Constructing robust selves after brain injury: positive identity work among members of a female self-help group

Despite common experiences of identity damage, decline, and deterioration, many brain injury survivors succeed in reconstructing robust identities in the wake of injury. Yet, while this accomplishment greatly benefits survivors’ quality of life, little is known about how positive identity work might be facilitated or enhanced in therapeutic institutions. Drawing on data from a women’s self-help group, we argue that an egalitarian, reflective, strength-focused, and gender-segregated environment can provide female ABI (acquired brain injury) survivors with a fertile scene for identity enhancement and offer unique opportunities for collective identity development. Sociolinguistic interactional analysis revealed four types of positive identity work undertaken within the group: constructing competent selves; tempering the threat of loss and impairment; resisting infantilisation and delegitimisation; and asserting a collective gender identity. This identity work was facilitated by specific programme attributes and activities and contributed to the global project of decentring disability and destigmatising impairments and losses. We call for increased attention to identity issues in brain injury rehabilitation and argue that gender-segregated programming can provide a unique space for female survivors to construct empowering individual and collective identities after injury.     

Increased alpha suppression with age during involuntary memory retrieval

Recent work suggests that while voluntary episodic memory declines with age, involuntary episodic memory, which comes to mind spontaneously without intention, remains relatively intact. However, the neurophysiology underlying these differences has yet to be established. The current study used electroencephalography (EEG) to investigate voluntary and involuntary retrieval in older and younger adults. Participants first encoded sounds, half of which were paired with pictures, the other half unpaired. EEG was then recorded as they listened to the sounds, with participants in the involuntary group performing a sound localization cover task, and those in the voluntary group additionally attempting to recall the associated pictures. Participants later reported which sounds brought the paired picture to mind during the localization task. Reaction times on the localization task were slower for voluntary than involuntary retrieval and for paired than unpaired sounds, possibly reflecting increased attentional demands of voluntary retrieval and interference from reactivation of the associated pictures respectively. For the EEG analyses, young adults showed greater alpha event-related desynchronization (ERD) during voluntary than involuntary retrieval at frontal and occipital sites, while older adults showed pronounced alpha ERD regardless of intention. Additionally, older adults showed greater ERD for paired than unpaired sounds at occipital sites, likely reflecting visual reactivation of the associated pictures. Young adults did not show this alpha ERD memory effect. Taken together, these data suggest that involuntary memory is largely preserved with age, but this may be due to older adults' greater recruitment of top-down control even when demand for such control is limited.     

Increased glucose excursion in cystic fibrosis and its association with a worse clinical status

BACKGROUND: Abnormal glucose tolerance is a frequent co-morbidity in cystic fibrosis patients (CF), and is associated with a worse prognosis. The objectives are to investigate (a) the relative contribution of insulinopenia and insulin resistance (IR) for glucose tolerance and (b) the association between various glucose parameters and CF clinical status. METHODS: Oral glucose tolerance tests were performed in 114 consecutive CF patients not known to be diabetic as well as 14 controls similar for age and BMI. RESULTS: Abnormal glucose tolerance was found in 40% of patients with CF: 28% had impaired glucose tolerance (IGT) and 12% had new cystic fibrosis related diabetes (CFRD). Compared to control subjects, all CF patients were characterized by an increased glucose excursion (AUC). While reduced early insulin release characterised CF, IGT and CFRD patients also present IR thus both mechanisms significantly contribute to glucose tolerance abnormalities. Increased glucose AUC and reduced early insulin release but not glucose tolerance categories were associated with a reduced pulmonary function (FEV(1)). CONCLUSION: In CF, early insulin secretion defect but also IR contribute to glucose intolerance. Early in the course of the disease, increased glucose AUC and reduced early insulin secretion are more closely associated with a worse clinical status than conventional glucose tolerance categories.     

31P MRS of heart grafts provides metabolic markers of early dysfunction.

OBJECTIVE: Early graft failure (EGF) is a life-threatening event still accounting for a significant percentage of early deaths after heart transplantation. We tested whether selected metabolic markers, including high-energy phosphate concentrations measured ex vivo in pre-transplant heart grafts by (31)P magnetic resonance spectroscopy (MRS) are related with early post-transplant outcome. METHODS: During a 3-year period, 26 heart grafts harvested in the vicinity of the transplantation centre were studied. Evaluation of transplantability was done conventionally. (31)P MRS was performed ex vivo approximately 60min after aortic cross-clamp to quantify ATP, P(i) and PCr concentration ratios. A MRS-score was defined as a combination of intracellular pH (pHi) and the PCr/P(i) ratio. EGF was defined as the need to abnormally extend circulatory support or to use more than two inotropes before weaning the patient from CPB after transplantation. The grafts were attributed to three groups as follows: A1, transplanted with uneventful outcome (n=14); A2, transplanted with subsequent EGF (n=3) and B, not suitable for transplantation (n=9). RESULTS: Significant differences between groups existed for the following metabolic markers: PCr/ATP (P=0.013), PCr/P(i) (P=0.0004), pHi (P=0.0016) and MRS-score (P=0.0001). The sensitivity, specificity and positive likelihood ratio for EGF with a MRS-score相似文献   

Use of the ATP bioassay to assess toxic effects in marsh treatment systems

A firefly luciferase bioluminescent assay of bacterial adenosine triphosphate (ATP) was used to measure the toxic effects of metal ions on six bacterial genera isolated from two geographically different marsh treatment systems. The toxicity of eleven different metals, as well as metal mixtures, was monitored using the agar plate test and the resazurin reduction test in addition to measurement of intracellular ATP. All the organisms surveyed tended to be sensitive to much lower concentrations of metals when the metals were present in mixtures. Isolates from a marsh system constructed on normal soil exhibited lower metal resistance patterns than organisms isolated from a marsh built on mine tailings. The intracellular ATP assay appeared to be the most sensitive method of determining the viability of bacterial cells following metal treatment.     

Tacrolimus Pharmacokinetics and Dose Monitoring After Lung Transplantation for Cystic Fibrosis and Other Conditions

In cystic fibrosis (CF), absorption of tacrolimus through the gastrointestinal tract may be impaired due to fat malabsorption. The aim of this pilot study was to compare tacrolimus pharmacokinetics and inter- and intrasubject variability of exposure in stable lung transplant recipients with and without CF, and to determine the best single-time predictors of exposure. The study included 11 lung transplant recipients with CF and 11 without CF who received tacrolimus twice daily. Blood samples were obtained predose and at 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8 and 12 h postdose on 3 separate days within 1 week. Tacrolimus pharmacokinetics and inter- and intrasubject variability of exposure were similar in the two groups, though exposure-per-milligram-dose was approximately 50% lower in CF patients. Tacrolimus trough concentration did not accurately predict the area under the concentration curve (AUC(0-12)), but the concentration measured 3 h postdose (C(3)) was tightly correlated with the AUC(0-12) in both CF (r(2)= 0.86) and non-CF (r(2)= 0.92) patients. In summary, patients with CF have a higher tacrolimus oral clearance, but nonsignificant differences in short-term inter- and intrasubject variability of exposure compared to patients without CF. C(3) is tightly correlated with AUC(0-12) in lung transplant recipients with and without CF.     

ATP release from human airway epithelial cells studied using a capillary cell culture system

Epithelial release of adenosine triphosphate (ATP), an important autocrine and paracrine signalling molecule, is acutely mechanosensitive and therefore difficult to study. We describe here a novel preparation that minimizes mechanical and metabolic perturbations, and use it to examine ATP secretion by epithelial cells. The Calu-3 cell line derived from human airway sub-mucosal glands was cultured in a hollow fibre bioreactor on porous capillaries that were perfused by a re-circulating medium pump. Cells became polarized and cultures were stable for > 5 months, as evidenced by microscopy and lactate production (≈250 μg (10⁸ cells)⁻¹ day⁻¹). Elevating apical flow rate 5-fold increased ATP secretion from ≈200 to 6618 fmol min⁻¹. Reducing apical osmolarity by 25–43 % also increased ATP secretion, which then declined spontaneously to a plateau rate that persisted as long as hypotonic perfusion was maintained. Release deactivated rapidly after shear and osmotic stresses were terminated, and was not associated with detectable cell lysis. Lowering apical [Ca²⁺] to increase connexin hemichannel permeability also stimulated ATP release and increased secretion during both hyposmotic and shear stress; however, the connexin 43 blocker flufenamic acid inhibited shear-induced ATP release only in low-Ca²⁺ solution, and therefore another secretory pathway may operate with physiological (i.e. m m ) calcium. Regardless of the mechanism, the present results quantify ATP responses to mechanical and osmotic stimuli and demonstrate the usefulness of capillary cultures for studying epithelial secretion.     

The 21-aminosteroid antioxidant, U74389F, prevents estradiol-induced depletion of hypothalamic β-endorphin in adult female rats

A single intramuscular injection of 2 mg estradiol valerate (EV) results in neuronal degeneration and β-endorphin depletion in the hypothalamic arcuate nucleus of adult female rats. We have hypothesized that peroxidase-positive astrocytes in this brain region oxidize estrogens and catecholestrogens to semiquinone radicals which mediate oxidative neuronal injury. In the present study, dietary administration of the potent antioxidant 21-aminosteroid, U-74389F, completely blocked EV-induced β-endorphin depletion in the hypothalami of adult female rats. Neither EV nor 21-aminosteroid treatment had any effect on hypothalamic concentrations of neuropeptide Y and Met-enkephalin, confirming that the estradiol lesion is fairly selective for the β-endorphin cell population. The present findings support the hypothesis that the toxic effect of estradiol on hypothalamic β-endorphin neurons is mediated by free radicals.