Self-Assembled Silica Nanostructures: Simultaneous Discrimination of Handedness, Pitch and Diameter of Helical Silica Nanotubes.

The left- and right-handed helical silica nanostructures were obtained with the aid of organic templates, the formation of the nanostructures might follow a co-operation self-assembly mechanism. The chirality of the organogel self-assemblies was successfully transcribed in to the silica. The helical pitch and pore size of the silica nanotubes sensitively depended on the optical purity of the neutral gelator in the reaction mixtures.

Skeletal myoblast transplantation for attenuation of hyperglycaemia, hyperinsulinaemia and glucose intolerance in a mouse model of type 2 diabetes mellitus.

AIMS/HYPOTHESIS: We aimed to demonstrate the feasibility and efficacy of intra-muscular transplantation of human skeletal myoblasts (hSkMs) for attenuation of hyperglycaemia and improvement of insulin sensitivity using a mouse model of type 2 diabetes mellitus. METHODS: KK Cg-Ay/J mice, aged 12 to 14 weeks, underwent an initial intraperitoneal glucose tolerance test (GTT) and were divided into the following groups: KK control group, basal medium (M199) only; KK myoblast group, with hSkM transplantation; KK fibroblast group, with human fibroblast transplantation. Non-diabetic C57BL mice were used as an additional normal control and also had hSkM transplantation. Cells were transplanted intra-muscularly into the skeletal muscles of the mice. All animals were treated with ciclosporin for 6 weeks only. HbA(1c) and fasting GTT, as well as serum adiponectin, cholesterol, insulin and triacylglycerol were studied. RESULTS: Immunohistochemistry studies showed extensive survival of the transplanted hSkMs in the skeletal muscles at 12 weeks, with nuclei of the hSkMs integrated into the host muscle fibres. Repeat GTT showed a significant decrease in glucose concentrations in the KK myoblast group compared with the KK control and KK fibroblast groups. The KK myoblast group also had reduced mean HbA(1c), cholesterol, insulin and triacylglycerol, and increased adiponectin compared with the KK control and KK fibroblast groups. C57BL mice showed no change in glucose homeostasis after hSkM transplant. CONCLUSIONS/INTERPRETATION: Human skeletal myoblast transplantation attenuated hyperglycaemia and hyperinsulinaemia and improved glucose tolerance in the KK mouse. This novel approach of improving muscle insulin resistance may be a potential alternative treatment for type 2 diabetes mellitus.

Off-pump coronary artery bypass grafting is a safe and effective treatment modality for Asian patients requiring coronary revascularisation.

INTRODUCTION: Off-pump coronary artery bypass grafting (OPCABG) is gaining widespread acceptance as the preferred choice for myocardial revascularisation. However, no definite data exist as to whether it is better than conventional CABG. We aimed to study the efficacy of the procedure in our patients, which constituted of a predominantly Asian population. METHODS: Between January 2000 and December 2002, 1062 patients underwent isolated coronary artery bypass in our institution. 184 patients (17.3 percent) underwent OPCABG. Patients were preoperatively prospectively risk stratified under the EuroSCORE risk assessment model under high, medium and low risk classes thereby making them comparable. Post-operative complications, intensive care unit stay, hospital stay, types of grafts done were then analysed in these different risk classes. RESULTS: The incidence of off-pump procedures showed a gradual increase over the last three years in this institution. A reduction in the number of post-operative complications, hospital stay, intensive care unit stay and mortality in the off-pump group was observed. Certain differences were found to be statistically significant. CONCLUSION: Off-pump CABG is a safe and viable alternative to conventional CABG as a treatment modality for surgical coronary revascularisation.

Deep hypothermic circulatory arrest in adults undergoing aortic surgery: local experience.

INTRODUCTION: The aim of our study was to evaluate the efficacy and safety of deep hypothermic circulatory arrest (DHCA) as a method of cerebral protection during aortic surgery. MATERIALS AND METHODS: We carried out a retrospective review of 59 consecutive patients (48 men, 11 women) undergoing elective or emergency aortic surgery requiring DHCA from January 1999 to April 2002 in 2 tertiary care hospitals. Data regarding demographics, clinical characteristics, operation type, duration of circulatory arrest, nasopharyngeal temperatures, use of retrograde cerebral perfusion and central nervous system (CNS) morbidity and perioperative mortality were collected and analysed. RESULTS: There were 47 (79.7 %) operations for aortic dissections and 12 (20.3 %) for aortic aneurysms. The mean duration of circulatory arrest was 42 +/- 23 minutes. The lowest nasopharyngeal temperature at the time of arrest was 16.5 degrees +/- 1.9 degrees C. Eight (13.6 %) patients had a new irreversible neurologic deficit postoperatively. These patients had a mean circulatory arrest time of 50 +/- 28 minutes. Temporary neurologic dysfunction occurred in 8 (13.6 %) patients. Intra-hospital mortality was 22 %. The mean circulatory arrest time for patients who died was 54 +/- 24 minutes. CONCLUSION: DHCA is a simple and effective method of CNS protection in aortic surgery with satisfactory outcomes. With increased surgical and anaesthetic experience, as well as selective use of adjuncts of cerebral protection, reductions in mortality and neurological morbidity will likely be achieved in the future.

Effectiveness of transient immunosuppression using cyclosporine for xenomyoblast transplantation for cardiac repair.

We studied the survival of human myoblast for cellular myocardial reconstruction in a porcine model of chronic myocardial ischemia with immune tolerance using transient immunosuppression. A porcine model of chronic cardiac ischemia was created in 10 pigs (DMEM medium-injected n = 4; myoblast transplanted n = 6) by clamping ameroid ring around left circumflex coronary artery. Three weeks later, 3 x 10(8) human myoblasts carrying lac-z reporter gene were transplanted in multiple sites (0.25 mL each) into the left ventricular wall. Immunosuppression was achieved with 5 mg/kg cyclosporine for 6 weeks after cell transplantation. After animals were euthanized between 6 and 30 weeks after cell transplantation; the heart was removed for histological studies. Discontinuation of immunosuppression after 6 weeks of cell transplantation did not result in donor cell rejection. The lac-z-positive donor cells were detected in porcine host cardiac tissue for up to 30 weeks posttransplantation, expressing human skeletal myosin heavy chain. The results highlight the effectiveness of transient immunosuppression for myoblast transplantation for cardiac repair.

Computational modelling of blood flow through curved stenosed arteries.

A computational model of three-dimensional blood flow in curved arteries with elliptic stenosis was developed. Two groups of models, (a) different angles of curvature and (b) degrees of stenosis, have been studied under typical conditions for stenosed coronary artery. Useful information on the haemodynamics has been obtained. Results of pressure drop show that the presence of the curvature augments the increased flow resistance due to stenotic lesions. The study also demonstrates the significant presence of secondary flow in a curved artery. In addition, the results have shown that the secondary flow in a curved artery brings about elevated shear stress on the vessel wall. These results indicated that both curvature and stenosis should be considered together by cardiologists to assess or quantify the severity of the stenosis. This study employed a powerful computer-aided design (CAD) package to construct the model and a commercial computational fluid dynamics (CFD) code for the analysis of blood flow in stenosed arteries. The long-term application of this form of research promises to be an effective tool for gaining insights into the pathology of arterial diseases.

A case report on the perinatal management of a 30-week preterm baby with congenital complete heart block.

INTRODUCTION: Congenital complete heart block is an uncommon condition in the newborn, but is known to occur with maternal systemic lupus erythematosus. CLINICAL PICTURE: This paper presents one such baby with complete heart block who was born premature (after a gestation of 30 weeks) and weighing 759 g. TREATMENT: Continuous isoprnaline infusion was initially used to support the baby while her other neonatal problems were treated. A Medtronics VV1 pacemaker was subsequently inserted to maintain a heart rate that would be more physiologically acceptable for the patient. OUTCOME: This baby is currently thriving well, having been followed up for one year. CONCLUSIONS: The management issues, encompassing maternal and neonatal problems, and a review of current literature on this condition are discussed.

Needlescopic thoracic sympathectomy: treatment for palmar hyperhidrosis.

BACKGROUND: Open thoracic sympathectomy has been the established option for patients with essential hyperhidrosis. Recently, video-assisted endoscopic sympathectomy has provided a simple, safe, reliable, and cost-effective alternative to the earlier technique. With advances in instrumentation, performing the procedure through 2-mm and 3-mm needlescopic ports is now possible. The authors evaluate the effectiveness of so-called needlescopic thoracic sympathectomy for the treatment of primary hyperhidrosis. METHODS: Thirty five consecutive patients with a mean age of 24 years, including 23 men and 12 women, underwent bilateral needlescopic thoracic sympathectomies at the National University Hospital of Singapore. RESULTS: The mean operative duration was 56 minutes, and the mean hospital stay was 1.2 days. In no patient did Horner's syndrome or significant pneumothorax develop. The rate of success, defined as completely dry hands, was 97%. Two patients had unilateral recurrences that responded well to repeat needlescopic sympathectomies. We performed a total of 72 sympathectomies. CONCLUSIONS: Our study demonstrates that the use of miniature port access sites produces excellent medical and cosmetic results and is associated with a short hospital stay and low risk of complications.

Hybrid cardiac revascularisation surgery.

Currently, 3 methods of myocardial revascularisation are available for the treatment of coronary artery disease: i) coronary artery bypass grafting (CABG); ii) percutaneous transluminal coronary angiography (PTCA), and iii) transmyocardial laser revascularisation (TMR). Until recently, these procedures were performed exclusive to one another. We report 2 cases of minimally invasive direct coronary artery bypass grafting with subsequent PTCA, and 1 case of staged PTCA followed by TMR performed at our institution. We discuss the role of hybrid procedures in the current era of treatment of ischaemic heart disease.

Influence of surgery on aortic valve prolapse and aortic regurgitation in doubly committed subarterial ventricular septal defect.

Doubly committed subarterial ventricular septal defects should be closed surgically once aortic valve deformity is present before the onset of aortic regurgitation.

Enzymatic dissolution of post-operative haemothorax by purified streptokinase.

Enzymatic dissolution of haemothorax is highly effective in the evacuation of proteinaceous material from the pleural space. Its use in postcardiotomy haemothorax has not been described. We report the case of a 4-year-old girl with Fallot's Tetralogy diagnosed at birth. She underwent a total correction of Fallot's Tetralogy at 4 years of age. Chest X-ray taken post-operatively showed a large pleural collection in her right haemithorax. Repeated intraplueral infusion of purified streptokinase into the right upper pleural chest tube greatly reduced the extent of the right haemothorax. Enzymatic dissolution of haemothorax by purified streptokinase has proven to be a rapid and successful method of therapy. It has provided an alternative which is less invasive and has a low morbidity.

Bidirectional cavopulmonary anastomosis.

The Fontan operation has been used to palliate patients with a functional single ventricle. In many such patients the operative risk for a Fontan procedure is high. The bidirectional cavopulmonary anastomosis (BCPA) is a useful intermediate palliative procedure before Fontan correction. It may reduce the deleterious sequelae of chronic hypoxaemia and long-term ventricular overload, thus yielding a more suitable Fontan candidate. We reviewed our experience of 9 patients with univentricular hearts who were at the time of the BCPA not considered suitable candidates for conventional Fontan operation. Two patients had double inlet right ventricle (DIRV) with pulmonary stenosis (PS) and ventricular septal defect (VSD), 2 had univentricular heart, 4 had tricuspid atresia (TA) and hypoplastic right ventricle (RV), 1 patient had atrioventricular septal defect (AVSD) with double outlet right ventricle (DORV) with hypoplastic RV. Two of the 9 patients had bilateral superior vena cavae. All except one had undergone prior palliative operations. The mean age at BCPA was 4.7 years (range 1.5 years to 6 years) and the mean weight at surgery was 15 kg (range 7 to 22 kg). There were no operative deaths. The mean hospitalization stay was 8.5 days (range 5 to 13 days) with a mean follow up of 14 months. Median oxygen saturation improved from 78.7 +/- 6.3% to 85.9 +/- 3.9%. The BCPA is a useful palliative procedure to stage Fontan type reconstruction in selected patients with univentricular hearts.

Treatment of delayed partial bronchial rupture with expandable metallic stent.

Traumatic bronchial rupture is a rare entity. The severity of the trauma often causes lethal injury to other thoracic organs. The incidence in patients with blunt chest trauma admitted to the hospital ranges from 1.5% to 3%. As a rule, early diagnosis and surgical treatment are important to facilitate successful repair of the disruption. We describe an unusual case of bronchial rupture which was diagnosed 15 days after blunt chest trauma and was treated by bronchial stenting. The success of this case involving the left main bronchial rupture provides a feasible alternative to the repair of partial airway disruption and greatly reduces the morbidity.

Minimally invasive surgical closure of atrial septal defects via a right anterior thoracotomy.

BACKGROUND: Surgical closure of the atrial septal defect (ASD) is a low-risk operation with little post-operative morbidity involved. The standard approach to ASD closure is via a median sternotomy. However the post-operative midline scar is cosmetically undesirable. PATIENTS: We report our experience with four female patients who have undergone closure of ASD through a right anterior thoracotomy and a left groin incision for femoral cannulation. RESULTS: Post-operative recovery was uneventful. The cosmetic results of their operations were good. CONCLUSION: Closure of ASD via a right anterior approach is a safe method and should preferably be used in young female patients, as better cosmetic results are expected.

Minimally invasive direct coronary artery bypass.

BACKGROUND: Minimally invasive cardiac surgery is a new and promising approach to the treatment of coronary artery disease allowing surgery to be performed through smaller incisions with lesser morbidity. METHODOLOGY: From November 1995 to February 1997, ten minimally invasive direct coronary artery bypass (MIDCAB) grafts were performed. The left internal mammary artery was used to bypass the left anterior descending coronary artery (LAD) through a limited left anterior thoracotomy. PATIENTS: There were seven males and three females and their ages ranged from 42 to 72 years (mean = 60 years). Two patients had prior interventional procedures. Cardiopulmonary bypass was used in the first two patients. Two patients were converted to conventional surgery early in the series. RESULTS: There was no mortality nor major morbidity. Mean post-operative hospital stay was seven days. To date, three patients have had post-operative angiography confirming the patency of the left internal mammary artery to LAD anastomosis. CONCLUSION: Early results of the MIDCAB procedure are encouraging. However, the definitive place of such procedures awaits longer term follow-up.

Co-existing left atrial thrombus and myxoma in mitral stenosis--a diagnostic challenge.

We report an unusual case of an adult who underwent a mitral valve replacement with concomitant excision of the left atrial myxoma and thrombus. Echocardiography showed the presence of a large "thrombus" within the left atrial appendage, body and atrial septum. There was difficulty in trying to distinguish between the atrial thrombus and myxoma due to their morphological similarities. At time of surgery, frozen section confirmed the atrial septal component of the thrombus to be an atrial myxoma and the atrial septum was excised to obtain a clear margin.

Outcome of surgical closure of doubly committed subarterial ventricular septal defect.

BACKGROUND: From 1986 to March 1997, 128 patients diagnosed to have doubly committed subarterial ventricular septal defects (VSD) were reviewed. Patients with aortic regurgitation (AR), and aortic valve (AV) deformity or a large left-to-right shunt across the VSD were offered operation. Forty-five patients (27 men, 18 women) agreed to surgical closure of their VSDs. METHODS: Thirty-eight patients had VSD closure alone, and 7 had an additional AV repair. Other associated defects corrected at operation were closure of atrial septal defects, closure of other ventricular septal defects, ligation of patent ductus arteriosus, and repair of ruptured sinus Valsalva aneurysm. RESULTS: There was no mortality nor major morbidity associated with operation. In the 26 patients with AR and AV deformity preoperatively, valve repair was performed in 6 patients. The condition of AR improved in 4, and remained unchanged in 22 patients. In the 10 patients with a deformity of the AV and no AR preoperatively, the condition remained unchanged in 5 patients, from whom 1 had valve operation, but progressed in 5 patients postoperatively at a mean follow-up of 6.4 years. In 9 patients with no deformity of the AV and no AR preoperatively, there was no postoperative AR and no progress of valve deformity. CONCLUSIONS: Excellent results were obtained with VSD closure and AV repair. Surgical closure of VSD, if performed before the onset of AV deformity, may prevent progressive AR. If AV repair is performed after the onset of AV deformity, progressive AR may not always be prevented.