Characteristics of electrocardiographic changes with some representative antiarrhythmic drugs in adult rats

The characteristics of ECG changes with representative antiarrhythmic drugs; procainamide (PA) (class Ia), lidocaine (LC) (class Ib), propranolol (PN) (class II), and verapamil (VP) (class IV) were investigated in adult rats. Action potential (AP) was also recorded from myocardial cells during electrical stimuli with frequencies of 1-5 Hz. All the four drugs produced ECG abnormalities which contained AV and SA blocks at middle and high dose levels. Three drugs except VP induced a prolongation of QRS complex and notched QRS at low or middle dose level. As compared such effects with those in dogs and humans, some differences were noted as follows: (1) a dose-dependent prolongation of QT interval by LC and PN, and (2) a shortening of RR interval by VP at the dose of 0.6 mg/kg or less. LC and PN elongated the QT interval in the unipolar precordial chest lead ECGs at right anterior chest positions. These two drugs did not affect the duration of AP (APD90), whereas maximum upstroke velocity (Vmax) decreased. These results suggest that the prolongation of QT interval with LC and PN was due to a delay in local ventricular conduction time, especially on the right ventricle. The shortening of RR interval by VP was clearly blocked by the pretreatment with PN, indicating that this shortening reflected the sympathetic nervous reflex presumably due to the peripheral vasodilation effect of VP.

Evaluation of valvular heart disease with cine gradient echo magnetic resonance imaging

Electrocardiographic referenced repetitive gradient echo magnetic resonance imaging (cine GRE) has been used to detect and quantify valvular regurgitation. Regurgitation is recognized as a signal void in the high intensity blood pool on these images. Mitral regurgitation causes a signal void in the left atrium in systole, and aortic regurgitation produces one in the left ventricle in diastole. The specificity, sensitivity, and diagnostic accuracy of cine GRE for the detection of mitral and aortic regurgitation was greater than 0.93, 0.89, and 0.92, respectively. The severity of regurgitation has been quantified as the difference in the stroke volume between the two ventricles by measuring the volume of the blood pool, as shown in the stack of magnetic resonance tomograms. Severity has also been assessed by measuring the volume of the signal void. Finally, measurements of the volume of aortic regurgitation have recently been achieved by using velocity-encoded cine GRE. This technique provides a direct measurement of retrograde flow in the aorta during diastole. New cine GRE imaging techniques provide a noninvasive means for quantification of valvular as well as ventricular function.

Molecular cloning of a porcine gene syk that encodes a 72-kDa protein-tyrosine kinase showing high susceptibility to proteolysis

By using antibodies raised against a portion of N terminus of 40-kDa kinase (Kobayashi, T., Nakamura, S., Taniguchi, T., and Yamamura, H. (1990) Eur. J. Biochem. 188, 535-540), not only 40-kDa protein but also 72-kDa protein were detected on immunoblot analysis of porcine spleen homogenate. In splenocytes preparation, the antibodies could immunoprecipitate protein-tyrosine kinase activity of the 72-kDa protein but not detect the 40-kDa protein even on immunoblot. After incubation of crude spleen homogenate at 37 degrees C with or without various protease inhibitors, immunoblot analysis revealed proteolytic breakdown of the 72-kDa protein to 40-kDa fragment. Next, using oligonucleotides designed according to partially sequenced information of the 40-kDa kinase as a probe, we have isolated a clone containing entire coding sequence for the 40-kDa kinase from a porcine spleen cDNA library. This clone had a 1884-base-pair-long open reading frame encoding 628-amino-acid polypeptide with a calculated molecular weight of 71,618. The deduced amino acid sequence did not contain a ligand binding or membrane spanning region but did a well-conserved protein-tyrosine kinase domain and two src homology region 2 domains. The sequences of these domains showed 30-40% identity to those of other protein-tyrosine kinases, but those of remaining parts were quite unique. From these results, we concluded that the 40-kDa kinase was generated by proteolysis from the 72-kDa holoprotein which was a new member of nonreceptor protein-tyrosine kinase so far reported. We therefore designated this gene as syk after spleen tyrosine kinase.

Suppression of ovarian activity during the breeding season in suckling Japanese monkey (Macaca fuscata)

The menstrual cycle was examined in Japanese monkeys, short-day breeders, with or without nursing babies during the breeding season by determining the change in the plasma concentration of progesterone. Blood samples were obtained weekly from suckling and nonsuckling mothers for 6 months from September to February. Plasma concentrations of progesterone in suckling mothers did not show any apparent fluctuation and remained low throughout the study, while irregular menstruation was observed. In nonsuckling mothers, cyclic changes in plasma progesterone concentration accompanied by regular menstruation occurred from October. Annual birth rates were lower in monkeys housed in individual cages (17.6%) than in free-ranging monkeys in Miyajima colony, near Hiroshima in Japan (37.5%). These results indicate that the suckling stimulus for females with young born in spring is potent enough to suppress ovarian activity during the autumn breeding season.

Evaluation of right ventricular early diastolic filling by cine nuclear magnetic resonance imaging in patients with hypertrophic cardiomyopathy

Numerous studies have established abnormalities in systolic and diastolic function of the left ventricle in hypertrophic cardiomyopathy. A consistent feature of this disease is reduced diastolic function of the left ventricle, but little information is available regarding right ventricular function in this disease. Cine nuclear magnetic resonance (NMR) imaging has been found to be effective for measuring right ventricular volumes and therefore was used to assess early diastolic filling of the right ventricle in patients with hypertrophic cardiomyopathy. Right ventricular time-volume curves were obtained from cine NMR images in 10 patients with hypertrophic cardiomyopathy and 8 normal subjects. Right ventricular volume was calculated with use of Simpson's algorithm at approximately 18 phases of the cardiac cycle and, from the curve, peak filling rate and filling fraction during the first third of diastole were determined. In patients with hypertrophic cardiomyopathy, peak filling rate tended to be less (176 +/- 46 vs. 305 +/- 50 ml/s, p less than 0.01) and filling fraction decreased (39.5 +/- 13.8 vs. 74.5 +/- 13.3%, p less than 0.01) in comparison with values in normal subjects. Thus, analysis of right ventricular time-volume curves obtained by using cine NMR imaging demonstrated diastolic dysfunction of the right ventricle in hypertrophic cardiomyopathy.

[Effect of X-rays combined with ACNU and O6-ethylguanine on rat subcutaneous gliomas]

Rat gliomas of subcutaneously transplanted RGc-6 cells were irradiated with X-ray either alone, or combined with ACNU, and the cell-survival was assayed in vitro. Cell-survival curve composed of two components by X-irradiation alone indicated the presence of a hypoxic cell fraction. We have previously shown that combined treatment with ACNU apparently made the effect of X-ray on spheroids in vitro of the same cell line of RGc-6 more powerful. Although treatment of rat gliomas with ACNU administered at 2 hrs prior to X-irradiation was most effective, it resulted in only the additive effect of the independent action of the two agents. Further treatment by O6-ethylguanine prior to ACNU administration and X-irradiation apparently increased the strength of the effect of ACNU combined with X-ray to the dose-modifying factor for X-ray of 1.8. The result indicated that the combination of O6-ethylguanine prior to ACNU administration and X-irradiation may clinically enhance the effect of X-ray against apparent ACNU-resistant glioma cells such as RGc-6 cells.

Expiratory muscle fatigue in normal subjects

We examined expiratory muscle fatigue during expiratory resistive loading in 11 normal subjects. Subjects breathed against expiratory resistances at their own breathing frequency and tidal volume until exhaustion or for 60 min. Respiratory muscle strength was assessed from both the maximum static expiratory and inspiratory mouth pressures (PEmax and PImax). At the lowest resistance, PEmax and PImax measured after completion of the expiratory loaded breathing were not different from control values. With higher resistance, both PEmax and PImax were decreased (P less than 0.05), and the decrease lasted for greater than or equal to 60 min. The electromyogram high-to-low frequency power ratio for the rectus abdominis muscle decreased progressively during loading (P less than 0.01), but the integrated EMG activity did not change during recovery. Transdiaphragmatic pressure during loading was increased 3.6-fold compared with control (P less than 0.05). These findings suggest that expiratory resistive loaded breathing induces muscle fatigue in both expiratory and inspiratory muscles. Fatigue of the expiratory muscles can be attributed directly to the high work load and that of the inspiratory muscles may be related to increased work due to shortened inspiratory time.

Seasonal changes in plasma concentrations of immunoreactive inhibin and testicular activity in male Japanese monkeys

Seasonal changes in plasma immunoreactive (ir-) inhibin, testosterone, LH, and FSH concentrations were examined in five sexually mature male Japanese monkeys (Macaca fuscata fuscata) housed indoors individually, to explore the reproductive cyclicity in the male. Blood samples were collected monthly throughout one year, and testicular size, semen volume, and number of sperm in the semen were ascertained at the same time in the same animals. Semen samples were obtained by penile electrostimulation. The results showed a clear seasonal increase in all parameters: plasma ir-inhibin, testosterone, testicular size, semen volume, and total number of sperm in the liquid portion of the semen during the autumn and winter months in synchrony with the natural breeding season. In contrast, plasma LH and FSH remained unchanged throughout the year, although plasma FSH tended to increase during the breeding season concomitant with an increase in plasma ir-inhibin. A significant positive correlation between FSH and ir-inhibin was observed in two of five monkeys. The positive correlations between plasma ir-inhibin and testicular activities during both the developing and regressing phases of the testicular cycle indicate that plasma ir-inhibin is a useful indicator of testicular activity as well as an indicator of Sertoli cell function in the Japanese monkey.

A case of Behçet's disease with a rapidly enlarging aneurysm in the common carotid artery

A 16-year-old boy had incomplete Behçet's disease with common carotid artery aneurysm and an ulcer in the transverse colon. To our knowledge, this complication in the carotid artery has been previously reported in only 6 cases. Arterial repair and high-dose corticosteroid therapy (pulse therapy) were successful.

Vascular effects of betaxolol, a cardioselective beta-adrenoceptor antagonist, in isolated rat arteries

The effects of betaxolol on isolated rat arteries and the modes of action were investigated. Betaxolol (10(-5)-10(-3) M) relaxed the 80 mM K(+)-induced contraction of aortic strips concentration-dependently. The 50% inhibitory concentration of betaxolol in the K(+)-induced contraction was 3 times higher than that of papaverine and about 3 times lower than that of bunitrolol. The relaxations by betaxolol were also demonstrated in renal, mesenteric and femoral arteries. Betaxolol (3 x 10(-6) M-10(-4) M) produced rightward parallel shifts of the concentration-response curves for Ca2+ in the K(+)-depolarized aortic strips. On the other hand, betaxolol produced downward shifts as well as rightward shifts of the concentration-response curves for norepinephrine, 5-HT and angiotensin II. In K(+)-depolarized aortic strips, the cytosolic Ca2+ concentration measured with a fluorescent indicator, fura-2, was decreased by betaxolol (10(-4) M) almost concomitantly with the loss of tention. An elevation of external Ca2+ from 2.5 mM to 10 mM restored both the cytosolic Ca2+ concentration and tention. The relaxations of arteries induced by betaxolol were not influenced by glybenclamide, methylene blue, indomethacin or removal of the endothelium. These results suggest that betaxolol possesses a direct vasodilating action, and the action may be due to the inhibition of Ca2+ influx across the cell membrane.

Hierarchical regulation of interleukin production: induction of interleukin 6 (IL-6) production from bone marrow cells and marrow stromal cells by interleukin 3 (IL-3)

IL-3 stimulated the production of IL-6 from a bone marrow-adherent cell population, macrophages and from hemopoietic supportive stromal cell lines. It also induced IL-6 production from a stem cell-enriched population of bone marrow cells which did not produce IL-6 without stimulation. In contrast, stimulation with IL-6 of all the cell populations studied in the present experiments did not induce IL-3 production. These results indicate a hierarchical network in the regulation of interleukin production, and existence of a positive feedback mechanism; IL-3 induces IL-6 production which in turn stimulates stem cells into cycle and induces stem cells to respond to IL-3.

Prevention of genetic resistance to bone marrow allografts by reticuloendothelial system blockade

Agents which are toxic to macrophages such as silica and caragheenan suppress genetic resistance to bone marrow allografts. However, these agents may also be toxic to other tissues and cannot be used for the establishment of long-term bone marrow chimerism. In this study, we used chemically insert carbon particles to blockade phagocytic cells, and succeeded in carrying out bone marrow allografts. Long-term survival of the recipient mice after bone marrow transplantation (BMT) was achieved without apparent evidence of graft-versus-host reaction (GVHR), although T-cells were not depleted in donor marrow cells. The hemopoietic system of the recipient mice was replaced by that of donor origin. These results indicate that phagocytic cells play an essential role, probably as effector cells in genetic resistance to bone marrow allograft.

[Twenty-eight-day repeated dose toxicity test of p-phenetidine in F344 rats]

A twenty-eight-day repeated dose toxicity test of p-phenetidine was carried out in male and female F344 rats at dose levels of 160, 40, 10 or 0 mg/kg/day. Thirty animals of both sexes were divided into 6 groups of equal number. All groups were treated daily by i.g. administration for 28 days, two extra groups of animals at dose levels of 160 and 0 mg/kg being used for investigation of recovery over 14 days. Hematological and urinary examinations revealed decrease in erythrocytes and increased serum reticulocytes and urinary urobilinogen in the 160 and 40 mg/kg groups of both sexes, and methemoglobinemia occurred in the 160 mg/kg group. Increase in spleen weight was noted in the 160 and 40 mg/kg groups. On histopathological examination, hemosiderosis, increased extramedullary hemopoiesis, congestion of the spleen and myeloid hyperplasia of the bone marrow were observed in the 160 and 40 mg/kg groups of both sexes. Repair of these lesions occurred within 14 days after the cessation of administration. Based on these findings, a no-observed-effect level for p-phenetidine would be concluded 10 mg/kg/day.

Determination of left ventricular volume and mass with use of biphasic spin-echo MR imaging: comparison with cine MR

In this study, the authors compared a new rapid spin-echo magnetic resonance (MR) imaging method, biphasic MR, with cine MR in the determination of left ventricular volume and mass in healthy volunteers. Biphasic spin-echo MR images covering the entire heart were obtained with use of the electrocardiogram R wave and the downslope of the T wave at both end diastole and end systole, respectively. Biphasic MR-determined values correlated well with small standard errors of the estimate (end-diastolic volume = 7.82 cm3, end-diastolic mass = 10.20 g, end-systolic mass = 10.08 g, ejection fraction = 2.62%) and were more reproducible. Cine MR-defined end-systolic volume was significantly larger (P less than .01) and ejection fraction was significantly smaller (P less than .005) than biphasic MR-determined values probably because of the uncertainty in isolating end systole with cine MR. Left ventricular volumes, mass, and ejection fraction are more accurately and reproducibly quantified in a more time-efficient manner with use of biphasic MR than with cine MR because of its significantly shorter image acquisition and reconstruction times.

Carcinosarcoma of the submandibular gland. An autopsy case

We present a rare case of submandibular gland carcinosarcoma occurring in a 45-year-old male patient. His clinical history revealed that the carcinosarcoma had developed from a carcinoma ex mixed tumor in three years. In spite of repeated resection, intensive chemotherapy and irradiation, the tumor recurred and grew rapidly, and the patient died of hemothorax caused by rupture of a pulmonary metastatic tumor. The fourth recurrent tumor and autopsy specimens showed features of carcinosarcoma consisting of three tumor components, i.e., undifferentiated carcinoma, and chondrosarcomatous and osteosarcomatous growth. The metastatic nodules in both lungs and pulmonary hilar lymph nodes showed the same pattern. Immunohistochemically, the chondrosarcomatous cells were positive for vimentin and S-100 protein, and for epithelial markers such as epithelial membrane antigen (EMA) and cytokeratin (MA-902). Undifferentiated carcinoma cells, on the other hand, were partially positive for muscle actin other than cytokeratin (KL 1). Ultrastructurally, desmosome-like structures were seen in the chondrosarcomatous cells. These findings suggest that the sarcomatous lesions might have originated from epithelial cells.

Cysteine protease in bovine milk capable of hydrolyzing casein as the substrate and elevation of the activity during the course of mastitis

Cysteine protease was found to be present in bovine milk that catalyzed casein as the substrate. The protease was activated by reducing agents such as 2-mercaptoethanol and inhibited by monoiodoacetic acid, but not affected by the addition of phenylmethylsulfonyl fluoride, calcium or ethylene glycol bis (beta-aminoethyl)-N,N,N',N'-tetraacetic acid. The protease activity was linear as a function of protein amount and incubation time, and showed maximum at pH 6.0. By Sephacryl S-200 chromatography, at least two types of cysteine proteases having molecular weights of 45 kDa and more than 150 kDa were detected. The activity was increased in mastitic milk, and well correlated with the stages of mastitis, as indicated by the California mastitis test, somatic cell count and protein concentration. These results suggested that cysteine protease(s) is involved in the pathogenesis of mastitis.

Pathology of excessive iron storage in the Afghan pika (Ochotona rufescens rufescens)

Iron deposition in the tissues of 30 Afghan pikas (Ochotona rufescens rufescens) was examined histopathologically. In all cases, iron deposits were present in the liver and in two-thirds of cases, there was portal fibrosis with tissue injury. In animals, in general, tissue injury induced by iron overload is usually mild and only in a few exceptional species does hepatic haemochromatosis occur. Thus, Afghan pikas are a rare example of reaction to iron overloading.

Follow-up study on ruptured aneurysms treated by wrapping

The authors experienced 1903 cases of ruptured aneurysm between 1961 and 1986. Most cases were treated by clipping or ligating the aneurysmal neck. However, these procedures were impossible in 52 cases (2.7%), for which wrapping alone (21 cases), aneurysmal body clipping and wrapping (11 cases), or body ligation and wrapping (20 cases) was performed. We studied the long-term results in 44 of these 52 cases. Rerupture occurred in only two cases with incomplete wrapping. We concluded that complete wrapping, and wrapping of residual portions following aneurysmal body clipping or body ligation produce favorable results.