Mlh1 can function in antibody class switch recombination independently of Msh2

Mismatch repair proteins participate in antibody class switch recombination, although their roles are unknown. Previous nucleotide sequence analyses of switch recombination junctions indicated that the roles of Msh2 and the MutL homologues, Mlh1 and Pms2, differ. We now asked if Msh2 and Mlh1 function in the same pathway during switch recombination. Splenic B cells from mice deficient in both these proteins were induced to undergo switching in culture. The frequency of switching is reduced, similarly to that of B cells singly deficient in Msh2 or Mlh1. However, the nucleotide sequences of the Smu-Sgamma3 junctions resemble junctions from Mlh1- but not from Msh2-deficient cells, suggesting Mlh1 functions either independently of or before Msh2. The substitution mutations within S regions that are known to accompany switch recombination are increased in Msh2- and Mlh1 single-deficient cells and further increased in the double-deficient cells, again suggesting these proteins function independently in class switch recombination. The finding that MMR functions to reduce mutations in switch regions is unexpected since MMR proteins have been shown to contribute to somatic hypermutation of antibody variable region genes.     

FcepsilonRI signaling observed from the inside of the mast cell membrane

Crosslinking the high affinity IgE receptor, FcrepsilonRI, on basophils and mast cells initiates cascades of biochemical events leading to degranulation, membrane ruffling and other physiological responses. Downstream of FcepsilonRI and its coupled tyrosine kinases, Lyn and Syk, scores of different proteins and lipids are implicated in these signaling cascades and new players are being identified continuously. Here, we use immunogold probes to label receptors and signaling proteins on the cytoplasmic face of membrane sheets prepared from RBL-2H3 mast cells and transmission electron microscopy to examine their distributions in relationship to each other and to features of the membrane. New topographical data are integrated with existing knowledge of the biochemistry of FcepsilonRI signaling and of cell shape during signaling to implicate at least two distinct membrane domains in FcepsilonRI signaling. "Primary signaling domains", also called osmiophilic patches, are recognized by their dark staining with osmium, adjacency to coated pits (previously mapped to planar membrane between lamellae) and by the characteristic presence of receptor, Syk and PLCgamma2, but not Lyn. "Secondary signaling domains" are characterized by the presence of large elliptical linker for activation of T cells (LAT) rafts and of PLCgamma1 (previously mapped to lamellae) but not receptor. The signaling proteins, Vav, Grb2, Cbl and Gab2, and the endocytic proteins, AP2 and clathrin, all map to the primary domains, while the p85 regulatory subunit of phosphatidylinositol 3 (PI 3)-kinase maps to both domains. Recognition that FcepsilonRI signaling is controlled not only by which chemical species are available for interaction, but also by where the interactions occur, may provide new opportunities for the modeling of signaling cascades and new targets for the development of drugs to treat allergies and asthma.     

Management of intractable constipation with antegrade enemas in neurologically intact children

OBJECTIVES: To assess the benefit of antegrade enemas in children with severe constipation who were referred to a tertiary care center. METHODS: From 1997 to 1999, 12 children (9 male, aged 8.7 +/- 4.4 years) underwent cecostomy placement. All children were neurologically normal and had been extensively examined to rule out organic causes of constipation. Follow-up included a questionnaire to interview caregivers 13.1 +/- 8.5 months after cecostomy placement. RESULTS: For all children, antegrade enemas led to improvement in the number of bowel movements / week (7.1 versus 1.4, P < 0.005), number of soiling accidents / week (1.0 versus 4.7, P < 0.01), abdominal pain score (0.9 versus 2.9, P < 0.005), emotional health score (3.6 versus 1.9, P < 0.005), overall health score (3.6 versus 1.7, P < 0.005), number of medications used for constipation (0.8 versus 4.0, P < 0.005), number of missed school days / month (1.5 versus 7.5, P < 0.02), and number of physician office visits / year (9.2 versus 24.0, P < 0.05). Irrigation solutions used for the antegrade enemas included polyethylene glycol (67%), saline and glycerin solution (25%), and phosphate enema (8%), administered everyday in seven children and every other day in five children. Adverse events included skin breakdown and granulation tissue in one patient, leakage of irrigation solution in one patient, and dislodging of the tube in two patients. Five patients discontinued the use of antegrade enemas within a mean of 14.6 +/- 9.1 months after beginning treatment. CONCLUSION: Antegrade enemas through a cecostomy are a safe and satisfactory option for children who are neurologically intact and who have severe constipation that does not respond to medical treatment.     

Stay in-the-know regarding informed consent

Informed consent hinges on educating patients about their proposed treatments.     

Driving performance in patients with mild to moderate glaucomatous clinical vision changes

The purpose of this study was to determine the relationship between clinical measures of visual function and driving-related skills in patients with glaucoma who had good visual acuity in at least one eye and mild to moderate visual field loss. METHODS: Twenty-five patients with glaucoma and twenty-nine age-equivalent normally sighted control subjects were included in the study. We tested each patient on an interactive driving simulator and collected vision data, including Lighthouse visual acuity, Goldmann and Humphrey visual fields, and Pelli-Robson contrast sensitivity. Information about real-world accident history for the previous 5-year period was obtained. RESULTS: The glaucoma patients did not have significantly more simulator or real-world accidents than the normally sighted group. There were no significant differences between the groups in performance on seven of the eight simulator indexes that were measured. Of the clinical visual function measures, only lower contrast sensitivity in the eye with better contrast sensitivity correlated with driving skills, including slower speeds (r(24) = 0.58, p < or = 0.01), more lane boundary crossings (r(24) = -0.54, p < or = 0.01), and longer braking response times (r(24) = -0.60, p < or = 0.01) for the patient group. CONCLUSION: Reduced contrast sensitivity may be important in indicating the level of driving skills for individuals with glaucoma, who have normal or near-normal visual acuity and mild to moderate visual field loss.     

Pressure area management: a static-led approach

An increase in expenditure and inappropriate use of pressure-relieving equipment, along with high-prevalence figures, initiated the evaluation of current practice of pressure damage prevention in an acute general hospital. This evaluation started with the organization of a project group, who (after a baseline audit) identified and procured the resources required to introduce and manage an effective pressure damage prevention programme. The investment in high-quality static mattresses for all patients including those who are at high risk of developing pressure damage was based on available clinical evidence. This investment meant a reduction in the amount of dynamic systems needed as many of those patients are at high risk of pressure damage, and are now successfully managed on a static system. The development of a local policy including documentation facilitated regular reassessment of risk level based on a risk assessment tool and clinical rationale. This static-led approach has reduced not only costs but also improved the appropriate allocation of pressure-relieving/reducing equipment. The approach has also simplified the choice of equipment for staff who were previously expected to match patients' needs with varying levels of dynamic mattress efficiency. This article highlights the action taken from the initial identification of a specific need through to the effective implementation, management and monitoring of this innovative practice.     

Treatment and prevention of diaphragm fatigue using low-dose dopamine

There is increasing evidence that diaphragm fatigue is a major cause of failure in weaning patients from mechanical ventilation. Patients in intensive care units are often administered dopamine to improve renal blood flow without regard to its effect on diaphragm blood flow. The aim of this study was to investigate if intravenous low-dose dopamine, equivalent to the dose used in intensive care units, can treat and prevent diaphragm fatigue. Diaphragm fatigue was produced in anesthetized rats by inspiratory resistance loading (IRL). The effect on diaphragm shortening, diaphragm blood flow, and aortic blood flow was determined. When diaphragm fatigue was attained, group I was given saline for 30 min while maintaining IRL. At the time of diaphragm fatigue, group II was given low-dose dopamine (2 microg/kg/min) for 30 min while maintaining IRL. In group III, dopamine administration was started before and continued throughout the period of IRL. Administering dopamine after the development of diaphragm fatigue (group II) increased diaphragm performance as measured by increased diaphragm shortening and was accompanied by an increased diaphragm blood flow. Administering dopamine prior to and throughout IRL (group III) prevented diaphragm fatigue. Low-dose dopamine can prevent and/or reverse diaphragm fatigue in rats without a significant change in aortic blood flow. This effect of dopamine may be due to increased oxygen delivery associated with the increased diaphragm blood flow, resulting in less free radical formation and thus less muscle damage.     

Transitions in American hospitals: the necessary reshaping is taking place. "Turnaround" processes in organizations

American hospitals are reshaping and redefining the way they are managed and the way they provide care. More American healthcare organizations are stating that they are in a turnaround situation. Although there are no definite guidelines or criteria that place an organization in a turnaround situation, there are certain circumstances that are frequently present. These circumstances most often include a somewhat sudden change from a financially favorable situation. This may include revenue lost and/or increases in cost from operations, decreases in volumes that are most positive and favorable to the organization, sudden changes in key management or board representation, and sudden loss of key managers and staff needed for the successful operation of the organization. Any one of these factors or several can place an organization in such jeopardy that quick and decisive actions must be taken to ensure survival and future success. The specific conditions of a turnaround and the effectiveness of quick and decisive actions are critical for the survival of an organization or a system.