucidated. Thus, we aimed to determine the etiologic and clinical characteristics of patients with isolated ACA territory infarction due to arterial dissection. METHODS: Of 2315 patients with acute cerebral infarction admitted to our hospital between April 2007 and September 2013, 34 patients (1.5%; 28 men, 6 women; mean age, 65 ± 15 years) suffered isolated ACA territory infarction. We performed cranial magnetic resonance (MR) imaging and MR angiography for all the patients. Whenever possible, we also performed 3-dimensional computed tomography angiography, digital subtraction angiography, and MR cisternography to diagnose the stroke subtype. RESULTS: The stroke subtypes of the 34 patients with isolated ACA territory infarction were atherothrombotic infarction, cardioembolic infarction, arterial dissection, and unclassified in 11 patients (32%), 11 patients (32%), 11 patients (32%), and 1 patient (3%), respectively. The mean ages at onset were 48 ± 9 and 72 ± 11 years in the dissection and nondissection groups, respectively (P < .001). Headaches were present at onset in 4 patients (36%) and 1 patient (4%) with and without dissection, respectively (P = .026). Blood pressure at onset was significantly higher among patients with dissection (systolic, 179 ± 34 mm Hg; diastolic, 102 ± 17 mm Hg) than among patients without dissection (systolic, 155 ± 30 mm Hg; diastolic, 86 ± 21 mm Hg; P < .05), and d-dimer values were significantly lower among patients with dissection (P = .034). Favorable clinical outcome (modified Rankin Scale score, 0-2) at discharge was achieved in 9 patients (82%) and 10 patients (43%) with and without dissection, respectively (P = .035). CONCLUSIONS: Patients with isolated ACA territory infarction demonstrated a relatively high frequency of dissection (32%). Patients with dissection were younger, had a higher frequency of headaches, and demonstrated more favorable prognoses than patients without dissection.