Aerodynamics of a bio-inspired flexible flapping-wing micro air vehicle

MAVs (micro air vehicles) with a maximal dimension of 15 cm and nominal flight speeds of around 10 m s⁻¹, operate in a Reynolds number regime of 10⁵ or lower, in which most natural flyers including insects, bats and birds fly. Furthermore, due to their light weight and low flight speed, the MAVs' flight characteristics are substantially affected by environmental factors such as wind gust. Like natural flyers, the wing structures of MAVs are often flexible and tend to deform during flight. Consequently, the aero/fluid and structural dynamics of these flyers are closely linked to each other, making the entire flight vehicle difficult to analyze. We have recently developed a hummingbird-inspired, flapping flexible wing MAV with a weight of 2.4-3.0 g and a wingspan of 10-12 cm. In this study, we carry out an integrated study of the flexible wing aerodynamics of this flapping MAV by combining an in-house computational fluid dynamic (CFD) method and wind tunnel experiments. A CFD model that has a realistic wing planform and can mimic realistic flexible wing kinematics is established, which provides a quantitative prediction of unsteady aerodynamics of the four-winged MAV in terms of vortex and wake structures and their relationship with aerodynamic force generation. Wind tunnel experiments further confirm the effectiveness of the clap and fling mechanism employed in this bio-inspired MAV as well as the importance of the wing flexibility in designing small flapping-wing MAVs.

Aerodynamic performance of a hovering hawkmoth with flexible wings: a computational approach

Insect wings are deformable structures that change shape passively and dynamically owing to inertial and aerodynamic forces during flight. It is still unclear how the three-dimensional and passive change of wing kinematics owing to inherent wing flexibility contributes to unsteady aerodynamics and energetics in insect flapping flight. Here, we perform a systematic fluid-structure interaction based analysis on the aerodynamic performance of a hovering hawkmoth, Manduca, with an integrated computational model of a hovering insect with rigid and flexible wings. Aerodynamic performance of flapping wings with passive deformation or prescribed deformation is evaluated in terms of aerodynamic force, power and efficiency. Our results reveal that wing flexibility can increase downwash in wake and hence aerodynamic force: first, a dynamic wing bending is observed, which delays the breakdown of leading edge vortex near the wing tip, responsible for augmenting the aerodynamic force-production; second, a combination of the dynamic change of wing bending and twist favourably modifies the wing kinematics in the distal area, which leads to the aerodynamic force enhancement immediately before stroke reversal. Moreover, an increase in hovering efficiency of the flexible wing is achieved as a result of the wing twist. An extensive study of wing stiffness effect on aerodynamic performance is further conducted through a tuning of Young's modulus and thickness, indicating that insect wing structures may be optimized not only in terms of aerodynamic performance but also dependent on many factors, such as the wing strength, the circulation capability of wing veins and the control of wing movements.

Regio- and stereoselective oxidation of propranolol enantiomers by human CYP2D6, cynomolgus monkey CYP2D17 and marmoset CYP2D19

Toxic and pharmacokinetic profiles of drug candidates are evaluated in vivo often using monkeys as experimental animals, and the data obtained are extrapolated to humans. Well understanding physiological properties, including drug-metabolizing enzymes, of monkeys should increase the accuracy of the extrapolation. The present study was performed to compare regio- and stereoselectivity in the oxidation of propranolol (PL), a chiral substrate, by cytochrome P450 2D (CYP2D) enzymes among humans, cynomolgus monkeys and marmosets. Complimentary DNAs encoding human CYP2D6, cynomolgus monkey CYP2D17 and marmoset CYP2D19 were cloned, and their proteins expressed in a yeast cell expression system. The regio- and stereoselective oxidation of PL enantiomers by yeast cell microsomal fractions were compared. In terms of efficiency of expression in the system, the holo-proteins ranked CYP2D6=CYP2D17>>CYP2D19. This may be caused by the bulky side chain of the amino acid residue at position 119 (leucine for CYP2D19 vs. valine for CYP2D6 and CYP2D17), which can disturb the incorporation of the heme moiety into the active-site cavity. PL enantiomers were oxidized by all of the enzymes mainly into 4-hydroxyproranolol (4-OH-PL), followed by 5-OH-PL and N-desisopropylpropranolol (NDP). In the kinetic analysis, apparent K(m) values were commonly in the μM range and substrate enantioselectivity of R-PL<S-PL was observed in both K(m) and V(max) values for the formation of the three metabolites from PL enantiomers. The activity to produce NDP tended to be higher for the monkey enzymes, particularly CYP2D17, than for the human enzyme. These results indicate that in the oxidation of PL enantiomers by CYP2D enzymes, stereoselectivity is similar but regioselectivity is different between humans and monkeys.

Disease recurrence patterns after R0 resection of hilar cholangiocarcinoma

BACKGROUND

There is little information regarding the clinical behaviour of hilar cholangiocarcinoma after curative resection.

METHODS

A retrospective study was undertaken of 79 consecutive patients with hilar cholangiocarcinoma who had undergone major hepatectomy (three or more Couinaud segments) concomitant with caudate lobectomy, and had negative resection margins. Sites of initial disease recurrence were classified as locoregional (porta hepatis) or distant (intrahepatic, peritoneal, para-aortic lymph nodal or extra-abdominal). Univariable and multivariable analyses were performed to determine the factors potentially related to recurrence.

RESULTS

Disease recurrence was observed in 42 (53 per cent) of the 79 patients. Cumulative recurrence rates at 3 and 4 years after surgery were 52 and 56 per cent respectively. Locoregional recurrence alone was observed in eight (10 per cent) and distant metastasis in 34 (43 per cent) of the 79 patients after R0 resection. Positive nodal involvement and high International Union Against Cancer tumour (T) stage were independent prognostic factors associated with distant metastasis.

CONCLUSION

Distant metastases are more common than locoregional recurrence after R0 resection for hilar cholangiocarcinoma, and associated with nodal involvement and high T stage.

Expression Levels of Enzymes Related to In Situ Estrogen Synthesis and Clinicopathological Parameters in Breast Cancer Patients

Background: Local estrogen synthesis may play an important role of progression of breast cancer with hormone receptors. Local progression of breast cancer may depend on high concentration of estrogens and estrogen receptor status. To clarify correlation between expression levels of enzymes in breast cancer and clinicopathological parameters, we analyzed expression of steroid sulfatase(STS), estrogen sulfatase(EST), 17b-hydroxyl steroid dehydrogenase type I & II(17b-HSDI & II) and aromatase. In addition, mRNA expression of estrogens receptor alpha(ERa), estrogen receptor beta(ERb), cycline D1 and erbB2 were measured. Material and Methods: The mRNA expression levels of genes in 196 breast cancer tissues removed from surgery were assayed by RT-PCR. Results: The level of STS were significantly higher in patients with clinical stage. STS expressed none in stage 0 or I, 0.011 in stage II, and 0.013 amol/1 amol b-actin in stage 3 or 4. In addition, EST expressed 58.5 amol/1 amol b-actin in stage 2 and 36.8 in stage 3 or 4, otherwise, the expression level of EST in stage 0 or 1 revealed 15.3 amol/1 amol b-actin. There were no correlation between clinical stage and aromatase expression. Expression levels of ERa and cyclineD1 significantly correlated with protein levels of ER, and there were significant correlation between erbB2 expression and prognosis of patients. Conclusion: Up-regulation of STS play an important role in tumor progression of breast cancer.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4155.

[Bronchial schwannoma diagnosis by surgical treatment; report of a case]

18-year-old male was referred to our hospital due to persistent cough. The patient was admitted for the investigation of the abnormal shadow on a chest X-ray and chest computed tomography (CT). Chest CT showed a 2.5 cm nodular shadow in the right lower lobe. Bronchofiberscopy revealed the polypoid lesion at the right lower lobe bronchus obstructing the entire lumen of B8-10. The tumor surface was smooth and rich in small vessels. Right lower lobectomy was peformed. The diagnosis of schwannoma was confirmd with the S-100 positive immunohistochemical stain. Bronchial schwannoma is relatively rare disease; less than 90 cases have been reported with respect to schwannoma of case report in Japan.

[Aortic valve replacement for the patient with Osler-Rendu-Weber disease]

Osler Rendu-Weber (O-R W) disease (hereditary haemorrhagic telangiectasia) is characterized by an anormality of the peripheral blood vessels which often causes recurrent epistaxis. We presented a case of aortic valve replacement for the patient with O-R-W disease. A 75-year-old woman diagnosed as O-R-W disease with chest pain and dyspnea was admitted. Preoperative transthoratic echocardiography showed severe aortic valve stenosis (AS) with a pressure gradient (from left ventricle to ascending aorta) of 72.5 mmHg. Urgent aortic valve replacement (AVR) was performed after preoperative hormonal (estrogen-progesterone) therapy, that might be effective for bleeding from vascular ectasia. No hemorrhagic tendency was recognized and the postoperative course was uneventful.

[Surgical treatment for the patient with atrial septal defect and Andersen syndrome]

An 18-year-old girl with atrial septal defect and Andersen syndrome is reported. Andersen syndrome was described as a hereditary disease characterized by periodic paralysis, prolongation of the QT interval with ventricular arrhythmia and characteristic physical features including low set ear and micrognathia. We successfully performed cardiac operation for this rare associated malformation.

[Norwood procedure after colostomy; report of a case]

We encountered a baby who was diagnosed with anal atresia, interruption of aortic arch (type B), aortic stenosis, mitral stenosis, single atrium, large ventricular septal defects, aberrant origin right subclavian artery. We operated on him using the Norwood procedure after a colostomy. Aortic arch was reconstructed by interposing with an 8 mm graft and the right ventricular-pulmonary artery (RV-PA) conduit was chosen for pulmonary flow. We closed the sternum 6 days after the Norwood procedure. We extubated him 16 days after delayed sternal closure. There was no trouble with his stoma and no sign of infection. The postoperative echocardiography didn't show the finding which left pulmonary artery was stenotic, but the lung perfusion schintigraphy revealed an imbalance in the distribution of lung perfusion. He was discharged 70 days after undergoing the Norwood procedure.

[Successful repair of supravalvular aortic stenosis using Steinberg 3 sinuses reconstruction; report of a case]

Steinberg method is a modification of Doty extended aortoplasty for supravalvular aortic stenosis (SAS). This modification entails placement of an additional patch in the left coronary sinus. A 3-year-old boy was diagnosed as SAS with aortic valvular stenosis. He was noticed a systolic murmur from 1 month after his birth. Echocardiography showed left ventricular hypertrophy, and pressure gradient of 80 mmHg was measured between the ascending aorta and the left ventricle. Cardiac catheterization revealed severe aortic stenosis at the sino-tubular (ST) junction. We adopted Steinberg 3 sinuses reconstruction. After this operation, there was no pressure gradient at ST junction although aortic valvular stenosis remained and mild aortic valve regurgitation newly developed. As this method can produce a symmetric aortic root, it may reduce aortic valve deformity especially on the left coronary cusp.

[Surgical treatment for postinfarction ventricular septal perforation]

Between November 1985 and April 2003, surgical treatment for ventricular septal perforation (VSP) after acute myocardial infarction was performed in 16 patients. Patients were divided into 2 groups by method of operation. One group is infarct exclusion technique (n = 10). The other group is trans right ventricular (RV) approach (n = 6). No significant differences were observed between 2 groups in preoperative states. Operative death rate was high in both groups. Five patients (50%) were died in infarct exclusion group, 4 patients (67%) in trans RV group. Infarct exclusion technique needed longer extracorporeal circulation time (201 +/- 33 min) than trans RV approach (170 +/- 32 min). Although trans RV approach is attractive for its simplicity, 3 cases died of rupture of remained left ventricle infarction area. On the other hand, there were no mortality cases caused by left ventricle rupture in infarct exclusion technique group. As this result, we select infarct exclusion technique as a surgical correction for VSP.

[Primary malignant pericardial mesothelioma temporarily reduced by radiation therapy: a case report]

A 47-year-old woman was referred to our hospital because of cardiomegaly and pericardial effusion. She complained of a cough. Computed tomography, echocardiography, and magnetic resonance imaging showed a mass on the pericardium. Exploratory surgery revealed a solid tumor invading the pericardium over the aortic arch and main pulmonary artery. Histological examination indicated primary malignant pericardial mesothelioma. After 58 Gy radiation, the size of the tumor was temporarily reduced and the patient's symptoms disappeared. However, the tumor enlarged and her symptoms reappeared 7 months after temporary improvement. Eighteen months after the development of cough, the patient died suddenly.

Atomic force microscope of drug-DNA interaction

We have been investigated the possibility of B-Z transition in ZnTMPyP-DNA interaction based on the observation of spectroscopic data. In this study, we found drastic change in the AFM image of supercoiled plasmid DNA when it was interacted with TMPyPs indicating that the considerable amount of unwinding of double helix or B-Z transition is induced by the drug-DNA interaction. Such phenomena were not observed for other cationic drugs examined.

[Total aortic arch replacement with a right femur neck fracture on chronic renal dialysis; report of a successful case]

Although recent operative outcome for aortic arch aneurysm has been improved by various newly-devised assistant measures, satisfactory results have not been obtained in cases with serious preoperative complications, such as chronic renal failure. We present here an operative case of a 67-year-old woman on chronic hemodialysis with a calcified aortic arch aneurysm and a right femur neck fracture. First, we performed femur head replacement under careful hemodynamic control. After her mobilization was achieved, total aortic arch replacement was performed in "arch-first technique" using deep hypothermia plus retrograde cerebral perfusion in consideration of her calcified vessels. Her postoperative course was uneventful. We believe that early mobilization was a key for her recovery, because it was useful to prevent postoperative complications such as pulmonary infection and atelectasis. Our experience suggested that meticulous management throughout the whole perioperative course is very important for total aortic arch replacement in such complicated cases.

[Surgical treatment for giant ascending aorta-arch aneurysm coexisted with DeBakey type II dissection on elderly women: report of a case]

A 78-year-old woman was admitted to our hospital after computed tomography (CT) had revealed in her the presence of a giant ascending aorta-arch aneurysm. This aneurysm was about 8 cm in diameter and associated with DeBakey type II dissection. Aortography showed the same condition as the CT view with the entry on the ascending aorta. The ascending aortaarch was replaced with a Hemashield 24 mm, by using deep-hypothermic selective cerebral perfusion and the open distal method. There were no complications during her peripostoperative state and no evidence of leakage and remnant dissection on CT and aortography. This is a rare case in which thoracic aortic aneurysm coexisted with dissection. In this case of severe atherosclerosis, deep-hypothermic selective cerebral perfusion and the open distal method provided effective treatment.

Quantitative assessment of right ventricular structural abnormalities by right ventricular polar mapping of single photon emission computed tomogram

The identification of right ventricular (RV) abnormalities is clinically important in the evaluation of arrhythmogenic substrates in right ventricular-originated ventricular tachycardia (RVT). The purpose of this study was to determine the diagnostic benefit of quantitative analysis in RV single photon emission computed tomography (SPECT) imaging with (99m)Tc-tetrofosmin/sestamibi in patients with RVT. Thirty patients with RVT (15 with idiopathic RVT and 15 with arrhythmogenic right ventricular cardiomyopathy (ARVC)) were compared with 27 control subjects (including 11 with right bundle branch block) with regard to the semiquantitative RV uptake score in each of six segments and the quantitative RV extent score in polar coordinate map displays by SPECT imaging. The RV total score and RV extent score were compared with the RV global function. Perfusion abnormalities were more frequently detected (P = 0.0001) in the ARVC group (59/90, 65.6%) than in the idiopathic RVT group (4/90, 4.4%) or controls (1/162, 0.6%). The RV extent score in the ARVC group (53.0 +/- 24.8) was significantly higher than that in the idiopathic RVT group (8.4 +/- 10.1) or controls (1.2 +/- 4.9). The RV extent score correlated well with the regional RV perfusion score (P < 0.0001) and with the RV ejection fraction (P < 0.0001). Non-invasive RV perfusion mapping using a (99m)Tc-labelled tracer is useful for the quantitative evaluation of RV substrates in patients with ARVC.

Validation of quantitative gated single photon emission computed tomography and an automated scoring system for the assessment of regional left ventricular systolic function

Despite its ability to quantify regional perfusion and function, there is no established method for quantification of regional perfusion and function by myocardial gated single photon emission computed tomography (SPECT). The aim of this study was to establish a quantitative index for regional perfusion and systolic function assessment using gated SPECT. Myocardial SPECT was performed at rest using (99m)Tc sestamibi with 8-frame gating in 62 consecutive patients. In addition to computation of left ventricular ejection fraction (LVEF), a new computerized method for quantifying, displaying and automatically grading regional data was developed. Regional function was quantified as wall motion, regional EF, and imaged based, count based, and normalized per cent wall thickenings (%WTs). Regional perfusion was assessed as a relative per cent peak count. Data were displayed on a 25-segmented polar map and automatically graded with a 5-point scale, and then summed scores were calculated. These quantitative parameters were compared to data from radionuclide ventriculography (RNV) and contrast left ventriculography. Gated SPECT had high reproducibilities for calculating global and regional ejection fractions and %WT indices (r=0.811-0.984, P<0.0001), but measurement of wall motion was less reproducible (r=0.555, SEE=7.9, P<0.011). LVEF estimated by gated SPECT and summed perfusion scores correlated closely (P<0.0001) with angiographic LVEF. Among the summed function indices that correlated closely with LVEF, normalized %WT had the closest correlations with LVEF estimated by RNV (r=0.657, P<0.0001) and by gated SPECT (r=0.778, P<0.0001). Assessment by visual reviewing of cine-mode playback or by normalized %WT had greater overall sensitivity, specificity, and positive and negative predictive values for detecting impaired regional function among the functional parameters: 71%, 79%, 63% and 84% for cine format analysis, and 78%, 73%, 59% and 87% for normalized %WT, respectively. Thus, besides LVEF, quantitative gated SPECT can provide reproducible and reliable quantitative data on regional perfusion and function. Automated summed scores obtained by gated SPECT can reflect integrated abnormalities of regional perfusion and function of the left ventricle. Both visual analyses by cine-mode display and a functional map of normalized wall thickening have greater diagnostic values for detecting regional function deficit related to coronary artery disease.

The role of the hypothalamic nitric oxide in the pressor responses elicited by acute environmental stress in awake rats

We quantitatively investigated the change in nitric oxide (NO) in the hypothalamic paraventricular nucleus (PVN) and its effect on cardiovascular regulation during shaker stress (SS) using brain microdialysis in awake rats. Male Wistar rats were fed either N(G)-nitro-L-arginine methyl ester (L-NAME, 0.7 g/L) or tap water for 2 weeks. Two days after implantation of an arterial catheter and guide shaft, a microdialysis probe was placed to perfuse the PVN with degassed Ringer solution at 2 microl/min in awake normotensive Wistar (CONTROL) and chronic L-NAME-treated hypertensive rats. After the rat was placed in a plastic cage set on a shaker, the blood pressure and heart rate was monitored and 10-min SS was loaded at a frequency of 200 cycles/min. Dialysate samples were analyzed by NO analyzer (based on the Griess reaction) every 10 min, and NOx (NO(2)(-) + NO(3)(-)) was measured. Plasma NOx was also measured before and after SS. Pressor responses elicited by SS were significantly greater in L-NAME-treated rats than in the CONTROL. Although NOx in the PVN dialysate were increased by SS in the CONTROL, these responses were attenuated in chronic L-NAME-treated rats. Resting plasma NOx were higher in the CONTROL than in L-NAME-treated rats. SS elicited no difference between two groups in plasma NOx. These results indicated that NO within the PVN, but not in systemic circulation, may play a role on the attenuation of the pressor responses elicited by SS. The dysfunction of NO release within the PVN may, in part, play a role in the exaggerated pressor responses in acute environmental stress.