[Effect of Relative Electron Density and Physical Density Adjustment in Patient-specific Quality Assurance Using PMMA Phantom].

PURPOSE: The purpose of this study was to improve the accuracy of dose-distribution calculations by understanding how the calculated dose varies with the change in the relative electron density replacing polymethyl methacrylate (PMMA) in patient-specific quality assurance. METHOD: We calculated the relative electron density at which dose attenuation in each dose calculation algorithm coincides with the measured value of the dose attenuation of single-field irradiation. Next, the dose change was calculated by changing the relative electron density or physical electron density for substituting PMMA for each X-ray energy and calculation algorithm. Furthermore, using clinical plans, changes in point-dose verification and dose-distribution verification that occurred when the relative electron density or physical electron density was varied were investigated. RESULTS: The dose attenuation varies depending on the dose-calculation algorithm, and the optimum value of the electron density is different for each. After the electron density optimization, the point dose verification using the 97.1% to 98.3% (3%/3 mm), 90.0% to 94.3% (2%/3 mm) and gained a dominant improvement tendency (P<0.001). CONCLUSIONS: We clarified dose change accompanying relative electron density or physical electron density change. We concluded that the accuracy of dose-distribution calculation for verification improves by replacing PMMA with optimal relative electron density or physical electron density.

Effects of L-/N-Type Calcium Channel Blockers on Angiotensin II-Renin Feedback in Hypertensive Patients.

OBJECTIVES: Cilnidipine, an L-/N-type calcium channel blocker (CCB), has unique organ-protective properties due to suppression of hyperactivity in the sympathetic nervous system and renin-angiotensin system (RAS). In this study, we hypothesized that cilnidipine might exert a renoprotective effect by suppressing the RAS. METHODS: A total of 25 hypertensive patients receiving a RAS inhibitor were randomly assigned to a cilnidipine (n = 12) or amlodipine (n = 13) group. The effects of cilnidipine on proteinuria and angiotensin II-renin feedback were assessed. RESULTS: After 6 months of treatment, both systolic and diastolic blood pressures were significantly reduced to a similar extent in both groups. The urine albumin-to-creatinine ratio was significantly lower in the cilnidipine group (p < 0.05) than in the amlodipine group. Amlodipine increased plasma angiotensin I and angiotensin II levels (p < 0.05), whereas cilnidipine did not. Interestingly, the cilnidipine group had a higher ratio of angiotensin-(1-7) (Ang-(1-7)) to angiotensin II in plasma than the amlodipine group (p < 0.05). CONCLUSIONS: The L-/N-type CCB cilnidipine, but not amlodipine, decreased urinary albumin excretion in hypertensive patients. Cilnidipine also increased the ratio of Ang-(1-7) to angiotensin II in plasma, which might be one factor underlying its beneficial effects.

Online tool for calculating null points in various inversion recovery sequences.

Accurate equations for calculating the inversion time of the null point (TInull) in inversion recovery (IR) sequences are required for adequate suppression of fat or cerebrospinal fluid (CSF) but are not widely known. The purpose of this study is to elucidate the process of deriving accurate TInull equations using schematic diagrams that allow the equations to be easily understood, and to devise a convenient online tool for instant calculation of TInull. We investigated various IR sequences in which a 180° inversion pulse is followed by spin echo (SE) type sequences, termed IR-SE-type sequences, including FLAIR (fluid attenuated inversion recovery), STIR (short inversion time inversion recovery), and SPAIR (spectral adiabatic inversion recovery, spectral attenuated inversion recovery). We classified these sequences into three types according to the behavior of the longitudinal magnetization before the next IR pulse: having a train of multiple spin echoes, a single spin echo, or a train of multiple inversions by SPAIR pulses (with no spin echo). For each sequence type, we produced a precise diagram of the behavior of the longitudinal magnetization and clarified the process of deriving the equation for TInull. Three accurate TInull equations were derived. We created an online tool that calculates TInull using these three equations. The validity of the resulting TInull was evaluated on pelvic SPAIR diffusion-weighted (DW) images at 3T in 21 volunteers, using various inversion times (TI) around the calculated TInull. The tool displays the calculated TInull value instantly, after inputting imaging parameters and the T1 values of fat or CSF. The TInull values calculated using the tool achieved sufficient suppression in all subjects. When the actual TI value differed by more than 5% from the calculated TInull value, the fat suppression effect was significantly less on pelvic SPAIR DW images (P<0.01). In conclusion, this online tool is easily available and enables adequate suppression of fat or CSF according to the imaging parameters.

Two cases of acute myocardial infarction during combined chemotherapy in young patients with testicular cancer.

The two patients were males aged over 30 years. To treat testicular tumors, combination chemotherapy with bleomycin, etoposide, and cisplatin (BEP) had been employed. In case 1, during the 4th course of BEP therapy, thoracic pain suddenly appeared. Emergency coronary angiography revealed thrombus formation. Under a diagnosis of thrombus-related acute myocardial infarction, thrombus aspiration was conducted, and stent implantation was performed because mild stenosis and residual thrombus were observed. In case 2, during the 2nd course of BEP therapy, thoracic pain suddenly appeared. Emergency coronary angiography revealed thrombus formation. Intracoronary infusion of pro-urokinase was performed, and additional balloon dilatation was conducted because mild stenosis and residual thrombus were observed. In both cases, the courses were favorable, and the levels of coagulation markers on admission were high. When selecting combination chemotherapy in patients with coronary risk factors, such as obesity and smoking, despite a young age, as demonstrated in these two patients, it may be important to consider combination therapy with anticoagulants or switching to anticancer drugs that do not show vascular toxicity. .

Renoprotective and antioxidant effects of cilnidipine in hypertensive patients.

Cilnidipine, an L/N-type calcium channel blocker (CCB), has been reported to have more beneficial effects on proteinuria progression in hypertensive patients than amlodipine, an L-type CCB. The N-type calcium channel blockade that inhibits renal sympathetic nerve activity might reduce glomerular hypertension by facilitating vasodilation of the efferent arterioles. However, the precise mechanism of the renoprotective effect of cilnidipine remains unknown. Because cilnidipine exerted significantly higher antioxidant activity than amlodipine in cultured human mesangial cells, we hypothesized that cilnidipine might exert a renoprotective effect by suppressing oxidative stress. A total of 35 hypertensive patients receiving a renin-angiotensin system inhibitor were randomly assigned to a cilnidipine (n=18; 10 mg per day cilnidipine titrated to 20 mg per day) or amlodipine (n=17; 5 mg per day amlodipine titrated to 10 mg per day) group; the target blood pressure (BP) was set at 130/85 mmHg. After 6 months of treatment, systolic and diastolic BPs were significantly reduced in both of the groups, without any significant difference between the groups. The urinary albumin, 8-hydroxy-2'-deoxyguanosine (OHdG) and liver-type fatty-acid-binding protein (L-FABP) to creatinine ratios significantly decreased in the cilnidipine group (P<0.05) compared with those in the amlodipine group. The reductions in urinary albumin, 8-OHdG and L-FABP were not correlated with the change in systolic BP. In conclusion, cilnidipine, but not amlodipine, ameliorated urinary albumin excretion and decreased urinary 8-OHdG and L-FABP in the hypertensive patients. Cilnidipine probably exerts a greater renoprotective effect through its antioxidative properties.

Extended observation of the nasal cycle using a portable rhinoflowmeter.

OBJECTIVE: Nasal patency varies owing to the effects of humidity, temperature, and exercise. In addition, periodic cycles of congestion and decongestion that alternate between the right and the left side of the nose, which are termed the "nasal cycle," have been observed. The physiologic mechanisms underlying this cycle are not clear. Sympathetic nerves that supply the nose are regulated by the hypothalamus and the vasomotor areas of the brainstem. It is possible that the nasal cycle could be involved in protection against respiratory infection or allergies. Conventional methods of studying the nasal cycle, including rhinomanometry and acoustic rhinometry, impose limitations on the location and timing of evaluation. We studied the nasal cycle using a new portable device for relatively long-term rhinoflowmetry. METHODS: Twenty normal subjects aged 24 to 77 years were fitted with the portable rhinoflowmeter (Rhinocycle, Rhinometrics, Lynge, Denmark) to continuously measure nasal air flow via each nostril over 12 daytime hours. RESULTS: No subject complained of discomfort owing to the device, and 14 of them showed a detectable nasal cycle. The mean nasal cycle duration was 110 minutes, although variation was considerable, even in a single subject. CONCLUSIONS: The portable device proved useful for observing the nasal cycle, and it should be valuable for the general investigation of nasal physiology.

Potassium current properties in apical and basal inner hair cells from guinea-pig cochlea.

Inner hair cells (IHCs) of guinea-pigs were separately isolated from the apical and basal turn and the potassium currents were measured by the whole-cell voltage-clamp technique. The potassium current flows through two types of membrane conductance: a fast (I(k,f)), tetraethylammonium (TEA)-sensitive conductance and a slow (I(k,s)), TEA-resistant conductance. Membrane conductance demonstrated no significant differences between apical IHCs and basal IHCs. Reversal potentials were -65+/-2 mV and -68+/-5 mV in apical and basal IHCs, respectively. The rate of outward current activation was voltage dependent and faster in basal IHCs than in apical IHCs. TEA effect was stronger on basal IHCs than on apical IHCs, suggesting that I(k,f) is dominant in basal IHCs.