Acute Subdural Hematoma in High School Rugby Players in Japan: The Importance of Playing Experience for Injury Prevention.

OBJECTIVES: Acute subdural hematoma (ASDH) is known to be devasting sport-related head injury but it is relatively rare in rugby compared with other contact sports. Certain cases of ASDH have happened in high school rugby players in Japan. To prevent them from the injury we report a background of the players. METHODS: Data of high school rugby players who suffered ASDH were extracted from injury reports in the Japan Rugby Football Union between April 2004 and March 2020. The number of injured players, diagnosis on the report, school year, phase of play where the injury occurred, and playing career were analyzed. RESULTS: There were 30 cases of ASDH including 16 cases in the first year, 9 in the second year, and 5 in the third year of playing. Phase of play was mainly being tackled in 11 (37%), and tackling in 13 (43%). Novice players, defined as a player having less playing experience of rugby during junior high school, accounted for 77% of phase of tackling, 82% of being tackled. First year novice players accounted for 100% of phase of being tackled. Outcome within 6 months after injury was recovery in 14, morbidity in 6, mortality in 2, and unknown in 8. CONCLUSIONS: Playing experience in high school rugby players should be considered as an important factor for prevention of ASDH-in particular, phase of being tackled is riskier than that of tackling for first year novice players.

[Significance of tuberculosis screening of outpatients in areas with high prevalence of tuberculosis].

OBJECTIVE: The Osaka Socio-Medical Center Hospital is a medical care facility located in the Airin area of Osaka city where the prevalence of tuberculosis is high, and treats day laborers and homeless people mainly, either free of charge or with a small fee. To investigate whether this hospital can play a role to reduce the prevalence of tuberculosis in this area, we investigated the case rate of active tuberculosis in outpatients of the hospital. SUBJECTS AND METHODS: Of 1673 patients who first visited the Orthopaedic Outpatient Clinic between March 31, 2005 and June 15, 2006, 538 patients consented to undergo screening and underwent chest X-ray examination (screening group). We also analyzed chest X-ray examination in 2000 patients examined at the Department of Internal Medicine during the same period (control group). RESULTS: Of the 538 patients in the screening group (523 males and 15 females), 13 male patients (2.4%) requiring treatment were detected. Of the 2000 patients in the control group, 85 patients (84 males and 1 female) (4.3%) requiring treatment were detected. CONCLUSION: The tuberculosis case rate (2.4%) in the screening group was similar to that of tuberculosis screenings (1.1-1.8%) in the Airin area in 2004. The case rate in the control group was two times higher. Since the prevalence is very high in patients of this hospital, the hospital should play a significant role in the health care of tuberculosis patients in this community by reinforcing the screening system and enriching the outpatient clinic system.

MicroPET detection of enhanced 18F-FDG utilization by PKA inhibitor in awake rat brain.

To obtain PET imaging of glucose metabolism in the brains of conscious rats, a method of rat head fixation was developed. PET measurement with microPET was performed for 60 min after 18F-FDG injection. Significant enhancement of glucose utilization in the right striatum was observed with infusion of Rp-adenosine-3,5-cyclic phosphorothioate triethylamine (Rp-cAMPS). FDG uptake increments were also seen in the ipsilateral frontal cortex and thalamus. As initial FDG uptake in the brain was not significantly altered by Rp-cAMPS, increased glucose metabolism might be due to an increase in the phosphorylation rate by hexokinase rather than the delivery process from plasma to the brain. In contrast to awake rats, the effect of Rp-cAMPS was abolished by anesthesia using chloral hydrate, indicating that neuronal activity has an important role in short term regulation of hexokinase activity through the cAMP/PKA system in the brain. These results strongly demonstrated the value of measuring glucose utilization in the brains of conscious rats.

Role of lactate in the brain energy metabolism: revealed by Bioradiography.

To elucidate the role of lactate in the brain, we used a novel method, 'Bioradiography', in which the dynamic process could be followed in living slices by use of positron-emitter-labeled compounds and imaging plates. We studied the incorporation of 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) into rat brain slices incubated in oxygenated Krebs-Ringer solution. Under the glucose-free condition, [18F]FDG uptake rate in the cerebral cortex decreased with time and plateaued within 350 min but the addition of 5 mM lactate made the [18F]FDG uptake linear. When an inhibitor of the lactate transporter, 0.5 mM alpha-cyano-4-hydroxycinnamate (4-CIN) was applied to the glucose-free solution, the uptake rate decreased. Under the normal glucose condition, [18F]FDG uptake linearly increased for 6 h, but when 10 mM lactate was applied, the uptake rate decreased. In contrast, when 0.5 mM 4-CIN was applied to the normal glucose solution, [18F]FDG uptake rate increased. These results suggest that exogenous and endogenous lactate can substitute for glucose in the brain.

Neuropilin-2 is overexpressed in the rat brain after limbic seizures.

Structural rearrangement and synaptic reorganization are known to occur in the brain after seizures. If neuronal rearrangement after seizures always results in abnormal hyperexcitability, it would provide an accurate pathway to the appropriate target and as a result, it may be the mechanism of epileptogenesis. This study examined the mechanism of axon guidance in the mature rat brain after seizures by evaluating the expression of the axonal guidance molecule, neuropilin-2. We assessed the expression of neuropilin-2 by northern blotting and immunohistochemistry in rat with seizures created by kindling stimulation and kainate injection.The neuropilin-2 mRNA level was increased in the whole brain of the rats at 24 h after either type of seizure. Neuropilin-2 mRNA was not increased at 2 weeks after the last stimulation. Immunohistochemistry demonstrated that neuropilin-2 protein was increased in the dentate gyrus and the entorhinal cortex in the both seizure models. These findings suggested that there was overexpression of neuropilin-2 in the brains of mature rats with different types of seizure. Accordingly, neuropilin-2 might regulate remodeling after seizures as it does during the development of the hippocampal formation. Our findings suggest that axons may not project and outgrow 'aberrantly' after seizures, but may be regulated by the chemorepellent effect through neuropilin-2.

Establishment and assessment of a rat model of fatigue.

To establish an animal model of fatigue, we kept rats in a cage filled with water to a height of 1.5 cm. We selected a weight-loaded forced swimming test for evaluation of the extent of fatigue. Animals kept in the wet cage for 5 days showed a reduction in 2-[18F]fluoro-2-deoxy-D-glucose uptake into their brain. The session for 1 day showed significantly increased 5-hydroxyindoleacetic acid (5-HIAA)/5-hydroxytryptamine (5-HT) and [3,4-dihydroxyphenyl-acetic acid (DOPAC)+homovanillic acid (HVA)]/dopamine (DA) ratios in all brain regions, but the session for 5 days showed the restoration of the 5-HIAA/5-HT ratio in the hippocampus and hypothalamus and in the (DOPAC+HVA)/DA ratio in the striatum and hypothalamus. Our data suggest that decreased glucose uptake and insufficient serotonin and dopamine turnover introduced by deprivation of rest were correlated with central fatigue.

Role of acetyl-L-carnitine in the brain: revealed by Bioradiography.

To elucidate the role of acetyl-L-carnitine in the brain, we used a novel method, 'Bioradiography,' in which the dynamic process could be followed in living slices by use of positron-emitter labeled compounds and imaging plates. We studied the incorporation of 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) into rat brain slices incubated in oxygenated Krebs-Ringer solution. Under the glucose-free condition, [18F]FDG uptake rate decreased with time and plateaued within 350 min in the cerebral cortex and cerebellum, and the addition of 1 or 5mM acetyl-L-carnitine did not alter the [18F]FDG uptake rate. When a glutaminase inhibitor, 0.5mM 6-diazo-5-oxo-L-norleucine (DON), was added under the normal glucose condition, [18F]FDG uptake rate decreased. Acetyl-L-carnitine (1mM), which decreased [18F]FDG uptake rate, reversed this DON-induced decrease in [18F]FDG uptake rate in the cerebral cortex. These results suggest that acetyl-L-carnitine can be used for the production of releasable glutamate rather than as an energy source in the brain.

Assessment of microPET performance in analyzing the rat brain under different types of anesthesia: comparison between quantitative data obtained with microPET and ex vivo autoradiography.

MicroPET (positron emission tomography) has been implemented for use in experiments with small animals. However, the quantification and optimal conditions for scanning are not established yet. The aim of this study was to compare the results obtained by microPET with those by ex vivo autoradiography of rat brain slices, based on the 2-[18F]fluoro-2-deoxy-D-glucose (FDG) method, and to establish the optimal conditions for scanning. As an example, we examined glucose metabolism in the rat brain under 6 types of anesthesia and in the conscious state. The scanning conditions for the rat brain were (1) use of a 4-mm-thick leaden jacket, (2) an energy window of 350-650 keV, and (3) a coincidence time window of 6 ns. Under these conditions, the quantitative ROI data from microPET showed a good correlation with the corresponding ROI data from FDG autoradiography in the animal study (r2=0.81). With our protocol, when anesthesia was started 40 min after the FDG injection, the glucose metabolism was almost the same as that in the conscious rat brain.