Automatic correction of intensity inhomogeneities improves unsupervised assessment of abdominal fat by MRI

PURPOSE: To demonstrate that unsupervised assessment of abdominal adipose tissue distribution by magnetic resonance imaging (MRI) can be improved by integrating automatic correction of signal inhomogeneities. MATERIALS AND METHODS: Twenty subjects (body mass index [BMI] 23.7-44.0 kg/m(2)) underwent abdominal (32 slices) MR imaging with a 1.9T Elscint Prestige scanner. Many images were affected by relevant intensity distortions. Unsupervised segmentation of subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) was performed by a previously validated algorithm exploiting standard fuzzy clustering segmentation. Images were also processed by an improved version of the software, including automatic correction of intensity inhomogeneities. To assess the effectiveness of the two methods SAT and VAT volumes were compared with manual analysis performed by a trained operator. RESULTS: Coefficient of variation between manual and unsupervised analysis was significantly improved by inhomogeneities correction in SAT evaluation. Systematic underestimation of SAT was also corrected. A less important performance improvement was found in VAT measurement. CONCLUSION: The results of this study suggest that the compensation of signal inhomogeneities greatly improves the effectiveness of the unsupervised assessment of abdominal fat. Correction of intensity distortions is important in SAT evaluation and less significant in VAT measurement.     

Evaluation of the use of a biodegradable ureteral stent after retrograde endopyelotomy in a porcine model

PURPOSE: We evaluated the use of a poly-L-lactide-co-glycolide (PLGA) bioabsorbable ureteral stent after Acucise balloon incision (Applied Medical Resources, Rancho Santa Magarita, California) endopyelotomy in a porcine model. MATERIALS AND METHODS: After unilateral Acucise endopyelotomy in 9 female Yucatan minipigs a self-reinforced PLGA stent was placed in 5 (group 1) and a 7Fr double pigtail Percuflex stent (Boston Scientific, Natick, Massachusetts) was placed in 4 (group 2). Preoperatively, and 6 and 12 weeks postoperatively plain x-ray of the kidneys, ureters and bladder, cystography, side specific creatinine clearance and retrograde ureterography were done. The contralateral ureters served as untreated controls. The 7Fr stents were removed at 6 weeks. All animals were sacrificed at 12 weeks after bilateral flow studies. Histological specimens from 4 sites along the urinary tract were graded on a healing score of 0-normal, to 3-severe changes. RESULTS: Side specific creatinine clearance was similar to preoperative values at 6 and 12 weeks. At the 2 time points plain x-ray of the kidneys, ureters and bladder in group 1 showed retroperitoneal stent fragments in 3 of the 5 animals, which was confirmed at autopsy. Retrograde ureterography in group 1 showed mild hydronephrosis in all 5 ureters and saccular diverticula in 4, which was similar in 2 and 3 animals, respectively, in group 2. Cystography demonstrated grades 1 to 2 reflux in 2 animals at 6 weeks but none at 12 weeks in group 1 and no reflux at either time point in group 2. Flow rates and healing scores were statistically similar in the 2 groups but the latter trended toward less favorable healing of ureteral musculature with application of the absorbable stent. CONCLUSIONS: In this pilot study the use of self-reinforced PLGA biodegradable ureteral stents was feasible after Acucise endopyelotomy in a porcine model with radiographic and fluid flow results that were relatively similar to those of standard 7Fr stents but with less favorable biocompatibility.     

Microinjection of an Adenosine A1 Agonist into the Medial Pontine Reticular Formation Increases Tail Flick Latency to Thermal Stimulation

Background: Both pain and the pharmacologic management of pain can cause the undesirable effect of sleep disruption. One goal of basic and clinical neuroscience is to facilitate rational drug development by identifying the brain regions and neurochemical modulators of sleep and pain. Adenosine is thought to be an endogenous sleep promoting substance and adenosinergic compounds can contribute to pain management. In the pontine brain stem adenosine promotes sleep but the effects of pontine adenosine on pain have not been studied. This study tested the hypothesis that an adenosine agonist would cause antinociception when microinjected into pontine reticular formation regions that regulate sleep.

Methods: The tail flick latency (TFL) test quantified the time in seconds for an animal to move its tail away from a thermal stimulus created by a beam of light. TFL measures were used to evaluate the antinociceptive effects of the adenosine A1 receptor agonist N6-p-sulfophenyladenosine (SPA). Pontine microinjection of SPA (0.1 [mu]g/0.25 [mu]l, 0.88 mm) was followed by TFL measures as a function of time after drug delivery and across the sleep-wake cycle.

Results: Compared with saline (control), pontine administration of the adenosine agonist significantly increased latency to tail withdrawal (P < 0.0001). The increase in antinociceptive behavior evoked by the adenosine agonist SPA was blocked by pretreatment with the adenosine A1 receptor antagonist 8-cyclopentyl-1, 3-dipropylxanthine (DPCPX, 0.75 ng/0.25 [mu]l, 10 [mu]m).     

Long-term followup after laparoscopic radical nephrectomy

PURPOSE: Laparoscopic radical nephrectomy has been shown to be less morbid than traditional open radical nephrectomy. The long-term oncological effectiveness of laparoscopic radical nephrectomy remains to be established. MATERIALS AND METHODS: At 3 centers patients undergoing laparoscopic radical nephrectomy before November 1, 1996 with pathologically confirmed renal cell carcinoma were identified. A representative group of patients undergoing open radical nephrectomy for clinical T1, T2 lesions was also identified. Staging, operative details and postoperative course were reviewed. Followup consisted of review of clinical, laboratory and radiological records. Kaplan-Meier analysis was performed. RESULTS: The study included 64 patients treated with laparoscopic and 69 treated with open radical nephrectomy with respective average ages of 60.6 and 61.3 years at surgery. On preoperative imaging open lesions were larger (6.2 cm., range 2.5 to 15) than laparoscopic radical nephrectomy lesions (4.3 cm., range 2 to 10, p <0.001). Pathology reports revealed no difference in specimen weight (425 and 495 gm., p = 0.146) or average Fuhrman grade (1.88 and 1.78, p = 0.476) between laparoscopic and open radical nephrectomy, respectively. Median followup was 54 months (range 0 to 94) for laparoscopic and 69 months (range 8 to 114) for open radical nephrectomy. Kaplan-Meier analysis with log rank comparison revealed 5-year recurrence-free survival of 92% and 91% for laparoscopic and open radical nephrectomy, respectively (p = 0.583). At 5 years cancer specific survival was 98% and 92% (p = 0.124), and nonspecific survival was 81% and 89% (p = 0.260) for laparoscopic and open radical nephrectomy, respectively. CONCLUSIONS: Laparoscopic radical nephrectomy confers long-term oncological effectiveness equivalent to traditional open radical nephrectomy.     

Successful late reintervention after the arterial switch procedure

BACKGROUND: The arterial switch operation is the therapy of choice for transposition of the great arteries. METHODS: A retrospective analysis of all children undergoing the arterial switch operation between November 1985 and October 2000 was conducted, highlighting the frequency and nature of late invasive reintervention. RESULTS: One hundred forty-four children were operated on. Operative survival was 89% (128 of 144). Late reintervention was required in 23% (29 of 128) of survivors. Neopulmonary stenosis (PS) was the most common complication requiring treatment, occurring in 16% (21 of 128) of patients. Eleven of 21 patients with PS required reoperation, whereas 10 were managed with percutaneous techniques. Other indications for reintervention included aortic arch obstruction (3 patients), ventricular septal defect (with PS in 2 patients), bronchial stenosis (2 patients), coronary stenosis (2 patients), aortic stenosis (with PS in 1 patient), and residual atrial septal defect (1 patient). There has been no mortality or major morbidity in those children who have undergone reintervention. CONCLUSIONS: Invasive reintervention after the arterial switch operation is occasionally required. The most common indication is PS. Reintervention is well tolerated by those children who require it. Continued follow-up for late complications is required in this patient population.     

CD4+CD25+FoxP3+ T lymphocytes fail to suppress myelin basic protein-induced proliferation in patients with multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disorder directed against self antigens of the central nervous system. CD4⁺CD25⁺FoxP3⁺ regulatory T cell (T_reg) mediated suppression is an essential mechanism of self-tolerance. We studied whether changes in the suppressive function of a mixture of CD25^high and CD25^intemediate expressing T_reg cells in myelin basic protein (MBP)-induced proliferation occurred in untreated MS patients. Suppression of MBP-induced proliferation was observed in 13 out of 29 (45%) MS patients; this was significantly (p < 0.05) less compared with 17 out of 19 (89%) healthy individuals. Relative T_reg counts was significantly increased in MS patients (mean ± S.D.; 20 ± 8%) compared with healthy individuals (15 ± 5%). These findings suggest that impaired T_reg function may be involved in pathogenesis of MS.     

Predictors of marijuana use in adolescents before and after licit drug use: examination of the gateway hypothesis

OBJECTIVE: The authors investigated whether the transition from licit drug use to marijuana use is determined by particular risk factors, as specified by the gateway hypothesis. They also evaluated the accuracy of the "gateway sequence" (illicit drug use following licit drugs) for predicting a diagnosis of substance use disorder. METHOD: Boys who consumed licit drugs only (N=99), boys who consumed licit drugs and then transitioned to marijuana use (gateway sequence) (N=97), and boys who used marijuana before using licit substances (alternative sequence) (N=28) were prospectively studied from ages 10-12 years through 22 years to determine whether specific factors were associated with each drug use pattern. The groups were compared on 35 variables measuring psychological, family, peer, school, and neighborhood characteristics. In addition, the utility of the gateway and alternative sequences in predicting substance use disorder was compared to assess their clinical informativeness. RESULTS: Twenty-eight (22.4%) of the participants who used marijuana did not exhibit the gateway sequence, thereby demonstrating that this pattern is not invariant in drug-using youths. Among youths who did exhibit the gateway pattern, only delinquency was more strongly related to marijuana use than licit drug use. Specific risk factors associated with transition from licit to illicit drugs were not revealed. The alternative sequence had the same accuracy for predicting substance use disorder as the gateway sequence. CONCLUSIONS: Proneness to deviancy and drug availability in the neighborhood promote marijuana use. These findings support the common liability model of substance use behavior and substance use disorder.     

Unlocking the nature of the phonological-deep dyslexia continuum: the keys to reading aloud are in phonology and semantics

It has been argued that normal reading and acquired dyslexias reflect the role of three underlying primary systems (phonology, semantics, and vision) rather than neural mechanisms dedicated to reading. This proposal is potentially consistent with the suggestion that phonological and deep dyslexia represent variants of a single reading disorder rather than two separate entities. The current study explored this possibility, the nature of any continuum between the disorders, and the possible underlying bases of it. A case series of patients were given an assessment battery to test for the characteristics of phonological and deep dyslexia. The status of their underlying phonological and semantic systems was also investigated. The majority of participants exhibited many of the symptoms associated with deep dyslexia whether or not they made semantic errors. Despite wide variation in word and nonword reading accuracy, there was considerable symptom overlap across the cohort and, thus, no sensible dividing line to separate the participants into distinct groups. The patient data indicated that the deep-phonological continuum might best be characterized according to the severity of the individual's reading impairment rather than in terms of a strict symptom succession. Assessments of phonological and semantic impairments suggested that the integrity of these primary systems underpinned the patients' reading performance. This proposal was supported by eliciting the symptoms of deep-phonological dyslexia in nonreading tasks.     

Radiologic and Endoscopic Evaluation for Laparoscopic Adjustable Gastric Banding: Preoperative and Follow-Up

Background: Laparoscopic adjustable silicone gastric banding (LASGB) has replaced vertical banded gastroplasty (VBG) as the most widespread restrictive bariatric operation in Europe. Although these two procedures are similar in principle, the experience concerning the preoperative examinations and follow-up cannot be arbitrarily transferred from VBG to LASGB.The reasons for and consequences drawn from radiologic and endoscopic examinations are described. Methods: From December 1996 to January 2000, 148 patients (84% women, average age 39 years, body weight 127 kg, BMI 45 kg/m²) underwent LASGB. The mean follow-up was 17 months. Upper GI series, abdominal ultrasound, and gastroscopy were done before operation. The postoperative stoma adjustments were performed under radiological observation. All adjustments were analyzed. Results: Preoperative: Of 147 upper GI series, 74 showed hiatal hernia, 2 motility disorders, and 1 an incomplete malrotation. In 104 gastroscopies, 35 reflux and 53 gastritis with 24 Helicobacter pylori infections were found. Postoperative: On average, 2.7 radiological adjustments were done per patient. Until satisfactory satiety and weight reduction, 78% of the patients needed 0-3 adjustments. Besides routine adjustments, an additional 57 upper GI series were done in 35 patients, 44 times with opening of the stoma-diameter. A total of 14 slippages and 4 pouch enlargements were found. A gastroscopy was required in 12 patients. Conclusion: Radiologic and endoscopic examinations before LASGB revealed pathology needing therapy in 42% of the patients and provided important additional information influencing the operative procedure. At an average follow-up of 17 months, 24% of the 148 patients needed unplanned additional upper GI series.