Immunological and echocardiographic evaluation of decellularized versus cryopreserved allografts during the Ross operation.

OBJECTIVE: Compare the immunological and echocardiographic data of decellularized versus cryopreserved allografts used for RVOT reconstruction during Ross operation. METHODS: From 16/01/03 thru 07/10/03, 20 Ross operations were performed using decellularized (n=11) or cryopreserved (n=9) allografts. Echocardiography was done at discharge, 1, 3, 6 and 12 months and annually thereafter. Samples for determination of antibodies against HLA class I and II were obtained preoperatively and at days 5, 10, 30, 90 and 180 postoperatively. These samples were tested by the ELISA method in LAT-M dishes (unspecific) for identification of circulating antibodies and the results expressed as mean sample values (Is=DO/cutoff). If positive, LAT-E (specific) was performed and PRA levels determined. RESULTS: There was no mortality. Cryopreserved allografts showed marked Is values elevations for class I and II antibodies which started at the first month and remained elevated up to 6 months. In contrast, of the patients receiving decellularized allografts, seven remained negative, two patients had only marginal elevation of class I antibodies and two patients showed abnormal elevations of PRA levels. This response happened earlier than in the cryopreserved group, starting on the 5th postoperative day and has returned to baseline levels in one case. Echocardiography showed mild, but significant, elevation of gradients in cryopreserved valves but none in the decellularized. CONCLUSIONS: Decellularized allografts had normal function up to 18 months and showed important reduction of the immunogenic response when compared to cryopreserved valves.     

Secrets of success of a human pathogen: molecular evolution of pandemic clones of meticillin-resistant Staphylococcus aureus

The first European isolate of meticillin-resistant Staphylococcus aureus (MRSA) was detected in 1960. Since then MRSA has become a leading cause of nosocomial infections worldwide. Using molecular typing techniques--primarily pulsed-field gel electrophoresis (PFGE)--we identified five major MRSA clones that accounted for almost 70% of the over 3000 MRSA isolates recovered in hospitals mainly in southern and eastern Europe, South America, and the USA. Most of our surveillance studies were done in these areas. Multilocus sequencing typing (MLST) of representative isolates of this collection showed that these five pandemic MRSA clones have evolved from only two distinct ancestral genetic backgrounds, one of which can be traced back to the very first European MRSA isolates and also to meticillin susceptible S aureus strains circulating in Danish hospitals during the mid to late 1950s--i.e., shortly before the introduction of meticillin into therapy. The second lineage with a completely different MLST profile included MRSA frequently recovered in the USA, Japan, and among paediatric isolates from several parts of the world. A few isolates with a third distinct MLST type corresponding to that of EMRSA-16 were also detected in the early Danish isolates. The four structural types of mec element, the heterologous DNA segment containing the meticillin resistance determinant mecA, were present in unique combinations with the MRSA clonal types. Our findings establish evolutionary associations in the most widely spread pandemic clones of MRSA. The epidemiological factors that contributed to the massive dissemination of a few MRSA clones are not well understood. We suggest, however, that the secrets of effectiveness of MRSA could be hidden in the unique genetic background of a surprisingly few lineages of S aureus particularly well able to cope with the contemporary clinical environment.     

Gallbladder-associated ectopic liver: A rare finding during a laparoscopic cholecystectomy

INTRODUCTIONEctopic hepatic tissue is due to an uncommon failure of embryological liver development that is rarely described in the world medical literature. The incidence of ectopic liver (EL) has been reported to be anywhere from 0.24% to 0.47% as diagnosed at laparotomy or laparoscopy. We describe a case of EL adherent to the gallbladder, removed at laparoscopic cholecystectomy.PRESENTATION OF CASEA 37-year-old female was admitted for elective cholecystectomy having had an episode of acute cholecystitis provoked by gallstones. During the procedure, a 30 mm × 10 mm × 5 mm section of EL tissue attached to the anterior wall of the gallbladder was identified and removed by en-bloc excision during laparoscopic cholecystectomy. Histological examination confirmed the absence of malignant degeneration of the hepatic tissue. The patient recovered well postoperatively and was discharged the day after the operation. She was well when seen six months later.DISCUSSIONEL has been reported in several sites, such as the gallbladder, gastrohepatic ligament, adrenal glands, esophagus, and thoracic cavity. EL is often clinically silent and discovered incidentally during abdominal surgical procedures or autopsies. Because patients with ectopic liver may suffer complications such as torsion, peritoneal bleeding, fatty change, and evolution to cirrhosis or malignant degeneration to hepatocellular carcinoma, any ectopic liver tissue needs to be correctly identified and removed.CONCLUSIONDespite the rare occurrence of EL, it should be recognized and removed by the surgeon to prevent a higher risk of complications and malignant transformation.     

Sequential treatment of progressive multifocal leukoencephalopathy with intravenous immunoglobulins and pembrolizumab

Journal of NeuroVirology - Progressive multifocal leukoencephalopathy (PML) is a rare demyelinating disease of the CNS caused by the human polyomavirus 2 (JCV). PML predominantly occurs in...     

Multiplex PCR strategy for subtyping the staphylococcal cassette chromosome mec type IV in methicillin-resistant Staphylococcus aureus: 'SCCmec IV multiplex'

OBJECTIVES: To develop and validate a new multiplex PCR strategy for subtyping SCCmec type IV methicillin-resistant Staphylococcus aureus (MRSA) strains-SCCmec IV multiplex PCR. METHODS: Seven primer pairs were designed to detect the ccrB allotype 2 (internal positive control), the five polymorphic J1 regions described so far for SCCmec type IV and the new J1 region specific for EMRSA-15. Primer sets were tested for specificity and robustness with prototype strains for each subtype of SCCmec type IV. The multiplex PCR conditions were optimized in a trial-error approach. RESULTS: The seven prototype strains for the earlier described subtypes of SCCmec type IV and the EMRSA-15 prototype strain were correctly characterized by our strategy. Moreover, 13 diverse SCCmec type IV strains could be assigned to a subtype of SCCmec type IV and 5 EMRSA-15 strains were assigned to the new subtype IVh. One strain could not be assigned to an SCCmec type IV subtype because of the absence of amplification of the specific J1 region. CONCLUSIONS: This new strategy, based on a single multiplex PCR reaction, is adequate for the rapid assignment of all major subtypes of SCCmec type IV described so far and also the new subtype IVh characteristic of EMRSA-15. This strategy complements well the previously described multiplex PCR assay for the rapid assignment of SCCmec types.     

Physiological time series: distinguishing fractal noises from motions

Many physiological signals appear fractal, in having self-similarity over a large range of their power spectral densities. They are analogous to one of two classes of discretely sampled pure fractal time signals, fractional Gaussian noise (fGn) or fractional Brownian motion (fBm). The fGn series are the successive differences between elements of a fBm series; they are stationary and are completely characterized by two parameters, sigma2, the variance, and H, the Hurst coefficient. Such efficient characterization of physiological signals is valuable since H defines the autocorrelation and the fractal dimension of the time series. Estimation of H from Fourier analysis is inaccurate, so more robust methods are needed. Dispersional analysis (Disp) is good for noise signals while bridge detrended scaled windowed variance analysis (bdSWV) is good for motion signals. Signals whose slopes of their power spectral densities lie near the border between fGn and fBm are difficult to classify. A new method using signal summation conversion (SSC), wherein an fGn is converted to an fBm or an fBm to a summed fBm and bdSWV then applied, greatly improves the classification and the reliability of H, the estimates of H, for the times series. Applying these methods to laser-Doppler blood cell perfusion signals obtained from the brain cortex of anesthetized rats gave H of 0.24+/-0.02 (SD, n=8) and defined the signal as a fractional Brownian motion. The implication is that the flow signal is the summation (motion) of a set of local velocities from neighboring vessels that are negatively correlated, as if induced by local resistance fluctuations.