Theiler's murine encephalomyelitis virus (TMEV): the role of a small out-of-frame protein in viral persistence and demyelination

Theiler's murine encephalomyelitis virus (TMEV) belongs to the genus Cardiovirus of the family Picornaviridae and is divided into two subgroups on the basis of different biological activities. GDVII subgroup strains produce acute and fatal polioencephalomyelitis in mice with no virus persistence. In contrast, DA or TO subgroup strains cause an early nonfatal polioencephalomyelitis. TMEV is thought to be an excellent animal model for the human demyelinating disease, multiple sclerosis. Data suggest that macrophages are a major reservoir harboring the virus. A small out-of-frame protein designated L* is synthesized in DA subgroup strains from an alternative, out-of-frame, initiation site. Studies of a DA mutant virus, having an ACG rather than an AUG and therefore does not synthesize L* protein, demonstrate that this protein is important for virus growth in particular cell types and is critical for DA-induced demyelinating disease and virus persistence. In addition, TMEV can be used as a vector for delivering foreign sequences into the central nervous system.

Development of a syngenic brain-tumor model resistant to chloroethyl-nitrosourea using a methylguanine DNA methyltransferase cDNA

Chloroethyl-nitrosourea (CENU) is one of the most potent chemotherapeutic agents for brain tumors. However, acquired resistance to this drug has become a serious problem in the treatment of brain tumor patients. The main mechanism of the resistance is a recruitment of the O6-methylguanine-DNA- methyltransferase (MGMT) in tumor cells. Many approaches, including treatment with enzyme-depletions, antibodies, antisenses, and a ribozyme, have been reported to successfully overcome the resistance. In order to evaluate these approaches properly, we designed a syngenic rat brain-tumor model resistant to CENU. The 9L rat gliosarcoma cells were retrovirally transduced with MGMT cDNA and stereotactically implanted into the brain parenchyma. In this model, rats inoculated with resistant cells died significantly earlier than did rats with control cells after treatment with CENU. Because of the limited intracranial space, the animals presented a restricted survival. Since the survival was sensitive and reproducible, this system may have a role in the evaluation of approaches to drug-resistant brain-tumors.

First systematic chiral syntheses of two pairs of enantiomers with 3,5-dihydroxyheptenoic acid chain, associated with a potent synthetic statin NK-104

First systematic chiral syntheses of two pairs of enantiomers with 3,5-dihydroxyheptenoic acid chain, associated with a potent synthetic statin NK-104 are reported. A pair of syn diol isomers (NK-104 and its enantiomer) was obtained efficiently by diastereomeric resolution. The synthesis of a pair of anti diol isomers (3-epimer and 5-epimer) was accomplished effectively by the asymmetric aldol reaction followed by anti stereoselective reduction as key steps. Their purity determinations were effected by chiral HPLC analysis.

Multiple sclerosis and measles virus

Epidemiological studies suggest that patients with multiple sclerosis (MS) are exposed to some infectious agent(s) before puberty. The presence of virus-induced demyelination in animal models indicates that demyelination can occur following the trigger of a virus infection. Data regarding the immunological abnormalities to measles virus (MV) and the presence of neurological complications induced by MV infection suggest that MV may be a causative agent of the demyelination observed in MS. Numerous virological studies (e.g., morphological observation, virus isolation, and the search for the MV gene) have been performed, though definite evidence identifying MV as the causative agent has not yet been obtained.

Expression of lymphotoxin gene inserted into Theiler's murine encephalomyelitis virus

Theiler's murine encephalomyelitis virus (TMEV) belongs to the Picornaviridae genus. DA subgroup strains of this virus induce early, non-fatal polioencephalomyelitis followed by demyelination in the spinal cord, with virus persistence. We investigated the use of DA strain as a vector for the introduction of a foreign gene into the central nervous system. Human lymphotoxin (LT) gene was inserted in the L region, the most upstream part of the polyprotein coding region of DA genome. Expression of LT was demonstrated by an immunoblot and an enzyme-linked immunosorbent assay on BHK-21 cells that were infected with the recombinant virus. In addition, the expressed LT showed cytotoxicity against L-929 cells.

Partial maze procedure is effective treatment for chronic atrial fibrillation associated with valve disease

The maze procedure may be performed in combination with valve operations to treat chronic atrial fibrillation associated with valve dysfunction. Although we initially used the modified Cox maze III procedure, a more limited partial maze procedure is now preferred because the left atrium might be considered as the electrical impetues for atrial fibrillation. In this study we compared the results of 30 patients (group I) who underwent the full biatrial modified Cox maze III and 20 (group II) patients the partial maze procedure. While the rates of restored sinus rhythm were the same in both groups at 6-month follow-up (I: 83.3%, vs II: 80%), the following advantages were noted in the patients undergoing the partial maze procedure: shorter operative times, lesser elevations of creatine phosphokinase, lower rate of blood transfusion, lower rate of junctional rhythm soon after the operation, and a higher P wave in those patients with restored sinus rhythm. The effectiveness of the partial maze procedure seems equal to that of the biatrial modified Cox maze III procedure for atrial fibrillation associated with valve disease. The partial maze procedure is simple and less invasive, and thus might be applied more frequently as an additional procedure to valve operations without additional risk.

Early induction of transforming growth factor-beta via angiotensin II type 1 receptors contributes to cardiac fibrosis induced by long-term blockade of nitric oxide synthesis in rats

We previously reported that the chronic inhibition of nitric oxide (NO) synthesis increases cardiac tissue angiotensin-converting enzyme expression and causes cardiac fibrosis in rats. However, the mechanisms are not known. Transforming growth factor-beta (TGF-beta) is a key molecule that is responsible for tissue fibrosis. The present study investigated the role of TGF-beta in the pathogenesis of cardiac fibrosis. The development of cardiac fibrosis by oral administration of the NO synthesis inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) to normal rats was preceded by increases in mRNA levels of cardiac TGF-beta1 and extracellular matrix (ECM) proteins. TGF-beta immunoreactivity was increased in the areas of fibrosis. Treatment with a specific angiotensin II type 1 receptor antagonist, but not with hydralazine, completely prevented the L-NAME-induced increases in the gene expression of TGF-beta1 and ECM proteins and also prevented cardiac fibrosis. Intraperitoneal injection of neutralizing antibody against TGF-beta did not affect the L-NAME-induced increase in TGF-beta1 mRNA levels but prevented an increase in the mRNA levels of ECM protein. These results suggest that the early induction of TGF-beta1 via the angiotensin II type 1 receptor plays a major role in the development of cardiac fibrosis in this model.

Arthropod-borne tularemia in Japan: clinical analysis of 1,374 cases observed between 1924 and 1996

Sixteen cases of tularemia transmitted by arthropods are used to characterize arthropod-borne tularemia in Japan. Arthropod-borne tularemia accounted for 1.2% of a total of 1,374 cases of tularemia observed between 1924 and 1996. The number of cases reported in Japan was low when compared with the number of cases reported in the United States. Arthropod-borne tularemia, however, is increasing and has reached 10.1% incidences during the last 16 yr. No arthropod-borne cases were reported prior to 1951. The occurrence of tularemia infection caused by contact with diseased hares was diphasic with the higher peak occurring during the winter, whereas the occurrence of arthropod-borne tularemia was common from spring to autumn. Among the 16 cases that we studied, 5 were initiated by tick-bites, 5 by the crushing of ticks found on domestic dogs, and 1 by an unidentified insect. In the remaining 5 cases, the vectors were not identified although arthropod bites were confirmed. These arthropod-borne cases were observed exclusively in the northeastern area of Honshu, the main island of Japan, and the age of patients ranged from 23 to 74 yr. The arthropod vectors associated with tularemia and factors influencing incidence of arthropod-borne tularemia in Japan are discussed.

L* protein of the DA strain of Theiler's murine encephalomyelitis virus is important for virus growth in a murine macrophage-like cell line

Strain GDVII and other members of the GDVII subgroup of Theiler's murine encephalomyelitis virus (TMEV) are highly virulent and cause acute polioencephalomyelitis in mice. Neither viral persistence nor demyelination is demonstrated in the few surviving mice. On the other hand, strain DA and other members of the TO subgroup of TMEV are less virulent and establish a persistent infection in the spinal cord, which results in a demyelinating disease. We previously reported that GDVII does not actively replicate in a murine macrophage-like cell line, J774-1, whereas DA strain productively infects these cells (M. Obuchi, Y. Ohara, T. Takegami, T. Murayama, H. Takada, and H. Iizuka, J. Virol. 71:729-733, 1997). In the present study, we used recombinant viruses between these strains of the two subgroups to demonstrate that the DA L coding region of DA strain is important for virus growth in J774-1 cells. Additional experiments with a mutant virus indicate that L* protein, which is synthesized out of frame with the polyprotein from an additional alternative initiation codon in the L coding region of TO subgroup strains, is a key determinant responsible for the cell-type-specific restriction of virus growth. L* protein may play a critical role in the DA-induced restricted demyelinating infection by allowing growth in macrophages, a major site for virus persistence.

Probucol improves endothelial-dependent relaxation and decreases vascular superoxide production in cholesterol-fed rabbits

Recent data indicate that hypercholesterolemia increases endothelial superoxide anion (.O2-) production, and that this diminishes the bioactivity of nitric oxide produced in the endothelium. Probucol, a drug commonly employed for treatment of hypercholesterolemia, has antioxidant properties and inhibits oxidation of low density lipoproteins in vitro. We tested the hypothesis that probucol would decrease vascular .O2- production and improve endothelium-dependent relaxations in cholesterol-fed rabbits. Rabbits were divided into four groups: 1) a control group fed a standard diet; 2) a probucol group fed a standard diet containing 0.3% probucol; 3) a hypercholesterolemic group fed a diet containing 0.5% cholesterol; 4) a hypercholesterolemia-probucol group fed a diet containing 0.5% cholesterol and 0.3% probucol. The cholesterol-rich diet markedly increased plasma total cholesterol level and lipid peroxidation in the plasma, as reflected by thiobarbituric acid-reactive substances (TBARS). This concentration of probucol did not lower plasma cholesterol, but markedly reduced TBARS in the plasma of cholesterol-fed rabbits. Aortic segments from cholesterol-fed rabbits produced 1.8-fold more .O2- (assessed by lucigenin-enhanced chemiluminescence) and decreased endothelium-dependent vascular relaxations to acetylcholine compared to vessels from normal rabbits. In cholesterol-fed rabbits, probucol treatment normalized both .O2- production and endothelium-dependent relaxations to acetylcholine. In control rabbits, probucol had no effect on either of these parameters. We conclude that probucol treatment may prevent .O2(-)-induced inactivation of endothelium-derived nitric oxide and reduce vascular oxidant stress via reducing the level of .O2-.

Preclinical evaluation of the Kyocera Gyro centrifugal blood pump for cardiopulmonary bypass

The Kyocera Gyro pump has been developed as a completely seal-less centrifugal pump to overcome the problems of the conventional centrifugal pumps. The Gyro pump is a double pivot bearing-supported centrifugal pump with several specific design features, including its eccentric inlet port. We investigated the feasibility of the Gyro pump for cardiopulmonary bypass (CPB) in a bovine model, comparing it with the BioMedicus pump (BP-80). Ten healthy calves (5: Gyro pump, 5: BP-80) underwent 6 h of mildly hypothermic CPB at approximately 33 degrees C. Both pumps provided more than 50 ml/kg/min without any incidents. The haemodynamics of both groups remained stable within the normal range. All haematology and biochemistry data demonstrated no significant differences between the two groups. However, values of plasma-free haemoglobin and lactate dehydrogenase were less throughout the experiments of the Gyro pump than those of the BP-80. To obtain flow equivalent to that of the BP-80, the Gyro pump needed less rotational speeds than the BP-80 (2749.7 +/- 233.3 versus 3170.6 +/- 300.8 rpm. p < 0.05). Less rotational speed in addition to the difference in operating principle may contribute to less blood damage during the CPB OF the Gyro pump. After pumping for CPB, no leakage or thrombus formation was observed in either pump. The present study indicated that the Kyocera Gyro pump can be applied as a centrifugal pump for CPB with the same performance as the BP-80 and with relatively less haemolysis than the BP-80.

Hemolytic effect of the secondary vane incorporated into the back side of the impeller

The hemolytic effect of the secondary vane system, the antithrombogenic structure incorporated into the back side of the impeller of the C1E3 Gyro pump, was investigated. Impellers with 0, 2, 3, and 4 secondary vanes and an additional impeller with 2 secondary channels were fabricated and incorporated into the C1E3 pump casings. Hemolysis tests were performed under cardiopulmonary bypass conditions (flow rate 4.5 L/min, total pressure head 350 mm Hg) using flesh bovine blood. The normalized indices of hemolysis (NIH) of the pumps with 0, 2, 3, and 4 secondary vanes and the pump with 2 secondary channels were 0.0797, 0.0866, 0.104, 0.157, and 0.0591, respectively. These results indicated that design of the impeller with 2 secondary channels, which was the original design of C1E3 Gyro pump, was less hemolytic than the design with secondary vanes. Additionally, the possibility of the secondary channel system for the impeller bottom was demonstrated favorably.

Human cytomegalovirus induces interleukin-8 production by a human monocytic cell line, THP-1, through acting concurrently on AP-1- and NF-kappaB-binding sites of the interleukin-8 gene

Cytomegalovirus (CMV) infection induced interleukin-8 (IL-8) gene transcription in a human monocytic cell line, THP-1 cells, leading to IL-8 secretion. The functional analysis of the IL-8 gene revealed that both AP-1- and NF-kappaB factor-binding elements were involved in conferring the responsiveness to CMV. Moreover, electrophoretic mobility shift assays demonstrated that CMV induced the formation of NF-kappaB and AP-1 complexes. These results suggest that CMV activates these transcriptional factors, resulting in IL-8 gene expression.

[The pathogenesis of postinfectious encephalomyelitis and polyradiculoneuritis]

The neurological syndromes are known to occur following microbial infections, most of which are viral infections. Most patients recover uneventfully from such infections. Rarely, a serious postinfectious neurological syndrome develops presumably as an idiosyncratic reaction to the primary infection. The pathomechanisms of these syndromes are thought to be immune-mediated, because the etiologic microbe cannot be directly demonstrated, and because the pathological findings are highly similar to those found in experimental allergic encephalomyelitis and neuritis. The immunopathogenesis involves diverse interactions between a virus, the nervous system, and the immune response. All of the basic elements of the immune system, including humoral and cellular immunity, are involved in the pathogenesis. Novel concepts of the immune-mediated mechanisms are discussed, i.e., anti-idiotypic antibody, molecular mimicry, superantigens, heat shock proteins, and immunomodulations by viral proteins. The exact pathomechanism is, however, still to be elucidated.

A pivot bearing-supported centrifugal pump for a long-term assist heart

A pivot bearing-supported centrifugal blood pump has been developed. It is a compact, cost effective, and anti-thrombogenic pump with anatomical compatibility. A preliminary evaluation of five paracorporeal left ventricular assist studies were performed on pre-conditioned bovine (70-100 kg), without cardiopulmonary bypass and aortic cross-clamping. The inflow cannula was inserted into the left ventricle (LV) through the apex and the outflow cannula affixed with a Dacron vascular graft was anastomosed to the descending aorta. All pumps demonstrated trouble free performance over a two-week screening period. Among these five studies, three implantations were subjected for one month system validation studies. All the devices were trouble free for longer than 1 month. (35, 34, and 31 days). After achieving one month studies, all experiments were terminated. There was no evidence of device induced thrombus formation inside the pump. The plasma free hemoglobin levels were within normal ranges throughout all experiments. As a consequence of these studies, a mass production model C1E3 of this pump was fabricated as a short-term assist pump. This pump has a Normalized Index of Hemolysis of 0.0007 mg/100L and the estimated wear life of the impeller bearings is longer than 8 years. The C1E3 will meet the clinical requirements as a cardiopulmonary bypass pump. For the next step, a miniaturized pivot bearing centrifugal blood pump P1-601 has been developed for use as a permanently implantable device after design optimization. The evolution from C1E3 to the PI-601 converts this pivot bearing centrifugal pump as a totally implantable centrifugal pump. A pivot bearing centrifugal pump will become an ideal assist pump for the patients with failing heart.

Central role of vascular smooth muscle hyperreactivity in coronary hyperconstriction after balloon injury in miniature pigs

BACKGROUND

Coronary constrictive responses to autacoids become augmented 1 week after balloon injury in our swine model. The present study aimed to elucidate the mechanisms of this effect.

METHODS

In 12 hypercholesterolaemic miniature pigs, the coronary constrictive response to serotonin was examined angiographically 1 week after injury. After the angiographic study, organ chamber experiments using excised coronary artery were performed to clarify whether functional changes in endothelial cells or in vascular smooth muscle cells contributed to the hyperconstriction.

RESULTS

The coronary constrictive response to serotonin in vivo was significantly greater at the previously injured site than at the non-injured site. The degree of the hyperconstriction at the previously injured site exceeded that predicted from a geometric theory. Histological examination demonstrated that the previously injured site was almost covered with regenerated endothelial cells. In vitro studies demonstrated that serotonin caused significantly greater contraction in coronary artery strips, whether with or without endothelium, from the previously injured site than in those from the non-injured site. Endothelium-dependent relaxation in response to serotonin was comparable at the injured and non-injured sites.

CONCLUSIONS

These results suggest that the coronary hyperconstriction response to serotonin 1 week after injury results primarily from hyperreactivity of vascular smooth muscle. Whereas any contribution of endothelial dysfunction or the geometric effect may be minimal.

Theiler's murine encephalomyelitis virus subgroup strain-specific infection in a murine macrophage-like cell line

We compared infection of a murine macrophage-like cell line, J774-1, with two Theiler's murine encephalomyelitis virus subgroup strains. The GDVII strain, which is highly virulent and produces acute polioencephalomyelitis in mice, did not actively replicate in J774-1 cells, although there was a significant inhibition in cellular protein synthesis. In contrast, the DA strain, which is less virulent and causes demyelination with a persistent virus infection, productively infected J774-1 cells; however, there was less virus produced than in BHK-21 cells, and there was little if any cellular protein shutoff. These in vitro data may provide some explanation for the biological activities that are observed between both subgroup strains.

Modulation of endothelial cell nitric oxide synthase expression

The 5' promoter region of endothelial cell nitric oxide synthase (ecNOS) gene has several features which are compatible with a constitutively expressed, so called "housekeeping" gene. These include absence of a TATA box and the presence of Sp1 binding sites situated near the transcription start site. The promoter also contains sequences which suggest that it may be regulated by a variety of transcription factor-mediated signals. Studies of cultured endothelial cells show that ecNOS expression is modulated by shear stress, transforming growth factor beta, inhibition of protein kinase C, and the state of proliferation. These experiments indicate that although the ecNOS is a "constitutively expressed" gene, its content in the endothelium is subject to modest degrees of regulation which may have important physiological and pathophysiological implications.

Hemolytic characteristics of a pivot bearing supported Gyro centrifugal pump (C1E3) simulating various clinical applications

Centrifugal blood pumps are playing a key role in circulatory mechanical assist systems including cardiopulmonary bypass (CPB), right and left ventricular assist devices (RVAD and LVAD), percutaneous cardiopulmonary support (PCPS), and extracorporeal membrane oxygenation (ECMO). Each of these circulatory assist systems requires specific flow and pressure conditions. In vitro hemolysis tests were performed using five compact mock loops with flow and pressure set equivalent to clinical conditions. These studies determined the hemolytic characteristics and clinical applicability of the pivot bearing-supported Gyro centrifugal pump with an eccentric port (C1E3) compared with the Bio-Medicus pump (BP-80). Normalized index of hemolysis (NIH) values of the C1E3 were less than those of the BP-80 under all conditions; in particular, they were significantly less in the CPB, LVAD, and RVAD conditions. In addition, linear correlation was observed between NIH values, rotational pump speed (RPM), total pressure head (delta P), and flow rate (Q) with both the C1E3 and BP-80: NIH = a(RPM/Q) + b, NIH = c(delta P/Q) + d. However, the slopes (a and c) of these equations were smaller with the C1E3 than those with the BP-80, which suggests that the C1E3 has decreased hemolytic characteristics when increasing the RPM and delta P. In other words, the increase of RPM and delta P results in less shear stress with the C1E3 than with the BP-80. One cause of these decreased hemolytic characteristics of the C1E3 is thought to be less pump power loss against an increase of RPM and delta P than with the BP-80. Furthermore, the average exposure time is shorter with the C1E3 than with the BP-80 because the priming volume of the C1E3 (30 ml) is smaller than that of the BP-80 (80 ml). From the point of both shear stress and exposure time, the C1E3 has less hemolytic features than the BP-80.

A case of central pontine myelinolysis after surgical removal of a pituitary tumor

CASE REPORT

We have experienced a case in which surgical removal of a pituitary tumor from a male patient was followed by the occurrence of hyponatremia, which in turn was later associated with central pontine myelinolysis (CPM). A 4 X 3 X 3 cm pituitary tumor with hypothalamic extension was removed via a transsphenoidal approach. The post-operative course was uneventful until severe hyponatremia developed. To avoid drastic correction of electrolyte levels, reestablishment of normal serum levels was spread over 1 week. Following this, however, various neurologic symptoms such as pseudobulbar palsy, quadriplegia, extrapyramidal symptoms, and mental symptoms appeared. The case was diagnosed as CPM and extrapontine myelinolysis (EPM) on the basis of the clinical course and symptoms, and high-dosage steroid therapy was commenced.

RESULTS

There was consequent gradual improvement in symptoms. One month later, MRI revealed typical demyelination lesions in the central pons and striatum. Abnormal electrolyte conditions easily occur in pituitary tumors associated with hypothalamic extension in an altered hormone environment. It is known that CPM and EPM result from drastic correction of hyponatremia.

CONCLUSIONS

The frequent measurement of electrolytes and cautious correction of sodium imbalance are important for the prevention of CPM and EPM in the postoperative management of patients who undergo surgery for a pituitary tumor and whose high-dosage steroid therapy are effective.

Pump power loss and heat generation in a pivot bearing-supported Gyro centrifugal pump (C1E3)

Pump power loss is defined as input power that is not used for the output work of the pump. Less pump power loss means a higher pump efficiency. A common opinion is that the pump power loss is closely related to heat generation of the pump, which may affect not only the endurance of pump materials, but also blood damage in a blood pump. In this study, the relationship between pump power loss and heat generation in centrifugal blood pumps was investigated using the pivot-bearing supported Gyro C1E3 pump (C1E3) and Bio-Medicus pump (BP-80) under four different total pressure heat/flow conditions. A single special torque measuring driver motor was used for operating both the C1E3 and BP-80 in the four conditions. The pump power loss was calculated from the measured motor torque and hydraulic power. The changes in blood temperature were measured while the pump was operated at room temperature (25 degrees C) to obtain the following findings: First, the C1E3 caused less pump power loss and less temperature increase in blood than the BP-80 in all clinical simulated conditions that were tested; and second, the pump power loss and heat generation had a linear correlation with temperature rise from 22 to 25 degrees C in both the C1E3 and BP-80. During this period, approximately 30% of the pump power loss was transformed to heat, independent of the centrifugal blood pump type, provided that heat conduction through the pump housing and tubing was negligible during this particular period.

Development of a pivot bearing supported sealless centrifugal pump for ventricular assist

Since 1991, in our laboratory, a pivot bearing-supported, sealless, centrifugal pump has been developed as an implantable ventricular assist device (VAD). For this application, the configuration of the total pump system should be relatively small. The C1E3 pump developed for this purpose was anatomically compatible with the small-sized patient population. To evaluate antithrombogenicity, ex vivo 2-week screening studies were conducted instead of studies involving an intracorporeally implanted VADs using calves. Five paracorporeal LVAD studies were performed using calves for longer than 2 weeks. The activated clotting time (ACT) was maintained at approximately 250 s using heparin. All of the devices demonstrated trouble-free performances over 2 weeks. Among these 5 studies, 3 implantations were subjected to 1-month system validation studies. There were no device-induced thrombus formations inside the pump housing, and plasma-free hemoglobin levels in calves were within the normal range throughout the experiment (35, 34, and 31 days). There were no incidents of system malfunction. Subsequently, the mass production model was fabricated and yielded a normalized index of hemolysis of 0.0014, which was comparable to that of clinically available pumps. The wear life of the impeller bearings was estimated at longer than 8 years. In the next series of in vivo studies, an implantable model of the C1E3 pump will be fabricated for longer term implantation. The pump-actuator will be implanted inside the body; thus the design calls for substituting plastic for metallic parts.

A comparative study of acute and chronic diseases induced by two subgroups of Theiler's murine encephalomyelitis virus

Theiler's murine encephalomyelitis viruses (TMEV) are divided into two subgroups on the basis of their different biological activities. The GDVII strain produces acute polioencephalomyelitis in mice, whereas the DA strain produced demyelination with virus persistence in the spinal cord. A comparative study of GDVII and DA strains suggested that low host immune responses are responsible for the development of acute GDVII infection and that the persistence of infected macrophages plays a crucial role in the development of chronic white matter lesions in DA infection. All 78 mice infected with GDVII died or became moribund by day 13, while none of 54 mice infected with DA died. In the acute stage, the distribution of viral antigens in the central nervous system (CNS) tissue was similar in both GDVII and DA infections, although the virus titer was higher in GDVII infection. In DA infection, a substantial number of T cells were recruited to the CNS on day 6 when they were virtually absent in GDVII infection. The titer of neutralizing antibody was already high on day 6 in DA infection but was negligible in GDVII infection. Development of chronic paralytic disease from day 35 of the DA infection was accompanied by focal accumulation of viral antigen-positive macrophages in the spinal white matter. In addition, whiter matter lesions comparable to those in chronic DA infection were induced in the spinal cord within 7 days after intracerebral injection of DA-infected murine macrophages.

Regulation of expression of the endothelial cell nitric oxide synthase

1. Recent studies have provided insight into how the expression of endothelial cell nitric oxide synthase (ecNOS) is regulated. 2. The promoter of ecNOS has several features that are compatible with a constitutively expressed, so-called 'house keeping' gene. These include absence of a TATA box and the presence of Sp1 binding sites located near the transcription start site. The promoter also contains a number of putative binding domains which suggests that it may be regulated by a variety of transcription factor mediated signals. 3. Studies of cultured endothelial cells suggest that ecNOS expression is modulated by shear stress, transforming growth factor beta, inhibition of protein kinase C and the state of proliferation. These experiments indicate that although the ecNOS is a 'constitutively expressed' gene, its content in the endothelium is subject to modest degrees of regulation that may have important physiological and pathophysiological implications.

Epidemiological analysis of tularemia in Japan (yato-byo)

A total of 1372 cases of tularemia observed in Japan since 1924 were analysed. More than 90% of the cases were reported in the north-eastern part of the main island of Japan. After World War II, more than 40 cases were reported yearly for 20 years. Since 1966, however, there have been less than 10 cases per year. Ninety-three % of the cases were caused by contact with infected wild rabbits. The pattern of monthly distribution showed a peak in December and also a lower peak in May. The number of patients older than 40 years of age and the proportion of cases in females have gradually increased. In the earlier survey periods almost 70% of the cases were engaged in agriculture but at present this rate is less than 50%. The changes in the occurrence of tularemia in Japan is thought to be related to the change of life style caused by the rapid growth of the Japanese economy after World War II.

[Cardiac output in patients in their 90's]

Cardiac output was measured by the thermodilution method in nine patients aged 90 to 97 years. The patients were capable of walking in their daily lives before the injury or admission to the hospital, after which they were scheduled for operations. The causes for operations were localized and did not markedly influence general conditions of the patients. After heart rate, arterial blood pressure and mental condition of the patients had been stabilized, their cardiac outputs were determined before the induction of anesthesia. The results are as follows: Cardiac output: 3.58 +/- 0.90 l.min-1, cardiac index: 2.72 +/- 0.57 l.min-1.m-2. Previously published reports in Japan and the results of this study about the relationship between cardiac index and age suggest that as a whole there is a tendency for the cardiac index to decrease with aging.

Regulation of endothelial cell nitric oxide synthase mRNA expression by shear stress

Shear stress enhances expression of Ca(2+)-calmodulin-sensitive endothelial cell nitric oxide synthase (ecNOS) mRNA and protein in bovine aortic endothelial cells (BAEC). The present studies were performed to investigate mechanisms responsible for regulation of ecNOS mRNA expression by shear stress and to determine if this induction of ecNOS mRNA is accompanied by an enhanced nitric oxide (NO) production. Shear stresses of 15 dyn/cm2 for 3-24 h resulted in a two- to threefold increase of ecNOS mRNA content quantified by Northern analysis in BAEC. Shear stresses (1.2-15 dyn/cm2) for 3 h resulted in an induction of ecNOS mRNA in a dose-dependent manner. In human aortic endothelial cells, shear stresses of 15 dyn/cm2 for 3 h also resulted in ecNOS mRNA induction. In BAEC, this induction in ecNOS mRNA was prevented by coincubation with actinomycin D (10 micrograms/ml). The K+ channel antagonist tetraethylammonium chloride (3 mM) prevented increase in ecNOS mRNA in response to shear stress. The ecNOS promotor contains putative binding domains for AP-1 complexes, potentially responsive to activation of protein kinase C (PKC). However, selective PKC inhibitor calphostin C (100 nM) did not inhibit ecNOS induction by shear stress. Finally, production of nitrogen oxides under both basal conditions and in response to the calcium ionophore A-23187 (1 microM) by BAEC exposed to shear stress was increased approximately twofold compared with cells not exposed to shear stress. These data suggest that ecNOS mRNA expression is regulated by K+ channel opening, but not by activation of PKC, and that shear not only enhances ecNOS mRNA expression but increases capacity of endothelial cells to release NO.

Correlation of the polysaccharide antigens of Francisella tularensis with virulence in experimental mice

Francisella tularensis gives rise to two distinct colony types, acriflavine agglutination test-positive (acf+) and -negative (acf-) colonies. The acf+ variants were exclusively low virulent in mice, while the acf- variants were shown to be either high or low virulent. Three fractions, phosphate-buffered saline-extractable without heating, with heating at 60 C, and with heating at 100 C, were obtained from cultures of both the acf+ and acf- variants on agar media, and the polysaccharide antigens in those fractions were quantitated. All of the highly virulent acf- variants possessed a large amount of the polysaccharide antigen in the fraction extractable with heating at 60 C. This antigen was not, however, detected in any of the acf+ variants and one low-virulent acf- variant. It was also detected in a very low amount in some other acf- variants with low virulence. The amount of this polysaccharide antigen was therefore shown to be correlated with bacterial virulence in mice.

Dietary correction of hypercholesterolemia in the rabbit normalizes endothelial superoxide anion production

BACKGROUND

We have shown that hypercholesterolemia increases vascular superoxide anion (O2-) production, which could be responsible for augmented inactivation of endothelium-derived vascular relaxing factor. We sought to determine whether this increased vascular O2- production is due to infiltration of macrophages into the intima and whether dietary treatment of hypercholesterolemia normalizes O2- production.

METHODS AND RESULTS

A specific and sensitive assay for O2- based on chemiluminescence of lucigenin was used; the amount of O2- produced by vascular ring segments was quantified based on known quantities of O2- produced by xanthine-xanthine oxidase standards. O2- production of aortic segments from normal rabbits (n = 9), cholesterol-fed rabbits (1% cholesterol diet for 1 month, n = 7), and rabbits fed a 1% cholesterol diet for 1 month followed by a normal diet for 1 month (regression rabbits, n = 5) was measured. At the end of these diets, serum cholesterol levels were 1.5 +/- 0.2, 26.0 +/- 3.9, and 1.8 +/- 0.5 mmol/L (58 +/- 6, 1000 +/- 150, and 71 +/- 19 mg/dL) in the normal, cholesterol-fed, and regression animals, respectively. Vessels from normal rabbits with endothelium produced 0.32 +/- 0.06 nmol O2-/mg dry wt per minute, whereas those without endothelium produced approximately twice as much O2- (0.66 +/- 0.12 nmol O2- mg dry wt per minute. Vessels with endothelium from cholesterol-fed rabbits produced 4.5-fold more O2- than vessels from normal animals. This increased production of O2- was normalized by endothelial removal. This increased production of O2- was not due to infiltration of macrophages in the intima, because there was no correlation between vascular O2- production and macrophage infiltration assessed by immunohistochemistry with use of a specific antibody against rabbit macrophage. O2- production by vessels from regression rabbits was similar to that observed in normal animals, and as in the normal rabbits, endothelial removal increased O2- production. Aortic rings from these animals also were studied in organ chambers. Dietary lowering of cholesterol dramatically improved vasodilator responses to acetylcholine and A23187 (P < .05 versus cholesterol-fed rabbits).

CONCLUSIONS

Dietary lowering of cholesterol not only improves endothelium-dependent vascular relaxation but also normalizes endothelial O2- production. Decreases of O2- production by dietary lowering of cholesterol not only may improve vasomotor control but also may improve other aspects of vascular integrity in atherosclerosis.

Molecular regulation of the bovine endothelial cell nitric oxide synthase by transforming growth factor-beta 1

The promoter region of the endothelial cell nitric oxide synthase (ecNOS) gene contains potential response elements for transforming growth factor-beta 1 (TGF beta 1). TGF beta 1 plays an important role in the pathogenesis of atherosclerosis, vascular hypertrophy, and angiogenesis. We therefore sought to determine whether TGF beta 1 might modulate ecNOS expression in bovine aortic endothelial cells (BAEC). TGF beta 1 increased ecNOS mRNA in a dose-dependent manner. TGF beta 1 also increased ecNOS protein content. The production of nitrogen oxides (NOx), assessed by chemiluminescence, and nitric oxide synthase activity, assessed by arginine/citrulline conversion were increased in TGF beta 1-treated cells. Transcriptional activity of the 5'-flanking promoter region of the ecNOS gene was increased by TGF beta 1, as assessed by transfection with promoter/luciferase constructs. Deletion analysis suggested that the TGF beta 1-response element was present between nucleotides -1269 and -935 from the first transcription start site, in which a putative nuclear factor-1 (NF-1) binding site existed. Gel shift assays showed that nuclear protein(s), immunologically similar to CCAAT transcription factor/NF-1, bound to the putative NF-1 binding site in a sequence-specific manner. Mutation of the putative NF-1 binding site in the promoter/luciferase construct significantly decreased the responsiveness to TGF beta 1. In conclusion, TGF beta 1 increases ecNOS expression associated with an increase in production of NO in BAEC. This response is probably mediated by transcriptional activation of the ecNOS gene promoter.

Mechanisms of coronary hyperconstriction in response to serotonin induced by X-irradiation in miniature pigs: increased constrictive response of medial smooth muscle

Experimental and clinical studies suggest that X-irradiation to the coronary artery may enhance vasoconstrictive response. This study aimed to clarify the effect of X-irradiation on the vasomotor response of porcine coronary artery. X-ray (15 Gy) was selectively irradiated to the left anterior descending coronary artery (LAD) in 14 Göttingen miniature pigs. The coronary vasomotor responses to serotonin at the irradiated site (LAD) and the control site (the left circumflex artery; LCX) were assessed by quantitative arteriography before and 1 h and 1, 2, and 4 weeks after X-irradiation. At 2 weeks, endothelium-dependent vasodilation in response to substance P was also evaluated arteriographically in vivo. At 2 weeks, isometric tension studies were performed to evaluate the constrictive responses of medial muscle strips and endothelium-dependent relaxation. Coronary vasoconstriction in response to serotonin was enhanced 1 week after, and further augmentation was noted 2 and 4 weeks after X-irradiation. Endothelium-dependent vasodilation in response to substance P in vivo was preserved 2 weeks after X-irradiation. Coronary arteriography showed no organic stenosis at the irradiated site. In vitro studies demonstrated that medial muscle strips of the irradiated site showed hypercontraction in response to serotonin and that endothelium-dependent relaxation in response to serotonin and substance P was preserved at the irradiated site. A histological study revealed no appreciable changes of the endothelial cells or intimal thickening.(ABSTRACT TRUNCATED AT 250 WORDS)

Initial clinical experience with the Baylor-Nikkiso centrifugal pump

Recently, a newly developed centrifugal pump, the Baylor-Nikkiso pump, was approved for clinical use in the United States. This pump is the most compact centrifugal pump with a priming volume of only 25 ml. Although it is small, this pump can provide a flow of 4 L/min against a total pressure head of 300 mm Hg at 3,000 rpm. In vitro and in vivo validation of the Baylor-Nikkiso pump has proved that this pump could effectively reduce blood trauma even under high total head pressure. In addition, 48-h durability tests with biventricular bypass using calves verified the reliability of shaft sealing and antithrombogenicity. Clinical trials of the Baylor-Nikkiso pumps have been initiated in our department. This pump provides flows of 60-70 ml/kg/min with stable hemodynamic conditions. No leakage of thrombus formation was observed. The results of the initial clinical experience of the Baylor-Nikkiso pump suggest that it is suitable for cardiopulmonary bypass surgery.

In vitro analysis of the floating mode phenomenon in the Free Impeller Gyro Pump

The Free Impeller Gyro Pump was designed based on a new concept of free impeller, in which the rotational shaft and the mechanical bearings were completely eliminated from the impeller. Due to this characteristic design, a phenomenon occurred in which the impeller lifted off the bottom of the pump housing in a certain range of pumping conditions during the initial in vitro studies (floating mode). We studied this floating mode in detail using a Hall effect position sensor to monitor the impeller position. A Hall sensor signal recorded on the strip chart, which represents the distance between the impeller top and the pump ceiling, proved the existence of the floating mode. By analyzing the data in detail, it was also verified that the floating mode was composed of three subdivided phases: latent, transitional, and dominant. Furthermore, stability of the impeller rotation in the floating mode against the change of pump orientation was also exhibited in this study. These results suggests that the Free Impeller Gyro Pump should possess high antithrombogenicity, atraumatic features, no bearing wear, and stable performance when operated within the range of the floating mode.

[Evaluation of preoperative blood preparation and blood consumption for implementation of type and screen and maximum surgical blood order schedule]

We analyzed preoperative blood preparation and intraoperative blood transfusion in Kagawa Prefectural Central Hospital and evaluated the effectiveness of maximum surgical blood order schedule (MSBOS) and Type and Screen (T&S). Forty seven kinds of surgery were performed on 1,283 cases from May, 1991 to April, 1992. Transfusion was performed in 179 cases of them. All of 1,884 units of blood that had been prepared, were crossmatched and 1,078 of them were actually transfused. The Crossmatched to Transfused ratio (C/T ratio) was 1.71. If we adopted MSBOS and T&S in 13 elective surgery, 766 units of blood and labour work for preoperative blood preparation could have been saved. MSBOS and T&S are beneficial for efficient usage of blood transfusion in surgery.

Vasoreactivity and restenosis after coronary angioplasty in the atherosclerotic pig model

BACKGROUND

The effect of coronary angioplasty on coronary spasm remains unknown. We examined the effects of balloon angioplasty, using an oversized balloon, on coronary hypercontraction and eventual restenosis in a pig model of coronary spasm.

METHODS

We performed balloon angioplasty, using an oversized balloon at the site of coronary spasm superimposed on atherosclerosis with 6 (group A, n = 14) or 1 (group B, n = 14) atmospheres of inflation pressure in miniature pigs. Using coronary angiography we assessed the coronary basal diameter and diameter change in response to histamine and serotonin before, immediately after, and 4 weeks after angioplasty. Histological examinations were performed immediately after and 4 weeks after the angioplasty.

RESULTS

Before angioplasty, histamine- and serotonin-induced hypercontraction was reproducibly noted at the atherosclerotic site. Immediately after angioplasty, the coronary diameter became larger (P < 0.01) than before angioplasty in group A, but there was no significant difference in group B. The hypercontraction in group A was abolished immediately after and 4 weeks after angioplasty, whereas the hypercontraction in group B was unchanged. Histological examination revealed medial necrosis immediately after and medial fibrosis 4 weeks after angioplasty, which were more prominent in group A. Four weeks after angioplasty, the magnitude of restenosis was greater in group A than in group B.

CONCLUSIONS

Angioplasty using an oversized balloon with the higher atmosphere of inflation pressure abolished coronary hypercontraction immediately after and 4 weeks after angioplasty, which probably resulted from the irreversible damage to medial smooth muscles; however, this did not prevent restenosis.

Regulation of endothelial constitutive nitric oxide synthase by protein kinase C

Protein kinase C (PKC) plays a key role in a variety of signal transduction processes. The promoter region of the endothelial constitutive nitric oxide synthase (ecNOS) gene contains a transcriptional factor AP-1 binding element. In the present study, we sought to determine the effect of PKC inhibition on the expression of ecNOS in cultured bovine aortic endothelial cells (BAEC). The PKC inhibitor staurosporine (10 to 100 nmol/L) increased the expression of ecNOS mRNA, assessed by Northern analysis, in a dose-dependent manner. A newly developed, more specific PKC inhibitor, chelerythrine (1 to 3 mumol/L), also increased the level of ecNOS mRNA. Incubation of BAEC with phorbol 12-myristate 13-acetate (100 nmol/L) for 24 hours, which downregulates PKC, increased ecNOS mRNA expression. The protein content of ecNOS, assessed by Western analysis, was also increased in staurosporine-treated or chelerythrine-treated BAEC. The release of nitrogen oxides from staurosporine-treated or chelerythrine-treated cells both under basal conditions and in response to calcium ionophore A23187 was significantly increased (P < .05). In conclusion, the present study suggests that regulation of ecNOS is mediated by PKC. The increased release of nitric oxide induced by PKC inhibition may play a protective role against atherogenic process.

Clinical evaluation of the oscillometric blood pressure monitor in adults and children based on the 1992 AAMI SP-10 standards

OBJECTIVE AND METHODS

A noninvasive blood pressure monitor (model BP8800MS, Colin Medical Instruments Corp., San Antonio, TX) that uses the oscillometric principle was evaluated against the manual auscultatory method in 85 adults and 85 children following the requirements of the 1992 AAMI SP-10 standard. This was the first evaluation study of the electronic sphygmomanometers according to the new AAMI standards.

RESULTS

In adult subjects, the mean difference and standard deviation of the differences between the oscillometric and auscultatory methods were 2.81 +/- 5.35 mm Hg (mean +/- SD) for systolic and 0.04 +/- 4.90 mm Hg for diastolic; in children, they were 3.18 +/- 5.96 mm Hg for systolic and -0.82 +/- 5.24 mm Hg for diastolic. Excellent correlation between the oscillometric and auscultatory methods, particularly the diastolic pressure, is due to usage of the Phase V Korotkoff's sounds for auscultatory detection of the diastolic pressure, increased accuracy of the two observers' measurements, and proper selection of cuff sizes depending on the mid-arm circumference. Five different-sized cuffs were used in this study. The cuff-width-to-midarm circumference ratio was adjusted to be 0.4 or larger to minimize the measurement error associated with mismatch of cuff-size/arm-size relationship. The distribution of errors associated with each cuff was nearly the same.

CONCLUSIONS

The 1992 AAMI SP-10 standards offer a thorough evaluation of the oscillometric sphygmomanometer by enforcing more stringent criteria on (1) agreement between two observers, (2) wide spectrum of blood pressure from hypertensive (above 180 mm Hg) to hypotensive, and (3) data analysis. The oscillometric blood pressure monitor evaluated in this study meets the specifications of the new AAMI SP-10 standards and can offer an accurate, automatic, and noninvasive measure of both systolic and diastolic blood pressure in adults and children. It can safely replace the manual or automatic auscultatory system in various clinical settings.

Physiologic consequences of increased vascular oxidant stresses in hypercholesterolemia and atherosclerosis: implications for impaired vasomotion

During the past 8 years, it has become apparent that endothelium-dependent vascular relaxation is abnormal in a variety of disease states, including hypercholesterolemia, atherosclerosis, diabetes, hypertension, and following heart transplantation. Our laboratory and several others have examined dysfunctional regulation of vasomotor tone in hypercholesterolemia and atherosclerosis. These studies have led to the concepts that altered regulation of vasomotion by the endothelium (1) is an early development in atherosclerosis, (2) involves both large vessels (with overt atherosclerosis) and the microcirculation (in which atherosclerosis does not develop), and (3) can be reversed by lipid-lowering strategies. The mechanisms for the abnormalities underlying this form of endothelial dysfunction are likely multifactorial, but a major underlying factor appears to be increased oxidant degradation of endothelium-derived nitric oxide. In this review we examine the evidence supporting this conclusion and consider the implications of these findings.

Inhibitory effects of aspirin on coronary hyperreactivity to autacoids after arterial balloon injury in miniature pigs

We examined the effects of aspirin on coronary hyperreactivity to autacoids after arterial balloon injury in miniature pigs. Coronary vasoconstriction induced by histamine and serotonin were examined angiographically before, 1 h, 1 week, and 1 month after balloon injury in 29 hypercholesterolemic miniature pigs. The animals were divided into three groups: group A, no treatment (n = 16); group B, pretreated with aspirin 50 mg/day for 2 days before injury (n = 7); and group C, treated with aspirin 50 mg/day for 2 days before and 5 days after injury (7 days in all) (n = 6). In group A, coronary vasoconstriction induced by autacoids was significantly greater at the injured than at the noninjured site at all times examined (p < 0.01). Hyperconstriction induced by the autacoids 1 h after injury were significantly less in groups B and C than in group A (p < 0.01). Hyperconstriction induced by autacoids 1 week after injury were significantly less in group B than in group A (p < 0.01) and were significantly less in group C than in group A (p < 0.01) or group B (p < 0.05). Treatment with aspirin for 2 or 7 days had no effect on the constrictive responses at the injured site 1 month after injury or on those at the noninjured site at all times examined. These results suggest that platelet-vessel wall interaction may play an important role in coronary hyperconstrictive responses to autacoids 1 h and 1 week after injury.

The endothelial cell nitric oxide synthase: is it really constitutively expressed?

During the past two years, the enzyme responsible for production of endothelium-derived nitric oxide, the endothelial cell NO synthase (ecNOS) has been cloned and the gene encoding this enzyme isolated, cloned and its structure characterized. This research has provided direction for a variety of studies of regulation of the ecNOS. Several features of the ecNOS are compatible with a constitutively expressed, poorly regulated gene, including absence of a TATA box and numerous SP-1 sites. The promoter also contains a number of putative binding domains which suggest that it may be regulated by a variety of transcription factor mediated signals. In this review we will discuss evidence to support the concept that the ecNOS is a constitutively expressed gene subject to a modest degree of regulation by important physiological influences.

[The pathomechanisms of virus-induced demyelination]

The pathomechanisms of virus-induced demyelination have been widely studied, especially in animal models, in order to elucidate the pathogenesis of a human demyelinating disease, multiple sclerosis. The recent development of molecular biology has partially defined the genomic segment responsible for demyelination in some viruses. It is, however, still unclear, how such a segment causes demyelination. Three main issues have been addressed regarding the mechanisms of demyelination, i.e., oligodendrocyte lytic viral infection, immune-mediated demyelination with oligodendrocyte viral infection, and immune-mediated demyelination without oligodendrocyte viral infection. Immune responses of the host are, therefore, critical, as well as viral replication and propagation in virus-induced demyelination.

Development and evaluation of antithrombogenic centrifugal pump: the Baylor C-Gyro Pump Eccentric Inlet Port Model

The Baylor C-Gyro Pump Eccentric Inlet Port Models (C1E) have been developed aiming for a long-term centrifugal ventricular assist device (VAD) as well as a cardiopulmonary bypass pump. The eccentric inlet port models are characterized by their unique inlet port and secondary impeller vanes. An inlet female pivot bearing, which was fixed to a supporting bar in the prototype model, is directly embedded into the ceiling of the pump casing. An inlet port is then placed off-center to avoid the bearing area, and it is angled between 0 to 90 degrees from the upright position. In addition, small secondary vanes were incorporated into the impeller bottom to accelerate the washout flow behind the impeller. These features attained design objectives proposed for higher antithrombogenicity: a seal-less pump chamber, no stationary parts in the blood path, and acceleration of the secondary flow behind the impeller. The first in vivo experiment using C1E pumps showed excellent antithrombogenicity for up to 18 days when the experiment ceased due to severe infection in the calf.

Does hematocrit affect in vitro hemolysis test results? Preliminary study with Baylor/NASA prototype axial flow pump

The effect of hematocrit (Ht) on in vitro hemolysis test results (i.e., index of hemolysis) was evaluated using a Baylor/NASA prototype axial flow pump. Red blood cell suspensions of six different Ht (5, 10, 15, 20, 30, 40%; n = 30) were prepared and used for this evaluation. The pump was operated for 60 min under 5 L/min flow conditions, and blood samples were taken every 10 min to measure plasma free hemoglobin levels. The normalized index of hemolysis (NIH) was calculated using the regression line slope between time and plasma free hemoglobin level, and relationships between NIH and Ht or hemoglobin (Hb) were checked. NIH and Ht had a statistically significant (p < 0.0001) correlation with a coefficient of fit of 0.976, and NIH and Hb had a statistically significant (p < 0.0001) correlation with a coefficient of fit of 0.976. To reduce the effect of Ht, NIH/Ht was proposed and compared with a modified index of hemolysis (MIH), which was normalized by the Hb level of blood. NIH/Ht and MIH had a poor correlation with Ht (coefficient of fit, 0.608) and Hb (coefficient of fit, 0.577), respectively. When blood that has a wide range of Ht or Hb values is used for in vitro hemolysis tests, NIH/Ht is suggested for use as an index of hemolysis to evaluate the hemolysis characteristics of rotary blood pumps because MIH has no dimension and it requires Hb values. In contrast, NIH/Ht has a dimension of g/100 L, which is quite understandable, and it does not require measurement of Hb levels of blood; it is therefore cost-effective.

The Baylor total artificial heart. Flow visualization studies

To analyze the flow patterns of the left blood chamber of the Baylor total artificial heart (TAH) and to evaluate influences of the inflow valve angle to the flow patterns, flow visualization studies were performed. The inflow valve angle of the left housing was changed by 20 degrees orthogonal to the inflow tube, and comparison studies of the modified and unmodified models were made. For evaluating sectional flow patterns, a laser light was used, the clear transparent housing was scanned segmentally, and flow patterns were recorded on high contrast film for measuring flow velocities. A signal was used that synchronized the timing of the camera shutter to the pusher-plate movement signal. With the modified 20 degree inflow valve direction, there were better closing characteristics of the inflow valve leaflets. At the same time, we could successfully reduce the vortex formation at the inflow port, which may cause thrombus formation. We also have improved the washout during the diastolic phase in not only the bottom area, but in the entire pumping chamber. This flow visualization setup is simple and inexpensive. It is useful not only for validation of global flow patterns, but also for validation of local flow velocities of various blood pumps.

Lysophosphatidylcholine increases vascular superoxide anion production via protein kinase C activation

We tested the hypothesis that lysophosphatidylcholine (lyso-PC) could activate protein kinase C in intact vascular segments and sought to examine some of the physiological consequences of this activation. In segments of rabbit aorta, the patterns of protein phosphorylation determined by two-dimensional electrophoresis stimulated by lyso-PC and 12-O-tetradecanoylphorbol 13-acetate (TPA) were similar. Activation of protein kinase C can stimulate superoxide anion (O2-) production in other tissues, and we found that lyso-PC-treated rabbit aortas produced twofold more O2- than control vessels. Calphostin C, a potent and specific inhibitor of protein kinase C, attenuated O2- production in lyso-PC-treated vessels but had no effect in control vessels. The effect of lyso-PC on O2- production was mimicked by TPA. In separate bioassay studies, release of the endothelium-derived vascular relaxing factor (EDRF) quantified by the response of detector vessels was markedly impaired after exposure of donor rabbit aortic segments to lyso-PC. After incubation with calphostin C, EDRF release in response to acetylcholine from lyso-PC-treated donor vessels was restored significantly. Thus, lyso-PC can activate protein kinase C in intact vessels, leading to an increase in O2- production. Activation of protein kinase C by lyso-PC may also play a role in altering the release of EDRF in response to acetylcholine. Increased O2- production in response to lyso-PC may have important consequences in the atherogenic process.