Adaptation of the black yeast Wangiella dermatitidis to ionizing radiation: molecular and cellular mechanisms.

Observations of enhanced growth of melanized fungi under low-dose ionizing radiation in the laboratory and in the damaged Chernobyl nuclear reactor suggest they have adapted the ability to survive or even benefit from exposure to ionizing radiation. However, the cellular and molecular mechanism of fungal responses to such radiation remains poorly understood. Using the black yeast Wangiella dermatitidis as a model, we confirmed that ionizing radiation enhanced cell growth by increasing cell division and cell size. Using RNA-seq technology, we compared the transcriptomic profiles of the wild type and the melanin-deficient wdpks1 mutant under irradiation and non-irradiation conditions. It was found that more than 3000 genes were differentially expressed when these two strains were constantly exposed to a low dose of ionizing radiation and that half were regulated at least two fold in either direction. Functional analysis indicated that many genes for amino acid and carbohydrate metabolism and cell cycle progression were down-regulated and that a number of antioxidant genes and genes affecting membrane fluidity were up-regulated in both irradiated strains. However, the expression of ribosomal biogenesis genes was significantly up-regulated in the irradiated wild-type strain but not in the irradiated wdpks1 mutant, implying that melanin might help to contribute radiation energy for protein translation. Furthermore, we demonstrated that long-term exposure to low doses of radiation significantly increased survivability of both the wild-type and the wdpks1 mutant, which was correlated with reduced levels of reactive oxygen species (ROS), increased production of carotenoid and induced expression of genes encoding translesion DNA synthesis. Our results represent the first functional genomic study of how melanized fungal cells respond to low dose ionizing radiation and provide clues for the identification of biological processes, molecular pathways and individual genes regulated by radiation.

Long-term consequences of kidney donation.

BACKGROUND: The long-term renal consequences of kidney donation by a living donor are attracting increased appropriate interest. The overall evidence suggests that living kidney donors have survival similar to that of nondonors and that their risk of end-stage renal disease (ESRD) is not increased. Previous studies have included relatively small numbers of donors and a brief follow-up period. METHODS: We ascertained the vital status and lifetime risk of ESRD in 3698 kidney donors who donated kidneys during the period from 1963 through 2007; from 2003 through 2007, we also measured the glomerular filtration rate (GFR) and urinary albumin excretion and assessed the prevalence of hypertension, general health status, and quality of life in 255 donors. RESULTS: The survival of kidney donors was similar to that of controls who were matched for age, sex, and race or ethnic group. ESRD developed in 11 donors, a rate of 180 cases per million persons per year, as compared with a rate of 268 per million per year in the general population. At a mean (+/-SD) of 12.2+/-9.2 years after donation, 85.5% of the subgroup of 255 donors had a GFR of 60 ml per minute per 1.73 m(2) of body-surface area or higher, 32.1% had hypertension, and 12.7% had albuminuria. Older age and higher body-mass index, but not a longer time since donation, were associated with both a GFR that was lower than 60 ml per minute per 1.73 m(2) and hypertension. A longer time since donation, however, was independently associated with albuminuria. Most donors had quality-of-life scores that were better than population norms, and the prevalence of coexisting conditions was similar to that among controls from the National Health and Nutrition Examination Survey (NHANES) who were matched for age, sex, race or ethnic group, and body-mass index. CONCLUSIONS: Survival and the risk of ESRD in carefully screened kidney donors appear to be similar to those in the general population. Most donors who were studied had a preserved GFR, normal albumin excretion, and an excellent quality of life.

Cystatin C is not superior to creatinine-based models in estimating glomerular filtration rate in former kidney donors.

BACKGROUND: The long-term renal consequences of kidney donation need to be accurately quantitated. Cystatin C is a freely filtered glycoprotein that may not have the limitations of creatinine as a measure of glomerular filtration rate (GFR). Whether cystatin C is superior to creatinine-based estimates of GFR in those who have donated a kidney in the past has not been tested. METHODS: We assessed the performance of seven cystatin C and two creatinine-based GFR prediction equations in 187 former kidney donors against iohexol GFR for measuring GFR. We calculated bias, precision, and relative accuracy of these models. RESULTS: The majority of former donors had a GFR >60 mL/min/1.73 m(2). All cystatin C models, except the Rule model, overestimated GFR (range 5.3-31.4 mL/min/1.73 m(2)). Among the cystatin C models, the Hoek and Rule formulas were least biased at 5.3 and -3.8 mL/min/1.73 m(2), most precise at 0.41, and were within 30% of iohexol GFR, 89.3 and 96% of the time, respectively. The Modification of Diet in Renal Disease (MDRD) formula underestimated GFR by 7.2 mL/min/1.73 m(2), was most precise (R(2)=0.47) and fell within 30% of measured GFR at the highest frequency of 96%. When all models were given a rank based on their performance in the bias, precision and accuracy domains, the MDRD model was clearly superior. CONCLUSION: The MDRD equation is superior to cystatin C-based equations for estimating GFR in former kidney donors. Creatinine measurement is cheaper and the MDRD GFR is given out by most laboratories and therefore it should be the preferred model in this population.

Quantifying the extent of femoral head involvement in osteonecrosis.

BACKGROUND: There are numerous methods for quantifying the extent of osteonecrosis of the femoral head. However, there is no consensus regarding which method is the most reliable. The purpose of this study was to determine the reliability and prognostic accuracy of three commonly used methods for quantifying the extent of osteonecrosis of the femoral head. METHODS: Thirty-nine hips in twenty-five patients who had stage-I or II osteonecrosis of the femoral head, according to the grading system of the Association Research Circulation Osseous, were independently examined on two separate occasions by three observers of different specialty backgrounds and experience. Each observer used three methods to quantify the extent of osteonecrosis of the femoral head: (1) the index of necrotic extent, (2) the modified index of necrotic extent, and (3) the percentage of femoral head involvement. The interobserver and intraobserver agreement was determined for each method, and the ability of each method to predict the time to subchondral collapse was analyzed statistically. RESULTS: There was significantly valid agreement among the observers for all three methods (p < 0.001 for all three). The correlation coefficients demonstrated substantial agreement among raters when they measured the index of necrotic extent and the percent involvement and nearly perfect agreement when they measured the modified index of necrotic extent. Survivorship analysis revealed that the percent involvement (p < 0.05), index of necrotic extent (p < 0.007), and modified index of necrotic extent (p < 0.04) were prognostically significant predictors of subchondral fracture. CONCLUSIONS: Our results indicate that the index of necrotic extent, modified index of necrotic extent, and estimation of the percentage of involvement of the femoral head are reproducible and reliable methods for quantitatively evaluating the extent of osteonecrosis of the femoral head. We believe that the three methods can be utilized with confidence. Furthermore, they are clinically useful for identifying hips at greatest risk for subchondral collapse.

Osteonecrosis of the femoral head after solid organ transplantation: a prospective study.

BACKGROUND: The reported prevalence of osteonecrosis of the femoral head in patients who have undergone a solid organ transplant has ranged from 3% to 41%. The wide variation is due to the retrospective nature of most studies and the inability to capture data on asymptomatic patients. The primary goals of this study were to determine the true prevalence of osteonecrosis of the femoral head following solid organ transplantation, the time to the development of the osteonecrosis, and whether findings on magnetic resonance imaging precede the onset of symptoms. METHODS: Beginning in 1997, patients who had undergone a solid organ transplant were asked to participate in a prospective study in which they would be screened for osteonecrosis of the femoral head. Inclusion criteria included an age of greater than fourteen years, a first-time transplant, and magnetic resonance imaging performed within six months after the transplant. Exclusion criteria were pre-existing osteonecrosis of the femoral head in the hip included in the study, a history of inflammatory arthritis, previous hip surgery, any contraindication to magnetic resonance imaging, a prior organ transplant, prior systemic corticosteroid treatment, and mental health issues preventing adequate follow-up. Screening magnetic resonance imaging was performed every four months. Survivorship analysis was used to determine the prevalence of osteonecrosis of the femoral head. RESULTS: Fifty-two patients (103 hips) were enrolled in the study. Their ages ranged from twenty-four to sixty-five years (mean, forty-three years). Sixteen patients were dropped from the study, but the data collected on them before they were dropped were included in the analysis. Osteonecrosis of the femoral head was diagnosed in eight of the 103 hips. Survivorship analysis revealed that, at one year after the transplant, 89% +/- 7% of the hips and 80% +/- 13% of the patients were free of osteonecrosis of the femoral head; thus the prevalence of osteonecrosis one year after transplantation was 11% or 20%, respectively. The mean duration of follow-up of the remaining hips was 2.3 years. In two hips the osteonecrosis of the femoral head was seen on the initial screening magnetic resonance imaging, and in the other six it developed after the initial magnetic resonance imaging revealed negative findings. All cases of osteonecrosis of the femoral head developed within ten months after the transplant. Seven of the eight hips were asymptomatic at the time of diagnosis. There was a significant difference in the one-year osteonecrosis-free survival rate between the patients who were less than forty years old (78%) and those who were at least forty years old (97%) (p = 0.011). Diabetes, smoking, and rejection episodes were not risk factors for osteonecrosis of the femoral head. CONCLUSIONS: Our study of patients who had had a solid organ transplant revealed that the true prevalence of osteonecrosis of the femoral head in such patients is lower than that reported in most previous studies, osteonecrosis of the femoral head develops prior to the onset of symptoms, an age of less than forty years is a risk factor for osteonecrosis of the femoral head, and osteonecrosis of the femoral head develops within one year after transplantation. We recommend that magnetic resonance imaging be used to screen for osteonecrosis of the femoral head within one year after transplantation. The utility of additional magnetic resonance imaging after one year has not been established.

Systematic detection and multidisciplinary care of delirium in older medical inpatients: a randomized trial.

BACKGROUND: Delirium is common and often goes undetected in older patients admitted to medical services. It is associated with poor outcomes. We conducted a randomized clinical trial to determine whether systematic detection and multidisciplinary care of delirium in older patients admitted to a general medical service could reduce time to improvement in cognitive status. METHODS: Consecutive patients aged 65 or more who were newly admitted to 5 general medical units between Mar. 15, 1996, and Jan. 31, 1999, were screened with the Confusion Assessment Method within 24 hours after admission to detect prevalent delirium and rescreened within a week to detect incident cases. Patients with delirium were randomly allocated to receive the intervention or usual care. Subjects in the intervention group were seen by a geriatric specialist consultant and followed in hospital for up to 8 weeks by an intervention nurse who liaised with the consultant, attending physicians, family and the primary care nurses. Subjects in the usual care group received standard hospital services but could consult geriatric specialists as needed. A research assistant, blinded as to treatment allocation, administered within 24 hours after enrolment the MiniMental Status Exam (MMSE), Delirium Index (measuring the severity of the delirium) and Barthel Index (measuring independence of personal care). Improvement was defined as an increase in the MMSE score of 2 or more points, with no decrease below baseline plus 2 points, or no decrease below a baseline MMSE score of 27. A short form of the Informant Questionnaire on Cognitive Decline in the Elderly was completed to identify patients with possible dementia. Subjects were assessed 3 times during the first week and weekly thereafter for up to 8 weeks in hospital or until discharge. Data on clinical severity of illness, length of stay and living arrangements after discharge were also collected. The primary outcome measure was time to improvement in MMSE score. RESULTS: Of the 1925 patients who met the inclusion criteria and were screened, 227 had prevalent or incident delirium and consented to participate (113 in intervention group and 114 in usual care group). There were no clinically significant differences between the intervention and usual care groups except for sex (female 58.4% v. 50.0%) and marital status (married 34.8% v. 41.2%). Overall, 48% of the patients in the intervention group and 45% of those in the usual care group met the predetermined criteria for improvement. The Cox proportional hazards ratio (HR) for a shorter time to improvement with the intervention versus usual care, adjusted for age, sex and marital status, was 1.10 (95% confidence interval [CI] 0.74-1.63). There were no significant differences within 8 weeks after enrolment between the 2 groups in time to and rate of improvement of the Delirium Index, the Barthel Index, length of stay, rate of discharge to the community, living arrangements after discharge or survival. Outcomes between the 2 groups did not differ statistically significantly for patients without dementia (HR 1.54, 95% CI 0.80-2.97), for those who had less co-morbidity (HR 1.36, 95% CI 0.75-2.46) or for those with prevalent delirium (HR 1.15, 95% CI 0.48-2.79). INTERPRETATION: Systematic detection and multidisciplinary care of delirium does not appear to be more beneficial than usual care for older patients admitted to medical services.