CMSS-VEPs: Contrast modulated steady state visual evoked potentials: Its neuronal origin and clinical use

CMSS-VEPs are presented as a sensitive, non-invasive functional investigation technique of the visual function, applicable in clinical practice. New improvements of the technique are presented. The underlying neuronal mechanisms are discussed. The clinical use is illustrated in a case of optic neuritis.     

Liver and intestine transplantation

The most significant development in liver transplantation in the USA over the past year was the full implementation of the MELD- and PELD-based allocation policy in March 2002, which shifted emphasis from waiting time within broad medical urgency status to prioritization by risk of waiting list death. The implementation of this system has led to a decrease in pretransplant mortality without increasing post-transplant mortality, despite a higher severity of illness at the time of transplant.
The trend over the last few years of rapidly increasing numbers of adult living donor liver transplants was reversed in 2002 by a decline of more than 30% in the number of these procedures. In 2002, a greater percentage of women received livers from living donors (43%) than deceased donors (34%), possibly because of size considerations.
From 1993 to 2001, the waiting list increased more than sixfold, from 2902 patients to 18 047 patients. For the first time since 1993, the waiting list size decreased in 2002, dropping 6% to 16 974 candidates. The percentage of temporarily inactive liver candidates also increased from 2001, thus the net decrease in the active waiting list for 2002 was 12%. This may reflect a trend toward less pre-emptive listing practices under MELD.
Intestine transplantation remains a low-volume procedure limited to a few transplant centers and is still accompanied by significant pre- and post-transplantation risks. As this procedure matures, its application may increase to include recipients at an earlier stage of their disease with better likelihood of success.     

Alterations in the ultrastructure of cardiac autonomic nervous system triggered by crotoxin from rattlesnake (Crotalus durissus cumanensis) venom.

This study explored the toxic effects of crotoxin isolated from Crotalus durissus cumanensis venom on the ultrastructure of mice cardiac autonomic nervous system. Mice were intravenously injected with saline (control group) and crotoxin diluted in saline venom (study group) at a dose of 0.107 mg/kg mouse body weight. Samples from the inter-ventricular septum were prepared for electron microscopy after 6 h (G1), 12 h (G2), 24 h (G3) and 48 h (G4). The G1 group showed some cardiomyocyte with pleomorphic mitochondria. Capillary swollen walls, nerve cholinergic endings with depleted acetylcholine vesicles in their interior and other depletions were observed. A space completely lacking in contractile elements was noticed. The G2 group demonstrated a myelinic figure, a subsarcolemic region with few myofibrils and nervous cholinergic terminal with scarce vacuoles in their interior. The G3 group demonstrated a structure with a depleted axonic terminal, mitochondrias varying in size and enhanced electron density. In addition, muscular fibers with myofibrillar structure disorganization, a depleted nervous structure surrounded by a Schwann cell along with an abundance of natriuretic peptides, were seen. An amyelinic terminal with depleted Schwann cell and with scarce vesicles was also observed. Finally, axonic lysis with autophagic vacuoles in their interior and condensed mitochondria was observed in the G4 group. This work describes the first report of ultrastructural damage caused by crotoxin on mice cardiac autonomic nervous system.     

Neurocysticercosis in Persons with Epilepsy in Medellín,Colombia

Summary: Purpose: A prospective series of 643 persons with epilepsy attending a reference neurologic center in Medellin, Colombia, was examined by computed tomography (CT scan) or serology or both with the enzyme-linked immunoelectrotransfer blot assay (EITB) to assess the prevalence of Taenia solium cysticercosis. Methods: All presenting patients were consecutively enrolled in the study. Five hundred forty-six persons underwent cerebral CT scans; 376 of them also had serum EITB performed. Results: Prevalence of neurocys@ercosis by CT scan was 13.92%. Overall prevalence of T. solium antibodies with EITB was 9.82%, but for those with late-onset epilepsy (onset after age 30 years), prevalence increased to 17.5% and 19% for those who originated from outside urban Medellin. Seroprevalence in individuals with mixed lesions (cysts and calcifications) was 88.2% and 64.10% in those with live cysts. Conversely, only 2.72% of persons with CT findings not related to neurocysticercosis had positive EITB tests. Conclusions: Our study shows that an important proportion of individuals with epilepsy have radiologic or serologic evidence of T. solium infection, suggesting that neurocysticercosis is an important etiology for epilepsy in Colombia.     

The hemolysin of escherichia coli

Many strains of E. coli elaborate a hemolysin which is responsible for the zone of -hemolysis surrounding bacterial colonies on blood agar. The significance of this cytolysin as a determinant of bacterial pathogenicity has been established in animal models with the use of genetically engineered, isogenic bacterial strains. An analogous role in human infections has been inferred from the high association of hemolysin production with disease. Studies at a molecular genetical level have defined 4 genes that are required for the synthesis, post,translational modification and secretion of the hemolysin. The structural gene hlyA encodes for a 107-110 000 polypeptide, which must be modified in an unknown manner to its active form by the product of the neighboring hlyC gene. Genes hlyb and hlyD encode for proteins that export the molecule to the extracellular medium. The signal for secretion is contained in the C-terminal portion of the toxin molecule. The secreted hemolysin attacks plasma membranes of target mammalian cells by inserting as a monomer into the bilayer and generating hydrophilic transmembrane pores of approximately 2 nm effective diameter. The pores display a marked selectivity for cations over anions and pore-opening is dependent on the presence of a correct transmembrane potential. Binding to a membrane target does not require the presence of a specific receptor, and pores may be generated in planar lipid membranes consisting solely of phosphatidylcholine. Pore formation in nucleated cells can trigger secondary reactions such as stimulation of arachidonate metabolism with release of lipid mediators, probably initiated by passive influx of extracellular Ca²⁺. Perfusion of subcytolytic doses through isolated and ventilated rabbit lungs induces lung edema that is at least partially due to such secondary events. The capacity of E. coli hemolysin to damage human tissues via primary and secondary processes is consistent with the concept of its pathogenic role in human infections.[/p]Corresponding author.     

Major histocompatibility complex class I peptide presentation after Salmonella enterica serovar typhimurium infection assessed via stable isotope tagging of the B27-presented peptide repertoire

Reactive arthritis (ReA) induced by infection with several gram-negative bacteria is strongly associated with expression of the major histocompatibility complex class I molecule HLA-B27. It is thought that due to the intracellular lifestyle of ReA-inducing bacteria, bacterial fragments can be presented by HLA-B27. Cytotoxic T cells recognizing such bacterial peptides or other induced host peptides could cross-react with self peptides presented in the joints, giving rise to disease. Studies to analyze the B27 peptide repertoire in relation to infection were severely hampered, as complex peptide profiles obtained from separate infected and noninfected cell preparations had to be compared. For this study, we applied a new approach to examine the effect of Salmonella enterica serovar Typhimurium infection on the B27 peptide repertoire presented by the HLA-B*2704 subtype associated with disease. Firstly, we showed that both host cell and S. enterica serovar Typhimurium proteins can be tagged metabolically with stable-isotope-labeled arginine. We then designed experiments so that either the tagged endogenous or tagged bacterial B*2704-presented peptide repertoires from infected cells could be analyzed by mass spectrometry from single peptide preparations that included uninfected controls. Using this new approach, we found no evidence for significant changes in endogenous B*2704 peptide presentation after infection or for any S. enterica serovar Typhimurium-derived B27-bound peptide. In conclusion, the hypothesis that S. enterica serovar Typhimurium induces changes in B27 peptide presentation could not be supported.     

Relationship between adherence to inhaled corticosteroids and poor outcomes among adults with asthma

BACKGROUND: Regular use of inhaled corticosteroids (ICSs) can improve asthma symptoms and prevent exacerbations. However, overall adherence is poor among patients with asthma. Objective To estimate the proportion of poor asthma-related outcomes attributable to ICS nonadherence. METHODS: We retrospectively identified 405 adults age 18 to 50 years who had asthma and were members of a large health maintenance organization in southeast Michigan between January 1, 1999, and December 31, 2001. Adherence indices were calculated by using medical records and pharmacy claims. The main outcomes were the number of asthma-related outpatient visits, emergency department visits, and hospitalizations, as well as the frequency of oral steroid use. RESULTS: Overall adherence to ICS was approximately 50%. Adherence to ICS was significantly and negatively correlated with the number of emergency department visits (correlation coefficient [ R ] = -0.159), the number of fills of an oral steroid ( R = -0.179), and the total days' supply of oral steroid ( R = -0.154). After adjusting for potential confounders, including the prescribed amount of ICS, each 25% increase in the proportion of time without ICS medication resulted in a doubling of the rate of asthma-related hospitalization (relative rate, 2.01; 95% CI, 1.06-3.79). During the study period, there were 80 asthma-related hospitalizations; an estimated 32 hospitalizations would have occurred were there no gaps in medication use (60% reduction). CONCLUSIONS: Adherence to ICS is poor among adult patients with asthma and is correlated with several poor asthma-related outcomes. Less than perfect adherence to ICS appears to account for the majority of asthma-related hospitalizations.     

Autogeny in Ochlerotatus vigilax (Diptera: Culicidae) from southeast Queensland, Australia

Field and laboratory investigations were undertaken to determine the level of expression of autogeny in the mosquito Ochlerotatus vigilax (Skuse) from southeast Queensland, Australia, and whether there was evidence of seasonal variation. At two field sites in southeast Queensland, Wellington Point and Donnybrook, autogeny rates were determined on six occasions between January 2001 and January 2002. The autogeny rate varied between 71 and 100% at Wellington Point and between 63 and 100% at Donnybrook. Autogenous fecundity ranged from 17 to 63 eggs per female at Wellington Point and from 13 to 88 eggs per female at Donnybrook. Positive relationships were found between adult body size (indicated by wing length), autogeny rate, and fecundity. A laboratory study was conducted to investigate the influence of larval nutrition and adult diet (water versus sucrose) on the expression of autogeny. The autogeny rate at a low-diet treatment was between 73 and 90% when sucrose was withheld from females and 100% when sucrose was provided. All high-diet females were autogenous. Autogenous egg development required 80 +/- 6 h from emergence at 27 degrees C. We conclude that autogeny rates are consistently high in Oc. vigilax from the southeast Queensland region.