Comparative influence of load versus inotropic states on indexes of ventricular contractility: experimental and theoretical analysis based on pressure-volume relationships

We examined the quantitative influence of carefully controlled alterations in end-diastolic volume and afterload resistance on multiple simultaneously determined ejection and isovolumetric phase indexes of left ventricular contractile function in 23 isolated supported canine ventricles. The influence of load change on each index was compared with its sensitivity to inotropic stimulation, and this sensitivity was in turn contrasted to the response of the end-systolic pressure-volume relationship (ESPVR). Experimental data demonstrated various degrees of load sensitivity among the indexes, with a generally curvilinear relationship between load and index response for both preload and afterload alterations. The curvilinear nature of these relationships meant that over a select range of loading, many indexes demonstrated relative load independence. They also often displayed greater sensitivity to inotropic change than the ESPVR, and both factors help explain their enduring clinical utility. To further explore the influence of load and contractile state on several of the indexes, we developed a theoretical analysis, using variables common to pressure-volume relationships, in which these dependencies could be derived. The theoretical models fit very well with the experimental data, and reaffirmed the frequently curvilinear nature of the relationships. We conclude that while many clinical indexes of ventricular contractile function show significant load dependence, the information they provide can be reasonably interpreted within defined ranges of load and inotropic alteration. Any advantage of the ESPVR will derive not from the magnitude of its response to inotropic change, which is smaller than most other indexes, but from its relative insensitivity to load alteration over a wider range of load.

A case with bronchogenic cyst diagnosed by reconstruction CT prior to surgery which showed cardiac abnormalities

A case report of a patient with bronchogenic cyst who presented with cardiogenic symptoms was described. The precise diagnosis was finally made after completing various diagnostic procedures which included reconstruction computed tomography. The patient, a 30-year-old man, was admitted to our hospital because of palpitation, chest pain and fever of three weeks duration. An electrocardiogram (ECG) revealed evidence suggestive of left atrial overloading and frequent atrial premature beats. A chest roentgenogram showed an abnormal shadow behind the right upper portion of the heart and a cross-sectional echocardiogram revealed abnormal echoes with ill-defined margins in the left atrium. Computed tomography (CT) revealed the presence of the left atrial tumor but left atriography suggested that it was extracardiac and compressing the left atrium. Reconstruction CT was therefore performed and the cyst was diagnosed as being in a subcarinal position. A mobile calcified mass was also demonstrated by the CT. An operation was performed and a cyst, 6 X 3 cm, was removed almost completely and a histopathological diagnosis of bronchogenic cyst was made. In this particular case, ECG abnormalities which suggest atrial damage and the diagnostic usefulness of reconstruction CT are stressed.

The use of left ventricular end-ejection pressure and peak pressure in the estimation of the end-systolic pressure-volume relationship

The end-systolic pressure-volume relationship (ESPVR) as derived from left ventricular pressure-volume loops has gained increasing acceptance as an index of ventricular contractile function. In animal experiments the ESPVR has been defined as a line connecting the upper left corners of several differently loaded pressure-volume (P-V) loops with a slope parameter Ees and a volume axis intercept parameter Vo. In the clinical setting, several variants of the ESPVR have been determined with use of peak left ventricular pressure, end-ejection pressure, and end-ejection volume. The maximum P-V ratio has also frequently been measured. We attempted to determine which of these alternatives resulted in good approximations of the reference ESPVR in eight isolated canine ventricles that ejected into a simulated arterial impedance system with resistance, compliance, and characteristic impedance. We determined various versions of the ESPVR from the same set of beats quickly obtained with little change in inotropic background. To vary ventricular pressure wave forms, each of the arterial impedance parameters was independently controlled at 50%, 100%, and 200% of normal. Against each of the nine combinations of the impedance parameters four P-V loops were obtained under four preloads and from each of the sets of four P-V loops, the reference ESPVR, linear regression of the peak pressure on end-ejection volume (ESPVRPP-EEV), and linear regression of end-ejection pressure on end-ejection volume (ESPVREEPV) were determined. In addition, the maximum P-V ratio (MPVR) was calculated for each P-V loop.(ABSTRACT TRUNCATED AT 250 WORDS)

[Measurement of 5'-deoxy-5-fluorouridine (5'-DFUR) by high-performance liquid chromatography and studies on pharmacokinetics of 5'-DFUR and 5-fluorouracil by oral and intravenous administration]

The authors have made clear that 5'-deoxy-5-fluorouridine (5'-DFUR), a derivative of 5-fluorouracil (5-FU), is activated by thymidine phosphorylase with has a particularly high activity in human malignant tumors. This derivative therefore, has fewer side-effects and can be expected to produce a greater antitumor effect when administered to cancer patients. Blood levels of 5'-DFUR and 5-FU were then observed with time after oral or intravenous 5'-DFUR administration in order to study its clinical effect. First, a method for measurement of 5'-DFUR and 5-FU was devised using high-performance liquid chromatography (HPLC). The results obtained using this method revealed that for intravenous administration both 5'-DFUR and 5-FU showed rapid drops in blood level while for oral administration both showed blood level peaks after one hour which were maintained of the same level for two hours, decreasing gradually thereafter. 5-FU showed a blood level peak after one hour, decreasing gradually thereafter. From the above results it was proved that a relatively high percentage of orally administered 5'-DFUR was absorbed from the intestine.

[Enzymatic conversion of tegafur in human tumor tissue]

Enzymatic conversion of tegafur was studied using a thymidine phosphorylase preparation purified from human liver cancer. Tegafur dissolved in water slowly decomposed to 5-FU upon storage at 37 degrees C and this conversion was further activated with an addition of a thymidine phosphorylase preparation. Analysis of Tegafur and 5-FU was performed on a high performance liquid chromatograph. The Km value was in agreement with Michaelis-Menten Kinetics and 2.44 X 10(-2) M without thymidine phosphorylase preparation. When the preparation was added, it was 2.53 X 10(-4) M and 1.75 X 10(-3) M, respectively. Determination of 5-FU concentrations in blood, normal and tumor tissues following a long term administration of Tegafur was performed. The highest concentration of 5-FU was detected in tumor tissue followed by normal tissue and blood, suggesting a human liver thymidine phosphorylase was capable of converting Tegafur to 5-FU more actively in tumor tissue than in normal tissue.

Isolation and pathogenicity of provisional serovar 1621-54 of "Shigella" from imported cynomolgus monkeys

The provisional serovar 1621-54 of "Shigella" was isolated from 36 (13.2%) of 273 cynomolgus monkeys newly imported into Tsukuba Primate Center for Medical Science (TPC) from Indonesia during the period from 1980 through 1981. The biochemical properties of the isolates were in good agreement with those of previously described provisional "Shigella" serovar 1621-54. Clinically, 13 (36.1%) of 36 monkeys being positive for the organisms excreted diarrheal stools on arrival at TPC. In addition, the organisms were isolated also from three other monkeys contracting dysentery during the quarantine period at TPC. One of them died 2 days after the onset of dysentery. Histopathological findings of this case were essentially the same as those of Shigella-infected monkeys. Pathogenicity of the isolates was examined in three experimental infection models; (1) the infection model using cultured HeLa-S3 cells, (2) the keratoconjunctival infection model of the guinea pig, and (3) the intestinal infection model of the cynomolgus monkey. All the strains tested showed positive results in these experimental models, causing intracellular penetration and multiplication in HeLa-S3 cell cultures, keratoconjunctivitis in guinea pigs, and dysentery in cynomolgus monkeys. These results indicate that provisional "Shigella" serovar 1621-54 is a causative agent of dysentery in man as well as in monkeys.

[Evaluation of the optimum method of administration of a new antineoplastic agent, HCFU, based on the serum 5-FU concentration following oral administration]

The serum concentration of HCFU and its metabolites was clinically studied to obtain the most useful information for optimal methods of oral administration of a new anticancer agent. In this paper, the serum level of the only 5-FU among metabolites of HCFU was discussed. High-performance liquid chromatography was used as monitoring the agent. The serum level of 5-FU usually reached a maximum one hour after oral administration of 200mg HCFU and remained more than 0.2 to 0.3 microgram/ml for at least two hours. When administered 200mg HCFU every 6 hours (800mg/day), the serum level of 5-FU could be maintained more than 0.1 micrograms/ml for 24 hours. When administered 200mg three times after each meal (600mg/day), its level could be maintained more than 0.1 microgram/ml only for daytime, but not at night. Consequently, we suggest that the most favorable therapeutic oral administration of HCFU might be 200 mg every 6 hours (800mg/day) to maintain the serum level of 5-FU over 0.1 microgram/ml for 24 hours.