Acetylcholine receptors in human thymic myoid cells in situ: an immunohistological study

Myoid cells were studied by double immunofluorescence in sections of thymus from 47 patients with myasthenia gravis and 15 control subjects, using polyclonal sheep anti-troponin T and monoclonal antibodies to troponin I, striated muscle myosin, and acetylcholine receptor (AChR). The myoid cells were rare and located mainly in the medulla, and most were clearly positive for AChR; labeling was similar with four individual monoclonal antibodies specific for extrajunctional AChR and five that also recognize endplate AChR. They were mostly keratin-positive and consistently HLA-DR-negative. In the myasthenia gravis samples, the myoid cells were similar but largely confined to medullary epithelial areas; AChR labeling was slightly weaker, but otherwise they did not differ noticeably from those of control subjects. A preliminary finding was of even rarer AChR-positive/HLA-DR-positive antigen-presenting (possibly) cells seen in 9 of 9 myasthenia gravis samples and in none of 9 control samples. Although myoid-cell AChR appears antigenically similar to extrajunctional muscle AChR, and must therefore express the epitopes that myasthenics' antibodies recognize, these cells do not appear to be foci of immunological stimulation in myasthenia gravis.     

Load to failure of common meniscal repair techniques: Effects of suture technique and suture material

Success of meniscal repair with early or immediate motion depends on the ability of the suture fixation to withstand the loads applied. Vertical and horizontal mattress suture techniques were tested using 2-0 Ethibond, and 0-PDS and 1-PDS sutures (Ethicon, Somerville, NJ). Mulberry knot technique was tested with 0-PDS and 1-PDS sutures. Twenty menisci (60 sutures) were tested for each suture material. Sutures were placed 3 to 4 mm from the peripheral edge of the meniscus with double barreled cannulas for vertical and horizontal mattress techniques or a spinal needle for the mulberry knot technique, reproducing clinical techniques of meniscal repair. Mechanical testing of suture fixation was performed to failure at a rate of 10 mm/min on a MTS material testing system (MTS Systems Corp. Minneapolis, MN). Suture pullouts were reported as the load displacement to failure from the inner fragment only, because clinical failure would ensue should a suture pull through the inner fragment of a tear. Vertical mattress technique with 1-PDS suture had significantly greater load to failure than any other combination (P < .05). Analysis of variance showed that the vertical mattress technique had statistically superior pullout strength (P < .0001) compared with the horizontal mattress and mulberry knot techniques, which were statistically similar. There were significant differences (P < .0001) between suture types, with 1-PDS proving best compared with 0-PDS, which was stronger than 2-0 Ethibond. Selection of suture material had the greatest impact on vertical mattress load to failure and was not important to the strength of the other techniques.     

A method of simultaneous dual-radionuclide cardiac imaging with technetium 99m and thallium 201. I: Analysis of interradionuclide crossover and validation in phantoms

Background  

Simultaneous dual-radionuclide technetium 99m/thallium 201 scintigraphy can potentially produce perfectly aligned stress and rest images in less time than conventional protocols. However, interradionuclide crossover limits diagnostic accuracy. Accordingly, we evaluated^99mTc and²⁰¹Tl crossover in line and heart phantoms.     

Organization of intensive care units in Europe: lessons from the EPIC study

Objective: To study differences related to intensive care unit (ICU) structure and patient demography between the various countries of Western Europe. Design: Application of data collected by the European Prevalence of Infection in Intensive Care (EPIC) study, a one-day prevalence study. Setting: Voluntary participation of all Western European ICUs. A total of 1417 ICUs responded. Patients: All patients, older than 10 years of age, occupying a bed in the participating ICUs over a 24-h period. 10 038 patient case reports were submitted. Results: The study revealed important differences. In particular, there seems to be a north/south divide with fewer ICU beds and more severely ill patients in the south. The United Kingdom seemed more similar to southern European countries than to the north. Conclusion: While there are similarities between European countries, large differences still remain and are important to identify to enable us to work together to create a more uniform system of intensive care, which will in turn give more effective and efficient patient care. Received: 7 February 1997 Accepted 8 July 1997     

Hyperaemia in rat neocortex produced by acute exposure to methylenedioxymethamphetamine

Cerebral blood flow and glucose utilization were measured in rat neocortex, hippocampus and striatum following methylenedioxymethamphetamine injection (5 mg/kg, i.v.), using the tracers [¹⁴C]iodoantipyrine and [¹⁴C]2-deoxyglucose, respectively. In control rats, blood flow was coupled to glucose metabolism, but in methylenedioxymethamphetamine-treated rats, marked hyperperfusion was measured in frontal and parietal cortex with no change in glucose use. This suggests that methylenedioxymethamphetamine has the potential to disrupt cerebrovascular control.     

Reoperation for prosthetic heart valve replacement

From 1974 to 1984, 847 heart valve replacement operations were performed with 1005 prosthetic valves. Thirty-nine (4.6%) were reoperations with 43 prosthetic valve replacements (PVR), on 38 patients. Thirty-three patients had received their initial valve replacement in our hospital and 5 elsewhere. Twenty additional cardiac procedures were required, concomitantly with the prosthesis replacement. Twenty-three patients underwent replacement of a mechanical prosthesis (61%) an average of 4.3 years after initial implantation and 15 patients a bioprosthesis (39%) after 2.8 years. Indications for PVR were endocarditis in 15 patients (39%), prosthesis failure in 13 (34%), periprosthetic leak in 7 (18%), thrombosis in 2 (5%), and a left ventricle subannular aneurysm in 1 (3%). Preoperatively 4 patients were in NYHA functional class II (11%), 15 in class III (39%) and 19 in class IV (50%). Six patients died early postoperatively (15.8%) Various risk factors were analyzed. The early mortality rate was 22% for mechanical prosthesis replacement and 7% for bioprosthesis; 11% for aortic position, 13% for mitral position and 50% to 100% for double valve replacement; 23% for non-elective and 6% for elective operations; 10% for patients with only an initial valve replacement and 43% with additional previous valve operations; 18% for active endocarditis, 15% for prosthesis failure, 14% for periprosthetic leak, 0% for thrombosis and 100% for subannular aneurysm; 0% for patients in class II, 7% in class III and 26% in class IV; 6% in patients with an aortic cross-clamp time less than 2 hours and 24% with more; 27% prior to 1981 and 9% during the last 4 years; and finally 50% in patients over the age of 60.(ABSTRACT TRUNCATED AT 250 WORDS)