Gastroepiploic veins: CT appearance in pancreatic disease.

The frequency with which gastroepiploic vein (GEV) enlargement was seen on CT and its relevance to disease of the portal venous system associated with pancreatic disease were studied. We performed a retrospective study of 50 patients with proved pancreatic disease and another 50 patients without such disease. The CT examinations were done in incremental dynamic fashion after a bolus injection of contrast medium. Scans were evaluated for collateral channel formation, including GEV enlargement, and for involvement of the portal venous system by pancreatic disease. Part of the GEV arcade was visible in 36 patients without pancreatic disease, and on average measured 3.2 mm in diameter (range, 1-5.5 mm). GEV enlargement was visible in 62% of the patients with disease; 16% demonstrated a vessel 6 mm or more in diameter. Thirty-four percent of the patients with disease had portal venous complications: 26% had isolated splenic vein involvement, 2% had isolated portal vein involvement, and 6% had a combination of splenic and portal vein involvement. Of the patients with splenic vein disease, 81% had collateral channel formation, 50% of them demonstrating isolated GEV enlargement. Patients with splenic vein disease due to acute pancreatic disease had a much higher instance of GEV enlargement (83.3%). Collateral vessels are commonly seen on CT scans of patients with splenic vein disease and most often occur via enlarged GEVs. Acute pancreatic disease is frequently associated with GEV enlargement, suggesting that the latter represents an early response to splenic vein disease. In contrast, multiple collateral pathways tend to develop in patients with chronic pancreatic disease.     

Evaluation of three substitutes for Percoll in sperm isolation by density gradient centrifugation

Silane-coated silica particle solutions (ISolate(TM) and PureSperm)TM)) and iodixanol (OptiPrep(TM)) were compared to polyvinylpyrrolidone (PVP)-coated silica particles (Percoll(TM)) in their efficacy to recover spermatozoa by gradient centrifugation for use in assisted reproductive procedures. Efficacy was assessed in terms of percentages of sperm recovery, sperm vitality and motility, normal sperm morphology and normal sperm chromatin condensation. No significant difference was found in the recovery of spermatozoa for men with both normal sperm counts and oligozoospermia, between PVP-coated and silane-coated particle solutions. Iodixanol had significantly lower sperm recovery compared to the other products. Sperm vitality, progressive motility, normal morphology and normal chromatin condensation did not differ significantly between any of the sperm isolation products.      

Novel Method for Processing Respiratory Specimens for Detection of Mycobacteria by Using C18-Carboxypropylbetaine: Blinded Study

A novel method for processing respiratory specimens to improve culture and acid-fast staining of mycobacteria is introduced. This new method utilized N,N-dimethyl-N-(n-octadecyl)-N-(3-carboxypropyl)ammonium inner salt (Chemical Abstract Service no. 78195-27-4), also known as C₁₈-carboxypropylbetaine (CB-18). In a blinded, five-center study, CB-18-based processing was compared to the standard method combining NALC and NaOH (NALC/NaOH). A total of 573 respiratory specimens were tested. Individual specimens were split approximately equally; the host institutions processed half of each specimen by the NALC/NaOH method, while the other half was processed with CB-18 at Quest Diagnostics—Baltimore. A total of 106 specimens were culture positive for acid-fast bacilli (AFB). Replacement of the primary decontamination agent with CB-18 caused changes in all diagnostic parameters. Aggregate culture sensitivity improved by approximately 43% (P < 0.01), and smear sensitivity improved by approximately 58% (P < 0.01). The sensitivity of smear relative to that of M. tuberculosis isolates exceeded 93% (P < 0.01) when specimens were processed with CB-18. The average times to a positive result were reduced by 7.3 days in liquid culture (P < 0.01) and 5.3 days on solid media (P < 0.05); however, the CB-18 method had a 20.8% contamination rate in liquid culture versus a rate of approximately 7.5% with NALC/NaOH processing. There were also unusual reductions in liquid culture sensitivity and smear specificity among CB-18-processed specimens. The characteristics of the latter parameters suggested that refinement of the CB-18 processing method should allow further improvements in culture sensitivity. This study showed that the CB-18 method has the potential to improve both smear and culture detection for these important human pathogens.     

Detection and identification of gastrointestinal microsporidia using non-invasive techniques.

AIMS--To detect enteric microsporidia in faecal specimens from patients with the acquired immunodeficiency syndrome (AIDS), and to identify the spores to species level without using invasive procedures. METHODS--Formalised faecal preparations were examined using a modification of the strong trichrome staining method to demonstrate microsporidian spores. Six positive specimens were prepared for electron microscopy by emulsification and separation using a 9% Ficoll gradient. RESULTS--The modified staining technique readily identified microsporidian spores. Spores of different species showed variation in size. Identification using electron microscopy was successful for five of the six positive specimens examined. It was unsuccessful for one specimen in which spores were less abundant on initial staining. CONCLUSIONS--The modified strong trichrome staining method is a useful way of detecting spores of intestinal microsporidia in faecal specimens. Variation in spore size may permit provisional identification by light microscopy. Electron microscopic examination of faecal preparations is useful for identifying spores to species level.     

Evaluation of new blood culture processing systems

The Antimicrobial Removal Device (ARD; Marion Scientific) was evaluated in vitro with simulated blood culture samples in fresh blood and clinically with samples from potentially septic patients to test its ability to remove antimicrobial agents and recover bacteria from blood culture specimens containing these drugs. In simulated specimens, the ARD was evaluated for adverse affects on microorganisms as well as compared with lysis-centrifugation (Isolator; Du Pont Co.), biphasic brain heart infusion bottles, and tryptic soy broth bottles for antimicrobial inactivation and organism recovery. There was no adverse effect of the ARD on organisms during a 4-h test period. The ARD was the only system to actually inactivate antimicrobial agents and removed greater than 99.2% of all antimicrobial agents tested from spiked and clinical specimens. Overall, with simulated blood culture specimens, the ARD recovered 90% of bacteria spiked into fresh blood containing antimicrobial agents, Isolator recovered 73%, biphasic brain heart infusion bottles recovered 31%, and tryptic soy broth bottles recovered 24%. In the clinical study, 43 of 86 clinically significant isolates were recovered only by ARD-assisted processing, 6 were recovered only by conventional processing, and 37 were recovered by both methods (the advantage of ARD processing over conventional processing in the clinical study was significant at P less than 0.001). Both clinical and simulated specimens demonstrated the ARD-associated blood culture processing to be the most efficient method for the isolation of microorganisms from specimens containing antimicrobial agents.     

Simultaneous reorganization in thalamocortical ensembles evolves over several hours after perioral capsaicin injections.

Reorganization of the somatosensory system was quantified by simultaneously recording from single-unit neural ensembles in the whisker regions of the ventral posterior medial (VPM) nucleus of the thalamus and the primary somatosensory (SI) cortex in anesthetized rats before, during, and after injecting capsaicin under the skin of the lip. Capsaicin, a compound that excites and then inactivates a subset of peripheral C and Adelta fibers, triggered increases in spontaneous firing of thalamocortical neurons (10-15 min after injection), as well as rapid reorganization of the whisker representations in both the VPM and SI. During the first hour after capsaicin injection, 57% of the 139 recorded neurons either gained or lost at least one whisker response in their receptive fields (RFs). Capsaicin-related changes continued to emerge for >/=6 h after the injection: Fifty percent of the single-neuron RFs changed between 1-2 and 5-6 h after capsaicin injection. Most (79%) of these late changes represented neural responses that had remained unchanged in the first postcapsaicin mapping; just under 20% of these late changes appeared in neurons that had previously shown no plasticity of response. The majority of the changes (55% immediately after injection, 66% 6 h later) involved "unmasking" of new tactile responses. RF change rates were comparable in SI and VPM (57-49%). Population analysis indicated that the reorganization was associated with a lessening of the "spatial coupling" between cortical neurons-a significant reduction in firing covariance that could be related to distances between neurons. This general loss of spatial coupling, in conjunction with increases in spontaneous firing, may create a situation that is favorable for the induction of synaptic plasticity. Our results indicate that the selective inactivation of a peripheral nociceptor subpopulation can induce rapid and long-evolving (>/=6 h) shifts in the balance of inhibition and excitation in the somatosensory system. The time course of these processes suggest that thalamic and cortical plasticity is not a linear reflection of spinal and brainstem changes that occur following the application of capsaicin.