Syntheses and evaluation of new hydrophilic azacryptands used as masking agents of technetium in solvent extraction processes.

The extraction of technetium, present in nitric acid medium as pertechnetate anion, is an issue in solvent extraction processes used to recover uranium and plutonium. In the present study, a complexing agent is added in the aqueous nitric acid solution to bind selectively the pertechnetate anion and prevent its extraction into the organic phase or to back extract it in the aqueous phase. Several azacryptands with the addition of hydrophilic groups were synthesized to improve the solubility of the previously studied cage molecule in nitric acid medium.

Synergistic Self-Assembly of Oxoanions and d-Block Metal Ions with Heteroditopic Receptors into Triple-Stranded Helicates.

Cooperativity effects among the interconnected anion and cation binding sites can profoundly alter the performance of heteroditopic receptors in selective ion pair recognition, processes that are oftentimes pertinent to biological systems and chemical separations. This work reports the effect of the linker that connects both binding sites on self-assembly of heteroditopic receptors in the presence of divalent first-row transition metal salts in solution and solid phase. Introduction of backbone flexibility in the receptor results in the formation of triple-stranded ion-pair helicates with an extraordinary selectivity towards CuSO through an anion-induced fit.

Perrhenate and pertechnetate complexation by an azacryptand in nitric acid medium.

Technetium is present as the pertechnetate anion in spent nuclear fuel solutions, and its extraction by several extractant systems is a major problem for the liquid-liquid extraction processes used to separate uranium and plutonium. To prevent technetium extraction into the organic phase, a complexing agent may be added to the aqueous nitric acid phase to selectively bind the pertechnetate anion. In the present study, liquid-liquid extraction experiments reveal that technetium distribution ratios are considerably lowered with addition of an azacryptand, which is a good receptor for pertechnetate anion recognition.

Evidence that the amyloid-β protein precursor intracellular domain, AICD, derives from β-secretase-generated C-terminal fragment.

One of the major pathological hallmarks of brains affected with Alzheimer's disease (AD) is the senile plaque, an extracellular deposit mainly composed of a set of highly insoluble peptides of various lengths (39-43 amino acids) referred to as amyloid-β (Aβ) peptides. Aβ peptides are derived from combined proteolytic cleavages undergone on the amyloid-β protein precursor (AβPP) by a set of enzymes called secretases. Several lines of anatomical and biological evidence suggest that Aβ peptides would not account for all pathological stigmata and molecular dysfunctions taking place in AD.

α-Secretase-derived fragment of cellular prion, N1, protects against monomeric and oligomeric amyloid β (Aβ)-associated cell death.

In physiological conditions, both β-amyloid precursor protein (βAPP) and cellular prion (PrP(c)) undergo similar disintegrin-mediated α-secretase cleavage yielding N-terminal secreted products referred to as soluble amyloid precursor protein-α (sAPPα) and N1, respectively. We recently demonstrated that N1 displays neuroprotective properties by reducing p53-dependent cell death both in vitro and in vivo. In this study, we examined the potential of N1 as a neuroprotector against amyloid β (Aβ)-mediated toxicity.

Low-frequency stimulation of the hippocampus following fear extinction impairs both restoration of rapid eye movement sleep and retrieval of extinction memory.

Post-learning rapid eye movement (REM) sleep deprivation has often been shown to impair hippocampal functioning, which results in deficit in retrieval of some types of memory. However, it remains to be determined whether post-learning alteration of hippocampal functioning affects, in turn, REM sleep. Recent studies have shown that both post-extinction REM sleep deprivation and post-extinction application of hippocampal low-frequency stimulation (LFS) impair memory of fear extinction, indicating possible bidirectional interactions between hippocampal functioning and REM sleep.

Hippocampal train stimulation modulates recall of fear extinction independently of prefrontal cortex synaptic plasticity and lesions.

It has been shown that long-term potentiation (LTP) develops in the connection between the mediodorsal thalamus (MD) and the medial prefrontal cortex (mPFC) and between the hippocampus (HPC) and the mPFC following fear extinction, and correlates with extinction retention. However, recent lesion studies have shown that combined lesions of the MD and mPFC do not interfere with extinction learning and retention, while inactivation of the dorsal HPC disrupts fear extinction memory. Here we found in rats that immediate post-training HPC low-frequency stimulation (LFS) suppressed extinction-related LTP in the HPC-mPFC pathway and induced difficulties in extinction recall.

[C. Walton Lillehei and the epic of open heart surgery].

C. Walton Lillehei (1918-1999) from the Surgery Department of the University of Minnesota in Minneapolis (MN, USA), was the precursor of open heart surgery. He successively introduced heart-lung machine, intracardiac repairs, pacemaker, and mechanical cardiac valves.

Influence of post-surgery time after cardiac transplantation on exercise responses.

Influence of post-surgery time after cardiac transplantation on exercise responses. Med. Sci.

Long term follow up of 292 patients after valve replacement with the Omnicarbon prosthetic valve.

In a prospective study, 292 consecutive patients received 336 Omnicarbon cardiac valves from September 1984 through September 1992 at the Montpellier University Hospital. There were 153 aortic (52%), 95 mitral (33%) and 44 double (15%) mitral and aortic replacements. Mean age was 58 years; 57% were male.

Surgical treatment of extracranial internal carotid artery aneurysm.

Aneurysms of the extracranial internal carotid artery are rare but can be responsible for severe complications such as rupture, thrombosis, or embolism. Between 1961 and 1985 we operated on 38 aneurysms of the extracranial internal carotid artery in 35 patients, 22 males and 13 females, whose ages ranged from 6 to 73 years. The underlying causes of aneurysm included atherosclerosis (12 cases), fibromuscular dysplasia (eight cases), a congenital defect (five cases), infection (one case), and trauma (six cases); in six cases aneurysm was secondary to spontaneous dissection.

[Floating thrombus in the right atrium and severe pulmonary embolism. Value of intravenous thrombolysis].

Mobile right atrial thrombi carry a high risk of pulmonary embolism which may be massive and are a medical emergency. Although surgery is commonly indicated, treatment with intravenous thrombolytics is an alternative and was successful in 4 out of 6 cases reported by the authors. Six patients, admitted for severe pulmonary embolism confirmed by pulmonary scintigraphy (6 cases) and by angiography (2 cases), underwent echocardiography which demonstrated a mobile right atrial thrombus.

False aneurysm of the ascending aorta following aortic valve replacement.

False aneurysm of the ascending aorta is a rare and life-threatening complication of open heart surgery, usually occurring late after operation. Echocardiography, especially transesophageal echocardiography, is a non-invasive method of examination which can be very helpful in its diagnosis. Deep hypothermia and circulatory arrest allow a bloodless field during surgery and provide an adequate patient protection.

Adult coronary aneurysms related to Kawasaki disease.

Kawasaki disease (KD) is an acute illness encountered in infancy and childhood. Cardiovascular complications of this syndrome are recognized as being part of the adult coronary artery disease population. Reported herein is the surgical treatment of multiple coronary artery aneurysms, severe stenotic lesions and thrombotic involvement of the coronary arterial tree that could be ascribed to childhood KD in two adult patients with no risk factors for atherosclerotic heart disease.

Fibromuscular dysplasia of the internal carotid artery: long-term surgical results.

Fifty-eight patients underwent 72 operations for symptomatic fibromuscular dysplasia (FMD) between 1970 and 1986. There were 35 females and 23 males aged between 36 and 76 years (average 56). Among the 72 operated on lesions (11 bilateral) FMD stenotic lesions (string of beads, tubular, focal) were isolated (32) or associated with elongation (tortuosity, coiling, kink) in 24 cases, FDM aneurysms (7), and dissecting pseudoaneurysms (9).

Mediastinitis in heart transplant recipients: successful treatment by closed local irrigation.

Following cardiac transplantation bacterial mediastinitis is a severe early complication. Between March 1986 and September 1993, cardiac transplant operations were performed in 101 patients, of whom six developed purulent mediastinitis. Treatment consisted of surgical débridement, closed local irrigation, drainage and systemic antibiotics.

Heart transplantation for terminal congestive heart failure in an acromegalic patient.

Dilated hypokinetic cardiomyopathy in an acromegalic patient is an uncommon event. Specific hormonal therapy with octreotide (a somatostatin analogue) is now recognized as able to improve cardiac failure. A case of worsening of cardiac function under such a therapy is described in this report.

Doppler echocardiographic evaluation of the Omnicarbon cardiac valve prostheses.

Comprehensive 2 D/Doppler examination of 98 patients (mean age 56), implanted between September 1984 and February 1991, with normally functioning aortic (n = 49) and mitral (n = 49) Omnicarbon valves (OC) were analyzed in order to characterize the normal hemodynamic profiles of the OC valves. The mean time from implantation was 36.4 months (range 6 to 78).

[Dilated cardiomyopathy in acromegaly worsening under octreotide treatment. Apropos of a case].

Dilated cardiomyopathy associated with acromegaly is rare, but may improve with octreotide, a somatostatin analogue. The authors give the first description here of paradoxical worsening in cardiac function during such treatment, with the onset of episodes of acute decompensation following each attempt at starting treatment. Thus worsening was confirmed objectively by a challenge test with octreotide: increased dyspnea, fall in shortening fraction and in echocardiographic cardiac output (of 17 to 14% and 4 to 3 l/min respectively), a decrease in isotopic ejection fraction from 15 to 6% and this in parallel with efficacy regarding hormone levels of GH and IGF1 and a reduction in tumour size by CT scan.

Superior mesenteric arteriovenous fistula after ileal resection.

Postoperative superior mesenteric arteriovenous fistula is very rare. We report the case of a 55-year-old woman in whom the discovery of an abdominal bruit led to the diagnosis of superior mesenteric arteriovenous fistula seven years after ileal resection. The clinical and pathophysiological aspects, as well as the therapeutic modalities, of this rare lesion are reviewed.