Biomedical subjects

Jun Kojima

Publications and source records attributed to Jun Kojima.

6 recordsLinked to original sources

PubMed2006

Amiodarone pulmonary toxicity: a patient with three recurrences of pulmonary toxicity and consideration of the probable risk for relapse.

A 44-year-old man was treated with amiodarone for dilated cardiomyopathy. After 53 months, he developed amiodarone-induced interstitial pneumonia. Amiodarone treatment was terminated, and the patient was given corticosteroids. These treatments were effective. However, pneumonitis recurred whenever prednisolone was reduced to less than 5 mg per day. Considering the patient's background characteristics, we considered his body mass index (BMI, kg/m(2)) and found his to be high. When four additional patients with amiodarone pulmonary toxicity were reviewed at our institute, a correlation between BMI and the duration of shadow disappearance was found (R(2)=0.8695). Because amiodarone is lipophilic, the patient's high BMI might have influenced the repeated appearance of pulmonary toxicity.

Adult↗

PubMed2005

Cerebral salt wasting in subarachnoid hemorrhage rats: model, mechanism, and tool.

Cerebral salt wasting (CSW) frequently occurs concomitantly with aneurysmal subarachnoid hemorrhage (SAH). CSW induces excessive natriuresis and osmotic diuresis, and reduces total blood volume. As a result, the risk of symptomatic cerebral vasospasm may be elevated. Therefore, it is important to determine the mechanism of CSW. The purpose of this study was to evaluate whether the rat SAH model exhibits CSW and to investigate the relationship between CSW and natriuretic peptides. A SAH model was produced in 24 rats by perforating a cerebral artery with a nylon thread up through the common carotid artery. To evaluate CSW, urine was cumulatively collected from SAH onset to 12 hours and sodium (Na) excretion was analyzed. Body weight and hematocrit were analyzed before and after SAH onset. Concentrations of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in plasma were also analyzed. Urine volume and total Na excretion of SAH rats were significantly higher than those of sham rats (p<0.05). Body weight of SAH rats significantly decreased and hematocrit significantly increased (p < 0.05). ANP concentration was significantly decreased in SAH rats (p<0.05). However, BNP concentrations did not change. This study demonstrated for the first time that a rat SAH model exhibited CSW. It was suggested that the cause of CSW was neither ANP nor BNP. In addition, this rat SAH model will be useful for study of CSW after SAH.

Animals↗

PubMed2003

Prophylactic management of excessive natriuresis with hydrocortisone for efficient hypervolemic therapy after subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: Hyponatremia caused by excessive natriuresis is common in patients with aneurysmal subarachnoid hemorrhage (SAH). Natriuresis decreases the total blood volume through osmotic diuresis and increases the risk of symptomatic cerebral vasospasm. In such patients, hypervolemic therapy is difficult to achieve without causing hyponatremia because sodium replacement provokes further natriuresis and osmotic diuresis. We examined the effects of hydrocortisone, which promotes sodium retention, in patients with SAH. METHODS: Twenty-eight SAH patients were randomized into 2 groups after direct surgery: group 1 patients without hydrocortisone treatment (n=14) and group 2 patients with hydrocortisone treatment (1200 mg/d for 10 days; n=14). Both groups underwent hypervolemic therapy by aggressive sodium and water replacement. The goal of the hypervolemic therapy was to maintain the serum sodium level >140 mEq/L and the central venous pressure (CVP) within 8 to 12 cm H2O. RESULTS: Group 2 demonstrated a lower sodium excretion (P<0.05) and higher serum sodium level (P<0.05) compared with group 1. Hyponatremia developed in 6 patients (43%) in group 1 and 0 patients in group 2 (P<0.05). Group 2 also demonstrated a lower urine volume, lower infusion volume (P<0.05) required for hypervolemic therapy, and higher CVP (P<0.05). Failure to maintain CVP was observed in 12 patients (86%) in group 1 and 3 patients (21%) in group 2 (P<0.05). Hydrocortisone caused no serious side effects. CONCLUSIONS: Hydrocortisone clearly attenuates excessive natriuresis. Prophylactic hydrocortisone administration appears to have a therapeutic value in inducing hypervolemia efficiently after SAH.

Adult↗

PubMed2003

Differential pharmacokinetics of theophylline in elderly patients.

The clinical use of theophylline as a first-line bronchodilator has declined during the last two decades. However, in many clinical settings, such as an emergency bronchial asthma attack, theophylline may have a first-line role, in combination with beta(2)-adrenoreceptor agonists and corticosteroids, for improving the asthmatic status. Furthermore, many therapeutic mechanisms of theophylline for bronchial asthma have been reported, and recent studies have suggested that theophylline therapy may have a beneficial role in the management of chronic stable asthma as well as exacerbated disease. However, theophylline has a low therapeutic index because the bronchodilation it produces has a linear relationship with logarithmic increases in serum concentration for the therapeutic range of 5-20 mg/L. Thus, the knowledge of its basic pharmacokinetics and the factors that can alter its clearance is clinically relevant for physicians. Especially when used in elderly asthmatic patients, dosage adjustment of theophylline is a requisite since the elderly have several risk factors that may increase the plasma theophylline level, such as reduced clearance, various underlying diseases and multiple coadministered drugs. After theophylline treatment has been initiated, therapeutic drug monitoring is required.

Aged↗

PubMed2002

Laser pulse-stretching with multiple optical ring cavities.

We describe a simple and passive nanosecond-long laser-pulse stretcher using multiple optical ring cavities. We present a model of the pulse-stretching process for an arbitrary number of optical ring cavities. This new model explicitly includes the effects of cavity delay time, beam-splitter reflectivity, total number of optical cavities, and describes the effects of spatial profile sensitivity. Using the model, we optimize the design of a pulse stretcher for use in a spontaneous Raman-scattering excitation system that avoids laser-induced plasma spark problems. From the optimized design, we then experimentally demonstrate and verify the model with a three-cavity pulse-stretcher system that converts a 1000-mJ, 8.4-ns-long input laser pulse into an approximately 75-ns-long (FWHM) output laser pulse with a peak power reduction of 0.10x and an 83% efficiency.

Journal Article↗

PubMed2002

A network representation of response probability in the striatum.

The striatum of the basal ganglia is considered a key structure in the learning circuitry of the brain. To analyze neural signals that underlie striatal plasticity, we recorded from an identifiable class of striatal interneurons as macaque monkeys underwent training in a range of conditioning and non-associative learning paradigms, and recorded eyeblink electromyographs as the measure of behavioral response. We found that the responses of these striatal interneurons were modifiable under all training conditions and that their population responses were tightly correlated with the probability that a given stimulus would evoke a behavioral response. Such a network signal, proportional to current response probability, could be crucial to the learning and decision functions of the basal ganglia.

Animals↗