Spectroscopic imaging of the pilocarpine model of human epilepsy suggests that early NAA reduction predicts epilepsy.

Reduced hippocampal N-acetyl aspartate (NAA) is commonly observed in patients with advanced, chronic temporal lobe epilepsy (TLE). It is unclear, however, whether an NAA deficit is also present during the clinically quiescent latent period that characterizes early TLE. This question has important implications for the use of MR spectroscopic imaging (MRSI) in the early identification of patients at risk for TLE. To determine whether NAA is diminished during the latent period, we obtained high-resolution (1)H spectroscopic imaging during the latent period of the rat pilocarpine model of human TLE. We used actively detuneable surface reception and volume transmission coils to enhance sensitivity and a semiautomated voxel shifting method to accurately position voxels within the hippocampi. During the latent period, 2 and 7 d following pilocarpine treatment, hippocampal NAA was significantly reduced by 27.5 +/- 6.9% (P < 0.001) and 17.3 +/- 6.9% (P < 0.001) at 2 and 7 d, respectively. Quantitative estimates of neuronal loss at 7 d (2.3 +/- 7.7% reduction; P = 0.58, not significant) demonstrate that the NAA deficit is not due to neuron loss and therefore likely represents metabolic impairment of hippocampal neurons during the latent phase. Therefore, spectroscopic imaging provides an early marker for metabolic dysfunction in this model of TLE.     

Patellar prosthesis positioning in total knee arthroplasty. A roentgenographic study

Patellar prosthesis positioning in 40 primary total knee replacements was evaluated with regard to (1) patellar tilt, (2) angle between the patellar component and patellar bony remnant, (3) lateral versus medial placement, (4) patellar height, and (5) size of the patellar component versus patellar length. Two different designs were evaluated. Twenty knees that were resurfaced with a patellar button prosthesis and implanted with conventional surgical technique constituted Group A. Twenty knees that were resurfaced with a new biconvex prosthesis and implanted with specially designed instrumentation constituted Group B. For Group A, the patellar tilt averaged 4.25 degrees preoperative and 8.35 degrees postoperative. For Group B the patellar tilt averaged 4.60 degrees preoperative and 1.83 degrees postoperative. In Group B, there was significant improvement in patellar position, with only two patients showing values exceeding the neutral range (p = 0.0409). The angle between the patellar component and the bony remnant in Group A averaged 5.975 degrees, and in Group B, 1.447 degrees. Two patients in Group A and 18 patients in Group B had values in the normal range for patellar tilt and the angle between the prosthesis and the bone. The prosthesis was inserted medial to the patellar center in six patients in Group A and one patient in Group B. A significant decrease in patellar height was noted for both groups, but values were still within the normal range. Both groups showed significant increase in the postoperative articular length, indicating that oversized prostheses were inserted and excess bone removed.     

Characteristics of Hidden Status Among Users of Crack, Powder Cocaine, and Heroin in Central Harlem

This article analyzes hidden status among crack, powder cocaine, and heroin users and setters, in contrast to more accessible users/sellers. Several sampling strategies acquired 657 users (N=559) and sellers (N=98). Indicators of hidden status were those who (1) paid rent in full in the last 30 days, (2) used nonstreet drug procurement. (3) had legal jobs, and (4) earned $1,000 or more in legal income in the last 30 days. Nearly half had at least one indicator: approximately 16% of users/sellers had two to four indicators. In logistic regression analyses, those who had not panhandled in the last 30 days, those who had used powder cocaine in the last 30 days, and those never arrested were the most likely to have hidden status, whether the analysis predicted those having any indicators or those having two to four indicators. The four indicators begin to operationally define hidden status among users of cocaine and heroin.     

A framework for evaluating image segmentation algorithms.

The purpose of this paper is to describe a framework for evaluating image segmentation algorithms. Image segmentation consists of object recognition and delineation. For evaluating segmentation methods, three factors-precision (reliability), accuracy (validity), and efficiency (viability)-need to be considered for both recognition and delineation. To assess precision, we need to choose a figure of merit, repeat segmentation considering all sources of variation, and determine variations in figure of merit via statistical analysis. It is impossible usually to establish true segmentation. Hence, to assess accuracy, we need to choose a surrogate of true segmentation and proceed as for precision. In determining accuracy, it may be important to consider different 'landmark' areas of the structure to be segmented depending on the application. To assess efficiency, both the computational and the user time required for algorithm training and for algorithm execution should be measured and analyzed. Precision, accuracy, and efficiency factors have an influence on one another. It is difficult to improve one factor without affecting others. Segmentation methods must be compared based on all three factors, as illustrated in an example wherein two methods are compared in a particular application domain. The weight given to each factor depends on application.     

Increased tissue-type plasminogen activator activity in orthotopic but not heterotopic liver transplantation: the role of the anhepatic period.

The major cause of the increased tissue-type plasminogen activator activity during orthotopic liver transplantation is still unclear. Both the lack of hepatic clearance of tissue-type plasminogen activator in the anhepatic period and increased endothelial release from the graft on reperfusion have been proposed as the major causes. Heterotopic liver transplantation avoids the resection of the host liver and is a useful model to help differentiate between these two possibilities. In this study the fibrinolytic system was evaluated in 10 orthotopic liver transplantations, 18 heterotopic liver transplantations and a control group of 10 partial hepatic resections. A marked increment in tissue-type plasminogen activator activity, from 0.2 to 5.2 IU/ml (p less than 0.02), was observed during the anhepatic period of orthotopic liver transplantation, which rapidly normalized after reperfusion. In contrast, tissue-type plasminogen activator activity levels remained normal in heterotopic liver transplantation and partial hepatic resections. In orthotopic liver transplantation and in heterotopic liver transplantation no increase occurred in tissue-type plasminogen activator activity after reperfusion. The first venous hepatic outflow after reperfusion did not contain elevated tissue-type plasminogen activator activity levels. Plasma degradation products of fibrin and fibrinogen increased during the anhepatic period of orthotopic liver transplantation (from 2.60 to 8.80 micrograms/ml [p less than 0.008] and from 0.40 to 1.60 micrograms/ml [p less than 0.04], respectively) and remained elevated thereafter. In heterotopic liver transplantation and partial hepatic resections these levels remained low. In conclusion, the lack of hepatic clearance during the anhepatic period is probably the most important factor in the evolution of increased tissue-type plasminogen activator activity during orthotopic liver transplantation.     

Mild haemostatic problems associated with congenital heterozygous alpha 2-antiplasmin deficiency

A Dutch family, of which 13 members are heterozygotes, deficient for alpha 2-antiplasmin (alpha 2-AP) is reported. Clinical studies showed that 2 heterozygotes had a mild bleeding tendency, which presented as bleeding episodes after tooth extraction and after surgery and, in one patient, also as excessive menstruation. Laboratory investigations revealed an alpha 2-AP activity of 62% (51-71) (median and range) and an antigen level of 60% (60-66). The plasminogen binding as well as the fibrin binding properties of alpha 2-AP were normal. Plasminogen concentrations were significantly higher in the heterozygotes compared to the other family members. However, free plasminogen not bound to histidine-rich glycoprotein was not significantly different between these two groups. We propose that in this family the deficiency of alpha 2-AP is due to a decreased synthesis of a normal alpha 2-AP molecule. This present study brings the frequency of heterozygous alpha 2-AP deficient patients with a bleeding tendency to 13 out of 59 heterozygotes reported in the literature.     

Some new aryl-sydnones: effects on murine tumours.

The effects of new aryl-sydnones: 3-[4-X-3-nitrophenyl]-1,2,3-oxadiazolium-5-olates, where X = Cl (SYD-1); pyrrolidino (SYD-2); piperidino (SYD-3) and morpholino (SYD-4) on the survival of mice bearing Sarcoma 180, Ehrlich carcinoma, B10MCII (Fibrous histiocytoma) and L1210 leukemia ascitic tumours, on the proliferation of cultured tumour cells and on the synthesis of DNA in L1210 leukemia were determined. SYD-1 and SYD-2 in vivo significantly enhanced the survival of S180, Ehrilich and B10MCII tumour-bearing mice. Furthermore, SYD-2 showed significant activity against L1210. SYD-3 and SYD-4 did not show antitumour activity. SYD-1, in vitro was the most cytotoxic against all the above tumour cells. All of the drugs tested inhibited thymidine uptake by L1210 cells, SYD-4 being the least active.     

Colonization with methicillin-resistant Staphylococcus aureus after liver transplantation.

Methicillin-resistant Staphylococcus aureus (MRSA) is a frequent cause of infection after orthotopic liver transplantation (OLT). Colonization with MRSA is associated with a higher risk of infection. Previous studies have shown a high prevalence of MRSA colonization among OLT candidates. However, the risk of colonization with MRSA after OLT is still unclear. The objective of this study was to estimate the incidence and the factors associated with colonization with MRSA after OLT. This was a prospective cohort study including patients submitted to OLT between the years 2000 and 2002. Surveillance cultures of nasal swab specimens were performed within the 1st 72 hours of hospital admission and, subsequently, on weeks 2, 6, 13, and 26. Patients whose baseline cultures revealed nasal carriage of MRSA were excluded. A total of 60 patients were included in the study. The median follow-up was 72 days. A total of 9 patients (15%) became colonized. In multiple logistic regression analyses, the use of a urinary catheter for > or =5 days (P = .006), postoperative bleeding at the surgical site (P = .009), and preoperative use of fluoroquinolones (P = .08) were associated with a higher risk of colonization. Patients without any of these risk factors did not become colonized. In conclusion, nasal carriage of MRSA is frequently acquired after OLT. Periodic postoperative screening for MRSA carriage should be an integral component in programs designed to reduce nosocomial MRSA transmission in these patients. Further studies are needed to set up and validate a predictive model that could allow targeting postoperative screening to high-risk OLT recipients.