Age-related changes in sleep spindles characteristics during daytime recovery following a 25-hour sleep deprivation.

OBJECTIVES: The mechanisms underlying sleep spindles (~11-15 Hz; >0.5 s) help to protect sleep. With age, it becomes increasingly difficult to maintain sleep at a challenging time (e.g., daytime), even after sleep loss. This study compared spindle characteristics during daytime recovery and nocturnal sleep in young and middle-aged adults. In addition, we explored whether spindles characteristics in baseline nocturnal sleep were associated with the ability to maintain sleep during daytime recovery periods in both age groups. METHODS: Twenty-nine young (15 women and 14 men; 27.3 y ± 5.0) and 31 middle-aged (19 women and 13 men; 51.6 y ± 5.1) healthy subjects participated in a baseline nocturnal sleep and a daytime recovery sleep after 25 hours of sleep deprivation. Spindles were detected on artifact-free Non-rapid eye movement (NREM) sleep epochs. Spindle density (nb/min), amplitude (µV), frequency (Hz), and duration (s) were analyzed on parasagittal (linked-ears) derivations. RESULTS: In young subjects, spindle frequency increased during daytime recovery sleep as compared to baseline nocturnal sleep in all derivations, whereas middle-aged subjects showed spindle frequency enhancement only in the prefrontal derivation. No other significant interaction between age group and sleep condition was observed. Spindle density for all derivations and centro-occipital spindle amplitude decreased whereas prefrontal spindle amplitude increased from baseline to daytime recovery sleep in both age groups. Finally, no significant correlation was found between spindle characteristics during baseline nocturnal sleep and the marked reduction in sleep efficiency during daytime recovery sleep in both young and middle-aged subjects. CONCLUSION: These results suggest that the interaction between homeostatic and circadian pressure modulates spindle frequency differently in aging. Spindle characteristics do not seem to be linked with the ability to maintain daytime recovery sleep.

Fast and slow spindle involvement in the consolidation of a new motor sequence.

This study aimed to determine the distinct contribution of slow (11-13 Hz) and fast (13-15 Hz) spindles in the consolidation process of a motor sequence learning task (MSL). Young subjects (n = 12) were trained on both a finger MSL task and a control (CTRL) condition, which were administered one week apart in a counterbalanced order. Subjects were asked to practice the MSL or CTRL task in the evening (approximately 9:00 p.m.) and their performance was retested on the same task 12h later (approximately 9:00 a.m.). Polysomnographic (PSG) recordings were performed during the night following training on either task, and an automatic algorithm was used to detect fast and slow spindles and to quantify their characteristics (i.e., density, amplitude, and duration). Statistical analyses revealed higher fast (but not slow) spindle density after training on the MSL than after practice of the CTRL task. The increase in fast spindle density on the MSL task correlated positively with overnight performance gains on the MSL task and with difference in performance gain between the MSL and CTRL tasks. Together, these results suggest that fast sleep spindles help activate the cerebral network involved in overnight MSL consolidation, while slow spindles do not appear to play a role in this mnemonic process.

[Anatomy of the liver: what you need to know]. / Anatomie du foie: ce qu'il faut savoir.

A precise knowledge of arterial, portal, hepatic and biliary anatomical variations is mandatory when a liver intervention is planned. However, only certain variations must be searched when a precise intervention is planned. The basic liver anatomy as well as the most relevant malformations will be precised.

Froude number fractions to increase walking pattern dynamic similarities: application to plantar pressure study in healthy subjects.

The purpose of this study was to determine if using similar walking velocities obtained from fractions of the Froude number (N(Fr)) and leg length can lead to kinematic and kinetic similarities and lower variability. Fifteen male subjects walked on a treadmill at 0.83 (VS(1)) and 1.16ms(-1) (VS(2)) and then at two similar velocities (V(Sim27) and V(Sim37)) determined from two fractions of the N(Fr) (0.27 and 0.37) so that the average group velocity remained unchanged in both conditions (VS(1)=V (Sim27)andVS(2)=V (Sim37)). N(Fr) can theoretically be used to determine walking velocities proportional to leg lengths and to establish dynamic similarities between subjects. This study represents the first attempt at using this approach to examine plantar pressure. The ankle and knee joint angles were studied in the sagittal plane and the plantar pressure distribution was assessed with an in-shoe measurement device. The similarity ratios were computed from anthropometric parameters and plantar pressure peaks. Dynamically similar conditions caused a 25% reduction in leg joint angles variation and a 10% significant decrease in dimensionless pressure peak variability on average of five footprint locations. It also lead to heel and under-midfoot pressure peaks proportional to body mass and to an increase in the number of under-forefoot plantar pressure peaks proportional to body mass and/or leg length. The use of walking velocities derived from N(Fr) allows kinematic and plantar pressure similarities between subjects to be observed and leads to a lower inter-subject variability. In-shoe pressure measurements have proven to be valuable for the understanding of lower extremity function. Set walking velocities used for clinical assessment mask the effects of body size and individual gait mechanics. The anthropometric scaling of walking velocities (fraction of N(Fr)) should improve identification of unique walking strategies and pathological foot functions.

Usefulness of transjugular intrahepatic portosystemic shunt in the management of bleeding ectopic varices in cirrhotic patients.

PURPOSE: To evaluate the safety and efficacy of transjugular intrahepatic portosystemic shunt (TIPS) in the control of bleeding from ectopic varices. METHODS: From 1995 to 2004, 24 cirrhotic patients, bleeding from ectopic varices, mean age 54.5 years (range 15-76 years), were treated by TIPS. The etiology of cirrhosis was alcoholic in 13 patients and nonalcoholic in 11 patients. The location of the varices was duodenal (n = 5), stomal (n = 8), ileocolic (n = 6), anorectal (n = 3), umbilical (n = 1), and peritoneal (n = 1). RESULTS: TIPS controlled the bleeding in all patients and induced a decrease in the portacaval gradient from 19.7 +/- 5.4 to 6.4 +/- 3.1 mmHg. Postoperative complications included self-limited intra-abdominal bleeding (n = 2), self-limited hemobilia (n = 1), acute thrombosis of the shunt (n = 1), and bile leak treated by a covered stent (n = 1). Median follow-up was 592 days (range 28-2482 days). Rebleeding occurred in 6 patients. In 2 cases rebleeding was observed despite a post-TIPS portacaval gradient lower than 12 mmHg and was controlled by variceal embolization; 1 patient underwent surgical portacaval shunt and never rebled; in 3 patients rebleeding was related to TIPS stenosis and treated with shunt dilatation with addition of a new stent. The cumulative rate of rebleeding was 23% and 31% at 1 and 2 years, respectively. One- and 2-year survival rates were 80% and 76%, respectively. CONCLUSION: The present series demonstrates that bleeding from ectopic varices, a challenging clinical problem, can be managed safely by TIPS placement with low rebleeding and good survival rates.

Clinical and cardiorespiratory effects of propofol in the spotted bamboo shark (Chylloscyllium plagiosum).

Sharks are important exhibit animals in aquariums and zoologic institutions worldwide. Although veterinarians are encountering these species more frequently in these institutions, our knowledge regarding safe restraint and anesthesia is limited. To date there have been only a few anecdotal reports or studies evaluating the effects of tricaine methane sulfonate (MS-222), ketamine hydrochloride, and tiletamine and zolazepam (Telazol) in sharks. The purpose of this study was to evaluate the clinical and cardiorespiratory effects of propofol in spotted bamboo sharks (Chylloscyllium plagiosum). Nine wild-caught adult female spotted bamboo sharks (mean weight 2.4 kg+/-SD 1.45 kg) were used in this study. Propofol (2.5 mg/kg) was administered over 30 sec via the caudal tail vein. Heart rate, respiratory rate, time to relaxation, escape response, loss of righting reflex, and response to noxious stimuli (fin pinch) were evaluated and recorded at baseline and 5, 10, 15, 30, 45, 60, and 75 min after propofol administration. A surgical plane of anesthesia was achieved when the shark lost its righting reflex, did not respond to noxious painful stimuli, and no longer resisted handling. The righting reflex was lost within 5 min of propofol administration, and a surgical plane of anesthesia was observed in all nine sharks. Heart rate (P = 0.5) and respiratory rate (P = 0.5) did not change significantly over time. The righting response returned within 60 min in 44% (4/9) of the sharks, 75 min in 22% (2/ 9) of the sharks, and over 200 min in 33% (3/9) of the sharks. All nine animals recovered uneventfully. Propofol provided a safe anesthetic event for spotted bamboo sharks.

Assessment and conservation of the giant gomeran lizard (Gallotia bravoana).

In June 1999, a species of lizard previously considered extinct was rediscovered on the island of La Gomera, Spain. The giant gomeran lizard, Gallotia bravoana, is highly endangered and at risk of extinction by the feral cat population. A conservation effort to save the species was initiatived by the regional and central Spanish government and six lizards were captured and brought into captivity. This paper describes the results of the initial assessment of the health of the animals, by a physical examination and by haematological, biochemical, radiographical and coprological investigations. The methods used to maintain the animals in captivity are described and the first captive breeding success is reported.

[Liver anatomy: echography and Doppler]. / Anatomie du foie: échographie et Doppler.

Ultrasonography is an excellent tool for the study of the anatomy of the human liver. This article shows, with the help of sonographic views along the long axis of portal and hepatic veins, and the different landmarks of the liver, how to delineate the eight segments of the liver. Doppler examination allows indentification of the portal veins and the hepatic arteries in the portal triad.

Relationship between pre-TIPS liver perfusion by the portal vein and the incidence of post-TIPS chronic hepatic encephalopathy.

OBJECTIVE: In the present study we evaluated the predictive value of pretransjugular intrahepatic portosystemic shunt (TIPS) portal perfusion as assessed by Doppler ultrasonography for the onset of chronic encephalopathy after TIPS. METHODS: A total of 231 cirrhotic patients were followed-up prospectively after TIPS placement. The pattern of intrahepatic portal flow was assessed before TIPS. Patients were divided into two groups according to Doppler findings. Group 1 comprised patients with prograde portal flow (n = 200), whereas group 2 comprised those with loss of portal perfusion (hepatofugal or back-and-forth flow or portal vein thrombosis; n = 31). The presence of chronic encephalopathy during a median follow-up of 32 months was prospectively recorded. The prognostic value of the following parameters for the onset of chronic recurrent encephalopathy after TIPS was evaluated: age, presence of encephalopathy before TIPS, alcoholism, Pugh score, and loss of portal perfusion before TIPS. The independent prognostic value of each variable was tested with a multiple logistic regression analysis. RESULTS: The two groups were comparable in terms of age, incidence of prior episodes of hepatic encephalopathy, and portacaval gradient before and after the procedure; however, liver failure was more severe in patients in group 2 (Pugh score: 9.2 +/- 1.9 vs 10.3 +/- 1.7). The 3-yr survival was identical for both groups; 25% of the 200 patients in group 1 developed chronic encephalopathy as compared to 6% of the 31 patients in group 2 (p = 0.03). Multiple logistic regression analysis demonstrated that loss of portal perfusion and age >65 yr were the only independent predictors of the onset of post-TIPS chronic encephalopathy (odds ratios 0.24 and 1.98, respectively). CONCLUSIONS: Cirrhotic patients with loss of portal perfusion before TIPS were protected against post-TIPS chronic hepatic encephalopathy despite a more severe liver dysfunction at baseline. The only other independent predictive factor for the onset of this complication was age.

Transjugular intrahepatic portosystemic shunt (TIPS) versus endoscopic variceal ligation in the prevention of variceal rebleeding in patients with cirrhosis: a randomised trial.

BACKGROUND AND AIMS: The transjugular intrahepatic portosystemic shunt (TIPS) is a new therapeutic modality for variceal bleeding. In this study we compared the two year survival and rebleeding rates in cirrhotic patients treated by either variceal band ligation or TIPS for variceal bleeding. METHODS: Eighty cirrhotic patients (Pugh score 7-12) with variceal bleeding were randomly allocated to TIPS (n=41) or ligation (n=39), 24 hours after control of bleeding. RESULTS: Mean follow up was 581 days in the ligation group and 678 days in the TIPS group. The two year survival rate was 57% in the TIPS group and 56% in the ligation group (NS); the incidence of variceal rebleeding after two years was 18% in the TIPS group and 66% in the ligation group (p<0.001). Uncontrolled rebleeding occurred in 11 patients in the ligation group (eight were rescued by emergency TIPS) but in none of the TIPS group. The incidence of encephalopathy at two years was 47% in the TIPS group and 44% in the ligation group (NS). CONCLUSIONS: TIPS did not increase the two year survival rate compared with variceal band ligation after variceal bleeding in cirrhotic patients with moderate or severe liver failure. It significantly reduced the incidence of variceal rebleeding without increasing the rate of encephalopathy.

Extraarticular snapping hip: sonographic findings.

OBJECTIVE: The aim of the study was to determine the sonographic findings of snapping hip and to correlate the findings with the presence or absence of pain. MATERIALS AND METHODS: Twenty patients with snapping hip were examined with sonography. Conventional and dynamic sonographic examinations of both hips were performed using a 5.0- or 7.0-MHz transducer. RESULTS: Conventional sonographic studies allowed identification of various structural abnormalities (tendinitis, bursitis, synovitis) and helped to document tenderness along the course of specific tendons. Dynamic sonographic studies revealed 26 cases of snapping hip. In 24 of these 26 cases, the underlying cause was clearly identified. Twenty-two snapping hips were caused by an abnormal movement of the iliopsoas tendon, and two were caused by iliotibial band friction over the greater trochanter. One patient reported a bilateral snapping sensation that could not be documented on sonography. Snapping hip was elicited by a wide variety of hip movements. Sonography established an immediate temporal correlation between the jerky tendon motion and the painful snap reported by the patient. Only 14 cases of snapping hip were painful. CONCLUSION: Conventional sonographic studies can identify signs of tendinitis, bursitis, or synovitis. Dynamic sonographic studies revealed the cause of snapping hip in most patients. Snapping hip is characterized on sonography by a sudden abnormal displacement of the snapping structure. In our study, a significant proportion of the cases of snapping hip were not painful.

Predictors of clinical response to transjugular intrahepatic portosystemic shunt (TIPS) in cirrhotic patients with refractory ascites.

OBJECTIVE: Transjugular intrahepatic portosystemic shunt (TIPS) is used increasingly as a treatment for refractory ascites. The aim of the present study was to determine the prognostic value of different parameters in predicting a favorable evolution following TIPS in a cohort of 53 cirrhotic patients without organic renal disease and with refractory ascites. METHODS: Patients were classified as good responders if they survived more than 6 months, without severe chronic hepatic encephalopathy and with good control of ascites. The prognostic value for a good outcome was evaluated using age, creatinine clearance, plasma renin activity, plasma aldosterone, and Pugh score. RESULTS: Good control of ascites was obtained in 90%. The cumulative survival rate was 54% at 6 months, 48% at 1 yr, and 39% at 2 yr. The vast majority of patients died of complications of hepatic insufficiency. Severe chronic hepatic encephalopathy developed in 26%. Overall, a good clinical response was observed in 47%. Creatinine clearance was identified as the only pre-TIPS factor to be significantly and independently associated with a good clinical response to TIPS for refractory ascites. A good clinical response was observed in 57% of patients with a creatinine clearance >36 ml/min compared to 9% of those with a clearance <36 ml/min (p < 0.01). This cutoff point in creatinine clearance had a sensitivity of 96% and a specificity of 36%; positive predictive and negative predictive values were 57% and 90%, respectively. CONCLUSIONS: TIPS might be useful for the treatment of refractory ascites in cirrhotic patients without severe renal function impairment. However, the TIPS usefulness still has to be demonstrated compared to large volume paracentesis or Leveen shunt. In patients with poor renal function or with liver failure after TIPS, liver transplantation should be considered.

The kidney in children with tyrosinemia: sonographic, CT and biochemical findings.

BACKGROUND: Tyrosinemia relates to a deficiency of fumarylacetoacetate hydrolase and presents early in life with central nervous system and liver abnormalities. Renal function is often impaired. Little is known about the architecture and function of the kidneys. OBJECTIVE: Imaging changes on US and CT are compared to the function of the kidneys in children with tyrosinemia, and followed after liver transplantation. MATERIALS AND METHODS: Renal sonography, CT and renal function tests in 32 children were reviewed. Renal length, volume, echogenicity and nephrocalcinosis were evaluated. Renal function was assessed by glomerular filtration rate, and the presence of aminoaciduria, acidosis and calciuria. Seventeen children had open renal biopsy during time of liver transplantation. Histology was reviewed. Statistical analyses relating renal structure to function were performed, and repeated after transplantation. RESULTS: The kidneys were enlarged (47 %), hyperechogenic (47 %) and showed nephrocalcinosis (16 %). There was delayed excretion of contrast medium at CT in 64 %. Aminoaciduria was present in 82 % of children, hypercalciuria in 67 %, tubular acidosis in 59 %, and low GFR in 48 %. Delayed excretion of contrast was associated with low GFR (P < 0.05). Renal biopsies showed dilated tubules (81 %), interstitial fibrosis (56 %), glomerulosclerosis (56 %) and tubular atrophy (56 %). During a mean observation period of 3 years following liver transplantation, GFR improved in 50 %, tubular acidosis in 50 % and hypercalciuria in 70 %. No change was noted in renal size or sonographic architecture. CONCLUSION: Renal architecture and function are abnormal in the majority of children with tyrosinemia. Liver transplantation improves renal function in about 50 % of patients, but abnormal renal size and architecture persist.

[Role of transcranial ultrasonography in neuroradiological diagnosis]. / Le rôle de l'écho-Doppler transcrânien en neuroradiologie diagnostique.

Blood flow within the major arteries supplying the brain can be studied with transcranial Doppler sonography, a noninvasive, portable procedure. We describe the technique of examination, as well as indications in children and adults such as the investigation of intracranial stenosis, collateral pathways, vasospasm, cerebral emboli and arteriovenous malformations.

Thickening of the wall of the bile duct due to intramural collaterals in three patients with portal vein thrombosis.

OBJECTIVE: We report three cases of a rare form of cavernoma developed within the wall of the common bile duct. CONCLUSION: To our knowledge, this kind of portal cavernoma has not been described in the literature. Because the cavernoma may be easily confused with other causes of bile duct wall thickening, color Doppler sonography is mandatory for a correct diagnosis.