Trends in Heart Valve Surgery in Korea: A Report from the Heart Valve Surgery Registry Database

Background

In this study, we present recent trends in heart valve surgery in Korea through analyses of data from the Korea Heart Valve Surgery Registry (KHVSR).

Methods

We enrolled 8,981 patients who were registered in the KHVSR from 2017 to 2020. Yearly trends in patients’ baseline characteristics, surgical profiles, and early mortality rates were explored. The observed/expected mortality ratio (O/E ratio), calculated from the actual mortality in the KHVSR and the predicted mortality estimated using the EuroSCORE II, was also analyzed.

Results

The proportion of aortic valve surgery significantly increased from 56.8% in 2017 to 60.3% in 2020. The proportion of all combined procedures and minimally invasive surgery significantly increased over the 4-year study period. The operative mortality rate was 2.9% in the entire cohort, while mitral valve repair showed the lowest mortality risk (0.9%). The mortality rates of isolated aortic valve replacement (AVR) significantly decreased from 2.1% in 2017 to 0.8% in 2020 (p=0.016). Overall, the O/E ratio was 0.784 (95% confidence interval [CI], 0.677–0.902) demonstrating significantly lower actual mortality risks than expected based on the EuroSCORE II. In particular, the O/E ratios were as low as 0.364 (95% CI, 0.208–0.591) for isolated AVR.

Conclusion

The recent data from the KHVSR showed increasing trends for complex procedures and minimally invasive surgery in heart valve surgery in Korea, and demonstrated remarkably low risks of operative mortality.

Impact of chronic kidney disease on clinical outcomes in patients with Stage B progressive aortic regurgitation (mild to moderate and moderate grades)

Background

Chronic kidney disease (CKD) is a significant comorbidity in patients with heart failure and valvular heart disease. Renal impairment is not well evaluated in the patients with Stage B progressive aortic regurgitation (AR) (mild to moderate and moderate grades in this study), for estimating outcome.

Hypothesis

We sought to investigate the prognostic factor, especially CKD, in the patients with progressive AR.

Methods

We enrolled 262 patients with Stage B progressive AR and preserved left ventricular systolic function (ejection fraction ≥ 50%). Based on the presence of CKD, the patients were divided into CKD (n = 70) and non‐CKD (n = 192) groups, which CKD was defined as estimated glomerular filtration rate < 60 ml/min/1.73 m². The primary outcome was major adverse cardiac events (MACEs), including cardiac death, myocardial infarction, hospitalization for heart failure, and aortic valve replacement.

Results

The median follow‐up duration was 41.5 (interquartile range: 16.2–71.7) months. Between groups, the CKD patients were older; they had a higher pulse pressure and higher incidence of hypertension, diabetes mellitus, dyslipidemia, cerebrovascular accident, and atrial fibrillation. Compared to the non‐CKD group, the CKD group had lower eʹ velocity (4.36 ± 2.21 vs. 5.20 ± 2.30 cm/s, p = .009), higher right ventricular systolic pressure (38.02 ± 15.79 vs. 33.86 ± 11.77 mmHg, p = .047). The CKD group was associated with increased risk of MACEs (41.4% vs. 22.4%; unadjusted hazard ratio [HR]: 1.78, 95% confidence interval [CI]: 1.11–2.85, p = .017). In multivariate Cox regression analyses, the risk of MACEs was significantly different between groups (adjusted HR: 1.71, 95% CI: 1.11–2.62, p = .015); furthermore, the risk of hospitalization for heart failure (10.0% vs. 2.6%; adjusted HR: 2.30, 95% CI: 1.16–4.55, p = .017) was significantly higher in the CKD group than in the non‐CKD group.

Conclusions

In patients with Stage B progressive AR, CKD is an independent prognostic factor for clinical outcomes (composite clinical outcome, hospitalization for heart failure).

Chronic kidney disease is a known comorbidity for valvular heart disease.

We investigated that chronic kidney disease was an independent prognostic factor for clinical outcomes (composite clinical outcome and hospitalization for heart failure) in patients with Stage B progressive aortic regurgitation.

Although Stage B progressive aortic regurgitation should be carefully monitored in all patients by guideline, special attention should be paid to patients with pre‐existing chronic kidney disease.

Idiopathic hypereosinophilic syndrome with intracardiac atypical linear-shaped and floating thrombus presenting as embolic cerebral infarction

Knowledge of the multi-organ involvement in hypereosinophilic syndrome (HES) is important for the diagnosis and care of patients with this condition, even in cases with atypical presentation. This report aims to describe cerebral embolic infarction and intracardiac atypical linear-shaped thrombus in a patient with idiopathic HES and to discuss the approach of appropriate diagnosis and timely interventional management. A 55-year-old man presented with general weakness, including left-sided weakness, mild cognitive dysfunction, and mild exertional dyspnea for about 2 weeks. Initial magnetic resonance imaging for evaluating the brain showed multifocal acute to subacute infarction of both cerebral hemispheres and both cerebellums. Laboratory findings revealed leukocytosis (25,620 cells/mm³) and eosinophilia (54.9%). To evaluate the intracardiac embolic source, the patient underwent echocardiography, and a 1.5 cm linear thread-like and mobile mass was detected. Consequently, the patient was diagnosed with idiopathic HES. After bone marrow biopsy, corticosteroid and hydroxyurea were administered to control the eosinophilia. This case indicates that HES can present as a floating intracardiac atypical linear-shaped thrombus attached to the left ventricle. After appropriate diagnostic approaches, proper treatment could be given for the patient. <Learning objective: Idiopathic hypereosinophilic syndrome (HES) is a disorder characterized by persistent eosinophilia with heterogeneous clinical manifestations. Knowledge of the multi-organ involvement in HES is important for the diagnosis and care of patients with this condition, even in cases with atypical shaped thrombus as clinical presentation. Close monitoring combined with early treatment and diagnosis may help reduce mortality in HES patients.>.

Cardiac impalement injury by a steel rebar: A case report

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Cardiac impalement injuries may be fatal.

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We report a patient with cardiac injury due to penetration by a steel rebar.

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The patient also sustained pulmonary injuries.

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The steel rebar was pulled out gradually during cardiopulmonary bypass (CPB).

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CPB is an effective surgical treatment even if there is a risk of bleeding.

Introduction

Penetrating cardiac injury often occurs in South Korea. However, impalement injury of the heart with other organs is rare and fatal. We present a case of cardiac impalement injury by a steel rebar.

Presentation of case

A 38-year-old man was brought to the emergency room with a steel rebar of 45.5 cm in length in situ. Chest tomography revealed that the rebar had entered the thorax to the right diaphragm via the left shoulder while piercing the heart. The patient was immediately taken to the operating room for surgery without removing the bar. We were able to rescue the patient with an emergency operation wherein the bleeding site was treated by pulling the steel rebar out step-by-step while performing cardiopulmonary bypass.

Discussion

Early diagnosis and rapid surgery are important factors for patients with cardiac impalement injury. Haemostasis must be achieved patiently step- by- step without removing the foreign object at once. CPB is an appropriate treatment, even if there is a risk of bleeding.

Conclusion

This case highlights the importance of immediate surgical treatment for the survival of severe thoracic impalemant injury patients.

Multi-Modality Imaging of Coronary Artery Fistula with Giant Aneurysms

A 50-year-old woman was referred to our hospital with a chief complaint of chest pain. Coronary angiography revealed a fistula between the left anterior descending artery and pulmonary artery with giant aneurysms. Although coronary angiography is considered the standard tool to confirm a coronary artery fistula, the patient in this case underwent successful surgical repair with the aid of multi-modality imaging.

Use of a gamma-2 herpesvirus as a vector to deliver antibodies to rhesus monkeys

The gamma-2 herpesvirus of rhesus monkeys, rhesus monkey rhadinovirus (RRV), persists principally in B cells of its host. We constructed recombinant strains of RRV expressing the rhesus monkey-derived anti-SIV monoclonal antibodies 4L6 and 5L7 and compared the RRV-mediated in vivo delivery of these antibodies in rhesus monkeys with previous studies that utilized intramuscular delivery with an adeno-associated virus (AAV) vector. Recombinant RRV-4L6 and RRV-5L7 were both shown to stably produce the antibodies in persistently infected B-cell lines in culture. Two RRV-negative rhesus monkeys were experimentally infected with recombinant RRV-4L6 and two with recombinant RRV-5L7. Following infection, the appearance of the delivered antibody was readily detected in all four animals. However, the levels of the delivered antibody were considerably lower than what has been typically observed following intramuscular AAV delivery. Furthermore, three of the four monkeys had an antibody response to the delivered antibody as had been observed previously with intramuscular AAV delivery of these same antibodies. We conclude that this recombinant herpesvirus has no inherent advantage over AAV for delivery of potentially therapeutic monoclonal antibodies in a rhesus monkey model.

Isolated metastasis of hepatocellular carcinoma in the right ventricle: A case report

Metastatic hepatocellular carcinoma (HCC) of the right ventricle is very rare and difficult to diagnosis.A 79-year-old man who underwent right hemi-hepatectomy for HCC was admitted to our hospital for chest pain, severe dyspnea, and orthopnea. The echocardiogram showed a tumor located in the right ventricle. A biopsy was obtained, and histopathological findings confirmed metastatic HCC. Palliative resection of the tumor was performed.There is no standard treatment for metastatic HCC into the right ventricle. Thus, treatment should be individualized to the patient, and a multidisciplinary approach should be used.

Inexplicable Outcome of Early Appearance of Hepatocellular Carcinoma in the Allograft After Deceased Donor Liver Transplantation: A Case Report

BACKGROUND

This case represents the earliest appearance of de novo HCC after liver transplantation (OLT) compared with cases of previously reported literatures.

CASE REPORT

A 45-year-old man underwent deceased donor OLT owing to decompensated liver cirrhosis. He had YMDD viral mutation and hepatitis B (HBV) and C (HCV) coinfection but no tumor was found in the liver on MRI before OLT. The donor was a healthy young female donor who was HCV and HBV negative. There was no tumor in the explant liver. After OLT, HCV RNA and hepatitis B surface antigen became undetectable with DNA-positive HBV. Nine months after OLT, a computed tomography (CT) scan was performed owing to abdominal pain, detecting a mass occupying the right lobe that depicted enhanced characteristics typical of HCC. The chest CT demonstrated metastatic lung nodules in the right basal lower lobe. Fluorescence in situ hybridization showed tumor cells from the recipient.

CONCLUSIONS

To the best of our knowledge, this is the first report of de novo hepatocellular carcinoma that has emerged within a short period of undergoing OLT.

Prediction of Intimal Tear Site by Computed Tomography in Acute Aortic Dissection Type A

Background and Objectives

Preoperative identification of intimal tear site in acute type A dissection will help procedural planning. The objective of this study was to determine the key findings of computed tomography (CT)-based prediction for tear site and compare the accuracy between radiologists and surgeons.

Subjects and Methods

Multi-detector CT (MDCT) images from 50 patients who underwent surgical repair of type A aortic dissection were retrospectively reviewed by 4 cardiac surgeons with limited experience or by 3 radiologists specialized in cardiovascular imaging. Surgical findings of intimal tear site were used as references.

Results

In surgical findings, the locations of intimal tear that were identified in 43 patients included aorta (n=25), ascending with arch (n=7), and arch only (n=11). The rest were retrograde dissections from the tear of descending aorta. Key CT findings that were most frequently found were defect in the intimal flap shadow (30.0±4.0 patients/reviewer, accuracy 87.0±11.7%) and differential filling of false lumen by phase and location (9.4±2.9 patients/reviewer, 84.8±10.4%). Surgeons predicted tear site (75.0±7.7% vs. 86.7±1.2%, p=0.055) and specified flap defect (80.5±10.3% vs. 95.7±7.4%, p=0.073) with lower accuracy than radiologists.

Conclusions

With MDCT imaging, well-educated surgeons could be accurate in three fourths of cases. There was room for improvement through experience. Considering the substantial possibility of inaccuracy, critical decisions on CT images should be made through thorough reviewing by as many experienced radiologists and surgeons as possible.

Change of Proximal Descending Aortic False Lumen after Conventional Repair of Acute Type I Dissection: Is It Always Unfavorable?

Background

Some patients show favorable changes in the descending aortic false lumen after conventional repair of acute type A dissection, although the incidence of favorable changes has been reported to be low. We aimed to investigate the incidence of positive postoperative changes in the false lumen and the factors associated with positive outcomes.

Methods

In 63 patients who underwent surgery for type A acute dissection as well as serial computed tomography (CT) scanning, morphological parameters were compared between the preoperative, early postoperative (mean interval, 5.4 days), and late CT scans (mean interval, 31.0 months) at three levels of the descending thoracic aorta.

Results

In the early postoperative CT images, complete false lumen thrombosis and/or true lumen expansion at the proximal descending aorta was observed in 46% of the patients. In the late images, complete thrombosis or resolution of the proximal descending false lumen occurred in 42.9% of the patients. Multivariate analysis found that juxta-anastomotic false lumen thrombosis was predictive of favorable early changes, which were in turn predictive of continuing later improvement.

Conclusion

Even after conventional repair without inserting a frozen elephant trunk, the proximal descending aortic false lumen showed positive remodeling in a substantial number of patients. We believe that the long-term prognosis of type A dissection can be improved by refining surgical technique, and particularly by avoiding large intimal tears at the anastomosis site during the initial repair.

Sternal healing after coronary artery bypass grafting using bilateral internal thoracic arteries: assessment by computed tomography scan

Background

This study aimed to investigate sternal healing over time and the incidence of poor sternal healing in patients undergoing coronary artery bypass graft (CABG) surgery using bilateral internal thoracic arteries.

Methods

This study enrolled 197 patients who underwent isolated CABG using skeletonized bilateral internal thoracic arteries (sBITA) from 2006 through 2009. Postoperative computed tomography (CT) angiography was performed on all patients at monthly intervals for three to six months after surgery. In 108 patients, an additional CT study was performed 24 to 48 months after surgery. The axial CT images were used to score sternal fusion at the manubrium, the upper sternum, and the lower sternum. These scores were added to evaluate overall healing: a score of 0 to 1 reflected poor healing, a score of 2 to 4 was defined as fair healing, and a score of 5 to 6 indicated complete healing. Medical records were also retrospectively reviewed to identify perioperative variables associated with poor early sternal healing.

Results

Three to six months after surgery, the average total score of sternal healing was 2.07±1.52 and 68 patients (34.5%) showed poor healing. Poor healing was most frequently found in the manubrium, which was scored as zero in 72.6% of patients. In multivariate analysis, the factors associated with poor early healing were shorter post-surgery time, older age, diabetes mellitus, and postoperative renal dysfunction. In later CT images, the average sternal healing score improved to 5.88±0.38 and complete healing was observed in 98.2% of patients.

Conclusion

Complete sternal healing takes more than three months after a median sternotomy for CABG using sBITA. Healing is most delayed in the manubrium.

Clinical results of cardiovascular surgery in the patients older than 75 years

BACKGROUND

The balance of the risks and the benefits of cardiac surgery in the elderly remains a major concern. We evaluated the early and mid-term clinical results of patients aged over 75 years who underwent major cardiovascular surgery.

METHODS

Two hundred and fifty-one consecutive patients, who underwent cardiac surgery at Seoul National University Bundang Hospital between July 2003 and June 2011, were included in this study (mean age, 78.7±3.4 years; male:female=130:121). Elective surgery was performed in 112 patients, urgent in 90, and emergency in 49.

RESULTS

Early mortality was 12.7% (32/251). Follow-up completion was 100%, and the mean follow-up duration was 2.8±2.2 years. Late mortality was 24.2% (53/219). There were 283 readmissions in a total of 109 patients after discharge. However, the reason for readmission was related more to non-cardiac factors (71.3%) than to cardiac factors. The overall survival estimates were 79.2% at the 1-year follow-up and 58.4% at the 5-year follow-up. Patients who underwent elective surgery had a lower early mortality rate (elective, 4.5%; urgent, 13.3%; emergency, 30.6%) and better overall survival rate than those that underwent urgent or emergency surgery (p <0.001).

CONCLUSION

The timing of cardiac surgery was found to be an independent risk factor for early and late mortality. Thus, earlier referral and intervention may improve operative results. Further, comprehensive coordinated postoperative care is needed for other comorbid problems in aged patients.

Semiconducting-to-metallic photoconductivity crossover and temperature-dependent Drude weight in graphene

We investigate the transient photoconductivity of graphene at various gate-tuned carrier densities by optical-pump terahertz-probe spectroscopy. We demonstrate that graphene exhibits semiconducting positive photoconductivity near zero carrier density, which crosses over to metallic negative photoconductivity at high carrier density. These observations can be accounted for by the interplay between photoinduced changes of both the Drude weight and carrier scattering rate. Our findings provide a complete picture to explain the opposite photoconductivity behavior reported in (undoped) graphene grown epitaxially and (doped) graphene grown by chemical vapor deposition. Notably, we observe nonmonotonic fluence dependence of the photoconductivity at low carrier density. This behavior reveals the nonmonotonic temperature dependence of the Drude weight in graphene, a unique property of two-dimensional massless Dirac fermions.

Perfusion defects detected after liver transplantation on multidetector computerized tomography: short- and long-term follow-up

BACKGROUND

Perfusion defects are sometimes found during the follow-up computerized tomography (CT) after liver transplantation (OLT). This study sought to determine the short- and long-term outcomes of perfusion defects observed after OLT with the use of multidetector CT.

METHODS

From February 4, 2004, to December 8, 2011, a total 46 LTs were performed in our hospital owing to end-stage liver cirrhosis (n = 43), liver cirrhosis with hepatocellular carcinoma (HCC; n = 1), combined HCC with cholangiocellular carcinoma (CCC; n = 1), or hepatic failure from acute hepatitis A (n = 1). The transplanted livers were procured from cadaveric (n = 24) or living related donors (n = 22). The average age of the recipient was 53.3 ± 10.4 years. The male-female ratio was 30:16. Postoperative multidetector CT was performed with a dynamic sequence in 203 examinations and with a portal phase in 46 examinations. The contrast media was Radisense. The rate of injection of 120 mL was 3 mL/s with a power injector; the iodine concentration was 300 or 370 mg/dL. Follow-up ranged from 3 months 3 days to 7 years 363 days. We classified perfusion defects as chronic segmental or subsegmental benign ischemia, transient focal perfusion defects, benign subcapsular ischemia, or fatal whole liver perfusion defects.

RESULTS

There were 3 cases of chronic segmental or subsegmental benign ischemia, 8 focal transient perfusion defects, 1 benign subcapsular ischemia, and 4 fatal whole liver perfusion defects. Except the fatal cases, all other perfusion defects occurred in the courses of benign conditions without resection or reoperation.

CONCLUSIONS

Most perfusion defects were benign and uneventful, requiring no treatment, with the exception of fatal whole liver perfusion defects, which resulted in death after detection.

Cryoprotection of fibroblasts by carboxylated poly-L-lysine upon repeated freeze/thaw cycles

The cryoprotection of carboxylated h-poly-L-lysine (COOH-PLL) was investigated on fibroblasts [L-929 cells and human dermal fibroblasts (HDFs)] during multiple freeze/thaw cycles. COOH-PLL was not toxic to two fibroblast cell types even at 25% (w/v) concentration, whereas dimethylsulphoxide (DMSO) was highly toxic over 3.13% (v/v). When L-929 cells were subjected to 5 freeze/thaw cycles, the media containing 7.5% (w/v) COOH-PLL maintained cell morphology and significantly suppressed growth inhibition as well as cell detachment (P < 0.05). The result was comparable to the media containing 10% (v/v) DMSO. For HDFs, COOH-PLL could effectively retain cell viability and proliferation against 3 freeze/thaw cycles. Cell viability of HDFs was decreased after 5 freeze/thaw cycles, but COOH-PLL exerted better cryoprotection. The cell type might account for the difference in the observations. The data demonstrated that COOH-PLL is a good cryoprotectant for mammalian cells against repeated freeze/thaw cycles, and may be used for cell preservation in fields of cell transplantation, tissue engineering and regenerative medicine.

Accuracy of CT angiography in the assessment of the circle of Willis: comparison of volume-rendered images and digital subtraction angiography

BACKGROUND

Computed tomography angiography (CTA) is increasingly used for non-invasive imaging of the cerebrovascular diseases.

PURPOSE

To evaluate the accuracy of CTA in the assessment of the variation of the segment calibers of the circle of Willis.

MATERIAL AND METHODS

One hundred and 17 patients with acute SAH (51 men and 66 women, mean age 50.9 years) who underwent CTA using a 16 detector-row CT scanner and DSA were evaluated retrospectively. The CTA and DSA studies were performed within 24 h after the onset of symptoms and within 24 h of each other. A total of 819 arterial segments (A-comA, right and left A1 segment, right and left P-com A, and right and left P1 segment) of the circle of Willis were determined to be aplastic (grade 1), hypoplastic (grade 2), or normal-sized (grade 3) by blinded observers evaluating CTA volume-rendered images. The CTA results were then compared with findings on the corresponding DSA images (reference standard).

RESULTS

The overall agreement between CTA and DSA was 92.4%. We had 62 (7.6%) cases of disagreement (58 cases of under-estimation and four cases of over-estimation by CTA) between tow modalities. The sensitivity and specificity of CTA in the detection of aplastic and normal-sized segments were more than 90%. In contrast, subgroup analysis of the hypoplastic segments showed a sensitivity of 52.6% and a specificity of 98.2%.

CONCLUSION

CTA is highly accurate in the assessment of anatomical variations of the circle of Willis; however, its sensitivity is limited in depicting hypoplastic segments.

Beneficial effects of Undaria pinnatifida ethanol extract on diet-induced-insulin resistance in C57BL/6J mice

This study was performed to evaluate the beneficial effect of Undaria pinnatifida ethanol extract (UEFx) on insulin resistance in diet-induced obese mice. A high-fat diet was supplemented with the UEFx at 0.69% (wt/wt) dose, which contains an equivalent amount of 0.02% fucoxanthin (wt/wt), or with Fx at 0.02% (wt/wt) dose in diet. After 9 weeks, both UEFx supplement significantly lowered the amount of visceral fat, the size of adipocyte, the fasting blood glucose concentration, the plasma insulin and the insulin resistance index similar to pure as shown by Fx supplement, compared to the high-fat (HF) control group. Blood glucose level was negatively correlated with hepatic glucokinase activity (r = -0.533, p < 0.05), whereas positively correlated with hepatic gluconeogenic enzyme activities (r = 0.463, p < 0.05 for glucose-6-phosphatase; r = 0.457, p < 0.05 for phosphoenolpyruvate carboxykinase). Ratio of hepatic glucokinase/glucose-6-phosphatase and glycogen content were significantly elevated by the UEFx and Fx supplements. Supplementation of the UEFx as well as Fx seemed to stimulate the β-oxidation activity and inhibit the phosphatidate phosphohydrolase activity resulting in a decrease in the hepatic lipid droplet accumulation. The results indicate that the UEFx can prevent insulin resistance and hepatic fat accumulation that is partly mediated by modulating the hepatic glucose and lipid homeostasis in the high fat-induced obese mice.

Small atypical cervical nodes detected on sonography in patients with squamous cell carcinoma of the head and neck: probability of metastasis

OBJECTIVE

The purpose of this study was to assess the probability of metastasis of small atypical cervical lymph nodes detected on sonography in patients with squamous cell carcinoma (SCC) of the head and neck.

METHODS

We reviewed, retrospectively and blindly, sonographic findings of 148 patients (118 men and 30 women; mean age, 58.2 years) who underwent curative neck dissection. Each lymph node was classified by using a 4-point scale: 1, definitely benign; 2, indeterminate (small [short-axis diameter <10 mm for levels I and II and <7 mm for levels III-VI] atypical node); 3, definitely metastatic; and 4, large (>3-cm) metastatic. Lymph nodes were considered atypical if they met at least 1 of the following criteria: a long- to short-axis diameter ratio of less than 2.0, absence of a normal echogenic hilum, and heterogeneous echogenicity of the cortex. These results were verified, on a level-by-level basis, with histopathologic findings.

RESULTS

Small atypical nodes were found on sonography in 63 cervical levels of 48 patients, of which 18 (28.6%) were proved to have metastatic nodes. The probability of metastasis was significantly higher with than without a large (>3-cm) ipsilateral metastatic node (0.50 versus 0.20; P = .038) and marginally higher with than without an ipsilateral metastatic node (0.41 versus 0.16; P = .061) but not significantly associated with the T stage of the primary tumor (P = .238) or the presence of an ipsilateral tumor (P = .904).

CONCLUSIONS

Metastasis was encountered in about 30% of small atypical cervical nodes on sonography in patients with SCC of the head and neck. Our results indicate that small atypical nodes must be interpreted with consideration of metastatic nodes in the ipsilateral neck.

Cyclosporin A Has a Protective Effect with Induced Upregulation of Hsp70 and nNOS on Severe Spinal Cord Ischemic Injury in Rabbits

The purpose of this study is to ascertain the neuroprotective effect of cyclosporin A on the 25-min surgical ischemia model in the spinal cords of rabbits with neuropathological correlation and histoimmunochemical analyses measuring HSP70 and neuronal NOS (nNOS). New Zealand white rabbits were randomly divided into four groups (each n = 8): the C2, C7, Cs2, and Cs7 groups. The C2 and C7 groups underwent a 25-min surgical aortic cross-clamp without intervention and were sacrificed respectively on day 2 and on day 7 postoperatively. The Cs2 and Cs7 groups received cyclosporin A (25 mg/kg) intravenously 15 min after the 25-min cross-clamp and were sacrificed respectively on day 2 and day 7 postoperatively. Neurologic functions were evaluated on postoperative days 2 and 7 using the Tarlov scoring system. Then the rabbits were sacrificed for histopathologic observation. HSP 70 and nNOS stains with TUNEL assay were done for the C2 and Cs2 groups. All rabbits survived the experimental procedure. Tarlov's score for the Cs7 group (2.75 +/- 0.89) was significantly higher than that of the C7 group (1.25 +/- 1.39) (p < .05). Tarlov's score of the Cs7 group was also statistically higher on day 7 than on day 2 (p < .05). Strong correlation between the neurological and histological scorings was found. The TUNEL assay showed that the mean number of positive cells in the C2 group was 17.5 +/- 22.6 and in the Cs2 group was 12.5 +/- 11.1, but there was no statistically significant difference between the groups. There was more expression of HSP70 and nNOS in the cyclosporin groups than in the ischemia groups. In conclusion, this study demonstrates that cyclosporin A reduces neurological injury in the rabbit model of 25-min spinal cord ischemia. The neuroprotective effect of cyclosporin A against ischemia seems to be related to overexpressions of nNOS and HSP70.

Distribution and determinants of maximal physical work capacity of Korean male metal workers

The distribution of maximal physical work capacity (MPWC) can be used to establish an upper limit for energy expenditure during work (EEwork). If physically demanding work has wearing effects, there will be a negative relationship between MPWC and workload. This study was conducted to investigate the distribution of MPWC among Korean metal workers and to examine the relationship between workload and MPWC. MPWC was estimated with a bicycle ergometer using a submaximal test. Energy expenditure was estimated by measuring heart rates during work. The study subjects were 507 male employees from several metal industries in Korea. They had a lower absolute VO2max than the Caucasian populations described in previous studies. The older workers had a lower physical capacity and a greater overload at work. A negative relationship was found between MPWC and workload across all age groups. Upper limits for EEwork for all age groups and for older age groups are recommended based on the 5th percentile value of MPWC.

Modeling and experimental verification of plasmas induced by high-power nanosecond laser-aluminum interactions in air

It has been generally believed in literature that in nanosecond laser ablation, the condensed substrate phase contributes mass to the plasma plume through surface evaporation across the sharp interface between the condensed phase and the vapor or plasma phase. However, this will not be true when laser intensity is sufficiently high. In this case, the target temperature can be greater than the critical temperature, so that the sharp interface between the condensed and gaseous phases disappears and is smeared into a macroscopic transition layer. The substrate should contribute mass to the plasma region mainly through hydrodynamic expansion instead of surface evaporation. Based on this physical mechanism, a numerical model has been developed by solving the one-dimensional hydrodynamic equations over the entire physical domain supplemented by wide-range equations of state. It has been found that model predictions have good agreements with experimental measurement for plasma front location, temperature, and electron number density. This has provided further evidence (at least in the indirect sense), besides the above theoretical analysis, that for nanosecond laser metal ablation in air at sufficiently high intensity, the dominant physical mechanism for mass transfer from the condensed phase to the plasma plume is hydrodynamic expansion instead of surface evaporation. The developed and verified numerical model provides useful means for the investigation of nanosecond laser-induced plasma at high intensities.

Pulmonary endometriosis resected by video-assisted thoracoscopic surgery

Catamenial haemoptysis is a rare condition caused by thoracic endometriosis that presents as tracheobronchial or pulmonary endometriosis. The authors report a 31-year-old woman with a 1-year history of catamenial haemoptysis, which was diagnosed by chest CT scan during menses and treated successfully by means of video-assisted thoracoscopic surgery of the solitary pulmonary lesion. There was no evidence of recurrence 6 months after the operation. The authors suggest that video-assisted thoracoscopic surgery is an effective therapy for catamenial haemoptysis caused by localized peripheral pulmonary endometriosis.

Chromosome aberration and lipid peroxidation in chromium-exposed workers

Chromosome aberration frequency and lipid peroxidation levels were analyzed to investigate their efficacy as biological markers for monitoring the genotoxicity and oxidative damage in Korean chromium (Cr)-exposed workers. Fifty-one Cr-exposed workers and 31 age-matched controls in ten chrome-plating plants were sampled. The Cr level was measured in the workers' blood and urine, and in the ambient air at the workplaces. The conventional Giemsa staining method and fluorescence in situ hybridization (FISH) technique were used for chromosome aberration analysis. Spectrum green whole chromosome paint specific for chromosome 4 was used in the FISH procedure. As for lipid peroxidation, malondialdehyde (MDA) was measured in the blood plasma as thiobarbituric acid-reactive substances (TBARS). The blood Cr concentration was statistically correlated with both the frequency of chromatid exchange and the total frequency of chromosome/chromatid breaks and exchanges, as detected by the Giemsa staining. Meanwhile, the frequency of translocation, as detected by the FISH technique, was significantly higher in the Cr-exposed workers than in the controls and it correlated with the blood Cr concentration. Although the concentration of MDA, the metabolite of lipid peroxidation, in the exposed workers was higher than that of the controls, no statistically significant correlation between the MDA level and the blood or urine Cr levels was observed. Accordingly, the genotoxicity and oxidative damage (plasma lipid peroxidation) in the Korean Cr-exposed workers were consequential at quite low exposure levels, plus chromosome rearrangement, especially translocation, was clearly evident as a biological response marker for Cr exposure based on a significant positive correlation between the translocations detected by FISH and the Cr in the blood.

Comparison of myocardial infarction with sequential ligation of the left anterior descending artery and its diagonal branch in dogs and sheep

We report a comparison of the effects of myocardial infarction in dogs and sheep using sequential ligation of the left anterior descending artery (LAD) and its diagonal branch (DA), with hemodynamic, ultrasonographic and pathological evaluations. Five animals were used in each group. After surgical preparation, the LAD was ligated at a point approximately 40% of the distance from the apex to the base of the heart, and after one hour, the DA was ligated at the same level. Hemodynamic and ultrasonographic measurements were performed preligation, 30 minutes after LAD ligation, and 1 hour after DA ligation. As a control, two animals in each group were used for the simultaneous ligation of the LAD and the DA. Two months after the coronary ligation, the animals were evaluated as previously, and killed for postmortem examination of their hearts. All seven animals in the dog group survived the experimental procedures, while in the sheep group only animals with sequential ligation of the LAD and DA survived. Statistically significant decreases in systemic arterial blood pressure and cardiac output, and an increase in the pulmonary artery capillary wedge pressure (PACWP) were observed one hour after sequential ligation of the LAD and its DA in the sheep, while only systemic arterial pressures decreased in the dog. Ultrasonographic analyses demonstrated variable degrees of anteroseptal dyskinesia and akinesia in all sheep, but in no dogs. Data two months after coronary artery ligation showed significant increases in central venous pressure, pulmonary artery pressure, and PACWP in the sheep, but not in the dog. Left ventricular end-diastolic dimension and left ventricular end-systolic dimension in ultrasonographic studies were also increased only in the sheep. Pathologically, the well-demarcated thin-walled transmural anteroseptal infarcts with chamber enlargement were clearly seen in all specimens of sheep, and only-mild-to-moderate chamber enlargements with endocardial fibrosis were observed in the dog hearts. In conclusion, this study confirms that the dog is not a suitable model for myocardial infarction with failure by coronary artery ligation despite negligent operative mortality, when compared directly with an ovine model.

Double-blind naltrexone and placebo comparison study in the treatment of pathological gambling

BACKGROUND

The authors' goal was to assess the efficacy and tolerability of naltrexone in the treatment of pathologic gambling disorder.

METHODS

Eighty-three subjects who met criteria for DSM-IV pathologic gambling disorder were enrolled in a 1-week single-blind placebo lead-in followed by an 11-week double-blind naltrexone or placebo trial. Naltrexone was started at 25 mg/day and titrated upward until maximum symptom improvement or 250 mg/day was achieved. Gambling symptom change was assessed with the patient-rated Clinical Global Impression (PG-CGI-PT), clinician-rated CGI (PG-CGI-MD), and the Gambling Symptom Rating Scale (G-SAS). Side effects were monitored weekly and liver function tests biweekly.

RESULTS

Data from 45 patients were analyzed. Using random regression analysis, significant improvement was noted in all three gambling symptom measures: patient-rated Clinical Global Impression, p <.001; clinician-rated CGI, p <.001; Gambling Symptom Rating Scale, p <.019. At study end, 75% of subjects taking naltrexone were much or very much improved on both the PE-CEI PT and the PG-CGI-MD, compared with only 24% of those on placebo. Elevated liver enzymes occurred in four subjects who were taking analgesics concurrently. Nausea was common during the first week of treatment.

CONCLUSIONS

Results suggest that naltrexone is effective in reducing the symptoms of pathologic gambling. Until further studies corroborate the present findings, our report should be interpreted cautiously.

Variable numbers of TTC repeats in Mycobacterium leprae DNA from leprosy patients and use in strain differentiation

Strain differentiation of Mycobacterium leprae would be of great value for epidemiological investigation to identify the infectious sources of leprosy, to understand transmission patterns, and to distinguish between relapse and reinfection. From the M. leprae genome sequence database, TTC DNA repeats were identified. Primer sets designed to amplify the region flanking TTC repeats revealed PCR products of different sizes, indicating that the number of repeats at each locus may be variable among M. leprae strains. The TTC repeats were not found in Mycobacterium tuberculosis, Mycobacterium avium, Mycobacterium marinum, or human tissues, which indicated their specificity to M. leprae. Sequence analysis of the TTC repeat region in each of the M. leprae strains showed a variation of 10 to 37 repeats. In the M. leprae strains of 34 multibacillary patients at Cebu, Philippines, M. leprae with 24 and 25 TTC repeats was most common, and this was followed by strains with 14, 15, 20, 21, and 28 repeats. This study thus indicates that there are variable numbers of TTC repeats in a noncoding region of M. leprae strains and that the TTC region may be useful for strain differentiation for epidemiological investigations of leprosy.

Reduction of hexavalent chromium collected on PVC filters

Chromium exists at various valences, including elemental, trivalent, and hexavalent chromium, and undergoes reduction-oxidation reactions in the environment. Since hexavalent chromium is known as a human carcinogen, it is most important to evaluate the oxidation-reduction characteristics of the hexavalent chromium species. Although hexavalent chromium can be reduced to trivalent state, the detailed information on this in workplace environments is limited. The purpose of this study was to investigate hexavalent chromium reduction in time in various conditions. A pilot chrome plating operation was prepared and operated in a laboratory for this study. There was evidence that the hexavalent chromium was reduced by time after mist generation. The percentage ratio (with 95% confidence intervals in parentheses) of hexavalent chromium to total chromium was almost 100% (99.1 approximately 102.3) immediately after mist generation, and was reduced to 87.4% (84.8 approximately 89.9) at 1 hour and 81.0% (78.3 approximately 83.5) at 2 hours, respectively. Another test indicated that hexavalent chromium collected on PVC filters was also reduced by time after sampling. Hexavalent chromium was reduced to 90.8% (88.2 approximately 93.3) at 2 hours after sampling. It also was found that hexavalent chromium was reduced during storage in air. It is recommended that air samples of hexavalent chromium be protected against reduction during storage.

The in vitro blood compatibility of poly(ethylene oxide)-grafted polyurethane/polystyrene interpenetrating polymer networks

Poly(ethylene oxide) (PEO)-grafted polyurethane (PU)/polystyrene (PS) interpenetrating polymer networks (IPNs) were synthesized. The effects of the mobile pendant PEO chains with their microphase separated structure on blood-compatibility were investigated. The morphology of both the fracture surface as well as the top surface indicate that the size of the dispersed domains of the PS-rich phase decreased as the grafting with the PEO was increased. The swelling ratio also decreased as the grafting with the PEO was increased. However, the dynamic contact angle and the interfacial energy between IPN surface and water decreased, due to the structural reorganization of the pendant PEO chains. PU/PS IPNs have an excellent mechanical property as compared with PU homopolymers. The adsorption of bovine plasma fibrinogen (BPF) onto the PU/PS IPNs and PU homopolymers was effectively suppressed by the PEO-grafting. In the platelet adhesion test, the amount of platelets adsorbed, activated, and/or coagulated upon the PEO-grafted PU/PS IPNs were reduced when compared to the ungrafted PU homopolymers.

Biochemical, molecular and physiological characterization of a new beta-casein variant detected in Korean cattle

There are seven known genetic variants of bovine beta-casein (beta-CN)--A1, A2, A3, B, C, D and E. In this study, we identified a new genetic variant (named beta-CN H) which migrates slower than the other variants in acidic starch gel electrophoresis. We confirmed through protein and DNA sequence analyses that the H variant differs at five residues from the A2 sequence: Arg25/Cys, Leu88/Ile, Gln117/Glu, Glu175/Gln and Gln195/Glu. Of these substitutions the 25th residue was contained in the casein phosphopeptide (CPP) region. In rats, calcium solubilizing effect of the CPP of bovine variant H was increased by approximately 23% compared with that of the CPP of non-H. Using extensive Korean Bos taurus pedigrees, we confirmed that beta-CN H was controlled by a codominant allele.

Increase in signal intensities on T1-weighted magnetic resonance images in asymptomatic manganese-exposed workers

OBJECTIVES

To clarify the clinical significance of increased signal intensities on T1 weighted magnetic resonance imaging (MRI) we performed a large-scale epidemiological study on asymptomatic manganese (Mn)-exposed workers with its focus on MRI.

METHODS

We randomly selected 121 male workers out of a total of 750 workers including Mn-exposed, non-exposed manual, and non-exposed clerical workers in the factories. We studied environmental and biological monitoring, neurological examination, and MRI.

RESULTS

The proportion of workers with increased signal intensities among the exposed, the non-exposed manual workers, and the non-exposed clerical workers was 46.1%, 18.8%, and 0%, respectively. Especially, 73.5% of the welders showed increased signal intensities. In no subject, were clinical signs of manganism observed. The pallidal index correlated with blood Mn concentration.

CONCLUSION

Increase in signal intensities on the T1-weighted image reflect recent exposure to Mn, but not necessarily manganism. At which increase of signal intensity, the progression of manganism from Mn exposure occurs, remains to be solved.

Idiopathic parkinsonism with superimposed manganese exposure: utility of positron emission tomography

It is difficult to distinguish manganism from idiopathic parkinsonism by clinical signs only. Case history and examination: A 48-year-old welder for over 10 years complained of masked face, right side (arm and leg) resting tremor, and bradykinesia for over one year. Magnetic resonance imaging (MRI) findings showed symmetrical high signal intensities in the globus pallidus on T1 weighted image. These intensities disappeared almost completely six months after cessation of exposure. 18F-6-fluorodopa (18F-dopa) positron emission tomography (PET) findings showed reduced 18F-dopa uptake in the left putamen, findings which appear in idiopathic parkinsonism. A PET study is necessary to distinguish manganism from idiopathic parkinsonism, especially in a working environment with elevated Mn concentrations, such as welding.

Biological control of fusarium wilt of cucumber by chitinolytic bacteria

ABSTRACT Two chitinolytic bacterial strains, Paenibacillus sp. 300 and Streptomyces sp. 385, suppressed Fusarium wilt of cucumber (Cucumis sativus) caused by Fusarium oxysporum f. sp. cucumerinum in nonsterile, soilless potting medium. A mixture of the two strains in a ratio of 1:1 or 4:1 gave significantly (P < 0.05) better control of the disease than each of the strains used individually or than mixtures in other ratios. Several formulations were tested, and a zeolite-based, chitosan-amended formulation (ZAC) provided the best protection against the disease. Dose-response studies indicated that the threshold dose of 6 g of formulation per kilogram of potting medium was required for significant (P < 0.001) suppression of the disease. This dose was optimum for maintaining high rhizosphere population densities of chitinolytic bacteria (log 8.1 to log 9.3 CFU/g dry weight of potting medium), which were required for the control of Fusarium wilt. The ZAC formulation was suppressive when added to pathogen-infested medium 15 days before planting cucumber seeds. The formulation also provided good control when stored for 6 months at room temperature or at 4 degrees C. Chitinase and beta-1,3-glucanase enzymes were produced when the strains were grown in the presence of colloidal chitin as the sole carbon source. Partial purification of the chitinases, followed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and activity staining, revealed the presence of five bands with molecular masses of 65, 62, 59, 55, and 52 kDa in the case of Paenibacillus sp. 300; and three bands with molecular masses of 52, 38, and 33 kDa in the case of Streptomyces sp. 385. Incubation of cell walls of F. oxysporum f. sp. cucumerinum with partially purified enzyme fractions led to the release of N-acetyl-D-glucosamine (NAGA). NAGA content was considerably greater when pooled enzyme fractions (64 to 67) from Paenibacillus sp. were used, because they contained high beta-1,3-glucanase activity in addition to chitinase activity. Suppression of Fusarium wilt of cucumber by a combination of these two bacteria may involve the action of these hydrolytic enzymes.

Streptokinase secretion by Serratia marcescens signaled by the C-terminal 41 amino acid segment of metalloprotease

In order to investigate the secretion signal of Serratia marcescens metalloprotease (SMP) and examine the ability of the secretion signal to secrete foreign proteins, hybrid genes encoding the passenger-SMP C-terminal segments were constructed. As a passenger protein, streptokinase (SK) deprived of its signal peptide was used. Three kinds of SMP C-terminal segments containing 41, 80, or 220 amino acid residues were fused to the C-terminus of SK as secretion signals. The SK-SMP chimeric proteins containing 41 or 220 amino acid segments of the SMP C-terminus were secreted into the culture medium by the SMP transporter of S. marcescens. This result suggests that cytoplasmic SK is secreted into the external medium by the C-terminal segments of SMP and also shows that the smallest, 41 amino acid segment of the SMP C-terminus functions as a secretion signal of foreign proteins as well as SMP.

Nucleotide sequence of nucleocapsid protein (N) of Hantaan virus isolated from a Korean hemorrhagic fever patient

The nucleotide sequence of the nucleocapsid protein (N) coding region of a Hantaan virus strain (CFC94-2) isolated from a Korean Hemorrhagic Fever (KHF) patient was determined by sequencing a series of deletion mutants. Comparison of the N coding sequence of CFC94-2 to the sequence of the prototype of Hantaan virus, strain 76-118 reveals a 4.97% difference in the nucleotide sequence and a 1.6% difference in the deduced amino acid sequence. The rate of amino acid sequence variation in N protein of different Hantaan viruses (1.6%) is quite similar to that in G1 and G2 envelope proteins (1.7%). These results suggest that N protein may be under a similar selection pressure to G1 and G2 envelope proteins against host immune system.

The Leu-3 residue of Serratia marcescens metalloprotease inhibitor is important in inhibitory activity and binding with Serratia marcescens metalloprotease

Serratia marcescens metalloprotease inhibitor (SmaPI) is a proteinase inhibitor toward Serratia marcescens metalloprotease (SMP). In sequential deletion analysis of the N-terminal region of the SmaPI, SmaPIs starting at Ser-2 and Leu-3 residues, respectively, had nearly a full inhibitory activity toward SMP. However, SmaPI starting at Ala-4 residue showed severely decreased inhibitory activity. Furthermore, kinetic analysis demonstrated that SmaPI starting at the Ala-4 residue had an inhibition constant for SMP approximately fourfold higher than that of wild-type SmaPI. The interactions of Leu-3 with SMP contribute 0.73 kcal mol-1 to the overall stability of the SMP-SmaPI complex (8.44 kcal mol-1). To elucidate the detailed role of the Leu-3 residue in inhibitory activity of SmaPI, several site-directed mutations were introduced. The inhibitory activities of Leu-3 mutants in which the Leu-3 has been converted to Ala, Asp, Gly, Ile, Lys, Phe, or Pro were correlated with the hydrophobicities of substituted amino acids. About 0.3 kcal mol-1 is attributable to the side chain of the Leu-3 residue in the binding with SMP. From these results, it is suggested that (i) in contrast with the Erwinia chrysanthemi inhibitor, Gly-1 and Ser-2 of SmaPI are not critical and (ii) the hydrophobicity of Leu-3 may be important in its inhibitory activity and binding with SMP.

Revaluation on the types and pattern of distribution of sinusoidal fenestrations in the lobule of normal rat liver

BACKGROUND

There is a need to identify the existence of large fenestrations and to evaluate the type and pattern of the distribution of sinusoidal fenestrations in the hepatic lobule.

METHODS

The sinusoidal fenestrations in the rat liver lobule were investigated by scanning electron microscopy of perfusion-fixed specimens and by transmission electron microscopy of freeze-fracture replicas from immersion-fixed specimens. Ringer solution used for precleaning was equilibrated with 84%/16% O2/CO2 at 37 degrees C, and the perfusion pressure was maintained at 5-10 mmHg in the portal vein.

RESULTS

The fenestrations were recognized on the luminal surface of sinusoids on the basis of regional difference in size and distribution within the lobule and divided into three types: small, medium-sized, and large. The small fenestrations were numerous in each region. The number of medium-sized fenestrations was large in the pericentral and intermediate regions, while that of large fenestrations was predominant in the intermediate region. Based on the occurrence of fenestrations, the sinusoids were also divided into three types. The type I sinusoid mainly showed small fenestrations and was predominant in the periportal region. The type II sinusoid showed small and medium-sized fenestrations and was predominant in the pericentral region. The type III sinusoid showed all the types of fenestrations including large ones and was predominant in the intermediate region. The images showing dumbbell-shaped or irregularly shaped margins were observed between small or medium-sized fenestrations on the freeze-fracture replica.

CONCLUSIONS

1) The fenestrations are divided into three types according to the size and pattern of distribution within the lobule. 2) The sinusoids are also divided into three types based on the distribution pattern of each type of fenestrations. 3) The small fenestrations are evenly distributed throughout the entire lobule, while the medium-sized and large fenestrations show the regional difference within the lobule. 4) The large fenestrations exist as real structures of the endothelial lining cells of sinusoids and may result from the fusion of contiguous smaller ones.

Characterization of a metalloprotease inhibitor protein (SmaPI) of Serratia marcescens

As suggested by Y. Suh and M.J. Benedik (J. Bacteriol. 174: 2361-2366, 1992), Serratia marcescens ATCC 27117 produced very small amounts (0.8 U ml-1) of an inhibitor protein (SmaPI) that shows an inhibitory activity against extracellular 50-kDa metalloprotease (SMP) of S. marcescens and that is localized in the periplasm of cells at the optimal growth temperature of 25 degrees C. A recombinant S. marcescens harboring plasmid pSP2 encoding SMP and SmaPI genes produced 20 U of SmaPI ml-1 that is also localized in the periplasm of cells at 25 degrees C. However, a large amount of SmaPI (86 Uml-1) was extracellularly produced at the supraoptimal growth temperature 37 degrees C from the recombinant S. marcescens (pSP2). We purified SmaPI from the culture supernatant of S. marcescens (pSP2) grown at 37 degrees C, and some biochemical properties were characterized. SmaPI had a pI value of about 10.0 and was a monomeric protein with a molecular mass of 10,000. SmaPI was produced from a precursor SmaPI by cleavage of a signal peptide (26 amino acid residues). The inhibitor was stable in boiling water for up to 30 min. The thermostability of SmaPI can be attributed to its reversible denaturation. SmaPI inhibited SMP by formation of a noncovalent complex with a molar ratio of 1:1 and showed a high protease specificity, which inhibited only SMP among the various proteases we examined.

Purification and Characterization of a Maltotetraose-Forming Alkaline (alpha)-Amylase from an Alkalophilic Bacillus Strain, GM8901

An alkalophilic bacterium, Bacillus sp. strain GM8901, grown at pH 10.5 and 50(deg)C, produced five alkaline amylases in culture broth. At an early stage of the bacterial growth, amylase I (Amyl I) was produced initially and then, as cultivation progressed, four alkaline amylases, Amyl II, Amyl III, Amyl IV, and Amyl V, were produced from proteolytic degradation of Amyl I. A serine protease present in the culture medium was believed to be involved in Amyl I degradation. We purified Amyl I from the culture supernatant by ammonium sulfate precipitation, heparin-Sepharose CL-6B column chromatography, phenyl-Toyopearl column chromatography, and Mono Q HR5/5 high-performance liquid chromatography. The molecular weight of Amyl I was estimated to be about 97,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Amyl I had an extremely high optimal pH of 11.0 to 12.0 and was stable in a broad pH range of 6.0 to 13.0. Amyl I had an optimal temperature of 60(deg)C and was stable up to 50(deg)C. Thermostability was increased in the presence of Ca(sup2+) and soluble starch. The enzyme required metal ions such as Ca(sup2+), Mg(sup2+), Cu(sup2+), Co(sup2+), Ag(sup+), Zn(sup2+), and Fe(sup2+) for its enzyme activity and was inhibited by 1 mM EDTA and 1 mM phenylmethylsulfonyl fluoride. According to the mode of action of Amyl I on starch, Amyl I was classified as an (alpha)- and exo-amylase. Amyl I produced maltotetraose predominantly from starch via intermediates such as maltohexaose and maltopentaose.

Antithrombogenicity of hydrophilic polyurethane-hydrophobic polystyrene IPNs. I. Synthesis and characterization

A series of interpenetrating polymer networks (IPNs) composed of hydrophilic polyurethane (PU) and hydrophobic polystyrene (PS) were prepared by the simultaneous polymerization method. The PU network was synthesized via the isocyanate-terminated PU prepolymer based on polyethylene glycol (PEG), a highly hydrophilic oligomer, and hexamethylene diisocyanate (HDI). The bulk and surface characteristics of these materials were analyzed by differential scanning calorimetry (DSC), tensile testing, scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared (ATR-FTIR), electron spectroscopy for chemical analysis (ESCA), and contact angle measurement. The PU/PS IPNs prepared in this study exhibited phase separated structures, which had dispersed PS domains in the continuous PU matrix, in both the bulk and surface showing two transition temperatures. The IPN containing 50 wt% of PS showed good mechanical properties. The enrichment of PU phase in the surface was revealed by SEM, ATR-FTIR, ESCA, and contact angle measurement.

Antithrombogenicity of hydrophilic polyurethane-hydrophobic polystyrene IPNs. II. In vitro and ex vivo studies

To investigate the effect of hydrophilic and hydrophobic surfaces with phase separated structure on their blood responses, interpenetrating polymer networks (IPNs) composed of hydrophilic polyurethane (PU) and hydrophobic polystyrene (PS) were prepared by simultaneous polymerization. In vitro protein adsorption, in vitro platelet adhesion, and ex vivo A-A shunt test were carried out to evaluate the blood compatibility of the PU/PS IPNs. The results of protein adsorption on the PU/PS IPN surfaces indicated that albumin preferentially adsorbed on the hydrophilic surface (PU), while fibrinogen preferentially adsorbed on the hydrophobic surface (PS). The PU/PS IPNs exhibited suppressive properties for both platelet adhesion and activation. The occlusion time of U50S50 IPN containing 50 wt% of PS was twice as long as that of the PU control (50 min), indicating enhanced blood compatibility, presumably due to the selective adsorption of plasma proteins and the suppression of the adhesion and activation of platelets.

Surface roughness evaluation via ultrasonic scanning

Despite extensive applications of ultrasonic waves to various nondestructive testing and evaluation of materials, scattering of focused ultrasonic waves due to surface roughness has not been fully investigated. This paper presents an analytical and experimental evaluation of surface roughness measurement using focused ultrasonic beams. The characteristics of focused ultrasonic waves are analyzed by using the impulse response method with a sine-modulated Gaussian pulse as source. First, the beam profile in the focal plane of the focused ultrasonic transducer is analyzed both numerically and experimentally. Second, peak amplitude distribution and reflected waveforms from a flat surface with various incident angles are analytically generated and compared with experimental results. Then, the peak amplitudes of the ultrasonic waves reflected from cusped surfaces which are easily found among machined surfaces are analyzed and compared with experimental data for the first time. The analysis shows good agreement between analytical and experimental results. The excellent correlation between the measurements using a profilometer and the proposed ultrasonic system demonstrates a good potential for surface roughness measurement by ultrasonic sensing.

Some observations on the morphological evidence for mechanism of the bile secretion

The morphological evidence of the intracellular route of bile secretion was investigated in the liver of goldfish (Carassius auratus) as revealed by electron microscopy. Smooth surfaced tubules or cisterns within or adjacent to the Golgi apparatus showed linear saccular forms and contained sparse particulate or cloudy materials of low electron density. The isolated vacuoles were restrictedly found between the Golgi apparatus and the intracellular bile canaliculus or hepatocytic side at the zone of transition. These vacuoles showed no reaction for acid phosphatase activity, and contained only a few cloudy materials similar to those found in the saccular tubules and within the bile canaliculus. Some of these vacuoles fused with the luminal cytolemmas of the bile canaliculus. Bases on these findings, it was assumed that these vacuoles are structures participating in transport and secretion of bile constituents and derive from the linearly sacculated tubules or cisterns in the Golgi zone. Duct cells showed no morphological evidence to suggest bile secretion.