Phase control of a z-current-driven plasma column

A dynamic mitigation is presented for sausage and kink instability growths of a z-current-driven magnetized plasma column. In this Rapid Communication we found that a wobbling motion of the z-current electron axis induces a phase-controlled perturbation, so that the growths of the sausage and kink instabilities are successfully and remarkably mitigated. In general, plasma instabilities emerge from perturbations, and the perturbation phase is normally unknown. However, if the perturbation phase is known or actively imposed by, for example, a designed driver wobbling behavior, the instability growth would be controlled and mitigated by a superimposition of the perturbations imposed. The results in this Rapid Communication demonstrate that the wobbling z-current electron beam would provide an improvement in the plasma column stability and uniformity.

96Zr beam production for isobar experiment in relativistic heavy ion collider

To investigate the chiral magnetic effect, ⁹⁶Zr and ⁹⁶Ru beams were accelerated at the relativistic heavy ion collider (RHIC) during Run-18 at Brookhaven National Laboratory. The ⁹⁶Zr beam was provided from the electron beam ion source (EBIS) injector, which consists of a laser ion source, an EBIS high charge state ion breeder, a 300 keV/u radio frequency quadrupole, and a 2 MeV/u interdigital H type drift tube linear accelerator (IH-DTL). The natural abundance of ⁹⁶Zr is only 2.8% with about 50% of ⁹⁰Zr. To obtain a sufficient beam current, Zr material enriched to about 60% of ⁹⁶Zr was used. The only available form of the enriched material was zirconium oxide (ZrO₂) powder, which was not well suited for a laser ion source target. We studied and established a sintering technique of the ZrO₂ powder to make a solid sample which could be installed into the laser ion source. The singly charged Zr was produced in a laser ablation plasma, extracted, and delivered to the EBIS to be ionized further to ⁹⁶Zr¹⁶⁺. We optimized the laser irradiation condition, the EBIS confinement time, and transport through the RF linacs to maximize the performance of the injector. The total number of shots provided from the laser ion source for injection into the EBIS was 489 910. The EBIS facility provided a 192 MeV stable beam of ⁹⁶Zr¹⁶⁺ ions to the booster ring of alternating gradient synchrotron (AGS) for further acceleration and stripping in the AGS/RHIC complex, allowing for successful data acquisition at the Solenoidal Tracker at the RHIC.

Effect of a saline flush technique for head and neck imaging in dual-energy CT: improvement of image quality and perivenous artefact reduction using virtual monochromatic imaging

AIM

To evaluate the effect of the saline flush (SF) technique on the depiction of lesions and the reduction of perivenous artefacts in the head and neck region using dual-energy computed tomography (CT) with virtual monochromatic imaging (VMI).

MATERIALS AND METHODS

Fifty patients with head and neck cancer were divided into two groups: group A, without a SF and group B, with a 30-ml SF. All images were acquired using fast kilovolt-switching CT (Revolution HD, GE Healthcare, Milwaukee, WI, USA). Contrast-to-noise ratios (CNRs) of the lesions were calculated at VMI energy levels ranging from 40 to 80 keV. Subjective analysis of overall image quality, delineation of lesions, and perivenous artefacts was conducted by two reviewers at both VMI energy level 40 keV and the optimal energy level (which showed optimal CNR by objective analysis).

RESULTS

Optimal energy level was 63 keV for group A and 61 keV for group B. At VMI energy levels ranging from 40 to 80 keV, the CNR was higher for group B. The highest subjective overall image quality was shown for group B at the optimal energy level (subjective image quality mean value, 3.40). Subjective delineation of lesions was comparable. The perivenous artefact score was significantly higher for group B (2.44 versus 2.74 [p<0.05] at 40 keV, 3.20 versus 3.46 [p<0.05] at the optimal energy level).

CONCLUSION

The SF technique results in an improvement of lesion CNR and a reduction of perivenous artefacts in VMI using duel-energy CT, especially at 40 keV.

Mikroskopische Struktur der gestörten Strömung im arteriellen und venösen

Der Verfasser hat die Strömungsmuster in verschiedenen Regionen gestörter Strömung im kardio- und zerebrovaskulären System bei Hund und Mensch mit Hilfe isolierter transparenter natürlicher Arterien und Venen untersucht und in Einzelheiten die dreidimensionale Struktur der gestörten Strömung beobachtet. Die dabei dokumentierten Details der Strömung kann man in Verbindung mit der Lokalisation von Gefäßerkrankungen im Kreislaufsystem setzen. Früher waren solche Informationen nicht verfügbar, da weder Techniken wie Angiographie oder Ultraschall-Doppler-Technik noch die modernsten und kompliziertesten diagnostischen Techniken wie Computertomographie, Positronen-Emissionscomputertomographie und Kernresonanzmessung derartige

Veränderungen erfassen. Die Ergebnisse sind von großer Bedeutung und essentiell für unser Verständnis der Rolle fluiddynamischer Faktoren in der Lokalisation von Gefäßerkrankungen, von Thrombose, von Atherosklerose sowie von Aneurysmen in der Zirkulation. Diese Kenntnisse, die durch die vorliegenden Untersuchungen erworben wurden, werden uns in der Zukunft nicht nur helfen, die fluiddynamischen Einzelheiten der Zirkulation beim Säuger im Zusammenhang mit der Lokalisation der Gefäßkrankheiten zu sehen, sondern auch die Ergebnisse der wichtigsten angiographischen Tests zu verstehen. Darüber hinaus werden die Ergebnisse Richtlinien für die optimale Gestaltung von Strömungskanälen in künstlichen inneren Organen geben, ebenso für die Anordnung und Gestaltung von Gefäßprothesen. Beide künstliche Organsysteme sind gemeinsam mit der Problematik rascher Thrombusbildung behaftet, was auch für Gefäß- Bypass-Operationen (etwa im Koronarsystem), ebenso für andere Gefäßrekonstruktionsmaßnahmen gilt. Auch diese setzen den Patienten aufgrund abnormer Strömungsbedingungen in einigen Fällen dem Risiko postoperativer Thrombose aus.

Flow patterns and preferred sites of intimal thickening in bypass-grafted arteries

AIM

In bypass-grafted arteries, anastomotic intimal hyperplasia develops more markedly at the distal junction than the proximal one. It is likely that it arises from the difference in flow patterns at these two sites. Therefore we have studied the relationship between the flow patterns and precise locations of wall thickening specific to the particular vessel.

METHODS

In total 30 bypass-grafting procedures were carried out on the femoral arteries of dogs with 10 autologous common carotid arteries and 20 saphenous veins. The vessels were harvested at 3 months after operation, and precise locations of intimal thickening and characteristics of the flow such as flow patterns and distributions of fluid velocity and wall shear stress were studied in detail.

RESULTS

At the proximal anastomosis, a large recirculation zone was formed only at the inlet of the partially or totally occluded host artery, whereas at the distal anastomosis, it was formed at both the floor of the host artery and the toe of the bypass in most vessels, and the former was connected to the latter, extending the region of disturbed flow to lateral walls of the host artery. Wall thickening was found mainly in these regions occupied with slow secondary and recirculation flows where wall shear stress was very low.

CONCLUSION

The flow at the distal anastomosis is more disturbed and complex than that at the proximal anastomosis. This difference in flow pattern that determine the region of low wall shear stress might explain why intimal hyperplasia develop more markedly at the distal junction.

Effect of flow disturbances remaining at the beginning of diastole on intraventricular diastolic flow and colour M-mode Doppler echocardiograms

A computational model of the fluid dynamics of intraventricular flow was used to investigate the importance of the effects of flow disturbances existing within the left ventricle (LV) at the onset of diastole on a diastolic flow field. The simulation started with a quiescent flow state; it continued for a number of cardiac cycles to obtain a cyclically repeatable flow. After the flow became periodic, the initial diastolic flow was not quiescent: flow disturbances, remnants of a systolic flow, were present within the LV. Nevertheless, they faded away during an acceleration phase of diastole and almost ceased by the end of this phase. Consequently, a flow field during a deceleration phase of diastole, characterised by the formation of a vortex ring, was hardly affected by the initial flow disturbances. The propagation velocity of a colour M-mode Doppler echocardiogram obtained by scanning velocity along the LV long axis was 0.58 m s(-1) in the case where diastolic flow was initially quiescent and 0.56 m s(-1) in the case where flow disturbances existed at the beginning of diastole. These results indicated that the colour M-mode Doppler echocardiographic technique captures flow dynamics produced purely by ventricular expansion, with little influence from initial diastolic flow disturbances.

Computational study on the evolution of an intraventricular vortical flow during early diastole for the interpretation of color M-mode Doppler echocardiograms

A computational fluid dynamics study of intraventricular flow during early diastole was carried out using a 3D model of the human left ventricle (LV). It was found that a vortical flow formed under the aortic orifice and then grew in size and extended laterally along the ventricular wall towards the posterior side. With further expansion of the LV, it developed into an annular vortex asymmetrically enlarged on the side of the aortic orifice, narrowing the passage of blood inflow and thus causing a shift of the high-velocity portion of inflow towards the apex. This appeared as an elongation of the aliasing area when the velocity of the inflow was expressed as a spatiotemporal map in the same manner as a color M-mode Doppler (CMD) echocardiogram. Based on these findings, it was concluded that the shape of the aliasing area in a CMD echocardiogram shows the change in the velocity of blood inflow affected by the development of an annular vortex formed in the LV.

Theoretical study of the effect of local flow disturbances on the concentration of low-density lipoproteins at the luminal surface of end-to-end anastomosed vessels

To elucidate the mechanisms of localisation of intimal hyperplasia in anastomosed arteries, the effects of flow disturbances on the transport of low-density lipoproteins (LDLs) from the flowing blood to the wall of end-to-end anastomosed arteries, with and without a moderate stenosis, were studied theoretically by means of a computer simulation under the condition of steady flow. In an artery with moderate stenosis at the anastomotic junction and intimal thickening distal to it, we found that, owing to the water-permeable nature of the arterial wall, the surface concentration of LDL was elevated up to 20% higher than that of the bulk flow distal to the stenosis, where a recirculation zone was formed and wall shear stresses were low. In contrast to this, no significant elevation of surface concentration of LDLs occurred in another anastomosed vessel in which no stenosis was formed and no intimal thickening was observed. These results suggest that flow-dependent concentration polarisation of LDLs plays a causative role in the localisation of anastomotic intimal hyperplasia in the human arterial system by locally elevating the surface concentration of LDLs, thus augmenting their uptake by endothelial cells.

p38 MAPK and Ca2+ contribute to hydrogen peroxide-induced increase of permeability in vascular endothelial cells but ERK does not

To examine the involvement of p38 mitogen-activated protein kinase (p38 MAPK) and extracellular signal-regulated kinase (ERK) in the oxidative stress-induced increase of permeability in endothelial cells, the effects of a p38 MAPK inhibitor (SB203580) and ERK inhibitor (PD90859) on the H2O2-induced increase of permeability in bovine pulmonary artery endothelial cells (BPAEC) were investigated using a two-compartment system partitioned by a semi-permeable filter. H2O2 at 1 mM caused an increase of the permeation rate of fluorescein isothiocyanate (FITC)-labeled dextran 40 through BPAEC monolayers. SB203580 inhibited the H2O2-induced increase of permeability but PD98059 did not, though activation (phosphorylation) of both p38 MAPK and ERK was observed in H2O2-treated cells in Western blot analysis. An H2O2-induced increase of the intracellular Ca2+ concentration ([Ca2+]i) was also observed and an intracellular Ca2+ chelator (BAPTA-AM) significantly inhibited the H2O2-induced increase of permeability. However, it showed no inhibitory effects on the H2O2-induced phosphorylation of p38 MAPK and ERK. The H2O2-induced increase of [Ca2+]i was not influenced by SB203580 and PD98059. These results indicate that the activation of p38 MAPK and the increase of [Ca2+]i are essential for the H2O2-induced increase of endothelial permeability and that ERK is not.

[A pertussis outbreak in a ward for severely retarded]

In June 2000, many cases with persistent cough were observed among inpatients and the staff of a ward for severely retarded. Some of them had symptoms suggestive of pertussis, such as whooping, post-tussive apnea. We performed a retrospective investigation to assess symptoms and serological findings suspicious of pertussis. There were a total of 14 cases of persistent cough over 3 weeks (4 to 9 weeks). 6 cases were inpatients and 8 were hospital staff. Of those, serological test for pertussis infection was performed in 10 cases and 6 cases were diagnosed as serologically confirmed pertussis. The other cases with persistent cough were also considered to be probable pertussis as they have had intensive contact with serologically confirmed cases. 12 cases were treated by antibiotics, but they all failed to respond. It was suggested that Bordetella pertussis must be considered as a causal organism of persistent cough even in adults. To prevent nosocomial transmission of pertussis, droplet precautions and macrolide treatment should be provided for patients with symptoms highly suggestive of pertussis.

Visualization of flow-dependent concentration polarization of macromolecules at the surface of a cultured endothelial cell monolayer by means of fluorescence microscopy

To substantiate the occurrence of flow-dependent concentration or depletion of atherogenic lipoproteins, which has been theoretically predicted to take place at a blood/endothelium boundary, we have studied the effects of perfusion pressure and wall shear rate on the accumulation and uptake of microspheres by cultured vascular endothelial cells in a monolayer. The study was carried out by flowing a cell culture medium containing fetal calf serum and fluorescent microspheres through a parallel-plate flow chamber having a cultured bovine aortic endothelial cell (BAEC) monolayer on one wall of the chamber. The microspheres had a nominal diameter of 19 nm, approximately the same as that of low-density lipoproteins, and thus served as models and tracers of plasma proteins and lipoproteins. Experiments were carried out in steady flow in the physiological range of wall shear rate and water filtration velocity at the monolayer, while monitoring the intensity of fluorescence of the spheres accumulated at and taken up by the endothelial cells. It was found that in a perfusate containing only fluorescent microspheres, due to increased phagocytic activity of the endothelial cells, the intensity of fluorescence which reflected the number of the microspheres taken up by the endothelial cells, increased almost linearly with time and independently of wall shear rate. However, with perfusates containing fetal calf serum, this abnormal phenomenon did not occur, and the intensity of fluorescence increased with increasing perfusion pressure and decreasing wall shear rate. It was also found that the number of fluorescent microspheres accumulated at and taken up by the BAEC monolayer was shear-dependent only at low wall shear rates, and increased sharply when the flow rate was reduced to zero. These results provided solid experimental evidence that flow-dependent concentration or depletion of macromolecules occurs at the luminal surface of the endothelium at physiological wall shear rates and water filtration velocities, and strongly supports the hypothesis that flow-dependent concentration polarization of lipoproteins plays an important role in the localization of atherosclerosis and intimal hyperplasia in man by facilitating the uptake of atherogenic lipoproteins by endothelial cells.

Tranexamic acid: a "diuretic" for the peritoneal membrane?

The aim of the study was to use an animal model to investigate the mechanisms by which tranexamic acid (TNA) increases ultrafiltration (UF) volume. Thirty Sprague-Dawley rats were studied in three groups (n = 10, each group). Group 1 was dialyzed with conventional dialysis solution, group 2 with conventional fluid plus low-dose TNA (300 mg/L), and group 3 with conventional fluid plus high-dose TNA (3000 mg/L). A PD catheter was inserted into each animal, and 25 mL of the designated dialysis fluid was injected twice daily for two weeks, starting seven days after surgery. Peritoneal transport properties (PTP) were measured by modified peritoneal equilibration test (PET), and transcapillary ultrafiltration (TCUF) and lymphatic absorption (LA) were determined by using dextran 70 weekly. Histological examinations of the peritoneum were performed at the end of the experiment. Drained dialysate volume (DDV) decreased in all groups; however, a lower reduction in DDV was seen in the TNA groups. PTP increased and TCUF decreased in all groups. LA increased in Group 1, but was unchanged in the other groups. No significant histological changes of the peritoneum were observed in any group. This study confirmed that, in rats, TNA maintained UF volume by reducing LA without serious adverse effects. We may safely use TNA as a "diuretic" for the peritoneal membrane.

Flow-dependent concentration polarization of plasma proteins at the luminal surface of a cultured endothelial cell monolayer

Flow-dependent concentration or depletion of atherogenic low density lipoproteins which has been theoretically predicted to occur at a blood/endothelium boundary may play an important role in the genesis, progression, and regression of atherosclerosis in man and intimal hyperplasia in vascular grafts implanted in the arterial system in man and experimental animals. Hence to explore such a possibility, we have studied the effect of a steady shear flow on concentration polarization of plasma proteins and lipoproteins at the luminal surface of a cultured bovine aortic endothelial cell (BAEC) monolayer which served as a model of the vessel wall of an artery or an implanted vascular graft. The study was carried out by circulating a cell culture medium containing fetal calf serum or bovine plasma lipoproteins in steady flow through a parallel-plate flow cell in which a cultured BAEC monolayer was installed, over the physiologic ranges of wall shear rate and water filtration velocity at the BAEC monolayer. The water (cell culture medium) filtration velocity at the BAEC monolayer was determined to provide a measure of the change in concentration of plasma protein particles at the luminal surface of the BAEC monolayer. It was found that for perfusates containing plasma proteins and/or lipoproteins, water filtration velocity varied as a function of flow rate, being lowest in the absence of flow. Water filtration velocity increased or decreased as flow rate increased or decreased from an arbitrarily set non-zero value, indicating that surface concentration of protein particles varied as a direct function of flow rate, and the process was reversible. It was also found that at particle concentrations equivalent to those found in a culture medium containing serum at 20% by volume, plasma lipoproteins which were much smaller in number and lower in concentration but larger in size than albumin, showed almost the same effect as observed with serum which contained both lipoproteins and albumin, indicating that the substance responsible for this phenomenon is not albumin but lipoprotein whose diffusivity is much smaller than that of albumin. The results strongly support our hypothesis that flow-dependent concentration polarization of lipoproteins occurs at a blood endothelium boundary, and this in turn promote the localization of various vascular diseases which develop in our arterial system.

Theoretical study on flow-dependent concentration polarization of low density lipoproteins at the luminal surface of a straight artery

It is suspected that physical and fluid mechanical factors play important roles in the localization of atherosclerotic lesions and intimal hyperplasia in man by affecting the transport of cholesterol in flowing blood to arterial walls. Hence, we have studied theoretically the effects of various physical and fluid mechanical factors such as wall shear rate, diffusivity of low density lipoproteins (LDL), and filtration velocity of water at the vessel wall on surface concentration of LDL at an arterial wall by means of a computer simulation of convective and diffusive transport of LDL in flowing blood to the wall of a straight artery under conditions of a steady flow. It was found that under normal physiologic conditions prevailing in the human arterial system, due to the presence of a filtration flow of water at the vessel wall, flow-dependent concentration polarization (accumulation or depletion) of LDL occurs at a blood/endothelium boundary. The surface concentration of LDL at an arterial wall takes higher values than that in the bulk flow in that vessel, and it is affected by three major factors, that is, wall shear rate, gamma w, filtration velocity of water at the vessel wall, Vw, and the distance from the entrance of the artery, L. It increases with increasing Vw and L, and decreasing gamma w hence the flow rate. Thus, under certain circumstances, the surface concentration of LDL could rise locally to a value which is several times higher than that in the bulk flow, or drop locally to a value even lower than a critical concentration for the maintenance of normal functions and survival of cells forming the vessel wall. These results suggest the possibility that all the vascular phenomena such as the localization of atherosclerotic lesions and intimal hyperplasia, formation of cerebral aneurysms, and adaptive changes of lumen diameter and wall structure of arteries and veins to certain changes in hemodynamic conditions in the circulation are governed by this flow-dependent concentration polarization of LDL which carry cholesterol.

Flow-dependent concentration polarization of plasma proteins at the luminal surface of a semipermeable membrane

The effect of steady shear flow on concentration polarization of plasma proteins and lipoproteins at the luminal surface of a semipermeable vessel wall was studied experimentally using suspensions of these molecules in a cell culture medium and a semipermeable membrane dialysis tube which served as a model of an implanted vascular graft or an artery. The study was carried out by flowing a cell culture medium containing fetal calf serum or bovine plasma lipoproteins or bovine albumin through a 7.5 mm diameter, 60 mm-long dialysis tube in steady flow under a physiologic mean arterial perfusion pressure of 100 mmHg, and measuring the filtration velocity of water (cell culture medium) at the vessel wall which varied as a consequence of the change in concentration of plasma protein particles at the luminal surface of the semipermeable membrane dialysis tube. It was found that for perfusates containing plasma proteins and/or lipoproteins, filtration velocity of water was the lowest in the absence of flow, and it increased or decreased as the flow rate (hence wall shear rate) increased or decreased from a certain non-zero value, indicating that surface concentration of protein particles varied reversibly as a direct function of flow rate. It was also found that at particle concentrations equivalent to those found in a culture medium containing serum at 5% by volume, plasma lipoproteins which were much smaller in number and lower in concentration but larger in size than albumin, had a much larger effect on the filtration velocity of water than albumin. These findings were very much the same as those previously obtained with a cultured endothelial cell monolayer, strongly suggesting that the flow-dependent variation in filtration velocity of water at a vessel wall results from a physical phenomenon, that is, flow-dependent concentration polarization of low density lipoproteins at the luminal surface of the endothelial cell monolayer.

[A case with infectious mononucleosis-like syndrome caused by human herpes virus-6 infection]

A 26-year-old female was admitted because of multiple fractures in lower extremities. While in the hospital, she developed a high fever and generalized skin eruption. Physical examination revealed bilateral cervical lymphadenopathy and mild hepatosplenomegaly. The white cell count was 11,200 with 11% atypical lymphocytes. Serum GOT, GPT, LDH were markedly elevated. Infectious mononucleosis was suspected, but the serological test for EB virus did not show evidence of acute EB virus infection. Anti-HSV, CMV, hepatitis A virus antibody titers also did not show significant change during the coarse. The serological test for HHV-6 only showed increased titer of IgM and IgG antibodies. Rapidly elevated IgG antibody titer was indicative of reactivation of HHV-6. So, she was diagnosed as mononucleosis-like syndrome caused by HHV-6, probably reactivated infection. Her symptoms gradually disappeared during a month.

[Clinical analysis of community-acquired pneumonia requiring hospitalization in a community hospital--comparison of elderly and non-elderly patients]

A comparative study of 890 patients with community-acquired pneumonia requiring hospitalization in a community hospital was performed. The patients were divided into an elderly patient group and a non-elderly patient group. The elderly patients with community-acquired pneumonia exhibited frequent atypical symptoms such as dyspnea, consciousness disturbance and complication of shock, and also were frequently in a poor nutritional condition. The causative microorganism was isolated in 40.8% of the elderly patients and in 44.0% of the non-elderly patients. Polymicrobial agents were detected frequently in the elderly patients. Streptococcus pneumoniae (19.4%), MSSA (16.8%), Klebsiella pneumoniae (15.1%) and Haemophilus influenzae (15.0%) were frequently isolated from the sputum of the elderly patients, while Mycoplasma pneumoniae (25.2%), H. influenzae (15.0%), S. pneumoniae (12.2%) and MSSA (10.2%) were frequently isolated from that of the non-elderly patients. Regarding treatment with antibiotics, therapy with a single antibiotic therapy, such as cephem or carbapenem was carried out for the elderly patients, while new quinolone or tetracycline was administered to the non-elderly patients. Although the treatment with antibiotics was adequate according to the guidelines of the American Thoracic Society, the prognosis was poor; i.e.) in the elderly patients an efficacy rate of 74.3% and a mortality rate of 9.5%. In the non-elderly patients, the prognosis was good; i.e.) an efficacy rate of 88.0% and a mortality rate of 1.7%. These results suggest that the most important factors affecting the prognosis were the general condition of elderly patients and delay in an adequate diagnosis and treatment because of atypical clinical findings.

[Clinical analysis of pneumonia in the elderly in a community hospital--comparison of community-acquired pneumonia and nosocomial pneumonia]

We experienced 530 elderly cases with pneumonia among 930 patients with pneumonia in Kawasaki Medical School Kawasaki Hospital between April 1986 and September 1998. Clinical analysis of all these patients and a comparison of one group consisting of 418 patients with community-acquired pneumonia and another group composed of 112 patients with nosocomial pneumonia were performed. In all of the elderly patients with pneumonia, respiratory symptoms and inflammatory findings were less frequent, but were frequent for those in poor general and nutritional condition. The causative microorganism was isolated in 42% of these patients. Streptococcus pneumoniae, MSSA and Klebsiella pneumoniae were frequently isolated from the sputum of the patients with community-acquired pneumonia, while Methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, Methicillin-sensitive Staphylococcus aureus (MSSA) were frequently isolated from that of nosocomial pneumonia patients. Mycoplasma pneumoniae, Chlamydia pneumoniae and some viruses were less frequent for patients in both groups. Although many intravenous antibiotics, such as cephem or carbapenem were administered to patients in both groups, the prognosis was relatively good for those with community acquired pneumonia but was extremely poor for those with nosocomial pneumonia despite mechanical ventilation or steroid pulse therapy for many patients.

[Clinical analysis of the prognosis of severe pneumonia requiring mechanical ventilation]

To determine which factors are important in predicting the outcome of patients with severe pneumonia requiring mechanical ventilation, we compared 43 surviving pneumonic patients with 37 non-surviving pneumonic patients. The following results were obtained. The following characteristics were noted in the non-surviving patients as compared with surviving patients; 1. a worsening of performance status in the background, 2. presence of physical signs such as hypotension and trachycardia, 3. abnormal laboratory data such as leukocytosis, lymphocytopenia, hypoalbuminemia, hepatorenal dysfunction and metabolic acidosis, 4. presence of massive pulmonary infiltrations on chest roentgenograms, 5. a prevalence of resistant microorganisms for many antibiotics such as MRSA (Methicillin resistant Staphylococcus aureus). These results suggest that the most important factor affecting the prognosis of patients with severe pneumonia requiring mechanical ventilation may by the condition of the host and of the microorganisms rather than antibiotic treatment.

[Three cases of pneumonia due to mixed infection of bacteria and Mycoplasma pneumoniae]

We reported three cases of pneumonia due to mixed infection of bacteria (2 cases: Streptococcus pneumoniae, 1 case: methicilline-sensitive Stapholococcus aureus) and Mycoplasma pneumoniae. Increased serum antibody titers of M. pneumoniae were noted in all cases. They were a 36-year-old-female with bronchial asthma, a 74-year-old-male with old pulmonary tuberculosis and a 82-year-old-male with chronic bronchitis. All cases had fever, productive cough with purulent sputum and coarse crackle by auscultation. Leukocytosis was noted in 2 cases. Chest X-ray films showed dense consolidation in all cases, 2 cases were cured by administration of cephems and 1 case was cured by administration of carbapenems and minocycline.

[A case with chronic active EB virus infection accompanied with pulmonary candidiasis]

A 44-year-old woman with a history of intermittent fever for several years was admitted because of burn on her leg. On admission, she had hepatosplenomegaly and fever. Antibiotic therapy was started for bacterial infection of the burn. She lost her appetite and IVH was started. During the treatment, high fever appeared and chest X-ray films showed multiple nodular infiltrates throughout both lung fields. Candida albicans was isolated from IVH catheter culture and pulmonary candidiasis was suspected. Her fever and lung involvements were successfully treated with fluconazole. During the course, serum anti-EB-VCA-IgG antibody persisted at a high titer and anti-EBNA antibody remained negative. EB virus DNA was detected in the peripheral blood and bone marrow. Thus, she was diagnosed as chronic active EB virus infection.

[Nosocomial pneumonia experienced in a community hospital]

To clarify the characteristic features of nosocomial pneumonia in a community hospital, we performed a clinical analysis of 147 patients (155 episodes) with nosocomial pneumonia. The following results were obtained. 1, Regarding the risk factors for nosocomial pneumonia, factors such as the patient whose age was over 65 years, a duration of admission of over one month, performance status 4 and underlying respiratory diseases associated with the appearance of nosocomial pneumonia. 2, The causative microorganism isolated from the sputum of the patient with nosocomial pneumonia was frequently a multi-drug resistant microorganism such as Methicillin-resistant Staphylococcus aureus (MRSA). 3, regarding treatment, although several antibiotics were administered for a long time, mechanical ventilation was used on 31% of the patients, and steroid pulse therapy was carried out on 24%. The clinical efficacy was poor with a 50% mortality rate. The reason why treatment of nosocomial pneumonia was difficult is thought to be been related to the general condition of these inpatients and to the appearance of a multi-drug resistant, polymicrobial microorganisms.

[Clinical analysis of patients with nosocomial pneumonia during mechanical ventilation (so-called ventilator-associated pneumonia)]

To clarify the clinical features of nosocomial pneumonia during mechanical ventilation (ventilator-associated pneumonia) and to select the appropriate antibiotic therapy for patients, we performed a clinical analysis of 19 patients (26 episodes) with this condition. The following results were obtained. 1, The average age of the patients was 68 years old (male 16, female 3). 2, VAP occurred three times in 2 cases, twice in 3 cases, and once in 14 cases. 3, The duration of mechanical ventilation was from 7 days to 11 years and 5 months (the average was 2.1 years). 4, The microorganism isolated from the aspiration sputum of the VAP patients was Pseudomonas aeruginosa frequently, but it was difficult to determine whether this microorganism was the causative microorganism. Ten strains of Staphylococcus aureus (MRSA seven strains and MSSA three strains) were newly isolated at the same time as VAP and especially in the cases in which these were thought to be causative microrganisms, all the patients died within a short time. 5, Antibiotics were clinically effective for 53.8% of all the VAP patients and carbapenem antibiotics (for example, IPM/CS) were also used for the effective group. 6, Regarding the risk factors for VAP, factors such as the duration of mechanical ventilation, the existence of chronic obstructive pulmonary disease, a hyponutritional state, prior antibiotics, aspiration of gastric contents, histamine-type-2 receptor antagonist, and multiple organ failure showed significant differences and were suspected to be associated with the appearance of VAP.

High proportion of missense mutations of the BRCA1 and BRCA2 genes in Japanese breast cancer families

Mutations in either of two recently identified genes, BRCA1 and BRCA2, are thought to be responsible for approximately two-thirds of all cases of autosomal-dominantly inherited breast cancer. To examine the nature and frequency of BRCA1 and BRCA2 mutations in Japanese families exhibiting a high incidence of breast cancer, we screened 78 unrelated families in this category for mutations of these two genes. Examining the entire coding sequences as well as exon-intron boundaries of both genes by polymerase chain reaction (PCR) single-strand conformation polymorphism (SSCP) and multiplex-SSCP analysis, we identified possible disease-causing alterations in BRCA1 among affected members of 15 families and in BRCA2 in another 14 families. In 15 of those 29 families, the affected individuals carried missense mutations, although most germline mutations reported worldwide have been deletions or nonsense mutations. Our results, indicating that missense mutations of BRCA1 and BRCA2 tend to predominate over frameshifts or nonsense mutations in Japanese breast cancer families, will contribute significantly to an understanding of mammary tumorigenesis in Japan, and will be of vital importance for future genetic testing.

[Human parvovirus B19-induced aplastic crisis in a case with spherocytosis]

A 43-year-old female with spherocytosis was admitted to the hospital because of fever, headache, and rapidly progressive anemia. On admission, she had severe anemia (Hb 3.9 g/dl) with marked decrease in reticulocytes (0.3%). Some premature leukocytes, such as promyerocyte, were observed in the peripheral blood. Bone marrow smear revealed normocellular marrow with normal presence of erythroid cells. Anti-human parvovirus B19 IgM and IgG antibody was positive in the serum on admission. The DNA of the virus was also detected in the peripheral blood by PCR assay. Thus, this case was diagnosed as acute aplastic crisis caused by human parvovirus B19 infection. Blood transfusion was performed on day 1 and day 2. The symptoms gradually disappeared and increase in reticulocyte (11.5%) was observed on day 5. Premature leukocytes in the peripheral blood disappeared on day 2. She recovered from anemia and was discharged on day 7.

Microcinematographic studies of flow patterns in the excised rabbit aorta and its major branches

Arterial fluid mechanics may play a role as a localizing factor for early atherosclerosis. Flow patterns in natural rabbit aortas rendered transparent were studied using a microcinematographic visualization technique. The aortic arch exhibited a single cell of clockwise-rotating helical secondary flow along the ventral and inner walls. Flow separation occurred proximal to the two arch branches with flow reversal proximal to the brachiocephalic artery. Sinusoidal flow rendered the helical motion more pronounced in systole, while the reverse flow zone periodically expanded and contracted. Steady flow in the abdominal aorta revealed streamlines which follow slow looping trajectories lateral to ostia before tracing helical paths into the branches. Flow separation was present along the dorsal wall of the aorta opposite the superior mesenteric artery. With the exception of the left renal artery, steady flow wall shear stresses were higher distal to ostia than proximal. Spatial gradients of wall shear stress were larger around branches than elsewhere. Similar to observed flow patterns, sites of enhanced macromolecular permeability, as observed previously in the normal rabbit aorta, follow a clockwise helical pattern in the arch and exhibit a distribution around ostia that correlates to some degree with regions of elevated shear stress gradients.

Biopharmaceutical studies on drug/conjugated-metabolite interactions. III. Effect of acetaminophen sulfate and its positional isomers on the pharmacokinetics of acetaminophen in rats

The effect of three positional isomers, o-, m- and p-acetylaminophenyl sulfate (AOAPS, AMAPS and APAPS (acetaminophen sulfate), respectively), on the pharmacokinetics of acetaminophen (APAP) was investigated in rats. All of the intravenously administered positional isomers were rapidly eliminated from plasma, and approximately 80% of the dose was excreted in an unchanged form in the urine within 4 h, while biliary excretions represented a small percent of the doses. Following the intravenous bolus injection of APAP, plasma elimination of APAP was accelerated and the distribution volume of APAP was increased under a steady state concentration (about 10 microg APAP eq/ml) of AOAPS or APAPS, but not AMAPS, as compared with saline infusion. Total body clearances of APAP were increased from 18.3 ml/min/kg for the control to 23.9 and 26.9 ml/min/kg for AOAPS and APAPS coadministration, respectively. AOAPS and APAPS competitively displaced the serum protein binding of APAP, while AMAPS had little effect. The distribution volume of unbound APAP was anomalously increased by APAPS, while it was not affected by AOAPS or AMAPS. Tissue-to-plasma concentration ratios of APAP were significantly increased by APAPS in the liver, kidney and brain, while they were only slightly increased by AOAPS. It was suggested that APAPS has not only the displacing activity of serum protein binding but also other specific effectiveness on the distribution of APAP.

Effect of aluminum ion on Fe(2+)-induced lipid peroxidation in phospholipid liposomes under acidic conditions

The effects of Al3+ on Fe(2+)-induced lipid peroxidation in phospholipid liposomes consisting of phosphatidylcholine (PC) and phosphatidylserine (PS) were examined under acidic conditions. The stimulatory effect of Al3+ on Fe(2+)-induced lipid peroxidation in the liposomes showed a biphasic response against pH variation, and the maximum stimulation was observed around pH 6.0. In addition, it was found that the stimulatory effect of Al3+ on the lipid peroxidation was dependent on the proportion of PS in the liposomes. On the other hand, the lipid peroxidation in PC liposomes was not stimulated by the addition of Al3+. From these findings, it is suggested that the Al3+ effect on Fe(2+)-induced lipid peroxidation under acidic conditions is largely dependent on the phospholipid composition. Trivalent cations such as Tb3+ and Ga3+ also stimulated Fe(2+)-induced lipid peroxidation in PC/PS liposomes under acidic conditions, but divalent cations (Zn2+ and Mn2+) showed no stimulatory effect. The extents of Fe2+ disappearance and Fe3+ formation during the reaction were enhanced by the addition of Al3+ or Ga2+, but Tb3+ had no effect on Fe2+ disappearance. The results with 1,6-diphenyl-1,3,5-hexatriene (DPH) showed that the fluorescence anisotropy of DPH-labeled PC/PS liposomes under acidic conditions was increased by the addition of Al3+. Furthermore, there is a relation between the extents of the fluorescence anisotropy of the complex and TBARS production. In contrast, the fluorescence anisotropy of DPH molecules embedded in PC liposomes was not changed by the addition of Al3+. Based on these results, a possible mechanism of the stimulatory effect of Al3+ on Fe(2+)-induced lipid peroxidation under acidic conditions is discussed.

Flow patterns in dog aortic arch under a steady flow condition simulating mid-systole

To elucidate the possible connection between blood flow and localized pathogenesis and the development of atherosclerosis in humans, we studied the flow patterns and the distribution of fluid axial velocity and wall shear stress in the aortic arch in detail. This was done by means of flow visualization and high-speed cinemicrographic techniques, using transparent aortic trees prepared from the dog. Under a steady flow condition at inflow Reynolds numbers of 700-1600, which simulated physiologic conditions at early- to mid-systole, slow, spiral secondary, and recirculation flows formed along the left anterior wall of the aortic arch and at the entrance of each side branch adjacent to the vessel wall opposite the flow divider, respectively. The flow in the aortic arch consisted of three major components, namely, an undisturbed parallel flow located close to the common median plane of the arched aorta and its side branches, a clockwise rotational flow formed along the left ventral wall, and the main flow to the side branches, located along the right dorsal wall of the ascending aorta. Thus, looking down the aorta from its origin, the flow in the aortic arch appeared as a single helical flow revolving in a clockwise direction. Regions of low wall shear stress were located along the leading edge of each side branch opposite the flow divider where slow recirculation flows formed, and along the left ventral wall where slow spiral secondary flows formed. If we assume that the flow patterns in the human aortic arch well resemble those observed in the dog, then it is likely that atherosclerotic lesions develop preferentially at these sites of low wall shear stress in the same manner as in human coronary and cerebral arteries.

[A case of Plasmodium ovale malaria with thrombocytopenia and an abnormality grade in FDP concentration despite the use of chloroquine as a malaria prophylaxis]

A 45-year-old Japanese male, who had been to the Central African Republic, was admitted to our hospital because of high fever with chills on July 29, 1994. He used chloroquine as a malaria prophylaxis during his stay and for 6 weeks after his return to Japan. On admission, Plasmodium ovale was detected in his blood smears and in the DNA analysis. He was treated successfully with chloroquine (1500 mg over 3 day period) and primaquine (15 mg/day for 14 days beginning day 4). Disappearance of malarial parasites in the peripheral blood smear occurred on the third day and his temperature returned to normal on the 4th day. Interestingly, he had thrombocytopenia and an abnormal grade in fibrin degradation products (FDP) concentration. This led to the suspicion of disseminated intravascular coagulation (DIC). This report indicates the importance of thrombocytopenia which may develop into DIC even though P. ovale malaria infection rarely becomes severe. This is the second report of a P. ovale malaria case in the Central African Republic.

Flow patterns and preferred sites of intimal thickening in end-to-end anastomosed vessels

BACKGROUND

Fluid mechanical factors are suspected to be involved in the pathogenesis and localization of intimal hyperplasia in anastomosed vessels. However, no direct correlation has been established between the flow and the exact sites of intimal hyperplasia. Hence we have studied the relationship between the flow and preferred sites of wall thickening in 90-degree- and 45-degree-cut and end-to-end anastomosed vessels.

METHODS

Twenty-five 90-degree and twenty-five 45-degree end-to-end anastomoses were performed on the femoral arteries of 17 adult mongrel dogs. The vessels were harvested at 3 months after operation, fixed at 100 mm Hg, dehydrated with ethanol, and rendered transparent by immersing them in methyl salicylate. Exact locations and sizes of intimal thickening and characteristics of the flow prevailing at sites of anastomoses were studied in detail by means of flow visualization and cinemicrographic techniques.

RESULTS

It was found that a perfect correlation exists between the preferred sites of intimal thickening and the regions of slow recirculation flows with low wall shear stresses. In both 90-degree and 45-degree anastomosed vessels, intimal thickening developed only in those vessels in which formation of slow recirculation flows was observed. It was also found that although a pronounced and localized intimal thickening developed in 45-degree anastomosed vessels, the degree of circumferential constriction caused by both surgical procedures and development of intimal thickening was much milder in 45-degree than 90-degree anastomosed vessels.

CONCLUSIONS

The results suggest that key hemodynamic factors involved in the localization of intimal thickening in end-to-end anastomosed vessels are low velocity of flowing blood and the resultant low shear stresses acting on the vessel wall.

Luminal surface concentration of lipoprotein (LDL) and its effect on the wall uptake of cholesterol by canine carotid arteries

PURPOSE

The effect of near-wall blood flow velocity and plasma filtration velocity across the arterial wall on luminal surface concentration of low-density lipoproteins (LDL) and the uptake of tritium-cholesterol were investigated.

METHODS

A numeric analysis of LDL transport in steady flow, over the range of physiologically relevant flow rates, predicted a surface concentration of LDL of 4% to 16% greater than that in the bulk flow. The LDL surface concentration increased linearly with filtration velocity and inversely with wall shear rate.

RESULTS

These were validated experimentally in canine carotid arteries. When the transmural pressure was increased from 100 to 200 mm Hg, the filtration velocity increased from 5.13 x 10(-6) cm/sec to 8.41 x 10(-6) cm/sec, whereas the normalized uptake rate of tritium-cholesterol increased from 3.58 x 10(-4) cm/hour to 7.36 x 10(-4) cm/hour.

CONCLUSION

These results indicate that lipids accumulate at the luminal surface in areas where blood flow velocity and wall shear stress are low and where the permeability of the endothelial layer is enhanced. Moreover, the rate of lipid infiltration into the blood vessel walls is affected by the luminal surface concentration. These findings are consistent with chronic hypertension and elevated blood cholesterol concentrations being major risk factors for atherosclerosis.

Stimulation of Fe(2+)-induced lipid peroxidation in phosphatidylcholine liposomes by aluminium ions at physiological pH

The effects of aluminium ions on Fe(2+)-induced lipid peroxidation in egg yolk phosphatidylcholine liposomes were examined under various conditions. The degree of Fe(2+)-induced lipid peroxidation of the liposomes was dependent on pH of the reaction mixture: pH 5.0 > pH 7.4. However, Fe2+ did not induce lipid peroxidation in the liposomes at pH 9.0. The addition of AlCl3 to the liposomal suspension resulted in a marked stimulation of Fe(2+)-induced liposomal peroxidation at pH 7.4, depending on the concentration of AlCl3. On the other hand, Fe3+, Cu2+, Pb2+, Cd2+ and Cr6+ did not induce lipid peroxidation in the liposomes at pH 7.4 regardless of the presence and absence of AlCl3. Fe3+ enhanced Fe(2+)-induced liposomal peroxidation at pH 7.4 but is unrelated to the stimulatory effect of AlCl3. In the absence of AlCl3, Fe(2+)-induced liposomal peroxidation was observed after a lag phase of about 15 min. The lag phase of the reaction was shortened by the addition of AlCl3 in a dose-dependent fashion. The shortening of the lag phase was also observed by the decrease of Fe2+ concentration or by the co-presence of Fe3+ in the reaction mixture. In addition, it was found that AlCl3 stimulates Fe2+ disappearance and Fe3+ formation. The addition of AlCl3 to the liposomal suspension at pH 7.4 resulted in a marked increase of the turbidity of the suspension. On the other hand, the turbidity of the liposomal suspension at pH 5.0 did not change by the addition of AlCl3.(ABSTRACT TRUNCATED AT 250 WORDS)

[Three cases of catamenial pneumothorax]

Three cases of catamenial pneumothorax were presented. A 42-year-old woman with intrapelvic endometriosis had recurrent right-sided pneumothorax with menstruation more than six times. At the operation only a bleb was noted at the apex of the right lung. In a 16-year-old woman who already had been operated on for recurrent right-sided pneumothorax one year ago, left-sided pneumothorax occurred on the day of the beginning of each menstruation four times. A small bleb was noted at the apex. A 29-year-old woman with cesarean section at the age of 25 had recurrent right-sided pneumothorax occurring on the day before the beginning of menstruation three times. Though the operation was performed during her menstrual period, neither air leakage nor any lesions were found. In all cases each lesion was resected and did not prove endometriosis, and partial parietal pleurectomy was performed for pleurodesis. No pneumothorax has recurred.

Flow patterns and spatial distribution of atherosclerotic lesions in human coronary arteries

To investigate the potential role of fluid mechanical factors in the localized genesis and development of atherosclerotic lesions in humans, the exact anatomic locations of atherosclerotic lesions and the flow patterns at such sites in left and right human coronary arteries were studied in detail by flow visualization and high-speed cinemicrographic techniques using five isolated, transparent human coronary arterial trees prepared postmortem. It was found that atherosclerotic plaques and wall thickenings in left and right coronary arteries were localized almost exclusively on the outer wall of one or both daughter vessels at major bifurcations and T-junctions, which left the flow-divider free of lesions, and along the inner wall of curved segments. When flow patterns in such vessels were studied in detail, it was discovered that these sites were where flow was either slow or disturbed with the formation of slow recirculation and secondary flows and where wall shear stress was low. The results indicate that the major hemodynamic factors directly related to the localization of atherosclerotic plaques and wall thickenings in the human arterial system are the low fluid velocity and the resultant low shear stress that acts on the vessel wall.

Flow patterns at the major T-junctions of the dog descending aorta

Using a novel technique developed in our own laboratory, an isolated transparent arterial segment containing the whole descending aorta and its four major branches was prepared from a dog. The flow patterns at each aortic T-junction were studied in detail under the conditions of steady flow by means of flow visualization and cinemicrographic techniques. It was found that a standing recirculation zone consisting of a pair of thin-layered spiral secondary flows located symmetrically about the common median plane of the aorta and side branches was formed at each T-junction over a wide range of flow conditions including the time-averaged estimated mean values of physiological flow rates and flow rate ratios. The results support the recent in vivo findings by other investigators that flow reversal occurs at some junctions of the dog abdominal aorta during each cardiac cycle. The flow patterns at the aortic T-junctions were very much similar to those previously observed in various glass model T-junctions. However, due to the particular anatomical structure of the vessel wall at each branching site (the curvature of the wall was very sharp at the flow divider, but gently rounded at the bend opposite to it) no recirculation zone was formed in the side branches. At a given flow rate ratio, the measured critical Reynolds numbers for the formation of spiral secondary flows and fully developed disturbed flows were much higher in aortic T-junctions than those in glass model T-junctions having equivalent branching angles and diameter ratios. These results indicate that, in the circulation, conditions at arterial T-junctions appear to be optimal for minimizing the formation of disturbed flows.

The effect of angiotensin II on blood flow in tumours during localized hyperthermia

The selective enhancement of drug delivery to tumours is an important factor in the effectiveness of thermochemotherapy as well as in standard normothermal chemotherapy. We have attempted to clarify experimentally using AH 100B tumour-bearing rats whether or not a selective increase in blood flow in tumours can be produced under specific conditions of local hyperthermia by administration of angiotensin (AGT II). AGT II (2 micrograms/kg/min) produced an elevation of blood pressure (ca. 150 mm Hg) when local hyperthermia, at 41, 43, and 45 degrees C, was induced. Furthermore, at 41 and 43 degrees C a selective increase in blood flow in tumours resulted from the AGT II-induced hypertension. By contrast, a decrease in blood flow was observed at 45 degrees C both in tumour and in muscle. These results indicate that AGT II-induced hypertension and the resultant selective increase in drug delivery to tumours during the initial phase of heating may result in an augmentation of the anticancer effects of thermochemotherapy.

Primary retroperitoneal teratoma in an adult: ultrasonographic, computer tomographic and magnetic resonance imaging demonstrations

A 25-year-old male patient with a primary retroperitoneal teratoma is described. The chief complaint was right hypochondralgia during exercise for seven days. Various diagnostic imagings disclosed an expansive, heterogeneous and fat-rich mass associated with multiple cystic lesions in the right suprarenal fossa. Sagittal, transaxial and coronal magnetic resonance imaging scan visualized the extent and character of the tumor very clearly. Histological examination of the tumor removed through a thoracoabdominal approach showed cystic teratoma with out malignant transformations.

Experimental studies of the effects of local hyperthermia on blood flow, oxygen pressure and pH in tumors

The heat-induced environmental changes in tumor tissues are considered to influence the antitumor effect of hyperthermia or hyperthermochemotherapy, which is believed to complement the direct lethal effect of heat on tumor cells. The effects of local hyperthermia on the blood flow, oxygen pressure and pH in tissues were investigated using AH-100B tumor bearing rats, by immersing the tumor in a water bath at 41 degrees, 43 degrees and 45 degrees C. These parameters were measured in the marginal and deeper sites of the tumor mass, and in the normal muscle adjacent to the tumor. During immersion at 41 degrees C, blood flow in the tissue was increased at each site, and during immersion at 43 degrees C, tissue blood flow increased initially at each site, but decreased with time to rates below that of the unheated tissue. During immersion at 45 degrees C, the blood flow decreased markedly in each tissue. The changes in oxygen pressure and pH in each tissue were similar to those observed in the blood flow during localized heating at 41 degrees, 43 degrees and 45 degrees C. In local thermochemotherapy, the initial stage of hyperthermic treatment seems to be the most suitable time for administering carcinostatics, since it is the time when tumor blood flow has not yet decreased.

Microscopic structure of disturbed flows in the arterial and venous systems, and its implication in the localization of vascular diseases

A novel technique to prepare isolated transparent natural blood vessels was developed and used to investigate the connection between blood flow and the localization of vascular diseases in man. Transparent segments of arteries and veins were prepared from dogs and humans postmortem, and the flow patterns in various regions of the circulation were studied in detail by means of flow visualization and cinemicrographic techniques. It was found that under normal physiological conditions, complex spiral secondary flows and recirculation zones form in various regions of the arterial and venous systems such as the aortic arch, aortic T-junctions, carotid artery bifurcations, the major branching sites of the intracranial cerebral arteries and venous valve pockets. Incipient saccular aneurysms were found at the flow divider of the anterior communicating-anterior cerebral artery junction where the flow directly impinged on the vessel wall. In human cerebral arteries, atherosclerotic thickenings of the vessel wall were found to be localized on the outer wall (hip) of one or both daughter vessels at bifurcations and T-junctions, and at the inner wall of arterial bends, at the very places where secondary and recirculation flows were dominant and wall shear stress was low. The results clearly indicate that there is a strong correlation between the sites of flow disturbance and the preferred sites for the genesis and development of vascular diseases clinically found in man.