Heat Sink Effect on Tumor Ablation Characteristics as Observed in Monopolar Radiofrequency,Bipolar Radiofrequency,and Microwave,Using Ex Vivo Calf Liver Model

Thermal ablation of liver tumors near large blood vessels is affected by the cooling effect of blood flow, leading to incomplete ablation. Hence, we conducted a comparative investigation of heat sink effect in monopolar (MP) and bipolar (BP) radiofrequency ablation (RFA), and microwave (MW) ablation devices.With a perfused calf liver, the ablative performances (volume, mass, density, dimensions), with and without heat sink, were measured. Heat sink was present when the ablative tip of the probes were 8.0 mm close to a major hepatic vein and absent when >30 mm away. Temperatures (T1 and T2) on either side of the hepatic vein near the tip of the probes, heating probe temperature (T3), outlet perfusate temperature (T4), and ablation time were monitored.With or without heat sink, BP radiofrequency ablated a larger volume and mass, compared with MP RFA or MW ablation, with latter device producing the highest density of tissue ablated. MW ablation produced an ellipsoidal shape while radiofrequency devices produced spheres.Percentage heat sink effect in Bipolar radiofrequency : Mono-polar radiofrequency : Microwave was (Volume) 33:41:22; (mass) 23:56:34; (density) 9.0:26:18; and (relative elipscity) 5.8:12.9:1.3, indicating that BP and MW devices were less affected.Percentage heat sink effect on time (minutes) to reach maximum temperature (W) = 13.28:9.2:29.8; time at maximum temperature (X) is 87:66:16.66; temperature difference (Y) between the thermal probes (T3) and the temperature (T1 + T2)/2 on either side of the hepatic vessel was 100:87:20; and temperature difference between the (T1 + T2)/2 and temperature of outlet circulating solution (T4), Z was 20.33:30.23:37.5.MW and BP radiofrequencies were less affected by heat sink while MP RFA was the most affected. With a single ablation, BP radiofrequency ablated a larger volume and mass regardless of heat sink.     

The Relationship between College Graduate’s Dual Self-Consciousness and Job Search Clarity: The Mediating Role of Perceived Stress

The aim of the study was to explore the relationship between college graduates’ dual self-consciousness, job search clarity and perceived stress, and reveal the mediating role of perceived stress between dual self-consciousness and job search clarity. In this study, 467 college graduates were investigated using the Dual Self-Consciousness Scale, Job Search Clarity Scale, and Perceived Stress Scale. After controlling for gender, age, and region, the results revealed that: (1) private self-consciousness has a significant positive predictive effect on job search clarity; (2) perceived stress has a significant negative predictive effect on job search clarity; (3) perceived stress plays partial mediation effects between private self-consciousness and job search clarity; (4) perceived stress plays complete mediation effects between public self-consciousness and job search clarity; (5) perceived stress has suppressing effects between public self-consciousness and job search clarity.     

A noninvasive, in vivo model for studying strain adaptive bone modeling

We present a noninvasive, in vivo model for strain application in the tibiae of rats. The hind limb of each animal was placed into a device that applied four point bending to the tibia. Bending was applied in the medial-lateral direction causing compression on the lateral surface of the tibia and tension on the anteromedial surface. The peak strain magnitudes were estimated to be between 1600 and 3500 mu strain. In this pilot work, data were collected from 12 rats. The rats received either one cycle per day, four cycles per day, 12 cycles per day, 36 cycles per day, or 108 cycles per day of bending. The experimental (right) tibiae from all of the rats showed new bone formation after 12 days. The control (left) tibiae showed no new bone formation over this period. A better organized, dense bony reaction occurred in regions of lesser strains than in regions of higher strains, where there was a large accumulation of bone easily identified as woven. The organization and density of the newly formed bone appeared to be inversely related to the peak strains in the region. After 40 days of daily loading, the new bone area appeared to be more compact and better mineralized. However, bone formation was still occurring after 40 days. The results of this study suggest that woven bone formation occurred due to the bending stimulus and not due to pathology.     

Validity of the 'Ten Questions' for screening serious childhood disability: results from urban Bangladesh

A survey of 2576 children aged two to nine years was carried out in Dhaka, Bangladesh, as part of a collaborative study to test the validity of a questionnaire (the Ten Questions) for screening severe childhood disabilities in community settings. Approximately 7% of the children were positive on the screen and this rate was slightly higher in boys than girls. The sensitivity, specificity and negative predictive value of the Ten Questions were perfect or nearly perfect for severe and moderate (serious) disabilities. The positive predictive value was only 22% for serious disabilities, but 70% of children classified as false positives were found to have mild disabilities or other conditions (such as ear infections) for which early detection and treatment could be beneficial. No major age or gender differences in the validity of the questionnaire were apparent, but this finding needs additional study and confirmation with studies based on larger samples. In general, the results indicate that the Ten Questions is a valid tool for screening serious disabilities in children and can potentially improve the efficiency of health services by reducing the number of children requiring attention from professionals. Future studies using the Ten Questions should foster greater attention to the dimensions of childhood disability as a public health problem in the less developed world.     

Inadvertent removal of foreign body via a flexible fiberoptic bronchoscope in a 4-year-old boy

We report the case of a 4-year-old child with an atypical presentation of an aspirated unwitnessed foreign body in the airway. During an attempt to obtain a biopsy of what appeared to be a mucosal growth, the foreign body was removed. This may be the first report of foreign body removal in a child this young, using a flexible fiberoptic bronchoscope. Pediatr Pulmonol. 1994; 18:51–52. © 1994 Wiley-Liss. Inc.     

An appraisal of the appropriateness of the indications for hysterectomy.

Over a five-year period, 197 hysterectomies were performed at King Khalid University Hospital (KKUH). Indications for the procedures vary from menstrual disorders and symptomatic fibroids to ovarian malignancy. The most common indication was found to be menorrhagia. Among multiple pre-operative indications, only the first listed major indication for hysterectomy was chosen. There were 145 abdominal and 52 vaginal hysterectomies and all were elective gynaecological procedures, majority of which were performed on women in their fourth and fifth decades of life. Verification of pre-operative diagnosis, when correlated with pathological findings, showed that some of the indications for the procedure deserve a more critical reappraisal. Since hysterectomy carries substantial economic and medical consequences, indications for undertaking the procedure deserve more careful scrutiny given the surgical and nonsurgical options that are currently available. There may be a need, therefore, to assess the appropriateness or otherwise of the use of hysterectomy in many of the patients in future.     

Reoperations with the Right Gastroepiploic Artery without Cardiopulmonary Bypass

A bstract The right gastroepiploic artery (RGEA) has been utilized as the bypass conduit on the inferior surface of the heart with a minimally invasive approach. Fourteen patients had reoperative coronary bypass surgery for severely symptomatic single-vessel disease of the right coronary artery. All surgeries were performed since May 1996. A small mid-line incision including splitting of the lower sternum gave excellent exposure. The inferior surface of the heart was dissected to expose and stabilize the target vessel. The heart rate was controlled with a diltiazem drip. Cardiopulmonary bypass was not necessary in any case. The right coronary artery was bypassed in three patients, the posterior descending artery branch in ten patients, and the terminal circumflex of the left coronary artery in one. After grafting, patency of the anastomosis was demonstrated by Doppler echocardiogram. Two patients had left anterior descending artery (LAD) grafts with LIMA (left mammary artery) and RGEA grafts performed simultaneously with two port access incisions. No patient had perioperative mortality or complications. No patient had recurrent angina. Doppler color echocardiographic imaging studies before discharge confirmed patency of the graft in 13 of 14 cases. In one case, the gastroepiploic artery could not be visualized. Angiographic visualization was positive in seven cases; seven patients were not studied yet. The gastroepiploic artery is an excellent conduit for vascularization of the inferior aspect of the heart. The operation can be done with a minimally invasive technique and without the use of cardiopulmonary bypass. This approach seems especially applicable in selective reoperative cases.     

Magnetic Resonance Imaging of Corticobasal Degeneration

Corticobasal degeneration (CBD) is an adult–onset, progressive parkinsonian syndrome with strikingly asymmetrical features, and signs and symptoms referable to both cerebral cortex and basal ganglia. Although once considered rare, it is now recognized with increasing frequency during life. Eight patients with clinically diagnosed CBD and 8 age– and sex–matched patients with Parkinson's disease underwent high–field–strength magnetic resonance imaging (MRI) of the brain. MRIs were graded by a blinded neuroradiologist using a semiquantitative (0–3) scale. MRI of patients with CBD revealed significantly greater T2–weighted signal hypointensity in the putamena and globi pallidi, and ventricular enlargement. When specifically sought, asymmetrical cortical atrophy was identified in 5 of 8 CBD patients. Increased T2–weighted lenticular signal hypointensity, ventricular enlargement, and asymmetrical cortical atrophy are supportive MRI findings of CBD.