The correlation between vertebral artery asymmetry and pontine infarction--an MR angiography study]

The purpose of this study is to evaluate the correlation between variation of the vertebral artery (VA) and the incidence of pontine infarction. A total of 206 patients were examined using magnetic resonance imaging (MRI) and 3-dimension time-of-flight MR angiography (MRA) of the brain. Of these, 54 patients had pontine infarctions (23 symptomatic and 31 asymptomatic), and the majority of them were located in the pontine base. The sites of dominant lesion in the pons were right in 18 cases, left in 8 cases, and bilateral in 28 cases. The number of patients with VA asymmetry (the ratio of internal diameters 1:2 or more) were 89 (43.2%). Of these, 67 patients had small diametric VA of right side, and 22 of left side. Among the 117 patients with normal VA pattern, 19 (16.2%) had infarction, while among the 89 patients with VA asymmetry, 35 (39.3%) had infarction. The patients with small diametric VA of right side significantly had infarctions in the same side of the pons. The results of this study suggest that VA asymmetry is considered to be one of the risk factors of pontine infarction and that MRA can be useful in the examination of the cerebral artery as a valuable and non-invasive screening method.     

Optimization of self-reference thermometry using complex field estimation.

Referenceless, or self-reference, thermometry is a technique for mapping temperature differences in the region of interest (ROI) using the baseline phase estimated by extrapolating the field in the surrounding region for estimation (RFE) and subtracting the estimated baseline from the measured field. In the present work a self-reference technique based on complex field estimation using 2D polynomials comprising complex-valued coefficients was proposed and optimized. Numerical simulations with a Gaussian-profiled phase distribution demonstrated that the ROI radius had to be 2.3-2.5 times the standard deviation (SD) of the Gaussian function in order to keep the error below 8% of the peak phase change. The area ratio between the ROI and the RFE had to be larger than 2.0 to maintain the error level. Based on the simulations, and phantom and volunteer experiments, the complex-based method with independently optimized polynomial orders for the two spatial dimensions was compared with the phase-based method using the similar-order optimization strategy. The complex-based method appeared to be useful when phase unwrapping was not removed. Otherwise, the phase-based method yielded equivalent results with less polynomial orders.     

Gorog Thrombosis Test: analysis of factors influencing occlusive thrombus formation.

We used the Gorog Thrombosis Test to analyze the factors influencing the occlusion time, which represents platelet activation and subsequent occlusive thrombus formation, in 132 healthy Japanese volunteers (116 men, 16 women; mean age, 45.0 +/- 12.0 years). The Gorog Thrombosis Test was designed to evaluate platelet aggregation and thrombolytic activity under a high shear stress condition (175 dynes/cm) in a native blood sample in vitro. The mean +/- SD occlusion time was 154.8 +/- 64.7 s (men, 153.4 +/- 64.2 s and women, 165.4 +/- 56.5 s). The occlusion time was inversely correlated with von Willebrand factor ristocetin cofactor activity (VWF:Rco) (r = -0.242, P = 0.0055) and von Willebrand factor antigen (r = -0.230, P = 0.0080). The mean occlusion time in the group with VWF:Rco of at least 170% (137 s) was significantly shorter than that in the group with VWF:Rco less than 170% (156 s, P < 0.05). Platelet counts, other coagulation markers and smoking showed no significant correlations with occlusion time. Red blood cells (r = -0.177, P = 0.0365), hemoglobin (r = -0.191, P = 0.0245) and hematocrit (r = -0.182, P = 0.0329) also showed inverse correlations with the occlusion time. This report is the first to clearly demonstrate the role of von Willebrand factor in the formation of occlusive thrombi in the Gorog Thrombosis Test.     

Diuretic and hypotensive actions of torasemide in hypertensive models of rat

The diuretic and the antihypertensive actions of torasemide were examined in renal and genetic hypertensive rats and compared to the effects of furosemide. Oral administration of torasemide (1 and 3 mg/kg) elicited a dose-dependent increase in the excretion of urine and electrolytes and elevated the urinary Na/K ratio in both renal and genetic hypertensive rats. Torasemide and furosemide had a similar maximum diuretic effect in the normotensive Wistar rat and the spontaneously hypertensive rat (SHR). However, the diuretic activity of furosemide was weaker in the renal hypertensive rat (RHR). Torasemide showed approximately 30 times greater diuretic potency than furosemide. Torasemide and furosemide demonstrated hypotensive action in hypertensive rat models, but not in the normotensive Wistar rat. Especially in the RHR, torasemide exhibited a more potent hypotensive action than furosemide. These results show that the diuretic and antihypertensive activities of torasemide are effective in various rat models of hypertension, while the diuretic activity of furosemide is weak in certain hypertensive rat models. © 1992 Wiley-Liss, Inc.     

Toluene vapor exposure and urinary excretion of hippuric acid among workers in China.

A factory survey was conducted in three provinces in China from 1985 to 1989. The time-weighted average toluene concentrations in breathing zone air were monitored by diffusive sampling, whereas hippuric acid (HA) concentrations in shift-end urine samples were measured by high performance liquid chromatography (HPLC). Exposed workers (456 men and women) were those for whom toluene (up to 548 ppm toluene) accounted for greater than or equal to 90% of total exposure (by vapor concentration in ppm), whereas 517 nonexposed controls were recruited from the same factories or from factories of the same region. There was a linear correlation between the intensity of toluene exposure and HA concentration in the shift-end urine. Comparison of the results with findings in the literature shows that the toluene-induced increase in urinary HA concentration among workers in China is significantly smaller than the published values, whereas HA concentrations in urine samples from nonexposed controls are comparable to the levels previously reported.     

Effects of drugs acting on Cl(-)-HCO3- and Na(+)-H+ exchangers on acid secretion in the rat gastric mucosa sheet preparation.

The effects of 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), an inhibitor of the Cl(-)-HCO3- exchanger, and amiloride, an inhibitor of the Na(+)-H+ exchanger, on gastric acid secretion under basal conditions and after stimulation with bethanechol or dibutyryl cyclic AMP were studied in rat gastric mucosa sheet preparation. DIDS inhibited bethanechol-induced acid secretion in a dose-dependent manner, but amiloride had no effect. The stimulation of acid secretion by dibutyryl cyclic AMP plus 3-isobutyl-1-methylxanthine was also inhibited by DIDs, but not by amiloride. DIDS did not reduce basal acid secretion, and neither did amiloride. These results suggest that the Cl(-)-HCO3-exchanger in the basolateral membrane of the parietal cell plays an important role in stimulated gastric acid secretion and that the Na(+)-H+ exchanger is less important. In addition, these data show that DIDS inhibits stimulated gastric acid secretion irrespective of the secretagogue, but not basal gastric acid secretion.