Carrier density dependence of plasmon-enhanced nonradiative energy transfer in a hybrid quantum well-quantum dot structure.

An array of Ag nanoboxes fabricated by helium-ion lithography is used to demonstrate plasmon-enhanced nonradiative energy transfer in a hybrid quantum well-quantum dot structure. The nonradiative energy transfer, from an InGaN/GaN quantum well to CdSe/ZnS nanocrystal quantum dots embedded in an ~80 nm layer of PMMA, is investigated over a range of carrier densities within the quantum well. The plasmon-enhanced energy transfer efficiency is found to be independent of the carrier density, with an efficiency of 25% reported. The dependence on carrier density is observed to be the same as for conventional nonradiative energy transfer. The plasmon-coupled energy transfer enhances the QD emission by 58%. However, due to photoluminescence quenching effects an overall increase in the QD emission of 16% is observed.

In-band OSNR monitoring using a pair of Michelson fiber interferometers.

Two polarization-independent Michelson fiber interferometers with different optical delays were used to measure the in-band OSNR of an optical signal from 5 to 30 dB within an accuracy of 0.5 dB. Using an expansion of the amplitude autocorrelation function of the signal around zero delay, it was possible to perform measurements without any prior knowledge of the signal. The system is shown to be immune to the effects of modulation frequency (up to 10G), partially and fully polarized noise, chromatic dispersion and poorly biased modulators.

Polarization dependence of a GaAs-based two-photon absorption microcavity photodetector.

In this paper, the polarization response of a GaAs based two-photon absorption microcavity photodetector has been studied. The deviation in the dependence of the detector response from that of bulk GaAs is shown to be due to the birefringence of the cavity. A theoretical model based on the convolution of the cavity birefringence and the polarization dependence of two-photon absorption in GaAs is described and shown to match the measured polarization dependence of the microcavity detector very well.

Surgical experience with hepatic colorectal metastasis.

The outcome of 134 patients undergoing hepatic resection for colorectal metastasis was studied. Current follow-up was available in 98 per cent of patients, for more than 5 years in 58 patients, and totaling 360 patient-years. Patients (52% male) had an average age of 62 +/- 1 years (standard error of the mean). Time lapse between the primary colon surgery and hepatic resection was a median of 16 months and a mean of 19 +/- 1 months. Thirty-two (24%) were operated on within 6 months for both their primary tumor and hepatic metastasis. Intensive care unit and total hospital length of stay were a median of 1 and 7 days, respectively. Pathology reports demonstrated that on average there were 2.0 +/- 0.1 lesions, with the largest lesion measuring 4.4 +/- 0.2 cm. In 72 per cent of patients, the lesions were found in one lobe only. CEA was elevated in 83 per cent of patients preoperatively and was 60 +/- 11 ng/mL before and 4.0 +/- 0.5 ng/mL after hepatic resection. Patient survival was 81 per cent at 1 year, 50 per cent at 3 years, 36 per cent at 5 years, and 23 per cent at 10 years. Actual 5- and 10-year survival was 22 of 58 (38%) patients and 4 of 21 (19%) patients respectively. Disease-free survival was 58 per cent at 1 year, 27 per cent at 3 years, 16 per cent at 5 years, and 12 per cent at 7 years. Survival was much better for one to four lesions than for five or more lesions (P < 0.01). Several other potential risk factors did not affect survival, including whether the patient received chemotherapy after hepatic resection. There were 36 (43%) patients who recurred with hepatic involvement only, 27 (32%) including hepatic involvement and 21 (25%) with nonhepatic involvement only. There were 15 patients who went on to receive repeat hepatic resections, with a 5-year survival of 74 per cent and disease-free survival of 58 per cent. Hepatic resection provides the best outcome of any form of therapy for selected patients with isolated hepatic metastasis.

Comparison of arcuate-legged clipped versus sutured hepatic artery, portal vein, and bile duct anastomoses.

Attempts at improving anastomoses have included the development of stapling techniques. Our purpose was to evaluate arcuate-legged clipped versus standard sutured anastomoses of the hepatic artery (HA), portal vein (PV), and bile duct in a porcine liver transplantation model. Two groups of pigs were studied intraoperatively and 1 day after liver transplantation. A control group underwent sutured anastomosis of PV and HA with polypropylene and of bile duct with polydioxanone (n = 8). An experimental group underwent anastomoses with arcuate-legged clips (n = 8). We analyzed the time to perform anastomosis and flows before and at various time points after anastomosis. In addition, patency and histology of the anastomoses were evaluated 1 day after operation, including a fibrin-thrombosis score, medial injury, and inflammation score. Times to complete HA and PV anastomoses were not different between clipped and sutured groups. However, the time was shorter to complete bile duct anastomosis with clips than with sutures (6.3 +/- 1.1 minutes and 13.3 +/- 2.0 minutes, respectively). Flows through HA anastomoses were not different between groups, but flow through the PV was higher in clipped compared with sutured anastomosis (P = 0.06). Patency was 100 per cent with no leaks for all three anastomoses in both groups. Histologic data were similar between vascular anastomotic groups. Sutured bile duct anastomoses revealed mild smooth muscle injury in 75 per cent whereas clipped bile duct anastomoses displayed no smooth muscle injury. We conclude that arcuate-legged clipped anastomosis represents a viable option to sutured anastomoses of the PV, HA, and bile duct anastomoses. Bile duct anastomoses were completed in less than half the time and with less tissue damage documented histologically.

The effect of nutritional and hormonal supplementation on protein synthesis immediately after liver transplantation.

We have previously shown that immediately after liver transplantation (LT) the porcine recipient exhibits elevated plasma glucagon, increased fractional synthetic rate (FSR) of fibrinogen, and decreased FSR of fixed or structural liver proteins. The purpose of this study was to evaluate the effect of nutritional and hormonal supplementation on these observations 24 h after LT. Two groups of nine pigs were studied 1 day after LT using radioisotopic and arteriovenous difference techniques. A control group underwent LT with saline infusion and a supplemented group underwent LT with infusion of glucose, amino acids (6 and 1.06 mg/kg. min, respectively), and intraportal insulin (0.6 mU/kg. min) and glucagon (1.3 ng/kg. min). Primed constant infusions of [3H]leucine were used to determine leucine flux, an estimate of whole body protein breakdown, and fractional synthetic rates (FSR). The following changes were noted with supplementation: elevated plasma insulin (6 +/- 1 versus 29 +/- 4 microU/ml, control versus supplemented, respectively, P < 0.05), decreased glucagon to normal levels (323 +/- 65 versus 102 +/- 12 pg/ml, P < 0.05), decreased fibrinogen FSR (108 +/- 15 versus 70 +/- 6%/day, P < 0.025), and increased fixed liver protein FSR (8 +/- 1 versus 13 +/- 2%/day, P < 0.05, respectively). Albumin FSR was unaltered by supplementation (8 +/- 2 versus 6 +/- 1%/day, respectively). Nutritional and hormonal supplementation immediately after LT restored the measured protein synthesis in the allograft to near normal levels 1 day after transplantation.

Pulmonary vascular morphological changes in cirrhotic patients undergoing liver transplantation.

Cirrhosis and portal hypertension may be associated with pulmonary hypertension and pulmonary dysfunction. However, morphological pulmonary vascular lesions in patients with cirrhosis have not been well characterized morphometrically. We morphometrically evaluated pulmonary vessels in liver transplant recipients with pretransplantation cirrhosis and correlated our findings with pretransplantation cardiopulmonary function, postoperative course, and postmortem cardiopulmonary findings. Autopsy lung slides from 23 transplant recipients with pretransplantation cirrhosis were examined. External vessel diameter, intimal thickness, and arterial medial thickness were measured with a micrometer after pentachrome staining. The percent of total diameter comprised by intima or media was calculated for each vessel. Medical records were reviewed for smoking history, pretransplantation cardiopulmonary function testing, and postoperative course. Autopsy cases without liver or significant cardiopulmonary diseases, matched for age, sex, and smoking history, served as controls. Transplant recipients had significantly more pulmonary venous intimal thickening than matched controls (P <.0001). Sixty-five percent (15 of 23) of these patients had some degree of pretransplantation pulmonary dysfunction, defined by abnormalities in pulmonary function tests, oxygen saturation, and/or increased pulmonary artery pressures. However, the severity of venous intimal thickening did not correlate with the severity of pretransplantation pulmonary dysfunction. Arterial intimal and medial thickness were not statistically significantly different from controls. Pulmonary venous intimal thickening and resultant luminal impingement are morphological findings not previously described in this population. The arterial lesion, when present, is similar to that seen in pulmonary hypertension from other causes. These pulmonary vascular lesions may be implicated in pulmonary dysfunction in patients with cirrhosis and may be associated with increased posttransplantation cardiopulmonary morbidity and mortality.

Net hepatic glucose output is normal on postoperative day 1 after liver transplantation.

The liver plays a central role in carbohydrate metabolism and glucose homeostasis; therefore, the rapid recovery of glucose homeostasis after liver transplantation (LT) is important. The purpose of this study was to evaluate hepatic and whole-body glucose production (WBGP) on postoperative day 1 after LT using a combination of arteriovenous differences and radioisotope techniques. Two groups of female commercially bred pigs with an average body weight of 31.9 +/- 1.4 kg were studied. A control group (n = 6) underwent laparotomy. A transplanted group (n = 6) was submitted to LT. All pigs were instrumented with catheters placed in the carotid artery and the hepatic, portal, and jugular vein, and flow probes were placed around the hepatic artery and portal vein. WBGP was measured by a primed constant infusion of 3-[3H]glucose 1 day postoperatively. Plasma glucose was 89 +/- 6 versus 98 +/- 7 mg/dL in the control and transplanted groups, respectively. WBGP was increased by 42 per cent in the transplanted group (2.54 +/- 0.17 vs 3.62 +/- 0.39 mg/kg.min), but the net hepatic glucose output was not different between the control and the transplanted groups (1.53 +/- 0.28 vs 1.68 +/- 0.31 mg/kg.min). These results demonstrate that net hepatic glucose output was not different between the control and transplanted pigs, suggesting that LT does not compromise the ability of the liver to produce glucose. However, the WBGP was increased by 42 per cent in the transplanted group, suggesting either a significant contribution from another organ or a significant intrahepatic utilization of glucose.

Hepatic uptake of amino acids immediately after liver transplantation is well preserved despite altered plasma profiles.

BACKGROUND: The liver is one of the principal organs responsible for the uptake and release of amino acids in the body. The ability of the transplanted liver to clear plasma amino acids is associated with a functioning allograft. However, clinical assessment is limited by the inability to access the portal vein postoperatively. Therefore, using a porcine liver transplant model, we examined (1) the plasma levels of amino acids presented to the new hepatic allograft and (2) the capacity of the new allograft to clear these amino acids from the circulation. MATERIALS AND METHODS: Two groups of commercially bred pigs were studied: a control group (n = 8) underwent laparotomy and a transplanted group (n = 6) underwent orthotopic liver transplantation (LT) using veno-venous bypass. All pigs had catheters placed in the carotid artery and portal and hepatic veins and ultrasonic transit time flow probes placed around the hepatic artery and portal vein. Plasma profiles of 23 amino acids were analyzed by high-pressure liquid chromatography. Hepatic balances of amino acids, using arteriovenous difference techniques coupled with hepatic blood flows, were also analyzed on postoperative day 1. RESULTS: Neither portal vein blood flow (703 +/- 74 ml/min vs 666 +/- 82 ml/min) nor hepatic artery blood flow (322 +/- 43 ml/min vs 209 +/- 59 ml/min) was significantly different between the control and the transplanted groups, respectively. The transplanted group had significantly increased plasma levels of alanine (135 +/- 13 mumol/l vs 382 +/- 72 mumol/l), hydroxyproline (30 +/- 5 mumol/l vs 60 +/- 9 mumol/l), methionine (25 +/- 2 mumol/l vs 55 +/- 10 mumol/l), ornithine (36 +/- 5 mumol/l vs 141 +/- 33 mumol/l), phenylalanine (84 +/- 5 mumol/l vs 120 +/- 12 mumol/l), threonine (75 +/- 9 mumol/l vs 159 +/- 27 mumol/l), and tryptophan (17 +/- 2 mumol/l vs 31 +/- 4 mumol/l). The transplanted group also had significantly decreased plasma levels of isoleucine (122 +/- 12 mumol/l vs 85 +/- 8 mumol/l) and taurine (71 +/- 7 mumol/l vs 35 +/- 7 mumol/l). These individual amino acid changes were not accompanied by impairment in the net hepatic amino acid balance or the hepatic fractional extraction of amino acids between the two groups. CONCLUSION: These results suggest that the circumstances associated with liver transplantation alter the fasting amino acid profile immediately postoperatively. However, liver transplantation does not impair the normal hepatic allograft uptake of most plasma amino acids. Thus, the changes observed in the circulating levels of amino acids may represent alterations in nonhepatic production and/or utilization. Furthermore, altered plasma amino acid profiles following liver transplantation are not necessarily indicative of impaired hepatic allograft amino acid metabolism.

Mechanisms of hyperinsulinemia and hyperglucagonemia after liver transplantation.

These studies were undertaken to evaluate the mechanisms for changes in plasma insulin and glucagon levels observed post-liver transplantation. Two groups of pigs were studied: a control group (n = 8) underwent laparotomy and catheter placement in the carotid artery and portal and hepatic veins. Hepatic blood flow was measured by ultrasonic flow probes placed around the hepatic artery and portal vein. An experimental group (n = 8) underwent orthotopic liver transplantation and similar instrumentation. On Day 1 after surgery, an estimate of insulin and glucagon secretion and hepatic extraction was determined using arteriovenous difference techniques. Serum assays were performed for markers of hepatic and renal function. Plasma insulin levels of the transplanted pigs were higher in the carotid artery (4 +/- 1 microU/ml vs 7 +/- 1 microU/ml), but not in the hepatic vein (5 +/- 1 microU/ml vs 7 +/- 1 microU/ml) and in the portal vein (10 +/- 2 microU/ml vs 12 +/- 2 microU/ml). Arterial plasma C-peptide was significantly greater in the transplanted group (0.23 +/- 0.02 ng/ml vs 0.42 +/- 0.03 ng/ml); however, the molar ratio of C-peptide and insulin was not different between the two groups (3.6 +/- 0.9 vs 3.4 +/- 0.4). Plasma glucagon levels of the transplanted pigs were significantly elevated in the carotid artery (111 +/- 11 pg/ml vs 323 +/- 65 pg/ml), portal vein (221 +/- 27 pg/ml vs 495 +/- 69 pg/ml), and hepatic vein (142 +/- 15 pg/ml vs 395 +/- 58 pg/ml). The estimate of pancreatic secretion of insulin (115 +/- 28 microU/kg.min) vs 71 +/- 21 microU/kg.min) and glucagon (2.0 +/- 0.4 ng/kg.min vs 2.7 +/- 0.7 ng/kg.min) and the fractional hepatic extraction rate of insulin (35 +/- 8% vs 32 +/- 5%) were not different between the two groups. However, the hepatic fractional extraction rate of glucagon was significantly decreased in the transplanted group (25 +/- 5% vs 11 +/- 3%). Therefore, the hyperglucagonemia observed 24 hr following liver transplantation is partly due to reduced hepatic fractional extraction of glucagon while the hyperinsulinemia is mainly due to the nonhepatic clearance of insulin. We speculate that decreased renal function may contribute to the hyperinsulinemia, elevated C-peptide concentrations, and hyperglucagonemia.

Breast disease.

Breast diseases are a common aspect of primary care practice. Common benign and malignant breast diseases are reviewed. The evaluation of common breast problems is presented and current recommendations for diagnostic and screening mammography are discussed.

Establishment and characterization of a human non-secretory plasmacytoid cell line and its hybridization with human B cells.

A human non-secretory plasmacytoid cell line has been established for 6 years in more than 170 passages. Over 300 passages have been made from several early and late passages. The cell line is karyotypically normal, easily grown and has the characteristic features of a non-secretory plasmablast. Its characteristics suggest its use for hybridization by new methods as well as a study of its secretory defect. HPRT-negative phenotypic mutants can be derived from this line and a single polyploid clone has also been isolated. Hybridization with the HPRT+ and HPRT- lines X human B cells is described.