Characterization of action potential-triggered [Ca2+]i transients in single smooth muscle cells of guinea-pig ileum

1. To characterize increases in cytosolic free Ca²⁺ concentration ([Ca²⁺]_i) associated with discharge of action potentials, membrane potential and [Ca²⁺]_i were simultaneously recorded from single smooth muscle cells of guinea-pig ileum by use of a combination of nystatin-perforated patch clamp and fura-2 fluorimetry techniques.
2. A single action potential in response to a depolarizing current pulse elicited a transient rise in [Ca²⁺]_i. When the duration of the current pulse was prolonged, action potentials were repeatedly discharged during the early period of the pulse duration with a progressive decrease in overshoot potential, upstroke rate and repolarization rate. However, such action potentials could each trigger [Ca²⁺]_i transients with an almost constant amplitude.
3. Nicardipine (1 μM) and La³⁺ (10 μM), blockers of voltage-dependent Ca²⁺ channels (VDCCs), abolished both the action potential discharge and the [Ca²⁺]_i transient.
4. Charybdotoxin (ChTX, 300 nM) and tetraethylammonium (TEA, 2 mM), blockers of large conductance Ca²⁺-activated K⁺ channels, decreased the rate of repolarization of action potentials but increased the amplitude of [Ca²⁺]_i transients.
5. Thapsigargin (1 μM), an inhibitor of SR Ca²⁺-ATPase, slowed the falling phase and somewhat increased the amplitude, of action potential-triggered [Ca²⁺]_i transients without affecting action potentials. In addition, in voltage-clamped cells, the drug had little effect on the voltage step-evoked Ca²⁺ current but exerted a similar effect on its concomitant rise in [Ca²⁺]_i to that on the action potential-triggered [Ca²⁺]_i transient.
6. Similar action potential-triggered [Ca²⁺]_i transients were induced by brief exposures to high-K⁺ solution. They were not decreased, but rather increased, after depletion of intracellular Ca²⁺ stores by a combination of ryanodine (30 μM) and caffeine (10 mM) through an open-lock of Ca²⁺-induced Ca²⁺ release (CICR)-related channels.
7. The results show that action potentials, discharged repeatedly during the early period of a long membrane depolarization, undergo a progressive change in configuration but can each trigger a constant rise in [Ca²⁺]_i. Intracellular Ca²⁺ stores have a role, especially in accelerating the falling phase of the action potential-triggered [Ca²⁺]_i transients by replenishing cytosolic Ca²⁺. No evidence was provided for the involvement of CICR in the action potential-triggered [Ca²⁺]_i transient.

     

Keyhole method for high-speed human cardiac cine MR imaging.

Although electrocardiographic (ECG)-gated magnetic resonance (MR) imaging is widely used for cardiac imaging, it has several disadvantages, such as long imaging time, respiratory artifacts, and motion artifacts induced by arrhythmia. An MR image can be acquired within about 0.3 seconds by using a fast gradient-echo imaging method. When this method is continuously applied, only two to three images can be obtained during a single cardiac cycle. The goal of this study is to obtain cine MR images in a single cardiac cycle using fast gradient-echo imaging combined with the "keyhole" method. The optimal conditions for the keyhole method for cardiac cine imaging were obtained by computer simulation based on a simplified cardiac model. When the read-out direction was set parallel to the cardiac short axis, left ventricular motion was almost correctly reproduced by the keyhole method with acquisition time reduced to one-fourth. J. Magn. Reson. Imaging 1999;10:778-783.     

Purification and Partial Characterization of an Indomethacin Hydrolyzing Enzyme from Pig Liver

Purpose. Indomethacin is well known to be metabolized via O-demethylation and N-deacylation. In this paper we found an enzyme involved in the hydrolysis of amide-linkage of indomethacin and partially characterized it as well as its substrate specificity. Methods. An indomethacin hydrolyzing enzyme was purified to homogeneity from pig liver microsomes using columns of Q-Sepharose, Red-Sepharose and Blue-Sepharose. The enzyme activity was assayed by measuring of -chlorobenzoic acid liberated from indomethacin by HPLC. Results. The purified enzyme effectively hydrolyzed the amide linkage in indomethacin but not those in -naphthylacetate and -nitrophenylacetate, which are typical substrates for carboxylesterase. The subunit molecular mass of the enzyme was 65 kDa according SDS-polyacrylamide gel electrophoresis. The Michaelis constant (Km) and maximum velocity (Vmax) values for indomethacin were 67.8 µM and 9.02 nmol/min/mg protein, respectively. The amino acid sequence analysis of the enzyme after cyanogen bromide cleavage showed high homology with a mouse carboxylesterase isozyme designated as ES-male. The activity of indomethacin hydrolysis was relatively high in the pig, rabbit and human liver homogenate, but not in those from rat and mouse. On the other hand, purified human liver carboxylesterases pl 5.3 and 4.5, and pig liver carboxylesterases have no catalytic activity for indomethacin. Conclusions. These results indicate that the hydrolysis of amide-linkage of indomethacin in humans would be associated with an enzyme similar to the indomethacin hydrolyzing enzyme from pig liver microsomes described here.     

The validity of the MMSE and SMQ as screening tests for dementia in the elderly general population-- a study of one rural community in Japan

OBJECTIVE: To compare the validity of the Mini Mental State Examination (MMSE) and the Short-Memory Questionnaire (SMQ) as screening tests to detect dementia in the elderly general population. SUBJECTS: Six hundred and sixty-two subjects and their informants from the elderly general population sample who had completed these tests. SETTING: One rural community survey in Japan. METHOD: We used receiver-operating characteristic analysis to compare the performance of the MMSE and the SMQ with the clinical diagnosis of dementia according to DSM-III-R. RESULTS: The areas under the receiver-operating characteristic curve of the MMSE and the SMQ were 0.980 (SE = 0.006) and 0.982 (SE = 0.008), respectively. This differed from chance to a highly significant degree for both the MMSE and the SMQ, but the difference between the two scales was not statistically significant. CONCLUSION: As screening tests to detect dementia in the elderly general population, the SMQ which is assessed by informants demonstrates a statistically significant discriminating ability as well as the MMSE.     

A case of urinary stone in ureterocele extracted transurethrally after ESWL

A 66-year-old man was referred to our hospital with chief complaints of difficulty in urination and terminal micturition pain. Ureteroceles were identified bilaterally, and a ureteral stone (19 x 12 mm) existed in the right ureterocele. After crushing the stone by extra corporeal shock wave lithotripsy (ESWL), we removed the stone transurethrally with a small incision in the right ureterocele. The vesicoureteral reflux (VUR) was not detected postoperatively. Now, we recommend the combination of ESWL and a small transurethral incision of the urelerocele for the treatment of ureteral stones in a ureterocele in order to prevent postoperative VUR.     

Multivariate analysis of long-term results after an axillobifemoral and aortobifemoral bypass in patients with aortoiliac occlusive disease

BACKGROUND: Controversy still remains regarding the long-term results and indications for axillofemoral bypass (AxFB). A comparison of axillobifemoral bypass (AxBFB) and aortobifemoral bypass (ABFB) was thus conducted to determine whether AxFB is an acceptable alternative vascular procedure to anatomic bypass for high-risk patients. METHODS: Sixty-three patients who underwent a total of 25 AxBFBs and 38 ABFBs for aortoiliac occlusive disease were reviewed retrospectively, and both univariate and multivarate analyses were perfomed. RESULTS: The overall survival was 82.8% at five years. A univariate analysis revealed significantly lower survival rates for patients with limb-threatening ischemia, coronary disease, and cerebrovascular disease. A multivariate analysis disclosed no significant factors influencing survival rates. The overall primary patency was 79.8% at five years. The primary patency rates for AxBFB (67.7% at five years) were significantly lower than for ABFB (88.5% at five years) based on a univariate analysis (p=0.0045). In addition, the secondary patency rates for AxBFB (80.3% at five years) were significantly lower than for ABFB (96.5% at five years, p=0.0025). A multivariate analysis disclosed significantly lower primary patency rates for grafts with a higher angiographic outflow score and simultaneous infrainguinal reconstructive procedures, but the differences between AxBFB and ABFB were not significant. CONCLUSIONS: The survival and primary patency for the AxBFB group were both inferior to the ABFB group, however a multivarate analysis disclosed no significant differences between the two groups. Poor femoral run-off and the presence of synchronous infrainguinal reconstructive procedures significantly affected graft patency, and these factors modulated the patency of AxBFB. AxFB for aortoiliac occlusive disease is therefore considered to be an acceptable procedure in appropriately selected patients.