Voltage-dependent decrease in the availability of single calcium channels by nitrendipine in guinea-pig ventricular cells

1. The mechanism of Ca2+ channel block by nitrendipine was studied by recording single-channel activity from cell-attached patches on guinea-pig ventricular cells using patch pipettes containing 50 mM-Ba2+. Test depolarization pulses to around 10 mV with a duration of 100 ms were applied repetitively at 2 Hz. 2. The percentage of non-blank sweeps was maximal (about 40%) at a holding potential between -65 and -130 mV and decreased sigmoidally with its depolarization. Nitrendipine shifted the availability-voltage relationship in a hyperpolarizing direction. 3. From the number of consecutive non-blank sweeps and that of blank sweeps, the duration of the available state and that of the unavailable state were estimated. 4. The histogram of the duration of the available state showed a single-exponential distribution. Its mean duration was about 1.5 s and was shortened by nitrendipine. Correspondingly, the decay of the mean current during the depolarization step was accelerated by nitrendipine. 5. In the presence of 100 nM-nitrendipine the histogram of the duration of the unavailable state at large negative holding potentials was simulated as the sum of two exponential components, one with a time constant similar to that in the control and the other with a time constant of 6-7 s. 6. The histogram of the duration of the unavailable state at depolarized holding potentials was simulated by a double-exponential curve also in the control. The duration of the slow component was prolonged by nitrendipine. 7. The prolongation of the unavailable states initiated by drug binding during depolarization steps and maintained during depolarized holding potentials is the mechanism of the blockade. The rate constants of the state transitions between an available state and two unavailable states were estimated.

Attenuation of pulmonary leukocyte sequestration during extracorporeal circulation by a new c-AMP phosphodiesterase inhibitor

Activated leukocytes may have an important role in developing complement-related lung injury, with pulmonary leukocyte sequestration in the presence of blood-material interaction in cardiopulmonary bypass and hemodialysis. The authors evaluated the effects of a new cAMP phosphodiesterase inhibitor (DN-9693) on leukocyte aggregation in vitro, utilizing canine heparinized blood and pulmonary leukocyte sequestration during extracorporeal circulation (ECC) in dogs. On in vitro evaluation, DN-9693 inhibited the leukocyte aggregation response to leukotriene B4 in a dose response manner; the aggregation response elicited by contact with a membrane lung was inhibited by a 50% inhibition dose of approximately 0.2 mumol/L. Leukocyte kinetics were assessed in a venovenous bypass system with a silicone hollow fiber membrane lung. The control group (n = 6) without DN-9693 developed a reduction in the arterial leukocyte count of 55 +/- 17% at 2 minutes of ECC. The transpulmonary difference in leukocyte count (pulmonary artery count minus systemic artery count) was significantly increased (P less than 0.05) from -175 +/- 206/microliters at baseline to 1225 +/- 330/microliters after 2 minutes of ECC. In the DN-group (n = 4, DN-9693; 60-80 micrograms/kg/min), there was no significant reduction in the arterial leukocyte count during ECC, and the transpulmonary difference showed no significant increases (75 +/- 386/microliters; baseline, versus 125 +/- 263/microliters; 2 minutes of ECC). These results suggest that DN-9693 inhibits the aggregation of leukocytes in the presence of blood-material interaction in vitro, and also prevents pulmonary leukocyte sequestration induced by ECC, with attenuation of systemic leukocyte depletion.

NMR-invisible ATP in rat heart and its change in ischemia

The subcellular compartmentalization of adenosine 5'-triphosphate (ATP) in isolated perfused rat heart and its relation to energy depletion in ischemia were examined by 31P nuclear magnetic resonance (31P-NMR) spectroscopy and chemical analyses. The signal intensities of the beta-phosphate of ATP and creatine phosphate in the 31P-NMR were standardized by the intracellular volume ratio measured with 23Na-NMR to determine the actual content of each. During aerobic perfusion the ATP content determined by NMR (13.7 +/- 2.2 mumol/g dry weight) was significantly lower than that found by chemical analysis (22.4 +/- 0.7 mumol/g dry weight), while the creatine phosphate contents determined by the two methods were the same. During ischemia at 33 degrees C, the signal of the beta-phosphate of ATP in the 31P-NMR spectrum decreased progressively, disappearing completely after 16 min. But at this time 5.7 +/- 1.7 mumol/g dry weight of myocardial ATP was still detected by chemical analysis. These results indicated that there were two different compartments of intracellular ATP in the heart, only one of which is detectable by 31P-NMR spectroscopy, and that during ischemia the ATP that is detectable, which seems to be the free ATP in the cytosol, decreased more rapidly than the ATP in the other compartment.

The characteristics of thymoma with myasthenia gravis: a 28-year experience

Of 134 patients with thymoma, 79 (59%) also had myasthenia gravis (MG). The thymoma with MG differed from that in the absence of MG in the following aspects: The ratio of lymphocytes to epithelial cells in the tumor was larger, the polygonal cell type was more prominent (i.e., in 83% of the MG patients this cell type predominated), and the differentiation of epithelial cells in the tumor was more advanced in the group with MG than in the group without MG. Furthermore, the clinical stage of thymoma was earlier, the recurrence rate was lower, and the survival curve was better in the group with MG than in the group without MG. These findings suggest that the thymoma with MG is less malignant than that without MG.

[Mass screening for the early detection of colon cancer in patients with endometrial cancer]

A mass screening has been performed for the early detection of colon cancer by evaluating Hemocult II slides of blood relatives of patients with endometrial cancer. Though the defect of this screening is that the subject of the investigation, which was undertaken in all parts of Japan, is restricted, one case of colon cancer, two cases of colon polyposis, two cases of hemorrhoids, and one case of colon diverticulum have been uncovered by this screening. The rate of discovery of colon cancer proved to be 0.45%, a rate that is higher than seen in usual screening method. It has been concluded that blood relatives of patients with endometrial cancer should be screened, since they represent a high risk group for developing colon cancer.

Thymoma: results with complete resection and adjuvant postoperative irradiation in 141 consecutive patients

A series of 141 patients with thymoma was studied with regard to the way in which complete resection followed by postoperative radiation therapy influenced prognosis according to the stage and histologic type of thymoma. Postoperative radiation therapy (30 Gy in 3 weeks to 50 Gy in 6 weeks) was performed in 73.1% of the patients. Thirty-five of 48 patients with thymoma invading the surrounding tissues (stage III) underwent complete resection, with survival rates of 100% at 5 years and 94.7% at 10 and 15 years. The prognosis in these patients was comparable with those in 45 patients with no invasion (stage I) and in 33 patients with capsular invasion (stage III), all of whom underwent complete resection. Complete resection was done in 18 of 26 patients with epithelial cell thymoma, and there were no deaths by tumor until 15 years after the operation. There were no statistically significant differences in the survival rates of patients undergoing complete resection according to cell type (33 of 36 patients with lymphocyte predominant type and 61 of 77 patients with mixed cell type). The survival rate in six patients with epithelial cell type who underwent subtotal resection was not significantly different from that of 12 patients who underwent biopsy alone. Our findings indicate that complete resection of thymoma followed by postoperative radiation therapy results in a "benign" postoperative course, regardless of the stage and histologic type. Therefore, an aggressive surgical approach, such as resection of the superior vena caval system followed by reconstruction with a ringed polytetrafluoroethylene graft and/or complete pleuropneumonectomy, is justified for advanced thymoma, although the long-term results of such extended operations are still unclear.

Novel calcium antagonists. Synthesis and structure-activity relationship studies of benzothiazoline derivatives

A series of novel compounds having a benzothiazoline skeleton was studied for their structure-activity relationship (SAR) with respect to Ca2+ antagonistic activity. As test compounds, analogues of 3-acyl-2-arylbenzothiazolines (3) were synthesized. Benzothiazoline derivatives (3) exerted higher Ca2+ antagonistic activity than the corresponding thiazolidine derivatives (2). Effects of substituents R1-R4, the substitution position of the aminoalkoxy group and R2, and the length of the methylene chain on biological activities were examined. Compound 4 [3-acetyl-2-[5-methoxy-2-[4-[N-methyl-N-(3,4,5-trimethoxyphenethyl ) amino]butoxy]phenyl]benzothiazoline hydrochloride] showed a potent Ca2+ antagonistic activity in vitro and dual inhibition on the fast Na+ inward channel and the slow Ca2+ inward channel in Langendorff perfused rabbit hearts. Compound 4 also showed a long-acting hypotensive effect in spontaneously hypertensive rats and prevented acute pulmonary thrombotic death in mice.

Myocardial energy metabolism in preserved heart: comparison of simple storage and hypothermic perfusion

Isolated canine hearts were preserved for 24 hours by either simple hypothermic storage in Collins' M solution (group 1, n = 7) or hypothermic perfusion with oxygenated modified Krebs solution (group 2, n = 7), followed in both cases by reperfusion with cross circulation. Myocardial biopsies taken consecutively during preservation and after reperfusion were analyzed for high energy phosphates (adenosine triphosphate [ATP], adenosine diphosphate [ADP], adenosine monophosphate [AMP], and creatine phosphate), their catabolites (inosine), and lactate. In group 1, ATP decreased from 23.7 +/- 2.8 mumol/gm dry weight (mean +/- standard deviation) at 0 hours to 5.6 +/- 2.8 mumol/gm dry weight at the end of preservation. Creatine phosphate decreased and lactate increased significantly during 24 hours of preservation. The consumption rate of ATP appeared to have decreased after 18 hours of preservation. In group 2, ATP, creatine phosphate, and lactate remained at control levels during preservation. Coronary vascular resistance, however, increased significantly. After reperfusion functional measurements of the hearts in both groups did not vary significantly, despite the difference in myocardial ATP content (11.2 +/- 4.9 mumol/gm dry weight in group 1 and 17.9 +/- 3.9 mumol/gm dry weight in group 2; p less than 0.05). Simple hypothermic storage manifested a limitation in terms of energy store compared with hypothermic perfusion, whereas the latter appeared to have a risk of possible myocardial damage caused by the perfusion itself.

Relations of preoperative hemodynamics and coronary blood flow to improved left ventricular function after valve replacement for aortic regurgitation

In this study of the limits of reversibility of left ventricular function after aortic valve replacement for aortic regurgitation, measurements were made of pre- and postoperative coronary blood flow and left ventricular volumes. Eighteen patients who had undergone aortic valve replacement for pure aortic regurgitation using the Björk-Shiley valve or the Bicerval valve were restudied an average of 8 +/- 3 months after surgery. Postoperative left ventricular end-systolic and end-diastolic volumes returned to near normal values. The slight left ventricular wall thickening apparent before surgery remained unchanged after surgery and, consequently, left ventricular mass, though somewhat reduced, remained abnormally high. Ejection fraction, which was low preoperatively, returned to normal postoperatively. Total coronary sinus blood flow decreased after surgery, but coronary sinus blood flow per 100 g of left ventricular mass increased. This recovery of coronary flow per unit mass was believed to cause the improvement in left ventricular function. A significant correlation was found between postoperative systolic function and preoperative left ventricular end-systolic and end-diastolic volumes, wall thickness and, especially, left ventricular mass, the latter indicating that, if preoperative left ventricular mass is less than 350 g/m2, postoperative improvement of systolic function is attainable. Another significant correlation was indicated by measurements of coronary sinus blood flow per 100 g of left ventricular mass. If this is greater than 35 ml/min before surgery, a postoperative improvement in systolic function to within the normal range may be expected.

A special role of the parvocellular red nucleus in lesion-induced spontaneous tremor in monkeys

The neural mechanisms underlying spontaneous tremor were investigated in monkeys. Tremor-producing ventromedial tegmental (VMT) lesions involve at least three major neural elements. (1) Parvocellular division of the red nucleus (RNpc); (2) cerebellothalamic fibers passing through the red nucleus, and, (3) nigrostriatal fibers. These three elements were destroyed stereotaxically in areas remote from the VMT area separately and/or in various combinations, and correlation between the site of lesions and tremor was made. Lesion-induced tremor appeared only when the three elements were destroyed. A possible, particular role of the RNpc in the production of the spontaneous tremor is discussed.

[The mechanism of the increase in the serum CA125 concentration in patients with endometriosis]

We discussed the mechanism of the increase in CA125 among patients with benign gynecologic diseases, especially with endometriosis. The tissue CA125 concentrations of surface endometrium in patients with adenomyosis were as follows; the highest tissue concentration was observed at the early proliferative phase followed by the late secretory one and was lowest in the late proliferative one. The tissue CA125 concentration showed the significantly different characteristics in surface and ectopic endometrium. The increase in CA125 in the intraperitoneal fluids was observed among cases of early pregnancy, acute appendicitis and ovarian hyperstimulation syndrome (OHSS). Tissue samples from both the peritoneum obtained from patients with acute appendicitis and the cyst wall obtained from OHSS cases showed a high concentration of tissue CA125. From these findings, it was suggested that one of the causes of serum CA125 increase in patients with adenomyosis appeared to be the increase in the ectopic endometrial tissues in the myometrium and direct shedding from ectopic endometrial cells into peripheral circulation. On the other hand, in patients with chocolate cysts, the increase in serum CA125 was suppressed because it was secreted into the inside of the chocolate cyst. The production of CA125 may take place not only from ectopic endometrial cells of adenomyosis but also from the peritoneal tissues of patients with acute appendicitis.

Effect of lung resection on blood lactate threshold in lung cancer patients

We studied the effect of a decrease in vital capacity (VC) on the blood lactate threshold detected during exercise in 16 preoperative (PRE) and 10 postoperative (POST) lung cancer patients who had undergone lobectomy or pneumonectomy. The PRE patients were selected on the basis of having normal preoperative pulmonary function. The POST patients were selected on the basis of having normal preoperative pulmonary function and a postoperative VC of less than 80%. The oxygen consumption/body surface area at a 2.2 m.mol.l-1 arterial lactate concentration (VO2/BSA at La-2.2) was adopted as the blood lactate threshold. VC/BSA in the POST group significantly correlated with VO2/BSA at La-2.2 (r = 0.85, P less than 0.01), but not in the PRE group. SaO2 at La-2.2 was 95.4 +/- 1.5% in the PRE group and 95.2 +/- 1.3% in the POST group. SaO2 at La-2.2 did not correlated with VC/BSA in either group. The hemoglobin concentration (Hb) in the arterial blood correlated significantly with VC/BSA in the POST group (r = 0.65, P less than 0.05) but not in the PRE group. These results indicate that VO2/BSA at La-2.2 was restricted by VC in patients with restrictive pulmonary function disorder. Of the three elements of oxygen delivery, Hb was a limiting factor for VO2/BSA at La-2.2 but SaO2 was not. Cardiac output, which was not measured in our study, was speculated to be another limiting factor for VO2/BSA at La-2.2.

Diaphragm function after pulmonary resection. Relationship to postoperative respiratory failure

We studied the lung mechanics and respiratory muscle function in 20 patients undergoing pulmonary resection. Transdiaphragmatic pressure (delta Pdi) during quiet breathing did not show any remarkable change after the operation (9.5 +/- 1.1 to 10.9 +/- 1.0 cm H2O), while the ratio of abdominal to transdiaphragmatic pressure changes (delta Pab/delta Pdi) revealed a significant difference between the preoperative and the early postoperative periods (0.32 +/- 0.06 to 0.00 +/- 0.11, p less than 0.05). The postoperative delta Pab/delta Pdi correlated significantly with the work of breathing (r = -0.60, p less than 0.01). The maximal transdiaphragmatic pressure (Pdimax) decreased significantly after operation (75.0 +/- 15.8 to 32.8 +/- 12.4 cm H2O, p less than 0.05), with no significant change in the maximal inspiratory mouth pressure (MIP) (74.2 +/- 16.8 to 39.5 +/- 11.6 cm H2O). Four of 20 patients developed respiratory failure postoperatively and required mechanical ventilation. delta Pab/delta Pdi in these patients was significantly lower than in the other patients (-0.62 +/- 0.24 versus 0.16 +/- 0.09, p less than 0.005). Our results suggested that during quiet breathing diaphragmatic function was preserved and intercostal/accessory muscles recruitment increased, but maximal strength of the diaphragm might be reduced in patients undergoing pulmonary resection.

Urinary excretion of 3-methylhistidine as an index of protein nutrition in total parenteral nutrition

In 39 healthy adult volunteers and nine patients receiving total parenteral nutrition (TPN), determinations were made of the urinary excretion of 3-methylhistidine (3-Mehis) to estimate the degree to which the urinary output of 3-Mehis reflects the status of protein nutrition. In 19 males and 10 females of the former group, measurements were made of the amount of 3-Mehis and of creatinine (Cr) in 24-hr urine samples. The urinary output of 3-Mehis was also measured in two subgroups of five healthy adult male subjects who were fed one of the two different diets prescribed: meat (M) and meat-free (F) diet. Furthermore, in one of these subgroups which was fed on F diet, the urinary output of 3-Mehis was measured both while the subject was kept at bed rest and while the subject was allowed to live a normal life. From these measurements the standard value was determined for the urine 3-Mehis level and the 3-Mehis/Cr ratio in 24-hr urine in healthy adult human subjects of both sexes. In nine patients maintained on TPN these indices of nutritional status were measured before and at 4 weeks of TPN. The time course of the indices was also investigated. The results obtained suggest that both the urinary output of 3-Mehis and the 3-Mehis/Cr ratio can provide a sensitive index of the status of protein nutrition.