A Detailed Investigation of the Onion Structure of Exchanged Coupled Magnetic Fe3-δO4@CoFe2O4@Fe3-δO4 Nanoparticles

Nanoparticles that combine several magnetic phases offer wide perspectives for cutting edge applications because of the high modularity of their magnetic properties. Besides the addition of the magnetic characteristics intrinsic to each phase, the interface that results from core-shell and, further, from onion structures leads to synergistic properties such as magnetic exchange coupling. Such a phenomenon is of high interest to overcome the superparamagnetic limit of iron oxide nanoparticles which hampers potential applications such as data storage or sensors. In this manuscript, we report on the design of nanoparticles with an onion-like structure which has been scarcely reported yet. These nanoparticles consist of a Fe_3-δO₄ core covered by a first shell of CoFe₂O₄ and a second shell of Fe_3-δO₄, e.g., a Fe_3-δO₄@CoFe₂O₄@Fe_3-δO₄ onion-like structure. They were synthesized through a multistep seed-mediated growth approach which consists consists in performing three successive thermal decomposition of metal complexes in a high-boiling-point solvent (about 300 °C). Although TEM micrographs clearly show the growth of each shell from the iron oxide core, core sizes and shell thicknesses markedly differ from what is suggested by the size increasing. We investigated very precisely the structure of nanoparticles in performing high resolution (scanning) TEM imaging and geometrical phase analysis (GPA). The chemical composition and spatial distribution of atoms were studied by electron energy loss spectroscopy (EELS) mapping and spectroscopy. The chemical environment and oxidation state of cations were investigated by ⁵⁷Fe Mössbauer spectrometry, soft X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD). The combination of these techniques allowed us to estimate the increase of Fe²⁺ content in the iron oxide core of the core@shell structure and the increase of the cobalt ferrite shell thickness in the core@shell@shell one, whereas the iron oxide shell appears to be much thinner than expected. Thus, the modification of the chemical composition as well as the size of the Fe_3-δO₄ core and the thickness of the cobalt ferrite shell have a high impact on the magnetic properties. Furthermore, the growth of the iron oxide shell also markedly modifies the magnetic properties of the core-shell nanoparticles, thus demonstrating the high potential of onion-like nanoparticles to accurately tune the magnetic properties of nanoparticles according to the desired applications.

Result and cost of hepatic chemoembolisation with drug eluting beads in 21 patients

PURPOSE

The aim of our study was to assess the results and cost of a treatment strategy involving transarterial chemoembolisation with drug eluting beads (DEB-TACE) in patients with unresectable non-metastatic hepatocellular carcinoma (HCC).

PATIENTS AND METHODS

This study included all patients treated with DEB-TACE in our hospital between January 2009 and December 2010. All patients received DEB-TACE on demand and were evaluated after each session.

RESULTS

Twenty-one patients received an average of 1.3 sessions. The median time to treatment discontinuation and median progression-free survival was 181 days and 295 days, respectively. Toxicity caused treatment discontinuation in three patients (14%). For the hospital, the average direct cost of treatment was €6,033 according to the analytical accounting system vs. €4,558 according to the official tariffs from the new French Diagnosis-Related Group prospective payment system (P=0.002).

CONCLUSION

In the treatment of HCC, on-demand DEB-TACE stabilises the disease in some patients but has not yet been thoroughly evaluated.

Collapsing focal segmental glomerulosclerosis in a liver transplant recipient on alendronate

We describe a case of collapsing focal segmental glomerulosclerosis and severe kidney dysfunction in a liver transplant recipient after the initiation of alendronate for osteopenia. In view of the increasing incidence of chronic kidney disease in long-term liver transplant patients, bisphosphonates need to be used with caution in these patients. The usefulness of bisphosphonates for the prevention of early bone loss after liver transplantation is increasingly reported. However, there is little information on the safety and efficacy of these drugs when used in the later stages of liver transplant, particularly in the presence of chronic kidney disease. Bisphosphonates are excreted unchanged via the kidneys after reaching the systemic circulation. Some cases of severe kidney injury, in particular collapsing focal segmental glomerulosclerosis, have been described that are associated with the use of pamidronate. Alendronate, a widely used bisphosphonate in transplant patients, has not been related to kidney toxicity. We describe a case of collapsing focal segmental glomerulosclerosis and severe kidney dysfunction in a liver transplant recipient soon after the initiation of alendronate for osteopenia. Possible pathogenetic mechanisms are discussed. In view of the increasing incidence of chronic kidney disease in long-term liver transplant patients, bisphosphonate need to be used with caution in patients with a low glomerular filtration rate.

[Postoperative cognitive disorders in the elderly]

TWO DISTINCT CATEGORIES: Postoperative cognitive disorders include delirium and long-term cognitive dysfunction. DELERIUM: Delirium is an acute state occurring early during the postoperative period. It may be considered as an acute cerebral insufficiency which may be consecutive both to the negative effects of aging and chronic illness on cognitive function, and to the cerebral impact of operative stress. In addition, precipitating postoperative medical factors may facilitate cerebral failure. Only a few studies have been devoted to prevention programs aimed at reducing the risk of postoperative delirium. Nevertheless, we can hypothesize that a preoperative gerontology assessment would be effective in determining risk factors of delirium in old patients and thus enable proposing individual postoperative management. LONG-TERM COGNITIVE DYSFUNCTION: The definition of this clinical picture is less precise than delirium. Long-term cognitive dysfunction corresponds to a loss of cognitive performance in the weeks and months after anesthesia. The IPOCD1 study conducted in a large cohort of elderly patients has shown that postoperative cognitive dysfunction was present in 25.8% of patients 1 week after surgery and in 9.9% 3 months after surgery. One to two years after surgery, cognitive dysfunction was observed in 10.4% of patients compared with 10.6% in a control population of non-operated patients. We would suggest that in many cases, postoperative cognitive dysfunction may result from preoperative dementia unmasked by surgery.

Liver transplantation from controlled non-heart-beating donors

BACKGROUND

The use of organs from non-heart-beating donors (NHBDs) has been proposed as one way to increase the donor pool. However, few centers have transplanted livers from NHBDs. We report here the results of 19 liver transplants from controlled NHBDs.

METHODS

From January 1993 through August 1999, 364 liver transplantations were performed from heart-beating donors (HBDs) and 19 liver transplantations were performed from NHBDs. Donor and recipient characteristics, posttransplant complications, and patient and allograft survival were compared.

RESULTS

No differences in hepatic artery, portal vein, or biliary complications were noted between the groups. However, the rate of primary nonfunction was higher in recipients of livers from NHBDs (10.5% vs. 1.3%; P = .04). No difference in patient survival was seen between recipients of NHBDs or HBDs (72.6% vs. 84.8%; P =.36); however, allograft survival was lower in recipients who received livers from NHBDs (53.8% vs. 80.9%; P =.007).

CONCLUSIONS

Liver transplantation from controlled NHBDs results in similar patient survival and post-transplant complications. However, primary nonfunction was higher and allograft survival was less in recipients of livers from NHBDs. The results of liver transplantation from controlled NHBDs are encouraging and should continue to be cautiously pursued as one way to help alleviate the current shortage of donor livers.

Long-term results of liver transplantation in older patients 60 years of age and older

BACKGROUND

Advances in perioperative care and immunosuppression have enabled clinicians to broaden the indications for organ transplantation. Advanced age is no longer considered a contraindication to transplantation at most centers. Although short-term studies of elderly liver transplant recipients have demonstrated that the incidence of complications and overall patient survival are similar to those of younger adults, transplant center-specific, long-term data are not available.

METHODS

From August of 1984 to September of 1997, 91 patients 60 years of age or older received primary liver transplants at the University of Wisconsin, Madison. This group of patients was compared with a group of younger adults (n=387) ranging in age from 18 to 59 years who received primary liver transplants during the same period. The most common indications for transplantation in both groups were Laennec's cirrhosis, hepatitis C, primary biliary cirrhosis, primary sclerosing cholangitis, and cryptogenic cirrhosis. There was no difference in the preoperative severity of illness between the groups. Results. The length of hospitalization was the same for both groups, and there were no significant differences in the incidence of rejection, infection (surgical or opportunistic), repeat operation, readmission, or repeat transplantation between the groups. The only significant difference identified between the groups was long-term survival. Five-year patient survival was 52% in the older group and 75% in the younger group (P<0.05). Ten-year patient survival was 35% in the older group and 60% in the younger group (P<0.05). The most common cause of late mortality in elderly liver recipients was malignancy (35.0%), whereas most of the young adult deaths were the result of infectious complications (24.2%).

CONCLUSION

Although older recipients at this center did as well as younger recipients in the early years after liver transplantation, long-term survival results were not as encouraging.

Surgical portosystemic shunts for treatment of portal hypertensive bleeding: outcome and effect on liver function

BACKGROUND

Since the advent of liver transplantation and transjugular intrahepatic portosystemic shunts (TIPS), the role of surgical portosystemic shunts in the treatment of portal hypertension has changed. However, we have continued to use portosystemic shunts in patients with noncirrhotic portal hypertension and in patients with Child's A cirrhosis.

METHODS

We performed 48 surgical portosystemic shunt procedures between 1988 and 1998. The outcomes of these patients were evaluated to assess the efficacy of this treatment. Data from 39 of 48 patients were available for analysis. The average follow-up was 42 months.

RESULTS

Liver function generally remained stable for the patients; only 2 patients had progressive liver failure and required transplant procedures. Gastrointestinal bleeding (3 patients), encephalopathy (3 patients), and shunt thrombosis (3 patients) were rare. Patient survival was 81% at 4 years, similar to survival with liver transplantation (P = .22).

CONCLUSIONS

Surgical shunts remain the treatment of choice for prevention of recurrent variceal bleeding in patients with good liver function and portal hypertension.

Liver transplantation as definitive therapy for complications after arterial embolization for hepatic manifestations of hereditary hemorrhagic telangiectasia

Experience with hepatic artery embolization for the treatment of symptomatic hepatic arteriovenous malformations (AVMs) in Rendu-Osler-Weber disease is limited. We report 2 cases of hepatic AVMs that caused mesenteric angina-like symptoms that were treated with embolization. Both patients developed parenchymal and bile duct necrosis, intrahepatic bilomas, and refractory biliary sepsis, subsequently leading to liver failure. We hypothesize that the pathophysiological cause of biliary necrosis in this setting is similar to that which occurs in the setting of hepatic artery thrombosis of the liver allograft. Progressive liver failure in these patients was treated successfully by liver transplantation. Liver transplantation offers definitive therapy by removing the source of ongoing sepsis, restoring normal liver function, and eliminating the intrahepatic AV shunt.

Aspects on the role of tachykinins and vasoactive intestinal polypeptide in control of secretion, motility and blood flow in the gut

Both intrinsic and extrinsic neurons of the gut respond to mechanical and chemical stimuli by the release of neurotransmitters. We summarize here some of our recent work on the role of vasoactive intestinal polypeptide (VIP), substance P (SP) and neurokinin A (NKA) in the secretory, motor and vascular effects of hydrochloric acid stimulation in the isolated rat duodenal loop and electrical nerve stimulation and mechanical stimulation of the cat colon. Isolated duodenal loops of conscious rats were perfused with isotonic saline, and challenged at hourly intervals with brief exposures to increasing concentrations of HCL. The concentrations of bicarbonate and prostaglandin E2 (PGE2) released from the duodenal mucosa were significantly augmented already by pH 5.0 whereas VIP was significantly augmented at pH 3.0 and the tachykinins SP and NKA at pH 2.0. Continuous electric stimulation of the pelvic nerve in cats at 4 Hz during 1 s with 10 s rest produced a marked release of NKA-LI and SP-LI from the colon to blood. Reflex activation of the pelvic nervae by mechanical stimulation of the anus or rectal distension produced a less pronounced release of NKA-LI and SP-LI from the colon to blood. There was a simultaneous colonic contraction and vasodilation during each nerve stimulation. Close intraarterial infusions of NKA, neurokinin B, SP, neuropeptide K (NPK), eledoisin and physalemin at doses of 0.1-100 pmol/min induced dose-dependent proximal and distal colonic contractions and vasodilation, NKA being the most potent. The effects of the tachykinins were reduced after tetrodotoxin and atropine, but unchanged after treatment with hexamethonium.(ABSTRACT TRUNCATED AT 250 WORDS)