Ad-layers enhance graphene's performance

Graphene's performance as transparent conductor can be significantly enhanced by discontinuous ad-layers on top of a complete graphene sheet by providing highly efficient parallel pathways for carrier transport.

Role of modulation frequency in a hybrid Q-switched Nd:LuVO₄ laser with an acousto-optic modulator and a Cr⁴⁺:YAG saturable absorber

This study presents a hybrid Q-switched Nd:LuVO₄ laser with an acousto-optic modulator (AOM) and a Cr⁴⁺:YAG saturable absorber. The importance of the modulation frequency of the AOM in this dual-loss modulation system is examined with two distinct observations: (1) the periodic-ramp pulse characteristics with the modulation frequency, and (2) the existence of the intrinsic modulation frequency for minimizing the pulsewidth. The shortest pulsewidth and the highest peak power were 10.6 ns and 13.9 kW, respectively, at a pump power of 10 W. Compared with the passively Q-switched laser, which has a pulsewidth of 18.3 ns, the ratio of pulse compression reaches 42%. Finally, numerical simulations based on the rate equations are used to verify the experimental results.

Appropriate liver resection type for patients with the American joint committee on cancer classification T1 and T2 hepatocellular carcinoma

SYNOPSIS

Major liver resection prevents intrahepatic tumor recurrence in T2 hepatocellular carcinoma patients with microvascular invasion or daughter nodules.

BACKGROUND AND OBJECTIVES

There is no consensus on whether major or minor hepatectomy is better for hepatocellular carcinoma (HCC) patients. We investigated the outcomes of liver resection type in resectable HCC patients.

METHODS

Two hundred sixty-three HCC patients with Child-Pugh class A liver function who underwent curative hepatectomy were enrolled. Among them, 186 patients had pathologic stage T1 HCC and 77 had stage T2 HCC. Patients were also classed according to the type of resection (major or minor). Clinicopathologic characteristics and outcomes were compared.

RESULTS

Patients with T1 HCC who underwent major resection had a higher rate of blood transfusion than those who underwent minor resection (P < 0.001). The disease-free survival rate of T2 patients who underwent major resection was better than that of patients who underwent minor resection (P = 0.004). The overall survival rates of T1 and T2 HCC patients did not differ significantly between those with major or minor resection.

CONCLUSIONS

Major liver resection is recommended for T2 HCC patients with adequate remnant liver function because it results in a better disease-free survival rate than does minor resection in these patients. Minor liver resection is suggested for T1 HCC patients, except for those with a tumor sitting close to vessels, because it is associated with a low incidence of blood transfusion and a good survival rate.

Aristolochic acid I induced oxidative DNA damage associated with glutathione depletion and ERK1/2 activation in human cells

Aristolochic acid I (AAI) has been widely found in herbal remedies and linked to the development of nephropathy and urothelial carcinoma in humans. This study elucidated the mechanism of oxidative stress and DNA damage mediated by AAI in human cells. Treatment of human promyelocytic leukemia cells (HL-60) and human renal proximal tubular cells (HK-2) with AAI led to a dose-dependent increase of reactive oxygen species (ROS). AAI also elevated the levels of DNA strand breaks and 8-hydroxy guanosine in HL-60 and HK-2 cells. Antioxidants, including Tiron, N-acetyl-l-cysteine (NAC) and glutathione (GSH), effectively suppressed the AAI-induced ROS and AAI-elicited genotoxicity, indicating that AAI induced the DNA damage through oxidative stress. GSH depletion was also found in AAI-treated cultures and proceeded prior to ROS formation. Exposure of HL-60 cells with AAI activated both ERK1/2 and p38 kinase phosphorylation, while only MEK1/2 inhibitor, U0126, significantly decreased AAI-mediated ROS. Preincubation of cells with thiol-containing compounds (NAC and GSH) inhibited the caspase 3 activity triggered by AAI, but non-thiol Tiron did not show a similar effect. This study demonstrated that AAI treatment results in oxidative stress-related DNA damage through GSH depletion and ERK1/2 activation; AAI-induced apoptosis is associated with GSH loss, but is independent of ROS generation.

Radiofrequency ablation after transarterial embolization as therapy for patients with unresectable hepatocellular carcinoma

PURPOSE

To evaluate the usefulness of transcatheter arterial embolization (TAE) followed by radiofrequency ablation (RFA) as combined treatment for unresectable hepatocellular carcinoma (HCC).

PATIENTS AND METHODS

Thirty-six consecutive patients (cirrhosis, Child-Pugh class A or B) with solitary or oligonodular HCC were treated (41 lesions; mean size, 58.9 mm; range, 30-120 mm). RFA was performed after one TAE treatment. Local efficacy was evaluated with multiphasic computed tomography (CT) performed an average of two months after RFA and once during later follow-up.

RESULTS

The mean follow-up period was 16 months (range, 2-45 months). Technical success (namely, complete tumor devascularization during the arterial phase) was achieved for 59% of lesions at the first CT evaluation and for 46% at the second evaluation. Among prognostic factors included in the analysis, only lesion diameter (< 50 mm versus > or = 50 mm) was statistically significant in terms of predicting local success (Fisher's exact test: 85% versus 43% at first CT, p<0.01; 70% versus 36% during follow-up, p=0.05). There were no major periprocedural complications. Kaplan-Meier analysis showed survival rates of 84% at 12 months and 57% at 24 months.

CONCLUSIONS

Combined therapy--TAE then RFA--for unresectable HCC lesions in patients with cirrhosis produces a relatively high complete local response rate compared with TAE or RFA alone. Our results, considered with those from other case series, may help design prospective, randomized clinical trials to test combination therapy versus single-modality therapy in terms of risks and benefits.

Current and strain-induced spin polarization in InGaN/GaN superlattices

The lateral current-induced spin polarization in InGaN/GaN superlattices (SLs) without an applied magnetic field is reported. The fact that the sign of the nonequilibrium spin changes as the current reverses and is opposite for the two edges provides a clear signature for the spin Hall effect. In addition, it is discovered that the spin Hall effect can be strongly manipulated by the internal strains. A theoretical work has also been developed to understand the observed strain-induced spin polarization. Our result paves an alternative way for the generation of spin polarized current.

Intrapericardial isolation of the inferior vena cava through a transdiaphragmatic pericardial window for tumor resection without sternotomy or thoracotomy

AIMS

The prognosis for patients with advanced tumors invading the inferior vena cava (IVC) is dismal and surgical treatments for these tumors are challenging. A surgical approach that avoids sternotomy and thoracotomy for tumors invading the IVC even to the level of the hepatocaval junction would be extremely helpful.

METHODS

The intrapericardial IVC was isolated via a transdiaphragmatic pericardial window using a transabdominal approach. Hepatectomy was then applied via an anterior approach until the IVC was seen. Total hepatic vascular exclusion was achieved by clamping the portal triad, intrapericardial IVC and infrahepatic IVC. We removed the primary tumor, the liver portion involved and the tumor thrombi, with segmental resection of the IVC. Vascular continuity was reestablished using a 20-mm-diameter polytetrafluoroethylene graft.

RESULTS

Four patients with tumors invading the IVC were treated with this method. All underwent gross en-bloc tumor resections and all survived.

CONCLUSION

This method for the resection of IVC tumors could avoid emboli dislodging from the tumor thrombi, prevent the complications of sternotomy, cardiopulmonary bypass and shorten operative times.

Comparison of clinical staging systems in predicting survival of hepatocellular carcinoma patients receiving major or minor hepatectomy

AIM

To compare the utility of seven commonly used staging systems in the prediction of survival among patients with hepatocellular carcinoma (HCC) undergoing major or minor hepatectomy.

METHODS

All patients were classified by the Okuda, the TNM, the CLIP, the BCLC, the CUPI, the JIS and the MELD classifications to estimate the probabilities of survival. Survival curves were calculated using the Kaplan-Meier method and were examined using log-rank testing. The overall predictive power for patient survival with each staging system was evaluated using linear trend chi(2) tests and from the area under the receiver operating characteristic (ROC) curve.

RESULTS

In our patient cohort, the log-rank test and the linear trend chi(2) test of the CLIP and JIS systems gave better results than did the other staging systems. The discriminatory ability of the CLIP and JIS staging for death, evaluated by ROC curve areas, was also better. In the subgroups of major hepatectomy patients with a non-cirrhotic liver or minor hepatectomy patients with a cirrhotic liver, the CLIP and JIS systems showed similar better performances in these three tests. The discriminatory ability of the CLIP system was the best in major hepatectomy patients with a non-cirrhotic liver while JIS score discriminated best in minor hepatectomy patients with a cirrhotic liver.

CONCLUSION

Among the seven staging systems, the CLIP and JIS systems perform better than do the others. While the CLIP system should be considered to stage major hepatectomy patients, the JIS system could be chosen to stage minor hepatectomy patients.

An alternative technique for totally implantable central venous access devices. A retrospective study of 1311 cases

AIM

The aim of the present study was to report our experience of totally implantable central venous access devices (TICVAD) implantation using two techniques and attempt to define the better technique.

MATERIALS AND METHODS

From January 1998 to September 2003, 1131 patients were reviewed and divided into two groups with implantation by cephalic vein cut-down (group A) done by general surgeons and subclavian vein puncture with the Seldinger technique (group B) done by vascular surgeons. The operative time, early and late complications of these two groups were compared. Data were analysed by Student's t-test.

RESULTS

The average of operative time was 43 min in group A (35-70 min) and 40 min in group B (35-60 min) (P>0.05). No post-operative pneumothorax, hemothorax and fragmentation occurred in group A; the incidence of peri-operative complication was higher in group B. The overall and early complications of group A were significantly lower than that of group B (P<0.0001).

CONCLUSION

This retrospective study showed that the cephalic vein cut-down approach for TICVAD placement avoided the risks of pneumothorax, hemothorax and catheter fragmentation.

Prediction of the risk of hepatic failure in patients with portal vein invasion hepatoma after hepatic resection

AIM

Hepatic failure can develop after curative hepatectomy in patients with a hepatocellular carcinoma (HCC) invading the portal vein, because of cirrhosis and excessive tissue loss. This study aimed to identify the risk factors for hepatic failure in such patients.

METHOD

Forty patients with an HCC invading the portal vein underwent curative hepatectomy from January 1995 to June 2003. Eight patients developed hepatic failure and died within 3 months. Possible risk factors for this were analysed using univariate and multivariate regression. These included the liver function index, surgical blood loss, tumour pattern, portal hypertension, estimated residual liver volume measured by computed tomography (ERLV(CT)) and estimated residual liver volume using the indocyanine green (ICG) retention rate at 15 min (ERLV(ICG15)).

RESULTS

The ERLV(CT) smaller than the ERLV(ICG15) and presence of portal hypertension were independent risk factors for post-hepatectomy hepatic failure.

CONCLUSION

Having portal vein invasion HCC with portal hypertension or an ERLV(CT) less than an ERLV(ICG15) are significant predictors of post-hepatectomy hepatic failure. These factors are important considerations for patients with portal vein invasion HCC who could undergo curative hepatic resection.

The effects of weight reduction on the rehabilitation of patients with knee osteoarthritis and obesity

OBJECTIVE

To evaluate the effect of weight reduction on the rehabilitation of patients with knee osteoarthritis and obesity.

METHODS

A total of 126 patients with bilateral knee osteoarthritis and obesity were classified into 3 groups by their stages of osteoarthritis. Each group was divided into subgroups a, b, and c. The subjects in subgroup a received weight reduction treatment, those in subgroup b received weight reduction and electrotherapy modalities, and those in subgroup c received electrotherapy modalities to relieve pain.

RESULTS

Pain reduction, weight reduction, ambulation speed, and changes of Lequesne's index were greater in patients in subgroups a and b than in subgroup c after treatment. Although the last pain scores in subgroup b were less than those in subgroup a, as measured by a visual analog scale (VAS), there was no significant difference between their functional status. Significant pain relief (VAS < 2) and an acceptable functional status (Lequesne's index < 7) were indicated when weight reduction was more than 15% and 12%, respectively, of the initial body weight of the individual.

CONCLUSION

Weight reduction was found to be a practical adjuvant treatment in the rehabilitation of patients with knee osteoarthritis.

Interpretation of skull radiographs for facial fractures by medical staff working in UK emergency departments: a pilot study

OBJECTIVES

This was a pilot study to determine the ability of hospital doctors (1) to assess the technical quality of occipitomental (OM) radiographs and (2) to identify facial fractures.

METHOD

Twenty-two doctors from four UK Accident and Emergency (A&E) departments participated in a two part study: Part A was a postal questionnaire containing questions on demographic data, educational background, selection criteria, assessing radiographs and radiation protection; and Part B was a clinical viewing session to interpret 20 randomized OM radiographs divided into four groups; technically good and poor without fractures, and technically good and poor with fractures.

RESULTS

Study participants ranged from junior house officers to senior consultants. There was considerable variation in educational background and radiographic interpretation instruction at undergraduate and postgraduate level. OM radiographs constituted 10% of all skull radiographs examined per week, yet only 40% of the doctors felt confident when assessing technical quality. The majority of participants had only a limited knowledge of radiation protection legislation. During the viewing session, only 50% of the participants correctly identified those radiographs with fractures and those with technique errors. There was no significant difference between house officers and other grades of staff. A higher level of seniority did not equate with greater interpretative ability. Subjective confidence in assessing film quality did not correlate with the actual film viewing.

CONCLUSION

Only half of the A&E doctors taking part in the study were able to correctly assess film quality and identify facial fractures on OM radiographs. If the pilot sample is representative, then the findings are of considerable concern.

The effect of surgical stress on insulin sensitivity, glucose effectiveness and acute insulin response to glucose load

Hyperglycemia after stress is a very common clinical phenomenon. It is generally hypothesized that the underlying cause is a neuroendocrine-mediated deterioration in glucose metabolism. However, the detailed roles of insulin sensitivity, glucose effectiveness and acute insulin response to glucose load in response to stress have not been well established. Hernioplasty was used as a minor stress model for studying stress-induced hyperglycemia. Eleven healthy young men were enrolled voluntarily in this study. Their mean age was 22.0 +/- 0.9 yr and BMI 23.3 +/- 0.6 kg/m2. Frequently sampled i.v. glucose tolerance tests were performed one day before and one day after the surgery. Insulin sensitivity (SI), glucose effectiveness (EG) and area under acute insulin response (AIR) were calculated from "minimal model" algorithms. We also measured fasting concentrations of human GH, ACTH and F on the days of the test. Compared to the pre-operation data, levels of ACTH and F did not change significantly after the surgery. Only GH levels were marginally significant. On the other hand, the SI (0.75 +/- 0.1, 0.52 +/- 0.9 x 10(-5) min(-1)/pmol, p = 0.04), EG (0.023 +/- 0.03, 0.016 +/- 0.003 min(-1), p = 0.01) and AIR (6738.5 +/- 1111.6, 5130.0 +/- 1047.2 pmol, p = 0.005) were all significantly decreased after surgery. The percentages of decrease were 16.3 +/- 15.5, 32.1 +/- 10.3 and 17.8 +/- 10.3%, respectively. Finally, only the changes of EG positively correlate with the changes of ACTH before and after surgery. No significant changes were noted among other stress hormones and the changes of SI, EG and AIR. In conclusion, hernioplasty results in reduced SI, EG and AIR. Among them, although not statistically significant, the EG showed the most distinct decrease after the surgery, which has not been found in previous literature.

Thiamine deficiency and unexplained encephalopathy in hemodialysis and peritoneal dialysis patients

Patients with end-stage renal disease undergoing regular dialysis are prone to encephalopathy, but the cause is often unclear. Dialysis patients are at risk for thiamine deficiency, which may mimic many uremic complications, including encephalopathy. To determine whether unexplained encephalopathy in regular dialysis patients is associated with thiamine deficiency, we conducted a prospective study that enrolled 30 consecutive dialysis patients with altered mental status admitted to a referred hospital during a 1-year period. A complete history, physical and neurological examinations, laboratory investigations, and computed tomographic scans or magnetic resonance imaging of the brain were obtained for each subject. In 10 of the 30 patients, diagnoses remained obscure after the initial workup. Manifestations included confusion, chorea, acute visual loss, rapidly progressive dementia, myoclonus, convulsions, and coma. Intravenous thiamine was administered to these 10 patients. All 10 patients had thiamine deficiency confirmed by a marked response to thiamine supplementation and/or a low serum thiamine concentration (35.3 +/- 6.0 nmol/L; normal, >50 nmol/L). Nine patients recovered, but one patient failed to respond because of delayed treatment. We conclude that in regular dialysis patients, unexplained encephalopathy can be mainly attributed to thiamine deficiency. This condition is fatal if unrecognized and can be successfully treated with prompt thiamine replacement.

Optical emissions in a sonoluminescing bubble

We study how the mechanism of spontaneous decay of atoms (or molecules) in a sonoluminescing bubble (SLB) can be affected by the high density and high temperature environment resulting from the rapid collapse of the gas bubble immediately prior to light emission. We present a detailed study of the density of states of photons in multiple-layered spheres, which mimic various stages of a SLB. In particular, we found that the spontaneous decay rate could be strongly enhanced in the presence of a thin plasma shell inside the bubble, which was predicted recently in numerical hydrodynamic simulations of a SLB.

Human peritoneal mesothelial cells produce nitric oxide: induction by cytokines

OBJECTIVE

To investigate the induction of nitric oxide synthase type II (iNOS) in human peritoneal mesothelial cells (HPMC) using cytokines and bacterial lipopolysaccharide (LPS).

DESIGN

Confluent monolayers of HPMC were exposed to cytokines [tumor necrosis factor alpha (TNFalpha), interleukin-1 beta (IL-1beta), interferon gamma (IFNgamma)] or LPS, individually or in various double and triple combinations, for 24-72 hours. Concentrations of nitrate and nitrite in the media were quantified using the Griess reaction and used as indirect indices of nitric oxide (NO) production. The expression of iNOS was assessed using reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot.

RESULTS

Neither single cytokines nor LPS was able to induce iNOS mRNA or NO production. Both double combinations of TNFalpha + IFNgamma and IL-1beta + IFNgamma were able to induce iNOS mRNA expression, but only TNFalpha + IFNgamma induced significant NO production. The triple combination of TNFalpha + IFNgamma + IL-1beta induced even more NO production than TNFalpha + IFNgamma. There was no constitutive NO synthase type III (eNOS) expression in HPMC.

CONCLUSIONS

Certain combinations of cytokines could stimulate cultured HPMC to produce NO, and HPMC might be a source of intraperitoneal NO production during peritonitis.